PREFACE
This annual report reviews the research activities of the Laboratory of Advanced Scienceand Technology for Industry (LASTI) in the academic year of 2010 (April 2010 –March
2011) including activities using a 1.5GeV synchrotron radiation facility “ NewSUBARU ” atthe site of SPring-8 and other research activities of the micro and nanoscale are carried out
energetically in CAST building.
Topics of the NewSUBARU research activities of this year are as follows. First is thebasic characteristic research of NewSUBARU electron storage ring and photo-nuclear
reaction with laser Compton scattering Gamma-ray. The second is EUV (extreme
ultraviolet) activities that are a mask observation using a coherent EUV scattering microscope,nanostructure pattern replication by EUV interference lithography system, and developmentof in-situ contamination measurement in the EUV resist outgassing environment. BL09C
beamline was branched from BL09B beamline for usage of the EUV interference lithography
for evaluation of the exposure characteristics of EUV resist. Third is micro- and nano-devices
such as a three-dimensional lab-on-CD and X-ray grating for X-ray Talbot interferometer.
Fourth is the material science for various materials such as Si-containing DLC, BN and GaN.
Furthermore, the performance of analysis beam line BL5 for industrial enterprises wasevaluated by NEXAFS spectra measurements using the standard samples of graphite, BN,
LiCl and MgO.
Most of our research activities are being conducted in collaboration with industries,
government research institutes and other universities.
We will continue to respond to the community’s demand by offering new science andtechnologies.

Shinji Matsui
Director of LASTIi

ii

CONTENTS
PREFACE ....................................................................................................................... γ
CONTENTS ......................................................................................................................  ε
ORGANIZATION ................................................................................................ η
CURRENT STATUS OF NewSUBARUNewSUBARU Storage Ring ..................................................................................  1
Beamlines ..............................................................................................................  3
Center for EUV Lithography ................................................................................  9Study on High Brightness Operation of NewSUBARU without RF Shaker ......  11
RESEARCH ACTIVITIESUpgrade Plan of 15MeV Compact Electron Linear Accelerator LEENA asa Terahertz Radiation Source ...........................................................................  13
Photonuclear reaction of iodine-129 with laser-Compton scattering gamma-ray 15
Determination of the number of pulsed laser-Compton scattering photons ......  17
Resonant Photonuclear Reactions for Isotope Transmutation ...........................  21
Soft X-ray Source by Laser Produced Xe Plasma ................................................  27
Characterization of a laser-plasma extreme-ultraviolet source using
a rotating cryogenic Xe target ...........................................................................  29
Soft X-Ray from Laser-Produced Xe and Sn Plasmas in a Wide
Wavelength Range .............................................................................................  31
Study on Powder Transport Using Surface Acoustic Wave Actuator ..................  33
HIGH-SENSITIVE DETECTION OF POLYCHLORINATED BIPHENYLON THREE-DIMENSIONAL LAB-ON-A-CD ..................................................  35
Fabrication of Integrated Magneto Impedance Sensor for Medical Monitoring  37
Fabrication of Gold Nanoparticles Assembled Nanovalleyfor Surface
Enhanced Raman Scattering ..............................................................................  39
Coherent Scatterometry Microscope (CSM) .........................................................  41
EUV Finished Mask Observation utilizing EUV Microscope .............................  42
EUV Interference Lithography .............................................................................  43
In-situ contamination thickness measurement in the EUV
resist outgassing environment ..........................................................................  44
Optical element evaluation system ......................................................................  45
Classification of Near-Edge X-ray Absorption Fine
Structure Spectra of Si-containing DLC Thin Films .......................................  46
Sulfur L3.2-edge XANES spectroscopy reveals differencesin sulfur speciation of reference S compounds  .............................................  48
The Present Status of Material Analysis Beamline
at BL05 for Industrial Enterprises ...................................................................  49
Low-Temperature Crystallization of a-Si, a-Ge anda-SiGe Films by Soft X-ray Irradiation ............................................................  51

iii

Photoelectron Spectroscopy Study of the Valence Band
Region in Diamond-Like Carbon Thin Films .................................................  52
Characterization of Crystalline Structure of BN Thin Filmusing Soft X-ray Absorption Spectroscopy .........................................................  54
Modification of Electronic States of Multi-walled Carbon
Nanotubes by Ion Irradiation .............................................................................  56
Damage analysis of gallium nitride crystals etched by He and Ar plasma ........  58
A Development Plan of Sputtering System for Large Scale
Telescope Mirror Coating at Nishi-Harima Astronomical Observatory ............  60
Fabrication of Carbon Membrane X-ray Mask for Deep X-ray
Lithography Technique .....................................................................................  62
Fabrication of Au Structure Using Direct Electroplating on Si Structures .......  64
Fabrication of High Performance Light Guide Plate ...........................................  66
Technique for Preparing Defect-free High Aspect Ratio SU-8
Resist Structure Using X-ray Lithography ......................................................  68
LIST OF PUBRICATIONSPapers ....................................................................................................................  71
International Meetings .........................................................................................  76
Award .....................................................................................................................  83
ACADEMIC DEGREES .................................................................................................  85
EDITORIAR BOAD .................................................................................................. 86

iv

The Organization ofLaboratory of Advanced Science and Technology for Industry
University of Hyogo
The organization
Director

Department ofLight and Particle Science and Technology!Advanced Photon System!Beam Physics!Nanostructure Science and Technology!Guest Chair

Steering
Committee

Department ofLight Aplication for Advanced Technology!Nanoscience and Technology utilizing
Synchrotron Radiation!Nano-Micro System!Bio-Medical Technology (to be established)!Guest Chair

Stuff (FY 2009)
Research and faculty staff

Administrative staff

MATSUI Shinji, Professor, Director
KANDA Kazuhiro, Professor
MIYAMOTO Shuji, Professor
KINOSHITA Hiroo, Professor
HATTORI Tadashi, Professor
WATANABE Takeo, Associate Professor
SHOJI Yoshihiko, Associate Professor
NIIBE Masahito, Associate Professor
UTSUMI Yuichi, Associate Professor
AMANO Sho, Research Associate
HASHIMOTO Satoshi, Research Associate
HARADA Tetsuo, Research Associate
HARUYAMA Yuichi, Research Associate
NODA Daiji, Research Associate

MUREI Masatoshi, General Manager
YOSHIDA Yasukazu, Manager
MIYAMOTO Ken-ichi, Chief
YOKOYAMA Yuka, CAST
KAMIYA Miki, CASTYAMAMOTO Keiko, CAST
KANATANI Naoko, NewSUBARUIMAIZUKI Masami, NewSUBARUMORIGUCHI Miyuki, Harima Forum of
Science and Technology for 21st Century

Open Advanced Research Facilities Initiative
Staff
MOCHIZUKI Takayasu
TERASAWA Mititaka
MOTOYAMA Muneyuki
FUKUOKA Takao
MIYAHARA Yoshikazu
ISHIKAWA Kazuko

Guest Staff
OHOKUMA Haruo, Professor (Guest)

Contact address
CAST (Center of Advanced Science and Technology, Hyogo)
3-1-2 Kouto, Kamigori-cho, Ako-gun, Hyogo, 678-1205 JAPAN.
T:+81-791-58-0249 F:+81-791-58-0242
NewSUBARU Synchrotron Radiation Facility
1-1-2 Kouto, Kamigori-cho, Ako-gun, Hyogo, 678-1205 JAPAN.
T:+81-791-58-2503 F:+81-791-58-2504
Web URL http://www.lasti.u-hyogo.ac.jp/,

http://www.lasti.u-hyogo.ac.jp/NS/

e-Maillasti@lasti.u-hyogo.ac.jp

Accsess

http://www.lasti.u-hyogo.ac.jp/NS-en/access/v

CURRENT STATUS OF NewSUBARUNewSUBARU Storage Ring
Y. Shoji
Storage Ring Parameters
The machine parameters of the 1.5 GeV storage
ring remain the same as those of the previous year.
They are listed in Table I.

The total machine time in FY2010 was 2608 hrs,
98% of that of FY2010, including the beam downtime. Fig. 1 shows the breakdown. The beam downtime includes not only the down by a failure, butalso off-beam periods by a beam abort or others dueto the beam instability. The normal user time in thisFY, 1489 hrs, was about 90% of that in FY2009.
Time for machine study and special users was 138%of that in FY2009.

Table I Main parameters of the NewSUBARU
storage ring in FY2008.
Circumference
118.73 m
Bending lattice typemodified DBA
Number of bending cells 6
Straight sections
4m X 4, 15m X 2
Bending radius
3.22 mInjection energy
1.0 GeV
Maximum energy
1.5 GeV
RF frequency
499.955 MHz
Betatron tune
6.30 (H), 2.21 (V)Momentum compaction factor
0.0014
Electron energy
1.0 GeV 1.5 GeV
RF voltage
100 kV 260 kV
Natural energy spread
0.047% 0.072 %Natural emittance
38 nm 67 nm
Maximum beam current 500 mA

Machine Troubles
The machine troubles in FY2010 are listed inTable II. The total down time was only 1.0% of thetotal machine time. It was about 2/3 of that in
FY2009 and 1/3 of that in FY2008. The main
troubles in FY2010 were related to the COD control
system.
We lost 4.6 hours of operation time related to the
newly installed continuous COD correction program.
We had some failures by software bugs and also
some miss-operations of GUI.
We lost 8.5 hours due to a large COD during theacceleration process from 1.0 GeV to 1.5 GeV,
although the current of the steering magnets werechanged according to a fixed pattern control table.
After the experiences of the beam loss by too large
COD at the acceleration, we recognized the shift of
the required current for the steering magnets. Figure
2 shows that the required current had changed day
by day especially at the beginning of the operation
cycle. With this knowledge, the operators reduced
the orbit shift by adjusting the rf frequency and thefailure almost disappeared. However, the reason of
the change is not known.

-0.7
-0.75
-0.8
-0.85
2008/ 11/01

2008/ 07/01-0.9
2008/ 03/01

user time1489 hrs(57%)

2007/ 11/01

machine study &special user time
727 hrs
(28%)

-0.6
-0.65

2007/ 03/01

beam down time by machine troubles
25 hrs (1.0 %)machine tuning
367 hrs
(14%)

-0.55

2007/ 07/01

steering magnet current (A)Operation Status
The ring has two user-time operation modes, 1.0
GeV top-up operation mode and 1.5 GeV operation
mode. Basic operation time is 9:00 - 21:00 of
weekdays. Monday is for machine R&D, Tuesday isfor 1.5 GeV user time, Wednesday and Thursday arefor 1.0 GeV top-up user time, Friday is for 1.0 GeV
or 1.5 GeV user time. Night period or weekend isused for machine study and user time with thespecial mode, single bunch operation and LaserCompton Gamma ray, if necessary.

date (y/m/d)Figure 2: Example of the change of a steering
magnet current after the COD correction. The
average current of six horizontal steering magnets at
dispersion sections is plotted. The values in the same
operation cycles were connected with lines. A
current shift of 0.1 A corresponds to an rf frequency
shift of 2.1 kHz/500 MHz, or a maximum horizontal
displacement of 3.4 mm.

Figure 1: Machine time in FY2010.

1

Machine Study and Special User Time
Table III shows the list of machine studies in
FY 2010. One special theme, a research related toa production of Laser-Compton backscattering ray and its use, took about 1/4 of the machine
study time as had been in passed FY.
Most of the study reports are open to the public
on the home page of NewSUBARU.

magnets. They were designed based on 3D fieldcalculation considering the interference with othermagnetic yokes nearby. The commissioning as thesteering magnets was successful. The change of thedeflection angle per current was less than a few %.
The new R&D aiming for the improvement of beam
lifetime started using their multi-pole field windings.

Accelerator Improvements
The ring had some improvements in FY2009.
Bunch current monitor, installed in FY2008
was organized to a new bucket filling control system.
It controls the bucket-selector for the injection andrealizes a wanted bucket filling.
The COD correction system started continuousworking. It operates slow COD correction routine
for every one minute. Some soft ware bugs were
found and fixed.
Four of the vertical steering magnets were
replaced by multi-element corrector magnets (Figure3). The new magnets worked as vertical steering
magnets with exactly the same parameters of the old
Table IIGroup
Operation

Figure 3: Four vertical steering magnets in thedispersion section were replaced by the multielement corrector magnets.

Machine troubles in FY2010.

Failure/trouble
beam down time (hr)Failure of COD control program
4.6
RF voltage control program trouble
2.2
Operation (others)
RF tuner position error
1.4High radiation at intentional beam abort
0.7
Large COD at 1.5 GeV
8.7
beam loss by a beam instabilities
2.6
Troubles at SPring-8 (delay of starting user time)
2.2
Electric power down by a thunder
2.3(software)

Table III List of machine studies in FY2010. The unit of study time is typically 12 hrs/shift.
R＆D theme and special user mode
responsible person study shift
Parameter tuning for 1.5 GeV acceleration
S. Hashimoto1
Betatron tune feedback system
S. Hashimoto
9
Commissioning of X-ray BPM at BL10
S. Hashimoto4
Beam profile measurement
S. Hashimoto2
Measurement of steering response function
Y. Minagawa
2
Laser-Compton backscattering -rays
S. Miyamoto
21
Confirmation of cancellation table of undulator effect
T. Shinomoto
2
Radiation shield for L4BT beam profile monitor
Y. Shoji1
Vertical beam oscillation at the beam injection
Y. Shoji1
Commissioning of the new profile monitor port SR5
Y. Shoji5
Commissioning of sextupole windings in the invert bends
Y. Shoji
8
Transverse beam matching at the beam injection
Y. Shoji7
Effect of the magnetic shield for the DC septum stray field
Y. Shoji1
Instability suppression by chromaticity modulation
Y. Shoji2
Detection of Coherent Synchrotron Radiation
Y. Shoji4
Measurement of beam orbit oscillation in 10 – 300Hz range
Y. Shoji1
Measurement of coherent betatroon oscillation damping time
Y. Shoji1
Measurement of skew-quadrupole field distribution in the ring
Y. Shoji2
Commissioning of octupole component of the multi-element corrector Y. Shoji1
Measurement of amplitude dependent tune shift
Y. Shoji
2
Ring parameter measurement for better lattice model
Y. Shoji1
Test of low emittance latticeY. Shoji22

Beamlines
Takeo Watanabe and Hiroo Kinoshita
Center for EUVL, LASTI, University of Hyogo

beamline for the usage of the thickness measurement of the
carbon contamination originated to the resist outgassing
during the EUV exposure.
BL02 beamline was constructed for the usage of LIGA
in 2003.
BL05 beamline was constracted in response to ademand in the industrial world, that is enhancement of theanalysis ability in the soft X-ray region with thedevelopment of nanotechnology.
The arrangement of the beamlines in the NewSUBARU
synchrotron radiation facility is shown in Fig.1.

Total nine beamlines are operating in the
NewSUBARU synchrotron facility. Four beamlines of
BL01, BL03, BL06 and BL11 were constructed until 1999.
Three beamlines of BL07, BL09 and BL10 were started theoperation from 2000.
BL03B beamline branched from the BL03 beamline
propose for the usage of the EUVL (extreme ultraviolet
lithography) microscope for the EUVL finished mask
inspection.
BL09B beamline branched from BL09 beamline for theusage of the usage of the EUV interference lithography toevaluate. And BL09C beamline branched from BL09B

Fig. 1 Beamline arrangement in NewSUBARU.
I. BL01
BL01 is a beamline for research and developing newlight sources. This beamline is one of two longstraight section on NewSUBARU. Optical klystron
was installed at this straight section. Upstream side of3

storage ring tunnel was constructed in 2004 for
gamma-ray irradiation experiments. Specificationsof this gamma-ray source are listed in Table 1.

this beamline (BL01B) is intended to be used forvisible and infrared light generated from FEL or SR.
Downstream side of this beamline (BL01A) is used
for laser Compton scattering gamma-rays source.
Gamma-ray beamline hutch just outside of theTable 1. Specification of BL01 gamma beam
CO2 laser
Gamma energy : 1.7 - 4 MeV
Gamma flux* : 9 x106 γ/s
10.52 μm
5W
: 6 x105 γ/s (1.5-1.7 MeV)
(with 3mmφ collimator)
Gamma energy : 17 - 40 MeV
Nd laser
Gamma flux* : 7.5 x106 γ/s
1.064 μm
0.532 μm
: 3 x105 γ/s (15-17 MeV)
5W
(with 3mmφ collimator)*Electron beam energy : 1-1.5 GeV*Electron beam current : 250 mA
gamma-ray beam divergence : 0.5 mrad
II. BL02
x-ray mirrors (plane and cylindrical mirror) and Be film
filters. The horizontal angle of the outgoing SR could beobtained up to 12.5 mrad, which corresponds to thehorizontal size of 220 mm (A4 horizontal size) at the
exposure position. The second characteristic performanceof the beamline is the high efficiency differential pumping
system. This was necessary for maintain the vacuum
difference between the storage ring (<10-9 Pa) and theend-station (<10-9 Pa) at which gasses for substrate coolingwill be introduced in the exposure apparatus.
The flexibility for the shapes and functions of
microstructure will be enlarged by achieving 3D
microfabrication process using multi step exposure atvarious configuration between x-ray mask and substrates.
The relative positions between x-ray mask and substrates,
tilt and rotation angle to the SR incident direction can be
moved simultaneously during SR exposure using 5 axis
stages. The movement of each axis is controlled by the PC
in terms of the scanning speeds, scanning length, andrepetition number. In order to decrease the heat load ofsample substrate suffered during SR irradiation helium
introduction and substrate cooling mechanism were alse
equipped. Specification of spectrometer is listed in Table 2.

The LIGA (abbreviated name of Lithogaphic,
Galvanoformung and Abformung) process which consistsfrom deep x-ray lithography, electroforming, and molding
process is one of the promising candidates for such 3D
micofabrication. More than hundreds aspect ratio for
microstructure can be attained by the usa of the higher
energy x-rays (4-15 keV) from synchrotron radiation (SR)with deeper penetration depth to the photosensitive resist.
In this system we have succeeded to enlarged the exposurearea up to A4 size and the fabrication dimension from
submicron to millimeter by varying the energy of the x-ray
source in accordance with the size of desired microparts.
Micostructure with high aspect ratio over several hundreds
will bi achieved using the x-rays over 10 keV since highenergy x-ray has deep penetration depth to thephoto-sensitive resist materials. Whereas, in the case oflithography for low energy x-rays from 1 keV to 2 keV,submicron structures with high aspect ratio will beachieved using the x-rays mask with precise line-width andthinner absorber, since low energy x-rays has low
penetration depth. Based on this principle, the beamilne for
x-ray exposure have constructed with continuous
selectivity of x-rays frpm 100 eV to 15 keV by using theTable 2. Specification of the LIGA exposure system
OpticsPlane and cylindrical mirror, Be filters
Exposure energy
100 - 2 keV, and 4 – 15 keV
Exposure method
Proximity and multi step exposure
Wafer size
A4 or 8 inch
Exposure area
230 mm(H) ×300 mm(V)
Exposure environment< 1 atm (He-gas)

4III. BL03
BL03 is a beamline for the developing the next
generation lithographic technology so called extreme
ultraviolet lithography (EUVL). The exposure tool isinstalled at the end station. Using this exposure tool, theresearch and development of the next generation
lithography such as the less than 70 nm node is going on
process. The exposure wavelength is 13.5 nm.
The semiconductor industry plays a very important rolein the information technology (IT). In 2006, 256 Gbit
DRAM with a gate length of 70 nm will be demanded in
the IT industry. The extreme ultraviolet lithography(EUVL) is a promise technology for fabricating a finepattern less than 70 nm. To meet this schedule, thistechnology has to be developed in the pilot line until 2004.
As for the practical use, it is very important that both toachieve large exposure area and to fabricate fine patterns.
Therefore, at Himeji Institute of Technology, large
exposure field EUV camera consists of three asphericalmirrors was developed. First in the world, we fabricated 60
nm line and space pattern in the large exposure area of 10
mm×10 mm on a wafer. Furthermore, BL03B beamline
branches from the BL03 beamline propose for the usage of
the EUVL microscope for the EUVL finished mask
inspection.

Table 3. Spectification of the exposure tool (ETS-1)
Imaging optics
Three aspherical mirrors
Exposure wavelength13.5 nm
Numerical aperture
0.1
Demagnification
1/5
Resolution
60 nm
Depth of focus
0.9 µmExposure area (static)
30 mm×1 mm
Exposure area (scanning)
30 mm×28 mm
Mask size
4 inch, 8 inch, and ULE 6025
Wafer size
8 inchExposure environment
In vacuum
IV. BL05
BL05 was constructed in response to a demand in theindustrial world, that is enhancement of the analysis ability
in the soft x-ray region with the development of
nanotechnology. BL05 consists of two branch lines for use
in the wide range from 50 eV to 4000 eV. BL05A and
BL05B are designed to cover the energy range of
1300-4000 eV and 50-1300 eV, respectively. The incident
beam from the bending magnet is provided for two branchlines through different windows of a mask. Therefore,
these two branch lines can be employed simultaneously.

1) The double crystal monochromator was installed at
the BL05A. InSb crystals and Si crystals are prepared for a
double-crystal monochromator. Toroidal mirrors are used
as a pre-mirror and a focusing mirror of BL05A. XAFS
measurement in the total electron yield mode andfluorescence XAFS measurement using SSD (SII Vortex)
can be performed. The fluorescence XAFS spectra can bemeasured for samples at the end station filled with He gas.

Table 4. Monochromator specification
Monochromator
Double crystal monochromator
Monochromator crystals
InSb(111), Si(111)Energy range
1300-4000 eV
E/∆E=3000
Resolution

on BL05B. The optical system consists of a first mirror(M0), a second mirror (M1), an entrance slit (S1), a
pre-mirror (M2), and three kinds of plane grating (G), an
exit slit (S2) and a focusing mirror (M3). The including2) The constant-deviation monochromator consisting of ademagnifying spherical mirror and a varied-line-spacing
plane grating (VLSPG), which can provide high resolution,
simple wavelength scanning with fixed slits, was mounted

5

photoelectron spectrum can be measured using sphericalelectron analyzer (VG Sienta, R3000) in an ultra
high-vacuum chamber. The chambers can be replaced byeach other within 1 hour.

angle of the monochromator is 175°. Two measurement
chambers are prepared at the end station of BL05B. The
XAFS spectra in the total electron yield mode andfluorescence XAFS spectra using SDD (EDAX) can bemeasured in a high vacuum chamber. In addition, theMonochromator
Grating
Energy range
Resolution

Table 5. Monochromator specification
Varied-line-spacing plane grating monochromator
100 l/mm, 300 l/mm, 800 mm/l
50-1300 eV
E/∆E=3000

V. BL06
BL06 has been mainly developed for irradiation
experiments such as photochemical reaction, SR-CVD,
photo-etching, surface modification. The white radiation
beam from bending magnet is introduced to the sample
stage using a pair of mirror, whose incident angle was 3°.
The SR at BL06 sample stage had a continuous spectrum
from IR to soft x-ray, which was lower than 1 keV. A

differential pumping system can be utilized forexperiments in a gas atmosphere, which is difficult in thesoft x-ray region. A sample holder can install four pieces ofsamples at a time. By using heater set in the sample holder,
the sample can be heated from room temperature to 220C.
The temperature of sample is monitored using a Cr-Al
thermocouple mounted on the sample holder.

VI. BL07A and BL07B
This beamline was designed for the development of
new materials by SR technology. This beamline consists of
two branch lines, which are provided with an incident
beam from a 3-m undulator by switching the first mirror.
One of them is a high photon-flux beamline with amultilayered-mirror monochromator for the study of
SR-process (BL07A) and another is a high-resolution
beamline with a varied line spacing grating
monochromator for the evaluation of nano-structure
characteristics by SR-spectroscopy (BL07B). The usefulrange of emitted photons from 50 to 800 eV is covered atboth beamlines. The light source of BL07 is a 3-m lengthplanar undulator, which consists of 29 sets of permanent
magnets, a period length of which is 76 mm. The incident
beam from the undulator is provided for two branch lines
by translational switching of first mirror.

Energyrange(eV)Material

50-60
60-95

Mo/Si

90-140140-194
190-400
400-560

Mo/B4C
Ni/C

1) BL07A
The multilayered-mirror (MLM) monochromator,
which has high reflectivity in the soft X-ray region, wasinstalled at the BL07A. It consists of a switching mirror
chamber, a slit chamber, a MLM monochromator, a filter
chamber and a reaction chamber. To obtain a large photon
flux, we decided to use only first mirror (switching mirror),M0, for focusing. The MLM monochromator is designed tocover an energy range of up to about 800 eV by
combination of three kinds of mirror pairs with 4 kinds offilter. The flux deliver by this design is estimated to be
between a maximum of 1017 photons/s at 95 eV and aminimum 21014 photons/s at 300 eV for a 500 mA ring
current.

Table 6. Summary of BL07A.
Multilayer mirror
spacing
Thickness number of
Ratio
layers
20 nm
11 nm
5 nm

0.8

20

0.5

25

0.5

60

550-800

6E/E

Filtermaterial thickness
Al

100 nm

None



Ag

100 nmCr

500 nmNi

500 nm

6.2 %
3.3 %
2.5 %

focusing mirror (M2). The monochromator is designed tocover the energy range 50-800 eV with three gratings, ofwhich including angle are 168. The VLSPG has been wellknown to obtain high resolution in extreme ultraviolet
region by diminishing various kinds of aberration. The
total resolving power about 3000 can be realized in thewhole energy region.

2) BL07B
The constant-deviation monochromator consisting of ademagnifying spherical mirror and varied line spacing
plane grating (VLSPG), which can provide to highresolution, simple wavelength scanning with fixed slits,
was mounted on BL07B. The optical system consists of afirst mirror (M0), a entrance slit (S1), a premirror (M1),and three kinds of plane grating (G), an exit slit (S2) and a

Table 7. Monocromator specification
Mount type
Hettrick-Underwood type
Grating G1, G2, G3
Plane VLS (600 l/mm, 1200 l/mm, 2400 l/mm)
Energy range
50-150 eV, 150 – 300 eV, 300-800 eVResolving power (E/∆E)～3000
VII. BL9A purpose of this beamline is studies on a soft x-ray
interferometry or a holographic exposure experiment withmaking use of highly brilliant and coherent photon beams
radiated from 11 m long undulator in NewSUBARU.
BL09 consists of M0 mirror, M1 mirror, G grating andM2 and M3 mirror. M0 and M3 mirrors are used forhorizontal deflection and beam convergence, M1 is usedfor vertical beam convergence at the exit slit, and M2 isused for vertical deflection and beam convergence. A
monochromator is constructed by M1 and a plane grating.
The maximum acceptance of the undulator beam is 0.64
mrad in horizontal and 0.27 mrad in vertical. The

acceptance can be restricted by 4-jaw slits equipped at
upstream of the M0 mirror.
BL09B beamline branched from BL09 beamline for theusage of the EUV interference lithography for theevaluation of the exposure characteristics of EUV resist.
Coherence length of 1 mm at the resist exposure position
was achieved using BL09B beamilne. And BL09C
beamline branched from BL09B beamline for the usage ofthe thickness measurement of the carbon contamination
originated to the resist outgassing during the EUV
exposure.

Table 8. Monochromator specification
Mount type
Hettrick-Underwood type
Grating
Plane VLS (900 l/mm)
Energy range
50 – 600 eVResolving power (E/∆E)～3000
VIII. BL10
BL10 is for the global use in the Himeji Institute ofTechnology. M0 mirror is used for horizontal deflection andbeam convergence, M1 is used for vertical beam
convergence at the exit slit, and M2 is used for verticaldeflection and beam convergence. A monochromator isconstructed by M1 and a plane grating. At the beginning,the multiplayers reflectiveity measurement was carried out
at this beamline. The characteristics of this beamline andthe result of the Mo/Si multiplayers measurement are
carried out for the development of the EUVL mask
techmology.
BL10 utilizes a monochromator of the varied line

spacing plane grating monochromator (VLS-PGM). Theline density of the monochromator in central region of thegrating is 600 lines/mm. The reflectometer is a two axis
vacuum goniometer using two Huber goniometers. One
axis carries the sample, which may for examplee be amirror at the center of the reflectometer vacuum tank(-motion). The other (-motion) carries the detector on arotating arm. In addition there are through-cacuum linear
motions to translate the sample in two orthogonal directions(x,y). All motors are controlled by computer. The sample
itself is mounted on a kinematic holder. The controlstage
monochromator rotation, and data analysis were program

7

using LABVIEW software. The reflectivity result obtainedat BL10 has a good agreement with that at LBNL.

Table 9. Monochromator specification
Mount type
Hettrick-Underwood type
Grating
Plane VLS (600 l/mm)
Energy range
50 – 600 eVResolving power (E/∆E)～1000
IX. BL11
A beam line BL11 is constructed for exposure Hard
X-ray Lithography (DXL) in the LIGA (German acronym
for Lithographite Galvanoformung and Abformung)process. LIGA process, that utilizes a useful industrial
application of SR, is one of the promising technologies forfabrication of extremely tall three-dimensional
microstructures with a large aspect ratio. This process wasinvented at the Institut Fur Mikrostrukturtechnik (IMT) of
the Karlstuhe Nuclear Center (KfK) in 1980.
Microstructures with height of over a few hundreds µm
have been widely applied to various fields such as
micro-mechanics, micro-optics, sensor and actuator
technology, chemical, medical and biological engineering,and so on. This beam line was designed by the criteria ;photon energy range 4 keV to 6 keV, a beam spot size on
the exposure stage  505 mm2, a density of total
irradiated photons  1011 photons/cm2. BL11 of anabsorber chamber, a first-mirror chamber (M1), a
second-mirror chamber (M2), a 4-way slit chamber, a Be
window chamber, and an exposure chamber. The second
pre-mirror is bent elliptically using a bending mechanism.

Fine bending adjustment of the M2 mirror can be made in
the UHV by the pulse motor. The LIGA process needs thephoton energies of 3 keV to 6 keV, the optics of a LIGA
beam line generally employ a Pt monolayered-mirror anda Be window, which cuts off low-energy photons. The
reflectivity of a Pt-coated mirror is about 55 % in therange of photon energy from 2 keV to 4 keV, however, it
drops to 30 % at the photon energy of 6 keV. Therefore,
new materials with a high reflectivity must to be found for
Deep X-ray lithography (DXL) in this energy range. We
propose the use of a Ni/W/C multilayered-mirror with agraded d-spacing in the range of photon energy from 3 eV
to 6 keV. The calculated reflectivity of the Ni/W/C
multilayered-mirror is higher than 56 % at the photon
energy of 6 keV with a glazing incident angle of 0.8
degrees, and photons that have higher photon energy than
6 keV can be removed A 200 µm-thick beryllium (Be)window in a Be window chamber is used to separate theultra-high vacuum part from the low vacuum part and to
cut off low-energy photons.

Table 10. Specification of the LIGA exposure system
Exposure method
Proximity exposure
Wafer size
4 inch50 mm(H)×80 mm(V)
Exposure area
Exposure environment< 1atm (He-gas)

8

Center for EUV Lithography
Takeo Watanabe and Hiroo Kinoshita
Center for EUV Lithography,
Laboratory of Advanced Science and Technology for Industry, University of Hyogo

1.

Overview of CELLaboratory of Advanced Science and Technology for Industry, University of Hyogo was established in 1995.
EUVL Lithography development has been carried out since 1995 in University of Hyogo. Especially, utilizing
the full field exposure tool which we developed, for the first time in the world, hp 40 nm resist fine pattern was
replicated with collaborating with ASET in 2000. Following this, in 2001, it was reported that hp 39 nm resist
pattern was replicated by EUV-LLC in USA. Related to these results, Dr. Gordon Moore from Intel Corporation
decided to employ EUVL technology to apply in the high volume manufacturing (HVM) for the advanced
semiconductor devices. Then after, the exposure tools have been developed by the stepper companies, andsimultaneously the development of masks and resists have been carried out
Since 2006, Semiconductor Leading Edge Technologies (Selete) which receives a mandate to develop an
EUVL technology from New Energy and Industrial Technology Development Organization (NEDO) has been
investigated to develop exposure tools such as SFET and EUV1 for the development of the semiconductor
devices. As results, it was concluded that “there is no obstacle to develop EUVL technology for 32 nm node”,
and investigation program will finish in the end of March in 2010.
In our laboratory, concerning of the mask technology, EUV microscope was developed for the mask defectinspection from 2002 to 2007 by the funding from Core Research for Evolutional Science and Technology(CREST), Japan Science Technology Agency (JST). EUV microscope (EUVM) which is only one tool in theworld is placed to use for the mask inspection of the absorber pattern and the mask blanks, and we obtained
many results in collaborating with Selete. In addition, since 2008 for the mask inspection for 22 nm node andbelow, lense-less inspection tool on the basis of EUV coherent scattrometry has been developing in collaboratingwith RIKEN and Osaka University in the CREST program.
Furthermore, concerning of the resist, outgas evaluation during EUV irradiation has been carried out since
2000, and many scientific knowledge was obtained. Recently, the in-situ carbon contamination in the resist
outgas environment by EUV irradiation has been carried out. And for the resist evaluation in 22 nm and 16 nm
nodes, it is certain that EUV interference lithographic tool which we developed has a capability to replicate hp16nm resist pattern.
The market shares of the Japanese company supplying masks and resists for EUVL are high, such as 100% for
the mask and 70% for the resists, respectively. Taking these shares into consideration, since useful equipments
which we have developed in NewSUBARU for the advanced semiconductor devices using an EUVL technology
can be opened for common use, we hope strongly that many companies could use the equipments. Consequently,
it is consider that University of Hyogo can play a significant part of the development for the advanced
semiconductor devices.
As results, “Center for EUV Lithography” is established, and use of NewSUBARU in EUVL technology is
promoted. In addition, the experienced researchers from outside will be invited as a guest researcher of thiscenter, and we will make efforts to receive the user’s comments and requirements to support the EUV
lithographic technology for the practical use.

9

2. The Outline of the beamlines for EUVLThe exposure and evaluation experiments related EUVL are carried out at BL-3, BL-9 and BL-10 beamlinesof the NewSUBARU synchrotron radiation facility in Center for EUV Lithography.
BL-3 (bending magnet as a light sourc): EUV microscope (EUVM) and EUV coherent scattrometry
micropscope (CSM) are installed in this beamiline. EUVM is developed for absorber pattern inpspection for the
EUV finishied mask. CSM is developed for the phase defect inspection of the mask blanks and continously
developing it to achievce more higher resolution in inspection.

IL Exp. tool

EUV IL Beamline

BL-9 (10.8-m-long undulator as a light source): Since monochrometer is installed at the middle of this beamline, high accurate spectroscopic measurement is available using the undulator and the monochrometer.
Especially, EUV interfrence lithograpic exposure system is installed in the clean room at the end of this beamline.
Furthermore, in the additional bemaline which is seperated from the original one, resist outgas evaluation system
and in-situ thickness measuement system for the carbon contamination adhesion under the similar light intensityof the HVM EUV exposure system.
BL-10 (bending magnet as a light source): Since two monochrometers of 600/mm and 1800/mm are installedat the middle of the beamline, a high accurate reflectivity measurement for the optical element such as multilayer
mask is available using this beamline. In addition, the optical constants measurement utilizing the vacuum
chamber for common use is carrying out. In the future, refelctivity measurement of the illumination optics,
multilayer charactreization evaluation, and multilayer evalution using polarized light are planned to use theBL10 beamline.

10Study on High Brightness Operation of NewSUBARU
without RF Shaker
Satoshi Hashimoto, Sayaka Chin and Shuji Miyamoto
LASTI, University of Hyogo
Abstract
We studied the possibility of the high brightness operation of the NewSUBARU electron storage
ring without lattice modification. By turning-off the RF shaker that is used to enlarge the verticalsize and the lifetime of stored electron beams, the brightness can be improved 2.7 times assumingthat the stored current is the same. As the lifetime decreases, the top-up current is also reduced
due to the limitation for the total charge that can be injected to the ring. Using a top-up simulator,
we found that the brightness improvement factor could be 1.6 including the stored current decrease
effect.
Introduction
Beam lifetime of the NewSUBARU electron storage ring is dominated mainly by the Touschek effect at
1.0 GeV operation. The industrial users in our radiation facility such as EUVL lithography and LIGA havebeen performed irradiation experiments and prefer the beam operation with a long beam lifetime and an hightop-up current more than that with an high brightness. To improve the lifetime the ring has been operated
with intentionally enlarged vertical beam size using RF shaker, where amplified white-noise signal is added
to four strip-line electrodes to vertically shake electron beams, and now we achieved the lifetime of 7.4 hrs at
the top-up operation of 220mA.
Recently, increasing number of industrial analysis users in our facility want the high resolution ofsynchrotron radiation and the high brightness operation. Generally speaking, the high brightness operationof storage rings needs re-design of ring lattice and re-arrangement of magnets and vacuum chambers and soon. However, in case of NewSUBARU, there is room for making the brightness higher by an easy way, thatis, the operation without RF shaker.
Laws and regulations on radiation safety restrict the total charge that can be injected from a linac to ourring per eight hours (one shift). This fact means that the reduced beam lifetime causes the reduction of the
top-up current that should be kept constant for eight hours. It is important to evaluate how much thebrightness is improved and how much top-up current is reduced by turning-off RF shaker.
Measurement of Lifetime and Beam Size
The total beam lifetime  is determined by the Touschek lifetime  Tous and the gas scattering
lifetime  gas; 1/  =1/  Tous + 1/  gas. We measured the dependence of the lifetime on RF shaker power asshown in Fig. 1. The inverse lifetime increases according to the inverse square root of the RF shaker power.
Turning-off RF shaker, the lifetime was reduced to 2.1 hrs. The vertical size of electron beams was alsomeasured using a visibility monitor [1]. As shown in Fig. 2, the vertical beam size increases according to
the square root of shaker power, that is, kick strength. From these data, we found that 1/  =0.664 / W +1/  gas, and  gas is about 470 hrs at 1.0Gev, 220 mA.

Fig.1. Lifetime vs. RF shaker power

Fig.2. Vertical beam size vs. RF shaker power

Improved Brightness Estimated by Calculation
The brightness of synchrotron radiation is given by

11

(Brightness)  (Photon Flux) / (source dimensions) / (angular spreads of source).
Following the above relation, the reductions of dimension and angular spread of a photon source makes thebrightness higher. We evaluated equivalent reduction of vertical emittance by turning-off of RF shaker andcalculated the improved brightness using the above equation and SRW [2]. Calculated results show that thebrightness could be improved 2.7 times in case of the same stored current by turning-off RF shaker as shownin Fig. 3.

Fig.3. Calculated improvement of brightness .

Fig. 4. Beam accumulation andtop-up operation in a day

Estimation of the Reduced Top-up Current using Top-up Simulator
The reduced beam size causes the reduction of the Touschek lifetime and the possible top-up current. To
evaluate the maximum top-up current, we developed the top-up simulator [3] that can simulate beam
accumulation and top-up operation including various effects such as injection beam intensity, injection
efficiency and lifetime and so on. Beam accumulation and top-up operation in a typical day is shown in Fig.
4. In our facility a beam accumulation starts at 9 a.m. and if the stored current reaches 220mA the top-up
operation for user time starts. The amount of injected charge is measured at a beam transport line. If theintegrated charge exceeds the limit in one shift (369nC), the safety interlock system stops beam injections.
The integrated value is reset at 8:30, 16:30 and 0:30.
The results of simulation are in good agreement with the realistic operation. Using this simulator, wefound that the maximum top-up current is 135mA in the case of turning-off RF shaker. In other words, theoperation over 135mA can’t keep the top-up current constant until reset time of 14:30.
Considerations
By turning-off RF shaker, the brightness atthe same current increases, but the maximum
top-up current decreases. The brightness
improvement factor including the current
reduction effect is shown in Fig. 5. From
this figure we found that it is possible to makethe brightness 1.6 times higher by simply
turning-off RF shaker.
The high brightness operation without RF
shaker could be one of operation modes in
NewSUBARU, if users require the radiation
with higher quality in our facility.
Fig.5.

Brightness improvement factor

Acknowledgements
We greatly thanks to Dr. T. Harada of LASTI for his cooperation, especially offering the spectrum data of
BL9 and BL10 in NewSUBARU.
References[1] S. Hashimoto et al., LASTI Annual Report, vol. 5, pp.13-14 (2003).
[2] http://www.esrf.eu/Accelerators/Groups/InsertionDevices/Software/SRW[3] S. Chin, Bachelor thesis, University of Hyogo (2010)12

RESEARCH ACTIVITIESUpgrade Plan of 15MeV Compact Electron Linear
Accelerator LEENA as a Terahertz Radiation Source
Satoshi Hashimoto, Sayaka Chin, Dazhi Li#, Sho Amano and Shuji Miyamoto
LASTI, University of Hyogo#
Institute of Laser Technology
Abstract
We are planning to upgrade the 15MeV electron linear accelerator LEENA as a radiation source interahertz regime. For the precise beam handling, an old-fashioned control system is now partially
updated to the new one based on PC and Linux. Upgrade of other components such as beam
monitors, RF low-level system, and terahertz radiation monitoring system are also being planed.
Beam commissioning for the generation of terahertz light by Smith-Purcell radiation has started.
Introduction
Apart from 1.5GeV electron storage ring, we have a 15MeV electron linear accelerator LEENA [1] in the
NewSUBARU facility. This compact linac was constructed prior to the NewSUBARU ring, and studies onfree electron laser in IR regime and the generation of bright beam using needle cathodes have been
performed [2]. The aging machine has an old-fashioned control system and its performance was poor.
Thus we planed the upgrade of LEENA accelerator as a terahertz radiation source and some parts of this plan
are underway.
Generation of terahertz radiation and its application are recently becoming more interesting. In addition
to UV, soft X-ray and Compton gamma ray from NewSUBARU, the terahertz light form LEENA will further
promote the industrial application of various kind of radiation in our facility.
General layout of the 15MeV Linac LEENA
Figure 1 shows the general layout of LEENA.
Electron beams generated by a RF gun with a thermalcathode are bunched at an alpha magnet andaccelerated up to 6-15MeV. After passing through adispersive section, electron beams go to a radiationchamber. Then the beams are dumped after being
deflected by a bending magnet. Main parameters of
LEENA are shown in Table. I.

Table I Main parameters of LEENA
RF frequency
2856 MHz
Beam Energy
6-15MeV
Energy spread+-0.5%@15MeV
Micro pulse
peak current
50A
Pulse width<10ps
Macro pulse
Frequency
1-10HzPulse width
10us

Fig.1. Layout of LEENA accelerator

13

Upgrade of Accelerator Control System
The control system of LEENA was based on PLC (Programmable Logic Controller). Magnet currents
and RF parameters were adjusted by potentiometers or from a touch panel. Thus it was difficult to precisely
control these parameters and the reproducibility was poor.
We are developing the new control system that is based on LabVIEW and EPICS [3] and can be flexibly
controlled from Windows or Linux machines. Three PC or Linux machines are running as virtual machines(VMs) in VMware server on a Linux host machine. Operation programs for controlling devices run overthe VMs. Client machines access to the VMs through the dedicated network for LEENA. Any kind of
devices for LEENA, including PLC, oscilloscopes, GPIB-Ethernet converters, and network-distributed
devices, is connected to this private LAN. PLC (Mitsubishi MELSEC Q-series) is already connected to
LabVIEW via OPC server and we are developing several control programs with a graphical user interface.
Main program controlling LEENA will be developed with EPICS.

Fig. 2. New control system for LEENA
Other Upgrades
In addition to the control system, the following system upgrades are planning or underway.
Present beam monitor system is composed from six current transformers (CT) and four screen monitors.
In addition to these monitor, beam position monitors (BPM) are necessary for precise control of the beam
trajectory and a few will be installed. The shape and length of electron bunches play important roles ingenerating terahertz radiation. Development of a bunch length monitor using both the electro-opticaldetection of Coulomb field and the single-shot cross-correlation of optical pulses [4] is desired.
One of the most important problems to be solved is the beam loss at beam transport. It is necessary for
reducing the beam loss not only to precisely control magnet and RF parameters, but also to study beam
dynamics using simulation code such as GPT [5]. Another important problem is the beam stability.
Present unstable operation may come from poor controls of RF low level and utilities such as cooling water.
The new control system based on PC is useful to a feedback control of these quantities.
As for measurement of terahertz radiation, monitor systems of power and spectrum are underconstruction.
Generation of Terahertz Light
Three radiation sources may be possible for the generation of terahertz light with LEENA; (1)Smith-Purcell (SP) radiation, (2) coherent synchrotron radiation from a bending magnet with bunchedelectron beams, (3) free electron laser in terahertz regime.
SP radiation is generated when an electron beam passes close to the surface of a periodic structure, that is,a diffraction grating. In LEENA a diffraction grating has been installed and beam commissioning operation
started in April 2011. In addition to the conventional SP radiation, observation of coherent SP andsuperradiant SP radiations [6] are expected.
Acknowledgement
We greatly thanks to Mr. Kawata, Mr. Takemura and Dr. Minagawa for their cooperation.
References[1] http://www.lasti.u-hyogo.ac.jp/NS-en/facility/leena/[2] T. Inoue et al., Jpn. J Appl. Phys., 41, pp.7402-7406 (2002).
[3] http://www.aps.anl.gov/epics/index.php[4] B. Berden et al., Proceedings of EPAC2004, pp.2700 (2004)[5] http://www.pulsar.nl/[6] D. Li et al., Phys. Rev. ST AB, 9, 040701 (2006)14

Photonuclear reaction of iodine-129
with laser-Compton scattering gamma-ray
Ken Horikawa
LASTI, University of Hyogo
Abstract
A photonuclear reaction cross section of iodine-129 was measured using a polarized laser-Compton scattering gamma-ray beam in an energy range from 13.9 to 19.7 MeV. The maximum cross section was evaluated to be 220 mbarn ±50% at a photon energy of 15.9 MeV ±4%. We
did not observe any appreciable difference in the cross sections for linearly and circularly polarized gamma-ray beams, considering the limits of experimental error.
Introduction
We previously proposed the nuclear transmutationof radioactive nuclei including iodine-129 using alaser-Compton scattering (LCS) gamma-ray beam1).
To evaluate the process efficiency, we must have an
accurate photonuclear reaction cross section ofiodine-129. J. Magill et al.2) measured an integral
cross section of iodine-129 R by laser-generated
bremsstrahlung photons that had a Boltzmann-like
distribution with a hot-electron temperature withrandom polarizations. They assumed a Lorentzian
shape for R with a calculated energy threshold of 8.8
MeV and Emax = 12.4 MeV, and obtained a cross section of R(Emax) = 220 mbarn2), where Emax is thephoton energy which maximizes the R and R(Emax)
is the R at Emax. Unfortunately, their measurement
was only accurate within a factor of two. In addition,
the gamma-ray-polarization dependence of the crosssection has not been investigated yet. For this study,
we carried out measurements at NewSUBARU todetermine the dependence of the photonuclear reaction cross section of iodine-129 on the energy andpolarization of incident gamma-ray photons.

to be 36.8 kBq by Isotope Products Laboratories5).
The number of iodine-129 atoms in the target wascalculated to be 2.63 × 1019 from its radioactivity of
36.8 kBq and the half-life of iodine-129 I-129 = 1.57
× 107 year6).
The number of iodine-128 atoms N(t) is derived
as a function of time from the following equation:
Y(1)
N(t)  1  e  λt .
λwhere Y is the yield rate of iodine-128,  =ln 2 τ I 128 = 0.028 min−1 is the decay rate coefficient, which is constant, and I-128 = 25 min is thehalf-life of iodine-1286). After the irradiation of the
gamma-rays, the number of decayed gamma-rays
with an energy of 443 keV, which were emitted fromthe radioactive iodine-128, was measured using a Ge
detector. The peak detection efficiency of the Ge detector used in this experiment was calibrated to be
5% using the 384-keV gamma-ray photons emitted
by barium-133. The probability of one iodine-128
atom emitting a 443-keV photon in a spontaneous
decay process was considered to be 12.6%6). The
number of iodine-128 atoms Ni was calculated using
the following equation:
NT
Ni 
,
(2)
1  e  λT
where NT is a number of decayed iodine-128 atoms
and T is a time period for measuring the 443-keV
photons.

Experimental
Polarized gamma-rays with maximum energy of
16.7 MeV were generated in the storage ring by theinteraction between a 1.064-m CW laser beam of
4.6 W and a 974 MeV electron beam of 220 mA. The
laser polarization was rotated using a combination of
/4 and /2 wave plates in a laser oscillator. The polarized gamma-rays were semi- monochromatized inthe 3% energy spread using a 3-mm-diameter leadcollimator. The flux of the gamma-rays incident on
the target was measured using a 10-mm-thick plastic
scintillator that was installed in front of the target.
The scintillator was attached with a 1-mm-thick pieceof lead as a signal multiplier on the beam incident
side. The flux of the polarized and semi- monochromatized gamma-rays was measured to be 5 × 105
photons sec−1 3). The polarization of the gamma-rays
was measured4) and confirmed to be controllable by
the polarization of the incident laser beam.
Iodine-129 was prepared as a powder of palladous
iodide. The radioactivity of the target was calibrated



Derivation of reaction cross section
The photonuclear reaction cross section ofiodine-129 R was evaluated as follows using Ni [Eq.
(2)]. The variation of the yield rate of iodine-128 dY
for distance dx along the direction of the LCS gamma-ray beam is expressed as follows:dY  n  f(x)  σ R  dx  dS ,(3)
where n is the atomic density of iodine-129 and f(x) is
the flux of the gamma-ray photons per unit area atposition x. The atomic density was calculated to be
7.4 × 1017 mm−3 from the size of the target. The
3-mm-diameter collimator passes an axial portion of
the incident gamma-ray beam so that the spatial distribution of the transmitted beam with a 3-mm di-15

ameter is uniform, and the target has rotational symmetry whose axis is coaxial with the beam axis. By
evaluating Eq. (4), Y is described as follows:Re  n σ  σ x dx dr ,R

S

Cross section (mbarn)

L r 

Y  2π  n  σ R  f 0 0 r 0

350

(4)

where f(0) is the value of the incident flux at the target entrance. f(0) was measured as f(0) = 4.7 × 104
photon mm-2 sec−1 ± 2%. R is the radius of the target,
L(r) is the penetration distance of the incident gamma-rays into the target, which is a function of radius r.
S is the cross section for all processes except thephotonuclear reaction.

300
250
200
150
100
50
0

Dependence of reaction cross section on polarization and energy of incident gamma-rays
Fig. 1 shows photonuclear reaction cross section
R derived from Eqs. (1) and (4) by assuming thevalue of S proposed by J. Berger et al.7) in an energy
range from 13.9 to 19.7 MeV for both linear(crossed) and circular (circled) polarizations of incident gamma-rays. The gamma-ray photon energy wasscanned by changing the energy of the electron beamfrom 890 to 1060 MeV. The probability distributionof the signal intensity against the count rate was assumed to be a Poisson distribution. From its standard
deviation, the error bars in Fig. 1 were calculated tobe 12% at respective gamma-ray energy. The error in
the absolute value of the cross section was evaluatedto be ±50% by taking into account the errors due tothe alignment accuracy between the gamma-ray beamand the target axes; this accuracy was a major factor
compared with the errors in the number of iodine-129
atoms (< ±1%), the flux of the gamma-rays (±2%),
their energy spread (-3%), and the peak detection
efficiency of the Ge detector (±10%).
An appreciable difference in the cross sections
determined for linear and circular polarizations was
not observed because the data of both polarizations
remained within the dispersion of the measurements.
Therefore, all data of the cross section of theiodine-129 target were treated as a set and fitted by a
Lorentzian curve to derive the dependence of thecross section on the photon energy8). From the above
evaluation, the energy dependence of the cross section was determined by a fitting curve with a maximum value of 220 mbarn ±50% at 15.9 MeV ±4%
with a half-width at half-maximum of 2.55 MeV±20%. In this measurement the accuracy of the crosssection obtained was improved compared with that ofthe data by J. Magill et al.2) because the polarized
gamma-rays were semi- monochromatized in the 3%energy spread so that the cross section was directly
obtained for each energy point of the gamma-ray
photon. The photon energy dependence of theiodine-129 R was obtained experimentally by scanning the energy of the semi- monochromatized gamma-ray photons.
The (, n) reaction is caused by the giant resonance which is due to the gamma-ray photon field in
nucleus. No appreciable difference observed in the8

10 12 14 16 18 20
Photon energy (MeV)

22

linear-polarizedcircular-polarized
Fitting curve @ LorentzianFig. 1 Dependence of photonuclear reaction crosssection of iodine-129 on energy and polarization of gamma-ray photons.

cross sections determined for linear and circular polarizations suggests that the helicity of the photon due
to the polarization does not affect the photon reaction
by the giant resonance. The theoretical analysis toexplain the above result will be done in further study.
Conclusion
We determined the maximum photonuclear reaction cross section of iodine-129 to be 220 mbarn±50% at a photon energy of 15.9 MeV ±4% with ahalf-width at half-maximum of 2.55 MeV ±20%. We
did not observe any appreciable difference in the
cross sections determined for linearly and circularly
polarized gamma-ray beams considering the limits ofexperimental error.
Reference[1] K. Imasaki et al.: Proc. SPIE Advanced HighPower Lasers and Applications ’99, Osaka Japan,
1999, pp.721 (2000).
[2] J. Magill et al.: Appl. Phys. B, 77, pp.387 (2003).
[3] K. Horikawa et al.: Nucl. Instr. and Meth. A, 618,
pp.209 (2010).
[4] Nobuhiko Sakai et al.: submitted in Nucl. Instr.
and Meth. A.
[5] Isotope Products Laboratories. Eckert & Ziegler
Isotope Products (Main Office) 24937 Avenue Tibbitts Valencia, CA 91355.
[6] Jagdish K. Tuli: “Nuclear Decay Data in the
MIRD Format,”<http://www.nndc.bnl.gov/mird/> (2010).
[7] M. J. Berger et al.: “XCOM: Photon Cross Sections Database,”<http://www.nist.gov/pml/data/xcom/index.cfm>(2010).
[8] R. L. Bramblett et al.: Phys. Rev, 148, pp.1198(1966).

16

Determination of the number of pulsed laser-Compton
scattering photons
Takeo Kondo1, Hiroaki Utsunomiya1, Hidetoshi Akimune1, Tamio Yamagata1, Akiyuki Okamoto1, Hideo
Harada2, Fumito Kitatani2, Tatsushi Shima3, Ken Horikawa4, Shuji Miyamoto4
1Department of Physics, Konan University 2JAEA 3RCNP, Osaka University 4LASTI, University of Hyogo
Abstract
We measured pulse-height spectra of 16.7 MeV laser-Compton scattering photons with a 6” × 5”
NaI(Tl) detector for a blank and three lead materials of 75.8, 50.9, and 25.9 % transmissions at the
NewSUBARU facility to investigate how the original Poisson distribution of the pulsed photons is
modified after passing through thick-target materials. We present a well- prescribed method ofdetermining the number of incident photons within 3.5% accuracy based on the response of the
NaI(Tl) detector to the pulsed photon beams.
1. Introduction
Quasi-monochromatic γ-ray beams are producedin the interaction of laser photons with relativistic
electrons, which is referred to as inverse Comp- tonscattering, at synchrotron radiation facilities inJapan[1, 2], where the laser-Compton scattering(LCS) γ -ray beam is used in nuclear physics
experiments. An experimental study of photoninduced nuclear reactions requires a thick target
material because of small interaction cross sections.
Therefore, the determination of the number ofphotons incident on the target material is an important
experimental factor,
Collisions of pulsed laser photons with relativistic
electrons in a storage ring are a statisticalphenomenon. Thus, the probability distribution of thenumber of scattered photons n is expected to follow
the binomial distribution. Since the product of thenumbers of laser photons and electrons, N, involvedin each laser pulse is very large and the collision
probability p is very small, the binomial distribution
may be reduced to a Poisson distribution[3]distribution[4]. Thus, it is straightforward to deduce
the number of LCS photons if the average number ofscattered photons per laser pulse, m, is experimentally
determined. In measurements with a thick target, thePoisson distribution is modified by attenuation ofpulsed LCS photons in the target material. How- ever,
it is readily shown that the modified distribution
remains a Poisson distribution with a different valueof the average number of scattered pho- tons m′. Also
shown is that the number of LCS photons incident on
the target can be deduced if m′ is corrected for theattenuation by a factor α(2)with α = e−µt, where µ is the linear attenuation
coefficient of γ rays and t is the thickness of target
material.
We experimentally tested this prescription for
determining the photon flux using thick lead materialsof different thicknesses and verified the prescription.
We report results of the experimental test and present
an experimental formula for the photon flux
determination which is useful in a thick target
measurement.

(1)where m is the average number of scattered photons
per laser pulse which is given by m = Np.
Previously it was shown that energy spectra ofpulsed LCS photon beams measured with a BGO
detector are characterized by the Poisson

2. Experiment
We produced a 16.7 MeV pulsed quaimonochromatic γ-ray beam in the laser-Compton
scattering of 1064 nm laser photons from 974 MeV
electrons at the NewSUBARU facility. The quoted γray energy stands for the maximum energy. A top-up

Central region of
the laser"Compton scattering

e"

eam

Experimental hatch

nb

ro
ect

El

Wall

LCS Γ "rayNaI!Tl" detector
TargetPb collimator

Vacuum duct

Laser

MirrorMirrorFig. 1: Experimental setup in the LCS γ-ray production beam line at the NewSUBARU facility.
Figure 1: (Color online) Experimental setup in the LCS -ray production beam line at
the NEWSUBARU facility.

17

at the NEWSUBARU facility. The quoted -ray energy stands for the maximum energy. A top-up operation of the storage ring was carried out, where! 104
4"a# Blank

Pile upCalculation
Single Photon

3
2
1

0

6

"b# Pb "Α # 75.8 %#4Counts!Channel

operation of the storage ring was carried out, where
electrons are injected from a linear accelerator
whenever a decrease of the electron beam current
beyond a threshold is detected. The top-up opera- tion
kept the beam current constant at 219.98 ± 0.44 mA(0.2 % variation) during the present measurement.
The experimental setup is depicted in Fig. 1. Laser
photons from a YVO4 laser operated in a Q-switch
mode at 30 kHz were injected into a 20 m straightsection of a storage ring of race-track shape. A 3 mm
lead collimator of 100 mm thickness was mounted ina small experimental hatch at the distance of 16.49 mfrom the central region of the laser-Compton
scattering. Three natural lead targets of 4.4, 10.6, 21.2mm thicknesses were used. The transmission rate of
the three targets is 75.8, 50.9, and 25.9 %,respectively [5]. The target was mounted immediately
upstream the collimator. A NaI(Tl) detector of 6 in.
diameter and 5 in. length (REXON components inc.,USA) was mounted at 30 cm downstream thecollimator to measure the 16.7 MeV LCS γ-ray beam.
Measurements at 3.94 W laser power were carried out
for 600 sec to obtain energy specc- tra of the pulsed
LCS photon beam for the three lead targets and ablank target. Single-photon spectra were alsomeasured for 300 sec at a reduced laser power 0.10
W in the blank- and lead-target runs. We note that
14.2 % of the 16.7 MeV photons transmit the NaI(Tl)detector. However, this transmission does notessentially affect the discussion made below.

20
10"c# Pb "Α # 50.9 %#

5

0

10

"d# Pb "Α # 25.9 %#50Probability!Channel

3. Results and analysis
2000
1500
1000
500
0
Figure 2 shows multi-photon pile-up spectra hp(x)Channel Number
measured for a blank target and the three lead targets.
Fig. 2: Experimental pile-up spectra of a 16.7
Single-photon spectra hs(x) measured for each target
MeVExperimental
LCS γ-ray beammeasured
withofthe
× 5”
Figure2:(Coloronline)pile-upspectraa 6”
16.7
MeV LCS -ray beam
are also shown in the figure. Obviously the result for a
detectordetector
for a blankand (a)threemeasuredwith the 6”NaI(Tl)
5” NaI(Tl)for a(a)blankandleadthree lead targets wit
blank target (Fig. 2(a)) represents a pile-up
spectrumtargets% (b),
50.9 % (c),rates,and 25.9%of the LCS γ-ray beam originally producedin the75.8 % (b),50.9 % (c),andwith
25.975.8% (d)transmission
respectively.
Experimenta(d)transmission
rates,
respectively.
Experimental
interaction between laser photons andrelativisticspectra are shown by the dashed lines in an arbitrary scale. Best fits to th
single-photon
spectra are shown by the dashedelectrons. One can see in Figs. 2(b), 2(c)and 2(d) thatpile-up single-photon
experimental
spectra are shown by the dotted lines (see text).
lines in an arbitrary scale. Best fits to thethe pile-up spectra vary when the γ-ray beam passes
experimental pile-up spectra are shown by thethrough the lead targets in such a way that the center
dotted lines.
of gravity of the distribution is shifted toward lessmultiplicity with increasing the target thickness! 10"3(decreasing the transmission rate). This is obviously
n#1
because of the attenuation of the LCS γ rays in the
1.5
target materials.
5
The NaI(Tl) detector responds differently when it
detects n photons with each having 16.7 MeV and aphoton with 16.7 × n MeV. The response to multiple
1.0
2
photons with the multiplicity n with each having 16.7
MeV, Rn(x), was calculated from the experimental
3
single-photon spectrum, R1(x), by
4
0.5

5

6 7

8 9 10where.
The resultant multiple-photon spectra are shown in
0Fig. 3 for n= 2-10 as well as the single-photon spectra
0
500
1000
1500
2000
(n=1).
Channel Number
In Fig. 4, we compare the peak position of theexperimental pile-up spectrum corresponding to theFig.
3: Themultiple-photon
distributions
with
Figure 3: (Color
online)The multiple-photon
distributions
with themultiplicity n (n=multiplicity n (solid circles) with the calculation 1-10)(opencalculatedthe
fromthe experimental
single-photon
distribution(seethetext).
multiplicity
n (n=1-10) calculated
fromcircles) for the blank and three Pb targets. It is noted
experimental single-photon distribution (seethat the n=1 peak positions of the pile-up spectratext).

N (n) = No Pm (n),(3)

with Pm (n) given by Eq. (1). Note that No represents the number of photon
beam pulses and n is the number of photons involved in a beam pulse. When18n photons per beam pulse are incident on a target material with a transmission rate , the probability that n0 photons pass through the target is given00
by C 0 ⇥ n ⇥ (1)n n . Therefore, the multi-photon distribution is1500!a" Blank! 106

4 !a" Blank

1000

3

ExperimentCalculation

500
0

1500

2

!b" Pb !Α " 75.8 %"

1

1000

4

500

3

0

1500

!c" Pb !Α " 50.9 %"Photon yields yn

Peak Channel Number

5

1000
500
0

1500

!d" Pb !Α " 25.9 %"!b" Pb !Α # 75.8 %"2
1
6!c" Pb !Α # 50.9 %"

5

4

3
2
1

1000

8 !d" Pb !Α # 25.9 %"7Experiment
6
Poisson Distribution
Calculation
5
1 2 3 4 5 6 7 8 9 104Multiplicity n
3Fig. 4: The peak channels of the experimental2
pile-upcorresponding
the multiplicity(Color online)
Thespectra
peak channelsof the toexperimental
pile-up spectra corre-1

500

Figure 4:
n (filled
circles)in comparison
with withthosethoseof theof the experimental
ponding to the multiplicity
n (filled
circles)in comparison
experimental
withdistributions withingle-photon distribution
with n=1single-photon
and calculateddistribution
multiple-photon
n=2-10 (open circles).n=1 and calculated multiple-photon distributions

0

1

2

3

4

5

6

7

8

9 10

Multiplicity n

Fig. 5: The peak channels of the experimental

with n=2-10 (open circles).

Figure 5: (Color online)
Experimental
multiple-photon
eventswith n 1 (dark-tint hispile-up
spectra corresponding
to themultiplicity
togram) and best-fitn Poisson
distributions
with n with0 (light-tint
for a blank(filledcircles)incomparison
thoseofhistogram)the(solid circles) for blank and the lead target(a)with
75.8
and three lead targets
with 75.8single-photon% (b), 50.9 % (c)and 25.9 % with(d) transmission rates,
experimental
distribution% transmission are larger by 14-12 % thanthose of Multiple-photon events with n 1 for the three lead targets (half-tint hisrespectively.
n=1 and calculated multiple-photon distributions
the corresponding single- photon spectra (stars).
togram) The
calculated from those for the blank target by taking into account the attenuation
with n=2-10 (open circles).
same tendency is seen for the peak positionsoftheof the photons in the target materials.

pile-up (solid circles) and calculated (open circles)
spectra with n=2-4. This
7 discrepancy is unlikely totake place for the primary component of the NaI(Tl)scintillation light with 230 ns decay time in view ofthe 30 kHz frequency of the γ-ray beam pulses.
However it may take place for an afterglow byphosphorescence with 0.15 s decay time [6]. The
afterglow effect may be enhanced in a detection ofhigh-multiplicity photons each having 16.7 MeV.
Indeed, it has been observed in past measurementswith LCS γ-ray beams at 20 kHz at the National
Institute of Advanced Industrial Science andTechnology [1] that a discrepancy of the n=1 peak
position in single-photon and pile-up spectra increases
with increasing the average number of photons per
beam pulse. Furthermore, we note that theexperimental peak position for higher multiplicities
tends to saturate more rapidly than the calculation. We
ascribe this saturation effect to the response of thephotomultiplier tube of the NaI(Tl) detector. The
deviation observed at n=10 in blank and the Pb target
with 75.8 % transmission was 11 %.
The experimental pile-up spectra were fitted by asuperposition of the calculated multiple-photon
distributions, where corrections were made for the
dependence of the peak 8position on the multiplicity.
Best-fit results are shown by the dotted lines in Fig. 2.
Thus, the experimental pile-up spectra were
decomposed into multiple-photon events with themultiplicity n. The number of the multiple-photon
events are shown by the histogram as a function themultiplicity n in Fig. 5 for blank and the three Pbtargets. The experimental distribution of the multiplephoton events was fitted by a Poisson distribution foreach targets. The resultant Poisson distributions arealso shown in Fig. 5.
One can easily understand the experimental factthat the multi-photon distribution (the distribution of
the multiple-photon events) resulting from theattenuation of the LCS photons in the target material
remains a Poisson distribution.
Starting from the multi-photon distribution for a
blank target, we calculated those for the three Pbtargets taking their transmission rates of 75.8, 50.9
and 25.9 % into account. The results are shown by the19half-tint histogram in Fig.5. One can see that theexperimental multi-photon distributions for the threePb targets are well reproduced by the calculation.

Finally we present a more practical prescription
for a photon flux determination. Instead of the multiphoton spectra with the multiplicity n≠0 (Fig. 5), let
us deduce the number of incident LCS photons fromthe experimental pile-up spectra (Fig. 2).
The number of incident LCS photons obtained
from this practical prescription is listed in Table III.
The results obtained from blank and the three Pbtargets agree to each other within 3.5%. Naturally the
results are in excellent agreement with those given in
Table II.

Table I. The number of the LCS photons incident
on targets estimated from the Poisson distribution
with n ≥ 0 shown in Fig.5. The number of the
LCS photon-beam pulses with n ≥ 0 is given by
the product of the frequency of the laser (30 kHz)and the data acquisition time (600 s); N0=1.80 ×
107.
targetmfit 1)
Nout γ(×107) Nin γ (×107)
Blank
3.84
6.90
6.90
Pb (α=75.8%)
2.89
5.19
6.85
Pb (α=50.9%)
1.89
3.41
6.70
Pb (α=25.9%) 0.916
1.65
6.38
1) The average number of photons in the Poisson
distribution.

Table II. The number of the LCS photons
incident on targets γ estimated from theexperimental multi-photon distribution with n ≥ 1
shown in Fig. 5.
targetmexp 1) N p2)(107) Nout γ (107) Nin γ (107)
Blank
3.97
1.72
6.81
6.81
Pb (α=75.8%) 3.12
1.63
5.10
6.73
Pb (α=50.9%) 2.29
1.48
3.39
6.67
Pb (α=25.9%) 1.56
1.08
1.69
6.52
1) The average number of photons in theexperimental multi-photon distribution (Fig. 5).

4. Discussion
It is straightforward to deduce the number ofincident LCS photons, Nγ. Using the Poisson
distribution, we get Nγ＝N0m which is the average
number of photons per LCS photon-beam pulse mtimes the number of the LCS photon-beam pulses.
The number of beam pulses is equal to the frequencyof the beam pulses (30 kHz) times the data acquisition
time.
The number of incident LCS γ rays is also
obtained from the attenuated multi-photon distribution
by Nγ＝N0m= N0m'/α using the average multiplicity m'

Table III. The number of the LCS photons
incident on targets γ calculated from theexperimental pile-up spectra shown in Fig. 2.
targetmexp 1) N p2)(107) Nout γ (107) Nin γ (107)
Blank
3.97
1.73
6.87
6.87
Pb (α=75.8%) 3.14
1.66
5.21
6.88
Pb (α=50.9%) 2.33
1.49
3.48
6.84
Pb (α=25.9%) 1.59
1.08
1.72
6.65
1) The average number of photons in theexperimental pile-up spectra (Fig. 2).

for the attenuated multi-photon distribution and thetransmission probability α given by Eq.(2).
When we use the Poisson distributions that are
best fits to the experimental multi-photon
distributions, we obtain the number of the LCS
photons incident on the target materials as listed inTable I. Note that the number of the LCS photons
were in principle kept constant by the top-up
operation of the NewSUBARU storage ring. The threemeasurements with the Pb targets give results that areconsistent with that for blank target within 8 %.
In an actual experiment, a photon detector does
not detect zero multiplicity events (n=0, no photons
per beam pulse). However, the experimental multiphoton distribution can be directly used to determine
the number of incident LCS photons. The number of
LCS photons is determined from the product of theaverage number of photons per beam pulse and thenumber of beam pulses for the experimental n≠0
events. Note that the former quantity corresponds tom'/(1−e−m′) in the Poisson distribution, while the latter
quantity corresponds to N0(1−e−m′). The number ofincident LCS photons is determined by correcting forthe attenuation. The results are listed for blank and thethree Pb targets in Table II. The agreement between
the experimental quantities within 4.4 % is obtained.
Furthermore, we note that the numbers of incident
LCS photons determined from the experimental andthe best-fit Poisson distributions agree well within 2.2%.

4. Conclusion
We experimentally investigated the nature ofmulti-photon distributions of pulsed LCS photons
measured with the NaI(Tl) detector using blank andthe three thick lead targets and found that the multiphoton distribution is well characterized by the
Poisson distribution. We present an experimental
formula based on pile-up photon spectra measured
with the NaI(Tl) detector to determine the number ofincident pulsed LCS photons within 3.5 % accuracy ina thick target measurement.
References[1]H.Ohgaki et al., IEEE Trans. Nucl. Sci. 38 (1991)
386-392.
[2]K.Horikawa, S.Miyamoto, A.Amano, T.
Mochizuki, Nucl. Instrum. Meth. A618(2010)
209-215.
[3]T. Kii et al., Proc. 12th symposium on Accelerator
Science and Tech- nology.
[4]H. Toyokawa, T. Kii, H. Ohgaki, T. Shima, T.
Baba, Y. Nagai, IEEE Trans. Nucl. Sci. 47 (2000)
1954-1957.
[5]http://physics.nist.gov/PhysRefData/
XrayMassCoef/tab3.html[6]S.Koički, A.Koički, and V.Ajdačić, Nucl. Instrum.
Meth. 108 (1973) 297-299.

20

Resonant Photonuclear Reactions for Isotope
Transmutation
Hiroyasu Ejiri1,2 , Tatsushi Shima1 , Shuji Miyamoto3 , Ken Horikawa3 , Yasuhisa Kitagawa3
Yoshihiro Asano4, Schin Date ́5, and Yuji Ohashi5
1 RCNP, Osaka University, 2 Nuclear Science, Czech Technical University, 3 LASTI, University of Hyogo
4 RIKEN/XFEL SPring-8, 5 JASRI SPring-8
Abstract
Resonant photonuclear isotope transmutation (RPIT) is shown to be very powerful to produce
exclusively radioactive isotopes (RIs) by resonant photonuclear (γ,n) and (γ,2n) reactions via E1
giant resonances. Photons to be used are medium energy (E(γ) ≈ 12- 25 MeV) photons producedby laser photons backscattered off GeV electrons. The cross sections are as large as σ ≈ 0.2 − 0.5 b(10−24cm2) for all medium-heavy nuclei. A large fraction (∼ 3%) of photons is effectively used forthe photonuclear reactions, while the scattered GeV electrons remain in most storage rings to be
re-used. To demonstrate the RPIT feasibility, 99Mo/99mTc and 196Au RIs were produced by RPIT on
100Mo and 197Au with laser photons scattered off 1 GeV electrons at the NewSUBARU storage
ring. RPIT with medium energy photons around 1012−15/sec provides specific/desired RIs with therate of 1010−13/sec and the RI density around 0.05-50 GBq/mg for nuclear science, molecularbiology and for nuclear medicines.
1. Introduction
The present paper aims at reporting that
RPIT(resonant photonuclear isotope trans- mutation)is quite powerful for exclusive RI (radio isotope)productions (transmutations). Nuclear reactions used
for RPIT are resonant photonuclear reactions throughgiant resonances (GR) by means of laser electron
photons, i.e. medium energy photons produced bylaser photons backscattered off energetic GeVelectrons in a storage ring.
RPIT is shown to be a very efficient and realistic
way to provide various kinds of RIs to be used fornuclear physics, molecular biology, nuclear medicine
and for other basic and applied science.
So far, (n,γ) reactions and nuclear fissions havebeen extensively used for RI productions andtransmutations. Low energy thermal neutrons used for(n,γ) reactions and/or nuclear fissions are easily
obtained by using intense medium energy protons
and/or high flux nuclear reactors. RIs produced by(n,γ) reactions and those by nuclear fissions arelimited to those with large neutron capture crosssections and those with large fission branches,
respectively. Many kinds of fission product RIs,
however, are produced in addition to the specificisotope of interest, and thus chemical separation isindispensable for extracting the desired isotope.
In the present report, we discuss the possible useof photonuclear reactions for nu- clear isotope
transmutations. Actually, photonuclear reaction crosssection is in general much smaller than typical nuclear
cross sections because of the small EM coupling
constant.
The main points of the present RPIT are to use
resonant photonuclear excitations via E1 giant
resonance[1] with the large cross section and to use
energetic photon beams obtained by laser photons
backscattered off GeV electrons. Such photon beams
are called as laser electron photons. The main ideas of
RPIT are discussed in the recent report.[2, 3]

Laser electron photons for RI productions havebeen discussed, as given in recent reports andreferences therein.[2,4,5] Photonuclear reactions andphoto fissions for medical isotope productions andnuclear transmutations were evaluated by using the
FLUKA simulation code.[4] Photonuclear reactions
with photon beams of large brilliance and small band
width (∆E/E = 10−3) were discussed for production of
medical RIs with high specific activity.[5] Isotope
productions by using bremsstrahlung photons frommedium energy electron beams were discussed in the
recent report.[6] Among them, FEL(Free Electron
Laser) photons backscattered off GeV electrons in the
HIγS facility[7] is very interesting to provide medium
energy photons for RPIT.
In what follows, we describe briefly RPIT withlaser electron photons to provide efficiently various
kinds of RIs with large RI production rate and high RI
density. It is used to get RIs of interest without extra
RIs. Unique features of RPIT and the E1 giant
resonance and those of laser electron photons forphotonuclear reactions are given in section 2 andsection 3, respectively. RI production rates andefficiencies are discussed in section 4, and 99Mo/99mTc
and 196Au productions by RPIT on 100Mo and 197Au
with laser photons scattered off 1 GeV electrons at
NewSUBARU are described in section 5. Concluding
remarks and perspectives are presented in the lastsection.
2. Resonant photonuclear reactions via E1 giant
resonance
Resonant photonuclear reactions via the isovector
E1 giant resonance are used for RPIT. Merits of theresonant reactions are as given below.
1. The cross section is quite large because of theresonant excitation of many nucleons involved in the
GR. The energy integrated cross section is given by21

"

produced.

(1)
where N and Z are the proton and neutron
numbers, A = N + Z is the mass number, κ ≈ 0.2 is thecorrection coefficient for the exchange current, and α= e2/ ≈1/137 is the EM coupling constant.
Table I. Cross sections for photonuclear
reactions at E1 GR and cross sections for electron
positron pair creations and Compton scatteringsin unit of b=10−24cm2.
Isotopeσ(GR) bσ(e) bσ(GR)/σ(e)
27Al
0.07
0.95
0.071
63Cu
0.16
3.3
0.048
100Mo
0.25
6.1
0.041
124Sn
0.31
8.9
0.034
208Pb
0.52
20
0.026

Fig. 1. E1 giant resonance (GR) energy"(triangles) and photonuclear
cross sections via E1
GR (squares) as a function of the mass number A!

Using the Breit-Wigner resonance shape with theobserved width of Γ ≈ 4.5 MeV for the E1! GR, the3. Laser electron photons for photonuclear
cross section at E(γ) = E(GR) is expressed as
isotope transmutation(2)
σ(GR) ≈ 2.5 × 10−3 A b.
# & %" of- the(& # ' ' ' Medium( # " $ & energy" ) # " photons( & ' # " with"" & appropriate- " ( & '# " "+(theThe cross section amounts to about 30* cross# $ ' energy. & % )% of$ ( ,E(γ)) )≈ E(GR)& & ' % & are' )obtained$ ' . % by Comptonγ ≈' % ) $
geometrical nuclear cross section. GR resonance# " # ( $ " ! ) # " " * ) " )' "" ' " ' ( * (# " * ) " )& ' (& )backscatteringoflaser
photonsfrom GeV
electronsin()% '
sections for typical nuclei are shown in. TableI)% and
%
#
&
$
!
(
))
'
$
%
"
(
'
&
%
)%
$
(
'
%
#
"
)'
'
$
−% $ ( $'& ' # " a" storage" & ring.
- ' Laser, $ & ' photons'' are amplified≈# & (in energy ∼Fig.1. The cross section is proportional ()to& themass& % excitation.
)% $ ( ∼'# " & )" via
3 scattering( electrons))
number A because of the resonant' $ ' # $ + " ' .off
" +GeV" ' ( $ + % ffby( many' ' " orders& # )' % $ (' ofΓ. # $ ∼. % ' ' ( %magnitude,
dependingontheelectronenergyTherefore the small EM coupling of α ≈# 1/137
iswell' ! $ and)$ the)$ ' )*# "" & $ & $ & $ " (% $ )- , " ( )' % $ " $ ' " -. " )$ ) - () ' ))! " " & - $ & & # ' (#% &" '' )scattering angle. The appropriate energy " window∆
E
compensated by the large factor of A = 60∼200 in case
$ ' ' . ,' $ " % # , " (&∆ ≈' ( ≈Γ " selected( γ( " & ) (by# " .using)( ( & # ))' ' ' ' $ ( # $ " "Γ(# is' * (- $ (a collimator& ! % " " # " ))%(& ' # to" )% ' define+ 3$ & theof medium heavy nuclei.
scattering angle.
$ " '( ! ))) ' #$ " & " ' % * (() % " " ) ( ' & ' % " )% $ " () ( ( & # * )' (& )" " .()(& % ' , $ $The scattering process of laser photons is
2. GR is a macroscopic oscillation of a bulk of# (# " ) schematically& &( # " ' # shown" !
) ! Fig.2.* - " )( (&# " & !
" inprotons and that of neutrons. Accordingly the crosssection per nucleon, the resonance energy
andtheγ" # & γ " &(# " '$ " " # "
≥ γ ≥
# &
γ ≥
+
&
resonance width do not depend much on individual≈& ( # "
" (+ # " ) (& # "" "" &' & ' $ (* nuclides and insensitive to individual nuclear " structures. The resonance energy is expressed as " E(GR)≈# "(' , ) ' * - " )
+ (
−
"
−
&# ! ( & ( " )aA−1/5 = 22∼14 MeV for A = 30 ∼ 200
nuclei as - ) ' " (
+ (
γ"
"
γ " &
(# " ' + (% ) ( " & - $ # (# " 'shown in Fig.1, and the width is as broad as Γ = 4 ∼5
' $ (in* any
- "
' #
(" )
γ$ &
(# " ' &' # )'(# $ & # )' + (MeV. Thus one can preferentially excite& GR
nuclei by using medium energy photons. This
− is in # & " - ( ' $ # ' '
(#
('$
/
' &
' # (# $ ' & # ! ' (contrast to (n,γ) reactions by thermal neutrons, where' # (# nuclides$ ' # & ' # & ( * Fig. 2.	

 ' # (# Schematic$ ' & # ! # view"
* of production' # (# $ ' of+ laser( # )( $ & # ) " ! " the cross section depends much on individual
electron photons by Compton backscatteringof!
and nuclear level structures.
, (&'' ' " laser# " (&photons' ( (# /'from' # " GeV
$ & # electrons.
) (' " " )& &(# & ' +& ! " - , (&' # (# $'&"'' & - $ &#)3. Photonuclear reactions on medium heavy nuclei
Here the GeV electron is excited to a virtual stateat the GR region are mainly (γ,n) or (γ,2n) reactions,by the laser photon capture, and is split into thedepending on B(2n) ≥ E(γ) ≥ B(n) or E(γ) ≥ B(2n),scattered GeV electron and the laser electron photon,
where B(n) and B(2n) ≈ 2B(n) are the one and twoi.e. the scattered photon. The scattered photon energy
neutron binding energies, respectively. Then one' ) gets" )'is% $ expressed( - ) in)%terms+' of)* the" ()laser) photon. ) " energy( ' & % )% $& )* '$E(γ)
exclusively nuclei with (Z, N − 1) and (Z, N − 2) from
E(l)
and
the
scattering
angle
θ
with
respecttothe( (& and" ) $ (γ,2n))% ) ( )) '" )' % $ $ ) " ( ' " )' % $ & % )% $) ( )) 'target nuclei with (Z,N) by using the (γ,n)
electron beam asreactions with adequate energy photons,& respectively.
% )% $( )) '& % )% $ $ ' .
γ ( - & ' (($ ) ' # ( % ) " ( ' & % )%In case of light nuclei, (γ,p) reactions are also used to$ ' . it is$ ) ( )) ' $$ " θ , ) ' (& ) )% )" )' % $#(produce RIs with (Z − 1, N ). Accordingly,(3)
possible to get specific/desired RI isotopes fromγ
where m denotes the electronmass and γe = E(e)/γstable isotopes, or short-lived RI isotopes from longm is the Lorentz factorγof the incidentγ electron
withθ
lived RI isotopes without producing many extra RIs.
the energy E(e). Noting 4γeE(l)/m ≪ 1 in the presentThis is in contrast to fission products, in' nuclear$ % ) ( )" )' % $ # (( $γ( )% ' $ )/)% ' % )case, the photon energy can be conveniently
reactors, where many extra isotopes are necessarily$$ ) " )' % $ ,expressed
) )
$ ' .
% )$
γ
" $ ) & ' ( $ ) ( )as&% )% $$ ' .

$% $ +$$ )" .

'

≈ γ

()

(

γ

22
,

- & ' ((

# & " 3 )% $

θ
)% '

$

θ

≈

γ θ − () $( % ' )

is in contrast to bremsstrahlung photons, where thephoton yields drop down rapidly with increase of theenergy, and thus a small part of the high energy tailcan be used for photonuclear reactions.[6]5. Some laser electron photons interact with target
nuclei to excite GR, which decays by emitting 1 or 2
fast neutrons and a few γ rays, while others interact
with the electric field of the target nuclei to produce
electron positron pairs with E(e±) = 5 ∼ 8 MeV. These
neutrons, γ rays and electron-positron pairs may be
used for basic and applied science. Slowing down thefast neutrons, one may re-use them for another isotope
transmutation.[4](4)where k ≈ 4γe2 is the amplification factor, and f(θ)≈ [1 + γe2 θ2]−1 stands for the angle dependence. Sincef(θ) ≈ 1 at the forward angle of θ= 0 , i.e. thebackward angle with respect to the incident laser
photon, the laser electron photon has the maximum
energy of k E(l) with the amplification factor k ≈ 4γe2
at θ= 0.
The energy window of E(γ) − E′(γ) can be set byusing a collimator of an angle aperture of ±∆θ at theforward direction, where E(γ) and E′(γ) are the photon
energies at the scattering angles of θ = 0 and θ = ∆θ.
The laser electron photon energy and the band
width are tuned by adjusting E(l), E(e) and ∆θ so thatthe energy spectrum shows the peak at the maximum
energy of E(γ) ≈ E(GR)(∼15 MeV) and the band widtharound ∆E(γ) ≈ Γ(∼5 MeV).
The energy amplification factor is as large as k =107∼8 for the GeV electron energy of E(e) = 1 ∼3 GeV.
Then one gets medium energy photons of E(γ) ≈15
MeV to be used for photonuclear reactions by using 1∼ 0.1 eV laser photons.
The photon intensity of around 108−12/sec isrealistic by using intense lasers and intense electrons.
In future, high intensity photon sources with theintensity of the order of 1014-15/sec will be possible.

4. Photonuclear RI productions
Let’s estimate the RI production rate and the RI
density for RPIT. Photonuclear (γ,n) and (γ,2n) crosssections via the E1 GR are given as σe(n) =σe(GR)Br(n), and σe(2n) = σe(GR)Br(2n), where
Br(n) and Br(2n) are the effective branching ratios forthe n and 2n channels and σe(GR) is the effective GR
cross section for the laser electron photons in theenergy window. Practically, Br(n) and Br(2n) arenearly 1 by selecting the laser electron photon
energies as B(n) ≤ E(γ) ≤ B(2n) and B(2n) ≤ E(γ) ≤B(3n), respectively. Experimentally, we use photons
with the spectrum window of ∆ E ≈ Γ . Thus theeffective cross section is σ e(xn) ≈ 0.7 σ(xn) = 0.7
Br(xn) σ(GR).
The RI production rate N (Z, N − x) by using the(γ, xn) reaction on the A(Z, N ) target nucleus is givenasThe laser electron photons have several
advantageous points to charged particles andneutrons. They are as follows.
1. The laser photons are well collimated into asmall angular region of θ ≈ 1/γe. The angle spread isaround θ ≈ 0.15-0.5 mrad. for 3-1 GeV electrons.
Thus the nuclear transmutation is confined in thesmall cylinder within 1 mm in radius at around a few
meters from the laser electron interaction point. This
makes it possible to get isotopes with very high RI
density of the order of GBq/mg, which is crucial for
nuclear physics, molecular biology and nuclear
medicines.
2. The large fraction (∼ 3%) of the incident
photons are effectively used for the isotope
transmutation, as given in Table I. Here a very thicktarget of the order of 20∼30 gr/cm2 can be used forphoton beams since photons have no electric charge tointeract with atomic electrons. Note that charged
particles lose their energy mostly via interaction withatomic electrons without being used for nuclear
reactions.
3. The scattered GeV electrons lose the energy via
the interaction with the laser photon only by 0.3 ∼1% , depending on the scattering angle, and thus mostof them can still remain in the storage ring to be reaccelerated up to the original energy by RF power
supply.
4. The laser electron photons tuned to the GR
energy are well above the (γ,n) threshold energy. In atypical case of the maximum photon energy of E(γ) =16 MeV and the neutron binding energy of B(n) = 8
MeV, more than a half of the laser electron photons isabove the threshold energy of 8 MeV for photonuclear
reactions, and is used for photonuclear reactions. This

(5)
where N′(γ) is the number of photons per sec in theenergy window of ∆E ≈ 5 MeV, a is the attenuation
factor of the incident photons through the thick target,
and N(T) is the number of target nuclei per unit area.
We evaluate the RI production rates in two cases.
In case of FEL, the production rate can beevaluated on the basis of the HIγS data of N(γ) ≈ 2 ×
109/sec for 50 mA electrons with E(e) = 0.474 GeV
and E(l) = 1.6 eV (λ =780 nm).7) The photon intensity
increases as E(e)k with k ≈5.
Extrapolating these data, one may assume/expect
to get the total number of photons around N(γ) ≈2×1012/sec / 500 mA for E(e)=1.2 GeV and the N′(γ) ≈1012 /sec for the photons in the energy window. Usinga target with thickness of around 30 gr/cm2 and a ≈0.62, the RI production rate for a typical case of A =100, Br(n) = 0.7 and σ(GR) = 0.25 b is given as,(6)
The photons are well defined into the small
angular region of θ = 1/γe ≈ 4 × 10−4 radian, i.e.
within a radius r ≈ 0.8 mm at 2 m from the interaction
point. Then the target cylinder with 1.6 mm indiameter is 0.6 gr. Thus the RI density aftersufficiently long irradiation (multiple of the producthalf-life) is 1.5 ×10 10 /sec/0.6 gr = 0.025 GBq/mg,
which is equivalent to 0.025 GBq/ml in case of liquidwith 1 gr/cc. Using target nuclei enriched into
particular isotopes, one gets efficiently the isotope
transmutation, being almost free from other extra/23

N(γ) = 1013−15/s may provide RIs around N ≈ 1011−13/s.
The RI density is evaluated for a typical case of E(e)= 2 GeV with γe=3.9 103. Laser electron photons with
E(γ)=15 - 10 MeV and 24 - 16 MeV for (γ, n) and (γ,2n) reactions are obtained, respectively, by scatteringof 0.24 eV and 0.39 eV laser photons at θ = 0 - 0.16
mrad. Thus the collimator to be used for bothreactions are the one with aperture of ∆ θ = ± 0.16
mrad. i.e. the radius of 0.65 mm at 4 m from theinteraction point. Using a 30 gr/cm2 target, N ≈1011−13/s can be confined in a cylinder of r =0.65 mm
with the density of 0.5 - 50 G Bq/mg after longirradiation.
Let us discuss the 99Mo/99mTc isotopes, which arewidely used as SPECT isotopes. The 99Mo isotopes
are produced by 100Mo(γ,n) reactions and also
100Mo(γ,p) reactions followed by β− decays. RPIT
with N(γ) ≈ 1013−15/s and enriched 100Mo isotopes provides the RIs of 99Mo/99mTc with the production rateof 1011−13/sec and the RI density of 5 108−10 Bq/mg
after sufficiently long irradiation.

In case of CO2 laser photons injected anti-parallel
to a beam of GeV electrons in a storage ring, thenumber of the backscattered photons per sec is given
as.8)
(7)
where I is the current of the electron beam and P
stands for the power of the laser, respectively in unitsof A and W. A segment with the length l of theelectron beam is assumed to be contained inside thelaser beam of the cross section area s, respectively inunits of m and mm. A finite Rayleigh length makes sdependent on l. In case of a Gaussian laser beam, thedependence is written as(8)
where λ (10.6µm) in unit of µm and w in unit ofmm are, respectively, the wavelength and the waist
radius of the laser beam at the middle of the segmentl. To enhance N(γ) , one may increase l and reduce w.
It is however bounded by a value N0(γ) = 4.4×107 I P ,which corresponds to a sufficiently large segment
length l compared with the Rayleigh length. When arelationship l ≥ 4w2 is fulfilled, N(γ) counts more than
90 % of N0.
Low emittance electron beams in the third
generation synchrotron light sources allow us toassume w = 0.5 mm for which an adequate segment
length is l=1 meter. To obtain N(γ) = 1012/sec with I =500 mA as considered in the FEL case, the power ofthe laser is required to be P = 46 kW. To beconservative, we may say that a well establishedtechnique of the laser backward scattering utilizing a
few kW CO2 laser photons can provide a mean to
study nuclear transmutation and RI production with aproduction rate of an order of 109/s.
Radioactive isotopes to be used for PET and
SPECT tracers and photonuclear reactions are shownin Table II and Table III.

5. 99Mo/99mTc and 196Au RI productions by
RPIT
99Mo/99mTc and 196Au RIs were produced by RPIT
on 100Mo and 197Au in order to demonstrate the
RPIT feasibility. Medium energy photons with E(γ) ≈16-12 MeV were obtained by using 1.064 µm NdYAG4 lasers scattered off 0.95 GeV electrons in the
NewSUBARU electron storage ring. A collimatorwith aperture of 6 mm in diameter was used to selectthe energy window of ∆E ≈4 MeV. The photon energy
window is just adequate to excite preferentially E1
GRs in 100Mo and 197Au. The photon intensity is of
the order of 106/sec. Note that the scattered electrons
at the forward angle of θ ≈0 mrad. are not re-used in
the present NewSUBARU with E ≤ 1 GeV, although
they are re-used in most storage rings with E ≥ 2-3
GeV.
A target used consists of 6 natural Mo disks with 2
mm in thickness and 1 Au disk with 0.5 mm inthickness. Here the Au disk is inserted just between
the 3 and 3 Mo disks. Note the natural Mo includes
9.6 %100Mo, while the natural Au is 100 %197Au.
They are irradiated by the medium energy photons for
8.89 hrs (hours), and the γ rays from RIs are measured
by means of GMX Ge detector after 0.82 hrs from thestop of the irradiation.
The γ ray energy spectrum measured for 1 hr from0.82 hrs after the irradiation is shown in Fig. 3. The
100Mo stable isotopes were well transmuted to the
99Mo RIs, as shown by the very strong 140.5 keV γline from the 142.5 keV isomer in 99Tc (T1/2 =6.0hrs), which were populated from 99Mo (T1/2 =66 hrs)
decays. Strong 739.5 keV, 778 keV and 181 keV γlines from 99Mo (T1/2 =66 hr) decays are also
observed. Note that the strong 140.5 keV γ ray is justthe one used widely as the medicine for SPECT.
Interesting is to see the 569 keV and 658 keV lines
from 96Nb (T1/2 =23.4 hrs) and 97Nb (T1/2= 72.1 m),
which are produced by the (γ,p) reactions on 97Mo
and 98Mo, respectively.
The strong 355.5 keV, 333 keV, and 688.5 keV

Table II. Radioactive isotopes to be used for PET
tracers and photonuclear reactions.
Isotope Halﬂife Q(EC) keV Reaction Abund
11C
12C(γ,n)20.4 m
1982
98.9
13N
14
10.0 m2220
N(γ,n) 99.6
15O
16O(γ,n)2.04 m
2754
99.8
18F
19F(γ,n)109.8 m
1656
100
62Zn
64Zn(γ,2n) 48.6
9.2 h
1627
68Ga
69Ga(γ,n)67.6 m2921
60.1
Table III. Radioactive isotopes to be used for
SPECT tracers and photonuclear reactions.
Isotope Halﬂife d Q(EC) keV Reaction Abund
67Ga
3.26
93, 185 69Ga(γ,2n) 60.1
99Mo/99mTc 2.75, 0.25
100Mo(γ,n)
140
9.6
111In
2.8
245, 171 113In(γ,2n) 4.3
126I
13389, 666 127I(γ,n)
100195mPt
196Pt(γ,n)
4.02
259
25.4
201Tl
203Tl(γ,2n) 29.5
3.04
167

Intense sources of medium energy photons with

24

$ 2-

*

(333 + 355.5) γ lines are from EC and β+ decaysof, ( $196Au and the 426 keV line is from β− decays of
196Au, which are produced by RPIT on 197Au. The 67
keV and 75 keV lines are K X-rays from Pt and Pb,
respectively.
Relative yields of 99Mo and 196Au isotopes areevaluated by using the measured yields of the 181
keV and 355.5 keV lines from their decays,
respectively. They are plotted as a function of the time
T from the start of the irradiation as shown in Fig. 4.
They are consistent with the known half lives of 99Mo
196Au.
and
+)




 

       

nuclear data[9–11] and the peak efficiencies estimatedby using the Monte Carlo simulations.

% #

''



(



     Fig. 4. Relative yields of the 181 keV γ rays from
99Mo (squares) and the 356 keV γ rays from! ) + 196Au(triangles), ! ( $ ), ( '$ "* ' ( T # (K)as γa ' functionof $ the(& timeby' )photons.
* )' # ! ( (sec)* # from
) $ # $ the) start) " of the( irradiation' $ " ) ()$ )'') $ # ()$ % % The) irradiation' ( stopped( at #T =) 8.89
γ ' hrs, $ (32* # )K# sec)() ' )
hrs* (35$ started at T=' ( 9.71#$ ! ! # ( ' and the, * γ' + ray( $ counting)
K sec). Solid lines are decay curves of the 99Mo
(T1/2 = 66 hrs) and 196Au (T1/2=6.18 d)!

& -%γ ' , ( '$
)$ #

, %

$ )$ # ()'(

Then the effective cross sections are expressedsimply* ' , as!
' " + ' ,' ( + *. $- ,* ' % ,! ' + * .

1" $ + '#γ * 1+ * ' % , !
'1+ & , ! , ' * , !
- * * ' % ,!
Fig. 3. Gamma ray energy spectrum from# RPIT&(10), 2 natural! ) ! , # 2 - +! Mo. , /(and" , * (Au targets.
* ) ) . /,The' * γ )rays/ at. , 140.5# ! .$ ! γ , 2- .
on
1" $ ' , !
#γ * 1+ * ' % , !
1+ * + ( , " . $ 1* , ! γ * 1 1" $$ ! 778γ , 2- keV.
& ! from)& !
,! " ,* (
& !
& !
& !
)
& ! 739.5, ! " , * (keV, * andkeV,
181keV,are,(11)* are' & !* * ,' where* ,!
* & ! " and& * σ e(C), " ' + # are& ' / the& * number' % , ! &of- isotopes$ *,& ,! (), ! 99- +!Mo.
. % 0! ' The
2 $ ! γγ ,rays
2- . at 569
& !
& !
)/
keV& ! and 658
keV
N(C)/ from$ !
& !
) and 97Nb,& !
' % ) ! respectively.
- ,!
, 2- 1 $ % The' ! . $ ! γ rays
& ! at' % ) ! % - . $ ! involved! ' ! .,* ),! " ,* (
96Nb
in
the
present
RPIT,
and
the
effectivecross
ffi " & " + + , " % ,1 - + " & ,!
' & ,* $ ' + " % - $ ," ' & ++* - % . , * ) ) ) % $ % ' . 333% * ) keV, 355.5 keV, 426 keV, and 688.5 keV(333section with C standing for the product RIs of 99Mo
! & , ! andff ,196" . Au,* ' and+ + + for, " ' the& + stable*0(target* + + isotopes+ " % ( $ 1 of
+ 100Mo+ 355.5) are from 196Au. The 66.5 keV and 74.5
keV lines are X rays, while the 511 keV line isand 197Au.
σσ
the electron positron annihilation.
Using the observed excitation function for% ! $ ))
( * # )$ # $ ) )"' $ " ) () ' ) $ )'') $ # ( ( $ , # # 197
Au[12] and the observed energy dis- tribution of- '$ # ( ()Effective# ) , ) ) cross# $ , # sections! ! + ( $ for$ the
#
*
RPIT
(γ,n)
N(γ,E(γ)),σ we get σe(σ196Au) = 0.365 ±0.012 b, Thenff ) + productions' $ (( ( ) $ # ( $ of' ) 99Mo andγ # % 196
' $ Au* ) $ # isotopes($$ # were * ($the)$ % effective(
cross section for 100Mo(γ,n)99Mo is
/
!
*
&
σ
*
,
! Eq.(11)
& -%
* and
' " + the' , ' σe(( + 196" & Au). ' $ . = 0.365" & ,! b ( * + & ,&evaluatedfromthenumbersoftheseisotopes
obtained
by
using
, '
+ !* )'$ " ) # * "' ( $ ) ( ($ )$ % ( % ' $ *- )% $ )$ # ' '99
produced
by
the
RPIT
photonirradiation
by
using
as
σe(
Mo)
=
0.109
±
0.020
b,
including
a
small
,!
ff , " . * ' + + + , " ' & / " , !
+ , & "&
' * ,! ( * ' - , + '' &- &)$ # - * (#&Eq.(5).
contribution from (γ,p) channel. The effective cross)) # * )The
$ # $ attenuation)## ) % of$ )$the# ( )incident'$ *) photons$ # ' through+ , # * - , " + ' for* * ,)! ' + )(, ($ sections, ' ( the+ ' 98Mo(γ,' p)& 97Nb and- 97Mo(γ, p)96Nb≈$ ' the) % Mo' ( # and) ) ' Au) targets# ( " ! is given by a ≈ 0.78 for+ " thewereevaluatedfromtheobserved& ,! ' + * .
0 " , , " ' & - & , " ' & ' * yields- of& the, ! 658' + *.
& * 1 "
keV and 569 keV γ rays from 97Nb and 96Nb,
ff present) + # * " target' $ % ensemble.
$ )$ # ( ! γ , '' +(, * " - were," ' & 'γ respectively.
γ /, σ are -about 3 % of the effective! & ,!
ff , " . * '!
The effective numberof photons, N′(γ),
They
!
γ
γ
γ
γ
derived as
(γ,n)
cross
sections.
Then,
assumingthe3%+ ," ' & ' *' γ&' "+ ' , "&1 -+ "&)& ,! σcontribution
to the 99Mo production from the (γ,p)
, '
γ
γ ()
# ' - ()' * ) $ # $ )## ) % $ )$ # ( ) (9)
'$ *
)
" "
channel, one gets the effective cross section of$ ! ! " )$ ' ( where' ! N(γ,E(γ)))+# ' - is ()'the * energy)$ # $γγ , ( of" the(* '- * (99
distribution
σe( # Mo) = 0.106 ± 0.020 b. This is in consistent withphotons through the 6 mm dia. collimators.
' - () incident!
the value 0.105 b derived from the measured (γ, n)
The relative energy distribution of N(γ,E(γ)) was
cross section on 99Mo,[13] and is consistent also withmeasured by using a NaI crystal.
the cross section evaluated by using the number of the
The number of the 99Mo isotopes are evaluatedlaser electron photons and the number of thefrom the observed yields of 181 keV and 739.5 keV γmeasured 99Mo isotopes.
rays from the 99Mo decays and that for the 196Au are
We note here that the effective (γ,n) cross sections
from the yield of the 355.5 keV γ rays from the 196Au
for 197Au and 100Mo are approximately 69% and 62%
decays, respectively. Here the γ ray yields wereof the GR peak cross sections of σ(GR), respectively.
corrected for the branching ratios known from the( (25

6. Concluding remarks and perspectives onphotonuclear reactions
The present report shows that RPIT with laser
electron photons provides exclusively various kindsof specific/desired isotopes with the large production
rate and the high density for basic and appliedscience. RPIT is of potential interest also for nuclear
transmutation of long-lived nuclei. Accordingly,
RPIT using intense laser photons and GeV electrons
in a storage ring is quite complementary to othermethods using high flux reactors and intense charged
particle accelerators.
RPIT with large efficiency is quite attractive from
ecological view points. Since the GeV electrons
stored in most storage rings lose little their energy via
interactions with laser photons, they remain in thering. The laser electron photons are efficiently used
for production of desired RIs. Then the overall
efficiency of the RI production is many orders ofmagnitude larger than that of the charged particle
accelerators and nuclear reactors. Fast neutrons haverecently pointed out to be used for nuclear
transmutation.14) This uses a small fraction of thecharged particles to produce the fast neutrons, and iscomplementary to RPIT. Intense electron accelerators
provide bremsstrahlung photons for photonuclear
isotope transmutation,6) but most of photons are
below the threshold energy of the photonuclear
reaction and the electrons after the bremsstrahlung are
not re-used.
There are several programs of intense photon
sources under progress.[4,5,15] MEGa- ray is the
project at LLNL for high intensity photons with 1012
photons/sec in the MeV region and ELI-NP is the one
at Romania for higher energy photons with 1013
photons/sec in the GR energy region of E(γ) ≥ 19.5
MeV. They plan to achieve the intensity of around1015/sec. In Tokai Japan, the ERL(Energy Recovery
Linac) project is under progress to provide intense
photons for resonance fluorescence.[16]It is noted here that the laser photon backscattering
off GeV electrons in an electron storage ring is wellestablished and it requires fewer developments
compared with linac based facilities like ones plannedin Romania and Tokai.
If the natural abundance of the target nuclide is notlarge, enrichment in the specific isotope is effective toincrease the efficiency by the enrichment factor and to
reduce other RI productions. Ton-scale enrichment
into 100Mo for 99Mo/99mTc and other isotopes are
realistic by means of centrifugal isotope separators.
Such isotopes are also used for basic science such as
neutrino studies in double beta decays.[17] A large
scale isotope separation plant with the separation rateof the order of 100 kg/year is interesting for basic andapplied science.
RPIT can be used to detect small impurities of
specific stable and radioactive isotopes. They are
excited by photonuclear reactions via E1-GR, and are
detected by measuring prompt and delayed gamma
rays characteristic of the isotopes of the order of ppb/
ppt levels. Thus it can be applied for nondestructive
impurity and radionuclide assay.

It is of great interest from scientific and ecologicalview points to build high intensity electron storagerings and FEL photon sources to provide medium
energy photons with intensity of the order of 1013−15/
sec. Such intense photons can be widely used for
producing byproduct fast neutrons, γ rays and electron
positron pairs as well as for the photonuclear RI
productions for basic and applied science.
References[1]A. Bohr and B. Mottelson: Nuclear structure I,II
(Benjamin INC, New York 1969, 1975).
[2]H. Ejiri: Proc. Nuclear Materials Workshop,
Saskatchewan Canada, April 2010. http://physics.usask.ca/ chang/department/index.html[3]H. Ejiri and S. Dat ́ e: arXiv:1102.4451v1 [nuclexp][4]B. Szpunar and C. Rangacharyulu: Proc. Nuclear
Materials Workshop, Saskatchewan Canada, April
2010. http://physics.usask.ca/ chang/department/
index.html; Proc. YS4-APSE2010, The 4th Yamada
Symposium on Advanced Photons and Science
Evolution, ed. H. Ejiri, Osaka, June 2010, http://w w w. y a m a d a z a i d a n . j p / y s / a p s e 2 0 1 0 /proceedings.html[5]D. Habs and U. Koester: arXiv:1008.5336v1[physics. med-ph].
[6]G. G. Bunatian a, V. G. Nikolenko and A. B.
Popov: arXiv 1012.5002v1 [nucl-exp, Dec 2010].
[7]H.R. Weller, M.W. Ahmed, H. Gao, W. Tornow,
Y.K. Wu, M. Gai, and R. Miskimen: Prog. Part.
Nucl. Phys. 62 (2009) 257. http://
www.yunl.duke.du/higs/[8]S. Dat ́ e: Proc. Nuclear Materials Workshop,
Saskatchewan Canada, April 2010, http://physics.usask.ca/ chang/department/index.html[9]B.B. Firestone, V.S. Shirley, S.Y.F. Chu, C.M.
Baglin and J. Zipkin: Table of Iso- topes(WileyInterscience 1996).
[10]L. Chunmei, W. Gongqing, and T. Zhenlan: Nucl.
Data Sheets 83 (1998) 145.
[11]J. K. Tuli, G. Reed, and B. Singh: Nucl. Data
Sheets 93 (2001) 1.
[12]A. Veyssiere, H. Beil, R. Bergere, P. Carlos, andA. Lepretre: Nucl. Phys. A 159 (1970) 561.
[13]H. Beil, R. Bergere, P. Carlos, A. Lepretre, A. De
Miniac, and A. Veyssiere: Nucl. Phys. A227 (1974)
427.
[14]Y. Nagai and Y. Hatsukawa: J. Phys. Soc. Jpn. 78(2009) 033201.
[15]C. Barty, Development of MEGa-Ray technology
at LLNL, http://www.eli-np.ro/ . http://www.elinp.ro/executive[16]R. Hajima, N. Kikuzawa, N. Nishimori, T.
Hayakawa, T. Shizuma, K. Kawase, M. Kando, E.
Minehara, H. Toyokawa, H. Ohgaki: Nucl. Instr.
Meth. A608 (2009) S57.
[17]H. Ejiri: J. Phys. Soc. Jap. 74 (2005) 2101.

26

Soft X-ray Source by Laser Produced Xe Plasma
S. Amano, K.Masuda, S.Miyamoto, T.Mochizuki
LASTI/UH
Abstract
The laser plasma soft X-ray source in the wavelength rage of 5-17 nm was developed, which
consisted of the rotating drum system supplying cryogenic Xe target and the high repetition ratepulse Nd:YAG slab laser. It demonstrated the maximum conversion efficiency of 30% and the soft
X-ray generation with the high repetition rate pulse of 320 pps and the high average power of 20
W. The soft X-ray cylindrical mirror was also developed and successfully focused the soft X-ray
with an energy intensity of 1.3 mJ/cm2. The plasma debris mitigation with Ar gas will allow a long
lifetime of the mirror and a focusing power intensity of 400 mW/cm2 with 320 pps. The highpower soft X-ray is useful for various applications.

35

CE [%]

30

6

8

25
20
15
10
5
0
-30

-20

-10

0

10

Lens position [mm]20

Fig.2 Conversion efficiency (CE) as a function oflens position.

In order to increase an intensity of this soft Xray, we designed a focusing mirror system. The
mirror has a shape of a cylinder with three piecesof cylindrical Ru coated mirror. The piece with anangle of 101 degrees had a curvature radius of 26
mm. The mirror system was placed at a distanceof 93mm from a plasma point, that was designed
to be maximized a focused X-ray energy bycompromising accepted solid angle for the lightsource and Ru mirror reflectivity. The X-ray
energy intensities at a focal plane were measured
by a X-ray diode having a sensitivity in 13.5 nmwith 2 % bandwidth. Taking account of reflected
spectra, the X-ray intensity in the rage of 5-17 nm
was estimated as shown in Fig.3. As the measured
results, a maximum focused intensity was 1.3
mJ/cm2. With the mirror, the X-ray intensity at a
focal point was improved to be 27-times.
Lithium fluoride plate was used to observe thefocused X-ray pattern. X-ray generates colorcenter in Lithium fluoride. Because a band-gap
of lithium fluoride is bigger than 14eV, its color-

Intensity [a.u.]

Laser-plasma-X-ray is generated from hightemperature and high-density plasma produced byhigh-intensity laser. This X-ray source is usefulfor a lot of applications as a compact light sourcewith high intensity. In order to use this lightsource for industrial uses, high average power isrequired. The rotating drum Xe cryogenic target,
which could supply continuously solid Xe target
for laser-produced plasma soft X-ray, wasdeveloped to satisfy this demand.
As shown in Fig.1, spectrum from the Xe has avery broad bandwidth (5-17 nm), so it was
expected to be a high efficient soft X-ray source.
When a Nd:YAG laser irradiated the target with alaser energy of 800mJ and 300mJ, a maximum
conversion efficiency in bandwidth of 5-17 nm
was found to be 30 % (Fig.2) and 21 %,respectively. The irradiation laser with a highaverage power (100 W) and a high repetition ratepulse (320 pps) was also developed originally. It
is a PCM-MOPA (Phase Conjugated Mirror –Master Oscillator and Power Amplifier) Nd:YAG
slab system. High average output soft X-ray of 20
W at the wavelength range of 5-17 nm wasrealized by using both the target and the laser.

10 12 14 16

Wavelength [nm]Fig.1 Spectrum of soft X-ray radiation from therotating cryogenic Xe target.

27

where PAr is the Ar pressure, k is the Boltzmann
constant, T is the gas temperature,  is the crosssection and l is the debris flight length. From thisfitting, we obtain  = 2.0 × 10–20 m2. The Ar
buffer gas successfully mitigated the effect ofplasma debris with little X-ray attenuation.
Increasing the Ar pressure, mirror erosion
decreases but X-ray attenuation increases.
Compromising the erosion and X-ray attenuation,
an optimized pressure is achieved. We should
localize the higher density Ar gas to only thedebris path so that EUV attenuation is as small as
possible. We can design the optimized pressure
condition using the  value obtained and we
consider the use of an Ar gas jet. Through thismitigation, we expect that erosion will be reducedby more than two orders of magnitude and thelifetime of the mirror will be extended.
This debris mitigation allows our LPP source tocontinuously operate with the longer mirror
liftime and achieve a focusing power intensity of
400 mW/cm2 with 320 pps. This high power soft
X-ray is useful for various applications.

Energy Intensity [mJ/cm2 @1mm]

center can be produced only for X-ray, not visible
light and UV light. The produced color-centers
emit yellow light by pumping blue light, and we
can know a pattern of X-ray by observing theyellow pattern. The measured pattern was in good
agreement with a calculated one.

with the mirror
without the mirror

1.4
1.2
1.0

FWHM
1.8mm

1.26mJ/cm 2

0.8

X 27

0.6
0.4

0.047mJ/cm 20.2
0-15 -10

-5

0

5

10

15

Distance from beam center [mm]1.2

Fig.3 Energy intensity at the focal plane w/o themirror.

All debris sputter
Ion sputter

N/N0

1.0

Although Xe is a deposition-free target, mirror
sputtering by debris needs to be mitigated.
However, the major plasma debris component isions, and we believe their mitigation to be simple
compared with the case of a metal target such as
Sn, using magnetic/electric fields and/or gas. We
are now studying debris mitigation by Ar buffer
gas. Ar gas was chosen because of its higher
stopping power for Xe ions and lower absorptionof X-ray, and its easy handling and low cost.
After the vacuum chamber was filled with Ar gas,
total erosion rates were measured using a goldcoated quartz crystal microbalance (QCM) sensor
placed 77 mm from the plasma at a 45-degree
angle, and simultaneously, X-ray losses weremonitored by an X-ray diode placed 200 mm
from the plasma at a 22.5-degree angle. Figure 4
shows the erosion rates as a function of Ar gas
pressure. The rates were normalized by theerosion N0 at a pressure of 0 Pa. When the Ar
pressure was 8 Pa, we found the erosion rate was
1/18 of that without the gas, but the absorption
loss for EUV light was only 8%. The erosion
rates (N/N0) in Fig. 4 can be fitted to an
exponential curve:

0.8
0.6
0.4

1
18

0.2
0.0

0

2

4

6

8

10

Ar pressure [Pa]Fig.4 Normalized sputtering rate vs. Ar pressure.

References[1] S.Amano et al., IEEJ Trans. EIS, 130,
pp.1768(2010).

 P
Ar l N P
 N  exp

 kT

Ar
0

,

 

28

Characterization of a laser-plasma extreme-ultraviolet source
using a rotating cryogenic Xe target
S.Amano, K.Masuda, A.Shimoura, S.Miyamoto, T.Mochizuki
LASTI/UH
Abstract
A laser-plasma source for extreme-ultraviolet (EUV) light that uses a rotating cryogenic solid-state
Xe target has been characterized. We focused on parameters at the wavelength of 13.5 nm with 2%
bandwidth required for an EUV lithography source and investigated improvements of theconversion efficiency (CE). With the drum rotating, there was an increase in CE and less fast ionscompared with the case for the drum at rest. It is considered that the Xe gas on the target surface
can produce optimal-scale plasma, satellite emission lines in Xe plasma effectively increase the
EUV intensity, and the ion number is decreased by the gas curtain effect. The dependence of CE
on the laser wavelength, laser energy and intensity also studied. As a result, the maximum CE was
0.9% at 13.5 nm with 2% bandwidth under the optimal condition. By continuous irradiation of a
Nd:YAG slab laser at a repetition rate of 320 Hz and an average power of 110 W, the target
continuously generated EUV light with an average power of 1 W at 13.5 nm with 2% bandwidth.
Introduction
Recently, there has been strong expectation ofusing an laser-produced-plasma (LPP) x-ray
source as a light source for x-ray projection
lithography, which is referred to as extreme
ultraviolet (EUV) lithography and is expected to
be used for the mass production of nextgeneration semiconductor chips. For this purpose,
great efforts have been made to develop such an
LPP-EUV source.
Light at 13.5 nm with 2% bandwidth isrequired for the EUV light source, which islimited by the reflectivity of Mo/Si mirrors in a
projection lithography system. Xe and Sn as
plasma targets have been studied intensively
because they have strong emission around 13.5
nm. The emission peak from a Sn target is at 13.5
nm, therefore Sn intrinsically has a high EUV
conversion efficiency (CE) at 13.5 nm with 2%
bandwidth. However, such a metal target would
deposit and remain on EUV mirrors near theplasma, degrading their reflectivity in a shortperiod. On the other hand, Xe is an inert gas anddoes not deposit on mirrors, and it has beenstudied as a deposition-free target. Unfortunately,
its emission peak is at 10.8 nm. Improvement of
the CE is a critical issue for the Xe target.
We chose Xe as a deposition-free target anddeveloped a rotating cryogenic drum target
system, which could continuously supply a solid
Xe target. We also developed a drive laser, which
was a phase conjugated–maser oscillator power
amplifier Nd:YAG slab system with a pulse
repetition rate of 320 Hz. Using the above, weconstructed an LPP-EUV light source system andwere able to continuously generate EUV light. In
this paper, we report the performance of the EUV
light source, especially the improvements of the
CE at 13.5 nm with 2% bandwidth.

Experiments
A cylindrical drum in a vacuum chamber isfilled with liquid nitrogen, and thereby the copper
surface is cooled to the temperature of liquid
nitrogen. Xe gas blown on the surface iscondensed to form a solid Xe layer. The drum
coated by the solid Xe layer rotates around thevertical z-axis and moves up and down along thez-axis during rotation, moving spirally so that a
fresh target surface is supplied continuously forevery laser shot. Two wipers are mounted on thecontainer wall to adjust the thickness of the solid
Xe layer to 500 m and assist in recovering thelaser craters on the target. The thickness of 500
m was found to be sufficient for a laser shot of 1
J not to damage the drum surface.
Figure 1 shows the experimental setup to
obtain data of EUV emission from the cryogenic
Xe target on the rotating drum. Here, aconventional Q-switched Nd:YAG rod laser wasused in single-shot operations, which coulddeliver pulses at wavelengths of 1 (1064 nm),2 (532 nm) and 3 (355 nm). The laser pulse
width was about 10 ns. The pulses were expanded
by a beam-expander and focused on the target bya lens with a focal length of 500 mm so thatplasma was produced and emitted EUV radiation.
By changing the position of the focusing lens tochange the laser spot, the laser intensity on thetarget was adjusted to find the optimum intensity.
We note the lens position (LP) is zero at best
focus, negative for in-focus (the laser spot in thetarget before focus) and positive for out-of-focus(beyond focus). An EUV energy detector
calibrated
absolutely(FC)(SCIENTECEngineering, Flying Circus) and a relative energy
monitor (EM) comprising an x-ray diode with
Mo/Si filter (IRD, AXUV-20) and a Mo/Si mirror
were used. Spatial distributions of the EUV

29

emission were measured by scanning the EM on arotating stage. A charge collector (CC) detected
the plasma ions.

considered to be Xe gas localized on the target
surface by the wiper. We supposed that the gas
produces optically thick plasma, satellite lines in
Xe plasma would contribute effectively toincreasing the EUV intensity, and the ion number
is decreased by the gas curtain effect.
The laser wavelength dependency of the CE
was investigated and it was found that the
maximum CE was obtained for the 1 laser andthe rotating drum target. It was also found thatlaser energy of more than 0.3 J was sufficient toachieve the maximum CE with an optimal laser
intensity of ~1010 W/cm2. In conclusion, themaximum CE was found to be 0.9% at 13.5nm
with 2% bandwidth for the optimal condition, andthis value is higher than that for a Xe gas or liquidstate target but lower than that for a Sn target.
When a slab laser having a repetition pulse of
320 Hz and an average power of 110 W irradiatedthe rotating target, continuous EUV generation
was achieved with average power of 1 W at 13.5
nm with 2% bandwidth. The moving average of
the EUV energy stability over 50 pulses wasestimated to be 3% (1), but it could be improved
using a laser-diode pumping laser. Using ahigher-power drive laser with a repletion rate of
10 kHz and laser energy of 1 J, EUV power of
100 W at 13.5 nm with 2% bandwidth will beobtained. No degradation of the Mo/Si mirror
reflectivity up to 106 shots was recognized. The
main plasma debris from the Xe solid rotatingtarget was plasma ions and it is thought that they
can be mitigated easily compared with debris
from a Sn target.

Faraday
IsolatorP

EUV
CameraFC
EM

Nd:YAG
rod LaserCCTG
Xe cryogenic Drum

Soft x-ray
CCD

EM
MoSi Mirror

X-ray Diode

Figure 2. Experimental setup to obtain data of
EUV emission from the cryogenic Xe target on
the rotating drum.

CE (%/sr/2%BW) at 45°

Results
We investigated the CE from the laser to EUV
using the 1 laser pulse. Figure 2 shows the CE
per solid angle as a function of LP (laser
intensity), which was measured by the FC locatedat 45 degree from the laser incident axis. The
laser pulse energy was 0.8 J. We see that the CE
was enhanced under the rotating drum condition
compared with the rest condition. Here, the rest
condition is as follows. Xe gas flow is stopped (0mL/min) after the target layer has formed, and thedrum rests (0 rpm) during a laser shot andstepwise rotates after every shot so that a fresh
target is supplied to the point irradiated by thelaser. The rotation condition is as follows. Laser
pulses irradiate quasi-continuously the target on
the rotating drum, supplying Xe gas (40 mL/min)and forming the target layer. Here, the rotating
speed was 130 rpm. In Fig. 2, we see that the
maximum CE per solid angle was for an
optimized laser intensity of 1 × 1010 W/cm2 (LP =–10 mm) during rotation. Measurement of the
EUV angular distribution by a scanning EM
shows that the distribution can be expressed by afitting curve of (cos)0.38. Taking into account this
distribution, we obtained the maximum spatiallyintegrated CE of 0.9% at 13.5 nm with 2%
bandwidth.
For the drum rotating operation, we found thegood characteristics of not only increased CE but
also less fast ions compared with the case withthe drum at rest. The cause of the phenomena was

0.2

(a)

Rotating target

0.15

0.1

Rest target

0.05

0
-30

-20

-10

0

10

20

Lens position (mm)Figure 2. CE as a function of LP in the rotation(130 rpm) and at-rest (0 rpm) conditions. Insets
show the laser beam focusing on the target.
References[1] S.Amano et al., Appl.Phys.B, 101,213 (2010).

30

Soft X-Ray from Laser-Produced Xe and Sn Plasmas
in a Wide Wavelength Range
Tomoaki Inoue, Takayasu Mochizuki, Shuji Miyamoto, Sho Amano,
Takeo Watanabe, and Kazuhiro Kanda
Abstract
Soft x-ray conversion efficiencies in a 5–17-nm wavelength range in xenon and tin
plasmas produced by a 1.06-μm Q-switched neodymium-doped yttrium aluminum
garnet laser were found to be extremely high. They were measured to be 25% and 20%
for the xenon and tin plasmas, respectively, at a laser intensity of about 2 × 1010 W/cm2.
These results indicate that a stand-alone soft x-ray source using a laser-produced xenon
or tin plasma is useful for various applications that require intense, soft x-ray photons ina wide wavelength range.
Introduction
Soft
x-raysfromhigh-temperature,high-density plasmas produced by focusing ahigh-intensity laser pulse on target materials are
expected to be useful for various applications. These
include extreme ultraviolet lithography (EUVL) that
requires an intense output power at 13.5 nm within abandwidth of 2%,1 and material processes that
require a bulk number of photons with a much wider
bandwidth. We have studied soft x-ray generation inlaser-produced plasmas using tin, xenon, and lithium
targets.2,3,4 N. Matsuo et al found that laser-plasma
soft x-ray irradiation before excimer laser annealing(ELA) reduced the critical energy density for thestart of crystallization of a-Si film.5 The effect theyobserved will enable us to realize a low-temperatureprocess for ELA crystallization.6
A cryogenic xenon target efficiently emits alarge number of soft x-ray photons with an intense
spectral peak at 10.8 nm,2 whereas a tin target emits
13.5-nm photons selectively and efficiently.3 The
conversion efficiency (CE) at 13.5 nm within abandwidth of 2% has been intensively studied.7
However, the CEs in a cryogenic xenon target and atin target in a wide soft-x-ray wavelength range havenot been reported yet, to the best of our knowledge.
In this paper, we report on soft-x-ray CEs
spectrally integrated in a 5–17-nm wavelength range
in cryogenic xenon target and planar tin target
plasmas produced by a 1.06-μm Q-switchedneodymium-doped yttrium aluminum garnet(Nd:YAG) laser.

spot would not overlap the previous shot’s spot evenat a laser-pulse repetition rate of 320 pps.9,10 A
Q-switched 1.06-μm Nd:YAG rod laser was focusedthrough a f/500 lens down to a minimum spot
diameter of 50 μm on the drum target surface. The
laser pulse duration and pulse energy were 8 ns at
FWHM and about 300 mJ/pulse, respectively. The
laser intensity was adjusted by changing the lensposition (LP). The vacuum pressure in the irradiationchamber was maintained at less than 0.2 Pa by using
a turbo-molecular pump when the xenon target gas
was loaded into the drum chamber as the drum
rotated. A Flying Circus 3 (FC3) was mounted at −45
degree to measure the plasma emission energy.11 The
FC3 was composed of a Mo/Si mirror, a Zr filter, andan x-ray photodiode, and it was absolutely calibrated
in energy sensitivity for a bandwidth of 13.5 nm ±1%. An x-ray calorimeter was mounted at 22.5
degree. The plasma emission spectrum between 5
and 17 nm was observed using a transmission grating
spectrometer (TGSM) mounted at 45 degree. The
TGSM was consisted of a transmission grating and acharge-coupled device (CCD) camera. The
characteristics of the transmission grating werestudied by K. Eidmann et al,12 and the wavelength
sensitivity of a pixel in the CCD camera was studied
by Yuelin Li et al.13
By using the absolute energy at 13.5 nm ± 1%
in the FC3 as a reference and combining it with therelative x-ray spectral intensity, we obtained the total,
absolute x-ray emission energy integrated for the
5–17-nm range. In separate experiments, we foundthat angular distribution of the x-ray emission was(cos)0.38 by monitoring the x-ray calorimeter signals
at different angles.14 Therefore, here we assumed theabove angular distribution in 2π space for the x-ray
emission. CE was then derived by dividing the x-ray
energy integrated by the incident laser energy.
The experiment was performed with a single
laser shot in two modes, in which the xenon target
was rotating or stationary, respectively. For
comparison, a similar experiment was performed
using a planar tin target. The x-ray energy from thetin plasma at 5–17 nm was evaluated using an x-ray

Experiments and Results
In the present experiment, a cryogenic xenon
drum target was used in an irradiation chamber. The
target is described in detail elsewhere.8 Here we
describe it briefly. A xenon target layer was formedon the surface of a rotating copper drum that wascooled by liquid nitrogen inside the drum. The
thickness of the target layer was adjusted to be about
500 μm during rotation by two wipers that were
installed inside the cover on the drum. The rotation
speed was set to 130 rpm so that the lasers focused

31

calorimeter calibrated by FC3, as previously
described for the xenon target.
X-ray spectra obtained for the 5–17-nm
wavelength range from the rotating xenon target, thestationary xenon target, and the planar tin target are
shown in Fig. 1. The LP was fixed at −5 mm, where
the measured CE was about the maximum for eachtarget. The x-ray spectrum of the tin plasma had an
intensity peak at 13.5 nm attributable to the 4d–5ptransition in tin ions. The spectrum profile in the
xenon plasma varied significantly, and the x-ray
conversion efficiency increased as the xenon target
rotated. The spectrum for the rotating xenon target
had a broader bandwidth than that for the tin target.
The maximum soft x-ray CEs for the xenon
and tin plasmas were measured to be about 25% and20%, respectively, between 5 and 17 nm at about LP= −5 mm, where the laser spot size on the target
surface was about 500 m (FWHM), and thus, thelaser intensity was evaluated to be about 2 × 1010
W/cm2.
The intensity at 12–16 nm in the cryogenic
xenon target was enhanced by a factor of about 3 byrotating the target. This suggests that the two wipers
increase the surface temperature of the target layer,
thereby preforming a xenon gas layer on the surfaceof the cryogenic target while the drum rotates. The
result is a plasma density profile having a relatively
long scale length in the target plasma. Such a density
profile would lead to an increase in the optical
thickness, which makes the emission spectrum more
blackbody-like.
From the above results, we concluded that the
CE in the cryogenic xenon target is as high as that in
the tin target. However, although the tin target would
be prepared as micro-droplets by using a jet nozzle
system, it still produces plasma debris that tend todeposit on the x-ray optics unless a strong magnetic
field is provided for ion shielding.15 A buffer gas
method would be a simple and effective method ofshielding the optics against bombardment by fastions for any target.16 Nevertheless, it would be
difficult to stop the tin ions from being deposited on
the optics after they have been decelerated or
neutralized by collisions with buffer gas molecules
and have started to drift slowly in the chamber.
Therefore, using the cryogenic xenon target seems
more realistic than using the tin target for soft x-ray
generation for long-term operation if we need not
require such a narrow band width as ±1% for EUVL.
In conclusion, we obtained CEs as high as 25%
and 20% in laser-produced xenon and tin plasmas,
respectively, for the 5–17-nm wavelength range.
These results indicate that a stand-alone soft x-ray
source using a laser-produced xenon or tin plasma isuseful for various applications that require intense,
soft x-ray photons in a wide wavelength range. A
practical, intense, soft x-ray source may be moreeasily realized with a cryogenic xenon target thanwith a tin target. The soft x-rays from thelaser-produced plasma are intrinsically pulsed andyield significant CEs such as those we obtained. Ahigh soft-x-ray irradiation intensity of more than 104
W/cm2 may be easily achieved at a focus zone ofseveral millimeters in diameter with condenser optics,
which may enable us to use new material processes.
Part of this work was supported by a Grant-in-Aid
for Scientific Reserch C(#21560752) from The
Ministry of Education, Culture, Sports, Science andTechnology (MEXT) of Japan.

intensity[a.u.]

1.0

Xe rotating

Sn planar

0.8
0.6
0.4

Xe stationary

0.2
0.0

6

8

14
12
10
wavelength[nm]16FIG. 1. X-ray spectra from a rotating Xe target (solidline), a stationary Xe target (dotted line), and a planar
Sn target (dashed line) with a lens position of −5 mm.
1

EUV source for Lithography, edited by V. Bakshi(SPIE, Washington, 2005), p4.
2
Atsushi Shimoura et al, Appl. Phys. Lett. 72, 164(1998).
3
Takayasu Mochizuki, EUV R&D report (2003),
p105-114, sponsored by EUVA.
4
Akihisa Nagano et al, Appl. Phys. Lett. 90, 151502(2007).
5
Naoto Matsuo et al, Jpn. J. Appl. Phys. 46. (2007),
1061-1063.
6
Naoto Matsuo et al, J. Jpn Inst. Metals. 51(2010),1490-1493.
7
Shuji Miyamoto et al, Appl. Phys. Lett. 86, 261502(2005).
8
Keisuke Fukugaki et al, Rev. Sci. Instrum.77,
063114 (2006).
9
Takayasu Mochizuki, Proc. SPIE. 3886, 306 (2000).
10
Takayasu Mochizuki et al, Proc. SPIE. 4504, 87(2001).
11
S. A. van der Westen et al, ISMT Technology
Transfer Report, 04024490A-TR (2004).
12
K. Eidmann et al, Journal of X-ray Science andTechnology 2, 259-273 (1990).
13
Yuelin Li, G. D. Tsakiris, and R. Sigel, Rev. Sci.
Instrum. 66 (1), 80 January (1995).
14
S. Amano et al, Appl. Phys. B 101 ,213 (2010).
15
Sho Amano et al, Rev. Sci. Instrum 81, 023104(2010).
16
Francesco Flora, Luca Mezi et al, Proc. SPIE. 4504,
77 (2001).

32

Study on Powder Transport
Using Surface Acoustic Wave Actuator
Hikaru Tomita*, Tsunemasa Saiki**, Nozomu Araki*, Yuichi Utsumi** Laboratory of Advance Science and Technology for Industry, University of Hyogo, Japan** Hyogo Prefectural Institute of Technology, Japan
Abstract
Surface acoustic wave (SAW) devices are expected for micro total analysis systems, because
their structures are simple. We studied powder transport using SAWs. In this study, weinvestigated powder transport characteristic using SAWs as the relationship between the electric
power applied to a SAW actuator and the moving speed of powder. As a result, we found that thepossibility of controlling the amount of powder transport by adjusting the electric power applied to
the IDT and the application time was demonstrated and powder can be transported efficiently by
optimizing the IDT’s parameter.
Introduction
The manufacturing process of each device in a lab
on a chip must be simplified so that many small
devices can be integrated. Surface acoustic wave
(SAW) actuators with very simple structures haveattracted interest. Therefore, we fabricated SAW
drive pumps and created a continuous flow of liquidby optimizing interdigital transducers (IDTs) thatgenerate the SAWs [1]. Moreover, we fabricated ahigh efficiency mixing chip for synthesizing—one
that is operated only using the SAWs [2]. We also
speculated that powder can be transported by using
the SAWs because they had been found to movesolids [3]. If powder transport on a μTAS is possible,
we can apply it to transporting micro beads or toseparating a micro channel and to acquiring solidfragments precipitated in a liquid phase as the unit
chemical operation in solid synthesis. Processes likethese would enable extending the application range of
the SAW actuators. However, the process requires a
precise amount of bead movement. Thus, weinvestigated as transport characteristic using SAWs
the relationship between the electric power applied toa SAW actuator and the moving speed of powder.

In the experiment, a function generator created 1-kHz
burst waveforms consisting of 1000 cycles of 19.2
MHz sine waves, and an amplifier boosted the burst
waveform voltage. When the burst waveform voltage
was applied to an IDT electrode patterned on a
piezoelectric
substrate(127.8°y-rotated
x-propagating LiNbO3), SAWs were generated. The
SAWs propagated through the surface layer of thepiezoelectric substrate and arrived at a 10-mm3
powder located about 25 mm from the IDT. Here, weused two copper powders, whose specific gravity is
8.9, as shown in Fig. 2. The diameters of powder
are 10µm and 100µm. The powder then became
energized due to the SAWs, and it moved to theupper stream of the SAWs, as shown in the sequential
photographs taken using a high-definition camera ofFig. 3. Incidentally, the moving speed of the powder
can be obtained from photographs like these by using
the reaching distance and time.

Experimental Setup
Our experimental setup of powder movement using
SAWs is shown in Fig. 1.

10μm(a) 10µm copper powderHigh definition
camcorder

Function generator

SAWs
IDT
AmplifierMovingPower meter
25 mm

Powder(10 mm3)
Piezoelectric substrate(LiNbO 3 )100μm(b) 100µm copper powder

Figure 1. Experimental setup for observing
powder movement using SAWs.

Figure 2. SEM images of copper powder used
for experiment.

33

Moving speed S(mm/s)

50

Cu 10μm
Cu 100μm

40
30
20
10
0

0

500

1000

1500

Applie d e le c tric po w e r E( mW)

T rans portinge ffi c i e n c y [ m m / W s ]Figure 4. Relationship between moving speedof powder and electric power applied to IDT.

Figure 3. Sequential photographs of powder
movement using SAWs (Applied electric power:
420 mW).

40
30
20
10
0
0

100

200

Pi t ch P [ µm｣Experiment and results
We investigated the relationship between themoving speed of the powders and the electric power
applied to the IDT. Here, Stripline pitch of IDT is
200µｍ. The result is shown in Fig. 4. The moving
speed increased as the applied electric powerincreased. When 1440 mW of electric power wasapplied to the IDT，the moving speed of 10μm
powder was the third faster than it of 100μm powder.
Those result demonstrated the possibility ofcontrolling the amount of powder transport byadjusting the electric power applied to the IDT andthe application time.
Next, we investigated the relationship between
stripline pitch and transporting efficiency of powder.
Here, Stripline pitches of IDT are 40, 80 and 200μm
and powder is 10μm copper powder. The result isshown as Fig. 5. When the stripline pitch waschanged, the transporting efficiency of powder waschanged. When pitch was 80µm, the transporting
efficiency of powder was the highest. Those facts let
us to the conclusion that powder can be transported
efficiently by optimizing the IDT’s parameter.
Therefore, we will systematically investigate thisrelationship to design powder transport actuators.

Figure 5. Relationship between stripline pitch andtransporting efficiency of powder.
References[1] Y. Utsumi, T. Saiki and K. Okada, “Proposal of a
Novel Continuous Flow Pumping Operated by
Surface Acoustic Wave,” 12th International
Conference on Miniaturized Systems for Chemistry
and Life Sciences (μTAS2008), 715 (2008).
[2] T. Saiki, K. Okada and Y. Utsumi, “High
Efficiency Mixing and Pumping of Continuous
Liquid Flow using Surface-Acoustic-Wave”, 13th
International Conference on Miniaturized Systems for
Chemistry and Life Sciences (μTAS2009), 58 (2009).
[3] M. Kurosawa, M. Takahashi and T. Higuchi,“Ultrasonic Linear Motor using Surface Acoustic
Waves”, IEEE Transactions on Ultrasonics,
Ferroelectronics, and Frequency Control, 43, 901(1996)

34

HIGH-SENSITIVE DETECTION OF
POLYCHLORINATED BIPHENYL ON
THREE-DIMENSIONAL LAB-ON-A-CD
Hiroki Nose*, Tsukasa Azeta*, Yoshiaki Ukita**, Saki Kondo*, Chiwa Kataoka***, Yuzuru Takamura**,and Yuichi Utsumi***Laboratory of Advanced Science and Technology for Industory, University of Hyogo, JAPAN**School of Material Scinence, Japan Advanced Institute for the Science and Technology (JAIST), JAPAN***Carbuncle Bioscientech LLC., JAPAN
Abstract
This paper presents high-sensitivity detection of poly-chrolinatedbiphnenil in three-dimensional
lab-on-a-CD, which consists of multiple disks with three-dimensional microchannel networks. To
perform the automatic sequencing of competitive protocol, capillary barrier type passive valves
with vertically embedded capillary valve is designed and fabricated. We successfully demonstrated
the detection of poly-chrolinatedbiphenil. It is notable that the reproducibility of the detection isstrongly epending on the quality of scaffold and it is suggested that detection with concentration ofsample down to 0.01ng/ml is possible.
Introduction
The importance of fast and low cost immunoassay,
such as enzyme-linked immunosorbent assay(ELISA), has been recognized for advanced
diagnosis systems. Lab-on-a-CD has many
advantages, small sample volume consumption,
high-speed reaction, large-scale and parallel assays,
and compact system. However it has many issues tobe addressed. Especially, the development of highlyfunctionalized and highly-integrated microsystems
and high-sensitive and reliable accuracy is necessary
for wider applications. Moreover the automaticparallel operation of multiple microreactors is also
important for high-performance system to improvethe convenience and accuracy. The concept ofcentrifugal microfluidics realize fully automatedmicrofluidic systems without external syringe
pumping systems.
We have been proposed vertical microreactor stackwith multifunctional capillary bundle structure
realizing integrated system with multiple components
with different functions. The capillary bundle
structure has been used due to its multiple functions
and unique characteristics of high-efficiency
microreaction, high-efficiency mixing, and 3D
optical detection design.
As shown in the fig. 1(a), our lab-on-a-CD consistsof planer microchannel disk of PDMS and throughhole disk of PMMA disk. These disks are stacked andreversibly bonded together to construct 3D
microchannel network. As shown in fig. 1(b), stacked
structure contributes to enhance surface area for
antibody immobilization by using bundle-like
capillary structure and optical path length of thedetection reservoirs are also increased. The stack
structure of our device also contributes to reductionof space consumption of the each module byincreasing the thickness of reservoirs up to 700µm,
thus we succeeded in to integrate 10 microreactors on

an 8cm-disk. Figures 2 shows the photographs ofplaner microchannel disks of PDMS and throughhole PMMA disk, which fabricated by standard rapid
prototyping and deep X-ray lithography. As shownin fig. 2(b) bundle-likes capillary structure of squareshape capillaries (75µm in diameter) are formed on
the PMMA disks for the effective immobilization of
antibody.
(a)Middle layer

Top layer

Back side layer

Vent
4th reservoir(Stop)

Stacked 3D lab-on-a-CD

Closeuped

2nd reservoir(Wash)

Vent

3rd reservoir(Substrate)

1st reservoir(Analyte)
Waste
3D microreactor
antibody immobilized
solid surface

3D detection
reservoir(b)
To spectrometer

Vent
Top layer
Middle layer
Bottom layer

Flow inlight

Waste reservoir

Stacked opticaldetection reservoir

Vertical flow

Bundle-like capillary
structure (for antibody
immobilization)
Planar flow

Figure 1. The schematic illustration of threedimensional lab-on-a-CD. (a) Multiple layers ofdisks are stacked and bonded each other, to construct
3D microchannel networks. (b) Cross section of the
3D reaction chamber and optical detection reservoir.

35

(a)

limit is less than 0.01ng/ml, and the sensitivity iscomparable to the commercially available ELISA kit,
however it is expected that the further improvement
can be achieved by optimizing the protocol and thedevice.

(b)

Table 2 Obtained calibration curve by using threedimensional lab-on-a-CD. The signal of the enzyme
reaction is amplified by high-sensitive peroxidase
substrate(TMBZ).

Top disk
Back side disk
Middle layer disk
(PDMS with planer channel) (PMMA with through-hole) (PDMS with planer channel)

Inhibition constant (%)

100
80
60
40
20
0

Figure 2. (a)Photographs of fabricated disks of 3D
lab-on-a-CD. (b)SEM image of bundle-like capillary
structure for antibody immobilization.

Abosrbande at 450nm

0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
no6

Test 2

no7

Test 3no8

1

10

References
1. “A fully automated immunoassay from whole
blood on a disk” B. S. Lee et al., Lab Chip, 9,1548, (2009)
2. “Design of a compact disk-like microfluidic
platform for enzyme-linked immunosorbent
assay” S. Lay et al., Anal. Chem., 76, 1832,(2004)

Table 1 Reproducibility of the B0. The error of thetest is less than 5% in n=3

Test 10.1

PCB conc. (ng/ml)

Experiments and Results
To demonstrate the detection of PCB, bundle-like
capillary structure is immobilized with anti-PCB
antibody and blocked with BSA by off-chip
immobilization. Then the disk is reversibly bondedwith PDMS (also blocked) to construct 3D lab-on-aCD.
We found out the strong effect of micromachining
accuracy of the bundle-like capillary structure onto
the reproducibility of the assay. The Table 1 shows
simultaneously taken results of the three results oftests with same condition. As shown in Table 1, thereproducibility of the signal intensity is indeed good(error below the 5%) by using X-ray lithography withimproved machining accuracy.

0

0.01

Average

Average

We demonstrated competitive ELISA and Table 2
shows the result of the ELISA. The measurements
corresponding to each plot are simultaneously carriedout on same chip of three-dimensionally stacked
detection reservoirs by means of absorption
spectroscopy. As shown in Table 2, the decreasing
signal with analyte concentration clearly suggests
successful detection of PCB. Estimated detection

36

Fabrication of Integrated Magneto Impedance Sensor
for Medical Monitoring
Y. Yoritama1), M. Yoshida1), R. Takahashi1), T. Uchiyama2), A. Yamaguchi3), Y. Utsumi1)
1)
University of Hyogo, 2)Nagoya University, 3)Keio University
Abstract
For medical monitoring, we fabricate integrated Magneto Impedance (MI) sensor. The sensor ismagnetic sensor using skin effect. The fabricate process is complex consisting lithography
process, sputtering process and electroplating process. Therefore, we optimize the process
through repeated study of the chemical resistance of various materials and procedures, aimed atcompletion of the sensor.
Introduction
Recently, the relationship between heartbeat
fluctuations and diseases such as the diabetes
mellitus is very much noticed. By developing thesystem that always monitors the heartbeat, it isexpected that it may be connected for the early
detection of various diseases. The strength of thebiomagnetic field is about 10-10 to 10-13T. Generally,measurement of such a small magnetic field had tobe measured by the use SQUID (Superconducting
QUantum Interference Device). But this sensor has
the disadvantage that need to cool the sensor unit.
In contrast, MI (Magneto Impedance) sensors could
be used at room temperature, so it has attracting
attention at present. In addition Generally magnetic
sensor detect the magnetization of the magnetic
material to measure magnetic field. If you downsize
the sensor, the accurate measurement become
difficult by be affected demagnetizing field.
However MI sensor has a measurement principlethat doesn't use the magnetization of theferromagnetic. So the downsizing of sensor unit iseasy.

Fig.2 The image of our MI sensor
Fabrication Process
We designed the fabrication process of the sensor
by stacking multiple layers of insulation, andforming a three-dimensional coil pattern into
insulation layer.
The fabricated process consists of lithography
process, sputtering process and electroplatingprocess. The insulation layer (SU-8) of the internal
structure is formed by lithography process. Next,
we fabricate coil by electroplating, and pattern 2nd
insulation layer on it.
On the 2nd layer, sputtered high permeability alloy(Ni-Fe, permalloy). After that in the same way westacked an insulating layer on the brass substrateand formed the coil and the core in each layer.
Finally the sensor is removed from the brass
substrate and becomes it is completed. (Fig.3)

Resolution to detect
the magnetic field density [T]10-16 10-14 10-12 10-10 10-8 10-6 10-4 10-2 1
SQUID

Hall element
Flux
Magneto Resistive

Experiments and Results
We proved the fabricate process of MI sensor where
5 Insulation layers (SU-8), sputtering, and Au
plating had been used. As a result, it succeeded in
making the sensing element of Ni-Fe and the coil of
3D structure surrounding it on the brass substrate(Fig.4). In the future, measuring the characteristicsof the MI Sensor, aims to further improvements insensor and its fabrication process.

Magneto
Impedance
Magneto
Impedance

Fig.1 Magnetic sensor type and resolutions.

Sensor Design
The structure of our MI sensors is form the pickup
coil was wrapped around a ferromagnetic sensor
units (Fig.2). Pickup coil can detect of the signal
from the ferromagnet without noise. There is theinsulation layer between the ferromagnetic and the
pickup coil.

References[1] Berthold Rogge, Joachim Schulz：Magnetische
LIGA-Mikroaktoren, F &M.104(1996)37

[2] B.Rogge, J.Schulz, J.Mohr, A.Thommes and
W.Menz ： FULLY BATCH FABRICATEDMAGNETIC MICROATORS USING A TWOLAYER LIGA PROCESS, TRANDUCERS’95[3] K.Mohri、Y.Nakamura、T.Uchiyama、Y.Mohri、
Yu.Mohri 、 and Y.Inden ： Sendeing of Human
Micro-vibration Transmitted Along Solid Using
Pico-Tesla
Magneto-impedance
Sensor(pT-MISensor), PIERS ONLINE, VOL.6, NO.2,
2010

After plating Au
of the 4th layer[4] Tsuyosi Uchiyama, Shinsuke Nakayama, Kaneo
Mohli, and Kenichi Bushida： Biomagnetic field
detection
using
very
high
sensitivity
magnetoimpedance sensors for medical applications
Phys.Status Solidi A 206, No.4, 639-643(2009)/DOI
10.1002/pssa.200881251[5] Berkem Özkaya, Srinivasa Rao Saranu,
Senthilnathan Mohanan, and Ulrich Herr：Effects ofuniaxial stress on the magnetic properties of thinfilms and GMR sensors prepared on polyimide
substrates phys. stat sol (a) 205, No.8,
1876-1879(2008)/DOI 10.1002/pssa.200824036

Coil of 3D structure andsensing element made of Ni-Fe
Fig.4 The structures of fabricatedMI.sensor.

Fig.3 Outline of MI sensor fabrication process

38Fabricationof G oldN anoparticles AssembledN anovalley
for Surface Enhanced Raman Scattering
Takao Fukuoka, Daisuke Fukuoka, and Yuichi Utsumi
Laboratory of Advanced Science and Technology for Industry, University of Hyogo, Japan
Abstract
We developed a novel structure “Nanovalley” using the anisotropic self assembles of gold
nanoparticles on the nanoimprint template. The anisotropic noble metal nanostructures such as
linearly connected gold nanoparticles have localized plasmon resonance (LPR) of longitudinalmode which appears in near infrared region depending the aspect ratio of the nanostructures.
Enhance field of this LSR enables surface enhanced Raman scattering (SERS) with near infraredlaser irradiation. Sufficiently, the demonstration of rapid, sensitive, non-label and near infraredsensing of molecules was carried out with the fabricated unique anisotropic nanostructures.
1. Introduction
The anisotropic noble metal nanostructures
such as linearly connected gold nanoparticles have
localized plasmon resonance (LPR) of
longitudinal mode which appears in near infrared
region depending the aspect ratio of thenanostructures.1) Evoked enhance field of thisLSR enables surface enhanced Raman scattering(SERS) with near infrared laser irradiation. SERS
is interesting phenomenon that Raman scattering
intensity of the adsorbed molecules onto noble
metal nanostructure with nano scale roughness arelargely sensitized.2) Recently, SERS has broughtmuch attention as new method which is optimum
for narrow channel like microfluidic device.3,4)
There are, however, two problems to use SERS
in the microfluidic device. The first problem is tofabricate appropriate nanostructure with suitablelocalized plasmon resonance wavelength for
SERS in the narrow and limited region of micron
order channel. Second, it is required to detect
SERS signal rapidly to make use of characteristicof microfluidic flow analysis.
To resolve these issues, we developed newnanostructure “nanovalley”. In this nanovalley
structure, gold nanoparticles of 40 nm diameter
were assembled along grooves of 200 nm deep
which were fabricated on Polydimethylsiloxane(PDMS) by the nanoimprint method.

PDMS

Template
Step 1
Spin coating with PDMS resin on
the nanoimprint template

Ag Layer
Si Plate
Step 2
Stick the PDMS on Ag Layer/Si Plate

Dispersion of noble metal nanoparticles
or preaggregated noble metal nanoparticles

2. Experiments and Results
Commercial gold nanoparticles dispersion was
supplied from Archilys (Kyoto, Japan) since it was
specially designed to form chain-like aggregation
under the diffusion-limited aggregation, so that the
localized plasmon resonance (LPR) of theassembled gold nanoparticles in the nanovalley
was expected in the near infrared region.
The nanovalley structure were fabricated asshown in Fig. 1 ; spin coating of PDSM resin on
the nanoimprint template (step 1),
stick thePDMS on the silver layer coated on silicon plate(step 2), deposition of colloidal gold nanoparticles
onto the PDMS (step 3), and drying to makeassembles of gold nanoparticles on the
nanovalleys (step 4).5)

Step 3
Deposition of noble metal nanoparticles

Step 4The Nanovalleys with near infrared
plasmon resonanceFig. 1. Fabrication of the gold nanoparticles
assembled nanovalley structure.

39

The obtained nanovalley structure kept color
tone of reddish brown caused from LPR of
assembled gold nanoparticles (Fig. 2). This
reddish brown color seemed to be corresponding
to the LPR in near infrared region.1)

As for an in situ SERS measurement where thenanovalley structure was immersed in 4bpy
aqueous solution, SERS appeared within 5 s after
the immersion (Fig. 3 and 4). This very fast
response of SERS signal was desirable for highthroughput assay in microfluidic system. Fig. 4
also showed that the SERS intensity about 1600
cm-1 of 4bpy almost maintained constant value for
20 h.
The outstanding stability of SERS signal provesthat the SERS active nanostructure in the
nanovalley has been stable and unbreakable evenunder the wet condition.

Fig. 2. Appearance of the nanovalleys substratewith LPR in near infrared region.
3. SERS Activity of The Nanovalley
Evaluation of SERS activity of the nanovally was
carried out with Raman spectroscopy. This Raman
spectrometer equips incidental light with 785 nm,
100mW laser. As Raman probe molecule, 4,4'Bipyridine (4bpy) was used in aqueous solution.
In conventional SERS methods, it is essential thatthe sample solution is dropped and subsequently
evaporated on the nanostructure, before Raman
scattering of the deposited solid sample is collected.
However, the throughput of the flow analysis isinterrupted by the evaporation process in this "dropand dry" method.
To the contrary, the rapid signal response andlong term stability of SERS spectra of 4bpy
aqueous solution by 785 nm irradiation wereobserved. As shown in Fig. 3, 10 µM of 4bpy
solution was sufficiently detected, while 100 mM
concentration of 4bpy was required in normal
Raman measurement without the nanovalley.
These facts meant apparent enhancement morethan 104 at least was achieved by using theanisotropic gold nanoparticles assembles.

Fig. 4. SERS intensity response at 1600 cm-1
peak and long term stability using the
nanovalley.
4. Concluding remarks and perspectives
In conclusion, the availability of the
nanovalley structure as detector of microfluidic
device was sufficiently demonstrated. It is thoughtthat the unique nanovalley structure withanisotropic assembles of gold nanoparticles resultsin excellent effects for high throughput SERS
measurements.
References[1] M. Quiten and U. Kreibig: "Absorption und
Elastic Scattering of Light by Particle Aggregates",Appl. Optics, 32(30), pp.6173-6182, 1993.
[2] R. K. Chang and T. E. Furtak (Ed.): “Surface
Enhanced Raman Scattering”, Plenum, 1982.
[3] L. X. Chen and J. B. Choo : “Recent advances insurface-enhanced Raman scattering detection
technology for microfluidic chips”, Electrophoresis,
29(9), 1815-1828(2008).
[4] S. D. Hudson and G. Chumanov : “Bioanalyticalapplications of SERS (surface-enhanced Raman
spectroscopy)”, Anal. Bioanal. Chem., 394,.679-686(2009).
[5] T. Fukuoka, D. Fukuoka, Y. Mori, Y. Utsumi,“Fabrication of Gold Nanoparticles Assembled
Nanovalley for Surface Enhanced Raman Scattering”,
IEEJ Transactions on Electronics, Information and
Systems, 130(10), 1806-1810(2010).

Fig. 3. Typical SERS spectra of 10 µM 4bpy
aqueous solution with elapsed time after
immersion in sample solution.

40

Coherent Scatterometry Microscope ( CSM)
Hiroo Kinoshita, Masato Nakasuji, Testuo Harada, and Takeo Watanabe
Center for Center for EUVL, LASTI, University of Hyogo
1.

Introduction

This system is developed for the EUV mask inspection for thedefect size of 20 nm and below, and also for mask absorber pattern
CD measurement with high accuracy. To achieve these requirements,
reconsidering the principle and law of the optics, it is employed thatthe novel inspection method instead of the conventional optics for the
microscope. In this novel method, diffracted light intensity
distribution observed by an irradiated coherent light to the mask
absorber pattern is analyzed by a computer. Finally, using this novel
method, it can realize that the high accurate measurement method
Fig. 1. The principle of the EUV
coherent scattrometry microscope.
which has never been achieved in the paradigm for the smaller rule
for the advanced semiconductor devices. Since 2008, coherent
scatterometry microscope has been developing n our lab with collaborating with RIKEN and Osaka University.
2.

Coherent Scatterometry Microscope(a)Figure 1 shows the principle of the CSM. This system consistsof the light source, mask, the CCD camera for the soft x-ray, and-1次光
0次光
1st+1次光
order
-1st
order
0th
order
the computer. Defect can be inspected by the following method;
1) irradiating coherent light to the mask absorber pattern, 2)
observing the diffracted light intensity distribution by the CCD(b)camera, finally 3) absorber pattern images are reconstructed by acomputer algorithm of the iterative Fourier-Transform method
1 mfor the phase retrieval. In addition, absorber pattern width can beanalyzed by the diffracted light intensity of the periodic
Fig. 2. Observation results of theabsorber pattern, and it can be measured as a focal pattern
line-defect of 30-nm width pattern in 22
nm node; (a) diffracted light intensity
width on the wafer.
distributions, (b) reconstructed image
3.

Observation Results of the EUV Masks

In the EUV mask for 22 nm node, Figure 2(a) shows the diffracted light intensity image and reconstructed
image of L/S pattern with a 30-nm-width line-defect by the CCD camera distribution. The diffracted light signals
from the line-defect are observed between the 0th-order light from the ±1th-order lights from the periodic mask
pattern. As shown in Fig. 2(b), only line-defect image is reconstructed by remove the periodic pattern image
applying specific frequency filtering. In addition, the excellent repeatability 0.32 nm (3 ) for the CD
measurement of the line and space pattern is obtained, and the requirement of less than 0.65 nm (3 ) in the
ITRS is achieved.
4.

Mask Metrology System utilizing High-Order Harmonic EUV Light Source

Collaborating with RIKEN and Osaka University, a high-order harmonic laser for EUV light source on thebasis of the 59th harmonic ( = 13. 5nm) of the femto-second laser has been developing. Using this source,
since reducing a CSM inspection time by increasing the light source intensity to be 1000 times larger than theconventional light source, full field mask inspection can be achieved.
5.

Conclusions

Mask CD maeasurement becomes close to the practical technology level. For the mask defect inspection, thediffraction light intensity images of the various types of the mask defects have been analysing. In the future, 3-D
recontructed images of the mask could be achieved to obtain.

41

EUV Finished Mask Observation utilizing EUV
Microscope
Hiroo Kinoshita, Akifumi Tokimasa, Testuo Harada, and Takeo Watanabe
Center for Center for EUVL, LASTI, University of Hyogo
1.

Introduction
Mask defect reduction is one of thesignificant issues. Since 2002, bright fieldmask metrology system for the finished
EUV mask had been developed, and using
this system hp 100 nm absorber pattern,
pit-type phase defect size of 20 nm andthe depth of 2 nm on the blank mask weresucceed to obsorbed.

Fig. 1 System configuration of EUVM

2.

Configuration of the Experimetal Tool
Figure 1 shows the system configuration of the EUVM.
The light source is the bending magnet of BL3 beamline of
NewSUBARU
synchrotron
radiation
facility.
Schwarzschild optics (NA 0.3 and 30X) and the x-ray
zooming tude (20X～100X) are employed for the imaging
optics. The optical image of the mask pattern was focusedby the Schwarzschild optics on the CsI photocathode, thisimage was transfer to the electron image by the CsIphotocathode, and demagnified by the eletromagnetic lense
Fig. 2 Photograph of EUVM
of the X-ray zooming tube. And then the eletron image wastransfer to the optical image by the fluorescent plate after a micro-channel plate (MCP) and finally the image iscapture by the CCD camera. As the spatial resolution of CsI is 0.3 m, 20 nm size defect can be theoreticallyobserbed. The 172-nm-wavelength Xe lamp is attached on the loadlock chamber to remove contamination on asample before the observation. Figure 2 show the photograph of the EUVM.
3.

Obervation Results
Obervation results are shown in Fig. 3.

(a) hp480 nm Elbow(b) hp100 nm L&S(c) Phase defect on the mask blankFig.3. Observation results; (a), (b)absorber pattern, and (c) phase defect4.

Conclusions
Absorber pattern of the finished EUV mask and phase defects of mask blank can be observed by the EUVM.

42

EUV Interference Lithography
Takeo Watanabe, Yuya Yamaguchi, Takuro Urayama, Masato Nakasuji, Akifumi Tokimasa,
Naohiro Matsuda, Testuo Harada, Hiroo Kinoshita, and Takeo Watanabe
Center for EUVL, LASTI, University of Hyogo
1. Introduction
EUV interference lithographic system which can evaluate the resists for hp 22 nm, hp 16 nm, and hp 11 nm
nodes has been developing. Since in EUV interference lithography using light diffraction and interference,
replicated resist pattern with high accurate and high resolution can be obtained, it can be evaluated that
resolution and LWR of resist itself without other factors..
+1st orderThis
light EUV-IL exposure system is installed at the BL-9
beamline. Since the 10.8-long undulator (LU) is
0th order light
Pattern is replicated in this area
employed as a light source, spatial coherence is±1st order lightlarge and fine pattern can be replicated in the+ 1st order light
EUV light
0th order lightwhole exposure area. Up to now, 60-nm-pitch
0th order light-1st order lighttransmission grating pattern is fabricated, which ± 1st order lightcorresponds to hp 15 nm resist pattern on a
0th order lightwafer.
- 1st order light
2. Principle of EUV-IL
Resist Wafer
Grating
The intensity of the light produced from
Fig. 1. Principle of EUV-IL.
the LU is 1,000 times higher than thatfrom the bending magnet. In addition, the high coherent light is produced from the LU. By Young’sinterference experiment, it is confirmed that spatial coherence length larger than 1 mm. Figure 1
shows the configuration of the principle of EUV-IL using two window type transmission grating.
When the EUV light irradiates to the one grating window, the light diffracted into 0 th , -1 st , and +1 storders light. By two window grating, -1 st order light from one window grating and +1 st order lightfrom another window grating are interfere to produce the interference fringes on a wafer position.
Consequently resist pattern with a half pitch size of the transparent grating is replicated on a wafer.
The transmission grating is fabricated in the EUVL R&D center.
3. Exposure Results
Figure 2 shows the replicated resist pattern of the commercial resist ZEP-520A for electron utilizing EUV-IL.
SEM photographs of hp 22.5 nm, hp 20 nm, and hp 15 nm resist patterns were shown in this figure. We obtain
resist patterns with high contrast.

(a) hp 22.5 nm(b) hp 20 nm
Fig. 2. Exposure results obtained by EUV-IL(c) hp 15 nm

4. Conclusions
EUV-IL system has large enough coherence length. Uniform and high contrast resist patterns are replicated inwhole exposed area. And it is confirmed that EUV-IL is effective for the resist evaluation of hp 22 nm and below.

43In-situ contamination thickness measurement in the EUV
resist outgassing environment
Takeo Watanabe, Naohiro Matsuda, Tetsuo Harada, and Hiroo Kinoshita
Center for EUVL, LASTI, University of Hyogo
1.

Introduction
Photograph of the novel resist evaluation system

EUV light
Exposure in EUVL requires vacuum environment. Since, in
Xe lamp
EUVL during the exposure, the carbon contamination is adhered
Polarizer
on the optics and the mask, Mo/Si multilayer (ML) reflectivity ofAnalyzer
the optics and the mask, and replicated pattern width on a wafer
Witness sample
could be changed. The carbon contamination mainly own to theCCG
decomposition reaction of the hydrocarbon gas species by EUV
irradiation. Although many researches were carried out to reducethe contamination, it has not been clarified yet that theFig. 1. Photograph of the novel
relationship between the outgas species of the hydrocarbons andresist evaluation system.
the carbon contamination adhesion thickness on ML. Thus, thein-situ thickness-measuring system for the carbon contamination due to the resist outgas during the EUV
irradiation.
Resist Thickness 90 nm
Base pressure 1.5 ×10 -5 Pa

Experimental

6.00E -06
Hydro Carbon Partial Pressure (Pa)2.

SR beam current 220 mA with top -up operation@1GeV electron energy of the storage ring

4.

(nm)

Cabon contamination thickness

5.00E -06
Figure 1 shows the photograph of this system. EUV light
4.00E -06
irradiates to a witness sample of a Mo/Si ML mirror at the
3.00E -06
normal incident angle of 6 degrees, and the EUV light irradiates
2.00E -06
to the resist sample. The vacuum pressure is measured by the
Exposure
Exposure
1.00E -06
pressure gauge, and the outgas species are measured by the
0.00E+00
quadruple mass spectrometer (Qmass). Simultaneously, the
0
50
100
150
200
250
300
contamination adhesion thickness is measured by the in-situ
Time (s)ellipsometer. Xe lamp is employed as a light source of theFig. 2. Hydrocarbon partial pressure
ellipsometer. The Xe light is led to the witness sample throughmeasured by Qmass.
the polarizer and then the reflected light is led to monochrometerSRbeam current
220 mA with top-up
operationV.S. Exposure time
Carboncontamination
thicknessthrough the analyzer. Finally the polarization spectra of the4
Deposition rate 0.011 nm/min
wavelength from 250 nm to 800 nm was analyzed to measure
3.5
the adhesion thickness of the carbon contamination.
3
2.5
3. Results and Discussions
2
Figure 2 shows the hydrocarbon partial pressure time
1.5
1
dependency of the hydrocarbon. Since the partial pressure
0.5
becomes high during the EUV irradiation and the partial
0pressure becomes small during the non-exposure, hydrocarbon
0
100
200
300
Time (min)outgas species produced during the EUV irradiation exposure
to the resist. Figure 3 shows the time dependency of the carbon
Fig.3 EUV irradiation time dependency ofcontamination thickness measured by the in-situ ellipsometer.
carbon contamination deposition
In the thickness measurement, multilayer structure of thewitness sample was taken in an account. The thickness measurement result by the in-situ ellipsometer has a good
agreement with that by the atomic force microscope (AFM), by the nanometrcis thickness measurement system,and the reflectometer at the BL10 beamline in NewSUBARU. As the results, it is confirmed that theeffectiveness of the carbon contamination thickness utilizing the in-situ ellipsometer.

Conclusions

It is confirmed that the effectiveness of the carbon contamination thickness utilizing the in-situ ellipsometer.
In addition, it is confirmed that the relationship between the resist outgas species by EUV irradiation and theadhesion thickness of the carbon contamination under the EUV light intensity required for the HVM.

44

Optical element evaluation system
Tetsuo Harada, Takeo Watanabe, and Hiroo Kinosh8ita
Center for EUVL, LASTI, University of Hyogo
1.

Introduction
Multilayer
reflectivity
measurement plays an significant
role of the lithographic throughput intheEUVL
technology.
At
NewSUBARU, since 2000, thereflectometer beamline for themultilayer reflectivity measurement
had been constructed, and thisbeamline has been opened forcommon use for two companies ofthe mask blanks.

Fig. 1. Configuration of the reflectometer at BL-10 beamline

2.

System Configuration
Figure 1 shows the configuration of BL-10 beamline. Monk-Gillieson type monochrometer, on the basis of
the variable-line-spacing plane-grating-monochrometer (VLS-PGM) is employed as a monochrometer. Influenceof the higher order light is reduced by a Si filter.
By adjusting the inclination angle of the monochrometer , the incident light can be monochromated to thewavelength from 6.0 nm to 24 nm using the VLS-PGM with the line density of 600 lines/mm. In addition, in thecase of the VLS-PGM with the line density of 1800 lines/mm line, it can be monochromated to the wavelengthfrom 3.0 nm to 8 nm and the K absorption edge of the oxygen can be analyzed. The reflectometer consists of the-2 stage, and x-y stage is attached on the -stage which can cover the whole mask area size of 150×150 mm2
for the reflectivity measurement. Since the - and 2- stages can be moved by the individual stepping motors
through ferrofluidic seal from outside the vacuum chamber, high speed and high accurate movement of 1 to 89
degrees for the mask incident angle can be controlled.
703.

Berkeley
New SUBARU BL-1060
50
Reflectivity [%]Example of the Reflectivity Measurement
Figure 2 shows the reflectivity spectra of same
Mo/Si ML sample at NewSUABRU and Advanced
Light Source (ALS). From this figure, it can be
confirmed that the reflectivity spectrum measured at
BL10 beamline at NewSUBARU is almost same asthat measured at ALS. In addition, comparison resultsof the centroid wavelength and the reflectivity for thatare shown in Table 1. As results, the reflectivity
measurement accuracy becomes to be a world
standard.

40
30

20
10

0
13.0

13.1

13.2

13.3

13.4

13.5

13.6

13.7

13.8

13.9

14.0

Wavelength [nm]Fig. 2. Reflectivity spectra measured at NewSUBARU

Table 1. Measurement accuracy comparison with NewSUBARU and ALS
CWHM
Measurement accuracy of the（Measurement accuracy of the centroid wavelength） reflectivity
ALS
0.007 nm
0.08%
NewSUBARU 0.0064 nm
0.11%

45

Classification of Near-Edge X-ray Absorption Fine
Structure Spectra of Si-containing DLC Thin Films
Kazuhiro Kandaa,*, Masahito Niibea, Akira Wadab, Haruhiko Itob, Tsuneo Suzukic, and Hidetoshi Saitohba
LASTI, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205, Japanb
Department of Materials Science and Technology, Nagaoka University of Technology,1603-1 Kamitomioka Nagaoka, 940-2188, Japanc
Extreme Energy-Density Research Institute, Nagaoka University of Technology,1603-1 Kamitomioka Nagaoka, 940-2188, Japan
Abstract
Structural analysis was performed on the 23 kinds of silicon-containing diamond-like carbon(Si-DLC) films fabricated with various synthesis methods by the measurement of carbon K-edgenear-edge x-ray absorption fine structure (NEXAFS) using synchrotron radiation. Observed
NEXAFS spectra of Si-DLC films were classified to 4 kinds of type. The shrinking and shift of* band and broadening of * peak were founded. The change of C K-edge NEXAFS spectrumof Si-DLC film was strongly related to the content of Si in the Si-DLC film.
1. Introduction
One of the important issues for the use of DLC films as wear-resistive coatings is their internal stress.
The containing of hetero-atom in DLC films posses the potential to improve wear performance. However,comprehensive analysis of C K-edge NEXAFS spectra has not investigated as for many Si-DLC films fabricatedwith various synthesis methods. In the present study, local structures of 23 kinds of Si-DLC films were studied
using C K-edge NEXAFS spectroscopy . The elementary analysis was performed from the combination of
Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA).
2. Experimental
The NEXAFS measurement was performed at theBL05B and BL09A of NewSUBARU in the University of
Hyogo. Synchrotron radiation dispersed by a invalid spacing
planer grating monochromator was irradiated on the sample
film at 54.7° (magic angle) with respect to surface normal ofsamples. The electrons coming from the sample weredetected in the total electron yield (TEY) mode. The RBS
and ERDA with MeV-He+ irradiation were performed using
an electrostatic accelerator (NT-1700HS: Nisshin-High
Voltage Co.) located at the Extreme Energy Density
Research Institute, in Nagaoka University of Technology.
The He+ ions accelerated to 2.5 MeV were used as incident
beam at 72° with respect to surface normal of samples.
3. Results and Discussion
The NEXAFS spectra of Si-DLC films can beclassified to 4 types by its spectral profile as shown Fig. 1.
Figure 2 depicts NEXAFS spectra of a typical DLC film,
which contains only carbon and hydrogen without Si andother hetro-elements, and -SiC powder as references. A
sharp peak was observed at 285.4 eV in the NEXAFS
spectrum of typical DLC film. This peak is originated fromthe transition from 1s orbital to unoccupied  orbital. In
other words, this peak indicates the sp2 hybridized orbital,
therefore this peak is not observed in the NEXAFS
spectrum of diamond. The broad band at around 293 eV isFig. 1 The C K-edge NEXAFS spectra
generated from the transition from 1s orbital to unoccupiedof Si-DLC films
 orbital. In this region of NEXAFS spectra of diamond andgraphite, structural peaks were observed, but in the spectra of DLC film, only broad band was observed due to its

46

amorphous structure. In the NEXAFS spectrum of -SiC powder, asharp peak was observed at 289 eV. This peak was assignable to the1s* transition generated from the carbon bonded to silicon.
In the type 1 of NEXAFS spectra of Si-DLC films, spectral
profile resembled that of typical DLC film without hetro-atoms. In thetype 2 of NEXAFS spectra of Si-DLC films, the shrinking of the band
generated from the 1s* transition was found. In the type 3 of
NEXAFS spectra of Si-DLC films, the shrinking of 1s* band
advanced and this band was shifted to lower energy side. In addition,
the peak generated from the 1s* transition was found to broaden. In
the type 4 of NEXAFS spectra of Si-DLC films, the 1s* peakcannot be observed as isolated peak by the advancement of theshrinking and shift of * band.
Figure 3 depicts the relation of type of NEXAFS spectrum of
Si-DLC film with elementary composition determined by themeasurement of the combination of RBS and ERDA techniques. The
type of NEXAFS spectrum increased from 1 to 4 with increasing Si
content in Si-DLC film. The boundary between type 1 and type 2 was
located at 6 % of Si content. Type 3 was appeared in the region where
Si content was larger than 10 % and type 4 was appeared beyond 25 %Fig. 2 The C K-edge NEXAFS
of Si content. In other words, the type of NEXAFS spectrum increased
spectra of a) a typical DLC film
from 1 to 4 with increasing Si content in Si-DLC film.
and b) -SiC powder
In addition, the type of NEXAFS spectrum also
increased with H content. This indicated that the typeof NEXAFS spectrum is determined by the Si/(Si+C)
rather than Si/(Si+C+H). From these observations,the shrinking and shift of * band was interpreted
that the 1s* transition of C-C site was altered tothat of C-Si site with the increase of Si content in thefilm. In the type 3 of NEXAFS spectra of Si-DLC
films, the broadening of 1s* peak was observed
as described above. The peak width of 1s*transition was plotted against Si-content in Fig. 4.
The peak width of 1s* transition slightly
increased with Si-content. It can be considered thatthe peak width of 1s* peak was broadened by theFig. 3 The relation of type of NEXAFS spectrum of
appearance of C=C-Si site with Si-content in the
Si-DLC film with elementary composition; open
Si-DLC film.
circle: type 1, open square: type 2, closed circle: type3,.and closed square: type 4.

peak width / eV(FWHM)

4. Conclusions
The C K-edge NEXAFS spectra of 23
kinds of Si-DLC film fabricated by various synthesis
methods were using synchrotron radiation. C K-edge
NEXAFS spectra of Si-DLC films were classified to
4 kinds of type. Shrinking of σ* band was due to thechange from σ(C–C) to σ(C–Si). Broadening of 
peak can be considered to increase of C=C–Si site.
The type of C K-edge NEXAFS spectrum of Si-DLC
film was strongly related to the content of Si.
Classification of Si-DLC NEXAFS spectrum can beconsidered to good index for the classification of
Si-DLC films.

2
1.8
1.6
1.4
1.2
0

20
30
Si / at%Fig. 4 The dependence of the peak width of1s* transition against Si-content in the
Si-DLC film.

47

10

Sulfur L3.2-edge XANES spectroscopy reveals differencesin sulfur speciation of reference S compounds
Toko Tanikawa1) , Kazuhiro Kanda2), Masaharu Uemura3), Takayuki Hasegawa3),
Mizue Ohashi4), Yashuhiro Hirano5)
1) Kansai Research Center, Forestry and Forest Products Research Institute, Nagai-kyutaro, Momoyama,
Fushimi, Kyoto; 2) Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2
Koto, Kamigori-cho, Ako-gun, Hyogo; 3) Synchrotron Analysis L.L.C., 3-1-2 Koto, Kamigori-cho, Ako-gun,
Hyogo; 4) School of Human Science and Environment, University of Hyogo, 1-1-12 Shinzaike-Honcho, Himeji,
Hyogo; 5) Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi
Abstract
In forest soils, sulfur exists in a large variety of organic and inorganic forms with different electronic oxidation
states, ranging from -2 to +6. Because an excess S from atmospheric depositions is supposed to disturb soil
ecosystems, and the disturbance would be repressed by a soil sulfur retention function, it is needed to clear sulfur
retention mechanism. An advanced technique, X-ray absorption near-edge structure (XANES) has recently been
adapted for S fractionations in environmental samples. Previous studies reported that the technique was superior
to traditional wet-chemical methods for the S fractionations. Thus, we examined whether S L-edge XANES isable to fractionate 6 analysis-grade reference S compounds by different oxidation states or not. The differencesin compound structures were reflected clearly in the spectra at BL05B. These results suggest that a beamline
BL05B can be used reliably to separate and quantify sulfur species with different oxidation states.
Introduction
Sulfur, an essential element for the growth of plants and microorganisms, continuously cycles between organicand inorganic forms in the soil. An excess S from atmospheric depositions is supposed to disturb soil ecosystems.
The soil retention of organic S is a key process regulating a S cycling in terrestrial ecosystems, and the process
can diminish or delay the net acidification of soils. In general, the soil organic S is classified into hydroiodic
acid-reducible and -nonreducible S, both of which are considered to represent an ester sulfate-S and a carbon(C)-bonded S, respectively. The former is corresponded to the soil organic S in highly oxidized states, and thelatter is corresponded to highly reduced and intermediate oxidation states. These traits were determined by arecent advanced technique, S K-edge XANES spectroscopy. The traditional classification of organic S based onbond classes might not have an enough sensitivity to distinguish between labile and refractory organic S forms.
Detail fractionations of the organic S using the advanced techniques are needed to clarify the mechanism oforganic S retentions in forest soils. Although the K-edge XANES is not be able to detect the difference between
organic and inorganic S, a L-edge analysis is expect to be suitable for S fractionations. However, the applicationof soil sulfur fractionation using L-edge XANES analysis has not been reported yet. To establish a S
fractionation method, we examined whether the S L-edge XANES is available to fractionate 6 analysis-grade
reference S compounds by different oxidation states or not.

Intensity (arbitrary unit)

Intensity (arbitrary unit)

Experiments and Results
Analysis-grade reference S compounds; L-methione DL-methionine sulfoxide, sodium sulfite, ethyl phenyl
sulfone, L-cysteric acid, and sodium dodecyl sulfate were used for the XANES analysis at either beamlines of
BL05B in the NewSUBARU synchrotron radiation facility, University of Hyogo. The spectra obtained by a total
electron yield method at BL05B clearly reflected compound structures in the references, suggesting that BL05B
was suitable for S fractionations.
Because the differences in the
1.4
1.2
DL-methionine sulfoxide
compound structures were reflected
L-methionine
1.2
1
clearly in the spectra at BL05B, thisbeamline can be used reliably to10.8
separate and quantify sulfur species
0.8with different oxidation states.
a
b
160

170
180
190
Photon energy (eV)

Grating=100 l/mm
Slit width=50 m, Insident angle=90°

0.6

160

170
180
190
Photon energy (eV)

Grating=100 l/mm
Slit width=50 m, Insident angle=90°

Fig.1 Sulfur L3,2-edge XANES spectra obtained by total electron yield method at beamline BL05B.
a) L-methione; b) DL-methionine sulfoxide

48The Present Status of Material Analysis Beamline
at BL05 for Industrial Enterprises
T. Hasegawa1, M. Uemura1, M. Motoyama2 and K. Kanda2
1 Synchrotron Analysis L.L.C., Hyogo-ku, Kobe, Hyogo 652-0863 Japan
2 University of Hyogo, Kamigori, Ako, Hyogo 678-1205 Japan
Abstract
A material analysis beamline for the industrial enterprises’ use was completed at BL05 in March
2008. BL05 consists of two branch lines, one is a double crystal monochromator beamline(BL05A) for the use in the higher-energy region (1300-4000 eV) and the other is a varied line
spacing plane grating (VLSPG) monochromator beamline (BL05B) for the use in the lower-energy
region (50-1300 eV). These two branch lines can be operated simultaneously. The whole usefulenergy range of the BL05 is the soft X-ray region from 50 to 4000 eV. The X-ray absorption finestructure (XAFS) measurements in the total electron yield (TEY) and fluorescence yield (FLY)
can be performed at BL05A and BL05B. In addition, the X-ray photoelectron spectra (XPS) canbe measured at BL05B.
Introduction
A material analysis beamline for the industrial
enterprises’ use was completed at BL05 in March
2008 [1]. The light source of BL05 is the bending
magnet, which can provide the photon in the region
up to 4000 eV. BL05 consists of two branch lines forthe use in the higher-energy region (1300-4000 eV)
and lower-energy region (50-1300 eV), respectively.
The whole useful energy range of the BL05 is the soft
X-ray region from 50 to 4000 eV and X-ray
absorption spectrum can be measured with ahigh-energy resolution. Because the incident beamfrom the bending magnet is provided for two branchlines through the different windows of mask, these
two branch lines can be operated simultaneously.
BL05 will be managed and maintained by the
Synchrotron Analysis L.L.C. (SALLC), which iscomposed of the industrial companies, in cooperation
with the staffs of the Laboratory of Advanced
Scienece and Technology for Industry in Universityof Hyogo. Industrial users can be assisted by staffs of
SALLC in the measurement at BL05. In this paper,
we will introduce BL05 and report recent activities,
which succeeds in the improvement of the opticalalignment of BL05B.

Specifications of BL05B
Fig.2 shows optical layout of BL05B. The lightbeam is focused on the entrance slit S1 horizontallyby the cylindrical mirror M0 and vertically by thecylindrical mirror M1. The constant-deviation
monochromator consisting of a demagnifying
spherical mirror and VLSPG, which can provide tohigh resolution, simple wavelength scanning with
fixed slits, was mounted on BL05B. The including
angle of the monochromator is 175. The grating
holder of VLSPG can keep three gratings (100-, 300and 800-lines/mm) and change the active grating
without
brakingvacuumcondition.
Twomeasurement chambers are prepared at the end
station of BL05B. The XAFS spectra in the total
electron yield mode and fluorescence XAFS spectrausing SSD (EDAX) can be measurement in thehigh vacuum chamber. In addition, the X-ray
photoelectron spectra (XPS) using spherical electron
analyzer (VG Scienta, R3000) can be measured in theultra high vacuum chamber. These chambers can be
replaced each other within 1 hour. It can keep 16
samples of 25 mm corner in the respective chamber.

Specifications of BL05A
Toroidal mirrors are used as a pre-mirror (M0)and a focusing mirror (M1) of BL05A, for the
purpose to introduce a high-photon flux to the end
station (Fig.1). InSb (111) crystals and Si (111)crystals are prepared for a Golovchenko-type double
crystal monochromator. The XAFS measurements inthe total electron yield (TEY) and fluorescence yield(FLY) using SDD (SII, Vortex) can be performed.
The SDD can operated without liquid nitrogen.The
fluorescence XAFS spectra can be measured samples
at the under an atmospheric pressure by the
replacement of an end station to He using Be window.
It can keep 8 samples of 25 mm corner in thechamber because of industrial use.

Radiation
ShieldBL05A
Toroidal

M0
Bending
Magnet0

Toroidal

S0

M1

Double Crystal
Monochromator
3.65

11.0 11.65

Fig.1 Optical layout of BL05A.

49

14.65

Sample16.65 〔m〕

BL05B
Cylindrical

Radiation
ShieldM0

Plane VLS
grating

Entrance slit

S0 Cylindrical
S1
M1

Bending
MagnetExit slit

S2

Toroidal

Mf

SH

M2

4-jaw
aperture

Spherical

0

4.0

10.5

14.0

21.0 21.5

28.0

Sample4WS

Hartman32.0 〔m〕

30.0

Fig.2 Optical layout of BL05B.

Measurement
We did readjustment of the optical mirror andmeasured standard samples by means of the TEY
method in BL05B. Fig.3-5 show the absorption
spectra which are obtained in each grating, 100- or
300- or 800-lines/mm, boron K-edge, calcium andnickel L3,2-edge near-edge X-ray absorption finestructure (NEXAFS) spectra of hexagonal boron

Intensity (arbitrary unit)*nitride (h-BN), calcium fluoride (CaF2) powder andNickel (Ni) sheet. The spectrum have beennormalized to I0 and had a linear pre-edge
background removed. After the optical adjusting (slitwidth : 50 μm), improvement of resolution is verified
by comparison with before the optical adjusting (slitwidth : 200 μm). For h-BN, an intense peak at 192 eV
and a structured absorption band of 197-201 eV are
assigned to the transitions from B1s to theunoccupied B2p π* and σ* states, respectively in
Fig.3 [2]. Additionally, the calcium L3,2-edge spectral
shape of CaF2 almost corresponds to the spectrum
reported by Naftel et al. [3]. The nickel L3,2
absorption peaks are observed at 853 and 871 eV,
respectively [4].

Slit Width
50 m200 m190

L3

Intensity (arbitrary unit)*

200
Photon Energy (eV)

Grating=100 lines/mm, Incident Angle=45 °Fig.3 h-BN B K-edge NEXAFS spectra.

L2

840
Intensity (arbitrary unit)

L3

L2 Slit Width

50 m200 mSlit Width
50 m200 m850
860
870
Photon Energy (eV)880

Grating=800 lines/mm, Incident Angle=45 °Fig.5 Ni L3,2-edge NEXAFS spectra.

340

350
Photon Energy (eV)References[1] T.Hasegawa et al., Advances in X-ray Chem.
Anal. Jpn., 41, pp.99-106 (2010) [in Japanese].
[2] I.Jiménez, A.F.Jankowski, L.J.Terminello, D.G.J.
Sutherland, J.A.Carlisle, G.L.Doll, W.M.Tong, D.K.
Shuh, F.J.Himpsel, Phys. Rev., B55, 12027 (1997).
[3] S.J.Naftel, T.K.Sham, Y.M.Yiu, B.W.Yates, J.
Synchrotron Rad., 8, 255 (2001).
[4] J.A.Bearden, A.F.Burr, Rev. Mod. Phys., 39, 125(1967).

360

Grating=300 lines/mm, Incident Angle=45 °Fig.4 CaF2 Ca L3,2-edge NEXAFS spectra.

50

Low-Temperature Crystallization of a-Si, a-Ge anda-SiGe Films by Soft X-ray Irradiation
Akira Heya, Yuki Nonomura, Shota Kino, Kazuhiro Kanda and Naoto Matsuo
University of Hyogo
Abstract
We investigated novel low-temperature crystallization of a-Ge, a-Si and a-SiGe films by the SR
soft X-ray irradiation at storage ring current of 25-220 mA and dose quantity of 50 mA･h. The
relationship between electron excitation followed by atom migration process, thermal process andthe storage-ring current are investigated. Crystallization of SiGe caused by the vibration due to soft
X-ray irradiation is effective as compared with the thermal annealing.
Introduction
Flexible organic light emitting diode (OLED) display is one of the most expected displays for next
generation because of its light weight and flexibility. Polycrystalline Si, Ge and SiGe films on thepolymer substrate are attractive for thin film transistor (TFT) in flexible flat panel display and solar cell. The
process temperature to produce the poly-Si, Ge and SiGe films by excimer laser annealing is too high toapply the plastic substrate. We have proposed a novel low temperature crystallization method of soft X-ray
irradiation using short undulator BL07A of NewSUBARU of SR facilities. In this study, we investigate thecrystallization mechanism of a-Si, a-Ge and a-SiGe irradiated using soft X-ray undulator source.
Experiments and Results
a-Si films was deposited on SiO2/glass substrate by PECVD and a-Ge and a-SiGe were deposited by
MBD (deposition rate: 0.02 nm/s, base pressure: ~10-10 Torr). The thickness of a-Ge, a-Si and a-SiGe was 50
nm. The storage ring energy, storage ring current, photon energy and dose quantity were 1.0 GeV, 25 to 220
mA, 115 eV and 50 mA･h (Irradiation times was 30min in case of 100mA), respectively. The characteristicsof the film were measured by Raman spectroscopy. Raman spectroscopy condition that laser power andobject lens were 1.5 mW and 100 times. In the case of Si films, the crystalline fraction was determined fromthe areal ratio of the signal due to the crystalline phase around 521 cm-1 to the sum of the signals due to boththe crystalline phase and the amorphous phase around 480 cm-1.
Figure 1 shows crystalline fraction of Si, Ge SiGe films as a function of storage-ring current. The
crystallization threshold of Ge sample was 75 mA. Sample
temperature and crystalline fraction were 420°C and 80%,
respectively. On the other hand, Si sample did not crystallize at 75
mA, although the sample temperature rised up to 390°C.
Crystalline fraction at the center of Ge and Si were 80 % and 0 %,respectively. The difference of crystalline fraction between a-Si
and a-Ge is thought to be due to the energy band gap (Eg) of Ge
and Si. The electron excitation of Ge was 107 times larger than Si.
The density of state in the valence band of Si and Ge was almost
the same. Therefore, it is thought that electron in valence band of
Ge is excited easily, the sample temperature becomes high by Fig. 1. Crystalline fraction of Si, Ge
SiGe films as a function ofrelaxation process of electron.
Figure 2 shows Raman spectra of SiGe with irradiation area at storage-ring current.
220mA and non irradiation area. The crystalline fraction of Si-Si,
Ge-Ge and Si-Ge were 57%, 67% and 86%, respectively. It is
known that binding energy of Ge-Ge and Si-Si are 2.8 eV and 3.4
eV, respectively. Atomic migration of Ge atoms is influenced bysoft X-ray irradiation more strongly than Si atoms. Therefore, it iseasy to form quasi-nuclei of Ge compared with Si.
For SiGe, the crystalline fraction estimated from Ge-Ge peak islarger than that of Si-Si peak. The Si-Si bond is stronger than the
Ge-Ge bond. Therefore, it is easy to make quasi nuclei of Ge.
Crystallization of SiGe caused by the vibration due to soft X-ray Fig. 2. Raman spectra at irradiatedmight be effective compared with thermal annealing.
and non -irradiated area of SiGe film.

51

Photoelectron Spectroscopy Study of the Valence Band
Region in Diamond-Like Carbon Thin Films
Yuichi Haruyama1, Teruyuki Kitagawa1, Shinji Matsui1, Noriaki Toyoda2, and Isao Yamada2
1
Laboratory of Advanced Science and Technology for Industry, University of Hyogo
2
Graduate School of Engineering, University of Hyogo
Abstract
Photoelectron spectra of the valence band region in diamond, diamond-like carbon (DLC), glassy
carbon, and graphite were measured in order to investigate the influence of the carbon atom
coordination on photoelectron spectra. Differences in the photoelectron spectra were observed,
depending on the coordination of the carbon atoms. The photoelectron spectra for DLC and glassy
carbon were compared to those simulated using the photoelectron spectra for diamond andgraphite. From this comparison, it was found that the photoelectron spectra in DLC could not be
simply reproduced using those for diamond and graphite. In addition, the photoelectron spectra of
the valence band region in DLC were compared to the density of states previously calculated using
the molecular dynamics method.
Introduction
Diamond-like carbon (DLC) is an amorphous material composed of sp2 and sp3 carbon, with negligible
presence of sp carbon. DLC thin films have very interesting properties, such as high hardness, low friction
coefficient, and chemical inertness, and therefore, studies on DLC films have attracted significant attention
for a potentially wide range of applications. The properties of DLC films are related to the coordination of C
atoms, such as sp2 and sp3 carbon [1]. Estimation of the sp2 content is one of the important subjects in studies
on DLC films; the sp2 content in DLC films has been determined using electron energy loss spectroscopy andnear-edge X-ray absorption fine structure (NEXAFS) studies [1]. Recently, the sp2 and sp3 content of DLC
films was directly evaluated from X-ray photoelectron spectroscopy (XPS) spectra of the C 1s core-level
region. Although photoelectron spectroscopy studies of the valence band region are important to investigate
the electronic structure, such as the density of states, the orbital characteristic, there are few reports on
photoelectron spectra of the valence band region in DLC. In particular, the evolution of photoelectron spectraof the valence band region as a function of the sp2content has not been clarified.
Experiments and Results
DLC films obtained using gas cluster ion beam (GCIB) assisted deposition were formed by irradiating Ar
cluster ion beams. Three DLC films were formed with acceleration energy of the Ar cluster ions of 5, 7, and 9
kV. Glassy carbon, graphite, and diamond were also prepared for comparison. In our previous XPS study of
the C 1s core level in DLC films formed by GCIB deposition [1], the sp2 and sp3 content were estimated.
With increasing acceleration energy of the Ar cluster ions, from 5 to 9 kV, the sp2 content in the DLC films
increased from 49 to 62 %. Similarly, the sp2 and sp3 content in the glassy carbon were estimated to be 95 and
5 %, respectively. For the DLC films formed by the GCIB deposition, the sp2 content was estimated [1].
Figure 1 shows the photoelectron spectra of the valence band region in graphite, glassy carbon, threedifferent DLC films, and diamond. All the photoelectron spectra are composed of a dominant feature between
12 and 0 eV and a small feature between 22 and 12 eV. As discussed later, the features between 22 and 12 eV
and between 12 and 0 eV are predominantly derived from the C 2s and C 2p states, respectively. In the caseof graphite, several peaks were observed at ~19.0, ~13.0, ~10.0, ~7.8, ~5.5, and ~3.0 eV. In glassy carbon,
three peaks at ~19.0, ~13.0, and ~7.8 eV were clearly observed. However, the other three peaks at ~10.0,~5.5, and ~3.0 eV were barely visible. In the case of the three DLC films, five peaks were observed, at ~19.0,~13.0, ~10.0, ~7.0, and ~3.8 eV. The intensity of the peak at ~10.0 eV was higher than that in graphite andglassy carbon. Also, the intensity of the peak at ~3.0 eV decreased compared to that in graphite and glassy
carbon. Therefore, a clear peak at ~3.0 eV was not observed. A peak at ~3.8 eV instead of ~3.0 eV appearedin the spectra for the three DLC films. With decreasing acceleration energy of the Ar cluster ions from 9 to 5
kV, the feature between 12 and 0 eV in DLC films was broader. In diamond, several peaks were observed, at~19.0, ~16.5, ~13.0, ~10.0, ~6.5, and ~3.8 eV. We discuss the evolution of the photoelectron spectra in thevalence band region as a function of the sp2 content. At first, the photoelectron spectra in graphite anddiamond were convoluted by a Gaussian function to simulate the amorphous state. Next, the convoluted
photoelectron spectra in graphite and diamond were summed, depending on the ratio of the sp2 and sp3
content. The simulated photoelectron spectra (thin lines) in glassy carbon and the three DLC films are shownin Fig. 1. In glassy carbon, the photoelectron spectrum is similar to the simulated one. It was found that thephotoelectron spectrum in glassy carbon is well reproduced using the simulated photoelectron spectra. In the52case of the three DLC films, the intensity of the peak at ~10.0 eV is larger while the intensity of the peak at~3.0 eV is smaller than the simulated photoelectron spectra. With increasing the sp3 content, the intensity ofthe peaks at ~10.0 and ~3.0 eV increased. Thus, except for the peaks at ~10.0 and ~3.0 eV, the photoelectron
spectra seem to be reproduced using the simulated photoelectron spectra.
Figure 2(a) shows the photoelectron spectra of the valence band region in the DLC film with accelerationenergy of the Ar cluster ions at 5 kV as a function of the excitation energy. The photoelectron spectrum at 70
eV is composed of a dominant feature between 12 and 0 eV and a small feature between 22 and 12 eV.
From the photon energy dependence, the feature between 22 and 12 eV is predominantly derived from the C
2s state, respectively. On the other hand, the feature between 12 and 0 eV is predominantly derived from theC 2p state. In a previous study on amorphous carbon [2], the total and partial density of states were
calculated by the MD method. The partial s and p density of states were distributed with peaks at ~18 and 8eV, respectively. In the previous study [2], the total density of states was also compared to the photoelectron
spectrum measured at 1486.6 eV. For the excitation energy, the intensity of the C 2s state was dominant.
Since the intensity of the C 2p state is relatively small, it is difficult to compare the photoelectron spectrum
and the density of states calculated by the MD method as for the C 2p state. At lower excitation energies, thecross section of the C 2p states is almost identical to that of the C 2s states. Therefore, at a lower excitationenergy, the photoelectron spectrum would be compared to the density of states with reasonable intensity as
for the C 2p states as well as the C 2s states. In Fig. 2(b), the photoelectron spectrum in the DLC film withacceleration energy of the Ar cluster ions of 5 kV was compared to the density of states (solid line) as
calculated by the MD method [2]. In the MD calculation, the sp3 content was 61 % while it was estimated to
be 51-57 % in the DLC film. Since the difference in the sp3 content is within 10 %, it is considered that there
is no significant variation for the comparison between the density of states calculated by the MD method andour photoelectron spectra. Partial s, p and p density of states (dotted line) are also plotted in Fig. 2(b). On
the whole, the photoelectron spectrum seems to be consistent with the density of states calculated by the MD
method. However, the position of the p state shifted to the higher binding energy side as compared to thephotoelectron spectrum. In addition, the intensity of the p state was larger compared to the photoelectron
spectrum. As discussed in the previous paper [2], the binding energy of the p state was overestimated in the
MD calculation. In addition, the p state was enhanced since the interlayer interaction was neglected [2]. If
these were modified, the density of states calculated by the MD method would be much more incorrespondence with the photoelectron spectrum.

|

|

|

Diamond

|

|

|

|

DLC 5 kV

|

|
|

|

|

DLC 7 kV

|

|
|

|
|
|

|

DLC 9 kV
|
|

|
|

h=
70 eV
138 eV216 eV1253.6 eV

(b)

|

|

DLC 5 kV

Intensity (arb. units)

Intensity (arb. units)||

Valence

Normal||(a)h = 70 eV

Valence||pGlassycarbonsp|Graphite20
100
Binding Energy (eV)Figure 2. (a) Photoelectron spectra (dots) of thevalence band region in the DLC film formed withacceleration energy of the Ar cluster ions at 5 kV
as a function of the excitation energy. (b)Photoelectron spectrum (dots) of the valence band
region in the DLC film formed with theacceleration energy of the Ar cluster ions at 5 kVand the total (solid line) and partial (dotted lines)
density of states calculated by the MD method.

20
10
0
Binding Energy (eV)Figure 1. Photoelectron spectra (dots) of thevalence band region in graphite, glassy carbon,
three DLC films, and diamond. In glassy carbon
and the three DLC films, simulated photoelectron
spectra (thin lines) are also shown. The spectra
were normalized by the maximum peak intensity.
References[1] Y. Haruyama et al., Jpn. J. Appl. Phys. 47, 3380 (2008).
[2] J. Schafer et al., Phys. Rev. B 53, 7762 (1996).

53

Characterization of Crystalline Structure of BN Thin Filmusing Soft X-ray Absorption Spectroscopy
Masahito Niibe1, Takuya Kotaka1, Satoko Hori2, and Shozo Inoue2
LASTI 1 & Graduate School of Eng., 2 University of Hyogo
Abstract
Crystalline structure of BN thin film prepared by magnetron sputtering technique wascharacterized using the soft X-ray absorption spectroscopy (XAS). Boron and nitrogen K-edge
X-ray absorption near edge structures (XANES) of the BN thin film were measured with total
electron yield (TEY) method and total fluorescence yield (TFY) method. The obtained spectra
indicate that the crystal structure of prepared BN film is very similar to that of cubic boron nitride(c-BN) powder. This study also suggests the effectiveness of XANES spectroscopy for evaluationof crystalline structure of BN thin films.
Introduction
As similar to carbon allotropic forms, boron nitride presents a polymorphism of hexagonal structure (h-BN)
having a hexagonal plane network, such as graphite, and cubic structure (c-BN) having a steric structure, such as
diamond. It is well known that h-BN is a relatively soft material. However, c-BN is known to be the second
hardest material after diamond, and preparation of c-BN thin film is extensively studied for a coating material
onto cutting tools. Moreover, it comes to the front of application to electronic and photo-electronic devices as
one of the wide-gap semiconductor materials.
In cases of BN thin film fabrication by sputtering or ion plating depositions, h-BN structure is preferentiallyformed because it is a stable phase at normal pressures. Stably-forming technology for c-BN structured thin film
was not confirmed as affairs. Characterization of crystalline structure of BN thin film is indispensable to confirm
the fabrication technology. However, application of X-ray diffraction method to the thin film characterization isvery difficult because the atomic scattering factors for these light elements (B and N) are very small.
On the other hand, X-ray absorption near edge structure (XANES) measurement is an appropriate techniqueto identify the crystal structure of BN thin film because the spectra of c-BN and h-BN are quite distinct and thebonding state on sp2 and sp3 can be observed in isolation. In this study, XANES spectroscopy at B-K and N-Kedge was carried out for the characterization of crystalline structure of BN thin film prepared by an RF
magnetron sputtering method.
Experiments
BN thin films were prepared on Si wafer (100) by the RF magnetron sputtering system. An h-BN disk (38 mm
in diameter) was used as target material. The substrate holder was electrically floated for applying a bias voltage
and could be heated up to 600 ℃ simultaneously. Ar+N2 mixed gas was used as working gas, and its pressure
was changed from 0.2 to 1.0 Pa. The DC bias was changed from -75 to 120 V in this study. Atomic compositionof the prepared sample was determined by an Auger electron spectroscopy (AES).
B-K and N-K XANES spectra of prepared samples were measured in the analyzing station of the beamline
BL9a at the NewSUBARU SR facility. The beamline monochromator was mounted with a plane varied-spacegrating with central groove density of 1200 l/mm, the energy resolution of which was about 0.2 eV at the photon
energy of 400 eV [1].
The measurement was conducted with a total electron yield (TEY) method with sample current mode and witha total fluorescence yield (TFY) method with measuring the amount of fluorescence by a photodiode. The TEY
and TFY measurements were carried out simultaneously for the same sample at the same position.
Self-absorption effects in TFY measurement were not corrected here for simplicity. It is well known that the
TEY method can yield information in a shallow region from the sample surface because of the small escapelength of photo-generated electrons of less than about 5nm [2]. Meanwhile, the TFY method can yield
information in a deeper region (bulk) of the sample of more than 100 nm because of the much longer penetration
depth of soft X-ray photons.
Results and discussion
Figures 1 and 2 show the B-K and N-K absorption spectra, respectively, of a prepared BN thin film together
with the spectra of the standard samples of h-BN and c-BN powder. The spectra of B-K and N-K absorption for
h-BN powder sample have sharp π* resonance peaks at 192 eV for B-K and at 401 eV for N-K edges,
respectively, which are caused from sp2 bonding states like a graphite. The π* resonance peaks have adependency of incident angle, which is originated from an orientation of hexagonal plane network of h-BN
structure. On the other hand, the spectra of B-K and N-K absorption for c-BN powder sample do not have a π*54resonance peaks and also do not have a dependency of incident angle.
In the spectra of the prepared sample as shown in Fig. 1 and 2, the π* resonance peaks in B-K or N-K edges
are almost not observed. These results indicate that the crystalline structure of the prepared BN film could bevery close to that of the c-BN crystal. The results also correspond well to the result of infrared absorption spectra
measured with FTIR spectrometer [3].
55Normalized ansorption [a.u.]

Normalized absorption [a.u.]6

Prepared BN thin film
43c-BN powder
21

4

Prepared BN thin film

3c-BN powder
2h-BN powder(60 deg.)1h-BN powder (60 deg.)
0

190

200

210

0
390

220

400

410

420

430

Photon energy [eV]Photon energy [eV]Fig. 2 N-K XANES spectra of a prepared BN thinfilm and standard h-BN and c-BN powders.

Fig. 1 B-K XANES spectra of a prepared BN thinfilm and standard h-BN and c-BN powders.

B-K XANES spectra (TEY) at angles of incidence of 90° and 45° for the prepared BN film with mixture ofc-BN and h-BN phases are shown in Fig. 3. Although the spectra for the h-BN rich mixture phase sample are notshown here, the π* resonance peak of the h-BN rich sample shows a small dependency of incident angle.
However, the angular dependency almost disappeared for the c-BN rich mixture phase sample as shown in Fig.
3.
Figure 4 shows the N-K XANES spectra (TEY and TFY) at angles of incidence of 90° and 45° for the
prepared BN film with mixture of c-BN and h-BN phases. The angular dependency of the π* resonance peak was
almost not observed as same as that of the B-K spectra in Fig. 3. Comparing the spectra obtained by TEY and
TFY method, the intensity of π* resonance peak at 401 eV in the TFY spectra is much higher than that in the
TEY spectra. This result indicates that the concentration ratio of h-BN phase could be relatively higher inside thethin film, though the ratio of c-BN could be much higher at the film surface.
The results obtained in this study suggests the effectiveness of X-ray absorption (XANES) spectroscopy forevaluation of crystalline structure of BN thin films.
BN film #114_N-K

BN film #114_B-K
10

8

Normalized absorption [a.u.]

Normalized absorption [a.u.]

12

6
TEY 45 deg.
4

TEY 90 deg.

2

0
185

190

195

200

205

210

215

10
8

TEY 45deg.

6

TEY 90deg.

4
2
0
390

220

Photon energy [eV]TFY 45deg.
TFY 90deg.

400

410

420

430

Photon energy [eV]Fig. 3 B-K XANES spectra of a prepared BN thinfilm with mixture phases of h-BN and c-BN.

Fig. 4 N-K XANES spectra of a prepared BN thinfilm with mixture phases of h-BN and c-BN.

References[1] M.Niibe et al., AIP Conf. Proc., 705, 576, (2004).
[2] J. Stohr, “NEXAFS Spectroscopy” Springer, Berlin (2003).
[3] S. Hori et al., Proc. ISSP2011, Kyoto, (2011) accepted.

55

Modification of Electronic States of Multi-walled Carbon
Nanotubes by Ion Irradiation
S. Honda1, S. Nanba1, Y. Hasegawa1, M. Niibe2, and M. Terasawa2
1
Univ. of Hyogo, 2LASTI Univ. of Hyogo
R. Hirase3, H. Yoshioka3, and H. Izumi3
3
Hyogo Pref. Inst. of Tech.
Abstract
Low energy Ar ions (0.5 - 2 keV) were irradiated to vertically aligned multi-walled carbon nanotube (MWCNT)
films. The structural properties and local bonding configurations of the irradiated vertically aligned MWCNT
films were characterized. It was found that the irradiation disrupted  and  bonds, and after the high ion dose,
MWCNT bundles were formed. This may be originated from bending of MWCNTs or welding between plural
MWCNTs under the ion irradiation.
Introduction
Irradiating carbon nanostructures withenergetic particles is thought to tailor the structure
and properties of the carbon nanostructures, andcan be applied to nanodevice fabrication. It wasreported that spatially localized Ar ion irradiationof individual MWCNTs deposited SiO2 substrates
was used for fabrication of quantum dots [1].
Moreover, Ar ion irradiation of MWCNTs
enhanced the field-emission properties due todefects induced by the ion irradiation [2]. In thisstudy, low energy Ar ions (0.5 - 2 keV) were
irradiated to vertically aligned MWCNT films,
and the structural properties and local bonding
configurations of the irradiated vertically aligned
MWCNT films by Raman spectroscopy and
X-ray absorption near-edge structure (XANES),
respectively. In addition, scanning electron
microscopy (SEM) and transmission electron
microscopy (TEM) were utilized to characterize
structural properties of the irradiated MWCNT
films.

areas, ID/IG, indicating disorder changes the natureof in-plane bonding of MWCNT sheets, deviating
away from intrinsic sp2 character [3,4]. The
XANES spectra of vertically aligned MWCNT
films irradiated with different energies of Ar ion
at a dose of 51015 cm-2, and vertically aligned
MWCNT films irradiated with a 1 keV Ar ion at
different doses are shown in Fig 2(a) and 2(b),respectively. In the spectrum for as-prepared
MWCNT films,  peak at 285 eV related tocarbon sp2 atoms and  peak at 292 eV related tocarbon sp2, sp3 atoms were clearly observed. On
the other hand, after the Ar ion irradiation, withincreasing the ion accelerated energy and dose,
both heights of  and  peaks are decreased, andwidth-broadening of  peak is recognized. The
XANES analysis supports the results from Raman
spectroscopy.

(a)Experiments and Results
Vertically aligned MWCNT films weresynthesized by catalytic chemical vapor
deposition (CCVD). Figure 1(a) and 1(b) show
SEM image of a vertically aligned MWCNT film
and its magnified image, respectively. Aligned
MWCNTs 160 m in length with radii ranging
between 20 and 40 nm were grown densely. An
ion gun (ULVAC-PHI, USG-3) is employed as theion source. Ar ions with energies ranging between
0.5 and 2 keV were irradiated to the MWCNT
films. The ion dose was varied between 11015
and 11017 cm-2. Micro-Raman spectra weretaken with Ar ion laser (514.5 nm) using a Raman
spectroscope (JASCO, NRS-2100). The carbon
K-edge XANES measurement was performed inbeam line BL9 at NewSUBARU.
Raman spectroscopy showed that Ar ion
irradiation changed the intensity ratio of
integrated D (1355 cm-1) and G peak (1580 cm-1)(b)

Fig.1. (a) SEM image of a vertically aligned
MWCNT film, and (b) its magnified image.

56

Figure 3(a) and 3(b) show SEM images of an
as-prepared vertically aligned MWCNT film, anda vertically aligned MWCNT film irradiated with
1 keV Ar ion at a dose of 51016 cm-2,
respectively. SEM observation revealed that
irradiation with the higher dose of 51016 cm-2 led
to self-organization in the MWCNT films that
tended to form bundles. This may be originatedfrom bending of MWCNTs or welding between
plural MWCNTs under the ion irradiation.

(a) 

(a)



(b)

As-prepared

1 keV
2 keV

(b) 

Fig.3. SEM images of (a) an as-preparedvertically aligned MWCNT film, and (b) avertically aligned MWCNT film irradiatedwith 1 keV Ar ion at a dose of 51016 cm-2.

As-prepared51015 cm-2
16

References[1] M. Suzuki et al., Appl. Phys. Lett. 81, 2273
(2002).
[2] D. -H. Kim et al., Chem. Phys. Lett. 378, 232(2003).
[3] F. Tuinstra and J. L. Koenig, J. Chem. Phys.
53, 1126 (1970).
[4] K. Niwase and T. Tanabe, Mater. Trans., JIM
34, 1111 (1993).

-2

510 cm

Fig.2. (a) XANES spectra of verticallyaligned MWCNT films irradiated withdifferent energies of Ar ion at a dose of
51015 cm-2, and (b) vertically aligned
MWCNT films irradiated with a 1 keV Ar
ion at different doses.

57Damage analysis of gallium nitride crystals etched by He
and Ar plasma
Takuya KOTAKA1, Masahito NIIBE1, Retsuo KAWAKAMI2, Takeshi INAOKA2,
Kikuo TOMINAGA2, and Takashi MUKAI3
1
Laboratory of Advanced Science and Technology for Industry, University of Hyogo
2
Institute of Socio-Techno Science Technology, The University of Tokushima, Japan
3
NICHIA Corporation, Japan
Abstract
Effect of etching damage on n-GaN crystal using a capacitively-coupled radio frequency
plasma with He and Ar gases was investigated. Local atomic structure of the etched surface was
evaluated by soft X-ray absorption spectroscopy (XAS) method. From N-K absorption spectra of
GaN surfaces etched by Ar plasma, disordered crystal structure was observed. From the spectra of
the surfaces etched by He plasma, the observed disarray of crystal structure was lower than that
etched by Ar plasma.
Introduction
GaN is expected to apply as semiconductor devices using under a harsh environment. Precise control of
etching by nanoprocess plasma is necessary to realize higher performance of the GaN semiconductor devices.
However, the reaction of nanoprocess plasma on the surface is so complicated that the understanding for precise
control is insufficient at the present [1]. To understand a mechanism of defect creation by physical etching,
Kawakami et al. have etched n-GaN crystal using a capacitively-coupled radio frequency (RF) plasma reactor
with rare gas of Ar and evaluated various characteristics [2,3].
In this work, to deepen the understanding of the control of etching plasma, n-GaN crystal surfaces were
etched by capacitively-coupled RF plasma reactor using He and Ar gases. Effect of etching damage on thesurface was analyzed by soft X-ray absorption spectroscopy (XAS). The results of etching damage by He and Ar
plasma are compared.
Experiment
GaN crystal was etched using a capacitively-coupled RF plasma reactor with unbalanced electrode structure[4] at the constant self-bias voltage of 200 V with changing gas pressure (10~100 mTorr) and treatment time
(5~200 min). Rare gases of He or Ar were used as plasma source gas. The sample was a Si-doped GaN with athickness of 2µm grown on sapphire substrates by Metal Organic Chemical Vapor Deposition (n-GaN, Nichia
Co.).
The XAS measurement was carried out at the BL-9A. N-K edge absorption spectra were obtained to analyze
the atomic local structure of the etched surfaces. The measurement was carried out with a total electron yield(TEY) method with sample current mode and with a total fluorescence yield (TFY) method with measuring theamount of fluorescence by a photodiode. An escape depth of electron by a photoelectric effect at the energy of
400 eV is less than about 5 nm [5]. Therefore, TEY method can analyze in a shallow region at the surface. TFY
method can analyze in a deep region from the surface (bulk), because the penetration depth of soft X-rays ismore than 100 nm. The photodiode was set at the angle of 30 deg. from the incidence light and lower left sightfrom the sample. The distance between the photodiode and the sample was about 20 mm. The used photodiodewas AXUV-100 (IRD Co.) with Al coating of 40 nm thick for avoiding the yellow band secondary emission.
Results and discussion
Figure 1 shows the N-K absorption spectra of n-GaN etched with He and Ar plasma at the treatment time of
200 min and normalized by peak intensities at the photon energy of 404 eV. Figs. 1(a), (b) and Figs. 1(c), (d) are
the spectra measured by TEY and TFY methods, respectively. Figs. 1(a) and (c) are the spectra of the surfaces
etched with He plasma. Figs. 1(b) and (d) are the spectra of the surfaces etched with Ar plasma.
The peak at photon energy of 400 to 412 eV shown in the as-grown sample has complicated shape.
According to the previous report by Katsikini et al. [6], those peaks are explained with superposition of six
Gaussian peaks named G1~G6.
Deenapanray et al. reported [7] that the N-K absorption spectra of GaN were changed by Ar ion
bombardment. In Fig. 1(b), the peak shapes (two shoulders at both sides of the sharp peak near 404 eV andothers) became smoother (dull) with increasing gas pressure from 10 to 100 mTorr. The change indicates that the58Normalized absorption [a.u.]

Normalized absorption [a.u.]

Normalized absorption [a.u.]

Normalized absorption [a.u.]

crystal structure of GaN was
disordered by Ar plasma etching. In
2.4
2.4
He TFYHe TEY(c)(a)
Fig. 1(a), the peak shapes (twoshoulders at both sides of the sharp
2
2
100mTorr
100mTorrpeak near 404 eV and others)
1.6
1.6
became a little smoother (dull) with
50mTorr
1.2
1.2
50mTorrincreasing gas pressure from 10 to
0.8
100 mTorr. The change indicates that
0.8
10mTorr
10mTorrthe crystal structure of GaN was
0.4
0.4
as-grown
disordered by He plasma etching. As
as-grown
00shown in Fig. 1(c) and (d), the peak390 395 400 405 410 415 420 425 430
390 395 400 405 410 415 420 425 430
shape in spectra measured by TFY
Photon energy [eV]Photon energy [eV]method was not changed. Therefore,
the disarray of crystal structure was
2.4
Ar TFY
2.4(b)
Ar TEY(d)occurred at shallow region in sample
22
surface.
100mTorr
100mTorr
1.6
1.6
Figure 2 shows the maximum
elastic energy transfer ratio of He
50mTorr
50mTorr
1.2
1.2
and Ar ion to atoms in various
0.8
0.8
10mTorr
nitride solid calculated with the PIS
10mTorr
0.4
0.4(Plasma behavior and its Interaction
as-grown
as-grownwith Surface reaction) particle
00model [4]. In Fig. 2, the elastic
390 395 400 405 410 415 420 425 430
390 395 400 405 410 415 420 425 430
energy transferred from He ion to N
Photon energy [eV]Photon energy [eV]and Ga atoms is less than the one
Figure 1 Normalized N-K absorption spectra of GaN crystal etched andfrom Ar ion. That is, the impact ofmeasured by (a): He plasma and TEY method, (b): Ar and TEY, (c):He ion on N and Ga atoms have a
He and TFY, (d): Ar and TFY, respectively, at the treatment time ofless influence on N and Ga atoms
200min.
than the one of Ar ion. In Fig. 1(a),the change in spectra of the surfaces
etched by He plasma was less pronounced
depending on gas pressure than the one etched by
Ar. Therefore, the disarray of crystal structure in
GaN etched by He plasma is lower than that etched
by Ar plasma.
Conclusions
The disordering of crystal was observed on the
GaN surfaces etched by Ar plasma, and it became
greater with increasing gas pressure. However, thedisarray of crystal structure on the surface etchedby He plasma was less pronounced. Comparing the
XAS spectra obtained by TEY and TFY method, it
was found that the changes in surface compositionand crystalline disordering were occurred only inthe shallow region from the n-GaN surface.

Figure 2 Maximum elastic energy transfer of He and Ar
References
ion to atoms in various nitride solid.
[1] S. J. Pearton, J. C. Zolper, R. J. Shul, and F. Ren,
J. Appl. Phys. 86 (1999) 1.
[2] R. Kawakami, T. Inaoka: Vacuum, 83 (2009) 490.
[3] R. Kawakami, T. Inaoka, K. Tominaga, and T. Mukai, Jpn. J. Appl. Phys. 48 (2009) 08HF01.
[4] R. Kawakami, T. Inaoka, K. Tominaga, A. Kuwahara, and T. Mukai, Jpn. J. Appl. Phys. 47 (2008) 6863.
[5] J. Stohr: “NEXAFS Spectroscopy”, Springer-Verlag, 1996.
[6] M. Katsikini, E. C. Paloura, and T.D. Moustakas, J. Appl. Phys. 83 (1998) 1437.
[7] P. N. K. Deenapanray, M. Petravic, K. –J. Kim, B. Kim, and G. Li, Appl. Phys. Lett. 83 (2003) 4948.

59

A Development Plan of Sputtering System
for Large Scale Telescope Mirror Coating
at Nishi-Harima Astronomical Observatory
Makoto Sakamoto1, Fumiaki Tsumuraya1 and Masahito Niibe2
Nish-harima Astronomical Observatory, University of Hyogo,407-2 Nishigaichi, Sayo-cho, Sayo-gun, Hyogo 679-5313, Japan
2
Laboratory of Advanced Science and Technology of Industry, University of Hyogo
3-1-2 Kouto.Kamigoori-cho, Ako-gun, Hyogo 678-1205, Japan
1

Abstract
The “Nayuta” astronomical telescope, having the largest mirror in Japan of 2 m diameter, isoperating at the Nishi-Harima Astronomical Observatory. To maintain the reflectivity of thetelescope mirrors, we are planning to develop a recoating system for large scale mirrors. The
system is necessary to meet the following requirements. 1: The coating quality satisfies thedemands in astronomical observation. 2: The coating can be carried out with mirror surface inupward direction. 3: The system is possible to pile up a protection coating. 4: silver metal canbe also coated instead of standard aluminum metal in the future. We selected a downward
sputtering as a coating system that enabled these requirements. In this paper, we report the
specification of the sputtering system and the preliminary experiment for extracting problem inthe coating of telescope mirrors.
1. Introduction
A large scale astronomical telescope, named “Nayuta”, has been
operated at the Nishi-Harima Astronomical Observatory in Hyogo
prefecture (Fig.1). The telescope is Cassegrain type constructingwith a 2m primary mirror and a 30 cm secondary mirror, and thescale is the largest within Japan. The mirrors used in the telescopemust be recoated at least in every five years, because of aging
deterioration and resulting decrease in reflectivity. However, there
is no appropriate coating system inside Japan in the present state ofaffairs. Therefore, we are planning to develop a recoating system
operating within the observatory facility for reductions of shipping
cost, risk of fatal damage to the mirrors and dead time of thetelescope operation.
Traditionally, coating of many telescope mirrors was conductedby vacuum evaporating deposition. However, because of the expectation of improving reflectivity andenvironmental durability, we chose a sputtering method for the coating. Sputtering method is also advantageous
for the risk of fatal damage because the method can easily deposit material to downward direction on a large scalemirror substrate keeping the surface with upward direction.
2．Coating material
A large part of electro-magnetic radiation from celestial
objects is reflected or absorbed by earth’s atmosphere. The
wavelength regions of the electric-magnetic radiation reachedto ground is limited as shown in Fig. 2. A lot of ground-based
optical telescope can observe these wavelengths in visible lightand a part of near-infrared (NIR) and ultraviolet (UV)radiations. The reflective coating must have enough reflectivity
in these observing wavelengths. Moreover, we must examine
protective coating because the environment of observation issimilar to that of out-door. The coated surface has to beguarded from dust and humidity.
2-1. Reflective coating
Aluminum coating has been used in a lot of telescope
mirrors because aluminum has good reflectivity from UV to
NIR region as shown in Fig. 2. However, the number ofobservatories having silver coated telescope was increasing,recently, because the CCD camera, the sensitivity of which israther low in the UV region, became a mainstream

60

Fig. 2 Spectral reflectivity of coatingobservation instrument. It is also because the infrared camera has been developed, which enable us to observe NIR
regions of J(1.2 μm), H(1.6 μm), and K(2.2 μm) bands.
In Nayuta telescope, the dominant observing wavelength is visible light using CCD camera and NIR radiation
using infrared camera. Therefore, we plan to provide the function of silver coating in a future.
2-2.Protection coating
The telescope is exposed to the open air during the observation. It was reported that the reflectivity of thetelescope mirror was deteriorated to the level of 60% even in a year [1] because of the high humidity in Japan.
A lot of telescopes specialized to academic studies are without protection coating. On the other hand, a numberof telescopes opened to the public, including Nayuta, have a protection coating. It will take one month or longer torecoat the mirror involving the work of removing from and installing to the Nayuta mirror cell. The working timecorresponds to above 10% of all the operation time. It is hard to keep the maintenance time of one month for every
year.
The suppression of the reflectivity deterioration can be expected by the additional protection coating. And it
will enable us to clean the dust of the mirror surface without fatal damages, too.
3．Quality of coating
Several factors have to be taken into account for the error of mirror accuracy, such as an accuracy of polishing,changing posture of telescope, and thermal deformation of both mirror and cell. The specification of Nayuta
telescope permits the error of mirror polishing within 0.07". The surface accuracy of mirror glass is less than 16.8nm(rms). The surface accuracy of coated mirror is less than 26.3 nm(rms). The surface roughness of the coating on
the mirror is under 2 nm(rms) [2]. In this experiment, target of the surface roughness of the coated mirror is 3% orless of the coating film thickness. Considering above, we estimate the thickness of coating film that will have an
enough reflectivity.
4．Basic specifications of the coating system
According to the consideration as mentioned above, the basic
specifications of the coating system are as follows,
1) The coating on the mirror surface is performed by adownward-sputtering method.
2) The size of mirror substrate is 2 m in diameter and 20 cm thickwith central hole of 50 cm in diameter.
3) The reflection coating material is aluminum or silver.
4) The roughness of coated surface is less than 2 nm(rms).
5) The protection coating is available. The material is SiO.
5．Preliminary experiment
To understand the details of the coating and removal of reflection
film on the mirror, we are carrying out a preliminary experiment withthe use of a small size vacuum evaporation system (ANELVA
EVD-500A) and the magnetron sputtering system (TOKUDA CFS-8EP).
We are optimizing the deposition condition for aluminum thin film. The
deposited thin films were evaluated with film thickness by stylus
profiler (Veeco Dektak2A) and with surface roughness by atomic force
microscope (Seiko Instruments Inc. NanoNavi , S-image). Fig. 3
shows the surface profile of aluminum thin films deposited by (a) EB
evaporation and (b) sputtering deposition. We are also examining aprotection coating using SiO.
Moreover, we are developing a spectral reflectometer for visible
light and near infra-red radiation using a fiber spectrometer (Ocean
Optics USB4000). The measuring method is relative reflectivity
comparing with aluminum reference mirror. Using the reflectometer, we
will evaluate not only the reflectivity of the coating but also the time
deterioration of the reflectivity. We are also examining the method of
removal of coated materials by wet chemical process and evaluating thedamage to the mirror glass surface. Finally, we are also examining thecost of coating system and its running cost.

(a)EB evaporation(b)Sputtering
Fig.3 Surface profile of aluminum
thin films.

[1]E.Watanabe,et.al: REPORT OF THE NATIONAL ASTRONOMICAL OBSERVERTORY OF JAPAN (1995)
Vol.2,No.3[2]Mitsubishi Electric Corporation: Detailed specification in production of large-scale telescope (2004)

61

Fabrication of Carbon Membrane X-ray Mask for Deep X-ray
Lithography Technique
Daiji Noda1, Atsushi Tokuoka1, Megumi Katori2, Yasuto Minamiyama2, and Tadashi Hattori1
1
Laboratory of Advanced Science and Technology for Industry, University of Hyogo,
2
Nanocreate Co., Ltd.
Abstract
For X-ray lithography, the accuracy of the fabricated structure depends largely on the accuracy of
the X-ray mask. Conventionally, a resin material is used for the support membrane for large area
X-ray masks. However, resin membranes have the disadvantage that they can sag after several
cycles of X-ray exposure due to the heat generated by the X-rays. For our new proposal we usedthin carbon wafers for the membrane material because carbon has an extremely small thermal
expansion coefficient. This new type of X-ray mask is very easy to process, and it is expected that
it will lead to more precise X-ray masks.
Introduction
X-ray imaging techniques have foundapplications in many fields such as medicine,
biology, inspection, material science, and so on.
However, clear X-ray images of samples with low
absorbance, such as biological soft tissue, are noteasy to obtain. To resolve this problem, several
methods which use X-ray phase information havebeen investigated [1]. In these methods, techniques
using X-ray gratings have been demonstrated [2]. Xray Talbot interferometry (XTI) [2] is one of thosetechniques used for X-ray phase imaging. In XTI two
X-ray gratings are used. However, the fabrication of
X-ray gratings is very challenging because athickness of 20 μm or more is required for use with
10-40 keV X-rays, even for gold which has a high Xray absorption coefficient.
X-ray lithography [3], which uses highly
directional synchrotron radiation, is one of thetechnologies that can be used for fabricating
micrometer sized structures. The X-ray mask patternis transferred onto the structure being fabricated dueto the difference between the X-ray transmittance inthe absorber and clear areas, and the precision withwhich the structure can be fabricated depends largelyon the precision of the X-ray mask. Since, in X-ray
lithography, the radiation is highly directional, amicro-fabrication technology that produces untapered
and high aspect ratio highly absorbent structures on a
low absorbent membrane is required.

layer on the carbon wafer, (b) applying resist over theseed layer to perform patterning by irradiation with
UV and development, (c) forming an X-ray absorber,
i.e. an Au film, by electrolytic plating, We succeededin making new X-ray mask with pitch pattern of 5.3
m and large effective area of 100  100 mm2, asshown in Fig. 2. In contrast to conventional silicon
substrates, the newly devised mask fabrication
process does not require further membrane
application, frame adhesion or substrate etching.
Thus, this is very simple process.

I. Seed layer deposition

II. Resist patterning

III. Au electroforming

Carbon

Ti

Au

SU-8

Fig. 1: New fabrication process of X-ray mask

Fabrication of carbon X-ray mask
The conventional resin membrane X-ray masks
have the disadvantage that, after several cycles of Xray exposure, they crease and sag due to X-rayderived heat. As a substitute for the conventional
resin membrane, we proposed to fabricate a new Xray mask using a carbon wafer membrane that has anextremely small thermal expansion coefficient and iseasy to process.
Figure 1 shows fabrication process using carbon
wafer for membrane material. The fabrication
process consists of three steps: (a) depositing a seed

Fig. 2: Picture of carbon X-ray mask

62with a large effective area of 100  100 mm2 on a 6
inch Si substrate, as shown in Fig. 5. This resultshows that new carbon X-ray mask give the best
performance.

Fabrication of X-ray grating
We used SU-8 photoresist for the X-ray
lithography. SU-8 was originally designed for UV
lithography, but it can also be used in deep X-ray
lithography to produce highly accurate, high aspectratio patterned structures. With the resin membrane
X-ray masks, we can fabricate photoresist structuresof about 30 μm in height with an X-ray exposure
dose of 4,000 mA·s/mm. The X-ray transmittance ofcarbon is less than that of resin, therefore, for masks
supported on carbon membranes, we varied the dosefrom 6,000 to 20,000 mA·s/mm and checked thephotoresist structures to determine the optimal
exposure dose. From the results, we concluded thatan X-ray exposure dose of approximately 12,000
mA·s/mm was optimal for fabricating structures with
1:1 line-to-space ratio patterns with a pitch of 5.3 μm[4]. Figure 3 shows a picture of an X-ray grating on a
4 inch Si substrate made using the new carbon X-ray
mask. The structure of the patterned photoresist over
the whole area is excellent. On the other hand, theresults obtained using the resin membrane X-ray
mask, shown in Fig. 4, show the photoresist structure
to be very poor. Pattern errors and sticking wereobserved from the bottom of the mask. These results
demonstrate the superior performance of the carbon
membrane-based X-ray masks.
We succeeded in fabricating an X-ray grating

Fig. 5: Picture of large area X-ray grating on 6
inch Si substrate.
Conclusions
We fabricated a new type of X-ray mask on both
4 inch and 6 inch carbon wafers. The carbon wafer
serves as the support membrane for the X-ray mask
and resolves the problem of thermal deformation
during X-ray exposure obtained when using maskswith resin membranes.
We successfully fabricated large area X-ray
masks on thin carbon wafers with patterns with apitch of 5.3 μm. The 200 μm thick carbon wafer was
sufficiently strong that further support around theedges of the membrane was unnecessary. Thus, thefabrication process is very easy compared to thatusing a resin support membrane which requires aframe bonded to the edges and etching to remove theSi substrate. The X-ray mask pattern formed on a 6
inch carbon wafer had a pitch of 5.3 μm and a heightof 4 μm covering a large effective area of 100  100
mm2. Using this new carbon X-ray mask, large area
X-ray gratings were fabricated on 6 inch Si substrates.

60 mm

Acknowledgment
This research was supported by the research
project “Development of Systems and Technology
for Advanced Measurement and Analysis” from theJapan Science and Technology Agency (JST).

Fig. 3: Picture of resist structure using newly
carbon X-ray mask.

References[1] A. Momose, Jpn. J. Appl. Phys., 44, 9A, pp.
6355-6367 (2005).
[2] A. Momose, W. Yashiro, T. Takeda, Y. Suzuki,
and T. Hattori, Jpn. J. Appl. Phys., 45, 6A, pp.
5254-5262, (2006).
[3] E. W. Becker, W. Ehrfeld, P. Hagmann, A. Maner,and D. Münchmeyer, Microelectron. Eng., 4, 1,
pp. 35-56, (1986).
[4] N. Takahashi, H. Tsujii, D. Noda, and T. Hattori,
Proc. 2008 IEEE Int. Symp. Micro-Nano Mech.
Human Sci. Nagoya, Japan, pp. 414-419 (2008).

60 mm

Fig. 4: Picture of resist structure using resin
membrane X-ray mask.

63

Fabrication of Au Structure Using Direct Electroplatingon Si Structures
Atsushi Tokuoka, Daiji Noda, and Tadashi Hattori
Laboratory of Advanced Science and Technology for Industry, University of Hyogo
Abstract
Good quality metallic structures can only be obtained by plating up from the bottoms of the etchedgrooves. Because it is difficult to form a seed layer just on the bottoms of the grooves, it is difficult
to fabricate metallic microstructures in high aspect ratio grooves etched using silicon dry etching
technology. To solve this problem, we developed a new fabrication method in which metallic
microstructures are fabricated by electroplating directly into grooves etched in the Si after the
sidewalls of the grooves have been coated with an insulating film. The depth of the grooves, andhence the thickness of the Au was 4 μm, and the pitch was 5.3 μm. Moreover, fabricating Au
microstructures in deeper higher aspect ratio grooves were also attempted. As a result, 20 μm deep
grooves were filled to a depth of 18 μm with Au. It is expected that this technology can be used in
the production of a wide variety of devices.
Introduction
Recently, the miniaturization and efficient ofmachine parts and electronic parts are advanced, andhighly precise microfabrication is requested formaking a variety of microstructure needed. An X-ray
lithography that uses the synchrotron radiation with ahigh directivity is paid to attention to make the highly
accurate and high aspect ratio microstructure.
Moreover, it is possible to make a metallic
microstructure of a high aspect ratio by making thestructure by X-ray lithography and the metal plating
if the substrate is made a conductor. However, theuse of the synchrotron radiation facilities where it
requires a high cost is indispensable to need thesynchrotron radiation with a high directivity for Xray lithography. Then, a new fabrication process thatthe synchrotron radiation facilities are not used andthe accuracy of the structure is not ruined isrequested. Even if making the microstructure of the
Si dry etching that uses Inductively Coupled Plasma
Reactive Ion Etching (ICP-RIE) doesn't use X rays,
the processing accuracy can make the microstructureof a high aspect ratio, as shown in Fig. 1.
It has been examined to make a metallic
microstructure of a high aspect ratio by using the Si
structure with the ICP-RIE in our laboratory. The
metal used Au that was able to be formed withplating [1]. It was necessary to form the metallic seedlayer only to the bottom of the groove of the
microstructure to form the Au structure in the grooveof the Si structure by the electroplating. If Au doesn't
extract it only from a bottom of the structures, thecave can be done in the structure, and an excellent Au
structure cannot be obtained as shown in Fig. 2.
However, the method of having a metallic seed only
to the bottom of the micro structure made by the Si
dry etching is difficult for having a complex process
and forming the microstructure to a large area andhigh aspect ratio.

5.3μm

Fig. 2: SEM image of defective Au structure.
Fabrication of proposal Au microstructure
The new method for fabricating Au structures bydirectly electroplating on a structured Si substrate isshown in Fig. 3. The fabrication process consists offive steps: (1) applying resist to the Si substrate andforming a mask pattern in it using UV lithography,(2) etching grooves into the silicon by Si dry etching
using an ICP etching system, (3) covering the Si
structure and the remaining resist with a polymer
film using the technique used in the Bosch process,(4) removing the polymer film from the bottoms ofthe grooves by vertical anisotropic etching (5)depositing Au in the grooves by electroplating up
from the bottoms of the grooves only. This new Au
microstructure fabrication method uses the polymer
coating process normally used in the Bosch process.

10μm

Fig. 1: SEM image of Si microstructures withaspect ratio of 7.

64

(1) UV lithography

5μm(2) Silicon dry etching

Fig. 4: SEM image of uniformity polymer layer
on Si microstructure.
(3) Piling up of polymer film

(4) Removing the polymer film

5μm(5) Electroplating

Fig. 5: SEM image of Au structures
Si substrate

Au

ResistPolymerConclusions
In the present study, metallic microstructures
were fabricated by filling with Au grooves etched insilicon by Si dry etching. The Au structures were
fabricated by electroplating directly on the Si.
However, good quality Au microstructures cannot be
obtained by electroplating in etched grooves since
growth takes place from both the bottoms and thesidewalls of the grooves. This can be achieved bycoating the sidewalls with polymer, such as that usedin the Bosch process used for Si dry etching. A 0.2
μm thick polymer film was found to be sufficiently
insulating, so a film of about this thickness was
deposited on the sidewalls of the etched grooves,which were then filled with Au by directly
electroplating on the Si. As a result, Au structures 4
μm deep without voids were made. In addition, wewere able to fabricate these Au structure over an areaof 60 mm squares.

Fig. 3: Fabrication process of new Au
microstructures.
It is necessary that growth takes place from thebottoms of the grooves only in order to form goodquality Au structures. The polymer coating forms aninsulating layer that prevents electroplating on the
sidewalls.
Fabrication of Au structure
In our first attempts to deposit polymer films on
Si microstructures, there was a tendency for thepolymer to accumulate near the bottom of the groove,
resulting in a thick layer at the bottom. This led totwo problems. First, in addition to Au forming at thebottom of the groove, it was also formed near the top
where the polymer was thin. Secondly, the thickpolymer layer had an effect on the shape of theelectroplated Au microstructure. Further attempts
produced polymer films with much more uniform
thickness as shown in Fig. 4. With these more
uniform coatings, we were able to fabricate highquality Au structures by electroplating as shown in
Fig. 5. As the figure shows, Au formed byelectroplating completely fills the 4 μm deep grooves
etched in the substrate. However, to achieve a given
width for the Au microstructure it is necessary to take
into consideration both the width of the grooves in
the Si structure and the thickness of polymer
deposited on the sides. Nevertheless, these results
reinforced our expectation that it is possible tofabricate much higher Au structures in more deeply
etched Si.

Acknowledgment
This research was supported by the research
project “Development of Systems and Technology
for Advanced Measurement and Analysis” from theJapan Science and Technology Agency (JST).
References[1] H. Tsujii, K. Shimada, M. Tanaka, D. Noda, and T.
Hattori, J. Advanced Mech. Design, Systems,
Manuf., 2, 2, pp. 246-251 (2008).
[2] F. Lamer, A. Schilp, K. Funk, and M. Offenberg,
Tech. Digest MEMS ’99, pp.211-216 (1999).

65

Fabrication of High Performance Light Guide Plate
Takaya Fujimoto1, Kenji Yamashita2, Satoshi Nishida2, Daiji Noda1, and Tadashi Hattori1
1
Laboratory of Advanced Science and Technology for Industry, University of Hyogo,
2
Nanocreate Co., Ltd.
Abstract
Recently, LED (Light Emitting Diode) is paid to attention as a new source of light. However, it
doesn't turn to shine on a wide area efficiently because LED is a point light. Then, the method of
the light guide plate technology used for the liquid crystal display etc, and use as the LED lighting
is examined. In the process of study, it has been understood that luminance increases by increasing
the number of dots. Therefore, an accumulating method of piling up two or more light guide plates
was proposed as a method of achieving high luminance for highly effective lighting usage, and thedevice was analyzed with an optical simulator. As a result of optimization, the average luminancehas improved by 15 %.
Introduction
In recent years, the LED has received attention asa light source for a new form of lighting, taking theplace of lighting forms such as fluorescent lamps [1].
Recently, LEDs with the luminous efficacy equal tothat of a fluorescent lamp have been developed.
Generally, the fluorescent lamp and the incandescentlamp are enumerated as forms of lighting. However,as for the advantages of using LEDs as a lighting
source, low power consumption, high durability, andlong life are enumerated. The power consumption of
an LED is about half that of a fluorescent lamp; thelongevity about five times as much. A considerable
reduction in power consumption and the amount ofwaste generated can be expected through thereplacement of the currently used incandescent andfluorescent lamp lighting with LED lighting.
However, LED is not suitable for efficiently
illuminating a wide area, because LED is a point
light source. Products have been made using amethod of arranging a large quantity of LEDs toshine over a wide area. However, irregularity inlighting due to their respective positions on theluminescence side, and there is the problem of highcost due to the large numbers LEDs required.
Therefore, it was decided to convert LED point
luminescence into plane emission form by using lightguide plate technology, to increase the LED’s
efficiency and solve the above problems. Thismethod of LED lighting used is examined here.
Figure 1 shows a schematic diagram of a light guideplate.

taper corner is 70 degree, referring to past research
results [2]. The light guide plate converts the point
light source to plane emission. One advantage of thelight guide plate is its efficient use of light throughthe conversion of point light sources to planeemission. To achieve uniform plane emission, an
important factor is bumps on the light guide plate that
release light from the diffuser surface. Uniform planeemission is achieved by rendering an optimal bumpshape and allocation pattern.
Light Guide

Li ht
Reflector Sheet

LED

Dot

A cross section

Fig. 1: Explanation chart of light guide plate.
Piling method
A high luminance LED and a light guide plate
were combined to create a brighter lighting panel, foruse as a lighting device. However, the size of thehigh luminance LEDs on the luminescence side was
5 mm, and there were no a light guide plates
available of appropriate thickness. Therefore, we
considered either two light guide plates of board
thickness 2.6 mm or five light guide plates of board
thickness 1 mm, piled up, to be suitable for the
luminescence side. The result of increasing thenumber of piled sheets was to raise the mean
luminance obtained. The reasons were thought to be
the dots arranged by piling up two or more lightguide plates besides the light guide plate bottom, andthe ability to increase the number of dots even in alight guide plate of the same thickness. This was
because of the higher probability that light would hit
the dots, as shown in Fig. 2. Therefore, a pilingHigh performance light guide plate
In the light guide plate, light is guided from an
LED or other light source to desired locations via
total internal reflection rendered by an index ofrefraction differential between the air and the diffusermaterial. The light in light guide plate tears a totalreflection condition by reflecting in an internal
projection (dot) and irradiates the surface. The shapeof the dots was assumed to be frustum of circularcone shape, that the diameter on was 10 µm, thediameter below was 52 µm, height was 30 µm, and66

Light guide plate

LED

Reflector
Piled light guide plate

Fig. 2: Ray route outline chats of each lightguide plate.

cd/m²(a) usual
method of piling up two or more light guide plates
was proposed as a method of achieving highluminance for highly effective lighting usage, and thedevice was analyzed with an optical simulator.
First of all, a small light guide plate (30 × 30mm2) was used. The dot arrangement area, thenumber of sheets piled up, and the total board
thickness of the light guide plates was changed andthe results were analyzed. An air layer of 0.01 mm
was inserted between each light guide plate. The lightsource on the luminescence side used one white LED
whose size matched each total board thickness. The
measuring method emitted white light of 1 W fromthe LED, and measured the total energy of the lightemitted from the luminescence side of the light guideplate. Figure 3 shows the result for a total board
thickness of 2 mm.
The total light output energy changed according
to the number of piled sheets and the total number ofdots on the light guide plate. This result could also be
confirmed for other total board thicknesses. Although
in some cases the light output energy became
saturated, the total light output energy increased as aresult of any increases in the number of piled sheets
and the total number of dots.
A piled light guide plate of the same condition
was designed and verified according to a light guideplate (luminescence area = 50 × 90 mm2, board
thickness = 1 mm) that had been designed and madeby a previous research for the sake of comparison.
Figure 4 shows simulation results of usual type andpiled type. Average luminance is 767 cd/m2 in the668
94

Conclusions
The method of improving the utilization
efficiency of light further to apply the light guideplate made in this laboratory as a form of lighting,and achieving high luminance, were examined. The
light guide plates were piled up as a method ofraising the utilization efficiency of light and themethod of achieving high luminance by the piling
method to increase the total of number of dots was
proposed. The piling method was verified by using
the simulation. Near a practical size as the lighting
because a light guide plate so far at the time of
optimized it in the past was compared with the piled
light guide plate based on the above-mentioned result,and optimization of the arrangement of the dots ofthe piled light guide plate of luminescence area 50 ×
90 mm2 and the total board thickness 1 mm wasachieved. As a result of optimization, the averageluminance of the piled light guide plates was 767
cd/m2, while that of previous light guide plates was
668 cd/m2, representing an improvement of about
15 %.
It will be possible to convert it to a higher
luminance light guide plate even when the same
source of light is used.

The total light energy output (W/m²)

0.4
0.3
9 x 9 (mm²)
12.7 x 12.7 (mm²)
18 x 18 (mm²)
22 x 22 (mm²)

References[1] H. C. Chien and Z. P. Chen, Microsyst. Technol.
15, pp. 383-389 (2009).
[2] Y. Okayama, K. Yamashita, D. Noda, and T.
Hattori, Proc. 2008 IEEE Int. Symp. Micro-Nano
Mech. Human Sci., pp. 408-413 (2008)00

150,000

300,000

450,000

767
95

piled light guide plate, compared to an averageluminance of 668 cd/m2 in a past light guide plate;hence the average luminance improved by about
15 %. Moreover, the dot total is 480,779 pieces in the
piled light guiding plate while the dot total is 191,008
pieces in the previous light guide plate. The numberof dots is about 2.5 times the previous figure. The
number of sheets of accumulating was decided andoptimized so that the number might become one
million that was the number of saturation dots.

0.5

0.1

average luminance (cd/m2)
illumination uniformity (%)

Fig. 4: Luminance distribution on surface ofeach light guide plate (simulation).

0.6

0.2

(b) three pieces piled

600,000

T he total number of dots (pieces)

Fig. 3: The relationship between the total lightenergy output and the total number of
dots.

67

Technique for Preparing Defect-free High Aspect Ratio SU-8
Resist Structure Using X-ray Lithography
1V. K. Singh, S. Maekawa1, M. Katori2, Y. Minamiyama2, D. Noda3, and T. Hattori3
Natioal Institute of Information and Communications Technology, 2Nanocreate Co., Ltd.,
3
Laboratory of Advanced Science and Technology for Industry, University of Hyogo

Abstract
This paper describes the process of deep X-ray lithography (DXRL) using epoxy negative
photoresist SU-8. Resist coating, soft bake, exposure, post exposure bake, and development of theresist are characterized. We have successfully fabricated HAR and defect-free vertical channel
structures of 100 and 200 μm depths with 10 μm width in SU-8 resist introducing a new vapor
development technique that will be useful for various MEMS devices. Utilizing this technique, we
can not only increase the exposure dose for thicker resist structure without worrying the over dose
effect but also reduce the developing time significantly.
Introduction
This paper describes the process of deep X-ray
lithography (DXRL) using epoxy negative
photoresist SU-8. Resist coating, soft bake, exposure,post exposure bake, and development of the resist arecharacterized. The negative resist SU-8 has been
increasingly used in micro- and nanotechnologies
due to its excellent coating, planarization andprocessing properties as well as its mechanical andchemical stability. The fabrication of polymer based
high aspect ratio (HAR) micro-pillar structures by Xray lithography is investigated. A low-energy beamline of 1.0 GeV with carbon X-ray mask is used tocreate arrayed micro-pillars on soda glass. One of the
major limitations in the use of SU-8 in lithographic
processes is the occurrence of internal stress andhence the distortion of the microstructure. In thisstudy, a technique for preparing the defect-free HAR
SU-8 resist structure is described.

dose, and PEB temperature and time are considered
to have an influence on stress developed in resist
structure [2]. The complex balance of parameters
decides the quality of the resist structure.
Results and discussions
Figure 1 shows the optical micrographs of resist
pattern exposed at different doses. It is shown that as
exposure dose value increases, resist residue on top
surface of the pattern increases due to the higher
internal stress. The typical thicknesses of bumps on
pattern edge and cross-shaped pattern edge are 1.5
and 0.5 μm, respectively. This result suggest that
limitations of exposure dose value for SU-8 resistthat means thicker resist where higher dose is neededcannot be fabricated successfully.
Figure 2 shows the effect of PEB temperature on
the resist pattern. The exposure dose used is 25,000
mA·s/mm for 200 μm thick SU-8 resist. Figure 2(a)shows a photograph of cross- shaped pattern after Xray exposure and before PEB. The temperatureduring X-ray exposure is assumed 30 ºC. Figure 2(b)shows a photograph after PEB at 65 ºC for 1 min. it
can be seen that unexposed resist start to come out
from the channel due to the expansion of exposed
resists. It further becomes worse when PEB is carriedout at 95 ºC for 1 min to enhance the cross-linking of
the exposed resist as shown in Fig. 2(c). However,
the recommended PEB process is 5 to 10 min at 95ºC from the technical data sheet to complete theExperimental
The resist used for the process is SU-8 3050. The
resist height is approximately 200 μm, achieved bytwice spin coating. The samples are soft baked at 95ºC for 1 to 12 hours to remove the solvent [1]. The
X-ray exposure doses used are from 10,000 to 25,000
mA·s/mm. The Post exposure bake (PEB) is carriedout at 95 ºC for 1 to 10 min. The substrates aredeveloped using pure PGMEA with gentle ultrasonicagitation. The parameters of Soft bake time, exposure(a) 25,000 mA·s/mm(b) 20,000 mA·s/mm(c) 15,000 mA·s/mm

Fig. 1: Top view of fabricated pillar array. The exposure doses are changed. Resist residue can be seen
surrounding the cross-shaped design in a decreasing manner.

68

(a)

(b)

(c)

Fig. 2: Optical photographs of (a) X-ray exposed sample, (b) after PEB at 65 °C for 1 min, and (c) further
at 95 °C for 1 min. Resist residue increases with PEB temperature and time.
cross-linking. It means longer PEB cannot be applied
to avoid the resist residue problem.
A technique that can be applied without any
limitation and with no side effects is attractive. For
removing resist residue developed during DXRL on
the resist structure, the post exposure baked sample isplaced in a caped beaker with the liquid developer,
PGMEA at room temperature for 15 min as shown in
Fig. 3. The resist is considered to diffuse from thickregion to thin region and spread surrounding surface
due to surface tension effect. Figure 4(a) shows top
SEM view of the pillars structure. The residue ofresist can be seen clearly. The coefficient of thermal
expansion (CTE) of SU-8 is 52 ppm/ºC [3]. It has
been noticed that unexposed SU-8 might be squeezed
out of a channel due to the thermal expansion of the
exposed region, resulting in a resist residue on the
top surface. The problem caused by thermal
expansion becomes more serious when the exposedarea is bigger. In our case, pillars are square of 150 ×
150 μm2 arranged with 10 μm gap. The effect causedby the large internal stress can be alleviated either byreducing the exposed area or by generating a discrete
small-sized exposed region [4]. But this idea also
limits the area of fabrication design and structure.
Figure 4(b) shows top SEM photograph of resist
structure after PGMEA vapor treatment. By putting
the X-ray exposed sample in the caped beaker with
PGMEA after PEB, the photoresist flows on thesample and becomes enough soft to remove during
standard developing. This technique smoothen theresist surface too.

(a) normal condition(b) after vapor treatment
Fig. 4: SEM image of SU-8 resist pattern by Xray lithography. Top views of resist
pattern (a) suffering from resist residue
problem, (b) becomes defect-free after
applying PGMEA vapor treatment.

Conclusions
We have successfully fabricated HAR and defect-

free vertical channel structures of 100 and 200 μm
depths with 10 μm width in SU-8 resist introducing a
new vapor development technique that will be usefulfor various MEMS devices. More detail investigationon the fabricated micro structures are still underresearches. Utilizing this technique, we can not only
increase the exposure dose for thicker resist structure
without worrying the over dose effect but also reducethe developing time significantly.

Fig. 3: Setup for putting the sample in the
PGMEA vapor environment.

References[1] L. Singleton, M. Kufner, and S. Megtert, J.
Photopolym. Sci. Technol., 14, pp. 649-656(2001).
[2] R. L. Barber, M. K. Ghantasala, R. Divan, K. D.
Vora, E. C. Harvey, and D. C. Mancini,
Microsyst. Technol., 11, pp. 303-310 (2005).
[3] H. Lorenz, M. Laudon, and P. Renaud,
Microelectron. Eng., 41-42, pp. 371–374 (1998).
[4] C. H. Lin, G. B. Lee, B. W. Chang, and G. L.
Chang, J.Micromech. Microeng, 12, pp. 590-597(2002).

69

70

LIST OF PUBLICATIONS

List of publications(1) Papers
1. S.Amano, K.Masuda, A.Shimoura, S.Miyamoto, T.Mochizuki“Characterization of a laser-plasma extreme-ultraviolet source using a rotating cryogenic Xe target”
Applied Physics B, Vol.101, pp.213-219(2010).
2. S.Amano, K.Masuda, S.Miyamoto, T.Mochizuki“Soft X-ray source by laser produced Xe plasma” (inJapanese)
IEEJ Trans. EIS, Vol.130, No.10, 1768(2010).
3. P.E.Nica, M.Agop, S.Miyamoto S.Amano, A.Nagano, T.Inoue, E.Poll, T.Mochizuki“Multi-peak structure of the ion current in laser produced plasma”
European Physical Journal D 60, pp.317-323(2010).
4. N.Matsuo, N.Isoda, A.Heya, S. Amano, S.Miyamoto, T. Mochizuki, N.Kawamoto“Influence of Laser Plasma Soft X-Ray Irradiation on Crystallization of a-Si Film by Infrared Furnace
Annealing”
Materials Transactions, Vol. 51, pp.1490-1493 (2010).
5. S.Amano, K.Horikawa, S.Miyamoto, T.Mochizuki,"Laser-Compton gamma-ray source at a beamline (BL01) in NewSUBARU "AIP Conference Proceedings (SRI2009), Vol.1234, pp.495-498 (2010).
6. K.Horikawa, S.Miyamoto, S.Amano, T. Mochizuki,“Measurements for the energy and flux of laser Compton scattering g-ray photons generated in anelectron storage ring: NewSUBARU”
Nucl. Instrum. and Methods A, Vol.618, pp.209-215(2010).
7. K.Horikawa, S.Miyamoto, S.Amano, D.Li, K.Imasaki T. Mochizuki,“Quantum beam generation by laser Compton scattering gamma-ray” (in Japanese)
IEEJ Trans.EIS, Vol.130, No.10, 1784(2010).
8. T. Shima, Y. Nagai, S. Miyamoto, S. Amano, K. Horikawa, T. Mochizuki, H. Utsunomiya, and H. Akimune"Experimental Study of Nuclear Astrophysics with Photon Beams"
AIP Conf. Proc. May 12, 2010 - Volume 1235, pp. 315-321, Issue Date: 12 May (2010).
9. T. Shima, Y. Nagai, S. Miyamoto, S. Amano, K. Horikawa, T. Mochizuki, H. Utsunomiya, and H. Akimune"Study of 12C(γ,2α)4He with NewSUBARU laser Compton scattered gamma-ray beam"
AIP Conf. Proc. August 12, 2010 - Volume 1269, pp. 469-471, Issue Date: 12 August (2010).
10. Yoshihiko Shoji"Generating coherent THz radiation in electron storage rings using an ac sextupole magnet and a verticalkicker magnet"
Phys. Rev. ST Accel. Beams 13, 060702 (2010).
11. Yoshihiko Shoji"Design of a Multi-Element Corrector Magnet for the Storage Ring NewSUBARU"
IEEE Transactions on Applied Superconductivity, Vol.20, No.3, pp.230-233 (2010).
12. Yuichi Utsumi, Shigeaki Yamamoto, Tomoyuki Kuroki, and Masaaki Okubo"Direct bonding of PFTF sheets assisted by shynchrotron radiation induced surface modification”
Microsystem Technologies, 16, 8-9, pp.1495-1500 (2010).
13. Yoshiaki Ukita, Saki Kondo, Chiwa Kataoka, Masahiro Takeo, Seiji Negoro, and Yuichi Utsumi,“Immunoassay using poly-tetrafluoroethylene microstructure in organic solvent”
ibid., pp.1465-1470 , (2010).

7114. Tsunemasa Saiki, Katsuhide Okada and Yuichi Utsumi"Micro liquid rotor operated by surface-acoustic-wave"
ibid., pp. 1589-1594 , (2010).
15. Saki Kondo, Tsukasa Azeta, Yoshiaki Ukita, Yuichi Utsumi,"Vertical Liquid Transportation Through Capillary Bundle Structure Using Centrifugal Force"
ibid., pp. 1577-1580 (2010).
16. Akinobu Yamaguchi, Keiichi Motoi, Hideki Miyajima, Tsuyoshi Uchiyama, and Yuichi Utsumi"Detection of Nonlinear Spin Dynamics in Artifial magnets Using Rectifiction of Planar Hall Effect"
Journal of the Magnetics Society of Japan , 34, pp. 73-77 (2010).
17. Tsuyoshi Uchiyama, Akinobu Yamaguchi, and Yuichi Utsumi"Noise Characterization of Coil Detection Type Magnetic Field Sensor Utilizing Pulse Excitation
Amorphous Wire Magneto-Impeadance Element"
ibid., pp.533-536 (2010).
18. Tomoya Omukai, Atsushi Kinoshita, Fusao Komada, and Yuichi Utsumi"High density cell culture using 3D scaffold with capillary bundle structure" (in Japanese)
IEEJ Transactions on Electronics, Information and Systems, 130, 10, pp.1789-1794(2010).
19. Saki Kondo, Tsukasa Azeta, Yoshiaki Ukita, Chiwa Kataoka, and Yuichi Utsumi"Immunoassay System Using Three-dimensional Micro Fluid Network" (in Japanese)
ibid., pp.1844-1816, (2010).
20. Takao Fukuoka, Daisuke Fukuoka, Yasushige Mori, and Yuichi Utsumi"Development of Multi-Analytes DNA Microchip by Using 3-D Nanoprototyping Fabrication Method" (inJapanese)
ibid., pp.1806-1810(2010).
21 Tsunemasa Saiki, Katsuhide Okada, and Yuichi Utsumi"Highly Efficient Liquid Flow Actuator Operated by Surface Acoustic Waves" (in Japanese)
ibid., pp. 1717-1722(2010).
22. Yoshiaki Ukita, Saki Kondo, Masahiro Takeo, Seiji Negoro, Chiwa Kataoka, Yuichi Utsumi"Vertical Microreactor Stack Consist of poly-(tetrafluoroethylene) Microfluidics for Immunoassay" (inJapanese)
ibid., pp. 1756-1761(2010).
23. Atsushi Kinoshita, Tomoya Omukai, Fusao Komada, and Yuichi Utsumi“High density cell culture using micro 3D structure"
Journal of Japan Institute of Electronics packaging, 13, 3, 200-203(2010).
24. Shigeaki Yamamoto, Yoshiaki Ukita, Kozo Mochiji, Yuichi Utsumi"Microfabrication of Poly (tetrafluoroethylene) Using SR Direct Etching"
Accepted for publication on 20th, Sep, 2010, Electrical Engineering in Japan, (2010).
25. Tsunamasa Saiki, Katsuhide Okada, Yuichi Utsumi“Fabrication and Estimation of Novel Micro Liquid Rotor that Operates with Surface-Acoustic-Wave”
Accepted for publication on 20th, Sep, 2010, Electrical Engineering in Japan, (2010).
26. Yuichi Utsumi"Proposal of 3D Micro prototyping Using Synchrotron Radiation and Its Application to BioMicrosystems" (Invited)
Service Robotics and Mechatronics (Springer), 7-14, (2010).
27. Daiju Shiono, Hideo Hada, Kazufumi Sato, Yasuyuki Fukushima, Takeo Watanabe, and Hiroo Kinoshita"Fundamental Decomposition Analysis of Chemically Amplified Molecular Resist for below 22 nm
Resolution"
J. Photopolymer Sci. Technol 23, pp.649-656 (2010).

72

28. Y. Fukushima, Y. Yamaguchi, T. Kimura, T. Iguchi, T. Harada, T. Watanabe, and H. Kinoshita"EUV interference lithography for 22 nm node and below"
ibid., pp.673-680 (2010).
29. Y. Yamaguchi, Y. Fukushima, T. Iguchi, H. Kinoshita, T. Harada, and T. Watanabe"Fabrication process of EUV-IL transmission grating"ibid., pp.681-686 (2010).
30. Y. Fukushima, N. Sakagami, T. Kimura, Y. Kamaji, T. Iguchi, Y. Yamaguchi, M. Tada, T. Harada, T.
Watanabe, and H. Kinoshita"Development of Extreme Ultraviolet Interference Lithography System"
Jpn. J. Appl. Phys. 49, 06GD06 (2010).
31. Y. Fukushima, N. Sakagami, T. Kimura, Y. Kamaji, T. Iguchi, Y. Yamaguchi, M. Tada, T. Harada, T.
Watanabe, and H. Kinoshita"Development of Extreme Ulytaviolet Interference Lithography System"
ibid., 06GD06-1, 06GD06-5 (2010).
32. Daiju Shiono, Hideo Hada, Kazufumi Sato, Yasuyuki Fukushima, Takeo Watanabe, and Hiroo Kinoshita"Decomposition and Roughness Analysis of Chemically Amplified Molecular Resist for Reducing LWR"
ibid., 06GF05-1, 06GF05-5 (2010).
33. K. Takase, Y. Kamaji, N. Sakagami, T. Iguchi, M. Tada, Y. Yamaguchi, Y. Fukushima, T. Harada, T.
Watanabe, and H. Kinoshita"Imaging Performance Improvement of an Extreme Ultraviolet Microscope"ibid., 06GD07-1, 06GD07-4 (2010).
34. T. Kaito, H. Oba, Y. Sugiyama, A. Yasaka, J. Fujita, T. Suzuki, K. Kanda, and S. Matsui"Deposition Yield and Physical Property of Carbon Films Deposited by Focused Ion Beam Chemical
Vapor Deposition"
ibid., 06GH08 (2010).
35. K. Kanda, M. Okada, Y. Kang, M. Niibe, A. Wada, H. Ito, T. Suzuki, and S. Matsui"Structural Changes in Diamond-Like Carbon Films Fabricated by Ga Focused-Ion-Beam-Assisted
Deposition Caused by Annealing"ibid., 06GH06 (2010).
36. Y. Nakai, Y.i Kang, M. Okada, Y. Haruyama, K. Kanda, T. Ichihashi, and S. Matsui"Mechanical Characteristics of Nanosprings Fabricated by Focused-Ion-Beam Chemical Vapor
Deposition Using Ferrocene Source Gas"
ibid., 06GH07 (2010).
37. Makoto Okada, Takahiro Nakayama, Yuji Kang, Yuichi Haruyama, Kazuhiro Kanda, and Shinji Matsui.
"Direct Patterning on Sol-Gel Low-k Porous Silica by Thermal Nanoimprinting"ibid., 06GL08 (2010).
38. Yuji Kang, Makoto Okada, Chiaki Minari, Kazuhiro Kanda, Yuichi Haruyama, and Shinji Matsui.
"Room-Temperature Nanoimprinting Using Liquid-Phase Hydrogen Silsesquioxane with Hard
Poly(dimethylsiloxane) Mold"
ibid., 06GL13 (2010).
39. Makoto Okada, Mayuko Shibata, Yuichi Haruyama, Kazuhiro Kanda, Yoshihiko Hirai, and Shinji Matsui"Cross-sectional observation of nanoimprint resins filled in SiO2/Si mold pattern using scanning electron
microscopy"
Microelectronic Engineering, 87, 1159 (2010).
40. M. Tagawa, K. Yokota, A. Kitamura, K. Matsumoto, A. Yoshigoe, Y. Teraoka, K. Kanda, M. Niibe"Synchrotron Radiation Photoelectron Spectroscopy and Near-Edge X-Ray Absorption Fine Structure
Study on Oxidative Etching of Diamond Like Carbon Films by Hyperthermal Atomic Oxygen"73

Applied Surface Science 2567, pp.678-7683 (2010)
41. Makoto Okada, Takafumi Kishiro, Kaori Yanagihara, Masashi Ataka, Norimichi Anazawa, and Shinji
Matsui''Newly developed electron beam stepper for nanoimprint mold fabrication''
J. Vac. Sci. Technol B 28 , pp. 740-743(2010).
42. Makoto Okada, Masatoshi Maeda, Satoshi Shimatani, Shoji Otaka, and Shinji Matsui''Fabrication of Replica Mold by Room Temperature Nanoimprinting using Organic Spin-on-glass''
J. Photopolym. Sci. Tech. 23, pp.65-68 (2010).
43. Makoto Okada, Takafumi Kishiro, Kaori Yanagihara, Masashi Ataka, Norimichi Anazawa, and Shinji
Matsui''Large Area Nanoimprint Mold Fabricated by Electron Beam Stepper''ibid., pp. 75-78 (2010).
44. Yuji Kang, Makoto Okada, Yuichi Haruyama, Kazuhiro Kanda, and Shinji Matsui“UV irradiation Effect on Pattern Size Shrinkage of Sol-gel Indium Tin Oxide Replicated by Nanoimprint
Lithography”
ibid., pp.39-43, (2010).
45. Yasuki Nakai, Shinya Omoto, Yong Kang, Makoto Okada, Kazuhiro Kanda, Yuichi Haruyama, and Shinji
Matsui"Evaluation of Heat Durability of Fluorinated Antisticking Layers"ibid., 23, pp55-58, (2010).
46. Shinya Omoto, Makoto Okada, Yuji Kang, Kazuhiro Kanda, Yuichi Haruyama, Seiji Tono and Shinji Matsui"Comparison of EB Exposure Characteristics between HSQ and Calix Arene of High Resolution Negative
Resist"ibid., pp. 97-100, (2010).
47. Y. Haruyama, S. Matsui, T. Ideta and H. Ishigaki“Annealing Effect on the Chemical Composition of a Synchrotron Radiation Irradiation” (in Japanese)
IEEJ Transactions on Electoronics, Information and Systems, Vol. 130-C, pp. 1741-1745, (2010).
47. R. Kawakami, M. Niibe, T. Fukudome, A. Takeichi, T. Inaoka, and K. Tominaga:“Effect of DBD Air Plasma Treatment on TiO2 Thin Film Surfaces”
Jpn, J. Appl. Phys., 50 01BE02 pp. 1-5 (2011).
49. R. Kawakami, T. Inaoka, K. Tominaga, M. Niibe, T. Mukai, A. Takeichi, and T. Fukudome:“Synergy Effect of Xenon Plasma Ions and Ultraviolet Lights on GaN Etch Surface Damage andModification”
Trans. Materials Res. Soc. Japan, 36, 75-78 (2011).
50. M. Niibe, K. Koida, Y. Kakutani:”Inhibition of carbon growth and removal of carbon deposits on extreme ultraviolet lithography mirrors
by extreme ultraviolet irradiation in the presence of water, oxygen, or oxygen/ozone mixtures”
J. Vac. Sci. Technol. B 29 011030-1~5 (2011).
51. M. Niibe, Y. Maeda, R. Kawakami, T. Inaoka, K. Tominaga, and T. Mukai:”Surface analysis on n-GaN crystal damaged by RF-plasma-etching with Ar, Kr, and Xe gases”
Physica Status Solidi, C 8, 435-437 (2011).
52. R. Kawakami, T. Inaoka, K. Tominaga, M. Niibe T. Mukai, A. Takeichi, and T. Fukudome:”Etch-induced damage characteristics of n-GaN surfaces by capacitively coupled radio frequency He andAr plasmas”
Physica Status Solidi, C 8, 441-443 (2011).
53. Masahito Niibe, Kazuyoshi Miyamoto, Tohru Mitamura, K. Mochiji:“Identification of B-K NEXAFS peaks of boron nitride thin film prepared by sputtering deposition”

74

J. Vac. Sci. Technol. A 28, 1157~1160 (2010).
54. Naoki Takahashi, Hiroshi Tujii, Megumi Katori, Kenji Yamashita, Daiji Noda, Tadashi Hattori“Fabrication of X-rays mask with carbon membrane for diffraction gratings”
Microsystem Technologies, Vol. 16, No. 8-9, pp. 1303-1307 (2010).
55. Daiji Noda, Hiroshi Tsuji, Naoki Takahashi, Tadashi Hattori“Fabrication of Precision X-ray Mask for X-ray Grating of X-ray Talbot Interferometer”
Microsystem Technologies, Vol. 16, No. 8-9, pp. 1309-1313 (2010).
56. Yoshitaka Sawa, Kenji Yamashita, Takeshi Kitadani, Daiji Noda, Tadashi Hattori“Fabrication of High Hardness Micro Metal Mold using double layer by Nickel Electroforming and Ni-B
Electroless Alloy Plating”
Microsystem Technologies, Vol. 16, No. 8-9, pp. 1369-1375 (2010).
57. Hiroaki Miyake, Kazufumi Nishimoto, Satoshi Nishida, Daiji Noda, Tadashi Hattori“Fabrication of Micro Capacitive Inclination Sensor by Resin Molding”
Microsystem Technologies, Vol. 16, No. 8-9, pp. 1431-1437,(2010).
58. Daiji Noda, Masaru Setomoto, Yuki Kobayashi, Tadashi Hattori“Fabrication of Microcoils with Narrow and High Aspect Ratio Coil Lines”
Microsystem Technologies, Vol. 16, No. 8-9, pp. 1479-1483 (2010).
59. Yuta Okayama, Kenji Yamashita, Yoshitake Sawa, Daiji Noda, Tadashi Hattori“Fabrication of Ultraviolet range Light Guide Plate”
Microsystem Technologies, Vol. 16, No. 8-9, pp. 1625-1631 (2010).
60. Tadashi Hattori“Fabrication of a High Functional Light Guide Plate Replicated by Micro Ni Mold and It’s Application
for LED Lights”
Journal of The Surface Finishing Society of Japan, Vol. 61, No. 9, pp. 630-636 (2010).
61. Daiji Noda, Tadashi Hattori“Fabrication of Microcoils with Narrow and High Aspect Ratio Coil Lines”
The International Journal of the Robotics Society of Japan, Advanced Robotics Vol. 24, No. 10, pp. 14611470 (2010).
62. Daiji Noda, Atsushi Tokuoka, Tadashi Hattori“Fabrication of Au Microstructure Using ICP-RIE”
Transaction of The Japan Society of Mechanical Engineers series C, Vol. 77, No. 775, pp. 691-697 (2011).

75

(2) International Meetings
1. S.Amano, T.Inoue, T.Harada“Grazing-incidence EUV collector coated by DLC”,
2010 International Synchrotron on Extreme Ultraviolet Lithography, Kobe, Oct.17-20 (2010).
2. S.Hashimoto, S.Miyamoto, K.Kawata, T.Shinomoto, Y.Minagawa"Improved stability of the radiation intensity at the NewSUBARU synchrotron radiation facility"
Proceedings of International Particle Accelerator Conference (2010).
3. Y. Ukita, T. Azeta, S. Kondo, C. Kataoka, S. Yusa, M. Takeo,Y. Takamura, and Y. Utsumi“High-Sensitive Detection of Polychlorinated Biphenyl on Three-dimensional LAB-ON-A-CD”
The 14th International Conference on Miniaturized Systems for Chemistry and Life Science (µTAS2010),
pp345-347, Groningen, Netherland, October 3-7 (2010)
4. Y. Ukita, T. Azeta, S. Kondo, C. Kataoka, S. Yusa, M. Takeo,Y. Takamura, and Y. Utsumi“High-Sensitive Enzyme-linked immunosorbent assay in Three-dimensional LAB-ON-A-CD”
ibid. pp1475-14777.
5. Tsukasa Azeta, Yoshiaki Ukita, Yoshito Hirose, Saki Kondo and Yuichi Utsumi,“Three-dimensional Microfluidics Device Using Centrifugal Force”
Digest of Papers, 2010 International Microprocess and Nanotechnology Conference (MNC2010), 12D-11107, Kokura, Japan, November 9-12, (2010)
6. Mitsuhiro Yoshida, Yoshito Hirose, Yoshiaki Ukita, Kunihiko Mabuchi Yuichi Utsumi,“Proposal of stacked electrodes for multiplex neural interface”
ibid.
7. Tsukasa Azeta, Yoshiaki Ukita, Yoshito Hirose, Saki Kondo and Yuichi Utsumi,“High-Sensitive Enzyme-linked immunosorbent assay in Three-dimensional LAB-ON-A-CD”
ibid.
8. Y. Ukita, T. Azeta, S. Kondo, C. Kataoka, S. Yusa, M. Takeo, and Y. Utsumi“Three-dimensional Centrifugal Microfluidics for Environmenatal Analysis”
ibid.
9. Takao Fukuoka, Yasushige Mori, and Yuichi Utsumi“The anisotropic assembles of Au nanoparticles for near Infrared surface-enhanced Raman scattering”
The 2010 International Chemical Congress of Pacific Basin Societies (Pacifichem 2010) (Honolulu, USA),
Symposium of Plasmonics and Nanophotonics for Chemical Sensing, Imaging and Spectroscopy, 165,
Dec.15, (2010).
10. Takao Fukuoka, Daisuke Fukuoka, Yoshiaki Ukita, Yuji Kang, Shinji Matsui, and Yuichi Utsumi“Gold nanoparticles assembled nanovalley for microfluidic SERS Detection”
ibid., 455, Dec. 16, (2010).
11. Takao Fukuoka, Daisuke Fukuoka, Yoshiaki Ukita, Yuji Kang, Shinji Matsui, and Yuichi Utsumi“Fabrication of gold nanoparticles assembled nanovalley for surface enhanced Raman scattering”
ibid., 681, Dec. 17, (2010).
12. Takao Fukuoka, Yuichi Utsumi, and Yasushige Mori
“New strategy of non-labeling ligand-receptor binding assay in aqueous medium using anisotropic
aggregation of Au nanoparticles”
ibid., 1362, Dec. 19, (2010).
13. Yoshiaki Ukita, Chiwa Kataoka, Masahiro Takeo, Seiji Negoro, Yuzuru Takamura, Yuichi Utsum“Detection of polychlorinatedbiphenyl by using antibody-bound fluoroplastic capillary bundle structure”
The 2010 International Chemical Congress of Pacific Basin Societies (Pacifichem 2010) (Honolulu, USA),
Symposium of Microfluidic and Nanofluidic Devices for Chemical and Biochemical Experimentation,
549,USA, Dec. 17, (2010).

7614. Takeshi Komoto,Tsunemasa Saiki,Yuichi Utsumi“Application of Surfacwe Acoustic Wave Actuator to Lab-on-a-chip”
The first Japan-China-Korea Joint Seminar on MEMS/NEMS 2010 For Green & Life Innovetion,
P6,Sapporo Convention Center,Hokkaido,Japan, August 30-31 (2010).
15. Tsukasa Azeta,Yoshiaki Ukita,Yoshito Hirose,Saki Kondo,Yuichi Utsumi“Three-dimensional Micro Fludics Device Using Centrifugal Force”
ibid.
16. Mitsuhiro Yoshida, Yoshito Hirose, Yoshiaki Ukita, Kunihiko Mabuchi, Yuichi Utsumi“Proposal of stacked electrodes for multiplex neural interface”
ibid.
17. Hiroo Kinoshita and Takeo Watanabe"A New Resist Evaluation System developed at NewSUBARU"
2010 International Workshop on EUV Lithography, Maui, Hawaii, USA, Jul. 21-25, (2010).
18. Hiroo Kinoshita, Kei Takase, Toshiyuki Uno, Takeo Watanabe, and Tetuo Harada"Study of the Minimum Phase Defect Affecting the Exposure Result"ibid.
19. Yasuyuki Fukushima, Yuya Yamaguchi, Teruhiko Kimura, Takafumi Iguchi, Tetsuo Harada, Takeo
Watanabe, and Hiroo Kinoshita"EUV interference lithography for 22 nm node and below"
The 27th International Conference of Photopolymer Science and Technology, Chiba, Japan,
June 22- July 25, (2010).
20. Yuya Yamaguchi, Yakusyuki Fukushima, Takafumi Iguchi, Hiroo Kinoshita, Tetsuo Harada, and Takeo
Watanabe"Fabrication process of EUV-IL transmission grating"ibid.
21. Daiju Shiono, Hideo Hada, Kazufumi Sato, Yasuyuki Fukushima, Takeo Watanabe, Hiroo Kinoshita"Fundamental Decomposition Analysis of Chemically Amplified Molecular Resist for below 22 nm
Resolution"ibid.
22. Takeo Watanabe, Naohiro Matsuda, Tetsuo Harada, Hiroo Kinoshita, Hiroaki Oizumi, and Toshiro Itani"In-situ Contamination Thickness Measurement by Novel Resist Evaluation System at NewSUBARU"
22th Microprocesses and Nanotechnology Conference, Kokura, Fukuoka, Japan, Nov.9-12, (2010).
23. Tetsuo Harada, Masato Nakasuji, Masaki Tada, Takeo Watanabe, Hiroo Kinoshita"Critical Dimension Evaluation of an EUV Mask utilizing the Coherent EUV Scatterometry Microscope"ibid.
24. Yuya Yamaguchi, Yasuyuki Fukushima, Masaki Tada, Tetsuo Harada, Takeo Watanabe, and Hiroo
Kinoshita"Fabrication of transmission grating for replication of 20 nm node resist pattern"
ibid.
25. Kazuhiro Kanda, Masahito Niibe, Akira Wada, Haruhiko Itoh, Tsuneo Suzuki, and Hidetoshi Saitoh"Near-Edge X-ray Absorption Fine Structure Spectra of Si-containing DLC Thin Films"
4th Workshop for International Standardization of Diamond-like Carbon Coatings [P6]26. Akira Wada, Takeshi Ogaki, Tomoyuki Yasukawa, Fumio Mizutani, Masahito Tagawa, Tsuneo Suzuki,
Masahito Niibe, Hidetoshi Saitoh, Kazuhiro Kanda, and Haruhiko Ito"Near edge X-ray absorption fine structure measurements of DLC and a-SiCx:H films"
ibid. [P7]7727. A. Wada, T. Suzuki, M. Niibe, H. Ito and K. Kanda"Annealing Effect of W incorporated DLC fabricated by Ga focused ion beam CVD"
23rd International Microprocesses and Nanotechnology Conference (MNC2010) [11D-8-134L]
28. S. Omoto, M. Okada, Y. Kang, Y. Nakai, K. Kanda, Y. Haruyama, S. Tono and S. Matsui"High-resolution UV Nanoimprint Mold fabricated by EB Lithography using Calix Arene"
ibid. [11D-8-94]
29. Y. Sawada, M. Okada, H. Miyake, T. Ohsaki, Y. Hirai, Y. Haruyama, K. Kanda and S. Matsui"Characteristics of Synthesized Radicaland Cationic-UV Nanoimprint Resins"ibid. [11D-8-95]
30. Y. Kang, S. Omoto, M. Okada, K. Kanda, Y. Haruyama and S. Matsui"Wafer Scale Room-Temperature Nanoimprint using Spin-Coated HSQ with PDMS Mold"
ibid. [11D-8-96]
31. D. Yamashita, M. Okada, Y. Kang, Y. Haruyama, K. Kanda and S. Matsui"Evaluation of Si Containing UV Nanoimprint Resin and Bilayer Structure Application"
ibid. [11D-8-138L]
32. Y. Nakai, Y. Kang, M. Okada, Y. Haruyama, K. Kanda and S. Matsui"Annealing Effect of Fe-Ga doped DLC Film formed by Focused-ion-beam Chemical Vapor Deposition
using Ferrocene Source Gas"
ibid. [12D-11-56]
33. Y. Kang, M. Okada, K. Kanda, Y. Haruyama and S. Matsui"Fabrication and Characterization of SiOx Moth-eye Structure by Room-temperature Nanoimprint using
HSQ"
ibid. [12D-11-87]
34. M. Okada, M. Iwasa, Y. Haruyama, K. Kanda, H. Hiroshima and S. Matsui"Adhesion Force Measurement by Scanning Probe Microscopy under Pentafluoropropane Gas
Atmosphere"
ibid. [12D-11-97]
35. M. Okada, M. Iwasa, Y. Haruyama, K. Kanda, K. Kuramoto, M. Nakagawa and S. Matsui"In-situ Measurement of Adhesion Force between Fluorinated Self-assembled Monolayer and UV
Nanoimprint Resin by scanning Probe Microscopy"
ibid. [12D-11-100]
36. Shinji Matsui, Hiroshi Hiroshima, Yoshihiko Hirai, and Masaru Nakagawa''Research and Development on Process Science and CD Control in High-Throughput UV Nanoimprint''
ibid.
37. Makoto Okada, Masayuki Iwasa, Yuichi Haruyama, Kazuhiro Kanda, Kei Kuramoto, Masaru Nakagawa, andShinji Matsui"Evaluation Of Interaction Between Antisticking Layer And UV Curable Resin By Scanning Probe
Microscopy"
The 9th International Conference on Nanoimprint and Nanoprint Technology (NNT2010) [P25]38. Yuji Kang, Makoto Okada, Kazuhiro Kanda, Yuichi Haruyama, and Shinji Matsui,"Fabrication And Characterization Of Siox Moth-Eye Structure By Room-Temperature Nanoimprint
Using Caged- And Ladder-HSQ"
ibid. [P26]39. Makoto Okada, Mizuho Kondo, Kazuhiro Kanda, Yuichi Haruyama, Nobuhiro Kawatsuki, Shinji Matsui"Evaluation of imprinting characteristics for photoinduced liquid crystalline polymer"
The 36th International Conference on Micro & Nano Engineering (MNE2010) [O-LITH-04]
40. Makoto Okada, Takafumi Kishiro, Masashi Ataka, Norimichi Anazawa, and Shinji Matsui

78

''Seamless long line and space pattern fabrication for nanoimprint mold by using electron beam stepper''ibid. (2010).
41. Makoto Okada, Shinichi Nakano, Koji Yamashita, Shinichiro Kawahara, and Shinji Matsui"Direct patterning on side chain crystalline polymer by thermal nanoimprinting using mold without
antisticking layer"
ibid. (2010).
42. S. Omoto, M. Okada, Y. Kang, K.Kanda, Y. Haruyama, S. Tono, and S. Matsui"Fabrication of High-Resolution Nanoimprint Mold by Electron Beam Lithography Using Calix Arene"
The 3rd Asian Symposium on Nano Imprint Lithography (ASNIL 2010) [1P-1]
43. Y. Kang, M. Okada, K. Kanda, Y. Haruyama and S. Matsui"Fabrication and Characterization of SiOx Moth-Eye Structure by Room-Temperature Nanoimprint with
Liquid-Phase HSQ and PDMS Replica Mold"
ibid. [1P-9]
44. Y. Nakai, S. Omoto, Y. Kang, M. Okada, K. Kanda, Y. Haruyama and S. Matsui"Durability of Self-Assemble Monolayers Against Heat in Nanoimprinting"ibid. [1P-13]
45. M. Chinen, M. Okada, Y. Haruyama, K. Kanda, H. Hiroshima and S. Matsui"Examination of Pentafluoropropane Gas Effect for UV Nanoimprint Resin in Macro-Scale Area"ibid. [1P-14]
46. M. Chinen, M. Okada, M. Iyo, S. Tachibana, Y. Haruyama, K. Kanda and S. Matsui"UV Nanoimprinting on Calixarene Derivative"
ibid. [1P-16]
47. Y. Sawada, M. Okada, H. Miyake, T. Ohsaki, Y. Hirai , Y. Haruyama, K. Kanda and S. Matsui"Evaluation of Radical- and Cationic- UV-Curable Resins for Studying UV-Nanoimprint"
ibid. [2A-6]
48. D. Yamashita, M. Okada, Y. Kang, Y. Haruyama , K. Kanda and S. Matsui"Bilayer Resist Method Using Si Containing Photoresist in UV Nanoimprint Lithography"
ibid. [22A-15]
49. M. Chinen, M. Okada, Y. Haruyama, K. Kanda, H. Hiroshima, and S. Matsui“Examination of pentafluoropropane gas effect for UV nanoimprint resin in macro-scale area”
ibid.
50. M. Okada, M. Maeda, S. Shimatani, S. Otaka, and S. Matsui''Organic Spin on Glass Replica Mold Fabricated by Room Temperature Nanoimprinting''
ibid.
51. Shinya Omoto, Makoto Okada, Yuji Kang, Yasuki Nakai, Kazuhiro Kanda, Yuichi Haruyama, Shinji Matsui,"New Method of EB Exposure Stability using HSQ High-Resolution Negative Resist"
The 54th International Conference on Erectron, Ion, and Photon Beam Technology and Nanofabrication(EIPBN'10) [P2-1]
52. Yasuki Nakai, Yuji Kang, Makoto Okada, Yuichi Haruyama, Kazuhiro Kanda, Shinji Matusi,"Evaluating Mechanical Characteristics of Various Shape Nanosprings Fabricated by Focused-ion-beam
Chemical Vapor Deposition"
ibid. [P5-3]
53. Makoto Okada, Katsuhiko Tone, Meisyo Kiko, Tetsuya Katase*, Yuichi Haruyama, Kazuhiro Kanda, Shinji
Matsui,"Durability Evaluation of Antisticking Layer by Step and Repeat UV Nanoimprinting"ibid. [P12-4]

7954. Makoto Okada, Masayuki Iwasa*, Hiroto Miyake, Nobuji Sakai, Yuichi Haruyama, Kazuhiro Kanda, Shinji
Matsui"Adhesion Force Evaluation of UV-Curable Nanoimprint Resins by Scanning Probe Microscopy with UV
Irradiation System"
ibid. [P12-8]
55. Yuji Kang, Shinya Omoto, Yasuki Nakai, Makoto Okada, Kazuhiro Kanda, Yuichi Haruyama, Shinji Matsui"Nanoimprint Replication of Three-Dimensional Structure Fabricated by FIB-CVD"
ibid. [9A.5]
56. Akira Wada, Tomoyuki Yasukawa, Fumio Mizutani, Masahito Niibe, Tsuneo Suzuki, Hidetoshi Saitoh,Hatuhiko Ito, Kazuhiro Kanda"Effect of O2 Plasma Etching on DLC Films"
4th International Conference on New Diamond and Nano Carbons(NDNC2010) [P146]
57. Hidetoshi Saitoh, Masanori Hiratsuka, Kenji Hirakuri, Kazuhiro Kanda, Makoto Kano, Masanori Tsujioka,
Hideki Nakamori, Naoto Ohtake, Naoji Fujimori"Current Status of DLC Films Classification in Japan"
ibid. [P151]
58. Kazuhiro Kanda, Kumiko Yokota, Masahito Tagawa, Mayumi Tode, Yuden Teraoka, Shinji Matsui"Radiation Effect of the Soft X-ray on the Highly-Hydrogenated Diamond-Like Carbon Film"
ibid. [P157]
59. Akira Wada, Takeshi Ohgaki, Masahito Niibe, Masahito Tagawa, Hidetoshi Saitoh, Kazuhiro Kanda,
Hatuhiko Ito,
"Local Structural Analysis of a-SiCx:H Films Formed by Decomposition of Tetramethylsialane in
Microwave discharge flow of Ar"
ibid. [P412]
60. Shinji Matsui, Hiroshi Hiroshima, Yoshihiko Hirai, and Masaru Nakagawa''Research and Development on Process Science and CD Control in High-Throughput UV Nanoimprint''
ibid.
61. K. Kanda, K. Yokota, M. Tagawa, M. Tode, Y. Teraoka, S. Matsui"Departure Process of Hydrogen from Highly-Hydrogenated Diamond-Like Carbon Film by Exposure to
Synchrotron Radiation"
5th JAEA Synchrotron Radiation Research Symposium Material Science on Metal Hydride [P-03].
62. M. Okada, M. Maeda, S. Shimatani, S. Otaka, and S. Matsui''Fabrication of Replica Mold by Room Temperature Nanoimprinting using Organic Spin-on-glass''
International Conference of Photopolymer Science and Technology, Chiba, 2010/6/24.
63. M. Okada, T. Kishiro, K. Yanagihara, M. Ataka, N. Anazawa, and S. Matsui''Large Area Nanoimprint Mold Fabricated by Electron Beam Stepper''ibid.
64. Y. Kang, M. Okada, Y. Haruyama, K. Kanda, and S. Matsui“UV irradiation Effect on Pattern Size Shrinkage of Sol-gel Indium Tin Oxide Replicated by Nanoimprint
Lithography”
ibid.
65. Y. Nakai, S. Omoto, Y. Kang, M. Okada, K. Kanda, Y. Haruyama, and S. Matsui"Evaluation of Heat Durability of Fluorinated Antisticking Layers"ibid.
66. S. Omoto, M. Okada, Y. Kang, K. Kanda, Y. Haruyama, S. Tono and S. Matsui"Comparison of EB Exposure Characteristics between HSQ and Calix Arene of High Resolution Negative
Resist"ibid.

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67. M. Okada, M. Iwasa, Y. Haruyama, K. Kanda, K. Kuramoto, M. Nakagawa, and S. Matsui''Evaluation of interaction between antisticking layer and UV curable resin by scanning probe
microscopy''
9th International Conference on Nanoimprint and Nanoprint Technology 2010, Copenhagen, Denmark(2010).
68. M. Okada, S. Nakano, K. Yamashita, S. Kawahara, and S. Matsui''Characteristics Evaluation of Side Chain Crystalline Polymer for Nanoimprinting''
ibid. (2010).
69. Y. Kang, M. Okada, Y. Haruyama, K. Kanda, and S. Matsui"Fabrication and characterization of SiOx moth-eye structure by room-temperature nanoimprint using
caged- and ladder-HSQ"
ibid. (2010).
70. Shinji Matsui''Research and Development on Process Science and CD Control in High-Throughput UV Nanoimprint''
2010 International Symposium on Lithography Extensions, Kobe, Oct. 22 (2010).
71. Shinji Matsui"Research and Development on High-Throughput UV Nanoimprint"
Jeju Island, Korea, 2010/11/22.
72. Y. Haruyama, Y. Kang, M. Okada, and S. Matsui"Electronic structure of the fluorinated diamond-like carbon thin films as a function of annealing
temperature using photoelectron spectroscopy"
The 37th International Conference on Vacuum Ultraviolet and X-ray Physics (VUVX2010), July, 3P008,
Vancouver, Canada
73. M. Niibe, T. Kotaka, R. Kawakami, T. Inaoka, K. Tominaga, and T. Mukai:”Damage Analysis of Plasma-etched n-GaN Crystal Surface by Nitrogen K-edge NEXAFS Spectroscopy”
3ed Int’l. Symposium on Advanced Plasma Sci. and its Applications, Nagoya, Japan 6-9 March (2011).
74.M. Niibe, K. Koida, T. Nakayama, S. Terashima, A. Miyake, H. Kubo, Y. Kakutani, S. Matsunari, T. Aoki, S.
Kawata”Nonlinear Behavior of Carbon Deposition on the Projection Optics Mirrors by EUV Irradiation in the
Coexistence of Hydrocarbon Gas and Water Vapor”
23ed Int’l. Microprocesses and Nanotechnology Conference, 9-12 Nov. 2010 Kokura, Japan.
75. M. Niibe, K. Koida, Y. Kakutani, S. Matsunari, T. Aoki, S. Kawata, T. Nakayama, S. Terashima, A. Miyake,
H. Kubo”Contamination experiment for EUVL optics mirrors with the use of single bunch SR”
2010 Int’l Symp. Extreme Ultraviolet Lithography, 17-20 Oct. Kobe, Japan.
76.M. Niibe, K. Koida, Y. Kakutani, T. Nakayama, S. Terashima, A. Miyake, H. Kubo, S. Matsunari, T. Aoki, S.
Kawata”Non-linearity of carbon deposition by EUV irradiation in the coexistence of hydrocarbon gas and water
vapor”
2010 Int’l Symp. Extreme Ultraviolet Lithography, 17-20 Oct. Kobe, Japan.
77. M. Niibe, Y. Maeda, R. Kawakami, T. Inaoka, K. Tominaga, and T. Mukai:”Surface analysis on n-GaN crystal damaged by RF-plasma-etching with Ar, Kr, and Xe gases”
37th Int’l. Symposium on Compound Semiconductors, Takamatsu Japan, May 31-June 4 (2010).
78. R. Kawakami, T. Inaoka, K. Tominaga, M. Niibe T. Mukai, A. Takeichi, and T. Fukudome:”Etch-induced damage characteristics of n-GaN surfaces by capacitively coupled radio frequency He andAr plasmas”
37th Int’l. Symposium on Compound Semiconductors, Takamatsu Japan, May 31-June 4 (2010).

8179. Atsushi Tokuoka, Naoki Takahashi, Daiji Noda and Tadashi Hattori“Fabrication of Au structure using direct electroplating on Si structure”
2010 IEEE International Symposium on Micro-Nano Mechatronics and Human Science (MHS 2010),
Nagoya, Japan, November 7-10, 2010
90. Daiji Noda, Naoki Takahashi, Atsushi Tokuoka, Megumi Katori, Tadashi Hattori“Fabrication of carbon membrane X-ray mask for X-ray Lithography”
ASME 2010 International Mechanical Engineering Congress & Exposition (IMECE 2010), Vancouver,
Canada, November 12-18, 2010
91. Daiji Noda, Masaru Setomoto, Tadashi Hattori“Fabrication of High Aspect Ratio Microcoils Using X-ray Lithography”
ASME 2010 International Mechanical Engineering Congress & Exposition (IMECE 2010), Vancouver,
Canada, November 12-18, 2010
92. Takaya Fujimoto, Kenji Yamashita, Satoshi Nishida, Daiji Noda, Tadashi Hattori“Fabrication of High Performance Light Guide Plate and New Design for High Luminance”
ASME 2010 International Mechanical Engineering Congress & Exposition (IMECE 2010), Vancouver,
Canada, November 12-18, 2010
93. Daiji Noda, Naoki Takahashi, Megumi Katori, Tadashi Hattori“Fabrication of New X-ray Mask Using carbon Wafer membrane”
2010 International Chemical Congress of pacific Basin Societies (PACIFICHEM 2010), Honolulu, USA,
December 15-20, 2010
94. Vijay Kumar Singh, Satoshi Maekawa, Megumi Katori, Yasuto Minamiyama, Daiji Noda, Tadashi Hattori,“Technique for Preparing Defect-free High Aspect Ratio SU-8 Resist Structure Using X-ray Lithography”
2011 6th International Conference on Nano/Micro Engineering and Molecular Systems (NEMS 2011),
Kaohsiung, Taiwan, February 20-23, 201182

(3) Award
1. Hiroo Kinoshita
The Japan Society of Applied Physics Fellow Award"The pioneer of the EUV Lithography"

2. Hiroo Kinoshita
The 10th (2010) Yamazaki-Teiichi Prize"Semiconductor & Semiconductor Device"
3. Yuji Kang, Makoto Okada, Yuichi Haruyama, Kazuhiro Kanda, and Shinji Matsui
The 2nd prize in the NNT 2010 Gold Sponsor AwardInternational Conference on Nanoimprint and Nanoprint Technology, Copenhagen, 2010/10/14.
“Fabrication and characterization of SiOx moth-eye structure by room-temperature nanoimprint using
caged- and ladder-HSQ”

4. Yoshitaka Sawa, Kenji Yamashita, Takeshi Kitadani, Daiji Noda, and Tadashi Hattori
Best Paper Award in the Journal of the Society of Plant Engineers Japan
Journal of the Society of Plant Engineers Japan, Vol. 21, No. 1, pp. 7-12, 2009
“Development of High Hardness Micro Metal Mold by Double Layered Electroforming”,

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ACADEMIC DEGREES

Academic Degree

DegreeName

Master’s Thesis

Master ofEngineering

Takeshi Kohmoto(University of Hyogo)

Investigation of transportation property of surface acoustic
waves and its application to powder actuation

Master ofEngineering

Takaya Fujimoto(University of Hyogo)

Development of LED lighting using high performance light guide
plate

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Cover photograph
Lifetime Achievement Award to Professor Hiroo Kinoshita
The cover photograph shows the Medal of the Lifetime Achievement Award toProfessor Hiroo Kinoshita, director of the Center for EUV Lithography at Lasti.
Central five patterns of 12" Si wafer was made by EUV Lithography. Professor
Kinoshita was awarded the prize as inventor of the reduced projection exposure by
extreme ultraviolet lithography.
In 2010, Professor Kinoshita was awarded the 10th Yamazaki-Teiichi Prizefor pioneer of the EUV Lithography and continuous contribution toindustrialization, and was awarded the Medal of Science in Hyogo Prefecture forhis world first proposal using the extreme ultraviolet light lithography technology
in semiconductor processing, and contributed to the practical application todevelop innovative technology.

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LASTI Annual Report 2010

Vol.12(2010)2012.3 Published byLaboratory of Advanced Science and Technology for Industry, University of Hyogo
3-1-2 Kouto, Kamigori-cho, Ako-gun, Hyogo, 678-1205 JAPANTEL: +81-791-58-0249 / FAX: +81-791-58-0242

Editorial board

Editor in Chief
Editors

Shuji Miyamoto
Kazuhiro Kanda
Yoshihiko Shoji
Masahito Niibe
Yuichi Utsumi
Takeo Watanabe

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