Development and Performance of
Kyoto's X-ray Astronomical SOI pixel sensor
T.G.Tsuru (tsuru@cr.scphys.kyoto-u.ac.jp)
S.G. Ryu, S.Nakashima (Kyoto), A.Takeda, Y.Arai (KEK), + SOIPIX group
T. Imamura, A. Iwata, T. Ohmoto, T. Maeda (A-R-Tec) for Chip Design
M. Bautz, G.Y.Prigozhin, S.E.Kissel, B.LaMarr, R.F.Foster (MIT)for experiment of XRPIX1b-CZ-FI/BI
H. Nakajima, H. Tsunemi (Osaka) J.P.Doty (Noqsi) for design of ADC
Ryu et al.
Ryu et al.
Tsuru et al.
Ryu et al.
Nakashima et al.
Nakashima et al.
Ryu et al.
Takeda et al.
Tsuru et al.
Nakashima et al.

IEEE NSS 2010, Conf. Record XRPIX1-CZ -FI
IEEE TNS 58, 2528 (2011)
XRPIX1-CZ-FIIEEE NSS 2011
Review
IEEE NSS 2011, Conf. Record Trigger Readout system
IEEE NSS 2011, Conf. Record XRPIX-ADC1
NIM A Accepted (2012)
XRPIX1-FZ-FIIEEE TNS Accepted (2012)
XRPIX1b-CZ-FI, Inter-pixel cross-talkIEEE TNS Accepted (2012)
Trigger Readout with XRPIX1b-CZ-FISPIE Astro2012
Review
NIM A, Submitted (Pixel 2012) XRPIX2

20121217_国立天文台_可視赤外観測技術ワークショップ_v2.key

内容•SOI / SOIPIX とは？
•Ｘ線SOIPIX検出器•現在の開発状況，到達点•ゲイン，ノイズ，エネルギー分解能•トリガ読み出し•空乏層厚み，裏面不感層，暗電流•今後3はじめに... 2008年11月20日 - 京都新聞(夕刊) -これはもちろん宮崎さんらによる
2k4kBICCDのことです．
HSCの2k4kBICCDとASTRO-HのPchNeXT4は兄弟
光赤外とＸ線 実は欲しい物は似ている．
(裏面照射，厚い空乏層，低ノイズ)

$252,87!77;=5*<8:$!%.,178580A
What is SOI pixel sensor ?

• Monolithic Detector using Bonded wafer (SOI: Silicon On Insulator)• Thick Depletion Layer in the high resistivity Si substrate.
• Standard CMOS circuits can be build in the low resistivity Si.
• Seamless connection between the two layers → No bump bonding.
• Based on Industrial Standard Technology → Stable• No latch Up & High Radiation Tolerance.

SOIPIX Collaboration:
Regular Multi-Project Wafer(MPW) run. (~twice/year)
U. of Hawaii
Fermi Nat'l Accl. Lab.

JAXA

RIKEN

Osaka U.Tohoku U.

KEK

Lawrence Berkeley Nat'l Lab.
Kyoto U.INP Krakow
U. Heidelberg

AIST

Tsukuba U.

IHEP/IMECAS China

Louvain-la-Neuve Univ.

SOIPIX MPW run
Wafer
• PI=Prof.Y.Arai @ KEK, 2005.10~• With OKI semiconductor → Lapis semiconductor• Kyoto joins the collaboration in 2008.

CSOIPIX Applications
EINTPIX : !# b7%'X(23c
ECNTPIX : !, b7S/N,c
ESOPHIAS : XFEL!b7[W]_\X`aYc
EPIXOR : &$6b c
EXRPIX : X(*1!(^WZc
EMALPIX :  .4+)!(5,c
ETDIPIX : X(" +)!
ESTJPIX :0 b/ (dc8
E. . .=>The standard Imaging Spectrometer of
X-ray
CCD
satellites
et al. modern X-ray astronomical[Vol. 59,
Suzaku「すざく」 XIS • Fano limited spectroscopy withthe readout noise ~3e- (rms).

• Wide and fine imaging

with the sensor size of ~20-30mm
pixel size of ~30μm□• Non X-ray background above

Fig. 5. The CCD and heat sink assembly installed in the base. The
cover shield is removed in this picture.

10keV is too high to study
sources.
n alsofaintsupply reverse
current to the TEC, to warm up the

CD chip in orbit. The CCD temperature may be raised a few
ns of ◦C above that of the base. In practice, the requirement tovoid excessive mechanical stresses due to differential thermal
xpansion of the copper heat sink relative to the alumina CCD
bstrate imposes an upper limit on CCD temperature in thisode. For example, with the heat sink at a typical operating
mperature of −35 ◦C, we have adopted a maximum allowble CCD temperature of about + 15 ◦C. The CCD temperature
pper limit is higher at higher heat sink temperatures.

• The time resolution is toopoor (~ sec) to make fast
timing obervation of time
variable sources.

Non X-ray backgroundof XIS (BI)Due to high energy
particles on orbit.

Sensor(high ρ,depleted Si)
Insulator(SiO2)“XRPIX” = Monolithic SOI pixel sensor
for future X-ray astronomical satellites
X-ray

X-ray

V_backElectron
Hole

P+
CMOS
Readout

CMOS
Readout

Fast CMOS(low ρ Si)

CMOS
Readout

V_sig

BPW
CMOS
Readout

non X-ray
BGD(high energy
particle)

scintillatorTimeon-board processor

Our SOIPIX (XRPIX)
Each pixel has its own trigger and Realize Very Low BGD by
analogue readout CMOS circuit.
Anti-coincidence

Imaging
Energy Band
TargetSpectroscopySpecification Timing
Dark Current
Function
Non X-ray BGD

area > 25x25mm2, pixel ~ 30-60μm□ (1” @ F=9m)
0.3-40keV with BI, and thick depletion (>300μm)
ΔE < 140eV @ 6keV, Fano limit (<10e-)<1μsec<1pA/cm2
Trigger signal & pixel address output, built-in ADC
5e-5 c/s/keV/10x10mm2 at 20keV (1/100 of CCD)

Applications for X-ray Astronomy
Ｘ線CCDと明確に違う点（同じ完全空乏・裏面照射，解像度，素子大きさ，ノイズ性能を持った上で）• デジタル(FPGA)だけの簡単な駆動・読み出し回路• 高度なアナログ・デジタル処理機能• トリガ出力可能，高速読み出し，高時間分解能(~μsec)• 反同時計数法による低い非X線バックグラウンド(1/100 @ 20keV)• 高い耐放射線性能考えられるアプリケーション• ASTRO-Hに続く次期中型・大型Ｘ線衛星の焦点面検出器• 全天X線監視モニター，γ線バーストモニター（MAXI, Swift）• 偏光Ｘ線撮像分光器• 惑星探査用X線検出器（高い耐放射線性能）など...

XRPIX1-CZ (X-Ray PIXel detector - CZochralski)◆ CZ (0.7kΩcm), 260μm thick◆ Front Illumination

COL Hit Pattern

ROW ADDR

2.4 mm

1.0 mm30.6 µm x 32 Pixel

COL ADDR
COL Amp

TRIG_COL
TRIG_ROW
Row Hit Pattern

COL Hit Pattern

・O
R

TRIG_OA_OUTXRPIX1: Pixel Circuit
TriggerComparator
VDD18

Trigger
output

GND18

AnalogoutputAnalogReadout
VDD18

SF1

SF2
STORE

CDS

SensorSensor C
Sample C
100fF

PD_VRST

OUT_BUF

G=1

G=1

CDS C
100fF

Sample/Store
GND18

COL_AMPTEST_ECACDS _VRST

VTH

EOXX

XRPIX Series - Road Map -

2010

2011

1.0 mm

1.0 mmXRPIX1XRPIX1b

2012

2013

4.0 mm

4.5 mmXRPIX2XRPIX2b6.0 mm

6.0 mm

2.4 mm

2.4 mmX-ray imaging area

2.4 mm



2.4mm

XRPIX
ΔΣ-typeADC

A-R-Tec PROPRIETARY/CONFIDENTIAL

2.4mm

5

12

Counts

XRPIX1-CZ : X-ray Spectra in the frame mode
160

Red: 109Cd
22.2 keV
Blue: 241Am

250

140

200

120
150

100

Output [ADU]

FWHM = 1.1 keV
13.9 keV
17.7
keV

50

24.9 keV

100

80

60
40

60

80

Good Linearity

100

120

140
Channel40

XRPIX1-CZ(T=-50C, VBB=100V)

Sensitivity = 4.0 μV/e- (including SF, amps)20
Sensor C = 34 fF
Energy Resolution
ΔE = 1.1-1.2keV (FWHM) ≫ Fano limit
Readout Noise = 100e- (rms)

0
0

5

10
15
20
X-ray Energy [keV]25

Ryu et al., IEEE TNS 58, 2528 (2011)

XRPIX1-CZ : Readout Noise• See whether the readout noise of 100e- (rms) is The sum of these noises
explained by the sum of circuit noises or not.
• Measure the noise of individual circuit element
through several DC voltage input points.
VDD18

SF1

SF2
STORE

CDS

SensorSensor C
Sample C
100fF

A

PD_VRST

OUT_BUF

G=1

G=1

Vout
TEST_ECACDS _VRST

VBB
SF1
13e

COL_AMP

CDS C
100fF

Sample/Store
GND18

is almost consistent
with the observed
readout noise of 100e.

CDS kTC
70e(100fF 51e)
Sum = 94e

EOXX

VTH

VCC

VDD

SF2 COL_AMP OUT_BUF
External
13e
31e
on PCB
53e
Ryu et al., IEEE TNS 58, 2528 (2011)

XRPIX2-CZ-FI (Small Pixel) : Spectrum
Cu Kα (8.0 keV)

Mo Kα (17.4 keV)

150

1800

1400

800 eV
FWHM
100
Mo Kβ
(19.6 keV)

656 eV
FWHM

1200
1000
1000
800
600

500
400

Pulse Hight (ch)Cu Count

1500

Mo Count

200

1600

120
100
100
80
60

50

XRPIX1 Gain
3.6 µV/e-

40
20

200

00

XRPIX2 Gain
6.5 µV/e-

140

0
80
40
120
160
Pulse Hight (ch = 244 µV)
40

60

80

100

Observed
Cu Kα

656 eV

Mo Kα

800 eV

120

140
160
PH [ADU]

Readout
Noise

000
0

Fano
Noise

548 eV (FWHM) 139 eV
64 e-(rms)
205 eV

2

4

10
12
14 16
10
X-ray Energy (keV)
6

8

18

Pixel-Pixel Gain
Dispersion 1%Sum

255 eV620 eV553 eV805 eV

20
20

Nakashima et al., 2012, NIM A submitted

XRPIX1b-CZ : Single Pixel Readout• In order to study the limit of the spectroscopic performance.
• Observe the waveform of analogue output from a single pixel by fixing the

120

655

average
100 samples
645
τ=100μsec
X-ray Pulse
640
Hit HeightCMS Histgra (R10C10)
PH [ADU]

660

Cts / ADU

PH [ADU]

readout address without clocking (Single Pixel Readout like a SSD).
• Detect an X-ray as a “step” and measure the pulse height. → X-ray spectrum.
• No reset during the measurement → Free from the reset noise• Reduce noises other than the reset noise by introducing LPF.
high_v(100 samples average) - low_v(100 samples average) → LPF with τ=100μs633

rms=14.6e-

100

632

650

635

average
100 samples
τ=100μsec

630
625
0

200

400
600
800
1000
sample number in one frame

44M-BPW

631

80

630

60

629

40

h1
Entries398490Mean
0.3396RMS
3.101
χ2 / ndf
3.97e+05 / 9
Constant
85.81 ± 1.41
Mean
54.28 ± 1.41
Sigma
0.8022 ± 11.6984

Cu-Kα

FWHM=278eV@8.0 keV

628

20

0

Nakashima
et al.,
0
200
400
600
800
1000
2012,
one frame
20
40
60sample
80 number
100 in120
140
NIM A
PH [ADU]
readout noise = 14.6e (rms) accepted627

0

ΔE = 278eV @ 8.0keVh1(FWHM),
CMS Histgram

Cu-Kβ

XRPIX1b-CZ : Trigger Driven Readout
③・

④

④

TRIG_ROW①①
X-ray !

Row Hit Add.
Resister

ROW Readout ADDR

COL Hit Add. Resister

TRIG_COL

COL Readout ADDRCOL AmpO
R

TRIG_O

F
P
G
A

②
A_OUT

ADC

⑤
Takeda et al., IEEE
Accepted (2012)

XRPIX1b-CZ : Trigger-driven Readout of X-ray Events
Transactions
on Nuclear Science X-ray- Copy for
Review
Trigger
Address
Trigger-driven
Spectra!
TAKEDA et al.:Trigger
DESIGN AND EVALUATION
OF A SOI PIXELSENSOR FOR X-RAY TRIGGER-DRIVENREADOUT
Readout
Clock70

TRIG_OUT
SCLK

Data

60

Calibration

ADDR[0]2μsec

CA[26]

RA [31 - 0]
RA[7]Raw X-ray trigger signals recorded by the oscilloscope (c.f., Fig.

CountsAddress of Column Row
Triggered
Pixel
45

VTH : 10 mV
Exposure : 5 sec

8 keV- Trigger-driven
mode basically
35
30 operates as designed.
25

0
0

1

0.8

VTH h1
Exposure

Entries 1617
Cu+Mo 10Mean
mV 5sec
58.61
RMS
19.57

Am-241 15 mV 20 sec

500.9

h1

8 keV

Entries 487
Mean 39.51
RMS
10.58

17.4 keV

0.6
0.5

FWHM
20
1.4 keV
0.3
0.4

100.2
0.1

40

0

Mean

5

30

CA [31 - 0]

Fig. 12.
9).

Entries
RMS

400.7

ADDR[31]13.9 keV

h1

Trigger Assert Probability

Counts / ADU

5 of 6

FWHM

0 0
400

VBack = 100 V

17.7 keV

-10 ℃

26.4
keV
-30 ℃
-50 ℃

20
40 50060 80
100600120 140
160
450
550
650
X-ray PH
(ADU)
Input Voltage(mV)

Fig. 14. Dependence of the trigger output on the input signal at a fixed
threshold voltage of 500 mV. The trigger assert probability is calculated fromthe fraction of trigger-on events after 10000 tests at the corresponding input
voltage.

- The gain is different from thatof the frame mode.
because in this case Cu K↵ and K lines are not separsated.
- We
are value
nowis investigating.
The energy
resolution
used for comparison with thetrigger-driven mode described in section IV-B. The ADC gain

Takeda et al., IEEE Accepted (2012)

Depletion Depth [um]

XRPIX1-FZ (7kΩcm): Depletion Depth350

FZ : 250μm @ VBB=30V

300
250
200

CZ : 150μm @ VBB=100V

150
100

+ : Experimental results– : Expected value

50
0
0

10

20

30

40
50
Back Bias [V]

60

70

80

90

100

110

• The X-ray measured thickness of the depletion layer of XRPIX1-FZ
reaches ~250μm at 30V and stops its growth there.
• The 250μm is nearly equal to the hi-ρ Si thickness (260μm).
• Full depletion is achieved at VBB=30V.

Nakashima et al., 2012, NIM A acceptedXRPIX1-FZ-FI (7kΩcm) : Dark (Leak) Current
Requierment at -40C
= 0.1e/msec/30.6μm□ pix(depletion = 250μm)= 2pA/cm2

Dark Current (e/msec/30.6μm□
pixel)
Dark Current (e/ms/pixel)

XRPIX1-FZ，with CMP
PchNeXT4 (normalized to 30.6μm□)
106
105 黒：VBB=30V
4

10

青：20V
赤：10V

103
102
10

1/100

1
10-1
10-2
10-3

3e-2

PchNeXT4

4e-3
-50

-40

-30

-20

From 20110516_OKImeeting_SOI_Dark_v5

-10
0
10 20
Temperature (degree C)

20

Dead Layer = Si 0.1μm

Si 1μm

QE
0.5

1.0

Back Illumination is Essential

0

Si 10μm0.3

1.0Energy(keV)

5.0• Scientific Target : observe C-Kα X-ray line at 0.3keV.
• The front side of SOIPIX has a circuit-layer of 10μm thickness.
(Note: XIS FI-CCD~1μm, BI-CCD~0.07μm)• Difficult to detect Soft X-rays with FI.
• Difficult to reduce the thickness of the circuit layer.

→ BI is essential

QE of LBNL’s BI-SOIPIX / SOImager-2-CZ-BI
Dead Layer
0.6±0.2μm
Deplation73±2μm• CZ-BI with Back-thinned to 70μm.
• A thin phosphor layer is implanted.

Battaglia+12 NIM-A※ これは我々の素子ではなく，同じウェハを使用した別の素子です．

XRPIX1b-CZ-FI/BI (100μm): Spectra in Single Pixel Readout (2011.11.22)

Cts

Target= Al2O3 , Front-I, Back-I, V_tube=6 kV,
V_bais = 100V, Temp=–50ºC, Hit Threshold= 2 ADU, Exposure=400 sec, PIX=R10C10, 2us_sample, 300 µs_ave
CMS Histgram (offset-corrected)

RED: BI BLUE: FI←15 e-rms

h4

Cts

CMS Histgram (offset-corrected)

1200←18 e-rms

4

10

Entries
Mean
RMS

h4

1100

103

900
800

502 eV

400• ΔE (FI) = 188eV,

300
200
100

2

10

0

6kV).
(+O-K from Al2O3?)

by
Calibration

500• X-ray generator (target = Al,• Al-K + Bremss

3.417

RMS

700
600

O-Ka ??

Zoom

Entries 128627
AL-Ka 1.608
Mean

1000

AL-Ka
(1.48 keV)

1286272.282
3.155• Back illumination type.

0

1

2

3

4

5

6

7

8

9 10 11 12 13 14
PH [ADU]

ΔE (BI) = 351eV (if line)

HV
(6kV)

10

1

-5

Detection
Threshold(2ADU)

Si Edge(1.84 keV)

0

10

5

15

20

25

30

35 40
PH [ADU]
Results on FI : Ryu et al., IEEE Accepted (2012)

XRPIX3 and afterSpectral Performance•全てのピクセルにチャージアンプを持つ•ノイズ性能の改善，エネルギー分解能の改善
Backside•裏面プロセスの改良•暗電流の削減とデットレイヤーを薄く→以上の要素技術の合体
System•反同時計数システムの試作•非Ｘ線BGDの減少の実証•外部回路のノイズ削減

Conclusion• Ｘ線天文衛星用のＸ線SOIピクセル検出器(XRPIX)を開発．
• 反同時計数による低非Ｘ線BGDを目指し，トリガ機能を持つ．
• 4.5mm角の素子の開発に成功• 空乏層厚み~250μm，裏面不感層~0.6μm• 読み出しノイズ64e-(rms)，ΔE=656eV @ 8.0keV (FWHM)• トリガ読み出しに成功• 今後，読み出しノイズ，裏面不感層，反同時計数の実証を行う

A-R-Tec

Analog and RF Technologies

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URL: http://www.
Email: info@a-r-teĀ@ŊĐĬłě&²üÝÖ&²ÿ½óČŒ©¨ŔªM£Ā»œüŒµüñú3[ñň\`Ā}iü0M£Ā7ÿ®yóČîüŉÍ