Bull. Hiroshima Inst. Tech. Research Vol.48（2014）105-114

Report

The report of joint research over 20 years of the Bulgarian Academy of
Sciences and Hiroshima Institute of Technology

Takeshi TANAKA* and Katia VUTOVA**（Received Oct. 17, 2013）

Abstract
The Department of Electronics and Computer Engineering, Hiroshima Institute of Technology(EC-HIT) started the international joint research with the Laboratory“Physical Problems of Electron Beam technologies”of the Institute of Electronics, Bulgarian Academy of Sciences (IE-BAS)
from 1994. 20 papers, included a book chapter, were published by implementing the international
joint research under 5 Agreements for Academic Cooperation and Exchange between HIT and IEBAS. Our international joint research is getting the important position in joint research between Japan and Bulgaria.
(The ﬁrst Agreement for Academic Cooperation and Exchange between the Hiroshima Institute ofTechnology and the Institute of Electronics of the Bulgarian Academy of Science was signed in
1998. The President of HIT and the President of the BAS and the Director of IE-BAS signed the 4thAgreement in May 2009 and the 5th Agreement was signed in 2012.)
The semiconductor fabrication process such as thin ﬁlm deposition, Electron and Ion Lithography, Etching, Ion implantation, Plasma treatment, etc., evaluation technique such as X-ray photoelectron spectroscopy, optical spectroscopy, X-ray diffraction, etc., and their simulation technology
were used for application in industry, medical service, medicine manufacture, biotechnology, dental,etc.
In the future, this bilateral research partnership between EC-HIT and IE-BAS becomes more stable and further develops the bilateral relation between HIT and BAS.
Key Words: joint research, Institute of electronics at the Bulgarian Academy of Sciences, Hiroshima

Institute of Technology

1. Introduction

The Department of Electronics and Computer
Engineering, Hiroshima Institute of Technology (ECHIT) started the international joint research with theLaboratory“Physical Problems of Electron Beamtechnologies”of the Institute of Electronics, Bulgarian Academy of Sciences (IE-BAS) from 1994. 20 papers, included a book chapter, were published by implementing the international joint research under 5＊＊＊＊＊＊

Agreements for Academic Cooperation and Exchange between HIT and IE-BAS. Our international
joint research is getting the important position in
joint research between Japan and Bulgaria.
(The ﬁrst Agreement for Academic Cooperationand Exchange between the Hiroshima Institute ofTechnology and the Institute of Electronics of the
Bulgarian Academy of Science was signed in 1998.
The President of HIT and the President of the BAS
and the Director of IE-BAS signed the 4th Agreement

Department of Electronics and Computer Engineering, Hiroshima Institute of Technology, Hiroshima, Japan
Institute of Electronics, Bulgarian Academy of Sciences, Sofia, Bulgaria― 105 ―

Takeshi TANAKA and Katia VUTOVA

in May 2009 (see Fig.17) and the 5th Agreement was
signed in 2012.)
The semiconductor fabrication process such asthin film deposition, Electron and Ion Lithography,
Etching, Ion implantation, Plasma treatment, etc.,
evaluation technique such as x-ray photoelectron
spectroscopy, optical spectroscopy, x-ray diffraction,etc., and their simulation technology were used for
application in industry, medical service, medicine
manufacture, biotechnology, dental, etc..
In the future, this bilateral research partnership
between EC-HIT and IE-BAS becomes more stableand further develops the bilateral relation between
HIT and BAS.

equipment and information technologies. The Institute was relied on to become the academic motor in
the drive of laying the scientific foundations andforming the research cadres necessary for the nascentelectronic stage of Bulgaria＇s development.
In its quality of a part of the Bulgarian Academyof Sciences, the Institute＇s mission is to acquire, accumulate and disseminate scientiﬁc knowledge andtechnologies in its research ﬁeld, thus contributing to
Bulgarian people＇s intellectual and material enrichment and to widening humankind＇s scientific horizons.

Mission of the Bulgarian Academy of Sciences1)

The Bulgarian Academy of Sciences is dedicated to the development of science in conformity withthe universal human values and with the country＇s
national interests and promotes the enhancement of
the intellectual and material wealth of the Bulgarianpeople.
50th ANNIVERSARY OF ACADEMICIAN EMIL DJAKOVINSTITUTE OF ELECTRONICS2)

Fig. 1 50 years Institute of Electronics“Acad. Emil Djakov”–
June 2013.

In 2013, the Academician Emil Djakov Instituteof Electronics of the Bulgarian Academy of Sciences
turns 50. It was established on September 27, 1962,
by a Resolution of Bulgaria＇s National Assembly andbegan its independent existence in 1963 based on the
Physical and Applied Electronics Section formed in1948 at the Institute of Physics of the BAS by the Institute of Electronics ＇ founder, first Director andbuilder, Academician Emil Djakov. Initially, the Institute had 30 employees and comprised two sections
and two laboratories located on the fourth floor of
the Institute of Physics＇ new building. According to
the Resolution of September 27, 1962, the Institute ofElectronics＇ scope of activities was academic research in the fields of cathode electronics, electrovacuum microwave devices, quantum electronics
and applied electronics. At the time, the term Electronics included the set of fundamental knowledge,
technologies and algorithms for the development andmanufacture of the electronic components necessary
for creating modern communications, computing

Through the years, the Institute＇s research ﬁeld
and structure have developed dynamically in response to the changes taking place in the main trends
in applied physics and technologies: materials science and technologies, physics of nano-sized objects
and nanotechnologies, nanoelectronics, photonics,
opto-electronics, quantum optics, environmental
physics and monitoring, biomedical photonics andbiomedical applications.
The Institute＇s main areas of scientiﬁc development have been preserved, while the specific research today takes into account the contemporary
problems and requirements, the world-wide tendencies and Bulgaria＇s speciﬁcity and traditions.
The research efforts in physical electronics areconcentrated on studying and solving the problems
of generating and controlling electron and ion beams
and their interaction with materials. This includes
theoretical modeling, modern techniques, researchand industrial equipment for micro- and nano-struc-― 106 ―

The report of joint research over 20 years of the Bulgarian Academy of Sciences and Hiroshima Institute of Technology

turing, thin ﬁlms deposition and study, modiﬁcationof surfaces, vacuum melting and welding of metals
by intense electron beams. The physical basis is being formed of creating nanostructures, nanomaterials
and nanoelements by using electron and ion beams.
Furthermore, fundamental properties are being investigated of gasses and gas plasma, plasma arcs andplasma torches in view of developing diagnostic
techniques and applications in thin ﬁlms depositionand plasma chemistry.
The research in photonics and quantum electronics comprises theoretical and experimental studies on the interaction of short and ultrashort lasers
pulses with matter; development of novel nanostructuring technologies; laser thin-films deposition andtreatment; light-induced absorption and transmissionin alkaline vapors; development of complex laser
systems for analysis and modification of semiconducting and superconducting materials; theoreticaland experimental investigation of non-linear opticalphenomena; biomedical photonics.
The research efforts in radiophysics are directed
to clarifying the processes of interaction of opticaland microwave electromagnetic radiation with theatmosphere and the Earth＇s surface; developing experimental systems for laser remote sensing andmonitoring of the atmosphere; microwave remote radiometric measurement of soil moisture content; developing algorithms and techniques for signals andinformation processing; constructing microwave
units and systems for radar and communication applications; studying non-linear processes in opticalcommunication media. New ferrite devices with micrometric dimensions were developed with possibility for higher degree of integration. Active researchon gyro-magnetic materials is underway, in view ofreaching higher frequency ranges, especially mmwaves for wireless communications and protection
from powerful microwave radiation.
In all three ﬁelds of research, the Institute＇s scientists have achieved internationally-recognized priority by discovering new physical phenomena andrelations, among which are particularities in the interaction of electron and ion beams with materials;
ion channeling in the semi-channels of a crystal surface and hyper channeling at grazing angles; ion-stimulated sorption; plasma electrodes for gas lasers;
electromagnetically induced absorption in Hanle
conﬁguration.
During the 50 years of the Institute＇s existence,
its scientists have published over 7000 scientiﬁc papers that have been cited more than 4500 times. The
Institute has taken an active part in the international
scientific cooperation by establishing partnerships
with scientiﬁc research institutions of the USA, Russia, France, Germany, Japan, India, Italy, Poland, theCzech Republic, Slovak Republic, Sweden, Ukraine,
Canada, Finland, and Vietnam. In recent years, in its
collaboration with the European scientific research
institutions, the Institute has placed the accent on
joint work within the framework of the European
priority research programs.
The Institute has represented Bulgaria in international scientiﬁc organization, such as the International Institute for Weights and Measures, the International Laboratory of Low Temperatures and High
Magnetic Fields in Wroclaw, Poland, the European
Physical Union, the International Union for Pure andApplied Physics, the International Union on Vacuum
Physics and Applications, the International Radiosciences Union, the NATO Advanced Study Institute, as
well as in the editorial boards of reputable international scientiﬁc journals.
The following important innovative technologies and devices have been developed for the firsttime in Bulgaria in laboratory conditions, mastered
technologically and made available to the Bulgarianindustry and economy: lasers, lidars, electron lithography systems and installations and technologies forelectron beam melting, welding and reﬁning of metals; plasma torches, electro-optical converters with amicro-channel plate; technology for optical fibers
production; electron and ion projectors; ion technologies and systems for deposition of thin wear-resistant coatings; low-noise parametric solid-state microwave amplifiers; line- and strip line circulators;
converters; microwave absorbers; microwave ampliﬁers, SQUID devices; portable microwave moisture
meters for bulk materials; microwave radiometersand systems for remote soil moisture sensing; a mobile laboratory for remote microwave sensing of sea
and land surfaces; magnetometers based on various― 107 ―

Takeshi TANAKA and Katia VUTOVA

principles; ultra-high vacuum pumps and installations; devices and installations for studying the surfaces and properties of semiconducting materials;
optical gas sensors; technologies and systems fornanoparticles and nanostructures formation; a technology and installation for nano powders production; industrial and medical laser and plasma technologies and installations; optical and microwave
communication systems. Proofs of the above
achievements have been participation in and awards
from numerous industrial exhibitions and fairs and alarge number of practical developments and industrial implementations resulting in revenues for the Bulgarian economy measured in millions of BGN or
foreign currency. Gradually, the Institute acquired
the role of a secondary center for education of scientists and dissemination of knowledge and methodologies in Bulgaria and abroad. Under the conditionsof a free and ﬁerce competition, the Institute won thestatus of a center for and a coordinator of the research on lasers and lidars, remote microwave sensing of sea and land surfaces, remote radiometric microwave sensing of soil moisture, electron beam andplasma technologies, microwave solid-state electronics.
Through the years, the Institute has provided thescientific ambiance and opportunities that allowed
the formation and successful scientific carriers of
one academician and three corresponding membersof the Bulgarian Academy of Sciences, 18 professors, 21 doctors of sciences and 111 PhDs; 37 former
members of the Institute＇s research staff are now
working on leading positions at research institutionsin the USA, Sweden, Canada, France, Great Britain,
Switzerland, Germany, Vietnam.
The Institute＇s staff has been instrumental in thedevelopment and advancement of highly efficienttechniques for and approaches to implementing scientific products in the industry, agriculture, publichealth and defense by way of joint development programs, inter-branch and joint laboratories, experimental installations and workshops for pilot production; research and development of technologies,
measuring and technological equipment, single devices and technologies; training of specialists.
During the Institute＇s existence, its work andstaff have been evaluated several times by the Bulgarian Academy of Science and other national institutions having the relevant authority, as well as twice
by prestigious international commissions. With noexceptions, the marks have been high, accompanied
by recommendations for further development andexpansion.

Fig. 2 Academician Emil Djakov – founder of the Institute ofElectronics.

The IE-BAS and the laboratory“Physical Problems of Electron Beam Technologies”is a leading
research and development unit of BAS that is doing
theoretical and experimental research connected withthe application of electron beam technologies in science, industry and other areas. The laboratory research and development and innovation activities include: physics and characterization of intenseelectron beams, theoretical and experimental studyof electron and ion penetration in materials, mathematical models and computer simulation of processes at sub-micron and nano-dimensional electron andion lithography, electron beam welding, surface
modification by thermal treatment, electron beam
melting and reﬁning of metals and alloys, new materials, thin ﬁlms, modeling and computer simulationand improvement of processes, computer simulationof signals at investigation of surfaces and thin ﬁlms
by electron spectroscopy, development and application of statistical methods for control and optimization of electron beam technologies. The ﬁrst Bulgarian installations for electron beam melting andreﬁning of metals, for electron lithography, and electron beam welding have been set up in the IE-BAS.
The gained knowledge and experience of the― 108 ―

The report of joint research over 20 years of the Bulgarian Academy of Sciences and Hiroshima Institute of Technology

group in the Laboratory“Physical problems of electron beam technologies”, the obtained scientific results and the established international connections
are contributions that gave a lot to physical electronics, vacuum and micro- and nano-technologies, andnew materials and have great potential for future development. They rise the level of the Bulgarian science and ﬁnd new applications in the industry.

Fig. 3 Poster of the Laboratory“Physical Problems of Electron
Beam Technologies ”for the 50 th anniversary of theInstitute of Electronics“Acad. Emil Djakov”.

Fig. 4 Researchers from Lab.“Physical Problems of Electron
Beam Technologies”, IE-BAS, May 2013.

The IE-BAS and particularly the Laboratory“Physical problems of electron beam technologies”
is a creator and organizer of the International Conference on Electron Beam Technologies (EBT). Thisconference takes place in Bulgaria every three years,
starting in 1985. The fact that the conference takes
place in Bulgaria is a sign of recognition from the in-ternational community of scientists and industrial
experts for the contribution of the Bulgarian scientists in the development of those technologies andtechnique and for their efforts for the effective conduction of the forum. During the EBT conferences
physicists, chemists, and engineers from research
and academic organizations and from the industry
meet. The full text of the presented papers and lectures during the EBT＇2000, EBT＇2003 and EBT＇2006
after the reviewing were published in the journals
Vacuum v. 62, (2001); Vacuum v. 77 (4), (2005);“Elektrotechnica & Elektronica”, v. 5-6, (2006), (2009).
The latest 10th meeting (EBT＇2012), as all nineprevious ones, provided an excellent forum for exchange of results, experience, knowledge and ideas
in the development of EB technologies. As usual, it
was also a place for establishing personal and business contacts and funding partners for joint work
programs and networks. The anniversary 10th EBT
Conference owes its success to all participants, to theInternational Organizing Committee and to the Local
Committee.
The Conference proceedings was printed anddistributed as a regular issue of the mostrespected Bulgarianscientiﬁc and technical journal in ourﬁeld Elektrotechnica& Elektronica (h t t p : / / w w w. c e e c .
fnts.bg/sp-E+E.
htm), v. 5-6 , 2012 .
The number of published papers is 62,
representing the research results of 176 scientists
from academic institutions or industry of many countries: Germany, Russian Federation, Ukraine, Czech
Republic, Slovak Republic, UK, Japan, Romania,
France, Algeria, China, India, etc. Leading companies, such as ALD Vacuum Technologies GmbH,Hanau, Germany; VON ARDENNE, Dresden, Germany; JSC “NVO “Chervona Hvilya ”, Kiev,
Ukraine; TWI, Cambridge, UK; TARGETS LTD,
Plovdiv, Bulgaria had the opportunity to present theirlatest e-beam equipments and products.

― 109 ―

Takeshi TANAKA and Katia VUTOVA

searcher in HIT (February 1998), invitation from
T.Kawasaki, M.D., Ph.D - President of the Hiroshima Institute of Technology, Hiroshima, Japan,
Lectures on“Mathematical modeling and computer simulation of the processes in electron and ion

The following main activities concerning the
successful collaboration between the Hiroshima Institute of Technology (HIT) and the Institute of Electronics of the Bulgarian Academy of Science (IEBAS) during the last 20 years can be mentioned:
1. During the last 20 years under 5 Agreements for

Academic Cooperation and Exchange between
HIT and IE-BAS joined results in the field of
modiﬁcation and computer simulation of the processes of electron, ion and x-ray radiation of electronic materials have been obtained. The results
were published in more than 20 common publications in one Chapter in book, in journals and conference proceedings and these common papers arecited more than 25 (see the list of common papers
below).
Our results concerning the computer simulationof signals at investigation of surfaces and thin ﬁlms
by electron spectroscopy are summarized and published in a Chapter in a special review book“Practical Aspects and Applications of Electron Beam Irradiation”[5]. The angle-resolved XPS is a promising
surface-sensitive electron spectroscopy method fornon-destructive depth-proﬁle analysis in a few nanometers in depth. The developed and presented model
for computer simulation of the XPS angular intensity
distributions and the obtained results can be used todescribe investigations at real surface structures (foranalysis of electron spectra generated from textured
surfaces, including also the shadowing effect). Surface roughnesses, which are important phenomena atreal samples, were modelled by different 3D geometrical shapes of variable size. This computer simulation helps to understand the behaviour of measured
angular XPS signal distributions, provided that theapproximation of the textured surface resembles theanalyzed sample surface. The height of the investigated surface roughnesses is similar to the ones
studying using microscopy, based on the atomic
forces and potential, as well as scanning electron-microscopy methods. This approach allows developing
XPS profilography using the integral evaluation of
the surface roughnesses (instead of obtaining many
proﬁles and subsequent mathematical processing).
2. Prof. Katia Vutova was invited as a guest re-Fig. 5 Noboru Tsuru, founder of the Hiroshima Institute ofTechnology (left) and Prof. K.Vutova (right)

Fig. 6 T akashi Kawasaki, President of the Hiroshima Institute ofTechnology was presented.

Fig. 7 Prof. K.Vutova ＇s lecture in the Hiroshima Institute of― 110 ―

Technology.

The report of joint research over 20 years of the Bulgarian Academy of Sciences and Hiroshima Institute of Technology-“Bulgarian Academy of Sciences – history andpresent”-“Institute of electronics – laboratories, activities
and collaborations”-“Electron and Ion Beam Lithography – physicalprocesses, computer simulation and experimental
data”-“Ion Scattering Modeling in Amorphous Targets”

Fig. 8 Prof. K.Vutova was presented in the Hiroshima Instituteof Technology.

Fig. 11 Hiroshima Institute of Technology ＇s students present

experiments to Prof. K.Vutova.

Fig. 9 After Prof. Vutova＇ lecture, commemoration photography

with students from the Hiroshima Institute of Technology.

Fig. 12 Meeting of the audience of Prof. Vutova＇ lecture in frontof the gate of the Hiroshima Institute of Technology.

-“Introduction in mathematical analysis”
Fig. 10 Commemoration photography with the Hiroshima
Institute of Technology＇s students.

4. In 2004 The Executive Council of the BAS con-lithography”. (see Figs.5-12 ).
3. In December 2003 Prof. K.Vutova was invitedfrom Dr. of Eng. Kazu-hiro MORI - President of
the HIT, Hiroshima, Japan. She also visited thecompany“Soken Kogyo CO.”, LTD. Kawagoeshi. Presented lectures:― 111 ―

ferred the Decoration of Honour“FOR SPECIAL
MERIT TO THE BULGARIAN ACADEMY OFSCIENCES ”on Prof.K.Kawabata and Prof.
T.Tanaka for their merit to IE-BAS and their contribution to promoting the cooperation between
HIT, Hiroshima and IE-BAS, Soﬁa in the ﬁeld of
the interaction between electrons and ions withdifferent materials. (see Fig.13). [3]Takeshi TANAKA and Katia VUTOVA

Fig. 13 Prof. Kawabata and Prof. Tanaka were awarded theMedal of Honor for“Special achievement to Bulgarian
Academy of Sciences ”on December 1 , 2004 . The

Fig. 15 A cademician Sendov (right) – Ambassador of the

Bulgarian Embassy in Japan, Tsuru (left) - Chairmen of
the board of directors and the presidents of a university
during exchange of opinions in the Tsuru school andHiroshima Institute of Technology, May 8, 2008.

certiﬁcates and badges were presented to both of themby the Bulgarian Academy of Sciences. [3]5. Prof.K.Kawabata (since 2000) and Prof.T.Tanaka(since 2006) were members of the International
Organizing Committee and attended many times
the International Conference on Electron BeamTechnologies, organized by IE-BAS every 3 years
in Varna, Bulgaria.

Fig. 16 Prof. Tanaka explains the Automatic control model toAmbassador Sendov and accommodation persons.

Fig. 14 Prof. Mladenov and Prof.Vutova exchange experience
with Prof. Takeshi Tanaka in IE-BAS, June 18, 2008.

6. Since October 2009 Prof.T.Tanaka is a member of

the International Editorial Board of the scientiﬁcjournal“Elektrotechnica & Elektronica ”, published by the Union of Electronics, Electrical Engineering and Telecommunications (CEEC), Bulgaria. [4]Fig. 17 Academician N.Sabotinov (President of BAS, front row

7. Since December 2009 Joint Electronics ResearchCenter in HIT and in IE-BAS is established. Coordinators: Prof. Takeshi Tanaka from HIT and
Prof. Katia Vutova from IE-BAS.

― 112 ―

center) shaking hands with Dr. TANAKA (HIT, front
row left). Prof. Vutova (IE-BAS, front row right), Mr.
Imamura (President, Bulgaria Association of Hiroshima,
back row left), Mr. Yamamoto (Director, Bulgaria
Association of Hiroshima, back row right).

The report of joint research over 20 years of the Bulgarian Academy of Sciences and Hiroshima Institute of Technology

List of the common papers:
1.

G.Mladenov, K.Vutova, T.Tanaka, K.Kawabata,“X-ray Photoelectron Profilography ”, Journal of

Surface Analysis, v.5, No 1, (1999), 82-85.
2.

K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,“Evaluation of thin film surface topology shapes”,

Mathematics and Computers in Simulation, v.49, No
4-5, (1999), 275-283.
3.

K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,“Photoelectron Signal Simulation from Textured

Fig. 18 Surround the Japanese wrapping cloth of the peace ofOverlayer Samples”, Surface and Interface Analysis,

Hiroshima Institute of Technology.

30, (2000), 552-556.
4.

K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,“Photoelectron signal simulation from textured

samples covered by a thin ﬁlm”, Vacuum, 62, (2001),
297-302.
5.

K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,“Photoelectron Signal Simulation from Textured

Samples with Modified Surface Composition ”,
Surface and Interface Analysis, 34, (2002), 597-600.
6.

K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,“Simulation of the energy absorption and the resist

development at sub- 150 nm ion lithography ”,
Fig. 19 Ambassador Sendov＇s farewell party on September 12,
2009 in Republic of Bulgaria ambassador ＇s official

residence in Japan.

Microelectronic Engineering, 78-79 (2005), 533-539.
7.

K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,
I.Raptis, A.Olzierski,“Modeling of resist exposureand development for optimization of sub-quartermicron patterns”, International Journal IEEE - Annual
School. Lectures., 25(2), (2005), 13-16.

8.

K.Vutova, G.Mladenov, T.Tanaka, T.Takagi,“Investigation of ion penetration in silicon during

plasma-based ion implantation”, Journal Physics, 49(8), (2006), 216-218.
9.

K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,“UseXPS to characterize the surface roughness”Proc. ofFig. 20 The 48 th time and a regular meeting (an executive
director and executive board ) 17:00 on Sat., March 9,2013 in the Hiroshima foreign student hall adviser ＇s

the National Conference with International
Participation“Electronika ＇96”, Botevgrad, Publ.

Foreign Minister, Fumio Kishida, participates andencourages.

UEEEC, (1998), 29-35 (in Bulgarian).
10. G.Mladenov, K.Vutova, K.Kawabata, T.Tanaka,“XPS

profilography through angle resolved spectra”, Proc.
of the National Conference with International
Participation“Electronika ＇98”, Botevgrad, Publ.
UEEEC, (1998), 36-41.
11. K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,

I.Rangelow,“Electron and ion beam lithography― 113 ―

Takeshi TANAKA and Katia VUTOVA

simulation for sub-quarter-micron patterns”, Proc. of“Nonlinear solubility behavior of polymer andthe 7th International Conference on Electron Beamoligomer resists at electron beam modification ”,

Technologies, EBT＇2003, Varna-03, (2003), 469-481.

presented at the 1 st International Symposium on

12. Vutova K., E.Koleva, T.Tanaka, T.Takagi, G.

polymer modification with high energy electrons

Mladenov,“Ion modification of plastic materials ”,(POLYWHEEL 2010 ), 24-26 Nov 2010 , Dresden,

Proc. of the National Conference with International

Germany, Abstract Book, 44 (2010).

Participation“Electronika＇2004”, Sofia, Publ. UEEE

21. K.Vutova, E. Koleva, G.Mladenov, I.Kostic, T.Tanaka,

Bulgarian Section, (2004), 93-101.

“Computer simulation of resist profiles at electron

13. K.Vutova, G.Mladenov, T.Tanaka, T.Takagi,b e a m n a n o l i t h o g r a p h y ”, M i c r o e l e c t r o n i c s“Investigation of ion penetration in silicon during

plasma-based ion implantation”, Journal Electronics

Engineering, 87, (2010), 1108-1111.
22. K . Vu t o v a , G . M l a d e n o v, E . K o l e v a , I . K o s t i c ,and Electrical Engineering, 5-6, (2006), 186-188.

A.Bencurova, P.Nemec, T.Tanaka, “Nonlinear

14. T.Tanaka, K.Vutova, E.Koleva, G.Mladenov, T.Takagi,

solubility behavior of polymer and oligomer resists at“Surface modification of plastic films by charged

electron beam modification”, Journal of Materials

particles ”, presented at the Sixth International

Science and Engineering B, 1, 523-529, (2011).

Symposium on Polymer Surface Modification, June

23. K.Vutova, G.Mladenov, T.Tanaka,“Photoelectron

11-13, 2007, University of Cincinnati, USA.

signal simulation at surface analysis”, Chapter in a

15. K.Vutova, G.Mladenov, T.Tanaka, K.Kawabata,s p e c i a l r e v i e w b o o k “P r a c t i c a l A s p e c t s a n d

I.Rangelow,“Electron and ion beam lithography

Applications of Electron Beam Irradiation ”, еds.:

simulation for sub-quarter-micron patterns ”, Nano

M.Nemtanu, M.Brasoveanu, publ. Research Signpost/

Trends: A Journal of Nanotechnology and its

Transworld Research Network, 235-254, (2011).

Applications, 2 (1), (2007), 32-47.

Acknowledgement

16. K.Vutova, E.Koleva, G.Mladenov, I.Kostic, T.Tanaka,

K.Kawabata,“A simulation model for ChemicallyA m p l i f i e d R e s i s t C A M P 6 ”, M i c r o e l e c t r o n i cEngineering, 85, (2009), 714-717.
17. T.Tanaka, K.Vutova, E.Koleva, G.Mladenov, T.Takagi,“Surface modification of plastic films by charged

particles”, Polymer Surface Modiﬁcation: Relevance

The authors express gratitude to HIT and BAS
for their support of the joint research and the successful cooperation between the Institute of Electronics at the Bulgarian Academy of Sciences, Soﬁa,
Bulgaria and the Hiroshima Institute of Technology,
Hiroshima, Japan during all 20 years.

to Adhesion, K.L.Mittal (Ed.), VSP/Brill, Leiden, Vol.

References

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simulation for positive tone chemically amplified[2] http://www.ie-bas.dir.bg/Presentation.htm

resists in electron beam lithography”, Annual Report[3] http://www.ie-bas.dir.bg/Awards.htm#award1

2007, Institute of electronics, BAS, ed. N.Gerassimov,[4] http://www.ceec.fnts.bg/e-plus-e/Abstracts-2013-3-4.

Ch.Gelev, (2008), 81-89.

pdf

19. T.Tanaka, K.Vutova, E.Koleva, G.Mladenov,[5] K.Vutova, G.Mladenov, T.Tanaka,“Photoelectron

I.Koyama,“Room temperature PBII sterilization of

signal simulation at surface analysis”, Chapter in amaterials”, accepted for presentation on the Sevenths p e c i a l r e v i e w b o o k “P r a c t i c a l A s p e c t s a n d

International Symposium on Polymer Surface

Applications of Electron Beam Irradiation ”, еds.:

Modiﬁcation, July 12-15, 2009, University of Maine,

M.Nemtanu, M.Brasoveanu, publ. Research Signpost/

Orono, Maine, USA.

Transworld Research Network, 235-254, (2011).

20. K.Vutova, G.Mladenov, E.Koleva, I.Kostic, T.Tanaka,― 114 ―