Dr. Kazumasa Okamoto Profile

Dr. Kazumasa Okamoto

Assistant Professor at Institute of Scientific and Industrial Research

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Publications (16)

Proceedings Article | 22 February 2021 Poster + Presentation

Effect of resist film thickness on line-and-space resist patterns on chromium nitride in electron beam lithography

Akihiro Konda, Kazumasa Okamoto, Takahiro Kozawa, Takao Tamura

Proceedings Volume 11612, 116120Y (2021) https://doi.org/10.1117/12.2584016

KEYWORDS: Chromium, Electron beam lithography, Photomasks, Silicon, Semiconducting wafers, Line width roughness, Glasses, Electron beams, Quartz, Lithography

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Proceedings Article | 20 September 2020 Presentation

Resist thickness dependence of line width roughness of chemically amplified resists used for electron beam lithography

Naoki Maeda, Akihiro Konda, Kazumasa Okamoto, Takahiro Kozawa, Takao Tamura

Proceedings Volume 11518, 115180D (2020) https://doi.org/10.1117/12.2574963

KEYWORDS: Line width roughness, Electron beam lithography, Chemically amplified resists, Photomasks, Electron beams, Scanning electron microscopy, Extreme ultraviolet lithography, Lithography, Extreme ultraviolet, Electronic components

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Proceedings Article | 23 March 2020 Presentation + Paper

Sensitivity enhancement of chemically amplified EUV resist by adding diphenyl sulfone derivatives

Kazumasa Okamoto, Shunpei Kawai, Takahiro Kozawa

Proceedings Volume 11326, 113260D (2020) https://doi.org/10.1117/12.2551865

KEYWORDS: Extreme ultraviolet, Extreme ultraviolet lithography, Electron beam lithography, Polymers, Lithography, Line width roughness, FT-IR spectroscopy, Ionization

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Proceedings Article | 23 March 2020 Presentation + Paper

Mechanism of resist heating effect in chemically amplified resist

Y. Ikari, K. Okamoto, N. Maeda, A. Konda, T. Kozawa, T. Tamura

Proceedings Volume 11326, 113260G (2020) https://doi.org/10.1117/12.2551825

KEYWORDS: Polymers, Monte Carlo methods, Absorption, Chemically amplified resists, Photomasks, Temperature metrology, Ions, Lithography, Image processing, Semiconductors

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The photo-mask in lithographic process of semiconductor device has an important role to transfer the downsized target image to the wafer. Due to the development of information society, demand for semiconductor devices has been growing. In order to increase photo-mask manufacturing throughput, the current density of electron beam (EB) has been getting higher. EB exposure increases the resist temperature on mask substrate inhomogeneous depending on its current density, shot size, writing order and etc. It is known that the resist sensitivity increases with irradiated resist temperature (heating effect). So, inhomogeneous temperature increase of resist on mask substrate disturbs precise pattern formation. However, the physical or chemical mechanism of heating effect has been still unknown. Here, we examined temperature dependence of acid generation process in chemically amplified resists (CARs). Poly(4- hydroxystyrene) (PHS) and poly(4-[(tert-butoxycarbonyl)oxy]styrene-co-4-hydroxystyrene) (PTBSHS) were used as CAR resin. Monte Carlo simulation moving thermalized electron under the electric field between polymer radical cations were performed with changing the temperature. From the simulation, it was revealed that the energy increase of thermalized electron contributes to the acid yield by 0.038 %/K. Quantification of the acid yields in resist films upon exposed to EB were performed with changing the temperature by titration method using Coumarin 6 (C6) as an acid sensitive dye. The acid yield increased by 0.14 %/K in PHS film and 0.21 %/K in PTBSHS film, respectively. Both values were higher than the simulation value (0.038 %/K). Pulse radiolysis experiment was also performed to observe deprotonation of polymer radical cations at 298 and 343 K. The decay of dimer radical cation of PTBSHS became 1.6 times faster at 343 K than that at 298 K. From the results, it is suggested that the heating effect mainly caused by the temperature dependence of deprotonation rate from the radical cations of PTBSHS.

Proceedings Article | 9 July 2015 Paper

Dynamics of radical ions of fluorinated polymer for Extreme Ultraviolet (EUV) lithography

Naoya Nomura, Kazumasa Okamoto, Hiroki Yamamoto, Takahiro Kozawa, Ryoko Fujiyoshi, Kikuo Umegaki

Proceedings Volume 9658, 96581C (2015) https://doi.org/10.1117/12.2193060

KEYWORDS: Fluorine, Extreme ultraviolet, Polymers, Chemical species, Extreme ultraviolet lithography, Absorption, Radiation effects, Lithography, Chemical reactions, Ions

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Proceedings Article | 27 March 2014 Paper

Deprotonation mechanism of ionized poly(4-hydroxystyrene)

Toshihiko Susa, Kazumasa Okamoto, Takuya Ishida, Hiroki Yamamoto, Takahiro Kozawa, Ryoko Fujiyoshi, Kikuo Umegaki

Proceedings Volume 9051, 90511O (2014) https://doi.org/10.1117/12.2045881

KEYWORDS: Absorption, Polymers, Extreme ultraviolet, Oxygen, Molecules, Lithography, Chemically amplified resists, Hydrogen, Scientific research, Electron beams

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Proceedings Article | 27 March 2014 Paper

Fluidity dependence of deprotonation kinetics of chemically amplified resist

Kazumasa Okamoto, Takuya Ishida, Hiroki Yamamoto, Takahiro Kozawa, Ryoko Fujiyoshi, Kikuo Umegaki

Proceedings Volume 9051, 90511T (2014) https://doi.org/10.1117/12.2046057

KEYWORDS: Chemically amplified resists, Absorption, Extreme ultraviolet, Lithography, Electron beams, Chromium, Ionization, Solids, Electron beam lithography, Photoresist processing

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Proceedings Article | 16 April 2011 Paper

Fundamental study on reaction mechanisms in chemically amplified extreme ultraviolet resists by using 61nm free-electron laser

Kazumasa Okamoto, Takahiro Kozawa, Takaki Hatsui, Yasuharu Tajima, Keita Oikawa, Mitsuru Nagasono, Takashi Kameshima, Tadashi Togashi, Kensuke Tono, Makina Yabashi, Hiroaki Kimura, Yasunori Senba, Haruhiko Ohashi, Takashi Sumiyoshi

Proceedings Volume 7972, 797217 (2011) https://doi.org/10.1117/12.879358

KEYWORDS: Ionization, Extreme ultraviolet, Free electron lasers, Ions, Electrons, Argon, Polymers, Protactinium, Absorption, Extreme ultraviolet lithography

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Proceedings Article | 16 April 2011 Paper

Deprotonation mechanism of poly(styrene-acrylate)-based chemically amplified resist

Y. Tajima, K. Okamoto, T. Kozawa, S. Tagawa, R. Fujiyoshi, T. Sumiyoshi

Proceedings Volume 7972, 79721N (2011) https://doi.org/10.1117/12.879362

KEYWORDS: Picosecond phenomena, Absorption, Extreme ultraviolet, Polymers, Chemically amplified resists, Lithography, Oscillators, Ionization, Polymethylmethacrylate, Semiconductors

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Proceedings Article | 30 March 2010 Paper

Dynamics of radical cation of poly(4-hydroxystyrene) generated in thin film upon exposure to electron beam

Kenichiro Natsuda, Takahiro Kozawa, Kazumasa Okamoto, Akinori Saeki, Seiichi Tagawa

Proceedings Volume 7639, 76391K (2010) https://doi.org/10.1117/12.846699

KEYWORDS: Absorption, Solids, Electron beams, Polymers, Extreme ultraviolet lithography, FT-IR spectroscopy, Absorbance, Chromium, Chemically amplified resists, Extreme ultraviolet

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Proceedings Article | 2 September 2009 Paper

Gap plasmon waveguide with a stub: structure for a wavelength selective device

Masanobu Haraguchi, Kazunori Iuchi, Hidenori Sokabe, Tatsuya Okuno, Toshihiro Okamoto, Masuo Fukui, Kazumasa Okamoto, Seiichi Tagawa

Proceedings Volume 7395, 73950U (2009) https://doi.org/10.1117/12.825789

KEYWORDS: Waveguides, Plasmons, Silver, Wave propagation, Metals, Transmittance, Numerical simulations, Plasmonics, Finite-difference time-domain method, Dielectrics

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Proceedings Article | 28 August 2008 Paper

Plasmonic waveguides with wavelength selective function

Masanobu Haraguchi, Yosuke Matsuzaki, Tatsuro Tsuzura, Toshihiro Okamoto, Masuo Fukui, Kazumasa Okamoto, Shu Seki, Seiichi Tagawa

Proceedings Volume 7033, 70330V (2008) https://doi.org/10.1117/12.794541

KEYWORDS: Waveguides, Plasmons, Transmittance, Mirrors, Resonators, Plasmonics, Plasmonic waveguides, Fabry–Perot interferometers, Metals, Dielectrics

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Proceedings Article | 26 March 2008 Paper

Dynamics of poly(4-hydroxystyrene) radical cation

Kazumasa Okamoto, Takahiro Kozawa, Seiichi Tagawa

Proceedings Volume 6923, 692329 (2008) https://doi.org/10.1117/12.772535

KEYWORDS: Absorption, Chromium, Lithography, Picosecond phenomena, Bioalcohols, Hydrogen, Electron beam lithography, Extreme ultraviolet, Absorbance, Polymers

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Proceedings Article | 26 March 2008 Paper

Acid-base equilibrium in chemically amplified resist

Kenichiro Natsuda, Takahiro Kozawa, Kazumasa Okamoto, Seiichi Tagawa

Proceedings Volume 6923, 69231A (2008) https://doi.org/10.1117/12.772165

KEYWORDS: Chemically amplified resists, Absorption, Polymers, Line edge roughness, Solids, Diffusion, Image quality, Extreme ultraviolet, Photoresist processing, Polymer thin films

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Proceedings Article | 29 March 2006 Paper

The reaction mechanism of poly[4-hydroxystyrene-co-4-(1,1,1,3,3,3-hexafluoro-2-hydroxypropyl)-styrene]

Hiroki Yamamoto, Takahiro Kozawa, Kazumasa Okamoto, Seiichi Tagawa, Tomoyuki Ando, Mitsuru Sato, Hiroji Komano

Proceedings Volume 6153, 61533O (2006) https://doi.org/10.1117/12.656262

KEYWORDS: Polymers, Absorption, Electron beams, Ionization, Chemically amplified resists, Ionizing radiation, Picosecond phenomena, Silver, X-rays, Extreme ultraviolet lithography

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Proceedings Article | 4 May 2005 Paper

Deprotonation mechanism of poly(4-hydroxystyrene) and its derivative

Atsuro Nakano, Kazumasa Okamoto, Yukio Yamamoto, Takahiro Kozawa, Seiichi Tagawa, Toshiyuki Kai, Hiroaki Nemoto, Tsutomu Shimokawa

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.596827

KEYWORDS: Phase modulation, Absorption, Polymers, Image processing, Bioalcohols, Ionizing radiation, Ionization, Electron beams, Absorbance, Chemically amplified resists

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Showing 5 of 16 publications

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