研究者詳細 - 石川　健治

論文 - 石川　健治

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Spatial profiles of interelectrode electron density in direct current superposed dual-frequency capacitively coupled plasmas 査読有り Open Access

Ohya, Y; Ishikawa, K; Komuro, T; Yamaguchi, T; Takeda, K; Kondo, H; Sekine, M; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 15 ) 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D Applied Physics

We present experimentally determined spatial profiles of the interelectrode electron density (n <inf>e</inf>) in dual-frequency capacitively coupled plasmas in which the negative direct current (dc) bias voltage (V <inf>dc</inf>) is superposed; in the experiment, 13 MHz (P <inf>low</inf>) was applied to the lower electrode and 60 MHz (P <inf>high</inf>) to the upper electrode. The bulk n <inf>e</inf> increased substantially with increases in the external power, P <inf>high</inf>, P <inf>low</inf>, and with increases in V <inf>dc</inf>. When P <inf>low</inf> was insufficient, the bulk n <inf>e</inf> decreased as the V <inf>dc</inf> bias increased. The bulk n <inf>e</inf> increased due to its dependence on V <inf>dc</inf>, especially for |V <inf>dc</inf>| > 500 V. This may correspond to the sheath voltages (V <inf>s</inf>) of the lower electrode. The n <inf>e</inf> values in front of the upper electrode were coupled with the V <inf>dc</inf>: the V <inf>dc</inf> dependence first decreased and then increased. The dc currents (I <inf>dc</inf>) of the upper electrode were collected when a large P <inf>low</inf> was applied. The value of I <inf>dc</inf> at the threshold value of V <inf>dc</inf> ≈ V <inf>s</inf> (e.g. -500 V) increased with an increase in n <inf>e</inf>. When |V <inf>dc</inf>| exceeded the threshold, the spatial n <inf>e</inf> profile and the I <inf>dc</inf> dependence were changed relative to the electrical characteristics of the dc superposition; this led to a change in the location of the maximum n <inf>e</inf>, the width of the area of n <inf>e</inf> depletion in front of the electrodes, and a transition in the electron heating modes.

DOI： 10.1088/1361-6463/aa60f7

Open Access

Web of Science

Scopus

Behavior of absolute densities of atomic oxygen in the gas phase near an object surface in an AC-excited atmospheric pressure He plasma jet 査読有り Open Access

Takeda, K; Kumakura, T; Ishikawa, K; Tanaka, H; Sekine, M; Hori, M

APPLIED PHYSICS EXPRESS 10 巻 ( 3 ) 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

The quantitative behavior of atomic oxygen in the gas phase near a Cu wire surface in an AC-excited atmospheric pressure He plasma jet in open air was measured using time-resolved vacuum ultraviolet absorption spectroscopy. The atomic oxygen density had a peak at a distance between the plasma source and the Cu wire, and the peak position moved away from the source with an increase in the gas flow rate. The behavior is considered to be dependent on the plasma density and the influence of ambient air. The results are important for supplying atomic oxygen to samples for plasma jet treatment in the atmosphere.

DOI： 10.7567/APEX.10.036201

Open Access

Web of Science

Scopus

Characteristics of optical emissions of arc plasma processing for high-rate synthesis of highly crystalline single-walled carbon nanotubes 査読有り

Ando, A; Takeda, K; Ohta, T; Ito, M; Hiramatsu, M; Ishikawa, K; Kondo, H; Sekine, M; Suzuki, T; Inoue, S; Ando, Y; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 3 ) 2017年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Single-walled carbon nanotubes (SWNTs) were synthesized with a high growth rate using an arc plasma employing carbon electrodes with a Ni-Y mixture catalyst. However, the mechanism of growth of highly crystalline SWNTs has not been clarified. Reactions between carbon and catalyst are considered to be one of the crucial factors in SWNT growth. Optical emission spectroscopy (OES) provides the information about the species in the plasma. C2, Ni, and Y emissions in the arc plasma at different currents were measured to investigate the relationship between active species in the arc plasma and the SWNTsynthesis. On the basis of OES results, it was found that the balance between catalytic metal atoms and C2 radical emissions indicated the crystallinity ratio of SWNTs in thin graphitic or amorphous carbon layers. These results are useful for controlling the growth of SWNTs employing arc plasmas.

DOI： 10.7567/JJAP.56.035101

Web of Science

Scopus

Investigation of effects of ion energies on both plasma-induced damage and surface morphologies and optimization of high-temperature Cl2 plasma etching of GaN 査読有り

Liu, ZC; Pan, JL; Asano, A; Ishikawa, K; Takeda, K; Kondo, H; Oda, O; Sekine, M; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 2 ) 2017年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

The minimization of plasma-induced damage (PID) in plasma etching is important for the precise and smooth removal of a depth of approximately 7 nm of GaN films to fabricate gate-recess GaN-based normally-off power electronic devices. We have systematically studied the photoluminescence (PL) properties and surface morphologies of GaN films exposed to Cl<inf>2</inf> plasma at 400°C, focusing on their dependences on etch time and ion energy. It is noticeable that PL degradation saturated at etch times of more than 2 min, while surface roughness increased continuously with etch time. Variations of surface roughness with bias voltage were negligible. PID was successfully suppressed by reducing bias voltage, leading to the decrease in incident ion energy on the surface, and thus the near-band-edge emission (NBE) intensity as a PL property was increased to 98.8% of the initial value.

DOI： 10.7567/JJAP.56.026502

Web of Science

Scopus

Absolute density of precursor SiH3 radicals and H atoms in H2-diluted SiH4 gas plasma for deposition of microcrystalline silicon films 査読有り Open Access

Abe, Y; Ishikawa, K; Takeda, K; Tsutsumi, T; Fukushima, A; Kondo, H; Sekine, M; Hori, M

APPLIED PHYSICS LETTERS 110 巻 ( 4 ) 2017年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Letters

Microcrystalline hydrogenated silicon films were produced at a high deposition rate of about 2 nm/s by using a capacitively coupled plasma under a practical pressure of around 1 kPa. The SiH<inf>4</inf> source gas was almost fully dissociated when highly diluted with H<inf>2</inf> gas, and the dominant species in the gas phase were found to be SiH<inf>3</inf> radicals, which are film-growth precursors, and H atoms. The absolute density of these species was measured as the partial pressure of SiH<inf>4</inf> gas was varied. With the increasing SiH<inf>4</inf> gas flow rate, the SiH<inf>3</inf> radical density, which was on the order of 1012 cm-3, increased linearly, while the H-atom density remained constant at about 1012 cm-3. The film growth mechanism was described in terms of precursors, based on the measured flux of SiH<inf>3</inf> radicals and H atoms, and the relative fraction of higher-order radicals.

DOI： 10.1063/1.4974821

Open Access

Web of Science

Scopus

Thermally enhanced formation of photon-induced damage on GaN films in Cl2 plasma 査読有り

Liu Z., Asano A., Imamura M., Ishikawa K., Takeda K., Kondo H., Oda O., Sekine M., Hori M.

Japanese Journal of Applied Physics 56 巻 ( 9 ) 2017年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Deep ultraviolet (UV) photons emitted from Cl<inf>2</inf> plasmas become a critical cause of degradation in both photoluminescence (PL) properties and surface stoichiometry as a result of plasma-induced damage on GaN films in Cl<inf>2</inf> plasma etching at high temperatures. The damages were formed thermally by photon-irradiations of plasma UV emissions with wavelengths of >258-306 nm from Cl<inf>2</inf> plasma at temperatures greater than 500 °C. The damage were observed with a depth of approximately 3.2 nm. The PL property degraded by the UV emission-induced damage at an early period of plasma etching and reached a constant value.

DOI： 10.7567/JJAP.56.096501

Scopus

Thermal Cyclic Atomic-Level Etching of Nitride Films: A Novel Way for Atomic-Scale Nanofabrication 査読有り

Shinoda, K; Miyoshi, N; Kobayashi, H; Kurihara, M; Izawa, M; Ishikawa, K; Hori, M

ATOMIC LAYER DEPOSITION APPLICATIONS 13 80 巻 ( 3 ) 頁： 3 - 14 2017年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Ecs Transactions

A highly selective, rapid thermal-cyclic atomic-level etching (ALE) process for SiNx films has been developed. The first step of this process is exposing SiNx to hydrofluorocarbon plasma to form an (NH<inf>4</inf>)<inf>2</inf>SiF<inf>6</inf> layer on the SiNx surface. The second step is rapid thermal annealing with infrared (IR) irradiation to decompose and sublimate the (NH<inf>4</inf>)<inf>2</inf>SiF<inf>6</inf> layer. Etching of SiNx was observed after the (NH<inf>4</inf>)<inf>2</inf>SiF<inf>6</inf> layer was removed by thermal annealing. Cyclic etching tests were carried out by repeated plasma exposure and IR irradiation. It was found that the cyclic process is self-limiting because etching depth depends only on the cycle number and not on the plasma exposure time. A high selectivity over SiC<inf>2</inf> and poly Si was confirmed. This paper reviews the novel isotropic ALE for nitride films focusing on the surface reaction mechanism investigated by x-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). Isotropic ALE of TiN was also demonstrated using the same approach.

DOI： 10.1149/08003.0003ecst

Web of Science

Scopus

Microfluidic transport through micro-sized holes treated by non-equilibrium atmospheric-pressure plasma 査読有り Open Access

Takumi Ito, Kenji Ishikawa, Daisuke Onoshima, Naoto Kihara, Kentaro Tatsukoshi, Hidefumi Odaka, Hiroshi Hashizume, Hiromasa Tanaka, Hiroshi Yukawa, Keigo Takeda, Hiroki Kondo, Makoto Sekine, Yoshinobu Baba, and Masaru Hori

IEEE Transactions on Plasma Science 44 巻 ( 12 ) 頁： 3060 - 3065 2016年12月

Non-thermal atmospheric pressure plasma activates lactate in Ringer’s solution for anti-tumor effects 査読有り Open Access

Hiromasa Tanaka, Kae Nakamura, Masaaki Mizuno, Kenji Ishikawa, Keigo Takeda, Hiroaki Kajiyama, Fumi Utsumi, Fumitaka Kikkawa, and Masaru Hori

Scientific Reports 6 巻頁： 36282 2016年11月

Effects of assisted magnetic field to an atmospheric-pressure plasma jet on radical generation at the plasma-surface interface and bactericidal function 査読有り

Chih-Tung Liu, Takumi Kumakura, Kenji Ishikawa, Hiroshi Hashizume, Keigo Takeda, Masafumi Ito, Jong-Shinn Wu, and Masaru Hori

Plasma Sources Science and Technology 25 巻 ( 6 ) 頁： 065005 2016年10月

Micro sand timer in glass membrane device separates single circulating tumor cells in blood 査読有り

Daiki Kuboyama, Daisuke Onoshima, Hiroshi Yukawa, Hiromasa Tanaka, Kenji Ishikawa, Masaru Hori, and Yoshinobu Baba

The 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, Micro Total Analysis Systems 2016 (Convention Center Dublin, Dublin, Ireland, Oct. 9-13, 2016) 頁： 297 - 298 2016年10月

Control of Internal Plasma Parameters Toward Atomic Level Processing 査読有り

Makoto Sekine, Takayoshi Tsutsumi, Yusuke Fukunaga, Keigo Takeda, Hiroki Kondoa, Kenji Ishikawa, and Masaru Hori

ECS Transactions 75 巻 ( 6 ) 頁： 21 - 24 2016年10月

Thermal cyclic etching of silicon nitride by formation and desorption of ammonium fluorosilicate 査読有り

Kazunori Shinoda, Masaru Izawa, Tadamitsu Kanekiyo, Kenji Ishikawa, and Masaru Hori

Applied Physics Express 9 巻 ( 10 ) 頁： 106201 2016年9月

Cold plasma interactions with enzymes in foods and model systems 査読有り国際共著

N. N. Misra, S. K. Pankaj, Annalisa Segat, and Kenji Ishikawa

Trends in Food Science & Technology 55 巻頁： 39 - 47 2016年9月

Synthesis of calcium oxalate crystals in culture medium irradiated with non-equilibrium atmospheric-pressure plasma 査読有り

Naoyuki Kurake, Hiromasa Tanaka, Kenji Ishikawa, Kae Nakamura, Hiroaki Kajiyama, Fumitaka Kikkawa, Masaaki Mizuno, Yoko Yamanishi, and Masaru Hori

Applied Physics Express 9 巻 ( 9 ) 頁： 096201 2016年8月

Rapid electron density decay observed by surface-wave probe in afterglow of pulsed fluorocarbon-based plasma 査読有り

Yoshinobu Ohya, Manabu Iwata, Kenji Ishikawa, Makoto Sekine, Masaru Hori, and Hideo Sugai

Japanese Journal of Applied Physics 55 巻 ( 8 ) 頁： 080309 2016年7月

ラジカル支援原子層制御ナノプロセス招待有り査読有り

石川健治, 小林明子, 盧翌, 竹田圭吾, 近藤博基, 関根誠, 堀勝

化学工学 2016年7月

Primary dissociation channels of SiH4 and H abstract reactions 査読有り Open Access

Toshio Hayashi, Kenji Ishikawa, Makoto Sekine, and Masaru Hori

Japanese Journal of Applied Physics 55 巻 ( 7S2 ) 頁： 07LD07 2016年6月

Helium based cold atmospheric plasma-induced reactive oxygen species-mediated apoptotic pathway attenuated by platinum nanoparticles 査読有り Open Access

Paras Jawaid, Mati Ur Rehman, Qing-Li Zhao, Keigo Takeda, Kenji Ishikawa, Masaru Hori, Tadamichi Shimizu, and Takashi Kondo

Journal of Cellular and Molecular Medicin 20 巻 ( 9 ) 頁： 1737 - 1748 2016年6月

Formation of a SiOF reaction intermixing layer on SiO2 etching using C4F6/O2/Ar plasmas 査読有り

Yoshinobu Ohya, Maju Tomura, Kenji Ishikawa, Makoto Sekine, and Masaru Hori

Journal of Vacuum Science and Technology A Letters 34 巻 ( 4 ) 頁： 040602 2016年5月

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