研究者詳細 - 石川　健治

Towards prevention and prediction of infectious diseases with virus sterilization using ultraviolet light and low-temperature plasma and bio-sensing devices for health and hygiene care 査読有り国際共著 Open Access

Kumagai, S; Nishigori, C; Takeuchi, T; Bruggeman, P; Takashima, K; Takahashi, H; Kaneko, T; Choi, EH; Nakazato, K; Kambara, M; Ishikawa, K

JAPANESE JOURNAL OF APPLIED PHYSICS 61 巻 ( SA ) 頁： SA0808 2022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：Japanese Journal of Applied Physics

Inspired by the ideas of many authors, we provide insight on state-of-the-art potential technologies for the prevention and prediction of infectious diseases before they spread. This review also surveys virus sterilization with ultraviolet light and low temperature plasma technologies. Researchers in the various fields of medicine, materials, electronics, and plasma sciences have addressed increasingly challenging demands and the discussion encompasses the major challenges in societies that are faced with the threat of infectious diseases. In addition, technologies that use nanomaterials are evaluated for infection prevention and hygiene purposes. Advances in biomedical diagnostics for health care in terms of complementary metal-oxide-semiconductor transistors-based devices and telemetry for health monitoring are also reviewed.

DOI： 10.35848/1347-4065/ac1c3d

Perspectives on functional nitrogen science and plasma-based in situ functionalization 査読有り Open Access

Ishikawa, K

JAPANESE JOURNAL OF APPLIED PHYSICS 61 巻 ( SA ) 頁： SA0802 2022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：Japanese Journal of Applied Physics

Reactive nitrogen species (RNS) generated by controlled electron impacts in conjunction with the use of dinitrogen can react with oxygen and/or hydrogen to generate highly reactive compounds. The related field of functional nitrogen science provides new opportunities for nitrogen utilization based on non-equilibrium plasma processing. This revolutionary technique permits plasma-based nitrogen fixation at the locations at which materials such as dopants and fertilizers are required. This system, based on the in situ generation of RNS at the point of use, is expected to replace conventional processes involving nitrogen cycles employing ammonia and nitric acid. Optimization of this new approach will require nitrogen doping to be tuned by atomic-scale localization of nitrogen. This review discusses the applications of functional nitrogen and the processes by which functionalization in both inorganic materials and living organisms can occur when using RNS.

DOI： 10.35848/1347-4065/ac3558

Functional nitrogen science based on plasma processing: quantum devices, photocatalysts and activation of plant defense and immune systems 査読有り国際共著 Open Access

Kaneko, T; Kato, H; Yamada, H; Yamamoto, M; Yoshida, T; Attri, P; Koga, K; Murakami, T; Kuchitsu, K; Ando, S; Nishikawa, Y; Tomita, K; Ono, R; Ito, T; Ito, AM; Eriguchi, K; Nozaki, T; Tsutsumi, T; Ishikawa, K

JAPANESE JOURNAL OF APPLIED PHYSICS 61 巻 ( SA ) 頁： SA0805 2022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：Japanese Journal of Applied Physics

Nitrogen is a very common element, comprising approximately 78% of Earth's atmosphere, and is an important component of various electronic devices while also being essential for life. However, it is challenging to directly utilize dinitrogen because of the highly stable triple bond in this molecule. The present review examines the use of non-equilibrium plasmas to generate controlled electron impacts as a means of generating reactive nitrogen species (RNS) with high internal energy values and extremely short lifetimes. These species include ground state nitrogen atoms, excited nitrogen atoms, etc. RNS can subsequently react with oxygen and/or hydrogen to generate new highly reactive compounds and can also be used to control various cell functions and create new functional materials. Herein, plasma-processing methods intended to provide RNS serving as short-lived precursors for a range of applications are examined in detail.

DOI： 10.35848/1347-4065/ac25dc

Wide range applications of process plasma diagnostics using vacuum ultraviolet absorption spectroscopy 査読有り

Takeda, K; Ishikawa, K; Hori, M

REVIEWS OF MODERN PLASMA PHYSICS 6 巻 ( 1 ) 2022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：Reviews of Modern Plasma Physics

Applications of plasma diagnostics using vacuum ultraviolet absorption spectroscopy (VUVAS) in our studies are summarized in this article. The plasma diagnostics with absorption spectroscopy is a powerful tool for investigating behaviors of reactive species in plasma processes, because it enables us to measure the absolute density. In our group, we have focused on the clarification of reaction mechanisms of atomic species in the plasma processes, and the behaviors of atomic species generated in various process plasmas have been investigated using the VUVAS with a plasma light source. Using the VUVAS, we can investigate not only the absolute density but also surface reactions of atomic species in the plasma processes. On the other hand, in our group, the real-time monitoring of atomic species based on VUVAS has been realized in the plasma processes, and the effects of the initial state of reactor wall surface on the behaviors of atomic species in a process plasma have been quantitatively investigated. Moreover, the VUVAS has been applied to the measurements of reactive species generated by atmospheric pressure plasmas which attracts much attention because of its applications to the bio and medical research fields. These results and experimental technique used in our studies are extremely useful for the further developments of plasma processes such as etching, deposition, surface modification, bio-medical applications and so on in the future.

DOI： 10.1007/s41614-022-00075-3

Plasma Diagnostics and Characteristics of Hydrofluorocarbon Films in Capacitively Coupled CF4/H2Plasmas 査読有り

Hsiao S.N., Imai Y., Britrun N., Tsutsumi T., Ishikawa K., Sekine M., Hori M.

IEEE International Symposium on Semiconductor Manufacturing Conference Proceedings 2022-December 巻 2022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：IEEE International Symposium on Semiconductor Manufacturing Conference Proceedings

Plasma diagnostics including electron density, temperature, neutral atomic densities of the CH4H2 plasmas were performed in a capacitively-coupled reactor using surface-wave probe, Langmuir probe and vacuum ultraviolet absorption spectroscopy. The plasma density increased monotonically with varying H2 content from 30 to 90 %. The electron temperature first decreased with H2 up to 50 % and then increased at higher H2 concentration. The HF concentration reached a maximum value at a H2 of approximately 50 %, which is probably due to balance between H and F radicals from the plasma. Increasing the H2 content resulted in a higher H concentration and a less cross-linked structure of the amorphous hydrofluorocarbon films, analyzed by using in situ Fourier transformation infrared spectroscopy.

DOI： 10.1109/ISSM55802.2022.10027112

On the Etching Mechanism of Highly Hydrogenated SiN Films by CF4/D2 Plasma: Comparison with CF4/H2 査読有り Open Access

Hsiao, SN; Nguyen, TTN; Tsutsumi, T; Ishikawa, K; Sekine, M; Hori, M

COATINGS 11 巻 ( 12 ) 頁： 1535 2021年12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：Coatings

With the increasing interest in dry etching of silicon nitride, utilization of hydrogencontained fluorocarbon plasma has become one of the most important processes in manufacturing advanced semiconductor devices. The correlation between hydrogen-contained molecules from the plasmas and hydrogen atoms inside the SiN plays a crucial role in etching behavior. In this work, the influences of plasmas (CF<inf>4</inf>/D<inf>2</inf> and CF<inf>4</inf>/H<inf>2</inf> ) and substrate temperature (T<inf>s</inf>, from −20 to 50◦ C) on etch rates (ERs) of the PECVD SiN films were investigated. The etch rate performed by CF<inf>4</inf>/D<inf>2</inf> plasma was higher than one obtained by CF<inf>4</inf>/H<inf>2</inf> plasma at substrate temperature of 20◦ C and higher. The optical emission spectra showed that the intensities of the fluorocarbon (FC), F, and Balmer emissions were stronger in the CF<inf>4</inf>/D<inf>2</inf> plasma in comparison with CF<inf>4</inf>/H<inf>2</inf> . From X-ray photoelectron spectra, a thinner FC layer with a lower F/C ratio was found in the surface of the sample etched by the CF<inf>4</inf>/H<inf>2</inf> plasma. The plasma density, gas phase concentration and FC thickness were not responsible for the higher etch rate in the CF<inf>4</inf>/D<inf>2</inf> plasma. The abstraction of H inside the SiN films by deuterium and, in turn, hydrogen dissociation from Si or N molecules, supported by the results of in situ monitoring of surface structure using attenuated total reflectance-Fourier transform infrared spectroscopy, resulted in the enhanced ER in the CF<inf>4</inf>/D<inf>2</inf> plasma case. The findings imply that the hydrogen dissociation plays an important role in the etching of PECVD-prepared SiN films when the hydrogen concentration of SiN is higher. For the films etched with the CF<inf>4</inf>/H<inf>2</inf> at −20◦ C, the increase in ER was attributed to a thinner FC layer and surface reactions. On the contrary, in the CF<inf>4</inf>/D<inf>2</inf> case the dependence of ER on substrate temperature was the consequence of the factors which include the FC layer thickness (diffusion length) and the atomic mobility of the etchants (thermal activation reaction).

DOI： 10.3390/coatings11121535

Effects of hydrogen content in films on the etching of LPCVD and PECVD SiN films using CF4/H2 plasma at different substrate temperatures 査読有り

プラズマがん治療招待有り査読有り

石川健治，堀勝

静電気学会誌 45 巻 ( 6 ) 頁： 206 - 212 2021年11月

Hsiao, SN; Britun, N; Nguyen, TTN; Tsutsumi, T; Ishikawa, K; Sekine, M; Hori, M

PLASMA PROCESSES AND POLYMERS 18 巻 ( 11 ) 頁： 2100078 2021年11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：Plasma Processes and Polymers

The dependences of etching characteristics on substrate temperature (T<inf>s</inf>, from –20 to 50°C) of the plasma-enhanced chemical vapor deposition (PECVD) SiN films (PE-SiN) and low-pressure chemical vapor deposition (LPCVD) SiN films (LP-SiN) with CF<inf>4</inf>/H<inf>2</inf> plasma were investigated. The Fourier-transform infrared spectroscopy shows that both film types were N–H bond-rich films, but in different hydrogen contents (PE-SiN 22.7 at% and LP-SiN 3.8 at%) from the Rutherford backscattering spectroscopy analyses. A higher hydrogen content led to a thinner fluorocarbon thickness because of the reaction between hydrogen outflux and C and N to form an HCN byproduct. The etch rates (ER) for the PE-SiN were higher than that of the LP-SiN at all T<inf>s</inf>, due to the different FC thickness and etching mechanisms proposed. The formation of the N−H<inf>x</inf> layer on PE-SiN at low temperature caused the decrease in ER. For the LP-SiN, the weak dependences of T<inf>s</inf> on surface structure and ER were observed.

DOI： 10.1002/ppap.202100078

Plasma-activated Ringer's lactate solution inhibits the cellular respiratory system in HeLa cells 査読有り

Tanaka, H; Maeda, S; Nakamura, K; Hashizume, H; Ishikawa, K; Ito, M; Ohno, K; Mizuno, M; Motooka, Y; Okazaki, Y; Toyokuni, S; Kajiyama, H; Kikkawa, F; Hori, M

PLASMA PROCESSES AND POLYMERS 18 巻 ( 10 ) 頁： 2100056 2021年10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：Plasma Processes and Polymers

Nonequilibrium atmospheric pressure plasma has enabled a variety of new applications in medicine, agriculture, and other industries. It is particularly noteworthy that plasma itself and/or plasma-activated culture medium have been shown to preferentially kill various cancer cells. We have previously developed a plasma-activated Ringer's lactate solution (PAL) for use as a new cancer treatment. In this study, behaviors of extracellular and intracellular reactive oxygen and nitrogen species in the cellular respiratory system of PAL-treated HeLa cells were investigated using an extracellular flux analyzer and a probe to measure mitochondrial membrane potential. In PAL-treated HeLa cells, extracellular hydrogen peroxide in PAL was found to be responsible for the induction of intracellular hydrogen peroxide and apoptosis, while other components in PAL are responsible for the induction of non-H<inf>2</inf>O<inf>2</inf> intracellular ROS and non-apoptotic cell death, which should be clarified by further experiments. We believe that these are long-lived species derived from plasma-activated lactates. Furthermore, we found that the plasma-activated lactates inhibited glycolysis and the tricarboxylic acid (TCA) cycle, but not the electron transport chain in HeLa cells. These results suggest that PAL induces multiple modes of cell death, including apoptosis through hydrogen peroxide, and non-apoptotic cell death associated with the impairment of mitochondrial functions (glycolysis and TCA cycle). These findings shed light on the novel mechanism underlying plasma-activated lactate-induced cell death.

DOI： 10.1002/ppap.202100056

Low temperature plasma irradiation products of sodium lactate solution that induce cell death on U251SP glioblastoma cells were identified 査読有り Open Access

Tanaka, H; Hosoi, Y; Ishikawa, K; Yoshitake, J; Shibata, T; Uchida, K; Hashizume, H; Mizuno, M; Okazaki, Y; Toyokuni, S; Nakamura, K; Kajiyama, H; Kikkawa, F; Hori, M

SCIENTIFIC REPORTS 11 巻 ( 1 ) 頁： 18488 2021年9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：Scientific Reports

Low-temperature plasma is being widely used in the various fields of life science, such as medicine and agriculture. Plasma-activated solutions have been proposed as potential cancer therapeutic reagents. We previously reported that plasma-activated Ringer’s lactate solution exhibited selective cancer-killing effects, and that the plasma-treated L-sodium lactate in the solution was an anti-tumor factor; however, the components that are generated through the interactions between plasma and L-sodium lactate and the components responsible for the selective killing of cancer cells remain unidentified. In this study, we quantified several major chemical products, such as pyruvate, formate, and acetate, in plasma-activated L-sodium lactate solution by nuclear magnetic resonance analysis. We further identified novel chemical products, such as glyoxylate and 2,3-dimethyltartrate, in the solution by direct infusion-electrospray ionization with tandem mass spectrometry analysis. We found that 2,3-dimethyltartrate exhibited cytotoxic effects in glioblastoma cells, but not in normal astrocytes. These findings shed light on the identities of the components that are responsible for the selective cytotoxic effect of plasma-activated solutions on cancer cells, and provide useful data for the potential development of cancer treatments using plasma-activated L-sodium lactate solution.

DOI： 10.1038/s41598-021-98020-w

先端デバイス構造を実現する超絶ドライエッチング技術の最前線おわりに招待有り査読有り

石川健治，竹田圭吾

プラズマ核融合学会誌 97 巻 ( 9 ) 頁： 534 - 536 2021年9月

Effects of free radicals generated by atmospheric pressure plasma on physical actions and biochemical relaxations (PACR) 招待有り査読有り

石川健治, 橋爪博司, ミロンカメリア, 田中宏昌, 堀勝

放射線生物研究 56 巻 ( 3 ) 頁： 280 - 294 2021年9月

窒化物半導体プラズマエッチングにおける原子層反応制御と低ダメージプロセス招待有り査読有り

堤隆嘉，石川健治，近藤博基，関根誠，堀勝

プラズマ核融合学会誌 97 巻 ( 9 ) 頁： 517 - 521 2021年9月

先端デバイス構造を実現する超絶ドライエッチング技術の最前線はじめに招待有り査読有り

石川健治，竹田圭吾

プラズマ核融合学会誌 97 巻 ( 9 ) 頁： 508 - 510 2021年9月

Novel Method of Rebound Tailing Pulse (RTP) for Water Dissociation 査読有り

Shimizu, N; Borude, RR; Tanaka, R; Ishikawa, K; Oda, O; Hosoe, H; Ino, S; Inoue, Y; Hori, M

IEEE TRANSACTIONS ON PLASMA SCIENCE 49 巻 ( 9 ) 頁： 2893 - 2900 2021年9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：IEEE Transactions on Plasma Science

Simple low-temperature pulsed power dissociation method for high resistive liquid is proposed in this article. Active high voltage rebound tailing pulse (RTP) diodes are adopted to conventional high voltage pulse power sources. In order to explain this method, the study was performed using deionized water (DIW) (high resistive >17MΩcm) electrolysis with two immersed electrodes. The forward pulses, the full-width at half-maximum (FWHM) of 400 ns and forward voltage (7 kV) with rising-up ratio (dV/dt) of 1011 V/s, were applied to the electrodes. When a 5 kV RTP diode was simply adopted to this electrical circuit and DIW load in series, the high forward voltage pulse and continuous high reverse current were applied to this circuit. Then, H2 was generated at the anode electrode and OH radical (OH) in the water vessel. Those phenomena were apparently dependent on the anode electrode area. At the beginning of the forwarded high voltage application, the circuit behaved as capacitance load with generated ions and built up charges at the interface between DIW and the electrode. Continuous rebounded high reverse voltage and highly built-up reverse recovery charges induce avalanche breakdown of RTP diode. The rebounded electrical current was found to be collected in the circuit, accompanied by the generation of hydrogen and OH, as well as the tailing current flowing at the interface as a resistive load. In consequence, we point out that rebounded electrons injected from the surrounding water to the anode electrode interface induced the water electrolysis characteristically, according to RTP-diode inserted in the circuit.

DOI： 10.1109/TPS.2021.3102639