研究者詳細 - 石川　健治

論文 - 石川　健治

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Selective isotropic atomic-layer etching of thin films by using dry chemical removal tool 査読有り

Shinoda K., Miyoshi N., Kobayashi H., Izawa M., Ishikawa K., Hori M.

Proceedings of SPIE the International Society for Optical Engineering 12499 巻 2023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：Proceedings of SPIE the International Society for Optical Engineering

There has been considerable interest in the development of isotropic atomic layer etching (ALE) for the conformal removal of thin films. Material selectivity is crucial for the development of isotropic ALE because the next generation of semiconductor devices will be constructed with miniaturized 3D structures using a variety of very thin films. We developed plasma-assisted thermal-cyclic ALE, which is a repetition of surface modification by plasma exposure and removal of the modified surface by infrared heating. We developed a 300-mm tool, namely, dry chemical removal (DCR), which is equipped with an inductively coupled plasma (ICP) source and infrared lamps, to facilitate rapid thermal desorption of the modified surface. An important feature of the plasma-assisted thermal-cyclic ALE is that it has more tuning knobs than that of conventional ALE because it uses two temperatures: a low temperature for surface modification and an elevated temperature for the removal of the modified surface. This paper presents the selective ALE of various materials, i.e., Si3N4, TiN, W, and SiGe using the developed tool. The mechanisms of the selectivity are divided into two categories: formation of an ammonium salt-based modified layer and selectivity control by adjusting the infrared heating time. This paper reviews the selective ALE mechanisms, focusing on the results of in situ analysis of surface reactions, and presents some of the latest findings.

DOI： 10.1117/12.2664547

Scopus

低温大気圧プラズマによるフリーラジカル生成とその生物学的意義-放射線との比較- 査読有り

近藤隆, 田中宏昌, 石川健治, 堀勝

化学工業 74 巻 ( 2 ) 頁： 120 - 126 2023年

総説：プラズマなどで処理された水の多様性査読有り

石川健治

静電気学会誌 46 巻頁： 209 2023年

Impact of microsecond-pulsed plasma-activated water on papaya seed germination and seedling growth 査読有り

Xi, DK; Zhang, XH; Yang, SZ; Yap, SS; Ishikawa, K; Hori, M; Yap, SL

CHINESE PHYSICS B 31 巻 ( 12 ) 2022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：Chinese Physics B

The seed of Carica papaya consists of a hard shell-like testa with inhibitors in vivo causing slow, erratic and asynchronous germination. In this work, plasma-activated water prepared by microsecond-pulsed plasma jets (μPAW) was applied to treat papaya seeds. The μPAW after plasma activation of 30 min was about 40 °C. The reactive species such as NO<inf>2</inf>, NO<inf>3</inf>, and H<inf>2</inf>O<inf>2</inf> in the μPAW activated from deionized water were measured and correlated to the seed germination rate and the seedling growth performance. The μPAW-treated papaya seed achieved a higher germination rate of 90%, which is 26% higher than the control group using deionized water. Comparing the results with a hot water (40 °C) reference group showed that the reactive species in μPAW played primary roles in germination improvement, with little effect caused by the heat shock. The μPAW also sterilized the treated seeds, reducing the germination stress. The morphological change in the seeds was observed by SEM, showing an effect of physical etching after treatment promoting seed imbibition. The biochemical mechanism of the seed germination was deduced with reference to the evolution of surface chemistry, functional groups, and ABA content. The accelerated seed metabolism observed was corresponded to the chemical modification pathway. Besides, early seedlings developed from treated seeds were observed to be healthy, grow more leaves, and have better root structures. The content of MDA in the treated papaya seedlings decreased along with increased SOD and higher ion concentration. The μPAW that can be prepared at atmospheric pressure for bulk production offers a low-risk and cost-effective seed priming technology that may significantly increase the production of agricultural crops.

DOI： 10.1088/1674-1056/ac904e

Web of Science

Scopus

Indoor Floor Heel Mark Removal Using Spark Discharges and Pressurized Airflow 査読有り Open Access

Sakamoto, Y; Tsutsumi, T; Tanaka, H; Ishikawa, K; Hashizume, H; Hori, M

COATINGS 12 巻 ( 12 ) 2022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

Heel marks (HMs), which are the black stains made by shoe soles on indoor floors, can be difficult to remove. However, this study shows how spark discharges combined with pressurized airflow in 60 s discharge treatments can remove such HMs. We further show that maximizing the HM removal rates depended on the electrode gap distance because of changes in the spark discharge parameters. In our experiments, the electrical voltage waveforms are shown with voltage spikes, called spark discharges, and the spike numbers were counted in 0.6-ms time units. It was found that the number of spark discharges increases when the electrode gap distance was widened from 5 mm to 10 mm and the pressurized airflow was added, and the HM removal rates increased 11.5%, the HM removal rates could be maximized. Taken together, the results show that spark discharges combined with pressurized air can remove HMs from indoor floors without no visual damage. This paper is a preliminary report showing that HMs can be removed by plasma.

DOI： 10.3390/coatings12121938

Open Access

Web of Science

Scopus

Carbon Layer Formation on Hexagonal Boron Nitride by Plasma Processing in Hydroquinone Aqueous Solution 査読有り

Inoue, K; Sakakibara, N; Goto, T; Ito, T; Shimizu, Y; Hakuta, Y; Ishikawa, K; Hori, M; Terashima, K

ACS APPLIED MATERIALS & INTERFACES 14 巻 ( 47 ) 頁： 53413 - 53420 2022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：ACS Applied Materials and Interfaces

Although hexagonal boron nitride (hBN) is a thermally conductive and electrically insulating filler in composite materials, surface modification remains difficult, which limits its dispersibility and functionalization. In this study, carbon layer formation on hBN particles by plasma processing in hydroquinone aqueous solution was investigated as a surface modification technique. Carbon components with features of polymeric hydrogenated amorphous carbon were found to be uniformly distributed on the hydroquinone-aided plasma-modified hBN (HQpBN) particles. Electron spin resonance measurements revealed abundant unpaired electrons in HQpBN, indicating that defects were formed on hBN by plasma processing and that the carbon layer contained dangling bonds. The defects on hBN could help in the attachment of the carbon layer, whereas the dangling bonds could act as reactive sites for further functionalization. The carbon layer on HQpBN was successfully functionalized with isocyanate groups, thus confirming the ability of this carbon layer to facilitate surface modification. These results demonstrate that the carbon layer formed on hBN can provide a designable interface in organic/inorganic composite materials.

DOI： 10.1021/acsami.2c15951

Web of Science

Scopus

PubMed

Dry etching of ternary metal carbide TiAlC via surface modification using floating wire-assisted vapor plasma 査読有り Open Access

Nguyen, TTN; Shinoda, K; Hamamura, H; Maeda, K; Yokogawa, K; Izawa, M; Ishikawa, K; Hori, M

SCIENTIFIC REPORTS 12 巻 ( 1 ) 頁： 20394 2022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：Scientific Reports

Dry etching of ternary metal carbides TiAlC has been first developed by transferring from wet etching to dry etching using a floating wire (FW)-assisted Ar/ammonium hydroxide vapor plasma. FW-assisted non-halogen vapor plasma generated at medium pressure can produce high-density reactive radicals (NH, H, and OH) for TiAlC surface modifications such as hydrogenation and methylamination. A proposed mechanism for dry etching of TiAlC is considered with the formation of the volatile products from the modified layer.

DOI： 10.1038/s41598-022-24949-1

Effects of deposition precursors of hydrogenated amorphous carbon films on the plasma etching resistance based on mass spectrometer measurements and machine learning analysis 査読有り Open Access

Kurokawa, J; Kondo, H; Tsutsumi, T; Ishikawa, K; Sekine, M; Hori, M

VACUUM 205 巻 2022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：Vacuum

In the growth of hydrogenated amorphous carbon (a-C:H) films by plasma enhanced chemical vapor deposition (PECVD) with H<inf>2</inf>, CH<inf>4</inf> and C<inf>3</inf>H<inf>6</inf> plasma, the gas phase reaction of active species and their contribution to properties of deposited a-C:H film were quantitatively investigated using appearance quadrupole mass spectrometry (QMS) and machine learning. The QMS measurement indicated that two-types of neutral radicals were generated by the dissociation and polymerization of the raw material gasses. A random forest regression model was employed as a prediction model to analyze the correlation between the neutral species and etching rates by molecular oxygen (O<inf>2</inf>) plasma without any stage bias, which were measured by in-situ ellipsometry. The coefficient of determination (R2), an indicator of the degree of prediction accuracy, was 0.906 and 0.584 for the training and test data, respectively. SHapley Additive exPlanations (SHAP), interpreting the random forest model, were used to quantitatively indicate the contribution of radicals to the etching rate, including their synergistic and secondary effects. They indicated that carbon-rich radicals, such as C<inf>3</inf>H<inf>3</inf> and C<inf>5</inf>H<inf>5</inf>, contributed to a decrease in the etching rate, whereas hydrogen-rich radicals, such as CH<inf>x</inf> (x=1,2,3,4), C<inf>2</inf>H<inf>5</inf>, C<inf>4</inf>H<inf>9</inf>, and C<inf>5</inf>H<inf>9,11</inf> induced an increase in the etching rate by the O<inf>2</inf> plasma. (200 words)

DOI： 10.1016/j.vacuum.2022.111351

Web of Science

Scopus

Dissociation channels of c-C4F8 to C2F4 in reactive plasma 査読有り国際誌

Hayashi, T; Ishikawa, K; Sekine, M; Hori, M; Iwayama, H

JAPANESE JOURNAL OF APPLIED PHYSICS 61 巻 ( 10 ) 頁： 106006 2022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：Japanese Journal of Applied Physics

Progress in computational methods and personal computing has made possible more accurate estimations for primary dissociation channels and energies. The main dissociation route is revealed to be via the 7E excited state with an energy of 12.23 eV, which is composed of transitions from the highest occupied molecular orbital with b1 symmetry to some degenerate unoccupied e molecular orbitals. The main contributing e orbitals consisted of antibonding combination of C2F4 π-bonding orbitals. This degenerate 7E state is lowered by non-adiabatic transitions through the conical interactions on the dissociating route to 2C2F4, so the energy is finally relaxed at the dissociative second lowest 1E excited state leading to 2C2F4 production. In the electron attachment process, the calculated results show that the F- ion is produced from the excited states of the D4h c-C4F8- ion through conical interactions at the energies of 4.3 eV, 5.6 eV, and 5.0 eV, along the C-F dissociation route.

DOI： 10.35848/1347-4065/ac895e

Web of Science

Scopus

非平衡大気圧プラズマを用いた陸上養殖実現に向けた基礎的研究査読有り Open Access

田中宏昌, 秋山真一, 橋爪博司, 紅林佑弥, 石川健治, 堀勝

応用物理学会学術講演会講演予稿集 2022.2 巻 ( 0 ) 頁： 1741 - 1741 2022年8月

In-liquid plasma synthesis of iron-nitrogen-doped carbon nanoflakes with high catalytic activity 査読有り

Kondo, H; Hamaji, R; Amano, T; Ishikawa, K; Sekine, M; Hiramatsu, M; Hori, M

PLASMA PROCESSES AND POLYMERS 19 巻 ( 8 ) 2022年8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

Flake-shaped carbon nanomaterials with nitrogen (N) and iron (Fe) addition, so-called carbon nanoflakes (CNFLs), were synthesized by the in-liquid plasma using two different kinds of additive agents, such as hemin and iron (II) phthalocyanine (FePc). According to scanning electron microscopy images and Raman spectra, CNFLs with a size of at least 100 nm order were formed regardless of types of additive agents, and crystallinity of six-membered ring structures was improved as additive agents increased. Photoelectron spectra showed that pyridinic N contents increased from 1.05% to 2.02% with increasing FePc, while those decreased from 0.34% to 0.14% with hemin. In the oxygen reduction reaction, onset potential values also increased from 0.71 to 0.79 eV with increasing FePc, while those decreased from 0.60 to 0.47 eV with hemin. These results suggested that the catalytic activity of CNFLs was effectively improved by the increase of pyridinic N by the in-liquid plasma synthesis with FePc. In contrast, the electron transfer numbers reached 3.81 when hemin increased, although those were less than 2.88 in the cases using FePc. These results mean that the in-liquid plasma synthesis method of CNFLs using FePc has the potential to further improve its catalytic activity.

DOI： 10.1002/ppap.202100203

Web of Science

Scopus

Dry Process

Akatsuka H., Kurihara K., Toyoda H., Karahashi K., Ishikawa K., Ichiki T., Eriguchi K., Kuboi N., Matsui M., Nunomura S.

Japanese Journal of Applied Physics 61 巻 ( SI ) 2022年7月

Study of optical emission spectroscopy using modified Boltzmann plot in dual-frequency synchronized pulsed capacitively coupled discharges with DC bias at low-pressure in Ar/O2/C4F8 plasma etching process 査読有り

Sahu, BB; Nakane, K; Ishikawa, K; Sekine, M; Tsutsumi, T; Gohira, T; Ohya, Y; Ohno, N; Hori, M

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 24 巻 ( 22 ) 頁： 13883 - 13896 2022年6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：Physical Chemistry Chemical Physics

We consider the corona model and local thermal equilibrium approximations of a real plasma to measure the electron temperature (T<inf>e</inf>) and density (n<inf>e</inf>), respectively, using the optical emission spectroscopy (OES) method in dual-frequency pulsed capacitively coupled plasmas (CCPs) in a reactive mixture of Ar/O<inf>2</inf>/C<inf>4</inf>F<inf>8</inf> at a low operating pressure. The operation conditions such as DC continuous and synchronized were used for the study and plasma characterization for the intended plasma application such as high aspect ratio etching (HARE). We show that the present plasma conditions are dominated by a corona balance rather than the supremacy of multi-step excitation. This fact has enabled us to utilize the modified Boltzmann plot technique to evaluate the T<inf>e</inf> values. In the second method, we simultaneously used the Boltzmann and Saha equations to determine the n<inf>e</inf> value using the line intensity ratio and the value of T<inf>e</inf>. Time-resolved measurements of T<inf>e</inf> and n<inf>e</inf> were performed for completeness, and the insight of the pulsed discharge was investigated. Time evolution of n<inf>e</inf> and T<inf>e</inf> using the OES method revealed a similar trend in the change of plasma parameters, indicating electron impact ionization during the pulse on phase. It was seen that n<inf>e</inf> in the afterglow speedily decreased within a short time of ∼5 μs. Analysis suggests the formation of afterglow plasmas, which are composed of positive and negative ions with very low electron density. The results revealed that the DC-synchronized operation could be useful for plasma application such as HARE due to different plasma characteristics. It also suggests the production of ion-ion plasmas by the effective utilization of negative ions in the afterglow phase. The corona balance condition was validated in our experiments, and the results were compared with the existing literature.

DOI： 10.1039/d2cp00289b

Web of Science

Scopus

PubMed

Low-temperature reduction of SnO2 by floating wire-assisted medium-pressure H2/Ar plasma 査読有り

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

PLASMA PROCESSES AND POLYMERS 19 巻 ( 6 ) 2022年6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

Reduction of SnO<inf>2</inf> to form spherical Sn particles and Sn etching are obtained by floating wire (FW)-assisted medium-pressure H<inf>2</inf>/Ar plasma. High-density H<inf>2</inf>/Ar plasma (1014 cm−3) with a larger treatment area at medium pressure (10 kPa) produces a two-times higher removal rate of SnO<inf>2</inf> (0.111 mg/min) than that at atmospheric pressure with the same treatment area of 300 mm2. SnO<inf>2</inf> film is removed from the glass surface by a two-step process involving (1) reduction of SnO<inf>2</inf> by FW-H<inf>2</inf>/Ar plasma to form spherical Sn particles and (2) removal of low-contact Sn particles by water-based cleaning. High surface smoothness (roughness of 0.488 nm) and high optical transmittance (>92%) of treated samples indicate no damage compared to that of pristine quartz glass.

DOI： 10.1002/ppap.202100209

Web of Science

Scopus

Cytotoxicity of plasma-irradiated lactate solution produced under atmospheric airtight conditions and generation of the methyl amino group 査読有り Open Access

Ito, D; Iwata, N; Ishikawa, K; Nakamura, K; Hashizume, H; Miron, C; Tanaka, H; Kajiyama, H; Toyokuni, S; Mizuno, M; Hori, M

APPLIED PHYSICS EXPRESS 15 巻 ( 5 ) 2022年5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

Ringer's lactate solution was irradiated with non-equilibrium plasma under airtight conditions. The plasma-activated lactate (PAL) was produced with argon, oxygen, and nitrogen gases following purging of Ar. Cytotoxicity could be controlled by diluting PAL, and a killing effect was selectively obtained on cancer cells compared to normal cells for Ar+O2+N2 PALs. Nonetheless, cytotoxicity was partly reproduced by similar concentrations of H2O2 and NO2- in the PALs. The organics produced by plasma irradiation to lactate were investigated using nuclear magnetic resonance, and the generation of methyl amino species was confirmed.

DOI： 10.35848/1882-0786/ac6360

Open Access

Web of Science

Scopus

Plasma-assisted thermal-cyclic atomic-layer etching of tungsten and control of its selectivity to titanium nitride 査読有り

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

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B 40 巻 ( 2 ) 2022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 Vacuum Science and Technology B

Plasma-assisted thermal-cyclic atomic-layer etching (ALE) of tungsten (W), the selectivity of which with respect to TiN can be tuned between highly selective and nonselective by changing infrared-heating time, has been demonstrated. It is a two-step process consisting of exposure to radicals generated in a CHF3/O2 or CH2F2/O2/Ar plasma followed by infrared heating. Analysis by in situ x-ray photoelectron spectroscopy confirmed that a WFx-based modified surface formed on the surface of a W film exposed to radicals at -22 °C. The modified surface on the W film is volatile at a heating temperature lower than that required for removing the modified surface on the TiN film. Cyclic etching of both W and TiN was performed by using the CH2F2/O2/Ar plasma and infrared heating in a 300-mm ALE apparatus. When the infrared-heating time was not long enough to remove the modified surface on TiN, the cyclic repetition etched only the W film. On the other hand, when the infrared-heating time was long enough to remove modified surfaces on both W and TiN, the cyclic repetition etched both W and TiN films. Therefore, both highly selective and nonselective ALEs for W and TiN were obtained by choosing an optimum infrared-heating time. This shows that material selectivity in plasma-assisted thermal-cyclic ALE can be controlled by changing the infrared-heating time.

DOI： 10.1116/6.0001660

Web of Science

Scopus

稲穂への低温プラズマ照射がもたらす酒造品種玄米の品質向上査読有り

橋爪博司, 北野英己, 水野寛子, 蕭世男, 三田薫, 阿部明子, 東野里江, 松本省吾, 水野正明, 石川健治, 堀勝, 田中宏昌, 前島正義, 榊原均, 湯浅元気, 仁川進

応用物理学会学術講演会講演予稿集 2022.1 巻 ( 0 ) 頁： 1515 - 1515 2022年2月

Ar/F2プラズマとBCl3の交互供給によるAlGaN原子層エッチングでの組成比制御査読有り

中村昭平, 木村貴弘, 谷出敦, 灘原壮一, 小田修, 堀勝, 石川健治

応用物理学会学術講演会講演予稿集 2022.1 巻 ( 0 ) 頁： 1445 - 1445 2022年2月

C4F8/SF6ガス変調サイクルにおいてバイアス印加位相がエッチング形状に及ぼす影響査読有り

吉江泰斗, 堤隆嘉, 石川健治, 関根誠, 近藤博基, 堀勝

応用物理学会学術講演会講演予稿集 2022.1 巻 ( 0 ) 頁： 1447 - 1447 2022年2月

Scaffolds with isolated carbon nanowalls promote osteogenic differentiation through Runt-related transcription factor 2 and osteocalcin gene expression of osteoblast-like cells 査読有り Open Access

Ichikawa, T; Ishikawa, K; Tanaka, H; Shimizu, N; Hori, M

AIP ADVANCES 12 巻 ( 2 ) 2022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：Aip Advances

Carbon nanowalls (CNWs) with average wall-to-wall distances ranging from 100 to 3300 nm were synthesized using a radical injection plasma-enhanced chemical vapor deposition system. Application of a negative high voltage to the growth substrate using an inductor energy storage (IES) circuit provided CNWs with wall-to-wall distances depending on the nano-second pulse voltage of the IES circuit. Sparse isolated CNWs with average wall-to-wall distances of 700 nm were used for culturing Saos-2 cells. These cells showed better adhesion than the control after 2 days’ incubation and enhanced gene expression of the osteogenic differentiation genes Runt-related transcription factor 2 (Runx2) and osteocalcin after 10 days’ incubation. Sparse isolated CNW scaffolds hold promise for regulating the differentiation of osteoblast-like cells.

DOI： 10.1063/5.0075530

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論文 - 石川 健治

<石川　健治>

論文 - 石川　健治