研究者詳細 - 青木学聡

論文 - 青木学聡

分割表示 173 件中 121 - 140 件目／全件表示 >>

Surface oxidation of Si assisted by irradiation with large gas cluster ion beam in an oxygen atmosphere 査読有り

Ichiki, K; Ninomiya, S; Seki, T; Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 256 巻 ( 1 ) 頁： 350 - 353 2007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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Surface oxidation of Si assisted by Ar cluster impact with a current density of a few μA/cm2 under O2 atmosphere was investigated. Thin-film formation by cluster ion beam presents a number of advantages such as atomic-scale surface smoothing, high density and precise stoichiometry. We used an Ar cluster ion beam with 20 keV and a mean size of 1000 atoms per cluster and measured the emission yields of Si+ and SiO+ after Ar cluster ion irradiation in O2 atmosphere using a quadrupole mass spectrometer to investigate the dependence of Si surface oxidation on oxygen partial pressure. It was found that the Si surface was oxidized by Ar cluster ion irradiation in O2 atmosphere. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2006.12.026

Molecular dynamics study of surface modification with a glancing angle gas cluster ion beam 査読有り

Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 255 巻 ( 1 ) 頁： 265 - 268 2007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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

The collisional process of glancing angle gas cluster ion impact was studied using molecular dynamics (MD) simulations. Ar2000 clusters accelerated to 20 keV were irradiated onto a Si(1 0 0) target at various incident angles ranging from 0° to 80°. The investigation of the surface profile after collision revealed that there is a certain incident angle where the incident cluster penetrates the target surface to cause crater-like damage. For larger incident angles, such as 80° from the surface normal, the cluster slides on the target surface without creating displacements. This mechanism of non-damage irradiation was examined with respect to the perpendicular component of incident energy. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2006.11.071

The effect of incident cluster ion size on secondary ion yields produced from Si 査読有り

Satoshi Ninomiya, Kazuya Ichiki, Yoshihiko Nakata, Toshio Seki, Takaaki Aoki, Jiro Matsuo

TRANSACTIONS OF THE MATERIALS RESEARCH SOCIETY OF JAPAN, VOL 32, NO 4 32 巻 ( 4 ) 頁： 895 - 898 2007年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：MATERIALS RESEARCH SOCIETY JAPAN-MRS-J

Secondary ions emitted from a Si target have been investigated under large Ar cluster ion bombardment. Incident ion beams with energies from 10 to 30 keV were used and the mean size of the Ar cluster ion beam was about 1000 atoms per cluster. Secondary Si(n)(+)(n=1-11) ions were measured from Si under Ar cluster ion bombardment, while only atomic ions were measured under Ar monomer ion bombardment. In this study, we Succeeded to accurately measure the incident size dependence of secondary ion spectra for Si under large Ar cluster ion bombardment using a time-of-flight technique combined a primary-ion beam deflector and a secondary-ion deflector. When the total incident ion energy was kept constant, the yields of secondary cluster ions such as Si(6)(+) relative to those of Si(+) increased with size. On the other hand, when the incident Ar cluster size was kept constant, the yields of secondary cluster ions relative to those of Si(+) decreased with energy. The effect of incident cluster size on secondary ion yields is discussed.

High-intensity Si cluster ion emission from a silicon target bombarded with large Ar cluster ions 査読有り

Ninomiya, S; Aoki, T; Seki, T; Matsuo, J

APPLIED SURFACE SCIENCE 252 巻 ( 19 ) 頁： 6550 - 6553 2006年7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 Surface Science

Secondary ions emitted from Si targets were measured with a quadrupole mass spectrometer under large Ar cluster and monomer ion bombardment. Incident ion beams with energies from 7.5 to 25 keV were used and the mean size of the Ar cluster ion was about 1000 atoms/cluster. Si n+ ions with n values up to n = 8 were detected under Ar cluster ion bombardment, whereas Si cluster ions were scarcely detected under Ar monomer ion bombardment. These cluster ion yields showed the power law dependence on the cluster size. © 2006.

DOI： 10.1016/j.apsusc.2006.02.100

Molecular dynamics study of particle emission by reactive cluster ion impact 査読有り

Aoki, T; Matsuo, J

APPLIED SURFACE SCIENCE 252 巻 ( 19 ) 頁： 6466 - 6469 2006年7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 Surface Science

Molecular dynamics (MD) simulations of sputtering process with fluorine cluster impact onto silicon targets were performed. By iterating collisional simulations on a same target, accumulation of incident atoms and evolution of surface morphology were examined as well as emission process of precursors. When (F 2 ) 300 clusters were sequentially irradiated on Si(1 0 0) target at 6 keV of total incident energy, column-like surface structure covered with F atoms was formed. As the number of incident clusters increased, sputtering yield of Si atoms also increased because the target surface was well fluoridised to provide SiF x precursors. Size distribution of emitted particles showed that SiF 2 was the major sputtered particle, but various types of silicon-fluoride compounds such like Si 2 F x , Si 3 F x and very large molecules consists of 100 atoms were also observed. This size distribution and kinetic energy distribution of desorbed materials were studied, which showed that the sputtering mechanism with reactive cluster ions is similar to that under thermal equilibrium condition at high-temperature. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2006.02.195

Secondary ion measurements for oxygen cluster ion SIMS 査読有り

Ninomiya, S; Aoki, T; Seki, T; Matsuo, J

APPLIED SURFACE SCIENCE 252 巻 ( 19 ) 頁： 7290 - 7292 2006年7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 Surface Science

We have proposed to use oxygen cluster ions, which are much larger than molecular ions, as primary ions for secondary ion mass spectrometry (SIMS). A high intensity gas cluster ion source with a current density of a few μAs/cm 2 has been developed. Secondary ions emitted from Si have been investigated under O 2 and Ar cluster ion bombardment. A large enhancement of the yield of secondary ions produced by large O 2 and Ar cluster ions was found. The SIMS system utilizing large O 2 cluster ions must give both excellent depth resolution and high secondary ion yield. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2006.02.138

Molecular dynamics simulations of the cluster-size effect on the sputtering process with reactive gas cluster ions 査読有り

Aoki T., Matsuo J.

Materials Research Society Symposium Proceedings 908 巻頁： 18 - 24 2006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：Materials Research Society Symposium Proceedings

To investigate the size-effect of reactive clusters on sputtering processes, we performed molecular dynamics (MD) simulations of reactive cluster ions with various sizes impacting on solid targets. Various sizes of fluorine clusters, (F2)30, (F2)300 and (F 2)3000, were irradiated on a Si(100) target at the same total incident energy of 6 keV. These clusters were irradiated on the same target one after another in order to reproduce real experimental conditions such as the accumulation of fluorine atoms in the target. The MD simulations of sequential cluster impacts enabled to perform various statistical analyses regarding the sputtered particles. The study of cluster size distributions showed that the sputtering process by reactive cluster ion impact has similarity with the emission from quasi-liquid materials excited to hyper-thermal conditions by ion bombardment. However, the major sputtered particles were different with each other; Si for (F2)30 (100 eV/atom), SiF2 for (F2)300 (10 eV/atom), and SiF 3 for (F2)3000 (1 eV/atom). At the impact of a large size cluster with low incident energy, a large number of Si-F bondings were generated at the cluster-target interface surface, which enhances formation of volatile SiFx compounds with many fluorine atoms. In contrast, a small cluster with high kinetic energy-per-atom could cause the formation of numerous energetic surface atoms at the near surface region, which could be sputtered without being well fluoridated. © 2006 Materials Research Society.

DOI： 10.1557/PROC-0908-OO05-07

Molecular dynamics simulations of surface modification and damage formation by gas cluster ion impacts 査読有り

Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 242 巻 ( 1-2 ) 頁： 517 - 519 2006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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Damage formation process by gas cluster impact was studied using molecular dynamics simulations. Ar gas clusters with various sizes (several tens to several thousand) and energies (several to several tens keV, totally) were irradiated on Si substrates. The relationship between mean damage depth, incident energy and cluster size was examined and the model and conditions to cause damage by cluster impact were discussed.

DOI： 10.1016/j.nimb.2005.09.011

Molecular dynamics study of the angular dependence of reactive cluster impacts 査読有り

Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 241 巻 ( 1-4 ) 頁： 594 - 598 2005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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

The collisional processes of fluorine clusters impacting at various incident angles on bare silicon surfaces were studied, and the change of the surface profile, sticking probabilities of F atoms, sputtering yield and the distribution of the sputtered particles were examined. When a (F 2)3 0 0 cluster with 10 eV/atom impacts on a Si(1 0 0) surface at normal incident, the cluster penetrates the surface causing a spherical crater structure with the F atoms densely covered. As the incident angle increases, the penetration depth of cluster decreases and the simulation shows an asymmetric crater profile. Especially at an incident angle of 75°, the surface profile did not change but F atoms were deposited over a wide area. The distribution of sputtered particles also depends on incident angle. At normal incidence, the Si atoms are sputtered as well as silicon-fluoride molecules such as SiF and SiF2, while only SiFx molecules are sputtered at 75° of incident angle. From these results the surface etching process caused by reactive cluster impacts are discussed. © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2005.07.108

A Comparison of Ions with Neutrals Emitted from Semiconductors Bombarded by MeV Si Ions 査読有り国際誌

Yoshihiko Nakata, Satoshi Ninomiya, Takaaki Aoki, Hidetsugu Tsuchida, Jiro Matsuo, Akio Itoh

Transactions of the Materials Research Society of Japan 30 巻 ( 3 ) 頁： 797 - 800 2005年6月

Low Damage Smoothing of Magnetic Materials using Oblique Irradiation of Gas Cluster Ion Beam

Takaaki Aoki

MRS Proceedings 2005年2月

Molecular dynamics study of suface structure and sputtering process by sequencial fluorine cluster impacts 査読有り

T Aoki, J Matsuo

Surface Engineering 2004 - Fundamentals and Applications 843 巻頁： 189 - 194 2005年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：MATERIALS RESEARCH SOCIETY

In order to study the surface reaction process under cluster ion impact, molecular dynamics simulations of sequential cluster impacts of fluorine and neon clusters were performed. (F-2)(300) and Ne-600 clusters were accelerated with totally 6keV and irradiated on bare Si(100) target. By iterating impact simulation sequentially, change of surface morphology and composition of desorbed materials were studied. In the case of fluorine cluster impact, the rough surface structure was made compared with neon cluster impact because fluorine atoms adsorb on the target, which work to keep pillar structure on the surface, whereas Ne atoms evaporate immediately leaving spherical mound structure on the surface. From the study of desorption process, it was observed that large number of Si atoms are desorbed in the form of silicon fluorides. The major sputtered material was SiF2, but various types of silicon-fluorides, including the molecules consists of several tens to hundreds silicon and fluorine atoms, were observed. The distribution of clusters in desorbed materials obeyed the classical model of cluster emission from quasi-liquid phase excited with ion bombardment. From these results, the irradiation effects of reactive cluster ions were discussed.

DOI： 10.1557/proc-843-t5.7

A new secondary ion mass spectrometry (SIMS) system with high-intensity cluster ion source 査読有り国際誌

Matsuo, J; Okubo, C; Seki, T; Aoki, T; Toyoda, N; Yamada, I

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 219 巻 ( 1-4 ) 頁： 463 - 467 2004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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Secondary ion mass spectrometry (SIMS) with gas cluster ion beams (GCIB) was investigated with experiments and molecular dynamics (MD) simulations. A new cluster SIMS system with high-intensity cluster ion source has been developed. Ar cluster ion beam with the average size of 2000 was utilized as a primary ion beam. The beam diameter is less than 1 mm at the target position, and a current density of 10 μA/cm2 is obtained. The etch rate of Si with this current density is more than 20 nm/min, which is far beyond the etch rate in recent low energy SIMS system. The secondary ion intensity linearly increases with the acceleration voltage. A threshold voltage of a few keV for secondary ion emission was found. These results are consistent with previous sputtering experiments. © 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2004.01.103

Molecular effect on projected range in ultralow-energy ion implantation

Kimura, K; Oota, Y; Nakajima, K; Suzuki, M; Aoki, T; Matsuo, J; Agarwal, A; Freer, B; Stevenson, A; Ameen, M

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 211 巻 ( 2 ) 頁： 206 - 210 2003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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Silicon wafers of (100) orientation are implanted with 3 keV As + or 6 keV As2+ ions at room temperature with fluences 1 × 1014-4 × 1014 atoms cm -2. The depth profiles of implanted As are measured by high-resolution Rutherford backscattering spectroscopy. The observed projected range for As2+ implantation is larger than that for As+ by several percent, showing a molecular effect on the projected range. © 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0168-583X(03)01249-7

Atomistic study of cluster collision on solid surfaces 査読有り国際誌

Matsuo, J; Seki, T; Aoki, T; Yamada, I

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 206 巻頁： 838 - 841 2003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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

New surface modification processes have been demonstrated using gas cluster ion irradiations, because of the unique interaction between cluster ions and surface atoms, atomistic mechanisms of cluster ion bombardment must be understood for the further developments of this technology. Variable temperature scanning tunneling microscope in ultra high vacuum allows us to study ion bombardment effects on surfaces and nucleation growth at various temperatures. In the STM image of cluster-irradiated surface, large craters with diameter of about 10 nm were observed on Si(1 1 1)7 × 7 surfaces. The structure and size of the traces agree well with theoretical calculation. When the sample irradiated with Ar cluster was annealed at 600 °C, the hole remained, but the outer rim of the crater disappeared and the surface structure was reconstructed at the site of the rim. The depth of damage region in the target became shallower with decrease of the impact energy. These results indicate that low damage and useful surface modification can be realized using the cluster ion beam. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-583X(03)00874-7

Defect characteristics by boron cluster ion implantation 国際誌

Aoki, T; Matsuo, J; Takaoka, G; Toyoda, N; Yamada, I

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 206 巻頁： 855 - 860 2003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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Cluster ion implantation using decaborane (B10H14) has been proposed as a shallow implantation technique for LSI devices with gate lengths of several-tens nanometers. Experiments and computer simulations of low-energy boron monomers and decaborane clusters implantation were performed. Molecular dynamics simulations of B10 cluster implantation have shown similar implant depth but different damage density and damage structure compared to monomer (B1) ion implantation with the same energy-per-atom. For monomer implantation, point-defects such as vacancy-interstitial pairs are mainly formed. On the other hand, B10 generates large numbers of defects within a highly-amorphised region at the impact location. This difference in damage structure produced during implantation is expected to cause different annihilation processes. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-583X(03)00878-4

Cluster species and cluster size dependence of damage formation by cluster ion impact 査読有り国際誌

Aoki T., Matsuo J., Takaoka G., Yamada I.

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 206 巻頁： 861 - 865 2003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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Molecular dynamics simulations of Ne, Ar and Xe clusters with various sizes impacting on Si surfaces were performed in order to study damage formation processes. When cluster size ranged from several tens to several thousands and accelerated energy is 20 keV in total, each cluster impact caused surface damage in the shape of a crater. A larger number of displacements was found with the Xe cluster than Ne and Ar clusters of the same cluster size because the Xe cluster had a larger mass and momentum. However, when cluster size exceeded several thousands, different surface damage structures were formed depending on the cluster species. At a cluster size of 10,000, for example, a crater-like trace was still formed with a Ne cluster impact. However, both the depth of the crater and the number of displacements decreased as the atomic number of the cluster atom increased, which meant that the atomic and energy density irradiated on the surface is a dominant parameter in causing surface damage. These results indicate that the damage formation by cluster impact can be controlled by changing the cluster species as well as the incident energy and cluster size. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-583X(03)00879-6

Modeling of surface smoothing process by cluster ion beam irradiation 査読有り国際誌

Nakai, A; Aoki, T; Seki, T; Matsuo, J; Takaoka, GH; Yamada, I

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 206 巻頁： 842 - 845 2003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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Smoothing effect is one of the advantages of cluster ion beam. It is important to estimate an ion dose to achieve required surface smoothness. The smoothing rate with cluster ion beam depends on surface profiles. In this work, modeling of surface smoothing process with cluster ion beams was examined. Ar cluster ions with an energy of 20 keV was irradiated on rough Si Surface. Fast Fourier transform was applied to atomic force microscope data of 100 × 100 μm2, and power spectra were calculated. Smoothing rate depends on the wave number as well as the ion dose. Relationship between smoothing rate and wave number was derived. The surface smoothing process was modeled with the use of the wave number dependence of the smoothing rate. The calculated and the experimental surface profiles are in good agreements. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-583X(03)00875-9

Molecular dynamics study of damage formation characteristics by large cluster ion impacts 査読有り国際誌

Aoki, T; Matsuo, J; Takaoka, G

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 202 巻頁： 278 - 282 2003年4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：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Molecular dynamics simulations of various Ar clusters, with the size ranging 1-50,000 and the energy up to totally 50 keV, impacting on Si surfaces were performed. The cluster size and incident energy dependence on damage formation was examined. Two cluster-size depending parameters, the threshold energy to cause displacements and displacement yield, were proposed and modeled. These two parameters showed non-linearity depending on cluster size. The model function using above parameters reproduced the characteristics of damage formation by cluster ion impact. Two specific cluster sizes to cause maximum and no displacements on the surface were discussed, which is expected to provide useful information about optimized cluster ion beam conditions for various surface modification and thin-film formation processes. © 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-583X(02)01869-4

クラスターイオン衝突における非線形照射効果とそのプロセス応用査読有り

松尾二郎, 瀬木利夫, 青木学聡

高温学会誌 29 巻 ( 5 ) 2003年

　前のページ - 次のページ　

1
2
3
4
5
6
7
8
9