Papers by Author: Hideki Ito

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Authors: Hidekazu Tsuchida, Isaho Kamata, Masahiko Ito, Tetsuya Miyazawa, Norihiro Hoshino, Hiroaki Fujibayashi, Hideki Ito, Masami Naitou, Hirofumi Aoki, Koichi Nishikawa, Emi Makino, Yuichiro Tokuda, Jun Kojima
Abstract: This paper introduces our recent challenges in fast 4H-SiC CVD growth and defect reduction. Enhanced growth rates in 4H-SiC epitaxial growth by high-speed wafer rotation and in a high-temperature gas source method promoting SiC bulk growth by increasing the gas flow velocity are demonstrated. Trials and results of deflecting threading dislocations by patterned C-face 4H-SiC epitaxial growth are also shown.
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Authors: Hiroaki Fujibayashi, Masahiko Ito, Hideki Ito, Isaho Kamata, Masami Naitou, Kazukuni Hara, Shoichi Yamauchi, Kunihiko Suzuki, Masayoshi Yajima, Shinichi Mitani, Katsumi Suzuki, Hirofumi Aoki, Koichi Nishikawa, Takahiro Kozawa, Hidekazu Tsuchida
Abstract: A single wafer type 150 mm vertical 4H-SiC epitaxial reactor with high-speed wafer rotation was developed. The rotation of the wafer at high speed significantly enhances the growth rate, and high growth rates of 40–50 μm/h are possible on 4°off-cut 4H-SiC substrates. In addition, a low defect density and smooth surface without macro step bunching can be achieved. Excellent uniformity of thickness and doping concentration was obtained for a 150 mm wafer at a high growth rate of 50 μm/h.
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Authors: Yoshiaki Daigo, Akio Ishiguro, Shigeaki Ishii, Hideki Ito
Abstract: In this study, influence of both Si/H2 ratio and C/Si ratio on growth rate uniformity and carrier concentration uniformity of n-type 4H-SiC epitaxial films grown by high speed wafer rotation vertical CVD tool was investigated. It was found that changes in radial profile of the growth rate and the carrier concentration obtained by varying Si/H2 ratio showed quite similar behavior to those obtained by varying C/Si ratio. Such a similar trend would suggest that the distribution of local C/Si ratio near the wafer surface changes depending on total Si/H2 ratio similarly to total C/Si ratio. Additionally, by using this relationship, both the growth rate uniformity of 49.2 μm/h ±1.78% (1.15% σ/mean) and carrier concentration uniformity of 1.08 ×1016cm-3 ±6.15% (3.40% σ/mean) was achieved.
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Authors: Kohei Shioda, Keisuke Kurashima, Hitoshi Habuka, Hideki Ito, Shinichi Mitani, Yoshinao Takahashi
Abstract: In order to develop a quick and practical cleaning process for the silicon carbide chemical vapor deposition reactor, the pyrolytic carbon-coated susceptor was used. The 30-μm-thick silicon carbide film was formed on the susceptor; the film was cleaning by chlorine trifluoride gas at 460 °C for 15 min. The remained fluorine was removed by the annealing at 900 °C in ambient hydrogen. The pyrolytic carbon surface did not suffer from any damage, because the pyrolytic carbon film surface morphology after the cleaning process was the same as that before the silicon carbide film deposition.
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Authors: Yoshiaki Daigo, Akio Ishiguro, Shigeaki Ishii, Hideki Ito
Abstract: 4H-SiC homo-epitaxial films were grown using a high speed wafer rotation vertical CVD tool, and effects of wafer rotation speed during initial temperature ramping before epitaxial growth were investigated. Also, the effects of conditions during growth of the highly doped buffer layer on both surface and PL defect densities were investigated. It was found that the wafer rotation speed during the temperature ramping has a large influence on the surface defect density of the films. Especially, triangles generated from small pits were considerably reduced in the samples grown at a higher wafer rotation speed during the temperature ramping. The phenomena could be explained as a result of suppressed interfacial reaction between down-falls (DFs) and the wafer surface. Additionally, it was found that the density of basal plane dislocations (BPDs) on a drift layer is remarkably reduced by adjusting the C/Si ratio during growth of the buffer layer grown prior to the drift layer. By applying higher wafer rotation speed during the temperature ramping and optimizing the C/Si ratio for the growth of the buffer layer, a total defect density of 0.75 cm-2 on the film, which includes DFs, triangles, DF-triangles, stacking faults (SFs) and BPDs, was achieved.
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Authors: Masahiko Ito, Hiroaki Fujibayashi, Hideki Ito, Isaho Kamata, Masami Naito, Kazukuni Hara, Shoichi Yamauchi, Kunihiko Suzuki, Masayoshi Yajima, Shinichi Mitani, Katsumi Suzuki, Hirofumi Aoki, Koichi Nishikawa, Takahiro Kozawa, Hidekazu Tsuchida
Abstract: The effects of high-speed wafer rotation for 4H-SiC epitaxy in newly developed 150 mm vertical reactor is investigated by simulation analysis. The simulation model shows a good agreement with experimental results. It is revealed that a combination of high-speed wafer rotation as high as 1000 rpm and relatively high system pressure of 267 mbar is effective to reducing boundary layer thickness above the 4H-SiC wafer, and greatly enhances the epitaxial growth rates. The growth rate increase ~2 times using the combination of high-speed wafer rotation and relatively high system pressure.
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Authors: Kohei Shioda, Hitoshi Habuka, Hideki Ito, Shinichi Mitani, Yoshinao Takahashi
Abstract: In order to develop a cleaning process for the silicon carbide chemical vapor deposition reactor, the susceptor coating materials are developed for protecting the susceptor from the etching by chlorine trifluoride gas. The chlorine trifluoride gas does not give a serious damage to the pyrolitic carbon film at the temperatures lower than 480 °C, at which temperature the quick and practical reactor cleaning process is expected to be possible
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