| Project/Area Number |
12450127
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Osaka University |
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Principal Investigator |
KOBAYASHI Hikaru Osaka Univ. ISIR, Professor, 産業科学研究所, 教授 (90195800)
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| Co-Investigator(Kenkyū-buntansha) |
YONEDA Kenji Matsushita Electric Industrial Co., Ltd. Project Manager, プロセス開発センター, 主任研究員
TAKAHASHI Masao Osaka Univ. ISIR, Associate Professor, 産業科学研究所, 助教授 (00188054)
米田 健司 松下電器産業, プロセス開発センター, 主任研究員
毎田 修 大阪大学, 産業科学研究所, 助手
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥15,100,000 (Direct Cost: ¥15,100,000)
Fiscal Year 2002: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2001: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2000: ¥11,800,000 (Direct Cost: ¥11,800,000)
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| Keywords | platinum treatment / leakage current / silicon / silicon dioxide / MOS / chemical oxidation / O-ion / nitric acid oxidation / 極薄酸化膜 / PMA / POA / 界面準位 / SiO_2 / 低温プロセス / Si / SiO_2界面 / 白金触媒 / O-イオン / AFM |
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| Research Abstract |
We have developed a new method of decreasing a leakage current density flowing through silicon dioxide (SiO_2) layers. In this method, a platinum (Pt) layer of 〜 3 nm thickness is deposited on a SiO_2 layer, followed by heat treatment at 〜 300 ℃ in oxygen, and after the removal of the Pt layer, an alminum electrode is deposited, resulting in the <Al/SiO_2/Si(100)> MOS structure. Dissociated oxygen ions (O) are injected into the SiO_2 layer, and the ions react with defect states such as suboxide species in SiO_2 and Si dangling bond interface states at the Si/SiO_2 interface. The reaction results in the elimination of the defect states which work as a current path. Since the migration of O ions is enhanced in thin parts of the SiO_2 layer because of a high electrical field, oxidation selectively occurs in the thin part, leading to the improvement of the SiO_2 thickness uniformity and hence decreasing the leakage current density. When a positive bias voltage is applied to Si with respect to the Pt layer, the interface state density becomes lower.
We have found that SiO_2 layers of 〜 1.4 nm thickness formed by immersion of Si in an azeotropic solution of nitric acid possess a leakage current density as low as or slightly lower than those for thermal SiO_2 layers grown at high temperatures. Consequently, we have succeeded in the observation of a capacitance-voltage curve for ultrathin chemical SiO_2 layers for the first time. When an Al layers deposited and the specimen is heated at 200℃ in hydrogen, the leakage current density is greatly decreased to 1/20 〜 1/4 of those for thermal SiO_2 layers of the same thickness. It is concluded that the decrease in the leakage current density results from 1) elimination of interface states, 2) elimination of SiO_2 gap-states, and 3) widening of the band-gap energy of the SiO_2 layer.
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