2000 Fiscal Year Final Research Report Summary
Oxidation mechanism of silicon and silicon-based ceramics in ozone-containing atmosphere.
| Project/Area Number |
11650730
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
NARUSHIMA Takayuki Tohoku Univ., Graduate School of Engineering, Asso.Professor, 大学院・工学研究科, 助教授 (20198394)
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| Co-Investigator(Kenkyū-buntansha) |
IGUCHI Yasutaka Tohoku Unvi., Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (90005413)
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| Project Period (FY) |
1999 – 2000
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| Keywords | ozone / oxidation / silicon / silicon carbide / silica / parabolic rate law / kinetics / rate-controlling step |
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| Research Abstract |
Introduction
The oxidation kinetics of silicon and silicon carbide were investigated in an oxygen-ozone atmosphere at 973 K, and the possible oxidation mechanism of silicon-based materials is discussed.
Experimental
The samples used for oxidation tests were single crystalline silicon, polycrystalline silicon carbide (CVD), and single crystalline α(6H)-silicon carbide. An oxygen-ozone mixture gas (ozone gas partial pressure : 2-7 kPa, total pressure : 0.1 MPa) was generated with a silent discharge ozonizer system using dry oxygen as a source gas. Oxidation temperature was 973 K.Thickness of the oxide film formed on a sample was measured by ellipsometry at a fixed refractive index (1.462). The oxide films were examined by secondary ion mass spectroscopy (SIMS).
Results and discussion
(1) Oxidation kinetics
Parabolic behavior was observed at 973 K in oxygen-ozone mixture gas for the oxidation of silicon carbide C-face, Si-face and silicon. The oxidation rates of silicon and silicon carbide were much higher than those in pure oxygen. Atomic oxygen supplied by the dissociation of ozone gas seems to cause the increasing of oxidation rates, and the atomic oxygen diffusion through silica film is a rate-controlling process for oxidation because parabolic rate constant increased linearly with ozone gas partial pressure.
(2) High oxidation rate of SiC C-face
The oxidation rates of silicon carbide C-face in ozone-containing atmospheres are higher than those of Si-face and silicon. The higher oxidation rates of C-face than those of silicon may be caused by carbon in silica film formed on C-face detected with SIMS.
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