Synthesis of 3C-SiC Films on Si(111) by SiH4/C2H2/H2 - CVD Reactiln System
| Autor: | Hu, Ming-Shien, 胡銘顯 |
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| Rok vydání: | 2001 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 Stoichiometric SiC films on Si(111) have been synthesized using the SiH4/C2H2/H2-CVD reaction system. The successive two step CVD, carbonization of Si substrate followed by SiC film growth, is utilized for synthesizing 3C-SiC films. For carbonization process, the effect of carbonization time and temperature to the SiC film growth has been investigated. It is found that carbonization time plays a key role in determining the surface roughness of Si substrate. Insufficient or over carbonization resulted in a rough surface, which deteriorates the crystalline property of SiC films. An optimum carbonization conditions of C2H2 flow rate = 3.2 sccm, H2 flow rate = 352 sccm, carbonization time = 8 minutes, carbonization temperature = 1170℃, and total pressure = 5 Torr has been conducted. For film deposition, the effects of [SiH4]/[C2H2] flow ratio, growth temperature, H2 addition, and temperature program to the growth were investigated. We found that the film growth rate is as a function of SiH4 partial pressure with an exponent of about 0.67 and independent of C2H2 partial pressure. The activation energy of the surface reaction is found to be 54.8 kcal/mol, quite close to the energy barrier of SiH4 gas-phase decomposition indicating that the surface reaction rate is dominated by SiH4 gas phase decomposition within the thermal boundary layer above the Si substrate. In addition, it is found that the [Si]/[C] composition decreases with H2 flow rate, indicating that H2 plays a crucial role on depressing the extent of SiH4 decomposition. Furthermore, the effect of various temperature programs on the crystalline property shows that the crystalline property and surface morphology of the SiC films become deteriorated when sudden introduction of SiH4 and C2H2 at a ramp up of growth temperature. One possibility is that sudden delivery of SiH4 may cause much Si nucleation at high temperature, which may be responsible for the rough surface of the SiC films. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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