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摘要
The chemical kinetics active during the epitaxial chemical vapor deposition (CVD) of SiC thin solid films performed in presence of chlorine has been investigated using gas-phase and surface kinetic models that incorporate p- and n-doping mechanisms, and the predictions of the model have been compared with experimental data collected in an industrial reactor. It was found that the inclusion of some reaction pathways recently developed to describe the CVD of Si from SiHCl3 leads to a considerable increase in the gas-phase reactivity, which shows that the SiHxCl4-x chlorosilanes are at chemical equilibrium in the temperature ranges at which SiC is usually deposited. The predicted growth rate profile is in good agreement with the experimental data, suggesting that the mechanism proposed here may be used to optimize deposition profiles in existing or newly developed SiC growth reactors. Two mechanisms are also proposed to describe the n and p doping of SiC films when N-2 and Al(CH3)(3) are used as dopant precursors. It was found that good agreement with the experimental data is obtained when it is assumed that the SiN radical is the N-dopant precursor, thus suggesting that the gas-phase chemistry involving Si and N-2 may be more active than previously thought. In regard to the p-doping mechanism, it was found that atomic Al is formed in the gas phase in a concentration sufficient to justify the observed doping levels, while AlCl is the most stable gas-phase species. The quantitative simulation of experimental trends was possible assuming that the SiC film reaches saturation in Al and that this alters the surface chemistry, favoring the conversion of surface Al to the unreactive AlCl species.
- 出版日期2014-6-4
