Numerical Simulation Of The Chemical Vapor Deposition Process Of Silicon Carbide

The wide band gap material, silicon carbide, is a very promising material for high power, high frequency, high temperature devices due to its unique properties. The main technology for high quality epitaxial growth of SiC is the chemical vapor deposition (CVD) technique. Many process parameters have important effects on the deposition rate, making the CVD process much more complex. Optimizing and improving the CVD process by the traditional method of trial and error are often expensive and time consuming. An important optimization step is modeling of the growth, where computer simulations can be used to achieve a deeper understanding of the deposition process, making development faster and less expensive and showing important guide significance to the experimental study.A complete3D model for the epitaxial growth of SiC in the horizontal hot-wall reactor is presented, incorporating flow, heat transfer, mass transfer, gas chemistry and surface chemistry. The commercially available CFD software Fluent is used in the simulation of SiC CVD with H2as the carrier gas and C3H8and SiH4as precursors. The rate-determining step is analysed. The influences of susceptor height, the C/Si ratio, the gas velocity and the inclined susceptor wall on the growth rate are discussed. The conclusions are educed as follows:(1) The etching effect of H2is significant at high temperatures. The higher the temperature is, the larger the etching rate is, and the etching rate of Si<s> is larger than the etching rate of C<s>(2) The major silicon containing species contributing to the deposition are SiH2and Si, and the major carbon containing species contributing to the deposition are C2H2and Si2C. The growth rate is controlled by the deposition process of carbon species.(3) The mass transfer resistance is larger than the reaction resistance, indicating that the rate-limiting process is the mass transport process.(4) Reducing the susceptor height contributes the deposition of gas species on the susceptor wall.(5) The gas How rate shows great impact on the uniformity of the deposition on the susceptor wall. And the smaller the susceptor height is, the higher the gas flow rate needed and the larger the growth rate.(6) When increases the C/Si ratio by increasing the flow rate of the C3H8at the inlet, the deposition rate on the fore end of the susceptor increases evidently. While on the tail end, the deposition rate arises slightly, sometimes even reduces as the C/Si ratio increases. This is due to the serious consumption of the deposition species on the fore end.(7) By changing the susceptor wall from horizontal wall to inclined wall, the deposition rate increases. This is due to not only the convection of the gas species contributes to the mass transport of deposited species, but also the inclined wall reduces the susceptor height.