HFCVD系统中衬底温度场及气相空间场的数值分析

Numerical Analysis of Substrate Temperature Field and Gas Spacial Field in Hot Filament CVD System

探讨了典型气氛中热丝辐射、气体热传导与对流、化学反应生热等因素对衬底温度的影响,建立了三维热丝辐射和二维热流耦合有限元模型,研究了各工艺参数对衬底温度场及气相空间场的影响。结果表明H2占主导地位的气氛中衬底表面的氢原子重组放热对衬底温度有较大影响,氩气气氛中原子重组放热对衬底温度影响很小;热丝温度对衬底温度的影响最大;进气口到衬底的距离及进气口气体流速对衬底附近的流场影响最大,适当提高进气口到衬底的距离有助于提高衬底附近流场均匀性,增大进气速度有助于突破热障提高衬底表面流速,但同时加剧了衬底附近流场的不均匀性。

Experiments were conducted in vacuum, argon and hydrogen environments to find out the effect of ＂chemical＂ heating on substrate temperature. Then, three-dimensional finite element model and two-dimensional coupling finite element model were built up. The effect of the hot filament temperature, the substrate-filament distance, the number of filaments, the inlet gas velocity and inlet-substrate distance is discussed. The results indicate that the reactions of atomic hydrogen have evident effect on the substrate temperature. Simulation results show that the filament temperature and the inlet gas velocity have remarkable influence on the substrate temperature filed and the gas spacial filed. Suitable inlet-substrate distance can improve the uniformity of gas velocity filed near substrate. Increase the inlet gas velocity can obtain higher gas velocity near substrate, but at the same time aggravate the inhomogeneity of velocity field. All the results provide the basis for high quality preparation of diamond film.