Optimization of Operating Parameters in a Planetary CVD Reactor Using Response Surface Methodology

Abstract

Film thickness uniformity is an important index to measure the quality of a deposited layer in selective epitaxial growth (SEG) of silicon using the chemical vapor deposition (CVD) process. The uniformity of a thin film is related to many parameters, such as rotation speed of a wafer, total flow rate, species concentration, susceptor temperature, and operating pressure. Therefore, it is very important to address the problem of coupling multiple parameters and solve the optimization in a computationally efficient manner. In this work, response surface methodology (RSM) is used to analyze the complex coupling effects of different operating parameters on silicon deposition uniformity. Based on the computational fluid dynamics (CFD) model, an accurate RSM model is obtained to predict non-uniformity with different parameters, including temperature, pressure, rotation speed of a wafer, and mole fraction of dichlorosilane (DCS). Analysis of variance (ANOVA) is conducted to determine the statistical significance of each factor in an empirical equation for the expected response. The results of ANOVA analysis indicate the goodness of fit of the regression model. The optimum combination of operating parameters of the problem considered in this study is a susceptor temperature of 1122.2 K, wafer rotation speed of 23.72 rpm, operating pressure of 112 Torr, and DCS mole fraction of 0.01186. The validation tests and optimum solution show that the results are in good agreement with those from the CFD model, and the maximum deviation between the computational solution and predicted values is 2.93%.