Stability and process parameter optimization for a vertical rotating ZnO-MOCVD reaction chamber

Abstract

Developing an understanding of the cavity stability underlying the metalorganic chemical vapor deposition (MOCVD) of ZnO is critical to the fabrication of oxide-based devices. Therefore, computational fluid dynamics (CFD) was used to study the process parameters (e.g., the growth temperature, total gas flow, chamber pressure, and substrate speed) of the MOCVD H-type reaction chamber for four states in the cavity: buoyancy-induced flow, plug flow, rotating-plug flow, and rotating flow. Based on these states, criteria for determining stable and unstable flows were determined. These can be presented on the pressure–rotation rate spectrum, which can be used to visualize the effects of specific process parameters on the flow stability. In order to obtain a good film deposition rate in the stable flow state of the cavity, a response surface model and genetic algorithm were also used to optimize the process parameters. The coefficient of variation of the optimized ZnO film was reduced to 2%, which greatly improved the film quality. This study provides a comprehensive insight into the transport phenomena of the MOCVD H-type reaction chamber, including coupled heat and mass transfer and chemical reactions, and presents the optimal combination of parameters to provide a useful reference for obtaining high-quality thin films.