Simulation and optimization of polysilicon thin film deposition in a 3000 mm tubular LPCVD reactor

Abstract

The high photoelectric conversion efficiency of tunnel oxide passivating contacts (TOPCon) photovoltaic (PV) cells and their process compatibility are increasingly recognized by the industry, making it of growing importance to develop deposition process technologies for high-capacity polysilicon thin films. Currently, the size of LPCVD reactors for preparing polysilicon thin films in the industry is getting enlarged, which directly leads to the degradation of axial uniformity of polysilicon thin films. In this paper, a coupled multi-physics field model is established to simulate the polysilicon thin-film Low Pressure Chemical Vapor Deposition (LPCVD) process based on COMSOL Multiphysics platform, and the validity of the model is verified by comparing experimental data with simulation results. By investigating the flow field, thermal field, chemical reaction field and surface reaction field, the effects of the process parameters such as chamber temperature and pressure are investigated, as well as characteristics of the polysilicon thin films deposition. The results show that the uniformity of thin films decreases with increasing temperature and pressure, and the deposition rate of thin films increases as temperature and pressure increase. With the help of optimized the process parameters, the deposition rate of polysilicon thin films was increased by 13.0% and the uniformity of thin films was controlled above 96%. The uniformity of the films can be further improved to 96.7% by optimizing the temperature zone parameters and adopting the wafers placement strategy.