Modeling of microcrystalline silicon film deposition in a capacitively coupled radio-frequency plasma reactor

Abstract

We present a numerical model of plasma-enhanced chemical-vapor deposition of hydrogenated microcrystalline silicon (μc-Si:H) film from SiH4 and H2 gas mixtures in a capacitively coupled radio-frequency plasma reactor. The model takes into account electron-impact, gas-phase, and surface reactions within a well-mixed reactor model. Plasma parameters such as the electron density, the electron temperature, and the electron-impact reaction rates are determined through a discharge model and used as inputs for the reactor model. The gas-phase reactions include electron-impact and neutral–neutral reactions. Some of the surface reaction rates are determined using quantum chemical calculations and transition state theory. In the reactor model, concentrations of each chemical species are calculated at steady state using mass conservation equation uniformed throughout the reactor. Numerical results of the deposition rate as a function of the plasma reactor operating parameters show good agreement with experiments. Based on the model, the correlation between μc-Si:H properties, such as the crystal grain orientation and the hydrogen content, and deposition operating parameters has been studied using a design of experiment. Finally, optimal operating parameters are investigated using optimization techniques.