Thermal effects on LPCVD amorphous silicon

Abstract

The effects of thermal annealing on amorphous silicon deposited using low-pressure chemical vapour deposition (LPCVD) are presented in this paper. The amorphous silicon film is being subjected to different annealing conditions ranging from 600 to 900 °C for a varying period of 30 to 90 min holding time in nitrogen ambient. X-Ray diffraction (XRD) shows that crystallization of amorphous silicon to poly-silicon starts to occur after 30 min of thermal cycle at 600 °C. Atomic force microscope (AFM) has been used to study the surface roughness and grain size of the films after different annealing times and temperatures. The nanocrystalline grains result in photoluminescence behavior. Stress measurement, using curvature analysis, shows that the stress magnitude reduces with decreasing annealing temperature and time. This is likely due to stress relief during grain growth and crystallization at higher temperatures. The detailed study of the structural, morphology and property changes in amorphous silicon upon annealing will be presented.