Characterization of Plasma Enhanced Chemical Vapor Deposition of Amorphous Silicon Films from 100°C to 400°C

Abstract

Amorphous silicon (a-Si:H) thin films with deposition temperatures ranging from 100°C to 400°C from two different deposition chambers have been analyzed and characterized using various techniques including the Atomic Force Microscope (AFM). These amorphous silicon films were deposited in two separate Plasma Enhanced Chemical Vapor Deposition (PECVD) chambers with different but similar hardware designs. Both chambers employed capacitively coupled plasma with RF power operating at 13.56MHz. During deposition the wafer sat on a resistively heated bottom electrode. The deposition temperature of the film was determined by the temperature of the heated bottom electrode or heater. One chamber had its heater fixed at 400°C while another had heater temperatures varied from 100°C to 300°C. SiH 4 gas and Ar were used for amorphous silicon deposition. The two chambers operating at different temperatures exhibited similar process trends. The deposition rates of amorphous silicon were found to be a strong function of the SiH 4 flow and RF power. The surface roughness and adhesion strength of the amorphous silicon films forming at different temperatures were compared. The quality of the amorphous silicon films was found to be related to the deposition heater temperature with a higher deposition temperature leading to a better quality amorphous silicon film.