Deposition of low stress polysilicon thin films using low-pressure chemical vapour deposition

Abstract

The deposition of polysilicon thin films on silicon wafers using low-pressure chemical vapour deposition (LPCVD) was carried out and the process parameters were optimized to obtain normal and low stress films. The films of thickness 150 nm to 2 microns were deposited on 4" and 6" silicon wafers and the thickness uniformity was measured using Dektak 6M surface profiler. The thickness variation across the wafer was found to be in 5-10% range. Stress measurements were carried out using X-ray diffraction method. We were able to deposit low stress films with stress ~14 MPa. The quality of the films was found to be good and they were used in fabrication of MEMS based silicon devices.