Thermal Stress in CVD PSG and SiO2 Films on Silicon Substrates

Abstract

Stress‐temperature relationships of APCVD and LPCVD and PSG films on silicon substrates were measured with the Newton ring method up to 1000°C. Compressive stress in PSG films at room temperature reduces and turns to tension above 100°C. Stress‐temperature curves of PSG have a maximum at about 500°C regardless of film compositions and deposition conditions. Heat‐treatment of APCVD PSG films at constant temperatures below or above the stress maximum temperature causes an increase or decrease of stress. Stress in APCVD on heating up to 1000°C is tensile while that in LPCVD film changes from compression to tension on heating though both films have the same stress maximum temperature. Stress of the films is attributed to swelling or shrinking caused by water adsorption or desorption up to the stress maximum temperature above which sintering and stress release take place. The stress maximum temperature corresponds to the solidus line in the binary system.