Characteristics of Thermal Silicon Nitride Films Grown in Argon‐Diluted Ammonia

Abstract

Characteristics of silicon nitride films thermally grown in argon‐diluted ammonia have been studied. Typical film thicknesses were 30–45Å after nitridation for 10 min to 2h at 1150°C. The as‐grown films are oxynitrides with similar oxygen depth profiles irrespective of their different growth conditions. Origin of the observed high surface oxygen content in the films is suggested to be due to oxidation during wafer unloading. As the oxygen content of the film increases, the Si‐N infrared absorption band shifts toward higher wave numbers. Reduction of the interstitially dissolved oxygen in the silicon substrate was detected by infrared spectroscopy after the thermal nitridation cycle. This process is apparently accelerated by the injection of vacancies at the interface during direct nitridation of silicon. Steam oxidation resistance of thermal nitrides was found to be sensitive to the oxidation temperature and the thermal nitride growth conditions.