Study of SiNx Thin Film Character with Gas Flow Rate in PECVD

摘要

Elements distribution, refractive index (RI) and stress of silicon nitride (SiNx) thin film under different gas flow rate conditions of plasma enhanced chemical vapor deposition (PECVD) was studied. Infrared spectrum, RI and stress of SiNx thin film were measured by infrared spectrometer, ellipsometer and stress instrument, respectively. Results showed that SiNx thin film had the lowest hydrogen Element when silane-ammonia flow rate was 1/4, and increase the flow rate of either gas would lead to more corresponding element (i.e. N in ammonia, Si in silane) and hydrogen bonds in deposited films. RI of thin film was decided by the content of nitrogen and silicon. Deposition mode was the most important factor in determining the stress of SiNx film, while in the gas-flow-rate-limited mode the stress was also lightly impacted by the content of hydrogen in the film.