Silicon oxide,silicon nitride,or silicon oxynitride thin films grown by plasma enhanced chemical vapor deposition (PECVD) have been widely used in the semiconductor devices or integrated circuits.In traditional PECVD,these thin films are often deposited in radio-frequency (RF) or microwave discharges sustained in mixtures of SiH4/N2O/NH3,SiH4/N2O/N2 and SiH4/O2/N2[1-5]with varying flow rates in which inert gases are often added in order to improve discharge characteristic In this work,a two-dimensional fluid model is established to investigate the characteristic of SiH4/O2/N2 discharge in a radio-frequency CCP reactor.