Fabrication of SiN thin films by RF biased microwave plasma CVD

The purpose of this study is to clarify the effect of ion bombardment during the deposition of silcon nitride film. Since silicon nitride is an insulator, ion bombardment was controlled by RF bias to the substrate. When the effective value of the RF voltage was increased from 0 to 120 V, the self-bias, which is an indicator of the acceleration voltage of ions is impinging on the film, monotonically changed from 0 to -75 V. Therefore, when RF voltage is increased, the ion bombardment increased, hydrogen content in the film decreased, the content of nitrogen and silicon in the film increased, and the film density increased. This phenomenon is caused by the acceleration of surface reaction due to the thermal effect on the film surface by the increase of ion bombardment. The Si/N ratio was constant regardless of the RF voltage.