The optical properties of sputtered amorphous silicon nitride films: Effect of RF power

Recently great interest has been paid to amorphous silicon nitride thin films which have found a large range of applications. Certain device processing requires a low temperature of film deposition, thus making sputtering a potentially useful fabrication technique. In order to investigate the influence of the radio frequency (RF) power on the optical properties of amorphous silicon nitride, films were deposited using powers between 100 and 400 W. Infrared spectroscopic analysis indicates that the concentration of Si-N bonds is reduced with increase in the RF power. However, the concentrations of Si-Si bonds and = N-0 and = Si-0 dangling bonds are enhanced. A decrease in the optical gap and an increase in the gap state density, refractive index and valence band tail width are observed in films deposited at high RF power.