Growth of silicon nitride film by controlling plasma ion energy and duty ratio at room temperature

Abstract

Silicon nitride (SiN) films were deposited using a radio frequency (rf) pulsed-plasma deposition system in a SiH4-N2 plasma at room temperature. The effects of rf bias power and duty ratio on SiN deposition were investigated. The bias power and duty ratio were experimentally varied in ranges of 50 W to 90 W and 30 % to 90%, respectively. An ion energy analyzer was utilized to collect ion energy and ion energy flux. Little variations in low and high energies, respectively with the duty ratio was observed at a duty ratio of over 60 %. In contrast, ion energies sharply decreased with a decrease in the duty ratio to a range of 30 % to 60 % range. Modest variations in high and low energy fluxes were observed at duty ratio of over 40 % and 60%, respectively. Decreasing the bias power increased ion energy fluxes. In general, higher ion energy fluxes were observed at lower bias powers. The deposition rate strongly correlated with a low ion energy flux at 90 W. This was noted in a duty ratio range of 30 % to 50 % at 70 W. A high correlation with a high ion energy flux was also observed at 50 W. For all variations, the deposition rate ranged from158 A/min to 185 A/min.