Radio frequency bias power effects on silicon nitride film deposited in SiH4-NH3 using a plasma-enhanced chemical vapor deposition

Silicon nitride films were deposited at room temperature in a plasma-enhanced chemical vapor deposition system. Ion energy and ion energy flux were measured with an ion energy analysis system. The effects of the radio frequency bias power on the ion energy distribution, deposition rate, refractive index, and surface roughness were examined along with the correlations between the ion energy diagnostics and film properties. The bias power varied from 30 W to 90 W. The surface roughness measured by atomic force microscopy was detailed in terms of the mean surface roughness and major pixel density. The deposition rate increased from 271 Å/min to 308 Å/min, increasing the bias power and correlation with the ion energy. Particularly, the refractive index increased with a decrease in the bias power. This is a unique feature resulting from the room-temperature deposition of silicon nitride film controlled in terms of the bias power. Moreover, the large variation from 1.94 to 2.49 facilitates the control of the refractive index as a function of the bias power. Strong dependency of the refractive index on the ion energy flux was also identified.