Duty Ratio-Controlled Surface Roughness of Silicon Nitride Film deposited using Room-Temperature SiH4-NH3-N2 Plasma

Silicon nitride films were deposited with mixed gasses of SiH4-NH3-N-2 using a pulsed, plasma-enhanced chemical vapor deposition system at room temperature. The surface morphology of the SiN films was investigated as a function of the bias power and duty ratio, which varied from 40 W to 100 W and 30% to 90%, respectively. The surface roughness is detailed in terms of the mean surface roughness, nonuniformity of the pixel height distribution, and minimum pixel range. Ion energy diagnostic data is correlated with the surface morphology. An empirical model constructed is used to examine the impact of the ion energy on the surface morphology. As the duty ratio varied under a fixed power level, the lowest degree of surface roughness was obtained at a relatively low duty ratio of 50% at all powers except100 W. It is not able that this is strongly correlated with the ion energy flux. Additionally, as the power varied at a fixed duty ratio, less surface roughness was noted at a relatively low power of 60 W. With variations in the power, the surface roughness strongly depended on the ion energy. For all variations in the process parameters, the surface roughness varied between 0.285 nm and 2.249 nm. The non-uniformity of the pixel height distribution was lowest at 50% at all powers except 60 W. A neural network model was utilized to explore the parameter effect.