Surface morphology and growth mechanisms for sputtered amorphous silicon nitride thin films

Evolution of surface of sputter-deposited amorphous Si3N4 films growth on Si (100) substrates was investigated using atomic force microscopy (AFM). The scaling behaviors of the AFM topographical profiles were analyzed using the one-dimensional power spectral density. The results of root-mean-square surface height variation showed that there is a power law relationship between the surface roughness and deposition time. It is interesting to note that the growth exponent can be divided into one region and two regions, respectively, when Si3N4 films are deposited at different working pressures. A very low growth exponent of β = 0.07 ± 0.01 was found when Si3N4 films were deposited at a working pressure of 1.6 × 10− 1 Pa. However, the growth exponent β can be divided into two regions, which is β1 = 0.09 ± 0.01, β2 = 0.24 ± 0.03 and β1 = 0.09 ± 0.01, β2 = 0.33 ± 0.04, when the films were deposited at a working pressure of 2.1 × 10− 1 Pa and 2.7 × 10− 1 Pa, respectively. The mechanisms of anomalous dynamic scaling exponents of Si3N4 films deposited at different working pressures were discussed.