Effect of substrate on surface morphology evolution of Cu thin films deposited by magnetron sputtering

Copper thin films were deposited onto rough Al2O3 and Si (100) substrates using R.F. magnetron sputtering technique at room temperature. Surface morphology of thin films was detected by atomic force microscopy (AFM) and was characterized by dynamic scaling theory. The effect of substrate on the surface evolution of thin films was investigated. Roughness exponent α and growth exponent β were obtained by height–height correlation function and root–mean–square (RMS) roughness measurement. The results show that surface roughness of Cu thin films on Al2O3 substrates first decrease and then increase with increasing thickness, which can be explained by the contribution of rough substrate surface profile. During the initial deposition, the rough substrate morphology leads to a decrease of the measured growth exponent value, while it has no effect on the measurement of roughness exponent. With regards to the effect of the rough substrate surface profile, α and β of thin films deposited on Al2O3 are 0.83 ± 0.05 and 0.32 ± 0.03, respectively, while those of thin films deposited on Si substrates are 0.78 ± 0.02 and 0.37 ± 0.04, which indicates that substrate type has an important influence on surface dynamic evolution.