Multi-scale kinetic surface roughening of reactive-sputtered TaN thin films characterized by wavelet transform approach

Kinetic surface roughening of TaN thin films deposited by reactive sputtering was investigated by using atomic force microscopy. Wavelet transform method incorporating power spectrum density analysis was applied to extract the global and local surface morphologies of the films. Then the dynamical exponents of global and local surface roughening were calculated in terms of dynamic scaling theory. The results show that the kinetic surface roughening of TaN thin films exhibits multi-scale characteristics, where a set of local dynamical exponents (αl = 0.95, βl = 0.24) and global dynamical exponents (αg = 1.56, βg = 0.71) was obtained. The local surface roughening is dominated by the competition between linear surface diffusion and deposition flux noise, while the global surface roughening displays anomalous rapid-roughening behavior due to the preferred grain growth.