Ion beam sputter deposition of AlN thin films to different time scales was carried out in reactive assistance of N+/N-2(+) ions. The incipient stages of the growth morphology were characterized using atomic force microscopy. Dynamic scaling theory was invoked to analyze the evolution of surface roughness and the growth mechanism therein. Two distinct exponents 'alpha' (static) and 'beta' (dynamic) were used to unravel the film growth characteristics. Our results show that as the deposition time (t) increases, 'alpha' decreases gradually and substrate surface coverage increases indicated by a decrease in critical length Lc. Dynamic scaling exponent 'beta' was estimated to be 0.36 for the deposition from isolated nuclei to full surface coverage of the substrate. During the growth, rms roughness of the film was increased from 1.99 to 3.42 nm as the deposition time was increased from 3 min to 15 min. Surface diffusion becomes the major roughening phenomenon while bulk diffusion subside it at each stage by smoothening to yield corresponding rms roughness. (C) 2015 Elsevier B.V. All rights reserved.