The scaling behavior of surface roughness evolution of hydrogenated microcrystalline silicon (pc-Si:H) thin films prepared by hot-wire chemical vapor deposition (HWCVD) has been investigated using atomic force microscopy (AFM). The scaling exponents are compared for the films deposited under the different deposition pressures (P-g). The roughness exponent alpha, the growth exponent P and the dynamic exponent z are about 0.85, 0.44 and 3.45 (1/z = 0.29), respectively, for the films prepared at P-g = 5 Pa where gas phase reaction happened. At low deposition pressure of 0.3 Pa where no gag phase reaction occurred alpha and beta are reduced to 0.65 to 0.35, respectively. The effect of shadowing effect, sticking coefficient and surface diffusion of the main radicals on the variations of scaling exponents under different pressures has been discussed. (c) 2005 Elsevier B.V. All rights reserved.