The present work focuses on the incorporation of -CH3 radicals in organic SiCO(H) films with low dielectric constant (k = 2.46). The SiCO(H) films were deposited by dielectric barrier discharge plasma method using a mixture of CH4 and Ar gases at different conditions (varying the frequency and pressure). The evolution of the film microstructure was investigated by means of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) absorption spectroscopy, and atomic force microscopy (AFM). Various bonds, C-C, C-O, Si-O, and Si-CH3, were observed in XPS. In XPS analysis, it is observed that at higher frequency range (from 1 to 5 kHz), -CH3 radicals (in the form of Si-CH3) increase significantly. FTIR absorption spectra consist of several vibrational bands: namely, Si-O-Si asymmetric stretching at 1034 cm(-1), symmetric deformation of the -CH3 group in Si -CH3 configuration at 1270 cm-1, C-H stretching of -CHx (x = 2 and 3) groups in the region between 3050 and 2750 cm(-1), and -OH related vibrational bands in the range between 3700 and 3150 cm(-1). The change in various deposition parameters causes the change in different Si-O-Si vibrational band ratio, and the intensity of C-H-x and Si-CHx. The film roughness was verified by AFM measurement. (c) 2007 The Electrochemical Society.