Low-dielectric-constant SiOC(-H) thin films were deposited on p-type Si(100) substrates using plasma enhanced chemical vapor deposition (PECVD) from vinyltrimethylsilane (VTMS; CH(2) = CHSi(CH(3))(3)) and oxygen gas as precursors. To improve the structural, mechanical and electrical characteristics, SiOC(-H) films deposited using PECVD were post-treated by ultraviolet (UV) irradiation for various time intervals. Carbon content of the SiOC(-H) films increased before 240 s of UV irradiation time. But carbon-bonded functional groups of the SiOC(-H) film, in case of 480 s UV irradiation time, is replaced with Si-O bond. Because the Si-CH(n) bond groups are broken due to UV irradiation, Therefore, the films are formed with Si-O bond rich in the Si-O-C(-H) structure. The lowest relative dielectric constant, leakage current density, the elastic modulus and the hardness of SiOC(-H) with 240 s of UV irradiation time were about 2.07, 2.1 x 10(-7)A/cm(2), 43 GPa, and 3.68 GPa, respectively. The results indicate that the SiOC(-H) films exposed by UV irradiation improve the structural, mechanical, and electrical characteristics. (C) 2011 Elsevier B.V. All rights reserved.