The low dielectric SiOC(-H) films can be damaged by oxygen plasma during photoresist stripping. In this work, we have studied the CH4 plasma treatment to improve the characteristics of the SiOC(-H) film. Posttreated SiOC(-H) film in CH4 plasma showed the decreased leakage current density of 1 A/cm(2), which was lower two to three orders of magnitude than that of nontreated SiOC(-H) films. Unlike the nontreated SiOC(-H) films, Fourier transform infrared (FT-IR) absorbance spectrum of posttreated SiOC(-H) film remained almost unchanged after O-2 ashing. The dielectric constant of the treated SiOC(-H) film also did not change much. The CH4 plasma treatment can provide additional hydrogen and carbon to passivate the inner structure of SiOC(-H) films. Therefore, the properties of SiOC(-H) films are significantly enhanced by CH4 plasma treatment. (C) 2004 Elsevier B.V. All rights reserved.