In this study, we evaluate the etch damage of silicon oxycarbide (SiOC) films in an inductively coupled plasma using a 2 MHz bias power frequency and compare it to the damage in a 13.56 MHz bias power system. For this study, CF₄/He/Ar or CF₄/C₄F₈/Ar mixed gas plasmas were used. To evaluate the plasma-exposed damage, ellipsometric spectroscopy (ellipsometry) and Fourier-transform infrared (FT-IR) spectroscopy were performed. The dielectric constant and Si-O/C-O area % ratios were extracted from ellipsometry and FT-IR results, respectively. We confirmed that ions among the plasma parameters, such as ions, ultraviolet, and radicals, have a significant impact on thin-film properties. Although the etching rate of the oxide film at 2 MHz was higher than that at a 13.56 MHz bias frequency, it was confirmed that the damage to the SiOC thin film at 2 MHz was lower than that at 13.56 MHz. In addition, FT-IR analysis proved to be a useful tool for evaluating the plasma damage in SiOC thin films. The polymer thickness was calculated through X-ray photoelectron spectroscopy. Based on these results, the effect of the polymer on the change in the Si-O/C-O ratio is discussed.

Keywords: Silicon oxycarbide, Dielectric constant, Fourier-transform infrared plasma etching damage, Surface characteristics