Optical emission spectra of OMCTS/O2 fed plasmas used for thin film deposition

This paper is devoted to the optical emission studies of Octamethylcyclotetrasiloxane (OMCTS)/O2 derived, low pressure (0.1 Torr), 13.56 MHz RF plasmas. The emission is recorded with a resolution of 0.05 nm to two RF power densities of 0.25 and 0.50 W/cm2, at wavelengths of 180–1000 nm. Emitting atomic and molecular species in plasma are identified, and spatial variation in emission intensity is recorded through the space between electrodes. The hardness, elastic modulus, infrared absorbance, refractive index, and residual stress of the resulting plasma polymer films are presented. Most of the atomic and molecular emissions have been identified, and spectra can be used as a reference for OMCTS/O2 plasmas. Optical emission spectra are dominated by molecular CO, CO+, OH, and CO2+ bands, and atomic H and O lines. The absence of emissions from the Si, SiO, SiO2, CH, CH2, and CH3, together with the infrared absorbance of films, suggests that SiOxCy:H film formation occurs by way of the dissociation of C–H and Si–C bonds, as well as the polymerization of silica rings or long chains.