Determination of radical densities by optical emission spectroscopy during the ECR plasma deposition of Si-C-N : H films using TMS as a precursor

Abstract

The ECR plasma enhanced chemical vapour deposition has been studied by optical emission spectroscopy in the substrate region. Tetramethylsilane (TMS) was used as precursor for the deposition of Si-C-N:H thin films in Ar-N2 and Ar-N2-H2 gas mixtures. Using absolute electron-impact cross sections available in the literature absolute densities of H, CH, and Si have been calculated from the emission intensities of these species according to the corona model with respect to electron temperatures obtained by Langmuir probes. The contribution of dissociative excitation out of H2 and TMS to the emission of the particles is accounted for. The investigations were carried out varying the precursor flow for different microwave powers, substrate potentials, and gas mixtures. By comparison of the radical number densities in the gas phase and the atomic deposition rate, conclusions are drawn concerning the deposition mechanisms of the Si-C-N:H films.