Bonding Structure of Silicon Oxynitride Grown by Plasma-Enhanced Chemical Vapor Deposition

Silicon oxynitride films were prepared by plasma enhanced chemical vapor deposition (PECVD) with N2O, NH3, and SiH4 precursors. X-ray photoelectron spectroscopy (XPS) and refractive index characterization showed that different film compositions, from silicon dioxide to stoichiometric silicon nitride, are achievable by tuning the flow rate of nitrous oxide in a mixture of precursor gases. The refractive index of silicon oxynitride (SiON) films is linearly proportional to the nitrogen content of these films, making these films a desirable candidate for optical waveguide applications. In addition, a detailed compositional analysis of the oxynitride films was conducted by XPS. By the Gaussian deconvolution of Si 2p XPS spectra, we confirmed that the structure of PECVD silicon oxynitride films should be in the form of the random bonding and the films should have homogenous optical and electrical characteristics.