Role of H2 in the deposition of CNx layers by PE-HF-CVD

CNx films were deposited on various substrates using either dimethylamine (DA) precursor or the reaction between trichloroethylene (TCE) and ammonia with N2 or 92% N2+8% H2 mixtures as background gas. The nature of the chemical bonding in these films was characterized by FTIR spectroscopy, and the film composition was analyzed by RBS. The microstructure and morphology were observed by AFM, STM, TEM and SEM techniques. We found that introducing H2 into the background gas reduced film adhesion and allowed for lower deposition temperatures. Hydrogen etching causes removal of nitrogen, as well as of CH and NH bonds, from the films. Better CNx network connectivity and improved compactness were achieved in our experiment.