Compositional and electrical properties of ECR-CVD silicon oxynitrides

Abstract

Silicon oxynitride layers were deposited by electron cyclotron resonance (ECR) plasma enhanced chemical vapour deposition (PECVD). Oxygen, nitrogen and 5% argon diluted silane were used as precursors. The gas composition in the plasma was varied over a wide range to get compositions from pure to layers with around 20% O content. Large flow ratios are required to get significant N concentrations in the deposited layers. Pure layers could only be obtained when flow was completely suppressed. The infrared spectra of ECR are very similar to those of thermally grown oxides, but significant differences were found between the ECR and the high-temperature CVD spectra. MOS devices fabricated with these layers show that the interface state density increases from about to when the layer composition changes from pure to pure .