Phase Transformation in the Annealed Si-Rich SiNx Films Studied by Raman Scattering

Abstract

The Si-rich SiNx films were deposited on Si wafers by low pressure chemical vapor deposition (LPCVD) technique followed by annealing at (800 – 1200) °C. Excess (overstoichiometric) Si content in nitride films was calculated from Rutherford backscattering data (RBS). Existence and evolution of Si nanoclusters from amorphous to crystalline ones under high temperature treatment were confirmed by Raman scattering (RS) measurements. Amorphous Si clusters have already existed in as-deposited SiNx films. Thermal treatment results in the formation of additional amorphous nanoclusters and in their crystallization with anneal temperature increasing. Nitride films annealed at 1200 °C contain crystalline Si clusters only. It was revealed a dependence of Si wafer’s Raman scattering intensity on the temperature of SiNx/Si structures annealing. This information in combination with RBS data has allowed us to estimate and distinguish the excess silicon aggregated in clusters and the excess silicon distributed over the silicon nitride matrix.