Optical properties and microstructure of silicon nitride film synthesized by ion beam enhanced deposition

Abstract

Silicon nitride films with a stoichiometric ratio of Si 3N 4 have been synthesized by concurrent electron beam evaporation of silicon and bombardment with nitrogen ions. Infrared reflection spectra in the wavenumber range 1500–5000 cm −1 were measured for the silicon nitride films. Interference fringes were observed in the IR spectra. By detailed theoretical analysis and computer simulation of the IR reflection interference spectra, refractive index profiles of the films were obtained. The chemical composition and interface structure of the IBED Si 3N 4 films have been investigated using Auger electron spectroscopy (AES) in conjunction with in-situ sputtering. The characteristic Auger spectrum for Si 3N 4 was measured. In-depth composition profiles and refractive index profiles have been correlated using the Lorentz-Lorenz equation. The results show that the refractive index profile determined by the IR reflection is consistent with that obtained from AES.