Plasma enhanced chemical vapor deposition of nitrogen-incorporated silicon oxide films using TMOS/N 2O gas

Abstract

Plasma enhanced chemical vapor deposition (PECVD) of nitrogen-incorporated silicon oxide thin films using TMOS (tetramethoxysilane) and N 2O plasma is studied. The effects of the TMOS and N 2O pressure ratio on the properties of the film and the plasma are investigated. The intensities of light emission from molecules and radicals in the plasma are measured by optical emission spectroscopy (OES). The deposited films are analyzed by in-situ ellipsometry, and Fourier transform infrared spectroscopy (FTIR). The optical properties are measured by photoluminescence (PL). As the partial pressure of N 2O decreases, the refractive index begins to decrease, reaches a minimum, and then increases again. When the oxygen content in the plasma phase reaches a maximum, the refractive index reaches a minimum. We attribute the decrease of the refractive index to the incorporation of more oxygen. The FTIR absorption band from about 850 to 1000 cm − 1, which can be attributed to the formation of SiON is observed. A broad PL appears around 1.9–2.4 eV. As the oxygen content increases, the PL spectrum shifts toward a higher energy.