Plasma Deposition and Characterization of Thin Silicon‐Rich Silicon Nitride Films

Abstract

Films of containing excess Si were prepared by plasma‐enhanced chemical vapor deposition at 350°C by the glow discharge reaction of gaseous (1.9% in helium) in in a tube‐type, hot wall reactor at 450 kHz RF frequency. The amount of silicon in the films was adjusted by varying the reactant gas‐phase ratio. The deposited films had a refractive index range of 1.90–2.70. Auger analysis (depth profiles) showed that the Si concentration in the films increased with refractive index. A small amount of oxygen contamination was observed on all film surfaces. X‐ray photoelectron spectroscopy measurements showed the presence of excess silicon, probably present as amorphous Si clusters in films with a high refractive index and oxygen contamination in all deposited film surfaces. Fourier transform infrared and nuclear reaction analysis for hydrogen showed that the hydrogen concentration ranged from 13 to 22 atomic percent and the hydrogen concentration decreased monotonically with increased refractive index. Etch rates of deposited films in glow discharge decrease monotonically with decreased hydrogen and increased silicon concentration in the films.