Quantitative Detection of Oxygen in Silicon Nitride on Silicon

Abstract

The carbon, oxygen, and nitrogen levels in 500–2000Å films of CVD silicon nitride films have been measured using Auger electron spectroscopy in conjunction with inert gas ion sputtering. The quantitative depth distribution of oxygen throughout the film was determined and interfacial oxides 10Å thick were clearly resolved. Oxygen concentrations in various nitride films were observed to range from 0.4 to 7% (atomic), whereas carbon was below the detection limits. It was shown that bulk oxygen and carbon levels down to 0.05 and 0.2%, respectively, are detectable. The influence of oxygen on the silicon/nitrogen Auger peak height ratio was demonstrated and the presence of oxygen was correlated with changes in the optical index of refraction.