The Composition and Physical Properties of LPCVD Silicon Nitride Deposited with Different  NH 3 / SiH2Cl2 Gas Ratios

Abstract

The composition and physical properties of low pressure chemical vapor deposition (LPCVD) silicon nitride films were studied. The samples were deposited at 770°C with different reactant gas ratios ranging from 2 to 20. Auger electron spectroscopy (AES) showed that the Si/N ratio was about 0.75, and the compositional uniformity as a function of depth was good for all samples. No excess Si clusters were detected by TEM for the samples annealed at 1000°C in for 5h. Only N‒H bonds were observed by infrared (IR) analysis. The amount of N‒H bonds in the asdeposited samples was estimated to be about . The normalized N‒H absorption peak area was found to increase by increasing values, while the amount of N‒H bonds was found to decrease after annealing at 1000°C in for 30 min. The plasma etch rates were found to increase by increasing values and showed a good correspondence to the trend of increasing the N‒H bonds. The film stress for all samples was tensile and had a level of . No difference was observed in the film's ability to act as an oxidation barrier for samples deposited with different values.