Hydrogen Concentration and Bond Configurations in Silicon Nitride Films Prepared by ECR Plasma CVD Method

Abstract

The influence of deposition conditions on the hydrogen concentration and bond configurations in silicon nitride (SiN) films prepared by the electron cyclotron resonance plasma CVD(ECR P-CVD) method has been studied in comparison with those prepared by a conventional plasma CVD(P-CVD) method, by means of secondary ion mass spectrometry (SIMS), infrared absorption (IR) spectra and electron spin resonance (ESR). SiN films deposited at low microwave powers and a relatively high SiH4 flow rate had higher H concentrations than those deposited at high microwave powers. The hydrogen concentration was found to be in the range from 1.3×1022-5×1021/cm3 (13.8-4.7%) at microwave powers between 50 and 500 W. The bond configurations in the films are markedly dependent upon the deposition conditions. SiN films with only N-H bonds are thermally stable, even after annealing at 900°C in a dry N2 atmosphere, while almost all the H atoms are lost after annealing for films with both N-N and Si-H bonds. Annealing studies by ESR measurements revealed that the H concentration in the films has little influence on the spin density.