Thermal Stability of Hydrogen in Silicon Nitride Films Prepared by ECR Plasma CVD method

Abstract

Infrared (IR) absorption measurements, hydrogen evolution experiments and ESR measurements have been carried out in order to study the thermal stability of hydrogen, bond configuration and defect structure in silicon nitride films (SiN) prepared by an ECR plasma CVD method and in part by a conventional plasma CVD method. It is shown that the SiN films deposited at high microwave powers in which the bond configuration of N-H is predominant are thermally very stable, even after annealing at 900 °C in a dry N2 atmosphere. The IR spectra scarcely vary before and after the annealing. The hydrogen evolution from SiN films was found to be highly dependent upon the deposition conditions and deposition methods. The amount of hydrogen evolved after experiments up to 900 °C becomes less as the microwave power increases. The temperature at which hydrogen evolution starts to take place for SiN films deposited by the ECR plasma CVD method is generally higher than that for the P-CVD method, except for ECR SiN films deposited at high gas pressure. ESR measurements revealed that the hydrogen concentration in SiN films has little influence on the spin density.