STUDY OF THE CHEMICAL-COMPOSITION OF SILICON-NITRIDE FILMS OBTAINED BY CHEMICAL VAPOR-DEPOSITION AND PLASMA-ENHANCED CHEMICAL VAPOR-DEPOSITION

Silicon nitride films were deposited by pyrolytic chemical vapour deposition (CVD) and plasma-enhanced CVD techniques. The effects on the stoichiometry of variations in the reactant gas flow were evaluated. Electron spectroscopy for chemical analysis, Fourier transform infrared (FTIR) and secondary ion mass spectrometry (SIMS) were used in order to clarify the differences in the composition of the films. The analytical information obtained with these techniques included the silicon-to-nitrogen ratio, N - H and Si - H group content, surface oxide and bulk contamination. It was found that the classic FTIR approach was unable to detect the low Si - H content in CVD films. This low Si - H level could, however, be detected by SIMS without interference at 31 a.m.u. as a 30SiH+ species.