IR-SPECTRA AND ETCH RATES OF PLASMA-ENHANCED CHEMICALLY VAPOR-DEPOSITED PHOSPHOSILICATE GLASS-FILMS

IR transmission spectra of phosphosilicate glass (PSG) films with 8 wt. % P prepared by plasma-enhanced chemical vapor deposition (PECVD) and CVD are compared. The differential IR spectra of PECVD and CVD PSG films become very similar after annealing for 4 h in water vapor at 850 degree C. The etch rate of a PECVD film in p-etchant, which is constant throughout the film thickness, is 400 A min** minus **1. However, the etch rate recorded after the film is subjected to annealing in water vapor at 850 degree C varies with the depth in the film, attaining values as high as 800 A min** minus **1 in the region near the outer surface of the film. The results are explained as due to the oxidation of P//2O//3 to P//2O//5.