Dependence of hydrogen and oxygen incorporation on deposition parameters in photochemical vapor deposited mercury free silicon nitride films

摘要

Silicon nitride films have been deposited on p-type Si (100) by mercury-sensitized photo-chemical vapor deposition (photo-CVD) method varying deposition pressure and substrate temperature. Energy dispersive X-ray fluorescence spectra of the samples show that the incorporation of mercury in the films, if any, is below 20 ppm. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy studies show the incorporation of oxygen and hydrogen in all the films, which is a function of the deposition parameters. Higher substrate temperature favors the formation of Si-H bonds and reverse is the case for the formation of SiN-H bonds. The sample deposited at low temperature (170℃) shows the presence of less unreacted silicon (4%) in comparison to the sample (12.5% unreacted silicon) deposited at higher deposition temperature (250℃), but the variation of pressure shows no significant change in terms of the unreacted silicon. The incorporated hydrogen and oxygen passivate surface defects thereby influencing interface electronic state densities (D_(it)) and fixed insulating charges (Q_(ss)).