Fourier transform infrared study of rapid thermal annealing of a-Si:N:H(D) films prepared by remote plasma-enhanced chemical vapor deposition

Abstract

Fourier transform infrared spectroscopy has been used to study the behavior of bonded hydrogen and bonded deuterium in hydrogenated amorphous silicon nitride films [a‐Si:N:H(D)] that were deposited by remote plasma‐enhanced chemical vapor deposition (RPECVD) and had been subjected to rapid thermal annealing (RTA) from 400 to 1200 °C after film deposition. The amount of bonded hydrogen in the film and its distribution between Si–H and SiN–H bonding groups is correlated to the ratio (R) of the source gases: NH₃ to SiH₄. Chemical reaction pathways are proposed to account for bond dissociation and release of hydrogen from the films in the form of molecular H₂ and NH₃. As the bonded hydrogen population decreases with increasing RTA temperature, the Si–N bond population increases. This postdeposition bonding of nitrogen to silicon upon thermal release of hydrogen species is consistent with improvements in the electrical properties of RPECVD silicon nitride films after an RTA treatment at 900 °C.