OXIDATION PROCESSES IN HYDROGENATED AMORPHOUS-SILICON NITRIDE FILMS DEPOSITED BY ARF LASER-INDUCED CVD AT LOW-TEMPERATURES

Hydrogenated amorphous silicon nitride films produced by ArF laser-ind uced CVD in parallel configuration using SiH4/NH3/Ar gas mixtures unde rgo post deposition chemical transformations when deposited at low tem peratures. These dielectric films are found to oxidise over time on ex posure to the ambient humid environment, when deposited at substrate t emperatures T-delta less than or equal to 250 degrees C. Time evolutio n of these oxidation processes have been monitored through FTIR spectr oscopy and ellipsometric analyses and substantiated with the deconvolu tion of the infrared spectra to track down intermediate oxidation spec ies. For T(delta)less than or equal to 200 degrees C, we observe a fas t oxidation process involving gradual elimination of the Si-N, N-H and Si-H peaks and simultaneous growth of Si-O and Si-OH peaks. Above thi s temperature, the oxidation process has been found to slow down consi derably and for T-delta greater than or equal to 300 degrees C stable films are obtained. Based on these data, we discuss the possible film composition dependent oxidation pathway that can lead to Si-N bond rup ture and creation of Si-O and Si-OH bonds. (C) 1998 Elsevier Science S .A.