THE LOW-TEMPERATURE CATALYZED CHEMICAL VAPOR-DEPOSITION AND CHARACTERIZATION OF SILICON-NITRIDE THIN-FILMS

Silicon nitride thin films have been grown via low pressure chemical vapor deposition at substrate temperatures ranging from 662 to 904 K by the catalytic action of a heated tungsten filament. A tungsten filament heated to 2020 K was used to decompose ammonia, which reacted with silane introduced downstream of the filament to form silicon nitride films at deposition rates between 50 and 250 nm/min. The resultant films were characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and spectroscopic ellipsometry (SE). Infrared spectroscopy indicated that, under appropriate deposition conditions, the amount of bonded hydrogen in the films could be reduced to less than 3%. XPS sputter depth profiles showed that the level of oxygen in the films decreased as the silane flow rate was increased. Oxygen free silicon nitride films were obtained at high silane flow rates. XPS and SE were used to profile the films and to establish the thickness and composition of the bulk, surface, and interfacial layers. SEM confirmed the specular nature of the deposited silicon nitride films.