Low Temperature Deposition of SiNx Thin Films by the LPCVD Method

Abstract

Thin silicon rich nitride (SiNx) films were deposited using the LPCVD (Low Pressure Chemical Vapor Deposition) method. Silane diluted in argon and ammonia were used as the reactant gasses, and the low temperature deposition at 570 oC was used. The films were deposited on silicon (111) substrates. Films with the different values of the nitrogen content were deposited by varying the ratio of the flows of ammonia and silane in the horizontal tube reactor. The films were characterized in terms on the surface quality (by scanning electron microscopy), in terms of the nitrogen content x by time of flight elastic recoil detection analysis and by Raman and FTIR spectroscopy. The thickness and dielectric constant were measured by ellipsometry. The films were found to have a very smooth, homogeneous surface with nitrogen content that vary from x=0 to x=1 in dependence on the deposition parameters. The intensity of the Si-N stretching peak has shown strong correlation with the film thickness measured by ellipsometry. The films showed a smooth surface layer and the value of dielectric constant easily controllable by the ratio of the flow of the gases in the reactor.