Analysis of the transition layer in silicon nitride films deposited by a low‐pressure chemical vapour deposition

Abstract

A silicon nitride film was deposited on an Si(100) substrate with a silicon dioxide surface layer from NH 3 and SiH 2 Cl 2 by low-pressure chemical vapour deposition under various conditions. The etching rates of the silicon nitride films by buffered hydrofluoric acid (BHF) were investigated using Rutherford backscattering spectroscopy. The change of the etching rate at the interface region suggested the existence of a transition layer on the interface between the silicon nitride film and the silicon dioxide layer on the substrate. The silicon concentration of the transition layer is higher than that of the silicon nitride. The existence of a transition layer was also confirmed by angular-resolved XPS. Measurement of the etching rate of the silicon nitride films by BHF was applied to clarify the relation between the deposition conditions of the silicon nitride films and the thickness of the transition layer. The growth of the transition layer was controlled by nitridation of the substrate in ammonia ambient before deposition of the silicon nitride film.