Cubic Boron Nitride Formation by PECVD in the B-N-Cl-H System: Ionic and Chemical Aspects

Abstract BN thin films have been synthesized by r.f. Plasma Enhanced Chemical Vapor Deposition (PECVD) from BCl3 / N2 /H2 / Ar mixtures. c-BN formation has been studied through correlations between gas phase characterization (by Optical Emission Spectroscopy, Mass Spectrometry and electrical measurements) and thin film analysis (by Fourier Transformed Infra Red Spectrometry for structure determination). In particular, the occurrence of physical and possible chemical mechanisms is studied with the help of post-treatments of as-deposited BN coatings in pure Ar, Ar/H2 and Ar/Clb plasma mixtures. It is shown that, in addition to the well known ion-induced formation of the cubic phase, chemical etching also occurs, due to the presence of hydrogen and chlorine species, which leads to a relative increase in the cubic content of the thin film.