Synthesis and characterization of c-BN films prepared by ion beam assisted deposition and triode sputtering

Abstract

Boron nitride films deposited on unheated c-Si substrates by ion beam assisted deposition (IBAD) and triode sputtering (TS) techniques are studied. The composition, microstructure and crystallinity of the films obtained by the two techniques are compared The methods of characterization used in this study are: X-ray photo-electron, infrared, and Raman spectroscopies. High-resolution cross sectional TEM is used to confirm the optical results. In the case of films prepared by IBAD, the ion energy was 350–500 eV. The films were prepared from different gas mixtures of nitrogen and argon, boron was supplied by evaporation of elemental boron. TS films were prepared with 100% of nitrogen, the boron was supplied by sputtering a pure boron target. This study shows that, in comparison with TS samples, IBAD samples have higher chemical and physical stability. The particle-size dependence of frequencies and damping of optical phonons is studied for all samples from the analysis of Raman scattering and infrared spectra. A very important difference between the particle-sizes of IBAD and TS samples is observed. A progressive chemical etching by nitric acid at 80°C combined with infrared characterization was successfully performed on IBAD samples deposited at low ion flux and announces a mixture of sp2 and sp3 phases with high content of sp3 structure. All results are in full agreements with TEM results.