Structural and elastic properties of cubic boron nitride films

A thick, cubic phase, boron nitride film was deposited on a (100) Si wafer kept slightly above room temperature, by radio frequency (rf) magnetron sputtering. The rf target power was 150 W and the substrate bias voltage was −100 V. The film composition was checked by Auger electron spectroscopy (AES); the short-range order was investigated by Fourier transform infrared spectroscopy (FTIR) and micro-Raman spectroscopy. The film structure was assessed by glancing angle X-ray diffraction (GXRD). The elastic constants of the film were measured by surface Brillouin spectroscopy (SBS). To improve the visibility of Raman and Brillouin signals from cBN, the film was deposited onto a 600-nm thick titanium interlayer. The observed degradation of Raman features with respect to single crystal cBN is attributed to disorder and phonon confinement in our sample. Reliable values for the Youngʹs modulus E and the shear modulus G of cBN were obtained from SBS. Results from nanoindentation measurements on the same film are compared to SBS results.