Electron cyclotron wave resonance plasma assisted deposition of cubic boron nitride thin films

Cubic boron nitride (cBN) thin films have been deposited by sputtering the hexagonal boron nitride (hBN) target with nitrogen ions from a low-pressure plasma source. The electron-cyclotron-wave resonance (ECWR) plasma served both to sputter the hBN target and to simultaneously bombard the growing film. Deposits of over 90% cBN content were obtained with ion energies between 70 and 135 eV. The stoichiometry of the films was warranted by the extremely dense nitrogen ions arriving at the substrate. The frequency of the TO-mode for cBN on the Fourier-transform infrared (FTIR) spectra shifted up only slightly from the bulk value at 1065 cm(-1). A maximum thickness of 350 nm for the cBN layer was achieved. A cross-sectional transmission electron microscopy (TEM) image showed that the film grew in the turbostratic boron nitride (tBN), aligned hBN-arrays and cBN sequence. At the hBN-cBN interface, some nanoarches were identified. The corresponding interplanar distances for the hBN (0002) and the cBN (111) planes are 0.321 and 0.212 nm, approximately ideal for the 2:3 lattice matching. Both the high-resolution TEM image and the are pattern of the (111) reflection from selected-area electron diffraction revealed the textured structure of the cubic phase. (C) 2001 American Vacuum Society.