Structure analysis of cBN films prepared by DC jet plasma CVD from an Ar-N-2-BF3-H-2 gas system

The structure of the cBN films deposited by DC jet plasma CVD from an Ar-N- 2-BF3-H-2 gas system was investigated by transmission electron microscopy a nd electron-energy-loss spectroscopy. A sequent layered-structure of Si/amo rphous/hexagonal/cubic BN was revealed, which was also confirmed by the con focal Raman technique. For comparison, the phase composition, crystal size and crystallinity of cBN films deposited for different times at initial gro wth stage were studied by infrared spectroscopy, Raman spectroscopy and gla ncing-angle X-ray diffraction. A columnar growth of the cBN grains with the average column width of approximately 0.2 mum was observed. The columns we re proved to be cBN single crystals elongated from the nucleation sites on the hexagonal BN to the film surface. High-density twins and stacking fault s were observed on the {111} planes of the cBN crystals, which subdivided t he crystals into many lamellae of several to about 20 nm in thickness. (C) 2001 Elsevier Science B.V. All rights reserved.