Reduced bias synthesis of cubic boron nitride thin films by magnetically enhanced inductively coupled radio frequency plasma chemical vapor deposition

Thin films of cubic boron nitride (cBN) were deposited from a mixture of diborane (B2H6), nitrogen and argon gas by inductively coupled radio frequency (RF) plasma chemical vapor deposition. Ion bombardment is a necessary condition for the growth of cubic phase. A series of samples were gown by changing the substrate bias voltage and the input RF power. The films were characterized by studying Fourier transformed infrared spectroscopy (FTIR) and the glancing angle X-ray diffraction pattern. XRD spectra showed clear reflection from the cubic phase up to (311). Lattice distortion was observed due to the presence of compressive stress in the films. The threshold of the window of bias voltage for the synthesis of cubic phase was found to decrease when an axial magnetic field of 500 G was applied to the plasma. This red shift of the substrate bias, when the plasma was enhanced magnetically, supported the momentum transfer model for the growth of cubic phase. (C) 2002 Elsevier Science B.V. All rights reserved.