INFRARED ELLIPSOMETRIC CHARACTERIZATION OF MIXED-PHASE BN LAYERS DEPOSITED BY PLASMA-ENHANCED PHYSICAL VAPOR-DEPOSITION

The hollow cathode are (HCA) is characterized by a high electron densi ty and the existence of beam electrons, properties useful for plasma a ctivated deposition processes. Calculations of the power transferred t o boron show that solid boron can be heated up by the HCA plasma beam in a few minutes to a temperature where the electrical resistance beco mes very small. A HCA evaporation device is applied to form boron nitr ide layers on different substrate materials. The films were characteri zed by Fourier transform infrared spectroscopy as well as electron and X-ray diffraction. The boron evaporation rate was kept nearly constan t while the nitrogen pressure varied between 0.013 Pa and 0.27 Pa. At nitrogen pressures of p(N2)=0.08 Pa and p(N2)=0.13 Pa the layers were found to consist in part of the cubic phase. An infrared ellipsometer with a spectral range from 400 cm(-1) to 3500 cm(-1) was set up as an additional layer characterization method. As an example for nontranspa rent samples the infrared reflectance spectrum of a BN coated steel pl ate is shown.