INFRARED-SPECTROSCOPY INVESTIGATION OF CUBIC BORON-NITRIDE FILMS

FT-IR spectroscopy have been used for identifying both the structure o f BN and the intensity of the compressive stress in cubic boron nitrid e (c-BN) film prepared by a unbalanced rf (13.56 MHz) magnetron sputte ring of a hexagonal boron nitride target in a mixture argon and nitrid e discharge. A T(temperature)- V(negative bias) phase diagram was obta ined using the phase structure identify by IR spectra. Comparing the r eflection infrared spectra (RIR) with the transmission infrared spectr a (TIR) measured from same c-BN film, it is firstly found that RIR pea k position of c-BN is lower than TIR peak position of c-BN, this means that the compressive stress on the surface layer of c-BN film is smal ler than that inside c-BN film, may be this is the reason why thicker c-BN film can not be synthesized. A higher IR peak position of 1064 cm (-1) and a lower peak position 1004.7 cm(-1) were detected from a brok en and partly peeled off cBN film. The peak position of 1064 cm(-1) ag rees with that of bulk c-BN at 1065 cm(-1) which was synthesized at hi gh temperature and high pressure, while the peak position of 1004.7 cm (-1) accords well with the result calculated(1004 cm(-1)) by Wentzcovi th and it may be closes to that of the stress free value of c-BN. Usin g the result measured by Ulrich, the shift rate of IR peak position of c-BN in the films is about 3.8 cm(-1)/Gpa to be obtained.