Cubic boron nitride films by dc and rf magnetron sputtering: Layer characterization and process diagnostics

Cubic boron nitride films have been deposited by three different magnetron sputtering methods: r.f. sputtering of an h-BN target, r.f. sputtering as well as d.c. sputtering of a pure boron target. By heating the boron target up to 800 degrees C its intrinsic electrical conductivity becomes sufficiently high to sustain a stable d.c. magnetron sputter discharge. The process parameters required for maximum c-BN formation were different for the three methods investigated. This could be correlated to the process parameters measured by means of Langmuir probes and optical emission spectroscopy. The films were investigated utilizing Fourier-transformed infrared spectroscopy with respect to their phase composition and compressive stress. Investigating the delamination of c-BN films, humidity was found to play a crucial role.