Process diagnostics during the deposition of cubic boron nitride

Using spatially resolved optical emission spectroscopy and Langmuir double probe technique, the magnetron deposition process of cubic boron nitride thin films has been investigated. The ion current to the r.f.-biased substrate electrode was estimated by means of Bohm's sheath criterion. In order to deposit the cubic boron nitride phase, a much higher ion energy is required in the d.c. magnetron in comparison to the r.f. sputtering magnetron mode at usually applied target power. Furthermore, there is a significant phase inhomogeneity across the substrate holder. Both facts have been explained in terms of the total momentum per deposited boron atom. The plasma excitation degree (vibrational and excitation temperatures) determined by emission spectroscopy was found to be higher in the r.f. sputtering mode. It has been shown that both in situ techniques applied can supply reliable information on the reactive magnetron deposition process. (C) 1997 Elsevier Science S.A.