Spectroscopic Studies of a Magnetron Sputtering Discharge for Boron Nitride Deposition

R. Pintaske, Th. Welzel, M. Schaller, N. Kahl, J. Hahn, F. Richter
Technische Universität Chemnitz, Institut für Physik
Technische Physik / Physik fester Körper
D-09107 Chemnitz
Germany

Magnetron sputtering discharges for the deposition of cubic boron nitride have been investigated using optical emission spectroscopy and LANGMUIR double probes. Spatially resolved measurements revealed the inhomogeneous discharge structure with respect to the distribution of excited species, electron density, and electron temperature. The optical emission spectra were analysed by means of the LTE approach as well as the corona model. The vibrational excitation of the nitrogen molecule was examined. It was found that the excited levels of Ar and Ar⁺ were not occupied according to a BOLTZMANN distribution. The ratio of selected Ar and N₂ emission intensities provided a qualitative measure of the electron temperature which was determined by probe measurements. However, intensity ratios of Ar and Ar⁺ lines did not correspond to changes in electron temperature. Varying the electron density in a wide range it could be demonstrated that the excitation mechanisms do not remain constant. The vibrational temperature of the N₂(C³P_u) has been found to be much higher in the case of r.f. sputtering than in the d.c. mode.