Deposition of c-BN films in a hollow cathode arc evaporation device

Boron nitride layers were deposited as a function of substrate temperature, bias voltage and nitrogen partial pressure using a hollow cathode are as an evaporation source. The maximum substrate temperature was 1000 K where a maximum de bias voltage of -2000 V could be applied. The nitrogen flow rate varied from 5 to 50 seem. The boron flux rate to the substrate could be estimated by measuring the boron material loss in the crucible. The sticking coefficient and sputtering rate could be derived from the measured film thickness. The layers were characterized by FTIR spectroscopy and TEM. Plasma parameters were determined by Langmuir probe measurements. Parameter ranges could be identified where almost pure cubic boron nitride layers grew. The maximum content of the cubic phase (c-BN) is about 95%. A layer thickness of 580 nm was reached without the film peeling. An internal compressive stress of about LO GPa could be estimated. Parameter variations showed a strong dependence of the c-BN content on nitrogen partial pressure and bias voltage. The influence of the substrate temperature is less pronounced. The fluxes to the substrate are modelled by evaluating the measurement data of evaporation and deposition rates as well as that of the Langmuir probe and related to the c-BN content. Thus the results of this plasma-activated deposition method can be compared directly with data from ion beam assisted deposition experiments.