PRESSURE-DEPENDENCE OF THE NEGATIVE BIAS VOLTAGE FOR STABILIZATION OFCUBIC BORON-NITRIDE THIN-FILMS DEPOSITED BY SPUTTERING

Thin films of boron nitride were deposited by unbalanced magnetron spu ttering at pressures between 0.065 and 1.32 Pa in order to study the e ffects of pressure and negative substrate bias on the energy of the bo mbarding plasma ions and subsequent stabilization of the cubic phase. It was found that the threshold bias voltage for nucleation of films w ith a high percentage of the cubic phase increases with the product of the pressure and sheath thickness. This trend is explained in terms o f the changes in the average energy of the particles bombarding the gr owing film produced by pressure-dependent charge-exchange collisions i n the plasma/substrate sheath. This energy modification process has pr edictable consequences in complex deposition processes. (C) 1998 Ameri can Institute of Physics. [S0003-6951(98)02920-9].