PREPARATION OF THIN HARD BORON-NITRIDE FILMS BY RF MAGNETRON SPUTTERING

Films (0.1-1 mu m) of boron nitride were grown on silicon (111), KCl and quartz by r.f. magnetron sputtering of a BN target in an Ar or Ar-N-2 atmosphere. The deposition was carried out at two pressures: 2 x 10(-3) and 2 x 10(-2) Torr. The compositions and structures of the BN films were determined by electron probe microanalysis, electron diffraction and IR analysis. Films obtained at an argon pressure of 2 x 10(-3) Torr had a stoichiometric composition. They were dense and hard and had low carbon and oxygen impurity levels. Films exhibited a high microhardness similar to that for films deposited by ion-assisted methods. Films obtained at an argon pressure of 2 x 10(-2) Torr had a small excess of boron and increased impurity levels. They were soft and porous. All films were either amorphous or microcrystalline with a hexagonal structure. Application of a negative bias voltage (60-100 V) to the substrate stabilized the cubic phase that was confirmed by three methods. The deposition conditions for obtaining stoichiometric hard BN films and the applicability of the above-mentioned analysis methods are discussed.