Preparation of thin hard boron nitride films by r.f. magnetron sputtering

Abstract

Abstract Films (0.1–1 μm) 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-N2 atmosphere. The deposition was carried out at two pressures: 2 × 10−3 and 2 × 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 × 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 × 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.