HARD BORON-OXIDE THIN-FILM DEPOSITION USING ELECTRON-CYCLOTRON-RESONANCE MICROWAVE PLASMAS

Hard boron suboxide thin films were deposited in an electron cyclotron resonance (ECR) microwave plasma system at substrate temperatures bel ow 300 degrees C. A high-temperature effusion cell, operated at 2200 d egrees-2250 degrees C, was used for injection of boron downstream of a n Ar/O-2 ECR plasma. B ion bombardment is estimated to have been up to 6% of the total boron flux, and Ar ion bombardment is estimated to ha ve contributed similar to 100 eV/deposited atom. Boron suboxide films with oxygen concentrations of 11% exhibited hardnesses up to 30 GPa, e qual to sapphire and near that of pure boron. The hardness/modulus rat io was 0.1, significantly better than that of sapphire (0.067) or soli d boron (0.074), indicating these films may be of interest for a varie ty of tribological applications. (C) 1994 American Institute of Physic s.