Effects of Ar ion beam bombardment on the formation of cubic BN in IBED

Abstract

Effects of argon ion beam bombardment on the formation of c-BN have been investigated. BN films were deposited by the ion beam enhanced deposition (IBED) method, in which boron was deposited on Si substrates by ion beam sputtering of a boron target at a deposition rate of 2000 Å/h and an ion beam of nitrogen and/or argon was bombarded concurrently onto the growing film at 500 eV and 100 μA/cm 2. The ratio of argon ions to nitrogen ions was varied by the flow rate ratio of Ar to N 2 gases fed into the bombarding ion source. The resulting films were characterized by FT-IR and XPS. The compressive stress in the films was estimated by the bending beam method. Formations of c-BN were observed when the Ar content in the feed gases ranged between 50 and 75 vol%. Relations among N/B content ratios, compressive stress and c-BN formation in the films show that both nitrogen and argon ion bombardments are necessary for the formation of c-Bn, but their roles are different. Nitrogen should be supplied as active ions to form chemical bonds of BN, while argon contributes for c-BN formation by making thermal spikes on the growing film. Ne, Kr or Xe ions were bombarded with nitrogen ions to compare the effect of argon ion bombardment. It was found that argon ion bombardment is most effective in inert gas ions for c-BN formation.