Direct Synthesis of TiN and BN Films from TiO₂ and B₂O₃ by Using Pulsed DC Plasma CVD Method

Abstract

  Boron nitride (BN) and titanium nitride (TiN) films which were made from stable oxide raw materials such as boric oxide and titania were synthesized on metallic substrates by using pulsed DC plasma chemical vapor deposition (PDCVD). Hydrogen gas was used as reducing gas for oxides in the process of CVD. Meantime, nitrogen gas nitrides the reduced materials on the surface of the substrate. In the plasma process when we used only nitrogen gas, both boric oxide and titania were not changed to nitride. However, when we used both nitrogen and hydrogen gases in the process, nitride films were synthesized on them. TiN grain size grew and degree of crystalline improved with increasing current density during the process. In case of BN, hexagonal h-BN was transformed into cubic c-BN under high current density. When the gas mixture ratio was H₂ / N₂ = 2.0, friction of BN films were improved, and the film was composed of 10μm diameter of island structure on the substrate.