Structural, mechanical, and electrical properties of cubic boron nitride thin films deposited by magnetically enhanced plasma ion plating method

We proposed a novel process for improving cubic boron nitride (c-BN) film properties coated on Si substrates, using a magnetically enhanced plasma ion plating (MEP-IP) method. The method has two features: 1) To realize a stable anode current, the deposition of an insulating BN film on the anode electrode was controlled by adjusting the anode electrode temperature, and 2) a stable substrate current was generated by high-density Ar/N-2 plasma with a stable anodic current to promote the reaction between N radicals and B atoms evaporated onto the substrate. To prevent the delamination of the c-BN film from the substrate, a structure of the c-BN/t-BN/a-BN/B/Ti/TiN/Ti/substrate was designed. It was found that the hardness defined by the Knoop indenter increased with an increase in the substrate voltage, and simultaneously the friction coefficient decreases. The electrical capacitance measurement revealed superior interface property for the BN/TiN/Sistack structure after air exposure (the permittivity of the stack structure is similar to 13.8). We also confirmed the long-term stability of the c-BN film hardness to be 3000 to 4000HK after a five-year exposure. These results confirmed that no delamination occurred in the c-BN structure fabricated by the present MEP-IP method. (C) 2014 The Japan Society of Applied Physics