Deposition of TiB₂ films by a co-sputtering method

We deposited Ti_1-xB_x films onto molybdenum by the co-sputtering deposition method. The sputter target is composed of a titanium disk 150 mm in diameter on which a suitable amount of boron particles are placed. The coating temperature is 870 K. The deposited Ti_1-xB_x films are then characterized by conventional metallurgical techniques. It is recognized that the present coating method can produce stoichiometric TiB₂ (titanium diboride) films having the same chemical bonding state as sintered TiB₂ which is formed under thermal equilibrium conditions. The deposited stoichiometric TiB₂ films, however, do not crystallize well when they are deposited without a negative bias voltage applied to the substrates. The application of a small negative bias voltage to the substrate is found to enhance crystallization of the deposited TiB₂ films. The crystallized TiB₂ films have a preferred (001) orientation.