Effects of target bias voltage on the electrical conductivity of DLC films deposited by PBII/D with a bipolar pulse

Energetic electrons and ions, which were induced by positive and negative pulses in C7H8 plasma, respectively, were bombarded alternately on a substrate in PBII/D process. The effects of pulsed negative bias voltage on the electrical conductivity of DLC films were studied. Conductivity and hardness of DLC films were measured by a four-point-probe method and microindentation method. Hydrogen concentration, sp2/sp3 ratio, Raman I(D)/I(G) ratio were also measured by ERD, XPS, Raman spectroscopy and the structure of the films was observed by HRTEM. As a result, the resistivity of the film decreased with negative pulse voltage and reached to 1mΩcm at −20kV, and the hardness was 5.4GPa. It has been shown that the electrically conductive DLC films are composed with cluster of graphite-like aggregate. The technique can be applied for conductive DLC coatings on three-dimensional substrate with high adhesion strength.