Thermal stability of diamond-like carbon films deposited by plasma based ion implantation technique with bipolar pulses

Abstract

Silicon incorporated diamond-like carbon (DLC) films were deposited using a bipolar-type plasma based ion implantation technique, and the effect of the positive pulse voltage on the thermal stability of the DLC films was investigated. The positive pulse voltage was varied from 2.0 to 6.3 kV while the negative pulse voltage was maintained at − 5.0 kV. The deposited DLC films were annealed in air for 1 h at constant temperatures of 500 and 600 °C. As a result, an optimum positive pulse voltage exists for the high deposition rate and thermal stability of the DLC films, which correlates with the surface temperature during the film deposition. The DLC film deposited at a positive pulse of 4.0 kV, whose surface temperature during deposition was 300 °C, showed a typical DLC Raman spectrum even though the annealing temperature increased to 600 °C, and exhibited good friction properties. This high thermal stability is attributed to the effect of pre-annealing during the deposition and the formation of a stable and thick silicon oxide layer on the DLC surface when annealed in air. On the other hand, the thermal stability of the DLC film deposited at 2.0 kV, whose surface temperature during deposition was 150 °C, quickly deteriorated when the film was annealed at 600 °C.