Preparation of Titanium-Doped Diamond-Like Carbon Films With Electrical Conductivity Using High Power Pulsed Magnetron Sputtering System With Bipolar Pulse Voltage Source for Substrate

Titanium-doped diamond-like carbon (DLC) films with electrical conductivity are prepared by plasma-enhanced chemical vapor deposition using high-density pulsed Ar/C2H2 plasmas. Those plasmas are produced by high-power pulsed magnetron sputtering (HPPMS) system, whereas the titanium dope into the DLC films is carried out through titanium sputtering. A bipolar pulse voltage source is connected to the substrate and its holder. The HPPMS plasma temporally evolves during a pulse-on time of an HPPMS power source after the discharge is ignited. Then, the negative pulse voltage with a magnitude of 1.5 kV is applied for 10 mu s before the application of the positive pulse voltage with the magnitude lower than 1 kV and the pulsewidth of 10-15 mu s. The fraction of the intensity related to sp(2) carbon bond in X-ray photoelectron spectroscopy (XPS) C 1s spectrum is similar to 80% or more for any film. On the other hand, the fraction of the intensity related to sp(3) carbon bond is similar to 20%, resulting in the preparation of the films with moderate hardness. The fraction of the intensity related to the titanium component in the overall XPS spectrum is lower than 8%, whereas that of titanium-carbon bond component in the overall XPS spectrum is lower than 1.5%. The conductivity of the prepared films markedly increases to 609 S/cm and its value depends on the amount of titanium-carbon bond. On the other hand, the film hardness ranges between 10 and 15 GPa and it does not strongly depend on the content of titanium.