Thermal stability of metal containing diamond-like carbon thin film fabricated by dual plasma deposition

Diamond-like-carbon (DLC) films have an amorphous structure comprising a sophistical carbon matrix and have attracted a great deal of scientific interest. Metal-doped DLC (Me-DLC) can possess superior properties as metal nano-clusters or nanocrystalline metallic carbides can be embedded in the carbon network. Therefore, Me-DLC exhibits good adhesion to the substrate, high hardness, low friction coefficient and high magnitude of conductivity. In this work, a metal cathodic vacuum arc and acetylene dual plasma are synchronized to produce Me-DLC. We systematically fabricate the Me-DLC films by varying the acetylene flow rate and substrate bias voltage. Our results acquired by Rutherford backscattering spectrometry (RBS) show that the film thickness and metal content can be controlled by the process windows. Four point probe measurements illustrate a decrease in the resistivity with increasing metal content whereas x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) results show the formation of carbide phases in the carbon matrix. To evaluate the thermal stability of the thin film, both undoped DLC and Me-DLC films are annealed at a series of temperature in argon ambient. Raman scattering results reveal that the Me-DLC films can tolerate a high annealing temperature without serious graphitization. It is believed that metals incorporation retards the restructuring of the carbon matrix during the annealing processes.