Enhancing the adhesion of diamond-like carbon films to steel substrates using silicon-containing interlayers

Diamond-like carbon (DLC) films were deposited on AISI 316L stainless steel by using a unipolar pulsed-DC plasma assisted chemical vapor deposition (PACVD) system. In order to improve the adhesion of the DLC films to the substrate, three different silicon-containing interlayers (a-Si:H, a-SiCx:H, and a-SiNx:H) were deposited at two temperatures of 150 and 350 °C using silicon tetrachloride, methane, nitrogen, and hydrogen precursors. The DLC films with silicon-containing interlayers, deposited at 150 °C, did not show appropriate adhesion to the substrate due to the presence of a high amount of chlorine and hydrogen in the structure of the interlayers. By increasing the temperature of the interlayer deposition, the adhesion of DLC films improved significantly. The results of Raman spectroscopy, Nano indentation and adhesion tests showed that the DLC film with a-SiNx:H interlayer exhibited the lowest ID/IG ratio, highest hardness, and highest adhesion to the substrate.