Etching characteristics of diamond-like carbon in fluorocarbon plasmas

Diamond-like carbon (DLC) is one of the promising materials with biocompatibility. Applications for medical coating, biochip, and so on, have been widely expected in this decade. Fabrication process of biochips such as etching and removing requires patterning of the DLC to give surface of the chips functions for medical diagnostics. The present study reports etching characteristics of the DLC in fluorocarbon plasmas, comparing with those of Si and SiO2. In the plasmas, F radical was found to be an etchant for the DLC, the same as etching of Si and SiO2. The O radical is well known to be so reactive on the DLC. The O2-addition to the plasmas was obviously effective in the DLC etching, and making balance of the radicals of F and O, resulting in changing etch rate of the DLC and morphology of surface. The etch rate could be controlled in changing gas flow rate of CF4 to O2 with Ar dilution. The morphology, which is indispensable to determine the characteristics on the surface of the biochip and so on, showed that fluorine-content plasmas suppressed roughness compared with pure-O2 plasmas.