Etching characteristics of diamond-like carbon in fluorocarbon plasmas

Abstract

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.