Fabrication of fluorine-doped diamond-like carbon stamps for UV nanoimprint lithography

Two fluorine-doped diamond-like carbon (F-DLC) stamps with sub-100 nm line patterns were fabricated using a direct etching method. These were applied successfully to ultraviolet (UV) nanoimprint lithography without requiring an anti-adhesion layer coating. Tests were performed to determine the optimum fluorine concentration for the F-DLC stamps. The ideal stamp material consisted of 25 at.% F-DLC with a contact angle of 85°, UV transmittance of 16.4–26.8%, and hardness of 4.5 GPa. The O₂ plasma etch rate of the DLC was increased considerably by the fluorine doping, making it comparable to the etch rate of polymethyl methacrylate (PMMA). Thus, only PMMA was used as the etch mask in the fabrication of the stamps.