Antisticking layers on antireflective chromium for hybrid (CNP) nanoimprint molds

Combined nanoimprint and photolithography (CNP) is an attractive imprint technology for residual layer free direct patterning of high aspect ratio polymer structures. Employing the chromium hard mask from the imprint mold etching process as a light blocking metal layer on top of the imprint mold protrusions is an efficient manufacturing method for CNP molds. The surface chemistry of the mold and in particular of the chromium layer is crucial for the realization of antisticking layers (ASLs) on suchlike CNP molds. For the reported ASL coatings, the stripping process of the electron beam resist was very important, especially for fluorinated resists. We compared an antireflective chromium photomask surface with the standard imprint mold materials Si (native oxide), SiO2 (thermal oxide) and quartz. Low surface free energies of ~15.3mN/m and ~10.9mN/m were achieved by chemical vapor deposition of 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) for the chromium surface and the natively oxidized Si, respectively. The ASLs were successfully tested on unstructured chromium imprint molds without sticking problems during imprinting.