Anti-Sticking Coatings for Imprint Tools Prepared by Initiated Chemical Vapor Deposition

Abstract

Anti-sticking coatings are an integral part of imprint processes since they facilitate an effortless and defect-free demolding of stamp and imprint. A low surface energy is important for an easy and clean removal of the stamp from the imprint and for enabling a long lifetime of the expensive stamp, whereas conformality of the anti-sticking coating is important to preserve the designed structure dimensions (aspect ratio, critical dimensions, pitch size, etc.). Within this paper a branched perfluoro polyether acrylate monomer is polymerized for the first time by initiated chemical vapor deposition (iCVD) leading to a highly efficient anti-sticking coating. In appropriate conditions, iCVD can produce thin conformal polymer coatings whose mechanical and chemical stability can be significantly improved by tuning the cross-linking density. The coating is furthermore grafted by covalent bonds via a self-assembled monolayer onto the substrate – i.e., the nickel stamp – in order to prevent delamination. As a result, the coating delivers a water contact angle of 109°, more than 80° higher than for the uncoated and cleaned Ni-sample, i.e. 73% WCA reduction, and more than 50° higher than for the uncleaned Ni sample that is stored at ambient condition (i.e. 46% WCA reduction). Long-term imprint tests confirm the durability of the anti-sticking property on the Ni-stamp.