Effect of fluoroalkyl substituents on the reactions of alkylchlorosilanes with mold surfaces for nanoimprint lithography

Abstract

We have applied trichloro(3,3,3-trifluoropropyl)silane (FPTS) and trichloro(1H,1H,2H, 2H-perfluorooctyl)silane (FOTS) for the preparation of self-assembled film on a silicon mold for use as releasing, antisticking layers for nanoimprint lithography. From contact angle measurements, we have determined the surface energies of the molds in terms of their Lewis acid, Lewis base, and van der Waals components. The surface energies of the FPTS- and FOTS-derived film decreased as the annealing temperature and immersion time increased. Suitable self-assembled films were prepared by annealing at 150°C for at least 1h. The surface roughnesses of the self-assembled film formed from FPTS and FOTS were 0.468 and 0.189nm, respectively. The lower surface energy and roughness of the FOTS-derived film on the silicon mold prevent both the adhesion and defect-formation problems from occurring during resist imprinting. The self-assembled films prepared on the mold are resistant to immersion in acid and base, but treatment with oxygen plasma has an adverse effect on these molds’ stabilities.