Effect of Polymer Substrates on Nano Scale Hot Embossing

Abstract

ABSTRACTHot embossing has been widely accepted as an alternative to photolithography in generating patterns on polymer substrates. The optimization of embossing process should be accomplished based on polymer surface properties. Therefore, in this paper, polymers with different surface characteristic were selected and the surface properties of each polymers such as surface energy and adhesion force were investigated by contact angle and AFM. Based on these results, the imprinted nano patterns were compared. Silicon molds with nano size patterns were fabricated by e-beam direct writing. Molds were coated with self-assembled monolayer (SAM) of (1, 1, 2, 2H –perfluorooctyl)-trichlorosilane to reduce the stiction between molds and polymer substrates. For embossing, pressure of 500 psi, embossing time of 5 min and temperature of above transition temperature were applied. Mr-I 8010 polymer (Micro Resist Technology), Polymethylmethacrylate (PMMA 495k) and LOR (polyaliphatic imide copolymer) were used as substrate for hot embossing process development in nano size. These polymers were spun coated on the Si wafer with the thickness of 150 nm. The nano size patterns obtained by hot embossing were identified by atomic force microscopy without breaking the pattern and compared based on the polymer surface properties. The mr-I 8010 which has the lowest surface energy and adhesion force shows the best demolding property.