Large size seamless nano patterned molder using direct laser writing

摘要

A cylindrical molder with nano or micro patterns on it is a key component of the roll to roll (R2R) process, which replicates patterns continuously on a substrate such as a polycarbonate (PC) film. Generally, a molder which has a several tens of micro size is manufactured through machining process, but a molder which has nano size patterns of 1 micrometer or less is particularly difficult to manufacture without seams. In the past research, we proposed a method of fabricating a large size polymer nano patterned substrate using nanoimprint and a large size metal flat molder using electroplating process. A cylindrical roll molder will be fabricated by winding the flat metal molder around a cylindrical body. Although this molder has seams, we have shown a way to produce a metal cylindrical molder that is easy to maintain and cost competitive. However, in order to apply it to actual industries, it is necessary to eliminate seams on a molder surface or minimize the seam area as much as possible. In this study, we propose a method to fabricate a nano patterned substrate whose size is 110mm × 110mm or more using two photon polymerization (TPP) direct laser writing (DLW). This method is able to minimize the seam area of a metal molder dramatically. The DLW system is comprised of a Ti:sapphire femtosecond laser with 800nm wavelength for a processing beam and piezo and long stroke linear stages with nanometer resolution. The autofocus unit which is the key function for large area patterning is designed based on a astigmatism principle with a 600nm wavelength laser, and we succeeded in fabricating a nanopattern substrate with a minimum pattern size of 200nm or less using an ormocomp based resin.