Fabrication of a seamless roller mold with wavy microstructures using mask-less curved surface beam pen lithography

Roller imprinting is one of the most commonly used methods for the fabrication of continuous functional structures over large areas. However, the fabrication of roller molds with seamless and complex patterns poses a significant challenge. This paper presents an innovative technique for fabricating a seamless roller mold with wavy microstructures using a novel mask-less curved surface beam pen lithography technique. The major steps in the proposed technique include spray coating a thin photo-resist (PR) layer on the roller, exposing the PR layer though a translating micro-lens array (MLA), etching the patterned PR layer, and electro-polishing the etched microstructures. The proposed method is used to pattern roller molds with different wavy microstructures by varying the rotation speed of the roller, the translation speed of the MLA holder, and the translation distance of the MLA holder. The patterned metal roller molds are then used to replicate wavy microstructures on a thin polyethylene terephthalate substrate by means of continuous UV-type roller imprinting methods. The line-width and height of the wavy microstructure are 84.5 mu m and 25.5 mu m, respectively.