Multilevel Hierarchical Topographies by Combined Photolithography and Nanoimprinting Processes To Create Surfaces with Controlled Wetting

Abstract

This work presents a practical methodology to produce multilevel hierarchical structures with precise control of the structural geometry at every level by combining photo and nanoimprint lithography processes. The method involves sequential steps of nanoimprinting of a first deposited polymer layer followed by nanoimprinting of a second deposited layer of a photoresin and, afterward, performing on this layer optical lithography by means of a maskless laser writer to pattern micrometer-size features. A hierarchical topography is consequently obtained comprising nanopatterns and micropatterns at different levels designed independently with very high feature control. The process can be repeated sequentially employing hierarchical working molds produced on a previous fabrication cycle to produce multilevel self-similar hierarchical topographies in a sort of fractal growing manner. The patterning method has broad applicability, as exemplary demonstration, superhydrophobicity, and anisotropic wetting behavior are revealed.