Nondestructive Demolding of Structure-Designable High-Aspect-Ratio\nNanoimprint Template

Demolding\nis a crucial step in nanoimprint lithography (NIL) for\nsuccessfully transferring template structures onto resist materials.\nThe process, however, is often hindered by the adhesion and friction\nbetween the template and resist, leading to inevitable defects on\nthe replicas and posing challenges in replicating templates with high-aspect-ratio\n(HAR) structures. Here, we introduce a novel approach using the dissolvable\ntemplate method to achieve the nondestructive demolding of structure-designable\nHAR nanoimprint templates. The templates were fabricated by the 3D\nlithography technology, employing a positive photoresist that can\nbe easily dissolved in alkaline solutions after exposure to ultraviolet\n(UV) radiation. By implementing this method, we successfully transferred\ndense arrays of pillars with a minimal diameter of 1.2 μm and\na significant aspect ratio of 18, as well as a microlens array diffuser\nwith randomly distributed structural parameters. The dissolvable template\nmethod paves the way for stress-free demolding, broadening NIL’s\napplication range.