Multilayer Nanoimprinting to Create Hierarchical Stamp Masters for Nanoimprinting of Optical Micro- and Nanostructures

Abstract

Nanoimprinting is a well-established replication technology for optical elements, with the capability to replicate highly complex micro- and nanostructures. One of the main challenges, however, is the generation of the master structures necessary for stamp fabrication. We used UV-based Nanoimprint Lithography to prepare hierarchical master structures. To realize structures with two different length scales, conventional nanoimprinting of larger structures and conformal reversal nanoimprinting to print smaller structures on top of the larger structures was performed. Liquid transfer imprint lithography proved to be well suited for this purpose. We used the sample prepared in such a way as a master for further nanoimprinting, where the hierarchical structures can then be imprinted in one single nanoimprinting step. As an example, we presented a diffusor structure with a diffraction-grating structure on top.

Nanoimprinting of Biomimetic Nanostructures

“…Nanoimprinting is able to perform single-step patterning of multilevel or hierarchical patterns or patterns with very different dimensions. If the right stamp (and master) is avail-able it is possible to fabricate in a single imprinting step structures of very different lateral dimensions [14,15], of different vertical dimensions with multiple height levels [16][17][18], or curved surfaces [19] and hierarchical structures [14,[20][21][22]. It is also possible to perform nanoimprinting on complex curved objects [23][24][25][26].…”

“…This pattern was then used as a master for stamp fabrication to be able to imprint the complex pattern in one single imprinting step. Details can be found in reference [14].…”

“…This pattern was then used as a master for stamp fabrication to be able to imprint the complex pattern in one single imprinting step. Details can be found in reference [14]. From Left to Right: the stamp is brought in close vicinity of the substrate, which is coated with a UV-curable resin (imprint material), before bringing it into direct contact with the substrate.…”

Nanoimprint Replication of Biomimetic, Multilevel Undercut Nanostructures

“…Due to the fact that nanoimprinting can—in a single process step—replicate complex multilevel structures [ 1 , 24 , 27 , 28 ], it is ideally suited for the replication of such biomimetic or bio-inspired nanostructures. A big challenge for nanoimprinting, however, is the replication of undercut features, since it is usually not possible to remove the stamp from such features, especially if they are of nanoscale.…”

Mastering of NIL Stamps with Undercut T-Shaped Features from Single Layer to Multilayer Stamps

“…With an imprint stepper or with roll-to-roll NIL also large areas can be patterned three-dimensionally. For fabrication of three-dimensional structures hybrid structuring processes combining NIL and electron beam lithography [ 19 , 20 ] or NIL and photolithography [ 21 ], as well as multilayer nanoimprinting [ 22 ] to create hierarchical stamp masters for optical micro- and nanostructures have been recently demonstrated successfully. Even imprinting of complex three-dimensional nanomolds [ 23 ] was successfully demonstrated.…”