Geometrical properties of multilayer nano-imprint-lithography molds for optical applications

The functionality of micro- and nano-optical devices can be increased by using three-dimensional structures instead of two-dimensional ones. This paper reports on a fabrication method for nano-imprint lithography molds for planar optical applications which exhibit two different height levels with large pattern diversity as various lithographic technologies can be applied. To ensure a proper operation of optical elements as waveguides, a precise control of the feature dimensions is essential. The lateral and depth resolution as well as the alignment of two structure height levels have been investigated. The results show the feasibility of the process to obtain single-mode operating waveguides and micro-ring resonator structures for sensor applications. The replication of these structures has been performed in a UV-curable polymer. A residual layer could be avoided using non-wetting perfluoropolyether polymer molds cast from the original ones used in a reverse nano-imprint setup. (C) 2012 Elsevier B.V. All rights reserved.