| Nanoimprint lithography with ultra violet (UV) curing of the resist, known as step-and-flash lithography, requires the mold substrate to be transparent to the UV light, due to the evident fact that the UV light must have a path to reach the resist in between the mold and the sample substrate. Various types of glass, such as quartz or borofloat, are widely used as a mold substrate material. The most conventional method of fabricating sub-micro sized patterns is using e-beam lithography. However, the biggest drawback of using glass substrate is the fact that they are not conductive, which requires an extra fabrication process to deposit a conducting layer, which makes the process difficult and expensive. In this work, an effective, simple, and cost-effective UV-Nanoimprint mold fabrication technique has been developed using a UV transparent polymer based on PMMS. The polymer mold is replicated from a master mold using UV-curing, treated with an anti-adhesion surfactant to reduce stiction, and then used in imprinting. The replicate polymer mold is shown to maintain the same morphological details of the master mold. The pattern transfer from the replicate polymer mold to the resist on a silicon substrate is shown to be possible down to the 50-nm size. Using AFM analysis, successfulness of the novel replicated polymer mold is validated.;Utilizing this material, an effective and simplified method of fabricating a three-dimensional (3D) polymer woodpile structure for photonic crystal application is developed. The polymer material is patterned directly by UV-based nanoimprint lithography (UV-NIL), where a novel layer-by-layer technique is used. Demonstration of three layers of the woodpile structure is shown. Height analyses of each layer have shown that successful pattern transfer has been performed. |
