Tuning the period of nanogratings using mechanical stretching and nanoimprint lithography

Abstract

We report a method to tune the nanogratings’ period using mechanical stretching and transfer the tuned gratings using a UV-curing nanoimprint process. A hybrid mold with nanogratings was stretched perpendicularly or parallel to the grating lines. The perpendicular stretching caused a continuous enlargement of the grating period, and the parallel stretching led to a continuous shrinkage of the period. As a demonstration, we tuned a grating pattern with a period of 550 nm to a wide range of periods from 450 to 750 nm. The stretched hybrid mold was used to perform a UV-curing imprint process and to transfer the tuned grating structures onto a substrate in combination with a reactive ion etching process. A larger tuning range was achieved by repeating the grating stretching and pattern transfer steps. A grating pattern with a smaller period of 140 nm was also successfully shrunk to 125 nm using this method.