Fabrication of 1∕4 wave plate by nanocasting lithography

Nanocasting lithography is one of the convenient ways to fabricate micronanostructures using various kinds of polymers without special tools. Nanocasting lithography is demonstrated for a 50nm half-pitch pattern, high-aspect-ratio micropillars, and high-aspect-ratio nanogratings for wave plates. The defect, which is caused by an air bubble in the sub-100nm pattern, is successfully eliminated by vacuum baking after spin coating of a polymer. Also, a high-aspect-ratio structure having 400nm pitch and 1.9μm height was successfully fabricated by polycarbonate for 2000×200μm. These structures show a 1∕5 wave shift for the 633nm wavelength.