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 50 nm 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-100 nm pattern, is successfully eliminated by vacuum baking after spin coating of a polymer. Also, a high-aspect-ratio structure having 400 mn pitch and 1.9 mu m height was successfully fabricated by polycarbonate for 2000 X 200 mu m. These structures show a 115 wave shift for the 633 nm wavelength. (c) 2005 American Vacuum Society.