Mitigation of microloading effect in nanoimprint mask fabrication

The impact of microloading on photomask etch has been widely studied in the last decade; microloading results in differing etch depths for different pattern resolution and densities. Techniques used to reduce microloading in photomask etch cannot always be directly extended to nanoimprint masks. In nanoimprint mask fabrication, the effects of litho and etch are more critical because of the 1:1 reproduction of features on the mask. Also, to keep the imprint mask cost low, simpler processes are preferred. The proposed technique uses grayscale lithography to reduce the microloading effect. The proposed process is modeling intensive but repeatable and requires no extra process steps.