High resolution templates for step and flash imprint lithography

Step and Flash Imprint Lithography (SFIL) is an attractive method for printing sub-100 nm geometries. Relative to other imprinting processes SFIL has the advantage that the template is transparent, thereby facilitating conventional overlay techniques. In addition, the imprint process is performed at low pressures and room temperature, minimizing magnification and distortion errors. The purpose of this work was to investigate alternative methods for defining high resolution SFIL templates and study the limits of the SFIL process. Two methods for fabricating templates were considered. The first method used a very thin (< 20 nm) layer of Cr as a hard mask. The second fabrication scheme attempts to address some of the weaknesses associated with a solid glass substrate. Because there is no conductive layer on the final template, SEM and defect inspection are compromised. By incorporating a conductive and transparent layer of indium tin oxide (ITO) on the glass substrate, charging is suppressed during SEM inspection, and the transparent nature of the final template is not affected. Using ZEP-520 as the electron beam imaging resist, features as small as 20 nm were resolved on the templates. Features were also successfully imprinted using both types of templates.