Template fabrication schemes for step and flash imprint lithography

Abstract

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. The purpose of this work is to investigate alternative processes for defining features on an SFIL template. The first method considered using a much thinner (<20 nm) layer of Cr as a hard mask. Thinner layers still suppress charging during e-beam exposure of the template and have the advantage that CD losses encountered during the pattern transfer through the Cr are minimized. The second fabrication scheme addresses 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 on the glass substrate, charging is suppressed during inspection and the UV characteristics of the final template are affected minimally. Templates have been fabricated using the two methods described above. Features as small as 30 nm have been resolved on the templates. Sub-80 nm features were resolved on the first test wafer printed.