No abstract

The feasibility of using hydrogen silsesquioxane (HSQ) to directly pattern the relief layer of step and flash imprint lithography (SFIL) templates has been successfully demonstrated. HSQ is a spin-coatable oxide, which is capable of high resolution electron-beam lithography. Negative acting and nonchemically amplified, HSQ has moderate electron-beam sensitivity and excellent processing latitude. In this novel approach, 6 ×6 × 0.25 in.3 quartz photomask substrates are coated with a 60 nm indium tin oxide (ITO) charge dissipation layer and directly electron-beam written using a 100 nm film of HSQ. Direct patterning of an oxide relief layer eliminates the problems of critical dimension control associated with both chromium and oxide etches, both required processes of previous template fabrication schemes. Resolution of isolated and semidense lines of 30 nm has been demonstrated on imprinted wafers using this type of template. During this evaluation, a failure of the release layer to provide a durable nonstick surface on ITO was discovered and investigated. This problem was successfully remedied by depositing a 5 nm oxide layer over the patterned ITO/HSQ template.

Previous work with the mechanical properties of step and flash imprint lithography etch barrier materials has shown bulk volumetric shrinkage trends that could impact imprinted feature dimensions and profile. This article uses mesoscopic and finite element modeling techniques to model the behavior of the etch barrier during polymerization. Model results are then compared to cross section images of template and etch barrier. Volumetric shrinkage is seen to impact imprinted feature profiles largely as a change in feature height.