Improved step and flash imprint lithography templates for nanofabrication

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, which minimizes magnification and distortion errors. Several different methods for fabricating templates are presented in this study. One scheme addresses some of the weaknesses associated with a solid glass substrate by incorporating a conductive and transparent layer of indium tin oxide (ITO) on the surface of the substrate. Features are defined on the templates by patterning a thin layer of PECVD oxide that is deposited on the ITO layer. A second method bypasses the oxide etch process by imaging a thin layer of hydrogen silsesquioxane (HSQ). By using a combination of these two methods, it is also possible to form multi-tiered structures on a template. Templates with features as small as 20 nm have been fabricated using the methods described above. The templates were then used to imprint patterns on 200 mm silicon wafers. It appears that any feature defined in the template is faithfully replicated on the wafer.