Fabrication of masters for nanoimprint, step and flash, and soft lithography using hydrogen silsesquioxane and x-ray lithography

A technique for fabricating masters for nanoimprint lithography, step and flash lithography, and soft lithography has been demonstrated through direct patterning of hydrogen silsesquioxane (HSQ) using x-ray lithography. Patterns that are replicated by nanoimprint, step and flash, and other soft lithographic strategies are often originally written on masters with electron beam lithography. In this article we demonstrate that if the original pattern is written with electron beam lithography to make an x-ray mask, then masters with very well-defined three-dimensional relief structures can be easily produced by direct patterning of hydrogen silsesquioxane using x-ray lithography. Direct patterning of HSQ eliminates silicon or oxide etches associated with the current fabrication techniques, providing better critical dimension and aspect ratio control of the structures on the masters. A low surface energy release agent, tridecafluoro-1,1,2,2-tetrahydrooctyl trichlorosilane, can also be applied onto the patterned HSQ to prevent the imprinted substrates from sticking to the masters. Thousands of masters can be produced from a single x-ray mask, and the x-ray mask pattern can be stepped to make large masters from a single small patterned area on the x-ray mask. The HSQ masters were successfully applied to imprint structures onto a polymeric resist substrate and poly(dimethylsiloxane).