Studies On Cationic Nanoimprint Resist And Composite Mold

Compare with photo lithography, nanoimprint lithography is a sub-5nm resolution, high-throughput, low-cost pattern transfer technique. As the one of most active technologies in micro-and nano-fabrication filed in the past10years, nanoimprint lithography has been found numerous applications in nanoelectronic devices, bio-chips, high-capacity disks and optical elements.Nanoimprint resist、nanoimprint mold and nanoimprint machine, as the three key elements, were studied by a lot of researchers for a long time. In this article, we developed a UV-curing nanoimprint resist based on cationic polymerizable epoxysiloxane and invented a sandwiched composite nanoimprint mold.Most of the UV-curable nanoimprint resists currently used are based on free radical polymerization of highly reactive acrylate monomers and oligomers, but they have a shortage that the oxygen in the air can inhibit their polymerization. A series of epoxysiloxane oligomers were designed and synthesized via hydrosilylation of4-vinyl-cyclohexane-1,2-epoxide with poly(methylhydrosiloxane) with tunable viscosity and crosslinking density. The resist exhibits excellent properties such as insensitivity toward oxygen, strong mechanical strength and high etching resistance. Using this resist, nanoscale patterns of different geometries with feature sizes as small as30nm were fabricated via a UV-curing nanoimprint process The resist can also be thermal-cured in10s at a moderate temperature with the help of UV light pre-exposure. Particle related defects are of key concern since nano imprint is a physical contact process. The particle will amplify the defect much larger than the particle itself. To solve this problem, we invented a sandwiched tri-layer composite mold for large-scale nanoimprint. The low-cost, durable mold consists of three parts:an elastic buffer layer sandwiched between a stiff feature partand a PET support. The particle induced defectivity could be dramatically improved by the deformation of the PDMS cushion layer with applying a slight external pressure. The imprinting results indicated that the mold had capabilities to tolerate dense particles and adapt to the wavy surface.