Seung Hyun Ra

Nano sized patterning on the thermoset materials using thermal curing nano-imprinting technology

Nano-imprinting technology, currently developing as an alternative technology for photolithography, is mostly dealing with photo resist materials for etching barrier. In other words, the materials imprinted are used as the barriers for wet etching or RIE (reactive ion etching), and then are removed after all. Thus, most materials developed for nano-imprinting technology have relatively low Tg(<100oC), in case of solids or have a low viscosity before curing in order to fill the gap of the stamp. Such materials could not be suitable for the structures that require relatively high temperature process ability, high modulus or high durability. Epoxy is one of candidates that meet such requirements for the structures. However, it has not been reported about imprinting on epoxy materials. In this paper, nano-imprinting technology was developed to fabricate the microstructures. Instead of thermoplastic imprint resin, solid phase epoxy films, which is thermoset polymer, were imprinted with SAM (self assembly monolayer) coated quartz and silicon stamps. Feature size of stamp varies from 150nm to 1 μm and height was 300nm for quartz stamp and 3μm for Si stamp.

Embossing Lithography on Sticky Thermoset Polymer Using Ni Template

Embossing lithography is one of the most promising technologies for mass production of nano-scale structures. To advance the industrialization of embossing lithography, fabrication of low cost, high mechanical strength embossing template is essential. Electroformed Ni template can be used as an embossing template if its poor anti-adhesive property is fixed by proper releasing layer treatment, especially, when it is used with sticky thermoset polymer. In this experiment, quartz master template with 200nm to 2um sized surface protrusions was fabricated and used to emboss the PMMA coated Si wafer. Then the embossed PMMA layer was coated with metal seed layer (Ni) and electroplating of Ni was followed to fabricate Ni template. To apply anti-stiction SAM layer, SiO2 and Si layer was coated on Ni template. With proper anti-stiction treatment of Ni template, sub-micron patterns were successfully transferred to sticky thermoset polymers such as epoxy resin using Ni template without any degradation of anti-adhesive property.