Thiol-yne Photo-curable Hybrid Resist: An Alternative for UV Nanoimprint Lithography (UV-NIL)

Abstract

We here designed a new hybrid resist for UV-NIL based on the thiol-yne photopolymerization. The hybrid resist is comprised of bifunctional polyhedral oligomeric silsesquioxane containing octyl and mercaptopropyl groups (POSS-OA-SH) and difunctional alkyne. The obtained hybrid resists possess numerous desirable characteristics for UV-NIL, such as great coating ability, high thermal stability, low surface-energy, low bulk volumetric shrinkage (0.8~4.8%), and excellent oxygen-etch resistance. Because of the click reaction characteristics of thiol-yne photopolymerization, the hybrid resists can be photo-cured within seconds under UV exposure at room temperature. Finally, through the double-layer resist approach for pattern transfer onto silicon substrate, the transfer pattern with the height of about 3 times more than that of the original NIL pattern can be obtained due to excellent oxygen-etch resistance of the etch barrier material. These results provide the thiol-yne hybrid resists as an alternative for UV-NIL.

Progress in Polyhedral Oligomeric Silsesquioxane (POSS) Photoresists: A Comprehensive Review across Lithographic Systems

“…Moreover, it enables the attainment of pattern resolutions in the range of 100 nm to several microns when exposed to UV light-a capability well-suited for supporting the etching process in UV-NIL [82]. Drawing inspiration from thiol-alkene click chemistry principles, Lin H. et al [83] introduced a mixed photoresist of thiol-alkynes in 2014, offering another avenue for designing UV-NIL photoresists. Illustrated in Figure 12, this approach involved the use of four-substituted mercaptopropyl POSS to engage in a light-click reaction with alkynes, yielding hybrid materials with a degree of cross-linking.…”

“…When polystyrene (PS) is employed as the transfer membrane, the original polymer's height is preserved. Drawing inspiration from thiol-alkene click chemistry principles, Lin H. et al [83] introduced a mixed photoresist of thiol-alkynes in 2014, offering another avenue for designing UV-NIL photoresists. Illustrated in Figure 12, this approach involved the use of four-substituted mercaptopropyl POSS to engage in a light-click reaction with alkynes, yielding hybrid materials with a degree of cross-linking.…”