Engineering Silk Protein to Modulate Polymorphic Transitions for Green Lithography Resists
Soon‐Chun Chung, Joon-Song Park, Rakesh Kumar Jha, Jieun Kim, Jinha Kim, Muyoung Kim, Juwan Choi, Hongdeok Kim, Dahye Park, Narendar Gogurla, Tae‐Yun Lee, Heonsu Jeon, Ji‐Yong Park, Joonmyung Choi, Ginam Kim, Sunghwan Kim
Abstract
Silk protein is being increasingly introduced as a prospective material for biomedical devices. However, a limited locus to intervene in nature-oriented silk protein makes it challenging to implement on-demand functions to silk. Here, we report how polymorphic transitions are related with molecular structures of artificially synthesized silk protein and design principles to construct a green-lithographic and high-performative protein resist. The repetition number and ratio of two major building blocks in synthesized silk protein are essential to determine the size and content of β-sheet crystallites, and radicals resulting from tyrosine cleavages by the 193 nm laser irradiation induce the β-sheet to α-helix transition. Synthesized silk is designed to exclusively comprise homogeneous building blocks and exhibit high crystallization and tyrosine-richness, thus constituting an excellent basis for developing a high-performance deep-UV photoresist. Additionally, our findings can be conjugated to design an electron-beam resist governed by the different irradiation-protein interaction mechanisms. All synthesis and lithography processes are fully water-based, promising green lithography. Using the engineered silk, a nanopatterned planar color filter showing the reduced angle dependence can be obtained. Our study provides insights into the industrial scale production of silk protein with on-demand functions.