Extracted natural silk fibroin as a dual-tone protein resist for eco-friendly electron beam lithography

Abstract

We report on the ability to reshape extracted natural silk fibroin with energetic electrons and on the application of advanced spectroscopic imaging for nanoscale structural analysis. Silk fibroin films under electron irradiation at various exposure dosages have been investigated using infrared scattering near-field optical microscopy (s-SNOM) for the first time to decipher the electron-regulated structural transitions of silk fibroin, which determines its solubility in water. Our work provides important guidelines for utilizing silk fibroin as a dual-tone protein resist for all-water-based eco-friendly electron beam lithography (EBL), with no hazardous chemicals used or generated in this process.