Silk Fibroin as a Photoresist in Lithography
Tufts University investigators have developed a lithography resist that eliminates minimizes the use of harsh chemicals without sacrificing resolution. Optical-grade silk fibroin aqueous solution obtained from the cocoons of the Bombyx mori caterpillar is placed on a substrate and spin-coated to form a silk film.
Eliminates special wastewater treatment
For positive resist work the film is crosslinked, but for negative resist, this step is skipped and the film is left in its uncrosslinked state. Electron-beam exposure on selected areas either crosslinks or de-crosslinks silk fibroin molecules. Water can then be used to wash away the water-soluble (uncrosslinked) areas.
• IC circuits
• MEMS devices
• Flexible electronics – sensors and IC circuits
Photoresists (novolak resins) used in lithography for the fabrication of ICs and MEMS devices are known carcinogens requiring special equipment to treat wastewater.
Competitive Advantage. The resist is a biocompatible and biodegradable biopolymer allowing more economical wastewater treatment and minimizes health risks.
US Publication No. 2016-0033861 (Published February 2, 2016)