Towards environmentally friendly processing of ionic liquid-based photoresists with a boosted lithography performance

Abstract

The development of a sustainable process for producing high-performance photoresists is desirable yet challenging. In this study, we proposed an ionic liquid (IL)-assisted approach for preparing a photoresist by copolymerizing 1-butyl-3-vinyl imidazolium bromide (VBIMBr) and acrylates. The hydrophilic nature of VBIMBr improved the adhesion between the photoresist and the hydrophilic Si substrate, eliminating the use of hazardous hexamethyldisilazane (HMDS) vapor. This IL-based photoresist could be developed with water instead of the corrosive developer tetramethylammonium hydroxide (TMAH). Furthermore, the interaction between VBMIBr and H⁺ effectively reduced acid diffusion and line edge roughness (LER), resulting in superior lithography performance compared to traditional acrylate photoresists. This IL-based photoresist exhibited an excellent response to both deep ultraviolet lithography (DUV) and electron beam lithography (EBL), achieving a line resolution of 0.5 μm and 100 nm, respectively. Meanwhile, the lithography kinetics and mechanism were further investigated. Overall, this eco-friendly IL-assisted strategy provides a promising solution for producing high-performance photoresists, even in electrical applications. Additionally, this IL-assisted approach has the potential for widespread use in the development of advanced materials.