Transparent and visible light-insensitive acrylic photoresist for negative tone optical lithography

The study presented in this paper describes an optimized negative tone optical resist based on ultraviolet (UV)-induced cross-linking of polymethyl methacrylate (PMMA). This simple resist is made by dissolving PMMA and a photo-cross-linking agent—Irgacure 379, in ethyl lactate. Irgacure cross-links PMMA when exposed to i-line radiation (365 nm wavelength). However, as it does not absorb at longer wavelengths, this resist is in-sensitive to...