A simple lithographic method employing 172 nm vacuum ultraviolet light to prepare positive- and negative-tone poly(methyl methacrylate) patterns

We successfully prepared both positive- and negative-tone patterns by applying poly(methyl methacrylate) (PMMA) as a photoresist. A positive-pattern was prepared by lithography through a photomask using 172 nm vacuum ultraviolet (VUV) light under the pressure of 10³ Pa. A negative-pattern was prepared using the same VUV light under the reduced pressure of 10 Pa, followed by rinsing with toluene solution. At 10³ Pa, the irradiated PMMA was effectively decomposed and eliminated. On the other hand, at 10 Pa, the irradiated PMMA became cured and resistant to etching. We subsequently utilized these positive- and negative-tone patterns as templates on indium-tin-oxide surfaces to electrodeposit copper microstructures with 10 μm lines and spaces.