Polycarbonate electron beam resist using solvent developer

Polycarbonate is a popular membrane material fabricated by ion track etching method and used for filtration, thus it is a sort of ion beam resist. Here we show that it can also be used as a positive electron beam resist using solvent development. Compared to the popular resist PMMA, polycarbonate is more chemically and thermally stable, and is more resistant to plasma dry etching. Various solvents, including cyclopentanone, xylene, pentyl acetate and methyl isobutyl ketone, were found to be suitable developers for polycarbonate when diluted properly with 2-propanol. The resist showed a low contrast between 0.5 and 1.0 when using those solvent developers, and thus it is not a good resist for defining high resolution dense patterns, yet is ideal for grayscale lithography to generate quasi-three dimensional structures like Fresnel zone-plate lens. Nevertheless, we achieved sub-50 nm resolution for sparse line array pattern. (C) 2013 Elsevier B.V. All rights reserved.