Sol–gel behavior and image formation in poly(glycidyl methacrylate) and its copolymers with ethyl acrylate

Abstract

For the formation of rather large features (≳5 μm on a side) in poly(glycidyl methacrylate) and its copolymers with ethyl acrylate, the lithographic response can be characterized by a gel‐point energy and a contrast. The gel‐point occurs at 6.8 eV absorbed energy per molecule of homopolymer or of its effective equivalent in the copolymer. The contrasts of these negative resists are dynamic properties, but depend in part on the polymer’s dispersitivity, at least to a value 2.3. As features are progressively reduced, the gel‐point advances to higher dose and the contrast increases. These new parameters correlate poorly with the molecular parameters of the polymers; they depend instead on developer‐induced swelling of the image, on competitive wetting of the support layer by the developer and the polymer and on gel‐rupture by forced development.