Dry etching durability of positive electron resists

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Abstract
The effects of positive electron resist structures and G values for scission on dry etching durability have been studied with regard to plasma etching, reactive sputter etching, and plasma ashing. Polymers of aromatic methacrylates, especially poly(α‐methylstyrene), all of which contain a benzene ring in the side chain, exhibit superior durability for each etching system. On the other hand, polymers of fluorinated and chlorinated methacrylates show low durability compared with the nonsubstituted polymethacrylates. In addition, they vary in durability with respect to the etching gas used. The sputtering effect which is induced by ion bombardment in flat bed‐type reactors produces a significant loss in thickness of positive resists. Rough correlations between dry etching rates and Gs(scission) as the indication of sensitivity were obtained. The large dispersion of the correlations implies the possibility of more useful positive electron resists of high durability and high sensitivity.