A WATER-CASTABLE, WATER-DEVELOPABLE CHEMICALLY AMPLIFIED NEGATIVE-TONE RESIST

This paper describes an ''environmentally friendly'', water-castable, water-developable photoresist system. The chemically amplified negativ e-tone resist system consists of three water-soluble components: a pol ymer, poly(methyl acrylamidoglycolate methyl ether), [poly(MAGME)]; a photoacid generator, (2,4-dihydroxyphenyl)dimethylsulfonium triflate, and a cross-linker, 1,4-butanediol. In the three-component resist syst em, the acid generated by photolysis of the photoacid generator cataly zes the cross-linking of poly(MAGME) in the exposed regions during pos texposure baking, thus rendering the exposed regions insoluble in wate r. Negative-tone relief images are obtained by developing with pure wa ter. The resist is able to resolve 1 mu m line/space features (1:1 asp ect ratio) with a deep-UV exposure dose of 100 mJ/cm(2) (dose to print ). The resist can be used to generate etched copper relief images on p rinted circuit boards using aqueous sodium persulfate as the etchant. The mechanism of cross-linking has been investigated by model compound studies using C-13 NMR.