Aqueous base developable deep uv resist systems based on novel monomeric and polymeric dissolution inhibitors

Abstract

Certain “onium salt” photochemical acid generators such as triphenylsulfonium and diphenyUodonium metal halides work as dissolution inhibitors for novolac resins in a fashion similar to diazonaphthoquinone. The two-component deep UV positive resists can be imaged in an aqueous base at 25 mJ/cm2 of 254 nm radiation. The system allows addition of a third component. For example, polyphthalaldehyde, a novel and efficient dissolution inhibitor miscible with novolac resins, is completely reverted to the starting monomer in the novolac matrix upon postbake. The design is based on removal of the polymeric dissolution inhibitor from the exposed areas through acid-catalyzed depolvmerization to volatile monomer. Such three-component resist systems offer high deep UV sensitivity (2 mJ/cm2), high contrast (4.2), and wide formulation and process latitudes. © 1988 SPIE.