PROCESSES OF TOP-IMAGED SINGLE-LAYER RESISTS BY POTASSIUM-ION TREATMENT IN SOLUTION

Abstract

This paper presents new processes for the enhancement of oxygen reactive ion etching (RIE) resistance of two single-layer resist systems by selective incorporation of potassium ions into the resist image in solution after exposure. One resist system is diazonaphthoquinone (DAQ) and poly(p-formyloxystyrene) (PFS) mixed with a catalytic amount of triphenylsulfonium hexafluoroarsenate as a photoacid generator. After deep-UV exposure, the photoacid catalyzes the photo-Fries rearrangement of PFS to form poly(p-hydroxystyrene) (PHS); DAQ rearranges to form indene carboxylic acid and grafts into PHS via S-O bond formation. A latent image is formed by selective reaction of carboxylic groups with C5H11COOK in aqueous solution in exposed areas which are resistant to oxygen RIE. Dry developed negative-tone patterns are obtained by oxygen RIE. The other resist system is AZ1350J, dipping in C23H47COOK in hexane after deep-UV exposure. C23H47COOK selectively incorporates into unexposed areas only. Dry developed positive-tone patterns are obtained by oxygen RIE in this case.