Fluorine Containing Acryl Copolymer

ABSTRACT We are reporting on the development of acryl polymer based on novel methacrylate and acrylate monomers with varioustrifluoromethyl groups for the application to 157nm chemically amplified positive-tone resists. The a-trifluoromethylation of the alkyl ester in methacrylate or acrylate could employ the reduction of acrylpolymer absorbance at 157nm by spectra analysis with the VUV-200 spectrophotometer by JASCO. Although the trifluoromethyl groups could employ the reduction ofbase polymer absorbance at 157nm, the homopolymers have issued weak etch resistance as a photoresist base polymer. Totake account ofthis issue, we have developed a novel monomer, trifluoromethyl-iso-adamantylmethacrylate (TFIAdMA) anda new co-polymer system with the combination offluorinated methacrylate derivatives and substituted p-hydroxystyrene. Theabsorption coefficient of poly (p-tert-butoxystyren-co-hexafluoro-tert-butyl methacrylate-co-methacrylic acid) indicated tobe less than 3 tm1 at 157nm. Pattering results were obtained with a 157nm contact exposure system ofVUVES-4500 by LTJ.One ofthe experimental resists, based on a particular polymer ratio and photo acid generator, has clearly achieved 1 8Onm line