Investigation of a fluorinated ESCAP based resist for 157 nm lithography

A survey of fluorine-containing aromatic polymers, with and without base soluble functionality, was conducted to determine their potential utility in 157 nm lithography. The focus was toward the design and evaluation of fluorine-containing polymers that closely paralleled the ESCAP matrix resins now successfully used in 248 nm photoresists. New 4-hydroxytetrafluorostyrene (HTFS) based homo-, co- and ter-polymers were prepared and evaluated for their potential utility as 157 nm resists. Significant advances were made toward reducing absorbance with fluorine substitution and monomer variation. The polymers form good films, have acceptable thermal stability and show good dry etch resistance with promising potential in thin film resist applications. The synthesis and pertinent characteristics of the new polymer systems as well as preliminary oxide etch results on representative polymers are discussed.