Journal of Applied Polymer Science, Vol.81, No.14, 3538-3544, 2001
Preparation and characterization of copolymers containing (+)-bornyl methacrylate and their racemate for positive-tone photoresist
This study investigated the chemical behavior of polymers bearing cycloaliphatic bornyl units along with the steric difference of the chiral (+)-bornyl methacrylate [(+)-BMA] and racemic (+/-)-BMA, expressed in the physical properties of the copolymers and the resist characteristics. To do this, a series of copolymers containing (+)-bornyl methacrylate [(+)-BMA] and (+/-)-BMA] units was synthesized. Comonomers of tert-butyl methacrylate (TBMA), methyl methacrylate (MMA), and maleic anhydride (MA) were used. The thermogravimetric curves, glass-transition temperature (T-g), and molecular weight (MW) of the copolymers were evaluated. Exposure characteristics of chemical-amplified positive photoresists comprising various copolymers were investigated. It was found that copolymers bearing (+/-)-BMA have higher T-g and better thermostability than those of copolymers containing (+)-BMA units. The copolymers with (+/-)-BMA units, however, revealed an inert photochemical behavior on the positive-tone photoresist. The patterning properties of the positive photoresist, composed of copolymers bearing (+)-BMA and (+/-)-BMA, and the photoacid generator (PAG) were also investigated.