ALICYCLIC POLYMERS FOR 193 NM RESIST APPLICATIONS - LITHOGRAPHIC EVALUATION

Photoresist compositions designed for 193 nm lithography were formulat ed from a series of cycloaliphatic co- and terpolymers of 2-methylprop yl bicyclo[2.2.1]hept-5-ene-2-carboxylate (trivial name, carbo-tert-bu toxynorbornene), bicyclo[2.2.1]hept-2-enecarboxylic acid (trivial name , norbornene carboxylic acid), carboxytetracyclo[4,4,0.1,(2,5)1(7,10)] dodec-3-ene (trivial name, methyltetracyclododecene carboxylic acid), 5-norbornene-2-methanol, and maleic anhydride, which were synthesized by free radical, Pd(II)-catalyzed addition and ring-opening metathesis polymerization techniques. The cycloaliphatic polymer backbones provi de etch resistance, mechanical properties, and stability to radiation. The lithographic function is provided by carefully tailored pendant g roups, which include an acid functionality that is masked by protectin g groups that undergo acid-catalyzed thermolysis, as well as polar gro ups that influence the adhesion, wettability, and dissolution properti es of the polymer. The polymers are soluble in common organic solvents and have glass transition temperatures ranging from less than 60 degr ees C to higher than 250 degrees C depending on the specific structure and mode of polymerization. The polymers are as transparent at 193 nm as the corresponding acrylics. The dry etch resistance of these polym ers varies with the formulation, but the polymers etch more slowly tha n APEX-E, a commercial deep UV photoresist under conditions typically used to pattern polysilicon. Upon exposure and baking, the resists hav e demonstrated high sensitivities (3-15 mJ/cm(2)), and 0.16 mu m featu res have been resolved.