New single layer positive photoresists for 193 nm photolithography

New series of chemically amplified, single layer. positive tone photoresists for 193 nm lithography have been developed. These resists were formulated from a series of cycloaliphatic co- and terpolymers of 2-methyl propyl bicyclo[2.2.1]hept-2-ene-5-carboxylate (carbo-tert-butoxynorbornene), bicyclo[2.2.1]hept-2-ene carboxylic acid (norbornene carboxylic acid), 8-methyl-8-carboxy tetracyclo[4,4,0.1(2,5),1(7,10)]dodec-3-ene (methyltetracyclododecene carboxylic acid), norbornenemethanol, and maleic anhydride, which were synthesized by free radical, vinyl addition and ring opening metathesis polymerization techniques, Thc polymers derived fb om ring opening metathesis polymerization have been successfully hydrogenated to provide yet another member of this group of materials. The cycloaliphatic polymer backbones provide etch resistance, mechanical properties and stability to radiation. The lithographic function is provided by carefully tailored pendant groups, which include an acid functionality that is masked by protecting groups that undergo acid catalyzed thermolysis, as well as polar groups that influence the adhesion, wetability and dissolution properties of the polymer. The polymers are soluble in common organic solvents and have glass transition temperatures ranging from less than 60 degrees C to higher than 250 degrees C depending on their specific structure and mode of polymerisation. They are at least as transparent at 193 nm as the corresponding acrylics. Their dry etch resistance caries with the formulation, but the base polymers etch more slowly than novolac under conditions typically used to pattern polysilicon. Upon exposure and baking, the resists have demonstrated high sensitivities (9-25 mJ/cm(2)), and 0.16 mu m features have been resolved.