Optical proximity correction of alternating phase shift masks for 0.18 mu m KrF lithography

Optical proximity correction (OPC) was applied to alternating phase shift masks to improve printed resist pattern fidelity. Mask patterns were modified with jog type corrections. DRAM cell patterns were exposed by using a 0.55 NA, 0.36/0.55 sigma, KrF excimer laser stepper onto 0.5 mu m thick chemically amplified negative resist. With 0.55 sigma, OPC was effective and printed resist pattern was very close to designed one. However, with 0.36 sigma, large pattern deformation was observed due to coma aberration.