Level-specific strategy of KrF microlithography for 130 nm DRAMs

This paper reports technologies that enable KrF microlithography to be extended to 130 nm generation devices. Firstly, focus and dose budget analyses are carried out carefully to estimate their total deviations. Secondly, level specific cell-array patterns and exposure conditions are optimized for obtaining more process windows than the deviations by experiment and simulation. Optical proximity effect (OPE) and process proximity effect (PPE) for each level are investigated for core and peripheral circuit patterns. The key technologies for KrF microlithography, i.e. resolution enhancement technologies (RET) and process proximity correction (PPC), are discussed with a view to realizing 130 nm DRAMs.