Robust PPC and DFM methodology for exposure tool variations

Robust optical proximity correction (OPC) and design for manufacturability (DFM) methodology for optical variation among exposure tools is proposed. It is demonstrated that application of the methodology improves standard deviation of CD difference for target CD by 33% compared with the case of using the conventional methodology. Under the low-k1 lithography condition, hot spots induced by optical variation among exposure tools delay ramp-up of production of high-volume products. To realize robust pattern formation for all exposure tools, the following new methodologies are introduced : i) OPC modeling methodology using actual optics of primary tool, ii) OPC processing methodology using averaged or designed optics, iii) at the design stage, hot spot detection within the optical variation space centered on average or designed optics and hot spot fixing by layout modification or OPC optimization, iv) at the manufacturing stage, hot spot detection using actual optics and hot spot fixing by optical adjustment of troubled tool.