Source mask optimization methodology (SMO) and application to real full chip optical proximity correction

摘要

Due to the continuous shrinking in half pitch and critical dimension (CD) in wafer processing, maintaining a reasonableprocess window such as depth of focus (DOF) & exposure latitude (EL) becomes very challenging. With the sourcemask optimization (SMO) methodology, the lithography process window can be improved and a smaller mask errorenhancement factor (MEEF) can be achieved.In this paper, the Tachyon SMO work flow and methodology was evaluated. The optimum source was achieved throughevaluation of the critical designs with Tachyon SMO software and the simulated performance was then verified onanother test case. Criteria such as DOF, EL & MEEF were used to determine the optimum source achieved from theevaluation. Furthermore, the process variation band (PV-Band) and the number of hot spot (design weak points) werecompared between the POR and the optimum source. The simulation result shows the DOF, MEEF & worst PV-Bandwere improved by 13%, 17% & 12%, respectively with the optimum SMO source.In order to verify the improvement from the optimum SMO at the silicon level, a new OPC model was recalibrated withwafer CD from the optimized source. The OPC recipe was also optimized and a reticle was retrofitted with the new OPC.By comparing the process window, hotspots and defects between the original vs. new reticle, the benefit of the optimizedsource was verified on silicon.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.