Improved testpatterns and coverage for complex SrAF to optimize 5nm and below OPC and mask patterning

摘要

Below the 28nm node the difficulty of using subresolution assist features (SrAFs) in OPC/RET schemes increases substantially with each new device node. This increase in difficulty is due to the need for tighter process window control for smaller target patterns, the increased risk of SrAF printing , and also the increased difficulty of SrAF mask manufacture and inspection. Therefore, there is a substantially increased risk of SrAFs which violate one or more manufacturability limits. In this paper, we present results of our work to evaluate methods to pre-characterize designs which are likely to become problematic for SrAF placement. We do this by evaluating different machine learning methods, inputs and functions.