Model based Sub-Resolution Assist Features Using an Inverse Lithography Method

The conventional segment-based OPC approach has been applied successfully for many CMOS generations and is currently favored. However, Inverse lithography technology (ILT) is a promising candidate for next-generation optical proximity correction (OPC). Still, there are issues that need to be thoroughly addressed and further optimized. In this work, we propose a model-based pre-OPC flow where the sizing of drawn patterns and placement of surrounding sub-resolution assist features (SRAF) are simultaneously generated in a single iteration using an ILT method. The complex patterns can then be simplified for a conventional OPC solution.