While critical lithographic feature size diminishes, resist profile can vary significantly as image varies. As a consequence, the final etch results are becoming more dependent on 3D resist profile rather than only a simple 2D resist image as an etch mask. Therefore, it has become necessary to build resist profile information into OPC models, which traditionally only contain 2D information in the x-y plane. At the same time, rigorous lithographic simulators are capable of modeling 3D resist profiles on a small chip area. In this work, one approach is investigated to account for 3D resist profile characteristics in full-chip OPC models with the assistance of rigorous simulation. With measurement data collected from experimental wafers, a rigorous resist model is first calibrated and verified. Then individual compact models are built to match the rigorous resist model profile at specified resist heights. The calibrated compact model for bottom resist line width corresponds to a conventional OPC model while resist profile is described by multiple models specified for certain resist heights, with each model being in the form of conventional compact models. In practice, the bottom model along with one or two models at critical heights are usually sufficient to detect sites where etch results become sensitive to resist profile. It has been found that the rigorous resist profile model can be well matched by the suggested compact models. For a quick application demonstration, hot spots of the etch results in the test case have been shown to be successfully captured by the calibrated compact models.
