Wafer-Level Characteristic Variation Modeling Considering Systematic Discontinuous Effects

Statistical wafer-level variation modeling is an attractive method for reducing the measurement cost in large-scale integrated circuit (LSI) testing while maintaining the test quality. In this method, the performance of unmeasured LSI circuits manufactured on a wafer is statistically predicted from a few measured LSI circuits. Conventional statistical methods model spatially smooth variations in wafer. However, actual wafers may have discontinuous variations that are systematically caused by the manufacturing environments, such as shot dependence. In this study, we propose a modeling method that considers discontinuous variations in wafer charac-teristics by applying the knowledge of manufacturing engineers to a model estimated using Gaussian process regression. In the proposed method, the process variation is decomposed into the systematic discontinuous and global components to improve the estimation accuracy. An evaluation performed using an industrial production test dataset shows that the proposed method reduces the estimation error for an entire wafer by over 33% compared to conventional methods.