Accurate lithography analysis for yield prediction

Abstract

New DFM tools appearing on the market hold a promise of assessing parametric and functional yield loss due to lithography effects. The accuracy of underlying models can limit the veracity of such assessment. For example, many lithography steps used in the fab are extremely nonlinear and might exhibit significant differences from models used by the DFM tools. Furthermore, inputs used in calibrating a model can limit its accuracy, and most organizations are challenged to characterize the exact needs of a lithography model at a statistically relevant sampling size. After discussing potential sources of inaccuracy in modeling, the paper will describe a methodology for modeling and yield prediction based on such accurate modeling.