Casual modeling of yield

Industry standard yield models make no provision for the heterogeneity of defect density or indication of how the uncertainty of defect density is propagated to uncertainty of die per wafer yield. In this paper we show how standard models can be extended by causal analysis to improve their generality. Causal diagrams are employed to specify yield models and make their assumptions transparent. Worked examples are provided as well as all the open-source code needed for the analyses.