Method and apparatus for wafer disposition based on systematic error modeling

摘要

A wafer-disposition method and apparatus are disclosed where the disposition is based on a model of systematic misalignment errors. The method comprises the steps of: modeling the misalignment errors between the mask and wafer as a mathematical model using measured misalignment data, generating a confidence limit of the probability of defect for the wafer, and determining whether the wafer satisfies a predetermined product quality level by comparing the confidence limit to the tolerance specification for the wafer. The misalignment model includes systematic errors and is represented by a polynomial based on the location of test points on the wafer. Preferably, several polynomials are formed and one that best predicts new misalignment data is selected. The confidence limit is created by combining the estimated probabilities of defect for all sliders in the wafer. Also, the product quality determination is based on a variable acceptance sampling procedure using the mathematical model.