Method and apparatus for wafer disposition based on systematic error modeling

A computer program product for use with a computer-based photo-lithography system for wafer disposition, the system having a mask, a wafer having a plurality of sliders, and means for obtaining misalignment data between the mask and wafer for a plurality of test points on the wafer, the computer program product comprising:

• a computer readable medium;
• means, provided on the computer-readable medium, for directing the system to model misalignment errors between the mask and wafer as a mathematical model using the misalignment data on the test points, said model being based on dependent matrices representing a constant model, a linear model, and a quadratic model of systematic errors;
• means, provided on the computer-readable medium, for directing the system to estimate a probability of defect for each slider based on the model;
• means, provided on the computer-readable medium, for directing the system to combine the probabilities of defect for all the sliders to generate a confidence limit of the probability of defect for the wafer;
• means, provided on the computer-readable medium, for directing the system to determine whether the wafer satisfies a predetermined product quality level by comparing the confidence limit to a predetermined tolerance specification for the wafer;
• and
• means, provided on the computer-readable medium, for directing the system to accept or reject the wafer based on said determination.

A wafer disposition apparatus for use with a photo-lithography system, the system having a wafer including a plurality of sliders, a mask for transferring device features to the wafer, and means for obtaining misalignment data between the mask and wafer for a plurality of test points on the wafer, the apparatus comprising:

• means for modeling misalignment errors between the mask and wafer as a mathematical model using the misalignment data on the test points, said model being based on dependent matrices representing a constant model, a linear model, and a quadratic model of systematic errors;
• means for estimating a probability of defect for each slider based on the model;
• means for combining the probabilities of defect for all the sliders to generate a confidence limit of the probability of defect for the wafer;
• means for determining whether the wafer satisfies a predetermined product quality level by comparing the confidence limit to a predetermined tolerance specification for the wafer;
• and
• means for accepting or rejecting the wafer based on said determination.