Modeling defect spatial distribution

The center-satellite model for describing the distribution of defects on wafers is discussed. This model assigns each defect to a cluster. The distribution of cluster centers on a wafer is one basic component of the model. The other basic component is the distribution of defects (satellites) about the cluster centers. Physical justification for the model is provided. Current yield models are quite accurate for VLSI designs without redundancy. A more flexible model is needed to evaluate the redundancy techniques that will be an integral part of WSI. An example is provided to demonstrate the type of analysis necessary to analyze fault-tolerant designs using the model. Empirical research needed to obtain parameters for the model is commented on, as is the need to reevaluate prior empirical research in which assumptions were made that are relaxed by the center-satellite model