On the definition of critical areas for IC photolithographic spot defects

The model presented is a generalization of existing theory. The sensitive areas are a function of the geometrical patterns in the layers, their electrical significance, their relationship to patterns in other layers, and the defect size. Identifying composite sensitive areas makes it possible to predict the probability of failure of special structures such as transistors and capacitors, which in turn eases the problem of predicting accurately and realistically the circuit design yield with respect to photolithographic defects. Two general expressions are developed to find the critical areas for extra and missing materials. The approach followed makes use of `safe extend' factors which must be set independently for each structure with an electrical significance in the layout