Efficient extra material critical area algorithms

Two algorithms that calculate the critical areas of integrated circuit mask layout for extra material defects are presented. The first algorithm generates a set of edges that define the critical area of the layout for a given defect size. The second algorithm generates the set of fault critical area edges. These identify all possible extra material circuit faults that can occur from a defect of a given size. The edges are used to generate fault critical areas which are classified by the list of circuit nodes that are shorted by a defect of a given size falling within that area. These algorithms can be used as a framework on which other critical area algorithms can be generated, notably missing material and pinhole critical generation. The algorithms presented in this paper have the advantage that they are not restricted to Manhattan layout and that they are computationally efficient