Efficient Boolean Operations on IC Masks

Circuit extraction and design rule checking programs make extensive use of Boolean operations which accept IC mask data as operands. A wide variety of computer algorithms have been written that implement Boolean operations on sets of geometric entities. These algorithms vary in their efficiency and can be characterized by how they represent, sort, and compare IC artwork files. A bit-map representation of IC layout data precisely localizes mask information and eliminates the need for sorting the layout data prior to or during the performance of Boolean operations. The bit patterns of the mask operands may be compared using the CPU's own Boolean operators. A compacted bit-map format that can represent IC layouts concisely, therefore, provides an excellent data base for a very efficient algorithm to perform geometric Boolean operations.