Yield optimization of integrated circuits

A design approach is presented that optimizes the component areas of integrated circuits so as to maximize the yield. The performance index to be optimized is defined as the chip yield divided by the chip area, which corresponds to the number of good chips in a wafer. The area of each component is determined to maximize this performance index by a nonlinear programming technique. The design of integrated circuits with respect to the yield may be mostly narrowed down to the determination of component areas, since the process parameters cannot be adjusted individually for each circuit component. This design approach is described in more detail for the kinds of components whose surface areas cannot be uniquely determined by their nominal parameter values. As a demonstration, the width of a diffused resistor in bipolar integrated circuits was optimized for some example circuits. Some useful results have been obtained for the design of circuit patterns.