Exposure of soft defects in integrated circuits using Taguchi methods

The work of Taguchi for determining the optimal settings of controllable factors through off-line experiments focuses on products with a single quality characteristic or response. However, most products have several quality characteristics or responses of interest. Taguchi's technique in itself optimizes a single response or performance characteristic yielding a set of process parameters. This particular setting may not give desired results for other characteristics of the product. In such cases, a need arises to obtain a single setting (optimal setting) of the process parameters, which can be used to produce the products with optimum or near optimum quality characteristics as a whole. Multi-characteristic response optimization may be the solution of the above problem. In the present paper a case study on frequency shift in a microprocessor is investigated utilizing a simplified multi-criterion methodology based on Taguchi's approach and utility concept, is discussed.