Application of statistical analysis to determine the priority for improving LSI technology

LSI failures are classified into three categories: nonoperation failure, out-of-specification failure, and out-of-reliability failure. The first two are emphasized. The binomial-distribution model is applied for nonoperation failure, and the analysis-of-variance using the F -distribution is applied for the out-of-specification analysis where the distribution of each characteristic parameter is assumed to be the Gaussian distribution. The analysis is performed experimentally using a test chip. An independent evaluation of an elemental structure, which is defined as a critical structure, is the most important principle in test chip design. A new two-level database system is adopted for the statistical analysis based upon the analysis-of-variance. Methods to determine the priority for improving LSI technology are presented for both nonoperation and out-of-specification failures. This procedure effectively assists in improving LSI yield