AN ANALYSIS OF A SEMICONDUCTOR EXPERIMENT USING YIELD AND SPATIAL INFORMATION

Semiconductor yield data is binary by nature since an integrated circu it (IC), or die, can only pass or fail a particular test. Still, many people rely on simple linear regression to analyse this type of data, which can produce incorrect results, e.g. negative yield predictions. We discuss the use of logistic regression for the analysis of yield da ta, and show that even this approach has to be modified to take into a ccount the phenomenon of overdispersion. We present several approaches to accommodate overdispersion. We also discuss a statistic for measur ing the spatial dependence of ICs within a wafer, the spatial log-odds ratio, which provides additional information to complement a yield an alysis. These ideas are demonstrated using an example from our manufac turing area. (C) 1997 by John Wiley & Sons, Ltd.