Patent US 5,483,636

A system and method for isolating one or more causes of wafer misprocessing. A list of interesting queries (10) is generated. During wafer processing (15), processing parameters are measured (20) and a wafer tracking database (25) is created. The list of queries (10) may be filtered (30) before the queries are tested for interestingness. Interestingness is determined by outlier calculation (35) and trend analysis (40) on data stored in the wafer tracking database (25). Queries found to be interesting are displayed (50).