This paper describes the use of automated discovery from databases for diagnosing the causes of rotsprocessing during semiconductor manufacturing. The databaseonlains the historyof the semieonduc4or wafers as theTI undergo various processing steps. A generate-and-test approach is taken for using such a database for automated diagnosis. Based on prior maaual use of such databases, classes of queries to the database useful for fault isolation are identified. Patterns in the responses to these queries that are useful for fault isolation are also identified. Automated diagnosis is accomplished bll automating query generation and the detection of potentially useful paflergs. A prototype system was implemented and tested on a database from a wafer grinding and polishing facility. In addition to identifying previously known faults, the system also identified previously unknoum faults.