Ceramic ring undersize detection device

摘要

The present invention concerns a testing object for use in the testing of a wafer clamp. Wafer clamps are used to hold wafers in position on etchers. If the wafer clamp is worn, the process yield drops due to the heating of the wafer and subsequent photoresist melting. The testing object passes wafer clamps having a sufficient wafer overlap distance, but fails wafer clamps without a sufficient wafer overlap distance.