Asymmetries in wafer map defects are usually treated as random production hardware defects. For example, asymmetric wafer defects can be caused by particles inadvertently deposited on a wafer during ...

Full-blown process excursions that affect every wafer are comparatively easy for fabs to detect and fix. However, “onesie-twosie,” lower-volume excursions can go unresolved for months or even years.