Etcher overlay control by applying an electrical or magnetic field with gradients

摘要

Etcher control may offer additional overlay correction potential (on top of the scanner control capabilities) for controlling After Etch overlay (AEI). After lot exposure typically the After Development (ADD overlay is measured. When a significant overlay in resist is measured currently the only way to correct for it is by stripping, coating and exposing the wafer again. This is a costly procedure (e.g. because valuable scanner time is required, but also extra process steps).