Patent ID: 7277160

Claim:
A method for monitoring a focus quality during a lithogaphic exposure process comprising the steps of: providing a wafer having a plurality of fields on its surface, each field having a plurality of measurement patterns; displacing an optical system to each position of the plurality of measurement patterns of a wafer to generate a file for the wafer, the file comprising information about a size of the wafer, a position of the plurality of measurement patterns, an order of registering and capturing of the plurality of measurement patterns, and their alignment; selecting a plurality of selected measurement patterns and storing the positions of the plurality of selected measurement patterns in a master grid of the file for the wafer; for each position stored in the master grid of the file for the wafer, acquiring images of the plurality of selected measurement patterns, according to the order; and monitoring the focus quality by comparing an image obtained at the acquiring step to a golden image.