Patent ID: 7307715

Claim:
A method of processing a workpiece, the method comprising: providing a workpiece that includes a structure that has a structure size, the workpiece comprising a mask or a substrate; measuring the structure size of the structure to determine an auxiliary measured value; determining a calibration measured value on the basis of a calibration structure, the calibration structure including at least two structure elements at a distance from one another, the calibration measured value based on at least a measured value sum of the width of one of the two structure elements and a distance between the two structure elements; determining a calibration factor based on the calibration measured value and a predetermined calibration preset value that relates to the calibration structure; correcting the auxiliary measured value using the calibration factor thereby determining the structure size measured value; and evaluating the workpiece based upon the structure sized measured value; wherein a calibration factor is determined for each of at least two different measurement directions; and wherein the auxiliary measured value is corrected taking account of the determined calibration factors and taking into account the amount by which the structure to be measured extends along the different measurement directions.