Patent ID: 6920249

Claim:
A method for determining the position of an edge to be measured of a pattern element on a substrate, in which a one-dimensional measured intensity profile is ascertained from a camera image of the edge and the position p of the edge relative to a reference point is determined therefrom, comprising the steps: a) ascertaining and storing a complete, nonlinear model intensity profile, which identifies the edge to be measured, of a model edge; b) defining with subpixel accuracy a desired model edge position x k in the model intensity profile; c) acquiring a camera image, made up of pixel rows and pixel columns, of the edge to be measured; d) placing a rectangular measurement window onto the camera image transversely over the edge; e) determining from the image signals of the pixels of the measurement window a one-dimensional measured intensity profile of the edge; f) identifying the model intensity profile in the measured intensity profile with an indication of its location x m relative to a reference point; and g) determining with subpixel accuracy the position p, referred to said reference point, of the edge to be measured, as p=x m + k .