Patent ID: 7196801
Filing Date: 2007-03-27
Classification: G01B

Abstract:
1. A method for measuring surface characteristics of a substrate having a repeating pattern of integrated circuits, the repeating pattern having a repeat dimension along a first axis, the method including the steps of: defining an inspection grid of points on the substrate, the inspection grid of points having a spacing along the first axis, directing an incident beam at the inspection grid of points on the substrate where the spacing of the points along the first axis is a submultiple of the repeat dimension of the repeating pattern along the first axis, reflecting the incident beam off the substrate to produce a reflected beam, receiving the reflected beam with a position sensitive detector, determining an actual landing location of the reflected beam on the position sensitive detector, measuring a displacement between the actual landing location of the reflected beam from an expected landing location of the reflected beam on the position sensitive detector, compiling a database of displacement measurements, examining at least two displacement measurements in the database, correcting at least one displacement measurement for effects of a pattern induced anomaly in the displacement measurements and producing an adjusted database, and deriving the surface characteristics of the substrate from the adjusted database.