Abstract

The present invention discloses apparatus and method for electronically determining and compensating mechanical fixture induced errors from desired object related information in a measurement system such that data acquisition is obtained with a precision very much better than the manufacturing tolerances of the mechanical fixture. In the preferred embodiment, bow and warp profiles of a semiconductor wafer are obtained with an X, θ, and Z moveable wafer-receiving chuck that have an accuracy very much better than the mechanical tolerances of the X, θ, and Z moveable chuck. The system provides for measurement of objectrelated information in plural orientations. Signal processing is disclosed for separating out of the object related information X and θ fixture induced error contributions to the data arising from mechanical tolerance of the fixture. Signal processing is disclosed for compensating bow and warp profiles of semiconductor wafers in accordance with the X and θ contributions fixture induced error are disclosed in order to provide a measurement accuracy not limited by the mechanical tolerances of the X, θ, and Z moveable wafer after receiving chuck.