Patent ID: 7292311

Claim:
A scanning exposure apparatus for performing an exposure of a substrate to light via an original while the substrate and the original are scanned, said apparatus comprising: a projection optical system configured to project light from the original onto the substrate; a stage configured to hold the substrate and to move in a scanning direction perpendicular to an optical axis of said projection optical system; and a focus detector configured to detect a position of a surface region of the substrate in a direction of the optical axis, said apparatus being configured (i) to detect, using said focus detector, the position of the surface region with respect to each of a plurality of measurement points and with respect to each of a plurality of shot regions of the substrate, (ii) to average the detected positions over the plurality of shot regions with respect to each of the plurality of measurement points, (iii) to obtain a function which approximates the averaged positions respectively obtained with respect to the plurality of measurement points, wherein the function includes a polynomial with respect to a position within a plane perpendicular to the optical axis, (iv) to calculate a difference between each of the averaged positions and a value of the obtained function with respect to each of the plurality of measurement points, (v) to offset a position detected by said focus detector with respect to each of the plurality of measurement points with a corresponding one of the calculated differences, (vi) to control a position of said stage based on each of the offset positions during the exposure, (vii) to obtain the function with respect to a subset of substrates within a lot of substrates, the subset including the first substrate within the lot, and (viii) to change at least one of a degree and number of terms of the polynomial.