Patent ID: 7502098

Claim:
An exposure apparatus comprising: a projection optical system configured to project light from a reticle onto a substrate; and a detector configured to detect a position of a surface of the substrate in a direction of the optical axis of the projection optical system, wherein the apparatus is configured, while the reticle and the substrate are moved in a scanning direction crossing the optical axis, to detect the position of the surface in a shot on the substrate with the detector, to subtract an offset value determined in advance from the detected position, to move the substrate in the direction of the optical axis based on the subtraction value, and to expose the substrate to light via the reticle and the projection optical system, wherein, with respect to each of a plurality of shots on the substrate, a line or surface is calculated which approximates a plurality of positions of the surface detected by the detector with respect to a plurality of places, and a difference between the position of the surface detected by the detector and the position of the line or surface in the direction of the optical axis is calculated with respect to each of the plurality of places, and wherein with respect to each of the plurality of places, the differences are averaged over the plurality of shots to determine the offset value.