Patent ID: 7518717

Claim:
An exposure apparatus for performing an exposure of a Wafer to light via a mask while the mask and the wafer are scanned, said apparatus comprising: a projection optical system configured to project a pattern of the mask onto the wafer; a detection system configured to detect a position of a surface of the wafer in a direction of an optical axis of said projection optical system, with respect to each of a plurality of positions on the surface arranged along a direction of a scan of the wafer, while the scan is performed; a wafer stage configured to hold the wafer and to be moved, based on positions of the surface detected by said detection system, while the exposure is performed; and a controller configured to calculate a difference and to compare the difference with a threshold, the difference being a difference between two detected positions of a plurality of detected positions of the surface, the plurality of the detected positions of the surface being obtained by said detection system while the scan is performed, the two detected positions being obtained with respect to two successive positions of the plurality of positions on the surface, and each of the plurality of detected positions of the surface being obtained with respect to each of the optical axis direction and tilt directions, the difference being calculated and compared with the threshold with respect to each of the optical axis direction and the tilt directions to determine particle existence or particle non-existence on the wafer.