Patent ID: 8345220

Claim:
A method for measuring a coma aberration amount of a projection optical system that projects an image of a pattern formed on an original plate onto a substrate, the method comprising: obtaining a first position of an image of a mark on the side of an object plane in a plane perpendicular to an optical axis of the projection optical system under a first illumination condition, by illuminating the mark on the side of the object plan using the first illumination condition so as to project the image of the mark on the side of the object plane onto a mark on the side of an image plane using the projection optical system, and by changing a position of the mark on the side of the image plane in the plane perpendicular to the optical axis of the projection optical system so as to detect light passing through the mark on the side of the image plane at a plurality of positions in the plane perpendicular to the optical axis of the projection optical system; obtaining a second position of an image of the mark on the side of the object plane in a defocus plane being perpendicular to the optical axis and being defocused in a direction of the optical axis under a second illumination condition, by illuminating the mark on the side of the object plane using the second illumination condition so as to project the image of the mark on the side of the object plan onto the mark on the side of the image plane using the projection optical system, and by changing a position of the mark on the side of the image plane in the defocus plane perpendicular to the optical axis of the projection optical system so as to detect light passing through the mark on the side of the image plane at a plurality of positions in the defocus plane; and calculating the coma aberration amount of the projection optical system based on a difference between the first position and the second position, wherein the first illumination condition is a condition under which the position of the image of the mark on the side of the object plane in the plane perpendicular to the optical axis with respect to the coma aberration amount does not change, and wherein the second illumination condition is a condition under which the position of the image of the mark on the side of the object plane in the defocus plane with respect to the coma aberration amount changes.