Patent ID: 7023523

Claim:
An exposure system, comprising: an illumination-optical system situated and configured to irradiate an illumination light on a reflective-type mask on which is formed a prescribed mask pattern, the illumination-optical system having a mask-side numerical aperture NA; a projection-optical system situated and configured to form an image of the illuminated mask pattern on a photosensitive substrate; the mask and the photosensitive substrate being respectively movable in a prescribed direction relative to the projection-optical system to project the illuminated mask pattern onto and expose the photosensitive substrate; and the illumination-optical system comprising a field stop, positioned in proximity to but separated by a distance i n from the mask and defining an illumination area on the mask, the field stop having an aperture portion having a width dimension w in a prescribed direction; wherein the following condition is satisfied: i n< 0.5 ×w /(2 ×NA+a n ), wherein a n is an angle of incidence (in radians) on the mask of a principal ray of the illumination light illuminating the mask.