Disclosed is an exposure apparatus for illuminating a reflection type mask
with light from a light source and for exposing a substrate with a pattern of the
illuminated reflection type mask, wherein the apparatus includes a projection optical
system for projecting the pattern of the reflection type mask onto the substrate,
the projection optical system having a stop, wherein the stop has a first opening
for defining a numerical aperture of the projection optical system, and a second
opening through which light from the reflection type mask passes. This structure
effective avoids unwanted physical interference among optical components of an
illumination system or the projection optical system even when the size of the
whole exposure apparatus is made compact to some degree.
