Projection optical system and an exposure apparatus with the projection optical system

Abstract

A projection optical system, which forms a reduced image of a first surface onto a second surface, has excellent optical performance without substantially being affected by birefringence despite the use of optical material having intrinsic birefringence. This is done by suitably arranging certain crystal axes of radiation transmissive members that make up the projection optical system relative to the optical axis of the projection optical system, and by suitably arranging the certain crystal axes of the radiation transmissive members relative to the crystal axes of other radiation transmissive members in the projection optical system.

1 . A projection optical system capable of forming a reduced image of a first surface at a second surface, and that includes a plurality of lenses and at least one concave reflective mirror, wherein the projection optical system: 
 when used in an exposure apparatus to scan expose the first surface at the second surface while moving the first surface and the second surface along a scanning direction, forms a slit-shaped or arc-shaped exposure area at the second surface when not scanning; and satisfies the condition      0.5<( Dw·Nw )/ Ew< 1.4  (1)    where Dw is a working distance of the second surface side, Nw is a numerical aperture of the second surface side, and Ew is a length in a direction orthogonal to the scanning direction of the slit-shaped or arc-shaped exposure area.    
   
   
       2 . A projection optical system according to  claim 1 , wherein the slit-shaped or arc-shaped exposure area does not intersect an optical axis of the projection optical system, and the projection optical system further comprises: 
 a) a refractive type first optical imaging system to form a first intermediate image of the first surface;    b) a second optical imaging system, having at least one negative lens and a concave reflective mirror, to form the first intermediate image into a second intermediate image of nearly the same magnification near the first intermediate image forming position based on the light beam from the first intermediate image;    c) a refractive type third optical imaging system to form a reduced image of the second intermediate image onto the second surface based on the light beam from the second intermediate image;    d) a first optical path folding mirror arranged in the optical path between the first optical imaging system and the second optical imaging system; and    e) a second optical path folding mirror arranged in the optical path between the second optical imaging system and the third optical imaging system.    
   
   
       3 . A projection optical system according to  claim 2 , wherein all lenses comprising the first optical imaging system and the third optical imaging system are arranged along a single straight line along the optical axis.  
   
   
       4 . An exposure apparatus comprising: 
 an illumination system to illuminate a mask serving as the first surface; and    a projection optical system according to  claim 1  to form an image of a pattern on the mask onto a photosensitive substrate serving as the second surface.    
   
   
       5 . A projection optical system including a plurality of lenses, a concave reflective mirror and a negative lens arranged in proximity to the concave reflective mirror, and capable of forming a reduced image of a first surface at a second surface, wherein the projection optical system: 
 a) when used in an exposure apparatus to scan expose the first surface at the second surface while moving the first surface and the second surface along a scanning direction, forms a slit-shaped or arc-shaped exposure area at the second surface when not scanning; and    b) a numerical aperture of the second surface side is 0.82 or more.    
   
   
       6 . A projection optical system according to  claim 5 , wherein: 
 a) the concave reflective mirror and the negative lens are arranged along an optical axis in a direction substantially different from a direction of gravity, and    b) the following conditional expression is satisfied:      1.0 <S/|R|< 1.8  (2)    wherein S is a clear aperture (diameter) of the concave reflective mirror and R is a radius of curvature of the concave reflective mirror.    
   
   
       7 . An exposure apparatus comprising: 
 an illumination system to illuminate a mask serving as the first surface; and    a projection optical system according to  claim 5  to form an image of a pattern on the mask onto a photosensitive substrate serving as the second surface.