Interferometer system and method of manufacturing projection optical system using same

Abstract

A method of manufacturing a projection optical system ( 37 ) for projecting a pattern from a reticle to a photosensitive substrate, comprising a surface-shape-measuring step wherein the shape of an optical test surface ( 38 ) of an optical element ( 36 ) which is a component in the projection optical system is measured by causing interference between light from the optical surface ( 38 ) and light from an aspheric reference surface ( 70 ) while the optical test surface ( 38 ) and said reference surface ( 70 ) are held in integral fashion in close mutual proximity. A wavefront-aberration-measuring step is included, wherein the optical element is assembled in the projection optical system and the wavefront aberration of the projection optical system is measured. A surface correction calculation step is also included wherein the amount by which the shape of the optical test surface should be corrected is calculated based on wavefront aberration data obtained at the wavefront-aberration-measuring step and surface shape data obtained from the surface-shape-measuring step. The method also includes a surface shape correction step wherein the shape of the optical test surface is corrected based on calculation performed at the surface correction calculation step. Surface shape measuring interferometer systems and wavefront-aberration-measuring interferometer systems ( 22 J- 22 Q) used in performing the manufacturing method are also disclosed.

What is claimed is:  
     
         1 . An apparatus for measuring wavefront aberration of an optical system having an image plane and an object plane, comprising: 
 a laser plasma X-ray light source;    a first pinhole member provided with a first pinhole group comprising a plurality of first pinholes that generate a plurality of first spherical waves based on the light;    a second pinhole member provided with a second pinhole group comprising a plurality of second pinholes arranged at an imaging position where the first pinhole member is imaged by the optical system;    a diffraction grating arranged in an optical path between the first and second pinhole members, and arranged so that zeroeth order diffracted light passing through the first pinhole group reaches the second pinhole group;    diffracted light selection means for selectively transmitting diffracted light of a predetermined order from among diffracted light of first order and higher order from the diffraction grating; and    a detector that detects interference fringes obtained by interference of a second spherical wave generated by the zeroeth order diffracted light passing through the second pinhole group, and the diffracted light of the predetermined order passing through the diffracted light selection means.    
     
     
         2 . An apparatus according to  claim 1 , wherein: 
 the first pinhole member includes a plurality of first slit groups;    the second pinhole member includes a plurality of the second pinhole groups arranged corresponding to the imaging position where the plurality of first pinhole groups are imaged by the optical system; and    the diffracted light selection means is a plate having a plurality of apertures for selectively transmitting the plurality of diffracted light of the predetermined order generated by passing through the diffraction grating a plurality of light beams proceeding to a plurality of imaging positions.    
     
     
         3 . An apparatus according to  claim 2 , further comprising: 
 first selective illumination means for selectively illuminating a first portion of the plurality of first pinholes of the first pinhole member; and    selective light receiving means for selectively receiving a second ideal spherical wavefront from a second portion of the plurality of second pinholes corresponding to the first portion, and diffracted light of the predetermined order that passes through the second portion.    
     
     
         4 . An apparatus according to  claim 2 , further comprising second selective illumination means for selectively illuminating a portion of the second pinhole groups from among the plurality of second pinhole groups.  
     
     
         5 . An apparatus for measuring wavefront aberration in an optical system having an image plane and an object plane, comprising: 
 a laser plasma X-ray light source that generates X-ray light;    a first slit member provided with a first slit group comprising a plurality of first slits that generate a plurality of first one-dimensional spherical waves based on the X-ray light from the light source;    a second slit member provided with a second slit group comprising a plurality of second slits arranged at an imaging position where the first slit member is imaged by the optical system;    a diffraction grating arranged in an optical path between the first and second slit members, and arranged so that a zeroeth order diffracted light of the X-ray light passing through the first slit group reaches the second slit group;    diffracted light selection means for selectively transmitting diffracted X-ray light of non-zero order; and    a detector that detects interference fringes arising from interference between a second one-dimensional spherical wave generated when the zeroeth order X-ray light passes through the second slit group and the non-zeroeth order diffracted X-ray light passing through the diffracted light selection means.    
     
     
         6 . An apparatus according to  claim 5 , wherein: 
 the first slit member includes a plurality of the first slit groups;    the second slit member includes a plurality of second slit groups arranged corresponding to a plurality of imaging positions where the plurality of first slit groups are imaged by the optical system; and    the diffracted light selection means has a plurality of apertures for selectively transmitting a plurality of diffracted X-ray light generated by passing through the diffraction grating a plurality of light beams proceeding to the plurality of imaging positions.    
     
     
         7 . An apparatus according to  claim 6 , further comprising: 
 first selective illumination means for selectively illuminating a first portion of the plurality of first slit groups; and    selective light receiving means for selectively receiving a second one-dimensional spherical wavefront from a second-portion of the plurality of second slit groups corresponding to the first portion, and diffracted light of the predetermined order that passes through the second portion.    
     
     
         8 . An apparatus according to  claim 7 , further comprising second selective illumination means for selectively illuminating a portion of the second slit groups from among the plurality of second slit groups.  
     
     
         9 . An apparatus for measuring wavefront aberration in an optical system, comprising: 
 a laser plasma X-ray light source for generating X-ray light;    a slit member provided with a first slit group comprising a plurality of slits that generate a plurality of one-dimensional spherical waves based on the light from the light source;    a diffraction grating arranged in an optical path between the slit member and an imaging position where the slit member is imaged by the optical system, and that generates diffracted light from light passing therethrough;    diffracted light selection means for selectively transmitting diffracted light of a predetermined order and diffracted light of an order different than the predetermined order; and    a detector arranged so as to detect interference fringes from interference between the diffracted light of the predetermined order and the diffracted light of an order different than the predetermined order to allow calculation of the wavefront aberration from the interference fringes.    
     
     
         10 . An apparatus for measuring wavefront aberration in an optical system having an incident-side numerical aperture NA, an object plane and an image plane, the apparatus comprising: 
 an X-ray light source for generating X-ray light having a wavelength λ;    a first pinhole plate having an aperture smaller than 0.6 λ/NA arranged at the object plane;    a Hartmann plate arranged between the first pinhole plate and the image plane, the Hartmann plate having a plurality of apertures; and    a detector arranged adjacent the image plane so as to detect a position of a plurality of ray groups passing through the plurality of apertures of the Hartmann plate;    wherein the wavefront aberration is calculated based on the position of the plurality of ray groups detected by the detector.    
     
     
         11 . An apparatus according to  claim 10 , wherein the Hartmann plate is arranged between the optical system and the image plane.  
     
     
         12 . An apparatus according to  claim 11 , further comprising: 
 first selective illumination means for selectively illuminating a portion of slit groups from among a plurality of slit groups;    detector position changing means that changes a detection position of the detector so as to detect the ray groups based on light passing through the portion of the slit groups, wherein a slit member is provided with a plurality of the slit groups.