Exposure method, exposure apparatus, method for adjusting the exposure apparatus, and device manufacturing method

Abstract

Attention is paid to the phenomenon that a static image distortion characteristic is averaged in the width of a projection area in a scanning direction and becomes a dynamic image distortion characteristic, when a mask pattern is scan-exposed onto a photosensitized substrate by a projection exposure apparatus. At least a random component included in the dynamic image distortion characteristic is corrected by arranging an image correction plate obtained by locally polishing the surface of a transparent parallel plate. Correction plates which minimize other aberrations beforehand are manufactured and installed within a projection optical path, considering that also the other aberrations are averaged and become dynamic aberration characteristics at the time of scan-exposure.

What is claimed is:  
     
         1 . An exposure method transferring a pattern of a mask onto a substrate, comprising: 
 arranging the mask on an object plane side of a projection optical system having a predetermined image formation characteristic;    arranging a photosensitized substrate on an image plane side of the projection optical system;    restricting a partial image of the mask, which is projected onto the image plane side, to within a projection area having a predetermined width in a one-dimensional scanning direction; and    performing a scanning exposure of the sensitized substrate by moving the mask and the substrate in a state where at least one correction optical element, which is optically processed so that an average aberration characteristic obtained by averaging projection aberrations at a plurality of image points existing along the scanning direction in the projection area become a predetermined state respectively at a plurality of positions in a non-scanning direction intersecting the scanning direction of the projection area, is arranged in an optical path for imaging by the projection optical system.    
     
     
         2 . The method according to  claim 1 , wherein the correction optical element is made of a transparent optical glass material arranged at least one of the object plane side and the image plane side, and a surface portion corresponding to the projection area of the transparent optical glass material is optically processed to be a locally different plane shape so that the averaged projection aberrations respectively at the plurality of positions in the non-scanning direction become almost identical.  
     
     
         3 . The method according to  claim 1 , wherein the optical correction element includes a correction plate for correcting a dynamic projection aberration characteristic occurring at the time of said scannin exposure.  
     
     
         4 . The method according to  claim 1 , wherein the optical correction element includes an image correction plate for correcting a distortion characteristic, which is arranged on the object plane side of the projection optical system.  
     
     
         5 . The method according to  claim 1 , wherein the optical correction element includes an astigmatism correction plate for correcting an astigmatism aberration characteristic, which is arranged on the image plane side of the projection optical system.  
     
     
         6 . The method according to  claim 1 , wherein the optical correction element includes a coma correction plate which is arranged on the image plane side of the projection optical system, and corrects a coma aberration characteristic.  
     
     
         7 . The method according to  claim 1 , wherein the optical correction element includes an image plane curvature correction plate which is arranged on the image plane side of the projection optical system, and corrects an image plane curvature characteristic.  
     
     
         8 . The method according to  claim 1 , wherein the scanning exposure of the substrate is performed while projecting an image of the pattern of the mask onto the substrate through the projection optical system in a state where an illumination aberration correction member for correcting an optical aberration of an illumination light irradiated on the mask is arranged in an optical path of the illumination light.  
     
     
         9 . The method according to  claim 8 , wherein the illumination aberration correction member corrects an aberration caused by at least one of an entire telecentric error of an illumination light irradiated on the mask or a test reticle, a local telecentric error of the illumination light, and an error of an illumination numerical aperture varying according to a position within a field of the projection optical system.  
     
     
         10 . The method according to  claim 1 , wherein the projection aberration is measured by using an image detector which is attached to part of a substrate stage that supports the sensitized substrate and can move, and comprises an small aperture receiving a projection image of a measurement mark of a test reticle arranged on the object plane side of the projection optical system.  
     
     
         11 . An exposure method in which a substrate is exposed by projecting an image of a pattern of a mask onto the substrate through a projection optical system, comprising: 
 arranging the mask and the substrate; and    projecting the image of the pattern of the mask through the projection optical system in a state where a coma correction plate respectively correcting random coma characteristics of respective images at a plurality of positions within a projection area of the projection optical system is arranged between the mask and the substrate.    
     
     
         12 . The method according to  claim 11 , wherein a surface portion of the coma correction plate, which corresponds to the projection area, is optically processed to be a predetermined shape in a local manner, so that the random coma characteristics of the respective images at the plurality of positions within the projection area are respectively corrected.  
     
     
         13 . The method according to  claim 12 , wherein: 
 a coma characteristic of a projection image at each of a plurality of positions within the projection area is measured; and    the coma correction plate is optically processed based on a measurement result.    
     
     
         14 . The method according to  claim 11 , wherein: 
 a scanning exposure of the substrate is performed by synchronously moving the mask and the substrate relative to the projection optical system; and    the coma correction plate corrects a dynamic coma characteristic occurring during the scanning exposure.    
     
     
         15 . An exposure method in which a substrate is exposed by projecting an image of a pattern of a mask onto the substrate through a projection optical system, comprising: 
 arranging the mask and the substrate; and    projecting the image of the pattern of the mask through the projection optical system in a state where an astigmatism correction plate respectively correcting random astigmatism characteristics of respective images at a plurality of positions within a projection area of the projection optical system is arranged between the mask and the substrate.    
     
     
         16 . The method according to  claim 15 , wherein a surface portion of the astigmatism correction plate, which corresponds to the projection area, is optically processed to be a predetermined shape in a local manner, so that the random astigmatism characteristics of the respective images at the plurality of positions within the projection area are respectively corrected.  
     
     
         17 . The method according to  claim 16 , wherein: 
 an astigmatism characteristic of a projection image at each of a plurality of positions within the projection area is measured; and    the astigmatism correction plate is optically processed based on a measurement result.    
     
     
         18 . The method according to  claim 15 , wherein: 
 a scanning exposure of the substrate is performed by synchronously moving the mask and the substrate relative to the projection optical system; and    the astigmatism correction plate corrects a dynamic astigmatism characteristic occurring during the scaning exposure.    
     
     
         19 . An exposure apparatus exposing a substrate by projecting an image of a pattern of a mask onto, the substrate, comprising: 
 a projection optical system, which is arranged between the mask and the substrate, projecting the image of the pattern of the mask onto the substrate; and    an astigmatism correction plate correcting a non-linear astigmatism characteristic at each image at a plurality of positions within a projection area of said projection optical system.    
     
     
         20 . The exposure apparatus according to  claim 19 , further comprising 
 a measurement device, which is arranged on an image plane side of said projection optical system, measuring an astigmatism characteristic at each of a plurality of positions within the projection area.    
     
     
         21 . The exposure apparatus according to  claim 19 , further comprising 
 an image plane curvature correction member, which is arranged between the mask and the substrate, correcting non-linear image plane curvature occurring at each of a plurality of positions within the projection area of said projection optical system.    
     
     
         22 . The exposure apparatus according to  claim 19 , further comprising 
 a distortion correction member, which is arranged between the mask and the substrate, respectively correcting non-linear distortions of respective images at a plurality of positions within the projection area of said projection optical system.    
     
     
         23 . An exposure apparatus exposing a substrate by projecting an image of a pattern of a mask onto the substrate, comprising: 
 a projection optical system, which is arranged between the mask and the substrate, projecting the image of the pattern of the mask onto the substrate; and    a coma correction plate, which is arranged between the mask and the substrate, correcting a non-linear coma characteristic of each image at a plurality of positions within the projection area of said projection optical system.    
     
     
         24 . The exposure apparatus according to claim  23 , further comprising 
 a measurement device, which is arranged on an image plane side of said projection optical system, measuring a coma characteristic of a projection image at each of a plurality of positions within the projection area.    
     
     
         25 . The exposure apparatus according to  claim 23 , further comprising 
 an image plane curvature correction member, which is arranged between the mask and the substrate, correcting non-linear image plane curvature at each of a plurality of positions within the projection area of said projection optical system.    
     
     
         26 . The exposure apparatus according to  claim 23 , further comprising 
 a distortion correction member, which is arranged between the mask and the substrate, respectively correcting non-linear distortions of respective projection images at a plurality of positions within the projection area of said projection optical system.    
     
     
         27 . A projection exposure apparatus which scan-exposes a substrate with a pattern on a mask, comprising: 
 a projection optical system having a predetermined image formation characteristic;    a driving mechanism which moves the mask and the substrate in a one-dimensional scanning direction for said projection optical system;    a restricting mechanism that restricts an image of the pattern, which is projected on an image plane side of said projection optical system, to within a projection area having a predetermined width in the one-dimensional scanning direction; and    at least one optical correction element which is arranged within said projection optical system, and is optically processed to correct an average vector obtained by averaging image distortion vectors at a plurality of image points existing along the one-dimensional scanning within the projection area at each of a plurality of positions in a non-scanning direction intersecting the one-dimensional scanning direction within the projection area.    
     
     
         28 . The apparatus according to  claim 27 , wherein 
 said optical correction element is arranged in a telecentric space where a principal ray becomes almost vertical to an object plane or an image plane of said projection optical system in an image formation optical path of said projection optical system.    
     
     
         29 . The apparatus according to  claim 28 , wherein 
 said optical correction element is made of a transparent optical glass material arranged at least one of the object plane side and the image plane side, and a surface portion corresponding to the projection area of the transparent optical glass material is optically processed to have a locally different surface shape in order to make the average vector at each of the plurality of positions in the non-scanning direction almost identical.    
     
     
         30 . The apparatus according to  claim 29 , wherein 
 the transparent optical glass material is held in a state of being parallel to the object plane or the image plane of said projection optical system, or a state of being tilted relative to the object plane or the image plane.    
     
     
         31 . The apparatus according to  claim 29 , wherein 
 a surface of the transparent optical glass material is optically processed to have a locally different surface shape so that directionality and absolute values of the average vectors at the plurality of positions in the non-scanning direction are approximated to a predetermined function.    
     
     
         32 . The apparatus according to  claim 29 , wherein 
 a surface shape of a surface of the transparent optical glass material is optically and locally processed so that a random error component obtained by removing a linear error component from the average vector at each of the plurality of positions in the non-scanning direction is within ±(Δr/10), if a minimum size of a pattern image which can be resolved on the image plane side through said projection optical system is Δr.    
     
     
         33 . A scanning exposure method in which a substrate is exposed by projecting an image of a pattern formed on an original onto the substrate through a projection optical system, comprising: 
 arranging the original on an object plane side of the projection optical system;    arranging the substrate on an image plane side of the projection optical system; and    moving the original and the substrate in a one-dimensional scanning direction in a state where a partial image of the original is restricted to within a projection area having a predetermined width in the one-dimensional scanning direction, wherein    at least one optical correction element that is optically processed so that an average vector, which is obtained by averaging image distortion vectors at a plurality of image points existing along the one-dimensional scanning within the projection area becomes a predetermined state at each of a plurality of positions in a non-scanning direction intersecting the one-dimensional scanning direction within the projection area, is arranged in an image formation optical path of the projection optical system.    
     
     
         34 . The method according to  claim 33 , wherein: 
 the original is defined to be a mask on which a pattern for manufacturing a circuit device is formed;    the substrate is defined to be a semiconductor wafer coated with a resist;    the projection optical system comprising the optical correction element is defined to be a reduction projection system configured only by a dioptric element, by a combination of a dioptric element and a catoptric element, or only by a catoptric element; and    a circuit device is formed on the semiconductor wafer by projecting the image of the pattern of the mask onto the semiconductor wafer by using the reduction projection system.    
     
     
         35 . The method according to  claim 34 , wherein 
 the optical correction element comprises a correction plate which is arranged on the object side of the projection optical system and corrects a dynamic distortion characteristic defined by the average vector.    
     
     
         36 . The method according to  claim 34 , wherein 
 the optical correction element comprises a correction plate which is arranged on the image plane side of the projection optical system and corrects a dynamic astigmatism aberration characteristic defined by the average vector.    
     
     
         37 . The method according to  claim 34 , wherein 
 the optical correction element is manufactured by optically and locally polishing a surface so that the average vector is approximated to a predetermined function according to a position in the non-scanning direction, or approximated to be almost constant regardless of the position.    
     
     
         38 . A method for adjusting an exposure apparatus in which a substrate is scan-exposed by irradiating a pattern area on a mask by illumination energy from an illumination system, and by moving the mask and the substrate one-dimensionally for a projection optical system while projecting an image of the pattern onto the substrate through the projection optical system, the method comprising: 
 a first step of arranging a first correction member within the illumination system for correcting an optical aberration of the illumination energy on an object plane side or an image plane side of the projection optical system;    a second step of projecting respective images of a plurality of measurement marks on the image plane side of the projection optical system by arranging a test reticle, on which the plurality of measurement marks are formed at respective ideal lattice points or points conforming to the ideal lattice points, on the object plane side of the projection optical system, and by irradiating the illumination energy in an aberration state corrected by said first step on the test reticle; and    a third step of measuring a static image distortion amount included in respective projection images of the measurement marks, and of determining, for each predetermined position in a non-scanning direction, a dynamic image distortion amount based on the measured static image distortion amount which is averaged at the time of scanning exposure; and    a fourth step of arranging a second correction member, which is processed to correct at least a random component of the dynamic image distortion amount, between the object plane and the image plane of the projection optical system.    
     
     
         39 . The method according to  claim 38 , wherein 
 the first correction member corrects an aberration caused by at least one of an entire telecentric error of the illumination energy irradiated on the mask or the test reticle, a local telecentric error, and an error of an illumination numerical aperture varying according to a position within a field of the projection optical system.    
     
     
         40 . The method according to  claim 38 , wherein 
 the second correction member comprises an astigmatism correction plate or an image plane curvature correction plate, which is arranged in a neighborhood of the image plane in a projection optical path of the projection optical system, and a surface of which is locally polished to correct an astigmatism aberration characteristic or an image plan curvature characteristic identified based on the static image distortion amount measured in said third step.    
     
     
         41 . The method according to  claim 38 , wherein 
 the second correction member comprises a distortion correction plate which is arranged in a neighborhood of the object plane side in a projection optical path of the projection optical system, and a surface of which is locally polished to correct a dynamic distortion characteristic identified based on the dynamic image distortion amount determined in said third step.    
     
     
         42 . A scanning exposure method in whith a substrate is exposed by moving a mask and the substrate in respective directions, and by projecting an image of the pattern formed on the mask onto the substrate, the method comprising: 
 a first step of performing scanning exposure wherein respective projection images of a plurality of measurement marks formed on a mask are projected onto a substrate through a projection optical system;    a second step of measuring, as a dynamic aberration error, each deviation amount from ideal positions of the images of the measurement marks formed on the substrate in said first step;    a third step of calculating an average aberration error by adding and averaging measured aberration errors for respective measurement points existing in sequence in a scanning direction; and    a fourth step of inserting at least one optical correction member processed based on the calculated average aberration error in a projection optical path between an object plane and an image plane of the projection optical system.    
     
     
         43 . A scanning exposure method in whith a substrate is exposed by moving a mask and the substrate in respective directions, and by projecting an image of the pattern formed on the mask onto the substrate, the method comprising: 
 a first step of exposing a substrate by projecting projection images of a plurality of measurement marks formed on a mask onto the substrate through a projection optical system in a state where the substrate is substantially stationary;    a second step of measuring each deviation amount from an ideal position of the image of the measurement mark formed on the substrate in said first step;    a third step of calculating an average deviation amount by adding and averaging measured deviation amounts for respective measurement points existing in sequence in a scanning direction; and    a fourth step of inserting at least one optical correction member, which is processed based on the calculated average deviation amount, in a projection optical path between an object plane and an image plane of the projection optical system.    
     
     
         44 . A scanning exposure method in whith a substrate is exposed by moving a mask and the substrate in respective directions, and by projecting an image of the pattern formed on the mask onto the substrate, the method comprising: 
 a first step of photoelectrically detecting respective projection images of a plurality of measurement marks, which are arranged in scanning and non-scanning directions on the mask, on an image plane side of a projection optical system, and of measuring each deviation amount from ideal positions of the projection images of the measurement marks;    a second step of calculating an average deviation amount by adding and averaging deviation amounts measured in said first step for the respective measurement marks existing in the scanning direction among the plurality of measurement marks; and    a third step of inserting at least one optical correction member, which is processed based on the calculated average deviation amount, in a projection optical path between an object plane and the image plane of the projection optical system.    
     
     
         45 . The method according to  claim 44 , wherein 
 said first step is executed by using a detector mounted on a portion of a substrate stage which holds the substrate and is movable.