Projection optical apparatus using plural wavelengths of light

Abstract

A projection optical apparatus comprising a projection optical system for projectively focusing a pattern image of a mask under illumination by light of first wavelength onto a sensitive substrate, a stage holding the sensitive substrate, a fiducial plate disposed on the stage, a first mark detector for illuminating light of second wavelength different from the first wavelength, through a first mark area formed on the mask and the projection optical system, onto .[.the sensitive substrate or.]. a second mark area formed on the fiducial plate, then detecting optical information produced from the second mark area, a fourth mark area formed on .[.the sensitive substrate or.]. the fiducial plate and arranged in a predetermined positional relationship relative to the second mark area, a third mark area formed on the mask and arranged in a predetermined positional relationship relative to the first mark area, a second mark detector for illuminating the light of first wavelength onto the fourth mark area through the third mark area and the projection optical system, and then detecting optical information produced from the fourth mark area, under a condition that the first mark detector is detecting the optical information produced from the second mark area, and an error detector for detecting detection errors due to a distortion at respective positions in the view field of the projection optical system where the first mark area and the second mark area are present, based on the detected results by the first mark detector and the second mark detector.

I claim: 
     
       1. A projection optical apparatus comprising: a projection optical system for projectively focusing a pattern image of a mask under illumination by a light of first wavelength characteristic onto a sensitive substrate,   a stage for holding said sensitive substrate,   a fiducial plate disposed on said stage,   first mark detection means for illuminating a light of second wavelength characteristic different from said first wavelength characteristic, through a first mark area formed on said mask and said projection optical system, onto .[.said sensitive substrate or.]. a second mark area formed on said fiducial plate, and then detecting optical information produced from said second mark area,   a fourth mark area formed on .[.said sensitive substrate or.]. said fiducial plate and arranged in a predetermined positional relationship relative to said second mark area,   a third mark area formed on said mask and arranged in a predetermined positional relationship relative to said first mark area,   second mark detection means for illuminating said light of first wavelength characteristic onto said fourth mark area through said third mark area and said projection optical system, and then detecting optical information produced from said fourth mark area, under a condition that said first mark detection means is detecting the optical information produced from said second mark area, and   error detection means for detecting detection errors due to a distortion at respective positions in the view field of said projection optical system where said first mark area and said second mark area are present, based on the detected results by said first mark detection means and said second mark detection means.   
     
     
       2. A projection optical apparatus according to claim 1, wherein: said first mark detection means has a first object lens system movable depending on position change of said first mark area on said mask, and   .[.the.]. .Iadd.a .Iaddend.uniform mark pattern is formed in said second mark area over a movable range of said first object lens system.   
     
     
       3. A projection optical apparatus comprising: a projection optical system disposed between first and second planes such that said first and second planes are optically conjugate to each other under a first wavelength characteristic,   alignment mark means including first and third mark means disposed on said first plane with a predetermined positional relationship therebetween, and second and fourth mark means disposed on said second plane with a predetermined positional relationship therebetween;   first mark detection means for illuminating a light of second wavelength characteristic different from said first wavelength characteristic onto said second mark means through said first mark means and said projection optical system, and then detecting first optical information produced from said second mark means,   second mark detection means for illuminating said light of first wavelength characteristic onto said fourth mark means through said third mark means and said projection optical system, and then detecting second optical information produced from said fourth mark means, and   means for creating information of alignment errors developed between said first and second planes in the directions enough to define a plane, based on said first and second optical information. .Iadd.   
     
     
       4.  A projection exposure apparatus for exposing a pattern area of a mask irradiated with first illumination light onto a substrate through a projection optical system, the apparatus comprising: (a) a movable stare supporting the substrate and moving in a predetermined plane perpendicular to an optical axis of said projection optical system;   (b) a mask holder supporting the mask which has a mask mark formed at a peripheral position of the pattern area;   (c) a fiducial plate mounted on said movable stage and having first and second fiducial marks on its top face, the first fiducial mark being aligned through said projection optical system with the mask mark when said movable stage is located at a predetermined reference position with respect to the image field of said projection optical system;   (d) a first alignment system irradiating the mask mark and the first fiducial mark with the first illumination light and receiving a light from the mask mark and a light from the first fiducial mark through said projection optical system, to detect a positional relationship between the mask mark and the first fiducial mark, when said movable stage is; located near the reference position; and   (e) a second alignment system including a predetermined detecting reference, irradiating the second fiducial mark with second illumination light which has different wavelength from the first illumination light and receiving a light from the second fiducial mark through said projection optical system, to detect a positional relationship between the detecting reference and the second fiducial mark, when said movable stage is located near the reference position..Iaddend..Iadd.5. A projection exposure apparatus for exposing a pattern area of a mask irradiated with first illumination light onto a substrate through a projection optical system, the apparatus comprising:   (a) a movable stage supporting the substrate and moving in a plane perpendicular to an optical axis of said projection optical system;   (b) a fiducial plate fixedly mounted on a portion of said movable stage and having first and second fiducial patterns on its surface, said first and second fiducial patterns being arranged with predetermined positional relationship;   (c) a first alignment optical system detecting a light from said first fiducial pattern through said projection optical system and a peripheral portion of the pattern area of said mask and a light from a mask mark formed within the peripheral portion of said mask, when said mask mark and the first fiducial pattern are irradiated with a light of a same wavelength as the first illumination light;   (d) a controller driving and positioning said movable stage so that the first fiducial pattern is substantially aligned with the mask mark and simultaneously the second fiducial pattern is located at a predetermined position in the image field of said projection optical system; and   (e) a second alignment optical system detecting a light from the second fiducial pattern through said projection optical system, when the second fiducial pattern is irradiated with a light having different wavelength than the first illumination light;   wherein said movable stage is stationary until said first and second alignment optical systems complete the light detecting   
     
     
        operations..Iaddend..Iadd.6.  A method for examining a variation of the base line distance between a center point of a reticle and a detecting center of an alignment system which detects positional deviation of a mark formed on a substrate for aligning the substrate through a projection optical system, the method comprising the steps of: (a) providing a fiducial plate within the image field of said projection optical system instead of the substrate, said fiducial plate having a first fiducial mark to be aligned with a reticle mark through said projection optical system and a second fiducial mark disposed at a predetermined positional relationship with respect to the first fiducial mark;   (b) positioning said fiducial plate at a reference position so that the first fiducial mark and the reticle mark are substantially aligned with each other through said projection optical system; and   (c) detecting the positional deviation between the detecting center of said alignment system and the second fiducial mark to determine the variation of said base line distance while said fiducial plate is stationary at the   
     
     
        reference position..Iaddend..Iadd.7.  A method for aligning a substrate and a mask having a circuit pattern, and for exposing a an image of the circuit pattern onto the substrate through a projection optical system, the method comprising the steps of: (a) detecting a mask mark formed on the mask and a first fiducial mark disposed on a movable stage through said projection optical system with a first alignment system using a first wavelength of light and, substantially at the same time, detecting a second fiducial mark disposed on said movable stage through said projection optical system with a second alignment system using a different wavelength of light, when said movable stage is stationary at a baseline measurement position;   (b) determining a positional relationship between a detecting reference of said second alignment system and the circuit pattern of the mask in an image field of said projection optical system based on detection results obtained in step (a);   (c) detecting an alignment mark formed on the substrate, which is mounted on said movable stage, with said second alignment system;   (d) determining a positional relationship between the detecting reference of paid second alignment system and the alignment mark of the substrate in the image field of said projection optical system based on a detection result obtained in step (c); and   (e) positioning said movable stage to alit a shot area of the substrate and the image of the circuit pattern based on the positional relationships determined in steps (b) and (d), and exposing the shot area of the   
     
     
        substrate..Iaddend..Iadd.8.  A method according to claim 7, wherein, in the step (a), said first alignment system generates a first deviation signal representing a positional relationship of the mask mark and the first fiducial mark and, substantially at the game time, said second alignment system generates a second deviation signal representing a positional relationship of the detecting reference of said second 
     
     
        alignment system and the second fiducial mark..Iaddend..Iadd.9.  A method according to claim 7, wherein the substrate has first and second X-direction alignment marks and first and second Y-direction alignment marks, and said second alignment system includes a first objective lens for detecting the first X-direction aliment mark, a second objective lens for detecting the first Y-direction alignment mark, a third objective lens for detecting the second X-direction alignment mark, and a fourth objective lens for detecting the second Y-direction alignment mark..Iaddend..Iadd.10. A method according to claim 9, wherein the step (c) includes detecting at least one of said first and second X-direction alignment marks and at least one of said first and second Y-direction alignment marks, and the step (d) includes determining positional relationships between the detecting reference of said alignment system and each of said one X-direction alignment mark and said one Y-direction alignment mark..Iaddend..Iadd.11. A method according to claim 7, wherein the steps (a) and (b) are performed after operation of an adjustment unit which adjusts a magnification or a distortion characteristic of said 
     
     
        projection optical system..Iaddend..Iadd.12.  A projection exposure apparatus comprising: a projection optical system disposed between a mask and a substrate to project on the substrate an illumination light irradiating the mask;   a plate having fiducial marking formed thereon and disposed in an image field of said projection optical system;   a first alignment system irradiating a portion of said fiducial marking with a first alignment light different from said illumination light in wavelength to detect optical information produced from said fiducial marking through said projection optical system;   a second alignment system irradiating a portion of said fiducial marking with a second alignment light having substantially the same wavelength as said illumination light through said projection optical system to detect a positional relationship between said mask and said plate; and   an alignment controller connected to said first and second alignment systems to detect an offset amount of said first alignment system caused   
     
     
        by said projection optical system..Iaddend..Iadd.13.  An apparatus according to claim 12, wherein said fiducial marking includes two mark patterns disposed at a predetermined positional relationship so that said two mark patterns are detected substantially at the same time by said first and second alignment systems, respectively..Iaddend..Iadd.14. An apparatus according to claim 12, wherein   said first alignment system includes a photodetector which receives, through a mark area on said mask, diffraction light produced from said fiducial marking and passing through said projection optical system..Iaddend..Iadd.15. An apparatus according to claim 12, further comprising:   an adjustment unit connected to said projection optical system to adjust an optical characteristic of said projection optical system,   wherein said alignment controller determines the offset amount of said first alignment system after an adjustment of said optical characteristic..Iaddend..Iadd.16. A projection exposure apparatus comprising:   a projection optical system disposed between a mask and a substrate to project on the substrate an illumination light irradiating the mask;   a first alignment system irradiating a first fiducial mark with a first alignment light different from said illumination light in wavelength to detect optical information produced from said first fiducial mark through said projection optical system;   a second alignment system irradiating a second fiducial mark with a second alignment light having substantially the same wavelength as said illumination light through said projection optical system to detect a positional relationship between said second fiducial mark and a mark on said mask; and   a plate disposed on a substrate side with respect to said projection optical system, said first and second fiducial marks being formed on said plate at a predetermined positional relationship so that said first and second alignment systems respectively detect said first and second   
     
     
        fiducial marks substantially at the same time..Iaddend..Iadd.17.  An apparatus according to claim 16, further comprising: an alignment controller connected to said first and second alignment systems to determine a base line amount of said first alignment system..Iaddend..Iadd.18. A projection exposure method for protecting an illumination light irradiating a mask through a projection optical system on a substrate to transfer a pattern of said mask onto said substrate, comprising the steps of:   disposing a plate formed with a first fiducial mark and a second fiducial mark in an image field of said projection optical system;   detecting said first fiducial mark through said projection optical system by a first alignment system which uses a first beam different from said illumination light in wavelength;   detecting said second fiducial mark through said projection optical system by a second alignment system which uses a second beam having substantially the same wavelength as said illumination light; and   determining a base line amount of said first alignment system based on outputs of said first and second alignment systems..Iaddend..Iadd.19. A method according to claim 18, wherein   said step of detecting said first fiducial mark by said first alignment system and said step of detecting said second fiducial mark by said second alignment system are performed substantially at the same time..Iaddend..Iadd.20. A method according to claim 19, wherein   said plate is substantially at rest during said steps of detecting said first and second fiducial marks..Iaddend..Iadd.21. A method according to claim 18, wherein   said base line amount of said first alignment system is determined after an adjustment of an optical characteristic of said projection optical system or a position of said first alignment system..Iaddend..Iadd.22. A projection exposure method for protecting an illumination light irradiating a mask through a projection optical system on a substrate to transfer a pattern of said mask on said substrate, comprising the steps of:   disposing a plate formed with fiducial marking in an image field of said projection optical system;   detecting said fiducial marking through said projection optical system by a first alignment system which uses a first beam different from said illumination light in wavelength and by a second alignment system which uses a second beam having substantially the same wavelength as said illumination light, respectively; and   determining a base line amount of said first alignment system based on outputs of said first and second alignment systems..Iaddend.