Exposure method and projection exposure apparatus

Abstract

A projection exposure apparatus carries out scan exposure with illumination flux of slit(s) by moving a mask and a substrate in a direction of one-dimension at synchronized speeds with each other. The mask is inclined with a predetermined angle relative to the substrate in the direction of one-dimensional movement. The substrate is also moved in a direction of optical axis of projection optical system when moved in the direction of one-dimension, such that a central part of transfer area on the substrate is located on a best focal plane of projection optical system upon scan exposure.

What is claimed is:  
     
       1. A method for exposure in which a pattern formed in a transfer region on a mask is subject to projection exposure through a projection optical system to be led onto an area to be exposed on a photosensitive substrate, and said mask and photosensitive substrate are at least one-dimensionally, relatively scanned with respect to a projection field of said projection optical system: comprising, 
       limiting a width of said area of pattern image projected on said photosensitive substrate through the projection optical system to an approximately constant value in a direction of one-dimensional scan; and  
       inclining a local surface on said photosensitive substrate on which said pattern image is formed, relative to a best focal plane of said projection optical system in the direction of one-dimensional scan.  
     
     
       2. A method for exposure according to  claim 1 , wherein a central part of said local surface in the direction of one-dimensional scan on said photosensitive substrate, on which said pattern image is formed, substantially coincides with said best focal plane of projection optical system when scanned for exposure. 
     
     
       3. A method for exposure according to  claim 1 , wherein, defining a width of local surface on the photosensitive substrate in the direction of one-dimensional scan, on which said pattern image is formed as D ap , an angle of inclination between said local surface and said best focal plane as θ 1 , and a depth of focus of said projection optical system in a direction of optical axis as ΔZ f , the following relation is satisfied by adjusting at least one of said width D ap  of the pattern image area and said inclination angle θ 1 ; 
       
         
           D ap ·sin θ 1 ≧Z f .  
         
       
     
     
       4. A method for exposure according to  claim 1 , wherein, the order to limit said width of pattern image area in the direction of one-dimensional scan, a shape of illumination flux for exposure is made rectangular on said mask to be illuminated thereby, and an intensity distribution of said rectangular illumination flux has at least two peaks in the direction of one-dimensional scan. 
     
     
       5. A projection exposure apparatus comprising: 
       a projection optical system for projecting a pattern formed in a transfer region on a mask, onto an area to be exposed on a photosensitive substrate;  
       a mask stage for one-dimensionally moving said mask over a region beyond a width of said transfer region in a direction of movement;  
       a substrate stage for one-dimensionally moving said photosensitive substrate in the direction of one-dimensional movement of said mask stage at a speed synchronized with a movement speed of said mask stage;  
       illumination means for illuminating said mask with an illumination flux for exposure, having a shape between a rectangle and a slit within the projection field of said projection optical system and having an approximately constant width in the direction of one-dimensional movement;  
       a substrate holder the holding said photosensitive substrate on said substrate stage with a predetermined inclination angle with respect to the direction of one-dimensional movement of illuminated area formed by said illumination flux on said photosensitive substrate through said mask and said projection optical system;  
       holder drive means for moving said substrate holder in a direction of optical axis of said projection optical system such that a central part of said illuminated area on said photosensitive substrate is located near a best focal plane of said projection optical system; and  
       control means for controlling said holder drive means to maintain an imaging condition of pattern image of said mask on said photosensitive substrate with correspondence to a position in said illuminated area in the direction of one-dimensional movement while scan exposure of pattern of said mask is effected on said area to be exposed.  
     
     
       6. A scanning exposure method of exposing a substrate through a projection optical system with an energy beam irradiated on a mask, comprising: 
       
         distributing the energy beam within a field of view of the projection optical system within a plurality of regions extending in a second direction crossing a first direction in which the substrate is moved during scanning exposure of the substrate, and  
       
       
         moving the substrate relative to the plurality of regions in the first direction in synchronization with movement of the mask during the scanning exposure. 
       
     
     
       7. A method according to  claim 6 , wherein the projection optical system has a circular field of view and the plurality of regions respectively extend across the circular field of view. 
     
     
       8. A method according to  claim 7 , wherein the plurality of regions include a first region separated from a center of the circular field of view of the projection optical system in the first direction. 
     
     
       9. A method according to  claim 8 , wherein the plurality of regions include a second region separated from the center of the circular field of view of the projection optical system on a side opposite to the first region. 
     
     
       10. A method according to  claim 9 , wherein the plurality of regions include a third region substantially disposed at the center of the circular field of view. 
     
     
       11. A method according to  claim 7 , wherein the plurality of regions include a region with a center substantially coincident with an optical axis of the projection optical system in the circular field of view. 
     
     
       12. A method according to  claim 7 , wherein each of the plurality of regions is substantially rectangular and substantially orthogonal to the first direction. 
     
     
       13. A method according to  claim 12 , wherein the projection optical system has a reduction magnification and the mask and the substrate are moved at different speeds during the scanning exposure. 
     
     
       14. A method according to  claim 13 , wherein the mask and the substrate are respectively moved at a speed ratio corresponding to the magnification of the projection optical system, and substantially at a constant speed, during the scanning exposure. 
     
     
       15. A method according to  claim 6 , wherein an intensity distribution of the energy beam is adjusted within an illumination optical system, which irradiates the energy beam on the mask, in order to distribute the energy beam within the plurality of regions. 
     
     
       16. A method according to  claim 15 , wherein the illumination optical system has an optical integrator and adjusts the intensity distribution between the optical integrator and the mask. 
     
     
       17. A method according to  claim 16 , wherein the intensity distribution is adjusted by a mask blade disposed within the illumination optical system. 
     
     
       18. A method according to  claim 6 , further comprising: 
       
         adjusting a relative inclination and position between an image plane of the projection optical system and the substrate so that the image plane and the substrate are substantially coincided within the range of a focal depth of the projection optical system during the scanning exposure. 
       
     
     
       19. A method according to  claim 6 , further comprising: 
       
         controlling a focus operation with respect to the substrate so that the substrate is maintained within the range of a focal depth of the projection optical system within at least one region among the plurality of regions during the scanning exposure. 
       
     
     
       20. A method according to  claim 19 , wherein respective positional relationships between the image plane of the projection optical system within the plurality of regions and the substrate are made to be different during the scanning exposure. 
     
     
       21. A method according to  claim 6 , further comprising: 
       
         changing a position of a specified point on the substrate with respect to a direction along an optical axis of the projection optical system in each of the plurality of regions when the specified point crosses each of the plurality of regions during the scanning exposure. 
       
     
     
       22. A method according to  claim 6 , further comprising: 
       
         causing an exposure amount to be seamless by performing overlapping exposure within a shot area on the substrate to which a pattern of the mask is transferred when the shot area is larger than the plurality of regions with respect to the second direction. 
       
     
     
       23. A method of fabricating a device, the method comprising transferring, utilizing the scanning exposure method of  claim 6 , respective device patterns provided on the mask to a plurality of shot areas provided on the substrate. 
     
     
       24. A scanning exposure method of exposing a substrate through a projection optical system with an energy beam irradiated on a mask, comprising: 
       
         moving the substrate relative to the energy beam projected by the projection optical system in synchronization with movement of the mask relative to the energy beam during scanning exposure of the substrate with the energy beam, and  
       
       
         changing a position of a specified point on the substrate with respect to a direction along the optical axis of the projection optical system during the scanning exposure so that the energy beam is irradiated on the specified point at a plurality of different positions along the optical axis. 
       
     
     
       25. A method according to  claim 24 , wherein the position of the specified point is changed within a range of a depth of focus of the projection optical system. 
     
     
       26. A method of fabricating a device, the method comprising transferring, utilizing the scanning exposure method of  claim 24 , a device pattern provided on the mask to each of a plurality of shot areas provided on the substrate. 
     
     
       27. A scanning exposure method comprising: 
       
         defining an irradiation region of illumination light on a substrate to a rectangular or slit shape for a scanning exposure of the substrate with the illumination light through a mask and a projection optical system;  
       
       
         moving the substrate relative to the illumination light, which passes through the projection optical system, in synchronization with movement of the mask relative to the illumination light during the scanning exposure;  
       
       
         detecting positional information of the substrate with respect to a direction along an optical axis of the projection optical system within the irradiation region of the illumination light; and  
       
       
         irradiating the illumination light onto a specified point on the substrate at a plurality of positions in the direction within a depth of focus of the projection optical system, based upon the detection positional information during the scanning exposure. 
       
     
     
       28. A method according to  claim 27 , wherein the positional information of the substrate is detected by projecting a detection beam within the irradiation region of the illumination light. 
     
     
       29. A method according to  claim 27 , wherein the positional information of the substrate includes leveling information relating to an inclination of the substrate. 
     
     
       30. A method according to  claim 27 , wherein the projection optical system includes refractive elements only or a combination of refractive elements and reflective elements. 
     
     
       31. A method according to  claim 27 , wherein the projection optical system is telecentric on both a mask side and a substrate side. 
     
     
       32. A method according to  claim 27 , wherein the projection optical system is a reduction optical system with a circular field of view. 
     
     
       33. A method according to  claim 27 , wherein the irradiation region of the illumination light includes an optical axis of the projection optical system. 
     
     
       34. A method according to  claim 27 , wherein a plurality of the irradiation regions of the illumination light are formed in the moving direction of the substrate. 
     
     
       35. A method of fabricating a device, the method comprising transferring, utilizing the scanning exposure method of  claim 27 , a device pattern provided on the mask to each of a plurality of shot areas provided on the substrate. 
     
     
       36. A scanning exposure apparatus which moves a mask and a substrate relative to an energy beam during scanning exposure of the substrate with the energy beam through the mask, comprising: 
       
         a projection optical system disposed on an optical path along which the energy beam passes; and  
       
       
         an illumination optical system disposed on an object plane side of the projection optical system, the illumination optical system distributing the energy beam within a plurality of regions being arranged in a first direction in which the substrate is moved during the scanning exposure and extending in a second direction crossing the first direction in a field of view of the projection optical system. 
       
     
     
       37. An apparatus according to  claim 36 , wherein the projection optical system has a circular field of view and the illumination optical system defines each of the respective plurality of regions to have a rectangular shape that extends across the circular field of view. 
     
     
       38. An apparatus according to  claim 37 , wherein the plurality of regions include a first region separated from a center of the circular field of view of the projection optical system in the first direction. 
     
     
       39. An apparatus according to  claim 38 , wherein the plurality of regions include a second region separated from the center of the circular field of view on a side opposite to the first region. 
     
     
       40. An apparatus according to  claim 39 , wherein the plurality of regions include a third region substantially disposed at the center of the circular field of view. 
     
     
       41. An apparatus according to  claim 37 , wherein the plurality of regions include a region with a center substantially coincident with an optical axis of the projection optical system in the circular field of view. 
     
     
       42. An apparatus according to  claim 36 , wherein: 
       
         the projection optical system is a telecentric reduction system; and  
       
       
         further comprising a scanning system having a mask stage disposed on the object plane side of the projection optical system and a substrate stage disposed on an image plane side of the projection optical system, wherein the scanning system moves the mask and the substrate at different speeds during the scanning exposure, and, respectively, at substantially a constant speed. 
       
     
     
       43. An apparatus according to  claim 42 , further comprising: 
       
         an adjusting system connected to the scanning system, the adjusting system adjusting a relative inclination and position between the image plane of the projection optical system and the substrate so that the image plane and the substrate are substantially coincided within the range of a focal depth of the projection optical system during the scanning exposure. 
       
     
     
       44. An apparatus according to  claim 43 , wherein the adjusting system changes a position of a specified point on the substrate with respect to a direction along an optical axis of the projection optical system in each of the plurality of regions when the specified point crosses each of the plurality of regions during the scanning exposure. 
     
     
       45. An apparatus according to  claim 42 , further comprising: 
       
         a controller connected to the scanning system, wherein the controller causes the exposure amount to be seamless by performing overlapping exposure within a shot area on the substrate to which a mask pattern is transferred, when the shot area is larger than the plurality of regions with respect to the second direction. 
       
     
     
       46. An apparatus according to  claim 36 , wherein the illumination optical system includes an optical integrator, and an intensity distribution of the energy beam is adjusted between the optical integrator and the mask in order to distribute the energy beam in the plurality of regions. 
     
     
       47. An apparatus according to  claim 46 , wherein the illumination optical system includes a mask blade disposed substantially conjugate to the mask in order to adjust the intensity distribution. 
     
     
       48. A method of fabricating a device, the method comprising transferring, utilizing the scanning exposure apparatus of  claim 36 , respective device patterns provided on the mask to a plurality of shot areas provided on the substrate.