Scanning exposure apparatus

Abstract

A projection exposure apparatus for transferring a pattern formed on a mask onto a photosensitive substrate by a scanning exposure method, includes a light source for generating a light beam having a predetermined spatial coherence, an illumination optical system for receiving the light beam from the light source and illuminating a local area on the mask with the light beam, and a device for synchronously moving the mask and the photosensitive substrate so as to transfer the pattern on the mask onto the photosensitive substrate. A direction, corresponding to a higher spatial coherence of the light beam, is made to coincide with the direction of relative scanning an illumination area and the mask in the illumination area.

What is claimed is:  
     
       1. A scanning exposure apparatus comprising: 
       a light source for emitting a spatially coherent light beam;  
       an illumination optical system for radiating the light beam from said light source onto a mask so as to form an illumination area on a local area of the mask, said light beam having higher spatial coherence in one direction than in another direction of a cross-section of the beam in the illumination area; and  
       a device for synchronously moving the mask and a photosensitive substrate so as to transfer a pattern formed on the mask onto the photosensitive substrate,  
       wherein a direction of relative scanning of the illumination area and the mask upon movement of the mask substantially coincides with the direction with higher spatial coherence of the light beam.  
     
     
       2. An apparatus according to claim  1 , wherein said light source comprises a pulse oscillation type laser light source for emitting a light beam in a deep ultraviolet range. 
     
     
       3. An apparatus according to claim  1 , further comprising: 
       a projection optical system for projecting an image of the pattern in the illumination area onto photosensitive substrate,  
       wherein said moving device comprises a mask stage which holds the mask to be substantially perpendicular to an optical axis of said projection optical system, and moves substantially along the direction with the higher spatial coherence of the light beam, and a substrate stage which holds the photosensitive substrate and moves in a direction substantially perpendicular to the optical axis of said projection optical system.  
     
     
       4. An apparatus according to claim  1 , further comprising: 
       an optical member for receiving the light beam from said light source, and shifting an interference pattern formed in the illumination area in a direction substantially perpendicular to the direction of relative scanning.  
     
     
       5. An apparatus according to claim  4 , wherein said illumination optical system comprises an optical integrator for receiving the light beam, and forming a plurality of light source images, and 
       said optical member changes an incident angle of the light beam or said optical integrator.  
     
     
       6. An apparatus according to claim  1 , further comprising: 
       a device for shifting an interference pattern in the illumination area along the direction of relative scanning in accordance with a moving speed of the mask and an intensity distribution, in the direction of relative scanning, of the interference pattern.  
     
     
       7. An apparatus according to claim  6 , further comprising: 
       a device for detecting spatial coherence of the light beam by receiving at least a portion of the light beam from said light source; and  
       a controller for controlling an operation of said shifting device in accordance with the detected spatial coherence.  
     
     
       8. A scanning exposure apparatus comprising: 
       a light source for emitting a spatially coherent light beam;  
       an illumination optical system for radiating the light beam from said light source onto a mask so as to form an illumination area on a local area of the mask;  
       a device for synchronously moving the mask and a photosensitive substrate so as to transfer a pattern formed on the mask onto the photosensitive substrate; and  
       a device for shifting an interference pattern in the illumination area in accordance with a moving speed of the mask and an intensity distribution of the interference pattern while the mask and the photosensitive substrate are being synchronously moved.  
     
     
       9. An apparatus according to claim  8 , wherein the light beam has higher spatial coherence in one direction than in another direction of a cross-section of the beam in the illumination area, said moving device comprises a mask stage which holds the mask and moves substantially along the direction with higher spatial coherence of the light beam, and a substrate stage which holds the photosensitive substrate and is movable in synchronism with movement of said mask stage. 
     
     
       10. An apparatus according to claim  8 , further comprising: 
       a device for detecting spatial coherence of the light beam by receiving at least a portion of the light beam from said light source; and  
       a controller for controlling an operation of said shifting device in accordance with the detected spatial coherence.  
     
     
       11. A scanning exposure apparatus comprising: 
       a light source for emitting spatially coherent pulsed light;  
       an illumination optical system for radiating the light from said light source onto a mask so as to form an illumination area locally on the mask;  
       a device for synchronously moving the mask and a photosensitive substrate so as to transfer a pattern formed on the mask onto the photosensitive substrate; and  
       a device for shifting an interference pattern formed in the illumination area in a moving direction of the mask,  
       wherein an accumulated light amount on the mask or the photosensitive substrate, upon radiation of a plurality of light pulses from said light source onto said mask, is uniformed by operation of said moving device and said shifting device.  
     
     
       12. An apparatus according to claim  11 , wherein said shifting device comprises an optical member for receiving light pulses from said light source and varying a propagation direction of the light pulses, and shifts the interference pattern in the illumination area in the moving direction of the mask and a direction substantially perpendicular to the moving direction. 
     
     
       13. A scanning exposure apparatus comprising: 
       a light source;  
       an illumination optical system for illuminating a mask with a light beam from said light source, said light beam having higher spatial coherence in one direction than in another direction of a cross-section of the beam in an illumination area on the mask;  
       a projection optical system for projecting an image of a pattern formed on the mask onto a photosensitive substrate;  
       a mask stage which holds the mask to be substantially perpendicular to an optical axis of said projection optical system, and which moves substantially along the direction with higher spatial coherence of the light beam;  
       a substrate stage which holds the photosensitive substrate and moves in a direction substantially perpendicular to the optical axis of said projection optical system; and  
       a device for synchronously driving said mask stage and said substrate stage so as to transfer the pattern on the mask onto the photosensitive substrate.  
     
     
       14. An apparatus according to claim  13 , further comprising: 
       a device for shifting an interference pattern formed on the mask in a moving direction of said mask stage or in a direction crossing the moving direction, in association with the movement of said mask stage.  
     
     
       15. A scanning exposure apparatus comprising: 
       a projection optical system for projecting an image of a pattern formed on a mask onto a photosensitive substrate;  
       a device for synchronously moving the mask and the photosensitive substrate along a direction substantially perpendicular to an optical axis of said projection optical system so as to transfer the pattern on the mask onto the photosensitive substrate; and  
       a device for illuminating a local area on the mask with light beam having higher spatial coherence in one direction than in another direction of a cross-section of the beam, such that the direction with higher spatial coherence of the light beam substantially coincides with a moving direction of the mask.  
     
     
       16. An apparatus according to claim  15 , wherein said illuminating device comprises a pulse laser light source for emitting the light beam, an optical member for substantially aligning the direction with higher spatial coherence of the light beam with the moving direction of the mask, a field stop arranged on a plane substantially conjugate with a pattern surface of the mask, and a light transmission system for guiding, to the mask, light which emerges from said optical member and passes through an aperture of said field stop. 
     
     
       17. An apparatus according to claim  16 , further comprising: 
       a device for shifting an interference pattern formed on the mask in the moving direction of the mask or a direction crossing the moving direction.  
     
     
       18. An apparatus for illuminating a mask having a pattern to be transferred onto a photosensitive substrate by a scanning exposure method, comprising: 
       a light source;  
       a device for radiating the light beam from said light source onto the mask via an aperture of a field stop arranged on a plane substantially conjugate with a pattern surface of the mask, said light beam having higher spatial coherence in one direction than in another direction of a cross-section of the beam in an illumination area on the mask; and  
       an optical member for substantially aligning the direction with higher spatial coherence of the light beam with a scanning direction of the mask.  
     
     
       19. A scanning exposure method comprising: 
       
         radiating a spatially coherent light beam onto a mask so as to form an illumination area; and  
       
       
         synchronously moving the mask and a substrate so as to transfer a pattern formed on the mask onto the substrate; and  
       
       
         shifting an interference pattern formed in the illumination area in a moving direction of the mask.  
       
     
     
       20. A scanning exposure method comprising: 
       
         synchronously moving a mask and a substrate so as to transfer a pattern formed on the mask onto the substrate; and  
       
         illuminating the mask with a light beam having higher spatial coherence in one direction than in another direction of a cross - section of the beam, such that the direction with higher spatial coherence of the light beam substantially coincides with a moving direction of the mask.    
     
     
       21. A scanning exposure method comprising: 
       
         moving, during a scanning exposure, a mask and an object relative to an exposure beam to expose the object with a pattern formed on the mask; and  
       
       
         directing the exposure beam to an irradiation area during the scanning exposure, the mask moving relative to the irradiation area, in a scanning direction during the scanning exposure,  
       
       
         wherein the exposure beam has higher spatial coherence in one direction than in another direction, and wherein said one direction substantially coincides with the scanning direction.  
       
     
     
       22. A method according to claim  21 , further comprising: 
       
         shifting an interference pattern formed in the irradiation area to which the exposure beam is directed.  
       
     
     
       23. A method according to claim  22 , wherein the interference pattern is shifted in accordance with a relative velocity of said mask and said exposure beam.  
     
     
       24. A method according to claim  22 , wherein the interference pattern is shifted in accordance with an intensity distribution of the interference pattern.  
     
     
       25. A method according to claim  22 , wherein the interference pattern is shifted in the scanning direction.  
     
     
       26. A method according to claim  22 , wherein the interference pattern is shifted in a direction transverse to the scanning direction.  
     
     
       27. A method according to claim  26 , wherein said direction transverse to the scanning direction includes a direction perpendicular to the scanning direction.  
     
     
       28. A scanning exposure apparatus in which a work- piece is moved in a scanning direction relative to an exposure beam during a scanning exposure, comprising:    
         a projection system, disposed in a path of said exposure beam, which projects a pattern image onto the work - piece, the exposure beam having higher spatial coherence in one direction than in another direction; and    
         an optical system, disposed in the path of said exposure beam, which directs said exposure beam to said work - piece such that said one direction substantially coincides with the scanning direction.    
     
     
       29. A scanning exposure apparatus according to claim  28 , further comprising: 
       
         a shifting member, disposed in the path of said exposure beam, which shifts an interference pattern formed in an irradiation area of the exposure beam during the scanning exposure.  
       
     
     
       30. An apparatus according to claim  29 , wherein said shifting member shifts the interference pattern in the scanning direction.  
     
     
       31. An apparatus according to claim  29 , wherein said shifting member shifts the interference pattern in a direction transverse to the scanning direction.  
     
     
       32. An apparatus according to claim  28 , wherein said optical system includes an optical integrator.  
     
     
       33. A scanning exposure method comprising: 
       
         moving, during a scanning exposure, a mask and an object relative to an exposure beam to expose the object with a pattern formed on the mask;  
       
       
         directing the exposure beam to an irradiation area during the scanning exposure, the mask moving relative to the irradiation area in a scanning direction during the scanning exposure; and  
       
       
         shifting an interference pattern formed in the irradiation area during the scanning exposure.  
       
     
     
       34. A method according to claim  33 , wherein the interference pattern is shifted in the scanning direction.  
     
     
       35. A method according to claim  34 , wherein the interference pattern is shifted in accordance with a relative velocity of said mask and said exposure beam.  
     
     
       36. A method according to claim  34 , wherein said interference pattern is shifted in accordance with an intensity distribution of the interference pattern.  
     
     
       37. A scanning exposure method according to claim  33 , wherein the following condition is satisfied: 
       
         
             V= ( E/Ep ) f·D    
         
       
       
         where,  
       
       
         V: a relative velocity of said mask and said exposure beam;  
       
       
         E: an optimum exposure dose of said mask;  
       
       
         Ep: an average energy of said exposure beam;  
       
       
         D: a width of said irradiation area in the scanning direction;  
       
       
         f: an oscillation frequency of said exposure beam.  
       
     
     
       38. A method according to claim  33 , wherein the interference pattern is shifted in a direction transverse to the scanning direction.  
     
     
       39. A method according to claim  38 , wherein said direction transverse to the scanning direction includes a direction perpendicular to the scanning direction.  
     
     
       40. A method according to claim  33 , wherein the exposure beam has higher spatial coherence in one direction than in another direction, and wherein the interference pattern is shifted in said one direction.  
     
     
       41. A method according to claim  40 , wherein said one direction substantially coincides with the scanning direction.  
     
     
       42. A method according to claim  33 , wherein the interference pattern has lower contrast in one direction than in another direction, and wherein the interference pattern is shifted in said one direction.  
     
     
       43. A method according to claim  42 , wherein said one direction is transverse to the scanning direction.  
     
     
       44. A method according to claim  33 , wherein the interference pattern has higher contrast in one direction than in another direction, and wherein the interference pattern is shifted in said one direction.  
     
     
       45. A method according to claim  44 , wherein said one direction substantially coincides with the scanning direction.  
     
     
       46. A scanning exposure method in which a work- piece to be exposed and an exposure beam are moved relatively during scanning exposure, comprising:    
         determining an exposure condition of the work - piece based on information concerning a divergent angle of said exposure beam; and    
       
         effecting scanning exposure based on the determined exposure condition.  
       
     
     
       47. A method according to claim  46 , wherein said exposure beam is emitted from a beam source of a pulse- oscillation type, and said exposure condition is an oscillation cycle of the exposure beam during the scanning exposure.    
     
     
       48. A method according to claim  46 , wherein said exposure beam is emitted from a beam source of a pulse- oscillation type, and said exposure condition is a number of pulses of the exposure beam with which said work - piece is irradiated.    
     
     
       49. A method according to claim  46 , wherein said exposure condition is a shift condition of an interference pattern formed within an irradiation area of said exposure beam.  
     
     
       50. A method according to claim  46 , wherein said exposure condition is a relative velocity of said exposure beam and said work- piece.    
     
     
       51. A scanning exposure method comprising: 
       
         moving a mask and an object synchronously to expose the object with a pattern formed on the mask during a scanning exposure; and  
       
       
         directing a plurality of exposure beams to an irradiation area during the scanning exposure, the mask moving relative to the irradiation area in a scanning direction during the scanning exposure,  
       
       
         wherein the plurality of exposure beams have illuminance distributions in the scanning direction that are different from each other.  
       
     
     
       52. A method according to claim  51 , wherein said plurality of beams differ in their directions of polarization to each other.  
     
     
       53. A scanning exposure method comprising: 
       
         directing an exposure beam to an irradiation area;  
       
       
         relatively moving an object and the irradiation area for scanning exposure; and  
       
       
         determining whether or not an interference pattern formed with said irradiation area is to be shifted during said scanning exposure.  
       
     
     
       54. A method according to claim  53 , wherein whether or not the interference pattern is to be shifted is determined based on a relative velocity of said irradiation area and said object.  
     
     
       55. A method according to claim  53 , wherein whether or not the interference pattern is to be shifted is determined based on an intensity distribution of the interference pattern.  
     
     
       56. A method according to claim  55 , wherein whether or not the interference pattern is to be shifted is determined based on a value D/NP, 
       
         wherein  
       
       
         D: a width of said irradiation area in a direction of said relative moving;  
       
       
         N: a number of pulses with which a point on said object is to be irradiated;  
       
       
         P: a pitch of said interference pattern.  
       
     
     
       57. A scanning exposure method comprising: 
       
         directing an exposure beam to an irradiation area;  
       
       
         relatively moving an object and the irradiation area in a first direction for scanning exposure; and  
       
       
         shifting an interference pattern formed within the irradiation area in a first direction and a second direction which is transverse to said first direction, during the scanning exposure;  
       
       
         wherein a way of controlling the shift of the interference pattern in said first direction is different from a way of controlling the shift of the interference pattern in said second direction.  
       
     
     
       58. A method of manufacturing a device using an object, comprising: 
       
         moving, during a scanning exposure, a mask and the object relative to an exposure beam to expose the object with a pattern formed on the mask; and  
       
       
         directing the exposure beam to an irradiation area during the scanning exposure, the mask moving relative to the irradiation area in a scanning direction during the scanning exposure,  
       
       
         wherein the exposure beam has higher spatial coherence in one direction than in another direction, and wherein said one direction substantially coincides with the scanning direction.  
       
     
     
       59. A method of manufacturing a device using a work- piece, comprising:    
         providing a scanning exposure apparatus in which a work - piece is moved in a scanning direction relative to an exposure beam during a scanning exposure, and in which a projection system and an optical system are disposed in the path of the exposure beam;    
       
         using the projection system to project a pattern image onto the work 
         - 
         piece, the exposure beam having higher spatial coherence in one direction than in another direction; and  
       
         using the optical system to direct the exposure beam to the work - piece such that said one direction substantially coincides with the scanning direction.    
     
     
       60. A method of manufacturing a device using an object, comprising: 
       
         moving, during a scanning exposure, a mask and the object relative to an exposure beam to expose the object with a pattern formed on the mask;  
       
       
         directing the exposure beam to an irradiation area during the scanning exposure, the mask moving relative to the irradiation area in a scanning direction during the scanning exposure; and  
       
       
         shifting an interference pattern formed in the irradiation area during the scanning exposure.