Projection exposure apparatus

Abstract

A projection exposure apparatus includes illuminating optical means for illuminating a projection negative, and projection optical means for projection-exposing the projection negative illuminated by the illuminating optical means onto a substrate, the illuminating optical means including light source means for supplying exposure light, annular light source forming means for forming an annular secondary light source by the light from the light source means, and condenser means for condensing the light beam from the annular light source forming means on the projection negative, and is designed to satisfy the following condition: ⅓≦d 1 /d 2 ≦⅔, where d 1 is the inner diameter of the annular secondary light source, and d 2 is the outer diameter of the annular secondary light source.

1. A projection exposure apparatus including:
 illuminating optical means for illuminating a projection negative; and  
 projection optical means for projection-exposing said projection negative illuminated by said illuminating optical means onto a substrate;  
 said illuminating optical means including light source means for supplying exposure light, annular light source forming means for forming an annular secondary light source, which has a plurality of light source images, by the light from said light source means, and condenser means for condensing light from said annular light source forming means on said projection negative;  
 said apparatus satisfying the following condition: 
   ⅓≦d 1 /d 2 ≦⅔,  
 
 where d 1  is the inner diameter of said annular secondary light source, and d 2  is the outer diameter of said annular secondary light source;  
 said apparatus also satisfying the following condition: 
   0.45≦NA 2 /NA 1 ≦0.8,  
 
 
       where NA 1  is the numerical aperture of said projection optical means, and NA 2  is the numerical aperture of said illuminating optical means determined by the outer diameter of said annular secondary light source. 
     
     
       2. A projection exposure apparatus according to  claim 1 , wherein said annular light source forming means includes:
 an optical integrator; and  
 stop means disposed in the optical path of light emerging from said optical integrator and having an annular opening portion.  
 
     
     
       3. A projection exposure apparatus according to  claim 2 , wherein said optical integrator is comprised of a plurality of lens elements. 
     
     
       4. A projection exposure apparatus according to  claim 2 , wherein said optical integrator includes a bar-like optical element. 
     
     
       5. A projection exposure apparatus according to  claim 2 , wherein said stop means has a plurality of opening portions differing in the ratio of the inner diameter of said annular opening portion to the outer diameter of said annular opening portion from one another, and one of said plurality of opening portions of said stop means is disposed in said optical path. 
     
     
       6. A projection exposure apparatus according to  claim 5 , wherein said stop means includes a circular opening portion. 
     
     
       7. A projection exposure apparatus according to  claim 5 , further including:
 driving means for disposing one of said plurality of opening portions in said optical path;  
 input means for inputting information regarding various conditions during exposure; and  
 control means for controlling said driving means on the basis of the input information from said input means.  
 
     
     
       8. A projection exposure apparatus according to  claim 7 , wherein said input means includes detecting means for detecting a mark on said projection negative on which the information regarding the various conditions during exposure is recorded. 
     
     
       9. A projection exposure apparatus according to  claim 1 , wherein said projection optical means includes an aperture stop of which the diameter of the opening is variable, and said projection exposure apparatus further includes:
 driving means for varying said diameter of the opening of said aperture stop;  
 input means for inputting information regarding various conditions during exposure; and  
 control means for controlling said driving means on the basis of the input information from said input means.  
 
     
     
       10. A projection exposure apparatus according to  claim 1 , wherein said annular light source forming means includes light guide means for transmitting said exposure light. 
     
     
       11. A projection exposure apparatus according to  claim 10 , wherein said light guide means is constructed such that the entrance side cross-sectional shape of said light guide means is circular and the exit side cross-sectional shape of said light guide means is annular. 
     
     
       12. A projection exposure apparatus including:
 illumination optical means for illuminating a projection negative; and  
 projection optical means for projection-exposing said projection negative illuminated by said illumination optical means onto a substrate;  
 said illumination optical means including light source means for supplying exposure light, means for forming a secondary light source, which has a plurality of light source images, by the light from said light source means, means including annular ratio changing means for converting said secondary light source into an annular secondary light source and changing a ratio between an inner diameter and outer diameter of said annular secondary light source, and condenser means for condensing light from said annular secondary light source onto said projection negative,  
 said apparatus satisfying the following condition: 
   ⅓≦d 1 /d 2 ≦⅔ 
 
 where d 1  is the inner diameter of said annular secondary light source, and d 2  is the outer diameter of said annular secondary light source, and said apparatus satisfying the following condition: 
   0.45≦NA 2 /NA 1 ≦0.8  
 
 where NA 1  is the numerical aperture of said projection optical means, and NA 2  is the numerical aperture of said illumination optical means determined by the outer diameter of said annular secondary light source.  
 
     
     
       13. A projection exposure apparatus according to  claim 12 , wherein said means for forming said secondary light source has an optical integrator. 
     
     
       14. A projection exposure apparatus according to  claim 13 , wherein said annular ratio changing means includes stop means disposed in an optical path of light flux emergent from said optical integrator and having an annular opening portion. 
     
     
       15. A projection exposure apparatus according to  claim 14 , wherein said stop means includes a plurality of opening portions differing from one another in a ratio of inner diameter of said annular opening portion to outer diameter of said annular opening portion, and one of said plurality of opening portions of said stop means is disposed in the optical path of said illumination optical means. 
     
     
       16. A projection exposure apparatus according to  claim 15 , wherein said stop means includes a circular opening portion. 
     
     
       17. A projection exposure apparatus according to  claim 15 , further including:
 driving means for disposing one of said plurality of opening portions in said optical path;  
 input means for inputting information regarding various conditions during exposure; and  
 control means for controlling said driving means on the basis of the input information from said input means.  
 
     
     
       18. A projection exposure apparatus according to  claim 12 , further including:
 input means for inputting information regarding various conditions during exposure; and  
 control means for controlling said annular ratio changing means on the basis of the input information from said input means.  
 
     
     
       19. A projection exposure apparatus according to  claim 18 , wherein said annular ratio changing means includes a plurality of opening portions of which a ratio between an inner diameter and an outer diameter is different from one another, and one of said plurality of opening portions is disposed in an optical path of said illumination optical means. 
     
     
       20. A projection exposure apparatus according to  claim 18 , wherein said annular ratio changing means is disposed in an optical path of said illumination optical means and includes a movable stop for changing the ratio between the inner diameter and outer diameter. 
     
     
       21. A projection exposure apparatus comprising: an illuminating optical system; and
 a projection optical system;  
 said illumination optical system including a light source, an optical integrator and a condenser optical system;  
 light from said light source passing through said optical integrator, said condenser optical system, a projection negative and said projection optical system, and onto a substrate;  
 said optical integrator forming a plurality of annular light source images; and  
 the following conditions being satisfied: 
   ⅓≦d 1 /d 2 ≦⅔ 
   0.45≦NA 2 /NA 1 ≦0.8  
 
 where d 1  is an inner diameter of said plurality of annular light source images, d 2  is an outer diameter of said plurality of annular light source images, NA 1  is the numerical aperture of said projection optical system at a side of said projection negative and NA 2  is the numerical aperture of said condenser optical system at an exit side determined by the outer diameter of said plurality of annular light source images.  
 
     
     
       22. A projection exposure apparatus including:
 an illumination optical system; and  
 a projection optical system;  
 said illumination optical system including a light source, an optical integrator, an annular stop and a condenser optical system;  
 light from said light source passing through said optical integrator, said condenser optical system, a projection negative and said projection optical system and onto a substrate;  
 said annular stop being provided at a position where a plurality of images are formed by said illumination optical system;  
 said apparatus satisfying the following conditions: 
   ⅓≦d 1 /d 2 ≦⅔ 
   0.45≦NA 2 /NA 1 ≦0.8  
 
 where d 1  is an inner diameter of an opening of said annular stop, d 2  is an outer diameter of the opening of said annular stop, NA 1  is the numerical aperture of said projection optical system at a side of said projection negative and NA 2  is the numerical aperture of said condenser optical system at an exit side determined by the outer diameter of the opening of said annular stop.  
 
     
     
       23. A projection exposure apparatus comprising:
 an illuminating optical system; and  
 a projection optical system;  
 said illuminating optical system including a light source, an optical integrator, an annular stop and a condenser optical system;  
 light from said light source passing through said optical integrator, said condenser optical system, a projection negative and said projection optical system and onto a substrate;  
 said illuminating optical system forming a plurality of annular light source images satisfying the following condition: 
   ⅓≦d 1 /d 2 ≦⅔ 
 
 where d 1  is an inner diameter of said plurality of annular light source images and d 2  is an outer diameter of said plurality of annular light source images; and  
 said projection exposure apparatus satisfying the following condition: 
   0.45≦NA 2 /NA 1 ≦0.8,  
 
 where NA 1  is the numerical aperture of said projection optical system at a side of said projection negative, and NA 2  is the numerical aperture of said condenser optical system at an exit side determined by an outer diameter of an opening of said annular stop.  
 
     
     
       24. A projection exposure apparatus comprising:
 an illuminating optical system; and  
 a projection optical system;  
 said illuminating optical system including a light source, an optical integrator and a condenser optical system;  
 light from said light source passing through said optical integrator, said condenser optical system, a projection negative and said projection optical system and onto a substrate;  
 said illuminating optical system forming a plurality of annular light source images satisfying the following condition: 
   ⅓≦d 1 /d 2 ≦⅔,  
 
 where d 1  is an inner diameter of said plurality of annular light source images, d 2  is an outer diameter of said plurality of annular light source images;  
 the ratio between the inner diameter and the outer diameter of said annular light source images being variable within the range of said condition;  
 said projection exposure apparatus satisfying the following condition: 
   0.45≦NA 2 /NA 1 ≦0.8,  
 
 where NA 1  is the numerical aperture of said projection optical system at a side of said projection negative, and NA 2  is the numerical aperture of said condenser optical system at an exit side determined by the outer diameter of said plurality of annular light source images.  
 
     
     
       25. A projection exposure apparatus comprising:
 an illuminating optical system; and  
 a projection optical system;  
 said illuminating optical system including a light source, an optical integrator, a first annular stop, a second annular stop and a condenser optical system;  
 light from said light source passing through said optical integrator, said condenser optical system, a projection negative and said projection optical system and onto a substrate;  
 said first and second annular stops satisfying the following condition: 
   ⅓≦d 1 /d 2 ≦⅔,  
 
 where d 1  is an inner diameter of an opening of said annular stops and d 2  is an outer diameter of an opening of said annular stops;  
 said first and second annular stops being selectively disposed in a position where a plurality of light source images are formed by said illuminating optical system; and  
 said projection exposure apparatus satisfying the following condition: 
   0.45≦NA 2 /NA 1 ≦0.8,  
 
 where NA 1  is the numerical aperture of said projection optical system at a side of said projection negative, and NA 2  is the numerical aperture of said condenser optical system at an exit side determined by the outer diameter of said plurality of annular light source images.  
 
     
     
       26. A projection exposure apparatus comprising:
   an illumination optical system in which an optical system is disposed on an optical path to form an annular secondary light source with light emitted by a first light source, said optical system changing an annular ratio of an inner diameter to an outer diameter with respect to the annular secondary light source; and        a projection optical system disposed in an optical path between the mask and a substrate so as to project an image of the mask onto the substrate;        said illumination optical system satisfying the following condition:          1 / 3 ≦d   1   /d   2   ≦  2 / 3           wherein d   1    is the inner diameter of the annular secondary light source and d   2    is the outer diameter of the annular secondary light source.     
     
     
       27. An apparatus according to  claim 26 , wherein said optical system includes an optical integrator and an optical element having a conical surface, disposed between said first light source and the optical integrator. 
     
     
       28. An apparatus according to  claim 27 , wherein said optical integrator includes a fly- eye type integrator or an internal reflection type integrator.   
     
     
       29. An apparatus according to  claim 26 , wherein said optical system satisfies the following condition:
       0 . 45 ≦NA   2   /NA   1   ≦ 0 . 8         wherein NA   1    is the numerical aperture of said projection optical system, and NA   2    is the numerical aperture of said illumination optical system determined by the outer diameter of said annular secondary light source.     
     
     
       30. An apparatus according to  claim 26 , wherein said optical system comprises a plurality of annular stops having annular ratios that are different from each other so as to set one of said plurality of annular stops in an optical path selectively. 
     
     
       31. An apparatus according to  claim 26 , wherein said optical system comprises a first optical element with a first conical surface, a second optical element with a second conical surface and a variable distance between said first optical element and said second optical element so as to change an annular ratio with respect to the annular secondary light source. 
     
     
       32. An apparatus according to  claim 31 , wherein said optical system further comprises an optical integrator disposed in an optical path between said second optical element and the mask. 
     
     
       33. A projection exposure apparatus comprising:
   an illumination optical system disposed on an optical path of light emitted by a light source so as to illuminate a mask, the illumination optical system including an optical system disposed in an optical path between the light source and the mask so as to form a variable annular illumination source, said optical system changing an annular ratio of the variable annular illumination source; and        a projection optical system disposed in an optical path between the mask and a substrate so as to project an image of the mask onto the substrate;        said projection exposure apparatus satisfying the following condition:          0 . 45 ≦NA   2   /NA   1   ≦ 0 . 8           wherein NA   1    is the numerical aperture of said projection optical system, and NA   2    is the numerical aperture of said illumination optical system determined by the outer diameter of said variable annular illumination source.     
     
     
       34. An apparatus according to  claim 33 , wherein said illumination optical system includes an optical integrator and a stop disposed adjacent to the optical integrator to form said annular illumination source. 
     
     
       35. An apparatus according to  claim 33 , wherein said optical system changes the annular ratio of said annular illumination source in accordance with a pattern on said mask. 
     
     
       36. An apparatus according to  claim 35 , wherein said optical system includes a plurality of annular stops having annular ratios that are different from each other, one of the plurality of annular stops selected in accordance with said pattern being disposed on said optical path. 
     
     
       37. An apparatus according to  claim 33 , wherein said optical system comprises a first optical element with a first conical surface, a second optical element with a second conical surface and a variable distance between said first optical element and said second optical element so as to change an annular ratio with respect to the variable annular illumination source. 
     
     
       38. An apparatus according to  claim 37 , wherein said optical system further comprises an optical integrator disposed in an optical path between said second optical element and the mask. 
     
     
       39. A projection exposure apparatus comprising:
   an illumination optical system disposed in an optical path of light emitted by a light source so as to illuminate a mask, the illumination optical system including an optical system disposed in an optical path between the light source and the mask so as to form an annular illumination source, said optical system changing an annular ratio of the annular illumination source in accordance with a pattern formed on the mask; and        a projection optical system disposed in an optical path between the mask and a substrate so as to project an image of the mask onto the substrate, said projection optical system including a pupil defining unit disposed within the projection optical system so as to define a pupil of the projection optical system;        wherein the pupil defining unit comprises a variable aperture stop.     
     
     
       40. An apparatus according to  claim 39 , wherein said projection optical system has a numerical aperture not less than  0 . 4  at a side of the substrate. 
     
     
       41. An apparatus according to  claim 39 , wherein said illumination optical system satisfies the following condition:
       1 / 3 ≦d   1   /d   2        wherein d   1    is the inner diameter of the annular secondary light source and d   2    is the outer diameter of the annular secondary light source.     
     
     
       42. An apparatus according to  claim 41 , wherein said projection exposure apparatus satisfies the following condition:
       0 . 45 ≦NA   2   /NA   1        wherein NA   1    is a numerical aperture of said projection optical system, and NA   2    is a numerical aperture of said illumination optical system determined by the outer diameter of said variable annular illumination source.     
     
     
       43. An apparatus according to  claim 41 , wherein said optical system comprises an optical integrator and an aperture stop unit disposed in an optical path between said optical integrator and the mask, the aperture stop unit includes a circular opening and an annular opening so as to selectively form one of a circular illumination source and the annular illumination source. 
     
     
       44. An apparatus according to  claim 41 , wherein said optical system changes the annular ratio with respect to the annular illumination source under a high illumination efficiency. 
     
     
       45. An apparatus according to  claim 44 , wherein said optical system comprises a first optical element with a first conical surface that is disposed in an optical path between the light source and the mask, a second optical element with a second conical surface that is disposed in the optical path between said first optical element and the mask, and a variable distance between said first optical element and said second optical element so as to change an annular ratio with respect to the annular illumination source. 
     
     
       46. An apparatus according to  claim 45 , wherein said optical system further comprises an optical integrator disposed in an optical path between said second optical element and the mask. 
     
     
       47. A projection exposure apparatus comprising:
   an illumination optical system disposed in an optical path between a light source and a mask so as to illuminate the mask;        a projection optical system disposed in an optical path between the mask and a substrate so as to project an image of the mask onto the substrate; and        an optical system disposed within the illumination optical system so as to form one of a circular secondary light source and an annular secondary light source selectively based on light from the light source, the optical system changing a size of the circular secondary light source and changing an annular ratio of the annular secondary light source.     
     
     
       48. An apparatus according to  claim 47 , wherein said projection exposure apparatus satisfies the following condition:
       0 . 45 ≦NA   2   /NA   1        wherein NA   1    is a numerical aperture of said projection optical system, and NA   2    is a numerical aperture of said illumination optical system determined by the outer diameter of said variable annular illumination source.     
     
     
       49. An apparatus according to  claim 48 , wherein said optical system comprises an optical integrator and an aperture stop disposed in an optical path between the optical integrator and the mask, the aperture stop unit includes a circular opening and an annular opening so as to selectively form one of the circular secondary light source and the annular secondary light source. 
     
     
       50. An apparatus according to  claim 48 , wherein said optical system comprises a first optical element with a first conical surface that is disposed in an optical path between the light source and the mask, a second optical element with a second conical surface that is disposed in the optical path between said first optical element and the mask, and a variable distance between said first optical element and said second optical element so as to change the annular ratio with respect to the annular secondary light source. 
     
     
       51. An apparatus according to  claim 50 , wherein said illumination optical system satisfies the following condition:
       1 / 3 ≦d   1   /d   2        wherein d   1    is the inner diameter of the annular secondary light source and d   2    is the outer diameter of the annular secondary light source.     
     
     
       52. An apparatus according to  claim 48 , wherein said illumination optical system satisfies the following condition:
       1 / 3 ≦d   1   /d   2        wherein d   1    is the inner diameter of the annular secondary light source and d   2    is the outer diameter of the annular secondary light source.     
     
     
       53. A projection exposure apparatus comprising:
   an illumination optical system in which an internal reflection type integrator is disposed on an optical axis to illuminate a mask with light from a light source passing through the internal reflection type integrator; and        a projection optical system, disposed in an optical path between the mask and a substrate, through which light from the mask passes, the projection optical system including a pupil defining unit disposed within the projection optical system so as to define a pupil of the projection optical system;        said illumination optical system including an optical device disposed on the optical axis to form a light intensity distribution having a substantially annular shape on a pupil plane of the illumination optical system, the optical device being capable of changing at least one of the annular ratio, the outer diameter, and the inner diameter of the light intensity distribution in accordance with a pattern on the mask.     
     
     
       54. An apparatus according to  claim 53 , wherein said optical device comprises a plurality of annular stops having annular ratios that are different from each other so as to set one of said plurality of annular stops in an optical path selectively. 
     
     
       55. An apparatus according to  claim 53 , wherein said optical device changes the annular ratio with respect to the light intensity distribution under a high illumination efficiency. 
     
     
       56. An apparatus according to  claim 55 , wherein said optical device comprises a first optical element with a first conical surface, a second optical element with a second conical surface and a variable distance between said first optical element and said second optical element so as to change the annular ratio. 
     
     
       57. An apparatus according to  claim 56 , wherein said optical device further comprises an optical integrator disposed between said second optical element and the mask. 
     
     
       58. An apparatus according to  claim 53 , wherein said illumination optical system satisfies the following condition:
       1 / 3 ≦d   1   /d   2        wherein d   1    is the inner diameter of the annular secondary light source and d   2    is the outer diameter of the annular secondary light source.     
     
     
       59. An apparatus according to  claim 58 , wherein said projection exposure apparatus satisfies the following condition:
       0 . 45 ≦NA   2   /NA   1        wherein NA   1    is a numerical aperture of said projection optical system, and NA   2    is a numerical aperture of said illumination optical system determined by the outer diameter of said variable annular illumination source.     
     
     
       60. An apparatus according to  claim 58 , wherein said optical device comprises a first optical element with a first conical surface, a second optical element with a second conical surface and a variable distance between said first optical element and said second optical element so as to change the annular ratio. 
     
     
       61. An apparatus according to  claim 60 , wherein said projection exposure apparatus satisfies the following condition:
       0 . 45 ≦NA   2   /NA   1        wherein NA   1    is a numerical aperture of said projection optical system, and NA   2    is a numerical aperture of said illumination optical system determined by the outer diameter of said variable annular illumination source.     
     
     
       62. A projection exposure apparatus comprising:
   an illumination optical system that illuminates a mask and comprising a light source including an excimer laser, and an optical system disposed in an optical path formed by the light source so as to form an annular secondary light source having a light intensity distribution with a substantially annular shape on a pupil of the illumination optical system and an deflection member disposed in an optical path between said light source and said optical system; and        a projection optical system disposed in an optical path between the mask and a substrate so as to project an image of the mask onto the substrate;        wherein said optical system changes an annular ratio with respect to the light intensity distribution.     
     
     
       63. An apparatus according to  claim 62 , wherein said projection exposure apparatus satisfies the following condition:
       0 . 45 ≦NA   2   /NA   1        wherein NA   1    is a numerical aperture of said projection optical system, and NA   2    is a numerical aperture of said illumination optical system determined by the outer diameter of said variable annular illumination source.     
     
     
       64. An apparatus according to  claim 63 , further comprising:
   an optical integrator disposed in an optical path between said optical system and the mask, said optical integrator including a fly - eye type integrator or an internal reflection type integrator.     
     
     
       65. An apparatus according to  claim 63 , further comprising a pupil changing unit disposed within said projection optical system so as to define a pupil of said projection optical system and change a numerical aperture of said projection optical system. 
     
     
       66. An apparatus according to  claim 62 , wherein said optical system includes a first optical element with a first conical surface that is disposed in an optical path between the light source and the mask, a second optical element with a second conical surface that is disposed in the optical path between said first optical element and the mask, and a variable distance between said first optical element and said second optical element so as to change the annular ratio with respect to the light intensity distribution. 
     
     
       67. An apparatus according to  claim 66 , further comprising a pupil changing unit disposed within said projection optical system so as to define a pupil of said projection optical system and change a numerical aperture of said projection optical system. 
     
     
       68. An apparatus according to  claim 66 , wherein said optical system further comprises an optical integrator disposed in an optical path between said second optical element and the mask. 
     
     
       69. An apparatus according to  claim 62 , wherein said illumination optical system satisfies the following condition:
       1 / 3 ≦d   1   /d   2   ≦  2 / 3         where d   1    is the inner diameter of the annular secondary light source and d   2    is the outer diameter of the annular secondary light source.     
     
     
       70. An apparatus according to  claim 62 , wherein said optical system changes the annular ratio with respect to the annular secondary light source under a high illumination efficiency. 
     
     
       71. An apparatus according to  claim 70 , wherein said optical system includes a first optical element with a first conical surface that is disposed in an optical path between the light source and the mask, a second optical element with a second conical surface that is disposed in the optical path between said first optical element and the mask, and a variable distance between said first optical element and said second optical element so as to change the annular ratio with respect to the light intensity distribution. 
     
     
       72. An apparatus according to  claim 71 , wherein said optical system further comprises an optical integrator disposed in an optical path between said second optical element and the mask. 
     
     
       73. An apparatus according to  claim 65 , wherein said pupil defining unit comprises an aperture stop unit changing the pupil of said projection optical system. 
     
     
       74. An apparatus according to  claim 73 , wherein said aperture stop unit comprises a variable aperture stop. 
     
     
       75. A projection exposure apparatus comprising:
   an illumination optical system disposed in an optical path of light emitted by a light source so as to illuminate a mask, said illumination optical system including an optical system disposed in an optical path between the light source and the mask so as to form a variable annular illumination source, said optical system changing an annular ratio with respect to the annular illumination source; and        a projection optical system disposed in an optical path between the mask and a substrate so as to project an image of the mask onto the substrate, said projection optical system including a pupil defining unit disposed within said projection optical system so as to define a pupil of said projection optical system;        said projection exposure apparatus satisfying the following condition:          0 . 45 ≦NA   2   /NA   1          wherein NA   1    is a numerical aperture of said projection optical system, and NA   2    is a numerical aperture of said illumination optical system determined by the outer diameter of said variable annular illumination source.     
     
     
       76. An apparatus according to  claim 75 , wherein said optical system changes the annular ratio with respect to the annular illumination source under a high illumination efficiency. 
     
     
       77. An apparatus according to  claim 76 , wherein said optical system comprises a first optical element with a first conical surface that is disposed in an optical path between the light source and the mask, a second optical element with a second conical surface that is disposed in the optical path between said first optical element and the mask, and a variable distance between said first optical element and said second optical element so as to change the annular ratio with respect to the annular illumination source. 
     
     
       78. An apparatus according to  claim 77 , wherein said optical system further comprises an optical integrator disposed in an optical path between said second optical element and the mask. 
     
     
       79. An apparatus according to  claim 76 , wherein said pupil defining unit comprises an aperture stop unit changing the pupil of said projection optical system. 
     
     
       80. An apparatus according to  claim 79 , wherein said aperture stop unit comprises a variable aperture stop. 
     
     
       81. An apparatus according to  claim 76 , wherein said projection optical system has a numerical aperture not less than  0 . 4  at a side of the substrate. 
     
     
       82. An apparatus according to  claim 75 , wherein said illumination optical system satisfies the following condition:
       1 / 3 ≦d   1   /d   2        wherein d   1    is the inner diameter of the annular secondary light source and d   2    is the outer diameter of the annular secondary light source.