Enhanced illuminator for use in photolithographic systems

Abstract

Methods and apparatus for enabling both isolated and dense patterns to be accurately patterned onto a wafer are disclosed. According to one aspect of the present invention, an illumination system that is suitable for use as a part of a projection tool includes an illumination source and an illuminator aperture. The illuminator aperture has a center point and an outer edge, and also includes a first pole and a second pole. The first pole is defined substantially about the center point, and the second pole is defined substantially between the first pole and the outer edge of the first pole. The illumination source is arranged to provide a beam to the illuminator aperture.

1. An illumination system, the illumination system being suitable for use as a part of a projection tool, the illumination system comprising:
 an illumination source; and  
 an illuminator aperture, the illuminator aperture having a center point and an outer edge, the illuminator aperture including a first pole that is defined substantially about the center point and a second pole, the second pole being defined substantially between the first pole and the outer edge, the first pole having a first sigma and the second pole having a second sigma, the first sigma being at least aproximately  approximately as large as the second sigma, wherein the illumination source is arranged to provide a beam to the illuminator aperture.  
 
     
     
       2. The illumination system of  claim 1  wherein the first pole has a first area and the second pole has a second area, the second area being substantially equal to the first area. 
     
     
       3. The illumination system of  claim 1  wherein the first pole has a first area and the second pole has a second area, the second area being smaller than the first area. 
     
     
       4. The illumination system of  claim 1  wherein the first pole has a first area and the second pole has a second area, the second area being larger than the first area. 
     
     
       5. The illumination system of  claim 1  wherein the illuminator aperture further includes a third pole, the third pole being defined substantially between the first pole and the outer edge, wherein the second pole has a second area and the third pole has a third area, the third area being substantially equal to the second area. 
     
     
       6. An illumination system, the illumination system being suitable for use as a part of a projection tool, the illumination system comprising:
 an illumination source: and  
 an illuminator aperture, the illuminator aperture having a center point and an outer edge, the illuminator aperture including a first pole that is defined substantially about the center point, a second pole, and a third pole, the second pole being defined substantially between the first pole and the outer edge and the third pole being defined substantially between the first pole and the outer edge, the illumination source being arranged to provide a beam to the illuminator aperture, wherein the first pole has a first area, the second pole has a second area, and the third pole has a third area, the third area being substantially equal to the second area, the first area being substantially equal to a sum of the second area and the third area.  
 
     
     
       7. The illumination system of  claim 1  wherein the second pole has an edge, the edge of the second pole being substantially coincident with the outer edge of the illuminator aperture. 
     
     
       8. The illumination system of  claim 1  wherein the first sigma is approximately the same as the second sigma. 
     
     
       9. The illumination system of  claim 1  wherein (he first sigma is greater than the second sigma. 
     
     
       10. An illuminator aperture, the illuminator aperture being suitable for use as a component of an illumination system that is a part of a projection tool, the illuminator aperture comprising:
 a center pole, the center pole having an associated center pole sigma and being defined about a center point of the illuminator aperture; and  
 a plurality of outer poles, wherein each outer pole of the plurality of outer poles is defined substantially between the center pole and an outer edge of the illuminator aperture, wherein each outer pole of the plurality of outer poles has an outer pole sigma, the center pole sigma being at least aproximately  approximately equal to the outer pole sigma.  
 
     
     
       11. The illuminator aperture of  claim 10  wherein the center pole has a first area and each outer pole of the plurality of outer poles has a second area, the first area being substantially the same as the second area. 
     
     
       12. An illuminator aperture the illuminator aperture being suitable for use as a component of an illumination system that is a part of a projection tool, the illuminator aperture comprising:
 a center pole, the center pole being defined about a center point of the illuminator aperture; and  
 a plurality of outer poles, wherein each outer pole of the plurality of outer poles is defined substantially between the center pole and an outer edge of the illuminator aperture, wherein the center pole has a first area and each outer pole of the plurality of outer poles has a second area, the first area being approximately equal to a sum of the second areas for each pole of the plurality of outer poles.  
 
     
     
       13. The illuminator aperture of  claim 10  wherein each outer pole of the plurality of outer poles has an edge, the edge of each outer pole of the plurality of outer poles being arranged to substantially coincide with the outer edge of the illuminator aperture. 
     
     
       14. The illuminator aperture of  claim 10  wherein the plurality of outer poles includes two outer poles. 
     
     
       15. The illuminator aperture of  claim 10  wherein the plurality of outer poles includes four outer poles. 
     
     
       16. A photolithography apparatus comprising:
 an object;  
 a reticle, the reticle having a plurality of patterns that is arranged to be patterned on the object; and  
 an illuminator, the illuminator including an illumination source and an illuminator aperture, the illumination source being arranged to project a beam through the illuminator aperture to the reticle, wherein the illuminator aperture has a layout that includes an on-axis element and at least one off-axis element, wherein the on-axis element has an associated sigma that is at least approximately equal to an associated sigma of the at least one off-axis element.  
 
     
     
       17. The photolithography apparatus of  claim 16  wherein the plurality of patterns includes isolated patterns and dense patterns, the layout of the illuminator aperture being arranged to accurately pattern the isolated patterns and the dense patterns onto the object. 
     
     
       18. The photolithography apparatus of  claim 16  wherein the at least one off-axis element has a first edge that coincides with an outer edge of the illuminator aperture. 
     
     
       19. The photolithography apparatus of  claim 16  wherein the at least one off-axis element has a first area and the on-axis element has a second area, the first area being approximately equal to the second area. 
     
     
       20. The photolithography apparatus of  claim 16  wherein the at least one off-axis element has a first area and the on-axis element has a second area, the first area being less than the second area. 
     
     
       21. The photolithography apparatus of  claim 16  wherein the at least one off-axis element is an outer pole and the on-axis element is a center pole. 
     
     
       22. A method for using a photolithography apparatus, the photolithography apparatus including an illuminator, a reticle, and an object to be patterned, the method comprising:
 providing a beam from a source associated with the illuminator to an illuminator aperture associated with the illuminator, the illuminator aperture having a small sigma, on-axis element and at least one off-axis element, wherein the at least one off-axis element has an outer edge that is substantially coincident to an outer edge of the illuminator aperture and that is not coincident with an outer edge of the small sigma, on-axis element;  
 passing the beam through the illuminator aperture to the reticle, wherein the reticle includes a dense pattern and an isolated pattern; and  
 patterning the dense pattern and the isolated pattern onto the object.  
 
     
     
       23. The illumination system of  claim 1  wherein the second pole has an outer edge, the outer edge of the second pole being substantially coincident with the outer edge of the illuminator and not coincident with the outer edge of the first pole. 
     
     
       24. An illumination system, the illumination system being suitable for use as a part of a projection tool, the illumination system comprising:
 an illumination source; and  
 an illuminator aperture, the illuminator aperture having a center point and an outer edge, the illuminator aperture including a first pole that is defined substantially about the center point and a second pole, the second pole having a second pole edge and being defined substantially between the first pole and the outer edge, the second pole edge being substantially coincident with the outer pole edge and not coincident with the first pole, wherein the illumination source is arranged to provide a beam to the illuminator aperture.  
 
     
     
       25. An illuminator aperture, the illuminator aperture being suitable for use as a component of an illumination system that is a part of a projection tool, the illuminator aperture comprising;
 a center pole, the center pole having a center pole outer edge and being defined about a center point of the illuminator aperture; and  
 a plurality of outer poles, wherein each outer pole of the plurality of outer poles has an outer pole edge and is defined substantially between the center pole and an outer edge of the illuminator aperture, wherein each outer pole edge is substantially coincident with the outer edge of the illuminator aperture and is not coincident with the center pole outer edge.  
 
     
     
       26. An apparatus comprising:
   a first holding element to hold a patterning element;        a second holding element to hold a substrate;        an illumination source configured to illuminate both dense and sparse features of the patterning element onto the substrate; and        an illuminator optical element positioned between the illumination source and the substrate, the illuminator optical element being configured to control illumination source intensity distribution between the dense features and the sparse features on the patterning element by a first pole having a first sigma and a second pole having a second sigma, the first sigma being at least approximately as large as the second sigma.     
     
     
       27. The apparatus of  claim 26 , wherein the first pole is an on- axis pole for patterning the imaging of the sparse features defined by the patterning element onto the substrate.   
     
     
       28. The apparatus of  claim 27 , wherein the on- axis pole controls the illumination power from the illumination source to be delivered to the patterning element for the imaging of the sparse features onto the substrate.   
     
     
       29. The apparatus of  claim 26 , wherein the second pole is one or more off- axis poles for patterning the imaging of the dense features defined by the patterning element on the substrate respectively.   
     
     
       30. The apparatus of  claim 29 , wherein the one or more off- axis pole controls the illumination power from the illumination source to be delivered to the patterning element for the imaging of the dense features onto the substrate.   
     
     
       31. The apparatus of  claim 26 , wherein the illuminator optical element is a five pole illuminator optical element wherein the first pole is an on- axis pole and the second pole includes four off - axis poles.   
     
     
       32. The apparatus of  claim 31 , wherein the illuminator optical element is configured to control the illumination source intensity between the dense features and the sparse features on the patterning element by providing substantially a same illumination source intensity between the on- axis pole and a sum of the four off - axis poles respectively.   
     
     
       33. The apparatus of  claim 31 , wherein the illuminator optical element is configured to control the illumination source intensity between the dense features and the sparse features on the patterning element by providing more illumination source intensity to the on- axis pole relative to a sum of the illumination intensity provided to the four off - axis poles.   
     
     
       34. The apparatus of  claim 26 , wherein the illuminator optical element is a three- pole illuminator optical element wherein the first pole is an on - axis pole and the second pole includes two off - axis poles.   
     
     
       35. The apparatus of  claim 34 , wherein the illuminator optical element is configured to control the illumination source intensity between the dense features and the sparse features on the patterning element by providing substantially a same illumination source intensity provided to the on- axis pole as provided to the two off - axis poles, respectively.   
     
     
       36. The apparatus of  claim 34 , wherein the illuminator optical element is configured to control the illumination source intensity between the dense features and the sparse features on the patterning element by providing more illumination source intensity to the on- axis pole relative to the illumination intensity provided to the two off - axis poles.   
     
     
       37. The apparatus of  claim 26 , wherein the illuminator optical element includes an on axis layout configured to deliver the illumination source intensity to the sparse features and an off axis layout configured to deliver the illumination source intensity to the dense features respectively. 
     
     
       38. The apparatus of  claim 37 , wherein the on axis layout has an area that is equal to or greater than an area of the sum of the off axis layout. 
     
     
       39. The apparatus of  claim 26 , wherein the illuminator optical element is an illuminator aperture. 
     
     
       40. The apparatus of  claim 26 , wherein the illumination source consists of one of the following types of illumination sources:
   a. g - line illumination source;        b. KrF excimer laser;        c. ArF excimer laser;        d. F 2  type laser; or        e. a charged particle beam illumination source.     
     
     
       41. The apparatus of  claim 26 , wherein the patterning element is a reticle. 
     
     
       42. The apparatus of  claim 26 , further comprising an illuminator, the illuminator including the illumination source, the illuminator optical element, and a condenser lens. 
     
     
       43. The apparatus of  claim 26 , further comprising a lens assembly configured to project the pattern defined by the patterning element and illuminated by the illumination source onto the substrate. 
     
     
       44. The apparatus of  claim 26 , wherein the illuminator optical element is a mask. 
     
     
       45. The apparatus of  claim 26 , wherein the illuminator optical element is an illuminator. 
     
     
       46. The apparatus of  claim 26 , wherein the illuminator optical element controls the illumination source intensity distribution between the dense features and the sparse features on the patterning element by delivering greater than or equal illumination intensity to the sparse features than illumination intensities to the dense features. 
     
     
       47. The apparatus of  claim 26 , wherein the first pole is a small sigma, on axis layout and the second pole is an off axis layout. 
     
     
       48. The apparatus of  claim 26 , wherein the first sigma and the second sigma are characterized such that the intensity distribution being delivered to the first pole characterized by the first sigma is at least equal to the intensity distribution delivered to the second pole characterized by the second sigma. 
     
     
       49. An apparatus comprising:
   an illuminator mask configured to pattern both dense feature geometries and isolated feature geometries of a patterning element by delivering illumination intensity for the sparse feature geometries that is greater than or equal to illumination intensities for the dense feature geometries, wherein the mask has a first pole having a first sigma and a second pole having a second sigma, the first sigma being at least approximately as large as the second sigma.     
     
     
       50. The apparatus of  claim 49 , wherein the mask includes an on axis layout configured to deliver the illumination intensity to the sparse feature geometries and an off axis layout configured to deliver the illumination intensities to the dense feature geometries. 
     
     
       51. The apparatus of  claim 50 , wherein the on axis layout has an area that is equal to or greater than an area of the sum of the off axis layout, the area of the on axis layout configured to deliver the illumination intensity to the sparse feature geometries and a sum of the area of the off axis layout configured to deliver the illumination intensities to the dense feature geometries. 
     
     
       52. The apparatus of  claim 49 , wherein the mask is an optical element. 
     
     
       53. The apparatus of  claim 50 , wherein:
   the on - axis layout is configured to pattern images of the isolated feature geometries, defined by the patterning element, onto a substrate; and        the off - axis layout is configured to pattern images of the dense feature geometries defined by the patterning element on the substrate.     
     
     
       54. The apparatus of  claim 49 , wherein the mask is an illumination aperture having both an on- axis layout and an off - axis layout.   
     
     
       55. The apparatus of  claim 49 , wherein the mask is positioned between an illumination source and the patterning element, the illumination source configured to illuminate the patterning element. 
     
     
       56. The apparatus of  claim 49 , wherein the patterning element is a reticle. 
     
     
       57. The apparatus of  claim 49 , wherein the mask is a single mask. 
     
     
       58. The apparatus of  claim 49 , wherein the mask is a five pole optical element defining one on- axis pole and four off - axis poles.   
     
     
       59. The apparatus of  claim 49 , wherein the mask is a three pole optical element defining one on- axis pole and two off - axis poles.   
     
     
       60. The apparatus of  claim 49 , wherein the illumination source comprises an illumination sources which is one of:
   a. g - line illumination source;        b. KrF excimer laser;        c. ArF excimer laser;        d. F 2  type laser; and        e. a charged particle beam illumination source.     
     
     
       61. The apparatus of  claim 49 , wherein the mask is an optical element configured to control an illumination source intensity between the dense feature geometries and the isolated feature geometries on the patterning element by providing substantially a same illumination source intensity between an on- axis pole and a sum of off - axis poles of the mask.   
     
     
       62. The apparatus of  claim 49 , wherein the mask is an optical element configured to control the illumination source intensity between the dense feature geometries and the isolated feature geometries on the patterning element by providing more illumination source intensity to the on- axis pole relative to a sum of the illumination intensity provided to off - axis poles of the mask.   
     
     
       63. The apparatus of  claim 49 , further comprising a lens assembly configured to project the pattern defined by the patterning element and illuminated by the illumination source onto a substrate. 
     
     
       64. An apparatus comprising an optical element having elements comprising an on axis layout and an off axis layout to control illumination source intensity distribution of both dense and sparse features on a patterning element, the on axis layout being configured to deliver illumination intensity that is greater than or equal to illumination intensities associated with the off axis layout, the optical element including a first pole having a first sigma and a second pole having a second sigma, the first sigma being at least approximately as large as the second sigma. 
     
     
       65. The apparatus of  claim 64 , further comprising:
   the patterning element which defines a pattern having both the dense and sparse features; and        an illumination source configured to illuminate both the dense and sparse features of the patterning element onto a substrate through the optical element, positioned between the patterning element and the illumination source.     
     
     
       66. The apparatus of  claim 65 , wherein the on- axis layout and the off - axis layout controls illumination power from the illumination source to be delivered to the patterning element for the imaging of the sparse features onto the substrate and the dense features onto the substrate, respectively.   
     
     
       67. The apparatus of  claim 65 , wherein the optical element is an illuminator aperture. 
     
     
       68. The apparatus of  claim 65 , wherein the illumination source consists of one of the following types of illumination sources:
   a. g - line illumination source;        b. KrF excimer laser;        c. ArF excimer laser;        d. F 2  type laser; or        e. a charged particle beam illumination source.     
     
     
       69. The apparatus of  claim 64 , wherein the optical element is a mask. 
     
     
       70. The apparatus of  claim 69 , wherein the illumination intensity is at the mask.