Projection optical apparatus

Abstract

A projection optical apparatus for projection an image of an object onto a workpiece, which is suitable for use, for example, as an exposure apparatus used in the manufacture of integrated circuits. The projection optical apparatus includes an image forming optical system whose optical characteristic is changed by the light energy supplied from the illuminated object. A change of the optical characteristic of the optical system is determined by the use of a predetermined parameter whereby when the distribution of the light energy on the pupil of the optical system is changed, the parameter is correct in such a manner that the change of the optical characteristic determined by the parameter is changed in correspondence to the change in the distribution of the light energy.

We claim:  
     
       1. Apparatus for projecting an image of an object along an optical axis onto a workpiece including, in combination, an illumination optical system, an optical lens system and a control system, with said illuminating optical system comprising: 
       light source means for generating a beam of light energy to illuminate said object;  
       shutter means for interrupting said beam of light energy at given time intervals with said interrupted beam reaching full illumination in each time interval over a time constant dependent upon the numerical aperture of said illumination optical system;  
       reticle means containing a pattern representing said object;  
       aperture means having an adjustable aperture;  
       means for adjusting the size of the aperture;  
       means for directing said beam of light energy through said aperture means and upon said reticle means for forming said image;  
       said optical lens system comprising means including a sealed pressurized lens chamber containing a plurality of lenses for projecting light onto said workpiece and having an optical characteristic responsive to an accumulation of heat in said pressurized lens chamber from said light energy, and  
       said control system comprising means responsive to said aperture means for varying the light distribution to said optical lens system in accordance with changes in the numerical aperture of said illuminating optical system;  
       storage means for storing a plurality of time constant  constants or coefficients of change, given as a ratio of the numerical aperture of the illumination optical system to the numerical aperture of the optical lens system, corresponding to a multiplicity of different numerical aperture sizes of said aperture means;  
       selector means responsive to said aperture means for selecting the time constant or coefficient of change from said storage means corresponding to the numerical aperture size of said aperture means; and  
       means for controlling the pressure in said optical lens system corresponding to the selection of said time constant.  
     
     
       2. Apparatus for projecting an image of an object along an optical axis onto a workpiece including, in combination, an illumination optical system, an optical lens system and a control system, with said illuminating optical system comprising: 
       light source means for generating a beam of light energy to illuminate said object;  
       shutter means for interrupting said beam of light energy at given time intervals with said interrupted beam reaching full illumination in each time interval over a time constant dependent upon the numerical aperture of said illumination optical system;  
       reticle means containing a pattern representing said object;  
       aperture means having an adjustable aperture;  
       means for adjusting the size of the aperture;  
       means for directing said beam of light energy through said aperture means and upon said reticle means for forming said image;  
       said optical lens system comprising means including a seated pressurized lens chamber containing a plurality of lenses for projecting light onto said workpiece and having an optical characteristic responsive to an accumulation of heat in said pressurized lens chamber from said light energy, and  
       said control system comprising means responsive to said aperture means for varying the light distribution to said optical lens system in accordance with changes in the numerical aperture of said illuminating optical system,  
       storage means for storing a plurality of time constants or coefficients of change, given as a ratio of the numerical aperture of the illumination optical system to the numerical aperture of the optical lens system, corresponding to a multiplicity of different numerical aperture sizes of said aperture means; and  
       selector means responsive to said aperture means for selecting the time constant or coefficient of change from said storage means corresponding to the numerical aperture size of said aperture means; and  
       means for controlling the light distribution in said optical lens system corresponding to the selection of said time constant.  
     
     
       3. Apparatus for projecting an image of an object along an optical axis onto a workpiece including, in combination, an illumination optical system, an optical lens system and a control system, with said illuminating optical system comprising: 
       light source means for generating a beam of light energy to illuminate said object;  
       shutter means for interrupting said beam of light energy at given time intervals with said interrupted beam reaching full illumination in each time interval over a time constant dependent upon the numerical aperture of said illumination optical system;  
       reticle means containing a pattern representing said object;  
       aperture means having an adjustable aperture;  
       means for adjusting the size of the aperture;  
       means for directing said beam of light energy through said aperture means and upon said reticle means for forming said image;  
       said optical lens system comprising means including a sealed pressurized lens chamber containing a plurality of lenses for projecting light onto said workpiece and having an optical characteristic responsive to an accumulation of heat in said pressurized lens chamber from said light energy, and  
       said control system comprising means responsive to said aperture means for varying the light distribution to said optical lens system in accordance with changes in the numerical aperture of said illuminating optical system,  
       storage means for storing a plurality of time constants or coefficients of change, given as a ratio of the numerical aperture of the illumination optical system to the numerical aperture of the optical lens system, corresponding to a multiplicity of different numerical aperture sizes of said aperture means; and  
       selector means for controlling said aperture means in a relationship corresponding to a selected time constant or coefficient of change in said storage means.  
     
     
       4. Apparatus for projecting an image of an object along an optical axis onto a workpiece including an illumination optical system, an optical lens system and a control system, said illuminating optical system comprising: 
       
         a reticle device containing a pattern representing said object;  
       
       
         an aperture device having an adjustable aperture;  
       
       
         an adjusting device adjusting a size of the aperture;  
       
       
         said optical lens system having a sealed pressurized lens chamber projecting light onto said workpiece and having an optical characteristic responsive to an accumulation of heat in said pressurized lens chamber from said light energy,  
       
       
         a storage device that stores a plurality of time constants or coefficients of change, given as a ratio of a numerical aperture of the illumination optical system to a numerical aperture of the optical lens system, corresponding to a multiplicity of different numerical aperture sizes of said aperture device;  
       
       
         a selector device responsive to said aperture device that selects the time constant or coefficient of change from said storage device corresponding to the numerical aperture size of said aperture device; and  
       
       
         a control device that controls a pressure in said optical lens system corresponding to the selection of said time constant. 
       
     
     
       5. Apparatus for projecting an image of an object along an optical axis onto a workpiece including an illumination optical system, an optical lens system and a control system, said illuminating optical system comprising: 
       
         a reticle device containing a pattern representing said object;  
       
       
         an aperture device having an adjustable aperture;  
       
       
         an adjusting device adjusting a size of the aperture;  
       
       
         said optical lens system having a sealed pressurized lens chamber projecting light onto said workpiece and having an optical characteristic responsive to an accumulation of heat in said pressurized lens chamber from said light energy,  
       
       
         a storage device that stores a plurality of time constants or coefficients of change, given as a ratio of a numerical aperture of the illumination optical system to a numerical aperture of the optical lens system, corresponding to a multiplicity of different numerical aperture sizes of said aperture device; and  
       
       
         a selector device responsive to said aperture device that selects the time constant or coefficient of change from said storage device corresponding to the numerical aperture size of said aperture device; and  
       
       
         a control device that controls a light distribution in said optical lens system corresponding to the selection of said time constant. 
       
     
     
       6. Apparatus for projecting an image of an object along an optical axis onto a workpiece including an illumination optical system, an optical lens system and a control system, said illuminating optical system comprising: 
       
         a reticle device containing a pattern representing said object;  
       
       
         an aperture device having an adjustable aperture;  
       
       
         an adjusting device adjusting a size of the aperture;  
       
       
         said optical lens system having a sealed pressurized lens chamber projecting light onto said workpiece and having an optical characteristic responsive to an accumulation of heat in said pressurized lens chamber from said light energy,  
       
       
         a storage device that stores a plurality of time constants or coefficients of change, given as a ratio of a numerical aperture of the illumination optical system to a numerical aperture of the optical lens system, corresponding to a multiplicity of different numerical aperture sizes of said aperture device; and  
       
       
         a selector device controlling said aperture device in a relationship corresponding to a selected time constant or coefficient of change in said storage device. 
       
     
     
       7. A projection exposure apparatus comprising: 
       
         an illumination optical system that forms a secondary light source, of which a size or a shape is changed, with light from a primary light source to illuminate a pattern with light from the secondary light source;  
       
       
         a projection optical system that projects an image of the pattern on a substrate;  
       
       
         an imaging controller that adjusts an optical property of the projection optical system, using a plurality of constants corresponding to different sizes or shapes of secondary light sources; and  
       
       
         a processor that sets a constant selected in accordance with the changed size or shape of the secondary light source in the imaging controller so that a change in the optical property caused by the change of the size or the shape of the secondary light source is substantially corrected. 
       
     
     
       8. An apparatus according to claim  7 , wherein said imaging controller calculates the change in said optical property by using said selected constant and adjusts said optical property based on the calculated change. 
     
     
       9. A projection exposure apparatus comprising: 
       
         an illumination system that forms a secondary light source, of which a size or shape is changed, with light from a primary light source to illuminate a pattern with light from the secondary light source;  
       
       
         a projection optical system that projects an image of the pattern on a substrate; and  
       
       
         an imaging controller connected with the projection optical system, the imaging controller adjusting an optical property of the projection optical system based on one of a plurality of constants corresponding to different sizes or shapes of secondary light sources, which is selected in accordance with the changed size or shape so as to correct a change in the optical property caused by the change of the size or the shape. 
       
     
     
       10. An apparatus according to claim  9 , wherein said imaging controller includes a device that adjusts pressure in a chamber located between said pattern and said substrate, said light irradiated from said pattern passing through said chamber. 
     
     
       11. An apparatus according to claim  10 , wherein said imaging controller includes a calculator that calculates the change in said optical property by using said selected constant, the calculator controlling said device based on the calculated change. 
     
     
       12. A projection exposure method comprising the steps of: 
       
         changing a size or a shape of a secondary light source formed with light from a primary light source;  
       
       
         determining a constant used in adjusting a change in an optical property of a projection optical system in accordance with the changed size or shape of the secondary light source; and  
       
       
         illuminating a pattern with light from the changed secondary light source so as to expose a substrate with the illuminated pattern through the projection optical system of which the change in the optical property is corrected based on the determined constant. 
       
     
     
       13. A projection exposure method comprising the steps of: 
       
         changing a size or a shape of a secondary light source formed with light from a primary light source; and  
       
       
         adjusting an optical property of a projection optical system based on one of a plurality of constants corresponding to different sizes or shapes of secondary light sources, which is selected in accordance with the changed size or shape of the secondary light source so as to correct a change in the optical property caused by the change of the size or the shape. 
       
     
     
       14. A method according to claim  13 , further comprising: 
       
         illuminating said pattern with light from said changed secondary light source so as to expose a substrate with the illuminated pattern through said projection optical system of which the optical property is corrected. 
       
     
     
       15. A method according to claim  13 , wherein an optical distance between said pattern and said projection optical system is changed to adjust said optical property. 
     
     
       16. A method according to claim  13 , wherein a refractive index in at least one of spaces between said pattern and a substrate exposed with said illuminated pattern is changed to adjust said optical property. 
     
     
       17. A projection exposure method comprising the steps of: 
       
         changing a size or a shape of an illumination source of which an image is substantially formed on a pupil plane of a projection optical system so as to illuminate a pattern with the changed illumination source;  
       
       
         adjusting a distance between the pattern and the projection optical system based on one of a plurality of constants corresponding to different sizes or shapes of illumination sources, which is selected in accordance with the changed size or shape of the illumination source so as to correct a change in an optical property of the projection optical system caused by the change of the size or the shape. 
       
     
     
       18. A semiconductor device manufacturing method comprising the steps of: 
       
         providing a wafer and a device pattern;  
       
       
         changing a size or a shape of an illumination source illuminating the pattern;  
       
       
         adjusting an optical property of a projection optical system based on a constant selected in accordance with the changed size or shape to compensate for a change in the optical property caused by the change of the size or the shape; and  
       
       
         illuminating the pattern with the changed illumination source so as to transfer the illuminated pattern onto the wafer through the adjusted projection optical system. 
       
     
     
       19. A semiconductor device manufacturing apparatus comprising: 
       
         an illumination system that illuminates a device pattern with an illumination source of which a size or a shape is changed;  
       
       
         a projection system that projects an image of the pattern on a wafer and having a pupil plane on which an image of the illumination source is substantially formed; and  
       
       
         an adjusting system that adjusts an optical property of the projection system based on a constant selected in accordance with the changed size or shape of the illumination source to compensate for a change in the optical property caused by the change of the size or the shape. 
       
     
     
       20. A projection exposure method comprising the steps of: 
       
         changing a size or a shape of an illumination light; and  
       
       
         adjusting an optical property of a projection optical system based on one of a plurality of constants corresponding to different sizes or shapes of illumination lights, which is selected in accordance with the changed size or shape of the illumination light so as to correct a change in the optical property caused by the change of the size or the shape. 
       
     
     
       21. A projection exposure apparatus comprising: 
       
         an illumination system that outputs an illumination light, of which a size or shape is changed, to illuminate a pattern;  
       
       
         a projection optical system that projects an image of the pattern on a substrate; and  
       
       
         an imaging controller connected with the projection optical system, the imaging controller adjusting an optical property of the projection optical system based on one of a plurality of constants corresponding to different sizes or shapes of the illumination light, which is selected in accordance with the changed size or shape so as to adjust a change in the optical property caused by the change of the size or the shape. 
       
     
     
       22. A projection exposure apparatus comprising: 
       
         an illumination optical system that illuminates a pattern through an optical integrator, with illumination light from a light source;  
       
       
         a projection optical system that projects the illuminated pattern onto an object;  
       
       
         an optical device disposed on an optical path through which the illumination light passes to change an intensity distribution of the illumination light on a plane, in the illumination optical system, substantially conjugate with a pupil plane of the projection optical system; and  
       
       
         an adjusting system that adjusts the projection optical system so as to correct a change in an optical property of the projection optical system caused by the change of the intensity distribution. 
       
     
     
       23. An apparatus according to claim  22 , wherein 
       
         said optical device includes a stop disposed between said pattern and said optical integrator. 
       
     
     
       24. An apparatus according to claim  22 , wherein 
       
         said optical device includes an optical element disposed between said optical integrator and said light source. 
       
     
     
       25. A projection exposure method comprising: 
       
         changing an intensity distribution of light on a pupil plane of a projection optical system, generated from a pattern by irradiation of illumination light to expose an object with the light through the projection optical system; and  
       
       
         adjusting the projection optical system based on a parameter determined in accordance with the intensity distribution so as to correct a change in an optical property of the projection optical system caused by the change of the intensity distribution. 
       
     
     
       26. A method according to claim  25 , wherein 
       
         a distance between said projection optical system and at least one of said pattern and said object is adjusted. 
       
     
     
       27. A method according to claim  25 , wherein 
       
         said intensity distribution of light is changed by adjusting a distribution of said illumination light on a plane, in an illumination optical system to illuminate said pattern, substantially conjugate with the pupil plane of said projection optical system. 
       
     
     
       28. A method according to claim  25 , wherein 
       
         said intensity distribution of light is changed by adjusting a numerical aperture of said projection optical system. 
       
     
     
       29. A projection exposure method comprising: 
       
         changing an intensity distribution of light on a pupil plane of a projection optical system, said light being generated from a pattern by irradiation of illumination light to expose an object with the light through the projection optical system; and  
       
       
         performing an imaging adjustment in accordance with the change of the intensity distribution in order to form a desired image on the object through the projection optical system. 
       
     
     
       30. A method according to claim  29 , wherein the imaging adjustment compensates for a change of an optical property of the projection optical system that would be caused by the change of the intensity distribution. 
     
     
       31. A method according to claim  29 , wherein the intensity distribution is changeable continuously. 
     
     
       32. A method according to claim  29 , wherein said change of the intensity distribution is performed by using a zoom optical system disposed in an illumination system which directs the illumination light to said pattern. 
     
     
       33. A method according to claim  29 , wherein said change of the intensity distribution is performed by changing an arrangement of optical elements disposed in an illumination system which directs the illumination light to said pattern. 
     
     
       34. A method according to claim  29 , wherein said change of the intensity distribution is performed by expanding said illumination light. 
     
     
       35. A method according to claim  29 , wherein said change of the intensity distribution includes a change of a numerical aperture of the projection optical system. 
     
     
       36. A method according to claim  29 , wherein said change of the intensity distribution includes a change of a distribution of the light from a circular shape to an other shape. 
     
     
       37. A method according to claim  29 , wherein said imaging adjustment includes an adjustment of the projection optical system. 
     
     
       38. A method according to claim  29 , wherein said imaging adjustment includes a movement of a mask on which said pattern is formed. 
     
     
       39. A method according to claim  29 , wherein said imaging adjustment includes a relative movement of the object and an image surface formed through the projection optical system. 
     
     
       40. A projection exposure apparatus comprising: 
       
         an illumination system having a plurality of optical elements that include an optical integrator and that are disposed in a path of illumination light from a light source;  
       
       
         an optical device disposed between the optical integrator and the light source in the illumination system, which changes an intensity distribution of light on a pupil plane of a projection optical system, said light being generated from a pattern by irradiation of the illumination light to expose an object with the light through the projection optical system; and  
       
       
         an adjustment system functionally associated with the optical device, that performs an imaging adjustment in accordance with the change in the intensity distribution in order to form a desired pattern image on the object through the projection optical system. 
       
     
     
       41. An apparatus according to claim  40 , wherein said change of the intensity distribution includes a change of a distribution of the light from a circular shape to an other shape. 
     
     
       42. An apparatus according to claim  40 , wherein said imaging adjustment includes an adjustment of the projection optical system. 
     
     
       43. An apparatus according to claim  40 , wherein said imaging adjustment includes a movement of a mask on which said pattern is formed. 
     
     
       44. An apparatus according to claim  40 , wherein said imaging adjustment includes a relative movement of the object and an image surface formed through the projection optical system. 
     
     
       45. A semiconductor device manufacturing method comprising: 
       
         providing a wafer and a device pattern;  
       
       
         changing an intensity distribution of light on a pupil plane of a projection optical system, the light being generated from the device pattern by irradiation of illumination light to expose the wafer with the light through the projection optical system; and  
       
       
         performing an imaging adjustment in accordance with the change of the intensity distribution in order to form a desired image on the wafer through the projection optical system.