Illumination apparatus, a projection exposure apparatus having the same, a method of manufacturing a device using the same, and a method of manufacturing the projection exposure apparatus

• US 6,049,374 A
• Filed: 03/13/1998
• Issued: 04/11/2000
• Est. Priority Date: 03/14/1997
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Komatsuda, Hideki, Ushida, Kazuo
• Primary Examiner(s): Blankenship, Howard B.
• Assistant Examiner(s): NGUYEN, HUNG
• Application Number:
  US09/042,434
• Time in Patent Office: 760 Days
• Field of Search: 355/53, 355/50, 355/67, 355/71, 355/77, 355/68, 356/399, 356/400, 356/401, 250/548, 250/492.2, 250/49.22, 359/618, 359/798
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70075 Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection
• CPC Class Codes: G03F 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like

Abstract

An illumination apparatus is provided capable of obtaining identical line widths at all positions in an image surface. A projection exposure apparatus using this illumination apparatus is also provided as well as a method of manufacturing the projection exposure apparatus and a method of manufacturing a device using this apparatus. The illumination apparatus includes a light source system for supplying a light beam, an optical integrator for forming a plurality of light sources based on a light beam from the light source and a condenser optical system for converging beams from the plurality of light sources for illuminating an illuminated surface. The apparatus also has a filter placed in a location that is in an optically conjugate relationship to the illuminated surface. The filter has at least a first area corresponding to a first portion of the plurality of light sources, and a second area corresponding to a second portion of the plurality of light sources other than the first portion. The filter has at least one first filter element having a first transmissivity distribution provided over the entirety of the first area of the filter. The filter also has at least one second filter element having a second transmissivity distribution that is the inverse of the first transmissivity distribution provided over the entirety of the second area of the filter.

Claims

1. An illumination apparatus, comprising

a light source system for providing a light beam along a preselected path;

an optical integrator, placed in said path of said light beam to form a plurality of light sources therefrom;

a condenser optical system, placed in the path of light beams that have passed through said plurality of light sources, said condenser optical system guiding light from said optical integrator to an illuminated surface; and

a filter, placed in a location that is in an optically conjugate relationship to said illuminated surface, said filter having at least a first area corresponding to a first portion of said plurality of light sources, and a second area corresponding to a second portion of said plurality of light sources other than said first portion;

wherein,

said filter has at least one first filter element having a first transmissivity distribution provided over the entirety of said first area of said filter; and

has

at least one second filter element having a second transmissivity distribution that is the inverse of said first transmissivity distribution provided over the entirety of said second area of said filter.

2. The illumination apparatus of claim 1, wherein said optical integrator comprises a plurality of lens elements and has an entrance surface end, and said filter is placed at said entrance surface end of said optical integrator.

3. The illumination apparatus of claim 1, further comprising

an auxiliary optical integrator, placed in the light path between said light source system and said optical integrator, for forming a plurality of light sources based on said light beam from said light source system;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary integrator and said optical integrator, for guiding a light beam from said auxiliary integrator to said optical integrator.

4. The illumination apparatus of claim 3, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said illuminated surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources formed by said auxiliary optical integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

has at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

5. The illumination apparatus of claim 1, further comprising

an auxiliary optical integrator, placed in the light path between said condenser optical system and said illuminated surface, for forming a plurality of light sources based on a light beam from said condenser optical system;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary optical integrator and said illuminated surface, for guiding a light beam from said auxiliary optical integrator to said illuminated surface.

6. The illumination apparatus of claim 5, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said illuminated surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources formed by said auxiliary integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

7. The illumination apparatus of claim 1, further comprising an illuminance correction filter, placed in he proximity of said filter, for making the illumination distribution on said illuminated surface uniform.

8. The illumination apparatus of claim 1, wherein said illuminated surface constitutes a plurality of microsurfaces and wherein said first and second filter elements transform the light intensity distribution in the Fourier transform planes of said microsurfaces to a prescribed light intensity distribution, independently for light converging at prescribed points on said illuminated surface, while maintaining the relative illuminance distributed over said illuminated surface.

9. The illumination apparatus of claim 8, further comprising an aperture stop with changeable aperture shape, placed in the light path between said light source system and said illuminated surface, at a location at which said plurality of light sources are formed, or at a location substantially conjugate thereto;

wherein, even when said aperture shape is changed, said first and second filter elements are able to perform their transformation function.

10. A projection exposure apparatus for transferring to a substrate, a prescribed pattern provided on a mask or reticle, said apparatus comprising

an illumination apparatus as recited in claim 1;

a first stage for supporting said mask or reticle;

a projection optical system for projecting said prescribed pattern onto said substrate placed at an image surface, based on light from said illumination apparatus; and

a second stage for supporting said substrate;

wherein said filter having said first and second filter elements is placed in a location that is conjugate to said image surface.

11. The projection exposure apparatus of claim 10, wherein said optical integrator has an entrance surface end and a plurality of lens elements, and said filter is placed at said entrance surface end of said optical integrator.

12. The projection exposure apparatus of claim 10, further comprising

an auxiliary optical integrator, placed in the light path between said light source system and said optical integrator, for forming a plurality of light sources based on said light beam from said light source;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary integrator and said optical integrator, for guiding light beams from said auxiliary integrator to said optical integrator.

13. The projection exposure apparatus of claim 12, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said image surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources formed by said auxiliary optical integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

has at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

14. The projection exposure apparatus of claim 10, further comprising

an auxiliary optical integrator, placed in the light path between said condenser optical system and said first stage, for forming a plurality of light sources based on a light beam from said condenser optical system;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary optical integrator and said first stage, for guiding a light beam from said auxiliary optical integrator to said first stage.

15. The projection exposure apparatus of claim 14, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said image surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources firmed by said auxiliary optical integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

has at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

16. The projection exposure apparatus of claim 10, further comprising an illuminance correction filter, placed in the proximity of said filter, for making the illumination distribution on said image surface uniform.

17. The projection exposure apparatus of claim 10, wherein said illuminated surface constitutes a plurality of microsurfaces and wherein said first and second filter elements transform the light intensity distribution in the Fourier transform planes of said microsurfaces to a prescribed light intensity distribution, independently for light converging at prescribed points on said image surface, while maintaining the relative illuminance distributed over said image surface.

18. The projection exposure apparatus of claim 17, further comprising an aperture stop with changeable aperture shape, placed in the light path between said light source system and said first stage, at a location at which said plurality of light sources are formed, or at a location substantially conjugate thereto;

wherein, even when said aperture shape is changed, said first and second filter elements are able to perform their transformation function.

19. A device manufacturing method comprising the following steps:

a first step of coating a substrate with photosensitive material;

a second step of using the projection exposure apparatus as recited in claim 10 to project the image of said pattern of onto said substrate;

a third step of developing said photosensitive material on said substrate; and

a fourth step of forming a prescribed circuit pattern on said substrate, with said photosensitive material developed in said third step as a mask.

20. An illumination apparatus comprising

a light source system for supplying a light beam;

an optical integrator for forming a plurality of light sources based on said light beam from said light source;

a condenser optical system for converging beams from said plurality of light sources for illuminating an illuminated surface, said illuminated surface constituting a plurality of microsurfaces;

a filter placed in a location that is in an optically conjugate relationship to said illuminated surface, said filter having at least a first area corresponding to a first portion of said plurality of light sources, and a second area corresponding to a second portion of said plurality of light sources other than said first portion;

wherein,

said filter has at least one first filter element having a first transmissivity distribution provided over the entirety of said first area of said filter;

and has at least one second filter element having a second transmissivity distribution provided over the entirety of said second area of said filter; and

said first and second filter elements transform the light intensity distribution in the Fourier transform planes of said microsurfaces to a prescribed light intensity distribution, independently for light converging at prescribed points on said illuminated surface, while maintaining the relative illuminance distributed over said illuminated surface.

21. The illumination apparatus of claim 20, wherein said optical integrator comprises a plurality of lens elements and has an entrance surface end, and said filter is placed at said entrance surface end of said optical integrator.

22. The illumination apparatus of claim 20, further comprising

an auxiliary optical integrator, placed in the light path between said light source system and said optical integrator, for forming a plurality of light sources based on said light beam from said light source system;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary integrator and said optical integrator, for guiding a light beam from said auxiliary integrator to said optical integrator.

23. The illumination apparatus of claim 22, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said illuminated surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources formed by said auxiliary optical integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

has at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

24. The illumination apparatus of claim 20, further comprising

an auxiliary optical integrator, placed in the light path between said condenser optical system and said illuminated surface, for forming a plurality of light sources based on a light beam from said condenser optical system;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary optical integrator and said illuminated surface, for guiding a light beam from said auxiliary optical integrator to said illuminated surface.

25. The illumination apparatus of claim 24, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said illuminated surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources formed by said auxiliary integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

has at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

26. The illumination apparatus of claim 24, further comprising an illuminance correction filter, placed in the proximity of said filter, for making the illumination distribution on said illuminated surface uniform.

27. The illumination apparatus of claim 20, having an aperture stop with changeable aperture shape, placed in the light path between said light source system and said illuminated surface, at a location at which said plurality of light sources are formed, or at a location substantially conjugate thereto;

wherein, even when said aperture shape is changed, said first and second filter elements are able to perform their transformation function.

28. A projection exposure apparatus for transferring to a substrate, a prescribed pattern provided on a mask or reticle, said apparatus comprising

an illumination apparatus as recited in claim 20;

a first stage for supporting said mask or reticle;

a projection optical system for projecting said prescribed pattern onto said substrate placed at an image surface, based on light from said illumination apparatus; and

a second stage for supporting said substrate;

wherein said filter having said first and second filter elements is placed in a location that is conjugate to said image surface, or in the proximity of said location.

29. The projection exposure apparatus of claim 28, wherein said optical integrator has an entrance surface end and a plurality of lens elements, and said filter is placed at said entrance surface end of said optical integrator.

30. The projection exposure apparatus of claim 28, further comprising

an auxiliary optical integrator, placed in the light path between said light source system and said optical integrator, for forming a plurality of light sources based on said light beam from said light source;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary optical integrator and said optical integrator, for guiding light beams from said auxiliary optical integrator to said optical integrator.

31. The projection exposure apparatus of claim 30, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said image surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources formed by said auxiliary optical integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

has at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

32. The projection exposure apparatus of claim 28, further comprising

an auxiliary optical integrator, placed in the light path between said condenser optical system and said first stage, for forming a plurality of light sources based on a light beam from said condenser optical system;

and

an auxiliary condenser optical system, placed in the light path between said auxiliary optical integrator and said first stage, for guiding a light beam from said auxiliary optical integrator to said first stage.

33. The projection exposure apparatus of claim 32, further comprising an auxiliary filter, placed in a location that is in an optically conjugate relationship to said image surface, said auxiliary filter having at least a third area corresponding to a third portion of said plurality of light sources formed by said auxiliary optical integrator and a fourth area corresponding to a fourth portion of said plurality of light sources other than said third portion;

wherein,

said auxiliary filter has at least one third filter element having a third transmissivity distribution provided over the entirety of said third area of said auxiliary filter; and

has at least one fourth filter element having a fourth transmissivity distribution provided over the entirety of said fourth area of said auxiliary filter.

34. The projection exposure apparatus of claim 28, further comprising an illuminance correction filter, placed in the proximity of said filter, for making the illumination distribution on said image surface uniform.

35. The projection exposure apparatus of claim 28, having an aperture stop with changeable aperture shape, placed in the light path between said light source system and said first stage, at a location at which said plurality of light sources are formed, or at a location substantially conjugate thereto;

wherein, even when said aperture shape is changed, said first and second filter elements are able to perform their transformation function.

36. A device manufacturing method comprising the following steps:

a first step of coating a substrate with photosensitive material;

a second step of using the projection exposure apparatus as recited in claim 28 to project the image of said pattern onto said substrate;

a third step of developing said photosensitive material on said substrate; and

a fourth step of forming a prescribed pattern on said substrate, with said photosensitive material developed in said third step as a mask.

37. An illumination apparatus, comprising

a light source system;

an optical integrator, positioned so as to be able to receive a light beam from said light source system, for forming a plurality of light sources based on said light beam;

a condenser optical system, positioned so as to be able to receive light beams that have passed through said plurality of light sources, for converging light beams from said plurality of light sources, for illuminating an illuminated surface;

a first filter, placed in a location that is in an optically conjugate relationship to said illuminated surface, said first filter having a transmissivity distribution such as to transform the light intensity distribution in the Fourier transform planes of microsurfaces constituting said illuminated surface, independently, for light converging at prescribed points on said illuminated surface, to prescribed light intensity distributions; and

a second filter, placed in a location that is in an optically conjugate relationship to said illuminated surface, said second filter having transmissivity distribution for correcting at least nonuniformity of relative illumination distributed over said illuminated surface caused by the transmissivity distribution of said first filter.

38. The illumination apparatus of claim 37, wherein said first filter and said second filter are provided in a single unit.

39. A method of manufacturing a projection exposure apparatus for projecting, onto a substrate, a prescribed pattern formed on a mask or reticle, comprising the following steps:

a first step of guiding a light beam from a light source through

an optical integrator for forming a plurality of light sources based on said light beam,

a condenser optical system for converging light from said optical integrator, for illuminating said mask or reticle,

a projection optical system for forming, on a prescribed image surface, an image of said pattern on said mask or reticle, and onto

an image surface of said projection optical system;

a second step of measuring the relative illuminance distributed on said image surface, and measuring, in the Fourier transform planes of the microsurfaces that constitute said image surface, the light intensity distributions for light converging at at least two points on said image surface;

a third step of placing in a location that is in an optically conjugate relationship to said image surface, a filter having at least a first area corresponding to a first portion of said plurality of light sources, and a second area corresponding to a second portion of said plurality of light sources other than said first portion; and

a fourth step of providing, over the entirety of said first area of said filter, at least one first filter element having a first transmissivity distribution, while also providing, over the entirety of said second area of said filter, at least one second filter element having a second transmissivity distribution;

wherein, in said fourth step, said first and second transmissivity distributions are set so as to maintain said relative illuminations distributed in said image surface substantially uniform, while transforming said light intensity distributions, independently, to prescribed light intensity distributions.

40. A method of manufacturing a projection exposure apparatus for projecting, onto a substrate, a prescribed pattern formed on a mask or reticle, comprising the following steps:

a first step of simulating the guiding of a light beam from a light source through

an optical integrator for forming a plurality of light sources based on said light beam,

a condenser optical system for converging light from said optical integrator, for illuminating said mask or reticle,

a projection optical system for forming, on a prescribed image surface, an image of said pattern on said mask or reticle, and

onto the image surface of said projection optical system;

a second step of computing the relative illuminations distributed in said image surface, and computing the light intensity distribution in the Fourier transform planes of the microsurfaces that constitute said image surface, for light converging at at least two points on said image surface, based on the results obtained in said simulation of said first step;

a third step of setting in a location that is in an optically conjugate relationship to said image surface, a filter having at least a first area corresponding to a first portion of said plurality of light sources, and a second area corresponding to a second portion of said plurality of light sources other than said first portion; and

a fourth step of setting, over the entirety of said first area of said filter, at least one first filter element having a first transmissivity distribution, while also setting, over the entirety of said second area of said filter, at least one second filter element having a second transmissivity distribution;

wherein, in said fourth step, said first and second transmissivity distributions are set so as to maintain said relative illuminations distributed in said image surface substantially uniform, while transforming said light intensity distributions, independently, to prescribed light intensity distributions.