Projection exposure apparatus and method employing rectilinear aperture stops for use with periodic mask patterns

• US 6,661,498 B1
• Filed: 04/10/2000
• Issued: 12/09/2003
• Est. Priority Date: 02/10/1995
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Hirukawa, Shigeru
• Primary Examiner(s): Braun, Fred L.
• Application Number:
  US09/546,233
• Time in Patent Office: 1,338 Days
• Field of Search: 355/30, 355/52, 355/53, 355/71, 355/77
• US Class Current: 355/71
• CPC Class Codes: G03B 27/42 for automatic sequential copying of the same original G03B27/34, G03B27/53 take precedence
• CPC Class Codes: G03F 7/70066 Size and form of the illuminated area in the mask plane, e.g. reticle masking blades or blinds
• CPC Class Codes: G03F 7/7025 Size or form of projection system aperture, e.g. aperture stops, diaphragms or pupil obscuration; Control thereof
• CPC Class Codes: G03F 7/70308 Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift
• CPC Class Codes: G03F 7/70425 Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning

Abstract

A projection optical system and method projects and forms an image of a pattern arrayed on a first surface (mask), and exhibiting a periodicity in a predetermined direction (X- or Y-direction), on a second surface (wafer). A stop has an aperture showing a line symmetry with respect to a symmetric axis intersecting an optical axis of the projection optical system and extending in a direction (Y- or X-direction) orthogonal to the predetermined direction and having the outline at least a part of which are rectilinear portions. The stop is disposed on a Fourier transform plane of the first surface within the projection optical system or a surface in the vicinity thereof.

Claims

1. A projection optical system for projecting and forming an image of a pattern arrayed on a first surface, and exhibiting a periodicity in a predetermined direction, on a second surface,

said projection optical system comprising a stop having an aperture showing a line symmetry with respect to a symmetric axis passing through an optical axis of said projection optical system and extending in a direction orthogonal to said predetermined direction and having an outline at least a part of which is rectilinear, said stop being provided on a Fourier transform plane of the first surface within said projection optical system or a plane in the vicinity thereof, said stop limiting, with said aperture having said rectilinear part, an area through which diffracted light generated with said pattern passes.

2. The projection optical system according to claim 1, wherein the outline of said aperture of the stop has a rectilinear portion parallel to the symmetric axis.

3. The projection optical system according to claim 1, wherein said stop has a plurality of movable blades with rectilinear edges each for defining the outline of the aperture.

4. The projection optical system according to claim 3, wherein said movable blades have a first blade set consisting of four blades moved interlocking with each other to define a substantially rectangular aperture with a variable size and a second blade set consisting of four blades moved interlocking with each other to define the substantially rectangular aperture with the variable size and making an angle of 45 degrees to each of said blades of said first blade set.

5. The projection optical system according to claim 1, wherein said stop has a fixed stop formed with a circular aperture and a variable stop formed with a rectangular aperture with a variable size.

6. A projection exposure apparatus comprising:

a projection optical system for projecting and forming an image of a pattern arrayed on a first surface, and exhibiting a periodicity in a predetermined direction, onto a second surface;

a stop having an aperture provided on a Fourier transform plane of the first surface within said projection optical system or a plane in the vicinity thereof and showing a line symmetry with respect to a symmetric axis passing through an optical axis of said projection optical system and extending in a direction orthogonal to said predetermined direction and having an outline at least a part of which is rectilinear, said stop limiting, with said aperture having said rectilinear part, an area through which diffracted light generated with said pattern passes; and

an illumination optical system for Kö

hler-illuminating said first surface with beams of exposure illumination light that are emitted from a surface light source having an outline corresponding to a rectilinear portion of the outline of the aperture of said stop that has a rectilinear shape,

wherein a mask formed with a pattern to be transferred is set on the first surface, a photosensitive substrate is set on the second surface, and the pattern on said mask is exposed onto said photosensitive substrate through said projection optical system with the light beams from said illumination optical system.

7. The projection exposure apparatus according to claim 6, wherein said surface light source of said illumination optical system is of a rectangular frame-like configuration.

8. The projection exposure apparatus according to claim 6, wherein the outline of said stop has a rectilinear portion parallel to the symmetric axis.

9. The projection exposure apparatus according to claim 6, wherein said stop has a plurality of movable blades with rectilinear edges each for defining the outline of the aperture.

10. The projection exposure apparatus according to claim 9, wherein said movable blades have a first blade set consisting of four blades moved interlocking with each other to define a substantially rectangular aperture with a variable size and a second blade set consisting of four blades moved interlocking with each other to define the substantially rectangular aperture with the variable size and making an angle of 45 degrees to each of said blades of said first blade set.

11. The projection exposure apparatus according to claim 6, wherein said stop has a fixed stop formed with a circular aperture and a variable stop formed with a rectangular aperture with a variable size.

12. A projection optical system for projecting an image of a pattern arrayed on a first surface, and exhibiting a periodicity in a predetermined direction, onto a second surface, said projection optical system comprising:

an aperture stop disposed on or in the vicinity of a pupil plane of said projection optical system and having an edge extending in a direction orthogonal to the predetermined direction so as to shield a part of diffracted light generated with said pattern.

13. A projection exposure apparatus for transferring a pattern formed on a mask, and periodically arrayed in a predetermined direction, onto a photosensitive substrate through a projection optical system, said projection exposure apparatus comprising:

an aperture stop disposed within or in the vicinity of a pupil plane of said projection optical system and having an edge extending in a direction orthogonal to the predetermined direction so as to shield a part of diffracted light generated with said pattern.

14. The projection exposure apparatus according to claim 13, wherein at least one of a configuration and a size of said aperture stop is variable.

15. A projection exposure apparatus according to claim 13, further comprising:

an illumination optical system that illuminates said mask; and

a stop disposed within or in the vicinity of a pupil plane of said illumination optical system, that rectilinearly defines a portion of an outline of a light source image formed thereat.

16. A projection exposure apparatus according to claim 15, wherein said stop disposed within or in the vicinity of a pupil plane of said illumination optical system defines said image of the light source in a rectangular frame-like shape.

17. A projection exposure apparatus according to claim 15, wherein a shape of said aperture stop disposed within or in the vicinity of the pupil plane of said projection optical system corresponds to a shape of said stop disposed within or in the vicinity of the pupil plane of said illumination optical system.

18. An exposure apparatus according to claim 13, wherein at least one of the shape or size of the aperture of said aperture stop is varied in accordance with an exposure condition.

19. An exposure apparatus according to claim 13, wherein the size of the aperture of said aperture stop is varied in accordance with the pattern formed on said mask.

20. A projection exposure apparatus for forming a pattern formed on a mask on a photosensitive substrate through a projection optical system, comprising:

an illumination optical system that illuminates said mask;

a first aperture stop, disposed within a pupil plane of said illumination optical system, that defines rectilinearly at least a part of an outline of a light source image formed on the pupil plane;

a blind, disposed in a plane conjugate with a pattern surface of said mask in said illumination optical system, that limits an illumination area with which said mask is illuminated; and

a second aperture stop, disposed within a pupil plane of said projection optical system, that defines a rectilinear edge corresponding to a rectilinear edge of said first aperture stop so as to shield a part of diffracted light generated with said pattern.

21. A projection exposure apparatus for forming a pattern formed on a mask on a photosensitive substrate through a projection optical system, comprising:

an illumination optical system that illuminates said mask; and

an aperture stop, disposed within or in the vicinity of a pupil plane of said projection optical system, and having a rectilinear edge corresponding to an outline of a light source image formed on a pupil plane of said illumination optical system so as to shield a part of diffracted light generated with said pattern.

22. A projection exposure apparatus according to claim 21, wherein said pattern comprises a pattern periodically arrayed in a predetermined direction, and said rectilinear edge extends in a direction orthogonal to said predetermined direction.

23. A projection exposure apparatus according to claim 21, further comprising:

a blind, disposed in a plane conjugate with a pattern surface of said mask in said illumination optical system, that limits an illumination area with which said mask is illuminated.

24. A method for making a projection exposure apparatus comprising:

providing a projection optical system that transfers a pattern formed on a mask, said pattern exhibiting a periodicity in a predetermined direction, onto a substrate; and

providing a first aperture stop disposed within or in the vicinity of a pupil plane of said projection optical system, and having an edge extending in a direction orthogonal to said predetermined direction.

25. A method according to claim 24, further comprising:

providing an illumination optical system that illuminates said mask; and

a second aperture stop disposed within or in the vicinity of a pupil plane of said illumination optical system, that rectilinearly defines at least a portion of an outline of a light source image formed thereat.

26. A projection exposure method in which a pattern formed on a first surface, and exhibiting a periodicity in a predetermined direction, is transferred onto a second surface through a projection optical system, wherein:

an image of said pattern is transferred onto said second surface through an aperture stop while shielding, with said aperture stop, a part of diffracted light generated with said pattern, said aperture stop being disposed on or in the vicinity of a pupil plane of said projection optical system and having an edge extending in a direction orthogonal to said predetermined direction.

27. A projection exposure method according to claim 26, wherein said first surface is illuminated with an illumination optical system, wherein said edge extending in a direction orthogonal to said predetermined direction corresponds to an outline of a light source image formed on a pupil plane of said illumination optical system.

28. An exposure method according to claim 26, wherein the size of the aperture of said aperture stop is varied in accordance with an exposure condition.

29. A projection exposure method in which a pattern formed on a first surface, and exhibiting a periodicity in a predetermined direction, is transferred onto a second surface through a projection optical system, wherein:

an image of said pattern is transferred onto said second surface through a stop while shielding, with said stop, a part of diffracted light generated with said pattern, said stop being provided on a Fourier transform plane of the first surface or on a plane in the vicinity thereof within said projection optical system, and having an aperture showing a line symmetry with respect to an axis passing through an optical axis of said projection optical system, extending in a direction orthogonal to said predetermined direction, and having an outline at least a part of which is rectilinear.

30. An exposure method according to claim 29, wherein a size of the aperture of said stop is adjusted before the image of the pattern is transferred onto said second surface.