Projection exposure apparatus and device manufacturing method

• US 6,266,192 B1
• Filed: 02/27/1998
• Issued: 07/24/2001
• Est. Priority Date: 02/28/1997
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Hirose, Ryusho, Sekine, Yoshiyuki
• Primary Examiner(s): CHANG, AUDREY Y
• Application Number:
  US09/031,762
• Time in Patent Office: 1,243 Days
• Field of Search: 359/565, 359/566, 359/569, 355/53, 355/67
• US Class Current: 359/569
• CPC Class Codes: G02B 27/0043 in projection exposure systems, e.g. microlithographic systems
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 27/4222 in projection exposure systems, e.g. photolithographic systems
• CPC Class Codes: G02B 27/4277 being separated by an air space
• CPC Class Codes: G03F 7/2002 with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
• CPC Class Codes: G03F 7/70241 Optical aspects of refractive lens systems, i.e. comprising only refractive elements
• 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

Abstract

A projection exposure apparatus includes an illumination optical system for illuminating a mask with light from a light source and a projection optical system having at least one diffractive optical element, for projecting an image of a pattern of the mask, as illuminated, onto a substrate. The at least one diffractive optical element is adapted to produce first diffraction light of an order to be used for projection of the image and second diffraction light of an order different from that of the first diffraction light. A portion of the second diffraction light is projected onto the substrate to provide a substantially uniform intensity distribution.

Claims

1. A projection exposure apparatus, comprising:

an illumination optical system for illuminating a mask with light from a light source; and

a projection optical system having at least one diffractive optical element, for projecting an image of a pattern of the mask, as illuminated, onto a substrate, wherein said at least one diffractive optical element is adapted to produce first diffraction light of an order contributable for projecting the image and second diffraction light of an order different from that of the first diffraction light, wherein an intensity distribution, upon the substrate, of a portion of the second diffraction light to be superposed with the image of the pattern upon the substrate is substantially uniform.

2. An apparatus according to claim 1, wherein said diffractive optical element is disposed at or adjacent to the position of an aperture stop of said projection optical system.

3. An apparatus according to claim 2, wherein another portion of the second diffraction light is not to be projected onto the substrate but to be projected on an inside wall of a lens barrel for supporting said projection optical system.

4. An apparatus according to claim 2, wherein said projection optical system comprises a plurality of diffractive optical elements which are disposed at or adjacent to an aperture stop of said projection optical system, for producing the first and second diffraction lights.

5. A projection exposure apparatus, comprising:

an illumination optical system for illuminating a mask with light from a light source; and

a projection optical system having a plurality of lenses and at least one diffractive optical element, for projecting an image of a pattern of the mask, as illuminated, onto a substrate, wherein said diffractive optical element is adapted to produce first diffraction light of an order to be used for projection of the image and second diffraction light of an order different from that of the first diffraction light, and wherein an intensity distribution, upon the substrate, of a portion of the second diffraction light to be superposed with the image of the pattern upon the substrate is substantially uniform while another portion of the second diffraction light is not to be projected onto the substrate.

6. An apparatus according to claim 5, wherein said diffractive optical element is disposed at or adjacent to the position of an aperture stop of said projection optical system.

7. An apparatus according to claim 6, wherein said projection optical system comprises at least two diffractive optical elements disposed at or adjacent to an aperture stop of said projection optical system, for producing the first and second diffraction lights.

8. An apparatus according to claim 7, wherein, when the distance between the mask and the substrate is D, the distance from the position of the aperture stop to the position of an i-th diffractive optical element is d_i, and the height of a maximum light ray at the aperture stop position that determines the numerical aperture of said projection optical system and the incidence height thereof to the i-th diffractive optical element are H and h_i, respectively, the following relations are satisfied with respect to each diffractive optical element:

9. An apparatus according to claim 7, wherein said plurality of lenses includes at least one aspherical lens.

10. An apparatus according to claim 7, wherein said diffractive optical element corrects axial chromatic aberration of said plurality of lenses, as well as coma of color.

11. An apparatus according to claim 7, wherein there are two diffractive optical elements and outermost gratings of said two diffractive optical elements have respective spatial frequencies fR₁ and fR₂ that satisfy the following relation:

12. An apparatus according to claim 7, wherein said apparatus includes a light source and the light source in selected from a group consisting of a KrF excimer laser, an ArF excimer laser and a F₂ laser.

13. An apparatus according to claim 7, wherein said projection optical system uses a glass material of quartz only.

14. An apparatus according to claim 7, wherein said projection optical system uses glass materials of quartz and fluorite only.

15. An apparatus according to claim 7, wherein the image of the pattern contains a line width not greater than 0.25 micron.

16. An apparatus according to claim 7, wherein the image of pattern is sequentially projected onto different portions of the substrate through a step-and-repeat process.

17. An apparatus according to claim 7, wherein the image of the pattern is sequentially projected onto different portions of the substrate through a step-and-scan process.

18. An apparatus according to claim 6, wherein the other portion of the second diffraction light, which is not to be projected onto the substrate is projected onto an inside wall of a lens barrel for supporting said projection optical system.

19. An apparatus according to claim 6, wherein, when the distance between the mask and the substrate is D, the distance from the position of the aperture stop to the position of said diffractive optical element is d, and the height of a maximum light ray at the aperture stop position that determines the numerical aperture of said projection optical system and the incidence height thereof to said diffractive optical element are H and h, respectively, the following relations are satisfied:

20. An apparatus according to claim 6, wherein said plurality of lenses includes at least one aspherical lens.

21. A projection exposure apparatus for projecting a pattern of a first object onto a second object through a projection optical system, said projection optical system comprising:

first and second diffractive optical elements disposed at or adjacent to the position of an aperture stop; and

at least one aspherical lens,

wherein, when the distance from the aperture stop to the i-th diffractive optical element is d_i, the distance from the first object to the second object is D, and the height of maximum light height, at the aperture stop position, that determines the numerical aperture of said projection optical system and the incidence height thereof to the i-th diffractive optical element are H and h_i, respectively, the following relations are satisfied;

22. A projection exposure apparatus for projecting a pattern of a first object onto a second object through a projection optical system, said apparatus comprising:

first and second diffractive optical elements disposed at or adjacent to the position of an aperture stop, wherein, when the distance from the aperture stop to the i-th diffractive optical element is d_i, the distance from the first object to the second object is D, and the height of maximum light height, at the aperture stop position, that determines the numerical aperture of said projection optical system and the incidence height thereof to the i-th diffractive optical element are H and h_i, respectively, the following relations are satisfied;

23. An apparatus according to claim 22, wherein said first and second diffractive optical elements are disposed on the opposite sides of the aperture stop.

24. An apparatus according to claim 23, wherein outermost gratings of said first and second diffractive optical elements have respective spatial frequencies fR₁ and fR₂ that satisfy the following relation:

25. An apparatus according to claim 22, wherein said first and second diffractive optical elements are disposed on a side of the aperture stop facing the first object.

26. An apparatus according to claim 22, wherein said first and second diffractive optical elements are disposed on a side of the aperture stop facing the second object.

27. An apparatus according to claim 22, wherein said first and second diffractive optical elements are set so that an intensity distribution, upon the second object, of a portion of the diffraction light not contributable to the projection, which portion is incident on a region of the second object where the pattern is projected, is uniform.

28. An apparatus according to claim 22, wherein said first and second diffractive optical elements are effective to correct axial chromatic aberration and color coma aberration of said projection optical system.

29. A projection exposure apparatus for projecting a pattern of a first object onto a second object through a projection optical system, said apparatus comprising:

first and second diffractive optical elements disposed on the opposite sides of an aperture stop, respectively, wherein said first and second diffractive optical elements are set so that an intensity distribution, upon the second object, of a portion of the diffraction light not contributable to the projection, which portion is incident on a region of the second object where the pattern is projected, is uniform.

31. A device manufacturing method comprising the steps of:

projecting a pattern of a reticle onto a wafer by use of a projection exposure apparatus as recited in any one of claims 29 or 30; and

performing, after the pattern projection, a development process to the wafer.

30. A projection exposure apparatus for projecting a pattern of a first object onto a second object through a projection optical system, said apparatus comprising:

first and second diffractive optical elements disposed on the opposite sides of an aperture stop, respectively, wherein outermost gratings of said first and second diffractive optical elements have respective spatial frequencies fR₁ and fR₂ that satisfy the following relation;