Optical arrangement for exposure apparatus

• US 6,295,118 B1
• Filed: 10/28/1997
• Issued: 09/25/2001
• Est. Priority Date: 10/29/1996
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takeuchi, Seiji
• Primary Examiner(s): Mathews, Alan A.
• Application Number:
  US08/959,304
• Time in Patent Office: 1,428 Days
• Field of Search: 355/30, 355/52, 355/53, 355/55, 359/565, 359/573, 359/666, 359/667, 359/824, 359/292, 250/201.1, 250/201.2, 250/201.3
• US Class Current: 355/52
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G03F 7/70858 Environment aspects, e.g. pressure of beam-path gas, temperature pollution aspects G03F7/70916
• CPC Class Codes: G03F 7/70883 of optical system

Abstract

An optical arrangement includes a diffractive optical element and a curvature control system for changing curvature of the diffractive optical element. The optical arrangement can be incorporated into an exposure apparatus having an illuminating system for illuminating a mask having a pattern formed thereon and a projecting system for projecting the pattern of the mask onto a wafer, such that the projecting system includes a diffractive optical element and a curvature control system for changing curvature of the diffractive optical element.

Claims

1. An optical apparatus, comprising:

a diffractive optical element having a variable curvature, wherein said diffractive optical element has a relief type diffraction grating, of which a grating pitch decreases from a center toward an edge thereof; and

curvature varying means for varying the curvature of said diffractive optical element.

2. An optical apparatus according to claim 1, wherein said curvature varying means pushes or pulls a peripheral edge portion of said diffractive optical element to thereby change the curvature of said diffractive optical element.

3. An optical apparatus according to claim 1, wherein said curvature varying means varies a pressure, applied to a surface of said diffractive optical element, to thereby change the curvature of the surface of said diffractive optical element.

4. An optical apparatus according to claim 3, further comprising a second optical element and holding means for holding said second optical element, wherein said second optical element, said diffractive optical element and said holding means define a space, which is gas-tightly closed, and wherein said curvature varying means varies a pressure in the space to thereby vary the curvature of said diffractive optical element.

5. An optical apparatus according to claim 4, wherein the space is filled with an inert gas.

6. An optical apparatus according to claim 1, further comprising measuring means for measuring the curvature of said diffractive optical element, wherein said varying means varies the curvature of said diffractive optical element on the basis of the measurement by said measuring means.

7. An optical apparatus according to claim 6, further comprising memorizing means for storing correlation information about a control amount of said varying means and the curvature of said diffractive optical element, wherein said varying means varies the curvature of said diffractive optical element on the basis of a control amount determined in accordance with the measurement by said measuring means and the correlation information stored by said memorizing means.

8. An exposure apparatus, comprising:

illuminating means for illuminating a mask having a pattern formed thereon; and

projecting means for projecting the pattern of the mask onto a wafer, said projecting means including (i) a diffractive optical element having a variable curvature, wherein said diffractive optical element has a relief type diffraction grating, of which a grating pitch decreases from a center toward an edge thereof, and (ii) varying means for varying the curvature of said diffractive optical element.

9. An apparatus according to claim 8, wherein said varying means pushes or pulls a peripheral edge portion of said diffractive optical element to thereby change the curvature of said diffractive optical element.

10. An apparatus according to claim 8, wherein said varying means varies a pressure, applied to at least one surface of said diffractive optical element, to thereby change the curvature of said diffractive optical element.

11. An apparatus according to claim 10, further comprising a second optical element and holding means for holding said second optical element, wherein said second optical element, said diffractive optical element and said holding means define a space which is gas-tightly closed, and said varying means varies a pressure in the space to thereby change the curvature of said diffractive optical element.

12. An apparatus according to claim 11, wherein the space is filled with an inert gas.

13. An apparatus according to claim 8, further comprising optical characteristic measuring means for measuring an optical characteristic of said projecting means, wherein said varying means varies the curvature of said diffractive optical element on the basis of the measurement by said optical characteristic measuring means.

14. An apparatus according to claim 13, further comprising memorizing means for storing correlation information about a control amount of said varying means and the optical characteristic of said projecting means, wherein said varying means controls the magnitude of curvature of said diffractive optical element on the basis of a control amount determined in accordance with the measurement by said optical characteristic measuring means and the correlation information stored by said memorizing means.

15. An apparatus according to claim 13, wherein said optical characteristic measuring means includes alignment detecting means for detecting an alignment error between the mask and the wafer, and said optical characteristic measuring means determines the optical characteristic of said projecting means on the basis of the alignment error detected by said alignment detecting means.

16. An apparatus according to claim 8, further comprising measuring means for measuring the curvature of the surface of said diffractive optical element, wherein said varying means varies the curvature of the surface of said diffractive optical element on the basis of the measurement by said measuring means.

17. An apparatus according to claim 16, further comprising memorizing means for storing correlation information about a control amount of said varying means and the curvature of said diffractive optical element, wherein said varying means varies the curvature of said diffractive optical element on the basis of a control amount determined in accordance with the measurement by said measuring means and the correlation information stored by said memorizing means.

18. A device manufacturing method, comprising the steps of:

providing an exposure apparatus as recited in any one of claims 8 to 17;

illuminating, by the illuminating means, a mask having a device pattern formed thereon;

projecting, by the projecting means, the pattern of the mask onto a wafer, to print an image of the device pattern of the mask onto the wafer; and

developing the wafer.

19. An optical apparatus, comprising:

a diffractive optical element having a variable curvature, wherein said diffractive optical element has a relief type diffraction grating, of which a grating pitch decreases from a center toward an edge thereof; and

varying means for varying a pressure applied to at least one surface of said diffractive optical element, to thereby change a curvature of said diffractive optical element.

20. An apparatus according to claim 19, further comprising a second optical element, and holding means for holding said second optical element, wherein said second optical element, said diffractive optical element and said holding means define a space, which is gas-tightly closed, and said varying means varies a pressure in the space to thereby change the curvature of the at least one surface of said diffractive optical element.

21. An apparatus according to claim 20, wherein the space is filled with an inert gas.

25. An exposure apparatus, comprising:

illuminating means for illuminating a mask having a pattern formed thereon; and

projecting means for projecting the pattern of the mask onto a wafer, said projecting means including an optical apparatus as recited in any one of claims 19 to 24.

26. A device manufacturing method, comprising the steps of:

providing an exposure apparatus as recited in claim 25;

illuminating, by the illuminating means, a mask having a device pattern formed thereon;

projecting, by the projecting means, the pattern of the mask onto a wafer, to print an image of the device pattern of the mask onto the wafer; and

developing the wafer.

22. An optical apparatus, comprising:

a diffractive optical element having a variable curvature, wherein said diffractive optical element has a relief type diffraction grating, of which a grating pitch decreases from a center toward an edge thereof;

measuring means for measuring a curvature of said diffractive optical element; and

varying means for varying the curvature of said diffractive optical element on the basis of the measurement by said measuring means.

23. An apparatus according to claim 22, further comprising memorizing means for storing correlation information about a control amount of said varying means and the curvature of said diffractive optical element, wherein said varying means varies the curvature of said diffractive optical element on the basis of a control amount determined in accordance with the measurement by said measuring means and the correlation information stored by said memorizing means.

24. An optical apparatus, comprising:

a diffractive optical element having a variable curvature, wherein said diffractive optical element has a relief type diffraction grating, of which a grating pitch decreases from a center toward an edge thereof;

measuring means for measuring a shape of said diffractive optical element; and

varying means for varying the shape of said diffractive optical element on the basis of the measurement by said measuring means.

27. An exposure apparatus, comprising:

illuminating means for illuminating a mask having a pattern formed thereon;

projecting means for projecting the pattern of the mask onto a wafer; and

measuring means for measuring an optical characteristic of said projecting means, wherein said projecting means includes (i) a diffractive optical element having a variable curvature, wherein said diffractive optical element has a relief type diffraction grating, of which a grating pitch decreases from a center toward an edge thereof and (ii) varying means for varying a shape of said diffractive optical element on the basis of the measurement by said measuring means.