Illumination system for a microlithography projection exposure installation

• US 7,714,983 B2
• Filed: 09/13/2004
• Issued: 05/11/2010
• Est. Priority Date: 09/12/2003
• Status: Active Grant

• Current Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss AG (Carl-Zeiss-Stiftung)
• Inventors: Maul, Manfred, Wangler, Johannes, Fiolka, Damian, Brotsack, Markus, Koehler, Jess, Singer, Wolfgang
• Primary Examiner(s): Kim; Peter B
• Assistant Examiner(s): RIDDLE, CHRISTINA A
• Application Number:
  US10/571,475
• Publication Number:
  US 20070165202A1
• Time in Patent Office: 2,066 Days
• Field of Search: 355 67- 72, 355/52, 355/53, 355/55, 355/77, 359/15, 359/19, 359/20, 359/619, 359/569, 359/575, 250/492.1, 250/492.2, 250/492.22, 250/548
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/702 Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems

Abstract

An illumination system for a microlithography projection exposure installation is used to illuminate an illumination field with the light from a primary light source (11). The illumination system has a light distribution device (25) which receives light from the primary light source and, from this light, produces a two-dimensional intensity distribution which can be set variably in a pupil-shaping surface (31) of the illumination system. The light distribution device has at least one optical modulation device (20) having a two-dimensional array of individual elements (21) that can be controlled individually in order to change the angular distribution of the light incident on the optical modulation device. The device permits the variable setting of extremely different illuminating modes without replacing optical components.

Claims

1. An illumination system for a microlithography projection exposure system for illuminating an illumination field with light from a primary light source, the illumination system comprising:

a light distribution device which receives light from the primary light source and which produces a two-dimensional intensity distribution in a pupil-shaping surface of the illumination system,

wherein the light distribution device variably sets the two-dimensional intensity distribution,

wherein the light distribution device comprises at least one optical modulation device which controllably changes an angular distribution of the light incident on the optical modulation device,

wherein the optical modulation device comprises an array of individual elements that are driven individually to change an angle of radiation incident on the individual elements,

wherein, between the light source and the optical modulation device, there is arranged an optical device which concentrates radiation incident on the optical device onto the individual elements of the optical modulation device,

wherein the optical device forms a plurality of beams from the incident radiation and concentrates each of the plurality of beams onto a respective individual element of the optical modulation device, and

wherein an axicon system is arranged between the optical modulation device and the pupil-shaping surface.

2. The illumination system according to claim 1, wherein the optical modulation device is controlled such that at least substantially all of the light intensity that is incident on the optical modulation device is deflected into a usable region of the pupil-shaping surface.

3. The illumination system according to claim 1, further comprising, between the optical modulation device and the pupil-shaping surface, an optical system which converts the angular distribution produced by the optical modulation device into a spatial distribution in the pupil-shaping surface.

4. The illumination system according to claim 3, wherein the optical system has a variable focal length.

5. The illumination system according to claim 3, wherein the axicon system is incorporated into the optical system.

6. The illumination system according to claim 1, wherein the optical modulation device is a reflective optical modulation device.

7. The illumination system according to claim 6, wherein the reflective optical modulation device is arranged obliquely with respect to an optical axis in the manner of a deflection mirror.

8. The illumination system according to claim 1, wherein, between the optical modulation device and the pupil-shaping surface, there is an optical distance such that angles between an optical axis and light beams belonging to the angular distribution in the region of the pupil-shaping surface are less than 5°

.

9. The illumination system according to claim 1, wherein the individual elements of the optical modulation device comprise an array of individual mirrors in at least one mirror arrangement.

10. The illumination system according to claim 9, wherein at least some of the individual mirrors have a flat mirror surface.

11. The illumination system according to claim 9, wherein at least some of the individual mirrors are curved mirrors with a finite mirror focal length.

12. The illumination system according to claim 11, wherein the mirror focal length is dimensioned such that radiation incident on the individual mirrors strikes the pupil-shaping surface in substantially focused form.

13. The illumination system according to claim 9, wherein the individual mirrors are adaptive mirrors, which are adjustable in shape.

14. The illumination system according to claim 9, wherein the individual mirrors of the mirror arrangement all have the same shape and size.

15. The illumination system according to claim 9, wherein the mirror arrangement comprises a first mirror group and at least a second mirror group, each mirror group comprises at least one individual mirror, and the individual mirrors of the mirror groups have at least one of differing sizes, differing shapes and differing curvatures.

16. The illumination system according to claim 9, wherein at least some of the individual mirrors of the mirror arrangement have an optical structure which forms a distribution of the radiation reflected from the respective individual mirror.

17. The illumination system according to claim 16, wherein the optical structure is a diffractive optical structure.

18. The illumination system according to claim 9, wherein some individual mirrors of the mirror arrangement are tilted relative to other individual mirrors of the mirror arrangement.

19. The illumination system according to claim 1, wherein the optical modulation device is an electro-optical element, and the array of individual elements is selected from the group consisting of controllable diffraction gratings and acousto-optical elements.

20. The illumination system according to claim 1, wherein the optical device comprises a two-dimensional array comprising telescope lens systems.

21. The illumination system according to claim 1, wherein the optical device comprises a diffractive optical array generator which transforms an incoming beam into a plurality of light beams concentrated on individual optical elements of the optical modulation device.

22. The illumination system according to claim 21, wherein the diffractive optical array generator is a Dammann grid.

23. The illumination system according to claim 1, further comprising, between the pupil-shaping surface and a plane of the illumination field, a light mixing device which mixes the light of the intensity distribution.

24. The illumination system according to claim 23, wherein the light mixing device comprises at least one integrator rod having an entry surface, and the pupil-shaping surface lies in the region of a plane which is located upstream of the entry surface and which is a Fourier-transformed plane in relation to the entry surface.

25. The illumination system according to claim 23, wherein the light mixing device comprises at least one fly'"'"'s eye condenser.

26. The illumination system according to claim 25, wherein the fly'"'"'s eye condensor has an entry surface, and the pupil-shaping surface lies in the region of the entry surface or a surface which is optically conjugate with respect to the entry surface.

27. The illumination system according to claim 25, further comprising a component which controls the optical modulation device such that individual radiation channels of the fly'"'"'s eye condenser are either at least substantially irradiated or at least substantially non-irradiated.

28. The illumination system according to claim 25, wherein the light distribution device comprises at least one diffractive optical element arranged optically between the optical modulation device and the pupil-shaping surface, which receives light emerging from the optical modulation device, and which modifies the light by introducing an angular distribution according to an effect function defined by the configuration of the diffractive optical element.

29. The illumination system according to claim 28, wherein a beam which emerges from an individual element of the optical modulation device is shaped by the diffractive optical element to conform to the shape and size of one single optical channel or a group of adjacent optical channels of the fly'"'"'s eye condenser.

30. The illumination system according to claim 28, wherein the diffractive optical element is a computer generated hologram.

31. The illumination system according to claim 25, wherein the fly'"'"'s eye condenser is not assigned any mask for the individual blocking of radiation channels.

32. The illumination system according to claim 1, wherein neither a fly'"'"'s eye condenser nor an integrator rod is arranged between the pupil-shaping surface and a plane of the illumination field.

33. The illumination system according to claim 1, wherein, in or in the vicinity of the pupil-shaping surface, there is arranged a raster element which shapes and homogenizes the intensity distribution in a following field plane of the illumination system.

34. The illumination system according to claim 1, further comprising a control device which drives individual elements of the optical modulation device, such that control signals which control the individual elements are varied as a function of the structure of a mask to be exposed.

35. The illumination system according to claim 1, wherein the optical device comprises a two-dimensional raster arrangement of optical elements or a diffractive optical array generator.