PROJECTION EXPOSURE TOOL FOR MICROLITHOGRAPHY WITH A MEASURING APPARATUS AND METHOD FOR MEASURING AN IRRADIATION STRENGTH DISTRIBUTION

• US 20100020302A1
• Filed: 07/22/2009
• Published: 01/28/2010
• Est. Priority Date: 01/23/2007
• Status: Active Grant

• Current Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss AG (Carl-Zeiss-Stiftung)
• Inventors: Freimann, Rolf
• Granted Patent: US 8,537,332 B2
• Time in Patent Office: Days
• US Class Current: 355/68
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01J 1/0411 using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction
• CPC Class Codes: G01J 1/0437 using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 1/4257 applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam monitoring arrangements for lasers in general H01S3/0014
• CPC Class Codes: G03F 7/70133 Measurement of illumination distribution, in pupil plane or field plane
• CPC Class Codes: G03F 7/70591 Testing optical components
• CPC Class Codes: G03F 7/706 Aberration measurement
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load
• CPC Class Codes: G03F 7/70941 Stray fields and charges, e.g. stray light, scattered light, flare, transmission loss

Abstract

A projection exposure tool (10) for microlithography with a measuring apparatus (36) disposed in an optical path (28) of the projection exposure tool (10) for the locally and angularly resolved measurement of an irradiation strength distribution. The measuring apparatus (36) includes a measuring field with an arrangement (56) of focusing optical elements (42) disposed at respective individual points of the measuring field (41), a common image plane (44) for the focusing optical elements (42), a locally resolving radiation detector (46) with a recording surface (48) for the locally resolved recording of a radiation intensity, the recording surface (48) being disposed in the common image plane (44), and the radiation detector outputting radiation intensity signals for a plurality of angle values indicative of a respective angularly resolved irradiation strength distribution for at least one of the individual measuring field points.

Claims

1. A projection exposure tool for microlithography comprising:

a measuring apparatus disposed in an optical path of the projection exposure tool for locally and angularly resolved measurement of an irradiation strength distribution, the measuring apparatus comprising;

a measuring field with an arrangement of focusing optical elements disposed at respective individual points of the measuring field,

a common image plane for the focusing optical elements, and

a locally resolving radiation detector with a recording surface for the locally resolved recording of a radiation intensity, the recording surface being disposed in the common image plane, the radiation detector outputting radiation intensity signals for a plurality of angle values indicative of a respective angularly resolved irradiation strength distribution for at least one of the individual points of the measuring field.

2. The projection exposure tool according to claim 1, wherein the radiation detector outputs radiation intensity signals for the plurality of angle values indicative of the respective angularly resolved irradiation strength distribution for each of the individual points of the measuring field.

7. The projection exposure tool according to claim 1,

further comprising a wafer plane for positioning a wafer to be exposed lithographically, and wherein the measuring apparatus is disposed in the region of the wafer plane.

8. The projection exposure tool according to claim 1,

wherein the focusing optical elements and the radiation detector are integrated into a separate module.

9. The projection exposure tool according to claim 1,

wherein a local resolution of the radiation detector is greater than an extent of individual ones of the focusing optical elements.

10. The projection exposure tool according to claim 1,

wherein the measuring apparatus measures the irradiation strength distribution at each of the points of the measuring field two-dimensionally angularly resolved.

11. The projection exposure tool according to claim 1,

wherein the focusing optical elements are arranged in a grid-form in a measuring plane.

12. The projection exposure tool according to claim 1,

further comprising a pinhole grid with a plurality of openings forming the focusing optical elements.

13. The projection exposure tool according to claim 12,

further comprising an illumination device for emitting electromagnetic radiation with a specific wavelength as the radiation, and the openings of the pinhole grid have respective diameters, each of which is at least twice as large as the wavelength.

14. The projection exposure tool according to claim 1,

wherein at least one of:

the measuring apparatus further comprises a polarizing filter, and the radiation detector is configured to be polarization-selective.

15. The projection exposure tool according to claim 1,

wherein at least one of:

the measuring apparatus further comprises a spectral filter, and the radiation detector is configured to be spectral-selective.

16. The projection exposure tool according to claim 1,

wherein the optical path comprises a bundle of individual rays, at the common image plane for the optical elements the individual rays have a maximum angular deviation α

_max in relation to the respective optical axes of the optical elements, and the optical elements have respective diameters P and respective focal lengths f which conform to the following relation;

P/(2f>

tan(α

_max).

17. The projection exposure tool according to claim 1,

wherein the measuring apparatus further comprises a shielding element for shielding individual ones of the focusing optical elements from irradiation.

18. The projection exposure tool according to claim 1,

wherein the measuring apparatus is disposed in a measuring plane, and further comprising an evaluation device establishing the irradiation strength distribution in the measuring plane and, in accordance with the irradiation strength distribution, calculates by ray optics an irradiation strength distribution into a target plane offset in relation to the measuring plane.

19. The projection exposure tool according to claim 18,

further comprising a REMA objective with an assigned pupil plane, a reticle masking device disposed in an aperture plane, a reticle plane, a projection objective with an assigned pupil plane, and a wafer plane, wherein the target plane is disposed between two planes, the two planes selected from the pupil plane of the REMA objective, the aperture plane, the reticle plane, the pupil plane of the projection objective and the wafer plane.

20. The projection exposure tool according to claim 1,

wherein the measuring apparatus further comprises a detector movement device moving the radiation detector in the common image plane.

21. The projection exposure tool according to claim 1,

further comprising an apparatus movement device moving the measuring apparatus in the optical path of the projection exposure tool.

22. The projection exposure tool according to claim 1,

wherein the measuring apparatus has at least one of:

a plurality of arrays of focusing optical elements, which arrays are adjacent to one another, and a plurality of locally resolving individual detector arrays adjacent to one another.

3. A projection exposure tool for microlithography comprising:

a reticle plane for positioning a reticle carrying a structured lithography mask,

a projection objective imaging the structured lithography mask onto a wafer,

a reticle masking device disposed in an aperture plane, and

a measuring apparatus for locally and angularly resolved measurement of an irradiation strength distribution,

the measuring apparatus comprising an arrangement of focusing optical elements,

a common image plane for the focusing optical elements, and a locally resolving radiation detector with a recording surface disposed in the common image plane for the locally resolved recording of a radiation intensity, and

the measuring apparatus being disposed in the region of a plane selected from a group of planes consisting of the reticle plane, a pupil plane of the projection objective, and the aperture plane.

4. The projection exposure tool according to claim 3, further comprising a REMA objective imaging a reticle masking device into the reticle plane, and

wherein the measuring apparatus is disposed in the region of a plane selected from a group of planes consisting of the reticle plane, the pupil plane of the projection objective, a pupil plane of the REMA objective, and the aperture plane.

5. The projection exposure tool according to claim 3, wherein:

the focusing optical elements are disposed at respective individual points of a measuring field, and

the radiation detector outputs radiation intensity signals for a plurality of angle values indicative of a respective angularly resolved irradiation strength distribution for at least one of the individual points of the measuring field.

6. The projection exposure tool according to claim 3,

wherein the measuring apparatus comprises a measuring field, the focusing optical elements are respectively disposed at individual points of the measuring field, and the measuring apparatus further comprises an evaluation device which establishes a respective angularly resolved irradiation strength distribution from the recorded radiation intensity for each of the individual points of the measuring field.

23. A method for measuring an irradiation strength distribution in an optical path of a projection exposure tool for microlithography, comprising:

arranging focusing optical elements at individual points of a measuring field in the optical path of the projection exposure tool such that the focusing optical elements have a common image plane,

arranging a locally resolving radiation detector such that a recording surface of the radiation detector lies in the common image plane,

locally resolved recording of respective intensities of electromagnetic radiation reaching the radiation detector, and

establishing a respective angularly resolved irradiation strength distribution for at least one of the individual measuring field points from the recorded radiation intensities.

24. The method according to claim 23, wherein:

the respective intensities are for a plurality of angle values indicative of the respective angularly resolved irradiation strength distribution for each of the individual points of the measuring field.