Optical system for transforming numerical aperture

• US 20070183054A1
• Filed: 02/06/2006
• Published: 08/09/2007
• Est. Priority Date: 02/06/2006
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Ryzhikov, Lev, Vladmirksy, Yuli
• Granted Patent: US 7,532,403 B2
• Time in Patent Office: Days
• US Class Current: 359/619
• CPC Class Codes: G03F 7/70075 Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection
• CPC Class Codes: G03F 7/70208 Multiple illumination paths, e.g. radiation distribution devices, microlens illumination systems, multiplexers or demultiplexers for single or multiple projection systems
• CPC Class Codes: G03F 7/70275 Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices

Abstract

A system and method are used to form illumination light beams having desirable divergence and directivity. The illumination light beams are shaped using a pupil defining element and a field defining element. Then, divergence or numerical apertures of the light generated by these elements is modified using an optical element that either re-images the light onto planes conjugate to one or both of the pupil defining element and a field defining element or transforms a numerical aperture of light produced by one or both of the pupil defining element and a field defining element.

Claims

1. An optical system, comprising:

an optical element that receives a beam and generates a plurality of beams therefrom; and

an multiple aperture optical device that receives the plurality of beams and re-images the plurality of beams onto an image plane, which is conjugate to the optical element, to create a plurality of corresponding beams, each of the plurality of corresponding beams having a numerical aperture that is less than a numerical aperture of each of the plurality of beams.

2. The optical system of claim 1, wherein the optical element comprises a diffractive or refractive optical element.

3. The optical system of claim 1, wherein the multiple aperture optical device comprises a lens array.

4. The optical system of claim 3, wherein the lens array comprises a fly'"'"'s eye lens.

5. The optical system of claim 1, wherein the multiple aperture optical device comprises a lens relay comprising first and second lens arrays arranged in series.

6. The optical system of claim 5, wherein the first and second lens arrays are fly'"'"'s eye lenses.

7. The optical system of claim 1, wherein the first and second lens arrays are configured to maintain double telecentricity within the optical system.

8. The optical system of claim 1, wherein the optical element comprises a pupil defining element, and the optical system further comprises:

a first condenser that condenses the plurality of corresponding beams;

a field defining element that generates a field defined condensed beam;

a second condenser that condenses the field defined condensed beam; and

a relay that directs the condensed field defined condensed beam onto a patterning device.

9. The optical system of claim 8, wherein:

the patterning device comprises an array of individually controllable elements.

10. The optical system of claim 1, wherein the optical element comprises a pupil defining element, and the optical system further comprises:

a first condenser that condenses the plurality of corresponding beams;

a field defining element that receives the condensed plurality of beams and generates a field defined beam therefrom;

another multiple aperture optical device that receives the field defined beam and generates another plurality of corresponding beams therefrom, each of the another plurality of corresponding beams having a numerical aperture that is less than a numerical aperture of the field defined beam;

a second condenser that receives and condenses the another plurality of corresponding beams; and

a relay that receives and directs the condensed another plurality of corresponding beams onto a patterning device.

11. The optical system of claim 1, wherein the optical element comprises a field defining element, and the optical system further comprises:

a pupil defining element positioned to receive a beam from a radiation source and produce a pupil defined beam therefrom;

a first condenser that condenses the pupil defined beam and directs the condensed pupil defined beam as the beam received by the field defining element;

a second condenser that receives and condenses the plurality of corresponding beams; and

a relay that receives and directs the condensed plurality of corresponding beams and onto a patterning device.

12. The optical system of claim 1, wherein the multiple aperture optical device is configured to direct each corresponding beam in the plurality of corresponding beams onto corresponding portions of the image plane.

13. The optical system of claim 1, wherein the optical system is the illumination system of a lithography system, the lithography system further comprising:

an optical system, which is positioned after the multiple aperture optical device, that conditions the plurality of corresponding beams;

a patterning device that patterns the conditioned beam; and

a projection system that projects the patterned beam onto a target portion of a substrate.

14. An optical system, comprising:

an optical element that receives a beam and generates a first set of beamlets therefrom, the first set of beamlets having a first numerical aperture; and

a numerical aperture transformation device that receives the first set of beamlets and generates a second set of beamlets therefrom, each of the second set of beamlets having a second numerical aperture that is less than the first numerical aperture.

15. The optical system of claim 14, wherein the numerical aperture transformation device is configured to direct the second set of beamlets onto corresponding discrete locations of an image plane conjugate to the optical element.

16. The optical system of claim 14, wherein the numerical aperture transformation device comprises a lens array or a fly'"'"'s eye lens.

17. The optical system of claim 14, wherein the numerical aperture transformation device comprises an array of lens arrays or fly'"'"'s eye lenses.

18. The optical system of claim 14, wherein the numerical aperture transformation device is configured to maintain double telecentricity.

19. A method, comprising:

forming a first plurality of beams having a first numerical aperture from a beam of radiation; and

transforming the first plurality of beams having the first numerical aperture into a second plurality of beams each having a second numerical aperture, each of the second numerical apertures being less than the first numerical apertures.

20. The method of claim 19, further comprising:

directing the second plurality of beams having the second numerical aperture onto predetermined discrete portions of an image plane.

21. The method of claim 19, wherein the transforming step comprises using a lens array or a fly'"'"'s eye lens.

22. The method of claim 19, wherein the transforming step comprises using an array of lens arrays or an array of fly'"'"'s eye lenses.

23. The method of claim 19, further comprising:

patterning the second plurality of beams; and

projecting the patterned beams onto a substrate.

24. A method, comprising:

forming a plurality of beams from a beam of radiation using an optical device; and

re-imaging, either individually or as a group, the first plurality of beams onto an image plane that is conjugate to the optical device,

wherein double telecentricity is maintained during the re-imaging step.