Moving beam with respect to diffractive optics in order to reduce interference patterns

• US 20070242253A1
• Filed: 04/13/2006
• Published: 10/18/2007
• Est. Priority Date: 04/13/2006
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Visser, Huibert, Baselmans, Johannes, De Jager, Pieter, Vink, Henri
• Granted Patent: US 7,948,606 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70058 Mask illumination systems

Abstract

A system and method are used to form incoherent beams from at least a partially coherent beam, such that interference or speckle patterns are substantially eliminated. A rotating optical element directs the partially coherent beam to reflect from an angular distribution changing element to form an incoherent beam. The partially coherent beam can be directed at valying angles or positions onto the angular distribution changing element through rotation of the rotating optical element. The angles can vary as a function of time.

Claims

1. A system, comprising:

a source of radiation that produces at least a partially coherent beam;

an angular distribution changing element; and

a rotating optical element that is configured to (a) receive the partially coherent beam from the source of radiation and (b) direct the received partially coherent beam to reflect from the angular distribution changing element to form an incoherent beam,

wherein the partially coherent beam is directed at varying angles or positions onto the angular distribution changing element based on a rotation speed of the rotating optical element, the angles varying as a function of time.

2. The system of claim 1, wherein the angular distribution changing element comprises a diffuser or a diffuser and a reflecting device.

3. The system of claim 2, wherein the diffuser comprises a wet etched or holographic diffuser.

4. The system of claim 1, wherein the angular distribution changing element comprises a diffractive optical element or a diffractive optical element and a reflecting device.

5. The system of claim 1, wherein the angular distribution changing element comprises a refractive optical element, a refractive optical element and lens, or a refractive optical element and a reflecting device.

6. The system of claim 1, wherein the angular distribution changing element comprises a zone lens, a Fresnel zone lens, a zone plate, or a Fresnel zone plate or a reflecting device and a zone lens, a Fresnel zone lens, a zone plate, or a Fresnel zone plate.

7. The system of claim 1, wherein the rotating optical element comprises a rotating mirror.

8. The system of claim 7, wherein the rotating mirror comprises a rotating polygonal mirror.

9. The system of claim 1, wherein the rotating optical element comprises a piezoelectric table.

10. The system of claim 1, wherein the rotating optical element comprises an opto-electric modulator.

11. The system of claim 1, wherein the angular distribution changing element is configured to increase angular distribution of the beam of radiation.

12. The system of claim 1, wherein the angular distribution changing element includes a reflecting surface having an optical power.

13. The system of claim 1, wherein the rotating optical element includes reflecting surfaces having optical power.

14. The system of claim 1, further comprising:

an illuminator, wherein the rotating optical element is configured to direct the incoherent beam onto the illuminator.

15. The system of claim 1, wherein the rotating optical element is configured to reflect the incoherent beam from the angular distribution changing element onto an illuminator, an optical system, or a patterning device.

16. A lithography system, comprising:

an illumination system that generates an illumination beam of radiation, comprising,

a source of radiation,

a rotating optical element, and

an angular distribution changing element;

a patterning device that patterns the illumination beam of radiation; and

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

17. The lithography system of claim 16, wherein:

the rotating optical element is configured to (a) receive the partially coherent beam from the source of radiation and (b) direct the received partially coherent beam to reflect from the angular distribution changing element to form an incoherent beam, and

the partially coherent beam is directed at varying angles or positions onto the angular distribution changing element based on a rotation speed of the rotating optical element, the angles varying as a function of time.

18. The lithography system of claim 17, wherein the rotating optical element is further configured to receive the incoherent beam from the angular distribution changing element.

19. The lithography system of claim 18, wherein the illumination system further comprises:

an illuminator, wherein the rotating optical element is configured to direct the incoherent beam onto the illuminator.

20. The lithography system of claim 16, wherein the angular distribution changing element comprises a diffuser, a wet etched diffuser, a holographic diffuser, a diffractive optical element, a refractive optical element, a zone lens, a Fresnel zone lens, a zone plate, or a Fresnel zone plate.

21. The lithography system of claim 20, wherein the angular distribution changing element further comprises a lens or a reflecting device.

22. The lithography system of claim 16, wherein the rotating optical element comprises a rotating mirror, a rotating polygonal mirror, a piezoelectric table, or an opto-electric device.

23. The lithography system of claim 16, wherein at least one of the angular distribution changing element or the rotating optical element includes a reflecting surface having optical power.

24. A device manufacturing method, comprising:

(a) using a rotating optical element to direct at least a partially coherent beam to reflect from an angular distribution changing element to form an incoherent beam;

(b) forming an illumination beam from the incoherent beam,

(c) patterning the illumination beam; and

(d) projecting the patterned illumination beam onto a target portion of a substrate.

25. The method of claim 24, wherein step (b) comprises directing the incoherent beam back onto the rotating optical element to form the illumination beam.

26. The method of claim 25, wherein the rotating optical element directs the incoherent beam onto an illuminator or an optical system to produce the illumination beam.

27. The method of claim 24, wherein the partially coherent beam is directed at varying angles or positions onto the angular distribution changing element by the rotating optical element, the angles varying as a function of time.

28. The method of claim 24, further comprising using a diffuser, a wet etched diffuser, a holographic diffuser, a diffractive optical element, a refractive optical element, a zone lens, a Fresnel zone lens, a zone plate, or a Fresnel zone plate as the angular distribution changing element.

29. The method of claim 28, further comprising using a reflecting device or a lens in the angular distribution changing element.

30. The method of claim 24, further comprising using a rotating mirror, a rotating polygonal mirror as the rotating optical element, a piezoelectric table, or a opto-electric device.

31. The method of claim 24, further comprising forming a reflecting surface having optical power on at least one of the angular distribution changing element or the rotating optical element.

32. A laser that outputs an incoherent output beam, comprising:

a source of radiation that produces at least a partially coherent beam;

an angular distribution changing element, and

a rotating optical element that is configured to (a) receive the partially coherent beam from the source of radiation and (b) direct the received partially coherent beam to reflect from the angular distribution changing element to form the incoherent output beam,

wherein the partially coherent beam is directed at varying angles or positions onto the angular distribution changing element based on a rotation speed of the rotating optical element, the angles varying as a function of time.

33. The laser of claim 32, wherein the rotating optical element is further configured to receive the incoherent beam from the angular distribution changing element.

34. The laser of claim 32, wherein the angular distribution changing element comprises a diffuser, a wet etched diffuser, a holographic diffuser, a diffractive optical element, a refractive optical element, a zone lens, a Fresnel zone lens, a zone plate, or a Fresnel zone plate.

35. The laser of claim 34, wherein the angular distribution changing element further comprises a lens or a reflecting device.

36. The laser of claim 32, wherein the rotating optical element comprises a rotating mirror, a rotating polygonal mirror, a piezoelectric table, or an opto-electric device.

37. The laser of claim 32, wherein at least one of the angular distribution changing element or the rotating optical element includes a reflecting surface having optical power.

38. An illuminator that outputs an incoherent illumination beam, comprising:

a source of radiation that produces at least a partially coherent beam;

an angular distribution changing element; and

a rotating optical element that is configured to (a) receive the partially coherent beam from the source of radiation and (b) direct the received partially coherent beam to reflect from the angular distribution changing element to form the incoherent illumination beam,

wherein the partially coherent beam is directed at varying angles or positions onto the angular distribution changing element based on a rotation speed of the rotating optical element, the angles varying as a function of time.

39. The illuminator of claim 38, wherein the rotating optical element is further configured to receive the incoherent beam from the angular distribution changing element.

40. The illuminator of claim 38, wherein the angular distribution changing element comprises a diffuser, a wet etched diffuser, a holographic diffuser, a diffractive optical element, a refractive optical element, a zone lens, a Fresnel zone lens, a zone plate, or a Fresnel zone plate.

41. The illuminator of claim 40, wherein the angular distribution changing element further comprises a lens or a reflecting device.

42. The illuminator of claim 38, wherein the rotating optical element comprises a rotating mirror, a rotating polygonal mirror, a piezoelectric table, or an opto-electric device.

43. The illuminator of claim 38, wherein at least one of the angular distribution changing element or the rotating optical element includes a reflecting surface having optical power.