Method and device for controlling fluid flow in an optical assembly

• US 6,847,431 B2
• Filed: 03/10/2003
• Issued: 01/25/2005
• Est. Priority Date: 03/10/2003
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Coon, Derek, Fay, Bernard
• Primary Examiner(s): MATHEWS, ALAN A
• Application Number:
  US10/384,969
• Publication Number:
  US 20040179174A1
• Time in Patent Office: 687 Days
• Field of Search: 355/30, 355/53, 359/509
• US Class Current: 355/30
• CPC Class Codes: G03F 7/70833 Mounting of optical systems, e.g. mounting of illumination system, projection system or stage systems on base-plate or ground
• CPC Class Codes: G03F 7/70933 Purge, e.g. exchanging fluid or gas to remove pollutants

Abstract

An optical assembly (222) for directing and/or focusing a beam of light energy for an exposure apparatus (10) includes an optical housing (240) and one or more optical elements (242) that cooperate to form an optical cavity (270) having one or more stagnant flow areas (272). The optical assembly (222) also includes one or more flow diverters (246) for improving the flow a replacement fluid (250) in the stagnant flow areas (272) of the optical cavity (270) during purging of the optical assembly (222) with the replacement fluid (250).

Claims

1. An optical assembly for directing a beam of light, the optical assembly for use with a replacement fluid from a fluid source, the optical assembly comprising:

an optical housing that defines an optical cavity, the optical housing including an inlet port that is in fluid communication with the fluid source so that the replacement fluid from the fluid source is directed into the optical cavity and flows in the optical cavity, the optical cavity including a stagnant flow area;

an optical element secured to the optical housing;

a first fluid passage provided in the optical cavity and allowing the replacement fluid to flow from a first Portion of the optical cavity on one side of the optical element to a second portion of the optical cavity on another side of the optical element; and

a flow diverter positioned in the optical cavity, the flow diverter redirecting the flow of the replacement fluid in the optical cavity so that the replacement fluid flows into the stagnant flow area.

2. The optical assembly of claim 1 including a plurality of spaced apart flow diverters positioned within the optical cavity, each flow diverter diverting the flow of replacement fluid in the optical cavity.

3. The optical assembly of claim 1 wherein the flow diverter is a vane positioned in the optical cavity that causes the flow of the replacement fluid in the optical cavity to flow into the first stagnant flow area.

4. The optical assembly of claim 1 wherein the flow diverter is a fan that causes the replacement fluid in the optical cavity to flow into the stagnant flow area.

5. The optical assembly of claim 4 wherein the fan pulls the replacement fluid into the stagnant flow area.

6. The optical assembly of claim 4 wherein the fan pushes the replacement fluid into the stagnant flow area.

7. The optical assembly of claim 1 further comprising an element mount that is generally annular ring shaped and the element mount includes the first fluid passage.

8. The optical assembly of claim 1 further comprising a first element mount and a second element mount that are spaced apart along an optical axis, wherein the first element mount includes the first fluid passage and the second element mount includes a second fluid passage, and wherein the first fluid passage is substantially opposite relative to the optical axis from the second fluid passage.

9. The optical assembly of claim 8 wherein the first element mount and the second element mount cause a somewhat serpentine shaped flow pattern in at least a portion of the optical cavity.

10. The optical assembly of claim 1 wherein the optical cavity includes a plurality of spaced apart stagnant flow areas and the optical assembly includes a plurality of spaced apart flow diverters positioned in the optical cavity, each flow diverter redirecting the flow of the replacement fluid in the optical cavity so that the replacement fluid flows into each stagnant flow area.

11. An exposure apparatus including an illumination source and the optical assembly of claim 1 positioned near the illumination source.

12. A device manufactured with the apparatus according to claim 11.

13. A wafer on which an image has been formed by the apparatus of claim 11.

14. A method for purging an optical cavity of an optical assembly, the optical assembly including an optical element and a stagnant flow area, the method comprising the steps of:

providing a fluid source of a replacement fluid;

directing the replacement fluid into the optical cavity;

providing a fluid passage to allow the replacement fluid to flow from a first portion of the optical cavity on one side of the optical element to a second portion of the optical cavity on another side of the optical element; and

redirecting the flow of the replacement fluid into the stagnant flow area of the optical cavity with a flow diverter positioned in the optical cavity.

15. The method of claim 14 wherein the step of redirecting includes redirecting the flow of replacement fluid with a plurality of spaced apart flow diverters positioned within the optical cavity.

16. The method of claim 14 wherein the flow diverter is a vane positioned in the optical cavity that causes the flow of the replacement fluid in the optical cavity to flow into the stagnant flow area.

17. The method of claim 14 wherein the flow diverter is a fan that causes the replacement fluid in the optical cavity to flow into the stagnant flow area.

18. The method of claim 14 further comprising the step of securing the optical element to an optical housing with an element mount and wherein the fluid passage is integrated into the element mount.

19. The method of claim 14 wherein the optical cavity includes a plurality of spaced apart stagnant flow areas and the step of redirecting includes the step of redirecting the flow of the replacement fluid with a plurality of spaced apart flow diverters in the optical cavity so that the replacement fluid flows into each stagnant flow area.

20. A method for making an exposure apparatus for transferring an image from a reticle to a wafer, the method comprising the steps of:

providing an illumination system that directs an illumination beam at the reticle; and

providing an optical assembly that is purged by the method of claim 14.

21. A method for making an object including at least the photolithography process, wherein the photolithography process transfers an image onto the object utilizing the apparatus made by the method of claim 20.

22. A method of making a wafer utilizing the apparatus made by the method of claim 20 to transfer an image onto the wafer.

23. A method for making an optical assembly for directing a beam of light, the optical assembly for use with a replacement fluid from a fluid source, the method comprising the steps of:

providing an optical housing that defines an optical cavity, the optical cavity including a stagnant flow area;

securing an optical element to the optical housing;

directing a replacement fluid from a fluid source into the optical cavity;

providing a fluid passage to allow the replacement fluid to flow from a first portion of the optical cavity on one side of the optical element to a second portion of the optical cavity on another side of the optical element; and

redirecting the replacement fluid into the stagnant flow area with a fluid diverter positioned within the optical cavity.

24. The method of claim 23 wherein the step of redirecting includes redirecting the flow of replacement fluid with a plurality of spaced apart flow diverters positioned within the optical cavity.

25. The method of claim 23 wherein the flow diverter is a vane positioned in the optical cavity that causes the flow of the replacement fluid in the optical cavity to flow into the stagnant flow area.

26. The method of claim 23 wherein the flow diverter is a fan that causes the replacement fluid in the optical cavity to flow into the stagnant flow area.

27. The method of claim 23 further comprising the step of securing the optical element to the optical housing with an element mount and wherein the fluid passage is integrated into the element mount.

28. The method of claim 23 wherein the optical cavity includes a plurality of spaced apart stagnant flow areas and the step of redirecting includes the step of redirecting the flow of the replacement fluid with a plurality of spaced apart flow diverters in the optical cavity so that the replacement fluid flows into each stagnant flow area.

29. A method for making an exposure apparatus for transferring an image from a reticle to a wafer, the method comprising the steps of:

providing an illumination system that directs an illumination beam at the reticle; and

providing an optical assembly made by the method of claim 23.

30. A method for making an object including at least the photolithography process, wherein the photolithography process transfers an image onto the object utilizing the apparatus made by the method of claim 29.

31. A method of making a wafer utilizing the apparatus made by the method of claim 29 to transfer an image onto the wafer.

32. An optical assembly for directing a beam of light, the optical assembly for use with a replacement fluid from a fluid source, the optical assembly comprising:

an optical housing that defines an optical cavity, the optical housing including an inlet port that is in fluid communication with the fluid source so that the replacement fluid from the fluid source is directed into the optical cavity and flows in the optical cavity, the optical cavity including a stagnant flow area;

an optical element secured to the optical housing; and

a flow diverter positioned in the optical cavity, wherein the flow diverter is a vane that redirects the flow of the replacement fluid in the optical cavity so that the replacement fluid flows into the stagnant flow area.

33. A method for purging an optical cavity of an optical assembly, the optical assembly including an optical element and a stagnant flow area, the method comprising the steps of:

providing a fluid source of a replacement fluid;

directing the replacement fluid into the optical cavity; and

redirecting the flow of the replacement fluid into the stagnant flow area of the optical cavity with a flow diverter positioned in the optical cavity, wherein the flow diverter is a vane that causes the flow of the replacement fluid in the optical cavity to flow into the stagnant flow area.

34. A method for making an optical assembly for directing a beam of light, the optical assembly for use with a replacement fluid from a fluid source, the method comprising the steps of:

providing an optical housing that defines an optical cavity, the optical cavity including a stagnant flow area;

securing an optical element to the optical housing;

directing a replacement fluid from a fluid source into the optical cavity; and

redirecting the replacement fluid into the stagnant flow area with a fluid diverter positioned within the optical cavity, wherein the flow diverter is a vane that causes the flow of the replacement fluid in the optical cavity to flow into the stagnant flow area.

35. An optical assembly for directing a beam of light, the optical assembly for use with a replacement fluid from a fluid source, the optical assembly comprising:

an optical housing that defines an optical cavity, the optical housing including an inlet port that is in fluid communication with the fluid source so that the replacement fluid from the fluid source is directed into the optical cavity and flows in the optical cavity;

a first optical element; and

a first element mount that secures the first optical element to the optical housing, the first element mount including a first fluid passage that allows the replacement fluid to flow from a first portion of the optical cavity on one side of the first optical element to a second portion of the optical cavity on another side of the first optical element, the first fluid passage being substantially arch shaped.

36. The optical assembly of claim 35 further comprising a second optical element that is spaced apart from the first element mount along an optical axis, and a second element mount that secures the second optical element to the optical housing, the second element mount including a second fluid passage that allows the replacement fluid to flow from a first side of the second optical element to a second side of the first optical element, the second fluid passage being substantially arch shaped.

37. The optical assembly of claim 36 wherein the first fluid passage is substantially opposite relative to the optical axis from the second fluid passage.

38. The optical assembly of claim 36 wherein the first element mount and the second element mount cause a somewhat serpentine shaped flow pattern in at least a portion of the optical cavity.