MIRROR ASSEMBLY WITH HEAT TRANSFER MECHANISM

• US 20150042970A1
• Filed: 03/07/2013
• Published: 02/12/2015
• Est. Priority Date: 03/22/2012
• Status: Active Grant

• Current Assignee: Nikon Research Corporation Of America (Nikon Corporation)
• Original Assignee: Nikon Corporation
• Inventors: Margeson, Christopher, Bow, Travis
• Granted Patent: US 10,371,920 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G02B 7/028 with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
• CPC Class Codes: G02B 7/181 with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
• CPC Class Codes: G02B 7/1815 with cooling or heating systems cooling arrangements for laser mirrors H01S3/0401
• CPC Class Codes: G02B 7/182 for mirrors
• 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 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/70316 Details of optical elements, e.g. of Bragg reflectors, extreme ultraviolet [EUV] multilayer or bilayer mirrors or diffractive optical elements
• CPC Class Codes: G03F 7/70891 Temperature

Abstract

A mirror assembly (32) for directing a beam (28) includes a base (450), and an optical element (454) that includes (i) a mirror (460), (ii) a stage (462) that retains the mirror (460), (iii) a mover assembly (464) that moves the stage (462) and the mirror (460) relative to the base (450), and (v) a thermally conductive medium (466) that is positioned between the stage (462) and the base (450) to transfer heat between the stage (462) and the base (450). The thermally conductive medium (466) has a thermal conductivity that is greater than the thermal conductivity of air. The thermally conductive medium (466) can include an ionic fluid or a liquid metal.

Claims

1-47. -47. (canceled)

48. An optical element assembly for directing a beam, the optical element assembly comprising:

a base; and

a first element that includes (i) an optical element, (ii) a mover assembly that is coupled to the optical element, the mover assembly moving the optical element about a first axis and about a second axis that is orthogonal to the first axis relative to the base, (iii) a transfer region that is connected to the optical element, and (iv) a thermally conductive medium positioned between the transfer region and the base to transfer heat from the transfer region to the base so that heat transferred with the thermally conductive medium does not cause thermal distortion of the mover assembly.

49. The optical element assembly of claim 48 wherein the mover assembly includes (i) a first axis movement assembly that moves the optical element about the first axis, the first axis movement assembly including a first flexure so that movement of the optical element about the first axis with the first axis movement assembly is decoupled from the movement of the optical element about the second axis;

and (ii) a second axis movement assembly that moves the optical element about the second axis, the second axis movement assembly including a second flexure so that movement of the optical element about the second axis with the second axis movement assembly is decoupled from the movement of the optical element about the first axis.

50. The optical element assembly of claim 49 wherein the mover assembly moves the optical element to move approximately about a movement point that is near a center of a reflective surface of the optical element.

51. The optical element assembly of claim 50 wherein the mover assembly includes a linkage that is coupled to the optical element, and a mover that pivots the linkage about a pivot axis;

wherein the movement point is in a movement plane defined by the first axis and the second axis, and wherein the pivot axis is not in the pivot plane.

52. The optical element assembly of claim 48 wherein the mover assembly includes (i) a first axis movement assembly that moves the optical element about the first axis, the first axis movement assembly including a first mover and a first flexure that couples the first mover to the optical element so that movement by the first mover causes movement of the optical element about the first axis without movement of the optical element about the second axis;

and (ii) a second axis movement assembly that moves the optical element about the second axis, the second axis movement assembly including a second mover and a second flexure that couples the second mover to the optical element so that movement by the second mover causes movement of the optical element about the second axis without movement of the optical element about the first axis.

53. The optical element assembly of claim 48 wherein the base includes at least one fluid passageway for directing a circulation fluid through the base.

54. The optical element assembly of claim 48 further comprising a fluid system that circulates the thermally conductive medium between the transfer region and the base, and wherein the thermally conductive medium has a thermal conductivity that is greater than the thermal conductivity of air.

55. The optical element assembly of claim 48 wherein the transfer region includes a plurality of spaced apart projections that are positioned near the base.

56. The optical element assembly of claim 48 wherein the thermally conductive medium is selected from the group that includes an ionic fluid and a liquid metal.

57. The optical element assembly of claim 48 wherein the base includes an element recess that receives at least a portion of the transfer region;

and wherein the shape of the element recess corresponds to the shape of the transfer region.

58. The optical element assembly of claim 57 wherein the transfer region includes a surface that is shaped somewhat similar to a truncated sphere;

and wherein the element recess defines an indentation that is shaped somewhat similar to a truncated sphere.

59. The optical element assembly of claim 48 further comprising a second element that is positioned adjacent to the first element, the second element including (i) an optical element, (ii) a mover assembly that is coupled to the optical element, the mover assembly moving the optical element about the first axis and about the second axis relative to the base, (iii) a transfer region that is connected to the optical element, and (iv) a thermally conductive medium positioned between the transfer region and the base to transfer heat from the transfer region to the base so that heat transferred with the thermally conductive medium does not cause thermal distortion of the mover assembly.

60. An exposure apparatus for transferring an image to a wafer, the exposure apparatus comprising:

a wafer stage that retains and positions the wafer;

an illumination source that generates a beam; and

the optical element assembly of claim 48 that directs the beam.

61. The optical element assembly of claim 48, wherein the optical element includes at least one of (i) a mirror;

(ii) a reflective surface;

or (iii) a lens.

62. An optical element assembly for directing a beam, the optical element assembly comprising:

a base that includes an element recess, and at least one fluid passageway for directing a circulation fluid through the base; and

an element that includes (i) an optical element having a reflective surface;

(ii) a mover assembly that is coupled to the optical element, the mover assembly moving the optical element about a first axis and about a second axis that is orthogonal to the first axis relative to the base about a movement point that is approximately at a center of the reflective surface, wherein the mover assembly includes a first axis movement assembly that moves the optical element about the first axis, the first axis movement assembly including a first flexure so that movement of the optical element about the first axis with the first axis movement assembly is decoupled from the movement of the optical element about the second axis; and

a second axis movement assembly that moves the optical element about the second axis, the second axis movement assembly including a second flexure so that movement of the optical element about the second axis with the second axis movement assembly is decoupled from the movement of the optical element about the first axis;

(iii) a stage that retains the optical element, the stage including transfer region that is positioned in the element recess, wherein the size and shape of the transfer region corresponds to the size and shape of the element recess; and

(iv) a thermally conductive medium positioned in the element recess between the transfer region and the base to transfer heat from the transfer region to the base so that heat transferred with the thermally conductive medium does not cause thermal distortion of the mover assembly.

63. The optical element assembly of claim 62 wherein the mover assembly includes a linkage that is coupled to the optical element, and a mover that pivots the linkage about a pivot axis;

wherein the movement point is in a movement plane defined by the first axis and the second axis, and wherein the pivot axis is not in the pivot plane.

64. The optical element assembly of claim 62 further comprising a fluid system that circulates the thermally conductive medium between the transfer region and the base, and wherein the thermally conductive medium has a thermal conductivity that is greater than the thermal conductivity of air.

65. The optical element assembly of claim 62 wherein the transfer region includes a surface that is shaped somewhat similar to a truncated sphere;

and wherein the element recess defines an indentation that is shaped somewhat similar to a truncated sphere.

66. A method for directing a beam, the method comprising the steps of:

providing a base;

positioning an optical element in a path of the beam;

moving the optical element with a mover assembly about a first axis and about a second axis that is orthogonal to the first axis relative to the base;

transferring heat away from the optical element with a transfer region that is connected to the optical element; and

transferring heat away from the transfer region with a thermally conductive medium positioned between the transfer region and the base so that heat transferred with the thermally conductive medium does not cause thermal distortion of the mover assembly.

67. The method of claim 66 wherein the step of moving the optical element includes the steps of (i) moving the optical element about the first axis with a first axis movement assembly, the first axis movement assembly including a first flexure so that movement of the optical element about the first axis is decoupled from the movement of the optical element about the second axis;

and (ii) moving the optical element about the second axis with a second axis movement assembly, the second axis movement assembly including a second flexure so that movement of the optical element about the second axis is decoupled from the movement of the optical element about the first axis.