Radiation Collector, Radiation Source and Lithographic Apparatus

• US 20160041374A1
• Filed: 03/24/2014
• Published: 02/11/2016
• Est. Priority Date: 04/17/2013
• Status: Abandoned Application

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: VANDERHALLEN, Ivo, STRUYCKEN, Alexander Matthijs, FRANKEN, Johannes Christiaan Leonardu
• Application Number:
  US14/780,151
• Publication Number:
  US 20160041374A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 19/0023 at least one surface having optical power
• CPC Class Codes: G02B 19/009 for use with infrared radiation
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B
• CPC Class Codes: G02B 5/09 Multifaceted or polygonal mirrors , e.g. polygonal scanning mirrors; Fresnel mirrors
• CPC Class Codes: G02B 5/10 with curved faces
• CPC Class Codes: G02B 7/1815 with cooling or heating systems cooling arrangements for laser mirrors H01S3/0401
• CPC Class Codes: G03F 7/70033 by plasma extreme ultraviolet [EUV] sources
• CPC Class Codes: G03F 7/70175 Lamphouse reflector arrangements or collector mirrors, i.e. collecting light from solid angle upstream of the light source
• CPC Class Codes: G03F 7/70575 Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength
• CPC Class Codes: G03F 7/70891 Temperature
• CPC Class Codes: G03F 7/7095 Materials, e.g. materials for housing, stage or other support having particular properties, e.g. weight, strength, conductivity, thermal expansion coefficient

Abstract

A radiation collector (141) comprising a plurality of reflective surfaces (400-405), wherein each of the plurality of reflective surfaces is coincident with part of one of a plurality of ellipsoids (40-45), wherein the plurality of ellipsoids have in common a first focus (12) and a second focus (16), each of the plurality of reflective surfaces coincident with a different one of the plurality of ellipsoids, wherein the plurality of reflective surfaces are configured to receive radiation originating from the first focus (12) and reflect the radiation to the second focus (16). An apparatus (820) shown in FIG. 11 comprising a cooling system (832) and a reflector (831), wherein the cooling system is configured to cool the reflector, the cooling system comprising: a porous structure (823) situated in thermal contact with the reflector, wherein the porous structure is configured to receive a coolant in a liquid phase state; a condenser (825) configured to receive coolant from (826) the porous structure in a vapour phase state, condense the coolant thereby causing the coolant to undergo a phase change to a liquid phase state and output the condensed coolant in the liquid phase state for entry (827) into the porous structure.

Claims

1. A radiation collector comprising:

a plurality of reflective surfaces, wherein each of the plurality of reflective surfaces is coincident with part of one of a plurality of ellipsoids,

wherein the plurality of ellipsoids have in common a first focus and a second focus,

each of the plurality of reflective surfaces coincident with a different one of the plurality of ellipsoids, and

the plurality of reflective surfaces are configured to receive radiation originating from the first focus and reflect the radiation to the second focus.

2. The radiation collector of claim 1, wherein the reflective surfaces are disposed around an optical axis of the radiation collector.

3. The radiation collector of claim 1, wherein the reflective surfaces extend circumferentially around the optical axis.

4. The radiation collector of claim 1, wherein the plurality of reflective surfaces have lengths that cause the radiation collector to act as a diffraction grating to infrared radiation.

6. The radiation collector of claim 1, wherein the plurality of reflective surfaces are joined by one or more intermediate surfaces.

7. The radiation collector of claim 6, wherein the intermediate surfaces each have a length of around cos θ

(n+¼

)λ

_IR where n is an integer, λ

_IR is the wavelength of infrared radiation to which the radiation collector acts as a diffraction grating and θ

is the angle of incidence of infrared radiation on the reflective surfaces of the radiation collector.

9. The radiation collector of claim 6, wherein each intermediate surface is arranged substantially parallel to a direction from the first focus to the corresponding intermediate surface.

10. The radiation collector of claim 6, wherein the intermediate surfaces are undercut behind the reflective surfaces.

11. The radiation collector of claim 6, wherein one or more holes are provided in at least one of the one or more intermediate surfaces.

12. The radiation collector of claim 1, wherein the plurality of reflective surfaces comprises more than 10 reflective surfaces.

13. The radiation collector of claim 1, wherein an inner reflective surface of the plurality of the reflective surfaces is coincident with an inner ellipsoid of the plurality of ellipsoids.

14. The radiation collector of claim 2, wherein the distance of each of the plurality of reflective surfaces from the optical axis increases with the size of the ellipsoid which each reflective surface is coincident with.

15. The radiation collector of claim 2, wherein the radiation collector is configured such that an available length along the optical axis is provided in which a contaminant trap may be positioned in between the radiation collector and the first and second focuses.

5. (canceled)

8. (canceled)

16. (canceled)

17. An apparatus comprising a cooling system and a reflector, wherein the cooling system is configured to cool the reflector, the cooling system comprising:

a porous structure situated in thermal contact with the radiation collector, wherein the porous structure is configured to receive a coolant in a liquid phase state; and

a condenser configured to receive coolant from the porous structure in a vapour phase state, condense the coolant thereby causing the coolant to undergo a phase change to a liquid phase state and output the condensed coolant in the liquid phase state for entry into the porous structure.

18. The apparatus of claim 17, wherein the porous structure comprises a material through which a capillary structure extends.

21. The apparatus of claim 18, wherein the cooling system is configured such that coolant is distributed through the porous structure by capillary action.

23. The apparatus of claim 17, further comprising a non-porous sheet configured to seal the porous structure from the reflector.

24. The apparatus of claim 23, wherein the non-porous sheet comprises a non-porous sheet of copper.

29. The apparatus of claim 17, wherein a surface of the substrate that is furthest from the porous layer is provided with a smoothing layer configured to provide a smooth surface.

31. The apparatus of claim 17, wherein the reflector comprises a radiation collector comprising:

a porous structure situated in thermal contact with the radiation collector, wherein the porous structure is configured to receive a coolant in a liquid phase state; and

a condenser configured to receive coolant from the porous structure in a vapour phase state, condense the coolant thereby causing the coolant to undergo a phase change to a liquid phase state and output the condensed coolant in the liquid phase state for entry into the porous structure.

19-20. -20. (canceled)

22. (canceled)

25-28. -28. (canceled)

30. (canceled)