Methods to clean a surface, a device manufacturing method, a cleaning assembly, cleaning apparatus, and lithographic apparatus

• US 20070251543A1
• Filed: 04/28/2006
• Published: 11/01/2007
• Est. Priority Date: 04/28/2006
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Singh, Mandeep
• Granted Patent: US 7,628,865 B2
• Time in Patent Office: Days
• US Class Current: 134/1
• CPC Class Codes: G03F 7/70925 Cleaning, i.e. actively freeing apparatus from pollutants, e.g. using plasma cleaning
• CPC Class Codes: G21K 1/003 Manipulation of charged particles by using radiation pressure, e.g. optical levitation acceleration of charged particles H05H5/00, H05H7/00, H05H9/00, H05H11/00, H05H13/00

Abstract

An embodiment of the invention provides a method to clean a surface. The method includes at least partly liberating contaminants from the surface with a contaminant liberating device, and capturing the contaminants that have been at least partly liberated with a contaminant removal device, the contaminant removal device generating at least one optical trap to trap the contaminants that have been at least partly liberated. Embodiments of the invention also provide a device manufacturing method, a method to clean a surface of an optical element, a cleaning assembly and cleaning apparatus, and a lithographic apparatus.

Claims

1. A method to clean a surface, the method comprising:

at least partly liberating contaminants from the surface with a contaminant liberating device; and

capturing the contaminants that have been at least partly liberated with a contaminant removal device, the contaminant removal device generating at least one optical trap to trap the contaminants that have been at least partly liberated.

2. A method according to claim 1, wherein the contaminant liberating device is configured to treat the surface and the contaminants by applying to the surface and contaminants at least one selected from the group comprising:

a fluid, a liquid, a plasma, an electromagnetic field, a radiation beam, and a particle beam.

3. A method according to claim 1, wherein the contaminant liberating device comprises a laser device that directs a particle liberating beam of radiation against the surface to be cleaned to at least ablate and/or thermally dislodge contaminants thereon.

4. A method according to claim 1, wherein the at least one optical trap is generated by an optical tweezer and/or an optical spanner.

5. A method according to claim 1, wherein the contaminant removal device generates at least one focused beam of laser radiation to provide the at least one optical trap.

6. A method according to claim 1, wherein the contaminant liberating device and/or the contaminant removal device is configured to transfer orbital angular momentum to the contaminants.

7. A method according to claim 1, wherein the contaminant liberating device and the contaminant removal device are provided by the same cleaning device, the cleaning device being configured to generate at least one optical trap to transfer orbital angular momentum to at least one contaminant and to capture at least one contaminant.

8. A method according to claim 1, wherein the at least one optical trap is moved along the surface, without having obtained and/or obtaining positional coordinates of contaminant particles on the surface.

9. A method according to claim 1, wherein the at least one optical trap is moved along the surface such that the at least one optical trap reaches substantially each part of the surface within a certain cleaning period, and such that the at least one optical trap can encounter one or more contaminant particles that may be present on or near the surface.

10. A method according to claim 1, wherein the contaminant liberating device treats one or more parts of the surface to at least partly liberate contaminants, and wherein the at least one optical trap is moved to or near each surface part that has been treated by the contaminant liberating device to capture the at least partly liberated contaminants.

11. A method according to claim 1, wherein the at least one optical trap is moved from at least a first position to a second position to transport particles trapped by the trap and/or to move particles away from the surface.

12. A method to clean a surface, the method comprising:

moving at least one optical trap along the surface to at least partly liberate and/or capture contaminant particles without knowing positional coordinates of such particles.

13. A device manufacturing method, comprising:

transferring a pattern from a patterning device onto a substrate; and

generating at least one optical trap to optically liberate, trap and/or capture particles.

14. A method according to claim 13, wherein the particles are located on or near the patterning device, and/or on or near the substrate, and wherein the at least one optical trap is generated on or near the patterning device, and/or on or near the substrate, respectively.

15. A method according to claim 13, further comprising:

projecting a patterned radiation beam onto the substrate with a projection system, wherein the particles are located on or near at least a part of the projection system, and wherein the at least one optical trap is generated on or near the projection system part.

16. A method to clean a surface of an optical element, the method comprising:

at least partly liberating and/or capturing contaminant particles, present on the surface of the optical element with at least one optical trap.

17. A method according to claim 16, wherein the optical element is selected from the group comprising:

a lens, a mirror element, a reticle, an illumination system, an adjuster, an integrator, a condenser, a radiation collector, a foil trap, and an optical filter.

18. An assembly for cleaning a surface, the assembly comprising:

at least one contaminant liberating device constructed and arranged to at least partly liberate contaminants from the surface to be cleaned; and

at least one particle trapping apparatus configured to generate at least one optical trap.

19. An assembly according to claim 18, wherein the trapping apparatus is configured to trap particles that have been at least partly liberated from the surface by the liberating device.

20. An assembly according to claim 18, wherein the contaminant liberating device is configured to reduce or break a force between contaminant particles and the surface of the optical element, and/or to ablate and thermally dislodge contaminants from the surface, using electromagnetic fields.

21. An assembly according to claim 18, wherein the contaminant liberating device comprises a dry laser cleaning device or a steam laser cleaning device.

22. An assembly according to claim 18, wherein the assembly is configured to move the at least one optical trap, or the surface to be cleaned, or both, with respect to each other.

23. An assembly according to claim 18, wherein the contaminant liberating device is constructed and arranged to subsequently treat various parts of the surface to at least partly liberate contaminants from those parts, and wherein the particle trapping apparatus is configured to move the at least one optical trap to at least one part of the surface which is to be, is, and/or has been treated by the contaminant liberating device.

24. An assembly according to claim 18, wherein the at least one optical trap is generated by an optical tweezer and/or an optical spanner.

25. An assembly according to claim 18, wherein the particle trapping apparatus is arranged to focus at least one beam of laser radiation on or near the surface to be cleaned, to provide the at least one optical trap on or near that surface.

26. A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, the apparatus comprising at least one assembly according to claim 18.

27. A cleaning apparatus for cleaning a surface, the apparatus being configured to generate at least one optical trap, and to move the at least one optical trap, or the surface, or both, with respect to each other, to at least partly liberate and/or capture one or more contaminant particles that are present on the surface, without having obtained and/or obtaining positional coordinates of such particles prior to liberating and/or capture respective of such particles.

28. A cleaning apparatus for cleaning a surface, the apparatus being configured to generate at least one optical trap, and to move the at least one optical trap along the surface, such that the at least one optical trap reaches substantially each part of the surface within a certain cleaning period, and such that the at least one trap can encounter one or more contaminant particles that are present on the surface.

29. An assembly comprising at least an optical element, as well as a particle trapping apparatus being configured to generate at least one optical trap, the assembly being configured such that the particle trapping apparatus can clean at least part of the optical element using the optical trap.

30. A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, the apparatus comprising at least one optical trap generator configured to generate at least one optical trap to liberate and/or capture particles in the lithographic apparatus.