Actuation mechanism, optical apparatus, lithography apparatus and method of manufacturing devices

Patent metadata

Field	Value
Publication number	US-9785051-B2
Application number	US-201314435450-A
Country	US
Kind code	B2
Filing date	Sep 17, 2013
Priority date	Oct 15, 2012
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

An actuator to displace, for example a mirror, provides movement with at least two degrees of freedom by varying the currents in two electromagnets. A moving part includes a permanent magnet with a magnetic face constrained to move over a working area lying substantially in a first plane perpendicular to a direction of magnetization of the magnet. The electromagnets have pole faces lying substantially in a second plane closely parallel to the first plane, each pole face substantially filling a quadrant of the area traversed by the face of the moving magnet. An optical position sensor may direct a beam of radiation at the moving magnet through a central space between the electromagnets. The sizes of facets in a pupil mirror device may be made smaller in a peripheral region, but larger in a central region, thereby relaxing focusing requirements.

First claim

What is claimed is:

1. An actuation mechanism to provide movement with at least two degrees of freedom, the mechanism comprising a moving part and a static part, the moving part including a permanent magnet with a magnetic face constrained by a suspension that couples the moving part and the static part to move over a working area lying substantially in a first plane perpendicular to a direction of magnetization of the magnet, the static part comprising at least two electromagnets having pole faces lying substantially in a second plane closely parallel to the first plane, the pole faces being symmetrically distributed around a central position in the second plane and extending over substantially the whole area traversed by the face of the moving magnet.

2. The mechanism as claimed in claim 1 , wherein each electromagnet is a bipolar electromagnet having first and second pole faces located diametrically opposite one another in the second plane.

3. The mechanism as claimed in claim 1 , wherein the number of electromagnet pole faces is four, each of the pole faces has substantially the form of a quadrant of a circle or annulus, the pole faces together substantially covering a circular or annular area in the second plane.

4. The mechanism as claimed in claim 1 having an elongate form with a longitudinal axis perpendicular to the first and second planes, wherein the moving part is constrained to tilt about first and second axes orthogonal to the longitudinal axis when the magnet moves over the working area.

5. The mechanism as claimed in claim 1 , wherein a gap between the face of the permanent magnet and the pole faces of the electromagnets is less than 20% of the width of the magnet face.

6. The mechanism as claimed in claim 5 , wherein the gap between the face of the permanent magnet and the pole faces of the electromagnets is less than 15% of the width of the magnet face.

7. The mechanism as claimed in claim 6 , wherein the gap between the face of the permanent magnet and the pole faces of the electromagnets is less than 10% of the width of the magnet face.

8. The mechanism as claimed in claim 1 , wherein each pole face is located on the distal end of an elongate ferromagnetic core of its respective electromagnet, and wherein the cores for diametrically opposite pole faces have proximal ends connected together by ferromagnetic material.

9. The mechanism as claimed in claim 8 , wherein proximal ends of all the cores are connected via a common ferromagnetic base.

10. The mechanism as claimed in any claim 1 , further comprising a ferromagnetic shield surrounding at least the permanent magnet so as to shield it from magnetism when a plurality of such actuation mechanisms are placed side-by-side.

11. The mechanism as claimed in claim 1 , further comprising a position sensor configured to monitor a position of the moving part to enable feedback control of the position, the position sensor configured to direct a beam of radiation at a reflective surface arranged to move with the moving part of the mechanism and to detect deflection of a beam of radiation reflected from the reflective surface.

12. The mechanism as claimed in claim 11 , wherein the reflecting surface is on the moving magnet and the position sensor is configured to direct the beam of radiation at the moving magnet through a central space between the electromagnets and to detect deflection of the beam of radiation reflected from the moving magnet through the same central space.

13. The mechanism as claimed in claim 11 , wherein the position sensor is configured to direct the beam of radiation along an optical axis, wherein an output of the directed beam of radiation is located on the optical axis while a photo detector configured to detect the reflected radiation beam surrounds the optical axis so that the directed beam passes through the center of the photodetector.

14. The mechanism as claimed in claim 13 , wherein the photodetector comprises a plurality of photosensitive elements spaced around the optical axis.

15. The mechanism as claimed in claim 13 , wherein the directed beam of radiation has an annular intensity profile that is dark around the optical axis, such that reflected radiation is substantially not directed back to the output of the directed beam of radiation.

16. The mechanism as claimed in claim 11 , wherein the reflecting surface is curved.

17. The mechanism as claimed in claim 1 , wherein the moving magnet comprises SmCo material.

18. The mechanism as claimed in claim 1 in an elongate form, wherein a suspension section, the permanent magnet, the static part and a position sensor are stacked end-to-end.

19. The mechanism as claimed in claim 1 , wherein the moving part is supported by a resilient support arranged to provide a biasing force increasing in response to relative displacement between first and second parts and opposing a motive force, the mechanism further comprising a magnetic coupling between the first and second parts, the magnetic coupling being arranged to provide a counter-biasing force, the counter-biasing force partly opposing the biasing force to reduce the motive force used to effect a given displacement.

20. An optical apparatus comprising a series of optical components arranged to receive a radiation beam from a radiation source to process and deliver the beam to a target location, wherein the optical components include one or more movable optical components mounted on an actuator mechanism configured to provide movement with at least two degrees of freedom, the mechanism comprising a moving part and a static part, the moving part including a permanent magnet with a magnetic face constrained to move over a working area lying substantially in a first plane perpendicular to a direction of magnetization of the magnet, the static part comprising at least two electromagnets having pole faces lying substantially in a second plane closely parallel to the first plane, the pole faces being symmetrically distributed around a central position in the second plane and extending over substantially the whole area traversed by the face of the moving magnet, wherein the optical apparatus further comprises a controller and drive circuitry configured to energize the electromagnets to achieve a desired positioning of the or each movable optical component.

21. The optical apparatus as claimed in claim 20 , wherein the one or more movable optical components form part of an illumination system configured to condition the beam and deliver it to a target location on a patterning device, and the movable component is movable to vary an incidence angle of the conditioned beam at the target location.

22. The optical apparatus as claimed in claim 21 , comprising a plurality of such movable components with associated actuation mechanisms provided as part of a fly's eye illuminator.

23. The optical apparatus as claimed in claim 22 , wherein the movable components comprise field facet mirrors in a faceted field mirror device within the fly's eye illuminator, each movable field facet mirror controllable to direct a portion of the beam to a selected one of several associated pupil facet mirrors in a faceted pupil mirror device, and the several pupil facet mirrors are of different sizes, according to their position in the pupil mirror device.

24. The optical apparatus as claimed in claim 23 , wherein pupil facet mirrors in a peripheral region of the pupil mirror device are smaller than those in a cen

Assignees

• Asml Netherlands Bv

Inventors

• Van Schoot Jan Bernard Plechelmus
• Hol Sven Antoin Johan
• Buis Edwin Johan
• Rekkers Erik Maria
• De Vries Gosse Charles
• Botma Hako
• Van Dam Marinus Johannes Maria
• Van Gorkom Ramon Pascal

Classifications

• G02B7/1821 Primary

  for rotating or oscillating mirrors · CPC title

• G03F7/70116

  Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets · CPC title

• H01H2051/2218

  having at least one movable permanent magnet · CPC title

• H02K41/00

  Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path {(electromagnetic launchers F41B6/00)} · CPC title

• H01F7/0231

  Magnetic circuits with PM for power or force generation · CPC title