EP-4736302-A1 - RELUCTANCE ACTUATOR, POSITIONING DEVICE, STAGE APPARATUS, LITHOGRAPHIC APPARATUS

EP4736302A1EP 4736302 A1EP4736302 A1EP 4736302A1EP-4736302-A1

Abstract

The invention provides a reluctance actuator configured to exert a substantially upward force on an object, that is displaceable by a mover of a positioning device in a horizontal direction, the reluctance actuator comprising: a first member configured to be connected to the object, a second member configured to be connected to the mover, the first and second member forming a magnetic flux path comprising a gap between the first member and the second member, a permanent magnet arranged in the magnetic flux path to generate a bias magnetic flux in the magnetic flux path, the bias magnetic flux causing a bias upward force on the first member and a coil configured to engage with either the first member or the second member and configured to, when energized, generate a variable magnetic flux in the magnetic flux path, the variable magnetic flux causing a variable force on the first member.

Inventors

HUIBERTS, Sjoerd, Martijn
Kimman, Maarten, Hartger
Rovers, Johannes, Marinus, Maria

Assignees

ASML Netherlands B.V.

Dates

Publication Date: 20260506
Application Date: 20240604

Claims (15)

1. A reluctance actuator configured to exert a substantially upward force on an object, that is displaceable by a mover of a positioning device in a horizontal direction, the reluctance actuator comprising: a first member configured to be connected to the object; a second member configured to be connected to the mover; the first and second member forming a magnetic flux path comprising a gap between the first member and the second member; a permanent magnet arranged in the magnetic flux path to generate a bias magnetic flux in the magnetic flux path, the bias magnetic flux causing a bias upward force on the first member; a coil configured to engage with either the first member or the second member and configured to, when energized, generate a variable magnetic flux in the magnetic flux path, the variable magnetic flux causing a variable force on the first member; a first surface of the first member and a first surface of the second member which face each other across the gap are configured to maintain a magnetic flux resistance of the magnetic flux path substantially constant for a displacement of the first member relative to the second member in the horizontal direction over a predetermined distance D.
2. The reluctance actuator according to claim 1, wherein the first member comprising a C-core arranged in a substantially vertical plane, the second member comprising a C-core arranged in a substantially horizontal plane.
3. The reluctance actuator according to claim 1, wherein the first member comprising a C-core arranged in a substantially vertical plane, the second member comprising a C-core arranged in the substantially vertical plane, the C-core of the second member substantially enclosing the C-core of the first member.
4. The reluctance actuator according to any of the preceding claims, further comprising a connection member, the connection member having a bottom end connected to the first member and a top end configured to be connected to the object, whereby the top end is, during use, arranged above a top surface of the second member.
5. The reluctance actuator according to claim 1, wherein a width W1 of the first surface of the first member in the horizontal direction is smaller than a width W2 of the first surface of the second member in the horizontal direction.
6. The reluctance actuator according to claim 1, wherein a width W1 of the first surface of the first member in the horizontal direction is larger than a width W2 of the first surface of the second member in the horizontal direction.
7. The reluctance actuator according to any of the preceding claims, wherein the horizontal direction comprises a first horizontal direction and a second horizontal direction, the second horizontal direction being perpendicular to the first horizontal direction.
8. The reluctance actuator according to any of the preceding claims, wherein the first surface of the first member and the first surface of the second member are substantially horizontal surfaces.
9. The reluctance actuator according to any of the preceding claims, further comprising a sensor, such as a Hall sensor, arranged to measure a magnetic flux in the magnetic flux path.
10. The reluctance actuator according to claim 1, wherein the first member comprises a top plate and a bottom plate, the top plate and the bottom plate being parallel and spaced apart by a holder; the second member being arranged in between the top plate and the bottom plate and comprising: an inner magnetic cylinder; a radially magnetized permanent magnet arranged concentrically about the inner magnetic cylinder, as the permanent magnet; a cylindrical coil arranged about the inner magnetic cylinder, as the coil; an outer magnetic cylinder arranged concentrically about the radially magnetized permanent magnet; whereby top surfaces of the inner magnetic cylinder and the outer magnetic cylinder are spaced apart from a bottom surface of the top plate over a distance DI, forming a first gap of the gap; whereby bottom surfaces of the inner magnetic cylinder and the outer magnetic cylinder are spaced apart from a top surface of the bottom plate over a distance D2, forming a second gap of the gap.
11. The reluctance actuator according to any of the preceding claims, wherein the bias magnetic flux follows a first magnetic flux path of the magnetic flux path and wherein the variable magnetic flux follows a second magnetic flux path of the magnetic flux path.
12. A positioning device for positioning an object table, the positioning device comprising: a linear or planar motor for positioning the object table over comparatively large distances, the linear or planar motor comprising: a stator; a mover configured to displace the object table relative to the stator; wherein the positioning device further comprises one or more reluctance actuators according to any of the preceding claims, whereby first members of the one or more reluctance actuators are configured to be connected to the object table, as the object, and whereby second members of the one or more reluctance actuators are connected to the mover.
13. A stage apparatus comprising an object table and a positioning device according to claim 12 for positioning the object table.
14. A lithographic apparatus comprising a stage apparatus according to claim 13.
15. An exposure apparatus comprising a stage apparatus according to claim 13.

Description

RELUCTANCE ACTUATOR, POSITIONING DEVICE, STAGE APPARATUS, LITHOGRAPHIC APPARATUS CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority of EP application 23182537.3 which was filed on 29 June 2023 and which is incorporated herein in its entirety by reference. FIELD [0002] The present invention relates to reluctance actuators and positioning devices for use in a lithographic apparatus. BACKGROUND [0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern (also often referred to as “design layout” or “design”) of a patterning device (e.g., a mask) onto a layer of radiation- sensitive material (resist) provided on a substrate (e.g., a wafer). [0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements have continually been reduced while the amount of functional elements, such as transistors, per device has been steadily increasing over decades, following a trend commonly referred to as ‘Moore’s law’. To keep up with Moore’s law the semiconductor industry is chasing technologies that enable to create increasingly smaller features. To project a pattern on a substrate a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features which are patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm and 13.5 nm. A lithographic apparatus, which uses extreme ultraviolet (EUV) radiation, having a wavelength within a range of 4 nm to 20 nm, for example 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than a lithographic apparatus which uses, for example, radiation with a wavelength of 193 nm. [0005] In order to ensure an accurate positioning of the pattern on the substrate, it is important to ensure that the patterning device, holding the pattern, and the substrate are accurately positioned relative to each other. In order to achieve this, positioning devices are applied which often combine one or more electromagnetic motors, for displacing the patterning device or substrate over comparatively large distances, and one or more electromagnetic actuators, for displacing the patterning device or substrate over comparatively small distances, with a high accuracy. [0006] At the same time, there is a constant need to increase the throughput of a lithographic apparatus, which typically requires an increase in power for both the electromagnetic motors and the actuators. Achieving an increase in throughput using known positioning devices is found to be difficult, in particular with respect to the applied electromagnetic motors for the comparatively large displacements. This difficulty is at least partly caused by the applied electromagnetic actuators. The currently applied actuators have mainly been optimised to achieve an accurate positioning and a high efficiency. As a result, such actuators typically operate with very small operating ranges. It has been observed that these small operating ranges pose a limit to the design freedom of the positioning device, thus limiting the options to achieve a higher throughput. There is therefore a need for a different type of actuator which enables a larger design freedom for a positioning device. SUMMARY [0007] It is an objective of the present invention to provide an actuator enabling a larger design freedom when the actuator is applied in a positioning device of a lithographic apparatus. [0008] According to an aspect of the invention, there is provided a reluctance actuator configured to exert a substantially upward force on an object, that is displaceable by a mover of a positioning device in a horizontal direction, the reluctance actuator comprising: a first member configured to be connected to the object; a second member configured to be connected to the mover; the first and second member forming a magnetic flux path comprising a gap between the first member and the second member; a permanent magnet arranged in the magnetic flux path to generate a bias magnetic flux in the magnetic flux path, the bias magnetic flux causing a bias upward force on the first member; a coil configured to engage with either the first member or the second member and configured to, when energized, generate a variable magnetic flux in the magnetic flux path, the variable magnetic flux causing a variable force on the first member; a first surface of the first member and a first surface of the second member which face each other across the gap are configured to maintain a magnetic flux resistance of the magnetic flux path substantially constant for a displacement of the first member relative to the second member in the horizontal direction over a predetermined distance D. [0009] According to another aspect of