Reticle gripper, reticle exchange device, exposure apparatus and reticle gripping method

Abstract

Embodiments herein describe a gripper is configured to support an item in an exposure apparatus. The gripper comprises a magnetorheological material, and a magnet configured to generate a magnetic field. The magnetorheological material is configured to be transitionable between a high stiffness state and a low stiffness state in response to the magnetic field. The magnet is arranged to transition the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and to transition the magnetorheological material to the low stiffness state when the gripper is away from the loading position.

Description

RETICLE GRIPPER. RETICLE EXCHANGE DEVICE. EXPOSURE APPARATUS AND RETICLE GRIPPING METHODCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 696,160 which was filed on September 18, 2024 and which is incorporated herein in its entirety by reference.FIELD

[0002] The present disclosure relates to a reticle gripper, a reticle exchange device comprising such as reticle gripper, an exposure apparatus comprising such a reticle gripper or reticle exchange device, and a method of supporting an item in an exposure 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 of a patterning device (e.g., a mask, a reticle) onto a layer of radiation-sensitive material (resist) provided on a substrate.

[0004] 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 can be formed on the substrate. A lithographic apparatus, which uses extreme ultraviolet (EUV) radiation, having a wavelength within the range 4-20 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] Reticles are critical and sensitive components for imparting patterns on substrates. A reticle handler may be used to move and position multiple reticles for scanning and / or patterning operations in a lithographic apparatus. Increased throughput of the lithographic apparatus may result in higher acceleration of movable parts such as scanning stages, which may result in an increase of disturbance forces. A gripper configured to hold a reticle may be provided with flexures to isolate the reticle from disturbance forces. For Reticle transfers from reticle handler to reticle stage a high stiffness may be desired. However, for disturbance force isolation a low stiffness may be desired, resulting in conflicting requirements.SUMMARY

[0006] Accordingly, the present disclosure provides a gripper, a reticle exchange device, an exposure apparatus and a method of supporting an item, that provide disturbance force isolation in a lithographic apparatus.In some embodiments, a gripper is configured to support an item in an exposure apparatus. The gripper comprises a magnetorheological material, and a magnet configured to generate a magnetic field. The magnetorheological material is configured to be transitionable between a high stiffness state and a low stiffness state in response to the magnetic field. The magnet is arranged to transition the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and to transition the magnetorheological material to the low stiffness state when the gripper is away from the loading position.

[0007] In some embodiments, a reticle exchange device comprises the gripper.

[0008] In some embodiments, an exposure apparatus comprises the gripper or the reticle exchange device.

[0009] In some embodiments, a method of supporting an item in an exposure apparatus is provided. The method comprises supporting the item by a gripper. The gripper comprises a magnetorheological material, and a magnet configured to generate a magnetic field. The method comprises transitioning the magnetorheological material between a high stiffness state and a low stiffness state in response to the magnetic field, comprising transitioning by the magnet the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and transitioning the magnetorheological material to the low stiffness state when the gripper is away from the loading position.

[0010] Further features of the disclosure, as well as the structure and operation of various embodiments of the disclosure, are described in detail below with reference to the accompanying drawings. It is noted that the disclosure is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.BRIEF DESCRIPTION OF THE DRAWINGS / FIGURES

[0011] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the disclosure and to enable a person skilled in the relevant art(s) to make and use the disclosure. Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0012] FIG. 1 shows a schematic illustration of a lithographic apparatus, according to some embodiments.

[0013] FIG. 2 shows a perspective schematic illustration of a reticle stage, according to some embodiments.

[0014] FIG. 3 shows a top plan view of the reticle stage of Figure 2.

[0015] FIG. 4 shows a perspective schematic illustration of a reticle exchange apparatus, according to some embodiments.

[0016] FIG. 5 shows a partial cross-sectional view of the reticle exchange apparatus of FIG. 4.

[0017] FIG. 6A shows a partial schematic illustration of a reticle exchange apparatus in an approach configuration, according to some embodiments.

[0018] FIG. 6B shows a partial schematic illustration of a reticle exchange apparatus in a first contact configuration, according to some embodiments.

[0019] FIG. 6C shows a partial schematic illustration of a reticle exchange apparatus in a full contact configuration, according to some embodiments.

[0020] FIG. 7A and 7B show a schematic illustration of a top view and side view, respectively, of a reticle gripper in a reticle exchange area, according to some embodiments.

[0021] FIGS. 8A and 8B show a schematic illustration of a top view and side view, respectively, of a reticle gripper in a reticle exchange area, according to some embodiments.

[0022] FIG. 9A and 9B show a schematic illustration of a top view and side view, respectively, of a reticle gripper in a reticle exchange area, according to some embodiments.

[0023] FIGS. 10A and 10B show a schematic illustration of atop view and side view, respectively, of a reticle gripper in a reticle exchange area, according to some embodiments.

[0024] The features of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. Additionally, generally, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.DETAILED DESCRIPTION

[0025] This specification discloses one or more embodiments that incorporate the features of this disclosure. The disclosed embodiment(s) merely exemplify the disclosure. The scope of the disclosure is not limited to the disclosed embodiment(s). The disclosure is defined by the claims appended hereto.

[0026] The embodiment(s) described, and references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0027] Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “on,” “upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship toanother element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0028] The term “about” as used herein indicates the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the term “about” can indicate a value of a given quantity that varies within, for example, 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

[0029] Embodiments of the disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the disclosure may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine- readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, and / or instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc., and in doing that may cause actuators or other devices to interact with the physical world.

[0030] Before describing such embodiments in more detail, however, it is instructive to present an example environment in which embodiments of the present disclosure may be implemented.

[0031] Exemplary Lithographic System

[0032] FIG. 1 shows a lithographic system comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and to supply the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

[0033] The illumination system IL is configured to condition the EUV radiation beam B before the EUV radiation beam B is incident upon the patterning device MA. Thereto, the illumination system IL can include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and faceted pupil mirror device 11 together provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The illumination system IL can include other mirrors or devices in addition to, or instead of, the faceted field mirror device 10 and faceted pupil mirror device 11.

[0034] After being thus conditioned, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B’ is generated. The projection system PS is configured to project the patterned EUV radiation beam B’ onto the substrate W. Forthat purpose, the projection system PS can comprise a plurality of mirrors 13, 14 that are configured to project the patterned EUV radiation beam B’ onto the substrate W held by the substrate table WT. The projection system PS can apply a reduction factor to the patterned EUV radiation beam B’, thus forming an image with features that are smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 can be applied. Although the projection system PS is illustrated as having only two mirrors 13, 14 in FIG. 1, the projection system PS can include a different number of mirrors (e.g. six or eight mirrors).

[0035] The substrate W can include previously formed patterns. Where this is the case, the lithographic apparatus LA aligns the image, formed by the patterned EUV radiation beam B’, with a pattern previously formed on the substrate W.

[0036] A relative vacuum, i.e. a small amount of gas (e.g. hydrogen) at a pressure well below atmospheric pressure, can be provided in the radiation source SO, in the illumination system IL, and / or in the projection system PS.

[0037] The radiation source SO can be a laser produced plasma (LPP) source, a discharge produced plasma (DPP) source, a hydrogen plasma source, a free electron laser (FEL), or any other radiation source that is capable of generating EUV radiation.

[0038] Exemplary Reticle Stage

[0039] FIGS. 2 and 3 show schematic illustrations of an exemplary reticle stage 200, according to some embodiments. Reticle stage 200 can include top stage surface 202, bottom stage surface 204, side stage surfaces 206, and clamp 300. In some embodiments, reticle stage 200 with clamp 300 can be implemented in lithographic apparatus LA. For example, reticle stage 200 can be support structure MT in lithographic apparatus LA. In some embodiments, clamp 300 can be disposed on top stage surface 202. For example, as shown in FIG. 2, clamp 300 can be disposed at a center of top stage surface 202 with clamp frontside 302 facing perpendicularly away from top stage surface 202.

[0040] In some lithographic apparatuses, for example, lithographic apparatus LA, a reticle stage 200 with a clamp 300 can be used to hold and position a reticle 408 for scanning or patterning operations. In one example, the reticle stage 200 can require powerful drives, large balance masses, and heavy frames to support it. In one example, the reticle stage 200 can have a large inertia and can weigh over 500 kg to propel and position a reticle 408 weighing about 0.5 kg. To accomplish reciprocating motions of the reticle 408, which are typically found in lithographic scanning or patterning operations, accelerating and decelerating forces can be provided by linear motors that drive the reticle stage 200.

[0041] In some embodiments, as shown in FIGS. 2 and 3, reticle stage 200 can include first encoder 212 and second encoder 214 for positioning operations. For example, first and second encoders 212, 214 can be interferometers. First encoder 212 can be attached along a first direction, for example, atransverse direction (i.e., X-direction) of reticle stage 200. And second encoder 214 can be attached along a second direction, for example, a longitudinal direction (i.e., Y-direction) of reticle stage 200. In some embodiments, as shown in FIGS. 2 and 3, first encoder 212 can be orthogonal to second encoder 214.

[0042] As shown in FIGS. 2 and 3, reticle stage 200 can include clamp 300. Clamp 300 is configured to hold reticle 408 in a fixed plane on reticle stage 200. Clamp 300 includes clamp frontside 302 and can be disposed on top stage surface 202. In some embodiments, clamp 300 can use mechanical, vacuum, electrostatic, or other suitable clamping techniques to hold and secure an object. In some embodiments, clamp 300 can be an electrostatic clamp, which can be configured to electrostatically clamp (i.e., hold) an object, for example, reticle 408 in a vacuum environment. Due to the requirement for EUV radiation to perform in a vacuum environment, vacuum clamps cannot be used to clamp a mask or reticle and instead electrostatic clamps can be used. For example, clamp 300 can include an electrode, a resistive layer on the electrode, a dielectric layer on the resistive layer, and burls projecting from the dielectric layer. In use, a voltage can be applied to clamp 300, for example, several kV. And current can flow through the resistive layer, such that the voltage at an upper surface of the resistive layer will substantially be the same as the voltage of the electrode and generate an electric field. Also, a Coulomb force, attractive force between electrically opposite charged particles, will attract an object to clamp 300 and hold the object in place. In some embodiments, clamp 300 can be a rigid material, for example, a metal, a dielectric, a ceramic, or a combination thereof.

[0043] Exemplary Reticle Exchange Apparatus

[0044] FIGS. 4 through 6 show schematic illustrations of an exemplary reticle exchange apparatus 100, according to some embodiments. Reticle exchange apparatus 100 can be configured to minimize reticle exchange time, particle generation, and contact forces or stresses from clamp 300 and / or reticle 408 to reduce damage to clamp 300 and reticle 408 and increase overall throughput in a reticle exchange process, for example, in a lithographic apparatus LA.

[0045] As shown in FIGS. 4 and 5, reticle exchange apparatus 100 can include reticle stage 200, clamp 300, and in-vacuum robot 400. In-vacuum robot 400 can include reticle handler 402.

[0046] In some embodiments, reticle handler 402 can be a rapid exchange device (RED), which is configured to efficiently rotate and minimize reticle exchange time. For example, reticle handler 402 can save time by moving multiple reticles from one position to another substantially simultaneously, instead of serially.

[0047] In some embodiments, as shown in FIG. 4, reticle handler 402 can include one or more reticle handler arms 404. In some embodiments, reticle handler arms 404 may be referred to herein as rapid exchange device (RED) grippers. Reticle handler arm 404 can include reticle baseplate 406. Reticle baseplate 406 can be configured to hold an object, for example, reticle 408. In some embodiments, reticle baseplate 406 may be referred to herein as a reticle base frame.

[0048] In some embodiments, reticle baseplate 406 can be an extreme ultraviolet inner pod (EIP) for a reticle. In some embodiments, reticle baseplate 406 includes reticle baseplate frontside 407, and reticle 408 includes reticle backside 409.

[0049] In some embodiments, as shown in FIGS. 4 and 5, reticle baseplate 406 can hold reticle 408 such that reticle baseplate frontside 407 and reticle backside 409 each face top stage surface 202 and clamp frontside 302. For example, reticle baseplate frontside 407 and reticle backside 409 can be facing perpendicularly away from top stage surface 202 and clamp frontside 302.

[0050] As shown in FIG. 5, reticle exchange apparatus 100 can include reticle exchange area 410, which is the cross-sectional area between clamp 300, reticle 408, reticle baseplate 406, and reticle handler arm 404 during a reticle exchange process.

[0051] In some embodiments, as shown in FIG. 4, reticle handler arms 404 can be arranged symmetrically about reticle handler 402. For example, reticle handler arms 404 can be spaced from each other by about 90 degrees, 120 degrees, or 180 degrees. In some embodiments, reticle handler arms 404 can be arranged asymmetrically about reticle handler 402. For example, two reticle handler arms 404 can be spaced from each other by about 135 degrees, while another two reticle handler arms 404 can be spaced from each other by about 90 degrees.

[0052] In one example, during a reticle exchange process, reticle handler arm 404 of reticle handler 402 positions reticle 408 on reticle baseplate 406 towards clamp 300 in reticle exchange area 410. As described above, a reticle handoff from reticle handler 402 to clamp 300 includes an unknown reticle position offset, which includes a reticle vertical distance offset (i.e., Z-direction offset) and a reticle tilt offset (i.e., Rx offset and Ry offset). Tilt or excessive non-alignment between clamp 300 and reticle 408 can be a source of particle generation and can damage reticle 408 or clamp 300 over time. Reticle backside 409 and clamp frontside 302 should be in coplanar alignment for a final handoff. Despite calibration, variations still exist due to reticle mechanical and positioning tolerances, which can lead to high comer impacts and unpredictable first contact points between clamp 300 and reticle 408.

[0053] In one example, the reticle exchange process can involve lowering reticle stage 200 with clamp 300, which starts far away from reticle handler 402, as close to reticle 408 as possible until clamp 300 contacts reticle 408 to account for all possible offsets and / or tilts. During a reticle exchange process, reticle stage 200 with clamp 300 can be adjusted in a multi-stage movement.

[0054] FIGS. 6A, 6B, and 6C show a partial schematic illustration of a reticle exchange apparatus in an approach configuration, first contact configuration, and full contact configuration, respectively, according to some embodiments.

[0055] As shown in FIGS. 6A through 6C, reticle exchange apparatus 100 can include clamp 300, reticle 408, and reticle baseplate 406. The multi-stage movement can occur in four stages: (1) approach; (2) first contact; (3) full contact; and (4) voltage applied to clamp.

[0056] In FIG. 6A, reticle exchange apparatus 100 can be in an approach configuration 20. Clamp 300 can be adjusted in a substantially vertical direction (i.e., Z-direction) toward reticle backside 409. Inapproach configuration 20, clamp 300 is turned off (i.e., no applied voltage) and reticle handler 402 deactivates the vertical direction (i.e., Z-direction) and tilt (i.e., Rx and Ry, rotation about X-direction and rotation about Y -direction, respectively) servo motors (not shown) of reticle handler arm 404 in reticle exchange area 410.

[0057] In FIG. 6B, reticle exchange apparatus 100 can be in a first contact configuration 30. Clamp 300 can be adjusted in a substantially vertical direction (i.e., Z-direction) toward reticle backside 409 until clamp 300 makes contact with reticle backside 409. In first contact configuration 30, clamp 300 is turned off and clamp 300 makes contact with reticle backside 409, for example, a comer of reticle 408, and then rotates or tilts about the contact (i.e., Rx and Ry).

[0058] In FIG. 6C, reticle exchange apparatus 100 can be in a full contact configuration 40. Clamp 300 can be rotationally adjusted about the contact (i.e., Rx and Ry) toward reticle backside 409 until clamp 300 makes full contact with reticle backside 409. In full contact configuration 40, clamp 300 is turned off and clamp 300 makes full contact with reticle backside 409, for example, all four comers of reticle 408, and is coplanar with reticle backside 409.

[0059] In some embodiments, in full contact configuration 40, clamp 300 makes contact with all four comers of reticle 408 and continues to move in a substantially vertical direction (i.e., Z-direction) until a mechanical force of at least 5 N is achieved.

[0060] In one aspect, with clamp frontside 302 and reticle backside 409 aligned and coplanar, clamp 300 is turned on (i.e., a voltage is applied to clamp 300) and reticle 408 is held in a fixed plane on clamp 300.

[0061] In some embodiments, as shown in FIG. 5, reticle exchange apparatus 100 can include clamp controller 360. Clamp controller 360 can be coupled to clamp 300 and be configured to control a position of clamp 300. For example, clamp controller 360 can be configured to control reticle stage 200 to allow compliant movement of clamp 300.

[0062] In some embodiments, clamp controller 360 can be coupled to servo motors or servo actuators (i.e., X-direction, Y-direction, Z-direction, Rx, Ry, Rz) of reticle stage 200 and / or clamp 300. For example, clamp controller 360 can control translations of reticle stage 200 with clamp 300 along an x- axis, y-axis, and z-axis (i.e., X-direction, Y-direction, Z-direction) and rotations about the x-axis, y- axis, and z-axis (i.e., Rx, Ry, Rz), where the x-axis, y-axis, and z-axis are orthogonal coordinates.

[0063] Exemplary Reticle Gripper Apparatuses

[0064] Reticles are critical and sensitive components for imparting patterns on substrates. A reticle handler may be used to move and position multiple reticles for scanning and / or patterning operations in a lithographic apparatus. Increased throughput of the lithographic apparatus may result in higher acceleration of movable parts such as stages, which may result in an increase of disturbance forces. A gripper configured to hold a reticle may be provided with flexures to isolate the reticle from disturbance forces. For Reticle transfers from reticle handler to reticle stage a high stiffness in vertical directionmay be desired. However, for disturbance force isolation a low stiffness may be desired, resulting in conflicting requirements.

[0065] In an aspect, a gripper is configured to support an item in an exposure apparatus. The gripper comprising: a magnetorheological material, and a magnet configured to generate a magnetic field, wherein the magnetorheological material is configured to be transitionable between a high stiffness state and a low stiffness state in response to the magnetic field, wherein the magnet is arranged to transition the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and to transition the magnetorheological material to the low stiffness state when the gripper is away from the loading position. The gripper may thereby isolate the reticle from disturbance forces, while for reticle transfers from reticle handler to reticle stage or vice versa a high stiffness in vertical direction may be provided.

[0066] In an embodiment, the magnet comprises a permanent magnet providing a defined magnetic field strength. The magnetic field may be applied to the magnetorheological material by moving the magnet proximate to the magnetorheological material, or vice versa.

[0067] In an embodiment, the permanent magnet is stationary at the loading position and configured to generate the magnetic field to bring the magnetorheological material into high stiffness state at the loading position. As the gripper moves to the loading position, the magnetic field may be applied to alter the state of the magnetorheological material.

[0068] In an embodiment, the magnet comprises an electromagnet enabling to determine a magnitude of the magnetic field by modulation of the coil excitation current.

[0069] The electromagnet may be movable upon movement of the gripper providing a defined position of the magnet in respect of the magnetorheological material.

[0070] The gripper may comprise a controller configured to control a coil excitation current of the electromagnet as a function of a position of the gripper, providing a defined relation between magnetic field strength and position, thus between the state of the magnetorheological material and the position of the gripper.

[0071] The controller may comprise a look up table configured to determine a magnitude of the coil excitation current as a function of a position of the gripper. The look up table may provide a defined relation between position and magnetic field strength.

[0072] The controller may be configured to generate a setpoint of the magnitude of the coil excitation current as a function of a position of the gripper.

[0073] In an embodiment, the gripper comprises a reticle gripper configured to grip a reticle.

[0074] In an embodiment, the gripper comprises a substrate gripper configured to grip a substrate.

[0075] In an aspect, a reticle exchange device is provided comprising the gripper

[0076] In an embodiment, the reticle exchange device further comprises a turret configured to move the reticle between a reticle stage and a reticle handler while the reticle is supported by the gripper; andwherein the gripper is configured to bring the magnetorheological material to the high stiffness state during an exchange of the reticle from the turret to the reticle stage.

[0077] In an aspect, an exposure apparatus is provided comprising the gripper according to any one of the above embodiments or the reticle exchange device.

[0078] In an aspect, a method of supporting an item in an exposure apparatus is provided, the method comprising supporting the item by a gripper comprising: a magnetorheological material, and a magnet configured to generate a magnetic field. The method comprises transitioning the magnetorheological material between a high stiffness state and a low stiffness state in response to the magnetic field, comprising transitioning by the magnet the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and transitioning the magnetorheological material to the low stiffness state when the gripper is away from the loading position. With the method according to an aspect, the same or similar advantages and effects may be provided as with the gripper according to an aspect. Further, the same or similar embodiments may be provided, providing the same or similar effects as described with reference to the gripper according to an aspect.

[0079] Figure 7A depicts a schematic illustration of a reticle gripper 404 in a reticle exchange area, according to some embodiments. Reticle handler 402, also referred to a rapid exchange device (RED) turret 402, can include a reticle handler arm 404. In some embodiments, reticle handler arm 404 may be referred to herein as a gripper, such as a rapid exchange device (RED) gripper. Reticle handler arm 404 can include reticle baseplate 406 as indicated in Figure 7B. Reticle baseplate 406 can be configured to hold an object, for example, reticle 408 as likewise depicted in Figure 7B. Figure 7A depicts a top view of the reticle gripper while Figure 7B depicts a side view of the reticle gripper. The reticle gripper may be configured to hold a reticle. In figure 7A, the Rapid Exchange Device, RED, has positioned the reticle gripper to be below the reticle stage 200. As seen in Figure 7B, the reticle gripper holds a reticle in a position below the reticle stage for exchange of the reticle from the reticle gripper to the reticle stage 200 or vice versa from the reticle stage to the reticle gripper. Figure 7B further depicts a rotatable part of the rapid exchange device, which is rotatable in respect of a rapid exchange device turret 402, about a vertical axis or rotation.

[0080] As seen in Figure 7B, the reticle gripper further comprises a magnetorheological element 700 comprising a magnetorheological material. The magnetorheological material is to be understood as a material which is able to transition between a high stiffness state and a low stiffness state in response to the magnetic field. For example, in the presence of a magnetic field, the magnetorheological material exhibits a high stiffness state while in the absence of a magnetic field, or in the presence of a lower field strength of the magnetic field, the magnetorheological material exhibits a low stiffness state. In the high stiffness state, the magnetorheological material exhibits a high mechanical stiffness. In the low stiffness state, the magnetorheological material exhibits a low mechanical stiffness.

[0081] In the present embodiment, the magnetorheological element interconnects a static part of the gripper and a dynamic part of the gripper. The static part of the gripper is connected to the rotatable partof the Rapid Exchange Device. The dynamic part of the gripper is connected to the reticle. In a high stiffness state, the magnetorheological element interconnects the dynamic part of the gripper and the static part of the gripper at a high stiffness. In the low stiffness state, the magnetorheological element interconnects the dynamic part of the gripper and the static part of the gripper at a low stiffness.

[0082] In the present embodiment, the reticle gripper comprises a single magnetorheological element 700. Alternatively, the reticle gripper may comprise plural magnetorheological elements, e.g. three magnetorheological elements arranged in a horizontal plane.

[0083] The reticle gripper further comprises a magnet which may be configured to generate a magnetic field. In case the magnetorheological material is exposed to the magnetic field generated by the magnet, the magnetorheological material may be in one of the high stiffness state and the low stiffness state. In case the magnetorheological material is not exposed to the magnetic field generated by the magnet, the magnetorheological material may be in the other one of the high stiffness state and the low stiffness state.

[0084] In an embodiment, the magnetorheological material stiffens when subject to the magnetic field. Accordingly, in such embodiment, in case the magnetorheological material is exposed to the magnetic field generated by the magnet, the magnetorheological material may be in the high stiffness state, and in case the magnetorheological material is not exposed to the magnetic field generated by the magnet, the magnetorheological material may be in the low stiffness state. The gripper may be configured to control an exposure of the magnetorheological material to the magnetic field so as to enable to transition between the high stiffness state of the magnetorheological material and the low stiffness state of the magnetorheological material, as described further below.

[0085] Figure 8A depicts a schematic illustration of the reticle gripper 404 as described above with reference to Figures 7A and 7B, which reticle gripper has rotated away from the reticle exchange area ,. Similarly to Figures 7A and 7B, respectively, Figure 8A depicts atop view of the reticle gripper while Figure 8B depicts a side view of the reticle gripper. In Figure 8A, the Rapid Exchange Device, RED, has positioned the reticle gripper to be rotated about the vertical axis or rotation, so as to rotate the reticle away from the reticle stage 200. As seen in Figure 8B, the reticle gripper holds a reticle in a position rotated away from the reticle stage. Likewise to Figure 7B, Figure 8B further depicts the rotatable part of the rapid exchange device, which is rotatable in respect of the rapid exchange device turret, about the vertical axis or rotation, the magnetorheological element 700 comprising the magnetorheological material, and the magnet 702 that is configured to generate the magnetic field.

[0086] In an embodiment, the reticle gripper is configured to control an exposure of the magnetorheological material to the magnetic field, as follows: In the embodiment as described with reference to Figures 7A - 7B and 8A - 8B, the magnet is stationary, i.e. in the present embodiment the magnet is connected to the turret of the rapid exchange device. The magnetorheological material on the other hand is connected to the movable part of the reticle gripper, so as to move as the reticle gripper moves. More specifically, in the present embodiment, the magnet is arranged to expose themagnetorheological material to the magnetic field as the reticle gripper is at the reticle exchange position as depicted in Figure 7A and 7B, while the magnetorheological material is remote from the magnet as the rapid exchange device is rotated away from the reticle exchange position. As seen in Figure 8A, the magnetorheological element is remote from the magnet 702 at the reticle exchange position, so as to be exposed to the magnetic field of the magnet at a low extent. Contrarily, in the position of the reticle gripper as depicted in Figure 7A, the magnetorheological element is proximate to the magnet 702 at the reticle exchange position, so as to be exposed to the magnetic field of the magnet at a high extent.

[0087] Accordingly, in the reticle exchange position the magnetorheological material is in the high stiffness state due to the exposure to the magnetic field, while away from the reticle exchange position, the magnetorheological material is in the low stiffness state. As a result, at the reticle exchange position, the magnetorheological material provides a high stiffness enabling a high positioning accuracy of the reticle upon loading the reticle on the reticle stage or unloading the reticle from the reticle stage. The high stiffness at loading and / or unloading enables a highly accurate loading and / or unloading of the reticle at the reticle stage. On the other hand, away from the reticle exchange position, the magnetorheological material provides a low stiffness enabling a high extent of vibration isolation to isolate the reticle from vibrations to which the reticle gripper may be subject.

[0088] In the embodiment described with reference to Figures 7A, 7B, 8A and 8B, the magnet may be a permanent magnet, i.e. comprise material having permanent magnetic properties. Exposure of the magnetorheological material to the magnetic field may be provided in that the magnetorheological material and the magnet are movable in respect of each other. For example, in the described embodiment, the permanent magnet is stationary at the reticle exchange position and configured to generate the magnetic field to bring the magnetorheological material into high stiffness state at the reticle exchange position, thereby enabling to transition the magnetorheological material to the high stiffness state at the reticle exchange position, while transitioning to the low stiffness state as the reticle gripper moves away from the reticle exchange position. The transition between the states of the magnetorheological material may accordingly be provided without requiring an active control of the magnetic field.

[0089] An alternative embodiment is depicted in Figures 9A, 9B, 10A and 10B. In the alternative embodiment, the magnet comprises an electromagnet. Figure 9A depicts a schematic illustration of a reticle gripper 404 in a reticle exchange area 410, according to some embodiments. Figure 9A depicts a top view of the reticle gripper while Figure 9B depicts a side view of the reticle gripper. The reticle gripper may be configured to hold a reticle. In figure 9A, the Rapid Exchange Device, RED, has positioned the reticle gripper to be below the reticle stage 200. As seen in Figure 9B, the reticle gripper holds a reticle in a position below the reticle stage for exchange of the reticle from the reticle gripper to the reticle stage or vice versa from the reticle stage to the reticle gripper. Figure 9B further depicts arotatable part of the rapid exchange device, which is rotatable in respect of a rapid exchange device turret, about a vertical axis or rotation.

[0090] As seen in Figure 9B, the reticle gripper further comprises a magnetorheological element 900 comprising a magnetorheological material. The magnetorheological material is to be understood as a material which is able to transition between a high stiffness state and a low stiffness state in response to the magnetic field. For example, in the presence of a magnetic field, the magnetorheological material exhibits a high stiffness state while in the absence of a magnetic field, or in the presence of a lower field strength of the magnetic field, the magnetorheological material exhibits a low stiffness state. In the high stiffness state, the magnetorheological material exhibits a high mechanical stiffness. In the low stiffness state, the magnetorheological material exhibits a low mechanical stiffness.

[0091] In the present embodiment, the magnetorheological element interconnects a static part of the gripper and a dynamic part of the gripper. The static part of the gripper is connected to the rotatable part of the Rapid Exchange Device. The dynamic part of the gripper is connected to the reticle. In a high stiffness state, the magnetorheological element interconnects the dynamic part of the gripper and the static part of the gripper at a high stiffness. In the low stiffness state, the magnetorheological element interconnects the dynamic part of the gripper and the static part of the gripper at a low stiffness.

[0092] The reticle gripper comprises a single magnetorheological element 700. Alternatively, the reticle gripper may comprise plural magnetorheological elements, e.g. three magnetorheological elements arranged in a horizontal plane.

[0093] The reticle gripper further comprises a magnet which may be configured to generate a magnetic field. In case the magnetorheological material is exposed to the magnetic field generated by the magnet, the magnetorheological material may be in one of the high stiffness state and the low stiffness state. In case the magnetorheological material is not exposed to the magnetic field generated by the magnet, the magnetorheological material may be in the other one of the high stiffness state and the low stiffness state.

[0094] In an embodiment, the magnetorheological material stiffens when subject to the magnetic field. Accordingly, in such embodiment, in case the magnetorheological material is exposed to the magnetic field generated by the magnet, the magnetorheological material may be in the high stiffness state, and in case the magnetorheological material is not exposed to the magnetic field generated by the magnet, the magnetorheological material may be in the low stiffness state. The gripper may be configured to control an exposure of the magnetorheological material to the magnetic field so as to enable to transition between the high stiffness state of the magnetorheological material and the low stiffness state of the magnetorheological material, as described further below.

[0095] Figure 10A depicts a schematic illustration of the reticle gripper 404, as described above with reference to Figures 9A and 9B, which has rotated away from the reticle exchange area. Similarly to Figures 9A and 9B, respectively, Figure 10A depicts atop view of the reticle gripper while Figure 10B depicts a side view of the reticle gripper. In Figure 10A, the Rapid Exchange Device, RED, haspositioned the reticle gripper to be rotated about the vertical axis or rotation, so as to rotate the reticle away from the reticle stage 200. As seen in Figure 10B, the reticle gripper holds a reticle in a position rotated away from the reticle stage. Likewise to Figure 9B, Figure 10B further depicts the rotatable part of the rapid exchange device, which is rotatable in respect of the rapid exchange device turret, about the vertical axis or rotation, the magnetorheological element 900 comprising the magnetorheological material, and the magnet 902 that is configured to generate the magnetic field.

[0096] In an embodiment, the reticle gripper is configured to control an exposure of the magnetorheological material to the magnetic field, as follows: In the embodiment as described with reference to Figures 9A - 9B and 10A - 10B, the magnet is movable with the gripper, i.e. in the present embodiment the magnet is connected to the movable part of the gripper of the rapid exchange device. In the present embodiment, the magnet comprises an electromagnet 902 which is arranged to expose the magnetorheological material to the magnetic field. The gripper comprises a controller 904 which is configured to control a coil excitation current of the electromagnet as a function of a position of the gripper.

[0097] For example, the controller may be configured to control a magnitude of the coil excitation current as the gripper is at the reticle exchange position, providing a high magnitude of the coil excitation current causing the magnetorheological material to be in the high stiffness state due to the exposure to the magnetic field. The controller may be configured to decrease the magnitude of the coil excitation current while the gripper is away from the reticle exchange position, providing that the magnetorheological material is in the low stiffness state. As a result, at the reticle exchange position, the magnetorheological material provides a high stiffness enabling a high positioning accuracy of the reticle upon loading the reticle on the reticle stage or unloading the reticle from the reticle stage. The high stiffness at loading and / or unloading enables a highly accurate loading and / or unloading of the reticle at the reticle stage. On the other hand, away from the reticle exchange position, the magnetorheological material provides a low stiffness enabling a high extent of vibration isolation to isolate the reticle from vibrations to which the reticle gripper may be subject. The magnetorheological material may also provides tunable damping and hence may improve disturbance force isolation in the system.

[0098] In the embodiment described with reference to Figures 9A, 9B, 10A and 10B, the magnet may be a permanent magnet, i.e. comprise material having permanent magnetic properties. Exposure of the magnetorheological material to the magnetic field may be provided in that the magnetorheological material and the magnet are movable in respect of each other. For example, in the described embodiment, the permanent magnet is stationary at the reticle exchange position and configured to generate the magnetic field to bring the magnetorheological material into high stiffness state at the reticle exchange position, thereby enabling to transition the magnetorheological material to the high stiffness state at the reticle exchange position, while transitioning to the low stiffness state as the reticle gripper moves away from the reticle exchange position. The transition between the states of themagnetorheological material may accordingly be provided without requiring an active control of the magnetic field.

[0099] In a practical embodiment, the controller may determine the magnitude of the coil excitation current on the basis of the position of the movable part of the gripper, making use of a look up table, to establish a defined relation between the position and the magnetic field to which the magnetorheological material is subject.

[0100] As an alternative to the look up table, the controller may be configured to generate a setpoint of the magnitude of the coil excitation current as a function of a position of the gripper. For example, a the reticle exchange position, the setpoint of the magnitude of the coil excitation current may be high, while away from the reticle exchange position, the setpoint of the magnitude of the coil excitation current may be low.

[0101] In the above embodiments, the gripper is comprised in a reticle exchange device. In other embodiments, the gripper may be comprised in an exposure apparatus, such as a lithographic apparatus. For example, the gripper may be a substrate gripper configured to support a substrate, such as a wafer. The reticle exchange device may be a rotating device as described in the example above. In other embodiments, the reticle change device may be a robot with multiple degrees of freedom motion. The reticle exchange device may comprise multiple grippers. Further embodiments of the gripper may include any device that supports an item in the exposure apparatus. The magnetorheological material and the magnet may not only be used in a gripper of the exposure apparatus. Rather, the magnetorheological material and the magnet may be used in the exposure apparatus to provide a controllable stiffness for any element, such as a sensor, an actuator, a support, etc. For example, the element may comprise an alignment sensor of the exposure apparatus, hence enabling to dynamically or statically change the damping on the alignment sensor of the exposure apparatus.

[0102] Accordingly, the exposure apparatus may comprising the gripper as described above or the reticle exchange device as described above.

[0103] Although specific reference may be made in this text to a “reticle,” it should be understood that this is just one example of a patterning device and that the embodiments described herein may be applicable to any type of patterning device. Additionally, the embodiments described herein may be used to provide safety support for any object to ensure a clamping failure does not cause the object to fall and damage either itself or other equipment.

[0104] Various embodiments of the present systems and methods are disclosed in the subsequent list of numbered clauses. In the following, further features, characteristics, and exemplary technical solutions of the present disclosure will be described in terms of clauses that may be optionally claimed in any combination:1. A gripper configured to support an item in an exposure apparatus, the gripper comprising: a magnetorheological material, and a magnet configured to generate a magnetic field,wherein the magnetorheological material is configured to be transitionable between a high stiffness state and a low stiffness state in response to the magnetic field, wherein the magnet is arranged to transition the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and to transition the magnetorheological material to the low stiffness state when the gripper is away from the loading position.2. The gripper according to clause 1, wherein the magnet comprises a permanent magnet3. The gripper according to clause 1 or 2, wherein the permanent magnet is stationary at the loading position and configured to generate the magnetic field to bring the magnetorheological material into high stiffness state at the loading position.4. The gripper according to clause 1, wherein the magnet comprises an electromagnet.5. The gripper according to clause 4, wherein the electromagnet is movable upon movement of the gripper.6. The gripper according to clause 4 or 5, wherein the gripper comprises a controller configured to control a coil excitation current of the electromagnet as a function of a position of the gripper.7. The gripper according to clause 6, wherein the controller comprises a look up table configured to determine a magnitude of the coil excitation current as a function of a position of the gripper.8. The gripper according to clause 6, wherein the controller is configured to generate a setpoint of the magnitude of the coil excitation current as a function of a position of the gripper.9. The gripper according to any one of the preceding clauses, wherein the gripper comprises a reticle gripper configured to grip a reticle.10. The gripper according to any one of clauses 1 - 8, wherein the gripper comprises a substrate gripper configured to grip a substrate.11. A reticle exchange device comprising the gripper according to any one of clauses 1 - 10.12. The reticle exchange device according to clause 11, further comprising a turret configured to move the reticle between a reticle stage and a reticle handler while the reticle is supported by the gripper; and wherein the gripper is configured to bring the magnetorheological material to the high stiffness state during an exchange of the reticle from the turret to the reticle stage.13. An exposure apparatus comprising the gripper according to any one of clauses 1 - 10 or the reticle exchange device according to clause 11 or 12.14. A method of supporting an item in an exposure apparatus using a gripper, wherein the gripper includes a magnetorheological material and a magnet configured to generate a magnetic field, the method comprising: transitioning the magnetorheological material between a high stiffness state and a low stiffness state in response to the magnetic field; andtransitioning by the magnet the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and transitioning the magnetorheological material to the low stiffness state when the gripper is away from the loading position.

[0105] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, LCDs, thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion”, respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track unit (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology unit and / or an inspection unit. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0106] Although specific reference may have been made above to the use of embodiments of the disclosure in the context of optical lithography, it will be appreciated that the disclosure can be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device can be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

[0107] It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present disclosure is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

[0108] The term “substrate” as used herein describes a material onto which material layers are added. In some embodiments, the substrate itself can be patterned and materials added on top of it may also be patterned, or may remain without patterning.

[0109] Although specific reference can be made in this text to the use of the apparatus and / or system according to the disclosure in the manufacture of ICs, it should be explicitly understood that such an apparatus and / or system has many other possible applications. For example, it can be employed in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, LCD panels, thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “reticle,” “wafer,” or “die” in this text should be considered as being replaced by the more general terms “mask,” “substrate,” and “target portion,” respectively.

[0110] While specific embodiments of the disclosure have been described above, it will be appreciated that the disclosure can be practiced otherwise than as described. The description is not intended to limit the disclosure.[oni] It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.

[0112] The present disclosure has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0113] The foregoing description of the specific embodiments will so fully reveal the general nature of the disclosure that others can, by applying knowledge within the skill of the art, readily modify and / or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.

[0114] The breadth and scope of the present disclosure should not be limited by any of the abovedescribed exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

CLAIMS1. A gripper configured to support an item in an exposure apparatus, the gripper comprising: a magnetorheological material, and a magnet configured to generate a magnetic field, wherein the magnetorheological material is configured to be transitionable between a high stiffness state and a low stiffness state in response to the magnetic field, wherein the magnet is arranged to transition the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and to transition the magnetorheological material to the low stiffness state when the gripper is away from the loading position.

2. The gripper according to claim 1, wherein the magnet comprises a permanent magnet3. The gripper according to claim 1, wherein the permanent magnet is stationary at the loading position and configured to generate the magnetic field to bring the magnetorheological material into high stiffness state at the loading position.

4. The gripper according to claim 1, wherein the magnet comprises an electromagnet.

5. The gripper according to claim 4, wherein the electromagnet is movable upon movement of the gripper.

6. The gripper according to claim 4, wherein the gripper comprises a controller configured to control a coil excitation current of the electromagnet as a function of a position of the gripper.

7. The gripper according to claim 6, wherein the controller comprises a look up table configured to determine a magnitude of the coil excitation current as a function of a position of the gripper.

8. The gripper according to claim 6, wherein the controller is configured to generate a setpoint of the magnitude of the coil excitation current as a function of a position of the gripper.

9. The gripper according to claim 1, wherein the gripper comprises a reticle gripper configured to grip a reticle.

10. The gripper according to claim 1, wherein the gripper comprises a substrate gripper configured to grip a substrate.

11. A reticle exchange device having a gripper configured to support an item in an exposure apparatus, the gripper comprising: a magnetorheological material, and a magnet configured to generate a magnetic field, wherein the magnetorheological material is configured to be transitionable between a high stiffness state and a low stiffness state in response to the magnetic field, wherein the magnet is arranged to transition the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and to transition the magnetorheological material to the low stiffness state when the gripper is away from the loading position.

12. The reticle exchange device according to claim 11, further comprising a turret configured to move the reticle between a reticle stage and a reticle handler while the reticle is supported by the gripper; and wherein the gripper is configured to bring the magnetorheological material to the high stiffness state during an exchange of the reticle from the turret to the reticle stage.

13. A method of supporting an item in an exposure apparatus using a gripper, wherein the gripper includes a magnetorheological material and a magnet configured to generate a magnetic field, the method comprising: transitioning the magnetorheological material between a high stiffness state and a low stiffness state in response to the magnetic field; and transitioning by the magnet the magnetorheological material to the high stiffness state when the gripper is in a loading position for loading the item and transitioning the magnetorheological material to the low stiffness state when the gripper is away from the loading position.

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