阅读说明：本技术 光刻设备和用于电机温度控制的方法 (Lithographic apparatus and method for temperature control of a motor ) 是由 I·查韦斯 M·A·基耶达 R·I·麦肯齐 于 2020-03-12 设计创作，主要内容包括：一种光刻设备,包括照射系统、投影系统、平台、电机、热控制系统和控制器。所述照射系统照射图案形成装置的图案。所述投影系统将所述图案的图像投影至衬底上。所述平台支撑所述图案形成装置或所述衬底。所述电机移动所述平台。所述热控制系统调节所述电机的温度。所述控制器在所述电机的空转期间控制所述电机的温度,使得所述电机在所述空转期间的最高温度与最低温度之间的差减小。(A lithographic apparatus includes an illumination system, a projection system, a stage, a motor, a thermal control system, and a controller. The illumination system illuminates a pattern of a patterning device. The projection system projects an image of the pattern onto a substrate. The stage supports the patterning device or the substrate. The motor moves the platform. The thermal control system regulates a temperature of the motor. The controller controls the temperature of the motor during idling of the motor such that a difference between a highest temperature and a lowest temperature of the motor during the idling is reduced.)

1. A lithographic apparatus, the lithographic apparatus comprising:

an illumination system configured to illuminate a pattern of a patterning device;

a projection system configured to project an image of the pattern onto a substrate;

a stage configured to support the patterning device or the substrate;

a motor configured to move the platform;

a thermal control system configured to regulate a temperature of the electric machine; and

a controller configured to control a temperature of the motor during idling of the motor such that a difference between a highest temperature and a lowest temperature of the motor during idling is reduced.

2. The lithographic apparatus of claim 1, further comprising a temperature sensor disposed on or near the motor, the temperature sensor configured to generate motor temperature information, wherein the controller is further configured to:

receiving the motor temperature information;

determining a temperature adjustment command based on the motor temperature information; and

sending the temperature adjustment command to the thermal control system to maintain a temperature of the electric machine during idle.

3. The lithographic apparatus of claim 1, wherein the thermal control system comprises a conduit system thermally coupled to a motor, and the conduit system is configured to circulate a heat transfer fluid to and from the motor.

4. The lithographic apparatus of claim 3, wherein the heat transfer fluid comprises water.

5. The lithographic apparatus of claim 3, wherein:

the conduit system comprises one or more valves; and is

The controller is further configured to actuate the one or more valves to reduce or stop circulation of the heat transfer fluid to maintain the temperature of the motor during idle.

6. The lithographic apparatus of claim 1, wherein:

the controller is further configured to supply an AC current to the motor to maintain a temperature of the motor during idle; and is

The AC current has a frequency that causes the motor to freewheel.

7. The lithographic apparatus of claim 1, wherein:

the motor includes a first coil and a second coil electrically independent from the first coil;

the controller is further configured to supply a first current to the first coil and a second current to the second coil to maintain a temperature of the motor during idling; and is

The first and second currents generate opposing forces causing the motor to freewheel.

8. The lithographic apparatus of claim 1, further comprising a heating element disposed on or near the motor, wherein the controller is further configured to allow the heating element to heat the motor, thereby maintaining a temperature of the motor during idle.

9. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by a controller, cause the controller to perform operations comprising:

starting idling of a motor of a stage in the lithographic apparatus;

sending a temperature adjustment instruction to a thermal adjustment component of the lithographic apparatus; and

adjusting a temperature of the motor during idling using the thermal adjustment component such that a difference between a highest temperature and a lowest temperature of the motor during idling is reduced.

10. The non-transitory computer-readable medium of claim 9, wherein the operations further comprise:

receiving motor temperature information generated by a temperature sensor disposed on or near the motor; and

determining the temperature adjustment command based on the motor temperature information.

11. The non-transitory computer-readable medium of claim 10, wherein:

the lithographic apparatus comprises a thermal control system comprising a conduit system configured to circulate a heat transfer fluid to and from the motor, the conduit system comprising one or more valves, and the adjusting comprises actuating the one or more valves to reduce or stop circulation of the heat transfer fluid to maintain the temperature of the motor during idle; and/or

The lithographic apparatus comprises a heating element disposed on or near the motor, and the adjusting comprises heating the motor using the heating element to maintain a temperature of the motor during idling.

12. The non-transitory computer-readable medium of claim 9, wherein:

the adjusting comprises supplying an AC current to the motor to maintain a temperature of the motor during idling, the AC current having a frequency such that the motor idles; and/or

The motor includes a first coil and a second coil, and the adjusting includes supplying a first current to the first coil and a second current to the second coil to maintain a temperature of the motor during freewheeling, the first current and the second current generating opposing forces such that the motor freewheels.

13. A system for maintaining a temperature of an actuator during an idle period of the actuator, the system comprising:

a table configured to support an article;

an actuator configured to move the stage;

a thermal control system configured to regulate a temperature of the actuator; and

a controller configured to control a temperature of the actuator during the idle such that a difference between a highest temperature and a lowest temperature of the actuator during the idle is reduced.

14. The system of claim 13, further comprising a temperature sensor disposed on or near the actuator, the temperature sensor configured to generate actuator temperature information, wherein the controller is further configured to:

receiving the actuator temperature information;

determining a temperature adjustment command based on the actuator temperature information; and

sending the temperature adjustment command to the thermal control system to maintain the temperature of the actuator during idle.

15. The system of claim 13, wherein:

the thermal control system comprises a conduit system thermally coupled to the actuator and configured to circulate a heat transfer fluid to and from the actuator, the conduit system comprising one or more valves, and the controller is further configured to actuate the one or more valves to reduce or stop circulation of the heat transfer fluid to maintain the temperature of the actuator during idle; and/or

The system includes a heating element disposed on or near the actuator, and the controller is further configured to allow the heating element to heat the actuator to maintain a temperature of the actuator during idle.

16. The system of claim 13, wherein:

the controller is further configured to supply an AC current to the actuator to maintain a temperature of the actuator during idling, the AC current having a frequency that causes the actuator to idle; and/or

The actuator includes a first coil and a second coil electrically independent of the first coil, and the controller is further configured to supply a first current to the first coil and a second current to the second coil to maintain a temperature of the actuator during freewheeling, the first current and the second current generating opposing forces such that the actuator freewheels.

Technical Field

The present disclosure relates to motors and thermal control, e.g., maintaining the temperature of a motor for thermal control of an actuation stage in a lithographic apparatus.

Background

A lithographic apparatus is a machine that is configured to apply a desired pattern onto a substrate. 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., mask, reticle) onto a layer of radiation-sensitive material (resist) disposed on a substrate.

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 that can be formed on the substrate. A lithographic apparatus using Extreme Ultraviolet (EUV) radiation having a wavelength in the range of 4nm to 20nm (e.g. 6.7nm or 13.5nm) may be used to form smaller features on a substrate than a lithographic apparatus using radiation having a wavelength of 193nm, for example.

Advances in lithography technology have facilitated improvements in lithography tool efficiency. Some areas of efficiency include time investment, mass production, and operating costs, among others. It is desirable to address problems or obstacles that hinder further efficiency improvements of lithographic tools.

During a reticle exchange process, reticle handoff or transfer from a reticle handler to a chuck of a reticle stage may result in large variations (e.g., thermal cycling) in the temperature of a motor responsible for moving the reticle stage. Thermal cycling can accelerate premature failure of the motor. There is a need to prevent premature failure of the motor for preventing costly machine downtime and maintenance.

Disclosure of Invention

In some embodiments, a lithographic apparatus includes an illumination system, a projection system, a stage, a motor, a thermal control system, and a controller. The illumination system is configured to illuminate a pattern of a patterning device. The projection system is configured to project an image of the pattern onto a substrate. The stage is configured to support the patterning device or the substrate. The motor is configured to move the platform. The thermal control system is configured to regulate a temperature of the electric machine. The controller is configured to control a temperature of the motor during idling of the motor such that a difference between a highest temperature and a lowest temperature of the motor during the idling is reduced.

In some embodiments, a method of regulating temperature during idling of a motor of a stage in a lithographic apparatus comprises: initiating the idling of the motor of the stage in the lithographic apparatus; sending motor temperature information to a controller during the idle; determining a temperature adjustment command based on the motor temperature information; sending the temperature adjustment instruction to a thermal adjustment component of the lithographic apparatus; and adjusting a temperature of the motor during the idling using the thermal adjustment component such that a difference between a highest temperature and a lowest temperature of the motor during the idling is reduced.

In some embodiments, a non-transitory computer-readable medium has instructions stored thereon, which, when executed by a controller, cause the controller to perform operations. The operations include: starting idling of a motor of a stage in the lithographic apparatus; receiving motor temperature information; determining a temperature adjustment command based on the motor temperature information; sending the temperature adjustment instruction to a thermal adjustment component of the lithographic apparatus; and adjusting a temperature of the motor during the idling using the thermal adjustment component such that a difference between a highest temperature and a lowest temperature of the motor during the idling is reduced.

Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. It should be noted that the present invention 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.

Drawings

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

FIG. 1 depicts a schematic illustration of a lithographic apparatus according to some embodiments;

fig. 2 shows a perspective schematic illustration of a portion of a reticle stage according to an example embodiment;

FIG. 3 illustrates a top plan view of the reticle stage of FIG. 2;

FIG. 4 illustrates a perspective schematic illustration of a reticle exchange tool according to some embodiments;

FIG. 5 shows a partial cross-sectional view of the reticle exchange tool of FIG. 4;

fig. 6A shows a partial schematic illustration of a reticle exchange tool in a proximity configuration in accordance with some embodiments;

fig. 6B shows a partial schematic illustration of a reticle exchange tool in a first contact configuration in accordance with some embodiments;

fig. 6C shows a partial schematic illustration of a reticle exchange tool in a full contact configuration in accordance with some embodiments;

FIG. 7 depicts a schematic view of a sub-portion of a lithographic apparatus according to some embodiments.

FIG. 8 shows a graph illustrating thermal cycling during a continuous photolithography process, according to some embodiments.

FIG. 9 depicts a schematic view of a sub-portion of a lithographic apparatus according to some embodiments.

FIG. 10 illustrates method steps for adjusting temperature during idling of a motor of a stage in a lithographic apparatus according to some embodiments.

The features and advantages of the present invention 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. In addition, in general, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout this disclosure should not be construed as being to scale.

Detailed Description

This specification discloses one or more embodiments that incorporate the features of this invention. The disclosed embodiments are merely illustrative of the invention. The scope of the invention is not limited to the disclosed embodiments. The invention is defined by the claims appended to this specification.

References in the described embodiments and this specification to "one embodiment," "an example embodiment," etc., indicate that the embodiment 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 submitted 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.

For ease of description, spatially relative terms, such as "below … …," "below … …," "lower," "above … …," "above … …," "upper," and the like, may be used herein to describe one element or feature's relationship to another element or feature illustrated in the figures. In addition to the orientations depicted in the figures, the spatially relative terms are also intended to encompass different orientations of the device in use or operation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly as well.

The term "about" as used herein indicates a value of a given amount that may vary based on the particular technique. The term "about" can indicate a value of a given quantity, e.g., within 10% to 30% of the stated value (e.g., ± 10%, ± 20% or ± 30% of the stated value), based on the particular technique.

Embodiments of the present 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); a magnetic disk storage medium; an optical storage medium; a flash memory device; electrical, optical, acoustical or other form 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 understood 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 that doing so may cause actuators or other devices to interact with the physical world. For non-transitory machine-readable media and the like, the term "non-transitory" may refer to all computer/machine-readable media, with the sole exception of transitory propagating signals.

However, before describing such embodiments in more detail, it is instructive to provide an example environment in which embodiments of the present disclosure may be implemented.

Exemplary lithography System

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.

The illumination system IL is configured to condition an EUV radiation beam B before it is incident on the patterning device MA. In addition, the illumination system IL may comprise a facet field mirror device 10 and a facet pupil mirror device 11. The facet field mirror device 10 and the facet pupil mirror device 11 together provide a desired cross-sectional shape and a desired intensity distribution to the EUV radiation beam B. The illumination system IL may also comprise other mirrors or devices in addition to the facet field mirror device 10 and the facet pupil mirror device 11, or instead of the facet field mirror device 10 and the facet pupil mirror device 11.

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

The substrate W may include a previously formed pattern. In such cases, the lithographic apparatus LA aligns an image formed by the patterned EUV radiation beam B' with a pattern previously formed on the substrate W.

A relative vacuum, i.e. a small amount of gas (e.g. hydrogen) at a pressure substantially lower than atmospheric pressure, may be provided in the radiation source SO, in the illumination system IL and/or in the projection system PS.

The radiation source SO may be a Laser Produced Plasma (LPP) source, a Discharge Produced Plasma (DPP) source, a Free Electron Laser (FEL) or any other radiation source capable of producing EUV radiation.

Exemplary reticle stage

Fig. 2 and 3 show schematic illustrations of an exemplary reticle stage 200, according to some embodiments. Reticle stage 200 may include a top stage surface 202, a bottom stage surface 204, side stage surfaces 206, and a clamp 300. In some embodiments, reticle stage 200 with clamp 300 may be implemented in a lithographic apparatus LA. For example, the reticle stage 200 may be a support structure MT in a lithographic apparatus LA. In some embodiments, the fixture 300 may be positioned on the top platform surface 202. For example, as shown in fig. 2, the clamp 300 may be positioned at the center of the top platform surface 202 with the clamp front side 302 facing vertically away from the top platform surface 202.

In some lithographic apparatus (e.g., lithographic apparatus LA), reticle stage 200 with clamp 300 may be used to hold and position reticle 408 for scanning or patterning operations. In one example, the reticle stage 200 may require a high power drive, a massive weight, and a heavy frame to support the reticle stage. In one example, the reticle stage 200 may have a large inertia and may weigh more than 500kg to push and position a reticle 408 weighing about 0.5 kg. To achieve the reciprocating motion of the reticle 408 typically found in lithographic scanning or patterning operations, acceleration and deceleration forces may be provided by linear motors driving the reticle stage 200.

In some embodiments, as shown in fig. 2 and 3, reticle stage 200 may include first encoder 212 and second encoder 214 for positioning operations. For example, the first encoder 212 and the second encoder 214 may be interferometers. First encoder 212 may be attached along a first direction (e.g., a lateral direction (i.e., the X direction)) of reticle stage 200. And a second encoder 214 may be attached along a second direction (e.g., a longitudinal direction (i.e., Y-direction)) of the reticle stage 200. In some embodiments, as shown in fig. 2 and 3, the first encoder 212 may be orthogonal to the second encoder 214.

As shown in fig. 2 and 3, reticle stage 200 may include a clamp 300. The fixture 300 is configured to hold the reticle 408 in a fixed plane on the reticle stage 200. The fixture 300 includes a fixture front side 302 and may be disposed on the top platform surface 202. In some embodiments, the gripper 300 may use mechanical, vacuum, electrostatic or other suitable gripping techniques to hold and secure the object. In some embodiments, the chuck 300 may be an electrostatic chuck, which may be configured to electrostatically chuck (i.e., hold) an object, such as reticle 408, in a vacuum environment. Due to the requirement for EUV radiation to be performed in a vacuum environment, vacuum clamps cannot be used to clamp the mask or reticle, and instead, electrostatic clamps may be used. For example, the fixture 300 may include electrodes, a resistive layer on the electrodes, a dielectric layer on the resistive layer, and protrusions protruding from the dielectric layer. In use, a voltage may be applied to the fixture 300, for example, several kV. And a current may flow through the resistive layer such that the voltage at the upper surface of the resistive layer will be approximately the same as the voltage of the electrodes and generate an electric field. In addition, coulombic forces, i.e., the attractive forces between charged particles of opposite charge polarity, will attract the object to the fixture 300 and hold the object in place. In some embodiments, the clip 300 may be a rigid material, such as a metal, dielectric, ceramic, or a combination thereof.

Exemplary reticle exchange device

Fig. 4-6 show schematic illustrations of an exemplary reticle exchange tool 100, according to some embodiments. Reticle exchange tool 100 may be configured to minimize reticle exchange time, particle generation, and contact forces or stresses from jig 300 and/or reticle 408 to reduce damage to jig 300 and reticle 408 and increase overall throughput during reticle exchange (e.g., in lithography tool LA).

As shown in fig. 4 and 5, reticle exchange tool 100 may include a reticle stage 200, a clamp 300, and an in-vacuum robot 400. The in-vacuum robot 400 may include a reticle handler 402.

In some embodiments, the reticle handler 402 may be a Rapid Exchange Device (RED) configured to rotate efficiently and minimize reticle exchange time. For example, reticle handler 402 may save time by moving multiple reticles from one location to another location substantially simultaneously rather than sequentially.

In some embodiments, as shown in fig. 4, the reticle transport 402 may include one or more reticle transport arms 404. The reticle handler arm 404 may include a reticle base plate 406. Reticle base 406 may be configured to hold an object, such as reticle 408.

In some embodiments, reticle base plate 406 may be an extreme ultraviolet (EIP) chamber for reticles. In some embodiments, reticle base plate 406 includes a reticle base plate front side 407 and reticle 408 includes a reticle back side 409.

In some embodiments, as shown in fig. 4 and 5, reticle base plate 406 may hold reticle 408 such that reticle base plate front side 407 and reticle back side 409 face top stage surface 202 and chuck front side 302, respectively. For example, reticle base plate front side 407 and reticle back side 409 may face perpendicularly away from top stage surface 202 and chuck front side 302.

As shown in fig. 5, reticle exchange tool 100 may include a reticle exchange area 410, which is a cross-sectional area between clamp 300, reticle 408, reticle base plate 406, and reticle handler arm 404 during a reticle exchange process.

In some embodiments, as shown in fig. 4, the reticle transport arm 404 may be symmetrically arranged about the reticle transport 402. For example, the reticle handler arms 404 may be spaced about 90 degrees, 120 degrees, or 180 degrees apart from each other. In some embodiments, the reticle transport arm 404 may be asymmetrically arranged with respect to the reticle transport 402. For example, two reticle handler arms 404 may be spaced apart from each other by about 135 degrees, while the other two reticle handler arms 404 may be spaced apart from each other by about 90 degrees.

In one example, during a reticle exchange process, a reticle handler arm 404 of a reticle handler 402 positions a reticle 408 on a reticle base plate 406 in a reticle exchange area 410 towards the reticle 300. As described above, reticle handoff or transfer from reticle handler 402 to gripper 300 includes unknown reticle positional offsets including reticle vertical distance offset (i.e., Z direction offset) and reticle tilt angle offset (i.e., R)_XOffset and R_YOffset). Tilt angles or excessive misalignment between the reticle 408 and the chuck 300 may be a source of particle generation and may damage the reticle 408 or the chuck 300 over time. The reticle backside 409 and the jig front side 302 should be in coplanar alignment for final handover. Regardless of the calibration, there are still variations due to reticle mechanical and positioning tolerances, which may lead to high corner effects and unpredictable first contact points between the fixture 300 and the reticle 408.

In one example, the reticle exchange process may involve lowering the reticle stage 200 with the gripper 300 as close as possible to the reticle 408, starting away from the reticle handler 402 until the gripper 300 contacts the reticle 408 to account for all possible offsets and/or tilt angles. During the reticle exchange process, the reticle stage 200 with the clamp 300 may be adjusted in a multi-stage movement.

As shown in fig. 6A-6C, reticle exchange tool 100 may include a clamp 300, a reticle 408, and a reticle base plate 406. Multiple stage movements may occur in four phases: (1) approaching; (2) a first contact; (3) fully contacting; and (4) applying a voltage to the fixture.

First, as shown in fig. 6A, reticle exchange tool 100 may assume an access configuration 20, and clamp 300 may be adjusted in a substantially vertical direction (i.e., Z-direction) toward reticle backside 409. In the proximity configuration 20, the clamp 300 is closed (i.e., no voltage applied) and the reticle transport 402 deactivates the maskVertical direction (i.e., Z direction) and tilt angle (i.e., R) of reticle handler arm 404 in reticle exchange area 410_XAnd R_YRotating around the X direction and rotating around the Y direction, respectively). Electric motor (i.e., Z, R)_XAnd R_Y) Braking, and rotation about the Z direction (i.e., R)_Z) And (5) starting.

Second, as shown in fig. 6B, reticle exchange tool 100 may assume first contact configuration 30, and clamp 300 may be adjusted in a substantially vertical direction (i.e., Z-direction) toward reticle backside 409 until clamp 300 is in contact with reticle backside 409. In the first contact configuration 30, the clamp 300 is closed and the clamp 300 is in contact with the reticle backside 409, e.g., contacts a corner portion of the reticle 408, and then rotated or tilted about the contact (i.e., R)_XAnd R_Y)。

Third, as shown in fig. 6C, reticle exchange tool 100 may assume a full contact configuration 40, and clamp 300 may rotate about the contact (i.e., R)_XAnd R_Y) Adjusted towards the reticle back side 409 until the clamp 300 is in full contact with the reticle back side 409. In the full contact configuration 40, the clamp 300 is closed and the clamp 300 is in full contact with the reticle backside 409, e.g. all four corners of the reticle 408 and coplanar with the reticle backside 409.

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

Fourth, with the chuck front side 302 and the reticle back side 409 aligned and coplanar, the chuck 300 is opened (i.e., a voltage is applied to the chuck 300) and the reticle 408 is held in a fixed plane on the chuck 300.

In some embodiments, as shown in fig. 5, reticle exchange tool 100 may include a clamp controller 360. The clamp controller 360 may be coupled to the clamp 300 and may be configured to control a position of the clamp 300. For example, the clamp controller 360 may be configured to control the reticle stage 200 to allow compliant movement of the clamp 300. In some embodiments, the clamp controller 360 may be coupled to servo motors or servo actuators (i.e., X-direction, Y-direction, Z-direction, R-direction) of the reticle stage 200 and/or the clamp 300_X、R_Y、R_Z). For example, the chuck controller 360 may control translation of and about the X, Y, and Z axes (i.e., X, Y, Z directions) of the reticle stage 200 with the chuck 300 (i.e., X, Y, Z directions)_X、R_Y、R_Z) Wherein the x-axis, y-axis, and z-axis are orthogonal coordinates.

Exemplary thermal control of an electric machine

The lithographic apparatus may have a number of moving parts (e.g., stage, wafer stage, reticle stage), many of which may be actuated by motors. Thus, the motors used to move the table and platform that support the object in the machine may be referred to as actuators. Motors used in lithographic apparatus may have many components, such as heat transfer components, to carry away heat dissipated by the motor.

FIG. 7 shows a schematic view of a subsection 700 of a lithographic apparatus according to some embodiments. In some embodiments, subsection 700 includes an electric machine 702 and a thermal control system 704. The sub-section 700 also includes a heat transfer element 708 (e.g., a cold plate). The motor 702 includes a coil 712 (e.g., as in a lorentz force motor). The number of coil elements shown is for illustration and not limitation. Thermal control system 704 includes a conduit system 714. The conduit system 714 includes a supply line 716 and a return line 718.

In some embodiments, each of the coils 712 is electrically independent of the other coils. The heat transfer element 708 is adhered to the electrical machine 702 using an adhesive (e.g., an epoxy with high thermal conductivity) for thermal coupling. Some advantages of using adhesives are lower coverage areas such as cost effectiveness and volume reduction. The heat transfer element 708 may be part of the thermal control system 704 in a permanent arrangement (e.g., welded to the conduit system 714).

In some embodiments, motor 702 is configured to move a stage (e.g., reticle stage 200 in fig. 2) in the lithographic apparatus. Thermally coupled via heat transfer element 708 allows for thermal communication between electrical machine 702 and thermal control system 704. The conduit system 714 is configured to circulate a heat transfer fluid (e.g., water) to the heat transfer element 708 and the electric machine 702, and to circulate the heat transfer fluid (e.g., water) away from the heat transfer element 708 and the electric machine 702. Thermal control system 704 is configured to regulate (e.g., adjust or maintain) a temperature of electric machine 702. When the motor generates heat during the lithographic process, a simple and cost-effective way to cool the motor is to provide continuous heat removal (e.g. continuous circulation of water) at the cooling plate. This is a solution for maintaining the motor temperature below the threshold overheat temperature. In some embodiments, the subsection 700 may include a temperature sensor (not shown) for monitoring the temperature of the motor 702.

During the lithography process, the motor may experience idle or idle cycles, wherein the motor dissipates reduced or no heat, for example when the reticle stage is idle during the reticle exchange process. Continuous circulation of the cooling fluid, while simple and cost effective, can result in a significant reduction in the motor temperature from the nominal operating temperature. Once the reticle exchange process is complete, the motor moves the reticle stage for a subsequent photolithography process to return the motor temperature to a nominal operating temperature. This thermal cycling applies a large amount of cyclic stress at interfaces where materials with different Coefficients of Thermal Expansion (CTE) meet (e.g., at the epoxy interface between the cooling plate and the electric machine).

Fig. 8 shows a graph 800 illustrating thermal cycling during a continuous photolithography process, in accordance with some embodiments. In graph 800, the vertical axis represents temperature of a motor (e.g., a reticle stage motor) and the horizontal axis represents time. The time scale of events in graph 800 is given as an example for discussion, and not as a limitation. Plot 802 represents typical motor temperatures during a lithographic process when using, for example, an "always cool" thermal control system as described with reference to fig. 7. The data in graph 800 may be generated by using a temperature sensor as described above with reference to fig. 7. Time length 804 represents the length of time for a wafer exposure process, and time length 806 represents the length of time for a reticle exchange process. The wafer exposure and reticle exchange processes may be repeated multiple times in succession depending on the number of layers to be patterned onto the substrate. Region 808 indicates a behavior of interest (e.g., thermal cycling) related to the temperature of the motor.

As stated previously, the motor in operation has a nominal operating temperature. In the case of the motor represented by graph 800, the nominal temperature is indicated by dashed line 810 and is slightly above 70 ℃. The thermal fluctuations (e.g., small sawtooth patterns) shown in plot 802 are for illustration purposes and are not limiting. For example, thermal fluctuations may be presented at a flat portion of plot 802. During a length of time 804, graph 802 shows that the motor temperature is maintained approximately at the nominal operating temperature. The nominal operating temperature rise is due to the motor continuously providing acceleration and deceleration motion during wafer exposure with almost no idle periods. However, during time length 806, the motor enters an idle period such that the motor is continuously cooled by the "always cool" thermal control system. The length of time 806 is long enough for the motor to be close to the temperature of the cooling fluid in the thermal control system (e.g., room temperature or about 20 c to 25 c). The temperature change in the thermal cycle shown in zone 808 is approximately 50 ℃. When the reticle exchange process is complete, the motor begins to run, the motor temperature ramps up to the nominal operating temperature, and the process repeats. Thermal cycling can create stress at the interface where materials with different CTEs meet (e.g., the epoxy interface between the heat transfer element 708 and the electric machine 702 in fig. 7). The exact temperature values represented by plot 802 are given as an example and not a limitation, as performance may vary depending on, for example, the type of lithographic apparatus, motor, and process.

Although one thermal cycle may not immediately lead to motor failure (e.g., separation of epoxy), the number of thermal cycles may approach millions over the typical lifetime of a lithographic apparatus. In a rough estimate, approximately 735,000 thermal cycles will occur at 12 reticle exchanges per hour over 7 years of use of the lithographic apparatus. Each thermal cycle can cause cumulative damage at the CTE-mismatched interface, thereby accelerating premature failure of the motor. Embodiments of the present disclosure provide structures and methods for reducing or eliminating thermal cycling of motors in a lithographic apparatus.

FIG. 9 depicts a schematic view of a sub-portion 900 of a lithographic apparatus according to some embodiments. In some embodiments, subsection 900 includes an electric motor 902, a thermal control system 904, and a controller 906. The sub-section 900 also includes a heat transfer member 908 (e.g., a cold plate). In some embodiments, subsection 900 also includes a temperature sensor 910. The motor 902 includes coils 912 (e.g., as in a lorentz force motor). The number of coil elements shown is for illustration and not limitation. The thermal control system 904 includes a conduit system 914. The catheter system 914 includes a supply line 916 and a return line 918. In some embodiments, the conduit system 914 also includes a bypass line 920 and one or more valves 922. In some embodiments, subsection 900 also includes a communication channel 924. In some embodiments, sub-portion 900 includes heating element 926.

In some embodiments, a valve of the one or more valves 922 is provided to bisect the supply line 916. In some embodiments, other valves of the one or more valves 922 are disposed to bisect the return line 918. One or more valves 922 may form a conduit arrangement using a bypass line 920 to bypass the motor 902 — that is, one or more valves 922 are connected with the bypass line 920. Although the controller 906 is shown as being external to the thermal control system 904, in some embodiments, the controller 906 may be disposed within the thermal control system 904. The controller 906 may be in communication (e.g., electronically) with the temperature sensor 910 and the thermal control system 904. Specifically, the controller 906 may be in communication with one or more valves 922 of the catheter system 914. The temperature sensor is disposed on or near the motor 902. The heat transfer member 908 is adhered to the electric machine 902 using an adhesive for thermal coupling (e.g., an epoxy resin having high thermal conductivity). Some advantages of using adhesives are lower coverage areas such as cost effectiveness and volume reduction. The heat transfer element 908 may be part of the thermal control system 904 in a permanent arrangement (e.g., welded to the conduit system 914). In some embodiments, the heating element 926 is disposed on or near the motor 902.

In some embodiments, motor 902 is configured to move a stage (e.g., reticle stage 200 in fig. 2) in the lithographic apparatus. Thermal coupling via heat transfer member 908 allows thermal communication between electric machine 902 and thermal control system 904. The conduit system 914 is configured to circulate a heat transfer fluid (e.g., water) to the heat transfer element 908 and the motor 902, and to circulate the heat transfer fluid (e.g., water) away from the heat transfer element 908 and the motor 902. The thermal control system 904 is configured to regulate (e.g., adjust or maintain) the temperature of the motor 902. The controller 906 is configured to send temperature adjustment instructions to components in the lithographic apparatus, for example to the thermal control system 904 or other components of the lithographic apparatus external to the sub-section 900.

Shutting down and then restarting the thermal control system to temporarily resolve the (work around) "always cool" scenario is a crude solution and may not be feasible. Some reasons for this include, for example, inadequate timing accuracy to avoid thermal cycling, greater stress burden on other mechanical and electrical components, and power inefficiency, among others. Accordingly, in some embodiments, the controller 906 is configured to actuate one or more valves 922 to reduce or stop circulation of the heat transfer fluid during times when thermal cycling (e.g., reticle exchange of zone 808 of fig. 8) is expected to occur. This may be accomplished, for example, by the controller 906 sending temperature adjustment instructions to the thermal control system 904 to actuate one or more valves 922, which are used to divert the heat transfer fluid to the bypass line 920. In such a scenario, the temperature adjustment instructions include instructions to actuate one or more valves 922. In some embodiments, one or more valves 922 may be used to stop the flow of heat transfer fluid through the thermal control system 904. The use of valves is particularly useful because many lithographic apparatuses in the field can be easily modified outside them without having to open the lithographic apparatus and compromise its clean environment. In some embodiments, one or more valves 922 and bypass lines 920 may be implemented on the exterior of the lithographic apparatus into which the supply and return lines are fed.

Embodiments of the present disclosure also provide methods of adjusting the temperature of a motor in a lithographic apparatus with minimal, or even no, structural changes. In some embodiments, the controller 906 is configured to supply an AC current or voltage (e.g., high frequency) to the motor (e.g., to the coil 912). The high frequency of the AC current or voltage causes the direction of the force in the motor to continuously reverse at a faster rate than it can generate significant momentum in any particular direction (e.g., motor idling). The controller 906 may supply AC current or voltage directly. In some embodiments, the controller 906 may supply the AC current or voltage indirectly by using a device external to the controller 906 or the subsection 900. The controller 906 is configured to send the temperature adjustment instructions to other components (not shown) external to the subsection 900 using the communication channel 924. The component that receives the temperature adjustment command may be, for example, a power supply for driving a coil 912 of the motor 902. The power supply is configured to supply an AC current or voltage to the coil. In such a scenario, the temperature adjustment instructions include instructions that cause the power supply to provide an AC current or voltage to the motor causing the motor to generate joule heating. The frequency of the AC current or voltage is such that the motor is idling, but joule heating is still generated from the AC current or voltage flowing through coil 912. The phenomenon of joule heating can be described as heat dissipated when a current flows through a medium of finite impedance.

In some embodiments, each of the coils 912 is electrically independent of the other coils. In some embodiments, the controller 906 is configured to supply a current to a first one of the coils 912 and a second current to a second one of the coils 912. The controller 906 may directly supply the first current and the second current. In some embodiments, the controller 906 may supply the first current and the second current indirectly by using a device external to the controller 906 or the subsection 900. The means for receiving the temperature adjustment command may be, for example, a power supply for driving a coil 912 of the motor 902. The power supply is configured to supply the first current and the second current. In such a scenario, the temperature adjustment instructions include instructions that cause the power supply to provide the first current to the first coil and the second current to the second coil to cause the motor to generate joule heating during the idle period. The first and second currents are selected such that the motor force generated by the first coil is opposite to the motor force generated by the second coil-the so-called null solution. Thus, the motor idles, i.e., idles, as the current flowing through coil 912 produces joule heating.

Embodiments involving AC current (or voltage) or null solutions are advantageous because they can be implemented with minimal or no structural change. However, if structural changes within the lithographic apparatus are allowed, heating elements may be introduced. In embodiments that include a heating element 926, the controller 906 is configured to adjust the heat output of the heating element 926 so as to maintain the temperature of the motor while the motor is idling. In such a scenario, the temperature adjustment instructions include instructions that cause the heating element to heat the electric machine during an idle period.

Any of the embodiments involving valves and bypasses, AC current (or voltage), nulls, or heating elements may be implemented in any combination (e.g., valves and bypasses with nulls, or AC current itself, etc.). Thus, in some embodiments, one or more of valve 922, bypass line 920, and/or heating element 926 may be omitted. Furthermore, any component described herein that may participate in supplying or removing heat from the motor (e.g., the thermal control system 904, one or more valves 922, or a power supply that provides current for a zero solution or AC current solution, among others) may be referred to herein as a "thermal regulation component" of the lithographic apparatus.

In some embodiments, temperature sensor 910 is configured to generate motor temperature information. The controller 906 is configured to receive motor temperature information and determine a temperature adjustment command based on the motor temperature information.

Although a single motor may be depicted or described with reference to some embodiments of fig. 7-10, those skilled in the art will appreciate that the structures and methods described herein may be applied to systems (e.g., lithographic apparatus) having multiple motors. For example, two motors may implement the thermal cycle avoidance solution described herein with or without simple modifications to the related embodiments (e.g., two pairs of supply/return lines in series may have two bypass lines or a single bypass line before the supply/return lines split).

In some embodiments, without completely preventing thermal cycling, the temperature difference between the highest and lowest temperatures of the motor is reduced, at least during the idle period (e.g., reticle exchange of region 808 of fig. 8), as compared to an "always cool" setting. In some embodiments, the difference between the maximum temperature and the minimum temperature of the motor during the idle period is reduced by more than about 20% compared to the "always cool" setting. In some embodiments, the difference between the maximum temperature and the minimum temperature of the motor during the idle period is reduced by more than about 40% compared to the "always cool" setting. In some embodiments, the difference between the maximum temperature and the minimum temperature of the motor during the idle period is reduced by more than about 60% compared to the "always cool" setting. In some embodiments, the difference between the maximum temperature and the minimum temperature of the motor during the idle period is reduced by more than about 80% compared to the "always cool" setting. In other words, a significant temperature drop of the motor is reduced by the relative amount described above.

FIG. 10 illustrates method steps for adjusting temperature during idling of a motor of a stage in a lithographic apparatus according to some embodiments. In step 1002, an idle rotation of a motor of a stage in the lithographic apparatus is initiated. In step 1004, motor temperature information is sent to the controller during idle. In step 1006, a temperature adjustment command is determined based on the motor temperature information. In step 1008, temperature adjustment instructions are sent to a thermal adjustment component of the lithographic apparatus. In step 1010, a temperature of the motor during idling is adjusted using a thermal adjustment component such that a difference between a highest temperature and a lowest temperature of the motor during idling is reduced. In some embodiments, the motor temperature information is generated by a temperature sensor disposed on or near the motor. Those skilled in the art will appreciate that the steps may be omitted or rearranged. For example, in embodiments lacking motor temperature information (e.g., lacking a temperature sensor), steps 1002 and 1004 may be omitted.

Other aspects of the invention are set forth in the following numbered aspects:

1. a lithographic apparatus, the lithographic apparatus comprising:

an illumination system configured to illuminate a pattern of a patterning device;

a projection system configured to project an image of the pattern onto a substrate;

a stage configured to support the patterning device or the substrate;

a motor configured to move the platform;

a thermal control system configured to regulate a temperature of the electric machine; and

a controller configured to control a temperature of the motor during idling of the motor such that a difference between a highest temperature and a lowest temperature of the motor during idling is reduced.

2. The lithographic apparatus of aspect 1, further comprising a temperature sensor disposed on or near the motor, the temperature sensor configured to generate motor temperature information, wherein the controller is further configured to:

receiving the motor temperature information;

determining a temperature adjustment command based on the motor temperature information; and

sending the temperature adjustment command to the thermal control system to maintain a temperature of the electric machine during idle.

3. The lithographic apparatus of aspect 1, wherein the thermal control system comprises a conduit system thermally coupled to a motor, and the conduit system is configured to circulate a heat transfer fluid to and from the motor.

4. The lithographic apparatus of aspect 3, wherein the heat transfer fluid comprises water.

5. The lithographic apparatus of aspect 3, wherein:

the conduit system comprises one or more valves; and is

The controller is further configured to actuate the one or more valves to reduce or stop circulation of the heat transfer fluid to maintain the temperature of the motor during idle.

6. The lithographic apparatus of aspect 1, wherein:

the controller is further configured to supply an AC current to the motor to maintain a temperature of the motor during idle; and is

The AC current has a frequency that causes the motor to freewheel.

7. The lithographic apparatus of aspect 1, wherein:

the motor includes a first coil and a second coil electrically independent from the first coil;

the controller is further configured to supply a first current to the first coil and a second current to the second coil to maintain a temperature of the motor during idling; and is

The first and second currents generate opposing forces causing the motor to freewheel.

8. The lithographic apparatus of aspect 1, further comprising a heating element disposed on or near the motor, wherein the controller is further configured to allow the heating element to heat the motor, thereby maintaining a temperature of the motor during idle.

9. A method of regulating temperature during idling of a motor of a stage in a lithographic apparatus, the method comprising:

initiating an idle rotation of the motor of the stage in the lithographic apparatus;

sending a temperature adjustment instruction to a thermal adjustment component of the lithographic apparatus; and

adjusting a temperature of the motor during idling using the thermal adjustment component such that a difference between a highest temperature and a lowest temperature of the motor during idling is reduced.

10. The method of aspect 9, further comprising:

generating motor temperature information using a temperature sensor disposed on or near the motor;

sending the motor temperature information to a controller during idling; and

determining the temperature adjustment command based on the motor temperature information.

11. The method of aspect 10, wherein:

the lithographic apparatus comprises a thermal control system comprising a conduit system configured to circulate a heat transfer fluid to and from the motor, the conduit system comprising one or more valves, and the adjusting comprises actuating the one or more valves to reduce or stop circulation of the heat transfer fluid to maintain the temperature of the motor during idle; and/or

The lithographic apparatus comprises a heating element disposed on or near the motor, and the adjusting comprises heating the motor using the heating element to maintain a temperature of the motor during idling.

12. The method of aspect 9, wherein:

the adjusting comprises supplying an AC current to the motor to maintain a temperature of the motor during idling, the AC current having a frequency such that the motor idles; and/or

The motor includes a first coil and a second coil, and the adjusting includes supplying a first current to the first coil and a second current to the second coil to maintain a temperature of the motor during freewheeling, the first current and the second current generating opposing forces such that the motor freewheels.

13. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by a controller, cause the controller to perform operations comprising:

starting idling of a motor of a stage in the lithographic apparatus;

sending a temperature adjustment instruction to a thermal adjustment component of the lithographic apparatus; and

adjusting a temperature of the motor during idling using the thermal adjustment component such that a difference between a highest temperature and a lowest temperature of the motor during idling is reduced.

14. The non-transitory computer-readable medium of aspect 13, wherein the operations further comprise:

receiving motor temperature information generated by a temperature sensor disposed on or near the motor; and

determining the temperature adjustment command based on the motor temperature information.

15. The non-transitory computer-readable medium of aspect 13, wherein:

the lithographic apparatus comprises a thermal control system comprising a conduit system configured to circulate a heat transfer fluid to and from the motor, the conduit system comprising one or more valves, and the adjusting comprises actuating the one or more valves to reduce or stop circulation of the heat transfer fluid to maintain the temperature of the motor during idle; and/or

The lithographic apparatus comprises a heating element disposed on or near the motor, and the adjusting comprises heating the motor using the heating element to maintain a temperature of the motor during idling.

16. The non-transitory computer-readable medium of aspect 13, wherein:

the adjusting comprises supplying an AC current to the motor to maintain a temperature of the motor during idling, the AC current having a frequency such that the motor idles; and/or

The motor includes a first coil and a second coil, and the adjusting includes supplying a first current to the first coil and a second current to the second coil to maintain a temperature of the motor during freewheeling, the first current and the second current generating opposing forces such that the motor freewheels.

17. A system for maintaining a temperature of an actuator during an idle period of the actuator, the system comprising:

a table configured to support an article;

an actuator configured to move the stage;

a thermal control system configured to regulate a temperature of the actuator; and

a controller configured to control a temperature of the actuator during the idle such that a difference between a highest temperature and a lowest temperature of the actuator during the idle is reduced.

18. The system of aspect 17, further comprising a temperature sensor disposed on or near the actuator, the temperature sensor configured to generate actuator temperature information, wherein the controller is further configured to:

receiving the actuator temperature information;

determining a temperature adjustment command based on the actuator temperature information; and

sending the temperature adjustment command to the thermal control system to maintain the temperature of the actuator during idle.

19. The system of aspect 17, wherein:

the thermal control system comprises a conduit system thermally coupled to the actuator and configured to circulate a heat transfer fluid to and from the actuator, the conduit system comprising one or more valves, and the controller is further configured to actuate the one or more valves to reduce or stop circulation of the heat transfer fluid to maintain the temperature of the actuator during idle; and/or

The system includes a heating element disposed on or near the actuator, and the controller is further configured to allow the heating element to heat the actuator to maintain a temperature of the actuator during idle.

20. The system of aspect 17, wherein:

the controller is further configured to supply an AC current to the actuator to maintain a temperature of the actuator during idling, the AC current having a frequency that causes the actuator to idle; and/or

The actuator includes a first coil and a second coil electrically independent of the first coil, and the controller is further configured to supply a first current to the first coil and a second current to the second coil to maintain a temperature of the actuator during freewheeling, the first current and the second current generating opposing forces such that the actuator freewheels.

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. Possible other applications include the manufacture of integrated optical systems, guidance and detection for magnetic domain memories, flat panel displays, Liquid Crystal Displays (LCDs), thin film magnetic heads, etc.

Although specific reference may be made in this text to embodiments of the disclosure in the context of lithographic apparatus, embodiments of the disclosure may be used in other apparatus. Embodiments of the present disclosure may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or a mask (or other patterning device). These devices may be generally referred to as lithographic tools. These lithography tools may use vacuum conditions or ambient (non-vacuum) conditions.

Although specific reference may have been made in detail to the use of embodiments of the disclosure in the context of optical lithography, it will be understood that the disclosure is not limited to optical lithography, and may be used in other applications, such as imprint lithography, where the context allows. In another example, embodiments described herein may be applied to actuators having a movable table and platform for supporting an object in other machines and systems.

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 specification is to be interpreted by the skilled artisan in light of the teachings herein.

The above examples are illustrative, but not limiting, of embodiments of the disclosure. Other suitable modifications and adaptations of the various conditions and parameters normally encountered in the art and which would be apparent to one skilled in the relevant art are within the spirit and scope of the present disclosure.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not restrictive. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

It should be understood that what is intended to be used to interpret the claims is the detailed description section, not the summary and abstract sections. The summary and abstract sections may set forth one or more, but not all exemplary embodiments of the present disclosure as contemplated by the inventors, and are therefore not intended to limit the disclosure and the appended claims in any way.

The invention has been described above with the aid of functional building blocks illustrating the implementation of specific functions and relationships thereof. Boundaries of these functional components have been arbitrarily defined herein for convenience of description. Other boundaries may be defined so long as the specified functions and relationships thereof are appropriately performed.

The foregoing description of the specific embodiments will so fully reveal the general nature of the invention 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 invention. Therefore, based on the teachings and guidance presented herein, these changes and modifications are intended to fall within the meaning and scope of equivalents of the disclosed embodiments.

The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.