Lift pin assembly for loading / unloading substrate, stage, and lithographic apparatus

Abstract

A lift pin assembly for loading / unloading a substrate, the assembly comprising: a plurality of support pins, the number of the plurality of support pins being more than 3; the apparatus includes a plurality of support pins, an actuator assembly configured to cause displacement of the plurality of support pins, and a control unit configured to control the displacement of the plurality of pins to pre-shape the substrate when the substrate is loaded / unloaded.

Description

Cross-references to related applications

[0001] This application claims priority to EP application 23188683.9, filed on July 31, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to a lifting pin assembly, for example, a lifting pin assembly that can be applied to the platform equipment of a lithography machine. Background Technology

[0003] A lithography apparatus is a machine configured to apply a desired pattern onto a substrate. Lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithography apparatus can project, for example, a pattern (often referred to as a “design layout” or “design”) from a patterning apparatus (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate (e.g., a wafer).

[0004] As semiconductor manufacturing processes continue to advance, the size of circuit components has shrunk dramatically, while the number of functional elements (such as transistors) in each device has steadily increased over the decades, following a trend commonly known as "Moore's Law." To keep pace with Moore's Law, the semiconductor industry is pursuing technologies capable of creating increasingly smaller features. To project patterns onto a substrate, photolithography equipment uses electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features that can be patterned on the substrate. Typical wavelengths currently used are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Compared to photolithography equipment using radiation with a wavelength of, for example, 193 nm, photolithography equipment using extreme ultraviolet (EUV) radiation in the range of 4 nm to 20 nm (e.g., 6.7 nm or 13.5 nm) can be used to form even smaller features on the substrate.

[0005] Semiconductor manufacturing processes using photolithography equipment may require multiple transfers of the substrate from one location to another, during which the substrate undergoes various processes or process steps. During these processes, the substrate can be clamped onto a stage. To load / unload the substrate from or onto such a stage, lifting pins are typically used to raise or lower the substrate onto the stage.

[0006] Currently, there is a frequent need to process substrates with a certain degree of warpage. It has been observed that current tools used during substrate loading / unloading may be insufficient to ensure proper loading / unloading of the substrate. In particular, loading or unloading a warped substrate can lead to wear on the substrate or stage. Summary of the Invention

[0007] The purpose of this invention is to improve the loading / unloading of substrates.

[0008] According to an aspect of the present invention, a lifting pin assembly for loading / unloading a substrate is provided, comprising: Multiple support pins, wherein the number of the multiple support pins is more than 3; Actuator assembly, the actuator assembly being configured to cause displacement of the plurality of support pins, and A control unit configured to control the displacement of the plurality of pins to pre-shape the substrate during loading / unloading.

[0009] According to an aspect of the invention, a stage is provided, the stage including a lifting pin assembly according to the invention.

[0010] According to an aspect of the present invention, a photolithography apparatus is provided, the photolithography apparatus including a stage according to the present invention. Attached Figure Description

[0011] Embodiments of the invention will now be described by way of example only, with reference to the accompanying schematic diagrams, in which: Figure 1 A schematic diagram of a photolithography apparatus is depicted: Figure 2 Depicting Figure 1 A detailed view of a part of the lithography equipment; Figure 3 The position control system is schematically depicted; Figure 4 A first embodiment of the lifting pin assembly according to the present invention is depicted. Figure 5 A second embodiment of the lifting pin assembly according to the present invention is described. Figure 6 A third embodiment of the lifting pin assembly according to the present invention is described. Figure 7 The process of loading a substrate using the lifting pin assembly according to the invention is described. Figure 8-10 A support pin that can be applied to a lifting pin assembly according to the present invention is described. Detailed Implementation

[0012] In this document, the terms “radiation” and “beam” are used to cover all types of electromagnetic radiation, including ultraviolet radiation (e.g., having wavelengths of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., having wavelengths in the range of about 5 nm to 100 nm).

[0013] As used herein, the terms “mask,” “mask,” or “patterning apparatus” can be broadly interpreted to refer to a general patterning apparatus that can be used to impart a patterned cross-section to an incident radiation beam corresponding to a pattern to be produced in a target portion of a substrate. The term “optical valve” may also be used in this context. Examples of such patterning apparatuses, besides classic masks (transmissive or reflective masks, binary masks, phase-shifting masks, hybrid masks, etc.), include programmable mirror arrays and programmable LCD arrays.

[0014] Figure 1 A lithography apparatus LA is schematically depicted. The lithography apparatus LA includes: an irradiation system (also called an irradiator) IL configured to modulate a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation); a mask support (e.g., a mask stage) MT configured to support a patterning apparatus (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning apparatus MA according to specific parameters; a substrate support (e.g., a wafer stage) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioner PW configured to accurately position the substrate support according to specific parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted by the radiation beam B by the patterning apparatus MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.

[0015] In operation, the irradiation system IL receives a radiation beam from the radiation source SO, for example, via a beam transmission system BD. The irradiation system IL may include various types of optical components for guiding, shaping, and / or controlling the radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof. The irradiator IL can be used to adjust the radiation beam B to have a desired spatial and angular intensity distribution in its cross-section at the plane of the pattern forming apparatus MA.

[0016] As used herein, the term "projection system" PS should be broadly interpreted to encompass various types of projection systems, including refractive optical systems, reflective optical systems, refractive-reflective optical systems, distorting optical systems, magnetic optical systems, electromagnetic and / or electrostatic optical systems, or any combination thereof, applicable to the exposure radiation and / or other factors (such as the use of immersion liquids or vacuum). Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" PS.

[0017] A lithography apparatus LA can be of the type in which at least a portion of the substrate can be covered by a liquid (e.g., water) having a relatively high refractive index to fill the space between the projection system PS and the substrate W; this is also known as immersion lithography. More information about immersion techniques is given in US6952253 (US6952253 is incorporated herein by reference).

[0018] The lithography apparatus LA can also be of the type having two (also known as "dual-stage") or more substrate supports WT. In such a "multi-stage" machine, the substrate supports WT can be used in parallel, and / or while performing subsequent exposure preparation steps on a substrate W located on one of the substrate supports WT, another substrate W on another substrate support WT can be used to expose a pattern on the other substrate W.

[0019] To load / unload the substrate W from the substrate support WT, the substrate support WT may include a lifting pin assembly according to the invention. Further details of such a lifting pin assembly are given below.

[0020] In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure the properties of the projection system PS or the properties of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning devices may be arranged to clean part of the lithography apparatus, such as part of the projection system PS or part of a system providing immersion liquid. The measurement stage may move below the projection system PS as the substrate support WT moves away from the projection system PS.

[0021] In operation, a radiation beam B is incident on a pattern forming apparatus (e.g., a mask) MA held on a mask support MT and patterned by a pattern (design layout) present on the pattern forming apparatus MA. After traversing the pattern forming apparatus MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of a second positioner PW and a position measurement system IF, the substrate support WT can be accurately moved, for example, to position different target portions C at focused and aligned positions along the path of the radiation beam B. Similarly, a first positioner PM and possibly another position sensor (the other position sensor is not in...) Figure 1(As explicitly shown in the diagram) can be used to accurately position the pattern forming apparatus MA relative to the path of the radiation beam B. The pattern forming apparatus MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks P1, P2 occupy dedicated target portions, they can be located in the space between the target portions. When the substrate alignment marks P1, P2 are located between the target portions C, they are referred to as scribing alignment marks.

[0022] For the purpose of illustrating this invention, a Cartesian coordinate system is used. A Cartesian coordinate system has three axes: the x-axis, the y-axis, and the z-axis. Each of the three axes is orthogonal to the other two axes. A rotation about the x-axis is called an Rx rotation. A rotation about the y-axis is called an Ry rotation. A rotation about the z-axis is called an Rz rotation. The x-axis and y-axis define the horizontal plane, while the z-axis is in the vertical direction. The Cartesian coordinate system is not limiting of this invention but is merely illustrative. Alternatively, other coordinate systems, such as cylindrical coordinates, can be used to illustrate this invention. The orientation of the Cartesian coordinate system can be different; for example, the z-axis can have a component along the horizontal plane.

[0023] Figure 2 It shows Figure 1 A more detailed view of a portion of a lithography apparatus LA. The lithography apparatus LA may include a base frame BF, a counterweight BM, a measurement frame MF, and a vibration isolation system IS. The measurement frame MF supports a projection system PS. Additionally, the measurement frame MF may support a portion of a position measurement system PMS. The measurement frame MF is supported by the base frame BF via the vibration isolation system IS. The vibration isolation system IS is configured to prevent or reduce vibrations propagating from the base frame BF to the measurement frame MF.

[0024] The second positioner PW is arranged to accelerate the substrate support WT by providing a driving force between the substrate support WT and the counterweight BM. The driving force accelerates the substrate support WT in the desired direction. Due to the conservation of momentum, the driving force is also applied to the counterweight BM in an equal order of magnitude, but in the opposite direction to the desired direction. Typically, the mass of the counterweight BM is significantly greater than the mass of the moving portions of the second positioner PW and the substrate support WT.

[0025] In one embodiment, the second positioner PW is supported by a counterweight BM. For example, the second positioner PW includes a planar motor to suspend the substrate support WT above the counterweight BM. In another embodiment, the second positioner PW is supported by a base frame BF. For example, the second positioner PW includes a linear motor and a bearing (such as a gas bearing) to suspend the substrate support WT above the base frame BF.

[0026] A position measurement system (PMS) can include any type of sensor suitable for determining the position of a substrate stage WT. A position measurement system (PMS) can include any type of sensor suitable for determining the position of a mask support MT. The sensor can be an optical sensor, such as an interferometer or encoder. A position measurement system (PMS) can include a combined system of interferometers and encoders. The sensor can be another type of sensor, such as a magnetic sensor, a capacitive sensor, or an inductive sensor. A position measurement system (PMS) can determine the position relative to a reference object (e.g., a measurement frame MF or a projection system PS). A position measurement system (PMS) can determine the position of the substrate stage WT and / or the mask support MT by measuring the position or by measuring the time derivative of the position (e.g., velocity or acceleration).

[0027] A position measurement system (PMS) may include an encoder system. For example, an encoder system is known from U.S. Patent Application US2007 / 0058173A1, filed September 7, 2006, which is incorporated herein by reference. The encoder system includes an encoder head, a grating, and a sensor. The encoder system can receive a primary radiation beam and a secondary radiation beam. Both the primary and secondary radiation beams originate from the same radiation beam, i.e., the original radiation beam. At least one of the primary and secondary radiation beams is generated by diffracting the original radiation beam with a grating. If both the primary and secondary radiation beams are generated by diffracting the original radiation beam with a grating, the primary radiation beam needs to have a different diffraction order than the secondary radiation beam. For example, different diffraction orders are +1, -1, +2, and -2. The encoder system optically combines the primary and secondary radiation beams into a combined radiation beam. A sensor in the encoder head determines the phase or phase difference of the combined radiation beam. The sensor generates a signal based on the phase or phase difference. This signal indicates the position of the encoder head relative to the grating. One of the encoder head and the grating can be arranged on the substrate structure WT. The other of the encoder head and the grating can be arranged on the measurement frame MF or the base frame BF. For example, multiple encoder heads are arranged on the measurement frame MF, while the grating is arranged on the top surface of the substrate support WT. In another example, the grating is arranged on the bottom surface of the substrate support WT, and the encoder head is arranged below the substrate support WT.

[0028] A position measurement system (PMS) may include an interferometer system. For example, an interferometer system is known from U.S. Patent 6,020,964, filed July 13, 1998, which is incorporated herein by reference. The interferometer system may include a beam splitter, a mirror, a reference mirror, and a sensor. A radiation beam is split into a reference beam and a measurement beam by the beam splitter. The measurement beam propagates to the mirror and is reflected back to the beam splitter. The reference beam propagates to the reference mirror and is reflected back to the beam splitter. At the beam splitter, the measurement beam and the reference beam are combined into a combined radiation beam. The combined radiation beam is incident on the sensor. The sensor determines the phase or frequency of the combined radiation beam. The sensor generates a signal based on the phase or frequency. This signal represents the displacement of the mirror. In one embodiment, the mirror is connected to a substrate support WT. The reference mirror may be connected to a measurement frame MF. In another embodiment, the measurement beam and the reference beam are combined into a combined radiation beam by additional optical components instead of a beam splitter.

[0029] The first positioner PM may include a long-stroke module and a short-stroke module. The short-stroke module is arranged to move the mask support MT with high accuracy relative to the long-stroke module within a small range of motion. The long-stroke module is arranged to move the short-stroke module with relatively low accuracy relative to the projection system PS within a large range of motion. Through the combination of the long-stroke and short-stroke modules, the first positioner PM can move the mask support MT with high accuracy relative to the projection system PS within a large range of motion. Similarly, the second positioner PW may include a long-stroke module and a short-stroke module. The short-stroke module is arranged to move the substrate support WT with high accuracy relative to the long-stroke module within a small range of motion. The long-stroke module is arranged to move the short-stroke module with relatively low accuracy relative to the projection system PS within a large range of motion. Through the combination of the long-stroke and short-stroke modules, the second positioner PW can move the substrate support WT with high accuracy relative to the projection system PS within a large range of motion.

[0030] The first positioner PM and the second positioner PW are each provided with actuators for moving the mask support MT and the substrate support WT, respectively. The actuator can be a linear actuator to provide a driving force along one axis (e.g., the y-axis). Multiple linear actuators can be applied to provide driving forces along multiple axes. The actuator can be a planar actuator to provide driving forces along multiple axes. For example, a planar actuator can be arranged to move the substrate support WT in six degrees of freedom. The actuator can be an electromagnetic actuator comprising at least one coil and at least one magnet. The actuator is arranged to move at least one coil relative to at least one magnet by applying current to at least one coil. The actuator can be a moving magnet type actuator having at least one magnet coupled to the substrate support WT and the mask support MT, respectively. The actuator can be a moving coil type actuator having at least one coil coupled to the substrate support WT and the mask support MT, respectively. The actuator can be a voice coil actuator, a magnetoresistive actuator, a Lorentz actuator, or a piezoelectric actuator, or any other suitable actuator.

[0031] Photolithography equipment (LA) includes, for example Figure 3 The diagram schematically depicts a position control system (PCS). The PCS includes a setpoint generator (SP), a feedforward controller (FF), and a feedback controller (FB). The PCS provides drive signals to an actuator (ACT). The actuator (ACT) can be an actuator of a first positioner (PM) or a second positioner (PW). The actuator (ACT) drives a mechanical plant (plant) P, which may include a substrate support (WT) or a mask support (MT). The output of the mechanical plant P is a position quantity (such as position, velocity, or acceleration). The position quantity is measured by a position measurement system (PMS). The PMS generates a signal representing the position quantity of the mechanical plant P. The setpoint generator (SP) generates a signal representing the desired position quantity of the mechanical plant P. For example, the reference signal represents the desired trajectory of the substrate support (WT). The difference between the reference signal and the position signal forms the input to the feedback controller (FB). Based on this input, the feedback controller (FB) provides at least a portion of the drive signal to the actuator (ACT). The reference signal may form the input to the feedforward controller (FF). Based on this input, the feedforward controller (FF) provides at least a portion of the drive signal to the actuator (ACT). Feedforward FF can utilize information about the dynamic characteristics of a mechanical device P, such as mass, stiffness, resonant modes, and eigenfrequency.

[0032] Figure 4 A top view (a) and a side view (b) of a lifting pin assembly 400 according to the present invention are schematically shown. According to the present invention, a lifting pin assembly for loading / unloading a substrate is disclosed. According to the present invention, the lifting pin assembly includes a plurality of support pins 410, the number of support pins 410 being greater than three. In such a way... Figure 4 In the illustrated embodiment, the lifting pin assembly 400 includes four support pins 410. Figure 4 In (b), the substrate is schematically shown by dashed line 402. According to the invention, the plurality of support pins 410 shown are displaceable. In particular, they are displaceable in the Z direction shown, which in practice typically corresponds to the vertical direction. Thus, according to the invention, the plurality of support pins can move upward or downward, thereby displacing the top surface 410.1 of the support pins in the vertical direction. According to the invention, the lifting pin assembly includes an actuator assembly configured to cause displacement of the plurality of support pins. In the embodiment shown, the actuator assembly includes a plurality of actuators 420 for displacing the plurality of support pins 410 respectively. In the embodiment shown, each of the plurality of support pins 410 is therefore fitted with an actuator 420. It can be noted that this is not necessarily the case. In embodiments, as will be explained below, two or more support pins may be displaced by a single common actuator.

[0033] In the embodiment shown, actuator assembly 420 is mounted to support frame 440. In such an embodiment, support 404 may correspond, for example, to the substrate stage WT as described above, and is positioned by a positioning device (such as a second positioner PW). In this case, support frame 440 and actuator assembly 420 may be mounted to a long-stroke module of the second positioner PW. In an alternative embodiment, support frame 440 may be mounted, for example, to the bottom surface of support 404 to support substrate 402. Alternatively, actuator assembly 420 may be integrated or directly mounted to support 404.

[0034] According to the present invention, the lifting pin assembly 400 further includes a control unit 430 for controlling the displacement of the plurality of support pins 410.

[0035] By controlling the displacement of the support pins 410, the control unit 430 can control the height or lift of the top surface 410.1 of the support pins 410, for example, relative to the support surface 404.1 of the support member 404 for the substrate 402. Note that the dashed line 404 schematically shows a support on which the substrate 402 can be supported or held. Such a support can be, for example, the aforementioned substrate stage WT. In the embodiment shown, the support member 404 includes a hole 404.2 through which the support pins 410 can protrude. In an embodiment, the support pins 410 can be displaced, for example, under the control of the control unit 430, such that the top surfaces 410.1 of the plurality of support pins 410 are arranged below the support surface 404.1. By doing so, the substrate 402 can be lowered until it rests on the support surface 404.1. This process, in which the substrate 402 is initially supported by the plurality of support pins 410 and subsequently positioned on the support surface of the support member 404, can be referred to as loading the substrate 402. The reverse process, in which substrate 402 is initially supported on the support surface 404.1 of support member 404 and then supported by multiple support pins 410 as support pins 410 are raised, can be referred to as unloading substrate 402. During unloading, a vertical gap typically appears between the support surface 404.1 and the bottom surface of substrate 402. A clamp can utilize this gap, for example, to hold substrate 402, for example, to transport the substrate to different locations.

[0036] According to the present invention, the control unit 430 of the lifting pin assembly is configured to control the displacement of a plurality of pins to pre-shape the substrate during loading / unloading. According to the present invention, the displacement of the plurality of support pins causes the shape of the substrate to be changed or modified during loading / unloading. Specifically, in embodiments of the invention, the curvature of the substrate can be reduced during loading or unloading. In embodiments, the pre-shaping of the substrate occurs before the substrate contacts the support member 404.

[0037] Currently, it has been observed that substrates to be processed (e.g., patterned substrates provided in photolithography equipment) are no longer flat, but are curved to some extent. This curvature of the substrate is also known as warping. The processing (especially of warped or curved substrates) can pose challenges to known equipment. It has also been observed that substrate loading and unloading can be adversely affected by substrate warping. To expose a substrate, for example, to a patterned radiation beam, it is typically clamped to a support, for example, by vacuum or electrostatic force. When a curved or warped substrate needs to be clamped, it can be difficult to achieve proper clamping. The substrate may deform during the process, or the required clamping force may be difficult to achieve. Furthermore, during the clamping process, portions of the substrate may shift relative to the support surface, for example, in the horizontal direction. This can damage the substrate and / or potentially generate debris. Additionally, this can lead to inaccurate local positioning of the substrate.

[0038] Using the lifting pin assembly according to the invention at least alleviates the aforementioned challenges and problems. With the lifting pin assembly according to the invention, pre-shaping of the substrate is applied during loading / unloading. Due to this pre-shaping, the substrate 402 can be more easily clamped onto the support 404, while reducing the risk of damage to the substrate 402 or the support 404. Generally, the invention enables the substrate 402 to be pre-shaped into a more desired shape during loading / unloading. In embodiments, this more desired shape can be a generally flat shape. However, this is not necessary. Alternative pre-shaping processes can also be considered, where the substrate is pre-shaped, for example, toward a slightly curved shape.

[0039] Figure 5 Another embodiment of the lifting pin assembly 500 according to the invention is illustrated schematically. Except for the positions of the plurality of support pins 510 within the assembly 500, the lifting pin assembly 500 substantially corresponds to... Figure 4 The lifting pin assembly 400 shown is illustrated.

[0040] According to the present invention, the lifting pin assembly 500 includes a plurality of support pins 510, and the number of support pins 510 is more than three. In such cases... Figure 5 In the illustrated embodiment, the lifting pin assembly 500 includes four support pins 510. In the arrangement shown, the support pins 510 include a central support pin 510a and three outer support pins 510b arranged in a triangular configuration. Figure 5 In (b), the substrate is schematically shown by dashed line 502. In the arrangement shown, a plurality of support pins 510 are displaceable by a plurality of corresponding actuators 520 of the actuator assembly.

[0041] According to the present invention, the lifting pin assembly 500 further includes a control unit 530 for controlling the displacement of the plurality of support pins 510.

[0042] By controlling the displacement of the support pins 510, the control unit 530 can control the height or lift of the top surface 510.1 of the support pins 510, for example, relative to the support surface 504.1 of the support member 504 for the substrate 502. Specifically, the control unit 530 of the lifting pin assembly is configured to control the displacement of the plurality of pins 510 to pre-shape the substrate 502 during loading / unloading. By doing so, warpage of the substrate being loaded or unloaded can be taken into account, and the shape of the substrate can be adjusted to achieve improved loading or unloading of the substrate.

[0043] Figure 6 Another embodiment of the lifting pin assembly 600 according to the present invention is illustrated schematically. According to the present invention, the lifting pin assembly 600 includes a plurality of support pins 610, the number of support pins 610 being more than three. In such a way... Figure 6 In the illustrated embodiment, the lifting pin assembly 600 includes six support pins 610. In the arrangement shown, the plurality of support pins 610 includes a first group of three support pins 610a arranged in a triangular configuration near the center of the assembly, and three outer support pins 610b also arranged in a triangular configuration. Figure 6 In (b), the substrate is schematically shown by dashed line 602. In the arrangement shown, a plurality of support pins 610 can be displaced by an actuator assembly 620 comprising a plurality of actuators. In the arrangement shown, each outer support pin 610b is equipped with a dedicated actuator 620b of the actuator assembly 620 for displacing or moving the pin. A first set of pins 610a arranged at the center of the lifting pin assembly 600 is configured to be displaced by a common actuator 620a of the actuator assembly 620. In this case, the first set of pins 610a can be arranged on a common frame, which can be displaced, for example, in the vertical or Z-direction by the actuator 620a.

[0044] According to the present invention, the lifting pin assembly 600 further includes a control unit 630 for controlling the displacement of the plurality of support pins 610.

[0045] By controlling the displacement of the support pins 610, the control unit 630 can control the height or lift of the top surface 610.1 of the support pins 610, for example, relative to the support surface 604.1 of the support member 604 for the substrate 602. Specifically, the control unit 630 of the lifting pin assembly is configured to control the displacement of the plurality of pins 610 to pre-shape the substrate 602 during substrate loading / unloading. By doing so, warpage of the substrate being loaded or unloaded can be taken into account, and the shape of the substrate can be adjusted to achieve improved loading or unloading of the substrate.

[0046] As Figure 6In an alternative to the illustrated embodiment, the first set of support pins 610a may also include a single support pin instead of a set of three support pins. Such a single support pin may, for example, be positioned at the center position 612 of the lifting pin assembly. It can also be noted that, as... Figure 4 The lifting pin assembly 400 shown may also be equipped with one or more additional support pins arranged at or near the center of the assembly.

[0047] In embodiments of the invention, a plurality of support pins applied in the lifting pin assembly according to the invention are configured to apply a holding force to the substrate. In this arrangement, the plurality of support pins (as a whole) are able to hold the substrate, thereby ensuring that the substrate (e.g., substrates 402, 502, 602 described above) remains in a substantially fixed position relative to the support pins or the top surface of the support pins. It can be noted that, in order to apply a holding force to the substrate, not all support pins need to be able to apply a holding force to the substrate. Thus, in embodiments, a subset of the plurality of support pins is configured to apply a holding force to the substrate.

[0048] To generate this retaining force, one or more of the support pins of the lifting pin assembly according to the invention can be configured to apply an attractive force to the bottom surface of the substrate being loaded / unloaded. This attractive force can be generated, for example, by vacuum or electrostatic means. This will be explained in more detail below.

[0049] Within the context of this invention, the holding force or attraction force can also be referred to as clamping force.

[0050] Figure 7 The process of pre-shaping a substrate during loading / unloading is illustrated schematically using the lifting pin assembly according to the invention.

[0051] Figure 7 (a) A substrate 702 is schematically shown, held above a substrate support 704 by a clamp 705. The substrate support 704 includes a lifting pin assembly 700 according to the invention, which includes a plurality of support pins 710. In the arrangement shown, the lifting pin assembly 700 includes a central pin 710a and a plurality (e.g., 3 or 4) of support pins 710b arranged radially toward the edge of the substrate 702.

[0052] In the arrangement shown in the figure, the substrate 702 has a curvature and is umbrella-shaped.

[0053] It is also assumed that the central support pin 710a is configured to apply a holding force or clamping force to the substrate 702.

[0054] From such Figure 7 Starting from the initial position shown in (a), Figure 7(b)-(d) illustrate the various stages of the loading process of a substrate using the lifting pin assembly 700 according to the invention. Figure 7 (b) shows the component 700 in a position where the support pins 710 have risen to the level of the bottom surface of the substrate 702. This rise of the support pins 710 can be achieved by the actuator component 720 of the lifting pin assembly 700.

[0055] Due to the umbrella shape of the substrate 702, the lifting or displacement of the central support pin 710a will be greater than the lifting or displacement of the external support pin 710b of the component 700.

[0056] When the substrate 702 is supported by the plurality of support pins 710 of the lifting pin assembly 700, the substrate can actually be transferred to the lifting pin assembly 700. This can be achieved, for example, by lowering and retracting the gripper 705, so that the substrate 702 is supported only by the support pins of the lifting pin assembly 700. Alternatively or additionally, the support pins 710 can be raised slightly further so that the gripper 705 can be retracted.

[0057] To ensure that the substrate 702 remains fixed to the support pins 710, in embodiments of the invention, a plurality of support pins 710 are configured to apply a holding force to the substrate 702, thereby ensuring that the substrate 702 does not separate from the support pins 710. However, it can generally be noted that the invention can be applied without applying a holding force to the substrate via the support pins 710. In this case, gravity acting on the substrate 402 is sufficient to hold the substrate. In particular, for the pre-shaping of thin or very thin substrates, it can be noted that such substrates can be pre-shaped simply by appropriate displacement of a plurality of support pins, as applied in the lifting pin assembly according to the invention.

[0058] According to the present invention, once the fixture 705 has been retracted, the substrate 702 can be pre-shaped. For example... Figure 7 As shown in (c). Figure 7 (c) illustrates a stage in the loading process where the lifting or displacement of the support pins 710 has been modified to adjust the shape of the substrate 702. Specifically, the lifting or displacement of the support pins 710 has been adjusted to reduce the curvature of the substrate 702. For the given example, this corresponds to applying a tensile or downward force 712a to the substrate 702 via the central support pin 710a, and / or a thrust 712b via the radially outer support pins 710b. Within the context of this invention, one or more forces required to pre-shape the substrate may be referred to as pre-shaping forces. The required pre-shaping forces typically depend on the actual shape of the substrate to be loaded / unloaded, the stiffness of the substrate, and the desired shape of the substrate.

[0059] As those skilled in the art will understand, the force applied to the substrate by the lifting pin assembly according to the present invention can be twofold: A first force component applied to the substrate during the loading / unloading process, as described above, can be applied to ensure that the substrate remains attached or held by the support pins. This first component may also be referred to as a clamping force, which clamps the substrate to the top surface of the plurality of support pins of the lifting pin assembly according to the invention. Note that not all of the plurality of support pins need to participate in generating this clamping or holding force. The second force component applied to the substrate during the loading / unloading process is the pre-shaping force, i.e. the force required to adjust / modify the shape of the substrate.

[0060] In embodiments, the control of two force components, namely the clamping force and the pre-shaping force, can be controlled by a control unit of the lifting pin assembly according to the invention. Alternatively, the forces can be controlled independently, for example, by different control units. As will be understood, the properties of the two force components and the manner in which they are applied are significantly different; to apply the clamping force, that is, the force component that holds the substrate attached to the support pins, an attractive force is generated between the top surface of at least one of the support pins and the bottom surface of the substrate. This attractive force can be generated, for example, by a vacuum force or an electrostatic force. This clamping force can be applied once the support pins approach or contact the bottom surface of the substrate to hold the substrate in position relative to the support pins. The pre-shaping force is a force designed to adjust the shape of the held substrate. Figure 7 As shown in the examples in (b) / (c), this may require shifting multiple support pins while maintaining the clamping force that holds the substrate on the support pins. For example, Figure 7 (b) shows an umbrella-shaped substrate 702, which requires applying a pulling force or a downward force 712a to the substrate 702 via a central support pin 710a (e.g., by lowering the pin), and / or applying a pushing force 712b via radially outer support pins 710b (e.g., by raising the pins). In an embodiment, the displacement of the support pins holding the substrate 702 is such that the top surfaces of the plurality of support pins are in substantially the same plane. The pre-shaping force required to achieve this depends on the warpage amplitude of the substrate, the stiffness of the substrate, and the desired shape of the substrate, etc. Therefore, the pre-shaping force is provided by the actuator assembly 720 to shape the substrate 702 into, for example, a flatter shape. Note that during the pre-shaping of the substrate 702, the clamping force holding the substrate to the support pins 710 should be high enough to prevent the substrate from separating from the support pins.

[0061] After pre-shaping the substrate 702, such as Figure 7As shown in (c), the shape of the substrate 702 will better conform to the support surface 704.1 of the support member 704, and the substrate will be positioned or held on the support surface 704.1 of the support member 704. In particular, depending on the number of support pins, the substrate 702 can be pre-shaped to a certain extent. Thus, in the next stage, as Figure 7 As shown in (d), the substrate 702 can be lowered onto the surface 704.1 of the support 704.

[0062] Figure 7 (d) Schematic illustration of a substrate 702 supported on a support 704 when the support pin 710 of the lifting pin assembly 700 has been lowered. Specifically, the support pin 710 has been lowered to a position where the top surface of the support pin is substantially flush with the support surface 704.1 of the support 704. Thus, in the depicted position, the substrate 702 is in contact with both the support pin 710 and the support surface 704.1 of the support 704. Because the substrate 702 is pre-shaped before being lowered onto the support surface 704.1 of the support 704, contact between the substrate 702 and the support 704 can be established with the substrate 702 substantially undeformed. Once lowered onto the support 704, the substrate 702 can be clamped to the support, for example, by a clamping arrangement of the support 704, such as a vacuum or electrostatic clamping assembly. Figure 7 In (d), arrow 730 schematically illustrates the clamping force applied to the substrate 702 by the support 704. Due to the pre-shaping of the substrate, the clamping of the substrate 702 to the support 704 can now be established substantially without the need for deformation of the substrate 702.

[0063] As those skilled in the art will understand, without a pre-shaping action, the substrate 702 will deform when it is lowered onto the support 704. Specifically, when... Figure 7 (b) As the substrate 702 shown is lowered onto the support 704, it will initially contact the support 704 only along its outer edge 702.1 due to its umbrella shape. When the bent or warped substrate 702 is subsequently clamped onto the support 704, the outer edge 702.1 of the substrate will be forced to shift further outward, which may damage the substrate or the support 704.

[0064] Using this invention, the substrate 702 to be loaded or unloaded is pre-shaped before it is supported on the support, thereby avoiding or reducing the risk of deformation of the substrate 702 during the clamping or non-clamping process on the support 704.

[0065] Therefore, damage to the substrate or support can be avoided or mitigated. Furthermore, it facilitates the clamping process where the substrate 702 is transferred from the lifting pin assembly to the support and held by the support rather than by the lifting pin assembly. In particular, it has been observed that when the substrate to be clamped on the support has a curved or non-flat shape, the application of clamping force (e.g., vacuum or electrostatic force) may be impaired or become difficult to apply. In the case of an umbrella-shaped substrate on the support 704, it may be difficult, for example, to attract the central portion of the substrate 702 toward the support. Similarly, in the case of a bowl-shaped substrate on the support 704, it may be difficult, for example, to attract the outer edge of the substrate 702 toward the support 704. This clamping is made easier by the pre-shaping provided by the lifting pin assembly according to the invention.

[0066] According to the present invention, the lifting pin assembly includes a plurality of support pins that can be displaced by an actuator assembly.

[0067] Figure 8 A support pin 800 is schematically shown, which can be applied in a lifting pin assembly according to the invention, the support pin being in a lowered position on the left and in an raised position on the right.

[0068] In the embodiment shown, a tubular support pin 800 is illustrated, which can be connected to a vacuum or low-pressure source, for example, via a supply line 810. In the embodiment shown, the support pin 800 can be moved upwards by an actuator 820. The actuator includes a fixed portion 820.1 and a movable portion 820.2, with the fixed portion 820.1 mounted to a frame 830 and the movable portion 820.2 mounted to the support pin 800. The actuator can be, for example, an electromagnetic actuator, such as a Lorentz actuator or a magnetoresistive actuator. The top of the support pin 800 is configured to provide a support surface 800.1 on which a substrate can be supported. An attractive force can be applied to the supported substrate when needed via a vacuum or low-pressure connection. The actuator 820 shown can be controlled, for example, by a control unit of a lifting pin assembly in which the support pin 800 is applied.

[0069] In one embodiment, multiple support pins (such as support pin 800) are combined and their positions are controlled by a common actuator. Reference Figure 6 The support pin 610a can be mounted, for example, to a common frame, which can then be activated by an actuator (such as...). Figure 8 The actuator 820 shown is shifted.

[0070] In an embodiment, the support pin used in the lifting pin assembly according to the invention includes a compliant portion. In an embodiment, the compliant portion is part of the tip of the support pin. Figure 9A support pin 900 is schematically shown, which can be applied in a lifting pin assembly according to the invention and has a compliant portion.

[0071] Figure 9 Support pin 900 is schematically shown, which is similar to support pin 800, except for the following. (See below.) Figure 9 The support pin 900, schematically shown, includes a conforming portion 910 near the tip of the support pin, which allows for deformation (particularly tilting) of the top of the support pin 900. This tilting is shown on the right side, with the support pin 900 shown in an elevated position. Through the conforming portion 910, the support surface 900.1 of the support pin 900 can be tilted and thus conform to the orientation of the surface of the substrate to be supported. By doing so, the risk of damaging the substrate to be supported is reduced. Due to the more conformal contact, it facilitates clamping of the substrate on the support surface 900.1, thus enabling more successful clamping or holding of the substrate on the support pin 900.

[0072] Instead of a dedicated section with a support pin to incorporate compliance, the support pin, or most of it, can be made of a flexible material to allow for deformation (e.g., tilting) of the top surface of the support pin.

[0073] In an arrangement where multiple support pins are arranged to move via a common actuator, the compliance of the multiple support pins can be integrated into a single unit, such that the top surfaces of the multiple support pins can be oriented toward the bottom surface of the substrate being loaded / unloaded. To produce the desired compliance, one or more leaf springs can be used, for example. Such one or more leaf springs can be applied, for example, to provide compliance with a single support pin or a group of support pins (e.g., a group of support pins that can be displaced by a single actuator).

[0074] Figure 10Another support pin 1000, which can be applied to a lifting pin assembly according to the invention, is schematically shown. The support pin 1000 also includes a conforming portion 1010 that allows the top surface 1000.1 to tilt. The support pin 1000 includes an electrode 1050 through which a clamping force can be applied to a substrate to be loaded / unloaded. In the embodiment shown, the support pin 1000 is movable upward by an actuator 1020. The actuator includes a fixed portion 1020.1 and a movable portion 1020.2, the fixed portion 1020.1 being mounted to a frame 1030 and the movable portion 1020.2 being mounted to the support pin 1000. In the embodiment shown, a position measuring system 1040 is also provided, configured to measure the vertical position of the support pin 1000. In the embodiment shown, the position measurement system 1040 includes a first portion 1040.1 mounted to a support pin 1000 and a second portion 1040.2 mounted to a frame 1030. The first portion 1040.1 may be, for example, a sensor head, while the second portion 1040.2 may be, for example, a scale cooperating with the sensor head. Various position measurement systems can be applied to determine the vertical or Z-position of the support pin. Examples include capacitive systems, encoder-based systems, or interferometer-based systems.

[0075] In embodiments of the invention, the lifting pin assembly therefore includes a position measuring system configured to measure the vertical position of one or more of a plurality of support pins. The position measuring system can provide a position signal to a control unit of the lifting pin assembly. In embodiments of the invention, based on the position signal, the control unit can, for example, determine the shape or deformation of the substrate supported by the support pins. Specifically, during the substrate loading process (e.g., as... Figure 7 (b) As shown, the lifting pin assembly according to the present invention can be configured as follows: The plurality of support pins are shifted toward the bottom surface of the substrate to be loaded, thereby producing, as Figure 7 (b) The situation described, Receive position signals from the position measurement system indicating the vertical position of one or more of the multiple support pins, and The required displacement of multiple support pins is determined based on position signals to pre-shape the substrate.

[0076] Considering Figure 7 The arrangement shown, and assuming each support pin is equipped with a position measuring system, will be understood to allow the control unit to adjust the position based on indications. Figure 7 The position signal shown in (b) determines how to shift the support pin (center pin 710a or outer pin 710b) to achieve the desired effect. Figure 7 The situation depicted in (c) is that the substrate 702 is substantially flat.

[0077] As an alternative to using a position measurement system and determining the required displacement (e.g., to flatten the substrate) based on position signals from said measurement system, the required displacement can be determined based on warp data that the control unit can receive in advance. The substrate may have been conditioned, for example, in a substrate handler, before being loaded onto a substrate support stage, etc. During such conditioning, warp information may have been acquired. This warp information can be applied by the control unit of the lifting pin assembly according to the invention to determine the displacement required to perform pre-shaping of the substrate during the loading / unloading process.

[0078] Regarding the clamping force applied prior to the pre-shaping of the substrate to hold it against the multiple support pins, it can be noted that the applied pre-shaping force for adjusting the shape of the substrate can counteract one or more clamping forces. Consider, for example, Figure 7 (b) The scenario depicted, in which an umbrella-shaped substrate 702 is held on a support pin 710. For pre-shaping the substrate 702, the center pin 710a needs to descend relative to the outer pin 710b. However, due to the rigidity of the substrate, the descent of the center portion of the substrate will generate an upward force on the substrate, counteracting the clamping or holding force. If the clamping force is insufficient, the center portion of the substrate 702 will separate from the pin when the support pin 710a descends. Therefore, compared to known lift-pin assemblies that do not apply substrate pre-shaping, it may be necessary in the lift-pin assembly according to the invention to ensure that the applied clamping force for holding the substrate on the support pin is sufficient to allow for substrate pre-shaping.

[0079] Since the control unit of the lifting pin assembly according to the invention is configured to determine the displacement required to perform pre-shaping, it is also advantageous for the control unit to control the holding force or clamping force.

[0080] Therefore, in embodiments of the present invention, the control unit of the lifting pin assembly can be configured to control the clamping force through which the substrate is held on the support pin.

[0081] The lifting pin assembly according to the invention can be advantageously applied, for example, to a stage (e.g., a stage for holding a semiconductor substrate) in an exposure apparatus (such as a lithography apparatus).

[0082] While the use of lithography equipment in IC manufacturing is specifically referenced in this document, it should be understood that the lithography equipment described herein may have other applications. Possible other applications include the fabrication of integrated optical systems, patterning for guiding and detecting magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, and more.

[0083] Although embodiments of the invention may be specifically referred to herein in the context of lithography equipment, embodiments of the invention can be used in other equipment. Embodiments of the invention can be formed by mask inspection equipment, metrology equipment, or any equipment that measures or processes objects such as wafers (or other substrates) or masks (or other patterning apparatuses). These devices are generally referred to as lithography tools. Such lithography tools can use vacuum conditions or ambient (non-vacuum) conditions.

[0084] Although the use of embodiments of the invention may have been specifically referenced above in the context of optical lithography, it should be understood that the invention is not limited to optical lithography and may be used in other applications, such as imprint lithography, where the context permits.

[0085] Where circumstances permit, embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented by 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 means 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 storage media; optical memory media; flash memory devices; electrical, optical, acoustic, or other forms of propagation signals (e.g., carrier waves, infrared signals, digital signals, etc.), and so on. Furthermore, firmware, software, routines, and instructions may be described in this invention as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and these actions are in fact produced by a computing device, processor, controller, or other means of executing firmware, software, routines, instructions, etc., and performing such operations enables actuators or other devices to interact with the physical world.

[0086] Although specific embodiments of the invention have been described above, it should be understood that the invention can be practiced in ways other than those described. The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the described invention without departing from the scope of the claims set forth below. Other aspects of the invention are set forth in the following numbered clauses. 1. A lifting pin assembly for loading / unloading a substrate, comprising: Multiple support pins, wherein the number of the multiple support pins is more than 3; Actuator assembly, the actuator assembly being configured to cause displacement of the plurality of support pins, and A control unit configured to control the displacement of the plurality of pins to pre-shape the substrate during loading / unloading. 2. The component according to item 1, wherein the plurality of support pins are configured to apply a retaining force on the substrate. 3. The component according to clause 2, wherein the holding force is a vacuum force or an electrostatic force. 4. The component according to clause 2 or 3, wherein the retaining force is applied to the substrate by a subset of the plurality of support pins. 5. The component according to clause 4, wherein the subset includes a pin. 6. The component according to any one of clauses 2 to 5, wherein the control unit is configured to control the holding force. 7. The component according to any one of the preceding clauses further includes a support frame, wherein the plurality of support pins are mounted on the support frame in a displaceable manner. 8. The component according to any one of the preceding clauses, wherein the tips of the plurality of support pins include compliant portions. 9. The component according to item 8, wherein the compliant portion is configured to orient the contact surface of the tip as a contact surface parallel to the substrate. 10. The component according to any one of the preceding clauses, wherein the plurality of support pins comprises a first set of pins and a second set of pins. 11. The component according to clause 10, wherein the first group comprises at least one pin, and wherein the second group comprises at least three pins. 12. The component according to clause 11, wherein each pin in the first set of pins is arranged at a distance D1 from the center of the component, and each pin in the second set of pins is arranged at a distance D2 from the center of the component, where D2 > D1. 13. The component according to clause 11 or clause 12, wherein the first set of pins is arranged on a common frame, and wherein the actuator of the actuator assembly is configured to displace the common frame in a vertical direction. 14. The component according to any one of the preceding clauses further includes a position measuring system configured to measure the vertical position of one or more of the plurality of support pins. 15. The component according to clause 14, wherein the position measurement system includes an encoder-based measurement system. 16. The component according to clause 14 or 15 and referring to clause 2, wherein the control unit is configured to control the retaining force based on the vertical position of one or more of the plurality of pins. 17. The component according to any one of clauses 14 to 16, wherein the control unit is configured to: The plurality of support pins are shifted toward the bottom surface of the substrate to be loaded; Receive position signals from the position measurement system indicating the vertical position of one or more of the plurality of support pins; Based on the position signal, the holding force and displacement for the plurality of support pins are determined to pre-shape the substrate. 18. The assembly according to any of the preceding clauses of reference 2, wherein the retaining force includes a clamping force for clamping the substrate onto the support pins and a pre-shaping force caused by displacement of the plurality of pins to pre-shape the substrate during loading / unloading. 19. The component according to any one of the preceding clauses, wherein pre-shaping the substrate includes reducing the bending or warping of the substrate. 20. A stage comprising a support having a surface for receiving a substrate and a lifting pin assembly according to any one of the preceding clauses. 21. The stage according to clause 20, wherein the control unit of the lifting pin assembly is configured to control the displacement of a plurality of pins to pre-shape the substrate before the substrate contacts the support. 22. An exposure apparatus comprising a stage according to claim 20 or 21.

Claims

1. A lifting pin assembly for loading / unloading a substrate, comprising: Multiple support pins, wherein the number of the multiple support pins is more than 3; Actuator assembly, the actuator assembly being configured to cause displacement of the plurality of support pins, and A control unit configured to control the displacement of the plurality of pins to pre-shape the substrate during loading / unloading.

2. The component of claim 1, wherein the plurality of support pins are configured to apply a retaining force on the substrate.

3. The component according to claim 2, wherein the holding force is a vacuum force or an electrostatic force.

4. The component of claim 2 or 3, wherein the retaining force is applied to the substrate by a subset of the plurality of support pins.

5. The component of claim 4, wherein the subset includes a pin.

6. The component according to any one of claims 2 to 5, wherein the control unit is configured to control the holding force.

7. The component according to any one of the preceding claims further includes a support frame, wherein the plurality of support pins are mounted on the support frame in a displaceable manner.

8. The component according to any one of the preceding claims, wherein the tips of the plurality of support pins include compliant portions.

9. The component of claim 8, wherein the compliant portion is configured to orient the contact surface of the tip as a contact surface parallel to the substrate.

10. The component according to any one of the preceding claims, wherein the plurality of support pins comprises a first set of pins and a second set of pins.

11. The component of claim 10, wherein the first group comprises at least one pin, and wherein the second group comprises at least three pins.

12. The component of claim 11, wherein each pin in the first set of pins is arranged at a distance D1 from the center of the component, and each pin in the second set of pins is arranged at a distance D2 from the center of the component, where D2 > D1.

13. The component according to any one of the preceding claims further includes a position measuring system configured to measure the vertical position of one or more of the plurality of support pins.

14. The component of claim 13 and referring to claim 2, wherein the control unit is configured to control the retaining force based on the vertical position of one or more of the plurality of pins.

15. The component of claim 13 or 14, wherein the control unit is configured to: The plurality of support pins are shifted toward the bottom surface of the substrate to be loaded; The position measurement system receives a position signal indicating the vertical position of one or more of the plurality of support pins; Based on the position signal, the holding force and displacement for the plurality of support pins are determined to pre-shape the substrate.

16. The component according to any of the preceding claims of claim 2, wherein the retaining force comprises a clamping force for clamping the substrate onto the support pins and a pre-shaping force caused by displacement of the plurality of pins to pre-shape the substrate during loading / unloading.

17. The component according to any one of the preceding claims, wherein pre-shaping the substrate includes reducing the bending or warping of the substrate.

18. A stage comprising a support having a surface for receiving a substrate and a lifting pin assembly according to any one of the preceding claims.

19. The stage of claim 18, wherein the control unit of the lifting pin assembly is configured to control the displacement of the plurality of pins to pre-shape the substrate before the substrate contacts the support.

20. An exposure apparatus comprising a stage according to claim 18 or 19.

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