System and method for aligning substrates

Abstract

This disclosure provides a system and method for aligning a substrate. The system includes a vertically movable rotatable support unit and an alignment support located at the same location as the rotatable support unit. Optionally, the alignment support unit surrounds the rotatable support unit at least partially.

Description

Technical Field

[0001]

[0001] This application claims priority from European Application No. 23162524.5 filed on March 17, 2023 and European Application No. 23167034.0 filed on April 6, 2023, the entire contents of which are incorporated herein by reference.

[0002]

[0002] The present invention relates to a system and method for aligning substrates. The system can be regarded as a component for correcting the position within the range of the size of the substrate. The centering of the substrate can be, for example, a process as part of a substrate handler or stage in an exposure apparatus, a metrology tool, or an inspection tool. The substrate can be a wafer, a mask, or a reticle as used in a lithography process and / or a lithography apparatus.

Background Art

[0003]

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

[0004]

[0004] As semiconductor manufacturing processes continue to evolve, the dimensions of circuit elements have continuously decreased, while the amount of functional elements such as transistors per device has steadily increased over decades, following a trend commonly known as Moore's Law. To keep up with Moore's Law, the semiconductor industry is pursuing technologies that enable the creation of increasingly smaller features. To project patterns onto a substrate, lithography equipment can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. To form features smaller on a substrate than those produced by a lithography equipment using radiation with a wavelength of 193 nm, for example, a lithography equipment using extreme ultraviolet (EUV) radiation with wavelengths in the range of 4 nm to 20 nm, for example, 6.7 nm or 13.5 nm, may be used.

[0005]

[0005] During the lithography process, multiple patterned layers typically need to be irradiated and deposited on the same substrate. In this specification, the substrate (such as a wafer) typically needs to be moved multiple times from a storage location to an irradiation location within the lithography apparatus. The lithography apparatus typically includes one or more dedicated substrate handlers to ensure that the substrate is moved with the required precision.

[0006]

[0006] In a typical lithography setup, the substrate is transported to the substrate table of the lithography projector by a substrate track and a substrate handler. On the substrate track, the surface of the substrate is pre-treated. Substrate pre-treatment may typically include covering the substrate at least partially with a layer of radiation-sensitive material (resist). In addition, various other pre-treatment procedures such as priming, soft baking, or thermal adjustment may be performed on the substrate before the imaging step. After substrate pre-treatment, the substrate is transported from the substrate track to the substrate stage via a substrate handler. The substrate handler is typically adapted to precisely position the substrate on the substrate table of the substrate stage and may also control the temperature of the substrate.

[0007]

[0007] Accordingly, the loading and unloading of wafers onto the wafer table of the lithography machine is supported by a wafer handling (WH) unit. This unit typically includes a pre-alignment (PA) and adjustment unit (adjustment as herein may include temperature stabilization) that aligns and adjusts the wafer before transferring it. Pre-alignment ensures that wafer eccentricity is limited and that the substrate temperature profile is substantially uniform.

[0008]

[0008] US-7307695-B2 describes a method and device for aligning a substrate. This device includes a (pre)alignment support located near the edge of the substrate.

[0009]

[0009] US-2019 / 0390335 discloses an aligner for a substrate. The aligner is configured to perform a centering operation by moving and rotating a centering stage until the center of the substrate on the centering stage is aligned with the axis of the process stage. The aligner is configured to calculate the distance to move the centering stage and the angle to rotate the centering stage based on the initial relative position, eccentricity, and direction of eccentricity of the axis of the centering stage with respect to the axis of the process stage.

[0010]

[0010] US-1118512-B2 discloses a stocker including an aligner configured to align wafers. The aligner includes a rotating member configured to support and rotate a wafer to align the wafer. Centering members are positioned radially with respect to the rotating member, and each centering member is movable toward the rotating member and configured to move a wafer positioned on the rotating member so that the center of the wafer is aligned with the center of the rotating member.

[0011]

[0011] CN-104111595-A discloses a pre-alignment device used in lithography equipment. This device includes a centering unit used to correct the eccentricity of a silicon chip by placing the silicon chip on it and performing linear movement; an orientation unit used to rotate the silicon chip and determine the gap position of the silicon chip; an image acquisition unit used to acquire information on the edges and gaps of the silicon chip; and a data processing unit used to process the acquired information and remove interference information within the acquired information. The present invention also discloses a pre-alignment method used in lithography equipment.

[0012]

[0012] Processing layers on a wafer can generate stress, which can lead to wafer warping. In the case of bowl-shaped wafers, the edges may be too far from the centering unit. As described above, current pre-alignment (PA) and adjustment units are unable to handle heavily warped wafers, thus limiting their processing capacity. In this specification, the definition of a heavily warped substrate may vary depending on the application, but for example, it may mean a height difference of more than approximately 500 μm on the top surface of the substrate. Typically, with warped substrates, conventional pre-alignment units can only operate if thermal adjustment (such as air bearings) is active. A solution is to perform centering using a gripper, also known as an end effector, instead of a centering unit, but this is less accurate and significantly slower, resulting in a loss of throughput.

[0013]

[0013] The object of this disclosure is to provide an improved pre-alignment system and method. [Overview of the project]

[0014]

[0014] This disclosure provides, A system for aligning circuit boards, A rotatable support unit that can move vertically along its longitudinal axis, Alignment support located in the same place as the rotatable support unit, A system including this is provided.

[0015]

[0015] In one embodiment, the alignment support surrounds the rotatable support unit at least partially. The alignment support may surround the rotatable support unit in the circumferential direction.

[0016]

[0016] In one embodiment, the alignment support is operably detached from the rotatable support unit.

[0017]

[0017] In one embodiment, the alignment support is movable vertically and horizontally with respect to the rotatable support unit.

[0018]

[0018] The alignment support may be positioned at a horizontal distance from the rotatable support unit. The horizontal distance may extend in the circumferential direction. The horizontal distance can be approximately 0.5 to 2 cm.

[0019]

[0019] In one embodiment, the alignment support has an upper end with at least three projections for supporting the substrate. The at least three projections may together form at least a portion of a circle.

[0020]

[0020] A suction unit for clamping a substrate may be provided at the upper end of the rotatable support unit.

[0021]

[0021] In one embodiment, the system further includes a support table for supporting a substrate and having a centrally located opening, the rotatable support unit being vertically movable through the centrally located opening.

[0022]

[0022] In one embodiment, the support table includes a thermal control unit.

[0023] According to another aspect, provided by the present disclosure, A method for aligning a substrate, comprising: Supporting the substrate on a rotatable support unit; Moving the rotatable support unit vertically along its longitudinal axis to lift and rotate the substrate to a predetermined orientation; Retracting the rotatable support unit; Moving an alignment support arranged at the same location as the rotatable support unit vertically with respect to the rotatable support unit to laterally move the substrate with respect to the rotatable support unit. A method is provided that includes the above steps.

[0024] In one embodiment, the alignment support at least partially surrounds the rotatable support unit. The alignment support may be arranged at a mutual horizontal distance with respect to the rotatable support unit.

[0025] In one embodiment, the alignment support is operably disconnected from the rotatable support unit.

[0026] According to yet another aspect, provided by the present disclosure, a method for aligning a substrate, comprising: supporting the substrate on a substrate table having a centrally located opening; moving a rotatable support unit vertically through the opening located at the center of the support table to lift and rotate the substrate to a predetermined orientation; retracting the rotatable support unit; and moving an alignment support arranged at the same location as the rotatable support unit vertically with respect to the rotatable support unit to laterally move the substrate with respect to the rotatable support unit. A method is provided that includes the above steps.

[0027]

[0027] In one embodiment, the alignment support at least partially surrounds the rotatable support unit. The alignment support may be arranged at a mutual horizontal distance from the rotatable support unit.

[0028]

[0028] In one embodiment, the alignment support is operably disconnected from the rotatable support unit.

[0029]

[0029] According to yet another aspect, there is provided a lithography apparatus including at least one of the above-described systems according to the present disclosure.

[0030]

[0030] According to another aspect, there is provided the use of the above-described system in one or more of a metrology tool, an exposure apparatus, a lithography apparatus, and a substrate handler according to the present disclosure.

Brief Description of the Drawings

[0031]

[0031] Some embodiments of the present invention will be described below by way of example only, with reference to the accompanying schematic drawings.

[0032] [Figure 1] Shows a schematic appearance of a lithography apparatus. [Figure 2] Is a cross-sectional side view of an alignment system. [Figure 3] Is a cross-sectional side view of an embodiment of the system of the present disclosure. [Figure 4] Is a cross-sectional side view of a further embodiment of the system of the present disclosure. [Figure 5] Is a perspective view of an embodiment of the system of the present disclosure. [Figure 6] Is a perspective view of a further embodiment of the system of the present disclosure. [Figure 7A] Is a cross-sectional side view of a given step of an embodiment of the method according to the present disclosure. [Figure 7B] Is a cross-sectional side view of a given step of an embodiment of the method according to the present disclosure. [Figure 7C]This is a cross-sectional side view of a given step of one embodiment of the method relating to this disclosure. [Figure 7D] This is a cross-sectional side view of a given step of one embodiment of the method relating to this disclosure. [Figure 8A] This is a cross-sectional side view of a given step of a further embodiment of the method relating to this disclosure. [Figure 8B] This is a cross-sectional side view of a given step of a further embodiment of the method relating to this disclosure. [Figure 8C] This is a cross-sectional side view of a given step of a further embodiment of the method relating to this disclosure. [Figure 8D] This is a cross-sectional side view of a given step of a further embodiment of the method relating to this disclosure. [Modes for carrying out the invention]

[0033]

[0032] In this specification, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation. Radiation may include ultraviolet (e.g., having wavelengths of 365, 248, 193, 157 or 126 nm) and EUV (e.g., extreme ultraviolet radiation having wavelengths in the range of about 5 to 100 nm).

[0034]

[0033] As used herein, the terms “reticle,” “mask,” or “patterning device” can be broadly interpreted to refer to a general patterning device that can be used to impart a patterned cross section to an incident radiation beam, corresponding to a pattern to be created on a target portion of a substrate. The term “light bulb” can also be used in this context. In addition to typical masks (transmissive or reflective, binary, phase-shifted, hybrid, etc.), other examples of such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0035]

[0034] Figure 1 schematically shows a lithography apparatus LA. The lithography apparatus LA includes an illumination system (also called an illuminator) IL configured to adjust a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation), a mask support (e.g., a mask table) MT connected to a first positioner PM constructed to support a patterning device (e.g., a mask) MA and configured to precisely position the patterning device MA according to specific parameters, a substrate support (e.g., a wafer table) WT connected to a second positioner PW constructed to hold a substrate (e.g., a resist-coated wafer) W and configured to precisely position the substrate support according to specific parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project the pattern applied to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g., including one or more dies).

[0036]

[0035] During operation, the illumination system IL receives the radiant beam from the radiation source SO, for example, via the beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for directing, shaping, and / or controlling the radiation. By adjusting the radiant beam B using the illuminator IL, the cross-section of the radiant beam can be given the desired spatial and angular intensity distribution in the plane of the patterning device MA.

[0037]

[0036] The term “projection system” PS as used herein should be broadly interpreted to encompass a variety of projection systems, including refractive, reflective, reflective-refracting, anamorphic, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, that are appropriate for the exposure radiation used and / or for other factors such as the use of immersion liquid or vacuum. All use of the term “projection lens” as used herein should be considered synonymous with the more general term “projection system” PS.

[0038]

[0037] The lithography apparatus LA may be of a type that can cover at least a portion of the substrate with a liquid having a relatively high refractive index (e.g., water) to fill the space between the projection system PS and the substrate W, which is also called immersion lithography. More detailed information on immersion technology is described in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0039]

[0038] The lithography apparatus LA may be of a type having two or more substrate support WTs (also called "dual stages"). In such a "multistage" machine, multiple substrate support WTs may be used in parallel, and / or steps in preparing the substrate W for subsequent exposure may be performed on the substrate W located on one of the substrate support WTs, while a pattern may be exposed on the other substrate W using another substrate W on another substrate support WT.

[0040]

[0039] In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is positioned to hold sensors and / or cleaning devices. The sensors may be positioned 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 positioned to clean parts of the lithography apparatus, for example, parts of the projection system PS or parts of the system that provides the immersion fluid. When the substrate support WT is away from the projection system PS, the measurement stage may be moved below the projection system PS.

[0041]

[0040] During operation, the radiating beam B is incident on a patterning device (e.g., mask MA) held on a mask support MT, and a pattern (design layout) is formed by the pattern on the patterning device MA. After passing through the mask MA, the radiating beam B passes through a projection system PS, which focuses the beam onto a target portion C on the substrate W. A second positioner PW and a position measuring system IF can be used to precisely move the substrate support WT to position various target portions C within the path of the radiating beam B at a focused and aligned position, for example. Similarly, a first positioner PM and optionally another position sensor (not shown in Figure 1) can be used to precisely position the patterning device MA relative to the path of the radiating beam B. The patterning device MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. In the example, the substrate alignment marks P1 and P2 occupy dedicated target areas, but the substrate alignment marks P1 and P2 can also be placed in the space between target areas. When the substrate alignment marks P1 and P2 are positioned between target areas C, they are known as scribe line alignment marks.

[0042]

[0041] To clarify the present invention, the Cartesian coordinate system is used. The Cartesian coordinate system has three axes, namely the x-axis, y-axis, and z-axis. Each of the three axes is orthogonal to the other two axes. A rotation about the x-axis is called the Rx-rotation. A rotation about the y-axis is called the Ry-rotation. A rotation about the z-axis is called the Rz-rotation. The x-axis and y-axis define the horizontal plane, while the z-axis is perpendicular. The Cartesian coordinate system is used for clarification purposes only and is not intended to limit the present invention. The present invention may be clarified using another coordinate system, such as the cylindrical coordinate system, instead of the Cartesian coordinate system. The Cartesian coordinate system may have different orientations, for example, such that the z-axis has a component along the horizontal plane.

[0043]

[0042] Figure 2 shows a system 10 for aligning a substrate W. The system includes a support table 12 for supporting the substrate. The table has a centrally located opening 14. A rotatable support unit 16 is vertically movable through the centrally located opening 14 of the support table 14. The table is provided with at least one second opening 18. An alignment support 20 extends at least partially through the second opening 18 and is radially movable relative to the rotatable unit 16. An edge support unit 22 including a sensor 24 may be provided. The sensor may be a CCD camera or an equivalent optical sensor.

[0044]

[0043] Openings 26 and 28 may be provided on the upper surface of the support table 12. The openings 26 and 28 may be connected to pumps, respectively, to allow gas discharge and gas intake. The first opening 26 is connected to a first pump 30 that discharges air through the opening, which can generate an air bearing that allows the substrate to float on the support table. The second opening 28 is connected to a second pump 32 for drawing in air or gas, which can use the pressure drop to fix the substrate to the support table 12. The air bearing generated by the air discharged from the opening 26 makes it possible to rotate and adjust the wafer W while it is clamped (for example, by the vacuum generated by the opening 28).

[0045]

[0044] During use, the substrate W is rotated while measuring the edges using the optical sensor 24. In this specification, the edges of the substrate are usually provided with characteristic features such as notches, which enable rough positioning based on optical detection. The wafer alignment (x, y, Rz) can be calculated and corrected using the information provided by the optical sensor 24. The pre-aligner in the wafer handler may have a measurement accuracy of several micrometers. The centering unit 20 moves the wafer radially. The centering unit may have an accuracy of several tens of micrometers. Next, any alignment residue can be measured via the edge scanning unit 22 and eliminated at the wafer stage level. After measurement, the substrate W can be rotated using the rotatable unit 16 so that the notches are positioned in a predetermined orientation.

[0046]

[0045] Numerous commercially available pre-alignment units are sold by several companies, including Kensington Laboratories, LLC [USA] and Wafer-Handling.com [USA, California].

[0047]

[0046] In practical embodiments, the pre-aligner provides high-precision measurement (several μm), which enables the loading of the substrate into the lithography apparatus LA within the range of the wafer stage positioning system. In other words, accurate orientation in the wafer handler limits errors in the wafer stage, thereby improving throughput. Optionally, the support table 12 may include a thermal stabilization unit (TSU). The latter makes it possible to set a temperature profile of the substrate (typically a substantially uniform temperature across the entire substrate) during pre-alignment.

[0048]

[0047] The main drawback of the design in Figure 2 is its limited ability to handle warped wafers. A substrate can have a height difference of approximately 350 μm, and up to 500 μm, between the highest and lowest points of its top surface (i.e., warp). In general, it is difficult to clamp a substrate with a height difference of more than 500 μm. With additional tricks, it may be possible to clamp a substrate with a warp of up to 700 μm. However, in practice, a substrate may warp up to 1 mm, and the roadmap for future substrate specifications will extend this to 1.3 mm. A warped substrate needs to be introduced into an air bearing and floated, typically at a distance of several tens of μm, from the surface of the support table 12. Bowl-shaped wafers are particularly difficult to clamp. Bowl-shaped and umbrella-shaped substrates may come into contact with the support table while being flattened and clamped. State-of-the-art hardware can clamp a substrate with a warp of up to 500 μm. Wafers with warping exceeding this maximum value are typically rejected, leading to the cancellation of many jobs and thus a decrease in yield. It should be noted that warped wafers are rotatable and measurable when not clamped to air bearings. However, the centering unit 20 can only move the wafer when it is supported by air bearings.

[0049]

[0048] Referring to Figure 3 in whole, an embodiment of the system 40 of the present disclosure includes a rotatable support unit 44 that is movable vertically along its longitudinal axis. An alignment support 46 is located in the same place as the rotatable support unit 44. Located in the same place should be understood as sharing a space. As shown in the cross-sectional view in Figure 3, the alignment support 46 is positioned at least partially around the rotatable support unit 44, thereby at least partially surrounding it. During operation, the alignment support 46 and the rotatable support unit 44 may be separated, and thus the two can be operably separated.

[0050]

[0049] The rotatable support unit 44 may be a vertically movable telescopic support unit, for example, by applying overpressure or underpressure via a pneumatic line, with or without additional air passages for removing contaminants. An advantage of the telescopic support unit is that calibration can be performed by raising the upper surface of the support unit to a predetermined level and sensing or detecting the telescopic support unit, for example, via one or more sensors placed on one or more end effectors, or via a detection signal in a controller.

[0051]

[0050] In one embodiment, the alignment support 46 includes a cylindrical portion 48, which is shown in Figure 5. The first cylindrical portion 48 at least partially surrounds the second cylindrical portion 50 of the rotatable support unit 44. The cylindrical portion 48 of the alignment support at least partially surrounds the cylindrical portion 50 of the rotatable support unit, preferably in the circumferential direction. The cylindrical portion 50 of the rotatable support unit can move along its longitudinal axis and also perpendicular to the cylindrical portion 48 of the alignment support unit 46. The alignment support 46 is movable perpendicular and horizontally with respect to the rotatable support unit 44.

[0052]

[0051] In one embodiment, the alignment support is positioned at a horizontal distance from the rotatable support unit. In particular, the cylindrical portion 48 may be positioned at a lateral or radial distance from the cylindrical portion 50 of the rotatable support unit. The lateral or radial distance, i.e., the distance along the horizontal plane, may be about 0.5 to 5 cm, for example, about 1 cm. For example, the radial distance may be between the first cylinder 48 and the second cylinder 50, so that the first cylinder 48 can also move horizontally relative to the second cylinder within the range set by the radial distance. The relative horizontal distance may extend in the circumferential direction. The relative horizontal distance may be about 0.5 to 2 cm.

[0053]

[0052] The alignment support 46, typically, may have an upper end portion of its cylindrical section 48 that includes at least three projections 52 for supporting the substrate W. This is shown in Figure 6. The at least three projections 52 together may form at least a portion of a circle.

[0054]

[0053] The upper end 54 of the rotatable support unit 44 may be provided with a suction unit (not shown) for clamping the substrate. The suction unit in this specification may typically include an opening for gas connected to a third pump. The pump can reduce the pressure by drawing in air or gas, thereby reducing the pressure between the opening and the substrate, which in turn clamps the substrate to the upper end 54 of the rotatable support 44. In place of the vacuum clamping mechanism described above, other suitable clamping mechanisms such as electrostatic clamps may be provided.

[0055]

[0054] In the above embodiment shown overall in Figure 3, the centering of the substrate is completely isolated from the substrate support table and temperature control unit. Therefore, the substrate can be separately aligned for any adjustment process in preparation for subsequent processing steps, such as a lithography process.

[0056]

[0055] Referring to Figure 4 in general, in embodiments of the present disclosure, the system 40 further includes a support table 12 having a centrally located opening 42 for supporting the substrate W. A rotatable support unit 44 is movable vertically along its longitudinal axis through the centrally located opening 42. As described in the prior embodiments in relation to Figure 3, an alignment support 46 is located in the same place as the rotatable support unit and is also positioned to move through the centrally located opening 42 of the support table 12 to enable alignment of the substrate W.

[0057]

[0056] As shown in the cross-sectional view in Figure 4, the alignment support 46 is positioned at least partially around the rotatable support unit 44, thereby at least partially surrounding the rotatable support unit. During operation, the alignment support 46 and the rotatable support unit 44 may be separated, and thus the two can be operably separated.

[0058]

[0057] In one embodiment, the rotatable support unit 44 may be a telescopic support unit as described above.

[0059]

[0058] In one embodiment, the alignment support 46 includes a cylindrical portion 48 (see Figure 5) extending through a central opening. The first cylindrical portion 48 at least partially surrounds the second cylindrical portion 50 of the rotatable support unit 44, which also extends through the same opening 42 of the support table 12. The cylindrical portion 48 of the alignment support at least partially surrounds, preferably circumferentially, the cylindrical portion 50 of the rotatable support unit. The cylindrical portion 50 of the rotatable support unit is movable vertically relative to the support table 12 and relative to the cylindrical portion 48 of the alignment support unit 46. The alignment support 46 is movable vertically and horizontally relative to the rotatable support unit 44.

[0060]

[0059] In one embodiment, the alignment support is positioned at a horizontal distance from the rotatable support unit. In particular, the cylindrical portion 48 may be positioned at a lateral or radial distance from the cylindrical portion 50 of the rotatable support unit. The lateral or radial distance, i.e., the distance along the horizontal plane, may be about 0.5 to 5 cm, for example, about 1 cm. For example, the radial distance may be between the first cylinder 48 and the second cylinder 50, so that the first cylinder 48 can also move horizontally relative to the second cylinder within the range set by the radial distance. The relative horizontal distance may extend in the circumferential direction. The relative horizontal distance may be about 0.5 to 2 cm.

[0061]

[0060] The alignment support 46, typically, may have an upper end portion of its cylindrical section 48 that includes at least three projections 52 for supporting the substrate W. This is shown in Figure 6. The at least three projections 52 together may form at least a portion of a circle.

[0062]

[0061] The upper end 54 of the rotatable support unit 44 may be provided with a suction unit (not shown) for clamping the substrate. The suction unit in this specification may typically include an opening for gas connected to a third pump. The pump can reduce the pressure by drawing in air or gas, thereby reducing the pressure between the opening and the substrate, which in turn clamps the substrate to the upper end 54 of the rotatable support 44. In place of the vacuum clamping mechanism described above, other suitable clamping mechanisms such as electrostatic clamps may be provided.

[0063]

[0062] Optionally, the substrate table 12 may include a thermal control unit. In such an embodiment, the system of the disclosure makes it possible to adjust the temperature profile of the substrate while positioning the substrate and preparing it for subsequent processing steps in a lithography process, for example.

[0064]

[0063] The cylindrical portions 48 and 50 of the alignment unit 46 and the rotation unit 44 can be connected to encoder motors 60 and 62, respectively. Because the lithography process requires micrometer-level precision, the encoder motors 60 and 62 are relatively large. As a result, it is relatively difficult to place the alignment and rotation functions in the same location. In one embodiment, the first encoder 62 of the rotatable support unit 44 is relatively bulky. The second encoder 60 can be positioned on top of the first encoder 62 or attached to one of its sides. The alignment unit 44 may include an arm 64 connected to the cylindrical portion 48. The second encoder 60 can move the cylindrical portion both vertically and in one or more horizontal directions by moving the arm 64.

[0065]

[0064] The specific examples described herein relate to cylindrical features, namely cylindrical rotation units and corresponding cylindrical alignment / centering units, but it will be understood that the disclosure herein is not limited to such shapes. Any functional shape, including substantially rectangular parallelepipeds, may be used for embodiments of the present invention.

[0066]

[0065] Referring to Figures 7A to 7D in general, the method for aligning a substrate according to the present disclosure may include the step of supporting the substrate W on either a rotatable support unit 44 or an alignment support 46. The support of the substrate W by this embodiment of the method is independent of and therefore isolated from a support table or adjustment unit. In the first step (see Figure 7A), the alignment unit 44 is in a lowered position, where its upper surface is away from the substrate.

[0067]

[0066] The rotating unit 44 rotates the substrate W to a predetermined orientation. This step may involve edge measurement using a sensor 24 (not shown), as described above. Rotating the substrate allows for the identification of the substrate's eccentricity.

[0068]

[0067] Next, as shown in Figure 7B, the alignment support unit 46 moves upward, i.e., vertically along its longitudinal axis, until its upper end engages with the substrate W. In this specification, the upper end (or a plurality of upper ends) of the alignment unit may each be provided with a vacuum opening for clamping the substrate, or other suitable alternative clamping means such as an electrostatic clamp.

[0069]

[0068] When the alignment unit 46 is suitably engaged with the substrate W, the alignment unit moves the substrate W horizontally in a plane, i.e., laterally, relative to the rotatable unit 44, and corrects the eccentricity of the substrate within a set range and accuracy. See Figure 7C.

[0070]

[0069] Next, as shown in Figure 7D, the alignment unit 46 is lowered relative to the rotatable unit 44. If necessary, the rotation (also called orientation) of the substrate can be corrected by the rotation of the rotatable unit 44.

[0071]

[0070] Finally, the system of the present disclosure can transfer the substrate W to a subsequent step or unit in the lithography process. Transferring the substrate W may require a gripper or end effector to reposition the substrate.

[0072]

[0071] Accordingly, the method of the present disclosure may include moving a rotatable support unit vertically along its longitudinal axis to lift the substrate and rotate it to a predetermined orientation. Optionally, the method may include retracting the rotatable support unit. The method then includes moving an alignment support, located in the same location as the rotatable support unit, vertically relative to the rotatable support unit, and then enabling the substrate to be moved horizontally, for example, radially, relative to the rotatable support unit.

[0073]

[0072] Referring to Figures 8A to 8D in general, the method for aligning a substrate according to the present disclosure may include the step of supporting the substrate W on a support table 12. In the first step, as shown in Figure 8A, the alignment unit 44 is in a lowered position, where its upper surface is away from the substrate. Typically, an air bearing 26 and / or a vacuum clamping unit 28 may be actuated.

[0074]

[0073] While the substrate is floating on the air bearing 26, the rotating unit 44 rotates the substrate W in a predetermined orientation. This step may involve edge measurement using the sensor 24, as described above.

[0075]

[0074] Next, as shown in Figure 8B, the alignment support unit 46 moves upward relative to the support table until its upper end engages with the substrate W. In this specification, the upper end (or multiple upper ends) of the alignment unit may each be provided with a vacuum opening for clamping the substrate. It will be understood that other suitable clamping mechanisms, such as electrostatic clamps, may also be provided.

[0076]

[0075] When the alignment unit 46 is suitably engaged with the substrate W, the alignment unit moves the substrate W horizontally, i.e., radially, in a plane relative to the rotatable unit 44, correcting the eccentricity of the substrate within a set range and accuracy. See Figure 8C.

[0077]

[0076] Next, as shown in Figure 8D, the alignment unit 46 is lowered relative to the rotatable unit 44. If necessary, the rotation (also called orientation) of the substrate can be corrected by the rotation of the rotatable unit 44.

[0078]

[0077] Finally, the system of the present disclosure can transfer the substrate W to a subsequent step or unit in the lithography process.

[0079]

[0078] Accordingly, the method of the present disclosure may include moving a rotatable support unit vertically through an opening located in the center of a support table to lift the substrate and rotate it to a predetermined orientation. Optionally, the method may include retracting the rotatable support unit. The method then includes moving an alignment support vertically, which is located in the same place as the rotatable support unit and is operably detached from the rotatable support unit, to enable the substrate to be moved horizontally, for example, radially, relative to the rotatable support unit.

[0080]

[0079] During pre-alignment by any of the above methods, the rotating unit clamps and rotates the substrate to be aligned, thereby rotating the substrate. During this rotation, a separate sensor 24 (such as a CCD camera) may scan the edges of the substrate during rotation to identify eccentricity. The rotating unit 44 then releases the substrate, and the centering unit 46 clamps the substrate and moves the substrate and TSU relative to each other to correct the measured eccentricity. The substrate handler is designed to position the substrate within a preset threshold on a target location such as a wafer table. The position thresholds herein are typically related to rotation and eccentricity.

[0081]

[0080] The centering unit design of the present disclosure includes a centering unit that, when a support table is present, is positioned at the same location as the rotatable unit in the center of the support table. Such a support table may be an adjustment unit such as a thermal stabilization unit (TSU). Since this arrangement may be used separately from adjustments based on air bearings, any support table may be used, or no support table may be used. Embodiments of the present invention without a support table have been described. As an example, a bar table may be used for adjustment, in which case alignment and adjustment are usually performed sequentially. When an air bearing table is used, alignment and adjustment can be performed in parallel. In the system according to the embodiment of the present disclosure, the centering unit and the rotatable unit are positioned at the same location but can operate independently.

[0082]

[0081] The centering unit of the present invention can handle highly warped wafers because the local angle of warping is minimized at its center. At the center, the substrate is relatively flat. The centering unit and the rotating unit engage with the substrate only at the center. Further advantages include a high-precision encoder on the centering unit for more accurate measurement. The system may include a leaf spring mechanism for faster operation.

[0083]

[0082] In actual embodiments, the systems of the present disclosure can handle substrates having a warp of more than 1000 μm up to 2000 μm or more. In this specification, since the substrate is substantially flat in the center, the alignment unit and the rotation unit can accurately position substantially any substrate.

[0084]

[0083] The systems and methods of the present disclosure can be used, for example, in one or more of the following: a metrologic tool, an exposure apparatus, a lithography apparatus, and a substrate handler.

[0085]

[0084] While this specification provides specific references to the use of lithography equipment in IC manufacturing, it should be understood that the lithography equipment described herein may have other applications. Other possible applications include the manufacture of integrated optical systems, guidance patterns and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, and the like.

[0086]

[0085] While this specification provides specific references to embodiments of the present invention in relation to lithography apparatus, embodiments of the present invention may be used in other apparatuses. Embodiments of the present invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus for measuring or processing objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatuses are sometimes commonly referred to as lithography tools. Such lithography tools may operate under vacuum conditions or environmental (non-vacuum) conditions.

[0087]

[0086] Although specific references have been made above regarding the use of embodiments of the present invention in relation to photolithography, it is clear that the present invention is not limited to photolithography, where circumstances permit, and may also be used in other applications, such as imprint lithography.

[0088]

[0087] Where circumstances permit, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored in a machine-readable medium and 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 computer device). For example, a machine-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic storage media, optical storage media, flash memory devices, electrical, optical, sound, or other forms of propagating signals (e.g., carrier waves, infrared signals, digital signals, etc.). Furthermore, in this specification, firmware, software, routines, and instructions may be described as performing some kind of operation. However, such descriptions are merely for convenience, and it should be understood that such operation is actually performed by a computer device, processor, controller, or other device that executes the firmware, software, routines, instructions, etc., thereby enabling the actuator or other device to interact with the material world.

[0089]

[0088] Although specific embodiments of the present invention have been described above, it is clear that the present invention can be implemented in forms other than those described above. The above description is intended to be illustrative and not limiting. Accordingly, it will be clear to those skilled in the art that the present invention can be modified as described above without departing from the scope of the claims described below.

Claims

1. A system for aligning circuit boards, A rotatable support unit that can move vertically along its longitudinal axis, An alignment support located in the same place as the aforementioned rotatable support unit, A system that includes this.

2. The system according to claim 1, wherein the alignment support at least partially surrounds the rotatable support unit, and / or surrounds the rotatable support unit in the circumferential direction, and / or is operably detached from the rotatable support unit, and / or is movable vertically and horizontally with respect to the rotatable support unit, and / or is positioned at a relative horizontal distance from the rotatable support unit, preferably the relative horizontal distance extends in the circumferential direction, or preferably the relative horizontal distance is about 0.5 to 2 cm.

3. The alignment support has an upper end portion provided with at least three projections for supporting the substrate, preferably the at least three projections together form at least a portion of a circle, according to claim 1 or 2.

4. The upper end of the rotatable support unit is provided with a suction unit for clamping the substrate and / or further includes a support table for supporting the substrate and having a centrally located opening, wherein the rotatable support unit is movable vertically through the centrally located opening, and preferably the support table includes a thermal control unit, according to any one of claims 1 to 3.

5. A method for aligning a circuit board, The steps include supporting the substrate on a rotatable support unit, The steps include moving the rotatable support unit vertically along its longitudinal axis to lift the substrate and rotate it to a predetermined orientation, The steps include: retracting the rotatable support unit, The steps include moving the alignment support, which is located at the same location as the rotatable support unit, vertically relative to the rotatable support unit, thereby moving the substrate laterally relative to the rotatable support unit, Methods that include...

6. The method according to claim 5, wherein the alignment support at least partially surrounds the rotatable support unit, and / or the alignment support is positioned at a horizontal distance from the rotatable support unit, and / or the alignment support is operably detached from the rotatable support unit.

7. A method for aligning a circuit board, The steps include supporting the substrate on a substrate table having a centrally located opening, The steps include moving the rotatable support unit vertically through the opening located in the center of the support table to lift the substrate and rotate it in a predetermined orientation, The steps include: retracting the rotatable support unit, The steps include moving the alignment support, which is located at the same location as the rotatable support unit, vertically relative to the rotatable support unit, thereby moving the substrate laterally relative to the rotatable support unit, Methods that include...

8. The method according to claim 7, wherein the alignment support at least partially surrounds the rotatable support unit, and / or the alignment support is positioned at a horizontal distance from the rotatable support unit, and / or the alignment support is operably detached from the rotatable support unit.

9. A lithography apparatus comprising at least one system according to any one of claims 1 to 4.

10. Use of the system according to any one of claims 1 to 4 in one or more of the metronidatory tool, exposure apparatus, lithography apparatus, and substrate handler.

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