Method of operating an electrostatic clamp and electrostatic clamp

Abstract

An electrostatic clamp and a method of operating the same. The method of operating the electrostatic clamp includes: applying a voltage to an electrode layer of the electrostatic clamp, the electrode layer including: a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the first electrode, the second electrode, the third electrode, and the fourth electrode are in a first polarization state; switching the second electrode and the third electrode to a second polarization state opposite to the first polarization state; and switching the first electrode and the fourth electrode to the second polarization state opposite to the first polarization state.

Description

Technical Field

[0001] This disclosure relates to electrostatic fixtures and methods for operating electrostatic fixtures in lithography processes. Background Technology

[0002] In the semiconductor integrated circuit industry, advancements in materials and technology have led to several generations of integrated circuits, each with smaller and more complex circuits than its predecessor. The development of integrated circuits has generally increased functional density (i.e., the number of interconnecting elements per unit area) while reducing geometric dimensions (i.e., the smallest components or wiring that can be produced using manufacturing processes). This scaling down process largely benefits production efficiency and reduces associated costs. However, such scaling down also increases the complexity of integrated circuit handling and manufacturing.

[0003] Lithography processes are used to pattern photoresist layers in various patterning processes (e.g., etching or ion implantation). In a typical lithography process, a photosensitive layer (photoresist layer) is applied to the surface of a semiconductor substrate, and the photosensitive layer is exposed using a pattern of high-brightness light to create an image of the feature-defining components of a semiconductor device on the photosensitive layer. As semiconductor processes evolve to provide smaller critical dimensions, and devices become smaller and more complex (including the number of layers), there is a need for precise feature patterning methods to improve device quality, reliability, and yield.

[0004] Although many methods have been proposed to improve the execution of lithography processes, they are not entirely satisfactory in all aspects. Therefore, it is desirable to provide a solution to improve lithography systems in order to increase the production yield of semiconductor wafers. Summary of the Invention

[0005] Some embodiments of this disclosure provide a method for operating an electrostatic clamp, comprising: applying a voltage to an electrode layer of an electrostatic clamp, the electrode layer including a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the first electrode, the second electrode, the third electrode, and the fourth electrode are in a first polarization state; switching the electrical properties of the second electrode and the third electrode to a second polarization state opposite to the first polarization state; and switching the electrical properties of the first electrode and the fourth electrode to a second polarization state opposite to the first polarization state.

[0006] Other embodiments of this disclosure provide a method of operating an electrostatic clamp, comprising: applying a voltage to an electrode layer of the electrostatic clamp and providing a first adsorption force; performing a first depolarization process to depolarize a portion of the electrodes of the electrode layer and give the electrostatic clamp a second adsorption force distributed in a ring; performing a first repolarization process to repolarize this portion of the electrodes of the electrode layer and give it an electrical property opposite to that before the first depolarization process; performing a second depolarization process to depolarize another portion of the electrodes of the electrode layer and give the electrostatic clamp a third adsorption force distributed in a ring; and performing a second repolarization process to repolarize the other portion of the electrodes of the electrostatic clamp and give it an electrical property opposite to that before the second depolarization process.

[0007] Further embodiments of this disclosure provide an electrostatic clamp comprising: an electrode layer and a power control module. The electrode layer includes: a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the first electrode, second electrode, third electrode, and fourth electrode are electrically isolated from each other. The power control module is electrically connected to the electrode layer and configured to simultaneously switch the electrical properties of the second and third electrodes, and simultaneously switch the electrical properties of the first and fourth electrodes. Attached Figure Description

[0008] As described in the following detailed description, and in conjunction with the attached Figure 1 Reading this document will provide the best understanding of its contents. It is important to emphasize that, in accordance with industry standard practice, the features are not drawn to scale and are for illustrative purposes only. In fact, the dimensions of the features may be increased or decreased arbitrarily for clarity of discussion.

[0009] Figure 1 A schematic diagram illustrating a semiconductor substrate processing system according to some embodiments;

[0010] Figure 2 A top view schematic diagram of an electrostatic clamp according to some embodiments is shown;

[0011] Figure 3A and Figure 3B A top view of an electrostatic clamp according to some embodiments is shown;

[0012] Figure 4 A flowchart illustrating an electrostatic clamp operation method according to some implementation methods is provided;

[0013] Figures 5A to 5E The diagram illustrates the various stages in the process of the electrodes of the electrostatic clamp switching from the first polarization state to the second polarization state.

[0014] Figures 6A to 6E The diagram illustrates the various stages in the process of the electrodes of the electrostatic clamp switching from the second polarization state to the first polarization state.

[0015] Figures 7A to 7E The diagram illustrates the various stages in the process of the electrode voltage of the electrostatic clamp switching from the first polarization state to the second polarization state.

[0016] Figures 8A to 8E The diagram illustrates the various stages in the process of the electrodes of the electrostatic clamp switching from the first polarization state to the second polarization state.

[0017] Figure 9A A schematic diagram illustrating the force exerted by the electrostatic clamp on the photomask during a depolarization process;

[0018] Figure 9B A schematic diagram illustrating the force exerted by the electrostatic clamp on the photomask during a depolarization process;

[0019] Figure 10A and Figure 10B A top view of an electrostatic clamp according to some alternative embodiments is shown;

[0020] Figure 11A and Figure 11B A top view of an electrostatic clamp according to some alternative embodiments is shown;

[0021] Figures 12A to 12C A top view of an electrostatic clamp according to some alternative embodiments is shown;

[0022] Figure 13A and Figure 13B A top view of an electrostatic clamp according to some alternative embodiments is shown.

[0023] [Symbol Explanation]

[0024] 10: Semiconductor substrate processing system

[0025] 11: Carrier

[0026] 12: Loading Port

[0027] 100: Static Electricity Clamp

[0028] 110: Dielectric material

[0029] 110C: Central Region

[0030] 120: Clamping Electrode

[0031] 122: First electrode

[0032] 124: Second electrode

[0033] 126: Third electrode

[0034] 128: Fourth Electrode

[0035] 130: Power Control Module

[0036] 20: Transmission Module

[0037] 21: Control Circuit

[0038] 22: Robotic Arm

[0039] 200: Method

[0040] 210: Steps

[0041] 220: Steps

[0042] 230: Steps

[0043] 240: Steps

[0044] 250: Steps

[0045] 30: Switching Modules

[0046] 31: Robotic Arm

[0047] 32: Photomask Box

[0048] 300: Static Cleaner

[0049] 322: First electrode

[0050] 324: Second electrode

[0051] 326: Third electrode

[0052] 328: Fourth electrode

[0053] 40: Processing Module

[0054] 41: Radiation source

[0055] 42: Lighting Module

[0056] 43: Light Mask Stage

[0057] 44: Projection Optical Module

[0058] 45:Substrate table

[0059] 46: Gas Supply Module

[0060] 400: Static Clip

[0061] 422: First electrode

[0062] 424: Second electrode

[0063] 426: Third electrode

[0064] 428: Fourth electrode

[0065] 50: Control Module

[0066] 500: Static Clip

[0067] 522: First electrode

[0068] 524: Second electrode

[0069] 526: Third electrode

[0070] 528: Fourth Electrode

[0071] 600: Static Clip

[0072] 602: Electrode region

[0073] 622: First electrode

[0074] 624: Second electrode

[0075] 626: Third electrode

[0076] 628: Fourth Electrode

[0077] D1: First dimension

[0078] D2: Second size

[0079] D3: Third size

[0080] D4: Fourth Size

[0081] M: Light Mask

[0082] P1: Location

[0083] P2: Location

[0084] R: Extreme ultraviolet radiation

[0085] S1: Patterned surface

[0086] S2: Clamping surface

[0087] W: Semiconductor substrate Detailed Implementation

[0088] It is understood that the following disclosure provides many different implementations or embodiments for achieving the various features of this disclosure. Specific implementations or embodiments of components and configurations are described below to simplify this disclosure. Of course, these are merely embodiments and are not intended to be limiting. For example, the dimensions of elements are not limited to the disclosed range or values, but may depend on the process conditions of the device and / or the desired characteristics. Furthermore, in the following description, forming a first feature above or on a second feature may include implementations where the first and second features are formed in direct contact, and may also include implementations where additional features may be formed between the first and second features, so that the first and second features are not in direct contact. For simplicity and clarity, the various features may be drawn arbitrarily at different scales.

[0089] Furthermore, to facilitate the description of the relationship between one element or feature and another, as illustrated in the accompanying drawings, spatially relative terms such as "below," "below," "lower than," "above," "above," and similar terms may be used herein. In addition to the directions illustrated in the accompanying drawings, the spatially relative terms are intended to cover different orientations of the device in use or operation. The device may have other orientations (rotation 90 degrees or other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly. Furthermore, the term "made of" may mean either "comprising" or "consisting of."

[0090] Semiconductor wafers are fabricated in a series of sequential lithography steps, including mask alignment, exposure, photoresist development, layer etching, and layer deposition, to form patterns that define device structures and interconnections within integrated circuits. To ensure robust mask alignment, dedicated alignment structures are placed within the physical layout data of the integrated circuits, and on-line alignment tools in the semiconductor manufacturing process are used to achieve overlay (OVL) control during mask alignment. The patterned wafer consists of multiple integrated circuits arranged in a periodic array or master mask regions, each master mask region being patterned by a step-repeat tool configured to align the patterned mask with the individual master mask regions based on a wafer map of alignment structure positions obtained from the physical layout data of the integrated circuits. Yield and device performance depend on robust overlay control between two or more mask alignment steps when forming device layers.

[0091] As lithography processes become more complex, it is necessary to improve the overlay quality during mask alignment.

[0092] Figure 1A schematic diagram of a semiconductor substrate processing system according to some embodiments is shown. The semiconductor substrate processing system 10 includes a loading port 12, a transfer module 20, a switching module 30, and a processing module 40. In other embodiments, multiple components of the semiconductor substrate processing system 10 may be added or omitted.

[0093] In some embodiments, the loading port 12 is configured to load the photomask M from the carrier 11 into the semiconductor substrate processing system 10, or to remove the photomask M from the semiconductor substrate processing system 10 onto the carrier 11. In some embodiments, the loading port 12 is capable of accommodating two carriers 11. One of the two carriers 11 is used to load the photomask M to be transferred to the semiconductor substrate processing system 10, and the other is used to load the photomask M removed from the semiconductor substrate processing system 10.

[0094] The transfer module 20 is configured to transport the photomask M between the loading port 12 and the switching module 30. In some embodiments, the transfer module 20 is located between the loading port 12 and the switching module 30. The transfer module 20 may include control circuitry 21 and a robotic arm 22. The robotic arm 22 is controlled by electronic signals from the control circuitry 21. In some embodiments, the robotic arm 22 includes multi-axis mechanical manipulators and is configured to transport the photomask M. In some embodiments, the semiconductor substrate processing system 10 also includes a control module 50 configured to control the operation of multiple modules of the semiconductor substrate processing system 10.

[0095] The switching module 30 is configured to grasp the photomask M before moving it to the photomask stage 43 of the processing module 40 and after removing it from the photomask stage 43. In some embodiments, the switching module 30 includes a robotic arm 31 configured to transport the photomask M between the robotic arm 22 of the transfer module 20 and the photomask stage 43. During the transfer, the photomask M is received on or within the photomask cassette 32 grasped by the robotic arm 31.

[0096] In some embodiments, processing module 40 is a lithography system operable to perform a lithography exposure process using a suitable radiation source and exposure mode. In some embodiments, processing module 40 is an extreme ultraviolet (EUV) lithography system designed to expose a resist layer via EUV light. The resist layer is a suitable material sensitive to EUV light. The EUV lithography system employs a radiation source 41 to generate EUV light, for example, EUV light with a wavelength between about 1 nanometer and 100 nanometers. In one specific embodiment, radiation source 41 generates EUV light with a wavelength of approximately 13.5 nanometers. In some embodiments, radiation source 41 utilizes the mechanism of laser-produced plasma (LPP) to generate EUV radiation R. In some embodiments, processing module 40 further includes a gas supply module 46 designed to supply hydrogen to radiation source 41, which helps reduce contamination in radiation source 41.

[0097] In some embodiments, the processing module 40 also utilizes an illumination module 42. In various embodiments, the illumination module 42 includes various reflective optics, such as a single mirror or a mirror system with multiple mirrors, to guide light from the radiation source 41 onto the photomask stage 43 of the processing module 40, particularly the photomask M fixed to the photomask stage 43.

[0098] The photomask stage 43 is configured to hold the photomask M. In some embodiments, the photomask stage 43 includes an electrostatic clamp for holding the photomask M. For example... Figure 1 As shown, the reflective photomask M is held by the photomask stage 43 such that the patterned surface S1 of the photomask M faces downward, and the clamping surface S2 opposite to the patterned surface S1 faces the photomask stage 43.

[0099] The processing module 40 also includes a projection optics module 44 for imaging the pattern of the photomask M onto a semiconductor substrate W fixed on a substrate stage 45 of the processing module 40. The projection optics module 44 has optics for projecting reflected extreme ultraviolet (EUV) light. The projection optics module 44 collects the EUV light emitted from the photomask M, which carries an image of the pattern defined on the photomask M. In some embodiments, the semiconductor substrate W is coated with an EUV-sensitive resist layer.

[0100] In some embodiments, when the robotic arm 31 of the switching module 30 moves the photomask M into the processing module 40, the photomask stage 43 first moves to position P1 (also referred to as the device position) via a driver (not shown), as in Figure 1As shown in the diagram. At position P1, the photomask stage 43 is positioned above the photomask M on the robotic arm 31. Then, via electrostatic attraction, the photomask M is clamped onto the photomask stage 43 and moved to position P2 (also known as the processing position). Position P2 is positioned above the semiconductor substrate W for subsequent lithography processes. After the lithography process, the photomask stage 43 is moved to the unloading position (similar to...). Figure 1 The device is positioned at location P1. In the unloading position, the electrostatic attraction is released, and the photomask M is removed from the photomask stage 43. The robotic arm receives the photomask M and sends it out of the processing module 40 for subsequent processing or storage.

[0101] The electrode layer of the electrostatic fixture in the photomask stage 43 has several electrodes that generate electrostatic attraction by supplying a positive and / or negative voltage from a voltage source. As charge accumulates on the electrostatic fixture during continuous workpiece processing, the polarity of these electrodes must be switched periodically to avoid continuous polarization. This helps to prevent polarization of the dielectric material of the electrostatic fixture and makes it difficult to remove the photomask from the photomask stage.

[0102] During the switching of electrode electrical properties, the photomask remains held on the photomask stage. Therefore, the switching of electrode electrical properties can be performed by switching the electrical properties of some electrodes at a time, while the other electrodes retain their original electrical properties, so that the electrostatic clamp still has sufficient attraction to hold the substrate. Therefore, the voltage supply to some of the electrodes must be cut off, and then a voltage of the opposite electrical property must be supplied. Then the voltage supply to the remaining electrodes must be cut off, and then another voltage of the opposite electrical property must be supplied.

[0103] Some embodiments of this disclosure provide an electrostatic clamp with an improved configuration of the electrode pattern for providing a ring-shaped force when holding a component (e.g., a photomask or wafer), such that the force generated when the electrodes change from a depolarized to a polarized state when the electrical properties of the electrostatic clamp are switched does not cause warping of the component (e.g., a photomask or wafer).

[0104] Figure 2 This is a top view of an electrostatic clamp on a photomask stage according to some embodiments of the present disclosure. The electrostatic clamp 100 includes a dielectric body 110 and an electrode layer embedded in the dielectric body 110, wherein the electrode layer includes a plurality of clamping electrodes 120. In some embodiments, the electrostatic clamp 100 includes four clamping electrodes 120. The number of clamping electrodes may vary in different embodiments.

[0105] The clamping electrode 120 provides electrostatic attraction while receiving voltage to secure the photomask M to the clamping surface. In some embodiments, the clamping electrode 120 is located in the central region 110C of the dielectric body 110, wherein the central region 110C has an area substantially equal to the area of ​​the photomask M, so that the photomask M can be stably fixed on the electrostatic clamp.

[0106] In some embodiments, the clamping electrode 120 of the electrostatic clamp 100 includes a first electrode 122, a second electrode 124 surrounding the first electrode 122, a third electrode 126 surrounding the second electrode 124, and a fourth electrode 128 surrounding the third electrode 126. The first electrode 122, the second electrode 124, the third electrode 126, and the fourth electrode 128 are electrically isolated from each other via a dielectric material or an insulating material.

[0107] In some embodiments, the sum of the areas of the first electrode 122 and the second electrode 124 is equal to the sum of the areas of the third electrode 126 and the fourth electrode 128. In other embodiments, the areas of the first electrode 122, the second electrode 124, the third electrode 126, and the fourth electrode 128 may be the same.

[0108] In some implementations, such as in Figure 2 As shown, the first electrode has one side length with a first dimension D1, the second electrode 124 has one side dimension D2, the third electrode 126 has one side dimension D3, and the fourth electrode 128 has one side dimension D4, wherein the first dimension D1 is greater than the second dimension D2, the second dimension D2 is greater than the third dimension D3, and the third dimension D3 is greater than the fourth dimension D4. In other words, the dimensions of the sides of the plurality of annular electrodes surrounding the first electrode 122 decrease from the inside out.

[0109] As in Figure 2 As shown, the electrostatic clamp 100 further includes a power control module 130, which electrically connects the first electrode 122, the second electrode 124, the third electrode 126, and the fourth electrode 128 to provide different electrical voltages to each electrode to generate electrostatic force. In some embodiments, the voltage provided by the power control module 130 may be a direct current between approximately 0.5 and 3 kV, for example, approximately 1 kV, i.e., approximately +1 kV and -1 kV. Other voltage values ​​may also be used in other embodiments. The power control module 130 also controls the switching of the electrical properties of the first electrode 122, the second electrode 124, the third electrode 126, and the fourth electrode 128.

[0110] In the process of switching the electrical properties of an electrode, the voltage supplied to the electrode is first cut off, and then a voltage with the opposite electrical properties is supplied to the electrode, for example, to switch the electrode from being positively charged to being negatively charged, or from being negatively charged to being positively charged.

[0111] In some embodiments, the power control module 130 controls the second electrode 124 and the third electrode 126 to switch electrical properties simultaneously, and controls the first electrode 122 and the fourth electrode 128 to switch electrical properties simultaneously.

[0112] In this paper, the electrode in the first polarization state can be either positively or negatively charged, while in the second polarization state, the electrode has the opposite charge to that in the first polarization state.

[0113] Figure 3A and Figure 3B This is a top view of an electrostatic clamp 100 according to some embodiments. (As shown in...) Figure 3A As shown, the clamping electrodes 120 of the electrostatic clamp 100 are in a first polarization state, wherein the first electrode 122 and the second electrode 124 are positively charged, and the third electrode 126 and the fourth electrode 128 are negatively charged. For example, in... Figure 3B As shown, the clamping electrodes 120 of the electrostatic chuck are in a second polarization state, wherein the first electrode 122 and the second electrode 124 are negatively charged, and the third electrode 126 and the fourth electrode 128 are positively charged. The electrical properties of the clamping electrodes 120 of the electrostatic chuck 100 can be switched during non-exposed wafer processing after continuously exposing several wafers. For example, after exposing several wafers, the clamping electrodes 120 of the electrostatic chuck 100 are switched from the first polarization state to the second polarization state, and then after exposing several more wafers, the clamping electrodes 120 of the electrostatic chuck 100 are switched from the second polarization state to the first polarization state.

[0114] In other words, in the first polarization state, for example, the first electrode 122 and the second electrode 124 have the same first electrical charge (e.g., positive), and the third electrode 126 and the fourth electrode 128 have the same second electrical charge (e.g., negative), with the first and second electrical charges being opposite in nature. Then, in the second polarization state, for example, the first electrode 122 and the second electrode 124 have the same second electrical charge (e.g., negative), and the third electrode 126 and the fourth electrode 128 have the same first electrical charge (e.g., positive).

[0115] Figure 4 A flowchart illustrating an operation method of an electrostatic clamp according to some embodiments is shown. In method 200, step 210 involves applying a voltage to bring the first, second, third, and fourth electrodes into a first polarization state. See also... Figure 5AEach clamping electrode 120 of the electrostatic clamp 100 is in a first polarization state, wherein the first electrode 122 and the second electrode 124 are positively charged, and the third electrode 126 and the fourth electrode 128 are negatively charged.

[0116] In step 220 of method 200, the electrical properties of the second and third electrodes are switched to a second polarization state, which is opposite to the first polarization state. See also Figure 5B and Figure 5C The switching of the electrode's electrical properties involves stopping the voltage supply and then supplying a voltage with the opposite electrical properties to the first polarization state. For example, in... Figure 5B As shown, the second electrode 124 and the third electrode 126 are in a depolarized state at this time. During this depolarization period, the first electrode 122 and the fourth electrode 128 still maintain their electrical properties, with the first electrode 122 being positively charged and the fourth electrode 128 being negatively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the component. Figure 5C As shown, the second electrode 124 is repolarized to become negatively charged, and the third electrode 126 is repolarized to become positively charged.

[0117] In step 230 of method 200, the electrical properties of the first electrode and the fourth electrode are switched to a second polarization state, which is opposite to the first polarization state. For example, in... Figure 5D and Figure 5E As shown, switching the electrical properties of the electrodes involves stopping the supply voltage and then supplying a voltage with the opposite electrical properties to the first polarization state. (As in...) Figure 5D As shown, the first electrode 122 and the fourth electrode 128 are in a depolarized state at this time. During this depolarization period, the second electrode 124 and the third electrode 126 still maintain their electrical properties, with the second electrode 124 being negatively charged and the third electrode 126 being positively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the components. Figure 5E As shown, the first electrode 122 is repolarized to become negatively charged, and the fourth electrode 128 is repolarized to become positively charged.

[0118] By switching the electrical properties of the electrodes twice, the first electrode 122, the second electrode 124, the third electrode 126, and the fourth electrode 128 have changed from the first polarization state to the second polarization state.

[0119] Then, the clamping electrode 120 changes from the second polarization state to the first polarization state in a similar manner. In step 240 of method 200, the electrical properties of the second and third electrodes are switched to the first polarization state, see [link to previous section]. Figures 6A to 6C .exist Figure 6A In this state, the clamping electrodes 120 of the electrostatic clamp 100 are in a second polarization state, with the first electrode 122 and the second electrode 124 being negatively charged, and the third electrode 126 and the fourth electrode 128 being positively charged. For example, in... Figure 6B and Figure 6CAs shown, the switching of the electrode's electrical properties involves stopping the supply voltage and then supplying a voltage with the opposite electrical properties to the second polarization state. Figure 6B During this process, the second electrode 124 and the third electrode 126 are in a depolarized state. During this depolarization period, the first electrode 122 and the fourth electrode 128 maintain their electrical properties, with the first electrode 122 being negatively charged and the fourth electrode 128 being positively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the component. Figure 6C In the process, the second electrode 124 is repolarized and becomes positively charged, while the third electrode 126 is repolarized and becomes negatively charged.

[0120] In step 250 of method 200, the electrical properties of the first electrode and the fourth electrode are switched to a first polarization state. For example, in... Figure 6D and Figure 6E As shown, switching the electrical properties of the electrodes involves stopping the supply voltage and then supplying a voltage with the opposite electrical properties to the second polarization state. Figure 6D In this state, the first electrode 122 and the fourth electrode 128 are depolarized. During this depolarization period, the second electrode 124 and the third electrode 126 maintain their electrical properties, with the second electrode 124 being positively charged and the third electrode 126 being negatively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the component. Figure 6E In the process, the first electrode 122 is repolarized to become positively charged, and the fourth electrode 128 is repolarized to become negatively charged.

[0121] By switching the electrical properties of the electrodes twice, the first electrode 122, the second electrode 124, the third electrode 126, and the fourth electrode 128 have changed from the second polarization state to the first polarization state.

[0122] Figures 7A to 7E According to some other embodiments, this is a method for switching the polarization state of the electrodes of the electrostatic clamp 100. Figures 7A to 7E and Figures 5A to 5E The difference lies in that the electrical properties of the innermost and outermost electrodes (i.e., the first and fourth electrodes) are switched first, and then the electrical properties of the two middle electrodes (i.e., the second and third electrodes) are switched. In other words, in... Figure 4 In method 200, the order of steps 220 and 230 is interchangeable.

[0123] See Figure 7A Each clamping electrode 120 of the electrostatic clamp 100 is in a first polarization state, wherein the first electrode 122 and the second electrode 124 are negatively charged, and the third electrode 126 and the fourth electrode 128 are positively charged.

[0124] Figures 7B to 7CThe process shown corresponds to step 230 of method 200, switching the electrical properties of the first and fourth electrodes to a second polarization state opposite to the first polarization state. For example, in... Figure 7B and Figure 7C As shown, switching the electrical properties of the electrodes involves stopping the supply voltage and then supplying a voltage with the opposite electrical properties to the first polarization state. (As in...) Figure 7B As shown, the first electrode 122 and the fourth electrode 128 are in a depolarized state at this time. During this depolarization period, the second electrode 124 and the third electrode 126 still maintain their electrical properties, with the second electrode 124 being negatively charged and the third electrode 126 being positively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the components. Figure 7C As shown, the first electrode 122 is repolarized to become positively charged, and the fourth electrode 128 is repolarized to become negatively charged.

[0125] Figures 7D to 7E The process shown corresponds to step 220 of method 200, switching the electrical properties of the second and third electrodes to a second polarization state opposite to the first polarization state. For example, in... Figure 7D and Figure 7E As shown, switching the electrical properties of the electrodes involves stopping the supply voltage and then supplying a voltage with the opposite electrical properties to the first polarization state. (As in...) Figure 7D As shown, the second electrode 124 and the third electrode 126 are in a depolarized state at this time. During this depolarization period, the first electrode 122 and the fourth electrode 128 still maintain their electrical properties, with the first electrode 122 being positively charged and the fourth electrode 128 being negatively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the component. Figure 7E As shown, the second electrode 124 is repolarized to become positively charged, and the third electrode 126 is repolarized to become negatively charged.

[0126] Figures 8A to 8E According to some other embodiments, this is a method for switching each electrode of the electrostatic clamp 100 from a dual polarization state to a first polarization state. Figures 8A to 8E and Figures 6A to 6E The difference lies in that the electrical properties of the inner and outer electrodes (i.e., the first electrode 122 and the fourth electrode 128) are switched first, and then the electrical properties of the two middle electrodes (i.e., the second electrode 124 and the third electrode 126) are switched. In other words, in... Figure 4 In method 200, the order of steps 240 and 250 is interchangeable.

[0127] See Figure 8A Each clamping electrode 120 of the electrostatic clamp 100 is in a second polarization state, wherein the first electrode 122 and the second electrode 124 are positively charged, and the third electrode 126 and the fourth electrode 128 are negatively charged.

[0128] Figures 8B to 8CThe process shown is equivalent to step 250 of method 200, switching the electrical properties of the first and fourth electrodes to a first polarization state. For example, in... Figure 8B and Figure 8C As shown, the switching electrode's electrical properties include stopping the supply voltage and then supplying a voltage opposite to the second polarization state. (As in...) Figure 8B As shown, the first electrode 122 and the fourth electrode 128 are in a depolarized state at this time. During this depolarization period, the second electrode 124 and the third electrode 126 still maintain their electrical properties, with the second electrode 124 being positively charged and the third electrode 126 being negatively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the component. Figure 8C As shown, the first electrode 122 is repolarized to become negatively charged, and the fourth electrode 128 is repolarized to become positively charged.

[0129] Figures 8D to 8E The process shown corresponds to step 240 of method 200, switching the electrical properties of the second and third electrodes to the first polarization state. For example, in... Figure 8D and Figure 8E As shown, switching the electrical properties of the electrodes involves stopping the supply voltage and then supplying a voltage with the opposite electrical properties to the second polarization state. (As in...) Figure 8D As shown, the second electrode 124 and the third electrode 126 are in a depolarized state at this time. During this depolarization period, the first electrode 122 and the fourth electrode 128 still maintain their electrical properties, with the first electrode 122 being negatively charged and the fourth electrode 128 being positively charged. Therefore, the electrostatic clamp 100 can maintain the adsorption and holding of the component. Figure 8E As shown, the second electrode 124 is repolarized to become negatively charged, and the third electrode 126 is repolarized to become positively charged.

[0130] Figure 9A The diagram illustrates the distribution of forces acting on the electrostatic clamp 100 when the second electrode 124 and the third electrode 126 are depolarized. It shows that there are adsorption forces distributed at the innermost and outermost edges of the electrode region of the electrostatic clamp 100. Because the adsorption forces are distributed in a ring shape at the center and periphery, the electrostatic clamp 100 can hold the photomask flat without warping. Furthermore, when the second electrode 124 and the third electrode are repolarized, the electrostatic clamp 100 can maintain a flat hold on the photomask M without warping due to the ring-shaped force distribution.

[0131] Figure 9BThe diagram illustrates the distribution of the forces acting on the electrostatic clamp 100 when the first electrode 122 and the fourth electrode 128 are depolarized. It shows an adsorption force distribution within the electrode regions of the electrostatic clamp 100. Since the adsorption force is distributed in a ring shape within the regions of the second electrode 124 and the third electrode 126, the electrostatic clamp 100 can hold the photomask flat without warping. Furthermore, when the first electrode 122 and the fourth electrode are repolarized, the forces are distributed in a ring shape at the center and periphery of the electrode regions, allowing the electrostatic clamp 100 to maintain a flat hold on the photomask M without warping.

[0132] The electrostatic clamp provided in some embodiments of this disclosure exhibits a ring-shaped adsorption force (first adsorption force) on all electrodes of the clamp when voltage is applied, due to the electrode pattern arrangement. During the first depolarization process, some electrodes depolarize while others remain charged. At this time, although only a small number of electrodes provide adsorption force, the adsorption force (second adsorption force) is still ring-shaped. Subsequently, during the second depolarization process, another portion of the electrodes depolarizes while the previously mentioned portion remains charged, and the adsorption force (third adsorption force) is still ring-shaped. Therefore, the electrostatic clamp of this disclosure can reduce warping of the clamping element during the switching of electrical properties of the electrostatic clamp.

[0133] Figure 10A and Figure 10B This is a top view of an alternative embodiment of the electrostatic clamp. The electrostatic clamp 300 has four electrode regions, wherein the first electrode 322 is a single electrode, the second electrode 324 includes multiple triangular sub-electrodes, the third electrode 326 includes multiple triangular sub-electrodes, and the fourth electrode 328 includes multiple triangular sub-electrodes. In the electrostatic clamp 300, each sub-electrode is electrically insulated from each other and independently electrically connected to the power control module. Figure 10A In the electrostatic clamp 300, each electrode is in a first polarization state, wherein all sub-electrodes of the first electrode 322 and the second electrode 324 are positively charged, and all sub-electrodes of the third electrode 326 and the fourth electrode 328 are negatively charged. Figure 10B In the electrostatic clamp 300, each electrode is in the second polarization state, wherein all sub-electrodes of the first electrode 322 and the second electrode 324 are negatively charged, and all sub-electrodes of the third electrode 326 and the fourth electrode 328 are positively charged.

[0134] The procedure for switching the electrostatic clamp 300 can be referred to, for example, the aforementioned Figures 5A to 5E , Figures 6A to 6E , Figures 7A to 7E , Figures 8A to 8EThe content under discussion. In some embodiments, since the total area of ​​the first electrode 322 and the second electrode 324 is smaller than the total area of ​​the third electrode 326 and the fourth electrode 328, the electrostatic clamp 300 can have a suitable adsorption force by adjusting the value of the supplied voltage. For example, the first electrode 322 and the second electrode 324 can be supplied with a larger value of supply voltage, while the third electrode 326 and the fourth electrode 328 can be supplied with a smaller value of supply voltage.

[0135] In some embodiments, since the electrodes of the electrostatic clamp 300 are divided into multiple sub-electrodes, the charging time required when a voltage is applied to the electrodes can be reduced, allowing the electrodes to polarize more quickly.

[0136] Figure 11A and Figure 11B This is a top view of an alternative embodiment of the electrostatic clamp. The electrostatic clamp 400 has four electrode regions, wherein the first electrode 422 is a single electrode, the second electrode 424 includes four rectangular sub-electrodes, the third electrode 426 includes four rectangular sub-electrodes, and the fourth electrode 428 includes four rectangular sub-electrodes. In the electrostatic clamp 400, each sub-electrode is electrically insulated from each other and independently electrically connected to the power control module. Figure 11A In the electrostatic clamp 400, each electrode is in a first polarization state, wherein all sub-electrodes of the first electrode 422 and the second electrode 424 are positively charged, and all sub-electrodes of the third electrode 426 and the fourth electrode 428 are negatively charged. Figure 11B In the electrostatic clamp 400, each electrode is in the second polarization state, wherein all sub-electrodes of the first electrode 422 and the second electrode 424 are negatively charged, and all sub-electrodes of the third electrode 426 and the fourth electrode 428 are positively charged.

[0137] The procedure for switching the electrostatic clamp 400 can be referred to, for example, the aforementioned Figures 5A to 5E , Figures 6A to 6E , Figures 7A to 7E , Figures 8A to 8E The content under discussion. In some embodiments, since the electrostatic clamp 400 divides the electrode into multiple sub-electrodes, the charging time required when applying voltage to the electrode can be reduced, allowing the electrode to polarize more quickly.

[0138] Figures 12A to 12C A top view of an electrostatic clamp 500 according to an alternative implementation is shown. Figure 12AThe electrostatic clamp 500 includes a first electrode 522 (containing four sub-electrodes) located in a central region, a second electrode 524 surrounding the first electrode 522, a third electrode 526 surrounding the second electrode 524, and a fourth electrode 528 surrounding the third electrode 526, wherein each of the first electrode 522, second electrode 524, third electrode 526, and fourth electrode 528 comprises multiple sub-electrodes. In the electrostatic clamp 500, each sub-electrode is electrically insulated from each other and independently electrically connected to a power control module. Figure 12B The electrical properties of each sub-electrode of the electrostatic clamp are shown in the first polarization state, with positively charged and negatively charged sub-electrodes distributed alternately. Figure 12C This shows the electrical properties of each sub-electrode of the electrostatic clamp in the second polarization state. The electrical properties of each sub-electrode are reversed, and the positively charged sub-electrodes and the negatively charged sub-electrodes are distributed alternately.

[0139] Figure 13A and Figure 13B The image shows a top view of an electrostatic clamp according to an alternative embodiment. The electrostatic clamp 600 includes four electrically isolated electrode regions 602, each electrode region 602 including a first electrode 622, a second electrode 624, a third electrode 626, and a fourth electrode 628. Figure 13A In the electrostatic clamp 600, each electrode is in a first polarization state, wherein the first electrode 622 and the second electrode 624 in each electrode region 602 are positively charged, and the third electrode 626 and the fourth electrode 628 are negatively charged. Figure 13B In the electrostatic clamp 600, each electrode is in a second polarization state, wherein the first electrode 622 and the second electrode 624 in each electrode region 602 are negatively charged, and the third electrode 626 and the fourth electrode 628 are positively charged.

[0140] The procedure for switching the electrostatic clamp 600 can be found in the aforementioned example. Figures 5A to 5E , Figures 6A to 6E , Figures 7A to 7E , Figures 8A to 8E The content under discussion. In some embodiments, since the electrostatic clamp 600 is divided into multiple electrode regions 602, the area of ​​the electrodes in each region is smaller, thus reducing the charging time required when a voltage is applied to the electrodes, allowing the electrodes to polarize more quickly.

[0141] The electrostatic clamp disclosed herein can be used to clamp photomasks and wafers. Because the adsorption force of the electrostatic clamp is distributed in a ring shape, it can maintain the flatness of the clamped parts (e.g., photomasks or wafers) and reduce warpage when clamping photomasks or wafers, thus helping to improve the stacking control in lithography processes.

[0142] Some embodiments of this disclosure provide a method for operating an electrostatic clamp, comprising: applying a voltage to an electrode layer of the electrostatic clamp, the electrode layer including a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the first, second, third, and fourth electrodes are in a first polarization state; switching the electrical properties of the second and third electrodes to a second polarization state opposite to the first polarization state; and switching the electrical properties of the first and fourth electrodes to a second polarization state opposite to the first polarization state. In some embodiments, the method for operating the electrostatic clamp further comprises: switching the electrical properties of the second and third electrodes, causing the electrical properties of the second and third electrodes to change from a second polarization state to a first polarization state; and switching the electrical properties of the first and fourth electrodes, causing the electrical properties of the first and fourth electrodes to change from a second polarization state to a first polarization state. In some embodiments, wherein in the first polarization state, the first and second electrodes are of the first electrical property, and the third and fourth electrodes are of the second electrical property opposite to the first electrical property. In some embodiments, each of the first, second, third, and fourth electrodes comprises a plurality of sub-electrodes, and when a voltage is applied to the electrode layer of the electrostatic clamp, the electrical properties of the plurality of sub-electrodes are configured to alternate between a first electrical property and a second electrical property, wherein the electrical properties of the first electrical property are opposite to those of the second electrical property. In some embodiments, switching the electrical properties of the second and third electrodes and switching the electrical properties of the first and fourth electrodes each include a depolarization process and a repolarization process.

[0143] Other embodiments of this disclosure provide a method of operating an electrostatic clamp, comprising: applying a voltage to an electrode layer of the electrostatic clamp and providing a first adsorption force; performing a first depolarization process, depolarizing a portion of the electrodes of the electrode layer and giving the electrostatic clamp a second adsorption force distributed in a ring; performing a first repolarization process, repolarizing this portion of the electrodes of the electrode layer and giving it an electrical property opposite to that before the first depolarization process; performing a second depolarization process, depolarizing another portion of the electrodes of the electrode layer and giving the electrostatic clamp a third adsorption force distributed in a ring; and performing a second repolarization process, repolarizing the other portion of the electrodes of the electrostatic clamp and giving it an electrical property opposite to that before the second depolarization process. In some embodiments, the electrode layer includes a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the portion of the electrodes is the second and third electrodes, and the other portion of the electrodes is the first and fourth electrodes. In some embodiments, during the period when voltage is applied to the electrode layer of the electrostatic clamp and a first adsorption force is provided, the first and second electrodes have the same electrical properties, and the third and fourth electrodes have the same electrical properties.

[0144] Other embodiments of this disclosure provide a method for operating an electrostatic clamp, comprising: applying a voltage to an electrode layer of the electrostatic clamp, wherein the electrode layer includes: a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the first electrode, second electrode, third electrode, and fourth electrode are in a first polarization state; performing a first depolarization process to depolarize the second electrode and the third electrode, followed by performing a first repolarization process to make the electrical properties of the second electrode and the third electrode opposite to the first polarization state; and performing a second depolarization process to depolarize the first electrode and the fourth electrode, followed by performing a second repolarization process to make the electrical properties of the first electrode and the fourth electrode opposite to the first polarization state. In some embodiments, wherein in the first polarization state, the first electrode and the second electrode are of the first electrical property, and the third electrode and the fourth electrode are of the second electrical property opposite to the first electrical property. In some embodiments, each of the first, second, third, and fourth electrodes comprises a plurality of sub-electrodes, and when a voltage is applied to the electrode layer of the electrostatic clamp, the electrical properties of the plurality of sub-electrodes are configured to alternate between a first electrical property and a second electrical property, wherein the electrical properties of the first electrical property are opposite to those of the second electrical property. In some embodiments, the first electrode is a single electrode, and the second, third, and fourth electrodes comprise a plurality of sub-electrodes. In some embodiments, the polarization of the plurality of sub-electrodes within an electrode is the same electrical property. In some embodiments, the polarization of the plurality of sub-electrodes within an electrode is an alternating arrangement of different electrical properties. In some embodiments, the method of operating the electrostatic clamp further comprises: performing a third depolarization process to depolarize the second and third electrodes, followed by a third repolarization process to make the electrical properties of the second and third electrodes opposite to the second polarization state; and performing a fourth depolarization process to depolarize the first and fourth electrodes, followed by a fourth repolarization process to make the electrical properties of the first and fourth electrodes opposite to the second polarization state.

[0145] Further embodiments of this disclosure provide an electrostatic clamp comprising: an electrode layer and a power control module. The electrode layer includes: a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the first, second, third, and fourth electrodes are electrically isolated from each other. The power control module is electrically connected to the electrode layer and configured to simultaneously switch the electrical characteristics of the second and third electrodes, and simultaneously switch the electrical characteristics of the first and fourth electrodes. In some embodiments, the power control module is configured to have the first and second electrodes as a first electrical characteristic, and to have the third and fourth electrodes as a second electrical characteristic opposite to the first electrical characteristic. In some embodiments, the sum of the areas of the first and second electrodes is equal to the sum of the areas of the third and fourth electrodes. In some embodiments, the first, second, third, or fourth electrode comprises a plurality of sub-electrodes electrically isolated from each other. In some embodiments, the plurality of electrodes are triangular or rectangular.

[0146] The foregoing has outlined features of several or more embodiments to enable those skilled in the art to better understand various aspects of this disclosure. Those skilled in the art will understand that they can readily use this disclosure as a basis for the design and modification of other processes and structures to achieve the same purpose or advantages as the embodiments or implementations described herein. Those skilled in the art will also understand that such equivalent constructions do not depart from the spirit and scope of this disclosure, and that various changes, substitutions, and modifications can be made without departing from the spirit and scope of this disclosure.

Claims

1. A method of operating an electrostatic clamp, characterized by, comprising: applying a voltage to an electrode layer of an electrostatic clamp, the electrode layer comprising a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the first electrode, the second electrode, the third electrode, the fourth electrode are in a first polarization state; switching the second electrode and the third electrode to a second polarization state opposite to the first polarization state; and switching the first electrode and the fourth electrode to the second polarization state opposite to the first polarization state.

2. The method of operating an electrostatic clamp of claim 1, wherein, further comprising: switching the second electrode and the third electrode from the second polarization state to the first polarization state; and switching the first electrode and the fourth electrode from the second polarization state to the first polarization state.

3. The method of operating an electrostatic clamp of claim 1, wherein, in the first polarization state, the first electrode and the second electrode are in a first electrical property, and the third electrode and the fourth electrode are in a second electrical property opposite to the first electrical property.

4. The method of operating an electrostatic clamp of claim 1, wherein, the first electrode, the second electrode, the third electrode, and the fourth electrode each comprise a plurality of sub-electrodes, and when the voltage is applied to the electrode layer of the electrostatic clamp, the electrical properties of the sub-electrodes are arranged in an alternating arrangement of the first electrical property and the second electrical property, wherein the electrical property of the first electrical property is opposite to the electrical property of the second electrical property.

5. A method of operating an electrostatic clamp, characterized by, comprising: applying a voltage to an electrode layer of an electrostatic clamp and providing a first attractive force; performing a first depolarization process to depolarize a portion of electrodes of the electrode layer and the electrostatic clamp has a second attractive force in a ring-like distribution; performing a first repolarization process to repolarize the portion of electrodes of the electrode layer and has an electrical property opposite to before the first depolarization process; performing a second depolarization process to depolarize another portion of electrodes of the electrode layer and the electrostatic clamp has a third attractive force in a ring-like distribution; and performing a second repolarization process to repolarize the other portion of electrodes of the electrostatic clamp and has an electrical property opposite to before the second depolarization process; wherein the electrode layer comprises a first electrode, a second electrode surrounding the first electrode, a third electrode surrounding the second electrode, and a fourth electrode surrounding the third electrode, wherein the portion of electrodes are the second electrode and the third electrode, and the other portion of electrodes are the first electrode and the fourth electrode.

6. The method of operating an electrostatic clamp of claim 5, wherein, the first electrode, the second electrode, the third electrode, and the fourth electrode have the same area.

7. The method of operating an electrostatic clamp of claim 5, wherein, during the applying a voltage to the electrode layer of the electrostatic clamp and providing the first attractive force, the first electrode and the second electrode have the same electrical property, and the third electrode and the fourth electrode have the same electrical property.

8. An electrostatic clamp, characterized by comprising: an electrode layer comprising: a first electrode; a second electrode surrounding the first electrode; a third electrode surrounding the second electrode; and a fourth electrode surrounding the third electrode, wherein the first electrode, the second electrode, the third electrode, and the fourth electrode are electrically isolated from each other; and a power control module electrically connected to the electrode layer, configured to switch the second electrode and the third electrode electrically at the same time, and switch the first electrode and the fourth electrode electrically at the same time.

9. The electrostatic clamp of claim 8, wherein, a sum of areas of the first electrode and the second electrode is equal to a sum of areas of the third electrode and the fourth electrode.

10. The electrostatic clamp of claim 8, wherein, the first electrode, the second electrode, the third electrode, or the fourth electrode comprises a plurality of sub-electrodes electrically isolated from each other.

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