Thickness measurement device, method and lithography equipment thereof

Abstract

The present disclosure relates to a thickness measuring device, a method and a lithography device thereof. The thickness measuring device according to the present disclosure may include: a body for supporting the thickness measuring device; a light emitting module for emitting measurement light; a light receiving module for receiving measurement light; and a guide column, the first end of which is placed in contact with the surface of the workpiece to be processed, wherein the light emitting module and the light receiving module are arranged relative to each other so that the light emitted by the light emitting module is received by the light receiving module at a predetermined receiving position of the light receiving module, and the predetermined receiving position depends on the initial receiving position and the thickness of the workpiece to be processed. The thickness measuring device according to the present disclosure determines the thickness of the workpiece to be processed based on the distance between the predetermined receiving position where the light receiving module receives the light and the initial receiving position. The thickness measuring device according to the present disclosure converts the thickness of the workpiece to be processed into the physical stroke of the guide column, so that it can be applied to measuring the thickness of various types of workpieces to be processed.

Description

Technical Field

[0001] The present application relates to the field of industrial measurement, and in particular to a thickness measurement device, method and lithography equipment thereof. Background Art

[0002] In the field of industrial manufacturing, accurate measurement of the thickness of the workpiece is extremely critical to ensure the quality of processing. Especially in the wafer manufacturing process of the semiconductor industry, accurate thickness measurement is crucial to the successful implementation of photolithography. Photolithography relies on optical projection methods to transfer fine patterns to the surface of photosensitive materials. The main steps involved include mask preparation, wafer coating with photoresist, alignment and exposure, and development. Before these steps, accurate measurement of the thickness of the wafer is crucial to ensure the accuracy of the exposure and development process. Traditional thickness measurement methods may have problems with insufficient accuracy or complex operation, which may lead to errors in subsequent processing steps and affect the quality of the final product.

[0003] Therefore, there is an urgent need for a measuring device that can accurately measure the thickness of the workpiece to be processed to provide reliable thickness data for subsequent processing. Summary of the invention

[0004] To overcome one or more of the disadvantages of the prior art, the present disclosure provides a thickness measurement device, method, and lithography apparatus.

[0005] In a first aspect, the present disclosure provides a thickness measuring device. The thickness measuring device may include: a body for supporting the thickness measuring device; a light emitting module for emitting measuring light; a light receiving module for receiving measuring light; and a guide post, a first end of which is placed in contact with a surface of a workpiece to be processed, wherein the light emitting module and the light receiving module are arranged relative to each other so that the light emitted by the light emitting module is received by the light receiving module at a predetermined receiving position of the light receiving module, and the predetermined receiving position depends on an initial receiving position and a thickness of the workpiece to be processed.

[0006] According to one embodiment of the present disclosure, optionally, the initial receiving position may be a position where the light emitted by the light emitting module is received by the light receiving module when the guide pillar directly presses against the upper surface of the workbench.

[0007] According to an embodiment of the present disclosure, optionally, the thickness measuring device may further include: a lever rotating along the rotation axis, wherein a first end of the lever is fixed to the light emitting module and a second end of the lever is fixed to the guide pillar.

[0008] According to an embodiment of the present disclosure, optionally, the thickness measuring device may further include: a telescopic module, wherein a first end of the telescopic module is fixed to a first end of the lever.

[0009] According to one embodiment of the present disclosure, optionally, the thickness measuring device may further include: an electromagnet located below the lever and between the rotating shaft and the first end of the lever, wherein the electromagnet is energized to attract the first end of the lever to move downward, and wherein when the electromagnet is de-energized, the telescopic module pushes the first end of the lever to move upward, thereby causing the second end of the lever to press against the upper surface of the workpiece to be processed.

[0010] According to one embodiment of the present disclosure, optionally, the telescopic module may be a spring.

[0011] According to one embodiment of the present disclosure, optionally, the distance between the predetermined receiving position and the initial receiving position can be measured by a laser displacement sensor, a grating ruler, or a capacitive pressure difference sensor.

[0012] According to one embodiment of the present disclosure, optionally, the thickness measuring device may further include: a rigid structure, wherein the rigid structure fixes the body so that the guide column stands on and contacts the workbench, and wherein the movement range of the guide column depends on the stroke of the telescopic module.

[0013] According to one embodiment of the present disclosure, optionally, the thickness measuring device may further include: a rigid structure, wherein the rigid structure fixes the body so that the guide column stands on and contacts the workbench, and wherein the movement range of the guide column depends on the stroke of the telescopic module.

[0014] The thickness measuring device according to the present disclosure determines the thickness of the workpiece to be processed based on the distance between the predetermined receiving position and the initial receiving position. The thickness measuring device according to the present disclosure converts the thickness of the workpiece to be processed into the physical stroke of the guide pin, so that it can be applied to measuring the thickness of various types of workpieces to be processed, especially to measuring the thickness of transparent workpieces to be processed.

[0015] In a second aspect, the present disclosure provides a lithographic apparatus comprising a thickness measurement device as described above.

[0016] The lithography apparatus according to the present disclosure adopts the thickness measuring device as described above. The thickness measuring device determines the thickness of the workpiece to be processed based on the distance between the predetermined receiving position and the initial receiving position. That is, the thickness measuring device converts the thickness of the workpiece to be processed into the physical stroke of the guide pillar, so that it can be applied to measuring the thickness of various types of workpieces to be processed, especially to measuring the thickness of transparent workpieces to be processed.

[0017] In a third aspect, the present disclosure provides a method for measuring the thickness of a workpiece to be processed by the thickness measuring device as described above. The method may include: moving the workpiece to be processed above the workbench; releasing the telescopic module so that the guide pillar presses against the upper surface of the workpiece to be processed under the action of the telescopic module; and emitting light by the light emitting module, wherein the light emitted by the light emitting module is received by the light receiving module at a predetermined receiving position of the light receiving module, and wherein the predetermined receiving position depends on the initial receiving position and the thickness of the workpiece to be processed.

[0018] According to one embodiment of the present disclosure, optionally, the method may further include: driving the telescopic module so that the guide column is pressed against the upper surface of the workbench under the action of the telescopic module; and emitting light from the light emitting module, wherein the position where the light emitted by the light emitting module is received by the light receiving module is the initial receiving position.

[0019] The method for measuring the thickness of a workpiece to be processed according to the present disclosure determines the thickness of the workpiece to be processed based on the distance between the predetermined receiving position and the initial receiving position. The method for measuring the thickness of a workpiece to be processed according to the present disclosure converts the thickness of the workpiece to be processed into the physical stroke of the guide pin, and is suitable for measuring the thickness of various types of workpieces to be processed, and is particularly suitable for measuring the thickness of transparent workpieces to be processed.

[0020] These and other features and advantages will become apparent by reading the following detailed description and by reference to the associated drawings.It is to be understood that the foregoing general description and the following detailed description are illustrative only and are not restrictive of the aspects of what is claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to understand in detail the manner in which the above features of the present disclosure are used, the above briefly summarized contents may be described in more detail with reference to various embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings only show certain typical aspects of the present disclosure and should not be considered to limit its scope, as the description may allow for other equally effective aspects.

[0022] Figure 1 An example of a thickness measuring device is explained.

[0023] Figure 2 A schematic diagram illustrating a thickness measurement device according to an embodiment of the present disclosure is illustrated.

[0024] Figure 3 A schematic diagram illustrating initialization of a thickness measurement device according to an embodiment of the present disclosure.

[0025] Figure 4 A flowchart of a method for measuring the thickness of a workpiece to be processed by a thickness measuring device according to an embodiment of the present disclosure is illustrated.

[0026] Figure 5 A schematic diagram for deriving the thickness of a workpiece to be processed according to an embodiment of the present disclosure is illustrated.

[0027] Figure 6 A schematic structural diagram of a lithography apparatus including a thickness measurement device according to an embodiment of the present disclosure is illustrated. DETAILED DESCRIPTION

[0028] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the described embodiments. However, it will be apparent to those skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other embodiments, well-known structures or processing steps are not described in detail to avoid unnecessarily obscuring the concepts of the present disclosure.

[0029] In the description of the embodiments of the present disclosure, it should be noted that, unless otherwise specified, the term "plurality" means more than two; the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone; the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present disclosure belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure; the terms "including" and "having" in the specification and claims of the present disclosure and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0031] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0032] As used herein, the terms "docking", "coupling", "connecting" or "connecting" mean connecting directly to or connecting through one or more intervening media or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood as the specific circumstances. Moreover, in the following description and for the purpose of explanation, specific nomenclature is set forth to provide a thorough understanding of the various embodiments of the present disclosure. However, it will be apparent to those skilled in the art that the exemplary embodiments can be practiced without these specific details.

[0033] In the process of industrial processing and manufacturing, it is generally required to accurately measure the thickness of the workpiece to be processed for accurate execution of subsequent processing steps. However, there are many types of materials for the workpiece to be processed, and some measuring devices can only measure the workpieces of certain materials, but cannot measure the workpieces of specific materials (for example, transparent materials). Especially in the manufacturing process of semiconductor devices, photolithography equipment needs to accurately measure the thickness of the workpiece to be processed (for example, wafers) to achieve accurate exposure and development. The main function of photolithography equipment is to use optical projection technology to project patterns onto photosensitive materials to form tiny patterns or layers, mainly including the following steps: mask preparation, silicon wafer coating, alignment exposure and development. Before these steps, it is essential to accurately measure the thickness of the wafer to ensure the accuracy of the exposure and development process. At present, optical sensors are generally used to measure the thickness of the workpiece to be processed.

[0034] Figure 1 An example of a thickness measurement device 100 is illustrated. Figure 1 As shown, the light emitting module 105 first emits a beam of light to the workbench 120 and then reflects to the position point A on the light receiving module 110 via the upper surface of the workbench 120. After the workpiece 115 to be processed is placed on the workbench 120, the light emitting module 105 emits another beam of light to the workpiece 115 to be processed and then reflects to the position point B on the light receiving module 110 via the upper surface of the workpiece 115 to be processed. The thickness of the workpiece to be processed can be derived based on the distance between the position point A and the position point B. However, such a method is not suitable for measuring the thickness of a transparent workpiece to be processed. In the actual measurement process, for a transparent workpiece to be processed, the light emitted by the light emitting module 105 will be reflected to the light receiving module 110 via the upper surface and the lower surface of the transparent workpiece to be processed respectively, and the light reflected to the light receiving module 110 from the lower surface interferes with the determination of the thickness of the workpiece to be processed. Only by filtering out the light reflected to the light receiving module 110 via the lower surface can the thickness of the workpiece 115 to be processed be accurately determined, and this may require the introduction of a large number of algorithms for calculation.

[0035] Therefore, there is an urgent need for a thickness measuring device that can accurately measure the thickness of various types of workpieces to be processed (for example, the thickness of transparent workpieces to be processed). The present disclosure proposes a thickness measuring device. The thickness measuring device according to the present disclosure can be applied to measure the thickness of various types of workpieces to be processed (for example, transparent workpieces to be processed) without introducing complex algorithms. The thickness measuring device will be specifically described below in conjunction with the accompanying drawings and some embodiments will be listed for more specific description.

[0036] Figure 2 1 is a schematic diagram illustrating a thickness measurement device 200 according to an embodiment of the present disclosure. The thickness measurement device 200 may include a body ( Figure 2 In one example, the body 205 may be a cylindrical body, a cuboid, or a cube of other regular shapes. Figure 2 As shown, the thickness measuring device 200 may further include a light emitting module 210 for emitting the measuring light and a light receiving module 215 for receiving the measuring light. For example, the light emitting module 210 and the light receiving module 215 may include, but are not limited to: a laser emitting module and a laser receiving module. In some cases, the light emitting module 210 may be opposite to the light receiving module 215. Figure 2 As shown, the thickness measuring device 200 may further include a guide post 220. In one example, the first end of the guide post 220 contacts the workpiece 255 to be processed (for example, when the workpiece 255 to be processed is placed on the workbench 250) or the workbench 250 (for example, when the thickness measuring device 200 is initialized, that is, when the workpiece 255 to be processed is not placed on the workbench 250). In one example, the light emitting module 210 and the light receiving module 215 are arranged relative to each other so that the light emitted by the light emitting module 210 is received by the light receiving module 215 at a predetermined receiving position of the light receiving module 215, wherein the predetermined receiving position depends on the initial receiving position and the thickness of the workpiece 255 to be processed. For example, the initial receiving position may be a position where the light emitted by the light emitting module 210 is received by the light receiving module 215 when the guide post 220 directly presses against the upper surface of the workbench 250. For example, the light receiving module 215 may move with the movement of the lever.

[0037] In one embodiment, Figure 2 As shown, the thickness measuring device 200 may optionally include a lever 240 that rotates along the rotation axis 235. In one example, the first end of the lever 240 is fixed to the light receiving module 215 and the second end of the lever 240 is fixed to the guide post 220. In one example, the lever 240 drives the light receiving module 215 to move up and down. Figure 2As shown, the thickness measuring device 200 may optionally include a telescopic module 230. In one example, a first end of the telescopic module 230 is fixed to a first end of a lever 240 to provide a thrust to the lever 240. In one example, a second end of the telescopic module 230 is fixed to a rigid structure or body. For example, the telescopic module 230 may include, but is not limited to, a spring member.

[0038] In one embodiment, Figure 2 As shown, the thickness measuring device 200 may optionally include an electromagnet 245 located below the lever 240 and between the rotating shaft 235 and the first end of the lever 240. In some cases, the lever 240 may be made of a material that can be adsorbed by the electromagnet, such as but not limited to iron, steel, nickel, alloy, etc. In one example, the electromagnet 245 may be energized to adsorb the first end of the lever 240 to move downward, and the workpiece to be processed may be moved above the workbench 250. In one example, the electromagnet 245 may then be de-energized, and the telescopic module 230 pushes the first end of the lever 240 to move upward, so that the second end of the lever 240 presses against the upper surface of the workpiece to be processed 255, and the light emitting module 210 emits light. In this case, the end of the guide column 220 is a first distance away from the upper surface of the workpiece to be processed 255. Accordingly, the light emitted by the light emitting module 210 is received at a predetermined receiving position (e.g., position point B) of the light receiving module 215.

[0039] In some cases, thickness measurement device 200 may be initialized prior to measurement. Figure 3 The schematic diagram of initializing the thickness measuring device 200 according to an embodiment of the present disclosure is explained. Initializing the thickness measuring device 200 may include: when no workpiece 255 is placed on the workbench 250, the electromagnet 245 is powered off, so that the guide column 220 is pressed against the upper surface of the workbench 250 under the action of the telescopic module 230, as shown in FIG. Figure 3As shown. The light emitting module 210 may then emit light. In this case, the light emitted by the light emitting module 210 is received at the initial receiving position (e.g., position point A) of the light receiving module 215. For example, the thickness measuring device 200 may be initialized before the formal measurement and record the initial receiving position (e.g., position point A) where the light receiving module 215 receives light during initialization, and then the initial receiving position is used as the basis to calculate the thickness of the workpiece to be processed during each formal measurement. In some cases, the thickness measuring device 200 may be initialized before each formal measurement and compare the initial receiving position where the light receiving module 215 receives light during initialization with the predetermined receiving position where the light receiving module 215 receives light during the formal measurement, so as to determine the thickness of the workpiece to be processed based on the initial receiving position and the predetermined receiving position. For example, the distance between the predetermined receiving position and the initial receiving position may be measured by a laser displacement sensor, a grating ruler, a capacitive pressure difference sensor, etc. The following will be combined with Figure 5 The calculation process of determining the thickness of the workpiece to be processed based on the initial receiving position and the predetermined receiving position is described.

[0040] In one embodiment, the thickness measurement device 200 may optionally include a rigid structure ( Figure 2 250). In one example, the rigid structure can fix the body so that the guide post 220 stands on the workbench 250 and contacts the upper surface of the workbench 250. In one example, the movement range of the guide post 220 can depend on the stroke of the telescopic module 230. Preferably, the rigid structure can fix the body so that the guide post 220 stands on the workbench 250 and contacts the workbench 250 when the telescopic module is in a natural state (e.g., not stretched and not compressed). In one example, the range in which the light receiving module 215 can receive light can depend on the stroke of the guide post 220.

[0041] The thickness measuring device 200 according to the present disclosure determines the thickness of the workpiece to be processed based on the distance between the predetermined receiving position and the initial receiving position. The thickness measuring device according to the present disclosure converts the thickness of the workpiece to be processed into the physical stroke of the guide pin, so that it can be applied to measuring the thickness of various types of workpieces to be processed, especially to measuring the thickness of transparent workpieces to be processed.

[0042] Figure 4 The flowchart of the method 400 for measuring the thickness of a workpiece to be processed by the thickness measuring device 200 according to an embodiment of the present disclosure is illustrated. The method 400 may include the following steps.

[0043] In step 405 , the workpiece to be processed may be moved above the workbench.

[0044] In step 410 , the telescopic module may be released so that the guide pillars are pressed against the upper surface of the workpiece under the action of the telescopic module.

[0045] In step 415 , the light emitting module may emit light, wherein the light emitted by the light emitting module is received by the light receiving module at a predetermined receiving position of the light receiving module, and wherein the predetermined receiving position depends on the initial receiving position and the thickness of the workpiece to be processed.

[0046] In one example, method 400 may optionally include: driving the telescopic module so that the guide column is pressed against the upper surface of the workbench under the action of the telescopic module; and emitting light from the light emitting module, wherein the position where the light emitted by the light emitting module is received by the light receiving module is the initial receiving position.

[0047] Those skilled in the art will appreciate that Figure 4 The method 400 is described as an example only, and one or more steps in the method 400 may be omitted or repeated without departing from the scope of the present disclosure.

[0048] The method for measuring the thickness of a workpiece to be processed according to the present disclosure determines the thickness of the workpiece to be processed based on the distance between the predetermined receiving position and the initial receiving position. The method for measuring the thickness of a workpiece to be processed according to the present disclosure converts the thickness of the workpiece to be processed into the physical stroke of the guide pin, and is suitable for measuring the thickness of various types of workpieces to be processed, and is particularly suitable for measuring the thickness of transparent workpieces to be processed.

[0049] Figure 5 The schematic diagram for determining the thickness of a workpiece to be processed according to an embodiment of the present disclosure is explained. The two emitted lights can be simplified as follows Figure 5 As shown. Given that triangle △AOB is similar to triangle △MON and triangle △COB is similar to triangle △PON, MN / AB=NO / OA=PO / OC, it can be deduced that the wafer thickness t=MN=(PO / OC)×AB, where O is the pivot point, PO is the vertical distance from the guide post to the pivot, and OC is the vertical distance from the optical receiving module to the pivot. Both PO and OC are known; AB is the distance between the positions A and B where the optical receiving module receives light, which is also known. If the PO spacing is 20mm, the OC spacing is 100mm, and the AB spacing is 1mm, then MN is (20 / 100)×1=0.2mm, that is, the wafer thickness is 0.2mm.

[0050] Figure 6 FIG. 6 is a schematic diagram illustrating a structure of a lithography apparatus 600 including a thickness measurement device 200 according to an embodiment of the present disclosure. Figure 6 As shown, the lithographic apparatus 600 may include Figure 2 The thickness measuring device 200 shown in FIG.

[0051] The lithography apparatus 600 according to the present disclosure adopts the thickness measuring device 200 as described above. The thickness measuring device 200 determines the thickness of the workpiece to be processed based on the distance between the predetermined receiving position where the light receiving module receives light and the initial receiving position where the light receiving module receives light when the thickness measuring device 200 is initialized. In other words, the thickness measuring device 200 converts the thickness of the workpiece to be processed into the physical stroke of the guide pillar, so that it can be applied to measuring the thickness of various types of workpieces to be processed, and is particularly applicable to measuring the thickness of transparent workpieces to be processed.

[0052] Those skilled in the art will appreciate that Figure 6 This is provided by way of example only and is not intended to be limiting.

[0053] The "range" disclosed herein is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers.

[0054] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0055] In the present application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form new technical solutions. Although the present application has been described with reference to optional embodiments, various improvements can be made thereto and components thereof can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A thickness measuring device, comprising: A body for supporting the thickness measuring device; A light transmitting module for transmitting measurement light; A light receiving module for receiving measurement light; A guide pin, wherein the first end of the guide pin is placed in contact with the surface of the workpiece to be processed, wherein the light emitting module and the light receiving module are arranged relatively to each other so that the light emitted by the light emitting module is received by the light receiving module at a predetermined receiving position B of the light receiving module, and the predetermined receiving position B depends on the initial receiving position A and the thickness MN of the workpiece to be processed; a lever rotating along a rotation axis O, wherein a first end of the lever is fixed to the light receiving module and a second end of the lever is fixed to the guide post; and a telescopic module, a first end of the telescopic module being fixed to the first end of the lever, wherein the telescopic module is a spring; An electromagnet is located below the lever and between the rotating shaft and the first end of the lever, wherein the electromagnet is energized to attract the first end of the lever to move downward, and wherein when the electromagnet is de-energized, the telescopic module pushes the first end of the lever to move upward, so that the second end of the lever is pressed against the upper surface of the workpiece to be processed, wherein the wafer thickness MN = (PO / OC) × AB, wherein AB is the distance between an initial receiving position A and a predetermined receiving position B where the light receiving module receives light, PO is a vertical distance from the guide column to the rotating shaft O, and OC is a vertical distance from the light receiving module to the rotating shaft O.

2. The thickness measuring device according to claim 1, characterized in that: The initial receiving position A is a position where the light emitted by the light emitting module is received by the light receiving module when the guide pillar directly presses against the upper surface of the workbench.

3. The thickness measuring device according to claim 1, characterized in that The distance between the predetermined receiving position B and the initial receiving position A is measured by a laser displacement sensor, a grating ruler, and a capacitive pressure difference sensor.

4. The thickness measuring device according to claim 1, characterized in that: Further including: A rigid structure, wherein the rigid structure fixes the body so that the guide column stands on and contacts the workbench, and wherein the movement range of the guide column depends on the stroke of the telescopic module.

5. A lithographic apparatus comprising the thickness measurement device according to any one of claims 1 to 4.

6. A method for measuring the thickness of a workpiece by using the thickness measuring device according to any one of claims 1 to 4, comprising: Move the workpiece to be processed onto the workbench; Releasing the telescopic module so that the guide pillar is pressed against the upper surface of the workpiece under the action of the telescopic module; as well as The light emitting module emits light, wherein the light emitted by the light emitting module is received by the light receiving module at a predetermined receiving position B of the light receiving module, and wherein the predetermined receiving position B depends on an initial receiving position A and a thickness of the workpiece to be processed.

7. The method according to claim 6, characterized in that Further including: Driving the telescopic module so that the guide column is pressed against the upper surface of the workbench under the action of the telescopic module; as well as The light transmitting module emits light, and a position where the light emitted by the light transmitting module is received by the light receiving module is the initial receiving position A.

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