Wafer transfer device

Abstract

The application provides a wafer conveying device and relates to the technical field of semiconductor manufacturing bodies. The wafer conveying device comprises a base, a placing table, a lifting mechanism, a bearing plate and at least one pressure sensor. The placing table is arranged on the base and used for placing a wafer. The lifting mechanism is arranged on the base and located at one side of the placing table and used for driving the bearing plate to lift. One end of the bearing plate is connected with the lifting mechanism, and the other end of the bearing plate is provided with a bearing part which extends to the placing table. At least three supporting columns are arranged in an array on the bearing part, each of which supports the wafer together and is used for placing the wafer on the placing table. The pressure sensor is arranged on the bearing plate and used for detecting the pressure value borne by the bearing plate. The wafer conveying device provided by the application can determine whether the bearing plate bears the wafer and whether the wafer is offset when the wafer is borne, and the setting form for determining the bearing condition of the bearing plate and determining whether the wafer is offset is simplified, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically, to wafer transfer devices. Background Technology

[0002] In integrated circuit manufacturing, semiconductor wafers are used as carriers for intensive and complex process processing, especially photoresist coating, development, baking and exposure processes, in order to transfer the designed circuits to the wafer.

[0003] During baking and cooling processes, wafers are transported to designated baking or cooling pad areas and kept in good contact with the pads. During this process, due to mechanical motion errors and other factors in existing transport devices, the wafers may shift in position on the transport device, and there is a certain probability that they will not be able to maintain good contact with the pads. This affects the full baking and cooling of the wafers and may not be detected in time, affecting the overall process effect and causing significant losses.

[0004] Existing conveyor systems require configuration at each deformation stage to detect wafer positioning accuracy, which is complex and increases production costs. Summary of the Invention

[0005] This invention provides a wafer transfer device to solve technical problems such as complex wafer inspection setup and reduced production costs.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A wafer transfer device includes a base, a placement stage, a lifting mechanism, a support plate, and at least one pressure sensor. The placement stage is disposed on the base for placing wafers. The lifting mechanism is disposed on the base and located on one side of the placement stage for lifting the support plate. One end of the support plate is connected to the lifting mechanism, and the other end of the support plate has a support portion extending to the placement stage. At least three support columns are arrayed on the support portion, each support column jointly supporting the wafer for placing the wafer on the placement stage. The pressure sensor is disposed on the support plate for detecting the pressure value borne by the support plate.

[0007] Optionally, the pressure sensor is a strain gauge, which is attached to the support plate. When the support column is unloaded, the lifting mechanism moves the support plate up and down, and the strain gauge detects the deformation of the support plate to obtain a corresponding resistance value, thereby determining whether the support column is unloaded. When the support column supports the wafer, the lifting mechanism moves the support plate up and down, and the strain gauge detects the deformation of the support plate to obtain a corresponding resistance value, thereby determining the state of the wafer on the support column.

[0008] Optionally, when the support column is unloaded, the pressure strain gauge detects the deformation of the bearing plate as it rises to obtain a first unloaded resistance value; when the lifting mechanism drives the bearing plate to rise, the pressure strain gauge detects the deformation of the bearing plate to obtain a first resistance value; when the first resistance value is equal to the first unloaded resistance value, it is determined that the support column is unloaded.

[0009] Optionally, when the support column is unloaded, the pressure strain gauge detects the deformation of the bearing plate as it descends to obtain a second unloaded resistance value; when the lifting mechanism drives the bearing plate to descend, the pressure strain gauge detects the deformation of the bearing plate to obtain a second resistance value; when the second resistance value is equal to the two unloaded resistance values, it is determined that the support column is unloaded.

[0010] Optionally, when the wafer is located at the center of the circle formed by each of the support pillars, the pressure strain gauge detects the deformation of the support plate as it rises to obtain a first bearing resistance value; when the lifting mechanism drives the support plate to rise, the pressure strain gauge detects the deformation of the support plate to obtain a first working resistance value; when the first working resistance value is equal to the first bearing resistance value, it is determined that the wafer is located at the center of the circle; when the first working resistance value is not equal to the first bearing resistance value, it is determined that the wafer is located at an off-center position of the circle.

[0011] Optionally, when the wafer is located at the center of the circle formed by each of the support pillars, the pressure strain gauge detects the deformation of the support plate as it descends to obtain a second bearing resistance value; when the lifting mechanism drives the support plate to descend, the pressure strain gauge detects the deformation of the support plate to obtain a second working resistance value. When the second working resistance value is equal to the second bearing resistance value, it is determined that the wafer is located at the center of the circle; when the second working resistance value is not equal to the second bearing resistance value, it is determined that the wafer is located at an off-center position of the circle.

[0012] Optionally, the resistance specification of the pressure strain gauge corresponds to the size specification of the wafer; the larger the wafer size specification, the smaller the resistance specification of the pressure strain gauge.

[0013] Optionally, when the wafer size is between 0 inches and 18 inches, the pressure strain gauge is of 1000Ω-60Ω specification.

[0014] Optionally, when the wafer is 8 inches or less, the pressure strain gauge is of 1000Ω-350Ω specification.

[0015] Optionally, when the wafer size is greater than 8 inches and less than or equal to 18 inches, the pressure strain gauge adopts a 60Ω-350Ω specification.

[0016] This application provides a circular conveying device that uses a lifting mechanism to move a carrier plate up and down so that a wafer supported on a support column can be placed on a placement table. Pressure sensors are installed at any position on the carrier plate to detect the pressure borne by the carrier plate, further determining whether the carrier plate is carrying the wafer and whether the wafer is shifted when carrying the wafer. This simplifies the setting of determining the carrying status of the carrier plate and whether the wafer is shifted, and reduces production costs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the wafer transfer device of this application; Figure 2 This is a schematic diagram of the wafer transfer device of this application for transferring wafers; Figure 3 This is a schematic diagram of the structure of the bearing plate and the pressure sensor in this application. Figure 4 This is a partial structural schematic diagram of the conveying device when the bearing plate of this application is unloaded; Figure 5 This is a partial structural schematic diagram of the conveying device when the carrier plate of this application is under load.

[0019] Icons: 100-Base; 200-Placement platform; 300-Lifting mechanism; 400-Bearing plate; 410-Bearing part; 411-Support column; 500-Pressure sensor; 600-Wafer.

[0020] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0023] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0025] Existing conveying devices require configuration at each deformation stage to detect wafer positioning accuracy, which is complex and increases production costs. To address these issues, embodiments of the present invention provide the following technical solutions to overcome them.

[0026] Please refer to Figures 1 to 3This application provides a wafer 600 transfer device, including a base 100, a placement stage 200, a lifting mechanism 300, a support plate 400, and at least one pressure sensor 500. The placement stage 200 is disposed on the base 100 and is used to place the wafer 600. The lifting mechanism 300 is disposed on the base 100 and located on one side of the placement stage 200, and is used to drive the support plate 400 to lift and lower. One end of the support plate 400 is connected to the lifting mechanism 300, and the other end of the support plate 400 is provided with a support portion 410, which extends to the placement stage 200. At least three support columns 411 are arranged in an array on the support portion 410, and each support column 411 supports the wafer 600 together, for placing the wafer 600 on the placement stage 200. The pressure sensor 500 is disposed on the support plate 400 and is used to detect the pressure value borne by the support plate 400.

[0027] Specifically, a placement stage 200 is mounted on a base 100. A lifting mechanism 300 is mounted on the base 100 and located on one side of the placement stage 200. One end of a support plate 400 is connected to the lifting mechanism 300, and the other end is provided with a support portion 410, extending to the placement stage 200. The support column 411 on the support portion 410 can support the wafer 600. The lifting mechanism 300 drives the support plate 400 to move up and down, so that the wafer 600 on the support column 411 can be placed on the placement stage 200. Furthermore, a pressure sensor 500 is provided on the support plate 400. The pressure sensor can detect the pressure value borne by the support plate 400, monitor the pressure change of the support plate 400 in real time, and thus determine whether the wafer 600 is offset and whether the support plate 400 is unloaded.

[0028] It should be noted that the pressure sensor 500 can be set at any position on the carrier plate 400, and can detect the pressure value borne by the carrier plate 400, monitor the pressure change of the carrier plate 400 in real time, thereby determining whether the wafer 600 is offset and whether the carrier plate 400 is unloaded.

[0029] This application provides a circular conveying device. A lifting mechanism 300 drives a support plate 400 to move up and down, so that a wafer 600 supported on a support column 411 is placed on a placement stage 200. A pressure sensor 500 is set at any position on the support plate 400 to detect the pressure borne by the support plate 400, and further determine whether the support plate 400 is carrying the wafer 600, and whether the wafer 600 is offset when carrying the wafer 600. This simplifies the setting of judging the carrying status of the support plate 400 and judging whether the wafer 600 is offset, and reduces production costs.

[0030] In the embodiments of this application, the pressure sensor 500 is a pressure strain gauge, which is attached to the support plate 400. When the support column 411 is unloaded, the lifting mechanism 300 drives the support plate 400 to move up and down, and the pressure strain gauge detects the deformation of the support plate 400 to obtain the corresponding resistance value, thereby determining whether the support column 411 is unloaded. When the support column 411 supports the wafer 600, the lifting mechanism 300 drives the support plate 400 to move up and down, and the pressure strain gauge detects the deformation of the support plate 400 to obtain the corresponding resistance value, thereby determining the state of the wafer 600 on the support column 411.

[0031] Specifically, strain gauges are attached to the carrier plate 400. During the transfer of the wafer 600, the lifting mechanism 300 moves the carrier plate 400 up and down. The strain gauges detect the deformation of the carrier plate 400 and obtain its resistance value. Based on the resistance value, it is determined whether the carrier plate 400 is unloaded and whether the wafer 600 on the support column 411 has shifted. When the deformation detected by the strain gauge is small and the resistance value changes little, the carrier plate 400 is determined to be unloaded, prompting the operator to check the equipment's unload status, thus preventing resource waste caused by unloaded operation. When the deformation detected by the strain gauge is large and the resistance value changes significantly, the carrier plate 400 is determined to be under load, and the resistance value is used to determine whether the wafer 600 has shifted. If the wafer 600 has shifted, the operator is prompted to stop the equipment and adjust the position of the wafer 600 to prevent the shifted wafer 600 from affecting subsequent processes, thereby improving the overall production efficiency of the semiconductor manufacturing process.

[0032] It should be noted that the pressure strain gauge is mainly a pressure sensor 500 that uses an elastic sensitive element (elastic body) and a strain gauge (resistance strain gauge) to convert the measured pressure into a corresponding change in resistance value.

[0033] Please refer to Figures 1 to 5 In the embodiments of this application, when the support column 411 is unloaded, the pressure strain gauge detects the deformation of the bearing plate 400 when it rises to obtain a first unloaded resistance value; when the lifting mechanism 300 drives the bearing plate 400 to rise, the pressure strain gauge detects the deformation of the bearing plate 400 to obtain a first resistance value; when the first resistance value is equal to the first unloaded resistance value, it is determined that the support column 411 is unloaded.

[0034] Specifically, when the support column 411 is unloaded, the lifting mechanism 300 drives the bearing plate 400 to move upward. During this process, the pressure strain gauge detects the deformation of the bearing plate 400, that is, the bending or stretching of the bearing plate 400 caused by the load change on the support column 411. The deformation of the bearing plate 400 will cause the resistance value of the pressure strain gauge to change, and obtain the first unloaded resistance value. During the operation of the lifting mechanism 300, the lifting mechanism 300 drives the bearing plate 400 to move upward. At this time, the pressure strain gauge will obtain the first resistance value. The first resistance value is compared with the first unloaded resistance value. When the first resistance value and the first unloaded resistance value are equal, it is determined that the bearing plate 400 is operating under no-load conditions.

[0035] In the embodiments of this application, when the support column 411 is unloaded, the pressure strain gauge detects the deformation of the bearing plate 400 when it descends to obtain a second unloaded resistance value; when the lifting mechanism 300 drives the bearing plate 400 to descend, the pressure strain gauge detects the deformation of the bearing plate 400 to obtain a second resistance value; when the second resistance value is equal to the second unloaded resistance value, it is determined that the support column 411 is unloaded.

[0036] Specifically, when the support column 411 is unloaded, the lifting mechanism 300 drives the bearing plate 400 to move downwards. During this process, the pressure strain gauge detects the deformation of the bearing plate 400, that is, the bending or stretching of the bearing plate 400 caused by the load change on the support column 411. The deformation of the bearing plate 400 will cause the resistance value of the pressure strain gauge to change, resulting in a second unloaded resistance value. During the operation of the lifting mechanism 300, the lifting mechanism 300 drives the bearing plate 400 to move downwards. At this time, the pressure strain gauge will obtain a second resistance value. The second resistance value is compared with the second unloaded resistance value. When the second resistance value and the second unloaded resistance value are equal, it is determined that the bearing plate 400 is operating under no-load conditions.

[0037] In the embodiments of this application, when the wafer 600 is located at the center of the circle formed by each of the support pillars 411, the pressure strain gauge detects the deformation of the support plate 400 when it rises to obtain a first bearing resistance value; when the lifting mechanism 300 drives the support plate 400 to rise, the pressure strain gauge detects the deformation of the support plate 400 to obtain a first working resistance value. When the first working resistance value is equal to the first bearing resistance value, it is determined that the wafer 600 is located at the center of the circle; when the first working resistance value is not equal to the first bearing resistance value, it is determined that the wafer 600 is located at an off-center position of the circle.

[0038] Specifically, the wafer 600 transfer device uses strain gauges to precisely detect the position of the wafer 600 on the support pillars 411. The strain gauges, mounted on the support plate 400, convert the deformation of the support plate 400 when supported by the support pillars 411 into a change in resistance. When the wafer 600 is at the center of the circle formed by the support pillars 411, the deformation caused by the rise of the support plate 400 generates a preset first bearing resistance value. During the lifting process of the lifting mechanism 300, which raises the support plate 400, the strain gauges detect deformation in real time, generating a first working resistance value. By comparing the first working resistance value and the first bearing resistance value, the device can determine whether the wafer 600 is at the center of the circle: if the two resistance values ​​are equal, the wafer 600 is centered; if they are not equal, the wafer 600 is off-center. This automatic detection and comparison process allows the wafer 600 transfer device to accurately determine the position of the wafer 600 and make adjustments as necessary to ensure the correct placement of the wafer 600, thereby improving production efficiency and transfer accuracy.

[0039] In the embodiments of this application, when the wafer 600 is located at the center of the circle formed by each of the support pillars 411, the pressure strain gauge detects the deformation of the support plate 400 when it descends to obtain a second bearing resistance value; when the lifting mechanism 300 drives the support plate 400 to descend, the pressure strain gauge detects the deformation of the support plate 400 to obtain a second working resistance value. When the second working resistance value is equal to the second bearing resistance value, it is determined that the wafer 600 is located at the center of the circle; when the second working resistance value is not equal to the second bearing resistance value, it is determined that the wafer 600 is located at an off-center position of the circle.

[0040] Specifically, the wafer 600 transfer device uses strain gauges to detect the deformation of the carrier plate 400 during its lifting and lowering process, thereby determining whether the wafer 600 is correctly placed at the center of the circle formed by the support columns 411. Specifically, when the wafer 600 is at the center of the circle, the deformation caused by the descent of the carrier plate 400 is detected by the strain gauges and recorded as a second bearing resistance value. During the descent of the carrier plate 400 by the lifting mechanism 300, the strain gauges detect the deformation in real time and generate a second working resistance value. By comparing the second working resistance value with a preset second bearing resistance value, the device can determine whether the wafer 600 is centered: if the resistance values ​​are equal, it indicates that the wafer 600 is centered; if the resistance values ​​are unequal, it indicates that the wafer 600 is off-center. This automatic detection and comparison process allows the wafer 600 transfer device to accurately determine the position of the wafer 600 and make adjustments when necessary to ensure the correct placement of the wafer 600, thereby improving production efficiency and transfer accuracy.

[0041] In the embodiments of this application, the resistance specification of the pressure strain gauge corresponds to the size specification of the wafer 600. The larger the size specification of the wafer 600, the smaller the resistance specification of the pressure strain gauge.

[0042] Specifically, the resistance value of the strain gauge is matched to the size of the wafer 600, enabling a precise wafer 600 position detection mechanism. Its working principle is as follows: the resistance value of the strain gauge is adjusted according to the size of the wafer 600; the larger the wafer 600, the smaller the resistance value of the strain gauge. Thus, when the lifting mechanism 300 moves the support plate 400 up or down, the strain gauge can detect different resistance values ​​based on the deformation changes of the support plate 400. This method of adjusting the resistance value of the strain gauge according to the wafer 600 size not only improves the intelligence level of the wafer 600 conveying device but also enhances the overall efficiency and accuracy of the production line.

[0043] It should be noted that the resistance value of a pressure strain gauge directly affects its sensitivity. A pressure strain gauge with a higher resistance value exhibits a larger change in resistance (ΔR) under the same strain, thus generating a larger output signal in the measurement circuit. This helps improve the signal-to-noise ratio of the measurement system, thereby increasing sensitivity. Conversely, a pressure strain gauge with a lower resistance value exhibits a smaller change in resistance (ΔR) under the same strain, resulting in a smaller output signal. This may require more sensitive measuring equipment to detect these changes, potentially reducing the overall sensitivity of the system.

[0044] In the embodiments of this application, when the size of the wafer 600 is between 0 inches and 18 inches, the pressure strain gauge adopts a specification of 1000Ω-60Ω.

[0045] Specifically, the resistance rating of the strain gauge corresponds to the size of the wafer 600; the larger the wafer 600, the smaller the resistance of the strain gauge. Within the range of 0 inches to 18 inches, the resistance rating decreases from 1000Ω to 60Ω. Thus, when the lifting mechanism 300 moves the support plate 400 up and down, the strain gauge can adjust its resistance according to the different deformations caused by wafers of different sizes. By adjusting the resistance of the strain gauge, the device can adapt to wafers of different sizes, ensuring accurate detection, optimizing the performance of the wafer 600 transport device, reducing detection errors, enhancing reliability, and simplifying maintenance, thereby improving the overall efficiency and accuracy of the production line.

[0046] In embodiments of this application, when the wafer 600 is 8 inches or less, the pressure strain gauge uses a 1000Ω-350Ω specification. When the wafer 600 is larger than 8 inches but less than or equal to 18 inches, the pressure strain gauge uses a 60Ω-350Ω specification.

[0047] Specifically, the resistance rating of the pressure strain gauge corresponds to the size of the wafer 600; the larger the wafer 600, the smaller the resistance of the strain gauge. For example, when the wafer 600 is 8 inches or less, the strain gauge uses a 1000Ω-350Ω rating; when the wafer 600 is larger than 8 inches but smaller than or equal to 18 inches, the strain gauge uses a 60Ω-350Ω rating. This design allows the pressure strain gauge to change its resistance according to the different deformations caused by wafers 600 of different sizes when the lifting mechanism 300 moves the carrier plate 400 up and down, thus accurately detecting the position and state of the wafer 600. This improves the adaptability and detection accuracy of the wafer 600 transport device to wafers of different sizes, optimizes the performance of the wafer 600 transport device, reduces detection errors caused by size mismatch, improves production efficiency, and reduces production costs because a suitable strain gauge can be selected according to the size of the wafer 600, reducing material waste.

[0048] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A wafer transfer device, characterized in that, It includes a base, a placement stage, a lifting mechanism, a support plate, and at least one pressure sensor; the placement stage is disposed on the base and is used to place the wafer. The lifting mechanism is mounted on the base and located on one side of the placement platform, and is used to drive the support plate to rise and fall. One end of the support plate is connected to the lifting mechanism, and the other end of the support plate is provided with a support part that extends to the placement platform; The carrier portion is provided with at least three support pillars arranged in an array, each of which together supports the wafer and is used to place the wafer on the placement stage; The pressure sensor is mounted on the support plate and is used to detect the pressure value borne by the support plate.

2. The wafer transfer device according to claim 1, characterized in that, The pressure sensor is a pressure strain gauge, which is attached to the support plate. When the support column is unloaded, the lifting mechanism drives the bearing plate to move up and down, and the pressure strain gauge detects the deformation of the bearing plate to obtain the corresponding resistance value, so as to determine whether the support column is unloaded. When the support column supports the wafer, the lifting mechanism drives the carrier plate to move up and down, and the pressure strain gauge detects the deformation of the carrier plate to obtain the corresponding resistance value, so as to determine the state of the wafer on the support column.

3. The wafer transfer device according to claim 2, characterized in that, When the support column is unloaded, the pressure strain gauge detects the deformation of the bearing plate as it rises to obtain the first unloaded resistance value. When the lifting mechanism drives the bearing plate to rise, the pressure strain gauge detects the deformation of the bearing plate to obtain a first resistance value. When the first resistance value is equal to the first no-load resistance value, it is determined that the support column is no-load.

4. The wafer transfer device according to claim 2, characterized in that, When the support column is unloaded, the pressure strain gauge detects the deformation of the bearing plate as it descends to obtain a second unloaded resistance value. When the lifting mechanism drives the bearing plate to descend, the pressure strain gauge detects the deformation of the bearing plate to obtain a second resistance value. When the second resistance value is equal to the two unloaded resistance values, it is determined that the support column is unloaded.

5. The wafer transfer device according to claim 2, characterized in that, When the wafer is positioned at the center of the circle formed by each of the support pillars, the pressure strain gauge detects the deformation of the support plate as it rises to obtain a first load-bearing resistance value. When the lifting mechanism drives the support plate to rise, the pressure strain gauge detects the deformation of the support plate to obtain a first working resistance value. When the first working resistance value is equal to the first support resistance value, it is determined that the wafer is located at the center of the circle. When the first working resistance value is not equal to the first support resistance value, it is determined that the wafer is located at an off-center position of the circle.

6. The wafer transfer device according to claim 2, characterized in that, When the wafer is positioned at the center of the circle formed by each of the support pillars, the pressure strain gauge detects the deformation of the bearing plate as it descends to obtain a second bearing resistance value. When the lifting mechanism drives the support plate to descend, the pressure strain gauge detects the deformation of the support plate to obtain a second working resistance value. When the second working resistance value is equal to the second support resistance value, it is determined that the wafer is located at the center of the circle. When the second working resistance value is not equal to the second support resistance value, it is determined that the wafer is located at an off-center position of the circle.

7. The wafer transfer apparatus according to any one of claims 2-6, characterized in that, The resistance rating of the strain gauge corresponds to the size of the wafer; the larger the wafer size, the smaller the resistance rating of the strain gauge.

8. The wafer transfer apparatus according to claim 7, characterized in that, When the wafer size is between 0 inches and 18 inches, the pressure strain gauge is of specification 1000Ω-60Ω.

9. The wafer transfer apparatus according to claim 8, characterized in that, When the wafer is 8 inches or less, the pressure strain gauge is of 1000Ω-350Ω specification.

10. The wafer transfer apparatus according to claim 8, characterized in that, When the size of the wafer is greater than 8 inches and less than or equal to 18 inches, the pressure strain gauge adopts a specification of 60Ω-350Ω.

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