Square wafer sensor positioning system

Abstract

This invention relates to the field of wafer positioning technology, specifically to a sensor-based positioning system for square wafers. The system includes: a horizontal moving platform, on which a rotating platform is mounted; multiple wafer positioning pins on the rotating platform for supporting the square wafer; multiple positioning sensors fixedly mounted on the exterior of the horizontal moving platform at different positions on its periphery for detecting the actual coverage distance of the square wafer relative to the positioning sensors; and a positioning control module that determines the actual position of the square wafer based on the actual coverage distance and a preset standard coverage distance, controlling the horizontal moving platform to move horizontally and / or controlling the rotating platform to rotate. The use of non-contact sensor detection avoids direct friction and wear of components such as bearings and gears in traditional mechanical alignment systems, reducing maintenance frequency and replacement costs due to component aging, and minimizing mechanical wear and maintenance requirements.

Description

Technical Field

[0001] This invention relates to a square wafer sensor-type positioning system, belonging to the field of wafer positioning technology. Background Technology

[0002] In Equipment Front End Module (EFEM) systems, the wafer aligner unit is a critical component ensuring precise alignment of the wafer during transport and processing. However, in practical applications of traditional solutions, mechanical wafer aligner units may have the following drawbacks and limitations:

[0003] Mechanical components are prone to wear and loosening during long-term operation, requiring regular maintenance and replacement. For example, wear on components such as motor bearings and transmission gears can affect alignment accuracy, necessitating timely replacement. This makes the maintenance cost of mechanical wafer aligner units relatively high, and this cost may gradually increase with the equipment's usage time. Furthermore, due to wear and aging of mechanical components, mechanical wafer aligner units may require more frequent calibration and adjustment. This not only increases labor costs but may also lead to increased production line downtime, impacting production efficiency and output, and indirectly increasing operating costs. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a square wafer sensor-based positioning system.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a square wafer sensor positioning system, including a horizontal moving platform, multiple positioning sensors, and a positioning control module;

[0006] The horizontal moving platform is capable of moving in the horizontal direction, and the horizontal moving platform carries a rotating platform;

[0007] The rotating platform is provided with a plurality of wafer positioning pins, which are used to support square wafers;

[0008] The plurality of positioning sensors are fixedly installed on the outside of the horizontal moving platform and located at different positions on the outer periphery of the horizontal moving platform, and are used to detect the actual coverage distance of the square wafer to the positioning sensors;

[0009] The positioning control module determines the actual position of the square wafer based on the actual coverage distance and the preset standard coverage distance, and controls the horizontal moving platform to move horizontally and / or controls the rotating platform to rotate based on the actual position.

[0010] The beneficial effects of this invention are: 1. The system uses non-contact sensor detection, which avoids the direct friction and wear of components such as bearings and gears in traditional mechanical alignment devices, thereby reducing the maintenance frequency and replacement cost caused by component aging, and reducing mechanical wear and maintenance requirements overall.

[0011] 2. Position correction is achieved through automatic control of the horizontal moving platform and the rotating platform, reducing the need for manual calibration and adjustment, saving labor and operating costs, reducing production line downtime, and improving production efficiency.

[0012] 3. The actual position of the wafer is calculated in real time based on sensor data and precise adjustments are made, reducing alignment errors caused by mechanical loosening or wear, and improving the reliability and long-term stability of the system.

[0013] 4. Multiple sensors are distributed in different locations, which can effectively adapt to the shape characteristics of square wafers, achieve fast and accurate positioning, and simplify the operation process.

[0014] Based on the above technical solution, the present invention can be further improved as follows:

[0015] Furthermore, the plurality of positioning sensors include: a first positioning sensor, a second positioning sensor, and a third positioning sensor;

[0016] The first positioning sensor is disposed on one side of the preset movement direction of the horizontal moving platform, and is oriented towards the side of the preset movement direction;

[0017] The second positioning sensor and the third positioning sensor are respectively disposed on both sides of the preset movement direction, and are oriented in the preset movement direction.

[0018] Furthermore, the first positioning sensor is positioned in front of the second and third positioning sensors along the preset moving direction;

[0019] The first positioning sensor is farther away from the axis of the preset movement direction than the second positioning sensor and the third positioning sensor.

[0020] The advantages of adopting the above-mentioned further solution are: it enables the three positioning sensors to detect the prismatic wafer mounted on the rotating platform from different angles and positions. Through the coordinated operation of the three positioning sensors, the actual coverage distance of the prismatic wafer relative to the positioning sensors can be obtained more accurately, thus providing more accurate and detailed data support for the positioning control module to determine the actual position of the prismatic wafer. At the same time, this layout enhances the system's adaptability to prismatic wafers of different sizes and placement states, ensuring efficient and accurate positioning under various conditions, further improving the performance and stability of the prismatic wafer sensor-based positioning system.

[0021] Furthermore, the positioning control module acquires the first actual coverage distance, the second actual coverage distance, and the third actual coverage distance corresponding to the first positioning sensor, the second positioning sensor, and the third positioning sensor, as well as the first standard coverage distance, the second standard coverage distance, and the third standard coverage distance corresponding to each of them.

[0022] The distance difference between the second actual coverage distance and the third actual coverage distance is compared with the distance difference between the second standard coverage distance and the third standard coverage distance, so as to control the rotating platform to rotate according to the comparison result and the preset standard difference range;

[0023] For the second or third positioning sensor, determine the distance difference between its actual coverage distance and its corresponding standard coverage distance, and compare the distance difference with a preset standard deviation range to control the horizontal moving platform to move horizontally based on the comparison result;

[0024] The distance difference between the first actual coverage distance and the first standard coverage distance is determined, and the distance difference is compared with a preset standard deviation range, so as to control the rotating platform to rotate according to the comparison result.

[0025] The beneficial effects of adopting the above-mentioned further solution are as follows: By conducting multi-dimensional comparative analysis of the actual coverage distance and standard coverage distance obtained by the three positioning sensors, the positional deviation of the prismatic wafer in the horizontal and rotational directions can be comprehensively and accurately determined. Based on the data comparison results from different sensors, the rotation platform and the horizontal movement platform are controlled separately, achieving fine-tuning of the prismatic wafer's position and ensuring that the prismatic wafer accurately reaches the preset standard position. This intelligent control method based on multi-sensor data greatly improves the accuracy and automation of positioning, reduces manual intervention and errors, further enhances the system's working efficiency and stability, reduces production costs and maintenance difficulty, and makes the prismatic wafer sensor-based positioning system more adaptable and reliable in practical applications.

[0026] Furthermore, the positioning control module determines the first actual distance difference between the second actual coverage distance and the third actual coverage distance, and the first standard distance difference between the second standard coverage distance and the third standard coverage distance;

[0027] If the difference between the absolute value of the first actual distance difference and the absolute value of the first standard distance difference exceeds the preset standard difference range, then the corresponding rotation direction is selected according to the positive or negative value of the first actual distance difference, and the rotating platform is controlled to rotate.

[0028] Furthermore, the positioning control module determines, for the second positioning sensor or the third positioning sensor, a first actual-standard distance difference between the corresponding actual coverage distance and the corresponding standard coverage distance;

[0029] The first actual-standard distance difference is compared with a preset standard deviation range. If the first actual-standard distance difference exceeds the preset standard deviation range, the horizontal moving platform is controlled to move horizontally according to the positive or negative value of the first actual-standard distance difference, so as to move closer to or further away from the positioning sensor used to calculate the first actual-standard distance difference.

[0030] Furthermore, the positioning control module determines a second actual-standard distance difference between the first actual coverage distance and the first standard coverage distance;

[0031] The second actual-standard distance difference is compared with a preset standard deviation range. If the second actual-standard distance difference exceeds the preset standard deviation range, the horizontal moving platform is controlled to move horizontally to move closer to or further away from the first positioning sensor, depending on the positive or negative value of the second actual-standard distance difference.

[0032] The beneficial effect of adopting the above-mentioned further scheme is that it provides a precise basis for the control of the horizontal moving platform through a clear difference calculation and comparison mechanism. This control method based on the actual-standard distance difference can adjust the position of the horizontal moving platform in a timely and accurate manner according to the specific deviation of the square wafer in the horizontal direction.

[0033] Furthermore, the preset standard deviation range is [-0.1mm, 0.1mm].

[0034] Furthermore, the positioning control module, after controlling the rotating platform to rotate or controlling the horizontal moving platform to move horizontally, repeatedly executes the comparison process of the current positioning step.

[0035] Furthermore, before receiving the actual coverage distance sent by the positioning sensor, the positioning control module determines that the horizontal moving platform has reached the preset zero point position and carries the new square wafer, reaching the preset working position corresponding to the positioning control module.

[0036] The beneficial effect of adopting the above-mentioned further solution is that it ensures the system is in the correct initial state before starting the positioning operation, laying the foundation for accurate positioning work afterwards. Only when the horizontal moving platform reaches the preset zero point position and carries the new square wafer to the preset working position is the actual coverage distance data received by the positioning control module meaningful. Only then can the actual position of the square wafer be accurately determined based on this data, and effective position adjustments be made. Attached Figure Description

[0037] Figure 1 This is a top view of the square wafer sensor-type positioning system in an embodiment of this application;

[0038] Figure 2 This is a three-dimensional schematic diagram of the square wafer sensor-type positioning system in the embodiments of this application;

[0039] Figure 3 This is a flowchart illustrating the positioning control method of the square wafer sensor-type positioning system in an embodiment of this application.

[0040] Among them, 101 is a horizontal moving platform, 1021 is a first positioning sensor, 1022 is a second positioning sensor, 1023 is a third positioning sensor, 103 is a rotating platform, 104 is a wafer positioning pin, and 105 is a square wafer. Detailed Implementation

[0041] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0043] like Figure 1 and Figure 2 As shown, this application embodiment provides a square wafer sensor-type positioning system, including a horizontal moving platform 101, multiple positioning sensors, and a positioning control module (not shown in the figure).

[0044] The horizontal moving platform 101 is capable of moving horizontally, and a rotating platform 103 is mounted on the horizontal moving platform 101. The horizontal moving platform 101 can be controlled by a corresponding mechanical transmission mechanism to move in the horizontal XY direction, hence it can also be called an XY moving platform. The rotating platform 103 is mounted on top of the horizontal moving platform 101; the two can be integrated as one unit or detached.

[0045] The rotating platform 103 is provided with a plurality of wafer positioning pins 104, which are used to support the square wafers 105. The rotating platform 103 can rotate relative to the horizontal moving platform 101, including clockwise and counterclockwise rotation.

[0046] The wafer positioning pins 104, also known as PIN pins, secure the wafer to the rotating platform 103 using mechanical vacuum adsorption or electrostatic adsorption technology. The vacuum adsorption system provides uniform support points through the PIN pins, ensuring the wafer remains flat during processing and preventing bending or breakage due to uneven stress. Figure 1 and Figure 2 As shown in the embodiment of this application, four wafer positioning pins 104 are evenly arranged on the rotating platform 103. When the rotating platform 103 rotates, the square wafer 105 it carries rotates synchronously through the wafer positioning pins 104.

[0047] Multiple positioning sensors are fixedly mounted on the outside of the horizontal moving platform 101, at different positions on its outer periphery, to detect the actual coverage distance of the square wafer 105 relative to the positioning sensors. For example... Figure 1 and Figure 2 As shown, the positioning sensor can be installed outside the horizontal moving platform 101 through a bracket or other structure, and does not contact the horizontal moving platform 101.

[0048] During normal operation, the square wafer 105, mounted on the horizontal moving platform 101 via the rotating platform 103 and wafer positioning pins 104, is moved to the corresponding working position, where multiple positioning sensors are installed. Based on a pre-set moving distance, the position of the square wafer 105 is kept within a general range. At this time, as... Figure 1 As shown, in a top-down view, the positioning sensor is located at the edge of the square wafer 105. It can detect the distance value of the square wafer 105 itself being obscured by the square wafer 105, and this distance value also represents the distance difference between the edge of the square wafer 105 and the inner edge of the positioning sensor.

[0049] Furthermore, such as Figure 1 and Figure 2As shown, the multiple positioning sensors include: a first positioning sensor 1021, a second positioning sensor 1022, and a third positioning sensor 1023. In actual operation, a greater number of positioning sensors can be set according to requirements.

[0050] The first positioning sensor 1021 is disposed on one side of the preset movement direction of the horizontal moving platform 101, and its orientation is also on the side of the preset movement direction. The preset movement direction refers to the movement direction of the horizontal moving platform 101 when it moves the square wafer 105 to the working position. For ease of description, it is assumed here that the preset movement direction is the Y direction in the horizontal direction. In this case, the orientation of the first positioning sensor 1021 is on the side of the Y direction, that is, its orientation is the X direction.

[0051] The second positioning sensor 1022 and the third positioning sensor 1023 are respectively disposed on both sides of the preset movement direction, and their orientation is the preset movement direction. In this embodiment, their orientation is the Y direction.

[0052] At this time, the second positioning sensor 1022 and the third positioning sensor 1023 are oriented in the Y direction, and can detect whether the distance of the square wafer 105 in the Y direction is appropriate. Simultaneously, they are positioned on both sides, and can detect whether the shape of the square wafer 105 on the rotating platform 103 is symmetrical about the preset movement direction (Y direction). The first positioning sensor 1021 is oriented in the X direction, and can detect whether the distance of the square wafer 105 in the X direction is appropriate.

[0053] In addition, such as Figure 1 and Figure 2 As shown, the first positioning sensor 1021 is positioned in front of the second positioning sensor 1022 and the third positioning sensor 1023 along the preset moving direction, that is, in front of the Y direction. This allows the positioning control system to first detect the Y-direction distance and the symmetrical direction distance corresponding to the second positioning sensor 1022 and the third positioning sensor 1023, and then detect the X-direction distance.

[0054] Compared to the second positioning sensor 1022 and the third positioning sensor 1023, the first positioning sensor 1021 is farther away from the axis of the preset movement direction, which makes it easier for the first positioning sensor 1021 to effectively detect the distance in the X direction.

[0055] The positioning control module determines the actual position of the square wafer 105 based on the actual coverage distance and the preset standard coverage distance. Based on this actual position, it controls the horizontal moving platform 101 to move horizontally and / or controls the rotating platform 103 to rotate. The positioning control module (not shown in the figure) can be a microcontroller, single-board computer, or other device with corresponding computing capabilities. It can interact with the positioning sensor to obtain the corresponding actual coverage distance and perform relevant calculations. It can also interact with the transmission mechanisms in the horizontal moving platform 101 and the rotating platform 103, controlling the horizontal movement of the horizontal moving platform 101 and the rotation of the rotating platform 103 by controlling these transmission mechanisms.

[0056] like Figure 3 As shown, before receiving the actual coverage distance sent by the positioning sensor, the positioning control module determines that the horizontal moving platform 101 has reached the preset zero point position (also known as zeroing), and carries the new square wafer 105 to reach the preset working position corresponding to the positioning control module. Specifically, the horizontal moving platform 101 places the new square wafer 105 at the preset zero point position and carries it to the preset working position, thereby performing positioning control of the new square wafer 105.

[0057] When performing positioning control, the positioning control module acquires the first actual coverage distance S1_Real, the second actual coverage distance S2_Real, and the third actual coverage distance S3_Real corresponding to the first positioning sensor 1021, the second positioning sensor 1022, and the third positioning sensor 1023, respectively, as well as their respective first standard coverage distances S1_Stand, S2_Stand, and S3_Stand. Among these, if according to... Figure 1 The second positioning sensor 1022 and the third positioning sensor 1023 are arranged in a symmetrical manner, and the values ​​of the second standard coverage distance S2_Stand and the third standard coverage distance S3_Stand can be set to be equal.

[0058] In Example 1, the distance difference between the second actual coverage distance and the third actual coverage distance is compared with the distance difference between the second standard coverage distance and the third standard coverage distance. Based on the comparison result and the preset standard difference range, the rotating platform is controlled to rotate.

[0059] This embodiment is mainly used for positioning control of the symmetry of the square wafer 105. The positioning control module determines the first actual distance difference Sub1_Real between the second actual coverage distance S2_Real and the third actual coverage distance S3_Real. For convenience of calculation, the absolute value of the first actual distance difference Sub1_Real can be selected for calculation. Similarly, the first standard distance difference Sub1_Stand between the second standard coverage distance S2_Stand and the third standard coverage distance S3_Stand is determined, and its absolute value is selected for calculation.

[0060] If the difference between the absolute value of the first actual distance difference Sub1_Real and the absolute value of the first standard distance difference Sub1_Stand exceeds the preset standard difference range, the corresponding rotation direction is selected according to the positive or negative value of the first actual distance difference Sub1_Real, and the rotation platform is controlled to rotate. For example, the preset standard difference range is set to [-0.1mm, 0.1mm]. At this time, if Sub1_Stand – 0.1 < Sub1_Real < Sub1_Stand + 0.1, it is considered to meet the preset standard difference range, and there is no need to control the rotation platform 103 to rotate. Otherwise, the rotation platform 103 is controlled to rotate. Among them, the corresponding rotation direction can be selected according to the positive or negative value of the first actual distance difference, so as to Figure 1 take as an example. When the first actual distance difference is positive, that is, the second actual coverage distance S2_Real is greater than the third actual coverage distance S3_Real, it means that the square wafer 105 is tilted downward to the left. At this time, the rotation platform 103 should be controlled to rotate clockwise; on the contrary, if the first actual distance difference is negative, the rotation platform 103 is controlled to rotate counterclockwise. Of course, the rotation direction here can be adjusted based on the calculation method of the first actual distance difference and the layout method of the positioning sensors, and is not limited to the clockwise and counterclockwise determination methods in this embodiment.

[0061] In Embodiment 2, for the second positioning sensor 1022 or the third positioning sensor 1023, the distance difference between the corresponding actual coverage distance and the corresponding standard coverage distance is determined, and the horizontal moving platform is controlled to move horizontally according to the comparison between the distance difference and the preset standard difference range.

[0062] This embodiment is mainly used for positioning control of the distance in the Y direction of the square wafer 105. For the second positioning sensor 1022 or the third positioning sensor 1023, the first actual-standard distance difference between the corresponding actual coverage distance and the corresponding standard coverage distance is determined.

[0063] In this embodiment, since the second positioning sensor 1022 and the third positioning sensor 1023 are symmetrically designed, any one of the positioning sensors can be selected for calculation. For the convenience of description, the second positioning sensor 1022 can be selected in this embodiment to determine the first actual-standard distance difference between the corresponding second actual coverage distance S2_Real and the corresponding standard coverage distance S2_Stand.

[0064] Compare the first actual-standard distance difference with the preset standard difference range. If the first actual-standard distance difference exceeds the preset standard difference range, control the horizontal moving platform 101 to move horizontally according to the positive or negative value of the first actual-standard distance difference, so as to approach or move away from the positioning sensor used to calculate the first actual-standard distance difference.

[0065] Still taking the preset standard difference range of [-0.1mm, 0.1mm] as an example, at this time, it is necessary to calculate whether S2_Stand–0.1 < S2_Real < S2_Stand + 0.1 is satisfied. If it is satisfied, no control adjustment is required. If it is not satisfied, it means that the distance of the square wafer in the Y direction needs to be adjusted, and the adjustment is made according to the positive or negative value of the first actual-standard distance difference. For Figure 1 example, if the first actual-standard distance difference is positive, that is, the second actual coverage distance S2_Real is greater than the second standard coverage distance S2_Stand, it is considered that it is too close to the second positioning sensor 1022 at this time, and the horizontal moving platform 101 can be controlled to move horizontally away from the second positioning sensor 1022 used to calculate the first actual-standard distance difference; on the contrary, if the first actual-standard distance difference is negative, the horizontal moving platform 101 can be controlled to move horizontally closer to the second positioning sensor 1022.

[0066] Embodiment 3: Determine the distance difference between the first actual coverage distance and the first standard coverage distance, and compare it with the preset standard difference range according to this distance difference, so as to control the rotation platform to rotate according to the comparison result.

[0067] This embodiment is mainly used for positioning control of the distance of the square wafer 105 in the X direction, and determining the second actual-standard distance difference between the first actual coverage distance S1_Real and the first standard coverage distance S1_Stand.

[0068] Compare the second actual-standard distance difference with the preset standard difference range. If the second actual-standard distance difference exceeds the preset standard difference range, control the horizontal moving platform to move horizontally according to the positive or negative value of the second actual-standard distance difference, so as to approach or move away from the first positioning sensor.

[0069] Still taking the preset standard deviation range of [-0.1mm, 0.1mm] as an example, at this time, it is necessary to calculate whether S1_Stand – 0.1 < S1_Real < S1_Stand + 0.1 is satisfied. If it is satisfied, no control adjustment is required. If it is not satisfied, it means that the distance of the square wafer in the X direction needs to be adjusted, and the adjustment is made according to the positive or negative value of the second actual-standard distance difference. Taking Figure 1 as an example, if the second actual-standard distance difference is positive, that is, the first actual coverage distance S1_Real is greater than the first standard coverage distance S1_Stand, it is considered that it is too close to the first positioning sensor 1021 at this time. The horizontal moving platform 101 can be controlled to move horizontally away from the first positioning sensor 1021; on the contrary, if the second actual-standard distance difference is negative, the horizontal moving platform 101 can be controlled to move horizontally closer to the first positioning sensor 1021.

[0070] In this way, the positioning and control of the square wafer can be completed. In addition, as Figure 3 shown, after the positioning control module controls the rotation platform 103 to rotate or controls the horizontal moving platform 101 to move horizontally, the corresponding comparison process in the current positioning step can be repeated to determine whether the rotation and movement results of the rotation platform 103 and the horizontal moving platform 101 this time are accurate.

[0071] 1. The system uses non-contact sensors for detection, avoiding direct friction and wear of components such as bearings and gears in traditional mechanical aligners, thereby reducing the maintenance frequency and replacement cost caused by component aging, and overall reducing mechanical wear and maintenance requirements.

[0072] 2. By automatically controlling the horizontal moving platform and the rotation platform for position correction, the need for manual calibration and adjustment is reduced, saving labor costs and operating costs, and reducing the production line downtime, improving production efficiency.

[0073] 3. Based on the sensor data, the actual position of the wafer is calculated in real time and precisely adjusted, reducing the alignment error caused by mechanical looseness or wear, and improving the reliability and long-term stability of the system.

[0074] 4. Multiple sensors are distributed at different positions, which can effectively adapt to the shape characteristics of the square wafer, achieve fast and accurate position positioning, and simplify the operation process.

[0075] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not exhausted. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0076] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A square wafer sensor type positioning system, characterized by, The horizontal moving platform, a plurality of positioning sensors, and a positioning control module are included. The horizontal moving platform is capable of moving in a horizontal direction, and a rotating platform is carried on the horizontal moving platform. A plurality of wafer positioning needles are arranged on the rotating platform, and the wafer positioning needles are used to carry square wafers. The plurality of positioning sensors are fixedly arranged outside the horizontal moving platform and are located at different positions on the periphery of the horizontal moving platform, and are used to detect actual coverage distances of the square wafers relative to the positioning sensors. The positioning control module determines actual positions of the square wafers according to the actual coverage distances and preset standard coverage distances, and controls the horizontal moving platform to move horizontally and / or controls the rotating platform to rotate according to the actual positions. The plurality of positioning sensors include a first positioning sensor, a second positioning sensor, and a third positioning sensor. The first positioning sensor is arranged on one side of a preset moving direction of the horizontal moving platform and faces the one side of the preset moving direction. The second positioning sensor and the third positioning sensor are respectively arranged on two sides of the preset moving direction and face the preset moving direction. The first positioning sensor is arranged in front of the second positioning sensor and the third positioning sensor along the preset moving direction. The first positioning sensor is farther away from an axis of the preset moving direction than the second positioning sensor and the third positioning sensor. The positioning control module acquires first actual coverage distances, second actual coverage distances, and third actual coverage distances respectively corresponding to the first positioning sensor, the second positioning sensor, and the third positioning sensor, and first standard coverage distances, second standard coverage distances, and third standard coverage distances respectively corresponding to the first positioning sensor, the second positioning sensor, and the third positioning sensor. A distance difference between the second actual coverage distance and the third actual coverage distance is compared with a distance difference between the second standard coverage distance and the third standard coverage distance, so as to control the rotating platform to rotate according to a comparison result and a preset standard difference range. A distance difference between an actual coverage distance corresponding to the second positioning sensor or the third positioning sensor and a standard coverage distance corresponding to the second positioning sensor or the third positioning sensor is determined, and the distance difference is compared with a preset standard difference range, so as to control the horizontal moving platform to move horizontally according to a comparison result. A distance difference between the first actual coverage distance and the first standard coverage distance is determined, and the distance difference is compared with a preset standard difference range, so as to control the rotating platform to rotate according to a comparison result. The positioning control module determines a first actual distance difference between the second actual coverage distance and the third actual coverage distance, and a first standard distance difference between the second standard coverage distance and the third standard coverage distance. If a difference between an absolute value of the first actual distance difference value and an absolute value of the first standard distance difference value exceeds the preset standard difference value range, a corresponding rotating direction is selected according to a positive or negative value of the first actual distance difference value, and the rotating platform is controlled to rotate. The positioning control module determines a first actual-standard distance difference value between a corresponding actual coverage distance and a corresponding standard coverage distance of the second positioning sensor or the third positioning sensor. The first actual-standard distance difference value is compared with a preset standard difference value range, and if the first actual-standard distance difference value exceeds the preset standard difference value range, the horizontal moving platform is controlled to move horizontally to approach or move away from the positioning sensor used for calculating the first actual-standard distance difference value according to a positive or negative value of the first actual-standard distance difference value. The positioning control module determines a second actual-standard distance difference value between the first actual coverage distance and the first standard coverage distance. The second actual-standard distance difference value is compared with a preset standard difference value range, and if the second actual-standard distance difference value exceeds the preset standard difference value range, the horizontal moving platform is controlled to move horizontally to approach or move away from the first positioning sensor according to a positive or negative value of the second actual-standard distance difference value.

2. The system of claim 1, wherein, The preset standard difference value range ranges from -0.1 mm to 0.1 mm.

3. The system of claim 1, wherein, After the rotating platform is controlled to rotate or the horizontal moving platform is controlled to move horizontally, the positioning control module repeats the comparison process of the current positioning step.

4. The system of claim 1, wherein, Before receiving the actual coverage distance sent by the positioning sensor, the positioning control module determines that the horizontal moving platform has reached a preset zero position and carries a new square wafer to a preset working position corresponding to the positioning control module.

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