Positioning device for wafer

Abstract

The positioning device comprises a disc body, the edge of the surface of the disc body is provided with a step which is formed in a protruding mode and used for supporting the edge of the wafer, a groove is formed in the position, located on the inner side of the step, of the surface of the disc body, an air inlet hole is formed in the center of the bottom face of the groove, and a negative pressure annular groove surrounding the air inlet hole is formed in the position close to the step. The air inlet hole is used for inputting air into the groove to form an air film so as to enable the wafer to be in an air floating state, and the negative pressure ring groove is configured to be suitable for providing a negative pressure environment so as to enhance the air tightness between the edge of the wafer and the step; the clamping parts are arranged on the step at intervals in the circumferential direction, the clamping parts are configured to be heating expansion bodies, the clamping parts clamp the wafer after being heated and expanded, and the clamping force is suitable for providing friction force for the wafer in the high-speed rotating state of the disc body so that the wafer can synchronously rotate along with the disc body. The method has the beneficial effects that the damage to the wafer is reduced, and particles generated in a detection environment are reduced.

Description

Technical Field

[0001] This invention relates to a positioning device for wafers, belonging to the technical field of precision semiconductor equipment. Background Technology

[0002] In the wafer fabrication process, a positioning device is needed to clamp and position the wafer to ensure stability and accuracy during testing, thus meeting testing requirements. Existing positioning devices position the wafer and then rotate it at high speed synchronously for monitoring. During positioning, the bottom surface of the wafer directly contacts the positioning device's disk, and clamping components are then used to hold the wafer at its edge. This direct contact between the disk and the wafer can cause surface damage. Furthermore, sufficient pressure needs to be applied by the clamping components against the wafer edge to generate enough friction to maintain synchronous high-speed rotation. Therefore, the clamping method and the direct contact between the disk and the wafer can lead to significant chip loss, which is detrimental to wafer testing. Summary of the Invention

[0003] The purpose of this invention is to provide a positioning device for wafers that reduces damage to wafers and reduces particles generated in the inspection environment.

[0004] The present invention is achieved through the following technical solution.

[0005] A positioning device for a wafer, comprising:

[0006] The disk body has raised edges on its surface to form steps for supporting the wafer edge. A groove is formed on the surface of the disk body inside the steps. An air inlet is provided at the center of the bottom surface of the groove, and a negative pressure ring groove is provided near the steps to surround the air inlet. The air inlet is used to input gas into the groove to form an air film so that the wafer is in an air-floating state. The negative pressure ring groove is configured to provide a negative pressure environment to enhance the airtightness between the wafer edge and the steps.

[0007] Multiple clamping components are arranged circumferentially on the steps. The clamping components are configured as thermally expandable bodies, and after thermal expansion, the multiple clamping components clamp the wafer. The clamping force is suitable for providing friction to the wafer under high-speed rotation of the disk so that it rotates synchronously with the disk.

[0008] As a further improvement to the present invention, it also includes:

[0009] Multiple lifting rods are arranged circumferentially on the steps. The vertical lifting of the lifting rods is used to receive the wafer during the process of moving the wafer to the disk for positioning, and to lift and remove the wafer positioned on the disk after the test is completed. The vertical lowering of the lifting rods is used for the step to receive the wafer after it has been received.

[0010] As a further improvement of the present invention, the top surface of the lifting rod has an adjustment column formed by a vertical protrusion. The adjustment column has a sliding adjustment part facing the edge of the wafer. This is suitable for the lifting rod to support the wafer and for the wafer to be offset in the horizontal direction. Under its own weight, the edge of the wafer can slide along the sliding adjustment part to the top surface of the lifting rod and correct its position in the horizontal direction relative to the disk.

[0011] As a further improvement to the present invention, it also includes:

[0012] Multiple limiting components are arranged circumferentially on the step. Each limiting component includes a rotating arm rotatably mounted on the step, a limiting head mounted on the rotating arm, and an elastic element for driving the rotating arm to a reset state. When the elastic element has elastic potential energy, the positioning head separates from the wafer positioned on the disk. When the rotating arm is in the reset state, the limiting head contacts the top edge of the wafer positioned on the disk, which is used to maintain the stability of the wafer's air-floating state when the disk and the wafer are rotating synchronously at high speed.

[0013] As a further improvement of the present invention, the limiting component also includes a housing and a pushing member. The rotating arm, the elastic member and the pushing member are all disposed in the housing. The housing has an opening that allows the portion of the rotating arm with the limiting head to extend out. One end of the elastic member is supported on the inner wall of the housing, and the other end supports the pushing member. The pushing member contacts the rotating arm and is used to push the rotating arm to rotate.

[0014] As a further improvement of the present invention, the portion of the limiting head that contacts the wafer is spherical.

[0015] As a further improvement of the present invention, the bottom surface of the groove has a raised inner sealing dam that is circumferentially closed, located inside the negative pressure annular groove. This divides the space between the wafer bottom surface and the groove into an air flotation zone located inside the inner sealing dam and a negative pressure zone located between the step sidewall and the inner sealing dam. An inner flow-limiting air resistance channel is formed between the inner sealing dam and the wafer bottom surface to increase the flow resistance from the air flotation zone to the negative pressure zone.

[0016] As a further improvement of the present invention, the bottom surface of the groove is located outside the negative pressure ring groove and has a raised and circumferentially closed outer sealing dam. An outer flow-limiting gas barrier channel is formed between the outer sealing dam and the bottom surface of the wafer to prevent external atmosphere from flowing back into the negative pressure ring groove from the edge of the wafer and the step.

[0017] As a further improvement of the present invention, the clamping component includes a base disposed on a step, an active heating layer disposed on the base, and a heat-conducting layer disposed on the active heating layer and heated and expanded thereon to clamp the edge of the wafer.

[0018] The beneficial effects of this invention are:

[0019] The air inlet design avoids scratches, wear, or contamination that could occur from direct contact between the disk surface and the wafer bottom surface, greatly protecting the wafer surface integrity. This is particularly suitable for processing ultra-precision and fragile wafers. On the other hand, the uniform support of the gas film also reduces wafer deformation, providing a flatter reference plane for high-precision inspection. The negative pressure ring groove effectively blocks the path of gas leakage from the edge, thereby maintaining stable gas film pressure. Especially when the disk rotates at high speed, the centrifugal effect and airflow disturbance caused by the rotation can disrupt the dynamic stability of the gas film, potentially leading to uneven gas film pressure distribution or thickness variations. The additional constraint force provided by the negative pressure adsorption firmly holds the wafer edge, effectively suppressing possible radial drift, floating, or vibration, ensuring positioning accuracy under high-speed conditions. The clamping components are designed to avoid any contact and pressure on the wafer's functional areas, i.e., the top surface, eliminating the risk of microcracks, stress, or mechanical damage to the wafer surface caused by contact pressure. The clamping force required for lateral clamping is only sufficient to provide enough lateral friction to resist the tangential force during rotation. Generally, less force is required, and the optimizable design of the contact area and method can greatly reduce particulate matter generated by friction, significantly improving the cleanliness of the inspection environment and meeting the stringent requirements of particle control in high-end processes. The advantage of setting the clamping components as thermally expandable bodies, i.e., small stroke, is also suitable for applications in narrow spaces at steps. Attached Figure Description

[0020] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings to aid in understanding the objectives and advantages of the present invention, wherein:

[0021] Figure 1 This is a schematic diagram of the positioning device.

[0022] Figure 2 A partial sectional view of the positioning device and the lifting rod used to complete the positioning process;

[0023] Figure 3 This is a partial cross-sectional view of the positioning device regarding the limiting component.

[0024] Figure 4 This is a partial cross-sectional view of the positioning device regarding the clamping component;

[0025] Figure 5 This is a partial cross-sectional schematic diagram of the positioning device regarding the negative pressure annular groove, the inner sealing dam, and the outer sealing dam. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0027] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the construction shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0028] This embodiment illustrates a positioning device for a wafer, referring to... Figures 1-5 The device includes a disk body 1 and multiple clamping components 2. The edge of the disk body 1 has a raised step 11 for supporting the edge of the wafer 5. The edge of the wafer 5 is typically supported by a 1.5-2.0 mm wide portion. The inner side of the step 11 forms a groove 12 with a flat bottom surface on the surface of the disk body 1, ensuring that a uniform gap is formed between the bottom surface of the groove 12 and the bottom surface of the wafer 5. An air inlet 1a is provided at the center of the bottom surface of the groove 12 for introducing gas into the groove 12 to form an air film under the wafer 5, so that the wafer 5 is in a stable non-contact air-floating state. This avoids scratches, wear or contamination that may be caused by direct contact between the surface of the disk body 1 and the bottom surface of the wafer 5, greatly protecting the surface integrity of the wafer 5, and is particularly suitable for the processing of ultra-precision and fragile wafers 5. On the other hand, the uniform support of the air film can also reduce the deformation of the wafer 5, providing a flatter reference plane for high-precision inspection.

[0029] The bottom surface of the groove 12, near the step 11, is provided with a negative pressure ring groove 1b surrounding the air inlet 1a. Its bottom is connected to a negative pressure extraction channel 1c extending outside the disk body 1, which is connected to an external negative pressure extraction device. The negative pressure ring groove 1b generates a negative pressure environment in the area below the edge of the corresponding wafer 5, producing a downward adsorption force that enhances the airtightness between the edge of the wafer 5 and the step 11, effectively blocking the path of gas leakage from the edge, thereby maintaining stable gas film pressure. Especially when the disk body 1 rotates at high speed, the centrifugal effect and airflow disturbance caused by the rotation can disrupt the dynamic stability of the gas film, potentially leading to uneven gas film pressure distribution or thickness changes. The additional constraint force provided by the negative pressure adsorption firmly holds the edge of the wafer 5, effectively suppressing possible radial drift, floating, or vibration, ensuring positioning accuracy under high-speed operating conditions.

[0030] Multiple clamping components 2 are arranged circumferentially on the step 11. The clamping components 2 are configured as thermally expandable bodies; after being heated and expanding, they clamp the edge of the wafer 5 from its circumferential side. This side-clamping method differs from the existing method of pressing the wafer 5 from above. Firstly, it avoids any contact and pressure on the functional area of ​​the wafer 5, i.e., its top surface, eliminating the risk of microcracks, stress, or mechanical damage to the wafer 5 surface due to contact pressure. This is crucial for increasingly thin and fragile advanced process wafers 5. Secondly, when maintaining the wafer 5 and disk 1 at high speed and synchronous rotation, traditional top clamping requires sufficient pressure to obtain sufficient static friction, easily generating debris or particulate contamination at the clamping point. In contrast, the side-clamping method of this solution only requires sufficient clamping force to provide enough lateral friction to resist the tangential force during rotation. Typically, less force is required, and the optimizable design of the contact area and method can significantly reduce particulate matter generated by friction. Improving the cleanliness of the testing environment meets the stringent requirements of high-end processes for particle control. Furthermore, since the action site is the edge of wafer 5, rather than the functional area of ​​wafer 5 (i.e., the top surface), damage to wafer 5 is further reduced. In addition, thermal expansion is chosen as the driving mechanism. Compared with mechanically driven clamping methods, its structure is simpler and more compact, with no complex moving parts, resulting in high reliability and less particle generation. Thermal expansion can provide a very uniform and controllable clamping force. The clamping force can be finely adjusted by precisely controlling the temperature, with fast response speed and high control accuracy, making it very suitable for wafer 5 as the clamping object. Moreover, the limited space at step 11 of disk 1 is not conducive to mechanically driven solutions with relatively large strokes. Setting the clamping component 2 as a thermally expanding body, with its advantage of small stroke, is also suitable for this application scenario.

[0031] In this embodiment, considering the automation and reliability of the wafer 5 transfer and positioning process, the positioning device also includes multiple lifting rods 3 arranged circumferentially on the steps 11. These lifting rods 3 can be vertically raised and lowered by a driver located below the disk body 1. During the wafer 5 transfer process, the lifting rods 3 first rise to a position where their top surface is higher than the steps 11 of the disk body 1. At this point, the EFEM or a dedicated robot arm transfers the wafer 5 and places it on the top surface of the raised lifting rods 3, completing the initial receiving. Subsequently, the lifting rods 3 descend, smoothly transferring the wafer 5 to the final support and positioning by the steps 11 of the disk body 1. After the inspection is completed, the clamping component 2 stops heating and shrinks to release the clamp on the wafer 5. The lifting rods 3 rise again, pushing the wafer 5 off the steps 11, freeing it from any clamping or adsorption, so that the robot arm can remove it. The arrangement of the lifting rods 3 makes the wafer 5 loading and unloading process smooth and precise. The lifting rods 3, as an intermediate transition carrier, improve the safety and reliability of the operation.

[0032] In this embodiment, in order to further improve the centering accuracy and positioning success rate of the wafer 5 during initial placement, the top surface of the lifting rod 3 has a vertically protruding adjustment column 31. The adjustment column 31 is usually set as a tapered column structure with a diameter that gradually decreases from bottom to top. Its side forms a sliding adjustment part facing the edge of the wafer 5. When the EFEM or robot places the wafer 5 on the raised lifting rod 3, if the wafer 5 is offset in the horizontal direction, the edge of the wafer 5 will first contact the sliding adjustment part of the adjustment column 31, i.e., the tapered inclined surface. Under the action of the component force of the wafer 5's own gravity, its edge will naturally slide down along this sliding adjustment part until it is stably placed on the top surface of the lifting rod 3, thereby automatically correcting its horizontal position deviation. This self-alignment mechanism is crucial because if the center of wafer 5 deviates from the center of disk 1 when it is finally supported on step 11, it will first cause uneven contact between the edge of wafer 5 and step 11, potentially leading to excessive local gaps and gas leakage, damaging the uniformity and stability of the air flotation film, and even causing wafer 5 to tilt. Secondly, it will also cause inconsistent contact and clamping force between the various clamping components 2 and the edge of wafer 5, which not only affects rotational synchronization but may also introduce unnecessary stress. The lifting rod 3 and the adjusting column 31 are typically manufactured using polyetheretherketone (PEEK) in a single molding process. This material has a moderate surface resistivity of 10^6-10^8 Ω, which effectively prevents static electricity accumulation. Its coefficient of friction is low, approximately 0.25 for silicon, ensuring smooth sliding adjustment of wafer 5 while greatly reducing friction and wear during the sliding process, generating almost no particulate matter, perfectly meeting the stringent cleanliness requirements of semiconductor processes.

[0033] In this embodiment, considering the extreme stability of the air-float state under ultra-high-speed rotation conditions, the positioning device further includes multiple limiting components 4 arranged circumferentially on the step 11. Each limiting component 4 includes a rotating arm 41 rotatably mounted on the step 11, a limiting head 42 mounted on the top of the rotating arm 41, and an elastic element 43 for driving the rotating arm 41 to rotate to a reset state where its limiting head 42 contacts the wafer 5. When loading or unloading the wafer 5, a driver outside the disk 1 acts on the rotating arm 41, typically on the top of the rotating arm 41. This force overcomes the elastic force, causing the rotating arm 41 to rotate to a separated state where the limiting head 42 is away from the wafer 5. When loading or unloading is complete, the driver is driven again to bring the limiting head 42 into contact with the wafer 5. At this time, the elastic potential energy of the elastic element 43 is released, maintaining the reset state of the rotating arm 41. It is important to note that the negative pressure adsorption force provided by the negative pressure annular groove 1b should not be too strong. This is because the gas film generates an upward buoyancy force on the central region of wafer 5, while the negative pressure generates a downward suction force on the edge. The two are in opposite directions. If the negative pressure is too strong, it will cause excessive static displacement, i.e., deformation, such as a "bowl-shaped" depression, which will seriously affect the accuracy of the detection. However, when the disk 1 rotates at ultra-high speed, the gas film itself may become unstable due to centrifugal force, turbulence, etc. There is still a slight risk of leakage between the edge of wafer 5 and step 11, which may cause wafer 5 to have a slight tendency to float upward. At this time, the slight contact between the limiting head 42 and the top surface of the wafer 5 is not to provide frictional force to drive rotation, but merely to act as a physical limit, providing a very small constraint force to effectively prevent any tendency of the wafer 5 to float at high speed, thus perfectly avoiding the vicious cycle of sealing failure and further air leakage caused by floating, ensuring the air-floating state is foolproof under extreme working conditions. This light-touch limiting method is fundamentally different from the method in the prior art that relies on clamping and pressing to provide huge frictional force.

[0034] In this embodiment, to reduce potential particulate contamination from the limiting component 4, the limiting component 4 also includes a housing 45 and a pushing component 44. A portion of the rotating arm 41, the elastic element 43, and the pushing component 44 are all housed within the housing 45. The housing 45 has an opening at an appropriate location to allow the portion of the rotating arm 41 with the limiting head 42 to extend out. One end of the elastic element 43 is supported on the inner wall of the housing 45, while the other end supports the pushing component 44, which then contacts the rotating arm 41 to transmit elastic force. This design, which completely encloses the kinematic pair and elastic element, completely isolates metal debris and particulate matter that may be generated by friction or impact during the rotation of the rotating arm 41, the sliding of the pushing component 44, and the deformation of the elastic element 43 within the housing 45. This effectively prevents these contaminants from escaping into the cleanroom environment where the wafer 5 is located, fundamentally resolving the contradiction between wear of moving parts and cleanliness requirements.

[0035] In this embodiment, the contact interface between the limiting head 42 and the wafer 5 has been optimized, with the contact area between the limiting head 42 and the wafer 5 designed as a spherical shape. Spherical contact minimizes the possible contact area and maintains point contact regardless of changes in the contact angle, significantly reducing potential localized pressure and frictional stress on the wafer 5 surface. During high-speed rotation, this low-contact-area spherical design also effectively reduces sliding friction, thereby minimizing particulate matter and damage caused by contact. The limiting head 42 is typically made of the same polyetheretherketone (PEEK) material as the lifting rod 3 to ensure excellent performance.

[0036] In this embodiment, to enhance the stability of the negative pressure zone r2, an inner sealing dam 121, which is formed by a protrusion and is circumferentially closed, is provided on the bottom surface of the groove 12, inside the negative pressure annular groove 1b. The inner sealing dam 121 divides the space between the bottom surface of the wafer 5 and the bottom surface of the groove 12 into two regions: an air flotation zone r1 located inside the inner sealing dam 121, and a negative pressure zone r2 located between the side wall of the step 11 and the inner sealing dam 121. A very small gap is maintained between the top of the inner sealing dam 121 and the bottom surface of the wafer 5, forming a narrow inner flow-limiting air resistance channel d1. The inner flow-limiting air resistance channel d1 generates extremely high flow resistance to the gas flowing from the central air flotation zone r1 to the surrounding negative pressure zone r2, which greatly limits the flow rate of gas leaking into the negative pressure ring groove 1b. This allows the negative pressure extraction device to establish and maintain a stronger and more stable negative pressure environment in the negative pressure ring groove 1b with higher efficiency, thereby achieving a stronger edge adsorption sealing effect with less extraction power consumption. Therefore, the negative pressure extraction device can be selected as a small-power model as possible, which is beneficial for its relatively narrow installation space below the disc body 1.

[0037] In this embodiment, to isolate external atmospheric interference and further improve the stability of the negative pressure zone r2, a raised, circumferentially closed outer sealing dam 122 is provided on the bottom surface of the groove 12, outside the negative pressure annular groove 1b. A narrow outer flow-limiting air resistance channel d2 is also formed between the top of the outer sealing dam 122 and the bottom surface of the wafer 5. The function of the outer flow-limiting air resistance channel d2 is to greatly increase the flow resistance of external ambient air flowing back into the negative pressure annular groove 1b from the gap between the edge of the wafer 5 and the step 11. Like a barrier, it effectively blocks external air pressure fluctuations from interfering with the negative pressure environment inside the negative pressure annular groove 1b, ensuring the reliability and stability of the negative pressure adsorption effect.

[0038] In this embodiment, the clamping component 2 includes a base 21 disposed on the step 11. The base 21 is preferably made of a thermally insulating material with poor thermal conductivity, such as alumina, to prevent heat from diffusing into the disk 1. An active heating layer 22 is disposed on the base 21. This layer can house a micro-thick-film heating circuit precisely fabricated through an etching process, operating on a principle similar to an electric blanket. This offers advantages such as rapid heating and cooling, low thermal inertia, high temperature control accuracy, and long lifespan. A heat-conducting layer 23 is disposed on the active heating layer 22. The heat-conducting layer 23 is made of a high thermal conductivity material such as oxygen-free copper alloy, ensuring that heat can be quickly and evenly transferred to the entire contact surface between the active heating layer 22 and the edge of the wafer 5, thereby providing a uniform clamping force. Furthermore, a thin-film piezoresistive sensor can be embedded in the active heating layer 22 to monitor the pressure on the clamping surface in real time, providing feedback signals for closed-loop precise control of the clamping force, ensuring that the clamping process is both safe and reliable without overload.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A positioning device for a wafer (5), characterized in that, include: The disk body (1) has a raised edge on the surface of the disk body (1) to support the edge of the wafer (5) and a step (11) is formed on the surface of the disk body (1) inside the step (11). The bottom surface of the groove (12) is flat to ensure that the gap width between the bottom surface of the groove (12) and the bottom surface of the wafer (5) is uniform. An air inlet (1a) is provided at the center of the bottom surface of the groove (12), and a negative pressure ring groove (1b) is provided near the step (11) to surround the air inlet (1a). The air inlet (1a) is used to input gas into the groove (12) to form an air film so that the wafer (5) is in an air-floating state. The negative pressure ring groove (1b) is configured to provide a negative pressure environment to enhance the airtightness between the edge of the wafer (5) and the step (11). Multiple clamping components (2) are arranged circumferentially on the step (11). The clamping components (2) are configured as thermally expandable bodies. After thermal expansion, the multiple clamping components (2) clamp the wafer (5). The clamping force is suitable for providing friction to the wafer (5) in the high-speed rotation state of the disk (1) so that it rotates synchronously with the disk (1).

2. The positioning device according to claim 1, characterized in that, Also includes: Multiple lifting rods (3) are arranged circumferentially on the step (11). The vertical lifting of the lifting rods (3) is used to receive the wafer (5) during the process of moving the wafer (5) to the disk (1) for positioning, and to lift and remove the wafer (5) positioned on the disk (1) after the test is completed. The vertical lowering of the lifting rods (3) is used for receiving the wafer (5) and then being received by the step (11).

3. The positioning device according to claim 1, characterized in that, The top surface of the lifting rod (3) has a vertically protruding adjustment column (31), which has a sliding adjustment part facing the edge of the wafer (5). This is suitable for the lifting rod (3) to support the wafer (5) and for the wafer (5) to slide along the sliding adjustment part to the top surface of the lifting rod (3) and correct its position relative to the disk (1) in the horizontal direction when the wafer (5) is offset in the horizontal direction.

4. The positioning device according to claim 1, characterized in that, Also includes: Multiple limiting components (4) are arranged circumferentially on the step (11). Each limiting component (4) includes a rotating arm (41) rotatably mounted on the step (11), a limiting head (42) mounted on the rotating arm (41), and an elastic element (43) for driving the rotating arm (41) to rotate to a reset state. When the elastic element (43) has elastic potential energy, the positioning head and the wafer (5) positioned on the disk (1) are separated. When the rotating arm (41) is in the reset state, the limiting head (42) and the top edge of the wafer (5) positioned on the disk (1) are in contact, which is used to maintain the stability of the wafer (5) in the air-floating state when the disk (1) and the wafer (5) are rotating synchronously at high speed.

5. The positioning device according to claim 1, characterized in that, The limiting component (4) also includes a housing (45) and a pusher (44). The rotating arm (41), the elastic member (43), and the pusher (44) are all disposed inside the housing (45). The housing (45) has an opening that allows the rotating arm (41) to extend part of the limiting head (42). One end of the elastic member (43) is supported on the inner wall of the housing (45), and the other end supports the pusher (44). The pusher (44) contacts the rotating arm (41) and is used to push the rotating arm (41) to rotate.

6. The positioning device according to claim 1, characterized in that, The portion of the limiting head (42) that contacts the wafer (5) is spherical.

7. The positioning device according to claim 1, characterized in that, The bottom surface of the groove (12) is located inside the negative pressure ring groove (1b) and has a raised inner sealing dam (121) that is closed in a ring direction. This makes the space between the bottom surface of the wafer (5) and the groove (12) divided into an air flotation area (r1) located inside the inner sealing dam (121) and a negative pressure area (r2) located between the side wall of the step (11) and the inner sealing dam (121). An inner flow-limiting air resistance channel (d1) is formed between the inner sealing dam (121) and the bottom surface of the wafer (5) to increase the flow resistance from the air flotation area (r1) to the negative pressure area (r2).

8. The positioning device according to claim 1, characterized in that, The bottom surface of the groove (12) is located outside the negative pressure ring groove (1b) and has a raised outer sealing dam (122) that is closed in a ring. An outer flow-limiting gas barrier channel (d2) is formed between the outer sealing dam (122) and the bottom surface of the wafer (5) to block the external atmosphere from flowing back into the negative pressure ring groove (1b) between the edge of the wafer (5) and the step (11).

9. The positioning device according to claim 1, characterized in that, The clamping component (2) includes a base (21) disposed on the step (11), an active heating layer (22) disposed on the base (21), and a heat-conducting layer (23) disposed on the active heating layer (22) and heated and expanded thereon to clamp the edge of the wafer (5).

Images