Wafer clamping mechanism and wafer cleaning spin-drying method

Abstract

The application discloses a wafer clamping mechanism and a wafer cleaning and spin-drying method. The wafer clamping mechanism comprises a chuck, a base capable of rotating relative to the chuck around a center axis of the base, a supporting part provided on the base and having a supporting surface capable of contacting a bottom surface of a wafer, a plurality of supporting parts of the base being used for horizontally or horizontally supporting the wafer, and a clamping part provided on the base and having a first clamping surface capable of contacting a side surface of the wafer. The base has a supporting position and a clamping position. When the base is in the supporting position, the supporting surface contacts the bottom surface of the wafer, and the first clamping surface does not contact the wafer. When the base is switched from the supporting position to the clamping position relative to the chuck, the contact position between the supporting surface and the bottom surface of the wafer gradually approaches a direction of a center of the wafer until the first clamping surface of the clamping part contacts the side surface of the wafer to clamp the wafer, and the wafer is separated from the supporting surface. The wafer can be stably and reliably clamped in a full rotation speed range without depending on a rotation speed or a centrifugal force effect.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor integrated circuit chip manufacturing technology, and in particular relates to a wafer clamping mechanism and a wafer cleaning and drying method. Background Technology

[0002] With the continuous advancement of semiconductor manufacturing technology, the importance of ultra-clean processes is constantly increasing. The requirements for the cleanliness of wafer surfaces after cleaning and drying are also continuously rising in chemical mechanical planarization (CMP) equipment.

[0003] In chemical mechanical planarization (CMP) equipment, after the wafer cleaning process, a final cleaning and drying process is required. Specifically, the wet wafer is fixed on a chuck, and the chuck rotates the wafer, using centrifugal force to dry it. During this process, it is crucial not only to ensure the wafer remains firmly fixed on the chuck during high-speed rotation but also to ensure that the liquid distributed on the wafer surface can be discharged unimpeded under centrifugal force. Otherwise, liquid residue on the wafer surface will affect the process results. In particular, the wafer-bearing surface of the chuck, which is in direct contact with the back of the wafer, is more prone to liquid accumulation.

[0004] Chinese patent CN118943073B discloses a "Wafer Chuck and Semiconductor Equipment," which has the following technical features: A. The switching between the release and clamping positions requires the synchronous movement of a lifting mechanism and a rotating mechanism. The lifting mechanism rises to limit the chuck, and the rotating drive mechanism moves to create an angle difference between the chuck and the housing, thereby allowing the jaws to rotate and achieve the limiting position; B. When the wafer is in the release and clamping positions, the platform supporting the wafer is always in contact with the wafer; C. The drive component in this patent serves as both the power source for wafer rotation and the power source for switching between the clamping and release positions. Its structure is relatively complex.

[0005] Chinese patent CN119803007A discloses a "Wafer Rotary Drying Mechanism," which reveals that during the centrifugal rotary drying process, water droplets and stains easily remain at and near the contact point between the back of the wafer and the support surface, forming a high-pressure capillary area. This leads to the problem that the accumulated liquid in this area cannot be spun out and is difficult to remove during the wafer spin-drying process. The solution is to install a centrifugal drainage tank between the support surface and the clamping surface. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a wafer clamping mechanism and a wafer cleaning and spin-drying method. The mechanism has a simple structure, provides stable clamping, and achieves excellent wafer cleaning results. It solves the problem in the prior art where the bearing surface comes into contact with the bottom surface of the wafer during the spin-drying process, and the liquid cannot be discharged smoothly at the contact point, resulting in liquid residue.

[0007] The technical scheme adopted by the present application to solve its technical problems is: a wafer clamping mechanism, comprising,

[0008] a chuck;

[0009] a plurality of bases, which are circumferentially spaced apart along the chuck and can rotate relative to the chuck about their own central axes;

[0010] a supporting portion provided on the base and having a bearing surface that can contact the bottom surface of the wafer, and the supporting portions of the plurality of bases cooperate to support the wafer horizontally or nearly horizontally;

[0011] a clamping portion provided on the base and having a first clamping surface that can contact the side surface of the wafer;

[0012] The base has a supporting position and a clamping position. When in the supporting position, the bearing surface contacts the bottom surface of the wafer, and the first clamping surface does not contact the wafer. When the base is switched from the supporting position to the clamping position relative to the chuck, the contact position of the bearing surface with the bottom surface of the wafer gradually approaches the direction of the center of the wafer, until the first clamping surfaces of the plurality of clamping portions abut the side surface of the wafer to clamp the wafer, and the wafer is separated from the bearing surface.

[0013] Further, the inclination angle of the bearing surface relative to the horizontal plane is 0-15°; or, the inclination angle of the bearing surface relative to the horizontal plane is 3-15°.

[0014] Further, the first clamping surface is vertically arranged, and the clamping portion further comprises a second clamping surface at an angle with the first clamping surface, and the inclination angle of the second clamping surface relative to the horizontal plane is 30-70°.

[0015] Further, the thickness of the wafer is S, the height of the intersection of the first clamping surface and the second clamping surface is H1, the height of the bottom surface of the wafer when in the supporting position is H2, and the height of the contact point between the bottom surface of the wafer and the bearing surface when the wafer is separated from the bearing surface is H3, the absolute value of the difference between H1 and H2 is less than or equal to 0.5S, the absolute value of the difference between H3 and H2 is less than or equal to 1.5S, and the absolute value of the difference between H3 and H2 is greater than the absolute value of the difference between H1 and H2.

[0016] Further, the number of bases is six, which are uniformly distributed along the circumference of the chuck; and a driving unit is connected to the bottom of the base.

[0017] Further, the supporting portion and the clamping portion are arranged on the two radial sides of the base.

[0018] Further, the base further has an over-clamping position, and the base rotates in the same direction to sequentially switch from the supporting position to the clamping position and the over-clamping position.

[0019] Further, the supporting part is in a column shape, and the outer wall is vertically protruded to form a bearing part, the bearing surface is located on the top surface of the bearing part, and the supporting part further forms a guide surface located above the bearing surface.

[0020] The application further discloses a wafer cleaning and drying method, which is performed by the wafer clamping mechanism and comprises the following steps.

[0021] The chuck is stationary, and the base is rotated relative to the chuck to the receiving position.

[0022] The transfer device horizontally or nearly horizontally places the wafer on the bearing surfaces of the base supporting parts, and the clamping parts do not contact the wafer at this time.

[0023] The plurality of bases are rotated relative to the chuck respectively, the clamping parts are close to the wafer, the side surface of the wafer slides against the second clamping surface, the contact position between the bottom surface of the wafer and the bearing surface gradually approaches the center of the wafer, until the first clamping surface abuts against the side surface of the wafer, and the wafer is separated from the bearing surface.

[0024] The wafer is stably clamped by the plurality of clamping parts, and the chuck is rotated at a high speed to realize the drying of the wafer.

[0025] The chuck stops rotating, and the transfer device takes away the wafer after drying.

[0026] Further, the following steps are further included before the wafer is placed on the bearing surface by the transfer device.

[0027] The base is switched from the receiving position to the clamping position to determine whether the wafer clamping mechanism has placed the wafer, and if not, the base is reversely rotated relative to the chuck to the receiving position.

[0028] Further, the process that the transfer device horizontally or nearly horizontally places the wafer on the bearing surfaces of the plurality of base supporting parts comprises the following sub-steps.

[0029] The transfer device sucks the wafer from the last station and moves horizontally above the chuck, and the center of the wafer is coincident or nearly coincident with the center of the chuck.

[0030] The transfer device is located below the wafer and vertically descends with the wafer until the bottom surface of the wafer contacts the bearing surface.

[0031] The transfer device continues to descend by 5-8 mm, and the transfer device after being separated from the wafer moves horizontally away from below the wafer.

[0032] The beneficial effects of the present application are: 1) compared with the prior art which relies on centrifugal force to achieve passive clamping of the wafer, only when the rotation speed reaches a certain threshold can sufficient clamping force be provided, and in the rotation start-stop stage, the clamping force is easily attenuated due to insufficient rotation speed, which easily causes wafer displacement or even surface damage, the present application actively achieves self-rotation of the base before starting rotation, and uses the clamping part to achieve stable clamping of the wafer, and the clamping force is applied to the wafer by driving the base to rotate through an independent driving unit, and after clamping is completed, the wafer is spun dry at high speed, which does not rely on rotation speed or centrifugal force effect, and can achieve stable and reliable clamping of the wafer in the whole rotation speed range, including the centrifugal force insufficient working condition such as start and deceleration, thereby fundamentally avoiding the risk of wafer surface scratching or even wafer dropping caused by clamping force fluctuation; 2) there is a contradiction in the prior art: in order to reduce the requirement for wafer placement accuracy, the support surface needs to have a larger size and a smaller horizontal inclination angle, and in order to achieve better process effect and suppress capillary effect, the support surface needs to have a smaller size and a larger inclination angle; these two mutually restrictive requirements are difficult to be optimized simultaneously in a single jaw structure, the clamping mechanism proposed in the present application separates the clamping surface and the bearing surface on both sides of the base, achieving functional separation: one side is responsible for supporting, and the other side is responsible for clamping, this layout decouples the two types of functional requirements, ensuring the tolerance capability of wafer placement, and effectively suppressing the capillary effect, thereby balancing process performance and operation reliability; 3) the rotation of the base is used to switch the wafer receiving position and the clamping position, and through the independent arrangement of the bearing surface and the first clamping surface, the bearing surface and the wafer can be separated when the base rotates by a small angle (generally 3-10°) in the clamping position, so that the liquid on the top and bottom surfaces of the wafer can be discharged under the action of centrifugal force without obstruction; 4) in integrated circuit manufacturing process, silicon wafer or wafer as a typical disc-shaped substrate needs to go through etching, cleaning and detection and other precise processes, in such process links, the wafer needs to be reliably fixed and supported by a special clamping device, the core requirement of which is to provide sufficient mechanical constraint stability and strictly avoid physical contact with the upper and lower process surfaces of the wafer to prevent the introduction of pollution or damage and ensure the electrical performance and yield of the device, the clamping mechanism proposed in the present application has process compatibility and operation functionality: on the one hand, it can support the wafer when interacting with upstream and downstream equipment, and on the other hand, it can apply stable clamping during processing, thereby balancing the positioning accuracy, process safety and surface integrity of the wafer in the complete process; 5) the clamping wafer has good consistency and is suitable for clamping wafers of different sizes; 6) the rotation angle of the base can be used to determine whether the clamping mechanism has a wafer or whether the wafer placement state is normal, when there is no wafer on the clamping mechanism, the rotation angle is greater than the angle when clamping the wafer normally, at this time the base is in an over-clamping position, and it can be judged that there is no wafer on the clamping device or the wafer is in a dropped or inclined state. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 A perspective view of the wafer clamping mechanism and wafer cooperation provided by the present application.

[0034] Figure 2 A perspective view of the wafer clamping mechanism provided by the present application.

[0035] Figure 3 A perspective view of the base provided by the present application.

[0036] Figure 4 A front view of the base provided by the present application.

[0037] Figure 5 A schematic view of the structure of the part where the bearing surface is located.

[0038] Figure 6 A top view of the base and wafer cooperation provided by the present application. Figure 1 At this time, it is in the receiving position.

[0039] Figure 7 A top view of the base and wafer cooperation provided by the present application. Figure 2 At this time, it is in the clamping position.

[0040] Figure 8 A schematic view of the base provided by the present application in the receiving position, clamping position and over-clamping position.

[0041] Figure 9 A schematic view of the cooperation of the supporting part, clamping part and wafer provided by the present application. Figure 1 At this time, the base is in the receiving position.

[0042] Figure 10 A schematic view of the cooperation of the supporting part, clamping part and wafer provided by the present application. Figure 2 At this time, the base is in the clamping position.

[0043] Figure 11 A schematic view of the wafer clamping mechanism provided by the present application in different states, wherein a is the receiving position, b and d are the clamping positions, and c is the state where the wafer is about to be separated from the bearing surface.

[0044] Wherein, 1-chuck, 2-base, 20-convex column, 21-driving unit, 3-supporting part, 30-bearing part, 31-bearing surface, 32-guiding surface, 4-clamping part, 41-first clamping surface, 42-second clamping surface, 43-inclined surface, 5-wafer, 51-wafer side surface, 52-wafer bottom surface. DETAILED DESCRIPTION

[0045] In order to better understand the technical scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of the present application.

[0046] As shown in Figure 1 , Figure 2 , a wafer clamping mechanism comprises a circular chuck 1 and at least three pedestals 2 arranged along the circumference of the chuck 1, the pedestals 2 are disc-shaped and are arranged in the mounting holes of the chuck 1 with the top surface flush with the top surface of the chuck 1, the pedestals 2 can rotate around the central axis thereof relative to the chuck 1, in the embodiment, the bottom of each pedestal 2 is connected with a driving unit 21, so that the rotation of the pedestals 2 relative to the chuck 1 is realized by the driving unit 21.

[0047] As shown in Figure 3 , each pedestal 2 is provided with a convex column 20 coaxial with the pedestal 2, the convex column 20 is provided with a supporting part 3 and a clamping part 4, and the supporting part 3 and the clamping part 4 are arranged on the two radial sides of the convex column 20.

[0048] The supporting part 3 is column-shaped, and the outer wall thereof is vertically raised to form a bearing part 30, the top of the bearing part 30 forms a bearing surface 31 which can contact the bottom surface 52 of the wafer, and the supporting parts 3 of the plurality of pedestals 2 cooperate with each other to horizontally or nearly horizontally support the wafer 5. The inclination angle of the bearing surface 31 relative to the horizontal plane is 0-15°, that is, the bearing surface 31 can be a horizontal plane or an inclined plane, in the embodiment, the bearing surface 31 is an inclined plane, preferably, the inclination angle of the bearing surface 31 relative to the horizontal plane is 3-15°, that is Figure 5 , the angle β is 3-15°, preferably, the angle β is 7°.

[0049] The clamping part 4 is also column-shaped, and has a first clamping surface 41 arranged vertically and a second clamping surface 42 arranged at an angle to the first clamping surface 41, the first clamping surface 41 is used to contact the side surface 51 of the wafer, that is, to generate a high-direction friction force by applying pressure to the side surface 51 of the wafer, the first clamping surfaces 41 of the plurality of clamping parts 4 cooperate with each other to stably clamp the wafer 5 from the side surface of the wafer 5, preventing the wafer 5 from falling downward. The inclination angle of the second clamping surface 42 relative to the horizontal plane is 30-70°, that is, as Figure 4As shown, the second clamping surface 42 extends obliquely from top to bottom and from inside to outside, with an oblique angle α of 30-70°, preferably 60°. During the rotation of the base 2, the second clamping surface 42 first contacts the wafer side surface 51. At this time, the first clamping surface 41 has not yet fully abutted against the wafer side surface 51. Under the action of the clamping force, the wafer 5 gradually rises along the second clamping surface 42 until the first clamping surface 41 is in close contact with the wafer side surface 51. Of course, the clamping part 4 may only have the first clamping surface 41 and not the second clamping surface 42. To prevent the wafer 5 from flying upwards during rotation, a slope 43 is also provided at the top of the first clamping surface 41. The slope 43 plays a protective role and does not contact the wafer 5 during clamping.

[0050] The base 2 has a receiving position and a clamping position. In the receiving position, the bearing surface 31 contacts the bottom surface 52 of the wafer, or in other words, the wafer 5 is placed horizontally or nearly horizontally on the bearing surface 31. At this time, the first clamping surface 41 does not contact the wafer 5. Figure 6 As shown; the base 2 rotates relative to the chuck 1, so as to Figure 1 Taking the direction shown as an example, when the base 2 rotates counterclockwise relative to the chuck 1, and the base 2 switches from the receiving position to the clamping position, the contact position between the bearing surface 31 and the bottom surface 52 of the wafer gradually changes. Specifically, it moves towards the direction closer to the center of the wafer 5 until the first clamping surface 41 of the multiple clamping parts 4 abuts against the side surface 51 of the wafer, thereby firmly clamping the wafer 5. At this time, the wafer 5 has also detached from the bearing surface 31. Figure 7 As shown.

[0051] Compared to existing technologies, this invention achieves horizontal support and stable clamping of the wafer 5 with only a simple structure such as the base 2; moreover, this invention implements the support and clamping of the wafer 5 in two separate components, as follows: Figure 9 As shown, the support part 3 only needs to perform the function of horizontally supporting the bottom surface 52 of the wafer, and does not need to clamp the side surface 51 of the wafer, as... Figure 10As shown, the clamping part 4 only needs to realize the stable clamping function of the wafer side surface 51, and does not need to horizontally support the wafer bottom surface 52. Then, in order to avoid the problem that the inclination angle of the bearing surface 31 of the supporting part 3 is too large, which causes the wafer 5 to be difficult to guarantee the horizontal degree in the multi-point support condition, the inclination angle of the bearing surface 31 of the supporting part 3 can be as small as possible, because at this time, it is not necessary to consider the situation that the inclination angle is too small, which causes the wafer bottom surface 52 to be unable to be effectively dried due to the capillary effect, and the small inclination angle of the bearing surface 31 can guarantee that the wafer 5 is placed as horizontally as possible, and also avoids the situation that the wafer 5 cannot be effectively clamped due to the inclination of the wafer 5 when the wafer 5 is placed. In addition, the base 2 rotates relative to the chuck 1 to realize the stable clamping of the wafer 5, that is, the wafer 5 has been stably clamped before the chuck 1 rotates at a high speed with the wafer 5. Different from the prior art, the wafer is stably clamped by the centrifugal force caused by the high-speed rotation of the chuck, the wafer is not clamped by the centrifugal force in the present application, and therefore the situation that the wafer slips before the chuck rotates at a high speed will not occur. Furthermore, since the wafer 5 is clamped by the clamping part 4, the wafer 5 is separated from the supporting part 3, and at this time, the space below the wafer 5 is open, which will not cause the capillary high-pressure liquid accumulation phenomenon of the wafer 5 when the wafer 5 is placed and dried, and the cleaning effect of the wafer 5 is better.

[0052] In order to more smoothly place the wafer 5 on the bearing surface 31, a guide surface 32 is further arranged on the supporting part 3, the guide surface 32 extends obliquely from top to bottom and from inside to outside, and the guide surface 32 is located above the bearing surface 31. In fact, the lower end of the guide surface 32 is connected to the highest part of the bearing surface 31. Therefore, the wafer 5 can slide down to the bearing surface 31 along the guide surface 32.

[0053] In order to realize better connection between the wafer clamping mechanism and the upstream and downstream wafer transfer devices, as shown in the figure, Figure 11 As shown, the height of the intersection of the first clamping surface 41 and the second clamping surface 42 is H1, the height of the wafer bottom surface 52 in the receiving position is H2, and the height of the contact point between the wafer bottom surface 52 and the bearing surface 31 when the wafer 5 is separated from the bearing surface 31 is H3. The thickness of the wafer 5 is defined as S, then |H1-H2|≤0.5S, |H3-H2|≤1.5S, and |H3-H2|>|H1-H2|, more specifically, |H1-H2|≤0.5mm, |H3-H2|≤1mm. Therefore, the height of the wafer 5 before and after being clamped is basically unchanged, and during the switching process from the receiving position to the clamping position, the wafer 5 will not be unstable, which ensures that the wafer 5 will not be tilted or dropped, and at the same time, the wafer 5 can be stably clamped and smoothly separated from the bearing surface 31.

[0054] In the embodiment, the number of the pedestals 2 is six, which are evenly spaced along the circumference of the chuck 1, so that the chucking of the wafer 5 is more stable and the force of chucking is more dispersed, and the chucking of wafers of different sizes can also be satisfied. Of course, in other embodiments, the number of the pedestals 2 can be any number between 3 and 9, and the specific number is not limited.

[0055] The pedestal 2 also has an over-clamping position, as shown in the figure. Figure 8 The pedestals 2 rotate in the same direction, for example, clockwise, and can be switched from the receiving position to the clamping position and the over-clamping position in turn.

[0056] A wafer cleaning and drying method is performed based on the wafer clamping mechanism described above, including the following steps,

[0057] S1, the chuck 1 is stationary, and the pedestals 2 rotate relative to the chuck 1 to the receiving position;

[0058] S2, the pedestals 2 are switched from the receiving position to the over-clamping position to determine whether a wafer 5 has been placed on the wafer clamping mechanism, if no wafer 5 is placed, the pedestals 2 are reversely rotated relative to the chuck 1 to the receiving position; if it is determined that a wafer 5 has been placed, an error program is started;

[0059] S3, the transfer device places the wafer 5 horizontally or nearly horizontally on the bearing surface 31 of the supporting part 3 of the plurality of pedestals 2, and the wafer 5 is in line contact with the bearing surface 31, and the clamping part 4 does not contact the wafer 5; in the embodiment, the transfer device is a mechanical hand structure in the prior art;

[0060] Specifically, the above step S3 includes the following sub-steps,

[0061] S31, the transfer device sucks the wafer 5 from the previous work station and moves the wafer 5 horizontally above the chuck 1, and the center of the wafer 5 coincides or tends to coincide with the center of the chuck 1;

[0062] S32, the transfer device is located below the wafer 5, and after receiving the signal that the pedestals 2 are reversely rotated relative to the chuck 1 to the receiving position, the transfer device with the wafer 5 vertically descends until the bottom surface 52 of the wafer 5 contacts the bearing surface 31;

[0063] S33, the transfer device continues to descend by 5-8 mm, and the transfer device after being separated from the wafer 5 moves horizontally away from below the wafer 5;

[0064] S4, the plurality of bases 2 rotate relative to the chuck 1 respectively, the plurality of clamping portions 4 approach the wafer 5 together, and the wafer side surface 51 slides against the second clamping surface 42, the contact position between the wafer bottom surface 52 and the bearing surface 31 gradually approaches the direction where the wafer 5 center is located, until the first clamping surface 41 abuts against the wafer 5 side surface, and the wafer 5 is separated from the bearing surface 31; before the second clamping surface 42 contacts the wafer 5, the wafer 5 produces a slight displacement in the vertical direction, and the falling height is about 1mm;

[0065] S5, the wafer 5 is firmly clamped by the plurality of clamping portions 4, the chuck 1 rotates at high speed, and the rotating speed can reach 3000RPM, so as to realize the spin-drying of the wafer 5;

[0066] S6, the chuck 1 stops rotating, and the transfer device takes away the wafer 5 after the drying is completed;

[0067] Specifically, the above step S6 includes the following sub-steps,

[0068] S61, the plurality of bases 2 rotate reversely relative to the chuck 1 respectively, and switch from the clamping position to the bearing position;

[0069] S62, the transfer device moves horizontally from the position 5-8mm below the wafer 5 to the position directly below the wafer 5;

[0070] S63, after reaching the predetermined position, the transfer device rises until contacting the wafer bottom surface 52, then continues to rise after sucking the wafer 5, until the wafer bottom surface 52 is completely higher than the base 2, and the wafer 5 moves to the next working position with the transfer device.

[0071] The above specific embodiment is used to explain and illustrate the present application, rather than limit the present application, and any modification and change made to the present application within the spirit and protection scope of the claims, falls into the protection scope of the present application.

Claims

1. A wafer clamping mechanism, characterized by: The chuck (1) comprises: a base (2) in number of at least three, which is circumferentially spaced apart along the chuck (1) and can rotate relative to the chuck (1) about a central axis thereof; a supporting portion (3) provided on the base (2) and having a bearing surface (31) capable of contacting a bottom surface (52) of a wafer (5); the supporting portions (3) of the plurality of bases (2) are cooperatively configured to support the wafer (5) horizontally or in a manner tending to be horizontal; a clamping portion (4) provided on the base (2) and having a first clamping surface (41) capable of contacting a side surface of the wafer (5); the base (2) has a supporting position and a clamping position; in the supporting position, the bearing surface (31) contacts the bottom surface (52) of the wafer (5), and the first clamping surface (41) does not contact the wafer (5); when the base (2) rotates relative to the chuck (1) and switches from the supporting position to the clamping position, the contact position of the bearing surface (31) with the bottom surface (52) of the wafer (5) gradually approaches the center of the wafer (5) until the first clamping surface (41) of the clamping portion (4) abuts against the side surface (51) of the wafer (5) to clamp the wafer (5), and the wafer (5) is separated from the bearing surface (31); the first clamping surface (41) is vertically arranged, the clamping portion (4) further comprises a second clamping surface (42) which forms an angle with the first clamping surface (41), and the inclination angle of the second clamping surface (42) relative to the horizontal plane is 30-70°; the thickness of the wafer (5) is S, the height of the intersection of the first clamping surface (41) and the second clamping surface (42) is H1, the height of the bottom surface (52) of the wafer (5) in the supporting position is H2, and the height of the contact point of the bottom surface (52) of the wafer (5) with the bearing surface (31) when the wafer (5) is separated from the bearing surface (31) is H3; the absolute value of the difference between H1 and H2 is less than or equal to 0.5S, the absolute value of the difference between H3 and H2 is less than or equal to 1.5S, and the absolute value of the difference between H3 and H2 is greater than the absolute value of the difference between H1 and H2. The inclination angle of the bearing surface (31) relative to the horizontal plane is 0-15°; or, the inclination angle of the bearing surface (31) relative to the horizontal plane is 3-15°.

2. The wafer clamping mechanism of claim 1, wherein: The number of the bases (2) is six, which are uniformly distributed along the chuck (1) in circumferential direction; the bottom of the base (2) is connected with a driving unit (21).

3. The wafer clamping mechanism of claim 1, wherein: The supporting portion (3) and the clamping portion (4) are arranged on the two radial sides of the base (2).

4. The wafer clamping mechanism of claim 1, wherein: The base (2) further has an over-clamping position, and the base (2) rotates in the same direction to sequentially switch from the supporting position to the clamping position and the over-clamping position.

5. The wafer clamping mechanism of claim 1, wherein: The supporting portion (3) is in a columnar shape, and the outer wall thereof is vertically protruded to form a bearing portion (30), the bearing surface (31) is located on the top surface of the bearing portion (30), and the supporting portion (3) further forms a guide surface (32) which is located above the bearing surface (31).

6. The wafer clamping mechanism of claim 1, wherein: The chuck (1) comprises:

7. A method for cleaning and drying a wafer, relying on the wafer clamping mechanism as claimed in claim 1, characterized in that: a base (2) in number of at least three, which is circumferentially spaced apart along the chuck (1) and can rotate relative to the chuck (1) about a central axis thereof; a supporting portion (3) provided on the base (2) and having a bearing surface (31) capable of contacting a bottom surface (52) of a wafer (5); the supporting portions (3) of the plurality of bases (2) are cooperatively configured to support the wafer (5) horizontally or in a manner tending to be horizontal; a clamping portion (4) provided on the base (2) and having a first clamping surface (41) capable of contacting a side surface of the wafer (5); the base (2) has a supporting position and a clamping position; in the supporting position, the bearing surface (31) contacts the bottom surface (52) of the wafer (5), and the first clamping surface (41) does not contact the wafer (5); when the base (2) rotates relative to the chuck (1) and switches from the supporting position to the clamping position, the contact position of the bearing surface (31) with the bottom surface (52) of the wafer (5) gradually approaches the center of the wafer (5) until the first clamping surface (41) of the clamping portion (4) abuts against the side surface (51) of the wafer (5) to clamp the wafer (5), and the wafer (5) is separated from the bearing surface (31); the first clamping surface (41) is vertically arranged, the clamping portion (4) further comprises a second clamping surface (42) which forms an angle with the first clamping surface (41), and the inclination angle of the second clamping surface (42) relative to the horizontal plane is 30-70°; the thickness of the wafer (5) is S, the height of the intersection of the first clamping surface (41) and the second clamping surface (42) is H1, the height of the bottom surface (52) of the wafer (5) in the supporting position is H2, and the height of the contact point of the bottom surface (52) of the wafer (5) with the bearing surface (31) when the wafer (5) is separated from the bearing surface (31) is H3; the absolute value of the difference between H1 and H2 is less than or equal to 0.5S, the absolute value of the difference between H3 and H2 is less than or equal to 1.5S, and the absolute value of the difference between H3 and H2 is greater than the absolute value of the difference between H1 and H2. The inclination angle of the bearing surface (31) relative to the horizontal plane is 0-15°; or, the inclination angle of the bearing surface (31) relative to the horizontal plane is 3-15°. The number of the bases (2) is six, which are uniformly distributed along the chuck (1) in circumferential direction; the bottom of the base (2) is connected with a driving unit (21). The supporting portion (3) and the clamping portion (4) are arranged on the two radial sides of the base (2). The base (2) further has an over-clamping position, and the base (2) rotates in the same direction to sequentially switch from the supporting position to the clamping position and the over-clamping position. The supporting portion (3) is in a columnar shape, and the outer wall thereof is vertically protruded to form a bearing portion (30), the bearing surface (31) is located on the top surface of the bearing portion (30), and the supporting portion (3) further forms a guide surface (32) which is located above the bearing surface (31). The chuck (1) comprises: a base (2) in number of at least three, which is circumferentially spaced apart along the chuck (1) and can rotate relative to the chuck (1) about a central axis thereof; a supporting portion (3) provided on the base (2) and having a bearing surface (31) capable of contacting a bottom surface (52) of a wafer (5); the supporting portions (3) of the plurality of bases (2) are cooperatively configured to support the wafer (5) horizontally or in a manner tending to be horizontal; a clamping portion (4) provided on the base (2) and having a first clamping surface (41) capable of contacting a side surface of the wafer (5); the base (2) has a supporting position and a clamping position; in the supporting position, the bearing surface (31) contacts the bottom surface (52) of the wafer (5), and the first clamping surface (41) does not contact the wafer (5); when the base (2) rotates relative to the chuck (1) and switches from the supporting position to the clamping position, the contact position of the bearing surface (31) with the bottom surface (52) of the wafer (5) gradually approaches the center of the wafer (5) until the first clamping surface (41) of the clamping portion (4) abuts against the side surface (51) of the wafer (5) to clamp the wafer (5), and the wafer (5) is separated from the bearing surface (31); the first clamping surface (41) is vertically arranged, the clamping portion (4) further comprises a second clamping surface (42) which forms an angle with the first clamping surface (41), and the inclination angle of the second clamping surface (42) relative to the horizontal plane is 30-70 The plurality of bases rotate relative to the chuck respectively, the clamping part is close to the wafer, and the wafer side surface slides against the second clamping surface, the contact position of the wafer bottom surface and the bearing surface gradually approaches the direction where the wafer center is located, until the first clamping surface abuts against the wafer side surface, and the wafer is separated from the bearing surface; The wafer is stably clamped by the plurality of clamping parts, and the chuck is rotated at high speed to realize spin-drying of the wafer; The chuck stops rotating, and the transfer device takes away the wafer after drying.

8. The wafer cleaning spin-drying method of claim 7, wherein: Before the wafer is placed on the bearing surface by the transfer device, the following steps are further included, The base is switched from the bearing position to the over-clamping position to determine whether the wafer clamping mechanism has placed the wafer, if not, the base rotates reversely relative to the chuck to the bearing position.

9. The wafer cleaning spin-drying method of claim 7, wherein: The process that the transfer device horizontally places or tends to horizontally place the wafer on the bearing surface of the plurality of base supporting parts includes the following sub-steps, The transfer device sucks the wafer from the last work station and moves horizontally above the chuck, and the wafer center coincides or tends to coincide with the center of the chuck; The transfer device is located below the wafer and vertically descends with the wafer until the wafer bottom surface contacts the bearing surface; The transfer device continues to descend by 5-8mm, and the transfer device after being separated from the wafer moves horizontally out from below the wafer.

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