Wafer clamping mechanism and wafer cleaning device

Abstract

The invention discloses a wafer clamping mechanism and a wafer cleaning device, and belongs to the technical field of semiconductor manufacturing. The wafer clamping mechanism is used for clamping and protecting a wafer in a wafer back cleaning process, and comprises a support disc used for supporting the wafer to be processed; the gas path system is arranged in the supporting disc and used for providing gas flow for the front face of the wafer so that the wafer can be suspended through the Bernoulli effect in the cleaning process and a gas flow barrier for protecting the front face of the wafer can be formed; the mechanical jacking device is integrated in the supporting disc and is used for lifting the wafer to a picking and placing height higher than a cleaning suspension height when the wafer is picked and placed; and a control unit. Wherein the gas path system and the mechanical jacking device are cooperatively arranged, so that in the process that the mechanical jacking device executes the lifting action, the gas path system maintains a maintaining gas flow lower than the flow of the cleaning suspension gas flow so as to stabilize the position of a wafer and maintain a basic gas barrier in the lifting transition stage.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a wafer clamping mechanism and a wafer cleaning apparatus. Background Technology

[0002] In semiconductor manufacturing, wafer cleaning is a critical process used to remove contaminants such as particles, organic matter, metal ions, and oxides from the wafer surface. With the continuous advancement of technology nodes, the cleanliness requirements for the back side of the wafer (i.e., the non-device side) are becoming increasingly stringent to prevent backside contaminants from transferring to the front side in subsequent processes, affecting device performance and yield. Therefore, backside wafer cleaning has become an indispensable step in advanced manufacturing processes.

[0003] In backside wet cleaning, the wafer is typically placed face down (the side with the finely patterned device) and back up to receive the cleaning solution. This inverted orientation places extremely stringent requirements on the protection of the wafer's front side: First, no functional area on the front side of the wafer must be in physical contact with any object, otherwise it may damage the pattern; only the pre-cut areas at the wafer edges are allowed limited contact. Second, the chemicals used for backside cleaning must be strictly confined to the back side of the wafer and must never flow or splash onto the front side, otherwise it will cause circuit corrosion or contamination. Third, even in the edge areas where contact is permitted, the contact area should be as small as possible (usually not exceeding 2 mm) to minimize mechanical stress and the risk of contamination.

[0004] To meet the above requirements, the industry currently widely uses air-floating chucks (often called "Bernoulli chucks") based on Bernoulli's principle to support inverted wafers. The basic principle is to supply high-speed airflow into the narrow space between the wafer's front side and the chuck surface. Utilizing the pressure difference generated by the airflow velocity difference, the wafer is stably suspended without large-area physical contact, forming an airflow barrier on its front side. This barrier not only effectively blocks cleaning fluid that may splash from below but also achieves non-contact support for the wafer's front side, thus fundamentally avoiding the problems of physical contact contamination and chemical corrosion.

[0005] However, traditional Bernoulli chucks present significant technical bottlenecks in practical mass production applications. The buoyancy force generated by the Bernoulli effect is limited, which typically restricts the stable levitation height of the wafer during the process to within approximately 1 mm. This extremely small gap is acceptable during the process itself, but it poses significant challenges during the wafer loading and unloading stages before and after the process begins. The end effector of the wafer handling robot needs to precisely extend into this narrow gap for operation, making it highly susceptible to collisions with the wafer or chuck due to alignment deviations or vibrations. This can cause wafer breakage or equipment damage, severely impacting operational safety and production cycle time.

[0006] In summary, there is an urgent need for a wafer clamping mechanism design that can reliably utilize the Bernoulli effect to provide non-contact support and effective airflow protection for the front side of the wafer during the back-side cleaning process. It can also fundamentally simplify and solve the operational problems caused by insufficient suspension height during the wafer pick-and-place stage, thereby improving the reliability, safety, and production efficiency of the entire cleaning process. Summary of the Invention

[0007] In view of this, embodiments of this application provide a wafer clamping mechanism and a wafer cleaning apparatus to at least partially solve the above-mentioned problems.

[0008] According to a first aspect of the embodiments of this application, a wafer clamping mechanism is provided for clamping and protecting a wafer during a backside cleaning process, comprising:

[0009] Support disks are used to support the wafers to be processed.

[0010] An air path system, located within the support disk, is used to provide airflow to the front side of the wafer, thereby suspending the wafer during the cleaning process through the Bernoulli effect and forming an airflow barrier that protects the front side of the wafer.

[0011] A mechanical lifting device, integrated into the support plate, is used to lift the wafer to a height higher than the cleaning suspension height during wafer pick-up and drop-off.

[0012] And, control unit;

[0013] The gas path system is configured in conjunction with the mechanical lifting device so that during the lifting action performed by the mechanical lifting device, the gas path system maintains a sustaining airflow that is lower than the flow rate of the cleaning and suspension airflow, so as to stabilize the wafer position and maintain the basic gas barrier during the lifting transition phase.

[0014] The control unit is configured to execute the following cooperative control logic:

[0015] In cleaning mode, the air circuit system is controlled to provide cleaning and suspended airflow, and the mechanical lifting device is controlled to be in a descending state;

[0016] In wafer pick-and-place mode, the mechanical lifting device is activated to lift the wafer, and the gas path system is simultaneously switched to the maintaining gas flow.

[0017] In some embodiments, the mechanical lifting device includes:

[0018] Multiple push rods are movably inserted into the support disk, with their tips used to contact the removable area at the edge of the wafer;

[0019] The drive chamber corresponding to each of the push rods is configured to selectively apply a force to the push rod, either keeping it in a descending state or lifting it upwards, by switching the air path.

[0020] In some embodiments, the drive cavity includes an upper chamber and a lower chamber separated by the shaft of the push rod;

[0021] The air passage system includes a first air intake passage and a second air intake passage;

[0022] When the first air intake is opened and air is supplied to the upper chamber, the push rod is pressed into the lowered position;

[0023] When the second air intake is opened and air is supplied to the lower chamber, the push rod is driven to the lifting position.

[0024] In some embodiments, a dynamic sealing structure is provided between the push rod and the support plate, and when the push rod is in the lowered position, the gas from the first air intake is configured to fill the mating gap between the push rod and the support plate to form an airtight barrier.

[0025] In some embodiments, the wafer clamping mechanism further includes a clamping and positioning component, which includes:

[0026] Multiple clamping pins are rotatably disposed on the edge of the support plate; and

[0027] The drive ring, which is linked to the clamping pin, is used to drive the clamping pin to rotate in order to clamp or release the wafer.

[0028] In some embodiments, the wafer clamping mechanism further includes:

[0029] An annular locking disc is located on the outer edge of the top of the support disc, and its outer side wall is provided with a wedge-shaped groove to block and guide the splashed cleaning fluid during the cleaning process.

[0030] In some embodiments, the pneumatic system includes multiple sets of air vents:

[0031] The first set of vents is located in the central area of ​​the support disk and is used to provide the main airflow that suspends the wafer;

[0032] A second set of vents is arranged around the clamping pin to create localized airflow protection around the clamping pin, preventing cleaning fluid from seeping in along the clamping pin.

[0033] In some embodiments, the second set of pores includes:

[0034] The first aperture air hole is used to blow air into the annular groove of the clamping pin to form an upward airflow sealing wall that surrounds the clamping pin.

[0035] The second aperture air hole is disposed on the locking plate and extends outward. Its aperture is smaller than that of the first aperture air hole, so that the airflow remains full in the annular groove area.

[0036] In some embodiments, the drive ring is provided with toothed segments that mesh with the gear portion of the clamping pins. The drive ring is driven by a drive member to rotate or oscillate, thereby driving all the clamping pins to rotate synchronously.

[0037] In some embodiments, the first set of pores is distributed in multiple rings on the support disk, with different rings having different pore diameters and / or tilt angles to accommodate wafers of different thicknesses or warpages, thereby ensuring uniform suspension height.

[0038] In some embodiments, the inner edge of the locking disc is provided with a through placement hole for inserting the clamping pin; the inner sidewall of the placement hole includes a first arc segment, a second arc segment and a straight segment, which abut against different positions along the axial direction of the clamping pin to change the distance of the clamping pin relative to the center of the support disc, thereby achieving the clamping or release of the wafer.

[0039] In some embodiments, the placement hole is a stepped hole, with the first arc segment located at the lower part of the placement hole, and the second arc segment and the straight segment located at the upper part of the placement hole.

[0040] In some embodiments, the clamping pin includes a first cylindrical segment, and an abutment post is offset above the first cylindrical segment to abut against the edge of the wafer and clamp the wafer; the first cylindrical segment and the abutment post are horizontally staggered to form a locking platform, which abuts against the stepped portion of the placement hole.

[0041] In some embodiments, the outer diameter of the first cylindrical segment matches the size of the first arc segment, and the outer diameter of the abutting post matches the size of the second arc segment.

[0042] In some embodiments, the flow rate of the sustaining airflow is configured to be 10% to 30% of the flow rate of the cleaning suspension airflow.

[0043] In some embodiments, the mechanical lifting device is configured to lift the wafer to a pick-up and drop height of 3 mm to 5 mm.

[0044] According to a second aspect of the embodiments of this application, a wafer cleaning apparatus is provided, comprising:

[0045] Enclosure to provide a wafer processing chamber;

[0046] The wafer clamping mechanism described above is located within the wafer processing chamber and is used to support and protect the wafer.

[0047] A cleaning fluid supply unit is used to spray cleaning fluid onto the back side of the wafer;

[0048] The control unit or an integrated control system is communicatively connected to the wafer clamping mechanism and the cleaning fluid supply unit to coordinate the execution of the collaborative control logic.

[0049] In some embodiments, the control system is further configured to:

[0050] In cleaning mode, the gas flow rate and pressure of the gas path system are adjusted according to preset process parameters to control the suspension height of the wafer and the strength of the airflow barrier.

[0051] The beneficial effects of this invention include:

[0052] a. This system achieves a safe, efficient, and seamless transition between wafer handling and high-quality cleaning processes. By deeply integrating a non-contact airflow suspension protection system based on the Bernoulli effect with an independently controllable mechanical lifting device, this mechanism creatively solves the problems of difficult robot operation and high collision risk caused by the small suspension gap during wafer handling in traditional Bernoulli chucks. During cleaning, the wafer is stably suspended at a low position, forming an effective protective barrier; during wafer handling, it can be safely lifted several millimeters, providing ample and safe operating space for the robot, significantly reducing wafer breakage and equipment damage rates, and improving production cycle time and overall equipment safety.

[0053] b. Provides proactive and highly reliable protection for the entire front side of the wafer in multiple dimensions. The gas path system adopts a zoned and independently controllable design, which not only achieves uniform and stable wafer suspension through the central main airflow, but also constructs targeted "airflow sealing walls" through localized airflow around key areas such as the clamping pins. Combined with an optimized mechanical seal structure, a dual protection system of "airflow barrier as the main component and mechanical seal as the auxiliary component" is formed, which can effectively resist the impact, splashing, and capillary penetration of cleaning fluid, ensuring that the fine patterned areas on the front side of the wafer are absolutely protected in the harsh back-side wet cleaning environment, thereby improving process tolerance and product yield.

[0054] c. It achieves precise, low-stress, and low-contamination clamping and positioning of the wafer edge. The clamping and positioning components, through precise mechanical linkage and aperture design, ensure that the clamping force is always applied accurately and uniformly to the pre-defined removable area on the wafer edge. The contact area is small, and contamination can be reduced through the tip material and purging design. Synchronous drive and position feedback mechanisms ensure the consistency and repeatability of the clamping action, achieving reliable limiting at high-speed rotation while minimizing the risk of mechanical damage to the wafer and the introduction of particulate contamination.

[0055] d. Improved the automation level and process adaptability of the entire cleaning process. The integrated control unit can automatically coordinate the action sequence of the air circuit system, mechanical lifting device, and clamping and positioning components according to preset programs, and can adjust the airflow distribution according to parameters such as wafer thickness and warpage to achieve uniform control of the suspension height. This not only ensures the consistency and stability of the process, but also significantly enhances the equipment's adaptability to different process conditions and wafer specifications. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0057] Figure 1 This is a schematic diagram of a wafer clamping mechanism provided in an embodiment of the present invention;

[0058] Figure 2 yes Figure 1 A partial cross-sectional view of the mechanical lifting device in the embodiment;

[0059] Figure 3 yes Figure 2 A magnified view of a section at point A in the middle;

[0060] Figure 4 This is a schematic diagram of the top rod of the mechanical lifting device provided in an embodiment of the present invention in the lifting position;

[0061] Figure 5 This is a cross-sectional view of a wafer clamping mechanism provided in another embodiment of the present invention;

[0062] Figure 6 yes Figure 5 A magnified view of a section at point B in the middle;

[0063] Figure 7 This is a schematic diagram of a locking disc provided in an embodiment of the present invention;

[0064] Figure 8 yes Figure 7 A magnified view of a section at point C;

[0065] Figure 9 This is a schematic diagram of a clamping pin provided in an embodiment of the present invention;

[0066] Figure 10 This is a schematic diagram of the clamping pin in different positions according to an embodiment of the present invention;

[0067] Figure 11This is a schematic diagram of a wafer cleaning apparatus provided in an embodiment of the present invention. Detailed Implementation

[0068] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of this application.

[0069] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0070] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0071] Figure 1 This is a schematic diagram of a wafer clamping mechanism 100 according to an embodiment of the present invention, used to clamp and protect the wafer during the back-side cleaning process. It should be noted that during back-side cleaning, the wafer is positioned with its back side facing upwards. The wafer clamping mechanism 100 includes:

[0072] Support disk 10 is used to support the wafer to be processed;

[0073] The gas path system, located inside the support disk 10, is used to provide airflow to the front side of the wafer so that the wafer is suspended during the cleaning process by the Bernoulli effect, thereby forming an airflow barrier to protect the front side of the wafer and prevent the front side of the wafer from directly contacting the top surface of the support disk 10; the composition and connection relationship of the gas path system will be described in detail below.

[0074] The mechanical lifting device 20, integrated in the support plate 10, is used to lift the wafer to a certain pick-up and place height during wafer pick-up and place; wherein the pick-up and place height is higher than the suspension height during wafer cleaning.

[0075] A control unit (not shown) is used to coordinate and control the cooperative operation of the pneumatic system and the mechanical lifting device 20;

[0076] The clamping and positioning component 30 is used to limit the edge of the wafer during the cleaning process, and can clamp the wafer horizontally and reliably.

[0077] The air path system and the mechanical lifting device 20 are integrated and coordinated through the control unit, forming the key to this invention. Their coordination lies in the following: during the wafer pick-and-place operation, when the mechanical lifting device 20 lifts the wafer, the control unit synchronously controls the air path system to maintain a specific sustaining airflow lower than the cleaning suspension airflow rate, preferably 10%-30% of the cleaning flow rate. This sustaining airflow plays a crucial role in the lifting transition phase: on the one hand, it provides a soft "air cushion" at the moment the wafer detaches from the large-area air flotation support but is not yet fully and stably supported by the mechanical lifting device, effectively preventing horizontal displacement or tilting of the wafer and ensuring the verticality and stability of the lifting path; on the other hand, it continuously forms a weak but continuous basic gas barrier on the wafer front, providing basic positive pressure protection for the wafer front during the relatively open pick-and-place phase with robotic arm intervention, blocking potential environmental contaminants. This collaborative control logic, which actively maintains and optimizes the airflow throughout the mechanical operation, has been experimentally verified in the wafer cleaning production site.

[0078] To verify and optimize the flow rate range of the sustaining airflow, the applicant conducted a systematic experiment. The experiment was conducted in a simulated cleaning environment using a 300mm standard silicon wafer (775μm thick). The horizontal offset, attitude stability, and front-side particle contamination protection effect of the wafer during mechanical lifting were compared under different sustaining airflow rates (expressed as a percentage of the cleaning suspension airflow rate). The cleaning suspension airflow was set to a flow rate of Q0, corresponding to a stable wafer suspension height of 0.5mm.

[0079] The experimental results are shown in the table below:

[0080]

[0081] From the data above, we can see that:

[0082] a. Offset and Stability: When the airflow is maintained below 10%, the wafer does not receive sufficient air cushion effect at the moment of detachment from the main air buoyancy support, resulting in a significant increase in horizontal offset and tilt angle, increasing the risk of collision with the robotic arm or surrounding structures. When the flow rate reaches 10%, the offset has decreased to below an acceptable safety threshold (<0.5mm), and the attitude is stable.

[0083] b. Contamination Protection Effectiveness: In an open back cavity environment, maintaining a positive pressure barrier formed by airflow is crucial to preventing airborne particulate contamination of the wafer's front side. Experiments show that when the flow rate is below 10%, the protective effect is weak, and the particle count increases significantly. The protective effect is close to optimal when the flow rate is in the 20%-30% range; further increasing the flow rate yields diminishing marginal returns in terms of further contamination suppression.

[0084] c. Determining the upper limit of flow rate: While maintaining a flow rate exceeding 30% still ensures good stability and protection, it brings two negative impacts: First, gas consumption increases proportionally, which is detrimental to equipment operating costs; second, the increased pressure of the airflow on the lower surface of the wafer generates a considerable reverse force on the mechanical lifting device, potentially slowing down the lifting speed or requiring the lifting mechanism to provide greater driving force, thus reducing system efficiency. When the flow rate exceeds 50%, this reverse force begins to interfere with the smoothness of the lifting operation.

[0085] Based on the above experimental data and technical balance, setting the maintenance airflow rate to 10% to 30% of the cleaning suspension airflow rate can simultaneously achieve excellent wafer stabilization (offset <0.3mm) and effective frontal base contamination protection (minimal increase in particulate contamination) during the lifting transition phase, while avoiding unnecessary energy consumption and system interference. A more preferred range is 15% to 25%, within which the system's overall performance is most balanced and efficient.

[0086] Figure 2 yes Figure 1 The partial cross-sectional view of the mechanical lifting device 20 in this embodiment shows that the mechanical lifting device 20 includes a lifting rod 21 and a driving cavity 22. The lifting rod 21 is movably inserted into the support plate 10, and its top end is used to contact the removable area of ​​the wafer edge. The driving cavity 22 corresponds to the lifting rod 21, with one driving cavity 22 for each lifting rod 21. The driving cavity 22 is configured to selectively apply force to the lifting rod 21 through air path switching, so that the lifting rod 21 is held in a descending state or an upward lifting state. When the lifting rod 21 is held in the descending state, the wafer clamping mechanism 100 is in the cleaning mode; while when the lifting rod 21 is in the upward lifting state, the wafer clamping mechanism 100 is in the wafer pick-and-place mode.

[0087] Figure 3 yes Figure 2The enlarged view at point A shows that in this embodiment, the drive cavity 22 includes an upper chamber 22a and a lower chamber 22b, which are separated by the rod body of the push rod 21.

[0088] Specifically, a circular partition plate 21a is disposed on the rod body of the push rod 21, and the partition plate 21a is coaxially disposed in the lifting hole 11 forming the driving cavity 22. Figure 2 (As shown in the diagram). Further, the partition plate 21a divides the drive cavity 22 to form relatively independent upper chamber 22a and lower chamber 22b.

[0089] The push rod 21 can move along the length of the lifting hole 11 to change the distance between the top of the push rod 21 and the top surface of the support disk 10, thereby changing the gap between the wafer and the support disk 10.

[0090] This invention employs an integrated airflow design, with the airflow system including a first air intake 41 and a second air intake 42. The first air intake 41 is connected to the upper chamber 22a, and the second air intake 42 is connected to the lower chamber 22b. This means that the airflow used for levitation protection and the airflow used to drive mechanical lifting originate from the same control system, and can even share a portion of the air source, achieving a highly compact structure and unified control, unlike existing technologies that separate the levitation and lifting airflow paths.

[0091] The control unit switches the air path of the drive chamber 22 by controlling the proportional valves or switching valves provided on the first air intake 41 and the second air intake 42. When the first air intake 41 is opened and supplies air to the upper chamber 22a, the push rod 21 is pressed into the lowered position, such as... Figure 2 and Figure 3 As shown; when the second air intake 42 is opened and air is supplied to the lower chamber 22b, the push rod 21 is driven to the lifting position, as shown. Figure 4 As shown; at this time, the distance between the wafer and the top surface of the support disk 10 is raised to a pick-up and put-down height of 3mm to 5mm, providing the robot arm with ample and safe operating space.

[0092] Figure 3 In the illustrated embodiment, the mechanical lifting device 20 further includes a spring 23, which is sleeved on the body of the lifting rod 21 and located above the partition plate 21a. That is, one end of the spring 23 abuts against the top surface of the partition plate 21a, and the other end abuts against the top surface of the lifting hole 11.

[0093] When the push rod 21 is in the raised position, the spring 23 is in a compressed state; when the first air inlet 41 is opened and air is supplied to the upper chamber 22a, the push rod 21 is maintained in the lowered position under the action of the gas and the spring 23.

[0094] Furthermore, when the push rod 21 is in the lowered position, the gas from the first air inlet 41 fills the mating gap between the push rod 21 and the support plate 10. More importantly, a precision dynamic sealing structure (such as a polymer sealing ring) is provided between the push rod 21 and the lifting hole 11 of the support plate 10. In cleaning mode, the continuous gas from the first air inlet 41 not only presses down the push rod 21, but also forms a positive pressure "gas-tight barrier" inside the dynamic sealing structure. This barrier effectively prevents the cleaning fluid from seeping into the drive cavity 22 through the moving gap of the push rod 21 by capillary action, thereby fundamentally solving the problem of sealing and preventing contamination of mechanical moving parts in harsh wet cleaning environments, and ensuring the long-term operational reliability of the mechanical lifting device 20.

[0095] In some embodiments, the top surface of the push rod 21 is configured with a slightly convex spherical surface, or it is inlaid with a low-friction, chemically resistant polymer gasket (such as polyetheretherketone, polyimide, etc.) to optimize the contact method between the top surface of the push rod 21 and the removable area on the back side of the wafer, ensuring point contact while minimizing mechanical stress and particulate contamination on the back side of the wafer. Furthermore, the push rod 21 may have a micro-purge air path (not shown in the figure) inside, which can be independently controlled or branched into the first air inlet path 41. After the push rod 21 descends and resets, the control unit can instruct the introduction of a small amount of high-purity inert gas into the micro-purge air path. The airflow is ejected from the top micro-hole, directly purging the contact area between the push rod and the wafer, blowing away any trace amounts of liquid or particles, further ensuring the cleanliness of the contact area. This active contamination control measure is not mentioned in the prior art.

[0096] In this invention, there are multiple top rods 21, which are distributed at intervals along the circumference of the support disk 10 to disperse the support points of the wafer and ensure uniform lifting of the wafer.

[0097] Furthermore, the support plate 10 is also equipped with a lifting exhaust port 12, which is connected to the lifting port 11. The lifting exhaust port 12 is arranged opposite to the second air inlet 42 so that when the second air inlet 42 is opened, part of the gas in the lower chamber 22b is discharged through the lifting exhaust port 12, thereby forming a relatively stable air pressure inside the lower chamber 22b to reliably lift the wafer.

[0098] Figure 5 This is a cross-sectional view of a wafer clamping mechanism 100 provided in another embodiment of the present invention. In this embodiment, the clamping and positioning component 30 includes:

[0099] Clamping pin 31 is rotatably disposed on the edge of support plate 10;

[0100] The drive ring 32, which is linked with the clamping pin 31, is used to drive the clamping pin 31 to rotate, thereby achieving the clamping or release of the wafer.

[0101] Figure 6 yes Figure 5 In the enlarged view at point B, the outer periphery of the drive ring 32 is provided with toothed segments, and a gear portion is provided below the clamping pin 31. This gear portion meshes with the teeth of the toothed segments of the drive ring 32, enabling the rotating drive ring 32 to drive the clamping pin 31 to rotate along its axis. Specifically, the drive ring 32 has toothed segments that mesh with the gear portion of the clamping pin 31. The drive ring 32 rotates or oscillates under the drive of a driving component, thereby causing all the clamping pins 31 to rotate synchronously.

[0102] It should be noted that the movement of the drive component and drive ring 32 is also controlled by the control unit to ensure precise synchronization between the clamping action and the cleaning and pick-up / placement mode.

[0103] In some embodiments, the drive element is preferably a structure consisting of a linear cylinder or a servo motor in conjunction with a ball screw. It is connected to the drive ring 32 via a crank-connecting rod mechanism or a shift fork mechanism, converting linear motion into a limited-angle rotation of the drive ring 32. The control unit configured in the wafer clamping mechanism 100 can precisely control the stroke of the drive element, thereby precisely controlling the rotation angle of all clamping pins 31, ensuring the consistency and repeatability of the clamping force. Furthermore, a position sensor can be integrated into the drive ring 32 or the drive element to provide real-time feedback on the state of the clamping pins 31 in "clamped," "released," or intermediate positions, achieving closed-loop control.

[0104] Figure 1 In the illustrated embodiment, the support disk 10 further includes an annular locking disk 50, which is disposed radially outside the support disk 10 and located at the outer edge of the top of the support disk 10.

[0105] Furthermore, the outer wall of the locking disc 50 is provided with a wedge-shaped groove 51 to block and guide the splashed cleaning fluid during the cleaning process, so as to prevent the cleaning fluid from entering the interior of the wafer clamping mechanism 100.

[0106] In some embodiments, the cross-sectional shape of the wedge groove 51 can be optimized as a composite curved surface, for example, including a Venturi tube segment that converges and then diffuses. When splashed droplets enter the groove, the high-speed rotating wafer and support disk drive the surrounding gas to form a tangential airflow. This airflow is accelerated when it passes through the Venturi segment of the wedge groove 51, producing a stronger centrifugal ejection effect on the droplets. At the same time, due to pressure changes, some gas may carry trace droplets from the small guide holes (not shown in the figure) at the bottom of the groove and be actively drawn out and discharged to the bottom of the cavity, thereby achieving more active droplet interception and removal, and reducing the risk of liquid accumulation in the locking disk area.

[0107] In this invention, the gas path system configured in the wafer clamping mechanism 100 includes multiple sets of gas holes:

[0108] The first set of vents 43 is located in the central area of ​​the support disk 10 and is used to provide the main airflow to suspend the wafer;

[0109] The second set of vents 44 is arranged around the clamping pin 31 to form a local airflow protection around the clamping pin 31 to prevent the cleaning fluid from seeping in along the clamping pin 31.

[0110] Furthermore, the second set of pores 44 includes a first-diameter pore 44a and a second-diameter pore 44b, such as... Figure 6 As shown. The first aperture air hole 44a is used to blow air into the annular groove 31a of the clamping pin 31 to form an upward airflow; the second aperture air hole 44b is provided on the locking plate 50 and extends outward, and its aperture is smaller than the size of the first aperture air hole 44a, so that the airflow remains full in the annular groove 31a area.

[0111] The high-speed airflow ejected from the first aperture vent 44a forms an upward-moving annular "airflow sealing wall" within the annular groove 31a of the clamping pin 31. Combined with the physical shielding of the locking disc 50, this "airflow sealing wall" can effectively resist the tangential splashing and capillary creep effect of the cleaning fluid caused by the high-speed rotation of the wafer, thus constituting active protection against the critical penetration path of the clamping pin 31.

[0112] To enhance protection of the wafer edge and prevent capillary penetration of the cleaning fluid, one or more annular sealing lips or O-rings (not shown in the figure) are added above the annular groove 31a of the clamping pin 31 to form a sealing structure. This sealing structure can be made of chemical-resistant materials such as perfluoroether rubber. When the clamping pin 31 is installed in place, this sealing structure forms a tight contact with the inner wall of the placement hole 52. At the same time, the airflow from the second set of vents 44, especially the airflow blown out from the first aperture vent 44a, is guided below the sealing structure to form a positive pressure air curtain. This design forms a three-fold progressive protection from bottom to top: the first layer is the active purging of the "airflow sealing wall"; the second layer is the mechanical blocking of the sealing lip / ring; and the third layer is the isolation of the positive pressure air curtain above the sealing ring. The three layers work together to greatly enhance the sealing reliability of the wafer front edge area under high pressure and high flow rate cleaning fluid spraying environment, and almost eliminate any possibility of cleaning fluid seeping up along the gap of the clamping pin 31. Experiments show that, compared to solutions with only traditional mechanical seals or simple air blowing, this triple protection design can reduce the liquid penetration rate in the clamping pin 31 area by more than 95%.

[0113] In this invention, the first group of vents 43 is distributed in a ring-like pattern on the support disk 10. The vents in different rings have different apertures and / or tilt angles, and are connected to independently controllable air path branches to adapt to wafers of different thicknesses or warpages, ensuring uniform suspension height. This feature allows the invention to dynamically adjust the airflow distribution according to the specific morphology of the wafer (e.g., for ultra-thin wafers with a thickness <0.8mm or wafers with severe center / edge warpage), achieving globally uniform support and overcoming the limitation of traditional Bernoulli chucks that require high wafer flatness.

[0114] The control unit can independently control the first group of vents 43 by zone. Based on the preset process formula or real-time feedback from the integrated height / pressure sensor, it can dynamically adjust the gas flow and pressure in different areas to achieve active compensation and precise stable control of the global suspension attitude of the wafer.

[0115] In this invention, the control unit is specifically configured to execute the following collaborative control logic to achieve safe and seamless switching between the cleaning mode and the wafer pick-and-place mode:

[0116] In cleaning mode, the air path system is controlled to provide full-flow cleaning suspension airflow (e.g., to stably suspend the wafer at a height of about 0.5 mm), and the mechanical lifting device 20 is controlled to be in a lowering and locking state (i.e., the first air inlet 41 is opened), while the clamping and positioning component 30 is controlled to be in a clamping state.

[0117] In the wafer pick-and-place mode, the control process specifically includes: First, controlling the clamping and positioning component 30 to move to the open state, completely releasing the lateral constraint on the wafer. Then, the control unit simultaneously executes two commands: one is to control the mechanical lifting device 20 to start (i.e., switch to opening the second air inlet 42); the other is to control the air circuit system to reduce the gas flow rate of the first set of air holes 43 to 10%-30% of the cleaning flow rate, switching to the "maintaining airflow" mode. Under this coordinated control, the push rod 21 of the mechanical lifting device 20 begins to rise, while the maintaining airflow continues to play a role in stabilizing the wafer and providing basic protection during the lifting transition phase. After the wafer is smoothly lifted to a pick-and-place height of 3-5mm, the robot arm can safely enter to perform the wafer pick-and-place operation. Experimental results show that, compared to the method of directly shutting off the airflow and using pure mechanical lifting, this collaborative control logic reduces the horizontal offset of the wafer during the wafer pick-up and drop process by more than 70%, and completely avoids wafer jitter or uncontrolled adsorption caused by the sudden disappearance of airflow. The wafer pick-up success rate is significantly improved, which is crucial for fragile thin wafers.

[0118] In some preferred embodiments, the control logic further includes a closed-loop adjustment step. For example, during the lifting process, the control unit receives feedback signals in real time from a wafer suspension height sensor mounted on the support plate 10 or within the cavity. If tilting or height fluctuations of the wafer are detected during lifting, the control unit can dynamically fine-tune the flow rate of the maintaining airflow (within the range of 10%-30%) or slightly adjust the pressure of the second air intake 42 (i.e., the lifting speed) to correct the wafer attitude in real time and ensure the verticality and stability of the lifting path. This closed-loop collaborative control based on real-time sensing further enhances the system's adaptability to process disturbances and different wafer conditions.

[0119] In some embodiments, the gas path system employs a zoned independent control strategy. Specifically, the first group of air vents 43 can be further divided into a central region and several concentric ring regions, each region connected to an independent gas path and control valve. The control unit can dynamically adjust the gas flow rate and pressure in the corresponding region based on real-time sensor feedback of the suspension height data of different regions of the wafer. These sensors include, but are not limited to, height sensors and pressure sensors. For example, when a slight warping in the wafer edge region causes a lower suspension height, the gas supply pressure in the corresponding ring region air vent can be increased, thereby achieving active compensation and precise stable control of the global wafer suspension attitude, effectively addressing the challenges posed by wafer warping.

[0120] As a more refined control method, the different rings of vents can be connected to different air supply lines and controlled by independent proportional valves or mass flow controllers. The control unit can pre-store "suspension recipes" for various wafer sizes (such as 300mm, 200mm, etc.) and common warpage patterns. When a wafer size is loaded, the control unit automatically calls the corresponding recipe, adjusting the airflow ratio and pressure of each ring of vents to achieve optimal suspension support for that wafer size, ensuring uniform airflow pressure distribution across the entire lower surface of the wafer and maintaining a stable suspension height at the target value (e.g., 0.5mm ± 0.05mm).

[0121] Furthermore, a micro-airflow channel (not shown) extending axially can also be provided inside the body of the clamping pin 31. This channel can communicate with some of the air holes in the second set of air holes 44, or be supplied with air independently. The airflow flows out from the lateral micro-holes in the middle or upper part of the clamping pin 31, forming a bottom-up surrounding airflow that is close to the shaft of the clamping pin 31. This "built-in airflow protection" can more accurately form a positive pressure barrier at the mating gap between the clamping pin 31 and the placement hole 52. Especially for wafers with extremely thin thickness (such as less than 0.8 mm) or large warpage, it can effectively compensate for the weakening of the local airflow barrier caused by wafer deformation, ensuring no blind spots in edge protection.

[0122] Figure 7This is a schematic diagram of a locking disc 50 provided in an embodiment of the present invention. The inner edge of the locking disc 50 is provided with a plurality of through placement holes 52 for inserting corresponding clamping pins 31.

[0123] Figure 8 yes Figure 7 The enlarged view at point C shows that the inner wall of the placement hole 52 includes a first arc segment 52a, a second arc segment 52b, and a straight segment 52c. These three segments abut against different positions along the axis of the clamping pin 31 to change the distance between the clamping pin 31 and the center of the support disk 10, thereby achieving the clamping or release of the wafer.

[0124] The placement hole 52 is a stepped hole. The first arc segment 52a is located at the lower part of the placement hole 52, and the second arc segment 52b and the straight segment 52c are located at the upper part of the placement hole 52, so that the rotating clamping pin 31 abuts against different positions of the placement hole 52, thereby changing the position of the clamping pin 31.

[0125] Figure 9 This is a schematic diagram of a clamping pin 31 provided in an embodiment of the present invention. The clamping pin 31 includes a main body rod, the lower end of which is provided with a gear portion, and the upper part of which is provided with an annular groove 31a.

[0126] Furthermore, the clamping pin 31 also includes a first cylindrical section 31b, on which an abutment post 31c is disposed; wherein, the abutment post 31c is biased and disposed on the upper part of the first cylindrical section 31b, and the abutment post 31c is used to abut against the edge of the wafer to clamp the wafer.

[0127] Figure 9 In the middle, the first cylindrical section 31b and the abutment post 31c are horizontally staggered to form a locking platform 31d, which abuts against the stepped portion 52d of the placement hole 52. Figure 8 (As shown).

[0128] Figure 10 This is a schematic diagram of the clamping pin 31 in different positions according to an embodiment of the present invention. The outer diameter of the first cylindrical segment 31b matches the size of the first arc segment 52a, so that the clamping pin 31 rotates along its axis near the inner side of the locking disc 50 to change the position of the abutment post 31c on it.

[0129] Specifically, Figure 10 In (a), the clamping and positioning assembly 30 is in a closed state, the abutment post 31c of the clamping pin 31 faces the inside of the support disk 10, and the outer wall of the abutment post 31c abuts against the edge of the wafer. Figure 10In (b) and (c), the clamping and positioning assembly 30 is in the open state, and the abutment post 31c of the clamping pin 31 is offset from the inner side of the support plate 10, increasing the distance between the abutment post 31c and the center of the support plate 10. The outer wall of the abutment post 31c abuts against the second arc segment 52b, while the locking platform 31d of the locking pin 31 is located above the step portion 52d. When the clamping pin 31 rotates around its axis to... Figure 10 When the position shown in (c) is reached, the abutment post 31c rotates to the intersection of the second arc segment 52b and the straight segment 52c and gets stuck, which is the limit open position of the clamping and positioning assembly 30.

[0130] It should be noted that the outer diameter of the abutment post 31c matches the size of the second arc segment 52b so that after the clamping pin 31 is rotated to the open state, the surface contact between the abutment post 31c and the second arc segment 52b can be used to ensure the smooth operation of the clamping and positioning assembly 30.

[0131] In this invention, the control unit configured in the wafer clamping mechanism 100 is used to execute the following control logic:

[0132] In cleaning mode, the control air system provides cleaning airflow and controls the mechanical lifting device 20 to be in a descending state; specifically, the first air inlet 41 is opened and air is supplied to the upper chamber 22a. Under the action of the gas and the spring 23, the push rod 21 is maintained in the descending position.

[0133] In wafer pick-and-place mode, the control air circuit system switches or adjusts the airflow, and controls the mechanical lifting device 20 to start, raising the wafer to the pick-and-place height. Specifically, when the second air inlet 42 is opened and air is supplied to the lower chamber 22b, the push rod 21 is driven to the lifting position; at this time, the distance between the wafer and the top surface of the support plate 10 is at its maximum, which facilitates wafer pick-and-place.

[0134] As one of the core improvements of this invention, the control unit employs a coordinated control strategy of mechanical lifting and airflow system when executing the wafer pick-up and drop-off mode. Specifically, during the process of activating the mechanical lifting device 20 to lift the wafer, the control unit does not simply shut off or significantly reduce the main suspension airflow, but instead instructs the air path system to switch to "lifting maintenance mode". In this mode, the gas flow rate of the first set of air holes 43 is reduced to 10%-30% of the cleaning flow rate, but still maintains a certain low flow supply. The function of this low flow airflow is: firstly, to provide a certain air cushion effect during the transition stage when the wafer is detached from the large-area air flotation support but has not yet been fully and stably supported by multiple push rods 21, preventing the wafer from shifting horizontally or tilting due to uneven force; secondly, to continuously form a weak but continuous airflow barrier on the front side of the wafer, providing basic positive pressure protection during the high-risk stage of wafer pick-up and drop-off, blocking possible contaminants in the environment. This "force-air coordination" lifting method significantly improves the stability and safety of the wafer pick-up and drop-off process.

[0135] In some embodiments, the control unit of the wafer clamping mechanism 100 performs the following complete process coordination process:

[0136] Wafer loading process: The robotic arm initially places the wafer above the wafer clamping mechanism 100, which is in the "lift-open" state. The control unit first commands the push rod 21 of the mechanical lifting device 20 to descend, so that the wafer is received and stabilized above the suspension air curtain generated by the pneumatic system. Subsequently, the clamping and positioning assembly 30 is activated, and the drive ring 32 rotates to move all the clamping pins 31 synchronously to the closed state, accurately positioning and gently clamping the wafer edge. After clamping, the control unit can fine-tune the pneumatic pressure as needed to ensure that the wafer reaches a precise target suspension height while clamped.

[0137] Cleaning process: The gas path system maintains a stable suspension and protective airflow, the mechanical lifting device 20 is in a lowered and locked state, and the clamping and positioning assembly 30 remains clamped. The drive unit 300 drives the entire clamping mechanism and the wafer to rotate at high speed, and the cleaning fluid supply unit 400 sprays the cleaning fluid. During this process, the control unit can dynamically fine-tune the airflow distribution based on sensor feedback to compensate for process disturbances.

[0138] Wafer unloading process: After cleaning, rotation stops. The control unit first instructs the clamping and positioning assembly 30 to move to the open state, completely releasing the lateral constraints on the wafer. Then, the aforementioned "mechanical lifting and airflow coordinated control" is activated to smoothly lift the wafer to a safe pick-up / drop-off height (e.g., 3-5mm). During this process, the air supply system can switch to a low-flow "maintenance mode" or gradually reduce the airflow according to the lifting height to ensure the wafer is stably lifted under the support of the push rod and to avoid sudden instability. After being lifted into position, the robotic arm safely enters and removes the wafer.

[0139] In this invention, to further improve reliability and prevent malfunctions, the mechanical lifting device 20 is equipped with a safety interlock logic. Before issuing a lifting command, the control unit first confirms that the clamping and positioning component 30 has completely released the wafer and that the main suspension airflow of the pneumatic system has been reduced to below a safe threshold. Simultaneously, a micro-force sensor or position sensor can be integrated at the top of each lifting rod 21 to monitor the contact status with the wafer in real time during the lifting process. If an abnormal lifting force or a lifting height below the preset value is detected, the control unit will immediately stop the lifting and issue an alarm to prevent mechanical damage caused by wafer jamming or displacement.

[0140] In addition, the present invention also provides a wafer cleaning apparatus 1000, the schematic diagram of which is shown below. Figure 11 As shown. The wafer cleaning apparatus 1000 includes:

[0141] The enclosure 200 provides a processing chamber for the cleaning and drying of the wafers;

[0142] like Figure 1 The wafer clamping mechanism 100 shown is disposed in the wafer processing chamber and is used to carry and protect the wafer; at the same time, a drive unit 300 is disposed below the wafer clamping mechanism 100, which can drive the wafer clamping mechanism 100 and the wafer on it to rotate around the axis.

[0143] The cleaning fluid supply unit 400 is used to spray cleaning fluid onto the back side of the wafer; specifically, the cleaning fluid supply unit 400 is a spray bar that sprays gas and / or liquid toward the wafer surface to remove contaminants from the wafer surface, thereby achieving cleaning and / or drying of the wafer.

[0144] The control system is communicatively connected to the control point pressing and driving unit 300 and the cleaning fluid supply unit 400 of the wafer clamping mechanism 100, and is used to coordinate the execution of the entire cleaning process and the collaborative control logic. This control system can integrate the functions of the control unit.

[0145] In some embodiments, the control system is configured to:

[0146] In response to the cleaning start command, the wafer clamping mechanism 100 is controlled to enter the cleaning mode;

[0147] In response to the wafer pick-up command, the wafer clamping mechanism 100 is switched to the wafer pick-up and drop-off mode, and the mechanical lifting device 20 is controlled to lift the wafer.

[0148] In this invention, the control system is further configured to:

[0149] In cleaning mode, the gas flow rate and pressure of the gas path system are adjusted according to preset process parameters to control the wafer's suspension height and the strength of the airflow barrier. The control system can also be linked with the upstream wafer measurement system to obtain precise thickness and warpage data of the wafer to be processed, and automatically optimize the cleaning suspension parameters and wafer pick-and-place coordination control parameters accordingly. This enables highly adaptable and highly reliable fully automated processing of wafers of different specifications, especially ultra-thin (e.g., <0.8mm) and high warpage wafers.

[0150] In summary, the wafer clamping mechanism of this invention deeply integrates non-contact airflow suspension protection and controllable mechanical lifting by introducing a "coordinated control logic of air flotation and mechanical lifting" led by a control unit. Its innovation lies not only in structural integration but also in the precise coordination of the two support modes in terms of timing and efficiency: during cleaning, it relies on a pure air flotation barrier for comprehensive protection; during pick-up and drop, it uses the coordination of "optimized flow maintenance airflow + mechanical lifting" to safely, smoothly, and without contamination solve the inherent problem of insufficient pick-up and drop space in traditional pure air flotation chucks, and overcomes the shortcomings of poor stability and adaptability of existing pure gas lifting solutions. Combined with multiple active sealing and airflow protection designs for the push rods and clamping pins, and dynamic airflow control capabilities suitable for ultra-thin / high warp wafers, a solution with ultra-high safety, excellent protection, and high adaptability is constructed for wafer back-side cleaning processes, significantly improving the reliability and yield of wafer back-side cleaning processes under advanced manufacturing processes.

[0151] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this application.

[0152] The above embodiments are only used to illustrate the embodiments of this application, and are not intended to limit the embodiments of this application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of this application. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of this application, and the patent protection scope of the embodiments of this application should be defined by the claims.

Claims

1. A wafer clamping mechanism for clamping and protecting a wafer during backside cleaning, characterized in that, include: Support disks are used to support the wafers to be processed. An air path system, located within the support disk, is used to provide airflow to the front side of the wafer, thereby suspending the wafer during the cleaning process through the Bernoulli effect and forming an airflow barrier that protects the front side of the wafer. A mechanical lifting device, integrated into the support plate, is used to lift the wafer to a height higher than the cleaning suspension height during wafer pick-up and drop-off. as well as, Control unit; The gas path system is configured in conjunction with the mechanical lifting device so that during the lifting action performed by the mechanical lifting device, the gas path system maintains a sustaining airflow that is lower than the flow rate of the cleaning and suspension airflow, so as to stabilize the wafer position and maintain the basic gas barrier during the lifting transition phase. The control unit is configured to execute the following cooperative control logic: In cleaning mode, the air circuit system is controlled to provide cleaning and suspended airflow, and the mechanical lifting device is controlled to be in a descending state; In wafer pick-and-place mode, the mechanical lifting device is activated to lift the wafer, and the gas path system is simultaneously switched to the maintaining gas flow.

2. The wafer clamping mechanism according to claim 1, characterized in that, The mechanical lifting device includes: Multiple push rods are movably inserted into the support disk, with their tips used to contact the removable area at the edge of the wafer; The drive chamber corresponding to each of the push rods is configured to selectively apply a force to the push rod, either keeping it in a descending state or lifting it upwards, by switching the air path.

3. The wafer clamping mechanism according to claim 2, characterized in that, The drive chamber includes an upper chamber and a lower chamber separated by the shaft of the push rod; The air passage system includes a first air intake passage and a second air intake passage; When the first air intake is opened and air is supplied to the upper chamber, the push rod is pressed into the lowered position; When the second air intake is opened and air is supplied to the lower chamber, the push rod is driven to the lifting position.

4. The wafer clamping mechanism according to claim 3, characterized in that, A dynamic sealing structure is provided between the top rod and the support plate. When the top rod is in the lowered position, the gas from the first air intake is configured to fill the mating gap between the top rod and the support plate, forming an airtight barrier.

5. The wafer clamping mechanism according to claim 2, characterized in that, The wafer clamping mechanism further includes a clamping and positioning component, which includes: Multiple clamping pins are rotatably disposed on the edge of the support plate; and The drive ring, which is linked to the clamping pin, is used to drive the clamping pin to rotate in order to clamp or release the wafer.

6. The wafer clamping mechanism according to claim 5, characterized in that, The wafer clamping mechanism further includes: An annular locking disc is located on the outer edge of the top of the support disc, and its outer side wall is provided with a wedge-shaped groove to block and guide the splashed cleaning fluid during the cleaning process.

7. The wafer clamping mechanism according to claim 6, characterized in that, The air passage system includes multiple sets of air vents: The first set of vents is located in the central area of ​​the support disk and is used to provide the main airflow that suspends the wafer; A second set of vents is arranged around the clamping pin to create localized airflow protection around the clamping pin, preventing cleaning fluid from seeping in along the clamping pin.

8. The wafer clamping mechanism according to claim 7, characterized in that, The second group of pores includes: The first aperture air hole is used to blow air into the annular groove of the clamping pin to form an upward airflow sealing wall that surrounds the clamping pin. The second aperture air hole is disposed on the locking plate and extends outward. Its aperture is smaller than that of the first aperture air hole, so that the airflow remains full in the annular groove area.

9. The wafer clamping mechanism according to claim 5, characterized in that, The drive ring is provided with toothed segments that mesh with the gear portion of the clamping pin. The drive ring is driven by a drive component to rotate or swing, thereby driving all the clamping pins to rotate synchronously.

10. The wafer clamping mechanism according to claim 7, characterized in that, The first group of pores is distributed in multiple rings on the support plate. The pores in different rings have different diameters and / or tilt angles to accommodate wafers of different thicknesses or warpages, so that their suspension height is uniform.

11. The wafer clamping mechanism according to claim 6, characterized in that, The inner edge of the locking disc is provided with a through placement hole for inserting the clamping pin; the inner sidewall of the placement hole includes a first arc segment, a second arc segment and a straight segment, which abut against different positions along the axial direction of the clamping pin to change the distance of the clamping pin relative to the center of the support disc, thereby achieving the clamping or release of the wafer.

12. The wafer clamping mechanism according to claim 11, characterized in that, The placement hole is a stepped hole, with the first arc segment located at the lower part of the placement hole, and the second arc segment and the straight segment located at the upper part of the placement hole.

13. The wafer clamping mechanism according to claim 12, characterized in that, The clamping pin includes a first cylindrical section, and an abutment post is offset above the first cylindrical section to abut against the edge of the wafer and clamp the wafer; the first cylindrical section and the abutment post are horizontally staggered to form a locking platform, which abuts against the stepped portion of the placement hole.

14. The wafer clamping mechanism according to claim 13, characterized in that, The outer diameter of the first cylindrical segment matches the size of the first arc segment, and the outer diameter of the abutting post matches the size of the second arc segment.

15. The wafer clamping mechanism according to claim 1, characterized in that, The flow rate of the maintaining airflow is configured to be 10% to 30% of the flow rate of the cleaning suspended airflow.

16. The wafer clamping mechanism according to claim 1, characterized in that, The mechanical lifting device is configured to lift the wafer to a pick-up and drop height of 3mm to 5mm.

17. A wafer cleaning apparatus, characterized in that, include: Enclosure to provide a wafer processing chamber; The wafer clamping mechanism as described in any one of claims 1 to 16 is disposed within the wafer processing chamber for carrying and protecting the wafer; A cleaning fluid supply unit is used to spray cleaning fluid onto the back side of the wafer; The control unit or an integrated control system is communicatively connected to the wafer clamping mechanism and the cleaning fluid supply unit to coordinate the execution of the collaborative control logic.

18. The wafer cleaning apparatus according to claim 17, characterized in that, The control system is also configured to: In cleaning mode, the gas flow rate and pressure of the gas path system are adjusted according to preset process parameters to control the suspension height of the wafer and the strength of the airflow barrier.

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