Circulating device

Abstract

The invention discloses a circulating device. The circulating device comprises a material barrel, an infusion pump and a return pipe, and the material barrel is filled with working fluid; the lower part, with a liquid inlet, of the infusion pump is inserted into the charging basket and is positioned below the liquid level; a liquid outlet is formed in the upper part of the infusion pump; one end of the backflow pipe is communicated with a liquid outlet of the infusion pump, the other end of the backflow pipe is connected with the side wall of the bottom of the material barrel and communicated with the interior of the material barrel, and at least one part of liquid pumped by the infusion pump enters the bottom of the material barrel through the backflow pipe. According to the circulating device, the pumped-out machining liquid flows into the bottom of the material barrel through the backflow pipe, so that the machining liquid in the bottom of the material barrel is in a flowing state, the probability that the machining liquid at the bottom of the material barrel settles is reduced, the bottom settling phenomenon is reduced, and the machining effect and the product machining yield are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor mask polishing liquid, and more particularly to a circulating device. BACKGROUND

[0002] In the polishing liquid tank, in order to stagger with the suction port of the suction pump, generally, the stirring blade is installed in the middle and lower part of the polishing liquid tank, and can stir most of the polishing liquid in the tank. However, the flow rate of the polishing liquid at the bottom is relatively low, and the liquid at the lowest position may even not flow for a long time. If the polishing liquid at the bottom of the tank settles for a long time, it will form a hardening, causing the concentration of the polishing liquid delivered to the polishing disc to decrease, affecting the polishing effect. Or the polishing liquid at the bottom of the tank will form agglomeration after settling, and the agglomeration will form large particles, which will scratch the surface of the glass substrate during polishing, affecting the yield of the glass substrate production. It is necessary to study the problem of settling of the polishing liquid at the bottom of the tank. SUMMARY

[0003] The purpose of the present application is to provide a circulating device to reduce the settling of the liquid at the bottom of the tank.

[0004] To achieve the above-mentioned purpose, the present application provides a circulating device, which comprises a tank, a suction pump and a backflow pipe, the tank is filled with processing liquid; the lower part of the suction pump with a liquid inlet is inserted into the tank and is below the liquid level, and the upper part of the suction pump is provided with a liquid outlet; one end of the backflow pipe is communicated with the liquid outlet of the suction pump, the other end of the backflow pipe is connected with the side wall of the bottom of the tank and the backflow pipe is communicated with the inside of the tank, and at least part of the liquid sucked out by the suction pump enters the bottom of the tank through the backflow pipe.

[0005] In an optional scheme, the circulating device further comprises a main stirring rod, the main stirring rod is arranged at the bottom of the inside of the tank and below the liquid inlet of the suction pump; the fixed end of the main stirring rod is hinged with the inner wall of the tank, and the rotation direction of the main stirring rod is the up-down direction, and the inlet of the backflow pipe at the bottom of the tank is below the hinged position of the main stirring rod and the inner wall of the tank, and the liquid outlet direction of the backflow pipe is the length direction of the main stirring rod.

[0006] In an optional scheme, the circulating device further comprises a slave stirring rod, the movable end of the main stirring rod is provided with a first magnet, one end of the slave stirring rod is provided with a second magnet, and the second magnet is below the first magnet; in the length direction of the main stirring rod, the polarities of the two ends of the first magnet are the same as those of the two ends of the second magnet.

[0007] In an optional scheme, the length of the first magnet ranges from 30mm to 40mm, and the length of the second magnet ranges from 30mm to 40mm.

[0008] In an optional scheme, the first magnet and the second magnet are both strip-shaped or columnar magnets.

[0009] In an optional solution, the circulating device further comprises stirring blades located in the hopper, and the active end of the main stirring rod is located below the stirring blades.

[0010] In an optional solution, the main stirring rod and the slave stirring rod are both hollow aluminum rod members.

[0011] In an optional solution, the outer surfaces of the main stirring rod and the slave stirring rod are provided with dispersing teeth distributed along the length direction.

[0012] In an optional solution, the liquid outlet of the pumping device is connected to the reflux pipe through a tee joint, the other interface of the tee joint is used to output the processing liquid, and the reflux pipe is provided with a valve with adjustable flow.

[0013] In an optional solution, the processing liquid is a polishing liquid.

[0014] The circulating device of the present application makes the pumped processing liquid flow into the bottom of the hopper through the reflux pipe, so that the processing liquid in the bottom of the hopper is in a flowing state, the probability of sedimentation of the processing liquid in the bottom of the hopper is reduced, the phenomenon of sedimentation in the bottom is reduced, and the processing effect and the product processing yield are improved. In addition, the circulating device of the present application further adds the main stirring rod and the slave stirring rod rotating upward and downward, under the combined action of the processing liquid thrust flowing into the reflux pipe, the suction force of the liquid inlet of the pumping device, and the mutual magnetic interaction force of the first magnet and the second magnet, the double rod members realize upward and downward stirring of the processing liquid in the bottom of the hopper, the stirring of the processing liquid in the bottom is strengthened, the dispersion effect is achieved, and the occurrence of processing liquid sedimentation is further prevented.

[0015] The above description is only a summary of the technical solutions of the present application. In order to better understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, some embodiments are listed below for detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Structure schematic diagram of the circulating device of at least one embodiment.

[0017] Figure 2 Schematic diagram of the main stirring rod and the slave stirring rod of at least one embodiment.

[0018] It should be noted that the products shown in the above views are appropriately reduced / enlarged to adapt to the size of the drawing and the clarity of the view, and the size of the products shown in the view is not limited. DETAILED DESCRIPTION

[0019] Polishing semiconductor photomasks requires polishing slurry, one of the requirements of which is particle dispersion—that is, the particles in the slurry must be well dispersed and avoid agglomeration to ensure polishing quality. Before being delivered to the polishing pad, the polishing slurry is temporarily stored in a tank awaiting extraction by a pump. The inventors discovered that even with continuous stirring of the slurry using a stirring blade in the tank, sedimentation always occurs at the bottom of the slurry.

[0020] To address the issue of polishing slurry settling at the bottom of the hopper, it's necessary to ensure its flow. Adding a horizontal stirring blade below the existing lower-middle-position stirring blade would agitate the bottom horizontally, but not vertically, resulting in stratified agitation and failing to achieve adequate mixing at the bottom. Designing a vertically rotating stirring blade would require a drive motor and transmission mechanism at the bottom, and ensuring the blade's smooth insertion would easily lead to slurry leakage, making it impractical. To achieve thorough mixing at the bottom of the hopper, the inventors researched creating a multi-directional flow of liquid below the stirring blade through liquid backflow and vertical stirring with a stirring rod, thus preventing polishing slurry settling.

[0021] The technical solutions of 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. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application.

[0022] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. 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.

[0025] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0026] One or more embodiments of this application are a recycling device, the specific structure of which is as follows: Figure 1 and Figure 2 As shown. Figure 1 As shown, the circulation device includes a material tank 10, a liquid pump 20, and a return pipe 24. The material tank 10 contains processing fluid. In at least one embodiment, the processing fluid is a polishing fluid with a density ranging from 1.20 to 1.28 g / cm³ and a viscosity ranging from 3 to 6 mPa·s. Figure 1As shown, the lower part of the pump 20, with a liquid inlet 21, is inserted into the tank 10 and positioned below the liquid surface. The upper part of the pump 20 has a liquid outlet 22. One end of the return pipe 24 is connected to the liquid outlet 22 of the pump 20, and the other end of the return pipe 24 is connected to the bottom side wall of the tank 10 and connects to the interior of the tank 10. When the pump 20 is operating, at least a portion of the processing fluid drawn out by the pump 20 enters the bottom of the tank 10 through the return pipe 24, accelerating the flow of the processing fluid at the bottom of the tank 10. Therefore, the circulation device, through the return pipe 24, directs the drawn processing fluid into the bottom of the tank 10, keeping the processing fluid at the bottom of the tank 10 in a flowing state. This reduces the probability of sedimentation at the bottom of the tank 10, thus reducing bottom sedimentation and improving the polishing effect and yield of the glass substrate polishing process.

[0027] In at least one embodiment, such as Figure 1 As shown, the liquid outlet of the pump 20 is connected to the return pipe 24 via a T-junction 23, and the remaining port of the T-junction 23 is used to output the processing fluid to the processing station (e.g., a polishing pad). In at least one embodiment, a filter 26 and a flow meter 27 are connected between the remaining port of the T-junction 23 and the processing station. The filter 26 is used to filter out large particles and small impurities in the processing fluid to avoid excessive large particles and impurities in the processing fluid, which could lead to poor processing results or damage to the workpiece. The flow meter 27 is used to detect the real-time flow rate to the processing station, allowing the operator to adjust the real-time power of the pump 20 in real time based on the real-time flow rate and processing conditions.

[0028] In at least one embodiment, such as Figure 1 As shown, the reflux pipe 24 is equipped with an adjustable flow rate valve 25. The reflux flow rate needs to be controlled within a suitable range. If the reflux flow rate is too high, it will reduce the amount of processing fluid flowing into the processing station, thus failing to guarantee the processing effect. If the reflux flow rate is too low, the flow rate of the processing fluid at the bottom of the tank 10 will be insufficient to reduce sedimentation. Therefore, the reflux processing fluid flow rate must be within the power range of the pump 20 to ensure that enough processing fluid is delivered to the processing station, while also ensuring that the processing fluid at the bottom of the tank 10 has a sufficient flow rate. In at least one embodiment, the flow rate regulating valve 25 of the reflux pipe 24 is a manually adjustable valve, which allows the operator to manually adjust the opening and closing degree of the valve 25 according to the actual situation and personal experience. In addition, different viscosities of processing fluids have different flow rate requirements. For example, high-viscosity processing fluids require a slightly higher flow rate to generate a sufficient flow rate, while low-viscosity processing fluids require a slightly lower flow rate to avoid excessively fast flow rates.

[0029] In at least one embodiment, to determine the flow rate of the processing fluid at the bottom of the material tank 10, a flow meter (not shown) can be installed inside the bottom of the material tank 10. Simultaneously, the flow regulating valve 25 of the return pipe 24 is an electrically controlled valve. The valve 25 and the flow meter are electrically connected to a main control unit (not shown). The main control unit receives the real-time flow rate from the flow meter and, based on the target liquid flow rate and the established and stored mapping relationship between liquid flow rate and valve 25 opening degree, controls the valve 25 to adjust to the corresponding opening degree, thereby achieving automated flow control and reducing manual intervention. Furthermore, in other embodiments, the main control unit is also electrically connected to a pump 24 and a flow meter 27. When the real-time flow rate to the processing station received by the main control unit from the flow meter 27 is lower than a set value, the main control unit controls the pump 20 to increase its power to improve the real-time flow rate.

[0030] In at least one embodiment, such as Figure 1 As shown, a liquid level gauge 33 is also inserted into the material tank 10. The liquid level gauge 33 is used to monitor the liquid level in the material tank 10. If it is lower than the set threshold, the operator will be reminded to add liquid through an audible and visual alarm to avoid affecting the processing effect.

[0031] In at least one embodiment, such as Figure 1 As shown, a drain pipe 60 is provided on one side of the bottom surface of the material tank 10. The drain pipe 60 is equipped with a manual valve. The drain pipe 60 is mainly used to drain the liquid inside the material tank 10 for cleaning or equipment maintenance.

[0032] In at least one embodiment, such as Figure 1 As shown, the circulation device also includes a rotating stirring blade 31, which is located inside the material tank 10 and its height is lower than the liquid inlet 21 of the pump 20. The stirring blade 31 is driven to rotate by a stirring pump 32 above the material tank 10. The stirring blade 31 stirs the processing fluid in the material tank 10, and the liquid near the stirring blade 31 flows outward from the stirring blade 31.

[0033] In at least one embodiment, combined Figure 1 and Figure 2As shown, the circulation device also includes a main stirring rod 40, which is located at the bottom inside the material tank 10 and below the liquid inlet 21 of the pump 20. The fixed end of the main stirring rod 40 is hinged to the inner wall of the material tank 10, and the main stirring rod 40 rotates in the up-down direction. The inlet 241 of the return pipe 24 at the bottom of the material tank 10 is located below the hinge point 401 between the main stirring rod 40 and the inner wall of the material tank 10, and the liquid outlet direction of the return pipe 24 is horizontal. The processing fluid flowing into the bottom of the material tank 10 through the return pipe 24 will generate an upward pushing force on the main stirring rod 40, and combined with the suction force of the liquid inlet 21 of the pump 20, it causes the main stirring rod 40 to rotate upward. The hinge of the main stirring rod 40 to the inner wall of the material tank 10 prevents the main stirring rod 40 from being sucked into the liquid inlet 21 of the pump 20.

[0034] Furthermore, in at least one embodiment, a limiting surface 402 is provided at the hinge 401 between the main stirring rod 40 and the inner wall of the hopper 10, such as... Figure 2 As shown, the limiting surface 402 is used to limit the maximum upward rotation angle of the main stirring rod 40, so as to prevent the main stirring rod 40 from rotating too much upward and coming into contact with the liquid pump 20 or the stirring blade 31.

[0035] Furthermore, in at least one embodiment, the main stirring rod 40 is a hollow aluminum rod to reduce its weight and prevent it from being too heavy and lacking sufficient power to drive its upward rotation. Additionally, since the processing fluid may be corrosive, the surface of the main stirring rod 40 is treated with anti-corrosion measures, such as coating it with polytetrafluoroethylene (PTFE). Similarly, the hinge structure between the main stirring rod 40 and the inner wall of the container 10 is also treated with anti-corrosion measures or made of 316L stainless steel.

[0036] Furthermore, in at least one embodiment, such as Figure 2 As shown, the outer surface of the main stirring rod 40 is provided with dispersing teeth 42 distributed along its length. The dispersing teeth 42 help to enhance the particle breaking effect. For example, when used to stir polishing fluid containing nano- or micro-abrasives, they can effectively prevent particle agglomeration and achieve better stirring and dispersion effects. Figure 2 The design of the dispersion teeth 42 is shown only as an example and is not intended to limit the shape, size, number, or distribution of the dispersion teeth 42.

[0037] In at least one embodiment, combined Figure 1 and Figure 2As shown, the circulation device also includes a secondary stirring rod 50. A first magnet 41 is provided at the movable end of the main stirring rod 40, and the first magnet 41 can be fixed to the main stirring rod 40 by means of tight fit, threaded connection, etc. Furthermore, the outer surface of the first magnet 41 of the main stirring rod 40 can also be provided with dispersing teeth. Simultaneously, a second magnet 51 is provided at one end of the secondary stirring rod 50, and the second magnet 51 can be fixed to the secondary stirring rod 50 by means of tight fit, threaded connection, etc. The length of the main stirring rod 40 (including the length of the first magnet 41) is not less than half the inner diameter of the material container 10, and the length of the secondary stirring rod 50 (including the length of the second magnet 51) is 40%-50% of the inner diameter of the material container 10.

[0038] The second magnet 51 is located below the first magnet 41, and its height from the stirring rod 10 is slightly lower than that of the main stirring rod 40. In specific implementations, both the first magnet 41 and the second magnet 51 are bar or columnar magnets, and their lengths are both between 30mm and 40mm. Along the length of the main stirring rod 40, the polarities at both ends of the first magnet 41 and the second magnet 51 are the same. Figure 2 As shown, one end of the first magnet 41 is the N pole, and the corresponding end of the second magnet 51 is also the N pole; the other end of the first magnet 41 is the S pole, and the other end of the second magnet 51 is also the S pole. Both the first magnet 41 and the second magnet 51 are relatively short, therefore, there is both repulsive and attractive force between them. The processing fluid flows through the space between the first magnet 41 and the second magnet 51. The processing fluid has a certain viscosity, and it exerts a certain viscous resistance on the first magnet 41 and the second magnet 51, thus maintaining a certain relative distance between them. In specific implementations, the first magnet 41 and the second magnet 51 are made of strong magnetic materials, such as neodymium iron boron, and their surfaces are treated with anti-corrosion measures, such as nickel plating.

[0039] In at least one embodiment, such as Figure 1As shown, the movable end of the main stirring rod 40 is located below the stirring blade 31, and the secondary stirring rod 50 is also located below the stirring blade 31. The processing fluid flowing into the bottom of the feed tank 10 through the return pipe 24 will also exert an upward pushing force on the main stirring rod 40 and the secondary stirring rod 50. Combined with the suction force of the liquid inlet 21 of the liquid pump 20, the main stirring rod 40 will rotate upward, and the secondary stirring rod 50 will also be forced to move upward. Since there is both attraction and repulsion between the first magnet 41 and the second magnet 51, when the main stirring rod 40 rotates upward, the first magnet 41 has a certain pulling effect on the second magnet 51, but the two will not get too close. Therefore, the second magnet 51 of the secondary stirring rod 50 will maintain a certain distance from the first magnet 41 of the main stirring rod 40. When the main stirring rod 40 and the secondary stirring rod 50 float to near the area below the stirring blade 31, the pushing force of the processing fluid flowing into the return pipe 24 on the main stirring rod 40 and the secondary stirring rod 50 decreases. The processing fluid below the stirring blade 31 exerts a certain downward pushing force on the main stirring rod 40 and the secondary stirring rod 50. Combined with the weight of the main stirring rod 40 and the secondary stirring rod 50, the main stirring rod 40 will rotate downward at a certain angle, and the secondary stirring rod 50 will also move downward a certain distance. During the descent, the pushing force of the processing fluid flowing into the return pipe 24 on the main stirring rod 40 and the secondary stirring rod 50 gradually increases, eventually pushing the main stirring rod 40 and the secondary stirring rod 50 upward again. This results in the processing fluid at the bottom of the material tank 10 continuously floating and sinking, thereby achieving the effect of stirring the processing fluid up and down.

[0040] Furthermore, in at least one embodiment, the stirring rod 50 is a hollow aluminum rod to reduce its weight and prevent it from becoming too heavy to suspend. Additionally, since the processing fluid may be corrosive, the surface of the stirring rod 50 is treated with an anti-corrosion coating, such as a polytetrafluoroethylene coating.

[0041] Furthermore, in at least one embodiment, such as Figure 2 As shown, the stirring rod 50 has dispersion teeth 52 distributed along its length on its outer surface. The dispersion teeth 52 help to enhance the particle breaking effect. For example, when used to stir polishing fluid containing nano or micro abrasives, they can effectively prevent particle agglomeration and achieve better stirring and dispersion effects. Figure 2 The design of the dispersing teeth 52 is shown only as an example and is not intended to limit the shape, size, number, or distribution of the dispersing teeth 52. Furthermore, dispersing teeth may also be provided on the exterior of the second magnet 51 of the stirring rod 50.

[0042] In specific operation, the main stirring rod 40 and the driven stirring rod 50 are first placed vertically, with the first magnet 41 and the second magnet 51 corresponding vertically. The N pole of the first magnet 41 corresponds to the N pole of the second magnet 51, and the S pole of the first magnet 41 corresponds to the S pole of the second magnet 51. Then, the refluxed processing fluid is introduced to drive the main stirring rod 40 and the driven stirring rod 50 to move. The flow rate of the refluxed processing fluid is gradually adjusted to regulate the distance between the first magnet 41 and the second magnet 51, so that they remain relatively stable. Finally, the main stirring rod 40 and the driven stirring rod 50 repeatedly float and sink at the bottom of the material tank, realizing the function of stirring the bottom of the material tank 10.

[0043] Therefore, it can be seen that the circulation device of at least one embodiment also incorporates a main stirring rod 40 that rotates up and down. Under the combined action of the thrust of the processing fluid flowing in from the return pipe 24, the suction force of the liquid inlet 21 of the pump 20, the weight of the rod itself, and the mutual magnetic force between the rods, the processing fluid is stirred up and down at the bottom of the material tank 10 by the two rods, which strengthens the stirring of the processing fluid at the bottom and makes the dispersion effect better. The processing fluid is drawn out by the pump 20 and transported to the processing station, which is beneficial to improving the processing effect.

[0044] The circulation device of this application has the following advantages: 1. The existing liquid pump 20 in the material tank 10 is used to realize the circulation of the processing liquid, without the need to add an additional circulation pump, which helps to better control equipment costs.

[0045] 2. The processing fluid returned from the pump 20 and the return pipe 24 is used as the driving source. On the one hand, it drives the processing fluid in the bottom of the material tank 10 to flow faster, and on the other hand, it drives the main stirring rod 40 and the secondary stirring rod 50 to move up and down. There is no need to set up additional driving components such as driving motors. The structure is simple and the cost is low. It also reduces the leakage risk that may be caused by setting up additional driving mechanisms.

[0046] 3. The main stirring rod 40 and the secondary stirring rod 50 float and submerge in the bottom area of ​​the material tank 10 to achieve up-and-down stirring, which increases the stirring force of the processing liquid in the bottom area and improves the dispersion effect of the processing liquid. The stirred and dispersed processing liquid is then pumped into the processing station, which is beneficial to improving the processing effect.

[0047] 4. During the up-and-down movement of the main stirring rod 40 and the secondary stirring rod 50, the processing fluid exerts a driving force on the rod body. At the same time, the magnetic force between the first magnet 41 and the second magnet 51 also plays a mutual driving role, which is equivalent to "dual power". This reduces the probability of a single stirring rod getting stuck due to excessive viscous resistance and is more suitable for processing fluids with high viscosity and containing small particles, such as resin and paste polishing fluid.

[0048] 5. The main stirring rod 40 is hinged to the side wall of the material tank 10. The backflowing processing fluid pushes the main stirring rod 40 to rotate up and down. There is a non-contact torque transmission between the first magnet 41 and the second magnet 51, which causes the stirring rod 50 to follow the movement. At the same time, the stirring rod 50 is also subjected to the multi-directional force of the multi-directional flow of processing fluid in the bottom of the material tank 10, which causes a slight lateral movement, thereby stirring the bottom, edge and other hard-to-cover areas of the material tank 10.

[0049] The above examples are merely illustrative of the technical content of this application to facilitate reader understanding, but do not imply that the implementation methods of this application are limited to these. Any technical extensions or re-creations made based on this application are protected by this application. The scope of protection of this application is determined by the claims.

Claims

1. A circulation device, characterized in that, It includes: A material tank containing processing fluid; A liquid pump, wherein the lower part of the liquid pump with a liquid inlet is inserted into the material tank and is below the liquid surface, and the upper part of the liquid pump has a liquid outlet; A return pipe is provided, with one end connected to the liquid outlet of the pump and the other end connected to the bottom side wall of the container and the inside of the container. At least a portion of the liquid pumped by the pump enters the bottom of the container through the return pipe.

2. The circulation device as described in claim 1, characterized in that, The circulation device also includes a main stirring rod, which is located at the bottom of the material tank and below the liquid inlet of the pump. The fixed end of the main stirring rod is hinged to the inner wall of the material tank and the main stirring rod rotates in the up-down direction. The inlet of the return pipe at the bottom of the material tank is located below the hinge point between the main stirring rod and the inner wall of the material tank.

3. The circulation device as described in claim 2, characterized in that, The circulation device also includes a secondary stirring rod, the movable end of the main stirring rod is provided with a first magnet, and one end of the secondary stirring rod is provided with a second magnet, the second magnet being located below the first magnet; along the length of the main stirring rod, the polarities of the two ends of the first magnet and the two ends of the second magnet are the same.

4. The circulation device as described in claim 3, characterized in that, The length of the first magnet is 30mm-40mm, and the length of the second magnet is 30mm-40mm.

5. The circulation device as described in claim 3, characterized in that, Both the first magnet and the second magnet are bar or columnar magnets.

6. The circulation device as described in claim 3, characterized in that, The circulation device also includes stirring blades, which are located inside the material tank. The movable end of the main stirring rod is located below the stirring blades, and the secondary stirring rod is located below the stirring blades.

7. The circulation device as described in claim 3, characterized in that, Both the main stirring rod and the slave stirring rod are hollow aluminum rods.

8. The circulation device as described in claim 3, characterized in that, The main stirring rod and the secondary stirring rod are provided with dispersion teeth distributed along the length direction on their outer surfaces.

9. The circulation device as claimed in claim 1, characterized in that, The liquid outlet of the pump is connected to the return pipe via a tee, and the other port of the tee is used to output the processing fluid. The return pipe is equipped with a valve with adjustable flow rate.

10. The circulation device according to any one of claims 1-9, characterized in that, The processing fluid is a polishing fluid.

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