A real-time pressure adjustment system for a silicon wafer polishing head

Abstract

The application discloses a silicon wafer polishing head pressure real-time adjusting system and relates to the technical field of silicon wafer polishing. The system comprises a shell, which is installed at the output end of a polishing device and has a rotary joint installed on the upper end face; a partition disc, which is fixed in the shell and separates the interior of the shell into a liquid storage bin and a cooling bin; a fixed disc, which is fixed in the cooling bin; a plurality of micro pump valves, which are fixed on the upper end face of the fixed disc and are connected with the liquid storage bin through pipelines; a controller, which is fixed on the fixed disc and is electrically connected with the micro pump valves; a partition adjusting assembly, which is fixed on the lower end face of the cooling bin; a limiting ring, which is vertically slidably arranged on the lower end face of the shell and is connected with the micro pump valves through an adjusting pipe; and a silicon wafer, which is installed on the lower end face of the partition adjusting assembly and is located in the limiting ring.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon wafer polishing, and particularly relates to a silicon wafer polishing head pressure real-time adjusting system. BACKGROUND

[0002] Chemical mechanical polishing (CMP) is a key process step for global planarization in semiconductor manufacturing. The silicon wafer polishing head is responsible for carrying the silicon wafer during polishing and applying controllable pressure to the back of the silicon wafer. Traditional polishing head pressure adjusting methods mainly include:

[0003] 1. Air bag type: one or more inflatable air bags are used to apply overall or zoned pressure through air pressure changes. Disadvantages: poor pressure distribution continuity (obvious zoned boundary effect), slow response speed (caused by gas compressibility), pressure accuracy affected by nonlinear deformation of air bag material, and difficult to achieve high-precision independent control of small areas.

[0004] 2. Rigid zoned type: the lower plate of the polishing head is divided into multiple rigid zones, and the height and pressure of each zone are adjusted by independent mechanical or pneumatic devices. Disadvantages: strong mechanical coupling between zones, adjusting one zone will significantly affect the pressure of adjacent zones; poor adaptability to silicon wafer warping or uneven thickness, easy to cause local over-polishing or under-polishing, complex structure, and difficult to maintain.

[0005] 3. Single membrane type: a whole piece of flexible membrane is used to cover the back of the silicon wafer, and the overall pressure is controlled by the pressure of the back pressure chamber. Disadvantages: unable to achieve independent pressure control of different areas of the silicon wafer surface.

[0006] In view of the above problems, the present application provides a silicon wafer polishing head pressure real-time adjusting system to solve the above problems. SUMMARY

[0007] To achieve the above purpose, the present application provides the following technical scheme: a silicon wafer polishing head pressure real-time adjusting system, comprising:

[0008] A housing is installed at the output end of a polishing device, and a rotary joint is installed on the upper end face thereof;

[0009] A partition disc is fixed inside the housing and divides the inside of the housing into a liquid storage compartment and a cooling compartment from top to bottom, and the liquid storage compartment is in communication with an external liquid supply device through the rotary joint;

[0010] A fixed disc is fixed in the cooling compartment;

[0011] A plurality of micro pump valves are fixed on the upper end face of the fixed disc and are in communication with the liquid storage compartment through pipelines;

[0012] A controller is fixed on the fixed disc and is electrically connected with the plurality of micro pump valves;

[0013] partition adjusting assembly, fixed on the lower end surface of the cooling chamber;

[0014] limiting ring, vertically slidingly arranged on the lower end surface of the shell, and communicating with one of the micro-pump valves through an adjusting tube;

[0015] silicon wafer, mounted on the lower end surface of the partition adjusting assembly and located within the limiting ring.

[0016] Further, preferably, a plurality of cooling holes are obliquely arranged on the outer wall of the shell corresponding to the cooling chamber, and the plurality of cooling holes are obliquely arranged towards the fixed disc along the axial direction of the cooling chamber, and the plurality of cooling holes are obliquely arranged towards the rotation direction of the shell along the radial direction of the cooling chamber.

[0017] Further, preferably, the partition adjusting assembly comprises:

[0018] base plate, fixed on the lower end surface of the cooling chamber, and a conversion chamber is arranged on the side of the base plate away from the cooling chamber;

[0019] cavity, configured as a plurality of cavities, each fixed in the conversion chamber, and the cavities are in communication with the plurality of micro-pump valves through a hose;

[0020] sealing film, fixed on the side of the base plate away from the cooling chamber, and the sealing film seals and isolates the plurality of cavities;

[0021] flexible film, fixed on the side of the sealing film away from the base plate;

[0022] conversion assembly, configured as a plurality of conversion assemblies, each fixed in the conversion chamber and located between the plurality of cavities;

[0023] suction pipe, fixed in the cavity, one end of the suction pipe in communication with the hose, and the other end of the suction pipe close to the sealing film without contacting the sealing film.

[0024] Further, preferably, a pressure sensor is mounted on the hose connected to the plurality of cavities, a vacuum suction hole is arranged on the base plate between the plurality of cavities, and the vacuum suction hole is connected to a vacuum pump fixed on the fixed disc.

[0025] Further, preferably, the initial shape of the cavity is a regular hexagon, and the cavity is made of flexible material, and the plurality of conversion assemblies are respectively located at the vertices of the regular hexagon and the middle positions of the sides.

[0026] Further, preferably, the conversion assembly comprises:

[0027] first conversion assembly, configured as six first conversion assemblies, fixed at the vertex positions of the cavity;

[0028] The second conversion assembly is configured as six, and is fixed at the middle position of the side of the cavity.

[0029] Further, preferably, the first conversion assembly comprises:

[0030] The first fixed pipe is communicated with a suction pump through a first air inlet pipe, and the suction pump is fixed in the cooling bin.

[0031] The first fixed plate is configured as three, is fixed uniformly at the outer wall of the first fixed pipe in a circle, and is communicated with the inside of the first fixed pipe.

[0032] The first extrusion plate is slidably arranged on the first fixed plate through a plurality of first pistons.

[0033] The flexible column is fixed at one end of the first extrusion plate away from the first piston, and is fixedly connected with the vertex of the cavity.

[0034] Further, preferably, the second conversion assembly comprises:

[0035] The second fixed pipe is communicated with a suction pump through a second air inlet pipe, and the suction pump is fixed in the cooling bin.

[0036] The second fixed plate is configured as two, is fixed symmetrically at the outer wall of the second fixed pipe, and is communicated with the inside of the second fixed pipe.

[0037] The second extrusion plate is slidably arranged on the second fixed plate through a plurality of second pistons, and the second extrusion plate is fixedly connected with the middle position of the side of the cavity.

[0038] Further, preferably, when the conversion assembly converts the cavity, the vertex position of the cavity is first extruded through the first conversion assembly, at this time, the second conversion assembly is in a static state, so that the regular hexagonal cavity is converted into a circular shape, and then the size of the circular cavity needs to be adjusted, at this time, the first conversion assembly and the second conversion assembly are synchronously driven.

[0039] Compared with the prior art, the present application provides a silicon wafer polishing head pressure real-time adjustment system, which has the following beneficial effects:

[0040] In the present application, a plurality of independent cavities are connected through respective micro-pump valves and hoses, and the controller can independently adjust the liquid pressure of each cavity, so that the flexible membrane uniformly and flexibly transmits the cavity pressure to different areas on the back of the silicon wafer, reduces the obvious partition boundary effect, and significantly reduces the pressure influence of adjacent partitions. Through the inclined cooling hole (axially towards the fixed disc, radially in accordance with the rotation direction), the shell can utilize the centrifugal force and airflow inertia generated by rotation to guide and concentrate the airflow to the key heating components when rotating, thereby greatly improving the heat dissipation efficiency.

[0041] The shape of the cavity can be converted by the conversion assembly, so that the initial regular hexagon of the cavity is converted into a circle. When the cavity is an initial regular hexagon, the regular hexagonal honeycomb can provide the highest density of pressure partitions and the optimal space filling efficiency (coverage), achieve the most refined local area pressure control, and is particularly suitable for applications with extremely high flatness requirements. When it is a circle, the pressure uniformity is optimal, there is no stress concentration point, and the circular stress distribution is uniform, which is strong in fatigue resistance and can improve the service life of the flexible film under cyclic pressure. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a schematic view of the overall structure of a silicon wafer polishing head pressure real-time adjustment system;

[0043] Figure 2 It is Figure 1 It is an enlarged structure schematic view of A in the middle;

[0044] Figure 3 It is a schematic view of the structure of a partition adjustment assembly of a silicon wafer polishing head pressure real-time adjustment system;

[0045] Figure 4 It is a schematic view of the distribution structure of a conversion assembly of a silicon wafer polishing head pressure real-time adjustment system;

[0046] Figure 5 It is a schematic view of the structure of a first conversion assembly of a silicon wafer polishing head pressure real-time adjustment system;

[0047] Figure 6 It is a schematic view of the structure of a second conversion assembly of a silicon wafer polishing head pressure real-time adjustment system;

[0048] Figure 7 It is a schematic view of the conversion state of a silicon wafer polishing head pressure real-time adjustment system;

[0049] In the figure: 1, housing; 2, partition disc; 3, liquid storage bin; 4, cooling bin; 5, fixed disc; 6, micro pump valve; 7, controller; 8, partition adjustment assembly; 9, limiting ring; 10, silicon wafer; 11, cooling hole; 81, base plate; 82, cavity; 83, sealing film; 84, flexible film; 85, conversion assembly; 86, suction pipe; 851, first conversion assembly; 852, second conversion assembly; 8511, first fixed pipe; 8512, first air inlet pipe; 8513, first piston; 8514, first extrusion plate; 8515, flexible column; 8521, second fixed pipe; 8522, second air inlet pipe; 8523, second piston; 8524, second extrusion plate; 91, adjustment pipe. DETAILED DESCRIPTION

[0050] ReferenceFigures 1-7 The application provides a technical scheme: a silicon wafer polishing head pressure real-time adjusting system, comprising:

[0051] A shell 1 is installed at the output end of a polishing device, and a rotating joint is installed on the upper end face of the shell 1;

[0052] A partition disc 2 is fixed in the shell 1, and divides the inside of the shell 1 into a liquid storage bin 3 and a cooling bin 4 from top to bottom, and the liquid storage bin 3 is communicated with an external liquid supply device through the rotating joint;

[0053] A fixed disc 5 is fixed in the cooling bin 4;

[0054] A plurality of micro pump valves 6 are arranged, and are fixed on the upper end face of the fixed disc 5 and communicated with the liquid storage bin 3 through pipelines;

[0055] A controller 7 is fixed on the fixed disc 5 and electrically connected with the plurality of micro pump valves 6;

[0056] A partition adjusting assembly 8 is fixed on the lower end face of the cooling bin 4;

[0057] A limiting ring 9 is vertically slidably arranged on the lower end face of the shell 1 and communicated with one of the micro pump valves 6 through an adjusting pipe 91;

[0058] A silicon wafer 10 is installed on the lower end face of the partition adjusting assembly 8 and located in the limiting ring 9.

[0059] When the silicon wafer 10 is polished, the back surface of the silicon wafer 10 is installed on the partition adjusting assembly 8 through vacuum adsorption, hydraulic oil is injected into the liquid storage bin 3, and the pressure of the partition adjusting assembly 8 is stabilized to an initial set value ± 0.05 psi.

[0060] It should be noted that the hydraulic oil is preferably low-viscosity hydraulic oil, which has incompressibility, so as to realize millisecond-level and high-precision control of the hydraulic pressure.

[0061] And the initial pressure of the limiting ring 9 is higher than the back pressure of the silicon wafer 10, so as to prevent the silicon wafer 10 from slipping.

[0062] In the embodiment, a plurality of cooling holes 11 are obliquely arranged on the outer wall of the shell 1 and corresponding to the cooling bin 4, the plurality of cooling holes 11 are all inclined to the fixed disc 5 along the axial direction of the cooling bin 4, and the plurality of cooling holes 11 are all inclined to the rotation direction of the shell 1 along the radial direction of the cooling bin 4.

[0063] That is, through the inclined cooling hole 11, and its axial direction towards the fixed disc 5, radial compliance shell 1 rotation direction, can make the shell 1 in the rotation using the centrifugal force generated by rotation and airflow inertia, to the key heat components of the airflow guide concentrated blowing, greatly improve the heat dissipation efficiency.

[0064] In the present embodiment, the partition adjustment assembly 8 comprises:

[0065] The base plate 81 is fixed at the lower end surface of the cooling chamber 4, and a conversion chamber is opened on the side away from the cooling chamber 4;

[0066] The cavity 82 is configured as a plurality of cavities, each fixed in the conversion chamber, and the cavity 82 is communicated with a plurality of micro-pump valves 6 through a hose;

[0067] The sealing film 83 is fixed on the side of the base plate 81 away from the cooling chamber 4, and the sealing film 83 seals and isolates a plurality of cavities 82;

[0068] The flexible film 84 is fixed on the side of the sealing film 83 away from the base plate 81;

[0069] The conversion assembly 85 is configured as a plurality of conversion assemblies, each fixed in the conversion chamber and located between a plurality of cavities 82;

[0070] The suction pipe 86 is fixed in the cavity 82, one end of which is communicated with the hose, and the other end is close to the sealing film 83 without contacting the sealing film 83.

[0071] Optionally, a thin and uniform pressure transmission medium layer (such as hydrogel, low viscosity silicone oil layer or specially designed elastic pad) can be added between the flexible film 84 and the back of the silicon wafer 10 to improve the continuity of pressure distribution and protect the back of the silicon wafer 10.

[0072] In addition, the flexible film 84 is combined with a plurality of independent and dense cavities 82 to replace the traditional air bag or rigid partition, the flexible film 84 provides uniform contact and flexible adaptation, and the plurality of independent cavities 82 provide a high-resolution pressure regulation unit with physical isolation, thereby improving the accuracy of partition control.

[0073] Optionally, a pressure sensor is installed on the hose connected to a plurality of cavities 82, and a vacuum suction hole is opened on the base plate 81 between a plurality of cavities 82, and the vacuum suction hole is connected to a vacuum pump fixed on the fixed disc 5.

[0074] When the conversion assembly 85 adjusts the shape of the cavity 82, the cavity 82 is not in a vacuum state at this time, that is, the cavity 82 can slide relative to the substrate 81 and the sealing film 83 at this time, facilitating shape conversion. After the conversion is completed, the sealing film 83 is pressed against the cavity 82 by vacuumizing, thereby sealing the cavity 82. It should be noted that the pressure of vacuumizing is greater than the pressure of the hydraulic oil on the sealing film 83, so as to avoid the leakage of the hydraulic oil.

[0075] In addition, when the silicon wafer 10 is locally uneven, the pressure value of the corresponding pressure sensor increases or decreases at this time. At this time, the micro pump valve 6 injects or extracts hydraulic oil into or from the cavity 82, thereby performing real-time partition adjustment and improving the response speed of the adjustment.

[0076] As a preferred embodiment, the initial shape of the cavity 82 is a regular hexagon, and the cavity 82 is made of flexible material. The conversion assemblies 85 are respectively located at the vertices of the regular hexagon and the middle positions of the edges.

[0077] It should be noted that the plurality of cavities 82 are arranged in a honeycomb shape.

[0078] That is, the regular hexagonal honeycomb shape of the cavity 82 can provide the highest density of pressure partitions and the optimal space filling efficiency (coverage rate), realize the most fine local area pressure control, and is particularly suitable for applications with extremely high flatness requirements. In addition, the honeycomb arrangement can improve the deformation resistance and the edge adaptability, and the regular hexagonal deformable splicing matches the edge curvature of the silicon wafer 10, thereby improving the coverage rate.

[0079] As a preferred embodiment, the conversion assembly 85 includes:

[0080] The first conversion assembly 851 is configured as six and is fixed at the vertex position of the cavity 82.

[0081] The second conversion assembly 852 is configured as six and is fixed at the middle position of the edge of the cavity 82.

[0082] The first conversion assembly 851 includes:

[0083] The first fixed pipe 8511 is communicated with the suction pump through the first air inlet pipe 8512, and the suction pump is fixed in the cooling bin 4.

[0084] The first fixed plate is configured as three and is circumferentially and uniformly fixed to the outer wall of the first fixed pipe 8511 and is communicated with the inside of the first fixed pipe 8511.

[0085] The first extrusion plate 8514 is slidably provided on the first fixed plate by a plurality of first pistons 8513.

[0086] A flexible column 8515 is fixed at one end of the first extrusion plate 8514 away from the first piston 8513 and is fixedly connected to the vertex of the cavity 82.

[0087] When the shape of the cavity 82 needs to be converted, gas is injected into the first fixed tube 8511 through the first gas inlet tube 8512, so that the first piston 8513 pushes the first extrusion plate 8514 and the flexible column 8515 to slide, thereby extruding the vertex position of the cavity 82 and converting the cavity 82 into a circular shape. The flexible column 8515 can provide flexible support to the vertex, thereby reducing the formation of sharp corners at the vertex. Figure 7 F is the direction of the applied force.

[0088] As a preferred embodiment, the second conversion assembly 852 comprises:

[0089] A second fixed tube 8521 is connected to a suction pump through a second gas inlet tube 8522, and the suction pump is fixed in the cooling bin 4.

[0090] Two second fixed plates are symmetrically fixed to the outer wall of the second fixed tube 8521 and are in communication with the inside of the second fixed tube 8521.

[0091] A second extrusion plate 8524 is provided with a plurality of second pistons 8523 slidingly arranged on the second fixed plate, and the second extrusion plate 8524 is fixedly connected to the middle position of the side of the cavity 82.

[0092] It should be noted that when the first conversion assembly 851 converts the cavity 82 into a circular shape, the simultaneous gas injection or gas extraction of the first conversion assembly 851 and the second conversion assembly 852 can make the outer wall of the cavity 82 move synchronously, thereby adjusting the size of the circular shape.

[0093] As a preferred embodiment, the diameter of the circular cavity 82 can be small at the center and large at the edge, thereby accurately matching the natural pressure distribution requirement of the silicon wafer 10 during polishing, providing optimal pressure distribution smoothness, and ensuring that the pressure uniformity is optimal, there is no stress concentration point, and the fatigue resistance is strong. The circular stress distribution is uniform, and the flexible membrane 84 can be used for a longer time under cyclic pressure.

[0094] As a preferred embodiment, when the conversion assembly 85 converts the cavity 82, the vertex position of the cavity 82 is first extruded by the first conversion assembly 851, and the second conversion assembly 852 is in a static state, so that the regular hexagonal cavity 82 is converted into a circular shape. When the size of the circular cavity 82 needs to be adjusted, the first conversion assembly 851 and the second conversion assembly 852 are synchronously driven.

[0095] In addition, optionally, the cavities 82 in the central region of the substrate 81 can be maintained as regular hexagons, the cavities 82 in the excessive region are converted into circular cavities, and the cavities 82 in the edge region are maintained as regular hexagons. In this case, the regular hexagonal cavities 82 can improve the filling rate and guarantee the resolution, and the circular cavities 82 can relieve the thermal expansion stress and improve the stability of the partition adjustment of the silicon wafer 10.

[0096] It should be noted that the shape of the cavities 82 at the junction of the excessive region and the central region and the edge region is a combination of a circle and a regular hexagon, and this state does not affect the adjustment of the pressure.

[0097] In the specific implementation, first, the back surface of the silicon wafer 10 is adhered and mounted on the flexible film 84 by the colloid, the hydraulic oil is injected into the liquid storage bin 3, and the pressure in each cavity is stabilized to the initial set value ±0.05 psi. Then, the polishing equipment drives the shell 1 to move close to the polishing disc, so that the silicon wafer 10 and the limiting ring 9 are in contact with the polishing disc. Then, the polishing operation is started. During polishing, when the silicon wafer 10 is locally uneven, the pressure value of the corresponding pressure sensor increases or decreases at this time. At this time, the micro pump valve 6 injects or extracts hydraulic oil into the cavity, so as to perform real-time partition adjustment and improve the response speed of the adjustment.

[0098] The above describes only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacements or changes to the technical solutions and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A silicon wafer polishing head pressure real-time adjustment system, characterized in that, include: The housing (1) is installed at the output end of the polishing equipment, and a rotary joint is installed on its upper end face; A partition plate (2) is fixed inside the housing (1) and divides the inside of the housing (1) into a liquid storage chamber (3) and a cooling chamber (4). The liquid storage chamber (3) is connected to an external liquid supply device by a rotary joint. A fixed plate (5) is fixed inside the cooling chamber (4); Multiple miniature pump valves (6) are configured, all fixed on the upper surface of the fixed plate (5) and connected to the liquid storage tank (3) by pipes; The controller (7) is fixed on the fixed plate (5) and electrically connected to multiple micro pump valves (6); The partition adjustment component (8) is fixed to the lower end face of the cooling chamber (4); The limiting ring (9) is vertically slidably disposed on the lower end face of the housing (1) and is connected to one of the micro pump valves (6) by means of the adjusting pipe (91); A silicon wafer (10) is mounted on the lower end face of the partition adjustment assembly (8) and located within the limiting ring (9); The partition adjustment component (8) includes: The substrate (81) is fixed to the lower end face of the cooling chamber (4), and a conversion chamber is provided on the side away from the cooling chamber (4); Multiple cavities (82) are configured and fixed inside the conversion chamber, and the cavities (82) are connected to multiple micro pump valves (6) by hoses; A sealing film (83) is fixed on the side of the substrate (81) away from the cooling chamber (4), and the sealing film (83) seals and isolates the plurality of cavities (82); A flexible membrane (84) is fixed to the side of the sealing membrane (83) away from the substrate (81); Multiple conversion components (85) are configured, all fixed within the conversion chamber and located between the multiple cavities (82); The suction tube (86) is fixed inside the cavity (82), with one end connected to the hose and the other end close to the sealing membrane (83) but not in contact with the sealing membrane (83).

2. The real-time pressure adjustment system for a silicon wafer polishing head according to claim 1, wherein, The outer wall of the housing (1) is provided with a plurality of cooling holes (11) at an angle corresponding to the cooling chamber (4). The plurality of cooling holes (11) are inclined toward the fixed plate (5) along the axial direction of the cooling chamber (4) and incline toward the rotation direction of the housing (1) along the radial direction of the cooling chamber (4).

3. The real-time pressure adjustment system for a silicon wafer polishing head according to claim 1, wherein, Pressure sensors are installed on the hoses connected to the multiple cavities. Vacuum adsorption holes are opened on the substrate (81) between the multiple cavities (82). The vacuum adsorption holes are connected to a vacuum pump fixed on the fixed plate (5).

4. The real-time pressure adjustment system for a silicon wafer polishing head according to claim 1, wherein, The initial shape of the cavity (82) is a regular hexagon, and the cavity (82) is made of a flexible material. The multiple conversion components (85) are located at the vertices and the middle of the sides of the regular hexagon.

5. The real-time pressure adjustment system for a silicon wafer polishing head according to claim 1, characterized in that, The conversion component (85) includes: The first conversion components (851) are configured in six and fixed at the apex position of the cavity (82); The second conversion assembly (852) is configured in six parts and fixed at the middle position of the side of the cavity (82).

6. The silicon wafer polishing head pressure real-time adjustment system according to claim 5, characterized in that, The first conversion component (851) includes: The first fixed pipe (8511) is connected to the suction pump via the first air inlet pipe (8512), and the suction pump is fixed inside the cooling chamber (4); The first fixing plate is configured as three, which are evenly fixed to the outer wall of the first fixing tube (8511) and communicate with the inside of the first fixing tube (8511). The first extrusion plate (8514) is slidably disposed on the first fixed plate by a plurality of first pistons (8513); A flexible column (8515) is fixed to one end of the first extrusion plate (8514) away from the first piston (8513) and is fixedly connected to the apex of the cavity (82).

7. The silicon wafer polishing head pressure real-time adjustment system according to claim 5, characterized in that, The second conversion component (852) includes: The second fixed pipe (8521) is connected to the suction pump via the second air inlet pipe (8522), and the suction pump is fixed inside the cooling chamber (4); The second fixing plate is configured as two, symmetrically fixed on the outer wall of the second fixing tube (8521), and communicates with the inside of the second fixing tube (8521); The second extrusion plate (8524) is slidably mounted on the second fixed plate by multiple second pistons (8523), and the second extrusion plate (8524) is fixedly connected to the middle position of the side of the cavity (82).

8. The real-time pressure adjustment system for a silicon wafer polishing head according to claim 5, characterized in that, When the conversion component (85) converts the cavity (82), the first conversion component (851) first squeezes the vertex of the cavity (82), and the second conversion component (852) is stationary, so that the regular hexagonal cavity (82) is converted into a circle. After that, when the size of the circular cavity (82) needs to be adjusted, the first conversion component (851) and the second conversion component (852) are driven synchronously.

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