Graded filtering device and method for aluminum oxide polishing solution for semiconductor material

Abstract

The invention relates to the technical field of semiconductor processing auxiliary equipment, in particular to a graded filtering device and method for an aluminum oxide polishing solution for a semiconductor material. Comprising an outer barrel body, a pre-filtering device arranged at the top end of the outer barrel body, a double-layer centrifugal barrel rotationally connected to the interior of the outer barrel body, a rotating shaft rotationally connected to the central axis of the pre-filtering device and the central axis of the double-layer centrifugal barrel, and a stirring device arranged on the rotating shaft. And a first ceramic filter membrane and a second ceramic filter membrane are respectively arranged on the inner layer and the outer layer of the double-layer centrifugal cylinder. Large-particle impurities in an aluminum oxide polishing solution can be removed through a filter screen and a scraping assembly which are arranged in the pre-filtering device, the aluminum oxide polishing solution can be filtered in a classified mode through a double-layer centrifugal barrel, and meanwhile the aluminum oxide polishing solution can be stirred through a vertical rod, a straight rod, a separation piece and a cleaning piece which are arranged in the stirring device; the surfaces of the first ceramic filter membrane and the second ceramic filter membrane are cleaned, so that the separation efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor processing auxiliary equipment, in particular to a grading filtering device and method for alumina polishing liquid for semiconductor materials. Background Art

[0002] Polishing liquid is a water-soluble polishing agent that does not contain any sulfur, phosphorus, or chlorine additives. The polishing liquid has good degreasing, rust prevention, cleaning, and gloss enhancement properties, and can make metal products show a true metallic luster. In the semiconductor manufacturing process, the purity of the alumina polishing liquid is directly related to the surface quality of the chip.

[0003] Authorization announcement number CN215611188U discloses a device for dispensing aluminum oxide polishing liquid, including a shell, a feed port is provided on one side of the top of the shell, a grinding groove is installed at the upper end between the two sides inside the shell, a second drive motor is installed at the top of the shell, the output end of the second drive motor extends through the shell to the inside of the grinding groove, a connecting shaft is installed at the output end of the second drive motor, a mounting rod is provided at the bottom end of the connecting shaft, a plurality of fixed rods are installed at the bottom end of the mounting rod, and a grinding block is installed at the bottom end of each fixed rod. The device for dispensing aluminum oxide polishing liquid can grind the material by providing the grinding block and the grinding groove, so that the diameter of the abrasive particles inside the material can be more uniform, and the material can be ground more thoroughly by providing the first protrusion and the second protrusion, and the material can be filtered through the filter to avoid the influence of the abrasive particle diameter being too large on the subsequent polishing.

[0004] It can be seen that the existing filtration does not pre-filter the alumina polishing liquid to remove impurities, and cannot grade the polishing liquid to obtain alumina polishing liquid with different particle sizes. At the same time, during the graded filtration process, the filter material surface is not cleaned, which reduces the filtration efficiency.

[0005] In view of this, we propose a graded filtration device and method for alumina polishing liquid for semiconductor materials. Summary of the invention

[0006] In order to overcome the defects in the prior art, the purpose of the present invention is to provide a grading filtration device and method for alumina polishing liquid for semiconductor materials to solve the problems raised in the above background technology.

[0007] To achieve the above-mentioned purpose, on the one hand, the present invention provides a graded filtration device for alumina polishing liquid for semiconductor materials, comprising an outer barrel, a pre-filter device arranged at the top of the outer barrel, a double-layer centrifugal cylinder rotatably connected to the inside of the outer barrel, a rotating shaft rotatably connected to the pre-filter device and the central axis of the double-layer centrifugal cylinder, and a stirring device arranged on the rotating shaft, the inner layer and the outer layer of the double-layer centrifugal cylinder are respectively provided with a first ceramic filter membrane and a second ceramic filter membrane, the bottom end of the rotating shaft passes through the bottom surface of the double-layer centrifugal cylinder and is coaxially connected to a first gear, a second gear arranged opposite to the first gear is welded and fixed at the center of the bottom surface of the double-layer centrifugal cylinder, a group of symmetrically arranged third gears are rotatably connected in the base of the outer barrel, and the third gear is meshed with both the first gear and the second gear; The pre-filter device comprises a pre-filter box, a filter screen arranged inside the pre-filter box, and a scraping assembly installed above the filter screen, wherein the scraping assembly comprises a fixing frame installed on the outer side wall of the rotating shaft and a plurality of scrapers installed on the fixing frame; The stirring device includes a mounting frame arranged on the outer side wall of the rotating shaft, a plurality of vertical rods rotatably connected to the mounting frame, a separating piece arranged on the outer side wall of the vertical rod, and a cleaning piece arranged on the vertical rod. The mounting frame includes a plurality of radially distributed mounting plates, a straight rod is rotatably connected in the mounting plate, and a plurality of the vertical rods located on the same mounting plate are transmission-connected via the straight rod. The cleaning piece is arranged on the vertical rod close to the inner layer and the outer side wall of the double-layer centrifugal cylinder, a plurality of worms are arranged on the straight rod, a worm gear is arranged at the upper end of the vertical rod, and a plurality of radially distributed fan blades are arranged on the upper surface of the separating piece.

[0008] As a further improvement of the technical solution, a second motor is installed at the center of the top surface of the pre-filter box, the output shaft of the second motor is coaxially connected to the rotating shaft, and a funnel-shaped feed pipe is provided at the top of the pre-filter box.

[0009] As a further improvement of the technical solution, the bottom ends of the side rods of the fixing frame are provided with slots adapted to the size of the scraper, the scraper is inserted into the slots and fixed by locking bolts, and the bottom ends of the scrapers are in contact with the top surface of the filter.

[0010] As a further improvement of the technical solution, a first motor is installed on the top of the mounting plate, and the output shaft of the first motor is coaxially connected to one of the vertical rods on the mounting plate.

[0011] As a further improvement of the technical solution, a fixing seat is provided at the bottom end of the mounting plate at a position corresponding to the vertical rod, and a limiting ring matched with the fixing seat is provided on the outer side wall of the vertical rod.

[0012] As a further improvement of the technical solution, spiral blades are welded and fixed on the outer wall of the rotating shaft located in the inner part of the double-layer centrifugal cylinder, and the spiral blades rotate spirally upward along with the rotating shaft.

[0013] As a further improvement of the present technical solution, the cleaning piece is composed of a cleaning roller and a fine brush plate and a sponge plate arranged on the cleaning roller, and the ends of the fine brush plate and the sponge plate are respectively abutted against the inner walls of the first ceramic filter membrane and the second ceramic filter membrane.

[0014] As a further improvement of the technical solution, a plurality of mounting grooves matching the sizes of the fine brush plate and the sponge plate are regularly opened along the circumference of the side wall of the cleaning roller, and a retaining ring is fixed to the top of the cleaning roller by a plurality of fastening bolts.

[0015] As a further improvement of the present technical solution, the vertical rod provided with the separation piece is placed inside the inner layer of the double-layer centrifugal cylinder and between the inner layer and the outer layer of the double-layer centrifugal cylinder, the rotation direction of the cleaning piece is opposite to the rotation direction of the double-layer centrifugal cylinder, and the pore size of the first ceramic filter membrane is larger than the pore size of the second ceramic filter membrane.

[0016] In another aspect, the present invention provides a method for graded filtration of an aluminum oxide polishing liquid for semiconductor materials, comprising the following steps: S1. First, pour the alumina polishing liquid into the pre-filter box through the feed pipe and let it fall on the filter screen for pre-filtration. Start the second motor to drive the fixed frame to rotate, so that the scraper rotates along the upper surface of the filter screen. S2. At this time, the pre-filtered aluminum oxide polishing liquid falls into the inner layer of the double-layer centrifugal cylinder, the rotating shaft rotates, driving the first gear to rotate, and the third gear to rotate through the second gear, so that the double-layer centrifugal cylinder and the rotating shaft rotate in the opposite direction, and the spiral blade rotates with the rotating shaft; S3, then, start the first motor to drive the coaxial vertical rod to rotate, and under the transmission action of the worm on the straight rod and the worm wheel on the vertical rod, drive the other vertical rods to rotate, so that the separation part rotates to stir the alumina polishing liquid, and the cleaning part rotates to clean the double-layer centrifugal cylinder; S4. Finally, under the action of centrifugal force, the large particles of aluminum oxide in the aluminum oxide polishing liquid remain in the inner layer of the double-layer centrifugal cylinder, the medium particles of aluminum oxide pass through the first ceramic filter membrane and remain between the inner and outer layers of the double-layer centrifugal cylinder, and the small particles of aluminum oxide pass through the second ceramic filter membrane and remain between the double-layer centrifugal cylinder and the outer barrel.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The device and method for grading and filtering alumina polishing liquid for semiconductor materials can remove large particle impurities in the alumina polishing liquid through the filter screen and scraping assembly provided in the pre-filter device.

[0018] 2. The device and method for grading and filtering alumina polishing liquid for semiconductor materials can grade and filter the alumina polishing liquid through a double-layer centrifugal cylinder to obtain alumina polishing liquid with different particle sizes.

[0019] 3. The device and method for grading and filtering alumina polishing liquid for semiconductor materials can stir the alumina polishing liquid in the double-layer separation cylinder through the vertical rods, straight rods, separation parts and cleaning parts provided in the stirring device. At the same time, the cleaning parts can clean the surfaces of the first ceramic filter membrane and the second ceramic filter membrane, thereby improving the separation efficiency and making the graded filtration more thorough. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings described herein are only for explanation purposes and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the various components in the figures are only schematic, used to help understand the present invention, and are not specifically limited to the shapes and proportional dimensions of the various components of the present invention. Those skilled in the art can select various possible shapes and proportional dimensions to implement the present invention according to the teachings of the present invention.

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a cross-sectional view of the overall structure of the present invention; Figure 3 It is an exploded view of the overall structure of the present invention; Figure 4 It is a cross-sectional view of the structure of the pre-filter device of the present invention; Figure 5 An exploded view of the scraping assembly structure of the present invention; Figure 6 It is an exploded view of the stirring device structure of the present invention; Figure 7 For the present invention Figure 7 A magnified view of middle; Figure 8 It is a schematic diagram of the separation structure of the present invention; Fig. 9 An exploded view of the cleaning member structure of the present invention; Fig.10 For the present invention Fig. 9 Enlarged view of middle B; The meaning of each number in the figure is: 1. Outer barrel; 2. Pre-filter device; 21. Pre-filter box; 22. Feed pipe; 23. Filter screen; 24. Scraping assembly; 241. Fixing frame; 2411. Card slot; 242. Scraper; 243. Locking bolt; 3. Double-layer centrifugal cylinder; 31. First ceramic filter membrane; 32. Second ceramic filter membrane; 33. Second gear; 4. Rotating shaft; 41. Helical blade; 42. First gear; 5. stirring device; 51. mounting frame; 511. mounting plate; 512. fixing seat; 52. vertical rod; 521. worm gear; 522. limiting ring; 53. straight rod; 531. worm; 54. cleaning member; 541. cleaning roller; 5411. mounting groove; 542. fine brush plate; 543. sponge plate; 544. snap ring; 545. fastening bolt; 55. separating member; 551. fan blade; 56. first motor; 6. Second motor; 7. Third gear. DETAILED DESCRIPTION

[0022] The details of the present invention can be more clearly understood by combining the accompanying drawings with the description of the specific embodiments of the present invention. However, the specific embodiments of the present invention described herein are only used for the purpose of explaining the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be regarded as falling within the scope of the present invention. The terms "installation" and "connection" should be understood in a broad sense, which can be directly connected or indirectly connected through an intermediate medium.

[0023] The terms "central axis", "vertical", "horizontal", "front", "back", "up", "down", "left", "right", "top", "bottom", "inside", "outside" and the like used herein to indicate positions or positional relationships are based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the equipment or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0024] See also Figure 1-Figure 10As shown, the present invention provides a graded filtering device for alumina polishing liquid for semiconductor materials, comprising an outer barrel body 1, a pre-filtering device 2 arranged at the top of the outer barrel body 1, a double-layer centrifugal cylinder 3 rotatably connected to the inside of the outer barrel body 1, a rotating shaft 4 rotatably connected to the central axis of the pre-filtering device 2 and the double-layer centrifugal cylinder 3, and a stirring device 5 arranged on the rotating shaft 4, the inner layer and the outer layer of the double-layer centrifugal cylinder 3 are respectively provided with a first ceramic filter membrane 31 and a second ceramic filter membrane 32, the bottom end of the rotating shaft 4 passes through the bottom surface of the double-layer centrifugal cylinder 3 and is coaxially connected to a first gear 42, a second gear 33 arranged opposite to the first gear 42 is welded and fixed at the center of the bottom surface of the double-layer centrifugal cylinder 3, a group of symmetrically arranged third gears 7 are rotatably connected in the base of the outer barrel body 1, the third gear 7 is meshed with the first gear 42 and the second gear 33, the first gear 42 rotates to drive the third gear 7 to rotate, and then drives the second gear 33 to rotate, so that the double-layer centrifugal cylinder 3 and the rotating shaft 4 rotate in the opposite direction; The pre-filter device 2 includes a pre-filter box 21, a filter screen 23 disposed inside the pre-filter box 21, and a scraping assembly 24 installed above the filter screen 23. The scraping assembly 24 includes a fixing frame 241 installed on the outer wall of the rotating shaft 4 and a plurality of scrapers 242 installed on the fixing frame 241. The scrapers 242 are convenient for scraping away foreign particles blocked on the filter screen 23. The stirring device 5 includes a mounting frame 51 arranged on the outer wall of the rotating shaft 4, a plurality of vertical rods 52 rotatably connected to the mounting frame 51, a separation member 55 arranged on the outer wall of the vertical rod 52, and a cleaning member 54 arranged on the vertical rod 52. The mounting frame 51 includes a plurality of radially distributed mounting plates 511, a straight rod 53 is rotatably connected inside the mounting plate 511, and a plurality of vertical rods 52 located on the same mounting plate 511 are connected by the straight rod 53. The cleaning member 54 is arranged near the inner layer of the double-layer centrifugal cylinder 3. On the vertical rod 52 connected to the inner wall of the outer side, the cleaning part 54 cleans the first ceramic filter membrane 31 and the second ceramic filter membrane 32; a plurality of worms 531 are provided on the straight rod 53, and a worm wheel 521 is provided on the upper end of the vertical rod 52. The matching worms 531 and worm wheels 521 enable transmission connection between the plurality of vertical rods 52; a plurality of radially distributed fan blades 551 are provided on the upper surface of the separation part 55. The design of the fan blades 551 facilitates stirring of the alumina polishing liquid so that it is thrown out to both sides, making the graded filtration more thorough.

[0025] Specifically, a second motor 6 is installed at the center of the top surface of the pre-filter box 21. The output shaft of the second motor 6 is coaxially connected to the rotating shaft 4, and the second motor 6 provides power for the rotation of the rotating shaft 4. A funnel-shaped feed pipe 22 is provided at the top of the pre-filter box 21. The funnel-shaped feed pipe 22 facilitates pouring alumina polishing liquid into the pre-filter box 21.

[0026] Furthermore, the bottom ends of the side rods of the fixing frame 241 are provided with slots 2411 that are adapted to the size of the scraper 242. The scraper 242 is inserted into the slots 2411 and fixed by locking bolts 243. The locking bolts 243 are used to facilitate the installation and replacement of the scraper 242; the bottom end of the scraper 242 abuts against the top surface of the filter 23, making it convenient for the scraper 242 to scrape and clean the filter 23.

[0027] Specifically, a first motor 56 is installed at the top of the mounting plate 511 , and an output shaft of the first motor 56 is coaxially connected to one of the vertical rods 52 on the mounting plate 511 , and the first motor 56 provides power for the rotation of the vertical rod 52 .

[0028] In addition, a fixing seat 512 is provided at the bottom end of the mounting plate 511 at a position corresponding to the vertical rod 52, and the fixing seat 512 fixes the vertical rod 52; a limiting ring 522 adapted to the fixing seat 512 is provided on the outer wall of the vertical rod 52 to limit the vertical rod 52 when it rotates.

[0029] Furthermore, a spiral blade 41 is welded and fixed on the outer wall of the rotating shaft 4 located in the inner part of the double-layer centrifugal cylinder 3. The spiral blade 41 spirals upward as the rotating shaft 4 rotates. The spiral blade 41 facilitates stirring the aluminum oxide polishing liquid so that the liquid is stirred thoroughly as it spirals upward.

[0030] Specifically, the cleaning member 54 is composed of a cleaning roller 541 and a fine brush plate 542 and a sponge plate 543 arranged on the cleaning roller 541. The ends of the fine brush plate 542 and the sponge plate 543 are respectively abutted against the inner walls of the first ceramic filter membrane 31 and the second ceramic filter membrane 32. The rotation of the vertical rod 52 drives the cleaning roller 541 to rotate. The cleaning roller 541 rotates, so that the fine brush plate 542 and the sponge plate 543 clean the first ceramic filter membrane 31 and the second ceramic filter membrane 32 to avoid blockage.

[0031] It is worth mentioning that a plurality of mounting grooves 5411 matching the sizes of the fine brush plate 542 and the sponge plate 543 are regularly opened along the circumference of the side wall of the cleaning roller 541, and a retaining ring 544 is fixed to the top of the cleaning roller 541 by a plurality of fastening bolts 545. The design of the retaining ring 544 and the mounting groove 5411 facilitates the installation and replacement of the fine brush plate 542 and the sponge plate 543.

[0032] Furthermore, a vertical rod 52 provided with a separation piece 55 is placed inside the inner layer of the double-layer centrifugal cylinder 3 and between the inner layer and the outer layer of the double-layer centrifugal cylinder 3. The rotation direction of the cleaning piece 54 is opposite to the rotation direction of the double-layer centrifugal cylinder 3. The opposite rotation direction makes it easier for the cleaning piece 54 to clean the first ceramic filter membrane 31 and the second ceramic filter membrane 32; the pore size of the first ceramic filter membrane 31 is larger than the pore size of the second ceramic filter membrane 32.

[0033] The method for graded filtration of alumina polishing liquid for semiconductor materials of the present invention comprises the following steps: S1. First, the aluminum oxide polishing liquid is poured into the pre-filter box 21 through the feed pipe 22 and falls on the filter screen 23 for pre-filtration. The second motor 6 is started to drive the fixed frame 241 to rotate, so that the scraper 242 rotates along the upper surface of the filter screen 23 to scrape off the impurities blocking the filter screen 23. S2. At this time, the pre-filtered aluminum oxide polishing liquid falls into the inner layer of the double-layer centrifugal cylinder 3, and the rotating shaft 4 rotates, driving the first gear 42 to rotate, and the third gear 7 to rotate through the second gear 33, so that the double-layer centrifugal cylinder 3 and the rotating shaft 4 rotate in the opposite direction, and the spiral blade 41 rotates with the rotating shaft 4 to stir the aluminum oxide polishing liquid; S3, then, start the first motor 56 to drive the coaxial vertical rod 52 to rotate, and under the transmission action of the worm 531 on the straight rod 53 and the worm wheel 521 on the vertical rod 52, drive the other vertical rods 52 to rotate, so that the separation member 55 rotates to stir the alumina polishing liquid to accelerate the graded filtration efficiency, and the cleaning member 54 rotates to clean the double-layer centrifugal cylinder 3 to remove the particles blocked on the first ceramic filter membrane 31 and the second ceramic filter membrane 32; S4. Finally, under the action of centrifugal force, the large particles of aluminum oxide in the aluminum oxide polishing liquid remain in the inner layer of the double-layer centrifugal cylinder 3, the medium particles of aluminum oxide pass through the first ceramic filter membrane 31 and remain between the inner and outer layers of the double-layer centrifugal cylinder 3, and the small particles of aluminum oxide pass through the second ceramic filter membrane 32 and remain between the double-layer centrifugal cylinder 3 and the outer barrel 1.

[0034] It should be noted that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A grading filtration device for alumina polishing liquid for semiconductor materials, characterized in that: The invention comprises an outer barrel (1), a pre-filter device (2) arranged at the top of the outer barrel (1), a double-layer centrifugal cylinder (3) rotatably connected to the inside of the outer barrel (1), a rotating shaft (4) rotatably connected to the pre-filter device (2) and the central axis of the double-layer centrifugal cylinder (3), and a stirring device (5) arranged on the rotating shaft (4), wherein a first ceramic filter membrane (31) and a second ceramic filter membrane (32) are respectively arranged on the inner layer and the outer layer of the double-layer centrifugal cylinder (3), the bottom end of the rotating shaft (4) passes through the bottom surface of the double-layer centrifugal cylinder (3) and is coaxially connected to a first gear (42), a second gear (33) arranged opposite to the first gear (42) is welded and fixed at the center of the bottom surface of the double-layer centrifugal cylinder (3), and a group of symmetrically arranged third gears (7) are rotatably connected in the base of the outer barrel (1), and the third gear (7) is meshed with both the first gear (42) and the second gear (33); The pre-filter device (2) comprises a pre-filter box (21), a filter screen (23) arranged inside the pre-filter box (21), and a scraping assembly (24) installed above the filter screen (23); the scraping assembly (24) comprises a fixing frame (241) installed on the outer side wall of the rotating shaft (4) and a plurality of scrapers (242) installed on the fixing frame (241); The stirring device (5) comprises a mounting frame (51) arranged on the outer wall of the rotating shaft (4), a plurality of vertical rods (52) rotatably connected to the mounting frame (51), a separating member (55) arranged on the outer wall of the vertical rod (52), and a cleaning member (54) arranged on the vertical rod (52); the mounting frame (51) comprises a plurality of mounting plates (511) distributed radially; a straight rod (53) is rotatably connected inside the mounting plate (511); a plurality of vertical rods (52) located on the same mounting plate (511) are transmission-connected via the straight rod (53); the cleaning member (54) is arranged on the vertical rod (52) near the inner layer and the outer inner wall of the double-layer centrifugal cylinder (3); a plurality of worms (531) are arranged on the straight rod (53); a worm wheel (521) is arranged at the upper end of the vertical rod (52); and a plurality of fan blades (551) distributed radially are arranged on the upper surface of the separating member (55).

2. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: A second motor (6) is installed at the center of the top surface of the pre-filter box (21); an output shaft of the second motor (6) is coaxially connected to the rotating shaft (4); and a funnel-shaped feed pipe (22) is provided at the top of the pre-filter box (21).

3. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: The bottom ends of the side rods of the fixing frame (241) are each provided with a slot (2411) that matches the size of the scraper (242); the scraper (242) is inserted into the slot (2411) and fixed by a locking bolt (243); the bottom end of the scraper (242) abuts against the top surface of the filter screen (23).

4. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: A first motor (56) is mounted on the top of the mounting plate (511), and an output shaft of the first motor (56) is coaxially connected to one of the vertical rods (52) on the mounting plate (511).

5. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: A fixing seat (512) is provided at the bottom end of the mounting plate (511) at a position corresponding to the vertical rod (52), and a limiting ring (522) adapted to the fixing seat (512) is provided on the outer side wall of the vertical rod (52).

6. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: The rotating shaft (4) is located at the outer wall of the inner part of the double-layer centrifugal cylinder (3), and a spiral blade (41) is welded and fixed thereto. The spiral blade (41) rotates in a spiral upward along with the rotating shaft (4).

7. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: The cleaning member (54) is composed of a cleaning roller (541) and a fine brush plate (542) and a sponge plate (543) arranged on the cleaning roller (541); the ends of the fine brush plate (542) and the sponge plate (543) are respectively in contact with the inner side walls of the first ceramic filter membrane (31) and the second ceramic filter membrane (32).

8. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 7, characterized in that: A plurality of mounting grooves (5411) matching the sizes of the fine brush plate (542) and the sponge plate (543) are regularly formed on the side wall of the cleaning roller (541) along the circumference, and a clamping ring (544) is fixed to the top end of the cleaning roller (541) via a plurality of fastening bolts (545).

9. The grading filtration device for alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: The vertical rod (52) provided with the separation member (55) is placed inside the inner layer of the double-layer centrifugal cylinder (3) and between the inner layer and the outer layer of the double-layer centrifugal cylinder (3); the rotation direction of the cleaning member (54) is opposite to the rotation direction of the double-layer centrifugal cylinder (3); and the pore size of the first ceramic filter membrane (31) is larger than the pore size of the second ceramic filter membrane (32).

10. A method for graded filtration of an aluminum oxide polishing liquid for semiconductor materials, using the graded filtration device for aluminum oxide polishing liquid for semiconductor materials according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. First, the aluminum oxide polishing liquid is poured into the pre-filter box (21) through the feed pipe (22) and falls on the filter screen (23) for pre-filtration. The second motor (6) is started to drive the fixed frame (241) to rotate, so that the scraper (242) rotates along the upper surface of the filter screen (23); S2. At this time, the pre-filtered aluminum oxide polishing liquid falls into the inner layer of the double-layer centrifugal cylinder (3), the rotating shaft (4) rotates, driving the first gear (42) to rotate, and the third gear (7) to rotate through the second gear (33), thereby causing the double-layer centrifugal cylinder (3) and the rotating shaft (4) to rotate in opposite directions, and the spiral blade (41) rotates along with the rotating shaft (4); S3, then, starting the first motor (56) to drive the coaxial vertical rod (52) to rotate, and under the transmission action of the worm (531) on the straight rod (53) and the worm wheel (521) on the vertical rod (52), the other vertical rods (52) are driven to rotate, so that the separation member (55) rotates to stir the alumina polishing liquid, and the cleaning member (54) rotates to clean the double-layer centrifugal cylinder (3); S4. Finally, under the action of centrifugal force, the alumina polishing liquid has large particles of alumina remaining in the inner layer of the double-layer centrifugal cylinder (3), medium particles of alumina passing through the first ceramic filter membrane (31) remaining between the inner layer and the outer layer of the double-layer centrifugal cylinder (3), and small particles of alumina passing through the second ceramic filter membrane (32) remaining between the double-layer centrifugal cylinder (3) and the outer barrel (1).

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