A classification filter device for an alumina polishing liquid for semiconductor materials and a method thereof

Abstract

The application relates to the technical field of semiconductor processing auxiliary equipment, in particular to a grading filter device for an alumina polishing solution for semiconductor materials and a method thereof, which comprises an outer barrel body, a pre-filtering device arranged at the top end of the outer barrel body, a double-layer centrifugal cylinder rotatably connected to the inside of the outer barrel body, a rotating shaft rotatably connected to the central axis of the pre-filtering device and the double-layer centrifugal cylinder, and a stirring device arranged on the rotating shaft, and first ceramic filter membranes and second ceramic filter membranes are arranged on the inner layer and the outer layer of the double-layer centrifugal cylinder respectively. The filter screen and the scraping assembly arranged in the pre-filtering device can remove large-particle impurities in the alumina polishing solution, the double-layer centrifugal cylinder can perform grading filtration on the alumina polishing solution, the vertical rod, the straight rod, the separating piece and the cleaning piece arranged in the stirring device can stir the alumina polishing solution, the surfaces of the first ceramic filter membranes and the second ceramic filter membranes are cleaned, and the separation efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor processing auxiliary equipment, in particular to a grading filter device for aluminum oxide polishing liquid for semiconductor materials and a method thereof. BACKGROUND

[0002] The polishing liquid is a water-soluble polishing agent without any sulfur, phosphorus, and chlorine additives. The polishing liquid has good oil removal, rust prevention, cleaning, and polishing properties, and can make metal products show the true metal luster. In the semiconductor manufacturing process, the purity of the aluminum oxide polishing liquid is directly related to the surface quality of the wafer.

[0003] The authorized announcement No. CN215611188U discloses a configuration device for aluminum oxide polishing liquid, which comprises a shell, a feed inlet is formed on one side of the top end of the shell, a grinding groove is installed between the inner sides of the upper end of the shell, a second driving motor is installed on the top end of the shell, the output end of the second driving motor extends to the inside of the grinding groove through the shell, a connecting shaft is installed on the output end of the second driving motor, an installation rod is arranged at the bottom end of the connecting shaft, a plurality of fixing rods are installed at the bottom end of the installation rod, and a grinding block is installed at the bottom end of each fixing rod. The configuration device for aluminum oxide polishing liquid can grind the material by setting the grinding block and the grinding groove, so that the diameter of the abrasive particles in the material is more uniform, the material can be ground more thoroughly by setting the first and second protrusions, and the material can be filtered by the filter screen to avoid the influence of the large diameter of the abrasive particles on the subsequent polishing.

[0004] It can be seen that the existing filter does not pre-filter the aluminum oxide polishing liquid to remove impurities, and cannot grade filter the polishing liquid to obtain aluminum oxide polishing liquid with different particle sizes. In the grading filtering process, the surface of the filter material is not cleaned, which reduces the filtering efficiency.

[0005] In view of this, we propose a grading filter device for aluminum oxide polishing liquid for semiconductor materials and a method thereof. SUMMARY

[0006] In order to overcome the defects in the prior art, the purpose of the present application is to provide a grading filter device for aluminum oxide polishing liquid for semiconductor materials and a method thereof to solve the problems raised in the background art.

[0007] To achieve the above object, in one aspect, the application provides a kind of grading filtering device of alumina polishing solution for semiconductor material, including outer barrel body, pre-filter device being arranged at the top of the outer barrel body, double-layer centrifugal cylinder being rotatably connected in the inside of the outer barrel body, rotating shaft being rotatably connected on the central axis of the pre-filter device and the double-layer centrifugal cylinder, and stirring device being arranged on the rotating shaft, first ceramic filter membrane and second ceramic filter membrane are respectively arranged on the inner layer and outer layer of the double-layer centrifugal cylinder, the bottom end of the rotating shaft is coaxially connected with first gear after passing through the bottom surface of the double-layer centrifugal cylinder, second gear being fixedly welded at the center of the bottom surface of the double-layer centrifugal cylinder and being oppositely arranged with the first gear, a group of third gears being rotatably connected in the base of the outer barrel body and being symmetrically arranged, and the third gears are engaged with the first gear and the second gear.

[0008] The pre-filter device includes a pre-filter box, a filter screen arranged inside the pre-filter box, and a scraping assembly installed above the filter screen. The scraping assembly includes a fixed frame installed on the outer sidewall of the rotating shaft and a plurality of scrapers installed on the fixed frame.

[0009] The stirring device includes a mounting bracket arranged on the outer sidewall of the rotating shaft, a plurality of vertical rods rotatably connected to the mounting bracket, a separation piece arranged on the outer sidewall of the vertical rod, and a cleaning piece arranged on the vertical rod. The mounting bracket includes a plurality of mounting plates distributed radially. A straight rod is rotatably connected to the mounting plate. A plurality of vertical rods on the same mounting plate are connected by the straight rod. The cleaning piece is arranged on the vertical rod near the inner layer and the outer sidewall of the double-layer centrifugal cylinder. A plurality of worms are arranged on the straight rod. A worm wheel is arranged on the upper end of the vertical rod. A plurality of fan blades are arranged radially on the upper surface of the separation piece.

[0010] 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 with the rotating shaft. A funnel-shaped feed pipe is arranged at the top end of the pre-filter box.

[0011] As a further improvement of the technical solution, the bottom end of the side rod of the fixed frame is provided with a clamping groove matching the size of the scraper. The scraper is inserted into the clamping groove and fixed by locking bolts. The bottom end of the scraper abuts against the top surface of the filter screen.

[0012] As a further improvement of the technical solution, a first motor is installed at the top end of the mounting plate. The output shaft of the first motor is coaxially connected with one of the vertical rods on the mounting plate.

[0013] As a further improvement of the technical solution, a fixing seat is arranged at the corresponding position of the vertical rod at the bottom end of the mounting plate. A limiting ring matching the fixing seat is arranged on the outer sidewall of the vertical rod.

[0014] As a further improvement of the technical solution, the rotating shaft is welded with a spiral blade on the outer side wall of the inner part of the double-layer centrifugal cylinder, and the spiral blade rotates spirally upward with the rotating shaft.

[0015] As a further improvement of the technical solution, the cleaning member is composed of a cleaning roller and a fine brush plate and a sponge plate arranged on the cleaning roller, and the end of the fine brush plate and the sponge plate respectively abuts against the inner side wall of the first ceramic filter membrane and the second ceramic filter membrane.

[0016] As a further improvement of the technical solution, the side wall of the cleaning roller is regularly provided with a plurality of installation grooves matching the size of the fine brush plate and the sponge plate in the circumference, and the top end of the cleaning roller is fixed with a snap ring through a plurality of fastening bolts.

[0017] As a further improvement of the technical solution, the vertical rod provided with the separation member is arranged 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 rotating direction of the cleaning member is opposite to the rotating direction of the double-layer centrifugal cylinder, and the pore size of the first ceramic filter membrane is larger than that of the second ceramic filter membrane.

[0018] On the other hand, the application provides a grading filtering method of an alumina polishing liquid for semiconductor materials, comprising the following steps:

[0019] S1, first, the alumina polishing liquid is poured into the pre-filter box through the feeding pipe, falls on the filter screen, and is pre-filtered, the second motor is started to drive the fixed frame to rotate, so that the scraper rotates along the upper surface of the filter screen;

[0020] S2, at this time, the pre-filtered alumina polishing liquid falls into the inner layer of the double-layer centrifugal cylinder, the rotating shaft rotates to drive the first gear to rotate, the second gear drives the third gear to rotate, and then the double-layer centrifugal cylinder and the rotating shaft rotate in opposite directions, and the spiral blade rotates with the rotating shaft;

[0021] S3, then, the first motor is started to drive the coaxial vertical rod to rotate, under the transmission action of the worm on the straight rod and the worm wheel on the vertical rod, the other vertical rods are driven to rotate, so that the separation member rotates to stir the alumina polishing liquid, and the cleaning member rotates to clean the double-layer centrifugal cylinder;

[0022] S4, finally, under the action of centrifugal force, the large particles of alumina are left in the inner layer of the double-layer centrifugal cylinder, the medium particles of alumina pass through the first ceramic filter membrane and are left between the inner layer and the outer layer of the double-layer centrifugal cylinder, and the small particles of alumina pass through the second ceramic filter membrane and are left between the double-layer centrifugal cylinder and the outer barrel.

[0023] Compared with the prior art, the application has the following advantages:

[0024] 1. The semiconductor material with alumina polishing liquid grading filter device and method thereof, through the filter screen and scraping assembly provided in the pre-filter device, large particle impurities in the alumina polishing liquid can be removed.

[0025] 2. The semiconductor material with alumina polishing liquid grading filter device and method thereof, through the double-layer centrifugal cylinder provided, the alumina polishing liquid can be graded and filtered, and alumina polishing liquid with different particle sizes can be obtained.

[0026] 3. The semiconductor material with alumina polishing liquid grading filter device and method thereof, through the vertical rod, straight rod, separation piece and cleaning piece provided in the stirring device, the alumina polishing liquid in the double-layer separation cylinder can be stirred, and the cleaning piece can clean the surface of the first ceramic filter membrane and the second ceramic filter membrane, improve the separation efficiency, and make the grading filtration more thorough. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes and proportions of the components in the drawings are only illustrative and are used to help understand the present application, and are not specific limitations on the shapes and proportions of the components of the present application. Those skilled in the art can select various possible shapes and proportions to implement the present application according to specific circumstances under the guidance of the present application.

[0028] Figure 1 is a schematic diagram of the overall structure of the present application;

[0029] Figure 2 is a sectional view of the overall structure of the present application;

[0030] Figure 3 is an exploded view of the overall structure of the present application;

[0031] Figure 4 is a sectional view of the pre-filter device structure of the present application;

[0032] Figure 5 is an exploded view of the scraping assembly structure of the present application;

[0033] Figure 6 is an exploded view of the stirring device structure of the present application;

[0034] Figure 7 is a sectional view of the separation piece structure of the present application; Figure 6 is an enlarged view of A in the present application;

[0035] Figure 8 is a schematic diagram of the separation piece structure of the present application;

[0036] Figure 9 is an exploded view of the cleaning piece structure of the present application;

[0037] Figure 10 Enlarged view of B in FIG. 1; Figure 9 Enlarged view of B in FIG. 1;

[0038] The meanings of various reference numerals in the drawings are as follows:

[0039] 1. outer barrel body;

[0040] 2. pre-filtering device; 21, pre-filtering box; 22, feeding pipe; 23, filter screen; 24, scraping assembly; 241, fixing frame; 2411, clamping groove; 242, scraper; 243, locking bolt;

[0041] 3. double-layer centrifugal cylinder; 31, first ceramic filter membrane; 32, second ceramic filter membrane; 33, second gear;

[0042] 4. rotating shaft; 41, helical blade; 42, first gear;

[0043] 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 piece; 541, cleaning roller; 5411, mounting groove; 542, fine brush plate; 543, sponge plate; 544, clamping ring; 545, fastening bolt; 55, separating piece; 551, fan blade; 56, first motor;

[0044] 6. second motor;

[0045] 7. third gear. DETAILED DESCRIPTION

[0046] The details of the application can be more clearly understood with reference to the drawings and the following description. However, the specific embodiments of the application described herein are intended for purposes of illustration only and are not intended to be limiting in any way. These embodiments are presented as being illustrative of the application and its best mode and are not intended to limit the scope of the application. One of ordinary skill in the art will readily recognize from the disclosure herein, without departing from the scope of the application, certain modifications or equivalent arrangements intended to fall within the scope of the application. The terms "mounting", "connected" should be construed broadly and can mean either a direct connection, or an indirect connection via an intermediate medium.

[0047] The terms "central axis", "vertical", "horizontal", "front", "back", "upper", "lower", "left", "right", "top", "bottom", "inner", "outer" and the like as used herein to indicate orientation or positional relationships based on the orientation or position shown in the drawings, are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the application. In addition, in the description of the application, the meaning of "several" is two or more, unless otherwise explicitly specified.

[0048] Referring to Figures 1-10 As shown in the drawings, the application provides a kind of grading filter device for alumina polishing solution of semiconductor material, including outer barrel 1, pre-filter device 2 being arranged at the top of outer barrel 1, double-layer centrifugal cylinder 3 being rotatably connected in the inside of outer barrel 1, rotating shaft 4 being rotatably connected on the central axis of pre-filter device 2 and double-layer centrifugal cylinder 3 and stirring device 5 being arranged on rotating shaft 4, first ceramic filter membrane 31 and second ceramic filter membrane 32 are respectively arranged on the inner layer and outer layer of double-layer centrifugal cylinder 3, first gear 42 is coaxially connected on the bottom end of rotating shaft 4 after passing through the bottom surface of double-layer centrifugal cylinder 3, second gear 33 is fixedly welded at the center of the bottom surface of double-layer centrifugal cylinder 3 and is oppositely arranged with first gear 42, a group of third gears 7 are rotatably connected in the base of outer barrel 1 and are symmetrically arranged, third gears 7 are all engaged with first gear 42 and second gear 33, first gear 42 drives third gears 7 to rotate, in turn drives second gear 33 to rotate, in turn makes double-layer centrifugal cylinder 3 and rotating shaft 4 reverse rotation;

[0049] Pre-filter device 2 includes pre-filter box 21, filter screen 23 arranged in the inside of pre-filter box 21 and scraping assembly 24 installed above filter screen 23, scraping assembly 24 includes fixed frame 241 installed on the outer side wall of rotating shaft 4 and a plurality of scrapers 242 installed on fixed frame 241, scrapers 242 facilitate to scrape impurity particles blocked on filter screen 23;

[0050] Stirring device 5 includes mounting bracket 51 arranged on the outer side wall of rotating shaft 4, a plurality of vertical rods 52 rotatably connected on mounting bracket 51, separation piece 55 arranged on the outer side wall of vertical rod 52 and cleaning piece 54 arranged on vertical rod 52, mounting bracket 51 includes a plurality of mounting plates 511 distributed in a radial manner, straight rod 53 is rotatably connected in mounting plate 511, a plurality of vertical rods 52 located on the same mounting plate 511 are drivingly connected through straight rod 53, cleaning piece 54 is arranged on vertical rod 52 close to the inner layer and the outer side inner side wall of double-layer centrifugal cylinder 3, and cleaning piece 54 cleans first ceramic filter membrane 31 and second ceramic filter membrane 32;A plurality of worms 531 are arranged on straight rod 53, worm wheel 521 is arranged on the upper end of vertical rod 52, and the matching worm 531 and worm wheel 521 enable driving connection between a plurality of vertical rods 52;A plurality of fan blades 551 distributed in a radial manner are arranged on the upper surface of separation piece 55, and the design of fan blades 551 facilitates to stir alumina polishing solution, so that it is thrown to both sides, so that the grading filtration is more thorough.

[0051] Specifically, second motor 6 is installed at the center of the top surface of pre-filter box 21, the output shaft of second motor 6 is coaxially connected with rotating shaft 4, and second motor 6 provides power for the rotation of rotating shaft 4;Funnel-shaped feed pipe 22 is arranged at the top end of pre-filter box 21, and the funnel-shaped feed pipe 22 facilitates to pour alumina polishing solution into pre-filter box 21.

[0052] Further, the side rod bottom end of the fixing frame 241 is provided with a clamping groove 2411 matched with the size of the scraper 242, the scraper 242 is inserted into the clamping groove 2411 and is fixed by the locking bolt 243, the locking bolt 243 is used for conveniently installing and replacing the scraper 242; the bottom end of the scraper 242 abuts against the top surface of the filter screen 23, so that the scraper 242 can scrape and clean the filter screen 23.

[0053] Specifically, the mounting plate 511 is provided with the first motor 56 at the top end, the output shaft of the first motor 56 is coaxially connected with 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.

[0054] In addition, the mounting plate 511 is provided with a fixing seat 512 at the bottom end corresponding to the vertical rod 52, and the fixing seat 512 fixes the vertical rod 52; the outer side wall of the vertical rod 52 is provided with a limiting ring 522 matched with the fixing seat 512, and the limiting ring 522 limits the rotation of the vertical rod 52.

[0055] Further, the outer side wall of the part of the rotating shaft 4 located in the inner part of the double-layer centrifugal cylinder 3 is welded with a spiral blade 41, the spiral blade 41 rotates spirally upward with the rotating shaft 4, and the spiral blade 41 facilitates the stirring of the aluminum oxide polishing liquid, so that the liquid spirally upward, and the stirring is complete.

[0056] 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 abut against the inner side walls of the first ceramic filter membrane 31 and the second ceramic filter membrane 32 respectively, the vertical rod 52 drives the cleaning roller 541 to rotate, and 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, avoiding blockage.

[0057] It is worth noting that the side wall of the cleaning roller 541 is regularly provided with a plurality of installation grooves 5411 matched with the sizes of the fine brush plate 542 and the sponge plate 543, the top end of the cleaning roller 541 is fixed with a snap ring 544 through a plurality of fastening bolts 545, and the design of the snap ring 544 and the installation grooves 5411 facilitates the installation and replacement of the fine brush plate 542 and the sponge plate 543.

[0058] Further, the vertical rod 52 provided with the separating member 55 is arranged in 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 rotating direction of the cleaning member 54 is opposite to the rotating direction of the double-layer centrifugal cylinder 3, the opposite rotating directions make the cleaning member 54 more convenient for cleaning the first ceramic filter membrane 31 and the second ceramic filter membrane 32, and the pore diameter of the first ceramic filter membrane 31 is greater than that of the second ceramic filter membrane 32.

[0059] The method comprises the following steps:

[0060] S1, first, the alumina polishing solution is poured into the pre-filter box 21 through the feeding pipe 22 and falls on the filter screen 23 for pre-filtering, 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 and scrapes off the impurities blocked on the filter screen 23;

[0061] S2, at this time, the pre-filtered alumina polishing solution falls into the inner layer of the double-layer centrifugal cylinder 3, the rotating shaft 4 rotates to drive the first gear 42 to rotate, the third gear 7 is driven to rotate through the second gear 33, and the double-layer centrifugal cylinder 3 and the rotating shaft 4 rotate in opposite directions, and the spiral blade 41 rotates with the rotating shaft 4 to stir the alumina polishing solution;

[0062] S3, then, the first motor 56 is started to drive the coaxial vertical rod 52 to rotate, the worm 531 on the straight rod 53 and the worm gear 521 on the vertical rod 52 are driven to rotate other vertical rods 52, so that the separation piece 55 rotates to stir the alumina polishing solution and accelerate the classification and filtration efficiency, and the cleaning piece 54 rotates to clean the double-layer centrifugal cylinder 3 and remove the particles blocked on the first ceramic filter membrane 31 and the second ceramic filter membrane 32;

[0063] S4, finally, under the action of centrifugal force, large particles of alumina are left in the inner layer of the double-layer centrifugal cylinder 3, medium particles of alumina pass through the first ceramic filter membrane 31 and are left between the inner layer and the outer layer of the double-layer centrifugal cylinder 3, and small particles of alumina pass through the second ceramic filter membrane 32 and are left between the double-layer centrifugal cylinder 3 and the outer barrel 1.

[0064] It should be noted that the above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A fractional filtration device for an alumina polishing solution for semiconductor materials, characterized by: The utility model provides a double -layer centrifugal cylinder is provided with first ceramic filter membrane and second ceramic filter membrane on the inner layer and the outer layer respectively, and the first gear and the second gear are coaxially connected to the bottom end of the rotating shaft after penetrating through the bottom surface of the double -layer centrifugal cylinder, and the third gear is rotatably connected to the base of the outer barrel, and the third gear is engaged with the first gear and the second gear, and the prefiltering device includes a prefiltering box, a filter screen arranged in the prefiltering box and a scraping assembly installed above the filter screen, the scraping assembly includes a fixed frame installed on the outer side wall of the rotating shaft and a plurality of scrapers installed on the fixed frame, and 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 mounting plates distributed in a radial manner, a straight rod is rotatably connected in the mounting plate, a plurality of vertical rods on the same mounting plate are drivingly connected through the straight rod, the cleaning piece is arranged on the vertical rod close to the inner layer and the outer side of the double -layer centrifugal cylinder, a plurality of worms are arranged on the straight rod, a worm wheel is arranged on the upper end of the vertical rod, and a plurality of fan blades are arranged on the upper surface of the separating piece in a radial manner. The utility model provides a double -layer centrifugal cylinder is provided with first ceramic filter membrane and second ceramic filter membrane on the inner layer and the outer layer respectively, and the first gear and the second gear are coaxially connected to the bottom end of the rotating shaft after penetrating through the bottom surface of the double -layer centrifugal cylinder, and the third gear is rotatably connected to the base of the outer barrel, and the third gear is engaged with the first gear and the second gear, and the prefiltering device includes a prefiltering box, a filter screen arranged in the prefiltering box and a scraping assembly installed above the filter screen, the scraping assembly includes a fixed frame installed on the outer side wall of the rotating shaft and a plurality of scrapers installed on the fixed frame, and 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 mounting plates distributed in a radial manner, a straight rod is rotatably connected in the mounting plate, a plurality of vertical rods on the same mounting plate are drivingly connected through the straight rod, the cleaning piece is arranged on the vertical rod close to the inner layer and the outer side of the double -layer centrifugal cylinder, a plurality of worms are arranged on the straight rod, a worm wheel is arranged on the upper end of the vertical rod, and a plurality of fan blades are arranged on the upper surface of the separating piece in a radial manner. The utility model provides a double -layer centrifugal cylinder is provided with first ceramic filter membrane and second ceramic filter membrane on the inner layer and the outer layer respectively, and the first gear and the second gear are coaxially connected to the bottom end of the rotating shaft after penetrating through the bottom surface of the double -layer centrifugal cylinder, and the third gear is rotatably connected to the base of the outer barrel, and the third gear is engaged with the first gear and the second gear, and the prefiltering device includes a prefiltering box, a filter screen arranged in the prefiltering box and a scraping assembly installed above the filter screen, the scraping assembly includes a fixed frame installed on the outer side wall of the rotating shaft and a plurality of scrapers installed on the fixed frame, and 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 mounting plates distributed in a radial manner, a straight rod is rotatably connected in the mounting plate, a plurality of vertical rods on the same mounting plate are drivingly connected through the straight rod, the cleaning piece is arranged on the vertical rod close to the inner layer and the outer side of the double -layer centrifugal cylinder, a plurality of worms are arranged on the straight rod, a worm wheel is arranged on the upper end of the vertical rod, and a plurality of fan blades are arranged on the upper surface of the separating piece in a radial manner. The utility model provides a double -layer centrifugal cylinder is provided with first ceramic filter membrane and second ceramic filter membrane on the inner layer and the outer layer respectively, and the first gear and the second gear are coaxially connected to the bottom end of the rotating shaft after penetrating through the bottom surface of the double -layer centrifugal cylinder, and the third gear is rotatably connected to the base of the outer barrel, and the third gear is engaged with the first gear and the second gear, and the prefiltering device includes a prefiltering box, a filter screen arranged in the prefiltering box and a scraping assembly installed above the filter screen, the scraping assembly includes a fixed frame installed on the outer side wall of the rotating shaft and a plurality of scrapers installed on the fixed frame, and 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 mounting plates distributed in a radial manner, a straight rod is rotatably connected in the mounting plate, a plurality of vertical rods on the same mounting plate are drivingly connected through the straight rod, the cleaning piece is arranged on the vertical rod close to the inner layer and the outer side of the double -layer centrifugal cylinder, a plurality of worms are arranged on the straight rod, a worm wheel is arranged on the upper end of the vertical rod, and a plurality of fan blades are arranged on the upper surface of the separating piece in a radial manner. ​ The cleaning piece (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), and the end of the fine brush plate (542) and the sponge plate (543) abuts against the inner side wall of the first ceramic filter membrane (31) and the second ceramic filter membrane (32) respectively. The side wall of the cleaning roller (541) is regularly provided with a plurality of installation grooves (5411) which are adapted to the size of the fine brush plate (542) and the sponge plate (543) along the circumference, and the top end of the cleaning roller (541) is fixed with a snap ring (544) through a plurality of fastening bolts (545).

2. The fractional filtration apparatus for an alumina polishing solution for semiconductor materials according to claim 1, characterized by: 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 with the rotating shaft (4), and a funnel-shaped feeding pipe (22) is arranged at the top end of the pre-filter box (21).

3. The apparatus for fractional filtration of an alumina polishing liquid for semiconductor materials according to claim 1, characterized in that: The side rods of the fixing frame (241) are all provided with clamping grooves (2411) which are adapted to the size of the scraper (242) at the bottom end, the scraper (242) is inserted into the clamping grooves (2411) and is fixed through locking bolts (243), and the bottom end of the scraper (242) abuts against the top surface of the filter screen (23).

4. The fractional filtration apparatus for alumina polishing solution for semiconductor materials according to claim 1, characterized in that: A first motor (56) is installed at the top end of the mounting plate (511), and the output shaft of the first motor (56) is coaxially connected with one of the vertical rods (52) on the mounting plate (511).

5. The fractional filtration apparatus for alumina polishing solution for semiconductor materials according to claim 1, characterized in that: The vertical rod (52) provided with the separating piece (55) is arranged 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 rotating direction of the cleaning piece (54) is opposite to the rotating direction of the double-layer centrifugal cylinder (3), and the pore size of the first ceramic filter membrane (31) is larger than that of the second ceramic filter membrane (32).

6. A method for fractionally filtering an alumina polishing liquid for a semiconductor material, using the fractionally filtering apparatus for an alumina polishing liquid for a semiconductor material according to any one of claims 1 to 5, characterized by, The method comprises the following steps: S1, first, pour the alumina polishing solution into the pre-filter box (21) through the feeding pipe (22), fall on the filter screen (23), and pre-filter, start the second motor (6), drive the fixing 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 alumina polishing solution falls into the inner layer of the double-layer centrifugal cylinder (3), the rotating shaft (4) rotates, drives the first gear (42) to rotate, drives the third gear (7) to rotate through the second gear (33), and then drives the double-layer centrifugal cylinder (3) and the rotating shaft (4) to rotate in opposite directions, and the spiral blade (41) rotates with the rotating shaft (4); S3, then, start the first motor (56), drive the coaxial vertical rod (52) to rotate, under the transmission 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 separating piece (55) rotates and stirs the alumina polishing solution, and the cleaning piece (54) rotates to clean the double-layer centrifugal cylinder (3); S4. Finally, under the action of centrifugal force, large alumina particles remain in the inner layer of the double-layer centrifuge tube (3), medium alumina particles pass through the first ceramic filter membrane (31) and remain between the inner and outer layers of the double-layer centrifuge tube (3), and small alumina particles pass through the second ceramic filter membrane (32) and remain between the double-layer centrifuge tube (3) and the outer barrel (1).

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