Abrasive recovery device for silicon wafer polishing

Abstract

The utility model discloses an abrasive recovery device for silicon wafer polishing, which belongs to the technical field and comprises a waste liquid collecting tank, a primary cyclone, a secondary cyclone and a chemical sedimentation tank. The waste liquid collecting tank is connected with the first-stage cyclone through a pipeline, the first-stage cyclone is connected with the second-stage cyclone through a pipeline, the second-stage cyclone is connected with the chemical sedimentation tank, the first-stage cyclone is used for separating large-particle silicon wafer particles, and the second-stage cyclone is used for separating cerium oxide particles; flow guide grooves are formed in the inner wall of the first-stage cyclone and the inner wall of the second-stage cyclone, the flow guide grooves are spiral groove bodies from top to bottom, waste liquid is guided to flow along a spiral path, the centrifugal force effect is enhanced, the particle separation efficiency is improved, the depth of the flow guide grooves is gradually shallower from a feeding opening to an underflow opening, the movement track of particles is optimized, particle accumulation is reduced, and the particle separation efficiency is improved. The centrifugal force effect is obviously enhanced, and the separation efficiency of large-particle silicon wafer particles and cerium oxide particles is improved.

Description

Technical Field

[0001] This utility model belongs to the field of polishing abrasive recycling technology, and more specifically, relates to an abrasive recycling device for silicon wafer polishing. Background Technology

[0002] Chemical mechanical polishing (CMP) is a critical process in semiconductor manufacturing, widely used to improve the surface flatness of silicon wafers and remove surface damage layers to meet the high precision requirements of chip manufacturing. CMP typically uses a polishing slurry formed by mixing abrasives such as cerium oxide, silicon dioxide, and alumina with chemical polishing fluids to remove material from the silicon wafer surface. However, the CMP process generates a large amount of waste liquid containing silicon wafer particles, unreacted chemicals, and cerium oxide abrasive particles. Cerium oxide is a rare earth material and is expensive; direct disposal would result in a serious waste of resources. Traditional sedimentation methods for recovering cerium oxide... When cerium oxide is present, it is difficult to effectively separate it from silicon wafer particles and other impurities, resulting in low abrasive purity and difficulty in reuse. Existing membrane filtration methods do not easily separate cerium oxide from other particles in liquid, leading to low recovery efficiency. In hydrocyclone separation, due to the relatively small size of cerium oxide particles, they are easily affected by liquid disturbance, and when the waste liquid forms turbulence, it is easy to flow out from the overflow port with the waste liquid, resulting in low recovery rate. Chemical sedimentation equipment requires long-term static placement, has low processing efficiency, and occupies a large area, making it unsuitable for modern production environments. Therefore, there is a need for an abrasive recovery device for silicon wafer polishing that has a high recovery rate, is not easily disturbed by liquid, and has a compact structure. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide an abrasive recycling device for silicon wafer polishing, which can meet the requirements of high recycling rate, minimal liquid disturbance, and compact structure.

[0004] This utility model discloses an abrasive recovery device for silicon wafer polishing, comprising a waste liquid collection tank, a primary hydrocyclone, a secondary hydrocyclone, and a chemical precipitation tank. The waste liquid collection tank is connected to the primary hydrocyclone via a pipe, the primary hydrocyclone is connected to the secondary hydrocyclone via a pipe, and the secondary hydrocyclone is connected to the chemical precipitation tank. The primary hydrocyclone is used to separate large silicon wafer particles, and the secondary hydrocyclone is used to separate cerium oxide particles. The inner walls of the primary and secondary hydrocyclones are provided with guide channels, which are spiral-shaped channels from top to bottom to guide the waste liquid to flow along the spiral path, enhance the centrifugal force, and improve the particle separation efficiency.

[0005] As a further improvement of this utility model, both the primary hydrocyclone and the secondary hydrocyclone are provided with a feed inlet, an overflow inlet, and an underflow inlet. The feed inlet of the primary hydrocyclone is connected to the waste liquid collection tank, and the overflow inlet is connected to the feed inlet of the secondary hydrocyclone through a pipe. The underflow inlet of the secondary hydrocyclone is connected to the chemical precipitation tank. The hydrocyclone includes a conical section and a cylindrical section. The cylindrical section is located at the upper end of the conical section, and the feed inlet is located at the junction of the cylindrical section and the conical section. The axis of the cylindrical section is tangent to the circle formed by the cross-section of the top surface of the hydrocyclone, so that the particles are stratified according to density and size, thereby improving the separation efficiency.

[0006] As a further improvement of this utility model, the depth of the guide channel gradually becomes shallower from the feed inlet to the bottom outlet, which optimizes the movement trajectory of the particles, reduces particle accumulation, significantly enhances the centrifugal force, and improves the separation efficiency of large silicon wafer particles and cerium oxide particles.

[0007] As a further improvement of this utility model, the chemical precipitation tank is equipped with a stirrer, a pH regulator, and a pH sensor. The stirrer is vertically installed at the center of the chemical precipitation tank, and the pH regulator is located outside the chemical precipitation tank. The pH regulator is equipped with a controller, a dosing pump, and a dosing pipeline. The dosing pump is connected to an external precipitant, and the two ends of the dosing pipeline are connected to the dosing pump and the chemical precipitation tank, respectively. The controller is electrically connected to the dosing pump. The pH sensor is fixedly installed on the side wall of the chemical precipitation tank and is connected to the controller via a signal. The pH sensor is immersed in the waste liquid to monitor the pH value in real time and transmits a signal to the controller of the pH regulator. The pH regulator adds precipitant according to the sensor feedback to dynamically adjust the pH value and improve the precipitation efficiency of cerium oxide particles.

[0008] As a further improvement of this utility model, the cone angle of the conical section of the first-stage hydrocyclone is set as the cone angle of the first-stage hydrocyclone, which is 30°-35°. The cone angle of the conical section of the second-stage hydrocyclone is set as the cone angle of the second-stage hydrocyclone, which is 10°-15°. The cone angle of the first-stage hydrocyclone is greater than that of the second-stage hydrocyclone, thereby improving the separation accuracy of cerium oxide particles.

[0009] As a further improvement of this utility model, the feed inlet is designed with a tapered structure, and the inner diameter of the cylindrical section gradually decreases in the direction towards the conical section, thereby reducing the feed flow rate and reducing turbulence.

[0010] As a further improvement of this utility model, a rotating scraper is provided at one end of the first-stage hydrocyclone near the underflow outlet. One end of the rotating scraper is fixedly connected to the inner wall of the first-stage hydrocyclone, and the rotating scraper has a built-in motor. The rotation axis of the rotating scraper is the same as the axis of the conical section of the first-stage hydrocyclone, scraping off large silicon wafer particles attached to the underflow outlet to prevent large silicon wafer particles from causing blockage.

[0011] As a further improvement of this utility model, both the first-stage hydrocyclone and the second-stage hydrocyclone are equipped with turbulence suppressors. The turbulence suppressors are fixedly connected to the inner walls of the conical sections of the first-stage and second-stage hydrocyclones. The turbulence suppressors are coaxially installed with the inner walls of the hydrocyclones. The turbulence suppressors are provided with several evenly distributed side plates. The space formed between the side plates can guide the flow of waste liquid and reduce the potential energy of the waste liquid when it falls, thereby reducing turbulence in the flow of waste liquid and improving separation efficiency.

[0012] Compared to existing technologies, the advantages of this invention are as follows: A primary and secondary hydrocyclone are installed before chemical precipitation. Large particles such as silicon wafers are filtered out first through hydrocyclone separation, and then cerium oxide is separated from other small particles in the waste liquid. This improves the purity of the cerium oxide requiring chemical precipitation, reduces precipitation difficulty and time, and reduces precipitant consumption, saving costs. The inner walls of the primary and secondary hydrocyclones are equipped with guide channels to guide the waste liquid along a spiral path, enhancing centrifugal force and improving particle separation efficiency. The depth of the guide channels gradually decreases from the inlet to the outlet, optimizing particle separation. The movement trajectory of the particles reduces particle accumulation and enhances centrifugal force; the axis of the cylindrical section is tangent to the circle formed by the top cross-section of the hydrocyclone, causing particles to stratify according to density and size, improving separation efficiency; the chemical precipitation tank is equipped with a stirrer, pH adjuster, and pH sensor to dynamically adjust the pH value and improve the precipitation efficiency of cerium oxide particles; the cone angle of the conical section of the first-stage hydrocyclone is larger than that of the conical section of the second-stage hydrocyclone, improving the separation accuracy of cerium oxide particles; the feed inlet is designed with a tapered structure to reduce the feed flow rate and reduce turbulence; a turbulence suppressor is installed to reduce turbulence in the waste liquid flow and improve separation efficiency. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of this utility model;

[0014] Figure 2 This is a schematic diagram of the hydrocyclone structure of this utility model;

[0015] Figure 3 This is a schematic diagram of the chemical precipitation tank structure of this utility model;

[0016] Figure 4 This is a cross-sectional view of the hydrocyclone and a schematic diagram of the guide channel structure of this utility model;

[0017] Figure 5 For the present utility model Figure 4 Enlarged view of the region;

[0018] Figure 6 This is a cross-sectional view of the hidden guide groove of the first-stage hydrocyclone of this utility model.

[0019] Figure 7 This is a cross-sectional view of the hidden guide groove of the secondary cyclone separator of this utility model.

[0020] Figure 8 This is a schematic diagram of the rotating scraper structure of this utility model;

[0021] Figure 9 This is a schematic diagram of the turbulence suppressor structure of this utility model.

[0022] Explanation of the labels in the diagram:

[0023] Waste liquid collection tank 1; primary hydrocyclone 2; secondary hydrocyclone 3; feed inlet 4; overflow outlet 5; underflow outlet 6; rotating scraper 61; guide channel 7; chemical precipitation tank 8; agitator 81; pH regulator 82; pH sensor 83; turbulence suppressor 9; cone angle a of primary hydrocyclone; cone angle b of secondary hydrocyclone. Detailed Implementation

[0024] Specific Implementation Example 1: Please refer to... Figures 1-9 This utility model relates to an abrasive recycling device for silicon wafer polishing, comprising a waste liquid collection tank 1, a primary hydrocyclone 2, a secondary hydrocyclone 3, and a chemical precipitation tank 8. The waste liquid collection tank 1 is connected to the primary hydrocyclone 2 via a pipe, the primary hydrocyclone 2 is connected to the secondary hydrocyclone 3 via a pipe, and the secondary hydrocyclone 3 is connected to the chemical precipitation tank 8. The primary hydrocyclone 2 is used to separate large silicon wafer particles, and the secondary hydrocyclone 3 is used to separate cerium oxide particles.

[0025] In a further embodiment, such as Figure 2 and Figures 4-7 As shown, both the primary hydrocyclone 2 and the secondary hydrocyclone 3 are equipped with a feed inlet 4, an overflow outlet 5, and an underflow outlet 6. The feed inlet 4 of the primary hydrocyclone 2 is connected to the waste liquid collection tank 1, and the overflow outlet 5 is connected to the feed inlet 4 of the secondary hydrocyclone 3 through a pipe. The underflow outlet 6 of the secondary hydrocyclone 3 is connected to the chemical precipitation tank 8. The hydrocyclone includes a conical section and a cylindrical section. The cylindrical section is located at the upper end of the conical section. The feed inlet 4 is located at the junction of the cylindrical section and the conical section, and the axis of the cylindrical section is tangent to the circle formed by the cross-section of the top surface of the hydrocyclone, so that the particles are stratified according to density and size, thereby improving the separation efficiency.

[0026] In a further embodiment, such as Figures 4-5 As shown, the inner walls of the primary hydrocyclone 2 and the secondary hydrocyclone 3 are provided with guide channels 7. The guide channels 7 are spiral-shaped channels from top to bottom, which guide the waste liquid to flow along the spiral path, enhance the centrifugal force, and improve the particle separation efficiency. The depth of the guide channels 7 gradually becomes shallower from the feed inlet 4 to the bottom outlet 6, which optimizes the movement trajectory of the particles, reduces particle accumulation, enhances the centrifugal force, and improves the separation efficiency of large silicon wafer particles and cerium oxide particles.

[0027] In a further embodiment, such as Figure 3As shown, the chemical precipitation tank 8 is equipped with a stirrer 81, a pH regulator 82, and a pH sensor 83. The stirrer 81 is vertically installed at the center of the chemical precipitation tank 8. The pH regulator 82 is located outside the chemical precipitation tank 8 and is equipped with a controller, a dosing pump, and a dosing pipeline. The dosing pump is connected to an external precipitant, and the two ends of the dosing pipeline are connected to the dosing pump and the chemical precipitation tank 8, respectively. The controller is electrically connected to the dosing pump. The pH sensor 83 is fixedly installed on the side wall of the chemical precipitation tank 8 and is connected to the controller via a signal. The pH sensor 83 is immersed in the waste liquid to monitor the pH value in real time and transmits a signal to the controller of the pH regulator 82. The pH regulator 82 adds precipitant according to the feedback from the pH sensor 83 to dynamically adjust the pH value and improve the precipitation efficiency of cerium oxide particles.

[0028] In a further embodiment, such as Figures 6-7 As shown, the cone angle of the conical section of the first-stage hydrocyclone 2 is set as the cone angle a of the first-stage hydrocyclone, which is 30°. The cone angle of the conical section of the second-stage hydrocyclone 3 is set as the cone angle b of the second-stage hydrocyclone, which is 15°. The cone angle a of the first-stage hydrocyclone is greater than the cone angle b of the second-stage hydrocyclone to improve the separation accuracy of cerium oxide particles.

[0029] In a further embodiment, such as Figures 6-7 As shown, the feed inlet 4 is designed with a tapered structure, where the inner diameter of the cylindrical section gradually decreases in the direction toward the conical section, thereby reducing the feed flow rate and turbulence.

[0030] In a further embodiment, such as Figure 6 and Figure 8 As shown, a rotating scraper 61 is provided at one end of the first-stage hydrocyclone 2 near the underflow port 6. One end of the rotating scraper 61 is fixedly connected to the inner wall of the first-stage hydrocyclone 2, and a motor is built into the rotating scraper 61. The rotation axis of the rotating scraper 61 is the same as the axis of the conical section of the first-stage hydrocyclone 2. It scrapes off large silicon wafer particles attached to the underflow port 6 to prevent large silicon wafer particles from causing blockage.

[0031] In a further embodiment, such as Figures 6-7 and Figure 9 As shown, both the primary hydrocyclone 2 and the secondary hydrocyclone 3 are equipped with turbulence suppressors 9. The turbulence suppressors 9 are fixedly connected to the inner wall of the conical section of the primary hydrocyclone 2 and the secondary hydrocyclone 3. The turbulence suppressors 9 are coaxially installed with the inner wall of the hydrocyclone. The turbulence suppressors 9 are provided with several evenly distributed side plates. The space formed between the side plates can guide the flow of waste liquid and reduce the potential energy of the waste liquid when it falls, thereby reducing turbulence in the flow of waste liquid and improving separation efficiency.

[0032] Waste liquid from waste liquid collection tank 1 is discharged into primary hydrocyclone 2. The waste liquid enters from inlet 4 of primary hydrocyclone 2. Under the action of centrifugal force, large silicon wafer particles move axially downward and radially outward, forming an outer vortex flow field. After reaching the conical section, they move downward along the wall and are finally discharged from the bottom outlet 6. Cerium oxide particles and some liquid move towards the central axis, forming an upward-moving inner vortex at the center of the axis, and are finally discharged from the overflow outlet 5, thus achieving the removal of silicon wafer debris. Cerium oxide particles and some liquid enter secondary hydrocyclone 3 from overflow outlet 5. In secondary hydrocyclone 3, due to their higher density, cerium oxide particles move towards the outer wall of secondary hydrocyclone 3 and are discharged from the bottom outlet 6, and then enter chemical precipitation tank 8. Small impurities and residual liquid are discharged from overflow outlet 5 for subsequent wastewater treatment. Cerium oxide particles are precipitated in chemical precipitation tank 8 and finally filtered out.

Claims

1. An abrasive recovery device for silicon wafer polishing, characterized by: The application relates to a waste liquid treatment device, which comprises a waste liquid collecting tank (1), a primary cyclone (2), a secondary cyclone (3) and a chemical precipitation tank (8), the waste liquid collecting tank (1) is connected with the primary cyclone (2) through a pipeline, the primary cyclone (2) is connected with the secondary cyclone (3) through a pipeline, the secondary cyclone (3) is connected with the chemical precipitation tank (8), the inner wall of the primary cyclone (2) and the secondary cyclone (3) is provided with a flow guide groove (7), and the flow guide groove (7) is designed as a spiral groove body from top to bottom.

2. The apparatus of claim 1, wherein: The primary cyclone (2) and the secondary cyclone (3) are both provided with a feeding port (4), an overflow port (5) and an underflow port (6), the feeding port (4) of the primary cyclone (2) is connected with the waste liquid collecting tank (1), the overflow port (5) is connected with the feeding port (4) of the secondary cyclone (3) through a pipeline, the underflow port (6) of the secondary cyclone (3) is connected with the chemical precipitation tank (8), the cyclone comprises a conical section and a cylindrical section, the cylindrical section is located at the upper end of the conical section, and the feeding port (4) is arranged at the joint of the cylindrical section and the conical section.

3. The apparatus of claim 1 wherein: The chemical precipitation tank (8) is provided with a stirrer (81), a pH regulator (82) and a pH sensor (83), the stirrer (81) is vertically arranged at the center of the chemical precipitation tank (8), the pH regulator (82) is arranged outside the chemical precipitation tank, the pH regulator (82) is provided with a controller, a dosing pump and a dosing pipeline, the dosing pump is connected with an external precipitant, the two ends of the dosing pipeline are connected with the dosing pump and the chemical precipitation tank (8) respectively, the controller is electrically connected with the dosing pump, and the pH sensor is fixedly arranged on the side wall of the chemical precipitation tank (8) and is signal-connected with the controller.

4. The apparatus of claim 2 wherein: The conical angle of the conical section of the primary cyclone (2) is a primary cyclone conical angle (a), the primary cyclone conical angle (a) is 30-35 DEG, the conical angle of the conical section of the secondary cyclone (3) is a secondary cyclone conical angle (b), the secondary cyclone conical angle (b) is 10-15 DEG, and the primary cyclone conical angle (a) is larger than the secondary cyclone conical angle (b).

5. The apparatus of claim 2 wherein: the first and second rotatable members are mounted on a common shaft; and the first and second rotatable members are mounted on the common shaft such that the first and second rotatable members rotate in opposite directions. The primary cyclone (2) and the secondary cyclone (3) are both provided with a turbulence inhibitor (9), the turbulence inhibitor (9) is fixedly connected to the inner wall of the conical section of the primary cyclone (2) and the secondary cyclone (3), and the turbulence inhibitor (9) is coaxially arranged with the inner wall.

6. The apparatus of claim 2 wherein: The feeding port (4) is designed as a tapered structure, and the inner diameter of the cylindrical section gradually decreases in the direction towards the conical section.

7. The apparatus of claim 1 wherein: the polishing pad is a silicon wafer polishing pad. The depth of the flow guide groove (7) gradually decreases in the direction from the feeding port (4) to the underflow port (6).

8. The apparatus of claim 2 wherein: the polishing pad is a silicon wafer polishing pad. One end of the primary cyclone (2) close to the underflow port (6) is provided with a rotary scraper (61), one end of the rotary scraper (61) is fixedly connected with the inner wall of the primary cyclone (2), a motor is arranged in the rotary scraper (61), and the rotating shaft of the rotary scraper (61) is the same as the axis of the conical section of the primary cyclone (2).

Images