Method for recovering and supplying a silicon wafer processing slurry

Abstract

This invention relates to a method for recycling and supplying polishing slurry in silicon wafer processing, belonging to the technical field of silicon wafer processing equipment. It includes a silicon wafer polishing assembly, a return liquid sedimentation tank connected to the lower end of the assembly via piping, a stirring tank on the side of the assembly, a return liquid pipe between the upper end of the stirring tank and the lower part of the return liquid sedimentation tank, a circulating pump II connected to the return liquid pipe via a threaded connection within the sedimentation tank, a grid cover on the stirring tank, a stirring shaft at the lower end of the grid cover, and a stirring pump connected to the stirring shaft via a splined retaining ring at the upper end of the grid cover. A circulating pump I is also located on the grid cover, and a polishing slurry inlet pipe connects the circulating pump I to the silicon wafer polishing assembly. This method features a compact structure and good operational stability. It solves the problem of maintaining the overall density of the polishing slurry supplied to the processing section, improves the entire recycling process of the polishing slurry, and reduces the risk of surface scratches.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer processing equipment technology, and specifically to a method for recovering and supplying silicon wafer processing polishing slurry. Background Technology

[0002] As device feature sizes shrink, the quality requirements for the silicon wafer crystal portion become increasingly stringent. For polished silicon wafers, native crystal defects are a crucial characteristic. After the crystal ingot is pulled, it undergoes processes such as rolling, grooving, slicing, chamfering, and polishing before undergoing inspection for native crystal defects.

[0003] Grinding, also known as wafer polishing, is a process that uses polishing slurry on a grinding machine to grind silicon wafers to achieve a certain thickness and smoothness. There are two methods: single-sided grinding and double-sided grinding.

[0004] Grinding plays a crucial role in silicon wafer manufacturing. Due to the high intensity of mechanical processing, mechanical damage is a serious problem, resulting in a high scrap rate, which can severely impact subsequent processes.

[0005] Grinding operations require the use of a certain amount of grinding fluid; as the grinding powder particles gradually decrease in size during use, their presence level in the circulating grinding tank gradually rises, resulting in the amount of grinding powder in the normally supplied grinding fluid being replenished. Summary of the Invention

[0006] This invention primarily addresses the shortcomings of existing technologies by providing a method for recycling and supplying polishing slurry in silicon wafer processing. This method features a compact structure and good operational stability. It solves the problem of maintaining the overall density of the polishing slurry supplied to the processing section. Furthermore, it improves the entire recycling process of the polishing slurry, reducing the risk of surface scratches.

[0007] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions:

[0008] A method for recycling and supplying silicon wafer processing polishing slurry, the structure comprising a silicon wafer polishing assembly, a return liquid sedimentation tank connected to the lower end of the silicon wafer polishing assembly via a pipeline, a stirring tank on the side of the silicon wafer polishing assembly, a return liquid pipe between the upper end of the stirring tank and the lower part of the return liquid sedimentation tank, a circulating pump II connected to the return liquid pipe via a threaded connection within the return liquid sedimentation tank, a grid cover on the stirring tank, a stirring shaft at the lower end of the grid cover, a stirring pump connected to the stirring shaft via a splined retaining ring at the upper end of the grid cover, a circulating pump I on the grid cover, and a polishing slurry inlet pipe between the circulating pump I and the silicon wafer polishing assembly.

[0009] A method for recovering and supplying polishing slurry in silicon wafer processing includes the following steps:

[0010] Step 1: Add 60L of pure water to the mixing tank, install the grating tank cover, and turn on the circulation pump I and the mixing pump.

[0011] Step 2: Add 5-10L of weak alkaline dispersant stock solution to the mixing tank and stir for 15-30 minutes.

[0012] Step 3: Add 30-50 kg of the Al2O3 and zirconate mixture to the mixing tank and stir continuously.

[0013] Step 4: Set the power of the stirring pump to 0.4-0.8KW and the power of the circulating pump I to 1-1.5KW.

[0014] Step 5: Manually place the silicon wafer into the customized carrier hole on the platen of the silicon wafer grinding assembly, start the silicon wafer grinding assembly, and begin the grinding process. Each round of processing takes about 10 minutes. After the target is achieved, remove the processed silicon wafer and continue to place the next batch of silicon wafers.

[0015] Step 6: After the grinding liquid in the mixing tank has been used multiple times, drain it and clean the mixing tank.

[0016] Preferably, the silicon wafer polishing assembly includes a carrier on which a plurality of silicon wafers are fixed in a clamping fixture. An upper polishing disc is provided above the carrier, and a thickness probe is provided inside the upper polishing disc. A lower polishing disc is provided at the lower end of the carrier, and a plurality of polishing slurry channels are provided on the lower polishing disc, which are connected to polishing slurry inlet pipes. The polishing slurry channels are respectively connected to the silicon wafers.

[0017] Preferably, a grinding return liquid tray is provided between the lower grinding disc and the return liquid sedimentation tank. The upper end of the grinding return liquid tray is provided with several return liquid ring grooves, and the grinding return liquid tray is provided with a return liquid channel that communicates with the return liquid ring grooves and the return liquid sedimentation tank.

[0018] Preferably, the grid cover is provided with lifting guide rails on both sides and the inner wall of the mixing tank, and the upper two sides of the grid cover are provided with lifting cylinders that slide movably along the lifting guide rails.

[0019] As a preferred option, the silicon wafer processing time is 10 minutes per round. The grid barrel cover is raised by a lifting cylinder, and it is raised by 2mm for each processing round. When the circulating liquid pump I cannot draw up the polishing liquid, the circulating polishing liquid can no longer be used and needs to be drained and the mixing barrel cleaned. At the same time, the lifting cylinder is reset to the lowest initial position.

[0020] Preferably, the circulating pump II is provided with a grid filter plate that is fixedly connected to the inner wall of the return sedimentation tank.

[0021] Preferably, the grinding slurry inlet pipe is provided with a replenishment pipe that is connected to the grinding slurry inlet pipe.

[0022] The present invention can achieve the following effects:

[0023] This invention provides a method for recycling and supplying polishing slurry in silicon wafer processing. Compared with existing technologies, it features a compact structure and good operational stability. It solves the problem of maintaining the overall density of the polishing slurry supplied to the processing section. It improves the entire recycling process of the polishing slurry and reduces the risk of surface scratches. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention.

[0025] Figure 2 This is a cross-sectional view of the silicon wafer grinding assembly of the present invention.

[0026] In the diagram: 1. Silicon wafer grinding assembly; 2. Grinding slurry inlet pipe; 3. Lifting cylinder; 4. Liquid replenishment pipe; 5. Circulating pump I; 6. Stirring pump; 7. Lifting guide rail; 8. Grille cover; 9. Stirring tank; 10. Return pipe; 11. Circulating pump II; 12. Return sedimentation tank; 13. Grille filter plate; 14. Grinding slurry channel; 15. Upper grinding disc; 16. Thickness probe; 17. Silicon wafer; 18. Carrier; 19. Lower grinding disc; 20. Grinding slurry return tray; 21. Return channel; 22. Return ring groove; 23. Detailed Implementation

[0027] The technical solution of the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0028] Example: Figure 1 and Figure 2 As shown, a method for recycling and supplying silicon wafer processing polishing slurry is disclosed. The silicon wafer processing polishing slurry recycling and supply structure includes a silicon wafer polishing assembly 1. The lower end of the silicon wafer polishing assembly 1 is provided with a return liquid sedimentation tank 13 connected to the silicon wafer polishing assembly 1 by a pipeline. A stirring tank 9 is provided on the side of the silicon wafer polishing assembly 1. A return liquid pipe 11 is provided between the upper end of the stirring tank 9 and the lower part of the return liquid sedimentation tank 13. A circulating pump II 12 is provided in the return liquid sedimentation tank 13 and is connected to the return liquid pipe 11 by a through threaded connection. A grid filter plate 14 is provided above the circulating pump II 12 and is fixedly connected to the inner wall of the return liquid sedimentation tank 13. The mixing tank 9 is equipped with a grid cover 8, the lower end of the grid cover 8 is equipped with a stirring shaft 10, the upper end of the grid cover 8 is equipped with a stirring pump 6 that is splined and fixed to the stirring shaft 10, the grid cover 8 is equipped with a circulating liquid pump I5, the circulating liquid pump I5 is connected to the silicon wafer grinding assembly 1 with a grinding liquid inlet pipe 2, and the grinding liquid inlet pipe 2 is equipped with a replenishment pipe 4 that is connected to the grinding liquid inlet pipe 2.

[0029] A method for recovering and supplying polishing slurry in silicon wafer processing includes the following steps:

[0030] Step 1: Add 60L of pure water to the mixing tank 9, install the grid tank cover 8, and turn on the circulating pump I5 and the mixing pump 6.

[0031] Step 2: Add 7L of weak alkaline dispersant stock solution to the mixing tank and stir for 22 minutes.

[0032] Step 3: Add 40 kg of the Al2O3 and zirconate mixture to the mixing tank and stir continuously.

[0033] Step 4: Set the power of the stirring pump 6 to 0.6KW and the power of the circulating pump I5 to 1.25KW.

[0034] Step 5: Manually place the silicon wafer into the customized carrier hole on the fixed plate of the silicon wafer grinding assembly 1, start the silicon wafer grinding assembly 1, and begin the grinding process. Each round of processing takes about 10 minutes. After the target is achieved, remove the processed silicon wafer and continue to place the next batch of silicon wafers.

[0035] The silicon wafer polishing assembly 1 includes a carrier 19, on which 30 silicon wafers 18 are fixed with the carrier 19 by a snap-fit ​​fixture. An upper polishing disc 16 is provided above the carrier 19, and a thickness probe (17) is provided inside the upper polishing disc 16. A lower polishing disc 20 is provided at the lower end of the carrier 19, and 30 polishing slurry channels 15 are provided on the lower polishing disc 20, which are connected to the polishing slurry inlet pipe 2. The polishing slurry channels 15 are respectively connected to the silicon wafers 18.

[0036] A grinding return liquid tray 21 is provided between the lower grinding disc 20 and the return liquid sedimentation tank 13. The upper end of the grinding return liquid tray 21 is provided with three return liquid ring grooves 23. The grinding return liquid tray 21 is provided with a return liquid channel 22 that is connected to the return liquid ring grooves 23 and the return liquid sedimentation tank 13.

[0037] Step 6: After the grinding liquid in the mixing tank 9 has been used multiple times, drain it and clean the mixing tank 9.

[0038] Lifting guide rails 7 are provided between the two sides of the grid cover 8 and the inner wall of the mixing tank 9. Lifting cylinders 3 are provided on both sides of the upper end of the grid cover 8, which slide along the lifting guide rails 7. The processing time for each round of silicon wafer processing is 10 minutes. The grid cover 8 is raised by the lifting cylinders 3, and it is raised by 2mm for each processing round. When the circulating liquid pump I5 can no longer draw polishing liquid, the circulating polishing liquid can no longer be used and needs to be drained and the mixing tank 9 cleaned. At the same time, the lifting cylinders 3 are reset to the lowest initial position.

[0039] In summary, this silicon wafer processing slurry recycling and supply method features a compact structure and good operational stability. It solves the problem of maintaining the overall density of the slurry supplied to the processing section. It also improves the entire slurry recycling process and reduces the risk of surface scratches.

[0040] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A method for recovering and supplying a silicon wafer processing slurry, characterized by comprising: The assembly includes a silicon wafer grinding assembly (1), a return liquid sedimentation tank (13) connected to the silicon wafer grinding assembly (1) by a pipeline at the lower end of the assembly, a stirring tank (9) on the side of the assembly, a return liquid pipe (11) between the upper end of the stirring tank (9) and the lower part of the return liquid sedimentation tank (13), a circulating pump II (12) connected to the return liquid pipe (11) by a threaded connection in the return liquid sedimentation tank (13), a grid cover (8) on the stirring tank (9), a stirring shaft (10) at the lower end of the grid cover (8), a stirring pump (6) connected to the stirring shaft (10) by a splined snap ring at the upper end of the grid cover (8), a circulating pump I (5) on the grid cover (8), and a grinding liquid inlet pipe (2) between the circulating pump I (5) and the silicon wafer grinding assembly (1). ​ A method for recovering and supplying polishing slurry in silicon wafer processing includes the following steps: Step 1: Add 60L of pure water to the mixing tank (9), install the grid tank cover (8), and turn on the circulating pump I (5) and the mixing pump (6). Step 2: Add 5-10L of weak alkaline dispersant stock solution to the mixing tank and stir for 15-30 minutes; Step 3: Add 30-50 kg of the Al2O3 and zirconate mixture to the mixing tank and stir continuously; Step 4: Set the power of the stirring pump (6) to 0.4-0.8KW and the power of the circulating pump I (5) to 1-1.5KW; Step 5: Manually place the silicon wafer into the customized carrier hole on the fixed plate of the silicon wafer grinding assembly (1), start the silicon wafer grinding assembly (1), and start the grinding process. Each round of processing takes about 10 minutes. After the target is achieved, take out the processed silicon wafer and continue to place the next batch of silicon wafers. Step 6: After the grinding liquid in the mixing tank (9) has been used multiple times, drain it and clean the mixing tank (9).

2. The method according to claim 1, wherein: The silicon wafer polishing assembly (1) includes a carrier (19), on which a plurality of silicon wafers (18) are fixed in a clamping fixture. An upper polishing disc (16) is provided above the carrier (19), and a thickness probe (17) is provided inside the upper polishing disc (16). A lower polishing disc (20) is provided at the lower end of the carrier (19), and a plurality of polishing slurry channels (15) are provided on the lower polishing disc (20) and connected to the polishing slurry inlet pipe (2). The polishing slurry channels (15) are respectively connected to the silicon wafers (18).

3. The method according to claim 2, wherein: A grinding return liquid tray (21) is provided between the lower grinding disc (20) and the return liquid sedimentation tank (13). The upper end of the grinding return liquid tray (21) is provided with several return liquid ring grooves (23). The grinding return liquid tray (21) is provided with a return liquid channel (22) that is connected to the return liquid ring grooves (23) and the return liquid sedimentation tank (13).

4. The method according to claim 1, wherein: The grid cover (8) is provided with lifting guide rails (7) on both sides and the inner wall of the mixing tank (9). The upper end of the grid cover (8) is provided with lifting cylinders (3) that slide along the lifting guide rails (7).

5. The method according to claim 4, wherein: The processing time for each round of silicon wafer processing is 10 minutes. The grid barrel cover (8) is raised by the lifting cylinder (3) by 2mm for each round of processing. When the circulating pump I (5) cannot draw the polishing liquid, the circulating polishing liquid can no longer be used and needs to be drained and the mixing barrel (9) cleaned. At the same time, the lifting cylinder (3) is reset to the lowest initial position.

6. The method of claim 1, wherein: The circulating pump II (12) is provided with a grid filter plate (14) fixedly connected to the inner wall of the return sedimentation tank (13).

7. The method of claim 1, wherein: The grinding slurry inlet pipe (2) is provided with a replenishment pipe (4) that is connected to the grinding slurry inlet pipe (2).

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