BOE etching solution life-prolonging circulating device

Abstract

The utility model is applicable to the technical field of manufacturing of semiconductors and electronic glass, and provides a BOE etching liquid life-prolonging circulating device, which comprises a reaction tank used for carrying out etching reaction on SiO2-containing materials; the treatment tank is used for carrying out sedimentation treatment on large suspended particles, the treatment tank is mounted on one side of the reaction tank, an overflow pipe is arranged at the upper end between the reaction tank and the treatment tank, and the reaction tank and the treatment tank are fixedly communicated through the overflow pipe; suspended particles in the etching solution are removed through the treatment tank with the three-stage gradient and the filter, the particles are prevented from being adsorbed on the surface of a silicon wafer to affect the corrosion area, the activity of the etching solution is improved, the etching consistency is guaranteed, the BOE etching solution with the suspended particles removed is recycled through the circulating pump, the service life of the BOE etching solution is prolonged, and the service life of the BOE etching solution is prolonged. And the treatment cost of the waste liquid and the pressure of environment-friendly and compliant discharge are reduced.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor and electronic glass manufacturing technology, and in particular to a BOE etching solution life extension and circulation device. Background Technology

[0002] BOE (Buffered Oxide Etch) is a buffered oxide etchant. It is composed of a 49% aqueous solution of hydrofluoric acid and an aqueous solution of ammonium fluoride in a specific ratio. A 6:1 BOE etching solution means that the mixture consists of 49% HF aqueous solution and 40% NH4F aqueous solution in a volume ratio of 1:6. The etching rate is approximately 10 nm per second. HF is the main etchant, while NH4F is used as a buffer.

[0003] When BOE corrodes materials containing SiO2, the following reaction occurs:

[0004] SiO2 + 6HF → H2SiF6 + 2H2O

[0005] Simultaneously, metal oxides such as Al2O3 and Pb2O5 are stripped off to form suspended particles of 200-500nm.

[0006] In traditional processes, these particles adsorb onto the silicon wafer surface to form a mask layer, reducing the effective etching area, consuming free HF, and causing a decrease in solution activity. The waste liquid after a single use of the etching solution presents problems such as high treatment costs and significant environmental compliance pressure. Utility Model Content

[0007] This invention provides a BOE etching solution life extension and recycling device, which aims to solve the problems in traditional processes where these particles adsorb onto the silicon wafer surface to form a mask layer, reducing the effective etching area, consuming free HF, leading to a decrease in solution activity, and the waste liquid after a single use of the etching solution has high treatment costs and high environmental compliance pressure.

[0008] This invention is implemented as follows: a BOE etching solution life-extending circulation device includes: a reaction tank for etching SiO2-containing materials; a treatment tank for settling large suspended particles, the treatment tank being installed on one side of the reaction tank, with an overflow pipe at the upper end between the reaction tank and the treatment tank, the two being fixedly connected through the overflow pipe; a circulation pump for circulating the etching solution after settling in the treatment tank to the reaction tank, the circulation pump having an inlet pipe and an outlet pipe respectively, the circulation pump being sequentially connected to the treatment tank and the reaction tank through the inlet pipe and the outlet pipe; and a filter installed on the outlet pipe for filtering the etching solution transported by the outlet pipe.

[0009] Preferably, the lining of the reaction tank is made of polytetrafluoroethylene, and the tank wall integrates a constant temperature heating module.

[0010] The beneficial effects of adopting the above-mentioned further solutions are: the reaction tank material is resistant to HF corrosion, which improves the service life of the equipment; the constant temperature heating module is used to maintain the reaction tank 1 in a constant temperature environment of 35±0.5℃, which improves the reaction efficiency.

[0011] Preferably, the interior of the reaction tank is provided with a flow equalization plate, which has a porous honeycomb structure.

[0012] The beneficial effect of adopting the above-mentioned further solution is to improve etching uniformity.

[0013] Preferably, the treatment tank has two sets of baffles of decreasing length arranged sequentially along the fluid direction, which divide the treatment tank into three-stage settling chambers of decreasing height.

[0014] The beneficial effect of adopting the above-mentioned further scheme is that sequential sedimentation treatment of suspended particles can effectively improve the particle removal rate.

[0015] Preferably, the circulating pump is a magnetically driven pump, and the pump body is made of a material resistant to HF corrosion.

[0016] The beneficial effects of adopting the above-mentioned further solutions are: the pump body is made of HF corrosion-resistant material, which improves the service life of the equipment.

[0017] Preferably, the filter is a ceramic membrane filter with a filter accuracy of 0.1 μm.

[0018] The beneficial effect of adopting the above-mentioned further solution is to improve the etching effect of the etching solution.

[0019] Preferably, it further includes: a concentration control mechanism, wherein the concentration control mechanism includes an online density meter and a concentrated HF storage tank connected to the reaction tank.

[0020] The benefits of adopting the above-mentioned further solutions are: ensuring etching effect and improving BOE lifespan.

[0021] Compared with the prior art, the beneficial effects of this utility model are as follows: The BOE etching solution life extension circulation device of this utility model removes suspended particles in the etching solution by setting a three-level gradient treatment tank and filter, preventing particles from adsorbing on the silicon wafer surface and affecting the etching area, improving the activity of the etching solution, ensuring etching consistency, and by setting a circulation pump to circulate the BOE etching solution after removing suspended particles, the service life of the BOE etching solution is improved, and the waste liquid treatment cost and environmental compliance emission pressure are reduced. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the structure of this utility model.

[0023] In the diagram: 1. Reaction tank; 2. Processing tank; 3. Overflow pipe; 4. Circulation pump; 5. Inlet pipe; 6. Outlet pipe; 7. Filter; 8. Flow equalization plate; 9. Baffle plate; 10. Concentration control mechanism. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0025] Please see Figure 1 This utility model provides a technical solution for a BOE etching solution life extension and circulation device: a BOE etching solution life extension and circulation device, comprising:

[0026] Reaction tank 1 is used for etching reaction of SiO2-containing materials;

[0027] Treatment tank 2 is used to settle large suspended particles. Treatment tank 2 is installed on one side of reaction tank 1. An overflow pipe 3 is provided at the upper end between reaction tank 1 and treatment tank 2. The two are fixedly connected through the overflow pipe 3.

[0028] The circulating pump 4 is used to circulate the etching solution after sedimentation treatment in the treatment tank 2 to the reaction tank 1. The inlet and outlet ends of the circulating pump 4 are respectively equipped with an inlet pipe 5 and an outlet pipe 6. The circulating pump 4 is connected to the treatment tank 2 and the reaction tank 1 in sequence through the inlet pipe 5 and the outlet pipe 6.

[0029] Filter 7 is installed on the liquid outlet pipe 6 and is used to filter the etching solution transported by the liquid outlet pipe 6.

[0030] In this embodiment, BOE etching solution is added to the reaction tank 1, where it etches the SiO2-containing material. The suspended particles generated during the reaction flow into the treatment tank 2 through the overflow pipe 3. The treatment tank 2 performs a three-stage gradient sedimentation of the suspended particles. The sedimented etching solution is then transported back to the reaction tank 1 by the circulation pump 4, enabling the recycling of the etching solution. The etching solution in the delivery system is filtered by the filter 7. By using the three-stage gradient treatment tank 2 and the filter 7 to remove suspended particles from the etching solution, the particles are prevented from adsorbing onto the silicon wafer surface, affecting the etching area. This improves the activity of the etching solution and ensures etching consistency. The circulation pump 4 allows for the recycling of the BOE etching solution after removing suspended particles, increasing the service life of the BOE etching solution and reducing the cost of waste liquid treatment and the pressure of environmental compliance.

[0031] Furthermore, the lining of reaction tank 1 is made of polytetrafluoroethylene, and the tank wall integrates a constant temperature heating module.

[0032] In this embodiment, the lining of the reaction tank 1 is made of polytetrafluoroethylene, which is resistant to HF corrosion, thus improving the service life of the equipment, eliminating metal ion contamination, and increasing the chip yield. By integrating a constant temperature heating module into the tank wall of the reaction tank 1, the reaction tank 1 is kept at a constant temperature of 35±0.5℃, thereby improving the reaction efficiency.

[0033] Typically, the interior of the reaction tank 1 is equipped with a flow equalization plate 8, which has a porous honeycomb structure.

[0034] In this embodiment, by providing a flow equalization plate 8 at the bottom of the reaction tank 1, the liquid loss delivered by the circulating pump 8 is dispersed and evenly distributed through the porous honeycomb structure flow equalization plate 8, thereby improving the etching uniformity.

[0035] Specifically, the treatment tank 2 is equipped with two sets of baffles 9 of decreasing length in sequence along the fluid direction, which divide the treatment tank 2 into three-stage settling chambers of decreasing height.

[0036] In this embodiment, by providing two partitions 9 with decreasing lengths inside the treatment tank 2, the treatment tank 2 is divided into three settling chambers with decreasing heights. The height of the partitions 9 closest to the overflow pipe 3 is lower than the height of the overflow port, which facilitates the flow of suspended particles from the overflow pipe 3 into the adjacent settling chamber for primary settling. Unsettled suspended particles flow through the partitions 9 into the next settling chamber for secondary settling. By sequentially settling the suspended particles, the particle removal rate can be effectively improved.

[0037] In addition, the circulating pump 4 is a magnetically driven pump, and the pump body is made of HF corrosion-resistant material.

[0038] In this embodiment, the circulating pump 4 is configured as a magnetically driven pump with a flow rate of 5 m³ / s. 3 / h, made of HF corrosion-resistant material, improves the service life of the equipment.

[0039] Additionally, filter 7 is a ceramic membrane filter with a filter accuracy of 0.1μm.

[0040] In this embodiment, a ceramic membrane filter with a filter accuracy of 0.1 μm is provided. When used in conjunction with the treatment tank 2, the particle removal rate is >99.7%, which improves the etching effect of the etching solution.

[0041] It should be noted that the concentration control mechanism 10 includes an online density meter and a concentrated HF storage tank connected to the reaction tank 1.

[0042] In this embodiment, a concentration control mechanism 10 is provided, and the HF concentration in the reaction tank 1 is monitored in real time by an online density meter (accuracy ±0.5wt%). Concentrated HF (40%) is dynamically added to the reaction tank 1 through a concentrated HF storage tank according to the etching amount, thereby improving the activity of the etching solution, ensuring etching consistency, ensuring etching effect, and improving the service life of BOE.

[0043] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A BOE etching solution life extension and circulation device, characterized in that, include: The reaction tank (1) is used to perform an etching reaction on SiO2-containing materials; The treatment tank (2) is used to settle large suspended particles. The treatment tank (2) is installed on one side of the reaction tank (1). An overflow pipe (3) is provided at the upper end between the reaction tank (1) and the treatment tank (2). The two are fixedly connected through the overflow pipe (3). A circulation pump (4) is used to circulate the etching solution after sedimentation treatment in the treatment tank (2) to the reaction tank (1). The circulation pump (4) is provided with an inlet pipe (5) and an outlet pipe (6) at its inlet and outlet ends, respectively. The circulation pump (4) is connected to the treatment tank (2) and the reaction tank (1) in sequence through the inlet pipe (5) and the outlet pipe (6). A filter (7) is provided on the outlet pipe (6) for filtering the etching solution transported by the outlet pipe (6).

2. The BOE etching solution life extension circulation device according to claim 1, characterized in that: The reaction tank (1) is lined with polytetrafluoroethylene and the tank wall is integrated with a constant temperature heating module.

3. The BOE etching solution life extension circulation device according to claim 1, characterized in that: The reaction tank (1) is equipped with a flow equalization plate (8), which has a porous honeycomb structure.

4. The BOE etching solution life extension and circulation device according to claim 1, characterized in that: The treatment tank (2) has two sets of baffles (9) with decreasing lengths arranged sequentially along the fluid direction. The baffles (9) divide the treatment tank (2) into three-stage settling chambers with decreasing heights.

5. The BOE etching solution life extension circulation device according to claim 1, characterized in that: The circulating pump (4) is a magnetically driven pump, and the pump body is made of HF corrosion resistant material.

6. The BOE etching solution life extension and circulation device according to claim 1, characterized in that: The filter (7) is a ceramic membrane filter with a filter accuracy of 0.1 μm.

7. The BOE etching solution life extension circulation device according to claim 1, characterized in that: Also includes: Concentration control mechanism (10), the concentration control mechanism (10) includes an online density meter and a concentrated HF storage tank connected to the reaction tank (1).

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