Acid mixing system for improving DHF concentration stability

Abstract

The utility model provides an acid mixing system for improving DHF concentration stability, which comprises a mixing tank used for mixing a first solution and a second solution; one end of the first supply pipeline is connected with a first solution source, the other end of the first supply pipeline is connected to the mixing tank, a first valve and a first flow meter are arranged on the first supply pipeline, and the first solution flows through the first flow meter and then flows through the first valve; one end of the second supply pipeline is connected with a second solution source, the other end of the second supply pipeline is connected to the mixing tank, and a second valve and a second flow meter are arranged on the second supply pipeline; and the feedback control module is used for receiving a flow signal monitored by the first flow meter and controlling the opening degree of the first valve according to the flow signal. The feedback control module receives a flow signal of the first flow meter and controls the opening degree of the first valve, so that the flow of the first solution is accurately regulated and controlled, the mixing proportion change is reduced, and the DHF concentration stability is remarkably improved.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing equipment, and in particular to a mixed acid system for improving the stability of DHF concentration. Background Technology

[0002] In the field of semiconductor manufacturing equipment, the CDS-DHF (Diluted Hydrofluoric Acid Supply System) of the ACM Ultra C SAPS V model plays a crucial role in meeting the hydrofluoric acid solution concentrations required for different processes. Currently, this system obtains HF solutions of varying concentrations by mixing deionized water (DIW) with a 49% concentration hydrofluoric acid (HF) solution in different volume ratios. However, in existing technologies, the flow rate is crudely regulated solely by PV (pneumatic valves) in individual pipelines, and control is based only on preset valve opening parameters. This control method has significant drawbacks. Due to the lack of a real-time flow feedback mechanism, it is impossible to accurately monitor the flow rate changes of DIW and 49% HF solutions during actual delivery, making it difficult to ensure flow stability and easily leading to errors in HF solution concentration, which in turn affects the manufacturing quality of semiconductor devices. Utility Model Content

[0003] To address all or part of the problems in the prior art, this invention provides a mixed acid system for improving the stability of DHF concentration. By receiving the flow signal from the first flow meter and controlling the opening of the first valve through a feedback control module, the flow rate of the first solution can be precisely controlled, reducing changes in the mixing ratio and significantly improving the stability of DHF concentration.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A mixed acid system for improving the stability of DHF concentration includes:

[0006] A mixing vessel for mixing a first solution and a second solution;

[0007] A first supply pipeline has one end connected to a first solution source and the other end connected to the mixing tank. The first supply pipeline is equipped with a first valve and a first flow meter. The first solution first flows through the first flow meter and then through the first valve.

[0008] The second supply pipeline has one end connected to the second solution source and the other end connected to the mixing tank. The second supply pipeline is equipped with a second valve and a second flow meter.

[0009] The feedback control module receives the flow signal monitored by the first flow meter and controls the opening degree of the first valve according to the flow signal.

[0010] The feedback control module receives the flow signal monitored by the second flow meter and controls the opening degree of the second valve according to the flow signal.

[0011] The first solution is deionized water, and the second solution is a 49% hydrofluoric acid solution.

[0012] The first valve is a pneumatic valve. Compressed air is connected to the drive end of the first valve through a pipeline. The opening degree of the first valve is controlled by adjusting the pressure of the compressed air.

[0013] It also includes a main pipeline, with the first supply pipeline and the second supply pipeline connected to one end of the main pipeline and the other end of the main pipeline connected to the mixing tank.

[0014] A third valve is installed on the main pipeline.

[0015] It also includes a first discharge pipeline, one end of which is connected to the mixing tank and the other end of which is connected to the collection device.

[0016] A fourth valve is installed on the first discharge pipeline.

[0017] It also includes a second discharge pipeline, one end of which is connected to the main pipeline and the other end of which is connected to the first discharge pipeline.

[0018] A fifth valve is installed on the second discharge pipeline. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a mixed acid system for improving the stability of DHF concentration according to an embodiment of the present invention.

[0021] Figure 2 Experimental curves for a mixed acid system that improves the stability of DHF concentration without using the present invention.

[0022] Figure 3 Experimental curves for using a mixed acid system that improves the stability of DHF concentration provided by this invention.

[0023] Reference numerals: 1. Mixing tank; 2. First supply line; 201. First valve; 2011. Gas line; 202. First flow meter; 3. Second supply line; 4. Main line; 5. First discharge line; 6. Second discharge line. Detailed Implementation

[0024] The technical solutions in specific embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] The implementation of this utility model will be described in detail below with reference to specific embodiments.

[0026] In this embodiment of the utility model, in conjunction with reference to the reference Figures 1 to 3 As shown, a mixed acid system designed to improve the concentration stability of DHF (diluted hydrofluoric acid) is provided. The system mainly consists of a mixing tank 1, a first supply pipeline 2, a second supply pipeline 3, and a feedback control module. The mixing tank 1, as the core component, is used to thoroughly mix a first solution and a second solution to obtain a mixed solution meeting specific concentration requirements. One end of the first supply pipeline 2 is connected to the first solution source, and the other end is connected to the mixing tank 1, allowing the first solution to flow smoothly into the mixing tank 1. A first flow meter 202 and a first valve 201 are sequentially installed on the first supply pipeline 2 along the flow direction of the first solution. After entering the first supply pipeline 2, the first solution first flows through the first flow meter 202, which monitors the flow rate of the first solution in real time and outputs the monitored flow data as an electrical signal. Subsequently, the first solution flows through the first valve 201, which is used to regulate the flow rate of the first solution. One end of the second supply pipeline 3 is connected to the second solution source, and the other end is connected to the mixing tank 1. A second valve and a second flow meter are installed on the second supply pipeline 3. The second flow meter is used to monitor the flow rate of the second solution in real time, while the second valve can adjust the flow rate of the second solution according to actual needs, so as to ensure that the second solution enters the mixing tank 1 at a suitable flow rate.

[0027] The feedback control module is connected to the first flow meter 202 via a signal line and can receive the flow signal monitored by the first flow meter 202. This module compares and analyzes the received actual flow signal with a preset target flow rate, and then generates a corresponding control signal based on the analysis results. This signal is then transmitted to the first valve 201 to achieve precise control of the opening of the first valve 201, ensuring that the flow rate of the first solution remains stable near the target value, thereby effectively improving the stability of the DHF concentration. In other specific embodiments, the second valve and the second flow meter can also be incorporated into the feedback control system. The second flow meter transmits the real-time monitored flow rate signal of the second solution to the feedback control module. The feedback control module compares and analyzes this actual flow rate signal with the preset target flow rate of the second solution, generates a control signal based on the analysis results, and transmits it to the second valve to precisely adjust the opening of the second valve, so that the flow rate of the second solution also remains stable near the target value. Through this dual feedback control mechanism, the accuracy of the mixing ratio of the two solutions is further improved.

[0028] In this embodiment, the first solution is specifically deionized water (DIW), and the second solution is specifically a 49% hydrofluoric acid (HF) solution. The two are mixed in a preset ratio using this mixed acid system to prepare a DHF solution of the target concentration. The first valve 201 employs a pneumatic valve structure, specifically a HICV high-precision control valve. The drive end of this pneumatic valve is connected to an external compressed air source via a gas pipeline 2011. Compressed air is delivered to the actuator (such as a cylinder or diaphragm assembly) of the pneumatic valve through the pipeline. The feedback control module adjusts the pressure of the compressed air input to the drive end of the pneumatic valve to achieve linear control of the valve core displacement, thereby precisely adjusting the opening of the first valve 201 to stabilize the deionized water flow rate at the target value. This control method utilizes the proportional characteristics of gas pressure and valve opening, combined with real-time flow feedback from the first flow meter 202, to form a closed-loop control circuit, effectively improving the control accuracy of the deionized water flow rate during the mixed acid process, thus ensuring the stability of the DHF solution concentration. In other specific embodiments, the first valve 201 is not limited to a pneumatic valve, but can also be other types of valves to achieve precise adjustment of the flow rate of the first solution.

[0029] This utility model's acid mixing system also includes a main pipeline 4, a first discharge pipeline 5, and a second discharge pipeline 6 to improve system functionality and achieve a more efficient and stable acid mixing process. The ends of the first supply pipeline 2 and the second supply pipeline 3 are both connected to the same end of the main pipeline 4, allowing the first solution (e.g., deionized water) and the second solution (e.g., 49% hydrofluoric acid solution) to initially converge within the main pipeline 4. The other end of the main pipeline 4 is connected to the mixing tank 1, allowing the solution to flow smoothly into the mixing tank 1. To precisely control the process of the solution entering the mixing tank 1, a third valve is installed on the main pipeline 4, which can flexibly adjust the on / off state and flow rate of the main pipeline 4 according to actual needs. One end of the first discharge pipeline 5 is connected to the bottom of the mixing tank 1, and the other end is connected to a collection device for timely discharge of waste liquid or excess solution from the mixing tank 1. A fourth valve is installed on the first discharge pipeline 5 to control the discharge of liquid from the mixing tank 1. One end of the second discharge pipeline 6 is connected to the main pipeline 4 before the third valve, and the other end is connected to the first discharge pipeline 5. This connection design allows unstable flow solutions generated momentarily by valve opening or closing in the first supply line 2 and the second supply line 3 to be promptly and effectively channeled into the first discharge line 5 via the second discharge line 6, ultimately flowing into the collection device. This prevents unstable solutions from entering the mixing tank 1 and affecting the stability of the mixed acid concentration. A fifth valve is installed on the second discharge line 6 to control its on / off state.

[0030] In the initial stage of the mixed acid process, the flow rate of the solution in the pipes is unstable due to various factors such as fluid inertia and pressure fluctuations at the moment the valves in the first supply line 2 and the second supply line 3 open. If this unstable solution is directly introduced into the mixing tank 1 at this time, it will adversely affect the accuracy of the final mixed solution concentration, thus reducing product quality. To effectively avoid this problem, the system automatically closes the third valve on the main supply line 4 at the beginning of the process to prevent the unstable solution from flowing into the mixing tank 1. Simultaneously, the fifth valve on the second discharge line 6 and the fourth valve on the first discharge line 5 are opened. The unstable solution in the first supply line 2 and the second supply line 3 will first converge into the main supply line 4, then flow into the first discharge line 5 through the second discharge line 6, and finally into the collection device, thus achieving effective discharge of the unstable solution. During the discharge process, the system continuously monitors the flow rate of the solution in the first supply line 2 and the second supply line 3 in real time. When the flow rate reaches a stable state, i.e., the flow fluctuation range is within a preset reasonable range, the system automatically closes the fifth and fourth valves to stop the discharge of the unstable solution. Subsequently, the third valve is opened to allow the stable first and second solutions to flow smoothly into the mixing tank 1 through the main pipeline 4 for precise mixing, ensuring that the concentration of the mixed solution meets the process requirements.

[0031] Similarly, at the end of the mixed acid process, the flow rate of the solution in the pipes will become unstable again the instant the valves in the first supply line 2 and the second supply line 3 are closed. To prevent the residual unstable solution from affecting the accuracy of the next process, the system will repeat the above operation. That is, the third valve will be closed, and the fifth and fourth valves will be opened to discharge the residual unstable solution in the main pipe 4 to the collection device. After confirming that the solution in the main pipe 4 has been discharged and the flow rate is stable, the fifth and fourth valves will be closed to prepare for the next mixed acid process. Through this precise flow control and discharge operation, the mixed acid system of this invention can effectively improve the stability and accuracy of the mixed solution concentration, ensuring the consistency and reliability of product quality.

[0032] It should be noted that, for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the scope of protection of the claims of this utility model.

Claims

1. A mixed acid system for improving stability of DHF concentration, characterized by, include: Mixing vessel (1) for mixing the first solution and the second solution; The first supply pipeline (2) is connected at one end to the first solution source and at the other end to the mixing tank (1). The first supply pipeline (2) is equipped with a first valve (201) and a first flow meter (202). The first solution first flows through the first flow meter (202) and then through the first valve (201). The second supply pipeline (3) is connected at one end to the second solution source and at the other end to the mixing tank (1). The second supply pipeline (3) is equipped with a second valve and a second flow meter. The feedback control module receives the flow signal monitored by the first flow meter (202) and controls the opening degree of the first valve (201) according to the flow signal.

2. The system of claim 1, wherein, The feedback control module receives the flow signal monitored by the second flow meter and controls the opening degree of the second valve according to the flow signal.

3. The system of claim 1, wherein, The first solution is deionized water, and the second solution is a 49% hydrofluoric acid solution.

4. The system of claim 1, wherein, The first valve (201) is a pneumatic valve. Compressed air is connected to the drive end of the first valve (201) through a gas pipeline (2011). The opening degree of the first valve (201) is controlled by adjusting the pressure of the compressed air.

5. The system of claim 1, wherein, It also includes a main pipeline (4), with the first supply pipeline (2) and the second supply pipeline (3) connected to one end of the main pipeline (4), and the other end of the main pipeline (4) connected to the mixing tank (1).

6. The system of claim 5, wherein, A third valve is installed on the main pipeline (4).

7. The system of claim 5, wherein, It also includes a first discharge pipe (5), one end of which is connected to the mixing tank (1) and the other end is connected to the collection device.

8. The system of claim 7, wherein, A fourth valve is installed on the first discharge pipeline (5).

9. The system of claim 7, wherein, It also includes a second discharge pipe (6), one end of which is connected to the main pipe (4) and the other end is connected to the first discharge pipe (5).

10. The system of claim 9, wherein, A fifth valve is installed on the second discharge pipeline (6).

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