Crystallization and purification device for electronic-grade phosphoric acid

Abstract

The utility model discloses a crystallization and purification device for electronic grade phosphoric acid, which comprises a crystallizer, a bottom outlet of the crystallizer is connected with a feed port of a centrifugal machine through a pipeline, a discharge port of the centrifugal machine is connected with a feed port of a finished product tank through a crystal conveying pipeline, and a liquid outlet of the centrifugal machine is connected with an inlet of a residual liquid tank through a residual liquid conveying pipeline. An inlet of the crystallizer is connected with the raw material tank through a feeding pipeline, a heater is arranged in the finished product tank, a liquid return port of the finished product tank is connected with a feeding port of the crystallizer through a liquid return pipeline, and a sampling detection pipeline is arranged on one side of the finished product tank; the device can further remove mother liquor mingled in phosphoric acid crystals and remove impurity ions in phosphoric acid, so that the quality of phosphoric acid products is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic-grade phosphoric acid production, in particular to a crystallization and purification device for electronic-grade phosphoric acid. Background Art

[0002] In recent years, with the rapid development of the microelectronics industry, China has gradually become the world's largest LCD industry base. Electronic-grade phosphoric acid is one of the most technologically advanced products in the phosphorus chemical industry. It is an irreplaceable ultra-pure chemical reagent in the chip manufacturing industry. As a wet cleaning agent and etching agent, it is widely used in semiconductor fields such as integrated circuits, thin-film liquid crystal displays, and silicon wafer lithography. At the same time, with the continuous breakthroughs in chip technology and the emergence and application of 3D-NAND technology, the semiconductor industry's quality requirements for electronic-grade phosphoric acid are also constantly increasing.

[0003] At present, electronic-grade phosphoric acid obtained through the traditional thermal phosphoric acid process can basically meet the needs of most current semiconductor production lines. However, for the production of semiconductor components with higher processes and the rapid development of production technology, the semiconductor industry's quality requirements and demand for electronic-grade phosphoric acid are constantly increasing. If a large number of metal ions exist in fine circuits, it will not only cause changes in the resistivity of integrated circuits, a decrease in the minority carrier lifetime, and microplasma breakdown, but also lead to a decrease in the yield, electrical performance and reliability of integrated circuits, causing large-scale circuit disconnection and scrapping, so extremely high requirements are placed on the quality of electronic-grade phosphoric acid. Therefore, with the booming domestic chip industry, it is imperative to develop a simple method for the crystallization and purification of electronic-grade phosphoric acid that is suitable for large-scale industrial production. Summary of the invention

[0004] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide a crystallization and purification device for electronic grade phosphoric acid to further remove the mother liquor mixed in the phosphoric acid crystals and remove the impurity ions in the phosphoric acid, so as to effectively improve the quality of the phosphoric acid product.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is: a crystallization and purification device for electronic grade phosphoric acid, comprising a crystallizer, wherein the bottom outlet of the crystallizer is connected to the feed port of a centrifuge through a pipeline, the discharge port of the centrifuge is connected to the feed port of a finished product tank through a crystal conveying pipeline, the liquid outlet of the centrifuge is connected to the inlet of the residual liquid tank through a residual liquid conveying pipeline, the inlet of the crystallizer is connected to the raw material tank through a feed pipeline, a heater is provided in the finished product tank, the liquid return port of the finished product tank is connected to the feed port of the crystallizer through a liquid return pipeline, and a sampling detection pipeline is provided on one side of the finished product tank.

[0006] Preferably, the liquid outlet of the centrifuge is also connected to the raw material tank via a spare pipeline, and a valve is provided on the spare pipeline.

[0007] Preferably, a first delivery pump is provided on the liquid return pipeline.

[0008] Preferably, a second delivery pump is provided on the feed pipeline.

[0009] Preferably, a stirring device is provided inside the crystallizer, and a cooling water jacket is provided on the surface of the crystallizer.

[0010] Beneficial effects of the utility model:

[0011] The utility model can further remove the mother liquor mixed in the phosphoric acid crystals and remove the impurity ions in the phosphoric acid, thereby effectively improving the quality of the phosphoric acid product. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of a crystallization and purification device for electronic grade phosphoric acid. DETAILED DESCRIPTION

[0013] The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

[0014] like Figure 1 As shown, a crystallization and purification device for electronic grade phosphoric acid comprises a crystallizer 1, wherein the bottom outlet of the crystallizer 1 is connected to the feed port of a centrifuge 2 through a pipeline, the discharge port of the centrifuge 2 is connected to the feed port of a finished product tank 4 through a crystal conveying pipeline 3, the liquid outlet of the centrifuge 2 is connected to the inlet of a residual liquid tank 6 through a residual liquid conveying pipeline 5, the inlet of the crystallizer 1 is connected to a raw material tank 8 through a feed pipeline 7, a heater is provided in the finished product tank 4, the liquid return port of the finished product tank 4 is connected to the feed port of the crystallizer 1 through a liquid return pipeline 9, and a sampling detection pipeline 10 is provided on one side of the finished product tank 4.

[0015] Preferably, the liquid outlet of the centrifuge 2 is also connected to the raw material tank 8 through a spare pipeline 11, and a valve 12 is provided on the spare pipeline 11. With this design, when the material in the residual liquid tank 6 is at a full liquid level and the material in the crystallizer 1 is crystallized and needs to be discharged immediately, the valve 12 on the spare pipeline 11 can be opened to allow the material to be temporarily stored in the raw material tank 8. In addition, the design of the spare pipeline 11 can also allow the residual liquid generated after centrifugal separation to be passed into the crystallizer 11 for another crystallization process, thereby improving the utilization rate of the residual liquid.

[0016] Preferably, a first delivery pump 9.1 is provided on the liquid return pipeline 9. The first delivery pump 9.1 can pump the material in the finished product tank 4 back to the crystallizer 1 for recrystallization.

[0017] Preferably, a second delivery pump 7.1 is provided on the feed pipeline 7. The second delivery pump 7.1 can pump the material in the raw material tank 8 into the crystallizer 1 for crystallization.

[0018] Preferably, a stirring device 1.1 is provided inside the crystallizer 1, and a cooling water jacket 1.2 is provided on the surface of the crystallizer 1. The cooling water jacket 1.2 can cool the material in the crystallizer 1 to promote its crystallization process.

[0019] The working principle of this embodiment is as follows:

[0020] S1. First, the raw material phosphoric acid is pumped from the raw material tank 8 into the crystallizer 1, the stirring device is turned on, and chilled water is introduced into the cooling water jacket 1.2 to cool the phosphoric acid for pre-cooling treatment;

[0021] S2, adding seed crystals and mixing with the pre-cooled phosphoric acid obtained in step S1, cooling and stirring to crystallize to obtain crude crystals;

[0022] S3, placing the crude crystals obtained in step S2 into centrifuge 2 from the bottom of the crystallizer, and starting washing to perform solid-liquid separation to obtain phosphoric acid residual liquid and phosphoric acid crystals;

[0023] S4. The crystals obtained in step S3 enter the finished product tank and are melted by heating or dissolved by adding ultrapure water to obtain a high-purity phosphoric acid product.

[0024] S5. Sample the material in the finished product tank 4 through the sampling test pipeline 10. If the impurities are still found to exceed the standard after the test, the material in the finished product tank 4 is pumped back into the crystallizer 1 through the return liquid pipeline 9 for crystallization until the sampling test results are qualified.

[0025] Preferably, the phosphoric acid concentration in step S1 is required to be greater than 85wt%, for example, it can be 85wt%, 85.7wt%, 86wt%, 87wt% or 88wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the precooling treatment time in step S1 is 30-60 min, for example, 30 min, 40 min, 50 min or 60 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the temperature of the precooled phosphoric acid in step S1 is 15-28°C, for example, 15°C, 18°C, 20°C or 27°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the cooling rate of the cooling crystallization in step S2 is 2-6°C / h, for example, 2°C / h, 3°C / h, 4°C / h or 5°C / h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the cooling time of the cooling crystallization in step S2 is 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours or 3 hours, but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0030] Preferably, in step S3, the crude crystals obtained are washed with the product or ultrapure water as a washing liquid, and the flow rate of the washing liquid is controlled at 0.2-0.5 m³ / h, for example, it can be 0.2 m³ / h, 0.25 m³ / h, 0.3 m³ / h or 0.45 m³ / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the electronic grade phosphate metal ion content of the finished product in step S4 can reach less than 10 ppb. If the impurities are found to exceed 10 ppb after detection in step S5, the material in the finished product tank 4 is pumped back to the crystallizer 1 through the return line 9 for crystallization.

[0032] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A crystallization and purification device for electronic grade phosphoric acid, comprising a crystallizer (1), wherein the bottom outlet of the crystallizer (1) is connected to the feed port of a centrifuge (2) via a pipeline, the discharge port of the centrifuge (2) is connected to the feed port of a finished product tank (4) via a crystal delivery pipeline (3), the liquid outlet of the centrifuge (2) is connected to the inlet of a residual liquid tank (6) via a residual liquid delivery pipeline (5), and the inlet of the crystallizer (1) is connected to a raw material tank (8) via a feed pipeline (7), characterized in that: A heater is provided in the finished product tank (4); a liquid return port of the finished product tank (4) is connected to a feed port of the crystallizer (1) via a liquid return pipeline (9); and a sampling detection pipeline (10) is provided on one side of the finished product tank (4).

2. The crystallization and purification device for electronic grade phosphoric acid according to claim 1, characterized in that: The liquid outlet of the centrifuge (2) is also connected to the raw material tank (8) via a spare pipeline (11), and a valve (12) is provided on the spare pipeline (11).

3. The crystallization and purification device for electronic grade phosphoric acid according to claim 1, characterized in that: The liquid return pipeline (9) is provided with a first delivery pump (9.1).

4. The crystallization and purification device for electronic grade phosphoric acid according to claim 1, characterized in that: The feed pipeline (7) is provided with a second delivery pump (7.1).

5. The crystallization and purification device for electronic grade phosphoric acid according to claim 1, characterized in that: A stirring device (1.1) is provided inside the crystallizer (1), and a cooling water jacket (1.2) is provided on the surface of the crystallizer (1).

Images