阅读说明：本技术 连续法制备电子级氢氟酸的方法及系统 (Method and system for preparing electronic-grade hydrofluoric acid by continuous method ) 是由 尹光凯 郑昌松 杨坤 于 2020-07-13 设计创作，主要内容包括：本发明属于电子化学品制备技术领域,具体涉及一种连续法制备电子级氢氟酸的方法及系统。方法包括如下步骤：(1)一级精馏：主要去除原料中的重组分杂质及轻组分气相杂质；(2)二级精馏：进一步去除前段精馏未能去除干净的金属离子及杂质；(3)吸收：最大程度的将氟化氢吸收完全,提高氟化氢的利用率；(4)过滤：得到合格的UPSS级氢氟酸水溶液。本发明采用连续性生产方式,原料氟化氢液体不间断地输入一级精馏塔内,超纯水连续不间断地输入吸收塔内,电子级氢氟酸连续不间断地从装置中输出。相较于间歇法生产,本连续法工艺参数稳定,生产效率高,工人操作强度低。(The invention belongs to the technical field of electronic chemical preparation, and particularly relates to a method and a system for preparing electronic-grade hydrofluoric acid by a continuous method. The method comprises the following steps: (1) primary rectification: heavy component impurities and light component gas phase impurities in the raw materials are mainly removed; (2) secondary rectification: further removing metal ions and impurities which cannot be removed by the front-stage rectification; (3) absorption: the hydrogen fluoride is completely absorbed to the maximum extent, and the utilization rate of the hydrogen fluoride is improved; (4) and (3) filtering: obtaining qualified UPSS hydrofluoric acid water solution. The invention adopts a continuous production mode, raw material hydrogen fluoride liquid is uninterruptedly input into the first-stage rectifying tower, ultrapure water is uninterruptedly input into the absorption tower, and electronic-grade hydrofluoric acid is uninterruptedly output from the device. Compared with the batch production method, the continuous production method has stable technological parameters, high production efficiency and low operation intensity of workers.)

1. The method for preparing electronic-grade hydrofluoric acid by a continuous method is characterized by comprising the following steps of:

(1) primary rectification: introducing the hydrogen fluoride liquid after dearsenification into a primary rectifying tower, heating and gasifying the hydrogen fluoride liquid through a primary reboiler, carrying out gas-liquid phase heat transfer, mass transfer and separation on the gasified hydrogen fluoride in the primary rectifying tower, enriching various recombinant separator impurities at the bottom of the tower by utilizing different boiling points of various substances in the hydrogen fluoride, and discharging the impurities into a raffinate tank; the hydrogen fluoride gas after the first-stage purification is condensed into liquid in a first-stage condenser, and the non-condensable gas is discharged into a tail gas treatment system;

(2) secondary rectification: the hydrogen fluoride liquid after the primary rectification enters a secondary rectification tower, is heated and gasified by a secondary reboiler, the gasified hydrogen fluoride is subjected to gas-liquid phase heat transfer, mass transfer and separation in a secondary rectification tower 4, and various ionic impurities which are not removed in the primary rectification are enriched at the bottom of the tower and are discharged into a residue liquid tank; the hydrogen fluoride gas purified again enters a secondary condenser, part of the hydrogen fluoride gas is condensed and flows back to a secondary rectifying tower in the secondary condenser, and the rest hydrogen fluoride gas enters an absorption tower;

(3) absorption: the hydrogen fluoride gas after the secondary rectification enters an absorption tower from the lower part and is absorbed by electronic-grade ultrapure water, absorption liquid is conveyed to the middle part of the absorption tower through a circulating pump and is sprayed downwards by a distributor for absorption, and the top of the tower is absorbed again by the electronic-grade ultrapure water; the hydrogen fluoride gas rises to the top of the tower, the gas phase and the liquid phase are subjected to countercurrent dissolution absorption on the surface of the filler, the absorption dissolution heat is carried out from the liquid phase, enters the bottom of the absorption tower, is conveyed to a cooler through a circulating pump for cooling, enters the tower from the middle of the tower again for spray absorption, and the steps are repeated in a circulating manner;

(4) and (3) filtering: and filtering the hydrofluoric acid aqueous solution discharged from the absorption tower to obtain the qualified UPSS-grade hydrofluoric acid aqueous solution.

2. A continuous process for preparing electronic grade hydrofluoric acid according to claim 1, wherein: in the step (3), an online acid concentration instrument is arranged on the circulating pipe of the absorption liquid.

3. A continuous process for preparing electronic grade hydrofluoric acid according to claim 2, wherein: and (3) continuously inputting the hydrogen fluoride liquid into the first-stage rectifying tower in the step (1), continuously inputting the ultrapure water into the absorption tower in the step (3), and continuously outputting the UPSS hydrofluoric acid from the device in the step (4).

4. A continuous process for preparing electronic grade hydrofluoric acid according to claim 1, wherein: in the step (3), the resistance value of the electronic-grade ultrapure water is more than or equal to 18.2M omega cm.

5. A system for preparing electronic grade hydrofluoric acid by a continuous method is characterized by comprising the following steps:

the primary rectifying tower is used for primary rectification of the raw material hydrogen fluoride liquid;

the primary reboiler is connected with the bottom of the primary rectifying tower and is used for heating and gasifying the raw material hydrogen fluoride liquid;

the primary condenser is connected with the top of the primary rectifying tower and is used for condensing the hydrogen fluoride gas purified and purified by the primary rectifying tower;

the second-stage rectifying tower is connected with the bottom of the first-stage condenser and is used for rectifying the hydrogen fluoride liquid subjected to the first-stage rectification again;

the second-stage reboiler is connected with the bottom of the second-stage rectifying tower and is used for heating and gasifying the hydrogen fluoride liquid after the first-stage rectification;

the secondary condenser is connected with the top of the secondary rectifying tower and is used for condensing part of the hydrogen fluoride gas purified and purified again by the secondary rectifying tower, and the condensed hydrogen fluoride gas reflows into the secondary rectifying tower;

the absorption tower is connected with the bottom of the secondary condenser and is used for absorbing the hydrogen fluoride gas after secondary rectification;

the circulating cooling device is connected with the absorption tower and is used for circulating cooling of absorption liquid in the absorption tower;

a filtering device for filtering the hydrofluoric acid aqueous solution discharged from the absorption tower;

and the residual liquid tanks are respectively connected with the bottoms of the first-stage rectifying tower and the second-stage rectifying tower and are used for storing residual liquid discharged from the first-stage rectifying tower and the second-stage rectifying tower.

6. A system for continuous production of electronic grade hydrofluoric acid according to claim 5, wherein: two sections of fillers and spray absorption pipes are arranged in the absorption tower, and hydrofluoric acid is adopted for absorption at the lower section; the upper section adopts ultrapure water for secondary absorption.

7. A system for continuous production of electronic grade hydrofluoric acid according to claim 5, wherein: the circulating cooling device comprises a circulating pump connected with the bottom of the absorption tower and a cooler connected with an outlet of the circulating pump.

8. A system for continuous production of electronic grade hydrofluoric acid according to claim 5, wherein: the filtering device comprises a primary filter and a secondary filter.

Technical Field

The invention belongs to the technical field of electronic chemical preparation, and particularly relates to a method and a system for preparing electronic-grade hydrofluoric acid by a continuous method.

Background

Electronic grade hydrofluoric acid is one of the fine chemicals of fluorine, mainly used for removing oxides, and one of the most used electronic chemicals in semiconductor fabrication. The electronic grade hydrofluoric acid upstream raw material is fluorite, and hydrofluoric acid is formed after a series of processing.

In recent years, with the rapid growth of the semiconductor industry in China, the demand for electronic-grade hydrofluoric acid is increased, which drives the rapid development of the electronic-grade hydrofluoric acid industry. Because the metal ion impurities in the semiconductor can affect the parameters of the lifetime, the surface conductivity, the integrity and the stability of the gate oxide and the like of minority carriers in the semiconductor, and the metal ion impurities can diffuse towards the semiconductor body or expand and distribute on the surface at high temperature or under an electric field, the performance of the semiconductor is reduced, so that the semiconductor-grade hydrofluoric acid has very strict requirements on the content of the metal ions in the semiconductor, and the larger the radius of the used wafer is, the more advanced the process is, and the higher the requirements on the content of the metal ions are.

From the global view, the production technology of electronic grade hydrofluoric acid is mainly mastered in Japanese enterprises, and the electronic grade hydrofluoric acid in China is mainly at the middle and low end. At present, the commonly used purification technologies for preparing electronic grade hydrofluoric acid in China comprise technologies such as rectification, distillation, sub-boiling distillation, reduced pressure distillation, gas absorption and the like, and the purification technologies are respectively long. Most of the purification technologies are batch production, which not only has low production efficiency and large operation intensity of workers, but also has unstable technological parameters, is easy to influence the purity grade of products, and can not produce G4-grade (UPSS-grade) hydrofluoric acid.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a simple and reliable continuous process for preparing electronic grade hydrofluoric acid, which can effectively remove metal ions and impurities in hydrogen fluoride to obtain G4 grade (UPSS grade) hydrofluoric acid in accordance with international standard SEMI-2.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

the continuous process of preparing electronic grade hydrofluoric acid includes the following steps:

(1) primary rectification: introducing the dearsenified hydrogen fluoride liquid into a primary rectifying tower, heating and gasifying the dearsenified hydrogen fluoride liquid through a primary reboiler, carrying out gas-liquid phase heat transfer, mass transfer and separation on the gasified hydrogen fluoride on the surface of a filler in the primary rectifying tower, enriching heavy component impurities such as various metal ions, non-metal ions and the like at the bottom of the tower by utilizing different boiling points of various substances in the hydrogen fluoride, and discharging the heavy component impurities into a raffinate tank; the hydrogen fluoride gas after the first-stage purification is condensed into liquid in a first-stage condenser, and the non-condensable gas is discharged into a tail gas treatment system;

(2) secondary rectification: the hydrogen fluoride liquid after the primary rectification enters a secondary rectification tower, is heated and gasified by a secondary reboiler, the gasified hydrogen fluoride is subjected to gas-liquid phase heat transfer, mass transfer and separation on the surface of a filler in the secondary rectification tower 4, and various ionic impurities which are not removed in the primary rectification are enriched at the bottom of the tower and are discharged into a residue liquid tank; the hydrogen fluoride gas purified again enters a secondary condenser, part of the hydrogen fluoride gas is condensed and flows back to a secondary rectifying tower in the secondary condenser, and the rest hydrogen fluoride gas enters an absorption tower;

(3) absorption: the hydrogen fluoride gas after the secondary rectification enters an absorption tower from the lower part and is absorbed by electronic-grade ultrapure water, absorption liquid is conveyed to the middle part of the absorption tower through a circulating pump and is sprayed downwards by a distributor for absorption, and the top of the tower is absorbed again by the electronic-grade ultrapure water; the hydrogen fluoride gas rises to the top of the tower, the gas phase and the liquid phase are subjected to countercurrent dissolution absorption on the surface of the filler, the absorption dissolution heat is carried out from the liquid phase, enters the bottom of the absorption tower, is conveyed to a cooler through a circulating pump for cooling, enters the tower from the middle of the tower again for spray absorption, and the steps are repeated in a circulating manner;

(4) and (3) filtering: and filtering the hydrofluoric acid aqueous solution discharged from the absorption tower to obtain the qualified UPSS-grade hydrofluoric acid aqueous solution.

Preferably, an on-line acid concentration meter is arranged on the circulating pipe of the absorption liquid, so that the amount of the ultrapure water added into the absorption tower can be automatically adjusted according to the concentration of the hydrofluoric acid tested by the acid concentration meter, and the concentration of the hydrofluoric acid is maintained within a set range.

Preferably, in step (3), the resistance value of the electronic grade ultrapure water is not less than 18.2 M.OMEGA.cm.

Due to the adoption of the technical scheme, the invention has at least the following beneficial effects:

(1) the invention adopts a continuous production mode, raw material hydrogen fluoride liquid is uninterruptedly input into the first-stage rectifying tower, ultrapure water is uninterruptedly input into the absorption tower, and electronic-grade hydrofluoric acid is uninterruptedly output from the device. Compared with batch production, the continuous production method has the advantages of stable technological parameters, high production efficiency and low operation intensity of workers.

(2) The gas-phase hydrogen fluoride is extracted from the top of the secondary rectifying tower, only partial condensation reflux is needed, the hydrogen fluoride is not required to be completely condensed into liquid, a large amount of refrigerant can be saved, and the energy consumption is low.

(3) The concentration of absorption liquid (electronic-grade hydrofluoric acid) in the absorption tower is always maintained in a specified concentration range, the concentration is detected on line by an acid concentration meter, and the pure water adding amount of the absorption tower is controlled by a pure water parallel lock adjusting valve, so that the concentration of the hydrofluoric acid is constant, and the quality fluctuation is avoided.

(4) After industrial-grade anhydrous hydrogen fluoride is subjected to dearsenization (Chinese patents CN101003361, CN101125639 and CN101597032A can be referred to in the dearsenization method), heavy component impurities and light component gas phase impurities in raw materials are mainly removed through primary rectification purification, the hydrogen fluoride is condensed into liquid at the tower top and then enters a secondary rectification tower, and clean metal ions and impurities which cannot be removed in the front-stage rectification are further removed; after the two-stage (or multi-stage) rectification treatment, various impurities can be removed to a high purity level, the quality of an electronic grade hydrofluoric acid product can be effectively ensured to reach a UPSS level, and the content of various cations is less than 100 ppt. A small amount of residual liquid discharged from the bottom of the rectifying tower flows into a residual liquid tank, and water can be added to blend into an industrial hydrofluoric acid product, so that resource waste is avoided.

The invention also provides a system for implementing the preparation method, which comprises the following steps:

the primary rectifying tower is used for primary rectification of the raw material hydrogen fluoride liquid;

the primary reboiler is connected with the bottom of the primary rectifying tower and is used for heating and gasifying the raw material hydrogen fluoride liquid;

the primary condenser is connected with the top of the primary rectifying tower and is used for condensing the hydrogen fluoride gas purified and purified by the primary rectifying tower;

the second-stage rectifying tower is connected with the bottom of the first-stage condenser and is used for rectifying the hydrogen fluoride liquid subjected to the first-stage rectification again;

the second-stage reboiler is connected with the bottom of the second-stage rectifying tower and is used for heating and gasifying the hydrogen fluoride liquid after the first-stage rectification;

the secondary condenser is connected with the top of the secondary rectifying tower and is used for condensing part of the hydrogen fluoride gas purified and purified again by the secondary rectifying tower, and the condensed hydrogen fluoride gas reflows into the secondary rectifying tower;

the absorption tower is connected with the bottom of the secondary condenser and is used for absorbing the hydrogen fluoride gas after secondary rectification;

the circulating cooling device is connected with the absorption tower and is used for circulating cooling of absorption liquid in the absorption tower;

a filtering device for filtering the hydrofluoric acid aqueous solution discharged from the absorption tower;

and the residual liquid tanks are respectively connected with the bottoms of the first-stage rectifying tower and the second-stage rectifying tower and are used for storing residual liquid discharged from the first-stage rectifying tower and the second-stage rectifying tower.

Preferably, two sections of fillers and spray absorption pipes are arranged in the absorption tower, and hydrofluoric acid is adopted for absorption at the lower section, so that most of hydrogen fluoride can be dissolved and absorbed; the upper segment adopts ultrapure water to carry out secondary absorption, can be furthest absorb hydrogen fluoride completely, and hydrogen fluoride content is extremely low in the tail gas, improves the utilization ratio of hydrogen fluoride.

Preferably, the circulation cooling device comprises a circulation pump connected to the bottom of the absorption tower, and a cooler connected to an outlet of the circulation pump.

Preferably, the filtration device comprises a primary filter and a secondary filter.

Drawings

The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein:

FIG. 1 is a process flow diagram of an embodiment of the invention.

In the figure: 1. a primary rectifying tower; 2. a first stage reboiler; 3. a first-stage condenser; 4. a secondary rectification column; 5. a secondary reboiler; 6. a secondary condenser; 7. an absorption tower; 8. a cooler; 9. a circulation pump; 10. a first stage filter; 11. a secondary filter; 12. an online acid concentration meter; 13. and a residual liquid tank.

Detailed Description

The invention is further illustrated below with reference to the figures and examples. In the following detailed description, certain exemplary embodiments of the present invention are described by way of illustration only. Needless to say, a person skilled in the art realizes that the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims.

Referring to fig. 1, a system for preparing electronic grade hydrofluoric acid by a continuous method is illustrated, and comprises a first-stage rectifying tower 1, a first-stage reboiler 2, a first-stage condenser 3, a second-stage rectifying tower 4, a second-stage reboiler 5, a second-stage condenser 6, an absorption tower 7, a cooler 8, a circulating pump 9, a first-stage filter 10, a second-stage filter 11, an online acid concentration instrument 12 and a residual liquid tank 13.

Two sections of fillers and spray absorption tubes are arranged in the absorption tower 7, and hydrofluoric acid is adopted for absorption at the lower section, so that most of hydrogen fluoride can be dissolved and absorbed; the upper section adopts the electronic grade ultrapure water with the resistance value of more than or equal to 18.2M omega cm for secondary absorption, so that the hydrogen fluoride can be completely absorbed to the maximum extent, the content of the hydrogen fluoride in the tail gas is extremely low, and the utilization rate of the hydrogen fluoride is improved.

Wherein, the first-stage reboiler and the second-stage reboiler are made of carbon steel, silicon carbide or fluoroplastic materials. The first-stage rectifying tower and the second-stage rectifying tower are made of steel lined with fluoroplastics, and the internal packing is Bohr ring, Raschig ring or other forms and is made of fluoroplastics. The absorption tower is made of steel lined with fluoroplastic, and the internal packing is pall ring, Raschig ring or other forms and is made of fluoroplastic. The condenser comprises a first-stage condenser, a second-stage condenser and a cooler, wherein the heat exchange tube is made of PTFE, PFA and other fluoroplastics.