Preparation process of electronic-grade hydrofluoric acid

Abstract

The invention relates to a preparation process of electronic-grade hydrofluoric acid, and belongs to the technical field of hydrofluoric acid preparation, and the method comprises the following steps: introducing anhydrous hydrofluoric acid into a precision filtering system for preliminarily filtering particulate matters, conveying the filtered anhydrous hydrofluoric acid to a reboiler, heating and gasifying to form gaseous hydrofluoric acid, conveying the gaseous hydrofluoric acid to a multi-stage condenser for stage-by-stage cooling, injecting an oxidizing agent, mixing with the liquid anhydrous hydrofluoric acid, heating and gasifying in a reboiler to form gaseous hydrofluoric acid, conveying the gaseous hydrofluoric acid to a particle filter to remove microparticles so as to form pure gaseous hydrofluoric acid, conveying the pure gaseous hydrofluoric acid to a mixing and cooling device, mixing with low-temperature ultrapure water, and cooling, forming electronic grade hydrofluoric acid; the device has the advantages that impurities with boiling points close to that of hydrofluoric acid can be conveniently removed, and the purity can be conveniently improved.

Description

Technical Field

[0001] The invention relates to a preparation process of electronic-grade hydrofluoric acid, and belongs to the field of hydrofluoric acid preparation. Background Art

[0002] Electronic-grade hydrofluoric acid is a high-purity chemical reagent, mainly used in the manufacturing process of the microelectronics industry, such as large-scale integrated circuits, thin-film liquid crystal displays, semiconductors, etc. Its purity and cleanliness have a very important impact on the yield, electrical properties and reliability of integrated circuits. In the semiconductor manufacturing process, electronic-grade hydrofluoric acid is mainly used for wafer surface cleaning, cleaning and corrosion in the chip processing process, etc.

[0003] In the traditional preparation process of electronic-grade hydrofluoric acid, filtration, gasification, condensation and other methods are usually used to remove particulate matter and impurities in anhydrous hydrofluoric acid. However, these traditional methods often have certain shortcomings, such as low filtration efficiency, easy to cause filter clogging, incomplete discharge of high-boiling point impurities and low-boiling point impurities during the treatment process, and it is difficult to meet the strict requirements of the electronics industry for high-purity hydrofluoric acid. In addition, the traditional process also has problems in continuity and stability, and frequent shutdowns for cleaning increase production costs. Summary of the invention

[0004] The present invention aims at the defects existing in the above prior art and provides a preparation process of electronic grade hydrofluoric acid, which solves the problem of improving the filtering efficiency of impurities.

[0005] The object of the present invention is achieved by the following technical scheme: a process for preparing electronic grade hydrofluoric acid, comprising the following steps: First stage filtration, vaporization, condensation and purification process: Anhydrous hydrofluoric acid enters the precision filtration system to initially filter out particulate matter; The filtered anhydrous hydrofluoric acid is transported to a first reboiler, heated with pure water at 22° C., gasified, and high-boiling-point impurities are discharged to an impurity collection tank to form a first gaseous hydrofluoric acid; The first gaseous hydrofluoric acid is conveyed to a multi-stage condenser, and is cooled step by step using pure water of different temperatures to condense the first gaseous hydrofluoric acid to form a first liquid anhydrous hydrofluoric acid, and the first liquid anhydrous hydrofluoric acid is conveyed to a buffer storage tank filled with an inert gas for temporary storage, and low-boiling impurities are discharged to an exhaust gas treatment device; Second stage gasification, filtration, mixing and cooling: injecting an oxidant and mixing with the first liquid anhydrous hydrofluoric acid; The liquid anhydrous hydrofluoric acid mixed with the oxidant is heated and vaporized by using pure water at 22° C. in a second reboiler, and high boiling point impurities are discharged to an impurity collection tank to form a second gaseous hydrofluoric acid; delivering the second gaseous hydrofluoric acid to a particle filter to remove microparticles to form pure gaseous hydrofluoric acid; The pure gaseous hydrofluoric acid is transported to the mixing and cooling equipment, mixed with low-temperature ultrapure water, and cooled to form electronic grade hydrofluoric acid.

[0006] In the above-mentioned method for preparing electronic-grade hydrofluoric acid, further, the precision filtration system includes a pre-filter, a precision filter, a backwashing system and a flow control system. Before gasification, a layer of precision filtration device is added to remove tiny particles and preliminary high-boiling point impurities to reduce the burden of subsequent processing. When the filter is clogged to a certain extent, impurities on the filter element are removed by backwashing to restore its filtration performance. It is equipped with precise pressure and flow control devices to maintain suitable filtration conditions.

[0007] In the above-mentioned method for preparing electronic-grade hydrofluoric acid, further, the pre-filter adopts a coarse-pore filter screen or filter element with a pore size between 75μm and 150μm, which is used to remove large particles of impurities, such as dust, sand, etc., to protect subsequent precision filtration elements from damage.

[0008] In the above-mentioned method for preparing electronic-grade hydrofluoric acid, further, the precision filter adopts a filter element or membrane material with a fine pore size, and the pore size is between 0.1μm and 10μm. This is the core component of the system, which can effectively intercept micron-level or even nano-level tiny particles and soluble impurities. According to specific needs, it can be designed as single-stage or multi-stage filtration to gradually improve the filtration accuracy.

[0009] In the above-mentioned method for preparing electronic-grade hydrofluoric acid, further, the temperature range in the multi-stage condenser is 16~22°C, the temperature of pure water used for condensation in the lowest layer is 16°C, and the temperature is lowered step by step to more effectively separate and discharge gas impurities with a liquefaction temperature different from that of hydrofluoric acid, thereby improving the purity of hydrofluoric acid.

[0010] In the above-mentioned method for preparing electronic-grade hydrofluoric acid, further, each layer of the multi-stage condenser is connected to an impurity collection tank to facilitate the discharge of the impurities that have been liquefied in advance.

[0011] In the above-mentioned method for preparing electronic-grade hydrofluoric acid, further, the oxidant is selected from potassium permanganate, ammonium persulfate, potassium bifluoride or fluorine gas, and the oxidant is mixed with liquid anhydrous hydrofluoric acid to oxidize trivalent arsenic to pentavalent arsenic.

[0012] In summary, compared with the prior art, the present invention has the following advantages: 1. In the scheme of the present invention, the particulate matter and impurities in the anhydrous hydrofluoric acid are effectively removed through fine filtration, gasification, condensation and purification treatment, ensuring the high purity and excellent quality of the final product, and meeting the stringent requirements of the electronics industry for high-purity hydrofluoric acid; 2. In the scheme of the present invention, the multi-stage condenser is used for step-by-step cooling, and the pre-filtration and precision filtration systems are added to reduce the probability of filter blockage and the frequency of shutdown for cleaning, thereby improving production continuity and stability; 3. In the scheme of the present invention, the pre-filter and the precision filter are reasonably designed. The pre-filter can effectively remove large particle impurities and protect the subsequent precision filter element, while the precision filter can intercept micron-level or even nano-level tiny particles and soluble impurities, thereby reducing the burden of subsequent processing and avoiding the impact of impurities on the quality of the final product; 4. In the scheme of the present invention, the temperature range setting in the multi-stage condenser enables gas impurities to be separated and discharged more effectively, further improving the purity of hydrofluoric acid and reducing the corrosion of the equipment caused by impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A route flow diagram was prepared for the present invention. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further specifically described below through specific embodiments, but the present invention is not limited to these embodiments.

[0015] Embodiment 1 The first stage: filtration, vaporization, condensation and purification 1.1 Filtering First, anhydrous hydrofluoric acid enters the precision filtration system through the feed pipe. The precision filtration system includes a pre-filter, a precision filter, a backwash system and a flow control system. Anhydrous hydrofluoric acid first passes through the pre-filter, which uses a coarse-pore filter or filter element with a pore size of 75μm to 150μm to remove large particles of impurities such as dust and sand to protect subsequent precision filtration elements from damage.

[0016] Subsequently, anhydrous hydrofluoric acid enters the precision filter, which uses a fine-pore filter element or membrane material with a pore size of 0.1μm to 10μm to effectively intercept micron-level or even nano-level tiny particles and soluble impurities. During the filtration process, if the filter is blocked to a certain extent, it is backwashed through the backwashing system to remove impurities on the filter element and restore its filtration performance. The flow control system ensures that the pressure and flow maintain appropriate conditions during the filtration process.

[0017] 1.2 Gasification The filtered anhydrous hydrofluoric acid is transported to the first reboiler and heated with pure water at 22° C. to gasify the anhydrous hydrofluoric acid. In this process, high boiling point impurities are discharged to the impurity collection tank to form the first gaseous hydrofluoric acid.

[0018] 1.3 Condensation The first gaseous hydrofluoric acid is transported to a multi-stage condenser and cooled step by step using pure water of different temperatures. The temperature range in the multi-stage condenser is 16~22℃, and the temperature of the pure water used for condensation in the bottom layer is 16℃. The temperature is lowered step by step to more effectively separate and discharge gas impurities with different liquefaction temperatures from hydrofluoric acid. The condensed first liquid anhydrous hydrofluoric acid is transported to a buffer storage tank filled with inert gas for temporary storage, while the low-boiling impurities are discharged to the tail gas treatment device.

[0019] Second stage: gasification, filtration, mixing and cooling 2.1 Gasification and Filtration The oxidant (such as potassium permanganate, ammonium persulfate, potassium bifluoride or fluorine gas) is injected into the first liquid anhydrous hydrofluoric acid and mixed evenly. The mixed liquid anhydrous hydrofluoric acid is transported to the second reboiler and heated and vaporized using 22°C pure water. In this process, high boiling point impurities are discharged into the impurity collection tank to form the second gaseous hydrofluoric acid.

[0020] The second gaseous hydrofluoric acid is delivered to a particle filter to remove fine particles to form pure gaseous hydrofluoric acid.

[0021] 2.2 Mixing and cooling The pure gaseous hydrofluoric acid is transported to the mixing and cooling equipment, mixed with low-temperature ultrapure water, and cooled to form electronic grade hydrofluoric acid. The final product is output through the discharge pipeline.

[0022] From the above examples, it can be seen that the electronic grade hydrofluoric acid preparation process provided by the present invention effectively improves the purity of hydrofluoric acid through multi-stage treatment, and meets the demand of the electronics industry for high-purity hydrofluoric acid.

[0023] Embodiment 2 Compared with Example 1, the preparation process of Example 2 is basically the same, but a layer of precision filtration device is added to the precision filtration system to further remove tiny particles and preliminary high-boiling impurities, reducing the burden of subsequent processing. The precision filtration device can be designed as single-stage or multi-stage filtration according to actual needs to gradually improve the filtration accuracy, and the rest is the same as Example 1.

[0024] The implementation of the present invention is not limited to the above-mentioned embodiments. Without departing from the spirit and scope of the present invention, ordinary technicians in this field can make various changes and improvements to the present invention in form and detail, and these are considered to fall within the protection scope of the present invention.

Claims

1. A process for preparing electronic grade hydrofluoric acid, characterized in that: The steps include: First stage filtration, vaporization, condensation and purification process: Anhydrous hydrofluoric acid enters the precision filtration system to initially filter out particulate matter; The filtered anhydrous hydrofluoric acid is transported to a first reboiler, heated with pure water at 22° C., gasified, and high-boiling-point impurities are discharged to an impurity collection tank to form a first gaseous hydrofluoric acid; The first gaseous hydrofluoric acid is conveyed to a multi-stage condenser, and is cooled step by step using pure water of different temperatures to condense the first gaseous hydrofluoric acid to form a first liquid anhydrous hydrofluoric acid, and the first liquid anhydrous hydrofluoric acid is conveyed to a buffer storage tank filled with an inert gas for temporary storage, and low-boiling impurities are discharged to an exhaust gas treatment device; Second stage gasification, filtration, mixing and cooling: injecting an oxidant and mixing with the first liquid anhydrous hydrofluoric acid; The liquid anhydrous hydrofluoric acid mixed with the oxidant is heated and vaporized by using pure water at 22° C. in a second reboiler, and high boiling point impurities are discharged to an impurity collection tank to form a second gaseous hydrofluoric acid; delivering the second gaseous hydrofluoric acid to a particle filter to remove microparticles to form pure gaseous hydrofluoric acid; The pure gaseous hydrofluoric acid is transported to the mixing and cooling equipment, mixed with low-temperature ultrapure water, and cooled to form electronic grade hydrofluoric acid.

2. A process for preparing electronic grade hydrofluoric acid according to claim 1, characterized in that: The precision filtration system includes a pre-filter, a precision filter, a backwashing system and a flow control system.

3. A process for preparing electronic grade hydrofluoric acid according to claim 2, characterized in that: The pre-filter adopts a filter screen or filter element with a coarse pore size, and the pore size is between 75 μm and 150 μm.

4. A process for preparing electronic grade hydrofluoric acid according to claim 3, characterized in that: The precision filter adopts a filter element or membrane material with a fine pore size, and the pore size is between 0.1 μm and 10 μm.

5. A process for preparing electronic grade hydrofluoric acid according to claim 1, characterized in that: The temperature range in the multi-stage condenser is 16-22°C, and the temperature of pure water used for condensation in the bottom layer is 16°C.

6. A process for preparing electronic grade hydrofluoric acid according to claim 5, characterized in that: Each layer of the multi-stage condenser is connected to an impurity collecting tank.

7. A process for preparing electronic grade hydrofluoric acid according to claim 1, characterized in that: The oxidant is selected from potassium permanganate, ammonium persulfate, potassium hydrogen fluoride or fluorine gas.

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