CN101570318A - Method for producing electronic-grade hydrofluoric acid - Google Patents

Abstract

The invention relates to a method for producing electronic-grade hydrofluoric acid, which specifically comprises the following steps: (1) preheating the metered anhydrous hydrofluoric acid raw material, and performing rough distillation to remove low-boiling-point substances; (2) absorbing hydrofluoric acid discharged from the outlet of the condenser after the rough distillation into 48-49% of aqueous hydrofluoric acid solution by using ultrapure water; (3) distilling the absorbed hydrofluoric acid semi-finished product by a fluoroplastic resin sub-boiling distiller, gasifying the hydrogen fluoride liquid to generate ultra-pure electronic-grade hydrofluoric acid gas, condensing to obtain 48-49% aqueous hydrofluoric acid solution, and leaving high-boiling-point substances and heavy metals at the bottom of the sub-boiling distiller; (4) and (3) carrying out secondary filtration on the hydrofluoric acid semi-finished product discharged from the fluoroplastic resin sub-boiling distiller, and finally carrying out automatic filling to prepare a 48% ultra-pure hydrofluoric acid finished product. The method of the invention makes full use of the different boiling points of the anhydrous hydrofluoric acid and the impurities in the anhydrous hydrofluoric acid to remove different impurities, especially silicon, at different temperatures, so that the impurity content of the obtained ultra-pure hydrofluoric acid is reduced to the minimum.

Description

A method of producing electronic grade hydrofluoric acid

technical field

The invention relates to a method for producing electronic-grade hydrofluoric acid, in particular to a method for producing electronic-grade hydrofluoric acid with anhydrous hydrofluoric acid as the main raw material.

Background technique

Electronic grade hydrofluoric acid (Hydrofuloric acid, electronic grade) is also called high-purity hydrofluoric acid. Molecular formula HF, molecular weight 20.006. As one of the key basic chemical materials for the manufacture of integrated circuits (IC), electronic grade hydrofluoric acid is mainly used for chip cleaning and corrosion. very important influence. With the rapid development of electronics, information, and communication industries, the requirements for the purity and impurities of reagent hydrofluoric acid are getting higher and higher, and the demand has also increased sharply. The general electronic pure hydrofluoric acid is far from meeting the harshness of the market. The preparation of high-purity hydrofluoric acid has become one of the directions for hydrogen fluoride production enterprises to further process and increase the added value of products. Electronic grade hydrofluoric acid has the characteristics of many varieties, large dosage, high technical requirements, short shelf life and strong corrosiveness.

At present, the reaction of industrial anhydrous hydrofluoric acid and potassium permanganate is generally used, followed by direct distillation and purification to prepare electronic grade hydrofluoric acid, that is, high-purity hydrogen fluoride. The purity of hydrofluoric acid produced by this method is relatively low, especially hydrogen The separation of arsenic trifluoride in hydrofluoric acid is not complete, so the ultra-high-purity hydrofluoric acid produced by this method is difficult to apply in ultra-large-scale integrated circuits (microelectronics industry); at the same time, the process parameters in the production process are not easy to control. In addition, in the current preparation process of electronic grade hydrofluoric acid, because hydrogen fluoride gas cannot be completely absorbed, its tail gas emission is likely to cause pollution to the surrounding environment.

Contents of the invention

The object of the present invention is to provide a kind of method of producing electronic grade hydrofluoric acid, and its technological process is simple, and investment is little, and the product purity of production is high.

In order to achieve the above object, the technical solution of the present invention has adopted a kind of method for producing electronic grade hydrofluoric acid, specifically comprises the following steps:

(1) Crude distillation: After the measured anhydrous hydrofluoric acid raw material is preheated, carry out crude distillation to remove low boiling point substances;

(2) Absorption: Absorb the hydrofluoric acid discharged from the outlet of the condenser after crude distillation with ultrapure water. 20～40℃, the condensed liquid is 48～49% aqueous hydrofluoric acid solution;

(3) Rectification in fluoroplastic subboiling distiller: Distill the absorbed semi-finished product of hydrofluoric acid through a fluoroplastic subboiling distiller at a temperature of 60-80°C, and gasify hydrogen fluoride liquid to produce ultra-pure electronic grade hydrofluoric acid Acid gas, condensed into 48-49% aqueous hydrofluoric acid solution, high boiling point substances and heavy metals remain at the bottom of the sub-boiling distiller;

(4) Membrane filtration: The semi-finished product of hydrofluoric acid from the sub-boiling distiller of fluorine plastic resin is filtered through the second stage and finally made into 48% ultra-high-purity hydrofluoric acid finished product through automatic filling.

The specific steps of the step (1) are: the metered anhydrous hydrofluoric acid raw material flows out from the storage bottle, enters the crude still after being preheated by the preheater, and in the crude still, controls the When the pressure is less than 0.2Mpa, add an oxidizing agent, the amount of which accounts for 0.5-2.5% of the weight of the anhydrous hydrofluoric acid raw material, so that a large amount of sulfur dioxide and arsenic trifluoride contained in the industrial anhydrous hydrofluoric acid form a compound that is difficult to volatilize; then add Hydrogen peroxide with a weight concentration of 30%, the addition of hydrogen peroxide accounts for 1 to 3% of industrial anhydrous hydrogen fluoride, the temperature in the crude distillation tower is 30 to 50°C, and the outlet temperature of the top condenser is 10 to 19 ℃.

The oxidant is one of potassium permanganate solution, (NH4)2S2O8 or KHF2 or a combination thereof.

The filtration in the step (4) is specifically: after filtering through a first-level 0.2 μm microporous membrane in a class 100 ultra-clean room, and then entering a second-level 0.05 μm microporous membrane for filtration.

The method of the present invention makes full use of the different boiling points of the impurities in anhydrous hydrofluoric acid and anhydrous hydrofluoric acid, and removes different impurities, especially silicon, at different temperatures, so that the impurity content of the obtained ultra-high-purity hydrofluoric acid is reduced to lowest. The present invention utilizes the strong oxidizing properties of oxidant potassium permanganate, (NH4)2S2O8, KHF2 and hydrogen peroxide to oxidize a large amount of sulfur dioxide and arsenic trifluoride contained in industrial anhydrous hydrogen fluoride to generate sulfur trioxide and K2AsF7 which are difficult to volatilize , These compounds have a high boiling point, and are not easily taken out during the crude distillation process and exist at the bottom of the crude still and discharged from the system. The invention not only improves the purity of ultra-high-purity hydrofluoric acid, but also increases economic and environmental benefits.

The present invention utilizes the heat radiation principle of the fluoroplastic sub-boiling distiller to keep the liquid phase temperature lower than the boiling point temperature to evaporate and condense to produce high-purity reagents, which reduces equipment and investment, increases output, and further reduces production costs.

The inventive method has following advantage compared with current production technique:

(1) Through the different boiling points of various substances, the strong oxidizing properties of potassium permanganate or (NH4)2S2O8 and KHF2 and hydrogen peroxide, the difficult problems of silicon and trivalent arsenic that are not easy to be removed are completely solved, and fluoroplastic grease sub- Boiling distiller distillation further improves product purity, and the obtained ultra-high-purity hydrofluoric acid meets the semiconductor SEMI-C12 standard, which meets the needs of microelectronics industry technology, especially VLSI. The finished product index is: purity: anion ≤ 25ppb, cation ≤ 0.03ppb.

(2) The waste acid solution produced by the present invention generally contains hydrofluoric acid, fluosilicic acid, etc., with a concentration of about 50-60%, and can be used in cryolite production lines. The pressure of environmental protection is relieved, the consumption is reduced, and the cost is saved.

(3) The present invention performs membrane filtration twice on the semi-finished product of hydrofluoric acid, so that the particle impurity content in the ultra-high-purity hydrofluoric acid is reduced to the minimum, reaching the semi-conductor SEMI-C12 standard. The number of particles is 0.2μm≤50.

(4) The present invention utilizes the fluoroplastic grease sub-boiling still to carry out secondary rectification, which reduces equipment and investment, and the equipment is simple and occupies a small area, while increasing the output and further reducing the production cost.

Detailed ways

Example 1

The method of the present invention specifically comprises the following steps: (1) crude distillation: the anhydrous hydrofluoric acid raw material of 350kg flows out from the storage bottle, adds the crude still of band heat exchanger, in the crude still, controls the crude still If the internal pressure is less than 0.2Mpa, add 5.25kg of potassium permanganate solution to make a large amount of sulfur dioxide and arsenic trifluoride contained in industrial anhydrous hydrofluoric acid form difficult-to-volatilize compounds; Hydrogen oxide, the gas distilled out at a temperature of 30-50°C in the crude distillation still rises continuously, passes through the crude distillation tower, and then enters the water condenser directly installed on the top of the tower, and repeatedly condenses, refluxes, and vaporizes, and the gas, The two phases of the liquid are in close contact repeatedly in the water condenser and the upper part of the crude distillation tower, and the temperature of the gas derived from the top outlet of the water condenser is controlled at 15°C; (2) Absorption: the gas derived from the top outlet of the water condenser is absorbed by the spray The bottom of the tower enters the tower and is absorbed by the spray absorption liquid sprayed from the top of the tower, absorbing into a 50-60% acid solution, which is used in other processes or sold as a commodity; the gas that is exported from the top outlet of the water condenser When reaching 1.5% of anhydrous hydrofluoric acid weight, adjust condenser outlet temperature to be 35 ℃, carry out hydrofluoric acid gasification, the hydrofluoric acid after gasification is passed in the absorption tower and absorb; The acid is passed into the absorption tower and absorbed with ultra-pure water. The temperature of the tower kettle is 60°C, the temperature of the tower body is 45°C, the outlet temperature of the condenser is 30°C, and the condensed liquid absorbs 48% to 49% of hydrous hydrogen Fluoric acid solution; (3) Rectification by fluoroplastic fat sub-boiling distiller: carry out secondary rectification with 48% to 49% hydrofluoric acid solution in fluoroplastic fat sub-boiling distiller, the temperature is 70°C; (4) Membrane filtration: The semi-finished product of hydrofluoric acid distilled from the fluoroplastic sub-boiling still is filtered through a 0.2μm microporous membrane in a class 100 ultra-clean room, and then enters a secondary 0.05μm microporous membrane for filtration (particles Number is 0.3 μm≤100), after filtering, obtain the ultra-high-purity hydrofluoric acid finished product of 640kg 48% (wt). Analysis results: the number of particles is 0.2 μm ≤ 50, the purity: anion ≤ 25ppb, cation ≤ 0.03ppb.

Example 2

The method of the present invention specifically comprises the following steps: (1) crude distillation: the anhydrous hydrofluoric acid raw material of 250kg flows out from the storage bottle, adds the crude still of band heat exchanger, in the crude still, controls the crude still Internal pressure is less than 0.2Mpa, add 2.5kg (NH4) 2S2O8, make a large amount of sulfur dioxide and arsenic trifluoride contained in industrial anhydrous hydrofluoric acid generate the compound that is difficult to volatilize; Then add 5kg weight percent and be 30% peroxide Hydrogen, the gas distilled out at a temperature of 30-50°C in the crude still rises continuously, passes through the crude distillation tower, and then enters the water condenser directly installed on the top of the tower, and repeatedly condenses, refluxes, and vaporizes. The two phases are repeatedly and closely contacted in the water condenser and the upper part of the crude distillation tower, and the temperature of the gas derived from the top outlet of the water condenser is controlled at 20°C; The bottom of the tower enters the tower and is absorbed by the spray absorption liquid sprayed from the top of the tower, absorbing into a 50-60% acid solution, which is used in other processes or sold as a commodity; the gas exported from the top outlet of the water condenser reaches When the weight of anhydrous hydrofluoric acid is 2%, the outlet temperature of the condenser is adjusted to be 35°C, and the hydrofluoric acid is vaporized, and the gasified hydrofluoric acid is passed into the absorption tower for absorption; the hydrofluoric acid at the condenser outlet is It is passed into the absorption tower and absorbed with ultra-pure water. The temperature of the tower kettle is 55°C, the temperature of the tower body is 40°C, and the outlet temperature of the condenser is 40°C. The condensed liquid absorbs 48% to 49% of hydrofluoric acid in water Acid solution; (3) Rectification by fluoroplastic sub-boiling distiller: 48% to 49% hydrofluoric acid solution is subjected to secondary rectification in fluoroplastic sub-boiling distiller at a temperature of 80°C; (4) membrane Filtration: The semi-finished product of hydrofluoric acid distilled from the fluoroplastic fat sub-boiling distiller is filtered through a 0.2μm microporous membrane in a class 100 ultra-clean room, and then enters a secondary 0.05μm microporous membrane for filtration (the number of particles 0.3 μm ≤ 100), filter to get 400kg 49% (wt) ultra-high-purity hydrofluoric acid finished product. Analysis results: the number of particles is 0.2 μm ≤ 50, the purity: anion ≤ 25ppb, cation ≤ 0.03ppb.

Finally, it should be noted that: the above embodiments are only used to illustrate, rather than limit the technical solution of the present invention, although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be carried out Any modification or equivalent replacement without departing from the spirit and scope of the present invention shall fall within the scope of the claims of the present invention.

Claims (4)

1, a kind of method of producing electronic-stage hydrofluoric acid is characterized in that: specifically may further comprise the steps:

(1) slightly heat up in a steamer: the anhydrous hydrofluoric acid raw material through measuring slightly heats up in a steamer after preheating, removes low-boiling point material;

(2) absorb: will be after slightly heating up in a steamer, the hydrofluoric acid of discharging from condensator outlet absorbs with ultrapure water, and tower still temperature is 40～60 ℃, and the body of the tower temperature is 40～50 ℃, the condensator outlet temperature is 20～40 ℃, condensed liquid be 48～49% the water hydrofluoric acid solution arranged;

(3) fluorine is moulded the rectifying of fat sub-boiling distillation device: the hydrofluoric acid work in-process of good absorption are moulded the distillation of fat sub-boiling distillation device through fluorine, temperature is 60～80 ℃, the gasification of hydrogen fluoride liquid generates hyperpure electronic-stage hydrofluoric acid gas, after the condensation be 48～49% the water hydrofluoric acid solution arranged, high boiling substance and heavy metal are stayed sub-boiling distillation device bottom;

(4) membrane filtration: from fluorine mould hydrofluoric acid work in-process that fat sub-boiling distillation device comes out through cascade filtration after auto-filling is made 48% ultra-pure hydrofluoric acid finished product.

2, the method for production electronic-stage hydrofluoric acid according to claim 1, it is characterized in that: the concrete steps of described step (1) are: the anhydrous hydrofluoric acid raw material after will measuring flows out in the storage bottle, after the preheater preheating, enter and slightly heat up in a steamer still, slightly heating up in a steamer in the still, control is slightly heated up in a steamer the still internal pressure less than 0.2Mpa, add oxygenant, its add-on accounts for 0.5～2.5% of anhydrous hydrofluoric acid raw material weight, makes a large amount of sulfurous gas and the arsenous fluoride generation that contain in the anhydrous hydrogen fluoride for industrial use be difficult to the evaporable compound; Add weight concentration then and be 30% hydrogen peroxide, the add-on of hydrogen peroxide accounts for 1～3% of anhydrous hydrogen fluoride for industrial use, is 30～50 ℃ at the topping still temperature in the kettle, and the overhead condenser temperature out is 10～19 ℃.

3, the method for production electronic-stage hydrofluoric acid according to claim 2 is characterized in that: described oxygenant is a kind of or its combination among potassium permanganate solution, (NH4) 2S208 or the KHF2.

4, according to the method for arbitrary described production electronic-stage hydrofluoric acid among the claim 1-3, it is characterized in that: the filtration of described step (4) is specially: between hundred-grade super-clean behind one-level 0.2 μ m filtering with microporous membrane, enter secondary 0.05 μ m filtering with microporous membrane again.