System for preparing electronic-grade hydrochloric acid for semiconductor by using falling film absorber

Abstract

The utility model belongs to the field of semiconductors, and particularly relates to a system for preparing electronic-grade hydrochloric acid for semiconductors by using a falling film absorber, which comprises a dechlorination device, a dehydration adsorption tank, the falling film absorber and an alkaline washing tower, a top hydrogen chloride discharge port of the dechlorination device is connected with a bottom feed port of the dehydration adsorption tank, a top discharge port of the dehydration adsorption tank is connected to a top gas inlet of the falling film absorber, the top of the falling film absorber is also provided with a liquid inlet, and a bottom discharge port of the falling film absorber is connected to a feed port of the hydrochloric acid collection tank. According to the system, hydrogen chloride gas is purified, dehydrated and precisely filtered, then the falling film absorber made of a high-purity PFA material is used for absorbing the hydrogen chloride gas, hydrochloric acid with the concentration of 37% is prepared through one-time absorption, an absorbent is ultrapure water, the risk of metal ion dissolution is reduced, and after roughness treatment is carried out on the inner surface of a high-purity PFA membrane tube, the concentration of the high-purity PFA membrane tube is reduced. A uniform water film can be formed, and the absorption effect is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of semiconductors, and in particular relates to a system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber. Background Art

[0002] Electronic-grade hydrochloric acid is primarily used in the semiconductor field, mainly for cleaning, etching, and surface treatment. Specific applications include high-temperature vapor phase etching of silicon and gallium arsenide, and wet cleaning to remove contaminants and residual impurities from the surface of semiconductor devices.

[0003] With the increasing number of semiconductor manufacturers, the demand for electronic-grade hydrochloric acid is also growing, especially for 37% concentration electronic-grade hydrochloric acid, which is characterized by high concentration, high purity, and low metal ion content. Current purification processes mainly include distillation and sub-boiling distillation. These methods use industrial hydrochloric acid as raw material, obtaining hydrogen chloride vapor through distillation, which is then absorbed to obtain electronic-grade hydrochloric acid. Typically, the absorption towers are made of PVDF or PTFE, and the circulating absorption method significantly increases the risk of metal ion leaching, making the final electronic-grade hydrochloric acid unable to meet the requirements of the semiconductor industry. Utility Model Content

[0004] In view of the problems and shortcomings of the existing technology, the purpose of this utility model is to provide a system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a semiconductor electronic-grade hydrochloric acid preparation system, including a dechlorination device, a dehydration adsorption tank, a falling film absorber, and an alkaline washing tower; the top hydrogen chloride outlet of the dechlorination device is connected to the bottom inlet of the dehydration adsorption tank, the top outlet of the dehydration adsorption tank is connected to the top gas inlet of the falling film absorber, the top of the falling film absorber is also provided with a liquid inlet, and the bottom outlet of the falling film absorber is connected to the inlet of the hydrochloric acid collection tank.

[0007] Furthermore, the exhaust gas outlet at the top of the hydrochloric acid collection tank is connected to an alkaline scrubbing tower.

[0008] Furthermore, a two-stage precision filter is installed between the dehydration adsorption tank and the falling film absorber.

[0009] Furthermore, the chlorine outlet at the top of the dechlorination unit is connected to the feed inlet at the bottom of the alkali washing tower via a compressor.

[0010] Furthermore, the dechlorination device includes two dechlorination adsorption tanks connected in parallel.

[0011] Furthermore, the feed pipe of the dechlorination device, the hydrogen chloride discharge pipe connected to the dechlorination device, and the chlorine discharge pipe are all equipped with reversing valves.

[0012] Furthermore, the bottom outlet of the alkaline washing tower is connected to the inlet of the pump, and part of the pipeline connected to the outlet of the pump is connected to the upper inlet of the alkaline washing tower and part is connected to the waste liquid collection device; the top outlet of the alkaline washing tower is connected to the outside of the system.

[0013] Furthermore, the falling film absorber is internally arranged with membrane tubes, and the membrane tubes are provided with V-shaped grooves; the inner diameter of the membrane tubes is 12mm.

[0014] Furthermore, the membrane tube is a PFA membrane tube with a rough inner wall.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) This system purifies, dehydrates and precisely filters hydrogen chloride gas, and then uses a falling film absorber made of high-purity PFA material to absorb hydrogen chloride gas. It produces 37% hydrochloric acid in one absorption, and the absorbent is ultrapure water, which reduces the risk of metal ion dissolution. The electronic grade hydrochloric acid prepared by this system meets the requirements of the semiconductor industry.

[0017] (2) In addition, by roughening the inner surface of the high-purity PFA membrane tube, a uniform water film can be formed, which enhances the absorption effect. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the semiconductor electronic-grade hydrochloric acid preparation system of this utility model;

[0019] Figure 2 This is a schematic diagram of the falling film absorber of this utility model.

[0020] In the diagram: 1, 2 - Dechlorination adsorption tank; 3 - Dehydration adsorption tank; 4 - Falling film absorber; 5 - Hydrochloric acid collection tank; 6 - Alkali washing tower; 7 - Compressor; 8 - Primary precision filter; 9 - Secondary precision filter; 41 - Membrane tube; N1 - Liquid outlet; N2 - Gas outlet; N3 - Low-temperature chilled water inlet; N4 - Low-temperature chilled water outlet; N5 - Liquid inlet; N6 - Gas inlet; N8 - Make-up water inlet; D1 - Drain outlet; V1 - Vent outlet. DETAILED DESCRIPTION

[0021] The present invention will now be described in detail, and the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0022] Example 1

[0023] A system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber, such as Figure 1 As shown, the system includes a dechlorination unit, a dehydration adsorption tank 3, a falling film absorber 4, and an alkaline scrubbing tower 6. The top hydrogen chloride outlet of the dechlorination unit is connected to the bottom inlet of the dehydration adsorption tank 3. The top outlet of the dehydration adsorption tank 3 is connected to the top gas inlet of the falling film absorber 4. The falling film absorber 4 also has a liquid inlet at its top, and the bottom outlet of the falling film absorber 4 is connected to the inlet of the hydrochloric acid collection tank 5. The waste gas outlet at the top of the hydrochloric acid collection tank 5 is connected to the alkaline scrubbing tower 6. The chlorine outlet at the top of the dechlorination unit is connected to the bottom inlet of the alkaline scrubbing tower 6 via a compressor 7. The bottom outlet of the alkaline scrubbing tower 6 is connected to the inlet of a pump. Part of the pipeline connected to the pump outlet is connected to the top inlet of the alkaline scrubbing tower 6, and part is connected to a waste liquid collection device. The top outlet of the alkaline scrubbing tower 6 is connected to the outside of the system.

[0024] The dechlorination device includes two dechlorination adsorption tanks 1 and 2 connected in parallel; a two-stage precision filter is provided between the dehydration adsorption tank 3 and the falling film absorber 4; the two-stage precision filter includes a primary precision filter 8 and a secondary precision filter 9; membrane tubes 41 are arranged inside the falling film absorber 4, and V-shaped grooves are provided on the membrane tubes 41; the inner diameter of the membrane tubes 41 is 12mm; the membrane tubes 41 are PFA membrane tubes with a rough inner wall. Reversing valves are installed on the feed pipe of the dechlorination device, the hydrogen chloride discharge pipe connected to the dechlorination device, and the chlorine discharge pipe.

[0025] The schematic diagram of the falling film absorber of this utility model is shown below. Figure 2 As shown, the falling film absorber 4 includes a membrane tube 41; a liquid outlet N1; a gas outlet N2; a low-temperature chilled water inlet N3; a low-temperature chilled water outlet N4; a liquid inlet N5; a gas inlet N6; a water replenishment port N8; a drain port D1; and a vent port V1.

[0026] During production, hydrogen chloride gas from the synthesis furnace is dechlorinated to less than 10 ppm in dechlorination adsorption tank 1. After adsorption for a certain period, it is switched to dechlorination adsorption tank 2. Dechlorination adsorption tank 1 is regenerated under reduced pressure, and the cycle is repeated. The dechlorinated hydrogen chloride gas continues to enter dehydration adsorption tank 3, where it is also dehydrated to below 10 ppm. Then, it flows through two stages of precision filtration (50 nm and 20 nm) before entering the high-purity PFA falling film absorber 4. Hydrogen chloride gas and ultrapure water flow in parallel from the top into the membrane tube 41, forming a gas film and a liquid film two-phase system. At the phase interface... Mass transfer occurs between the gas film and liquid film due to the concentration gradient. The concentration of hydrogen chloride in the liquid film gradually increases as the liquid film flows downward. Due to the phase change that occurs during the dissolution process, a large amount of heat is released. The cooling water in the shell side of the falling film absorber 4 removes the heat in time to maintain the temperature of the liquid film in the tube side. After absorption, the liquid film flows into the hydrochloric acid collection tank 5. The concentration of hydrochloric acid is adjusted by controlling the flow rate of ultrapure water. Finally, the ratio of ultrapure water to hydrogen chloride is adjusted to obtain 37% hydrochloric acid. The small amount of unabsorbed hydrogen chloride gas enters the alkaline scrubbing tower 6, is absorbed by the alkaline solution, and is then discharged into the atmosphere.

[0027] Hydrogen chloride gas, after purification, dehydration, and precision filtration, enters from the gas inlet N6 at the top of the falling film absorber 4. Ultrapure water enters from the liquid inlet N5 at the top of the falling film absorber 4. After the ultrapure water reaches a certain level, it overflows into the inner wall of the membrane tube 41 through the V-shaped groove. Due to the roughness pretreatment of the inner wall surface of the high-purity PFA membrane tube, a water film with a thickness of 2-3 mm will form on the surface of the high-purity PFA membrane tube. The inner diameter of the high-purity PFA membrane tube 41 is 12 mm. Hydrogen chloride gas passes through the center of the membrane tube 41. After sufficient gas-liquid mass transfer, more than 99% of the hydrogen chloride gas is absorbed by the ultrapure water, and 1% of the hydrogen chloride gas is discharged from the gas phase outlet at the bottom of the falling film absorber 4. The concentration of the ultrapure water after absorbing hydrogen chloride gas increases stepwise from top to bottom along the membrane tube 41 to 37%. Finally, it enters the hydrochloric acid collection tank 5 to prepare 37% electronic-grade hydrochloric acid that meets the requirements for semiconductor use.

[0028] Although the description of this utility model has been given in conjunction with the specific embodiments described above, it is obvious to those skilled in the art that many substitutions, modifications, and variations can be made based on the above description. Therefore, all such substitutions, modifications, and variations should fall within the protection scope of the claims of this utility model.

Claims

1. A system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber, characterized in that, It includes a dechlorination device, a dehydration adsorption tank, a falling film absorber, and an alkaline washing tower; the top hydrogen chloride outlet of the dechlorination device is connected to the bottom inlet of the dehydration adsorption tank, the top outlet of the dehydration adsorption tank is connected to the top gas inlet of the falling film absorber, the top of the falling film absorber is also provided with a liquid inlet, and the bottom outlet of the falling film absorber is connected to the inlet of the hydrochloric acid collection tank.

2. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 1, characterized in that, The exhaust gas outlet at the top of the hydrochloric acid collection tank is connected to the alkaline scrubbing tower.

3. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 1, characterized in that, Two-stage precision filters are installed between the dehydration adsorption tank and the falling film absorber.

4. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 2, characterized in that, The chlorine outlet at the top of the dechlorination unit is connected to the feed inlet at the bottom of the alkali washing tower via a compressor.

5. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 3, characterized in that, The dechlorination device includes two dechlorination adsorption tanks connected in parallel.

6. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 4, characterized in that, The feed pipe of the dechlorination device, the hydrogen chloride discharge pipe connected to the dechlorination device, and the chlorine discharge pipe are all equipped with reversing valves.

7. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 2, characterized in that, The bottom outlet of the alkaline washing tower is connected to the inlet of the pump, and part of the pipeline connected to the outlet of the pump is connected to the upper inlet of the alkaline washing tower and part is connected to the waste liquid collection device; the top outlet of the alkaline washing tower is connected to the outside of the system.

8. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 1, characterized in that, The falling film absorber has membrane tubes arranged inside, and the membrane tubes are provided with V-shaped grooves; the inner diameter of the membrane tubes is 12mm.

9. The system for preparing electronic-grade hydrochloric acid for semiconductors using a falling film absorber according to claim 8, characterized in that, The membrane tube is a PFA membrane tube with a rough inner wall.

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