CS258702B1 - Process of producing hydrochloric acid] for microelectronics - Google Patents

Abstract

Sulfuric acid is gradually added to aqueous solutions of hydrogen chloride and/or chlorides. The released hydrogen chloride is countercurrently stripped of water in sulfuric acid and droplets in a droplet separator. The purified hydrogen chloride is adsorbed in microelectronics-grade water onto an aqueous solution of hydrochloric acid. In the purified hydrochloric acid, metal cations, especially iron, are adsorbed with silicates with active adsorption sites. The solution can be used in the electrical industry.

Description

The invention relates to the production of hydrochloric acid for microelectronics, which is particularly suitable for planar integrated circuit technology.

The production of hydrochloric acid] is one of the oldest production of the chemical industry. Currently, the largest amount of hydrochloric acid is produced by the synthesis of hydrogen and chlorine and the absorption of the resulting hydrogen chloride in water. The development of microelectronics has increased the purity requirements of the chemicals used in their manufacture, as impurities from the chemicals cause the production of poor quality microelectronic components. Purification of the hydrochloric acid by distillation of the aqueous hydrochloric solution yields a distillate of high chemical purity followed by microfilters having a mesh size of 0.2 to 0.45 microns and filtered to the desired physical purity. here.

These findings have been drawn from the following works and materials: E. D. Stepun et al. - Metody polučenija osobo pure neorganičeskich vešěestv. Moskva 1969; Catalog of Sartórius 1984; Millipore 1983; Catalog by Ferck - Selectipur MOS 1983 and Catalog by Carlo · Erba - Montedison 1983.

Commonly prepared hydrochloric acid contains on the order of 10 ⁶ heteroparticles per liter greater than 0.5 microns, therefore microfiltration of hydrochloric acid is expensive.

Also, rectification of hydrochloric acid is an energy-intensive process.

In U.S. Patent 3,855,400 (1974) by Paolieri R. et al. describes the purification method of hydrochloric acid obtained as a secondary product from the production of organic compounds, by stripping method and by flushing with an inert gas stream, which purely removes soluble organic substances and free chlorine. The insoluble organic matter is removed by flowing the acid through the pores of the co-permissive medium, agglomerating and separating. The purity of the thus prepared and purified hydrochloric acid is of poor quality for microelectronics.

The aforementioned drawbacks are alleviated by the method of producing hydrochloric acid for microelectronics, which comprises adding successively concentrated sulfuric acid to aqueous solutions of chloride and / or hydrochloric acid. releases hydrogen chloride gas, which is dried by countercurrent flowing concentrated sulfuric acid, which is added to aqueous chloride and / or hydrogen chloride solutions. The dried hydrogen chloride is stripped of the entrained drops of sulfuric acid by a drop trap. The purified hydrogen chloride is absorbed in high purity microelectronics grade water to an aqueous hydrochloric acid solution. The material to be made is selected according to the desired degree of hydrochloric acid obtained. Impurities, especially polar substances, are adsorbed with silicates with active adsorption sites. These are mainly metal cations, especially iron.

The invention can be used for the production of hydrochloric acid for microelectronics, which is mainly used in the production of integrated circuits in the electronics industry.

Example 1

The three-necked flask was charged with 37 wt. Hydrochloric acid. The flask was equipped with a thermometer, a separatory funnel for the addition of hydrochloric acid, and a column packed with Raschig rings. 96% wt. sulfuric acid. The released hydrogen chloride gas is countercurrently dried in sulfuric acid. After drying, the hydrogen chloride gas was freed from entrained drops of sulfuric acid in a drop separator. The purified hydrogen chloride gas was absorbed in high purity microelectronics grade water with a resistivity of 18 megaohms / cm, which was filtered through a 0.2 micron filter. The hydrochloric acid obtained contained 36.7 wt. hydrogen chloride and had the following analysis:

i '?

Evaporator of less than 10 ° ³ % w / w, sulphates

4.10 “ ⁵ % by weight, sulphates 2.10” ⁵ % by weight, heavy metals less than 10 “ ⁴ % by weight, iron 2.10” ⁵ % by weight, arsenic less than 10 “ ⁶ % by weight, lithium less than 1O“ ⁰ wt.%, hydrogen 3.10 ⁵ wt.%, potassium 10 ^-5 · wt. magnesium, less than 10 “ ⁵ pens. wt.

Number of particles in 1 1 voluntary interval: 1 - 5 μτα - 8 946

5—25 μτα - 835 over 25 µm - 58

Example 2

The procedure of Example 1 was followed except that a saturated sodium chloride solution was placed in the flask instead of hydrochloric acid.

The hydrochloric acid obtained was 36.9% by weight. hydrogen chloride had the following analysis:

Ok evaporate less than 10 ^"3 wt., Sulphates S

10 " ⁵ % by weight, sulphates 3.10 ⁵ % by weight, heavy metals less than 10" ⁴ % by weight, iron 10 ⁵ % by weight, arsenic less than 10 ~ ⁶ pens. % by weight, lithium less than 10 " ⁶ % by weight, calcium 3.10 " ⁵ % by weight, sodium 5. .10-5 / _v wt., Potassium 2/10 ^"5 wt.%, Magnesium less than 10" ⁵ wt.

Number of particles per loyalty interval:

5—25 / tm - 1,210

1—- 5 μΐη - 5 537 above 25 μπι - 84

Example 3

The procedure of Example 1 was followed except that 5 g of silica gel was added to the aqueous hydrochloric acid solution, the iron content being reduced from 2.10 ^-5 % by weight. below 10 ~ ⁵ wt.

The hydrochloric acid obtained is 36.6% by weight. hydrogen chloride had the following analysis:

Evaporation of less than 10 ~ ³ % by weight, sulphates. 10 ~ ⁵ wt. sulphates of less than 10 ^δ per wash. wt. Heavy metals less than 10 ~ ⁴ pens. % by weight, iron less than 10 ^-5 % by weight, arsenic less than 10 ^-6 %, lithium less than 10 ^-6 % by weight, hydrogen 10 ~ ⁵ pere. % potassium, less than 10 ~ ⁵ wt.%, calcium 10 ~ ⁵ wt.%, magnesium less than ⁵ wt.%.

Number of particles in a size interval:

1 - 5 mm 7 458

5—25 μπι 1 128 over 25 μία 49

Claims (2)

Process for the production of hydrochloric acid for microelectronics comprising the stepwise addition of sulfuric acid to aqueous solutions of hydrochloric acid and / or chlorides, wherein the mixing and / or reaction heat maintains the obtained mixture in a boiling hydrogen chloride release characterized in that the hydrochloric acid is countercurrently dried by acid the hydrogen chloride obtained is stripped of the droplet separator, and the purified hydrogen chloride is absorbed in microelectronics grade water to an aqueous hydrochloric acid solution. 2. A process as claimed in claim 1, wherein impurities are adsorbed from aqueous solutions of chlorides and hydrogen chloride with silicates having active adsorption sites.