JPH03153891A - Electrolytic producing apparatus for quaternary ammonium hydroxide - Google Patents

Abstract

PURPOSE:To provide the producing apparatus which efficiently obtain the above high purity oxide while removing the acids of the respective chambers in an anion exchange resin column by consisting the apparatus of an electrolytic cell having a diaphragm between an anode and cathode and the above-mentioned column connected with a circulating passage which can circulate the anolyte or intermediate chamber liquid on the outside of the electrolytic cell. CONSTITUTION:The electrolytic cell 1 is constituted of a cathode plate 2, an anode plate 3, a cation exchange membrane 4, an anode chamber 5, a cathode chamber 6, an anolyte liquid pool 11, an anolyte discharge port 12, etc. The chamber 5 connects in series to the liquid pool 11 and a circulating pump P1 via the circulating passages C1, C2 and circulates the anolyte during the electrol ysis time. The supply 13 of quaternary ammonium salt is continuously carried out to the liquid pool 11 and the quaternary ammonium cation supplied to the chamber 5 is passed through the membrane 4 by the flow of current, by which the cation is moved to the chamber 6 to form the quaternary ammonium hydroxide. The anolyte is continuously discharged from the discharge port 12, by which the material balance is matched.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an apparatus for producing an aqueous solution of quaternary ammonium hydroxide, and is particularly used as a wafer cleaning solution in the manufacturing process of ICs and LSIs in the electronics and semiconductor industries. , an apparatus for producing quaternary ammonium hydroxide used in etching solutions, developing solutions, etc.

[Prior Art and Problems to be Solved by the Invention] Quaternary ammonium hydroxide is a strong basic organic compound that is a useful chemical in chemical reactions such as phase transfer catalysts and standard solutions for non-aqueous titration. It is used as a processing agent for cleaning semiconductor substrates, etching, and developing positive resists in the manufacture of LSIs.

Harmful impurities in quaternary ammonium hydroxide include:
L i % N a s K S F e % N i
%A'sCation such as Cr, Zn, C1, Br,
There are 1st class anions, etc. As the degree of integration of semiconductors increases, further reduction of harmful impurity ions in quaternary ammonium hydroxide is required.

The general method for producing this quaternary ammonium hydroxide is as follows:
A trialkylamine and an alkyl halide are reacted to form a quaternary ammonium salt, which is then brought into contact with silver hydroxide to precipitate silver halide, or a quaternary ammonium salt is formed by contacting with a 01 (type anion exchange resin). There is a way to make it into an oxide.

In the former case, the cost of silver hydroxide is high, and in the latter case, the amount of sodium ions increases due to the contamination of NaOH used for regeneration.
Further, there are drawbacks such as difficulty in completely removing halogen ions. As a countermeasure to this problem, many methods have been proposed for producing quaternary ammonium hydroxide by electrolyzing quaternary ammonium salts, but these methods have not yet reached a complete technological level.

When producing quaternary ammonium hydroxide from quaternary ammonium salt by electrolysis, at least one diaphragm is used to prevent mixing of the anolyte and catholyte. The structure consists of a two-chamber electrolytic cell consisting of an anode chamber, a cation exchange membrane, and a cathode chamber with a cation exchange membrane as a diaphragm, and a pair of opposing electrode plates, with an anion exchange membrane on the anode side and a cation exchange membrane on the cathode side. This is a three-chamber electrolytic cell, etc., in which two chambers are placed facing each other.

In the case of a two-chamber electrolyzer, the raw material quaternary ammonium salt is supplied to the anode chamber, and when electrolysis is performed by applying DC voltage, the quaternary ammonium cation passes through the cation exchange membrane and moves to the cathode chamber. Then, water splitting takes place and hydrogen gas and OH
- is produced and a quaternary ammonium hydroxide solution is obtained.

In the anode chamber, OH- generally becomes water and oxygen gas through an anode reaction, and acid is accumulated in the anode chamber. The acids are sulfuric acid, nitric acid,
In the case of inorganic acids such as phosphoric acid and carbonic acid, and organic acids such as formic acid and acetic acid, the hydrogen ions of nucleic acids move to the cathode chamber faster than quaternary ammonium cations, passing through the cation exchange membrane to the cathode. room and significantly reduces the production efficiency of quaternary ammonium hydroxide.

The acid produced in the anode chamber also diffuses into the cathode chamber through the diaphragm and mixes with the quaternary ammonium hydroxide, reducing the purity of the quaternary ammonium hydroxide.

Also, if the acid concentration in the anode chamber is high, corrosion of the anode material increases.

JP-A No. 57-155390 (Mitsubishi Yuka@), JP-A No. 6
No. 0-100690 (Tama Chemical Industry ■), JP-A-61-
No. 170588 (Tama Chemical Industry ■), JP-A-63-24
No. 080 (Tama Chemical Industry ■), JP-A-63-57790
No. (Mitsubishi Gas Chemical ■), JP-A No. 1-87794 (Tokuyama Soda@), and other prior art techniques have the drawbacks of the two-chamber method.

To overcome this drawback, when the anolyte is neutralized with an alkali such as sodium hydroxide, sodium ions pass through the cation exchange membrane, move to the cathode chamber, and accumulate in the catholyte. Reduces the purity of quaternary ammonium hydroxide.

In the case of a three-chamber electrolyzer, the quaternary ammonium salt as a raw material is supplied to an intermediate chamber with an anion exchange membrane and a cation exchange membrane on both sides, and is converted into quaternary ammonium cations by applying DC voltage and performing electrolysis. passes through the cation exchange membrane and moves to the cathode chamber, where water is split and hydrogen gas and OH-
is generated and an aqueous quaternary ammonium hydroxide solution is obtained.

The counter anion of the quaternary ammonium cation in the intermediate chamber passes through the anion exchange membrane to the anode chamber, where the acid accumulates. In this case, since the hydrogen ion transport number of the anion exchange membrane is high, some of the hydrogen ions generated in the anode chamber pass through the membrane and move to the intermediate chamber, and further pass through the cation exchange S to the cathode chamber. It migrates and significantly reduces the production efficiency of quaternary ammonium hydroxide. To prevent this drawback,
When the anolyte is neutralized with an alkali such as sodium hydroxide,
Sodium ions accumulate, pass through an anion exchange membrane and a cation exchange membrane in order, and move to the cathode chamber, reducing the purity of the quaternary ammonium hydroxide.

JP-A-1-87793 (Tokuyama Soda A), JP-A-1-
Prior art such as No. 87796 (Tokuyama Soda@) As prior art for inserting electrolysis, JP-A No. 62-213686 (Tokuyama Soda 01) and JP-A No. 1-87795 (Tokuyama Soda @)
There is. In the former method, a cation exchange membrane group consisting of two or more cation exchange membranes is arranged between an anode and a cathode, and a quaternary ammonium salt is supplied to the anode side of the cation exchange membrane group to perform electrolysis. , a method of obtaining quaternary ammonium hydroxide from the cathode chamber, but a problem with acid occurred in the anode chamber, and the method described in 2.
It has the same drawbacks as the chamber method. In addition, in the latter case, at least two cation exchange membranes are arranged between the anode and the cathode to form a cathode chamber,
In electrolysis, the electrolytic cell has an intermediate chamber and an anode chamber, a quaternary ammonium salt aqueous solution is supplied to the anode chamber, quaternary ammonium hydroxide is present in the intermediate chamber, and the quaternary ammonium hydroxide aqueous solution is taken out from the cathode chamber. This is a method for producing quaternary ammonium hydroxide, characterized in that the concentration of the quaternary ammonium salt mixed in the intermediate chamber is maintained at 1710 or lower than the concentration of the quaternary ammonium salt in the anode side chamber adjacent to the intermediate chamber. This method is not economical because the acid generated in the anode chamber moves to the intermediate chamber, and the acid is neutralized with quaternary ammonium hydroxide, which consumes a large amount of quaternary ammonium hydroxide.

JP-A-1-87792 (Tokuyama Soda ■), JP-A-1-1
Prior art techniques such as No. 08388 (Tokuyama Soda ■) have the drawbacks of the three-chamber method because an anion exchange membrane faces the anode chamber and acid is present in the anode chamber.

As mentioned above, even if a conventional electrolytic cell with two, three, or four or more chambers is used, acid accumulates in the anode chamber, making it extremely difficult to efficiently produce a high-purity quaternary ammonium hydroxide aqueous solution. It is.

The present invention provides an electrolytic production device that efficiently produces a highly pure quaternary ammonium hydroxide aqueous solution while removing acid with an anion exchange resin column.

That is, the electrolytic manufacturing apparatus of the present invention has an anode and a cathode.

In the case of a two-chamber electrolytic cell, the quaternary ammonium salt is supplied to the anode chamber, and electrolysis is performed by applying a DC voltage to produce a quaternary ammonium hydroxide aqueous solution in the cathode chamber, and in the anode chamber. Acid is supplied to the soil intermediate chamber, and by applying a DC voltage to perform electrolysis, a quaternary ammonium hydroxide aqueous solution is obtained in the cathode chamber, and acid is generated in the anode chamber.

As a diaphragm for the electrolytic cell, two or more cation exchange membranes, one anion exchange membrane, and two or more cation exchange membranes for one pair of electrodes, and a cation exchange membrane and an anion exchange membrane for the others. Even when a large number of membranes are used, the configuration of the anode chamber is either the cation exchange membrane facing the anode or the anion exchange membrane facing the anode, and the configuration of the anode chamber is such that the two-chamber electrolytic cell or the three-chamber electrolytic cell are It can be carried out according to the format.

The interchamber liquid is maintained in and above the anode chamber through the respective circulation passages, and the quaternary ammonium cations are transferred to the cathode chamber through the diaphragm to efficiently produce high-purity quaternary ammonium hydroxide.

This is indicated by quaternary ammonium, which is a raw material used in the apparatus of the present invention. (R+, RZ, R3 and R4 in the formula may be the same or different, and each represents an alkyl group having 1 to 8 carbon atoms, an alkoxyalkyl group having 2 to 9 carbon atoms, or an alkyl group having 2 to 9 carbon atoms, or
Xe represents an acid group) The above R3 to R4 are, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group,
Alkyl groups such as methoxyethyl groups, alkoxyalkyl groups such as methoxypropyl groups, phenyl groups, tolyl groups,
Examples include aromatic groups such as xylyl groups and derivatives thereof.

Xe is, for example, nitrate radical (NOx), sulfuric acid full (
so, ), carbonate radical (CO3-), phosphate radical (PO, --
-), formic acid radicals (HCOO----'), acetic acid radicals (CH3COO-), methyl carbonate radicals (COi C
H3) Methyl sulfate group (S Oa G Hz −), trifluoromethanesulfonic acid group (CF 3 SO3 ~
), which is a penze organic acid root. However, among the inorganic acid roots, halogen ions such as chloride ions, bromide ions, and iodine ions are excluded from the root-free acid roots because quaternary ammonium cations are chemically degraded by halogen molecules generated at the anode. Among the anions, particularly preferred are sulfate groups,
Methyl sulfate roots, etc.

(Example) The invention is not limited to this example.

Figure 1 shows a case where a two-chamber electrolytic cell is used; 1 is an electrolytic cell, 2 is a cathode plate, 3 is an anode plate, 4 is a cation exchange membrane, 5 is an anode chamber, 6 is a cathode chamber, 7 is an anode terminal, 8 is a cathode terminal, 9 is an anode chamber inlet, IO is an anode chamber outlet, 11 is an anolyte reservoir, and 12 is an anolyte drain.

The anode chamber 5 is connected to the anode reservoir 1 via circulation passages C1 and C2.
1. It is connected in series with a circulation pump Pi, and the anolyte is circulated during the electrolysis time. The anolyte reservoir 11 continuously supplies quaternary ammonium salt from the raw material supply port 13, and the quaternary ammonium cations supplied to the anode chamber pass through the anode exchange membrane 4 and become the cathode. The mixture moves to chamber 6, where quaternary ammonium hydroxide is produced. The anolyte can be continuously extracted from the anolyte outlet 12 to balance the mass balance.

14 is an anion exchange resin column, 14R is an anion exchange resin, 15 is an inlet of the anion exchange resin column, 16 is an outlet of the anion exchange resin column, and 17 is a deoxidizing liquid reservoir.

The anode liquid reservoir 11 is connected in series with the circulation passages C3 and C4, the anion exchange resin tower 14, the deoxidizing liquid reservoir 17, and the circulation pump P2, and the anion exchange resin 14R, which has been regenerated with alkali and washed with water, is used as an anode. The acid in the liquid is removed, and the anolyte from which the acid has been removed is sent to the anolyte reservoir 11. It is preferable to repeat these operations continuously to maintain the pH of the anolyte in the anode chamber 5 at 1 or higher.

When the anion exchange resin 14R, which has been regenerated with alkali and washed with water, continues to come into contact with the acid in the anolyte, the anion exchange resin 14
R reaches a breakthrough point and acid begins to leak into the liquid at the anion exchange resin column outlet 16. At that point, the aqueous alkaline solution for regeneration is supplied from the anion exchange resin tower regeneration liquid inlet 18, which stops the flow of liquid to the anion exchange resin tower 14 and regenerates the anion exchange resin 14R. 14R is regenerated, and the regenerated waste liquid is sent to the anion exchange resin tower regenerated waste liquid outlet 1.
It is discharged from 9. After the regeneration is completed, washing water is supplied from the anion exchange resin tower washing water inlet 20 to push out the regenerated waste liquid in the anion exchange resin tower I4, and is disposed of from the anion exchange resin tower washing waste liquid outlet 21. After cleaning, the anolyte reservoir 11, circulation passages C3 and C4, and anion exchange resin column 1 are returned.
4. The acid in the anolyte is removed again in the circulation circuit of the deoxidizing liquid reservoir 17 and circulation pump P2. The adsorption regeneration operation of the anion exchange resin tower 14 is performed in accordance with a normal ion exchange operation.

Ion exchange may be performed in a batch manner or in a continuous manner.

The cathode chamber 6 is connected in series with the circulation passages C5 and C6, the catholyte reservoir 22, and the circulation pump P3, and the catholyte is circulated during electrolysis, and a portion is continuously extracted from the product extraction port 24. It will be done. Water may be supplied from the water supply port 23 in order to adjust the concentration of quaternary hydroxide in the catholyte.

FIG. 2 is an example in which a three-chamber electrolytic cell is used.

That is, 1 is an electrolytic cell, 2 is a cathode plate, 3 is an anode plate, 4 is a cation exchange membrane, 5 is an anode chamber, 6 is a cathode chamber, 7 is an anode terminal,
9 is the anode chamber inlet, and 10 is the anolyte outlet, which are the same as in FIG.

The difference from Fig. 1 is that 25A is an intermediate chamber liquid reservoir, and 28A is
29A is the intermediate chamber entrance, and 29A is the intermediate chamber outlet.

The intermediate chamber 25A includes circulation passages C7 and C8, and an intermediate chamber liquid reservoir 27.
A, I ring pump P5 is connected 3% in series, and the intermediate chamber liquid is circulated during the electrolysis time. In the intermediate chamber liquid reservoir 27A,
The quaternary ammonium salt is continuously supplied from the raw material supply port 30A. As a result of the flow, it passes through the anion exchange membrane 26A and moves to the anode chamber 5, where it becomes an acid. The intermediate chamber liquid can be continuously extracted from the intermediate chamber liquid outlet 31A to balance the material balance. 11
The difference between Figure 2 and Figure 1 with respect to 21 is 13.
There is only A. 13 in FIG. 1 is a raw material supply port, whereas 13A in FIG. 2 is a supply port for adjusting the composition of the anolyte.

The acid generated in the anode chamber is adjusted to the pH of the septum using the same method as shown in Figure 1.
may be maintained at 1 or higher.

Increasing the electrical conductivity of the anolyte in the anode chamber 5 in FIG.
In order to reduce the voltage, it is preferable to add a neutral salt that is not oxidized in the anode chamber. The cation of the neutral salt is preferably a quaternary ammonium cation, particularly a quaternary ammonium cation that is the same as the cation of the target quaternary ammonium hydroxide. Acid removal using anion exchange resin
Since this is an anion exchange treatment for only anions, the cations of the neutral salt are circulated to the anode chamber without being adsorbed. An example of the neutral salt is represented by the above formula (11).

The catholyte system in Figure 2 is 2.6.4.22.23.24,
C5, C6, P3, and P4 are the same as the catholyte system in FIG.

The pH of the anolyte in the anode chamber in Figures 1 and 2 is preferably maintained at 1 or higher, but this is due to the difference between the amount of acid produced in the anode chamber and the amount of acid removed in the anion exchange resin column. Achieved through balance. When the pH of the anode chamber becomes 1 or less, the ratio of hydrogen ions/quaternary ammonium cations in the anode chamber increases, and the amount of hydrogen ions moving to the cathode chamber increases, which is not desirable or undesirable. The pH of the anode chamber is more preferably 4 or more, and if necessary, the pH of the anode chamber can be raised to 7 or more using a strongly basic anion exchange resin.

The flow of liquid in each chamber through the anode chamber, cathode chamber, and intermediate chamber is as follows:
It is preferable that the flow be uniform, and it is preferable to control the flow in each chamber by changing the number, size, shape, arrangement, etc. of the liquid inlet and liquid outlet of each chamber.

The current density of the electrolytic cell is generally in the range of 1 to 50 A/d+w'', and the temperature inside the cell is set in the range of room temperature to 90°C.

The concentration of the quaternary ammonium salt in the intermediate chamber of the two-chamber electrolytic cell and the three-chamber electrolytic cell is preferably 60% by weight or less, preferably 5 to 401i1
%. The concentration of quaternary ammonium hydroxide in the cathode chamber is usually adjusted to 5-20%.

As the electrode material used in the present invention, for example, platinum, platinum-coated titanium, carbon, high-purity graphite electrode, etc. are used as the anode. In addition, as a cathode, alkali-resistant 5
US316, platinum, Raney nickel, etc. are used. The electrodes are conveniently plate-shaped, but may also be mesh-shaped to increase the electrode area.

The anion exchange resins used in the present invention include weakly basic and strongly basic anion exchange resins.

Among these, weakly basic anion exchange resins are particularly preferred.

The reason for this is that when regenerating an anion exchange resin that has adsorbed the acid in the anolyte, weakly basic anion exchange resins are easier to regenerate than strongly basic anion exchange resins, and the regeneration ratio is higher. This is because it is small and economical. A further advantage is that the pH of the anolyte can be maintained between 1 and 5 even if the regeneration rate of the anion exchange resin does not reach 100%.

As the alkali used for regenerating the anion exchange resin, caustic soda, caustic potash, etc. are usually used, but volatile aqueous ammonia is preferable.

The strongly basic anion exchange resin used in the present invention is an l-type resin that is polymerized using styrene, phosphor, V, and B as raw materials to produce a granular resin matrix, which is then chloromethylated, and then quaternized with trimethylamine. resin, a type resin quaternized with dimethylaminoethanol, etc. Examples include DOWEX-1, DOWEX-2, Amberlite IRA-400, Amberlite IRA-410, Diaion SA-10A, and Diamondion 5A-2OA.

The weakly basic anion exchange resin used in the present invention includes those having a primary amine, a secondary amine, and a tertiary amine, such as DOWEX 44, Amberlite IRA, etc.
-93, Amberlight ■RA-94, Diamond Ion W
A-30 etc.

As the cation exchange membrane used in the present invention, a hydrocarbon-based polymerized cation exchange membrane or a perfluorocarbon-based cation exchange membrane is used. Among these, perfluorocarbon-based cation exchange membranes are preferred because they have excellent heat resistance and oxidation resistance. Examples of the cation exchange membrane used in the present invention include Aciplex-1 manufactured by Asahi Kasei Corporation.
01, Naphyllon #415 manufactured by DuPont, Neocepta CL-257 manufactured by Tokuyama Soda ■, Selemion C manufactured by Asahi Glass Industries ■
There are MVs etc. Examples of the anion exchange membrane used in the present invention include Aciplex A-1OL manufactured by Asahi Kasei Corporation.
AV-47 manufactured by Tokuyama Soda ■, Ceremion A manufactured by Asahi Glass Industries ■
There are MVs etc.

The water used in the present invention is highly pure and has a purity of >4=Y-sr★(・-0).Also, surfaces that come into contact with water, such as electrolytic cells, anion exchange resin towers, piping, and pumps, should be free from corrosion and electricity. Take sufficient measures to prevent metal ions from eluting due to erosion, etc.;
[Effects of the Invention] As described in detail above, the apparatus for electrolytically producing an aqueous solution of quaternary ammonium hydroxide of the present invention includes an electrolytic cell having at least one diaphragm, and an electrolytic cell having a quaternary ammonium hydroxide aqueous solution. It produces hydroxide. Its advantages are +1) Since the pH of the liquid in the anode chamber and the -M intermediate chamber can be maintained high, in the case of a two-chamber electrolyzer, the hydrogen ion transfer number of the cation exchange membrane in contact with the anolyte is low, and therefore the fourth The ammonium cation has a high transference number, and it is possible to produce quaternary ammonium hydroxide with high current efficiency. Also, 3
In the case of a chamber electrolyzer, the transport number of anions in contact with the anolyte is low, and therefore the concentration of hydrogen ions in the intermediate chamber is small, so the quaternary ammonium in the cation exchange membrane in contact with the cathode chamber is low. The transference number of the cation becomes high, and as a result, it is possible to produce quaternary ammonium hydroxide with high current efficiency.

(2) Since the acid concentration in the anode chamber is low, in the case of a two-chamber electrolyzer, the amount of acid that moves from the anode chamber through the cation exchange membrane to the cathode chamber by diffusion, and in the case of a three-chamber electrolyzer, The amount of diffusion of acid that moves from the anode chamber through the anion exchange membrane to the intermediate chamber and further from the intermediate chamber through the cation exchange membrane to the cathode chamber is also reduced. Therefore, the concentration of acid radicals in the aqueous solution of quaternary ammonium hydroxide produced in the cathode chamber is reduced, making it possible to produce a highly purified product of quaternary ammonium hydroxide.

(3) Since the pH of the anode chamber can be maintained high, the acid concentration in the anode chamber is low, and the anode material TIA6! k is further reduced.

As described above, by using the electrolytic device of the present invention, the impurities of harmful cations and anions are extremely small, and it is possible to produce a high-purity electrolytic device that can be used for cleaning wafers, developing resist films, etc. in the semiconductor manufacturing process. It is possible to produce a tetraammonium hydroxide aqueous solution with high current efficiency, high productivity, and at low cost.

[Brief explanation of the drawing]

1 and 2 are flow sheets showing an embodiment of the apparatus of the present invention. In the drawings, 1... Electrolytic cell, 4... Cation exchange membrane, 5... Anode chamber, 6... Cathode chamber, 14... Anion exchange resin column, 14R... Anion Ion exchange resin, 25A...intermediate chamber, 26A...anion exchange membrane.

Claims (1)

[Claims] (1) An electrolytic cell having at least one diaphragm between an anode and a cathode, and at least one diaphragm installed outside the electrolytic cell.
quaternary ammonium water, characterized in that the anion exchange resin tower is connected to a circulation passage for circulating the anolyte of the electrolytic cell or the anolyte and the intermediate chamber liquid, respectively. Oxide electrolytic production equipment.