JP2800043B2 - Purification of impure aqueous hydrogen peroxide solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention is a highly purified hydrogen peroxide obtained by purifying an impure aqueous hydrogen peroxide solution and containing extremely small amounts of any of metal cations, anions and organic impurities. It relates to a method for obtaining an aqueous solution.

(Prior Art) An aqueous hydrogen peroxide solution is widely used not only as a reaction reagent but also in many fields such as bleaching and chemical polishing.
In recent years, in the field of semiconductor manufacturing, the use of aqueous hydrogen peroxide in fields such as cleaning and etching of wafers has increased, and accordingly, an aqueous solution of hydrogen peroxide of extremely high purity has been required.

That is, in the manufacture of semiconductors, particularly in the manufacture of VLSI, the storage capacity and the number of elements have recently increased and the integration has been increased, and the minimum pattern size has been extremely miniaturized accordingly. When impurities or fine particles are present in the aqueous hydrogen peroxide solution used for cleaning such an VLSI,
They adhere on the film, and the oxide film thickness becomes thin, SiO ₂
This causes the pressure resistance of the film to deteriorate. Further, when impurities or fine particles are diffused on the Si substrate, the leak current increases, and the life of the carrier is shortened, which leads to a decrease in the yield of LSI as a product and a deterioration in characteristics.

Therefore, in the production of semiconductors, there is a demand for the development of a high-purity aqueous hydrogen peroxide solution containing not only fine particles but also very little ions.

As described above, in the field of semiconductor manufacturing, impurities in chemicals used have an important effect on product quality. Therefore, it is desired that impurities be as low as possible. Particularly, a hydrogen peroxide aqueous solution used for cleaning is desired. Means that all kinds of metal cations are less than 5 ppb (μg / Kg), all kinds of anions are less than 10 ppb and organic impurities are extremely high purity of less than 5 ppm (mg / Kg) as total organic carbon. Is required.

On the other hand, hydrogen peroxide is currently produced industrially mainly by the automatic oxidation of anthraquinone (hereinafter, this method is referred to as "anthraquinone method"). The aqueous solution of hydrogen peroxide produced by the anthraquinone method contains a trace amount of organic impurities, and the amount is usually about 10 mg to 500 mg / total organic carbon.

Further, various metal cations of about 5 ppb to about 10 ppm and various anions of about 10 ppb to about 10 ppm are usually contained as impurities due to the production method, elution from storage devices, addition of stabilizers, and the like.

As a method for obtaining a purified aqueous solution of hydrogen peroxide by removing the above-described impurities, several methods described below have been conventionally known, and some of them are actually implemented.

(A) Japanese Patent Publication No. 28-3816 This publication describes a method in which an aqueous solution of hydrogen peroxide is brought into contact with a sulfonated aromatic hydrocarbon-based cation exchange resin to mainly remove metal cations.

(B) US Pat. No. 3,297,404 This US patent describes a method for removing anionic impurities in an aqueous hydrogen peroxide solution using an anion exchange resin having a quaternary ammonium group. Ammonium groups are described for use in the form of carbonates and / or bicarbonates.

(C) Japanese Patent Publication No. 46-26095 Japanese Patent Publication No. 46-26095 discloses the use of a resin having a network molecular structure obtained by polymerizing styrene and crosslinking with divinylbenzene and having no ion exchange group. A method for adsorbing and removing organic impurities in a hydrogen aqueous solution is described.

(D) Japanese Patent Publication No. 63-156004 This publication describes a method for adsorbing and removing organic impurities in an aqueous hydrogen peroxide solution using a halogen-containing porous resin having a true specific gravity of 1.1 to 1.3. .

However, even if the above-mentioned known purification method is used, it is not possible to obtain a high-quality aqueous hydrogen peroxide solution that can be used for manufacturing semiconductors, particularly LSIs. That is, a high-quality aqueous hydrogen peroxide solution in which any metal cation satisfies 5 ppb or less, any anion satisfies 10 ppb or less, and organic impurities satisfy 5 ppm or less is not achieved even by using the above-mentioned known method.

For example, according to the above-described method using a cation exchange resin, metal cation impurities can be removed, but a part of the SO ₃ H group, which is an exchange group of the resin, is deteriorated by use of hydrogen peroxide and becomes SO ₄ ion. As a result, the anion impurities increase rather.

The method of using the halogen-containing porous resin,
Although it is suitable as a method for removing organic impurities, a part of the halogen originating from the resin is eluted, and the anionic impurities increase instead.

On the other hand, a method for purifying an aqueous hydrogen peroxide solution by combining several types of ion exchange resins has also been proposed. For example, Polish Patent No. 55,378 describes a method in which a cation exchange resin, an anion exchange resin and a cation / anion mixed bed resin are contact-treated with an aqueous hydrogen peroxide solution in this order. Organic impurities cannot be removed.

As described above, it was impossible to obtain a high-quality aqueous hydrogen peroxide solution containing all of the metal cations, anions and organic impurities as described above in a certain amount or less by the conventionally known methods.

(Object of the Invention) Therefore, a first object of the present invention is to provide an aqueous solution of extremely high quality by purifying an aqueous solution of impure hydrogen peroxide.

A second object of the present invention is to provide a purification method for obtaining a high-quality aqueous hydrogen peroxide solution that can be used in the production of semiconductors, particularly LSIs.

Another object of the present invention is to provide any metal cations of 5 ppb or less and any anions of 10
An object of the present invention is to provide a purification method for obtaining a high-purity aqueous solution of hydrogen peroxide having a concentration of ppb or less and an organic impurity having a total organic carbon content of 5 ppm or less.

Still another object of the present invention is to provide a method for obtaining the above-mentioned high-quality aqueous hydrogen peroxide solution by industrially advantageous means.

Still other objects of the present invention will become more apparent from the following description.

(Means for Solving the Problems) According to the study of the present inventors, the object and advantages of the present invention are as follows: (1) a cation exchange resin layer and a halogen-containing porous resin layer. And (2) the halogen-containing porous resin layer, the cation exchange resin layer and the anion exchange resin layer in this order, or (3) the halogen-containing porous resin layer and the cation / anion mixture. It has been found that this is achieved by a method for purifying an aqueous solution of hydrogen peroxide, characterized in that the aqueous solution is passed through a bed resin layer in this order, and the aqueous solution is contacted with each resin.

The aqueous solution of impure hydrogen peroxide to be subjected to the purification method of the present invention may be obtained by any production method, but is preferably produced by the anthraquinone method. The anthraquinone method generally has a 2-
The alkylanthraquinone is hydrogenated in a water-insoluble solvent in the presence of a hydrogenation catalyst to form a corresponding anthrahydroquinone.After separating the catalyst, the original anthraquinone is regenerated by oxidation with oxygen or air, and hydrogen peroxide is removed. The crude hydrogen peroxide solution is obtained by extracting with water.

The crude hydrogen peroxide aqueous solution thus produced is purified or concentrated by evaporation under reduced pressure and rectification, and is generally about 10 to about
70% by weight, especially about 20 to about 60% by weight aqueous solution.

Although the aqueous hydrogen peroxide solution obtained in this way is considerably purified, it is caused by elution from stabilizers, reactors, piping, storage tanks, etc., in addition to organic impurities generated during the manufacturing process. Since it contains various types of kaotin and anions, it cannot be used for cleaning purposes in semiconductor production as it is.

That is, in an industrially produced aqueous hydrogen peroxide solution, in addition to organic impurities, for example, metal cations such as Al, Na, K, Ca, Fe or Cr, Cl ⁻ , Br ⁻ , PO ₄ ^3- or SO ₄ ^2-
And the like. These metal cations and anions are representative examples, and others are included in smaller amounts. However, according to the present invention, any metal cation and anion can be removed below the target value.

According to the present invention, an impure aqueous hydrogen peroxide solution to be purified is passed through each resin layer according to any one of the following (1) to (3), and is subjected to a contact treatment with each resin in each resin. Thereby, a high-quality aqueous hydrogen peroxide solution can be obtained.

(1) Cation exchange resin layer → halogen-containing porous resin layer → anion exchange resin layer (2) Halogen-containing porous resin layer → cation exchange resin layer → anion exchange resin layer (3) Halogen-containing porous resin layer → cation / Anion-mixed bed resin layer The purification method of the present invention is characterized in that an aqueous hydrogen peroxide solution is brought into contact with all three kinds of resins, a cation resin, an anion resin and a halogen-containing porous resin, and the order of the contact. doing. That is, the resin finally brought into contact is an anion exchange resin or an anion / cation mixed bed resin.

Thus, in the purification method of the present invention, the aqueous hydrogen peroxide solution may be passed through each resin layer according to any combination of the above (1) to (3). Accordingly, the object of the present invention can be achieved as long as any one of the above-mentioned (1) to (3) is maintained. It does not matter if additional ion exchange resin layers are combined. For example, a cation exchange resin contact treatment can be combined before the combination of (2) or (3).

In the purification method of the present invention, among the combinations of the above (1), (2) or (3), when there are many organic substances,
(2) is preferred in order to avoid contamination of the cation exchange resin with organic substances. When the concentration of each of the cation and anion is as low as 100 ppb or less, the method (3) is preferable because the number of columns is small and the impurities in the purified solution are small.

Hereinafter, the resin forming each resin layer and the contact conditions between the resin and the aqueous solution of hydrogen peroxide in each resin will be described in detail.

Cation exchange resin layer; The resin forming this resin layer is SO as an ion exchange group.
_ThreeThose having an H group are used. This cation exchange resin
Is generally a styrene-divinylbenzene cross-linked copolymer.
It is obtained by sulfonation with sulfuric acid.
You. This cation exchange resin is strongly acidic and
It is preferable that the resin has a high bridging property. For example, Amba
-Light 200C, 200CT, 252 and Diaion PK
Leeds (for example, PK224, PK228) and the like. this
These resins are generally commercially available in Na ion form,
When forming a layer, use a strong acid such as sulfuric acid or hydrochloric acid.
The aqueous solution is passed through and converted into the H ion form for use. H type
To convert to sulfuric acid or hydrochloric acid aqueous solution was passed through the resin layer
That is, it is carried out by a method in which pure water is passed through and sufficiently washed.
In addition, amber light H ion type like 200CH
Products that are commercially available
Can be.

The temperature at which an aqueous solution of hydrogen peroxide (hereinafter sometimes simply referred to as an aqueous solution) passes through the cation exchange resin is about 30 ° C.
Hereinafter, preferably, the range of -10 to 20C is appropriate. 30 ℃
Exceeding the ratio is not preferred because the rate of elution of ion exchange groups (SO ₃ H) increases. The space velocity of the aqueous solution passed through the resin layer is represented by the following formula, and is suitably in the range of about 1 to about 500, preferably about 20 to about 300.

In the cation exchange resin layer, the amount (Vol) of the aqueous solution to be brought into contact with the resin (Vol) depends on the concentration of the metal cation in the aqueous solution, but is generally about 200 to about 50,000 times, preferably about 500 times. A range of about 20,000 times is desirable.

The linear velocity of the aqueous solution passing through the cation exchange resin layer
LV (m / hr) is preferably in the range of about 1 to about 100 m / hr represented by the following formula.

Anion exchange resin layer The resin forming this resin layer can be a strong basic resin having a quaternary ammonium group, a weak basic resin having a tertiary ammonium group, or a vinylpyridine resin, but is preferably A strongly basic resin having a quaternary ammonium group is particularly preferable, and a resin having a carbonate or bicarbonate of a quaternary ammonium group is particularly preferable.

 The anion exchange resin described above is generally a styrene-diamine.
Chloromethylation of vinylbenzene cross-linked copolymer followed by amino
The amination can be carried out in particular.
Quaternary ammonium group
Is obtained. With anion exchange resin
As described above, it is strongly basic and crosslinkable.
Preferably, the resin is high. For example, Amberlite
IRA series (for example, IRA-900, IRA-904),
Ear ion PA series (eg PA316, PA318) etc.
Is mentioned. These resins are generally in the form of Cl ions.
It is commercially available.
Or by passing an aqueous solution of bicarbonate through carbonate ions or
Convert to ion form and use. Carbonate or bicarbonate
Conversion to the ON type is achieved by adding sodium carbonate or bicarbonate to the resin layer.
Thorium solution is passed through and then pure water is passed through.
It is performed by a method of washing with water.

The temperature at which the aqueous hydrogen peroxide solution is passed through the anion exchange resin layer is about 10 ° C. or less, preferably in the range of −10 ° C. to 5 ° C. If the temperature is higher than 10 ° C., hydrogen peroxide is liable to be decomposed, and air bubbles are accumulated in the resin layer to lower the purification degree, which is not preferable. The space velocity (SV) of the aqueous solution passed through the anion exchange resin layer is suitably in the range of about 10 to about 500 (1 / hr), preferably about 20 to about 300 (1 / hr). The amount (Vol) of the aqueous solution to be brought into contact with the resin (Vol) in the anion exchange resin layer is not constant depending on the concentration of the anion in the aqueous solution, but is generally about 200 to about 50,
A range of about 000 times, preferably about 500 to about 20,000 times is desirable.

Further, the linear velocity LV (m / hr) of the aqueous solution passing through the anion exchange resin layer is preferably in the range of about 4 to about 100 m / hr.

Cation / anion mixed bed resin layer; This resin layer is a mixed resin layer of a cation exchange resin and an anion exchange resin, wherein the weight ratio of the cation exchange resin and the anion exchange resin is about 1: 3 to about 3: 1, preferably about 1: 2 to about 2: 1 to form a layer with uniform mixing.

The temperature at which the aqueous hydrogen peroxide solution is passed through the mixed bed resin layer is about 10 ° C. or less, preferably in the range of -10 to 5 ° C. If the temperature is higher than 10 ° C., hydrogen peroxide is liable to be decomposed, bubbles are accumulated in the resin layer, and the purification degree is undesirably reduced. The SV of the aqueous solution passed through this resin layer is about 5 to about 300
(1 / hr), preferably about 10 to about 200 (1 / hr), and LV (m / hr) is about 4 to about 100 m / hr. The amount of aqueous solution with respect to the total volume of the mixed bed resin layer depends on the type and concentration of ions in the aqueous solution, but is generally about 100 times to about 3 times.
A range of about 0000 times, preferably about 200 times to about 10,000 times is suitable.

Halogen-containing porous resin; Examples of the halogen-containing porous resin include (i) a halide of a crosslinked polymer obtained from an aromatic monovinyl monomer and an aromatic polyvinyl monomer; (ii) a halogenated aromatic monovinyl monomer and an aromatic compound. Preferred examples thereof include a crosslinked polymer obtained from an aromatic polyvinyl monomer; and (iii) a halogenated aromatic monovinyl monomer, a crosslinked polymer obtained from an aromatic monovinyl monomer, and an aromatic polyvinyl monomer.

Explaining specific examples of each of the above monomers, examples of aromatic monovinyl monomers include styrene and vinyltoluene, examples of aromatic polyvinyl monomers include divinylbenzene and trivinylbenzene, and examples of halogenated aromatic monovinyl monomers include For example, monochlorostyrene and monobromostyrene are shown.

As the halide of the crosslinked polymer obtained from the aromatic monovinyl monomer and the aromatic polyvinyl monomer, for example, a styrene-divinylbenzene copolymer,
Chloride or bromide of styrene-trivinylbenzene copolymer or vinyltoluene-divinylbenzene copolymer is preferred. Such chlorination or bromination involves contacting the resulting copolymer of the above monomers with molecular chlorine or molecular bromine in the presence of a catalyst such as, for example, ferric chloride or boron fluoride. Can be performed. Of the above, halides of styrene-divinylbenzene copolymer are most suitable for the present invention.

The halogen-containing porous resin obtained as described above,
Suitably it contains about 10 to about 40% by weight, preferably about 25 to about 40% by weight, of the halogen, based on the dry resin. Further, the porous resin has continuous porosity, the degree of porosity is expressed in terms of specific surface area, about 200 to about 600 m ² / g, more preferably about 400
Advantageously it is about 600 m ² / g. The specific surface area is a value measured by the BHT method (N ₂ ). Further, it is advantageous that the porous resin has a continuous porosity based on the dry resin having a pore volume of about 0.3 to about 1 ml / g. This pore volume is a value measured by a mercury intrusion method.

The porous resin is desirably particles having an average particle size of about 0.1 to about 0.5 mm. This average particle size is about
It refers to the size of the sieve that passes through 10% by weight and leaves about 90% by weight on the mesh.

The halogen-containing porous resin has a true specific gravity of 1.
Those in the range of 1-1.3, preferably 1.1-1.2 are advantageously used. If the true specific gravity at the time of wetting exceeds 1.3, the adsorption capacity of the porous resin decreases, and the elution of halogen from the resin increases.

The temperature at which the aqueous solution of hydrogen peroxide passes through the halogen-containing porous resin layer is about 30 ° C. or less, preferably −10 to 20 ° C.
A range of ° C is appropriate. If the temperature exceeds about 30 ° C., the amount of halogen eluted is undesirably increased. The space velocity (SV) of the aqueous solution passed through this resin layer is from about 1 to about
A range of 50, preferably about 3 to about 30, is advantageous.

In the halogen-containing porous resin layer, the resin (Vo
l) The amount of aqueous solution to be brought into contact with (Vol)
It is not constant depending on the concentration of organic impurities in the aqueous solution, but is generally about 100 to about 10,000 times, preferably about 200 to about 3,0 times.
A range of 000 times is desirable.

The linear velocity LV (m / hr) of the aqueous solution passing through the halogen-containing porous resin layer is suitably in the range of about 1 to about 50.

Thus, according to the present invention, an aqueous solution containing usually about 10 to about 70% by weight, preferably about 20 to about 60% by weight, of hydrogen peroxide is passed through each of the resin layers, whereby the desired high purity is obtained. An aqueous hydrogen peroxide solution can be obtained.

It is preferable that each of the resins is filled in a column, and the aqueous solution is supplied into the column. The supply of the aqueous solution in each column may be performed continuously or discontinuously.

In the present invention, the measurement of impurities in the aqueous hydrogen peroxide solution is performed by the following method.

That is, cationic impurities are measured by flameless atomic absorption spectrometry (using AA670G type analyzer manufactured by Shimadzu Corporation), and anionic impurities are measured by ion chromatography (using QIC type analyzer manufactured by DIONEX). In addition, organic impurities were analyzed using a total carbon analyzer (TOM manufactured by Shimadzu Corporation).
C500).

According to the purification method of the present invention, the content of any metal cation is 5 ppb or less, and the content of any anion is 10 ppb.
b and an extremely high purity aqueous solution of hydrogen peroxide having an organic impurity content of 5 ppm or less, and the obtained aqueous solution can be used as a cleaning solution in the production of semiconductors, especially VLSI, or other Can be used in admixture with the above reagent.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 A styrene-divinylbenzene copolymer having a SO ₃ H type exchange group (trade name: Amberlite 200CH, manufactured by Organo Corporation) was used as a cation exchange resin, and a quaternary ammonium group was used as an anion exchange resin. A bicarbonate type of a strong basic resin having the following formula (trade name; Amberlite IRA-900, manufactured by Organo Corporation) was used. As the halogen-containing porous resin, a brominated styrene-divinylbenzene copolymer (trade name: Sepabeads SP207, manufactured by Mitsubishi Kasei Kogyo Co., Ltd., surface area: 400 m ² / g) was used.

Each of these resins is 10ml in inner diameter 10mmφ, length 30
The column was packed in a column of cm, and they were connected in series in the order of a cation exchange resin, a halogen-containing porous resin, and an anion exchange resin, and a 31% concentration (wt%) raw material aqueous hydrogen peroxide solution was passed. The liquid passing speed was 500 ml / hr, and the liquid temperature was 8 ° C.

The purification results are as shown in Table 1, and the cationic impurities 5p
Pb or less, anionic impurities of 10 ppb or less, and organic impurities of 5 ppm or less were achieved.

Example 2 The same resin as in Example 1 was used, except that the cation exchange resin and the anion exchange resin were mixed at a volume ratio of 1/1 and used as a cation / anion mixed bed resin. Halogen-containing porous resin and cation / anion mixed bed resin are 10mm in inner diameter and 30cm in length
Packed into a column containing halogen-containing porous resin, cation /
The anion-mixed bed resin was used in this order. Other conditions are the same as in the first embodiment.

The purification results are as shown in Table 1, and the cationic impurities 5p
Pb or less, anionic impurities of 10 ppb or less, and organic impurities of 5 ppm or less were achieved.

Comparative Example 1 In the same manner as in Example 1 except that the connection order of the columns in Example 1 was changed in the order of cation exchange resin, anion exchange resin, and halogen-containing porous resin, the same hydrogen peroxide aqueous solution as in Example 1 was used. Processing was performed.

The purification results are as shown in Table 1, and the cationic impurities 5p
Although pb or less and organic impurities of 5 ppm or less were achieved, Br ions increased, so that purification to anionic impurities of 10 ppb or less could not be performed.

Comparative Example 2 In the same manner as in Example 1 except that the connection order of the columns in Example 1 was changed to the order of the halogen-containing porous resin, the anion exchange resin, and the cation exchange resin, the same aqueous hydrogen peroxide solution as in Example 1 was used. Processing was performed.

The purification results are as shown in Table 1, and the cationic impurities 5p
pb less, since although organic impurities 5ppm or less is achieved SO ₄ ions is increased, it was not possible to purify the following anionic impurities 10 ppb.

Example 3 The same resin as in Example 1 was used as the halogen-containing porous resin, cation exchange resin and anion exchange resin. Each of these resins is packed in a column of 10 mm in inner diameter, 10 mm, and a length of 30 cm.
Connect cation exchange resin and anion exchange resin in this order
A 31% concentration (wt%) raw material hydrogen peroxide aqueous solution was passed.

The liquid passing speed and the liquid passing temperature were the same as in Example 1. Purification results were as follows: all cationic impurities shown in Table 1 were 5 ppb or less, and anions shown in Table 1 Impurities are 10ppb or less, organic impurities (total carbon content)
Was less than 5 ppm.

Claims (5)

(57) [Claims] 1. An impure aqueous hydrogen peroxide solution is added to (1) a cation exchange resin layer, a halogen-containing porous resin layer and an anion exchange resin layer in this order, or (2) a halogen-containing porous resin layer and a cation exchange resin layer. And (3) passing through the halogen-containing porous resin layer and the cation / anion mixed bed resin layer in this order, and contacting the aqueous solution with each resin. A method for purifying an aqueous hydrogen peroxide solution. 2. The purification method according to claim 1, wherein the cation exchange resin is a cation exchange resin having an SO ₃ H group as an exchange group. 3. The method according to claim 1, wherein said anion exchange resin is a quaternary ammonium group as an exchange group, and said group has a form of carbonate or bicarbonate. 4. The method according to claim 1, wherein said halogen-containing porous resin is a halogen-containing porous resin containing 10 to 40% by weight of halogen. 5. The halogen-containing porous resin according to claim 1, wherein said porous resin is 200 to 600 m ^2.
The purification method according to claim 1, which is a halogen-containing porous resin having a specific surface area of / g.