JPH0977504A - Purifying method of hydrogen peroxide aqueous solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain a highly purified hydrogen peroxide aq. solution by increasing the solubility of foam generated by the decomposition of hydrogen peroxide at the time of purifying, suppressing the size of foam, efficiently performing the removal of foam from a purification column and enabling to stably pass a solution. SOLUTION: In this method for purifying hydrogen peroxide or an aq. solution containing hydrogen peroxide by using the purification column in which packing materials are packed, hydrogen peroxide or the aq. solution containing hydrogen peroxide is purified while applying pressure to the upper part of the purification column.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purification method for removing impurities in a hydrogen peroxide solution or an aqueous solution containing hydrogen peroxide. The highly purified hydrogen peroxide solution or the aqueous solution containing hydrogen peroxide according to the present invention is particularly preferably used for cleaning a semiconductor substrate such as a silicon wafer.

[0002]

2. Description of the Related Art A basic or acidic aqueous hydrogen peroxide solution is widely used for cleaning silicon wafers, and as the density of integrated circuits increases, there is a strong demand for higher cleaning liquid purity. Therefore, the hydrogen peroxide solution used for this purpose is also required to have an extremely high purity, and at present, the organic impurities in the hydrogen peroxide solution are 10 ppm or less and the metal impurities are 1 ppb.
The following are required: Generally, as a method for removing impurities in an aqueous hydrogen peroxide solution, a treatment with an ion exchange resin, a chelate resin, an adsorption resin, or the like is generally known. When it is carried out, a flow method (column method) which is excellent in operability and has high removal efficiency is generally used.

[0003]

When hydrogen peroxide or an aqueous solution containing hydrogen peroxide is purified by a column method using various packings, bubbles unique to hydrogen peroxide are generated due to self-decomposition. Since the bubbles are generated and adhere to the periphery of the resin, there arises a problem that the purification efficiency, that is, the efficiency of removing impurities is reduced.

[0004]

[Means for Solving the Problem] The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, it is effective to purify while increasing the solubility of bubbles generated by decomposition of hydrogen peroxide, and particularly, the purification column. It has been found that it is extremely effective to apply pressure to the upper part of the, and the present invention has been completed. That is, by applying pressure to the upper part of the purification tower, it is possible to increase the solubility of bubbles generated by the decomposition of hydrogen peroxide,
The amount of foam can be reduced. In addition, since the size of bubbles can be suppressed to be small and bubbles can be efficiently removed from the purification tower, when the contact area between the resin used for purification and the hydrogen peroxide solution does not apply pressure. Therefore, the impurities can be removed more efficiently. Here, the upper part of the purification column indicates the inlet side in the case of the downward flow and the outlet side in the case of the upward flow. The pressure applied to the upper part of the purification tower is not particularly limited as long as it can increase the solubility of bubbles due to decomposition and can suppress the size of bubbles, but preferably 0.5 Kg / c.
m ² or more is preferable.

In the purification method of the present invention, the operating temperature is not particularly limited, but it is preferably -30 to 40 ° C, more preferably -25 to 25 ° C, further preferably -5 to 15 ° C. By operating at a low temperature, the solubility of bubbles is further increased, more stable operation is possible, and impurities can be removed more efficiently. It is also possible to suppress the deterioration of the filling material and maintain the activity of the filling material for a longer time. The packing used for purification is not particularly limited as long as it can remove impurities in hydrogen peroxide water, but generally, an ion exchange resin, a chelate resin, and an adsorption resin are preferably used. It is also possible to use these resins in combination, and there is no particular limitation on the number of combinations (the number of purification columns) and the order of combination.

The ion exchange resins include cation exchange resins and anion exchange resins, and the cation exchange resins preferably have SO ₃ H groups as ion exchange groups. This cation exchange resin is generally obtained by sulfonation of a styrene-divinylbenzene crosslinked copolymer with sulfuric acid, and it is preferable that the cation exchange resin is strongly acidic. On the other hand, as the anion exchange resin, a strongly basic resin having a quaternary ammonium group,
A weakly basic resin having a quaternary ammonium group or a vinyl pyridine-based resin is preferable, but a strongly basic resin having a quaternary ammonium group is preferable, and a carbonate of a quaternary ammonium group or It is a resin containing bicarbonate. Further, it is more preferably strongly basic. As the chelate resin, any resin having a chelating ability for metal ions, such as iminodiacetic acid type, polyamine type, phosphonic acid type, and N-methylglucamine type, can be used. Particularly preferred are phosphonic acid type chelate resins and N-methylglucamine type chelate resins, and more preferred resins are iminophosphonic acid type chelate resins or iminodiphosphonic acid type chelate resins.

The adsorbing resin is an insoluble three-dimensional crosslinked polymer having macropores, has no functional group such as an ion exchange group, has a large specific surface area, and has a va
A nonpolar porous adsorption resin or a halogenated modified porous adsorption resin that adsorbs various organic substances by the Nder Waals force is preferable. As the nonpolar porous adsorption resin, a styrene-divinyl copolymer, a polymer such as an acrylic acid ester, a methacrylic acid ester or vinyl pyridine is used. Further, as a preferable example of the halogenated modified porous adsorption resin, a brominated styrene-divinylbenzene copolymer can be mentioned. The concentration of hydrogen peroxide in hydrogen peroxide or an aqueous solution containing hydrogen peroxide, which is a raw material for purification, is not particularly limited, but is preferably 90% by weight or less, more preferably 70% by weight or less. Examples of the present invention will be shown below.

[0008]

【Example】

Example 1 A 31% by weight stock solution of hydrogen peroxide containing 10 ppm of total phosphoric acid radicals as an impurity was used as an anion exchange resin Amberlite I.
RA-400 (bicarbonate type, manufactured by Organo Corporation) 20 m
The solution was passed through a Teflon column having an inner diameter of 15 mm and a length of 30 cm filled with 1 at a temperature of 5 ° C. in a descending flow. At this time, squeezing was applied to the lower part of the column, and liquid was passed through so that a pressure of 1 Kg / cm ² was applied to the upper part of the column. During the passage, stable passage was possible, and the total phosphate group in the hydrogen peroxide solution after purification was 0.1 ppm or less.

Comparative Example 1 A 31% by weight aqueous solution of hydrogen peroxide containing 10 ppm of total phosphoric acid radicals as an anion was used as an anion exchange resin Amberlite I.
RA-400 (bicarbonate type, manufactured by Organo Corporation) 20 m
The solution was passed through a Teflon column having an inner diameter of 15 mm and a length of 30 cm filled with 1 at a temperature of 5 ° C. in a descending flow. At this time, no particular squeezing was applied to the lower part of the column, and no pressure was applied to the upper part of the column (0.3 Kg / cm ² or less) to pass the liquid. During liquid passing,
The generated foam adhered to the resin and the inner wall of the column and remained in the purification tower, so that stable liquid passing treatment could not be performed. The total phosphate group in the hydrogen peroxide solution after purification was 2 ppm.

Example 2 A 60 wt% stock solution of hydrogen peroxide containing iron 5 ppb as an impurity was added to a chelating resin Diaion CRA-100 (iminomethylenephosphonic acid type, manufactured by Mitsubishi Chemical Corporation) 20 m.
The solution was passed through a Teflon column having an inner diameter of 15 mm and a length of 30 cm filled with 1 at a temperature of 5 ° C. in a descending flow. At this time, squeezing was applied to the lower part of the column, and liquid was passed through so that a pressure of 1 Kg / cm ² was applied to the upper part of the column. During the passage of the liquid, stable passage can be performed, and the iron in the hydrogen peroxide water after purification is less than 0.
It was 1 ppb or less.

Comparative Example 2 A 60 wt% stock solution of hydrogen peroxide containing 5 ppb of iron as an impurity was added to a chelating resin Diaion CRA-100 (iminomethylenephosphonic acid type, manufactured by Mitsubishi Chemical Corporation) 20 m.
The solution was passed through a Teflon column having an inner diameter of 15 mm and a length of 30 cm filled with 1 at a temperature of 5 ° C. in a descending flow. At this time, no particular squeezing was applied to the lower part of the column, and no pressure was applied to the upper part of the column (0.3 Kg / cm ² or less) to pass the liquid. During liquid passing,
The generated foam adhered to the resin and the inner wall of the column and remained in the purification tower, so that stable liquid passing treatment could not be performed. Iron in the hydrogen peroxide solution after purification was 1.5 ppb.

Example 3 A 31 wt% stock solution of hydrogen peroxide containing 40 ppm of total organic carbon as an impurity was adsorbed on resin SepaBeads SP207 (bromination-modified styrene-divinylbenzene cross-linked copolymer, specific gravity 1.2, Mitsubishi Chemical Corporation. )) Teflon column having an inner diameter of 15 mm and a length of 30 cm filled with 20 ml was passed at a temperature of 10 ° C. in a downward flow. At this time, squeezing was applied to the lower part of the column, and liquid was passed through so that a pressure of 1.5 Kg / cm ² was applied to the upper part of the column. No generation of a short circuit was observed during the passage of liquid, and stable passage of liquid was possible, and the total amount of organic carbon in the hydrogen peroxide solution after purification was 5 ppm.

Comparative Example 3 A 31 wt% stock solution of hydrogen peroxide containing 40 ppm of total organic carbon as an impurity was adsorbed on a resin SepaBeads SP207 (bromination-modified styrene-divinylbenzene cross-linked copolymer, specific gravity 1.2, Mitsubishi Chemical Corp. )) Teflon column having an inner diameter of 15 mm and a length of 30 cm filled with 20 ml was passed at a temperature of 10 ° C. in a downward flow. At this time, there is no particular restriction on the lower part of the column, and no pressure is applied to the upper part of the column (0.3 Kg /
The liquid was applied to the liquid (cm ² or less). During the passage of the liquid, the generated bubbles remained in the refining tower and a short circuit was generated, which made it impossible to perform a stable liquid passage treatment. The total amount of organic carbon in the hydrogen peroxide solution after purification was 20 ppm.

[0014]

EFFECTS OF THE INVENTION According to the present invention, the solubility of bubbles due to the decomposition of hydrogen peroxide generated during purification can be increased, and the size of bubbles can be suppressed to be small, and the bubbles can be efficiently removed from the purification tower. Since it can be performed in a stable manner, stable liquid passage is possible, and highly purified hydrogen peroxide solution can be efficiently obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Ishiuchi 6-1, 1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Tokyo Research Laboratory

Claims (5)

[Claims] 1. A method for purifying a hydrogen peroxide solution or an aqueous solution containing hydrogen peroxide using a purifying column filled with a packing, wherein the refining is performed while applying pressure to the upper portion of the purifying column. A method for purifying an aqueous solution containing hydrogen oxide water or hydrogen peroxide. 2. The purification method according to claim 1, wherein the applied pressure is 0.5 Kg / cm ² or more. 3. The packing is an ion exchange resin.
Purification method as described. 4. The purification method according to claim 1, wherein the filling material is a chelate resin. 5. The purification method according to claim 1, wherein the filling material is an adsorption resin.