JP3812597B2 - Purification method of hydrogen peroxide - Google Patents
Purification method of hydrogen peroxide Download PDFInfo
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- JP3812597B2 JP3812597B2 JP22667695A JP22667695A JP3812597B2 JP 3812597 B2 JP3812597 B2 JP 3812597B2 JP 22667695 A JP22667695 A JP 22667695A JP 22667695 A JP22667695 A JP 22667695A JP 3812597 B2 JP3812597 B2 JP 3812597B2
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- hydrogen peroxide
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Description
【０００１】
【産業上の利用分野】
本発明は過酸化水素液中に含有する不純物を除去する過酸化水素の精製法に関する。本発明を用いて高純度に精製された過酸化水素は、特にシリコンウエハ等の半導体基板の洗浄に好適に用いられる。
【０００２】
【従来の技術】
一般に過酸化水素は蒸留法やイオン交換樹脂等によって有機及び無機不純物の除去を行い精製が行われている。一般的には蒸留法または吸着樹脂等によって有機不純物が除去され、イオン交換樹脂によって無機不純物（金属等）が除去されている。また、蒸留法によって得られた不純物含量の低い過酸化水素を吸着樹脂やイオン交換樹脂等に通液することによって、更に高純度の過酸化水素が得られている。
このようにして精製された高純度の過酸化水素はシリコンウエハ等の洗浄において塩基性もしくは酸性の過酸化水素として広く使用されており、最近の集積回路の高密度化に伴い、さらに高い精製度が要求されつつある。
【０００３】
【発明が解決しようとする問題点】
しかし、現状の精製技術では今後要求が予想されるより高純度の過酸化水素を製造するのは難しく、例えば有機不純物やコロイダルシリカ等についてはその除去が極めて困難である。これらの不純物がシリコンウエハに残留した場合の影響については現在のところまだ明確ではないが、半導体の高集積化に伴いこれらの不純物を除去する従来以上の精製技術が要望されている。
【０００４】
【問題を解決するための手段】
本発明者らは上記の問題を解決すべく鋭意検討した結果、過酸化水素に光を照射することが極めて有効であることを見いだし本発明を完成するに至った。即ち光を過酸化水素に照射することによって過酸化水素液中の有機不純物が酸化分解され炭酸ガスとなって空気中に放出されるため、過酸化水素中の有機不純物の除去が可能となる。
過酸化水素に光を照射する方法に特に制限はないが、攪拌を行い効率的に液に光を照射する方法が好ましい。また、光を照射することでオゾンが発生するが、このオゾンは自然に分解してしまうのでその後の処理で問題とはならない。ここで光を照射する過酸化水素に特に制限はなく、精製の最終段階の過酸化水素でも良く、また製造で出来た不純物濃度の高い過酸化水素でも良い。また、この時の過酸化水素の濃度に特に制限はないが好ましくは１〜７０重量％が良い。
【０００５】
また、従来、蒸留法やイオン交換樹脂による精製で除去出来なかった過酸化水素中の不純物は、光照射することによって、その後の蒸留法やイオン交換樹脂等の精製でより効率的に除去が可能となる。例えば、通常蒸留法で除去出来なかった有機不純物は、まず光照射による酸化で炭酸ガスとして空気中に放出され減少する。この時光照射での分解が不十分で炭酸ガスへとならなかった有機不純物は蟻酸、酢酸等の低分子脂肪酸として過酸化水素中に存在する。これらの低分子脂肪酸はその後蒸留法やイオン交換樹脂による精製によって容易に除去することが可能となる。同様にコロイダルシリカなどの通常イオン交換樹脂で除去が困難なコロイド状の金属も光照射によってイオン状の形態に変化し、その後イオン交換樹脂等の精製で除去する事が可能となる。
この光照射を行った後の精製に関しては特に制限はなく過酸化水素中の不純物を除去する精製法であれば良いが、特に蒸留法、イオン交換樹脂、キレート樹脂、吸着樹脂、逆浸透膜、限外濾過膜による精製が効果的である。
【０００６】
これらの精製法は組み合わせて使用することによってより高純度な過酸化水素を得ることができる。例えば、光照射を行った過酸化水素をまず蒸留法で精製し、吸着樹脂、アニオン交換樹脂、カチオン交換樹脂の順序でカラム法による通液を行うとかなり高純度の過酸化水素を得る事が出来る。この組み合わせ方、組み合わせの数に関してはより高純度の過酸化水素を得る方法であれば特に制限はない。
また、これら光照射に併せてオゾンを接触させることも有効である。このオゾンを接触させることによって光照射と同様な作用、即ち有機不純物の酸化が起こり、より効率的な精製が可能となる。
ここで、過酸化水素にオゾンを接触させる方法に関しては特に制限はないが、高濃度、高純度のオゾンガスを吹き込み攪拌等を行うのが好ましい。攪拌に関しては特に制限はないが、強攪拌によるオゾンガスとの効率的接触がより好ましい。また、超純水等に溶解させた高濃度のオゾン水を過酸化水素水の希釈に用いる方法も好ましい。これらの操作で過酸化水素中に溶解したオゾンは自然に分解してしまうため、その後の処理で問題とはならない。
【０００７】
また、この光照射に際し、遷移金属触媒を添加する方法もより好ましい。ここで遷移金属触媒としては鉄、銅、クロムが好ましい。また、これらの金属に関しては硫酸塩、硝酸塩、塩酸塩、過塩素酸塩、酸化物、水和物等の水に可溶性のものが好ましい。ここで添加する遷移金属触媒の量に関しても特に制限はないが、あまりに多量であると触媒作用として過酸化水素の分解が促進してしまい、またその後のイオン交換樹脂による除去が困難となるため可能な限り低濃度が好ましい。例えば、硝酸鉄としては０．０１〜１００ｐｐｍが好ましく、更に好ましくは０．１〜１０ｐｐｍが好ましい。
本発明の方法で用いられる光としては、紫外線が効果的である。紫外線の光源としては、太陽光、蛍光灯、キセノンランプ、ハロゲンランプ、低圧水銀ランプ高圧水銀ランプ等があり、好ましくはキセノンランプ、ハロゲンランプ、低圧水銀ランプ、高圧水銀ランプであり、更に好ましくは高圧水銀ランプ、低圧水銀ランプである。
以下にその実施例を示す。
【０００８】
【実施例】
実施例１
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１重量％の過酸化水素８００ｍｌに高圧紫外線ランプ（５００Ｗ）を照射しながら１０ｍｉｎ攪拌を行った。処理後の有機不純物濃度を測定したところ３９ｐｐｍであった。
【０００９】
実施例２
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１重量％の過酸化水素８００ｍｌに高圧紫外線ランプ（５００Ｗ）を照射しながら１０ｍｉｎ攪拌を行った。得られた過酸化水素を蒸留精製したところ、精製過酸化水素中の有機不純物は２９ｐｐｍであった。
【００１０】
実施例３
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１重量％の過酸化水素８００ｍｌに高圧紫外線ランプ（５００Ｗ）を照射しながら１０ｍｉｎ攪拌を行った。得られた過酸化水素をカチオン交換樹脂であるアンバーライトＩＲ−１２０Ｂ（Ｈ型、オルガノ（株）製）２０ｍｌを充填した内径１５ｍｍ、長さ３０ｃｍのテフロン製カラムに空間速度ＳＶ１０ｈｒ-1に通液した。次いで、アニオン交換樹脂であるアンバーライトＩＲＡ−４００（重炭酸型、オルガノ（株）製）２０ｍｌを充填した内径１５ｍｍ、長さ３０ｃｍのテフロン製カラムに空間速度ＳＶ１０ｈｒ-1に通液し、精製した。得られた精製過酸化水素中の有機不純物は、２６ｐｐｍであった。
【００１１】
実施例４
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１重量％の過酸化水素８００ｍｌに高圧紫外線ランプ（５００Ｗ）を照射しながら１０ｍｉｎ攪拌を行った。この時、２００ｍｇ／ｌのオゾンガスを０．８ｌ／ｍｉｎで吹き込んだ。得られた過酸化水素中の有機不純物は１６ｐｐｍであった。
【００１２】
実施例５
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１重量％の過酸化水素８００ｍｌに高圧紫外線ランプ（５００Ｗ）を照射しながら１０ｍｉｎ攪拌を行った。この時、金属触媒として硝酸鉄１ｐｐｍを添加した。得られた過酸化水素中の有機不純物は３４ｐｐｍであった。
【００１３】
実施例６
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１重量％の過酸化水素８００ｍｌに高圧紫外線ランプ（５００Ｗ）を照射しながら１０ｍｉｎ攪拌を行った。この時、金属触媒として塩化銅１ｐｐｍを添加した。得られた過酸化水素中の有機不純物は３５ｐｐｍであった。
【００１４】
実施例７
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１重量％の過酸化水素８００ｍｌに高圧紫外線ランプ（５００Ｗ）を照射しながら１０ｍｉｎ攪拌を行った。この時、金属触媒として硫酸クロム１ｐｐｍを添加した。得られた過酸化水素中の有機不純物は３６ｐｐｍであった。
【００１５】
比較例１
有機不純物（ＴＯＣ）として５０ｐｐｍを含む３１ｗｔ％の過酸化水素８００ｍｌを蒸留精製行った。得られた過酸化水素中の有機不純物は４４ｐｐｍであった。
【００１６】
【発明の効果】
本発明によれば、不純物を高い効率で除去することができ、特に吸着樹脂、イオン交換樹脂等で精製効率の低い有機不純物を効率よく除去することができる。本発明により得られた高純度の過酸化水素はシリコンウエハの洗浄に好適に使用し得るものである。[0001]
[Industrial application fields]
The present invention relates to a method for purifying hydrogen peroxide that removes impurities contained in a hydrogen peroxide solution. Hydrogen peroxide purified to high purity using the present invention is particularly suitable for cleaning semiconductor substrates such as silicon wafers.
[0002]
[Prior art]
In general, hydrogen peroxide is purified by removing organic and inorganic impurities by distillation or ion exchange resin. In general, organic impurities are removed by a distillation method or an adsorption resin, and inorganic impurities (metal or the like) are removed by an ion exchange resin. Further, hydrogen peroxide having a lower impurity content obtained by distillation is passed through an adsorbent resin, an ion exchange resin, or the like, so that hydrogen peroxide with higher purity is obtained.
High-purity hydrogen peroxide purified in this way is widely used as basic or acidic hydrogen peroxide in the cleaning of silicon wafers, etc., and with the recent increase in the density of integrated circuits, the higher the degree of purification. Is being demanded.
[0003]
[Problems to be solved by the invention]
However, it is difficult to produce high-purity hydrogen peroxide, which is expected to be demanded in the future with current purification techniques, and it is extremely difficult to remove, for example, organic impurities and colloidal silica. Although the effects of these impurities remaining on the silicon wafer are not yet clear at the present time, there is a demand for a more refined technology that removes these impurities as semiconductors are highly integrated.
[0004]
[Means for solving problems]
As a result of intensive studies to solve the above problems, the present inventors have found that it is extremely effective to irradiate hydrogen peroxide with light, and have completed the present invention. That is, by irradiating the hydrogen peroxide with light, the organic impurities in the hydrogen peroxide solution are oxidized and decomposed to become carbon dioxide gas and released into the air, so that the organic impurities in the hydrogen peroxide can be removed.
The method for irradiating the hydrogen peroxide with light is not particularly limited, but a method of efficiently irradiating the liquid with stirring is preferable. Moreover, although ozone is generated by irradiating light, since this ozone is naturally decomposed, there is no problem in subsequent processing. Here, the hydrogen peroxide irradiated with light is not particularly limited, and may be hydrogen peroxide at the final stage of purification, or hydrogen peroxide having a high impurity concentration produced in the production. The concentration of hydrogen peroxide at this time is not particularly limited, but preferably 1 to 70% by weight.
[0005]
In addition, impurities in hydrogen peroxide that could not be removed by purification using a distillation method or ion exchange resin in the past can be removed more efficiently by irradiation with light and subsequent purification using a distillation method or ion exchange resin. It becomes. For example, organic impurities that could not be removed by the ordinary distillation method are first released into the air as carbon dioxide gas by oxidation due to light irradiation and reduced. At this time, organic impurities which have not been decomposed by light irradiation and have not been converted to carbon dioxide exist in hydrogen peroxide as low-molecular fatty acids such as formic acid and acetic acid. These low molecular weight fatty acids can then be easily removed by distillation or purification with an ion exchange resin. Similarly, colloidal metals, such as colloidal silica, which are difficult to remove with a normal ion exchange resin, change to an ionic form upon irradiation with light, and then can be removed by purification of the ion exchange resin or the like.
There is no particular limitation on the purification after this light irradiation, and any purification method that removes impurities in hydrogen peroxide may be used. In particular, a distillation method, an ion exchange resin, a chelate resin, an adsorption resin, a reverse osmosis membrane, Purification with an ultrafiltration membrane is effective.
[0006]
These purification methods can be used in combination to obtain higher-purity hydrogen peroxide. For example, if hydrogen peroxide that has been irradiated with light is first purified by a distillation method and passed through the column method in the order of adsorption resin, anion exchange resin, and cation exchange resin, it is possible to obtain hydrogen peroxide of considerably high purity. I can do it. The method of combination and the number of combinations are not particularly limited as long as it is a method for obtaining higher-purity hydrogen peroxide.
It is also effective to bring ozone into contact with the light irradiation. By contacting this ozone, the same action as light irradiation, that is, oxidation of organic impurities occurs, and more efficient purification becomes possible.
Here, the method of bringing ozone into contact with hydrogen peroxide is not particularly limited, but it is preferable to stir and the like by blowing high concentration and high purity ozone gas. Although there is no restriction | limiting in particular regarding stirring, Efficient contact with ozone gas by strong stirring is more preferable. Also preferred is a method in which high-concentration ozone water dissolved in ultrapure water or the like is used for diluting the hydrogen peroxide solution. Since ozone dissolved in hydrogen peroxide by these operations is naturally decomposed, there is no problem in the subsequent treatment.
[0007]
In addition, a method of adding a transition metal catalyst during the light irradiation is more preferable. Here, iron, copper and chromium are preferable as the transition metal catalyst. In addition, these metals are preferably soluble in water such as sulfates, nitrates, hydrochlorides, perchlorates, oxides and hydrates. The amount of the transition metal catalyst added here is not particularly limited, but if too large, decomposition of hydrogen peroxide is promoted as a catalytic action, and subsequent removal with an ion exchange resin is difficult. A low concentration is preferable. For example, as iron nitrate, 0.01-100 ppm is preferable, More preferably, 0.1-10 ppm is preferable.
Ultraviolet rays are effective as the light used in the method of the present invention. Examples of ultraviolet light sources include sunlight, fluorescent lamps, xenon lamps, halogen lamps, low-pressure mercury lamps, and high-pressure mercury lamps, preferably xenon lamps, halogen lamps, low-pressure mercury lamps, and high-pressure mercury lamps, and more preferably high-pressure mercury lamps. Mercury lamp and low-pressure mercury lamp.
Examples are shown below.
[0008]
【Example】
Example 1
The mixture was stirred for 10 minutes while irradiating 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as organic impurities (TOC) with a high-pressure ultraviolet lamp (500 W). The organic impurity concentration after the treatment was measured and found to be 39 ppm.
[0009]
Example 2
The mixture was stirred for 10 minutes while irradiating 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as organic impurities (TOC) with a high-pressure ultraviolet lamp (500 W). When the obtained hydrogen peroxide was purified by distillation, the organic impurity in the purified hydrogen peroxide was 29 ppm.
[0010]
Example 3
The mixture was stirred for 10 minutes while irradiating 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as organic impurities (TOC) with a high-pressure ultraviolet lamp (500 W). The obtained hydrogen peroxide was passed through a Teflon column having an inner diameter of 15 mm and a length of 30 cm packed with 20 ml of Amberlite IR-120B (H type, manufactured by Organo Corp.), a cation exchange resin, at a space velocity of SV10 hr −1 . did. Next, the solution was purified by passing through a Teflon column having an inner diameter of 15 mm and a length of 30 cm packed with 20 ml of an anion exchange resin Amberlite IRA-400 (bicarbonate type, manufactured by Organo Corp.) at a space velocity of SV10 hr −1 . . The organic impurity in the obtained purified hydrogen peroxide was 26 ppm.
[0011]
Example 4
The mixture was stirred for 10 minutes while irradiating 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as organic impurities (TOC) with a high-pressure ultraviolet lamp (500 W). At this time, 200 mg / l ozone gas was blown at 0.8 l / min. The organic impurity in the obtained hydrogen peroxide was 16 ppm.
[0012]
Example 5
The mixture was stirred for 10 minutes while irradiating 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as an organic impurity (TOC) with a high-pressure ultraviolet lamp (500 W). At this time, 1 ppm of iron nitrate was added as a metal catalyst. The organic impurity in the obtained hydrogen peroxide was 34 ppm.
[0013]
Example 6
The mixture was stirred for 10 minutes while irradiating 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as an organic impurity (TOC) with a high-pressure ultraviolet lamp (500 W). At this time, 1 ppm of copper chloride was added as a metal catalyst. The organic impurity in the obtained hydrogen peroxide was 35 ppm.
[0014]
Example 7
The mixture was stirred for 10 minutes while irradiating 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as an organic impurity (TOC) with a high-pressure ultraviolet lamp (500 W). At this time, 1 ppm of chromium sulfate was added as a metal catalyst. The organic impurity in the obtained hydrogen peroxide was 36 ppm.
[0015]
Comparative Example 1
Distillation purification was performed on 800 ml of 31 wt% hydrogen peroxide containing 50 ppm as an organic impurity (TOC). The organic impurity in the obtained hydrogen peroxide was 44 ppm.
[0016]
【The invention's effect】
According to the present invention, impurities can be removed with high efficiency, and organic impurities with low purification efficiency can be efficiently removed particularly with an adsorption resin, an ion exchange resin, or the like. The high-purity hydrogen peroxide obtained by the present invention can be suitably used for cleaning silicon wafers.
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22667695A JP3812597B2 (en) | 1995-09-04 | 1995-09-04 | Purification method of hydrogen peroxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22667695A JP3812597B2 (en) | 1995-09-04 | 1995-09-04 | Purification method of hydrogen peroxide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0971405A JPH0971405A (en) | 1997-03-18 |
| JP3812597B2 true JP3812597B2 (en) | 2006-08-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22667695A Expired - Fee Related JP3812597B2 (en) | 1995-09-04 | 1995-09-04 | Purification method of hydrogen peroxide |
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| Country | Link |
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| JP (1) | JP3812597B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1520839A1 (en) * | 2003-10-02 | 2005-04-06 | SOLVAY (Société Anonyme) | Process for the purification of aqueous peroxygen solutions, solutions obtainable thereby and their use |
| JP5581090B2 (en) * | 2010-03-29 | 2014-08-27 | パナソニック株式会社 | Method and apparatus for treating waste liquid containing acid or base and hydrogen peroxide |
| CN115744832A (en) * | 2022-11-15 | 2023-03-07 | 湖南双阳高科化工有限公司 | Hydrogen peroxide purification device and purification method |
-
1995
- 1995-09-04 JP JP22667695A patent/JP3812597B2/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| JPH0971405A (en) | 1997-03-18 |
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