JPH11297657A - Washing of electronic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate metallic contamination from the surface of electronic material under easy conditions and efficiently, by bringing the washed object into contact with acid-dissolved wash water and then with oxidant-dissolved wash water. SOLUTION: A washed object is brought into contact with acid-dissolved wash water and then with oxidant-dissolved wash water. The wash water is adjusted using a reagent of high purity and superpure water. As for acid, hydrochloric acid, sulfuric acid, or nitric acid is preferably used. And, it is preferred that the pH of the acid-dissolved wash water is 4 or below, notably, 2 or below. As for the oxidant, ozone, hydrogen peroxide, sodium hypochlorite, sodium chlorite, sodium chlorate, or the like is preferably used. Among them, ozone is especially preferred because it exhibits noticeable effect even in extremely low density. The density of ozone in the wash water is preferably 0.1 mg/liter or above, notably, 1 mg/liter or above.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、電子材料の洗浄方
法に関する。さらに詳しくは、本発明は、電子材料のウ
ェット洗浄において、品質不良、歩留り低下の原因とな
る多種類の金属汚染を、電子材料表面から、温和な条件
で、同時に効率よく除去することができる電子材料の洗
浄方法に関する。The present invention relates to a method for cleaning electronic materials. More specifically, the present invention provides an electronic device capable of simultaneously and efficiently removing various types of metal contamination that causes poor quality and reduced yield from the electronic material surface under mild conditions in wet cleaning of the electronic material. The present invention relates to a method for cleaning a material.

【０００２】[0002]

【従来の技術】従来より、半導体用シリコン基板、液晶
用ガラス基板、フォトマスク用石英基板などの電子材料
表面に付着した金属不純物を除去するために、塩酸と過
酸化水素水とを混合した洗浄液を用いるいわゆるＳＣ２
洗浄や、硫酸と過酸化水素水とを混合した洗浄液を用い
るいわゆるＳＰＭ洗浄などが行われている。これらの洗
浄においては、高濃度の薬液が、１００℃前後という高
い温度で用いられている。これらの洗浄方法を採用した
場合の多大な薬液コスト、リンス用の超純水コスト、廃
液処理コスト、薬品蒸気を排気し新たに清浄空気を作る
空調コストを低減し、さらに水の大量使用、薬物の大量
廃棄、排ガスの放出などの環境への負荷を低減するため
に、近年ウェット洗浄工程の見直しが進められている。
電子材料表面に付着した金属不純物を除去するために用
いられている洗浄液の多くは、酸性かつ酸化性という性
質を有している。洗浄液の酸性かつ酸化性という性質
は、さまざまな性質を有する多種類の金属を溶解させる
上で、効果を発揮するものである。例えば、基板上の鉄
汚染物は、酸性の領域で溶解されやすく、銅汚染物は、
酸化性の領域で溶解されやすい。電子材料を汚染する可
能性のあるほとんどの金属は、酸性か酸化性の領域で溶
解させることができる。そのために、酸性かつ酸化性の
洗浄液を用いると、金属汚染物のほぼ全般を対象とする
洗浄が可能となる。これが、ＳＣ２洗浄液やＳＰＭ洗浄
液が、金属汚染一般に対し汎用性の高い洗浄液として使
用される所以である。しかし、ＳＣ２洗浄液やＳＰＭ洗
浄液には、アルカリ金属やアルカリ土類金属に対して
は、除去効果が高くないという問題点がある。一方、ウ
ェット洗浄液の省資源化、室温化が盛んに検討されるよ
うになり、非常に高い酸化力を有するオゾン水が、電子
材料の洗浄に活用されるようになった。オゾン水に酸を
添加すると、ＳＣ２洗浄液やＳＰＭ洗浄液よりさらに酸
化還元電位が高い洗浄水となる。この洗浄水は、アルカ
リ金属やアルカリ土類金属に対しても、高い洗浄効果を
発揮する。このために、酸を添加したオゾン水は、汎用
性に優れると考えられる。しかし、実際には、ニッケル
汚染や鉛汚染などのように、酸性かつ強酸化性という領
域でも比較的安定な金属が存在し、これらの金属汚染に
対しては、酸を添加したオゾン水は、良好な洗浄水とし
て機能しない。このために、アルカリ金属やアルカリ土
類金属を含むすべての金属汚染を、効果的に除去し得る
電子材料の洗浄方法が求められている。2. Description of the Related Art Conventionally, a cleaning liquid comprising a mixture of hydrochloric acid and hydrogen peroxide to remove metallic impurities adhering to the surface of electronic materials such as silicon substrates for semiconductors, glass substrates for liquid crystals, and quartz substrates for photomasks. So-called SC2 using
Cleaning and so-called SPM cleaning using a cleaning solution obtained by mixing sulfuric acid and hydrogen peroxide solution are performed. In these cleanings, a high-concentration chemical solution is used at a high temperature of about 100 ° C. The cost of chemical solutions, the cost of ultrapure water for rinsing, the cost of waste liquid treatment, the cost of air conditioning that exhausts chemical vapors and creates clean air, and the use of large amounts of water, In recent years, a review of the wet cleaning process has been promoted in order to reduce the burden on the environment such as mass disposal of waste gas and emission of exhaust gas.
Many of the cleaning liquids used for removing metal impurities attached to the surface of electronic materials have properties of being acidic and oxidizing. The acidic and oxidative properties of the cleaning solution are effective in dissolving various metals having various properties. For example, iron contaminants on the substrate are easily dissolved in acidic areas, and copper contaminants are
Easy to dissolve in oxidizing areas. Most metals that can contaminate electronic materials can be dissolved in acidic or oxidizing regions. Therefore, if an acidic and oxidizing cleaning liquid is used, it is possible to clean almost all the metal contaminants. This is the reason why the SC2 cleaning solution and the SPM cleaning solution are used as general-purpose cleaning solutions for general metal contamination. However, the SC2 cleaning solution and the SPM cleaning solution have a problem that the effect of removing alkali metals and alkaline earth metals is not high. On the other hand, resource saving and room temperature reduction of wet cleaning liquids have been actively studied, and ozone water having extremely high oxidizing power has been used for cleaning electronic materials. When an acid is added to the ozone water, the cleaning water has a higher oxidation-reduction potential than the SC2 cleaning liquid or the SPM cleaning liquid. This cleaning water exerts a high cleaning effect even on alkali metals and alkaline earth metals. For this reason, it is considered that ozone water to which an acid is added is excellent in versatility. However, in fact, there are relatively stable metals even in the acidic and strongly oxidizing regions, such as nickel contamination and lead contamination, and for these metal contaminations, ozone water added with acid Does not function as good wash water. For this reason, there is a need for a method of cleaning electronic materials that can effectively remove all metal contamination including alkali metals and alkaline earth metals.

【０００３】[0003]

【発明が解決しようとする課題】本発明は、電子材料の
ウェット洗浄において、品質不良、歩留り低下の原因と
なる多種類の金属汚染を、電子材料表面から、温和な条
件で、同時に効率よく除去することができる電子材料の
洗浄方法を提供することを目的としてなされたものであ
る。SUMMARY OF THE INVENTION According to the present invention, in wet cleaning of an electronic material, various kinds of metal contaminations which cause poor quality and reduced yield are simultaneously and efficiently removed from the surface of the electronic material under mild conditions. It is an object of the present invention to provide a method for cleaning an electronic material.

【０００４】[0004]

【課題を解決するための手段】本発明者らは、上記の課
題を解決すべく鋭意研究を重ねた結果、電子材料の表面
を汚染する金属は、酸性条件において溶解除去されやす
いもの、強酸化性条件で溶解除去されやすいもの、さら
に塩濃度の希薄な洗浄水により溶解除去されやすいもの
に大別され、従来から行われてきた酸性かつ酸化性の洗
浄液による処理に代えて、酸性洗浄水と無薬注又は薬品
濃度の希薄な強酸化性洗浄水の２種類の洗浄水と接触さ
せる２段階処理を行うことにより、洗浄不十分となって
残存する金属種がなく、多種類の金属に対して洗浄効果
が発揮されることを見いだし、この知見に基づいて本発
明を完成するに至った。すなわち、本発明は、（１）被
洗浄物を、酸を溶解した洗浄水及び酸化剤を溶解した洗
浄水と接触させることを特徴とする電子材料の洗浄方
法、を提供するものである。さらに、本発明の好ましい
態様として、（２）酸が、塩酸、硫酸又は硝酸である第
(１)項記載の電子材料の洗浄方法、（３）酸を溶解した
洗浄水のpHが、４以下である第(１)項記載の電子材料の
洗浄方法、（４）酸化剤が、オゾン、過酸化水素、塩
素、次亜塩素酸塩、亜塩素酸塩又は塩素酸塩である第
(１)項記載の電子材料の洗浄方法、（５）酸化剤を溶解
した洗浄水の標準酸化還元電位が、８００ｍＶ（対標準
水素電極）以上である第(１)項記載の電子材料の洗浄方
法、（６）被洗浄物を、酸を溶解した洗浄水と接触させ
たのち、酸化剤を溶解した洗浄水と接触させる第(１)項
記載の電子材料の洗浄方法、（７）被洗浄物を、酸化剤
を溶解した洗浄水と接触させたのち、酸を溶解した洗浄
水と接触させる第(１)項記載の電子材料の洗浄方法、
（８）酸を溶解した洗浄水との接触と、酸化剤を溶解し
た洗浄水との接触を連続的に又は一部重複させて行う第
(１)項記載の電子材料の洗浄方法、（９）酸を溶解した
洗浄水と接触させ、次いで酸及び酸化剤を溶解した洗浄
水と接触させたのち、さらに酸化剤を溶解した洗浄水と
接触させる第(１)項記載の電子材料の洗浄方法、及び、
（１０）酸化剤が、オゾンである第(６)項又は第(９)項
記載の電子材料の洗浄方法、を挙げることができる。The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, the metals contaminating the surface of the electronic material can be easily dissolved and removed under acidic conditions. It is roughly divided into those that are easily dissolved and removed under acidic conditions and those that are easily dissolved and removed by dilute washing water with a low salt concentration.Instead of the conventional treatment with an acidic and oxidizing washing solution, an acidic washing water and By performing a two-step treatment of contacting with two types of cleaning water without chemical injection or with a strong chemical oxidation diluted with chemical concentration, there is no metal species remaining due to insufficient cleaning, Thus, the present inventors have found that a cleaning effect is exhibited, and based on this finding, have completed the present invention. That is, the present invention provides (1) a method for cleaning an electronic material, which comprises contacting an object to be cleaned with cleaning water in which an acid is dissolved and cleaning water in which an oxidizing agent is dissolved. Further, as a preferred embodiment of the present invention, (2) the acid is hydrochloric acid, sulfuric acid or nitric acid.
(1) The method for cleaning an electronic material according to the item (3), (3) the method for cleaning an electronic material according to the item (1), wherein the pH of the cleaning water in which the acid is dissolved is 4 or less, and (4) the oxidizing agent is ozone. , Hydrogen peroxide, chlorine, hypochlorite, chlorite or chlorate
(1) The method for cleaning an electronic material according to (1), (5) Cleaning of the electronic material according to (1), wherein the standard oxidation-reduction potential of the cleaning water in which the oxidizing agent is dissolved is 800 mV (to a standard hydrogen electrode) or more. (6) The method for cleaning an electronic material according to (1), wherein the object to be cleaned is brought into contact with cleaning water in which an acid is dissolved, and then is contacted with cleaning water in which an oxidizing agent is dissolved; (1) The method for cleaning an electronic material according to (1), wherein the substance is brought into contact with cleaning water in which an oxidizing agent is dissolved, and then is contacted with cleaning water in which an acid is dissolved.
(8) The contact with the washing water in which the acid is dissolved and the contact with the washing water in which the oxidizing agent is dissolved are continuously or partially overlapped.
(1) The method for cleaning an electronic material according to the item (9), (9) contacting with washing water in which an acid is dissolved, and then contacting with washing water in which an acid and an oxidizing agent are dissolved; The method for cleaning an electronic material according to item (1), and
(10) The method for cleaning an electronic material according to the above item (6) or (9), wherein the oxidizing agent is ozone.

【０００５】[0005]

【発明の実施の形態】本発明の電子材料の洗浄方法にお
いては、被洗浄物を、酸を溶解した洗浄水及び酸化剤を
溶解した洗浄水と接触させる。本発明方法は、多種類の
金属により表面が汚染された電子材料の洗浄に特に好適
に適用することができる。本発明方法に用いる洗浄水
は、高純度試薬及び超純水を用いて調製することが好ま
しい。本発明方法に用いる酸には特に制限はないが、無
機酸を好適に使用することができ、塩酸、硫酸及び硝酸
を特に好適に使用することができる。これらの酸は、１
種を単独で用いることができ、あるいは２種以上を組み
合わせて用いることもできる。本発明方法において、酸
を溶解した洗浄水のpHは、４以下であることが好まし
く、２以下であることがより好ましい。酸を溶解した洗
浄水のpHが４を超えると、洗浄効果が不十分となるおそ
れがある。本発明方法に用いる酸化剤には特に制限はな
く、例えば、オゾン（Ｏ₃）、過酸化水素（Ｈ₂Ｏ₂）、
塩素（Ｃｌ₂）などの酸化性物質、次亜塩素酸ナトリウ
ム（ＮａＣｌＯ）、次亜塩素酸カルシウムなどの次亜塩
素酸塩、亜塩素酸ナトリウム（ＮａＣｌＯ₂）、亜塩素
酸カリウムなどの亜塩素酸塩、塩素酸ナトリウム（Ｎａ
ＣｌＯ₃）、塩素酸アンモニウムなどの塩素酸塩などを
挙げることができる。これらの酸化剤は、１種を単独で
用いることができ、あるいは２種以上を組み合わせて用
いることもできる。これらの中で、オゾンと過酸化水素
は、比較的取り扱いが容易であり、低濃度の溶解量で高
い洗浄効果を発揮し、洗浄後のリンスに対する負荷が小
さいので、好適に使用することができ、オゾンは、極め
て低い濃度でも顕著な効果を発揮するので、特に好適に
使用することができる。洗浄水中のオゾンの濃度は、
０.１mg／リットル以上であることが好ましく、１mg／
リットル以上であることがより好ましい。洗浄水中の過
酸化水素の濃度は、２００mg／リットル以上であること
が好ましく、１,０００mg／リットル以上であることが
より好ましい。DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of cleaning an electronic material according to the present invention, an object to be cleaned is brought into contact with cleaning water in which an acid is dissolved and cleaning water in which an oxidizing agent is dissolved. The method of the present invention can be particularly suitably applied to cleaning of an electronic material whose surface is contaminated by various kinds of metals. The washing water used in the method of the present invention is preferably prepared using a high-purity reagent and ultrapure water. The acid used in the method of the present invention is not particularly limited, but an inorganic acid can be suitably used, and hydrochloric acid, sulfuric acid and nitric acid can be particularly preferably used. These acids are 1
The species can be used alone, or two or more can be used in combination. In the method of the present invention, the pH of the washing water in which the acid is dissolved is preferably 4 or less, more preferably 2 or less. If the pH of the washing water in which the acid is dissolved exceeds 4, the washing effect may be insufficient. The oxidizing agent used in the method of the present invention is not particularly limited. For example, ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ),
Oxidizing substances such as chlorine (Cl ₂ ); sodium hypochlorite (NaClO); hypochlorites such as calcium hypochlorite; chlorine hypochlorites such as sodium chlorite (NaClO ₂ ) and potassium chlorite Acid salt, sodium chlorate (Na
Chlorates such as ClO ₃ ) and ammonium chlorate. One of these oxidizing agents can be used alone, or two or more can be used in combination. Among these, ozone and hydrogen peroxide are relatively easy to handle, exhibit a high cleaning effect with a low concentration of dissolved amount, and have a small load on rinse after cleaning, so that they can be suitably used. Since ozone exerts a remarkable effect even at an extremely low concentration, it can be used particularly preferably. The concentration of ozone in the wash water is
It is preferably at least 0.1 mg / liter,
More preferably, it is liter or more. The concentration of hydrogen peroxide in the washing water is preferably at least 200 mg / l, more preferably at least 1,000 mg / l.

【０００６】本発明方法においては、酸化剤を溶解した
洗浄水の標準酸化還元電位が８００ｍＶ（対標準水素電
極）以上であることが好ましい。洗浄水の酸化還元電位
は、溶解されている酸化剤の濃度とともに、洗浄水のpH
によっても変化する。同一pHで比較すると、酸化剤の濃
度が高いほど洗浄水の酸化還元電位は高くなり、酸化剤
の濃度が同一であると、洗浄水のpHが低いほど酸化還元
電位は高くなる。電子材料表面に付着した金属汚染を除
去する場合は、一般に洗浄水の酸化還元電位が高いほど
洗浄効果が高まるので、酸化剤の溶解量とpHの調節によ
り、所望の酸化還元電位を有する洗浄水を得ることがで
きる。本発明方法において、被洗浄物の酸を溶解した洗
浄水との接触と、酸化剤を溶解した洗浄水との接触との
順序に特に制限はなく、酸を溶解した洗浄水と接触させ
たのち、酸化剤を溶解した洗浄水と接触させることがで
き、逆に、酸化剤を溶解した洗浄水と接触させたのち、
酸を溶解した洗浄水と接触させることもでき、あるい
は、酸を溶解した洗浄水との接触と、酸化剤を溶解した
洗浄水との接触を連続的に又は一部重複させて行うこと
もできる。酸化剤がオゾンである場合には、酸を溶解し
た洗浄水と接触させたのち、酸化剤としてのオゾンを溶
解した洗浄水と接触させることが好ましい。オゾンを溶
解した洗浄水との接触を後段に行うことにより、オゾン
を溶解した洗浄水が、酸を溶解した洗浄水中の酸成分に
対するリンス水としての役割を果たす。例えば、シリコ
ン基板上に付着した硫酸成分のリンスには、オゾン水な
どの酸化性の洗浄水が、単なる超純水より効果的であ
る。洗浄水中のオゾンは、通常は１〜数mg／リットル程
度の低濃度であり、かつ電子材料表面に蒸発残渣を残す
ことがないので、オゾン水による洗浄後の超純水による
リンスを省略し、あるいは、短時間化することができ
る。このために、酸を溶解した洗浄水との接触と酸化剤
を溶解した洗浄水との接触の２段階で洗浄を行っても、
リンス工程まで含めた全体の所要時間は、従来の１段階
の洗浄方法を用いた場合とほぼ同等とすることができ
る。In the method of the present invention, the standard oxidation-reduction potential of the washing water in which the oxidizing agent is dissolved is preferably 800 mV or more (with respect to the standard hydrogen electrode). The oxidation-reduction potential of the washing water is determined by the concentration of the dissolved oxidizing agent and the pH of the washing water.
It also changes by. When compared at the same pH, the higher the concentration of the oxidizing agent, the higher the oxidation-reduction potential of the washing water. When the concentration of the oxidizing agent is the same, the lower the pH of the washing water, the higher the oxidation-reduction potential. When removing metal contamination adhering to the surface of the electronic material, generally, the higher the oxidation-reduction potential of the cleaning water, the higher the cleaning effect. Therefore, by adjusting the amount of the oxidizing agent and the pH, the cleaning water having the desired oxidation-reduction potential is adjusted. Can be obtained. In the method of the present invention, there is no particular limitation on the order of the contact of the object to be washed with the washing water in which the acid is dissolved, and the contact with the washing water in which the oxidizing agent is dissolved. , Can be brought into contact with the washing water in which the oxidizing agent is dissolved, and conversely, after contacting with the washing water in which the oxidizing agent is dissolved,
The contact with the washing water in which the acid is dissolved can be performed, or the contact with the washing water in which the acid is dissolved and the contact with the washing water in which the oxidizing agent is dissolved can be continuously or partially overlapped. . When the oxidizing agent is ozone, it is preferable that the oxidizing agent is brought into contact with washing water in which an acid is dissolved, and then is brought into contact with washing water in which ozone as an oxidizing agent is dissolved. By performing the contact with the washing water in which ozone is dissolved, the washing water in which ozone is dissolved serves as a rinse water for acid components in the washing water in which acid is dissolved. For example, rinsing of a sulfuric acid component adhered on a silicon substrate is more effective with oxidizing cleaning water such as ozone water than simple ultrapure water. Ozone in the cleaning water is usually low in concentration of about 1 to several mg / liter, and does not leave evaporation residues on the electronic material surface. Therefore, rinsing with ultrapure water after cleaning with ozone water is omitted, Alternatively, the time can be shortened. For this reason, even if washing is performed in two stages of contact with washing water in which an acid is dissolved and contact with washing water in which an oxidizing agent is dissolved,
The entire required time including the rinsing step can be made substantially equal to the case where a conventional one-step cleaning method is used.

【０００７】本発明方法においては、酸を溶解した洗浄
水と酸化剤を溶解した洗浄水を別々に用いるので、洗浄
水の循環再利用や、回収処理までを考慮すると、酸と酸
化剤の混合液よりも、酸又は酸化剤を単独に使用する洗
浄水の方が、濃度の制御や、回収などを容易に行うこと
ができる。本発明方法においては、被洗浄物を酸を溶解
した洗浄水と接触させ、次いで酸及び酸化剤を溶解した
洗浄水と接触させたのち、さらに酸化剤を溶解した洗浄
水と接触させることができる。酸化剤の濃度が同一の場
合、酸を添加してpHを下げることにより、洗浄水の酸化
還元電位が上昇し、金属汚染に対する洗浄力が強化され
る。したがって、被洗浄物を酸及び酸化剤を溶解した洗
浄水と接触させて金属汚染を除去したのち、酸化剤のみ
を溶解した洗浄水と接触させて酸成分に対するリンス効
果を及ぼすとともに、金属汚染の除去を継続することに
より、電子材料の表面の汚染を効果的に除去することが
できる。酸化剤のみを溶解した洗浄水がオゾン水である
場合は、洗浄後の超純水によるリンスを省略し、あるい
は、短時間化することができる。本発明方法において、
被洗浄物を洗浄水と接触させる方法に特に制限はなく、
例えば、洗浄水を満たした洗浄用水槽に被洗浄物を浸漬
し、被洗浄物を洗浄水と所定時間接触させるバッチ式洗
浄を行うことができ、あるいは、被洗浄物をスピンクリ
ーナーや移動架台上に載せ、洗浄水を被洗浄物の表面に
注いで処理する枚葉式洗浄を行うこともできる。バッチ
式洗浄の場合、酸を溶解した洗浄水の水槽に浸漬したの
ち、酸化剤を溶解した洗浄水の水槽に浸漬して洗浄し、
さらに超純水の水槽に浸漬してリンスすると、酸を溶解
した洗浄水の水槽から酸化剤を溶解した洗浄水の水槽に
移す中間の段階で、その両者の性質を併せ有する、酸性
かつ酸化性の洗浄水に被洗浄物を接触させることにな
り、一層万全の洗浄を行うことができる。また、スピン
クリーナーなどを用いる枚葉式洗浄においても、酸を溶
解した洗浄水から、酸化剤を溶解した洗浄水に切り替え
る中間で、酸及び酸化剤を溶解した洗浄水を使用する工
程を挿入することにより、酸性かつ酸化性の洗浄水も利
用して、一層万全の洗浄を行うことができる。[0007] In the method of the present invention, the washing water in which the acid is dissolved and the washing water in which the oxidizing agent is dissolved are separately used. Washing water using an acid or an oxidizing agent alone can more easily control the concentration and recover the liquid than the liquid. In the method of the present invention, the object to be washed can be brought into contact with washing water in which an acid is dissolved, and then contacted with washing water in which an acid and an oxidizing agent are dissolved, and further contacted with washing water in which an oxidizing agent is dissolved. . When the concentration of the oxidizing agent is the same, the oxidation-reduction potential of the washing water is increased by adding an acid to lower the pH, and the washing power against metal contamination is enhanced. Therefore, after the object to be cleaned is brought into contact with the washing water in which the acid and the oxidizing agent are dissolved to remove metal contamination, the object is brought into contact with the washing water in which only the oxidizing agent is dissolved to exert a rinsing effect on the acid component and to reduce the metal contamination. By continuing the removal, contamination on the surface of the electronic material can be effectively removed. When the cleaning water in which only the oxidizing agent is dissolved is ozone water, rinsing with ultrapure water after cleaning can be omitted or the time can be shortened. In the method of the present invention,
There is no particular limitation on the method of contacting the object to be washed with the washing water,
For example, batch cleaning can be performed by immersing the object to be cleaned in a cleaning water tank filled with cleaning water and bringing the object to be cleaned into contact with the cleaning water for a predetermined time, or the object to be cleaned can be placed on a spin cleaner or a moving platform. , And a single-wafer cleaning in which cleaning water is poured onto the surface of the object to be cleaned and treated. In the case of batch type washing, after immersing in a washing water tank in which an acid is dissolved, and then immersing in a washing water tank in which an oxidizing agent is dissolved, washing is performed.
Furthermore, when immersed in an ultrapure water bath and rinsed, it is an acidic and oxidizing agent that has the properties of both, at the intermediate stage of transferring from the washing bath containing the acid dissolved to the washing bath containing the oxidizing agent. The object to be cleaned is brought into contact with the cleaning water, so that the cleaning can be more thoroughly performed. Also, in the single-wafer cleaning using a spin cleaner or the like, a step of using cleaning water in which an acid and an oxidizing agent are dissolved is inserted in the middle of switching from cleaning water in which an acid is dissolved to cleaning water in which an oxidizing agent is dissolved. This makes it possible to perform even more thorough cleaning using the acidic and oxidizing cleaning water.

【０００８】本発明方法においては、超音波振動などの
物理的な作用を併用することができる。被洗浄物を接触
させる洗浄水に超音波振動を伝達することにより、被洗
浄物表面からの微粒子状金属汚染の除去効果を高めるこ
とができる。電子材料などの極めて微細な加工を施し、
かつ清浄な表面が求められる分野において、超音波振動
を伝達する場合には、その周波数は４００kHz以上であ
ることが好ましく、1MHz程度以上であることがより好ま
しい。超音波振動の周波数が、従来用いられている数十
kHz程度であると、超音波振動がもたらすキャビテーシ
ョン効果により、被洗浄物に損傷を与えるおそれがあ
る。本発明の洗浄方法は、通常の電子材料の汚染に対し
ては、室温においても十分な効果を発揮するが、加温す
ることによって、一層その効果を増大することができ
る。本発明の洗浄方法によれば、電子材料の表面に付着
した、マンガン、鉄、ニッケル、銀、銅、亜鉛などの金
属、ナトリウム、カリウムなどのアルカリ金属などの多
種類の金属汚染を同時に除去することができ、万能に近
い洗浄効果を得ることができる。また、洗浄水中の薬剤
濃度が低いので、洗浄コストが低く、環境に対する負荷
が小さい。In the method of the present invention, physical action such as ultrasonic vibration can be used together. By transmitting ultrasonic vibrations to the cleaning water that comes into contact with the object to be cleaned, the effect of removing particulate metal contamination from the surface of the object to be cleaned can be enhanced. Applying extremely fine processing such as electronic materials,
In the field where a clean surface is required, when transmitting ultrasonic vibration, the frequency is preferably 400 kHz or more, more preferably about 1 MHz or more. The frequency of ultrasonic vibration is
If the frequency is on the order of kHz, the object to be cleaned may be damaged due to the cavitation effect caused by the ultrasonic vibration. The cleaning method of the present invention exerts a sufficient effect on ordinary electronic material contamination even at room temperature, but the effect can be further increased by heating. According to the cleaning method of the present invention, various kinds of metal contamination such as metals such as manganese, iron, nickel, silver, copper and zinc, and alkali metals such as sodium and potassium are simultaneously removed from the surface of an electronic material. And a nearly universal cleaning effect can be obtained. Further, since the concentration of the drug in the washing water is low, the washing cost is low and the load on the environment is small.

【０００９】[0009]

【実施例】以下に、実施例を挙げて本発明をさらに詳細
に説明するが、本発明はこれらの実施例によりなんら限
定されるものではない。実施例及び比較例に用いた汚染
ウェーハは、清浄な新品のＰ(１００)タイプの６インチ
シリコンウェーハを、Ｆｅ、Ｎｉ、Ｍｎ、Ｚｎ、Ｃｕ、
Ａｇ、Ｋ及びＮａを、それぞれ１〜１０mg／リットル溶
解した水溶液に浸漬し、強制的に汚染することにより調
製した。汚染ウェーハ表面の金属濃度は、Ｆｅ２×１０
¹²個／cm ²、Ｎｉ５×１０¹¹個／cm²、Ｍｎ２×１０¹¹個
／cm²、Ｚｎ６×１０¹²個／cm²、Ｃｕ２×１０¹²個／cm
²、Ａｇ８×１０¹²個、Ｋ５×１０¹¹個／cm²、Ｎａ８×
１０¹¹個／cm²であった。なお、ウェーハ表面のＮａ濃
度は、フッ化水素蒸気分解により不純物を回収したの
ち、原子吸光分析法により測定した。Ｎａ以外の金属に
ついては、全反射蛍光Ｘ線分析装置を用いて測定した。
検出下限濃度は、Ｆｅ５×１０¹⁰個／cm²、Ｎｉ１×１
０¹⁰個／cm²、Ｍｎ１×１０¹⁰個／cm²、Ｚｎ１×１０¹⁰
個／cm²、Ｃｕ５×１０¹⁰個／cm²、Ａｇ３×１０¹¹個、
Ｋ２×１０¹¹個／cm²、Ｎａ１×１０ ¹⁰個／cm²である。 実施例１ 浸漬法により、汚染ウェーハの洗浄を行った。汚染ウェ
ーハを、超純水に塩酸を添加してpH１に調整した洗浄水
に１０分間浸漬し、次いで超純水にオゾン２mg／リット
ルを溶解したpH７の洗浄水に１０分間浸漬して洗浄し、
最後に超純水に１分間浸漬してリンスした。洗浄後のウ
ェーハの表面には、いずれの金属も検出されなかった。 実施例２ 枚葉式スピン洗浄装置を用いて、汚染ウェーハの洗浄を
行った。洗浄水の流量は８００ml／分、ウェーハの回転
速度は５００rpmとした。超純水に塩酸を添加してpH１
に調整した洗浄水を用いて３０秒間、次いで超純水にオ
ゾン２mg／リットルを溶解し、塩酸を添加してpH１に調
整した洗浄水を用いて１０秒間、さらに超純水にオゾン
２mg／リットルを溶解したpH７の洗浄水を用いて２０秒
間洗浄し、最後に超純水を用いて５秒間リンスした。洗
浄後のウェーハの表面には、いずれの金属も検出されな
かった。 比較例１ ＳＣ２法により、汚染ウェーハの洗浄を行った。汚染ウ
ェーハを、３５重量％塩酸、３０重量％過酸化水素水及
び超純水の容量比１：１：６の混合液からなる洗浄液に
１０分間浸漬して洗浄し、次いで超純水に１０分間浸漬
してリンスした。洗浄後のウェーハの表面の金属濃度
は、Ｋ３×１０¹¹個／cm²、Ｎａ５×１０^{1 0}個／cm²であ
り、ＫとＮａ以外の金属は検出されなかった。 比較例２ ＳＰＭ法により、汚染ウェーハの洗浄を行った。汚染ウ
ェーハを、９８重量％硫酸と３０重量％過酸化水素水の
容量比４：１の混合液からなる洗浄液に１０分間浸漬し
て洗浄し、次いで超純水に１０分間浸漬してリンスし
た。洗浄後のウェーハの表面の金属濃度は、Ｋ３×１０
¹¹個／cm²、Ｎａ７×１０^{1 0}個／cm²であり、ＫとＮａ以
外の金属は検出されなかった。 比較例３ オゾン水に浸漬することにより、汚染ウェーハの洗浄を
行った。汚染ウェーハを、超純水にオゾン２mg／リット
ルを溶解したpH７の洗浄水に１０分間浸漬して洗浄し、
次いで超純水に１０分間浸漬してリンスした。洗浄後の
ウェーハの表面の金属濃度は、Ｆｅ１×１０¹²個／c
m²、Ｎｉ５×１０¹⁰個／cm²、Ｍｎ３×１０¹⁰個／cm²、
Ｚｎ４×１０¹⁰個であり、Ｃｕ、Ａｇ、Ｋ及びＮａは検
出されなかった。 比較例４ 塩酸を添加したオゾン水に浸漬することにより、汚染ウ
ェーハの洗浄を行った。汚染ウェーハを、超純水にオゾ
ン２mg／リットルを溶解し、塩酸を添加してpH１に調整
した洗浄水に１０分間浸漬して洗浄し、次いで超純水に
１０分間浸漬してリンスした。洗浄後のウェーハの表面
の金属濃度は、Ｆｅ６×１０¹¹個／cm²、Ｍｎ１×１０
¹⁰個／cm²であり、ＦｅとＭｎ以外の金属は検出されな
かった。実施例１〜２及び比較例１〜４の洗浄条件を第
１表に、洗浄結果を第２表に示す。The present invention will be described in more detail with reference to the following examples.
The present invention is not limited to these examples.
It is not specified. Contamination used in Examples and Comparative Examples
The wafer is a clean new P (100) type 6 inch
Silicon wafers are made of Fe, Ni, Mn, Zn, Cu,
Ag, K and Na are each dissolved at 1 to 10 mg / liter.
Immersed in an aqueous solution that has been
Made. The metal concentration on the surface of the contaminated wafer is Fe2 × 10
¹²Pieces / cm ^Two, Ni5 × 10¹¹Pieces / cm^Two, Mn2 × 10¹¹Individual
/cm^Two, Zn6 × 10¹²Pieces / cm^Two, Cu2 × 10¹²Pieces / cm
^Two, Ag8 × 10¹²Pcs, K5 × 10¹¹Pieces / cm^Two, Na8 ×
10¹¹Pieces / cm^TwoMet. The Na concentration on the wafer surface
As for the degree, impurities were recovered by decomposition of hydrogen fluoride vapor.
Then, it was measured by atomic absorption spectrometry. For metals other than Na
This was measured using a total reflection X-ray fluorescence analyzer.
The lower detection limit concentration is Fe5 × 10^TenPieces / cm^Two, Ni1 × 1
0^TenPieces / cm^Two, Mn 1 × 10^TenPieces / cm^Two, Zn1 × 10^Ten
Pieces / cm^Two, Cu5 × 10^TenPieces / cm^Two, Ag3 × 10¹¹Individual,
K2 × 10¹¹Pieces / cm^Two, Na1 × 10 ^TenPieces / cm^TwoIt is. Example 1 A contaminated wafer was cleaned by an immersion method. Pollution
Washing water adjusted to pH 1 by adding hydrochloric acid to ultrapure water
For 10 minutes, then 2mg / lit of ozone in ultrapure water
Immersed in washing water of pH 7 in which
Finally, it was rinsed by immersing it in ultrapure water for 1 minute. After cleaning
No metal was detected on the wafer surface. Example 2 Cleaning of contaminated wafers using a single-wafer spin cleaning apparatus
went. Cleaning water flow rate 800ml / min, wafer rotation
The speed was 500 rpm. Add hydrochloric acid to ultrapure water to pH1
For 30 seconds using the adjusted washing water, and then to ultrapure water.
Dissolve 2 mg / l of zon and adjust to pH 1 by adding hydrochloric acid
Ozone was added to ultrapure water for 10 seconds using the adjusted cleaning water.
20 seconds using pH 7 washing water in which 2 mg / liter is dissolved
Then, the substrate was rinsed with ultrapure water for 5 seconds. Washing
No metal is detected on the cleaned wafer surface.
won. Comparative Example 1 A contaminated wafer was cleaned by the SC2 method. Pollution
The wafer is treated with 35% by weight hydrochloric acid, 30% by weight hydrogen peroxide solution and
Cleaning solution consisting of a mixture of water and ultrapure water in a volume ratio of 1: 1: 6
Wash by immersing for 10 minutes, then immerse in ultrapure water for 10 minutes
And rinsed. Metal concentration on wafer surface after cleaning
Is K3 × 10¹¹Pieces / cm^Two, Na5 × 10^{1 0}Pieces / cm^TwoIn
No metals other than K and Na were detected. Comparative Example 2 A contaminated wafer was cleaned by the SPM method. Pollution
The wafer is mixed with 98% by weight sulfuric acid and 30% by weight hydrogen peroxide solution.
Immersed in a cleaning solution consisting of a mixed solution having a volume ratio of 4: 1 for 10 minutes
Rinsing by immersion in ultrapure water for 10 minutes
Was. The metal concentration on the surface of the wafer after cleaning is K3 × 10
¹¹Pieces / cm^Two, Na7 × 10^{1 0}Pieces / cm^TwoAnd K and Na
No extraneous metal was detected. Comparative Example 3 Cleaning of contaminated wafers by immersion in ozone water
went. Contaminated wafers in ultrapure water with ozone 2mg / lit
Immersed in washing water of pH 7 in which
Then, it was rinsed by immersing it in ultrapure water for 10 minutes. After washing
The metal concentration on the surface of the wafer is Fe1 × 10¹²Pcs / c
m^Two, Ni5 × 10^TenPieces / cm^Two, Mn 3 × 10^TenPieces / cm^Two,
Zn4 × 10^TenAnd Cu, Ag, K and Na were detected.
I was not issued. Comparative Example 4 By immersing in ozone water to which hydrochloric acid was added,
The wafer was cleaned. Contaminated wafers in ultrapure water
Dissolve 2mg / l, add hydrochloric acid and adjust to pH1
Immersed in the washing water for 10 minutes to wash, and then
Rinse by soaking for 10 minutes. Wafer surface after cleaning
The metal concentration of Fe6 × 10¹¹Pieces / cm^Two, Mn 1 × 10
^TenPieces / cm^TwoAnd metals other than Fe and Mn were not detected.
won. The cleaning conditions of Examples 1-2 and Comparative Examples 1-4 were
Table 1 shows the cleaning results in Table 2.

【００１０】[0010]

【表１】 [Table 1]

【００１１】[0011]

【表２】 [Table 2]

【００１２】第１表に見られるように、塩酸を溶解した
洗浄水とオゾンを溶解した洗浄水を用いて２段階の浸漬
洗浄を行った実施例１、及び、塩酸を溶解した洗浄水と
オゾンを溶解し塩酸を添加した洗浄水とオゾンを溶解し
た洗浄水を用いて３段階のスピン洗浄を行った実施例２
においては、Ｆｅ、Ｎｉ、Ｍｎ、Ｚｎ、Ｃｕ、Ａｇ、Ｋ
及びＮａのすべての金属が、ウェーハ表面より検出下限
値以下まで除去されている。これに対して、塩酸過酸化
水素水（ＳＣ２）を用いた比較例１及び硫酸過酸化水素
水（ＳＰＭ）を用いた比較例２においては、ＫとＮａの
除去が不十分で検出下限値以上に残存する。また、オゾ
ン水を用いた比較例３においては、Ｆｅ、Ｎｉ、Ｍｎ及
びＺｎの除去が不十分で検出下限値以上に残存し、オゾ
ン水に塩酸を添加した洗浄水を用いた比較例４において
も、なおＦｅとＭｎが検出下限値以上に残存する。洗浄
とリンスに要する所要時間の合計は、洗浄を２段階に行
った実施例１も、洗浄を１段階に行った比較例１〜４と
同等である。これらの結果から、被洗浄物を、酸を溶解
した洗浄水及び酸化剤を溶解した洗浄水と接触させる本
発明の電子材料の洗浄方法は、低濃度の洗浄水を用いて
も所要時間が長引くことがなく、多種類の金属汚染を同
時に効果的に除去することができる汎用性の高い洗浄方
法であることが分かる。As can be seen from Table 1, two-stage immersion cleaning was carried out using cleaning water in which hydrochloric acid was dissolved and cleaning water in which ozone was dissolved, and cleaning water in which hydrochloric acid was dissolved and ozone. Example 2 in which three-stage spin cleaning was performed using cleaning water in which hydrochloric acid was added and hydrochloric acid was added, and cleaning water in which ozone was dissolved.
, Fe, Ni, Mn, Zn, Cu, Ag, K
And all metals of Na have been removed from the wafer surface to the detection lower limit or less. On the other hand, in Comparative Example 1 using hydrochloric acid hydrogen peroxide solution (SC2) and Comparative Example 2 using sulfuric acid hydrogen peroxide solution (SPM), the removal of K and Na was insufficient and the detection limit was exceeded. To remain. In Comparative Example 3 using ozone water, the removal of Fe, Ni, Mn and Zn was insufficient and remained at or above the lower detection limit, and in Comparative Example 4 using cleaning water obtained by adding hydrochloric acid to ozone water. Also, Fe and Mn remain above the lower detection limit. The total time required for cleaning and rinsing is the same as in Example 1 in which cleaning was performed in two stages, and in Comparative Examples 1 to 4 in which cleaning was performed in one stage. From these results, in the method for cleaning an electronic material of the present invention in which an object to be cleaned is brought into contact with cleaning water in which an acid is dissolved and cleaning water in which an oxidizing agent is dissolved, the required time is prolonged even when low-concentration cleaning water is used. It can be seen that this is a highly versatile cleaning method capable of simultaneously and effectively removing various types of metal contamination.

【００１３】[0013]

【発明の効果】本発明の電子材料の洗浄方法によれば、
従来法に比べてより汎用性が高く、多種類の金属を同時
に除去することが可能となる。本発明方法においては、
酸及び酸化剤の濃度の低い洗浄水を別々に用いるので、
洗浄水の濃度制御及び薬液の回収処理が容易になる。ま
た、洗浄に要する時間は、従来法と同等レベルである。According to the method for cleaning an electronic material of the present invention,
The versatility is higher than the conventional method, and it is possible to remove many kinds of metals at the same time. In the method of the present invention,
Since wash water with low concentrations of acid and oxidant is used separately,
Control of the concentration of the cleaning water and recovery of the chemical solution are facilitated. Also, the time required for cleaning is at the same level as the conventional method.

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】被洗浄物を、酸を溶解した洗浄水及び酸化
剤を溶解した洗浄水と接触させることを特徴とする電子
材料の洗浄方法。1. A method of cleaning an electronic material, comprising contacting an object to be cleaned with cleaning water in which an acid is dissolved and cleaning water in which an oxidizing agent is dissolved.