JP2004089971A

JP2004089971A - Heating treatment method of ozone water

Info

Publication number: JP2004089971A
Application number: JP2002291663A
Authority: JP
Inventors: Yoichi Shimoi; 下井　洋一; Takio Adachi; 安達　太起夫; Toshio Tayadate; 田屋舘　利夫; Teruo Shinbara; 榛原　照男; Kenichi Kamimura; 上村　賢一
Original assignee: Nittetsu Chemical Engineering Co Ltd; Wacker NSCE Corp; Nittetsu Kakoki KK
Current assignee: Siltronic Japan Corp; Tsukishima Kankyo Engineering Ltd; Nippon Steel Eco Tech Corp
Priority date: 2002-08-29
Filing date: 2002-08-29
Publication date: 2004-03-25
Anticipated expiration: 2022-08-29
Also published as: JP4444557B2

Abstract

<P>PROBLEM TO BE SOLVED: To improve the safety of a treating operation and reduce the load of rinse and wastewater disposal as compared with conventional condensation and high-temperature chemical liquid treatments by providing a method for effectively super-heating high concentration ozone water by charging less energy to utilize the treatment of a substrate or the like. <P>SOLUTION: In the method that the surface of an object to be treated is treated or cleaned by supplying ozone onto the material. The heating method for ozone water is characterized by using the heated ozone water mixed with steam immediately before supplying the ozone water. The ozone water can be loaded with an acid. an alkali and an inhibitor for decomposing ozone. A substrate or the like is efficiently treated by utilizing the increased oxidation power of ozone by heating. The rinse and wastewater disposal is facilitated compared with the treatment by the conventional plasma ashing and the mixture of sulfuric acid with hydrogen peroxide. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、オゾン水を用いて被処理対象物の洗浄を含めた表面処理を行う場合のオゾン水の加熱に係わるものである。詳しくは、半導体の製造工程にて行われる基板等のレジスト剥離や洗浄操作において利用されるオゾン水を用いた基板等の処理や、一般の樹脂等の表面処理や金属等の洗浄や表面処理にオゾン水を利用する場合に用いられる方法である。より詳しくは、半導体基板や液晶基板処理においては、レジスト層や有機性の汚染の除去、汚染金属や異物の除去、半導体や液晶製造に用いられている石英板等からなるマスク材における有機性／無機性の汚染または異物の除去等に適用できるオゾン水を用いた基板等の処理方法であり、樹脂や金属の処理においては、樹脂の表面酸化処理、金属表面の有機物除去や洗浄、酸化処理を挙げることができる。
【０００２】
【従来の技術】
半導体基板や液晶基板製造時に基板上に形成されるレジストの剥離には、これまでプラズマを用いたアッシングや硫酸と過酸化水素の混合液（以下硫酸過水と略称する）が用いられている。しかし、これら従来の処理方法は、処理の均一性や多量のリンス水の必要性、処理工程からの廃水処理の問題等から、近年新たにオゾン水を用いた処理法の開発が活発になってきた。また、これらと同様にマスク材である石英板の洗浄も硫酸過水からオゾン水への転換が図られている。これらの処理を効果的に行うためにより高濃度のオゾン水を使用したり、オゾン水に超音波や紫外線（ＵＶ）照射等を併用する方法が開発されている。
【０００３】
従来のオゾン水製造設備では、超高濃度といわれる水中のオゾン濃度１００ｐｐｍを達成するために２〜５℃以下の低温とすることが必要であり、オゾン濃度は高いものの活性が不十分となる状況であった。このため、基板の処理を洗浄浴の中で行う浸漬型の場合には、オゾン水をヒータ等の加熱源を利用して加熱したり（特開２０００−５８４９６号公報、特開２０００−３０１０８５号公報他）、回転テーブル上に固定した基板にオゾン水を流下する枚葉型の場合には、該テーブルあるいはテーブル近傍からの加熱源により基板を加熱したり、基板に流下したオゾン水を加熱して処理する方法（特開２００１−７７０６９号公報、特開２００１−１５６０４９号公報）等が提案されている。
【０００４】
しかしながら、前記の特開２０００−５８４９６号公報、特開２０００−３０１０８５号公報では、オゾン水の加熱にヒーター等の熱源を利用しているため、いわば間接熱交換器に相当する状態での伝熱のために加熱に時間を要し、オゾン水が加熱された結果自己分解速度が急激に増大し、特に高濃度オゾン水を使用する場合昇温の間にオゾン水濃度が低下するおそれがある。また、浸積型では、オゾン水の滞留時間のために高温下での自己分解によるオゾンの濃度低下が大きく、高濃度オゾン水の強酸化特性が十分には利用できなくなる。
【０００５】
一方の特開２００１−７７０６９号公報、特開２００１−１５６０４９号公報では、枚葉型ではあるが、基板を加熱する場合には、オゾン水の熱容量が約１．０ｃａｌ／ｇ・ｄｅｇに対し、基板の熱容量が０．１７ｃａｌ／ｇ・ｄｅｇであるため、加熱した基板に単にオゾン水を接触させるだけでは熱量的にオゾン水の十分な加熱は困難であり、基板を常時下部あるいは上方から加熱することが必要となる。
また、基板を支えるテーブルは、通常フッ素樹脂で製作されており、回転テーブル等に固定された基板上を高速に流れるオゾン水を急速に加熱するため、それに要する有効な伝熱速度を得るためには過大な熱量が必要になる。基板上に流下したオゾン水に水蒸気を吹きかけて昇温する方法では、基板の半径方向にオゾン水の温度分布が生じ処理速度にむらが発生するおそれがある。
【０００６】
【発明が解決しようとする課題】
本発明は、高濃度オゾン水を少ないエネルギー投入量で効果的に加熱する方法を提供し、基板等の処理に利用することにより、上記のような従来の高温オゾン水利用上における問題点の改善を図るものである。また、従来の硫酸過水のような濃厚かつ高温度の過酷な条件での薬液処理に比べて、処理作業の安全性を改善し、リンス負荷の軽減、廃水処理負荷の軽減等が見込める技術を提供しようとするものである。
【０００７】
【課題を解決するための手段】
本発明は、基板等の被処理対象物上にオゾン水を供給して基板等の表面を処理または洗浄する処理方法において、オゾン水を供給する直前に蒸気を混合しオゾン水を加熱して使用することを特徴とするオゾン水を用いた被処理対象物の処理方法である。
すなわち、水中のオゾンが非常に早く分解してしまう特性を持つことから、オゾン水の加熱にヒータのような間接的な方法を用いるのではなく、オゾン水を被処理物に適用する直前に蒸気を混合し、蒸気の凝縮熱を直接利用してオゾン水を急速に加熱し利用する方法である。
【０００８】
本発明における被処理対象物としては、オゾン水の有する強酸化特性を利用して処理を行う多くの材料が用いられる。特にこの要求の高い半導体関連材料としては、半導体材料基板であるウェハーや、マスク材である石英板等を挙げることができる。これらの材料は、半導体製造過程において、原材料ウェハー洗浄、レジスト塗布、エッチング、元素ドーピング、レジスト剥離、洗浄等の様々な処理が行われるが、レジスト剥離や原材料ウェハー洗浄を含めた種々の洗浄にオゾン水の利用が進み、そのための開発が行われ、実用化も進展している。
【０００９】
オゾン水と蒸気の混合は、オゾン水の供給ラインに直接蒸気を流入させるかあるいは混合器を設け混合する方法であることが望ましい。また、オゾン水の供給ラインにおけるオゾン水の流速を利用して蒸気を吸引し、オゾン水と蒸気の混合を行うことも好ましい方法の一つである。
【００１０】
本発明において用いる蒸気としては、有機溶剤蒸気や有機溶剤を含有した水蒸気、塩化水素やアンモニアに代表される酸やアルカリを含有した水蒸気、水蒸気等使用目的に応じ種々の蒸気を選択することができる。この中でも水蒸気の利用が、凝縮熱が大きく、取扱いの容易さや経済性等から望ましいものである。また、半導体材料の処理に水蒸気を用いる場合は、基板等の汚染を防止するために、純水や超純水の使用が望ましい。
【００１１】
一方オゾン水についても使用目的に応じ、例えば洗浄や溶解操作においてよく利用されるように、酸やアルカリを含有するオゾン水を用いることができる。
また、水中のオゾンの分解を抑制するためにオゾン水に、酸、二酸化炭素、有機物などのオゾンの分解抑止剤を添加することもよく行われる。常温ではこれらの抑止剤の効果が働きオゾンの自己分解速度が低下する。しかし、これらのオゾン水を加熱し高温にする場合、一般の化学反応特性から予測できるように高温ではオゾンの分解速度が上昇し、これらの系においても被処理物へ供給する直前に蒸気を直接混合し急速加熱を行うことがオゾンの酸化力を有効に利用するために効果的な方法になる。これらの詳細は後述する。
【００１２】
オゾン水の濃度としては、特に規定するものではないが、オゾンの自己分解が活発になるオゾン水濃度２０ｐｐｍ以上に対して本発明の方法の適用がより効果的である。
【００１３】
【発明の実施の形態、作用】
本発明者らは、充填塔を用いてオゾン水を製造する際に、逆混合を防止して効率的に高濃度のオゾン水を製造する方法を開発し、先にこの考え方に基づくオゾン水製造設備について特許出願（特開２０００−１６７３６６号公報）を行った。
その後本発明者らは、前記のオゾン水製造設備を用いて常温で１００ｐｐｍを越える超高濃度オゾン水の製造に成功し、この超高濃度オゾン水を用いて自己分解速度や基板上の有機物の除去特性等を検討した結果、超純水中での超高濃度オゾン水の常温での分解速度は、半減期が数秒以下の非常に早い自己分解特性を持つこと、基板上の有機物の除去特性は温度に大きく依存することが判明した。
【００１４】
このことにより、基板等を効果的にオゾン水処理するためには、高温での処理が好ましいこと、オゾン水の昇温は時間をかけずに瞬時に達成しなければならないこと、浸漬型のようにオゾン水の滞留時間がある程度必要な処理では、特に高温の場合、オゾンの自己分解のために超高濃度オゾン水の強い酸化分解特性を十分には生かすことができないこと等が重要な要因として明らかになった。
【００１５】
本発明者らは、上記の結果を考慮し、枚葉型の基板処理や一般材料の表面処理に対しオゾン水を急速に加熱する方法を開発し、本発明のオゾン水に蒸気を直接混合し加熱して使用する方法を完成した。
【００１６】
以下、本発明の実施の形態および作用を、特開２０００−１６７３６６号公報に開示されている設備で製造したオゾン水を利用した例で説明するが、本発明はオゾン水の製造方法によらず実施可能であり、本発明を限定するものではない。
【００１７】
蒸気としては単純な水蒸気以外も有効であるが、代表として水蒸気を例に取ると、１００℃の水蒸気は６３９．１５ｋｃａｌ／ｋｇのエンタルピーを持ち、８０℃の水は７９．９９３ｋｃａｌ／ｋｇのエンタルピーを持つので、２０℃の水（エンタルピー２０．０３０ｋｃａｌ／ｋｇ）を８０℃まで昇温するためには０．１０７ｋｇ／ｋｇ量の水蒸気を添加するだけでよく、水蒸気から水への熱の移動は大部分が凝縮熱（蒸発潜熱）によるので瞬時であり、蒸気の持つエネルギーのほぼ全量を利用できる。
【００１８】
また、水に対する蒸気重量は１／１０程度であるので、水蒸気を添加することで希釈されるオゾン濃度の減少は１割程度でしかなく、水蒸気は純水や超純水から製造することができるので汚染（コンタミネーション）の少ない均一な加熱オゾン水を作ることができる。加熱温度としては、加圧下ではより高い温度も可能であるが、常圧の場合、反応速度の上昇と取り扱い易さを考慮して５０〜９５℃、好ましくは６０〜９０℃程度が適切である。
【００１９】
この加熱オゾン水は結果として過飽和のオゾンを含有するオゾン水になるが、水蒸気との混合を基板等へ流下する直前で行い、２〜１０ｍ／ｓ程度の流速で基板へ噴出することで自己分解や気相への放散をできるだけ抑えて基板等の処理に利用することができる。
【００２０】
オゾン水による強酸化力をより効果的に利用するために加熱を行ったが、オゾン水濃度も処理速度を上昇させるために重要であり、オゾン水の製造に請求項４に示した設備を用いて得られる高濃度のオゾン水を使用することがより効果的である。すなわち、特開２０００−１６７３６６号公報に詳細な内容が開示されているように、充填塔の上部に水の導入口と排ガスの出口、該充填塔の下部にオゾンガスの導入口とオゾン水の取り出し口を備え、その間にガス逆流防止板で仕切られた充填層を二つ以上設け、水とオゾンガスとを向流接触させる充填塔方式のオゾン水製造設備によりオゾン水を製造することで、高濃度のオゾン水を効率よく入手できる。
【００２１】
基板等の洗浄のために、使用するオゾン水に酸を添加することは洗浄能力の増大、オゾンの自己分解抑制に有効であり、酸としては、フッ酸、塩酸、硝酸、硫酸、燐酸、有機酸（例えば蟻酸、酢酸、クエン酸など）から選択し、適宜目的に応じて添加できる。
【００２２】
また、オゾン水におけるオゾンの自己分解抑制のために、自己分解抑止剤を予め添加しておくこともよく行われる。オゾン水の自己分解抑止剤としては、酸、二酸化炭素（ＣＯ_２）や有機物の添加が有効であり、酸としては塩酸、硝酸、酢酸、蟻酸等であり、有機物としてはイソプロピルアルコール、アセトン、メチルアルコール、エチルアルコール等をその例として挙げられる。これらのいずれか一種以上を用いることができ、単独でもこれらを併用してもよい。これらの自己分解抑止剤を添加することで、常温でのオゾンの自己分解速度はかなり減少し、本発明のように加熱した場合であっても有効である。
【００２３】
次に、本発明を実施するための装置について、図面を基に詳述する。図１は、本発明を実施するための装置の一例で、その概念図を示すものである。
図１のテーブル５上に基板４を固定し、オゾン水と水蒸気を混合器１で混合し瞬間的に加熱して、直ちにノズル２から基板４に対して噴出する機構となっている。
オゾン水と水蒸気の混合を行う方法については、できるだけ短時間に均一な混合を行うことができればよく、オゾン水の供給ラインに直接水蒸気を流入させるかあるいは混合器を設け混合する方法等が例示できる。
図１では噴霧ノズルの形式の混合器を説明したが、混合器１は単にオゾン水ラインに水蒸気を流入させる形式のものでもよい。また、高濃度オゾン水を製造するためにオゾン水は加圧されることが多く、加圧されたオゾン水をそのまま使用すると、ノズルから高速で噴出するので、オゾン水と水蒸気の混合部分を例えばアスピレータのように高速のオゾン水流を利用して水蒸気を吸引する形式のものとしてもよい。
また、実験は静止したノズル１本で行ったが、実用的には適用目的に応じノズルを移動したり、複数本のノズルで行うようにすることも可能である。
【００２４】
【実施例１】
図１に示した装置を用いて、基板上にレジストを１μｍ形成しリン（Ｐ）を１×１０^１４ｉｏｎｓ／ｃｍ^２インプラントしたレジストの剥離試験を行った。レジストの剥離速度は、加熱オゾン水を所定時間流下したときの処理前後のレジスト膜厚を測定し算出した。試験では図示していないカバーに覆われた図１の装置のテーブル５上に基板４をセットした後、オゾン水と水蒸気を混合器１で混合し瞬間的に加熱し、直ちにノズル２から基板４上に噴出させた。処理温度は、あらかじめ、基板を設置しない状況でノズルから基板までの距離に相当する位置に温度計を置きオゾン水の所定流量に対する目的温度まで加熱するのに必要な蒸気量を求めておき、同流量の蒸気を流すことで設定した。濃度１００ｐｐｍのオゾン水によるレジスト剥離試験の結果を表１に示した。
【００２５】

【００２６】
水蒸気添加により最大１割程度オゾン水中のオゾン濃度が低下しているにもかかわらず、加熱により格段の剥離除去効果が得られている。また、この実施例から、水蒸気による急速加熱により有効なオゾンが損なわれることなくオゾン処理の効果が得られることが判る。
【００２７】
上記実施例では、テーブルおよび基板は静止したままで試験を行ったが、テーブルを回転させることで、基板表面でのより早いオゾン水の更新が起こり、よりよい効果が期待できる。
【００２８】
【実施例２】
実施例１と同様の設備及び方法により、蒸気による加熱オゾン水温度を８０℃として供給するオゾン水濃度を変えて実験を行った。使用した試料は実施例１と同様に基板上のレジスト（１μｍ）にリンを１×１０^１４ｉｏｎｓ／ｃｍ^２インプラントした試料である。得られた結果を表２に示した。
【００２９】

【００３０】
比較例である単に８０℃の温水ではレジストの剥離に効果はなく、加熱したオゾン水がレジストの剥離に有効であった。オゾン濃度の増大と共に直線的に剥離速度が増大している。
【００３１】
【発明の効果】
本発明によれば、加熱により増大したオゾンの酸化力を利用して、基板やマスク材等の表面を効果的に処理することが可能となる。本発明の方法は、従来のプラズマアッシングや硫酸過水のような不均一であったり過剰なエネルギーを消費する方法や、多量のリンス水を必要としたり廃水処理に多大なコストがかかる方法に代わる新しい処理法であり、従来の常温のオゾン水と比較して処理時間の大幅な短縮が期待でき、裨益するところ大である。
【図面の簡単な説明】
【図１】本発明を実施するための装置の概念図の一例である。
【符号の説明】
１　　混合器
２　　噴出ノズル
３　　加熱オゾン水
４　　被処理基板
５　　テーブル[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to heating of ozone water when performing surface treatment including cleaning of an object to be processed using ozone water. Specifically, it is used for processing of substrates and the like using ozone water used in resist stripping and cleaning operations of substrates and the like performed in semiconductor manufacturing processes, surface treatment of general resins and the like, and cleaning and surface treatment of metals and the like. This method is used when using ozone water. More specifically, in the processing of semiconductor substrates and liquid crystal substrates, removal of resist layers and organic contaminants, removal of contaminant metals and foreign substances, and organic / This is a method for treating substrates and the like using ozone water that can be applied to the removal of inorganic contamination or foreign substances.In the treatment of resins and metals, the surface oxidation treatment of the resin, the removal of organic substances on the metal surface, washing, and oxidation treatment Can be mentioned.
[0002]
[Prior art]
Ashing using plasma or a mixed solution of sulfuric acid and hydrogen peroxide (hereinafter abbreviated as sulfuric acid / hydrogen peroxide) has been used for stripping a resist formed on a substrate when a semiconductor substrate or a liquid crystal substrate is manufactured. However, in these conventional treatment methods, the development of a treatment method using ozone water has recently become active due to the uniformity of treatment, the need for a large amount of rinsing water, and the problem of treatment of wastewater from the treatment step. Was. Similarly, in cleaning the quartz plate as a mask material, conversion from sulfuric acid peroxide to ozone water is also attempted. In order to effectively perform these treatments, a method of using a higher concentration of ozone water or a method of using ultrasonic waves or ultraviolet (UV) irradiation together with the ozone water has been developed.
[0003]
Conventional ozone water production equipment requires a low temperature of 2 to 5 ° C or less to achieve an ozone concentration of 100 ppm in water, which is said to be an ultra-high concentration, and the ozone concentration is high but the activity is insufficient. Met. For this reason, in the case of the immersion type in which the processing of the substrate is performed in a cleaning bath, the ozone water is heated by using a heating source such as a heater (Japanese Patent Application Laid-Open Nos. 2000-58496 and 2000-31085). In the case of a single-wafer type in which ozone water flows down onto a substrate fixed on a rotary table, the substrate is heated by a heating source from the table or from the vicinity of the table, or ozone water flowing down to the substrate is heated. (For example, JP-A-2001-77069 and JP-A-2001-156049).
[0004]
However, in the above-mentioned JP-A-2000-58496 and JP-A-2000-301085, since a heat source such as a heater is used for heating ozone water, heat transfer in a state corresponding to an indirect heat exchanger can be described. For this reason, heating requires a long time, and the self-decomposition rate sharply increases as a result of heating the ozone water. Particularly, when high-concentration ozone water is used, the ozone water concentration may decrease during the temperature rise. In addition, in the immersion type, the concentration of ozone is greatly reduced due to self-decomposition at a high temperature due to the residence time of the ozone water, and the strong oxidation characteristics of the high-concentration ozone water cannot be used sufficiently.
[0005]
On the other hand, in JP-A-2001-77069 and JP-A-2001-156049, although the substrate is of a single-wafer type, when the substrate is heated, the heat capacity of the ozone water is about 1.0 cal / g · deg. Since the heat capacity of the substrate is 0.17 cal / g · deg, it is difficult to sufficiently heat the ozone water calorimetrically by simply bringing the ozone water into contact with the heated substrate, and the substrate is constantly heated from below or from above. It is necessary.
In addition, the table supporting the substrate is usually made of fluororesin, and in order to rapidly heat ozone water flowing at high speed over the substrate fixed to a rotary table or the like, to obtain an effective heat transfer speed required for it. Requires an excessive amount of heat. In the method of raising the temperature by spraying water vapor on the ozone water flowing down on the substrate, a temperature distribution of the ozone water may be generated in a radial direction of the substrate, and the processing speed may be uneven.
[0006]
[Problems to be solved by the invention]
The present invention provides a method for effectively heating high-concentration ozone water with a small amount of energy input, and by using the method for processing substrates and the like, improves the above-described problems in the conventional use of high-temperature ozone water. It is intended. In addition, compared with conventional chemical treatment under harsh conditions of high concentration and high temperature like sulfuric acid peroxide, technology that can improve the safety of treatment work, reduce rinsing load, reduce wastewater treatment load, etc. It is what we are going to offer.
[0007]
[Means for Solving the Problems]
The present invention relates to a treatment method for supplying or treating ozone water onto an object to be treated such as a substrate to treat or wash the surface of a substrate or the like. This is a method for treating an object to be treated using ozone water.
In other words, because ozone in water has the property of decomposing very quickly, instead of using an indirect method such as a heater to heat ozone water, steam is applied immediately before applying ozone water to the object to be treated. Are mixed, and the ozone water is rapidly heated and used by directly utilizing the heat of condensation of the steam.
[0008]
As the object to be treated in the present invention, many materials that perform treatment utilizing the strong oxidation characteristics of ozone water are used. In particular, as the semiconductor-related material which is highly required, a wafer as a semiconductor material substrate, a quartz plate as a mask material, and the like can be given. These materials undergo various processes such as cleaning of raw material wafers, application of resist, etching, element doping, resist peeling, and cleaning in the semiconductor manufacturing process. The use of water is progressing, development for it is being carried out, and practical use is also progressing.
[0009]
The mixing of the ozone water and the steam is desirably a method of directly flowing the steam into the supply line of the ozone water or a method of mixing by providing a mixer. It is also one of the preferable methods to use the flow rate of the ozone water in the supply line of the ozone water to suck the steam and mix the ozone water and the steam.
[0010]
As the vapor used in the present invention, various vapors can be selected depending on the intended use, such as organic solvent vapor or water vapor containing an organic solvent, water vapor containing an acid or alkali represented by hydrogen chloride or ammonia, or water vapor. . Among them, the use of steam is desirable from the viewpoint of high heat of condensation, easy handling, economical efficiency, and the like. In the case where water vapor is used for processing a semiconductor material, it is preferable to use pure water or ultrapure water in order to prevent contamination of a substrate or the like.
[0011]
On the other hand, ozone water can also be used depending on the purpose of use, for example, ozone water containing an acid or an alkali, as is often used in washing and dissolving operations.
In addition, an ozone decomposition inhibitor such as an acid, carbon dioxide, or an organic substance is often added to ozone water in order to suppress the decomposition of ozone in water. At room temperature, the effect of these inhibitors acts to reduce the rate of self-decomposition of ozone. However, when these ozone waters are heated to a high temperature, the decomposition rate of ozone increases at high temperatures, as can be predicted from general chemical reaction characteristics. Mixing and rapid heating is an effective method for effectively utilizing the oxidizing power of ozone. Details of these will be described later.
[0012]
The concentration of ozone water is not particularly limited, but the method of the present invention is more effective for an ozone water concentration of 20 ppm or more at which self-decomposition of ozone is activated.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have developed a method for efficiently producing high-concentration ozone water by preventing backmixing when producing ozone water using a packed tower. A patent application (JP-A-2000-167366) was filed for the equipment.
Thereafter, the present inventors succeeded in producing ultra-high concentration ozone water exceeding 100 ppm at room temperature using the above-mentioned ozone water production equipment, and using this ultra-high concentration ozone water, the self-decomposition rate and the organic matter on the substrate were reduced. As a result of examining the removal characteristics, etc., the decomposition rate of ultra-high concentration ozone water in ultrapure water at room temperature is extremely fast with a half-life of several seconds or less, and the removal characteristics of organic substances on the substrate Was found to be largely dependent on temperature.
[0014]
Thus, in order to effectively treat the substrate and the like with ozone water, it is preferable that the treatment is performed at a high temperature, that the temperature of the ozone water must be increased instantaneously without taking time, such as in an immersion type. An important factor in treatments that require a certain amount of residence time of ozone water is the inability to make full use of the strong oxidative decomposition characteristics of ultra-high concentration ozone water due to self-decomposition of ozone, especially at high temperatures. It was revealed.
[0015]
In view of the above results, the present inventors have developed a method of rapidly heating ozone water for single-wafer-type substrate processing and surface treatment of general materials, and directly mixing steam with ozone water of the present invention. The method of heating and using was completed.
[0016]
Hereinafter, the embodiment and operation of the present invention will be described using an example using ozone water produced by the facility disclosed in Japanese Patent Application Laid-Open No. 2000-167366, but the present invention does not depend on the method of producing ozone water. It is feasible and does not limit the invention.
[0017]
As steam, other than simple steam is also effective, but taking steam as a representative, steam at 100 ° C. has an enthalpy of 639.35 kcal / kg, and water at 80 ° C. has an enthalpy of 79.9993 kcal / kg. In order to raise the temperature of water at 20 ° C. (enthalpy of 20.030 kcal / kg) to 80 ° C., it is only necessary to add 0.107 kg / kg of steam, and the transfer of heat from steam to water is large. The portion is instantaneous because of the heat of condensation (latent heat of evaporation), and almost all the energy of the steam can be used.
[0018]
Further, since the weight of steam with respect to water is about 1/10, the decrease in ozone concentration diluted by adding steam is only about 10%, and steam can be produced from pure water or ultrapure water. Therefore, it is possible to produce a uniform heated ozone water with less contamination. As the heating temperature, a higher temperature is possible under pressure, but in the case of normal pressure, 50 to 95 ° C., preferably about 60 to 90 ° C. is appropriate in consideration of an increase in the reaction rate and ease of handling. .
[0019]
This heated ozone water becomes ozone water containing supersaturated ozone as a result, but is mixed with steam just before flowing down to the substrate or the like, and is self-decomposed by jetting to the substrate at a flow rate of about 2 to 10 m / s. It can be used for processing of substrates and the like with as little emission into the gas phase as possible.
[0020]
The heating was performed to more effectively use the strong oxidizing power of the ozone water, but the concentration of the ozone water is also important for increasing the processing speed, and the equipment according to claim 4 was used for the production of the ozone water. It is more effective to use high-concentration ozone water obtained as a result. That is, as described in detail in Japanese Patent Application Laid-Open No. 2000-167366, a water inlet and an exhaust gas outlet are provided at the upper part of the packed tower, and an ozone gas inlet and ozone water are taken out at the lower part of the packed tower. By providing two or more packed layers separated by a gas backflow prevention plate between them and providing ozone water with a packed tower type ozone water production facility that makes water and ozone gas contact in countercurrent, high concentration is achieved. Ozone water can be obtained efficiently.
[0021]
Adding an acid to the ozone water used for cleaning the substrate and the like is effective in increasing the cleaning ability and suppressing the self-decomposition of ozone. Examples of the acid include hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and organic acids. It is selected from acids (for example, formic acid, acetic acid, citric acid, etc.) and can be appropriately added according to the purpose.
[0022]
In addition, in order to suppress the self-decomposition of ozone in ozone water, a self-decomposition inhibitor is often added in advance. It is effective to add an acid, carbon dioxide (CO ₂ ) or an organic substance as a self-decomposition inhibitor of ozone water, and as the acid, there are hydrochloric acid, nitric acid, acetic acid, formic acid, etc., and as the organic substance, isopropyl alcohol, acetone, methyl Alcohol, ethyl alcohol and the like can be mentioned as examples. Any one or more of these can be used, and these may be used alone or in combination. By adding these self-decomposition inhibitors, the rate of autolysis of ozone at room temperature is considerably reduced, and it is effective even when heated as in the present invention.
[0023]
Next, an apparatus for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is an example of an apparatus for carrying out the present invention, and shows a conceptual diagram thereof.
The substrate 4 is fixed on the table 5 in FIG. 1, and the mechanism is such that ozone water and water vapor are mixed by the mixer 1, heated instantaneously, and immediately ejected from the nozzle 2 to the substrate 4.
As for the method of mixing the ozone water and the water vapor, it is only necessary to be able to perform uniform mixing in the shortest possible time, and examples thereof include a method of directly flowing the water vapor into the supply line of the ozone water or a method of providing a mixer and mixing. .
In FIG. 1, the mixer of the spray nozzle type has been described, but the mixer 1 may be of a type in which steam is simply introduced into the ozone water line. In addition, ozone water is often pressurized in order to produce high-concentration ozone water, and if the pressurized ozone water is used as it is, it is jetted at high speed from a nozzle. As an aspirator, a high-speed ozone water flow may be used to suck water vapor.
In addition, although the experiment was performed with one stationary nozzle, it is also possible to move the nozzle according to the purpose of application, or to perform the experiment with a plurality of nozzles.
[0024]
Embodiment 1
Using the apparatus shown in FIG. 1, a 1 μm resist was formed on the substrate, and a phosphorus (P) 1 × 10 ¹⁴ ions / cm ² implanted resist was subjected to a peel test. The resist stripping rate was calculated by measuring the resist film thickness before and after the treatment when heated ozone water was allowed to flow for a predetermined time. In the test, after setting the substrate 4 on the table 5 of the apparatus shown in FIG. 1 covered with a cover (not shown), ozone water and steam were mixed in the mixer 1 and instantaneously heated. Squirted up. The processing temperature is determined in advance by placing a thermometer at a position corresponding to the distance from the nozzle to the substrate in a state where the substrate is not installed, and determining the amount of steam necessary to heat the ozone water to the target temperature for a predetermined flow rate. The flow rate was set by flowing steam. Table 1 shows the results of a resist stripping test using ozone water having a concentration of 100 ppm.
[0025]

[0026]
Even though the ozone concentration in the ozone water is reduced by about 10% at the maximum by adding steam, a remarkable effect of removing and removing is obtained by heating. Further, from this example, it can be seen that the effect of ozone treatment can be obtained without impairing the effective ozone due to rapid heating with steam.
[0027]
In the above embodiment, the test was performed with the table and the substrate kept still. However, by rotating the table, the ozone water was renewed more quickly on the substrate surface, and a better effect can be expected.
[0028]
Embodiment 2
An experiment was performed using the same equipment and method as in Example 1 while changing the ozone water concentration to be supplied by setting the temperature of the heated ozone water by steam to 80 ° C. Samples used were resist (1μm) 1 × ¹⁰ 14 phosphorus ions / cm ² implant samples on the substrate in the same manner as in Example 1. Table 2 shows the obtained results.
[0029]

[0030]
The hot water of 80 ° C., which is a comparative example, had no effect on the peeling of the resist, and the heated ozone water was effective for the peeling of the resist. The stripping rate increases linearly with the increase in ozone concentration.
[0031]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to process the surface of a board | substrate, a mask material, etc. effectively using the oxidizing power of the ozone which increased by heating. The method of the present invention replaces the non-uniform or excessive energy consuming methods, such as conventional plasma ashing and sulfuric acid peroxide, and the method requiring a large amount of rinsing water and the costly wastewater treatment. This is a new treatment method, and can greatly reduce the treatment time compared to conventional ozone water at normal temperature, which is a great benefit.
[Brief description of the drawings]
FIG. 1 is an example of a conceptual diagram of an apparatus for implementing the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Mixer 2 Jet nozzle 3 Heated ozone water 4 Substrate to be processed 5 Table

Claims

A method for treating or cleaning the surface of an object to be treated by supplying ozone water onto the object to be treated, characterized in that the steam is mixed and heated immediately before the supply of the ozone water and used. Ozone water heat treatment method.

The method of claim 1, wherein the object to be processed is a semiconductor-related material.

3. The method according to claim 1, wherein the steam is steam.

The ozone water has an inlet for water and an outlet for exhaust gas at the top of the packed tower, and an inlet for ozone gas and an outlet for ozone water at the bottom of the packed tower. The ozone water heat treatment method according to any one of claims 1 to 3, wherein the ozone water is an ozone water produced by a packed tower type ozone water production facility in which two or more water and ozone gas are brought into countercurrent contact with each other.

5. The heat treatment method for ozone water according to claim 1, wherein the mixing of the ozone water and the steam is a method of directly flowing the steam into a supply line of the ozone water or a method of mixing by providing a mixer.

The ozone water heating method according to claim 5, wherein the steam is sucked by utilizing the flow rate of the ozone water in the ozone water supply line, and the ozone water and the steam are mixed.

The heat treatment method for ozone water according to any one of claims 1 to 6, wherein ozone water containing an acid or an alkali is used.

The ozone water heat treatment method according to any one of claims 1 to 7, wherein the ozone water contains an ozone decomposition inhibitor.

9. The heat treatment method for ozone water according to claim 8, wherein the ozone decomposition inhibitor is at least one of an acid, carbon dioxide, and an organic substance.

10. The heat treatment method for ozone water according to claim 9, wherein the organic substance is at least one of isopropyl alcohol, acetone, methyl alcohol, and ethyl alcohol.