JP3559426B2 - Corrosion resistant materials - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、ハロゲン系腐食性ガスが存在する雰囲気下でのプラズマに対して優れた耐食性を有する耐食性部材を提供せんとするものであり、例えば、半導体製造用や液晶プロセス用のプラズマ装置に使用されるウエハ保持具やクランプリング等の治具や内壁材、あるいはフロンガス分解処理装置やエキシマレーザーのレーザー管等として好適に使用できるものである。
【０００２】
【従来の技術】
従来、半導体装置の製造工程におけるプラズマプロセスとして、フッ素系や塩素系等のハロゲン系腐食性ガスが、その反応性の高さから、気相成長、エッチングやクリーニングに利用されている。
【０００３】
そして、これらのハロゲン系腐食性ガス下でプラズマに曝される部材には耐食性が要求されることから、石英ガラス、あるいはステンレスやアルミニウム等の耐食軽金属材、さらにはアルミナ焼結体や窒化アルミニウム焼結体、及びこれらセラミック焼結体に炭化珪素等のセラミック膜を被覆したものが使用されていた（特公平５−５３８７２号、特開平３−２１７０１６号、特開平８−９１９３２号公報参照。）
【０００４】
【発明が解決しようとする課題】
しかしながら、耐蝕性部材として石英ガラスを用いたものでは、プラズマ中での耐食性が不充分であることからハロゲンプラズマに曝されると、プラズマとの接触部が激しくエッチングされて消耗するといった課題があった。
【０００５】
また、耐蝕性部材としてステンレスやアルミニウム等の耐食軽金属材を用いたものにおいても耐食性が不充分で、特に耐食軽金属材が腐食を受けると半導体装置の製造において、ウエハに悪影響を与える恐れが高いために不良品発生の原因となるといった課題があった。
【０００６】
また、耐蝕性部材としてアルミナ焼結体や窒化アルミニウム焼結体、あるいは上記セラミック焼結体にセラミック膜を被覆したものでは、石英ガラスや耐食軽金属材と比較してハロゲン系腐食性ガスに対して高い耐食性を有しているものの、高温でプラズマと接すると腐食が徐々に進行してセラミック焼結体の表面からハロゲン化物が蒸発あるいは微粉体となって消耗するといった課題があり、さらに耐食性の高い材質が望まれていた。
【０００７】
【課題を解決するための手段】
そこで、本件出願人は、ハロゲン系腐食性ガスを含む雰囲気下でプラズマに曝されたとしても優れた耐食性を有する材質について検討を重ねた結果、マグネシウム（Ｍｇ）の化合物を含むセラミック焼結体がハロゲン系腐食性ガスと反応してハロゲン化物を生成したとしても融点が高く安定であることから、耐蝕性に優れることを見出した。
【０００８】
また、セラミック焼結体に多数の気孔が存在したり、粒界相が多いと腐食を受けやすく、耐食性が大きく低下することを見出した。
【０００９】
即ち、本発明は、フッ素系や塩素系等のハロゲン系腐食性ガスを含む雰囲気下でプラズマに曝される耐蝕性部材を、酸化物換算でＭｇＯを１５重量％以上、Ａｌ２Ｏ３を８５重量％以下の範囲とし、ＭｇＯ、ＭｇＡｌ２Ｏ４とＭｇＯ、ＭｇＡｌ２Ｏ４、ＭｇＡｌ２Ｏ４とＡｌ２Ｏ３のいずれかの結晶相からなり、上記結晶相の平均結晶粒子径が１５μｍ以上でかつ気孔率が０．１％以下であるセラミック焼結体からなることを特徴とする。
【００１０】
【発明の実施の形態】
本発明の耐食性部材は、ハロゲン系腐食性ガス下でプラズマに曝される部材であり、ハロゲン系腐食性ガスとしては、ＳＦ６ 、ＣＦ４ 、ＣＨＦ３ 、ＣＩＦ３ 、ＨＦ等のフッ素系ガス、Ｃｌ２ 、ＢＣｌ３ 、ＨＣｌ、ＣＣｌ４ 等の塩素系ガス、あるいはＢｒ２ 、ＨＢｒ、ＣＢｒ４ 等の臭素系ガスなどがある。そして、これらのハロゲン系腐食性ガスが使用される雰囲気下で高周波やマイクロ波が導入されるとこれらのガスがプラズマ化されることになる。
【００１１】
また、エッチング効果をより高めるために、ハロゲン系腐食性ガスとともに、Ａｒなどの不活性ガスを導入してプラズマを発生させることもある。
【００１２】
本発明は、これらのハロゲン系腐食性ガス下でプラズマに曝される耐食性部材を、ＭｇＯ、ＭｇＡｌ２ Ｏ４ とＭｇＯ、ＭｇＡｌ２ Ｏ４ 、ＭｇＡｌ２ Ｏ４ とＡｌ２ Ｏ３ のいずれかの結晶相からなるセラミック焼結体により形成したものである。
【００１３】
即ち、セラミック焼結体の結晶相を構成するＭｇＯやＭｇＡｌ２ Ｏ４ は、フッ素系ガスと反応すると主にＭｇＦ２ を生成し、また、塩素系ガスと反応すると主にＭｇＣｌ２ を生成するが、これらのハロゲン化物の融点（ＭｇＦ２ ：１２６０℃，ＭｇＣｌ２ ：７１４℃）は、従来の石英ガラスあるいはアルミナ焼結体や窒化アルミニウム焼結体との反応により生成されるハロゲン化物の融点（ＳｉＦ４ ：−９０℃，ＳｉＣｌ４ ：−７０℃，ＡｌＦ３ ：１０４０℃，ＡｌＣｌ３ ：１７８℃）より高いために、高温でプラズマに曝されたとしても安定した耐熱性と耐食性を兼ね備えており、ハロゲン系腐食性ガス下でのプラズマに対する耐食性を高めることができる。
【００１４】
ここで、ＭｇＡｌ２ Ｏ４ とは、ＭｇＯとＡｌ２ Ｏ３ の理論定比が、重量比で２８．６：７１．４（モル比で１：１）で結合した化合物のことである。そして、ＭｇＯとＡｌ２ Ｏ３ の組成比率を種々変化させると、理論定比では実質的にＭｇＡｌ２ Ｏ４ 結晶のみが存在するが、理論定比よりＭｇＯを多くするとＭｇＯとＭｇＡｌ２ Ｏ４ の二相結晶構造となり、一方、理論定比よりＡｌ２ Ｏ３ を多くするとＡｌ２ Ｏ３ とＭｇＡｌ２ Ｏ４ の二相結晶構造となる。
【００１５】
そして、本件出願人は、ＭｇＯ、ＭｇＡｌ２Ｏ４とＭｇＯ、ＭｇＡｌ２Ｏ４、ＭｇＡｌ２Ｏ４とＡｌ２Ｏ３のいずれかの結晶相からなるセラミック焼結体の含有量を、酸化物換算でＭｇＯを１５重量％以上、Ａｌ２Ｏ３を８５重量％以下とすることにより、ハロゲン系腐食性ガス下でのプラズマに対して優れた耐食性を有する耐食性部材が得られることを見出したものである。
【００１６】
即ち、酸化物換算でのＭｇＯの含有量が１５重量％未満となる（酸化物換算でのＡｌ２ Ｏ３ の含有量が８５重量％より多くなる）と、セラミック焼結体中におけるＡｌ２ Ｏ３ 結晶相の量が多くなり過ぎるために、ハロゲンプラズマによる腐食を受けやすくなるからである。
【００１７】
また、耐食性部材を構成するセラミック焼結体の耐食性を高めるためには、気孔率を０．２％以下とするとともに、セラミック焼結体を構成するＭｇＯ、ＭｇＡｌ２ Ｏ４ 、Ａｌ２ Ｏ３ の平均結晶粒子径を３μｍ以上、好ましくは気孔率を０．１％以下、ＭｇＯ、ＭｇＡｌ２ Ｏ４ 、Ａｌ２ Ｏ３ の平均結晶粒子径を１５μｍ以上とすることが良い。
【００１８】
これは、セラミック焼結体に気孔が存在すると、気孔のエッジがプラズマにより浸食を受け易く、気孔率が０．２％を越えると、腐食の進行が加速されるからであり、ＭｇＯ、ＭｇＡｌ２ Ｏ４ 、Ａｌ２ Ｏ３ の平均結晶粒子径が３μｍ未満であるとプラズマにより腐食を受けやすい粒界相が多くなるとともに、気孔率を０．２％以下とすることができないためである。
【００１９】
なお、本発明における結晶相の平均結晶粒子径とは、ＭｇＯあるいはＭｇＡｌ２ Ｏ４ を主体とするセラミック焼結体の場合、ＭｇＯ結晶あるいはＭｇＡｌ２ Ｏ４ 結晶の平均結晶粒子径のことであり、ＭｇＡｌ２ Ｏ４ とＭｇＯあるいはＭｇＡｌ２ Ｏ４ とＡｌ２ Ｏ３ を主体とするセラミック焼結体の場合、ＭｇＡｌ２ Ｏ４ 結晶とＭｇＯ結晶あるいはＭｇＡｌ２ Ｏ４ 結晶とＡｌ２ Ｏ３ 結晶をまとめて測定した時の平均結晶粒子径のことである。そして、平均結晶粒子径を測定する方法としては、耐食性部材の任意の表面又は断面を金属顕微鏡又は電子顕微鏡（ＳＥＭ）で拡大し、画像解析装置により分析することで求めることができるが、簡易的に、耐食性部材の任意の表面又は断面を拡大したＳＥＭ写真を用意し、このＳＥＭ写真に１０本の線を任意に引いたあと、線の全長を線上に位置する結晶数で除した値を平均結晶粒子径としても良い。
【００２０】
また、セラミック焼結体の気孔率についてはアルキメデス法で、結晶相についてはＸ線回折で、含有量についてはＩＣＰ又は蛍光Ｘ線によりそれぞれ求めることができる。
【００２１】
さらに、耐食性部材を構成するセラミック焼結体には、ＳｉＯ２ 、ＣａＯ、Ｎａ２ Ｏ、Ｆｅ２ Ｏ３ 等が不純物成分として含まれることがあるが、これらの不純物成分とハロゲン系腐食性ガスとの反応により生成されるハロゲン化物の融点はそれほど高くないことから、不純物量が主要成分をなすＡｌ２ Ｏ３ とＭｇＯの合計１００重量部に対し、１重量部より多く含まれると大きく腐食を受けることになる。
【００２２】
その為、これら不純物量は主要成分をなすＡｌ２ Ｏ３ とＭｇＯの合計１００重量部に対し、１重量部以下とすることが望ましく、この不純物量を１重量部以下とするには、出発原料に高純度のＡｌ２ Ｏ３ とＭｇＯを使用するとともに、製造工程中における不純物の混入を防止するようにすれば良い。
【００２３】
以下、本発明に係る耐食性部材の製造方法を説明する。
【００２４】
まず、純度が９９％以上でかつ平均粒径が０．１〜５μｍのＡｌ２ Ｏ３ を８５重量％未満と、純度が９９％以上でかつ平均粒径が０．１〜５μｍのＭｇＯを１５重量％以上の割合で添加し、さらにバインダーと溶媒を加えて混合することにより泥漿を作製し、この泥漿を押出成形法や射出成形法、あるいはドクターブレード法など公知のセラミック成形手段により所定の形状に成形するか、あるいは上記泥漿をスプレードライヤで造粒して顆粒を作製したあと、型内に充填して金型プレス成形法やラバープレス成形法により所定の形状に成形する。
【００２５】
しかるのち、これらの成形体を大気雰囲気下や真空雰囲気下にて１５００〜１７００℃の温度で１〜１０時間程度焼成することにより、ＭｇＯ、ＭｇＡｌ２ Ｏ４ とＭｇＯ、ＭｇＡｌ２ Ｏ４ 、ＭｇＡｌ２ Ｏ４ とＡｌ２ Ｏ３ のいずれかの結晶相からなる耐食性部材を得ることができる。
【００２６】
（実施例１）
本発明の耐食性部材として、ＭｇＡｌ２ Ｏ４ とＭｇＯの結晶相からなるセラミック焼結体と、従来の耐食性部材として、石英ガラス、純度９９．５％のアルミナ焼結体、及び純度９９．９％のアルミナ焼結体をそれぞれ用意し、フッ素系及び塩素系の腐食性ガス下でプラズマに曝した時の耐食性について実験を行った。
【００２７】
本実験では、本発明及び従来の耐食性部材を直径３０ｍｍ×厚さ３ｍｍに形成したあと、ラップ加工を施して表面を鏡面にしたものを試料とし、この試料をＲＩＥプラズマ装置に設置してＳＦ６ ガス雰囲気下及びＣｌ２ ガス雰囲気下でそれぞれ高周波を導入してプラズマを発生させ、これらのプラズマ中で３時間曝したあと、処理前後の重量の減少量から１分間当たりのエッチングレートを算出した。
【００２８】
なお、本発明の耐食性部材には、Ａｌ２ Ｏ３ ７０重量％、ＭｇＯ３０重量％に対し、溶媒とバインダーを加えて約１０時間混合したあと、スプレードライヤで造粒して顆粒を作製し、この顆粒を金型内に充填してメカプレス法により１．０ｔｏｎ／ｃｍ２ 程度の圧力で加圧することにより円柱状体を成形し、しかるのち、大気雰囲気中にて１７００℃の温度で２時間焼成することにより製作したものを使用した。
【００２９】
各試料の特性及びそれぞれの結果は表１に示す通りである。
【００３０】
【表１】
この結果、本発明の耐食性部材は、ＳＦ６ ガス及びＣｌ２ ガスのいずれの腐食性ガスに対してもエッチングレートを２０Å／ｍｉｎ以下とすることができ、従来の耐食性部材と比較して優れた耐食性を有していた。
【００３２】
（実施例２）
次に、耐食性部材として、Ａｌ２ Ｏ３ とＭｇＯの含有量をそれぞれ異ならせて製作したＭｇＯ、ＭｇＡｌ２ Ｏ４ とＭｇＯ、ＭｇＡｌ２ Ｏ４ 、ＭｇＡｌ２ Ｏ４ とＡｌ２ Ｏ３ のいずれかの結晶相からなるセラミック焼結体を製作し、フッ素系及び塩素系の腐食性ガス下でプラズマに曝した時の耐食性について実験を行った。
【００３３】
本実験では、Ａｌ２ Ｏ３ とＭｇＯをそれぞれ表１に示す割合で添加し、さらに溶媒とバインダーを加えて約１０時間混合したあと、スプレードライヤで造粒して顆粒を作製し、この顆粒を金型内に充填してメカプレス法により１．０ｔｏｎ／ｃｍ２ 程度の圧力で加圧することにより円柱状体を成形し、しかるのち、大気雰囲気中にて１７００℃の温度で２時間焼成することで製作したものを使用した。
【００３４】
そして、これらのセラミック焼結体を直径３０ｍｍ×厚さ３ｍｍに切削したあと、ラップ加工を施して表面を鏡面に仕上げたものを試料とし、これらの試料をＲＩＥプラズマ装置に設置してＳＦ６ ガス雰囲気下及びＣｌ２ ガス雰囲気下でそれぞれ高周波を導入してプラズマを発生させ、これらのプラズマ中で３時間曝したあと、処理前後の重量の減少量から１分間当たりのエッチングレートを算出した。
【００３５】
各試料の特性を表２に、それぞれの結果を表３に示す。
【００３６】
【表２】
【表３】
この結果、ＭｇＯが１５重量％未満（Ａｌ２ Ｏ３ が８５重量％より多い）では、セラミック焼結体中のＡｌ２ Ｏ３ 結晶量が多いために、ＳＦ６ ガス雰囲気下のエッチングレートが７０Å／ｍｉｎ、Ｃｌ２ ガス雰囲気下のエッチングレートが１２０Å／ｍｉｎ程度と、実施例１で用いた純度９９．９％のアルミナ焼結体と同程度の耐食性であった。
【００３９】
これに対し、ＭｇＯを１５重量％以上（Ａｌ２ Ｏ３ を８５重量％以下）したものでは、ＳＦ６ ガス雰囲気下での腐食を３０Å／ｍｉｎ以下、Ｃｌ２ ガス雰囲気下での腐食を５０Å／ｍｉｎ以下とすることができ、優れた耐食性を有していた。特に、ＭｇＯを３０重量％以上（Ａｌ２ Ｏ３ を７０重量％以下）としたものでは、ＳＦ６ ガス及びＣｌ２ ガス雰囲気下での腐食を２０Å／ｍｉｎ以下とすることができ、さらに、ＭｇＯのみからなるセラミック焼結体ではＳＦ６ ガス及びＣｌ２ ガス雰囲気下での腐食を５Å／ｍｉｎとすることができた。
【００４０】
（実施例３）
さらに、表２の試料Ｎｏ．３におけるセラミック焼結体を用い、焼成温度を制御して気孔率及び平均粒子径を異ならせた時の耐食性について実施例１と同様の条件にて実験を行った。
【００４１】
セラミック焼結体の気孔率及び平均粒子径を表４に、その結果を表５に示す。
【００４２】
【表４】
【表５】
この結果、試料Ａ，Ｂ，Ｃは、いずれも気孔率が０．１％より大きく、また、ＭｇＡｌ２Ｏ４及びＭｇＯの平均結晶粒子径が１５μｍ未満であるために、気孔のエッジや粒界相部分が浸食を受け、大きく腐食した。
【００４５】
これに対し、試料Ｄ〜Ｆは、気孔率が０．１％以下、ＭｇＡｌ２Ｏ４結晶とＭｇＯ結晶の平均結晶粒子径が１５μｍ以上であるため、ＳＦ６ガス雰囲気下での腐食が３０Å／ｍｉｎ以下、Ｃｌ２ガス雰囲気下での腐食が５０Å／ｍｉｎ以下と優れた耐食性を有していた。
【００４６】
また、本実験における結晶相の平均結晶粒子径と気孔率の関係は、表２の試料Ｎｏ．１，２，４〜８のセラミック焼結体においても同様の傾向が見られた。
【００４７】
【発明の効果】
以上のように、本発明によれば、耐食性部材を、酸化物換算でＭｇＯを１５重量％以上、Ａｌ２Ｏ３を８５重量％以下の範囲とし、ＭｇＯ、ＭｇＡｌ２Ｏ４とＭｇＯ、ＭｇＡｌ２Ｏ４、ＭｇＡｌ２Ｏ４とＡｌ２Ｏ３のいずれかの結晶相からなり、上記結晶相の平均結晶粒子径が１５μｍ以上でかつ気孔率が０．１％以下であるセラミック焼結体により形成したことから、フッ素系や塩素系等のハロゲン系腐食性ガスが存在する雰囲気下でプラズマに曝されたとしても優れた耐食性を有し、例えば、プラズマ装置に使用されるウエハ保持具やクランプリング等の治具や内壁材、あるいはフロンガス分解処理装置やエキシマレーザーに使用されるプラズマ発生用保護管等の部材として好適に使用することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
An object of the present invention is to provide a corrosion-resistant member having excellent corrosion resistance to plasma in an atmosphere in which a halogen-based corrosive gas is present. For example, the present invention is used for a plasma device for semiconductor production or a liquid crystal process. It can be suitably used as a jig such as a wafer holder and a clamp ring, an inner wall material, a fluorocarbon gas decomposition processing apparatus, a laser tube of an excimer laser, and the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a plasma process in a semiconductor device manufacturing process, a halogen-based corrosive gas such as a fluorine-based gas and a chlorine-based gas has been used for vapor-phase growth, etching, and cleaning due to its high reactivity.
[0003]
Since the members exposed to plasma under these halogen-based corrosive gases are required to have corrosion resistance, quartz glass, corrosion-resistant light metal materials such as stainless steel and aluminum, and sintered alumina or aluminum nitride are required. A sintered body and a ceramic sintered body coated with a ceramic film such as silicon carbide have been used (see Japanese Patent Publication No. 5-53872, Japanese Patent Application Laid-Open No. 3-217016, and Japanese Patent Application Laid-Open No. 8-91932).
[0004]
[Problems to be solved by the invention]
However, in the case of using quartz glass as a corrosion-resistant member, the corrosion resistance in plasma is insufficient, so that when exposed to halogen plasma, there is a problem that a contact portion with plasma is severely etched and consumed. Was.
[0005]
Further, even when a corrosion-resistant light metal material such as stainless steel or aluminum is used as the corrosion-resistant member, the corrosion resistance is insufficient. There is a problem that this may cause defective products.
[0006]
In addition, in the case of an alumina sintered body or aluminum nitride sintered body as a corrosion-resistant member, or the above-mentioned ceramic sintered body coated with a ceramic film, it is more resistant to halogen-based corrosive gases than quartz glass and corrosion-resistant light metal materials. Despite having high corrosion resistance, there is a problem that when it comes into contact with plasma at high temperature, corrosion gradually progresses and the halide evaporates or becomes fine powder from the surface of the ceramic sintered body and is consumed. The material was desired.
[0007]
[Means for Solving the Problems]
Accordingly, the applicant has repeatedly studied materials having excellent corrosion resistance even when exposed to plasma in an atmosphere containing a halogen-based corrosive gas. As a result, a ceramic sintered body containing a magnesium (Mg) compound was obtained. It has been found that even when a halide is produced by reacting with a halogen-based corrosive gas, the melting point is high and the material is stable, so that it has excellent corrosion resistance.
[0008]
Further, they have found that when a large number of pores are present in the ceramic sintered body or when there are many grain boundary phases, the ceramics are susceptible to corrosion and the corrosion resistance is greatly reduced.
[0009]
That is, according to the present invention, a corrosion-resistant member exposed to plasma in an atmosphere containing a halogen-based corrosive gas such as a fluorine-based gas and a chlorine-based gas is prepared by converting 15% by weight or more of MgO and 85% of Al 2 O 3 in terms of oxide. a weight percent range, MgO, MgAl 2 O 4 and MgO, consists MgAl 2 O 4, MgAl 2 O 4 and any crystalline phase of Al 2 O 3, the average crystal grain size of the crystalline phase 15 [mu] m It is characterized by being made of a ceramic sintered body having a porosity of 0.1 % or less.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The corrosion-resistant member of the present invention is a member exposed to plasma under a halogen-based corrosive gas. Examples of the halogen-based corrosive gas include fluorine-based gases such as SF 6 , CF 4 , CHF 3 , CIF 3 , and HF. There are chlorine-based gases such as Cl 2 , BCl 3 , HCl, and CCl 4 , and bromine-based gases such as Br 2 , HBr, and CBr 4 . When high-frequency waves or microwaves are introduced in an atmosphere in which these halogen-based corrosive gases are used, these gases are turned into plasma.
[0011]
In order to further enhance the etching effect, an inert gas such as Ar may be introduced together with the halogen-based corrosive gas to generate plasma.
[0012]
The present invention provides a corrosion-resistant member exposed to plasma under these halogen-based corrosive gases by using any one of MgO, MgAl 2 O 4 and MgO, MgAl 2 O 4 , and any one of MgAl 2 O 4 and Al 2 O 3. It is formed by a ceramic sintered body composed of phases.
[0013]
That is, MgO or MgAl 2 O 4 constituting the crystal phase of the ceramic sintered body mainly generates MgF 2 when reacted with a fluorine-based gas, and mainly generates MgCl 2 when reacted with a chlorine-based gas. The melting points of these halides (MgF 2 : 1260 ° C., MgCl 2 : 714 ° C.) are the melting points (SiF 2) of the halides formed by the reaction with conventional quartz glass or sintered alumina or sintered aluminum nitride. 4: -90 ℃, SiCl 4: -70 ℃, AlF 3: 1040 ℃, AlCl 3: for higher than 178 ° C.), and also has a stable heat resistance and corrosion resistance as was exposed to the plasma at a high temperature, Corrosion resistance to plasma under a halogen-based corrosive gas can be increased.
[0014]
Here, MgAl 2 O 4 is a compound in which the theoretical stoichiometric ratio of MgO and Al 2 O 3 is 28.6: 71.4 by weight (1: 1 by mole). When the composition ratio of MgO and Al 2 O 3 is variously changed, only MgAl 2 O 4 crystals are substantially present at the theoretical stoichiometric ratio. However, when MgO is increased more than the theoretical stoichiometric ratio, MgO and MgAl 2 O 4 are mixed. A two-phase crystal structure is formed. On the other hand, when Al 2 O 3 is increased more than the theoretical stoichiometric ratio, a two-phase crystal structure of Al 2 O 3 and MgAl 2 O 4 is formed.
[0015]
The applicant of the present invention has calculated the content of a ceramic sintered body composed of any one of MgO, MgAl 2 O 4 and MgO, MgAl 2 O 4 , and any crystal phase of MgAl 2 O 4 and Al 2 O 3 in terms of oxide. It has been found that by setting MgO to 15% by weight or more and Al 2 O 3 to 85% by weight or less , a corrosion-resistant member having excellent corrosion resistance to plasma under a halogen-based corrosive gas can be obtained. is there.
[0016]
That is, when the content of MgO in terms of oxide is less than 15% by weight (the content of Al 2 O 3 in terms of oxide is more than 85% by weight), Al 2 O in the ceramic sintered body is reduced. This is because the amount of the three crystal phases becomes too large, so that it becomes susceptible to corrosion by halogen plasma.
[0017]
Further, in order to increase the corrosion resistance of the ceramic sintered body constituting the corrosion resistant member, the porosity is set to 0.2% or less, and MgO, MgAl 2 O 4 , Al 2 O 3 constituting the ceramic sintered body are reduced. It is preferable that the average crystal particle diameter is 3 μm or more, preferably the porosity is 0.1% or less, and the average crystal particle diameter of MgO, MgAl 2 O 4 and Al 2 O 3 is 15 μm or more.
[0018]
This is because when the pore is present in the ceramic sintered body, easy pore edges eroded by plasma, when the porosity exceeds 0.2%, is because the progress of corrosion is accelerated, MgO, MgAl 2 If the average crystal particle diameter of O 4 and Al 2 O 3 is less than 3 μm, the number of grain boundary phases which are susceptible to corrosion by plasma increases, and the porosity cannot be reduced to 0.2% or less.
[0019]
Note that the average crystal grain size of the crystal phase in the present invention, when the ceramic sintered body consisting mainly of MgO or MgAl 2 O 4, is that the average crystal grain size of the MgO crystal or MgAl 2 O 4 crystal, In the case of a ceramic sintered body mainly composed of MgAl 2 O 4 and MgO or MgAl 2 O 4 and Al 2 O 3 , MgAl 2 O 4 crystal and MgO crystal or MgAl 2 O 4 crystal and Al 2 O 3 crystal are collected together. It is the average crystal particle diameter measured. As a method of measuring the average crystal particle diameter, it can be obtained by enlarging an arbitrary surface or cross section of the corrosion-resistant member with a metal microscope or an electron microscope (SEM) and analyzing it with an image analyzer. An SEM photograph in which an arbitrary surface or cross section of the corrosion-resistant member is enlarged is prepared, and ten lines are arbitrarily drawn on the SEM photograph, and the value obtained by dividing the total length of the line by the number of crystals located on the line is averaged. The crystal particle diameter may be used.
[0020]
The porosity of the ceramic sintered body can be determined by Archimedes' method, the crystal phase can be determined by X-ray diffraction, and the content can be determined by ICP or fluorescent X-ray.
[0021]
Further, the ceramic sintered body constituting the corrosion resistant member may contain SiO 2 , CaO, Na 2 O, Fe 2 O 3, and the like as impurity components. Since the melting point of the halide produced by the above reaction is not so high, if the amount of impurities is more than 1 part by weight with respect to the total of 100 parts by weight of Al 2 O 3 and MgO, which are the main components, it is greatly corroded. Will be.
[0022]
Therefore, the amount of these impurities is desirably 1 part by weight or less with respect to the total of 100 parts by weight of Al 2 O 3 and MgO which are the main components. High-purity Al 2 O 3 and MgO may be used to prevent impurities from being mixed during the manufacturing process.
[0023]
Hereinafter, a method for manufacturing a corrosion-resistant member according to the present invention will be described.
[0024]
First, less than 85% by weight of Al 2 O 3 having a purity of 99% or more and an average particle size of 0.1 to 5 μm, and MgO having a purity of 99% or more and an average particle size of 0.1 to 5 μm are added. Weight percent or more, and further, a binder and a solvent are added and mixed to form a slurry, and the slurry is formed into a predetermined shape by a known ceramic molding means such as an extrusion molding method, an injection molding method, or a doctor blade method. Alternatively, the slurry is granulated by a spray dryer to form granules, and then filled into a mold and formed into a predetermined shape by a die press molding method or a rubber press molding method.
[0025]
Thereafter, these compacts are fired at a temperature of 1500 to 1700 ° C. for about 1 to 10 hours under an air atmosphere or a vacuum atmosphere, so that MgO, MgAl 2 O 4 and MgO, MgAl 2 O 4 , MgAl 2 It is possible to obtain a corrosion-resistant member made of any one of the crystal phases of O 4 and Al 2 O 3 .
[0026]
(Example 1)
A ceramic sintered body composed of a crystal phase of MgAl 2 O 4 and MgO as the corrosion resistant member of the present invention, and quartz glass, a 99.5% pure alumina sintered body, and a purity of 99.9% as the conventional corrosion resistant member. Were prepared, and an experiment was conducted on corrosion resistance when exposed to plasma under a fluorine-based and chlorine-based corrosive gas.
[0027]
In this experiment, after the present invention and the conventional anti-corrosion member was formed with a diameter 30 mm × thickness 3 mm, a material obtained by the surface mirror is subjected to lapping and sample, SF 6 by installing this sample RIE plasma device Plasma was generated by introducing high frequency waves in a gas atmosphere and a Cl 2 gas atmosphere, respectively, and after exposure for 3 hours in these plasmas, the etching rate per minute was calculated from the weight loss before and after the treatment.
[0028]
The corrosion-resistant member of the present invention was prepared by adding a solvent and a binder to 70% by weight of Al 2 O 3 and 30% by weight of MgO and mixing them for about 10 hours, and then granulating with a spray dryer to produce granules. The granules are filled in a mold and pressurized at a pressure of about 1.0 ton / cm 2 by a mechanical press method to form a columnar body, and then fired at 1700 ° C. for 2 hours in an air atmosphere. What was manufactured by using it was used.
[0029]
The properties of each sample and the results are as shown in Table 1.
[0030]
[Table 1]
As a result, the corrosion-resistant member of the present invention can have an etching rate of 20 ° / min or less for both corrosive gas of SF 6 gas and Cl 2 gas, and is superior to the conventional corrosion-resistant member. It had corrosion resistance.
[0032]
(Example 2)
Next, as a corrosion-resistant member, any one of MgO, MgAl 2 O 4 and MgO, MgAl 2 O 4 , and MgAl 2 O 4 and Al 2 O 3 manufactured with different contents of Al 2 O 3 and MgO respectively was used. A ceramic sintered body composed of a crystalline phase was fabricated, and an experiment was performed on the corrosion resistance when exposed to plasma under a fluorine-based or chlorine-based corrosive gas.
[0033]
In this experiment, Al 2 O 3 and MgO were added in the proportions shown in Table 1, respectively, and a solvent and a binder were added and mixed for about 10 hours, and then granulated by a spray dryer to produce granules. A cylindrical body is formed by filling in a mold and pressing at a pressure of about 1.0 ton / cm 2 by a mechanical press method, and then firing at 1700 ° C. for 2 hours in an air atmosphere. The manufactured one was used.
[0034]
Then, after cutting these ceramic sintered bodies to a diameter of 30 mm × thickness of 3 mm, lapping was performed to obtain a mirror-finished surface, and these samples were placed in an RIE plasma apparatus to obtain SF 6 gas. Plasma was generated by introducing high frequency waves in an atmosphere and in a Cl 2 gas atmosphere, and after exposure for 3 hours in these plasmas, the etching rate per minute was calculated from the weight loss before and after the treatment.
[0035]
Table 2 shows the characteristics of each sample, and Table 3 shows the results.
[0036]
[Table 2]
[Table 3]
As a result, when the content of MgO is less than 15% by weight (the content of Al 2 O 3 is more than 85% by weight), since the amount of Al 2 O 3 crystals in the ceramic sintered body is large, the etching rate in an atmosphere of SF 6 gas is 70 °. / Min, the etching rate in a Cl 2 gas atmosphere was about 120 ° / min, and the corrosion resistance was about the same as that of the 99.9% pure alumina sintered body used in Example 1.
[0039]
On the other hand, in the case of MgO of 15% by weight or more (Al 2 O 3 of 85% by weight or less), corrosion in SF 6 gas atmosphere is 30 ° / min or less, and corrosion in Cl 2 gas atmosphere is 50 ° / min. min or less, and had excellent corrosion resistance. In particular, when the content of MgO is 30% by weight or more (the content of Al 2 O 3 is 70% by weight or less), corrosion in an atmosphere of SF 6 gas and Cl 2 gas can be reduced to 20 ° / min or less. In the case of the ceramic sintered body composed of only the material, corrosion in an atmosphere of SF 6 gas and Cl 2 gas could be reduced to 5 ° / min.
[0040]
(Example 3)
Further, the sample Nos. An experiment was performed on the corrosion resistance when the porosity and the average particle diameter were varied by controlling the firing temperature using the ceramic sintered body of Example 3 under the same conditions as in Example 1.
[0041]
Table 4 shows the porosity and average particle size of the ceramic sintered body, and Table 5 shows the results.
[0042]
[Table 4]
[Table 5]
As a result, the samples A, B, and C all had a porosity of more than 0.1 %, and the average crystal particle diameter of MgAl 2 O 4 and MgO was less than 15 μm. The boundary phase was eroded and corroded significantly.
[0045]
On the other hand, since Samples D to F have a porosity of 0.1 % or less and an average crystal particle diameter of MgAl 2 O 4 crystal and MgO crystal of 15 μm or more, corrosion in SF 6 gas atmosphere is 30 ° C. / Min or less, corrosion in a Cl 2 gas atmosphere was 50 ° / min or less, indicating excellent corrosion resistance.
[0046]
The relationship between the average crystal grain size of the crystal phase and the porosity in this experiment is shown in Table 2 for sample No. A similar tendency was observed in the ceramic sintered bodies of 1, 2, 4 to 8.
[0047]
【The invention's effect】
As described above, according to the present invention, the corrosion-resistant member is formed such that MgO is in a range of 15% by weight or more and Al 2 O 3 is 85% by weight or less in terms of oxide, and MgO, MgAl 2 O 4 and MgO, MgAl 2 A ceramic sintered body composed of any one of O 4 , MgAl 2 O 4 and Al 2 O 3 and having an average crystal particle diameter of 15 μm or more and a porosity of 0.1 % or less. Due to its formation, it has excellent corrosion resistance even when exposed to plasma in an atmosphere in which a halogen-based corrosive gas such as a fluorine-based or chlorine-based gas is present. It can be suitably used as a member such as a jig such as a ring or an inner wall material, or a protective tube for plasma generation used in a CFC decomposition apparatus or an excimer laser.
Claims (1)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14268097A JP3559426B2 (en) | 1997-05-30 | 1997-05-30 | Corrosion resistant materials |
| US09/031,401 US6447937B1 (en) | 1997-02-26 | 1998-02-26 | Ceramic materials resistant to halogen plasma and components using the same |
| US10/198,675 US6916559B2 (en) | 1997-02-26 | 2002-07-17 | Ceramic material resistant to halogen plasma and member utilizing the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14268097A JP3559426B2 (en) | 1997-05-30 | 1997-05-30 | Corrosion resistant materials |
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| JP3559426B2 true JP3559426B2 (en) | 2004-09-02 |
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