JP4261631B2 - Manufacturing method of ceramic sintered body - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、真空装置構造体、サセプタ、静電チャック、真空チャックまたはステッパーなどの半導体製造プロセスにおける製造装置用部材に適したコージェライトを主体とするセラミック焼結体の製造方法に関する。
【０００２】
【従来技術】
従来より、コージェライト系焼結体は、低熱膨張のセラミックスとして知られており、フィルター、ハニカム、耐火物などに応用されている。このコージェライト系焼結体は、特公昭５７−３６２９号、特開平２−２２９７６０号等に記載されるように、コージェライト粉末、あるいはコージェライトを形成するＭｇＯ、Ａｌ2 Ｏ3 、ＳｉＯ2 粉末を配合して、これに焼結助剤として、希土類元素酸化物や、ＳｉＯ2 、ＣａＯ、ＭｇＯなどを添加し、所定形状に成形後、１０００℃〜１４００℃の温度で焼結することによって作製されている。
【０００３】
一方、ＬＳＩなどの半導体の製造工程において、シリコンウエハに配線を形成する工程において、ウエハを支持または保持するためのサセプタ、静電チャックや絶縁リング、シリコンウエハへの回路形成のための露光装置のＸＹテーブル、あるいはその他の各種半導体製造装置用の治具として、これまでに主にアルミナや窒化珪素などのセラミックスが比較的に安価で、化学的にも安定であるため広く用いられている。
【０００４】
また最近では、コージェライトの低熱膨張性を利用し、コージェライト系焼結体を半導体製造装置部品として応用することが、特開平１−１９１４２２号や、特公平６−９７６７５号に提案されている。特開平１−１９１４２２号によれば、Ｘ線マスクにおけるマスク基板に接着する補強リングとして、ＳｉＯ2 、インバーなどに加え、コージェライトによって形成し、メンブレンの応力を制御することが提案されている。また、特公平６−９７６７５号では、ウエハを載置する静電チャック用基板としてアルミナやコージェライト系焼結体を使用することが提案されている。
【０００５】
【発明が解決しようとする課題】
近年、ＬＳＩなどにおける高集積化にともない、回路の微細化が急速に進められ、その回路の線幅もサブミクロンオーダーのレベルまで高集積化しつつある。そして、シリコンウエハに高精密回路を形成するための露光装置に対して高い精度が要求され、例えば露光装置のステージ用部材においては１００ｎｍ（０．１μｍ）以下の位置決め精度が要求され、露光の位置合わせ誤差が製品の品質向上や歩留まり向上に大きな影響を及ぼしているのが現状である。
【０００６】
半導体製造装置用として一般に用いられてきたアルミナ、窒化珪素などのセラミックスは、金属に比べて熱膨張率は小さいものの、１０〜４０℃の熱膨張率はそれぞれ、５．２×１０-6／℃、１．５×１０-6／℃であり、雰囲気温度が０．１℃変化すると数１００ｎｍ（０．１μｍ）の変形が発生することになり、露光等の精密な工程ではこの変化が大きな問題となり、従来のセラミックスでは精度が低く、生産性の低下をもたらしている。
【０００７】
これに対して、コージェライト系焼結体は、熱膨張率が０．２×１０-6／℃程度と、アルミナや窒化珪素に比較して熱膨張率が低く、上記のような露光精度に対する問題はある程度解決される。
【０００８】
ところが、露光装置用ステージのように、シリコンウエハを載置した支持体が露光処理を施す位置まで高速移動を伴うような場合には、移動後の支持体自体が所定位置に停止後も振動しており、そのために、その振動した状態で露光処理を施すと露光精度が低下するという問題があった。これは露光によって形成する配線が細くなるほど顕著であり、高精密な配線回路を形成する上では致命的な問題となっていた。
【０００９】
このような振動は、部材自体の剛性が低いことによって引き起こされるものであることから、これらの部材に対しては高い剛性、即ち高ヤング率が要求されている。
【００１０】
従って、本発明は、低熱膨張性とともに高ヤング率を有するセラミック焼結体の製造方法を提供することを目的とするものである。
【００１１】
また、本発明は、高集積回路素子などの半導体素子を製造するための装置に適用され、精密な配線回路を精度よく製造することのできる半導体製造装置用部材に適したセラミック焼結体の製造方法を提供することを目的とするものである。
【００１２】
【問題点を解決するための手段】
本発明者等は、上記問題点に対し、鋭意研究を重ねた結果、コージェライト結晶相を主体とするセラミック焼結体中において、コージェライト結晶中に、コージェライトの化学量論組成（２ＭｇＯ・２Ａｌ2 Ｏ3 ・５ＳｉＯ2 ）で表される組成よりもＭｇＯおよびＡｌ2 Ｏ3 を過剰に固溶させることにより、低熱膨張率化とともにヤング率を高めることができることを知見し、本発明に至った。
【００１５】
即ち、本発明のセラミック焼結体を製造する方法として、コージェライト粉末６９〜９７重量％に、ＭｇＯが０．５〜１０重量％およびＡｌ2Ｏ3 が１〜１５重量％の割合となるように添加混合した成形体を、１０００〜１２００℃の温度で１〜１０時間保持して、前記ＭｇＯおよび前記Ａｌ2Ｏ3をコージェライト結晶中に固溶させた後、１２００〜１５００℃の温度で焼成して緻密化することを特徴とするものである。
【００１６】
本発明の製造方法によれば、コージェライト結晶相を主相とし、その主相中に、化学量論組成（２ＭｇＯ・２Ａｌ2 Ｏ3 ・５ＳｉＯ2 ）よりも過剰のＭｇＯおよびＡｌ2 Ｏ3 を固溶させることにより、焼結性を改善できる上、高ヤング率、低熱膨張性を有するセラミック焼結体を得ることができる。
【００１７】
また、かかる焼結体中に、希土類元素化合物を上記の比率で添加含有せしめることにより、焼結性を改善し、さらに高ヤング率の窒化珪素、炭化珪素、酸窒化珪素を添加含有せしめることにより、さらなる低熱膨張性を損なうことなく、高ヤング率化を達成することができる。
【００１８】
【発明の実施の形態】
本発明の製造方法により得られるセラミック焼結体は、基本的に、ＭｇＯ、Ａｌ2Ｏ3
、ＳｉＯ2を構成成分とするコージェライト結晶相を主体とするものであるが、このコージェライト結晶相中には、コージェライトの化学量論組成比である２ＭｇＯ・２Ａｌ2Ｏ3・５ＳｉＯ2よりも、ＭｇＯおよびＡｌ2Ｏ3が過剰に存在することが大きな特徴である。ＭｇＯおよびＡｌ2Ｏ3が過剰に存在するとは、コージェライト結晶中のＭｇＯ：Ａｌ2Ｏ3：ＳｉＯ2比が２＋α：２＋β：５の組成（α＞０、β＞０）の意である。このように、コージェライト結晶中に、ＭｇＯおよびＡｌ2Ｏ3が過剰に存在することによって、焼結体の低熱膨張化と同時にヤング率を向上させることができる。
【００１９】
この理由は定かではないが、ＭｇＯおよびＡｌ2 Ｏ3 の固溶によって、結晶内に格子欠陥が形成され、それによって結晶粒子内に圧縮応力が発生しているためと推察される。なお、このコージェライト結晶相は、平均粒径が１〜１０μｍの結晶粒子として存在することが望ましい。
【００２０】
また、上記コージェライト結晶相中へのＭｇＯ、Ａｌ2 Ｏ3 の固溶に伴い、焼結体全体組成において、焼結体中の全ＳｉＯ2 がすべてコージェライト結晶相を構成することを前提として、過剰のＭｇＯおよびＡｌ2 Ｏ3 を、ＭｇＯとして０．５〜１０重量％、特に２〜７重量％、Ａｌ2 Ｏ3 として１〜１５重量％、特に５〜１０重量％の割合で含有する。
【００２１】
これら過剰のＭｇＯおよびＡｌ2 Ｏ3 は、焼成時には焼結性を高める作用をなし、最終的には、すべてコージェライト結晶相中に固溶してもよいが、結晶中への固溶限界を超える量で存在する場合には、その余剰分は、コージェライト結晶の粒界にガラス相あるいは結晶相として存在する。特に、ヤング率を高める観点から、上記の余剰のＭｇＯ、Ａｌ2 Ｏ3 は、スピネル結晶相として存在させることが望ましい。
【００２２】
過剰のＭｇＯおよびＡｌ2 Ｏ3 量を上記の範囲に限定したのは、ＭｇＯ量およびＡｌ2 Ｏ3 量が上記範囲よりも少ないと、焼結性の改善、高ヤング率、低熱膨張化の効果が期待できず、また上記範囲よりも多いと、熱膨張率が大きくなりすぎ、本発明の目的に適さないためである。
【００２３】
コージェライト結晶中へのＭｇＯおよびＡｌ2 Ｏ3 の固溶量α、βは、過剰に添加するＭｇＯおよびＡｌ2 Ｏ3 量や、焼成条件によっても変化するが、望ましくは、α≧０．０５、β≧０．０５であることがヤング率を高める上で望ましい。なお、固溶量の上限は、特に定める必要はなく、その焼成条件等によって決定される最大固溶限界まで固溶させてよい。
【００２４】
また、この焼結体中には、焼結性の改善のために、Ｙ、Ｙｂ、Ｅｒ、Ｌｕ、Ｓｍ、Ｃｅ、Ｄｙ等の希土類元素の酸化物を含有することが望ましい。希土類元素は、酸化物換算で２０重量％以下、特に１〜１０重量％の割合で含有することが望ましい。この希土類元素は、焼結体中のコージェライト結晶粒子の粒界にガラス相もしくは結晶相として存在し、特にシリケート結晶相として存在することがヤング率を高める上で望ましい。
【００２５】
さらに、この焼結体中には、窒化珪素、炭化珪素、酸窒化珪素の中から選ばれる少なくとも１種の結晶相を３０重量％以下、特に５〜２０重量％の割合で分散せしめることによりヤング率をさらに向上させることができる。これらの中でも窒化珪素が最も効果的である。なお、酸窒化珪素とは、Ｓｉ−Ｎ−Ｏ系化合物であり、例えばＳｉ2 Ｎ2 Ｏである。これらの成分が３０重量％を超えると、焼結体の熱膨張率が高くなりすぎてしまう。
【００２６】
本発明の製造方法により得られるセラミック焼結体は、上記のような構成に基づき、室温での熱膨張率が０．５×１０-6／℃以下、特に０．３×１０-6／℃以下、ヤング率が１３０ＧＰａ以上、特に１５０ＧＰａ以上の特性を具備することが大きな特徴であり、このような特性を得る上で、焼結体の相対密度が９５％以上、相対密度が９５％以上、特に９７％以上の高緻密体からなることも必要であり、相対密度が９５％よりも低いと、前記コージェライト結晶中にＭｇＯ、Ａｌ2Ｏ3が過剰に固溶しても上記のような低熱膨張性と高ヤング率を達成することができない。
【００２７】
次に、本発明における上記セラミック焼結体を作製する方法について説明すると、まず、平均粒径が１０μｍ以下のコージェライト粉末に対して、ＭｇＯを０．５〜１０重量％、特に２〜７重量％、Ａｌ2 Ｏ3 を１〜１５重量％、特に５〜１０重量％の割合で添加混合する。また、場合によっては、希土類元素酸化物を２０重量％以下、特に１０重量％以下、さらには、平均粒径が１０μｍ以下の窒化珪素、炭化珪素、酸窒化珪素粉末を３０重量％以下の割合で添加混合する。
【００２８】
前記ＭｇＯ、Ａｌ2 Ｏ3 、希土類元素酸化物等は、酸化物の他に、水酸化物、炭酸塩、硝酸塩、酢酸塩などのように焼成によって酸化物を形成し得る化合物の形態で添加することも可能である。
【００２９】
上記の比率で各成分を配合した後、ボールミルなどにより十分に混合し、所定形状に所望の成形手段、例えば、金型プレス，冷間静水圧プレス，押出し成形等により任意の形状に成形後、焼成する。
【００３０】
焼成は、まず、成形体を１０００〜１２００℃の温度範囲で１〜１０時間保持して前処理した後、昇温して１２００〜１５００℃、特に１３００〜１４００℃の温度範囲で１〜１０時間本焼成して相対密度９５％以上に緻密化を図る。なお、本焼成時の温度が１２００℃よりも低いと相対密度９５％以上に緻密化することが難しく、１５００℃を越えると、成形体が溶融してしまうためである。
【００３１】
上記のように、本焼成に先立って、本焼成時の温度よりも低い温度で一旦保持することによって、ＭｇＯおよびＡｌ2 Ｏ3 の主結晶相への固溶を促進することができる。なお、ＭｇＯおよびＡｌ2 Ｏ3 量が固溶限界量を超えて含有される場合、余剰のＭｇＯおよびＡｌ2 Ｏ3 は、スピネル相として粒界相に析出させることによって、非晶質相として残存するよりもヤング率が向上する点で望ましい。スピネル相としての析出を促進するために、焼成後の８００℃までの冷却速度を１００℃／ｈｒ以下とすることが望ましい。
【００３２】
焼成時の雰囲気は、大気などの酸化性雰囲気、真空もしくはＡｒ、Ｎ2 などの不活性ガス雰囲気等のいずれでもよいが、成形体中に窒化珪素、炭化珪素、酸窒化珪素等を含む場合は、酸化性雰囲気中で焼成するとこれらの成分が酸化されてしまいヤング率を高める効果が発揮されなくなるために、真空もしくはＡｒ、Ｎ2 などの不活性ガス雰囲気中で焼成することが必要である。
【００３３】
また、本発明の製造方法により得られるセラミック焼結体は、低熱膨張特性と高ヤング率を有することから、各種産業機械部品として用いることができるが、特に、ＩＣ素子などの半導体素子を製造するための装置、具体的には、真空装置を形成する構造部材、真空装置内にて半導体ウエハを固定支持するサセプタ、静電チャック、真空チャックなど、さらには回路形成のための露光装置における光学系の各種支持部材あるいは装置の構造部材や、ウエハを支持するＸＹステージのステッパーなどに適用することにより、半導体素子製造時の上記部材の熱膨張による精度の低下、あるいは外的、あるいは内的な要因による装置や部材の振動を低減することができる結果、高精度で歩留りの高い半導体素子の製造を実現することができる。
【００３４】
【実施例】
ＢＥＴ比表面積が３ｍ2 ／ｇのコージェライト粉末に対して、平均粒径が１μｍ以下のＭｇ（ＯＨ）2 、Ａｌ2 Ｏ3 粉末、平均粒径が１μｍの窒化珪素粉末、炭化珪素粉末、酸窒化珪素（Ｓｉ2 Ｎ2 Ｏ，表中ではＳＮＯと記載した。）、さらに、焼結助剤成分として、Ｙ2 Ｏ3 、Ｙｂ2 Ｏ3 、Ｅｒ2 Ｏ3 、ＣｅＯ2 の各粉末を表１乃至表２に示す割合で調合後、ボールミルで２４時間混合した後、１ｔ／ｃｍ2 の圧力で金型成形した。そして、その成形体を炭化珪素質の匣鉢に入れて表１、表２の条件で前焼成、本焼成を行なった。
【００３５】
得られた焼結体を研磨し、３×４×１５ｍｍの大きさに研削加工し、この試料の相対密度をアルキメデス法に従って算出した。また、１０〜４０℃までの熱膨張係数、および超音波パルス法により室温でのヤング率を測定した。また、焼結体のＸ線回折測定によって焼結体を構成する結晶相を同定した。結果は、表１乃至表２に示した。
【００３６】
【表１】
【表２】
表１、表２の結果から明らかなように、前焼成を施さない試料Ｎo.７，９，１４では、ＭｇＯおよびＡｌ2 Ｏ3 を固溶させないもしくは固溶量の少ないＮｏ．１〜４はヤング率が低い。また、ＭｇＯおよび／またはＡｌ2 Ｏ3 を固溶量が多い試料Ｎo.１２、希土類酸化物量の多い試料Ｎo.２０、窒化珪素量の多い試料Ｎo.２７は熱膨張率が高い。
【００３９】
焼成温度が本発明の範囲外である試料Ｎo.２８、３１は溶解したり、緻密体が得られない。これらの比較例に対して、その他の本発明に基づく試料は、いずれも熱膨張率が０．５×１０-6／℃以下、ヤング率が１３０ＧＰａ以上と優れた特性を有していた。
【００４０】
【発明の効果】
以上詳述した通り、本発明によれば、コージェライト結晶中にＭｇＯおよびＡｌ2 Ｏ3 を固溶させることにより、低熱膨張化とともに、高ヤング率化を図ることができる結果、かかる焼結体を半導体素子製造装置用部品として用いることにより、高精度で歩留りのよい半導体素子の製造を実現することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention is a vacuum device structure, a susceptor, an electrostatic chuck, about the manufacturing how a ceramic sintered body composed mainly of cordierite which are suitable for members for the manufacturing apparatus in the semiconductor manufacturing process such as a vacuum chuck or a stepper.
[0002]
[Prior art]
Conventionally, cordierite-based sintered bodies are known as low thermal expansion ceramics and are applied to filters, honeycombs, refractories, and the like. This cordierite-based sintered body is made of cordierite powder or MgO, Al 2 O 3 , SiO 2 powder forming cordierite as described in Japanese Patent Publication No. 57-3629, JP-A-2-229760, etc. It is prepared by adding rare earth element oxide, SiO 2 , CaO, MgO or the like as a sintering aid to this, forming into a predetermined shape, and sintering at a temperature of 1000 ° C. to 1400 ° C. Has been.
[0003]
On the other hand, in the manufacturing process of semiconductors such as LSI, in the process of forming wiring on a silicon wafer, a susceptor for supporting or holding the wafer, an electrostatic chuck or an insulating ring, and an exposure apparatus for forming a circuit on the silicon wafer. As jigs for XY tables or other various semiconductor manufacturing apparatuses, ceramics such as alumina and silicon nitride have been widely used so far because they are relatively inexpensive and chemically stable.
[0004]
Recently, it has been proposed in Japanese Patent Application Laid-Open No. 1-191422 and Japanese Patent Publication No. 6-97675 to apply cordierite-based sintered bodies as semiconductor manufacturing device parts by utilizing the low thermal expansion property of cordierite. . According to Japanese Patent Laid-Open No. 1-191422, it is proposed that a reinforcing ring that adheres to a mask substrate in an X-ray mask is formed of cordierite in addition to SiO 2 or invar to control the stress of the membrane. Japanese Patent Publication No. 6-97675 proposes the use of alumina or a cordierite-based sintered body as an electrostatic chuck substrate on which a wafer is placed.
[0005]
[Problems to be solved by the invention]
In recent years, along with high integration in LSI and the like, circuit miniaturization has been rapidly advanced, and the line width of the circuit is being highly integrated to a submicron order level. Further, high accuracy is required for an exposure apparatus for forming a high-precision circuit on a silicon wafer. For example, a stage member of the exposure apparatus requires positioning accuracy of 100 nm (0.1 μm) or less, and the position of exposure. At present, the alignment error has a great influence on the improvement of product quality and yield.
[0006]
Although ceramics such as alumina and silicon nitride that have been generally used for semiconductor manufacturing equipment have a smaller coefficient of thermal expansion than metals, the coefficient of thermal expansion at 10 to 40 ° C. is 5.2 × 10 −6 / ° C., respectively. 1.5 × 10 −6 / ° C. When the atmospheric temperature changes by 0.1 ° C., deformation of several hundred nm (0.1 μm) occurs, and this change is a big problem in precise processes such as exposure. Therefore, conventional ceramics have low accuracy, resulting in a decrease in productivity.
[0007]
On the other hand, the cordierite-based sintered body has a thermal expansion coefficient of about 0.2 × 10 −6 / ° C., which is lower than that of alumina or silicon nitride. The problem is solved to some extent.
[0008]
However, when the support on which the silicon wafer is placed is moved to a position where exposure processing is performed at a high speed, such as the stage for an exposure apparatus, the moved support itself vibrates even after stopping at a predetermined position. For this reason, there has been a problem in that the exposure accuracy is lowered when the exposure process is performed in the vibrated state. This becomes more conspicuous as the wiring formed by exposure becomes thinner, and has become a fatal problem in forming a highly precise wiring circuit.
[0009]
Since such vibration is caused by the low rigidity of the members themselves, high rigidity, that is, high Young's modulus is required for these members.
[0010]
Accordingly, an object of the present invention is to provide a method for producing a ceramic sintered body having low thermal expansion and high Young's modulus.
[0011]
In addition, the present invention is applied to an apparatus for manufacturing a semiconductor element such as a highly integrated circuit element, and a ceramic sintered body suitable for a member for a semiconductor manufacturing apparatus capable of accurately manufacturing a precise wiring circuit. It is intended to provide a method .
[0012]
[Means for solving problems]
As a result of intensive studies on the above problems, the present inventors have found that in the ceramic sintered body mainly composed of the cordierite crystal phase, the cordierite crystal has a stoichiometric composition (2MgO · 2Al 2 O 3 · 5SiO 2 ) It was found that MgO and Al 2 O 3 can be excessively solid-solved than the composition represented by 2Al 2 O 3. It was.
[0015]
That is, as a method for producing a ceramic sintered body of the present invention, the cordierite powder 69-97% by weight, so that the MgO is 0.5 to 10 wt% and Al 2 O 3 at a ratio of 1-15 wt% The molded body added and mixed in is held at a temperature of 1000 to 1200 ° C. for 1 to 10 hours to dissolve the MgO and the Al 2 O 3 in cordierite crystals, and then at a temperature of 1200 to 1500 ° C. It is characterized by being densified by firing.
[0016]
According to the production method of the present invention , a cordierite crystal phase is a main phase, and MgO and Al 2 O 3 in excess of the stoichiometric composition (2MgO · 2Al 2 O 3 · 5SiO 2 ) are contained in the main phase. By solid solution, it is possible to improve the sinterability and obtain a ceramic sintered body having high Young's modulus and low thermal expansion.
[0017]
In addition, by adding a rare earth element compound in the above ratio to the sintered body, the sinterability is improved, and by further adding silicon nitride, silicon carbide, silicon oxynitride having a high Young's modulus. A higher Young's modulus can be achieved without impairing the further low thermal expansion.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The ceramic sintered body obtained by the production method of the present invention is basically composed of MgO, Al 2 O 3.
The cordierite crystal phase mainly composed of SiO 2 is mainly composed of 2MgO · 2Al 2 O 3 · 5SiO 2 , which is the stoichiometric composition ratio of cordierite. Is also characterized by the excessive presence of MgO and Al 2 O 3 . Existence of MgO and Al 2 O 3 means a composition (α> 0, β> 0) in which the ratio of MgO: Al 2 O 3 : SiO 2 in the cordierite crystal is 2 + α: 2 + β: 5. Thus, the presence of excessive MgO and Al 2 O 3 in the cordierite crystal makes it possible to improve the Young's modulus at the same time as lowering the thermal expansion of the sintered body.
[0019]
The reason for this is not clear, but it is presumed that lattice defects are formed in the crystal due to the solid solution of MgO and Al 2 O 3 , thereby generating a compressive stress in the crystal grains. The cordierite crystal phase is preferably present as crystal particles having an average particle diameter of 1 to 10 μm.
[0020]
In addition, with the solid solution of MgO and Al 2 O 3 in the above cordierite crystal phase, in the overall composition of the sintered body, it is assumed that all SiO 2 in the sintered body constitutes the cordierite crystal phase. And excess MgO and Al 2 O 3 in a proportion of 0.5 to 10% by weight, especially 2 to 7% by weight as MgO, and 1 to 15% by weight, in particular 5 to 10% by weight, as Al 2 O 3 .
[0021]
These excess MgO and Al 2 O 3 have the effect of enhancing the sinterability during firing, and eventually all may be dissolved in the cordierite crystal phase, but the solid solution limit in the crystal is limited. When it exists in the quantity exceeding, the surplus exists in the grain boundary of a cordierite crystal as a glass phase or a crystal phase. In particular, from the viewpoint of increasing the Young's modulus, it is desirable that the excess MgO and Al 2 O 3 be present as a spinel crystal phase.
[0022]
Excessive MgO and Al 2 O 3 amounts were limited to the above ranges because, if the MgO amount and Al 2 O 3 amount are less than the above ranges, the effect of improving sinterability, high Young's modulus, and low thermal expansion This is because the thermal expansion coefficient is too large and is not suitable for the purpose of the present invention.
[0023]
The solid solution amounts α and β of MgO and Al 2 O 3 in the cordierite crystal vary depending on the amount of MgO and Al 2 O 3 added excessively and the firing conditions, but preferably α ≧ 0.05. Β ≧ 0.05 is desirable for increasing the Young's modulus. Note that the upper limit of the solid solution amount is not particularly required, and the solid solution may be dissolved up to the maximum solid solution limit determined by the firing conditions and the like.
[0024]
Further, it is desirable that the sintered body contains an oxide of a rare earth element such as Y, Yb, Er, Lu, Sm, Ce, or Dy in order to improve the sinterability. The rare earth element is preferably contained in an amount of 20% by weight or less, particularly 1 to 10% by weight in terms of oxide. This rare earth element is present as a glass phase or a crystal phase at the grain boundary of the cordierite crystal particles in the sintered body, and in particular, it is desirable to exist as a silicate crystal phase in order to increase the Young's modulus.
[0025]
Further, in this sintered body, at least one crystal phase selected from silicon nitride, silicon carbide, and silicon oxynitride is dispersed in a proportion of 30% by weight or less, particularly 5 to 20% by weight. The rate can be further improved. Of these, silicon nitride is the most effective. Silicon oxynitride is a Si—N—O-based compound, for example, Si 2 N 2 O. When these components exceed 30% by weight, the thermal expansion coefficient of the sintered body becomes too high.
[0026]
The ceramic sintered body obtained by the production method of the present invention has a thermal expansion coefficient at room temperature of 0.5 × 10 −6 / ° C. or less, particularly 0.3 × 10 −6 / ° C., based on the above configuration. Hereinafter, the Young's modulus is 130 GPa or more, particularly having a characteristic of 150 GPa or more. In obtaining such characteristics, the sintered body has a relative density of 95% or more, a relative density of 95% or more, In particular, it is also necessary to be composed of a highly dense body of 97% or more. If the relative density is lower than 95%, the above cordierite crystal may contain MgO and Al 2 O 3 in excessive solid solution as described above. Low thermal expansion and high Young's modulus cannot be achieved.
[0027]
Next, a method for producing the ceramic sintered body according to the present invention will be described. First, MgO is 0.5 to 10% by weight, particularly 2 to 7% by weight with respect to cordierite powder having an average particle size of 10 μm or less. %, Al 2 O 3 in an amount of 1 to 15% by weight, particularly 5 to 10% by weight. In some cases, the rare earth element oxide is 20 wt% or less, particularly 10 wt% or less, and the silicon nitride, silicon carbide, or silicon oxynitride powder having an average particle size of 10 μm or less is 30 wt% or less. Add and mix.
[0028]
The MgO, Al 2 O 3 , rare earth element oxide and the like are added in the form of a compound capable of forming an oxide by firing such as hydroxide, carbonate, nitrate, acetate, etc. in addition to the oxide. It is also possible.
[0029]
After blending each component in the above ratio, mix well with a ball mill or the like, and after molding into a desired shape by a desired molding means such as a die press, cold isostatic pressing, extrusion molding, etc., Bake.
[0030]
In the firing, the molded body is first pretreated by holding in a temperature range of 1000 to 1200 ° C. for 1 to 10 hours, and then heated to 1200 to 1500 ° C., particularly 1300 to 1400 ° C. for 1 to 10 hours. This is fired to increase the density to 95% or higher relative density. This is because if the temperature during the main firing is lower than 1200 ° C., it is difficult to densify to a relative density of 95% or more, and if it exceeds 1500 ° C., the molded body is melted.
[0031]
As described above, prior to the main baking, the solid solution of MgO and Al 2 O 3 in the main crystal phase can be promoted by temporarily holding at a temperature lower than the temperature during the main baking. When the amount of MgO and Al 2 O 3 exceeds the solid solution limit, excess MgO and Al 2 O 3 remain as an amorphous phase by being precipitated in the grain boundary phase as a spinel phase. It is desirable in that the Young's modulus improves rather than. In order to promote precipitation as a spinel phase, it is desirable that the cooling rate to 800 ° C. after firing is 100 ° C./hr or less.
[0032]
The atmosphere during firing may be any of an oxidizing atmosphere such as air, a vacuum or an inert gas atmosphere such as Ar, N 2, etc., but if the molded body contains silicon nitride, silicon carbide, silicon oxynitride, etc. When fired in an oxidizing atmosphere, these components are oxidized and the effect of increasing the Young's modulus is not exhibited. Therefore, it is necessary to fire in an inert gas atmosphere such as vacuum or Ar, N 2 .
[0033]
In addition, the ceramic sintered body obtained by the production method of the present invention has low thermal expansion characteristics and high Young's modulus, and therefore can be used as various industrial machine parts. In particular, it produces semiconductor elements such as IC elements. Apparatus, specifically a structural member for forming a vacuum device, a susceptor for fixing and supporting a semiconductor wafer in the vacuum device, an electrostatic chuck, a vacuum chuck, etc., and an optical system in an exposure apparatus for circuit formation When applied to various support members of the above, structural members of the apparatus, stepper of the XY stage that supports the wafer, etc., the deterioration of accuracy due to thermal expansion of the above members at the time of semiconductor element manufacture, or external or internal factors As a result, it is possible to reduce the vibrations of the devices and members due to the above, and to realize the manufacture of semiconductor elements with high accuracy and high yield.
[0034]
【Example】
For cordierite powder having a BET specific surface area of 3 m 2 / g, Mg (OH) 2 , Al 2 O 3 powder having an average particle diameter of 1 μm or less, silicon nitride powder having an average particle diameter of 1 μm, silicon carbide powder, acid Silicon nitride (Si 2 N 2 O, indicated as SNO in the table), and Y 2 O 3 , Yb 2 O 3 , Er 2 O 3 , and CeO 2 powders as sintering aid components are shown. After blending at the ratios shown in 1 to Table 2, the mixture was mixed with a ball mill for 24 hours, and then molded at a pressure of 1 t / cm 2 . Then, the compact was put in a silicon carbide bowl and pre-fired and main-fired under the conditions shown in Tables 1 and 2.
[0035]
The obtained sintered body was polished and ground to a size of 3 × 4 × 15 mm, and the relative density of this sample was calculated according to the Archimedes method. Further, the coefficient of thermal expansion up to 10 to 40 ° C. and the Young's modulus at room temperature were measured by an ultrasonic pulse method. The crystal phase constituting the sintered body was identified by X-ray diffraction measurement of the sintered body. The results are shown in Tables 1 and 2.
[0036]
[Table 1]
[Table 2]
As is apparent from the results of Tables 1 and 2, Samples Nos. 7, 9, and 14 that were not pre-fired did not cause MgO and Al 2 O 3 to be dissolved in a solid solution or had a small solid solution amount. 1-4 has a low Young's modulus. Further, Sample No. 12 with a large amount of MgO and / or Al 2 O 3 , Sample No. 20 with a large amount of rare earth oxide, and Sample No. 27 with a large amount of silicon nitride have a high coefficient of thermal expansion.
[0039]
Samples No. 28 and 31 whose firing temperature is outside the range of the present invention are not dissolved or a dense body cannot be obtained. In contrast to these comparative examples, all other samples according to the present invention had excellent characteristics such as a coefficient of thermal expansion of 0.5 × 10 −6 / ° C. or less and a Young's modulus of 130 GPa or more.
[0040]
【The invention's effect】
As described above in detail, according to the present invention, MgO and Al 2 O 3 are solid-dissolved in the cordierite crystal, so that a low Young's modulus can be achieved as well as a low thermal expansion. Can be used as a component for a semiconductor device manufacturing apparatus, so that it is possible to manufacture a semiconductor device with high accuracy and good yield.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| JP05946098A JP4261631B2 (en) | 1998-03-11 | 1998-03-11 | Manufacturing method of ceramic sintered body |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| JP05946098A JP4261631B2 (en) | 1998-03-11 | 1998-03-11 | Manufacturing method of ceramic sintered body |
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| JPH11255557A JPH11255557A (en) | 1999-09-21 |
| JP4261631B2 true JP4261631B2 (en) | 2009-04-30 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108495829A (en) * | 2016-01-27 | 2018-09-04 | 住友大阪水泥股份有限公司 | Ceramic material and electrostatic chuck apparatus |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001058867A (en) * | 1999-08-23 | 2001-03-06 | Taiheiyo Cement Corp | Structure part |
| JP2002173366A (en) * | 2000-12-06 | 2002-06-21 | Nippon Tungsten Co Ltd | Cordierite based ceramic material |
| JP4912544B2 (en) * | 2001-07-11 | 2012-04-11 | 太平洋セメント株式会社 | Low thermal conductivity high rigidity ceramics |
| JP5164304B2 (en) * | 2001-08-22 | 2013-03-21 | 京セラ株式会社 | Manufacturing method of ceramics |
| JP2003137644A (en) * | 2001-11-05 | 2003-05-14 | Nippon Tungsten Co Ltd | Low thermal expansion ceramic, members for ultra- precise machine structure, measuring instrument and semiconductor manufacturing equipment using the same, and method of producing low thermal expansion ceramic |
| US6736875B2 (en) * | 2001-12-13 | 2004-05-18 | Corning Incorporated | Composite cordierite filters |
| JP2007137764A (en) * | 2006-11-29 | 2007-06-07 | Kyocera Corp | Dielectric ceramic composition, and dielectric resonator, nonradioactive dielectric line and high frequency wiring board using the same |
| JP5657210B2 (en) * | 2009-01-28 | 2015-01-21 | 京セラ株式会社 | A member for semiconductor manufacturing equipment comprising a cordierite sintered body |
| ES2362533B1 (en) * | 2009-12-21 | 2012-05-17 | Consejo Superior De Investigaciones Cientificas (Csic) | COMPOSITE MATERIAL WITH THERMAL EXPANSION COEFFICIENT CONTROLLED WITH OXIDIC MICAS CERAMICS AND THEIR OBTAINING PROCEDURE. |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108495829A (en) * | 2016-01-27 | 2018-09-04 | 住友大阪水泥股份有限公司 | Ceramic material and electrostatic chuck apparatus |
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