JP2004296522A - Method of forming thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming thin film by which a ferroelectric film can be formed by the MOCVD method by minimizing the occurrence of particles. <P>SOLUTION: The temperature rising rate of an organic metallic material in a vaporizing step is increased by using some of 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, ethyl formate, methyl acetate, and n-propylamine having a thermal capacity per unit volume of ≤56.5 J/ml as an organic solvent which dissolves the organic metallic material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

表１を参照するに、溶媒としてＴＨＦを使った場合には、得られたＰＺＴ膜の膜厚が１２０ｎｍで膜中のＰｂ組成が１．１６、Ｚｒ組成が０．４２であるのに対し、溶媒として酢酸ブチルを使った場合、ほぼ同様な１１４ｎｍの膜厚を有しほぼ同様な１．１７のＰｂ組成と０．４５のＺｒ組成を有するＰＺＴ膜が得られているのがわかる。一方、溶媒として酢酸ブチルを使った場合には、先にも述べたように基板上のパーティクル数が、溶媒としてＴＨＦを使った場合に比べて大きく増大する。
【００２９】
このように、使われた溶媒により膜中に含まれるパーティクル数が異なる理由は、おそらく気化器１２中において溶媒の熱容量の差により昇温速度に差が生じ、特に大きな熱容量を有する溶媒を使った場合、液体原料の温度が所定の気化温度に達するまでに時間がかかるためと考えられる。
【００３０】
図２は、ＴＨＦ溶媒および酢酸ブチル溶媒を１．２ｍｌ／分の割合で前記気化器１２に給送した場合の、前記気化器１２において生じる溶媒の昇温カーブを示す。
【００３１】
図２を参照するに、熱容量が大きな酢酸ブチルを溶媒に使った場合、熱容量が小さなＴＨＦを溶媒に使った場合に比べて、所定の１９０℃の気化温度に達するまでの昇温時間が約３倍まで増大しているのがわかる。
【００３２】
図３は、様々な熱容量の有機溶媒を様々な流量で前記気化器１２に供給した場合における、溶媒の温度が所定の気化温度に達するまでの時間を示す。
【００３３】
図３を参照するに、有機溶媒の流量が一定の場合、溶媒の温度が前記所定の気化温度に達するまでの時間は、溶媒の熱容量が小さければ小さい程短く、また溶媒の流量が少なければ少ないほど短いことがわかる。
【００３４】
図１のＭＯＣＶＤ装置では、前記気化器１２に給送される液体原料の大部分、例えば９０〜９９％が溶媒であり、有機金属原料の熱容量の効果はほとんど無視することができる。そこで、溶媒の熱容量が大きい場合、液体原料の気化までに時間がかかり、その間に液体原料中に溶解している有機金属原料に部分的な分解や劣化が生じ、このように劣化した有機金属原料が処理容器１１中に導入されることにより、パーティクルの発生が生じるものと考えられる。前記有機金属原料は、図４に示すように金属原子を複数の配位子が取り囲んだ構造を有しており、これらの配位子の一または複数が脱離することにより、気化温度は大きく変化する。
【００３５】
図５は、上記の実験から求められた、液体原料中の溶媒の熱容量と、得られたＰＺＴ膜中のパーティクル数との関係を示す。
【００３６】
図５を参照するに、まず溶媒の単位体積あたり熱容量を５６．５Ｊ／ｍｌ未満に低減することにより、６インチ径の基板上において生じるパーティクルの数をほぼ２００個あるいはそれ以下とすることができるのがわかる。
【００３７】
さらに図５から、前記溶媒の単位体積あたり熱容量が約５０Ｊ／ｍｌ以下の場合、６インチ径の基板上のパーティクル数を約１５０個あるいはそれ以下に抑制することが可能になるのがわかる。また前記溶媒の単位体積あたり熱容量が約４０Ｊ／ｍｌ以下の場合、基板上のパーティクル数を約１００個あるいはそれ以下に抑制することが可能になるのがわかる。さらに前記有機溶媒の単位体積あたり熱容量が約３０Ｊ／ｍｌの場合、基板上のパーティクルの数を約５０個あるいはそれ以下に抑制することが可能になるのがわかる。
【００３８】
このように基板上のパーティクル数を、上記の実験の場合よりも減少できる溶媒としては、以下の表２にまとめて示すものを使うことができる。
【００３９】
【表２】

例えば、前記有機溶媒として熱容量が５１．５Ｊ／ｍｌの２−メチルペンタンを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２_１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約１６９個以下に抑制することが可能になる。
【００４０】
また、前記有機溶媒として熱容量が５５．９Ｊ／ｍｌの３−メチルペンタンを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２_１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約２４０個以下に抑制することが可能になる。
【００４１】
さらに、前記有機溶媒として熱容量が３５．８Ｊ／ｍｌの２，２−ジメチルブタンを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約４３個以下に抑制することが可能になる。
【００４２】
また前記有機溶媒として熱容量が４７．５Ｊ／ｍｌの２，３−ジメチルブタンを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２_１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約１４０個以下に抑制することが可能になる。
【００４３】
さらに、前記有機溶媒として熱容量が３２．５Ｊ／ｍｌのシクロペンタンを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２_１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約１７個以下に抑制することが可能になる。
【００４４】
さらに、前記有機溶媒として熱容量が３１．１Ｊ／ｍｌのメチラールを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２_１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約５個以下に抑制することが可能になる。
【００４５】
さらに、前記有機溶媒として熱容量が５１．６Ｊ／ｍｌのエチルホルメートを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約１７０個以下に抑制することが可能になる。
【００４６】
さらに、前記有機溶媒として熱容量が５６．４Ｊ／ｍｌのメチルアセテートを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２_１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約２０８個以下に抑制することが可能になる。
【００４７】
さらに、前記有機溶媒として熱容量が４５．９Ｊ／ｍｌのｎ−プロピルアミンを使い、この中にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_２およびＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解してＰｂ，ＺｒおよびＴｉの液体原料を作製した場合、このようにして作製された液体原料を、前記原料容器１２_１〜１２_３から前記気化器１２に合計流量が１．２ｍｌ／分になるように供給し、１９０℃の温度で気化させることにより、前記処理容器１１中に３００ＳＣＣＭの流量の窒素キャリアガスと共に供給し、さらに前記処理容器１１中に酸素ガスを２５００ＳＣＣＭの流量で供給し、５８０°の基板温度においてＰＺＴ膜を６インチ径の基板上に形成した場合に得られるＰＺＴ膜中に含まれる径が０．２μｍ以上のパーティクルの数を、約１２４個以下に抑制することが可能になる。
【００４８】
先にも述べたように、このような液体原料の昇温速度は主に有機溶媒の熱容量により決まるものであり、有機溶媒中に溶解される有機金属原料の種類には実質的に無関係である。また前記ＰＺＴ膜を形成した例ではＰｂの有機金属原料としてＰｂ（ＴＨＤ）_２を使い、Ｚｒの有機金属原料としてＺｒ（ＤＭＨＤ）_４を使い、Ｔｉの有機金属原料としてＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を使っているが、これらの化合物の気化温度はそれぞれ１８０〜２００℃，２５０〜２７０℃および２００〜２２０℃の範囲であり、従って上記のメカニズムによるパーティクル発生の抑制は、上記の原料系を使ったＰＺＴ膜の成膜工程に限定されるものではなく、同様な気化温度範囲、例えば１８０〜３００℃の範囲の気化温度を有する有機金属原料を使う場合においても有効であると考えられる。
【００４９】
また、上記の有機溶媒は、他の原料系を使って実行される他の膜、例えばＢＳＴ（ＢａＳｒＴｉＯ_３）膜やＳＢＴ（ＳｒＢｉ_２（Ｔａ，Ｎｂ）_２Ｏ_９）膜，ＢＬＴ（ＢｉＬａ）_４Ｔｉ_３Ｏ_１２膜，ＢＩＴ（Ｂｉ_４Ｔｉ_３Ｏ_１２）膜の形成の際にも有効であると考えられる。
【００５０】
例えばＢＳＴ膜を形成する場合には、前記単位体積あたりの熱容量が５６．５Ｊ／ｍｌ未満の有機溶媒中にＢａの有機金属原料としてＢａ（ＴＨＤ）_２を溶解して得られた液体原料と、前記有機溶媒中にＳｒの有機金属原料としてＳｒ（ＴＨＤ）_２を溶解して得られた液体原料と、さらにＴｉの有機金属原料として前記有機溶媒中にＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を溶解して得られた液体原料とを使うことが可能である。
【００５１】
またＳＢＴ膜を形成する場合には、前記有機溶媒中にＢｉの有機金属原料としてＢｉ（ｐｈ）_３を溶解して得られた液体原料と、前記有機溶媒中にＳｒの有機金属原料としてＳｒ（ＴＨＤ）_２を溶解して得られた液体原料と、Ｔａの有機金属原料として前記有機溶媒中にＴａ（Ｏ−ｉＰｒ）_４（ＴＨＤ）を溶解して得られた液体原料と、さらに前記有機溶媒中にＮｂの有機金属原料としてＮｂ（Ｏ−ｉＰｒ）_５を溶解して得られた液体原料とを使うことが可能である。
【００５２】
さらにＢＬＴ膜を形成する場合には、前記有機溶媒中にＢｉの有機金属原料としてＢｉ（ｐｈ）_３を溶解して得られた液体原料と、前記有機溶媒中にＬａの有機金属原料としてＬａ（ＴＨＤ）_３を溶解して得られた液体原料と、Ｔｉの有機金属原料として前記有機溶媒中にＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）を溶解して得られた液体原料とを使うことが可能である。
【００５３】
またＢＩＴ膜を形成する場合には、前記有機溶媒中にＢｉの有機金属原料としてＢｉ（ｐｈ）_３を溶解して得られた液体原料と、Ｔｉの有機金属原料として前記有機溶媒中にＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）を溶解して得られた液体原料とを使うことが可能である。
【００５４】
なお、Ｂｉの原料としては、Ｂｉ（ｐｈ）_３の他にＢｉ（ＴＨＤ）_３を使うことが可能である。またＴａの原料としては、Ｔａ（Ｏ−ｉＰｒ）_４（ＴＨＤ）の他にＴａ（ＯＥｔ）_５を使うことが可能である。
［第２実施例］
次に、図１のＭＯＣＶＤ装置１０を使った、本発明の第２実施例によるＦｅＲＡＭの製造工程を説明する。
【００５５】
図６は、本発明の第２実施例によるＦｅＲＡＭ３０の構成を示す。
【００５６】
図６を参照するに、ＦｅＲＡＭ３０は素子分離構造３０Ａにより画成された素子領域を有するＳｉ基板３１上に形成されており、前記Ｓｉ基板３１上には前記活性領域に対応して、ゲート絶縁膜３２を介して形成されたゲート電極３３と、前記ゲート電極３３の両側において前記Ｓｉ基板３１中に形成されたソースおよびドレイン拡散領域３１Ａ，３１Ｂとが形成されている。
【００５７】
さらに前記Ｓｉ基板３１上には、層間絶縁膜３４が形成されており、前記層間絶縁膜３４には、一方の拡散領域３１Ａに電気的に接続された導電性プラグ３４Ａが埋め込まれている。さらに層間絶縁膜３４上には前記プラグ３４Ａを介して前記拡散領域３１Ａに電気的に接続されたビット線ＢＬが形成されている。
【００５８】
前記ビット線ＢＬが形成された層間絶縁膜３４上には、更に層間絶縁膜３５が形成されており、前記層間絶縁膜３５には層間絶縁膜３４を貫通して他方の拡散領域３１Ｂに電気的に接続された導電性プラグ３５Ｂが埋め込まれている。
【００５９】
前記導電性プラグ３５Ｂが埋め込まれた層間絶縁膜３５上にはバリアメタル層と下部電極層を順次積層した構造を有する下部キャパシタ電極３６が形成されている。前記下部キャパシタ電極３６において下部電極層はＩｒ層あるいはＰｔ層より構成される。前記下部電極層としてＰｔ層を用いる場合には、バリアメタル層としてＩｒ層が形成され、前記Ｉｒ層上に密着層として例えばＩｒＯｘ層が形成される。Ｐｔ下部電極層は、このようにして形成されたＩｒＯｘ層上に形成される。一方、前記下部電極層をＩｒ層とする場合には、前記下部キャパシタ電極３６は単一のＩｒ層より構成される。図６は、前記下部キャパシタ電極３６として、Ｉｒ層を用いた場合を示している。
【００６０】
前記下部キャパシタ電極３６上には、ＰＺＴよりなるキャパシタ誘電体膜３７が形成されており、前記キャパシタ誘電体膜３７上には、ＰｔやＩｒ、あるいはＩｒＯｘよりなる上部キャパシタ電極３８が形成されている。前記下部キャパシタ電極３６、強誘電体キャパシタ誘電体膜３７および上部キャパシタ電極３８は、ＦｅＲＡＭの強誘電体キャパシタを構成する。
【００６１】
次に、図６のＦｅＲＡＭの製造工程を、図７（Ａ）〜１０（Ｈ）を参照しながら説明する。
【００６２】
図７（Ａ）を参照するに、前記Ｓｉ基板３１中に、例えばシャロートレンチ法により、素子分離構造３０Ａを形成し、素子領域を画成する。
【００６３】
次いで、前記素子分離構造３０Ａにより画成された素子領域上に、通常のＭＯＳトランジスタの形成方法と同様にして、前記ゲート絶縁膜３２を介して形成されたゲート電極３３と、前記ゲート電極３３の両側において前記Ｓｉ基板３１中に形成された拡散領域３１Ａ，３１Ｂを形成し、ＦｅＲＡＭのメモリセルトランジスタを形成する。
【００６４】
次に図７（Ｂ）の工程において、前記メモリセルトランジスタが形成されたＳｉ基板３１上に、例えばＣＶＤ法によりシリコン酸化膜を堆積し、前記層間絶縁膜３４を形成する。さらにこのようにして形成された層間絶縁膜３４の表面をＣＭＰ（化学的機械的研磨）法などにより研磨し、前記層間絶縁膜３４の表面を平坦化する。
【００６５】
さらに図７（Ｂ）の工程では、リソグラフィー技術及びエッチング技術により前記層間絶縁膜３４に前記拡散領域３１Ａに達するコンタクトホール３４ａを形成し、図７（Ｃ）の工程において前記層間絶縁膜３４上にスパッタ法などにより、タングステン（Ｗ）膜を前記コンタクトホール３４ａを充填するように堆積した後、前記層間絶縁膜３４の表面が露出するまでＣＭＰ法により研磨する。その結果、前記コンタクトホール３４ａ内に埋め込まれた導電性プラグ３４Ａが、前記拡散領域３１Ａに電気的に接続された状態で形成される。
【００６６】
図７（Ｃ）の工程では、さらにスパッタ法などにより前記層間絶縁膜３４上にＷ膜を堆積し、これをリソグラフィー技術及びエッチング技術によりパターニングすることにより、Ｗ膜よりなり、前記導電性プラグ３４Ａを介して前記拡散領域３１Ａに接続されたビット線ＢＬが形成される。
【００６７】
次に図８（Ｄ）の工程において、前記ビットＢＬ線が形成された層間絶縁膜３４上に、例えばＣＶＤ法によりシリコン酸化膜を堆積し、別の層間絶縁膜３５を形成する。さらにリソグラフィー技術及びエッチング技術により、前記層間絶縁膜３５に、その下の層間絶縁膜３４を貫通して前記拡散領域３１Ｂに達するコンタクトホール３５ｂを形成する。
【００６８】
さらに図８（Ｅ）の工程において、例えばスパッタ法などにより前記層間絶縁膜３５上にＷ膜を堆積した後、前記層間絶縁膜３５の表面が露出するまでＣＭＰ法により研磨し、コンタクトホール３５ｂを充填し拡散領域３１Ｂに電気的に接続された導電性プラグ３５Ｂが形成される。
【００６９】
図８（Ｅ）の工程では、さらにスパッタ法により、前記層間絶縁膜３５上に下部キャパシタ電極３６を構成するバリアメタルおよび下部電極層３６０を堆積する。
【００７０】
次に、図９（Ｆ）の工程において図１のＭＯＣＶＤ装置１０を使い、前記下部電極層３６０上にＰｂ（ＴＨＤ）_２，Ｚｒ（ＤＭＨＤ）_４，Ｔｉ（ｉＰｒＯ）_２（ＴＨＤ）_２などの有機金属原料を、単位体積あたりの熱容量が５６．５Ｊ／ｍｌ未満、より好ましくは５０Ｊ／ｍｌ以下の有機溶媒中に溶解し、形成された液体原料を気化器１２に送り、先の実施例と同様な条件下でＰＺＴ膜３７０を形成する。前記有機溶媒としては、先に表２に示したような材料を使うことができる。
【００７１】
さらに図９（Ｇ）の工程において、前記ＰＺＴ膜３７０上に、スパッタ法により、ＰｔあるいはＩｒ，あるいはＩｒＯｚ膜を堆積し、上部電極層３８０を形成する。
【００７２】
最後に図１０（Ｈ）の工程において、リソグラフィーおよびエッチング技術により前記膜３６０〜３８０をパターニングし、下部キャパシタ電極３６、強誘電体キャパシタ絶縁膜３７および上部キャパシタ電極３７を形成し、先に図６で説明した構造が得られる。
【００７３】
以上、本発明を好ましい実施例について説明したが、本発明は上記の特定の実施例に限定されるものではなく、特許請求の範囲に記載した要旨内において様々な変形・変更が可能である。
【００７４】
（付記１） 有機溶媒中に溶解された有機金属原料を気化させ、有機金属原料ガスを形成する工程と、
前記有機金属原料ガスを、被処理基板を保持した処理容器中に導入する工程と、
前記処理容器中における前記有機金属原料ガスの分解により、前記被処理基板上に薄膜を形成する工程とよりなる薄膜形成方法において、
前記有機溶媒は、２−メチルペンタン，３−メチルペンタン，２，２−ジメチルブタン，２，３−ジメチルブタン，シクロペンタン，メチラール，エチルホルメート，メチルアセテートおよびｎ−プロピルアミンよりなる群から選ばれることを特徴とする薄膜形成方法。
【００７５】
（付記２） 前記有機溶媒は、２，２−ジメチルブタン，２，３−ジメチルブタン，シクロペンタン，メチラールおよびｎ−プロピルアミンよりなる群から選ばれることを特徴とする請求項１記載の薄膜形成方法。
【００７６】
（付記３） 前記有機溶媒は、２，２−ジメチルブタン，シクロペンタンおよびメチラールよりなる群から選ばれることを特徴とする請求項１記載の薄膜形成方法。
【００７７】
（付記４） 前記有機溶媒は、シクロペンタンまたはメチラールよりなることを特徴とする請求項１記載の薄膜形成方法。
【００７８】
（付記５） 前記有機金属原料は、１８０〜３００℃の範囲の気化温度を有することを特徴とする請求項１記載の薄膜形成方法。
【００７９】
（付記６） 前記有機金属原料は、Ｐｂの有機金属原料としてＰｂ（ＴＨＤ）_２を、Ｚｒの有機金属原料としてＺｒ（ＤＭＨＤ）_４を，Ｔｉの有機金属原料としてＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を含むことを特徴とする請求項５記載の薄膜形成方法。
【００８０】
（付記７） 前記有機金属原料は、Ｂａの有機金属原料としてＢａ（ＴＨＤ）_２を、Ｓｒの有機金属原料としてＳｒ（ＴＨＤ）_２を、またＴｉの有機金属原料としてＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２含むことを特徴とする請求項５記載の薄膜形成方法。
【００８１】
（付記８） 前記有機金属原料は、Ｂｉの有機金属原料としてＢｉ（ＴＨＤ）_２およびＢｉ（ｐｈ）_３のいずれか一方を、Ｓｒの有機金属原料としてＳｒ（ＴＨＤ）_２を、Ｔａの有機金属原料としてＴａ（ＯＥｔ）_５とＴａ（Ｏ−ｉＰｒ）_４（ＴＨＤ）のいずれか一方を含むことを特徴とする請求項５記載の薄膜形成方法。
【００８２】
（付記９） 前記有機金属原料は、Ｂｉの有機金属原料としてＢｉ（ＴＨＤ）_３とＢｉ（ｐｈ）_３のいずれか一方を、Ｌａの有機金属原料としてＬａ（ＴＨＤ）_３を、Ｔｉの有機金属原料としてＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２のいずれか一方を含むことを特徴とする請求項５記載の薄膜形成方法。
【００８３】
（付記１０） 前記有機金属原料は、Ｂｉの有機金属原料としてＢｉ（ＴＨＤ）_２とＢｉ（ｐｈ）_３のいずれか一方を、Ｔｉの有機金属原料としてＴｉ（Ｏ−ｉＰｒ）_２（ＴＨＤ）_２を含むことを特徴とする請求項５記載の薄膜形成方法。
【００８４】
（付記１１） 強誘電体キャパシタを含む半導体装置の製造方法であって、
下部電極上に強誘電体膜を形成する工程と、
前記強誘電体膜上に上部電極を形成する工程とを含み、
前記強誘電体膜を形成する工程は、
有機溶媒中に溶解された有機金属原料を気化させ、有機金属原料ガスを形成する工程と、
前記有機金属原料ガスの分解により、前記下部電極上に前記強誘電体膜を形成する工程とよりなり、
前記有機溶媒は、２−メチルペンタン，３−メチルペンタン，２，２−ジメチルブタン，２，３−ジメチルブタン，シクロペンタン，メチラール，エチルホルメート，メチルアセテートおよびｎ−プロピルアミンよりなる群から選ばれることを特徴とする半導体装置の製造方法。
【００８５】
【発明の効果】
本発明によれば、気化器において有機金属原料を気化する工程を含む成膜方法において、有機金属原料を前記気化器に、２−メチルペンタン，３−メチルペンタン，２，２−ジメチルブタン，２，３−ジメチルブタン，シクロペンタン，メチラール，エチルホルメート，メチルアセテートおよびｎ−プロピルアミンよりなる群から選ばれる単位体積あたりの熱容量が５６．６Ｊ／ｍｌ未満の有機溶媒に溶解して供給することにより、前記気化器中における有機金属原料の昇温および気化が短時間になされ、部分的に分解した有機金属原料が反応容器に供給されることによるパーティクルの発生が効果的に抑制される。
【図面の簡単な説明】
【図１】本発明で使われるＭＯＣＶＤ装置の構成を示す図である。
【図２】図１のＭＯＣＶＤ装置の気化器中における液体原料の昇温特性を示す図である。
【図３】図１のＭＯＣＶＤ装置の気化器中における液体原料の昇温特性を示す別の図である。
【図４】図１のＭＯＣＶＤ装置で使われる有機金属原料の一例を示す図である。
【図５】本発明の第１実施例によるＰＺＴ膜の成膜工程において基板上に堆積したパーティクルの数と、使われた有機溶媒の熱容量との関係を示す図である。
【図６】本発明第２実施例によるＦｅＲＡＭの構成を示す図である。
【図７】（Ａ）−（Ｃ）は、図６のＦｅＲＡＭの製造工程を示す図（その１）である。
【図８】（Ｄ）−（Ｅ）は、図６のＦｅＲＡＭの製造工程を示す図（その２）である。
【図９】（Ｆ）−（Ｇ）は、図６のＦｅＲＡＭの製造工程を示す図（その３）である。
【図１０】（Ｈ）は、図６のＦｅＲＡＭの製造工程を示す図（その４）である。
【符号の説明】
１０ ＭＯＣＶＤ装置
１１ 成膜室
１１Ａ サセプタ
１１Ｂ 排気ライン
１２ 気化器
１２_１，１２_２，１２_３ 原料容器
１２Ａ 原料ガス供給ライン
１２Ｂ バイパスライン
１２ａ，１２ｂ バルブ
１３ ガス混合器
１３Ａ 酸化ガスライン
１４ 真空ポンプ
１５ コールドトラップ
１６，２６ 除害装置
１７ 加熱ジャケット
３０ ＦｅＲＡＭ
３０Ａ 素子分離構造
３１ Ｓｉ基板
３１Ａ，３１Ｂ 拡散領域
３２ ゲート絶縁膜
３３ ゲート電極
３４，３５ 層間絶縁膜
３６ 下部キャパシタ電極
３７ 強誘電体キャパシタ絶縁膜
３８ 上部キャパシタ電極
３６０ 下部電極層
３７０ 強誘電体膜
３８０ 上部電極層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a thin film using a MOCVD method.
[0002]
Semiconductor storage devices such as so-called DRAMs or SRAMs are widely used as high-speed main storage devices in information processing devices such as computers, but these are volatile storage devices, and information stored when power is turned off. Will be lost. On the other hand, a nonvolatile magnetic disk device has conventionally been used as a large-capacity auxiliary storage device for storing programs and data.
[0003]
However, the magnetic disk device has disadvantages that it is large, mechanically fragile, consumes large power, and has a low access speed when reading and writing information. On the other hand, recently, as a nonvolatile auxiliary storage device, an EEPROM or a flash memory that stores information in the form of electric charges in a floating gate electrode has been often used. In particular, since a flash memory has a cell configuration similar to that of a DRAM, it can be easily formed at a large integration density, and is expected as a large-capacity storage device comparable to a magnetic disk device.
[0004]
On the other hand, in an EEPROM or a flash memory, information is written by injecting hot electrons into a floating gate electrode through a tunnel insulating film, so that it takes a long time to write, and information writing and erasing are repeated. This causes a problem that the tunnel insulating film is deteriorated. If the tunnel insulating film is deteriorated, the writing or erasing operation becomes unstable.
[0005]
On the other hand, a ferroelectric memory device (hereinafter referred to as FeRAM) that stores information in the form of spontaneous polarization of a ferroelectric film has been proposed. In such an FeRAM, each memory cell transistor is formed of a single MOSFET as in the case of a DRAM, and the dielectric film in the memory cell capacitor is formed of PZT (Pb (Zr, Ti) O). ₃ ) Or PLZT ((Pb, La) (Zr, Ti) O ₃ ), And SBT (SrBi ₂ Ta ₂ O ₃ ), Etc., and can be integrated at a high integration density. In addition, the FeRAM controls the spontaneous polarization of the ferroelectric capacitor by applying an electric field. Therefore, the writing speed is 1000 times or more faster than an EEPROM or a flash memory in which writing is performed by injecting hot electrons, and power consumption is increased. It has the advantageous feature of being reduced to about 1/10. Furthermore, since it is not necessary to use a tunnel oxide film, the lifetime is long, and it is considered that the number of times of rewriting 100,000 times of the flash memory can be secured.
[0006]
[Prior art]
Conventionally, ferroelectric films used in such FeRAMs are formed by a sol-gel method or a sputtering method. However, as the miniaturization of semiconductor devices progresses, particularly, beyond the 0.18 μm generation, these conventional methods require a finer structure. It is predicted that coverage of a large step will be difficult. Under such circumstances, the CVD method is considered to be an indispensable technique as a technique for forming a ferroelectric film used in the next generation FeRAM. In particular, when forming a ferroelectric film, it is necessary to supply a raw material containing a metal element such as Pb, Zr, or Ti. Therefore, if the CVD method is the MOCVD method using an organic metal raw material of these metal elements, I have no choice.
[0007]
FIG. 1 shows a schematic configuration of an MOCVD apparatus 10 conventionally used for forming a ferroelectric film by the MOCVD method.
[0008]
Referring to FIG. 1, in a MOCVD apparatus 10, a raw material container 12 is provided. ₁ , 12 ₂ , 12 ₃ From Pb (THD) ₂ (Bis (2,2,6,6-tetramethyl-3,5-heptanedionate), Zr (DMHD) ₄ (Tetrakis 2,6-dimethyl-3,5-heptadionate zirconium), Ti (O-iPr) ₂ (THD) ₂ It is obtained by dissolving a solid organic metal raw material such as (di (isopropoxy) bis (2,2,6,6-tetramethyl-3,5-heptanedionato) titanium) in an organic solvent such as THF (tetrahydrofuran). The liquid raw material is supplied to the vaporizer 12, and the organometallic vapor phase raw material formed by vaporization in the vaporizer 12 is supplied to the gas mixer 13 via the raw gas supply line 12A. The organometallic gas-phase raw material supplied to the gas mixer 13 is mixed with oxygen gas supplied via a gas line 13A, and the mixed gas thus formed is supplied from a shower head (not shown) The substrate W is supplied to the film forming chamber 11 holding the substrate W to be processed on the susceptor 11A. The metal organic vapor source introduced into the film forming chamber 11 is thermally decomposed on the surface of the substrate W to be processed, and as a result, a ferroelectric film such as PZT is formed on the surface of the substrate W to be processed. .
[0009]
The film forming chamber 11 is connected to a vacuum pump 14 via an exhaust line 11B, and as a result, a reaction product generated as a result of thermal decomposition of the organometallic vapor phase material in the film forming chamber 11, The unreacted organometallic raw material that has not been removed is exhausted from the exhaust line 11B together with the organic solvent component. The vaporizer 12 is connected to the vacuum pump 14 by a valve 12b and a bypass line 12B. When a film is not formed in the film forming chamber 11, the organic metal vapor formed in the vaporizer 12 is formed. The phase material is exhausted through the valve 12b and the bypass line 12B.
[0010]
The bypass line 12B merges with the exhaust line 11B on the upstream side of the vacuum pump 14. A cold trap 15 is provided between the exhaust line 11B and the vacuum pump 14 at the merging position, and the gas is exhausted through the exhaust line 11B or 12B. The unreacted organometallic raw material is captured. Further, an abatement device 16 for removing the organic solvent is provided downstream of the vacuum pump 14.
[0011]
In the MOCVD apparatus 10 of FIG. 1, the pipes 12A and 12B and the valves 12a and 12b between the vaporizer 12 and the cold and the wrap 15 are heated by the heating jacket 17 to avoid the deposition of the organometallic raw material.
[0012]
[Patent Document 1]
JP-A-11-199233
[0013]
[Patent Document 2]
JP-A-9-199445
[0014]
[Problems to be solved by the invention]
In the formation of a ferroelectric film using the MOCVD method, it is important to achieve uniformity in the thickness and composition of the obtained ferroelectric film, and various studies have been made. At the same time, it is important to suppress the generation of particles during film formation. It has been found that such particles tend to be generated during the oxide formation process.
[0015]
In general, the CVD method is used not only for forming a thin film on a substrate but also for forming fine particles. Suppression of the generation of fine particles in a thin film forming process using the CVD method is important, including clarification of its mechanism. It has become a challenge.
[0016]
Accordingly, it is a general object of the present invention to provide a novel and useful method of forming a thin film by MOCVD, which solves the above-mentioned problems.
[0017]
A more specific object of the present invention is to suppress generation of fine particles in a thin film forming method by MOCVD.
[0018]
[Means for Solving the Problems]
The present invention solves the above problems by a step of vaporizing an organometallic raw material dissolved in an organic solvent to form an organometallic raw material gas, and introducing the organometallic raw material gas into a processing vessel holding a substrate to be processed. And a step of forming a thin film on the substrate to be processed by decomposing the organometallic source gas in the processing container, wherein the organic solvent is 2-methylpentane, 3-methyl The problem is solved by a thin film forming method characterized by being selected from the group consisting of pentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, ethyl formate, methyl acetate and n-propylamine. .
[0019]
According to the present invention, an organic solvent having a heat capacity per unit volume of less than 56.5 J / ml, more preferably about 50 J / ml or less is used as an organic solvent for dissolving an organometallic raw material. The temperature rises rapidly when the organic metal raw material dissolved in the gas is vaporized, and it is possible to suppress the decomposition or deterioration of the organic metal raw material at the time of raising the temperature. As a result, it is possible to solve the problem that the organic metal raw material in which the organic metal raw material is partially decomposed into the reaction vessel of the MOCVD apparatus is introduced to generate particles. For example, by using an organic solvent having a heat capacity per unit volume of less than 56.5 J / ml, the number of particles deposited on a 6-inch diameter substrate can be suppressed to about 200 or less. By using an organic solvent having a heat capacity per unit volume of 50 J / ml or less, the number of particles deposited on the same 6-inch diameter substrate can be suppressed to about 150 or less. Further, by using an organic solvent having a heat capacity per unit deposition of 40 J / ml or less, the number of particles deposited on the same 6-inch diameter substrate can be suppressed to about 100 or less. In addition, by using an organic solvent having a heat capacity per unit deposition of about 30 J / ml, the number of particles volumed on the same 6-inch diameter substrate can be suppressed to about 50 or less.
[0020]
As the organic solvent having a heat capacity per unit volume of 50 J / ml or less, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, n-propylamine and the like can be used. As the organic solvent having a heat capacity per unit volume of 40 J / ml or less, 2,2-dimethylbutane, cyclopentane, methylal, and the like can be used. Further, as the organic solvent having a heat capacity per unit volume of about 30 J / ml, cyclopentane, methylal and the like can be used.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
[First embodiment]
The inventor of the present invention conducted an experiment for forming a PZT film using the MOCVD apparatus shown in FIG. 1 in the research on which the present invention is based, and found that the heat capacity of the organic solvent used to dissolve the organometallic material was increased. It has been found that the number of particles contained in the formed PZT film changes depending on the value of.
[0022]
More specifically, the inventor of the present invention carried out Pb (THD) ₂ , Zr (DMHD) ₄ And Ti (O-iPr) ₂ (THD) ₂ Are dissolved in a THF (tetrahydrofuran) solvent having a heat capacity per unit volume of 56.5 J / ml to form liquid raw materials of Pb, Zr, and Ti. ₁ ~ 12 ₃ An experiment was performed in which a PZT film was formed in a processing vessel 11 that supplies a substrate to be processed having a diameter of 6 inches by supplying the PZT film to a vaporizer 12.
[0023]
In this experiment, the liquid raw material was fed to the vaporizer 12 at a flow rate of 1.2 ml / min in total, and was vaporized at a temperature of 190 ° C. in the vaporizer 12 to form an organometallic raw material gas. The organometallic raw material gas formed as described above is introduced together with a carrier gas of 300 SCCM into the processing vessel 11 holding the substrate W having a diameter of 6 inches, and oxygen gas is further introduced into the processing vessel 11 at 2500 SCCM. By supplying at a flow rate, a PZT film was formed on the substrate to be processed W at a substrate temperature of 580 ° C. to a thickness of 120 nm.
[0024]
In this experiment, the substrate temperature was set to 230 ° C. at which the deposition of the PZT film did not occur. Was examined. As a result, when the PZT film was deposited under the above conditions, it was observed that 209 particles were deposited on the surface of the substrate W having a diameter of 6 inches.
[0025]
In addition, the inventor of the present invention found that in the experiment which forms the basis of the present invention, the organometallic raw material Pb (THD) ₂ , Zr (DMHD) ₄ And Ti (O-iPr) ₂ (THD) ₂ Are dissolved in a butyl acetate solvent having a heat capacity per unit volume of 175.2 J / ml to form liquid raw materials of Pb, Zr, and Ti. ₁ ~ 12 ₃ An experiment was performed in which a PZT film was formed in a processing vessel 11 that supplies a substrate to be processed having a diameter of 6 inches by supplying the PZT film to a vaporizer 12.
[0026]
Also in this experiment, the liquid raw material was supplied to the vaporizer 12 at a flow rate of 1.2 ml / min in total, and was vaporized at a temperature of 190 ° C. in the vaporizer 12 to form an organometallic raw material gas. The organic metal raw material gas formed as described above is introduced into a processing vessel 11 holding a 6-inch-diameter substrate W to be processed, together with a carrier gas of 300 SCCM and an oxygen gas of 2500 SCCM. A PZT film was formed at a substrate temperature of 580 ° C. to a thickness of 114 nm.
[0027]
Also in this experiment, the substrate temperature was set to 230 ° C. at which the deposition of the PZT film did not occur, and the number of particles deposited on the surface of the substrate W was examined. As a result, when the PZT film was deposited under the above conditions, it was observed that 1163 particles had been deposited on the surface of the substrate W having a diameter of 6 inches.
Table 1 below summarizes the results of the above experiments.
[0028]
[Table 1]

Referring to Table 1, when THF was used as a solvent, the obtained PZT film had a thickness of 120 nm, a Pb composition in the film of 1.16 and a Zr composition of 0.42, It can be seen that when butyl acetate was used as the solvent, a PZT film having a substantially similar Pb composition of 1.17 and a substantially similar Pb composition of 1.17 and a Zr composition of 0.45 was obtained. On the other hand, when butyl acetate is used as the solvent, as described above, the number of particles on the substrate is greatly increased as compared with the case where THF is used as the solvent.
[0029]
As described above, the reason why the number of particles contained in the film varies depending on the solvent used is probably that the difference in heat capacity of the solvent in the vaporizer 12 causes a difference in the rate of temperature rise, and a solvent having a particularly large heat capacity was used. In this case, it is considered that it takes time until the temperature of the liquid raw material reaches a predetermined vaporization temperature.
[0030]
FIG. 2 shows a heating curve of the solvent generated in the vaporizer 12 when the THF solvent and the butyl acetate solvent are supplied to the vaporizer 12 at a rate of 1.2 ml / min.
[0031]
Referring to FIG. 2, when butyl acetate having a large heat capacity is used as a solvent, the heating time until reaching a predetermined vaporization temperature of 190 ° C. is about 3 times longer than when THF having a small heat capacity is used as a solvent. It can be seen that it has increased by a factor of two.
[0032]
FIG. 3 shows the time required for the solvent temperature to reach a predetermined vaporization temperature when the organic solvent having various heat capacities is supplied to the vaporizer 12 at various flow rates.
[0033]
Referring to FIG. 3, when the flow rate of the organic solvent is constant, the time until the temperature of the solvent reaches the predetermined vaporization temperature is shorter as the heat capacity of the solvent is smaller, and is smaller as the flow rate of the solvent is smaller. It turns out that it is short.
[0034]
In the MOCVD apparatus of FIG. 1, most of the liquid raw material supplied to the vaporizer 12, for example, 90 to 99% is a solvent, and the effect of the heat capacity of the organic metal raw material can be almost ignored. Therefore, when the heat capacity of the solvent is large, it takes time to evaporate the liquid raw material, during which time the organic metal raw material dissolved in the liquid raw material partially decomposes or deteriorates, and the organic metal raw material thus degraded It is considered that particles are generated by introducing the particles into the processing container 11. The organometallic raw material has a structure in which a metal atom is surrounded by a plurality of ligands as shown in FIG. 4, and one or more of these ligands are desorbed, so that the vaporization temperature increases. Change.
[0035]
FIG. 5 shows the relationship between the heat capacity of the solvent in the liquid raw material and the number of particles in the obtained PZT film, obtained from the above experiment.
[0036]
Referring to FIG. 5, by reducing the heat capacity per unit volume of the solvent to less than 56.5 J / ml, the number of particles generated on a 6-inch diameter substrate can be reduced to almost 200 or less. I understand.
[0037]
Further, FIG. 5 shows that when the heat capacity per unit volume of the solvent is about 50 J / ml or less, the number of particles on a 6-inch diameter substrate can be suppressed to about 150 or less. Also, it can be seen that when the heat capacity per unit volume of the solvent is about 40 J / ml or less, the number of particles on the substrate can be suppressed to about 100 or less. Further, when the heat capacity per unit volume of the organic solvent is about 30 J / ml, it can be seen that the number of particles on the substrate can be suppressed to about 50 or less.
[0038]
As the solvent capable of reducing the number of particles on the substrate as compared with the case of the above experiment, those shown in Table 2 below can be used.
[0039]
[Table 2]

For example, 2-methylpentane having a heat capacity of 51.5 J / ml is used as the organic solvent, and Pb (THD) is contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material container 12. ₁ ~ 12 ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and a PZT film obtained when a PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 169 or less.
[0040]
Further, 3-methylpentane having a heat capacity of 55.9 J / ml was used as the organic solvent, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material container 12. ₁ ~ 12 ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and a PZT film obtained when a PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 240 or less.
[0041]
Further, 2,2-dimethylbutane having a heat capacity of 35.8 J / ml was used as the organic solvent, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material containers 121 to 12. ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and a PZT film obtained when a PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 43 or less.
[0042]
Further, 2,3-dimethylbutane having a heat capacity of 47.5 J / ml was used as the organic solvent, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material container 12. ₁ ~ 12 ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and a PZT film obtained when a PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 140 or less.
[0043]
Further, cyclopentane having a heat capacity of 32.5 J / ml was used as the organic solvent, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material container 12. ₁ ~ 12 ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and a PZT film obtained when a PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 17 or less.
[0044]
Further, methylal having a heat capacity of 31.1 J / ml was used as the organic solvent, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material container 12. ₁ ~ 12 ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and a PZT film obtained when a PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 5 or less.
[0045]
Further, as the organic solvent, ethyl formate having a heat capacity of 51.6 J / ml was used, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material containers 121 to 12. ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and a PZT film obtained when a PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 170 or less.
[0046]
Further, methyl acetate having a heat capacity of 56.4 J / ml was used as the organic solvent, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material container 12. ₁ ~ 12 ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and the PZT film obtained when the PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 208 or less.
[0047]
Further, n-propylamine having a heat capacity of 45.9 J / ml was used as the organic solvent, and Pb (THD) was contained therein. ₂ , Zr (DMHD) ₂ And Ti (O-iPr) ₂ (THD) ₂ Is dissolved to produce a liquid raw material of Pb, Zr and Ti, the liquid raw material thus prepared is placed in the raw material container 12. ₁ ~ 12 ₃ To the vaporizer 12 so that the total flow rate is 1.2 ml / min, and vaporized at a temperature of 190 ° C., thereby supplying the processing vessel 11 with a nitrogen carrier gas at a flow rate of 300 SCCM. Oxygen gas is supplied into the processing vessel 11 at a flow rate of 2500 SCCM, and the PZT film obtained when the PZT film is formed on a 6-inch diameter substrate at a substrate temperature of 580 ° has a diameter of 0.2 μm or more. The number of particles can be suppressed to about 124 or less.
[0048]
As described above, the rate of temperature rise of such a liquid material is mainly determined by the heat capacity of the organic solvent, and is substantially independent of the type of the organometallic material dissolved in the organic solvent. . In the example in which the PZT film is formed, Pb (THD) is used as an organic metal raw material of Pb. ₂ And Zr (DMHD) as an organic metal raw material for Zr ₄ And Ti (O-iPr) as an organometallic raw material for Ti ₂ (THD) ₂ However, the vaporization temperatures of these compounds are in the range of 180 to 200 ° C., 250 to 270 ° C., and 200 to 220 ° C., respectively. The present invention is not limited to the PZT film forming process described above, and is considered to be effective even when an organic metal material having a similar vaporization temperature range, for example, a vaporization temperature in the range of 180 to 300 ° C. is used.
[0049]
In addition, the above-mentioned organic solvent can be used in other films, for example, BST (BaSrTiO. ₃ ) Film or SBT (SrBi ₂ (Ta, Nb) ₂ O ₉ ) Membrane, BLT (BiLa) ₄ Ti ₃ O ₁₂ Membrane, BIT (Bi ₄ Ti ₃ O ₁₂ It is considered to be effective also in the formation of a film.
[0050]
For example, when a BST film is formed, Ba (THD) is used as an organic metal raw material of Ba in an organic solvent having a heat capacity per unit volume of less than 56.5 J / ml. ₂ And Sr (THD) as an organometallic raw material of Sr in the organic solvent. ₂ And a liquid raw material obtained by dissolving Ti (O-iPr) in the organic solvent as an organic metal raw material for Ti. ₂ (THD) ₂ It is possible to use a liquid raw material obtained by dissolving
[0051]
When an SBT film is formed, Bi (ph) is used as an organometallic raw material of Bi in the organic solvent. ₃ And Sr (THD) as an organometallic raw material of Sr in the organic solvent. ₂ And Ta (O-iPr) in the organic solvent as an organic metal raw material of Ta. ₄ (THD) and Nb (O-iPr) as an organic metal raw material of Nb in the organic solvent. ₅ It is possible to use a liquid raw material obtained by dissolving
[0052]
Further, when a BLT film is formed, Bi (ph) is used as an organometallic raw material of Bi in the organic solvent. ₃ And a liquid raw material obtained by dissolving La (THD) as an organic metal raw material of La in the organic solvent. ₃ And a liquid raw material obtained by dissolving Ti (O-iPr) in the organic solvent as an organic metal raw material for Ti. ₂ It is possible to use a liquid raw material obtained by dissolving (THD).
[0053]
When a BIT film is formed, Bi (ph) is used as an organometallic raw material of Bi in the organic solvent. ₃ And a liquid raw material obtained by dissolving Ti (O-iPr) in the organic solvent as an organic metal raw material for Ti. ₂ It is possible to use a liquid raw material obtained by dissolving (THD).
[0054]
In addition, as a raw material of Bi, Bi (ph) ₃ Besides Bi (THD) ₃ It is possible to use As a raw material of Ta, Ta (O-iPr) ₄ (THD) and Ta (OEt) ₅ It is possible to use
[Second embodiment]
Next, a manufacturing process of the FeRAM according to the second embodiment of the present invention using the MOCVD apparatus 10 of FIG. 1 will be described.
[0055]
FIG. 6 shows the configuration of the FeRAM 30 according to the second embodiment of the present invention.
[0056]
Referring to FIG. 6, the FeRAM 30 is formed on a Si substrate 31 having an element region defined by an element isolation structure 30A. On the Si substrate 31, a gate insulating film corresponding to the active region is provided. A gate electrode 33 formed through the gate electrode 32 and source and drain diffusion regions 31A and 31B formed in the Si substrate 31 on both sides of the gate electrode 33 are formed.
[0057]
Further, an interlayer insulating film 34 is formed on the Si substrate 31, and a conductive plug 34A electrically connected to one of the diffusion regions 31A is embedded in the interlayer insulating film 34. Further, on the interlayer insulating film 34, a bit line BL electrically connected to the diffusion region 31A via the plug 34A is formed.
[0058]
An interlayer insulating film 35 is further formed on the interlayer insulating film 34 on which the bit line BL is formed, and the interlayer insulating film 35 penetrates the interlayer insulating film 34 and electrically connects to the other diffusion region 31B. Is embedded in the conductive plug 35B.
[0059]
A lower capacitor electrode 36 having a structure in which a barrier metal layer and a lower electrode layer are sequentially laminated is formed on the interlayer insulating film 35 in which the conductive plug 35B is embedded. In the lower capacitor electrode 36, the lower electrode layer is composed of an Ir layer or a Pt layer. When a Pt layer is used as the lower electrode layer, an Ir layer is formed as a barrier metal layer, and an IrOx layer, for example, is formed as an adhesion layer on the Ir layer. The Pt lower electrode layer is formed on the IrOx layer thus formed. On the other hand, when the lower electrode layer is an Ir layer, the lower capacitor electrode 36 is composed of a single Ir layer. FIG. 6 shows a case where an Ir layer is used as the lower capacitor electrode 36.
[0060]
A capacitor dielectric film 37 made of PZT is formed on the lower capacitor electrode 36, and an upper capacitor electrode 38 made of Pt, Ir, or IrOx is formed on the capacitor dielectric film 37. . The lower capacitor electrode 36, ferroelectric capacitor dielectric film 37 and upper capacitor electrode 38 constitute a ferroelectric capacitor of FeRAM.
[0061]
Next, a manufacturing process of the FeRAM of FIG. 6 will be described with reference to FIGS.
[0062]
Referring to FIG. 7A, an element isolation structure 30A is formed in the Si substrate 31 by, for example, a shallow trench method to define an element region.
[0063]
Then, a gate electrode 33 formed on the element region defined by the element isolation structure 30A via the gate insulating film 32 in the same manner as a normal MOS transistor forming method, On both sides, diffusion regions 31A and 31B formed in the Si substrate 31 are formed, and memory cell transistors of FeRAM are formed.
[0064]
Next, in the step of FIG. 7B, a silicon oxide film is deposited on the Si substrate 31 on which the memory cell transistors are formed by, for example, a CVD method, and the interlayer insulating film 34 is formed. Further, the surface of the interlayer insulating film 34 thus formed is polished by a CMP (chemical mechanical polishing) method or the like, and the surface of the interlayer insulating film 34 is flattened.
[0065]
Further, in the step of FIG. 7B, a contact hole 34a reaching the diffusion region 31A is formed in the interlayer insulating film 34 by lithography and etching techniques. After a tungsten (W) film is deposited so as to fill the contact hole 34a by a sputtering method or the like, it is polished by a CMP method until the surface of the interlayer insulating film 34 is exposed. As a result, the conductive plug 34A embedded in the contact hole 34a is formed in a state of being electrically connected to the diffusion region 31A.
[0066]
In the step of FIG. 7C, a W film is further deposited on the interlayer insulating film 34 by a sputtering method or the like, and is patterned by a lithography technique and an etching technique. , A bit line BL connected to the diffusion region 31A is formed.
[0067]
Next, in the step of FIG. 8D, a silicon oxide film is deposited on the interlayer insulating film 34 on which the bit BL lines have been formed by, for example, a CVD method, and another interlayer insulating film 35 is formed. Further, a contact hole 35b is formed in the interlayer insulating film 35 through the interlayer insulating film 34 thereunder and reaches the diffusion region 31B by lithography and etching.
[0068]
8E, a W film is deposited on the interlayer insulating film 35 by, for example, a sputtering method, and then polished by a CMP method until the surface of the interlayer insulating film 35 is exposed. A conductive plug 35B that is filled and electrically connected to the diffusion region 31B is formed.
[0069]
In the step of FIG. 8E, a barrier metal constituting the lower capacitor electrode 36 and a lower electrode layer 360 are further deposited on the interlayer insulating film 35 by a sputtering method.
[0070]
Next, in the step of FIG. 9F, Pb (THD) is formed on the lower electrode layer 360 by using the MOCVD apparatus 10 of FIG. ₂ , Zr (DMHD) ₄ , Ti (iPrO) ₂ (THD) ₂ Is dissolved in an organic solvent having a heat capacity per unit volume of less than 56.5 J / ml, more preferably 50 J / ml or less, and the formed liquid material is sent to the vaporizer 12 to carry out the previous operation. The PZT film 370 is formed under the same conditions as in the example. As the organic solvent, the materials shown in Table 2 can be used.
[0071]
9G, a Pt, Ir, or IrOz film is deposited on the PZT film 370 by sputtering to form an upper electrode layer 380.
[0072]
Finally, in the step of FIG. 10H, the films 360 to 380 are patterned by lithography and etching techniques to form a lower capacitor electrode 36, a ferroelectric capacitor insulating film 37, and an upper capacitor electrode 37. Is obtained.
[0073]
As described above, the present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the above-described specific embodiments, and various modifications and changes can be made within the scope of the claims.
[0074]
(Supplementary Note 1) a step of vaporizing an organometallic raw material dissolved in an organic solvent to form an organometallic raw material gas;
A step of introducing the organometallic raw material gas into a processing vessel holding a substrate to be processed,
Forming a thin film on the substrate to be processed by decomposing the organometallic source gas in the processing container,
The organic solvent is selected from the group consisting of 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, ethyl formate, methyl acetate and n-propylamine. A thin film forming method.
[0075]
(Supplementary Note 2) The thin film formation according to claim 1, wherein the organic solvent is selected from the group consisting of 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, and n-propylamine. Method.
[0076]
(Supplementary note 3) The method according to claim 1, wherein the organic solvent is selected from the group consisting of 2,2-dimethylbutane, cyclopentane, and methylal.
[0077]
(Supplementary Note 4) The method according to claim 1, wherein the organic solvent is made of cyclopentane or methylal.
[0078]
(Supplementary Note 5) The method of forming a thin film according to Claim 1, wherein the organometallic raw material has a vaporization temperature in a range of 180 to 300 ° C.
[0079]
(Supplementary Note 6) The organometallic raw material is Pb (THD) as an organometallic raw material of Pb. ₂ With Zr (DMHD) as the organometallic raw material for Zr ₄ And Ti (O-iPr) as an organometallic raw material for Ti ₂ (THD) ₂ 6. The thin film forming method according to claim 5, comprising:
[0080]
(Supplementary Note 7) The organometallic raw material is Ba (THD) as an organometallic raw material for Ba. ₂ As Sr (THD) as an organometallic raw material for Sr ₂ And Ti (O-iPr) as an organometallic raw material for Ti ₂ (THD) ₂ 6. The method of forming a thin film according to claim 5, comprising:
[0081]
(Supplementary Note 8) The organometallic raw material is Bi (THD) ₂ And Bi (ph) ₃ Sr (THD) as one of the organometallic raw materials for Sr ₂ With Ta (OEt) as an organic metal raw material of Ta ₅ And Ta (O-iPr) ₄ 6. The thin film forming method according to claim 5, comprising one of (THD).
[0082]
(Supplementary Note 9) The organometallic raw material is Bi (THD) as an organic metal raw material of Bi. ₃ And Bi (ph) ₃ One of La (THD) as an organic metal raw material of La ₃ With Ti (O-iPr) as the organometallic raw material for Ti ₂ (THD) ₂ 6. The thin film forming method according to claim 5, comprising one of the following.
[0083]
(Supplementary Note 10) The organometallic raw material is Bi (THD) ₂ And Bi (ph) ₃ Is used as an organometallic raw material for Ti, Ti (O-iPr) ₂ (THD) ₂ 6. The thin film forming method according to claim 5, comprising:
[0084]
(Supplementary Note 11) A method of manufacturing a semiconductor device including a ferroelectric capacitor,
Forming a ferroelectric film on the lower electrode;
Forming an upper electrode on the ferroelectric film,
The step of forming the ferroelectric film,
Vaporizing the organometallic raw material dissolved in the organic solvent to form an organometallic raw material gas,
Forming the ferroelectric film on the lower electrode by decomposing the organometallic raw material gas,
The organic solvent is selected from the group consisting of 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, ethyl formate, methyl acetate and n-propylamine. A method of manufacturing a semiconductor device.
[0085]
【The invention's effect】
According to the present invention, in a film forming method including a step of vaporizing an organic metal raw material in a vaporizer, the organic metal raw material is supplied to the vaporizer with 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2 Dissolved in an organic solvent having a heat capacity per unit volume of less than 56.6 J / ml selected from the group consisting of 2,3-dimethylbutane, cyclopentane, methylal, ethyl formate, methyl acetate and n-propylamine. Thereby, the temperature rise and vaporization of the organometallic raw material in the vaporizer are performed in a short time, and the generation of particles due to the supply of the partially decomposed organometallic raw material to the reaction vessel is effectively suppressed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an MOCVD apparatus used in the present invention.
FIG. 2 is a view showing a temperature rise characteristic of a liquid raw material in a vaporizer of the MOCVD apparatus of FIG.
FIG. 3 is another diagram showing a temperature rise characteristic of a liquid raw material in a vaporizer of the MOCVD apparatus of FIG.
FIG. 4 is a diagram showing an example of an organometallic raw material used in the MOCVD apparatus of FIG.
FIG. 5 is a diagram showing a relationship between the number of particles deposited on a substrate and a heat capacity of an organic solvent used in a PZT film forming process according to a first embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of an FeRAM according to a second embodiment of the present invention.
FIGS. 7A to 7C are diagrams (part 1) illustrating the manufacturing process of the FeRAM of FIG. 6;
8 (D)-(E) are views (No. 2) showing the steps of manufacturing the FeRAM of FIG. 6;
9 (F)-(G) are views (No. 3) showing the steps of manufacturing the FeRAM of FIG. 6;
FIG. 10H is a view (part 4) showing a step of manufacturing the FeRAM of FIG. 6;
[Explanation of symbols]
10 MOCVD equipment
11 Deposition chamber
11A susceptor
11B exhaust line
12 vaporizer
12 ₁ , 12 ₂ , 12 ₃ Raw material container
12A source gas supply line
12B Bypass line
12a, 12b Valve
13 Gas mixer
13A Oxidizing gas line
14 Vacuum pump
15 Cold trap
16,26 abatement equipment
17 heating jacket
30 FeRAM
30A element isolation structure
31 Si substrate
31A, 31B Diffusion area
32 Gate insulating film
33 Gate electrode
34,35 interlayer insulating film
36 Lower capacitor electrode
37 Ferroelectric capacitor insulating film
38 Upper capacitor electrode
360 Lower electrode layer
370 Ferroelectric film
380 Upper electrode layer

Claims (10)

Vaporizing the organometallic raw material dissolved in the organic solvent to form an organometallic raw material gas,
A step of introducing the organometallic raw material gas into a processing vessel holding a substrate to be processed,
Forming a thin film on the substrate to be processed by decomposing the organometallic source gas in the processing container,
The organic solvent is selected from the group consisting of 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, ethyl formate, methyl acetate and n-propylamine. A thin film forming method. The method according to claim 1, wherein the organic solvent is selected from the group consisting of 2,2-dimethylbutane, 2,3-dimethylbutane, cyclopentane, methylal, and n-propylamine. The method according to claim 1, wherein the organic solvent is selected from the group consisting of 2,2-dimethylbutane, cyclopentane, and methylal. The method according to claim 1, wherein the organic solvent comprises cyclopentane or methylal. The method according to claim 1, wherein the organic metal material has a vaporization temperature in a range of 180 to 300C. The organometallic raw material is Pb (THD) ₂ as an organometallic raw material of Pb, Zr (DMHD) ₄ as an organometallic raw material of Zr, and Ti (O-iPr) ₂ (THD) ₂ as an organometallic raw material of Ti. 6. The method of forming a thin film according to claim 5, comprising: The organometallic raw material is Ba (THD) ₂ as an organometallic raw material of Ba, Sr (THD) ₂ as an organometallic raw material of Sr, and Ti (O-iPr) ₂ (THD) ₂ as an organometallic raw material of Ti. 6. The method of forming a thin film according to claim 5, comprising: The organometallic raw material is any one of Bi (THD) ₂ and Bi (ph) _{3 as} a Bi organic metal raw material, Sr (THD) ₂ as a Sr organic metal raw material, and Ta (Ta) as a Ta organic metal raw material. 6. The thin film forming method according to claim 5, comprising one of OEt) ₅ and Ta (O-iPr) ₄ (THD). The organometallic raw material is one of Bi (THD) ₃ and Bi (ph) _{3 as} a Bi organic metal raw material, La (THD) ₃ as a La organic metal raw material, and Ti ( The thin film forming method according to claim 5, comprising one of O-iPr) ₂ (THD) ₂ . The organic metal raw material includes one of Bi (THD) ₂ and Bi (ph) _{3 as} a Bi organic metal raw material and Ti (O-iPr) ₂ (THD) ₂ as a Ti organic metal raw material. The method for forming a thin film according to claim 5, wherein:

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