JP3627106B2 - Method for producing hafnium silicate thin film by atomic layer adsorption deposition - Google Patents
Method for producing hafnium silicate thin film by atomic layer adsorption deposition Download PDFInfo
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- JP3627106B2 JP3627106B2 JP2002191265A JP2002191265A JP3627106B2 JP 3627106 B2 JP3627106 B2 JP 3627106B2 JP 2002191265 A JP2002191265 A JP 2002191265A JP 2002191265 A JP2002191265 A JP 2002191265A JP 3627106 B2 JP3627106 B2 JP 3627106B2
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
- H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
- H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
- H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
- H01L21/0228—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
- H01L21/02142—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing silicon and at least one metal element, e.g. metal silicate based insulators or metal silicon oxynitrides
- H01L21/02148—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing silicon and at least one metal element, e.g. metal silicate based insulators or metal silicon oxynitrides the material containing hafnium, e.g. HfSiOx or HfSiON
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02205—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition
- H01L21/02208—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si
- H01L21/02211—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si the compound being a silane, e.g. disilane, methylsilane or chlorosilane
Description
【０００１】
【発明の属する技術分野】
本発明は、半導体装置のゲート絶縁膜であるハフニウムシリケート膜を製造する方法に関する。
【０００２】
【従来の技術】
半導体装置のゲート絶縁膜として、現在のところ二酸化ケイ素が主要材料として用いられている。しかし、ゲート長の微細化に伴い、ゲート絶縁膜もさらなる薄膜化が要求されている。その解決法として、二酸化ケイ素よりも高誘電率の材料が求められており、二酸化ケイ素を用いることによる限界が近づいている。
二酸化ケイ素に替わる絶縁膜材料として、二酸化ケイ素よりも高誘電率であるハフニウムシリケート、ジルコニウムシリケート、酸化ハフニウム、酸化ジルコニウム、酸化ランタン、酸化プラセオジム等が検討されている。このうちハフニウムシリケートは、高温までアモルファス状態が保たれ、膜質が良く、リークが少ない膜として最も期待されている。
【０００３】
ゲート絶縁膜の薄膜方法としては、スパッタ法、ＭＯＣＶＤ法が挙げられるが、さらなる薄膜化に応えられるものではない。この薄膜化に応える手段として、原子及び分子レベルの膜厚を制御できるＡＬＤ法が有望視されている。
ＡＬＤ法は、各原料ガスを同時ではなく交互に供給することで、ＣＶＤの素過程である各原料ガスの表面吸着と表面反応を単分子層レベルで制御して、原子層あるいは分子層を一層毎に成長させる方法である。よって、ＡＬＤ法用の原料として特に求められることは、蒸気圧が高く、分子サイズが小さく、酸素供給源やケイ素供給源と反応しやすいことが挙げられる。分子サイズが小さいと単分子層の吸着モル量が増すので、装置のスループットが上がる。
【０００４】
ＭＯＣＶＤ法ではシリコン基板上にゲート絶縁膜を堆積する際、比較的高温が必要であるため、主な酸素供給源である酸素、オゾンによってシリコン基板が酸化され、界面層が形成し、膜が厚くなってしまうという問題がある。すなわち、酸素供給剤としてオゾンや酸素を用いた場合、各原料ガスが同時供給されるために、むき出しの基板表面にオゾンが接触し、表面を酸化、界面層が形成されてしまう。よってＭＯＣＶＤ法でシリコン基板上にゲート絶縁膜を堆積する場合、酸素供給剤にオゾンや酸素を用いることは困難であり、また薄膜化も期待できない。
しかし、各原料ガスを交互供給し、各原料ガスの基板への表面吸着と表面反応を制御するＡＬＤ法では、基板表面に原料ガスを吸着させた後に酸素供給剤を供給するため、酸素供給剤が基板表面に接触せず、界面層を形成しない。ＡＬＤ法にて有望視されている酸素供給源として、水や過酸化水素、オゾン、金属アルコキシドが挙げられる。
【０００５】
一般に量産用ＡＬＤ用の原料化合物が持つべき、供給時の好ましい性質としては、分子サイズが小さく、酸素供給源である水や金属アルコキシドと容易に反応し、純品で高い蒸気圧を持ち、供給時における温度にて安定で、室温付近、少なくとも使用ソース温度で液体であることが挙げられる。
【０００６】
ＡＬＤ法ではないが、第６２回応用物理学会学術講演会予稿集１２ｐ−Ｃ−１１（２００１）では、Ｈｆ源であるテトラキス（ジエチルアミノ）ハフニウム
Ｈｆ［Ｎ（Ｃ２Ｈ３）２］４とケイ素源としてトリス（ジエチルアミノ）シランＳｉ［Ｎ（Ｃ２Ｈ５）２］３Ｈおよび酸素を用いて、ハフニウムシリケート薄膜をＭＯＣＶＤ法にて形成している。しかしＨｆ［Ｎ（Ｃ２Ｈ５）２］４の蒸気圧は、本発明者らの測定では９０℃／０．１Ｔｏｒｒで低い。また温度を上げるとシリンダー内で変質しやすいことが分かっている。さらには分子サイズが大きく、単分子層を吸着させることが求められるＡＬＤ法に好適な原料であるとは言い難い。
【０００７】
塩化ハフニウムＨｆＣｌ４は固体であり、蒸気圧が低く、また膜中に塩素が含まれるという問題がある。
【０００８】
テトラターシャリーブトキシハフニウムＨｆ（Ｏ−ｔ−Ｃ４Ｈ９）４は、蒸気圧は高いが、分子サイズが大きい。Ｃｈｅｍ．Ｖａｐ．Ｄｅｐｏｓｉｔｉｏｎ，２０００，６，２９７では、Ｈｆ（Ｏ−ｔ−Ｃ４Ｈ９）４の類似化合物であるテトラターシャリーブトキシジルコニウムＺｒ（Ｏ−ｔ−Ｃ４Ｈ９）４および水を用い、ＡＬＤ法にて酸化ジルコニウム膜を形成している。しかしＺｒ（Ｏ−ｔ−Ｃ４Ｈ９）４は、熱により自己反応が起こり、連鎖的に膜が堆積されることが明らかになっており、Ｈｆ（Ｏ−ｔ−Ｃ４Ｈ９）４も同様な現象が起きると予想される。
よって、各原料ガスの表面吸着と表面反応を単分子層レベルで制御することが求められるＡＬＤ法に好適な原料であるとは言い難い。
【０００９】
Ｃｈｅｍ．Ｍａｔｅｒ．，２００１，１３，２４６３では、テトラキス（ジメチルアミノ）ハフニウムＨｆ［Ｎ（ＣＨ３）２］４、トリス（ターシャリーブトキシ）シラノールＳｉ（Ｏ−ｔ−Ｃ４Ｈ９）３ＯＨを溶媒であるテトラデカンに溶かして、ＡＬＤ法にてハフニウムシリケート薄膜を形成している。この反応はＨｆ［Ｎ（ＣＨ３）２］４とＳｉ（Ｏ−ｔ−Ｃ４Ｈ９）３ＯＨのＡＬＤであり、水を使用していない。しかしｓｉ（Ｏ−ｔ−Ｃ４Ｈ９）３ＯＨは分子サイズが大きく、またＨｆ［Ｎ（ＣＨ３）２］４との反応性は比較的低く、且つ自己分解し、膜中に炭素が残る可能性がある。さらには溶媒を使用しているため、膜中に炭素等が残留する可能性がある。またＳｉ（Ｏ−ｔ−Ｃ４Ｈ９）３ＯＨは、融点が６５℃の固体でやや扱いにくい。
【００１０】
【発明が解決しようとする課題】
本発明は、ＡＬＤ法によるハフニウムシリケート薄膜の製造方法に関する。さらに詳しくは、ＡＬＤ法用の原料として特に求められている、蒸気圧が高く、分子サイズが小さく、酸素供給源やケイ素供給源と反応しやすい原料を提供し、且つそれを用いてＡＬＤ法にてハフニウムシリケート薄膜を製造する方法を提供することである。
【００１１】
【課題を解決するための手段】
本発明者らは、Ｈｆ［Ｎ（ＣＨ３）２］４の融点が２８℃で、金属有機化合物のうちで最も分子サイズが小さく、蒸気圧が高く、水との反応が激しいこと、ならびにＳｉ（ＯＣＨ３）４が液体で、水との反応が最も激しく、且つ分子サイズが小さく、蒸気圧が高いことを利用すれば、最も容易に生産性良く、良好なハフニウムシリケート薄膜が得られることを見いだし、本発明を完成するに至った。
【００１２】
１分子の吸着面積の指標として、分子半径から計算された投影断面積を表１に示す。
【００１３】
【表１】
表１によれば、Ｈｆ［Ｎ（ＣＨ３）２］４１分子の吸着面積は、Ｈｆ［Ｎ（Ｃ２Ｈ５）２］４やＨｆ（Ｏ−ｔ−Ｃ４Ｈ９）４の１／２である。よって、Ｈｆ［Ｎ（ＣＨ３）２］４使用時の１サイクル当たりのスループットは、他の材料の約２倍となることが分かる。
また、Ｓｉ（ＯＣＨ３）４１分子の吸着面積は、Ｓｉ（ＯＣ２Ｈ５）４やＳｉ（Ｏ−ｔ−Ｃ４Ｈ９）３ＯＨの１／２以下である。よって、Ｓｉ（ＯＣＨ３）４使用時の１サイクル当たりのスループットは、他の材料の約２倍となることが分かる。
【００１５】
上記の各化合物の蒸気圧を表２に示す。
【００１６】
【表２】
表２によれば、Ｈｆ［Ｎ（ＣＨ３）２］４とＨｆ（Ｏ−ｔ−Ｃ４Ｈ９）４はほぼ同じ温度で高い蒸気圧を持ち、２Ｔｏｒｒの圧力を与える温度は、Ｈｆ［Ｎ（Ｃ２Ｈ５）２］４よりも約７０℃も低い。よって、Ｈｆ［Ｎ（ＣＨ３）２］４は熱分解しにくい条件で供給しやすい。
また、Ｓｉ（ＯＣＨ３）４の蒸気圧も非常に高いことが分かる。
【００１８】
Ｈｆ［Ｎ（ＣＨ３）２］４は酸素供給剤である水との反応性が高い。また酸素供給源である水と反応した場合、その副生成物はジメチルアミンＮＨ（ＣＨ３）２であるため、非常に高い蒸気圧を持ち、より安定で系外に排出されやすく、膜中にＮやＣが残りにくい。
【００１９】
Ｓｉ（ＯＣＨ３）４も酸化剤である水やオゾンとの反応性が、テトラエトキシシランＳｉ（ＯＣ２Ｈ５）４やトリス（ターシャリーブトキシ）シラノールＳｉ（Ｏ−ｔ−Ｃ４Ｈ９）３ＯＨよりも高い。
【００２０】
よって、ＡＬＤ法にてハフニウムシリケート薄膜を形成する場合には、分子サイズが小さく、低温でも十分な蒸気圧を持ち、水との反応性が高い化合物である、Ｈｆ［Ｎ（ＣＨ３）２］４とＳｉ（ＯＣＨ３）４の組み合わせが最も適していることが分かる。
【００２１】
酸化剤として水を便用した場合の反応式は、以下のとおりである。
Ｈｆ［Ｎ（ＣＨ３）２］４＋Ｈ２Ｏ→Ｈｆ（ＯＨ）４
Ｈｆ（ＯＨ）４＋Ｓｉ（ＯＣＨ３）４→−ＨｆＯＳｉ（ＯＣＨ３）ｘ
−ＨｆＯＳｉ（ＯＣＨ３）ｘ＋Ｈ２Ｏ→−ＨｆＯＳｉ（ＯＨ）ｘ
−ＨｆＯＳｉ（ＯＨ）ｘ＋Ｈｆ［Ｎ（ＣＨ３）２］４→−ＨｆＯＳｉＯＨｆ［Ｎ（ＣＨ３）２］ｘ
以上の反応を繰り返すことにより、ハフニウムシリケート薄膜が形成される。
【００２２】
酸化剤としてオゾンを使用した場合の反応式は、以下のとおりである。
Ｈｆ［Ｎ（ＣＨ３）２］４＋Ｏ３→ＨｆＯ２
ＨｆＯ２＋Ｓｉ（ＯＣＨ３）４→−ＨｆＯ２・・・Ｓｉ（ＯＣＨ３）４
−ＨｆＯ２・・・Ｓｉ（ＯＣＨ３）４＋Ｏ３→−ＨｆＯＳｉＯｘ
−ＨｆＯＳｉＯｘ＋Ｈｆ［Ｎ（ＣＨ３）２］４→−ＨｆＯＳｉＯｘ・・・Ｈｆ［Ｎ（ＣＨ３）２］４
以上の反応を繰り返すことにより、ハフニウムシリケート薄膜が形成される。
【００２３】
本発明は、ＡＬＤ法によるハフニウムシリケート薄膜の製造方法において、テトラキス（ジメチルアミノ）ハフニウムとテトラメトキシシランと酸化剤を原料として用いることを特徴とするハフニウムシリケート薄膜の製造方法である。
【００２４】
本発明は、酸化剤が水であることを特徴とする上記のハフニウムシリケート薄膜の製造方法である。
【００２５】
本発明は、酸化剤がオゾンであることを特徴とする上記のハフニウムシリケート薄膜の製造方法である。
【００２６】
本発明は、順に、テトラキス（ジメチルアミノ）ハフニウム、酸化剤、テトラメトキシシラン、酸化剤を１サイクルとしてＡＬＤ室に導入することを特徴とする上記のハフニウムシリケート薄膜の製造方法である。
【００２７】
本発明は、テトラキス（ジメチルアミノ）ハフニウムの導入回数ならびにテトラメトキシシランの導入回数を任意に選択することにより、ハフニウムシリケート薄膜中のハフニウムとケイ素の比を所定の値にすることを特徴とする上記のハフニウムシリケート薄膜の製造方法である。
【００２８】
【発明の実施の形態】
本発明のＨｆ［Ｎ（ＣＨ３）２］４の供給方法としては、次の方法がある。
▲１▼ソース温度を５０〜１２０℃に保ち、発生する蒸気の自圧でベーパーソースマスフローコントローラーにより供給する。
▲２▼融点の２８℃以上、好ましくは４０℃以上にソース温度を保ち、液体とし、キャリアーガスをバブリングすることにより、Ｈｆ［Ｎ（ＣＨ３）２］４を気化させる。
▲３▼ソース温度を２８℃以上に加熱し液体として、４５℃程度に加熱された液体マスフローコントローラーで供給し、気化器で全量気化する。
【００２９】
本発明のＳｉ（ＯＣＨ３）４および水の供給方法も、Ｈｆ［Ｎ（ＣＨ３）２］４と同様な方法が使える。
【００３０】
酸素供給源としては、水、オゾンを用いることができる。特に好ましくは水である。
【００３１】
ハフニウムシリケート薄膜中のＨｆ／Ｓｉを所定の比にするには、ＨｆショットとＳｉショットの回数を適当に選べばよい。
【００３２】
ＡＬＤの基板温度は１５０〜３５０℃である。１５０℃よりも低いと反応が完全に進行せず、３５０℃以上では自己分解反応が起きるので好ましくない。好ましくは、２００〜３００℃である。ＡＬＤ室の反応は、０．００１〜１Ｔｏｒｒである。好ましくは、０．００１〜０．１Ｔｏｒｒである。
【００３３】
ＡＬＤ後に４００〜７００℃で熱処理し、膜中に存在するＣ，Ｈ，Ｎ，Ｈ２Ｏ，ＯＨなどの不純物をなくし、構造上の欠陥をなくすことが好ましい。
【００３４】
【実施例１】
水を酸素供給源としたＡＬＤ装置を図１に示した。
Ｈｆ［Ｎ（ＣＨ３）２］４を入れたシリンダー１を７６℃に加熱し、シリンダー内を純Ｈｆ［Ｎ（ＣＨ３）２］４蒸気２．０Ｔｏｒｒにし、仕込み弁を通してＡＬＤ室５へ導いた。Ｓｉ（ＯＣＨ３）４を入れたシリンダー２を２１℃に加熱し、シリンダー内を純Ｓｉ（ＯＣＨ３）４蒸気１０Ｔｏｒｒにし、仕込み弁を通してＡＬＤ室５に導いた。水を入れたシリンダー３を１２℃に加熱し、シリンダー内を純Ｈ２Ｏ蒸気１０Ｔｏｒｒにし、仕込み弁を通してＡＬＤ室５に導いた。上記、いずれの配管、弁はシリンダー温度よりも３０℃高く保ち、蒸気の凝縮を防止した。これらのガスを順次導き、２５０℃のＨＦ処理Ｓｉ基板７上に吸着反応させた。パージガスとして配管４からＡｒを導入した。ＡＬＤ室は０．０５Ｔｏｒｒに排気ポンプ６により保った。
【００３５】
そのやり方は、〔Ｈｆショット（０．５秒）→Ａｒパージ（２秒）→Ｈ２Ｏショット（０．２秒）→Ａｒパージ（２秒）→Ｓｉショット（０．５秒）→Ａｒパージ（２秒）→Ｈ２Ｏショット（０．２秒）→Ａｒパージ（２秒）〕を１サイクルとし、このサイクルを２５回繰り返したところ、約５ｎｍのハフニウムシリケート薄膜が形成された。最後に６０℃でアニールを行い、水や炭素を含まないアモルファスハフニウムシリケート膜を得た。
【００３６】
【実施例２】
オゾンを酸素供給源としたＡＬＤ装置を図２に示した。
Ｈｆ［Ｎ（ＣＨ３）２］４を入れたシリンダー１を７６℃に加熱し、シリンダー内を純Ｈｆ［Ｎ（ＣＨ３）２］４蒸気２．０Ｔｏｒｒにし、仕込み弁を通してＡＬＤ室５へ導いた。Ｓｉ（ＯＣＨ３）４を入れたシリンダー２を２１℃に加熱し、シリンダー内を純Ｓｉ（ＯＣＨ３）４蒸気１０Ｔｏｒｒにし、仕込み弁を通してＡＬＤ室５に導いた。配管８を通してオゾンを１０％含むＮ２１０Ｔｏｒｒを仕込み弁を通してＡＬＤ室へ導いた。上記、いずれの配管、弁はシリンダー温度よりも３０℃高く保ち、蒸気の凝縮を防止した。これらのガスを順次導き、２５０℃のＨＦ処理Ｓｉ基板７上に吸着反応させた。パージガスとして配管４からＡｒを導入した。ＡＬＤ室は０．０５Ｔｏｒｒに排気ポンプ６により保った。
【００３７】
そのやり方は、〔Ｈｆショット（０．５秒）→Ａｒパージ（２秒）→Ｏ３ショット（０．２秒）→Ａｒパージ（２秒）→Ｓｉショット（０．５秒）→Ａｒパージ（２秒）→Ｏ３ショット（０．２秒）→Ａｒパージ（２秒）〕を１サイクルとし、このサイクルを２５回繰り返したところ、約５ｎｍのハフニウムシリケート薄膜が形成された。最後に６００℃でアニールを行い、水や炭素を含まないアモルファスハフニウムシリケート膜を得た。
【００３８】
【発明の効果】
本発明によればゲート絶縁膜において、基板界面ＳｉＯ２を形成せず、且つ水や炭素を含まないアモルファスのハフニウムシリケート極薄膜を得ることができる。
【図面の簡単な説明】
【図１】水を酸素供給源としたＡＬＤ装置の図である。
【図２】オゾンを酸素供給源としたＡＬＤ装置の図である。
【符号の説明】
１ Ｈｆ［Ｎ（ＣＨ３）２］４を入れるシリンダー
２ Ｓｉ（ＯＣＨ３）４を入れるシリンダー
３ 水を入れるシリンダー
４ パージガスＡｒを通す配管
５ ＡＬＤ室
６ 排気ポンプ
７ Ｓｉ基板
８ Ｏ３＋Ｎ２を通す配管[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a hafnium silicate film which is a gate insulating film of a semiconductor device.
[0002]
[Prior art]
At present, silicon dioxide is used as a main material as a gate insulating film of a semiconductor device. However, with the miniaturization of the gate length, the gate insulating film is required to be further thinned. As a solution, a material having a higher dielectric constant than silicon dioxide is required, and the limit due to the use of silicon dioxide is approaching.
As an insulating film material replacing silicon dioxide, hafnium silicate, zirconium silicate, hafnium oxide, zirconium oxide, lanthanum oxide, praseodymium oxide, and the like, which have a higher dielectric constant than silicon dioxide, have been studied. Among these, hafnium silicate is most expected as a film that maintains an amorphous state up to a high temperature, has a good film quality, and has few leaks.
[0003]
Examples of the thin film method for the gate insulating film include a sputtering method and an MOCVD method, but they cannot meet the further thinning. As a means for responding to this thinning, the ALD method capable of controlling the film thickness at the atomic and molecular level is promising.
In the ALD method, by supplying each source gas alternately instead of simultaneously, the surface adsorption and surface reaction of each source gas, which is an elementary process of CVD, are controlled at the monomolecular layer level, and an atomic layer or a molecular layer is formed. It is a method of growing every time. Therefore, what is particularly required as a raw material for the ALD method is that the vapor pressure is high, the molecular size is small, and it easily reacts with an oxygen supply source or a silicon supply source. If the molecular size is small, the amount of adsorbed moles of the monomolecular layer increases, which increases the throughput of the apparatus.
[0004]
In the MOCVD method, when a gate insulating film is deposited on a silicon substrate, a relatively high temperature is required. Therefore, the silicon substrate is oxidized by oxygen and ozone which are main oxygen supply sources, an interface layer is formed, and the film is thick. There is a problem of becoming. That is, when ozone or oxygen is used as the oxygen supply agent, since the source gases are supplied simultaneously, ozone comes into contact with the exposed substrate surface, and the surface is oxidized and an interface layer is formed. Therefore, when a gate insulating film is deposited on a silicon substrate by the MOCVD method, it is difficult to use ozone or oxygen as an oxygen supply agent, and a thin film cannot be expected.
However, in the ALD method in which each source gas is supplied alternately and the surface adsorption and surface reaction of each source gas on the substrate are controlled, the oxygen supply agent is supplied after the source gas is adsorbed on the substrate surface. Does not contact the substrate surface and does not form an interface layer. Examples of oxygen sources that are considered promising in the ALD method include water, hydrogen peroxide, ozone, and metal alkoxides.
[0005]
In general, the raw material compounds for ALD for mass production should have desirable properties at the time of supply. The molecular size is small, it easily reacts with water and metal alkoxide as the oxygen supply source, and is a pure product with high vapor pressure. It is stable at the temperature at the time and is liquid at around the room temperature, at least at the source temperature used.
[0006]
Although it is not an ALD method, in the 62nd Japan Society of Applied Physics Lecture Proceedings 12p-C-11 (2001), tetrakis (diethylamino) hafnium Hf [N (C 2 H 3 ) 2 ] 4 and silicon, which are Hf sources, are used. A hafnium silicate thin film is formed by MOCVD using tris (diethylamino) silane Si [N (C 2 H 5 ) 2 ] 3 H as a source and oxygen. However, the vapor pressure of Hf [N (C 2 H 5 ) 2 ] 4 is as low as 90 ° C./0.1 Torr as measured by the inventors. It has also been found that when the temperature is raised, the material is easily altered in the cylinder. Furthermore, it is difficult to say that it is a suitable raw material for the ALD method that has a large molecular size and is required to adsorb a monolayer.
[0007]
Hafnium chloride HfCl 4 is a solid, has a low vapor pressure, and contains chlorine in the film.
[0008]
Tetratertiary butoxyhafnium Hf (Ot-C 4 H 9 ) 4 has a high vapor pressure but a large molecular size. Chem. Vap. In Deposition, 2000, 6,297, an ALD method using tetratertiary butoxyzirconium Zr (Ot-C 4 H 9 ) 4 , which is an analog of Hf (Ot-C 4 H 9 ) 4, and water. A zirconium oxide film is formed at However, it has been clarified that Zr (Ot-C 4 H 9 ) 4 undergoes a self-reaction due to heat and a film is deposited in a chain, and Hf (Ot-C 4 H 9 ) 4 A similar phenomenon is expected to occur.
Therefore, it is difficult to say that the raw material is suitable for the ALD method that requires the surface adsorption and surface reaction of each raw material gas to be controlled at the monomolecular layer level.
[0009]
Chem. Mater. , 2001, 13, 2463, tetradecane (dimethylamino) hafnium Hf [N (CH 3 ) 2 ] 4 , tris (tertiary butoxy) silanol Si (Ot-C 4 H 9 ) 3 OH as a solvent. A hafnium silicate thin film is formed by ALD method. This reaction is an ALD of Hf [N (CH 3 ) 2 ] 4 and Si (Ot-C 4 H 9 ) 3 OH and does not use water. However, si (Ot-C 4 H 9 ) 3 OH has a large molecular size, is relatively low in reactivity with Hf [N (CH 3 ) 2 ] 4 and self-decomposes, so that carbon is not present in the film. It may remain. Furthermore, since a solvent is used, carbon or the like may remain in the film. Moreover, Si (Ot-C 4 H 9 ) 3 OH is a solid with a melting point of 65 ° C. and is somewhat difficult to handle.
[0010]
[Problems to be solved by the invention]
The present invention relates to a method for producing a hafnium silicate thin film by an ALD method. More specifically, it provides a raw material that is particularly required as a raw material for the ALD method, has a high vapor pressure, a small molecular size, and easily reacts with an oxygen supply source or a silicon supply source. And providing a method for producing a hafnium silicate thin film.
[0011]
[Means for Solving the Problems]
The inventors of the present invention have a melting point of Hf [N (CH 3 ) 2 ] 4 of 28 ° C., the smallest molecular size among metal organic compounds, a high vapor pressure, and a strong reaction with water. (OCH 3 ) 4 is a liquid, the reaction with water is the most intense, the molecular size is small, and the vapor pressure is high, so that a good hafnium silicate thin film can be obtained most easily with good productivity. As a result, the present invention has been completed.
[0012]
Table 1 shows the projected cross-sectional area calculated from the molecular radius as an index of the adsorption area of one molecule.
[0013]
[Table 1]
According to Table 1, the adsorption area of one molecule of Hf [N (CH 3 ) 2 ] 4 is 1 of Hf [N (C 2 H 5 ) 2 ] 4 or Hf (Ot-C 4 H 9 ) 4 . / 2. Therefore, it can be seen that the throughput per cycle when using Hf [N (CH 3 ) 2 ] 4 is about twice that of other materials.
In addition, the adsorption area of one molecule of Si (OCH 3 ) 4 is ½ or less of Si (OC 2 H 5 ) 4 or Si (Ot—C 4 H 9 ) 3 OH. Therefore, it can be seen that the throughput per cycle when using Si (OCH 3 ) 4 is about twice that of other materials.
[0015]
Table 2 shows the vapor pressure of each compound.
[0016]
[Table 2]
According to Table 2, Hf [N (CH 3 ) 2 ] 4 and Hf (Ot-C 4 H 9 ) 4 have a high vapor pressure at almost the same temperature, and the temperature giving a pressure of 2 Torr is Hf [ N (C 2 H 5 ) 2 ] 4 is about 70 ° C. lower. Therefore, Hf [N (CH 3 ) 2 ] 4 is easy to supply under conditions that are difficult to thermally decompose.
It can also be seen that the vapor pressure of Si (OCH 3 ) 4 is very high.
[0018]
Hf [N (CH 3 ) 2 ] 4 is highly reactive with water as an oxygen supply agent. In addition, when it reacts with water, which is an oxygen supply source, the by-product is dimethylamine NH (CH 3 ) 2 , so it has a very high vapor pressure, is more stable and easily discharged out of the system, and enters the membrane. N and C are hard to remain.
[0019]
Si (OCH 3 ) 4 is also an oxidizing agent such as water and ozone. Tetraethoxysilane Si (OC 2 H 5 ) 4 and tris (tertiary butoxy) silanol Si (Ot-C 4 H 9 ) Higher than 3 OH.
[0020]
Therefore, when a hafnium silicate thin film is formed by the ALD method, Hf [N (CH 3 ) 2 ], which is a compound having a small molecular size, a sufficient vapor pressure even at a low temperature, and a high reactivity with water. It can be seen that the combination of 4 and Si (OCH 3 ) 4 is most suitable.
[0021]
The reaction formula when water is used as an oxidizing agent is as follows.
Hf [N (CH 3 ) 2 ] 4 + H 2 O → Hf (OH) 4
Hf (OH) 4 + Si (OCH 3 ) 4 → -HfOSi (OCH 3 ) x
-HfOSi (OCH 3 ) x + H 2 O → -HfOSi (OH) x
-HfOSi (OH) x + Hf [N (CH 3 ) 2 ] 4 → -HfOSiOHf [N (CH 3 ) 2 ] x
By repeating the above reaction, a hafnium silicate thin film is formed.
[0022]
The reaction formula when ozone is used as the oxidant is as follows.
Hf [N (CH 3 ) 2 ] 4 + O 3 → HfO 2
HfO 2 + Si (OCH 3 ) 4 → -HfO 2 ... Si (OCH 3 ) 4
-HfO 2 ... Si (OCH 3 ) 4 + O 3 → −HfOSiO x
−HfOSiO x + Hf [N (CH 3 ) 2 ] 4 → −HfOSiO x ... Hf [N (CH 3 ) 2 ] 4
By repeating the above reaction, a hafnium silicate thin film is formed.
[0023]
The present invention is a method for producing a hafnium silicate thin film characterized by using tetrakis (dimethylamino) hafnium, tetramethoxysilane, and an oxidizing agent as raw materials in a method for producing a hafnium silicate thin film by an ALD method.
[0024]
The present invention is the above method for producing a hafnium silicate thin film, wherein the oxidizing agent is water.
[0025]
The present invention is the above method for producing a hafnium silicate thin film, wherein the oxidizing agent is ozone.
[0026]
The present invention is the above method for producing a hafnium silicate thin film, wherein tetrakis (dimethylamino) hafnium, an oxidizing agent, tetramethoxysilane, and an oxidizing agent are sequentially introduced into the ALD chamber as one cycle.
[0027]
The present invention is characterized in that the ratio of hafnium and silicon in the hafnium silicate thin film is set to a predetermined value by arbitrarily selecting the number of introductions of tetrakis (dimethylamino) hafnium and the number of introductions of tetramethoxysilane. This is a method for producing a hafnium silicate thin film.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
The supply method of Hf [N (CH 3 ) 2 ] 4 of the present invention includes the following method.
(1) Keep the source temperature at 50 to 120 ° C., and supply with the vapor source mass flow controller with the self-pressure of the generated steam.
( 2 ) Hf [N (CH 3 ) 2 ] 4 is vaporized by maintaining the source temperature at a melting point of 28 ° C. or higher, preferably 40 ° C. or higher, and bubbling the carrier gas.
(3) The source temperature is heated to 28 ° C. or higher and supplied as a liquid by a liquid mass flow controller heated to about 45 ° C., and the whole is vaporized by a vaporizer.
[0029]
A method similar to that for Hf [N (CH 3 ) 2 ] 4 can be used as the method for supplying Si (OCH 3 ) 4 and water of the present invention.
[0030]
Water or ozone can be used as the oxygen supply source. Particularly preferred is water.
[0031]
In order to set Hf / Si in the hafnium silicate thin film to a predetermined ratio, the number of Hf shots and Si shots may be appropriately selected.
[0032]
The substrate temperature of ALD is 150-350 ° C. If it is lower than 150 ° C., the reaction does not proceed completely, and if it is 350 ° C. or higher, a self-decomposition reaction occurs, which is not preferable. Preferably, it is 200-300 degreeC. The reaction in the ALD chamber is 0.001 to 1 Torr. Preferably, it is 0.001 to 0.1 Torr.
[0033]
It is preferable to perform heat treatment at 400 to 700 ° C. after ALD to eliminate impurities such as C, H, N, H 2 O, and OH present in the film and to eliminate structural defects.
[0034]
[Example 1]
An ALD apparatus using water as an oxygen supply source is shown in FIG.
The cylinder 1 containing Hf [N (CH 3 ) 2 ] 4 is heated to 76 ° C., the inside of the cylinder is made pure Hf [N (CH 3 ) 2 ] 4 steam 2.0 Torr, and led to the
[0035]
The method is [Hf shot (0.5 sec) → Ar purge (2 sec) → H 2 O shot (0.2 sec) → Ar purge (2 sec) → Si shot (0.5 sec) → Ar purge (2 seconds) → H 2 O shot (0.2 seconds) → Ar purge (2 seconds)]. This cycle was repeated 25 times. As a result, a hafnium silicate thin film of about 5 nm was formed. Finally, annealing was performed at 60 ° C. to obtain an amorphous hafnium silicate film containing no water or carbon.
[0036]
[Example 2]
An ALD apparatus using ozone as an oxygen supply source is shown in FIG.
The cylinder 1 containing Hf [N (CH 3 ) 2 ] 4 is heated to 76 ° C., the inside of the cylinder is made pure Hf [N (CH 3 ) 2 ] 4 steam 2.0 Torr, and led to the
[0037]
The method is [Hf shot (0.5 sec) → Ar purge (2 sec) → O 3 shot (0.2 sec) → Ar purge (2 sec) → Si shot (0.5 sec) → Ar purge ( 2 seconds) → O 3 shot (0.2 seconds) → Ar purge (2 seconds)], and this cycle was repeated 25 times. As a result, a hafnium silicate thin film of about 5 nm was formed. Finally, annealing was performed at 600 ° C. to obtain an amorphous hafnium silicate film containing no water or carbon.
[0038]
【The invention's effect】
According to the present invention, it is possible to obtain an amorphous hafnium silicate ultrathin film that does not form the substrate interface SiO 2 and does not contain water or carbon in the gate insulating film.
[Brief description of the drawings]
FIG. 1 is a diagram of an ALD apparatus using water as an oxygen supply source.
FIG. 2 is a diagram of an ALD apparatus using ozone as an oxygen supply source.
[Explanation of symbols]
1 Hf [N (CH 3 ) 2 ] 4 Cylinder 2 Si (OCH 3 ) 4 Cylinder 3
Claims (5)
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| US7112485B2 (en) * | 2002-08-28 | 2006-09-26 | Micron Technology, Inc. | Systems and methods for forming zirconium and/or hafnium-containing layers |
| US6958300B2 (en) * | 2002-08-28 | 2005-10-25 | Micron Technology, Inc. | Systems and methods for forming metal oxides using metal organo-amines and metal organo-oxides |
| US7041609B2 (en) | 2002-08-28 | 2006-05-09 | Micron Technology, Inc. | Systems and methods for forming metal oxides using alcohols |
| WO2004107451A1 (en) * | 2003-05-29 | 2004-12-09 | Nec Corporation | Semiconductor device fitted with mis type field-effect transistor, process for producing the same and method of forming metal oxide film |
| JP3956225B2 (en) * | 2003-08-26 | 2007-08-08 | 株式会社トリケミカル研究所 | Film formation method |
| JP2005203730A (en) * | 2003-12-18 | 2005-07-28 | Seiko Epson Corp | Insulating film, semiconductor element, electron device, and electronic apparatus |
| JP2005191482A (en) * | 2003-12-26 | 2005-07-14 | Semiconductor Leading Edge Technologies Inc | Semiconductor device and its manufacturing method |
| JP4526995B2 (en) * | 2004-04-09 | 2010-08-18 | 東京エレクトロン株式会社 | Method for forming gate insulating film, computer-readable storage medium, and computer program |
| JP2005317583A (en) | 2004-04-27 | 2005-11-10 | Renesas Technology Corp | Semiconductor device and its manufacturing method |
| US20050252449A1 (en) * | 2004-05-12 | 2005-11-17 | Nguyen Son T | Control of gas flow and delivery to suppress the formation of particles in an MOCVD/ALD system |
| KR101304395B1 (en) * | 2004-05-12 | 2013-09-10 | 어플라이드 머티어리얼스, 인코포레이티드 | APPARATUSES AND METHODS FOR ATOMIC LAYER DEPOSITION OF HAFNIUM-CONTAINING HIGH-ｋ DIELECTRIC MATERIALS |
| US7651729B2 (en) | 2004-05-14 | 2010-01-26 | Samsung Electronics Co., Ltd. | Method of fabricating metal silicate layer using atomic layer deposition technique |
| KR100689824B1 (en) * | 2004-05-14 | 2007-03-08 | 삼성전자주식회사 | Method of manufacturing a metal silicate layer using atomic layer deposition technique |
| KR100581993B1 (en) * | 2004-06-09 | 2006-05-22 | 삼성전자주식회사 | Method of forming material using atomic layer deposition |
| KR100741983B1 (en) * | 2004-07-05 | 2007-07-23 | 삼성전자주식회사 | Semiconductor device having a gate insulating layer of a high dielectric constant and method of manufacturing the same |
| KR100640638B1 (en) | 2005-03-10 | 2006-10-31 | 삼성전자주식회사 | Method for forming high dielectric film by atomic layer deposition and method of fabricating semiconductor device having high dielectric film |
| US8034727B2 (en) | 2005-10-14 | 2011-10-11 | Nec Corporation | Method and apparatus for manufacturing semiconductor devices |
| KR100760962B1 (en) | 2006-03-14 | 2007-09-21 | 학교법인 포항공과대학교 | Ultra thin Hf-silicate film growth by atomic layer chemical vapor deposition using a new combination of precursors: metal-alkylamide and metal-alkoxide |
| US8921821B2 (en) | 2013-01-10 | 2014-12-30 | Micron Technology, Inc. | Memory cells |
| US11193206B2 (en) * | 2017-03-15 | 2021-12-07 | Versum Materials Us, Llc | Formulation for deposition of silicon doped hafnium oxide as ferroelectric materials |
| US11081337B2 (en) * | 2017-03-15 | 2021-08-03 | Versum Materials U.S., LLC | Formulation for deposition of silicon doped hafnium oxide as ferroelectric materials |
| KR102563298B1 (en) * | 2021-01-18 | 2023-08-03 | 주식회사 유진테크 | Method for removing impurities in thin film and substrate processing apparatus |
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| KR100815009B1 (en) * | 2000-09-28 | 2008-03-18 | 프레지던트 앤드 펠로우즈 오브 하바드 칼리지 | Vapor deposition of oxides, silicates, and phosphates |
| US7005392B2 (en) * | 2001-03-30 | 2006-02-28 | Advanced Technology Materials, Inc. | Source reagent compositions for CVD formation of gate dielectric thin films using amide precursors and method of using same |
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| JP2003124460A (en) * | 2001-10-15 | 2003-04-25 | Atsushi Ogura | Gate oxide film, element, and method and material for forming gate oxide film |
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