JP4259000B2 - Dielectric thin film forming solution raw material and dielectric thin film forming method using the raw material. - Google Patents
Dielectric thin film forming solution raw material and dielectric thin film forming method using the raw material. Download PDFInfo
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- JP4259000B2 JP4259000B2 JP2001194037A JP2001194037A JP4259000B2 JP 4259000 B2 JP4259000 B2 JP 4259000B2 JP 2001194037 A JP2001194037 A JP 2001194037A JP 2001194037 A JP2001194037 A JP 2001194037A JP 4259000 B2 JP4259000 B2 JP 4259000B2
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- 239000002994 raw material Substances 0.000 title claims description 90
- 239000010409 thin film Substances 0.000 title claims description 75
- 238000000034 method Methods 0.000 title claims description 24
- 229910052751 metal Inorganic materials 0.000 claims description 40
- 239000002184 metal Substances 0.000 claims description 40
- 150000002902 organometallic compounds Chemical class 0.000 claims description 28
- 239000000758 substrate Substances 0.000 claims description 23
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 20
- 230000008016 vaporization Effects 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 230000015572 biosynthetic process Effects 0.000 claims description 17
- 239000010936 titanium Substances 0.000 claims description 15
- 238000009834 vaporization Methods 0.000 claims description 15
- 239000000654 additive Substances 0.000 claims description 12
- 230000000996 additive effect Effects 0.000 claims description 12
- 239000003960 organic solvent Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 9
- 238000005229 chemical vapour deposition Methods 0.000 claims description 8
- 150000002736 metal compounds Chemical class 0.000 claims description 8
- 229910052719 titanium Inorganic materials 0.000 claims description 8
- 229910052788 barium Inorganic materials 0.000 claims description 7
- 229910052712 strontium Inorganic materials 0.000 claims description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 6
- 239000002131 composite material Substances 0.000 claims description 5
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 4
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 4
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 3
- 229910052454 barium strontium titanate Inorganic materials 0.000 claims description 2
- 239000002243 precursor Substances 0.000 claims description 2
- 239000010408 film Substances 0.000 description 36
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 17
- GMKMEZVLHJARHF-UHFFFAOYSA-N 2,6-diaminopimelic acid Chemical compound OC(=O)C(N)CCCC(N)C(O)=O GMKMEZVLHJARHF-UHFFFAOYSA-N 0.000 description 16
- 239000000203 mixture Substances 0.000 description 11
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- 238000006116 polymerization reaction Methods 0.000 description 3
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- YRAJNWYBUCUFBD-UHFFFAOYSA-N 2,2,6,6-tetramethylheptane-3,5-dione Chemical compound CC(C)(C)C(=O)CC(=O)C(C)(C)C YRAJNWYBUCUFBD-UHFFFAOYSA-N 0.000 description 2
- OISVCGZHLKNMSJ-UHFFFAOYSA-N 2,6-dimethylpyridine Chemical compound CC1=CC=CC(C)=N1 OISVCGZHLKNMSJ-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
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- YRKCREAYFQTBPV-UHFFFAOYSA-N acetylacetone Chemical compound CC(=O)CC(C)=O YRKCREAYFQTBPV-UHFFFAOYSA-N 0.000 description 2
- 125000003545 alkoxy group Chemical group 0.000 description 2
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 2
- 229910002113 barium titanate Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
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- 238000002156 mixing Methods 0.000 description 2
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 2
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- VEALVRVVWBQVSL-UHFFFAOYSA-N strontium titanate Chemical compound [Sr+2].[O-][Ti]([O-])=O VEALVRVVWBQVSL-UHFFFAOYSA-N 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- FTTQCEGWFGHNDU-UHFFFAOYSA-N 1,1,1,2,2-pentafluoro-6,6-dimethylheptane-3,5-dione Chemical compound CC(C)(C)C(=O)CC(=O)C(F)(F)C(F)(F)F FTTQCEGWFGHNDU-UHFFFAOYSA-N 0.000 description 1
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 description 1
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- FIPWRIJSWJWJAI-UHFFFAOYSA-N Butyl carbitol 6-propylpiperonyl ether Chemical compound C1=C(CCC)C(COCCOCCOCCCC)=CC2=C1OCO2 FIPWRIJSWJWJAI-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- NHTMVDHEPJAVLT-UHFFFAOYSA-N Isooctane Chemical compound CC(C)CC(C)(C)C NHTMVDHEPJAVLT-UHFFFAOYSA-N 0.000 description 1
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical class CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- WOIHABYNKOEWFG-UHFFFAOYSA-N [Sr].[Ba] Chemical compound [Sr].[Ba] WOIHABYNKOEWFG-UHFFFAOYSA-N 0.000 description 1
- NSXCBNDGHHHVKT-UHFFFAOYSA-N [Ti].[Sr].[Ba] Chemical compound [Ti].[Sr].[Ba] NSXCBNDGHHHVKT-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
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- 229940072049 amyl acetate Drugs 0.000 description 1
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- 125000004429 atom Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- 238000010504 bond cleavage reaction Methods 0.000 description 1
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- JVSWJIKNEAIKJW-UHFFFAOYSA-N dimethyl-hexane Natural products CCCCCC(C)C JVSWJIKNEAIKJW-UHFFFAOYSA-N 0.000 description 1
- HPYNZHMRTTWQTB-UHFFFAOYSA-N dimethylpyridine Natural products CC1=CC=CN=C1C HPYNZHMRTTWQTB-UHFFFAOYSA-N 0.000 description 1
- NKZSPGSOXYXWQA-UHFFFAOYSA-N dioxido(oxo)titanium;lead(2+) Chemical compound [Pb+2].[O-][Ti]([O-])=O NKZSPGSOXYXWQA-UHFFFAOYSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- MNWFXJYAOYHMED-UHFFFAOYSA-M heptanoate Chemical compound CCCCCCC([O-])=O MNWFXJYAOYHMED-UHFFFAOYSA-M 0.000 description 1
- QAMFBRUWYYMMGJ-UHFFFAOYSA-N hexafluoroacetylacetone Chemical compound FC(F)(F)C(=O)CC(=O)C(F)(F)F QAMFBRUWYYMMGJ-UHFFFAOYSA-N 0.000 description 1
- FUZZWVXGSFPDMH-UHFFFAOYSA-M hexanoate Chemical compound CCCCCC([O-])=O FUZZWVXGSFPDMH-UHFFFAOYSA-M 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
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- 125000002524 organometallic group Chemical group 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-O oxonium Chemical compound [OH3+] XLYOFNOQVPJJNP-UHFFFAOYSA-O 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
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- 229960005235 piperonyl butoxide Drugs 0.000 description 1
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- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
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- Formation Of Insulating Films (AREA)
- Semiconductor Memories (AREA)
- Inorganic Insulating Materials (AREA)
- Chemical Vapour Deposition (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、ＤＲＡＭ（Dynamic Random Access Memory）等の誘電体メモリー、誘電体フィルター等に用いられる複合酸化物系誘電体薄膜を有機金属化学蒸着法（Metal Organic Chemical Vapor Deposition、以下、ＭＯＣＶＤ法という。）により形成するための誘電体薄膜形成用溶液原料に関する。更に詳しくは、形成した膜の成膜再現性を向上し、かつ表面モフォロジーを安定化させる誘電体薄膜形成用溶液原料に関するものである。
【０００２】
【従来の技術】
近年、半導体におけるＤＲＡＭ等のメモリーデバイスの高速化、低消費電力化、低コスト化等の目的のため高集積化が急速に進んでいる。しかし、いかに集積度が向上しても、ＤＲＡＭ等の構成要素であるキャパシタは、一定の容量をもたなくてはならない。メモリーデバイスの集積度が急ピッチで増大するにつれて、キャパシタとして用いられる誘電体薄膜の膜厚を薄くする必要があり、従来のＳｉＯ2では薄膜化と同時に一定の容量を確保するのが難しくなりつつある。そこで材料を変更して誘電率を上げることができれば、薄膜化と同様に容量を確保することができるため、高誘電率の誘電体材料をメモリーデバイス用キャパシタの誘電体膜として利用するための研究が最近注目を集めている。このようなメモリー用キャパシタ材料に要求される性能としては、前述のように高誘電率を有する薄膜であること、およびリーク電流が小さいことが最も重要である。即ち、高誘電率材料を用いる限りにおいては、できる限り薄い膜で、かつ、リーク電流を最小にする必要がある。
【０００３】
このような観点から、より誘電率の高い２種以上の金属を含有する酸化物からなる複合酸化物系の誘電体材料の使用が検討されている。かかる誘電体材料の例としては、チタン酸鉛（ＰＴ）、チタン酸ジルコン酸鉛（ＰＺＴ）、チタン酸ジルコン酸ランタン鉛（ＰＬＺＴ）、チタン酸ストロンチウム（ＳＴ）、チタン酸バリウム（ＢＴ）、チタン酸バリウムストロンチウム（ＢＳＴ）等が挙げられる。
誘電体薄膜の原料となる有機金属化合物としては、ジピバロイルメタン（(ＣＨ3)3ＣＣＯＣＨ2ＣＯＣ(ＣＨ3)3、以下ｄｐｍという。）等のβ-ジケトン化合物を配位子とする有機金属錯体や［Ｚｒ(Ｏ-ｔ-Ｂｕ)4］等の金属アルコキシドが一般に使用されている。Ｔｉ、Ｚｒ、Ｔａ等の金属原料には金属アルコキシドとβ-ジケトナト錯体の両方が使用され、ＳｒやＢａの金属原料としては主にβ-ジケトナト錯体が使用される。
【０００４】
β-ジケトナト錯体は、一般に空気中の水分や炭酸ガスの影響を受けて劣化し易い。また、保存中にオリゴマーを形成して分子量が大きくなるなどして蒸発温度が高くなる等、変質し易い。例えばｄｐｍは代表的なβ-ジケトン化合物であるが、その金属錯体である［Ｂａ(ｄｐｍ)2］や［Ｓｒ(ｄｐｍ)2］は、これらを保存する際にデシケータ中に保存する等の注意を払っても、ＴＧ（Thermogravimetry；熱重量測定）に変化が認められる等、極めて不安定なものである。従って、β-ジケトナト錯体は、保存状態や取扱い時に劣化するのを防止するために細心の注意を必要とするものであり、原料として操作性が劣るものであった。
そのため、原料である有機金属化合物の劣化を抑制する手段として、有機金属化合物の純度を上げることにより、長期保存安定性を図ってきた。
【０００５】
複合酸化物系誘電体薄膜の形成方法については、金属アルコキシド原料をスピンコートにより基板上に成膜するゾルゲル法がこれまで盛んに研究されてきた。ゾルゲル法は、金属成分を気化させないため、膜の組成制御は容易である。しかし、ＤＲＡＭのキャパシタ用電極は段差があり、集積度が高くなるほど段差が大きく、かつ複雑になるので、スピンコート法では基板となる電極上に均一に誘電体薄膜を形成することが難しい。そのため、ここ数年は、デバイスの高集積度を見越して、段差被覆性（＝ステップカバレッジ性、段差のある複雑形状の表面への付き回り性）に優れたＭＯＣＶＤ法により誘電体薄膜を形成する研究が活性化してきた。
【０００６】
ＭＯＣＶＤ法は、各種金属の原料となる有機金属化合物を減圧下で加熱して気化させ、その蒸気を成膜室に輸送して基板上で熱分解させることにより、生成した金属酸化物を基板上に付着させる方法である。ＭＯＣＶＤ法は、他の膜製造方法に比べて段差被覆性に優れているため一般的に行われている。
このＭＯＣＶＤ法による誘電体薄膜の形成において、当初は、原料の有機金属化合物をそのまま加熱して気化させ、発生した蒸気を成膜室に送って成膜させていた。しかし、有機金属化合物原料、特にＭＯＣＶＤ法に推奨されているｄｐｍ錯体のような化合物は長期保存安定性や気化特性が良好でなく、低温での加熱によってＣＶＤ反応部へ原料を安定に輸送することは不可能であった。また、原料の気化効率を上げるために高い温度で加熱すると、原料が成膜室に達する前に熱分解しながら輸送されてしまい、膜の結晶性不良や組成ズレを生じていた。従って、有機金属化合物原料を成膜室に安定して輸送することが困難であり、高価な原料が一回の成膜ごとに使い捨てになり、また膜の組成制御が困難で、良好な誘電特性を有する誘電体膜の形成ができないという問題もあった。また、この方法では気化速度を抑えて合成（反応）時間を長くした場合には、原料の安定性が経時的に劣化して徐々に気化性が低下してくるために、形成された膜の厚さ方向の組成が不均質になってリーク電流が増大することが避けられなかった。
【０００７】
このような上記問題点を解決する方法として、原料の有機金属化合物を安定して成膜室に供給できる溶液気化ＣＶＤ法が現在広く用いられている。この溶液気化ＣＶＤ法はＭＯＣＶＤ法の改良であり、固体のＣＶＤ原料を各種有機溶媒に溶解し、液体としてＣＶＤ装置に供給する方法である。
【０００８】
【発明が解決しようとする課題】
しかし、原料の有機金属化合物を高純度化することにより溶液原料の長期保存安定性を図る効果は得られたが、ＭＯＣＶＤ法によりこの高純度化した原料を用いて基板上に誘電体薄膜を形成した場合、材料ロット間での膜質等のばらつきや、図３〜図５に示すように、基板１のトレンチやホール底部のみに薄膜２が形成されたり、膜表面での著しい粒成長が起こる、いわゆる膜の異常成長が見られるようになった。なお、図３はトレンチ底部に薄膜が形成されず、トレンチ以外で形成した薄膜が異常成長した図、図４はトレンチ底部に形成された薄膜が異常成長した図、図５はトレンチの上部にこのトレンチを覆うように薄膜が異常成長した図である。
【０００９】
本発明の目的は、形成した誘電体薄膜の成膜再現性を向上し、かつ表面モフォロジーを安定化し得る誘電体薄膜形成用溶液原料を提供することにある。
【００１０】
【課題を解決するための手段】
請求項１に係る発明は、有機金属化合物原料と、テトラヒドロフラン（以下、ＴＨＦという。）からなる有機溶媒とを混合してなる原料液に添加剤として水を１０〜２００ｐｐｍ含む誘電体薄膜形成用溶液原料であって、有機金属化合物がビス（ジピバロイルメタナト）バリウム錯体、ビス（ジピバロイルメタナト）ストロンチウム錯体及びビスイソプロポキシビスジビバロイルメタナートチタン錯体からなることを特徴とする誘電体薄膜形成用溶液原料である。
請求項１に係る発明では、有機金属化合物原料を有機溶媒に溶解した原料液に添加剤として水を１０〜２００ｐｐｍ含むことにより、この水が有機金属化合物の分子内及び分子間相互作用を抑制するため、この溶液原料を用いて形成した誘電体薄膜は、成膜再現性が良く、表面モフォロジーが安定化される。水の添加量は１０〜２００ｐｐｍである。好ましくは９０〜１５０ｐｐｍである。添加量が下限値未満であると、有機金属化合物の分子内及び分子間相互作用を抑制できず、成膜再現性の向上や、表面モフォロジーの安定化等の効果が現れない。添加量が上限値を越えると、形成する薄膜が異常成長を起こす。
【００１２】
請求項２に係る発明は、図２に示すように、請求項１記載の溶液原料を用いて有機金属化学蒸着法により基板１３上に複合酸化物型の誘電体薄膜１５を形成する方法である。
請求項３に係る発明は、請求項２に係る発明であって、有機金属化学蒸着法による誘電体薄膜の形成を溶液原料を液体状態で気化室に供給することにより行う方法である。
請求項４に係る発明は、請求項３に係る発明であって、金属ごとに別々の溶液原料を気化室に供給する方法である。
請求項２ないし４いずれかに係る発明では、請求項１記載の溶液原料を用いてＭＯＣＶＤ法により基板上に複合酸化物型の誘電体薄膜を形成することにより成膜再現性が良く、表面モフォロジーが安定化した誘電体薄膜が得られる。
【００１３】
請求項５に係る発明は、請求項２ないし４いずれか記載の方法により基板上に形成されたチタン酸バリウムストロンチウムからなる誘電体薄膜である。
【００１４】
【発明の実施の形態】
次に本発明の実施の形態について説明する。
本発明に係る溶液原料により形成することができる複合酸化物系の誘電体薄膜としては、チタン酸バリウムストロンチウム（ＢＳＴ）である。
【００１５】
ＢＳＴ薄膜の場合、Ｔｉ、Ｂａ及びＳｒの各有機金属化合物を原料として使用する。
【００１６】
有機金属化合物原料は、気化性があって、加熱により熱分解し、酸化剤（酸素）を導入することで酸化物に容易に変化するものを使用する。かかる有機金属化合物は一般に、金属原子が酸素原子を介して有機基と結合した構造をもつ化合物である。この種の好ましい化合物の例としては、金属アルコキシド、金属β-ジケトナト錯体、金属アルコキシドとβ-ジケトナト錯体の混合物等が挙げられる。β-ジケトナト錯体の例には、アセチルアセトン、ヘキサフルオロアセチルアセトン、ｄｐｍ、ペンタフルオロプロパノイルピバロイルメタン等のβ-ジケトン類を配位子とする金属錯体がある。この中で好ましいのはｄｐｍとの錯体である。金属アルコキシドとしては、アルコキシ基の炭素数が１〜６のものが好ましく、特に分岐アルコキシ基を有するもの（イソプロポキシド、tert-ブトキシド等）が好ましい。特に好ましい有機金属化合物は、金属のジピバロイルメタナト錯体、金属イソプロポキシド、金属tert-ブトキシド、金属イソプロポキシドとジピバロイルメタナト錯体の混合物、金属tert-ブトキシドとジピバロイルメタナト錯体の混合物である。アルカリ土類金属、アルカリ金属、Ｐｂについては、β-ジケトナト錯体（例えば、ジピバロイルメタナト錯体）の使用が好ましく、Ｔｉ、Ｚｒ、Ｖ、Ｎｂ等の遷移金属については、一般にβ-ジケトナト錯体と金属アルコキシドのどちらも使用可能であり、金属アルコキシドとβ-ジケトナト錯体の混合物を用いることもできる。
【００１７】
ＢＳＴ薄膜の成膜原料としては、Ｂａ及びＳｒのジピバロイルメタナト錯体と、イソプロポキシド、tert-ブトキシド、ジピバロイルメタナト錯体、イソプロポキシドとジピバロイルメタナト錯体の混合物及びtert-ブトキシドとジピバロイルメタナト錯体の混合物から選ばれたＴｉ化合物を使用することが好ましい。
【００１８】
有機溶媒は、ＴＨＦ、メチルテトラヒドロフラン、ｎ-オクタン、イソオクタン、ヘキサン、シクロヘキサン、ピリジン、ルチジン、酢酸ブチル及び酢酸アミルからなる群より選ばれた１種又は２種以上が挙げられる。好ましくはＴＨＦである。
【００１９】
本発明の誘電体薄膜形成用溶液原料は、１種又は２種以上の有機金属化合物原料と、有機溶媒とを混合してなる原料液に添加剤として水を１０〜２００ｐｐｍ含むことを特徴とする。
【００２０】
例えば、有機金属化合物として［Ｂａ(ｄｐｍ)2］と、有機溶媒としてＴＨＦとを混合して有機金属化合物を有機溶媒に溶解した原料液は、［Ｂａ(ｄｐｍ)2］中の金属元素Ｂａが電子論的にα軌道が空の状態となっているため、有機金属化合物分子内で金属Ｂａと配位子ｄｐｍとが結合の開裂を生じ（分子内開裂）、更に分子間で金属Ｂａと配位子ｄｐｍ間での重合を生じ、多量化される。多量化されたオリゴマーは熱的に不安定となるため、ＣＶＤ装置の気化室で気化される際は、加熱されて不確定な小分子と有機化合物とに分かれ、成膜室には小分子と一部オリゴマーとなった分子が同時に供給されることになる。従って、基板上に形成される誘電体薄膜は、サブミクロン単位の段差被覆面では、成膜再現性がなく、かつ表面荒れが生じてモフォロジーの異常を生じる。
【００２１】
この原料液に添加剤として水を１０〜２００ｐｐｍ含ませることにより、水は金属Ｂａへの配位性があるため、金属元素の空のα軌道上にトラップ効果をもたらし、分子間の重合体形成を抑制するため、薄膜形成時における安定した気化性を保ち、形成した誘電体薄膜の成膜再現性を向上させ、薄膜表面のモフォロジーの安定化が得られる。Ｂａを含む有機金属化合物を一例として説明したが、Ｓｒを含む有機金属化合物（例えば［Ｓｒ(ｄｐｍ)2］）についても同様の配位安定化効果が得られる。
【００２２】
また、Ｔｉを含む有機金属化合物（例えば［Ｔｉ(Ｏ-ｉ-Ｐｒ)2(ｄｐｍ)2］）の場合は、水によりオキソニウム錯体への重合を生じ、Ｔｉ化合物の水酸基錯体への移行、配位状態、ＯＨ付加体への変化等が起こるため、重合後のＴｉ錯体の方が、安定性が増し、基板への立体障害、密着性が程良く、ＴｉＯ2の初期成長がコンホーマルかつ容易に起こる。更に、金属Ｔｉに対する効果は金属Ｓｒ、金属Ｂａの配位安定化効果との相乗効果があるものと考えられる。
【００２３】
本発明の溶液原料の調製方法としては、有機溶媒に、誘電体薄膜を構成する各金属元素を含有する２種以上の有機金属化合物を一緒に、または別々に溶解させ、更に添加剤として水を１０〜２００ｐｐｍ含ませて、ＭＯＣＶＤ法による誘電体薄膜の形成に用いる溶液原料を調製する。この溶液原料を用いてＭＯＣＶＤ法により誘電体薄膜を基板又は他の基体上に形成する。本実施の形態では、ＭＯＣＶＤ法には、各溶液を加熱された気化室に供給し、ここで各溶液原料を瞬時に気化させ、成膜室に送る溶液気化ＣＶＤ法を用いる。
【００２４】
図２に示すように、ＭＯＣＶＤ装置は、チャンバ１０と蒸気発生装置１１を備える。チャンバ１０の内部にはヒータ１２が設けられ、ヒータ１２上には基板１３が保持される。このチャンバ１０の内部は圧力計１４及びニードルバルブ１６を備える配管１７により真空引きされる。蒸気発生装置１１は原料容器１８を備え、この原料容器１８は有機金属化合物を有機溶媒に溶解し、更に添加剤を含ませた溶液原料を貯蔵する。原料容器１８にはガス流量調節装置１９を介してキャリアガス導入管２１が接続され、また原料容器１８には供給管２２が接続される。供給管２２にはニードルバルブ２３及び溶液流量調節装置２４が設けられ、供給管２２は気化室２６に接続される。気化室２６にはニードルバルブ３１、ガス流量調節装置２８を介してキャリアガス導入管２９が接続される。気化室２６は更に配管２７によりチャンバ１０に接続される。
この装置では、Ｎ2、Ｈｅ、Ａｒ等の不活性ガスからなるキャリアガスがキャリアガス導入管２１から原料容器１８内に導入され、原料容器１８に貯蔵されている溶液原料を供給管２２により気化室２６に搬送する。気化室２６で気化されて蒸気となった有機金属化合物は、更にキャリアガス導入管２８から気化室２６へ導入されたキャリアガスにより配管２７を経てチャンバ１０内に供給される。チャンバ１０内において、原料有機金属化合物の蒸気を熱分解させ、これにより生成した金属酸化物を加熱された基板１３上に堆積させて誘電体薄膜を形成する。
【００２５】
本発明の溶液原料は、溶液状態の各原料化合物の気化性が安定しており、成膜された薄膜の金属原子比は溶液中の金属原子比とほぼ一致するので、安定して所定組成の複合酸化物系誘電体薄膜を成膜することができ、膜の品質が安定する。
【００２６】
本発明の溶液原料を用いてＭＯＣＶＤ法により形成された誘電体薄膜は、ＤＲＡＭのキャパシタとして有用である。ＭＯＣＶＤ法は一般に段差被覆性に優れているが、本発明の溶液原料を使用すると、従来の溶液原料を用いて形成した薄膜に比べて成膜再現性が向上し、表面モフォロジーも安定化する。
また、本発明の溶液原料は前述したように各原料化合物の蒸気を安定して成膜室に供給することができるため膜の組成制御性に優れており、所望の組成及び誘電特性を有する誘電体薄膜を安定して基板上に形成することができる。本発明の溶液原料を用いて形成された誘電体薄膜は、誘電体フィルターとして圧電共振子や赤外線センサー等に利用することもできる。
【００２７】
【実施例】
次に本発明の実施例を比較例とともに説明する。
＜実施例１＞
先ず、有機バリウム化合物としてビス（ジピバロイルメタナト）バリウム錯体［Ｂａ(ｄｐｍ)2］、有機ストロンチウム化合物としてビス（ジピバロイルメタナト）ストロンチウム錯体［Ｓｒ(ｄｐｍ)2］及び有機チタン化合物としてビスイソプロポキシビスジビバロイルメタナートチタン錯体［Ｔｉ(Ｏ-ｉ-Ｐｒ)2(ｄｐｍ)2］をそれぞれ用意した。また、有機溶媒としてＴＨＦを、添加剤として水を用意した。
次に各有機金属化合物原料とＴＨＦとを混合してＴＨＦに各有機金属化合物原料を溶解させた原料液を作製し、更に、この原料液に水を１００ｐｐｍ加えることによりＢＳＴ誘電体薄膜用溶液原料を調製した。
【００２８】
＜実施例２＞
水の添加量を２００ｐｐｍとした以外は実施例１と同様にしてＢＳＴ誘電体薄膜用溶液原料を調製した。
【００２９】
＜比較例１＞
添加剤を加えない以外は実施例１と同様にしてＢＳＴ誘電体薄膜用溶液原料を調製した。
＜比較例２＞
水の添加量を５ｐｐｍとした以外は実施例１と同様にしてＢＳＴ誘電体薄膜用溶液原料を調製した。
＜比較例３＞
水の添加量を２１０ｐｐｍとした以外は実施例１と同様にしてＢＳＴ誘電体薄膜用溶液原料を調製した。
【００３０】
＜比較評価＞
実施例１〜２及び比較例１〜３で調製したＢＳＴ誘電体薄膜用溶液原料をそれぞれ２つに分け、図２に示すようなＭＯＣＶＤ装置に導入し、基板上にＢＳＴ誘電体薄膜をそれぞれ２種類づつ形成した。同じ原料で２種類づつ形成したＢＳＴ誘電体薄膜の成膜再現性を原子間力顕微鏡（Atomic Force Microscope：ＡＦＭ）や走査型トンネル顕微鏡（Scanning Tunneling Microscope、以下、ＳＴＭという。）等により基板表面に形成した薄膜の膜質について測定した。また形成した誘電体薄膜の表面をそれぞれ観察し、表面モフォロジーを調べた。
実施例１〜２及び比較例１〜３のＢＳＴ誘電体薄膜用溶液原料の長期保存安定性、形成した誘電体薄膜の成膜再現性及び表面モフォロジーを表１にそれぞれ示す。
【００３１】
【表１】
表１より明らかなように、添加剤を含まない溶液原料を用いた比較例１では成膜再現性が悪く、表面モフォロジーも安定していない。また、添加剤である水の添加量が本発明の範囲外である比較例２及び３では、図３〜図５に示すように、膜質にばらつきが見られ、トレンチ底部のみに膜が形成されたり、トレンチ以外での薄膜が異常成長したりして、表面モフォロジーも安定していなかった。これに対して実施例１及び２では、図１に示すように、本発明の溶液原料を用いて形成された誘電体薄膜は、成膜再現性が良く、表面モフォロジーも安定化していることが判る。
【００３３】
【発明の効果】
以上述べたように、本発明の誘電体薄膜形成用溶液原料は、有機金属化合物原料と、テトラヒドロフランからなる有機溶媒とを混合してなる原料液に添加剤として水を１０〜２００ｐｐｍ含む誘電体薄膜形成用溶液原料であって、有機金属化合物がビス（ジピバロイルメタナト）バリウム錯体、ビス（ジピバロイルメタナト）ストロンチウム錯体及びビスイソプロポキシビスジビバロイルメタナートチタン錯体からなることにより、この水が有機金属化合物の分子内及び分子間相互作用を抑制するため、この溶液原料を用いて形成した誘電体薄膜の成膜再現性を向上し、かつ表面モフォロジーを安定化される。
【図面の簡単な説明】
【図１】本発明の誘電体薄膜形成用溶液原料を用いて基板上に形成された誘電体薄膜のトレンチ周辺の表面モフォロジーを示す図。
【図２】ＭＯＣＶＤ装置の概略図。
【図３】従来の誘電体薄膜形成用溶液原料を用いて基板上に形成された誘電体薄膜のトレンチ周辺の表面モフォロジーを示す図。
【図４】従来の別の誘電体薄膜形成用溶液原料を用いて基板上に形成された誘電体薄膜のトレンチ周辺の表面モフォロジーを示す図。
【図５】従来の更に別の誘電体薄膜形成用溶液原料を用いて基板上に形成された誘電体薄膜のトレンチ周辺の表面モフォロジーを示す図。
【符号の説明】
１３ 基板
１５ 誘電体薄膜[0001]
BACKGROUND OF THE INVENTION
In the present invention, a complex oxide dielectric thin film used for a dielectric memory such as a DRAM (Dynamic Random Access Memory) or a dielectric filter is referred to as a metal organic chemical vapor deposition (hereinafter referred to as MOCVD). ) Is a solution raw material for forming a dielectric thin film. More specifically, the present invention relates to a solution raw material for forming a dielectric thin film that improves the reproducibility of the formed film and stabilizes the surface morphology.
[0002]
[Prior art]
In recent years, high integration has been progressing rapidly for the purpose of increasing the speed, lowering power consumption, and reducing the cost of memory devices such as DRAMs in semiconductors. However, no matter how much the degree of integration is improved, a capacitor, which is a component such as a DRAM, must have a certain capacity. As the degree of integration of memory devices increases at a rapid pace, it is necessary to reduce the thickness of the dielectric thin film used as a capacitor. With conventional SiO 2 , it is difficult to ensure a certain capacity at the same time as the film thickness is reduced. is there. Therefore, if the dielectric constant can be increased by changing the material, it is possible to secure the same capacity as in the case of thinning. Therefore, research on the use of dielectric materials with a high dielectric constant as the dielectric film of capacitors for memory devices. Has recently attracted attention. As performance required for such a memory capacitor material, it is most important that the thin film has a high dielectric constant as described above and that the leakage current is small. That is, as long as a high dielectric constant material is used, it is necessary to make the film as thin as possible and minimize the leakage current.
[0003]
From this point of view, use of a composite oxide-based dielectric material made of an oxide containing two or more metals having a higher dielectric constant has been studied. Examples of such dielectric materials include lead titanate (PT), lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), strontium titanate (ST), barium titanate (BT), titanium And barium strontium acid (BST).
As an organic metal compound used as a raw material for the dielectric thin film, a β-diketone compound such as dipivaloylmethane ((CH 3 ) 3 CCOCH 2 COC (CH 3 ) 3 , hereinafter referred to as dpm) is used as a ligand. Organometallic complexes and metal alkoxides such as [Zr (Ot-Bu) 4 ] are generally used. Both metal alkoxides and β-diketonato complexes are used for metal raw materials such as Ti, Zr, and Ta, and β-diketonato complexes are mainly used as metal raw materials for Sr and Ba.
[0004]
β-diketonato complexes are generally susceptible to deterioration under the influence of moisture and carbon dioxide in the air. In addition, it tends to be altered, for example, an oligomer is formed during storage, the molecular weight is increased, and the evaporation temperature is increased. For example, although dpm is a typical β-diketone compound, its metal complexes [Ba (dpm) 2 ] and [Sr (dpm) 2 ] are stored in a desiccator when they are stored. Even if it is paid, a change is observed in TG (Thermogravimetry), and it is extremely unstable. Accordingly, the β-diketonato complex requires careful attention to prevent deterioration during storage and handling, and has poor operability as a raw material.
Therefore, long-term storage stability has been achieved by increasing the purity of the organometallic compound as a means for suppressing deterioration of the organometallic compound as a raw material.
[0005]
As a method of forming a complex oxide dielectric thin film, a sol-gel method in which a metal alkoxide raw material is formed on a substrate by spin coating has been actively studied so far. In the sol-gel method, the composition of the film is easy to control because the metal component is not vaporized. However, DRAM capacitor electrodes have a step, and the higher the degree of integration, the larger the step and the more complicated. Therefore, it is difficult to form a dielectric thin film uniformly on the electrode serving as a substrate by the spin coating method. Therefore, in the past few years, in anticipation of high device integration, a dielectric thin film is formed by the MOCVD method which has excellent step coverage (= step coverage, coverage to a complicated surface with steps). Research has been activated.
[0006]
The MOCVD method heats and vaporizes organometallic compounds, which are raw materials for various metals, under reduced pressure, transports the vapor to a film formation chamber, and thermally decomposes the resulting metal oxide on the substrate. It is the method of attaching to. The MOCVD method is generally performed because it has excellent step coverage as compared with other film manufacturing methods.
In the formation of the dielectric thin film by this MOCVD method, the raw material organometallic compound was initially heated and vaporized as it was, and the generated vapor was sent to the film forming chamber to form a film. However, organometallic compound raw materials, especially compounds such as dpm complexes recommended for MOCVD, do not have good long-term storage stability and vaporization characteristics, and can stably transport the raw materials to the CVD reaction section by heating at low temperatures. Was impossible. Further, if heating is performed at a high temperature in order to increase the vaporization efficiency of the raw material, the raw material is transported while thermally decomposing before reaching the film formation chamber, resulting in poor crystallinity and compositional deviation of the film. Therefore, it is difficult to stably transport organometallic compound raw materials to the film formation chamber, expensive raw materials become disposable after each film formation, and film composition control is difficult, and good dielectric properties. There is also a problem that a dielectric film having a thickness cannot be formed. Further, in this method, when the vaporization rate is suppressed and the synthesis (reaction) time is lengthened, the stability of the raw material deteriorates with time and the vaporization property gradually decreases. It was inevitable that the composition in the thickness direction became inhomogeneous and the leakage current increased.
[0007]
As a method for solving such a problem, a solution vaporization CVD method capable of stably supplying a raw material organometallic compound to a film formation chamber is widely used. This solution vaporization CVD method is an improvement of the MOCVD method, in which a solid CVD raw material is dissolved in various organic solvents and supplied as a liquid to a CVD apparatus.
[0008]
[Problems to be solved by the invention]
However, although the effect of improving the long-term storage stability of the solution raw material was obtained by purifying the organometallic compound as a raw material, a dielectric thin film was formed on the substrate using this highly purified raw material by the MOCVD method. In this case, variation in film quality between material lots, as shown in FIGS. 3 to 5, the
[0009]
An object of the present invention is to provide a solution raw material for forming a dielectric thin film capable of improving the film reproducibility of the formed dielectric thin film and stabilizing the surface morphology.
[0010]
[Means for Solving the Problems]
The invention according to claim 1, the organic metal compound precursor, tetrahydrofuran dielectric thin film
In the invention which concerns on Claim 1, this water suppresses the intramolecular and intermolecular interaction of an organometallic compound by including 10-200 ppm of water as an additive in the raw material liquid which melt | dissolved the organometallic compound raw material in the organic solvent. Therefore, the dielectric thin film formed using this solution raw material has good film formation reproducibility, and the surface morphology is stabilized. The amount of water added is 10 to 200 ppm. Preferably it is 90-150 ppm. When the addition amount is less than the lower limit value, intramolecular and intermolecular interactions of the organometallic compound cannot be suppressed, and effects such as improvement in film reproducibility and stabilization of surface morphology do not appear. When the addition amount exceeds the upper limit value, the formed thin film causes abnormal growth.
[0012]
The invention according to
The invention according to claim 3 is the invention according to
The invention according to claim 4 is the invention according to claim 3 , which is a method of supplying separate solution raw materials for each metal to the vaporizing chamber.
In the invention according to 4 or to
[0013]
The invention according to claim 5 is a dielectric thin film made of barium strontium titanate formed on a substrate by the method according to any one of
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
The dielectric thin film of a composite oxide which may be formed according to a solution raw material according to the present invention, a titanium barium strontium (BST).
[0015]
In the case of a BST thin film, Ti, Ba, and Sr organometallic compounds are used as raw materials.
[0016]
The organic metal compound raw material is vaporizable and is thermally decomposed by heating and easily converted into an oxide by introducing an oxidant (oxygen). Such an organometallic compound is generally a compound having a structure in which a metal atom is bonded to an organic group through an oxygen atom. Examples of this type of preferred compound include metal alkoxides, metal β-diketonato complexes, mixtures of metal alkoxides and β-diketonato complexes, and the like. Examples of β-diketonato complexes include metal complexes having β-diketones such as acetylacetone, hexafluoroacetylacetone, dpm, pentafluoropropanoylpivaloylmethane, etc. as ligands. Among these, a complex with dpm is preferable. As the metal alkoxide, those having 1 to 6 carbon atoms of the alkoxy group are preferable, and those having a branched alkoxy group (isopropoxide, tert-butoxide, etc.) are particularly preferable. Particularly preferred organometallic compounds are metal dipivaloylmethanato complexes, metal isopropoxides, metal tert-butoxide, mixtures of metal isopropoxide and dipivaloylmethanato complexes, metal tert-butoxide and dipivaloylmethanato It is a mixture of complexes. For alkaline earth metals, alkali metals, and Pb, β-diketonato complexes (for example, dipivaloylmethanato complexes) are preferred. For transition metals such as Ti, Zr, V, and Nb, β-diketonato complexes are generally used. And a metal alkoxide can be used, and a mixture of a metal alkoxide and a β-diketonato complex can also be used.
[0017]
As a raw material for forming a BST thin film, dipivaloylmethanato complexes of Ba and Sr, isopropoxide, tert-butoxide, dipivaloylmethanato complex, a mixture of isopropoxide and dipivaloylmethanato complex, and tert It is preferred to use a Ti compound selected from a mixture of butoxide and dipivaloylmethanato complex .
[0018]
Examples of the organic solvent include one or more selected from the group consisting of THF, methyltetrahydrofuran, n-octane, isooctane, hexane, cyclohexane, pyridine, lutidine, butyl acetate, and amyl acetate. Preferably it is THF.
[0019]
The solution raw material for forming a dielectric thin film of the present invention is characterized by containing 10 to 200 ppm of water as an additive in a raw material liquid obtained by mixing one or more organic metal compound raw materials and an organic solvent. .
[0020]
For example, a raw material liquid obtained by mixing [Ba (dpm) 2 ] as an organometallic compound and THF as an organic solvent and dissolving the organometallic compound in the organic solvent has a metal element Ba in [Ba (dpm) 2 ]. Since the α orbit is electronically empty, the metal Ba and the ligand dpm cause bond cleavage in the organometallic compound molecule (intramolecular cleavage), and the metal Ba is intercalated between the molecules. Polymerization occurs between the ligands dpm and the quantity is increased. Since the oligomers that have increased in quantity are thermally unstable, when vaporized in the vaporization chamber of the CVD apparatus, they are heated and separated into indeterminate small molecules and organic compounds. Molecules that are partially oligomers are supplied at the same time. Therefore, the dielectric thin film formed on the substrate does not have film formation reproducibility on the step-coated surface in sub-micron units, and surface roughness occurs, resulting in a morphological abnormality.
[0021]
By including 10 to 200 ppm of water as an additive in this raw material liquid, water has a coordination property to the metal Ba, thereby bringing about a trap effect on the empty α orbit of the metal element and forming an intermolecular polymer. Therefore, stable vaporization at the time of thin film formation is maintained, film reproducibility of the formed dielectric thin film is improved, and the morphology of the thin film surface is stabilized. Although the organometallic compound containing Ba has been described as an example, the same coordination stabilization effect can be obtained with an organometallic compound containing Sr (for example, [Sr (dpm) 2 ]).
[0022]
In the case of an organometallic compound containing Ti (for example, [Ti (Oi-Pr) 2 (dpm) 2 ]), polymerization into an oxonium complex is caused by water, and the transition or arrangement of the Ti compound into a hydroxyl complex is caused. As a result, the Ti complex after polymerization is more stable, has better steric hindrance and adhesion to the substrate, and the initial growth of TiO 2 is conformal and easy. Occur. Furthermore, the effect on the metal Ti is considered to have a synergistic effect with the effect of stabilizing the coordination of the metal Sr and the metal Ba.
[0023]
As a method for preparing the solution raw material of the present invention, two or more kinds of organometallic compounds containing each metal element constituting the dielectric thin film are dissolved together or separately in an organic solvent, and water is further added as an additive. A solution raw material used for forming a dielectric thin film by MOCVD is prepared by containing 10 to 200 ppm. Using this solution raw material, a dielectric thin film is formed on a substrate or other substrate by MOCVD. In this embodiment, the MOCVD method uses a solution vaporization CVD method in which each solution is supplied to a heated vaporization chamber, where each solution raw material is instantaneously vaporized and sent to a film formation chamber.
[0024]
As shown in FIG. 2, the MOCVD apparatus includes a
In this apparatus, a carrier gas composed of an inert gas such as N 2 , He, Ar is introduced into the
[0025]
In the solution raw material of the present invention, the vaporization property of each raw material compound in a solution state is stable, and the metal atomic ratio of the formed thin film is almost the same as the metal atomic ratio in the solution. A complex oxide dielectric thin film can be formed, and the quality of the film is stabilized.
[0026]
The dielectric thin film formed by the MOCVD method using the solution raw material of the present invention is useful as a capacitor for DRAM. Although the MOCVD method is generally excellent in step coverage, the use of the solution raw material of the present invention improves the film reproducibility and stabilizes the surface morphology as compared with a thin film formed using a conventional solution raw material.
In addition, since the solution raw material of the present invention can stably supply the vapor of each raw material compound to the film formation chamber as described above, it has excellent film composition controllability, and has a desired composition and dielectric characteristics. The body thin film can be stably formed on the substrate. The dielectric thin film formed using the solution raw material of the present invention can also be used as a dielectric filter for a piezoelectric resonator, an infrared sensor, or the like.
[0027]
【Example】
Next, examples of the present invention will be described together with comparative examples.
<Example 1>
First, bis (dipivaloylmethanato) barium complex [Ba (dpm) 2 ] as the organic barium compound, bis (dipivaloylmethanato) strontium complex [Sr (dpm) 2 ] as the organic strontium compound, and organic titanium compound Bisisopropoxybisdibivaloylmethanate titanium complex [Ti (Oi-Pr) 2 (dpm) 2 ] was prepared. Moreover, THF was prepared as an organic solvent and water was used as an additive.
Next, each organic metal compound raw material and THF are mixed to prepare a raw material liquid in which each organic metal compound raw material is dissolved in THF. Further, 100 ppm of water is added to this raw material liquid to thereby prepare a BST dielectric thin film solution raw material. Was prepared.
[0028]
<Example 2>
A solution raw material for a BST dielectric thin film was prepared in the same manner as in Example 1 except that the amount of water added was 200 ppm.
[0029]
<Comparative Example 1>
A solution raw material for a BST dielectric thin film was prepared in the same manner as in Example 1 except that the additive was not added.
<Comparative example 2>
A solution raw material for a BST dielectric thin film was prepared in the same manner as in Example 1 except that the amount of water added was 5 ppm.
<Comparative Example 3>
A solution raw material for a BST dielectric thin film was prepared in the same manner as in Example 1 except that the amount of water added was 210 ppm.
[0030]
<Comparison evaluation>
The BST dielectric thin film solution raw materials prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were each divided into two and introduced into an MOCVD apparatus as shown in FIG. Each type was formed. Deposition reproducibility of two types of BST dielectric thin films formed of the same material on the substrate surface using an atomic force microscope (AFM) or a scanning tunneling microscope (hereinafter referred to as STM). The film quality of the formed thin film was measured. Moreover, the surface of the formed dielectric thin film was observed, and the surface morphology was investigated.
Table 1 shows the long-term storage stability of the solution raw materials for the BST dielectric thin film of Examples 1-2 and Comparative Examples 1-3, the film formation reproducibility of the formed dielectric thin film, and the surface morphology, respectively.
[0031]
[Table 1]
As is clear from Table 1, the film formation reproducibility is poor and the surface morphology is not stable in Comparative Example 1 using a solution raw material containing no additive. Further, in Comparative Examples 2 and 3 in which the amount of water as an additive is outside the scope of the present invention, as shown in FIGS. 3 to 5, the film quality varies, and a film is formed only at the bottom of the trench. The thin film other than the trench grew abnormally, and the surface morphology was not stable. In contrast, in Examples 1 and 2, as shown in FIG. 1, the dielectric thin film formed using the solution raw material of the present invention has good film reproducibility and stable surface morphology. I understand.
[0033]
【The invention's effect】
Above As mentioned, the dielectric thin film-forming raw material solution of the present invention, the organic metal compound materials, dielectrics water containing 10~200ppm as an additive to the raw material solution formed by combining an organic solvent consisting of tetrahydrofuran A solution raw material for forming a thin film, wherein the organometallic compound is composed of a bis (dipivaloylmethanato) barium complex, a bis (dipivaloylmethanato) strontium complex and a bisisopropoxybisdibivaloylmethanato titanium complex Since this water suppresses the intramolecular and intermolecular interaction of the organometallic compound, the film reproducibility of the dielectric thin film formed using this solution raw material is improved and the surface morphology is stabilized.
[Brief description of the drawings]
FIG. 1 is a view showing a surface morphology around a trench of a dielectric thin film formed on a substrate using the dielectric material for forming a dielectric thin film of the present invention.
FIG. 2 is a schematic view of an MOCVD apparatus.
FIG. 3 is a view showing a surface morphology around a trench of a dielectric thin film formed on a substrate using a conventional solution raw material for forming a dielectric thin film.
FIG. 4 is a view showing a surface morphology around a trench of a dielectric thin film formed on a substrate using another conventional raw material for forming a dielectric thin film.
FIG. 5 is a view showing a surface morphology around a trench of a dielectric thin film formed on a substrate using still another conventional dielectric thin film forming solution raw material.
[Explanation of symbols]
13
Claims (5)
前記有機金属化合物がビス（ジピバロイルメタナト）バリウム錯体、ビス（ジピバロイルメタナト）ストロンチウム錯体及びビスイソプロポキシビスジビバロイルメタナートチタン錯体からなることを特徴とする誘電体薄膜形成用溶液原料。And organic metal compound precursor, a dielectric thin film-forming raw material solution containing 10~200ppm water as an additive to the raw material solution formed by combining an organic solvent consisting of tetrahydrofuran,
For forming a dielectric thin film characterized in that the organometallic compound is composed of a bis (dipivaloylmethanato) barium complex, a bis (dipivaloylmethanato) strontium complex, and a bisisopropoxybisdibivaloylmethanato titanium complex Solution raw material.
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