JP3672941B2 - Wiring structure for semiconductor integrated circuit - Google Patents

Description

【００３２】
次に、図１から図７まで参照して、本発明の配線構造体とその製造方法の一例を説明する。図１に示されるように、シリコン基板１０の表面に５０００ÅのＢＰＳＧ（Ｂｏｒｏｐｈｏｓｐｈｏｓｉｌｉｃａｔｅ Ｇｌａｓｓ）の絶縁膜１２を形成する。この絶縁膜１２の全表面に、図２に示されるように、タングステン膜１４をＲＦマグネトロンスパッタリングによってアルゴン雰囲気下全圧２ｍＴｏｒｒ、成膜速度１０Å／ｓで６００Å形成する。次に、図３に示されるように、このタングステン膜１４の表面に、窒素ガス圧１ｍＴｏｒｒ、窒素流量２０ｓｃｃｍで、マイクロ波出力６００ＷのＥＣＲプラズマを６０秒間照射することにより、非晶質Ｗ−Ｎ膜１６を、約２０Å形成する。次に、図４に示されるように、この非晶質Ｗ−Ｎ膜１６の表面に、銅膜１８をＲＦマグネトロンスパッタリングによってアルゴン雰囲気下全圧２ｍＴｏｒｒ、成膜速度６０Å／ｓで形成する。その後、図５に示されるように、銅膜１８、Ｗ−Ｎ膜１６、及びタングステン膜１４をパターニングして銅配線２０を形成する。さらにその後、図６に示されるように、ＣＶＤ法によって、タングステンを銅配線２０、Ｗ−Ｎ膜１６、及びタングステン膜１４の外面のみに選択的に４００Å成長させてタングステン被覆膜２２を形成する。このタングステン被覆膜２２は、試料温度を２００℃〜４００℃とし、六フッ化タングステンガスと水素ガスの混合ガスを成膜室に供給し、ガス圧を１Ｔｏｒｒ以下とすることにより形成する。この成膜方法によると、界面反応が律速となり、銅配線２０、Ｗ−Ｎ膜１６、およびタングステン膜１４の外面にのみタングステンを選択成長させることができる。最後に、図７に示すように、ＣＶＤタングステン膜の表面を、再び窒素ガス圧１ｍＴｏｒｒ、窒素流量２０ｓｃｃｍで、マイクロ波出力６００ＷのＥＣＲプラズマを６０秒間照射して、非晶質Ｗ−Ｎ膜２４を約２０Å形成する。
【００３３】
ここで、この配線構造体を多層化するためには、非晶質Ｗ−Ｎ膜２４の上に、通常のＳｉＯ₂ 等の絶縁層を設け、この絶縁膜の上に、上記した配線構造体を同様の方法で製造すればよい。
プラズマ窒化膜の膜厚は、プラズマ電力、加速電圧、基板温度等を変化させることによって制御できる。ＥＣＲプラズマを用いた場合、加速なし、プラズマ電力６００Ｗ、基板温度室温の条件下で約２０ÅのＷ−Ｎ膜を４０秒以上の窒化時間で形成できる。この膜厚は、窒化時間を５分まで増加させてもほとんど増加しなかった。またこの膜に含まれるＷ原子とＮ原子との組成比は１に近い（１±０．２）ことがＡＥＳ（Ａｕｇｅｒ Ｅｌｅｃｔｒｏｎ Ｓｐｅｃｔｒｏｓｃｏｐｙ）によって確認された。
【００３４】
基板温度を１００℃に高めることによって５０Åまで、さらに２００℃に高めることによって１００ÅにまでＷ−Ｎ膜厚を増加させることができた。ただし５０Å以上ではバリア性に顕著な向上は見られず、一方、Ｗ膜厚が減少することによって配線抵抗は僅かながら増大した。さらに、基板温度２００℃において、基板に２００Ｖの加速電圧を加えることによって１５０ÅまでＷ−Ｎ膜厚を増加させることができた。ただし膜厚が１００Åを越えると、粗な窒化金属膜が形成され、かえってバリア性は劣化した。
【００３５】
一方プラズマ電力を低下させたり、照射時間を４０秒以下に短縮させたりすることにより、より薄いＷ−Ｎ膜を得ることもできる。例えばプラズマ電力２００Ｗ、窒化時間１０秒において８ÅにまでＷ−Ｎ膜厚を減少させることができた。ただし膜厚が１０Å未満になると、顕著にバリア性が低下した。
従って、Ｗ−Ｎ膜厚は１０Å〜１００Åの範囲にすることが好ましく、さらに１０Å〜５０Åの範囲にすることが好ましい。
【００３６】
窒化に使用するプラズマの発生方法は、金属膜表面を実用的な時間内で窒化させるため、高い密度のプラズマを発生できる方法が望ましい。通常の１３．５６ＭＨｚの高周波プラズマでは、実用的な窒化時間内で十分なＷ−Ｎ膜厚を得る条件は見出せなかった。通常の高周波プラズマではプラズマ密度が１×１０¹⁰ｃｍ^-3程度と低いためと解釈できる。これに対してＥＣＲでは５×１０¹⁰ｃｍ^-3以上の高いプラズマ密度を得ることができるため、４０秒という短時間の窒化によって十分な膜厚のＷ−Ｎ膜を得ることができたものと解釈できる。
【００３７】
ＥＣＲと同様に高密度のプラズマを得ることができるプラズマ発生方法としては、ヘリコン（Ｈｅｌｉｃｏｎ）プラズマ、ＩＣＰ（Ｉｎｄｕｃｔｉｖｅ Ｃｏｕｐｌｅｄ Ｐｌａｓｍａ）、ＴＣＰ（Ｔｒａｎｓｆｏｒｍｅｒ Ｃｏｕｐｌｅｄ Ｐｌａｓｍａ）等が好適に使用できる。
また、Ｗ−Ｔａ合金，Ｍｏ，Ｎｂ，ＴｉがＴａに添加されたＴａ系合金、Ｍｏ，Ｎｂ，Ｐｄ，ＰｂがＷに添加されたＷ系合金の表面を窒化した積層構造からなるバリア層を使用することにより、さらに高いバリア性が得られる。
【００３８】
［第２実施例］
バリア材料としてＮｂとプラズマ窒化Ｎｂを用いた配線構造体の製造方法を、図８から図１０までを参照して説明する。
図８に示されるように、Ｓｉ基板３０の表面に５０００ÅのＢＰＳＧ（Ｂｏｒｏｐｈｏｓｐｈｏｓｉｌｉｃａｔｅ ｇｌａｓｓ）の絶縁膜３２を形成し、この絶縁膜３２の表面に、Ｎｂ結晶質膜３４を形成する。このＮｂ結晶質膜３４は、全圧２ｍＴｏｒｒのＡｒ雰囲気中で、ＲＦマグネトロンスパッタリングにより成膜速度１０Å／ｓで１０００Å成長させた。その後、このＮｂ結晶質膜３４の表面に、Ｎ₂ ガス圧１ｍＴｏｒｒ（流量２０ｓｃｃｍ）、出力４００ＷのＥＣＲプラズマを６０秒間照射することによりＮｂ結晶質膜３４の表面を窒化し、プラズマ窒化Ｎｂ薄膜（Ｎｂ−Ｎ）３４ａを形成した。このプラズマ窒化Ｎｂ薄膜３４ａの表面に、Ｃｕ膜３６をＲＦマグネトロンスパッタリングにより２ｍＴｏｒｒのＡｒ雰囲気中で形成し、図９に示されるように、これらをパターニングしてＣｕ配線３６ａを形成した。図１０は、Ｃｕ配線３６ａとこのＣｕ配線３６ａの下地膜を示す拡大図であり、Ｎｂ結晶質膜３４の上部にはプラズマ照射により非晶質の窒化Ｎｂ薄膜３４ａが形成されている。なお。Ｃｕ膜３６の代わりにＡｌ−Ｃｕ合金膜を形成した場合にも、Ｎｂ−Ｎ／Ｎｂ層積膜はＡｌ−Ｃｕ合金膜中のＣｕの拡散を防止するために有効である。
［第３実施例］
ここでは、配線構造体の実施例を、比較例と共に説明する。
【００３９】
表２は、上記の方法で形成したＮｂ結晶質膜とプラズマ窒化Ｎｂ薄膜（Ｎｂ−Ｎ）を用いた実施例、スパッタリングによって１０００ÅのＴｉ−Ｎを下地として形成した比較例、及び下地を絶縁膜のままとした比較例それぞれ配線抵抗の値である。試料は、Ａｌ−Ｃｕ合金配線と下地膜を合わせた合計の膜厚が１００００Åとなるように積膜し、プラズマ窒化Ｎｂ薄膜の厚さは２５Å〜５０Åの範囲である。
【００４０】
表３は、上記の方法で作製したプラズマ窒化金属薄膜を用いた実施例、及び各種の下地材料を用いた比較例の、Ｃｕに対するバリア性をＳＩＭＳ（Ｓｅｃｏｎｄａｒｙ−Ｉｏｎ Ｍａｓｓ Ｓｐｅｃｔｒｏｓｃｏｐｙ 二次イオン質量分析）によって評価した結果である。試料は下地の上にＣｕを１０００Å積膜し、Ｈ₂ 雰囲気中で６００℃×１ｈの熱処理（昇温速度：１００℃／ｈ）を行ったもので、これらをＳＩＭＳを用いてＣｕのデプスプロファイルを得ることにより、Ｓｉウエハ中のＣｕの濃度を比較した。
【００４１】
【表２】

【００４２】
【表３】

【００４３】
表２，３に示されるように、これまで提案されている金属膜、窒化物膜に比べ本実施例のように下地の表面をプラズマ窒化しプラズマ窒化金属薄膜を形成すると、配線抵抗の上昇を抑制できると共にＣｕの拡散を著しく減少させることができる。
［第４実施例］
次に、配線構造体の他の実施例を、比較例とともに説明する。
【００４４】
表４は、同じ厚さを持つ各種バリア層のＣｕに対するバリア性の相違を比較するために、Ｃｕ／Ｍ／Ｓｉ（Ｍは各種バリア層を表わす）積層膜を拡散熱処理した後、Ｓｉ表面のＣｕ濃度をＳＩＭＳ（Ｓｅｃｏｎｄａｒｙ−Ｉｏｎ Ｍａｓｓ
Ｓｐｅｃｔｒｏｓｃｏｐｙ）によって測定した結果である。
【００４５】
【表４】

【００４６】
比較例の試料は、先ず、Ｓｉ基板上に単層のバリア膜をＲＦマグネトロンスパッタリングにより６００Å堆積させた。一方、実施例の試料は、先ず、Ｓｉ基板上に金属膜をＲＦマグネトロンスパッタリングで形成し、この金属膜の表面にプラズマ窒化金属薄膜をＥＣＲプラズマ窒化法により形成して１層目とし、この１層目の上に上記方法で金属膜、プラズマ窒化金属薄膜を順次形成して厚さ６００Åの多層のバリア層を形成した。さらに、これら比較例と実施例の試料の表面に、ＣｕをＲＦマグネトロンスパッタリングにより５０００Å積層して多層膜を形成し、この多層膜が形成されたこれらの試料に、Ｈ₂ ガス雰囲気中で６４０℃×１ｈの熱処理を施し、その後、Ｓｉ表面のＣｕ濃度をＳＩＭＳを用いて測定し、比較した。表３から明らかなように、従来のＣｒ、Ｍｏ、ＴｉＮ等のバリア膜に比べて、実施例のバリア層ではＳｉ表面のＣｕ濃度が著しく減少しており、本発明の有効性が明らかに分かる。
【００４７】
次に、図１１から図１３までを参照して、上記表４のうちのＷ膜とプラズマ窒化Ｗ薄膜（Ｗ−Ｎ／Ｗ）からなる層を６層に積層したバリア層が形成された配線構造体の形成方法を説明する。図１１に示されるようにに、Ｓｉ基板４０の表面に５０００ÅのＢＰＳＧ（Ｂｏｒｏｐｈｏｓｐｈｏｓｉｌｉｃａｔｅ ｇｌａｓｓ）の絶縁膜４２を形成し、この絶縁膜４２の全表面にＷ膜を、全圧２ｍＴｏｒｒのＡｒガス雰囲気中でＲＦマグネトロンスパッタリングにより成膜速度１０Å／ｓで１００Å成長させる。このＷ膜の表面に、Ｎ₂ ガス圧力１ｍＴｏｒｒ，プラズマ出力４００ＷのＥＣＲプラズマを６０ｓ照射することによりＷ膜の表面を窒化してプラズマ窒化膜を形成し、これによりＷ膜とプラズマ窒化Ｗ薄膜からなる層を形成する。この層の上に、上記方法の繰り返しによって膜厚６００Åの多層のバリア層４４を形成する。このバリア層４４の表面に、Ｃｕ膜４６を全圧２ｍＴｏｒｒのＡｒガス雰囲気中でＲＦマグネトロンスパッタリングにより成膜速度６０Å／ｓで５０００Å成長させる。その後、図１２に示されるように、バリア層４４とＣｕ膜４６をパターニングして下地膜４４ａと配線４６ａを形成する。さらにその後、図１３に示されるように、ＣＶＤ法によりＷを下地膜４４ａと配線４６ａの外面のみに４００Å成長させてＷ被覆膜４８を形成する。このＷ被覆膜４８は、試料温度を２００〜４００℃としＷＦ₆ とＨ₂ の混合ガスを成膜室へ供給し、この混合ガスの圧力を１Ｔｏｒｒ以下にして形成する。この成膜方法によると、界面反応が律速となり、下地膜４４ａと配線４６ａの外面のみにＷを選択成長させることができる。ここで、この配線構造体を多層化するためには、Ｗ被覆膜４８上にＳｉＯ₂ 膜など絶縁膜を形成し、この絶縁膜の上に上記した配線構造体を同様の方法で作製すればよい。
［第５実施例］
先ず、表５〜表７に、各種材料のＣｕに対するバリア性を比較した実験結果を示す。この実験は、各種材料のバリア性を比較するために、Ｃｕ／Ｍ／Ｓｉ積層膜（Ｍは各種バリア膜材料を表す。）積層膜を形成し拡散熱処理した後、Ｓｉ表面のＣｕ濃度をＳＩＭＳ（Ｓｅｃｏｎｄａｒｙ−Ｉｏｎ Ｍａｓｓ Ｓｐｅｃｔｒｏｓｃｏｐｙ 二次イオン質量分析）により測定したものである。
【００４８】
これらの多層膜は、Ｎ₂ とＡｒの混合ガス又はＡｒガスを用いて、ＲＦマグネトロンスパッタリングによりＳｉ基板上にバリア材料合金膜を６００Å堆積させ、さらにこのバリア材料合金膜上に、ＡｒガスのＲＦマグネトロンスパッタリングによりＣｕを５０００Å堆積させて形成した。その後、これらの多層膜に、Ｈ₂ ガス雰囲気中で６５０℃×１．５ｈの熱処理を施し、Ｓｉ基板表面のＣｕ濃度をＳＩＭＳ用いて測定し比較した。
【００４９】
【表５】

【００５０】
【表６】

【００５１】
【表７】

【００５２】
表５〜表７から明らかなように、各種合金の窒化物、硼化物、及び炭化物は従来のバリア材料に比べてバリア効果が優れていることがはっきりと分かる。
次に、図１４から図１６までを参照して、本発明の配線構造体とその製造方法の一例を説明する。
図１４に示されるように、Ｓｉ基板５０の表面に５０００ÅのＢＰＳＧ（Ｂｏｒｏｐｈｏｓｐｈｏｓｉｌｉｃａｔｅ ｇｌａｓｓ）の絶縁膜５２を形成し、この絶縁膜５２の全表面にＴａ₁₅Ｗ₈₀Ｍｏ₅ −Ｎ膜５４（Ｔａ₁₅Ｗ₈₀Ｍｏ₅ −Ｎは、１５ａｔ％のＴａ、８０ａｔ％のＷ、５ａｔ％のＭｏからなる合金の窒化物を表す。）を、全圧２ｍＴｏｒｒのＡｒ５０％、Ｎ₂ ５０％ガス雰囲気中でＲＦマグネトロンスパッタリングにより成膜速度１０Å／ｓで６００Å成長させる。このＴａ₁₅Ｗ₈₀Ｍｏ₅ −Ｎ膜５４の表面にＣｕ膜５６を、全圧２ｍＴｏｒｒのＡｒガス雰囲気中でＲＦマグネトロンスパッタリングにより成膜速度６０Å／ｓで５０００Å成長させる。その後、図１５に示されるように、Ｔａ₁₅Ｗ₈₀Ｍｏ₅ −Ｎ膜５４とＣｕ膜５６をパターニングして下地膜５４ａとＣｕ配線５６ａを形成する。さらにその後、図１６に示されるように、ＣＶＤ法によりＷを下地膜５４ａとＣｕ配線５６ａの外面のみに選択的に４００Å成長させ、Ｗ被覆膜５８を形成する。このＷ被覆膜５８は、試料温度を２００〜４００℃としＷＦ₆ とＨ₂ の混合ガスを成膜室へ供給し、この混合ガスのガス圧を１Ｔｏｒｒ以下にすることにより形成する。この成膜方法によると、界面反応が律速になり、下地膜５４ａとＣｕ配線５６ａの外面のみにＷを選択成長させることができる。ここで、この配線構造体を多層化するためには、Ｗ被覆層５８上にＳｉＯ₂ 等の絶縁膜を設け、この絶縁膜上に上記した配線構造体を同様の方法で作製すればよい。
【００５３】
【発明の効果】
以上説明したように本発明の第１の配線構造体は、金属膜と金属化合物膜とを重ねた少なくとも１つの積層からなるバリア層を配線の下地又は被覆にしたため、配線抵抗を上昇させることなくＣｕの拡散を防止させることができ、信頼性に優れた半導体の配線構造を実現することができた。従って本発明の工業的意義は非常に大きいものとなる。本発明を、Ｃｕ配線に適用すると、Ｃｕ配線の抵抗を上昇させることなくＣｕの拡散を防止することができ、信頼性に優れた半導体の配線構造体を実現することができる。
【００５４】
また、本発明の第２の配線構造体は、金属膜とこの金属膜を構成する金属の窒化金属薄膜からなる層が少なくとも１層形成されたバリア層が形成されているため、バリア層表面に形成されるＣｕ膜の平坦性が改善されパターニング加工工程におけるパターン形状の不良率が著しく改善される。
また、本発明の第３から第６までの半導体集積回路の配線構造体では、バリア性の良好なＴａ−Ｗ合金、Ｔａ−Ｗ系合金、Ｔａ系合金、Ｗ系合金の窒化物、硼化物、炭化物をＣｕ配線の下地及び／又は被覆にしているため、Ｃｕの拡散を十分に抑制した配線構造体を実現することができる。したがって、本発明により、比抵抗がＡｌより小さく耐エレクトロマイグレーションに優れた、工業的意義が非常に大きいＣｕ配線が実現できる。
【図面の簡単な説明】
【図１】本発明の第１実施例の配線構造体の製造方法を示す断面図である。
【図２】本発明の第１実施例の配線構造体の製造方法を示す断面図である。
【図３】本発明の第１実施例の配線構造体の製造方法を示す断面図である。
【図４】本発明の第１実施例の配線構造体の製造方法を示す断面図である。
【図５】本発明の第１実施例の配線構造体の製造方法を示す断面図である。
【図６】本発明の第１実施例の配線構造体の製造方法を示す断面図である。
【図７】本発明の第１実施例の配線構造体の製造方法を示す断面図である。
【図８】本発明の第２実施例の配線構造体の製造方法を示す断面図である。
【図９】本発明の第２実施例の配線構造体の製造方法を示す断面図である。
【図１０】本発明の第２実施例の配線構造体の製造方法を示す断面図である。
【図１１】本発明の第４実施例の配線構造体の製造方法を示す断面図である。
【図１２】本発明の第４実施例の配線構造体の製造方法を示す断面図である。
【図１３】本発明の第４実施例の配線構造体の製造方法を示す断面図である。
【図１４】本発明の第５実施例の配線構造体の製造方法を示す断面図である。
【図１５】本発明の第５実施例の配線構造体の製造方法を示す断面図である。
【図１６】本発明の第５実施例の配線構造体の製造方法を示す断面図である。
【符号の説明】
１０，３０，４０，５０ Ｓｉ基板
１２，３２，４２ 絶縁膜
１４ タングステン膜
１６，２４ 非晶質ＷＮ_X 膜
１８，３６，４６ Ｃｕ膜
２０，３６ａ，４６ａ Ｃｕ配線
２２ タングステン被覆膜
３４ Ｎｂ結晶質膜
３４ａ プラズマ窒化Ｎｂ薄膜
４４ バリア層
４４ａ 下地膜[0001]
[Industrial application fields]
The present invention relates to a semiconductor integrated circuit (LSI) wiring structure and a method for manufacturing the same.
[0002]
[Prior art]
Currently, Al or an Al alloy obtained by adding Si, Cu, or the like to Al is used as a wiring material of a semiconductor integrated circuit. Since such a wiring uses Al as a main material, the allowable current density of the wiring is (2-3) × 10.^Five A / cm² Restricted to: When a current exceeding the allowable current density is passed through the wiring, the wiring is disconnected by electromigration. Particularly in recent years, the problem of electromigration becomes important because metal wiring tends to shrink as the degree of integration increases.
[0003]
Moreover, since the specific resistance of the Al alloy is high, the wiring resistance increases as the wiring pattern becomes finer. For this reason, the wiring delay due to the increase of the time constant is increased, and the merit that the operation speed of the transistor is improved by miniaturization is offset. Furthermore, there is a problem that reliability is lowered due to heat generation caused by flowing current at a high current density.
[0004]
For the above reasons, in order to improve the migration resistance of the wiring and lower the resistance, a Cu wiring made of substantially Cu having a high electromigration resistance and a low specific resistance is used instead of the Al wiring or the Al alloy wiring. Has been proposed.
[0005]
[Problems to be solved by the invention]
However, Cu is Si (substrate) or SiO compared to Al.₂ Easy to diffuse into (insulating film). Therefore, if Cu is used as a wiring material as it is, it diffuses to the active region to form an acceptor level, and the carrier density is greatly reduced, which causes a problem of hindering normal operation of the transistor. In order to solve this problem, there has been proposed a technique for preventing diffusion of Cu by using a barrier film formed of various materials as a base or coating for Cu wiring (for example, Japanese Patent Laid-Open No. 53-116089). JP, 63-73645, JP, 63-156341, JP, 1-204449, and Cu) Si or SiO via a barrier film.₂ It cannot be sufficiently prevented from diffusing to the surface, and a sufficient effect is not achieved. In addition, a technique for forming a barrier film with nitrides such as Ti—N and W—N and carbides such as Ti—C and WC (US Pat. No. 4,985,750), and the surface of Ti—N are oxidized. Although a technique for forming a barrier film (US Pat. No. 5,236,869) has been proposed, since nitride has a high electric resistance, the wiring resistance is higher than a barrier film made of W or the like. Occurs.
[0006]
Further, although it has been proposed to use nitrides and borides such as Zr, Ti, and Ta as the base of the Cu wiring (Japanese Patent Laid-Open No. 1-202841), although the adhesion to the insulating film is improved, Cu The anti-diffusion effect is not sufficient.
Au and Ag are also promising because they have lower resistance than Al and high electromigration resistance, like Cu. However, as well as Cu, Si or SiO₂ There is a need for a barrier film that easily diffuses in, has a high barrier effect, and does not increase wiring resistance.
[0007]
Further, it is a common practice to use an alloy to which Cu is added in order to improve the electromigration resistance of the Al wiring. In this case, a barrier film for preventing the diffusion of Cu is necessary.
In view of the above circumstances, the present invention provides a wiring structure of a semiconductor integrated circuit that improves electromigration resistance of wiring and suppresses diffusion of atoms of the wiring material to an insulating film or a substrate, and a method for manufacturing the same. For the purpose.
[0008]
[Means for Solving the Problems]
  To achieve the above object, a wiring structure of a first semiconductor integrated circuit according to the present invention is a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al—Cu alloy. In a semiconductor integrated circuit wiring structure comprising:Ta film and formed on the surface of the Ta filmA nitrided Ta film having a thickness in the range of 10 to 100 mm;Composed ofA wiring structure of a semiconductor integrated circuit, comprising at least one barrier layer made of a laminate as a base and / or covering for the wiring. in this case,The wiring coating is preferably a barrier layer made of a laminate composed of a Ta film in contact with the wiring on the side surface of the wiring and a Ta nitride film formed outside the Ta film.
[0009]
  Here, the Ta nitride film is preferably amorphous.
  Preferably, the upper limit of the thickness of the metal compound film is 50 mm, or the wiring is made of a metal selected from Cu, Cu alloy, or Cu. In addition, it is preferable to provide the barrier layer as a base for the wiring layer.
  In addition, the present invention provides:In a wiring structure of a semiconductor integrated circuit having a wiring made of Cu, at least one composed of a Ta film and a Ta nitride film formed on the surface of the Ta film and having a thickness in the range of 10 to 100 mm. A wiring structure of a semiconductor integrated circuit, comprising a barrier layer made of two layers as a base of the wiringIt is. Also in this case, the upper limit of the thickness of the Ta nitride film is preferably 50 mm.
[0010]
  In order to achieve the above object, a wiring structure of a second semiconductor integrated circuit according to the present invention comprises:In a wiring structure of a semiconductor integrated circuit provided with a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, and Ag alloy, the wiring structure is selected from Ta film, W film, and Ta-W alloy film. A barrier layer made of at least one laminate composed of a metal film and a metal nitride film of metal constituting the metal film and having a thickness in the range of 10 to 100 mm formed on the surface of the metal film Is provided as a base and / or coating for the wiring.Is.
  Again,The wiring covering comprises a metal film selected from a Ta film, a W film, and a Ta—W alloy film in contact with the wiring on the side surface of the wiring, and the metal film formed outside the metal film. It is preferable that the barrier layer is formed of a laminate composed of a metal nitride film of the metal. Also,The upper limit of the thickness of the metal nitride film is preferably 50 mm, or the wiring is preferably made of a metal selected from Cu, Cu alloy, or Cu. In addition, it is preferable that the barrier layer is provided particularly as a base of the wiring, or the metal film is a Ta film and the metal nitride film is a Ta nitride film.
[0011]
Here, as the metal film,
(1) Ta film,
(2) W film,
(3) Ta-W alloy film,
(4) Ta alloy film to which one or more metals selected from Mo, Nb, and Ti are added,
(5) W alloy film to which one or more metals selected from Mo, Nb, Pd, and Pb are added,
(6) Ta-W alloy film added with Mo and / or Nb,
It is preferable to use either of them.
[0012]
In order to achieve the above object, a wiring structure of a third semiconductor integrated circuit according to the present invention comprises a barrier layer selected from nitrides, borides, and carbides of Ta—W alloy with Cu, Cu alloy, Au , Au alloy, Ag, Ag alloy, and Al—Cu alloy are used as the base and / or coating of the wiring made of a metal. The wiring structure of the fourth semiconductor integrated circuit of the present invention is selected from nitrides, borides, and carbides of Ta—W alloys obtained by adding Mo and / or Nb to Ta—W alloys. The barrier layer is a base and / or coating of a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al—Cu alloy.
[0013]
Furthermore, the wiring structure of the fifth semiconductor integrated circuit of the present invention is a Ta-based alloy nitride, boride formed by adding one or more metals selected from Mo, Nb, and Ti to Ta, and A barrier layer selected from carbides is used as a base and / or coating of a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al-Cu alloy. Is.
[0014]
Furthermore, the wiring structure of the sixth semiconductor integrated circuit according to the present invention includes a W-based alloy nitride, boron, and the like, in which one or more metals selected from Mo, Nb, Pd, and Pb are added to W. The barrier layer selected from the compounds and carbides is used as a base and / or coating for a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al-Cu alloy. It is a feature.
[0015]
  Here, “nitride, boride, carbide” is not only a compound, but “N, B, C” is present as an interstitial atom or a substitution atom in a part of the alloy. Including things.
[0016]
  MaIn addition, the material of the metal film that can be used in manufacturing the wiring structure is not particularly limited, but as an effective material, the metal film can be formed relatively easily and can form a stable and dense nitride. Ti, Nb, Ta, W, etc. are raised. It is preferable to form this metal film as a crystal film by sputtering, vacuum vapor deposition or the like, and irradiate this surface with ECR plasma to form a plasma metal nitride thin film only on the surface.
[0017]
[Action]
In the wiring structure of the first semiconductor integrated circuit of the present invention, a metal film such as W, Mo, Ta or the like having a relatively low specific resistance and WN, Nb-N, Mo-N having a relatively high diffusion suppressing effect. , Ti—N and other metal compound films are used as the barrier layer, so that sufficient barrier performance can be obtained without impairing the wiring resistance.
[0018]
Even higher barrier performance can be obtained by using an amorphous film as the metal compound film having a relatively high diffusion suppressing effect in the multilayer barrier layer. When a polycrystalline material is used as a barrier material, Cu, Au, and Ag diffuse through crystal grain boundaries having a high diffusion rate. Therefore, even if a metal such as W, Ti—N, Zr—N or a metal compound film having a small diffusion coefficient of Cu, Au, Ag is used as the barrier layer, the diffusion cannot always be effectively prevented. Therefore, by using an amorphous film having no grain boundary as a barrier layer, fast grain boundary diffusion can be effectively prevented. As another method for preventing grain boundary diffusion, it is possible to use a single crystal film as a barrier layer, but it is practically extremely difficult to form a defect-free single crystal film on the entire surface of the substrate.
[0019]
When an amorphous material is used as one film of a barrier layer having a laminated structure, the diffusion rate of Cu, Au, and Ag in the barrier layer becomes negligible for grain boundary diffusion. Smaller is smaller. Therefore, barrier performance can be further improved by using a high melting point transition metal nitride having a small self-diffusion coefficient as the amorphous material.
[0020]
When an amorphous transition metal nitride is used as one film of a barrier layer having a laminated structure, the formation method is not limited, but in general, the other good conductivity barrier and the amorphous transition metal nitride are bonded to each other. It is formed by sequentially vapor-depositing. As an example, after forming a metal film by chemical vapor deposition or sputtering as one of the two types of laminated barriers, the metal film is continuously or transferred to another device, and then a high barrier property. The transition metal nitride film is formed by sputtering or reactive sputtering under conditions for making it amorphous. This method has a limit in the controllable range of the thickness of the transition metal nitride film. Therefore, a metal film is formed in advance as one of the good conductivity barriers of the laminated barrier, and then the surface is nitrided by irradiating nitrogen plasma, and the surface is made amorphous by the energy of the plasma. Can do. According to this method, by changing the plasma irradiation time, energy, and plasma source, a very small part of the surface has a very barrier property while sufficiently securing the thickness of the low-resistance barrier film previously formed. It is possible to easily form a structure having a high amorphous nitride film.
[0021]
Here, in the above-described method of plasma nitriding the surface, it is particularly preferable to use W or an alloy thereof as a specific material. Since the specific resistance of W is relatively low, an increase in specific resistance accompanying the miniaturization of wiring can be suppressed to a minimum. Further, W is easily nitrided by nitrogen plasma irradiation to form amorphous W-N. Since the barrier performance of amorphous W—N is very high compared to general metals, nitrides, etc., diffusion of Cu, Au, Ag can be prevented even with a very thin film of about 20 mm.
[0022]
As a process for forming a W—N / W multilayer film, first, W is formed on the insulating film by sputtering or CVD. Nitrogen plasma is irradiated on the W film. As a result, the W surface is nitrided and becomes amorphous. As a method for generating nitrogen plasma, it is preferable to use ECR that can generate high-density plasma. Next, for example, Cu is formed into a film by sputtering or CVD, and a Cu wiring pattern is processed. Further, if necessary, W is thinly coated around the Cu wiring by selective CVD of W. Thereafter, the surface of W is irradiated with nitrogen plasma to form a surface nitrided layer.
[0023]
Next, in the wiring structure of the second semiconductor integrated circuit of the present invention, a barrier layer is formed in which at least one layer of a metal film and a metal metal nitride film constituting the metal film is formed. Yes. When a metal nitride film was formed by plasma irradiation, the crystal structure was found to be almost completely amorphous by examining the crystal structure by X-ray diffraction. On the other hand, a film formed by another method such as reactive sputtering or CVD is generally a crystalline metal nitride film. Therefore, the metal nitride film formed by plasma irradiation is more effective in suppressing the grain boundary diffusion of Cu, Au, and Ag into the insulating film and the substrate. In the case of W nitride, a film close to an amorphous state can be obtained by reactive sputtering depending on conditions. However, this film is a W-rich film having a composition ratio of W and N of 2 to 4. On the other hand, by plasma irradiation, a film having a composition ratio close to 1 (1 ± 0.2) can be obtained. Such a nitrided W film has a particularly high barrier property. Further, the surface of the metal film is nitrided by plasma nitriding, and the barrier layer surface is flattened by the sputtering effect of the film surface by plasma. Thereby, the flatness of the Cu film formed on the surface of the barrier layer is also improved, and the defect rate of the pattern shape in the patterning process is remarkably improved.
[0024]
Here, W, Ta, and Ta—W alloy are chemically stable as compared with other metals, and the reaction with Cu, Au, and Ag by heat treatment is very small, and an increase in the specific resistance of the wiring is suppressed. be able to. Moreover, when the elements described in the above (4) to (6) are added, an improvement in barrier performance as well as an improvement in film density is recognized.
In addition, since the nitride layer obtained by plasma irradiation is as thin as 100 mm or less, in order to further improve the barrier performance, the entire barrier layer is formed by repeating the deposition of the W film, the Ta film, or the Ta—W alloy layer and the plasma nitridation. By increasing the ratio of the nitride film, the diffusion barrier effect of Cu, Au, and Ag can be remarkably improved.
[0025]
In addition, when the barrier layer has a multilayer structure, the unevenness of the barrier film surface due to crystal grain growth can be reduced as compared with the single layer structure. For this reason, combined with the sputtering effect on the film surface described above, the flatness of the metal film formed on the barrier film surface is further improved, and the defect rate of the pattern shape in the patterning process is significantly improved. As a result, it is possible to cope with advanced wiring processing technology (patterning technology) required in a fine wiring structure of 0.25 μm or less.
[0026]
Further, the nitrides, borides, and carbides of Ta—W alloy, Ta—W alloy, Ta alloy, and W alloy used in the wiring structures of the third to sixth semiconductor integrated circuits of the present invention are: It is chemically stable as compared with Ta-W alloy, Ta-W alloy, Ta alloy, and W alloy, and the reaction with Cu, Au, and Ag during heat treatment is very small. Since the alloy film generally has finer crystal grains than the pure metal film, a more uniform amorphous nitride film can be formed by plasma nitriding, for example. In addition, recrystallization due to heat treatment after formation hardly occurs. For this reason, when these nitrides, borides, and carbides are used as diffusion preventing barriers for wirings made of metals selected from Cu, Cu alloys, Au, Au alloys, Ag, Ag alloys, and Al-Cu alloys, they are excellent. Exhibits diffusion prevention effect.
[0027]
Also, according to the method for manufacturing a wiring structure of a semiconductor integrated circuit of the present invention, a plasma metal nitride thin film is formed by irradiating the surface of the metal film with plasma. Can be uniformly formed. Therefore, the substantial nitride film thickness can be kept low, and the wiring resistance is extremely low. Note that it is difficult to uniformly form such a thin nitride film by controlling the film thickness by reactive sputtering or the like.
[0028]
Here, when the above manufacturing method is applied to a wiring structure made of Cu, Au, Ag, Cu alloy, Au alloy, Ag alloy, or Al—Cu alloy, an insulating film is formed with a plasma metal nitride thin film while keeping the wiring resistance low. In addition, it is possible to obtain a barrier effect that the diffusion of Cu, Au, Ag to the substrate is satisfactorily suppressed.
[0029]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[First embodiment]
Table 1 shows experimental results comparing the barrier properties of various barrier materials against Cu. In this experiment, in order to compare and examine the barrier properties of a film having a laminated structure, films of various structures were formed on a silicon substrate, a Cu film was formed, and after diffusion heat treatment, the silicon substrate surface was reached. The concentration of Cu is measured by SIMS (Secondary Ion Mass Spectroscopy).
[0030]
Each sample is formed by depositing a total of 600 バ リ ア of barrier film on a silicon substrate and further depositing 5,000 銅 of copper on the barrier film by RF magnetron sputtering. After formation, each sample was heat-treated at 500 ° C. for 1 h in a hydrogen gas atmosphere, and the copper concentration on the silicon substrate surface was measured. From Table 1, it can be seen that the barrier layer having a multilayer structure has a remarkably excellent barrier effect against copper diffusion. In particular, it can be seen that a multilayer structure including an amorphous nitride film is excellent in barrier properties. Furthermore, it can be seen that a multilayer structure including an amorphous W nitride film formed by plasma nitriding is excellent in barrier properties.
[0031]
[Table 1]

[0032]
Next, an example of the wiring structure and the manufacturing method thereof according to the present invention will be described with reference to FIGS. As shown in FIG. 1, an insulating film 12 of 5000 BPSG (borophosphosilicate glass) is formed on the surface of the silicon substrate 10. As shown in FIG. 2, a tungsten film 14 is formed on the entire surface of the insulating film 12 by RF magnetron sputtering in an argon atmosphere at a total pressure of 2 mTorr and a film formation rate of 10 Å / s. Next, as shown in FIG. 3, the surface of the tungsten film 14 is irradiated with ECR plasma having a microwave power of 600 W at a nitrogen gas pressure of 1 mTorr and a nitrogen flow rate of 20 sccm for 60 seconds. About 20 cm of film 16 is formed. Next, as shown in FIG. 4, a copper film 18 is formed on the surface of the amorphous W—N film 16 by RF magnetron sputtering at a total pressure of 2 mTorr and a deposition rate of 60 Å / s in an argon atmosphere. Thereafter, as shown in FIG. 5, the copper film 18, the W—N film 16, and the tungsten film 14 are patterned to form a copper wiring 20. After that, as shown in FIG. 6, tungsten is selectively grown only on the outer surfaces of the copper wiring 20, the W-N film 16, and the tungsten film 14 by CVD to form a tungsten coating film 22. . The tungsten coating film 22 is formed by setting the sample temperature to 200 ° C. to 400 ° C., supplying a mixed gas of tungsten hexafluoride gas and hydrogen gas to the film forming chamber, and setting the gas pressure to 1 Torr or less. According to this film forming method, the interface reaction becomes rate-limiting, and tungsten can be selectively grown only on the outer surfaces of the copper wiring 20, the W—N film 16, and the tungsten film 14. Finally, as shown in FIG. 7, the surface of the CVD tungsten film is again irradiated with ECR plasma with a nitrogen gas pressure of 1 mTorr, a nitrogen flow rate of 20 sccm, and a microwave output of 600 W for 60 seconds. About 20 cm.
[0033]
Here, in order to make this wiring structure multi-layered, on the amorphous W-N film 24, ordinary SiO₂ The above-described wiring structure may be manufactured by the same method on the insulating film.
The film thickness of the plasma nitride film can be controlled by changing plasma power, acceleration voltage, substrate temperature, and the like. When ECR plasma is used, a W—N film of about 20 mm can be formed in a nitriding time of 40 seconds or more under the conditions of no acceleration, plasma power of 600 W, and substrate temperature of room temperature. This film thickness hardly increased even when the nitriding time was increased to 5 minutes. Further, it was confirmed by AES (Auger Electron Spectroscopy) that the composition ratio between W atoms and N atoms contained in this film was close to 1 (1 ± 0.2).
[0034]
By increasing the substrate temperature to 100 ° C., the WN film thickness could be increased to 50 ° C., and further to 200 ° C., to 100 ° C. However, when the thickness was 50 mm or more, the barrier property was not significantly improved. On the other hand, the wiring resistance increased slightly as the W film thickness decreased. Furthermore, at a substrate temperature of 200 ° C., the WN film thickness could be increased up to 150 mm by applying an acceleration voltage of 200 V to the substrate. However, when the film thickness exceeded 100 mm, a rough metal nitride film was formed, and the barrier properties deteriorated.
[0035]
On the other hand, a thinner WN film can be obtained by reducing the plasma power or shortening the irradiation time to 40 seconds or less. For example, the WN film thickness could be reduced to 8% at a plasma power of 200 W and a nitriding time of 10 seconds. However, when the film thickness was less than 10 mm, the barrier property was remarkably lowered.
Therefore, the W-N film thickness is preferably in the range of 10 to 100 mm, more preferably in the range of 10 to 50 mm.
[0036]
As a method of generating plasma used for nitriding, a method capable of generating high-density plasma is desirable because the surface of the metal film is nitrided within a practical time. With normal high frequency plasma of 13.56 MHz, conditions for obtaining a sufficient W—N film thickness within a practical nitriding time could not be found. In normal high-frequency plasma, the plasma density is 1 × 10^Tencm^-3This can be interpreted as a low degree. In contrast, ECR 5x10^Tencm^-3Since the above high plasma density can be obtained, it can be interpreted that a WN film having a sufficient thickness can be obtained by nitriding in a short time of 40 seconds.
[0037]
As a plasma generation method capable of obtaining a high-density plasma as in ECR, helicon plasma, ICP (Inductively Coupled Plasma), TCP (Transformer Coupled Plasma), and the like can be suitably used.
In addition, a barrier layer having a laminated structure in which the surface of a W-Ta alloy, a Ta alloy in which Mo, Nb, and Ti are added to Ta, or a W alloy in which Mo, Nb, Pd, and Pb are added to W is nitrided By using it, higher barrier properties can be obtained.
[0038]
[Second Embodiment]
A method for manufacturing a wiring structure using Nb and plasma nitrided Nb as a barrier material will be described with reference to FIGS.
As shown in FIG. 8, an insulating film 32 of 5,000 BPSG (borophosphosilicate glass) is formed on the surface of the Si substrate 30, and an Nb crystalline film 34 is formed on the surface of the insulating film 32. The Nb crystalline film 34 was grown at 1000 Å at a film formation rate of 10 Å / s by RF magnetron sputtering in an Ar atmosphere with a total pressure of 2 mTorr. After that, Nb crystalline film 34 has N₂ The surface of the Nb crystalline film 34 was nitrided by irradiating ECR plasma with a gas pressure of 1 mTorr (flow rate 20 sccm) and an output of 400 W for 60 seconds to form a plasma nitrided Nb thin film (Nb-N) 34a. A Cu film 36 was formed on the surface of this plasma nitrided Nb thin film 34a by RF magnetron sputtering in an Ar atmosphere of 2 mTorr, and these were patterned to form a Cu wiring 36a as shown in FIG. FIG. 10 is an enlarged view showing a Cu wiring 36a and a base film of the Cu wiring 36a. An amorphous Nb thin film 34a is formed on the Nb crystalline film 34 by plasma irradiation. Note that. Even when an Al—Cu alloy film is formed instead of the Cu film 36, the Nb—N / Nb layered film is effective for preventing diffusion of Cu in the Al—Cu alloy film.
[Third embodiment]
Here, an example of the wiring structure will be described together with a comparative example.
[0039]
Table 2 shows an example using the Nb crystalline film and the plasma nitrided Nb thin film (Nb-N) formed by the above method, a comparative example in which 1000 Ｔｉ Ti-N was formed as a base by sputtering, and the base as an insulating film. It is the value of the wiring resistance for each of the comparative examples that are left as they are. The sample is deposited so that the total thickness of the Al—Cu alloy wiring and the base film is 10,000 mm, and the thickness of the plasma nitrided Nb thin film is in the range of 25 mm to 50 mm.
[0040]
Table 3 shows SIMS (Secondary-Ion Mass Spectroscopy Secondary Ion Mass Spectrometry) barrier properties against Cu in the examples using the plasma metal nitride thin films prepared by the above method and the comparative examples using various base materials. It is the result evaluated by. The sample is a 1000-thick Cu film deposited on the substrate.₂ The heat treatment (temperature increase rate: 100 ° C./h) was performed in an atmosphere at 600 ° C. × 1 h, and the Cu concentration in the Si wafer was compared by obtaining the Cu depth profile using SIMS. .
[0041]
[Table 2]

[0042]
[Table 3]

[0043]
As shown in Tables 2 and 3, when the base surface is plasma-nitrided and a plasma metal nitride thin film is formed as in this embodiment as compared to the metal films and nitride films proposed so far, the wiring resistance is increased. It can be suppressed and the diffusion of Cu can be significantly reduced.
[Fourth embodiment]
Next, another embodiment of the wiring structure will be described together with a comparative example.
[0044]
Table 4 shows a comparison between the barrier properties of various barrier layers having the same thickness with respect to Cu, after diffusion heat treatment of a Cu / M / Si (M represents various barrier layers) laminated film, Cu concentration is changed to SIMS (Secondary-Ion Mass
It is the result measured by Spectroscopy.
[0045]
[Table 4]

[0046]
In the sample of the comparative example, first, 600 Å of a single-layer barrier film was deposited on the Si substrate by RF magnetron sputtering. On the other hand, in the sample of the example, first, a metal film is formed on a Si substrate by RF magnetron sputtering, and a plasma metal nitride thin film is formed on the surface of the metal film by an ECR plasma nitridation method as a first layer. A metal film and a plasma metal nitride thin film were sequentially formed on the layer by the above method to form a multilayer barrier layer having a thickness of 600 mm. Furthermore, on the surfaces of the samples of these comparative examples and examples, Cu was laminated by 5000 m by RF magnetron sputtering to form a multilayer film, and these samples on which this multilayer film was formed were subjected to H₂ A heat treatment of 640 ° C. × 1 h was performed in a gas atmosphere, and then the Cu concentration on the Si surface was measured using SIMS and compared. As is clear from Table 3, the Cu concentration on the Si surface is significantly reduced in the barrier layer of the example as compared with the conventional barrier films of Cr, Mo, TiN, etc., and the effectiveness of the present invention can be clearly seen. .
[0047]
Next, referring to FIG. 11 to FIG. 13, wiring in which a barrier layer is formed by stacking six layers of the W film and the plasma nitrided W thin film (W-N / W) in Table 4 above. A method for forming the structure will be described. As shown in FIG. 11, an insulating film 42 of 5000 BPSG (borophosphosilicate glass) is formed on the surface of the Si substrate 40, and a W film is formed on the entire surface of the insulating film 42 in an Ar gas atmosphere with a total pressure of 2 mTorr. Then, 100 Å is grown at a film formation rate of 10 Å / s by RF magnetron sputtering. On the surface of the W film, N₂ By irradiating ECR plasma with a gas pressure of 1 mTorr and a plasma output of 400 W for 60 s, the surface of the W film is nitrided to form a plasma nitride film, thereby forming a layer composed of the W film and the plasma nitrided W thin film. On this layer, a multilayer barrier layer 44 having a thickness of 600 mm is formed by repeating the above method. On the surface of the barrier layer 44, a Cu film 46 is grown by 5000 nm at a film forming rate of 60 mm / s by RF magnetron sputtering in an Ar gas atmosphere having a total pressure of 2 mTorr. Thereafter, as shown in FIG. 12, the barrier layer 44 and the Cu film 46 are patterned to form a base film 44a and a wiring 46a. Thereafter, as shown in FIG. 13, W is grown by 400 nm only on the outer surfaces of the base film 44a and the wiring 46a by the CVD method to form a W coating film 48. The W coating film 48 has a sample temperature of 200 to 400 ° C.₆ And H₂ The mixed gas is supplied to the film forming chamber, and the pressure of the mixed gas is set to 1 Torr or less. According to this film forming method, the interface reaction becomes rate limiting, and W can be selectively grown only on the outer surfaces of the base film 44a and the wiring 46a. Here, in order to make this wiring structure multilayer, on the W coating film 48, SiO₂ An insulating film such as a film may be formed, and the wiring structure described above may be formed on the insulating film by a similar method.
[Fifth embodiment]
First, Table 5 to Table 7 show experimental results comparing the barrier properties of various materials against Cu. In this experiment, in order to compare the barrier properties of various materials, a Cu / M / Si multilayer film (M represents various barrier film materials) was formed, subjected to diffusion heat treatment, and then the Cu concentration on the Si surface was measured by SIMS. It is measured by (Secondary-Ion Mass Spectroscopy secondary ion mass spectrometry).
[0048]
These multilayer films are N₂ Using a mixed gas of Ar and Ar or Ar gas, 600 nm of a barrier material alloy film is deposited on the Si substrate by RF magnetron sputtering. Further, 5000 mm of Cu is deposited on the barrier material alloy film by RF magnetron sputtering of Ar gas. Formed. After that, these multilayer films are formed with H₂ A heat treatment of 650 ° C. × 1.5 h was performed in a gas atmosphere, and the Cu concentration on the surface of the Si substrate was measured and compared using SIMS.
[0049]
[Table 5]

[0050]
[Table 6]

[0051]
[Table 7]

[0052]
As is apparent from Tables 5 to 7, it can be clearly seen that nitrides, borides, and carbides of various alloys have an excellent barrier effect as compared with conventional barrier materials.
Next, an example of a wiring structure and a method for manufacturing the same according to the present invention will be described with reference to FIGS.
As shown in FIG. 14, an insulating film 52 of 5000 BPSG (borophosphosilicate glass) is formed on the surface of the Si substrate 50, and Ta insulating film 52 is formed on the entire surface of this insulating film 52.₁₅W₈₀Mo_Five -N film 54 (Ta₁₅W₈₀Mo_Five -N represents a nitride of an alloy composed of 15 at% Ta, 80 at% W, and 5 at% Mo. ), 50% Ar with a total pressure of 2 mTorr, N₂ The film is grown at 600 Å at a film forming rate of 10 Å / s by RF magnetron sputtering in a 50% gas atmosphere. This Ta₁₅W₈₀Mo_Five A Cu film 56 is grown on the surface of the -N film 54 at a deposition rate of 60 Å / s by RF magnetron sputtering in an Ar gas atmosphere with a total pressure of 2 mTorr. Then, as shown in FIG.₁₅W₈₀Mo_Five The base film 54a and the Cu wiring 56a are formed by patterning the -N film 54 and the Cu film 56. Then, as shown in FIG. 16, W is selectively grown on the outer surfaces of the base film 54a and the Cu wiring 56a by a CVD method to form a W coating film 58. The W coating film 58 has a sample temperature of 200 to 400 ° C.₆ And H₂ The mixed gas is supplied to the film forming chamber, and the gas pressure of the mixed gas is set to 1 Torr or less. According to this film forming method, the interface reaction becomes rate-limiting, and W can be selectively grown only on the outer surfaces of the base film 54a and the Cu wiring 56a. Here, in order to make this wiring structure multi-layered, SiO layer is formed on the W coating layer 58.₂ An insulating film such as the above may be provided, and the wiring structure described above may be formed on the insulating film by a similar method.
[0053]
【The invention's effect】
As described above, according to the first wiring structure of the present invention, since the barrier layer composed of at least one laminate of the metal film and the metal compound film is used as the base or covering of the wiring, the wiring resistance is not increased. Cu diffusion could be prevented, and a highly reliable semiconductor wiring structure could be realized. Therefore, the industrial significance of the present invention is very great. When the present invention is applied to a Cu wiring, diffusion of Cu can be prevented without increasing the resistance of the Cu wiring, and a semiconductor wiring structure having excellent reliability can be realized.
[0054]
In the second wiring structure of the present invention, a barrier layer in which at least one layer made of a metal film and a metal metal thin film constituting the metal film is formed is formed on the surface of the barrier layer. The flatness of the formed Cu film is improved, and the defect rate of the pattern shape in the patterning process is remarkably improved.
In the wiring structures of the semiconductor integrated circuits of the third to sixth aspects of the present invention, Ta—W alloy, Ta—W alloy, Ta alloy, W alloy nitride, boride having good barrier properties are provided. Since the carbide is used as the base and / or coating of the Cu wiring, a wiring structure in which Cu diffusion is sufficiently suppressed can be realized. Therefore, according to the present invention, it is possible to realize a Cu wiring having a very large industrial significance and having a specific resistance smaller than that of Al and excellent in electromigration resistance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a method of manufacturing a wiring structure according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the method for manufacturing the wiring structure according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view showing the method for manufacturing the wiring structure according to the first embodiment of the present invention.
FIG. 4 is a cross-sectional view showing the method for manufacturing the wiring structure according to the first embodiment of the present invention.
FIG. 5 is a cross-sectional view showing the method for manufacturing the wiring structure according to the first embodiment of the present invention.
FIG. 6 is a cross-sectional view showing the method for manufacturing the wiring structure according to the first embodiment of the present invention.
FIG. 7 is a cross-sectional view showing the method for manufacturing the wiring structure according to the first embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a method for manufacturing a wiring structure according to a second embodiment of the present invention.
FIG. 9 is a cross-sectional view showing a method for manufacturing a wiring structure according to a second embodiment of the present invention.
FIG. 10 is a cross-sectional view showing a method for manufacturing a wiring structure according to a second embodiment of the present invention.
FIG. 11 is a cross-sectional view showing a method for manufacturing a wiring structure according to a fourth embodiment of the present invention.
FIG. 12 is a cross-sectional view showing a method for manufacturing a wiring structure according to a fourth embodiment of the present invention.
FIG. 13 is a cross-sectional view showing a method for manufacturing a wiring structure according to a fourth embodiment of the present invention.
FIG. 14 is a cross-sectional view showing a method for manufacturing a wiring structure according to a fifth embodiment of the present invention.
FIG. 15 is a cross-sectional view showing a method for manufacturing a wiring structure according to a fifth embodiment of the present invention.
FIG. 16 is a cross-sectional view showing a method for manufacturing a wiring structure according to a fifth embodiment of the present invention.
[Explanation of symbols]
10, 30, 40, 50 Si substrate
12, 32, 42 Insulating film
14 Tungsten film
16,24 Amorphous WN_X film
18, 36, 46 Cu film
20, 36a, 46a Cu wiring
22 Tungsten coating film
34 Nb crystalline film
34a Plasma nitrided Nb thin film
44 Barrier layer
44a Underlayer

Claims (19)

In a wiring structure of a semiconductor integrated circuit including a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al—Cu alloy,
A barrier layer composed of at least one laminate composed of a Ta film and a Ta nitride film having a thickness in the range of 10 to 100 mm formed on the surface of the Ta film, A wiring structure for a semiconductor integrated circuit, comprising: The wiring covering is a barrier layer made of a laminate composed of a Ta film in contact with the wiring on a side surface of the wiring and a Ta nitride film formed outside the Ta film. Item 14. A semiconductor integrated circuit wiring structure according to Item 1. 3. The wiring structure of a semiconductor integrated circuit according to claim 1, wherein the upper limit of the thickness of the Ta nitride film is 50 mm. 4. The wiring structure for a semiconductor integrated circuit according to claim 1, wherein the wiring is made of a metal selected from Cu and a Cu alloy. The wiring structure of a semiconductor integrated circuit according to claim 1, wherein the wiring is made of Cu. 6. The wiring structure for a semiconductor integrated circuit according to claim 1, wherein the barrier layer is provided as a base for the wiring layer. 7. The nitride film according to claim 1, wherein the Ta nitride film is amorphous.
A wiring structure of a semiconductor integrated circuit according to any one of the above. In a wiring structure of a semiconductor integrated circuit including wiring made of Cu,
  A barrier layer composed of at least one laminate composed of a Ta film and a Ta nitride film formed on the surface of the Ta film and having a thickness within a range of 10 to 100 mm is provided as a base of the wiring. A wiring structure for a semiconductor integrated circuit. 9. The wiring structure of a semiconductor integrated circuit according to claim 8, wherein the upper limit of the thickness of the Ta nitride film is 50 mm. In a wiring structure of a semiconductor integrated circuit including a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, and Ag alloy,
  A metal film selected from a Ta film, a W film, and a Ta-W alloy film, and a metal film that is formed on the surface of the metal film and has a thickness in the range of 10 to 100 mm. A wiring structure of a semiconductor integrated circuit, comprising a barrier layer made of at least one laminate composed of a metal nitride film as a base and / or covering of the wiring. The wiring covering comprises a metal film selected from a Ta film, a W film, and a Ta—W alloy film in contact with the wiring on the side surface of the wiring, and the metal film formed outside the metal film. 11. The wiring structure for a semiconductor integrated circuit according to claim 10, wherein the wiring layer is a barrier layer made of a laminate composed of a metal nitride film of a metal to be used. 12. The wiring structure for a semiconductor integrated circuit according to claim 10, wherein the upper limit of the thickness of the metal nitride film is 50 mm. 13. The wiring structure for a semiconductor integrated circuit according to claim 10, wherein the wiring is made of a metal selected from Cu and a Cu alloy. 14. The wiring structure for a semiconductor integrated circuit according to claim 10, wherein the wiring is made of Cu. 15. The wiring structure for a semiconductor integrated circuit according to claim 10, wherein the barrier layer is provided as a base for the wiring. 16. The wiring structure for a semiconductor integrated circuit according to claim 10, wherein the metal film is a Ta film and the metal nitride film is a Ta nitride film. In a wiring structure of a semiconductor integrated circuit having a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al—Cu alloy, a nitride of Ta—W alloy, A wiring structure for a semiconductor integrated circuit, comprising a barrier layer selected from a shelf and a carbide as a base and / or covering for the wiring. Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al- In a wiring structure of a semiconductor integrated circuit including a wiring made of a metal selected from a Cu alloy,
  A barrier layer selected from a nitride, boride, and carbide of a Ta-based alloy in which one or more metals selected from Mo, Nb, and Ti are added to Ta is used as a base and / or coating for the wiring. A wiring structure for a semiconductor integrated circuit, comprising: In a wiring structure of a semiconductor integrated circuit including a wiring made of a metal selected from Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, and Al—Cu alloy,
  A barrier layer selected from nitrides, borides, and carbides of a W-based alloy obtained by adding one or more metals selected from Mo, Nb, Pd, and Pb to W, A wiring structure for a semiconductor integrated circuit, characterized in that the wiring structure is provided as a coating.

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