JP3490317B2 - Copper thin film formation by chemical vapor deposition - Google Patents
Copper thin film formation by chemical vapor depositionInfo
- Publication number
- JP3490317B2 JP3490317B2 JP37060398A JP37060398A JP3490317B2 JP 3490317 B2 JP3490317 B2 JP 3490317B2 JP 37060398 A JP37060398 A JP 37060398A JP 37060398 A JP37060398 A JP 37060398A JP 3490317 B2 JP3490317 B2 JP 3490317B2
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- JP
- Japan
- Prior art keywords
- thin film
- film
- cvd
- barrier metal
- forming
- Prior art date
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- Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
- Chemical Vapour Deposition (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ＬＳＩ等のＩＣ製
造の際の銅薄膜形成法に関し、特に化学蒸着法で形成さ
れるＣｕ薄膜（ＣＶＤ−Ｃｕ薄膜）による配線埋め込み
工程のＣＶＤ−Ｃｕ薄膜の形成法、およびＣｕ電解メッ
キのためのシード層としてのＣＶＤ−Ｃｕ薄膜の形成法
に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a copper thin film in the manufacture of ICs such as LSIs, and more particularly to a CVD-Cu thin film in a wiring embedding process using a Cu thin film (CVD-Cu thin film) formed by chemical vapor deposition. And a method of forming a CVD-Cu thin film as a seed layer for Cu electrolytic plating.
【０００２】[0002]
【従来の技術】従来、ＣＶＤ法にてＣｕ薄膜を形成し、
Ｃｕ配線を形成する場合、直接バリアメタル膜上にＣｕ
薄膜を形成するか、またはバリアメタル膜上に厚さ２０
ｎｍ程度のＣｕ膜をスパッタ法にて形成した後、このス
パッタ−Ｃｕ膜上にＣｕ薄膜を形成していた。下地層と
してスパッタ−Ｃｕ膜を用いるＣＶＤ−Ｃｕ薄膜形成法
は、例えば特開平４−２４２９３７号公報に記載されて
いる。従来のＣｕ配線形成では、基板上に設けられた
シリコン酸化物（ＳｉＯ2）絶縁膜中に配線溝を形成
し、次いで絶縁膜中へのＣｕの拡散を防止するためにバ
リアメタル（ＴｉＮ、ＴａＮ、ＷＮ等）膜をスパッタま
たはＣＶＤ法にて形成し、その後、ＣＶＤ−Ｃｕ薄膜を
形成するか、またはＣＶＤ−Ｃｕ薄膜の形成前にこのＣ
ｕ薄膜との密着性を増強するためにバリアメタル膜上に
スパッタ−Ｃｕ膜を形成し、次いでその上にＣＶＤ−Ｃ
ｕ薄膜を形成するかした後、ＣＭＰ研磨することにより
配線を形成する方法が採用されていた。上記配線形成で
は、例えばＣＶＤ法で成膜した窒化チタン（ＣＶＤ−Ｔ
ｉＮ）や窒化タンタル（ＣＶＤ−ＴａＮ）薄膜をバリア
メタル膜として用いる場合には、成膜時に混入した炭素
やその他の有機残基を除去することが必要であるため、
バリアメタル膜形成後、熱アニールやプラズマアニール
を行い、次いでＣＶＤ−Ｃｕ薄膜の形成を行うのが通常
であった。このような後処理を行うことにより組成が安
定し、スパッタ膜と近い抵抗値まで低抵抗化することが
可能であった。2. Description of the Related Art Conventionally, a Cu thin film is formed by a CVD method,
When forming Cu wiring, Cu is directly formed on the barrier metal film.
Form a thin film or a thickness of 20 on the barrier metal film.
After forming a Cu film having a thickness of about nm by a sputtering method, a Cu thin film was formed on this sputter-Cu film. A CVD-Cu thin film forming method using a sputter-Cu film as an underlayer is described in, for example, Japanese Patent Application Laid-Open No. 4-242937. In the conventional Cu wiring formation, it was provided on the substrate.
A wiring groove is formed in a silicon oxide (SiO 2 ) insulating film, and then a barrier metal (TiN, TaN, WN, etc.) film is formed by sputtering or a CVD method in order to prevent diffusion of Cu into the insulating film. Then, a CVD-Cu thin film is formed, or this C is formed before the CVD-Cu thin film is formed.
A sputter-Cu film is formed on the barrier metal film to enhance the adhesion with the u thin film, and then CVD-C is formed on the sputter-Cu film.
A method of forming a wiring by forming a u thin film and then performing CMP polishing has been adopted. In the above wiring formation, for example, titanium nitride (CVD-T
When using iN) or tantalum nitride (CVD-TaN) thin film as a barrier metal film, it is necessary to remove carbon and other organic residues mixed during film formation.
After forming the barrier metal film, it is usual to perform thermal annealing or plasma annealing, and then to form a CVD-Cu thin film. By performing such a post-treatment, the composition was stable and it was possible to reduce the resistance to a resistance value close to that of the sputtered film.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、上記従
来法で形成されたバリアメタル膜上に直接ＣＶＤ−Ｃｕ
薄膜を形成する場合、ＣＶＤ−Ｃｕ薄膜とバリアメタル
膜との間の密着性は一般に劣悪であり、テープ剥離テス
トを行うと容易に剥離してしまうことが多い。特に、Ｃ
ｕと合金を形成しないＴａ系のバリアメタルに対しては
成膜後に熱処理を行っても密着性の改善効果は全く見ら
れない。さらに、かかるバリアメタル膜上ではＣｕの初
期核生成密度が小さく、まばらな核が成長して合体し、
成膜されるため、滑らかな平面形状を得ることは困難で
ある。The object of the invention is to be Solved However, the above-mentioned slave
Direct CVD-Cu on the barrier metal film formed by the conventional method
When forming a thin film, the adhesion between the CVD-Cu thin film and the barrier metal film is generally poor, and the tape peeling test often results in easy peeling. In particular, C
With respect to the Ta-based barrier metal that does not form an alloy with u, no effect of improving the adhesion can be seen even if the heat treatment is performed after the film formation. Further, on the barrier metal film, the initial nucleation density of Cu is small, and sparse nuclei grow and coalesce,
Since a film is formed, it is difficult to obtain a smooth planar shape.
【０００４】また、ＣＶＤ法でバリアメタル膜を形成し
た後に上記のような熱アニール等の後処理をした場合、
スパッタ法により成膜したバリアメタル膜の場合と同
様、ＣＶＤ−Ｃｕ薄膜との密着性が悪化し、後のＣＭＰ
工程に耐えられなくなるという問題がある。この密着性
の問題を改善するために、前記したように、ＣＶＤ−Ｃ
ｕ薄膜の形成前にバリアメタル膜上に薄いスパッタ−Ｃ
ｕ膜を形成することが提案されているが、この方法では
密着性改善には有効ではない。なぜならば、スパッタ法
では被成膜面の幾何形状によりその膜厚が異なり、配線
溝幅が小さくなると、深い穴、溝の側面部および底面部
への成膜が不完全となり、十分な膜厚を得ることができ
ないからである。このように側面部および底面部で密着
性改善に役立つ膜厚が得られないことのみならず、フィ
ールド部（穴、溝の上部平面）ではＣｕ膜が厚いため、
その後のＣＶＤ−Ｃｕ薄膜の形成工程においてフィール
ド部で選択的にＣＶＤ−Ｃｕの核形成が行われてしま
い、側面部および底面部の被覆性が悪い要因ともなる。
また、側面部のスパッタ−Ｃｕ膜は入射角が浅いために
粒状に凝集するので、その上に成膜されるＣＶＤ−Ｃｕ
薄膜も荒れた平面形状を持つ膜となる。本発明は、上記
のような従来プロセスの問題点を解決するもので、優れ
た密着性と平滑な平面形状とを併せ持つＣＶＤ−Ｃｕ薄
膜の形成法を提供することを課題とする。When the barrier metal film is formed by the CVD method and the post-treatment such as the above-mentioned thermal annealing is performed,
Similar to the case of the barrier metal film formed by the sputtering method, the adhesion with the CVD-Cu thin film deteriorates, and CMP
There is a problem that the process cannot be endured. In order to improve this adhesion problem, as described above, CVD-C
u Thin sputter-C on barrier metal film before thin film formation
It has been proposed to form a u film, but this method is not effective in improving adhesion. This is because in the sputtering method, the film thickness varies depending on the geometric shape of the film formation surface, and if the wiring groove width becomes smaller, the film formation on the deep hole, the side surface portion and the bottom surface portion of the groove becomes incomplete, and the film thickness is sufficient. Because you can't get. As described above, not only is it impossible to obtain a film thickness that is useful for improving adhesion at the side surface portion and the bottom surface portion, but since the Cu film is thick at the field portion (the upper flat surface of the hole or groove),
In the subsequent CVD-Cu thin film forming step, the CVD-Cu nuclei are selectively formed in the field portion, which may be a cause of poor coverage of the side surface portion and the bottom surface portion.
Further, since the incident angle of the sputter-Cu film on the side surface portion is shallow, the sputter-Cu film is agglomerated in a granular form.
The thin film also has a rough planar shape. The present invention solves the problems of the conventional process as described above, and an object thereof is to provide a method for forming a CVD-Cu thin film having both excellent adhesion and a smooth planar shape.
【０００５】[0005]
【課題を解決するための手段】本発明のＣＶＤ−Ｃｕ薄
膜形成法は、絶縁膜中へのＣｕの拡散を防止するバリア
メタル膜がスパッタ法により形成された基板上に、有機
金属原料を用いて所定の厚さのＴｉＮ薄膜（ＣＶＤ−Ｔ
ｉＮ薄膜）またはＴａＮ薄膜（ＣＶＤ−ＴａＮ薄膜）を
密着増強層としてＣＶＤ法により薄く形成した後、引き
続きその上にＣｕ薄膜を化学蒸着法により形成させる方
法である。この密着増強層は薄く形成されるので、Ｔｉ
Ｎ、ＴａＮに対して低抵抗化処理を行う必要はない。上
記ＴｉＮ薄膜のＣＶＤ用原料である有機チタン材料とし
ては、例えば Ｔｉ[Ｎ-(ＣＨ3)2]4（ＴＤＭＡＴ）、Ｔ
ｉ[Ｎ-(Ｃ2Ｈ5)2]4（ＴＤＥＡＴ）、Ｔｉ[Ｎ-(ＣＨ3)(i
-Ｃ3Ｈ7)]4（ＴｉＰＭＡＴ）または これらの組合せが
挙げられ、これらを単独で用いて成膜しても、ＮＨ3ガ
スを 添加したものを用いて成膜してもよい。また、Ｔ
ａＮ薄膜のＣＶＤ用原料である有機タンタル材料として
は、例えばＴａ[Ｎ-(ＣＨ3)2]5、Ｔａ[[Ｎ-(ｔ-Ｃ4Ｈ9)
2]2[Ｎ-(Ｃ2Ｈ5)2]3] またはこれらの組合せが挙げられ
る。また、Ｃｕ薄膜のＣＶＤ用原料としては、例えばヘ
キサフルオロアセチルアセトナト銅ビニルトリメチルシ
ラン[ＣｕI(ＨＦＡＣ)ＶＴＭＳ]またはビスヘキサフル
オロアセチルアセトナト銅[ＣｕII(ＨＦＡＣ)2]が挙げ
られる。CVD-Cu thin film forming method of the present invention SUMMARY OF THE INVENTION may, Cu diffusion barrier metal film is more formed board on the sputtering preventing of the insulating film, an organic metal source Using a TiN thin film (CVD-T
In this method, an iN thin film) or a TaN thin film (CVD-TaN thin film) is thinly formed as an adhesion enhancing layer by a CVD method, and then a Cu thin film is formed thereon by a chemical vapor deposition method . Since this adhesion enhancing layer is thinly formed,
It is not necessary to reduce the resistance of N and TaN. Examples of the organic titanium material that is a raw material for CVD of the TiN thin film include Ti [N- (CH 3 ) 2 ] 4 (TDMAT), T
i [N- (C 2 H 5 ) 2 ] 4 (TDEAT), Ti [N- (CH 3 ) (i
-C 3 H 7 )] 4 (TiPMAT) or a combination thereof, and these may be used alone to form a film, or may be formed using a material to which NH 3 gas is added. Also, T
Examples of the organic tantalum material which is a raw material for CVD of the aN thin film include Ta [N- (CH 3 ) 2 ] 5 and Ta [[N- (t-C 4 H 9 ).
2 ] 2 [N- (C 2 H 5 ) 2 ] 3 ] or a combination thereof. In addition, examples of the raw material for CVD of the Cu thin film include hexafluoroacetylacetonato copper vinyltrimethylsilane [Cu I (HFAC) VTMS] or bishexafluoroacetylacetonato copper [Cu II (HFAC) 2 ].
【０００６】ＣＶＤ−ＴｉＮ薄膜、ＣＶＤ−ＴａＮ薄膜
の厚さは５０ｎｍ以下であることが望ましい。厚さが５
０ｎｍを超えると抵抗値増加の問題が生じるからであ
る。ＣＶＤ−ＴｉＮ、ＣＶＤ−ＴａＮ薄膜は高アスペク
ト比の穴、溝に対しても段差被覆性に優れているので、
スパッタ−Ｃｕ膜を密着増強層として用いた場合のよう
に、フィールド部と側・底面部との間に著しい膜厚差を
生じない。従って、反応律速領域のＣｕ薄膜用原料ガス
にとっては、全ての成膜面が均等でＣＶＤ−Ｃｕのコン
フォーマリティーが阻害されることはない。また、本発
明者らは、ＣＶＤ−ＴｉＮ薄膜またはＣＶＤ−ＴａＮ薄
膜の窒化物薄膜の表面にはＣｕの核形成を促進する効果
があることを見いだした。その作用機構は明らかでない
が、膜表面に析出したＴｉ、Ｔａ、または有機残基から
取り込まれる炭素が触媒作用を行っているものと思われ
る。いずれにせよ、本発明によれば、ＣＶＤ−ＴｉＮ薄
膜またはＣＶＤ−ＴａＮ薄膜表面でＣｕの核密度が増大
することから、平滑な、鏡面様の薄い連続膜を得ること
ができる。The thickness of the CVD-TiN thin film and the CVD-TaN thin film is preferably 50 nm or less. Thickness is 5
This is because if it exceeds 0 nm, a problem of increase in resistance value occurs. Since the CVD-TiN and CVD-TaN thin films have excellent step coverage even for holes and grooves with a high aspect ratio,
Unlike the case where the sputter-Cu film is used as the adhesion enhancing layer, there is no significant film thickness difference between the field portion and the side / bottom surface portion. Therefore, for the Cu thin film source gas in the reaction rate-determining region, all film-forming surfaces are uniform and the conformality of CVD-Cu is not hindered. Further, the present inventors have found that the CVD-TiN film or the surface of the nitride compound film of CVD-TaN thin film was found to be effective in promoting the nucleation of Cu. Although its mechanism of action is not clear, it is considered that Ti, Ta deposited on the surface of the film, or carbon incorporated from an organic residue performs a catalytic action. In any case, according to the present invention, the CVD-TiN thin film
Since the nucleus density of Cu is increased on the surface of the film or the CVD-TaN thin film, a smooth, mirror-like thin continuous film can be obtained.
【０００７】 本発明によれば、ＣＶＤ−Ｃｕ薄膜の密
着性も同時に改善される。これは、核密度の増大により
膜が微結晶化し、内部応力が減少すること、また、初期
核形成部分の密着性が高いためと考えられるが、膜の密
着性そのものに対する物理的解明が進んでいないので、
真の原因は不明である。本発明において用いる基板上に
形成されているバリアメタル膜としては、スパッタ法を
用いて成膜されたタンタル、窒化タンタル、タングステ
ン、窒化タングステン、チタンもしくは窒化チタン等の
金属膜、窒化金属膜、またはこれらの膜の複層膜が挙げ
られる。また、Ｃｕ薄膜を電解メッキのシード層として
使用する際、微細な配線孔に対応するにはＣｕ薄膜の膜
厚の薄いことが、また、メッキ液の濡れ性を保持するに
はＣｕ薄膜表面の平滑性が重要な因子となることから、
本発明により得られるＣＶＤ−Ｃｕ薄膜はシード層とし
ても優れている。According to the present invention, the adhesion of the CVD-Cu thin film is simultaneously improved. It is considered that this is because the film is microcrystallized due to the increase of the nucleus density, the internal stress is reduced, and the adhesiveness of the initial nucleation part is high, but the physical elucidation of the adhesiveness of the film itself is progressing. Because there is no
The true cause is unknown. As the barrier metal film formed on the substrate used in the present invention, a metal film such as tantalum, tantalum nitride, tungsten, tungsten nitride, titanium or titanium nitride formed by a sputtering method , a nitride film A metal film or a multilayer film of these films can be used. Further, when the Cu thin film is used as a seed layer for electrolytic plating, the Cu thin film should be thin in order to cope with fine wiring holes, and the Cu thin film surface should be kept wet to keep the plating solution wet. Since smoothness is an important factor,
The CVD-Cu thin film obtained by the present invention is also excellent as a seed layer.
【０００８】[0008]
【実施例】以下、本発明の実施例および比較例を図面を
参照して説明する。図１に示した真空成膜装置を使用し
て、本発明のＣｕ薄膜形成法を実施した。この装置は、
バリアメタル膜の形成された基板を格納するカセット室
１、ＣＶＤ−ＴｉＮ薄膜を形成するための反応室２、お
よびＣＶＤ−Ｃｕ薄膜を形成するための反応室３が、そ
れぞれ、仕切バルブ５、６、および７を介して、真空ロ
ボットを搭載した搬送室４と連結するように構成されて
いる。また、図１には示していないが、反応室２および
３は、基板を加熱するための適当な加熱手段と、Ｎ2、
Ｈ2、Ａｒ、Ｈｅ等のキャリアガス導入手段と、反応室
内を真空に排気するため の真空ポンプ等を具備し、反
応室２は、さらに、プラズマを発生する手段としての高
周波電源を具備している。EXAMPLES Examples and comparative examples of the present invention will be described below with reference to the drawings. The Cu thin film forming method of the present invention was carried out using the vacuum film forming apparatus shown in FIG. This device
A cassette chamber 1 for storing a substrate on which a barrier metal film is formed, a reaction chamber 2 for forming a CVD-TiN thin film, and a reaction chamber 3 for forming a CVD-Cu thin film are provided with partition valves 5 and 6, respectively. , And 7 are connected to the transfer chamber 4 in which the vacuum robot is mounted. Although not shown in FIG. 1, the reaction chambers 2 and 3 are provided with a suitable heating means for heating the substrate, N 2 ,
A carrier gas introducing means such as H 2 , Ar, and He and a vacuum pump for evacuating the reaction chamber to a vacuum are provided, and the reaction chamber 2 is further provided with a high frequency power source as a means for generating plasma. There is.
【０００９】配線溝の形成された絶縁膜（ＳｉＯ2膜
等）を有する基板で、スパッタ−ＴａＮバリアメタル膜
の形成された基板を、カセット室１から仕切バルブ５、
６を経て、先ず反応室２へ真空ロボットにより搬送し、
そこで該基板を４００℃に加熱して、６７Ｐａの圧力
下、ＴＤＭＡＴを３秒間流し、基板上に７〜８ｎｍのＣ
ＶＤ−ＴｉＮ薄膜を形成した。次いで、この基板を仕切
バルブ６、７を経て反応室３へ真空ロボットにより搬送
し、そこで基板温度を１７０℃に保持して、４００Ｐａ
の圧力下、ＣｕI(ＨＦＡＣ)ＶＴＭＳを流し、ＣＶＤ−
Ｃｕ薄膜を形成した。このＣＶＤ−Ｃｕ薄膜の成長の様
子を図２(Ａ)、(Ｂ)および(Ｃ)に模式的に示す。比較の
ために、反応室２でのＣＶＤ−ＴｉＮ薄膜の形成を行わ
ずに、スパッタ−ＴａＮバリアメタル膜の形成された基
板の上に直接ＣＶＤ−Ｃｕ薄膜を上記と同じ条件下で成
長させた場合、およびこのバリアメタル膜の上にスパッ
タ−Ｃｕ膜を形成し、次いでその上にＣＶＤ−Ｃｕ薄膜
を上記と同じ条件下で成長させた場合についても行っ
た。得られたＣＶＤ−Ｃｕ薄膜の成長の様子を、それぞ
れ、図３ならびに図４(Ａ)、(Ｂ)および(Ｃ)に模式的に
示す。An insulating film (SiO 2 film) in which wiring grooves are formed
A substrate having a sputter-TaN barrier metal film formed thereon is separated from the cassette chamber 1 by a partition valve 5,
Via 6, firstly transported to the reaction chamber 2 by a vacuum robot,
Therefore, the substrate is heated to 400 ° C., TDMAT is caused to flow for 3 seconds under a pressure of 67 Pa, and C of 7 to 8 nm is applied onto the substrate.
A VD-TiN thin film was formed. Next, this substrate is transferred to the reaction chamber 3 through the partition valves 6 and 7 by a vacuum robot, and the substrate temperature is maintained at 170 ° C. at 400 Pa.
Under pressure of Cu I (HFAC) VTMS, CVD-
A Cu thin film was formed. The growth of the CVD-Cu thin film is schematically shown in FIGS. 2 (A), (B) and (C). For comparison, the CVD-Cu thin film was directly grown on the substrate on which the sputter-TaN barrier metal film was formed without forming the CVD-TiN thin film in the reaction chamber 2 under the same conditions as above. In this case, a sputter-Cu film was formed on the barrier metal film, and a CVD-Cu thin film was grown on the sputter-Cu film under the same conditions as above. The growth state of the obtained CVD-Cu thin film is schematically shown in FIGS. 3 and 4 (A), (B) and (C), respectively.
【００１０】図２から明らかなように、本発明の場合、
配線溝１１の形成された ＳｉＯ2絶縁膜１２を有する基
板において（図２(Ａ)）、スパッタで成膜されたバリア
メタル膜１３をＣＶＤ−ＴｉＮ薄膜１４で被覆すること
で（図２(Ｂ)）、次の工程において被成膜面全体での均
等なＣｕの初期核の形成が促進され、平滑な平面形状を
持つＣｕ連続薄膜１５を得ることができた（図２
(Ｃ)）。かくして得られた微結晶薄膜はテープ剥離テス
ト（ＪＩＳ Ｈ ８６６１−８）による密着性試験の結
果、優れた密着性を有していることが分かった。これに
対し、図３から明らかなように、バリアメタル膜１３の
上に直接ＣＶＤ−Ｃｕ薄膜１６を成長させた場合、Ｃｕ
の初期核の分布は疎であるため、隣接した核同士の成長
合体によってＣｕ連続膜１６となる際、膜表面は必然的
に粗面となった（図３）。また、図４から明らかなよう
に、バリアメタル膜１３をスパッタ−Ｃｕ膜１７で被覆
した場合（図４(Ａ)および(Ｂ)）も、ＣＶＤ−Ｃｕ薄膜
１８の表面は、図３の場合と同様に疎面であった（図４
(Ｃ)）。As is apparent from FIG. 2, in the case of the present invention,
By covering the barrier metal film 13 formed by sputtering with the CVD-TiN thin film 14 on the substrate having the SiO 2 insulating film 12 in which the wiring groove 11 is formed (see FIG. 2 (B)). )), In the next step, formation of uniform initial nuclei of Cu on the entire film formation surface was promoted, and a Cu continuous thin film 15 having a smooth planar shape could be obtained (FIG. 2).
(C)). The microcrystalline thin film thus obtained was found to have excellent adhesiveness as a result of an adhesiveness test by a tape peeling test (JIS H 8661-8). On the other hand, as is clear from FIG. 3, when the CVD-Cu thin film 16 is directly grown on the barrier metal film 13, Cu
Since the distribution of the initial nuclei was sparse, the film surface inevitably became rough when the Cu continuous film 16 was formed by the growth coalescence of adjacent nuclei (FIG. 3). Further, as is clear from FIG. 4, even when the barrier metal film 13 is covered with the sputter-Cu film 17 (FIGS. 4A and 4B), the surface of the CVD-Cu thin film 18 is the case of FIG. It was a sparse surface similar to (Fig. 4
(C)).
【００１１】スパッタバリアメタル膜に直接ＣＶＤ−Ｃ
ｕ薄膜を形成した場合およびＣＶＤ−Ｃｕ薄膜の形成前
にバリアメタル膜上にスパッタ−Ｃｕ膜を形成した場
合、初期核は、１μｍ2当たり ５０〜２００個程度であ
ったのと較べ、バリアメタル膜上にＣＶＤ−ＴｉＮ薄膜
を形成した場合にはその１０倍以上の核が観測された。
本発明の場合、ＣｕI(ＨＦＡＣ)ＶＴＭＳを流し始めて
８秒後には 既に連続膜が形成され、その時の膜厚は約
２０ｎｍであり、得られたＣｕ薄膜は、従来技術により
直接ＣＶＤ−Ｃｕ薄膜を形成した場合およびスパッタＣ
ｕ膜を形成した場合と較べて、密着性が増すと共に膜面
は平滑化（鏡面化）していた。Direct CVD-C on sputter barrier metal film
When the u thin film was formed and when the sputter-Cu film was formed on the barrier metal film before forming the CVD-Cu thin film, the initial nuclei were about 50 to 200 per 1 μm 2 When the CVD-TiN thin film was formed on the film, 10 times or more nuclei were observed.
In the case of the present invention, a continuous film is already formed 8 seconds after starting the flow of Cu I (HFAC) VTMS, and the film thickness at that time is about 20 nm. The obtained Cu thin film is a direct CVD-Cu thin film by the conventional technique. And sputter C
As compared with the case where the u film was formed, the adhesion was increased and the film surface was smoothed (mirrored).
【００１２】次に、初期核密度ｎと膜粗さＳとの関係を
説明するために、その関係を表す簡単な数学的モデルの
説明図を図５に示す。数密度ｎ[個／μｍ2] の核間平均
距離ｄ（μｍ）は、ｄ〜１／ｎ1/2 である（図５
(Ａ)）。それぞれの核が接触角θを一定に保つように等
方的に成長すると仮定すると（図５(Ｂ)）、隣接した核
が合体する条件は核球の半径をａとした時、２ａ・ｓｉ
ｎθ≧ ｄで与えられる。この時、粗さＳは、Ｓ〜（１
／２ｎ1/2）・ｔａｎ(θ／２)（図５(Ｃ)）となる。θと
して７０゜、ｎとしてスパッタバリアメタル膜上の代表
値１００個／μｍ2 、ＣＶＤ−ＴｉＮ薄膜上の代表値２
０００個／μｍ2 を代入すると、Ｓ（スパッタバリアメ
タル）〜３５ｎｍ、Ｓ（ＣＶＤ−ＴｉＮ）〜８ｎｍを得
る。ＣＶＤ−ＴｉＮ薄膜を設けることにより、ＣＶＤ−
Ｃｕ薄膜の表面荒れが小さくなることが分かる。Next, in order to explain the relationship between the initial nucleus density n and the film roughness S, an explanatory view of a simple mathematical model showing the relationship is shown in FIG. The average internuclear distance d (μm) of the number density n [number / μm 2 ] is d to 1 / n 1/2 (FIG. 5).
(A)). Assuming that each nucleus grows isotropically so as to keep the contact angle θ constant (FIG. 5 (B)), the condition that the adjacent nuclei coalesce is 2a · si when the radius of the nuclear sphere is a.
It is given by nθ ≧ d. At this time, the roughness S is S to (1
/ 2n 1/2 ) · tan (θ / 2) (FIG. 5C). θ is 70 °, n is a typical value of 100 on the sputter barrier metal film / μm 2 , and typical value is 2 on the CVD-TiN thin film.
Substituting 000 / μm 2 , S (sputter barrier metal) to 35 nm and S (CVD-TiN) to 8 nm are obtained. By providing a CVD-TiN thin film, CVD-
It can be seen that the surface roughness of the Cu thin film is reduced.
【００１３】膜の表面荒れは、ＣＶＤ−Ｃｕ薄膜で溝
（または穴）部を埋め込む際に、溝（または穴）部の開
口部を閉塞させ、Ｃｕ配線部にボイドを生じせしめる原
因となる。また、ＣＶＤ−Ｃｕ薄膜をシード層としてＣ
ｕメッキを行う際も、メッキ液の濡れ性を阻害し、やは
り配線溝（穴）内部にボイドを生じせしめた。上記実施
例では、ＣＶＤ−ＴｉＮ薄膜形成のための有機チタン材
料としてＴＤＭＡＴを用いた場合を示したが、ＴＤＥＡ
Ｔ、ＴｉＰＭＡＴ、またはこれらの組合せを用いても、
また、ＣＶＤ−ＴａＮ薄膜形成のための有機タンタル材
料としてＴａ[Ｎ-(ＣＨ3)2]5、Ｔａ[[Ｎ-(ｔ-Ｃ4Ｈ9)2]
2[Ｎ-(Ｃ2Ｈ5)2]3] またはこれらの組合せを用いても同
様の効果が得られたことは言うまでもない。また、Ｃｕ
薄膜の形成のための原料としてＣｕI(ＨＦＡＣ)ＶＴＭ
Ｓの代わりにＣｕII(ＨＦＡＣ)2を用いた場合も同様な
結果が得られた。The surface roughness of the film causes the opening of the groove (or hole) to be closed when the groove (or hole) is filled with the CVD-Cu thin film, which causes a void in the Cu wiring part. Further, the CVD-Cu thin film is used as a seed layer for C.
Even when u-plating was performed, the wettability of the plating solution was hindered, and voids were also formed inside the wiring grooves (holes). Although TDMAT is used as the organic titanium material for forming the CVD-TiN thin film in the above embodiment, TDEA is used.
With T, TiPMAT, or a combination of these,
Further, Ta as the organic tantalum material <br/> cost for CVD-TaN thin film formation [N- (CH 3) 2] 5, Ta [[N- (t-C 4 H 9) 2]
Needless to say, the same effect was obtained by using 2 [N- (C 2 H 5 ) 2 ] 3 ] or a combination thereof. Also, Cu
Cu I (HFAC) VTM as a raw material for thin film formation
Similar results were obtained when Cu II (HFAC) 2 was used instead of S.
【００１４】 ＣＶＤ−Ｃｕ薄膜を形成する際、上述の
熱ＣＶＤ法の他、キャリアガスとしてＮ2、Ｈ2またはそ
の混合ガスを用い、ガスノズルに高周波電圧を印加して
プラズマを励起したＰＥＣＶＤ法、さらに熱ＣＶＤ法で
堆積した膜を上記ガス種のプラズマに暴露する方法など
種々の変形を試みた。いずれの場合にも、上記実施例の
場合と同様に密着性の改善と核形成密度の増大が確認さ
れた。また、上記実施例では、バリアメタル膜としてス
パッタ−ＴａＮ薄膜が形成された基板を用いた場合を示
したが、その他のバリアメタル膜、例えばスパッタ法を
用いて成膜されたＴａ、Ｗ、ＷＮ、ＴｉもしくはＴｉＮ
等の膜、またはそれらの膜の複層膜が形成された基板を
用いても同様の結果が得られることは言うまでもない。[0014] When forming the CVD-Cu film, other thermal CVD method described above, using N 2, H 2 or a mixed gas as a carrier gas, PECVD method using exciting plasma by applying a high frequency voltage to the gas nozzle, Further, various modifications such as a method of exposing the film deposited by the thermal CVD method to the plasma of the above gas species were tried. In each case, it was confirmed that the adhesion was improved and the nucleation density was increased as in the case of the above-mentioned examples. Further, in the above embodiment, the case where the substrate on which the sputter-TaN thin film is formed is used as the barrier metal film, but other barrier metal films, for example , Ta formed by using the sputtering method are shown. , W, WN, Ti or TiN
It is needless to say that the same result can be obtained by using a substrate on which the above films or a multi-layer film of these films are formed.
【００１５】[0015]
【発明の効果】本発明のＣｕ薄膜形成法によれば、スパ
ッタ法によりバリアメタル膜が形成されている基板にお
いて、ＣＶＤ−Ｃｕ薄膜形成の前に、有機金属材料を用
いて行うＣＶＤ法により、密着増強層としての金属窒化
物薄膜を形成してあるので、優れた密着性と平滑性を併
せ持つＣＶＤ−Ｃｕ薄膜を得ることができる。According to the Cu thin film forming method of the present invention, the spa
In the substrate on which the barrier metal film is formed by the sputtering method, the metal nitride thin film as the adhesion enhancing layer is formed by the CVD method using the organometallic material before the CVD-Cu thin film formation. A CVD-Cu thin film having both excellent adhesion and smoothness can be obtained.
【図１】本発明を実施するための真空成膜装置の構成の
一例を示す模式的構成図。FIG. 1 is a schematic configuration diagram showing an example of the configuration of a vacuum film forming apparatus for carrying out the present invention.
【図２】（Ａ）〜（Ｃ）本発明によるＣＶＤ−Ｃｕ薄膜
の成長プロセスを説明するための模式的断面図。2A to 2C are schematic cross-sectional views for explaining a growth process of a CVD-Cu thin film according to the present invention.
【図３】従来技術によるＣＶＤ−Ｃｕ薄膜の成長の様子
を示す模式的断面図。FIG. 3 is a schematic cross-sectional view showing a state of growth of a CVD-Cu thin film according to a conventional technique.
【図４】（Ａ）〜（Ｃ）従来技術によるＣＶＤ−Ｃｕ薄
膜の成長プロセスを説明するための模式的断面図。[4] (A) ~ (C) schematic cross-sectional view for explaining a growth process of a prior art CVD-Cu film.
【図５】（Ａ）〜（Ｃ）初期核密度ｎと膜粗さＳとの相
関をモデル化した説明図。[5] (A) ~ (C) illustrates a model of the correlation between the initial nuclei density n and Makuara of S.
１ カセット室 ２ 反応室
３ 反応室 ４ 搬送室
５、６、７ 仕切バルブ １１ 配線溝
１２ 絶縁膜 １３ バリアメ
タル膜
１４ ＣＶＤ−ＴｉＮ薄膜 １５、１６、１
８ ＣＶＤ−Ｃｕ薄膜
１７ スパッタ−Ｃｕ膜 ａ 核球の半
径
ｄ 核間平均距離 Ｓ 膜粗さ
θ 接触角DESCRIPTION OF SYMBOLS 1 cassette chamber 2 reaction chamber 3 reaction chamber 4 transfer chambers 5, 6, 7 partitioning valve 11 wiring groove 12 insulating film 13 barrier metal film 14 CVD-TiN thin film 15, 16, 1
8 CVD-Cu thin film 17 Sputter-Cu film a Radius of nuclear sphere d Average distance between nuclei S Film roughness θ Contact angle
フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ Ｈ０１Ｌ 21/285 ３０１ Ｈ０１Ｌ 21/88 Ｒ (56)参考文献 特開 平10−150039（ＪＰ，Ａ) 特開 平９−22907（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01L 21/3205 C23C 16/18 C23C 16/34 H01L 21/28 301 H01L 21/285 Continuation of the front page (51) Int.Cl. 7 identification code FI H01L 21/285 301 H01L 21/88 R (56) References JP 10-150039 (JP, A) JP 9-22907 (JP, A) (58) Fields surveyed (Int.Cl. 7 , DB name) H01L 21/3205 C23C 16/18 C23C 16/34 H01L 21/28 301 H01L 21/285
Claims (3)
された基板上に銅薄膜を化学蒸着法で形成する方法にお
いて、バリアメタル膜上に、有機チタン材料または有機
タンタル材料を用いて化学蒸着法により窒化チタン薄膜
または窒化タンタル薄膜を形成した後、引き続きその上
に銅薄膜を化学蒸着法により形成することを特徴とする
銅薄膜形成法。1. A method of forming a copper thin film on a substrate on which a barrier metal film is formed by a sputtering method by a chemical vapor deposition method, which comprises using an organic titanium material or an organic tantalum material on the barrier metal film by a chemical vapor deposition method. After forming a titanium nitride thin film or a tantalum nitride thin film, a copper thin film is subsequently formed thereon by a chemical vapor deposition method.
Ｈ3)2]4、Ｔｉ[Ｎ-(Ｃ2Ｈ5)2]4、Ｔｉ[Ｎ-(ＣＨ3)(i-Ｃ
3Ｈ7)]4またはこれらの組合せであり、前記有機タンタ
ル材料がＴａ[Ｎ-(ＣＨ3)2]5、Ｔａ[[Ｎ-(ｔ-Ｃ4Ｈ9)2]
2[Ｎ-(Ｃ2Ｈ5)2]3] またはこれらの組合せであることを
特徴とする請求項１記載の銅薄膜形成法。2. The organic titanium material is Ti [N- (C
H 3) 2] 4, Ti [N- (C 2 H 5) 2] 4, Ti [N- (CH 3) (i-C
3 H 7 )] 4 or a combination thereof, wherein the organic tantalum material is Ta [N- (CH 3 ) 2 ] 5 , Ta [[N- (t-C 4 H 9 ) 2 ].
2 [N- (C 2 H 5 ) 2] 3] or a copper thin film forming method according to claim 1 Symbol mounting characterized in that it is a combination thereof.
薄膜が厚さ５０ｎｍ以下の極薄膜であることを特徴とす
る請求項１または２記載の銅薄膜形成法。3. A copper thin film forming method according to claim 1 or 2, wherein said titanium film or a tantalum nitride thin nitride is less very thin film thickness of 50nm.
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