JP5680892B2 - Co film forming method - Google Patents
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Description
本発明は、基材表面にＣｏ膜を形成するためのＣｏ膜形成方法に関し、より詳しくは、Ｃｕ配線構造にてＣｏからなるシード層を形成する際に利用されるものに関する。 The present invention relates to a Co film forming method for forming a Co film on a substrate surface, and more particularly, to a method used when forming a seed layer made of Co in a Cu wiring structure.
半導体デバイスの配線構造の１つとしてＣｕ配線構造があり、このようなＣｕ配線構造では、層間絶縁膜に形成したホールやトレンチ内に電解メッキ法によりＣｕ配線層が埋め込み形成される。Ｃｕ配線層を形成するのに際しては、ホールやトレンチに、層間絶縁膜へのＣｕの拡散防止膜として機能するバリア層と、電解メッキ時に電極として機能するシード層とが通常設けられる。ここで、シード層としては、半導体デバイスの速度と機能が改良されるのにつれて、例えばモフォロジーが良好で、且つ、Ｔｉ、ＴｉＮ等からなるバリア層との密着性が良好であり、その上、シード層自体が更に低抵抗であることが求められ、このようなシード層としてＣｏ膜が有望視されている。 One of the wiring structures of semiconductor devices is a Cu wiring structure. In such a Cu wiring structure, a Cu wiring layer is embedded in a hole or trench formed in an interlayer insulating film by electrolytic plating. When forming the Cu wiring layer, a barrier layer that functions as an anti-diffusion film for Cu to the interlayer insulating film and a seed layer that functions as an electrode during electrolytic plating are usually provided in the holes and trenches. As the seed layer, as the speed and function of the semiconductor device are improved, for example, the morphology is good and the adhesiveness with the barrier layer made of Ti, TiN, etc. is good. The layer itself is required to have a lower resistance, and a Co film is promising as such a seed layer.
Ｃｏ膜形成方法として、例えば、コバルトにアミド基、アルキル基、フェニル基、ペンタジエニル基またはカルボニル基などが配位したものを有機金属材料とし、この有機金属材料を気化させて原料ガスを生成し、この原料ガスの雰囲気に基材表面を暴露してＣｏ膜を形成することが知られている（特許文献１参照）。特許文献１記載の方法では、有機金属材料の化学反応によりＣｏ膜を形成するため、炭素等の分解物の生成が避けられない。 As a Co film forming method, for example, an amide group, an alkyl group, a phenyl group, a pentadienyl group or a carbonyl group coordinated to cobalt is used as an organometallic material, and the organometallic material is vaporized to generate a raw material gas. It is known that a Co film is formed by exposing the substrate surface to the atmosphere of the source gas (see Patent Document 1). In the method described in Patent Document 1, since a Co film is formed by a chemical reaction of an organometallic material, generation of decomposition products such as carbon is inevitable.
このため、特許文献１記載の方法では、Ｃｏ膜の成膜後に、赤外線ランプ炉やレーザー光を用いて、Ｃｏ膜をアニールすることが提案されている。然し、赤外線ランプ炉やレーザー光を用いたアニールでは、Ｃｏ膜中に含まれる炭素や窒素といった不純物が効果的に除去されず、また、Ｃｏ膜表面にも炭素などの不純物が残る。結果として、Ｃｏ膜自体の低抵抗化やバリア層及び／またはＣｕ配線層との密着性の向上を効果的に図ることができず、ひいては、Ｃｕ配線自体の低抵抗化を図るのには十分なものではなかった。 For this reason, in the method described in Patent Document 1, it is proposed to anneal the Co film by using an infrared lamp furnace or laser light after the Co film is formed. However, in annealing using an infrared lamp furnace or laser light, impurities such as carbon and nitrogen contained in the Co film are not effectively removed, and impurities such as carbon remain on the Co film surface. As a result, it is not possible to effectively reduce the resistance of the Co film itself and to improve the adhesion with the barrier layer and / or the Cu wiring layer, and as a result, sufficient to reduce the resistance of the Cu wiring itself. It was not something.
本発明は、以上の点に鑑み、膜中及び膜表面の不純物が効果的に除去でき、Ｃｕ配線構造に適用したときにバリア層及びＣｕ配線層に対する密着性に優れて一層の低抵抗を実現できるＣｏ膜形成方法を提供することをその課題とするものである。 In view of the above points, the present invention can effectively remove impurities on the film surface and on the film surface, and when applied to a Cu wiring structure, has excellent adhesion to the barrier layer and the Cu wiring layer and realizes further low resistance. It is an object of the present invention to provide a method for forming a Co film.
上記課題を解決するために、本発明は、基材表面にＣｏ膜を形成するＣｏ膜形成方法であって、基材を処理室内に配置してこの処理室内を真空引きすると共に、この基材を一の所定温度に加熱し、アルキル基を有するイオン又は分子がコバルトに配位した有機金属材料を気化させ、気化させた有機金属材料を基材表面に供給し、有機金属材料を熱分解させてＣｏ膜を成膜する成膜工程と、同一の処理室内で、または前記Ｃｏ膜が成膜された基材を他の処理室内に配置し、この基材をアンモニアガスと水素ガスとを含む混合ガス雰囲気中にて他の所定温度でアニールするアニール工程と、を含むことを特徴とする。 In order to solve the above problems, the present invention provides a Co film forming method for forming a Co film on a surface of a base material, the base material being arranged in a processing chamber and evacuating the processing chamber. Is heated to a predetermined temperature to vaporize an organometallic material in which ions or molecules having an alkyl group are coordinated to cobalt, supply the vaporized organometallic material to the substrate surface, and thermally decompose the organometallic material. The Co film is formed in the same process chamber or the substrate on which the Co film is formed is disposed in another process chamber, and the substrate contains ammonia gas and hydrogen gas. And an annealing step of annealing at another predetermined temperature in a mixed gas atmosphere.
本発明によれば、成膜工程において、アルキル基を有するイオン又は分子がコバルトに配位した、酸素を含まない有機金属材料を用いるため、成膜後のＣｏ膜中の酸素含有量を可能な限り少なくできる。ここで、Ｃｏを配位させる材料として、上記従来の如く、ペンタジエニルまたはカルボニル等を用いると、これらの材料は酸素を含むものであるため、成膜後のＣｏ膜中には酸素が多く含まれ、アニールしても酸素を確実に除去できない場合がある。このような状態で、その後工程にてＣｕ配線層を電解メッキにより形成すると、Ｃｏ膜がメッキ液に溶解してしまう。それに対して、本発明では、酸素を含まない有機金属材料を用いるため、このような不具合が生じ難い。 According to the present invention, since an organic metal material containing no oxygen in which ions or molecules having an alkyl group are coordinated to cobalt is used in the film formation step, the oxygen content in the Co film after film formation is possible. As little as possible. Here, as materials for coordinating Co, when pentadienyl, carbonyl, or the like is used as in the conventional case, these materials contain oxygen. Therefore, the Co film after film formation contains a large amount of oxygen, and annealing is performed. Even in this case, oxygen may not be removed reliably. In such a state, if the Cu wiring layer is formed by electrolytic plating in the subsequent process, the Co film is dissolved in the plating solution. On the other hand, in the present invention, since an organic metal material not containing oxygen is used, such a problem hardly occurs.
そして、成膜工程にてＣｏ膜が形成された基材を、アンモニアガスと水素ガスとを含む混合ガス雰囲気、言い換えると、還元ガス雰囲気にてアニールするようにしたため、成膜されたＣｏ膜中の炭素や窒素といった不純物が効果的に除去され、Ｃｏ膜自体を低抵抗化でき、その上、Ｃｏ膜表面での炭素の濃度を低くすることができる。このため、本発明のＣｏ膜形成方法をＣｕ配線構造におけるシード層の形成に適用すれば、Ｃｏ膜たるシード層とバリア層との密着性を向上できると共に、Ｃｏ膜たるシード層とＣｕ配線層との密着性も向上し、結果として、Ｃｏ膜を低抵抗化できることと相俟って、Ｃｕ配線の一層の低抵抗化が実現できる。 In addition, since the substrate on which the Co film is formed in the film forming process is annealed in a mixed gas atmosphere containing ammonia gas and hydrogen gas, in other words, in a reducing gas atmosphere, in the formed Co film The impurities such as carbon and nitrogen are effectively removed, the resistance of the Co film itself can be reduced, and the concentration of carbon on the surface of the Co film can be lowered. Therefore, if the Co film formation method of the present invention is applied to the formation of a seed layer in a Cu wiring structure, the adhesion between the seed layer as a Co film and the barrier layer can be improved, and the seed layer as a Co film and the Cu wiring layer can be improved. As a result, coupled with the fact that the resistance of the Co film can be reduced, the resistance of the Cu wiring can be further reduced.
なお、本発明において、基材とは、Ｃｏ膜が形成される、シリコンウエハのような半導体基板、セラミックスや樹脂等からなる基板等の成膜対象物をいい、また、例えば基板表面に形成された層間絶縁膜にトレンチ又はホールが形成され、トレンチ又はホール内にＴｉ、Ｔａ、ＴｉＮやＴａＮなどのバリア層が形成されたものを含む。 In the present invention, the base material refers to a film formation target such as a semiconductor substrate such as a silicon wafer, a substrate made of ceramics, resin, or the like on which a Co film is formed. In addition, a trench or hole is formed in the interlayer insulating film, and a barrier layer such as Ti, Ta, TiN, or TaN is formed in the trench or hole.
本発明においては、他の所定温度を一の所定温度よりも高くすることが好ましい。このようにアニール時の他の所定温度を、成膜時の一の所定温度よりも高くすることで、短時間で効果的にＣｏ膜中の不純物を除去できる。この場合、他の所定温度は、２５０℃〜３５０℃の範囲に設定すればよい。２５０℃より低いと、Ｃｏ膜中の不純物を十分に除去できないため、低抵抗のＣｏ膜が得られない。また、半導体デバイスの構造上、半導体デバイスの配線工程では３５０℃より高い温度を使用できない。 In the present invention, it is preferable that the other predetermined temperature is higher than one predetermined temperature. As described above, by making the other predetermined temperature during annealing higher than the one predetermined temperature during film formation, impurities in the Co film can be effectively removed in a short time. In this case, what is necessary is just to set other predetermined temperature in the range of 250 to 350 degreeC. If the temperature is lower than 250 ° C., impurities in the Co film cannot be sufficiently removed, so that a low resistance Co film cannot be obtained. Further, due to the structure of the semiconductor device, a temperature higher than 350 ° C. cannot be used in the wiring process of the semiconductor device.
ところで、アニール工程において、アンモニアガスまたは水素ガスのいずれか一方のみを含むガス雰囲気中にてアニールを行い得るが、アンモニアのみを含む場合には、Ｃｏ膜中及びＣｏ膜表面の窒素が効果的に除去されない一方で、水素ガスのみを含む場合には、Ｃｏ膜中及びＣｏ膜表面の炭素が効果的に除去されない。このため、アニールは、アンモニア及び水素ガスの両者を含むガス雰囲気で行う必要があり、この場合において、アニール工程における水素ガスの分圧を、１〜１０００Ｐａとすることが好ましく、１００Ｐａ〜１０００Ｐａとすることがより好ましい。水素ガスの分圧がこれ以外の範囲では、不純物を十分に除去できないという不具合が生じる。 By the way, in the annealing step, annealing can be performed in a gas atmosphere containing only one of ammonia gas and hydrogen gas. However, when only ammonia is contained, nitrogen in the Co film and the Co film surface is effectively used. On the other hand, when only hydrogen gas is contained, carbon in the Co film and on the Co film surface is not effectively removed. For this reason, annealing needs to be performed in a gas atmosphere containing both ammonia and hydrogen gas. In this case, the partial pressure of hydrogen gas in the annealing step is preferably 1 to 1000 Pa, and is preferably 100 Pa to 1000 Pa. It is more preferable. When the partial pressure of the hydrogen gas is in a range other than this, there arises a problem that impurities cannot be removed sufficiently.
以下、図面を参照して、基材Ｓを、ウエハ１表面にＳｉＯ２等の絶縁膜２を所定膜厚で形成した後、絶縁膜２中にコンタクトホール３をパター二ング形成し、コンタクトホール３を含む絶縁膜２表面にＴＩＷ等からなるバリア層４が形成されたものとし（図１参照）、このバリア層４表面にＣｏからなるシード層５を形成する場合を例に本発明の実施形態のＣｏ膜形成方法を説明する。なお、図１中、６は、シード層５を電極とする電解めっき法により形成されるＣｕ配線層である。 Hereinafter, with reference to the drawings, a substrate S, after forming an insulating film 2 of SiO 2 or the like at a predetermined thickness on the wafer 1 surface, the contact hole 3 and putter-learning formed in the insulating film 2, a contact hole The barrier layer 4 made of TIW or the like is formed on the surface of the insulating film 2 containing 3 (see FIG. 1), and the seed layer 5 made of Co is formed on the surface of the barrier layer 4 as an example. The Co film forming method of the embodiment will be described. In FIG. 1, 6 is a Cu wiring layer formed by electrolytic plating using the seed layer 5 as an electrode.
シード層５を形成する本実施形態のＣｏ膜形成方法は、成膜工程とアニール工程とを含む。即ち、基材Ｓを処理室内に配置し、この処理室内を真空引きすると共に、この基材を一の所定温度に加熱し、アルキル基を有するイオン又は分子がＣｏに配位した有機金属材料を気化させ、気化させた有機金属材料を基材表面に供給する。そして、有機金属材料を熱分解させてＣｏ膜を成膜する（成膜工程）。このとき、水素ガスやアンモニアガスを導入して、還元雰囲気中でＣｏ膜を成膜することもできる。次に、同一の処理室内にて、基材Ｓをアンモニアガスと水素ガスとを含む混合ガス雰囲気中にて他の所定温度でアニールする（アニール工程）。以下に、図２を参照して、成膜工程とアニール工程とを実施し得る真空処理装置を説明する。 The Co film forming method of the present embodiment for forming the seed layer 5 includes a film forming process and an annealing process. That is, the base material S is disposed in the processing chamber, the processing chamber is evacuated, the base material is heated to a predetermined temperature, and an organometallic material in which ions or molecules having an alkyl group are coordinated to Co is obtained. Vaporized and vaporized organometallic material is supplied to the substrate surface. Then, the organometallic material is thermally decomposed to form a Co film (deposition process). At this time, a Co film can be formed in a reducing atmosphere by introducing hydrogen gas or ammonia gas. Next, the substrate S is annealed at another predetermined temperature in a mixed gas atmosphere containing ammonia gas and hydrogen gas in the same processing chamber (annealing step). Hereinafter, a vacuum processing apparatus capable of performing the film forming process and the annealing process will be described with reference to FIG.
図２に示すように、真空処理装置Ｍは、処理室１０たる真空チャンバを備え、処理室１０の底部には、排気管１１を介して真空ポンプ（例えば、ターボ分子ポンプやロータリポンプ等）が接続されている。処理室１０内には、基材Ｓを載置するステージ１２が設けられている。ステージ１２にはヒータ１３が内蔵され、基材Ｓを所定温度に加熱できるようになっている。 As shown in FIG. 2, the vacuum processing apparatus M includes a vacuum chamber serving as a processing chamber 10, and a vacuum pump (for example, a turbo molecular pump or a rotary pump) is provided at the bottom of the processing chamber 10 via an exhaust pipe 11. It is connected. A stage 12 on which the substrate S is placed is provided in the processing chamber 10. The stage 12 includes a heater 13 so that the substrate S can be heated to a predetermined temperature.
処理室１０の上部には、ステージ１２に対向させて混合室１４が配置されている。混合室１４は、半球状の仕切板により画成され、その内部には、気化させた原料金属材料Ｌを供給する第１の供給管１５と、水素ガス、アンモニアガス及びアルゴンガスを夫々供給する第２の供給管１６とが突設されている。 A mixing chamber 14 is disposed on the upper portion of the processing chamber 10 so as to face the stage 12. The mixing chamber 14 is defined by a hemispherical partition plate, and a first supply pipe 15 for supplying the vaporized raw metal material L, and hydrogen gas, ammonia gas, and argon gas are supplied to the inside thereof, respectively. A second supply pipe 16 is projected.
第１の供給管１５は、原料容器１５ａに連通している。原料容器１５ａには、液体の有機金属材料Ｌが貯留されており、図外のヒータにより所定温度（例えば７０℃）に加熱されるようになっている。ここで、有機金属材料Ｌとしては、アルキル基を有するイオン又は分子がＣｏに配位したもの、例えば、ビス（ｔブチル−エチル−エチルアミジナート）コバルトのようなコバルトアルキルアミジナートや、酸素を含まないＣｏ（ＣＨ３Ｃ５Ｈ４）２｛ビス（メチルシクロペンタジエニル）コバルト｝等を用いることができる。また、有機金属材料Ｌとしては、アミド基を有するイオン又は分子がＣｏに配位したものも用いることができる。なお、固体の有機金属材料を溶媒に溶かしたものを原料容器１５ａに貯留することもできる。また、原料容器１５ａの内部には、マスフローコントローラ１５ｂが介設され、アルゴンガス等のキャリアガスを導入する気体導入管１５ｃが突設され、原料容器１５ａ内にキャリアガスを導入することにより、バブリング作用で有機金属材料Ｌを気化させることができる。 The first supply pipe 15 communicates with the raw material container 15a. A liquid organometallic material L is stored in the raw material container 15a and is heated to a predetermined temperature (for example, 70 ° C.) by a heater (not shown). Here, as the organometallic material L, an alkyl group-containing ion or molecule is coordinated to Co, for example, a cobalt alkylamidinate such as bis (tbutyl-ethyl-ethylamidinato) cobalt, Co (CH 3 C 5 H 4 ) 2 {bis (methylcyclopentadienyl) cobalt} or the like that does not contain oxygen can be used. Further, as the organometallic material L, a material in which an ion or molecule having an amide group is coordinated to Co can also be used. In addition, what melt | dissolved the solid organometallic material in the solvent can also be stored in the raw material container 15a. In addition, a mass flow controller 15b is provided inside the raw material container 15a, and a gas introduction pipe 15c for introducing a carrier gas such as argon gas protrudes from the raw material container 15a. The organometallic material L can be vaporized by the action.
他方、第２の供給管１６は複数に分岐されて、各分岐管１６１、１６２、１６３には、マスフローコントローラ１６１ａ、１６２ａ、１６３ａが介設されて水素ガス、アンモニアガス及びアルゴンガスの各ガス源に連通している。処理室１０内の混合室１４とステージ１２との間には、複数の貫通孔１７ａが等間隔で形成されたシャワープレート１７が配置され、混合室１４の噴出孔１４ａから流出したガスが、シャワープレート１７を介して基材Ｓ表面に均一に供給されるようになっている。 On the other hand, the second supply pipe 16 is branched into a plurality of parts, and mass flow controllers 161a, 162a, and 163a are interposed in the branch pipes 161, 162, and 163, respectively, and gas sources of hydrogen gas, ammonia gas, and argon gas are provided. Communicating with Between the mixing chamber 14 in the processing chamber 10 and the stage 12, a shower plate 17 having a plurality of through-holes 17a formed at equal intervals is arranged, and the gas flowing out from the ejection holes 14a of the mixing chamber 14 flows into the shower. It is supplied uniformly to the surface of the substrate S via the plate 17.
次に、上記真空処理装置ＭによるＣｏ膜の形成について具体的に説明する。上記基材Ｓを処理室１０内のステージ１２上に載置した後、図示省略の真空ポンプにより処理室１０内を真空引きすると共に、ヒータ１３を用いて基材Ｓの加熱を開始する（なお、所定圧力に真空引きした処理室１０内に基材を搬送するようにしてもよい）。ここで、基材Ｓは、有機金属材料Ｌに応じて、その熱分解温度よりも高い１８０℃〜３５０℃の範囲の一の所定温度に加熱、保持される。３５０℃より高い温度に加熱すると、Ｃｏ原料たる有機金属材料が自己分解するため、Ｃｏ膜中の炭素の量が増大し（炭素濃度が高くなり）、高抵抗なＣｏ膜が形成されるという不具合が生じる。 Next, the formation of the Co film by the vacuum processing apparatus M will be specifically described. After placing the base material S on the stage 12 in the processing chamber 10, the processing chamber 10 is evacuated by a vacuum pump (not shown) and heating of the base material S is started using the heater 13 (note that The substrate may be transported into the processing chamber 10 evacuated to a predetermined pressure). Here, the base material S is heated and held at a predetermined temperature in the range of 180 ° C. to 350 ° C., which is higher than the thermal decomposition temperature, according to the organometallic material L. When heated to a temperature higher than 350 ° C., the organometallic material that is a Co raw material is self-decomposed, so the amount of carbon in the Co film increases (the carbon concentration increases), and a high-resistance Co film is formed. Occurs.
基材Ｓの温度が所定温度（例えば２００℃）に達すると、気体導入管１５ｃから原料容器１５ａ内にアルゴンガスを導入し、バブリング作用にて有機金属材料Ｌを気化させ、気化させた有機金属材料Ｌを混合室１４内に導入する。このとき、キャリアガスたるアルゴンガスは、マスフローコントローラ１５ｂにより１０ｓｃｃｍ〜１０００ｓｃｃｍの流量に制御される。１０ｓｃｃｍより流量が少ないと、十分なＣｏ原料を供給することができない。また、１０００ｓｃｃｍより流量が多くなると、Ｃｏ原料の濃度がアルゴンガスにより希釈され、十分な原料分圧が確保できないという不具合が生じる。そして、混合室１４に導入された有機金属材料Ｌが当該混合室１４にて拡散された後、噴出孔１４ａから噴出されてシャワープレート１７を介して基材Ｓ表面に供給される。これにより、一の所定温度に保持された基材Ｓ表面に達した有機金属材料Ｌが熱分解してＣｏ膜が成膜される。尚、混合室１４内に水素ガスやアンモニアガスを導入して、還元雰囲気中で成膜することもできる。Ｃｏ膜の成膜終了後、気化した有機金属材料Ｌの供給を停止し、処理室１０内を所定圧力（１００Ｐａ）まで一旦排気する。 When the temperature of the base material S reaches a predetermined temperature (for example, 200 ° C.), argon gas is introduced into the raw material container 15a from the gas introduction pipe 15c, and the organic metal material L is vaporized by a bubbling action. The material L is introduced into the mixing chamber 14. At this time, the argon gas as the carrier gas is controlled to a flow rate of 10 sccm to 1000 sccm by the mass flow controller 15b. If the flow rate is less than 10 sccm, sufficient Co raw material cannot be supplied. Further, when the flow rate is higher than 1000 sccm, the concentration of the Co raw material is diluted with argon gas, which causes a problem that sufficient raw material partial pressure cannot be secured. Then, after the organometallic material L introduced into the mixing chamber 14 is diffused in the mixing chamber 14, it is ejected from the ejection holes 14 a and supplied to the surface of the substrate S through the shower plate 17. As a result, the organometallic material L reaching the surface of the substrate S held at one predetermined temperature is thermally decomposed to form a Co film. It is also possible to form a film in a reducing atmosphere by introducing hydrogen gas or ammonia gas into the mixing chamber 14. After the Co film is formed, the supply of the vaporized organometallic material L is stopped, and the inside of the processing chamber 10 is temporarily evacuated to a predetermined pressure (100 Pa).
次に、Ｃｏ膜が形成された基材Ｓを、成膜時の基材温度よりも高い２５０℃〜３５０℃の範囲の他の所定温度まで昇温させて保持する。これと同時に、処理室１０内に水素ガスとアンモニアガスを導入して還元雰囲気を形成し、この還元雰囲気にてＣｏ膜をアニールする。このように、アニール時の温度（他の所定温度）を、成膜時の基材Ｓ温度（一の所定温度）よりも高くすると、短い処理時間で効果的にＣｏ膜の抵抗値を低くできるものの、３５０℃を超える温度のアニールは半導体デバイスの配線工程には使用できない。また、水素ガスとアンモニアガスの流量は、マスフローコントローラ１６１ａ、１６２ａにより１０〜１０００ｓｃｃｍ、１０〜１０００ｓｃｃｍに制御する。 Next, the base material S on which the Co film is formed is heated up to another predetermined temperature in the range of 250 ° C. to 350 ° C. higher than the base material temperature at the time of film formation and held. At the same time, hydrogen gas and ammonia gas are introduced into the processing chamber 10 to form a reducing atmosphere, and the Co film is annealed in this reducing atmosphere. As described above, when the annealing temperature (other predetermined temperature) is higher than the substrate S temperature (one predetermined temperature) during film formation, the resistance value of the Co film can be effectively reduced in a short processing time. However, annealing at a temperature exceeding 350 ° C. cannot be used in the wiring process of semiconductor devices. The flow rates of hydrogen gas and ammonia gas are controlled to 10 to 1000 sccm and 10 to 1000 sccm by the mass flow controllers 161a and 162a.
上記実施形態によれば、成膜工程において、有機金属材料Ｌとして、アルキル基を有するイオン又は分子がコバルトに配位した、酸素を含まないものを用いるため、成膜後のＣｏ膜中の酸素含有量を可能な限り少なくできる。このため、アニール後にＣｏ膜表面に酸素が残り、後工程の電解メッキによるＣｕ配線層形成時にＣｏ膜がメッキ液に溶解することが防止できる。そして、アニール工程時に、水素ガスとアンモニアガスとを含む還元混合ガス雰囲気にてアニールするため、Ｃｏ膜中の炭素や窒素等の不純物が効果的に除去され、Ｃｏ膜を低抵抗化でき、その上、Ｃｏ膜表面での炭素のような不純物の濃度を低くすることができる。このため、シード層５とバリア層４との密着性を向上できると共に、Ｃｕ配線層６とシード層５との密着性も向上できる。そして、Ｃｕ配線の一層の低抵抗化が実現できる。 According to the above-described embodiment, in the film formation step, the organic metal material L uses an oxygen-free material in which ions or molecules having an alkyl group are coordinated to cobalt, so that oxygen in the Co film after film formation is used. The content can be reduced as much as possible. For this reason, oxygen remains on the surface of the Co film after annealing, and it is possible to prevent the Co film from being dissolved in the plating solution when a Cu wiring layer is formed by electrolytic plating in a later step. And, since annealing is performed in a reducing mixed gas atmosphere containing hydrogen gas and ammonia gas during the annealing process, impurities such as carbon and nitrogen in the Co film are effectively removed, and the resistance of the Co film can be reduced. In addition, the concentration of impurities such as carbon on the Co film surface can be lowered. For this reason, the adhesion between the seed layer 5 and the barrier layer 4 can be improved, and the adhesion between the Cu wiring layer 6 and the seed layer 5 can also be improved. And further resistance reduction of Cu wiring is realizable.
次に、上記効果を確認するために上記装置Ｍを用いた下記の実験（実験１）を行った。基材Ｓとして、φ３００ｍｍのシリコンウエハ１上にＳｉＯ２膜２が１００ｎｍの膜厚で形成されたものを用いた。そして、基材Ｓ表面に上記実施形態に従いＣｏ膜５を形成した。 Next, in order to confirm the above effect, the following experiment (Experiment 1) using the apparatus M was performed. As the substrate S, a substrate in which a SiO 2 film 2 was formed to a thickness of 100 nm on a silicon wafer 1 having a diameter of 300 mm was used. Then, the Co film 5 was formed on the surface of the substrate S according to the above embodiment.
成膜工程において、有機金属材料Ｌとしてアルキルアミジナートを用い、原料容器１５ａ内にキャリアガスを流量３００ｓｃｃｍで導入することにより気化させたアルキルアミジナートを混合室１４に導入し、また、基材Ｓの加熱温度を２００℃、処理時間を１５分に設定した。次に、アニール工程において、基材Ｓの加熱温度を３００℃または３５０℃に設定すると共に、水素ガス及びアンモニアガスを所定の流量比で混合室１４に導入し、処理時間を２分に設定してＣｏ膜５をアニールした。 In the film forming process, an alkylamidinate is used as the organometallic material L, and the alkylamidinate vaporized by introducing a carrier gas into the raw material container 15a at a flow rate of 300 sccm is introduced into the mixing chamber 14. The heating temperature of the material S was set to 200 ° C., and the treatment time was set to 15 minutes. Next, in the annealing step, the heating temperature of the substrate S is set to 300 ° C. or 350 ° C., hydrogen gas and ammonia gas are introduced into the mixing chamber 14 at a predetermined flow rate ratio, and the processing time is set to 2 minutes. The Co film 5 was annealed.
図３（ａ）は、水素ガス及びアンモニアガスの流量を１００ｓｃｃｍ、１００ｓｃｃｍに夫々設定して水素ガスの流量比（水素ガス／水素ガス＋アンモニアガス）を１とし（このとき、水素ガスの分圧は、２５０Ｐａである）、Ｃｏ膜５が形成された基材Ｓのアニール時の処理温度（他の所定温度）を変えたときのＣｏ膜のシート抵抗の変化を示すグラフである。これによれば、アニール時の加熱温度が高い程、短い時間で効果的にＣｏ膜５のシート抵抗を下げることができたことが判る。また、図３（ｂ）は、Ｃｏ膜５が形成された基材Ｓの処理温度を３００℃とし、水素ガスの流量比（水素ガス／水素ガス＋アンモニアガス）を変化させたときのＣｏ膜５のシート抵抗割合を示すグラフである。ここで、Ｃｏ膜５のシート抵抗割合とは、成膜後のＣｏ膜５のシート抵抗に対するアニール後のＣｏ膜５のシート抵抗の割合をいう。これによれば、水素ガスの流量比が０．５（水素ガスの分圧２５０Ｐａ）のとき効果的にＣｏ膜５のシート抵抗割合を下げることができたことが判る。 FIG. 3A shows that the flow rates of hydrogen gas and ammonia gas are set to 100 sccm and 100 sccm, respectively, and the flow rate ratio of hydrogen gas (hydrogen gas / hydrogen gas + ammonia gas) is set to 1 (at this time, the partial pressure of hydrogen gas) Is a graph showing changes in sheet resistance of the Co film when the processing temperature (other predetermined temperature) during annealing of the substrate S on which the Co film 5 is formed is changed. According to this, it can be seen that the higher the heating temperature during annealing, the lower the sheet resistance of the Co film 5 can be effectively reduced in a shorter time. FIG. 3B shows the Co film when the processing temperature of the substrate S on which the Co film 5 is formed is 300 ° C. and the flow rate ratio of hydrogen gas (hydrogen gas / hydrogen gas + ammonia gas) is changed. 5 is a graph showing a sheet resistance ratio of 5. Here, the sheet resistance ratio of the Co film 5 refers to the ratio of the sheet resistance of the Co film 5 after annealing to the sheet resistance of the Co film 5 after film formation. According to this, it can be seen that the sheet resistance ratio of the Co film 5 can be effectively reduced when the flow rate ratio of hydrogen gas is 0.5 (hydrogen gas partial pressure 250 Pa).
次に、上記装置Ｍを用いて他の実験（実験２）を行った。本実験では、基材Ｓとして上記と同一のものを用いた。また、成膜工程では、上記と同一条件でＣｏ膜５を形成した。次に、所定条件でアニール工程を行った後、ｐＨ１以下の強酸性下で電解メッキ法によりＣｏ膜５上にＣｕ配線層６を例えば５ｎｍ堆積した。 Next, another experiment (Experiment 2) was performed using the apparatus M. In this experiment, the same substrate as that described above was used. In the film forming process, the Co film 5 was formed under the same conditions as described above. Next, after performing an annealing process under a predetermined condition, a Cu wiring layer 6 having a thickness of, for example, 5 nm was deposited on the Co film 5 by electrolytic plating under a strong acidity of pH 1 or less.
図４（ａ）は、上記実験１と同様、本実施形態に従い、アニール工程において、Ｃｏ膜５が形成された基材Ｓの処理温度を３００℃とし、水素ガスの流量比（水素ガス／水素ガス＋アンモニアガス）を０．５に設定した場合のオージェ電子分光法（ＡＥＳ：Auger Electron Spectroscopy）による分析結果である。 FIG. 4A shows a hydrogen gas flow rate ratio (hydrogen gas / hydrogen) in the annealing step with the processing temperature of the substrate S on which the Co film 5 is formed being 300 ° C., as in Experiment 1 above, in the same manner as in Experiment 1 above. It is an analysis result by Auger Electron Spectroscopy (AES) when (gas + ammonia gas) is set to 0.5.
比較実験として、アニール工程時に水素ガスのみを５００ｓｃｃｍの流量で導入し（比較実験１）、アニール工程を経ることなく、Ｃｏ膜５の形成直後にＣｕ配線層６を形成し（比較実験２）、アニール工程時にアンモニアガスのみを５００ｓｃｃｍの流量で導入し（比較実験３）、オージェ電子分光法による分析を行った。図４（ｂ）乃至（ｄ）は、これらの比較実験１乃至３の結果を示すものである。 As a comparative experiment, only hydrogen gas was introduced at a flow rate of 500 sccm during the annealing process (Comparative Experiment 1), and the Cu wiring layer 6 was formed immediately after the formation of the Co film 5 without going through the annealing process (Comparative Experiment 2). During the annealing process, only ammonia gas was introduced at a flow rate of 500 sccm (Comparative Experiment 3), and analysis by Auger electron spectroscopy was performed. 4 (b) to 4 (d) show the results of these comparative experiments 1 to 3. FIG.
以上の実験から、比較実験１では、Ｃｏ膜５中の不純物濃度が少ないが、Ｃｏ膜５とＣｕ配線層６との界面に高濃度の炭素が存在し、効果的に除去できていないことが判る（図４（ｂ）中の丸印参照）。比較実験２では、Ｃｏ膜５中やＣｏ膜５とＣｕ配線層６との界面に炭素や窒素などの不純物が存在し、効果的に除去できていないことが判る。また、比較実験３では、Ｃｏ膜５中及びＣｏ膜５とＣｕ配線層６との界面に比較的高濃度の窒素が存在することが判る。それに対して、実験２では、Ｃｏ膜５中の炭素と窒素の濃度が共に少なく、効果的に除去できており、しかも、Ｃｏ膜５とＣｕ配線層６の界面における炭素の濃度を低くできることが判る。従って、Ｃｏ膜５を低抵抗化できると共に、図５に示すようにＣｏ膜５とＣｕ配線層６との界面において良好な密着性が得られることが判った。 From the above experiments, in Comparative Experiment 1, the impurity concentration in the Co film 5 is low, but high concentration of carbon exists at the interface between the Co film 5 and the Cu wiring layer 6 and cannot be effectively removed. It can be seen (see the circle in FIG. 4B). In Comparative Experiment 2, it can be seen that impurities such as carbon and nitrogen exist in the Co film 5 and at the interface between the Co film 5 and the Cu wiring layer 6 and cannot be effectively removed. In Comparative Experiment 3, it can be seen that a relatively high concentration of nitrogen exists in the Co film 5 and at the interface between the Co film 5 and the Cu wiring layer 6. On the other hand, in Experiment 2, the concentrations of carbon and nitrogen in the Co film 5 are both low and can be effectively removed, and the carbon concentration at the interface between the Co film 5 and the Cu wiring layer 6 can be lowered. I understand. Therefore, it has been found that the resistance of the Co film 5 can be reduced and good adhesion can be obtained at the interface between the Co film 5 and the Cu wiring layer 6 as shown in FIG.
以上、本発明の実施形態について説明したが、本発明は、上記実施形態に限定されるものではない。上記実施形態では、有機金属気相成長法（ＭＯＣＶＤ法）によりＣｏ膜を成膜しているが、Ｃｏ膜の成膜方法はこれに限られず、原子層堆積法（ＡＬＤ法）によりＣｏ膜を成膜してもよい。例えば、処理室１０内の圧力を２００Ｐａとし、基材Ｓを２００℃に加熱する。そして、処理室１０内に３００ｓｃｃｍのキャリアガスを用いてコバルトメチルアミジナートを２ｓｅｃ導入した後、アルゴンガスを２００ｓｃｃｍで２ｓｅｃ導入し、その後排気する。続いて、処理室１０内にアンモニアガスと水素ガスとをそれぞれ３００ｓｃｃｍ、３００ｓｃｃｍで２ｓｅｃ導入した後、アルゴンガスを２００ｓｃｃｍで２ｓｅｃ導入し、その後排気する。この一連の処理を複数回繰り返すことにより、Ｃｏ膜が形成される。その後、上記実施形態で説明したようにアニールを実行することで、Ｃｏ膜中及びＣｏ膜表面の不純物を効果的に低減することができる。 As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. In the above embodiment, the Co film is formed by the metal organic chemical vapor deposition method (MOCVD method). However, the Co film forming method is not limited to this, and the Co film is formed by the atomic layer deposition method (ALD method). A film may be formed. For example, the pressure in the processing chamber 10 is set to 200 Pa, and the substrate S is heated to 200 ° C. Then, after introducing cobalt methyl amidinate into the processing chamber 10 for 2 sec using 300 sccm of carrier gas, argon gas is introduced for 2 sec at 200 sccm, and then exhausted. Subsequently, ammonia gas and hydrogen gas are introduced into the processing chamber 10 at 300 sccm and 300 sccm for 2 sec, respectively, and argon gas is introduced at 200 sccm for 2 sec and then exhausted. By repeating this series of processes a plurality of times, a Co film is formed. Thereafter, annealing is performed as described in the above embodiment, so that impurities in the Co film and the Co film surface can be effectively reduced.
また、上記実施形態では、Ｃｏ膜の成膜とアニールとを同一の処理室にて行う場合について説明したが、Ｃｏ膜が成膜された基材を他の処理室内に配置してアニールを行うようにしてもよい。 In the above-described embodiment, the case where the Co film is formed and annealed in the same processing chamber has been described. However, the substrate on which the Co film is formed is disposed in another processing chamber and the annealing is performed. You may do it.
また、上記実施形態では、抵抗加熱式のヒータ１３を用いて基材Ｓを加熱する場合について説明したが、他の公知の加熱方式を用いてもよい。 Moreover, although the said embodiment demonstrated the case where the base material S was heated using the resistance heating type heater 13, you may use another well-known heating system.
Ｓ…基材、 １０…処理室、 Ｌ…有機金属材料。 S: base material, 10: processing chamber, L: organometallic material.
Claims (2)
基材を処理室内に配置してこの処理室内を真空引きすると共に、この基材を一の所定温度に加熱し、アルキル基を有するイオン又は分子がコバルトに配位した有機金属材料を気化させ、気化させた有機金属材料を基材表面に供給し、有機金属材料を熱分解させてＣｏ膜を成膜する成膜工程と、
同一の処理室内で、または前記Ｃｏ膜が成膜された基材を他の処理室内に配置し、この基材をアンモニアガスと水素ガスとを含む混合ガス雰囲気中にて他の所定温度でアニールするアニール工程と、を含み、
前記他の所定温度を前記一の所定温度よりも高く且つ３００〜３５０℃に設定し、
アンモニアガスと水素ガスとを含む前記混合ガス雰囲気における水素ガスの流量比を０．５に設定することを特徴とするＣｏ膜形成方法。 A Co film forming method for forming a Co film on a substrate surface,
A substrate is placed in the processing chamber and the processing chamber is evacuated, and the substrate is heated to a predetermined temperature to vaporize an organometallic material in which ions or molecules having an alkyl group are coordinated to cobalt. A film forming step of supplying a vaporized organometallic material to the substrate surface and thermally decomposing the organometallic material to form a Co film;
Place the base material on which the Co film is formed in the same processing chamber or another processing chamber, and anneal this base material in a mixed gas atmosphere containing ammonia gas and hydrogen gas at another predetermined temperature. and the annealing step of, only including,
The other predetermined temperature is set higher than the one predetermined temperature and 300 to 350 ° C.,
A Co film forming method, characterized in that a flow ratio of hydrogen gas in the mixed gas atmosphere containing ammonia gas and hydrogen gas is set to 0.5 .
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