JP2010272571A - Semiconductor device and manufacturing method thereof - Google Patents
Semiconductor device and manufacturing method thereof Download PDFInfo
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Abstract
【課題】配線の埋め込み不良及び配線抵抗の上昇を抑えると共に、信頼性を向上した半導体装置を実現できるようにする。
【解決手段】半導体装置は、基板１０１の上に形成された絶縁膜１０５と、絶縁膜１０５中に形成された、銅を含む材料からなる埋め込み配線１１５とを備えている。絶縁膜１０５と埋め込み配線１１５との間には、白金族元素を含む材料からなるバリア膜１１０が形成されている。絶縁膜１０５とバリア膜１１０との間には、絶縁膜１０５よりも密度が高い高密度絶縁膜１０９が形成されている。
【選択図】図６An object of the present invention is to realize a semiconductor device with improved reliability while suppressing poor wiring embedding and increased wiring resistance.
A semiconductor device includes an insulating film formed on a substrate and a buried wiring made of a material containing copper and formed in the insulating film. A barrier film 110 made of a material containing a platinum group element is formed between the insulating film 105 and the embedded wiring 115. A high-density insulating film 109 having a higher density than the insulating film 105 is formed between the insulating film 105 and the barrier film 110.
[Selection] Figure 6
Description
本発明は、半導体装置及びその製造方法に関し、特に、銅等からなる埋め込み配線を有する半導体装置及びその製造方法に関する。 The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly to a semiconductor device having a buried wiring made of copper or the like and a manufacturing method thereof.
半導体装置に用いる配線は、絶縁膜に形成した凹部に、銅又は銅合金等の材料を埋め込んだいわゆる銅配線が主流となりつつある。銅配線を形成する場合、凹部にバリア膜を形成した後、スパッタ法等を用いてバリア膜の上にシード層を形成し、電界めっき法を用いて凹部に銅等の材料を埋め込む方法が一般的に用いられている。バリア膜は、配線側から絶縁膜側へ銅原子が拡散することを防止し、半導体装置の信頼性を向上させるために形成する。従って、バリア膜は銅原子が拡散しにくい材料を用いて形成する必要がある。しかし、バリア膜に、酸化されやすく且つ酸化されると導電性が大きく低下する材料を用いた場合、電界めっきを行う際にバリア膜が酸化された部分に電流が流れなくなるため、ボイド等の埋め込み不良が発生する。また、バリア膜が酸化された部分は高抵抗となるため、配線抵抗が上昇してしまう。 As a wiring used for a semiconductor device, a so-called copper wiring in which a material such as copper or a copper alloy is embedded in a recess formed in an insulating film is becoming mainstream. When forming a copper wiring, a method is generally used in which a barrier film is formed in a recess, a seed layer is formed on the barrier film using a sputtering method, and a material such as copper is embedded in the recess using an electroplating method. Has been used. The barrier film is formed to prevent copper atoms from diffusing from the wiring side to the insulating film side and improve the reliability of the semiconductor device. Therefore, the barrier film needs to be formed using a material in which copper atoms are difficult to diffuse. However, if the barrier film is made of a material that is easily oxidized and whose conductivity is greatly reduced when oxidized, current does not flow to the oxidized portion of the barrier film during electroplating. Defects occur. In addition, since the portion where the barrier film is oxidized has a high resistance, the wiring resistance increases.
このため、ルテニウム等の酸化されても導電性を失わない金属膜又は導電性を有する金属酸化膜からなるバリア膜を使用する方法が知られている（例えば、特許文献１及び２を参照。）。バリア膜にルテニウム等を用いることにより、バリア膜が酸化されても導電性を失うおそれがないため、埋め込み不良が発生したり、配線抵抗が上昇したりすることを防ぐことができる。 For this reason, a method of using a metal film that does not lose its conductivity even when oxidized, such as ruthenium, or a barrier film made of a metal oxide film having conductivity is known (see, for example, Patent Documents 1 and 2). . By using ruthenium or the like for the barrier film, there is no possibility of losing conductivity even when the barrier film is oxidized, so that it is possible to prevent a defective filling or an increase in wiring resistance.
しかしながら、ルテニウム等の酸化されても導電性を失わない金属又はその酸化物は、バリア性が十分でないという問題を有している。このため、配線側から絶縁膜側への銅の拡散が生じたり、絶縁膜側から配線側への酸素の侵入が生じたりしやすい。従って、半導体装置の信頼性が低下してしまうおそれがある。 However, a metal such as ruthenium that does not lose conductivity even when oxidized or an oxide thereof has a problem that the barrier property is not sufficient. For this reason, copper is likely to diffuse from the wiring side to the insulating film side, or oxygen may easily enter from the insulating film side to the wiring side. Therefore, the reliability of the semiconductor device may be reduced.
本発明は、前記の問題を解決し、配線の埋め込み不良及び配線抵抗の上昇を抑えると共に、信頼性を向上した半導体装置を実現できるようにすることを目的とする。 SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, to suppress a wiring embedding failure and an increase in wiring resistance, and to realize a semiconductor device with improved reliability.
前記の目的を達成するため、本発明は半導体装置を、絶縁膜とバリア膜との間に形成された高密度絶縁膜を備えている構成とする。 In order to achieve the above object, according to the present invention, a semiconductor device includes a high-density insulating film formed between an insulating film and a barrier film.
具体的に、本発明に係る半導体装置は、基板の上に形成された絶縁膜と、絶縁膜中に形成された、銅を含む材料からなる埋め込み配線と、絶縁膜と埋め込み配線との間に形成された、白金族元素を含む材料からなるバリア膜と、絶縁膜とバリア膜との間に形成され、絶縁膜よりも密度が高い高密度絶縁膜とを備えていることを特徴とする。 Specifically, a semiconductor device according to the present invention includes an insulating film formed on a substrate, a buried wiring made of a material containing copper, and formed between the insulating film and the buried wiring. And a barrier film made of a material containing a platinum group element and a high-density insulating film formed between the insulating film and the barrier film and having a higher density than the insulating film.
本発明の半導体装置は、絶縁膜とバリア膜との間に形成され、絶縁膜よりも密度が高い高密度絶縁膜を備えている。高密度絶縁膜は絶縁膜と比べて銅の拡散が生じにくい。このため、バリア膜のバリア性が劣化して銅原子の拡散が生じたとしても、銅原子の拡散を高密度絶縁膜において抑制することができる。一方、バリア膜は、白金族元素を含む材料からなるため配線抵抗の増大を防止できる。また、銅との密着性にも優れているため埋め込み不良が発生しにくい。 The semiconductor device of the present invention includes a high-density insulating film that is formed between the insulating film and the barrier film and has a higher density than the insulating film. The high-density insulating film is less likely to cause copper diffusion than the insulating film. For this reason, even if the barrier property of the barrier film deteriorates and copper atoms diffuse, diffusion of copper atoms can be suppressed in the high-density insulating film. On the other hand, since the barrier film is made of a material containing a platinum group element, an increase in wiring resistance can be prevented. Moreover, since it is excellent in adhesiveness with copper, it is difficult to cause poor embedding.
本発明の半導体装置において、高密度絶縁膜は窒素を含んでいてもよい。この場合において高密度絶縁膜は、絶縁膜との界面側からバリア膜との界面側へ向かって窒素含有量が増大していてもよい。 In the semiconductor device of the present invention, the high-density insulating film may contain nitrogen. In this case, the nitrogen content of the high-density insulating film may increase from the interface side with the insulating film toward the interface side with the barrier film.
本発明の半導体装置において絶縁膜は、比誘電率が３．０以下とすればよい。 In the semiconductor device of the present invention, the insulating film may have a relative dielectric constant of 3.0 or less.
本発明の半導体装置において白金族元素は、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウム又は白金とすればよい。 In the semiconductor device of the present invention, the platinum group element may be ruthenium, rhodium, palladium, osmium, iridium, or platinum.
本発明に係る半導体装置の製造方法は、半導体基板の上に絶縁膜を形成する工程（ａ）と、絶縁膜に凹部を形成する工程（ｂ）と、凹部の側面に絶縁膜と比べて密度が高い高密度絶縁膜を形成する工程（ｃ）と、工程（ｃ）よりも後に、凹部の内面に沿って、白金族元素を含む材料からなるバリア膜を形成する工程（ｄ）と、工程（ｄ）よりも後に、凹部の内面に沿って、銅を含む材料からなる第１の導電膜を順次形成する工程（ｅ）と、第１の導電膜の上に、凹部を埋めるように銅を含む材料からなる第２の導電膜を成長させる工程（ｆ）と、工程（ｆ）よりも後に、第１の導電膜と第２の導電膜とを一体化して埋め込み配線を形成する工程（ｇ）とを備えていることを特徴とする。 The method for manufacturing a semiconductor device according to the present invention includes a step (a) of forming an insulating film on a semiconductor substrate, a step (b) of forming a recess in the insulating film, and a density compared to the insulating film on the side surface of the recess. A step (c) of forming a high-density insulating film having a high thickness, a step (d) of forming a barrier film made of a material containing a platinum group element along the inner surface of the concave portion after the step (c), and a step Step (e) of sequentially forming a first conductive film made of a material containing copper along the inner surface of the concave portion after (d), and copper so as to fill the concave portion on the first conductive film. A step (f) of growing a second conductive film made of a material containing a material, and a step of forming the embedded wiring by integrating the first conductive film and the second conductive film after the step (f) ( and g).
本発明に係る半導体装置の製造方法は、凹部の側面に絶縁膜と比べて密度が高い高密度絶縁膜を形成する工程を備えている。このため、白金族元素を含む材料からなるバリア膜にバリア性が劣化した部分が生じたとしても、銅原子の拡散を高密度絶縁膜により抑えることができる。従って、信頼性に優れた半導体装置を実現することができる。 The method for manufacturing a semiconductor device according to the present invention includes a step of forming a high-density insulating film having a higher density than the insulating film on the side surface of the recess. For this reason, even if a portion having a deteriorated barrier property is generated in the barrier film made of a material containing a platinum group element, diffusion of copper atoms can be suppressed by the high-density insulating film. Therefore, a semiconductor device with excellent reliability can be realized.
本発明の半導体装置の製造方法において、工程（ｃ）では、凹部の側面に窒素を含むプラズマを照射することにより、高密度絶縁膜を形成してもよく、工程（ｃ）及び工程（ｄ）は、窒素又は窒素とアルゴンとの混合ガス雰囲気において、白金族元素を含む材料をスパッタすることにより、高密度絶縁膜を形成すると共に、バリア膜を形成する工程としてもよい。 In the method for manufacturing a semiconductor device of the present invention, in the step (c), a high-density insulating film may be formed by irradiating the side surface of the recess with nitrogen-containing plasma. The steps (c) and (d) May be a step of forming a barrier film while forming a high-density insulating film by sputtering a material containing a platinum group element in a mixed gas atmosphere of nitrogen or nitrogen and argon.
本発明の半導体装置の製造方法において、高密度絶縁膜は、絶縁膜との界面側からバリア膜との界面側に向かって、窒素含有量が増大する構成としてもよい。 In the method for manufacturing a semiconductor device of the present invention, the high-density insulating film may have a structure in which the nitrogen content increases from the interface side with the insulating film toward the interface side with the barrier film.
本発明の半導体装置の製造方法において絶縁膜は、比誘電率が３．０以下であってもよい。 In the method for manufacturing a semiconductor device of the present invention, the insulating film may have a relative dielectric constant of 3.0 or less.
本発明の半導体装置の製造方法において、白金族元素は、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウム又は白金とすればよい。 In the method for manufacturing a semiconductor device of the present invention, the platinum group element may be ruthenium, rhodium, palladium, osmium, iridium, or platinum.
本発明に係る半導体装置及びその製造方法によれば、配線の埋め込み不良及び配線抵抗の上昇を抑えると共に、信頼性を向上した半導体装置を実現できる。 According to the semiconductor device and the method for manufacturing the same according to the present invention, it is possible to realize a semiconductor device with improved reliability while suppressing an embedding failure of wiring and an increase in wiring resistance.
本発明の一実施形態について、図面を参照して説明する。まず、一実施形態に係る半導体装置の製造方法について説明する。図１に示すように、半導体基板１００の上に第１の配線１０３を有する第１の絶縁膜１０１形成する。具体的には、まず、半導体素子（図示せず）が形成された半導体基板１００の上に第１の絶縁膜１０１を形成する。続いて、第１の絶縁膜１０１に溝部を形成し、形成した溝部内に、例えばルテニウム膜からなる第１のバリア膜１０２を介して銅からなる第１の配線１０３を埋め込み、溝部を含む第１の絶縁膜１０１の上面を平坦化する。続いて、第１の配線１０３を形成した第１の絶縁膜１０１の上に、第１のシリコン窒化膜１０４及び第２の絶縁膜１０５を順次堆積した後、第１のシリコン窒化膜１０４及び第２の絶縁膜１０５を選択的に除去して、第１の配線１０３に達するビアホール１０６及び配線用溝１０７を形成する。 An embodiment of the present invention will be described with reference to the drawings. First, a method for manufacturing a semiconductor device according to an embodiment will be described. As shown in FIG. 1, a first insulating film 101 having a first wiring 103 is formed on a semiconductor substrate 100. Specifically, first, a first insulating film 101 is formed on a semiconductor substrate 100 on which a semiconductor element (not shown) is formed. Subsequently, a groove portion is formed in the first insulating film 101, and a first wiring 103 made of copper is embedded in the formed groove portion through a first barrier film 102 made of, for example, a ruthenium film, and a first portion including the groove portion is filled. The upper surface of one insulating film 101 is planarized. Subsequently, a first silicon nitride film 104 and a second insulating film 105 are sequentially deposited on the first insulating film 101 on which the first wiring 103 is formed, and then the first silicon nitride film 104 and the second insulating film 105 are deposited. The second insulating film 105 is selectively removed to form a via hole 106 and a wiring trench 107 reaching the first wiring 103.
プラズマＣＶＤ（Chemical Vapor Deposition:化学的気相成長）法等を用いて第２の絶縁膜１０５を堆積する場合には、４００℃程度の熱処理が必要となる。第１のバリア膜１０２及び第１のシリコン窒化膜１０４は、銅原子の拡散に対するバリア性を有しており、４００℃程度の熱処理の際に、第１の配線１０３を構成する銅原子が第１の絶縁膜１０１及び第２の絶縁膜１０５等の内部に拡散することを防止する役割を果たす。 When the second insulating film 105 is deposited using a plasma CVD (Chemical Vapor Deposition) method or the like, a heat treatment at about 400 ° C. is required. The first barrier film 102 and the first silicon nitride film 104 have a barrier property against the diffusion of copper atoms, and the copper atoms constituting the first wiring 103 are the first in the heat treatment at about 400 ° C. It plays the role of preventing diffusion into the first insulating film 101, the second insulating film 105, and the like.
次に、図２に示すように、窒素ガスプラズマ１０８を第２の絶縁膜１０５に照射する。この処理によりビアホール１０６及び配線用溝１０７の側面に膜厚が１ｎｍ〜５ｎｍ程度の窒素を含有する高密度絶縁膜１０９が形成される。高密度絶縁膜１０９は第２の絶縁膜１０５よりも密度が高い絶縁膜である。プラズマ照射により形成した場合、一般的に高密度絶縁膜１０９に含まれる窒素の量（窒素濃度）は第２の絶縁膜１０５と接する側から表面側（第２のバリア膜１１０と接する側）に向かって次第に高くなる。但し、必ずしも窒素濃度は傾斜している必要はない。 Next, as shown in FIG. 2, the second insulating film 105 is irradiated with nitrogen gas plasma 108. By this treatment, a high-density insulating film 109 containing nitrogen having a thickness of about 1 nm to 5 nm is formed on the side surfaces of the via hole 106 and the wiring groove 107. The high-density insulating film 109 is an insulating film having a higher density than the second insulating film 105. When formed by plasma irradiation, the amount of nitrogen (nitrogen concentration) generally contained in the high-density insulating film 109 is from the side in contact with the second insulating film 105 to the surface side (side in contact with the second barrier film 110). It gets higher gradually. However, the nitrogen concentration is not necessarily inclined.
次に、図３に示すように、例えばスパッタ法により半導体基板１００の上に膜厚が１０ｎｍのルテニウムからなる第２のバリア膜１１０を堆積する。スパッタのターゲットはルテニウムとすればよい。その後、例えばスパッタ法により、第２のバリア膜１１０の上に膜厚が３０ｎｍの銅膜からなるシード層１１１を堆積する。これによりビアホール１０６及び配線用溝１０７のそれぞれの底部及び側面は、第２のバリア膜１１０及びシード層１１１により覆われる。 Next, as shown in FIG. 3, a second barrier film 110 made of ruthenium having a thickness of 10 nm is deposited on the semiconductor substrate 100 by, eg, sputtering. The sputtering target may be ruthenium. Thereafter, a seed layer 111 made of a copper film having a thickness of 30 nm is deposited on the second barrier film 110 by, for example, sputtering. As a result, the bottom and side surfaces of the via hole 106 and the wiring groove 107 are covered with the second barrier film 110 and the seed layer 111.
次に、図４に示すように、電解めっき法によりシード層１１１の上に膜厚が３００ｎｍの銅めっき層１１２を、ビアホール１０６及び配線用溝１０７のそれぞれが埋まるように成長させる。 Next, as shown in FIG. 4, a copper plating layer 112 having a film thickness of 300 nm is grown on the seed layer 111 by electrolytic plating so that each of the via hole 106 and the wiring groove 107 is filled.
次に、半導体基板１００をめっき装置から取り出した後、銅めっき層１１２の結晶粒を成長させるために銅めっき層１１２に対して、１００℃程度の温度で２時間程度の熱処理を行う。これにより、図５に示すように、シード層１１１と銅めっき層１１２とが一体化して配線用の銅膜１１３が形成される。なお、銅めっき層１１２に対して熱処理を行う代わりに、半導体基板１００を室温下で２日間程度放置しておいても同様の構造が得られる。 Next, after removing the semiconductor substrate 100 from the plating apparatus, the copper plating layer 112 is heat-treated at a temperature of about 100 ° C. for about 2 hours in order to grow crystal grains of the copper plating layer 112. Thereby, as shown in FIG. 5, the seed layer 111 and the copper plating layer 112 are integrated to form a copper film 113 for wiring. Instead of performing the heat treatment on the copper plating layer 112, a similar structure can be obtained by leaving the semiconductor substrate 100 at room temperature for about two days.
次に、図６に示すように、例えばＣＭＰ（Chemical Mechanical Polishing：化学的機械的研磨）法を用いて、配線用溝１０７の外側の、表面に高密度絶縁膜１０９が形成された第２の絶縁膜１０５上に残存する第２のバリア膜１１０及び配線用の銅膜１１３を除去して、銅膜１１３からなるビア１１４及び第２の配線１１５を形成する。これにより、ビア１１４を介して、第１の配線１０３と第２の配線１１５とが接続される。 Next, as shown in FIG. 6, the second high-density insulating film 109 is formed on the surface outside the wiring trench 107 by using, for example, a CMP (Chemical Mechanical Polishing) method. The second barrier film 110 and the wiring copper film 113 remaining on the insulating film 105 are removed, and a via 114 and a second wiring 115 made of the copper film 113 are formed. As a result, the first wiring 103 and the second wiring 115 are connected via the via 114.
その後、必要に応じて、これらの各工程を繰り返すことにより、所望の多層配線構造が形成できる。 Thereafter, a desired multilayer wiring structure can be formed by repeating these steps as necessary.
本実施形態の半導体装置の製造方法は、ビアホール１０６及び配線用溝１０７のそれぞれの底部及び側面に、窒素を含んだ膜厚が１ｎｍ〜５ｎｍ程度の高密度絶縁膜１０９を形成した後、第２のバリア膜１１０を形成する。高密度絶縁膜１０９は第２の絶縁膜１０５と比べて密度が高く、第２の絶縁膜１０５と比べて銅原子の拡散が遅い。従って、第２のバリア膜１１０のバリア性が劣化した部分から染み出してきた銅原子が第２の絶縁膜１０５中に拡散することを抑制できる。また、高密度絶縁膜１０９は窒素を含むため、比誘電率が３．０以下の絶縁膜の場合には特に、シリコン原子の未結合手と窒素との結合が生じ、銅原子の拡散が抑制される。このため、銅原子が第２の絶縁膜１０５中に拡散することを抑制するのに非常に効果的である。窒素は高密度絶縁膜１０９の表面から深さ方向に１ｎｍ〜５ｎｍ程度の深さまで分布するが、その濃度は一定である必要はなく、深くなるに従い減少していてもよい。 The manufacturing method of the semiconductor device according to the present embodiment is performed after forming the high-density insulating film 109 having a thickness of about 1 nm to 5 nm containing nitrogen on the bottom and side surfaces of the via hole 106 and the wiring groove 107. The barrier film 110 is formed. The high-density insulating film 109 has a higher density than the second insulating film 105 and has a slower diffusion of copper atoms than the second insulating film 105. Therefore, it is possible to suppress the copper atoms that have exuded from the portion where the barrier property of the second barrier film 110 has deteriorated from diffusing into the second insulating film 105. In addition, since the high-density insulating film 109 contains nitrogen, particularly in the case of an insulating film having a relative dielectric constant of 3.0 or less, bonds between silicon dangling bonds and nitrogen occur, and diffusion of copper atoms is suppressed. Is done. For this reason, it is very effective in suppressing copper atoms from diffusing into the second insulating film 105. Nitrogen is distributed from the surface of the high-density insulating film 109 to a depth of about 1 nm to 5 nm in the depth direction, but the concentration does not need to be constant and may decrease as the depth increases.
本実施形態において、第２のバリア膜１１０は、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウム若しくは白金の単体又はこれらを２つ以上含む合金等とすればよい。このような白金族元素単体の金属材料及び白金族元素の合金材料等の白金属元素を含む材料は比抵抗が小さい。従って、白金属元素を含む材料をバリア膜とすることにより、配線抵抗及びビア抵抗の増大を防止できる。また、白金属元素を含む材料は融点が高いため、熱安定性にも優れている。さらに、耐酸化性にも優れるため、配線形成プロセス中に金属表面が酸化雰囲気にさらされても密着性が劣化しにくい。多結晶構造の白金族元素を含む材料を用いれば、銅等の配線材料との密着性をさらに向上させることができ。また、これらの材料は、銅との濡れ性も良好であり、埋め込み特性に優れている。 In the present embodiment, the second barrier film 110 may be ruthenium, rhodium, palladium, osmium, iridium, platinum, or an alloy containing two or more of these. Such a metal material containing a platinum group element and a material containing a white metal element such as an alloy material of the platinum group element have a small specific resistance. Therefore, by using a material containing a white metal element as a barrier film, an increase in wiring resistance and via resistance can be prevented. In addition, since a material containing a white metal element has a high melting point, it has excellent thermal stability. Furthermore, since it is excellent in oxidation resistance, even if the metal surface is exposed to an oxidizing atmosphere during the wiring formation process, the adhesion is not easily deteriorated. If a material containing a platinum group element having a polycrystalline structure is used, the adhesion to a wiring material such as copper can be further improved. These materials also have good wettability with copper and have excellent embedding characteristics.
本実施形態において、第１の配線１０３、シード層１１１又は銅めっき層１１２は、銅又は銅合金等の銅を含む材料により形成すればよい。第１のバリア膜１０２は、ルテニウム膜に代えて、タンタル膜又は窒化タンタル膜等を用いてもよい。第１の絶縁膜１０１及び第２の絶縁膜１０５は、二酸化珪素膜、塗布膜又は炭素を含む誘電率の低い膜等を用いてもよい。 In the present embodiment, the first wiring 103, the seed layer 111, or the copper plating layer 112 may be formed of a material containing copper such as copper or a copper alloy. As the first barrier film 102, a tantalum film, a tantalum nitride film, or the like may be used instead of the ruthenium film. As the first insulating film 101 and the second insulating film 105, a silicon dioxide film, a coating film, a film containing carbon having a low dielectric constant, or the like may be used.
本実施形態は、ビアホール１０６と配線用溝１０７とを導電膜により同時に埋め込むデュアルダマシン法の例を示したが、ビアホール１０６と配線用溝１０７とを別々に形成すると共に別々に導電膜を埋め込む方法であっても同様の効果が得られる。 In this embodiment, an example of the dual damascene method in which the via hole 106 and the wiring groove 107 are simultaneously filled with the conductive film is shown. However, the via hole 106 and the wiring groove 107 are separately formed and the conductive film is separately buried. However, the same effect can be obtained.
本実施形態においては、高密度絶縁膜１０９と第２のバリア膜１１０とを別の工程を用いて形成した。しかし、１工程で形成してもよい。この場合、ビアホール１０６及び配線用溝１０７を形成した後、窒素又は窒素とアルゴンとの混合ガス雰囲気において、膜厚が１０ｎｍのルテニウムからなる第２のバリア膜１１０を堆積する。このとき、スパッタのターゲットはルテニウムとする。このようにすれば、膜厚が１ｎｍ〜５ｎｍ程度の窒素を含有する高密度絶縁膜１０９と、ルテニウムからなる第２のバリア膜１１０とを１工程で形成できる。第２のバリア膜１１０を堆積する際に窒素分圧を７５％以上とすると、高密度絶縁膜１０９の窒素濃度を高くすることができ、高密度絶縁膜１０９のバリア性を向上させることができる。また、高密度絶縁膜１０９の窒素濃度は、第２の絶縁膜１０５と接する側から表面側（第２のバリア膜１１０と接する側）に向かって次第に高くなることが好ましい。 In this embodiment, the high-density insulating film 109 and the second barrier film 110 are formed using different processes. However, it may be formed in one step. In this case, after the via hole 106 and the wiring groove 107 are formed, a second barrier film 110 made of ruthenium having a thickness of 10 nm is deposited in an atmosphere of nitrogen or a mixed gas of nitrogen and argon. At this time, the sputtering target is ruthenium. In this way, the high-density insulating film 109 containing nitrogen with a thickness of about 1 nm to 5 nm and the second barrier film 110 made of ruthenium can be formed in one step. If the nitrogen partial pressure is set to 75% or more when the second barrier film 110 is deposited, the nitrogen concentration of the high-density insulating film 109 can be increased, and the barrier property of the high-density insulating film 109 can be improved. . In addition, it is preferable that the nitrogen concentration of the high-density insulating film 109 gradually increases from the side in contact with the second insulating film 105 toward the surface side (side in contact with the second barrier film 110).
図７は、炭素を含む二酸化珪素膜（ＳｉＯＣ膜）膜の上にスパッタ法を用いてルテニウム膜を形成した場合における、ＳｉＯＣ膜とルテニウム膜との界面近傍の断面を示している。図７（ａ）は窒素分圧が９０％の条件でルテニウム膜を形成した場合を示し、図７（ｂ）はアルゴンガス雰囲気においてルテニウム膜を形成した場合を示している。透過型電子顕微鏡による観察の結果、窒素分圧が９０％の条件でスパッタを行った場合には、図７（ａ）に示すようにＳｉＯＣ膜とルテニウム膜との界面において、隣接原子間距離と相対的に対応するリング状模様が小さくなっている。このことから、厚さが３ｎｍ程度の高密度層が形成されていることが明らかとなった。一方、アルゴンガス雰囲気においてスパッタを行った場合には、図７（ｂ）に示すようにリング状模様が小さくなった領域は認められず高密度層の形成は観察されなかった。 FIG. 7 shows a cross section in the vicinity of the interface between the SiOC film and the ruthenium film when a ruthenium film is formed on the silicon dioxide film (SiOC film) film containing carbon by sputtering. FIG. 7A shows a case where a ruthenium film is formed under a condition where the nitrogen partial pressure is 90%, and FIG. 7B shows a case where the ruthenium film is formed in an argon gas atmosphere. As a result of observation with a transmission electron microscope, when sputtering was performed under a condition where the nitrogen partial pressure was 90%, the distance between adjacent atoms at the interface between the SiOC film and the ruthenium film as shown in FIG. The corresponding ring-shaped pattern is relatively small. From this, it became clear that a high-density layer having a thickness of about 3 nm was formed. On the other hand, when sputtering was performed in an argon gas atmosphere, as shown in FIG. 7B, a region where the ring-shaped pattern was reduced was not recognized, and formation of a high-density layer was not observed.
さらに、透過型電子顕微鏡による電子エネルギー損失分光法（ＥＥＬＳ）を用いて元素分析を行った結果、窒素分圧が９０％の条件でスパッタを行った場合にはＳｉＯＣ膜に窒素原子が含まれていることが明らかとなった。このことから、窒素分圧が９０％の条件でスパッタを行った場合には高密度層はＳｉＯＣ（Ｎ）膜となっていると推定される。一方、アルゴンガスのみの条件でスパッタを行った場合には窒素は検出されなかった。 Furthermore, as a result of elemental analysis using electron energy loss spectroscopy (EELS) with a transmission electron microscope, when sputtering is performed under a condition where the nitrogen partial pressure is 90%, the SiOC film contains nitrogen atoms. It became clear that From this, it is estimated that the high-density layer is a SiOC (N) film when sputtering is performed under a condition where the nitrogen partial pressure is 90%. On the other hand, nitrogen was not detected when sputtering was performed only under argon gas.
図８は、ルテニウム膜との界面近傍におけるＳｉＯＣ膜を赤外線吸収法により評価した結果を示している。図８の縦軸は、赤外線吸収から求めたＳｉ−ＣＨ3結合を示すピーク強度とＳｉ−Ｏ結合を示すピークの強度との比である。図８に示すように窒素分圧が９０％の条件でルテニウム膜を形成した場合には、アルゴンガス雰囲気においてルテニウム膜を形成した場合と比べて、Ｓｉ−ＣＨ3／Ｓｉ−Ｏ比の値が低くなっている。このことから、窒素分圧が９０％の条件でルテニウム膜を形成した場合には、ＳｉＯＣ膜中のＳｉ−ＣＨ3結合が減少し、Ｓｉ−Ｏ結合が増加していることが明らかである。つまり、窒素分圧が９０％の条件でルテニウム膜を形成した場合には、界面においてＳｉＯＣ膜の高密度化が生じていることを示している。 FIG. 8 shows the result of evaluating the SiOC film in the vicinity of the interface with the ruthenium film by the infrared absorption method. The vertical axis of FIG. 8 is the ratio of the intensity of a peak indicating a Si-O bond and the peak intensity of the peak indicating Si-CH 3 bond obtained from infrared absorption. As shown in FIG. 8, when the ruthenium film is formed under a condition where the nitrogen partial pressure is 90%, the value of the Si—CH 3 / Si—O ratio is larger than that when the ruthenium film is formed in an argon gas atmosphere. It is low. From this, it is clear that when a ruthenium film is formed under a condition where the nitrogen partial pressure is 90%, Si—CH 3 bonds in the SiOC film are decreased and Si—O bonds are increased. That is, when the ruthenium film is formed under the condition where the nitrogen partial pressure is 90%, the density of the SiOC film is increased at the interface.
図９は、ダイオード構造を用いて加速評価したリーク電流のバリア膜構造依存性を示す。窒素を含む雰囲気においてスパッタを行うことにより高密度絶縁膜を形成した場合には、アルゴンガス雰囲気においてスパッタを行い高密度絶縁膜を形成していない場合と比べて、リーク電流が急激に増加するまでの時間が長く、信頼性が高いことが明らかである。なお、高密度絶縁膜とバリア膜とを同一の工程において形成する場合と、別の工程において形成する場合とではほぼ同じ構造が形成されるため、同様の信頼性を実現できる。 FIG. 9 shows the barrier film structure dependence of the leakage current evaluated using the diode structure. When a high-density insulating film is formed by sputtering in an atmosphere containing nitrogen, the leakage current increases rapidly compared to the case where sputtering is performed in an argon gas atmosphere and no high-density insulating film is formed. It is clear that the time is long and the reliability is high. Note that, when the high-density insulating film and the barrier film are formed in the same process, and in the case of forming in a different process, substantially the same structure is formed, so that the same reliability can be realized.
本発明に係る半導体装置及びその製造方法は、配線の埋め込み不良及び配線抵抗の上昇を抑えると共に、信頼性を向上した半導体装置を実現でき、特に銅等からなる埋め込み配線を有する半導体装置及びその製造方法等として有用である。 The semiconductor device and the manufacturing method thereof according to the present invention can realize a semiconductor device with improved reliability while suppressing poor wiring embedding and an increase in wiring resistance, and in particular, a semiconductor device having an embedded wiring made of copper or the like and the manufacturing thereof. This is useful as a method.
１００ 半導体基板
１０１ 第１の絶縁膜
１０２ 第１のバリア膜
１０３ 第１の配線
１０４ 第１のシリコン窒化膜
１０５ 第２の絶縁膜
１０６ ビアホール
１０７ 配線用溝
１０８ 窒素ガスプラズマ
１０９ 高密度絶縁膜
１１０ 第２のバリア膜
１１１ シード層
１１２ めっき層
１１３ 銅膜
１１４ ビア
１１５ 第２の配線
100 Semiconductor substrate 101 First insulating film 102 First barrier film 103 First wiring 104 First silicon nitride film 105 Second insulating film 106 Via hole 107 Wiring groove 108 Nitrogen gas plasma 109 High-density insulating film 110 First Second barrier film 111 Seed layer 112 Plating layer 113 Copper film 114 Via 115 Second wiring
Claims (11)
前記絶縁膜中に形成された、銅を含む材料からなる埋め込み配線と、
前記絶縁膜と前記埋め込み配線との間に形成された、白金族元素を含む材料からなるバリア膜と、
前記絶縁膜と前記バリア膜との間に形成され、前記絶縁膜よりも密度が高い高密度絶縁膜とを備えていることを特徴とする半導体装置。 An insulating film formed on the substrate;
Embedded wiring made of a material containing copper, formed in the insulating film;
A barrier film made of a material containing a platinum group element, formed between the insulating film and the embedded wiring;
A semiconductor device comprising: a high-density insulating film formed between the insulating film and the barrier film and having a higher density than the insulating film.
前記絶縁膜に凹部を形成する工程（ｂ）と、
前記凹部の側面に前記絶縁膜と比べて密度が高い高密度絶縁膜を形成する工程（ｃ）と、
前記工程（ｃ）よりも後に、前記凹部の内面に沿って、白金族元素を含む材料からなるバリア膜を形成する工程（ｄ）と、
前記工程（ｄ）よりも後に、凹部の内面に沿って、銅を含む材料からなる第１の導電膜を順次形成する工程（ｅ）と、
前記第１の導電膜の上に、前記凹部を埋めるように銅を含む材料からなる第２の導電膜を成長させる工程（ｆ）と、
前記工程（ｆ）よりも後に、前記第１の導電膜と前記第２の導電膜とを一体化して埋め込み配線を形成する工程（ｇ）とを備えていることを特徴とする半導体装置の製造方法。 Forming an insulating film on the semiconductor substrate (a);
Forming a recess in the insulating film (b);
A step (c) of forming a high-density insulating film having a higher density than the insulating film on the side surface of the recess;
A step (d) of forming a barrier film made of a material containing a platinum group element along the inner surface of the concave portion after the step (c);
After the step (d), a step (e) of sequentially forming a first conductive film made of a material containing copper along the inner surface of the recess;
A step (f) of growing a second conductive film made of a material containing copper on the first conductive film so as to fill the recess;
A step (g) of forming a buried wiring by integrating the first conductive film and the second conductive film after the step (f) is manufactured. Method.
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