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JP5204376B2 - Metal film polishing composition and method for producing metal film polishing composition - Google Patents

Metal film polishing composition and method for producing metal film polishing composition Download PDF

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JP5204376B2
JP5204376B2 JP2006018125A JP2006018125A JP5204376B2 JP 5204376 B2 JP5204376 B2 JP 5204376B2 JP 2006018125 A JP2006018125 A JP 2006018125A JP 2006018125 A JP2006018125 A JP 2006018125A JP 5204376 B2 JP5204376 B2 JP 5204376B2
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metal film
polishing composition
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film polishing
fumed silica
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JP2007201187A (en
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慶治 太田
利香 田中
浩士 新田
善隆 森岡
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Nitta DuPont Inc
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Description

本発明は、CMP研磨処理に用いる研磨用組成物であり、特に金属膜を研磨するときに使用する金属膜研磨用組成物および金属膜研磨用組成物の製造方法に関する。   The present invention relates to a polishing composition used for CMP polishing treatment, and particularly relates to a metal film polishing composition used when polishing a metal film and a method for producing the metal film polishing composition.

半導体製造の分野では、半導体素子の微細化および多層化による高集積化に伴い、半導体層、金属層の平坦化技術が重要な要素技術となっている。ウエハに集積回路を形成する際、電極配線などによる凹凸を平坦化せずに層を重ねると、段差が大きくなり、平坦性が極端に悪くなる。また段差が大きくなった場合、フォトリソグラフィにおいて凹部と凸部の両方に焦点を合わせることが困難になり微細化を実現することができなくなる。したがって、積層中の然るべき段階でウエハ表面の凹凸を除去するための平坦化処理を行う必要がある。平坦化処理には、エッチングにより凹凸部を除去するエッチバック法、プラズマCVD(Chemical Vapor Deposition)などにより平坦な膜を形成する成膜法、熱処理によって平坦化する流動化法、選択CVDなどにより凹部の埋め込みを行う選択成長法などがある。   In the field of semiconductor manufacturing, with the high integration by miniaturization and multilayering of semiconductor elements, the planarization technology of semiconductor layers and metal layers has become an important elemental technology. When forming an integrated circuit on a wafer, if the layers are stacked without flattening the unevenness due to electrode wiring or the like, the step becomes large and the flatness becomes extremely poor. Further, when the step becomes large, it becomes difficult to focus on both the concave portion and the convex portion in photolithography, and miniaturization cannot be realized. Therefore, it is necessary to perform a planarization process for removing irregularities on the wafer surface at an appropriate stage during the lamination. For the flattening process, an etching back method for removing uneven portions by etching, a film forming method for forming a flat film by plasma CVD (Chemical Vapor Deposition), a fluidizing method for flattening by heat treatment, a concave portion by selective CVD, etc. There is a selective growth method for embedding.

以上の方法は、絶縁膜、金属膜など膜の種類によって適否があること、また平坦化できる領域がきわめて狭いという問題がある。このような問題を克服することができる平坦化処理技術としてCMP(Chemical Mechanical Polishing)による平坦化がある。   The above method has problems that it is appropriate depending on the type of film such as an insulating film and a metal film, and that the region that can be flattened is extremely narrow. As a planarization technique that can overcome such problems, there is planarization by CMP (Chemical Mechanical Polishing).

CMPによる平坦化処理では、微細なシリカ粒子(砥粒)を懸濁した研磨用組成物を研磨パッド表面に供給しながら、圧接した研磨パッドと、被研磨物であるシリコンウエハとを相対移動させて表面を研磨することにより、広範囲にわたるウエハ表面を高精度に平坦化することができる。   In the flattening process by CMP, while the polishing composition in which fine silica particles (abrasive grains) are suspended is supplied to the surface of the polishing pad, the pressed polishing pad and the silicon wafer as the object to be polished are relatively moved. By polishing the surface, the wafer surface over a wide range can be flattened with high accuracy.

タングステン(W)などの金属膜の平坦化工程では、まず高い研磨レートの1次研磨によって大幅に金属膜を除去し、バフ研磨によって仕上げを行う。このバフ研磨において、一次研磨と同様の研磨用組成物(スラリー)を使用すると、金属膜が過剰に研磨されてしまい、ディッシング、エロージョンが発生してしまう。このため、バフ研磨用のスラリーとしては、金属膜研磨速度と酸化膜研磨速度との比である選択比が小さくなるようなスラリー(非選択性スラリー)を用いる必要がある。選択比が小さいと、金属膜と酸化膜とがほぼ同じ研磨レートで研磨されるのでディッシングおよびエロージョンの発生が抑制される。   In the planarization process of a metal film such as tungsten (W), first, the metal film is largely removed by primary polishing at a high polishing rate, and finishing is performed by buffing. In this buffing, if a polishing composition (slurry) similar to the primary polishing is used, the metal film is excessively polished, and dishing and erosion occur. For this reason, as the slurry for buff polishing, it is necessary to use a slurry (non-selective slurry) in which the selection ratio, which is the ratio between the metal film polishing rate and the oxide film polishing rate, is small. When the selection ratio is small, the metal film and the oxide film are polished at substantially the same polishing rate, so that the occurrence of dishing and erosion is suppressed.

バフ研磨用の非選択性スラリーとしては、たとえば、砥粒であるコロイダルシリカと酸化剤とを含み、酸化剤の働きを考慮してpH調整されたものが用いられる(たとえば特許文献1参照)。
また、特許文献2には、金属層、障壁層、絶縁層に対する除去速度が実質的に同一である非選択性スラリーが開示されている。この非選択性スラリーは、研磨材(砥粒)と、第2酸化剤を酸化するための第1酸化剤と、第1酸化剤により酸化され再び酸化力が復元される第2酸化剤と、障壁層の研磨速度を増加させるための添加剤(pH調整剤)とを含んで構成される。第1酸化剤としては、過酸化化合物が用いられ、第2酸化剤としては、鉄化合物が用いられる。研磨材としては、アルミナ、シリカ、セリアが好ましく用いられ、コロイダルシリカが特に好ましく用いられる。
As the non-selective slurry for buffing, for example, a slurry containing colloidal silica that is abrasive grains and an oxidizing agent and adjusted in pH in consideration of the function of the oxidizing agent is used (see, for example, Patent Document 1).
Patent Document 2 discloses a non-selective slurry having substantially the same removal rate with respect to a metal layer, a barrier layer, and an insulating layer. The non-selective slurry includes an abrasive (abrasive grains), a first oxidant for oxidizing the second oxidant, a second oxidant that is oxidized by the first oxidant and restores the oxidizing power again, And an additive (pH adjuster) for increasing the polishing rate of the barrier layer. A peroxide compound is used as the first oxidizing agent, and an iron compound is used as the second oxidizing agent. As the abrasive, alumina, silica, and ceria are preferably used, and colloidal silica is particularly preferably used.

特開平9−167797号公報Japanese Patent Laid-Open No. 9-167797 特開2001−210612号公報Japanese Patent Laid-Open No. 2001-210612

コロイダルシリカは、その製造工程上、ナトリウム(Na)、カリウム(K)、鉄(Fe)、クロム(Cr)、ニッケル(Ni)、銅(Cu)などの不純物金属を多く含むため、砥粒としてコロイダルシリカを用いたスラリーにも不純物金属が含まれることになる。このような不純物金属は、研磨時にシリコンウエハの表面を汚染してしまう。   Colloidal silica contains a large amount of impurity metals such as sodium (Na), potassium (K), iron (Fe), chromium (Cr), nickel (Ni), copper (Cu), etc. in its manufacturing process. Impurity metals are also contained in the slurry using colloidal silica. Such an impurity metal contaminates the surface of the silicon wafer during polishing.

不純物金属の含有量がコロイダルシリカよりも大幅に少ないヒュームドシリカを、コロイダルシリカの代わりに砥粒として用いると、不純物金属による汚染は防ぐことができるが、酸化膜研磨速度が遅くなり、選択比が大きくなってしまうので、ディッシングおよびエロージョンの発生を抑制することができない。不純物金属を除去した高純度コロイダルシリカも存在するが、流通量が少なく、高価であるため、実用は困難である。
また、コロイダルシリカを用いないとしても、特許文献2記載のスラリーのように、酸化剤として硝酸第二鉄などの鉄化合物を添加したスラリーである場合は、重金属である鉄によってシリコンウエハ表面が汚染されるため、仕上げ工程であるバフ研磨工程には使用不可能である。
When fumed silica, which contains significantly less impurity metal than colloidal silica, is used as abrasive grains instead of colloidal silica, contamination by impurity metal can be prevented, but the oxide film polishing rate becomes slower and the selectivity ratio is reduced. Therefore, the occurrence of dishing and erosion cannot be suppressed. Although high-purity colloidal silica from which impurity metals have been removed also exists, it is difficult to put it to practical use because of its low circulation and high price.
Further, even if colloidal silica is not used, when the slurry is a slurry in which an iron compound such as ferric nitrate is added as an oxidizing agent as in the slurry described in Patent Document 2, the silicon wafer surface is contaminated by iron which is a heavy metal Therefore, it cannot be used for the buffing process which is a finishing process.

本発明の目的は、ヒュームドシリカを用いても選択比を小さくすることができる金属膜研磨用組成物、および金属膜研磨用組成物の製造方法を提供することである。   An object of the present invention is to provide a metal film polishing composition capable of reducing the selectivity even when fumed silica is used, and a method for producing the metal film polishing composition.

本発明は、タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物であって、
砥粒であるヒュームドシリカと酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上とpH調整剤とを有し、pHが6〜8.5であることを特徴とする金属膜研磨用組成物である。
The present invention is a metal film polishing composition for polishing a tungsten film and a TEOS film,
It has 1 or 2 or more types selected from the group consisting of fumed silica that is abrasive grains and iodate, chlorate compound, and bromate compound that are oxidizers, and a pH adjuster of 6 to The composition for polishing a metal film is 8.5.

また本発明は、前記pH調整剤は、水酸化アンモニウム、水酸化カリウム、水酸化カルシウム、水酸化マグネシウム、炭酸水素カリウム、炭酸カリウムからなる群より選ばれる1種または2種以上であることを特徴とする。
また本発明は、金属膜平坦化処理の仕上げ工程であるバフ研磨工程で用いられる、タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物であって、
砥粒であるヒュームドシリカと、重金属を含まない酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上と、重金属を含まないpH調整剤とを有し、pHが6〜8.5であることを特徴とする金属膜研磨用組成物である。
In the present invention, the pH adjuster is one or more selected from the group consisting of ammonium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, potassium hydrogen carbonate, and potassium carbonate. And
Further, the present invention is a metal film polishing composition for polishing a tungsten film and a TEOS film, which is used in a buff polishing process which is a finishing process of a metal film flattening process,
One or more selected from the group consisting of fumed silica that is abrasive grains and iodate, chlorate compound, and bromate compound that are oxidizers that do not contain heavy metals, and pH adjustment that does not contain heavy metals And a metal film polishing composition characterized by having a pH of 6 to 8.5.

また本発明は、タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物を製造する金属膜研磨用組成物の製造方法であって、
混合後のpHが6〜8.5となるように、砥粒であるヒュームドシリカとpH調整剤とを含む砥粒分散液、および酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上を含む酸化剤溶液を調製する工程と、
前記砥粒分散液と前記酸化剤溶液とを混合する工程とを有することを特徴とする金属膜研磨用組成物の製造方法である。
The present invention also provides a method for producing a metal film polishing composition for producing a metal film polishing composition for polishing a tungsten film and a TEOS film,
An abrasive dispersion containing fumed silica that is abrasive grains and a pH adjuster, and an iodate, chlorate compound, and bromic acid that are oxidizing agents so that the pH after mixing is 6 to 8.5. Preparing an oxidizer solution containing one or more selected from the group consisting of salt compounds ;
A method for producing a metal film polishing composition comprising the step of mixing the abrasive dispersion and the oxidant solution.

本発明によれば、タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物であって、砥粒であるヒュームドシリカと酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上とpH調整剤とを含み、pHが6〜8.5である。 According to the present invention, a metal film polishing composition for polishing a tungsten film and a TEOS film, comprising fumed silica as an abrasive grain and iodate, chlorate compound, bromic acid as an oxidizing agent. 1 type or 2 types or more selected from the group which consists of a salt compound and a pH adjuster are included, and pH is 6-8.5.

このようなpHでは、酸化膜研磨速度が増大し、金属膜研磨速度に近づくことで、ヒュームドシリカを使用しても選択比を0.5〜2.0と小さくすることができる。ヒュームドシリカを使用するので、不純物金属をほとんど含まない金属膜研磨用組成物が安価で大量に得られる。   At such a pH, the oxide film polishing rate increases, and by approaching the metal film polishing rate, the selectivity can be reduced to 0.5 to 2.0 even when fumed silica is used. Since fumed silica is used, a metal film polishing composition containing almost no impurity metal can be obtained at a low cost and in a large amount.

た、前記酸化剤としては、ヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上を用いることができる。 Also, examples of the oxidizing agent can be used iodate, chlorate compounds, one or more selected from the group consisting of bromate compound.

また本発明によれば、前記pH調整剤としては、水酸化アンモニウム、水酸化カリウム、水酸化カルシウム、水酸化マグネシウム、炭酸水素カリウム、炭酸カリウムからなる群より選ばれる1種または2種以上を用いることができる。
また本発明によれば、金属膜平坦化処理の仕上げ工程であるバフ研磨工程で好適に用いられる、タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物である。
砥粒であるヒュームドシリカと、重金属を含まない酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上と、重金属を含まないpH調整剤とを有し、pHが6〜8.5であることを特徴とする金属膜研磨用組成物である。
このようなpHでは、酸化膜研磨速度が増大し、金属膜研磨速度に近づくことで、ヒュームドシリカを使用しても選択比を0.5〜2.0と小さくすることができる。重金属を含まない酸化剤と、重金属を含まないpH調整剤とを含んでおり、かつヒュームドシリカを使用するので、重金属などの不純物金属をほとんど含まないバフ研磨用組成物が安価で大量に得られる。
According to the invention, as the pH adjuster, one or more selected from the group consisting of ammonium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, potassium hydrogen carbonate, and potassium carbonate are used. be able to.
Moreover, according to this invention, it is a metal film polishing composition for grind | polishing a tungsten film and a TEOS film | membrane suitably used at the buffing process which is a finishing process of a metal film planarization process.
One or more selected from the group consisting of fumed silica that is abrasive grains and iodate, chlorate compound, and bromate compound that are oxidizers that do not contain heavy metals, and pH adjustment that does not contain heavy metals And a metal film polishing composition characterized by having a pH of 6 to 8.5.
At such a pH, the oxide film polishing rate increases, and by approaching the metal film polishing rate, the selectivity can be reduced to 0.5 to 2.0 even when fumed silica is used. Because it contains an oxidizing agent that does not contain heavy metals and a pH adjuster that does not contain heavy metals, and fumed silica is used, a buffing composition that contains almost no impurities such as heavy metals can be obtained in large quantities at low cost. It is done.

また本発明によれば、上記の金属膜研磨用組成物は、混合後のpHが6〜8.5となるように、砥粒であるヒュームドシリカとpH調整剤とを含む砥粒分散液、および酸化剤を含む酸化剤溶液を予め調製しておき、研磨を行う前に前記砥粒分散液と前記酸化剤溶液とを混合してから供給することが好ましい。   Moreover, according to this invention, said metal film polishing composition is an abrasive grain dispersion liquid containing fumed silica which is an abrasive grain, and a pH adjuster so that pH after mixing may be 6-8.5. It is preferable that an oxidant solution containing oxidant and oxidant is prepared in advance, and the abrasive dispersion and the oxidant solution are mixed and supplied before polishing.

上記の金属膜研磨用組成物は、長期間の保管によって凝集が発生する可能性があるため、砥粒分散液と酸化剤溶液の状態で保管しておくことで凝集の発生を抑制することができる。   Since the metal film polishing composition described above may be aggregated by long-term storage, it can be suppressed by storing it in the state of an abrasive dispersion and an oxidant solution. it can.

本発明は、砥粒であるヒュームドシリカと酸化剤とpH調整剤とを含み、pHが6〜8.5であることを特徴とする金属膜研磨用組成物であり、特に金属膜平坦化処理の仕上げ工程であるバフ研磨工程で好適に用いられる。   The present invention is a metal film polishing composition comprising fumed silica as abrasive grains, an oxidizing agent, and a pH adjuster, and having a pH of 6 to 8.5, and in particular, a metal film flattening It is suitably used in a buffing process that is a finishing process of the treatment.

ヒュームドシリカを砥粒として用いて、pHを中性付近とすることで金属膜研磨速度と酸化膜研磨速度との比である選択比を小さくすることができる。   By using fumed silica as abrasive grains and setting the pH to near neutrality, the selectivity, which is the ratio between the metal film polishing rate and the oxide film polishing rate, can be reduced.

金属膜研磨用組成物のpH範囲は6〜8.5が好ましく、より好ましくは6.5〜8である。pHが6〜8.5では、酸化膜研磨速度が増大し、金属膜研磨速度に近づくことで選択比が0.5〜2.0となる。選択比が0.5より小さくなると酸化膜が必要以上に研磨されてしまい、選択比が2.0より大きくなるとディッシングおよびエロージョンの抑制効果が発揮されない。   The pH range of the metal film polishing composition is preferably 6 to 8.5, more preferably 6.5 to 8. When the pH is 6 to 8.5, the oxide film polishing rate is increased, and the selectivity becomes 0.5 to 2.0 by approaching the metal film polishing rate. When the selection ratio is less than 0.5, the oxide film is polished more than necessary, and when the selection ratio is more than 2.0, the effect of suppressing dishing and erosion is not exhibited.

ヒュームドシリカの含有量は、特に制限されず、既存の金属膜研磨用組成物と同程度、たとえば金属膜研磨用組成物全体に対して0.1重量%以上25重量%以下とする。0.1重量%未満では砥粒としての働きが十分でなく、25重量%を超える場合は他の成分の含有量に影響を及ぼすため好ましくない。   The content of fumed silica is not particularly limited, and is about the same as that of an existing metal film polishing composition, for example, 0.1 wt% or more and 25 wt% or less with respect to the entire metal film polishing composition. If it is less than 0.1% by weight, the function as abrasive grains is not sufficient, and if it exceeds 25% by weight, the content of other components is affected.

酸化剤は、ヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上であり、重金属を含まないものが好ましく、ヨウ素酸カリウム、臭素酸カリウムが特に好ましい。   The oxidizing agent is one or more selected from the group consisting of an iodate, a chlorate compound, and a bromate compound, preferably does not contain heavy metals, and potassium iodate and potassium bromate are particularly preferable. .

pH調整剤は、水酸化アンモニウム、水酸化カリウム、水酸化カルシウム、水酸化マグネシウム、炭酸水素カリウム、炭酸カリウムからなる群より選ばれる1種または2種以上であり、重金属を含まないものが好ましく、水酸化カリウムが特に好ましい。   The pH adjuster is one or more selected from the group consisting of ammonium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, potassium bicarbonate, potassium carbonate, and preferably does not contain heavy metals. Potassium hydroxide is particularly preferred.

酸化剤およびpH調整剤の含有量は、特に制限されず、既存の金属膜研磨用組成物と同程度、たとえば金属膜研磨用組成物全体に対して、酸化剤であれば0.01重量%以上5.00重量%以下、pH調整剤であれば0.001重量%以上0.05重量%以下とする。   The content of the oxidizing agent and the pH adjusting agent is not particularly limited, and is about the same as that of an existing metal film polishing composition, for example, 0.01% by weight of an oxidizing agent with respect to the entire metal film polishing composition. If it is a pH adjuster, it will be 0.001 to 0.05 weight%.

本発明の金属膜研磨用組成物は、長期間に渡って静置保存した場合、砥粒が凝集することによって研磨傷が発生することがある。したがって、pH調整剤の水溶液中にヒュームドシリカを分散させた砥粒分散液と、酸化剤の水溶液である酸化剤溶液とを予め調製しておき、研磨を行う前に混合して供給することが好ましい。   When the composition for polishing a metal film of the present invention is stored for a long period of time, polishing scratches may occur due to aggregation of abrasive grains. Accordingly, an abrasive dispersion in which fumed silica is dispersed in an aqueous solution of a pH adjusting agent and an oxidizer solution that is an aqueous solution of an oxidizer are prepared in advance and mixed and supplied before polishing. Is preferred.

砥粒分散液と酸化剤溶液とは、たとえば1:1〜7:1の比で混合する。このとき、砥粒分散液におけるヒュームドシリカの含有量は0.1重量%以上25重量%以下とし、pH調整剤の含有量は0.001重量%以上0.05重量%以下とする。酸化剤溶液における酸化剤の含有量は0.01重量%以上5.00重量%以下とする。   The abrasive dispersion and the oxidizer solution are mixed at a ratio of 1: 1 to 7: 1, for example. At this time, the fumed silica content in the abrasive dispersion is 0.1 wt% or more and 25 wt% or less, and the pH adjuster content is 0.001 wt% or more and 0.05 wt% or less. The content of the oxidizing agent in the oxidizing agent solution is set to 0.01% by weight or more and 5.00% by weight or less.

砥粒分散液と酸化剤溶液とを混合槽内で混合する際には、混合槽内での高さ方向の濃度勾配が発生しない程度にプロペラ型撹拌機による撹拌または循環を行うことが好ましい。ただし、金属膜研磨用組成物の使用時間が短い場合、すなわち砥粒が混合槽内で沈降しない程度の時間(たとえば3時間程度)であれば、混合初期に一度混合槽内を均一化するだけで使用可能である。   When the abrasive dispersion and the oxidant solution are mixed in the mixing tank, it is preferable to perform stirring or circulation with a propeller-type stirrer to such an extent that a concentration gradient in the height direction does not occur in the mixing tank. However, if the usage time of the metal film polishing composition is short, that is, if the abrasive grains do not settle in the mixing tank (for example, about 3 hours), the mixing tank is only homogenized once in the initial stage of mixing. Can be used.

以下では、金属膜研磨用組成物の選択比に対するpHの影響について説明する。また、比較のためにコロイダルシリカを用いた金属膜研磨用組成物の選択比についても検討した。
選択比の測定を行った金属膜研磨用組成物の組成を示す。
Below, the influence of pH with respect to the selection ratio of the composition for metal film polishing is demonstrated. For comparison, the selection ratio of the metal film polishing composition using colloidal silica was also examined.
The composition of the metal film polishing composition for which the selectivity was measured is shown.

(検討例1)
砥粒:ヒュームドシリカ 20重量%
pH調整剤:塩酸(0.1mol/l) 1重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:2.0
(Examination example 1)
Abrasive grain: Fumed silica 20% by weight
pH adjuster: hydrochloric acid (0.1 mol / l) 1% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 2.0

(検討例2)
砥粒:ヒュームドシリカ 20重量%
pH調整剤:水酸化アンモニウム 0.01重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:6.7
(Examination example 2)
Abrasive grain: Fumed silica 20% by weight
pH adjuster: ammonium hydroxide 0.01% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 6.7

(検討例3)
砥粒:ヒュームドシリカ 20重量%
pH調整剤:水酸化アンモニウム 0.015重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:7.3
(Examination example 3)
Abrasive grain: Fumed silica 20% by weight
pH adjuster: ammonium hydroxide 0.015% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 7.3

(検討例4)
砥粒:ヒュームドシリカ 20重量%
pH調整剤:水酸化アンモニウム 0.02重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:8.0
(Examination example 4)
Abrasive grain: Fumed silica 20% by weight
pH adjuster: ammonium hydroxide 0.02% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 8.0

(検討例5)
砥粒:ヒュームドシリカ 20重量%
pH調整剤:水酸化アンモニウム 0.04重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:8.7
(Examination example 5)
Abrasive grain: Fumed silica 20% by weight
pH adjuster: ammonium hydroxide 0.04% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 8.7

(検討例6)
砥粒:ヒュームドシリカ 20重量%
pH調整剤:水酸化アンモニウム 0.06重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:9.2
(Examination example 6)
Abrasive grain: Fumed silica 20% by weight
pH adjuster: ammonium hydroxide 0.06% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 9.2

(検討例7)
砥粒:コロイダルシリカ 20重量%
pH調整剤:塩酸(1mol/l) 1重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:2.0
(Examination example 7)
Abrasive grain: Colloidal silica 20% by weight
pH adjuster: hydrochloric acid (1 mol / l) 1% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 2.0

(検討例8)
砥粒:コロイダルシリカ 20重量%
pH調整剤:塩酸(1mol/l) 0.1重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:3.0
(Examination example 8)
Abrasive grain: Colloidal silica 20% by weight
pH adjuster: hydrochloric acid (1 mol / l) 0.1% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 3.0

(検討例9)
砥粒:コロイダルシリカ 20重量%
pH調整剤:塩酸(1mol/l) 0.01重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:4.0
(Examination example 9)
Abrasive grain: Colloidal silica 20% by weight
pH adjuster: hydrochloric acid (1 mol / l) 0.01% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 4.0

(検討例10)
砥粒:コロイダルシリカ 20重量%
pH調整剤:添加せず 0重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:7.0
(Examination example 10)
Abrasive grain: Colloidal silica 20% by weight
pH adjuster: 0% by weight without addition
Oxidizing agent: potassium iodate 0.83% by weight
pH: 7.0

(検討例11)
砥粒:コロイダルシリカ 20重量%
pH調整剤:水酸化アンモニウム 0.15重量%
酸化剤:ヨウ素酸カリウム 0.83重量%
pH:10.0
(Examination example 11)
Abrasive grain: Colloidal silica 20% by weight
pH adjuster: ammonium hydroxide 0.15% by weight
Oxidizing agent: potassium iodate 0.83% by weight
pH: 10.0

上記の各検討例を用いて金属膜であるタングステン(W)膜および酸化膜であるTEOS(Tetraethoxysilane)膜の研磨を行い、研磨レートを測定した。研磨レートは、単位時間当たりに研磨によって除去された膜厚み(Å)である。   The tungsten (W) film, which is a metal film, and the TEOS (Tetraethoxysilane) film, which is an oxide film, were polished using each of the above study examples, and the polishing rate was measured. The polishing rate is the film thickness (Å) removed by polishing per unit time.

なお、各検討例は、ヒュームドシリカまたはコロイダルシリカを25重量%含む砥粒分散液と、ヨウ素酸カリウムを4.15重量%含む酸化剤溶液とを予め調製しておき、研磨を行う直前に、砥粒分散液と酸化剤溶液とを4:1の比で混合して使用した。pH調整剤は、混合後の含有量が上記の含有量となるように砥粒分散液に添加する。ヒュームドシリカおよびコロイダルシリカの体積平均粒子径は、レーザ回折/散乱式粒度分布測定装置(堀場製作所製、LA−920)で測定し、85nmであった。   In each of the study examples, an abrasive dispersion containing 25% by weight of fumed silica or colloidal silica and an oxidant solution containing 4.15% by weight of potassium iodate were prepared in advance and immediately before polishing. The abrasive dispersion and the oxidant solution were mixed at a ratio of 4: 1. The pH adjuster is added to the abrasive dispersion so that the content after mixing is the above content. The volume average particle size of fumed silica and colloidal silica was 85 nm as measured with a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.).

図1は、pHを変化させたときの金属膜研磨レートおよび酸化膜研磨レートを示すグラフである。縦軸が研磨レート(Å/min)を示し、横軸がpH(−)を示す。折れ線1は、ヒュームドシリカを用いた検討例1〜6の金属膜研磨レートを示し、折れ線2は、ヒュームドシリカを用いた検討例1〜6の酸化膜研磨レートを示し、折れ線3は、コロイダルシリカを用いた検討例7〜11の金属膜研磨レートを示し、折れ線4は、コロイダルシリカを用いた検討例7〜11の酸化膜研磨レートを示す。   FIG. 1 is a graph showing a metal film polishing rate and an oxide film polishing rate when pH is changed. The vertical axis represents the polishing rate (Å / min), and the horizontal axis represents pH (−). The polygonal line 1 shows the metal film polishing rate of the examination examples 1 to 6 using fumed silica, the polygonal line 2 shows the oxide film polishing rate of the examination examples 1 to 6 using fumed silica, and the polygonal line 3 is The metal film polishing rate of the examination examples 7-11 using colloidal silica is shown, and the broken line 4 shows the oxide film polishing rate of the examination examples 7-11 using colloidal silica.

W膜研磨時およびTEOS膜研磨時の研磨レートは以下のような条件で測定した。
研磨機:SH−24(speed FAM社製)
研磨パッド:IC1400(ニッタ・ハース社製)
研磨パッド回転数:65rpm
キャリア回転数 :65rpm
スラリー流量 :125ml/min
研磨時間 :60秒間
研磨加重 :5psi(3.4×10Pa)
The polishing rate during W film polishing and TEOS film polishing was measured under the following conditions.
Polishing machine: SH-24 (manufactured by speed FAM)
Polishing pad: IC1400 (Nitta Haas)
Polishing pad rotation speed: 65rpm
Carrier rotation speed: 65rpm
Slurry flow rate: 125 ml / min
Polishing time: 60 seconds Polishing load: 5 psi (3.4 × 10 4 Pa)

グラフの折れ線1および折れ線2からわかるように、pHが6〜8.5の範囲では、選択比が0.5〜2.0となった。また、折れ線3および折れ線4を見ると、コロイダルシリカを用いた場合でも選択比が小さくなるpH範囲が存在するが、金属膜研磨レートまたは酸化膜研磨レートが500Å/min以下でしかなく、たとえ選択比が小さいとしても、研磨レート自体が低すぎるために実用性を有していない。   As can be seen from the broken line 1 and the broken line 2 in the graph, the selectivity was 0.5 to 2.0 when the pH was in the range of 6 to 8.5. In addition, when the polygonal line 3 and the polygonal line 4 are viewed, there is a pH range where the selection ratio is small even when colloidal silica is used, but the metal film polishing rate or the oxide film polishing rate is only 500 Å / min or less, even if selected. Even if the ratio is small, the polishing rate itself is too low to have practicality.

このようにpH範囲を適切な範囲とすることで、ヒュームドシリカを使用しても選択比を0.5〜2.0と小さくすることができる。また、重金属を含まない酸化剤と、重金属を含まないpH調整剤とを含んでおり、かつヒュームドシリカを使用するので、重金属などの不純物金属をほとんど含まない金属膜研磨用組成物を安価で大量に得ることができる。   By setting the pH range to an appropriate range as described above, the selectivity can be reduced to 0.5 to 2.0 even when fumed silica is used. In addition, since it contains an oxidizing agent that does not contain heavy metals and a pH adjuster that does not contain heavy metals, and fumed silica is used, a metal film polishing composition that contains almost no impurity metals such as heavy metals can be produced at low cost. Can be obtained in large quantities.

図2は、静置保管時の金属膜研磨用組成物の粘度の経時変化を示すグラフである。縦軸は粘度(cP)を示し、横軸は保管日数(日)を示す。なお、1cP=1×10−3Pa・sである。折れ線5は、混合後の検討例4を静置保管したときの粘度を示しており、折れ線6は、検討例4の砥粒分散液のみを静置保管したときの粘度を示している。グラフからわかるように、混合後の金属膜研磨用組成物は保管日数の経過にしたがって粘度が増加しており、凝集が生じている可能性が大きいが、砥粒分散液のみでは粘度の変化はほとんどなく、凝集は生じていない。したがって、砥粒分散液と酸化剤溶液の状態で保管しておくことで凝集の発生を抑制することができる。 FIG. 2 is a graph showing the change over time in the viscosity of the metal film polishing composition during stationary storage. The vertical axis represents viscosity (cP), and the horizontal axis represents storage days (days). Note that 1cP = 1 × 10 −3 Pa · s. A polygonal line 5 indicates the viscosity when the examination example 4 after mixing is stored stationary, and a polygonal line 6 indicates the viscosity when the abrasive dispersion liquid of the examination example 4 alone is stored stationary. As can be seen from the graph, the composition for polishing a metal film after mixing increases in viscosity with the passage of storage days, and there is a high possibility that agglomeration has occurred. There is almost no aggregation. Therefore, the occurrence of agglomeration can be suppressed by storing in the state of the abrasive dispersion and the oxidant solution.

図3は、循環使用時の金属膜研磨用組成物の粘度の経時変化を示すグラフである。縦軸は粘度(cP)を示し、横軸は循環日数(日)を示す。折れ線7は、混合後の検討例4を循環使用したときの粘度を示している。グラフからわかるように、循環させることで、混合後の金属膜研磨用組成物であっても粘度は増加せず凝集が生じていない。   FIG. 3 is a graph showing the change over time in the viscosity of the metal film polishing composition during use in circulation. The vertical axis represents viscosity (cP), and the horizontal axis represents the number of days of circulation (days). A broken line 7 indicates the viscosity when the examination example 4 after mixing is used in a circulating manner. As can be seen from the graph, by circulating, the viscosity does not increase and aggregation does not occur even in the metal film polishing composition after mixing.

pHを変化させたときの金属膜研磨レートおよび酸化膜研磨レートを示すグラフである。It is a graph which shows the metal film polishing rate and oxide film polishing rate when changing pH. 静置保管時の金属膜研磨用組成物の粘度の経時変化を示すグラフである。It is a graph which shows the time-dependent change of the viscosity of the metal film polishing composition at the time of stationary storage. 循環使用時の金属膜研磨用組成物の粘度の経時変化を示すグラフである。It is a graph which shows a time-dependent change of the viscosity of the metal film polishing composition at the time of circulation use.

Claims (4)

タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物であって、
砥粒であるヒュームドシリカと酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上とpH調整剤とを有し、pHが6〜8.5であることを特徴とする金属膜研磨用組成物。
A metal film polishing composition for polishing a tungsten film and a TEOS film,
It has 1 or 2 or more types selected from the group consisting of fumed silica that is abrasive grains and iodate, chlorate compound, and bromate compound that are oxidizers, and a pH adjuster of 6 to A metal film polishing composition, which is 8.5.
前記pH調整剤は、水酸化アンモニウム、水酸化カリウム、水酸化カルシウム、水酸化マグネシウム、炭酸水素カリウム、炭酸カリウムからなる群より選ばれる1種または2種以上であることを特徴とする請求項1記載の金属膜研磨用組成物。   2. The pH adjusting agent is one or more selected from the group consisting of ammonium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, potassium hydrogen carbonate, and potassium carbonate. The metal film polishing composition as described. 金属膜平坦化処理の仕上げ工程であるバフ研磨工程で用いられる、タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物であって、
砥粒であるヒュームドシリカと、重金属を含まない酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上と、重金属を含まないpH調整剤とを有し、pHが6〜8.5であることを特徴とする金属膜研磨用組成物。
A metal film polishing composition for polishing a tungsten film and a TEOS film, which is used in a buff polishing process which is a finishing process of a metal film flattening process,
One or more selected from the group consisting of fumed silica that is abrasive grains and iodate, chlorate compound, and bromate compound that are oxidizers that do not contain heavy metals, and pH adjustment that does not contain heavy metals And a metal film polishing composition characterized by having a pH of 6 to 8.5.
タングステン膜とTEOS膜とを研磨するための金属膜研磨用組成物を製造する金属膜研磨用組成物の製造方法であって、
混合後のpHが6〜8.5となるように、砥粒であるヒュームドシリカとpH調整剤とを含む砥粒分散液、および酸化剤であるヨウ素酸塩、塩素酸塩化合物、臭素酸塩化合物からなる群より選ばれる1種または2種以上を含む酸化剤溶液を調製する工程と、
前記砥粒分散液と前記酸化剤溶液とを混合する工程とを有することを特徴とする金属膜研磨用組成物の製造方法。
A method for producing a metal film polishing composition for producing a metal film polishing composition for polishing a tungsten film and a TEOS film,
An abrasive dispersion containing fumed silica that is abrasive grains and a pH adjuster, and an iodate, chlorate compound, and bromic acid that are oxidizing agents so that the pH after mixing is 6 to 8.5. Preparing an oxidizer solution containing one or more selected from the group consisting of salt compounds;
A method for producing a metal film polishing composition comprising the step of mixing the abrasive dispersion and the oxidant solution.
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