JP2004342751A - Cmp slurry, polishing method, and method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slurry which is capable of reducing both dishing and erosion and polishing a target surface as an object of polishing at a practical polishing speed. <P>SOLUTION: The CMP (chemical mechanical polishing) slurry contains composite particles including a composite resin component and an inorganic component and resin particles. The CMP slurry is characterised by having a viscosity of below 10 mPaS. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０１００】
表１に示されるように、複合型粒子および樹脂粒子のζ電位がいずれもマイナスの場合（Ｎｏ．１〜５，１０）、およびいずれもプラスの場合（Ｎｏ．７）には、スラリーの粘度は１ｍＰａＳである。同様に、樹脂粒子のζ電位が零の場合（Ｎｏ．８，９）のスラリーも、１ｍＰａＳと低粘度である。これらのスラリーを用いた場合には、１１０ｎｍ／ｍｉｎ以上の高い研磨速度でＷ膜を研磨することができた。いずれの場合も、研磨後の表面のディッシングは、１０ｎｍ以下に抑制されていた。
【０１０１】
樹脂粒子表面の官能基の種類を変更した場合、さらに、界面活性剤を添加した場合にも同様に高い研磨速度が得られた。複合型粒子における樹脂成分は、樹脂粒子の材料と必ずしも同一である必要はなく、異なる場合にも同等の効果が得られる。また、複合型粒子および樹脂粒子は、それぞれ２種以上を組み合わせて用いた場合にも、高い研磨速度が期待される。
【０１０２】
Ｎｏ．１〜１０のスラリーはｐＨが２．５程度であり、このようにｐＨが低い場合でも、本発明の実施形態にかかるスラリーは、十分に高い研磨速度を確保することができる。逆に、１０以上の高いｐＨにおいても、本発明の実施形態にかかるスラリーは同様の効果を発揮することが期待される。
【０１０３】
研磨粒子として、樹脂粒子または複合型粒子を単独で含有する従来のスラリーは、３〜７程度の狭いｐＨ範囲でしか使用することができなかった。これは、研磨粒子と研磨パッドとの相互作用を高めるために界面活性剤や有機化合物が添加されていたことによる。強酸や強アルカリの領域では、こうした添加剤が失活するために効果を得ることができなかった。
【０１０４】
本発明の実施形態においては、複合型粒子と樹脂粒子とを混合して研磨粒子として用いるために、研磨粒子と研磨パッドとの間に十分な相互作用を得ることができる。したがって、従来は不可能であった広いｐＨ範囲においても使用することが可能となった。
【０１０５】
表１に示されるように、ζ電位がプラスの複合型粒子と、ζ電位がマイナスの樹脂粒子との粒子混合物を含有する場合（Ｎｏ．６）には、スラリーの粘度は１２ｍＰａＳと非常に高い。このように高粘度のスラリーは、スラリー供給ノズル３７から研磨布３１上に滴下することが困難となり、ＣＭＰを行なうことができなかった。
【０１０６】
（実施形態２）
Ｃｕのダマシン配線形成プロセスにおいてＣｕ２ｎｄポリッシュの際には、Ｃｕ膜に加えて、例えばＴａＮ膜やＳｉＯ_２膜といった異種材料を平坦に研磨することになる。従来、こうした場合には、研磨速度比を１として非選択性の研磨が行なわれてきた。しかしながら、有機系絶縁膜の場合には、硬度や表面の疎水性といった物性的な影響により、前述の条件で研磨するとエロージョンが大きく生じてしまう。
【０１０７】
本発明の実施形態にかかるスラリーを用いることによって、研磨速度比を１以上として選択性の研磨を行なっても、低エロージョンでＣｕダマシン配線を形成することができる。しかも、研磨後の有機絶縁膜やＣｕ膜の表面には、スクラッチはほとんど生じることがない。
【０１０８】
図６は、Ｃｕ−ＣＭＰを示す工程断面図である。
【０１０９】
まず、図６（ａ）に示すように、素子（図示せず）が形成された半導体基板４０上に絶縁膜４１を堆積し、コンタクト４２を形成しておく。絶縁膜４１上には、低誘電率膜４３としてのＬＫＤ５１０９（ＪＳＲ製）を２００ｎｍ堆積し、さらに、キャップ膜４４としてのブラックダイヤモンド（ＡＭＡＴ製、以下ＢＤと称する）を１００ｎｍ、ＣＶＤ法により堆積する。低誘電率絶縁膜４３およびキャップ膜４４に溝４５をＲＩＥにより形成した後、全面にＴａＮ膜４６（２０ｎｍ）およびＣｕ膜４７（５００ｎｍ）を、スパッタリング法およびメッキにより堆積した。
【０１１０】
次に、Ｃｕ膜４７の不要部分を以下の条件でＣＭＰにより除去して、図６（ｂ）に示すようにＴａＮ膜４６を露出させた。
【０１１１】
スラリー：ＣＭＳ７３０３／７３０４（ＪＳＲ社）
流量：２５０ｃｃ／ｍｉｎ
研磨布：ＩＣ１０００（ロデール・ニッタ社）
荷重：３００ｇｆ／ｃｍ^２
キャリアおよびテーブルの回転数はいずれも１００ｒｐｍとして、１分間の研磨を行なった。この工程では、ＴａＮ膜４６で研磨を停止しているため、疎水性であるキャップ膜４４は露出していない。したがって、市販のスラリーを用いて研磨することができる。
【０１１２】
その後、タッチアップ工程により、図６（ｃ）に示すようＴａＮ膜４６の不要部分を除去した。この際のＣＭＰには、本発明の実施形態にかかるスラリーが用いられる。
【０１１３】
スラリーの調製に当たっては、平均粒子径（ｄ_１）が２００ｎｍの複合型粒子と、平均粒子径（ｄ_２）が１００ｎｍの樹脂粒子との粒子混合物を研磨粒子として準備した。複合型粒子と樹脂粒子との粒径比（ｄ_１／ｄ_２）は２である。複合型粒子は、樹脂成分としての平均粒子径１５０ｎｍのＰＭＭＡ粒子と、無機成分としての平均粒子径２５ｎｍのシリカ粒子とを含む。樹脂粒子はＰＭＭＡからなり、官能基としてのＣＯＯＨ基を表面に有する。複合型粒子および樹脂粒子は、前述と同様の手法により、同様の濃度の原液として準備した。
【０１１４】
複合型粒子の濃度が２．７ｗｔ％、樹脂粒子の濃度が０．３ｗｔ％となるように、前述の複合型粒子の原液と樹脂粒子の原液とを混合して、純水で希釈した。さらに、酸化剤としての過酸化水素水０．１ｗｔ％、酸化抑制剤としてのキノリン酸０．８ｗｔ％、および添加剤などを加え、ｐＨ調整剤としてのＫＯＨによりｐＨを１０に調整した。
【０１１５】
また、研磨粒子を、平均粒径の異なる２種類のコロイダルシリカに変更した以外は、前述と同様の処方により比較例のスラリーを調製した。具体的には、平均粒径４０ｎｍのコロイダルシリカ０．６ｗｔ％と、平均粒径２０ｎｍのコロイダルシリカ２．４ｗｔ％との混合物を研磨粒子として用いた。
【０１１６】
各スラリーを用いて前述と同様の条件で２分間の研磨を行なって、Ｃｕ膜４７、ＴａＮ膜４６およびキャップ膜４４の研磨速度を調べた。研磨時間は、キャップ膜４４としてのＢＤが５０ｎｍ研磨される時間に調整した。その結果、本発明の実施形態にかかるスラリーを用いた場合、Ｃｕ膜、ＴａＮ膜、およびキャップ膜の研磨速度は、それぞれ１００ｎｍ／ｍｉｎ、４５ｎｍ／ｍｉｎ、および２０ｎｍ／ｍｉｎであった。これに対し、比較例のスラリーを用いた場合には、Ｃｕ膜の研磨速度は７０ｎｍ／ｍｉｎであり、ＴａＮ膜およびキャップ膜の研磨速度は、いずれも６０ｎｍ／ｍｉｎであった。
【０１１７】
このように、比較例のスラリーを用いた場合には、キャップ膜４４の研磨速度が６０ｎｍ／ｍｉｎと大きいためにエロージョンが生じて、その一部が抜けてしまっていた。Ｃｕ膜とキャップ膜４４との段差は、Ｃｕ膜の方が飛び出した形状となり、エロージョンは１２０ｎｍであった。キャップ膜４４は、次工程で生じるダメージから絶縁膜４３を保護する必要があるため、破れることは極力避けなければならない。これに対して、本発明の実施形態にかかるスラリーを用いた場合には、エロージョンは２０ｎｍと低い値を示し、キャップ膜４４が破れることはなかった。有機材料からなる樹脂粒子が含有されているので、本発明の実施形態にかかるスラリーは、有機膜との間に適切な相互作用を生じることができる。
【０１１８】
また、研磨後のＣｕ膜４７表面におけるディッシングは２０ｎｍ以下に抑制された。さらに、研磨後のＣｕ膜４７上およびキャップ膜４４上の１ｃｍ^２におけるスクラッチは、比較例のスラリーを用いた場合には約１００００個であったのに対し、本発明の実施形態にかかるスラリーを用いた場合には、１００個以下に低減された。添加成分を最適化することによって、スクラッチをさらに低減することも可能である。
【０１１９】
（実施形態３）
本発明の実施形態にかかるスラリーは、ＳＴＩ（Ｓｈａｌｌｏｗ ｔｒｅｎｃｈ ｉｓｏｌａｔｉｏｎ）の形成に適用することも可能である。図７は、ＳＴＩの形成プロセスを示す工程断面図である。
【０１２０】
まず、図７（ａ）に示すように、ＣＭＰストッパー膜５１が設けられた半導体基板５０に溝を形成し、その上に絶縁膜５２を堆積する。ここで、ＣＭＰストッパー膜５１としてはＳｉＮが用いられ、絶縁膜５２としては、例えば、有機ＳＯＧなどの塗布型絶縁膜を用いることができる。
【０１２１】
次いで、絶縁膜５２の不要部分を、本発明の実施形態にかかるスラリーを用いたＣＭＰにより除去して、図７（ｂ）に示すようにＣＭＰストッパー膜５１表面を露出した。スラリーは、平均粒子径（ｄ_１）が２００ｎｍの複合型粒子と、平均粒子径（ｄ_２）が１００ｎｍの樹脂粒子との粒子混合物を研磨粒子として用いて調製した。複合型粒子と樹脂粒子との粒径比（ｄ_１／ｄ_２）は２である。複合型粒子は、樹脂成分としての平均粒子径２００ｎｍのＰＳＴ粒子と、無機成分としての平均粒子径４０ｎｍのシリカ粒子とを含む。こうした複合型粒子の合成に当たっては、まず、スチレン９２部、メタクリル酸４部、ヒドロキシエチルアクリレート４部、ラウリル硫酸アンモニウム０．１部、過硫酸アンモニウム０．５部、およびイオン交換水４００部を、容量２リットルのフラスコに収容した。この混合物を、窒素ガス雰囲気下、攪拌しながら７０℃に昇温し、６時間重合させた。これによって、カルボキシル基を有するＰＳＴ粒子を２０ｗｔ％の濃度で含有する樹脂粒子の原液を得た。なお、ＰＳＴ粒子の合成に当たっては、架橋剤として、ジビニルベンゼン（純度；５５％）１部を添加した。ＣＯＯＨ以外の官能基を形成する場合には、ピリジン環化合物（アミノ基）、スルホン酸塩（スルホン基）などを用いることができる。
【０１２２】
複合化に当たっては、まず、ＰＳＴ粒子を１０重量％含む水分散体１００部を、容量２リットルのフラスコに収容し、メチルトリメトキシシラン１部を添加した。この混合物を、４０℃で２時間攪拌した。その後、硝酸を添加してｐＨを２に調整し、樹脂成分の水分散体を得た。また、水中にコロイダルシリカ（日産化学株式会社製、商品名「スノーテックスＯ」）を１０重量％の濃度で分散させ、水酸化カリウムによりｐＨを８に調整して、無機成分の水分散体を得た。その後、樹脂成分の水分散体１００部に無機成分の水分散体５０部を、２時間かけて徐々に添加し、混合した。さらに、２時間攪拌して、重合体粒子にシリカ粒子が付着した予備粒子を含む水分散体を得た。次いで、この水分散体にビニルトリエトキシシラン２部を添加し、１時間攪拌した後、ＴＥＯＳ１部を添加して６０℃に昇温した。その後、３時間攪拌を継続し、冷却することによって、複合型粒子を１０ｗｔ％の濃度で含む複合型粒子の原液を調製した。
【０１２３】
複合型粒子の濃度が１８ｗｔ％、樹脂粒子の濃度が２ｗｔ％となるように、前述の複合型粒子の原液の濃縮液と樹脂粒子の原液とを混合し、純水で希釈した。なお、ここでは、複合型粒子の原液の上澄み液を粒子沈降法により除去して、複合型粒子の濃度を２０ｗｔ％とした濃縮液と、上述した２０ｗｔ％の濃度で架橋ＰＳＴ粒子を含有する樹脂粒子の原液を用いた。さらに、ｐＨ調整剤としてのＫＯＨによりｐＨを１１に調整した。
【０１２４】
得られたスラリーを用いて、以下の条件で絶縁膜５２を研磨した。
【０１２５】
スラリー流量：３００ｃｃ／ｍｉｎ
研磨布：ＩＣ１０００（ロデール・ニッタ社製）
研磨荷重：３００ｇｆ／ｃｍ^２
トップリングおよびテーブルの回転数はいずれも１００ｒｐｍとして、３分間の研磨を行なった。
【０１２６】
ＣＭＰストッパー膜５１の材質として用いられるＣやＳｉＮは、多くの場合、疎水性を有しており、ζ電位が等電点である。このため、スクラッチを生じやすい環境にある。
【０１２７】
本実施形態にかかるスラリーを用いることによって、研磨後のウェハー表面におけるスクラッチは２個にとどまり、エロージョンは３０ｎｍ以下に抑制された。こうして、スクラッチを生じ易いＣＭＰストッパー膜上の絶縁膜をＣＭＰする際にも効果を確認することができた。
【０１２８】
【発明の効果】
上述したように、本発明の態様によれば、ディッシングやエロージョンを低減するとともに、実用的な研磨速度で被研磨面を研磨可能なスラリーが提供される。本発明の他の態様によれば、ディッシングやエロージョンを低減するとともに、実用的な研磨速度で被研磨面を研磨する方法が提供される。本発明の他の態様によれば、高い信頼性を有する半導体装置の製造方法が提供される。
【０１２９】
本発明によれば、例えば、次世代で要求されるデザインルール０．１μｍ以下の配線を有する高性能・高速な半導体装置を製造することが可能となり、その工業的価値は絶大である。
【図面の簡単な説明】
【図１】複合型粒子および樹脂粒子の断面の状態を模式的に示す概略図。
【図２】トップリングの断面図。
【図３】本発明の一実施形態にかかる半導体装置の製造方法を表わす工程断面図。
【図４】ＣＭＰの状態を示す概略図。
【図５】Ｗ膜の研磨速度とスラリー中の樹脂粒子の含有量との関係を示す図。
【図６】本発明の他の実施形態にかかる半導体装置の製造方法を表わす工程断面図。
【図７】本発明の他の実施形態にかかる半導体装置の製造方法を表わす工程断面図。
【符号の説明】
１０…複合型粒子，１１…樹脂成分，１２…無機成分，１３…樹脂粒子，２０…半導体基板，２１…絶縁膜，２２…ホール，２３…ＴｉＮ膜，２４…Ｗ膜，３０…ターンテーブル，３１…研磨布，３２…半導体基板，３３…トップリング，３４…水供給ノズル，３５…スラリー供給ノズル，３６…ドレッサー，３７…スラリー，４０…半導体基板，４１…絶縁膜，４２…コンタクト，４３…低誘電率膜，４４…キャップ膜，４５…溝，４６…ＴａＮ膜，４７…Ｃｕ膜，５０…半導体基板，５１…ＣＭＰストッパー膜，５２…絶縁膜，６０…半導体基板，６１…リテーナリング，６２…研磨布，６３…筐体，６４…エア供給管，６５…チャッキングプレート，６６…エアバック，６７…トップリング，６８…トップリング、６９…バッキングフィルム。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a slurry used for CMP (Chemical Mechanical Polishing), a polishing method using the slurry, and a method for manufacturing a semiconductor device.
[0002]
[Prior art]
In the next-generation high-performance LSI, high integration of elements is indispensable, and design rules for damascene wiring formed by CMP are becoming stricter with a wiring width of 0.07 to 30 μm and a film thickness of 100 nm.
[0003]
In the case of forming a damascene wiring having a thickness of 100 nm, in conventional CMP, abrasive particles released from the polishing cloth during polishing become loose particles and are pushed into the surface to be polished, resulting in dishing of about 80 nm. In this case, most of the wiring material (Cu, Al, W, etc.) to be buried in the groove is removed. When excessive dishing occurs, the wiring resistance increases, and the performance of the semiconductor device decreases. In addition, there is a risk of disconnection during operation, which is a concern in terms of reliability. For this reason, dishing is required to be suppressed to 20 nm or less.
[0004]
Conventionally, it is considered that such a demand can be met by reducing free particles during polishing, and a method using a fixed abrasive type CMP pad (for example, a 3M company fixed abrasive type pad) with a small amount of free particles is used. Is being considered. Although dishing is suppressed to 20 nm or less by using such a pad, there remain problems such as processing efficiency, price, processed surface quality, and stability.
[0005]
In addition, a method of increasing the interaction between the polishing particles and the polishing pad has been proposed (for example, see Patent Document 1). For example, a slurry using composite particles as abrasive particles and an organic compound such as a surfactant and an organic acid is used, but the polishing power is poor and the method is not practical.
[0006]
Further, an extremely high-viscosity slurry containing two types of resin particles as abrasive particles has been proposed (for example, see Patent Document 2). Such a slurry has an increased viscosity applied to polishing using a brush, and cannot be dropped by a slurry supply pipe and subjected to CMP by a normal method.
[0007]
[Patent Document 1]
JP 2001-152133 A
[0008]
[Patent Document 2]
JP 2003-109919 A
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a slurry capable of reducing dishing and erosion and polishing a surface to be polished at a practical polishing rate.
[0010]
Another object of the present invention is to provide a method for polishing a surface to be polished at a practical polishing rate while reducing dishing and erosion.
[0011]
Another object of the present invention is to provide a method for manufacturing a semiconductor device having high reliability.
[0012]
[Means for Solving the Problems]
A slurry for CMP according to one embodiment of the present invention is characterized by containing composite particles containing a composite resin component and an inorganic component, and resin particles, and having a viscosity of less than 10 mPaS.
[0013]
The polishing method according to one embodiment of the present invention includes a step of rotating and contacting a semiconductor substrate having a surface to be polished with a polishing cloth stuck on a turntable, and the above-mentioned CMP for polishing on the polishing cloth. The method further comprises a step of polishing the surface to be polished by dropping a slurry.
[0014]
A method for manufacturing a semiconductor device according to one embodiment of the present invention includes a step of forming an insulating film on a semiconductor substrate, a step of forming a recess in the insulating film, and a step of forming a conductive layer inside the recess and on the insulating film. Depositing a material to form a layer having conductivity, and removing the conductive material deposited on the insulating film to expose the surface of the insulating film, thereby forming the conductive material. And removing the conductive material deposited on the insulating film by CMP using the above-mentioned slurry.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0016]
In order to efficiently apply the slurry supplied on the polishing cloth to the surface to be polished and perform polishing while reducing dishing and erosion, the present inventors polish a particle mixture of composite type particles and resin particles. It has been found that it is effective to use the particles as particles and to regulate the viscosity to less than 10 mPaS.
[0017]
FIG. 1 is a schematic diagram of composite particles and resin particles. The composite particles 10 are composed of polymer particles as a resin component 11 and an inorganic component 12 composited with the polymer particles. Complexation refers to chemical or non-chemical association. The inorganic component 12 can be, for example, a silicon compound part or a metal compound part. The inorganic component 12 may not only bind to the surface of the resin component 11 as shown in the figure, but may be incorporated inside. On the other hand, the resin particles 13 preferably have a functional group such as COOH on the surface.
[0018]
As the composite particles 10, for example, those described in JP-A-2000-204352 can be used, and can be generally synthesized by the following method. First, a silane coupling agent or the like is bonded to divinylbenzene polymer particles or the like serving as the resin component 11, and a specific silane alkoxide and colloidal silica are reacted with the silane coupling agent. In this way, a silicon compound part having a polysiloxane structure or the like as the inorganic component 12 is formed inside and on the surface of the polymer particles. The silicon compound part and the like can also be formed without using a silane coupling agent or the like. It is preferable that the inorganic component is bonded to the polymer particles via a silane coupling agent or the like or directly. Further, a compound such as aluminum, titanium or zirconium can be used as the inorganic component 12 to obtain the composite type particles 10 having the same configuration.
[0019]
Hereinafter, the polymer particles as the resin component 11 in the composite particles 10 will be described in detail.
[0020]
The polymer particles are particles made of a polymer obtained by polymerizing various monomers. Examples of the monomer include unsaturated aromatic compounds such as styrene, α-methylstyrene, halogenated styrene and divinylbenzene, unsaturated esters such as vinyl acetate and vinyl propionate, and unsaturated nitriles such as acrylonitrile. Can be used. Further, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl Acrylic esters such as acrylate, acrylic acrylate and allyl methacrylate or methacrylic esters can also be used.
[0021]
Also, butadiene, isoprene, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, and the like can be used. These monomers may be used alone or in combination of two or more.
[0022]
The polymer particles can be obtained by polymerizing the above-described monomers by various methods such as emulsion polymerization, suspension polymerization, and dispersion polymerization. By controlling the polymerization conditions, the particle size of the polymer particles can be arbitrarily adjusted. Further, a polymer such as a lump may be pulverized into polymer particles having a desired particle size. In particular, when polymer particles having high strength and the like and excellent heat resistance are required, a cross-linked structure can be introduced into the molecule by using a polyfunctional monomer when producing the polymer particles. The crosslinked structure can be introduced by a method such as chemical crosslinking or electron beam crosslinking during the production of the polymer particles or after the production of the polymer particles.
[0023]
Although the shape of the polymer particles is not particularly limited, it is desired that the shape is more spherical. The average particle diameter is preferably 0.03 to 100 μm, more preferably 0.05 to 20 μm, and most preferably 0.05 to 1.0 μm as a sphere equivalent diameter. When the average particle size is less than 0.03 μm, it is difficult to obtain sufficient polishing performance because the particle size is too small. On the other hand, if the average particle size exceeds 100 μm, the dispersibility of the composite particles may be deteriorated, and the storage stability may be significantly reduced.
[0024]
It is preferable to introduce a functional group such as a hydroxyl group, an epoxy group, and a carboxyl group into the obtained polymer particles. In this case, the inorganic component can be directly bonded to the polymer particles without using a linking compound such as a silane coupling agent. When a silane coupling agent or the like having a functional group capable of reacting with the functional group introduced into the polymer particles is used in combination, the bonding between the inorganic component and the polymer particles is further promoted, and a composite type having further excellent performance is provided. Particles are obtained.
[0025]
Further, as the polymer particles, particles composed of various polymers such as polyamide, polyester, polycarbonate, and polyolefin can also be used. In these polymer particles, a functional group can be introduced in the same manner as described above, and further, a crosslinked structure can be introduced into the particles.
[0026]
Although various polymers can be used as described above, polymethyl methacrylate (PMMA) and polystyrene (PST) are particularly preferable because they are easily available industrially.
[0027]
Next, the silicon compound part and the metal compound part as the inorganic component 12 will be described in detail. At least a part of the inorganic component is directly or indirectly bonded to the polymer particles, but is preferably chemically bonded. Thereby, at the time of polishing, there is no problem that the inorganic component easily falls off from the polymer particles and remains on the surface to be polished. Examples of the chemical bond include an ionic bond and a coordination bond, and a covalent bond is preferable because the bond is more strongly bonded. The inorganic component 12 may be bonded to the polymer particles by a non-chemical bond such as a hydrogen bond, a surface charge bond, an entanglement bond, and an anchor effect bond.
[0028]
As shown in FIG. 1, in order to bond to the surface of the resin component 11, the inorganic component needs to be smaller than the polymer particles as the resin component. It is calculated by calculation that if the longest diameter of the inorganic component is about 1/4 or less of the particle diameter of the polymer particles, it can be uniformly bonded. However, in order to secure the polishing force, it is desired that the longest diameter of the inorganic component is 10 nm or more.
[0029]
The silicon compound part as an inorganic component can be constituted by at least one of a siloxane bond-containing part and a silica particle part. Further, the metal compound part can be composed of at least one selected from the group consisting of a metalloxane bond-containing part, an alumina particle part, a titania particle part, and a zirconia particle part.
[0030]
Such an inorganic component may be formed inside the polymer particles and over the entire surface thereof, or may be formed on a part thereof. The siloxane bond-containing portion and the metalloxane bond-containing portion may be composed of a single molecule, but preferably have a chain structure of two or more molecules. In the case of a chain structure, it may be linear, but a three-dimensional structure is more preferable.
[0031]
The inorganic component can be bonded to the polymer particles directly or via a linking compound such as a silane coupling agent. Examples of the linking compound include a silane coupling agent, an aluminum-based coupling agent, a titanium-based coupling agent, and a zirconium-based coupling agent, with the silane coupling agent being particularly preferred. Examples of the silane coupling agent include the following (a), (b) and (c).
[0032]
(A) vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxy Silane and the like.
[0033]
(B) γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and the like.
[0034]
(C) N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane and the like.
[0035]
As the silane coupling agent, those having a functional group that can easily react with a functional group introduced into the polymer particles are preferable. For example, in the case of polymer particles having a carboxyl group introduced on the surface, the silane coupling agents (b) and (c) having an epoxy group and an amino group are preferred. Among them, γ-glycidoxypropyltrimethoxysilane and N-β (aminoethyl) γ-aminopropyltrimethoxysilane are particularly preferred.
[0036]
Examples of the aluminum-based coupling agent include acetoalkoxyaluminum diisopropylate. Examples of the titanium-based coupling agent include isopropyl triisostearoyl titanate and isopropyl tridecylbenzenesulfonyl titanate. These various coupling agents may be used alone or in combination of two or more. Also, different types of coupling agents can be used in combination.
[0037]
The amount of the coupling agent to be used is preferably 0.1 to 50 mol per 1 mol of the functional group introduced into the polymer particles. This amount is more preferably 0.5 to 30 mol, and most preferably 1.0 to 20 mol. When the amount of the coupling agent used is less than 0.1 mol, the inorganic component is not sufficiently firmly bonded to the polymer particles, and easily falls off from the polymer particles during polishing. On the other hand, if the amount used exceeds 50 mol, the condensation reaction of the coupling agent molecules proceeds, and an unintended polymer may be generated. In this case, the binding of the inorganic component to the polymer particles may be hindered.
[0038]
When the coupling agent is chemically bonded to the polymer particles, the reaction can be promoted by using a catalyst such as an acid and a base. To promote the reaction, the temperature of the reaction system may be raised.
[0039]
Further, a compound represented by the following general formula (1) can also be used as a raw material of an inorganic component.
[0040]
R_nM (OR ')_z-n        (1)
Here, R is a monovalent organic group having 1 to 8 carbon atoms, specifically, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, Examples include an alkyl group such as a tert-butyl group and an n-pentyl group, a phenyl group, a vinyl group, and a glycidpropyl group. R ′ is an alkyl group having 1 to 5 carbon atoms, an acyl group having 2 to 6 carbon atoms or an aryl group having 6 to 9 carbon atoms, specifically, a methyl group, an ethyl group, an n-propyl group and an iso group. -Propyl, acetyl, propionyl, butyryl, valeryl and caproyl, phenyl and tolyl. When two or more R and R 'are present, they may be the same or different.
[0041]
M is Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, Sb, Ta, W, Pb or Ce. Particularly, Al, Si, Ti and Zr are preferable.
[0042]
Z is the valence of M, and n is an integer of 0 to (z-1).
[0043]
Here, a compound containing Al, Si, Ti or Zr as M will be described. Examples of the compound in which M is Si include tetramethoxysilane, tetraethoxysilane (TEOS), tetra-iso-propoxysilane, tetra-tert-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and the like. These compounds form a silicon compound portion as an inorganic component. Further, examples include aluminum ethoxide in which M is Al, titanium (IV) ethoxide in which M is Ti, and zirconium-tert-butoxide in which M is Zr. Such a compound forms a metalloxane bond-containing portion, an alumina particle portion, a titania particle portion, or a zirconia particle portion as an inorganic component.
[0044]
The compounds as described above may be used alone or in combination of two or more. Further, a compound in which M is Si, Al, Ti or Zr can be used in combination. It is preferable that (z−n) in the general formula (1) be 2 or more, since a denser siloxane bond-containing portion or metalloxane bond-containing portion is formed.
[0045]
Not only the compound represented by the general formula (1) but also at least one of the hydrolyzate and the partial condensate may be used. The compound represented by the general formula (1) is hydrolyzed or partially condensed without any particular operation. However, if necessary, the compound can be hydrolyzed or partially condensed at a required ratio in advance.
[0046]
The amount of these compounds used is SiO₂, Al₂O₃, TiO₂Or ZrO₂In terms of conversion, the weight ratio is preferably set to 0.001 to 100 with respect to the polymer particles. This weight ratio is more preferably from 0.005 to 50, and most preferably from 0.01 to 10. When the weight ratio is less than 0.001, the inorganic component is not sufficiently formed inside and on the surface of the polymer particles, and the polishing performance may be reduced. On the other hand, even if the weight ratio is increased beyond 100, remarkable improvement in polishing performance cannot be expected.
[0047]
Further, at least one selected from the group consisting of colloidal silica, colloidal alumina, colloidal titania, and colloidal zirconia may be used as a raw material of the inorganic component. Such a colloidal component can be prepared by dispersing silica, alumina, titania or zirconia in the form of fine particles having an average particle size of 5 to 500 nm in a dispersion medium such as water. Fine particles can be obtained by a method of growing particles in an aqueous alkaline solution, a gas phase method, or the like.
[0048]
These fine particles may be bonded to the polymer particles via a siloxane bond-containing portion or a metalloxane bond-containing portion as described above. Alternatively, each particle portion can be formed by bonding to a polymer particle, a siloxane bond-containing portion, a metalloxane bond-containing portion, or the like by a hydroxyl group or the like introduced into the fine particles. The amount of colloid used is SiO₂, Al₂O₃, TiO₂Or ZrO₂It is preferable that the weight ratio is 0.001 to 100 based on the polymer particles. This weight ratio is more preferably 0.01 to 50, most preferably 0.1 to 10. When the weight ratio is less than 0.001, it is difficult to sufficiently form an inorganic component. On the other hand, if it exceeds 100, no further improvement in polishing performance is observed.
[0049]
The reaction of the above components with the polymer particles can be carried out in a dispersion system using various organic solvents such as water or alcohol as a dispersion medium. The dispersion medium may be used alone or as a mixture of two or more. In the case of a dispersion medium containing water, hydrophilic functional groups such as a hydroxyl group, an epoxy group, and a carboxyl group should be introduced into the polymer particles in order to stably and uniformly disperse the polymer particles in the dispersion system. Is preferred. By introducing these functional groups, the inorganic component as described above can be more easily bonded to the polymer particles.
[0050]
Examples of the alcohol that can be used as a dispersion medium include lower saturated aliphatic alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and tert-butanol. The alcohol may be used alone or in combination of two or more. Examples of the organic solvent other than alcohol include methyl ethyl ketone and dimethylformamide. Such an organic solvent, water and alcohol may be mixed and used at a predetermined ratio.
[0051]
In the reaction at this time, the content of the polymer particles in the dispersion medium is preferably 0.001 to 70% by weight. It is more preferably 0.01 to 50% by weight, most preferably 0.1 to 25% by weight. If the amount is less than 0.001% by weight, it is difficult to obtain composite particles with a sufficient yield. On the other hand, when the content exceeds 70% by weight, the dispersion stability of the polymer particles is reduced, and a problem occurs in that a gel is easily generated at the stage of complexing.
[0052]
The reaction for binding the inorganic component can be promoted by heating or adding a catalyst. When heating, the temperature of the reaction system is preferably set to 40 to 100 ° C. As the catalyst, for example, an acid, a base, an aluminum compound, a tin compound and the like can be used. In particular, an acid catalyst and an aluminum catalyst are preferable since they have a large effect of accelerating the reaction.
[0053]
Also, composite particles thermally bonded by the mechanofusion phenomenon can be used (Particle Design Engineering, P97, Sangyo Tosho Co., Ltd.).
[0054]
Various composite particles as described above can be used.
[0055]
On the other hand, as the resin particles 13, for example, those described in JP-A-2000-204275 can be used. Specifically, the resin particles 13 can be made of the same material as the resin component in the above-described composite particles, and the shape is preferably spherical. The spherical shape also means a substantially spherical shape having no acute angle portion, and does not necessarily have to be a true sphere.
[0056]
The resin particles preferably have a crosslinked structure, and can be synthesized, for example, by copolymerizing a crosslinkable monomer with another monomer. In the copolymerization, the proportion of the crosslinkable monomer is preferably 5 to 80% by weight, more preferably 5 to 60% by weight, and most preferably 7 to 60% by weight. When the crosslinkable monomer is less than 5% by weight, it becomes difficult to obtain resin particles having sufficient hardness. On the other hand, if it exceeds 80% by weight, the resin particles may become brittle, though the hardness is increased. By having a crosslinked structure, the hardness and strength of the resin particles can be increased.
[0057]
The resin particles preferably have a hydrophilic group as a functional group on the surface. The polarity of the ζ potential on the surface of the resin particles can be controlled by the hydrophilic group, and the properties such as antistatic property, heat resistance and discoloration resistance can be enhanced in addition to hardness and strength. Moreover, the resin particles having a hydrophilic group on the surface are also excellent in compatibility with a compound having a polar group.
[0058]
Resin particles having a hydrophilic group include hydrophilic groups such as hydroxyl groups, carboxyl groups and salts thereof, acid anhydride groups, sulfonic acid groups and salts thereof, phosphoric acid groups and salts thereof, amino groups and salts thereof, and the like. It can be formed by introducing 0.1 mmol or more, preferably 1 to 100 mmol, per 100 g.
[0059]
A surfactant having a predetermined hydrophilic group may be separately added so that the hydrophilic group is bonded to the surface of the resin particles in the slurry. As the surfactant, any of a cationic surfactant, an anionic surfactant, a nonionic surfactant and the like can be used. Examples of the cationic surfactant include an aliphatic amine salt and an aliphatic ammonium salt. Examples of the anionic surfactant include fatty acid soap, carboxylate such as alkyl ether carboxylate, sulfonate such as alkylbenzene sulfonate, alkylnaphthalene sulfonate, α-olefin sulfonate, and higher alcohol sulfate. Examples thereof include sulfate salts such as ester salts, alkyl ether sulfates and polyoxyethylene alkylphenyl ethers, and phosphate ester salts such as alkyl phosphate esters. Examples of the nonionic surfactant include ether type such as polyoxyethylene alkyl ether, ether ester type such as polyoxyethylene ether of glycerin ester, and ester type such as polyethylene glycol fatty acid ester, glycerin ester, and sorbitan ester. Can be mentioned.
[0060]
The slurry according to the embodiment of the present invention can be prepared by combining the composite particles and the resin particles as described above so that the polarities thereof have a predetermined relationship, and dispersing the particles in water. Specifically, the composite particles and the resin particles are combined so that the surfaces have the same polarity.
[0061]
The ζ potential can be measured, for example, by a laser Doppler zeta potential measuring device (manufactured by BROOKHAVEN INSTRUMENTS, product name “Zetaplus”). In measuring the potential, the inorganic component is dispersed in water or the like to prepare a dispersion having a predetermined pH. The zeta potential of the inorganic component at an arbitrary pH can be obtained by measuring the dispersion with the above-mentioned zeta potential measuring device. In order to measure the zeta potential of the functional group, the target functional group may be bonded to the surface of the resin particles, dispersed in water or the like, and similarly measured as a solution having a predetermined pH.
[0062]
The polarity of the composite particles depends on the inorganic component. For example, the zeta potential of silica is zero (isoelectric point) at pH 1.4, and becomes negative when the pH exceeds 1.4. The zeta potential of alumina is zero at pH 7 and positive below pH 7. On the other hand, the ζ potential of the resin particles is determined according to the functional groups present on the surface. For example, in the case of a carboxyl group (COOH), there is no isoelectric point, and the ζ potential is negative in the entire pH range (0.5 to 14). Amino group (NH₂) Potential is positive in the whole pH range.
[0063]
Alternatively, one of the composite particles and the resin particles may have an isoelectric point. The isoelectric point means that the ζ potential measured by the aforementioned zeta potential measuring device is within the range of 0 ± 5 mV. ζ Based on the pH at which the potential becomes 0, the potential on the particle surface is unstable even when the pH is within a range of ± 1. Therefore, such a range can be treated similarly to the isoelectric point. For example, a sulfonic acid group (SO₃The ζ potential of the polystyrene particles having H) is almost zero near pH2. That is, the composite particles and the resin particles are used in combination such that the surfaces do not have opposite polarities.
[0064]
In a slurry containing a particle mixture of composite particles and resin particles having opposite polarities as abrasive particles, the particles are electrically strongly attracted to each other to cause agglomeration, so that the viscosity of the slurry is extremely high at 10 mPaS or more. The slurry having such a high viscosity cannot be dropped on the polishing pad to perform the CMP of the surface to be polished. The currently used slurry supply system is a liquid circulation type using a pump, and when a high-viscosity slurry is used, clogging of the slurry occurs. Further, since the slurry having a high viscosity has poor storage stability, it is difficult for the slurry to easily settle and be re-dispersed.
[0065]
In order to limit the viscosity of the slurry to less than 10 mPaS, composite particles and resin particles having the same polarity are used. Even when one of the composite particles and the resin particles has an isoelectric point, the viscosity of the slurry is limited to less than 10 mPaS.
[0066]
In any case, the particle diameter of the resin particles is preferably larger than the longest diameter of the inorganic component in the composite particles. Specifically, it is desired that the particle size of the resin particles be at least twice the longest diameter of the inorganic component. As described above, in the composite particles, it is desired that the inorganic component is about １ ／ or less of the resin component. The particle size of the composite particles is preferably at least twice the particle size of the resin particles. Further, it is desirable that the resin particles be at least larger than the inorganic component so that the resin particles can be substituted for the resin component of the composite particles when the composite particles are deformed or broken by the stress of CMP. Taking these into consideration, it is desired that the particle size of the resin particles be at least twice as large as the inorganic component in the composite particles. However, in order to secure the polishing force, the longest diameter of the inorganic component is preferably 10 nm or more, and in consideration of the interaction with the polishing pad, the particle diameter of the resin particles is particularly limited to about 300 nm. preferable.
[0067]
In order to ensure a higher polishing rate, the average particle diameter d of the composite particles is₁And the average particle diameter d of the resin particles₂And the particle size ratio (d₁/ D₂) Is preferably 2 or more. By controlling the particle size ratio, a desired polishing rate can be obtained. However, in order to sufficiently secure the effect of mixing particles, the upper limit of the particle size ratio is limited to about 10. This is considered to be because when the resin particles are too small relative to the composite type particles, the state approaches a state where a surfactant having a small volume is added.
[0068]
The average particle size of the resin particles is preferably 0.05 to 1 μm. If it is less than 0.05 μm, it will be difficult to obtain a sphere. On the other hand, if it exceeds 1 μm, the particle size ratio (d₁/ D₂) Is 2 or more, the average particle diameter of the composite particles exceeds 2 μm. In this case, there is a possibility that the polishing power becomes insufficient due to the decrease in the particle surface area. The average particle size of the resin particles is more preferably 0.1 to 0.5 μm, and most preferably 0.1 to 0.3 μm. The average particle diameter of the composite particles and the resin particles can be obtained by TEM observation.
[0069]
Further, the ratio of the resin particles in the particle mixture of the composite particles and the resin particles is preferably in the range of 10 wt% or more and 90 wt% or less. When a particle mixture containing resin particles at such a ratio is used, a particularly high polishing rate can be obtained. For example, in the case of a W film, a high polishing rate of 100 nm / min or more can be secured.
[0070]
The total particle concentration of the particle mixture of the composite particles and the resin particles is preferably from 0.1 wt% to 40 wt% in the slurry. If the amount is less than 0.1 wt%, it is difficult to obtain a sufficient polishing effect. On the other hand, if it exceeds 40 wt%, the particles may aggregate. The total particle concentration is more preferably 0.5 wt% or more and 30 wt% or less in the slurry.
[0071]
If necessary, various additives such as an oxidizing agent and a pH adjuster can be added to prepare the slurry according to the embodiment of the present invention.
[0072]
Since the slurry according to the embodiment of the present invention contains a particle mixture of composite particles and resin particles as abrasive particles, these particles form a close-packed structure on the polishing cloth during polishing. . As a result, appropriate clogging occurs, and the particles can be fixed to the surface of the polishing pad to reduce free particles. As a result, it has become possible to perform polishing at a sufficiently high polishing rate while suppressing dishing. Moreover, since the surfaces of the composite particles and the resin particles have the same polarity or one of them has an isoelectric point, the viscosity of the slurry is sufficiently reduced.
[0073]
The inorganic components in the composite particles are firmly bound without coming off from the polymer particles as resin components even when subjected to polishing stress, and one resin component can be deformed or broken by receiving polishing stress. For this reason, during polishing, the inorganic component having abrasive power is bonded to the surface of the broken resin component, resulting in composite particles having a reduced diameter. The composite particles having such a reduced diameter are uniformly mixed with the resin particles.
[0074]
The resin particles are hydrophobic, and the polishing cloth surface is also hydrophobic. Therefore, the resin particles are adsorbed on the polishing cloth surface while entraining the composite type particles having a reduced diameter. As a result, it has become possible to perform polishing while reducing free particles.
[0075]
When the resin component and the inorganic component in the composite particles according to the embodiment of the present invention are used together with the resin particles as separate components, the above-described effects cannot be obtained. In this case, the particles are fixed so that the resin particles and the inorganic component are embedded in the gaps between the resin components. The polishing does not proceed because the inorganic component having abrasive power is not sufficiently present on the surface.
[0076]
When the composite particles are replaced with inorganic particles having the same particle size, the particle size of the inorganic particles having abrasive power is too large with respect to the resin particles. The particle size of the inorganic component is required to be 100 nm or less in order to perform fine polishing, and it is preferably 50 nm or less in order to sufficiently suppress dishing. When inorganic particles equivalent to the composite particles are contained, it becomes difficult to suppress dishing, and the object cannot be achieved.
[0077]
By using the slurry according to the embodiment of the present invention, it is possible to solve all the problems of the conventional fixed abrasive type pad such as processing efficiency, price, processed surface quality, and stability.
[0078]
By properly selecting the top ring that holds the semiconductor substrate, the abrasive particles can be more effectively fixed to the polishing pad, and the effect of the slurry according to the embodiment of the present invention can be further enhanced.
[0079]
FIG. 2 is a sectional view showing a schematic structure of an example of a top ring that can be used.
[0080]
The top ring 67 shown in FIG. 2A includes a housing 63 provided with an air supply pipe 64, a retainer ring 61, a chucking plate 65, and an airbag 66. The polished surface of the semiconductor substrate 60 held by the top ring 67 having such a structure is substantially the same as the end surface of the retainer ring 61. The semiconductor substrate 60 may be held so that the surface to be polished is positioned about 0.2 mm above the end face of the retainer ring 61.
[0081]
Therefore, the retainer ring 61 is pressed into the polishing pad 62 at a pressure similar to that of the semiconductor substrate 60. In some cases, the retainer ring 61 is pressed into the polishing pad 62 at a pressure higher than the semiconductor substrate 60. First, the slurry (not shown) supplied on the polishing cloth 62 is pushed into the polishing cloth 62 by the retainer ring 61 to fix the abrasive particles. Thereafter, since the slurry is supplied to the surface to be polished of the semiconductor substrate 60, the polishing is performed in a state where the free particles are reduced.
[0082]
On the other hand, when the top ring 68 as shown in FIG. 2B is used, the abrasive particles cannot be fixed to the polishing pad 62 prior to polishing the surface to be polished. That is, since the polished surface of the semiconductor substrate 60 held on the top ring 68 via the backing film 69 protrudes from the end surface of the retainer ring 61, the slurry (not shown) supplied on the polishing pad 62 is The semiconductor substrate 60 is supplied directly to the surface to be polished. Therefore, the abrasive particles are fixed to the polishing pad 62 by the semiconductor substrate 60, and the fixing of the abrasive particles and the polishing are performed simultaneously.
[0083]
Since the slurry according to the embodiment of the present invention contains the composite type particles and the resin particles, it is possible to reduce the free particles even when the immobilization and polishing of the particles are performed simultaneously. is there. However, in order to further enhance the effect of immobilizing particles, it is particularly preferable to use in combination with the top ring having the structure shown in FIG.
[0084]
(Embodiment 1)
First, 94 parts of methyl methacrylate (hereinafter, "part" means "part by weight"), 1 part of methacrylic acid, 5 parts of hydroxymethyl methacrylate, 0.03 part of ammonium lauryl sulfate, 0.6 part of ammonium persulfate Parts and 400 parts of ion-exchanged water were placed in a flask having a capacity of 2 liters. The mixture was heated to 70 ° C. while stirring under a nitrogen gas atmosphere, and polymerized for 6 hours. Thus, a stock solution of resin particles containing PMMA particles having a carboxyl group on the surface and having an average particle diameter of 200 nm at a concentration of 20 wt% was obtained.
[0085]
On the other hand, composite particles were prepared by bonding PMMA particles as a resin component to silica particles as an inorganic component. As PMMA particles, those synthesized by the above-described method were used. The particle diameter of the silica particles was set to 15 nm, and the average particle diameter (d) of the entire composite particles was changed by changing the average particle diameter of the PMMA particles.₁) Was changed. Specifically, composite particles having five average particle diameters of 100 nm, 200 nm, 300 nm, 400 nm, and 1000 nm were prepared.
[0086]
In the compounding, first, 100 parts of an aqueous dispersion containing 10% by weight of PMMA particles was placed in a flask having a capacity of 2 liters, and 1 part of methyltrimethoxysilane was added. The mixture was stirred at 40 ° C. for 2 hours. Thereafter, the pH was adjusted to 2 by adding nitric acid to obtain an aqueous dispersion of the resin component. In addition, colloidal silica (trade name “Snowtex O” manufactured by Nissan Chemical Industries, Ltd.) is dispersed in water at a concentration of 10% by weight, the pH is adjusted to 8 with potassium hydroxide, and the aqueous dispersion of inorganic components is dispersed. Obtained. Thereafter, 50 parts of an aqueous dispersion of an inorganic component was gradually added to and mixed with 100 parts of an aqueous dispersion of a resin component over 2 hours. Further, the mixture was stirred for 2 hours to obtain an aqueous dispersion containing preliminary particles in which silica particles adhered to PMMA particles as a resin component. Next, 2 parts of vinyltriethoxysilane was added to this aqueous dispersion, and after stirring for 1 hour, 1 part of TEOS was added and the temperature was raised to 60 ° C. Thereafter, stirring was continued for 3 hours, and the mixture was cooled to obtain a stock solution of composite particles containing the composite particles at a concentration of 10 wt%.
[0087]
By combining the stock solution of composite particles thus obtained with the stock solution of resin particles described above, five types (0.5, 1, 1.5, 2, and 5) of particle size ratios (composite particles d₁/ Resin particles d₂) Is obtained.
[0088]
A slurry according to the present embodiment was prepared according to the following formulation using a particle mixture of composite particles and resin particles as abrasive particles.
[0089]
First, the above-described stock solution of the resin particles and the stock solution of the composite particles were mixed and diluted with water so that the abrasive particles were contained at a concentration of 5 wt%. Further, it was prepared by mixing 5 wt% of ferric nitrate as an oxidizing agent and 90 wt% of pure water as a solvent. Since ferric nitrate is contained, the pH of the resulting slurry is in the acidic range of about 2.5. Further, a plurality of slurries were prepared by changing the mixing ratio of the two types of stock solutions to change the ratio between the resin particles and the composite particles.
[0090]
Using the various slurries thus prepared, W-CMP was performed by the following method, and the W polishing rate was examined.
[0091]
FIG. 3 is a process sectional view showing the W-CMP.
[0092]
First, as shown in FIG. 3A, a 300 nm-thick insulating film 21 was deposited on a semiconductor substrate 20 to form a hole 22 (0.1 μmφ). Further, a W film 24 of 200 nm was deposited on the entire surface via a TiN film 23 of 10 nm.
[0093]
Unnecessary portions of the TiN film 23 and the W film 24 were removed by CMP to expose the surface of the insulating film 21 as shown in FIG.
[0094]
Polishing of the W film 24 was performed as follows using the above slurry with IC1000 (manufactured by Rodale Nitta) as a polishing cloth. That is, as shown in FIG. 4, while rotating the turntable 30 to which the polishing pad 31 is attached at 100 rpm, the top ring 33 holding the semiconductor substrate 32 is moved to 300 gf / cm.²Abrasion load. The rotational speed of the top ring 33 was set to 102 rpm, and the slurry 37 was supplied onto the polishing pad 31 from the slurry supply nozzle 35 at a flow rate of 200 cc / min. FIG. 4 also shows the water supply nozzle 34 and the dresser 36.
[0095]
FIG. 5 is a graph showing the relationship between the polishing rate of the W film 24 and the ratio of the resin particles in the particle mixture in the slurry. In the graph of FIG. 5, curves a, b, c, d and e respectively represent the particle size ratio (d₁/ D₂) Shows the results for slurries of 0.5, 1, 1.5, 2, and 5.
[0096]
As shown in the graph of FIG. 5, when the composite particles or the resin particles are used alone, the W polishing rate is 10 nm / min or less. On the other hand, in the case of a slurry using a mixture of the composite type particles and the resin particles, the W polishing rate tends to increase at any particle size ratio. This is presumably because the composite particles and the resin particles form a close-packed structure on the polishing cloth, so that appropriate clogging occurs and the particles are fixed.
[0097]
In particular, as shown by the curves d and e, in the region where the particle size ratio is 2 or more and the ratio of the resin particles is 10 to 90% by weight, the W film is polished at a high polishing rate of 100 nm / min or more. Can be.
[0098]
Next, various slurries were prepared in the same manner as described above, except that the particle size ratio was set to 2, the ratio of the resin particles was fixed to 10 wt%, and the materials of the composite particles and the resin particles were changed. Using the obtained slurry, the W film was polished under the same conditions as described above, and the polishing rate of the W film was examined. The results are summarized in Table 1 below together with the viscosity of each slurry, the composition of the particle mixture, and the polarity of the zeta potential of each particle. Since the pH of the slurry is 2.5, the polarity of the zeta potential of each particle is the result of measurement under an environment of pH 2.5.
[0099]
[Table 1]

[0100]
As shown in Table 1, when the zeta potentials of the composite particles and the resin particles were both negative (Nos. 1 to 5, 10) and both were positive (No. 7), the viscosity of the slurry was high. Is 1 mPaS. Similarly, when the 樹脂 potential of the resin particles is zero (Nos. 8, 9), the slurry also has a low viscosity of 1 mPaS. When these slurries were used, the W film could be polished at a high polishing rate of 110 nm / min or more. In each case, dishing on the surface after polishing was suppressed to 10 nm or less.
[0101]
Similarly, when the type of the functional group on the surface of the resin particles was changed, and when a surfactant was added, a high polishing rate was similarly obtained. The resin component in the composite particles does not necessarily have to be the same as the material of the resin particles, and the same effect can be obtained even when different. A high polishing rate is also expected when two or more composite particles and resin particles are used in combination.
[0102]
No. The pH of the slurries 1 to 10 is about 2.5, and even when the pH is low, the slurry according to the embodiment of the present invention can ensure a sufficiently high polishing rate. Conversely, even at a high pH of 10 or more, the slurry according to the embodiment of the present invention is expected to exhibit the same effect.
[0103]
Conventional slurries containing resin particles or composite particles alone as abrasive particles could only be used in a narrow pH range of about 3 to 7. This is because a surfactant or an organic compound was added to enhance the interaction between the polishing particles and the polishing pad. In the region of strong acids and strong alkalis, no effect was obtained because these additives were deactivated.
[0104]
In the embodiment of the present invention, a sufficient interaction between the abrasive particles and the polishing pad can be obtained because the composite particles and the resin particles are mixed and used as the abrasive particles. Therefore, it has become possible to use it in a wide pH range, which was impossible in the past.
[0105]
As shown in Table 1, in the case of containing a particle mixture of composite particles having a positive ζ potential and resin particles having a negative ζ potential (No. 6), the viscosity of the slurry was as high as 12 mPaS. . As described above, it was difficult to drop the high-viscosity slurry from the slurry supply nozzle 37 onto the polishing pad 31, and the CMP could not be performed.
[0106]
(Embodiment 2)
In the Cu2nd polishing in the Cu damascene wiring formation process, in addition to the Cu film, for example, a TaN film or SiO₂A different material such as a film is polished flat. Conventionally, in such a case, non-selective polishing has been performed with a polishing rate ratio of 1. However, in the case of an organic insulating film, erosion is greatly caused by polishing under the above-described conditions due to physical effects such as hardness and hydrophobicity of the surface.
[0107]
By using the slurry according to the embodiment of the present invention, a Cu damascene wiring can be formed with low erosion even when selective polishing is performed with a polishing rate ratio of 1 or more. Moreover, scratches hardly occur on the surface of the polished organic insulating film or Cu film.
[0108]
FIG. 6 is a process sectional view showing Cu-CMP.
[0109]
First, as shown in FIG. 6A, an insulating film 41 is deposited on a semiconductor substrate 40 on which elements (not shown) are formed, and contacts 42 are formed. On the insulating film 41, LKD5109 (manufactured by JSR) as the low dielectric constant film 43 is deposited to a thickness of 200 nm, and black diamond (AMAT, hereinafter referred to as BD) as the cap film 44 is deposited to a thickness of 100 nm by a CVD method. . After grooves 45 were formed in the low dielectric constant insulating film 43 and the cap film 44 by RIE, a TaN film 46 (20 nm) and a Cu film 47 (500 nm) were deposited on the entire surface by sputtering and plating.
[0110]
Next, unnecessary portions of the Cu film 47 were removed by CMP under the following conditions to expose the TaN film 46 as shown in FIG.
[0111]
Slurry: CMS7303 / 7304 (JSR)
Flow rate: 250cc / min
Polishing cloth: IC1000 (Rodale Nitta)
Load: 300gf / cm²
The rotation speed of the carrier and the table was set to 100 rpm, and polishing was performed for 1 minute. In this step, since the polishing is stopped at the TaN film 46, the hydrophobic cap film 44 is not exposed. Therefore, polishing can be performed using a commercially available slurry.
[0112]
Thereafter, an unnecessary portion of the TaN film 46 was removed by a touch-up process as shown in FIG. In this case, the slurry according to the embodiment of the present invention is used for CMP.
[0113]
In preparing the slurry, the average particle size (d₁) Is 200 nm and the average particle diameter (d₂) Was prepared as abrasive particles with a particle mixture of 100 nm and resin particles. The particle size ratio between the composite particles and the resin particles (d₁/ D₂) Is 2. The composite particles include PMMA particles having an average particle size of 150 nm as a resin component and silica particles having an average particle size of 25 nm as an inorganic component. The resin particles are made of PMMA and have a COOH group as a functional group on the surface. The composite particles and the resin particles were prepared as stock solutions having the same concentration by the same method as described above.
[0114]
The above-described stock solution of the composite particles and the stock solution of the resin particles were mixed and diluted with pure water such that the concentration of the composite particles was 2.7 wt% and the concentration of the resin particles was 0.3 wt%. Further, 0.1 wt% of a hydrogen peroxide solution as an oxidizing agent, 0.8 wt% of a quinolinic acid as an oxidation inhibitor, an additive and the like were added, and the pH was adjusted to 10 with KOH as a pH adjusting agent.
[0115]
Also, a slurry of a comparative example was prepared according to the same formulation as described above, except that the abrasive particles were changed to two types of colloidal silica having different average particle sizes. Specifically, a mixture of 0.6 wt% of colloidal silica having an average particle diameter of 40 nm and 2.4 wt% of colloidal silica having an average particle diameter of 20 nm was used as abrasive particles.
[0116]
Each slurry was polished for 2 minutes under the same conditions as described above, and the polishing rates of the Cu film 47, the TaN film 46, and the cap film 44 were examined. The polishing time was adjusted so that the BD as the cap film 44 was polished by 50 nm. As a result, when the slurry according to the embodiment of the present invention was used, the polishing rates of the Cu film, the TaN film, and the cap film were 100 nm / min, 45 nm / min, and 20 nm / min, respectively. On the other hand, when the slurry of the comparative example was used, the polishing rate of the Cu film was 70 nm / min, and the polishing rates of the TaN film and the cap film were both 60 nm / min.
[0117]
As described above, when the slurry of the comparative example was used, erosion occurred because the polishing rate of the cap film 44 was as large as 60 nm / min, and a part of the erosion was lost. The step between the Cu film and the cap film 44 had a shape in which the Cu film protruded, and the erosion was 120 nm. Since the cap film 44 needs to protect the insulating film 43 from damage caused in the next step, it must be prevented from being broken as much as possible. On the other hand, when the slurry according to the embodiment of the present invention was used, the erosion showed a low value of 20 nm, and the cap film 44 was not broken. Since the resin particles made of an organic material are contained, the slurry according to the embodiment of the present invention can generate an appropriate interaction with an organic film.
[0118]
Further, dishing on the surface of the Cu film 47 after polishing was suppressed to 20 nm or less. Furthermore, 1 cm on the polished Cu film 47 and the cap film 44²The number of scratches was about 10,000 when the slurry of the comparative example was used, but was reduced to 100 or less when the slurry according to the embodiment of the present invention was used. By optimizing the added components, it is possible to further reduce scratches.
[0119]
(Embodiment 3)
The slurry according to the embodiment of the present invention can also be applied to formation of STI (Shallow trench isolation). FIG. 7 is a process cross-sectional view showing the process of forming the STI.
[0120]
First, as shown in FIG. 7A, a groove is formed in a semiconductor substrate 50 provided with a CMP stopper film 51, and an insulating film 52 is deposited thereon. Here, SiN is used as the CMP stopper film 51, and a coating type insulating film such as organic SOG can be used as the insulating film 52, for example.
[0121]
Next, unnecessary portions of the insulating film 52 were removed by CMP using the slurry according to the embodiment of the present invention, and the surface of the CMP stopper film 51 was exposed as shown in FIG. The slurry has an average particle size (d₁) Is 200 nm and the average particle diameter (d₂) Was prepared using a particle mixture of 100 nm and resin particles as abrasive particles. The particle size ratio between the composite particles and the resin particles (d₁/ D₂) Is 2. The composite particles include PST particles having an average particle size of 200 nm as a resin component and silica particles having an average particle size of 40 nm as an inorganic component. In synthesizing such composite particles, first, 92 parts of styrene, 4 parts of methacrylic acid, 4 parts of hydroxyethyl acrylate, 0.1 part of ammonium lauryl sulfate, 0.5 part of ammonium persulfate, and 400 parts of ion-exchanged water were added in a capacity of 2 parts. Housed in liter flask. The mixture was heated to 70 ° C. while stirring under a nitrogen gas atmosphere, and polymerized for 6 hours. Thus, a stock solution of resin particles containing PST particles having a carboxyl group at a concentration of 20 wt% was obtained. In synthesizing the PST particles, 1 part of divinylbenzene (purity: 55%) was added as a crosslinking agent. When forming a functional group other than COOH, a pyridine ring compound (amino group), a sulfonate (sulfone group), or the like can be used.
[0122]
At the time of compounding, first, 100 parts of an aqueous dispersion containing 10% by weight of PST particles was placed in a flask having a capacity of 2 liters, and 1 part of methyltrimethoxysilane was added. The mixture was stirred at 40 ° C. for 2 hours. Thereafter, the pH was adjusted to 2 by adding nitric acid to obtain an aqueous dispersion of the resin component. In addition, colloidal silica (trade name “Snowtex O” manufactured by Nissan Chemical Industries, Ltd.) is dispersed in water at a concentration of 10% by weight, the pH is adjusted to 8 with potassium hydroxide, and the aqueous dispersion of inorganic components is dispersed. Obtained. Thereafter, 50 parts of an aqueous dispersion of an inorganic component was gradually added to and mixed with 100 parts of an aqueous dispersion of a resin component over 2 hours. Further, stirring was performed for 2 hours to obtain an aqueous dispersion containing preliminary particles in which silica particles were attached to polymer particles. Next, 2 parts of vinyltriethoxysilane was added to this aqueous dispersion, and after stirring for 1 hour, 1 part of TEOS was added and the temperature was raised to 60 ° C. Thereafter, stirring was continued for 3 hours, and the mixture was cooled to prepare a stock solution of composite particles containing the composite particles at a concentration of 10 wt%.
[0123]
The above-mentioned concentrated solution of the stock solution of the composite particles and the stock solution of the resin particles were mixed and diluted with pure water so that the concentration of the composite particles became 18 wt% and the concentration of the resin particles became 2 wt%. Here, the supernatant liquid of the stock solution of the composite particles was removed by a particle sedimentation method to reduce the concentration of the composite particles to 20 wt%, and the above-mentioned resin containing the cross-linked PST particles at a concentration of 20 wt%. A stock solution of particles was used. Further, the pH was adjusted to 11 with KOH as a pH adjuster.
[0124]
The insulating film 52 was polished using the obtained slurry under the following conditions.
[0125]
Slurry flow rate: 300cc / min
Polishing cloth: IC1000 (Rodel Nitta)
Polishing load: 300gf / cm²
Polishing was performed for 3 minutes with the rotation speed of both the top ring and the table set to 100 rpm.
[0126]
C and SiN used as the material of the CMP stopper film 51 have hydrophobicity in many cases, and the ζ potential is the isoelectric point. For this reason, it is in an environment where scratches easily occur.
[0127]
By using the slurry according to the present embodiment, the number of scratches on the polished wafer surface was limited to two, and the erosion was suppressed to 30 nm or less. In this manner, the effect was confirmed even when the insulating film on the CMP stopper film, which easily causes scratches, was subjected to CMP.
[0128]
【The invention's effect】
As described above, according to the aspect of the present invention, a slurry capable of reducing dishing and erosion and polishing a surface to be polished at a practical polishing rate is provided. According to another aspect of the present invention, there is provided a method of polishing a surface to be polished at a practical polishing rate while reducing dishing and erosion. According to another aspect of the present invention, a method for manufacturing a semiconductor device having high reliability is provided.
[0129]
According to the present invention, for example, it is possible to manufacture a high-performance and high-speed semiconductor device having wiring of a design rule of 0.1 μm or less required in the next generation, and its industrial value is enormous.
[Brief description of the drawings]
FIG. 1 is a schematic diagram schematically showing a state of a cross section of a composite particle and a resin particle.
FIG. 2 is a sectional view of a top ring.
FIG. 3 is a process sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the present invention.
FIG. 4 is a schematic diagram showing a state of CMP.
FIG. 5 is a diagram showing the relationship between the polishing rate of a W film and the content of resin particles in a slurry.
FIG. 6 is a process sectional view illustrating a method for manufacturing a semiconductor device according to another embodiment of the present invention.
FIG. 7 is a process sectional view illustrating the method of manufacturing the semiconductor device according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Composite particle, 11 ... Resin component, 12 ... Inorganic component, 13 ... Resin particles, 20 ... Semiconductor substrate, 21 ... Insulating film, 22 ... Hole, 23 ... TiN film, 24 ... W film, 30 ... Turntable, 31 polishing pad, 32 semiconductor substrate, 33 top ring, 34 water supply nozzle, 35 slurry supply nozzle, 36 dresser, 37 slurry, 40 semiconductor substrate, 41 insulating film, 42 contact, 43 .. Low dielectric constant film, 44 cap film, 45 groove, 46 TaN film, 47 Cu film, 50 semiconductor substrate, 51 CMP stopper film, 52 insulating film, 60 semiconductor substrate, 61 retaining ring , 62 ... polishing cloth, 63 ... housing, 64 ... air supply pipe, 65 ... chucking plate, 66 ... air bag, 67 ... top ring, 68 ... top ring, 69 ... backing Lum.

Claims (7)

A slurry for CMP, comprising composite particles containing a resin component and an inorganic component, and resin particles, having a viscosity of less than 10 mPaS. The slurry according to claim 1, wherein the composite particles and the resin particles have the same polarity. The slurry for CMP according to claim 1, wherein one of the composite particles and the resin particles has an isoelectric point. The particle diameter ratio (d ₁ / d ₂ ) of the average particle diameter d ₁ of the composite particles and the average particle diameter d ₂ of the resin particles is 2 or more. The slurry for CMP according to claim 1 or 2. The slurry for CMP according to any one of claims 1 to 4, wherein the content of the resin particles is 10 wt% or more and 90 wt% or less of the total amount of the composite particles and the resin particles. The slurry for CMP according to any one of claims 1 to 5, wherein a semiconductor substrate having a surface to be polished is brought into contact with the polishing cloth adhered on the turntable while rotating, and the polishing cloth is coated on the polishing cloth. And polishing the surface to be polished by dropping. Forming an insulating film on the semiconductor substrate;
Forming a recess in the insulating film;
Depositing a conductive material inside the recess and on the insulating film to form a layer having conductivity;
Removing the conductive material deposited on the insulating film to expose the surface of the insulating film, thereby leaving the conductive material inside the concave portion,
6. A method of manufacturing a semiconductor device according to claim 1, wherein the removal of the conductive material deposited on the insulating film is performed by CMP using a slurry according to claim 1.

Images