JP3668046B2 - Polishing cloth and method for manufacturing semiconductor device using the polishing cloth - Google Patents

Description

【００５１】
従来の研磨布ＩＣ−１０００の場合、コンディショニング処理を行わないと、研磨速度が６０ｎｍ／ｍｉｎであり、コンディショニング処理を行った場合の研磨速度２１０ｎｍ／ｍｉｎに比べて極端に遅くなっている。
【００５２】
コンディショニング処理を行わない研磨速度が遅いのは、研磨布の表面層でスラリーの保持が行われていないためだと考えられる。
【００５３】
それに対し、本実施形態の研磨布は、コンディショニング処理を行わなくても２０５ｎｍ／ｍｉｎと大きな研磨速度が得られた。これは、研磨布表面に露出した水溶性フィラーが水（スラリー）に溶け、水溶性フィラーの存在していた領域が凹部となって表面積が大きくなるため、スラリーの保持性が良くなるためである。
【００５４】
コンディショニング処理を行わない研磨速度が遅いのは、表面層でスラリーの保持が行われていないためだと考えられる。
【００５５】
それに対し、本実施形態の研磨布は、コンディショニング処理を行わなくても２０５ｎｍ／ｍｉｎと大きな研磨速度が得られた。これは、研磨布表面に露出した水溶性フィラーが水（スラリー）に溶け、水溶性フィラーの存在していた領域が凹部となって表面積が大きくなるため、スラリーの保持性が良くなるためである。
【００５６】
コンディショニング処理を行わない研磨速度が遅いのは、表面層でスラリーの保持が行われていないためだと考えられる。
【００５７】
それに対し、本実施形態の研磨布は、コンディショニング処理を行わなくても２０５ｎｍ／ｍｉｎと大きな研磨速度が得られた。これは、研磨布表面に露出した水溶性フィラーが水（スラリー）に溶け、水溶性フィラーの存在していた領域が凹部となって表面積が大きくなるため、スラリーの保持性が良くなるためである。
【００５８】
コンディショニング処理を行わない研磨速度が遅いのは、研磨布の表面層でスラリーの保持が行われていないためだと考えられる。
【００５９】
それに対し、本実施形態の研磨布は、コンディショニング処理を行わなくても２０５ｎｍ／ｍｉｎと大きな研磨速度が得られた。これは、研磨布表面に露出した水溶性フィラーが水（スラリー）に溶け、水溶性フィラーの存在していた領域が凹部となって表面積が大きくなるため、スラリーの保持性が良くなるためである。
【００６０】
また、本実施形態の研磨布は、研磨速度が安定して得られていた。これは、研磨中に母材１１の表面層が少しずつすり減ってゆきながら、水溶性フィラー１２が露出し、スラリーによって水溶性フィラー１２が溶けてしまい、新たな凹部が形成されるためである。
【００６１】
また、研磨布１０のコンディショニングを行いながら使用した場合、コンディショニングを行わないものや、ポリテックスや従来の研磨布ＩＣ−１０００に比べて非常に大きな、３１０ｎｍ／ｍｉｎの研磨速度が得られた。
【００６２】
また、被研磨材としての図３に示す試料を用いて、ディッシング量の評価を行った。前記試料は、Ｓｉ基板２１上に凹凸を有するシリコン酸化膜２２が形成され、このシリコン酸化膜２２の全面にＡｌ膜２３が堆積されている。
【００６３】
なお、Ａｌ膜２３の膜厚は８００ｎｍ、シリコン酸化膜２２の膜厚は、７００ｎｍ、シリコン酸化膜２２に形成された凹部の高さは４００ｎｍである。また、凹部の幅Ａと、凹部の配置間隔Ｂの関係が、Ａ／（Ａ＋Ｂ）が０．７になるようにしつつ、凹部の幅Ａを１０μｍと１００μｍの場合で評価を行った。
【００６４】
なお、Ａｌ膜２３が研磨され、表面が２３ｂまで研磨された際のディッシング量で評価を行った。
【００６５】
ディッシング量の評価結果を表２に示す。
【００６６】
【表２】

【００６７】
非常に軟らかい研磨布であるポリテックスを用いて研磨を行った場合のディッシング量は、１０ｎｍの配線間隔でも１６０ｎｍあり、１００ｎｍの配線間隔Ａでは３５０ｎｍ以上もあった。
【００６８】
また、コンディショニングが行われた従来の研磨布ＩＣ−１０００を用いて研磨を行った場合のディッシング量は、８０ｎｍ（Ａ＝１０μｍ），２１０ｎｍ（Ａ＝１００μｍ）であり、ポリテックスを用いた場合よりは改善されているが、やはり非常に大きい値である。
【００６９】
コンディショニングによりＩＣ−１０００の表面層には軟らかい層が形成されて研磨の際に被研磨材の表面層における平坦化性に悪影響を及ぼすため、コンディショニングを行わないで研磨を行ったほうが、ディッシング量が小さくなると考えられる。
【００７０】
ところが、結果は逆で、コンディショニングを行わずに研磨を行った場合のディッシング量は、２００ｎｍ（Ａ＝１０μｍ），２５０ｎｍ（Ａ＝１００μｍ）であり、コンディショニングを行った場合よりも悪くなっている。
【００７１】
これは、コンディショニングを行わないと、Ａｌの表面に深い傷（＞２００ｎｍ）がつき、傷が拡大する形でＡｌの浸食が進むためである。
【００７２】
これらの結果に対し、コンディショニングが行われていない本発明の上記実施形態の研磨布１０を用いて研磨を行った場合のディッシング量は、間隔Ａが１０μｍのもので８ｎｍ、間隔Ａが１００μｍのもので４０ｎｍであり、ディッシングが著しく改善されている。
【００７３】
母材自体の圧縮弾性率が１０ＧＰａと非常に硬いこと、また表面層の軟らかい層が、被研磨材表面にスクラッチを生じさせず、且つ母材表面がスラリーを十分に保持し、この表面層の軟らかい層の厚さが、非常に薄くなるよう制御されていることのためディッシングの改善がなされた。
【００７４】
また、コンディショニング処理が行われた研磨布１０を用いて研磨した場合のディッシング量は、２０ｎｍ（Ａ＝１０μｍ），８０ｎｍ（Ａ＝１００μｍ）であった。
【００７５】
ディッシング量が悪化したのは、コンディショニングにより、研磨布の表面の軟らかい層がより軟らかくなった為か、軟らかい層が厚くなった為、若しくはその両方のためである。
【００７６】
次に、水溶性フィラー１２の粒径を変えてＡｌ膜に対する研磨速度の評価を行った。なお、全ての粒径で水溶性フィラーの濃度を２５ｗｔ％に固定して研磨布を製造した。その結果を表３に示す。
【００７７】
【表３】

【００７８】
表３から、水溶性フィラー１２の粒径に応じて研磨速度が変化していることが確認された。粒径が１μｍの場合、被研磨材であるＡｌ膜の表面に多数のスクラッチが発生していた。
【００７９】
これは、研磨布の粒径が小さすぎるため、研磨布の表面に形成される凹凸が微細すぎて、表面に軟らかな層が形成されなかったのと同時に、スラリーの保持が困難であったためである。
【００８０】
一方、粒径が５０μｍ及び１００μｍの場合、研磨速度が遅くなっている。これは、凹凸が大きすぎたためと考えられる。以上の結果から、水溶性フィラーの粒径は、５乃至３０μｍ程度が好ましいと言える。
【００８１】
以上説明したように、本実施形態の研磨布は、凹凸が形成され軟らかい表面層と、母材及び固体の水溶性フィラーからなる硬い内部層とから構成されているので、理想的な研磨布にほぼ等しくなる。
【００８２】
従って、研磨布の凹凸のある軟らかい表面層によって、研磨速度の向上及び被研磨材の表面層に生ずるスクラッチの形成が抑制されると共に、研磨布の内部の硬い層によって平坦化の向上を図ることができる。
【００８３】
また、本発明の研磨布は、母材の表面層が削れても新しい、水溶性フィラーが露出して水又はスラリーに溶け出すので、常に表面層に軟らかい層が存在するので、安定した研磨速度を得ることができる。
【００８４】
また、軟らかい表面層が自動的に形成されるので、コンディショニング処理をほとんど必要としないので、研磨布の寿命が長くなる。
【００８５】
（第２実施形態）
図４は、本発明の第２実施形態に係わる研磨布の構成を示す断面図である。
【００８６】
なお、図４において、図２と同一なものには同一符号を付し、その詳細な説明を省略する。
【００８７】
本実施形態の特徴は、水溶性フィラー１２の表面が、水（スラリー）に対して不溶性の材料からなるコーティング層３１でコーティングされていることである。
【００８８】
水溶性フィラーを多量に母材中に混入させた場合、水溶性フィラー同士が接触する確率が高くなる。複数の水溶性フィラー同士が接触した状態で、水につけると、図５に示すように、深い凹部４１が形成されてしまう。
【００８９】
しかし、本実施形態のように、コーティング層でコーティングすることで、接触している水溶性フィラー１２が、全て溶けることがない。従って、母材内の奥深くまで凹部が形成されることによる、弾性率の低下を防ぐことができる。
【００９０】
なお、本発明は、上記実施形態に限定されるものではない。例えば、上記実施形態では、母材としてポリスチレンを、また水溶性フィラーとしてセルロースを例として挙げたが、他の材料を用いることができる。
【００９１】
また、固体の水溶性フィラーの代わりに、液体を母材中に分散混入させても良い。液体は、固体に比べて軟らかいが、気体に比べれば十分硬いので、水溶性フィラーの替わりに用いることができる。もちろん、表面に露出した液体は流れ出るので、液体が存在していた領域に凹部が形成され、固体の水溶性フィラーと同様の効果を持つ。
【００９２】
また、母材中に混入される微粒子としては、水溶性だけでなく、他の溶媒に対して溶けるようなもので有ればよい。研磨処理を行う前に、研磨布の表面に微粒子を溶かし得る溶媒を浴びせることによって微粒子を溶かし凹部を形成すればよい。
【００９３】
次に、上記研磨布を用いて、配線溝を有するダマシン配線構造の半導体装置を製造する方法の実施態様について説明する。
【００９４】
図６は、ＳｉＯ_２基板１に設けられた配線溝２中にＡｌ配線３を埋め込むダマシン配線構造の部分的な断面図を示している。
【００９５】
配線溝２の深さは、４，０００Å（オングストローム）、幅は、１００μm、及び研磨前におけるＡｌ配線３のＡｌ層の厚さを８，０００Å（オングストローム）とする。
【００９６】
このような構造で、配線溝２にＡｌ配線３を埋め込み、上方からＡｌ配線３の表面を研磨布で研磨したとき、ＳｉＯ_２基板１の表面以下の溝内にまでオーバーポリシング（Over Polishing）してしまい、いわゆるデッシング（Dishing）又は シニング（Thinning）が生じてしまう。
【００９７】
この実施態様において、荷重３００g/ｃｍ² 、テーブル及びキャリアの回転数５０rpmで平坦性の評価を行った。その結果、配線溝２に埋め込まれたＡｌ配線３上のスクラッチは、ＫＬＡで評価を行ったところ、従来の研磨布ＩＣ−１０００では、４２，３２８個／Wafer、観察された。
【００９８】
これに対し、本発明の研磨布は、３２０個の／Waferのスクラッチが観察されたに過ぎなかった。
本発明の研磨布において、デッシング（Dishing）の発生が従来の研磨布と比較して格段に改善されたことを図７に示す。
【００９９】
従来の研磨布ＩＣ−１０００を用いてＡｌ配線３を研磨したときに発生するデッシング（Dishing）の数は、点線で示すようにオーバーポリシング（Over Polishing）が溝の深さの６０％に至ると３５００Dishing（Å）を越えてしまう。
【０１００】
これに対して本発明の内部に分散された微粒子を含む研磨布は、Ａｌ_２Ｏ_３を３ｗｔ％、（ＮＨ_４）_２Ｓ_２Ｏ_８を１ｗｔ％、及びベンズトリアゾールを０．０２％としたスラリーを表面に保持させたものを採用して、Ａｌ配線３の表面を研磨したとき、発生するデッシング（Dishing) の数は、実線で示すようにオーバポリシングス（Over Polishing）が溝の深さの６０％に達したときであっても、殆ど増加しない。
【０１０１】
このことは、Ａｌ配線３の品質、特性が向上したことを意味し配線形成が良好に行われたと言える。
【０１０２】
図８は、ＳｉＯ_２基板１に設けられた配線溝２中にＣｕ配線4を埋め込むダマシン配線構造の部分的な断面図を示している。
【０１０３】
配線溝２の深さは、４，０００Å（オングストローム）、幅は、１００μm、及び研磨前におけるＣｕ配線４のＣｕ層の厚さを８，０００Å（オングストローム）とする。
【０１０４】
本発明の研磨布において、デッシング（Dishing)の発生が従来の研磨布と比較して格段に改善されたことを図９に示す。
【０１０５】
従来の研磨布ＩＣ−１０００を用いてＣｕ配線4を研磨したときに発生するデッシング（Dishing)の数は、点線で示すようにオーバポリシング（Over Polishing）が溝の深さの６０％に至ると３５００Dishing （Å）の近傍に達する。
【０１０６】
これに対して、本発明の実施態様の、内部に分散された微粒子を含む研磨布は、Ａｌ_２Ｏ_３を１ｗｔ％、（ＮＨ_４）_２Ｓ_２Ｏ_８を１ｗｔ％ 及びベンズトリアゾールを０．０５％としたスラリーを表面に保持させたものを採用して、Ｃｕ配線4の表面を研磨したとき、発生するデッシング（Dishing) の数は、実線で示すようにオーバポリシング（Over Polishing）が溝の深さの６０％に達したときであっても、僅かしか増加しない。
【０１０７】
図１０は、ＳｉＯ_２基板１に設けられた配線溝２中にＷ配線層５を埋め込むダマシン配線構造の部分的な断面図を示している。
【０１０８】
配線溝２の深さは、４，０００Å（オングストローム）、幅は、１００μm、及び研磨前におけるＷ配線層５のＷ層の厚さを８，０００Å（オングストローム）とする。
【０１０９】
本発明の研磨布において、デッシング（Dishing)の発生が従来の研磨布と比較して格段に改善されたことを図１１に示す。
【０１１０】
従来の研磨布ＩＣ−１０００を用いてＷ配線５を研磨したときに発生する
デッシング（Dishing)の数は、点線で示すようにオーバポリシング（Over Polishing）が溝の深さの６０％に至ると３５００Dishing ／Åを越える。
【０１１１】
これに対して本発明の内部に分散された微粒子を含む研磨布は、Ａｌ_２Ｏ_３を３ｗｔ％、Ｆｅ（ＮＯ_３）_３を５ｗｔ％ としたスラリーを表面に保持させたものを採用して、Ｗ配線５の表面を研磨したとき、発生するデッシング（Dishing)の数は、実線で示すようにオーバポリシング（Over Polishing）が溝の深さの６０％に達したときであっても、僅かしか増加しない。
【０１１２】
次に、本発明の他の実施態様として、図１２に示すように、Ｓｉ基板１上の厚さ１４，０００Å（オングストローム）の酸化膜６を、深さ７，０００Å（オングストローム）、幅が、１００μmの配線溝２内に埋設し、本発明の研磨布で酸化膜６を上面から研磨する。このときのスラリーは、Cabot社製ＳＣ−１を純水で３倍希釈したものを用いる。
【０１１３】
その結果、図１３に示すように、従来の研磨布ＩＣ−１０００と本発明の研磨布とを比較したとき、同一のオキサイド・リムーバル（Oxide Removal）量Å（オングストローム）を得るのに、リメイニング・ステップ（Remaining Step）量Å（オングストローム）は、本発明の研磨布の方がより理想的曲線に近付いていることが分かる。
【０１１４】
それによって、本発明の研磨布を用いて酸化膜の表面を研磨することによって、ばらつきのない平坦化が実現できる。
【０１１５】
その他、本発明は、その要旨を逸脱しない範囲で、種々変形して実施することが可能である。
【０１１６】
【発明の効果】
以上説明したように本発明の研磨布によれば、被研磨材の表面を機械的に研磨するための母材中に、溶媒に対して可溶である微粒子を分散混入することによって、特に、研磨中に前記微粒子が前記溶媒に溶けて、研磨布の表面に凹部を形成するので、被研磨材の表面層上において、高い平坦化性能，安定した研磨速度が得られ、被研磨材の表面でのスクラッチの発生を抑制できる。
【０１１７】
又、基板上に配線溝を設け、この配線溝中に金属配線を埋め込み、前記金属配線の不要部分を、母材中に溶媒に対して可溶である微粒子を分散混入して構成した研磨布で研磨し除去することにより、前記金属配線（特にダマシン配線）のクオリティを高めることができる。
【０１１８】
更に、この発明の研磨布を用いた半導体の製造方法は、配線溝中に金属配線に替え酸化膜を埋設した場合でも、本発明の研磨布で研磨することにより、前記酸化膜の表面を良好に平坦化できる。
【図面の簡単な説明】
【図１】理想的な研磨布の構成を示す模式図。
【図２】本発明の第１実施形態に係わる研磨布の構成を示す部分的断面図。
【図３】研磨布の評価に用いた被研磨体の構成を部分的に示す断面図。
【図４】本発明の第２の実施形態に係わる研磨布の構成を示す部分的断面図。
【図５】研磨布の微粒子同士が接触することによって生ずる問題点を説明するための研磨布の断面図。
【図６】本発明の研磨布を用いて研磨される埋め込み配線（ダマシン配線）構造の金属配線がAl である場合の半導体装置の形成過程を示す要部断面図。
【図７】本発明の研磨布を用いて図５に示す金属配線Alを研磨したときのデッシング（Dishing)の発生を従来例と比較したときの図。
【図８】本発明の研磨布を用いて研磨される埋め込み配線（ダマシン配線）構造の金属配線がCu である場合の半導体装置の形成過程を示す要部断面図。
【図９】本発明の研磨布を用いて図７に示す金属配線Cuを研磨したときのデッシング（Dishing)の発生を従来例と比較したときの図。
【図１０】本発明の研磨布を用いて研磨される埋め込み配線（ダマシン配線）構造の金属配線がW である場合の半導体装置の形成過程を示す要部断面図。
【図１１】本発明の研磨布を用いて図９に示す金属配線Wを研磨したときのデッシング（Dishing)の発生を従来例と比較したときの図。
【図１２】本発明の半導体装置の製造方法に係る応用例を示し、基板に設けられた溝中に埋め込まれた酸化膜を本発明の研磨布を用いて研磨する半導体装置の形成過程を示す要部断面図。
【図１３】本発明の研磨布を用いて図１０に示す酸化膜を研磨したときの同一リメイニングステップ（Remaining step）/Åにおいてオキサイド・リムーバル（Oxide Removal）の値が従来例と比較して改善されたことを示す図。
【符号の説明】
１０…研磨布
１１…母材
１２…水溶性フィラー（微粒子）
３１…コーティング層
１…ＳｉＯ_２ 基板
２…配線溝
３…金属配線Ａｌ
４…金属配線Ｃｕ
５…金属配線Ｗ
６…酸化膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing cloth used for chemical mechanical polishing (CMP) and a method for manufacturing a semiconductor device using the polishing cloth.
[0002]
[Prior art]
At present, a chemical mechanical polishing (CMP) method in which an insulating material or a wiring material is polished and its surface is flattened is attracting attention.
There are roughly two types of polishing cloths used for polishing. One is represented by Politex (Rodel) and does not require pad conditioning (dressing).
[0003]
Since Polytex has a cross-sectional structure in which takotsubo are arranged, it has excellent retention of slurry (water, SiO2, Al203, chemicals (oxidant), etc.) used during polishing. Further, the surface is very flexible and does not cause a sharp scratch on the surface of the material to be polished after polishing.
[0004]
However, the compression elastic modulus of this polishing cloth is very soft because it is less than 10 MPa. Therefore, when politex is used in the planarization process of the material to be polished, there is a problem that the polishing rate is very slow and the planarization property is inferior.
[0005]
The other is a cloth represented by IC-1000 (Rodel). Bubbles are formed inside IC-1000, and the compression elastic modulus is about 200 MPa, which is considerably harder than that of Polytex.
[0006]
Normally, the polishing cloth of IC-1000 uses a diamond conditioning plate, and in the case of a semiconductor device, the wafer as the polishing agent is polished one by one for the pad conditioning process, and the surface layer of the polishing cloth of IC-1000 is formed. Scratch to form a soft layer.
[0007]
This is to prevent the polishing rate from being extremely slow because the surface layer is hard and the ratio of the slurry held is reduced unless the conditioning treatment is performed.
[0008]
On the other hand, the life of the polishing cloth of IC-1000 is determined by the number of conditioning processes. This is because the surface layer is scratched by the conditioning treatment.
[0009]
Incidentally, after the conditioning treatment of 1000 wafers as the material to be polished, the surface layer of the polishing cloth is lost by about 850 μm compared to the state before the processing. In order to prolong the service life, when the conditioning conditions are eased so as to reduce the amount of scratching of the surface layer of the polishing cloth, the polishing rate becomes slow or unstable.
[0010]
Further, a soft layer (compression elastic modulus of 10 MPa or less) having a thickness of about several tens of μm is formed on the surface of the polishing pad immediately after conditioning, and this soft layer inhibits flatness.
[0011]
Furthermore, this soft layer is compressed and hardened with the progress of polishing. Therefore, the surface layer of the material to be polished has little scratch immediately after the start of polishing, but the scratch generated on the surface layer of the material to be polished increases when the polishing cloth is compressed and hardened for a long time after polishing. .
[0012]
As described above, the polishing cloth represented by POLITEX has a soft layer, which is the surface layer, and therefore there is a problem that the polishing rate and flatness are inferior although there are few scratches generated on the surface layer of the material to be polished. there were.
[0013]
Further, the polishing cloth represented by IC-1000 has a problem that many scratches are generated on the surface layer of the material to be polished as the polishing time becomes long unless conditioning treatment is performed.
[0014]
On the other hand, when conditioning is performed, the surface of the polishing cloth is scratched and thins, resulting in a short life.
[0015]
Further, when the semiconductor device is polished for forming a buried wiring (damascene wiring), for example, using the above-described conventional polishing cloth, dishing or thinning occurs due to over polishing. .
[0016]
This brings about drawbacks such as short-circuiting the wiring formed in the upper layer in the lithography process, and increasing the resistance due to the length of the wiring becoming wavy.
[0017]
[Problems to be solved by the invention]
The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional polishing cloth, to have a high leveling performance on the material to be polished, to obtain a stable polishing speed, and to suppress the generation of scratches on the surface of the material to be polished. And a method of manufacturing a semiconductor device using the polishing cloth.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0019]
The polishing cloth of the present invention (Claim 1) is dispersed in the base material that holds the slurry on the surface and mechanically polishes the surface of the substrate to be processed. water Soluble on the surface and the surface water And fine particles on which a coating layer that is insoluble is formed.
[0020]
At this time, when the surface of the substrate to be processed is mechanically polished on the surface of the base material (Claim 2), the fine particles present on the surface are water A concave portion corresponding to the fine particles is formed by being dissolved in the material.
[0021]
The fine particles (Claim 1) are formed on the surface of the fine particles. water Since the coating layer is insoluble to the inside of the base material, a plurality of fine particles come into contact with each other inside the base material, and all the fine particles in contact with the base material melt, forming a large recess from the surface to the inside, and softening the inside Can be prevented.
[0022]
At this time, the base material (Claim 4) has no voids inside. This is for maintaining the hardness for ensuring flatness when the surface of the material to be polished is polished.
[0024]
The fine particles ( Claim 5 ) Preferably has a particle size of 5 to 30 μm in order to increase the polishing rate.
[0025]
The polishing cloth of the present invention (Claim 3) water Soluble on the surface water When the fine particles formed by forming a coating layer insoluble in the dispersion are dispersed and the surface of the material to be polished is mechanically polished, the slurry is held on the surface, and the fine particles are water And a base material in which concave portions corresponding to the fine particles are formed on the surface. In this case, the fine particles are exposed while the surface layer of the base material gradually decreases during polishing, water As a result, the fine particles are melted and a new recess is formed in the surface layer.
[0026]
At this time, the fine particles (Claim 3) water Since a coating layer that is insoluble in the base material is formed, a plurality of fine particles come into contact with each other inside the base material, and all the fine particles that come into contact melt, forming a large recess from the surface to the inside, and softening the inside. To prevent it.
[0027]
At this time, the base material ( Claim 4 ) Has no voids inside. This is for maintaining the hardness for ensuring flatness when the surface of the material to be polished is polished.
[0029]
The fine particles ( Claim 5 ) Preferably has a particle size of 5 to 30 μm in order to increase the polishing rate.
[0030]
Also, a method of manufacturing a semiconductor device using the polishing cloth of the present invention ( Claim 6 ) Forming an insulating film on the substrate and then providing a wiring groove on the substrate through the insulating film; providing a metal wiring layer on the substrate and the wiring groove; and the metal wiring in the wiring groove A base material that holds the slurry on the surface and mechanically polishes the surface of the material to be polished, and is dispersed in the base material, is soluble in a solvent, and is on the surface. A step of polishing and removing unnecessary portions of the metal wiring embedded in the wiring groove with a polishing cloth comprising fine particles forming a coating layer insoluble in a solvent, and flattening the surface of the metal wiring And including.
[0031]
At this time, the metal wiring is mainly composed of Al ( Claim 7 ) And the main component is Cu ( Claim 8 ) Or the main component is W ( Claim 9 ).
[0032]
Furthermore, a method for manufacturing a semiconductor device using the polishing cloth of the present invention ( Claim 10 ) Providing a groove in the substrate; providing an oxide film on the substrate; embedding the oxide film in the groove; and holding the slurry on the surface and mechanically polishing the surface of the material to be polished. A polishing cloth comprising a base material to be polished and fine particles that are dispersed in the base material and have a coating layer that is soluble in a solvent and insoluble in the solvent on the surface thereof. Polishing and removing unnecessary portions of the oxide film buried in the substrate, and planarizing the surface of the oxide film.
[0033]
At this time, the oxide film ( Claim 11 ) Is preferably SiO ₂ It is.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Before describing the embodiment of the present invention, the configuration of an ideal polishing cloth in terms of performance will be described with reference to FIG.
[0035]
A polishing cloth as shown in FIG. 13 is conceivable in order to satisfy the conditions of stable polishing speed, high planarization performance of the surface of the material to be polished, suppression of generation of scratches and long life.
[0036]
The inner layer 51 is preferably hard in order to ensure flatness. The surface layer 52 is preferably soft in order to reduce the occurrence of scratches. However, it is preferable that the soft surface layer 52 be extremely thin in order to prevent deterioration in flatness. Further, the surface layer 52 should have an appropriate surface area in order to hold the slurry.
[0037]
The polishing cloth of the present invention has all the above conditions. The inside of the polishing cloth has a hard structure because fine particles are dispersed in the base material. Further, unlike the conventional polishing cloth IC-1000, since there is no hole, it is hard.
[0038]
Further, the surface layer of the polishing cloth has water-soluble fine particles exposed on the surface dissolved in a solvent to form a concave portion. Therefore, the surface layer is widened by forming irregularities on the surface, and the slurry retainability is good.
[0039]
Further, when the surface is uneven, the surface becomes softer than the inside, so that the generation of scratches is suppressed.
[0040]
In another embodiment of the present invention, when the surface of the fine particles is coated, even if a plurality of fine particles are in contact with each other, all of the fine particles in contact are not melted.
[0041]
When all the fine particles that come in contact melt, a large recess is formed and the inner layer becomes soft, but by coating the surface, only the fine particles exposed on the surface are soluble in the solvent, Since the fine particles are not melted, a large concave portion is not formed.
[0042]
When the solvent is water or slurry, even if the surface is scraped during the polishing step, the newly exposed fine particles are dissolved into the water or slurry, so that there is little deterioration in performance during polishing.
[0043]
Further, when the particle size of the fine particles is 5 to 30 μm, the polishing rate is fast.
[0044]
More specifically, an embodiment of the present invention will be described with reference to FIG.
[0045]
[First Embodiment]
FIG. 2 is a cross-sectional view showing the structure of the CMP polishing cloth according to the first embodiment of the present invention. In this polishing cloth 10, for example, a water-soluble filler 12 made of cellulose, for example, is dispersed and mixed in a base material 11 made of polystyrene, for example, at about 25 wt%.
[0046]
Since the base material 11 is hard and the water-soluble filler 12 is solid, it is difficult to be compressed. Therefore, the compressive elastic modulus of the polishing pad 10 is 10 GPa or more.
[0047]
When the water-soluble filler 12 is exposed on the surface of the polishing pad 10, the water-soluble filler 12 is dissolved in water, so that a recess is formed and the surface area is increased. When the surface area is increased, the surface becomes soft, so that scratches are not formed on the surface of the material to be polished during polishing, and the retention of the slurry is improved.
[0048]
In addition, since the soft surface layer changes the density and thickness of the concave portions formed on the surface by controlling the particle size and mixing ratio of the water-soluble filler, the thickness can be easily controlled. Is possible. Therefore, it is possible to easily control the softness and thickness of the surface layer by controlling the particle size and mixing rate of the water-soluble filler.
[0049]
Table 1 shows the polishing rate and the occurrence of scratches when polishing an Al material containing 0.5% Cu using the polishing cloth 10 and the conventional representative polishing cloth, Polytex and IC-1000. It is shown in 1.
[0050]
[Table 1]

[0051]
In the case of the conventional polishing cloth IC-1000, if the conditioning process is not performed, the polishing rate is 60 nm / min, which is extremely slow compared to the polishing rate 210 nm / min when the conditioning process is performed.
[0052]
The reason why the polishing rate without the conditioning treatment is low is considered to be because the slurry is not retained on the surface layer of the polishing pad.
[0053]
On the other hand, the polishing cloth of this embodiment has a large polishing rate of 205 nm / min even without conditioning treatment. This is because the water-soluble filler exposed on the surface of the polishing cloth is dissolved in water (slurry), and the area where the water-soluble filler was present becomes a concave portion and the surface area is increased, so that the retention of the slurry is improved. .
[0054]
The reason why the polishing rate without the conditioning treatment is low is considered to be because the slurry is not retained in the surface layer.
[0055]
On the other hand, the polishing cloth of this embodiment has a large polishing rate of 205 nm / min even without conditioning treatment. This is because the water-soluble filler exposed on the surface of the polishing cloth is dissolved in water (slurry), and the area where the water-soluble filler was present becomes a concave portion and the surface area is increased, so that the retention of the slurry is improved. .
[0056]
The reason why the polishing rate without the conditioning treatment is low is considered to be because the slurry is not retained in the surface layer.
[0057]
On the other hand, the polishing cloth of this embodiment has a large polishing rate of 205 nm / min even without conditioning treatment. This is because the water-soluble filler exposed on the surface of the polishing cloth is dissolved in water (slurry), and the area where the water-soluble filler was present becomes a concave portion and the surface area is increased, so that the retention of the slurry is improved. .
[0058]
The reason why the polishing rate without the conditioning treatment is low is considered to be because the slurry is not retained on the surface layer of the polishing pad.
[0059]
On the other hand, the polishing cloth of this embodiment has a large polishing rate of 205 nm / min even without conditioning treatment. This is because the water-soluble filler exposed on the surface of the polishing cloth is dissolved in water (slurry), and the area where the water-soluble filler was present becomes a concave portion and the surface area is increased, so that the retention of the slurry is improved. .
[0060]
In addition, the polishing cloth of this embodiment was obtained with a stable polishing rate. This is because the water-soluble filler 12 is exposed while the surface layer of the base material 11 is gradually worn during polishing, and the water-soluble filler 12 is melted by the slurry, and a new recess is formed.
[0061]
Further, when the polishing pad 10 was used while it was being conditioned, a polishing rate of 310 nm / min was obtained, which was much higher than that of the case where the polishing pad 10 was not conditioned and that of Polytex or the conventional polishing pad IC-1000.
[0062]
In addition, the dishing amount was evaluated using the sample shown in FIG. 3 as the material to be polished. In the sample, a silicon oxide film 22 having irregularities is formed on a Si substrate 21, and an Al film 23 is deposited on the entire surface of the silicon oxide film 22.
[0063]
The film thickness of the Al film 23 is 800 nm, the film thickness of the silicon oxide film 22 is 700 nm, and the height of the recess formed in the silicon oxide film 22 is 400 nm. Further, the relationship between the width A of the recess and the arrangement interval B of the recess was evaluated so that A / (A + B) was 0.7 and the width A of the recess was 10 μm and 100 μm.
[0064]
The evaluation was performed using the dishing amount when the Al film 23 was polished and the surface was polished to 23b.
[0065]
Table 2 shows the evaluation results of the dishing amount.
[0066]
[Table 2]

[0067]
The amount of dishing when polishing using a politex, which is a very soft polishing cloth, was 160 nm even at a wiring interval of 10 nm, and 350 nm or more at a wiring interval A of 100 nm.
[0068]
In addition, the amount of dishing when polishing is performed using a conventional polishing cloth IC-1000 that has been conditioned is 80 nm (A = 10 μm) and 210 nm (A = 100 μm), which is greater than when using a tex. Is improved, but still very large.
[0069]
Since a soft layer is formed on the surface layer of the IC-1000 by conditioning and adversely affects the flatness of the surface layer of the material to be polished during polishing, the amount of dishing is better when polishing is performed without conditioning. It will be smaller.
[0070]
However, the results are opposite, and the dishing amounts when polishing is performed without conditioning are 200 nm (A = 10 μm) and 250 nm (A = 100 μm), which are worse than those obtained when conditioning is performed.
[0071]
This is because if conditioning is not performed, deep scratches (> 200 nm) are formed on the surface of Al, and Al erosion proceeds in such a manner that the scratches expand.
[0072]
In response to these results, the dishing amount when polishing was performed using the polishing cloth 10 according to the embodiment of the present invention that was not conditioned was 8 nm when the interval A was 10 μm, and 100 μm when the interval A was 100 μm. The dishing is remarkably improved.
[0073]
The compression modulus of the base material itself is very hard as 10 GPa, and the soft layer of the surface layer does not cause scratches on the surface of the material to be polished, and the base material surface sufficiently holds the slurry. The dishing was improved because the thickness of the soft layer was controlled to be very thin.
[0074]
Moreover, the dishing amount at the time of grinding | polishing using the polishing cloth 10 in which the conditioning process was performed was 20 nm (A = 10 micrometer) and 80 nm (A = 100 micrometer).
[0075]
The dishing amount deteriorated because the softening layer on the surface of the polishing cloth became softer, the softening layer became thicker, or both.
[0076]
Next, the polishing rate for the Al film was evaluated by changing the particle size of the water-soluble filler 12. A polishing cloth was produced by fixing the concentration of the water-soluble filler to 25 wt% for all particle sizes. The results are shown in Table 3.
[0077]
[Table 3]

[0078]
From Table 3, it was confirmed that the polishing rate was changed according to the particle size of the water-soluble filler 12. When the particle size was 1 μm, many scratches were generated on the surface of the Al film as the material to be polished.
[0079]
This is because the particle size of the polishing cloth was too small, the irregularities formed on the surface of the polishing cloth were too fine, and a soft layer was not formed on the surface, and at the same time it was difficult to hold the slurry. is there.
[0080]
On the other hand, when the particle size is 50 μm and 100 μm, the polishing rate is slow. This is probably because the irregularities were too large. From the above results, it can be said that the particle size of the water-soluble filler is preferably about 5 to 30 μm.
[0081]
As described above, the polishing cloth of this embodiment is composed of a soft surface layer with irregularities formed thereon and a hard inner layer made of a base material and a solid water-soluble filler. Almost equal.
[0082]
Therefore, the soft surface layer with unevenness of the polishing cloth suppresses the improvement of the polishing rate and the formation of scratches on the surface layer of the material to be polished, and the flattening is improved by the hard layer inside the polishing cloth. Can do.
[0083]
In addition, the polishing cloth of the present invention has a stable polishing rate since a new water-soluble filler is exposed and dissolves in water or slurry even if the surface layer of the base material is scraped, and a soft layer always exists in the surface layer. Can be obtained.
[0084]
In addition, since the soft surface layer is automatically formed, almost no conditioning treatment is required, so the life of the polishing cloth is prolonged.
[0085]
(Second Embodiment)
FIG. 4 is a cross-sectional view showing the configuration of the polishing pad according to the second embodiment of the present invention.
[0086]
4 that are the same as those in FIG. 2 are assigned the same reference numerals, and detailed descriptions thereof are omitted.
[0087]
The feature of this embodiment is that the surface of the water-soluble filler 12 is coated with a coating layer 31 made of a material insoluble in water (slurry).
[0088]
When a large amount of water-soluble filler is mixed in the base material, the probability that the water-soluble fillers come into contact with each other increases. If the water-soluble fillers are in contact with each other and put on water, deep recesses 41 are formed as shown in FIG.
[0089]
However, as in this embodiment, the water-soluble filler 12 in contact with the coating layer is not completely dissolved by coating with the coating layer. Accordingly, it is possible to prevent a decrease in the elastic modulus due to the formation of the recesses deep inside the base material.
[0090]
The present invention is not limited to the above embodiment. For example, in the above embodiment, polystyrene is used as an example of the base material and cellulose is used as an example of the water-soluble filler. However, other materials can be used.
[0091]
Further, instead of the solid water-soluble filler, a liquid may be dispersed and mixed in the base material. The liquid is softer than the solid, but is sufficiently harder than the gas, and can be used instead of the water-soluble filler. Of course, since the liquid exposed on the surface flows out, a recess is formed in the area where the liquid was present, and the effect is similar to that of a solid water-soluble filler.
[0092]
Further, the fine particles mixed in the base material need only be soluble in other solvents as well as water-soluble. Before performing the polishing treatment, the concave portions may be formed by dissolving the fine particles by exposing the surface of the polishing cloth to a solvent capable of dissolving the fine particles.
[0093]
Next, an embodiment of a method for manufacturing a semiconductor device having a damascene wiring structure having a wiring groove using the polishing cloth will be described.
[0094]
FIG. 6 shows SiO ₂ A partial cross-sectional view of a damascene wiring structure in which an Al wiring 3 is embedded in a wiring groove 2 provided in the substrate 1 is shown.
[0095]
The depth of the wiring trench 2 is 4,000 mm (angstrom), the width is 100 μm, and the thickness of the Al layer of the Al wiring 3 before polishing is 8,000 mm (angstrom).
[0096]
With such a structure, when the Al wiring 3 is buried in the wiring groove 2 and the surface of the Al wiring 3 is polished with a polishing cloth from above, SiO 2 ₂ Overpolishing is performed even in a groove below the surface of the substrate 1, so-called dishing or thinning occurs.
[0097]
In this embodiment, the load is 300 g / cm. ² The flatness of the table and carrier was evaluated at 50 rpm. As a result, scratches on the Al wiring 3 embedded in the wiring groove 2 were evaluated by KLA. As a result, 42,328 / wafer were observed in the conventional polishing cloth IC-1000.
[0098]
On the other hand, in the polishing cloth of the present invention, only 320 / Wafer scratches were observed.
FIG. 7 shows that the occurrence of dishing in the polishing cloth of the present invention is remarkably improved as compared with the conventional polishing cloth.
[0099]
The number of dishing that occurs when the Al wiring 3 is polished using the conventional polishing cloth IC-1000 is such that over polishing reaches 60% of the depth of the groove as shown by the dotted line. It exceeds 3500Dishing.
[0100]
On the other hand, the polishing cloth containing fine particles dispersed inside the present invention is made of Al. ₂ O ₃ 3 wt%, (NH ₄ ) ₂ S ₂ O ₈ When the surface of the Al wiring 3 is polished by using a slurry in which a slurry containing 1 wt% of benztriazole and 0.02% of benztriazole is held on the surface, the number of dishing generated is indicated by a solid line Thus, even when over polishing reaches 60% of the depth of the groove, it hardly increases.
[0101]
This means that the quality and characteristics of the Al wiring 3 have been improved, and it can be said that the wiring was formed satisfactorily.
[0102]
FIG. 8 shows SiO ₂ A partial sectional view of a damascene wiring structure in which a Cu wiring 4 is embedded in a wiring groove 2 provided in the substrate 1 is shown.
[0103]
The depth of the wiring trench 2 is 4,000 mm (angstrom), the width is 100 μm, and the thickness of the Cu layer of the Cu wiring 4 before polishing is 8,000 mm (angstrom).
[0104]
FIG. 9 shows that the occurrence of dishing in the polishing cloth of the present invention is remarkably improved as compared with the conventional polishing cloth.
[0105]
The number of dishing that occurs when the Cu wiring 4 is polished using the conventional polishing cloth IC-1000 is such that over polishing reaches 60% of the depth of the groove as indicated by the dotted line. It reaches the vicinity of 3500Dishing (Å).
[0106]
On the other hand, the polishing cloth containing fine particles dispersed in the embodiment of the present invention is Al. ₂ O ₃ 1 wt%, (NH ₄ ) ₂ S ₂ O ₈ When the surface of the Cu wiring 4 is polished using a slurry in which 1 wt% of sol and 0.05% of benztriazole are held on the surface, the number of dishing generated is shown by a solid line Even when over polishing reaches 60% of the depth of the groove, it slightly increases.
[0107]
FIG. 10 shows SiO ₂ A partial cross-sectional view of a damascene wiring structure in which a W wiring layer 5 is embedded in a wiring groove 2 provided in a substrate 1 is shown.
[0108]
The depth of the wiring trench 2 is 4,000 mm (angstrom), the width is 100 μm, and the thickness of the W layer of the W wiring layer 5 before polishing is 8,000 mm (angstrom).
[0109]
FIG. 11 shows that the occurrence of dishing in the polishing cloth of the present invention is remarkably improved as compared with the conventional polishing cloth.
[0110]
Occurs when the W wiring 5 is polished using the conventional polishing cloth IC-1000.
As indicated by the dotted line, the number of dishing exceeds 3500 Dishing / Å when over polishing reaches 60% of the groove depth.
[0111]
On the other hand, the polishing cloth containing fine particles dispersed inside the present invention is made of Al. ₂ O ₃ 3 wt%, Fe (NO ₃ ) ₃ When the surface of the W wiring 5 is polished by using a slurry in which 5 wt% of slurry is held on the surface, the number of dishings generated is over-polishing as shown by the solid line. Even when it reaches 60% of the depth of the groove, it increases only slightly.
[0112]
Next, as another embodiment of the present invention, as shown in FIG. 12, an oxide film 6 having a thickness of 14,000 mm (angstrom) on a Si substrate 1 is formed with a depth of 7,000 mm (angstrom) and a width of It is buried in the 100 μm wiring groove 2 and the oxide film 6 is polished from the upper surface with the polishing cloth of the present invention. As the slurry at this time, a solution obtained by diluting Cabot SC-1 with pure water three times is used.
[0113]
As a result, as shown in FIG. 13, when the conventional polishing cloth IC-1000 is compared with the polishing cloth of the present invention, the same Oxide Removal amount angstrom is obtained. It can be seen that the Remaining Step amount Å is closer to the ideal curve for the polishing cloth of the present invention.
[0114]
Thereby, flattening without variation can be realized by polishing the surface of the oxide film using the polishing cloth of the present invention.
[0115]
In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.
[0116]
【The invention's effect】
As described above, according to the polishing cloth of the present invention, by dispersing and mixing fine particles soluble in a solvent into a base material for mechanically polishing the surface of a material to be polished, Since the fine particles dissolve in the solvent during polishing and form a recess on the surface of the polishing cloth, high planarization performance and a stable polishing speed are obtained on the surface layer of the material to be polished, and the surface of the material to be polished It is possible to suppress the occurrence of scratches in
[0117]
Also, a polishing cloth provided with a wiring groove on the substrate, metal wiring embedded in the wiring groove, and unnecessary portions of the metal wiring dispersed and mixed with fine particles soluble in a solvent in the base material The quality of the metal wiring (particularly, damascene wiring) can be improved by polishing and removing with.
[0118]
Furthermore, the semiconductor manufacturing method using the polishing cloth of the present invention provides a good surface of the oxide film by polishing with the polishing cloth of the present invention even when an oxide film is buried in the wiring groove instead of the metal wiring. Can be flattened.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of an ideal polishing cloth.
FIG. 2 is a partial cross-sectional view showing a configuration of a polishing cloth according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view partially showing a configuration of an object to be polished used for evaluation of a polishing cloth.
FIG. 4 is a partial cross-sectional view showing a configuration of a polishing cloth according to a second embodiment of the present invention.
FIG. 5 is a cross-sectional view of a polishing cloth for explaining a problem caused by contact between fine particles of the polishing cloth.
FIG. 6 is a fragmentary cross-sectional view showing the process of forming a semiconductor device when the metal wiring of the embedded wiring (damascene wiring) structure polished using the polishing cloth of the present invention is Al.
7 is a diagram when the occurrence of dishing when the metal wiring Al shown in FIG. 5 is polished using the polishing cloth of the present invention is compared with a conventional example.
FIG. 8 is a fragmentary cross-sectional view showing the process of forming a semiconductor device when the metal wiring of the embedded wiring (damascene wiring) structure polished using the polishing cloth of the present invention is Cu.
FIG. 9 is a view when the occurrence of dishing when the metal wiring Cu shown in FIG. 7 is polished using the polishing cloth of the present invention is compared with the conventional example.
FIG. 10 is a fragmentary cross-sectional view showing the process of forming a semiconductor device when the metal wiring of the embedded wiring (damascene wiring) structure polished using the polishing cloth of the present invention is W.
11 is a diagram in which the occurrence of dishing when the metal wiring W shown in FIG. 9 is polished using the polishing cloth of the present invention is compared with a conventional example.
FIG. 12 shows an application example related to a method for manufacturing a semiconductor device of the present invention, and shows a process of forming a semiconductor device for polishing an oxide film embedded in a groove provided in a substrate using the polishing cloth of the present invention. FIG.
FIG. 13 shows the value of Oxide Removal compared with the conventional example in the same remaining step / reduction when the oxide film shown in FIG. 10 is polished using the polishing cloth of the present invention. The figure which shows having improved.
[Explanation of symbols]
10 ... Polishing cloth
11 ... Base material
12 ... Water-soluble filler (fine particles)
31 ... Coating layer
1 ... SiO ₂ substrate
2. Wiring groove
3 ... Metal wiring Al
4 ... Metal wiring Cu
5 ... Metal wiring W
6 ... Oxide film

Claims (11)

A base material that holds the slurry on the surface and mechanically polishes the surface of the substrate to be treated;
A polishing cloth comprising fine particles dispersed in the base material, soluble in water and having a coating layer formed on the surface thereof insoluble in water . In the surface of the base material, when the surface of the substrate to be processed is mechanically polished, the fine particles present on the surface are dissolved in the water to form concave portions corresponding to the fine particles. The polishing cloth according to claim 1. Soluble in water, and a particulate coating layer is formed is insoluble in the water on its surface,
When the fine particles are dispersed inside and the surface of the material to be polished is mechanically polished, the slurry is held on the surface, and the fine particles present on the surface dissolve in the water and correspond to the fine particles on the surface. A polishing cloth comprising a base material on which a recess is formed. The abrasive cloth according to claim 1 or 3 , wherein the base material has no pores therein. The polishing cloth according to claim 1 or 3 , wherein the fine particles have a particle size of 5 to 30 µm. Forming an insulating film on the substrate, and then providing a wiring groove in the substrate through the insulating film;
Providing a metal wiring layer on the substrate and the wiring groove;
Burying metal wiring in the wiring groove;
A base material that holds the slurry on the surface and mechanically polishes the surface of the material to be polished, and is dispersed in the base material, is soluble in a solvent, and is insoluble in the solvent on the surface Polishing and removing unnecessary portions of the metal wiring embedded in the wiring groove with a polishing cloth made of fine particles on which a coating layer is formed, and planarizing the surface of the metal wiring. A method for manufacturing a semiconductor device using a polishing cloth.   7. The method of manufacturing a semiconductor device using an abrasive cloth according to claim 6, wherein the metal wiring is mainly composed of Al.   7. The method of manufacturing a semiconductor device using an abrasive cloth according to claim 6, wherein the metal wiring is mainly composed of Cu.   7. The method of manufacturing a semiconductor device using an abrasive cloth according to claim 6, wherein the metal wiring is mainly composed of W. Providing a groove in the substrate;
Providing an oxide film on the substrate, and burying the oxide film in the groove;
A base material that holds the slurry on the surface and mechanically polishes the surface of the material to be polished, and is dispersed in the base material, is soluble in a solvent, and is insoluble in the solvent on the surface. Polishing and removing unnecessary portions of the oxide film embedded in the groove with a polishing cloth made of fine particles on which the coating layer is formed, and planarizing the surface of the oxide film. A manufacturing method of a semiconductor device using a polishing cloth characterized by the above. The method of manufacturing a semiconductor device using a polishing pad according to claim 10, wherein the oxide film is SiO ₂ .

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