JP2018167388A - Polishing pad - Google Patents
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- JP2018167388A JP2018167388A JP2017069360A JP2017069360A JP2018167388A JP 2018167388 A JP2018167388 A JP 2018167388A JP 2017069360 A JP2017069360 A JP 2017069360A JP 2017069360 A JP2017069360 A JP 2017069360A JP 2018167388 A JP2018167388 A JP 2018167388A
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- polishing pad
- polyurethane resin
- cellulose
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Abstract
Description
本発明は、研磨パッドに係り、特に、湿式成膜により形成されたポリウレタン発泡シートを研磨層として有する研磨パッドに関する。 The present invention relates to a polishing pad, and more particularly to a polishing pad having a polyurethane foam sheet formed by wet film formation as a polishing layer.
半導体ウェハ上にパターニングされた集積回路は微細化・高密度化が進められており、それらの配線構造を実現化するためにより低い誘電率を有する絶縁材料（low-k及び超low-k絶縁体）と銅配線の使用が進められている。このような半導体デバイス等では、表面の平坦化のための研磨加工時に、low-k及び超low-k絶縁体が従来使用されていた絶縁体よりも機械的強度が低いうえ付着力も弱いため、ディフェクト（欠陥）が生じ易いという問題がある。また、配線構造の高密度化によりディッシング・エロージョン等の平坦化特性も厳密なレベルが要求される。このような半導体デバイスやその前駆体、及び、半導体デバイス形成後の裏面研磨等の研磨加工では、発泡ポリウレタン系パッド、不織布系パッド、スエード系パッド等の研磨パッドが用いられている。中でも、スエード系パッドと呼ばれる湿式成膜法によるポリウレタン樹脂等の軟質プラスチック発泡シートを研磨層として有する研磨パッドは、例えば、特許文献１に記載の如く、研磨面から厚み方向に遠ざかるにつれて拡大する発泡を有するため、研磨パッドの圧縮率が大きく、また、多孔質状となっているため軟質となり、特に研磨傷の発生を抑える点で好適に用いられている。 Integrated circuits patterned on semiconductor wafers are being miniaturized and densified, and insulating materials with lower dielectric constants (low-k and ultra-low-k insulators) to realize their wiring structure ) And copper wiring are being used. In such semiconductor devices, low-k and ultra-low-k insulators have lower mechanical strength and weaker adhesion than conventional insulators when polishing to flatten the surface. There is a problem that defects are likely to occur. In addition, due to the high density of the wiring structure, a strict level is required for flattening characteristics such as dishing and erosion. Polishing pads such as foamed polyurethane pads, non-woven pads, and suede pads are used in such polishing processes such as semiconductor devices and their precursors and backside polishing after the semiconductor devices are formed. Among them, a polishing pad having a soft plastic foamed sheet such as a polyurethane resin by a wet film forming method called a suede-based pad as a polishing layer is, for example, a foam which expands as it moves away from the polishing surface in the thickness direction as described in Patent Document 1, for example Therefore, the polishing pad has a large compressibility, and since it is porous, it becomes soft, and is particularly preferably used in terms of suppressing the occurrence of polishing flaws.
こうした湿式成膜法による研磨パッドでは、ポリウレタン樹脂の発泡状態の調整や、強度の向上、粘弾性の調整のため、通常、その樹脂溶液にカーボンブラックが添加されている。カーボンブラックの添加が、ポリウレタン樹脂溶媒と水の置換を促進して発泡を成長させ、また、成膜後の発泡シートの強度を向上させ、被研磨物の表面を高精度に平坦化し得る研磨均一性の向上に寄与する。 In a polishing pad by such a wet film forming method, carbon black is usually added to the resin solution for adjusting the foamed state of the polyurethane resin, improving the strength, and adjusting the viscoelasticity. Addition of carbon black accelerates the substitution of polyurethane resin solvent and water, grows foam, improves the strength of the foamed sheet after film formation, and evenly polishes the surface of the object to be polished with high precision Contributes to the improvement of sex.
しかしながら、特許文献１に記載の如くにカーボンブラックを添加したポリウレタン樹脂溶液を湿式成膜して得られる研磨パッドは、研磨パッドに好適な発泡状態が得られたとしても、ウレタン樹脂組成物中にカーボンブラックの大きな凝集体が生成されることで、被研磨物に傷を与える原因となってしまう。そこで、特許文献１では、カーボンブラックとともに特定のアニオン性界面活性剤を使用することでカーボンブラックの凝集を抑制しているが、研磨パッド内部に残存した界面活性剤が研磨中に溶出することで、被研磨物を汚染したり、スラリー成分と結合し研磨傷の原因となる場合がある。 However, as described in Patent Document 1, a polishing pad obtained by wet-forming a polyurethane resin solution to which carbon black has been added is included in the urethane resin composition even if a foaming state suitable for the polishing pad is obtained. The generation of large aggregates of carbon black causes damage to the object to be polished. Therefore, in Patent Document 1, although a specific anionic surfactant is used together with carbon black to suppress the aggregation of carbon black, the surfactant remaining inside the polishing pad is eluted during polishing. In some cases, the object to be polished is contaminated or bonded to the slurry component to cause polishing scratches.
本発明の課題は、研磨パッドにおいて、被研磨物に対する研磨傷の発生を抑制しながら、被研磨物の表面を平坦化し得る研磨均一性の向上を図ることにある。 An object of the present invention is to improve the polishing uniformity capable of flattening the surface of an object to be polished while suppressing the generation of polishing scratches on the object to be polished in the polishing pad.
請求項１に係る発明は、湿式成膜法により形成される複数の涙形発泡を内在するポリウレタン発泡シートを研磨層として有する研磨パッドであって、研磨層が、比表面積１０乃至５００m2/gの微小繊維を含むようにしたものである。 The invention according to claim 1 is a polishing pad having, as a polishing layer, a polyurethane foam sheet containing a plurality of tear-shaped foams formed by a wet film forming method, wherein the polishing layer has a specific surface area of 10 to 500 m 2 / g. The microfiber is included.
請求項２に係る発明は、請求項１に係る発明において更に、前記微小繊維は、繊維径１乃至１０００nm、繊維長１００nm乃至１００μmである。 The invention according to claim 2 is the invention according to claim 1, wherein the microfibers have a fiber diameter of 1 to 1000 nm and a fiber length of 100 nm to 100 μm.
請求項３に係る発明は、請求項１又は２に係る発明において更に、前記微小繊維がセルロースから得られる微小繊維であるようにしたものである。 The invention according to claim 3 is the invention according to claim 1 or 2, wherein the microfiber is a microfiber obtained from cellulose.
本発明によれば、研磨パッドにおいて、被研磨物に対する研磨傷の発生を抑制しながら、被研磨物の表面を平坦化し得る研磨均一性の向上を図ることができる。 ADVANTAGE OF THE INVENTION According to this invention, the polishing uniformity which can planarize the surface of a to-be-polished object can be aimed at, suppressing generation | occurrence | production of the polishing flaw with respect to a to-be-polished object in a polishing pad.
１．研磨パッドの構成
本発明の研磨パッドは、ポリウレタン発泡シートを研磨層として有する。研磨層は、比表面積１０乃至５００m2/gの微小繊維を添加したポリウレタン樹脂溶液を湿式成膜して得られる。
1. Configuration of Polishing Pad The polishing pad of the present invention has a polyurethane foam sheet as a polishing layer. The polishing layer is obtained by wet-forming a polyurethane resin solution to which fine fibers having a specific surface area of 10 to 500 m 2 / g are added.
(a)ポリウレタン発泡シートからなる研磨層の形成に際し、微小繊維は、ナノメートルオーダー（極小サイズ）であることから、少量の添加でもポリウレタン樹脂中における樹脂単位体積あたりの構成本数を向上させることができ、また、比表面積が１０乃至５００m2/gと大きいことから凝固再生のスピードを調整し、発泡の形状を調整することができる。 (a) When forming a polishing layer made of a polyurethane foam sheet, since the microfibers are on the nanometer order (minimum size), the addition of a small amount can improve the number of constituents per unit volume of the polyurethane resin. In addition, since the specific surface area is as large as 10 to 500 m 2 / g, the speed of solidification regeneration can be adjusted, and the foam shape can be adjusted.
即ち、ポリウレタン発泡シートからなる研磨層は、比表面積が１０乃至５００m2/gでナノメートルオーダー（極小サイズ）の太さを有する微小繊維を均一に分散させたポリウレタン樹脂溶液の湿式凝固により、ポリウレタン樹脂自体が略涙形状の発泡（以下、涙形発泡という）を有する多孔質構造を安定して形成できると同時に、この涙形発泡の周辺に直径１０乃至４０μm程度の多数の微細発泡を該シート全体に形成する。微細発泡形成のメカニズムは詳しく分かっていないが、ポリウレタン発泡シート中の各所に均一に分散されている微小繊維が高い比表面積を有するため、凝集核剤として繊維表面と樹脂が作用する箇所が増え、微小繊維の表面からも局所的にポリウレタン樹脂の凝固が進行し易くなるとともに、それら各所における凝固スピードにずれが生じ、それら各所における微小繊維の近傍に微細発泡が形成されるものと推測される。従って、研磨層は、研磨に適した涙形発泡と直径５乃至４０μm程度の微細発泡を有することができ、研磨均一性を向上、及び、研磨後の被研磨物の平坦性を向上させることができる。 That is, the polishing layer made of a polyurethane foam sheet is obtained by wet coagulation of a polyurethane resin solution in which fine fibers having a specific surface area of 10 to 500 m 2 / g and a nanometer order (minimum size) thickness are uniformly dispersed. The resin itself can stably form a porous structure having a generally tear-shaped foam (hereinafter referred to as a tear-shaped foam), and at the same time, a large number of fine foams having a diameter of about 10 to 40 μm are formed around the tear-shaped foam. Form the whole. The mechanism of fine foam formation is not known in detail, but because the microfibers that are uniformly dispersed in various places in the polyurethane foam sheet have a high specific surface area, the number of places where the fiber surface and the resin act as an agglomerating nucleating agent increases, It is presumed that coagulation of the polyurethane resin is likely to proceed locally from the surface of the microfibers, and the coagulation speed is shifted at each of these locations, so that fine foam is formed in the vicinity of the microfibers at these locations. Therefore, the polishing layer can have a teardrop-shaped foam suitable for polishing and a fine foam having a diameter of about 5 to 40 μm to improve the polishing uniformity and the flatness of the polished object after polishing. it can.
微小繊維の比表面積が１０m2/g以上の場合には、凝固スピードのずれが生じ、所望の微細発泡が形成され易くなる。比表面積が５００m2/g以内の場合には、微小繊維ポリウレタン樹脂中で微小繊維の凝集を起こすことなく、発泡形状を調整する効果を得ることができるため好ましい。 When the specific surface area of the microfiber is 10 m 2 / g or more, a deviation in coagulation speed occurs, and a desired fine foam is easily formed. A specific surface area of 500 m 2 / g or less is preferable because the effect of adjusting the foam shape can be obtained without causing aggregation of the microfibers in the microfiber polyurethane resin.
微小繊維の比表面積は、例えば窒素ガス吸着法により測定することができる。より具体的には、微小繊維の水分散液を遠心分離により上澄みをデカンテーションして取り除き、残渣をｔ-ブチルアルコール（t-butyl alcohol）に再度分散させ、遠心分離し上澄みを取り除いた。この操作を５回繰り返し溶媒置換後、凍結乾燥処理し、自動比表面積／細孔径分布測定装置を用いた窒素ガス吸着法によりＢＥＴ比表面積を測定する。 The specific surface area of the microfiber can be measured, for example, by a nitrogen gas adsorption method. More specifically, the supernatant was removed by decantation of the aqueous dispersion of microfibers by centrifugation, the residue was dispersed again in t-butyl alcohol, and centrifuged to remove the supernatant. This operation is repeated 5 times, followed by solvent replacement, freeze-drying, and the BET specific surface area is measured by a nitrogen gas adsorption method using an automatic specific surface area / pore size distribution measuring apparatus.
ポリウレタン発泡シートより微小繊維の比表面積を確認する場合、シートをＤＭＦにより溶解させ、固形分をＤＭＦに分散させ、上述のようにｔ-ブチルアルコール溶媒置換後、凍結乾燥し、比表面積を測定することができる。 When confirming the specific surface area of the microfibers from the polyurethane foam sheet, the sheet is dissolved with DMF, the solid content is dispersed in DMF, and after substitution with a t-butyl alcohol solvent as described above, lyophilized and the specific surface area is measured. be able to.
また、簡易的に比表面積を平均繊維径より換算して求めることもできる。円柱モデルを想定した場合の比表面積ＳＡ（m2/g）は、平均繊維径をＤ（μm）、繊維長をＬ（μm）、密度をρ（g/cm3）とすると、ＳＡ＝（２πＤ2／４＋ＤπＬ）／（π（Ｄ／２）2Ｌρ）であり、ここで、アスペクト比Ａｒ＝Ｌ／Ｄとすれば、ＳＡ＝（２／Ａｒ＋４）／Ｄρとなり、４＞＞２／Ａｒであるので、ＳＡ≒４／Ｄρとなる。例えば、微小繊維がセルロースの場合、密度を１．５０g/cm3として、その比表面積（m2/g）はＳＡ（m2/g）＝２．６７／平均繊維径（nm）×１０００として求めることができる。平均繊維径（繊維径の平均値）は、電子顕微鏡の視野内の微小繊維の少なくとも５０本以上について測定したときの平均値とする。電子顕微鏡としては、電解放出型走査電子顕微鏡（ＦＥ-ＳＥＭ）、透過型電子顕微鏡（ＴＥＭ）、走査電子顕微鏡（ＳＥＭ）等により繊維径を確認することができる。 Further, the specific surface area can be simply calculated from the average fiber diameter. The specific surface area SA (m 2 / g) in the case of assuming a cylindrical model is SA = (where the average fiber diameter is D (μm), the fiber length is L (μm), and the density is ρ (g / cm 3 ). 2πD 2/4 + DπL) a / (π (D / 2) 2 Lρ), wherein, if the aspect ratio Ar = L / D, SA = (2 / Ar + 4) / Dρ next, 4 >> 2 / Ar Therefore, SA≈4 / Dρ. For example, when the microfiber is cellulose, the density is 1.50 g / cm 3 and the specific surface area (m 2 / g) is SA (m 2 /g)=2.67/average fiber diameter (nm) × 1000. Can be sought. The average fiber diameter (average fiber diameter) is the average value when measuring at least 50 fine fibers in the field of view of the electron microscope. As the electron microscope, the fiber diameter can be confirmed by an electrolytic emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), a scanning electron microscope (SEM), or the like.
(b)ポリウレタン発泡シートからなる研磨層は、比表面積が１０乃至５００m2/gの微小繊維を添加し、ポリウレタン樹脂中に均一に分散されることから、カーボンブラックを使用せずとも略均一な形状の発泡が安定して形成され（成膜安定性の向上）、ひいては被研磨物の表面を安定して高精度に平坦化でき、研磨傷の発生を低減し研磨均一性を向上できる。 (b) The polishing layer made of a polyurethane foam sheet is added with fine fibers having a specific surface area of 10 to 500 m 2 / g, and is uniformly dispersed in the polyurethane resin, so that it is substantially uniform without using carbon black. Foam having a shape is stably formed (improvement of film formation stability), and the surface of the object to be polished can be stably flattened with high accuracy, and generation of polishing flaws can be reduced and polishing uniformity can be improved.
(c)ポリウレタン発泡シートからなる研磨層は、多数の涙形発泡と多数の略球状微細発泡を有する多孔質構造からなる。涙形発泡と略球状微細発泡は、通常、両者の発泡を網目状に連通する連続発泡構造を形成する。本発明のポリウレタン発泡シートは、従来のポリウレタン発泡シートに比べ、発泡径５乃至４０μm程度の断面略球状の微細発泡のうち１０μm〜４０μmの大きな微細発泡の含有率が増す。微細発泡のサイズが大きいため、研磨面に開口するこれらの涙形発泡及び微細発泡に研磨スラリーを速やかに保持し、研磨面直下の領域に研磨スラリーをより多く蓄えることができる。これにより、研磨面に十分な量のスラリーを保持することができるため、研磨パッドの立ち上がり処理時間を短縮することができる。 (c) The polishing layer made of the polyurethane foam sheet has a porous structure having many tear-shaped foams and many substantially spherical fine foams. The tear-shaped foam and the substantially spherical fine foam usually form a continuous foam structure in which both foams are communicated in a network. Compared with the conventional polyurethane foam sheet, the polyurethane foam sheet of the present invention has an increased content of fine foam of 10 to 40 μm among the fine foam having a substantially spherical cross section with a foam diameter of about 5 to 40 μm. Since the size of the fine foam is large, it is possible to quickly hold the polishing slurry in these teardrop-shaped foam and fine foam opening on the polishing surface, and to store more polishing slurry in the region directly under the polishing surface. As a result, a sufficient amount of slurry can be held on the polishing surface, so that the polishing pad rising processing time can be shortened.
またこのとき、スラリーを保持する涙形発泡及び微細発泡が研磨面直下の広い範囲の全体に渡って略均等に形成され、このことが被研磨物の表面を安定して高精度に平坦化し、研磨均一性の向上に寄与する。 Further, at this time, the tear-shaped foam and fine foam holding the slurry are formed substantially uniformly over the entire wide area immediately below the polishing surface, and this stably and accurately flattens the surface of the object to be polished, Contributes to improved polishing uniformity.
(d)本発明に使用される微小繊維は、繊維径１乃至１０００nm、であることが好ましく、繊維径５乃至８００nmであることがより好ましく、繊維径１０乃至５００nmであることが更に好ましい。微小繊維は繊維径がナノメートルオーダー（極小サイズ）であって、ポリウレタン樹脂に添加して湿式成膜するときに偏在し難く、良好に分散して凝集しにくいため、研磨パッドの硬質成分とならずに、被研磨物に対し研磨傷の要因とならない。 (d) The fine fiber used in the present invention preferably has a fiber diameter of 1 to 1000 nm, more preferably a fiber diameter of 5 to 800 nm, and still more preferably a fiber diameter of 10 to 500 nm. Microfibers have a fiber diameter of the order of nanometers (very small size) and are not unevenly distributed when added to polyurethane resin for wet film formation. In addition, it does not cause polishing scratches on the workpiece.
微小繊維はポリウレタン樹脂の溶媒（ＤＭＦ）に分散させてポリウレタン樹脂溶液に混合させる。 The microfibers are dispersed in a polyurethane resin solvent (DMF) and mixed with the polyurethane resin solution.
微小繊維の原料は、例えば、デンプン（アミロース及びアミロペクチン）、グリコーゲン、セルロース、キチン、キトサン、アガロース、カラギーナン、ヘパリン、ヒアルロン酸、ペクチン、キシログルカン等の多糖類を上げることができる。これらの中でも、強度の大きな微小繊維を得ることのできるセルロース、及び、キチン、キトサンを原料として使用することがより好ましい。 Examples of the raw material for the fine fibers include polysaccharides such as starch (amylose and amylopectin), glycogen, cellulose, chitin, chitosan, agarose, carrageenan, heparin, hyaluronic acid, pectin, and xyloglucan. Among these, it is more preferable to use cellulose, chitin and chitosan as raw materials from which high-strength microfibers can be obtained.
微小繊維の製造方法としては電解紡糸、溶融紡糸、メルトブロー、遠心紡糸、フラッシュ紡糸等の紡糸によるものや、繊維質や繊維束（例えば、パルプ）を物理的解繊、化学的解繊等解繊によるもの等が挙げられる。 Microfiber production methods include electrospinning, melt spinning, meltblowing, centrifugal spinning, flash spinning, etc., and fiber and fiber bundles (for example, pulp) are physically and chemically defibrated. And the like.
２．微小繊維の具体的態様
(a)好ましい微小繊維
多糖類から得られる微小繊維の形態としては、微小繊維状のセルロース、キチン、キトサン、セルロース、キチン、キトサンの微結晶、微小繊維状リグノセルロース、バクテリアセルロースが挙げられる。この中でも微小繊維状セルロースがより好ましい。
2. Specific embodiment of microfiber
(a) Preferred microfibers Examples of the microfibers obtained from the polysaccharide include microfibrous cellulose, chitin, chitosan, cellulose, chitin, chitosan microcrystals, microfibrous lignocellulose, and bacterial cellulose. Among these, microfibrous cellulose is more preferable.
(b)微小繊維状セルロースの製造方法
微小繊維状セルロースの製造方法としては高圧ホモジナイザー法、水中カウンターコリジョン法、グラインダー法、ボールミル法、２軸混練法等の物理的解繊によるもの、物理的解繊の前処理としてＴＥＭＰＯ触媒による化学処理を行う方法等、公知の方法により得られたものを使用することができる。
(b) Production method of microfibrous cellulose The production method of microfibrous cellulose includes high-pressure homogenizer method, underwater counter collision method, grinder method, ball mill method, biaxial kneading method, etc. What was obtained by well-known methods, such as the method of performing the chemical treatment by a TEMPO catalyst as pretreatment of textiles, can be used.
微小繊維状セルロースの繊維径は３乃至１０００nm、繊維長１００乃至１０００００nmが好ましい。この範囲であればポリウレタン樹脂中に微小繊維状セルロースを均一に分散させることができる。アスペクト比は１０乃至１００００であることが好ましい。この範囲であれば、均一に分散した微小繊維が水酸基とポリウレタン樹脂の水素結合等により、ポリウレタン発泡シートの強度を向上させることができる。 The fiber diameter of the microfibrous cellulose is preferably 3 to 1000 nm and the fiber length is 100 to 100,000 nm. Within this range, the fine fibrous cellulose can be uniformly dispersed in the polyurethane resin. The aspect ratio is preferably 10 to 10,000. If it is this range, the intensity | strength of a polyurethane foam sheet can be improved according to the hydrogen bond etc. of a hydroxyl group and a polyurethane resin by the fine fiber disperse | distributed uniformly.
(c)微小繊維状セルロースの特性
天然セルロース繊維は、セルロースミクロフィブリル束とその間を埋めているリグニン及びヘミセルロースから構成された構造を有する。即ち、セルロースミクロフィブリル及び／又はセルロースミクロフィブリル束の周囲をヘミセルロースが覆い、更にこれをリグニンが覆った構造を有していると推測される。リグニンによってセルロースミクロフィブリル及び／又はセルロースミクロフィブリル束間は、強固に接着しており、植物繊維を形成している。そのため、植物繊維中のリグニンは予め除去されていることが、植物繊維中のセルロース繊維の凝集を防ぐことができるという点で好ましい。具体的には、植物繊維含有材料中のリグニン含有量は、通常４０質量％程度以下、好ましくは１０質量％程度以下である。また、リグニンの除去率の下限は、特に限定されるものではなく、０質量％に近いほど好ましい。
(c) Characteristics of microfibrous cellulose Natural cellulose fibers have a structure composed of cellulose microfibril bundles and lignin and hemicellulose filling them. That is, it is presumed that hemicellulose covers a cellulose microfibril and / or cellulose microfibril bundle, and further has a structure in which this is covered with lignin. Cellulose microfibrils and / or cellulose microfibril bundles are firmly bonded by lignin to form plant fibers. Therefore, it is preferable that lignin in the plant fiber is removed in advance from the viewpoint that aggregation of the cellulose fiber in the plant fiber can be prevented. Specifically, the lignin content in the plant fiber-containing material is usually about 40% by mass or less, preferably about 10% by mass or less. Further, the lower limit of the lignin removal rate is not particularly limited, and it is preferably as close to 0% by mass.
微小繊維状セルロースは、セルロース繊維の最小単位であるセルロースミクロフィブリルを複数本、例えば数十本の束で使用される。好ましい微小繊維状セルロースの繊維径（長さ方向と直交する方向の寸法であり、１本の場合には直径、複数本束の場合には束の径に相当）は、１乃至１０００nm（複数本束にされた場合の幅を含む）である。特に微小繊維状セルロースの入手容易性を考慮すると、微小繊維状セルロースのより好ましい幅は１乃至３００nmであることができ、更に１nm乃至１５０nmであることができ、特に１nm乃至１００nmであることができる。尚、通常のセルロース繊維は、直径が１０乃至５０μm程度（マイクロメートルオーダー）であり、本発明で使用する微小繊維状セルロースとは１０３レベルのオーダー差がある。また、本発明で使用する微小繊維状セルロースのアスペクト比（繊維長／繊維径）は、平均値で、１０乃至１００００であることができ、更に１０乃至１０００であることができ、特に１００乃至５００であることができる。尚、微小繊維状セルロースの繊維径及び繊維長の平均値は、電子顕微鏡の視野内の微小繊維状セルロースの少なくとも５０本以上について測定した算術平均値である。 The microfibrous cellulose is used in a bundle of a plurality of, for example, several tens of cellulose microfibrils, which are the smallest unit of cellulose fibers. The fiber diameter of the preferred microfibrous cellulose (the dimension in the direction perpendicular to the length direction, corresponding to the diameter in the case of one and the diameter of the bundle in the case of multiple bundles) is 1 to 1000 nm (multiple Including the width when bundled). Considering the availability of microfibrous cellulose in particular, a more preferable width of microfibrous cellulose can be 1 to 300 nm, further 1 nm to 150 nm, and particularly 1 nm to 100 nm. . In addition, a normal cellulose fiber has a diameter of about 10 to 50 μm (micrometer order), and has an order difference of 10 3 level from the microfibrous cellulose used in the present invention. The aspect ratio (fiber length / fiber diameter) of the microfibrous cellulose used in the present invention can be an average value of 10 to 10,000, more preferably 10 to 1000, and particularly 100 to 500. Can be. In addition, the average value of the fiber diameter and fiber length of a microfibrous cellulose is an arithmetic average value measured about at least 50 or more microfibrous cellulose within the visual field of an electron microscope.
微小繊維状セルロースは、ナノメートルオーダーであることから、少量の添加でもポリウレタン樹脂中に分散し樹脂単位体積あたりの微小繊維本数を向上させることができるため、ポリウレタン発泡シートの剛性の向上に併せ、耐摩耗性を向上させることができる。添加量を多くすれば、耐摩耗性の更なる向上が期待できる。しかし、微小繊維状セルロースの添加は、原料粘度を増加させるため、多量に添加した場合には、分散不良を引き起こし、ひいては発泡バランスが崩れるおそれがある。そのため、前記微小繊維状セルロースの好ましい添加量は、ポリウレタン発泡シートの全質量に対し、０．１乃至１０質量％、より好ましくは０．１５乃至５質量％である。更に、樹脂溶媒が多量に添加される湿式凝固法は、原料配合液の粘度を低くできる一方、微小繊維状セルロースの添加を容易にし、原料配合液中の微小繊維状セルロースの分散を良好にすることができる。更に、凝固再生後の乾燥工程により、分散した微小繊維状セルロースが水素結合によりウレタン樹脂とネットワークを形成し、ポリウレタン発泡シートの剛性を著しく向上させるため本発明のポリウレタン発泡シートは、湿式凝固法によって製造されたものが好ましい。微小繊維あるいは極細繊維を交絡して繊維と繊維を密に絡め合せ繊維を一体化させて得られる不織布や織物・編物にポリウレタン樹脂を含浸させたシートでは、微小繊維がポリウレタン樹脂中で流動し均一に分散することができないため好ましくない。 Since the microfibrous cellulose is on the order of nanometers, it can be dispersed in a polyurethane resin even with a small amount of addition and the number of microfibers per unit volume of the resin can be improved. Abrasion resistance can be improved. If the amount added is increased, further improvement in wear resistance can be expected. However, the addition of microfibrous cellulose increases the viscosity of the raw material, so when added in a large amount, it may cause a dispersion failure and consequently the foaming balance may be lost. Therefore, the preferable addition amount of the microfibrous cellulose is 0.1 to 10% by mass, more preferably 0.15 to 5% by mass with respect to the total mass of the polyurethane foam sheet. Furthermore, the wet coagulation method in which a large amount of the resin solvent is added can lower the viscosity of the raw material mixture liquid, while facilitating the addition of the microfibrous cellulose and improving the dispersion of the microfibrous cellulose in the raw material mixture liquid. be able to. Furthermore, since the dispersed microfibrous cellulose forms a network with the urethane resin by hydrogen bonding in the drying step after the coagulation regeneration, the polyurethane foam sheet of the present invention is remarkably improved by the wet coagulation method. Those produced are preferred. In a sheet in which a polyurethane resin is impregnated with a nonwoven fabric, woven fabric or knitted fabric obtained by entanglement of fine fibers or ultrafine fibers and tightly entwining the fibers to each other, the microfibers flow uniformly in the polyurethane resin. It is not preferable because it cannot be dispersed in the water.
３．研磨パッドの製造方法
本発明の研磨パッドは、湿式成膜法、例えば、ポリウレタン樹脂、Ｎ，Ｎ−ジメチルホルムアミド（ＤＭＦ）、及び微小繊維を混合分散させたポリウレタン樹脂溶液を調製する工程と、ポリウレタン樹脂溶液を基材に塗布する工程と、ポリウレタン樹脂溶液が塗布された基材を凝固液に浸漬するポリウレタン樹脂の凝固再生工程とを含む方法により、製造することができる。
3. Manufacturing method of polishing pad The polishing pad of the present invention comprises a wet film forming method, for example, a step of preparing a polyurethane resin solution in which a polyurethane resin, N, N-dimethylformamide (DMF), and microfibers are mixed and dispersed, and a polyurethane. It can be produced by a method including a step of applying a resin solution to a substrate and a step of coagulating and regenerating the polyurethane resin in which the substrate coated with the polyurethane resin solution is immersed in a coagulation liquid.
(1)ポリウレタン樹脂溶液を調製する工程
ポリウレタン樹脂溶液中のウレタン樹脂の濃度は、例えば、１０乃至５０質量％、好ましくは２０乃至４０質量％である。この濃度範囲であれば、シート密度が適切な範囲に調整され、所望の発泡構造を形成することができる。
(1) Step of preparing polyurethane resin solution The concentration of the urethane resin in the polyurethane resin solution is, for example, 10 to 50% by mass, preferably 20 to 40% by mass. Within this concentration range, the sheet density is adjusted to an appropriate range, and a desired foam structure can be formed.
ii.ポリウレタン樹脂の良溶媒であるＤＭＦは、水に対して任意の割合で混合することができるため、凝固液（水）との置換速度が速く、ポリウレタン樹脂溶液の下層（基材の側）の一部の樹脂分が上層（表面層）の側へ移動し、下層の側に比較的大きな発泡（シート厚さ方向に縦長をなす発泡）を形成し易い。 ii. DMF, which is a good solvent for polyurethane resin, can be mixed at an arbitrary ratio with respect to water, so the replacement speed with the coagulation liquid (water) is fast, and the lower layer (base material side) of the polyurethane resin solution A part of the resin moves to the upper layer (surface layer) side, and relatively large foaming (foaming vertically long in the sheet thickness direction) is easily formed on the lower layer side.
iii.本発明の研磨パッドに添加する微小繊維状セルロースは、ポリウレタン樹脂溶媒のＤＭＦに分散させてポリウレタン樹脂溶液に混合させる。ＤＭＦへの分散性を高めるため微小繊維状セルロースは化学修飾されていても分散剤を添加していても良い。本発明において、微小繊維状セルロースは、パルプや木材等の原料を解繊及び／又は微細化して微小繊維状セルロースを製造した後、修飾する化合物を更に添加して、微小繊維状セルロースと反応させることで得られる微小繊維状変性セルロースであっても良い。或いは、原料をまず化学修飾した後に、解繊処理を行うことで得られる微小繊維状変性セルロースであっても良い。修飾する化合物としては、アルキル基、アシル基、アシルアミノ基、シアノ基、アルコキシ基、アリール基、アミノ基、アリールオキシ基、シリル基、カルボキシル基等の官能基が挙げられ、微小繊維状セルロースに前記官能基を化学的に結合させることにより微小繊維状変性セルロースが得られる。 iii. The fine fibrous cellulose to be added to the polishing pad of the present invention is dispersed in a polyurethane resin solvent DMF and mixed with the polyurethane resin solution. In order to improve the dispersibility in DMF, the microfibrous cellulose may be chemically modified or a dispersant may be added. In the present invention, the microfibrous cellulose is produced by defibrating and / or refining raw materials such as pulp and wood to produce the microfibrous cellulose, and further adding a modifying compound to react with the microfibrous cellulose. The fine fibrous modified cellulose obtained by this may be sufficient. Alternatively, it may be a microfibrous modified cellulose obtained by first chemically modifying the raw material and then performing a defibrating treatment. Examples of the modifying compound include functional groups such as an alkyl group, an acyl group, an acylamino group, a cyano group, an alkoxy group, an aryl group, an amino group, an aryloxy group, a silyl group, and a carboxyl group. A fine fibrous modified cellulose can be obtained by chemically bonding a functional group.
iv.ポリウレタン樹脂溶液は、必要に応じて、更に添加剤を含んでいても良い。添加剤としては、特に制限されないが、ポリウレタン樹脂の凝固再生工程で、ポリウレタン樹脂の凝固速度を調整して所望の発泡形状を形成する点から、カーボンブラック等の顔料、疎水性活性剤、親水性活性剤が好ましい。これらの添加剤は、単独で又は２種以上組み合わせて使用できる。添加剤の配合量は、特に制限されず、ウレタン樹脂含有溶液１００質量部に対して、例えば、２０質量部以下、好ましくは例えば、１乃至１５質量部である。しかし、ディフェクト発生の要因となり得るカーボンブラック等の添加剤は特に研磨傷が問題となる研磨工程においては使用量を減じるか、使用しないことが好ましい。要求品質に対し研磨傷が問題とならないレベルである場合には、カーボンブラックを添加しても良い。また、界面活性剤は被研磨物を汚染やスラリーとの凝集が問題とならないものを選択して使用する。 iv. The polyurethane resin solution may further contain an additive as necessary. The additive is not particularly limited, but in the process of solidifying and regenerating the polyurethane resin, the solidification rate of the polyurethane resin is adjusted to form a desired foamed shape, so that a pigment such as carbon black, a hydrophobic active agent, a hydrophilic property An activator is preferred. These additives can be used alone or in combination of two or more. The compounding amount of the additive is not particularly limited, and is, for example, 20 parts by mass or less, preferably, for example, 1 to 15 parts by mass with respect to 100 parts by mass of the urethane resin-containing solution. However, it is preferable to reduce or not use additives such as carbon black that can cause defects, particularly in a polishing process in which polishing scratches are a problem. Carbon black may be added when the level of polishing scratches is not a problem for the required quality. Further, a surfactant that does not cause a problem of contamination or aggregation with the slurry is selected and used.
(2)ポリウレタン樹脂溶液の塗布工程
ポリウレタン樹脂溶液の塗布工程で用いる基材は、可撓性を有する材料であれば良く、例えば、プラスチックフィルム（ポリエステルフィルム、ポリオレフィンフィルム等）、不織布等が挙げられる。基材にポリウレタン樹脂含有溶液を塗布する方法としては、特に制限されず、例えば、慣用のコーター（ナイフコーター、リバースコータ、ロールコータ等）を用いて塗布する方法が挙げられる。塗布厚みは、所定の発泡構造を形成する点から、例えば、０．３乃至２．５mm、好ましくは０．５乃至２．０mm、更に好ましくは０．８乃至１．５mmである。
(2) Polyurethane resin solution coating process The substrate used in the polyurethane resin solution coating process may be a flexible material, such as a plastic film (polyester film, polyolefin film, etc.), a nonwoven fabric, or the like. . The method of applying the polyurethane resin-containing solution to the substrate is not particularly limited, and examples thereof include a method of applying using a conventional coater (knife coater, reverse coater, roll coater, etc.). The coating thickness is, for example, 0.3 to 2.5 mm, preferably 0.5 to 2.0 mm, and more preferably 0.8 to 1.5 mm from the viewpoint of forming a predetermined foam structure.
(3)ポリウレタン樹脂の凝固再生工程
ポリウレタン樹脂の凝固再生工程で、ポリウレタン樹脂溶液が塗布された基材を浸漬する凝固液は、ポリウレタン樹脂に対する貧溶媒（水等）を主成分とする。凝固液としては、例えば、水のみでも良いが、水と極性の溶剤（例えば、ＤＭＦ、ＤＭＡｃ、ＴＨＦ、ＤＭＳＯ、ＮＭＰ、アセトン等）との混合溶液等としても良い。尚、混合溶液中の極性の溶剤の濃度としては、０．１乃至３０質量％が好ましい。
(3) Polyurethane resin coagulation regeneration step In the polyurethane resin coagulation regeneration step, the coagulation liquid for immersing the base material coated with the polyurethane resin solution contains a poor solvent (such as water) for the polyurethane resin as a main component. As the coagulation liquid, for example, water alone may be used, or a mixed solution of water and a polar solvent (for example, DMF, DMAc, THF, DMSO, NMP, acetone, etc.) may be used. The concentration of the polar solvent in the mixed solution is preferably 0.1 to 30% by mass.
ポリウレタン樹脂の凝固再生工程により、基材上で凝固したポリウレタン発泡シートが得られる。本発明の研磨パッドの製造方法は、更に、基材上で凝固して得られたポリウレタン発泡シートを、必要により基材から剥離した後、洗浄及び乾燥する工程を含んでいても良い。 A polyurethane foam sheet solidified on the substrate can be obtained by the solidification regeneration process of the polyurethane resin. The manufacturing method of the polishing pad of the present invention may further include a step of washing and drying the polyurethane foam sheet obtained by coagulation on the substrate, if necessary, after peeling from the substrate.
(4)ポリウレタン樹脂の洗浄及び乾燥工程
洗浄及び乾燥により、ポリウレタン樹脂中に残留する溶剤（ＤＭＦ）及び凝固液（水）が除去される。洗浄に用いられる洗浄液は、通常、水が使用される。乾燥は、例えば、８０乃至１５０℃で５乃至６０分程度行う。
(4) Washing and drying process of polyurethane resin By washing and drying, the solvent (DMF) and coagulating liquid (water) remaining in the polyurethane resin are removed. Water is usually used as the cleaning liquid used for cleaning. Drying is performed at 80 to 150 ° C. for about 5 to 60 minutes, for example.
本発明の研磨パッドの製造方法は、更に、表面又は裏面又は表面及び裏面に研削処理を施したり、必要により切削による溝加工やエンボス加工等の表面処理を施しても良い。 In the method for producing a polishing pad of the present invention, the front surface or the back surface or the front surface and the back surface may be subjected to a grinding treatment, or a surface treatment such as a groove processing or embossing by cutting may be performed as necessary.
研削処理（バフ処理）の方法は、特に制限されず、例えば、サンドペーパーによる方法が挙げられる。研削処理（バフ処理）する面は、研磨面（表面層側の面）と非研磨面（定盤貼付け側の面）のいずれか一方のみでも両者でも良い。研削処理量（バフ処理量）は、所望の表面形状に応じて、例えば、０．０５乃至０．３mm、好ましくは０．１乃至０．２mmである。これにより、研磨パッドの研磨面に、開口が形成されるとともに、シートの厚みが均一化される。 The method for grinding (buffing) is not particularly limited, and examples thereof include a sandpaper method. The surface to be ground (buffed) may be either a polished surface (surface on the surface layer side) or a non-polished surface (surface on the surface plate attaching side) or both. The grinding processing amount (buff processing amount) is, for example, 0.05 to 0.3 mm, preferably 0.1 to 0.2 mm, depending on the desired surface shape. Thereby, an opening is formed in the polishing surface of the polishing pad, and the thickness of the sheet is made uniform.
溝加工やエンボス加工により形成された凹部は、ランダムに形成しても良いが、規則的（例えば、格子状、同心円状、放射状、ハニカム状）に形成しても良い。凹部の幅は、例えば、０．３乃至３．０mm、好ましくは０．５乃至１．５mm、更に好ましくは０．８乃至１．２mmである。隣り合う凹部の平均中心間距離は、例えば、１乃至１００mm、好ましくは２乃至２０mmである。これにより、研磨パッドの表面層側へのスラリーの供給と排出を促すことができる。 The concave portions formed by grooving or embossing may be formed randomly, but may be formed regularly (for example, in a lattice shape, a concentric circle shape, a radial shape, or a honeycomb shape). The width of the recess is, for example, 0.3 to 3.0 mm, preferably 0.5 to 1.5 mm, and more preferably 0.8 to 1.2 mm. The average center distance between adjacent concave portions is, for example, 1 to 100 mm, preferably 2 to 20 mm. Thereby, supply and discharge of the slurry to the surface layer side of the polishing pad can be promoted.
４．研磨パッドの発泡構造
本発明による研磨パッドの製造に適用される湿式成膜法は、前述の通り、成膜するポリウレタン樹脂を有機溶媒に溶解させ、その樹脂溶液をシート状の基材に塗布後、該有機溶媒は溶解するが該樹脂は溶解しない凝固液中に浸漬して該有機溶媒を置換し、凝固させ、洗浄し、乾燥して発泡層を形成する。通常、湿式成膜法によりポリウレタン発泡シートを製造すると、上記発泡層は多孔質構造に形成されるが、そのメカニズムは前記ポリウレタン樹脂が凝固液中を通って凝固する際、ポリウレタン樹脂中の溶媒が凝固液中に抜け凝固液が樹脂層内に入り置換凝固するときに、ポリウレタン樹脂中に形成される空洞部が研磨シートの発泡となる。この際、略涙形状のマクロ発泡（以下、涙形発泡という）とともに、この涙形発泡よりも小さな微細発泡が連通してポリウレタン発泡シートの全体に形成される。
4). Foam structure of polishing pad As described above, the wet film-forming method applied to the production of the polishing pad according to the present invention involves dissolving the polyurethane resin to be formed in an organic solvent and applying the resin solution to a sheet-like substrate. The organic solvent is dissolved but the resin is not dissolved, soaking in a coagulating liquid to replace the organic solvent, coagulating, washing, and drying to form a foamed layer. Normally, when a polyurethane foam sheet is produced by a wet film forming method, the foam layer is formed into a porous structure. The mechanism is that when the polyurethane resin solidifies through the coagulating liquid, the solvent in the polyurethane resin is When the coagulated liquid that falls into the coagulated liquid enters the resin layer and undergoes substitutional solidification, the cavity formed in the polyurethane resin becomes the foam of the abrasive sheet. At this time, macro foam having a substantially tear shape (hereinafter referred to as tear foam) and fine foam smaller than the tear foam are communicated to form the entire polyurethane foam sheet.
涙形発泡は、ポリウレタン樹脂の凝固再生工程で形成され、異方性があり、研磨パッドの研磨層表面から底部に向けて発泡径が漸次大きくなる形状を意味し、通常、研磨層の研磨面の側が先細りとなる形状を意味する。涙形発泡は、微細発泡に比べるとはるかに大きな断面積又は体積を有する。従って、涙形発泡と微細発泡とは容易に区別することができる。この涙形発泡が成長するときに、発泡が生じたところの微小繊維状セルロースが発泡の成長とともに押し動かされ、発泡の成長により肉厚が薄く構造的に弱くなった涙形発泡セル間の樹脂部分により密な状態となって分散する。より密に分散した微小繊維状セルロースによって発泡セル間の樹脂部が強化される。 Tear-shaped foam is formed by the process of coagulating and regenerating polyurethane resin and is anisotropic, meaning that the foam diameter gradually increases from the polishing layer surface to the bottom of the polishing pad. This means a shape with a tapered side. Teardrop foam has a much larger cross-sectional area or volume than microfoam. Therefore, it is easy to distinguish between tear-shaped foam and fine foam. When this tear-shaped foam grows, the microfibrous cellulose where foaming has occurred is pushed along with the growth of the foam, and the resin between the tear-shaped foamed cells is thinned and structurally weakened by the growth of foam. Disperses in a denser state. The resin part between the foamed cells is reinforced by the fine fibrous cellulose dispersed more densely.
涙形発泡が凝固再生工程で形成された後、洗浄工程を経て、乾燥工程で凝固浴の水分をポリウレタン発泡シートより除去すると、ポリウレタン樹脂中に均一かつ密に分散された微小繊維状セルロースが水素結合によりウレタン樹脂と強固なネットワークを形成し、この微小繊維状セルロースのネットワークが涙形発泡による構造上の強度不足を改善し、研磨パッドの耐久性を向上させるとともに、ポリウレタン発泡シートの剛性を上げ、研磨パッドとして使用されるときの耐摩耗性が向上しパッド使用可能時間を向上させることができる。 After the tear-shaped foam is formed in the coagulation regeneration process, after the washing process, the moisture in the coagulation bath is removed from the polyurethane foam sheet in the drying process, the fine fibrous cellulose uniformly and densely dispersed in the polyurethane resin becomes hydrogen. A strong network is formed with the urethane resin by bonding, and this microfibrous cellulose network improves the structural strength deficiency due to tear foaming, improves the durability of the polishing pad, and increases the rigidity of the polyurethane foam sheet The wear resistance when used as a polishing pad is improved, and the usable time of the pad can be improved.
微細発泡は、湿式成膜法により形成される涙形発泡よりも小さい緻密な発泡であって、ポリウレタン発泡シートを厚さ方向の任意の断面で切断したときに、５乃至４０μmの発泡の開口径（発泡径）を有する開口部を形成する発泡である。 The fine foam is a fine foam smaller than the teardrop-shaped foam formed by the wet film forming method, and when the polyurethane foam sheet is cut in an arbitrary cross section in the thickness direction, the opening diameter of the foam of 5 to 40 μm Foam forming an opening having (foam diameter).
ここで、微細発泡の発泡径とは、走査型電子顕微鏡（ＳＥＭ）により１０００倍で撮影したポリウレタン発泡シートの断面画像を二値化処理し、任意の領域に存在する発泡の円相当直径の平均値である。本発明では、涙形発泡の周囲の樹脂壁に存在する、微細発泡の円相当直径を大きくすることができ、該樹脂壁の空隙率が大きいという特徴を有する。該特徴が、研磨パッドのスラリーの馴染みを向上でき、研磨レート安定性を向上できる理由の一つと推測される。 Here, the foam diameter of the fine foam is the average of the equivalent circle diameter of the foam present in an arbitrary region by binarizing the cross-sectional image of the polyurethane foam sheet taken at 1000 times with a scanning electron microscope (SEM). Value. The present invention is characterized in that the diameter of a circle corresponding to a circle of fine foam existing in the resin wall around the teardrop-shaped foam can be increased and the porosity of the resin wall is large. This feature is presumed to be one of the reasons that the familiarity of the slurry of the polishing pad can be improved and the polishing rate stability can be improved.
尚、本明細書において、ポリウレタン発泡シートの厚さ方向とは、ポリウレタン発泡シートの被研磨物と接触する面（研磨面）と直交する方向で、該研磨面から、該研磨面とは反対側の面へと向かう方向を意味する。 In the present specification, the thickness direction of the polyurethane foam sheet is a direction orthogonal to the surface (polishing surface) of the polyurethane foam sheet in contact with the object to be polished, from the polishing surface to the opposite side of the polishing surface. It means the direction toward the surface.
５．具体的実施結果
５−１．実施例１乃至３、比較例１乃至４の研磨パッドを製造した。
5. Specific implementation results 5-1. The polishing pads of Examples 1 to 3 and Comparative Examples 1 to 4 were manufactured.
（実施例１）
ポリウレタン樹脂固形分に対し比表面積１５０m2/gの微小繊維状セルロース１質量％を分散させたＤＭＦ３０部と１００％モジュラス６．０MPaのポリエステル系ポリウレタン樹脂含有ＤＭＦ溶液（固形分濃度３０質量％）１００部を混合することによりポリウレタン樹脂溶液を得た。得られたポリウレタン樹脂溶液をポリエステルフィルム（厚さ：１８８μm）上に塗工した。樹脂溶液を成膜基材上に塗布する際に、塗布装置のクリアランスを１．４mmに設定した。その後、樹脂含有溶液をキャストしたポリエステルフィルムを凝固浴（凝固液は水）に１８℃で６０分間浸漬し、該樹脂含有溶液を凝固させた後、洗浄・乾燥させて、成膜基材上より剥離し、ポリウレタン発泡シートを得た。
Example 1
30 parts of DMF in which 1% by mass of microfibrous cellulose having a specific surface area of 150 m 2 / g is dispersed with respect to the solid content of the polyurethane resin and 100% modulus of 6.0 MPa polyester-based polyurethane resin-containing DMF solution (solid content concentration: 30% by mass) A polyurethane resin solution was obtained by mixing the parts. The obtained polyurethane resin solution was coated on a polyester film (thickness: 188 μm). When applying the resin solution on the film-forming substrate, the clearance of the coating apparatus was set to 1.4 mm. Thereafter, the polyester film casted with the resin-containing solution is immersed in a coagulation bath (coagulation liquid is water) at 18 ° C. for 60 minutes to solidify the resin-containing solution, and then washed and dried. The polyurethane foam sheet was obtained by peeling.
得られたポリウレタン発泡シートの表面に形成されたスキン層側に研削処理を施した（研削量：２００μm）。その後、ポリウレタン発泡シートの研削処理面とは反対側の面にＰＥＴ基材を接着剤を介して貼り合わせ、ポリウレタン発泡シートの研削処理面側を格子状の金型でエンボス加工後、ＰＥＴ基材と両面テープとを貼り合わせ、厚さ１．２mmの研磨パッドを得た。 The skin layer side formed on the surface of the obtained polyurethane foam sheet was ground (grinding amount: 200 μm). Thereafter, a PET base material is bonded to the surface of the polyurethane foam sheet opposite to the ground surface via an adhesive, and the embossed surface of the polyurethane foam sheet is embossed with a grid mold, And a double-sided tape were bonded together to obtain a polishing pad having a thickness of 1.2 mm.
（実施例２）
微小繊維としてキチン微小繊維（比表面積２００m2/g）を使用した以外、実施例１と同様にして研磨パッドを作製した。
(Example 2)
A polishing pad was prepared in the same manner as in Example 1 except that chitin microfibers (specific surface area 200 m 2 / g) were used as the microfibers.
（実施例３）
微小繊維の添加量を３質量％とした以外、実施例１と同様にして研磨パッドを作製した。
(Example 3)
A polishing pad was produced in the same manner as in Example 1 except that the addition amount of microfibers was 3% by mass.
（比較例１）
微小繊維を添加しない以外、実施例１と同様にして研磨パッドを作製した。
(Comparative Example 1)
A polishing pad was prepared in the same manner as in Example 1 except that no microfiber was added.
（比較例２）
微小繊維として比表面積０．４m2/gのセルロース微小繊維を使用した以外、実施例１と同様にして研磨パッドを作製した。
(Comparative Example 2)
A polishing pad was prepared in the same manner as in Example 1 except that cellulose microfiber having a specific surface area of 0.4 m 2 / g was used as the microfiber.
（比較例３）
微小繊維の代わりにカーボンブラック（比表面積２２５m2/g）を添加した以外、実施例１と同様にして研磨パッドを作製した。
(Comparative Example 3)
A polishing pad was prepared in the same manner as in Example 1 except that carbon black (specific surface area of 225 m 2 / g) was added instead of the fine fibers.
（比較例４）
１００％モジュラス６．０MPaのポリエステル系ポリウレタン樹脂含有ＤＭＦ溶液（固形分濃度３０質量％）（１００部）、ＤＭＦ（４０部）、貧溶媒である水（２部）、シリコン系ノニオン性界面活性剤（５部）、及び、２０％酢酸セルロースＤＭＦ溶液（２部）を混合することにより得た樹脂含有溶液を用いて、実施例１と同様にして研磨パッドを作製した。
(Comparative Example 4)
100% modulus 6.0 MPa polyester-based polyurethane resin-containing DMF solution (solid content concentration 30% by mass) (100 parts), DMF (40 parts), poor solvent water (2 parts), silicon-based nonionic surfactant A polishing pad was prepared in the same manner as in Example 1 using a resin-containing solution obtained by mixing (5 parts) and a 20% cellulose acetate DMF solution (2 parts).
５−２．各実施例及び比較例の研磨パッドについて、径が１０μmを越す微細発泡の有無と、研磨均一性と、スクラッチの有無を調査し、表１の結果を得た。 5-2. About the polishing pad of each Example and the comparative example, the presence or absence of the fine foam exceeding 10 micrometers in diameter, polishing uniformity, and the presence or absence of a scratch were investigated, and the result of Table 1 was obtained.
（涙形発泡の成長）
涙形発泡の様子を走査型電子顕微鏡（日本電子株式会社製、JSM-5500LV）で５０倍に拡大し５ヶ所観察した。ポリウレタン発泡シートの厚み全体にわたり成長しているものを○とし、発泡の成長にバラつきがあるものを×として評価した。結果を表１に示す。
(Growth of tear-shaped foam)
The tear-shaped foaming was magnified 50 times with a scanning electron microscope (manufactured by JEOL Ltd., JSM-5500LV) and observed at five locations. The case where the polyurethane foam sheet was grown over the entire thickness was evaluated as “◯”, and the case where the foam growth was uneven was evaluated as “X”. The results are shown in Table 1.
（直径が１０μmを越す微細発泡の有無）
微細発泡の測定は、走査型電子顕微鏡（日本電子株式会社製、JSM-5500LV）で約５mm四方の範囲を６００倍に拡大し９ヶ所観察した。この画像を画像処理ソフト（Image Analyzer V20LAB Ver.1.3、ニコン製）により二値化処理して計測領域面積３０９２９．８８３μm2の範囲における微細発泡を確認し、各々の開口部の面積から円相当直径を発泡径として算出した。ポリウレタン発泡シートを厚さ方向に切断して得られた断面９ヶ所を観察し、発泡径１乃至４０μmのうち、発泡径１０乃至４０μmの発泡の有無を確認した。結果を表１に示す。
(Presence or absence of fine foam with a diameter exceeding 10μm)
The fine foaming was measured with a scanning electron microscope (manufactured by JEOL Ltd., JSM-5500LV). This image is binarized by image processing software (Image Analyzer V20LAB Ver.1.3, manufactured by Nikon) to confirm fine foaming in the measurement area area 30929.883 μm 2 , and the equivalent circle diameter is determined from the area of each opening. Was calculated as the foam diameter. Nine cross sections obtained by cutting the polyurethane foam sheet in the thickness direction were observed, and the presence or absence of foaming having a foaming diameter of 10 to 40 μm was confirmed among the foaming diameters of 1 to 40 μm. The results are shown in Table 1.
測定の際は、ＳＥＭ画像より認識できる開口部を二値化処理で的確に捉えることができるように、コントラストを調整した。本実施例では、ＳＥＭ倍率６００倍、加速電圧２０ｋV、スポットサイズ２５、作動距離２１mmの条件でＳＥＭ画像を撮影し、二値化処理時に開口部を正しく捉えられるようにした。 At the time of measurement, the contrast was adjusted so that an opening recognizable from the SEM image can be accurately grasped by binarization processing. In this example, an SEM image was taken under conditions of an SEM magnification of 600 times, an acceleration voltage of 20 kV, a spot size of 25, and a working distance of 21 mm so that the opening could be correctly captured during binarization processing.
図１、図２は実施例１、３のシート断面のＳＥＭ写真を示し、図３、図４は比較例１、４のＳＥＭ写真を示す。尚、写真中の縦長発泡が涙形発泡であり、樹脂部分よりも濃色の黒点状に見えるものが微細発泡である。 1 and 2 show SEM photographs of sheet cross sections of Examples 1 and 3, and FIGS. 3 and 4 show SEM photographs of Comparative Examples 1 and 4, respectively. In addition, the vertically long foam in the photograph is a tear-shaped foam, and the one that looks darker than the resin part is the fine foam.
＜研磨試験＞
各実施例及び比較例の研磨パッドについて、以下の研磨条件で研磨加工を行い、研磨均一性及びスクラッチの有無を測定した。被研磨物としては、１２インチのＴＥＯＳ膜基板（均一性（ＣＶ％）が１３％）を用いた。２５枚の基板を準じ研磨し、１枚目、１０枚目、２５枚目の基板における研磨均一性を評価した。
<Polishing test>
About the polishing pad of each Example and a comparative example, it grind | polished on the following grinding | polishing conditions, and measured the uniformity of grinding | polishing and the presence or absence of a scratch. As an object to be polished, a 12-inch TEOS film substrate (uniformity (CV%) was 13%) was used. The 25 substrates were polished in accordance with the polishing uniformity of the 1st, 10th and 25th substrates.
（研磨均一性）
研磨均一性は、研磨加工前後の基板の絶縁膜について各々１７箇所の厚み測定結果のバラツキ（標準偏差÷平均値）から求めた。尚、厚み測定は、光学式膜厚膜質測定器（ＫＬＡテンコール社製、ASET-F5x）のＤＢＳモードにて測定した。
(Polishing uniformity)
Polishing uniformity was determined from the variation (standard deviation ÷ average value) of the thickness measurement results at 17 locations on the insulating film of the substrate before and after polishing. The thickness was measured in the DBS mode of an optical film thickness measuring device (manufactured by KLA Tencor, ASET-F5x).
（スクラッチの有無）
スクラッチの評価では、２５枚の基板を繰り返し３回順次研磨し、研磨加工後の２１乃至２５枚目の基板５枚について、パターンなしウェハ表面検査装置（ＫＬＡテンコール社製、Sufscan SP1DLS）の高感度測定モードにて測定し、基板表面におけるスクラッチの有無を評価した。
(Scratch)
In the scratch evaluation, 25 substrates were repeatedly and sequentially polished three times, and the high sensitivity of the pattern-less wafer surface inspection device (Sufscan SP1DLS, manufactured by KLA Tencor) was applied to the 21st to 25th substrates after polishing. Measurement was performed in measurement mode to evaluate the presence or absence of scratches on the substrate surface.
尚、上記試験で用いた研磨条件は以下の通りである。
・使用研磨機：荏原製作所社製、F-REX300
・回転数：（定盤）７０rpm、（トップリング）７１rpm
・研磨圧力：２２０hPa
・研磨剤：キャボット社製、品番：ＳＳ２５（ＳＳ２５原液：純水＝１：１の混合液を使用）
・研磨剤温度：３０℃
・研磨剤吐出量：２００ml/min
・使用ワーク（被研磨物）：１２インチφシリコンウェハ上にテトラエトキシシランをＣＶＤで絶縁膜１μmの厚さになるように形成した基板
・研磨時間：６０秒間／各回
・ドレッシング：（研磨布貼付後）１０min
The polishing conditions used in the above test are as follows.
・ Use polishing machine: F-REX300, manufactured by Ebara Corporation
・ Rotation speed: (Surface plate) 70rpm, (Top ring) 71rpm
・ Polishing pressure: 220 hPa
・ Abrasive: manufactured by Cabot, product number: SS25 (SS25 undiluted solution: pure water = 1: 1 mixture)
・ Abrasive temperature: 30 ℃
・ Abrasive discharge rate: 200ml / min
・ Work used (to be polished): Substrate formed by depositing tetraethoxysilane on a 12-inch φ silicon wafer by CVD to a thickness of 1 μm of insulation film ・ Polishing time: 60 seconds / each time After) 10min
商品価値上、以下のようにして研磨試験の結果を評価した。
研磨均一性は、７．０以下（CV％）を○、７．０超過乃至８．０以下（CV％）を△、８．０超過（CV％）を×として評価した。
In terms of commercial value, the results of the polishing test were evaluated as follows.
Polishing uniformity was evaluated by grading 7.0 or less (CV%) as ◯, exceeding 7.0 to 8.0 or less (CV%) as Δ, and exceeding 8.0 (CV%) as x.
スクラッチの有無は、無（０枚）を○、有（１枚以上）を×として評価した。 The presence / absence of scratches was evaluated as 0 (no sheet) and x (existing 1 or more).
そして、研磨レート、研磨均一性及びスクラッチの有無の結果全てが○のサンプルを好ましい例（実施例）とし、×が１つでもあるサンプルを、本発明において好ましくない例（比較例）として評価した。 Then, the samples with all the results of the polishing rate, the polishing uniformity and the presence or absence of scratches were evaluated as preferable examples (Examples), and the samples with even one x were evaluated as unfavorable examples (Comparative Examples) in the present invention. .
実施例１乃至３はスクラッチ性、研磨均一性とも良好な研磨加工を行うことができた。一方、微小繊維を添加しない比較例１では、硬質成分を含まないため、被研磨物にスクラッチを与えることはなかったが、研磨パッドの発泡が十分に成長しておらず、パッド厚み全体にわたり形成された発泡とパッド厚み半分までしか形成されない発泡がランダムに存在する不均一なものとなり、発泡が乱れたことで研磨均一性が劣るものであった。比較例２では、比表面積の低い微小繊維状セルロースであるため、繊維径が大きく、ポリウレタン樹脂中での分散性が低いものとなり、発泡の状態は微小繊維状セルロースを含まない比較例１と同様となり、研磨均一性も悪化した。更に微小繊維状セルロースが凝集成分としてスクラッチの要因となってしまったことが考えられる。比較例３のカーボンブラックを入れた研磨パッドでは、涙形発泡の成長は十分であったものの、凝集したカーボン由来のスクラッチが見られた。比較例４の酢酸セルロースを入れたパッドでは、微細発泡の拡大を確認することができたが、同時に涙形発泡が縮小してしまい、涙形発泡の成長が十分ではないため研磨均一性が悪化した。 In Examples 1 to 3, both the scratch property and the polishing uniformity could be polished well. On the other hand, in Comparative Example 1 in which no microfibers were added, since no hard component was contained, the object to be polished was not scratched, but the foaming of the polishing pad was not sufficiently grown and formed over the entire pad thickness. The foamed foam and the foam formed only up to half the pad thickness were randomly present, and the foaming was disturbed, resulting in poor polishing uniformity. In Comparative Example 2, since it is a microfibrous cellulose having a low specific surface area, the fiber diameter is large and the dispersibility in the polyurethane resin is low, and the foamed state is the same as that of Comparative Example 1 not containing the microfibrous cellulose. As a result, the polishing uniformity also deteriorated. Furthermore, it is considered that the microfibrous cellulose has become a cause of scratches as an aggregate component. In the polishing pad containing the carbon black of Comparative Example 3, although the growth of the teardrop-shaped foam was sufficient, a scratch derived from agglomerated carbon was observed. In the pad containing cellulose acetate of Comparative Example 4, the expansion of fine foam could be confirmed, but at the same time, the tear-shaped foam was reduced, and the growth of the tear-shaped foam was not sufficient, so the polishing uniformity was deteriorated. did.
本発明によれば、研磨パッドにおいて、被研磨物に対する研磨傷の発生を抑制しながら、被研磨物の表面を平坦化し得る研磨均一性の向上を図ることができる。 ADVANTAGE OF THE INVENTION According to this invention, the polishing uniformity which can planarize the surface of a to-be-polished object can be aimed at, suppressing generation | occurrence | production of the polishing flaw with respect to a to-be-polished object in a polishing pad.
Claims (3)
研磨層が、比表面積１０乃至５００m2/gの微小繊維を含む研磨パッド。 A polishing pad having, as a polishing layer, a polyurethane foam sheet having a plurality of tear-shaped foams formed by a wet film-forming method,
A polishing pad, wherein the polishing layer comprises fine fibers having a specific surface area of 10 to 500 m 2 / g.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017069360A JP6935214B2 (en) | 2017-03-30 | 2017-03-30 | Abrasive pad |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2021037478A (en) * | 2019-09-04 | 2021-03-11 | 富士紡ホールディングス株式会社 | Cleaning sheet and cleaning method using the same |
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| JP2002075934A (en) * | 2000-08-29 | 2002-03-15 | Toray Ind Inc | Pad for polishing, and apparatus and method for polishing |
| JP2005329491A (en) * | 2004-05-19 | 2005-12-02 | Nitta Haas Inc | Abrasive cloth for finishing polishing |
| JP2009203412A (en) * | 2008-02-29 | 2009-09-10 | Inoac Corp | Water-absorbing polyurethane foam |
| US20110177305A1 (en) * | 2010-01-20 | 2011-07-21 | San Fang Chemical Industry Co., Ltd. | Polishing pad and method for making the same |
| JP2011224845A (en) * | 2010-04-19 | 2011-11-10 | Teijin Cordley Ltd | Method for producing porous sheet-like object |
| JP2013194163A (en) * | 2012-03-21 | 2013-09-30 | Dic Corp | Polyurethane resin composition for polishing pads, polyurethane polishing pad and method for producing the same |
| JP2014069273A (en) * | 2012-09-28 | 2014-04-21 | Fujibo Holdings Inc | Polishing pad and method of producing the same |
| WO2014057740A1 (en) * | 2012-10-09 | 2014-04-17 | Dic株式会社 | Bump cushion |
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| JP2021037478A (en) * | 2019-09-04 | 2021-03-11 | 富士紡ホールディングス株式会社 | Cleaning sheet and cleaning method using the same |
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| JP6935214B2 (en) | 2021-09-15 |
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