JP2008284619A - Method for manufacturing polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polishing pad (polishing layer) which is superior in its flattening characteristics, and can suppress the generation of scratches, and can perform polishing at a high polishing speed. <P>SOLUTION: A reinforcing layer formed by plating copper on a non-woven fabric or a woven fabric is preliminarily arranged in a die. Then, an Sn composite containing a metallic component including irregular shape Sn powder and/or Sn alloy powder produced by the water atomization method, thermoplastic resin such as polyurethane and/or thermoplastic elastomer, and an organic solvent is poured into the die. After that, a metallic sheet is manufactured by removing the organic solvent. Then, the metallic sheet is pressed in a hot state so as to reduce the electric resistance of the polishing sheet and so as to make its surface smooth. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a polishing pad used in a step of forming a metal wiring pattern by flattening a semiconductor device having a metal film formed on a wafer (electrochemical mechanical polishing: ECMP).

  A typical material that requires high surface flatness is a single crystal silicon disk called a silicon wafer for manufacturing a semiconductor integrated circuit (IC, LSI). Silicon wafers have a highly accurate surface in each process of stacking and forming oxide films and metal films in order to form reliable semiconductor junctions of various thin films used for circuit formation in IC and LSI manufacturing processes. It is required to finish flat. In such a polishing finishing process, a polishing pad is generally fixed to a rotatable support disk called a platen, and a workpiece such as a semiconductor wafer is fixed to a polishing head. A polishing operation is performed by generating a relative speed between the platen and the polishing head by both movements, and continuously supplying a polishing slurry containing abrasive grains onto the polishing pad.

  Examples of the metal film for wiring include Al, W, and Cu. In recent years, electrochemical mechanical polishing (ECMP) has attracted attention as a method for polishing such a metal film. ECMP is a method in which a direct current is passed through an electrolytic solution between a wafer serving as an anode and a platen serving as a cathode to electrochemically dissolve and remove the metal film on the wafer surface.

  As polishing pads used in ECMP, for example, the following are proposed.

  Patent Document 1 discloses a polishing pad made of a thermoplastic or thermosetting material and having a groove formed on the polishing surface, and having a conductive layer formed in the groove. .

  Patent Document 2 discloses a conductive polishing pad in which a conductive surface layer is laminated on the surface of an insulating layer and a conductive sheet is laminated on the back surface. Examples of the material of the conductive surface layer include non-conductive sheets made of conductive fibers such as nonwoven fabrics and woven fabrics, or those obtained by impregnating them with thermosetting resins or elastomers.

  Patent Document 3 discloses a polishing pad formed of an elastic material such as urethane resin and containing conductive particles. As the conductive particles, spherical silicon coated with a metal film made of Au, Ag, Pt or the like is described.

  Patent Document 4 discloses a conductive polishing pad using a conductive resin, a resin in which a conductive material is dispersed, or a conductive fiber as a raw material. Polypyrrole and polyacetylene are described as the resin having conductivity. As for the resin in which a conductive material is dispersed, the resin includes polyurethane, nylon, polyester, natural rubber, elastomer, etc., and the conductive material includes carbon black, metal powder, metal oxide powder. And carbon nanotubes are described.

  Here, Cu has advantages such as low resistance and high electromigration resistance, and is expected as a next-generation wiring material. The Cu wiring pattern is usually formed by the damascene method, but there is a problem that when the Cu film is polished, a portion where the wiring part is over-processed occurs due to the density and size of the wiring pattern (so-called “thinning”). Was. In addition, the over-processing of the wiring part also has a problem that the central part of the wiring part is rapidly processed and a dent is formed (so-called “dishing”) mainly due to the elasticity of the polishing pad and the chemical effect of the slurry. It was.

  The thinning and dishing can be improved to some extent by making the polishing layer highly elastic. It is also effective to use a non-foamed hard polishing pad. However, when such a hard pad is used, since the Cu film is softer than the insulating film, scratches (scratches) are likely to occur on the Cu film surface.

  Further, the polishing characteristics of the polishing pad for polishing the metal film are required to be excellent in flattening characteristics, low in electrical resistance, and high in polishing rate.

  However, the conventional polishing pad cannot solve the above problems and requirements.

JP 2005-101585 A JP-A-2005-139480 JP 2002-93758 A JP 2004-111940 A

  An object of the present invention is to provide a method for producing a polishing pad (polishing layer) that has excellent planarization characteristics, can suppress the generation of scratches, and has a high polishing rate.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by a polishing pad manufacturing method described below, and have completed the present invention.

  That is, the present invention includes a step of placing a reinforcing layer obtained by copper plating on a nonwoven fabric or a woven fabric, a metal component containing tin powder and / or tin alloy powder, a thermoplastic resin and / or a thermoplastic elastomer, A polishing pad including a step of pouring a tin composition containing an organic solvent into the mold and then removing the organic solvent to produce a metal sheet, and a step of hot-pressing the metal sheet to produce an abrasive sheet The manufacturing method.

  The inventors of the present invention have prepared a metal sheet from the tin composition, and heat-pressed the metal sheet to perform heat compression molding, thereby being excellent in flattening characteristics, suppressing generation of scratches, and polishing with a high polishing rate. It was found that a pad was obtained. Specifically, since the tin composition of the present invention contains a metal component containing tin powder and / or tin alloy powder as a main component, the electrical resistance of the polishing pad can be extremely reduced. As a result, the energization amount is increased, and the metal film on the wafer surface is easily dissolved and removed electrochemically, so that the polishing rate is increased. Also, conventional polishing pads are non-woven fabric made of conductive fibers, or conductive materials dispersed in resin, etc. Since conductive fibers and conductive materials are in point contact with the metal film, a uniform voltage is applied to the polishing surface. It is difficult to multiply. As a result, the polishing rate became non-uniform and the planarization characteristics tended to be inferior. On the other hand, since the tin composition of the present invention is mainly composed of a metal component containing tin powder and / or tin alloy powder, the polishing surface of the polishing pad formed from the tin composition is in surface contact with the metal film. Can do. As a result, a uniform voltage can be applied to the polished surface, and the polishing rate can be made uniform, so that the planarization characteristics are improved. Moreover, since the tin and / or tin alloy that is the conductive material of the present invention is softer than Cu that is the material of the metal film for wiring, the generation of scratches can be effectively suppressed. In addition, since tin and / or tin alloy has a low melting point, it is easy to process and a flexible polishing pad can be produced.

  Moreover, in the manufacturing method of this invention, it is necessary to install beforehand the reinforcement layer which gave the copper plating to the nonwoven fabric or the woven fabric in the type | mold into which a tin composition is poured. By using the reinforcing layer, the strength and flexibility of the resulting abrasive sheet can be improved and the brittleness can be improved. As the reinforcing layer, a metal mesh, a nonwoven fabric, a woven fabric, or the like is also conceivable. However, when a metal mesh is used, it is easy to cause scratches on the polished surface when forming a concavo-convex structure for holding and renewing the electrolytic solution on the polished surface of the polishing layer, thereby easily generating scratches. Therefore, it is not preferable. When a non-woven fabric or a woven fabric is used, the adhesiveness with the metal component is lowered, and the abrasive sheet becomes brittle or easily peels inside the sheet, which is not preferable.

  Moreover, in the manufacturing method of this invention, the electrical resistance of a polishing sheet can be reduced significantly by hot-pressing a metal sheet and carrying out heat compression molding. The reason why the electrical resistance of the abrasive sheet is remarkably lowered by heat compression molding is that the tin powder and tin alloy powder are softened or melted by heating and further compressed, so that the tin and tin alloy are intimately welded to each other. It is thought that it was because.

  The tin powder and tin alloy powder are preferably irregularly shaped powders obtained by a water atomization method. By using an irregularly shaped tin powder or tin alloy powder obtained by the water atomizing method, the electrical resistance of the polishing pad can be significantly reduced as compared with a spherical one obtained by the gas atomizing method.

  The metal component preferably contains 80% by weight or more of tin powder and / or tin alloy powder. When the content of tin powder and / or tin alloy powder in the metal component is less than 80% by weight, it becomes difficult to apply a uniform voltage to the polished surface or to reduce the electrical resistance. Or other metals tend to generate scratches, or the flexibility is lost and workability tends to deteriorate.

  The thermoplastic resin is preferably a thermoplastic polyurethane resin. The thermoplastic elastomer is preferably a polyurethane-based thermoplastic elastomer. Thermoplastic resins and thermoplastic elastomers are essential components for imparting flexibility to the polishing pad, but thermoplastic polyurethane resins and polyurethane-based thermoplastic elastomers are particularly excellent in flexibility, strength, and wear resistance. Preferred material.

  The compounding weight ratio of the metal component to the thermoplastic resin and / or the thermoplastic elastomer is preferably 85:15 to 99: 1 (the former: the latter). When the compounding ratio of the metal component is less than 85% by weight, it tends to be difficult to uniformly apply a voltage to the polished surface or to reduce the electrical resistance. On the other hand, when the compounding ratio of the metal component exceeds 99% by weight, flexibility tends to be lost, workability is deteriorated, and the polishing pad tends to be brittle.

  In the production method of the present invention, an organic solvent is added to the tin composition. By adding the organic solvent, the mixing property of the tin composition is improved, and the tin composition can be made into a paste having a low viscosity. Therefore, it becomes easy to produce an abrasive sheet by molding.

  The addition amount of the organic solvent is preferably 5 to 30% by weight in the tin composition. When the organic solvent is less than 5% by weight, it becomes difficult to make the tin composition into a paste having a low viscosity, so that the uniformity of the tin composition is deteriorated or workability is deteriorated when molding. Tend to be. On the other hand, when it exceeds 30% by weight, the viscosity of the tin composition tends to be too low and workability tends to deteriorate.

  Moreover, this invention relates to the manufacturing method of the semiconductor device including the process of grind | polishing the metal film of the semiconductor wafer surface using the polishing pad manufactured by the said method.

  The tin composition of the present invention contains a metal component containing at least tin powder and / or tin alloy powder, and a thermoplastic resin and / or thermoplastic elastomer.

  As the tin powder and the tin alloy powder, a general powder obtained by a water atomizing method or a gas atomizing method can be used without particular limitation. The powder obtained by the water atomization method has an irregular shape, and the size is usually several microns to several hundred microns. On the other hand, the powder obtained by the gas atomization method is spherical, and the size is usually several microns to several hundred microns. In the present invention, it is preferable to use an irregularly shaped tin powder or tin alloy powder obtained by a water atomization method.

  Examples of the tin alloy include a tin-copper alloy, a tin-silver alloy, a tin-nickel alloy, a tin-aluminum alloy, a tin-bismuth alloy, a tin-lead alloy, and a tin-zinc alloy. Tin in the alloy is preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably 95% by weight or more.

  The metal component preferably contains 80% by weight or more of tin powder and / or tin alloy powder, more preferably 90% by weight or more, particularly preferably 95% by weight or more, and most preferably 100% by weight. is there. Examples of metal components other than those described above include, but are not limited to, copper, silver, gold, platinum, iron, aluminum, nickel, palladium, bismuth, lead, and zinc.

  Examples of the thermoplastic resin include polyurethane resin, polyester resin, polyamide resin, cellulose resin, acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, and olefin. Based resins (polyethylene, polypropylene, etc.). These resins may be used alone or in combination of two or more. Of these, it is particularly preferable to use a thermoplastic polyurethane resin.

  Examples of the thermoplastic elastomer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), and styrene-ethylene-propylene- Polystyrene thermoplastic elastomers such as styrene block copolymers (SEPS); polyolefin thermoplastic elastomers such as blended, implantable and dynamic vulcanized; syndiotactic 1,2-polybutadiene, trans 1,4-poly Examples include polydiene thermoplastic elastomers such as isoprene and natural rubber; engineering plastics thermoplastic elastomers such as polyurethane, polyester, polyamide, and fluorine. It is. These elastomers may be used alone or in combination of two or more. Of these, it is particularly preferable to use a polyurethane-based thermoplastic elastomer.

  The compounding weight ratio of the metal component to the thermoplastic resin and / or the thermoplastic elastomer is preferably 85:15 to 99: 1 (the former: the latter), and more preferably 90:10 to 97: 3.

  When manufacturing a polishing pad by a molding method, an organic solvent is added to the tin composition. The organic solvent is not particularly limited as long as it can dissolve the thermoplastic resin and the thermoplastic elastomer. For example, polar organic solvents such as dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; aromatic carbonization such as toluene and xylene Hydrogen-based solvent; aliphatic carboxylic acid ester-based solvent such as ethyl acetate and butyl acetate; ketone-based solvent such as methyl ethyl ketone, methyl isobutyl ketone and ethyl butyl ketone; normal heptane, cyclohexane, methylcyclohexane, 2-methylheptane, 3- Aliphatic hydrocarbon solvents such as methylheptane, 4-methylheptane, 2,2,5-trimethylhexane, normal octane, cyclooctane, nonane, and cyclononane. These organic solvents may be used alone or in combination of two or more. Of these, dimethylformamide is particularly preferred.

  The organic solvent is preferably blended in the tin composition in an amount of 5 to 30% by weight, more preferably 10 to 30% by weight.

  Tin composition includes conductive fillers such as carbon black and carbon nanotubes, conductive polymers such as polypyrrole, polythiophene, polyaniline and polyacetylene, metal oxide fine particles such as zinc oxide, tin oxide and indium oxide, and polymer fine particles coated with metal. In addition, a conductive material such as copper or silver fine particles coated with a noble metal, metal fibers, or carbon fibers may be included within a range that does not impair the effects of the present invention.

  Hereinafter, the manufacturing method of the polishing pad (polishing layer) using a tin composition is demonstrated. The polishing pad of the present invention may be only the polishing layer, and is a laminate of the polishing layer and other layers (for example, an adhesive layer, a cathode (copper mesh), a cushion layer, an insulating layer, a conductive layer, etc.). There may be. The polishing layer can be produced, for example, by the following method.

  A thermoplastic resin and / or thermoplastic elastomer is dissolved in an organic solvent in a heated state to prepare a polymer solution, tin powder and / or tin alloy powder is added to the polymer solution, mixed, defoamed, and a tin composition ( Tin paste) is prepared. In the mold into which the tin composition is poured, a reinforcing layer in which a non-woven fabric or a woven fabric is plated with copper is previously installed. A tin composition is poured into the mold to form a sheet, and then heated to remove the organic solvent to produce a metal sheet (thickness: 1 to 3 mm). The obtained metal sheet is hot pressed to produce an abrasive sheet.

  The reinforcing layer is produced by copper plating on a nonwoven fabric or a woven fabric. Examples of the material for the nonwoven fabric and the woven fabric include PET, PEN, PE, PP, nylon, acrylic fiber, glass fiber, and carbon fiber. Among these, it is preferable to use PET from the viewpoint of strength and flexibility. The thickness of the nonwoven fabric or woven fabric is not particularly limited, but is about 10 to 200 μm in consideration of strength and flexibility. Examples of the method for copper plating on the nonwoven fabric or the woven fabric include a chemical plating (electroless plating) method and a vacuum deposition plating method. The film thickness of the copper plating is not particularly limited, but is about 1 to 10 μm considering strength and flexibility.

  Examples of the method of hot pressing the metal sheet include a method of pressing with a hot plate and a method of pressing with a hot roll.

  The temperature when pressing with a hot plate is preferably 200 to 230 ° C., the pressure is 5 to 30 MPa, the sheet compression ratio is 40 to 70%, and the pressing time is preferably 1 to 5 minutes. More preferably, the temperature is 200 to 220 ° C., the pressure is 15 to 25 MPa, the sheet compression rate is 40 to 60%, and the pressing time is 1 to 2 minutes. By adjusting the temperature, pressure, sheet compression rate, and press time range, it is possible to optimize all of the strength, flexibility, and electrical resistance of the abrasive sheet. In addition, it is preferable that the surface of the hot plate is subjected to easy peeling treatment such as fluorine coating.

  Moreover, it is preferable to use a hot roll because the surface smoothness of the polishing sheet is improved and the generation of scratches can be further suppressed as compared with the case where pressing is performed using a hot plate. The temperature at the time of pressing with a hot roll is preferably 200 to 230 ° C., the linear pressure is 10 to 100 N / mm, and the sheet compression ratio is preferably 40 to 60%. The temperature is more preferably 205 to 225 ° C, particularly preferably 210 to 220 ° C. The linear pressure is more preferably 40 to 60 N / mm. The sheet compression rate is more preferably 45 to 55%. By adjusting the temperature, pressure, and sheet compression ratio, the strength, flexibility, and electrical resistance of the polishing sheet can all be optimized. The line speed of the metal sheet during hot roll pressing is not particularly limited, but is preferably 0.5 to 1.5 m / min. In addition, it is preferable that the surface of the heat roll is subjected to easy peeling treatment such as fluorine coating.

By hot pressing the metal sheet as described above, the electrical resistance of the obtained abrasive sheet can be significantly reduced. High electrical resistance is not preferable because heat is generated during electropolishing. The electrical resistance of the metal sheet before hot pressing is about 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ Ω, but 1.0 × 10 ^{0 to} 1.0 × 10 ⁻² Ω by hot pressing. The electrical resistance can be lowered to the extent of about 1.0 × 10 ^{−1 to} 1.0 × 10 ⁻² Ω.

  The polishing layer is manufactured through a step of cutting the polishing sheet, a step of forming a concavo-convex structure for holding and updating the electrolytic solution (slurry) on the polishing surface, and the like. The polishing layer may have a long shape of about several meters or a circular shape of about 7 to 90 cm. The thickness of the polishing layer is usually about 0.1 to 5 mm.

  The concavo-convex structure is not particularly limited as long as it holds and renews the electrolyte solution. For example, XY lattice grooves, concentric circular grooves, through holes, non-through holes, polygonal columns, cylinders, spiral grooves , Eccentric circular grooves, radial grooves, and combinations of these grooves. In addition, these concavo-convex structures are generally regular, but in order to make electrolyte retention and renewability desirable, the groove pitch, groove width, groove depth, etc. are changed for each range. It is also possible. When a polishing pad is manufactured by laminating a polishing layer, a cathode (copper mesh), and an insulating layer (cushion layer) using an adhesive layer, an electrolytic solution is provided between the polishing layer as the anode and the cathode. It is preferable to provide a through hole in the polishing layer and the adhesive layer in order to pass a direct current through the electrode.

  The total area of the grooves and through holes is preferably 10 to 80% of the polishing layer surface. If it is less than 10%, the electrolytic solution is not sufficiently supplied, so that the polishing rate is lowered, and if it exceeds 80%, the mechanical strength of the polishing layer tends to be lowered. In the case of a circular through hole, the diameter is preferably about 0.5 to 10 mm.

  The formation method of the concavo-convex structure is not particularly limited, but, for example, a method of mechanical cutting using a jig such as a tool of a predetermined size, a punching method, a press having a predetermined surface shape during hot pressing Examples thereof include a method of pressing a metal sheet with a plate and a laser processing method.

  The thickness variation of the polishing layer is preferably 100 μm or less. When the thickness variation exceeds 100 μm, the polishing layer has a large undulation, and there are portions where the contact state with the metal film is different, which adversely affects the polishing characteristics. In order to eliminate the thickness variation of the polishing layer, in general, the surface of the polishing layer is dressed with a dresser in which diamond abrasive grains are electrodeposited and fused in the initial stage of polishing. As a result, the dressing time becomes longer and the production efficiency is lowered.

  Examples of a method for suppressing the variation in the thickness of the polishing layer include a method of buffing the surface of the metal sheet. Moreover, when buffing, it is preferable to carry out stepwise with abrasives having different particle sizes.

  As shown in FIG. 1, the polishing pad 1 of the present invention may be one in which the polishing layer 2, the cathode (copper mesh) 3, and the insulating layer (cushion layer) 4 are bonded together.

  The insulating layer (cushion layer) supplements the characteristics of the polishing layer. The insulating layer is necessary in order to achieve both planarity and uniformity in a trade-off relationship in ECMP. The planarity is improved by the characteristics of the polishing layer, and the uniformity is improved by the characteristics of the insulating layer. In the polishing pad of the present invention, the insulating layer is preferably softer than the polishing layer.

  Examples of the insulating layer include polyester nonwoven fabric, nylon nonwoven fabric, fiber nonwoven fabric such as acrylic nonwoven fabric, resin-impregnated nonwoven fabric such as polyester nonwoven fabric impregnated with polyurethane, polymer foam such as polyurethane foam and polyethylene foam, butadiene rubber, Examples thereof include rubber resins such as isoprene rubber and photosensitive resins.

  As a means for bonding the polishing layer, the cathode, and the insulating layer, for example, a method of sandwiching and pressing between the double-sided tape (adhesive layer) 5 can be mentioned.

  Moreover, the polishing pad of this invention may be provided with the double-sided tape in the surface adhere | attached with a platen.

  FIG. 2 is a schematic configuration diagram showing an example of a polishing apparatus used in ECMP. In ECMP, the polishing pad 1 is generally fixed to a rotatable polishing surface plate 6 called a platen, and a material to be polished 7 such as a semiconductor wafer is fixed to a support base (polishing head) 8. Then, a relative speed is generated between the polishing surface plate 6 and the support base 8 by both movements, and further, while applying a voltage between the polishing layer 2 and the cathode 3 from the voltage application unit 9, the electrolytic solution 10 is applied. Is continuously supplied onto the polishing pad 1 to perform the polishing operation.

  As a result, the protruding portion of the metal film on the surface of the semiconductor wafer is electrochemically dissolved and removed and polished flat. Thereafter, a semiconductor device is manufactured by dicing, bonding, packaging, or the like. The semiconductor device is used for an arithmetic processing device, a memory, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Measurement and evaluation methods]
(Specific gravity measurement)
This was performed according to JIS Z8807-1976. A sample obtained by cutting the produced polishing layer into a 4 cm × 8.5 cm strip (thickness: arbitrary) was used as a specific gravity measurement sample and allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. . The specific gravity was measured using a hydrometer (manufactured by Sartorius).

(Hardness measurement)
This was performed in accordance with JIS K6253-1997. A sample obtained by cutting the prepared polishing layer into a size of 2 cm × 2 cm (thickness: arbitrary) was used as a sample for hardness measurement, and was allowed to stand for 16 hours in an environment of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%. At the time of measurement, the samples were overlapped to a thickness of 6 mm or more. The hardness was measured using a hardness meter (manufactured by Kobunshi Keiki Co., Ltd., Asker D type hardness meter).

(Evaluation of polishing characteristics)
SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used as a polishing apparatus, and polishing characteristics were evaluated using the prepared polishing pad.
The planarization characteristics are evaluated by depositing a Cu film on an 8-inch silicon wafer by 0.5 μm, and then patterning with L / S (line and space) = 25 μm / 5 μm and L / S = 5 μm / 25 μm. Then, a Cu film with a thickness of 1 μm was further deposited to produce a patterned Cu wafer with an initial step of 0.5 μm. This Cu wafer was subjected to electrolytic polishing under the following conditions, and evaluated by measuring the amount of scraping of the bottom portion of the 25 μm space when the global level difference was 2000 mm or less. The flattening characteristic is more excellent as the scraping value is smaller. The flattening characteristic ◯ is the case when the scraping amount is 500 mm or less, and the flattening characteristic × is the case when it exceeds 500 mm. An interference type film thickness measuring device (manufactured by Otsuka Electronics Co., Ltd.) was used for measuring the film thickness of the Cu film. As polishing conditions, an electrolytic solution (manufactured by AMAT, EP 3.1) was added at a flow rate of 200 ml / min during polishing, and the polishing load was 0.5 to 1 psi, the polishing platen rotating speed was 21 rpm, and the wafer rotating speed was 20 rpm.

(Scratch evaluation)
After polishing the Cu wafer under the above conditions, the scratch depth on the Cu wafer was measured using a wafer surface inspection device (P-15) manufactured by KLA-Tencor and evaluated according to the following criteria.
○: Less than 100 mm Δ: 100 mm or more and less than 150 mm ×: 150 mm or more

Example 1
In a container, 120 parts by weight of a thermoplastic polyurethane resin (manufactured by Dainichi Seisakusho, Resamine P-6165) and 480 parts by weight of dimethylformamide were placed, heated to 70 ° C. to dissolve the thermoplastic polyurethane resin, and a polyurethane resin solution was obtained. . 2880 parts by weight of tin powder (Mitsui Metal Mining, W-Sn, water atomized tin powder, irregular shape) was added to the polyurethane resin solution whose temperature was adjusted to 70 ° C., and the mixture was stirred until a uniform metal paste was obtained. The mixing ratio of the tin powder and the thermoplastic polyurethane resin is 96: 4. Then, the air contained in the metal paste was removed by decompressing the inside of the container. Reinforcing layer (made by Seiren, Su-10-33, nonwoven fabric thickness: 62 μm, copper film thickness: 5 μm) casted on a PET nonwoven fabric with copper plating (length: 85 cm, width: 85 cm, height: 2 mm), and then the metal paste was poured into the casting mold. Thereafter, the mold was placed in a dryer at 100 ° C. and dried for 16 hours to remove the solvent to obtain a metal sheet (thickness: 1.3 mm, electric resistance: 1.54 × 10 ⁶ Ω). The electrical resistance was measured with DIGITAL MULTITIMER (manufactured by YOKOGAWA, 7552).

Thereafter, the metal sheet was hot-roll pressed (temperature: 215 ° C., linear pressure: 50 N / mm, sheet compression ratio: 50%, line speed: 1 m / min), and polished layer (thickness: 0.71 mm, specific gravity: 4.5, D hardness: 55 degrees, electric resistance: 2.90 × 10 ⁻² Ω). Using a laminator, a mylar film (Sekisui Chemical Co., Ltd., 75 μm) having an adhesive layer on both sides was bonded to the polishing layer to obtain a laminated sheet. And the through-hole (diameter: 5 mm) was formed 30% of the grinding | polishing surface using the hole processing machine. Thereafter, the laminated sheet was punched out with a diameter of 78 cm.

  Thereafter, Cu mesh (made of mesh, thickness: 0.14 mm) as a cathode was bonded to the mylar film side of the laminated sheet using a laminator. And using the laminating machine, the mylar film (Sekisui Chemical Co., Ltd. make, 75 micrometers) which has an adhesive bond layer on both surfaces was bonded together to Cu mesh. Then, an insulating layer (Rogers Corporation, PORON, thickness: 4 mm) was bonded to the Mylar film using a laminator. Furthermore, using a laminating machine, a mylar film having an adhesive layer on both sides (manufactured by Sekisui Chemical Co., Ltd., 75 μm) was bonded to the insulating layer to prepare a polishing pad. The planarization characteristics of the polishing pad were good, and the scratch evaluation was good.

Example 2
In a container, 120 parts by weight of a thermoplastic polyurethane resin (manufactured by Dainichi Seisakusho, Resamine P-6165) and 480 parts by weight of dimethylformamide were placed, heated to 70 ° C. to dissolve the thermoplastic polyurethane resin, and a polyurethane resin solution was obtained. . 2880 parts by weight of tin powder (G-Sn, gas atomized tin powder, spherical shape, manufactured by Mitsui Kinzoku Mining Co., Ltd.) was added to the polyurethane resin solution whose temperature was adjusted to 70 ° C. and stirred until a uniform metal paste was obtained. The mixing ratio of the tin powder and the thermoplastic polyurethane resin is 96: 4. Then, the air contained in the metal paste was removed by decompressing the inside of the container. Reinforcing layer (made by Seiren, Su-10-33, nonwoven fabric thickness: 62 μm, copper film thickness: 5 μm) casted on a PET nonwoven fabric with copper plating (length: 85 cm, width: 85 cm, height: 2 mm), and then the metal paste was poured into the casting mold. Thereafter, the mold was placed in a dryer at 100 ° C. and dried for 16 hours to remove the solvent to obtain a metal sheet (thickness: 1.12 mm, electrical resistance: not measurable).

Thereafter, the metal sheet was hot-roll pressed (temperature: 215 ° C., linear pressure: 50 N / mm, sheet compression ratio: 50%, line speed: 1 m / min), and polished layer (thickness: 0.71 mm, specific gravity: 4.5, D hardness: 55 degrees, electric resistance: 3.60 × 10 ⁰ Ω). Thereafter, a polishing pad was produced in the same manner as in Example 1. The planarization characteristics of the polishing pad were good, and the scratch evaluation was good.

Comparative Example 1
A 500 cc container was charged with 190 g of DMF, 10 g of KB (manufactured by LION, Ketjen Black), and 350 g of 2 mmφ balls, and mixed in a ball mill at 400 rpm for 20 minutes. To the obtained primary mixed solution, 116.6 g of a DMF solution containing 20% by weight of a thermoplastic polyurethane resin was added, and further mixed with a ball mill at 400 rpm for 20 minutes. The obtained secondary mixed solution was transferred to a stainless steel vat, and DMF was removed in a vacuum dryer at 100 ° C. The obtained sheet was hot-plate pressed (temperature: 190 ° C., pressure: 10 MPa) for 1 minute to polish the layer (thickness: 1.95 mm, specific gravity: 1.3, D hardness: 19 degrees, electrical resistance: 1.50). × 10 ² Ω). Thereafter, a polishing pad was produced in the same manner as in Example 1. The planarization characteristic of the polishing pad was x, and the scratch evaluation was x.

Comparative Example 2
A polishing layer was produced in the same manner as in Example 1 except that a PET nonwoven fabric (made of Seiren, thickness: 55 μm) was used as the reinforcing layer. However, the adhesion between the metal component and the nonwoven fabric was poor, and peeling occurred inside the layer.

  From the above results, it can be seen that the polishing pad of the present invention is excellent in flattening characteristics and the effect of suppressing scratches. In addition, the polishing pad of the present invention is characterized in that the electrical resistance is extremely small and the metal film on the wafer surface is easily dissolved and removed electrochemically, so that the polishing rate is high.

Schematic sectional view showing an example of the polishing pad of the present invention Schematic configuration diagram showing an example of a polishing apparatus used in ECMP

Explanation of symbols

1: Polishing pad 2: Polishing layer 3: Cathode (copper mesh)
4: Insulating layer (cushion layer)
5: Double-sided tape (adhesive layer)
6: Polishing surface plate 7: Material to be polished (semiconductor wafer)
8: Support base (polishing head)
9: Voltage application unit 10: Electrolytic solution

Claims (7)

A step of installing a reinforcing layer in which a copper plating is applied to a nonwoven fabric or a woven fabric, a metal component containing tin powder and / or tin alloy powder, a thermoplastic resin and / or a thermoplastic elastomer, and an organic solvent A method for producing a polishing pad, comprising: a step of casting a tin composition to be poured into the mold, and thereafter producing a metal sheet by removing an organic solvent; and a step of producing a polishing sheet by hot pressing the metal sheet. The method for producing a polishing pad according to claim 1, wherein the tin powder and the tin alloy powder are irregularly shaped powders obtained by a water atomization method. The method for producing a polishing pad according to claim 1 or 2, wherein the metal component contains 80% by weight or more of tin powder and / or tin alloy powder. The method for producing a polishing pad according to claim 1, wherein the thermoplastic resin is a thermoplastic polyurethane resin, and the thermoplastic elastomer is a polyurethane-based thermoplastic elastomer. The method for producing a polishing pad according to any one of claims 1 to 4, wherein a blending weight ratio of the metal component to the thermoplastic resin and / or the thermoplastic elastomer is 85:15 to 99: 1 (the former: the latter). The method for producing a polishing pad according to claim 1, wherein the addition amount of the organic solvent is 5 to 30% by weight in the tin composition. A method for producing a semiconductor device, comprising a step of polishing a metal film on the surface of a semiconductor wafer using the polishing pad produced by the method according to claim 1.

Images