JP2009241213A - Manufacturing method of polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method excellent in flattening characteristics, restraining growth of scratches, and to manufacture a polishing pad high in polishing speed easily and favorably in productivity. <P>SOLUTION: This manufacturing method of the polishing pad includes processes of: forming a large number of through-holes A on a resin layer with an adhesive layer having the adhesive layer on one surface; forming a laminated body by accumulating a tin sheet and a flexible sheet in this order on the adhesive layer of the resin layer, laminating the tin sheet along the through-holes A by pressing the laminated body and manufacturing a laminated sheet having grooves on a tin sheet surface; manufacturing a composite sheet by forming a resin region X in the grooves and on the tin sheet surface; and forming through-holes B passing through to the resin region X from the resin layer on the composite sheet. <P>COPYRIGHT: (C)2010,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 polishing pad 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.

  Patent Document 5 describes a polishing pad for electrochemical mechanical polishing, which includes a porous polymer layer having a thickness of less than 1.5 mm and overlapping a conductive substrate.

  Patent Document 6 describes a polishing apparatus including a fabric layer and a conductive layer disposed on the fabric layer. It is described that the conductive layer includes a soft metal such as gold, tin, palladium, and palladium tin alloy.

  Patent Document 7 describes a polishing pad including a three-dimensional network of unit cells that are interconnected. The polishing pad can be converted into an eCMP ("Electrochemical Mechanical Planarization") polishing pad by introducing a groove with conductive lining and incorporating a conductor such as conductive fiber, conductive network, metal grid, or metal wire. Is described. The three-dimensional network structure can also promote fluid flow for application demands in eCMP applications, maintain a consistent surface structure, and increase the fluid flow for spent electrolysis from the eCMP process. It is described that the removal of the liquid is improved and the uniformity of the eCMP process can be improved.

  Patent Document 8 describes a polishing pad in which a contact conductor containing a scaly graphite material and a synthetic resin is provided on a polishing layer.

  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 JP 2005-335062 A JP-T-2006-527483 JP 2007-260893 A International Publication No. 07/072943 Pamphlet

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polishing pad that is excellent in flattening characteristics, can suppress generation of scratches, and has a high polishing rate with high productivity.

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

  That is, the present invention includes a step of forming a large number of through holes A in a resin layer with an adhesive layer having an adhesive layer on one side, and a tin sheet and a flexible sheet are superposed in this order on the adhesive layer of the resin layer. Forming a laminated body, pressing the laminated body to laminate a tin sheet along the through-hole A, and producing a laminated sheet having a groove on the tin sheet surface, a resin region in the groove and on the tin sheet surface The present invention relates to a method for manufacturing a polishing pad including a step of forming a composite sheet by forming X and a step of forming a through hole B penetrating from a resin layer to a resin region X in the composite sheet.

  In the polishing pad manufactured by the method of the present invention, a conductive network is densely formed by a tin sheet and a large number of through-holes B holding an electrolytic solution, and this structure reduces the surface electrical resistance of the polishing pad. be able to. 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, the metal film on the wafer surface is passivated by oxidizing the surface under acidic conditions. Since the passivated oxide film is less susceptible to electrochemical reaction, a sufficient polishing rate cannot be obtained only by electrochemical dissolution and removal. The polishing pad of the present invention has a resin layer on the polishing surface, and the metal layer and the passivated oxide film on the wafer surface can be mechanically polished by the resin layer, thereby increasing the polishing rate. .

  The resin region X is provided to protect a thin and low-strength tin sheet, and is necessary for preventing the tin sheet from being broken and imparting flexibility to the polishing pad and improving the planarization characteristics. It is an important member. The resin region X is a member that also serves as an insulating layer.

  Moreover, the manufacturing method of the polishing pad of this invention is characterized by forming the through-hole B which penetrates from the resin layer to the resin area | region X in a composite sheet. The resin layer also has a role of protecting the periphery of the through hole B so that the metal powder peeled off from the tin sheet is not mixed into the electrolytic solution in the through hole B during polishing. When the metal powder is mixed into the electrolyte in the through hole B, the metal powder easily causes a scratch on the metal film on the wafer surface. However, the resin layer protects the periphery of the through hole B with the metal powder. It can be effectively prevented.

  Further, since the resin layer is softer than Cu, which is a material for the metal film for wiring, the generation of scratches can be suppressed.

  It is preferable that the hardness of the flexible sheet is lower than the hardness of the resin layer. When the hardness of the flexible sheet is higher than the hardness of the resin layer, it is difficult to be deformed into a convex shape corresponding to the through hole A when pressed, so that a tin sheet is laminated along the through hole A of the resin layer. Becomes difficult.

  Moreover, it is preferable that the thickness of the said flexible sheet is larger than the thickness of the resin layer with an adhesive layer. When the thickness of the flexible sheet is smaller than the thickness of the resin layer with an adhesive layer, the tin sheet is not sufficiently deformed into a convex shape corresponding to the through hole A when pressed. It becomes difficult to laminate along.

  The resin layer is preferably a polyurethane layer, and more preferably a polyurethane foam layer.

  The raw material of the resin region X is preferably a thermosetting polyurethane resin, a thermoplastic polyurethane resin, or a polyurethane-based thermoplastic elastomer.

  The manufacturing method of the polishing pad of the present invention includes a step of forming a large number of through holes A in a resin layer with an adhesive layer having an adhesive layer on one side, and a tin sheet and a flexible sheet on the adhesive layer of the resin layer. A laminate is formed by overlapping in this order, and the laminate is pressed to laminate a tin sheet along the through hole A to produce a laminate sheet having a groove on the surface of the tin sheet, the inside of the groove and the tin sheet Forming a composite sheet by forming a resin region X on the surface, and forming a through hole B penetrating from the resin layer to the resin region X in the composite sheet.

  The resin layer of the resin layer with an adhesive layer may be formed of a resin material that can protect a thin and low-strength tin sheet, imparts flexibility to the polishing pad, and has an insulating property. Examples of such a resin material include polyurethane, polyolefin-based elastomer, fluorine-based resin, polycarbonate, and PTFE, and it is particularly preferable to use polyurethane. Moreover, it is preferable that the resin layer has a foamed structure in order to improve planarization characteristics. Hereinafter, a case where the resin layer is a polyurethane foam layer will be described as a specific example.

  The polyurethane foam, which is a material for the polyurethane foam layer, comprises an isocyanate component, a polyol component (such as a high molecular weight polyol and a low molecular weight polyol), and a chain extender.

  As the isocyanate component, a known compound in the field of polyurethane can be used without particular limitation. As the isocyanate component, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate; ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, etc. Aliphatic diisocyanate; 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate Isocyanate, alicyclic diisocyanates such as norbornane diisocyanate. These may be used alone or in combination of two or more.

  Examples of the high molecular weight polyol include polyether polyols typified by polytetramethylene ether glycol, polyester polyols typified by polybutylene adipate, polycaprolactone polyol, and a reaction product of a polyester glycol such as polycaprolactone and alkylene carbonate. Polyester polycarbonate polyol, polyester carbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol and then reacting the resulting reaction mixture with organic dicarboxylic acid, and polycarbonate polyol obtained by transesterification reaction between polyhydroxyl compound and aryl carbonate Etc. These may be used alone or in combination of two or more.

  As the polyol component, in addition to the above-described high molecular weight polyol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1, 4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, trimethylolpropane, glycerin, 1,2,6-hexanetriol , Pentaerythritol, tetramethylolcyclohexane, methyl glucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl) cyclohexanol, and triethanolamine It can be used in combination molecular weight polyol. Moreover, low molecular weight polyamines, such as ethylenediamine, tolylenediamine, diphenylmethanediamine, and diethylenetriamine, can also be used in combination. Also, alcohol amines such as monoethanolamine, 2- (2-aminoethylamino) ethanol, and monopropanolamine can be used in combination. These low molecular weight polyols and low molecular weight polyamines may be used alone or in combination of two or more.

  When a polyurethane foam is produced by a prepolymer method, a chain extender is used for curing the prepolymer. The chain extender is an organic compound having at least two active hydrogen groups, and examples of the active hydrogen group include a hydroxyl group, a primary or secondary amino group, and a thiol group (SH). Specifically, 4,4′-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline), 3,5 -Bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2 , 6-diamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 4,4′-diamino-3,3 ′, 5,5′-tetraethyldiphenylmethane, 4, 4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetra Sopropyldiphenylmethane, 1,2-bis (2-aminophenylthio) ethane, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane, N, N′-di-sec-butyl -4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, m-xylylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, m-phenylenediamine And polyamines exemplified by p-xylylenediamine and the like, or the low molecular weight polyols and low molecular weight polyamines mentioned above. These may be used alone or in combination of two or more.

  The polyurethane foam can be produced by applying a known urethanization technique such as a melting method or a solution method, but is preferably produced by a melting method in consideration of cost, working environment and the like.

  Polyurethane foam can be produced by either the prepolymer method or the one-shot method, but an isocyanate-terminated prepolymer is synthesized in advance from an isocyanate component and a polyol component, and this is reacted with a chain extender. Is preferred because the resulting polyurethane resin has excellent physical properties.

  In the production of the polyurethane foam, a first component containing an isocyanate group-containing compound and a second component containing an active hydrogen group-containing compound are mixed and cured. In the prepolymer method, the isocyanate-terminated prepolymer becomes an isocyanate group-containing compound, and the chain extender becomes an active hydrogen group-containing compound. In the one-shot method, the isocyanate component becomes an isocyanate group-containing compound, and the chain extender and the polyol component become active hydrogen group-containing compounds.

  Examples of the method for producing the polyurethane foam include a method of adding hollow beads, a mechanical foaming method, a chemical foaming method, and the like.

  In particular, a mechanical foaming method using a silicon surfactant which is a copolymer of polyalkylsiloxane and polyether is preferable. Examples of the silicon surfactant include SH-192, L-5340 (manufactured by Toray Dow Corning Silicon) and the like as suitable compounds.

  In addition, you may add stabilizers, such as antioxidant, a lubricant, a pigment, a filler, an antistatic agent, and another additive as needed.

An example of a method for producing a micro-bubble type polyurethane foam will be described below. The manufacturing method of this polyurethane foam has the following processes.
1) Foaming process for producing a cell dispersion of isocyanate-terminated prepolymer A silicon-based surfactant is added to the isocyanate-terminated prepolymer (first component), and the mixture is stirred in the presence of a non-reactive gas to remove the non-reactive gas. Disperse as fine bubbles to obtain a cell dispersion. When the prepolymer is solid at normal temperature, it is preheated to an appropriate temperature and melted before use.
2) Curing Agent (Chain Extender) Mixing Step A chain extender (second component) is added to the above cell dispersion, mixed and stirred to obtain a foaming reaction solution.
3) Casting process The above foaming reaction liquid is poured into a mold.
4) Curing step The foaming reaction solution poured into the mold is heated to cause reaction curing.

  As the non-reactive gas used to form the fine bubbles, non-flammable gases are preferable, and specific examples include nitrogen, oxygen, carbon dioxide, rare gases such as helium and argon, and mixed gases thereof. In view of cost, it is most preferable to use air that has been dried to remove moisture.

  A known stirring device can be used without particular limitation as a stirring device for dispersing non-reactive gas in the form of fine bubbles and dispersed in the first component containing the silicon-based surfactant. Specifically, a homogenizer, a dissolver, 2 A shaft planetary mixer (planetary mixer) is exemplified. The shape of the stirring blade of the stirring device is not particularly limited, but it is preferable to use a whipper type stirring blade because fine bubbles can be obtained.

  In addition, it is also a preferable aspect to use a different stirring apparatus for the stirring which produces a cell dispersion in a foaming process, and the stirring which adds and mixes the chain extender in a mixing process. In particular, the stirring in the mixing step may not be stirring that forms bubbles, and it is preferable to use a stirring device that does not involve large bubbles. As such an agitator, a planetary mixer is suitable. There is no problem even if the same stirring device is used as the stirring device for the foaming step and the mixing step, and it is also preferable to adjust the stirring conditions such as adjusting the rotation speed of the stirring blade as necessary. .

  In the production method of polyurethane foam, heating and post-curing the foam that has reacted until the foaming reaction liquid is poured into the mold and no longer flows is effective in improving the physical properties of the foam and is extremely suitable. It is. The foam reaction solution may be poured into the mold and immediately put into a heating oven for post cure, and heat is not immediately transferred to the reaction components under such conditions, so the bubble size does not increase. . The curing reaction is preferably performed at normal pressure because the bubble shape is stable.

  In the polyurethane foam, a known catalyst that promotes polyurethane reaction such as tertiary amine may be used. The type and addition amount of the catalyst are selected in consideration of the flow time for pouring into a mold having a predetermined shape after the mixing step.

  Polyurethane foam can be produced by weighing each component, putting it in a container and stirring it, or by continuously supplying each component and non-reactive gas to the stirrer and stirring the foaming reaction. It may be a continuous production method in which a liquid is fed to produce a molded product.

  Also, put the prepolymer that is the raw material of the polyurethane foam into the reaction vessel, and then add the chain extender, and after stirring, cast it into a casting mold of a predetermined size to make the block into a bowl shape or a band saw shape In the method of slicing using the above slicer, or in the casting step described above, a thin sheet may be formed. Alternatively, a raw material resin may be dissolved and extruded from a T-die to directly obtain a sheet-like polyurethane foam.

  The average cell diameter of the polyurethane foam is preferably 30 to 80 μm, more preferably 30 to 60 μm.

  The specific gravity of the polyurethane foam is preferably 0.5 to 1.3. When the specific gravity is less than 0.5, due to insufficient strength, the tin sheet tends to break during electropolishing or the flattening characteristics tend to deteriorate. On the other hand, when it is larger than 1.3, the flattening characteristics tend to be lowered because flexibility is lost.

  Although the hardness of a polyurethane foam is not specifically limited, It is preferable that it is 65 degrees or less with an Asker D hardness meter. When the Asker D hardness is greater than 65 degrees, the flexibility is lost, so that the flattening characteristics are lowered and scratches are likely to occur.

  The thickness of the polyurethane foam layer is not particularly limited, but is usually 0.3 to 3 mm, preferably 0.5 to 2 mm from the viewpoint of flexibility and strength.

  The adhesive layer of the resin layer with an adhesive layer may be a single adhesive layer or a double-sided tape having adhesive layers on both sides of the substrate. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. Examples of the base material include polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, polyfluoroethylene, and other fluorine-containing resins, nylon, and cellulose. A release sheet may be laminated on the surface of the adhesive layer.

  Hereinafter, the manufacturing method of the polishing pad of this invention is demonstrated, referring FIG.

  A process (a) is a process of forming many through-holes A (12) in the resin layer 11 with an adhesive layer which has the adhesive bond layer 5 on one side.

  Examples of the method of forming the through hole A (12) in the resin layer 11 with the adhesive layer include a method of punching with a press using a Thomson mold or a male and female mold, a processing method using a water cutter or a laser, and the like. However, it is not limited to these.

  The surface shape of the through-hole A (12) is not particularly limited, and examples thereof include a circle, an ellipse, a rectangle, and a polygon. In order to laminate the tin sheet without any gap along the through hole A (12), the through hole A (12) is preferably circular or elliptical. In the case of a circular shape, the diameter of the through hole A (12) is about 1 to 50 mm, preferably 3 to 20 mm.

  The cross-sectional shape of the through hole A (12) is not particularly limited, and examples thereof include a square, a rectangle, and a trapezoid.

  Examples of the formation pattern of the through holes A (12) include concentric circles, radial shapes, spiral shapes, and grid shapes. In order to perform uniform electropolishing, it is preferable that the through holes A (12) are uniformly dispersed on the surface of the resin layer 11 with an adhesive layer.

  In the step (b), a tin sheet 13 and a flexible sheet 14 are superposed in this order on the adhesive layer of the resin layer 11 with the adhesive layer in which the through hole A (12) is formed, and a laminate is formed. This is a step of pressing the body and laminating the tin sheet 13 along the through-hole A (12) to produce a laminated sheet 16 having grooves 15 on the surface of the tin sheet.

  The tin sheet 13 contains tin or a tin alloy as a raw material component. 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.

  Although the thickness in particular of the tin sheet 13 is not restrict | limited, It is preferable that it is 50-1000 micrometers, More preferably, it is 100-500 micrometers. A thickness of less than 50 μm is not preferable because the tin sheet is easily broken during polishing due to insufficient strength. On the other hand, when the thickness exceeds 1000 μm, it is difficult to laminate the tin sheet without any gap along the through hole A (12), and the flexibility of the polishing pad is lowered, which is not preferable.

  When the size of one tin sheet 13 is smaller than the size of the intended polishing pad, a plurality of tin sheets may be bonded together by an appropriate method.

  The flexible sheet 14 is a member necessary for laminating the tin sheet 13 along the through hole A (12). Specifically, since the flexible sheet 14 is easily deformed into the shape of the through hole A (12) by pressing, the tin sheet 13 sandwiched between the flexible sheet 14 and the resin layer 11 with the adhesive layer is formed in the through hole. Adhesion can be performed while following A (12).

  Examples of the material of the flexible sheet 14 include rubber, a thermoplastic elastomer, and a polymer resin foam.

  Rubbers include natural rubber, silicone rubber, acrylic rubber, urethane rubber, butadiene rubber, chloroprene rubber, isoprene rubber, nitrile rubber, epichlorohydrin rubber, butyl rubber, fluorine rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, and styrene-butadiene. For example, rubber.

  As thermoplastic elastomer (TPE), natural rubber TPE, polyurethane TPE, polyester TPE, polyamide TPE, fluorine TPE, polyolefin TPE, polyvinyl chloride TPE, styrene TPE, styrene-butadiene-styrene block Copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-isoprene-styrene block copolymer (SIS).

  Examples of the polymer resin foam include polyethylene foam and polyurethane foam.

  The hardness of the flexible sheet 14 needs to be lower than the hardness of the resin layer 4, and specifically, it is preferably 80 degrees or less with an Asker C hardness meter. When the Asker C hardness is higher than 80 degrees, it is difficult to deform into a convex shape corresponding to the through hole A (12) when pressed, so the tin sheet 13 is laminated without any gap along the through hole A (12). It becomes difficult to do.

  Moreover, the thickness of the flexible sheet | seat 14 needs to be larger than the thickness of the through-hole A (12). When the thickness of the flexible sheet 14 is smaller than the thickness of the through-hole A (12), it does not sufficiently deform into a convex shape corresponding to the through-hole A (12) when pressed. It becomes difficult to laminate without gap along (12).

  Examples of the pressing means include a press plate and a roll. The pressure at the time of pressing and the pressing time are not particularly limited as long as the tin sheet 13 can be laminated without any gap along the through-hole A (12), but the pressure is about 0.5 to 20 MPa, preferably 1 to 15 MPa. The pressing time is about 0.1 to 120 seconds, preferably 1 to 30 seconds.

  By the pressing, the tin sheet 13 is laminated along the through hole A (12), and the laminated sheet 16 having the grooves 15 on the surface of the tin sheet is produced. Here, it is necessary to produce the laminated sheet so that the surface of the resin layer 4 and the surface of the tin region 17 on the back surface side (surface side that becomes the polishing surface) of the laminated sheet are as flush as possible. When the resin layer 4 is formed of an elastic material such as polyurethane foam, the resin layer 4 is easily deformed when pressed, so that the surface of the tin region 17 is not easily flush with the surface of the resin layer 4. There is a tendency for the tin region 17 to be depressed.

  The step (c) is an optional step, and when the tin region 17 is formed in a depressed state in the step (b), the surface of the tin region 17 and the surface of the resin layer 4 are processed to be in the same plane. It is a process. Examples of the processing method include the following methods.

  (1) The viscoelastic material 18 is deposited in the groove 15 and on the surface of the tin sheet 13, and then the viscoelastic material 18 is pushed into the groove by applying pressure from above the viscoelastic material 18. The method of extruding until it becomes the same plane as 4 surfaces is mentioned.

  Examples of the viscoelastic material 18 include clay, silicon-based, urethane-based, epoxy-based, SBR-based, and butyl-based sealing materials, coating materials, adhesives, and the like. Examples of the method of applying pressure include a method of pressing with a press plate, a roll or the like. After the processing, the viscoelastic material 18 may be removed, or depending on the material, it may be used as it is to form the resin region X (19).

  (2) A method of buffing the surface of the resin layer 4 until the surface of the tin region 17 and the surface of the resin layer 4 are flush with each other can be mentioned. When buffing, it is preferable to carry out stepwise with abrasives having different particle sizes.

  Step (d) is a step of forming the composite sheet 20 by forming the resin region X (19) in the groove 15 and on the surface of the tin sheet 13. Specifically, the composite sheet 20 can be produced by the following method.

  The material for forming the resin region X (19) is not particularly limited, and for example, a thermosetting resin, a photocurable resin, a thermoplastic resin, and a thermoplastic elastomer can be used. From the viewpoint of flexibility and strength, it is preferable to use a thermosetting polyurethane resin, a thermoplastic polyurethane resin, or a polyurethane-based thermoplastic elastomer.

  (A) When forming the resin region X (19) with a thermosetting polyurethane resin

  The laminated sheet 16 is installed in the mold, and a thermosetting polyurethane resin raw material is poured into the groove 15 and the tin sheet 13 of the laminated sheet 16, and then the raw material is heated and reacted and cured to obtain a resin region X (19 ).

  The mold may be an open mold or a closed mold, but it is preferable to use a closed mold in order to omit the subsequent buffing step. When the polyurethane resin raw material is poured, the discharge port may be fixed and the raw material may be poured while traversing. In order to improve the adhesion between the tin sheet 13 and the resin region X (19), the surface of the tin sheet 13 is previously subjected to blasting, plasma treatment, corona treatment, adhesive application, or primer treatment. It is preferable. These processes may be performed in combination.

  The resin region X (19) may be foamed or non-foamed. In the case of a foam, the average cell diameter is preferably 200 μm or less, more preferably 100 μm or less.

  The thickness of the resin region X (19) on the surface of the tin sheet 13 is not particularly limited, but is usually 0.01 to 10 mm, preferably 0.2 to 5 mm, from the viewpoint of flexibility and strength.

  The D hardness of the resin region X (19) formed of a thermosetting polyurethane resin is preferably 80 degrees or less.

  After forming the resin region X (19), surface treatment such as buffing may be performed to increase the thickness accuracy.

  Further, instead of the molding method, the polyurethane resin material is discharged (applied) into the groove 15 and the tin sheet 13 of the laminated sheet 16 while feeding the laminated sheet 16 onto the conveyor. A continuous production method in which the resin region X (19) is formed by heating and reaction curing, or a reaction injection molding method (RIM) may be employed.

  (B) When the resin region X (19) is formed of a thermoplastic polyurethane resin or a polyurethane-based thermoplastic elastomer

  The laminated sheet 16 is installed in the mold, and the molten thermoplastic polyurethane resin or polyurethane-based thermoplastic elastomer is poured into the groove 15 and the tin sheet 13 of the laminated sheet 16, and then the thermoplastic polyurethane resin is cured. Thus, the resin region X (19) is formed. Instead of the molding method, an injection molding method may be adopted.

  Alternatively, the laminated sheet 16 is placed in the mold, a thermoplastic polyurethane resin sheet or a polyurethane-based thermoplastic elastomer sheet is laminated on the tin sheet 13, the resin sheet is hot-pressed and melted, and then cured. Resin region X (19) is formed. Further, instead of laminating the resin sheet on the tin sheet 13, pellets may be spread.

  When the resin region X (19) is formed of a thermoplastic polyurethane resin or a polyurethane-based thermoplastic elastomer, the D hardness is preferably 80 degrees or less.

  Step (e) is a step of forming the polishing layer 2 by forming in the composite sheet 20 through holes B (21) penetrating from the resin layer 4 to the resin region X (19). FIG. 2 is a schematic view showing the surface structure of the polishing layer 2. In addition, it is preferable to provide the adhesive layer 5 (double-sided tape) on the resin region X (19) before forming the through hole B (21) in the manufacturing process. The adhesive layer 5 is provided to bond the polishing layer 2 to the cathode layer 3.

  Examples of the method for forming the through hole B (21) include a method of punching with a press using a Thomson mold or a male and female mold, a processing method using a water cutter or a laser, and the like. When a polishing pad is produced by laminating the polishing layer 2 and the cathode layer 3 using the adhesive layer 5, a direct current is passed between the polishing layer 2 as the anode and the cathode layer 3 via an electrolytic solution. In order to energize, it is necessary to provide the through hole B (21) not only in the composite sheet 20 but also in the adhesive layer 5.

  The surface shape of the through-hole B (21) is not particularly limited, and examples thereof include a circle, an ellipse, a quadrangle, and a polygon, and a circle is preferable. In the case of a circle, the diameter is about 1 to 50 mm.

  The cross-sectional shape of the through hole B (21) is not particularly limited, and examples thereof include a square, a rectangle, and a trapezoid.

  The total surface area of the through holes B (21) is preferably 5 to 80%, more preferably 10 to 60% with respect to the surface area of the polishing layer 2. When the total surface area of the through-hole B (21) is less than 5%, the electrolytic solution is not sufficiently supplied to reduce the polishing rate, and when it exceeds 80%, the mechanical strength of the polishing layer 2 decreases, The polishing rate tends to decrease.

  The total surface area of the tin region 17 is preferably 20 to 70% with respect to the surface area of the polishing layer 2. When the total surface area of the tin region 17 is less than 20%, the area of the conductive portion of the polishing layer 2 becomes small and it becomes difficult to remove the metal film on the wafer surface electrochemically, so that the polishing rate decreases, and 70% In the case of exceeding 1, the surface area of the resin layer 4 becomes small and it becomes difficult to mechanically remove the metal film on the wafer surface, so that the polishing rate tends to decrease.

  The thickness variation of the polishing layer 2 is preferably 100 μm or less. When the thickness variation exceeds 100 μm, the polishing layer has a large waviness, and a portion having a different contact state with the metal film is formed, 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. The dressing time becomes longer and the production efficiency decreases.

  Examples of a method for suppressing the thickness variation of the polishing layer 2 include a method of buffing the surface of the polishing layer. When buffing, it is preferable to carry out stepwise with abrasives having different particle sizes.

The surface electrical resistance of the polishing layer 2 is preferably 5.0 × 10 ⁻² Ω or less. A high surface electrical resistance is not preferable because heat is generated during electropolishing.

  The polishing layer 2 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 about 0.3 to 5 mm. Moreover, you may provide the embossing or electrolyte solution groove | channel 24 for renewing electrolyte solution and discharging | emitting a by-product in the grinding | polishing surface of a grinding | polishing layer.

  The polishing layer 2 preferably has at least one anode connecting protrusion 25. The length and width of the anode connecting protrusion 25 are not particularly limited, but the length is about 20 to 40 mm and the width is about 50 to 120 mm.

  As shown in FIG. 3, the polishing pad 1 of the present invention may be a laminate of the polishing layer 2, the cathode layer 3, and the cushion layer 22. The polishing layer 2 is usually provided with an anode wire. The anode wire may be separately provided after or during the formation of the polishing layer 2, or a part of the polishing layer 2 may be integrally formed as a forming material thereof.

  A known material can be used for the cathode layer 3 without any particular limitation. For example, a copper mesh, a copper foil, a nickel foil, a composite material obtained by laminating a copper foil or a nickel foil on a resin film (PET film, etc.), a composite material obtained by depositing copper or nickel on a resin film (PET film, etc.), and the like. . The material of the cathode layer 3 is appropriately selected from those that do not contaminate the metal in relation to the metal film on the wafer surface. When the metal film on the wafer surface is copper, copper is used as the material for the cathode layer 3. Moreover, it is preferable to use a copper mesh from a viewpoint of a softness | flexibility and a flexibility.

  The cushion layer 22 supplements the characteristics of the polishing pad. The cushion layer 22 is necessary to achieve both planarity and uniformity in a trade-off relationship in ECMP. The planarity is improved by the characteristics of the polishing layer 2, and the uniformity is improved by the characteristics of the cushion layer 22. In the polishing pad of the present invention, the cushion layer 22 is preferably softer than the polishing layer 2.

  Examples of the cushion layer 22 include fiber nonwoven fabrics such as polyester nonwoven fabric, nylon nonwoven fabric, and acrylic nonwoven fabric, resin-impregnated nonwoven fabrics such as polyester nonwoven fabric impregnated with polyurethane, polymer resin foams such as polyurethane foam and polyethylene foam, and butadiene rubber. , Rubber resins such as isoprene rubber, and photosensitive resins.

  Examples of means for bonding the polishing layer 2, the cathode layer 3, and the cushion layer 22 include a method of pressing between the adhesive layers 5 (double-sided tape) and a method of using a hot melt adhesive. Further, when the resin region X (19) is formed of a thermoplastic resin or a thermoplastic elastomer, the polishing layer 2 and the cathode layer 3 may be bonded together by thermal welding.

  Moreover, the polishing pad 1 of the present invention may be provided with an adhesive layer 5 (for example, a double-sided tape) on the surface that contacts the platen. When the polishing pad is fixed to the platen by the magnetic force of the magnetic platen, a magnetic layer 23 (for example, a magnetic SUS layer) may be provided on the surface in contact with the platen.

  FIG. 4 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 pad 1 and the cathode layer 33 from the voltage application unit 9, the electrolyte solution The polishing operation is performed by continuously supplying 10 onto the polishing pad 1.

  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]
(Measurement of surface electrical resistance)
One electrode (copper electrode, φ10 mm) was connected to the protrusion for anode connection of the produced polishing pad, and the other electrode (copper electrode, φ10 mm) was connected to the tin region of the polishing surface, and the surface electrical resistance value was measured. . The electric resistance value was measured with a DIGITAL MULTITIMER (manufactured by YOKOGAWA, 7552).

(Evaluation of polishing characteristics)
Using Applied Reflexion LK ECMP (Applied Materials) as a polishing apparatus, polishing characteristics were evaluated using the prepared polishing pad.
The polishing rate was calculated from the time when a 300 mm silicon wafer with a 1 μm Cu film was electropolished under the following conditions and polished to about 0.5 μm.
The planarization characteristics are evaluated by depositing a 0.5 μm Cu film on a 300 mm silicon wafer and then patterning 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 amount of scraping is smaller. The flattening characteristic ◯ is obtained when the scraping amount is 500 mm or less, and the flattening characteristic x is obtained 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 (Applied Material, E.P3.1) was added at a flow rate of 200 ml / min during polishing, a polishing load of 0.3 to 1.0 psi, a polishing platen rotation speed of 21 rpm, and a wafer rotation speed. The pressure was 20 rpm and the applied voltage was 2.0V.

(Scratch evaluation)
Using the polishing apparatus, a 1 mm thick Cu film was formed on a 300 mm silicon wafer and subjected to electrolytic polishing under the following conditions. Then, a foreign object having a size of about 0.2 μm or more was detected with a surface defect measuring device (WM 2500, manufactured by Topcon Corporation), and the number of particles detected as a line was measured as a scratch. As polishing conditions, an electrolytic solution (Applied Material, E.P3.1) was added at a flow rate of 200 ml / min during polishing, a polishing load of 0.3 to 1.0 psi, a polishing platen rotation speed of 21 rpm, and a wafer rotation speed. 20 rpm, applied voltage 2.0 V, polishing time 120 seconds.

Example 1
(Preparation of polyurethane foam layer with adhesive layer)
100 parts by weight of an isocyanate-terminated prepolymer heated to 70 ° C. (Uniroy, Adiprene L-325) and 3 parts by weight of a silicon-based surfactant (Toray Dow Corning Silicon, SH-192) were added to the container. The mixture was mixed, adjusted to 80 ° C. and degassed under reduced pressure. Thereafter, using a mixer having a whipper-type stirring blade, a bubble dispersion was prepared by vigorously stirring so as to take in bubbles into the reaction system. The agitator was changed to a planetary mixer, and 4,4′-methylenebis (o-chloroaniline) (Ihara Chemical amine, Iharacamine MT) previously melted at 120 ° C. in the bubble dispersion was NCO / NH ₂ equivalents It added so that ratio might be set to 1.1. The mixed solution was stirred for about 1 minute and then poured into a pan-shaped open mold (casting container). When the fluidity of the mixed solution disappeared, it was put in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane foam block.
The polyurethane foam block heated to about 80 ° C. was sliced using a slicer (AGW, manufactured by VGW-125), and a polyurethane foam sheet (average cell diameter: 50 μm, specific gravity: 0.86, Asker D hardness: 52 degrees). Next, the surface of the sheet was buffed using a buffing machine (Amitech Co., Ltd.) until the thickness became 1.00 mm, the thickness accuracy was adjusted, and a polyurethane foam layer (80 cm × 80 cm) was produced. And the adhesive bond layer (Sumitomo 3M company make, 467MP, thickness 50micrometer) was bonded together to the single side | surface of a polyurethane foam layer, and the polyurethane foam layer with an adhesive bond layer was produced.

(Production of laminated sheet)
A number of through-holes A (diameter 30 mm) were formed in a polyurethane foam layer with an adhesive layer at 10 mm vertical and horizontal intervals using a hole processing machine. And on the adhesive layer of the foamed layer, a tin sheet (made of Japanese foil, thickness 0.25 mm) and a flexible sheet (made by Nippon Hojo, ES30, thickness 3.0 mm, Asker A hardness 20 degrees) are arranged in this order. The laminated body was produced by superimposing. Thereafter, the laminate was pressed from above and below (pressure: 3 MPa, time: 30 seconds), the tin sheet was laminated along the through-hole A, and a laminated sheet having grooves on the surface of the tin sheet was produced. Then, clay (Nisshin Associates, Grace) is deposited in the groove and on the surface of the tin sheet, pressed from above the clay, and the clay is pushed into the groove until the tin area becomes flush with the polyurethane foam layer surface. Extruded to produce a laminated sheet. Thereafter, the clay was removed from the laminated sheet.

(Production of composite sheet)
The prepared laminated sheet was fixed in the mold with the grooved surface up, and urethane resin pellets (Resamine P-6165, manufactured by Dainichi Seika Kogyo Co., Ltd.) were filled in the groove and on the tin sheet. 150 ° C., 1 MPa) to melt the pellets. Further, the resin region X was formed by heat-compressing for 10 minutes and then cooling while maintaining the pressure to solidify the urethane resin. Thereafter, in order to increase the thickness accuracy, the surface of the resin region X was buffed to prepare a composite sheet. The D hardness of the resin region X was 28 degrees, and the thickness from the tin sheet surface was 2.3 mm. Then, the double-sided tape was affixed on the resin area | region X, and the composite sheet with a double-sided tape was produced.

(Preparation of polishing layer)
A number of through holes B (12 mm in diameter) were formed in the composite sheet with double-sided tape as shown in FIG. Thereafter, as shown in FIG. 5, the composite sheet with the double-sided tape is punched out to a diameter of about 76 cm so as to provide two anode connecting protrusions (length L: 25.4 mm, width W: 63.5 mm). A polishing layer with a double-sided tape was prepared. And the polyurethane foam layer of the protrusion part for anode connection was peeled, and the tin sheet was exposed. Further, using a groove processing machine, XY lattice-shaped (groove width 2.0 mm, groove pitch 16 mm, groove depth 300 μm) grooves were processed on the resin layer on the polishing layer surface. The thickness of the polishing layer was about 2 mm. The total surface area of the tin region was about 44% with respect to the surface area of the polishing layer, and the total surface area of the through holes B was about 13% with respect to the surface area of the polishing layer.

(Preparation of polishing pad)
A Cu mesh (made of mesh, thickness: 0.14 mm) as a cathode layer was bonded to the double-sided tape of the produced polishing layer with double-sided tape using a laminator. And the double-sided tape was bonded together to Cu mesh using the laminating machine. Then, a cushion layer (manufactured by Rogers Corporation, PORON, thickness: 2.5 mm) was bonded to the double-sided tape using a laminator. Further, a double-sided tape was bonded to the cushion layer using a laminator. Finally, magnetic SUS (SUS410, thickness: 0.6 mm) was bonded to the double-sided tape to produce a polishing pad.

Example 2
Example in which a thermoplastic polyurethane elastomer sheet (manufactured by Dainichi Seika, P-2275 (sheet molded by extrusion method), thickness 1.00 mm, Asker D hardness: 30 degrees) was used instead of the polyurethane foam layer A polishing pad was prepared in the same manner as in 1.

Comparative Example 1
A container was charged with 19000 g of DMF, 1000 g of KB (manufactured by LION, Ketjen Black), and 35000 g of 2 mmφ balls, and mixed in a ball mill at 400 rpm for 20 minutes. To the obtained primary mixed solution, 11660 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-pressed for 1 minute (temperature: 190 ° C., pressure: 10 MPa) to obtain a polishing layer (thickness: 1.95 mm). 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 about 15% of the grinding | polishing surface using the hole processing machine. Thereafter, the laminated sheet was punched out with a diameter of about 61 cm (24 inches).

  Thereafter, a Cu mesh (made of mesh, thickness: 0.14 mm) as a cathode layer 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, a cushion 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 cushion layer to prepare a polishing pad.

  From the above results, the polishing pad of the present invention has 1) excellent flattening characteristics, 2) extremely low surface electrical resistance, and easy dissolution and removal of the metal film on the wafer surface. It can be seen that the generation of scratches can be effectively suppressed. Comparative Example 1 has a low polishing rate due to low conductivity, and has many scratches due to carbon black desorption.

Schematic process drawing showing an example of a method for producing a polishing pad of the present invention Schematic showing the surface structure of the polishing layer of the present invention 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 Schematic surface view showing a polishing layer having two anode connecting protrusions

Explanation of symbols

1: Polishing pad 2: Polishing layer 3: Cathode layer (copper mesh)
4: Resin layer 5: Adhesive layer (double-sided tape)
6: Polishing surface plate 7: Material to be polished (semiconductor wafer)
8: Support base (polishing head)
9: Voltage application unit 10: Electrolytic solution 11: Resin layer with adhesive layer 12: Through hole A
13: Tin sheet 14: Flexible sheet 15: Groove 16: Laminated sheet 17: Tin region 18: Viscoelastic material 19: Resin region X
20: Composite sheet 21: Through hole B
22: Cushion layer 23: Magnetic layer 24: Electrolytic solution groove 25: Projection for anode connection

Claims (6)

A step of forming a large number of through holes A in a resin layer with an adhesive layer having an adhesive layer on one side, a tin sheet and a flexible sheet are laminated in this order on the adhesive layer of the resin layer to form a laminate , Pressing the laminate and laminating a tin sheet along the through-hole A to produce a laminated sheet having a groove on the tin sheet surface; forming a resin region X in the groove and on the tin sheet surface to form a composite A method for producing a polishing pad, comprising: a step of forming a sheet; and a step of forming a through hole B penetrating from the resin layer to the resin region X in the composite sheet. The method for producing a polishing pad according to claim 1, wherein the resin layer is a polyurethane layer. The method for producing a polishing pad according to claim 1, wherein the resin layer is a polyurethane foam layer. The method for producing a polishing pad according to any one of claims 1 to 3, wherein a raw material of the resin region X is a thermosetting polyurethane resin, a thermoplastic polyurethane resin, or a polyurethane-based thermoplastic elastomer. The method for producing a polishing pad according to claim 1, wherein the flexible sheet has a hardness lower than that of the resin layer. The thickness of the said flexible sheet is a manufacturing method of the polishing pad in any one of Claims 1-5 larger than the thickness of the resin layer with an adhesive bond layer.

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