JP5100241B2 - Polishing pad and manufacturing method thereof - Google Patents

Description

  The present invention stabilizes flattening processing of optical materials such as lenses and reflecting mirrors, silicon wafers, glass substrates for hard disks, aluminum substrates, and materials that require high surface flatness such as general metal polishing processing, The present invention also relates to a polishing pad that can be performed with high polishing efficiency and a method for manufacturing the same. The polishing pad of the present invention is a step (rough polishing) of a silicon wafer and a device on which an oxide layer, a metal layer, etc. are formed, before further laminating and forming these oxide layers and metal layers. It is preferably used in the step). The polishing pad of the present invention is also suitably used for finish polishing the surface of the material, and is particularly useful for finish polishing of silicon wafers and glass.

  When manufacturing a semiconductor device, a step of forming a conductive layer on the wafer surface and forming a wiring layer by photolithography, etching, or the like, or a step of forming an interlayer insulating film on the wiring layer These steps cause irregularities made of a conductor such as metal or an insulator on the wafer surface. In recent years, miniaturization of wiring and multilayer wiring have been advanced for the purpose of increasing the density of semiconductor integrated circuits, and along with this, technology for flattening the irregularities on the wafer surface has become important.

  As a method for flattening the irregularities on the wafer surface, chemical mechanical polishing (hereinafter referred to as CMP) is generally employed. CMP is a technique of polishing using a slurry-like abrasive (hereinafter referred to as slurry) in which abrasive grains are dispersed in a state where the surface to be polished of a wafer is pressed against the polishing surface of a polishing pad. As shown in FIG. 1, for example, a polishing apparatus generally used in CMP includes a polishing surface plate 2 that supports a polishing pad 1 and a support base (polishing head) 5 that supports a material to be polished (semiconductor wafer) 4. And a backing material for uniformly pressing the wafer, and an abrasive supply mechanism. The polishing pad 1 is attached to the polishing surface plate 2 by attaching it with a double-sided tape, for example. The polishing surface plate 2 and the support base 5 are disposed so that the polishing pad 1 and the material to be polished 4 supported by each of the polishing surface plate 2 and the support base 5 are opposed to each other, and are provided with rotating shafts 6 and 7 respectively. Further, a pressurizing mechanism for pressing the workpiece 4 against the polishing pad 1 is provided on the support base 5 side.

  Conventionally, such a polishing pad is produced by 1) pouring a resin material into a mold to produce a resin block, and slicing the resin block with a slicer, and 2) pouring the resin material into the mold and pressing it. Thus, it has been produced by a batch method such as a method for producing a thin sheet, and 3) a method in which a resin as a raw material is dissolved and extruded from a T-die and directly produced into a sheet. For example, in Patent Document 1, a polishing pad is manufactured by a reaction injection molding method.

  In addition, in the case of a laminated polishing pad, since it was manufactured by bonding a plurality of resin sheets such as a polishing layer and a cushion layer obtained by the above method with an adhesive or a double-sided tape, there are many manufacturing steps and productivity is poor. Had the problem. In order to solve the problem, in Patent Document 2, a laminated polishing pad is manufactured using an extruder.

  In addition, a method for continuously producing a polyurethane / polyurea abrasive sheet material has been proposed in order to prevent variations in hardness, bubble size, and the like due to a batch production method (Patent Document 3). Specifically, a polyurethane raw material is mixed with a fine powder having a particle size of 300 μm or less and an organic foaming agent, and the mixture is discharged and cast between a pair of endless track belts. Thereafter, a polymerization reaction of the mixture is performed by a heating means, and the produced sheet-like molded product is separated from the face belt to obtain an abrasive sheet material.

  On the other hand, a polyurethane foam sheet is generally used as a polishing pad used for high-precision polishing. However, although the polyurethane foam sheet is excellent in local flattening ability, it is difficult to apply a uniform pressure to the entire wafer surface because of insufficient cushioning properties. For this reason, usually, a soft cushion layer is separately provided on the back surface of the polyurethane foam sheet, and is used for polishing as a laminated polishing pad. For example, the following polishing pads have been developed.

  A polishing pad is disclosed in which a relatively hard first layer and a relatively soft second layer are laminated, and a groove having a predetermined pitch or a protrusion having a predetermined shape is provided on the polishing surface of the first layer. (Patent Document 4).

  Also, a first sheet-like member having elasticity and having irregularities formed on the surface, and a surface that is provided on the surface of the first sheet-like member on which the irregularities are formed and that faces the surface to be polished of the substrate to be processed. A polishing cloth having a second sheet-like portion is disclosed (Patent Document 5).

  Furthermore, a polishing pad is disclosed that includes a polishing layer and a support layer that is laminated on one surface of the polishing layer and is a foam having a higher compressibility than the polishing layer (Patent Document 6).

  However, since the conventional laminated polishing pad is manufactured by bonding the polishing layer and the cushion layer with a double-sided tape (adhesive layer), the slurry enters between the polishing layer and the cushion layer during polishing. As a result, the adhesive force of the double-sided tape is weakened, and as a result, the polishing layer and the cushion layer are peeled off.

  Also, a method for continuously producing a polishing pad having an underlayer and a polishing layer has been disclosed for the purpose of reducing the difference between polishing pads (Patent Document 7). Specifically, there is a method in which a fluid phase polymer composition is supplied onto the transferred underlayer, and then the fluid phase polymer composition is cured and attached to the underlayer to form a solid phase polishing layer. Proposed. According to the manufacturing method, since the solid phase polishing layer and the base layer are directly laminated without using a double-sided tape or the like, it is possible to prevent peeling between the two members. However, the polishing pad usually needs to be provided with a double-sided tape for mounting on the polishing surface plate. In the manufacturing method described above, it is necessary to attach a double-sided tape to the other surface of the underlayer. In this case, however, there remains a problem that the underlayer and the double-sided tape are peeled off. In addition, when the fluid phase polymer composition is cured to form a solid phase polishing layer, there is also a problem that the solid phase polishing layer shrinks due to curing and the polishing pad tends to warp.

JP 2004-42189 A JP 2003-220550 A JP 2004-169038 A JP 2003-53657 A JP-A-10-329005 JP 2004-25407 A Special table 2003-516872 gazette

  An object of this invention is to provide the polishing pad which is hard to peel between each member of a polishing layer, a cushion layer, and an adhesive sheet, and its manufacturing method.

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

  That is, the present invention provides a polishing pad having at least a polishing layer and a cushion layer, wherein one side of the cushion layer is directly bonded to the polishing layer by self-adhesion, and the other side of the cushion layer is a resin sheet. It is related with the polishing pad characterized by adhere | attaching directly to this resin sheet of the adhesive sheet which has an adhesion layer in the single side | surface by self-adhesion.

  In the polishing pad of the present invention, since the members of the polishing layer, the cushion layer, and the pressure-sensitive adhesive sheet are directly bonded without using an adhesive member such as a double-sided tape, the adhesive strength between the members is very strong, Even when the polishing operation is performed using the slurry for a long period of time, there is no separation between the members.

  The polishing layer is preferably made of a thermosetting polyurethane foam having an closed cell structure with an average cell diameter of 30 to 70 μm and an Asker D hardness of 40 to 70 degrees. When the average bubble diameter deviates from this range, the polishing rate tends to decrease or the planarity (flatness) of the polished material (wafer) after polishing tends to decrease. Further, when the Asker D hardness is less than 40 degrees, the planarity of the material to be polished is lowered. When the Asker D hardness is more than 70 degrees, the planarity is good, but the uniformity (uniformity) of the material to be polished is lowered. There is a tendency.

  The cushion layer is preferably made of a thermosetting polyurethane foam having an open cell structure with an average cell diameter of 30 to 200 μm and an Asker C hardness of 10 to 80 degrees. When the average cell diameter deviates from this range, the function as a cushion layer tends to be insufficient. Further, when the Asker C hardness is less than 10 degrees, the thickness variation of the cushion layer becomes large at the time of production, and there is a tendency that stable polishing characteristics cannot be obtained. On the other hand, when the angle exceeds 80 degrees, the followability of the polishing pad with respect to the wafer tends to deteriorate and the in-plane uniformity tends to deteriorate. Moreover, by making the thermosetting polyurethane foam, which is a material for forming the cushion layer, into an open-cell structure, shrinkage of the cushion layer during curing can be suppressed and warping of the polishing pad can be prevented.

  The present invention also includes a step of continuously discharging a cell-dispersed urethane composition onto the polishing layer while feeding the polishing layer, and cell-dispersing an adhesive sheet having an adhesive layer on one side of the resin sheet on the cell-dispersed urethane composition. Including a step of laminating the urethane composition and the resin sheet so as to contact each other and a step of forming a cushion layer made of a thermosetting polyurethane foam by curing the cell-dispersed urethane composition while uniformly adjusting the thickness. The present invention relates to a method for manufacturing a polishing pad.

  According to the said manufacturing method, each member of a polishing layer, a cushion layer, and an adhesive sheet can manufacture the polishing pad which has adhere | attached directly without interposing adhesive members, such as a double-sided tape, with sufficient productivity. In addition, by forming a cushion layer on a highly rigid polishing layer, warping of the polishing pad can be suppressed even when the cushion layer shrinks during curing.

  The polishing layer of the polishing pad in the present invention is not particularly limited as long as it is a foam having a closed cell structure. Examples of the foam material include polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, and olefin resin (polyethylene). , Polypropylene, etc.), epoxy resins, photosensitive resins and the like, or a mixture of two or more. A thermosetting polyurethane resin is particularly preferable as a material for forming a polishing layer because it has excellent wear resistance and a polymer having desired physical properties can be easily obtained by variously changing the raw material composition. Hereinafter, a thermosetting polyurethane resin (hereinafter referred to as a polyurethane resin) will be described on behalf of the foam.

  The polyurethane resin is composed of an isocyanate component, a polyol component (high molecular weight polyol, 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 polycarbonate 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.

  Along with high molecular weight polyol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, tri Methylolpropane, glycerin, 1,2,6-hexanetriol, pentaerythritol, tetramethylolcyclohexane, methyl glucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl) cyclo Hexanol, diethanolamine, N- methyldiethanolamine, and low molecular weight polyols such as triethanolamine may be used in combination. 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, 1,2-bis (2-aminophenylthio) ethane, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyl Diphenylmethane, N, N′-di-sec-butyl-4,4′-diaminodiphenylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, m-xyl And polyamines exemplified by N, N'-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and p-xylylenediamine, or the above-mentioned low molecular weight polyols and low molecular weight polyamines. be able to. These may be used alone or in combination of two or more.

  The ratio of the isocyanate component, the polyol component, and the chain extender can be variously changed depending on the molecular weight of each and the desired physical properties of the polishing layer. In order to obtain a polishing layer having desired polishing characteristics, the number of isocyanate groups of the isocyanate component relative to the total number of active hydrogen groups (hydroxyl group + amino group) of the polyol component and the chain extender is 0.80 to 1.20. Is more preferable, and 0.99 to 1.15 is more preferable. When the number of isocyanate groups is outside the above range, curing failure occurs and the required specific gravity and hardness cannot be obtained, and the polishing characteristics tend to be deteriorated.

  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. The method is suitable because the physical properties of the resulting polyurethane are excellent.

  Examples of the method for producing the polyurethane foam include a method of adding hollow beads, a mechanical foaming method (including a mechanical floss method), and a chemical foaming method.

  In particular, a mechanical foaming method using a silicon surfactant is preferable. Examples of suitable silicon surfactants include SH-192 (manufactured by Toray Dow Corning Silicone), B-8443, B-8465 (manufactured by Goldschmidt), and the like. The silicon-based surfactant is preferably added to the polyurethane foam in an amount of 0.1 to 10% by weight, and more preferably 0.5 to 7% by weight. When the amount of the silicon-based surfactant is less than 0.1% by weight, a fine-bubble foam tends to be not obtained. On the other hand, when it exceeds 10% by weight, a polyurethane foam having a high hardness tends to be difficult to obtain due to the plasticizing effect of the surfactant.

An example of a method for producing a polishing layer made of polyurethane foam will be described below. The manufacturing method of this polishing layer has the following steps.
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 step The above foaming reaction liquid is poured into a long mold.
4) Curing step The foaming reaction solution poured into the long 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 order to obtain the target polyurethane foam, the rotational speed of the stirring blade is preferably 500 to 2000 rpm, more preferably 800 to 1500 rpm. The stirring time is appropriately adjusted according to the target density.

  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 a long mold and immediately put into a heating oven for post cure, and since heat is not immediately transferred to the reaction components even under such conditions, the bubble diameter may increase. Absent. The curing reaction is preferably performed at normal pressure because the bubble shape is stable.

  Also, a polyurethane foam is prepared by preparing a foaming reaction liquid by a mechanical flossing method, continuously discharging the foaming reaction liquid onto the face material while curing the foaming reaction liquid while uniformly adjusting the thickness. A polishing layer made of may be continuously produced.

  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 70 μm, more preferably 30 to 60 μm.

  The specific gravity of the polyurethane foam is preferably 0.5-1. When the specific gravity is less than 0.5, the surface strength of the polishing layer decreases, and the planarity of the material to be polished tends to decrease. On the other hand, when it is larger than 1, the number of bubbles on the surface of the polishing layer is reduced, and planarity is good, but the polishing rate tends to decrease.

  The polyurethane foam preferably has a hardness of 40 to 70 degrees, more preferably 45 to 65 degrees as measured by an Asker D hardness meter.

  The thickness of the polishing layer is not particularly limited, but is usually about 0.5 to 4 mm, and preferably 1 to 2.5 mm. The width of the polishing layer is not particularly limited, but is about 60 to 250 cm in consideration of the required polishing pad size.

  The polishing surface of the polishing layer preferably has a concavo-convex structure for holding and updating the slurry. The polishing layer made of foam has many openings on the polishing surface and has the function of holding and updating the slurry. By forming a concavo-convex structure on the polishing surface, the slurry can be held and updated more efficiently. It can be performed well, and destruction of the material to be polished due to adsorption with the material to be polished can be prevented. The concavo-convex structure is not particularly limited as long as it is a shape that holds and renews slurry. For example, an X (striped) groove, an XY lattice groove, a concentric groove, a through hole, a hole that does not pass through, a polygonal column, Examples include a cylinder, a spiral groove, an eccentric circular groove, a radial groove, and a combination of these grooves. In addition, these uneven structures are generally regular, but in order to make the slurry retention and renewability desirable, the groove pitch, groove width, groove depth, etc. should be changed for each range. Is also possible.

  The method for producing the concavo-convex structure is not particularly limited. For example, a method of machine cutting using a jig such as a tool of a predetermined size, a method of pressing a resin with a press plate having a predetermined surface shape And a method of producing by photolithography, a method of producing by using a printing method, a method of producing by laser light using a carbon dioxide gas laser, and the like.

  The cushion layer is not particularly limited as long as it is a foam that is softer than the polishing layer. Examples of the material for forming the cushion layer include polyurethane resin, polyester resin, polyamide resin, acrylic resin, olefin resin (polyethylene, polypropylene, etc.), photosensitive resin, or a mixture thereof. When the polishing layer is formed of a polyurethane resin, it is preferable to use a polyurethane resin as a material for forming the cushion layer from the viewpoint of improving adhesiveness. Hereinafter, the polyurethane resin will be described as a representative material for forming the cushion layer.

  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, polymeric MDI, carbodiimide-modified MDI ( For example, trade name Millionate MTL, manufactured by Nippon Polyurethane Industry), 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate and other aromatic diisocyanates, ethylene diisocyanate, Aliphatic diisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate and 1,6-hexamethylene diisocyanate , 1,4-cyclohexane diisocyanate, cyclohexane diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, isophorone diisocyanate, and cycloaliphatic diisocyanates such as norbornane diisocyanate. These may be used alone or in combination of two or more.

  High molecular weight polyols similar to those described above can be used. In particular, it is preferable to use a high molecular weight polyol having a hydroxyl value of 20 to 200 mgKOH / g. When the hydroxyl value is less than 20 mgKOH / g, the polyurethane resin becomes too soft and the durability tends to decrease. On the other hand, when the hydroxyl value exceeds 200 mgKOH / g, the elastic properties of the polyurethane resin tend to deteriorate and the cushioning property tends to deteriorate.

  The low molecular weight polyol or the like may be used in combination with the high molecular weight polyol. These low molecular weight polyols may be used alone or in combination of two or more.

  The ratio of the high molecular weight polyol to the low molecular weight polyol in the polyol component is determined by the properties required for the cushion layer produced therefrom.

  In order to make the polyurethane foam into an open cell structure, the low molecular weight polyol, the low molecular weight polyamine, and the alcohol amine are preferably contained in the active hydrogen-containing compound in a total amount of 2 to 15% by weight, more preferably 5 to 10%. % By weight. By using a specific amount of the low molecular weight polyol or the like, not only the bubble film is easily broken and it becomes easy to form open cells, but also the cushioning property of the polyurethane foam is improved.

  In order to make the polyurethane foam into an open-cell structure, it is preferable to use a polymer polyol, and it is particularly preferable to use a polymer polyol in which polymer particles made of acrylonitrile and / or a styrene-acrylonitrile copolymer are dispersed. The polymer polyol is preferably contained in the total high molecular weight polyol to be used in an amount of 20 to 100% by weight, more preferably 30 to 60% by weight.

  The ratio of the isocyanate component, the polyol component, and the chain extender can be variously changed depending on the molecular weight of each, the desired physical properties of the cushion layer, and the like. In order to obtain a cushion layer having desired polishing characteristics, the number of isocyanate groups of the isocyanate component relative to the total number of active hydrogen groups (hydroxyl group + amino group) of the polyol component and the chain extender is 0.80 to 1.20. Is more preferable, and 0.99 to 1.15 is more preferable. When the number of isocyanate groups is outside the above range, curing failure occurs and the required specific gravity and hardness cannot be obtained, and the cushioning property tends to be lowered.

  The polyurethane foam can be produced by either the prepolymer method or the one-shot method.

  When a polyurethane foam is produced by a prepolymer method, a chain extender is used for curing the prepolymer. As the chain extender, the same ones as described above can be used.

  Hereinafter, the polishing pad manufacturing method of the present invention will be described in detail with reference to FIG. FIG. 2 is a process diagram showing an example of a method for producing a polishing pad according to the present invention.

  The polishing layer 9 sent out from the supply roll 8 moves on the non-movable plate 10. First, the cell-dispersed urethane composition 11 as a cushion layer forming material is continuously discharged onto the polishing layer 9 from the discharge port of the mixing head 12. A belt conveyor may be used instead of the non-movable plate, but it is preferable to use a non-movable plate from the viewpoint of increasing the thickness accuracy of the cushion layer.

  The cell dispersed urethane composition 11 is prepared by a mechanical foaming method (including a mechanical floss method). For example, the cell-dispersed urethane composition is prepared by the following method.

  (1) The first component obtained by adding a silicon surfactant to an isocyanate-terminated prepolymer obtained by reacting an isocyanate component and a high molecular weight polyol is mechanically stirred in the presence of a non-reactive gas, and the non-reactive gas is removed. Disperse as fine bubbles to obtain a cell dispersion. Then, a second component containing an active hydrogen-containing compound such as a high molecular weight polyol or a low molecular weight polyol is added to the cell dispersion and mixed to prepare a cell dispersed urethane composition.

  (2) A component in which a silicon-based surfactant is added to at least one of a first component containing an isocyanate component (or an isocyanate-terminated prepolymer) and a second component containing an active hydrogen-containing compound, and a silicon-based surfactant is added Is mechanically stirred in the presence of a non-reactive gas to disperse the non-reactive gas as fine bubbles to obtain a bubble dispersion. Then, the remaining components are added to the cell dispersion and mixed to prepare a cell-dispersed urethane composition.

  (3) A silicon-based surfactant is added to at least one of the first component containing the isocyanate component (or isocyanate-terminated prepolymer) and the second component containing the active hydrogen-containing compound, and the first component and the second component are added. A foam-dispersed urethane composition is prepared by mechanically stirring in the presence of a non-reactive gas and dispersing the non-reactive gas as fine bubbles.

  The cell dispersed urethane composition may be prepared by a mechanical floss method. The mechanical floss method is a method in which raw material components are put into a mixing chamber of a mixing head and a non-reactive gas is mixed and mixed and stirred by a mixer such as an Oaks mixer to make the non-reactive gas into a fine bubble state in the raw material mixture. It is a method of dispersing in. The mechanical floss method is a preferable method because the density of the polyurethane foam can be easily adjusted by adjusting the amount of the non-reactive gas mixed therein. Moreover, since the polyurethane foam which has a fine bubble with an average cell diameter of 30-200 micrometers can be continuously shape | molded, manufacturing efficiency is good.

  As the silicon-based surfactant, the same ones as described above can be used. The silicon-based surfactant is preferably added in an amount of 0.1 to 10% by weight, more preferably 0.5 to 7% by weight, in the cell-dispersed urethane composition. When the amount of the silicon-based surfactant is less than 0.1% by weight, a fine-bubble foam tends to be not obtained. On the other hand, when it exceeds 10% by weight, the surfactant tends to bleed and the self-adhesive strength tends to decrease.

  As the non-reactive gas used for forming the fine bubbles, the same as described above can be used. Also, the same stirring device as described above can be used for dispersing the non-reactive gas in the form of fine bubbles.

  Thereafter, the pressure-sensitive adhesive sheet 13 having an adhesive layer on one side of the resin sheet is laminated on the cell-dispersed urethane composition 11 so that the cell-dispersed urethane composition and the resin sheet are in contact with each other. The thickness of 11 is adjusted uniformly. The adhesive sheet 13 is a member for attaching the polishing pad to the polishing surface plate.

  Examples of the resin forming the resin sheet of the pressure-sensitive adhesive sheet 13 include polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, polyfluoroethylene, and other fluorine-containing resins, nylon, and cellulose. be able to. Of these, it is preferable to use polyethylene terephthalate having a low coefficient of thermal expansion.

  Although the thickness in particular of a resin sheet is not restrict | limited, It is preferable that it is about 20-200 micrometers from viewpoints, such as intensity | strength and winding-up. The width of the resin sheet is not particularly limited, but is preferably about 60 to 250 cm in consideration of the required polishing pad size.

  The composition in particular of an adhesion layer is not restrict | limited, For example, a rubber adhesive, an acrylic adhesive, etc. are mentioned.

  Examples of the thickness adjusting means include a blade 14 such as a doctor blade; a roll such as a nip roll and a coater roll. The thickness adjustment must be performed before the fluidity of the cell-dispersed urethane composition is lost.

  Thereafter, the foam-dispersed urethane composition whose thickness is adjusted in the previous step is cured to form a cushion layer made of a polyurethane foam, thereby producing an abrasive sheet. Curing of the cell-dispersed urethane composition is performed, for example, by passing through a heating oven 15 provided on a non-movable plate. The heating temperature is about 40 to 100 ° C., and the heating time is about 5 to 60 minutes. The heat source may be provided only above or below the non-movable fixed plate, and may be provided above and below, but is preferably provided above and below to make the thermal expansion of the polishing layer 9 and the pressure-sensitive adhesive sheet 13 comparable. . Thereby, a polishing pad having no warpage and excellent thickness accuracy can be produced.

  It is preferable that the average cell diameter of a polyurethane foam is 30-200 micrometers, More preferably, it is 30-100 micrometers.

  The obtained abrasive sheet is primarily cut into a shape slightly larger than a desired shape (for example, a circular shape, a square shape, a rectangular shape, a fabric having a length of several meters) by a cutting machine. Thereafter, a polishing pad is produced through a post-cure process or the like. Post-curing has the effect of improving the physical properties of the polyurethane foam. After the post cure, the abrasive sheet is secondarily cut according to a desired shape. In the case of cutting into a circle, the diameter is about 50 to 200 cm, preferably 50 to 100 cm. When cutting into a square, one side is about 50 to 200 cm, preferably 50 to 100 cm. When cutting into a rectangle, the width is about 50 to 200 cm, preferably 50 to 100 cm, and the length is about 1.1 to 2 times the width. When cutting into a fabric, the length is appropriately adjusted according to the polishing apparatus to be used, but is usually about 5 to 10 m.

  Although the thickness of a cushion is not specifically limited, Usually, it is about 0.5-1.5 mm, and it is preferable that it is 0.5-1 mm. The width of the cushion layer is not particularly limited, but is preferably about 60 to 250 cm in consideration of the required polishing pad size.

  The specific gravity of the cushion layer is preferably 0.2 to 0.6. When the specific gravity is less than 0.2, the durability of the cushion layer tends to decrease. Moreover, when larger than 0.6, it exists in the tendency for cushioning properties to worsen.

  The cushion layer preferably has an Asker C hardness of 10 to 80 degrees, more preferably 20 to 70 degrees.

  The semiconductor device is manufactured through a step of polishing the surface of the semiconductor wafer using the polishing pad. A semiconductor wafer is generally a laminate of a wiring metal and an oxide film on a silicon wafer. The method and apparatus for polishing the semiconductor wafer are not particularly limited. For example, as shown in FIG. 1, a polishing surface plate 2 that supports the polishing pad 1, a support table (polishing head) 5 that supports the semiconductor wafer 4, and the wafer. This is performed using a backing material for performing uniform pressurization and a polishing apparatus equipped with a polishing agent 3 supply mechanism. The polishing pad 1 is attached to the polishing surface plate 2 by attaching it with a double-sided tape, for example. The polishing surface plate 2 and the support base 5 are disposed so that the polishing pad 1 and the semiconductor wafer 4 supported on each of the polishing surface plate 2 and the support table 5 face each other, and are provided with rotating shafts 6 and 7 respectively. Further, a pressurizing mechanism for pressing the semiconductor wafer 4 against the polishing pad 1 is provided on the support base 5 side. In polishing, the semiconductor wafer 4 is pressed against the polishing pad 1 while rotating the polishing surface plate 2 and the support base 5, and polishing is performed while supplying slurry. The flow rate of the slurry, the polishing load, the polishing platen rotation speed, and the wafer rotation speed are not particularly limited and are appropriately adjusted.

  Thereby, the surface roughness of the surface of the semiconductor wafer 4 is improved, and scratches are removed. 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. Further, a glass substrate for a lens or hard disk can be finished and polished by the same method as described above.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[Measurement and evaluation methods]
(Average bubble diameter)
The prepared polishing layer and cushion layer were cut as thin as possible to a thickness of 1 mm or less in parallel with a microtome cutter and used as samples for measuring the average cell diameter. The sample was fixed on a slide glass and observed at 100 times using SEM (S-3500N, Hitachi Science Systems, Ltd.). Using the image analysis software (WinRoof, Mitani Shoji Co., Ltd.) for the obtained image, the total bubble diameter in an arbitrary range was measured, and the average bubble diameter was calculated.

(specific gravity)
This was performed according to JIS Z8807-1976. The produced polishing layer and cushion layer were cut into 4 cm × 8.5 cm strips (thickness: arbitrary) and used as a sample for measuring specific gravity, and the temperature was 23 ° C. ± 2 ° C. and the humidity was 50% ± 5% for 16 hours. Left to stand. The specific gravity was measured using a hydrometer (manufactured by Sartorius).

(D hardness)
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 temperature 23 ° C. ± 2 ° C. and humidity 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).

(C hardness)
This was performed according to JIS K-7312. The produced cushion layer was cut into a size of 5 cm × 5 cm (thickness: arbitrary) and used as a sample, which 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 have a thickness of 10 mm or more. Using a hardness meter (manufactured by Kobunshi Keiki Co., Ltd., Asker C type hardness meter, pressure surface height: 3 mm), the hardness 60 seconds after contacting the pressure surface was measured.

Example 1
(Preparation of polishing layer)
Toluene diisocyanate (mixture of 2,4-isomer / 2,6-isomer = 80/20) 32 parts by weight, 4,4′-dicyclohexylmethane diisocyanate 8 parts by weight, polytetramethylene glycol (number average molecular weight: 1006) 54 parts by weight And 6 parts by weight of diethylene glycol were mixed and heated and stirred at 80 ° C. for 120 minutes to prepare an isocyanate-terminated prepolymer (isocyanate equivalent: 2.1 meq / g). 100 parts by weight of the isocyanate-terminated prepolymer and 3 parts by weight of a silicon surfactant (SH-192, manufactured by Toray Dow Corning Silicone Co., Ltd.) were mixed to prepare a mixture whose temperature was adjusted to 80 ° C. 80 parts by weight of the mixture and 20 parts by weight of 4,4′-methylenebis (o-chloroaniline) (Ihara Chemical Amine, Iharacamine MT) melted at 120 ° C. were mixed in a mixing chamber and air was mixed at the same time. A cell-dispersed urethane composition A was prepared by mechanically stirring the mixture therein.

  The cell-dispersed urethane composition A was continuously discharged onto the face material while feeding the face material (thickness: 188 μm, width: 100 cm) made of a PET film and subjected to a peeling treatment. Then, the cell-dispersed urethane composition A was covered with another face material (thickness: 188 μm, width: 100 cm) made of a PET film and subjected to a peeling treatment, and the thickness was uniformly adjusted using a nip roll. Thereafter, the composition was cured by heating to 80 ° C. to prepare a long polishing layer (thickness: 1.5 mm) made of a polyurethane foam having a closed cell structure. Thereafter, the face material was peeled off from the polishing layer and post-cured at 100 ° C. for 6 hours. Next, the polishing layer was surface buffed using a buffing machine (manufactured by Amitech) to adjust the thickness accuracy to 1.27 mm. And the groove | channel process was given to the grinding | polishing surface of this grinding | polishing layer using the groove processing machine (made by Toho Steel Machine). The polishing layer had an average cell diameter of 50 μm, a specific gravity of 0.86, and a D hardness of 55 degrees.

(Preparation of polishing pad)
50 parts by weight of POP36 / 28 (manufactured by Mitsui Chemicals, polymer polyol, hydroxyl value: 28 mgKOH / g), 25 parts by weight of PCL210 (manufactured by Daicel Chemical Industries, polyester polyol, hydroxyl value: 112 mgKOH / g), diethylene glycol 5 parts by weight, 20 parts by weight of PCL 312 (manufactured by Daicel Chemical Industries, Ltd., polyester polyol, hydroxyl value: 134 mg KOH / g), 6 parts by weight of a silicon surfactant (manufactured by Goldschmidt, B-8443), and catalyst (No .25, manufactured by Kao Corporation) 0.25 part by weight was added and mixed to prepare a mixture whose temperature was adjusted to 40 ° C. 106 parts by weight of the mixture and 35.2 parts by weight of Millionate MTL (manufactured by Nippon Polyurethane Industry) were mixed in a mixing chamber, and at the same time, air was mechanically stirred to disperse the foam-dispersed urethane composition B. Was prepared.

  The prepared cell-dispersed urethane composition B was discharged onto the polishing layer while feeding the prepared polishing layer onto a non-movable plate. Then, the cell-dispersed urethane composition B and the polyethylene terephthalate sheet are contacted with the pressure-sensitive adhesive sheet (width 100 cm) having an acrylic adhesive layer on one side of the polyethylene terephthalate sheet (thickness 0.2 mm) on the cell-dispersed urethane composition B. I put it on. The cell-dispersed urethane composition B was made to a thickness of 1.0 mm with a nip roll, and then cured at 70 ° C. for 40 minutes to form a cushion layer made of polyurethane foam having an open-cell structure to prepare an abrasive sheet. The cushion layer had an average cell diameter of 70 μm, a specific gravity of 0.34, and a C hardness of 23 degrees. Further, one side of the cushion layer was firmly adhered to the polishing layer by self-adhesion, and the other surface of the cushion layer was firmly adhered to the polyethylene terephthalate sheet of the pressure-sensitive adhesive sheet by self-adhesion. The prepared polishing sheet was primarily cut at 80 cm square and then post-cured at 80 ° C. for 6 hours. Thereafter, the polishing pad was produced by secondary cutting into a size of 70 cm in diameter.

Schematic configuration diagram showing an example of a polishing apparatus used in CMP polishing Schematic showing the manufacturing process of the polishing pad of the present invention

Explanation of symbols

1: Polishing pad 2: Polishing surface plate 3: Abrasive (slurry)
4: Material to be polished (semiconductor wafer)
5: Support base (polishing head)
6, 7: Rotating shaft 8: Supply roll 9: Polishing layer 10: Non-movable fixed plate 11: Cell-dispersed urethane composition 12: Mixing head 13: Adhesive sheet 14: Blade 15: Heating oven

Claims (5)

A step of continuously discharging a cell-dispersed urethane composition prepared by a mechanical foaming method while delivering a polishing layer, and a cell-dispersed adhesive sheet having an adhesive layer on one side of a resin sheet on the cell-dispersed urethane composition Including a step of laminating the urethane composition and the resin sheet so as to contact each other and a step of forming a cushion layer made of a thermosetting polyurethane foam by curing the cell-dispersed urethane composition while uniformly adjusting the thickness. Manufacturing method of polishing pad. 2. The cell-dispersed urethane composition contains an isocyanate component, an active hydrogen-containing compound containing a high molecular weight polyol, and a silicon-based surfactant, and the hydroxyl value of the high molecular weight polyol is 20 to 200 mgKOH / g. Method of manufacturing a polishing pad. The cell-dispersed urethane composition includes an isocyanate component, an active hydrogen-containing compound containing a high molecular weight polyol, and a silicon surfactant, and the high molecular weight polyol is a polymer particle made of acrylonitrile and / or a styrene-acrylonitrile copolymer. The manufacturing method of the polishing pad of Claim 1 which contains 20-100 weight% of polymer polyols in which is dispersed. 4. The method for producing a polishing pad according to claim 2, wherein the active hydrogen-containing compound contains 2 to 15 wt% in total of at least one of a low molecular weight polyol, a low molecular weight polyamine, and an alcohol amine. The method for producing a polishing pad according to any one of claims 1 to 4, wherein the cushion layer is made of a thermosetting polyurethane foam having an average cell diameter of 30 to 200 µm and an open cell structure having an Asker C hardness of 10 to 80 degrees. .

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