JP2011212794A - Polishing pad, method of manufacturing the same, and method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad with which a drop in dressing speed can be prevented and microscopic undulations that occur on the surface of an object to be polished can be reduced, a method of manufacturing the pad, and a method of manufacturing a semiconductor device.SOLUTION: In the polishing pad having a polishing layer comprising a thermosetting polyurethane foam, the thermosetting polyurethane foam which contains an isocyanurate bond obtained by reacting an active hydrogen-containing compound with an isocyanate component in the presence of an isocyanurate catalyst while the number of isocyanate groups in the isocyanate component (NCO INDEX) for the total number of groups of active hydrogen in the active hydrogen-containing compound is set to 1.3-4.0 is used as the thermosetting polyurethane foam.

Description

  The present invention stabilizes flattening processing of optical materials such as lenses and reflection 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, a method for manufacturing the same, and a method for manufacturing a semiconductor device. The polishing pad of the present invention is particularly useful for finish polishing of a silicon wafer or glass.

  In general, mirror polishing of semiconductor wafers such as silicon wafers, lenses, and glass substrates mainly involves rough polishing mainly for adjusting the flatness and in-plane uniformity, and improving surface roughness and removing scratches. There is intended finish polishing.

  In finish polishing, a suede-like artificial leather made of soft polyurethane foam is usually applied to a rotatable surface plate, and a wafer containing colloidal silica is supplied to an alkali-based aqueous solution. This is done by rubbing (Patent Document 1).

  However, when the flatness of the polishing layer made of polyurethane foam used for finish polishing is low, there arises a problem that micro undulation occurs on the surface of the object to be polished. This micro waviness is particularly regarded as a problem in the recent field of finish polishing, and a polishing pad capable of further reducing the micro waviness is strongly demanded in the market.

  By the way, normally, when a large number of semiconductor wafers are planarized using a polishing pad, the fine irregularities on the surface of the polishing pad wear out, and the ability to supply abrasive (slurry) to the processed surface of the semiconductor wafer is reduced. Or the flattening speed of the wafer processing surface decreases, or the flattening characteristics deteriorate. For this reason, it is necessary to update and roughen (dress) the surface of the polishing pad using a dresser after the planarization of a predetermined number of semiconductor wafers. When dressing is performed for a predetermined time, innumerable fine irregularities are formed on the surface of the polishing pad, and the pad surface becomes fuzzy.

  The following Patent Document 2 describes a polishing cloth in which an isocyanurated urethane resin is adhered to a nonwoven fabric. However, such a nonwoven fabric type has a thin usable polishing layer and a short pad life. There was a problem.

JP 2003-37089 A JP 2007-31883 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polishing pad capable of preventing a decrease in dress speed and reducing microwaviness generated on the surface of an object to be polished, and a method for manufacturing the same. Another object is to provide a method for manufacturing a semiconductor device.

  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 shown below, and have completed the present invention.

  That is, the polishing pad according to the present invention is a polishing pad having a polishing layer made of a thermosetting polyurethane foam, wherein the thermosetting polyurethane foam contains an active hydrogen-containing compound and an isocyanate in the presence of an isocyanuration catalyst. The number of isocyanate groups (NCO INDEX) of the isocyanate component relative to the total number of active hydrogen groups of the active hydrogen-containing compound is 1.3 to 4.0. It is characterized by that.

  In general, as a method of increasing the dressing speed of the polishing pad, there is a method of increasing the amount of the crosslinking material having 3 or more functional groups in the polyurethane raw material. However, in this case, waviness on the surface of the polishing pad occurs during dressing, and as a result, fine waviness may occur on the surface of the object to be polished. On the other hand, in the present invention, the thermosetting polyurethane foam constituting the polishing layer has an active hydrogen-containing compound and an isocyanate in the presence of an isocyanurate-forming catalyst in a state where NCO INDEX is set to 1.3 to 4.0. Since the isocyanurate bond formed by the reaction with the component is contained, the undulation of the surface of the polishing pad can be suppressed while increasing the hardness of the thermosetting polyurethane foam. As a result, with the polishing pad according to the present invention, the dressing speed can be increased while reducing the fine waviness on the surface of the object to be polished.

  The polishing pad preferably has a Asker C hardness of 50 to 90. According to such a configuration, since the hardness of the thermosetting polyurethane foam constituting the polishing layer is sufficiently ensured, the micro undulation generated on the surface of the object to be polished while preventing the dressing speed of the polishing pad from being lowered. Can be further reduced.

  In the polishing pad, the isocyanuration catalyst is preferably an amine catalyst, and (N, N ′, N ″ -tris (3-dimethylaminopropyl) -sym hexahydrotriazine and 1,8-diazabicyclo It is more preferable that it is at least one of [5,4,0] -7-undecene phenol salt, and the reaction with an active hydrogen-containing compound and an isocyanate component in the presence of such an isocyanurate-forming catalyst, The isocyanurate bond can be more reliably formed in the curable polyurethane foam, and as a result, the dressing speed of the polishing pad can be more reliably prevented and the fine waviness of the polishing object can be further reduced. Become.

  In the polishing pad, the isocyanate component preferably contains an aromatic diisocyanate, and more preferably at least one of toluene diisocyanate, diphenylmethane diisocyanate, and carbodiimide-modified diphenylmethane diisocyanate. When the active hydrogen-containing compound and the isocyanate component are used in combination, the adhesion between the polishing layer and the base material layer is remarkably improved when the base material layer is laminated on the polishing layer.

  In the polishing pad, it is preferable that the thermosetting polyurethane foam has substantially spherical cells having an average cell diameter of 20 to 300 μm. The durability of the polishing layer can be improved by forming the polishing layer with a thermosetting polyurethane foam having substantially spherical cells with an average cell diameter of 20 to 300 μm. Therefore, when the polishing pad of the present invention is used, the planarization characteristic can be kept high for a long time, and the stability of the polishing rate is also improved. Here, the substantially spherical shape means a spherical shape and an elliptical shape. Oval and spherical bubbles are those having a major axis L to minor axis S ratio (L / S) of 5 or less, preferably 3 or less, more preferably 1.5 or less.

  The present invention also includes an active hydrogen-containing compound, an isocyanate component, and an isocyanurate-forming catalyst as raw material components, and the number of isocyanate groups in the isocyanate component (NCO INDEX) relative to the total number of active hydrogen groups in the active hydrogen-containing compound. A step of preparing a cell-dispersed urethane composition having a ratio of 1.3 to 4.0 by a mechanical foaming method, a step of applying the cell-dispersed urethane composition on a face material, and curing the cell-dispersed urethane composition A step of forming a polishing layer made of a thermosetting polyurethane foam having substantially spherical bubbles having an average bubble diameter of 20 to 300 μm and containing an isocyanurate bond, and the thickness of the polishing layer is adjusted uniformly. The present invention relates to a method of manufacturing a polishing pad including steps. According to this manufacturing method, it is possible to manufacture a polishing pad in which a decrease in dressing speed is prevented and micro waviness generated on the surface of the object to be polished is reduced.

  Furthermore, this invention relates to the manufacturing method of a semiconductor device including the process of grind | polishing the surface of a semiconductor wafer using the polishing pad in any one of the said.

Schematic configuration diagram showing an example of a polishing apparatus used in a semiconductor device manufacturing method

  The polishing pad of the present invention has a polishing layer made of a thermosetting polyurethane foam (hereinafter also referred to as “polyurethane foam”).

  Polyurethane resin is excellent in abrasion resistance, and it is possible to easily obtain polymers having desired physical properties by changing the raw material composition. Also, it is easy to form almost spherical fine bubbles by mechanical foaming (including mechanical flossing). Since it can be formed, it is a particularly preferable material as a constituent material of the polishing layer.

  The polyurethane resin mainly contains an isocyanate component and an active hydrogen-containing compound (high molecular weight polyol, low molecular weight polyol, low molecular weight polyamine, chain extender, etc.).

  As the isocyanate component, a known compound in the field of polyurethane can be used without particular limitation. For example, 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, commercial products) 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, 2,2 Aliphatic diisocyanates such as 1,4-trimethylhexamethylene diisocyanate and 1,6-hexamethylene diisocyanate Hexane diisocyanate, cyclohexane diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, isophorone diisocyanate, alicyclic diisocyanates such as norbornane diisocyanate. These may be used alone or in combination of two or more.

  Of the above isocyanate components, aromatic diisocyanates are preferably used, and at least one of toluene diisocyanate, diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate is particularly preferably used.

  Examples of the active hydrogen-containing compound include those usually used in the technical field of polyurethane, such as a high molecular weight polyol, a low molecular weight polyol, a low molecular weight polyamine, and a chain extender.

  Examples of the high molecular weight polyol include polyether polyols represented by polytetramethylene ether glycol and polyethylene glycol, polyester polyols represented by polybutylene adipate, polyester glycols such as polycaprolactone polyol and polycaprolactone, and alkylene carbonates. Polyester polycarbonate polyol, which is exemplified by the reaction product of 1. Polyester polycarbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol, and then reacting the obtained reaction mixture with organic dicarboxylic acid, transesterification of polyhydroxyl compound with aryl carbonate Polycarbonate polyol obtained by the reaction, poly which is a polyether polyol in which polymer particles are dispersed Such as over polyols. These may be used alone or in combination of two or more.

  Examples of the low molecular weight polyol include trimethylolpropane, glycerin, diglycerin, 1,2,6-hexanetriol, triethanolamine, pentaerythritol, tetramethylolcyclohexane, methyl glucoside, and alkylene oxides thereof (EO, PO, etc.) ) Additives. These may be used alone or in combination of two or more.

  Examples of the low molecular weight polyamine include ethylenediamine, tolylenediamine, diphenylmethanediamine, and alkylene oxide (EO, PO, etc.) adducts thereof. These may be used alone or in combination of two or more.

  Further, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6 -Low molecular weight polyols such as hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol and triethylene glycol may be used in combination. Further, alcohol amines such as monoethanolamine, diethanolamine, 2- (2-aminoethylamino) ethanol, and monopropanolamine may be used in combination.

  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 Polyamines exemplified by diamine, N, N′-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and p-xylylenediamine, or the low molecular weight polyols and low molecular weight polyamines described above. Can be mentioned. These may be used alone or in combination of two or more.

  In the present invention, the content of the trifunctional polyol having a hydroxyl value of 200 to 1500 mgKOH / g is preferably 40 parts by weight or less in 100 parts by weight of the active hydrogen-containing compound. When the content of the trifunctional polyol exceeds 40 parts by weight, scratches tend to occur on the surface of the object to be polished. Moreover, it is preferable to make content of the low molecular weight polyol whose hydroxyl value is 900-1830 mgKOH / g into 20 weight part or less in 100 weight part of active hydrogen containing compounds. When the content of the low molecular weight polyol exceeds 20 parts by weight, there is a tendency that scratches are easily generated on the surface of the object to be polished.

  The thermosetting polyurethane foam according to the present invention is formed by the reaction of an active hydrogen-containing compound and an isocyanate component in the presence of an isocyanuration catalyst in a state where NCO INDEX is set to 1.3 to 4.0. Contains isocyanurate linkages.

  Examples of the isocyanuration catalyst include (N, N ′, N ″ -tris (3-dimethylaminopropyl) -symhexahydrotriazine, 1,8-diazabicyclo [5,4,0] -7-undecene (DBU). ) And amine catalysts such as DBU phenol salts, and C1-C20 organic carboxylic acid alkali metal salts such as potassium 2-ethylhexanoate (octylate), potassium acetate, and potassium propionate, among these. Amine-based catalysts are preferred and include (N, N ′, N ″ -tris (3-dimethylaminopropyl) -sym hexahydrotriazine and 1,8-diazabicyclo [5,4,0] -7-undecene phenol salt. More preferably, the compounding amount of the isocyanurate catalyst is an active hydrogen-containing compound. When the total amount of is 100 parts by weight, it is preferably 0.03 to 0.15 parts by weight.If the amount of the isocyanurate catalyst is less than 0.03 parts by weight, the reaction for forming an isocyanurate bond proceeds. When the amount exceeds 0.15 parts by weight, the formability of the polyurethane foam tends to deteriorate.

  The thermosetting polyurethane foam can be manufactured by applying a known urethanization technique such as a melting method or a solution method, but is preferably manufactured by a melting method in consideration of cost, working environment, and the like. In addition, the thermosetting polyurethane foam can be produced by either the prepolymer method or the one-shot method, but with the NCO INDEX set to 1.3 to 4.0, in the presence of an isocyanuration catalyst, It is preferable that the active hydrogen-containing compound and the isocyanate component be reacted and cured by a one-shot method in which the active hydrogen-containing compound is directly reacted. When a thermosetting polyurethane foam is formed by the one-shot method, the isocyanate component becomes high in concentration, so that an isocyanurate bond can be formed more reliably, preventing a decrease in dress speed and occurring on the surface of the object to be polished. The reduction of micro swell can be achieved more reliably, which is preferable.

  The thermosetting polyurethane foam, which is a constituent material of the polishing layer, can be produced by a mechanical foaming method (including a mechanical floss method). In particular, a mechanical foaming method using a silicon surfactant which is a copolymer of polyalkylsiloxane and polyether is preferable. Examples of suitable silicon surfactants include SH-192 and L-5340 (manufactured by Toray Dow Corning Silicone), B8443 (manufactured by Goldschmidt), and the like.

  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 thermosetting polyurethane foam constituting the polishing layer will be described below. The manufacturing method of this polyurethane foam has the following processes.

  (1) A silicon-based surfactant is added to at least one of the first component containing an isocyanate component and the second component containing an active hydrogen-containing compound, and the component to which the silicon-based surfactant is added is present as a non-reactive gas. Under mechanical stirring, the non-reactive gas is dispersed 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.

  (2) A silicon-based surfactant is added to at least one of the first component containing the isocyanate component and the second component containing the active hydrogen-containing compound, and the first component and the second component are added in the presence of a non-reactive gas. Then, a non-reactive gas is dispersed as fine bubbles to prepare a cell-dispersed urethane composition.

  The cell dispersed urethane composition may be prepared by a mechanical floss method. Mechanical flossing means that raw material components are put into the mixing chamber of the mixing head and non-reactive gas is mixed, and mixed and stirred with a mixer such as 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 substantially spherical fine cell with an average cell diameter of 20-300 micrometers can be continuously shape | molded, manufacturing efficiency is good.

  Thereafter, the cell-dispersed urethane composition prepared by the above method is applied onto a face material, and the cell-dispersed urethane composition is cured to form a thermosetting polyurethane foam (polishing layer) directly on the face material. .

  The non-reactive gas used for forming the fine bubbles is preferably non-flammable, and specific examples include nitrogen, oxygen, carbon dioxide gas, rare gases such as helium and argon, and mixed gases thereof. The use of air that has been dried to remove moisture is most preferable in terms of cost.

  As a stirring device for dispersing the non-reactive gas in the form of fine bubbles, a known stirring device can be used without any particular limitation. Specifically, a homogenizer, a dissolver, a two-axis planetary mixer (planetary mixer), a mechanical A floss foaming machine etc. are illustrated. 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 that the stirring for preparing the cell dispersion in the foaming step and the stirring for mixing the first component and the second component use different stirring devices. The agitation in the mixing step may not be agitation that forms bubbles, and it is preferable to use an agitation 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 for preparing the bubble dispersion and the mixing step for mixing each component, and the stirring conditions such as adjusting the rotation speed of the stirring blades are adjusted as necessary. It is also suitable to use after adjustment.

  In the polishing pad according to the present invention, a base material layer may be laminated on the polishing layer. The base material layer is not particularly limited when the base material layer is laminated on the polishing layer. For example, plastic films such as nylon, polypropylene, polyethylene, polyester, and polyvinyl chloride, and polymer resin foams such as polyurethane foam and polyethylene foam Bodies, rubber resins such as butadiene rubber and isoprene rubber, and photosensitive resins. Among these, it is preferable to use polymer resin foams such as plastic films such as nylon, polypropylene, polyethylene, polyester, and polyvinyl chloride, polyurethane foam, and polyethylene foam. Moreover, you may use a double-sided tape and a single-sided adhesive tape (a single-sided adhesive layer is for affixing on a platen) as a base material layer.

  The base material layer is preferably as hard as a polyurethane foam or harder in order to impart toughness to the polishing pad. The thickness of the base material layer (the base material in the case of double-sided tape and single-sided adhesive tape) is not particularly limited, but is preferably 20 to 1000 μm, more preferably 50 to 1000 from the viewpoint of strength, flexibility and the like. 800 μm.

  As a method for applying the cell-dispersed urethane composition onto the face material, for example, a roll coater such as gravure, kiss, or comma, a die coater such as slot or phanten, a squeeze coater, or a curtain coater may be employed. However, any method may be used as long as a uniform coating film can be formed on the face material.

  Heating and post-curing the polyurethane foam that has reacted until the cell-dispersed urethane composition is applied to the face material until it no longer flows has the effect of improving the physical properties of the polyurethane foam and is extremely suitable. . Post-cure is preferably performed at 40 to 70 ° C. for 10 minutes to 24 hours, and it is preferable to perform at normal pressure because the bubble shape is stable.

  The polyurethane foam may be produced by a batch method in which each component is weighed and put into a container and mechanically stirred, and each component and a non-reactive gas are continuously supplied to a stirring device and mechanically stirred. Further, a continuous production method in which a cell-dispersed urethane composition is sent out to produce a molded product may be used.

  In the manufacturing method of the polishing pad of the present invention, it is necessary to uniformly adjust the thickness of the polyurethane foam after forming the polyurethane foam on the face material or simultaneously with forming the polyurethane foam. The method for uniformly adjusting the thickness of the polyurethane foam is not particularly limited, and examples thereof include a method of buffing with an abrasive and a method of pressing with a press plate. When buffing, a polishing layer having no skin layer on the surface of the polyurethane foam is obtained, and when pressed, a polishing layer having a skin layer on the surface of the polyurethane foam is obtained. The conditions for pressing are not particularly limited, but it is preferable to adjust the temperature above the glass transition point.

  On the other hand, the cell-dispersed urethane composition prepared by the above method is applied onto a release sheet, and a base material layer is laminated on the cell-dispersed urethane composition. Thereafter, the polyurethane foam may be formed by curing the cell-dispersed urethane composition while making the thickness uniform by a pressing means. This method is particularly preferable because the thickness of the polishing layer can be controlled very uniformly.

  The constituent material of the release sheet is not particularly limited, and examples thereof include the same resin and paper as the base material layer. The release sheet preferably has a small dimensional change due to heat. The surface of the release sheet may be subjected to a release treatment.

  The pressing means for making the thickness of the sandwich sheet composed of the release sheet, the cell-dispersed urethane composition (cell-dispersed urethane layer), and the base material layer is not particularly limited. For example, the thickness may be constant by a coater roll, a nip roll, or the like. The method of compressing is mentioned. In consideration of the fact that the bubbles in the foamed layer become about 1.2 to 2 times larger after the compression, the (coater or nip clearance)-(base layer and release sheet thickness) = (after curing) The thickness of the polyurethane foam is preferably 50 to 85%.

  Then, after the thickness of the sandwich sheet is made uniform, the reacted polyurethane foam is heated and post-cured until it does not flow. Post cure conditions are the same as described above.

  Thereafter, the release sheet under the polyurethane foam is peeled off. In this case, a skin layer is formed on the polyurethane foam. When the polyurethane foam is formed by the mechanical foaming method as described above, the variation in bubbles is smaller on the lower surface side than on the upper surface side of the polyurethane foam. Thus, since the lower surface side of the formed polyurethane foam is used as the polishing surface, the polishing surface has a small variation in bubbles, and thus the stability of the polishing rate is further improved. The skin layer may be removed by buffing the polyurethane foam after peeling off the release sheet.

  The thickness of the polyurethane foam is not particularly limited, but is preferably 0.2 to 3 mm, and more preferably 0.5 to 2 mm.

  The polyurethane foam produced by the production method described above has substantially spherical cells. In addition, the polyurethane foam according to the present invention may have open cells or may have closed cells.

  The average cell diameter of the bubbles in the polyurethane foam is 20 to 300 μm, preferably 50 to 100 μm. In the case of open cells, the average diameter of the circular holes on the surface of the bubbles is preferably 100 μm or less, more preferably 50 μm or less.

  The specific gravity of the polyurethane foam is preferably 0.3 to 0.6, more preferably 0.3 to 0.5. When the specific gravity is less than 0.3, the bubble rate becomes too high and the durability tends to deteriorate. On the other hand, when the specific gravity exceeds 0.6, the material needs to have a low cross-linking density in order to obtain a certain elastic modulus. In that case, permanent set increases and durability tends to deteriorate.

  The polyurethane foam preferably has an Asker C hardness of 50 to 90 degrees, and more preferably 70 to 90 degrees. When Asker C hardness is less than 50 degrees, the dressing speed tends to be slow, and the durability tends to decrease, or the flatness of the polished object after polishing tends to be poor. On the other hand, when it exceeds 90 degrees, scratches are likely to occur on the surface of the object to be polished.

  The shape of the polishing pad of the present invention is not particularly limited, and may be a long shape having a length of about 5 to 10 m or a round shape having a diameter of about 50 to 150 cm.

  The surface of the polishing layer may have a concavo-convex structure for holding and renewing 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 polishing object due to adsorption with the polishing object 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 the groove pitch, groove width, groove depth, etc. can be changed for each range in order to make the slurry retention and renewability desirable. 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 resin is poured into a mold having a predetermined surface shape, and cured. Manufacturing method, pressing and manufacturing a resin with a press plate having a predetermined surface shape, manufacturing method using photolithography, manufacturing method using a printing technique, laser using a carbon dioxide laser, etc. Examples thereof include a light production method.

  The polishing pad of the present invention may have a cushion sheet bonded to the non-polishing surface side of the polishing layer. When laminating a substrate layer on the polishing layer, it is preferable to laminate the polishing layer, the substrate layer, and the cushion sheet in this order.

  The cushion sheet (cushion layer) supplements the characteristics of the polishing layer. The cushion sheet is necessary to achieve both planarity and uniformity in a trade-off relationship in chemical mechanical polishing. Planarity refers to the flatness of a pattern portion when a polishing object having minute irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire polishing object. The planarity is improved by the characteristics of the polishing layer, and the uniformity is improved by the characteristics of the cushion sheet. In the polishing pad of the present invention, it is preferable to use a cushion sheet that is softer than the polishing layer.

  Examples of the cushion sheet 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, butadiene rubber, and isoprene. Examples thereof include rubber resins such as rubber and photosensitive resins.

  Examples of means for attaching the cushion sheet include a method in which a polishing layer and a cushion sheet are sandwiched and pressed with a double-sided tape.

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

  A semiconductor device is manufactured through a process of polishing the surface of a 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. A semiconductor device is used for an arithmetic processing unit, 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 of specific gravity)
This was performed according to JIS Z8807-1976. The produced polyurethane foam was cut into a 4 cm × 8.5 cm strip (thickness: arbitrary) as a sample and allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. The specific gravity was measured using a hydrometer (manufactured by Sartorius).

(Measurement of hardness)
This was performed according to JIS K-7312. The produced polyurethane foam was cut into a size of 5 cm × 5 cm (thickness: arbitrary) as a sample and 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 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 30 seconds after contacting the pressure surface was measured.

(Dressing speed measurement)
The surface of the prepared polishing layer was uniformly dressed while being rotated using four diamond dressers (# 400 specification, 24 diamond pellets manufactured by Speedfam). The dresser load at this time was 100 g / cm ² , the lower surface plate rotation speed was 50 rpm, and the dressing time was 20 minutes. Then, the dressing speed was calculated from the thickness of the polishing layer before and after the dressing.

(Slight swell)
Using a non-contact surface profile measuring machine (NewView 6300 manufactured by ZYGO), setting the bandpass filter to 200 to 1250 μm with a lens magnification of 2.5 times and a zoom magnification of 0.5 times, and 5 points on the surface of the object to be polished Ra was measured, and the average value (nm) was defined as minute undulation. In measuring fine waviness, a polishing object polished by the following polishing method was used.

(Polishing method)
Setting conditions of the double-side polishing machine Double-side polishing machine; 9F type double-side polishing machine manufactured by Speedfam Corporation Processing pressure: 100 g / cm ²
Plate rotation speed: 50 rpm
Abrasive supply amount: 4 L / min
Input substrate: TS-10SX manufactured by OHARA
Number of substrates loaded: 25 sheets Continuous polishing was performed until the substrate thickness reached 85% of the initial thickness. In addition, the used abrasive | polishing agent was adjusted with the following method.

(Abrasive adjustment method)
SHOROX A-10 (manufactured by Showa Denko KK) was added to water and mixed to adjust the abrasive so as to have a specific gravity of 1.06 to 1.09.

(material)
Each raw material used is as follows.

(I) Active hydrogen-containing compound Polycaprolactone polyol “Placcel 210 (PCL210)”, number of functional groups: 2, hydroxyl value: 110 mgKOH / g, manufactured by Daicel Chemical Industries, Ltd. Polycaprolactone polyol “Placcel 305 (PCL305)”, number of functional groups: 3, Hydroxyl value: 305 mgKOH / g, manufactured by Daicel Chemical Industries, Ltd. Polytetramethylene ether glycol “PTMG1000”, number of functional groups: 2, hydroxyl value: 110 mgKOH / g, manufactured by Mitsubishi Chemical Corporation, polytetramethylene ether glycol “PTMG2000”, number of functional groups: 2, Hydroxyl value: 56 mg KOH / g, Mitsubishi Chemical Corporation diethylene glycol (DEG) Functional group number: 2, Hydroxyl value: 1057 mg KOH / g, Nacalai Tesque 1,4-butanediol (1,4-BD) Functional group number: 2, Sanmotoka: 1247mgKOH / g, a propylene oxide adduct of Nacalai Tesque trimethylolpropane "EXCENOL 890MP", number of functional groups: 3, hydroxyl value: 865mgKOH / g, manufactured by Asahi Glass Co., Ltd.

(Ii) Isocyanate component Carbodiimide-modified diphenylmethane diisocyanate (MDI), “Millionate MTL”, manufactured by Nippon Polyurethane Industry Co., Ltd.

(Iii) Catalyst N, N-dimethylaminohexanol “Kao No. 25”, N, N ′, N ″ -tris (3-dimethylaminopropyl) -sym hexahydrotriazine “Kao No. 14” manufactured by Kao Corporation, 1,8-diazabicyclo [5,4,0] -7-undecene phenol salt “U-CAT” manufactured by Kao Corporation, manufactured by San Apro

(Iv) Foam stabilizer “B8443”, manufactured by Goldschmidt

Examples 1-9 and Comparative Examples 1-5
The active hydrogen-containing compound, the isocyanurate-forming catalyst, and the foam stabilizer so as to have the blending ratios shown in the upper part of Table 1 and Table 2 (the numerical values are parts by weight when the total amount of the active hydrogen-containing compound is 100 parts by weight) The agent was placed in a container and stirred vigorously for about 4 minutes using a stirring blade so that bubbles were taken into the reaction system at a rotation speed of 900 rpm. Thereafter, carbodiimide-modified MDI was added so that the NCO INDEX was a value described in Tables 1 and 2, and stirred for about 1 minute to prepare a cell-dispersed urethane composition.

  The prepared cell-dispersed urethane composition was applied onto a release sheet composed of a release-treated PET sheet (Toyobo Co., Ltd., thickness: 75 μm) to form a cell-dispersed urethane layer. And the base material layer which consists of PET sheet | seat (Toyobo Co., Ltd. thickness 188 micrometers) was covered on this cell dispersion | distribution urethane layer. The cell-dispersed urethane layer was made 1.5 mm thick with a nip roll, subjected to primary curing at 40 ° C. for 30 minutes, and then secondary cured at 70 ° C. for 3 hours to form a polyurethane foam (foamed layer). This production method corresponds to the one-shot method because a polyurethane foam is produced by directly reacting an active hydrogen-containing compound with an isocyanate component in the presence of an isocyanurate-forming catalyst.

  Thereafter, the release sheet was peeled off. Next, the thickness of the polyurethane foam was adjusted to 1.3 mm using a slicer (manufactured by Fecken) to adjust the thickness accuracy. Thereafter, a double-sided tape (double tack tape, manufactured by Sekisui Chemical Co., Ltd.) was bonded to the surface of the base material layer using a laminator to prepare a polishing pad.

  From the results of Tables 1 and 2, the polishing pads of Examples 1 to 9 have a faster dressing speed than the polishing pads of Comparative Examples 1 to 5, and the microwaviness generated on the surface of the object to be polished is reduced. I understand that.

1: Polishing pad 2: Polishing surface plate 3: Abrasive (slurry)
4: Polishing target (semiconductor wafer, lens, glass plate)
5: Support base (polishing head)
6, 7: Rotating shaft

Claims (9)

In a polishing pad having a polishing layer made of a thermosetting polyurethane foam,
The thermosetting polyurethane foam contains an isocyanurate bond formed by a reaction between an active hydrogen-containing compound and an isocyanate component in the presence of an isocyanurate-forming catalyst, and the total of the active hydrogen-containing compounds A polishing pad, wherein the number of isocyanate groups (NCO INDEX) of the isocyanate component relative to the number of active hydrogen groups is 1.3 to 4.0.   The polishing pad according to claim 1, wherein the hardness in terms of Asker C hardness is 50 to 90.   The polishing pad according to claim 1, wherein the isocyanurate-forming catalyst is an amine-based catalyst.   The isocyanurate-forming catalyst comprises (N, N ′, N ″ -tris (3-dimethylaminopropyl) -sym hexahydrotriazine and 1,8-diazabicyclo [5,4,0] -7-undecene phenol salt. The polishing pad according to claim 1, which is at least one of the following.   The polishing pad according to claim 1, wherein the isocyanate component contains an aromatic diisocyanate.   The polishing pad according to claim 1, wherein the isocyanate component is at least one of toluene diisocyanate, diphenylmethane diisocyanate, and carbodiimide-modified diphenylmethane diisocyanate.   The polishing pad according to any one of claims 1 to 6, wherein the thermosetting polyurethane foam has substantially spherical cells having an average cell diameter of 20 to 300 µm.   An active hydrogen-containing compound, an isocyanate component, and an isocyanurate-forming catalyst are contained as raw material components, and the isocyanate group number (NCO INDEX) of the isocyanate component relative to the total active hydrogen group number of the active hydrogen-containing compound is 1.3 to 4. 0.0, a step of preparing a cell-dispersed urethane composition by a mechanical foaming method, a step of applying the cell-dispersed urethane composition on a face material, and curing the cell-dispersed urethane composition, an average cell diameter of 20 to 20 A polishing pad comprising a step of forming a polishing layer made of a thermosetting polyurethane foam having a substantially spherical bubble of 300 μm and containing an isocyanurate bond, and a step of uniformly adjusting the thickness of the polishing layer Production method.   A method for manufacturing a semiconductor device, comprising a step of polishing a surface of a semiconductor wafer using the polishing pad according to claim 1.

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