JP4941735B2 - Polishing pad manufacturing method - 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, In addition, the present invention relates to a polishing pad that can be performed with high polishing efficiency. The polishing pad of the present invention is particularly suitable for a step of planarizing a silicon wafer and a device having an oxide layer, a metal layer, etc. formed thereon, before further laminating and forming these oxide layers and metal layers. Used for.

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

  As a polishing pad used for such a polishing operation, for example, the following has been proposed. First, a polyurethane foam in which polymer foam microelements are dispersed, or a polyurethane foam obtained by stirring an isocyanate prepolymer in the presence of a surfactant to prepare a cell dispersion and adding a chain extender thereto. Is manufactured in a block shape. Then, a polishing pad manufactured by slicing the block-like polyurethane foam to obtain an abrasive sheet and cutting it into a circle has been proposed (Patent Documents 1 and 2).

  A linear belt-like (web-like) polishing pad has also been proposed (Patent Documents 3 and 4). Conventionally, such a belt-like polishing pad is obtained by slicing a block-like foam as described above to obtain an abrasive sheet, and affixing a plurality of sheets onto another belt-like material (such as a stainless steel belt). It was manufactured by. However, since the conventional belt-shaped polishing pad is a laminate of a plurality of polishing sheets, peeling occurs at the end of the sheet, or the workpiece is easily caught at the end of the sheet, and smooth polishing cannot be performed. Had a problem.

  As a method for solving the above problem, a method of tapering or rounding the upper end portion of the polishing pad, or a method of engaging unevenness respectively provided at the end portions of adjacent polishing pads has been proposed (Patent Document 5). . However, even if problems such as peeling can be improved to some extent by using the polishing pad, it cannot be completely solved.

  Further, when performing CMP, there is a problem of determining the flatness of the wafer surface. In other words, it is necessary to detect when the desired surface characteristics or planar state is reached. Conventionally, with regard to the thickness of the oxide film, the polishing rate, and the like, a test wafer is periodically processed, and after confirming the result, a product wafer is polished.

  However, in this method, the time and cost for processing the test wafer are wasted, and the polishing result differs between the test wafer and the product wafer that have not been processed in advance due to the loading effect peculiar to CMP. If it is not actually processed, it is difficult to accurately predict the processing result.

  Therefore, recently, in order to solve the above-mentioned problems, there is a demand for a method capable of detecting a point in time when desired surface characteristics and thickness are obtained in the CMP process. Various methods are used for such detection. From the viewpoint of measurement accuracy and spatial resolution in non-contact measurement, an optical detection method in which a film thickness monitoring mechanism using a laser beam is incorporated in a rotating surface plate ( Patent Documents 6 and 7) are becoming mainstream.

  Specifically, the optical detection means detects a polishing end point by irradiating a wafer with a light beam through a window (light transmission region) through a polishing pad and monitoring an interference signal generated by the reflection. Is the method.

  Currently, white light using a He—Ne laser light having a wavelength near 600 nm or a halogen lamp having a wavelength light in the range of 380 to 800 nm is generally used as the light beam.

  In such a method, the end point is determined by monitoring the change in the thickness of the surface layer of the wafer and knowing the approximate depth of the surface irregularities. When such a change in thickness becomes equal to the depth of the unevenness, the CMP process is terminated. Various methods have been proposed for the polishing end point detection method using such optical means and the polishing pad used in the method.

  For example, a polishing pad having at least a part of a transparent polymer sheet that transmits solid and homogeneous light having a wavelength of 190 nm to 3500 nm is disclosed (Patent Document 8). Further, a polishing pad in which a stepped transparent plug is inserted is disclosed (Patent Document 9). In addition, a polishing pad having a transparent plug that is flush with the polishing surface is disclosed (Patent Document 10).

  On the other hand, proposals (Patent Documents 11 and 12) for preventing the slurry from leaking from the boundary (seam) between the polishing region and the light transmission region have also been made. However, even when these transparent leakage prevention sheets are provided, the slurry leaks from the boundary (seam) between the polishing region and the light transmission region to the lower part of the polishing layer, and the slurry accumulates on the leakage prevention sheet to cause an optical end point. Problems with detection.

  In the future, with high integration and ultra-miniaturization in semiconductor manufacturing, it is expected that the wiring width of integrated circuits will become smaller, and in that case, highly accurate optical end point detection will be required. The end point detection window cannot sufficiently solve the problem of slurry leakage.

Japanese Patent No. 3455517 Japanese Patent No. 3516874 JP 2001-156031 A JP 2005-510368 gazette Japanese Patent Laid-Open No. 2005-19669 US Pat. No. 5,069,002 US Pat. No. 5,081,421 Japanese National Patent Publication No. 11-512977 Japanese Patent Laid-Open No. 9-7985 Japanese Patent Laid-Open No. 10-83977 JP 2001-291686 A Japanese translation of PCT publication No. 2003-510826

  It is an object of the present invention to provide a method for producing a continuous long polishing pad. It is another object of the present invention to provide a method for manufacturing a polishing pad that can prevent slurry leakage between the polishing region and the light transmission region with high productivity.

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

  That is, the present invention provides a process for producing a cylindrical resin block in which a cylindrical polishing region and a cylindrical light transmission region are stacked, or a columnar resin block in which a columnar polishing region and a columnar light transmission region are stacked. The present invention also relates to a polishing pad manufacturing method including a step of slicing a surface portion of a resin block with a predetermined thickness while rotating about the axis of the resin block to produce a belt-shaped resin sheet.

  The cylindrical resin block preferably has a three-layer structure in which a first cylindrical polishing region, a cylindrical light transmission region, and a second cylindrical polishing region are laminated in this order. It is preferable to have a three-layer structure in which the first cylindrical polishing region, the cylindrical light transmission region, and the second cylindrical polishing region are laminated in this order.

  The polishing region is preferably made of polyurethane foam, and the light transmission region is preferably made of polyurethane non-foamed material.

  The resin block preferably has a diameter of 10 cm or more. When the block diameter is less than 10 cm, the strip-shaped resin sheet obtained by slicing is likely to be rounded or undulated. As a result, there is a tendency that floating occurs when the polishing pad is bonded to another belt-shaped material or the polishing characteristics are deteriorated.

  Moreover, it is preferable that the said strip | belt-shaped resin sheet is 0.1-3 mm in thickness. When the thickness is less than 0.1 mm, the rigidity is lowered and the flattening characteristics are deteriorated. On the other hand, when the thickness is more than 3 mm, the film tends to be rounded or undulated.

  Moreover, the length of the belt-shaped resin sheet is preferably 5 m or more from the viewpoints of polishing efficiency and production efficiency of a workpiece.

  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 obtained by the said manufacturing method.

  The method for producing a polishing pad of the present invention includes a cylindrical resin block in which a cylindrical polishing region and a cylindrical light transmission region are stacked, or a columnar resin block in which a columnar polishing region and a columnar light transmission region are stacked. And a step of slicing the surface portion of the resin block with a predetermined thickness while rotating around the axis of the resin block to produce a belt-shaped resin sheet.

  The material for forming the polishing region is not particularly limited. For example, polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, Examples thereof include one or a mixture of two or more of olefinic resins (polyethylene, polypropylene, etc.), epoxy resins, and photosensitive resins. Polyurethane resin is particularly preferable as a material for forming a polishing region 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, the case where a polyurethane resin (thermosetting polyurethane resin) is used as a representative forming material will be described.

  The polyurethane resin comprises an isocyanate component, a polyol component (high molecular weight polyol, low molecular weight polyol, etc.), 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.

  As the isocyanate component, a trifunctional or higher polyfunctional polyisocyanate compound can be used in addition to the diisocyanate compound. As a polyfunctional isocyanate compound, a series of diisocyanate adduct compounds are commercially available as Desmodur-N (manufactured by Bayer) or trade name Duranate (manufactured by Asahi Kasei Kogyo Co., Ltd.).

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

  The number average molecular weight of the high molecular weight polyol is not particularly limited, but is preferably 500 to 2000 from the viewpoint of the elastic properties of the resulting polyurethane resin. When the number average molecular weight is less than 500, a polyurethane resin using the number average molecular weight does not have sufficient elastic properties and becomes a brittle polymer. For this reason, the polishing region manufactured from this polyurethane resin becomes too hard, which causes scratches on the wafer surface. Moreover, since it becomes easy to wear, it is not preferable from the viewpoint of the pad life. On the other hand, when the number average molecular weight exceeds 2000, a polyurethane resin using the number average molecular weight becomes too soft, and a polishing region produced from the polyurethane resin tends to be inferior in flattening characteristics.

  In addition to the above-described high molecular weight polyol as a polyol component, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4 -It is preferable to use a low molecular weight polyol such as cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene or the like. Low molecular weight polyamines such as ethylenediamine, tolylenediamine, diphenylmethanediamine and diethylenetriamine may be used.

  When the polyurethane resin is produced by the 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, the desired physical properties of the polishing pad, and the like. In order to obtain a polishing region 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 resin can be produced by either the prepolymer method or the one-shot method, but a prepolymer method in which an isocyanate-terminated prepolymer is synthesized in advance from an isocyanate component and a polyol component and then reacted with a chain extender. However, the obtained polyurethane resin has excellent physical properties and is suitable.

  On the other hand, the material for forming the light transmission region is not particularly limited, but it is possible to detect the optical end point with high accuracy in the state of polishing, and the material has a light transmittance of 20% or more over the entire wavelength range of 400 to 700 nm. It is preferable to use a material having a light transmittance of 50% or more. Examples of such materials include polyurethane resins, polyester resins, phenol resins, urea resins, melamine resins, epoxy resins, and acrylic resins, and other thermosetting resins, polyurethane resins, polyester resins, polyamide resins, cellulose resins, Thermoplastic resins such as acrylic resins, polycarbonate resins, halogen resins (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, and olefin resins (polyethylene, polypropylene, etc.), light such as ultraviolet rays and electron beams And a photo-curable resin that is cured by the above-described method and a photosensitive resin. These resins may be used alone or in combination of two or more. In particular, a highly abrasion-resistant polyurethane resin that can suppress light scattering in the light transmission region due to dressing marks during polishing is desirable.

  Hereinafter, a method for manufacturing a cylindrical resin block in which a cylindrical polishing region and a cylindrical light transmission region are stacked, or a columnar resin block in which a columnar polishing region and a columnar light transmission region are stacked will be described.

  The cylindrical resin block may have a two-layer structure in which a cylindrical polishing region and a cylindrical light transmission region are stacked one by one, or a multilayer structure in which a cylindrical polishing region and a cylindrical light transmission region are sequentially stacked. It may be. The same applies to the cylindrical resin block.

  In the present invention, the cylindrical resin block preferably has a three-layer structure in which a first cylindrical polishing region, a cylindrical light transmission region, and a second cylindrical polishing region are laminated in this order. The columnar resin block preferably has a three-layer structure in which a first cylindrical polishing region, a cylindrical light transmission region, and a second cylindrical polishing region are laminated in this order.

  As a manufacturing method of a cylindrical resin block having a three-layer structure, for example, (1) the polyurethane resin composition A is injected into a column mold and cured to form a first columnar polishing region, and then the first circle The polyurethane resin composition B is injected and cured on the columnar polishing region to form a cylindrical light transmission region, and then the polyurethane resin composition A is again injected and cured on the cylindrical light transmission region. Two cylindrical polishing regions are formed to produce a cylindrical resin block. And, a method of producing a cylindrical resin block by providing a through-hole in the center of the cylindrical resin block, (2) a method of producing a cylindrical resin block by the same method as described above using a cylindrical mold, (3) A cylindrical light transmission region is set in a cylindrical mold, and a polyurethane resin composition is injected and cured on both sides of the cylindrical light transmission region to form first and second cylindrical polishing regions to form a cylindrical shape. A resin block is produced. And a method of producing a cylindrical resin block by providing a through hole in the center of the columnar resin block, and (4) a first cylindrical polishing region, a cylindrical light transmission region, and a second cylindrical shape by molding. Examples include a method of producing a cylindrical resin block by producing each polishing region and bonding these members together using an adhesive or a double-sided tape.

  The columnar resin block having a three-layer structure can be produced by the same method as described above except that no through hole is provided. In addition, a cylindrical resin block and a columnar resin block having a two-layer structure or a multilayer structure can also be produced by applying the method.

  In the case of a resin block having a three-layer structure, the cylindrical light transmission region or the columnar light transmission region may be disposed at the center in the width direction of the resin block or at the end in the width direction, and has a relationship with the polishing apparatus to be used. Adjust the position as appropriate.

  The polishing region is preferably a polyurethane foam, and the light transmission region is preferably a polyurethane non-foam.

  Examples of the method for producing the polyurethane foam include a method of adding hollow beads, a mechanical foaming method, a chemical foaming method, and the like. In particular, a mechanical foaming method using a silicone surfactant which is a copolymer of polyalkylsiloxane and polyether and does not have an active hydrogen group is preferable. As such a silicon-based surfactant, SH-192, L-5340 (manufactured by Toray Dow Corning Silicone) and the like are exemplified as suitable compounds.

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

An example of a method for producing a fine bubble type cylindrical or columnar polishing region will be described below. The manufacturing method of this grinding | polishing area | region has the following processes.
1) Foaming process for producing an isocyanate-terminated prepolymer cell dispersion Add a silicon-based surfactant to the isocyanate-terminated prepolymer and mechanically stir it in the presence of a non-reactive gas to disperse the non-reactive gas as fine bubbles. To make a bubble 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 is added to the above-mentioned cell dispersion and mixed with stirring to obtain a foaming reaction solution.
3) Casting process The above foaming reaction liquid is poured into a mold.
4) Curing step The foamed reaction solution that has been poured 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.

  As a stirring device for dispersing non-reactive gas in the form of fine bubbles and dispersing in a composition containing a silicon-based surfactant, a known stirring device can be used without particular limitation. 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 are easily formed.

  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 very suitable because it has the effect of improving the physical properties of the foam. is there. The foaming reaction solution may be poured into the mold and heated in the mold to completely cure the foam, or the foam is taken out of the mold at the stage where the fluidity is lost, and then placed in a heating oven. It may be put and cured completely. The curing reaction is preferably performed at normal pressure because the bubble shape is stable.

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

  The diameter of the cylindrical or columnar resin block produced by such a method is preferably 10 cm or more, more preferably 30 cm or more. The width of the resin block is preferably 30 cm or more, more preferably 50 cm or more, and particularly preferably 100 cm or more in consideration of the future increase in wafer size. The widths of the cylindrical light transmission region and the columnar light transmission region are not particularly limited, but are usually about 10 to 30 mm.

  In the present invention, the cylindrical resin block or the columnar resin block produced by the above method is rotated around an axis, and the surface portion of the resin block is sliced with a predetermined thickness to be composed of a polishing region and a light transmission region. A strip-shaped resin sheet is produced.

  FIG. 1 shows a cylindrical resin block 1 in which a first cylindrical polishing region 2, a cylindrical light transmission region 3, and a second cylindrical polishing region 4 are laminated in this order while rotating around a cylindrical shaft 5. It is the schematic which shows the process of slicing using the slicer 6. FIG. The rotational speed of the resin block is preferably 30 to 300 rpm. When the rotational speed is less than 30 rpm, the torque at the time of slicing becomes large. On the other hand, when it exceeds 300 rpm, heat is generated at the time of slicing and the strip-shaped resin sheet tends to be easily altered or deformed. Moreover, when slicing, the resin block is preferably heated to 80 to 120 ° C. When the temperature of the resin block is less than 80 ° C., the torque at the time of slicing increases, whereas when it exceeds 120 ° C., the belt-shaped resin sheet tends to be altered or deformed during slicing.

  The thickness of the sliced strip-shaped resin sheet 7 is not particularly limited, but is preferably 0.1 to 3 mm, and more preferably 0.5 to 1.5 mm.

  Moreover, the length of the belt-shaped resin sheet 7 is not particularly limited, but is preferably 5 m or more, and more preferably 7 m or more.

  When a grinding | polishing area | region is a foam, it is preferable that an average bubble diameter is 30-80 micrometers, More preferably, it is 30-60 micrometers. When deviating from this range, the polishing rate tends to decrease or the planarity of the polished wafer tends to decrease.

  Moreover, it is preferable that the specific gravity of a grinding | polishing area | region is 0.5-1.0. When the specific gravity is less than 0.5, the surface strength of the polishing region decreases, and the planarity of the wafer tends to decrease. On the other hand, when the ratio is larger than 1.0, the number of bubbles on the surface of the polishing region decreases and planarity is good, but the polishing rate tends to decrease.

  Moreover, it is preferable that the hardness of a grinding | polishing area | region is 45 to 65 degree | times with an Asker D hardness meter. When the Asker D hardness is less than 45 degrees, the planarity of the wafer is lowered. On the other hand, when it is larger than 65 degrees, the planarity is good, but the uniformity of the wafer tends to be lowered.

  The polishing surface in contact with the wafer in the polishing region preferably has a concavo-convex structure for holding and renewing the slurry. By forming the concavo-convex structure on the polished surface, the slurry can be held and renewed efficiently, and the wafer can be prevented from being broken due to adsorption to the wafer. The concavo-convex structure is not particularly limited as long as it is a shape that holds and renews the slurry. Examples include eccentric circular grooves, radial grooves, and combinations 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 formation method of 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 sheet with a press plate having a predetermined surface shape, Examples thereof include a method of forming using photolithography, a method of forming using a printing technique, and a forming method using laser light using a carbon dioxide laser.

  The produced belt-shaped resin sheet 7 may be used as a long polishing pad (polishing layer) as it is, and is cut into a desired shape (for example, a circle) by a cutting machine to produce a short polishing pad (polishing layer). May be. In the case of cutting into a circle, the diameter is about 30 to 100 cm, preferably 50 to 80 cm.

  The polishing pad of the present invention may be a laminate of the polishing layer and a cushion sheet (cushion layer).

  The cushion sheet supplements the characteristics of the polishing layer. The cushion sheet is necessary for achieving both planarity and uniformity in a trade-off relationship in CMP. Planarity refers to the flatness of a pattern portion when a wafer with minute irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire wafer. Planarity is improved by the characteristics of the foam sheet, and 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 region.

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

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

  The double-sided tape has a general configuration in which adhesive layers are provided on both sides of a substrate such as a nonwoven fabric or a film. In consideration of preventing the penetration of the slurry into the cushion sheet, it is preferable to use a film for the substrate. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. Considering the content of metal ions, an acrylic adhesive is preferable because the metal ion content is low. In addition, since the foam sheet and the cushion sheet may have different compositions, the composition of each adhesive layer of the double-sided tape can be made different to optimize the adhesive strength of each layer.

  The polishing pad of the present invention may be provided with a double-sided tape on the surface to be bonded to the platen. As the double-sided tape, a tape having a general configuration in which an adhesive layer is provided on both surfaces of a base material can be used as described above. As a base material, a nonwoven fabric, a film, etc. are mentioned, for example. In consideration of peeling from the platen after use of the polishing pad, it is preferable to use a film for the substrate. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. Considering the content of metal ions, an acrylic adhesive is preferable because the metal ion content is low.

  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 semiconductor wafer polishing method and polishing apparatus are not particularly limited. For example, the semiconductor wafer is polished by the following method.

  FIG. 2 is a schematic view showing a method of polishing the semiconductor wafer 8 using a web-type polishing apparatus. Initially, the long polishing pad 9 is mainly wound around the supply roll 10a. When a large number of semiconductor wafers 8 are polished, the polishing pad in the used area is wound up by the collection roll 10b, and the polishing pad in the unused area is sent out from the supply roll 10a.

  FIG. 3 is a schematic view showing a method of polishing the semiconductor wafer 8 using a linear polishing apparatus. The long polishing pad 9 is arranged in a belt shape so as to rotate around the roll 11. Then, the semiconductor wafers 8 are polished one after another on the polishing pad moving linearly.

  FIG. 4 is a schematic view showing a method of polishing the semiconductor wafer 8 using a reciprocating polishing apparatus. The long polishing pad 9 is arranged in a belt shape so as to reciprocate between the rolls 11. Then, the semiconductor wafers 8 are successively polished on the polishing pad that reciprocates left and right.

  Although not shown in the figure, the above polishing apparatus usually has a polishing surface plate (platen) for supporting a long polishing pad, a support base (polishing head) for supporting a semiconductor wafer, and uniform pressure on the wafer. A backing material for carrying out and a supply mechanism of an abrasive (slurry) are provided. The polishing surface plate and the support table are arranged so that the long polishing pad and the semiconductor wafer supported by each of the polishing table and the support table face each other, and the support table includes a rotation shaft. In polishing, the semiconductor wafer is pressed against the long polishing pad while rotating the support base, and polishing is performed while supplying slurry. The flow rate of the slurry, the polishing load, the wafer rotation speed, and the like are not particularly limited, and are adjusted as appropriate.

  When the long polishing pad of the present invention is used, many wafers can be polished with a single polishing pad, so that the working efficiency is remarkably superior to that of a conventional circular polishing pad. In addition, since the long polishing pad of the present invention is a continuous band-shaped polishing pad, the conventional belt in which peeling occurs at the end of the pad or the wafer is easily caught at the end of the pad and smooth polishing cannot be performed. The problem of the polishing pad can be completely solved.

  On the other hand, when a circular polishing pad is used, as shown in FIG. 5, a polishing surface plate 13 that supports the circular polishing pad (polishing layer) 12, a support base (polishing head) 14 that supports the semiconductor wafer 8, and the wafer. Polishing is performed by using a backing material for performing uniform pressurization and a polishing apparatus equipped with a supply mechanism for the abrasive 15. The circular polishing pad 12 is attached to the polishing surface plate 13 by attaching it with, for example, a double-sided tape. The polishing surface plate 13 and the support base 14 are arranged so that the polishing pad 12 and the semiconductor wafer 8 supported on each of the polishing surface plate 13 and the support table 14 are opposed to each other, and are provided with rotating shafts 16 and 17 respectively. Further, a pressurizing mechanism for pressing the semiconductor wafer 8 against the circular polishing pad 12 is provided on the support base 14 side. In polishing, the semiconductor wafer 8 is pressed against the polishing pad 12 while rotating the polishing surface plate 13 and the support base 14, 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.

  As a result, the protruding portion of the surface of the semiconductor wafer 8 is removed and polished flat. Thereafter, a semiconductor device is manufactured by dicing, bonding, packaging, or the like. The semiconductor device is used for an arithmetic processing device, a memory, and the like.

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

[Measuring method]
(Average bubble diameter measurement)
A sample for measuring the average bubble diameter was prepared by cutting the prepared polished region as thin as possible to a thickness of 1 mm or less in parallel with a microtome cutter. 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 measurement)
This was performed according to JIS Z8807-1976. The prepared polished area was cut into a 4 cm × 8.5 cm strip (thickness: arbitrary) and used as a specific gravity measurement sample, which was allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. . The specific gravity was measured using a hydrometer (manufactured by Sartorius).

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

Example 1
100 parts by weight of a polyether prepolymer (Auniprene L-100, manufactured by Uniroyal Co., Ltd.) adjusted to 60 ° C. and 4,4′-methylenebis (o-chloroaniline) adjusted to 120 ° C. (manufactured by Ihara Chemical Co., Ltd.) , Iharacuamine MT) 12 parts by weight were mixed and degassed. Then, the mixed solution was poured into a cylindrical mold (diameter 30 cm, through-hole diameter 3 cm) kept at 100 ° C., and post-curing was performed at 100 ° C. for 6 hours to produce a cylindrical light transmission region (thickness 10 mm). .

  In a reaction vessel, 100 parts by weight of a polyether prepolymer (Uniroy, Adiprene L-325) and 3 parts by weight of a silicon surfactant (Toray Dow Corning Silicone, SH192) are mixed, and the temperature is adjusted. Adjusted to 80 ° C. Using a stirring blade, the mixture was vigorously stirred for about 4 minutes so that bubbles were taken into the reaction system at 900 rpm. 26 parts by weight of 4,4′-methylenebis (o-chloroaniline) (Ihara Chemical Co., Ltd., Iharacamine MT) previously melted at 120 ° C. was added thereto and stirring was continued for about 1 minute to produce a cell dispersed polyurethane resin composition. A product was prepared.

  The cylindrical light transmission region is set in the center of a cylindrical mold (diameter 30 cm, through hole diameter 3 cm), and the cell-dispersed polyurethane resin composition is poured into both sides of the cylindrical light transmission region until the fluidity is lost. Precured to obtain a block. Thereafter, the block was removed from the cylindrical mold, placed in an oven, and post-cured at 110 ° C. for 6 hours to produce a cylindrical polyurethane resin block (diameter: 30 cm, length: 40 cm).

  The produced cylindrical polyurethane resin block was heated to 100 ° C. in an oven. Then, using a slicing device (manufactured by Meinan Seisakusho Co., Ltd.) while rotating the block around the axis at a speed of 5 rpm, the surface portion was continuously sliced at a thickness of 1.5 mm, and a strip-shaped polyurethane resin sheet (width) : 40 cm, length: 8 m). Next, the sheet was buffed to a thickness of 1.27 mm using a buffing machine (manufactured by Amitech), and further a groove width of 1.0 mm and a groove pitch on the surface of the polishing area using a processing machine. A long polishing pad was manufactured by processing an XY lattice groove of 5 mm and a groove depth of 0.6 mm. The average bubble diameter in the polishing region was 50 μm, the specific gravity was 0.8, and the Asker D hardness was 52 degrees.

Schematic which shows the process of slicing a cylindrical polyurethane resin block using a slicer Schematic showing a method of polishing a semiconductor wafer using a web-type polishing apparatus Schematic showing a method of polishing a semiconductor wafer using a linear polishing apparatus Schematic showing a method of polishing a semiconductor wafer using a reciprocating polishing apparatus Schematic showing an example of a polishing apparatus used in CMP polishing

Explanation of symbols

1: cylindrical resin block 2: first cylindrical polishing region 3: cylindrical light transmission region 4: second cylindrical polishing region 5: cylindrical shaft 6: slicer 7: belt-shaped resin sheet 8: semiconductor wafer 9: long polishing Pad 10a: Supply roll 10b: Collection roll 11: Roll 12: Circular polishing pad 13: Polishing surface plate 14: Support base (polishing head)
15: Abrasive agent 16, 17: Rotating shaft

Claims (7)

A step of producing a cylindrical resin block in which a cylindrical polishing region and a cylindrical light transmission region are stacked, or a columnar resin block in which a columnar polishing region and a columnar light transmission region are stacked, the axis of the resin block A method for producing a polishing pad, comprising a step of slicing a surface portion of the resin block with a predetermined thickness while rotating around the center of the resin block to produce a belt-shaped resin sheet. The cylindrical resin block has a three-layer structure in which a first cylindrical polishing region, a cylindrical light transmission region, and a second cylindrical polishing region are laminated in this order. The manufacturing method of the polishing pad of Claim 1 which has a 3 layer structure on which the 1 cylindrical polishing area | region, the cylindrical light transmission area | region, and the 2nd cylindrical polishing area | region are laminated | stacked in this order. The method for producing a polishing pad according to claim 1, wherein the polishing region is made of polyurethane foam, and the light transmission region is made of polyurethane non-foamed material. The method for manufacturing a polishing pad according to claim 1, wherein the resin block has a diameter of 10 cm or more. The manufacturing method of the polishing pad according to any one of claims 1 to 4, wherein the belt-shaped resin sheet has a thickness of 0.1 to 3 mm. The manufacturing method of the polishing pad according to any one of claims 1 to 5, wherein the belt-shaped resin sheet has a length of 5 m or more. The manufacturing method of a semiconductor device including the process of grind | polishing the surface of a semiconductor wafer using the polishing pad obtained by the manufacturing method in any one of Claims 1-6.

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