JP2008246640A - Method of manufacturing polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a polishing pad with excellent optical detection accuracy, which prevents leakage of slurry from a clearance between a polishing region and a light transmitting region. <P>SOLUTION: This method comprises processes of: producing the light transmitting region having width on one face side wider than that on the other face side; preparing a foam-dispersion urethane composition by mechanical foaming method; arranging the light transmitting region 10 in a prescribed position on a face-material or a belt conveyor with its face with wider width located on the downside while sending out the face-material or moving the belt conveyor 9; continuously discharging the foam-dispersion urethane composition on the face-material or the belt conveyor without the light transmitting region; laminating another face-material or belt conveyor on the discharged foam-dispersion urethane composition; producing a polishing sheet by forming the polishing region made of polyurethane foam by hardening the foam-dispersion urethane composition while adjusting the thickness evenly; and cutting the polishing sheet. <P>COPYRIGHT: (C)2009,JPO&INPIT

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 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.

  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.

  In addition, a method of 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 1). 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.

  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 2 and 3) 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.

  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 a transparent polymer sheet that transmits solid and homogeneous light having a wavelength of 190 nm to 3500 nm at least in part is disclosed (Patent Document 4). Further, a polishing pad in which a stepped transparent plug is inserted is disclosed (Patent Document 5). Moreover, a polishing pad having a transparent plug that is flush with the polishing surface is disclosed (Patent Document 6).

  On the other hand, proposals (Patent Documents 7 and 8) have been made to prevent the slurry from leaking from the boundary (seam) between the polishing region and the light transmission region.

  In addition, the first resin rod or plug is placed in the liquid second resin, the second resin is cured to produce a molded product, and the molded product is sliced to polish the light transmission region and the polished product. A method of manufacturing a polishing pad in which regions are integrated is disclosed (Patent Document 9). According to the manufacturing method, since the light transmission region and the polishing region are integrated, slurry leakage can be prevented to some extent.

  However, in the case of the manufacturing method of Patent Document 9, when the first resin rod or plug is disposed in the liquid second resin, a void (hole) is generated at the interface between the two resins, and the slurry is formed from the void. There was a leak. Moreover, the method of patent document 9 cannot be employ | adopted when producing a elongate polishing pad.

JP 2004-169038 A 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 JP 2005-210143 A

  It is an object of the present invention to provide a method for manufacturing a polishing pad that can prevent slurry leakage from between a polishing region and a light transmission region and has excellent optical detection accuracy.

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

  That is, the manufacturing method of the polishing pad of the first aspect of the present invention includes a step of producing a light transmission region having a width on one side larger than the width on the other side, a step of preparing a cell-dispersed urethane composition by a mechanical foaming method, Disposing the light transmission region at a predetermined position on the face material or on the belt conveyor while feeding the material or moving the belt conveyor, with the surface having a large width facing down; The step of continuously discharging the cell-dispersed urethane composition on the face material or the belt conveyor which is not, the step of laminating another surface material or the belt conveyor on the discharged cell-dispersed urethane composition, the thickness A step of forming a polishing region comprising a polyurethane foam by curing the cell-dispersed urethane composition while uniformly adjusting, and cutting the polishing sheet Comprising the step.

  The polishing pad manufacturing method of the second aspect of the present invention includes a step of producing a light transmission region where the width on one side is larger than the width on the other side, a step of preparing a cell-dispersed urethane composition by mechanical foaming, a mold A step of disposing the light transmissive region at a predetermined position in the lower surface with a surface having a large width on the lower side, a step of injecting the cell dispersed urethane composition into a mold in which the light transmissive region is not disposed, and the bubbles The process includes forming a polishing region made of a polyurethane foam by curing the dispersed urethane composition to produce an abrasive sheet.

  According to the above manufacturing method, by using a light transmission region having a width on one side larger than the width on the other side, and arranging the light transmission region with the surface having a large width on the lower side, both sides of the light transmission region or When the cell-dispersed urethane composition is discharged to the surroundings, the cell-dispersed urethane composition is sequentially filled along the slope of the light transmission region, so that it is difficult to entrap air and effectively prevent the generation of voids. Can do. The polishing pad of the present invention has no void at the interface between the polishing region and the light transmission region, and the adhesion between both regions is very high, so that it is possible to effectively prevent slurry leakage between the polishing region and the light transmission region. be able to.

  The light transmitting region preferably has a trapezoidal cross-sectional shape. Further, in the case of a strip-shaped light transmission region, it is preferable that both the cross-sectional shapes in the width direction and the length direction are trapezoidal.

  The width on one side is preferably 1.1 to 4 times the width on the other side. When the width on one side is less than 1.1 times the width on the other side, the slope of the side surface of the light transmission region becomes tight and close to the vertical surface, so air is discharged when discharging the cell dispersed urethane composition. It becomes easy to bite, and as a result, voids are likely to occur. On the other hand, when it exceeds 4 times, the volume of the light transmission region is increased, so that the rigidity of the polishing pad is lowered and the polishing characteristics such as the flattening characteristics tend to be adversely affected.

  The polishing region in the present invention is made of a polyurethane foam having fine bubbles, and can be formed by curing the cell-dispersed urethane composition. Polyurethane is a preferred material for forming the 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.

  The polyurethane is made from an isocyanate component, a polyol component (high molecular weight polyol, low molecular weight polyol), a chain extender, and the like.

  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 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.

  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.

  The ratio of the high molecular weight polyol to the low molecular weight polyol in the polyol component is determined by the characteristics required for the polishing region produced therefrom.

  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 region. 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 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.

  The polyurethane foam is produced by curing a cell-dispersed urethane composition obtained by mixing a first component containing an isocyanate group-containing compound and a second component containing an active hydrogen group-containing compound. In the prepolymer method, the isocyanate-terminated prepolymer becomes an isocyanate group-containing compound, and the chain extender becomes an active hydrogen group-containing compound. In the one-shot method, the isocyanate component becomes an isocyanate group-containing compound, and the chain extender and the polyol component become active hydrogen group-containing compounds.

  The cell-dispersed urethane composition is prepared by a mechanical foaming method (including a mechanical floss method). 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 Silicon) and the like are exemplified as suitable compounds. The addition amount of the silicon-based surfactant is preferably 0.05 to 5% by weight in the polyurethane foam. When the amount of the silicon-based surfactant is less than 0.05% by weight, a fine-bubble foam tends to be not obtained. On the other hand, if it exceeds 5% by weight, it tends to be difficult to obtain a polyurethane foam with high hardness due to the plastic effect of the silicon surfactant.

  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 preparing the cell-dispersed urethane composition will be described below. The method for preparing such a cell dispersed urethane composition 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 prepare a cell dispersed urethane composition.

  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.

  You may add the catalyst which accelerates | stimulates well-known polyurethane reactions, such as a tertiary amine type | system | group, to a cell dispersion | distribution urethane composition. The type and addition amount of the catalyst are selected in consideration of the flow time for pouring the cell-dispersed urethane composition into the mold after the mixing step or the curing time after being discharged onto the face material.

  The light transmission region enables high-precision optical end point detection in a state where polishing is performed, and the light transmittance is preferably 40% or more over the entire wavelength range of 300 to 800 nm, more preferably the light transmittance. 50% or more.

  Examples of the material for the light transmission region include thermosetting resins such as polyurethane resin, polyester resin, phenol resin, urea resin, melamine resin, epoxy resin, and acrylic resin; polyurethane resin, polyester resin, polyamide resin, and cellulose resin. , Thermoplastic resins such as acrylic resins, polycarbonate resins, halogen resins (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, and olefin resins (polyethylene, polypropylene, etc.); such as ultraviolet rays and electron beams Examples thereof include a photocurable resin that is cured by light and a photosensitive resin. These resins may be used alone or in combination of two or more.

  The light transmission region of the present invention needs to have a shape in which the width on one side is larger than the width on the other side, and the cross-sectional shape is not particularly limited, but the cut surface in the width direction is trapezoidal Is preferred. In the case of a strip-shaped light transmission region, it is preferable that both the cross-sectional shapes in the width direction and the length direction are trapezoidal.

  The light transmissive region having the shape can be produced by, for example, an extrusion molding method or a casting molding method.

  Moreover, you may produce the light transmissive area | region of the target shape by making a cutting blade contact diagonally with respect to the resin sheet formed from the said material, and cut | disconnecting.

  Moreover, the light transmission area | region of the target shape can be produced by cut | disconnecting the cylindrical resin block or columnar resin block formed from the said material using the cutting blade of predetermined shape. A long light transmission region can be produced by cutting in a spiral shape.

  The light transmission region may be long or strip-shaped, and is produced according to the shape of the intended polishing pad (long shape, circular shape, etc.). In the case of a long shape, the length is usually about 5 m, preferably 8 m or more. The height of the light transmission region can be adjusted as appropriate in relation to the polishing region, but is usually about 0.5 to 3 mm, preferably 0.8 to 2 mm.

  The width of the light transmission region is usually about 4 to 60 mm, preferably 7 to 26 mm on one side, and usually about 3 to 15 mm, preferably 6 to 13 mm on the other side. Moreover, it is preferable that the width | variety of one side is 1.1 to 4 times the width | variety of the other surface side, More preferably, it is 1.1 to 2 times.

  Although the hardness of the light transmission region is not particularly limited, it is preferably 30 to 60 degrees, more preferably 35 to 54 degrees in terms of Asker D hardness. If it is less than 30 degrees, the light transmission region is likely to be deformed, so that stable optical end point detection is difficult, and if it exceeds 60 degrees, scratches tend to occur on the surface of the material to be polished.

  The face material used in the present invention is not particularly limited, and examples thereof include paper, cloth, non-woven fabric, and resin film. A resin film having heat resistance and flexibility is particularly preferable.

  Examples of the resin forming the face material include polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, polyfluoroethylene, and other fluorine-containing resins, nylon, and cellulose.

  The thickness of the face material is not particularly limited, but is preferably about 20 to 200 μm from the viewpoint of strength and winding. The width of the face material is not particularly limited, but is preferably about 60 to 250 cm in consideration of the required size of the polishing layer.

  The surface of the face material is preferably subjected to a release treatment. Thereby, after producing the polishing layer, the peeling operation of the face material can be easily performed.

  Hereinafter, a method for producing the polishing pad of the present invention will be described. FIG. 2 is a schematic view showing an example of the manufacturing process of the polishing pad of the present invention.

  The face material 8 delivered from the roll moves on the belt conveyor 9. In addition, you may use the belt conveyor 9 which performed the mold release process, without using the face material 8. FIG. First, it arrange | positions by sending out the light transmissive area | region 10 to the predetermined position of the face material 8 or the belt conveyor 9 from a roll. In that case, it is necessary to arrange the light transmission region 10 with the surface having a large width facing down. One light transmission region 10 may be provided in the approximate center of the face material 8 or the belt conveyor 9, or two or more light transmission regions 10 may be provided at predetermined intervals. However, if the number of the light transmission regions 10 is too large, the area of the polishing region involved in the polishing becomes relatively small, which is not preferable from the viewpoint of polishing characteristics. Therefore, for example, when the face material 8 or the belt conveyor 9 having a width of about 60 to 100 cm is used, the number of the light transmission regions 10 is preferably 1 to 3. In addition, the long light transmission region 10 is continuously arranged as shown in FIG. 2, and is intermittently arranged when a strip-like light transmission region is used.

  Thereafter, the cell-dispersed urethane composition 11 is continuously discharged from the discharge nozzle of the mixing head 12 onto the face material 8 or the belt conveyor 9 where the light transmission region 10 is not disposed. The moving speed of the face material 8 or the belt conveyor 9 and the discharge amount of the cell dispersed urethane composition 11 are appropriately adjusted in consideration of the thickness of the polishing layer.

  Thereafter, the foam material is laminated by laminating a face material 13 or a belt conveyor (not shown) on the discharged cell-dispersed urethane composition 11 and curing the cell-dispersed urethane composition 11 while adjusting the thickness uniformly. A long polishing sheet is obtained by forming a polishing region consisting of Examples of means for uniformly adjusting the thickness include a roll 14 such as a nip roll and a coater roll, a doctor blade, and the like. Moreover, hardening of the cell-dispersed urethane composition 11 is performed, for example, by passing through a heating oven (not shown) provided on the belt conveyor after the thickness is uniformly adjusted. The heating temperature is about 40 to 100 ° C., and the heating time is about 5 to 10 minutes. Heating and post-curing the cell-dispersed urethane composition 11 that has reacted until it no longer flows has the effect of improving the physical properties of the polyurethane foam.

  The obtained long abrasive sheet is cut into, for example, a several meter piece by a cutting machine. The length is appropriately adjusted according to the polishing apparatus to be used, but is usually about 5 to 10 m. Then, a long polishing layer is produced through the process of peeling a post-cure and a face material. In addition, it may be post-cured before peeling off the face material, or post-cure after peeling off the face material. However, since the heat shrinkage rate is usually different between the face material and the polishing sheet, the polishing sheet may be deformed. From the viewpoint of preventing, it is preferable to post-cure after peeling off the face material. After the post cure, the end of the long abrasive sheet may be cut and removed in order to adjust the length and make the thickness uniform. Further, the long polishing sheet becomes a long polishing layer through a step of forming a concavo-convex structure on the polishing surface.

  The obtained long abrasive sheet is first cut into a shape slightly larger than a desired shape (for example, a circle, a square, a rectangle, etc.) with a cutting machine, for example, and then the post-cure and the face material are peeled off. A polishing sheet may be produced through the above. When cutting, the light transmission region is cut so as to be arranged at a predetermined position of the polishing sheet. In addition, it may be post-cured before peeling off the face material, or post-cure after peeling off the face material. However, since the heat shrinkage rate is usually different between the face material and the polishing sheet, the polishing sheet may be deformed. From the viewpoint of preventing, it is preferable to post-cure after peeling off the face material. 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. Thereafter, the polishing sheet becomes a polishing layer through a process of forming an uneven structure on the polishing surface.

  Further, another method for producing the polishing pad of the present invention will be described. FIG. 3 is a schematic view showing an example of the manufacturing process of the polishing pad of the present invention.

  First, the light transmission region 10 is arranged at a predetermined position in the mold 15. In that case, it is necessary to arrange the light transmission region 10 with the surface having a large width facing down. The shape of the mold 15 is not particularly limited, and may be circular or rectangular. The size of the mold 15 can be appropriately set in consideration of the required size of the polishing layer, but in the case of a circular shape, the diameter is usually about 50 to 200 cm, preferably 50 to 100 cm. Further, the height of the mold 15 is not particularly limited, but is preferably about 10 to 60 mm from the viewpoint of the required thickness of the polishing region and prevention of overflow during casting.

  Thereafter, the cell-dispersed urethane composition 11 is poured into the mold 15 and the cell-dispersed urethane composition 11 is cured to form a polishing region made of a polyurethane foam to obtain a polishing sheet. The discharge amount of the cell dispersed urethane composition 11 is appropriately adjusted in consideration of the thickness of the light transmission region 10 and the thickness of the polishing region.

  Curing of the cell-dispersed urethane composition 11 is performed, for example, by adjusting the thickness uniformly and then carrying the mold into a heating oven. The heating temperature is about 40 to 100 ° C., and the heating time is about 5 to 10 minutes.

  The obtained polishing sheet may be post-cured, or the size may be adjusted appropriately according to the polishing apparatus to be used. Furthermore, the polishing sheet becomes a polishing layer through a step of forming a concavo-convex structure on the polishing surface.

  The average cell diameter of the polyurethane foam is preferably 30 to 80 μm, more preferably 30 to 60 μm. When deviating from this range, the polishing rate tends to decrease, or the planarity of the polished material (wafer) after polishing tends to decrease.

  The thickness of the polishing layer is not particularly limited, but is usually about 0.8 to 4 mm, and preferably 1.2 to 2.5 mm.

  The specific gravity of the polishing layer is preferably 0.5 to 1.0. When the specific gravity is less than 0.5, the strength of the surface of the polishing layer decreases, and the planarity (flatness) of the material to be polished tends to deteriorate. On the other hand, when the ratio is larger than 1.0, the number of fine bubbles on the surface of the polishing layer is reduced and the planarization characteristics are good, but the polishing rate tends to deteriorate.

  Further, the hardness of the polishing layer is preferably 45 to 65 degrees as measured by an Asker D hardness meter. When the D hardness is less than 45 degrees, the planarity (flatness) of the material to be polished tends to deteriorate. On the other hand, when the angle is larger than 65 degrees, the planarity is good, but the uniformity (uniformity) of the material to be polished tends to deteriorate.

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

  Examples of a method for suppressing the thickness variation of the polishing layer include a method of buffing the surface of the polishing layer with a buffing machine. In addition, when buffing, it is preferable to perform in stages with abrasives having different particle sizes.

  In the polishing layer of the present invention, the polishing surface that comes into contact with the material to be polished (wafer) preferably has an uneven 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 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 the slurry. For example, an XY lattice groove, a concentric circular groove, a through hole, a non-penetrating hole, a polygonal column, a cylinder, a spiral groove, 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 concavo-convex structure may be formed on either surface of the produced polishing sheet, but is preferably formed on the surface side where the width of the light transmission region 10 is small. This is because it is preferable to form the concavo-convex structure on the surface having the larger area of the polishing region substantially involved in polishing in consideration of polishing efficiency.

  The production 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 resin with a press plate having a predetermined surface shape, And a production method using a laser beam using a carbon dioxide laser or the like.

  The polishing pad of the present invention may be only the (long) polishing layer, or may be a laminate of the (long) polishing layer and another layer (for example, a cushion layer, a transparent support film, etc.).

  The cushion layer supplements the characteristics of the polishing layer. The cushion layer is necessary in order to achieve 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 layer. In the polishing pad of the present invention, it is preferable to use a cushion layer that is softer than the polishing region.

  Examples of the cushion layer 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 the means for attaching the polishing layer and the cushion layer include a method in which the polishing layer and the cushion layer are sandwiched and pressed with a double-sided tape. In addition, it is preferable not to provide a cushion layer in a portion corresponding to the light transmission region.

  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 slurry from penetrating into the cushion layer, 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 transparent support film is preferably a resin film having high transparency, heat resistance and flexibility. Examples of the material of the resin film include polyester; polyethylene; polypropylene; polystyrene; polyimide; polyvinyl alcohol; polyvinyl chloride; fluorine-containing resin such as polyfluoroethylene; nylon; cellulose; general-purpose engineering plastics such as polycarbonate; And special engineering plastics such as polyetheretherketone and polyethersulfone.

  The thickness of the transparent support film is not particularly limited, but is preferably about 20 to 200 μm from the viewpoints of strength and winding. In the case of producing a long polishing pad, the length of the transparent support film can be appropriately set in accordance with the required length of the long polishing layer. It is about ~ 15m.

  Examples of means for bonding the polishing layer and the transparent support film include a method of sandwiching and pressing the polishing layer and the transparent support film with a double-sided tape. Moreover, you may produce a laminated body using a transparent support film instead of a face material at the time of preparation of a long polishing sheet. Moreover, you may produce a laminated body by providing a transparent support film beforehand in the mold 15 at the time of preparation of an abrasive sheet.

  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 long 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. 4 is a schematic view showing a method for polishing a semiconductor wafer using a web-type polishing apparatus. First, the long polishing pad 16 is mainly wound around the supply roll 17a. When a large number of semiconductor wafers 4 are polished, the polishing pad in the used area is wound up by the collection roll 17b, and the polishing pad in the unused area is sent out from the supply roll 17a.

  FIG. 5 is a schematic view showing a method for polishing a semiconductor wafer using a linear polishing apparatus. The long polishing pad 16 is arranged in a belt shape so as to rotate around the roll 18. Then, the semiconductor wafers 4 are polished one after another on the polishing pad moving linearly.

  FIG. 6 is a schematic view showing a method for polishing a semiconductor wafer using a reciprocating polishing apparatus. The long polishing pad 16 is arranged in a belt shape so as to reciprocate between the rolls 18. Then, the semiconductor wafers 4 are polished one after another 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.

  The semiconductor device is manufactured through a process of polishing the surface of the semiconductor wafer using the polishing pad. For example, as shown in FIG. 1, a polishing surface plate 2 that supports a polishing pad 1, a support table (polishing head) 5 that supports a semiconductor wafer 4, a backing material for uniformly pressing the wafer, and polishing This is performed using a polishing apparatus equipped with a supply mechanism of the agent 3. 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.

  As a result, the protruding portion of the surface of the semiconductor wafer 4 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.

[Measurement of number of voids (pieces / 5m)]
The number of voids at the interface between the polishing region and the light transmission region of the produced long polishing pad was visually counted. A hole having a diameter of 0.5 mm or more was defined as a void.

[Evaluation of flatness]
Using SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) as the polishing apparatus, the flatness was evaluated using the prepared polishing pad. The flatness is evaluated by depositing a thermal oxide film of 0.5 μm on an 8-inch silicon wafer, and then patterning L / S (line and space) = 270 μm / 30 μm and L / S = 30 μm / 270 μm. Then, a 1 μm thick oxide film (TEOS) was further deposited to fabricate a patterned wafer with an initial step of 0.5 μm. This wafer was polished under the following polishing conditions and evaluated by measuring the amount of scraping of the bottom portion of the 270 μm space when the global level difference was 2000 mm or less. It can be said that the flatness is better as the amount of scraping is smaller. An interference type film thickness measuring device (manufactured by Otsuka Electronics Co., Ltd.) was used for measuring the thickness of the oxide film. As the polishing conditions, silica slurry (SS12 Cabot) was added as a slurry at a flow rate of 150 ml / min during polishing. The polishing load was 350 g / cm ² , the polishing platen rotation number was 35 rpm, and the wafer rotation number was 30 rpm.

(Water leak evaluation)
SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used as a polishing apparatus, and water leakage was evaluated using the prepared polishing pad. An 8-inch dummy wafer was polished and visually observed whether there was water leakage on the back side of the light transmission region every predetermined time, and water leakage was evaluated according to the following criteria. The evaluation results are shown in Table 1. As polishing conditions, silica slurry (SS12, manufactured by Cabot Corporation) was added as a slurry at a flow rate of 150 ml / min during polishing, so that the polishing load was 350 g / cm ² , the polishing platen rotation was 35 rpm, and the wafer rotation was 30 rpm. . The wafer was polished while dressing the surface of the polishing pad using a # 100 dresser. The dressing conditions were a dress load of 80 g / cm ² and a dresser rotational speed of 35 rpm.
○: No slurry leakage was observed on the back side of the light transmission region.
X: Slurry leakage is observed on the back side of the light transmission region.

Production Example Toluene diisocyanate (mixture of 2,4-isomer / 2,6-isomer = 80/20) 32 parts by weight, 8 parts by weight of 4,4′-dicyclohexylmethane diisocyanate, 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). A mixture A was prepared by mixing 100 parts by weight of the isocyanate-terminated prepolymer and 3 parts by weight of a silicone surfactant (SH-192, manufactured by Toray Dow Silicone Co., Ltd.) and adjusting the temperature to 80 ° C. 80 parts by weight of the mixture A and 20 parts by weight of 4,4′-methylenebis (o-chloroaniline) (Ihara Chemical amine, Ihara Chemical amine) melted at 120 ° C. were mixed in a mixing chamber, and air was mixed at the same time. A cell-dispersed urethane composition was prepared by mechanically stirring the mixture therein.

Example 1
Into a container, 770 parts by weight of 1,6-hexamethylene diisocyanate and 230 parts by weight of 1,3-butanediol were placed and heated and stirred at 80 ° C. for 120 minutes to prepare an isocyanate-terminated prepolymer. Further, 29 parts by weight of polytetramethylene glycol having a number average molecular weight of 650, 13 parts by weight of trimethylolpropane, and 0.43 parts by weight of a catalyst (manufactured by Kao, Kao No. 25) are mixed and stirred at 80 ° C. Obtained. Thereafter, 100 parts by weight of the isocyanate-terminated prepolymer was added to the mixture whose temperature was adjusted to 80 ° C., and the mixture was sufficiently stirred with a hybrid mixer (manufactured by Keyence Corporation), and then defoamed. This reaction solution is dropped onto a mold (12. 2 mm wide on the other side, 9.8 mm wide on the other side) that has been subjected to a release treatment, and the release-treated PET film is placed thereon, and the thickness is adjusted with a nip roll. did. Thereafter, the mold was placed in an oven at 100 ° C. and post-cured for 16 hours to produce a long light transmission region A having a trapezoidal cross-sectional shape in the width direction. Thereafter, both surfaces of the long light transmission region A were buffed to adjust the width on one side to 12 mm and the width on the other side to 10 mm. The width on one side is 1.2 times the width on the other side.

  While sending out a face material (thickness 50 μm, width 100 cm) made of polyethylene terephthalate (PET), the long light transmission region A was arranged at the center of the face material with the face having a large width on the lower side. Thereafter, the cell-dispersed urethane composition was continuously discharged onto a face material on which the long light transmission region A was not disposed. Then, the cell-dispersed urethane composition was covered with another face material made of PET (thickness 50 μm, width 100 cm), and the thickness was uniformly adjusted using a nip roll. Thereafter, the composition was cured by heating to 80 ° C. to form a long polishing region made of a polyurethane foam to obtain a long polishing sheet. Thereafter, the long abrasive sheet was cut to a length of 7 m, the face material was peeled off, and post-cured at 110 ° C. for 6 hours. Next, the surface of the long abrasive sheet was buffed using a buffing machine (manufactured by Amitech) to adjust the thickness to 1.27 mm. And the long polishing pad was produced by giving a groove | channel process on the grinding | polishing surface of this long polishing sheet using the groove processing machine (made by Toho Steel Machine Co., Ltd.).

Example 2
The reaction solution described in Example 1 was dropped on a mold (width 18.6 mm on one side, width 9.4 mm on the other side) subjected to a release treatment, and a release-treated PET film was placed thereon, and the nip roll was covered. The thickness was adjusted. Thereafter, the mold was placed in an oven at 100 ° C. and post-cured for 16 hours to produce a long light transmission region B having a trapezoidal cross-sectional shape in the width direction. Thereafter, both sides of the long light transmission region B were buffed to adjust the width on one side to 18 mm and the width on the other side to 10 mm. The width on one side is 1.8 times the width on the other side.

  A long polishing pad was prepared in the same manner as in Example 1 except that the long light transmission region B was used instead of the long light transmission region A.

Example 3
The reaction solution described in Example 1 was dropped on a mold (26.2 mm wide on one side, 8.8 mm wide on the other side) subjected to a release treatment, and the release-treated PET film was placed on the mold, and the nip roll was covered. The thickness was adjusted. Thereafter, the mold was put in an oven at 100 ° C. and post-cured for 16 hours to produce a long light transmission region C having a trapezoidal cross-sectional shape in the width direction. Thereafter, both sides of the long light transmission region C were buffed to adjust the width on one side to 25 mm and the width on the other side to 10 mm. The width on one side is 2.5 times the width on the other side.

  A long polishing pad was produced in the same manner as in Example 1 except that the long light transmission region C was used instead of the long light transmission region A.

Comparative Example 1
The reaction solution described in Example 1 was dropped onto a mold (10 mm width on one side, 10 mm width on the other side) which was subjected to a release treatment, and the release-treated PET film was placed thereon, and the thickness was adjusted with a nip roll. did. Thereafter, the mold was put in an oven at 100 ° C. and post-cured for 16 hours to produce a long light transmission region D having a trapezoidal cross-sectional shape in the width direction. The width on the other side is one time the width on the one side.

  A long polishing pad was produced in the same manner as in Example 1 except that the long light transmission region D was used instead of the long light transmission region A.

表１から明らかなように、実施例１〜３の研磨パッドは、研磨領域と光透過領域との界面にボイドがほとんどなく、両領域の密着性が非常に高いため研磨領域と光透過領域との間からのスラリー漏れを効果的に防止できることがわかる。

As is clear from Table 1, the polishing pads of Examples 1 to 3 have almost no voids at the interface between the polishing region and the light transmission region, and the adhesion between both regions is very high. It turns out that the slurry leak from between can be prevented effectively.

Schematic configuration diagram showing an example of a polishing apparatus used in CMP polishing Schematic which shows the example of the manufacturing process of the long abrasive sheet of this invention Schematic which shows the example of the manufacturing process of the abrasive sheet of this invention 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

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 shafts 8, 13: Face material 9: Belt conveyor 10: Light transmission region 11: Bubble dispersion urethane composition 12: Mixing head 14: Roll 15: Mold 16: Long polishing pad 17a: Supply roll 17b: Collection roll 18: Roll

Claims (4)

A step of producing a light transmission region where the width on one side is larger than the width on the other side, a step of preparing a cell-dispersed urethane composition by a mechanical foaming method, the face material while feeding the face material or moving the belt conveyor The step of disposing the light transmission region at a predetermined position on the top or on the belt conveyor, with the wide surface facing down, the bubble-dispersed urethane on the face material or the belt conveyor on which the light transmission region is not disposed A step of continuously discharging the composition, a step of laminating another face material or a belt conveyor on the discharged cell-dispersed urethane composition, and curing the cell-dispersed urethane composition while uniformly adjusting the thickness. The manufacturing method of the polishing pad including the process of forming the grinding | polishing area | region which consists of a polyurethane foam by this, and producing the polishing sheet, and the process of cutting the said polishing sheet. A process for producing a light transmission region where the width on one side is larger than the width on the other side, a process for preparing a cell-dispersed urethane composition by a mechanical foaming method, and a surface with a large width at the predetermined position in the mold The step of disposing the light transmission region, the step of injecting the cell-dispersed urethane composition into a mold in which the light-transmitting region is not disposed, and polishing comprising a polyurethane foam by curing the cell-dispersed urethane composition A method for producing a polishing pad, comprising a step of forming a region to produce a polishing sheet. The method for manufacturing a polishing pad according to claim 1, wherein a cross-sectional shape of the light transmission region is a trapezoid. The method for manufacturing a polishing pad according to any one of claims 1 to 3, wherein the width on one side is 1.1 to 4 times the width on the other side.

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