JP2017117976A - Abrasive pad and method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive pad which is less likely to cause a scratch on the wafer surface, is capable of performing highly accurate optical endpoint detection stably, and to provide a method of manufacturing a semiconductor device using the abrasive pad.SOLUTION: In an abrasive pad having a polishing region and a light transmission region, the surface of the light transmission region is recessed from the surface of the polishing region on the center side of the abrasive pad, and the abrasive pad has such an inclination that the outer peripheral side becomes higher, from the center side of the abrasive pad toward the outer peripheral side.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a polishing pad used when planarizing unevenness on a wafer surface by chemical mechanical polishing (CMP), and more specifically, a window (light transmission region) for detecting a polishing state or the like by optical means. The present invention relates to a polishing pad having a semiconductor device and a method for manufacturing a semiconductor device using the polishing pad.

  When manufacturing a semiconductor device, a process of forming a conductive film on the wafer surface and forming a wiring layer by photolithography, etching, or the like, a process of forming an interlayer insulating film on the wiring layer, etc. These steps are performed, and irregularities made of a conductor such as metal or an insulator are generated 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, a CMP method 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 an object to be polished (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 object to be polished 4 supported on 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. The support 5 is provided with a pressurizing mechanism for pressing the object 4 to be polished against the polishing pad 1.

  When performing such 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 1 and 2) are becoming mainstream. Specifically, the optical detection means detects the end point of polishing 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.

Examples of the polishing pad having a window include a polishing pad in which the polishing region and the light transmission region are in the same plane, and a polishing pad in which the surface of the light transmission region is recessed from the surface of the polishing region (Patent Document 3, 4).
Japanese Patent Laid-Open No. 9-7985 Japanese Patent Laid-Open No. 9-36072 JP 2003-260658 A JP 2014-104521 A

  However, in the polishing pad described in Patent Document 3, since the polishing region and the light transmission region are in the same plane, the surface of the light transmission region that is harder than the polishing region is in contact with the object to be polished during polishing. Scratches are likely to occur on the surface of the object to be polished.

  In the polishing pad described in Patent Document 4, since the surface of the light transmission region is recessed from the surface of the polishing region, it is possible to suppress the occurrence of scratches due to the light transmission region contacting the object to be polished. Since the slurry is likely to be deposited in the recessed portion during polishing, scratches due to the slurry are likely to occur. In addition, when slurry is deposited on the recessed portion, the transmission of the light beam is interrupted, so that the optical end point detection accuracy decreases.

  That is, there has not been a polishing pad that can hardly cause scratches on the surface of an object to be polished and can stably detect an optical end point with high accuracy, and a method of manufacturing a semiconductor device using the polishing pad.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing pad that is less likely to cause scratches on the wafer surface and that can stably perform high-precision optical end point detection, and a method of manufacturing a semiconductor device using the polishing pad. .

  The present invention is a polishing pad having a polishing region and a light transmission region, wherein the surface of the light transmission region is recessed at the center side of the polishing pad than the surface of the polishing region, and the center side of the polishing pad The polishing pad has a gradient such that the outer peripheral side becomes higher from the outer periphery toward the outer peripheral side.

  The present invention is a method for manufacturing a semiconductor device including a step of polishing a surface of a semiconductor wafer using the polishing pad.

  The center side of the polishing pad on the surface on the polishing region side of the light transmission region according to the polishing pad of the present invention is recessed from the surface of the polishing region. Therefore, the area where the light transmission region contacts the object to be polished can be reduced as compared with the case where the surface of the polishing region and the surface of the light transmission region are on the same plane, and the light transmission region is to be polished during polishing. Scratch generation due to contact with an object can be suppressed. Slurry is deposited on the portion where the surface of the light transmission region is recessed from the surface of the polishing region, but the polishing pad is higher on the outer peripheral side from the center side to the outer peripheral side of the polishing pad. Therefore, the slurry accumulated in the recessed portion is moved in the direction of the outer peripheral portion along the gradient and discharged from the recessed portion due to the centrifugal force generated by the rotation of the polishing pad during polishing. Therefore, it is possible to stably detect the optical end point while suppressing generation of scratches on the wafer surface due to the slurry. Therefore, according to the present invention, it is possible to provide a polishing pad that is unlikely to cause scratches on the wafer surface and that can stably perform high-precision optical end point detection, and a semiconductor device manufacturing method using the polishing pad. Can do.

Schematic configuration diagram showing an example of a polishing apparatus used in CMP polishing Schematic which shows the polishing pad of 1st Embodiment. Schematic which shows the cross section of the polishing pad of 1st Embodiment. Schematic which expanded a part of cross section of the polishing pad of 1st Embodiment. Schematic which expanded a part of cross section of the polishing pad of 1st Embodiment. Schematic which expanded a part of cross section of the polishing pad of 1st Embodiment. Schematic which shows the polishing pad of 2nd Embodiment. Schematic which shows the cross section of the polishing pad of 2nd Embodiment. Schematic which expanded a part of cross section of the polishing pad of 2nd Embodiment. Schematic which shows the cross section of the light transmission area | region which concerns on Example 1. FIG. Schematic which shows the cross section of the polishing pad which concerns on Example 1. FIG. Schematic which shows the cross section of the light transmissive area | region which concerns on Example 2. FIG. Schematic which shows the cross section of the polishing pad which concerns on Example 2. FIG. Schematic which shows the cross section of the light transmission area | region which concerns on Example 3. FIG. Schematic which shows the cross section of the polishing pad which concerns on Example 3. FIG. Schematic which shows the cross section of the light transmissive area | region which concerns on the comparative example 1. Schematic which shows the cross section of the polishing pad which concerns on the comparative example 1 Schematic which shows the cross section of the light transmissive area | region which concerns on the comparative example 2. Schematic which shows the cross section of the polishing pad which concerns on the comparative example 2

  The polishing pad of the present embodiment is a polishing pad having a polishing region and a light transmission region, and the surface of the light transmission region is recessed on the center side of the polishing pad from the surface of the polishing region. It has a gradient such that the outer peripheral side becomes higher from the center side of the pad toward the outer peripheral side.

<First Embodiment>
The polishing pad of the first embodiment will be described with reference to FIGS.

  FIG. 2 is a schematic view showing an example of the polishing pad 10 of the present embodiment. As shown in FIG. 2, the polishing pad 10 has a polishing layer 11 and a light transmission region 12. The light transmission region 12 is provided in the opening 14 of the polishing layer 11. The polishing layer 11 has a polishing region 13 on its surface.

  FIG. 3 is a schematic cross-sectional view of the polishing pad 10 shown in FIG. 2 cut in the AB direction. As shown in FIG. 3, the light transmission region 12 is provided in an opening 14 that penetrates the polishing layer 11, and the center side of the polishing pad 10 on the surface of the light transmission region 12 on the polishing region 13 side is The surface of the polishing region 13 is recessed.

  4 is an enlarged schematic view of the vicinity of the light transmission region 12 in the schematic cross-sectional view of the polishing pad 10 shown in FIG. As shown in FIG. 4, the end 124 on the center side of the polishing pad 10 on the surface of the light transmission region 12 on the polishing region 13 side is in contact with the wall surface 141 of the opening 14. As shown in FIG. 5, the end 124 on the center side of the polishing pad 10 on the surface of the light transmission region 12 on the polishing region 13 side is a surface of the light transmission region 12 opposite to the polishing region 13. The polishing pad 10 may be in contact with the central end of the polishing pad 10.

  As shown in FIG. 4, the surface of the light transmission region 12 on the polishing region 13 side has a gradient such that the outer peripheral side becomes higher from the center side of the polishing pad 10 toward the outer peripheral side. The surface of the light transmission region 12 on the polishing region 13 side may be a flat surface, or the entire surface or a part thereof may have a curvature, but the slurry is efficiently discharged by centrifugal force during polishing. A plane is preferable from the viewpoint.

  As shown in FIG. 4, the end 125 on the outer peripheral side of the polishing pad 10 on the surface of the light transmission region 12 on the polishing region 13 side is in contact with the end of the polishing region 13. The end portion 125 may be in contact with the end portion of the polishing region 13 as shown in FIG. 4 or may be in contact with the wall surface 142 on the outer peripheral side of the polishing pad 10 of the opening portion 14. However, from the viewpoint of efficiently discharging the slurry by centrifugal force during polishing, the end 125 is preferably in contact with the end of the polishing region 13.

  In FIG. 4, the end 125 of the light transmission region 12 is in contact with the end of the polishing region 13 in a state having a gradient, but as shown in FIG. The end portion 125 may be in contact with the end portion of the polishing region 13 in a state having the same plane as the polishing region 13.

  In FIG. 4, the center side of the polishing pad 10 on the surface of the light transmission region 12 on the polishing region 13 side, and a surface S parallel to the polishing region 13 including the contact points of the wall surface 141 and the light transmission region 12. The gradient 121, which is an angle, can be appropriately changed depending on the thickness of the polishing layer 11 and the size of the light transmission region 12, but is 60 ° or less from the viewpoint of efficiently discharging the slurry by centrifugal force during polishing. Preferably, 45 degrees or less is more preferable. However, when the gradient 121 becomes smaller, the amount of dent h from the polishing region 13 in the light transmission region 12 becomes smaller. When the dent amount h is small, when the polishing region 13 and the upper part of the light transmission region 12 are worn by polishing or dressing process (shaping process), the area where the upper part of the light transmission region 12 contacts the object to be polished is early. This increases the scratch on the object to be polished. Therefore, the gradient 121 is preferably 0.5 ° or more, and more preferably 1 ° or more, from the viewpoint of suppressing generation of scratches on the object to be polished.

  The angle 122 between the gradient of the surface of the light transmission region 12 on the polishing region 13 side on the outer peripheral side of the polishing pad 10 and the plane including the polishing region 13 is the thickness of the polishing layer 11 and the size of the light transmission region 12. However, from the viewpoint of efficiently discharging the slurry by centrifugal force during polishing, 120 ° or more is preferable, and 135 ° or more is more preferable. However, when the angle 122 increases, the upper part of the light transmission region 12 is worn by polishing or dressing (shaping process), and the area where the upper part of the light transmission region 12 contacts the object to be polished increases early. This causes an increase in scratches on the object to be polished. Therefore, the angle 122 is preferably 179.5 ° or less and more preferably 179 ° or less from the viewpoint of suppressing the occurrence of scratches on the object to be polished.

  The surface of the light transmission region 12 on the polishing region 13 side preferably has a water repellent layer from the viewpoint of efficiently discharging the slurry. The material constituting the water repellent layer is not particularly limited as long as it is a substance having water repellency, and examples thereof include fluorine-containing compounds and silicon-containing compounds. Examples of the fluorine-containing compound include compounds having a perfluoroalkyl group or a perfluoroalkylene ether group. Examples of the silicon-containing compound include compounds having a silicone skeleton.

  The arithmetic average roughness (Ra) of the surface of the light transmission region 12 on the polishing region 13 side is preferably 3 μm or less and more preferably 1 μm or less from the viewpoint of efficiently discharging the slurry. When the light transmission region 12 has a water repellent layer on the surface on the polishing region 13 side, the arithmetic average roughness (Ra) of the surface of the water repellent layer is preferably 3 μm or less from the viewpoint of efficiently discharging the slurry, 1 μm or less is more preferable.

  The surface of the light transmission region 12 opposite to the polishing region 13 is preferably flush with the surface of the polishing layer 11 opposite to the polishing region 13 from the viewpoint of preventing slurry leakage. A double-sided tape may be provided on the opposite side of the polishing layer 11 to the polishing region 13 in order to bond the polishing layer 11 to a platen, cushion layer, or the like. Since the surface of the polishing layer 11 is flush with the surface of the polishing layer 11 opposite to the polishing region 13, the polishing layer 11 and the light transmission region 12 can be bonded with a double-sided tape, which is preferable from the viewpoint of productivity.

  The material for forming the light transmission region 12 is not particularly limited. However, a material that can detect an optical end point with high accuracy while polishing and has a light transmittance of 10% or more in the entire wavelength range of 400 to 800 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, Acrylic resins, polycarbonate resins, halogen resins (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resins (polyethylene, polypropylene, etc.), thermoplastic resins, butadiene rubber, isoprene rubber, etc. Examples thereof include rubber, photo-curing resin that is cured by light such as ultraviolet rays and electron beams, and photosensitive resin. These resins may be used alone or in combination of two or more.

  The material for forming the light transmission region 12 is preferably the same as the material for forming the polishing region 13 or a material similar to the physical properties of the polishing region 13. In particular, it is preferable to use a polyurethane resin.

  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, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, Examples include p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and isophorone diisocyanate. . These may be used alone or in combination of two or more.

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

  In addition to the high molecular weight polyols described above as polyols, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1, Low molecular weight polyols such as 4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and 1,4-bis (2-hydroxyethoxy) benzene may be used in combination.

  Chain extenders include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3 -Low molecular weight polyols such as methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, or 2,4-toluenediamine, 2,6-toluenediamine, 3,5-diethyl-2,4-toluenediamine, 4,4′-di-sec-butyl-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 2,2 ′, 3,3′-tetrachloro-4,4′-diamino Phenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4,4'-methylene-bis-methyl Anthranilate, 4,4'-methylene-bis-anthranilic acid, 4,4'-diaminodiphenylsulfone, N, N'-di-sec-butyl-p-phenylenediamine, 4,4'-methylene- Bis (3-chloro-2,6-diethylaniline), 4,4′-methylenebis (o-chloroaniline), 3,3′-dichloro-4,4′-diamino-5,5′-diethyldiphenylmethane, 1 , 2-bis (2-aminophenylthio) ethane, trimethylene glycol di-p-aminobenzoate, 3,5-bis (methylthio) -2,4- Polyamines exemplified by toluenediamine and the like can be mentioned. These may be used alone or in combination of two or more. However, since the polyamines are often colored themselves or resins formed using these are colored in many cases, it is preferable to blend them so as not to impair the physical properties and light transmittance. In addition, when a compound having an aromatic hydrocarbon group is used, the light transmittance on the short wavelength side tends to be lowered. Therefore, it is particularly preferable not to use such a compound. In addition, a compound in which an electron donating group such as a halogen group or a thio group or an electron withdrawing group is bonded to an aromatic ring or the like tends to decrease the light transmittance. Therefore, such a compound may not be used. Particularly preferred. However, you may mix | blend to such an extent that the light transmittance requested | required by the short wavelength side is not impaired.

  The ratio of the isocyanate component, the polyol component, and the chain extender in the polyurethane resin can be appropriately changed depending on the molecular weight of each and the desired physical properties of the light transmission region produced therefrom. The number of isocyanate groups of the organic isocyanate relative to the total number of functional groups (hydroxyl group + amino group) of the polyol and the chain extender is preferably 0.90 to 1.15, more preferably 0.95 to 1.10. The polyurethane resin can be manufactured by applying a known urethanization technique such as a melting method or a solution method, but it is preferable to manufacture the polyurethane resin by a melting method in consideration of cost, working environment, and the like.

  As the polymerization procedure of the polyurethane resin, either a prepolymer method or a one-shot method is possible. From the viewpoint of stability and transparency of the polyurethane resin during polishing, an isocyanate-terminated prepolymer from an organic isocyanate and a polyol in advance. Is preferably synthesized, and a prepolymer method in which a chain extender is reacted with this is preferred. Moreover, it is preferable that the NCO weight% of the said prepolymer is about 2 to 12 weight%, More preferably, it is about 3 to 11 weight%. If the NCO wt% is less than 2 wt%, the reaction curing tends to take too much time and the productivity tends to decrease. On the other hand, if the NCO wt% exceeds 12 wt%, the reaction rate becomes too fast. As a result, air entrainment or the like occurs, and physical properties such as transparency and light transmittance of the polyurethane resin tend to deteriorate. When there are bubbles in the light transmission region, the attenuation of the reflected light increases due to light scattering, and the polishing end point detection accuracy and the film thickness measurement accuracy tend to decrease. Therefore, in order to remove such bubbles and make the light transmission region non-foamed, it is preferable to sufficiently remove the gas contained in the material by reducing the pressure to 10 Torr or less before mixing the material. . Moreover, in the stirring process after mixing, in the case of the stirring blade type mixer normally used, it is preferable to stir at the rotation speed of 100 rpm or less so that bubbles may not mix. In addition, the stirring step is preferably performed under reduced pressure. Furthermore, since the rotation and revolution type mixer is difficult to mix bubbles even at high rotation, it is also preferable to perform stirring and defoaming using the mixer.

  The production method of the light transmission region 12 is not particularly limited, and can be produced by a known method. For example, a polyurethane resin block produced by the above method can be made to have a predetermined thickness using a band saw type or canna type slicer, a method of pouring the resin into a mold having a cavity of a predetermined thickness, a coating technique, A method using a sheet forming technique is used.

  The Asker D hardness of the light transmission region 12 is preferably 30 to 80 degrees, and more preferably 30 to 75 degrees. By using the light transmission region having the hardness, deformation of the light transmission region can be suppressed.

  Examples of the material for forming the polishing region 13 include polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, halogen-based resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, and olefin-based materials. Examples thereof include resins (polyethylene, polypropylene, etc.), epoxy resins, and photosensitive resins. These may be used alone or in combination of two or more. The material for forming the polishing region may be the same or different from that of the light transmission region, but it is preferable to use the same type of material as that used for the light transmission region.

  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.

  The isocyanate component to be used is not particularly limited, and examples thereof include the isocyanate component.

  The high molecular weight polyol to be used is not particularly limited, and examples thereof include the high molecular weight polyol. In addition, the number average molecular weight of these high molecular weight polyols is not particularly limited, but is preferably 500 to 2000 from the viewpoint of the elastic characteristics of the obtained polyurethane. If the number average molecular weight is less than 500, a polyurethane using the number average molecular weight does not have sufficient elastic properties and becomes a brittle polymer. For this reason, the polishing region produced from this polyurethane 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 2,000, polyurethane using this is too soft, and the polishing region produced from this polyurethane tends to have poor planarization characteristics.

  Moreover, as a polyol, the said low molecular weight polyol can also be used together besides a high molecular weight polyol.

  As chain extenders, 4,4′-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline), 3, 5-bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene- 2,6-diamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 1,2-bis (2-aminophenylthio) ethane, 4,4′-diamino- 3,3′-diethyl-5,5′-dimethyldiphenylmethane, N, N′-di-sec-butyl-4,4′-diaminodiphenylmethane, 4, '-Diamino-3,3'-diethyldiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diisopropyl-5 5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetraethyldiphenylmethane, 4,4'-diamino-3,3', 5,5'-tetraisopropyldiphenylmethane, m-xyl Examples include polyamines exemplified by range amine, N, N′-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and p-xylylenediamine, or the low molecular weight polyol component described above. it can. 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 in the polyurethane resin can be variously changed depending on the molecular weight of each and the desired physical properties of the polishing region produced therefrom. In order to obtain a polishing region having excellent polishing characteristics, the number of isocyanate groups in the isocyanate component relative to the total number of functional groups (hydroxyl group + amino group) of the polyol component and the chain extender is preferably 0.95 to 1.15. Preferably it is 0.99 to 1.10.

  The polyurethane resin can be produced by the same method as described above. In addition, stabilizers such as antioxidants, surfactants, lubricants, pigments, solid beads, fillers such as water-soluble particles and emulsion particles, antistatic agents, abrasive grains, and other materials as necessary. Additives may be added.

  The polishing layer 11 is preferably a fine foam. By using a fine foam, the slurry can be held in the fine pores on the surface, and the polishing rate can be increased.

  The method of finely foaming the polyurethane resin is not particularly limited, and examples thereof include a method of adding hollow beads, a method of foaming by a mechanical foaming method, a chemical foaming method, and the like. In addition, although each method may be used together, the mechanical foaming method using the silicone type surfactant which is a copolymer of polyalkylsiloxane and polyether is especially preferable. Examples of the silicone surfactant include SH-192, L-5340 (manufactured by Toray Dow Corning Silicon), and the like.

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

  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. The use of air that has been dried to remove moisture is most preferable in terms of cost.

  As a stirring device for making non-reactive gas into fine bubbles and dispersing it in an isocyanate-terminated prepolymer containing a silicone-based surfactant, a known stirring device can be used without particular limitation. Specifically, a homogenizer, a dissolver, A two-axis planetary mixer (planetary mixer) is exemplified. The shape of the stirring blade of the stirring device is not particularly limited, but it is preferable to use a whipper-type stirring blade because fine bubbles can be obtained.

  In addition, it is also a preferable aspect to use a different stirring apparatus for the stirring which produces a bubble dispersion liquid in the stirring 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 stirring step and the mixing step, and it is also preferable to adjust the stirring conditions such as adjusting the rotation speed of the stirring blade as necessary. .

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

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

  The polyurethane foam may be produced by a batch method in which each component is metered into a container and stirred, and each component and a non-reactive gas are continuously supplied to the stirring device and stirred to produce bubbles. It may be a continuous production method in which a dispersion is sent out to produce a molded product.

  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 (flatness) of the object to be polished (wafer) after polishing tends to decrease.

  The specific gravity of the polyurethane foam is preferably 0.5 to 1.3. When the specific gravity is less than 0.5, the surface strength of the polishing region decreases, and the planarity of the object to be polished tends to decrease. On the other hand, when the ratio is larger than 1.3, the number of bubbles on the surface of the polishing region decreases, and planarity is good, but the polishing rate tends to decrease.

  The hardness of the polyurethane foam is preferably 45 to 70 degrees as measured by an Asker D hardness meter. When the Asker D hardness is less than 45 degrees, the planarity of the object to be polished is lowered. When the Asker D hardness is more than 70 degrees, the planarity is good, but the uniformity of the object to be polished is uniform. It tends to decrease.

  The polishing region 13 is manufactured by cutting the polyurethane foam prepared as described above into a predetermined size.

  The polishing region 13 is preferably provided with a groove for efficiently holding and renewing the slurry on the surface in contact with the object to be polished. The groove is not particularly limited as long as it is a surface shape that holds and renews the slurry. For example, XY lattice grooves, concentric circular grooves, through holes, non-through holes, polygonal columns, cylinders, spiral grooves, Examples include eccentric circular grooves, radial grooves, and combinations of these grooves. Further, the groove pitch, groove width, groove depth and the like are not particularly limited and are appropriately selected and formed. In addition, these grooves are generally regular, but the groove pitch, groove width, groove depth, etc. may be changed for each range to make the slurry retention and renewability desirable. Is possible.

  In the case where the polishing region 13 has a groove, it is preferable that the recess amount t of the portion of the light transmission region 12 through which the optical beam of the optical detection means is transmitted is larger than the depth d of the groove. Due to the abrasion of the polishing region 13 during the polishing operation of the object to be polished and the dressing operation (shaping operation) of the polishing region 13, the dent of the surface of the light transmission region 12 gradually decreases, but the amount of dent t on the surface of the light transmission region 12 Is larger than the depth d of the groove in the polishing region 13, so that the structure in which the transmission part of the beam in the light transmission region is recessed from the polishing region 13 can be maintained until the groove in the polishing region is eliminated. It is possible to extend the life of the polishing pad 10 while maintaining high.

  The thickness of the polishing layer 11 is not particularly limited, but is about 0.8 to 4.0 mm. As the method for producing the polishing layer 11 having the above thickness, a method in which the block of the fine foam is made to have a predetermined thickness using a band saw type or canna type slicer, or a resin is poured into a mold having a cavity having a predetermined thickness. Examples thereof include a curing method and a method using a coating technique or a sheet molding technique.

  The means for forming the opening 14 is not particularly limited, and examples thereof include a method of pressing or grinding with a cutting tool, a method of using a laser using a carbonic acid laser, and the like.

  The polishing pad 10 may be composed of only the polishing layer 11 having the polishing region 13 and the light transmission region 12, a laminate of the polishing layer 11 and another layer (for example, a cushion layer), and the It may consist of the light transmission region 12.

  The cushion layer supplements the characteristics of the polishing layer 11. The cushion layer 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 material having fine irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire material to be polished. The planarity is improved by the characteristics of the polishing layer 11, and the uniformity is improved by the characteristics of the cushion layer. In the polishing pad 10, the cushion layer is preferably softer than the polishing layer 11.

  Examples of the cushion layer 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 means for attaching the polishing layer 11 and the cushion layer include a method of pressing the polishing layer 11 and the cushion layer 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 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. In addition, since the polishing layer 11 and the cushion layer 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 10 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 10, it is preferable to use a film as 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.

<Second Embodiment>
A polishing pad 20 according to a second embodiment will be described with reference to FIGS. In addition, about the structure similar to the structure of the polishing pad 10 of 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  FIG. 7 is a schematic view showing an example of the polishing pad 20 of the present embodiment. As shown in FIG. 7, the polishing pad 20 includes a polishing layer 11 and a light transmission region 22. The light transmission region 22 is provided in the opening 14 of the polishing layer 11.

  FIG. 8 is a schematic cross-sectional view of the polishing pad 20 shown in FIG. 7 cut in the AB direction. As shown in FIG. 8, the light transmission region 22 is provided in an opening 14 that penetrates the polishing layer 11, and the center side of the polishing pad 20 on the surface of the light transmission region 22 on the polishing region 13 side is The surface of the polishing region 13 is recessed.

  FIG. 9 is an enlarged schematic view of the vicinity of the light transmission region 22 in the schematic cross-sectional view of the polishing pad 20 shown in FIG. As shown in FIG. 9, the end 225 on the center side of the polishing pad 20 on the surface of the light transmission region 22 on the polishing region 13 side is in contact with the wall surface 141 of the opening 14.

  The surface of the light transmission region 22 on the polishing region 13 side is a parallel portion 223 that is substantially parallel to the polishing region 13 from the end 225 toward the outer periphery of the polishing pad 20, and the polishing pad 20. It has a sloped portion 224 that is higher on the outer peripheral side. The gradient portion 224 is closer to the outer peripheral side of the polishing pad 20 than the parallel portion 223. The polishing pad 20 can reduce refraction and scattering of the light beam by transmitting the light beam of the optical detection means through the parallel part 223 by the light transmission region 22 having the parallel part 223. Therefore, it is possible to suppress a decrease in optical end point detection accuracy. Further, the polishing pad 20 has the light transmission region 22 having the inclined portion 224 on the outer peripheral side of the polishing pad 20 with respect to the parallel portion 223, so that the slurry is efficiently discharged from the concave portion by centrifugal force during polishing. And the generation of scratches on the object to be polished can be suppressed. That is, according to the polishing pad 20 of the present embodiment, it is possible to suppress the occurrence of scratches on the object to be polished while suppressing a decrease in optical end point detection accuracy.

  As shown in FIG. 9, the end 226 on the outer peripheral side of the polishing pad 20 on the surface of the light transmission region 22 on the polishing region 13 side of the light transmission region 22 is continuous with the end of the polishing region 13. Is in contact with As shown in FIG. 9, the end 226 may be in contact with the end of the polishing region 13, or may be in contact with the outer peripheral wall surface 142 of the polishing pad 20 of the opening 14. Although it is good, from the viewpoint of efficiently discharging the slurry by centrifugal force during polishing, the end 226 is preferably in contact with the end of the polishing region 13.

  In FIG. 9, the end 226 of the light transmission region 22 is in contact with the end of the polishing region 13 in a state having a gradient, but the end 226 of the light transmission region 22 is in contact with the polishing. It may be in contact with the end of the polishing region 13 in a state having the same plane as the region 13.

  The gradient 221 that is an angle between the inclined portion 224 and the plane including the parallel portion 223 can be appropriately changed depending on the thickness of the polishing layer 11 and the size of the light transmission region 12, but the centrifugal force during polishing may be changed. From the viewpoint of efficiently discharging the slurry, it is preferably 60 ° or less, and more preferably 45 ° or less. However, when the gradient 221 is reduced, the amount of depression h of the parallel portion 223 of the light transmission region 22 is reduced. When the dent amount h is small, when the polishing region 13 and the upper part of the light transmission region 12 are worn by polishing or dressing process (shaping process), the area where the upper part of the light transmission region 12 contacts the object to be polished is early. This increases the scratch on the object to be polished. Therefore, the angle 221 is preferably 0.5 ° or more, and more preferably 1 ° or more, from the viewpoint of suppressing generation of scratches on the object to be polished.

  The angle 222 between the outer peripheral side of the polishing pad 20 on the surface of the light transmission region 22 on the polishing region 13 side and the plane including the polishing region 13 depends on the thickness of the polishing layer 11 and the size of the light transmission region 22. Although it can change suitably, from a viewpoint of discharging | emitting a slurry efficiently with centrifugal force during grinding | polishing, 120 degrees or more are preferable and 135 degrees or more are more preferable. However, when the angle 222 is increased, the upper portion of the light transmission region 22 is worn by polishing or dressing processing (shaping processing), and the area where the upper portion of the light transmission region 22 is in contact with the object to be polished increases early. This causes an increase in scratches on the object to be polished. Therefore, the angle 222 is preferably 179.5 ° or less, and more preferably 179 ° or less from the viewpoint of suppressing generation of scratches on the object to be polished.

  The surface of the light transmission region 22 on the polishing region 13 side preferably has a water-repellent layer, like the polishing pad of the first embodiment, from the viewpoint of efficiently discharging the slurry.

  The arithmetic average roughness (Ra) of the surface of the light transmission region 22 on the polishing region 13 side is preferably 3 μm or less from the viewpoint of efficiently discharging the slurry, similarly to the polishing pad of the first embodiment. Is more preferable.

  Similar to the polishing pad of the first embodiment, the surface of the light transmission region 22 opposite to the polishing region 13 is flush with the surface of the polishing layer 11 opposite to the polishing region 13 from the viewpoint of preventing slurry leakage. It is preferable that

  Examples of the formation material and the production method of the light transmission region 22 are the same as the formation material and the production method of the light transmission region 12.

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

  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 and evaluation method>
[Arithmetic mean roughness of surface (Ra)]
In accordance with JIS B0601-1994, the arithmetic average roughness of the surface of the light transmission region on the polishing region side was measured.

[Evaluation of polishing characteristics]
[Polishing conditions]
Using MIRRA (Applied Materials) as a polishing apparatus, polishing was performed while dressing the surface of the polishing pad under the following conditions.
Monitor wafer (for defect evaluation): A thermal oxide film of 2000 mm, Ta100 mm, TaN100 mm, and Cu-seed 800 mm are deposited in this order on an 8-inch silicon wafer, and Cu plating 25000 mm is formed thereon.
Monitor wafer (for end point detection error): 8-inch pattern wafer (manufactured by SEMATEC, 854 pattern wafer)
-Slurry: PL7101 (Fujimi Incorporated) added with 1% by weight of hydrogen peroxide.
・ Slurry supply flow rate: 200 ml / min
Polishing load: 2 psi Retainer load: 2.6 psi
・ Rotation speed: Polishing / wafer = 70/70 rpm
-Dresser: DK45 (4-in dresser) 60 rpm manufactured by SAESOL

[Defect evaluation]
After polishing under the above-mentioned conditions, the wafer is cleaned with an alkali cleaning solution (manufactured by Sanyo Kasei Kogyo Co., Ltd., Jaspen) using a wafer cleaning apparatus (MAT-ZAB-8W2MC, manufactured by MAT), and the cleaned wafer is subjected to a surface defect inspection apparatus ( The number of striations of 0.24 μm or more on a Cu film in an EE (EDEGE-Exclusion) 5 mm region was measured using Surfscan SP1-TBI (manufactured by KLA Tencor).

[End point detection error]
When polishing the Cu film by polishing under the aforementioned conditions, the end point was detected using the end point detection function of the polishing apparatus. When the Cu film remains when the end point is detected or when the end point is not detected, the end point detection error is determined.

<Example 1>
[Production of light transmission region]
Using thermoplastic polyurethane A1098A (manufactured by Toyobo Co., Ltd.) and milactone E567 (manufactured by Nippon Polyurethane Co., Ltd.), a light transmission region 30 having a size that fits the opening of the polishing layer (diameter direction 56 mm × circumferential direction 20 mm) by injection molding. Was made. FIG. 10 is a schematic cross-sectional view of the light transmission region 30. In FIG. 10, D1 is 4.08 °, H1 is 4 mm, and W1 is 56 mm.

[Preparation of polishing layer]
In a reaction container, 100 parts by weight of a polyether-based prepolymer (manufactured by Uniroyal, Adiprene L-325, NCO wt%: 9.15 wt%), and a silicone surfactant (manufactured by Toray Dow Corning Silicone, SH -192) 3 parts by weight were mixed and the temperature was 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 amine, manufactured by Ihara Chemical Co.) previously melted at 120 ° C. was added thereto. Thereafter, stirring was continued for about 1 minute, and the reaction solution was poured into a pan-shaped open mold. When the fluidity of this reaction solution disappeared, it was put in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane foam block. This polyurethane foam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane foam sheet (average cell diameter 50 μm, specific gravity 0.86, D hardness 55 degrees). Next, this sheet was subjected to surface buffing to a predetermined thickness using a buffing machine (manufactured by Amitech Co., Ltd.) to obtain a sheet with adjusted thickness accuracy (thickness: 4.0 mm). This buffed sheet is punched out to a diameter of 61 cm, and a concentric groove having a groove width of 0.40 mm, a groove pitch of 3.1 mm, and a groove depth of 1.50 mm is used on the surface using a groove processing machine (manufactured by Toho Koki Co., Ltd.). Processing was performed. Using a laminator on the surface opposite to the grooved surface of this sheet, a double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape, thickness: 0.10 mm) is bonded to form a polishing layer 11 with double-sided tape. Produced.

[Production of polishing pad]
A cushion layer 40 made of polyethylene foam (Toray Industries, Toraypef, thickness: 1.27 mm) buffed and corona-treated is bonded to the adhesive surface of the produced double-sided tape-coated polishing layer using a laminator. A polishing sheet was prepared. Next, an opening having a size of 56 mm in diameter direction and 20 mm in the circumferential direction was formed in the polishing sheet. And the transparent support film 50 (base material: polyethylene terephthalate, thickness: 50 micrometers) which has an adhesive bond layer on both surfaces was bonded together to the cushion layer of the polishing sheet, and the laminated body was obtained. Then, the light transmission area | region 30 was affixed on the transparent support film in the opening part of this laminated body, and the polishing pad 100 was produced. FIG. 11 is a schematic cross-sectional view illustrating the configuration of the polishing pad 100 according to the first embodiment.

<Example 2>
[Production of light transmission region]
A light transmission region 31 was produced in the same manner as the light transmission region 30 except that the shape was changed. FIG. 12 is a schematic cross-sectional view of the light transmission region 31. In FIG. 12, D2 is 3.58 °, H2 is 4 mm, H3 is 0.5 mm, and W2 is 56 mm.

[Preparation of polishing layer]
The same operation as in Example 1 was performed.

[Production of polishing pad]
A polishing pad 101 was produced in the same manner as in Example 1 except that the light transmission region 31 was used instead of the light transmission region 30. FIG. 13 is a schematic cross-sectional view illustrating the configuration of the polishing pad 101 according to the second embodiment.

<Example 3>
[Production of light transmission region]
A light transmission region 32 was produced in the same manner as the light transmission region 30 except that the shape was changed. FIG. 14 is a schematic cross-sectional view of the light transmission region 32. In FIG. 14, D3 is 7.12 °, H4 is 4 mm, H5 is 1.5 mm, and W3 is 56 mm.

[Preparation of polishing layer]
The same operation as in Example 1 was performed.

[Production of polishing pad]
A polishing pad 102 was produced in the same manner as in Example 1 except that the light transmission region 32 was used instead of the light transmission region 30. FIG. 15 is a schematic cross-sectional view illustrating the configuration of the polishing pad 102 according to the third embodiment.

<Comparative Example 1>
[Production of light transmission region]
A light transmission region 33 was produced in the same manner as the light transmission region 30 except that the shape was changed. FIG. 16 is a schematic cross-sectional view of the light transmission region 33. In FIG. 16, H6 is 4 mm and W4 is 56 mm.

[Preparation of polishing layer]
The same operation as in Example 1 was performed.

[Production of polishing pad]
A polishing pad 103 was produced in the same manner as in Example 1 except that the light transmission region 33 was used instead of the light transmission region 30. FIG. 17 is a schematic cross-sectional view showing the configuration of the polishing pad 103 according to the first comparative example.

<Comparative example 2>
[Production of light transmission region]
A light transmission region 34 was produced in the same manner as the light transmission region 30 except that the shape was changed. FIG. 18 is a schematic cross-sectional view of the light transmission region 34. In FIG. 18, H4 is 1.5 mm and W3 is 56 mm.

[Preparation of polishing layer]
The same operation as in Example 1 was performed.

[Production of polishing pad]
A polishing pad 104 was produced in the same manner as in Example 1 except that the light transmission region 34 was used instead of the light transmission region 30. FIG. 19 is a schematic cross-sectional view illustrating the configuration of the polishing pad 104 according to the third embodiment.

  The polishing pads of Examples 1 to 3 did not generate end point detection errors even when polished for a long time. Further, defects such as particles and scratches were not observed on the wafers polished with the polishing pads of Examples 1 to 3.

  The method for producing a laminated polishing pad of the present invention requires high surface flatness such as optical materials such as lenses and reflecting mirrors, silicon wafers, glass substrates for hard disks, aluminum substrates, and general metal polishing processes. It can be used in a method for manufacturing a polishing pad that performs planarization of a material.

1, 10, 20, 100, 101, 102, 103, 104: Polishing pad 2: Polishing surface plate 3: Abrasive (slurry)
4: Material to be polished (semiconductor wafer)
5: Support base (polishing head)
6, 7: Rotating shaft 11: Polishing layers 12, 22, 30, 31, 32, 33, 34: Light transmission region 13: Polishing region 14: Openings 121, 221, D1, D2, D3: Gradient of the light transmission region 122, 222: Angles 124 between the surface of the light transmission region on the polishing region side and a plane including the polishing region 124, 225: Ends 125 of the light transmission region on the center side, 226: Polishing pad of the light transmission region End portion 141 on the outer peripheral side of the outer surface of the polishing pad 142: Wall surface 142 on the center side of the polishing pad in the opening portion: Wall surface 223 on the outer peripheral side of the polishing pad in the opening portion: Flat portion 224 in the light transmission region: Gradient portion 40 in the light transmission region 50: Transparent support film having adhesive layers on both sides

Claims (6)

A polishing pad having a polishing region and a light transmission region,
The surface of the light transmission region has a gradient such that the center side of the polishing pad is recessed from the surface of the polishing region, and the outer peripheral side becomes higher from the center side of the polishing pad toward the outer peripheral side. , Polishing pad.   The polishing pad according to claim 1, wherein an angle of the gradient is 60 ° or less.   The light transmission region has a portion substantially parallel to the polishing region on the center side of the polishing pad, and is arranged on the outer peripheral side of the polishing pad from the center side to the outer peripheral side of the polishing pad. The polishing pad according to claim 1, wherein the polishing pad has a gradient that becomes higher.   The polishing pad according to any one of claims 1 to 3, wherein an arithmetic average roughness (Ra) of a surface of the light transmission region on a polishing region side is 3 µm or less.   The polishing pad according to claim 1, further comprising a water repellent layer on a surface of the light transmission region. A method for manufacturing a semiconductor device, comprising a step of polishing a surface of a semiconductor wafer using the polishing pad according to claim 1.

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