JP2006190826A - Polishing pad and method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad which detects an optical end point at high accuracy during polishing, and prevents slurry from leaking between a polishing area and a light transmission region even if the pad is used for a long use, and to provide a method of manufacturing a semiconductor device using the polishing pad. <P>SOLUTION: The pad 1 comprises a polishing layer 11 having openings A10 for providing a polishing region 9 and a light transmission region 8 and a cushion layer 12 having an opening B13 smaller than the transmission region 8, laminated on the polishing layer 11 with the openings A10, B13 superposed one another. The light transmission region 8 locates above the opening B13 and in the opening A10. It comprises a water-impermeable elastic member 15 having lower hardness than those of the polishing region 9 and the light transmission region 8 in an annular groove 14 between the opening A10 and the transmission region 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polishing pad used when planarizing irregularities on a wafer surface by chemical mechanical polishing (CMP), and more specifically, a polishing pad having a window for detecting a polishing state or the like by optical means, and The present invention relates to 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 a polishing end point by irradiating a wafer with a light beam through a window (light transmission region) through a polishing pad and monitoring an interference signal generated by the reflection. Is the method.

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

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

  For example, a polishing pad having at least a part of a transparent polymer sheet that transmits solid and homogeneous light having a wavelength of 190 nm to 3500 nm is disclosed (Patent Document 3). Further, a polishing pad in which a stepped transparent plug is inserted is disclosed (Patent Document 4). Also, a polishing pad having a transparent plug that is the same surface as the polishing surface is disclosed (Patent Document 5). However, the polishing pad in which the transparent plug is inserted has a problem that the polishing characteristics such as in-plane uniformity of the wafer are deteriorated as compared with the polishing pad in which the transparent plug is not provided.

  On the other hand, proposals (Patent Documents 6 and 7) have been made to prevent the slurry from leaking from the boundary (seam) between the polishing region and the light transmission region. However, even when these transparent leakage prevention sheets are provided, the slurry leaks from the boundary (seam) between the polishing region and the light transmission region to the lower part of the polishing layer, and the slurry accumulates on the leakage prevention sheet to cause an optical end point. Problems with detection.

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

  The present invention has been made in order to solve the above problems, and enables high-precision optical end point detection in a state where polishing is being performed, is difficult to be deformed during polishing, and is used when used for a long time. Another object of the present invention is to provide a polishing pad capable of preventing slurry leakage from between the polishing region and the light transmission region, and to provide a method of manufacturing a semiconductor device using the polishing pad.

  As a result of intensive studies in view of the above-described present situation, the present inventor has found that the above-described problem can be solved by providing a water-impermeable elastic member in the gap between the polishing region and the light transmission region.

  That is, according to the present invention, the polishing layer, the polishing layer having the opening A for providing the light transmission region, and the cushion layer having the opening B smaller than the light transmission region are formed by the opening A and the opening B. Are laminated so that they overlap each other, a light transmission region is provided on the opening B and in the opening A, and further, in an annular groove between the opening A and the light transmission region. Further, the present invention relates to a polishing pad provided with a water-impermeable elastic member having a lower hardness than the polishing region and the light transmission region.

  A conventional polishing pad in which a light transmission region is inserted is fitted so that a gap is not generated as much as possible in the opening of the polishing region in order to prevent slurry leakage. However, it is considered that the slurry flows on the surface of the polishing pad during polishing, and the polishing region and the light transmission region are swollen by the solvent in the slurry. Then, due to the swelling of the polishing region and the light transmission region, the light transmission region and the fitting portion are distorted so that the light transmission region protrudes or the polishing pad is deformed. As a result, it is considered that polishing characteristics such as in-plane uniformity are deteriorated.

  In CMP, a polishing pad and an object to be polished such as a wafer rotate and revolve together, and polishing is performed by friction under pressure. During polishing, various forces (particularly in the horizontal direction) are acting on the light transmission region and the polishing region, so that a peeling state always occurs at the boundary between both members. It is considered that the conventional polishing pad is easily peeled off at the boundary between the two members, and a gap is generated at the boundary to cause slurry leakage. This slurry leakage is considered to cause optical problems such as fogging in the light end point detection unit, thereby reducing or disabling the end point detection accuracy.

  On the other hand, the polishing pad of the present invention has a water-impermeable elastic member having a hardness smaller than that of the polishing region and the light transmission region in the annular groove between the opening A and the light transmission region. Since the water-permeable elastic member has elasticity and has a sufficiently small hardness, it can absorb distortion and dimensional change generated in the light transmission region and the fitting portion. Therefore, the light transmission region does not protrude or deform during polishing or the polishing pad is not deformed, and deterioration of polishing characteristics such as in-plane uniformity can be suppressed.

  Further, the water-impermeable elastic member completely seals each contact portion of the polishing region, the light transmission region, and the cushion layer, and even when a force to peel off the light transmission region and the polishing region is applied during polishing. It has enough resistance to withstand it. Therefore, peeling hardly occurs at each contact portion, slurry leakage can be effectively prevented, and highly accurate optical end point detection is possible.

  The impermeable elastic member preferably has an Asker A hardness of 80 degrees or less, more preferably 60 degrees or less. When the Asker A hardness exceeds 80 degrees, the distortion and dimensional change generated in the light transmission region and the inset portion cannot be sufficiently absorbed, and the light transmission region protrudes or deforms during polishing. Tends to be easily deformed.

  The impermeable elastic member is preferably composed of an impermeable resin composition containing at least one impermeable resin selected from the group consisting of rubber, thermoplastic elastomer, and reaction curable resin.

  By using the above material, the water-impermeable elastic member can be easily formed, and the above-described effect becomes more excellent.

  The impermeable elastic member is preferably lower in height than the annular groove. If the height of the water-impermeable elastic member is equal to or higher than that of the annular groove, it will protrude from the pad surface during polishing, which may cause scratches and deteriorate polishing characteristics such as in-plane uniformity. It is in.

  In the present invention, the material for forming the light transmission region is preferably a non-foamed material. If it is a non-foamed material, light scattering can be suppressed, so that an accurate reflectance can be detected and the detection accuracy of the polishing optical end point can be increased.

  The Asker D hardness of the light transmission region is preferably 30 to 75 degrees. By using the light transmission region having the hardness, the generation of scratches on the wafer surface can be suppressed. In addition, it is possible to suppress the occurrence of scratches on the surface of the light transmission region, thereby enabling highly accurate optical end point detection to be performed stably. When Asker D hardness is less than 30 degrees, the abrasive grains in the slurry are likely to pierce the surface of the light transmission region, and scratches are easily generated on the silicone wafer by the pierced abrasive grains. Moreover, since it becomes easy to deform | transform, polishing characteristics, such as in-plane uniformity, fall, or it becomes easy to generate | occur | produce a slurry leak. On the other hand, when the Asker D hardness exceeds 75 degrees, the light transmission region is too hard, and the silicon wafer is likely to be scratched. Further, since the surface of the light transmission region is easily scratched, the transparency is lowered and the optical end point detection accuracy of polishing tends to be lowered.

  Further, it is preferable that the polishing surface of the light transmission region does not have a concavo-convex structure that holds and renews the polishing liquid. If there is macroscopic surface irregularities on the polishing side surface of the light transmission region, slurry containing additives such as abrasive grains accumulates in the recesses, and light scattering / absorption tends to affect detection accuracy. Further, it is preferable that the other surface side surface of the light transmission region does not have macro surface unevenness. This is because if there are macro surface irregularities, light scattering is likely to occur, which may affect detection accuracy.

  In the present invention, the forming material of the polishing region is preferably a fine foam. Moreover, it is preferable that the groove | channel is provided in the grinding | polishing side surface of the said grinding | polishing area | region.

  The average cell diameter of the fine foam is preferably 70 μm or less, more preferably 50 μm or less. If the average bubble diameter is 70 μm or less, planarity (flatness) is good.

  Moreover, it is preferable that the specific gravity of the said fine foam is 0.5-1.0, More preferably, it is 0.7-0.9. When the specific gravity is less than 0.5, the strength of the surface of the polishing region decreases, and the planarity of the object to be polished decreases. When it exceeds 1.0, the number of fine bubbles on the surface of the polishing region decreases. Therefore, the planarity is good, but the polishing rate tends to be small.

  Moreover, it is preferable that the hardness of the said fine foam is 45 to 85 degree | times by Asker D hardness, More preferably, it is 45 to 65 degree | times. When the Asker D hardness is less than 45 degrees, the planarity of the object to be polished is reduced. When the Asker D hardness is greater than 85 degrees, the planarity is good, but the uniformity of the object to be polished is decreased. Tend to.

  Moreover, it is preferable that the compression rate of the said fine foam is 0.5 to 5.0%, More preferably, it is 0.5 to 3.0%. If the compression ratio is within the above range, both planarity and uniformity can be sufficiently achieved. The compression rate is a value calculated by the following formula.

Compression rate (%) = {(T1-T2) / T1} × 100
T1: Thickness of the fine foam when a stress load of 30 kPa (300 g / cm ² ) is maintained for 60 seconds from an unloaded state to the fine foam.
T2: The thickness of the fine foam when a stress load of 180 kPa (1800 g / cm ² ) is maintained for 60 seconds from the state of T1.

  Moreover, it is preferable that the compression recovery rate of the said fine foam is 50 to 100%, More preferably, it is 60 to 100%. When it is less than 50%, as the repeated load is applied to the polishing region during polishing, a large change appears in the thickness of the polishing region, and the stability of the polishing characteristics tends to decrease. The compression recovery rate is a value calculated by the following formula.

Compression recovery rate (%) = {(T3-T2) / (T1-T2)} × 100
T1: Thickness of the fine foam when a stress load of 30 kPa (300 g / cm ² ) is maintained for 60 seconds from an unloaded state to the fine foam.
T2: The thickness of the fine foam when a stress load of 180 kPa (1800 g / cm ² ) is maintained for 60 seconds from the state of T1.
T3: The thickness of the fine foam when it is held for 60 seconds in a no-load state from the state of T2, and then a load of 30 kPa (300 g / cm ² ) stress is held for 60 seconds.

  Moreover, it is preferable that the storage elastic modulus in 40 degreeC and 1 Hz of the said fine foam is 200 Mpa or more, More preferably, it is 250 Mpa or more. When the storage elastic modulus is less than 200 MPa, the strength of the surface of the polishing region decreases, and the planarity of the object to be polished tends to decrease. The storage elastic modulus is an elastic modulus measured by applying a sinusoidal vibration to a fine foam using a dynamic viscoelasticity measuring device and using a tensile test jig.

  The present invention includes a step of laminating a cushion layer on a polishing layer having a polishing region and an opening A for providing a light transmission region, removing a part of the cushion layer in the opening A, and applying light to the cushion layer. A step of forming an opening B smaller than the transmission region, a step of providing a light transmission region on the opening B and in the opening A, and an annular groove between the opening A and the light transmission region Further, the present invention relates to a method for manufacturing the polishing pad, which includes a step of forming a water-impermeable elastic member by injecting and curing a water-impermeable resin composition.

  The present invention also provides a polishing layer having a polishing region, an opening A for providing a light transmission region, and a cushion layer having an opening B smaller than the light transmission region. In the annular groove between the opening A and the light transmission region, the step of providing a light transmission region on the opening B and in the opening A, It is related with the manufacturing method of the said polishing pad including the process of forming a water-impermeable elastic member by inject | pouring and hardening a resin composition.

  The present invention also relates to a method for manufacturing a semiconductor device including a step of polishing a surface of a semiconductor wafer using the polishing pad described above.

  The polishing pad of the present invention has at least a polishing region, a light transmission region, a cushion layer, and a water-impermeable elastic member.

  The material for forming the light transmission region is not particularly limited, but it is preferable to use a material having a light transmittance of 50% or more in the entire region having a wavelength of 400 to 700 nm. Examples of such materials include polyurethane resins, polyester resins, polyamide resins, acrylic resins, polycarbonate resins, halogen resins (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resins (polyethylene). And polypropylene), and epoxy resins. These may be used alone or in combination of two or more. It is preferable to use a material similar to the forming material used for the polishing region and the physical properties of the polishing region. In particular, a highly abrasion-resistant polyurethane resin that can suppress light scattering in the light transmission region due to dressing marks during polishing is desirable.

  The polyurethane resin is composed of organic isocyanate, polyol (high molecular weight polyol or low molecular weight polyol), chain extender and the like.

  Examples of the organic isocyanate include 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, isophorone diisocyanate, and the like. . These may be used alone or in combination of two or more.

  As the organic isocyanate, in addition to the diisocyanate compound, a trifunctional or higher polyfunctional polyisocyanate compound can also be used. 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.). These trifunctional or higher functional polyisocyanate compounds are preferably used by adding to the diisocyanate compound because they are easily gelled during prepolymer synthesis when used alone.

  Examples of the high molecular weight polyol include polyester polyols represented by polytetramethylene ether glycol, polyester polyols represented by polybutylene adipate, polycaprolactone polyol, and polycaprolactone. A polyester polycarbonate polyol or an ethylene carbonate exemplified by a reaction product of glycol and alkylene carbonate is reacted with a polyhydric alcohol, and then the resulting reaction mixture is reacted. Examples thereof include polyester polycarbonate polyol reacted with an organic dicarboxylic acid, and polycarbonate polycarbonate obtained by transesterification of a polyhydroxyl compound with aryl carbonate. 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-methylanthra Nilate, 4,4′-methylene-bis-anthranilic acid, 4,4′-diaminodiphenylsulfone, N, N′-di-sec-butyl-p-phenylenediamine, 4,4′-methylene-bis ( 3-chloro-2,6-diethylamine), 3,3′-dichloro-4,4′-diamino-5,5′-diethyldiphenylmethane, 1,2-bis (2-aminophenylthio) ethane, trimethyleneglycol Polyamines exemplified by luge-p-aminobenzoate, 3,5-bis (methylthio) -2,4-toluenediamine and the like Can. These may be used alone or in combination of two or more.

  The ratio of the organic isocyanate, polyol, and 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 from these. In order to adjust the Asker D hardness of the light transmission region to 30 to 75 degrees, 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 0.9 to 1.2. It is preferable that it is 0.95 to 1.05.

  In order to adjust the Asker D hardness of the light transmission region to 30 to 75 degrees, a plasticizer may be added. A known plasticizer can be used without particular limitation. For example, phthalic acid diesters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di (2-ethylhexyl) phthalate, dinonyl phthalate, and dilauryl phthalate, dioctyl adipate, di (2-ethylhexyl) adipate, Aliphatic dibasic esters such as diisononyl adipate, dibutyl sebacate, dioctyl sebacate, and di (2-ethylhexyl) sebacate, tricresyl phosphate, tri (2-ethylhexyl) phosphate, and tri (2-ethylhexyl) phosphate Glycol esters such as chloropropyl), polyethylene glycol esters, ethylene glycol monobutyl ether acetate, and diethylene glycol monobutyl ether acetate, epoxidized soybean oil, and epoxy fatty acid ester And epoxy compounds such as ether and the like. In these, it is preferable to use the glycol ester type plasticizer which does not contain active hydrogen from a compatible viewpoint with a polyurethane resin and polishing slurry.

  The plasticizer is preferably added to the polyurethane resin so as to be in the range of 4 to 40% by weight. By adding the specific amount of the plasticizer, the Asker A hardness of the light transmission region can be easily adjusted within the above range. The addition amount of the plasticizer is more preferably 7 to 25% by weight in the polyurethane resin.

  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. In the case of the prepolymer method, the plasticizer is preferably added to the isocyanate-terminated prepolymer in order to uniformly disperse it in the polyurethane resin. Moreover, it is preferable that the NCO weight% of the said prepolymer is about 2 to 8 weight%, More preferably, it is about 3 to 7 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 8 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.

  The method for producing the light transmission region 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 shape of the light transmission region is not particularly limited, but is preferably the same shape as the opening A of the polishing region.

  The thickness of the light transmission region is not particularly limited, but is preferably equal to or less than the thickness of the polishing region. If the light transmission region is thicker than the polishing region, the silicon wafer may be damaged by the protruding portion during polishing. Further, the light transmission region is deformed by the stress applied during polishing, and is greatly distorted optically, so that there is a possibility that the optical end point detection accuracy of polishing is lowered.

  Further, the variation in the thickness of the light transmission region is preferably 100 μm or less, and more preferably 50 μm or less. When the thickness variation exceeds 100 μm, it has a large waviness and tends to affect the polishing characteristics because portions with different contact states with the wafer are generated.

  As a method of suppressing the variation in thickness, a method of buffing a sheet surface having a predetermined thickness can be mentioned. The buffing is preferably performed in stages using polishing sheets having different particle sizes. In addition, when buffing the light transmission region, the smaller the surface roughness, the better. When the surface roughness is large, the incident light is irregularly reflected on the surface of the light transmission region, so that the light transmittance is lowered and the detection accuracy tends to be lowered.

  The material for forming the polishing region can be used without particular limitation as long as it is normally used as the material for the polishing layer, but in the present invention, it is preferable to use a fine foam. For example, polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resin (polyethylene, polypropylene, etc.), epoxy resin And photosensitive resin. These may be used alone or in combination of two or more. The material for forming the polishing region may be the same composition as or different from 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 polyurethane resin is composed of an organic isocyanate, a polyol, and a chain extender.

  The organic isocyanate to be used is not particularly limited, and examples thereof include the organic isocyanates described above.

  The polyol to be used is not particularly limited, and examples thereof include the polyols described above. In addition, the number average molecular weight of these polyols is not particularly limited, but is preferably 500 to 2000 from the viewpoint of the elastic properties of the resulting 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. Therefore, the polishing pad manufactured from this polyurethane becomes too hard and causes scratches on the polishing surface of the object to be polished. Moreover, since it becomes easy to wear, it is not preferable from the viewpoint of the pad life. On the other hand, when the number average molecular weight exceeds 2000, polyurethane using the same becomes soft, so that a polishing pad produced from this polyurethane tends to have poor planarization characteristics.

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

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

  Examples of chain extenders include polyamines exemplified by 4,4′-methylenebis (o-chloroaniline), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline) and the like. Or the low molecular weight polyols mentioned above. These may be used alone or in combination of two or more.

  The ratio of the organic isocyanate, polyol, and 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 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 0.95 to 1.15, and more preferably Is 0.99 to 1.10.

  The polyurethane resin can be produced by the same method as described above. If necessary, stabilizers such as antioxidants, surfactants, lubricants, pigments, fillers, antistatic agents, and other additives may be added to the polyurethane resin.

  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 and does not have an active hydrogen group is preferable. Examples of the silicone surfactant include SH-192 (manufactured by Toray Dow Corning Silicone) and the like as a suitable compound.

An example of a method for producing a closed cell type polyurethane foam used in the polishing region will be described below. The manufacturing method of this polyurethane foam has the following processes.
1) Stirring step for producing a cell dispersion of isocyanate-terminated prepolymer Add a silicone surfactant to the isocyanate-terminated prepolymer, stir with a non-reactive gas, and disperse the non-reactive gas as fine bubbles to disperse the bubble. Use liquid. When the isocyanate-terminated prepolymer is solid at room temperature, it is preheated to an appropriate temperature and melted before use.
2) Curing Agent (Chain Extender) Mixing Step A chain extender is added to the above cell dispersion and mixed and stirred.
3) Curing step An isocyanate-terminated prepolymer mixed with a chain extender is cast and cured by heating.

  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 method for producing the polyurethane fine foam, heating and post-curing the foam that has reacted until the foam dispersion does not flow by pouring the cell dispersion into the mold has the effect of improving the physical properties of the foam, Very suitable. The bubble dispersion may be poured into the mold and immediately placed in a heating oven for post-cure. Under such conditions, heat is not immediately transferred to the reaction components, so the bubble diameter 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 tertiary amine or organotin may be used. The type and addition 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 can be produced in a batch system in which each component is weighed into a container and stirred. Alternatively, each component and a non-reactive gas are continuously supplied to a stirrer 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 polishing area to be the polishing layer is manufactured by cutting the polyurethane foam prepared as described above into a predetermined size.

  It is preferable that the polishing area | region which consists of a fine foam is provided with the groove | channel for hold | maintaining and renewing a slurry in the grinding | polishing side surface which contacts a to-be-polished object. Since the polishing region is formed of a fine foam, it has a large number of openings on the polishing surface and has a function of holding the slurry. However, in order to efficiently further maintain the slurry and renew the slurry. In order to prevent destruction of the object to be polished due to adsorption with the object to be polished, it is preferable to have a groove on the surface on the polishing side. 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.

  The method of forming the groove 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 pouring and curing a resin in a mold having a predetermined surface shape , A method of pressing a resin with a press plate having a predetermined surface shape, a method of forming using photolithography, a method of forming using a printing technique, and a laser beam using a carbon dioxide gas laser, etc. The method of doing is mentioned.

  Although the thickness of a grinding | polishing area | region is not specifically limited, It is about 0.8-2.0 mm. As a method of producing the polishing region of the thickness, a method of making the block of the fine foam a predetermined thickness using a band saw type or a canna type slicer, pouring resin into a mold having a cavity of a predetermined thickness, and curing And a method using a coating technique or a sheet forming technique.

  Further, the variation in the thickness of the polishing region is preferably 100 μm or less, and particularly preferably 50 μm or less. When the variation in thickness exceeds 100 μm, the polishing region has a large undulation, and there are portions where the contact state with the object to be polished is different, which tends to adversely affect the polishing characteristics. In order to eliminate the variation in the thickness of the polishing region, the surface of the polishing region is generally dressed with a dresser in which diamond abrasive grains are electrodeposited or fused in the initial stage of polishing, but the above range is exceeded. Things will increase dressing time and reduce production efficiency. In addition, as a method for suppressing the variation in thickness, there is also a method of buffing the surface of the polishing region having a predetermined thickness. When buffing, it is preferable to carry out stepwise with abrasive sheets having different particle sizes.

  The material for forming the water-impermeable elastic member is not particularly limited as long as it can impart water resistance and elasticity and has a hardness lower than that of the polishing region and the light transmission region. For example, rubber, thermoplastic elastomer, or reaction Examples thereof include a composition (pressure-sensitive adhesive or adhesive) containing an impermeable resin such as a curable resin.

  Rubbers include natural rubber, silicone rubber, acrylic rubber, urethane rubber, butadiene rubber, chloroprene rubber, isoprene rubber, nitrile rubber, epichlorohydrin rubber, butyl rubber, fluorine rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, and styrene-butadiene. For example, rubber. Among these, it is preferable to use silicone rubber, acrylic rubber, or urethane rubber.

  As thermoplastic elastomer (TPE), natural rubber TPE, polyurethane TPE, polyester TPE, polyamide TPE, fluorine TPE, polyolefin TPE, polyvinyl chloride TPE, styrene TPE, styrene-butadiene-styrene block Copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-isoprene-styrene block copolymer (SIS).

  The reaction curable resin is a thermosetting, photocurable, or moisture curable resin, and examples thereof include silicone resins, elastic epoxy resins, (meth) acrylic resins, and urethane resins. Among these, it is preferable to use a silicone resin, an elastic epoxy resin, or a urethane resin.

  In order to adjust the elasticity and hardness of the water-impermeable elastic member, a plasticizer and a crosslinking agent can be appropriately added to the water-impermeable resin composition. Examples of the crosslinking agent include silane compounds, polyisocyanate compounds, epoxy compounds, aziridine compounds, melamine resins, urea resins, anhydrous compounds, polyamines, and carboxyl group-containing polymers. Moreover, when using a photocurable resin, it is preferable to add a photoinitiator. Further, in addition to the above components, additives such as various conventionally known tackifiers, anti-aging agents, fillers, anti-aging agents, catalysts and the like can be contained as necessary.

  The method for producing the polishing pad of the present invention is not particularly limited, and various methods can be considered. Specific examples will be described below.

  FIG. 2 is a schematic configuration diagram showing an example of the polishing pad of the present invention.

  As a first specific example, first, a cushion layer 12 is bonded to a polishing layer 11 having a polishing region 9 and an opening A (10) for providing a light transmission region 8. Next, a part of the cushion layer in the opening A is removed, and an opening B (13) smaller than the light transmission region is formed in the cushion layer. Next, a light transmission region is fitted on the opening B and in the opening A. Then, the water-impermeable elastic member 15 is injected by injecting the water-impermeable resin composition into the annular groove 14 in the gap between the opening A and the light-transmitting region and cured by heating, light irradiation, moisture, or the like. Form.

  As a second specific example, first, a polishing layer 11 having a polishing region 9 and an opening A (10) for providing a light transmission region 8, and an opening B (13) smaller than the light transmission region are provided. The cushion layer 12 is pasted so that the opening A and the opening B overlap. Next, a light transmission region is fitted on the opening B and in the opening A. Then, the water-impermeable elastic member 15 is injected by injecting the water-impermeable resin composition into the annular groove 14 in the gap between the opening A and the light-transmitting region and cured by heating, light irradiation, moisture, or the like. Form.

  In the method for creating the polishing pad, the means for opening the polishing region and the cushion layer is not particularly limited. For example, a method of pressing and opening a jig having cutting ability, a laser using a carbonic acid laser or the like. Examples thereof include a method of using and a method of grinding with a jig such as a cutting tool. The size and shape of the opening A are not particularly limited.

  The width of the annular groove between the opening A and the light transmission region is not particularly limited, but in consideration of injecting the water-impermeable resin composition into the groove, the proportion of the light transmission region in the polishing pad, and the like. The thickness is preferably about 0.5 to 3 mm, more preferably 1 to 2 mm. When the groove width is less than 0.5 mm, it becomes difficult to inject the water-impermeable resin composition into the groove. In addition, since the distortion and dimensional change generated in the light transmission region and the inset portion cannot be sufficiently absorbed, the light transmission region protrudes during polishing, or the polishing pad deforms and polishing characteristics such as in-plane uniformity. Tend to get worse. On the other hand, when the groove width exceeds 3 mm, the ratio of the portion that does not contribute to polishing in the polishing pad increases, which is not preferable.

  The cushion layer supplements the characteristics of the polishing region (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 an object to be polished having minute irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire object to be polished. The planarity is improved by the characteristics of the polishing layer, and the uniformity is improved by the characteristics of the cushion layer. In the polishing pad of the present invention, the cushion layer is preferably softer than the polishing layer.

  A material for forming the cushion layer is not particularly limited. For example, 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 such as polyurethane foam and polyethylene foam Examples thereof include rubber resins such as foam, butadiene rubber and isoprene rubber, and photosensitive resins.

  Examples of means for attaching the polishing layer and the cushion layer include a method in which the polishing region and the cushion layer are sandwiched between the double-sided tapes 16 and pressed.

  The double-sided tape 16 has a general configuration in which adhesive layers are provided on both sides of a base material such as a nonwoven fabric or a film. 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 composition of the polishing region and the cushion layer may be different, the composition of each adhesive layer of the double-sided tape can be made different so that the adhesive force of each layer can be optimized.

  On the other surface side of the cushion layer, a double-sided tape 16 for bonding to the platen may be provided. Examples of means for attaching the cushion layer and the double-sided tape include a method of pressing and bonding the double-sided tape to the cushion layer.

  The double-sided tape has a general configuration in which an adhesive layer is provided on both surfaces of a base material such as a nonwoven fabric or a film as described above. In consideration of peeling from the platen after using the polishing pad, it is preferable to use a film as the base material because the tape residue and the like can be eliminated. The composition of the adhesive layer is the same as described above.

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

  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.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. The evaluation items in Examples and the like were measured as follows.

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

(Asker D hardness measurement)
This was performed in accordance with JIS K6253-1997. A water-impermeable elastic member, light transmissive region, or polished region cut into a size of 2 cm × 2 cm (thickness: arbitrary) is used as a hardness measurement sample in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. It was allowed to stand for 16 hours. At the time of measurement, the samples were overlapped to a thickness of 6 mm or more. The hardness was measured using a hardness meter (manufactured by Kobunshi Keiki Co., Ltd., Asker D type hardness meter).

(Average bubble diameter measurement)
A polishing region cut in parallel with a microtome cutter as thin as possible to a thickness of about 1 mm was used as a sample for measuring average bubble diameter. The sample was fixed on a slide glass, and using an image processing apparatus (Image Analyzer V10, manufactured by Toyobo Co., Ltd.), the total bubble diameter in an arbitrary 0.2 mm × 0.2 mm range was measured, and the average bubble diameter was calculated. .

(Specific gravity measurement)
This was performed according to JIS Z8807-1976. A polished area cut into a 4 cm × 8.5 cm strip (thickness: arbitrary) was used as a sample for measuring specific gravity, and the sample was allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. The specific gravity was measured using a hydrometer (manufactured by Sartorius).

(Measurement of compression rate and compression recovery rate)
A polishing area (polishing layer) cut into a 7 mm diameter circle (thickness: arbitrary) is used as a sample for measuring the compression rate and compression recovery rate, and left for 40 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. did. For the measurement, a thermal analysis measuring instrument TMA (manufactured by SEIKO INSTRUMENTS, SS6000) was used to measure the compression rate and the compression recovery rate. The calculation formulas for compression ratio and compression recovery ratio are shown below.

Compression rate (%) = {(T1-T2) / T1} × 100
T1: The thickness of the polishing layer when a load of 30 kPa (300 g / cm ² ) of stress is maintained for 60 seconds from the unloaded state on the polishing layer.
T2: Polishing layer thickness when a stress load of 180 kPa (1800 g / cm ² ) is maintained for 60 seconds from the state of T1.

Compression recovery rate (%) = {(T3-T2) / (T1-T2)} × 100
T1: The thickness of the polishing layer when a load of 30 kPa (300 g / cm ² ) of stress is maintained for 60 seconds from the unloaded state on the polishing layer.
T2: Polishing layer thickness when a stress load of 180 kPa (1800 g / cm ² ) is maintained for 60 seconds from the state of T1.
T3: Thickness of the polishing layer when held for 60 seconds in a no-load state from the state of T2 and then holding a stress load of 30 kPa (300 g / cm ² ) for 60 seconds.

(Storage elastic modulus measurement)
This was performed in accordance with JIS K7198-1991. A polishing region cut into a 3 mm × 40 mm strip (thickness: arbitrary) was used as a sample for dynamic viscoelasticity measurement, and the sample was allowed to stand in a container containing silica gel for 4 days under an environmental condition of 23 ° C. The accurate width and thickness of each sheet after cutting was measured with a micrometer. For measurement, a storage elastic modulus E ′ was measured using a dynamic viscoelastic spectrometer (manufactured by Iwamoto Seisakusho, present IS Engineering Co., Ltd.). The measurement conditions at that time are shown below.
<Measurement conditions>
Measurement temperature: 40 ° C
Applied strain: 0.03%
Initial load: 20g
Frequency: 1Hz

(Water leakage 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 continuously for 30 minutes, and then the inset portion of the light transmission region on the back side of the polishing pad was visually observed, 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 Microelectronics) was added as an alkaline slurry at a flow rate of 150 ml / min during polishing, a polishing load of 350 g / cm ² , a polishing plate rotation speed of 35 rpm, and a wafer rotation speed. 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.
○: Slurry leakage at the inset portion is not recognized at all.
X: Slurry leakage at the inset portion is observed.

(Evaluation of deformation of light transmission region)
The wafer was polished by the same method as described above. Thereafter, the surface of the light transmission region was observed, and the deformation of the light transmission region was evaluated according to the following criteria. The evaluation results are shown in Table 1. It should be noted that the non-uniform dress scratches on the surface of the light transmission region indicate that the light transmission region is easily deformed during polishing.
○: Dress scratches are evenly attached to the surface of the light transmission region.
X: Dress scratches are unevenly formed on the surface of the light transmission region.

[Production of light transmission region]
A polyester polyol (number average molecular weight 2400) 128 parts by weight composed of adipic acid, hexanediol and ethylene glycol and 30 parts by weight of 1,4-butanediol were mixed, and the temperature was adjusted to 70 ° C. To this mixed solution, 100 parts by weight of 4,4′-diphenylmethane diisocyanate previously adjusted to 70 ° C. was added and stirred for about 1 minute. Then, the mixed solution was poured into a container kept at 100 ° C. and post-cured at 100 ° C. for 8 hours to produce a polyurethane resin. Using the produced polyurethane resin, a light transmission region (length 56 mm, width 20 mm, thickness 1.25 mm) was prepared by injection molding. The Asker D hardness of the produced light transmission region was 59 degrees.

[Production of polishing area]
Production Example 1
In a reaction vessel, 100 parts by weight of a polyether prepolymer (Uniroy Corporation, Adiprene L-325, NCO concentration: 2.22 meq / g), and a silicone nonionic surfactant (Toray Dow Silicone, SH192) ) 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 a rotation speed of 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 reaction solution lost its fluidity, it was put in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin foam block. This polyurethane resin foam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane resin foam sheet. Next, this sheet was subjected to surface buffing to a predetermined thickness using a buffing machine (Amitech Co., Ltd.) to obtain a sheet with adjusted thickness accuracy (sheet thickness: 1.27 mm). This buffed sheet is punched into a predetermined diameter (61 cm), and a groove processing machine (manufactured by Toho Steel Machine Co., Ltd.) is used to form a groove with a groove width of 0.25 mm, a groove pitch of 1.50 mm, and a groove depth of 0.40 mm. Concentric grooves were processed. Using a laminator on the surface opposite to the grooved surface of this sheet, a double-sided tape (Sekisui Chemical Co., Ltd., double tack tape) is applied, and then a light transmission area is formed at a predetermined position of the grooved sheet. An opening A (60 mm × 24 mm) for fitting was punched out to produce a polishing area with a double-sided tape. The physical properties of the produced polishing region were an average bubble diameter of 45 μm, a specific gravity of 0.86, an Asker D hardness of 53 degrees, a compression rate of 1.0%, a compression recovery rate of 65.0%, and a storage elastic modulus of 275 MPa.

Production Example 2
A polishing region with a double-sided tape was prepared in the same manner as in Production Example 1 except that the size of the opening A was 56 mm × 20 mm.

[Production of polishing pad]
Example 1
A cushioning layer made of polyethylene foam (Toray Industries, Toraypef, thickness: 0.8 mm) buffed and corona-treated is used on the adhesive surface of the polishing area with double-sided tape prepared in Production Example 1 using a laminator. And pasted together. Next, a double-sided tape was bonded to the cushion layer surface. And the cushion layer was punched out by the magnitude | size of 50 mm x 14 mm among the hole parts punched out in order to insert the light transmissive area | region, and the opening part B was formed. The produced light transmission region was fitted into the opening A (annular groove width: 2 mm). Then, a water-impermeable elastic member (height: 1 mm, Asker A hardness: 27 degrees (Asker) by injecting a silicone sealant (Cemedine, 8060) into the annular groove to a height of 1 mm and curing. A polishing pad was prepared by forming a D hardness of 4 degrees)).

Example 2
In Example 1, a polishing pad was prepared in the same manner as in Example 1 except that a urethane sealant (S-700M, manufactured by Cemedine) was used instead of the silicone sealant. The impermeable elastic member had an Asker A hardness of 32 degrees (Asker D hardness of 7 degrees).

Example 3
In Example 1, a polishing pad was prepared in the same manner as in Example 1 except that an elastic epoxy adhesive (PM210, manufactured by Cemedine) was used instead of the silicone sealant. The impermeable elastic member had an Asker A hardness of 58 degrees (Asker D hardness of 15 degrees).

Example 4
In Example 1, a polishing pad was produced in the same manner as in Example 1 except that the following urethane sealant was used instead of the silicone sealant. The impermeable elastic member had an Asker A hardness of 55 degrees (Asker D hardness of 14 degrees).

  Isocyanate prepolymer (L100 manufactured by Uniroyal Co., Ltd.) adjusted to 80 ° C. and 4,4′-di-sec-butyl-diaminodiphenylmethane (Unilink 4200) adjusted to 100 ° C. as a curing agent A urethane-based sealing agent was prepared by mixing so that the molar ratio of groups to amino groups was 1.05 / 1.0.

Example 5
In Example 1, a polishing pad was prepared in the same manner as in Example 1 except that the following photocurable resin composition was used instead of the silicone sealant and photocured by ultraviolet irradiation. The impermeable elastic member had Asker A hardness of 70 degrees (Asker D hardness of 26 degrees).

  100 parts by weight of urethane acrylate (manufactured by AKCROS CHEMICALS, Actilane 290) and 1 part by weight of benzyl dimethyl ketal are mixed and liquidized by stirring for about 3 minutes at a rotation speed of 800 rpm using a rotating and rotating mixer (manufactured by Sinky). A photocurable resin composition was prepared.

Comparative Example 1
A polishing pad was produced in the same manner as in Example 1 except that the impermeable elastic member was not provided in the annular groove.

Comparative Example 2
Using a laminating machine for the adhesive surface of the polishing area with double-sided tape produced in Production Example 2, a cushion layer made of polyethylene foam (Toray Industries, Toraypef, thickness: 0.8 mm) buffed and corona-treated And pasted together. Next, a double-sided tape was bonded to the cushion layer surface. And the cushion layer was punched out by the magnitude | size of 50 mm x 14 mm among the hole parts punched out in order to fit the light transmissive area | region of a grinding | polishing area | region, and the opening part B was formed. And the produced light transmission area | region was inserted in the opening part A, and the polishing pad was produced. Since the light transmission region and the opening A are the same size, there is no gap between the polishing region and the light transmission region.

Comparative Example 3
In Example 1, a polishing pad was produced in the same manner as in Example 1 except that the following urethane sealant was used instead of the silicone sealant. The Asker D hardness of the water-impermeable elastic member was 75 degrees.

  Isocyanate prepolymer adjusted to 80 ° C. (Uniroy Corporation, L325) and 4,4′-methylenebis (o-chloroaniline) adjusted to 120 ° C. as a curing agent (Ihara Chemical amine, Iharacamine MT ) Was mixed so that the molar ratio of isocyanate group to amino group was 1.05 / 1.0 to prepare a urethane-based sealing agent.

表１から明らかなように、研磨領域と光透過領域との間にある環状溝内に、研磨領域及び光透過領域よりも硬度の小さい不透水性弾性部材を設けることにより、光透過領域及びはめ込み部分に生じた歪みや寸法変化を吸収することができる。また、該不透水性弾性部材は、研磨領域と光透過領域とクッション層の各接触部分を完全にシールすることができるため、効果的にスラリー漏れを防止することができる。

As apparent from Table 1, by providing a water-impermeable elastic member having a hardness smaller than that of the polishing region and the light transmission region in the annular groove between the polishing region and the light transmission region, the light transmission region and the fitting are provided. It is possible to absorb distortion and dimensional change generated in the portion. Moreover, since the water-impermeable elastic member can completely seal each contact portion of the polishing region, the light transmission region, and the cushion layer, it is possible to effectively prevent slurry leakage.

Schematic configuration diagram showing an example of a conventional polishing apparatus used in CMP polishing Schematic sectional view showing an example of the polishing pad of the present invention Schematic configuration diagram showing an example of a CMP polishing apparatus having an end point detection apparatus of the present invention

Explanation of symbols

1: Polishing pad 2: Surface plate 3: Abrasive (slurry)
4: Object to be polished (wafer)
5: Object to be polished (wafer) support stand (polishing head)
6, 7: Rotating shaft 8: Light transmission region 9: Polishing region 10: Opening A
11: Polishing layer 12: Cushion layer 13: Opening B
14: annular groove 15: impermeable elastic member 16: double-sided tape 17: laser interferometer 18: laser beam

Claims (7)

A polishing layer having a polishing region and an opening A for providing a light transmission region, and a cushion layer having an opening B smaller than the light transmission region are laminated so that the opening A and the opening B overlap. A light transmission region is provided on the opening B and in the opening A, and a polishing region and a light transmission are provided in an annular groove between the opening A and the light transmission region. A polishing pad provided with an impermeable elastic member having a hardness lower than that of the region. The polishing pad according to claim 1, wherein the water-impermeable elastic member has an Asker A hardness of 80 degrees or less. The impermeable elastic member comprises an impermeable resin composition containing at least one impermeable resin selected from the group consisting of rubber, a thermoplastic elastomer, and a reaction curable resin. Polishing pad. The polishing pad according to claim 1, wherein the water-impermeable elastic member has a height lower than that of the annular groove. A step of laminating a cushion layer on a polishing layer having a polishing region and an opening A for providing a light transmission region; removing a part of the cushion layer in the opening A; A step of forming a small opening B, a step of providing a light transmission region on the opening B and in the opening A, and an impermeable water in an annular groove between the opening A and the light transmission region The manufacturing method of the polishing pad in any one of Claims 1-4 including the process of forming a water-impermeable elastic member by inject | pouring and hardening a permeable resin composition. A polishing layer having a polishing region and an opening A for providing a light transmission region, and a cushion layer having an opening B smaller than the light transmission region are laminated so that the opening A and the opening B overlap. Injecting the water-impermeable resin composition into the step, the step of providing a light transmission region on the opening B and in the opening A, and the annular groove between the opening A and the light transmission region The manufacturing method of the polishing pad in any one of Claims 1-4 including the process of forming a water-impermeable elastic member by making it harden | cure. 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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