JP5789523B2 - Polishing pad and chemical mechanical polishing method using the polishing pad - Google Patents

Description

  The present invention relates to a polishing pad containing a thermoplastic polyurethane nonwoven fabric and a chemical mechanical polishing method using the same.

  In order to improve the performance of semiconductor circuits, miniaturization of elements and wiring circuits having functions such as transistors and resistors, and higher wiring density by stacking are required. By increasing the density of such elements and wirings, it is possible to achieve high integration of elements and to realize a semiconductor circuit with excellent high-speed response.

  The accuracy of increasing the density of the semiconductor circuit depends on the accuracy of the photolithography process when forming the circuit pattern. A fine circuit pattern is formed by transferring a fine circuit pattern with high accuracy onto a semiconductor wafer by exposure through a resist mask in a photolithography process.

  In order to meet the demand for higher performance required for semiconductor circuits, the depth of focus of a projection lens used for photolithography becomes shallower as the circuit pattern becomes finer. In this case, it is required that the irregularities on the surface of the semiconductor wafer be within the focal depth of the projection lens. Therefore, as the circuit pattern becomes finer, the demand for flatness required on the surface of the semiconductor wafer increases.

  Chemical mechanical polishing (CMP) is widely used as a polishing technique that gives high flatness to the surface of a semiconductor wafer. CMP is a method of polishing by bringing a rotating polishing pad into contact while dripping polishing slurry onto the surface of a rotating substrate to be polished. By polishing the surface of the semiconductor wafer using CMP, a flat surface with irregularities controlled to the nanometer order can be obtained. By controlling the unevenness of the surface of the semiconductor wafer on the order of nanometers, high integration of elements and circuit stacking can be realized with high accuracy. CMP is not only polishing the surface of a semiconductor wafer, but also an interlayer insulating film, a PTEOS film (a silicon oxide film formed by plasma CVD using tetraethyl orthosilicate as a target and an oxidizing agent such as ozone), a BPSG film ( (Silicon oxide film doped with boron, phosphorus, etc.), shallow trench isolation, plugs, buried metal wiring, etc.

  As a polishing pad used for CMP, a polishing pad made of a nonwoven fabric impregnated with a polymer elastic body and a polishing pad made of polyurethane foam as disclosed in, for example, the following Patent Documents 1 to 4 Pads are known. Non-woven fabric type polishing pads have the advantages of being low in rigidity and flexible, so that they have excellent followability to the shape of the surface to be polished and are less likely to generate scratches. In addition, the retention of the polishing slurry is also excellent. However, due to its flexibility, there has been a problem that the polishing rate and flattening performance (uniformity of the flatness in the surface) on the surface to be polished is lower than that of a polishing pad made of polyurethane foam.

  The polyurethane foam is generally obtained by casting and molding a two-component curable polyurethane. Polyurethane foam is highly rigid and has a closed cell structure. Polyurethane is characterized by high hardness. A polishing pad made of polyurethane foam is produced by grinding or slicing polyurethane foam to an appropriate thickness.

  Polyurethane foam has higher rigidity than a non-woven fabric type polishing pad. Therefore, the polishing pad made of polyurethane foam has an advantage of high polishing rate and flattening performance. However, since the rigidity is high, the followability to the surface to be polished is low, and there is a drawback that scratches are easily generated because force is easily applied to the aggregate of abrasive grains of the polishing slurry.

  Polyurethane foam has a closed cell structure. For this reason, it is difficult for polishing slurry and polishing debris to penetrate deep into the interior, and the polishing pad after use is relatively easy to clean. However, since it has a closed cell structure, when the surface to be polished is continuously polished for a long time, agglomerates of polishing scraps and abrasive particles of polishing slurry accumulate in closed cells, which makes it easy to generate scratches. .

  Furthermore, since polyurethane has a high surface hardness, a polishing pad made of polyurethane foam has the advantages of excellent wear resistance and long life.

  As described above, a polishing pad made of polyurethane foam has advantages and disadvantages based on the properties of high rigidity, closed cells, and high hardness.

  By the way, conventionally, as disclosed in the following Patent Document 5 or Patent Document 6, a flexible and stretchable nonwoven fabric manufactured using a melt-spun thermoplastic polyurethane fiber is used as a medical clothing material or the like. It is known to be used for This is an application using a stretch characteristic and breathability of a nonwoven fabric made of thermoplastic polyurethane fibers but not allowing fine dust to pass therethrough.

JP 2000-178374 A JP 2000-248034 A JP 2001-89548 A Japanese Patent Laid-Open No. 11-322878 JP 08-113861 A Japanese Patent Laid-Open No. 03-76856

"CMP Science" Science Forum, Inc., August 20, 1997

  In order to increase the CMP polishing rate, it is important that the polishing pad has a high hardness, as described in Non-Patent Document 1. Since the two-component curable polyurethane forming the polyurethane foam is formed by a two-component chemical reaction, the reaction could not be allowed to proceed completely in a short time. Therefore, it has been difficult to form a polyurethane foam having a sufficiently high hardness. Further, as described above, since it has a closed cell structure, agglomerates of polishing scraps and abrasive grains of the polishing slurry accumulate in closed cells, and there is a drawback that scratches are likely to occur. Furthermore, it is difficult to control the rigidity of the polyurethane foam in a wide range, and it is difficult to improve the followability of the substrate to be polished with respect to the surface to be polished.

  In order to solve the above-described problems, the present invention provides a polishing pad in which the generation of scratches is suppressed, and a high polishing rate and high polishing uniformity can be realized by controlling the rigidity in a wide range. The purpose is to do.

One aspect of the present invention (except those containing the impregnated elastic polymer) nonwoven fabric having an average diameter 10~50μm of fibers storage modulus of a thermoplastic polyurethane is 150~900MPa at 80 ° C. or A polishing pad comprising: According to such a configuration, since the polishing pad has communication holes derived from the gaps between the fibers forming the nonwoven fabric, agglomerates of abrasive particles of polishing waste and polishing slurry are quickly discharged. Generation of scratches on the surface to be polished can be suppressed. In addition, since the polishing pad is made of a nonwoven fabric, the level of rigidity can be widely controlled by adjusting the fiber density by, for example, heat pressing. And the thermoplastic polyurethane whose storage elastic modulus in 80 degreeC is 150-900 Mpa, since rigidity becomes moderate, it is excellent in a polishing rate and planarization performance, and followability is also moderate.

  The porosity of the polishing pad is preferably in the range of 1 to 50%. By adjusting the porosity to such a range, a polishing pad having high rigidity can be obtained.

  In addition, when the storage elastic modulus of thermoplastic polyurethane at 110 ° C. is 40 MPa or less, even when the temperature rises due to friction between the polishing pad and the surface to be polished, the followability of the polishing pad can be sufficiently maintained. Scratches are less likely to occur on the surface to be polished.

  The thermoplastic polyurethane is obtained by melt polymerization of a polymer diol, an organic diisocyanate, and a chain extender. In this case, the polymer diol is polytetramethylene glycol, in particular, the number average molecular weight is 1200 to 1200. In the case of containing 4000 to 100% by mass of 4000 polytetramethylene glycol, it is preferable because the storage elastic modulus becomes more appropriate.

  Another aspect of the present invention is a method for chemical mechanical polishing of a substrate, wherein the polishing slurry is dropped on one of the polishing pads or the surface of the substrate while the polishing slurry is dropped on the surface of the polishing pad. This is a chemical mechanical polishing method in which the surface of the substrate is polished by relatively moving the substrate and the polishing pad in a state where the surface of the material is in pressure contact. According to such a polishing method, it is possible to realize high-flatness polishing at a high polishing rate while suppressing generation of scratches.

  According to the present invention, it is possible to provide a polishing pad that suppresses the occurrence of scratches and has a high polishing rate and high polishing uniformity.

FIG. 1 is a schematic view for explaining a chemical mechanical polishing method according to an embodiment of the present invention.

  An embodiment of a polishing pad containing a nonwoven fabric of thermoplastic polyurethane fibers according to the present invention will be described in detail.

  The polishing pad of this embodiment consists of a nonwoven fabric of thermoplastic polyurethane fibers having an average diameter of 10 to 50 μm. Such a nonwoven fabric can be controlled to a predetermined porosity by pressing. The thermoplastic polyurethane fiber is formed by melt spinning a previously polymerized thermoplastic polyurethane, as will be described later. For this reason, the surface hardness is higher than that of a polishing pad having a foam structure made of two-component curable polyurethane. In addition, since the nonwoven fabric has a communication hole structure, agglomerates of polishing dust and abrasive particles of polishing slurry are difficult to accumulate during CMP, and the generation of scratches is suppressed.

  The average diameter of the thermoplastic polyurethane fiber forming the nonwoven fabric is 10 to 50 μm, preferably 12 to 45 μm, and more preferably 15 to 42 μm. When the average diameter of the thermoplastic polyurethane fiber is less than 10 μm, the resulting polishing pad becomes too soft and the polishing rate and the flattening performance are lowered. In addition, if it exceeds 50 μm, the fibers are too thick and the stress tends to concentrate, and the gaps between the fibers on the surface are likely to be large, and it is easy to grip abrasive scraps and abrasive slurry aggregates. Thus, scratches are likely to occur on the surface to be polished. The average diameter of the thermoplastic polyurethane fiber is, for example, a cross section of the polishing pad taken with a scanning microscope (SEM) at a magnification of 500 times, and the diameter of 50 fibers uniformly selected from the obtained SEM photograph is measured. It is obtained by calculating the average value.

  Moreover, it is preferable that the porosity of the polishing pad which consists of a nonwoven fabric is 1-50%, 2-40%, especially 3-20%. The porosity is the ratio of the void to the apparent volume. When the porosity exceeds 50%, the polishing rate becomes low due to low rigidity, and when the porosity is too low, the volume of the communication hole decreases and the abrasive particles of polishing scraps and polishing slurry are reduced. There is a tendency that the effect of suppressing scratches on the surface to be polished is reduced due to the difficulty of discharging. The porosity is calculated, for example, by taking a cross section of the polishing pad with a SEM at a magnification of 200 times, binarizing the thermoplastic polyurethane fiber part and the void part by image processing from the obtained SEM photograph, and calculating the area ratio. Can do.

  First, the thermoplastic polyurethane forming the thermoplastic polyurethane fiber (hereinafter also simply referred to as “polyurethane”) will be described in detail. The production method of the polyurethane used in the present embodiment is not particularly limited. Specifically, for example, a polymer diol, an organic diisocyanate, and a chain extender are melt-mixed at a predetermined ratio, and substantially in the absence of a solvent. A melt polymerization method, a prepolymer method using a known urethanization reaction, or a one-shot method is used. Among these, a melt polymerization method is particularly preferably used from the viewpoint of production efficiency. The melt polymerization is a method in which a high molecular diol, an organic diisocyanate, a chain extender, and an additive that is blended as necessary are blended in a predetermined ratio and are continuously melt polymerized using a multi-screw extruder.

  The polymer diol, organic diisocyanate, and chain extender, which are raw materials for polyurethane polymerization, will be described in detail.

  Specific examples of the polymer diol include polyether diol, polyester diol, polycarbonate diol, and the like. These polymer diols may be used alone or in combination of two or more. Among these, it is preferable to use polyether diol, polyester diol, or a combination of polyether diol and polyester diol. The number average molecular weight of the polymer diol is preferably in the range of 1200 to 4000, more preferably 1300 to 3500. The number average molecular weight of the polymer diol can be calculated based on the hydroxyl value measured according to JIS K1557.

  Specific examples of the polyether diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (methyltetramethylene glycol), glycerin-based polyalkylene ether glycol, and the like. These may be used alone or in combination of two or more. Among these, it is preferable to use polyethylene glycol, polytetramethylene glycol, a combination of polyethylene glycol and polytetramethylene glycol, and mainly polytetramethylene glycol.

  Specific examples of the polyester diol include those obtained by direct esterification or transesterification of an ester-forming derivative such as dicarboxylic acid, its ester or anhydride, and a low molecular diol.

  Specific examples of the dicarboxylic acid used as the raw material for the polyester diol include, for example, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 2-methylsuccinic acid, 2 -C2-C12 such as methyl adipic acid, 3-methyl adipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, 3,7-dimethyldecanedioic acid Aliphatic dicarboxylic acid; fat such as dimerized aliphatic dicarboxylic acid having 14 to 48 carbon atoms (dimer acid) obtained by dimerization of unsaturated fatty acid obtained by fractional distillation of triglyceride or hydrogenated product thereof (hydrogenated dimer acid) Dicarboxylic acids; cycloaliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; terephthalic acid, isophthalic acid, ortho Aromatic dicarboxylic acids such as tall acid, and the like. These may be used alone or in combination of two or more. Examples of commercially available dimer acid or hydrogenated dimer acid include trade names “PRIPOL 1004”, “PRIPOL 1006”, “PRIPOL 1009”, and “PRIPOL 1013” manufactured by Unikema Corporation.

  Specific examples of the low molecular diol used as a raw material for the polyester diol include, for example, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, and 1,4-butane. Diol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1 , 8-octanediol, 1,9-nonanediol, 1,10-decanediol, and the like; and cycloaliphatic diols such as cyclohexanedimethanol and cyclohexanediol. These may be used alone or in combination of two or more. Among these, crystals after polymerization of diols having 6 to 12 carbon atoms, more preferably 8 to 10 carbon atoms, and particularly 9 carbon atoms such as 2-methyl-1,8-octanediol and 1,9-nonanediol. It is preferable from the point of being excellent in balance.

  Specific examples of the polycarbonate diol include those obtained by reacting a low-molecular diol with a carbonate compound such as dialkyl carbonate, alkylene carbonate, and diaryl carbonate. As the low molecular diol, the same low molecular diol as the raw material of the polyester diol can be used. Specific examples of the dialkyl carbonate include dimethyl carbonate and diethyl carbonate. Moreover, as a specific example of alkylene carbonate, ethylene carbonate etc. are mentioned, for example. Moreover, as a specific example of diaryl carbonate, diphenyl carbonate etc. are mentioned, for example.

  Among the above-mentioned polymer diols, in particular, polytetramethylene glycol, which is a polyether diol, is 30 to 100% by mass, more preferably 50 to 100% by mass, particularly 75 to 100% by mass, and in particular 85 to 85% by mass. A polymer diol containing 100% by mass is preferred. When such a polymer diol is used, the soft segment derived from the polyurethane polymer diol and the hard segment derived from the organic diisocyanate and the chain extender are phase-separated appropriately, and the storage elastic modulus is moderately increased. Become. When the ratio of polytetramethylene glycol in the polymer diol is too small, the soft segment and the hard segment are not sufficiently separated, and the storage elastic modulus at 80 ° C. tends to be small.

  The number average molecular weight of polytetramethylene glycol is 1200 to 4000, 1300 to 3500, particularly 1400 to 3000, and more preferably 1700 to 3000. When such polytetramethylene glycol is used, the soft segment derived from polytetramethylene glycol of polyurethane and the hard segment derived from organic diisocyanate and chain extender are phase-separated appropriately, resulting in a storage elastic modulus. Become more reasonable.

  Specific examples of the organic diisocyanate include, for example, ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate. , Isophorone diisocyanate, isopropylidenebis (4-cyclohexylisocyanate), cyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis (2-isocyanate) Natoethyl) fumarate, bis (2-isocyanatoethyl) carbonate Aliphatic, cycloaliphatic or alicyclic such as 2-isocyanatoethyl-2,6-diisocyanatohexanoate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexene Diisocyanate; 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4, '- diisocyanatodiphenylmethane, chloro-phenylene-2,4-diisocyanate, aromatic diisocyanates such as tetramethylxylylene diisocyanate, and the like. These may be used alone or in combination of two or more. Among these, 4,4'-diphenylmethane diisocyanate is preferable from the viewpoint that the abrasion resistance of the polishing pad obtained is high.

  The chain extender is not particularly limited as long as it is a chain extender conventionally used in the production of polyurethane, but has a molecular weight of 300 or less having two or more active hydrogen atoms capable of reacting with an isocyanate group in the molecule. Low molecular weight compounds are preferred. Specific examples of such chain extenders include, for example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,2- Butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5- Cyclohexanedimethanol such as pentanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bis (β-hydroxyethyl) terephthalate, 1,9-nonane Diols such as diol, m-xylylene glycol, p-xylylene glycol Class: ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylene Diamine, 2,4,4-trimethylhexamethylenediamine, 3-methylpentamethylenediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-diaminopropane, hydrazine, Xylylenediamine, isophoronediamine, piperazine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, tolylenediamine, xylenediamine, adipic acid di Dorazide, isophthalic acid dihydrazide, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 3,4'-diaminodiphenyl ether, 4,4 '-Diaminodiphenyl sulfone, 3,4-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-methylene-bis (2-chloroaniline), 3,3'-dimethyl-4,4'- Diaminobiphenyl, 4,4'-diaminodiphenyl sulfide, 2,6-diaminotoluene , 2,4-diaminochlorobenzene, 1,2-diaminoanthraquinone, 1,4-diaminoanthraquinone, 3,3'-diaminobenzophenone, 3,4-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'- Diaminobibenzyl, 2,2′-diamino-1,1′-binaphthalene, 1,3-bis (4-aminophenoxy) alkane, 1,4-bis (4-aminophenoxy) alkane, 1,5-bis ( 1, n-bis (4-aminophenoxy) alkane (n is 3 to 10), 1,2-bis [2- (4-aminophenoxy) ethoxy] ethane, 9,9- Examples include diamines such as bis (4-aminophenyl) fluorene and 4,4′-diaminobenzanilide. These may be used alone or in combination of two or more.

  Among chain extenders, a chain extender containing 50 mol% or more of 1,4-butanediol (BD) is preferable, and particularly a combination of BD and 3-methyl-1,5-pentanediol (MPD). The BD / MPD molar ratio is preferably 50/50 to 100/0, more preferably 55/45 to 95/5, and particularly preferably 60/40 to 90/10. When such a chain extender is used, it is preferable from the viewpoint that the storage elastic modulus at 80 ° C. and 110 ° C. becomes appropriate.

  The content of nitrogen atoms derived from isocyanate groups in the polyurethane is 4.6 to 6.2% by mass, more preferably 4.8 to 6.0% by mass, and particularly 5.0 to 5.8% by mass. It is preferable that the storage elastic modulus at 80 ° C. and 110 ° C. is moderate.

  The mixing ratio of the polymer diol, the organic diisocyanate, and the chain extender is appropriately adjusted according to the required physical properties. Specifically, for example, the isocyanate group contained in the organic diisocyanate is 0.95 to 1.3 mol, more preferably 0.96 to 1 with respect to 1 mol of active hydrogen atoms contained in the polymer diol and the chain extender. It is preferable to blend in a ratio of 10 mol, particularly 0.97 to 1.05 mol. When the ratio of isocyanate groups contained in the organic diisocyanate is too low, the mechanical strength and wear resistance of the resulting polyurethane are lowered, and the life of the polishing pad tends to be shortened. On the other hand, when the ratio of the isocyanate group contained in the organic diisocyanate is too high, the productivity and storage stability of polyurethane tend to decrease.

  The mass ratio of the polymer diol to the sum of the organic diisocyanate and the chain extender ([polymer diol] / [organic diisocyanate and chain extender]) is 15/85 to 45/55, more preferably 20/80. -40/60, in particular 25 / 75-35 / 65, in particular 27 / 73-35 / 65.

  Polyurethane is a crosslinking agent, filler, crosslinking accelerator, crosslinking aid, softener, tackifier, anti-aging agent, foaming agent, processing aid, adhesion promoter, inorganic filler, organic filler, crystal nucleating agent , Heat stabilizers, weather stabilizers, antistatic agents, colorants, lubricants, flame retardants, flame retardant aids (antimony oxide, etc.), blooming inhibitors, mold release agents, thickeners, antioxidants, conductive agents, etc. These additives may be contained as necessary. The content of the additive in the polyurethane is preferably 50% by mass or less, more preferably 20% by mass or less, and particularly preferably 5% by mass or less.

  As described above, the thermoplastic polyurethane is prepared by blending, for example, a polymer diol, an organic diisocyanate, a chain extender, and an additive blended as necessary at a predetermined ratio, and using a multi-screw extruder. The melted thermoplastic polyurethane strand obtained by continuous melt polymerization is cooled by water cooling and then pelletized to prepare a form that can be easily used for melt spinning.

  The intrinsic viscosity [η] of the thermoplastic polyurethane is preferably 0.5 to 1.5 dl / g. If the intrinsic viscosity [η] of the thermoplastic polyurethane is too low, melt spinnability tends to decrease and thinning tends to be difficult. Further, when the intrinsic viscosity [η] of the thermoplastic polyurethane is too high, the diameter tends to vary due to an increase in melt viscosity.

  Moreover, the storage elastic modulus at 80 ° C. of the thermoplastic polyurethane is 150 to 900 MPa, preferably 170 to 880 MPa, and more preferably 190 to 860 MPa. When the storage elastic modulus at 80 ° C. of the thermoplastic polyurethane is less than 150 MPa, the rigidity of the polishing pad becomes too low and the polishing rate and the flattening performance are lowered. On the other hand, when the storage elastic modulus at 80 ° C. of the thermoplastic polyurethane exceeds 900 MPa, the rigidity becomes too high and the followability to the surface to be polished decreases, thereby increasing the occurrence of scratches.

  Further, the storage elastic modulus of thermoplastic polyurethane at 110 ° C. is preferably 40 MPa or less, more preferably 36 MPa or less, and particularly preferably 34 MPa or less. If the storage modulus of thermoplastic polyurethane at 110 ° C. is too high, when the temperature rises due to friction between the polishing pad and the surface to be polished, the rigidity of the polishing pad is too high and scratches are generated on the surface to be polished. It tends to occur easily.

  And the nonwoven fabric which consists of a thermoplastic polyurethane fiber with an average diameter of 10-50 micrometers is obtained by using the manufacturing method of the nonwoven fabric provided with the melt spinning process like the spun bond method or the melt blown method for the above thermoplastic polyurethane. .

  In the spunbond method, for example, thermoplastic polyurethane is heated and melted and discharged from a spinneret, and the obtained spun yarn is cooled using a horizontal blowing type cooling device or an annular blowing type cooling device, After pulling and thinning using a suction device such as soccer or a take-up means such as a roller, the yarn group discharged from the suction device is opened. Then, the sheet is deposited on a moving deposition apparatus such as a conveyor made of a screen mesh. And the nonwoven fabric which consists of thermoplastic polyurethane fibers is obtained by performing a partial heat press to the sheet | seat on a movement deposition apparatus using partial thermocompression-bonding apparatuses, such as a heated embossing apparatus or an ultrasonic fusion apparatus. In addition, the rigidity of the nonwoven fabric obtained can be controlled by adjusting the fiber density and the porosity in the hot pressing step.

  In addition, the melt blown method is, for example, melted by heating and melting polyurethane and ejecting it from a discharge port of a spinning nozzle, and ejecting heated gas from gas outlets disposed on both sides across the discharge port. The polyurethane is made into fine fibers. Then, the finely divided polyurethane fibers are sprayed onto the moving net conveyor without substantially converging, and separated from the air current on the net conveyor to be deposited. The softened polyurethane fiber deposits are bonded to each other and cooled to obtain a web-like nonwoven fabric. In addition, while pressurizing the deposit using a pressure roller before cooling, or increasing the bonding strength by heating and pressurizing using a heating and pressure roller after cooling, adjusting the fiber density and porosity, The rigidity of the resulting nonwoven fabric can be controlled. As conditions for melt spinning in the melt blown method, it is preferable to set the nozzle temperature to about 220 to 280 ° C. so that the melt viscosity of polyurethane is 500 poises or less.

  The shape of the cross section which is a cross section perpendicular | vertical to the length direction of a thermoplastic polyurethane fiber is not specifically limited. Specifically, for example, in addition to a round cross section, a flat cross section, an elliptical cross section, a polygonal form, a leaf shape, a T shape, an H shape, a V shape, a dog bone (I shape), etc., a hollow cross section Etc.

  In this way, a nonwoven fabric of thermoplastic polyurethane fibers having an average diameter of 10 to 50 μm is obtained. And a polishing pad is obtained by processing the obtained nonwoven fabric into a desired dimension and shape by processes, such as cutting, slicing, and punching, as needed. In addition, the polishing pad thus obtained is further subjected to a grinding process for the purpose of spreading the polishing slurry more uniformly on the polishing surface and improving the discharging property of polishing debris. Concentric, spiral, and lattice grooves or holes may be formed by performing treatment or laser processing.

  Although the thickness of a polishing pad is not specifically limited, For example, about 0.3-5 mm is preferable from the stability of polishing performance and the point of productivity. Further, the polishing pad may be used as it is, or may be used in a state where a cushion layer of about 0.5 to 5 mm is laminated on the surface opposite to the polishing surface of the polishing pad.

  As the cushion layer, for example, a nonwoven fabric impregnated with polyurethane (for example, “Suba400” manufactured by Nitta Haas Co., Ltd.); rubber base materials such as natural rubber, nitrile rubber, polybutadiene rubber, and silicone rubber; polyester-based thermoplastic elastomer , Polyamide-based thermoplastic elastomer, fluorine-based thermoplastic elastomer and other thermoplastic elastomer substrates; foamed plastic substrates; polyurethane substrates, and the like. Among these, a polyurethane substrate is particularly preferable from the viewpoint of flexibility as a cushion layer. Such a cushion layer is bonded to the opposite surface of the polishing pad with a double-sided tape or the like.

  Next, CMP using the polishing pad of this embodiment will be described in detail with reference to FIG. FIG. 1 is a side view showing a state of the chemical mechanical polishing method using the polishing pad 10 of the present embodiment.

  In the CMP using the polishing pad 10 of the present embodiment, for example, a CMP apparatus 20 including a circular rotating surface plate 11, a slurry supply nozzle 12, a carrier 13, and a pad conditioner 14 as shown in FIG. Is used. A polishing pad 10 is affixed to the surface of the rotating surface plate 11 with a double-sided tape or a hook-and-loop fastener. The carrier 13 supports the substrate 15 to be polished.

  In the CMP apparatus 20, the rotating surface plate 11 is rotated in a direction indicated by an arrow by a motor (not shown). Further, the carrier 13 is rotated in a direction indicated by an arrow by a motor (not shown) within the surface of the rotating surface plate 11. The pad conditioner 14 is also rotated in the direction of the arrow, for example, by a motor (not shown) within the surface of the rotating surface plate 11.

  First, for CMP in which distilled water flows on the surface of the polishing pad 10 that is fixed to the rotating platen 11 and rotates, for example, diamond particles are fixed on the surface of the carrier by nickel electrodeposition or the like. The pad conditioner 14 is pressed to condition the surface of the polishing pad 10. The surface of the polishing pad is adjusted to a surface roughness suitable for polishing the surface to be polished by conditioning. Next, the polishing slurry 16 is supplied from the slurry supply nozzle 12 to the surface of the rotating polishing pad 10. The polishing slurry 16 is, for example, a liquid medium such as water or oil; an abrasive such as silica, alumina, cerium oxide, zirconium oxide, or silicon carbide; a base, an acid, a surfactant, an oxidizing agent, a reducing agent, a chelating agent, or the like. Contains. Moreover, when performing chemical mechanical polishing, you may use lubricating oil, a coolant, etc. together with polishing slurry as needed. Then, the substrate 15 to be polished, which is fixed to the carrier 13 and rotates, is pressed against the polishing pad 10 in which the polishing slurry 16 has spread evenly. Then, the polishing process is continued until a predetermined flatness is obtained. The quality of the finished product is affected by adjusting the pressing force applied during polishing and the speed of the relative movement between the rotating surface plate 11 and the carrier 13.

  The polishing conditions are not particularly limited, but for efficient polishing, the rotation speed of each of the surface plate and the substrate is preferably a low rotation of 300 rpm or less, and the pressure applied to the substrate is set so that no scratches are generated after polishing. In view of the above, it is preferably 150 kPa or less. During polishing, it is preferable to continuously supply the polishing slurry to the polishing pad with a pump or the like. The supply amount is not limited, but it is preferable that the surface of the polishing pad is always covered with the polishing slurry.

  Then, it is preferable that after the polishing is completed, the substrate to be polished is thoroughly washed with running water, and then water droplets attached to the substrate to be polished are removed by using a spin dryer or the like and dried. Thus, by polishing the surface to be polished with the polishing slurry, a smooth surface can be obtained over the entire surface to be polished.

  Such CMP of this embodiment can be used for polishing in manufacturing processes of various semiconductor devices, MEMS (Micro Electro Mechanical Systems), and the like. Examples of objects to be polished include, for example, a semiconductor wafer; an inorganic insulating film such as a silicon oxide film, a glass film, or a silicon nitride film formed on a wiring board having a predetermined wiring; polysilicon, aluminum, copper, titanium, titanium nitride , Films mainly containing tungsten, tantalum, tantalum nitride, etc .; optical glasses such as photomasks, lenses, prisms; inorganic conductive films such as tin-doped indium oxide (ITO); optical integrated circuits composed of glass and crystalline materials; Optical single crystals for optical switching elements, optical waveguides, optical fiber end faces, scintillators, etc .; solid laser single crystals; sapphire substrates for blue laser LEDs; semiconductor single crystals such as silicon carbide, gallium phosphide, gallium arsenide; for magnetic disks Glass substrates; magnetic heads; synthetic resins such as methacrylic resin and polycarbonate resin Etc., and the like.

  Hereinafter, the present invention will be described more specifically with reference to examples. The scope of the present invention is not limited to the contents of the examples.

[Example 1]
(Polymerization of thermoplastic polyurethane)
PTMG2000 containing polytetramethylene glycol (PTMG2000), 3-methyl-1,5-pentanediol (MPD), 1,4-butanediol (BD), and 4,4′-diphenylmethane diisocyanate (MDI) having a number average molecular weight of 2000 : MPD: BD: MDI The mass ratio was 32.0: 4.3: 13.2: 50.5. At this time, the molar ratio of BD and MPD is 80/20. The mixed liquid thus prepared was continuously supplied to a twin-screw extruder rotating coaxially with a metering pump, and continuous melt polymerization was performed to produce a thermoplastic polyurethane. The strand-shaped thermoplastic polyurethane continuously discharged from the twin-screw extruder was cooled in water and then pelletized with a pelletizer. The obtained pellets were dehumidified and dried at 70 ° C. for 20 hours to obtain a thermoplastic polyurethane having an intrinsic viscosity of 0.85 dl / g. Table 1 shows the storage elastic moduli of the obtained thermoplastic polyurethane at 80 ° C and 110 ° C.

  The storage elastic modulus of thermoplastic polyurethane at 80 ° C. and 110 ° C. was measured as follows. A thermoplastic polyurethane film having a length of 4 cm, a width of 0.5 cm, and a thickness of 400 μm ± 100 μm was prepared. Then, after measuring the thickness of the film with a micrometer, using a dynamic viscoelasticity measuring device (DVE Rheospectr, manufactured by Rheology Co., Ltd.) under the conditions of a frequency of 11 Hz and a heating rate of 3 ° C./min. The dynamic viscoelastic modulus at 80 ° C. and 110 ° C. was measured, and the storage elastic modulus was calculated.

(Production of thermoplastic polyurethane sheet by melt blown method)
Using the obtained thermoplastic polyurethane as a raw material, a thermoplastic polyurethane melted at a die temperature of 260 ° C. using a melt blow spinning device having slits for jetting heated air on both sides of a 0.3 mm diameter nozzle arranged in a row Was discharged at a rate of 0.5 g per minute per nozzle, and air heated to 270 ° C. was sprayed from the slit at 15 Nm ³ / min per 1 m width to make the thermoplastic polyurethane fine. By collecting the thinned thermoplastic polyurethane on a conveyor made of 50 mesh wire mesh 15 cm below the nozzle, thermoplastic polyurethane with an average fiber diameter of 16 μm, a porosity of 37% and a thickness of 2.5 mm Sheet A was obtained.

  Then, the surface of the thermoplastic polyurethane sheet A was ground to finish a circle having a thickness of 1.5 mm and a diameter of 38 mm. Then, a circular polishing pad having a diameter of 38 cm was prepared by forming grooves having a width of 1.0 mm and a depth of 0.8 mm concentrically at intervals of 6.5 mm on one surface of a sheet having a thickness of 1.5 mm.

(Evaluation of polishing performance)
The polishing rate and polishing nonuniformity of the obtained polishing pad were evaluated by the following methods. The obtained polishing pad was set in a CMP polishing apparatus (“MAT-BC15” manufactured by MTT Co., Ltd.). Then, using a diamond dresser (# 100 made by Allied Materials Co., Ltd.—80% coverage, diameter 19 cm, mass 1 kg), while flowing distilled water at a rate of 150 mL / min, the dresser rotational speed 140 rpm, the platen rotational speed The polishing pad was conditioned for 1 hour at 100 rpm.

  Next, a silicon wafer with a diameter of 4 inches having a PTEOS film with a film thickness of 1000 nm on the surface while supplying polishing slurry at a rate of 120 mL / min under the conditions of a platen rotation speed of 100 rpm, a head rotation speed of 99 rpm, and a polishing pressure of 27.6 kPa. Was polished for 60 seconds. And it conditioned for 30 seconds on the same conditioning conditions as mentioned above. The polishing slurry was prepared by mixing 100 parts by mass of water with 100 parts by mass of “SS-25” manufactured by Cabot Microelectronics. Thereafter, the silicon wafer was replaced, and polishing and conditioning were repeated in the same manner to polish a total of 10 wafers.

For the 10th polished silicon wafer, the film thickness of the PTEOS film before polishing and after polishing was measured for 49 points on the wafer surface, and the polishing rate was calculated. Further, an average value of 49 polishing rates was obtained. Furthermore, the nonuniformity of polishing was calculated by the following equation (1). A smaller non-uniformity value indicates that the PTEOS film is uniformly polished in the silicon wafer surface.
Nonuniformity (%) = (σ / R) × 100 (1)
(In formula (1), σ represents the standard deviation of the 49-point polishing rate, and R represents the average value of the 49-point polishing rate.)
Further, the 10th polished silicon wafer was observed using a color laser microscope “VK-X200” manufactured by Keyence Corporation at a magnification of 500 times to confirm the presence or absence of scratches. The results are shown in Table 1.

[Example 2]
Instead of the thermoplastic polyurethane sheet A obtained in Example 1, the thermoplastic polyurethane sheet A was heated and pressed under the conditions of a temperature of 235 ° C. and a pressure of 300 kN / cm ² , an average fiber diameter of 16 μm, and a porosity of 5 A polishing pad was obtained and evaluated in the same manner as in Example 1 except that 4% thermoplastic polyurethane sheet B was used. The results are shown in Table 1.

[Example 3]
In “Production of thermoplastic polyurethane sheet by melt blown method”, thermoplastic polyurethane melted at a die temperature of 245 ° C. is discharged at a rate of 0.5 g per minute per nozzle, and air heated to 255 ° C. is 10 Nm per 1 m width from the slit. ^A thermoplastic polyurethane sheet C having an average fiber diameter of 42 μm, a porosity of 44%, and a thickness of 1.9 mm was obtained in the same manner as in Example 1 except that the thermoplastic polyurethane was thinned by spraying at ³ / min. Then, a polishing pad was obtained and evaluated in the same manner as in Example 1 except that the thermoplastic polyurethane sheet C was used instead of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Example 4]
Instead of the thermoplastic polyurethane sheet C obtained in Example 3, the thermoplastic polyurethane sheet C was heated and pressed under the conditions of a temperature of 235 ° C. and a pressure of 300 kN / cm ² , an average fiber diameter of 42 μm, and a porosity of 3 A polishing pad was obtained and evaluated in the same manner as in Example 3 except that 6% thermoplastic polyurethane sheet D was used. The results are shown in Table 1.

[Example 5]
In “Production of thermoplastic polyurethane sheet by melt blown method”, thermoplastic polyurethane melted at a die temperature of 275 ° C. is discharged at a rate of 0.5 g per minute per nozzle, and air heated to 280 ° C. is 19 Nm per 1 m width from the slit. ^A thermoplastic polyurethane sheet E having an average fiber diameter of 10 μm, a porosity of 39%, and a thickness of 1.8 mm was obtained in the same manner as in Example 1 except that the thermoplastic polyurethane was thinned by spraying at ³ / min. Then, a polishing pad was obtained and evaluated in the same manner as in Example 1 except that the thermoplastic polyurethane sheet E was used instead of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Example 6]
Instead of the thermoplastic polyurethane sheet E obtained in Example 5, the thermoplastic polyurethane sheet E was heated and pressed under the conditions of a temperature of 235 ° C. and a pressure of 300 kN / cm ² , an average fiber diameter of 10 μm, and a porosity of 5 A polishing pad was obtained and evaluated in the same manner as in Example 5 except that 0.0% of the thermoplastic polyurethane sheet F was used. The results are shown in Table 1.

[Comparative Example 1]
The thermoplastic polyurethane pellets polymerized in Example 1 were charged into a single screw extruder having a cylinder diameter of 65 mm, extruded from a T-die at a cylinder temperature of 225 to 235 ° C. and a die temperature of 235 ° C., and cooled. A thermoplastic polyurethane sheet G having a thickness of 2 mm was molded. A circular polishing pad having a diameter of 38 cm was obtained and evaluated in the same manner as in Example 1 except that the thermoplastic polyurethane sheet G was used instead of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Comparative Example 2]
In “Production of thermoplastic polyurethane sheet by melt blown method”, thermoplastic polyurethane melted at a die temperature of 280 ° C. is discharged at a rate of 0.5 g per minute per nozzle, and air heated to 290 ° C. is 22 Nm per 1 m width from the slit. ^A thermoplastic polyurethane sheet H having an average fiber diameter of 4.9 μm, a porosity of 61%, and a thickness of 1.9 mm was obtained in the same manner as in Example 1 except that the thermoplastic polyurethane was thinned by jetting at ³ / min. . Then, a polishing pad was obtained and evaluated in the same manner as in Example 1 except that the thermoplastic polyurethane sheet H was used instead of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Comparative Example 3]
In “Production of thermoplastic polyurethane sheet by melt blown method”, thermoplastic polyurethane melted at a die temperature of 230 ° C. is discharged at a rate of 0.5 g / min. Per nozzle, and air heated to 235 ° C. is 8 A thermoplastic polyurethane sheet I having an average fiber diameter of 66 μm, a porosity of 55%, and a thickness of 1.9 mm was obtained in the same manner as in Example 1 except that the thermoplastic polyurethane was thinned by jetting 0.0 Nm ³ / min. . Then, a polishing pad was obtained and evaluated in the same manner as in Example 1 except that the thermoplastic polyurethane sheet I was used instead of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Comparative Example 4]
The pellets of the thermoplastic polyurethane polymerized in Example 1 were charged into a single screw extruder having a cylinder diameter of 65 mm, extruded from a T-die under conditions of a cylinder temperature of 225 to 235 ° C. and a die temperature of 235 ° C., and the temperature was adjusted to 60 ° C. The sheet having a thickness of 2.0 mm was formed by passing through a roll having a gap interval of 1.8 mm. Next, the obtained sheet is put into a pressure vessel, and carbon dioxide is dissolved for 5 hours under conditions of a temperature of 130 ° C. and a pressure of 8.0 MPa to obtain a gas dissolving sheet containing 2% by weight (saturated amount) of carbon dioxide. It was. After cooling to room temperature, the pressure was set to normal pressure, and the gas-dissolving sheet was taken out from the pressure vessel. Next, the obtained gas-dissolved sheet was immersed in 160 ° C. silicone oil for 3 minutes and then taken out and cooled to room temperature to obtain a polyurethane foam sheet J. The density of the polyurethane foam sheet J was 0.80 g / cm ³ , the cell size was 40 to 80 μm, and the porosity was 28%. Then, a circular polishing pad having a diameter of 38 cm was obtained and evaluated in the same manner as in Example 1 except that the polyurethane foam sheet J was used instead of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Comparative Example 5]
A polyether urethane polymer, 4,4′-methylene-bis-2-chloroaniline, and hollow polymer microspheres (Expercel 551DE) were mixed at a mass ratio of 78: 20: 2.0, and the mixture was mixed with a RIM molding machine. A polyurethane foam sheet K having a thickness of 2 mm made of thermosetting polyurethane was obtained by discharging into a mold and performing pressure molding. The polyurethane foam sheet K had a density of 0.71 g / cm ³ , the average diameter of closed cells was 30 μm, and the porosity was 30%. A circular polishing pad having a diameter of 38 cm was obtained and evaluated in the same manner as in Example 1 except that the polyurethane foam sheet K was used in place of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Comparative Example 6]
(Polymerization of thermoplastic polyurethane)
Number average molecular weight 1000 polytetramethylene glycol [abbreviation: PTMG1000], 3-methyl-1,5-pentanediol [abbreviation: MPD], 1,4-butanediol [abbreviation: BD], and 4,4′-diphenylmethane Diisocyanate [abbreviation: MDI] was mixed so that the mass ratio of PTMG1000: MPD: BD: MDI was 19.2: 4.5: 9.3: 67.0. At this time, the molar ratio of BD and MPD is 80/20. And the mixed liquid adjusted in this way was continuously supplied with the metering pump to the twin-screw extruder which rotates coaxially, the continuous melt polymerization was performed, and the thermoplastic polyurethane was manufactured. The resulting thermoplastic polyurethane melt was continuously extruded into water in a strand form, then chopped into pellets with a pelletizer, and the resulting pellets were dehumidified and dried at 70 ° C. for 20 hours to obtain an intrinsic viscosity of 0. A 0.71 dl / g thermoplastic polyurethane was obtained. The storage elastic modulus at 80 ° C. and 110 ° C. is shown in Table 1.

(Production of thermoplastic polyurethane sheet by melt blown method)
A thermoplastic polyurethane sheet was prepared under the same conditions as in Example 1 except that the thermoplastic polyurethane was used, and a thermoplastic polyurethane sheet L having an average fiber diameter of 48 μm, a porosity of 35%, and a thickness of 2.0 mm was obtained. . A circular polishing pad having a diameter of 38 cm was obtained and evaluated in the same manner as in Example 1 except that the thermoplastic polyurethane sheet L was used instead of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

[Comparative Example 7]
(Polymerization of thermoplastic polyurethane)
Number average molecular weight 2000 polytetramethylene glycol [abbreviation: PTMG2000], 3-methyl-1,5-pentanediol [abbreviation: MPD], 1,4-butanediol [abbreviation: BD], and 4,4′-diphenylmethane Diisocyanate [abbreviation: MDI] was mixed so that the mass ratio of PTMG2000: MPD: BD: MDI was 42.0: 7.2: 19.5: 31.3. At this time, the molar ratio of BD and MPD is 80/20. And the mixed liquid adjusted in this way was continuously supplied with the metering pump to the twin-screw extruder which rotates coaxially, the continuous melt polymerization was performed, and the thermoplastic polyurethane was manufactured. The resulting thermoplastic polyurethane melt was continuously extruded into water in a strand form, then chopped into pellets with a pelletizer, and the resulting pellets were dehumidified and dried at 70 ° C. for 20 hours to obtain an intrinsic viscosity of 0. A 94 dl / g thermoplastic polyurethane was obtained. The storage elastic modulus at 80 ° C. and 110 ° C. is shown in Table 1.

(Production of thermoplastic polyurethane sheet by melt blown method)
A thermoplastic polyurethane sheet was prepared under the same conditions as in Example 1 except that the thermoplastic polyurethane was used, and a thermoplastic polyurethane sheet M having an average fiber diameter of 3.5 μm, a porosity of 43%, and a thickness of 2.0 mm was obtained. Obtained. A circular polishing pad having a diameter of 38 cm was obtained and evaluated in the same manner as in Example 1 except that the thermoplastic polyurethane sheet M was used in place of the thermoplastic polyurethane sheet A. The results are shown in Table 1.

  From the results of Table 1, no scratch was observed in any of the polishing pads of Examples 1 to 6 according to the present invention. Also, the polishing rate could be increased and the non-uniformity was low. In addition, from comparisons between Example 1 and Example 2, Example 3 and Example 4, Example 5 and Example 6, the polishing rate and non-uniformity are easily adjusted by controlling the porosity. You can see that you can. On the other hand, in the case of Comparative Example 1 using a polyurethane sheet having no voids formed by a T-die using the same thermoplastic polyurethane as in Example 1, since the rigidity is high, the polishing rate is high, but the scratch is Many occurred. Moreover, in the case of the comparative example 2 whose average fiber diameter of a nonwoven fabric is too small, since the rigidity became low, the polishing rate fell. Furthermore, in the case of Comparative Example 3 in which the average fiber diameter of the nonwoven fabric was too large, the rigidity was too high, the followability was lowered, and the non-uniformity was increased. Further, a polishing pad obtained by using the polyurethane foam sheet of Comparative Example 4 formed by infiltrating a gas into a polyurethane sheet having no voids formed by a T-die using the same thermoplastic polyurethane as in Example 1. In some cases, even if voids were formed using the same thermoplastic polyurethane as in Example 1, non-uniformity was increased due to low followability, and scratches were generated because there were no or few communication holes. Further, the polishing pad of Comparative Example 5 using a polyurethane foam sheet made of thermosetting polyurethane also had scratches because it had no or few communication holes. In addition, the polishing pad of Comparative Example 6 using a nonwoven fabric formed from a thermoplastic polyurethane having a high storage elastic modulus at 80 ° C. was too rigid and generated many scratches. Moreover, the polishing pad of Comparative Example 7 using a nonwoven fabric formed from a thermoplastic polyurethane having a low storage elastic modulus at 80 ° C. had a low polishing rate and a very high nonuniformity because the rigidity was too low.

  It can be preferably used for polishing in manufacturing processes of various semiconductor devices, MEMS (Micro Electro Mechanical Systems) and the like.

DESCRIPTION OF SYMBOLS 10 Polishing pad 11 Rotating surface plate 12 Slurry supply nozzle 13 Carrier 14 Pad conditioner 15 Base material 16 Polishing slurry 20 CMP apparatus

Claims (7)

80 storage modulus at ℃ is characterized (excluding those containing the impregnated elastic polymer) or Ranaru that thermoplastic average diameter 10~50μm fiber nonwoven fabric made of polyurethane is 150~900MPa Polishing pad.   The polishing pad according to claim 1, wherein the porosity is 1 to 50%.   The polishing pad according to claim 1 or 2, wherein the thermoplastic polyurethane has a storage elastic modulus at 110 ° C of 40 MPa or less.   The polishing pad according to any one of claims 1 to 3, wherein the thermoplastic polyurethane is obtained by melt polymerization of a polymer diol, an organic diisocyanate, and a chain extender.   The polishing pad according to claim 4, wherein the polymer diol contains 30 to 100% by mass of polytetramethylene glycol.   The polishing pad according to claim 5, wherein the polytetramethylene glycol has a number average molecular weight of 1200 to 4000. A chemical mechanical polishing method for a substrate, comprising:
The substrate and the substrate in a state in which the surface of the polishing pad and the surface of the substrate are pressed against each other while dripping polishing slurry onto the surface of the polishing pad or substrate according to any one of claims 1 to 6. A chemical mechanical polishing method comprising polishing a surface of the substrate by moving a polishing pad relatively.

Images