JP2005251851A - Polishing pad and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad that can accurately and uniformly polish the surface of an object to be polished, such as semiconductor wafer etc., with a strong polishing force, and can suppress the occurrence of scratches, and to provide a method of polishing semiconductor wafer which uses the pad. <P>SOLUTION: In the polishing pad used for chemical mechanical polishing performed for polishing semiconductor wafers, fine particles of an organic resin, such as the fluorine-based resin, polyolefin-based resin, are scattered in a matrix resin in the polishing region of the fine foam of a polyurethane resin. In addition, the SP value of the fine particles of the organic resin is smaller than that of the matrix resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing pad used for planarizing unevenness of a semiconductor wafer surface by chemical mechanical polishing (CMP), and more specifically, local polishing by coarse abrasive particles or generation of scratches due to excessive contact of abrasive particles. The present invention relates to a polishing pad that can be prevented and a method for polishing a semiconductor wafer using the polishing pad.

  Conventionally, semiconductor wafers are mirror-polished by so-called chemical mechanical polishing (CMP) or planarization of interlayer insulating films and conductive films in the finishing process and multi-layer wiring processes in devices. Recently, a CMP method that applies mirror processing of a silicon wafer has been adopted as a planarization method. This apparatus includes a polishing plate supported by a rotating polishing plate rotating shaft and having a polishing pad bonded to the surface, a dresser for electrodepositing diamond powder and the like on a metal plate, and a dresser for sharpening the surface of the polishing pad. A polishing slurry supply apparatus having a carrier for holding a polished body (hereinafter referred to as a wafer) on which a polishing layer such as an insulating film is formed by a wafer backing film, and a polishing slurry supply nozzle for supplying polishing slurry onto the polishing pad It is generally composed of

  As one method, after dressing (grinding) the polishing pad with a dresser, the polishing pressure is adjusted while rotating the polishing plate rotation shaft and the carrier rotation shaft and supplying the polishing slurry from the polishing slurry supply nozzle to the center of the polishing pad. There is a method of polishing a wafer by pressing the wafer onto a polishing pad by a mechanism.

  In such a CMP method, there is a problem that (micro) scratches are generated in a layer to be polished such as an insulating film of a wafer, a polishing rate varies, and a polishing amount has a large variation in a wafer surface.

  In order to suppress the generation of micro scratches, polishing pad shavings and dresser diamond powder generated during dressing of the polishing pad, interlayer film, wafer debris, agglomerates of abrasive particles, polished polishing slurry, etc. ( Hereinafter, it is necessary to discharge these to the outside of the polishing pad.

  In such a conventional CMP apparatus, a measure is taken such that the polishing slurry is sufficiently flowed to the center of the polishing pad without interruption during the polishing operation, and impurities are removed or pushed out of the polishing pad by this polishing slurry.

  In this way, when a dressing layer is formed on the pad surface by dressing and the polishing slurry is supplied to polish the wafer, the polishing slurry is pushed out by the centrifugal force due to the rotation of the polishing pad and pressing the wafer against the polishing pad. Is discharged outside the polishing pad without directly contributing to polishing, and therefore, an expensive polishing slurry is consumed excessively. In addition, generation of scratches due to local polishing due to impurities becomes a problem.

  In CMP polishing, characteristics such as uniformity of the polishing amount over the entire surface of the wafer, selective polishing of convex portions of uneven steps, flatness after polishing of uneven portions, etc. are required, and further generation of scratches must be suppressed. is there. In response to these requirements, a number of polishing pads have been conventionally developed and studied (Patent Documents 1 to 10, etc.).

  Patent Document 1 discloses a polishing pad in which a synthetic leather layer as a polishing layer is laminated on an elastic polyurethane layer. However, in this polishing pad, regarding the uniformity of the entire surface, the elastic polyurethane layer serves to make the load applied to the wafer uniform, but because the outermost polishing layer uses soft synthetic leather, There is no problem such as scratches, but there is a problem that the flattening characteristics in a minute region are not good.

  In Patent Document 2, a polishing surface is provided, a rigid element having a selected thickness and rigidity is provided adjacent to the polishing surface, and a substantially uniform force is applied to the rigid element. In order to achieve this, an elastic element is provided adjacent to the rigid element, and the rigid element and the elastic element impart an elastic bending force to the polishing surface to induce a controlled bending on the polishing surface, A polishing pad is disclosed that is adapted to the overall shape of the workpiece surface and maintains controlled stiffness with respect to the local shape of the workpiece surface. However, in the polishing pad having the structure of the polishing layer, the rigid layer, and the elastic layer, the hardness is set so that no scratch is generated in the surface polishing layer. The characteristics are covered by the second rigid layer. Therefore, the thickness of the polishing layer is defined to be as small as 0.003 inches or less, and when this thickness is actually used, the polishing layer is also scraped, and there is a problem that the product life is shortened.

  Patent Document 3 discloses a polishing pad for bonding a hard resin powder such as polyurethane resin or ultra high molecular weight polyethylene in a soft resin such as polyurethane resin. However, this polishing pad is characterized in that fine particles that do not desorb are added and the polishing rate is increased by the fine particles, but there is no effect of reducing scratches.

  Patent Document 4 discloses a polishing pad in which foamed urethane resin is mixed with cerium oxide particles. However, in this polishing pad, the abrasive grains are contained in the pad, but the concentration of the abrasive grains is insufficient, and it is necessary to use them together with the polishing slurry. Further, since the resin and the abrasive grains are simply mixed in the solvent, there is a problem that the particles are aggregated to cause scratches.

  In Patent Documents 5 and 6, abrasive particles are dispersed in a binder solution dissolved in a solvent, a polishing pad coated on a film, or abrasive particles are dispersed in a binder resin, and coated on a resin substrate. A polishing pad laminated with a softer member is disclosed. In these polishing pads, the uniformity is improved by laminating, but since the thickness of the coated fixed abrasive layer cannot be increased, the fine irregularities created on the surface are in use. There is a problem that the product life is shortened.

  Patent Document 7 discloses a polishing pad containing inorganic particles and polymer fine particles having a diameter of 0.01 to 300 μm in an epoxy resin. However, these particles are for further improving the acid resistance and alkali resistance of the polishing pad.

  Patent Document 8 discloses a polishing pad made of a material containing fine polymer particles having an official moisture content of 5% or more. However, this polishing pad is intended to prevent the adsorption of the abrasive and the dust adsorption to the wafer.

  Patent Document 9 discloses a polishing pad comprising composite particles in which abrasive particles for polishing are attached to the surface of elastic particles. However, this polishing pad is intended to uniformly press the abrasive particles for polishing against the wafer with elastic particles.

Further, although not an improvement of the polishing pad itself, Patent Document 10 discloses a method of polishing by mixing particles for preventing scratches such as polyurethane particles in a slurry containing abrasive particles for polishing. However, although this polishing method can be expected to be effective in preventing scratches, there is a problem that the anti-scratch particles settle in the slurry and there is a problem in floating stability, and the uniformity during polishing is lowered.
US Pat. No. 3,504,457 Japanese Patent Application Laid-Open No. 06-077185 JP 2000-354950 A JP 2001-009697 A Special Table 2001-505589 Special table 2001-512375 gazette Japanese Patent Laid-Open No. 11-138420 JP 2002-009024 A JP 2003-266320 A JP 09-285957 A

  The present invention is not able to solve the conventional polishing pad and the polishing method using the same as described above. Impurities in a polishing pad used in a polishing process for flattening fine irregularities of a fine pattern on a semiconductor wafer ( Solves problems such as generation of scratches due to foreign matter) and agglomeration of abrasive grains, and lack of polishing uniformity, and the surface of an object to be polished such as a semiconductor wafer can be polished uniformly with high polishing power. It is an object of the present invention to provide a polishing pad capable of suppressing the occurrence of the above and a method for polishing a semiconductor wafer using the polishing pad.

  As a result of intensive studies to solve the above object, the present inventors dispersed organic resin fine particles in a matrix resin in a polishing region of a polishing pad used for chemical mechanical polishing for polishing a semiconductor wafer, and the matrix resin By making the SP value of the organic resin fine particles smaller than the SP value, a polishing pad that can accurately and uniformly polish the surface of an object to be polished, such as a semiconductor wafer, with high polishing force, and its polishing pad can be suppressed. The present inventors have found that a method for polishing a semiconductor wafer can be provided, and the present invention has been completed.

  That is, the present invention is a polishing pad used for chemical mechanical polishing for polishing a semiconductor wafer, in which organic resin fine particles are dispersed in a matrix resin in a polishing region of the polishing pad, and the organic resin is determined from the SP value of the matrix resin. The present invention relates to a polishing pad having a small SP value of fine particles.

  When the polishing pad of the present invention is used for polishing a semiconductor wafer or the like, as the polishing progresses, organic resin fine particles are gradually detached from the polishing region due to wear of the polishing region of the polishing pad and mixed into the polishing slurry, thereby acting as a cushion. However, it is considered that it is possible to provide polishing with excellent uniformity without scratches as a result.

Furthermore, in order to implement this invention suitably,
The organic resin fine particles are insoluble in the aqueous slurry,
The organic resin fine particles have a particle size of 0.1 μm to 100 μm,
The surface of the organic resin fine particles is formed from a negatively charged resin,
At least the surface layer of the organic resin fine particles is made of at least one resin selected from the group consisting of a fluorine resin, a silicone resin, a polyolefin resin, and a polystyrene resin,
The matrix resin is a polyurethane resin,
The polyurethane resin is a fine foam,
The fine foam has a specific gravity of 0.5 to 1.0 g / cm ³ ;
The fine foam has a hardness of 45 to 65 degrees;
The fine foam preferably has a compression ratio of 0.5 to 5.0%.

  As another aspect of the present invention, there is a method for polishing a semiconductor wafer using the polishing pad of the present invention.

  A polishing pad used for chemical mechanical polishing for polishing a semiconductor wafer of the present invention is obtained by dispersing organic resin fine particles in a matrix resin in a polishing region and making the SP value of the organic resin fine particles smaller than the SP value of the matrix resin. A polishing pad capable of accurately and uniformly polishing the surface of an object to be polished, such as a semiconductor wafer, with high polishing force and suppressing the generation of scratches, and a method for polishing a semiconductor wafer using the polishing pad have been provided. .

  Hereinafter, the polishing pad of the present invention will be described in more detail. The polishing pad according to the present invention is preferably used as a polishing pad used when performing planarization treatment of an object to be polished by CMP, and suppresses variation in polishing rate, and on each surface of the entire surface of the object to be polished. A polishing pad that suppresses the occurrence of scratches due to the removal of organic resin fine particles from the appropriate polishing surface between the object to be polished and the polishing pad, and provides a uniform surface over the entire surface of the object to be polished. is there.

  The polishing pad in the present invention is a single-layer pad having only a polishing region, which is a hard surface layer generally used in the past, or a polishing region and a polishing region that are a hard surface layer that comes into contact with an object to be polished such as a wafer, and a platen. It may be a laminated pad having at least two elastic support layers positioned therebetween, or may be a laminated polishing pad such as a multilayer polishing pad in which other layers are stacked. From the viewpoint of productivity and performance, those having at least two elastic support layers located between the polishing region and the platen are preferable.

  The above-mentioned laminated polishing pad is roughly formed by a polishing region and an elastic support layer, and the polishing region was performed in accordance with hardness (JIS K6253-1997. 2 cm × 2 cm (thickness: arbitrary) The polished area cut out to a size of 5 mm was used as a sample for hardness measurement, and was allowed to stand for 16 hours in an environment of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%. The hardness was measured using a hardness meter (Asker D type hardness meter manufactured by Kobunshi Keiki Co., Ltd.). When the hardness is less than 45, the planarity (flatness) of the object to be polished is lowered, and when it exceeds 65, the planarity is good, but the uniformity (uniformity) of the object to be polished tends to decrease. The elastic support layer has a hardness (according to JIS K6253-1997, Asker A hardness meter manufactured by Kobunshi Keiki Co., Ltd.) of 25 to 100, preferably 30 to 85. The polishing region has a thickness of 0.5 to 3.0 mm, preferably 0.8 to 2.0 mm, and the elastic support layer has a thickness of 0.5 to 3.0 mm, preferably 1.0 to 2.0 mm. It is desirable to have 2.0 mm.

  The material for the elastic support layer is preferably polyethylene foam, polyurethane foam, polyester nonwoven fabric, or the like, but is not limited thereto. When the hard surface layer and the elastic support layer are formed of a nonwoven fabric, the nonwoven fabric may be impregnated with an impregnating agent such as polyurethane resin. However, the polishing pad may be made of a material other than the above as long as the above hardness range is satisfied.

  In the case of a single-layer polishing pad, it is desirable that the thickness (pad thickness) is 0.5 to 5.0 mm, preferably 0.8 to 3.0 mm.

  In the polishing pad of the present invention, as described above, the organic resin fine particles are dispersed in the matrix resin in the polishing region, and the SP value of the organic resin fine particles is smaller than the SP value of the matrix resin. The matrix resin desirably has an SP value of 9 or more, preferably 9.5 or more, and more preferably 9.6 to 14. If the SP value of the matrix resin is less than 9, it is generally a material having a very high water repellency, and the slurry on the surface of the polishing pad is repelled, so that a sufficient polishing rate cannot be obtained. The SP value (Solubility Parameter) is an index indicating the degree of hydrophilicity or hydrophobicity of resins, and is an important index for designing the compatibility and dispersibility between resins. The SP value is P.I. A. J. et al. It can be calculated by the method proposed by Small. [J. Appl. Chem. , 3, 71 (1953)]

  Examples of the matrix resin in the polishing region are not particularly limited as long as it has a larger SP value than the organic resin fine particles dispersed therein, but polyethylene terephthalate (SP value = 10.7), polybutylene terephthalate (SP value). = 10.8), polyester resins such as polytrimethylene terephthalate (SP value = 12.1), polyhexamethylene terephthalate (SP value = 10.0), polylactic acid (SP value = 9.5), nylon 6 (SP value = 12.7), polyamide resin such as nylon 66 (SP value = 13.6), vinyl acetate resin (SP value = 9.4 to 12.6), polyurethane resin (SP value = 10.1). 0), polycarbonate resin (SP value = 9.8-10.0), polyphenylene sulfide (SP value = 12.5), polyether ester keto (SP value = 10.4 to 11.3), and the like. Among these, a polyurethane resin is preferable, and a polyurethane resin fine foam is more preferable.

The fine foam preferably has a specific gravity of 0.5 to 1.0 g / cm ³ , preferably 0.7 to 0.9 g / cm ³ . When the specific gravity is less than 0.5 g / cm ^3, the strength of the surface of the polishing region decreases, the planarity of the object to be polished decreases, and when it exceeds 1.0 g / cm ³ , the surface of the polishing region becomes fine. Although the number of bubbles is reduced and planarity is good, the polishing rate tends to be low.

  The fine foam has a hardness of 45 to 65 degrees, preferably 45 to 60 degrees. When the hardness is less than 45 degrees, the planarity of the object to be polished decreases. When the hardness is greater than 65 degrees, the planarity is good, but the uniformity of the object to be polished tends to decrease. is there.

  The fine foam preferably has a compression ratio of 0.5 to 5.0%, preferably 0.5 to 3.0%. If the compression ratio is within the above range, it is possible to sufficiently achieve both planarity and uniformity.

  The fine foam desirably has a compression recovery rate of 50 to 100%. When the compression recovery rate deviates from this range, it is not preferable because a large change appears in the polishing layer thickness and the stability of the polishing characteristics deteriorates as the repeated load applied to the object is applied to the polishing region during polishing. .

  The fine foam desirably has a storage elastic modulus of 200 MPa or more at a measurement temperature of 40 ° C. and a measurement frequency of 1 Hz. The storage elastic modulus means an elastic modulus measured by applying a sinusoidal vibration to a fine foam using a tensile test jig with a dynamic viscoelasticity measuring apparatus. When the storage elastic modulus is less than 200 MPa, the strength of the surface of the polishing region is lowered, and the planarity (flatness) of the object to be polished is deteriorated.

  When a polyurethane resin is foamed, the foaming method can be shared by foaming with a chemical foaming agent, foaming that mixes mechanical foam, and mixing of a hollow body or a precursor that becomes a microhollow body by heat. It may be.

  The polyurethane resin used in the polishing region of the present invention comprises an isocyanate-terminated urethane prepolymer and an organic diamine compound, and the isocyanate-terminated urethane prepolymer comprises a polyisocyanate, a high molecular polyol and a low molecular polyol. Examples of the above polyisocyanates include 2,4- and / or 2,6-diisocyanatotoluene, 2,2′-, 2,4′- and / or 4,4′-diisocyanatodiphenylmethane, 1,5 -Naphthalene diisocyanate, p- and m-phenylene diisocyanate, dimeryl diisocyanate, xylylene diisocyanate, diphenyl-4,4'-diisocyanate, 1,3- and 1,4-tetramethylxylidene diisocyanate, tetramethylene diisocyanate, 1, 6-hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (= isophorone diisocyanate), bis- ( 4 Isocyanatocyclohexyl) methane (= hydrogenated MDI), 2- and 4-isocyanatocyclohexyl-2'-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanatomethyl) -cyclohexane, bis- (4-isocyanato-3-methylcyclohexyl) methane, and the like.

  Examples of the polymer polyol include hydroxy-terminated polyesters, polycarbonates, polyester carbonates, polyethers, polyether carbonates, polyester amides, etc. Of these, polyethers and polycarbonates having good hydrolysis resistance are preferable, Polyether is particularly preferable from the viewpoint of price and melt viscosity. Polyether polyols include reaction products of starting compounds having reactive hydrogen atoms with alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin or mixtures of these alkylene oxides. It is done. Starting compounds having reactive hydrogen atoms include water, bisphenol A, and dihydric alcohols described above to produce polyester polyols.

  Further, examples of the polycarbonate having a hydroxy group include diols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol and / or polytetramethylene glycol. And the reaction product of phosgene, diallyl carbonate (eg diphenyl carbonate) or cyclic carbonate (eg propylene carbonate). Examples of the polyester polyol include a reaction product of a dihydric alcohol and a dibasic carboxylic acid, but in order to improve hydrolysis resistance, a longer distance between ester bonds is preferable. A combination is desirable. The dihydric alcohol is not particularly limited, but for example, ethylene glycol, 1,3- and 1,2-propylene glycol, 1,4- and 1,3- and 2,3-butylene glycol, 1,6-hexane. Glycol, 1,8-octanediol, neopentyl glycol, cyclohexanedimethanol, 1,4-bis- (hydroxymethyl) -cyclohexane, 2-methyl-1,3-propanediol, 3-methyl-1,5 -Pentanediol, 2,2,4-trimethyl-1,3-pentanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, dibutylene glycol and the like.

  The dibasic carboxylic acid includes aliphatic, alicyclic, aromatic and / or heterocyclic ones. From the necessity of making the terminal NCO prepolymer to be liquid or low melt viscosity, An alicyclic group is preferred, and in the case of applying an aromatic system, combined use with an aliphatic or alicyclic group is preferred. Examples of these carboxylic acids include, but are not limited to, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid (o-, m-, p-), dimer-fatty acids such as oleic acid and the like. These polyester polyols may have a part of carboxyl end groups. For example, a lactone such as ε-caprolactone or a polyester of a hydroxycarboxylic acid such as ε-hydroxycaproic acid can be used.

  Examples of the low molecular polyol include dihydric alcohols used to produce the above-described polyester polyol. Examples of the low molecular polyol of the present invention include diethylene glycol, 1,3-butylene glycol, and 3-methyl-1,5. It is preferable to use any one of -pentanediol and 1,6-hexamethylene glycol or a mixture thereof. When ethylene glycol or 1,4-butylene glycol, which is a low molecular weight polyol other than the present invention, is used, the reactivity at the time of cast molding becomes too fast, and the hardness of the finally obtained polyurethane abrasive molding becomes high. Therefore, the abrasive becomes brittle and the surface of the object to be polished is easily damaged. On the other hand, if a long-chain dihydric alcohol is used rather than 1,6-hexamethylene glycol, the reactivity at the time of cast molding and the hardness of the final polyurethane abrasive molding can be obtained. Although it is too expensive, it is not practical.

  The isocyanate component is appropriately selected according to the pot life required at the time of casting, and the terminal NCO prepolymer to be produced needs to have a low melt viscosity. Applied at. Specific examples thereof include, but are not limited to, 2,4- and / or 2,6-diisocyanatotoluene, 2,2′-, 2,4′- and / or 4,4′-diisocyanate. Natodiphenylmethane, 1,5-naphthalene diisocyanate, p- and m-phenylene diisocyanate, dimeryl diisocyanate, xylylene diisocyanate, diphenyl-4,4′-diisocyanate, 1,3- and 1,4-tetramethylxylidene diisocyanate, Tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (= isophorone) Diisocyanate), Su- (4-isocyanatocyclohexyl) methane (= hydrogenated MDI), 2- and 4-isocyanatocyclohexyl-2'-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanatomethyl) -Cyclohexane, bis- (4-isocyanato-3-methylcyclohexyl) methane, and the like. The organic diamine compound used in the present invention is not particularly limited. For example, 3,3′-dichloro-4,4′-diaminodiphenylmethane, chloroaniline-modified dichlorodiaminodiphenylmethane, 1,2-bis (2- Aminophenylthio) ethane, trimethylene glycol-di-p-aminobenzoate, 3,5-bis (methylthio) -2,6-toluenediamine and the like.

  In addition, a silicone surfactant may be added to the polyurethane resin layer used in the present invention for the purpose of controlling the foamed state. The amount of the surfactant to be added is preferably the minimum amount capable of appropriately controlling the foaming state, but is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less and 0.5% or more based on the total amount of the urethane polymer. Is good. When the amount of the surfactant is larger than this, the urethane resin becomes soft and the planarization characteristics deteriorate. Moreover, when the amount of the surfactant is less than this range, a good foamed state cannot be obtained. Any silicone surfactant may be used in the present invention, but a dimethylpolysiloxane-polyoxyalkyl copolymer is preferred.

  The matrix resin in the polishing region of the polishing pad of the present invention is any of these polyurethane resins and has an SP value of 9.0 or more, preferably 9.5 or more, more preferably 9.6 to 14 as described above. Those having are preferably selected and used.

  In the polishing pad of the present invention, as described above, the organic resin fine particles are dispersed in the matrix resin in the polishing region, and the SP value of the organic resin fine particles is required to be smaller than the SP value of the matrix resin. Is. When the difference in SP value between the matrix resin and the organic resin fine particles is 1.0 or more, particularly 1.5 or more, that is, when the organic resin fine particles are uniformly dispersed in the matrix resin, Its characteristics can be demonstrated. The feature is that the organic resin fine particles are gradually detached from the polishing area due to wear of the polishing area during polishing and mixed with the slurry to provide a cushioning action, which shows the effect of preventing local polishing by foreign matter and aggregates. Is. When the SP value of the organic resin fine particles is equal to or higher than the SP value of the matrix resin, the fine particles are difficult to be detached from the polishing pad.

  The organic resin fine particles used for the polishing pad of the present invention desirably have an SP value (Solubility Parameter) of 8.5 or less, preferably 8.0 or less, more preferably 6.0 to 8.0. If the SP value of the organic resin fine particles is greater than 8.5, the difference from the matrix resin is reduced, the adhesion between the matrix resin and the fine particles is increased, and the fine particles are less likely to fall off the polishing pad.

  The organic resin fine particles used in the polishing pad of the present invention are desirably insoluble in the aqueous slurry. This is because if particles that dissolve in the slurry are used, the particles dissolve in the slurry during polishing, and the cushioning effect by the particles cannot be obtained. In this specification, “the organic resin fine particles are insoluble in the aqueous slurry” means that when the organic resin fine particles are added to the aqueous slurry and left at room temperature for 10 minutes or more, the diameter of the organic resin fine particles is Say that does not get smaller.

  The organic resin fine particles used in the polishing pad of the present invention desirably have a particle diameter of 0.1 μm to 100 μm. When the particle diameter of the organic resin fine particles is smaller than 0.1 μm, the size becomes the same as the surface fluff of the polishing pad by dressing, and the fine particles are buried in the surface of the polishing pad, and the cushion effect by the fine particles cannot be obtained. When the particle diameter of the organic resin fine particles is larger than 100 μm, the surface of the polishing pad and the wafer surface are too far apart, and a sufficient polishing rate cannot be obtained. In the present specification, the “particle diameter of the organic resin fine particles” refers to the particle diameter of the organic resin fine particles measured using a centrifugal sedimentation method, a dynamic light scattering method, or the like.

  The organic resin fine particles used in the polishing pad of the present invention are preferably solid. When hollow fine particles are used, there is a possibility that the fine particles are detached from the pad and are crushed by the polishing load during polishing as will be described later.

  Examples of the resin used for the organic resin fine particles of the present invention are not particularly limited as long as the resin has an SP value smaller than that of the matrix resin as described above. For example, polyethylene (SP value = 7.9), polypropylene (SP value) = 8.1), polyolefin resins such as polymethylpentene (SP value = 8.0), fluorine resins (SP value = 6.2 to 6.5), silicone resins (SP value = 6.0) 7.0) and mixtures thereof.

  In the present invention, the surface of the organic resin fine particles is desirably formed from a resin that is negatively charged. However, in the present specification, the term “negatively charged resin” refers to an organic resin having a surface formed of such a resin. A resin that collects the above-mentioned fine particles on the positive electrode side when an electrode is inserted into a solution in which the fine particles are dispersed and energized. Examples of negatively charged resins used in the organic resin fine particles of the present invention include polyolefin resins such as polyethylene resins and polystyrene resins, fluorine resins, and the like. In the present invention, as described above, the added organic resin fine particles are detached from the pad during polishing and mixed into the slurry. However, when the surface of the organic resin fine particles is negatively charged, the alkaline is widely used as a slurry. The surface potential of the silica abrasive is opposite to the surface potential of the silica particles, the silica particles are adsorbed on the surface of the organic resin fine particles, and the silica particles and the organic resin fine particles are combined. This significantly improves the polishing characteristics.

  The organic resin fine particles of the present invention or the resin used for the organic resin fine particles has a hardness (Asker D type hardness meter) of 10 to 70, preferably 20 to 60. If the hardness of the organic resin fine particles is higher than 70, the fine particles themselves are too hard to obtain a sufficient polishing rate. If the hardness is lower than 10, the fine particles cannot withstand the polishing load, and the cushion effect by the fine particles is obtained. Disappear.

  In the polishing pad of the present invention, the amount of the organic resin fine particles in the polishing region from the matrix resin and the organic resin fine particles dispersed therein is not particularly limited, but is preferably 2 to 30% by weight and less than 2% by weight. If not, the effect of dispersing the organic resin fine particles is small, and if it exceeds 30% by weight, the polishing characteristics and mechanical resistance of the polishing region are unsatisfactory.

  Concentric grooves or the like may be formed on the surface of the polishing region of the polishing pad in the present invention. The forming method is not particularly limited, and examples thereof include a cutting method, an embossing roll method, a mold forming method, a transfer method, and an exposure curing method.

  When the embossing roll method is used, the embossing roll method is used. Using a processing roll in which micro-dents having the same shape are arranged on one roll of the embossing device, the softened resin is extruded and processed into a sheet shape by an embossing device, and cooled by a cooling roll to obtain a target polishing pad. At this time, it is desirable to use a metal match method in which both rolls are made of metal for the roll combination of the embossing device. By using a metal roll, the roll temperature can be finely adjusted, and a crystalline thermoplastic resin having a narrow temperature control range during embossing can also be used. After embossing is difficult to heat and soften the original fabric uniformly in the sheet reheating process, and is not suitable for fine processing requiring dimensional accuracy. The embossing roll method is characterized by the fact that most thermoplastic resins can be used and can be mass-produced at low cost.

  The abrasive slurry (abrasive) that can be used when using the polishing pad of the present invention is a silica abrasive, a ceria abrasive, a zirconia abrasive, and the like, but is not limited thereto. Moreover, you may use the abrasive | polishing agent which does not contain an abrasive grain. As an abrasive | polishing agent which does not contain an abrasive grain, what is disclosed by Unexamined-Japanese-Patent No. 11-135466 is mentioned, for example.

  There is no restriction | limiting in the apparatus used for grinding | polishing, It can use with a disk type polishing apparatus and a linear type polishing apparatus. As an example, a general polishing apparatus having a surface plate (attached with a motor or the like whose rotation speed can be changed) to which a holder for holding an object to be polished such as a semiconductor wafer and a polishing pad are attached.

The polishing conditions are not limited, but for example, the rotation speed of the surface plate is preferably low rotation of 200 times / min or less so that the semiconductor wafer does not pop out, and the pressure applied to the semiconductor wafer is 1 kg so that no scratches are generated after polishing. / Cm ² or less is preferable. During polishing, a polishing agent is continuously supplied to the polishing pad by a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with the abrasive | polishing agent.

  Since CMP is performed with the surface state of the polishing pad always the same, a conditioning step of the polishing pad may be inserted before CMP. For example, in order to remove foreign substances such as particles adhering to the polished semiconductor wafer by performing polishing using a liquid containing at least water using a dresser with diamond particles, followed by a polishing step A wafer cleaning process including brush cleaning, megasonic cleaning for replacing abrasives with water, spin drying for removing water from the semiconductor wafer surface, and the like.

  The semiconductor wafer after polishing is preferably washed in running water and then dried after removing water droplets adhering to the semiconductor wafer using a spin dryer or the like.

  The polishing pad of the present invention is not only a silicon oxide film formed on a semiconductor wafer, but also a silicon oxide film formed on a wiring board having a predetermined wiring, glass, an inorganic insulating film such as silicon nitride, polysilicon, Al, Optical integrated circuits / lights composed of films mainly containing Cu, Ti, TiN, W, Ta, TaN, optical glass such as photomasks, lenses and prisms, inorganic conductive films such as ITO, glass and crystalline materials Switching element / optical waveguide, end face of optical fiber, optical single crystal such as scintillator, solid state laser single crystal, sapphire substrate for blue laser LED, semiconductor single crystal such as SiC, GaP, GaAS, glass substrate for magnetic disk, magnetic head, etc. Can be polished.

  The present invention is a method for polishing a semiconductor wafer, which is an object to be polished, by rotating the object to be polished against the polishing pad with a desired polishing pressure using the polishing pad of the present invention. In contrast, a direction intersecting the moving direction of the polishing pad by rotating the object to be polished while pressing it with a desired polishing pressure through the polishing slurry supplied together with the organic resin fine particles separated from the polishing pad by polishing. And polishing the surface of the object to be polished by the chemical and mechanical action of the slurry supplied between the surface of the polishing pad and the surface of the object to be polished. It is. Further, the present invention extends to a semiconductor device polished and manufactured by the above method.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. However, the present invention is not limited to these examples. The evaluation items in the disclosure and examples of the present invention were measured as follows.

Compression rate / compression recovery measurement method Cut into a circle (thickness: arbitrary) with a diameter of 7 mm as a sample for measurement of compression rate / compression recovery rate, in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5% 40 Let stand for hours. For the measurement, a thermal analysis measuring instrument TMA (SS6000 manufactured by SEIKO INSTRUMENTS) was used to measure the compression rate and the compression recovery rate. The calculation formulas for the compression rate and the compression recovery rate are as follows.

[In the formula, T1 is the thickness of the polishing layer when a stress load of 30 KPa (300 g / cm ² ) is maintained for 60 seconds from the unloaded state to the polishing layer, and T2 is 180 KPa (1800 g / cm ² ) from the state of T1. The thickness of the polishing layer when the stress load of 60 seconds is maintained. ]

[In the formula, T1 is the thickness of the polishing layer when a stress load of 30 KPa (300 g / cm ² ) is maintained for 60 seconds from the unloaded state to the polishing layer, and T2 is 180 KPa (1800 g / cm ² ) from the state of T1. The thickness of the polishing layer when the stress load of 60 seconds was held, and T3 was held for 60 seconds in the unloaded state from the state of T2, and then the stress load of 30 KPa (300 g / cm ² ) was held for 60 seconds. It is the polishing layer thickness at the time. ]

Specific gravity measurement 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).

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

SP value SP value (Solubility Parameter; solubility index) A. J. et al. The method proposed by Small [J. Appl. Chem. , 3, 71 (1953)].

Evaluation of Polishing Characteristics Using the prepared polishing pad, SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used as a polishing apparatus, and polishing characteristics were evaluated.

Polishing rate The polishing rate was evaluated by polishing about 0.5 μm of a 1-μm thick thermal oxide film formed on an 8-inch silicon wafer and calculating from this time. An interference type film thickness measuring device (manufactured by Otsuka Electronics Co., Ltd.) was used for measuring the thickness of the oxide film. As polishing conditions, silica slurry (SS12, manufactured by Cabot) was added as a slurry at a flow rate of 150 ml / min during polishing. The polishing load was 350 g / cm ² , the polishing platen rotation number was 35 rpm, and the wafer rotation number was 30 rpm.

The evaluation of uniformity was calculated from the following formula using the film thickness measured values at 25 arbitrary points of the wafer after polishing. Note that the smaller the uniformity value, the higher the uniformity of the wafer surface.

The scratch scratch was evaluated by measuring the number of striations of 0.2 μm or more on the surface of an oxide film of an 8 inch silicon wafer that had been polished using a wafer surface inspection device WM2500 manufactured by Topcon Corporation. The smaller this value, the less scratches and the better.

Example 1
In a fluorine-coated reaction container, 100 parts by weight of filtered polyether-based prepolymer (Uniroy, Adiprene L-325, NCO concentration: 2.22 meq / g), Teflon ^{(registered trademark)} resin fine particles (Daikin Industries, Ltd. ⁾ Fluororesin powder, particle size 2.0 μm, SP value 6.3) 10 parts by weight and filtered silicone-based nonionic surfactant (manufactured by Toray Dow Silicone, SH192) 3 parts by weight are mixed, and the temperature is 80 ° C. Adjusted. Using a fluorine-coated stirring blade, the mixture was vigorously stirred for about 4 minutes so that air 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., Ltd.) previously melted and filtered at 120 ° C. was added thereto (SP value of matrix resin 10). Thereafter, stirring was continued for about 1 minute, and the reaction solution was poured into a pan-type open mold coated with fluorine. When the fluidity of the reaction solution ceased, it was placed in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin fine foam block. This polyurethane resin microfoam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane resin microfoam 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 Koki Co., Ltd.) is used to make a groove width of 0.25 mm, groove pitch of 1.50 mm, and groove depth of 0.40 mm. Concentric grooves were processed. A double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape) was applied to the surface of the sheet opposite to the grooved surface using a laminator.

The physical properties of the produced polishing region were an average bubble diameter of 45 μm, a specific gravity of 0.86 g / cm ³ , a hardness of 53 degrees, a compression rate of 0.9%, a compression recovery rate of 65.0%, and a storage elastic modulus of 275 MPa.

Example 2
In a fluorine-coated reaction vessel, 100 parts by weight of filtered polyether-based prepolymer (Uniroy, Adiprene L-325, NCO concentration: 2.22 meq / g), polyethylene resin fine particles (Sumitomo Seika's flow beads) And 10 parts by weight of a particle size of 5.0 μm, SP value of 8.0) and 3 parts by weight of a filtered silicone-based nonionic surfactant (manufactured by Toray Dow Silicone, SH192) were mixed, and the temperature was adjusted to 80 ° C. Using a fluorine-coated stirring blade, the mixture was vigorously stirred for about 4 minutes so that air 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., Ltd.) previously melted and filtered at 120 ° C. was added thereto (SP value of matrix resin 10). Thereafter, stirring was continued for about 1 minute, and the reaction solution was poured into a pan-type open mold coated with fluorine. When the fluidity of the reaction solution ceased, it was placed in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin fine foam block. This polyurethane resin microfoam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane resin microfoam 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 Koki Co., Ltd.) is used to make a groove width of 0.25 mm, groove pitch of 1.50 mm, and groove depth of 0.40 mm. Concentric grooves were processed. A double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape) was applied to the surface of the sheet opposite to the grooved surface using a laminator.

The physical properties of the produced polishing region were an average bubble diameter of 45 μm, a specific gravity of 0.85 g / cm ³ , a hardness of 53 degrees, a compression rate of 0.8%, a compression recovery rate of 65.0%, and a storage elastic modulus of 275 MPa.

Comparative Example 1
In a fluorine-coated reaction vessel, 100 parts by weight of a filtered polyether-based prepolymer (Uniroy, Adiprene L-325, NCO concentration: 2.22 meq / g) and a filtered silicone-based nonionic surfactant (Toray 3 parts by weight of Dow Silicone, SH192) were mixed and the temperature was adjusted to 80 ° C. Using a fluorine-coated stirring blade, the mixture was vigorously stirred for about 4 minutes so that air 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., Ltd.) previously melted and filtered at 120 ° C. was added thereto (SP value of matrix resin 10). Thereafter, stirring was continued for about 1 minute, and the reaction solution was poured into a pan-type open mold coated with fluorine. When the fluidity of the reaction solution ceased, it was placed in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin fine foam block. This polyurethane resin microfoam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane resin microfoam 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 Koki Co., Ltd.) is used to make a groove width of 0.25 mm, groove pitch of 1.50 mm, and groove depth of 0.40 mm. Concentric grooves were processed. A double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape) was applied to the surface of the sheet opposite to the grooved surface using a laminator.

The physical properties of the produced polishing region were an average bubble diameter of 45 μm, a specific gravity of 0.87 g / cm ³ , a 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.

  A double-sided tape in which a cushion layer made of a corona-treated polyethylene foam (Toray Pef, thickness: 0.8 mm) is prepared on each of the polishing sheets obtained in Example 1, Example 2 and Comparative Example 1 above. It stuck together on the adhesion surface of the attached grinding | polishing area | region using the laminating machine. Further, a double-sided tape was bonded to the cushion layer surface to prepare each polishing pad, and the polishing characteristics were evaluated according to the above evaluation method. The results are shown in Table 1 below.

As is apparent from Table 1, the polishing pads of the present invention of Examples 1 and 2 are superior in polishing rate and uniformity to the polishing pad of Comparative Example 1, and can be polished with reduced scratches. I understood it.

Claims (11)

  A polishing pad used in chemical mechanical polishing for polishing a semiconductor wafer, wherein organic resin fine particles are dispersed in a matrix resin in a polishing region of the polishing pad, and the SP value of the organic resin fine particles is smaller than the SP value of the matrix resin. A polishing pad characterized by that.   The polishing pad according to claim 1, wherein the organic resin fine particles are insoluble in an aqueous slurry.   The polishing pad according to claim 1, wherein the organic resin fine particles have a particle diameter of 0.1 μm to 100 μm.   The polishing pad according to any one of claims 1 to 3, wherein the surface of the organic resin fine particles is formed of a negatively charged resin.   The polishing pad according to any one of claims 1 to 4, wherein at least a surface layer of the organic resin fine particles is made of at least one resin selected from the group consisting of a fluorine resin, a polyolefin resin, and a silicone resin.   The polishing pad according to claim 1, wherein the matrix resin is a polyurethane resin.   The polishing pad according to claim 6, wherein the polyurethane resin is a fine foam. The polishing pad according to claim 7, wherein the fine foam has a specific gravity of 0.5 to 1.0 g / cm ³ .   The polishing pad according to claim 7 or 8, wherein the fine foam has a hardness of 45 to 65 degrees.   The polishing pad according to any one of claims 7 to 9, wherein the fine foam has a compression ratio of 0.5 to 5.0%. A method for polishing a semiconductor wafer using the polishing pad according to claim 1.