JP4625252B2 - Polishing pad for CMP and polishing method using the same - Google Patents

Description

  The present invention relates to a CMP polishing pad used when planarizing unevenness of an object to be polished such as a semiconductor wafer by a chemical mechanical polishing (chemical mechanical polishing or CMP) method and a polishing method using the polishing pad.

In recent years, miniaturization and high integration of semiconductor integrated circuits have rapidly evolved, and it has become necessary to perform fine processing, and devices have become complicated structures and become three-dimensional.
Miniaturization is an advance in microfabrication technology in the manufacturing process of a semiconductor device, particularly in a lithography process, which is a technique for transferring a circuit pattern to a photosensitive organic film (photoresist) coated on a wafer surface using light. It has been achieved by increasing the resolution. Specifically, light sources used in the lithography process have been shortened, and techniques for exposing using these short wavelength light sources have been developed.
A method is being studied in which the difference in height of the device structure is reduced as much as possible to compensate for the lack of depth of focus and to ensure the resolution without causing fine pattern defocusing.

  Therefore, as a method for flattening the height difference of the device structure, a CMP method that applies mirror processing of a silicon wafer has been recently adopted. In this method, a polishing plate supported by a rotating polishing plate rotating shaft and having a polishing pad bonded to the surface, a diamond powder or the like electrodeposited on a metal plate, a dresser for conspicuous polishing pad surface, an interlayer A polishing slurry supply apparatus having a carrier that holds a polishing target (hereinafter referred to as a wafer) on which a polishing target layer such as an insulating film is formed by a wafer backing film, and a polishing slurry supply nozzle that supplies the polishing slurry onto the polishing pad. A device generally composed of

For example, in the CMP method, after dressing (grinding) the polishing pad with a dresser, the polishing plate rotating shaft and the carrier rotating shaft are rotated, and the polishing slurry is supplied from the polishing slurry supply nozzle to the central portion of the polishing pad while polishing. The wafer is polished by pressing the wafer onto the polishing pad by the pressure adjusting mechanism.
In such a CMP method, there are problems that micro scratches are generated on the surface to be polished, and polishing is not performed uniformly because the polishing rate is different within the surface to be polished.

In order to suppress the generation of micro scratches, polishing pad scraping scraps, dresser diamonds, interlayer films, wafer debris scraps and polished polishing slurries generated during dressing of the polishing pad (hereinafter collectively referred to as these) (Also referred to as impurities) must be discharged out of the polishing pad.
In the conventional CMP apparatus, a measure is taken such that the polishing slurry is sufficiently poured into the central portion of the polishing pad without any interruption during the polishing operation, and impurities are removed or pushed out of the polishing pad by this polishing slurry.

  When the polishing slurry is supplied in this way to polish the wafer, the polishing slurry is pushed out by the centrifugal force generated by the rotation of the polishing pad and the wafer being pressed against the polishing pad, and most of the polishing slurry is not directly contributed to the polishing. Therefore, an expensive polishing slurry is consumed excessively.

  In order to solve these problems, a polishing pad has been proposed as a conventional technique in which concentric grooves are formed on the surface of the polishing pad, and the outer periphery of the groove is inclined in the circumferential direction (see Patent Document 1). . In the polishing pad disclosed in Patent Document 1, although it is effective to discharge “impurities” such as polishing slurry to the outside of the polishing pad, it is not possible to control excessive consumption of the slurry, and polishing is performed within the surface to be polished. The rate cannot be made uniform.

In order to make the polishing rate uniform within the surface to be polished, there has been proposed a polishing pad in which a plurality of grooves are formed in the center portion in the radial direction of the polishing pad (see Patent Document 2). However, the polishing pad disclosed in Patent Document 2 is provided with a large number of through-holes, making it difficult to hold an appropriate slurry between the surface to be polished and the polishing pad, resulting in unstable polishing.
Japanese Patent Laid-Open No. 2003-165049 JP 2002-160153 A

  The present invention solves the above-mentioned conventional problems, and the object of the present invention is to appropriately hold the slurry between the surface to be polished and the polishing pad so that there is no excessive consumption of the slurry and the surface to be polished. An object of the present invention is to provide a polishing pad for CMP which can make the polishing rate uniform.

  The present invention provides a polishing pad for CMP having different depth grooves in which a small depth portion and a large depth portion are formed in the same groove on the polishing surface, thereby achieving the above object.

  In polishing of a semiconductor wafer or the like using the polishing pad of the present invention, it simultaneously solves problems such as excessive consumption of slurry and non-uniform polishing rate, and between the surface to be polished and the polishing pad. The slurry is appropriately held, and there is no excessive consumption of the slurry, which is particularly effective in improving the in-plane uniformity after polishing of the object to be polished, and is extremely effective in the production of chemical mechanical polishing such as semiconductor wafers.

The polishing pad is a layered member that polishes the object to be polished. The polishing pad functions as a carrier for the polishing slurry when polishing, and has a polishing surface that contacts and rubs the object to be polished. The polishing surface preferably has a surface shape or surface structure suitable for holding and renewing the polishing slurry. The polishing pad of the present invention has a different depth groove in which a small depth portion and a large depth portion are formed on the polishing surface.
The different depth grooves may be formed radially or spirally on the polishing surface, and the number thereof is not particularly limited. The different depth grooves may be formed consistently from the center to the outer peripheral part, or may be formed consistently from the part off the central part to the outer peripheral part. The different depth grooves may be formed starting from the center of the pad, but may be formed eccentrically by shifting the center point. The change in the groove depth of the different depth groove may be abrupt (see FIG. 1) or may be stepwise.

  The number of different depth grooves is not particularly limited, but the average ratio of the opening area of the groove in the polishing pad surface is preferably 1 to 50%, more preferably 2 to 20%, and such a value. The groove width and number can be selected so that

  The groove forming method is not particularly limited. For example, a method of machine cutting using a jig such as a tool of a predetermined size, pouring resin into a mold having a predetermined surface shape, and curing the resin. A method of manufacturing by pressing, a method of pressing and manufacturing a resin with a press plate having a predetermined surface shape, a method of manufacturing using photolithography, a method of manufacturing using a printing technique, a laser beam using a carbon dioxide laser, etc. For example.

  FIG. 1 is a plan view and a cross-sectional view of AA ′ of a polishing pad according to an embodiment of the present invention. In the plan view, different depth grooves 2 are provided radially from the center of the polishing pad on the polishing surface of the polishing pad 1. In the cross-sectional view, inside the different depth groove 2, a large depth portion is formed at the center portion of the polishing pad and a small depth portion is formed at the peripheral portion of the polishing pad. Here, the center portion of the polishing pad refers to a region B close to the center of the polishing pad on the polishing surface. Region E, which is close to the center of the polishing pad and where no grooves are shown, does not substantially exhibit polishing action and need not be included in the polishing surface. Accordingly, the region E is also excluded from the central portion. The peripheral portion of the polishing pad refers to a region C in the polishing surface close to the periphery of the polishing pad.

  It is preferable that the dimensions of the central portion B and the peripheral portion C are appropriately formed so that the central portion B does not exceed the size of the object to be polished at the position where the object to be polished and the polishing pad are brought into contact with and polished. As a result, it is possible to prevent the outer edge portion of the wafer or the like from being polished and the central portion from being hard to be polished, and in-plane polishing unevenness of the wafer or the like does not occur.

  FIG. 2 is a plan view and a cross-sectional view of AA ′ of a polishing pad according to another embodiment of the present invention. In the plan view, different depth grooves 2 are provided radially from the center of the polishing pad on the polishing surface of the polishing pad 1. In the cross-sectional view, inside the different depth groove 2, a small depth portion is formed in the center portion B of the polishing pad, a small depth portion is formed in the peripheral portion C, and a large depth portion is formed in the intermediate portion D sandwiched between both. .

  The dimensions of the central part B, the peripheral part C, and the intermediate part D are the same as described above, so that the intermediate part D does not exceed the dimension of the object to be polished at the position where the object to be polished and the polishing pad are abutted and polished. Preferably, it is formed appropriately.

  Furthermore, DH / DA is preferably 2 or more, where DH is the depth of the large depth portion and DA is the depth of the small depth portion. If this value is less than 2, the slurry is not properly held between the surface to be polished and the polishing pad, and excess consumption of the slurry cannot be controlled, and the polishing rate is made uniform within the surface to be polished. I can't do that either.

Although the different depth groove | channel in this invention is not specifically limited in the width and depth, What is necessary is just to have a width | variety of about 0.08 mm-5.0 mm, and a depth of about 0.2 mm-3.0 mm. From these ranges, an appropriate material may be selected according to the object to be polished, the polishing method and the polishing conditions.
In the present invention, it is preferable that the groove width is the same and only the depth is changed, so that the polishing rate can be easily controlled, and the convenience in manufacturing a polishing pad such as groove processing is excellent.

As a polishing pad in the present invention, at least two layers of a conventional single layer type pad or a surface hard layer that comes into contact with an object to be polished such as a wafer and an elastic support layer positioned between the surface hard layer and the platen are used. The laminated polishing pad may be a laminated polishing pad such as a multilayer polishing pad formed by stacking other layers. From the viewpoint of production and performance, those having at least two elastic support layers located between the hard surface layer and the platen are preferable.
Thus, the present invention is not limited to a single-layer or multi-layer polishing pad.

In the laminated polishing pad, the surface hard layer and the elastic support layer are roughly divided. The hardness of the hard surface layer (measured according to JIS K6253-1997, Asker D type hardness meter manufactured by Kobunshi Keiki Co., Ltd.) is preferably 45-65. When the hardness is less than 45 degrees, the planarity (flatness) of the object to be polished is deteriorated. When the hardness is more than 65 degrees, the planarity is good, but the uniformity (uniformity) of the object to be polished is deteriorated. End up. In the Asker A hardness of the elastic support layer (measured according to JIS K6253-1997, Asker A type hardness meter manufactured by Kobunshi Keiki Co., Ltd.), it is preferably 25 to 100, more preferably 30 to 85.
The thickness of the surface hard layer is preferably 0.5 to 5.0 mm, more preferably 0.8 to 4.0 mm, and the thickness of the elastic support layer is preferably 0.3 to 3.0 mm, more preferably 0. .6 to 2.0 mm.

In a single-layer polishing pad, the thickness (pad thickness) is about 0.5 to 5.0 mm, and the material is appropriately selected from materials used for the surface hard layer and the elastic support layer, respectively. It may be a thing.
In the laminated polishing pad, the surface hard layer is preferably an acrylate-based photocurable resin, polyurethane such as non-foamed polyurethane or foamed polyurethane, and the elastic support layer is preferably polyethylene foam, polyurethane foam, polyester nonwoven fabric, or the like. It is not a thing. When the surface hard 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 hardness range is satisfied.
In the present invention, a polyurethane foam resin is a particularly preferable member of the hard surface layer (the surface of the polishing layer).

  When a polyurethane resin is foamed, the foaming method can be shared by foaming with a chemical foaming agent, foaming to incorporate mechanical foam, and mixing of a hollow body or a precursor that becomes a hollow body by heat. It may be. By these foaming methods, a fine foam used for the polishing pad in the present invention is obtained.

  The polyurethane resin is composed of an isocyanate-terminated urethane prepolymer and an organic diamine compound, and the isocyanate-terminated urethane prepolymer is composed of a polyisocyanate, a high molecular polyol, and a low molecular polyol. Examples of the polyisocyanate include 2,4- and / or 2,6-toluene diisocyanate, 2,2′-, 2,4′- and / or 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate. Neat, 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), bi -(4-isocyanatocyclohexyl) methane (= hydrogenated MDI), 2- and 4-isocyanatocyclohexyl-2'-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanatomethyl)- And 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. Polyethers and polycarbonates having good hydrolyzability are preferred, and polyethers are particularly preferred from the viewpoint of cost 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. Is mentioned. Starting compounds having reactive hydrogen atoms include water, bisphenol A and the divalent alcohols described above to produce polyester polyols.

  Further, as the polycarbonate having a hydroxy group, for example, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene Diols such as glycol and / or polytetramethylene glycol and phosgene, diallyl carbonate (eg diphenyl carbonate) or cyclic carbonate (eg propylene carbonate) And a reaction product with G). Examples of the polyester polyol include a reaction product of a divalent alcohol and a dibasic carboxylic acid. In order to improve hydrolysis resistance, a longer distance between ester bonds is preferable. A combination of long chain components is desirable.

  The divalent alcohol is not particularly limited, but examples thereof include ethylene glycol, 1,3- and 1,2-propylene glycol, 1,4- and 1,3- and 2,3-butylene glycol. -L, 1,6-hexane glycol, 1,8-octanediol, neopentyl glycol, cyclohexane dimethanol, 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.

  As the dibasic carboxylic acid, there are 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 the dihydric alcohol used to produce the polyester polyol described above. The low molecular polyol of the present invention includes diethylene glycol, 1,3-butylene glycol, 3 It is preferable to use any one of methyl-1,5-pentanediol and 1,6-hexamethylene glycol or a mixture thereof.

  The isocyanate component is appropriately selected according to the pot life required at the time of cast molding, 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-toluene diisocyanate, 2,2′-, 2,4′- and / or 4,4′-diphenylmethane diisocyanate, 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. 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.

  The average cell diameter of the polishing region made of the fine foam in the present invention is preferably 70 μm or less. A deviation from this range is not preferable because planarity deteriorates.

The specific gravity of the polishing region made of the fine foam in the present invention is preferably 0.5 to 1.0 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 (flatness) of the object to be polished deteriorates, and when the specific gravity is greater than 1.0 g / cm ³ , the polishing region Although the number of fine bubbles on the surface tends to be small and planarity is good, it is not preferable because the polishing rate is deteriorated.

  The hardness of the polishing region made of the fine foam in the present invention is preferably 45 to 65 by an Asker D hardness meter. When the D hardness is less than 45 degrees, the planarity (flatness) of the object to be polished is deteriorated. When it is greater than 65 degrees, the planarity is good, but the uniformity (uniformity) of the object to be polished is deteriorated. End up.

  The compressibility of the polishing region made of the fine foam in the present invention is preferably 0.5 to 5.0%. By having a compression ratio in the range, it is possible to achieve both planarity and uniformity.

  In the present invention, the compression recovery rate of the polishing region made of the fine foam is preferably 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. .

  In the present invention, the storage elastic modulus of the polishing region made of the fine foam is preferably 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.

  In the polishing method of the present invention, the CMP method is performed using the polishing pad of the present invention. In other words, while supplying a polishing slurry to the surface of the polishing pad, the object to be polished is rotated while being pressed with a desired polishing pressure, and is swung in a direction intersecting with the moving direction of the polishing pad. The surface of the object to be polished is 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.

For example, the CMP polishing pad described above is fixed to the platen of the polishing apparatus,
Fix the object to be polished to the polishing table support so that it faces the polishing surface of the polishing pad,
Contacting the object to be polished with the polishing surface of the polishing pad; and polishing while supplying a polishing slurry;
Should be done. By polishing by such a polishing method, a semiconductor device can be obtained.

  However, when the object to be polished is brought into contact with the polishing surface of the polishing pad, the small depth region hits the outer peripheral portion of the object to be polished 3 on the polishing surface of the polishing pad, and the large depth region is the center of the object to be polished 3. It is necessary to adjust the position of the object to be polished so that It is considered that the large depth portion of the different depth groove has a larger amount of polishing slurry than the small depth portion, and the large depth region of the polishing surface has higher polishing ability than the small depth region. For this reason, in general, by applying a central portion of an object to be polished, which has a low polishing rate in the CMP method, to a large depth region where the polishing ability is high, in-plane uniformity after polishing of the object to be polished can be achieved.

  When the object to be polished is brought into contact with the polishing pad, the preferred positional relationship between the two is shown in FIGS. The non-abrasive body 3 is swung laterally with reference to the position shown here. In FIG. 1, the outer peripheral part F of the to-be-polished body 3 is applied to the small depth region. The length of the outer peripheral portion F is 25% or less, preferably 15% or less of the diameter of the object to be polished 3. In FIG. 2, the center of the object to be polished 3 is located at the center of the deep groove. The dimension D is substantially the same as the diameter of the object 3 to be polished. In this case, by swinging the object to be polished 3, the substantially small depth region hits the outer peripheral portion of the object to be polished 3, and the large depth region hits the center of the object to be polished 3. The dimension D may be smaller than the diameter of the object to be polished 3.

  When a workpiece having a diameter of 20 cm is polished with a polishing pad having a diameter of 61 cm, the size of the peripheral portion F shown in FIG. 1 is adjusted to 5 cm or less, preferably 2.5 cm or less. Further, the dimension of the remaining portion G of the diameter of the object to be polished 3 is adjusted to 15 cm or more, preferably 17.5 cm or more. In this case, the dimension D of the deep region shown in FIG. 2 is 16 to 20 cm, preferably 18 to 20 cm.

Examples and the like that specifically show the effects of the present invention will be described below. The evaluation items in Examples and the like were measured as follows.
Specific gravity measuring method It carried out based on JISZ8807-1976. A sample cut into a 4 cm × 8.5 cm strip (thickness: arbitrary) was used as a sample for measuring the specific gravity, and allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. A hydrometer (manufactured by Sartorius) was used for the measurement.

Hardness measuring method Measured according to JIS K6253-1997. A sample cut into a size of 2 cm × 2 cm (thickness: arbitrary) was used as a sample for hardness measurement, and allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 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 (Asker D-type hardness meter manufactured by Kobunshi Keiki Co., Ltd.).

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, and 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. This is the thickness of the polishing layer when the stress load is maintained for 60 seconds. ]

[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. ]

Evaluation of polishing characteristics SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used as a polishing apparatus, and polishing characteristics were evaluated using the prepared polishing pads. The polishing rate was calculated from the time obtained by polishing about 0.5 μm of a 1-μm thermal oxide film formed on an 8-inch silicon wafer. 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 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. Further, the rocking speed was 1 mm / sec. The rocking distance was 20 mm.
Further, the in-plane uniformity was calculated by the following formula from film thickness measurement values at arbitrary 25 points on the wafer. Note that the smaller the in-plane uniformity value, the higher the uniformity of the wafer surface.

  In a fluorine-coated reaction vessel, 100 parts by weight of a filtered polyether-based prepolymer (Uniroy, Adiprene L-325, isocyanate group concentration: 2.22 meq / g), and a filtered silicone-based surfactant (Toray 3 parts by weight of SH Dou Silicone, SH192) were mixed, and the reaction temperature was adjusted to 80 ° C. Using a fluorine-coated stirrer, 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. Thereto was added 26 parts by weight of 4,4'-methylenebis (o-chloroaniline) (Ihara Chemical Co., Iharacamine MT), which was previously melted and filtered at a temperature of 120 ° C. After stirring for about 1 minute, the reaction solution was poured into a pan-type open mold coated with fluorine. When the fluidity of the reaction solution disappeared, it was placed in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin foam block.

The polyurethane resin foam block was sliced using a band saw type slicer (Fecken) to obtain a sheet-like polyurethane foam. Next, this sheet was subjected to surface buffing to a predetermined thickness using a buffing machine (manufactured by Amitech Co., Ltd.) to obtain a sheet with adjusted thickness accuracy (sheet thickness: 1.27 mm). The average bubble diameter on the grooved surface of this sheet was 45 μm, specific gravity 0.86 g / cm ³ , Asker D hardness 53 degrees, compression rate 1.0%, compression recovery rate 65.0%, and storage elastic modulus 275 MPa. .

  The buffed sheet is punched out to a diameter of 61 cm, and a groove width (2 mm) is formed from the outer periphery of the circle to the outer periphery of the pad, leaving a 2 cm circle on the surface using a groove processing machine (manufactured by Toho Kouki Co., Ltd.). Groove processing was performed on 16 radial grooves with an angle of 22.5 degrees between the grooves. With respect to the groove depth, all the grooves were processed with 0.3 mm from the outer periphery to ¼ of the portion in contact with the wafer in a state without rocking, and other portions with 0.8 mm (see FIG. 1). Using a laminator on the opposite side of the grooved surface of this sheet, a double-sided tape (Sekisui Chemical Co., Ltd., double tack tape) was applied, and a corona-treated cushion sheet (Toray Industries, polyethylene foam, Torepefu) , 0.8 mm thick) was buffed and bonded to the sheet using a laminating machine. Further, a double-sided tape was attached to the other surface of the cushion sheet using a laminator to prepare a polishing pad.

  Using a grooving machine (manufactured by Toho Koki Co., Ltd.), leaving a 2 cm circle on the surface, from the outer periphery of the circle to the outer periphery of the pad, the groove width is 2 mm, and the angle between the grooves is 22.5 degrees 16 Groove processing of radial grooves was performed. With respect to the groove depth, all the grooves were processed in the same manner as in Example 1 except that the wafer contact portion in a state without rocking was processed at 0.8 mm and the other portions were processed at 0.3 mm (see FIG. 2). A polishing pad was produced using the material and method. In this case, the portions 10 mm from the outer periphery of the wafer come into contact with the portions having a groove depth of 0.3 mm by the swing.

Comparative Example 1

  FIG. 3 is a plan view and a cross-sectional view of a conventional polishing pad. In the plan view, grooves 2 ′ are provided radially from the center of the polishing pad on the polishing surface of the polishing pad 1. In the cross-sectional view, the depth inside the groove 2 'is constant. A conventional polishing pad of the form shown in FIG. 3 was manufactured as follows.

  Using a grooving machine (manufactured by Toho Koki Co., Ltd.), leaving a 2 cm circle on the surface, from the outer periphery of the circle to the outer periphery of the pad, the groove width is 2 mm, and the angle between the grooves is 22.5 degrees. A polishing pad was produced by the same material and method as in Example 1 except that the radial grooves were processed and the groove depth was processed at a constant 0.6 mm. The polishing pads of Examples 1 and 2 and Comparative Example 1 were evaluated by the above method. The results are shown in Table 1.

FIG. 1 is a plan view and a cross-sectional view of AA ′ of a polishing pad according to an embodiment of the present invention. FIG. 2 is a plan view and a cross-sectional view of AA ′ of a polishing pad according to another embodiment of the present invention. FIG. 3 is a plan view and a cross-sectional view of a conventional polishing pad.

Explanation of symbols

1 ... polishing pad,
2 ... different depth groove,
3 ... Polished object.

Claims (5)

A different depth groove in which a small depth portion and a large depth portion are formed in the same groove is provided on the polishing surface, the small depth portion at the center of the polishing pad, the large depth portion at the intermediate portion, and the peripheral portion. the have a small depth portion is formed, the are different depth grooves are formed radially or spirally, Ri is abruptly or stepwise der changes of the different depth grooves of the groove depth, the groove forming method, grooving Using a machine cutting method using a machine, pouring a resin into a mold and curing it, a method of pressing and manufacturing a resin with a press plate, a method of manufacturing using photolithography, and a printing technique A polishing pad for CMP made of polyurethane selected from the group consisting of a production method and a production method by laser light .   The polishing pad for CMP according to claim 1, wherein DH / DA is 2 or more, where DH is a depth of the large depth portion and DA is a depth of the small depth portion. A step of fixing the CMP polishing pad according to claim 1 or 2 to a platen of a polishing apparatus;
Fixing the object to be polished to the support of the polishing apparatus so as to face the polishing surface of the polishing pad;
By swinging the object to be polished on the polishing surface of the polishing pad in a direction intersecting the moving direction of the polishing pad, the small depth region hits the outer periphery of the object to be polished, and the large depth region is the surface of the object to be polished. A step of bringing an object to be polished into contact with a polishing surface of a polishing pad so as to hit the center; and a step of polishing while supplying a polishing slurry;
A polishing method comprising:   The polishing method according to claim 3, wherein the object to be polished is a semiconductor wafer.   A semiconductor device manufactured by the method according to claim 4.

Images