JP2005183711A - Polishing pad, method of polishing, semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad particularly effective to improve the proper value maintenance of a polishing rate and in uniformity in a surface after polishing a material to be polished and extremely effective in manufacturing such as the chemical mechanical polishing, etc. of a semiconductor wafer, etc., by solving simultaneously subjects such as the unevenness or decreases of the polishing rate, the large unevenness of an amount of polishing in the surface of a water, the excessive consumption of polishing slurry, and further unable to hold suitable slurry between the material to be polished and the polishing pad, and to provide a method of polishing. <P>SOLUTION: The polishing pad 1 includes a plurality of parallel groove groups made of substantially straight line grooves parallel to each other in the polishing surface. At least the groove 2 has different groove depths in the one and same groove. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing pad used for polishing an object to be polished and a polishing method using the same, and in particular, in a semiconductor device manufacturing process, such as an interlayer insulating film by CMP (chemical mechanical polishing or chemical mechanical polishing). The present invention relates to a polishing pad used when performing a planarization process, a polishing method using the polishing pad, a semiconductor device manufacturing method, and a semiconductor device obtained by the manufacturing method.

  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 that 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, a technique for performing exposure using a light source having a shorter wavelength in a lithography process has been developed. In addition, 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 reliably resolve a fine pattern without causing a defocus.

  Therefore, as a method for flattening the difference in height of the device structure, a CMP method that applies mirror processing of a silicon wafer has been recently adopted. This apparatus is supported by a rotating polishing plate rotating shaft and has a polishing pad on the surface. A polishing plate to which a surface of the polishing pad is made conspicuous, and a polishing object layer (such as an interlayer insulating film) formed with diamond powder or the like formed by electrodeposition on a metal plate. (Hereinafter, referred to as a wafer) by a wafer backing film and a polishing slurry supply device having a polishing slurry supply nozzle for supplying the polishing slurry onto the polishing pad.

  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 microscratches are generated in a layer to be polished such as an insulating film of the wafer, a polishing rate varies, and a polishing amount varies widely within the wafer surface.

  In order to suppress the occurrence of micro-scratch, polishing pad scraping scraps, dresser diamonds, interlayer films, wafer debris 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 such a conventional CMP apparatus, measures are 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. Thus, 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 in excess.

  In order to solve these problems, a polishing pad (see Patent Document 1) or a plurality of polishing pads formed with a lattice-like (a plurality of linearly parallel groove groups) in a state where grooves are opened on the outer peripheral portion of the pad on the polishing pad surface. A polishing pad (see Patent Document 2) having a polygonal protrusion formed by a group of linearly parallel grooves has been proposed.

  In the polishing pad disclosed in Patent Document 1, a groove having a width of about 1 to 5 mm and a depth of about 0.5 to 2.5 mm is cut and formed at an interval of about 10 to 100 mm, so that the entire polishing pad has a sufficient polishing slurry. However, it is difficult to maintain the polishing rate, suppress excessive polishing slurry consumption, and reduce the amount of polishing in the wafer surface at the same time. .

  Also, in the polishing pad disclosed in Patent Document 2, in order to improve the flatness and the like, a polygonal protrusion formed by a plurality of linearly parallel groove groups is formed on the polishing pad surface. Even if the discharge is effective, it has been difficult to simultaneously maintain the polishing rate, suppress excessive polishing slurry consumption, and suppress variations in the polishing amount in the wafer surface.

In addition, Patent Documents 3 to 6 disclose similar polishing pads, but all maintain the polishing rate, and at the same time, suppress excessive consumption of polishing slurry and suppress variation in the amount of polishing in the wafer surface. It was difficult to solve.
Japanese Patent Application Laid-Open No. 08-216029 Japanese Patent Laid-Open No. 10-071561 JP-A-10-315119 JP 2000-117620 A JP 2001-001255 A Japanese Patent Laid-Open No. 2001-079755

  The present invention relates to a polishing pad used when performing planarization processing of an interlayer insulating film or the like by CMP in a manufacturing process of a semiconductor device and the like, and a polishing method using the polishing pad. It is intended to simultaneously solve problems such as large variations in the surface, excessive consumption of polishing slurry, and inability to hold an appropriate slurry between the object to be polished and the polishing pad.

  The present invention solves the above-mentioned problems at the same time, and provides, for example, a polishing pad used when performing planarization processing of an interlayer insulating film or the like by CMP in a semiconductor device manufacturing process and the like, and an efficient polishing method using this polishing pad. Is. That is, the present invention is a polishing pad having a plurality of parallel groove groups consisting of substantially straight grooves parallel to each other in the polishing surface, wherein at least one of the grooves has different groove depths in the same groove. A polishing pad having a plurality of parallel groove groups consisting of substantially straight grooves parallel to each other, characterized by being deep grooves.

Furthermore, in order to implement this invention suitably,
The plurality of parallel groove groups are parallel groove groups orthogonal to each other;
The groove depth in the different depth groove is large at the center and the middle part of the polishing pad, and small at the outer peripheral part,
The groove depth in the different depth groove is small at the center portion of the polishing pad, large at the intermediate portion, and small at the outer peripheral portion,
It is preferable that DH / DA is 2 or more when the maximum groove depth in the different depth grooves is DH and the minimum groove depth is DA.

  As another aspect of the present invention, a polishing method for polishing a body to be polished using the polishing pad, a manufacturing method for a semiconductor device characterized by manufacturing using the polishing method, and the manufacturing method described above There is a semiconductor device characterized by being manufactured.

  The polishing pad according to the present invention is preferably used for a polishing pad used when performing planarization processing of an object to be polished by CMP, and has a large or small polishing rate and a large amount of polishing in a wafer surface. It is intended to solve problems such as excessive consumption of polishing slurry, and inability to hold an appropriate slurry between the object to be polished and the polishing pad at the same time. ), A polishing pad in which a plurality of parallel groove groups consisting of substantially straight grooves parallel to each other are formed, wherein at least one of the grooves is a groove group having different depths in the same groove. Is formed. The effect of the present invention cannot be obtained at the same time when the lattice-shaped grooves having the same depth are formed in the polishing pad surface.

  In polishing of a semiconductor wafer or the like using the polishing pad of the present invention, the polishing rate varies or decreases, the variation in the polishing amount in the wafer surface, the excessive consumption of the polishing slurry, and the object to be polished and the polishing pad It is particularly effective for simultaneously solving the problems such as inability to maintain an appropriate slurry between the two, maintaining a constant polishing rate, and improving in-plane uniformity after polishing of the object to be polished. It is extremely effective in production.

  The number of parallel grooves in the present invention is a plurality of parallel grooves composed of substantially straight grooves parallel to each other, and at least one of the grooves is a different depth groove having different groove depths in the same groove. Although it is not particularly limited, it can be selected and formed as appropriate, but at least 10 or more are preferable, and the substantially straight groove may be a straight line as literally and a parallel line having a slight meander ( 1-A and FIG. 2-A). Further, “parallel to each other” should be understood as including not only those where adjacent grooves are strictly parallel but also those that do not intersect each other within the polishing surface of the polishing pad. Furthermore, the change of the groove depth of the different depth groove may be abrupt or stepwise.

  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.

  In the present invention, a plurality of parallel groove groups consisting of substantially straight grooves parallel to each other, wherein at least one of the grooves is a different depth groove having different groove depths in the same groove, The number is not particularly limited, but the average ratio of the opening area of the groove in the polishing surface of the polishing pad to the sum of the opening and the other planar area is preferably 1 to 50%, more Preferably it is 3 to 30%.

  The polishing pad in the present invention is a plurality of parallel groove groups consisting of substantially straight grooves parallel to each other on a polishing surface that is a surface layer of a polishing pad that comes into contact with an object to be polished such as a wafer. 1 is a polishing pad having grooves in a parallel groove group that are different depth grooves having different groove depths in the same groove, and in the grooves formed in the polishing surface, all of them are different depth grooves In addition, at least one of them may be a groove at a different depth, and may be appropriately selected and implemented according to the properties of the wafer as the object to be polished, the polishing conditions, and the polishing method.

  As described above, in the polishing pad of the present invention, the groove depth in the different depth groove is preferably large at the central portion and the intermediate portion of the polishing pad and small at the outer peripheral portion, and small at the central portion of the polishing pad. More preferably, it is formed large in the intermediate part and small in the outer peripheral part. In this case, it is preferable that the portion where the groove depth is large does not exceed the size of the polishing body at the position where the polishing object such as a wafer is in contact with the polishing pad and polished. Therefore, it is possible to prevent the outer edge portion of the wafer or the like from being polished and the central portion from being difficult to be polished. In the polishing pad, the central portion, the intermediate portion, and the outer peripheral portion indicate that the a zone in FIG. 1 is the central portion, the b zone is the intermediate portion, and the c zone is the outer peripheral portion. Is included in the circular portion including 4/10 of the pad radius, the b zone includes a ring portion including 1/2 of the pad radius, and the c zone includes 9/10 or more of the pad radius and includes 6/10 of the pad radius. There is no ring part.

  Furthermore, a polishing pad in which DH / DA is 2 or more when the maximum depth of the groove in the different depth groove is DH and the minimum depth of the groove is DA is a preferred embodiment of the present invention. The DH / DA is preferably 2 to 4, more preferably 2 to 3. When the DH / DA is less than 2, the amount of slurry consumed increases, the polishing rate decreases, and the in-plane uniformity deteriorates.

  The grooves of the parallel groove group in the present invention are not particularly limited in width and depth, but have a width of about 0.2 mm to 5.0 mm and a depth of about 0.2 mm to 4.0 mm. From these ranges, it may be selected as appropriate in accordance with the object to be polished, the polishing method and the polishing conditions. In the present invention, the groove width is preferably the same, and only the depth is changed. In this case, the polishing rate can be easily controlled, and the convenience in manufacturing is excellent.

  The polishing pad in the present invention may be a single layer type pad generally used in the past, or a hard surface layer that comes into contact with an object to be polished such as a wafer and an elastic support positioned between the hard surface layer and the platen. It may be a laminated pad having at least two layers, or may be a laminated polishing pad such as a multilayer polishing pad in which other layers are stacked. In view of production and performance, those having at least two elastic support layers located between the hard surface layer and the platen (surface plate) are preferable. Thus, the present invention is not limited to a single-layer or multi-layer polishing pad.

  In the laminated polishing pad, a hard surface layer and an elastic support layer are roughly divided and formed according to the hardness of the hard surface layer (according to JIS K6253-1997. 2 cm × 2 cm (thickness: A sample cut into a size of (optional) was used as a sample for hardness measurement, and 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 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. The hardness of the elastic support layer (according to JIS K6253-1997, Asker A hardness meter manufactured by Kobunshi Keiki Co., Ltd.) is preferably 25 to 100, more preferably 30 to 85. Further, the thickness of the hard surface layer is preferably 0.2 to 4 mm, more preferably 0.8 to 3.0 mm, and the thickness of the elastic support layer is preferably 0.5 to 2.5 mm, more preferably 0. It is desirable that the thickness is 8 to 2.0 mm.

  In the single-layer polishing pad, the thickness is about 1.0 to 5.0 mm, and the material may be appropriately selected from materials used for the hard surface layer and the elastic support layer, respectively.

  In the laminated polishing pad, the hard surface 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 non-woven fabric, or the like. It is not a thing. 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 hardness range is satisfied. In the present invention, a particularly preferred hard surface layer material is a foamed polyurethane resin.

  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. There 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-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. Examples of the starting compound having a reactive hydrogen atom include water, bisphenol A, and a dihydric alcohol for producing a polyester polyol as described below.

  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. In order to improve hydrolysis resistance, a longer distance between ester bonds is preferable. A combination is desirable.

  Although it does not specifically limit as dihydric alcohol, 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-pentane Examples include diol, 2,2,4-trimethyl-1,3-pentanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, and dibutylene glycol.

  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 dihydric alcohols used for producing the above-described polyester polyol. The low molecular polyol of the present invention includes diethylene glycol, 1,3-butylene glycol, 3-methyl-1,5. It is preferable to use any one of 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. Therefore, the isocyanate component is used alone or as a mixture of two or more. 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 ), Bis- (4-isocyanatocyclohexyl) methane (= hydrogenated MDI), 2- and 4-isocyanatocyclohexyl-2′-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanato) Methyl) -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-amino) Phenylthio) 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 decrease 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 above 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.

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 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 measurement was performed in accordance with 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 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 (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, 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. ]

Groove Depth Measurement Method Digital depth gauge DMD-210 (manufactured by Teclock Co., Ltd.) was used to measure the groove depth. When the digital depth gauge is used, the groove depth can be measured without sampling. The groove depth at three points every 5 mm was measured, and the average value was defined as the groove depth.

  Using the polishing pad of the present invention, 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 intersects the moving direction of the polishing pad. The object to be polished is a semiconductor by a method of 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. The polishing method is a device, and the polishing pad of the present invention is most effective in polishing this semiconductor. Further, the present invention extends to a semiconductor device polished and manufactured by the above method.

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

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

(2) In-plane uniformity In-plane uniformity was calculated from the film thickness measured values at arbitrary 25 points on the wafer by the following formula. Note that the smaller the in-plane uniformity value, the higher the uniformity of the wafer surface.

Example 1
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 /), and a filtered silicone-based surfactant (Toray Dow) 3 parts by weight manufactured by Silicone Corporation (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) (made by Ihara Chemical Co., Ltd., Iharacamine MT) which was previously melted at a temperature of 120 ° C. and filtered. 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 (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 was punched out to a diameter of 61 cm, and (groove) in the form of a lattice with a groove width of 2 mm and a groove pitch of 15 mm was performed on the surface using a groove processing machine (manufactured by Toho Steel Co., Ltd.). Regarding the groove depth, the outer peripheral part of the polishing pad (see FIGS. 1A and 1B, the outer part of the c zone in FIG. 1A from the outer part 70 mm away from the outer part (the outer part from 235 mm from the center)) is 0.3 mm. The central part was processed at 0.8 mm (see FIGS. 1A and 1B, a part other than the c zone which is the a and b zones in FIG. 1A). 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) and buffed and bonded to the sheet using a laminator. Further, a double-sided tape was attached to the other side of the cushion sheet using a laminator to prepare a polishing pad.

Example 2
Using the same sheet as in Example 1, a groove processing machine (manufactured by Toho Koki Co., Ltd.) was used to perform orthogonal grid-like groove processing with a groove width of 2 mm and a groove pitch of 15 mm on the surface, The depth of the contact portion is 0.8 mm (see FIGS. 1A and 1C, the b zone in FIG. 1A, the inner portion from 70 mm from the outer periphery and the outer portion from 70 mm from the center), and the central portion and outer peripheral portion of the polishing pad Was processed at a depth of 0.3 mm (see FIGS. 1A and 1C, portions other than the b zone, which are the a and c zones in FIG. 1A), and a polishing pad was produced in the same manner as in Example 1. .

Comparative Example 1
Using the same sheet as in Example 1, a groove processing machine (manufactured by Toho Steel Machine Co., Ltd.) is used to perform a grid-like groove processing with a groove width of 2 mm and a groove pitch of 15 mm on the surface, and the groove depth is constant 0.6 mm. A polishing pad was prepared in the same manner as in Example 1.

  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.

  As is clear from the results in Table 1 above, the polishing pads of the present invention of Examples 1 and 2 have a higher polishing rate and better in-plane uniformity than the polishing pad of Comparative Example 1. It can be seen that the uniformity of the wafer surface is high.

It is the schematic plan view (A) and schematic sectional drawing (B and C) of one embodiment of the polishing pad of this invention. It is the schematic plan view (A) and A-A 'schematic sectional drawing (B) of another embodiment of the polishing pad of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Polishing pad 2 ... Groove a ... Center part in polishing surface of polishing pad b ... Center part in polishing surface of polishing pad c ... Peripheral part in polishing surface of polishing pad

Claims (8)

  A polishing pad having a plurality of parallel groove groups consisting of substantially straight grooves parallel to each other in the polishing surface, wherein at least one of the grooves is a different depth groove having a different groove depth in the same groove. A polishing pad having a plurality of parallel groove groups.   The polishing pad according to claim 1, wherein the plurality of parallel groove groups are parallel groove groups orthogonal to each other.   The polishing pad according to claim 1 or 2, wherein a groove depth in the different depth groove is formed large at a center portion and an intermediate portion of the polishing pad and small at an outer peripheral portion.   The polishing pad according to claim 1, wherein the groove depth in the different depth groove is small at the center portion of the polishing pad, large at the intermediate portion, and small at the outer peripheral portion.   5. The polishing pad according to claim 1, wherein DH / DA is 2 or more when the maximum depth of the groove depth in the different depth groove is DH and the minimum depth of the groove depth is DA.   A polishing method comprising polishing an object to be polished using the polishing pad according to claim 1.   A method for manufacturing a semiconductor device, wherein the method is manufactured using the polishing method according to claim 6. A semiconductor device manufactured by the manufacturing method according to claim 7.

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