JP2013052491A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad with excellent polishing speed stability, and to provide a method for manufacturing the polishing pad.SOLUTION: The polishing pad includes a polishing layer composed of a polyurethane resin foam containing miniature pores. The polyurethane resin foam contains a polysiloxane group-containing diol represented by general formula (1) as one of its raw materials, and the content of the polysiloxane group-containing diol is 1-10 wt.% in relation to the total raw materials of the polyurethane resin foam. In the formula, Ris a 1-12C alkyl group, n is an integer of 10-380, and m is an integer of 1-12.

Description

  The present invention stabilizes flattening processing of optical materials such as lenses and reflecting mirrors, silicon wafers, glass substrates for hard disks, aluminum substrates, and materials that require high surface flatness such as general metal polishing processing, In addition, the present invention relates to a polishing pad that can be performed with high polishing efficiency. The polishing pad of the present invention is suitably used in a step of flattening a semiconductor device having a Cu film (including a Cu alloy film) formed on a wafer to form a Cu wiring pattern.

  A typical material that requires high surface flatness is a single crystal silicon disk called a silicon wafer for manufacturing a semiconductor integrated circuit (IC, LSI). Silicon wafers have a highly accurate surface in each process of stacking and forming oxide layers and metal layers in order to form reliable semiconductor junctions of various thin films used for circuit formation in IC, LSI, and other manufacturing processes. It is required to finish flat. In such a polishing finishing process, a polishing pad is generally fixed to a rotatable support disk called a platen, and a workpiece such as a semiconductor wafer is fixed to a polishing head. A polishing operation is performed by generating a relative speed between the platen and the polishing head by both movements, and continuously supplying a polishing slurry containing abrasive grains onto the polishing pad.

  As the polishing characteristics of the polishing pad, it is required that the polishing object has excellent flatness (planarity) and in-plane uniformity and has a high polishing rate. The flatness and in-plane uniformity of the object to be polished can be improved to some extent by increasing the elastic modulus of the polishing layer. The polishing rate can be improved by using a foam containing bubbles and increasing the amount of slurry retained.

  Examples of a method for increasing the amount of slurry retained include a method for making the polishing pad itself hydrophilic. Specifically, (1) a method for introducing a hydrophilic group such as a hydroxyl group into a matrix material, (2 ) A method of mixing a matrix material and a hydrophilic substance is mentioned. For example, a polishing pad composition containing (A) a crosslinked elastomer and (B) a substance having a functional group such as a hydroxyl group is disclosed (Patent Document 1). Further, a polishing tool is disclosed in which a hydrophilic substance is further added to a material constituting the polishing tool or a hydrophilic group is added (modified) (Patent Document 2). Further, a polishing pad made of a thermosetting polymer matrix resin containing a sheet that is hydrophilic and substantially insoluble in water is disclosed (Patent Document 3). Furthermore, a polishing pad made of a polyurethane composition containing a urethane resin copolymerized with a compound having a hydrophilic group and containing a hydrophilic agent is disclosed (Patent Document 4).

  However, when the polishing pad itself is made hydrophilic, there is a problem in that the discharge performance of the slurry containing polishing waste is deteriorated and the polishing rate is gradually reduced.

  On the other hand, in order to impart excellent demoldability, surface smoothness, and adhesion in coating to a thermosetting urethane resin, a technique using a one-end diol polysiloxane as a raw material for an NCO-terminated prepolymer has been proposed ( Patent Document 5).

JP 2002-134445 A JP 2003-11066 A JP 2002-59358 A JP 2003-128910 A JP-A-7-133337

  An object of this invention is to provide the polishing pad excellent in polishing-rate stability, and its manufacturing method.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following polishing pad, and have completed the present invention.

The present invention provides a polishing pad having a polishing layer made of a polyurethane resin foam containing hollow fine bodies, wherein the polyurethane resin foam contains a polysiloxane group-containing diol represented by the following general formula (1) as a raw material,
The content of the polysiloxane group-containing diol relates to a polishing pad, which is 1 to 10% by weight with respect to all raw materials of the polyurethane resin foam.

(In the formula, R ₁ is an alkyl group having 1 to 12 carbon atoms, n is an integer of 10 to 380, and m is an integer of 1 to 12).

  By adding the polysiloxane group-containing diol represented by the general formula (1) as a raw material of the polyurethane resin foam, the polyurethane resin foam can be hydrophobized. As a result, since the slurry discharging property of the polishing layer is improved, the water absorption and swelling properties of the polishing layer are reduced, so that a reduction in polishing rate can be suppressed even when a polishing operation is performed for a long time. .

  In addition, in the polishing of a Cu film having a strong chemical polishing action, when the polishing layer is hydrophilic, the slurry after the chemical reaction tends to remain on the polishing layer. The speed tends to decrease gradually. By using a polishing layer made of a polyurethane resin foam that has been hydrophobized, it is possible to quickly discharge a chemically-reacted slurry without leaving it on the polishing layer, and to supply a new slurry quickly. And the polishing rate can be kept high.

  Content of polysiloxane group containing diol is 1 to 10 weight% with respect to all the raw materials of a polyurethane resin foam. When the content of the polysiloxane group-containing diol is less than 1% by weight, the polyurethane resin foam cannot be sufficiently hydrophobized, so that it is difficult to suppress a decrease in the polishing rate. On the other hand, when it exceeds 10% by weight, the compatibility with other raw materials is deteriorated and mechanical properties are lowered, or the hydrophobicity of the polyurethane resin foam becomes too strong, and the polishing rate is lowered.

  The hydroxyl value of the polysiloxane group-containing diol is preferably 7 to 120 mgKOH / g. When the hydroxyl value is less than 7 mgKOH / g, the polyurethane resin foam has insufficient hydrophobicity, and the intended effect tends to be difficult to obtain. On the other hand, when it exceeds 120 mgKOH / g, the compatibility with other raw materials is deteriorated and mechanical properties are lowered, or the hydrophobicity of the polyurethane resin foam is too strong and the polishing rate tends to be lowered. .

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

  The polishing pad of the present invention is more hydrophobic than the conventional polishing pad, and improves the slurry drainability of the polishing layer and decreases the water absorption and swelling of the polishing layer. Even if it is a case, the fall of a grinding | polishing rate can be suppressed. In addition, when the polishing pad of the present invention is used for Cu film polishing, it is possible to quickly discharge a chemically-reacted slurry without remaining on the polishing layer, and to supply a new slurry quickly. And the polishing rate can be kept high.

Schematic configuration diagram showing an example of a polishing apparatus used in CMP polishing

  The polishing pad of the present invention may be only a polishing layer made of a polyurethane resin foam, or may be a laminate of a polishing layer and another layer (such as a cushion layer).

The polyurethane resin foam contains at least an isocyanate component, a high molecular weight polyol, a polysiloxane group-containing diol represented by the following general formula (1), and a hollow microbody as raw material components.

(In the formula, R ₁ is an alkyl group having 1 to 12 carbon atoms, n is an integer of 10 to 380, and m is an integer of 1 to 12).

  As the isocyanate component, a known compound in the field of polyurethane can be used without particular limitation. As the isocyanate component, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, Aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate; ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, etc. Aliphatic diisocyanate; 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate Isocyanate, cycloaliphatic diisocyanates such as norbornane diisocyanate. These may be used alone or in combination of two or more.

  As the isocyanate component, a trifunctional or higher polyfunctional polyisocyanate compound can be used in addition to the diisocyanate compound. As a polyfunctional isocyanate compound, a series of diisocyanate adduct compounds are commercially available as Desmodur-N (manufactured by Bayer) or trade name Duranate (manufactured by Asahi Kasei Kogyo Co., Ltd.).

  Examples of the high molecular weight polyol include those usually used in the technical field of polyurethane. Examples include polyether polyols typified by polytetramethylene ether glycol, polyethylene glycol, etc., polyester polyols typified by polybutylene adipate, polycaprolactone polyols, reactants of polyester glycols such as polycaprolactone and alkylene carbonate, etc. Polyester polycarbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol and then reacting the obtained reaction mixture with organic dicarboxylic acid, polycarbonate polyol obtained by transesterification of polyhydroxyl compound and aryl carbonate Etc. These may be used alone or in combination of two or more. Among these, it is preferable to use polytetramethylene ether glycol from the viewpoint of enhancing the mechanical properties of the polishing layer and the hydrophobicity of the polishing layer.

  Although the weight average molecular weight of high molecular weight polyol is not specifically limited, From viewpoints, such as the elastic characteristic of the polyurethane resin obtained, it is preferable that it is 500-1500. When the weight average molecular weight is less than 500, the polyurethane resin obtained by using the polyurethane resin does not have sufficient elastic properties and tends to be a brittle polymer, the polishing pad made of this polyurethane resin becomes too hard, and the surface of the object to be polished is May cause scratches. Moreover, since it becomes easy to wear, it is not preferable from the viewpoint of the life of the polishing pad. On the other hand, when the weight average molecular weight exceeds 1500, a polishing pad made of a polyurethane resin obtained by using this becomes soft, and it becomes difficult to obtain a sufficiently satisfactory planarity.

  In addition to the high molecular weight polyols described above, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2 , 3-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2- Hydroxyethoxy) benzene, trimethylolpropane, glycerin, 1,2,6-hexanetriol, pentaerythritol, tetramethylolcyclohexane, methylglucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (hydroxy) Chill) cyclohexanol, diethanolamine, N- methyldiethanolamine, and can be used in combination of low molecular weight polyols such as triethanolamine. Moreover, low molecular weight polyamines, such as ethylenediamine, tolylenediamine, diphenylmethanediamine, and diethylenetriamine, can also be used in combination. Also, alcohol amines such as monoethanolamine, 2- (2-aminoethylamino) ethanol, and monopropanolamine can be used in combination. These low molecular weight polyols and low molecular weight polyamines may be used alone or in combination of two or more. The blending amount of these low molecular weight polyols, low molecular weight polyamines and the like is not particularly limited and is appropriately determined depending on the properties required for the polishing pad, but is preferably 20 to 70 mol% of the total polyol components.

The polysiloxane group-containing diol represented by the general formula (1) is used to introduce a polysiloxane group into the side chain of polyurethane by reacting with an isocyanate component, and to impart hydrophobicity to the polyurethane resin. It is a raw material. In the general formula (1), R ₁ is preferably a butyl group, and m is preferably 3.

  The polysiloxane group-containing diol preferably has a hydroxyl value of 7 to 120 mgKOH / g, more preferably 20 to 120 mgKOH / g.

The polysiloxane group-containing diol can be synthesized, for example, by dehydrating and condensing a polysiloxane having a hydroxyl group and trimethylolpropane. Commercial examples of the polysiloxane group-containing diol, for example, FM-DA11 (Chisso Corporation, _{R 1:} butyl group, m: 3, weight average molecular weight: 1000, hydroxyl value: 112.2mgKOH / g), FM-DA21 (Chisso Corporation, R ₁ : butyl group, m: 3, weight average molecular weight: 5000, hydroxyl value: 22.4 mgKOH / g), FM-DA26 (Chisso Corporation, R ₁ : butyl group, m: 3, weight average molecular weight: 15000, hydroxyl value: 7.5 mg KOH / g) and the like.

  The polysiloxane group-containing diol is used in an amount of 1 to 10% by weight based on the total raw material of the polyurethane resin foam.

  When a polyurethane resin foam is produced by a prepolymer method, a chain extender is used for curing the prepolymer. The chain extender is an organic compound having at least two active hydrogen groups, and examples of the active hydrogen group include a hydroxyl group, a primary or secondary amino group, and a thiol group (SH). Specifically, 4,4′-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline), 3,5 -Bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2 , 6-diamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 4,4′-diamino-3,3 ′, 5,5′-tetraethyldiphenylmethane, 4, 4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetra Sopropyldiphenylmethane, 1,2-bis (2-aminophenylthio) ethane, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane, N, N′-di-sec-butyl -4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, m-xylylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, m-phenylenediamine And polyamines exemplified by p-xylylenediamine and the like, or the low molecular weight polyols and low molecular weight polyamines mentioned above. These may be used alone or in combination of two or more.

  The polysiloxane group-containing diol may be used as a chain extender.

  The ratio of the isocyanate component, the polyol component, and the chain extender in the present invention can be variously changed depending on the molecular weight of each, the desired physical properties of the polishing pad, and the like. In order to obtain a polishing pad having desired polishing characteristics, the number of isocyanate groups of the isocyanate component relative to the total number of active hydrogen groups (hydroxyl group + amino group) of the polyol component and the chain extender is 0.80 to 1.20. Is more preferable, and 0.99 to 1.15 is more preferable. When the number of isocyanate groups is outside the above range, curing failure occurs and the required specific gravity and hardness cannot be obtained, and the polishing characteristics tend to be deteriorated.

  The polyurethane resin foam can be produced by applying a known urethanization technique such as a melting method or a solution method, but is preferably produced by a melting method in consideration of cost, work environment, and the like.

  The polyurethane resin foam can be produced by either the prepolymer method or the one-shot method. However, an isocyanate-terminated prepolymer is synthesized beforehand from an isocyanate component and a polyol component, and this is reacted with a chain extender. The polymer method is preferred because the resulting polyurethane resin has excellent physical properties.

  In the present invention, in order to make the polyurethane resin into a foam, a hollow micro object is used. In the prepolymer method, the hollow microparticles may be added to the first component containing the isocyanate-terminated prepolymer, or may be added to the second component containing the chain extender, but uniformly in the polyurethane resin foam. It is preferable to add to the first component for dispersion.

  The hollow microscopic body has a hollow inside and an outer wall made of resin. In the present invention, known hollow micro-objects can be used without particular limitation. For example, EXPANSEL DE (manufactured by Nippon Philite), Micropearl (manufactured by Matsumoto Yushi Kogyo), ARBOCEL (manufactured by Rettenmeier & Sone), Matsumoto Micro Examples include Sphere F (manufactured by Matsumoto Yushi Seiyaku).

  The addition amount of the hollow fine body is not particularly limited, but is preferably added to the polyurethane resin foam so as to be 0.1 to 10% by weight, and more preferably 0.3 to 5% by weight.

  In addition, you may add stabilizers, such as antioxidant, a lubricant, a pigment, a filler, an antistatic agent, and another additive as needed.

Specific examples in the case where the thermosetting polyurethane resin foam constituting the polishing pad (polishing layer) is produced by the prepolymer method will be described below. The manufacturing method of this polyurethane resin foam has the following processes.
1) Mixing step of hollow fine bodies The hollow fine bodies are added to the first component containing the isocyanate-terminated prepolymer and dispersed uniformly to obtain a dispersion. When the prepolymer is solid at normal temperature, it is preheated to an appropriate temperature and melted before use.
2) Mixing step of curing agent (chain extender) A second component containing a chain extender is added to and mixed with the dispersion to obtain a reaction solution.
3) Casting step The reaction solution is poured into a mold.
4) Curing step The reaction solution poured into the mold is heated to cause reaction curing.

  In the production method of polyurethane resin foam, heating and post-curing the foam that has reacted until the reaction liquid is poured into the mold and no longer flows is effective in improving the physical properties of the foam and is extremely suitable. It is.

  You may use the catalyst which accelerates | stimulates well-known polyurethane reactions, such as a tertiary amine type | system | group. The type and addition amount of the catalyst are selected in consideration of the flow time for pouring into a mold having a predetermined shape after the mixing step.

  Polyurethane resin foam can be manufactured by batch feeding each component into a container and stirring, or by continuously supplying each component to the stirrer and stirring, sending out the reaction liquid and molding It may be a continuous production method for manufacturing products.

  Also, put the prepolymer and hollow micro-particles, which are the raw materials for polyurethane resin foam, into the reaction vessel, then add the chain extender, stir, and then cast into a casting mold of a predetermined size. A thin sheet may be formed in a method of slicing using a hook-shaped or band saw-shaped slicer, or in the above-described casting step. Alternatively, a raw material resin may be dissolved and extruded from a T-die to directly obtain a sheet-like polyurethane resin foam.

  Moreover, as a manufacturing method of a polyurethane resin foam, you may use together well-known methods, such as a mechanical foaming method and a chemical foaming method.

  The average cell diameter of the hollow fine bodies in the polyurethane resin foam is preferably 150 μm or less, more preferably 30 to 70 μm. When deviating from this range, the planarity (flatness) of the polished object after polishing tends to decrease.

  The polyurethane resin foam preferably has a hardness of 40 to 70 degrees as measured by an Asker D hardness meter. When the Asker D hardness is less than 40 degrees, the planarity of the object to be polished is lowered. On the other hand, when it exceeds 70 degrees, the planarity is good, but the uniformity (uniformity) of the object to be polished is lowered. There is a tendency.

  The specific gravity of the polyurethane resin foam is preferably 0.5 to 1.3. When the specific gravity is less than 0.5, the surface strength of the polishing layer decreases, and the planarity of the object to be polished tends to decrease. On the other hand, when the ratio is larger than 1.3, the number of bubbles on the surface of the polishing layer is reduced and planarity is good, but the polishing rate tends to decrease.

  The polyurethane resin foam preferably has a water absorption of 3.7% or less, more preferably 3.5% or less. The polyurethane resin foam preferably has a bending elastic change rate (wet / dry) of 40% or less, more preferably 35% or less. In addition, the measuring method of each said physical property is based on description of an Example.

  The polishing surface of the polishing pad (polishing layer) of the present invention that is in contact with the object to be polished preferably has a surface shape that holds and renews the slurry. The polishing layer made of foam has many openings on the polishing surface and has the function of holding and renewing the slurry. However, in order to more efficiently retain the slurry and renew the slurry, it is also a subject of polishing. In order to prevent destruction of the object to be polished due to adsorption with the object, it is preferable that the polishing surface has an uneven structure. The concavo-convex structure is not particularly limited as long as it is a shape that holds and renews the slurry. For example, an XY lattice groove, a concentric circular groove, a through hole, a hole that does not penetrate, a polygonal column, a cylinder, a spiral groove, Examples include eccentric circular grooves, radial grooves, and combinations of these grooves. In addition, these uneven structures are generally regular, but in order to make the slurry retention and renewability desirable, the groove pitch, groove width, groove depth, etc. should be changed for each range. Is also possible.

  The method for producing the concavo-convex structure is not particularly limited. For example, a method of machine cutting using a jig such as a tool of a predetermined size, pouring a resin into a mold having a predetermined surface shape, and curing. Using a press plate having a predetermined surface shape, a method of producing a resin by pressing, a method of producing using photolithography, a method of producing using a printing technique, a carbon dioxide laser, etc. Examples include a manufacturing method using laser light.

  The polishing pad of the present invention may be a laminate of the polishing layer and a cushion sheet.

  The cushion sheet (cushion layer) supplements the characteristics of the polishing layer. The cushion sheet is necessary for achieving both planarity and uniformity in a trade-off relationship in CMP. Planarity refers to the flatness of a pattern portion when a polishing object having minute irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire polishing object. The planarity is improved by the characteristics of the polishing layer, and the uniformity is improved by the characteristics of the cushion sheet. In the polishing pad of the present invention, it is preferable to use a cushion sheet that is softer than the polishing layer.

  Examples of the cushion sheet include a fiber nonwoven fabric such as a polyester nonwoven fabric, a nylon nonwoven fabric, and an acrylic nonwoven fabric, a resin-impregnated nonwoven fabric such as a polyester nonwoven fabric impregnated with polyurethane, a polymer resin foam such as polyurethane foam and polyethylene foam, a butadiene rubber, Examples thereof include rubber resins such as isoprene rubber and photosensitive resins.

  Examples of means for attaching the polishing layer and the cushion sheet include a method of pressing the polishing layer and the cushion sheet with a double-sided tape.

  The double-sided tape has a general configuration in which adhesive layers are provided on both sides of a substrate such as a nonwoven fabric or a film. In consideration of preventing the penetration of the slurry into the cushion sheet, it is preferable to use a film for the substrate. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. Considering the content of metal ions, an acrylic adhesive is preferable because the metal ion content is low. In addition, since the composition of the polishing layer and the cushion sheet may be different, the composition of each adhesive layer of the double-sided tape can be made different so that the adhesive force of each layer can be optimized.

  The polishing pad of the present invention may be provided with a double-sided tape on the surface to be bonded to the platen. As the double-sided tape, a tape having a general configuration in which an adhesive layer is provided on both surfaces of a base material can be used as described above. As a base material, a nonwoven fabric, a film, etc. are mentioned, for example. In consideration of peeling from the platen after use of the polishing pad, it is preferable to use a film for the substrate. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. Considering the content of metal ions, an acrylic adhesive is preferable because the metal ion content is low.

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

  As a result, the protruding portion of the surface of the semiconductor wafer 4 is removed and polished flat. Thereafter, a semiconductor device is manufactured by dicing, bonding, packaging, or the like. The semiconductor device is used for an arithmetic processing device, a memory, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Measurement and evaluation methods]
(Measurement of weight average molecular weight of polyol component)
The weight average molecular weight of the polyol component was measured by GPC (gel permeation chromatography) and converted by standard polystyrene.
GPC device: manufactured by Shimadzu Corporation, LC-10A
Column: Polymer Laboratories, (PLgel, 5 μm, 500 mm), (PLgel, 5 μm, 100 mm), and (PLgel, 5 μm, 50 mm) connected to three columns, flow rate: 1.0 ml / min
Concentration: 1.0 g / l
Injection volume: 40 μl
Column temperature: 40 ° C
Eluent: Tetrahydrofuran

(Measurement of hardness)
This was performed in accordance with JIS K6253-1997. The produced polyurethane resin foam was cut into a size of 2 cm × 2 cm (thickness: arbitrary) and used as a sample for hardness measurement, and was 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 (manufactured by Kobunshi Keiki Co., Ltd., Asker D type hardness meter).

(Measurement of specific gravity)
This was performed according to JIS Z8807-1976. The produced polyurethane resin foam was cut into a 4 cm × 8.5 cm strip (thickness: arbitrary) and 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%. I put it. The specific gravity was measured using a hydrometer (manufactured by Sartorius).

(Measurement of water absorption)
The measurement was performed according to JIS K7312. A sample obtained by cutting out the produced polyurethane resin foam into a size of width 20 mm × length 50 mm × thickness 1.27 mm was used as a sample. The sample was immersed in distilled water at 25 ° C. for 48 hours, and the water absorption was calculated by substituting the weight before and after immersion into the following formula.
Water absorption rate (%) = [(weight after immersion−weight before immersion) / weight before immersion] × 100

(Measurement of bending elastic change rate)
A sample obtained by cutting the produced polyurethane resin foam into a size of 1 cm in width, 3 cm in length, and 2 mm in thickness was used as a sample. Using a 5864 tabletop test system manufactured by Instron as a measuring device, the stress and strain of the sample under the conditions of the distance between the intersections of the bending strength measuring jig 22 mm, the crosshead speed 0.6 mm / min, and the displacement 6.0 mm. Was measured, and the flexural modulus was calculated by the following formula.
Flexural modulus = (Stress difference between two points on a straight line) / (Strain difference between the same two points)
Further, the sample was immersed in distilled water at 23 ° C. ± 2 ° C. for 48 hours, and then the flexural modulus was calculated by the same method as described above.
The bending elastic change rate was calculated by the following formula.
Bending elastic change rate (%) = (bending elastic modulus before dipping−bending elastic modulus after dipping) / (bending elastic modulus before dipping) × 100

(Measurement of polishing rate)
Using SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) as the polishing apparatus, the polishing rate was measured using the prepared polishing pad. The polishing rate was as follows: a thermal oxide film of 2000 mm, Ta100 mm, TaN100 mm, and Cu-seed 800 mm were deposited in this order on an 8-inch silicon wafer, and a Cu plating of 25000 mm was formed on this and polished for 60 seconds. It was calculated from the polishing amount at this time. The initial polishing rate was the fourth polishing rate. The late polishing rate was the 12th polishing rate. And the polishing rate maintenance rate was computed by the following formula.
Polishing rate maintenance rate (%) = [1-{(initial polishing rate−late polishing rate) / initial polishing rate}] × 100
A non-contact resistance measuring system (manufactured by Napson, Model-NC-80M) was used for the film thickness measurement of the Cu film. As polishing conditions, a slurry prepared by adding 1 wt% of hydrogen peroxide to a neutral slurry for Cu (manufactured by Fujimi Incorporated, PL7101) was added at a flow rate of 200 ml / min. The polishing load was 2 psi, the polishing platen rotation speed was 70 rpm, and the wafer rotation speed was 70 rpm. After the prepared polishing pad was attached to the platen, the surface of the polishing pad was dressed for 30 minutes using a diamond abrasive disc (M # 100, manufactured by Asahi Diamond Co., Ltd.). The dressing conditions were a disk load of 0.6 psi, a polishing surface plate rotation speed of 30 rpm, and a disk rotation speed of 15 rpm.

Example 1
In a container, 1173 parts by weight of toluene diisocyanate (mixture of 2,4-form / 2,6-form = 80/20), 264 parts by weight of isophorone diisocyanate, polysiloxane group-containing diol A represented by the general formula (1) Ltd., FM-DA11, R ₁ : butyl group, m: 3, weight average molecular weight: 1000, hydroxyl value: 112.2 mgKOH / g) 48 parts by weight, polytetramethylene ether glycol 1638 parts by weight of weight average molecular weight 1000, 283 parts by weight of polytetramethylene ether glycol having a weight average molecular weight of 650 and 195 parts by weight of diethylene glycol were added and reacted at 70 ° C. for 4 hours to obtain an isocyanate-terminated prepolymer A (NCO wt%: 9.25 wt%).
100 parts by weight of the above-mentioned prepolymer A adjusted to 70 ° C. and degassed under reduced pressure, and 3 parts by weight of EXPANSEL 551DE (manufactured by Nippon Philite) as a hollow fine body are added to the polymerization vessel, and 3 minutes by a hybrid mixer (manufactured by Keyence). Mixed. The obtained mixture was degassed under reduced pressure at 70 ° C. for 1 hour to obtain a dispersion. 26.4 parts by weight of 4,4′-methylenebis (o-chloroaniline) previously melted at 120 ° C. was added thereto (NCO Index: 1.1), and mixed for 1 minute with a hybrid mixer to prepare a reaction solution. . Then, the reaction solution was poured into a pan-type open mold (casting container). When the fluidity of the reaction solution disappeared, it was placed in an oven and post-cured at 100 ° C. for 16 hours to obtain a polyurethane resin foam block.
The polyurethane resin foam block heated to about 80 ° C. was sliced using a slicer (manufactured by Amitech, VGW-125) to obtain a polyurethane resin foam sheet. Next, using a buffing machine (Amitech Co., Ltd.), the surface of the sheet was buffed to a thickness of 1.27 mm to obtain a sheet with an adjusted thickness accuracy. The buffed sheet is punched out with a diameter of 61 cm, and a concentric circle having a groove width of 0.25 mm, a groove pitch of 1.50 mm, and a groove depth of 0.40 mm on the surface using a groove processing machine (manufactured by Techno). Groove processing was performed to obtain a polishing layer. A double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape) was attached to the surface of the polishing layer opposite to the grooved surface using a laminator. Furthermore, the surface of the cushion sheet (Toray Industries, Inc., polyethylene foam, Torepef, thickness 0.8 mm) subjected to corona treatment was buffed and bonded to the double-sided tape using a laminator. Further, a double-sided tape was attached to the other surface of the cushion sheet using a laminator to prepare a polishing pad.

Examples 2-7, Comparative Examples 1-4
A polishing pad was prepared in the same manner as in Example 1 except that the formulation shown in Table 1 was adopted. The polysiloxane group-containing diols B and C in Table 1 are as follows.
Polysiloxane group-containing diol B represented by the general formula (1) (Chisso Corporation, FM-DA21, R ₁ : butyl group, m: 3, weight average molecular weight: 5000, hydroxyl value: 22.4 mgKOH / g)
Polysiloxane group-containing diol C represented by the general formula (1) (Chisso Corporation, FM-DA26, R ₁ : butyl group, m: 3, weight average molecular weight: 15000, hydroxyl value: 7.5 mgKOH / g)

  The polishing pad of the present invention is used to flatten optical materials such as lenses and reflection mirrors, silicon wafers, glass substrates for hard disks, aluminum substrates, and materials that require high surface flatness such as general metal polishing. Used for processing. In particular, the polishing pad of the present invention is suitably used in a step of planarizing a semiconductor device having a Cu film (including a Cu alloy film) formed on a wafer to form a Cu wiring pattern.

1: Polishing pad (polishing layer)
2: Polishing surface plate 3: Abrasive (slurry)
4: Polishing object (semiconductor wafer)
5: Support base (polishing head)
6, 7: Rotating shaft

Claims (3)

In a polishing pad having a polishing layer made of a polyurethane resin foam containing hollow fine bodies, the polyurethane resin foam contains a polysiloxane group-containing diol represented by the following general formula (1) as a raw material,
The polishing pad according to claim 1, wherein the content of the polysiloxane group-containing diol is 1 to 10% by weight with respect to the total raw material of the polyurethane resin foam.

(In the formula, R ₁ is an alkyl group having 1 to 12 carbon atoms, n is an integer of 10 to 380, and m is an integer of 1 to 12). The polishing pad according to claim 1, wherein the polysiloxane group-containing diol has a hydroxyl value of 7 to 120 mgKOH / g. A method for manufacturing a semiconductor device, comprising a step of polishing a surface of a semiconductor wafer using the polishing pad according to claim 1.