JPWO2012077592A1 - Chemical mechanical polishing pad and chemical mechanical polishing method using the same - Google Patents

Abstract

The chemical mechanical polishing pad according to the present invention has a polishing layer formed from a composition containing polyurethane, the specific gravity of the polishing layer is 1.1 or more and 1.3 or less, and the heat of the polishing layer is The conductivity is 0.2 [W / m · K] or more.

Description

  The present invention relates to a chemical mechanical polishing pad and a chemical mechanical polishing method using the chemical mechanical polishing pad.

  Conventionally, as a polishing pad for polishing glass or a semiconductor element, a porous nonwoven fabric or a polyurethane molded product obtained by impregnating a nonwoven fabric with a polyurethane solution has been used. In particular, as a chemical mechanical polishing pad suitable for chemical mechanical polishing (hereinafter also referred to as “CMP”) for flattening the surface of a semiconductor substrate, a polishing pad made of polyurethane as exemplified below has been studied. .

  For example, in Japanese translations of PCT publication No. 8-500622, a polishing pad in which a filler-like component is dispersed in polyurethane, and in Japanese Unexamined Patent Publication No. 2000-17252 and Japanese Patent No. 3956364, a polishing pad using foamed polyurethane is studied. Yes.

  When CMP is performed using such a polishing pad, frictional heat is generated due to friction between the surface to be polished such as the wafer surface and the surface of the polishing pad, and the temperature of the polishing pad surface may rise locally. there were. Such a local temperature increase on the surface of the polishing pad changes the polishing characteristics of the polishing pad, which may cause poor flatness of the surface to be polished and polishing defects (scratches). Further, if frictional heat accumulates in the polishing pad due to long-time CMP and the temperature continues to rise, the polishing characteristics of the entire polishing pad may change. In order to solve the problems caused by frictional heat of the polishing pad as described above, for example, in Japanese Patent Application Laid-Open Nos. 7-142432 and 2003-197586, circulation of cooling water is performed on a surface plate for fixing the polishing pad. A CMP apparatus incorporating this cooling mechanism has been developed.

  However, since the conventional chemical mechanical polishing pad has insufficient thermal conductivity, the approach from the CMP apparatus by improving the cooling mechanism has a limit. In particular, polyurethane foam, which is currently widely used as a raw material for polishing pads, has a low thermal conductivity due to its foam structure, and is also used as a heat insulating material for houses. In the polishing pad made of polyurethane foam having such properties, the above-mentioned (1) frictional heat causes a local temperature increase on the surface of the polishing pad to deteriorate the polishing characteristics, and (2) the frictional heat is dissipated. Since this is difficult, problems such as a change in polishing characteristics due to an increase in the temperature of the entire polishing pad due to long-time CMP have been significant.

  Therefore, some aspects of the present invention can solve the above-described problems, and can improve both the flatness of the surface to be polished in CMP and the reduction of polishing defects (scratches), and for a long time. The present invention provides a chemical mechanical polishing pad capable of maintaining stable polishing characteristics even over a wide range of CMP, and a chemical mechanical polishing method using the chemical mechanical polishing pad.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the chemical mechanical polishing pad according to the present invention is:
Having a polishing layer formed from a composition containing polyurethane;
A specific gravity of the polishing layer is 1.1 or more and 1.3 or less, and a thermal conductivity of the polishing layer is 0.2 [W / m · K] or more.

[Application Example 2]
In the chemical mechanical polishing pad of Application Example 1,
It has a laminate in which a support layer is formed on one surface side of the polishing layer,
The laminated body may have a thermal conductivity of 0.2 [W / m · K] or more.

[Application Example 3]
In the chemical mechanical polishing pad of Application Example 1 or Application Example 2,
Residual strain at the time of tension of the polishing layer may be 2% or more and 10% or less.

[Application Example 4]
In the chemical mechanical polishing pad of any one of Application Examples 1 to 3,
The volume change rate when the polishing layer is immersed in water at 23 ° C. for 24 hours may be 0.8% or more and 5.0% or less.

[Application Example 5]
In the chemical mechanical polishing pad of Application Example 2,
The support layer may have a compressibility of 5% or more.

[Application Example 6]
In the chemical mechanical polishing pad of any one of Application Examples 1 to 5,
The polyurethane may be a thermoplastic polyurethane.

[Application Example 7]
In the chemical mechanical polishing pad of any one of Application Examples 1 to 6,
The composition may further include water-soluble particles.

[Application Example 8]
One aspect of the chemical mechanical polishing method according to the present invention is:
Chemical mechanical polishing is performed using the chemical mechanical polishing pad of any one of Application Examples 1 to 7.

  The chemical mechanical polishing pad according to the present invention is provided with a polishing layer having a specific gravity and thermal conductivity within a specific range, thereby improving both the flatness of the surface to be polished and the reduction of polishing defects (scratches) in CMP. In addition, stable polishing characteristics can be maintained even in CMP over a long period of time.

FIG. 1 is a schematic diagram for explaining the concept of residual strain during tension of a polishing layer. 2A is an enlarged view of region I in FIG. FIG. 2B is an enlarged view of region I in FIG. FIG. 2C is an enlarged view of region I in FIG. 2D is an enlarged view of region I in FIG. FIG. 2E is an enlarged view of region I in FIG. FIG. 3A is a schematic diagram for explaining the concept of the volume change rate in the polishing layer. FIG. 3B is a schematic diagram for explaining the concept of the volume change rate in the polishing layer. FIG. 4A is a schematic diagram for explaining the concept of duro D hardness in the polishing layer. FIG. 4B is a schematic diagram for explaining the concept of duro D hardness in the polishing layer. FIG. 5A is a schematic diagram for explaining the concept of surface hardness in the polishing layer. FIG. 5B is a schematic diagram for explaining the concept of surface hardness in the polishing layer.

Hereinafter, preferred embodiments of the present invention will be described in detail. In the present invention, the “wet state” refers to a state when the polishing layer is immersed in water at 23 ° C. for 4 hours or more. Further, in this specification, the term “hardness” simply refers to Duro D hardness, and the term “surface hardness” refers to universal hardness [HU: N / mm ² ]. The surface hardness of the polishing layer in the wet state is represented by universal hardness [HU: N / mm ² ] when a constant pressure is applied, as will be described in the examples described later.

1. Chemical mechanical polishing pad The structure of the chemical mechanical polishing pad according to the present embodiment is not particularly limited as long as it has a polishing layer on at least one surface. The polishing layer has a specific gravity of 1.1 or more and 1.3 or less, and a thermal conductivity of 0.2 [W / m · K] or more. Hereinafter, the chemical mechanical polishing pad according to the present embodiment will be described in detail.

1.1. Polishing Layer The polishing layer constituting the chemical mechanical polishing pad according to the present embodiment is formed from a polyurethane-containing composition (hereinafter also simply referred to as “composition”) by a manufacturing method described later. As long as the polishing layer has a specific gravity and a thermal conductivity in the above ranges, the structure and type of polyurethane contained in the composition are not particularly limited. Therefore, an optimal polyurethane may be selected as appropriate in consideration of the material of the object to be polished and the affinity with the slurry used during polishing. In the present invention, the “polishing layer” refers to a single layer having a surface (hereinafter referred to as “polishing surface”) in contact with an object to be polished when chemical mechanical polishing is performed. That is, in the present invention, another layer that does not have a polishing surface may be included between the polishing layer and the support layer, but the other layer does not have a polishing surface and thus is not a “polishing layer”.

  Generally, the polishing layer containing polyurethane is classified into a foam type and a non-foam type. In the case of a non-foaming type polishing layer that is currently widely used, the specific gravity and hardness of the non-foaming type polishing layer are larger than the foaming type due to its structure. Elastic deformation is reduced. As a result, the flatness of the surface to be polished tends to be good. On the other hand, since the hardness of the polishing layer is larger than that of the foam type, there is a tendency that the generation of polishing defects (scratches, etc.) increases due to polishing scraps and pad scraps entering between the surface to be polished and the polishing layer.

  On the other hand, in the case of a foam type polishing layer, the specific gravity and hardness tend to decrease due to the structure. As a result, polishing debris and pad debris that have entered between the surface to be polished (the surface of the wafer, etc.) and the polishing layer are captured by the surface of the flexible polishing layer, and the polishing debris and pad are pressed against the surface to be polished with a strong pressure. Since it is possible to avoid scraps coming into contact with each other, generation of polishing defects can be reduced. On the other hand, since the elastic deformation of the polishing layer increases following the unevenness of the surface to be polished, the flatness of the surface to be polished tends to deteriorate. From the above, it has been considered that improvement in flatness of a surface to be polished (surface of a wafer or the like) and reduction of polishing defects (scratch or the like) are contradictory characteristics.

  However, the present inventors prepared a polishing layer using a composition containing polyurethane, and controlled the specific gravity and thermal conductivity of the polishing layer, so that the surface to be polished, which had been difficult in the prior art, was obtained. It has been found that it is possible to achieve both improvement in flatness (surface of a wafer or the like) and reduction of polishing defects (such as scratches), and stable polishing characteristics can be obtained even in CMP over a long period of time.

1.1.1. Composition 1.1.1.1. Polyurethane As described above, the structure and type of polyurethane contained in the composition are not particularly limited. However, when the object to be polished is a semiconductor wafer having wiring, improvement in flatness of the surface to be polished and polishing defects ( From the viewpoint of achieving both reduction in scratches), it is preferable to use thermoplastic polyurethane. More preferably, the thermoplastic polyurethane includes a repeating unit derived from at least one selected from alicyclic isocyanate and aromatic isocyanate. According to the composition containing the thermoplastic polyurethane having such a chemical structure, a polishing layer having excellent flexibility can be produced. By capturing polishing scraps and pad scraps that enter between the polished surface on the surface of the flexible polishing layer, it is possible to prevent them from contacting the polished surface with a strong pressing pressure. It is considered that the generation of polishing defects can be reduced. On the other hand, when a polishing layer containing polyurethane cross-linked using a heat-crosslinkable polyurethane (thermosetting polyurethane) is produced, it is difficult to impart sufficient flexibility to the polishing layer, resulting in a polishing defect. It is difficult to suppress the occurrence of.

  In addition, the polishing layer containing the polyurethane in which the heat-crosslinkable polyurethane is crosslinked and the molecular chain is firmly bonded is less likely to swell even when it comes into contact with water, compared to the polishing layer prepared using the thermoplastic polyurethane. It has properties, and the surface hardness in the wet state cannot be reduced. For this reason, when the polishing layer contains a crosslinked polyurethane, polishing scraps and pad scraps that have entered between the polished surface and the polishing surface will be captured on the surface of the polishing layer having a high surface hardness, Since they come into contact with the surface to be polished with a strong pressing pressure, generation of polishing defects cannot be suppressed.

  In addition, the polishing layer prepared from the composition containing a thermoplastic polyurethane containing a repeating unit derived from at least one selected from alicyclic isocyanate and aromatic isocyanate is easy to control the crystallinity, It becomes easy to control the specific gravity and hardness of the polishing layer.

  Examples of the alicyclic isocyanate include isophorone diisocyanate (IPDI), norbornene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate (hydrogenated MDI), and the like. These alicyclic isocyanates may be used alone or in combination of two or more.

  Examples of the aromatic isocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, and naphthalene. Aromatic diisocyanates such as diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylene diisocyanate and the like can be mentioned. Among these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 4,4'-diphenylmethane diisocyanate are preferable because the reaction control with a hydroxyl group is easy. These aromatic isocyanates may be used alone or in combination of two or more.

  In the thermoplastic polyurethane contained in the composition, an alicyclic isocyanate and an aromatic isocyanate may be used in combination, or other isocyanates may be used in combination. Examples of the other isocyanate include aliphatic diisocyanates such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 1,6-hexamethylene diisocyanate.

  In addition, it is more preferable that the thermoplastic polyurethane contained in the composition contains a repeating unit derived from alicyclic isocyanate. By including the repeating unit derived from the alicyclic isocyanate, the thermoplastic polyurethane exhibits appropriate hardness, and the surface hardness in the wet state can be more appropriately controlled, and the flexibility becomes larger. Therefore, it is suitable for the implementation of the present invention.

  Moreover, it is preferable that the thermoplastic polyurethane contained in the said composition further contains the repeating unit derived from at least 1 sort (s) selected from polyether polyol, polyester polyol, polycarbonate polyol, and polyolefin polyol. By including a repeating unit derived from the exemplified polyols, the water resistance of the thermoplastic polyurethane tends to be further improved.

  Moreover, the thermoplastic polyurethane contained in the composition may include a repeating unit derived from a chain extender. Examples of the chain extender include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Low molecular weight dihydric alcohols such as neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene It is done. Among these, ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, from the viewpoint of easy reaction control with an isocyanate group, 1,6-hexanediol is preferred, and 1,4-butanediol is more preferred.

  The thermoplastic polyurethane contained in the composition contains 2 to 60% by mass of a repeating unit derived from at least one selected from alicyclic isocyanate and aromatic isocyanate when the thermoplastic polyurethane is 100% by mass. It is preferable to contain 3-55 mass%, and it is more preferable to contain. By including a repeating unit derived from at least one selected from alicyclic isocyanate and aromatic isocyanate within the above range, the thermoplastic polyurethane exhibits appropriate hardness and appropriately controls the surface hardness in the wet state. It is possible to perform the present invention because it can be performed and flexibility is increased.

  The method for producing the thermoplastic polyurethane contained in the composition is not particularly limited, and can be produced according to a general method for producing polyurethane (for example, a conventionally known batch method or prepolymer method).

1.1.1.2. Water-absorbing polymer compound The composition may further contain a polymer compound other than thermoplastic polyurethane. The other polymer compound that can be added to the composition is preferably a polymer compound having a water absorption rate of 3 to 3000% (hereinafter also referred to as “water-absorbing polymer compound”). By adding the water-absorbing polymer compound, it is possible to impart appropriate water absorption to the polishing layer, and to easily control the volume change of the polishing layer that may occur due to swelling due to water absorption.

  Among the water-absorbing polymer compounds, a water-absorbing polymer compound containing at least one bond selected from an ether bond, an ester bond and an amide bond is more preferable.

  Examples of the water-absorbing polymer compound containing an ether bond include polyoxyethylene, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyether ester amide, polyether amide imide, polypropylene glycol, polyoxypropylene butyl ether, polyoxy Propylene glyceryl ether, polyoxypropylene sorbit, oxyethylene-epichlorohydrin copolymer, methoxypolyethylene glycol (meth) acrylate copolymer, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, poly Oxyethylene oleyl cetyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyethylene poly Xylpropylene butyl ether, polyoxyethylene polyoxypropylene hexylene glycol ether, polyoxyethylene polyoxypropylene trimethylolpropane, polyoxyethylene polyoxypropylene glyceryl ether, copolymer of monomer and ether containing an ether bond, chlorine-containing poly Examples include ether, polyacetal resin, alkyl glucoside, polyoxyethylene fatty acid amine and the like.

  Examples of the water-absorbing polymer compound containing an ester bond include polyoxyethylene fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, glycerin fatty acid ester, acrylic acid ester copolymer (acrylic rubber) Etc. Examples of the polyoxyethylene fatty acid ester include polyethylene glycol monostearate, polyethylene glycol laurate, polyethylene glycol monooleate, and polyethylene glycol distearate.

  Examples of the water-absorbing polymer compound containing an amide bond include fatty acid alkanolamides and modified polyamide resins.

  The molecular weight of the water-absorbing polymer compound is preferably from 500 to 1,000,000, more preferably from 5,000 to 500,000, as a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography.

The water absorption rate of the water-absorbing polymer compound in the present invention can be determined by the following method based on “JIS K6258”. First, a water-absorbing polymer compound is molded into a sheet having a thickness of 2 mm, and further cut into a size of 2 cm × 2 cm is immersed in water at 23 ° C. for 24 hours. The mass in the air before immersion (M1) and the mass in the air after immersion (M3) were measured, and the mass change rate was determined by the following formula (1), which was defined as the water absorption rate.
Water absorption (%) = ((M3−M1) / M1) × 100 (1)

  When the composition contains a water-absorbing polymer compound, the content thereof is preferably 1% by mass or more and 20% by mass or less when the total amount of the thermoplastic polyurethane and the water-absorbing polymer compound is 100% by mass. More preferably, it is 3 mass% or more and 15 mass% or less, Most preferably, it is 5 mass% or more and 10 mass% or less. When the content of the water-absorbing polymer compound is in the above range, the volume change rate in the wet state is easily adjusted to a range of 0.8% to 5.0%. When the volume change rate of the polishing layer is in the above range, the polishing layer surface is softened moderately by water absorption, so that the flatness of the surface to be polished is improved and polishing defects (scratches) can be reduced. .

1.1.1.3. Water-soluble particles The composition may further comprise water-soluble particles. Such water-soluble particles are preferably present in a state of being uniformly dispersed in the composition. By using such a composition, a polishing layer in which water-soluble particles are uniformly dispersed can be obtained.

  The water-soluble particles are held in contact with a polishing aqueous dispersion (hereinafter also referred to as “slurry”) composed of abrasive grains and a chemical solution, so that the water-soluble particles are released from the surface of the polishing layer to hold the slurry. It is used for the purpose of forming pores. For this reason, by using water-soluble particles without using a polyurethane foam having a cellular structure, pores are formed on the surface of the polishing layer, and the retention of the slurry becomes better. Moreover, since the pores are formed on the surface of the polishing layer, the surface hardness in the wet state can be controlled. Furthermore, it is possible to increase the specific gravity of the polishing layer by using particles having a large specific gravity.

  When the composition containing the thermoplastic polyurethane contains water-soluble particles, (1) since the water-soluble particles act as a reinforcing agent such as a filler, the elastic deformation of the polishing layer can be reduced. The flatness can be improved, (2) it is a non-foaming type polishing layer, so it has excellent mechanical strength, and (3) it is not necessary to use a precise technique to uniformly control the foamed cell structure. From the viewpoint of excellent productivity.

  The water-soluble particles are not particularly limited, and examples thereof include organic water-soluble particles and inorganic water-soluble particles. Specifically, in addition to a substance that dissolves in water such as a water-soluble polymer, a substance that can swell or gel by contact with water and be released from the surface of the polishing layer, such as a water-absorbent resin.

  Examples of the material constituting the organic water-soluble particles include saccharides (polysaccharides such as starch, dextrin and cyclodextrin, lactose, mannitol, etc.), celluloses (hydroxypropylcellulose, methylcellulose, etc.), proteins, polyvinyl alcohol, Examples include polyvinyl pyrrolidone, polyacrylic acid, polyethylene oxide, sulfonated polyisoprene, and sulfonated isoprene copolymers.

  Examples of the material constituting the inorganic water-soluble particles include potassium acetate, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium bromide, potassium phosphate, potassium sulfate, magnesium sulfate, and calcium nitrate.

  As the material constituting the water-soluble particles, the material constituting the organic water-soluble particles or the inorganic water-soluble particles may be used alone or in combination of two or more. The water-soluble particles are preferably solid from the viewpoint that the hardness and other mechanical strength of the polishing layer can be set to appropriate values.

  The content of water-soluble particles in the composition is preferably 3 to 150 parts by mass with respect to 100 parts by mass of the thermoplastic polyurethane. When the content of the water-soluble particles is in the above range, a polishing layer having a high polishing rate in chemical mechanical polishing and having an appropriate hardness and other mechanical strength can be produced.

  The average particle diameter of the water-soluble particles is preferably 0.5 to 200 μm. The size of the pores formed when the water-soluble particles are released from the polishing layer surface of the chemical mechanical polishing pad is preferably 0.1 to 500 μm, more preferably 0.5 to 200 μm. When the average particle diameter of the water-soluble particles is within the above range, a chemical mechanical polishing pad having a polishing layer exhibiting a high polishing rate and excellent mechanical strength can be produced.

1.1.2. Specific gravity The specific gravity of the polishing layer provided in the chemical mechanical polishing pad according to the present embodiment is 1.1 or more and 1.3 or less, and preferably 1.15 or more and 1.27 or less. When the specific gravity of the polishing layer is in the above range, the hardness of the polishing layer becomes appropriate, so that the flatness of the surface to be polished becomes good, and the elastic deformation (following property) of the polishing layer with respect to the unevenness of the surface to be polished is moderate Therefore, polishing defects (scratches) can be reduced. When the specific gravity of the polishing layer is less than the above range, it is not preferable because the hardness of the polishing layer becomes too low and the flatness of the surface to be polished is deteriorated. In addition, when the specific gravity of the polishing layer exceeds the above range, the hardness of the polishing layer becomes too high, and polishing defects (scratches) increase, which is not preferable.

  Note that the upper limit of the specific gravity of the polishing layer is 1.30 or less in consideration of the balance between the specific gravity of polyurethane currently known and the appropriate hardness of the polishing layer. In order to produce a polishing layer having a specific gravity exceeding 1.30, it is necessary to incorporate a material having a large specific gravity in addition to urethane into the polishing layer. For example, a polishing layer having a specific gravity exceeding 1.30 can be produced by mixing a material having a large specific gravity such as silica or alumina with urethane as a filler. However, in such a case, the hardness of the polishing layer is increased by the mixed filler, and scratches on the surface to be polished are greatly deteriorated, so that the function and effect of the polishing layer of the present invention cannot be achieved.

  In the present invention, the specific gravity of the polishing layer can be measured by a method based on “JIS Z8807”. Specifically, a sample with a known mass is placed in a Le Chatelier specific gravity bottle containing water, the volume of the sample is known from the rise of the liquid level due to the sample, and the specific gravity is obtained from the mass and volume of the sample.

  In addition, it is preferable that the polishing layer with which the chemical mechanical polishing pad which concerns on this Embodiment is provided is a non-foaming type from a viewpoint made into the specific gravity of the said range. In the present invention, the non-foaming type refers to a polishing layer that does not substantially contain bubbles. For reference, the specific gravity of a commercially available polishing pad such as “IC1000” manufactured by ROHM & HAAS is currently about 0.40 to 0.90.

1.1.3. Thermal conductivity The thermal conductivity of the polishing layer provided in the chemical mechanical polishing pad according to the present embodiment is 0.2 [W / m · K] or more and 0.3 [W / m · K] or more. It is preferable. If the thermal conductivity of the polishing layer is 0.2 [W / m · K] or more, the frictional heat generated when the surface to be polished and the surface of the polishing pad rub against each other can be quickly diffused into the polishing layer. It is possible to reduce a local temperature rise on the surface of the polishing pad. Further, the durability of the polishing layer can be improved by reducing the accumulation of frictional heat generated by long-time CMP in the polishing layer.

  In addition, according to the technical idea of the present application, the thermal conductivity of the polishing layer is preferably 0.2 [W / m · K] or more, but currently known general-purpose engineering plastics (general-purpose engineering plastics: polyvinyl alcohol) The upper limit of the thermal conductivity of polyvinyl chloride, epoxy resin, polyurethane, polyacrylic resin, polyester resin, etc.) is naturally 0.6 [W / m · K]. However, there is a polymer composition having a higher thermal conductivity by kneading a heat conductive filler or the like with the general-purpose engineering plastic. In addition, it is fully conceivable that new polyurethanes having higher thermal conductivity will be developed in the future. Therefore, the technical idea of the present invention is not limited by the upper limit value of the thermal conductivity described above.

In the present invention, the thermal conductivity of the polishing layer can be calculated from the thermal diffusion coefficient, specific heat, and specific gravity. Specifically, a test piece is placed on the sensor, and a 50 g weight is placed on top of a fixing jig provided with a micro heater. The thermal diffusion coefficient D is measured from the attenuation of the amplitude and the phase delay that occur when the temperature wave generated from the surface of the microheater diffuses in the thickness direction and reaches the back surface. From the obtained thermal diffusion coefficient D, specific heat ρ of the test piece, and specific gravity Cp, the thermal conductivity (W / m · K) is calculated by the following formula (2).
Thermal conductivity (W / m · K) = D / (ρ × Cp) (2)

  In addition, it is preferable that the polishing layer with which the chemical mechanical polishing pad which concerns on this Embodiment is provided is a non-foaming type from a viewpoint of setting it as the heat conductivity of the said range. Moreover, it is preferable to contain a filler with high heat conductivity, for example, the above-mentioned water-soluble particle | grains etc. can be contained as a filler. For reference, the thermal conductivity of a polishing layer of a general commercially available polishing pad such as “IC1000” manufactured by ROHM & HAAS is currently 0.05 to 0. It is about 10.

  When the chemical mechanical polishing pad according to the present embodiment has a laminate composed of a polishing layer and a support layer to be described later, or a laminate comprising another layer between the polishing layer and the support layer In the case of having a body, the thermal conductivity of the laminate is preferably 0.2 [W / m · K] or more, and more preferably 0.3 [W / m · K] or more. When the thermal conductivity of the laminate is 0.2 [W / m · K] or more, frictional heat generated when the object to be polished and the polishing layer rub against each other efficiently passes through another layer or a support layer. Can be diffused to a surface plate for fixing the polishing pad.

In the present invention, the thermal conductivity of the laminate can be calculated from the thickness of each layer and the thermal conductivity of each layer. For example, the entire chemical mechanical polishing pad has another layer (thickness: d2, thermal conductivity Λ2) between the polishing layer (thickness: d1, thermal conductivity Λ1) and the support layer (thickness: d3, thermal conductivity Λ3). Can be calculated by the following formula (3). In the case where the other layers are not included, the values of d2 and d2 / Λ2 may be calculated as 0 in the following formula (3).
Thermal conductivity [W / m · K] = (d1 + d2 + d3) / ((d1 / Λ1) + (d2 / Λ2) + (d3 / Λ3)) (3)
For reference, the thermal conductivity of a typical commercially available polishing pad such as “IC1000” manufactured by ROHM & HAAS is currently about 0.02 to 0.10. is there.

  It is more preferable to provide a cooling mechanism for controlling the temperature on the surface plate for fixing the chemical mechanical polishing pad. Thereby, not only can the temperature rise of the polishing layer be efficiently reduced, but also the temperature of the entire chemical mechanical polishing pad can be easily controlled.

1.1.4. Residual strain at the time of tension The residual strain at the time of tension of the polishing layer included in the chemical mechanical polishing pad according to the present embodiment is preferably 2% or more and 10% or less, more preferably 2% or more and 9% or less. preferable.

  Generally, fine holes and / or recesses are provided on the surface of the polishing layer, and polishing scraps and pad scraps are gradually accumulated therein, resulting in clogging and deterioration of polishing characteristics. Therefore, by dressing with a diamond grindstone (hereinafter also referred to as “diamond conditioning”), the clogged polishing layer surface is scraped off, and the same surface as the initial state below is exposed from the surface and used. During this diamond conditioning, fuzz and pad debris are generated on the surface of the polishing layer.

  FIG. 1 is a schematic diagram for explaining the concept of residual strain during tension of a polishing layer. 2A to 2E are enlarged views of a region I in FIG. 1 for explaining the concept of residual strain during tension of the polishing layer. As shown in FIG. 1, during the diamond conditioning, the dresser 20 rotates in the direction of the arrow in FIG. 1 to scrape the surface of the polishing layer 10. As shown in FIGS. 2A to 2B, when the polishing layer 10 is dressed, a part of the surface of the polishing layer 10 is pulled by the dresser 20 and extends. Then, as shown in FIG. 2C, a part of the surface of the polishing layer 10 is cut to generate pad scraps 10a. On the other hand, as shown in FIG. 2D, the portion 10b extended without being cut shrinks to return to the original state due to the elasticity of the polishing layer, but as shown in FIG. 2E, the fluff corresponding to the residual strain of the polishing layer is shrunk. Part 10b 'is generated. Thus, the residual strain at the time of tension | pulling of a polishing layer becomes an parameter | index which shows the degree of fluff on the surface of a polishing layer in the case of diamond conditioning.

  When the residual strain at the time of tension of the polishing layer is in the above range, generation of pad scraps due to diamond conditioning and fluffing on the surface of the polishing layer are reduced. Further, the deformation of the polishing layer with respect to the unevenness of the surface to be polished (the surface of the wafer or the like) can be reduced. Thereby, the flatness of the surface to be polished can be improved, and the generation of polishing defects can be reduced. If the residual strain at the time of tension of the polishing layer is less than 2%, pad scraps generated when the surface of the polishing layer is conditioned in diamond increase, which may increase polishing defects when mixed in the polishing process. Therefore, it is not preferable. On the other hand, if the residual strain at the time of tension of the polishing layer exceeds 10%, the surface of the polishing layer becomes fuzzy when the surface of the polishing layer is conditioned, and the deformation of the polishing layer with respect to the unevenness of the surface to be polished increases. Therefore, the flatness of the surface to be polished may be deteriorated, which is not preferable.

In the present invention, the residual strain at the time of tension of the polishing layer can be measured by a method based on “JIS K6270”. The test apparatus includes a fixed-side grip that holds one end of the test piece, a grip that holds the other end of the test piece and reciprocates, a drive device that reciprocates the grip at a constant frequency, and a fixed amplitude. The counter is configured to display the number of reciprocating motions. Specifically, two dumbbell-shaped test pieces are attached to the gripper, the test apparatus is moved, and stopped after 1 × 10 ³ repetitions. Stop at a position where no stress is applied to one test piece, and measure the distance between the marked lines of the test piece after 1 minute. Furthermore, after repeating 100 times, it measures similarly about another test piece. The test frequency is usually in the range of 1 to 5 Hz. Test before gauge length I _0, the gauge length I _n by non distorts after tensile repeatedly calculates the residual strain (%) at a tensile by the following equation (4).
Residual strain at tension (%) = ((I _n −I ₀ ) / I ₀ ) × 100 (4)

  Also, the temperature and humidity at the time of measurement are in accordance with “JIS K6250” “6.1 Standard temperature of test room” and “6.2 Standard humidity of test room”. That is, the standard temperature of the test room is 23 ° C., and the tolerance is ± 2 ° C. The standard humidity in the test room is 50% relative humidity, and the tolerance is ± 10%.

1.1.5. Volume Change Rate The polishing layer provided in the chemical mechanical polishing pad according to the present embodiment preferably has a volume change rate of 0.8% or more and 5% or less when the polishing layer is immersed in water at 23 ° C. for 24 hours. It is more preferably 1% or more and 3% or less.

  3A and 3B are schematic views for explaining the concept of the volume change rate in the polishing layer. Chemical mechanical polishing pads are constantly exposed to the slurry during the polishing operation. Then, the concave portion 30 of the polishing layer 10 that has been produced with a predetermined size and shape before water absorption as shown in FIG. 3A is caused by swelling due to water absorption as shown in FIG. The degree of fluffing may change. When the volume change rate when immersed in water is in the above range, the surface of the polishing layer is appropriately softened due to swelling due to water absorption, so that the generation of scratches can be reduced. When the volume change rate is less than the above range, since the swelling due to water absorption is small and the polishing layer surface is not sufficiently softened, the effect of reducing the generation of scratches cannot be sufficiently exhibited. When the volume change rate exceeds the above range, swelling due to water absorption becomes too large, and although the generation of scratches can be reduced, the flatness of the object to be polished is deteriorated. In particular, when a concave pattern is formed on the polished surface, if the swelling due to water absorption becomes too large, the shape and dimensions of the concave pattern change depending on the polishing time, and stable polishing characteristics may not be obtained. For this reason, it is preferable to swell in order to soften the surface of the polishing layer, but excessive swelling is not preferable because it causes deformation of the polishing surface.

The volume change rate of the polishing layer in the present invention can be measured by the following method based on “JIS K6258”. First, a polishing layer molded to a thickness of 2.8 mm is cut into a size of 2 cm × 2 cm and immersed in water at 23 ° C. for 24 hours. The mass in air before immersion (M1), the mass in water before immersion (M2), the mass in air after immersion (M3), and the mass in water after immersion (M4) are measured. To calculate the volume change rate.
Volume change rate (%) = (((M3-M4)-(M1-M2)) / (M1-M2)) × 100 (5)

1.1.6. Duro D hardness The duro D hardness of the polishing layer provided in the chemical mechanical polishing pad according to the present embodiment is preferably 50D or more and 80D or less, more preferably 55D or more and 75D or less, and 60D or more and 70D or less. It is particularly preferred.

  4A and 4B are schematic views for explaining the concept of duro D hardness in the polishing layer. As shown in FIG. 4A, when a polishing process is simulated to apply a load to the polishing layer 10 from above, the polishing layer 10 is bent as shown in FIG. 4B. The durro D hardness is an index indicating the degree of macro deflection of the polishing layer 10 when a weight is applied in the polishing step. This can also be understood from the measurement method described later. Accordingly, when the polishing layer has a duro D hardness in the above range, the polishing layer has an appropriate duro D hardness, so that the flatness of the surface to be polished is improved and the elastic deformation of the polishing layer with respect to the irregularities of the surface to be polished ( (Followability) becomes appropriate, so that polishing defects (scratches) can be reduced. When the durometer D hardness of the polishing layer is less than the above range, the flatness of the surface to be polished is deteriorated, which is not preferable. Further, if the duro D hardness of the polishing layer exceeds the above range, polishing defects (scratches) increase, which is not preferable.

  In the present invention, the duro D hardness of the polishing layer can be measured by a method based on “JIS K6253”. Specifically, the test piece is placed on a flat and solid surface, the pressure plate of the type D durometer is maintained parallel to the surface of the test piece, and the push needle is perpendicular to the surface of the test piece. Holding the type D durometer, the pressure plate is brought into contact with the test piece so as not to give an impact. The tip of the needle is measured at a position 12 mm or more away from the end of the test piece. After the pressure plate is brought into contact with the test piece, reading is performed 15 seconds later. The number of measurement points is measured 5 times at a position separated by 6 mm or more, and the median value is defined as Duro D hardness.

1.1.7. Surface hardness in wet condition of the polishing layer comprising the chemical mechanical polishing pad according to surface hardness present embodiment in the wet state, is preferably 2N / mm ² or more 10 N / mm ² or less, 3N / mm ² or more 9N / more preferably mm ² less, and particularly preferably 4N / mm ² or more 8N / mm ² or less. The surface hardness of the polishing layer in the wet state is an index representing the surface hardness of the polishing layer during actual use of CMP. 5A and 5B are schematic views for explaining the concept of surface hardness in the polishing layer. As shown in FIG. 5A, a very small probe 40 is pushed into the surface of the polishing layer 10. Then, as shown in FIG. 5B, the polishing layer 10 immediately below the probe 40 is deformed so as to be pushed out around the probe 40. Thus, the surface hardness is an index representing the degree of deformation or deflection of the extreme surface of the polishing layer. That is, in the Duro D hardness measurement which is a hardness measurement method in millimeters as shown in FIGS. 4A to 4B, data representing the macro hardness of the entire polishing layer is obtained, whereas polishing as shown in FIGS. In the measurement of the surface hardness of the layer in the wet state, data representing the micro hardness of the extreme surface of the polishing layer is obtained. The indentation depth of the polishing layer in actual use of CMP is 5 micrometers to 50 micrometers. Therefore, in order to determine the flexibility of the surface of the polishing layer, it is preferable to determine the surface hardness of the polishing layer in the wet state. When the surface hardness of the polishing layer in the wet state is in the above range, the flexibility of the extreme surface of the polishing layer becomes appropriate, so that polishing defects (scratches) can be reduced. If the surface hardness of the polishing layer in the wet state is less than the above range, the flatness of the surface to be polished may be deteriorated, which is not preferable. Further, if the surface hardness in the wet state of the polishing layer exceeds the above range, polishing defects (scratches) may increase, which is not preferable. In the present invention, the surface hardness in the wet state of the polishing layer is determined by using a nano indenter (product name: HM2000) manufactured by FISCHER in a polishing layer immersed in water at 23 ° C. for 4 hours, and pressing 300 mN. The universal hardness (HU).

1.1.8. The shape of the polishing layer and the concave portion The planar shape of the polishing layer is not particularly limited, but may be, for example, a circular shape. When the planar shape of the polishing layer is circular, the size is preferably 150 mm to 1200 mm in diameter, more preferably 500 mm to 1000 mm in diameter. The thickness of the polishing layer is preferably 0.5 mm to 5.0 mm, more preferably 1.0 mm to 4.0 mm, and particularly preferably 1.5 mm to 3.5 mm.

  A plurality of recesses may be formed on the polished surface. The concave portion holds the slurry supplied at the time of CMP, distributes it uniformly to the polishing surface, and temporarily retains wastes such as polishing scraps, pad scraps and used slurry to the outside. It has a function as a route for discharging.

  The depth of the recess is preferably 0.1 mm or more, more preferably 0.1 mm to 2.5 mm, and particularly preferably 0.2 mm to 2.0 mm. The width of the concave portion is preferably 0.1 mm or more, more preferably 0.1 mm to 5.0 mm, and particularly preferably 0.2 mm to 3.0 mm. In the polishing surface, the interval between adjacent recesses is preferably 0.05 mm or more, more preferably 0.05 mm to 100 mm, and particularly preferably 0.1 mm to 10 mm. The pitch, which is the sum of the width of the recess and the distance between adjacent recesses, is preferably 0.15 mm or more, more preferably 0.15 mm to 105 mm, and particularly preferably 0.6 mm to 13 mm. . The recesses can be formed with a certain interval in the above range. By forming the recess having the shape in the above range, a chemical mechanical polishing pad having an excellent effect of reducing scratches on the surface to be polished and having a long life can be easily manufactured.

  Each preferred range can be a combination of each. That is, for example, the depth is preferably 0.1 mm or more, the width is 0.1 mm or more, and the interval is 0.05 mm or more, the depth is 0.1 mm to 2.5 mm, and the width is 0.1 mm to 5. More preferably, the distance is 0 mm and the distance is 0.05 mm to 100 mm, the depth is 0.2 mm to 2.0 mm, the width is 0.2 mm to 3.0 mm, and the distance is particularly preferably 0.1 mm to 10 mm. .

  As a tool for processing the concave portion, a multi-blade tool having a shape described in JP-A-2006-167811, JP-A-2001-18164, JP-A-2008-183657, or the like can be used. The cutting blade of the tool used is selected from diamond, at least one metal element selected from metals of Group 4, 5, and 6 of the periodic table such as Ti, Cr, Zr, and V, and nitrogen, carbon, and oxygen. And a coating layer composed of at least one nonmetallic element. Furthermore, the number of coating layers is not limited to one, and a plurality of layers may be provided with different materials. The film thickness of such a coating layer is preferably from 0.1 to 5 μm, more preferably from 1.5 to 4 μm. In forming the coating layer, a known technique such as an arc ion plating apparatus can be selected and used as appropriate according to the tool material, coating material, and the like.

1.1.9. Manufacturing Method The polishing layer used in the present embodiment can be obtained by molding the above-described composition containing polyurethane. The composition can be kneaded with a known kneader or the like. Examples of the kneader include a roll, a kneader, a Banbury mixer, and an extruder (single screw, multi screw). As a method for molding the polishing layer from the composition, the composition plasticized at 120 ° C. to 230 ° C. may be molded by press molding, extrusion molding or injection molding and plasticizing / sheeting. The specific gravity and hardness can be controlled by appropriately adjusting the molding conditions.

  After molding in this way, a recess may be formed on the polished surface by cutting. Moreover, a concave part can be formed simultaneously with the rough shape of the polishing layer by molding the above-described composition using a mold in which a pattern to be a concave part is formed.

1.2. Support Layer Although the chemical mechanical polishing pad according to the present embodiment may be composed of only the polishing layer described above, a support layer may be provided on the surface opposite to the polishing surface of the polishing layer.

  The support layer is used for supporting the polishing layer on the polishing apparatus surface plate in the chemical mechanical polishing pad. The support layer may be an adhesive layer or a cushion layer having the adhesive layer on both sides.

  The adhesive layer can be made of, for example, an adhesive sheet. The thickness of the pressure-sensitive adhesive sheet is preferably 50 μm to 250 μm. By having a thickness of 50 μm or more, the pressure from the polishing surface side of the polishing layer can be sufficiently relaxed, and by having a thickness of 250 μm or less, it is uniform to the extent that the influence of unevenness is not exerted on the polishing performance. A chemical mechanical polishing pad having a sufficient thickness can be obtained.

  The material of the pressure-sensitive adhesive sheet is not particularly limited as long as the polishing layer can be fixed to the surface plate for a polishing apparatus, but is preferably an acrylic or rubber-based material having a lower elastic modulus than the polishing layer.

  The adhesive strength of the pressure-sensitive adhesive sheet is not particularly limited as long as the chemical mechanical polishing pad can be fixed to the surface plate for a polishing apparatus. However, when the adhesive strength of the pressure-sensitive adhesive sheet is measured according to the standard of “JIS Z0237”, the adhesive strength is preferable. Is 3 N / 25 mm or more, more preferably 4 N / 25 mm or more, and particularly preferably 10 N / 25 mm or more.

  As long as the cushion layer is made of a material whose hardness is lower than that of the polishing layer, the material is not particularly limited, and may be a porous body (foam) or a non-porous body. As a cushion layer, the layer which shape | molded foamed polyurethane etc. is mentioned, for example. The thickness of the cushion layer is preferably 0.1 mm to 5.0 mm, more preferably 0.5 mm to 2.0 mm.

  The thermal conductivity of the support layer is also preferably 0.2 [W / m · K] or more, and more preferably 0.3 [W / m · K] or more. If the thermal conductivity of the support layer is 0.2 [W / m · K] or more, the frictional heat generated when the surface to be polished and the surface of the polishing pad rub against each other is efficiently determined via the support layer. Can be diffused to the board. As a result, the frictional heat generated in the polishing layer can be efficiently removed, so that even when CMP is performed for a long time, the temperature rise in the polishing layer is reduced and stable polishing characteristics are maintained. Can do.

  In the present invention, the thermal conductivity of the support layer can be measured by the same method as the method for measuring the thermal conductivity of the polishing layer described above. For reference, the thermal conductivity of a support layer of a typical commercially available polishing pad such as a urethane pad having a foam type polishing layer that is currently on the market, such as “IC1000” manufactured by ROHM & HAAS, is 0.01 to 0.10. Degree.

  The compressibility of the support layer is preferably 5% or more, and more preferably 6% or more. When polishing an object to be polished such as a silicon wafer, the pressing pressure per unit area is different between the center and the end, and the pressing pressure at the end tends to be larger. As a result, the difference between the polishing rate at the center of the object to be polished and the polishing rate at the end becomes large, and it becomes difficult to polish the surface to be polished at a uniform polishing rate. However, if the compressibility of the support layer is within the above range, the support layer can be effectively deformed to reduce an increase in pressing pressure at the end, so that the entire surface to be polished can be polished at a uniform polishing rate. It becomes possible to do. When the compressibility of the polishing layer is in the above range, the pressing pressure exerted on the object to be polished becomes too low, the polishing rate is significantly reduced, and the flatness of the surface to be polished may be impaired. Therefore, in order to achieve the object of the present invention, it is desirable that the compressibility of the support layer is in the above range.

2. Chemical Mechanical Polishing Method The chemical mechanical polishing method according to the present embodiment is characterized in that chemical mechanical polishing is performed using the above-described chemical mechanical polishing pad. The chemical mechanical polishing pad described above is formed from a composition containing polyurethane, and has a polishing layer having a specific gravity in a specific range and thermal conductivity. Therefore, according to the chemical mechanical polishing method according to the present embodiment, it is possible to achieve both improvement in flatness of the surface to be polished and reduction in polishing defects (scratches) in the CMP process, and in CMP for a long time. In addition, stable polishing characteristics can be maintained.

  In the chemical mechanical polishing method according to the present embodiment, a commercially available chemical mechanical polishing apparatus can be used. Examples of commercially available chemical mechanical polishing apparatuses include, for example, model “EPO-112”, model “EPO-222” (manufactured by Ebara Corporation); model “LGP-510”, model “LGP-552” (and above, Wrap Master SFT); model “Mirra”, model “Reflexion LK” (applied by Applied Materials) and the like.

  Further, as the slurry, an optimal one can be appropriately selected according to the object to be polished (copper film, insulating film, low dielectric constant insulating film, etc.).

3. EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

3.1. Manufacture of chemical mechanical polishing pads 3.1.1. Example 1
100 parts by mass of non-alicyclic thermoplastic polyurethane (manufactured by BASF, trade name “Elastollan 1174D”, hardness 70D), β-cyclodextrin (manufactured by Shimizu Minato Sugar Co., Ltd., trade name “Dexipal β- 100 ”, average particle size 20 μm) 29 parts by mass were kneaded with a rudder adjusted to 200 ° C. to prepare a thermoplastic polyurethane composition. The produced thermoplastic polyurethane composition was compression molded at 180 ° C. in a press mold to produce a cylindrical molded body having a diameter of 845 mm and a thickness of 3.2 mm. Next, the surface of the molded body is polished with sandpaper, the thickness is adjusted, and a concentric circle having a width of 0.5 mm, a depth of 1.0 mm, and a pitch of 1.5 mm is obtained by a cutting machine (manufactured by Kato Machine Co., Ltd.). A polishing layer having a diameter of 600 mm and a thickness of 2.5 mm was obtained by forming a concave portion and cutting the outer periphery. A double-sided tape # 422JA (manufactured by 3M) was laminated to the surface of the polishing layer thus prepared where no recess was formed, to prepare a chemical mechanical polishing pad.

3.1.2. Example 2
First, a polishing layer was obtained in the same manner as in Example 1. Double-sided tape # 550PS5 (manufactured by Sekisui Chemical Co., Ltd.) is laminated to the surface of the polishing layer produced in this way, where no recess is formed, and a sheet-like urethane (trade name “Nippray EXY”, which becomes a support layer on the tape surface. ”, Manufactured by Nippon Hojo Co., Ltd.), and a double-sided tape # 442JA (manufactured by 3M) was laminated to prepare a chemical mechanical polishing pad.

3.1.3. Examples 3 and 4
The chemical mechanical polishing pads of Examples 3 and 4 were produced in the same manner as in Example 1 except that the types and contents of the components of the composition were changed to those shown in Table 1.

3.1.4. Example 5
First, a polishing layer was obtained in the same manner as in Example 1. A double-sided tape # 550PS5 (manufactured by Sekisui Chemical Co., Ltd.) is laminated to the surface of the polishing layer thus prepared where no recess is formed, and the support layer having the compressibility and thermal conductivity shown in Table 1 is laminated. The chemical mechanical polishing pad was prepared by laminating and laminating double-sided tape # 442JA (manufactured by 3M). In addition, the support layer having the compressibility and thermal conductivity shown in Table 1 is obtained by adding spherical graphite (trade name “WF-15C”) to hydrogenated ethylene-butylene block copolymer (trade name “DYNARON”, manufactured by JSR Corporation). , Manufactured by Chuetsu Graphite Industries Co., Ltd.) was added by kneading with a kneader and adding a suitable amount so as to achieve the compressibility and thermal conductivity shown in Table 1 and preparing a sheet.

3.1.5. Example 6
A chemical mechanical polishing pad was produced in the same manner as in Example 5. In addition, the support layer having the compressibility and thermal conductivity shown in Table 1 is obtained by adding hydrogenated ethylene-butylene block copolymer (trade name “DYNARON”, manufactured by JSR Corporation) to spherical alumina (trade name “DAM-70”). Electrochemical Industry Co., Ltd.) was prepared by kneading with a kneader and adding a suitable amount so that the compression ratio and thermal conductivity shown in Table 1 were obtained.

3.1.6. Example 7
A chemical mechanical polishing pad was produced in the same manner as in Example 2 except that Sunmorphy (manufactured by Sun Delta Co., Ltd.) was used as the support layer.

3.1.7. Comparative Example 1
A commercially available chemical mechanical polishing pad (manufactured by ROHM & HAAS, trade name “IC1000”, a polishing layer made of thermally crosslinked polyurethane resin) was used. When the physical properties of the polishing layer were measured by the method described later, the specific gravity was 0.81 and the thermal conductivity was 0.05 W / m · K.

3.1.8. Comparative Example 2
1,2-polybutadiene (manufactured by JSR Corporation, trade name “RB830”, hardness 47D), 100 parts by weight as water-soluble particles, β-cyclodextrin (manufactured by Shimizu Minato Sugar Co., Ltd., trade name “Dexipal β-100”, A composition in which 38 parts by mass of an average particle size of 20 μm was mixed was obtained. Example 1 After obtaining 1 part by mass of an organic peroxide (manufactured by NOF Corporation, trade name “Park Mill D-40”) and kneading with 100 parts by mass of the obtained composition, Example 1 was obtained. In the same manner as above, a polishing layer made of a water-soluble particle-containing thermally crosslinked polybutadiene resin was obtained. A double-sided tape # 550PS5 (manufactured by Sekisui Chemical Co., Ltd.) is laminated on the surface of the polishing layer thus prepared, on which no recess is formed, and a high-density thin sheet hydrogenated ethylene that serves as a support layer on the tape surface. A butylene block copolymer (trade name “DAYNARON”, manufactured by JSR Corporation) was attached, and double-sided tape # 442JA (manufactured by 3M Corporation) was laminated to prepare a chemical mechanical polishing pad.

In addition, the abbreviation of each component in Table 1 is as follows.
"PU1-1": non-alicyclic thermoplastic polyurethane (manufactured by BASF, trade name "Elastolan 1174D", hardness 70D)
"PU2-1": Alicyclic thermoplastic polyurethane (manufactured by BASF, trade name "Elastolan NY1197A", hardness 61D)
“Β-CD”: β-cyclodextrin (average particle size 20 μm, manufactured by Shimizu Minato Sugar Co., Ltd., trade name “Dexipal β-100”)
"Heat-crosslinked polybutadiene resin": 1,2-polybutadiene (hardness 47D, manufactured by JSR Corporation, trade name "RB830")
"Organic peroxide": Dicumyl peroxide (manufactured by NOF Corporation, trade name "Park Mill D-40", crosslinking agent)

3.2. Measurement of physical properties of polishing layer 3.2.1. Specific gravity The specific gravity was measured for the polishing layer prepared in “3.1. Production of Chemical Mechanical Polishing Pad” and the polishing layer of IC1000. The specific gravity of the polishing layer was measured according to “JIS Z8807”. The results are also shown in Table 1.

3.2.2. Thermal conductivity Thermal conductivity was measured for the polishing layer produced in “3.1. Production of Chemical Mechanical Polishing Pad” and the polishing layer of IC1000. The thermal conductivity was measured as follows. A test piece was placed on the sensor, and a 50 g weight was placed on top of a fixing jig equipped with a micro heater. The thermal diffusion coefficient D was measured from the attenuation of the amplitude and the phase delay generated when the temperature wave generated from the surface of the microheater diffused in the thickness direction and reached the back surface. From the obtained thermal diffusion coefficient D, the specific heat ρ of the test piece, and the specific gravity Cp, the thermal conductivity (W / m · K) was calculated by the following formula (2). The results are also shown in Table 1.
Thermal conductivity (W / m · K) = D / (ρ × Cp) (2)

3.2.3. Residual strain at the time of tension A test piece was prepared from the portion of the polishing layer prepared in “3.1. Manufacture of chemical mechanical polishing pad” and the concave portion of each polishing layer of the IC1000, and the residual strain at the time of tension was measured. It was measured. The residual strain at the time of tension was measured according to “JIS K6270”. The temperature at the time of measurement was 23 ° C., and the humidity was 50% in relative humidity. The results are also shown in Table 1.

3.2.4. Volume Change Rate The volume change rate was measured for the polishing layer produced in “3.1. Production of Chemical Mechanical Polishing Pad” and the polishing layer of IC1000. The volume change rate of the polishing layer was measured by the following method based on “JIS K6258”. First, a polishing layer molded to a thickness of 2.8 mm was cut into a 2 cm × 2 cm square and used as a measurement sample. This measurement sample was immersed in water at 23 ° C. for 24 hours. Electronic balance (Made by Chow Balance Co., Ltd.) The mass in air before immersion (M1), the mass in water before immersion (M2), the mass in air after immersion (M3), and the mass in water after immersion (M4) , Model “JP-300”), and the volume change rate was calculated by the following formula (5). The results are also shown in Table 1.
Volume change rate (%) = (((M3-M4)-(M1-M2)) / (M1-M2)) × 100 (5)

3.2.5. Duro D hardness Duro D hardness was measured for the polishing layer produced in “3.1. Production of Chemical Mechanical Polishing Pad” and the polishing layer of IC1000. The Duro D hardness of the polishing layer was measured according to “JIS K6253”. The results are also shown in Table 1.

3.2.6. Surface Hardness in Wet State Regarding the polishing layer produced in “3.1. Production of Chemical Mechanical Polishing Pad” and the polishing layer of IC1000, the surface hardness in the wet state of the polishing layer was measured. The surface hardness in the wet state of the polishing layer was determined by using a nanoindenter (manufactured by FISCHER, model “HM2000”) for the polishing layer immersed in water at 23 ° C. for 4 hours, and the universal hardness (HU) ) Was measured as the surface hardness. The results are also shown in Table 1.

3.3. Measurement of physical properties of support layer 3.3.1. Compressibility For the support layer used in “3.1. Production of Chemical Mechanical Polishing Pad” and the support layer peeled off from the IC1000, small pieces cut into squares each having a side of 2 cm were prepared. COMPRESIVE ELESTICITY TESTER Model. Using SE-15 (manufactured by Intec Co., Ltd.), placing the small piece on the probe of the measuring apparatus, applying a load of 10 gf and 600 gf, measuring the thickness after leaving the load constant for 1 minute, and measuring the temporary small piece The thickness was taken. Moreover, it measured similarly also in the state of a blank, without mounting | wearing a small piece, and measured the thickness in the state of a blank. The compression ratio was calculated from the measurement result by the following formula (6).
| Tentative piece thickness at 10 gf—blank thickness at 10 gf | = support layer thickness at 10 gf | temporary piece thickness at 600 gf—blank thickness at 600 gf | = support layer thickness at 600 gf (support layer at 10 gf) Thickness—support layer thickness at 600 gf) / 10 support layer thickness at 10 gf × 100 = compression ratio (%) (6)

3.4. Evaluation of Chemical Mechanical Polishing The chemical mechanical polishing pad manufactured in “3.1. Manufacturing of Chemical Mechanical Polishing Pad” is attached to a chemical mechanical polishing apparatus (Ebara Manufacturing Co., Ltd., model “EPO-112”), and a dresser. Dressing was performed for 30 minutes under the conditions of a table rotation speed of 20 rpm, a dressing rotation speed of 19 rpm, and a dressing load of 5.1 kgf (made by Allied, trade name “# 325-63R”). Thereafter, chemical mechanical polishing was performed using the dressed chemical mechanical polishing pad under the following conditions to evaluate the polishing characteristics.
-Head rotation speed: 60 rpm
Head load: 3 psi (20.6 kPa)
・ Table rotation speed: 61rpm
・ Slurry supply speed: 300 cm ³ / min ・ Slurry: CMS8401 / CMS8452 (manufactured by JSR Corporation)

3.4.1. Evaluation of flatness As a polishing object, a PETEOS film was sequentially laminated on a silicon substrate by 5,000 mm, and then a “SEMATECH 854” mask pattern was processed thereon. Then, a 250 mm tantalum nitride film and a 1,000 mm copper seed were formed. A test substrate in which a film and a 10,000-thick copper film were sequentially laminated was used.

  Under the conditions described in “3.4. Evaluation of Chemical Mechanical Polishing”, the object to be polished was subjected to chemical mechanical polishing for 1 minute, and the film thickness before and after the treatment was measured by an electroconductive film thickness measuring instrument (manufactured by KLA-Tencor Corporation). , Format “Omnimap RS75”), and the polishing rate was calculated from the film thickness before and after the treatment and the polishing treatment time. Then, the end point time at which the Cu is cleared is calculated as the time from the start of polishing to the end point detected by the change of the table torque current, and 1.2 times the end point detection time for the patterned wafer. After polishing, a precision step gauge (manufactured by KLA-Tencor Corporation) is used for a portion in which a pattern in which copper wiring portions having a width of 100 μm and insulating portions having a width of 100 μm are alternately continued in a direction perpendicular to the length direction is 3.0 mm. Dishing was evaluated by measuring the amount of depression (hereinafter also referred to as “dishing amount”) of the copper wiring having a wiring width of 100 μm using the format “HRP-240”), and used as a flatness index. The results are also shown in Table 1. The dishing amount is preferably less than 400 Å, more preferably less than 300 Å, and particularly preferably less than 200 Å.

3.4.2. Evaluation of Scratches On the polished surface of the patterned wafer after polishing, the number of scratches on the entire surface of the wafer was measured using a wafer defect inspection apparatus (model “KLA2351” manufactured by KLA-Tencor Corporation). The results are also shown in Table 1. The number of scratches is preferably less than 50, more preferably less than 30, and particularly preferably less than 20.

3.4.3. Evaluation of Polishing Rate Chemical mechanical polishing was performed under the same conditions as in “3.3. Evaluation of Chemical Mechanical Polishing” using an 8-inch wafer with a PETEOS film having a thickness of 1000 nm as an object to be polished. Note that the PETEOS film is a silicon oxide film formed by a chemical vapor deposition method using tetraethyl silicate (TEOS) as a raw material and using plasma as an acceleration condition.

For the wafer with 12 inch PETEOS film as the object to be polished, optical interference type film thickness measuring device (manufactured by Nanometrics Japan Co., Ltd., model “ Nano Spec 6100 ") was used to measure the thickness of the PETEOS film before and after chemical mechanical polishing. From this measurement result, the polishing rate was calculated by the following formulas (7) and (8).
Polishing amount (nm) = film thickness before polishing (nm) −film thickness after polishing (nm) (7)
Polishing rate (nm / min) = average value of polishing amount at 33 points (nm) / polishing time (min) (8)
The evaluation results of the polishing rate are also shown in Table 1. When the polishing rate was 200 nm / min or more, it was determined that the polishing characteristics were good, and when the polishing rate was less than 200 nm / min, it was determined that the polishing characteristics were poor.

3.4.4. Evaluation of Durability Based on the method of “3.4.3. Evaluation of Polishing Rate”, the rate of change of the polishing rate when the wafer is continuously polished is calculated by the following formula (9) to determine the durability of the polishing layer. Sex was evaluated. Specifically, in order to simulate a state in which the wafer is continuously polished, the friction state between the dresser and the pad by dressing is continued for 10 hours, and the rate of change is calculated from the polishing rate before and after that by the following formula (9). Was calculated. When the rate of change of the polishing rate is less than 5%, it is judged that the durability is good (“◯” in Table 1), and when it is 5% or more and less than 10%, the durability is acceptable (Table 1). In this case, it was determined that the durability was poor (“×” in Table 1).
Polishing rate change rate (%) = ((polishing rate after 10 hours dressing−initial polishing rate) / initial polishing rate) × 100 (9)

3.4.5. Evaluation of rate of change in edge portion polishing rate Chemical mechanical polishing was performed under the same conditions as in “3.4. Evaluation of chemical mechanical polishing”, using an 8-inch wafer with a TEOS film having a thickness of 1000 nm as an object to be polished. For the wafer with 8 inch PETEOS film as the object to be polished, an optical interference type film thickness measuring device (model number “Nano Spec 6100” manufactured by Nanometrics Japan Co., Ltd.) for 0 mm, 4 mm, 8 mm, and 98 mm in the diameter direction from the wafer center. Was used to measure the thickness of the PETEOS film before and after chemical mechanical polishing. From this measurement result, the change rate of the edge portion RR was calculated by the following equation.
Polishing amount (nm) = film thickness before polishing (nm) −film thickness after polishing (nm)
Central portion polishing amount (nm) = 0 mm, average value of 4 mm, 8 mm polishing amount Central portion polishing rate (nm / min) = central portion polishing amount (nm) / polishing time (min)
Edge portion polishing amount (nm) = average value of 98 mm polishing amount Edge portion polishing rate (nm / min) = edge portion polishing amount (nm) / polishing time (min)
Change rate of edge portion polishing rate = | (edge portion polishing rate−center portion polishing rate) / center portion polishing rate |
Note that the rate of change in the edge portion polishing rate is preferably as small as possible. Table 1 also shows the evaluation results of the rate of change in the edge portion polishing rate.

3.5. Evaluation result of chemical mechanical polishing pad According to Table 1, since the polishing layer of the chemical mechanical polishing pad according to Examples 1 to 7 has a thermal conductivity of 0.20 [W / m · K] or more, Accumulation of frictional heat generated when the surface to be polished and the polishing layer rub against each other can be reduced. By this action, it is considered that the durability of the polishing layer of the chemical mechanical polishing pad according to Examples 1 to 7 was good. In addition, favorable results were obtained in both of the two polishing properties of flatness and scratch.

  On the other hand, in the chemical mechanical polishing pads according to Comparative Examples 1 and 2, one or more of the three items of polishing characteristics described above were defective.

  Since the thermal conductivity of the polishing layer is as low as 0.10 [W / m · K] in the case of a polishing layer having a thermally crosslinked polyurethane having a foamed structure like the chemical mechanical polishing pad according to Comparative Example 1, polishing is performed. There is a tendency for frictional heat to accumulate in the layer. For this reason, it is considered that the durability of the polishing layer of the chemical mechanical polishing pad according to Comparative Example 1 is poor. In addition, the chemical mechanical polishing pad according to Comparative Example 1 has a laminated body of a polishing layer and a support layer, and the thermal conductivity of the laminated body is as low as 0.05 [W / m · K]. It is thought that the diffusion of frictional heat is made difficult.

  Further, in the case of a polishing layer having polybutadiene as in the chemical mechanical polishing pad according to Comparative Example 2, the thermal conductivity is sufficiently high as 0.24 [W / m · K], but the surface has poor hydrophilicity and polishing. Since the heat transfer to the slurry on the surface of the layer was insufficient, the durability of the polishing layer was poor. In addition, the polishing characteristics of the scratch were inferior.

  As is clear from the results of the above Examples and Comparative Examples, the chemical mechanical polishing pad according to the present invention provides a flatness and a balance by regulating the balance between the specific gravity of the polishing layer containing polyurethane and the thermal conductivity. A chemical mechanical polishing pad excellent in polishing characteristics such as scratch performance and durability was able to be produced.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 10 ... Polishing layer, 10a ... Pad waste, 10b ... Extended part, 10b '... Fluff part, 20 ... Dresser, 30 ... Recessed part, 40 ... Probe

Claims (8)

Having a polishing layer formed from a composition containing polyurethane;
A chemical mechanical polishing pad, wherein the polishing layer has a specific gravity of 1.1 or more and 1.3 or less, and a thermal conductivity of the polishing layer is 0.2 [W / m · K] or more. . It has a laminate in which a support layer is formed on one surface side of the polishing layer,
The chemical mechanical polishing pad according to claim 1, wherein the laminate has a thermal conductivity of 0.2 [W / m · K] or more.   The chemical mechanical polishing pad according to claim 1 or 2, wherein a residual strain at the time of tension of the polishing layer is 2% or more and 10% or less.   The chemical mechanical polishing according to any one of claims 1 to 3, wherein a volume change rate when the polishing layer is immersed in water at 23 ° C for 24 hours is 0.8% or more and 5.0% or less. pad.   The chemical mechanical polishing pad according to claim 2, wherein the compressibility of the support layer is 5% or more.   The chemical mechanical polishing pad according to any one of claims 1 to 5, wherein the polyurethane is a thermoplastic polyurethane.   The chemical mechanical polishing pad according to any one of claims 1 to 6, wherein the composition further comprises water-soluble particles.   A chemical mechanical polishing method, wherein chemical mechanical polishing is performed using the chemical mechanical polishing pad according to any one of claims 1 to 7.

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