JP2006114885A - Pad and method for chemical mechanical polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing pad that can control scratch generation on a polishing surface during a chemical polishing process and give a high-quality polishing surface, and chemical mechanical polishing method that gives a high-quality polishing surface using the chemical machinery polishing pad. <P>SOLUTION: When the storage modulus of a polishing substrate is measured at 30°C and 60°C under the following conditions of initial loading: 100 g, maximum distortion: 0.01% and frequency: 0.2 Hz, the storage elastic modulus E' at 30°C is no more than 120 MPas and the ratio between the storage elastic modulus at 30°C and that at 60°C, or E'(30°C)/E'(60°C) is no less than 2.5. Meanwhile, the chemical mechanical polishing method is based on the use of the foregoing chemical mechanical polishing pad. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

In recent years, in the formation of semiconductor devices, etc., a surface having excellent flatness can be formed on a silicon substrate or a silicon substrate (hereinafter referred to as “semiconductor wafer”) on which wirings, electrodes, etc. are formed. As a polishing method, a chemical mechanical polishing method (Chemical Mechanical Polishing, generally abbreviated as “CMP”) has attracted attention. In the chemical mechanical polishing method, a chemical mechanical polishing aqueous dispersion (an aqueous dispersion in which abrasive grains are dispersed) is allowed to flow down on the pad surface while sliding the chemical mechanical polishing pad and the surface to be polished. This is a technique for polishing. In this chemical mechanical polishing method, it is known that the polishing result greatly depends on the properties and characteristics of the chemical mechanical polishing pad, and various chemical mechanical polishing pads have been proposed.
For example, a polyurethane foam containing fine bubbles is used as a chemical mechanical polishing pad, and polishing is performed by holding a chemical mechanical polishing aqueous dispersion in a hole (hereinafter referred to as “pore”) opened on the surface of the pad. The chemical mechanical polishing pad has been known for a long time. (See Patent Documents 1 to 3).
In recent years, a polishing pad in which a water-soluble polymer is dispersed in a matrix resin has been disclosed as a polishing pad capable of forming a pore without using a foam (see Patent Documents 4 to 7). In this technique, a water-soluble polymer dispersed in a matrix resin is dissolved in contact with a chemical mechanical polishing aqueous dispersion or water during polishing to form pores.

By the way, when polishing the surface to be polished by the chemical mechanical polishing method, sometimes when the abrasive grains contained in the chemical mechanical polishing aqueous dispersion used are aggregated into coarse particles, There is a case where a scratch-like defect called “scratch” is generated on the surface of the surface to be polished, and improvement is demanded. In addition, since the polishing pad composition is hard, it causes scratches, and there are cases where scratches occur due to a combination of the agglomeration of abrasive grains and the hardness of the polishing pad composition, and improvements are required.
In order to solve such a problem, a multilayer pad in which a flexible buffer layer is laminated on the back surface (non-polished surface) of the pad has been proposed (see Patent Document 8). However, although the multi-layer pad improves the above-mentioned problem to some extent, it has not reached a radical solution, and the manufacturing process becomes complicated, resulting in increased costs and quality control problems. It is known.

On the other hand, for the purpose of improving the performance of a semiconductor device, attention has been paid to using an insulating film having a lower dielectric constant instead of the conventional insulating film (SiO ₂ film). Examples of the low dielectric constant insulating film include silsesquioxane (relative dielectric constant: about 2.6 to 3.0), fluorine-added SiO ₂ (relative dielectric constant: about 3.3 to 3.5), polyimide Resin (relative permittivity: about 2.4 to 3.6, manufactured by Hitachi Chemical Co., Ltd., trade name “PIQ”, Allied Signal, trade name “FLARE”, etc.), benzocyclobutene (relative permittivity) About 2.7, manufactured by Dow Chemical, trade name “BCB”, etc., hydrogen-containing SOG (relative dielectric constant: about 2.5 to 3.5) and organic SOG (relative dielectric constant: about 2.9, Hitachi) Kasei Kogyo Co., Ltd., trade name “HSGR7”, etc.) have been developed. However, these insulating films generally have lower mechanical strength than SiO ₂ films, and are soft and brittle. Therefore, when the chemical mechanical polishing is performed using a conventionally known chemical mechanical polishing pad, the conventionally known insulating film There is a problem that scratches are more likely to occur than in the case of polishing, and that peeling occurs at the interface between the insulating film having a low dielectric constant, which is the surface to be polished, and the underlying film.
Further, an object to be polished is formed by laminating an insulating film having a low dielectric constant as described above on a semiconductor substrate, forming a groove, and then depositing a metal as a wiring material on the entire surface of the grooved substrate on which a barrier metal film is formed. In the case where the low dielectric constant insulating film is not exposed on the polished surface, that is, in the stage where only the metal that is the wiring material is chemically mechanically polished, the lower low dielectric constant insulating film is There is a problem that peeling may occur at either the upper or lower film interface.
JP-A-11-70463 JP-A-8-216029 JP-A-8-39423 Japanese National Patent Publication No. 8-500622 JP 2000-34416 A JP 2000-33552 A JP 2001-334455 A JP 2002-36097 A

  The present invention solves the above-mentioned problems, and its purpose is to suppress the generation of scratches on the surface to be polished of the object to be polished and the peeling of the insulating film having a low dielectric constant in the chemical mechanical polishing process. It is an object of the present invention to provide a chemical mechanical polishing pad capable of providing a polishing surface and a chemical mechanical polishing method for providing a high-quality polished surface using the chemical mechanical polishing pad.

According to the present invention, the above-mentioned problem of the present invention is, firstly, the following condition initial load: 100 g
Maximum strain: 0.01%
Frequency: 0.2Hz
When the storage elastic modulus at 30 ° C. and 60 ° C. of the polishing substrate was measured, the storage elastic modulus E ′ (30 ° C.) at 30 ° C. was 120 MPa or less, and the storage elastic modulus E ′ (30 ° C.) at 30 ° C. And the storage elastic modulus E ′ at 60 ° C. (60 ° C.) (E ′ (30 ° C.) / E ′ (60 ° C.)) is achieved by a chemical mechanical polishing pad having a ratio of 2.5 or more.

  The above object of the present invention is secondly achieved by a chemical mechanical polishing method characterized in that a chemical mechanical polishing step is performed using the above chemical mechanical polishing pad.

  ADVANTAGE OF THE INVENTION According to this invention, the generation | occurrence | production of the scratch of the to-be-polished surface in a chemical mechanical polishing process can be suppressed, the chemical mechanical polishing pad which can give a high quality to-be-polished surface, and the high quality performed using the chemical mechanical polishing pad A chemical mechanical polishing method for providing a surface to be polished is provided.

The chemical mechanical polishing pad of the present invention has at least a polishing substrate. The polishing substrate is subjected to the following initial load condition: 100 g
Maximum strain: 0.01%
Frequency: 0.2Hz
When the storage elastic modulus at 30 ° C. and 60 ° C. was measured, the storage elastic modulus E ′ (30 ° C.) at 30 ° C. was 120 MPa or less, and the storage elastic modulus E ′ (30 ° C.) at 30 ° C. and 60 ° C. The storage elastic modulus E ′ (60 ° C.) ratio (E ′ (30 ° C.) / E ′ (60 ° C.)) is 2.5 or more.

The storage elastic modulus E ′ (30 ° C.) at 30 ° C. is preferably 30 to 120 MPa, and the ratio of the storage elastic modulus E ′ (30 ° C.) at 30 ° C. to the storage elastic modulus E ′ (60 ° C.) at 60 ° C. (E ′ (30 ° C.) / E ′ (60 ° C.)) is preferably 2.5 to 10. The storage elastic modulus E ′ (60 ° C.) at 60 ° C. is preferably 3 to 48 MPa.
The polishing base of the chemical mechanical polishing pad of the present invention preferably has a Shore D hardness of 35 or more. The Shore D hardness is more preferably 35-100, and still more preferably 35-70. By setting the Shore D hardness in this range, the load pressure on the object to be polished can be increased, and the polishing rate can be improved accordingly.

The polishing substrate of the chemical mechanical polishing pad of the present invention may be made of any material as long as it can exhibit the function as the chemical mechanical polishing pad as long as it has the above requirements. Among the functions as a chemical mechanical polishing pad, in particular, when pores (fine pores) have functions such as holding the chemical mechanical polishing aqueous dispersion during chemical mechanical polishing and temporarily retaining polishing debris It is preferable that it is formed by. Therefore, (I) a water-insoluble member and a material composed of water-soluble particles dispersed in the water-insoluble member, or (II) a material composed of a water-insoluble member and pores dispersed in the water-insoluble member. It is preferable to provide.
Of these, the material (I) is formed into a water-insoluble member by the water-soluble particles coming into contact with the chemical mechanical polishing aqueous dispersion and dissolving or swelling during the chemical mechanical polishing step. It is possible to hold the chemical mechanical polishing aqueous dispersion in the pores, while the material (II) has a holding capacity of the chemical mechanical polishing aqueous dispersion or the like in the portion formed in advance as pores. .

  Hereinafter, these materials will be described in detail.

(I) Material comprising water-insoluble member and water-soluble particles dispersed in water-insoluble member (A) Water-insoluble member The material constituting the water-insoluble member (A) is not particularly limited. An organic material is preferably used because it can be easily formed into a shape and properties, and can be provided with appropriate hardness, appropriate elasticity, and the like. Examples of the organic material include thermoplastic resin, elastomer or raw rubber, and cured resin.
Examples of the thermoplastic resin include olefin resins (for example, polyethylene and polypropylene), styrene resins (for example, polystyrene), acrylic resins (for example, (meth) acrylate resins), vinyl ester resins (however, (meth)). Examples thereof include those not corresponding to acrylate resins), polyester resins (excluding those corresponding to vinyl ester resins), polyamide resins, fluororesins, polycarbonate resins, polyacetal resins, and the like.

  Examples of the elastomer or raw rubber include diene elastomers (for example, 1,2-polybutadiene), olefin elastomers (for example, dynamically cross-linked ethylene-propylene rubber and polypropylene resin, etc.), urethane elastomers, and urethane rubbers. (For example, urethane rubber), styrene-based elastomer (for example, styrene-butadiene-styrene block copolymer (hereinafter sometimes referred to as “SBS”), hydrogenated product of styrene-butadiene-styrene block copolymer (hereinafter, referred to as “SBS”). Etc.)), conjugated diene rubbers (for example, high cis butadiene rubber, low cis butadiene rubber, isoprene rubber, styrene-butadiene rubber, styrene-isoprene rubber, acrylonitrile-butadiene rubber, chloroprene). Etc.), ethylene-α-olefin rubber (for example, ethylene-propylene rubber, ethylene-propylene-nonconjugated diene rubber, etc.), butyl rubber, and other rubbers (for example, silicone rubber, fluorine rubber, nitrile rubber, chlorosulfonated polyethylene, acrylic rubber) , Epichlorohydrin rubber, polysulfide rubber, etc.).

Examples of the curable resin include a thermosetting resin and a photocurable resin. Specific examples of these include urethane resin, epoxy resin, unsaturated polyester resin, polyurethane-urea resin, urea resin, silicon resin, phenol resin and the like.
These organic materials may be used alone or in combination of two or more.
These organic materials may be modified so as to have an appropriate functional group. Examples of suitable functional groups include groups having an acid anhydride structure, carboxyl groups, hydroxyl groups, epoxy groups, amino groups, and the like.

  These organic materials are preferably partially or wholly crosslinked. When the water-insoluble member contains a crosslinked organic material, an appropriate elastic recovery force is imparted to the water-insoluble member, and displacement due to shear stress applied to the chemical mechanical polishing pad during chemical mechanical polishing can be suppressed. . In addition, the water-insoluble member is excessively stretched and plastically deformed to fill the pores during the chemical mechanical polishing process and dressing (the “sharpening” process of the chemical mechanical polishing pad performed alternately or simultaneously with the chemical mechanical polishing). In addition, it is possible to effectively suppress the surface of the chemical mechanical polishing pad from being fuzzed excessively. Therefore, a chemical mechanical polishing pad that can efficiently form pores at the time of dressing, can prevent deterioration of the retainability of the chemical mechanical polishing aqueous dispersion during polishing, and can maintain polishing flatness for a long time with less fuzzing. It will be possible to obtain.

  Examples of the crosslinked organic material include a crosslinked thermoplastic resin and a crosslinked elastomer or a crosslinked rubber (herein, “crosslinked rubber” means a crosslinked product of the “raw rubber”). More preferably, it contains at least one selected from the group consisting of a crosslinked diene elastomer, a crosslinked styrene elastomer, and a crosslinked conjugated diene rubber. At least one selected from crosslinked 1,2-polybutadiene, crosslinked SBS, crosslinked SEBS, crosslinked styrene butadiene rubber, crosslinked styrene-isoprene rubber and crosslinked acrylonitrile-butadiene rubber. It is particularly preferred to contain a crosslinked 1,2-polybutadiene It is especially preferred to contain at least one selected from among crosslinked SBS and crosslinked SEBS.

  When a part of the organic material is cross-linked and the other part is non-cross-linked, the non-cross-linked organic material includes a non-cross-linked thermoplastic resin and a non-cross-linked elastomer or raw rubber. It is preferable to contain at least one selected from the group consisting of non-crosslinked olefin resin, non-crosslinked styrene resin, non-crosslinked diene elastomer, non-crosslinked styrene elastomer, non-crosslinked conjugated diene rubber, and non-crosslinked It is more preferable to contain at least one selected from the group consisting of butyl rubber, non-crosslinked polystyrene, non-crosslinked 1,2-polybutadiene, non-crosslinked SBS, non-crosslinked SEBS, non-crosslinked styrene-butadiene rubber, non-crosslinked At least one selected from cross-linked styrene-isoprene rubber and non-cross-linked acrylonitrile-butadiene rubber. More preferably contains, non-crosslinked polystyrene, non-crosslinked 1,2-polybutadiene, it is particularly preferred to contain at least one selected from among non-crosslinked SBS and uncrosslinked SEBS.

When a part of the organic material is cross-linked and the other part is non-cross-linked, the ratio of the cross-linked organic material in the water-insoluble member is 30% by mass or more. Is more preferable, it is more preferable that it is 50 mass% or more, and it is especially preferable that it is 70 mass% or more.
When the organic material is partially or wholly crosslinked, the crosslinking method is not particularly limited, and for example, a chemical crosslinking method, a radiation crosslinking method, a photocrosslinking method, or the like can be used. The chemical crosslinking method can be performed using, for example, an organic peroxide, sulfur, a sulfur compound, or the like as a crosslinking agent. The radiation crosslinking method can be performed by a method such as electron beam irradiation. The photocrosslinking method can be performed by a method such as ultraviolet irradiation.
Among these, it is preferable to use a chemical crosslinking method, and it is more preferable to use an organic peroxide because it has good handling properties and does not contaminate an object to be polished in the chemical mechanical polishing step. Examples of the organic peroxide include dicumyl peroxide, diethyl peroxide, di-t-butyl peroxide, diacetyl peroxide, and diacyl peroxide.

When the crosslinking is performed by chemical crosslinking, the amount of the crosslinking agent used is preferably 0.01 to 0.6 parts by mass with respect to 100 parts by mass of the water-insoluble member subjected to the crosslinking reaction. By setting the amount used within this range, it is possible to obtain a chemical mechanical polishing pad in which the generation of scratches is suppressed in the chemical mechanical polishing step.
The cross-linking may be performed collectively for all the materials constituting the water-insoluble member, or may be mixed with the remainder after performing cross-linking on a part of the material constituting the water-insoluble member. Moreover, you may mix several types of crosslinked material which performed each bridge | crosslinking.
Further, when the cross-linking is based on a chemical cross-linking method, the amount of cross-linking agent used and the cross-linking conditions are adjusted. By the operation, it is possible to easily obtain an organic material partly cross-linked and other part non-cross-linked.
The (A) water-insoluble member contains an appropriate compatibilizing agent in order to control the affinity with the water-soluble particles (B) described later and the dispersibility of the (B) water-soluble particles in the water-insoluble member. be able to. Examples of the compatibilizer include nonionic surfactants and coupling agents.

(B) Water-soluble particles (B) The water-soluble particles are detached from the water-insoluble member by contact with the chemical mechanical polishing aqueous dispersion in the chemical mechanical polishing pad and form pores in the water-insoluble member. In addition, it has the effect of increasing the indentation hardness of the polishing substrate of the chemical mechanical polishing pad, and realizes the Shore D hardness of the polishing substrate described above.
The desorption is caused by dissolution, swelling, or the like due to contact with water or an aqueous mixed medium contained in the chemical mechanical polishing aqueous dispersion.

(B) The water-soluble particles are preferably solid in order to ensure the indentation hardness of the polishing substrate of the chemical mechanical polishing pad described above. Therefore, it is particularly preferable that the water-soluble particles are solid bodies that can ensure sufficient indentation hardness in the chemical mechanical polishing pad.
(B) Although the material which comprises water-soluble particle | grains is not specifically limited, Organic water-soluble particle | grains and inorganic water-soluble particle | grains can be used. Examples of the organic water-soluble particles include sugars (polysaccharides (eg, starch, dextrin, cyclodextrin, etc.), lactose, mannitol, etc.), celluloses (hydroxypropylcellulose, methylcellulose, etc.), proteins, polyvinyl alcohol, polyvinylpyrrolidone, Examples thereof include polyacrylic acid, polyethylene oxide, water-soluble photosensitive resin, sulfonated polyisoprene, and sulfonated polyisoprene copolymer. Examples of the inorganic water-soluble particles include potassium acetate, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium chloride, potassium bromide, potassium phosphate, and magnesium nitrate. Among these, organic water-soluble particles are preferable, polysaccharides are more preferable, cyclodextrins are further preferable, and β-cyclodextrin is particularly preferable.
These water-soluble particles may be used alone or in combination of two or more. Furthermore, it may be one type of water-soluble particles made of a predetermined material, or a combination of two or more types of water-soluble particles made of different materials.

(B) The average particle diameter of the water-soluble particles is preferably 0.1 to 500 μm, more preferably 0.5 to 100 μm. By using (B) water-soluble particles having a particle size in this range, the size of the pores generated by (B) desorption of the water-soluble particles can be controlled within an appropriate range. It is possible to obtain a chemical mechanical polishing pad that is excellent in the retention capacity and polishing rate of the chemical mechanical polishing aqueous dispersion and has excellent mechanical strength.
The content of (B) water-soluble particles is preferably 1 to 90% by volume, more preferably 1 to 60% by volume, based on the total of (A) water-insoluble member and (B) water-soluble particles. More preferably, it is 3 to 40% by volume. (B) By making content of water-soluble particle into this range, the chemical mechanical polishing pad excellent in the balance of mechanical strength and polishing rate can be obtained.

The water-soluble particles (B) are dissolved or swollen in water only when exposed to the surface layer in contact with the chemical mechanical polishing aqueous dispersion in the chemical mechanical polishing pad, and do not absorb moisture inside the polishing substrate. It is preferable. For this reason, (B) water-soluble particle | grains may be provided with the outer shell which suppresses moisture absorption in at least one part of the outermost part. The outer shell may be physically adsorbed on the water-soluble particles, chemically bonded to the water-soluble particles, or may be attached to the water-soluble particles by both. Examples of the material for forming such an outer shell include epoxy resin, polyimide, polyamide, polysilicate, and the like.
(II) A material comprising a water-insoluble member and pores dispersed in the water-insoluble member The chemical mechanical polishing pad of the present invention has a water-insoluble member and pores dispersed in the water-insoluble member. Examples of the case made of the above include foams such as polyurethane, melamine resin, polyester, polysulfone, and polyvinyl acetate.
The average diameter of the pores dispersed in the water-insoluble member as described above is preferably 0.1 to 500 μm, more preferably 0.5 to 100 μm.

The shape of the polishing substrate of the chemical mechanical polishing pad of the present invention is not particularly limited, and can be, for example, a disk shape, a polygonal column shape, etc., as appropriate depending on the polishing apparatus to which the chemical mechanical polishing pad of the present invention is attached and used. You can choose.
The size of the polishing substrate is not particularly limited. For example, in the case of a disc-shaped chemical mechanical polishing pad, the diameter is 150 to 1200 mm, particularly 500 to 800 mm, the thickness is 1.0 to 5.0 mm, and particularly the thickness is 1.5 to 3. It can be 0 mm.

The polishing substrate of the chemical mechanical polishing pad of the present invention can have a groove on the polishing surface. This groove holds an aqueous dispersion for chemical machinery supplied during chemical mechanical polishing, distributes it uniformly on the polishing surface, and temporarily disposes wastes such as polishing waste and used aqueous dispersion. It has a function to be a path for staying and discharging outside.
The shape of the groove is not particularly limited, and may be, for example, a spiral shape, a concentric circle shape, a radial shape, or the like.
Further, the polishing substrate of the chemical mechanical polishing pad of the present invention may have a recess on the non-polished surface (back surface). This recess is a local excessive stress that may occur during chemical mechanical polishing. And has a function of more effectively suppressing the occurrence of surface defects such as scratches on the polished surface.

The shape of the concave portion is not particularly limited, but may be, for example, a circular shape, a polygonal shape, a spiral shape, a concentric circular shape, a radial shape, or the like.
In addition, the chemical mechanical polishing pad of the present invention can include a portion having other functions in addition to the polishing portion. Examples of the part having other functions include a window part for detecting an end point using an optical end point detection device. As the window part, for example, at a thickness of 2 mm, the transmittance of light of any wavelength between 100 and 300 nm is preferably 0.1% or more, more preferably 2% or more, or A material having an accumulated transmittance in any wavelength region between wavelengths of 100 to 300 nm is preferably 0.1% or more, more preferably 2% or more. The material of the window portion is not particularly limited as long as it satisfies the optical characteristics described above. For example, the same composition as that of the above-described polishing substrate can be used.

  The manufacturing method of the polishing substrate constituting the chemical mechanical polishing pad of the present invention is not particularly limited, and the polishing substrate may optionally have a groove or a recess (hereinafter referred to as “groove or the like” together). .) Is not particularly limited. For example, a chemical mechanical polishing pad composition to be a polishing base of a chemical mechanical polishing pad is prepared in advance, and after this composition is molded into a desired shape, grooves and the like can be formed by cutting. Further, by molding a chemical mechanical polishing pad composition using a mold in which a pattern to be a groove or the like is formed, the groove or the like can be formed simultaneously with the rough shape of the polishing substrate.

  The method for obtaining the chemical mechanical polishing pad composition is not particularly limited. For example, necessary materials such as predetermined organic materials can be obtained by kneading with a kneader or the like. A conventionally known kneader can be used. Examples thereof include kneaders such as rolls, kneaders, Banbury mixers, and extruders (single screw and multi screw).

The polishing pad composition containing water-soluble particles for obtaining a polishing pad containing water-soluble particles can be obtained, for example, by kneading a water-insoluble matrix, water-soluble particles and other additives. However, it is usually kneaded by heating so that it is easy to process during kneading, but the water-soluble particles are preferably solid at this temperature. By being solid, water-soluble particles can be dispersed at the above-mentioned preferable average particle diameter regardless of the compatibility with the water-insoluble matrix. Therefore, it is preferable to select the type of water-soluble particles according to the processing temperature of the water-insoluble matrix used.
The chemical mechanical polishing pad of the present invention may be composed only of the above-mentioned polishing substrate, or may be a multilayer pad provided with a support layer on the non-polishing surface side of the above-mentioned polishing substrate. .

  The support layer is a layer that supports the polishing substrate on the back side of the polishing surface. The characteristics of the support layer are not particularly limited, but are preferably softer than the polishing substrate. By providing a softer support layer, when the thickness of the polishing substrate is thin, for example, even when the thickness is 1.0 mm or less, it is possible to prevent the polishing substrate from floating during polishing and the surface of the polishing layer from being curved. Polishing can be performed stably. The hardness of the support layer is preferably 90% or less of the hardness of the polishing substrate, more preferably 50 to 90%, particularly preferably 50 to 80%, and particularly preferably 50 to 70%.

The support layer may be a porous body (foam) or a non-porous body. Furthermore, the planar shape is not particularly limited, and may be the same as or different from the polishing layer. The planar shape of the support layer can be, for example, a circle or a polygon (such as a quadrangle). Moreover, although the thickness is not specifically limited, for example, 0.1-5 mm is preferable, More preferably, it can be 0.5-2 mm.
The material constituting the support layer is not particularly limited, but it is preferable to use an organic material because it can be easily molded into a predetermined shape and properties and can be provided with appropriate elasticity.
The chemical mechanical polishing pad of the present invention as described above can suppress the generation of scratches on the surface to be polished and provide a high-quality surface to be polished.

The chemical mechanical polishing pad of the present invention can be mounted on a commercially available polishing apparatus and used in the chemical mechanical polishing step by a known method.
The chemical mechanical polishing pad of the present invention can be used in a wide range of chemical mechanical polishing processes for manufacturing semiconductor devices.
Examples of the polishing object that can be subjected to chemical mechanical polishing using the chemical mechanical polishing pad of the present invention include a metal as a wiring material, a barrier metal, and an insulating film. Examples of the metal include tungsten, aluminum, copper, and alloys containing these. Examples of the barrier metal include tantalum, tantalum nitride, titanium, titanium nitride, and tungsten nitride. As the insulating film, a silicon oxide film (PETOS film (Plasma Enhanced-TEOS film), HDP film (High Density Plasma Enhanced-TEOS film)) formed by a vacuum process such as chemical vapor deposition, or an oxide obtained by a thermal CVD method is used. silicon film, etc.), a small amount of boron and phosphorus added boron phosphorus silicate film (BPSG film SiO _2), FSG fluorine-doped _{SiO 2 (fluorine-doped silicate glass} ) and an insulating film called, SiON (silicon oxynitride) And an insulating film called silicon nitride, a low dielectric constant insulating film, and the like.

As the low dielectric constant insulating film, for example, in the presence of oxygen, carbon monoxide, carbon dioxide, nitrogen, argon, H ₂ O, ozone, ammonia, alkoxysilane, silane, alkylsilane, arylsilane, siloxane, Insulating film made of polymer obtained by plasma polymerization of silicon-containing compounds such as alkylsiloxane, insulating film made of polysiloxane, polysilazane, polyarylene ether, polybenzoxazole, polyimide, silsesquioxane, etc., low dielectric constant The silicon oxide insulating film can be mentioned.

As described above, the chemical mechanical polishing pad of the present invention can be used for a wide range of chemical mechanical polishing processes, and can be particularly preferably used for a damascene wiring forming process using copper as a wiring material. The process of forming damascene wiring using copper as the wiring material consists of depositing copper as the wiring material after forming the barrier metal layer in the groove portion of the insulating film in which the groove is to be formed in the portion to be the wiring and in the portion other than the groove portion And removing the excess copper (first polishing process), removing the barrier metal outside the groove part (second polishing process), and slightly polishing the insulating film portion (third) A flat damascene wiring is obtained through a polishing process. The chemical mechanical polishing pad of the present invention can also be used in a chemical mechanical polishing step for use in any of the first to third polishing treatment steps.
In addition, it should be understood that the above “copper” is an alloy of copper and aluminum, silicon, or the like other than pure copper, and includes a copper content of 95% by mass or more. .

Example 1
(1) Manufacture of chemical mechanical polishing pad (1-1) Preparation of composition for chemical mechanical polishing pad 1,2-polybutadiene (manufactured by JSR Corporation, trade name “JSR RB830”) 72.2 parts by mass and β- 27.2 parts by mass of cyclodextrin (trade name “Dexy Pearl β-100”, average particle size 20 μm, manufactured by Yokohama International Bio-Laboratory Co., Ltd.) was kneaded for 2 minutes with a router adjusted to 160 ° C. Subsequently, 0.45 parts by mass of “Park Mill D40” (trade name, manufactured by NOF Corporation, containing 40% by mass of dicumyl peroxide) (dicumyl peroxide per 100 parts by mass of 1,2-polybutadiene) In addition, it corresponds to 0.25 parts by mass.) In addition, the mixture was further kneaded at 120 ° C. and 60 rpm for 2 minutes to obtain pellets of the chemical mechanical polishing pad composition.

(1-2) Measurement of Storage Elastic Modulus of Polishing Substrate This pellet was heated in a mold at 170 ° C. for 18 minutes and crosslinked to obtain a disk-shaped molded body having a diameter of 600 mm and a thickness of 2.5 mm. It was. This is cut into strips of 2.5 mm in width, 30 mm in length, and 1.0 mm in thickness with a translational cutting device (model SDL-200STT) manufactured by Dumbbell Co., Ltd., and this is used as a test piece to measure the viscoelasticity. (Rheometric Scientific, type “RSAIII”), storage elasticity in tensile mode at 30 ° C. and 60 ° C. under initial load of 100 g, maximum strain of 0.01%, frequency of 0.2 Hz. The rate was measured. Its storage elastic modulus at 30 ° C. was 89 MPa, 60 ° C. was 23 MPa, and the ratio was 3.9.

(1-3) Preparation of window member 97 parts by mass of 1,2-polybutadiene (manufactured by JSR Corporation, trade name “JSR RB830”) and β-cyclodextrin (manufactured by Yokohama International Bio-Laboratory Co., Ltd., commodity) 3 parts by mass (namely “Dexy Pearl β-100”, average particle size 20 μm) was kneaded for 2 minutes with a rudder adjusted to 160 ° C. Next, 1.19 parts by weight (dicumyl peroxide per 100 parts by weight of 1,2-polybutadiene) of “Park Mill D40” (trade name, manufactured by NOF Corporation, containing 40% by weight of dicumyl peroxide). In addition, this corresponds to 0.5 parts by mass.) In addition, the mixture was further kneaded at 120 ° C. and 60 rpm for 2 minutes to obtain a chemical mechanical polishing pad composition pellet. The pellet was heated in a mold at 170 ° C. for 18 minutes and crosslinked to obtain a disk-shaped molded body having a diameter of 600 mm and a thickness of 2.4 mm. Further, a dumbbell punching machine (model SDL-200) manufactured by Dumbbell Co., Ltd. was used to obtain a punching window member having a width of 20 mm, a length of 58 mm, and a thickness of 2.4 mm. The transmittance of this member at a wavelength of 670 nm was measured using a UV absorbance meter (manufactured by Hitachi, Ltd., model U-2010), and the transmittance was 40%.

(1-4) Production of Chemical Mechanical Polishing Pad A disk-shaped molded body having a diameter of 600 mm and a thickness of 2.5 mm was obtained in the same manner as in (1-2) above. Next, using a commercially available cutting machine, concentric grooves having a width of 0.5 mm, a pitch of 2.0 mm, and a depth of 1.0 mm on the polished surface side of the molded body (the cross-sectional shape is rectangular). ) Was formed. Further, a through hole having a width of 21 mm and a length of 59 mm was formed at a position 72 mm from the center of the molded body. A double-sided tape (manufactured by Sekisui Chemical Co., Ltd., product name “Double Tack Tape # 512”) is pasted on the entire surface where the groove was not formed, and the window portion prepared in (1-3) is placed in the through hole. The member was inserted. Further, a chemical mechanical polishing pad was obtained by cutting into a diameter of 508 mm along the concentric grooves.

(2) Evaluation of chemical mechanical polishing performance (2-1) Example of polishing a wafer having a pattern made of copper and a low dielectric constant insulating film The chemical mechanical polishing pad manufactured as described in (1) above is optical Mounted on a surface plate of a chemical mechanical polishing apparatus “Mirra / Mesa” (Applied Materials) with an end point detector, Semitech 800BDM001 (trade name, manufactured by International SEMATECH) A silicon carbide layer is formed on the silicon substrate, A layer of an insulating film Black Diamond (trade name, manufactured by Applied Materials) of a low dielectric constant is formed in a portion other than a portion to be a wiring, and further, tantalum as a barrier metal and copper as a wiring material are further formed in this order. Test wafer deposited in step 1). To, and chemical mechanical polishing in two stages under the following conditions.
The polishing time of the first stage polishing is monitored by the laser-light reflectivity using an optical end point detector of the chemical mechanical polishing apparatus, and when the reflectivity changes completely from the start of polishing (that is, the barrier metal is exposed). The time taken up to (time) was set to 1.2 times. The first stage polishing time of this example set in this way was 150 seconds.

Conditions for the first stage polishing Chemical mechanical polishing aqueous dispersion: iCue5003 (trade name, manufactured by Cabot Microelectronics, Inc. containing silica as abrasive grains) and 30% by mass hydrogen peroxide solution at a volume ratio of 11: 1 Mixed one.
Aqueous dispersion supply amount: 300 mL / min Plate rotation speed: 120 rpm
Head rotation speed: 108 rpm
Head pressing pressure Retainer ring pressure: 5.5 psi
Membrane pressure: 4.0 psi
Inner tube pressure: 3.0 psi

Conditions for the second stage polishing Chemical mechanical polishing aqueous dispersion: CMS-8301 (trade name, manufactured by JSR Co., Ltd.) added with 1% by mass of 30% by mass hydrogen peroxide.
Aqueous dispersion supply amount: 200 mL / min Plate rotation speed: 60 rpm
Head rotation speed: 54 rpm
Head pressing pressure Retainer ring pressure: 5.5 psi
Membrane pressure: 3.0 psi
Inner tube pressure: 0.0 psi
Polishing time: 100 seconds Using the wafer defect inspection device (model “KLA2351” manufactured by KLA-Tencor, Inc.) on the entire polished surface of the wafer after polishing, the generated scratch was measured. 3 on the low dielectric constant insulating film.

Measurement conditions for KLA2351 Spectrum mode: Visible
Pixel size: 0.62 μm
Threshold: 50
Merge: 100
Size Sieve: 1 μm ²

(3) Evaluation of outer peripheral peeling of the low dielectric constant insulating film (when the low dielectric constant insulating film is the polished surface)
(3-1) Production of low dielectric constant insulating film (i) Preparation of polysiloxane sol 101.5 g of methyltrimethoxysilane, 276.8 g of methyl methoxypropionate and 9.7 g of tetraisopropoxytitanium / ethyl acetoacetate The solution consisting of the complex was heated to 60 ° C. To this solution, 112.3 g of a mixture of γ-butyrolactone and water (weight ratio 4.58: 1) was added dropwise over 1 hour. After completion of the dropwise addition of the mixture, the mixture was further reacted at 60 ° C. for 1 hour to obtain a polysiloxane sol containing 15% by mass of polysiloxane.

(Ii) Production of polystyrene particles 100 parts by mass of styrene, 2 parts by mass of an azo polymerization initiator (trade name “V60”, manufactured by Wako Pure Chemical Industries, Ltd.), 0.5 parts by mass of potassium dodecylbenzenesulfonate, and ion exchange 400 parts by mass of water was put into a flask, heated to 70 ° C. with stirring in a nitrogen gas atmosphere, and stirring was continued at this temperature for 6 hours. The reaction mixture was filtered and dried to obtain polystyrene particles having a number average particle diameter of 150 nm.

(Iii) Production of low dielectric constant insulating film 15 g of the polysiloxane sol obtained in the above (i) and 1 g of the polystyrene particles obtained in the above (ii) are mixed, and the resulting mixture is 8 inches in diameter. The film was applied on a silicon substrate with a thermal oxide film (manufactured by Asahi Sangyo Co., Ltd.) by spin coating, and heated at 80 ° C. for 5 minutes to form a coating film having a thickness of 1.39 μm. Thereafter, heating was carried out at 200 ° C. for 5 minutes, then at 340 ° C., 360 ° C. and 380 ° C. in order of 30 minutes each at a pressure of 5 torr, and further heated at 450 ° C. for 1 hour to form a colorless transparent film (film A thickness of 2,000 mm) was formed.
When the cross section of this film was observed with a scanning electron microscope, it was confirmed that fine pores were formed. The relative dielectric constant was 1.98, the elastic modulus was 3 GPa, and the porosity was 15% by volume.

(3-2) Polishing of Low Dielectric Constant Insulating Film Chemical mechanical polishing was performed under the following conditions using the low dielectric constant insulating film produced as described above as the surface to be polished. Note that the following polishing test is an accelerated test under conditions where the insulating film having a low dielectric constant is easily peeled off.

Chemical mechanical polishing equipment: Mirra / Mesa (manufactured by Applied Materials)
Chemical mechanical polishing aqueous dispersion type: CMS-8301 (trade name, manufactured by JSR Corporation, containing colloidal silica as abrasive grains)
Chemical mechanical polishing aqueous dispersion supply rate: 100 mL / min
Plate rotation speed: 60rpm
Head rotation speed: 54 rpm
Head pressing pressure Retainer ring pressure: 6.5 psi
Membrane pressure: 5.0 psi
Inner tube pressure: 0 psi
Polishing time: 15 seconds

About the to-be-polished surface after grinding | polishing, the presence or absence of peeling in the low dielectric constant insulating film outer peripheral part was observed using the optical microscope.
When peeling of the low dielectric constant insulating film occurs, the maximum value of the distance at which peeling from the outer periphery of the insulating film occurs is shown in Table 3. When the maximum value is 0, it indicates that no peeling occurred.

(4) Evaluation of peeling of the outer periphery of the low dielectric constant insulating film (when the metal film is the surface to be polished and the low dielectric constant insulating film is the lower layer)
(4-1) Evaluation of chemical mechanical polishing performance ATDF800LKD003 (trade name, manufactured by ATDF. A silicon carbide layer is formed on a silicon substrate, and a low dielectric constant insulating film LKD5109 is formed on a portion other than the portion to be a wiring on the silicon substrate. (Trade name, manufactured by JSR Co., Ltd.), and a test wafer in which tantalum as a barrier metal and copper as a wiring material are further deposited in this order.) Chemical mechanical polishing was performed under the following conditions. Note that the following polishing test is an accelerated test under conditions where the insulating film having a low dielectric constant is easily peeled off.

Chemical mechanical polishing equipment: Mirra / Mesa (manufactured by Applied Materials)
Aqueous dispersion for chemical mechanical polishing: A mixture of iCue5003 (trade name, manufactured by Cabot Microelectronics, Inc. containing silica as abrasive grains) and 30% by mass hydrogen peroxide water at a volume ratio of 11: 1.
Aqueous dispersion supply amount: 100 mL / min Plate rotation speed: 120 rpm
Head rotation speed: 108 rpm
Head pressing pressure Retainer ring pressure: 6.5 psi
Membrane pressure: 5.0 psi
Inner tube pressure: 4.0 psi
Polishing time: 15 seconds

With respect to the polished surface after polishing, the presence or absence of peeling at the outer peripheral portion of the lower low dielectric constant insulating film was observed using an optical microscope.
Table 3 shows the maximum value of the distance at which peeling from the outer periphery of the insulating film occurs when the low dielectric constant insulating film is peeled off or peeled off.

Examples 2-10
In Example 1, it carried out like Example 1 except having made the kind and usage-amount of each raw material in "(1-1) Preparation of the composition for chemical mechanical polishing pads" as Table 1. FIG. The evaluation results are shown in Tables 2 and 3.
However, the abbreviations used in Table 1 represent the following, respectively. Moreover, the numerical value in Table 1 is a mass part.
RB830: 1,2-polybutadiene (manufactured by JSR Corporation, trade name “JSR RB830”)
RB810: 1,2-polybutadiene (manufactured by JSR Corporation, trade name “JSR RB810”)
TR2827: Styrene-butadiene block copolymer (manufactured by JSR Kraton Elastomer Co., Ltd., trade name “TR2827”)
HF55: Polystyrene (manufactured by PS Japan Ltd., trade name “HF55”)
β-CD: β-cyclodextrin (manufactured by Yokohama International Bio-Institute, trade name “Dexy Pearl β-40”, average particle size 20 μm)
D40: Nippon Oil & Fat Co., Ltd., trade name “Park Mill D40”, containing 40% by mass of dicumyl peroxide.
PHR: The amount of organic peroxide per 100 parts by mass of the raw material of the water-insoluble member (the mass is converted to a pure organic peroxide).

Comparative Example 1
Chemical mechanical polishing was performed and evaluated in the same manner as in Example 1 except that the product name “IC1000” manufactured by Rodel Nitta Co., Ltd. was used as the chemical mechanical polishing pad. The results are shown in Tables 2 and 3. Since “IC1000” does not have a window for allowing the detection light of the optical end point detector to pass through, and the optical end point detector cannot be used, the time for the first stage polishing is 150 seconds according to Example 1. did.

Claims (4)

Following conditions initial load: 100g
Maximum strain: 0.01%
Frequency: 0.2Hz
When the storage elastic modulus at 30 ° C. and 60 ° C. of the polishing substrate was measured, the storage elastic modulus E ′ (30 ° C.) at 30 ° C. was 120 MPa or less, and the storage elastic modulus E ′ (30 ° C.) at 30 ° C. And a storage elastic modulus E ′ (60 ° C.) ratio at 60 ° C. (E ′ (30 ° C.) / E ′ (60 ° C.)) of 2.5 or more. The polishing substrate comprises a water-insoluble member and water-soluble particles dispersed in the water-insoluble member. The water-insoluble member is crosslinked with 100 parts by mass of an organic material and 0.01 to 0.6 parts by mass of a crosslinking agent. A chemical mechanical polishing pad according to claim 1, consisting of a crosslinked and cross-linked organic material or of a cross-linked organic material. A chemical mechanical polishing method comprising performing a chemical mechanical polishing step using the chemical mechanical polishing pad according to claim 1. The chemical mechanical polishing method according to claim 3, wherein the chemical mechanical polishing step is a step of forming damascene wiring using copper as a wiring material.