JP2008098525A - Polishing composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing composition which has high polishing selectivity keeping an industrially useful polishing speed; and to provide a polishing composition which is preferably used in a CMP process inhibiting the occurrence of erosion even if making an overpolish particularly in a process for manufacturing a semiconductor device. <P>SOLUTION: A polishing composition, which contains a resin emulsion including a water soluble resin (A) with an amide group, has a high polishing speed and a high polishing selectivity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polishing composition in the field of electronic information materials and a method for producing an electronic information material member using the composition.

  In recent years, in a wiring forming process, which is a process for manufacturing a semiconductor device, a groove for forming a wiring is dug on an insulating film formed on a semiconductor wafer, and a metal film for wiring is plated so as to cover the groove. A technique for embedding using a method or the like and forming a metal wiring by removing an excessive metal film is used. Here, a polishing method called CMP (Chemical and Mechanical Polishing) is used to remove the excessive metal film and planarize the surface of the semiconductor wafer. CMP is not a mechanical polishing using mere abrasive grains, but a method of mechanically polishing the surface to be polished that has been modified by applying a chemical action, and the cooperation between the chemical action and the mechanical action. Therefore, a controlled integration of chemical and mechanical action is important.

  Conventionally, inorganic abrasive grains such as ceria, alumina, and silica have been used as abrasive grains for CMP. However, these inorganic abrasive grains have high hardness, and problems such as scratching, dishing, and erosion have not been solved when a metal having low hardness such as copper is used as a metal for wiring formation.

Scratches are caused when the abrasive grains are too hard with respect to the material to be polished or the abrasive grains aggregate to locally overpolish the surface to be polished, and there is a problem of breaking the wiring of the semiconductor device.
The dishing may be caused by distortion of the polishing pad during polishing, or the type and amount of the pH adjusting agent or complex forming agent for adjusting the liquid property of the metal polishing composition and compatibility with the surface to be polished. Poorly occurs when the chemical properties of the surface to be polished are mismatched with the mechanical polishing characteristics. The form is a concave shape that is generated when the metal film of the wiring portion is polished more excessively than the surroundings at the center of the wiring.
Erosion is a generation of a concave shape larger than dishing that occurs in densely packed wiring patterns, and is a barrier film that prevents excessive polishing due to excessively hard abrasive grains and diffusion of metal films, insulating films, and metals for wiring This is caused by low polishing selectivity for each object to be polished on a non-uniform polished surface made of, for example. The conventional slurry containing inorganic abrasive grains has a strong mechanical effect and is easy to obtain a high polishing rate. However, excessive polishing of the insulating film layer and the barrier layer proceeds in the wiring region where the wiring density is high and the strength is weak, and erosion occurs. Is likely to occur. In general, in order to completely remove the metal film other than the metal wiring part on the entire surface of the substrate to be polished, the polishing time is set according to the slowest part of the polishing rate. Under such conditions, the polishing rate is high. In the region, excessive polishing (over polishing) proceeds, and erosion tends to increase.
Dishing and erosion cause an increase and variation in wiring resistance, and further cause a short circuit between wiring layers formed in an upper layer.
When scratch, dishing, and erosion occur in this way, the reliability of the semiconductor device is significantly reduced, and the manufacturing yield is greatly reduced.

  In particular, in order to improve the performance of semiconductor devices, the 1/2 wiring width on the insulating film has been reduced from 90 nm to 65 nm, and further to 45 nm, and problems such as scratching, dishing, and erosion have become more serious. There is a need for a polishing composition that minimizes damage to the surface to be polished while ensuring a polishing rate within a practical range. In particular, when the wiring width is 45 nm or more, the thickness of the barrier layer is further reduced, so that the occurrence of erosion is expected to become more serious.

  In order to solve these problems, a polishing composition has been developed in which the inorganic abrasive grains are made of silica softer than alumina, and the metal to be polished forms a passive state and the metal ions are not easily eluted, so that polishing is performed from the neutral to the alkaline side. ing. However, even if the inorganic abrasive grains are changed from alumina to silica, the generation of scratches due to the abrasive grains themselves is suppressed, but it has been possible to solve the occurrence of scratches and erosion due to the aggregates of abrasive grains and the shavings of the metal to be polished. Absent.

  On the other hand, in Japanese Patent No. 3172008 (Patent Document 1), a polishing method using particles made of an organic polymer compound or particles mainly composed of carbon selected from the group consisting of amorphous carbon and carbon black as abrasive particles. Is disclosed. However, the problem is to completely remove the abrasive grains remaining on the surface to be polished after polishing, and the specifically disclosed organic polymer compounds are methacrylic resins and polystyrene resins having no functional groups, and Since an oxidizing agent that oxidizes the surface of the polishing metal is not added, the chemical action with the metal to be polished does not work at all, and as a result, an industrially meaningful polishing rate is not obtained.

  Japanese Patent Application Laid-Open No. 2001-55559 (Patent Document 2) discloses an aqueous dispersion for chemical mechanical polishing containing organic particles having a functional group capable of reacting with a surface to be polished. Although improved, there has been no evaluation of dishing or erosion.

  Japanese Patent Application Publication No. 2004-532521 (Patent Document 3) discloses a CMP polishing composition containing a water-soluble carboxylic acid polymer, but polishing is performed on the acid side in the case of a metal corrosion region, that is, copper. For this reason, there is a problem that a slit-shaped depression called a fang is easily formed when a copper corrosion reaction proceeds at the interface portion between the copper layer and the barrier metal layer and copper ions are eluted.

  Japanese Patent No. 3337464 (Patent Document 4) discloses a metal polishing liquid containing two different types of protective film forming agents. Specifically, benzotriazoles are disclosed as the first protective film forming agent, and water-soluble polymers such as polyacrylic acid and polymethacrylic acid are disclosed as the second protective film forming agent. The effect of suppressing etching is low and it cannot be expected to suppress the occurrence of dishing. Further, there is a risk that the viscosity increases due to neutralization and the fluidity of the polishing liquid decreases, thereby reducing the polishing rate and the polishing quality. Further, since it does not substantially contain abrasive grains, an industrially meaningful polishing rate cannot be obtained.

  JP 2003-313541 A (Patent Document 5) suppresses polishing of tantalum used as a barrier metal material by using resin particles having a lower elastic modulus than conventional inorganic abrasive grains, thereby polishing copper and tantalum. Although it is disclosed that the selectivity can be improved, the polishing rate of copper is slower than the conventional inorganic abrasive grains, so that a sufficient polishing selection ratio of copper and tantalum cannot be obtained, and erosion is completely prevented. It is expected to be difficult to suppress.

  In JP-A-2003-303791 (Patent Document 6) and JP-A-2003-303792 (Patent Document 7), scratches can be suppressed by using an abrasive composed of a water-soluble polymer containing an anionic functional group and fine particles. Although disclosed, it is expected that it is difficult to completely suppress the generation of erosion with inorganic abrasive grains such as silica exemplified in the examples.

Japanese Patent Laid-Open No. 2001-144049 (Patent Document 8) discloses that the generation of erosion can be suppressed by using a polishing liquid containing a water-soluble polymer. A meaningful polishing rate is not obtained.
Japanese Patent No. 3172008 JP 2001-55559 A JP-T-2004-532521 Japanese Patent No. 3337464 Japanese Patent Laid-Open No. 2003-313541 JP 2003-303791 A JP 2003-303792 A JP 2001-144049 A

A polishing composition having high polishing selectivity while maintaining an industrially useful polishing rate, particularly suitable for a CMP process that suppresses the occurrence of erosion even when overpolishing is performed in the process of manufacturing a semiconductor device. A polishing composition is provided. Furthermore, a slurry containing the composition and a method for manufacturing a semiconductor device using the slurry are also provided.

  The inventors have intensively studied to solve the above problems, and as a result, the present invention has been completed. That is, the polishing composition of the present invention includes a resin emulsion containing a water-soluble resin (A) having an amide group.

  The average particle size of the resin emulsion containing the water-soluble resin (A) having an amide group is preferably 40 to 500 nm, more preferably 40 to 400 nm, and still more preferably 50 to 300 nm. The average molecular weight of the water-soluble resin (A) is preferably 50,000 or less, more preferably 300,000 or less. From the viewpoint of obtaining a high polishing rate, the weight of the water-soluble resin (A) having an amide group is preferably 10 to 90% by weight, and more preferably 20 to the total weight of the resin component in the polishing composition. 80% by weight, more preferably 30 to 70% by weight.

Further, from the viewpoint of enhancing the dispersibility in water, the water-soluble resin (A) having an amide group is a functional group capable of forming an anion, more specifically at least among a carboxyl group, a sulfonic acid group, and a phosphoric acid group. It preferably has one further, and a carboxyl group is particularly preferred.
Further, from the viewpoint of reducing dishing, the functional group capable of forming an anion with respect to the total weight of the resin component in the polishing composition (more preferably at least one of a carboxyl group, a sulfonic acid group, and a phosphoric acid group). The weight of the resin derived from the monomer having a carboxyl group is more preferably 0.1 to 40% by weight, and more preferably 1 to 30% by weight.

  Further, an oxidizing agent (preferably hydrogen peroxide), a water-soluble compound capable of forming a complex with the metal to be polished (preferably carboxylic acid and other organic acids, amines, amino acids, ammonia), an anticorrosive agent (preferably Is preferably a benzotriazole derivative and / or an aromatic compound having a carboxyl group), from the viewpoint of suppressing a high polishing rate and dishing. As a more preferable embodiment, an oxidizing agent and an organic compound are included. Each of them contains at least one acid, and still more preferably contains at least one anticorrosive.

In particular, when used as a slurry in the process of manufacturing a semiconductor device, in order to improve the uniformity of the polishing rate within the wafer surface and to suppress clogging of the slurry in the slurry supply line, addition that further suppresses foaming An agent (preferably a polyethylene glycol type nonionic surfactant, an emulsion of a fatty acid ester, a polyether nonionic surfactant) may be contained. A particularly preferred embodiment in such applications includes those containing at least one antifoaming agent in addition to the oxidizing agent, organic acids and anticorrosive agent.

The polishing composition of the present invention has a high polishing rate and a high polishing selectivity. In particular, in the process of manufacturing a semiconductor device, generation of erosion can be suppressed even if overpolishing is performed.

  A polishing composition containing a resin emulsion containing a water-soluble resin (A) having an amide group, a slurry containing the composition, and a method for producing a semiconductor device using the slurry will be specifically described.

The polishing composition containing the resin emulsion containing the water-soluble resin (A) having an amide group has a high polishing rate and a high polishing selectivity. More specifically, in the case of polishing a pattern of alternately forming a metal embedded wiring with a width of 9.0 μm and an insulating film with a width of 1.0 μm shown in FIG. When the metal film (L1) having a thickness of 0.1 to 30 μm is polished for 1.5 times the time necessary for polishing until the lower layer (L2) is exposed under certain polishing conditions. The amount of dent (erosion amount) in the lower layer (L2) that is generated can be suppressed to preferably 10 nm or less, more preferably 8 nm or less.
When the metal film (L1) contains at least one selected from copper, copper alloys, and oxides thereof, a greater effect can be seen. Further, when the lower layer (L2) contains at least one selected from tantalum, tantalum nitride, tantalum alloy, titanium, titanium nitride, titanium alloy, ruthenium, and ruthenium alloy, more preferably tantalum, a greater effect is obtained. It can be seen.

(Water-soluble resin (A))
The polishing composition can obtain a high polishing rate by including a water-soluble resin containing an amide group. The water-soluble resin has a water solubility at which the transmittance of an aqueous solution having a resin content of 10% by weight (wavelength 400 nm, for example, using a UV / VIS / IR spectrometer JASCO V-570) is 85% or more. High resin.
The monomer constituting the water-soluble resin (A) is 10 to 99% by weight, preferably 50 to 99% by weight, more preferably 70 to 99% by weight based on the total amount of the water-soluble resin (A). % Of the monomer preferably has an amide group.

  Examples of monomers having an amide group include (meth) acrylamide, N-vinylacetamide, N-alkyl (meth) acrylamide, N, N'-dialkyl (meth) acrylamide, hydroxyalkyl (meth) acrylamide, and N-isopropylacrylamide. And methylenebis (meth) acrylamide, aminoethyl (meth) acrylate, and diethylaminoethyl (meth) acrylate. In particular, (meth) acrylamide is particularly preferable from the viewpoint of obtaining a high polishing rate.

  In addition to the amide group, the water-soluble resin preferably further has a functional group capable of forming an anion from the viewpoint of dispersion stability of the resin emulsion. Examples of the functional group capable of forming an anion include a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and a carboxyl group is preferable.

  From the viewpoint of obtaining a high polishing rate, the weight of the water-soluble resin (A) having an amide group is preferably 10 to 90% by weight, more preferably 15%, based on the total weight of the resin components in the polishing composition. -80% by weight, more preferably 20-70% by weight.

  The total weight of the resin component in the composition and the content of the water-soluble resin (A) are, for example, 1 for solid content of the resin emulsion and the emulsion using an ultracentrifuge (himacCS100FX; manufactured by HITACHI) at 85000 rpm and 20 ° C. After time centrifugation, the supernatant solids are separated from the water-soluble resin (A) and the additive components (additive components are extracted from the supernatant solids and the remainder is regarded as the water-soluble resin (A)), and the solids after centrifugation Can be regarded as a resin component other than the water-soluble resin (A). Further, the average molecular weight of the water-soluble resin (A) is preferably 500,000 or less from the viewpoint of obtaining high solubility in water, and more preferably 300,000 or less.

(Method for producing water-soluble resin (A))
The method for synthesizing the water-soluble water-soluble resin (A) having an amide group is not particularly limited, but polymerization performed in a solvent containing water as a main component is preferable. A particularly preferred polymerization form is aqueous solution polymerization.
Hereinafter, the manufacturing method of water-soluble resin by aqueous solution (co) polymerization is explained in full detail.

For example, add distilled water to a flask equipped with a stirrer and a reflux condenser, replace with inert gas, add a polymerization initiator, and gradually add an aqueous solution containing a mixture of vinyl monomers while stirring. Can be obtained by completing.
Although there is no restriction | limiting in a polymerization initiator, A water-soluble radical initiator is preferable and water-soluble azo initiators, such as persulfates, such as ammonium persulfate, and 4,4'-azobis (4-cyanovaleric acid), are especially preferable. .
The polymerization temperature is not particularly limited, but it is preferably synthesized in the range of 30 to 95 ° C. in consideration of the production time and the conversion rate of the monomer to the copolymer (reaction rate). ° C is particularly preferred. Further, for the purpose of improving the production stability, it is also possible to use a pH adjusting agent, EDTA which is a metal ion sealing agent, or a salt thereof.

  Monomers having an amide group used for (co) polymerization include (meth) acrylamide, N-vinylacetamide, N-alkyl (meth) acrylamide, N, N′-dialkyl (meth) acrylamide, hydroxyalkyl (meth) ) Acrylamide, N-isopropylacrylamide and the like, preferably (meth) acrylamide, more preferably methacrylamide. Two or more monomers having an amide group may be used. When the water-soluble resin (A) having an amide group is synthesized by (co) polymerization, the water-soluble resin (A) may be synthesized from only one or more monomers having an amide group, or may be synthesized from one or more monomers having an amide group. It may be produced by copolymerization of a monomer and another monomer having no amide group.

Other monomers having no amide group include hydrophobic vinyl monomers such as styrene, alkyl (meth) acrylate, isobornyl (meth) acrylate and cyclohexyl (meth) acrylate, and cyano such as (meth) acrylonitrile. Group-containing vinyl monomers, carboxyl group-containing vinyl monomers such as (meth) acrylic acid, hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl (meth) acrylate, and glycidyl group-containing vinyl such as glycidyl (meth) acrylate Monomers, amino group-containing vinyl monomers such as N, N-dimethylaminoethyl (meth) acrylate, and acetoacetoxy group-containing vinyl monomers such as acetoacetoxyethyl (meth) acrylate. If necessary, crosslinkable vinyl monomers may be used. Examples of such crosslinkable vinyl monomers include methylenebis (meth) acrylamide, divinylbenzene, polyethylene glycol chain-containing di (meth) acrylate, etc. Can be illustrated. Further, a crosslinkable vinyl monomer containing two or more vinyl groups may be used.
A preferred embodiment of the water-soluble resin (A) having an amide group includes those having a functional group capable of forming an anion. As a method for introducing into A), a certain amount of the monomer having a functional group capable of forming an anion, preferably 0.5 to 30% by weight, more preferably, with respect to the total weight of the starting monomer A method of adding 1 to 20% by weight and copolymerizing is preferable.

  Monomers having functional groups capable of forming anions include unsaturated monobasic acids such as acrylic acid, methacrylic acid, and crotonic acid, unsaturated dibasic acids such as itaconic acid, fumaric acid, and maleic acid, and methacrylsulfonic acid. And sulfonic acid-containing monomers such as sodium styrenesulfonate, and phosphoric acid-containing monomers such as 2-methacryloxyethyl acid phosphate, and two or more of them may be used. In particular, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, allyl sulfonic acid, methallyl sulfonic acid, and 2-methacryloylethyl acid phosphate are preferable.

As a combination of (co) polymerization, (meth) acrylamide and (meth) acrylic acid are preferable, and methacrylamide and methacrylic acid are more preferable.
When polymerizing the water-soluble resin (A), if necessary, the molecular weight of mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, alcohols such as isopropanol, α-methylstyrene dimer, methallyl sulfonate, etc. You may use as a regulator.

(Resin emulsion containing water-soluble resin (A) and method for producing the same)
There is no restriction | limiting in particular in the presence form of water-soluble resin (A) in polishing composition, It has taken the form which at least one part of water-soluble resin (A) adsorb | sucked chemically or physically on the surface of the resin emulsion. May be.

  Although there is no restriction | limiting in particular in the manufacturing method of a resin emulsion, Polymerization performed in the solvent which has water as a main component is preferable. For example, by performing emulsion polymerization in an aqueous solvent containing the water-soluble resin (A), or by (co) polymerizing a monomer containing an amide group in an aqueous solvent system in which the emulsion polymerization resin particles are present, A resin emulsion containing the water-soluble resin (A) (hereinafter also referred to as a resin emulsion (B)) can be obtained. Also, the resin emulsion (B) can be obtained by mixing the water-soluble resin (A) and the resin obtained by emulsion polymerization after polymerization.

  The composition of the monomer constituting the resin emulsion (B) containing the water-soluble resin (A) is 5 to 90 wt% of monomers having an amide group with respect to the total weight of all monomers in the composition. %, A copolymer resin obtained by polymerizing 0.1 to 40% by weight of a monomer having a functional group capable of forming an anion and 9.9 to 94.9% by weight of another monomer. Is a preferred embodiment in terms of maintaining a high polishing rate and reducing dishing. The content of the monomer having a functional group capable of forming an anion is more preferably 5 to 35% by weight.

  Monomers having functional groups capable of forming anions include unsaturated monobasic acids such as acrylic acid, methacrylic acid, and crotonic acid, unsaturated dibasic acids such as itaconic acid, fumaric acid, and maleic acid, and methacrylsulfonic acid. And sulfonic acid-containing monomers such as sodium styrenesulfonate, and phosphoric acid-containing monomers such as 2-methacryloxyethyl acid phosphate, and two or more of them may be used. In particular, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, allyl sulfonic acid, methallyl sulfonic acid, and 2-methacryloylethyl acid phosphate are preferable.

  Other monomers that can be used to synthesize the resin emulsion (B) include hydrophobic vinyl monomers such as styrene, alkyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, Cyano group-containing vinyl monomers such as (meth) acrylonitrile, carboxyl group-containing vinyl monomers such as (meth) acrylic acid, hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl (meth) acrylate, glycidyl (meth) Glycidyl group-containing vinyl monomers such as acrylate, amino group-containing vinyl monomers such as N, N-dimethylaminoethyl (meth) acrylate, acetoacetoxy group-containing vinyl monomers such as acetoacetoxyethyl (meth) acrylate, etc. As other monomers, glass transition of polymer of monomers Calculated value, in the case of using a monomer is 25 ℃ or higher, further easily improved polishing rate.

  The glass transition point (Tg) of the copolymer resin obtained by polymerizing a plurality of monomers can be obtained by calculation using the Fox equation. Here, the Fox formula is to calculate the Tg of the copolymer based on the Tg of the homopolymer of the monomer for each monomer that forms the copolymer. For example, it is described in Bulletin of the American Physical Society, Series 2, Vol. 1, No. 3, p. 123 (1956).

  In order to obtain a high polishing rate, it is also preferable to use a crosslinkable vinyl monomer. Examples of such a crosslinkable vinyl monomer include methylenebis (meth) acrylamide / divinylbenzene / polyethylene glycol chain-containing di (meta). ) Acrylate and the like. Moreover, you may contain a 2 or more vinyl group as a crosslinkable vinyl monomer. The content of the crosslinkable vinyl monomer is preferably 1 to 15% by weight with respect to the total weight of all the monomers in the composition. The weight of the resin derived from the monomer having a functional group capable of forming an anion is 0.1 to 40% by weight, preferably 0, based on the total weight of the resin components in the composition of the resin emulsion (B). 0.5 to 35% by weight, more preferably 1 to 30% by weight.

  A surfactant or a water-soluble polymer can be appropriately used for the purpose of improving the polymerization stability and storage stability of the resin emulsion (B). Examples of the surfactant include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. Particularly preferred surfactants are those containing no metal.

  Anionic surfactants that do not contain metals include dodecylbenzene sulfonic acid, lauryl sulfuric acid, alkyl diphenyl ether disulfonic acid, alkyl naphthalene sulfonic acid, dialkyl sulfosuccinic acid, stearic acid, oleic acid, dioctyl sulfosuccinate, polyoxyethylene alkyl ether Examples thereof include ammonium salts such as sulfuric acid, polyoxyethylene alkylphenyl ether sulfuric acid, and tert-octylphenoxyethoxypolyethoxyethyl sulfuric acid.

  Further, many nonionic surfactants containing no metal generally have an ethylene glycol chain as a hydrophilic group and do not contain a metal. For example, polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene oleyl phenyl ether, polyoxyethylene nonyl phenyl ether, oxyethylene oxypropylene block copolymer, tert-octylphenoxyethyl polyethoxyethanol, nonylphenoxyethyl poly Examples include ethoxyethanol.

  Further, as the cationic surfactant not containing metal, for example, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, disaryldimethylammonium chloride, alkylbenzyldimethylammonium chloride, laurylbetaine, stearylbetaine, lauryldimethyl Examples thereof include amine oxide, lauryl carboxymethylhydroxyethyl imidazolinium betaine, coconut amine acetate, stearylamine acetate, alkylamming anidine polyoxyethanol, and alkylpicolinium chloride. These dispersing agents can select 1 type (s) or 2 or more types.

(Particle size)
The average particle diameter of the resin emulsion (B) containing the water-soluble resin (A) measured by a dynamic light scattering method (for example, using a dense particle size analyzer FPAR-1000; manufactured by Otsuka Electronics Co., Ltd.) is 40 to 40 A thickness in the range of 500 nm is preferable from the viewpoint of high polishing rate and dishing suppression. A particularly preferred range is 50 to 300 nm. When the particle size is 40 nm or less, dishing can be suppressed, but a high polishing rate that is industrially applicable may not be obtained. Although the said emulsion can also be used independently, 2 or more types of emulsion can be mixed and used. In addition, by mixing two or more types of emulsions having a difference in average particle size of 30 nm or more, a higher polishing rate can be obtained and an increase in dishing can be suppressed as compared with the case where each emulsion is used alone.

(Use of polishing composition)
Although the composition containing the resin emulsion (B) containing the water-soluble resin (A) having an amide group can be used for various polishing applications in the field of electronic information materials, the composition is used for polishing semiconductor wafers. The case will be described in detail.

  In general, in a semiconductor device manufacturing method, after forming a semiconductor circuit on one surface of a semiconductor wafer, supplying a slurry of a polishing composition on the surface (circuit surface) on which the semiconductor circuit is formed However, for example, a polishing apparatus shown in FIG. 2 is used to polish a Cu film or a Cu alloy film formed on a substrate. That is, for example, a polishing cloth (polishing pad) 2 is coated on the turntable 1. A supply pipe 3 for supplying the slurry is disposed above the polishing pad 2. A substrate holder 5 having a support shaft 4 on its upper surface is disposed above the polishing pad 2 so as to be movable up and down and rotatable. In such a polishing apparatus, the holder 5 holds the substrate 6 so that its polishing surface (for example, Cu film) faces the pad 2, while supplying the polishing slurry 7 from the supply pipe 3, A Cu film on the substrate is polished by applying a desired load toward the polishing pad 2 by the support shaft 4 and rotating the holder 5 and the turntable 1 in opposite directions.

(Method for preparing slurry for polishing)
The above-mentioned resin emulsion (B) is dispersed in water, and if necessary, an oxidizing agent (preferably hydrogen peroxide) or a water-soluble compound (preferably carboxylic acid) that can form a complex with the metal to be polished. A slurry prepared by adding an organic acid, an amine, an amino acid, ammonia, etc.), an anticorrosive (preferably a benzotriazole derivative and / or an aromatic compound having a carboxyl group), an additive for suppressing foaming, etc. Although it can be suitably used, from the viewpoint of suppressing the generation of high polishing rate and dishing, a more preferred embodiment is one containing at least one oxidizing agent and one or more organic acids, and more preferably at least one. It further contains a seed corrosion inhibitor.

  In addition to the above-mentioned oxidizing agents, organic acids and anticorrosives, additives that suppress foaming in order to improve the uniformity of the polishing rate within the wafer surface and to suppress clogging of the slurry in the slurry supply line An embodiment in which at least one (preferably polyethylene glycol type nonionic surfactant, emulsion of fatty acid ester, polyether nonionic surfactant) is further contained is particularly preferable.

  The method of preparing the slurry is not particularly limited, but an aqueous dispersion of a water-soluble compound capable of forming a complex with a pH-adjusted metal to be polished is agitated and mixed little by little with an aqueous dispersion of a resin emulsion whose pH is adjusted. Then, a stable slurry is formed, and then the additives are mixed so that the dispersion state of the slurry is not destabilized and the pH is adjusted again, and then insoluble matters and aggregates are removed to obtain a polishing slurry. It is preferable.

  The resin component of the resin emulsion (B) containing the water-soluble resin (A) in the polishing slurry is preferably 1 to 20% by weight, particularly preferably 1.5 to 10% by weight, based on the total weight of the slurry. . If the content of the resin emulsion (B) is too small, the polishing rate may be reduced. On the other hand, if it exceeds 20% by weight, the polishing quality may be deteriorated, such as dishing.

  In order not to cause unnecessary damage to the metal wiring to be polished, it is desirable that (other) metal components do not exist in the polishing slurry. Therefore, when used in such applications, not only the monomers constituting the water-soluble resin (A) and the resin emulsion (B) containing (A), but also the polymerization initiator, surfactant, and metal to be polished It is preferable to use a metal-free substance as a substance that can be contained in the polishing slurry, such as a water-soluble compound, a molecular weight modifier, and a pH adjuster that can form a complex with the polishing slurry.

  Examples of the polymerization initiator not containing metal include organic peroxides such as hydrogen peroxide, ammonium persulfate, cumene hydroperoxide, t-butyl hydroperoxide, and benzoyl peroxide, azobiscyanovaleric acid, 2,2′- Examples include azo compounds such as azobis (2-aminodipropane) dibasic acid salt, and one or more of these can be selected and used.

The polymerization initiator is preferably water-soluble, and ammonium persulfate, azobiscyanovaleric acid, 2,2′-azobis (2-aminodipropane) dibasic acid salt is preferably used.
The amount of the polymerization initiator used is generally 0.1 to 5 parts by weight with respect to 100 parts by weight of the monomer to be polymerized.

(Water-soluble compound that can form a complex with the metal to be polished)
Water-soluble compounds that can form complexes with the metal to be polished include carboxylic acids such as acetic acid, oxalic acid, malonic acid, malic acid, tartaric acid, succinic acid, citric acid, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, and triethylamine. And the like, amino acids such as glycine, aspartic acid and glutamic acid, ketones such as acetylacetone, ammonia and the like.
Of these, carboxylic acids, amines, amino acids, and ammonia are preferable, and oxalic acid, malonic acid, tartaric acid, and glycine are more preferable.

  The amount of the water-soluble compound that can form a complex with the metal to be polished is preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the polishing slurry. If it is less than 0.1% by weight, the effect may not be sufficiently exerted, and the target polishing rate may not be achieved. On the other hand, if the content is more than 10% by weight, the metal to be polished may excessively form a complex and elute, which may promote dishing.

(Oxidant)
Examples of the oxidizing agent include hydrogen peroxide, ammonium persulfate, and potassium persulfate, and hydrogen peroxide is preferably used.
The addition amount of the oxidizing agent is preferably in the range of 0.1 to 10% by weight and more preferably in the range of 1 to 5% by weight with respect to the total weight of the polishing slurry. If the addition amount of the oxidizing agent is less than 0.1% by weight, the chemical reaction between the metal to be polished and the water-soluble resin (A) does not proceed and the intended polishing rate may not be achieved. On the other hand, if the addition amount of the oxidizing agent exceeds 10% by weight, an acid k film is formed on the surface of the metal to be polished and passivated, and polishing may not proceed.

(PH of slurry for polishing)
The pH of the polishing slurry is preferably in the range of 7-11, more preferably in the range of 7-9. When the polishing slurry has a pH of less than 7, corrosion of the metal to be polished proceeds and metal ions are likely to elute, so that the formation of defects such as dishing and fangs may not be sufficiently suppressed. If the pH exceeds 11, the insulating film may be dissolved or partially decomposed when the semiconductor insulating film, which is the end point of polishing, and the metal film to be polished are on the same plane.

(PH adjuster)
A conventionally known pH adjusting agent used for adjusting the pH of the polishing slurry can be used. Metal-free basic substances are preferably used, and amines such as ammonia, methylamine, dimethylamine, triethylamine, ethylamine, dimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, tetramethylammonium hydroxide, water One or more pH adjusting agents selected from alkyl ammonium salts such as tetraethylammonium oxide can be particularly preferably used.
As the pH adjuster, the same substance as the water-soluble compound capable of forming a complex with the metal to be polished is used for the two purposes of adjusting the pH of the polishing slurry and forming a complex with the metal to be polished. You may do it.

(About additives to suppress foaming)
As an additive for suppressing foaming, silica silicone, metal soap, amide, polyether, polyalkylene glycol, block copolymer, etc. can be used. good. A mixture of a polyethylene glycol type nonionic surfactant or the like, or an emulsion of mineral oil, wax, fatty acid ester or the like is particularly preferable for suppressing foaming during polishing.

(Other additives)
Other additives may include additives such as anticorrosives, wetting agents, antistatic agents, preservatives, UV absorbers, light stabilizers, penetrants, fluidity improvers, etc. As the additive used for the slurry for the use, it is preferable to appropriately select an additive that does not contain a metal. For example, as an anticorrosive agent, nitrogen-containing heterocyclic compounds such as benzotriazole, quinaldic acid, and quinolinic acid, and aromatic amino acids such as phenylalanine may be added alone or in combination.

The additive can be added before, during or after polymerization of the water-soluble resin (A), and the amount and type of the additive affects the performance of the composition. Unless otherwise specified, there is no particular limitation.

  Hereinafter, although an example explains more concretely, the present invention is not limited by these examples. In the examples, the number of parts and% all represent parts by weight and% by weight unless otherwise specified.

<Method for producing water-soluble resin (A) having amide group>
A separable flask equipped with a stirrer and reflux cooling was charged with 200 parts by weight of distilled water, replaced with nitrogen gas, and then heated to 75 ° C. Next, after adding 2.0 parts of ammonium persulfate, a mixture of a vinyl monomer having the composition (% by weight) shown in Table 1 and 200 parts by weight of distilled water was continuously added over 2 hours with stirring. The mixture was aged at the same temperature for 2 hours to complete the polymerization, and water-soluble resins (A-1) to (A-3) were obtained.

<Method for producing resin emulsion containing water-soluble resin (A)>
A separable flask equipped with a stirrer and reflux cooling was charged with distilled water and a water-soluble resin (A-1), (A-2) or (A-3) having an amide group, and replaced with nitrogen gas. The temperature rose. Next, after adding ammonium persulfate, an emulsion composed of a monomer having a composition ratio described in Table 2 (b-1 to b-6), distilled water, and ammonium lauryl sulfate was added to all the resin components described in Table 3. The emulsion is continuously added to the flask over 4 hours with stirring so that the content (%) of the water-soluble resin (A) with respect to the weight is reached, and is further maintained for 4 hours to complete the polymerization. A resin emulsion (B) containing a water-soluble resin (A) having the composition (% by weight) described in Table 3 was obtained. Table 3 shows the weight ratio of the raw materials of each component.

<Method for producing resin emulsion not containing water-soluble resin (A)>
(Manufacturing method of B-7)
A separable flask equipped with a stirrer and reflux cooling was charged with 360 parts by weight of distilled water and 0.1 part by weight of ammonium lauryl sulfate, and was replaced with nitrogen gas, and then heated to 80 ° C. Next, after adding 2 parts by weight of ammonium persulfate, a vinyl monomer having the following composition, 40 parts by weight of distilled water and an emulsion of 0.1 part of ammonium lauryl sulfate were continuously added over 3 hours, and the mixture was further maintained for 3 hours. To complete the polymerization. A copolymer emulsion (B-7) having a solid content of 20.0% was obtained.
(Vinyl monomer emulsion)
Styrene 35.0 parts Acrylonitrile 60.0 parts Methacrylic acid 5.0 parts

<Preparation and evaluation of polishing slurry>
(Examples 1-5, Comparative Examples 1-2)
The organic acid aqueous solution neutralized with ammonia was added dropwise to a slurry containing 10% by weight (in terms of solids) of the resin emulsion (B) produced in Examples 1 to 5 and Comparative Examples 1 to 2, and 1 mol / l. The pH was adjusted with aqueous ammonia and diluted with pure water so that the resin concentration was 5.0% by weight. Other components, oxidizing agents, water-soluble compounds capable of forming complexes with metals, anticorrosives, antifoaming agents, and the like, which are added as appropriate in each example, have the concentrations shown in Table 4 (relative to the slurry). Was added as follows. The antifoaming agents in Table 4 are SN deformer JK, SN deformer 440 (emulsion system), SN deformer 260 (polyethylene glycol system), and SN deformer 477 (amide system), respectively. In addition, the colloidal silica used in Comparative Example 2 is PL-1 manufactured by Fuso Chemical Industries.
Further, the polishing slurry was evaluated by the following method.
1. Polishing rate polishing slurry: Resin emulsion (B) containing a water-soluble resin (A) having an amide group, which is appropriately added with other additives to form a slurry Object to be polished: on a silicon wafer substrate Thermal oxide film 5000 mm / Ta film 300 mm formed by sputtering / plating seed copper film 1500 mm / plating seed copper film 1500 mm / copper film 15000 mm laminated 8 inch silicon wafer, silicon wafer with a wiring pattern ( SEMATECH # 854, film thickness L1: 13000mm, film thickness L2: 300mm)
Polishing machine: MAT-ARW-681M
Polishing pad: IC-1000 / suba400, XY-K groove polishing load: 2.5 psi
Polishing time: 1min
Slurry supply amount: 200cc / min
Plate rotation speed: 100 rpm
Substrate side rotation speed: 97rpm

2. Polishing rate calculation The object to be polished was washed with ultrapure water and subjected to ultrasonic cleaning, then dried, and the film thickness before and after polishing was measured by sheet resistance measurement using a four-terminal probe. The average polishing rate was calculated from the change in film thickness and the polishing time.

3. Dishing measurement After polishing the wafer (SEMATECH # 854) on which the wiring pattern was formed under the above polishing conditions, using a stylus type step gauge, the wiring width (L) was 10 μm, and the insulating film width (S) between the wirings was The amount of depression in the Cu wiring portion in the 10 μm wiring pattern was measured as the dishing amount.

4). Erosion Measurement After polishing a wafer (SEMATECH # 854) with a wiring pattern formed under the above polishing conditions, using a stylus type step gauge, the wiring width (L) is 9 μm and the insulating film width (S) between the wirings is A width of 150 μm from the end of the 1 μm wiring pattern was scanned with a stylus, and the difference in height between the Ta height at the shortest part and the Ta layer located 100 μm from the end was measured as the amount of erosion. The polishing time was increased by 50% of the time required to complete the copper polishing of the portion where no groove was formed, and overpolishing was performed.

As a result, in Example 1, the polishing rate was 3700 A / min, and the dishing was 265 nm. Table 5 shows the evaluation of Examples 2 to 9 and Comparative Examples 1 and 2.

The composition of the present invention is useful as a material for polishing slurry in the field of electronic information materials, particularly in the process of manufacturing semiconductor devices.

It is an example of the wiring pattern grind | polished using polishing composition. It is an example of a polishing apparatus.

Explanation of symbols

L1: Metal film L2: Lower layer 1: Turntable 2: Polishing cloth (polishing pad)
3: Supply pipe 4: Support shaft 5: Substrate holder 6: Substrate 7: Slurry for polishing

Claims (22)

Polishing composition containing the resin emulsion containing water-soluble resin (A) which has an amide group. The polishing composition according to claim 1, wherein the water-soluble resin (A) further has a functional group capable of forming an anion. The polishing composition according to claim 2, wherein the functional group capable of forming an anion is at least one of a carboxyl group, a sulfonic acid group, and a phosphoric acid group. The polishing composition according to claim 2, wherein the functional group capable of forming an anion is a carboxyl group. The polishing composition according to claim 1, wherein an average particle size of the resin emulsion is 40 to 500 nm. The weight of a resin derived from a monomer having a functional group capable of forming an anion is 0.1 to 40% by weight based on the total weight of the resin components in the composition. Polishing composition of -5. The polishing composition according to claim 6, wherein the functional group capable of forming an anion is at least one of a carboxyl group, a sulfonic acid group, and a phosphoric acid group. The polishing composition according to claim 1, wherein the water-soluble resin (A) has an average molecular weight of 500,000 or less. The polishing composition according to claim 1, wherein the weight of the water-soluble resin (A) is from 10 to 90% by weight based on the total weight of the resin components in the composition. The polishing composition according to claim 1, further comprising at least one resin emulsion having an average particle diameter of 30 nm or more. The polishing composition according to claim 1, further comprising at least one of an oxidizing agent, a water-soluble compound capable of forming a complex with a metal, and an anticorrosive. The polishing composition according to claim 11, wherein the anticorrosive agent is a benzotriazole derivative and / or an aromatic compound having a carboxyl group. The polishing composition according to claim 11, wherein the water-soluble compound capable of forming a complex with a metal is an organic acid, an amino acid, ammonia, or a salt thereof. The polishing composition according to claim 1, further comprising an additive for suppressing foaming. The additive for suppressing foaming contains at least one of a polyethylene glycol type nonionic surfactant, an emulsion of a fatty acid ester, and a polyether nonionic surfactant. Polishing composition. A metal film (L1) having a thickness of 0.1 to 30 μm formed to be embedded in a wiring portion in a pattern in which a metal embedded wiring with a width of 9.0 μm and an insulating film with a width of 1.0 μm are alternately formed It is characterized in that the dent amount (erosion amount) of the lower layer (L2) generated when polishing for 1.5 times the time required for polishing until the lower layer (L2) is exposed under the polishing conditions is 10 nm or less. The polishing composition according to claim 1. The polishing composition according to claim 16, wherein the metal film (L1) contains at least one selected from copper, copper alloys and oxides thereof. 18. The polishing composition according to claim 16, wherein the lower layer (L2) contains at least one selected from tantalum, tantalum nitride, tantalum alloy, titanium, titanium nitride, titanium alloy, ruthenium, and ruthenium alloy. . A slurry containing the polishing composition according to claim 1. The slurry according to claim 19, wherein the pH is 7-9. The slurry according to any one of claims 19 to 20, which is used for polishing a semiconductor wafer. 23. In a method of manufacturing a semiconductor device, after forming a semiconductor circuit on one surface of a semiconductor wafer, the circuit surface is polished while supplying the slurry according to claim 21 to the surface (circuit surface) on the side where the semiconductor circuit is formed. The manufacturing method characterized by including a process.

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