JP2005167016A - Slurry for polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slurry for polishing that is used to manufacture a semiconductor device including copper and can significantly suppress corrosion or scratch on the metal surface, dishing, and erosion even if polishing speed is made high. <P>SOLUTION: The slurry for polishing is used to manufacture a semiconductor device including copper, and it contains organic particles that are polymerized by a dispersant with metallic impurity content of 1 ppm or less and a polymerization initiator with metallic impurity content of 1 ppm or less and sulfur content of less than 5 wt%, and water content. The organic particles is preferably made of a copolymer that is obtained by emulsion polymerization of vinyl-based monomer of 1-50 wt% and other vinyl-based monomer of 99-50 wt% in terms of weight of whole monomer, and furthermore it preferably contains a complexing agent and an oxidant. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing slurry used for manufacturing a semiconductor device having copper. More specifically, the present invention relates to a polishing slurry used for polishing for forming a copper wiring of a semiconductor device and capable of being polished and flattened without causing corrosion or scratches on a copper surface.

  In recent years, in the wiring process of manufacturing semiconductor devices, a groove for forming a wiring is formed on the insulating film, the metal film for wiring is buried by plating or the like, the excess metal film is removed, and the insulating film surface including the metal wiring As a technique for flattening, CMP (Chemical and Mechanical Polishing) is used. This is a method of mechanically polishing using a slurry in which abrasive grains are dispersed.

  In the CMP technique, conventionally, a slurry containing a metal oxide such as ceria or alumina or an inorganic abrasive such as silica is used. However, these inorganic abrasive grains are high in hardness, and when polishing a low-hardness metal film such as copper, it is called scratches on the metal surface called scratches or dishing, and the metal film in the wiring part is excessive in the center. Phenomenon that is formed into a concave cross-section by being polished, and called erosion, the cross-section concave shape by polishing near the center of the dense part of the wiring pattern, including the insulating film that is the underlying layer The phenomenon that is formed in this occurs, has become a big problem to be solved.

Currently, in order to improve the performance of semiconductors, the 1/2 wiring width on the insulating film is further miniaturized from 130 nm to 90 nm and further to 65 nm, and the surface of the insulating film to be polished has a more complicated structure. It has become. As the wiring width becomes finer, scratches on the metal surface due to scratches cause disconnection, and dishing and erosion cause increases and variations in wiring resistance, as well as short-circuits with the wiring formed in the upper layer. This causes a significant decrease in the reliability of the semiconductor device and a significant decrease in yield.
This scratch is caused by the hardness of the abrasive grains and partial overpolishing caused by the presence of aggregates of abrasive grains.

The dishing is caused by excessive polishing with hard abrasive grains, pH adjustment for promoting elution of the metal surface to increase the polishing rate, and addition of additives.
In addition, erosion is caused by low polishing selectivity with an underlayer such as excessive polishing with hard abrasive grains or a barrier layer that prevents diffusion of an insulating film or metal.

    In order to solve these problems, in the case of inorganic abrasive grains, a polishing liquid capable of polishing on the neutral to alkaline side where metals are not eluted and the silica is softer than alumina is being developed. However, for example, when silica is used as abrasive grains, scratches are reduced as compared with alumina. However, since inorganic abrasive grains are used, generation of scratches, dishing and erosion cannot be prevented and a fundamental solution has not been achieved. Japanese Patent No. 3172008 discloses a method of using organic polymer compound particles as abrasive grains. Since the organic polymer used here is an abrasive having a component having no reactive functional group such as a methacrylic resin or a polystyrene resin, and does not contain an oxidizing agent that oxidizes the metal surface, A chemical action does not work at all with the metal film that is the object to be polished, and a necessary and sufficient polishing rate is not obtained in the wiring process of manufacturing a semiconductor device. Furthermore, if the organic polymer that is the abrasive particles does not have a functional group, the dispersibility in the solvent as the main component of the polishing liquid is poor, and the occurrence of uneven polishing due to partial formation of aggregates of particles, In addition, variations in the polishing rate become a problem. Furthermore, when the polishing liquid is stored for a long period of one week or longer, there is a problem that precipitation occurs.

Further, when organic particles are produced, the presence of elements such as Na and S in the polymerization initiator and the dispersant may cause corrosiveness to copper.
Japanese Patent No. 3172008

  The present invention has a metal polishing slurry, particularly a copper wire, which can increase the polishing rate and can significantly suppress the occurrence of corrosion, scratching, dishing and erosion of the metal surface even when the polishing rate is increased. An object of the present invention is to provide a polishing slurry used for manufacturing a semiconductor device.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, the polishing slurry of the present invention is specified as follows.
(1) A polishing slurry comprising organic particles, a complexing agent, an oxidizing agent and water, wherein the slurry has a metal atom content of 1 ppm or less and a sulfur atom content of 10 ppm or less.
(2) Organic particles are produced using a dispersant having a metal atom content of 1 ppm or less and a polymerization initiator having a metal atom content of 1 ppm or less and a sulfur atom content of less than 5% by weight. A slurry for polishing.
(3) The polishing slurry according to (1) or (2), wherein the dispersant is ammonium alkyldiphenyl ether disulfonate.
(4) The polishing slurry according to (2), wherein the polymerization initiator is azobiscyanocyanovaleric ammonia.
(5) The organic fine particles are based on the weight of all monomers, unsaturated carboxylic acid monomer, hydroxyl group-containing vinyl monomer, amino group-containing vinyl monomer, acetoacetoxy group-containing vinyl monomer, Polymerize a monomer composition containing 1 to 50% by weight of one or more monomers selected from glycidyl group-containing vinyl monomers and 99 to 50% by weight of other vinyl monomers. The polishing slurry according to any one of (1) to (4), wherein the polishing slurry is composed of a copolymer obtained as described above.
(6) The complexing agent is at least one selected from carboxylic acids, amines, amino acids and ammonia, and the pH is in the range of 5 to 11, (1) to (5) The polishing slurry according to any one of the above.
(7) The polishing slurry according to any one of (1) to (6), wherein the oxidizing agent is hydrogen peroxide.

By using the polishing slurry of the present invention, excess copper metal film on the wiring processed insulating film can be polished at a high speed, and the surface of the object to be polished is damaged or scratched due to corrosion or excessive polishing. It is possible to perform polishing without generating unevenness, and polishing with high flatness without irregularities such as dishing and erosion is possible.
Since the polishing slurry of the present invention is composed of an emulsion having excellent dispersibility, separation with the passage of time (generation of supernatant and precipitate) and formation of aggregates do not occur, and a stable polishing rate is always obtained.
Further, in the polishing according to the present invention, the residue of the polishing slurry on the insulating film can be removed by heat treatment and plasma treatment, so that the insulating film is not damaged.

The polishing slurry of the present invention is a polishing slurry containing organic particles, a complexing agent, an oxidizing agent and water, and the metal atom content in the slurry is 10 ppm or less, preferably 1 ppm or less, and the sulfur atom content Is 50 ppm or less, preferably 10 ppm or less.
In the present invention, the metal atom means Na, Cu, Fe, Ca, Mg, Ni, Cr, Al, Sr, Sb, Ce, La, Li, Hf, Co, Ga, V, Mo, or Zr.
(About organic particles)
The metal atom content of the organic particles is preferably 1 ppm or less, more preferably 0.1 ppm or less, and the sulfur atom content is preferably 10 ppm or less, more preferably 0.1 ppm or less. A dispersant having a metal atom content of 1 ppm or less, more preferably 0.1 ppm or less, and a metal atom content of 1 ppm or less, more preferably 0.1 ppm or less, and a sulfur atom content of less than 5 wt%, more preferably 1 wt. By using less than% polymerization initiator, the metal atom content and sulfur atom content in the organic particles can be controlled.
The organic particles desirably have a functional group capable of forming a complex with a metal. Examples of the functional group capable of forming a complex with a metal include a carboxylic acid group, a hydroxyl group, an amine group, a ketone group, a glycidyl group, and an acetoacetoxy group. In particular, carboxylic acid is preferably used.

  The organic particles can be produced, for example, by emulsion polymerization of a monomer having these functional groups and another vinyl monomer copolymerizable therewith. In the case of particularly preferable organic particles having a carboxylic acid group, the carboxylic acid group is dissociated by adding 0.3 mol equivalent or more of an alkaline substance to the unsaturated carboxylic acid in the obtained copolymer emulsion. To form a complex with the metal.

Examples of the unsaturated carboxylic acid used in the present invention 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 monoesters thereof. 1 type or 2 types or more selected from the above, and acrylic acid and methacrylic acid are particularly preferable.
Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. .
Examples of the amino group-containing vinyl monomer include amino group-containing (meth) acrylate monomers containing tertiary amino groups. For example, N, N-dimethylaminoethyl (meth) acrylate, N, N- Examples thereof include dimethylaminopropyl (meth) acrylate, N, Nt-butylaminoethyl (meth) acrylate, N, N-monomethylaminoethyl (meth) acrylate, and the like.
Moreover, N-aminoalkyl (meth) acrylamide containing a tertiary amino group is mentioned, for example, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethylamino. Examples thereof include propyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N-isopropyl (meth) acrylamide and the like.
Examples of the acetoacetoxy group-containing vinyl monomer include acetoacetoxyethyl (meth) acrylate, and examples of the glycidyl group-containing vinyl monomer include glycidyl (meth) acrylate.

  The amount of the monomer having a functional group that forms a complex with these metals is preferably 1 to 50 parts by weight, more preferably 3 to 45 parts by weight, and still more preferably, of all monomer components in the copolymer. 5 to 40 parts by weight. If it is less than 1 part by weight, the intended polishing rate cannot be obtained, and if it exceeds 50 parts by weight, the water resistance and alkali resistance may be poor.

Examples of other vinyl monomers that can be copolymerized with the above-mentioned monomer having a functional group that forms a complex with a metal include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and (meth) acrylic. Methyl methacrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, ( (Meth) acrylic acid n-hexyl, (meth) acrylic acid octyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid esters such as isobornyl acrylate, vinyl esters such as vinyl acetate and vinyl propionate, Halogenation of vinylcyan compounds such as (meth) acrylonitrile, vinyl chloride, vinylidene chloride Sulfonyl compound. In addition to the unsaturated carboxylic acid, (meth) acrylamide or N-methylol (meth) acrylamide is used as a functional group monomer as required.
The amount of other vinyl monomers used is preferably 99 to 50% by weight, more preferably 95 to 70% by weight.

  Such organic particles may or may not swell as a whole when an alkaline substance is added, either of which may be used. In addition, swelling shown here means that the average particle diameter of the primary particles is increased by including water or other water-soluble substances in the particles without being decomposed or aggregated.

In order to adjust the degree of swelling of the organic particles by adding an alkali, a crosslinkable monomer can be copolymerized as necessary. Examples thereof include monomers containing two or more polymerizable unsaturated bonds in one molecule, divinylbenzene, butadiene, ethylene glycol dimethacrylate, trimethylol alloban trimethacrylate, ethylene glycol diacrylate, 1, Examples include 3-butylene glycol dimethacrylate and diacrylate. The amount of the crosslinkable monomer used is 20% by weight or less, preferably 10% by weight or less, and is appropriately used depending on the type of unsaturated carboxylic acid, the amount used, the type of vinyl copolymer, and the like.
In addition, these organic particles may be used independently and may be used in combination of 2 or more types.

The content of the fine particles in the polishing slurry varies depending on the organic fine particles, but is preferably 0.1 to 20% by weight. If it is less than 0.1% by weight, the effect of the organic fine particles cannot be sufficiently exerted, so that the intended polishing rate may not be achieved. On the other hand, if it exceeds 20% by weight, the viscosity of the abrasive is high, and it may be difficult to supply the abrasive at a constant speed during polishing.
Examples of the dispersant having a metal atom content of 1 ppm or less include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, (meth) acrylic acid (co) polymer, poly (meth) acrylamide (co) polymer, ethylene glycol, and the like. As the surfactant, anionic, nonionic, and cationic systems are exemplified. The anionic surfactant has an acidic group such as sulfonic acid or carboxylic acid as a hydrophilic group, but a counter ion that is not a metal salt such as Na or K can be used. Generally ammonium salts such as 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 sulfuric acid And ammonium salts such as polyoxyethylene alkyl ether sulfuric acid, polyoxyethylene alkyl phenyl ether sulfuric acid, dialkyl sulfosuccinic acid, stearic acid, oleic acid, and tert-octylphenoxyethoxy polyethoxyethyl sulfuric acid.

  Further, many nonionic surfactants 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 examples of cationic surfactants include lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, alkylbenzyl dimethyl ammonium chloride, lauryl betaine, stearyl betaine, lauryl dimethylamine oxide, lauryl. Examples thereof include carboxymethyl hydroxyethyl imidazolinium betaine, coconut amine acetate, stearyl amine acetate, alkyl amidine anidine polyoxyethanol, alkyl picolinium chloride and the like.

These dispersing agents can select 1 type (s) or 2 or more types. The anionic surfactant having a counter ion metal is widely used for the purpose of improving the dispersion stability of the organic particles. However, the dispersion stability of organic particles can be improved by increasing the amount of carboxylic acid.
The amount of the dispersant used is preferably 0.05 to 5% by weight based on the total weight of the (co) polymerized monomer.

Use of a polymerization initiator having a metal atom content of 1 ppm or less and a sulfur atom content of less than 5% by weight is preferable because the metal wiring surface can maintain good smoothness before and after polishing. Examples of the polymerization initiator satisfying such conditions include hydrogen peroxide, azobiscyanovaleric acid, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (N— Phenylamidino) propane] dihydrochloride, 2,2′-azobis {2- [N- (4-chlorophenyl) amidino] propane} dihydrochloride, 2,2′-azobis {2- [N- (4-hydroxy Phenyl) amidino] propane} dihydrochloride, 2,2′-azobis [2- (N-benzylamidino) propane] dihydrochloride, 2,2′-azobis [2- (N-allylamidino) propane] dihydrochloride Salt, 2,2′-azobis {2- [N- (2-hydroxyethyl) amidino] propane} dihydrochloride, azobisisobutyronitrile, 2,2′-azobis {2-methyl-N- [1 , 1-bis (hydro Cymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide}, 2,2′-azobis [2- Azo compounds such as methyl-N- [2-hydroxyethyl] propionamide], 2,2′-azobis (isobutylamide) dihydrate; cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, t Organic peroxides such as -butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, lauroyl peroxide, and the like can be used, and one or more of these can be selected. The initiator is preferably water-soluble, and azobiscyanovaleric acid and 2,2′-azobis (2-amidinopropane) dihydrochloride are more preferable. The amount of a general initiator used is preferably 0.1 to 5% by weight based on the total weight of the (co) polymerized monomer.
The additive can be used before, during, or after polymerization. Examples of additives include wetting agents, antistatic agents, antioxidants, preservatives, UV absorbers, light stabilizers, fluorescent brighteners, colorants, penetrants, foaming agents, mold release agents, and foam inhibitors. An agent, an antifoaming agent, a fluidity improver, a thickener and the like can be mentioned, but a material containing no metal can be appropriately selected.

  In addition, when obtaining organic particles, molecular weight regulators such as mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, allyl compounds such as allyl sulfonic acid, methallyl sulfonic acid, and soda salts thereof as necessary It can also be used.

  The organic particles can be produced based on conventionally known emulsion polymerization methods, suspension polymerization methods, and mechanical emulsion methods. For example, in the emulsion polymerization method, there are a method in which various monomers are charged in a batch in the presence of a dispersant and an initiator, and a method in which polymerization is performed while monomers are continuously supplied. The polymerization temperature at that time is usually 30 to 90 ° C., and an aqueous dispersion of organic particles is substantially obtained. The emulsion polymerization method is a more preferable polymerization method because organic particles having a small particle diameter and excellent dispersion stability can be obtained.

(Complexing agent)
A complexing agent is a water-soluble compound capable of forming a complex with a metal, and includes carboxylic acids such as acetic acid, oxalic acid, malic acid, tartaric acid, succinic acid, citric acid, methylamine, dimethylamine, triethylamine, ethylamine, Examples include amines such as diethylamine and triethylamine, amino acids such as glycine, aspartic acid, glutamic acid and cysteine, ketones such as acetylacetone, and N-containing cyclic compounds such as imidazole. Preferably, oxalic acid, malic acid, and ethylamine are used.
The content in the polishing slurry varies depending on the water-soluble complex-forming compound, but is preferably in the range of 0.1 to 10% by weight in the polishing slurry. Within this range, the effect can be fully exerted and the target polishing rate can be achieved, and complex formation with the metal to be polished proceeds excessively, and dishing out of the metal to be polished outside the object to be polished is suppressed. can do.
Good metal polishing is performed when the metal of the object to be polished forms a complex with the functional group contained in the organic fine particles and similarly forms a metal complex with the above water-soluble compound. This metal complex may be composed of a ligand of an organic fine particle and a ligand of a water-soluble substance, and the organic fine particle-metal complex formation promotes the formation of a water-soluble substance-metal complex, Organic substance-metal complex formation may promote organic fine particle-metal complex formation.
Examples of the oxidizing agent include permanganic acid compounds such as peracetic acid, perbenzoic acid, and potassium permanganate, and halogen acid compounds such as potassium iodate, and hydrogen peroxide is preferable. The content of the oxidizing agent is preferably in the range of 0.1 to 15% by weight in the polishing slurry, and particularly preferably in the range of 0.5 to 5% by weight. If it is this range, the chemical reaction of a metal and organic particles can advance, the target polishing rate can be achieved, and the oxide film produced | generated on a metal surface will passivate, and polishing does not stop progressing.

(PH)
The polishing slurry of the present invention has a pH of preferably 5 to 11, more preferably 7 to 10. Within this range, metal elution can be suppressed, dishing does not occur, and the semiconductor insulating film and the metal wiring that are the final point of the metal film polishing are on the same plane. It does not dissolve or partially decompose.
The substance used for adjusting the pH of this polishing slurry is not particularly limited, and examples of the alkaline substance include amines such as ammonia, triethylamine, diethylamine, ethylamine, trimethylamine, dimethylamine, and methylamine. Examples of the acidic substance include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as acetic acid, oxalic acid, and citric acid. These pH adjusters may also serve as water-soluble compounds that can be the metal ligands shown above. Moreover, you may use these substances in combination of 2 or more types.

(Manufacture of polishing slurry)
The polishing slurry of the present invention is produced by mixing organic particles, preferably a water-soluble compound, and water and adjusting the pH. The production method is not particularly limited. For example, it is preferable to add an aqueous solution of a water-soluble compound capable of forming a ligand and a metal whose pH has been adjusted to a pH-adjusted resin emulsion, and thoroughly agitate and mix. Thereafter, preferably, an oxidizing agent is gradually added and further stirred and mixed.
Then, after adjusting the final pH and concentration, a method of removing undissolved substances and aggregates by filtration with a filter paper to obtain a slurry for polishing can be mentioned.

(Other additives)
In the present invention, other additives may be added to the polishing slurry as necessary. As additives, polishing accelerators, halogenated compounds containing chlorine, fluorine, iodine, nitrogen-containing heterocyclic compounds such as benzotriazole, quinaldic acid, etc. as protective films for Cu wiring in areas where polishing and corrosion are to be avoided, and Examples thereof include water-soluble polymers such as polyacrylic acid, polyvinyl alcohol, polyethylene glycol, and glucose, and surfactants. You may add these substances individually or in combination of 2 or more types. The addition amount and type are not particularly limited as long as the object of the present invention can be achieved.

Hereinafter, the present invention will be described in detail by way of examples. In the present examples, parts and% represent parts by weight and% by weight unless otherwise specified.
(Measuring method)
1． Particle size distribution measurement of organic particles in polishing composition Particle size distribution measurement method using laser dynamic light scattering principle Measuring device: MICROTRAC UPA / MODEL: 9230 (Leeds & Northrup)
Concentration condition: Sample stock solution Measurement time: 900 seconds
2. After ashing the sample for measuring metal atom content and sulfur atom content such as slurry and organic particles, dissolve in dilute nitric acid and perform quantitative analysis with ICP analyzer (high-frequency plasma emission spectrometer).
3. Polishing Composition Evaluation Method 3-1 Polishing Rate Polishing Slurry: Polishing Composition of the Present Invention Polishing Object: Thermal Oxide Film (SiO ₂ Film) 5000Å Formed on Silicon Substrate by Sputtering Method, Ta Film LGP-15 made by LAPMASTER (platen diameter 340mm)
Head rotation speed (wafer side) 40rpm
Platen rotation speed (pad side) 30rpm
Load 250g / cm ²
Polishing time 1min
Polishing pad IC-1000 (Rodel Nitta)

3-1-1 Polishing Rate Calculation The object to be polished was washed with ultrapure water and subjected to ultrasonic cleaning, 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.
3-1-2 Surface Defect After polishing and polishing the polished object with ultrapure water, the surface was observed with a differential interference microscope at a magnification of 2500 times. Note that scratches on the surface having a length of 0.1 μm or more were judged as scratches.

○: Scratches and scratches 5 or less ×: Scratches and scratches exceeding 5

3-2 Measurement of dishing amount A groove having a thickness of 7000 mm and a width of 100 μm is formed by dry etching on an oxide film on a silicon wafer. Copper is filled in this groove by a plating method to form an object to be polished. After polishing under the polishing essential composition of the present invention and the above polishing conditions, the thickness of the recess at the center of the groove is measured by a cross-sectional SEM photograph. The polishing was completed when the copper polishing of the portion where no groove was formed was completed.
3-3 Measurement of Erosion A number of grooves having a thickness of 7000 mm and a width of 4.5 μm are formed at 0.5 μm intervals on the oxide film on the silicon wafer by dry etching. Copper is filled in this groove by a plating method to form an object to be polished. After polishing with the polishing composition of the present invention and the above polishing conditions, the level difference between the central groove and the grooves on both sides is measured by a cross-sectional SEM photograph. The polishing was completed when the copper polishing of the portion where the groove was not formed on both sides of the groove was completed.
3-4 Evaluation of Storage Stability The abrasive was allowed to stand for 6 hours at atmospheric pressure and room temperature. Thereafter, the state of the abrasive was visually observed.
○: Supernatant, no precipitate generated ×: Supernatant, precipitate generated 3-5 Metal Corrosion Evaluation A silicon wafer on which a copper film is formed is cut into 15 × 25 mm and immersed in an approximately 100 cc polishing slurry for 10 minutes. . The film thickness before and after immersion was measured by sheet resistance measurement using a four-terminal probe, and the average polishing rate was calculated from the change in film thickness and the immersion time.

(Example 1)
(A) Production of organic particles
A Separa flask equipped with a stirrer, thermometer and reflux condenser was charged with 194.7 parts of water and 0.1 part of ammonium alkyldiphenyl ether disulfonate (metal atom content: 0.1 ppm) as a dispersing agent. Raise the temperature to ℃. The internal temperature was kept at 70 ° C., and 4.0 parts of a 10% azobiscyanovaleric acid ammonia neutralized aqueous solution (metal atom content 0.1 ppm, sulfur atom content 0.1 ppm) was added as a polymerization initiator. Separately, 75.0 parts of butyl acrylate, 20.0 parts of methacrylic acid, 5.0 parts of divinylbenzene are mixed with 40 parts of water and 0.1 part of ammonium alkyldiphenyl ether disulfonate to give an emulsion of monomers. The emulsion was dropped into the flask over 4 hours, and then kept at 70 ° C. for 4 hours.
The obtained emulsion had a solid content of 30%, a particle diameter by light scattering of 127.4 nm, and a pH of 4.9. The metal atom content of the organic particles (solid content) was 0.1 ppm, and the sulfur atom content was 0.1 ppm.
(B) Production of abrasives A 10% solution of oxalic acid was adjusted to pH 8.0 using ammonia. This solution was mixed well with the pH-adjusted emulsion of (A), pure water, and 35% hydrogen peroxide, and the organic particle (solid content) concentration was 3.0 wt%, hydrogen peroxide was 2.0 wt%, and oxalic acid 1 It adjusted so that it might become 0.0 wt% and pH8.0. The metal atom content in the slurry was 0.1 ppm, and the sulfur atom content was 0.8 ppm.
The results are shown in Table 1.

(Comparative Example 1)
(C) Manufacture of organic particles
A Separa flask equipped with a stirrer, thermometer and reflux condenser was charged with 194.7 parts of water and 0.1 part of sodium alkyldiphenyl ether disulfonate (metal atom content: 7 × 10 ⁴ ppm) as a dispersing agent, and nitrogen was replaced with stirring. The temperature is raised to 70 ° C. The inner temperature was kept at 70 ° C., and 0.4 parts of ammonium persulfate (metal atom content 2.1 ppm, sulfur atom content 28 wt%) was added as a polymerization initiator, and it was confirmed that it was dissolved. Separately, 79.5 parts of butyl acrylate, 20.0 parts of methacrylic acid and 0.5 part of divinylbenzene are mixed with 40 parts of water and 0.1 part of ammonium alkyldiphenyl ether disulfonate to give an emulsion of monomers. The emulsion was dropped into the flask over 4 hours, and then kept at 70 ° C. for 4 hours.
The obtained emulsion had a solid content of 30%, a particle diameter by light scattering of 135 nm, and a pH of 2.3. The organic atom (solid content) had a metal atom content of 1.7 ppm and a sulfur atom content of 1.8 ppm.
(D) Production of abrasives A 10% solution of oxalic acid was adjusted to pH 8.0 using ammonia. This solution was mixed well with the pH-adjusted emulsion of (A), pure water, and 35% hydrogen peroxide, and the organic particle (solid content) concentration was 3.0 wt%, hydrogen peroxide was 2.0 wt%, and oxalic acid 1 It adjusted so that it might become 0.0 wt% and pH8.0. The metal atom content in the slurry was 3.9 ppm, and the sulfur atom content was 36 ppm.
The results are shown in Table 1.

(Comparative Example 2)
The same operation and evaluation as in Example 1 were performed except that the organic fine particles of Example 1 were replaced with commercially available colloidal silica (PL-1 manufactured by Fuso Chemical Co., Ltd.). The results are shown in Table 1.

Claims (7)

A polishing slurry comprising organic particles, a complexing agent, an oxidizing agent, and water, wherein the slurry has a metal atom content of 1 ppm or less and a sulfur atom content of 10 ppm or less. The organic particles are produced using a dispersant having a metal atom content of 1 ppm or less and a polymerization initiator having a metal atom content of 1 ppm or less and a sulfur atom content of less than 5% by weight. The polishing slurry according to claim 1. The polishing slurry according to claim 1 or 2, wherein the dispersant is ammonium alkyldiphenyl ether disulfonate. The polishing slurry according to claim 2, wherein the polymerization initiator is ammonia azobiscyanocyanovalerate. Organic particles based on the weight of all monomers, unsaturated carboxylic acid monomer, hydroxyl group-containing vinyl monomer, amino group-containing vinyl monomer, acetoacetoxy group-containing vinyl monomer, glycidyl group-containing Obtained by polymerizing a monomer composition containing 1 to 50% by weight of one or more monomers selected from vinyl monomers and 99 to 50% by weight of other vinyl monomers. The polishing slurry according to any one of claims 1 to 4, wherein the polishing slurry is composed of a copolymer obtained. 6. The complexing agent is at least one selected from carboxylic acids, amines, amino acids, and ammonia, and the pH is in the range of 5-11. Slurry for polishing. The polishing slurry according to any one of claims 1 to 6, wherein the oxidizing agent is hydrogen peroxide.