JP2006080406A - Composition for polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a decrease in a polishing rate to the minimum regardless of long-term polishing service. <P>SOLUTION: In a composition for polishing, a spheroidal particle whose sphericity is 0.9 or larger and 1.0 or smaller and a non-spheroidal particle whose sphericity is 0.3 or larger and less than 0.9 are dispersed in a water-based dispersive medium, and the weight ratio of the spheroidal particle to the non-spheroidal particle ranges from 2/98 to 35/65. The spheroidal particle and non-spheroidal particle are made of silica particles, the average grain size of the spheroidal particle ranges from 20 to 150 nm, and that of the non-spheroidal particle ranges from 5 to 100 nm. The pH of the composition for polishing ranges from 8 to 11.5, and the amount of basic impurities contained in the composition for polishing is 100 ppm or smaller to SiO<SB>2</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polishing composition in which spherical particles and non-spherical particles are dispersed in an aqueous dispersion medium.

  Various integrated circuits are used in computers and various electronic devices, and with these miniaturization and high performance, higher density and higher performance of circuits are required. Among them, for example, a semiconductor integrated circuit conventionally uses a multilayer wiring to increase the degree of integration of the semiconductor integrated circuit. Such a multilayer wiring is usually formed on a first insulating film on a substrate such as silicon. After forming a thermal oxide film, a first wiring layer made of an aluminum film or the like is formed, and an interlayer insulating film such as a silica film or a silicon nitride film is deposited thereon by a CVD method or a plasma CVD method. A silica insulating film for planarizing the interlayer insulating film is formed on the interlayer insulating film by the SOG method, and a second insulating film is further deposited on the silica insulating film as necessary. It is manufactured by forming the second wiring layer. In the wiring made of the aluminum film, the wiring such as aluminum is oxidized at the time of sputtering when forming the multilayer wiring, and the resistance value is increased to cause a conductive failure. Further, since the wiring width cannot be reduced, there is a limit to forming a higher density integrated circuit. Further, in recent years, long-distance wiring such as a clock line and a data bus line has increased wiring resistance with an increase in chip size, and an increase in propagation delay time of electric signals (RC delay time = resistance capacity) has become a problem. . For this reason, it is necessary to replace the wiring with a material having a lower resistance.

  It has also been proposed to perform Cu wiring instead of conventional Al or Al alloy wiring. For example, after forming a wiring groove in an insulating film on a substrate in advance, Cu wiring is formed by electrolytic plating, CVD, or the like. Methods for doing this are known. In the formation of a wiring pattern such as copper, since a process by a dry etch process is difficult, a damascene process using a chemical mechanical polishing method (hereinafter sometimes referred to as CMP) is applied, and insulation on a substrate is performed. A wiring groove is formed in the film in advance, and copper is buried in the wiring groove by an electrolytic plating method, a CVD method or the like, and then the upper end surface is polished by CMP and flattened to form a wiring. Specifically, for example, as shown in FIG. 1A, a wiring interlayer film (insulating film) is formed on a substrate such as a silicon wafer, and metal wiring is formed on the wiring interlayer film (insulating film). A barrier metal layer such as TaN is formed by a sputtering method or the like as necessary, and then copper for metal wiring is formed by a CVD method or the like. Here, when a barrier metal layer such as TaN is provided, it is possible to prevent a decrease in insulation of the interlayer insulating film due to diffusion or erosion of copper or impurities into the interlayer insulating film. And copper adhesion can be improved.

  Next, unnecessary copper and barrier metal (parts above the coplanar surface indicated by the arrow in FIG. 1A) formed by CMP are removed by polishing, and the upper surface is made as much as possible. Planarization is performed to form a copper wiring / circuit pattern leaving a metal film only in the groove (see FIG. 1B). In CMP, a polishing pad is generally mounted on a circular platen having a rotation mechanism, and a polishing material is rotated as shown in FIG. The copper and the barrier metal in the upper part of the coplanar surface are polished and removed by contacting the polishing pad while applying a load. In addition, abrasives used in CMP are usually spherical polishing particles having an average particle diameter of about 200 nm made of a metal oxide such as silica and alumina, and oxidation for increasing the polishing rate of wiring / circuit metals. Agent, an additive such as an organic acid, and a solvent such as pure water.

As shown in FIG. 1A, the surface of the material to be polished has a step (unevenness) due to the wiring groove pattern formed in the underlying insulating film. However, it has been demanded that the surface is polished to be a flat polished surface, and it has been desired that the polishing rate does not decrease even when polished for a long time.
JP-A-2003-529622 (Patent Document 1) discloses a polishing agent containing spherical, separated silica particles which are not connected to each other by a bond, and a) 5-95% by weight of silica particles having a size of 5 to 50 nm. And b) an invention relating to an abrasive comprising 95-5% by weight of silica particles with a size of 50-200 nm, but with the entire particle having a bimodal particle size distribution. It is described that a polishing rate can be obtained.

  Japanese Patent Application Laid-Open No. 2003-297777 (Patent Document 2) discloses fractionated silicon oxide particles having a particle size of 50 to 120 nm, fractionated silicon oxide particles having a particle size of 30 to 50 nm, and particle size of 15 to 30 nm. The fraction of silicon oxide particles is present in a weight ratio of 1: 0.2 to 2: 0 to 1.5, and the concentration of silicon oxide particles in the polishing composition is 1 to 25% by weight. Further, a weak acid and / or a strong base using a weak acid and / or a weak base in which the logarithm of the reciprocal of the acid dissociation constant at 25≡ is in the range of 8.0 to 12.0, a strong acid and a weak base, or a weak acid An invention relating to a polishing composition prepared as a buffer solution having a buffering action at a pH of 8.7 to 10.6 by containing a salt of any combination of weak bases is described. According to the composition, the silicon wafer , Without reducing the quality of the polished surface plane and an end face of a semiconductor device substrate, it is described that can be stably fast polishing.

  Japanese Patent Application Laid-Open No. 2001-323254 (Patent Document 3) is a polishing composition obtained by mixing an abrasive and water, and has an integrated particle size distribution (number basis) from the small particle size side of the abrasive. Polishing liquid composition and particles having a ratio (D90 / D50) of particle size (D90) of 90% to particle size (D50) of 50% of 1.3 to 3.0 and D50 of 10 to 600 nm A polishing composition comprising a mixture of two or more types of abrasives having different diameters (D50) and water, wherein the abrasive having the largest D50 relative to D50 (D50S) of the smallest abrasive (D) (D50) B) The ratio of D50 (D50L) (D50L / D50S) is 1.1 to 3.0, and the blending ratio of A and B (A / B (weight ratio)) is 90/10 to 10/90. There is a description about a certain polishing composition, and the polishing composition improves the polishing rate. In addition, it is described that a high-quality magnetic disk substrate having excellent surface properties and improved surface smoothness such as surface roughness (Ra) can be produced with high production efficiency with few surface defects such as scratches and pits. ing.

Japanese Patent Application Laid-Open No. 2001-11433 (Patent Document 4) discloses a metal composition for bonding a spherical colloidal silica particle having an average particle diameter of 10 to 120 nm and a spherical colloidal silica particle in an aluminum disk polishing composition containing a silica sol. A ratio D ₁ / D ₂ consisting of oxide-containing silica and measuring particle diameter (D ₁ nm) by dynamic light scattering method and average particle diameter of spherical colloidal silica particles (measured particle diameter by nitrogen adsorption method / D ₂ nm) there be three or more, the D ₁ is 50 to 800 nm, it beaded colloidal silica particles spherical colloidal silica particles are connected to only one plane is a stable silica sol dispersed in water, and said number pearl-like colloidal silica particles, sets polishing of aluminum disks, characterized in that it comprises a SiO ₂ concentration of 0.5 to 50 wt% In the polishing of an aluminum disk, a trivalent iron compound is added as a polishing accelerator to a polishing composition containing beaded colloidal silica particles such as the polishing composition. There is a description that the polishing rate is significantly faster than the polishing composition to which a metal salt other than the iron compound is added, and the resulting polished surface is good.

  The present inventors suppressed dishing (overpolishing) and bonded two or more primary particles having an average particle diameter in the range of 5 to 300 nm as polishing particles capable of polishing the substrate surface flatly. Abrasive particles containing irregularly shaped particles were proposed (Japanese Patent Laid-Open No. 2003-133267 (Patent Document 5)). Here, the “shaped particle group” is not a particle group in a normal form in which primary particles are aggregated into a spherical shape or aggregated into a lump, but two or more primary particles are combined. This refers to a group of particles in the form of chains, fibers, or other irregular shapes. Such abrasive particles have a lower polishing rate than the spherical particles themselves.

  Therefore, for example, in polishing a substrate having irregularities, the polishing of the concave portion is suppressed until the upper end surface of the convex portion becomes the same level as the bottom surface of the concave portion, and the upper end surface of the convex portion is polished to the same level as the bottom surface of the concave portion. After that, both the convex part and the concave part can be polished at the same polishing rate, and the polished surface has no unevenness and is excellent in flatness, and even if it is subjected to polishing for a long time, polishing performance is not easily lowered. A composition for use was desired.

Special table 2003-529662 JP 2003-297777 A JP 2001-323254 A JP 2001-11433 A JP 2003-133267 A

  An object of the present invention is to provide a polishing composition that exhibits excellent polishing performance and that suppresses a decrease in polishing rate to a minimum even when subjected to long-time polishing.

An object of the present invention is to provide a polishing composition in which spherical particles having a sphericity of 0.9 or more and 1.0 or less and non-spherical particles not corresponding to the spherical particles are dispersed in an aqueous dispersion medium. The problem is solved by the polishing composition in which the weight ratio of the spherical particles to the non-spherical particles is in the range of 2/98 to 35/65.
The spherical particles and non-spherical particles are preferably silica particles, the average particle diameter of the spherical particles is in the range of 20 to 150 nm, and the average particle diameter of the non-spherical particles is in the range of 5 to 100 nm. preferable.
Moreover, about pH of polishing composition of this invention, it is desirable that pH exists in the range of 8-11.5.
The non-spherical particles in the polishing composition of the present invention are preferably obtained by neutralizing an alkali silicate with an acid, washing the produced silica hydrogel, and growing it by peptization by heat.
The amount of the basic impurities contained in the polishing composition of the present invention is preferably 100 ppm or less with respect to SiO ₂ .

  Since the polishing composition of the present invention contains spherical particles and non-spherical particles in an appropriate ratio, the clear reason is unknown, but these particles are in multipoint contact with the surface to be polished having recesses. In the polishing of a substrate having irregularities, the non-spherical particles are brought into contact with the surface to be polished through the spherical particles, so that the concave portion is polished until the upper end surface of the convex portion is at the same level as the bottom surface of the concave portion. After the upper end surface of the convex portion is polished to the same level as the bottom surface of the concave portion, both the convex portion and the concave portion can be polished at the same polishing rate, and the polished surface has no unevenness and has excellent flatness. In addition, even if the polishing is performed for a long time, the polishing performance is hardly deteriorated, and a laminated integrated circuit or the like can be efficiently formed.

Hereinafter, preferred embodiments of the present invention will be described.
Spherical particles The spherical particles and non- spherical particles of the present invention are composed of inorganic oxides such as silica, alumina, zirconia, titania and ceria, and / or inorganic composite oxides such as silica-alumina and silica-zirconia. Of these, silica particles are particularly preferred from the viewpoint of ease of use.
In the present invention, the term “spherical particle” means a particle having a sphericity in the range of 0.9 or more and 1.0 or less. Here, the sphericity is the ratio (DS / DL) between the maximum particle diameter (DL) and the minor diameter (DS) orthogonal to this in a photographic projection obtained by photographing with a scanning electron microscope. means.

A known manufacturing method is applied as a method for manufacturing the spherical particles. For example, as described in JP-A-63-45114, an aqueous silicic acid solution such as sodium silicate and / or an alkaline aqueous solution and an acidic silicic acid solution are mixed, and the mixed solution SiO ₂ / M ₂ O (M Is adjusted to 2.8-10, the resulting mixture is aged at 60 ° C. or higher to prepare a seed solution, and then the resulting seed solution is heated with an acidic silicic acid solution. Examples of the method include a method obtained by growing the silica particles in the seed solution by adding them below, an ion exchange resin method, a hydrolysis method of an organosilicon compound, and the like.

  The average particle diameter of the spherical particles is preferably in the range of 20 to 150 nm, and more preferably in the range of 50 to 100 nm. When the average particle diameter is less than 20 nm, the particles are likely to aggregate, and it is difficult to obtain a sufficient polishing effect. On the other hand, if the average particle diameter exceeds 150 nm, the spherical particles may be too large to reduce the polishing rate, or scratches (scratches) may occur on the polished surface.

Non-spherical particle The non-spherical particle in the present invention means an amorphous particle which does not correspond to the spherical particle having a sphericity of 0.9 or more and 1.0 or less. The shape of the non-spherical particles means that they are not substantially spherical, and there are various forms such as needles, columns, beads, rods, plates, lumps, fibers, spindles, etc. There are many things.
Methods for producing non-spherical particles are known. For example, in the case of silica particles, there is a method of neutralizing an alkali silicate with an acid, washing the produced silica hydrogel, and growing it by peptization by heat. In this case, sodium silicate marketed under the names of sodium silicate, potassium silicate, lithium silicate, quaternary ammonium silicate, No. 1 water glass, No. 2 water glass, No. 3 water glass, etc. It can be used. As the neutralizing acid, hydrochloric acid, sulfuric acid, nitric acid, organic acid, or the like is used. The alkali silicate and the acid are simultaneously added to the initial pure water so that the silica concentration at the time of neutralization is in the range of 3 to 10% while maintaining an appropriate temperature and stirring conditions. The production temperature condition of the silica hydrogel is 10 to 60 ° C., and the pH is preferably 3 to 8, particularly 4 to 7. The heating temperature range for peptization is preferably 60 to 98 ° C.

In addition to the above production method, a water-soluble Ca salt and / or Mg salt-containing aqueous solution containing 1 to 6% by weight of SiO ₂ and having a pH of _{2 to} 4 in an active silicic acid is added to Ca ₂ and CaO, MgO As a weight ratio of 1500 to 3500 ppm, the resulting aqueous solution is mixed with an alkali metal hydroxide, a water-soluble organic base or a water-soluble silicate thereof in an SiO ₂ / M ₂ O molar ratio of 20 to 200. A method is known in which the amount is mixed and heated at 60 to 150 ° C. for 0.5 to 40 hours. According to this method, an elongated shape having a uniform thickness and an extension in only one plane is known. Amorphous colloidal silica particles are obtained.

In addition, as described in JP-A-4-187512, (a) a silicate solution is added to an alkali metal silicate aqueous solution of 0.05 to 5.0 wt% as SiO ₂ , and the mixed solution SiO ₂ / M ₂ O (molar ratio, M is an alkali metal or quaternary ammonium) process 30 to 60; the previous (b) silicic acid solution addition step, during the addition step or after the addition step, Ca, Mg (1) adding one or more metal compounds selected from Al, Ti, Cu, rare earth metals, etc .; (c) maintaining the mixed solution at an arbitrary temperature of 60≡ or more for a predetermined time; and ( d) An elongated silica sol can also be obtained through a step of adding a silicic acid solution to the reaction solution again to adjust the SiO ₂ / M ₂ O (molar ratio) in the reaction solution to 60 to 100.

  The particle diameter of the non-spherical particles is preferably 5 to 100 nm, more preferably 10 to 50 nm. When the average particle diameter is less than 5 nm, the particles are easily aggregated, and it is difficult to obtain a sufficient polishing effect. On the other hand, if the average particle diameter exceeds 100 nm, the non-spherical particles may be too large and the polishing rate may decrease, or scratches (scratches) may occur on the polished surface.

Polishing composition The polishing composition of the present invention is obtained by dispersing the spherical particles and the non-spherical particles in an aqueous dispersion medium, and the weight ratio of the spherical particles to the non-spherical particles is 2/98 to 35/65. It is in the range. When the weight ratio of the spherical particles to the non-spherical particles is out of this range, the effect of maintaining a high level of polishing rate decreases. A more preferred weight ratio is 4/96 to 20/80.
In addition, as the particle size distribution of the colloidal particles of the polishing composition, those having a narrow distribution and uniform particle size are advantageous in achieving the above-described effects.

When the polishing composition of the present invention comprises silica particles, the polishing silica composition is obtained by mixing the aqueous silica sol containing the spherical particles and the aqueous silica sol containing the non-spherical particles. The mixing step of the silica sol is performed in a device with a stirrer under a temperature condition of 5 to 40 ° C. as much as possible.
As the aqueous dispersion medium, in addition to the aqueous dispersion medium, alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, and mixed solvents of water-soluble organic solvents such as ethers, esters, and ketones and water are used. The

  The concentration of the solid content of the spherical particles and the non-spherical particles in the polishing composition is usually 2 to 50% by weight, preferably 5 to 30% by weight. When the concentration is less than 2% by weight, the concentration of polishing particles may be too low to obtain a sufficient polishing rate. When the concentration exceeds 50% by weight, the stability of the abrasive becomes insufficient, and a dried product may be generated and adhered in the step of supplying the abrasive, which may cause scratches.

In general, the polishing composition of the present invention preferably has a pH in the range of 8 to 11.5, and more preferably pH 9 to 11 is recommended. When the pH is high, the silica particles are easily dissolved and aggregated. When the pH is low, the potential of the silica particles in the silica sol is lowered, and aggregation is likely to occur due to collision. The pH of the polishing composition can be adjusted using an acid or a base.
Further, when the polishing composition of the present invention is used as an abrasive such as a semiconductor wafer, it is necessary to remove impurities derived from the polishing composition, particularly basic impurities, and usually the basic impurities The amount of is preferably 100 ppm or less with respect to SiO ₂ .

  In order to improve the metal polishing rate, the polishing composition of the present invention may further contain hydrogen peroxide, peracetic acid, urea peroxide, or a mixture thereof depending on the type of material to be polished. Can be used. In addition, in order to adjust the polishing rate of multiple kinds of materials to be polished, acids such as sulfuric acid, nitric acid, phosphoric acid and hydrofluoric acid, or sodium salts, potassium salts, ammonium salts and mixtures of these acids are added. Can be used. As other additives that can be added, for example, imidazole, benzotriazole, benzothiazole, and the like can be used to form a passive layer or dissolution inhibiting layer on the surface of the metal polishing material to prevent erosion of the substrate. . In addition, complex forming materials such as citric acid, lactic acid, acetic acid, and oxalic acid can be used to disturb the passive layer. In order to improve the dispersibility and stability of the abrasive slurry, a cationic, anionic, nonionic or amphoteric surfactant can be appropriately selected and added. Further, when the material to be polished is a silica oxide film or the like, the polishing rate can be increased by adding an alkali metal silicate aqueous solution.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. First, preparation of a silica sol constituting the polishing composition of the present invention, a method for measuring physical properties, and a polishing test method will be described.

Preparation of silica sol (1) Silica sol F (non-spherical particles)
3 Gosui glass (Si0 ₂ concentration 24.0 wt%) silica gel obtained by adding 131g of a 5 wt% sulfuric acid 511g was washed with pure water, after addition of 15 wt% ammonia, heated to a predetermined temperature Silica sol F was obtained by ultraconcentrating 3 wt% silica sol in which the alkaline solution obtained by aging was dispersed to 12 wt%, and then concentrating to 20 wt% silica using a rotary evaporator. An electron micrograph (250,000 times) of silica sol F is shown in FIG.
According to the measurement method described below, silica sol F had an average particle size of 17 nm and a sphericity of 0.52.

(2) Silica sol B (spherical particles)
Si0 ₂ concentration of 24.0 wt%, Si0 of ₂ / Na ₂ O molar ratio 3.1 silicic oxygen - da solution was mixed with ion-exchanged water, Si0 ₂ concentration of 5.2 wt% dilute silicic oxygen - da A solution was prepared. This solution was passed through a column packed with a hydrogen cation exchange resin layer (Diaion 5K-1B, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) to prepare an acidic silicate solution. Si0 ₂ concentration of the acidic silicic acid solution is 5.0 wt%, pH was 2.7. The Na ₂ O concentration was 0.1% by weight or less in terms of solid content silica.

Reflux condenser, stirrer, a stainless steel container of 10L equipped with a temperature sensing device, pure water 650g and 3 Gosui glass (Si0 ₂ concentration 24.0 wt%) 40 g was added, further manufactured silica sol (Catalysts & Chemicals Industries Co., Then, 70 g of cataloid SI-50 (48% by weight) was added, and a seed solution was prepared by heating up to 98 ° C. 9750 g of the acidic silicic acid solution was added to this seed solution over 14 hours. After aging and cooling at the same temperature for 1 hour, the obtained 5 wt% silica sol was ultraconcentrated to 12 wt%, and then 5 wt% NaOH and 0.1 wt% HCl were added, and then the mixture was added to the rotary evaporator. The silica concentration was 40% by weight to obtain silica sol B. An electron micrograph (250,000 times) of the silica sol B is shown in Fig. 3. The average particle size of the silica sol B is 45 nm, and the sphericity. Was 0.94.

(3) Silica sol C (spherical particles)
Silica sol (concentration 40 wt%, average particle size 40 nm) is mixed with sodium silicate solution (SiO ₂ concentration 24 wt%) and pure water to obtain seed solution (total SiO ₂ concentration 4.0 wt%, SiO ₂ / Na ₂ O molar ratio 15.0) was prepared.
Into a 10 L stainless steel container equipped with a reflux device, a stirrer, and a temperature detector, pure water 1990 g and No. 3 water glass (SiO ₂ concentration 24.0 wt%) 50 g were added, and silica sol (manufactured by Catalyst Kasei Kogyo Co., Ltd.) Then, 130 g of cataloid SI-45P (40 wt%) was added, and the temperature was raised to 98 ° C. to prepare a seed solution, and 7820 g of the acidic silicic acid solution was added to the seed solution over 18 hours. After aging and cooling at the same temperature for 1 hour, the obtained 5 wt% silica sol was ultraconcentrated to 12 wt%, and then 5 wt% NaOH and 0.1 wt% HCl were added, and then the mixture was added to the rotary evaporator. The silica sol C was concentrated to obtain a silica sol C. The silica sol C had an average particle size of 80 nm and a sphericity of 0.95.

Method of measuring physical properties (1) Specific surface area The specific surface area of silica fine particles was determined by using a specific surface area measuring device (manufactured by Yuasa Ionics, "Multisorb 12" for a sample obtained by drying a silica sol with a freeze dryer and then drying at 110 ° C for 20 hours. )) And the nitrogen adsorption method (BET method).
(2) Average particle diameter The average particle diameter of the silica fine particles was measured by a dynamic light scattering method using a particle size distribution measuring apparatus (manufactured by Particle Sizing Systems, "NICOMP MODEL 380").
(3) Sphericity Particles are photographed with a scanning electron microscope (JEOL Ltd., JIS-5300 type), and each of 10 arbitrary particles has a maximum diameter (DL) and a short diameter perpendicular thereto. (DS) was determined, and the average value of the ratio (DS / DL) was determined as sphericity.

Polishing test method Prepare a 29 mm square lithium tantalate substrate for polishing test, set it on a polishing machine (NF300, manufactured by Nano Factor Co., Ltd.), load substrate 0.12 MPa, table rotation speed 30 rpm, spindle A sacrificial layer (thickness: 0.2 μm) on the insulating film at a rate of 70 ml / min at a speed of 60 rpm with each polishing composition described later (all adjusted to pH 11 by adding a 10% aqueous solution of sodium hydroxide). Polishing was performed until there was no more. The polishing time at this time was 120 minutes.
Measurement Method of Basic Impurity An inorganic anion concentration was measured using an ion chromatograph (model number: DX-AQ) manufactured by DIONEX.

350 parts of silica sol F composed of non-spherical particles (average particle diameter 17 nm, solid content 20% by weight), 75 parts of silica sol C composed of spherical particles (average particle diameter 80 nm, solid content 40% by weight), and pure water 75 A polishing composition (solid content concentration 20% by weight) having a weight ratio of spherical particles to non-spherical particles of 30/70 was prepared. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .
The polishing test was carried out using this polishing composition. The results of measuring the polishing rate are shown in Table 1. In Table 1, the “polishing rate ratio” is the polishing rate of the polishing composition consisting only of silica sol C (polishing rate after 30 minutes in Comparative Example 2 described later). Relative value when 0 is shown.

A polishing composition comprising 450 parts by weight of silica sol F, 25 parts by weight of silica sol C and 20 parts by weight of pure water and having a weight ratio of spherical particles to non-spherical particles of 10/90 (solid content concentration 20% by weight) ) And a polishing test was conducted in the same manner as in Example 1. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

460 parts by weight of silica sol F and 20 parts by weight of silica sol C were blended to prepare a polishing composition (solid content concentration 20% by weight) in which the weight ratio of spherical particles to non-spherical particles was 8/92. A polishing test was conducted in the same manner as in Example 1. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

475 parts by weight of silica sol F and 12.5 parts by weight of silica sol C are blended to prepare a polishing composition (solid content concentration 20% by weight) in which the weight ratio of spherical particles to non-spherical particles is 5/95. Then, a polishing test was conducted in the same manner as in Example 1. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

485 parts by weight of silica sol F and 7.5 parts by weight of silica sol C are blended to prepare a polishing composition (solid content concentration 20% by weight) in which the weight ratio of spherical particles to non-spherical particles is 3/97. Then, a polishing test was conducted in the same manner as in Example 1. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

Comparative Example 1

A polishing composition comprising 300 parts by weight of silica sol F, 100 parts by weight of silica sol C, and 100 g of pure water, and the weight ratio of spherical particles to non-spherical particles is 40/60 (solid content concentration 20% by weight) Was prepared. Using this polishing composition, a polishing test was performed in the same manner as in Example 1. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

Comparative Example 2

A polishing test was conducted in the same manner as in Example 1 on a polishing composition (solid content concentration 20% by weight) composed of 250 parts by weight of silica sol C and 250 parts by weight of pure water. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

Comparative Example 3

A polishing test was carried out in the same manner as in Example 1 for the polishing composition consisting of only silica sol F (solid content concentration 20% by weight). The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

Comparative Example 4

A polishing test was conducted in the same manner as in Example 1 on a polishing composition (solid content concentration 20% by weight) composed of 250 parts by weight of silica sol B and 250 parts by weight of pure water. The concentration of basic impurities in the polishing composition was less than 100ppm against SiO _2.

A polishing composition was prepared in the same manner except that silica sol B (45 nm, solid content 40% by weight) was used instead of silica sol C of Example 1, and a polishing test was performed. The concentration of basic impurities in this polishing composition was less than 100 ppm with respect to SiO ₂ .

[Table 1]
Example NO Silica Sol Type (parts by weight ) Polishing Rate Ratio
Spherical particles Non-spherical particles 30 minutes later 60 minutes later 120 minutes later Example 1 C (30) F (70) 1.02 0.84 0.77
Example 2 C (10) F (90) 1.34 1.45 1.47
Example 3 C (8) F (92) 1.62 1.51 1.59
Example 4 C (5) F (95) 1.77 1.56 1.44
Example 5 C (3) F (97) 1.66 1.56 1.47
Example 6 B (30) F (70) 1.01 0.75 0.54
Comparative Example 1 C (40) F (60) 0.91 0.68 0.42
Comparative Example 2 C (100) -1.00 0.70 0.43
Comparative Example 3-F (100) 0.89 0.65 0.41
Comparative Example 4 B (100)-0.62 0.42 0.35

  The development of a polishing composition (abrasive) with a high polishing rate as in the present invention has been achieved by improving the productivity of semiconductor interlayer insulating films, lithium tantalate substrates, silicon substrates, substrates with oxide films, gem compound semiconductors, etc. Greatly contributes. In addition, improvement in productivity is also expected in metal (SUS), display glass, liquid crystal glass, and the like.

It is sectional drawing of a to-be-polished material which shows the state before grinding | polishing by the conventional CMP (A) and after grinding | polishing (B). 2 is an electron micrograph (250,000 times) showing the particle structure of silica sol F. FIG. 2 is an electron micrograph (250,000 times) showing the particle structure of silica sol B. FIG.

Claims (6)

A polishing composition in which spherical particles having a sphericity in a range of 0.9 or more and 1.0 or less and non-spherical particles not corresponding to the spherical particles are dispersed in an aqueous dispersion medium. A polishing composition wherein the weight ratio of spherical particles to particles is in the range of 2/98 to 35/65.
The polishing composition according to claim 1, wherein the spherical particles and the non-spherical particles are silica particles.
The polishing composition according to claim 1 or 2, wherein the spherical particles have an average particle diameter in the range of 20 to 150 nm, and the non-spherical particles have an average particle diameter in the range of 5 to 100 nm.
The polishing composition according to claim 1, 2 or 3, wherein the polishing composition has a pH of 8 to 11.5.
The polishing composition according to claim 1, 2, 3, or 4, wherein the non-spherical particles are obtained by neutralizing an alkali silicate with an acid, washing the produced silica hydrogel, and growing by heat peptization. object.
The polishing composition according to claim 1, 2, 3, 4 or 5, wherein the amount of basic impurities contained in the polishing composition is 100 ppm or less with respect to SiO ₂ .