JP5403957B2 - Polishing liquid composition - Google Patents

Description

  The present invention relates to a polishing liquid composition used in chemical mechanical polishing (CMP) performed in a manufacturing process of a semiconductor device or the like, or a polishing process performed in a manufacturing process of a precision glass product or a display related product. . The present invention also relates to a polishing method using the above polishing composition, a method for producing a substrate for precision parts such as a glass substrate and a semiconductor device substrate.

  Synthetic quartz used as an oxide film (for example, silicon oxide film), a glass substrate (for example, a chemically tempered glass substrate such as an aluminosilicate glass substrate, a crystallized glass substrate such as a glass ceramic substrate, or a photomask substrate constituting a semiconductor device. As an abrasive composition used in the manufacturing process of a glass substrate) or a liquid crystal display panel or the like, an abrasive containing cerium oxide as a main component has been conventionally known (for example, see Patent Document 1).

Further, in order to solve the problem of generation of scratches and dust that occurs when polishing is performed using an abrasive composition containing cerium oxide particles as an abrasive, an average of secondary particles is used instead of cerium oxide particles. An abrasive containing a composite oxide particle having a particle size of 5 μm or less as an abrasive is known (see Patent Document 2). The oxidation number of cerium in a cerium compound (for example, CeCl ₃ ) that is a raw material of the composite oxide particles is 3, and the oxidation number of zirconium in the zirconium compound (ZrOCl ₂ ) is 4. The composite oxide particles are prepared as follows.

A cerium compound and a zirconium compound are reacted with ammonia in an aqueous solution to form a water-insoluble compound containing cerium and zirconium, and then a coprecipitate is obtained through oxidation treatment, filtration, and centrifugation. The coprecipitate is repeatedly washed with ultrapure water or the like, dried, and then heat-treated in an oven having an atmospheric temperature of 300 ° C. or higher, whereby composite oxide particles are obtained.
JP-A-6-216093 JP 2001-348563 A

  However, in polishing using these polishing liquid compositions, a sufficient polishing rate cannot be ensured, and scratches cannot be reduced.

  In the present invention, a polishing composition that suppresses the occurrence of scratches and enables polishing of an object to be polished at high speed, a polishing method using the same, and manufacture of a substrate for precision parts such as a glass substrate or a semiconductor device substrate. Provide a method.

The polishing liquid composition of the present invention is a polishing liquid composition comprising composite oxide particles containing cerium and zirconium, a dispersant, and an aqueous medium,
The crystallite size of the composite oxide particles is 10 to 50 nm,
In the powder X-ray diffraction spectrum of the composite oxide particles obtained by irradiating with CuKα1 rays (λ = 0.154050 nm),
A peak (first peak) having a peak within a diffraction angle 2θ (θ is a black angle) region 28.68 to 29.11 °,
A peak (second peak) having an apex within a diffraction angle 2θ region of 33.23 to 33.79 °,
A peak having a peak within the diffraction angle 2θ region of 47.71 to 48.53 ° (third peak) and a peak having a peak within the diffraction angle 2θ region of 56.61 to 57.60 ° (fourth peak). Each exists,
The half width of the first peak is 0.3 ° to 0.8 °;
When at least one of peak a1 derived from cerium oxide and peak a2 derived from zirconium oxide is present in the powder X-ray diffraction spectrum,
The peak heights of the peaks a1 and a2 are 6.0% or less of the peak height of the first peak. However, the apex of the peak a1 exists in a diffraction angle 2θ region of 28.40 to 28.59 °, and the apex of the peak a2 exists in a diffraction angle 2θ region of 29.69 to 31.60 °.

Moreover, the polishing composition of the present invention comprises:
A polishing liquid composition comprising composite oxide particles containing cerium and zirconium, a dispersant, and an aqueous medium,
The composite oxide particles are prepared by mixing a solution containing a cerium compound having an oxidation number of 4 and a zirconium compound having an oxidation number of 4 with a precipitant, whereby the cerium compound and the zirconium compound are mixed. Hydrolysis, separating the resulting precipitate, then
Composite oxide particles obtained by firing in an atmosphere of 800 to 1500 ° C. and pulverizing the obtained fired product.

  In the polishing method of the present invention, the polishing composition of the present invention is supplied between a polishing target substrate and a polishing pad, and the polishing pad is polished with the polishing target substrate in contact with the polishing pad. A step of polishing the substrate to be polished by moving the substrate relative to the target substrate;

  The manufacturing method of the substrate for precision parts of the present invention includes a polishing step of polishing at least one main surface of both main surfaces of the substrate to be polished using the polishing composition of the present invention.

According to the present invention, a polishing liquid composition that suppresses the occurrence of scratches and can polish a substrate to be polished at a higher speed, a polishing method using the same, and a precision substrate such as a glass substrate or a semiconductor device substrate. A method for manufacturing a substrate can be provided.

  Conventional composite oxide particles in which cerium oxide and zirconium oxide are in solid solution can be polished at high speed, but the solid solution of cerium oxide and zirconium oxide is not sufficient, and scratches are likely to occur. Although the cause of the occurrence of scratch is not clear, it is presumed that it is caused by zirconium oxide by-produced in addition to the composite oxide particles.

  In the process of producing composite oxide particles containing cerium and zirconium, the present inventor calcinated a precipitate in a state where the cerium compound and the zirconium compound were highly mixed, so that cerium and zirconium were highly dissolved. It has been found that polycrystalline composite oxide particles can be obtained. By using such composite oxide particles as abrasive grains, both high-speed polishing and scratch reduction can be achieved. In particular, scratching is remarkably reduced by firing a precipitate in a state in which a cerium compound and a zirconium compound are highly mixed at a low temperature. The reason why the scratch is remarkably reduced is not clear, but when the precipitate is fired at a low temperature, composite oxide particles having a small crystallite size are obtained, and the composite oxide particles are formed by the load applied to the abrasive during polishing. It is estimated that it will collapse and scratch will be significantly reduced.

[Composite oxide particles]
The composite oxide particles are represented by the following composition formula, for example.
Ce _X Zr _1-X O ₂
However, x is a conditional expression 0 <x <1, preferably 0.50 <x <0.97, more preferably 0.60 <x <0.93, and still more preferably 0.70 <x <0.90. Even more preferably, the number satisfies 0.70 <x <0.80.

  In the composite oxide particles, cerium oxide and zirconium oxide are uniformly dissolved to form one solid phase, and this composite oxide particle is X-ray (Cu-Kα1 line, λ = 0.154050 nm). ) The following peaks are observed in the spectrum obtained by analyzing by the diffraction method.

That is, in the spectrum, at least a peak having a peak within a diffraction angle 2θ region of 28.68 to 29.11 ° (first peak) and a peak having a peak within a diffraction angle 2θ region of 33.23 to 33.79 °. (Second peak), a peak with a peak in the diffraction angle 2θ region 47.71 to 48.53 ° (third peak), and a peak with a peak in the diffraction angle 2θ region 56.61 to 57.60 ° (4th peak) is observed.

  From the viewpoint of improving the polishing rate, the composite oxide particles have a peak (first peak) having a peak within at least a diffraction angle 2θ region of 28.75 to 29.00 ° in the spectrum, and a diffraction angle 2θ region of 33.30. Peak having a vertex within ˜33.70 ° (second peak), peak having a vertex within 47.80 to 48.40 ° (third peak), and diffraction angle 2θ region 56.75 It is preferable that a peak (fourth peak) having a vertex within ˜57.45 ° is observed, and further, a peak having a vertex within a diffraction angle 2θ region of 28.80 to 28.95 ° (first peak). Peak), peak with a peak in the diffraction angle 2θ region 33.40 to 33.60 ° (second peak), peak with a peak in the diffraction angle 2θ region 47.90 to 48.25 ° (third peak) , And diffraction angle 2θ region 56.90 ~ More preferably the one in which peaks at the vertex (fourth peak) is observed in 7.30 in °.

  The area of the second peak is 10 to 50% of the area of the first peak, the area of the third peak is 35 to 75% of the area of the first peak, and the area of the fourth peak is 20 of the area of the first peak. It is preferable that it is -65%. From the viewpoint of improving the polishing rate, the area of the second peak is 15 to 45% of the area of the first peak, the area of the third peak is 40 to 70% of the area of the first peak, and the area of the fourth peak is More preferably, it is 25-60% of the area of the first peak, the area of the second peak is 20-40% of the area of the first peak, and the area of the third peak is 45-45 of the area of the first peak. The area of 65% and the fourth peak is more preferably 30 to 55% of the area of the first peak.

There may be a case where at least one of the peak a ₁ derived from cerium oxide and the peak a ₂ derived from zirconium oxide exists in the spectrum. In this case, the peak heights of the peaks a ₁ and a ₂ are both 6.0% or less of the height of the peak of the first peak, preferably 3.0% or less, more preferably from the viewpoint of scratch reduction. Is 1.0% or less, more preferably 0%.

The diffraction angle 2θ region where the apex of the peak a ₁ exists is 28.40 ° to 28.59 °, and the diffraction angle 2θ region where the apex of the peak a ₂ exists is 29.69 ° to 31.60 °. These values for the 2θ region are based on values for cerium oxide and zirconium oxide in the international diffraction data ICDD (International Center for Diffraction Data). Specifically, the diffraction angle 2θ region 28.40 to 28.59 ° where the peak of peak a ₁ exists is a value for cubic cerium oxide. The 2θ region 29.69 to 31.60 ° where the peak of peak a ₂ is present is 2θ (29.69 °) of tetragonal zirconium oxide and 2θ (31.60 °) of monoclinic zirconium oxide. ).

  The half width of the first peak is 0.3 ° to 0.8 °, but from the viewpoint of improving the polishing rate and reducing scratches, 0.35 ° to 0.7 ° is preferable, and 0.4 ° to 0.6 ° is more preferable, and 0.42 ° to 0.5 ° is more preferable. This half-value width correlates with the crystallite size as shown in the Scherrer equation. The full width at half maximum decreases as the crystallite size increases due to crystal growth. The half width of the first peak adjusts the atomic molar ratio of Ce and Zr in the composite oxide particles and the firing temperature of the precipitate obtained by hydrolyzing the cerium compound and the zirconium compound in the production process. Can be controlled. For example, when the firing temperature is increased, the crystallite size is increased due to crystal growth, and when the firing temperature is decreased, the crystallite size is decreased.

In the composite oxide particles of the present embodiment, as described later, cerium oxide is derived from a cerium compound having an oxidation number of 4, and zirconium oxide is derived from a zirconium compound having an oxidation number of 4, It is considered that one solid phase in which cerium oxide and zirconium oxide are uniformly dissolved is formed, and the X-ray diffraction spectrum is observed. When the cerium oxide in the composite oxide particles is derived from a cerium compound having an oxidation number of 3, like the composite oxide particles contained in the polishing liquid composition described in Patent Document 2, cerium oxide and zirconium oxide are Formation of one solid phase that is uniformly dissolved is not sufficiently performed, and at least one of a peak a ₁ derived from cerium oxide and a peak a ₂ derived from zirconium oxide is observed. The peak apex height is more than 6.0% of the first peak apex height.

  From the viewpoint of improving the polishing rate, the molar ratio of atoms (Ce / Zr) in the composite oxide particles is preferably (99/1) to (40/60), and (95/5) to (50 / 50), more preferably (93/7) to (60/40), and even more preferably (90/10) to (70/30).

The atomic ratio x of Ce to Zr in the composite oxide (Ce _X Zr _{1 -X} O ₂ ) particles is:
From the viewpoint of reducing scratches, it is preferably 0.60 to 0.93, more preferably 0.65 to 0.90, and still more preferably 0.70 to 0.90.

  From the viewpoint of improving the polishing rate, the volume median diameter (D50) of the composite oxide particles in the polishing composition is preferably 30 nm or more, more preferably 50 nm or more, still more preferably 80 nm or more, and still more preferably. 100 nm or more, still more preferably 120 nm or more. Further, D50 is preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 400 nm or less, and even more preferably 300 nm or less, from the viewpoint of improving the dispersion stability of the composite oxide particles in the polishing composition. Even more preferably, it is 250 nm or less. Therefore, the volume median diameter (D50) of the composite oxide particles is preferably 30 to 1000 nm, more preferably 50 to 500 nm, still more preferably 80 to 400 nm, still more preferably 100 to 300 nm, and even more preferably 120 to 250 nm.

  Here, the volume median diameter (D50) means a particle diameter at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle diameter. The volume median diameter (D50) is obtained as a volume-based median diameter measured with a laser diffraction / scattering particle size distribution meter (trade name LA-920, manufactured by Horiba, Ltd.).

  From the viewpoint of improving the polishing rate, the average primary particle size of the composite oxide particles is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, and even more preferably 25 nm or less. The average primary particle diameter of the composite oxide particles is preferably 100 nm or less, more preferably 80 nm or less, and still more preferably 60 nm or less, from the viewpoint of improving the mirror surface state of the polishing surface obtained by polishing the polishing object. More preferably, it is 40 nm or less, and still more preferably 35 nm or less. Therefore, the average primary particle diameter of the composite oxide particles is preferably 10 to 100 nm, more preferably 15 to 80 nm, still more preferably 20 to 60 nm, still more preferably 25 to 40 nm, and even more preferably 25 to 35 nm. It is.

Here, the average primary particle size (nm) means the particle size (true sphere conversion) calculated by the following formula using the specific surface area S (m ² / g) calculated by the BET (nitrogen adsorption) method. .
Average primary particle diameter (nm) = 820 / S

From the viewpoint of compatibility between high-speed polishing and scratch reduction, the specific surface area of the composite oxide particles is preferably 15 to 100 m ² / g, more preferably 17 to 70 m ² / g, and still more preferably 19 to 60 m ² / g. More preferably, it is 20-45 m < ² > / g, More preferably, it is 22-35 m < ² > / g.

  The complex oxide particle is a polycrystal composed of a plurality of crystallites. The crystallite size of the crystallites constituting the composite oxide particles in the polishing composition is 10 to 50 nm, but is preferably 15 nm or more, more preferably 20 nm or more from the viewpoint of further increasing the polishing rate. . The crystallite size constituting the composite oxide particles is preferably 45 nm or less, more preferably 40 nm or less, and further preferably 35 nm or less, and still more preferably, from the viewpoint of enabling more effective reduction of scratches. Is 28 nm or less. Therefore, the crystallite size of the composite oxide particles is preferably 15 to 45 nm, more preferably 20 to 40 nm, still more preferably 20 to 35 nm, and still more preferably 20 to 28 nm.

  From the viewpoint of improving the polishing rate, the content of the composite oxide particles in the polishing composition is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, and further preferably 0.4% by weight. Or more, and more preferably 0.5% by weight or more. Further, the content of the composite oxide particles is preferably 8% by weight or less, more preferably 5% by weight or less, and further preferably 4% by weight or less, from the viewpoint of improving dispersion stability and reducing the cost. More preferably 3% by weight or less. Accordingly, the content of the composite oxide particles is preferably 0.1 to 8% by weight, more preferably 0.2 to 5% by weight, still more preferably 0.4 to 4% by weight, and still more preferably 0.5. ~ 3 wt%.

  Next, an example of a method for producing composite oxide particles will be described.

  The composite oxide particles include a solution containing a cerium compound having an oxidation number of 4 (hereinafter also referred to as a cerium (IV) compound) and a zirconium compound having an oxidation number of 4 (hereinafter also referred to as a zirconium (IV) compound). The cerium (IV) compound and the zirconium (IV) compound are hydrolyzed by mixing with a precipitant, the resulting precipitate is separated, and then calcined at a predetermined temperature. It can be obtained by grinding.

  The solution containing a cerium (IV) compound and a zirconium (IV) compound is prepared by, for example, dissolving a water-soluble cerium (IV) compound such as cerium nitrate and a water-soluble zirconium (IV) compound such as zirconium nitrate. It may be prepared by mixing in a solvent such as.

  If a precipitant (base solution) is added to the solution containing the cerium (IV) compound and the zirconium (IV) compound, the cerium (IV) compound and the zirconium (IV) compound are hydrolyzed, and the precipitate is formed. Generated. It is preferable to add a precipitant while stirring a solution containing a cerium (IV) compound and a zirconium (IV) compound. As the precipitating agent, ammonia solution; alkaline hydroxide solution such as sodium hydroxide solution or potassium hydroxide solution; carbonate solution of sodium, potassium or ammonia; bicarbonate solution or the like is used. The precipitant is preferably an aqueous solution of ammonia, sodium hydroxide or potassium hydroxide, more preferably an aqueous ammonia solution. The normality of the precipitating agent is preferably about 1 to 5N, and more preferably about 2 to 3N.

  The pH of the supernatant obtained by adding a precipitant to a solution containing a cerium (IV) compound and a zirconium (IV) compound is a complex oxide particle in which cerium oxide and zirconium oxide are in a highly solid solution state. From the viewpoint of obtaining the above, 7 to 11 is preferable, and 7.5 to 9.5 is more preferable.

  The mixing time of the solution containing the cerium (IV) compound and the zirconium (IV) compound and the precipitating agent is not particularly limited, but is preferably 15 minutes or more, and more preferably 30 minutes or more. The reaction between the solution containing the cerium (IV) compound and the zirconium (IV) compound and the precipitating agent can be performed at any suitable temperature such as room temperature. The precipitate produced by mixing a solution containing a cerium (IV) compound and a zirconium (IV) compound and a precipitating agent is subjected to normal solid / liquid separation such as decantation, drying, filtration and / or centrifugation. Separable from mother liquor by technology. The resulting precipitate is then washed with water or the like.

  The cerium (IV) compound in the solution is preferably simply contained in a state where the cerium (IV) compound is added to the aqueous medium, but the cerium compound containing cerium having an oxidation number of 3 is electrolyzed in the aqueous medium. By oxidation, trivalent cerium may be converted to tetravalent cerium. The cerium (IV) compound is preferably contained in an amount of 85% by weight or more, more preferably 87% by weight or more, further preferably 90% by weight or more, and 95% by weight in the total amount of the cerium compound. Even more preferably, it is contained.

  Specific examples of the cerium (IV) compound include water-soluble salts such as cerium sulfate (IV), tetraammonium cerium sulfate (IV), and diammonium cerium nitrate (IV). The cerium salt having an oxidation number of 4 is more easily hydrolyzed than the cerium salt having an oxidation number of 3, and from the viewpoint of hydrolysis rate, a zirconium (IV) compound (for example, This is because it is suitable for simultaneous hydrolysis with a zirconium salt having an oxidation number of 4).

  Zirconium (IV) compounds contained in the solution include zirconium oxychloride (zirconyl chloride), zirconium oxysulfate (zirconyl sulfate), zirconium oxyacetate (zirconyl acetate), zirconium oxynitrate (zirconyl nitrate), zirconium chloride, zirconium nitrate Water-soluble zirconium (IV) salts such as zirconium acetate and zirconium sulfate.

As described above, when the oxidation number of cerium and zirconium in the solution is 4 and the pH of the solution is increased by adding the base solution as a precipitant to the solution, the cerium (IV) compound and zirconium (IV ) The compound is hydrolyzed in approximately the same pH region, and cerium hydroxide and zirconium hydroxide precipitate almost simultaneously, resulting in a highly mixed precipitate with each other. By heat-treating this precipitate, a portion in which cerium oxide and zirconium oxide are uniformly dissolved to form one solid phase is generated in the precipitate. If the oxidation number of cerium is 3, the pH range in which the cerium (III) compound and the zirconium (IV) compound are hydrolyzed and the hydroxide precipitates is different, so that a precipitate in which the mixing state of both is insufficient is obtained. It is done. When this precipitate is heat-treated, a portion where cerium oxide or zirconium oxide is separated is generated.

  When the total amount of oxide of cerium element and the amount of oxide of zirconium element contained in the solution containing the cerium compound and the zirconium compound is 100% by weight, the amount of oxide of cerium element is 7 to 99% by weight. %, Preferably 20 to 98% by weight, more preferably 50 to 96% by weight. The oxide equivalent amount of zirconium element is preferably 1 to 93% by weight, more preferably 2 to 80% by weight, and further preferably 4 to 50% by weight.

  The firing temperature of the precipitate is required to be 800 to 1500 ° C. from the viewpoint of ensuring a high polishing rate and a scratch reduction effect, but is preferably 850 to 1300 ° C., more preferably 900 to 1200 ° C. More preferably, it is 1000-1100 degreeC. The firing time is usually preferably 1 to 10 hours, more preferably 2 to 8 hours, and further preferably 3 to 7 hours. Firing can be performed using a heating means such as a continuous firing furnace. The firing temperature is the temperature of the particle surface and is equal to the ambient temperature in the continuous firing furnace.

The specific surface area calculated by the BET (nitrogen adsorption) method of the fired product obtained by firing the precipitate is preferably 5 to 100 m ² / g from the viewpoint of obtaining composite oxide particles exhibiting suitable disintegration properties. More preferably, it is 10-50 m < ² > / g, More preferably, it is 12-40 m < ² > / g, More preferably, it is 15-30 m < ² > / g.

  In a spectrum obtained by analyzing the fired product by an X-ray (Cu-Kα1 ray, λ = 0.154050 nm) diffraction method, a diffraction angle 2θ (θ is a black angle) in a region 28.68 to 29.11 ° From the viewpoint of improving the polishing rate, the half width of the peak having an apex is preferably 0.2 ° to 0.8 °, more preferably 0.25 ° to 0.7 °, and 0.3 ° to 0.00. 6 ° is more preferable, and 0.35 ° to 0.5 ° is even more preferable.

  From the viewpoint of further increasing the polishing rate, the crystallite size of the crystallites constituting the fired product is preferably 10 nm or more, more preferably 15 nm or more, and further preferably 20 nm or more. The crystallite size constituting the fired product is preferably 100 nm or less, more preferably 50 nm or less, still more preferably 40 nm or less, and even more preferably 30 nm from the viewpoint of enabling more effective reduction of scratches. It is as follows. Therefore, the crystallite size constituting the fired product is preferably 10 to 100 nm, more preferably 15 to 50 nm, still more preferably 20 to 40 nm, and still more preferably 20 to 30 nm.

  The means for pulverizing the fired product is not particularly limited, and examples thereof include pulverizers such as a ball mill, a bead mill, and a vibration mill. The setting conditions of the pulverizing means may be appropriately set in order to form particles having a desired average particle size range or particles having a desired volume particle size range. Examples of the grinding media include zirconia balls.

[Aqueous medium]
Examples of the aqueous medium contained in the polishing liquid composition of the present embodiment include water, a mixed medium of water and a solvent, and the solvent includes a solvent that can be mixed with water (for example, alcohol such as ethanol). Is preferred. Among these, water is preferable as the aqueous medium, and ion-exchanged water is more preferable.

[Dispersant]
The dispersant contained in the polishing composition of this embodiment is preferably water-soluble. The water-soluble dispersant is preferably at least one selected from the group consisting of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an acrylic acid polymer. More preferably, the dispersant is at least one selected from the group consisting of an anionic surfactant, a nonionic surfactant, and an acrylic acid polymer. The dispersant is more preferably an acrylic acid polymer. The dispersant may be physically adsorbed on the surface of the composite oxide particle before being mixed with the aqueous medium, or may be chemically bonded to the surface of the composite oxide particle.

  Examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts.

  Examples of the anionic surfactant include fatty acid soaps, carboxylates such as alkyl ether carboxylates, sulfonates such as alkylbenzene sulfonates and alkylnaphthalene sulfonates, higher alcohol sulfates, alkyl ether sulfates. And sulfate ester salts such as alkyl phosphate esters and the like.

  Nonionic surfactants include, for example, ether types such as polyoxyethylene alkyl ether, ether ester types such as glycerin ester polyoxyethylene ether, ester types such as polyethylene glycol fatty acid ester, glycerin ester, and sorbitan ester. Can be mentioned.

  The acrylic acid polymer may be a homopolymer or a copolymer. The homopolymer preferably includes a homopolymer containing the structural unit (A) derived from the monomer (a) such as acrylic acid, a non-metallic salt of acrylic acid, or an acrylic ester. As the copolymer, preferably, the structural unit (A) derived from at least one monomer (a) selected from the group consisting of acrylic acid, a non-metallic salt of acrylic acid, and an acrylic ester, and the following monomer ( Each structural unit derived from at least two types of monomers (a) selected from the group consisting of a copolymer comprising the structural unit (B) derived from b), acrylic acid, a non-metallic salt of acrylic acid, and an acrylic ester Mention may be made of copolymers comprising (A).

  Examples of acrylic acid nonmetal salts include ammonium acrylate salts and amine acrylate salts. The acrylic acid polymer may contain one or more kinds of structural units derived from these non-acrylic acid metal salts.

  When the acrylic acid polymer is a copolymer, the structural unit (A) is contained in an amount exceeding 50 mol%, preferably exceeding 70 mol%, and exceeding 80 mol%. It is more preferable if it contains, and it is further more preferable if it contains exceeding 90 mol%.

  The monomer (b) is a monomer having a carboxylic acid (salt) group and having a polymerizable double bond, such as itaconic acid, itaconic anhydride, methacrylic acid, maleic acid, Maleic anhydride, fumaric acid, fumaric anhydride, citraconic acid, citraconic anhydride, glutaconic acid, vinyl acetic acid, allyl acetic acid, phosphinocarboxylic acid, α-haloacrylic acid, β-carboxylic acid, or salts thereof, methacrylic And alkyl methacrylates such as methyl acrylate, ethyl methacrylate, and octyl methacrylate.

  When the acrylic acid polymer is a salt, it can be obtained, for example, by polymerizing an acid acrylic monomer alone or copolymerizing with the monomer (b) and then neutralizing with a predetermined alkali. . Examples of the salt include an ammonium salt of a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid.

  From the viewpoint of improving dispersion stability, the acrylic acid polymer is preferably at least one selected from the group consisting of polyacrylic acid and ammonium polyacrylate, and more preferably ammonium polyacrylate.

  The weight average molecular weight of the acrylic acid polymer is preferably 500 to 50,000, more preferably 500 to 10,000, and further preferably 1,000 to 10,000 from the viewpoint of improving dispersion stability.

The weight average molecular weight is a value calculated based on a peak in a chromatogram obtained by applying a gel permeation chromatography (GPC) method under the following conditions.
Column: G4000PWXL + G2500PWXL (Tosoh Corporation)
Eluent: (0.2 M phosphate buffer) / (CH ₃ CN) = 9/1 (volume ratio)
Flow rate: 1.0 mL / min
Column temperature: 40 ° C
Detector: RI detector Standard material: Polyacrylic acid equivalent

  The content of the dispersant in the polishing composition is preferably 0.0005% by weight or more, more preferably 0.001% by weight or more, and still more preferably 0.002% by weight or more, from the viewpoint of improving dispersion stability. It is. The content of the dispersant in the polishing composition is preferably 0.5% by weight or less, more preferably 0.1% by weight or less, and still more preferably 0.05% by weight or less. Therefore, the content of the dispersant is preferably 0.0005 to 0.5% by weight, more preferably 0.001 to 0.1% by weight, and still more preferably 0.002 to 0.05% by weight.

  The content of each component described above is the content at the time of use, but the polishing composition of the present embodiment is stored and supplied in a concentrated state as long as the stability is not impaired. May be. In this case, it is preferable in that the production / transport cost can be reduced. The concentrate may be used after appropriately diluted with the above-mentioned aqueous medium as necessary.

  When the polishing liquid composition of the invention of this embodiment is the concentrated liquid, the content of the composite oxide particles is preferably 2% by weight or more, more preferably 3% by weight from the viewpoint of reducing production / transport costs. As mentioned above, More preferably, it is 5 weight% or more, More preferably, it is 10 weight% or more. Further, from the viewpoint of improving dispersion stability, the content of the composite oxide particles is preferably 50% by weight or less, more preferably 40% by weight or less, and still more preferably 30% by weight or less. Therefore, the content of the composite oxide particles is preferably 2 to 50% by weight, more preferably 3 to 40% by weight, still more preferably 5 to 30% by weight, and still more preferably 10 to 30% by weight.

[Water-soluble organic compounds]
The polishing composition of this embodiment preferably contains a water-soluble organic compound that contributes to the formation of a polished surface having high surface flatness.

  In the polishing liquid composition of the present embodiment, an unprecedented composite oxide particle containing cerium and zirconium is used as an abrasive, and the polishing rate can be improved, and a water-soluble organic compound is included as an additive. This makes it possible to form a polished surface with high flatness.

  The reason is estimated as follows. As described above, the composite oxide particles containing cerium and zirconium contained in the polishing composition of the present embodiment can act as abrasive grains that enable both reduction of scratches and high-speed polishing. When the polishing composition of the present embodiment is applied to the surface to be polished, the water-soluble organic compound is adsorbed on the surface of the composite oxide particles and / or the surface to be polished to form a film. This coating inhibits the action of the composite oxide particles on the surface to be polished. Only after a high polishing load is applied to the surface to be polished, the coating film is destroyed, and the surface of the object to be polished can be polished with the composite oxide particles.

  When polishing an uneven surface as an example of a surface to be polished, if the progress of polishing is estimated from a microscopic viewpoint, a polishing load higher than the set load set in the polishing apparatus is applied to the convex portion in the initial stage. The coating is destroyed and polishing proceeds. On the other hand, since a low load is applied to the concave portion, the concave portion is protected by the coating and is difficult to be polished. That is, the convex portion is selectively polished, the uneven step is reduced, and the flattening proceeds.

  As described above, when the polishing composition of the present embodiment is used, a polishing surface having excellent flatness can be formed in a short time in combination with the effect of the composite oxide particles capable of reducing both scratches and high-speed polishing. Can be obtained at However, these assumptions do not limit the present invention.

  If the set load set in the polishing apparatus is set to such a value that the polishing hardly progresses on a flat surface, the polishing hardly progresses after the uneven step is eliminated. In this case, polishing more than necessary can be easily prevented, which is preferable.

Examples of the water-soluble organic compound include —SO ₃ H group, —SO ₃ Na group (Na is an atom or atomic group that can be substituted with H atom to form a salt), —COOH group, —COONb group (Nb is H atom) And a water-soluble organic compound having at least one of atoms or atomic groups that can form a salt by substitution. When the water-soluble organic compound is a salt, the water-soluble organic compound is preferably a nonmetallic salt that does not contain an alkali metal. The water-soluble organic compound contained in the polishing liquid composition may be not only one type but also two or more types.

  Examples of the water-soluble organic compound include a water-soluble acrylic polymer, an organic acid, a salt thereof, an acidic amino acid, a salt thereof, a neutral or basic amino acid, and a zwitterionic water-soluble low molecular organic compound (hereinafter referred to as “water-soluble organic compound” And at least one selected from the group consisting of simply low molecular organic compounds). The molecular weight of the low molecular weight organic compound is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less, from the viewpoint of ensuring the stability of the polishing composition.

  From the viewpoint of suppressing the dishing phenomenon due to excessive polishing and obtaining a polished surface with excellent flatness, preferred water-soluble acrylic acid polymers include polyacrylic acid, polymethacrylic acid, ammonium polyacrylate, and polyammonium methacrylate. , Ammonium salt of polyacrylic acid, ammonium salt of copolymer of acrylic acid and maleic acid, ammonium salt of copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid and methyl (meth) Examples thereof include ammonium salts of copolymers with acrylates, and among them, ammonium salts of polyacrylic acid are more preferable. The dishing phenomenon is a phenomenon in which a portion corresponding to the concave portion of the polished surface obtained by polishing is dished in a dish shape due to excessive polishing of the concave portion in the polishing of the uneven surface. . This dishing phenomenon occurs remarkably when the distance between adjacent convex portions is larger, that is, when the ratio of the total area of the concave portions visible when the concave and convex surfaces are viewed in plan is large (when the concave surface density is large).

  The water-soluble acrylic acid polymer has a weight average molecular weight of 300 to 100,000 from the viewpoint of suppressing a dishing phenomenon due to excessive polishing and obtaining a polished surface with excellent flatness and dispersion stability of abrasive grains. And preferably 500 to 50000, more preferably 1000 to 30000, and even more preferably 2000 to 10000. For the same reason, the weight average molecular weight of the salt of the water-soluble acrylic acid polymer is preferably within the above range. When the water-soluble acrylic polymer is ammonium polyacrylate, the weight average molecular weight is preferably 1000 to 20000, and more preferably 2000 to 10,000.

  In the polishing composition of the present embodiment, the weight ratio of ammonium polyacrylate to composite oxide particles (polyammonium acrylate / composite oxide particles) is 1/2 from the viewpoint of effectively suppressing the occurrence of dishing. 5 or more are preferable, More preferably, it is 1/4 or more, More preferably, it is 1/3 or more. The weight ratio (polyammonium acrylate / composite oxide particles) is preferably 15/1 or less, more preferably 12/1 or less, and even more preferably 10/1 or less, from the viewpoint of further improving the polishing rate. . Accordingly, the weight ratio is preferably 1/5 to 15/1, more preferably 1/4 to 12/1, and still more preferably 1/3 to 10/1.

  Preferred examples of the organic acid and salts thereof included in the polishing composition of the present embodiment as an example of a water-soluble organic compound include malic acid, lactic acid, tartaric acid, gluconic acid, citric acid-hydrate, oxalic acid, Examples thereof include adipic acid, fumaric acid, and ammonium salts thereof.

  Preferable specific examples of acidic amino acids and salts thereof contained in the polishing composition of the present embodiment as an example of the water-soluble organic compound include aspartic acid, glutamic acid, and ammonium salts thereof.

  Preferable specific examples of neutral or basic amino acids contained in the polishing composition of this embodiment as an example of the water-soluble organic compound include glycine, 4-aminobutyric acid, 6-aminohexanoic acid, and 12-aminolauric acid. Arginine, glycylglycine and the like.

Preferred examples of the low molecular weight organic compound contained in the polishing composition of the present embodiment as an example of the water-soluble organic compound include dihydroxyethylglycine (DHEG), ethylenediaminetetraacetic acid (EDTA), and cyclohexanediaminetetraacetic acid (CyDTA). Nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), L-glutamic acid diacetic acid (GLDA), aminotri (methylenephosphonic acid), 1- Hydroxyethylidene 1,1-diphosphonic acid (HEDP), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), β-alanine diacetate (β-ADA), α-alanine diacetate (α ADA), aspartic acid diacetic acid (ASDA), ethylenediaminenicosuccinic acid (EDDS), iminodiacetic acid (IDA), hydroxyethyliminodiacetic acid (HEIDA), 1,3-propanediaminetetraacetic acid (1,3-PDTA), Aspartic acid, serine, cysteine, azaserine, asparagine, 2-aminobutyric acid, 4-aminobutyric acid, alanine, β-alanine, arginine, alloisoleucine, alloleucine, isoleucine, ethionine, ergothioneine, ornithine, canavanine, S- (carboxymethyl) ) -Cysteine, kynurenine, glycine, glutamine, glutamic acid, creatine, sarcosine, cystathionine, cystine, cysteic acid, citrulline, β- (3,4-dihydroxyphenyl) -alanine, 3,5-diiodothylo , Taurine, thyroxine, tyrosine, tryptophan, threonine, norvaline, norleucine, valine, histidine, 4-hydroxyproline, δ-hydroxylysine, phenylalanine, proline, homoserine, methionine, 1-methylhistidine, 3-methylhistidine, lanthionine, Lysine, leucine, m-aminobenzoic acid, p-aminobenzoic acid, β-aminoisovaleric acid, 3-aminocrotonic acid, o-aminocinnamic acid, m-aminoaminobenzenesulfonic acid, p-aminobenzenesulfonic acid, 2 -Aminopentanoic acid, 4-aminopentanoic acid, 5-aminopentanoic acid, 2-amino-2-methylbutyric acid, 3-aminobutyric acid, isatinic acid, 2-quinolinecarboxylic acid, 3-quinolinecarboxylic acid, 4-quinolinecarboxylic acid Acid, 5-quinolinecarbo Acid, 2,3-quinoline dicarboxylic acid, 2,4-quinoline dicarboxylic acid, guanidinoacetic acid, 2,3-diaminobenzoic acid, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,4-diamino Benzoic acid, 3,5-diaminobenzoic acid, 2,4-diaminophenol, 3,4-diaminophenol, 2,4,6-triaminophenol, 2-pyridinecarboxylic acid, nicotinic acid, isonicotinic acid, 2, 3-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 2,5-pyridinedicarboxylic acid, 2,6-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 2,4, 5-pyridinetricarboxylic acid, 2,4,5-pyridinetricarboxylic acid, 3,4,5-pyridinetricarboxylic acid, N-phenylglycine, N- Phenylglycine-o-carboxylic acid, phenol-2,4-disulfonic acid, o-phenolsulfonic acid, m-phenolsulfonic acid, p-phenolsulfonic acid, phthalanilic acid, o- (methylamino) phenol, m- (methyl Amino) phenol, p- (methylamino) phenol, carboxybetaine, sulfobetaine, imidazolinium betaine, lecithin and the like. Also, one or more protons of these compounds, F, Cl, Br, and atoms of I, etc. or OH, CN, and substituted derivatives thereof in NO atomic groups, such as _2,. Among these, the following chelating agents are more preferable from the viewpoint of suppressing a dishing phenomenon due to excessive polishing and obtaining a polished surface with excellent flatness.

  Examples of the chelating agent include DHEG, EDTA, CyDTA, NTA, HEDTA, DTPA, TTHA, GLDA, aminotri (methylenephosphonic acid), HEDP, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), and β-ADA. , Α-ADA, ASDA, EDDS, IDA, HEIDA, 1,3-PDTA, aspartic acid, serine, cysteine and the like. Among these, DHEG, EDTA, NTA, β-ADA, α-ADA, ASDA, EDDS, HEIDA, aspartic acid, serine, and cysteine are more preferable.

  Among chelating agents, DHEG is more preferable from the viewpoint of ensuring the stability of the polishing composition at the time of concentration.

  Among amphoteric, water-soluble, low-molecular-weight organic compounds, especially DHEG has an anion group, a cation group, and a nonion group in a balanced state in the molecule. It is presumed that the hydrophilicity is not greatly reduced and the effect of the dispersant is hardly affected. Further, DHEG can sufficiently suppress aggregation of the composite oxide particles and the like, and can ensure the dispersion stability of the composite oxide particles even when the concentration of the composite oxide particles is high. Therefore, the polishing composition of this embodiment containing DHEG can also be provided as a high concentration polishing composition with stable quality.

  The low molecular weight organic compound is usually used in the production of the polishing liquid composition in the form of a free acid or a salt, but a salt having high solubility in an aqueous medium is preferably used in the production of the polishing liquid composition.

  Specific examples of the salt include ammonium compound salts, lithium salts, sodium salts, potassium salts, cesium salts, and the like. From the viewpoint of obtaining preferable electrical characteristics of LSI, ammonium compound salts are more preferable.

  Preferable examples of amines constituting the ammonium compound salt include ammonia, a primary amine having a linear or branched saturated or unsaturated alkyl group having 1 to 10 carbon atoms, a secondary amine, a tertiary amine, Alternatively, a primary amine having at least one aromatic ring having 6 to 10 carbon atoms, a secondary amine, a tertiary amine, an amine having a cyclic structure such as piperidine or piperazine, or a tetraalkylammonium compound such as tetramethylammonium. Is mentioned.

  From the viewpoint of obtaining a polished surface with excellent flatness, the content of the water-soluble organic compound contained in the polishing composition of the present embodiment is preferably 0.02 to 15% by weight, more preferably 0.05 to 10%. % By weight, more preferably 0.1 to 8% by weight, and still more preferably 0.2 to 6% by weight.

  In the polishing composition of the present invention, the substance added as the water-soluble organic compound and the substance added as the above-mentioned dispersant may be the same as well as the case where they are different from each other. When the substance added as the water-soluble organic compound is the same as the substance added as the above-mentioned dispersant, the water-soluble organic compound is used so that suitable dispersibility and suitable flatness of the polishing surface can be realized. Water-soluble organic compound within the range of the total amount of the preferable content of the organic organic compound (for example, 0.02 to 15% by weight) and the preferable content of the dispersant (for example, 0.0005 to 0.5% by weight) What is necessary is just to select the total amount of a dispersing agent.

  The weight ratio of the water-soluble organic compound to the composite oxide particles (water-soluble organic compound / composite oxide particles) in the polishing composition of the present embodiment is from the viewpoint of forming a polished surface having high surface flatness. 1/30 or more is preferable, more preferably 1/20 or more, and still more preferably 1/10 or more. The weight ratio is preferably 15/1 or less, more preferably 12/1 or less, and even more preferably 10/1 or less, from the viewpoint of further improving the polishing rate. Accordingly, the weight ratio is preferably 1/30 to 15/1, more preferably 1/20 to 12/1, and still more preferably 1/10 to 10/1.

  Further, in the case of a polishing liquid composition containing DHEG as a water-soluble organic compound, the content of DHEG contained in the polishing liquid composition is 0.1 to 15% by weight from the viewpoint of obtaining a polished surface with better flatness. Is preferable, more preferably 0.2 to 10% by weight, still more preferably 0.5 to 8% by weight, and still more preferably 1.0 to 6% by weight.

  In the polishing composition of the present embodiment, the weight ratio of DHEG and composite oxide particles (DHEG / composite oxide particles) is preferably 1/5 or more from the viewpoint of effectively suppressing the occurrence of dishing. Preferably it is 1/4 or more, more preferably 1/3 or more. The weight ratio (DHEG / composite oxide particles) is preferably 15/1 or less, more preferably 12/1 or less, and even more preferably 10/1 or less, from the viewpoint of further improving the polishing rate. Accordingly, the weight ratio is preferably 1/5 to 15/1, more preferably 1/4 to 12/1, and still more preferably 1/3 to 10/1.

  The polishing composition of this embodiment may further contain at least one optional component selected from a pH adjuster, a preservative, and an oxidizing agent as long as the effects of the present invention are not hindered. .

  Examples of the pH adjuster include basic compounds and acidic compounds. Examples of basic compounds include ammonia, potassium hydroxide, water-soluble organic amines and quaternary ammonium hydroxides. Examples of the acidic compound include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and organic acids such as acetic acid, oxalic acid, succinic acid, glycolic acid, malic acid, citric acid and benzoic acid.

  Examples of preservatives include benzalkonium chloride, benzethonium chloride, 1,2-benzisothiazolin-3-one, (5-chloro-) 2-methyl-4-isothiazolin-3-one, hydrogen peroxide, or hypochlorite Examples include acid salts.

  Examples of the oxidizing agent include peroxides such as permanganic acid and peroxo acid, chromic acid, nitric acid, and salts thereof.

  The pH at 25 ° C. of the polishing composition of the present embodiment is not particularly limited, but is preferably 2 to 10, more preferably 3 to 9, more preferably 4 to 8, since the polishing rate can be further improved. More preferably, it is 4.5-7. Here, the pH at 25 ° C. can be measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and is a value one minute after immersion of the electrode in the polishing composition.

  Next, an example of a method for preparing the polishing composition of this embodiment will be described.

  An example of the manufacturing method of the polishing liquid composition of this embodiment is not restrict | limited at all, For example, it can prepare by mixing composite oxide particle | grains, a dispersing agent, an aqueous medium, and an arbitrary component as needed. .

  The dispersion of the composite oxide particles in the aqueous medium can be performed using, for example, a stirrer such as a homomixer, a homogenizer, an ultrasonic disperser, a wet ball mill, or a bead mill. After the composite oxide particles are dispersed in the aqueous medium, when the coarse particles formed by aggregation of the composite oxide particles are contained in the aqueous medium, it is preferable to remove the coarse particles by centrifugation, filter filtration, or the like. . The composite oxide particles are preferably dispersed in an aqueous medium in the presence of a dispersant.

  The polishing composition of the present embodiment is applied to polishing in the production process of a precision component substrate or polishing of a glass surface of a liquid crystal display panel. As a substrate for precision parts, a glass substrate constituting a hard disk or the like, a substrate constituting a semiconductor device having an oxide film (for example, a silicon oxide film) as an outermost layer (substrate for a semiconductor device), or a crystallized glass such as a glass ceramic substrate. Examples thereof include chemically tempered glass substrates such as substrates, aluminosilicate glass substrates, and synthetic quartz glass substrates used for photomask substrates. The polishing composition of this embodiment is suitable for use in a polishing step in the process of manufacturing a glass substrate or a semiconductor device substrate that constitutes a hard disk or the like.

  Next, a polishing method using the polishing composition of this embodiment will be described.

  In an example of the polishing method performed using the polishing liquid composition of the present embodiment, the polishing liquid composition is supplied between the polishing target substrate and the polishing pad constituting the polishing apparatus, and the polishing target substrate and the polishing pad The substrate to be polished is polished by moving the polishing pad relative to the substrate to be polished while being in contact with the substrate.

  The polishing pad is attached to a polishing surface plate such as a rotary table, for example. The substrate to be polished is held by a carrier or the like. The polishing apparatus may be a double-side polishing apparatus capable of simultaneously polishing both main surfaces of a plate-shaped polishing target substrate, or may be a single-side polishing apparatus capable of polishing only one side.

(Manufacture of glass substrates)
There is no restriction | limiting in particular about the material of the polishing pad used at the grinding | polishing process of the manufacture process of a glass substrate, A conventionally well-known thing can be used.

  Examples of the material to be polished include quartz glass, soda lime glass, aluminosilicate glass, boron silicate glass, aluminoboron silicate glass, alkali-free glass, crystallized glass, and glassy carbon. Among these, the polishing liquid composition of the present embodiment is a polishing process performed in the manufacturing process of an aluminosilicate glass substrate, a glass ceramic substrate (crystallized glass substrate), a synthetic quartz glass substrate, and the like, which are examples of a tempered glass substrate. Can be suitably used. The aluminosilicate glass substrate has good chemical durability and is less susceptible to damage (such as recess defects) due to alkali cleaning performed for the purpose of removing particles remaining on the polished substrate. It is preferable in that a quality glass substrate can be provided. A synthetic quartz glass substrate is preferable in that it has excellent optical characteristics such as transmittance.

  There is no restriction | limiting in particular about the shape of a glass substrate, For example, the shape which has flat parts, such as a disk shape, plate shape, slab shape, prism shape, the shape which has curved surface parts, such as a lens, etc. are mentioned. In particular, the polishing liquid composition of the present embodiment can be suitably used in a polishing process performed in the process of manufacturing a disk-shaped or plate-shaped glass substrate.

  In the manufacturing process of the glass substrate, the polishing load applied to the substrate to be polished by the polishing apparatus is preferably 3 kPa or more, more preferably 4 kPa or more, further preferably 5 kPa or more, and more preferably 5.5 kPa or more from the viewpoint of improving the polishing rate. Even more preferable. Further, from the viewpoint of improving the quality of the polished surface and relaxing the residual stress on the polished surface, the polishing load is preferably 12 kPa or less, more preferably 11 kPa or less, further preferably 10 kPa or less, and even more preferably 9 kPa or less. Accordingly, the polishing load is preferably 3 to 12 kPa, more preferably 4 to 11 kPa, still more preferably 5 to 10 kPa, and even more preferably 5.5 to 9 kPa.

The supply rate of the polishing liquid composition varies depending on the sum of the area of the surface of the polishing pad facing the substrate to be polished and the area of the polishing target surface of the substrate to be polished and the composition of the polishing liquid composition. From the viewpoint of improvement, it is preferably 0.06 to 5 ml / min per 1 cm ^{2 of the} surface to be polished, more preferably 0.08 to 4 ml / min, and more preferably 0.1 to 3 ml / min.

  As for the rotation speed of a polishing pad, 10-200 rpm is preferable, More preferably, it is 20-150 rpm, More preferably, it is 30-60 rpm.

(Thin film polishing performed in the manufacturing process of semiconductor devices)
The polishing liquid composition of this embodiment can also be used, for example, for polishing a thin film in which one main surface of a semiconductor substrate is arranged on the side.

  Examples of the material of the semiconductor substrate include elemental semiconductors such as Si or Ge, compound semiconductors such as GaAs, InP, or CdS, mixed crystal semiconductors such as InGaAs, HgCdTe, and the like.

Thin film materials include metals such as aluminum, nickel, tungsten, copper, tantalum, and titanium; semi-metals such as silicon; alloys based on the above metals; glassy, glassy carbon, or glassy such as amorphous carbon Substances: Ceramic materials such as alumina, silicon dioxide, silicon nitride, tantalum nitride, or titanium nitride; materials constituting semiconductor devices such as resins such as polyimide resins. Among these, the thin film preferably contains silicon from the viewpoint that it can be polished at a high speed, and more preferably contains at least one selected from the group consisting of silicon oxide, silicon nitride, and polysilicon. preferable. Examples of silicon oxide include silicon dioxide and tetraethoxysilane (TEOS). The thin film containing silicon oxide may be doped with elements such as phosphorus and boron. Specific examples of such a thin film include BPSG (Boro-Phospho-Silicate Glass) film and PSG (Phospho-Silicate Glass). ) A film etc. are mentioned.

  The thin film forming method may be appropriately selected according to the material constituting the thin film, and examples thereof include a CVD method, a PVD method, a coating method, and a plating method.

  In polishing the thin film, the polishing load applied to the thin film by the polishing apparatus is preferably 5 kPa or more, more preferably 10 kPa or more from the viewpoint of improving the polishing rate. Further, from the viewpoint of improving the quality of the polished surface and relaxing the residual stress on the polished surface, the polishing load is preferably 100 kPa or less, more preferably 70 kPa or less, and even more preferably 50 kPa or less. Therefore, the polishing load is preferably 5 to 100 kPa, more preferably 10 to 70 kPa, and still more preferably 10 to 50 kPa.

The supply rate of the polishing liquid composition varies depending on the total area of the surface of the polishing pad facing the polishing target substrate and the area of the thin film polishing target surface and the composition of the polishing liquid composition, but improves the polishing rate. From the viewpoint, 0.01 ml / min or more per 1 cm ^{2 of the} surface to be polished is preferable, and more preferably 0.1 ml / min or more. Further, from the viewpoint of cost reduction and ease of waste liquid treatment, the supply rate of the polishing liquid composition is preferably 10 ml / min or less, more preferably 5 ml / min or less per 1 cm ^{2 of the} surface to be polished. Therefore, the supply rate of the polishing composition is preferably 0.01 to 10 ml / min, more preferably 0.1 to 5 ml / min per 1 cm ^{2 of the} surface to be polished.

  The material of the polishing pad used in the polishing process is not particularly limited, and conventionally known materials can be used. Examples of the material of the polishing pad include organic polymer foams such as hard foamed polyurethane, inorganic foams, etc., among which hard foamed polyurethane is preferable.

  The rotational speed of the polishing pad is preferably 30 to 200 rpm, more preferably 45 to 150 rpm, and still more preferably 60 to 100 pm.

  The thin film may be a thin film having an uneven surface. A thin film having a concavo-convex surface is formed by, for example, a thin film forming process in which one main surface on a semiconductor substrate forms a crocodile thin film, and a concavo-convex surface formation in which the semiconductor substrate of this thin film forms a concavo-convex pattern on the opposite surface It can obtain through a process. The concave / convex pattern can be formed using a conventionally known lithography method or the like. Moreover, the surface opposite to the surface on the side of the semiconductor substrate of the thin film may be formed unevenly corresponding to the unevenness of the lower layer. In polishing a thin film having an uneven surface, it is preferable that the polishing load, the supply rate of the polishing composition, the material of the polishing pad, the number of rotations of the polishing pad, and the like are the same as those for polishing the thin film.

The polishing composition of this embodiment can be used for any polishing in the manufacturing process of a semiconductor device. As specific examples, for example, (1) polishing performed in a step of forming an embedded isolation film, (2) polishing performed in a step of planarizing an interlayer insulating film, and (3) embedded metal wiring (for example, damascene wiring) Etc.) and (4) polishing performed in the step of forming the embedded capacitor.

  Examples of the semiconductor device include a memory IC (Integrated Circuit), a logic IC, and a system LSI (Large-Scale Integration).

<Substrate for polishing>
Silicon wafer with thermal oxide film A silicon dioxide film having a thickness of 2000 nm formed on a silicon wafer having a diameter of 20.32 cm (8 inches) was prepared. The silicon dioxide film can be formed by placing a silicon wafer in an oxidation furnace and exposing it to oxygen gas or steam to cause the silicon in the silicon wafer to react with oxygen.

<Polishing conditions>
Polishing tester: Single-side polishing machine (Part No .: LP-541, manufactured by Lapmaster SFT, surface plate diameter 540 mm)
Polishing pad: Laminated pad of IC1000 (hard urethane pad) and suba400 (nonwoven fabric type pad) (made by Nitta Haas Co., Ltd.)
Surface plate rotation speed: 100 rpm
Head rotation speed: 110 rpm (the rotation direction is the same as the surface plate)
Polishing time: 1 min
Polishing load: 30 kPa (set value)
Polishing liquid composition supply amount: 200 ml / min

<Evaluation method>
After polishing the substrate to be polished using the polishing composition of Examples 1 to 4 and Comparative Examples 1 and 2 (see Tables 1 to 3), the substrate was washed with running water using ion-exchanged water, and then ion-exchanged water. The sample was ultrasonically cleaned (100 kHz, 3 min) while being immersed in water, further washed with ion-exchanged water, and finally dried by a spin dry method.

(Preparation of slurries A to D)
Predetermined volumes described in Table 2 obtained by wet-grinding the predetermined fired products described in Table 1 by a bead mill in water to which a dispersant (ammonium polyacrylate, weight average molecular weight 6000) was added. A slurry containing Ce _0.75 Zr _0.25 O ₂ particles having a median diameter (Ce _0.75 Zr _0.25 O ₂ particles: 25% by weight) was prepared. All the fired products (1) to (4) shown in Table 1 were obtained by firing unfired Ce _0.75 Zr _0.25 O ₂ particles (trade name Actals 9320, manufactured by Rhodia), and the firing temperature was It is as described in Table 1. Note that all of the unfired Ce _0.75 Zr _0.25 O ₂₂ particles (trade name Actals 9320, manufactured by Rhodia) were obtained using a cerium (IV) compound and a zirconium (IV) compound as raw materials.

(Preparation of slurry E)
In water to which a dispersing agent (ammonium polyacrylate, weight average molecular weight 6000) was added, a fired product (5) (Ce _0.74 Zr _0.26 O ₂ particles by a bead mill so that the volume median diameter would be the value shown in Table ) Was obtained by wet pulverization of Ce _0.74 Zr _0.26 O ₂ particles slurry (Ce _0.74 Zr _0.26 O ₂ particles: 25% by weight). The fired product (5) is obtained using a cerium (III) compound and a zirconium (IV) compound as raw materials.

Details of Ce _0.74 Zr _0.26 O ₂ process for preparing a particle slurry is as follows.

  First, in a 30 L reaction vessel, 4280 g of a 37.7 wt% cerium (III) nitrate salt solution and 1070 g of a 54.8 wt% zirconium nitrate (IV) salt solution were stirred and mixed. The pH of the obtained liquid mixture was 1.26. Next, 10 L of deionized water was added to the mixture.

  Next, 3.8 mol / L of ammonia water was continuously added to the above mixed solution to which deionized water was added at a supply rate of 1.7 L / hr. When the pH of the liquid mixture thus obtained is 7.2, 1148 ml of 5.8 mol / L hydrogen peroxide water is added, and ammonia water is continuously added so that the pH is stabilized, A coprecipitate of cerium hydroxide and zirconium hydroxide was obtained. The total amount of ammonia water added is 2420 ml, and the amount of hydrogen peroxide water (5.8 M) added is 1148 ml.

  Next, the coprecipitate was filtered with a filter paper and washed with deionized water. The obtained washed product was fired at 1130 ° C. for 2 hours, and then coarse particles were removed from the fired product using a 60 mesh filter. Next, the fired product (5) from which coarse particles were removed by sieving was wet pulverized and then filtered using a pleated filter having a filtration accuracy of 2 μm to obtain slurry E.

(Preparation of slurry F)
Dispersant (ammonium polyacrylate, a weight average molecular weight 6000) in water was added, the fired product by a bead mill (6) (Ce O ₂ grains terminal, by Kou Ski Co., purity: 99.9%) were wet-milled obtained by Rukoto, Ce O ₂ grain terminal slurry volume median diameter of 130 nm (Ce O ₂ grain child: 40 wt%) was prepared as a slurry F. The fired product (6) was obtained by using a cerium (IV) compound as a raw material, and its half-width (half-width of the peak having the largest peak area) was 0.188 °, and the crystallite size was More than 100 nm, BET specific surface area was 7.0 m ² / g.

(Adjustment of polishing composition)
Each slurry adjusted as described above, water, and nitric acid as a pH adjuster are mixed so that the concentrations of the abrasive grains and the dispersant are the concentrations shown in Table 3 to obtain a polishing composition. It was.

(Measurement of BET specific surface area)
The BET specific surface areas of the composite oxide particles and the CeO ₂ particles were measured using a flow type specific surface area automatic measuring apparatus Flowsorb 2300 (manufactured by Shimadzu Corporation). The powder itself was measured for the fired product, and 10 g of the slurry was dried under reduced pressure at 110 ° C. to remove the water, and the powder obtained by crushing with an agate mortar was measured.

(Measurement of volume median diameter (D50))
The volume median diameter (D50) of the composite oxide particles and CeO ₂ particles in each slurry was measured under the following measurement conditions.
Measuring device: Laser diffraction / scattering particle size distribution measuring apparatus LA920 manufactured by Horiba, Ltd.
Circulation strength: 4
Ultrasonic intensity: 4

<Measurement of powder X-ray diffraction>
20 g of each slurry was dried in an atmosphere of 110 ° C. for 12 hours, and then the obtained dried product was crushed with a mortar to obtain a powder X-ray diffraction sample. The results of analyzing each sample by the powder X-ray diffraction method are shown in Table 2. The measurement conditions by the powder X-ray diffraction method were as follows.
(Measurement condition)
Apparatus: Rigaku Co., Ltd., powder X-ray analyzer RINT2500VC
X-ray generation voltage: 40 kV
Radiation: Cu-Kα1 line (λ = 0.154050 nm)
Current: 120 mA
Scan Speed: 10 degrees / min
Measurement step: 0.02 degrees / min

  The peak height of each peak, the half-width of the first peak, the area of each peak, and the crystallite size are determined from the obtained powder X-ray diffraction spectrum, and the powder X-ray diffraction pattern comprehensive analysis attached to the powder X-ray diffractometer Calculation was performed using soft JADE (MDI). The calculation process by the software is performed based on an instruction manual (Jade (Ver. 5) software, instruction manual Manual No. MJ13133E02, Rigaku Corporation) of the software.

<Calculation method of polishing rate>
The thickness of the thermal oxide film before and after polishing was measured using a light interference film thickness meter (trade name: VM-1000, manufactured by Dainippon Screen Mfg. Co., Ltd.), and the polishing rate was calculated from these values as follows. .
Polishing rate (nm / min) = (film thickness before polishing) − (film thickness after polishing)

<Scratch number evaluation method>
A silicon dioxide film having a thickness of 1000 nm formed on a silicon wafer having a diameter of 5 cm (2 inches) was prepared. The silicon dioxide film can be formed by placing a silicon wafer in an oxidation furnace and exposing it to oxygen gas or steam to cause the silicon in the silicon wafer to react with oxygen.
(Polishing conditions)
Polishing tester: Musashino Electronics, MA-300 single-side polishing machine, surface plate diameter of 300 mm,
Polishing pad: Laminated pad of IC1000 (hard urethane pad) and suba400 (nonwoven fabric type pad) (manufactured by Nitta Haas Co., Ltd.)
Surface plate rotation speed: 90 r / min,
Carrier rotation speed: 90 r / min, forced drive type,
Polishing liquid composition supply rate: 50 g / min (about 1.5 mL / min / cm ² ),
Polishing time: 1 min
Polishing load: 300 g / cm ² (constant load by weight)
Dressing conditions: Ion exchange water was supplied for 1 minute before polishing and dressed with a diamond ring.

  Scratches are scratches having a width of 20 nm or more, a length of 50 μm or more, and a depth of about 3 nm or more, which can be observed with MicroMax VMX-2100.

[Measurement method of the number of scratches]
Measuring device: VISION PSYTEC, MicroMax VMX-2100
(Micromax measurement conditions)
Light source: 2Sλ (250 W) and 3Pλ (250 W), both with 100% light
Chilled angle: -9 °
Magnification: Maximum (Field range: 1/35 of the total area of the polished surface)
Observation area: Total area of polished surface (silicon wafer with 2 inch thermal oxide film)
Iris: notch
The scratch evaluation was expressed as a relative value based on the total number of scratches in Comparative Example 2.

  As shown in Table 3, when Examples 1-4 and Comparative Examples 1-2 are compared, when polishing using the polishing composition of Examples 1-4, the polishing liquid of Comparative Examples 1-2 Although the polishing rate is the same or slightly lower than when polishing using the composition, scratches are reduced, indicating that both high-speed polishing and scratch reduction are compatible.

  If polishing is performed using the polishing liquid composition of the present embodiment, the substrate to be polished can be polished at a higher speed and scratches can be reduced. Therefore, the polishing liquid composition of the present embodiment is an oxide film (for example, silicon oxide) Of a synthetic quartz glass substrate used as a substrate constituting a semiconductor device having a film), a chemically strengthened glass substrate such as an aluminosilicate glass substrate, a crystallized glass substrate such as a glass ceramic substrate, a photomask substrate or a lens material for a stepper It is suitably used for polishing in a polishing process performed in the manufacturing process, or polishing of a glass surface of a liquid crystal display panel.

Claims (7)

A polishing liquid composition comprising composite oxide particles containing cerium and zirconium, a dispersant, and an aqueous medium,
The crystallite size of the composite oxide particles is 10 to 50 nm,
In the powder X-ray diffraction spectrum of the composite oxide particles obtained by irradiating with CuKα1 rays (λ = 0.154050 nm),
A peak (first peak) having a peak within a diffraction angle 2θ (θ is a black angle) region 28.68 to 29.11 °,
A peak (second peak) having an apex within a diffraction angle 2θ region of 33.23 to 33.79 °,
A peak having a peak within the diffraction angle 2θ region of 47.71 to 48.53 ° (third peak) and a peak having a peak within the diffraction angle 2θ region of 56.61 to 57.60 ° (fourth peak). Each exists,
The half width of the first peak is 0. 405 ° to 0.525 °,
During the powder X-ray diffraction spectrum, derived from cerium oxide, derived from the peak a ₁ and zirconium oxide that exist in the vertex diffraction angle 2θ region 28.40 to 28.59 °, the apex angle of diffraction 2θ region from 29.69 to 31.60 peak a ₂ present in ° is not present, the polishing composition.   The composite oxide particles are included in the powder X-ray diffraction spectrum.
A peak (first peak) having a peak within a diffraction angle 2θ (θ is a black angle) region 28.862 to 28.913 °,
A peak (second peak) having an apex within a diffraction angle 2θ region of 33.449 to 33.492 °,
There is a peak with a peak in the diffraction angle 2θ region 48.063 to 48.104 ° (third peak) and a peak with the peak in the diffraction angle 2θ region 57.050 to 57.184 ° (fourth peak). The polishing liquid composition according to claim 1, which is used. The area of the second peak is 10 to 50% of the area of the first peak,
The area of the third peak is 35 to 75% of the area of the first peak;
The polishing composition according to claim 1 or 2 , wherein the area of the fourth peak is 20 to 65% of the area of the first peak.   The polishing composition according to any one of claims 1 to 3, wherein a volume median diameter of the composite oxide particles is 30 to 1000 nm. The polishing composition according to any one of claims 1 to 4, wherein the composite oxide particles have a specific surface area of 15 to 100 m ² / g.   The polishing liquid composition according to claim 1 is supplied between a polishing target substrate and a polishing pad, and the polishing pad is in contact with the polishing target substrate and the polishing pad. A polishing method including a step of polishing the substrate to be polished by moving the substrate relative to the substrate to be polished.   The manufacturing method of the board | substrate for precision components including the grinding | polishing process of grind | polishing the at least one main surface of both the main surfaces of a grinding | polishing target board | substrate using the polishing liquid composition in any one of Claims 1-5.