JP2018107329A - Polishing liquid composition for silicon oxide film - Google Patents

Abstract

Kind Code: A1 A polishing liquid composition for a silicon oxide film capable of improving the polishing rate of convex portions while suppressing polishing of concave portions is provided. A polishing liquid composition for a silicon oxide film of the present invention contains particles A whose surfaces are at least partly made of ceria, a water-soluble polymer B, and water. wherein the water-soluble polymer B is a linear polymer and is one or more selected from structural units derived from acrylic acid, structural units derived from acrylate, and structural units derived from vinylpyrrolidone. and has a weight average molecular weight of 2,500,000 or more. Preferably, the 0.1% by mass aqueous solution of water-soluble polymer B at an aqueous solution temperature of 25° C. and pH 6.0 expresses both positive normal stress and negative normal stress in this order due to an increase in shear rate. . [Selection drawing] Fig. 1

Description

  The present invention relates to a polishing liquid composition for a silicon oxide film containing cerium oxide particles, a semiconductor substrate manufacturing method and a polishing method using the same, and a recess protecting liquid and a polishing liquid kit.

  Chemical mechanical polishing (CMP) technology is a method in which a polishing substrate and a polishing pad are relatively moved while supplying a polishing liquid to these contact portions in a state where the surface of the substrate to be polished and the polishing pad are in contact with each other. This is a technique in which the surface unevenness portion of the substrate to be polished is chemically reacted and mechanically removed and flattened by being moved.

  At present, when performing planarization of an interlayer insulating film, formation of a shallow trench isolation structure (hereinafter also referred to as “element isolation structure”), formation of a plug and a buried metal wiring, etc. in a semiconductor element manufacturing process, CMP technology is an essential technology. In recent years, the number of semiconductor elements has increased dramatically and the definition has become higher, and it has been desired that polishing can be performed at high speed while the flatness is better.

  Patent Document 1 discloses a silicon dioxide insulating film containing two types of polyacrylic acids having different weight average molecular weights and having a relatively large weight average molecular weight for the purpose of having excellent flat performance. An aqueous slurry composition for polishing is disclosed. The polyacrylic acid contained in the aqueous slurry composition disclosed in Patent Document 1 is a cross-linked polyacrylic acid. In Patent Document 2, for the purpose of highly flattening, as a polymer electrolyte exhibiting a normal stress effect, for example, for polishing an Al—Cu alloy containing polyacrylic acid having a weight average molecular weight of 2000, A slurry is disclosed. Patent Document 3 discloses an abrasive containing a polyacrylic acid ammonium salt having a molecular weight of 15,000 as an abrasive applicable to shallow trench isolation. Patent Document 4 discloses an aqueous dispersion for CMP containing colloidal silica as abrasive grains and polyvinyl pyrrolidone having a weight average molecular weight exceeding 200,000 for the purpose of polishing a metal film with low friction. . In Patent Document 5, the object of coating polishing is a metal film, and for the purpose of suppressing the occurrence of surface defects, it contains colloidal silica as abrasive grains and has at least two poly (meth) acrylic acids and other carbonyl groups. An aqueous dispersion for CMP containing an organic acid is disclosed.

JP 2006-126889 A JP-A-10-168431 JP 2000-160136 A JP 2007-88424 A JP 2009-27142 A

  As abrasive grains used for polishing a silicon oxide film, cerium oxide (hereinafter, also referred to as “ceria”) particles are generally used. Ceria particles having various shapes and sizes (hereinafter, also referred to as “amorphous ceria”) such as calcined and ground ceria are widely used. However, when this polishing composition containing ceria particles and a water-soluble polymer is used for flattening a silicon oxide film having an uneven step surface and a relatively wide protrusion, the polishing of the recess However, it was a problem that the polishing rate of the convex portion was significantly reduced.

  The present invention relates to a polishing composition for a silicon oxide film capable of improving the polishing rate of a convex portion while suppressing polishing of the concave portion, a method for manufacturing and polishing a semiconductor substrate using the same, and a concave portion protecting liquid and a polishing liquid Provide kit.

The polishing composition for a silicon oxide film of the present invention is a polishing composition for a silicon oxide film containing particles A having at least part of the surface made of ceria, a water-soluble polymer B, and water. ,
The water-soluble polymer B is a linear polymer and includes one or more structural units selected from a structural unit derived from acrylic acid, a structural unit derived from acrylate, and a structural unit derived from vinylpyrrolidone. The weight average molecular weight is 2.5 million or more.

  A polishing liquid kit for producing a polishing liquid composition for a silicon oxide film of the present invention comprises a first liquid in which an aqueous dispersion of particles A having at least part of the surface made of ceria is contained in a container, A structure in which an aqueous solution of molecule B includes a second liquid stored in a container different from the container in which the first liquid is stored, and the water-soluble polymer B is a linear polymer and is derived from acrylic acid One or more structural units selected from a unit, a structural unit derived from an acrylate, and a structural unit derived from vinyl pyrrolidone are included, and the weight average molecular weight is 2.5 million or more.

  The concave portion protecting liquid of the present invention is a concave portion protecting liquid that is used together with an aqueous dispersion of particles A, the surface of which is at least partly made of ceria. Water and a water-soluble polymer B dissolved in the water The water-soluble polymer B is a linear polymer, and one or more components selected from a structural unit derived from acrylic acid, a structural unit derived from acrylate, and a structural unit derived from vinylpyrrolidone Including the unit, the weight average molecular weight is 2.5 million or more.

  The manufacturing method of the semiconductor device of this invention includes the process of grind | polishing the uneven | corrugated level | step difference surface of a silicon oxide film using the polishing liquid composition for silicon oxide films of this invention.

  The method for polishing an uneven step surface of the present invention includes a step of polishing the uneven step surface of a silicon oxide film using the polishing composition for a silicon oxide film of the present invention, wherein the silicon oxide film is used for manufacturing a semiconductor device. It is an insulating film formed in the process.

  According to the present invention, a polishing liquid composition for a silicon oxide film capable of improving the polishing rate of a convex portion while suppressing polishing of the concave portion, a semiconductor substrate manufacturing method and polishing method using the same, and a concave portion protecting liquid, A polishing liquid kit is provided.

FIG. 1 is a graph showing the relationship between the shear rate applied to the 0.1% by mass water-soluble polymer B1 aqueous solution and the normal stress. FIG. 2 is a graph showing the relationship between the shear rate applied to the 0.1 mass% water-soluble polymer B3 aqueous solution and the normal stress. FIG. 3 is a graph showing the relationship between the shear rate applied to the 0.1% by mass water-soluble polymer B5 aqueous solution and the normal stress. FIG. 4 is a graph showing the relationship between the shear rate applied to the 0.1% by mass water-soluble polymer B10 aqueous solution and the normal stress.

  As a result of intensive studies by the present inventors, in a polishing liquid composition containing, as abrasive grains, particles having at least part of the surface made of ceria, it is a linear polymer, a structural unit derived from acrylic acid, an acrylate When a water-soluble polymer having a weight average molecular weight of 2.5 million or more is included, the polishing of the silicon oxide film includes at least one structural unit selected from structural units derived from When used in the above, it is based on the knowledge that the polishing rate of the convex portion can be improved while suppressing the polishing of the concave portion.

  When polishing the uneven step surface of the silicon oxide film using the polishing liquid composition of the present invention, for the reason that it is possible to improve the polishing rate of the convex portion while suppressing the polishing of the concave portion, Although it is not clear, it is estimated as follows.

  Conventionally, polyacrylic acid having a weight average molecular weight of about tens of thousands has been used as a concave polishing inhibitor for a silicon oxide film having a narrow convex width, but this polyacrylic acid can be obtained by increasing the amount of polymer added. The improvement of the recess polishing suppression effect has been realized. However, in order to improve the concave polishing suppression effect, increasing the amount of polymer added decreases the convex polishing rate, especially when the convex width is relatively wide. It was a problem to be lowered. On the other hand, in the polishing liquid composition of the present invention, as a concave polishing inhibitor, it is a linear polymer, a constitutional unit derived from acrylic acid, a constitutional unit derived from acrylate, and a constitution derived from vinylpyrrolidone. By using a water-soluble polymer containing one or more structural units selected from the units and having a weight average molecular weight of 2.5 million or more, the recess polishing inhibitor is thin and homogeneous with respect to the uneven step surface of the silicon oxide film. It is possible to form a protective layer, and it is presumed that the high polishing rate of the convex portions and the suppression of polishing of the concave portions can both be achieved.

[Particle A whose surface is at least partially made of ceria]
The polishing composition of the present invention contains particles A (hereinafter sometimes abbreviated as “particles A”) in which at least a part of the surface is made of ceria as polishing abrasive grains. The particles A are preferably other than crushing ceria particles Aa (hereinafter sometimes abbreviated as “particles Aa”), colloidal ceria particles Ab (hereinafter sometimes abbreviated as “particles Ab”), and ceria. It is one or more selected from particles Ac in which ceria is coated on the particles (hereinafter sometimes abbreviated as “particle Ac”).

  The particles Aa can be obtained, for example, by firing and pulverizing a cerium compound such as cerium carbonate or cerium nitrate. The particles Ab can be obtained by a build-up process, for example, by the method described in Examples 1 to 4 of JP-T-2010-505735. Examples of the particles Ac include composite particles (ceria-coated silica particles) having a structure in which at least a part of the surface of the silica particles is coated with granular ceria. The composite particles, for example, deposit ceria on the silica particles. Can be obtained. Ceria-coated silica particles can be obtained, for example, by the method described in Examples 1 to 14 of JP-A-2015-63451 or Examples 1 to 4 of JP-A-2013-119131. As the particles A, colloidal ceria is preferable from the viewpoint of improving the polishing rate, and ceria-coated silica particles are preferable from the viewpoint of reducing the residue after polishing.

The average primary particle size of the particles A is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more from the viewpoint of improving the polishing rate, and preferably 300 nm or less, from the viewpoint of suppressing generation of polishing flaws, 200 nm The following is more preferable, and 150 nm or less is still more preferable. In the present disclosure, the average primary particle size of the particles A is calculated using a BET specific surface area S (m ² / g) calculated by a BET (nitrogen adsorption) method. The BET specific surface area can be measured by the method described in Examples.

  Examples of the shape of the particle A include a substantially spherical shape, a polyhedral shape, and a raspberry shape.

  The content of the particles A in the polishing composition of the present invention is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably from the viewpoint of ensuring cost and ensuring the polishing rate. It is 0.5% by mass or more, and preferably 10% by mass or less, more preferably 6% by mass or less, and still more preferably 1% by mass or less.

[Water-soluble polymer B]
The polishing composition according to the present disclosure is a linear polymer as a polishing aid from the viewpoint of suppressing polishing of concave portions and improving the polishing rate of convex portions, and is derived from a structural unit derived from acrylic acid and an acrylate. And a water-soluble polymer B having a weight average molecular weight of 2.5 million or more (hereinafter, abbreviated as “polymer B” in some cases). .)including. The linear polymer has a structure in which structural units (monomers) are linearly connected, and is also expressed as a chain polymer or a one-dimensional polymer.

  The polymer B may take the form of a salt in which an anionic group such as a carboxylic acid group is neutralized. Examples of the counter ion when the anionic group is in the form of a salt include metal ions, ammonium ions, alkylammonium ions, and the like. From the viewpoint of improving the quality of the semiconductor substrate, ammonium ions are preferable. Polymer B in the form of ammonium salt is prepared by, for example, mixing polymer B in the form of a metal salt such as Na salt, a cation exchange resin, and water, stirring the mixture for a predetermined time, and then filtering the cation exchange resin. Metal ions and hydrogen ions are ion-exchanged, and then neutralized with ammonia.

  Examples of the polymer B include at least one selected from polyacrylic acid, polyvinylpyrrolidone, a copolymer of acrylic acid and monomethoxypolyethylene glycol mono (meth) acrylate, an alkali metal salt thereof, and an ammonium salt thereof. From the viewpoint of improving the quality of the semiconductor substrate, polyacrylic acid or polyvinylpyrrolidone is preferable, and polyacrylic acid is preferable.

  The weight average molecular weight of the polymer B is 2.5 million or more, preferably 3 million or more, more preferably 4 million or more, and the same viewpoint, from the viewpoint of suppressing polishing of the concave portion and improving the polishing rate of the convex portion. Preferably it is 10 million or less, More preferably, it is 8 million or less, More preferably, it is 6 million or less.

The weight average molecular weight of the polymer B can be measured by gel permeation chromatography (GPC) using liquid chromatography (manufactured by Hitachi, Ltd., L-6000 type high performance liquid chromatography) under the following conditions.
Detector: Shodex RI SE-61 differential refractive index detector Column: G4000PWXL and G2500PWXL manufactured by Tosoh Corporation were connected in series.
Eluent: 0.2 M phosphate buffer / acetonitrile = 90/10 (volume ratio) was adjusted to a concentration of 0.5 g / 100 mL, and 20 μL was used.
Column temperature: 40 ° C
Flow rate: 1.0 mL / min
Standard polymer: monodisperse polyacrylamide with known molecular weight

  From the viewpoint of suppressing the polishing of the concave portion and improving the polishing rate of the convex portion, the polymer B has a shear rate applied to a 0.1 mass% aqueous solution (25 ° C. aqueous solution) of pH 6.0 of the polymer B as a horizontal axis. In the graph with the normal stress acting on the liquid surface of the aqueous solution as the vertical axis when added to the aqueous solution, a positive normal stress and a negative normal stress are expressed in this order by increasing the shear rate. Is preferred. From the same viewpoint, the normal stress is preferably a positive value at the shear rate X (1 / s) and a negative value at the shear rate Y (1 / s). However, the shear rate Y (1 / s) is larger than the shear rate X (1 / s). The shear rate X (1 / s) is preferably a value within the range of 0 to 3000 (1 / s), more preferably 10 to 2500 (1 / s), and even more preferably 534 (1 / s). is there. The shear rate Y (1 / s) is preferably a value in the range of 3000 to 10000 (1 / s), more preferably 5000 to 10000 (1 / s), and more preferably 8500 (1 / s). is there.

  The content of the polymer B in the polishing composition of the present invention is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, from the viewpoint of suppressing the polishing of the concave portions and improving the polishing rate of the convex portions. Further, it is preferably 0.03% by mass or more, and preferably 0.15% by mass or less, more preferably 0.10% by mass or less, and further preferably 0.06% by mass or less.

  The mass ratio (B / A) between the particles A and the polymer B in the polishing composition of the present invention is preferably 0.005 or more, more preferably from the viewpoint of suppressing polishing of the concave portions and improving the polishing rate of the convex portions. Is 0.01 or more, more preferably 0.05 or more, and preferably 0.5 or less, more preferably 0.2 or less, and still more preferably 0.1 or less.

[water]
The polishing composition of the present invention contains water as a medium. The water is more preferably water such as ion-exchanged water, distilled water or ultrapure water from the viewpoint of improving the quality of the semiconductor substrate. The content of water in the polishing composition of the present invention is such that the total of the masses of particles A, polymer B, water and the following optional components is 100% by mass, excluding particles A, polymer B and optional components. It can be a residue.

[Other ingredients]
The polishing liquid composition of the present invention can contain other components as long as the effects of suppressing the polishing of the concave portions and improving the polishing rate of the convex portions are not impaired. Examples of other components include pH adjusters and polishing aids other than Compound B. Furthermore, examples of other components include a thickener, a dispersant, a rust inhibitor, a basic substance, a polishing rate improver, a surfactant, and a polymer compound other than the polymer B. The content of these optional components is preferably 0.001% by mass or more, more preferably 0.0025% by mass or more, still more preferably 0.01% by mass or more from the viewpoint of ensuring the polishing rate, From the viewpoint of improving the polishing rate of the convex portion, it is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less.

  Examples of the pH adjuster include acidic compounds, alkali compounds, and salts thereof. The salt of the acidic compound is preferably at least one selected from alkali metal salts, ammonium salts, and amine salts, and more preferably ammonium salts. When the basic compound takes a salt form, the counter ion is preferably at least one selected from hydroxide ions, chloride ions and iodide ions, more preferably hydroxide ions and chloride ions. Is at least one selected from

  Examples of the acidic compound include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid; organic acids such as acetic acid, oxalic acid, citric acid, and malic acid; Among these, from the viewpoint of versatility, at least one selected from hydrochloric acid, nitric acid and acetic acid is preferable, and at least one selected from hydrochloric acid and acetic acid is more preferable.

  Examples of the alkali compound include inorganic alkali compounds such as ammonia and potassium hydroxide; organic alkali compounds such as alkylamine and alkanolamine; and the like. Among these, from the viewpoint of improving the quality of the semiconductor substrate, at least one selected from ammonia and alkylamine is preferable, and ammonia is more preferable.

  Examples of the polishing aid other than the polymer B include anionic surfactants and nonionic surfactants. Examples of the anionic surfactant include alkyl ether acetates, alkyl ether phosphates, and alkyl ether sulfates. Examples of nonionic surfactants include nonionic polymers such as polyacrylamide, polyoxyalkylene alkyl ethers, and the like. The polishing aid may be a branched polymer or a crosslinked polymer, but the polishing liquid composition of the present invention includes a branched polymer and a polishing polymer from the viewpoint of suppressing the polishing of the concave portion and improving the polishing rate of the convex portion. It is preferable not to contain a crosslinked polymer.

[Polishing liquid composition]
The polishing liquid composition of the present invention can be produced by a production method including a step of blending a slurry containing particles A and water, a polymer B, and, if necessary, other optional components by a known method. For example, the polishing composition according to the present invention comprises a slurry containing particles A and water, a polymer aqueous solution containing polymer B and water, and other optional components as necessary. . In the present invention, “mixing” includes mixing the particles A, the polymer B and water, and other optional components as necessary, simultaneously or sequentially. The order of mixing is not particularly limited. The said mixing | blending can be performed using mixers, such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill, for example. The compounding quantity of each component in the manufacturing method of the polishing liquid composition of this invention can be made the same as content of each component in the polishing liquid composition of this invention mentioned above.

  The embodiment of the polishing composition of the present invention may be a so-called one-component type that is supplied to the market in a state where all components are premixed, or a so-called two-component type that is mixed at the time of use. There may be. The two-component type polishing liquid composition is divided into a first liquid and a second liquid. The polishing liquid composition includes, for example, a first liquid in which particles A are mixed in water, and a polymer B in water. It may be composed of a dissolved second liquid, and the first liquid and the second liquid may be mixed. The first liquid and the second liquid may be mixed before being supplied to the surface to be polished, or they may be separately supplied and mixed on the surface of the substrate to be polished.

  The pH of the polishing composition of the present invention is preferably 2.5 or more, more preferably 3.0 or more, still more preferably 3.5 or more, from the viewpoint of suppressing polishing of the concave portions and improving the polishing rate of the convex portions. More preferably 4.0 or more, still more preferably 5.5 or more, and preferably 9.5 or less, more preferably 8.0 or less, and still more preferably 7.5 or less. In this invention, pH of polishing liquid composition is a value in 25 degreeC, Comprising: It is the value measured using the pH meter. Specifically, the pH of the polishing composition of the present invention can be measured by the method described in Examples.

  The “content of each component in the polishing composition” of the present invention refers to the content of each component at the time when the polishing composition is used for polishing. The polishing composition of the present invention may be stored and supplied in a concentrated state as long as its stability is not impaired. In this case, it is preferable in that the production / transport cost can be reduced. This concentrated liquid can be appropriately diluted with the above-mentioned aqueous medium as necessary and used in the polishing step. The dilution ratio is preferably 5 to 100 times.

[Polished film]
Examples of the film to be polished by the polishing liquid composition of the present invention include a silicon oxide film. The polishing composition of the present invention can be suitably used for manufacturing a three-dimensional semiconductor device such as a three-dimensional NAND flash memory in which recording elements are three-dimensionally arranged.

[Polishing liquid kit]
The present invention is a polishing liquid kit for producing a polishing liquid composition, the polishing liquid kit comprising an aqueous dispersion of particles A (first liquid) housed in a container, and the particles A water contained in the container. A polishing liquid kit (which contains the aqueous solution of the polymer B (second liquid) housed in a container different from the dispersion liquid and is not mixed with each other, and these are mixed at the time of use. Two-component polishing composition). ADVANTAGE OF THE INVENTION According to this invention, the polishing liquid kit which can obtain the polishing liquid composition which can suppress the grinding | polishing of a recessed part and can improve the polishing rate of a convex part can be provided. Each of the first liquid and the second liquid may contain the above-mentioned [other components] as optional components as necessary.

  The content of each component in the first liquid and the second liquid is a preferable content in the polishing liquid composition when the polishing liquid composition is used for polishing when the first liquid and the second liquid are mixed. It may be set so that when the first liquid, the second liquid, and water are mixed, a preferable content in the polishing liquid composition when the polishing liquid composition is used for polishing is obtained. It may be set.

[Recess protection liquid]
The present invention relates to a recess protecting liquid that is used together with an aqueous dispersion of particles A of the polishing liquid kit and includes water and a polymer B dissolved in water. The concave portion protecting liquid may contain the above-mentioned [other components] as an optional component as necessary. The concave portion protective liquid is mixed with an aqueous dispersion of particles A supplied separately from the concave portion protective liquid at the time of use, and water and an optional component are mixed as necessary, thereby suppressing the polishing of the concave portion and the convex portion. A polishing liquid composition capable of improving the polishing rate is obtained.

  The content of the polymer B in the recess protecting liquid is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and further preferably 0.03% by mass from the viewpoint of concentrating the recess protecting liquid. From the viewpoint of ease of handling when mixing the polishing liquid, it is preferably 30% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass or less.

[Method for Manufacturing Semiconductor Device]
The present invention includes a step of polishing a concavo-convex step surface of a film to be polished using the polishing liquid composition of the present invention (hereinafter also referred to as “polishing step using the polishing liquid composition of the present invention”). The present invention relates to a method for manufacturing an apparatus (hereinafter also referred to as “method for manufacturing a semiconductor substrate of the present invention”). According to the method for manufacturing a semiconductor device of the present invention, it is possible to suppress the polishing of the concave portions and improve the polishing rate of the convex portions, so that an effect of efficiently manufacturing a semiconductor device with improved quality can be achieved.

  The uneven surface of the film to be polished may be naturally formed corresponding to the uneven surface of the lower layer of the film to be polished, for example, when the film to be polished is formed by a method such as chemical vapor deposition. It may also be obtained by forming a concavo-convex pattern using a lithography method or the like.

  The material of the film to be polished preferably contains silicon, more preferably contains at least one selected from the group consisting of silicon oxide, silicon nitride and polysilicon, and contains silicon oxide. And more preferred.

  A specific example of the method for manufacturing a semiconductor device of the present invention is a method for manufacturing a semiconductor recording device in which recording elements are three-dimensionally arranged. A semiconductor recording device manufactured by the manufacturing method includes a plurality of first recording elements arranged in a plane direction apart from each other, and arranged above the first recording elements and arranged in the same direction as the plane direction apart from each other. A plurality of second recording elements, and an insulating film disposed between the first recording element and the second recording element. In the manufacturing method of the semiconductor device, the insulating film is, for example, a silicon oxide film, and is formed by, for example, a CVD method using silane gas and oxygen gas. Since the plurality of first recording elements are formed apart from each other, the formation of the silicon oxide film fills the space between the adjacent first recording elements with the silicon oxide of the silicon oxide film. The surface opposite to the surface on the one recording element side has an uneven step formed corresponding to the unevenness of the lower layer. In the method for manufacturing a semiconductor recording device of the present invention, as the “polishing process using the polishing composition of the present invention”, the silicon oxide film is flattened on the surface opposite to the first recording element side by CMP. Polish until The polishing composition of the present invention can be suitably used in the step of polishing by this CMP method. The width of the protrusion formed corresponding to the unevenness of the lower layer of the silicon oxide film is, for example, not less than 0.5 μm and not more than 5000 μm, preferably not less than 10 μm and not more than 3500 μm. It is 5 μm or more and 10,000 μm or less, preferably 10 μm or more and 6000 μm or less.

In the polishing step using the polishing composition of the present invention, the polishing pad has a rotation speed of, for example, 30 to 200 r / min, and the rotation speed of the substrate to be polished is, for example, 130 to 200 r / min, and the polishing pad is provided. The polishing load set in the polishing apparatus can be set to, for example, 20 to 500 g weight / cm ² , and the supply rate of the polishing composition can be set to, for example, 10 to 500 mL / min or less.

  In the polishing step using the polishing composition of the present invention, the polishing time is preferably 10 seconds or more, more preferably 20 seconds or more from the viewpoint of ensuring flatness, and preferably from the viewpoint of improving productivity. Is 5 minutes or less, more preferably 3 minutes or less, and even more preferably 2 minutes or less.

  In the polishing process using the polishing composition of the present invention, conventionally known materials can be used for the polishing pad used. Examples of the material of the polishing pad include organic polymer foams such as hard foamed polyurethane and non-foamed foams, among which hard foamed polyurethane is preferable.

From the viewpoint of improving the polishing rate, the supply rate of the polishing liquid composition is preferably 0.01 g / min or more per 1 cm ^{2 of} the uneven surface, more preferably 0.1 g / min or more. From the viewpoint of facilitating the treatment, it is preferably 10 g / min or less per 1 cm ^{2 of} the uneven surface, more preferably 5 g / min or less.

[Polishing uneven surface]
The present invention relates to a method for polishing an uneven surface including a polishing step using the polishing composition of the present invention (hereinafter also referred to as the polishing method of the present invention).

  By using the polishing method of the present invention, it is possible to improve the polishing rate of the convex portion while suppressing the polishing of the concave portion, so that the productivity of the semiconductor device with improved quality can be improved. The specific polishing method and conditions can be the same as those of the semiconductor device manufacturing method of the present invention described above.

1. Preparation of Polishing Liquid Composition Water, abrasive grains, and a water-soluble polymer were mixed so as to have the contents shown in Table 1 below to obtain polishing liquid compositions of Examples 1 to 14 and Comparative Examples 1 to 9. The pH of the polishing composition was adjusted using a 1N hydrochloric acid aqueous solution or a 1N ammonium aqueous solution. The pH at 25 ° C. of the polishing liquid compositions of Examples 1 to 14 and Comparative Examples 1 to 9 is as shown in Table 1.

The following particles were used as the abrasive grains.
Particle A1: Average primary particle size 81.7 nm, BET specific surface area 10.2 m ² / g
Particle A2: average primary particle size 68.3 nm, BET specific surface area 12.2 m ² / g
Particle A3: average primary particle size 24.4 nm, BET specific surface area 34.2 m ² / g
Particle A4: average primary particle size 89.4 nm, BET specific surface area 30.5 m ² / g

The following compounds were used as the water-soluble polymer.
Polymer B1: Linear sodium polyacrylate (Aronbis SX weight average molecular weight 5 million manufactured by Toagosei Co., Ltd.)
・ Polymer B2: Linear sodium polyacrylate (Aronbis MX weight average molecular weight 2.5 million manufactured by Toa Gosei)
・ Polymer B3: Linear polyacrylic acid (polysciences weight average molecular weight: 4 million)
-Polymer B4: Polyvinylpyrrolidone (Pitscol K-120L manufactured by Daiichi Kogyo Seiyaku Co., Ltd., weight average molecular weight 2.8 million)
Polymer B5: Linear sodium polyacrylate (TK-75 weight average molecular weight 20,000 manufactured by Kao Corporation)
-Polymer B6: linear sodium polyacrylate (manufactured by Wako Pure Chemical Industries, Ltd., weight average molecular weight 1 million)
Polymer B7: polyacrylamide (manufactured by Polysciences, weight average molecular weight 600,000 to 1,000,000)
Polymer B8: poly (2-acrylamido-2-methylpropanesulfonic acid) (Aldrich's weight average molecular weight 2 million)
-Polymer B9: Polyethylene glycol (Wako Pure Chemical Industries, Ltd., weight average molecular weight 2 million)
-Polymer B10: Cross-linked polyacrylic acid (260H weight average molecular weight 5 million manufactured by Toagosei)

  The average primary particle size and BET specific surface area of the abrasive grains were measured by the following methods.

(A) Measurement of pH of polishing liquid composition The pH value at 25 ° C of the polishing liquid composition is a value measured using a pH meter (Toa Denki Kogyo Co., Ltd., HM-30G). It is a numerical value 1 minute after immersion in the water.

(B) Average primary particle size of abrasive grains The average primary particle size (nm) of abrasive grains is determined by using the specific surface area S (m ² / g) obtained by the following BET (nitrogen adsorption) method, and the true density of ceria particles. The calculation was performed under the condition of 7.2 g / cm ³ and the true density of the silica particles was 2.2 g / cm ³ .

(C) Measuring method of BET specific surface area of abrasive grains The specific surface area was obtained by subjecting an aqueous dispersion of abrasive grains to hot air drying at 120 ° C for 3 hours, and then finely pulverizing them in an agate mortar. Immediately before the measurement, the sample was dried for 15 minutes in an atmosphere of 120 ° C., and then measured by a nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritic automatic specific surface area measuring device Flowsorb III 2305, manufactured by Shimadzu Corporation).

2. Evaluation of polishing composition (Examples 1 to 14, Comparative Examples 1 to 9) [Evaluation Sample]
A commercially available wafer for CMP characteristic evaluation (diameter 300 mm) was prepared as an evaluation sample, and the substrate was cut into 40 mm × 40 mm for polishing evaluation. In this sample for evaluation, a silicon oxide film with a film thickness of 4300 nm is arranged as a convex part on a silicon substrate, and a silicon oxide film with a film thickness of 4300 nm is similarly arranged in the concave part, and the step between the convex part and the concave part is 3400 nm. Thus, a linear uneven pattern is formed by etching. The silicon oxide film is formed by HDP-CVD (High Density Plasma Chemical Vapor Deposition), and has a convex part width of 3000 μm and a concave part width of 5000 μm.

[Polishing conditions]
Polishing tester: single-sided polishing machine (TR15M-TRK1, manufactured by Technorise, surface plate diameter 38 cm)
Polishing pad: Part No. IC-1000 / Suba400 (made by Nitta Haas Co., Ltd.)
Surface plate rotation speed: 100 rpm
Head rotation speed: 110 rpm (Rotation direction is the same as the surface plate)
Polishing load: 300 g weight / cm ²
Polishing liquid supply amount: 50 mL / min (3.125 g / (cm ² · min))
Polishing time: The remaining film thickness of the convex part was measured every 1 minute by the method described later, and polishing was carried out until the residual film thickness reached 900 nm (corresponding to the polishing amount of the convex part of 3400 nm) ± 5 nm or less.

[Measurement of polishing rate of convex part of silicon oxide film]
Using the polishing composition shown in Table 1, the sample for evaluation was polished under the above polishing conditions. After polishing, the substrate was washed with ultrapure water and dried, and the oxide film test piece was used as a measurement object by an optical interference type film thickness measuring device described later. About the sample for evaluation after grinding | polishing, the residual film thickness of a convex part was measured using the optical interference type film thickness meter (Brand name: VM-1230, Co., Ltd. product made from SCREEN Semiconductor Solutions).

Before and after polishing, the thickness of the oxide film was measured using an optical interference type film thickness measuring device (trade name: VM-1200, manufactured by SCREEN Semiconductor Solutions Co., Ltd.). The polishing rate of the oxide film was calculated by the following formula, and the polishing rate when the polishing liquid composition of Comparative Example 1 was used was set to 100 and shown in Table 1 below.
Polishing rate of oxide film (nm / min)
= [Oxide film thickness before polishing (nm)-Oxide film thickness after polishing (nm)] / Polishing time (min)

[Measurement of excessive polishing amount of recesses in silicon oxide film]
For the sample for evaluation after polishing polished under the above polishing conditions, the remaining film thickness of the recess was measured using an optical interference film thickness meter (trade name: VM-1230, manufactured by SCREEN Semiconductor Solutions Co., Ltd.). The difference (nm) between the film thickness before polishing (4300 nm) and the film thickness of the recesses after polishing is calculated as an excessive polishing amount, and the case where the polishing liquid composition of Comparative Example 1 is used as 100 is shown in Table 1 below. It was shown to. The excess polishing amount was judged based on the following criteria. If the determination is A or B, the excessive polishing amount is sufficiently small.
A: Excess polishing amount is 500 nm or less B: Excess polishing amount exceeds 500 nm and 550 nm or less C: Excess polishing amount exceeds 550 nm and 600 nm or less D: Excess polishing amount exceeds 600 nm

[Relationship between normal stress and shear stress]
A 0.1% by weight aqueous solution of the water-soluble polymer used in the preparation of the polishing liquid compositions of Examples 2 and 6 and Comparative Examples 1 and 6 was adjusted to pH 6.0 with hydrochloric acid or ammonia (aqueous solution temperature 25 ° C. ) Was prepared, and measurement was performed in an environment of 25 ° C. and 50% RH using a viscoelasticity measuring apparatus (manufactured by Anton Paar, Physica MCR301). After using a parallel plate (PP75, φ75 mm) to increase the shear rate from 1 to 10,000 (1 / s) at a gap of 100 μm, then decrease the shear rate from 10000 to 1 (1 / s) to the shear rate. The normal stress was measured, and the results when the shear rate was increased are shown in FIGS. Table 2 shows the normal stress when the shear rate is 534 (1 / s) and 8500 (1 / s) when the shear rate is increased.

  As shown in Table 1, the polishing liquid compositions of Examples 1 to 14 are higher in the polishing rate of the convex portions than the polishing liquid compositions of Comparative Examples 1 to 9, and the polishing of the concave portions is suppressed. The flatness was also good.

  As shown in Table 2 and FIGS. 1 to 2, the aqueous solutions of the water-soluble polymers B1 and B3 used for the preparation of the polishing liquid compositions of Examples 2 and 6 were positive as the shear rate increased. Normal stress and negative normal stress were expressed in this order. On the other hand, as shown in Table 2 and FIGS. 3 to 4, the aqueous solutions of the water-soluble polymers B5 and B10 used for the preparation of the polishing liquid compositions of Comparative Examples 1 and 6 have a shear rate of 534 (1 / s). , 8500 (1 / s), the normal stress was negative.

  As described above, the polishing composition according to the present disclosure is useful in a method for manufacturing a semiconductor device for high density or high integration.

Claims (11)

A polishing composition for a silicon oxide film comprising particles A, at least part of which is made of ceria, a water-soluble polymer B, and water,
The water-soluble polymer B is a linear polymer and includes one or more structural units selected from a structural unit derived from acrylic acid, a structural unit derived from acrylate, and a structural unit derived from vinylpyrrolidone. A polishing composition for a silicon oxide film having a weight average molecular weight of 2.5 million or more.   The water-soluble polymer B concentration 0.1% by mass aqueous solution having an aqueous solution temperature of 25 ° C. and a pH of 6.0 exhibits both positive normal stress and negative normal stress in this order due to an increase in shear rate. The polishing liquid composition according to 1.   The polishing composition according to claim 1 or 2, wherein the content of the water-soluble polymer B is 0.005 mass% or more and 0.15 mass% or less.   4. The particle A according to claim 1, wherein the particle A is at least one selected from pulverized ceria particles Aa, colloidal ceria particles Ab, and particles Ac in which ceria is coated on particles other than ceria. 5. Polishing liquid composition.   The polishing liquid composition according to any one of claims 1 to 4, wherein the content of the particles A is 0.1 mass% or more and 10 mass% or less.   The polishing composition according to any one of claims 1 to 5, wherein the pH at 25 ° C is from 2.5 to 9.5. A polishing liquid kit for producing a polishing liquid composition,
A first liquid in which an aqueous dispersion of particles A, the surface of which is at least partly made of ceria, is stored in a container;
An aqueous solution of the water-soluble polymer B includes a second liquid stored in a container different from the container in which the first liquid is stored;
The water-soluble polymer B is a linear polymer and includes one or more structural units selected from a structural unit derived from acrylic acid, a structural unit derived from acrylate, and a structural unit derived from vinylpyrrolidone. Polishing liquid kit whose weight average molecular weight is 2.5 million or more. A recess-protecting liquid used together with an aqueous dispersion of particles A, the surface of which is at least partly composed of ceria,
Water and water-soluble polymer B dissolved in the water,
The water-soluble polymer B is a linear polymer and includes one or more structural units selected from a structural unit derived from acrylic acid, a structural unit derived from acrylate, and a structural unit derived from vinylpyrrolidone. A recess-protecting liquid having a weight average molecular weight of 2.5 million or more.   A method for manufacturing a semiconductor device, comprising a step of polishing an uneven step surface of a silicon oxide film using the polishing liquid composition according to claim 1. The semiconductor device is a semiconductor memory device in which recording elements are arranged three-dimensionally,
Including the step of forming the silicon oxide film so as to cover between the recording elements adjacent in the horizontal direction and the recording elements,
The method for manufacturing a semiconductor substrate according to claim 9, wherein the uneven step surface of the silicon oxide film formed in the step has an uneven step corresponding to the unevenness of the surface covered with the silicon oxide film.   A step of polishing an uneven step surface of the silicon oxide film using the polishing composition according to any one of claims 1 to 6, wherein the silicon oxide film is formed in a manufacturing process of a semiconductor device. A method for polishing an uneven step surface, which is an insulating film.

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