JP6811090B2 - Abrasive liquid composition for silicon oxide film - Google Patents

Description

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

Chemical mechanical polishing (CMP) technology is a method in which the surface of the substrate to be polished and the polishing pad are in contact with each other, and the polishing liquid is supplied to these contact points while the substrate to be polished and the polishing pad are relatively. This is a technique for chemically reacting the surface uneven portion of the substrate to be polished and mechanically removing it to flatten it by moving it.

At present, in the manufacturing process of semiconductor devices, when flattening the interlayer insulating film, forming a shallow trench element separation structure (hereinafter, also referred to as "element separation structure"), forming a plug and an embedded metal wiring, etc. CMP technology has become an indispensable technology. In recent years, the number of layers and high definition of semiconductor elements has dramatically increased, and it has become desired to be able to polish at high speed while having better flatness.

Patent Document 1 describes 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 flatness performance. Aqueous slurry compositions for polishing are disclosed. The polyacrylic acid contained in the aqueous slurry composition disclosed in Patent Document 1 is a crosslinked polyacrylic acid. In Patent Document 2, for the purpose of high flattening, for polishing an Al—Cu alloy containing, for example, polyacrylic acid having a weight average molecular weight of 2000 as a polymer electrolyte exhibiting a normal stress effect. The slurry is disclosed. Patent Document 3 discloses an abrasive containing an ammonium polyacrylate salt having a molecular weight of 15,000 as an abrasive applicable to shallow trench separation. Patent Document 4 discloses an aqueous dispersion for CMP containing colloidal silica as abrasive grains and polyvinylpyrrolidone having a weight average molecular weight of more than 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, colloidal silica is contained as abrasive grains, and poly (meth) acrylic acid and two or more other carbonyl groups are contained. An aqueous dispersion for CMP containing an organic acid is disclosed.

Japanese Unexamined Patent Publication No. 2006-128689 Japanese Unexamined Patent Publication No. 10-168431 Japanese Unexamined Patent Publication No. 2000-160136 JP-A-2007-88424 JP-A-2009-27142

Cerium oxide (hereinafter, also referred to as “ceria”) particles are generally used as the abrasive grains used for polishing the silicon oxide film, and are obtained by firing and pulverizing a cerium compound such as cerium carbonate or cerium nitrate, for example. Cerium particles of various shapes and sizes (hereinafter, also referred to as "atypical ceria") such as calcined crushed ceria are widely used. However, when the polishing liquid composition containing the ceria particles and the water-soluble polymer is used for flattening a silicon oxide film having an uneven stepped surface and a relatively wide convex portion, the concave portion is polished. Although it can be suppressed, the problem is that the polishing speed of the convex portion is significantly reduced.

The present invention provides a polishing liquid composition for a silicon oxide film capable of improving the polishing speed of convex portions while suppressing polishing of concave portions, a method for manufacturing and polishing a semiconductor substrate using the same, and a concave protective liquid and a polishing liquid. Provide a kit.

The polishing liquid composition for a silicon oxide film of the present invention is a polishing liquid composition for a silicon oxide film containing particles A having at least a part of the surface made of ceria, a water-soluble polymer B, and water. ,
The water-soluble polymer B is a linear polymer and contains 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.

The polishing liquid kit for producing the polishing liquid composition for a silicon oxide film of the present invention is highly water-soluble with the first liquid in which an aqueous dispersion of particles A having at least a part of the surface made of ceria is stored in a container. The aqueous solution of the molecule B contains 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. It contains one or more structural units selected from units, structural units derived from acrylate and structural units derived from vinylpyrrolidone, and has a weight average molecular weight of 2.5 million or more.

The recess protective solution of the present invention is a recess protective solution used together with an aqueous dispersion of particles A having at least a part of the surface made of ceria, and is composed of water and a water-soluble polymer B dissolved in the water. The water-soluble polymer B is a linear polymer, and is one or more constituents selected from a structural unit derived from acrylic acid, a structural unit derived from acrylate, and a structural unit derived from vinylpyrrolidone. Including units, the weight average molecular weight is 2.5 million or more.

The method for manufacturing a semiconductor device of the present invention includes a step of polishing an uneven stepped surface of a silicon oxide film by using the polishing liquid composition for a silicon oxide film of the present invention.

The method for polishing the uneven stepped surface of the present invention includes a step of polishing the uneven stepped surface of the silicon oxide film using the polishing liquid composition for a silicon oxide film of the present invention, and 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 speed of convex portions while suppressing polishing of concave portions, a method for manufacturing and polishing a semiconductor substrate using the same, and a concave protective liquid and a concave protective liquid. A polishing liquid kit is provided.

FIG. 1 is a graph showing the relationship between the shear rate applied to the 0.1 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 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 mass% water-soluble polymer B10 aqueous solution and the normal stress.

As a result of diligent studies by the present inventors, in an abrasive liquid composition containing particles in which at least a part of the surface is composed of ceria as abrasive grains, it is a linear polymer and is a structural unit derived from acrylic acid, acrylate. Polishing of silicon oxide film when a water-soluble polymer containing one or more structural units selected from the structural units derived from and vinylpyrrolidone and having a weight average molecular weight of 2.5 million or more is contained. It is based on the finding that it is possible to improve the polishing speed of the convex portion while suppressing the polishing of the concave portion when used in.

The reason why when the uneven stepped surface of the silicon oxide film is polished using the polishing liquid composition of the present invention, the effect that the polishing speed of the convex portion can be improved while suppressing the polishing of the concave portion can be obtained. It is not clear, but 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. However, this polyacrylic acid can be obtained by increasing the amount of polymer added. , The effect of suppressing concave polishing has been improved. However, if the amount of the polymer added is increased in order to improve the effect of suppressing the polishing of the concave portion, the polishing speed of the convex portion is lowered, and the polishing speed of the convex portion is remarkable particularly when the width of the convex portion is relatively wide. The problem was to reduce the rate. On the other hand, in the polishing liquid composition of the present invention, as a concave polishing inhibitor, it is a linear polymer, a structural unit derived from acrylic acid, a structural unit derived from acrylate, and a configuration derived from vinylpyrrolidone. By using a water-soluble polymer containing one or more constituent units selected from the units and having a weight average molecular weight of 2.5 million or more, the concave polishing inhibitor is thin and uniform with respect to the uneven stepped surface of the silicon oxide film. It is presumed that the protective layer can be formed, and both the high polishing speed of the convex portion and the polishing suppression of the concave portion can be achieved at the same time.

[Particle A whose surface is at least partly made of ceria]
The polishing liquid composition of the present invention contains particles A (hereinafter, may be abbreviated as "particles A") in which at least a part of the surface is composed of ceria as polishing abrasive grains. The particles A are preferably other than crushed ceria particles Aa (hereinafter sometimes abbreviated as "particles Aa"), colloidal ceria particles Ab (hereinafter sometimes abbreviated as "particles Ab"), and ceria. One or more selected from particle Ac (hereinafter, may be abbreviated as "particle Ac") in which ceria is coated on the particles.

Particles Aa can be obtained by firing and pulverizing a cerium compound such as cerium carbonate or cerium nitrate. Particle Ab can be obtained by a build-up process, for example, by the method described in Examples 1 to 4 of JP-A-2010-505735. Examples of the particle 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, and the composite particles deposit ceria on the silica particles, for example. Can be obtained by The ceria-coated silica particles can be obtained, for example, by the method described in Examples 1 to 14 of JP2015-63451 or Examples 1 to 4 of JP2013-119131. 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 residues after polishing.

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

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

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

[Water-soluble polymer B]
The polishing liquid 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 speed of convex portions, and is derived from acrylate, which is a structural unit derived from acrylic acid. A water-soluble polymer B (hereinafter, may be abbreviated as “polymer B”) having a weight average molecular weight of 2.5 million or more and containing one or more structural units selected from the structural units of the above and the structural units derived from vinylpyrrolidone. .)including. A 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.

As the polymer B, anionic groups such as a carboxylic acid group may take the form of a neutralized salt. Examples of the counterion when the anionic group takes the form of a salt include metal ion, ammonium ion, alkylammonium ion and the like, and ammonium ion is preferable from the viewpoint of improving the quality of the semiconductor substrate. The polymer B in the form of an ammonium salt is prepared by, for example, mixing the polymer B in the form of a metal salt such as Na salt, a cation exchange resin, and water, stirring for a predetermined time, and then filtering the cation exchange resin. It is obtained by ion exchange between metal ions and hydrogen ions and then neutralizing with ammonia.

The polymer B is, for example, polyacrylic acid, polyvinylpyrrolidone, a copolymer of acrylic acid and monomethoxypolyethylene glycol mono (meth) acrylate, alkali metal salts thereof, and at least one selected from ammonium salts 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 from the same viewpoint, from the viewpoint of suppressing the polishing of the concave portion and improving the polishing speed of the convex portion. It is preferably 10 million or less, more preferably 8 million or less, still more preferably 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 Refractometer Detector Column: G4000PWXL and G2500PWXL manufactured by Tosoh Corporation were connected in series.
Eluent: 0.2 M phosphate buffer / acetonitrile = 90/10 (volume ratio) adjusted to a concentration of 0.5 g / 100 mL, and 20 μL was used.
Column temperature: 40 ° C
Flow velocity: 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 speed of the convex portion, the polymer B has a shear rate with the shear rate applied to a 0.1 mass% aqueous solution (aqueous solution 25 ° C.) of the pH 6.0 of the polymer B as the horizontal axis. In a graph whose vertical axis is the normal stress acting on the liquid surface of the aqueous solution when is 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 preferable. From the same viewpoint, the normal stress is preferably a positive value when the shear rate X (1 / s) and a negative value when the shear rate Y (1 / s). However, the shear rate Y (1 / s) is a value larger than the shear rate X (1 / s). The shear rate X (1 / s) is preferably a value in the range of 0 to 3000 (1 / s), more preferably 10 to 2500 (1 / s), and further 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 further preferably 8500 (1 / s). is there.

The content of the polymer B in the polishing liquid 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 portion and improving the polishing speed of the convex portion. It is more preferably 0.03% by mass or more, and preferably 0.15% by mass or less, more preferably 0.10% by mass or less, still more preferably 0.06% by mass or less.

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

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

[Other ingredients]
The polishing liquid composition of the present invention may contain other components as long as the effects of suppressing the polishing of the concave portion and improving the polishing speed of the convex portion are not impaired. Examples of other components include pH adjusters, polishing aids other than compound B, and the like. Further, examples of other components include thickeners, dispersants, rust preventives, basic substances, polishing rate improvers, surfactants, polymer compounds other than polymer B, and the like. The content of these optional components is preferably 0.001% by mass or more, more preferably 0.0025% by mass or more, further preferably 0.01% by mass or more, and suppresses polishing of recesses, from the viewpoint of ensuring the polishing rate. From the viewpoint of improving the polishing speed of the convex portion, 1% by mass or less is preferable, 0.5% by mass or less is more preferable, and 0.1% by mass or less is further preferable.

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

Examples of the acidic compound include inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid; and organic acids such as acetic acid, oxalic acid, citric acid and malic acid; Among them, 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 alkaline compound include inorganic alkaline compounds such as ammonia and potassium hydroxide; and organic alkaline compounds such as alkylamine and alkanolamine; Among them, at least one selected from ammonia and alkylamine is preferable, and ammonia is more preferable, from the viewpoint of improving the quality of the semiconductor substrate.

Examples of the polishing aid other than the polymer B include anionic surfactants and nonionic surfactants. Examples of the anionic surfactant include alkyl ether acetate, alkyl ether phosphate, and alkyl ether sulfate. Examples of the nonionic surfactant include nonionic polymers such as polyacrylamide and polyoxyalkylene alkyl ethers. The polishing aid may be a branched polymer or a crosslinked polymer, but the polishing liquid composition of the present invention contains the branched polymer and the polishing aid from the viewpoint of suppressing the polishing of the concave portion and improving the polishing speed of the convex portion. It is preferable that it does not contain a crosslinked polymer.

[Abrasive 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 liquid composition according to the present invention is formed by blending 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, "blending" includes mixing particles A, polymer B and water, and, if necessary, other optional components simultaneously or in sequence. The order of mixing is not particularly limited. The formulation can be carried out using, for example, a mixer such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. The blending amount of each component in the method for producing the polishing liquid composition of the present invention can be the same as the content of each component in the polishing liquid composition of the present invention described above.

The embodiment of the polishing liquid composition of the present invention may be a so-called one-component type in which all the components are premixed and supplied to the market, or a so-called two-component type in which all the components are mixed at the time of use. There may be. The two-component polishing liquid composition is divided into a first liquid and a second liquid. In the polishing liquid composition, for example, the first liquid in which the particles A are mixed with water and the 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 supplied separately and mixed on the surface of the substrate to be polished.

The pH of the polishing liquid 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 portion and improving the polishing speed of the convex portion. More preferably 4.0 or more, even more preferably 5.5 or more, and preferably 9.5 or less, more preferably 8.0 or less, still more preferably 7.5 or less. In the present invention, the pH of the polishing liquid composition is a value at 25 ° C., which is a value measured using a pH meter. Specifically, the pH of the polishing liquid composition of the present invention can be measured by the method described in Examples.

The "content of each component in the polishing liquid composition" of the present invention means the content of each component at the time when the polishing liquid composition is used for polishing. The polishing liquid 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 manufacturing / transportation cost can be reduced. Then, this concentrated solution can be appropriately diluted with the above-mentioned aqueous medium and used in the polishing step, if necessary. The dilution ratio is preferably 5 to 100 times.

[Film to be polished]
Examples of the film to be polished to which the polishing liquid composition of the present invention is polished include a silicon oxide film. The polishing liquid 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 arranged three-dimensionally.

[Abrasive liquid kit]
The present invention is a polishing liquid kit for producing a polishing liquid composition, and the polishing liquid kit includes an aqueous dispersion liquid (first liquid) of particles A stored in a container and the particle A water in the container. A polishing liquid kit (second liquid) containing the aqueous solution of the polymer B (second liquid) stored in a container separate from the dispersion liquid and stored in a state where they are not mixed with each other, and these are mixed at the time of use. Two-component polishing liquid composition). According to the present invention, it is possible to provide a polishing liquid kit capable of obtaining a polishing liquid composition capable of suppressing polishing of concave portions and improving the polishing speed of convex portions. The first liquid and the second liquid may each contain the above-mentioned [other components] as optional components, if necessary.

The content of each component in the first liquid and the second liquid is the preferable content in the polishing liquid composition at the time when the polishing liquid composition is used for polishing when the first liquid and the second liquid are mixed. When the first liquid, the second liquid, and water are mixed, the content in the polishing liquid composition at the time when the polishing liquid composition is used for polishing is set to be preferable. It may be set.

[Recess protective liquid]
The present invention relates to a recess protective solution that is used together with an aqueous dispersion of particles A of the polishing solution kit and contains water and a polymer B dissolved in water. The recess protective liquid may contain the above-mentioned [other components] as an optional component, if necessary. The concave protective liquid is mixed with the aqueous dispersion of particles A, which is supplied separately from the concave protective liquid, at the time of use, and water or an arbitrary component is mixed as necessary to suppress polishing of the concave portion and to suppress the polishing of the convex portion. A polishing liquid composition capable of improving the polishing speed can be obtained.

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

[Manufacturing method of semiconductor devices]
The present invention is a semiconductor including a step of polishing an uneven stepped surface of a film to be polished using the polishing liquid composition of the present invention (hereinafter, also referred to as a “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 “a 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 polishing of concave portions and improve the polishing speed of convex portions, so that it is possible to efficiently manufacture a semiconductor device with improved quality.

The uneven stepped surface of the film to be polished may be naturally formed corresponding to the uneven step 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. However, it may 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 at least one selected from the group consisting of silicon oxide, silicon nitride and polysilicon, and preferably contains silicon oxide. And more preferable.

A specific example of the method for manufacturing a semiconductor device of the present invention is, for example, a method for manufacturing a semiconductor recording device in which recording elements are three-dimensionally arranged. The semiconductor recording device manufactured by the manufacturing method includes a plurality of first recording elements arranged apart from each other in the plane direction, and arranged above the first recording element and separated from each other in the same direction as the plane direction. The plurality of second recording elements are provided, and an insulating film arranged between the first recording element and the second recording element is included. In the method for manufacturing 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, due to the formation of the silicon oxide film, the space between the adjacent first recording elements is filled with the silicon oxide of the silicon oxide film, and the silicon oxide film is the first. 1 The opposite surface of the surface on the recording element side has an uneven step formed corresponding to the unevenness of the lower layer. In the method for manufacturing a semiconductor recording apparatus of the present invention, as a "polishing step using the polishing liquid composition of the present invention", the silicon oxide film is flattened on the opposite surface of the surface on the first recording element side by the CMP method. Polish until it becomes. The polishing liquid composition of the present invention can be suitably used in the step of performing polishing by this CMP method. The width of the convex portion formed corresponding to the unevenness of the lower layer of the silicon oxide film is, for example, 0.5 μm or more and 5000 μm or less, preferably 10 μm or more and 3500 μm or less, and the width of the concave portion is, for example, 0. It is 5 μm or more and 10000 μm or less, preferably 10 μm or more and 6000 μm or less.

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

In the polishing step using the polishing liquid 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, still more preferably 2 minutes or less.

As the material of the polishing pad used in the polishing step using the polishing liquid composition of the present invention, conventionally known materials can be used. Examples of the material of the polishing pad include an organic polymer foam such as hard foamed polyurethane and a non-foamed material, and among them, 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, more preferably 0.1 g / min or more per 1 cm ^{2 of} the uneven surface, and reduces the cost and waste liquid. From the viewpoint of facilitating the treatment, it is preferably 10 g / min or less, and more preferably 5 g / min or less per 1 cm ^{2 of} the uneven surface.

[Method of polishing uneven stepped surface]
The present invention relates to a method for polishing an uneven stepped surface (hereinafter, also referred to as the polishing method of the present invention), which includes a polishing step using the polishing liquid composition of the present invention.

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

1. 1. Preparation of Polishing Solution 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 solution compositions of Examples 1 to 14 and Comparative Examples 1 to 9. The pH of the polishing liquid composition was adjusted using a 1N hydrochloric acid aqueous solution or a 1N ammonium aqueous solution. The pH of the polishing liquid compositions of Examples 1 to 14 and Comparative Examples 1 to 9 at 25 ° C. is as shown in Table 1.

The following particles were used as the abrasive particles.
-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 (Alonbis SX weight average molecular weight 5 million manufactured by Toagosei)
-Polymer B2: Linear sodium polyacrylate (Toagosei Aronbis MX weight average molecular weight 2.5 million)
-Polymer B3: Linear polyacrylic acid (manufactured by Polyscience, Inc., weight average molecular weight: 4 million)
Polymer B4: Polyvinylpyrrolidone (Pitzcol K-120L manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., weight average molecular weight 2.8 million)
Polymer B5: Linear sodium polyacrylate (TK-75 manufactured by Kao Corporation, weight average molecular weight 20,000)
Polymer B6: Linear sodium polyacrylate (Wako Pure Chemical Industries, Ltd., weight average molecular weight 1 million)
Polymer B7: Polyacrylamide (manufactured by Polyscience, weight average molecular weight 600,000 to 1,000,000)
Polymer B8: Poly (2-acrylamide-2-methylpropanesulfonic acid) (Aldrich, weight average molecular weight 2 million)
-Polymer B9: Polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., weight average molecular weight 2 million)
Polymer B10: Crosslinked 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) pH measurement of the polishing liquid composition The pH value of the polishing liquid composition at 25 ° C. is a value measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and the polishing liquid composition of the electrode. It is a numerical value 1 minute after immersion in.

(B) Average primary particle size of abrasive grains For the average primary particle size (nm) of abrasive grains, the specific surface area S (m ² / g) obtained by the following BET (nitrogen adsorption) method is used to determine the true density of ceria particles. It was calculated as 7.2 g / cm ³ and the true density of the silica particles was 2.2 g / cm ³ .

(C) Method for Measuring BET Specific Surface Area of Abrasive Grains For the specific surface area, an aqueous dispersion of abrasive grains was dried with hot air at 120 ° C. for 3 hours, and then finely pulverized in an agate mortar to obtain a sample. Immediately before the measurement, the sample was dried in an atmosphere of 120 ° C. for 15 minutes, and then measured by the nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritic automatic specific surface area measuring device Flowsorb III2305, manufactured by Shimadzu Corporation).

2. 2. Evaluation of Abrasive Liquid Compositions (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 a size of 40 mm × 40 mm for polishing evaluation. In this evaluation sample, a silicon oxide film having a film thickness of 4300 nm is arranged as a convex portion on a silicon substrate, and a silicon oxide film having a film thickness of 4300 nm is also arranged in a concave portion, and a step between the convex portion and the concave portion is 3400 nm. As such, 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 portion width of 3000 μm and a concave portion width of 5000 μm.

[Polishing conditions]
Polishing tester: Single-sided polishing machine (Texhnolyze TR15M-TRK1, surface plate diameter 38 cm)
Polishing pad: Part number IC-1000 / Suba400 (manufactured 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
Abrasive liquid supply amount: 50 mL / min (3.125 g / (cm ^2. min))
Polishing time: The residual film thickness of the convex portion was measured every 1 minute by the method described later, and polishing was performed until the residual film thickness was 900 nm (corresponding to the polishing amount of the convex portion of 3400 nm) ± 5 nm or less.

[Measurement of polishing speed of convex parts of silicon oxide film]
Using the polishing liquid composition shown in Table 1, the evaluation sample was polished under the above polishing conditions. After polishing, it was washed with ultrapure water and dried, and the oxide film test piece was used as a measurement target by an optical interference type film thickness measuring device described later. For the evaluation sample after polishing, the residual film thickness of the convex portion was measured using an optical interference type film thickness meter (trade name: VM-1230, manufactured by SCREEN Semiconductor Solutions Co., Ltd.).

Before and after polishing, the film thickness of the oxide film was measured using a light 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 is shown in Table 1 below, assuming that the polishing rate when the polishing solution composition of Comparative Example 1 was used was 100.
Oxide film polishing rate (nm / min)
= [Oxidation film thickness before polishing (nm) -Oxidation film thickness after polishing (nm)] / Polishing time (minutes)

[Measurement of excess polishing amount of recesses of silicon oxide film]
For the evaluation sample after polishing under the above polishing conditions, the residual 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.), and the recess was measured. The difference (nm) between the film thickness before polishing (4300 nm) and the film thickness of the concave portion after polishing is calculated as the excess polishing amount, and the case where the polishing liquid composition of Comparative Example 1 is used is taken as 100, and Table 1 below It was shown to. The amount of excess polishing was judged as good or bad based on the following criteria. If it is judged as A or B, the amount of excessive polishing is sufficiently small.
A: Excessive polishing amount is 500 nm or less B: Excessive polishing amount is more than 500 nm and 550 nm or less C: Overpolishing amount is more than 550 nm and 600 nm or less D: Overpolishing amount is more than 600 nm

[Relationship between normal stress and shear stress]
A 0.1% by mass aqueous solution of the water-soluble polymer used for preparing the polishing solution 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 measured in an environment of 25 ° C. and 50% RH using a viscoelasticity measuring device (PhysicaMCR301 manufactured by AntonioPaar). Using a parallel plate (PP75, φ75 mm), the shear rate is increased from 1 to 10000 (1 / s) with a gap of 100 μm, and then decreased from 10000 to 1 (1 / s) with respect to the shear rate. The normal stress was measured, and the results when the shear rate increased were shown in FIGS. 1 to 4. Table 2 shows the normal stresses when the shear rates are 534 (1 / s) and 8500 (1 / s) when the shear rate is increased.

As shown in Table 1, in the polishing liquid compositions of Examples 1 to 14, the polishing speed of the convex portion is faster than that of the polishing liquid compositions of Comparative Examples 1 to 9, and the polishing of the concave portion is suppressed. The flatness was also good.

As shown in Table 2, FIGS. 1 and 2, the aqueous solutions of the water-soluble polymers B1 and B3 used for preparing the polishing liquid compositions of Examples 2 and 6 became 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, FIGS. 3 to 4, the aqueous solutions of the water-soluble polymers B5 and B10 used for preparing the polishing liquid compositions of Comparative Examples 1 and 6 had a shear rate of 534 (1 / s). , 8500 (1 / s), the normal stress was negative.

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

Claims (10)

A polishing solution composition for a silicon oxide film containing particles A having at least a part of the surface made of ceria, a water-soluble polymer B, and water.
The water-soluble polymer B is a linear polymer and contains 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 liquid composition for a silicon oxide film having a weight average molecular weight of 2.5 million or more. The claim that the aqueous solution having a water-soluble polymer B concentration of 0.1% by mass at an aqueous solution temperature of 25 ° C. and a pH of 6.0 expresses both positive normal stress and negative normal stress in this order as the shear rate increases. The polishing liquid composition according to 1. The polishing liquid composition according to claim 1 or 2, wherein the content of the water-soluble polymer B is 0.005% by mass or more and 0.15% by mass or less. The item according to any one of claims 1 to 3, 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. Abrasive 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% by mass or more and 10% by mass or less. The polishing liquid composition according to any one of claims 1 to 5, wherein the pH at 25 ° C. is 2.5 or more and 9.5 or less. A polishing liquid kit for producing a polishing liquid composition.
The first liquid in which the aqueous dispersion of particles A whose surface is at least partly composed of ceria is stored in a container, and
The aqueous solution of the water-soluble polymer B contains 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 contains 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 liquid kit having a weight average molecular weight of 2.5 million or more. A recess protective solution that is used with an aqueous dispersion of particles A whose surface is at least partly composed of ceria.
It contains water and the water-soluble polymer B dissolved in the water.
The water-soluble polymer B is a linear polymer and contains 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 protective solution having a weight average molecular weight of 2.5 million or more. A method for manufacturing a semiconductor device, which comprises a step of polishing an uneven stepped surface of a silicon oxide film using the polishing liquid composition according to any one of claims 1 to 6. The silicon oxide film is formed in a process of manufacturing a semiconductor device, including a step of polishing the uneven stepped surface of the silicon oxide film using the polishing liquid composition according to any one of claims 1 to 6. A method for polishing uneven stepped surfaces, which is an insulating film.

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