JP2022164423A - Polishing liquid composition for silicon oxide film - Google Patents

Abstract

To provide a polishing liquid composition for silicon oxide films which can improve the polishing rate of a convex portion of a silicon oxide film on a substrate surface (convex removable rate), a method for producing a semiconductor substrate using the same, and a method for polishing a substrate.SOLUTION: This invention relates to a polishing liquid composition for silicon oxide films that contains cerium oxide particles (component A), a heterocyclic aromatic compound (component B), and a water-based medium. The component A has an oxygen storage content of 50 μmol/g or more.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present disclosure relates to a polishing liquid composition for silicon oxide films containing cerium oxide particles, a method for manufacturing a semiconductor substrate using the same, and a method for polishing a substrate.

A chemical mechanical polishing (CMP) technique is a technique in which the surface of a substrate to be polished and a polishing pad are brought into contact with each other, and a polishing liquid is supplied to the contact area between the substrate and the polishing pad. This is a technique for chemically reacting uneven portions on the surface of the substrate to be polished and mechanically removing and flattening the substrate by moving the substrate.

At present, this CMP technology is essential for the planarization of interlayer insulating films, the formation of shallow trench isolation structures, the formation of plugs and embedded metal wiring, etc. in the manufacturing process of semiconductor devices. . 2. Description of the Related Art In recent years, the number of layers of semiconductor elements and the increase in definition thereof have progressed dramatically, and there has been a demand for further improvement in the yield and throughput of semiconductor elements. Accordingly, in the CMP process as well, scratch-free and faster polishing has been desired.

For example, Patent Document 1 proposes a polishing liquid composition for CMP having a pH of about 1 to 6, containing wet ceria particles, a functionalized heterocycle, a pH adjusting agent, and an aqueous monomer. Claims ² and 3, etc. of the same document state that the wet ceria particles have a surface containing ^tridentate hydroxyl groups, It has a surface coverage, a Raman spectrum includes a peak at 458 cm ^-1 and a peak at 583 cm ^-1 , and the ratio of the peak intensity at 458 cm ^-1 to the peak intensity at 583 cm ^-1 is 100 or less. there is

Japanese Patent Application Publication No. 2018-512475

2. Description of the Related Art In recent years, the field of semiconductors has progressed toward higher integration, and wiring has been required to become more complicated and finer. Therefore, in CMP, the grain size of abrasive grains is reduced to reduce defects.
In particular, in the planarization process by CMP of the interlayer insulating film of the three-dimensional NAND type flash memory, there is a step difference in the surface unevenness of the silicon oxide film between the array portion of the film stacked stepwise on the substrate to be polished and its peripheral portion. is large, there is a problem that planarization by CMP takes a long time. For example, in the reference International Conference on Planarization/CMP technology (ICPT), p106 (2016), as shown in FIG. , methods have been proposed to improve CMP efficiency and reduce polishing time. On the other hand, as the recording capacity increases, the thickness of the array portion is further improved, and the unevenness of the surface is further increased. Therefore, it is becoming more and more demanded to remove such fine protrusions at high speed.

Accordingly, the present disclosure provides a polishing liquid composition for a silicon oxide film capable of improving the polishing speed (protrusion elimination speed) of silicon oxide film protrusions on a substrate surface, a method for manufacturing a semiconductor substrate using the same, and a method for polishing a substrate. I will provide a.

In one aspect of the present disclosure, silicon oxide containing cerium oxide particles (component A), a heteroaromatic compound (component B), and an aqueous medium, wherein component A has an oxygen storage capacity of 50 μmol/g or more It relates to a film-polishing liquid composition.

In one aspect, the present disclosure includes a step of polishing a film-to-be-polished using the polishing composition of the present disclosure, wherein the film-to-be-polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate. Regarding the method.

The present disclosure, in one aspect, relates to a method for manufacturing a semiconductor substrate, comprising polishing a film-to-be-polished using the polishing composition described in the present disclosure.

According to one aspect of the present disclosure, it is possible to provide a polishing liquid composition for a silicon oxide film that can improve the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions on the substrate surface.

FIG. 1 is a schematic diagram for explaining an evaluation wafer. FIG. 2 is a schematic diagram for explaining extra etching before CMP of an interlayer insulating film of a three-dimensional NAND flash memory.

In one aspect of the present disclosure, by combining cerium oxide (hereinafter also referred to as “ceria”) particles having a predetermined oxygen storage capacity and a heteroaromatic compound, the polishing rate of the silicon oxide film protrusions on the substrate surface ( It is based on the knowledge that the removal rate of protrusions), for example, the polishing rate of protrusions of a silicon oxide film existing on a substrate after extra etching can be improved.

That is, in one aspect, the present disclosure contains cerium oxide particles (component A), a heteroaromatic compound (component B), and an aqueous medium, and the oxygen storage amount of component A is 50 μmol/g or more. The present invention relates to a polishing liquid composition for silicon oxide films (hereinafter also referred to as "polishing liquid composition of the present disclosure"). According to the polishing composition of the present disclosure, it is possible to improve the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions on the substrate surface.

Although the details of the mechanism by which the effects of the present disclosure are manifested are not clear, it is speculated as follows.
Ceria particles are generally used for polishing a silicon oxide film. Normally, cerium in ceria particles is tetravalent, and in rare cases oxygen (O) is dropped to become trivalent. It is believed that the trivalent cerium in the ceria particles weakens the Si—O bond of the silicon oxide film, weakens the silicon oxide film, and promotes polishing.
In the present disclosure, by using ceria particles (component A) having a predetermined oxygen storage capacity and a heteroaromatic compound (component B) in combination, adsorption of the ceria particles to the silicon oxide film is promoted, and In order to improve the contact probability of the ceria particles, it is thought that the speed of polishing the convex portions of the silicon oxide film on the substrate surface (protrusion elimination speed) can be improved. Furthermore, in addition to the above effects, the reducing heteroaromatic compound is believed to promote the desorption of oxygen from the ceria particles, promote the weakening of the silicon oxide film, and further promote the polishing rate.
However, the present disclosure need not be construed as being limited to these mechanisms.

[Film to be Polished]
In one or more embodiments, the polishing liquid composition of the present disclosure is a polishing liquid composition (polishing liquid composition for silicon oxide film) used for polishing a silicon oxide film, and requires polishing of a silicon oxide film. It can be used in the process of For example, in one or more embodiments, the polishing composition of the present disclosure is used to polish a silicon oxide film in the step of forming an element isolation structure of a semiconductor substrate, It can be used for polishing a film, polishing a silicon oxide film in the process of forming an embedded metal wiring, or polishing a silicon oxide film in the process of forming an embedded capacitor. In addition, in one or more embodiments, the polishing composition of the present disclosure can be used for manufacturing a three-dimensional semiconductor device such as a three-dimensional NAND flash memory.
In particular, the polishing composition of the present disclosure can be suitably used for polishing a substrate having silicon oxide film protrusions. In one or a plurality of embodiments, the silicon oxide film protrusions are protrusions of the silicon oxide film on the substrate surface, and include, for example, protrusions having a width of 10 μm to 500 μm and a height of 4 μm to 10 μm. In one or more embodiments, the silicon oxide film protrusion can be formed by an extra-etching process before CMP of the interlayer insulating film of the three-dimensional NAND flash memory. In one or more embodiments, the silicon oxide film protrusions are silicon oxide film protrusions on the substrate surface after extra etching. In one or more embodiments, the substrate having silicon oxide film protrusions is a substrate after extra etching before CMP of the interlayer insulating film of the three-dimensional NAND flash memory. In one or more embodiments, the polishing composition of the present disclosure is for polishing a substrate after extra etching.

[Cerium oxide (ceria) particles (component A)]
The polishing composition of the present disclosure contains ceria particles (hereinafter also simply referred to as “component A”) as abrasive grains. Component A may be of one type or a combination of two or more types.

Component A preferably has a high oxygen storage capacity from the viewpoint of improving the polishing rate (protrusion elimination rate) of the silicon oxide film protrusions. In the present disclosure, the oxygen storage capacity refers to the function of absorbing and releasing oxygen along with the oxidation-reduction of cerium ions, and it can be determined that the larger the value of the oxygen storage capacity, the better the oxygen storage capacity and the higher the oxidation-reduction characteristics. . The oxygen storage amount of component A is 50 μmol/g or more, preferably 75 μmol/g or more, more preferably 100 μmol/g or more, from the viewpoint of improving the polishing speed (protrusion elimination speed) of the silicon oxide film convex portions. 125 μmol/g or more is more preferable, and 150 μmol/g or more is even more preferable. In addition, the oxygen storage amount of component A is preferably 500 μmol/g or less, more preferably 300 μmol/g or less, and even more preferably 250 μmol/g or less, from the viewpoint of long-term stability of the ceria particles. In the present disclosure, the oxygen storage amount can be measured using a thermogravimetric differential thermal analyzer, specifically by the method described in the Examples. The oxygen storage capacity of component A can be adjusted by controlling the crystallinity of the ceria particles.

The manufacturing method, shape, and surface state of Component A are not particularly limited. Examples of component A include colloidal ceria, amorphous ceria, and ceria-coated silica.
Colloidal ceria 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 amorphous ceria include pulverized ceria. An embodiment of the pulverized ceria includes, for example, calcined and pulverized ceria obtained by calcining and pulverizing a cerium compound such as cerium carbonate or cerium nitrate. Other embodiments of ground ceria include, for example, single crystal ground ceria obtained by wet grinding ceria particles in the presence of an inorganic acid or an organic acid. Examples of inorganic acids used for wet pulverization include nitric acid, and examples of organic acids include organic acids having a carboxyl group, specifically acetic acid, propionic acid, picolinic acid, glutamic acid, and asparagine. At least one selected from acids, aminobenzoic acid and p-hydroxybenzoic acid can be used. Examples of wet pulverization methods include wet pulverization using a planetary bead mill or the like.
As ceria-coated silica, for example, at least a part of the silica particle surface is granular by the method described in Examples 1 to 14 of JP-A-2015-63451 or Examples 1-4 of JP-A-2013-119131. Composite particles having a structure coated with ceria can be mentioned, and the composite particles can be obtained, for example, by depositing ceria on silica particles.

Examples of the shape of component A include substantially spherical, polyhedral, and raspberry-like.

The average primary particle size of component A is preferably 5 nm or more, more preferably 10 nm or more, from the viewpoint of improving the polishing speed (protrusion elimination speed) of the silicon oxide film convex portions. It is preferably 300 nm or less, more preferably 200 nm or less, still more preferably 100 nm or less, and even more preferably 45 nm or less. From the same viewpoint, the average primary particle size of component A is preferably 5 nm or more and 300 nm or less, more preferably 10 nm or more and 200 nm or less, still more preferably 10 nm or more and 100 nm or less, and even more preferably 10 nm or more and 45 nm or less. In the present disclosure, the average primary particle size of component 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.

The content of Component A in the polishing liquid composition of the present disclosure is such that, when the total content of Component A, Component B, and water is 100% by mass, the rate of polishing the convex portions of the silicon oxide film (the rate of eliminating convex portions) is improved. From the viewpoint, it is preferably 0.001% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and further preferably 0.3% by mass or more. 0.4% by mass or more is more preferable, and from the viewpoint of cost reduction, 5% by mass or less is preferable, 2.5% by mass or less is more preferable, and 1% by mass or less is even more preferable. From the same point of view, the content of component A in the polishing composition of the present disclosure is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 2.5% by mass or less, 0.1% by mass or more and 1% by mass or less is more preferable. When component A is a combination of two or more types of ceria particles, the content of component A refers to their total content.

[Heteroaromatic Compound (Component B)]
In one or a plurality of embodiments, the heteroaromatic compound contained in the polishing composition of the present disclosure (hereinafter also simply referred to as “component B”) has a polishing rate of silicon oxide film protrusions (protrusion elimination rate) From the viewpoint of improvement, nitrogen-containing heteroaromatic compounds in which at least one hydrogen atom is substituted with a hydroxyl group, a thiol group, or a carboxyl group include nitrogen-containing heteroaromatic compounds in which at least one hydrogen atom is substituted with a hydroxyl group or a thiol group. Heteroaromatic compounds are preferred, and nitrogen-containing heteroaromatic compounds in which at least one hydrogen atom is substituted with a hydroxyl group are more preferred. Component B may be one type or a combination of two or more types.

Component B is an N-oxide compound containing a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom is substituted with a hydroxyl group, from the viewpoint of improving the polishing rate (protrusion elimination rate) of the silicon oxide film protrusions, or A salt thereof (hereinafter also referred to as "component B1"), an N-oxide compound containing a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom is substituted with a thiol group, or a salt thereof (hereinafter also referred to as "component B2" ), and a compound containing a nitrogen-containing heteroaromatic ring skeleton having at least one carboxyl group or a salt thereof (hereinafter also referred to as “component B3”), wherein at least one hydrogen atom is a hydroxyl group N-oxide compound or salt thereof (component B1) comprising a nitrogen-containing heteroaromatic ring skeleton substituted with and N- At least one selected from oxide compounds or salts thereof (component B2) is more preferable, and an N-oxide compound or a salt thereof (component B1 ) is more preferred.

In the present disclosure, an N-oxide compound refers, in one or more embodiments, to a compound having an N-oxide group (N→O group). The N-oxide compound can have one or more N→O groups, and one N→O group is preferred from the standpoint of availability.

<N-oxide compound (component B1)>
Component B contained in the polishing composition of the present disclosure, in one or more embodiments, comprises a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom of the nitrogen-containing heteroaromatic ring is substituted with a hydroxyl group. - an oxide compound or a salt thereof (component B1). Examples of the above salts include alkali metal salts, alkaline earth metal salts, organic amine salts, ammonium salts and the like. Component B1 may be used singly or in combination of two or more.

In the present disclosure, "a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom is substituted with a hydroxyl group" refers to a structure in which at least one hydrogen atom of the nitrogen-containing heteroaromatic ring is substituted with a hydroxyl group.
In the present disclosure, at least one nitrogen atom contained in the nitrogen-containing heteroaromatic skeleton of component B1 forms an N-oxide. In one or more embodiments, the nitrogen-containing heteroaromatic ring contained in component B1 includes a monocyclic or bicyclic condensed ring. In one or a plurality of embodiments, the number of nitrogen atoms in the nitrogen-containing heteroaromatic ring contained in component B1 is 1 to 3, from the viewpoint of improving the polishing rate (protrusion elimination rate) of the silicon oxide film protrusions. Therefore, 1 or 2 is preferred, and 1 is more preferred.
In one or more embodiments, the nitrogen-containing heteroaromatic ring skeleton contained in component B1 includes at least one selected from a pyridine N-oxide skeleton, a quinoline N-oxide skeleton, and the like. In the present disclosure, the pyridine N-oxide skeleton indicates a structure in which the nitrogen atoms contained in the pyridine ring form an N-oxide. A quinoline N-oxide skeleton indicates a structure in which a nitrogen atom contained in a quinoline ring forms an N-oxide.

As component B1, in one or more embodiments, an N-oxide compound having a pyridine ring in which at least one hydrogen atom of the pyridine ring is substituted with a hydroxy group, a quinoline ring in which at least one hydrogen atom of the quinoline ring is substituted with a hydroxy group at least one selected from N-oxide compounds having a quinoline ring and salts thereof. Among these, N-oxide having a pyridine ring in which at least one hydrogen atom of the pyridine ring is substituted with a hydroxy group, as the component B1, from the viewpoint of improving the polishing rate (protrusion elimination rate) of the silicon oxide film protrusions. A compound or a salt thereof is preferred.

Component B1 includes, for example, at least one selected from 2-hydroxypyridine N-oxide and salts thereof.

<N-oxide compound (component B2)>
Component B contained in the polishing composition of the present disclosure, in one or more embodiments, contains a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom of the nitrogen-containing heteroaromatic ring skeleton is substituted with a thiol group. N-oxide compounds or salts thereof (component B2). Examples of the above salts include alkali metal salts, alkaline earth metal salts, organic amine salts, ammonium salts and the like. Component B2 may be used singly or in combination of two or more.

In the present disclosure, "a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom is substituted with a thiol group" refers to a structure in which at least one hydrogen atom of the nitrogen-containing heteroaromatic ring is substituted with a thiol group.
In the present disclosure, at least one nitrogen atom contained in the nitrogen-containing heteroaromatic skeleton of component B2 forms an N-oxide. Nitrogen-containing heteroaromatic rings contained in component B2 include, in one or more embodiments, monocyclic or bicyclic condensed rings. In one or a plurality of embodiments, the number of nitrogen atoms in the nitrogen-containing heteroaromatic ring contained in component B2 is 1 to 3, from the viewpoint of improving the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions. Therefore, 1 or 2 is preferred, and 1 is more preferred.
In one or more embodiments, the nitrogen-containing heteroaromatic ring skeleton contained in component B2 includes at least one selected from a pyridine N-oxide skeleton, a quinoline N-oxide skeleton, and the like. In the present disclosure, the pyridine N-oxide skeleton indicates a structure in which the nitrogen atoms contained in the pyridine ring form an N-oxide. A quinoline N-oxide skeleton indicates a structure in which a nitrogen atom contained in a quinoline ring forms an N-oxide.

As component B2, in one or more embodiments, an N-oxide compound having a pyridine ring in which at least one hydrogen atom on the pyridine ring is substituted with a thiol group (—SH), at least one hydrogen atom on the quinoline ring is At least one selected from N-oxide compounds having a quinoline ring substituted with a thiol group (-SH) and salts thereof. Among these, a pyridine ring in which at least one hydrogen atom of the pyridine ring is substituted with a thiol group (—SH) is used as the component B2 from the viewpoint of improving the polishing rate (protrusion elimination rate) of the silicon oxide film protrusions. or salts thereof are preferred.

Component B2 includes, for example, 2-mercaptopyridine N-oxide or a salt thereof.

<Nitrogen-Containing Heteroaromatic Ring Compound (Component B3)>
Component B contained in the polishing composition of the present disclosure is, in one or more embodiments, a compound or a salt thereof containing a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom is substituted with a carboxyl group (component B3) is. Examples of the above salts include alkali metal salts, alkaline earth metal salts, organic amine salts such as ethanolamine salts, and ammonium salts. Component B3 may be used singly or in combination of two or more.

Nitrogen-containing heteroaromatic rings contained in component B3 include, in one or more embodiments, monocyclic or bicyclic condensed rings. In one or more embodiments, the number of nitrogen atoms in the nitrogen-containing heteroaromatic ring contained in component B3 is 1 to 3, from the viewpoint of improving the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions. Therefore, 1 or 2 is preferred, and 1 is more preferred.
In one or more embodiments, the nitrogen-containing heteroaromatic ring skeleton contained in component B3 includes a pyridine skeleton.

Component B3 is preferably a compound having at least one carboxyl group on the pyridine ring or a salt thereof, such as picolinic acid, picolinic acid N-oxide, nicotinic acid, and isonicotinic acid.

Component B has a reduction potential when a 10 ppm aqueous solution of Component B is measured by cyclic voltammetry (Ag/AgCl electrode standard, 25° C.) from the viewpoint of improving the polishing speed (protrusion elimination speed) of silicon oxide film convex portions. A compound having a voltage of 0.45 V or more is preferable. The reduction potential is preferably 0.45 V or higher, more preferably 0.50 V or higher, still more preferably 0.55 V or higher, and 0.60 V from the viewpoint of improving the polishing speed (protrusion elimination speed) of the silicon oxide film convex portion. more preferably 0.65 V or more, more preferably 0.70 V or more, still more preferably 0.75 V or more, still more preferably 0.80 V or more, still more preferably 0.85 V or more, and 0.95 V The following is preferable, and 0.90 V or less is more preferable. The reduction potential can be measured by the method described in Examples.

In one or more embodiments, the content of Component B in the polishing composition of the present disclosure is From the viewpoint of improving the polishing speed (protrusion elimination speed), it is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and from the viewpoint of ensuring the dispersibility of the ceria particles, it is preferably 1% by mass or less. , is more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less. From the same viewpoint, the content of component B in the polishing composition of the present disclosure is preferably 0.001% by mass or more and 1% by mass or less, more preferably 0.005% by mass or more and 0.5% by mass or less, 0.005% by mass or more and 0.1% by mass or less is more preferable, and 0.005% by mass or more and 0.05% by mass or less is even more preferable. When component B is a combination of two or more, the content of component B refers to the total content thereof.

In one or more embodiments, the mass ratio A/B (content of component A/content of component B) between component A and component B in the polishing composition of the present disclosure is From the viewpoint of improving the polishing speed (protrusion elimination speed), it is more preferably 1 or more, more preferably 5 or more, still more preferably 10 or more, still more preferably 20 or more, still more preferably 26 or more, further preferably 32 or more, and , is preferably 100 or less, more preferably 50 or less, and even more preferably 40 or less. From the same viewpoint, the mass ratio A/B in the polishing composition of the present disclosure is preferably 1 or more and 100 or less, more preferably 5 or more and 50 or less, and even more preferably 10 or more and 40 or less.

[Aqueous medium]
The aqueous medium contained in the polishing composition of the present disclosure includes water such as distilled water, ion-exchanged water, pure water and ultrapure water, or a mixed solvent of water and a solvent. Examples of the solvent include water-miscible solvents (for example, alcohol such as ethanol). When the aqueous medium is a mixed solvent of water and a solvent, the ratio of water to the entire mixed medium may not be particularly limited as long as the effects of the present disclosure are not hindered. , is preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably substantially 100% by mass. From the viewpoint of surface cleanliness of the substrate to be polished, the aqueous medium is preferably water, more preferably ion-exchanged water or ultrapure water, and still more preferably ultrapure water. The content of the aqueous medium in the polishing composition of the present disclosure can be the balance after removing component A, component B, and optional components described later that are blended as necessary.

[Compound represented by formula (I) (component C)]
The polishing composition of the present disclosure is a compound represented by the following formula (I) (hereinafter also simply referred to as “component C”) from the viewpoint of further improving the polishing rate (protrusion elimination rate) of silicon oxide film protrusions. ) can be further included. Component C may be one type or a combination of two or more types.

In formula (I), R ¹ and R ² are the same or different and represent a hydroxyl group or a salt thereof, and R ³ is H, —NH ₂ , —NHCH ₃ , —NC ₂ H ₆ , —N ⁺ ( CH ₃ ) ₃ represents an alkyl group, a phenyl group, a cytidine group, a guanidino group or an alkylguanidino group, X represents a bond or an alkylene group having from 1 to 12 carbon atoms, and n represents 0 or 1.

In formula (I), each of R ¹ and R ² is preferably a hydroxyl group from the viewpoint of solubility in the polishing composition.
R ³ is H, —NH ₂ , —N ⁺ (CH ₃ ) ₃ , alkyl group, phenyl group, cytidine group, or An alkylguanidino group is preferred, an alkylguanidino group or a phenyl group is more preferred, and an alkylguanidino group is even more preferred. From the viewpoint of solubility in the polishing composition, the alkyl group is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 2 to 6 carbon atoms, and an alkyl group having 4 carbon atoms (butyl group) is more preferred. The alkylguanidino group is more preferably an alkylguanidino group having 2 or more and 12 or less carbon atoms, and more preferably an alkylguanidino group having 2 or more and 4 or less carbon atoms, from the viewpoint of further improving the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions. is more preferred, a methylguanidino group is more preferred, and a 1-methylguanidino group is even more preferred.
X is preferably an alkylene group having 1 or more and 12 or less carbon atoms, more preferably an alkylene group having 1 or more and 10 or less carbon atoms, from the viewpoint of further improving the polishing rate (protrusion elimination rate) of the silicon oxide film protrusions. An alkylene group having 1 to 8 carbon atoms is more preferable, an alkylene group having 1 to 6 carbon atoms is more preferable, an alkylene group having 1 to 4 carbon atoms is preferable, and an alkylene group having 2 or 3 carbon atoms is more preferable. An alkylene group of number 2 (ethylene group) is preferred.
n is preferably 1 from the viewpoint of further improving the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions.

Component C includes, for example, creatinol phosphate, O-phosphorylethanolamine, phosphocholine chloride sodium hydrate, butylphosphonic acid, phenylphosphonic acid, cytidine 5-phosphate and the like. Among these, component C is at least one selected from creatinol phosphate, phenylphosphonic acid and salts thereof, from the viewpoint of further improving the polishing rate (protrusion elimination rate) of silicon oxide film protrusions (protrusion elimination rate) and availability. Seeds are preferred.

The content of component C in the polishing composition of the present disclosure is preferably 0.001% by mass or more, more preferably 0.0015, from the viewpoint of improving the polishing rate (protrusion elimination rate) of the silicon oxide film protrusions. It is at least 0.002% by mass, more preferably at least 0.002% by mass. From the viewpoint of ensuring the dispersibility of the ceria particles, it is preferably 1% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less. From the same viewpoint, the content of component C in the polishing composition of the present disclosure is preferably 0.001% by mass or more and 1% by mass or less, more preferably 0.0015% by mass or more and 0.1% by mass or less, 0.002% by mass or more and 0.05% by mass or less is more preferable. When component C is a combination of two or more, the content of component C refers to the total content thereof.

[Other ingredients]
The polishing composition of the present disclosure may further contain other components as long as the effects of the present disclosure are not impaired. Other components include, for example, pH adjusters, surfactants, thickeners, dispersants, rust inhibitors, preservatives, basic substances, polishing speed improvers, counterions and the like. When the polishing composition of the present disclosure further contains other components, the content of the other components in the polishing composition of the present disclosure is preferably 0.001% by mass or more from the viewpoint of improving the polishing rate. 0.0025% by mass or more is more preferable, 0.01% by mass or more is still more preferable, and 1% by mass or less is preferable, 0.5% by mass or less is more preferable, and 0.1% by mass or less is even more preferable.

[Polishing liquid composition]
The polishing composition of the present disclosure is manufactured by a manufacturing method including, for example, a step of blending component A, component B, an aqueous medium, and optionally the above optional components (component C and other components) by a known method. can. For example, the polishing composition of the present disclosure can be made by blending at least component A, component B and an aqueous medium. When component A is a combination of multiple types of ceria particles, component A can be obtained by blending multiple types of ceria particles. When component B is a combination of multiple types of heteroaromatic compounds, component B can be obtained by blending multiple types of heteroaromatic compounds. In the present disclosure, "blending" includes mixing component A, component B, an aqueous medium, and optionally the above optional components (component C and other components) simultaneously or in order. The order of mixing is not particularly limited. The blending can be performed using 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 composition of the present disclosure can be the same as the content of each component in the polishing composition of the present disclosure described above.

Embodiments of the polishing composition of the present disclosure may be a so-called one-component type in which all components are premixed and supplied to the market, or a so-called two-component type in which they are mixed at the time of use. There may be. The two-part polishing composition is composed of, for example, a first liquid containing a component A and a second liquid containing a component B, and the first liquid and the second liquid are mixed at the time of use. mentioned. 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 first liquid and the second liquid can each contain the optional components described above as necessary.

The pH of the polishing composition of the present disclosure is preferably 3.5 or higher, more preferably 4 or higher, and even more preferably 4.5 or higher, from the viewpoint of improving the polishing speed (protrusion elimination speed) of the silicon oxide film convex portions. , and preferably 9 or less, more preferably 8.5 or less, still more preferably 8 or less, still more preferably less than 8, still more preferably 7 or less, and even more preferably 6 or less. From the same viewpoint, the pH of the polishing composition of the present disclosure is preferably 3.5 to 9, more preferably 4 to 8.5, even more preferably 4.5 to 8, and 4.5 to 8. Less than is more preferable, 4.5 or more and 7 or less is still more preferable, and 4.5 or more and 6 or less is still more preferable. In the present disclosure, the pH of the polishing composition is a value at 25° C. and can be measured using a pH meter, specifically by the method described in Examples.

In the present disclosure, "the content of each component in the polishing composition" refers to the content of each component at the time of polishing, that is, when the polishing composition is started to be used for polishing. The polishing composition of the present disclosure may be stored and supplied in a concentrated state to the extent that its stability is not impaired. In this case, it is preferable in that manufacturing and transportation costs can be reduced. This concentrated solution can be diluted with water as necessary and used in the polishing process. The dilution ratio is preferably 5 to 100 times.

[Polishing liquid kit]
In another aspect, the present disclosure relates to a kit for producing the polishing composition of the present disclosure (hereinafter also referred to as "polishing liquid kit of the present disclosure").
As the polishing liquid kit of the present disclosure, for example, a polishing liquid kit (two-liquid type polishing liquid composition). The abrasive grain dispersion and the additive aqueous solution are mixed at the time of use and diluted with an aqueous medium as necessary. The aqueous medium contained in the abrasive grain dispersion may be the total amount or a part of the aqueous medium used for preparing the polishing composition. The aqueous additive solution may contain a part of the aqueous medium used for preparing the polishing composition. The abrasive grain dispersion and the additive aqueous solution may each contain optional components (component C and other components) as required.
According to the polishing liquid kit of the present disclosure, it is possible to obtain a polishing liquid composition capable of improving the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions.

[Polishing method]
In one aspect, the present disclosure includes a step of polishing a film-to-be-polished using the polishing composition of the present disclosure, wherein the film-to-be-polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate. The present invention relates to a method (hereinafter also referred to as a polishing method of the present disclosure). Examples of the film to be polished include the film to be polished in the above-described polishing composition of the present disclosure. For example, in one or more embodiments, the film to be polished in the polishing method of the present disclosure is a silicon oxide film protrusion on the substrate surface after extra etching. The polishing method of the present disclosure, in one or more embodiments, includes the step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure. In one or more embodiments, the substrate to be polished is a substrate after extra etching, and in one or more embodiments, it is a substrate having silicon oxide film protrusions. By using the polishing method of the present disclosure, it is possible to improve the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions, so that it is possible to improve the productivity of semiconductor substrates with improved quality. sell. The polishing method and conditions in the polishing method of the present disclosure can be the same as those of the semiconductor substrate manufacturing method of the present disclosure, which will be described later.

[Method for manufacturing semiconductor substrate]
In one aspect of the present disclosure, a method for manufacturing a semiconductor substrate (hereinafter referred to as "method for manufacturing a semiconductor substrate of the present disclosure") includes a step of polishing a film to be polished using a polishing composition of the present disclosure (polishing step). Also called). Examples of the film to be polished include the film to be polished in the above-described polishing composition of the present disclosure. For example, in one or a plurality of embodiments, the film to be polished in the method for manufacturing a semiconductor substrate of the present disclosure is a silicon oxide film protrusion on the substrate surface after extra etching. In one or more embodiments, the method for manufacturing a semiconductor substrate of the present disclosure includes the step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure. In one or more embodiments, the substrate to be polished is a substrate after extra etching, and in one or more embodiments, it is a substrate having silicon oxide film protrusions. According to the method for manufacturing a semiconductor substrate of the present disclosure, it is possible to improve the polishing speed (protrusion elimination speed) of the silicon oxide film protrusions, so that it is possible to efficiently manufacture semiconductor substrates with improved quality. sell.

As a specific example of the method for manufacturing a semiconductor substrate of the present disclosure, first, a silicon dioxide film is alternately laminated on a silicon substrate, and then a silicon nitride (Si ₃ N ₄ ) film is laminated on the silicon dioxide layer. After that, a polysilicon channel is formed, a laminated film is trimmed, a charge trap layer is formed, a tungsten (W) gate is formed, and an array is formed. Thereafter, a silicon dioxide layer is deposited on the array by CVD (chemical vapor deposition) or the like. The silicon oxide film thus formed has a large step between the array portion and the peripheral portion. Then, by CMP, the silicon oxide film in the array portion is polished until it becomes the same height as the peripheral portion. As shown in FIG. 2, a method has been proposed in which an extra-etching process is performed before CMP to make the protrusions finer, improve the CMP efficiency, and shorten the polishing time.
In one or more embodiments, the polishing composition of the present disclosure can be suitably used for polishing a substrate having silicon oxide film protrusions after extra etching. In one or a plurality of embodiments, the silicon oxide film protrusions are protrusions of the silicon oxide film on the substrate surface, and include, for example, protrusions having a width of 10 μm to 500 μm and a height of 4 μm to 10 μm.

In CMP polishing, the substrate to be polished and the polishing pad are relatively moved while the polishing liquid composition of the present disclosure is supplied to the contact portion of the substrate in contact with the polishing pad. to flatten the irregularities on the surface of the substrate to be polished.

In the polishing step, the number of revolutions of the polishing pad is, for example, 30 to 200 rpm/min, the number of revolutions of the substrate to be polished is, for example, 30 to 200 rpm/min, and the polishing load set to the polishing apparatus equipped with the polishing pad is , for example, 20 to 500 g weight/cm ² , and the supply rate of the polishing composition can be set, for example, to 10 to 500 mL/min or less. When the polishing liquid composition is a two-component polishing liquid composition, the polishing rate of the film-to-be-polished can be adjusted by adjusting the supply speed (or supply amount) of each of the first liquid and the second liquid.

In the polishing step, the polishing rate of the film to be polished (silicon oxide film) is preferably 50 nm/min or more, more preferably 80 nm/min or more, and even more preferably 90 nm/min or more, from the viewpoint of improving productivity.

EXAMPLES The present disclosure will be described below with reference to Examples, but the present disclosure is not limited thereto.

1. Measurement method of each parameter (1) pH of polishing composition
The pH value of the polishing composition at 25° C. is a value measured using a pH meter (“HM-30G” manufactured by Toa Denpa Kogyo Co., Ltd.). It is the number after minutes.

( ² ) Average Primary Particle Size of Ceria Particles (Component A) was used, and the true density of the ceria particles was calculated as 7.2 g/cm ³ .

(3) BET Specific Surface Area of Ceria Particles (Component A) The specific surface area was obtained by drying a ceria dispersion liquid with hot air at 120° C. for 3 hours and then pulverizing it finely with an agate mortar. After drying for 15 minutes in an atmosphere of 120 ° C. immediately before the measurement, it was measured by the 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). .

(4) Oxygen Storage Amount of Ceria Particles The oxygen storage amount of ceria particles was measured by the following method using a thermogravimetric differential thermal analyzer (Thermo plus TG8110, manufactured by Rigaku).
The ceria dispersion was dried with hot air at 600° C. for 3 hours and then finely pulverized in an agate mortar. After that, the ceria particles were placed in a Pt pan and set in the apparatus. A gas of nitrogen:hydrogen=1:1 was filled in the apparatus, and the temperature was raised from room temperature to 800° C. to reduce the ceria particles. While maintaining the temperature at 800° C., the inside of the system was replaced with nitrogen and maintained for 30 minutes. Next, the ceria particles were oxidized with a gas of oxygen:nitrogen=1:9. At this time, the amount of oxygen absorbed by the ceria particles was used to calculate the oxygen storage amount (μmol/g).

(5) Reduction potential 1) An aqueous sodium sulfate solution used as a supporting electrolyte is prepared with ultrapure water so as to have a concentration of 0.1 mol/L, and nitrogen substitution is performed for 3 hours or more.
2) 9.9 mL of sodium sulfate aqueous solution is weighed into a glass vial (20 mL).
3) The surface of the glassy carbon (glassy carbon) working electrode is pressed vertically using a 1 μm polishing diamond and a diamond polishing pad (both manufactured by BAS) to draw a figure 8. Polish enough to Subsequently, using 0.05 μm alumina and an alumina polishing pad (both manufactured by BAS), the electrode surface is sufficiently polished in a figure-of-eight pattern until it becomes a mirror surface. Thereafter, the electrode surface is washed with ultrapure water and dried.
4) Connect a glassy carbon electrode, a silver/silver chloride reference electrode, and a platinum counter electrode to an ALS electrochemical analyzer (model 611D) and immerse in an aqueous sodium sulfate solution to assemble a 3-electrode electrochemical cell.
5) Set the cyclic voltammetry variables to 1 V high, 1 V low, 0.1 V/s scan rate, 5 w sweep segments, and display the potential-current data points on the monitor.
6) After a Teflon (registered trademark) tube is passed through the glass vial and the glass vial is sufficiently purged with nitrogen, the measurement is performed only with the supporting electrolyte. At this time, if the nitrogen substitution is insufficient, a peak derived from dissolved oxygen is detected.
7) A measurement sample (additive: 1000 ppm) was prepared with ultrapure water, and after sufficient nitrogen substitution, 0.1 mL of the measurement sample was added to 9.9 mL of an aqueous sodium sulfate solution in a glass vial, and added. A 10 ppm aqueous solution of the agent was obtained.
8) Measure the Open Circuit Potential and set it to the initial potential of the cyclic voltammetry variable and take the measurement. At this time, it is confirmed that no peak derived from dissolved oxygen is detected, and the oxidation-reduction potential is confirmed from the cyclic voltammogram derived from the measurement sample.

2. Preparation of polishing composition (Examples 1-12 and Comparative Examples 1-2)
(Examples 1-9, 12 and Comparative Examples 1-2)
Ceria particles (component A shown in Tables 1 and 3), heteroaromatic compounds (component B shown in Tables 2 and 3) and water were mixed to polish Examples 1 to 9, 12 and Comparative Examples 1 and 2. A liquid composition was obtained. The content of each component in each polishing composition is as shown in Table 3. The content of water is the remainder after component A and component B are removed.
(Examples 10-11)
Ceria particles (Component A shown in Tables 1 and 3), heteroaromatic compounds (Component B shown in Tables 2 and 3), compounds (Component C shown in Table 3), and water were mixed to form Examples 10 and 11. was obtained. The content of each component in each polishing composition is as shown in Table 3. The content of water is the remainder after component A, component B and component C are removed.
The pH of the polishing compositions of Examples 1-12 and Comparative Examples 1-2 was 5. pH adjustments were performed using ammonia or nitric acid.

Details of Component A, Component B and (Component C) used in the preparation of the polishing compositions of Examples 1 to 12 and Comparative Examples 1 and 2 are shown in Tables 1 and 2 and below.
(Component B)
B1: 2-hydroxypyridine N-oxide (manufactured by Tokyo Chemical Industry Co., Ltd.)
B2: 2-mercaptopyridine N-oxide (manufactured by Tokyo Chemical Industry Co., Ltd.)
B3: picolinic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
(Component C)
C1: creatinol phosphate (manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (I), R ¹ : OH, R ² : OH, R ³ : 1-methylguanidino group, X: ethylene group, n: 1. ]
C2: Phenylphosphonic acid (manufactured by Tokyo Kasei Kogyo Co., Ltd.) [In formula (I), R ¹ : OH, R ² : OH, R ³ : phenyl group, X: bond, n: 0. ]

3. Evaluation of Polishing Liquid Compositions (Examples 1 to 12 and Comparative Examples 1 and 2) [Evaluation Sample]
A wafer (200 mm in diameter) shown in FIG. 1 was used as an evaluation sample. In this evaluation sample, after forming a silicon oxide film with a thickness of 6 μm on a silicon substrate, dry etching is performed to form a grid-like uneven portion as shown in FIG. The recess has a size of 20 mm long×20 mm wide×4 μm deep. The silicon oxide film is made of P-TEOS. This evaluation sample is a model substrate of a substrate having silicon oxide film protrusions after extra etching.

[Polishing conditions]
Polishing device: Single-sided polishing machine [FREX-200, manufactured by Ebara Corporation]
Polishing pad: Hard urethane pad "IC-1000/Suba400" [manufactured by Nitta Haas]
Surface plate rotation speed: 100 rpm
Head rotation speed: 107 rpm
Polishing load: 280hPa
Amount of polishing liquid supplied: 200 mL/min Polishing time: 1 minute

[Protrusion elimination speed]
Using each of the polishing liquid compositions of Examples 1 to 12 and Comparative Examples 1 and 2, samples for evaluation were polished under the above polishing conditions.
Before and after polishing, the film thickness of the silicon oxide film on the convex portion with a wiring width of 500 μm was measured using ASET-F5X (manufactured by KLA). The convex elimination speed was determined by the following formula, and Table 3 shows the results when the polishing speed of Comparative Example 1 was set to 100.
Protrusion elimination rate = [silicon oxide film thickness on protruding part before polishing (Å) - silicon oxide film thickness on protruding part after polishing (Å)]/polishing time (min)

As shown in Table 3, Examples 1 to 12 in which cerium oxide particles having an oxygen storage amount of 50 μmol/g or more and a heteroaromatic compound were used in combination used cerium oxide particles having an oxygen storage amount of less than 50 μmol/g. Compared to Comparative Example 1, which was used, the convex elimination speed was improved. In Comparative Example 2, in which cerium oxide particles having an oxygen storage amount of 50 μmol/g or more were used, but no heteroaromatic compound was used, polishing did not progress.

The polishing composition of the present disclosure is useful in methods of manufacturing semiconductor substrates for high density or high integration.

Claims (12)

Containing cerium oxide particles (component A), a heteroaromatic compound (component B), and an aqueous medium,
A polishing liquid composition for silicon oxide films, wherein component A has an oxygen storage amount of 50 μmol/g or more. 2. The polishing composition according to claim 1, wherein component A has an oxygen storage capacity of 100 [mu]mol/g or more. 3. The polishing according to claim 1, wherein component B is a compound having a reduction potential of 0.45 V or more when a 10 ppm aqueous solution of component B is measured by cyclic voltammetry (Ag/AgCl electrode standard, 25° C.). liquid composition. 4. The polishing composition according to any one of claims 1 to 3, wherein component B is a nitrogen-containing heteroaromatic compound in which at least one hydrogen atom is substituted with a hydroxyl group. Component B is an N-oxide compound having a pyridine ring in which at least one hydrogen atom on the pyridine ring is substituted with a hydroxyl group, or an N-oxide having a quinoline ring in which at least one hydrogen atom on the quinoline ring is substituted with a hydroxyl group. The polishing composition according to any one of claims 1 to 4, which is at least one selected from compounds and salts thereof. 6. The polishing composition according to any one of claims 1 to 5, wherein component B is at least one selected from 2-hydroxypyridine N-oxide and salts thereof. 7. The polishing composition according to any one of claims 1 to 6, further comprising a compound (component C) represented by formula (I) below.

In formula (I), R ¹ and R ² are the same or different and represent a hydroxyl group or a salt thereof, and R ³ is H, —NH ₂ , —NHCH ₃ , —NC ₂ H ₆ , —N ⁺ ( CH ₃ ) ₃ represents an alkyl group, a phenyl group, a cytidine group, a guanidino group or an alkylguanidino group, X represents a bond or an alkylene group having from 1 to 12 carbon atoms, and n represents 0 or 1. 8. The polishing composition according to claim 7, wherein component C is at least one selected from creatinol phosphate, phenylphosphonic acid and salts thereof. 9. The polishing composition according to any one of claims 1 to 8, for polishing a substrate after extra etching. 10. Polishing, comprising the step of polishing a film-to-be-polished using the polishing composition according to any one of claims 1 to 9, wherein the film-to-be-polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate. Method. A method for manufacturing a semiconductor substrate, comprising the step of polishing a film-to-be-polished using the polishing composition according to any one of claims 1 to 9. 12. The method according to claim 10, wherein said film to be polished is a silicon oxide film protrusion on the substrate surface after extra etching.

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