JP7464432B2 - Cleaning composition for semiconductor device substrates - Google Patents

Description

The present disclosure relates to a cleaning composition for use on substrates for semiconductor devices, a method for cleaning substrates using the cleaning composition, and a method for manufacturing substrates for semiconductor devices.

In recent years, semiconductor devices such as semiconductor integrated circuits have become increasingly miniaturized as processing power improves. As miniaturization advances, high precision flatness is required in each layer of the substrate. Furthermore, from the perspective of production efficiency, etc., it is becoming necessary to simultaneously flatten multiple types of surfaces with different hardness and properties, on which wiring etc. are drawn.

Chemical mechanical polishing (CMP) is commonly used as a technique for ensuring the flatness of substrates for semiconductor devices. In CMP, a polishing pad is used to polish and planarize the substrate surface while supplying an abrasive (slurry) containing abrasive grains. Silica slurry is widely used as an abrasive, but cerium oxide (ceria) slurry is also used. Silica slurry is mainly used to polish substrate surfaces having metal parts such as copper and silicon dioxide (SiO ₂ ) parts, and ceria slurry is mainly used to polish substrate surfaces having SiO ₂ parts and silicon nitride (Si ₃ N ₄ ) parts. After CMP using silica slurry or ceria slurry, cleaning is required to remove polishing debris and abrasive-derived foreign matter remaining on the substrate surface. For example, Patent Document 1 proposes a cleaning solution containing an anionic surfactant, water, and a pH adjuster for cleaning substrates after CMP processing.

JP 2013-8751 A

After CMP using cerium oxide slurry, hydrofluoric acid cleaning is usually performed to remove cerium oxide particles, which are abrasive grains, remaining on the substrate surface. This is because hydrofluoric acid easily dissolves cerium oxide particles. On the other hand, in recent years, in the field of semiconductor devices, there is a tendency to narrow the wiring width for the purpose of miniaturization, so it is required to suppress scratches and surface roughness of thermal oxide films such as silicon dioxide (SiO ₂ ) forming the base. Furthermore, hydrofluoric acid has the property of dissolving not only cerium oxide particles but also thermal oxide films such as silicon dioxide (SiO ₂ ), and since hydrofluoric acid cleaning has too strong solubility in thermal oxide films, problems such as enlargement of scratches on thermal oxide films and deterioration of surface roughness arise, which affect the process after cleaning and lead to a decrease in the yield and quality of semiconductor devices. Therefore, instead of hydrofluoric acid, a cleaning agent that has excellent cleaning properties for cerium oxide particles remaining on the substrate surface without reducing flatness is required. However, the cleaning agent composition disclosed in the above patent document does not have sufficient cleaning properties for cerium oxide particles remaining on the substrate surface.

In one or more embodiments, the present disclosure provides a cleaning composition for use on semiconductor device substrates, which has excellent cleaning properties against cerium oxide particles remaining on the substrate surface, a method for cleaning substrates using the cleaning composition, and a method for manufacturing semiconductor device substrates.

In one aspect, the present disclosure relates to a cleaning composition for cleaning a semiconductor device substrate that has been polished with a polishing liquid composition containing cerium oxide particles, the cleaning composition comprising water (component B) and a water-soluble polymer (component A) that includes at least one structural unit a1 selected from a structural unit represented by formula (I) below and a structural unit represented by formula (V) below, and having a pH of 0.5 or more and 5 or less during use.
In formula (I), ^R1 , ^R2 , ^R3 , ^R4 , ^R5 and ^R6 are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group; ^X1 is O or NH; and ^Y1 and ^Y2 are the same or different and each represents an alkylene group having 1 to 4 carbon atoms.
In formula (V), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ and R ²² are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group, X ⁴ is O or NH, and Y ³ and Y ⁴ are the same or different and each represents an alkylene group having 1 to 4 carbon atoms.

In one aspect, the present disclosure relates to a method for cleaning a substrate that has been polished using a polishing composition containing cerium oxide particles, the method comprising pressing a pad against a surface of the substrate and moving the substrate and the pad relative to each other while supplying a cleaning composition of the present disclosure between the substrate and the pad.

In one aspect, the present disclosure relates to a method for producing a substrate for a semiconductor device, comprising a step of cleaning a substrate polished with a polishing composition containing cerium oxide particles using the cleaning method of the present disclosure.

According to one aspect of the present disclosure, a cleaning composition for use with semiconductor device substrates can be provided that has excellent cleaning properties for cerium oxide particles remaining on the substrate surface.

[Cleaning agent composition]
In one aspect, the present disclosure is based on the discovery that the use of a cleaning composition having a pH of 0.5 to 5 containing a specific water-soluble polymer (component A) for cleaning a substrate after CMP using cerium oxide particles (ceria) enables efficient cleaning of the cerium oxide particles remaining on the substrate surface. In another aspect, the present disclosure is based on the discovery that the cleaning composition of the present disclosure is suitable for cleaning a substrate by contacting the substrate with a pad.

That is, in one aspect, the present disclosure relates to a cleaning composition for cleaning a semiconductor device substrate polished with a polishing liquid composition containing cerium oxide particles, the cleaning composition containing a water-soluble polymer (component A) containing at least one structural unit a1 selected from the structural units represented by the above formula (I) and the structural units represented by the above formula (V) and water (component B), and having a pH of 0.5 to 5 during use of the cleaning composition (hereinafter also referred to as the "cleaning composition of the present disclosure"). According to the present disclosure, a cleaning composition for use with a semiconductor device substrate that has excellent cleaning properties for cerium oxide particles remaining on the substrate surface can be provided. Furthermore, by using the cleaning composition of the present disclosure, a high-quality semiconductor device substrate can be obtained.

Although the details of the mechanism of action of the cleaning composition of the present disclosure are partially unknown, it is presumed as follows.
The water-soluble polymer (component A) has both cationic and anionic sites. It is believed that under acidic conditions, the cationic sites of component A are strongly dissociated, and the component A is positively charged. Therefore, when the cleaning composition of the present disclosure containing component A is used to clean a substrate after polishing with cerium oxide particles, under acidic conditions, component A is adsorbed to each of the cerium oxide particles and the thermally oxidized film, and both the cerium oxide particles and the thermally oxidized film are positively charged, making it possible to repel each other. Furthermore, since component A has both cationic and anionic sites, it is believed that it also has a strong interaction with water molecules, forming a hydration layer on the surfaces of both the adsorbed cerium particles and the thermally oxidized film. As a result, it is believed that the cerium oxide particles are easily detached from the thermally oxidized film and are less likely to reattach, thereby improving the cleaning ability. And, when the cleaning composition of the present disclosure is used to clean a substrate by contacting the substrate with a pad, it is believed that the physical force caused by the contact of the pad makes it easier for the cerium oxide particles attached to the substrate to peel off, thereby further improving the cleaning ability.
However, the present disclosure need not be construed as being limited to this mechanism.

In the present disclosure, cleaning of a substrate by contacting the substrate with a pad (hereinafter also referred to as "cleaning using a pad") refers, in one or more embodiments, to cleaning the substrate surface by pressing a pad against the substrate surface and moving the substrate and the pad relative to each other while supplying a cleaning agent composition between the substrate and the pad. Examples of pads include foamed polyurethane pads, nonwoven fabrics, fluororesins, suede pads (buffs), and the like used in general CMP polishing. Cleaning using a suede pad is also called buff cleaning.

[Water-soluble polymer (component A)]
The water-soluble polymer contained in the polishing liquid composition of the present disclosure is a water-soluble polymer (hereinafter, also simply referred to as "component A") containing at least one structural unit a1 selected from the structural unit represented by the following formula (I) and the structural unit represented by the following formula (V) from the viewpoint of improving cleaning properties. In one or more embodiments, component A is preferably at least one selected from a homopolymer consisting of the structural unit a1 described later, a copolymer containing the structural unit a1 described later and the structural unit a2 described later, a copolymer containing the structural unit a1 described later and the structural unit a3 described later, and a copolymer containing the structural unit a1 described later, the structural unit a2 described later, and the structural unit a3 described later. Component A may be one type or a combination of two or more types. In the present disclosure, "water-soluble" means having a solubility of 0.5 g/100 mL or more in water (20° C.), preferably a solubility of 2 g/100 mL or more.

(Structural unit a1)
In one or more embodiments, from the viewpoint of improving cleaning properties, the structural unit a1 is at least one type of structural unit selected from the structural units represented by the following formula (I) and the structural units represented by the following formula (V): The structural unit a1 may be one type, or a combination of two or more types.

In formula (I), ^R1 , ^R2 , ^R3 , ^R4 , ^R5 and ^R6 are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group; ^X1 is O or NH; and ^Y1 and ^Y2 are the same or different and each represents an alkylene group having 1 to 4 carbon atoms.
In formula (I), R ¹ and R ² are each preferably a hydrogen atom from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. R ³ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. R ⁴ , R ⁵ , and R ⁶ are preferably a methyl group from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. X ¹ is preferably O (oxygen atom) from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. Y ¹ and Y ² are preferably an alkylene group having 2 or 3 carbon atoms, more preferably an alkylene group having 2 carbon atoms, from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning.

In formula (V), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ and R ²² are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group, X ⁴ is O or NH, and Y ³ and Y ⁴ are the same or different and each represents an alkylene group having 1 to 4 carbon atoms.
In formula (V), R ¹⁸ and R ¹⁹ are each preferably a hydrogen atom from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. R ²⁰ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. R ²¹ and R ²² are preferably a methyl group from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. X ⁴ is preferably O (oxygen atom) from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. ^{Y 3} is preferably an alkylene group having 2 carbon atoms from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning. Y ⁴ is preferably an alkylene group having 1 carbon atom from the viewpoint of availability of the unsaturated monomer, polymerization of the monomer, and cleaning.

From the viewpoints of availability of unsaturated monomers, polymerizability of monomers, and improved cleaning properties, examples of the constitutional unit represented by formula (I) include constitutional units derived from monomers containing a methacryloyloxyethyl phosphobetaine structure, specifically constitutional units derived from monomers such as 2-methacryloyloxyethyl phosphorylcholine (MPC). Here, the term "monomer containing a methacryloyloxyethyl phosphobetaine structure" refers to a monomer having a methacryloyloxyethyl group and a phosphobetaine group.
From the viewpoints of availability of unsaturated monomers, polymerizability of monomers, and improved cleaning properties, examples of the structural unit represented by formula (V) include structural units derived from monomers containing a methacryloyloxyethyl carbobetaine structure, specifically, structural units derived from monomers such as N-methacryloyloxyethyl-N,N-dimethylammonium-α-N-methylcarboxybetaine (GLBT). Here, the term "monomer containing a methacryloyloxyethyl carboxybetaine structure" refers to a monomer having a methacryloyloxyethyl group and a carbobetaine group.
In the present disclosure, a betaine structure refers to a structure having a positive charge and a negative charge in the same molecule, and the charges are neutralized. The betaine structure has the positive charge and the negative charge preferably at positions that are not adjacent to each other, and preferably at positions separated by one or more atoms.
In addition, in the present disclosure, a phosphobetaine structure is a betaine structure in which a negative charge is dissociated from a phosphate group, and a carbobetaine structure is a betaine structure in which a negative charge is dissociated from a carboxy group.

(Structural unit a2)
In one or more embodiments, from the viewpoint of improving cleaning properties, the structural unit a2 is preferably at least one type of structural unit selected from the structural unit represented by the following formula (II), the structural unit represented by the following formula (III), and the structural unit represented by the following formula (IV): The structural unit a2 may be one type or a combination of two or more types.

In formula (II), R ⁷ , R ⁸ and R ⁹ are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group; X ² represents O or NH; R ¹⁰ represents a hydrocarbon group; and X ³ represents a hydrogen atom or a hydroxyl group.
In formula (II), R ⁷ and R ⁸ are preferably hydrogen atoms from the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties. R ⁹ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties. X ² is preferably O (oxygen atom), from the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties. The hydrocarbon group of R ¹⁰ may be linear, branched, or cyclic. From the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties, the hydrocarbon group of R ¹⁰ is preferably a hydrocarbon group having 1 to 22 carbon atoms, more preferably an alkylene group having 1 to 22 carbon atoms, an arylene group having 6 to 22 carbon atoms, or an aralkylene group having 7 to 22 carbon atoms, and even more preferably an alkylene group having 1 to 22 carbon atoms or an aralkylene group having 7 to 22 carbon atoms. The number of carbon atoms in the alkylene group is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, and is preferably 22 or less, more preferably 18 or less, even more preferably 14 or less, even more preferably 10 or less, and even more preferably 6 or less. Specific examples of ^R10 include alkylene groups such as butylene group, _and aralkylene groups such as _-CH2 - _C6H4- .

In formula (III), R ¹¹ , R ¹² and R ¹³ are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group, and R ¹⁴ represents a hydrogen atom, a hydroxyl group, a hydrocarbon group or an alkoxy group.
In formula (III), R ¹¹ and R ¹² are preferably hydrogen atoms from the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties. R ¹³ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties. The hydrocarbon group of R ¹⁴ may be either a straight chain or a branched chain. From the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties, examples of the hydrocarbon group of R ¹⁴ include an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms. From the viewpoints of improving cleaning properties, examples of the alkoxy group of ^{R 14} include an alkoxy group having 1 to 4 carbon atoms. From the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties, examples of the alkoxy group of R ¹⁴ include an alkoxy group having 1 to 4 carbon atoms. From the viewpoints of availability of the unsaturated monomer, polymerizability of the monomer, and cleaning properties, examples of the hydrogen atom are preferred.

In formula (IV), R ¹⁵ , R ¹⁶ and R ¹⁷ are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group; n represents an integer of 2 to 12.
In formula (IV), R ¹⁵ , R ¹⁶ and R ¹⁷ are preferably a hydrogen atom from the viewpoint of improving cleaning properties. n is preferably an integer of 2 to 12, more preferably an integer of 3 to 10, and even more preferably an integer of 3 to 6, from the viewpoint of improving cleaning properties.

In one or more embodiments, the constitutional unit represented by formula (II) may be a constitutional unit derived from at least one monomer selected from butyl methacrylate (BMA), hydroxypropyl methacrylate (HPMA), 2-ethylhexyl methacrylate (EHMA), lauryl methacrylate (LMA), stearyl methacrylate (SMA), benzyl methacrylate (BzMA), and (meth)acrylic acid alkyl ester. In the present disclosure, "(meth)acrylic acid" means acrylic acid or methacrylic acid.
In one or a plurality of embodiments, examples of the constitutional unit represented by formula (III) include constitutional units derived from styrene (St) and α-methylstyrene (αMSt).
In one or more embodiments, the constitutional unit represented by formula (IV) may be a constitutional unit derived from vinylpyrrolidone (VP).

When component A is a copolymer containing structural units a1 and a2, in one or more embodiments, from the viewpoint of improving cleaning properties, component A may be at least one selected from 2-methacryloyloxyethyl phosphorylcholine/butyl methacrylate copolymer (MPC/BMA), 2-methacryloyloxyethyl phosphorylcholine/stearyl methacrylate copolymer (MPC/SMA), 2-methacryloyloxyethyl phosphorylcholine/benzyl methacrylate copolymer (MPC/BzMA), 2-methacryloyloxyethyl phosphorylcholine/styrene copolymer (MPC/St), 2-methacryloyloxyethyl phosphorylcholine/α-methylstyrene copolymer (MPC/αMSt), 2-methacryloyloxyethyl phosphorylcholine/vinylpyrrolidone copolymer (MPC/VP), and N-methacryloyloxyethyl-N,N-dimethylammonium-α-N-methylcarboxybetaine (GLBT)/methacrylic acid alkyl ester copolymer.

When component A is a copolymer containing structural units a1 and a2, the total content of structural units a1 and a2 in all structural units of component A is preferably 90 to 100 mol %, more preferably 95 to 100 mol %, and even more preferably 99 to 100 mol %, from the viewpoint of improving cleaning properties.

When component A is a copolymer containing structural units a1 and a2, the molar ratio of structural units a1 to structural units a2 (a1/a2) in all structural units of component A is preferably 10/90 or more, more preferably 20/80 or more, even more preferably 30/70 or more, even more preferably 40/60 or more, even more preferably 50/50 or more, even more preferably 60/40, from the viewpoint of improving cleaning properties, and from the same viewpoint, is preferably 98/2 or less, more preferably 95/5 or less.

(Structural unit a3)
In one or more embodiments, from the viewpoint of improving cleaning properties, the structural unit a3 is preferably a structural unit having at least one group selected from a primary amino group, a secondary amino group, a tertiary amino group, a quaternary ammonium group, and salts thereof. The structural unit a3 may be one type, or a combination of two or more types. From the viewpoint of improving cleaning properties, examples of monomers forming the structural unit a3 include salts of 2-hydroxy-3-(methacryloyloxy)propyltrimethylammonium, salts of 2-hydroxy-3-(acryloyloxy)propyltrimethylammonium, salts of [2(methacryloyloxy)ethyl]trimethylammonium, salts of [2(acryloyloxy)ethyl]trimethylammonium, salts of methacryloyloxyethyldimethylethylaminium (MOEDES), salts of methacryloylethyltrimethylaminium (MOETMA), 2-aminoethyl methacrylate (MOEA), and 2-(diethylamino)ethyl methacrylate (MOEDEA). Examples of salts include chloride (Cl ⁻ ) salts, bromide (Br ⁻ ) salts, sulfate (SO ₄ ²⁻ ) salts, etc. Specific examples of the structural unit a3 include structural units derived from 2-hydroxy-3-(methacryloyloxy)propyltrimethylammonium chloride (HMTA).

When component A is a copolymer containing structural units a1 and a3, in one or more embodiments, component A may be 2-methacryloyloxyethyl phosphorylcholine/2-hydroxy-3-(methacryloyloxy)propyltrimethylammonium chloride copolymer (MPC/HMTA) from the viewpoint of improving cleaning properties.

When component A is a copolymer containing structural units a1 and a3, the total content of structural units a1 and a3 in all structural units of component A is preferably 90 to 100 mol %, more preferably 95 to 100 mol %, and even more preferably 99 to 100 mol %, from the viewpoint of improving cleaning properties.

When component A is a copolymer containing structural units a1 and a3, the molar ratio of structural units a1 to structural units a3 (a1/a3) in all structural units of component A is preferably 10/90 or more, more preferably 20/80 or more, and even more preferably 30/70 or more, from the viewpoint of improving cleaning properties, and from the same viewpoint, is preferably 98/2 or less, and more preferably 95/5 or less.

When component A is a copolymer containing structural units a1, a2, and a3, the molar ratio of the content of structural unit a1 to the total content of structural units a2 and a3 in all structural units of component A [a1/(a2+a3)] is preferably 10/90 or more, more preferably 20/80 or more, from the viewpoint of improving cleaning properties, and from the same viewpoint is preferably 98/2 or less, more preferably 95/5 or less.

Component A may have other structural units in addition to the structural units a1, a2, and a3 described above. Examples of other structural units include acrylonitrile.

From the viewpoint of improving cleaning properties, the weight average molecular weight of component A is preferably 1,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and preferably 3,000,000 or less, more preferably 2,000,000 or less, and even more preferably 1,000,000 or less. More specifically, the weight average molecular weight of component A is preferably 1,000 or more and 3,000,000 or less, more preferably 5,000 or more and 2,000,000 or less, and even more preferably 10,000 or more and 1,000,000 or less. The weight average molecular weight of component A can be measured, for example, using gel permeation chromatography (GPC) under the conditions described in the examples.

The content of component A in the cleaning composition of the present disclosure during cleaning is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more, from the viewpoint of improving cleaning performance, and from the same viewpoint, is preferably 1% by mass or less, more preferably 0.7% by mass or less, and even more preferably 0.5% by mass or less. More specifically, the content of component A is preferably 0.001% by mass or more and 1% by mass or less, more preferably 0.005% by mass or more and 0.7% by mass or less, and even more preferably 0.01% by mass or more and 0.5% by mass or less. When component A is a combination of two or more types, the content of component A is the total content thereof.

[Component B: Water]
The water contained in the cleaning composition of the present disclosure (hereinafter also referred to as "component B") may be ion-exchanged water, RO water, distilled water, pure water, or ultrapure water. The content of component B during cleaning with the cleaning composition of the present disclosure may be the remainder excluding component A and any optional components described below that are blended as necessary.

[Component C: pH adjuster]
The cleaning composition of the present disclosure may further contain a pH adjuster (hereinafter, also referred to as "component C"). Examples of component C include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid; organic acids such as 1-hydroxy-1,1-diphosphonic acid, oxycarboxylic acids, polycarboxylic acids, aminopolycarboxylic acids, and amino acids; and basic substances such as metal salts or ammonium salts thereof, ammonia, sodium hydroxide, potassium hydroxide, and amines. Component C may be used alone or in combination of two or more types. In one or more embodiments, the content of component C in the cleaning composition of the present disclosure may be an amount such that the pH of the cleaning composition of the present disclosure is in the range of 0.5 to 5.

[Component D: Dissolution promoter]
In one or more embodiments, the cleaning agent composition of the present disclosure may further contain a dissolution promoter (component D) from the viewpoint of improving cleaning properties. Component D may be any component as long as it has properties as a reducing agent or an oxidizing agent and can dissolve cerium oxide particles. Examples of the reducing agent include polyhydroxybenzene having two or more hydroxyl groups or five-membered ring compounds containing polyhydroxyl, compounds containing an aldehyde group, and compounds containing a thiol group. Specific examples of the reducing agent include at least one selected from ascorbic acid, thiourea, thioglycolic acid, thiodiglycolic acid, thioglycerol, hydroquinone, pyrogallol, catechol, methylcatechol, resorcinol, reducing sugars such as glucose, hydrogen peroxide, gallic acid, oxalic acid, and formic acid. Examples of the oxidizing agent include permanganic acid, iodic acid, periodic acid, hydrogen peroxide, nitric acid, bromic acid, sulfuric acid, peroxosulfuric acid, hypochlorous acid, and salts thereof. Among these, hydrogen peroxide is preferred from the viewpoints of organic residue reduction, ease of availability, and cost. Component D may be one type or a combination of two or more types.

From the viewpoint of improving cleaning performance, the content of component D during cleaning with the cleaning composition of the present disclosure is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, even more preferably 0.01% by mass or more, and preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less. More specifically, the content of component D is preferably 0.001% by mass or more and 3% by mass or less, more preferably 0.005% by mass or more and 2% by mass or less, and even more preferably 0.01% by mass or more and 1% by mass or less. When component D is a combination of two or more types, the content of component D refers to the total content thereof.

[Other ingredients]
The cleaning agent composition of the present disclosure may contain other components as necessary, in addition to the above-mentioned Components A, B, C, and D. Examples of other components include water-soluble polymers other than Component A, surfactants other than Component A, chelating agents, solubilizing agents, preservatives, rust inhibitors, bactericides, antibacterial agents, silicone-based defoamers, antioxidants, esters, alcohols, and the like.
The content of other components in the cleaning agent composition of the present disclosure during cleaning is preferably 0 mass% or more and 2 mass% or less, more preferably 0 mass% or more and 1.5 mass% or less, even more preferably 0 mass% or more and 1.3 mass% or less, and still more preferably 0 mass% or more and 1 mass% or less, from the viewpoint of not impairing the effects of the present disclosure.

[Method of producing the cleaning composition]
The cleaning composition of the present disclosure can be produced, for example, by blending component A, component B, and optional components (component C, component D, other components) as needed by a known method. For example, the cleaning composition of the present disclosure can be produced by blending at least component A and component B. Thus, in one aspect, the present disclosure relates to a method for producing a cleaning composition, which includes a step of blending at least component A and component B. In the present disclosure, "blending" includes mixing component A, component B, and optional components (component C, component D, other components) as needed simultaneously or in any order. In the method for producing a cleaning composition of the present disclosure, the blending amount of each component can be the same as the content of each component of the cleaning composition of the present disclosure described above.

In this disclosure, "the content of each component of the detergent composition at the time of cleaning" refers, in one or more embodiments, to the content of each component of the detergent composition used in the cleaning process, i.e., at the time when the detergent composition starts to be used for cleaning (at the time of use).

The cleaning composition of the present disclosure may be prepared as a concentrate in which the amount of water (component B) is reduced to the extent that separation, precipitation, etc. do not occur and storage stability is not impaired. The cleaning composition concentrate is preferably a concentrate with a dilution ratio of 10 times or more from the viewpoint of transportation and storage, and is preferably a concentrate with a dilution ratio of 100 times or less from the viewpoint of storage stability. The cleaning composition concentrate can be used by diluting with water so that each component has the above-mentioned content (i.e., the content at the time of cleaning) at the time of use. Furthermore, the cleaning composition concentrate can also be used by adding each component separately at the time of use. In the present disclosure, "at the time of use" or "at the time of cleaning" of the cleaning composition concentrate refers to the state in which the cleaning composition concentrate is diluted.

From the viewpoint of improving cleaning performance, the pH of the cleaning composition of the present disclosure during cleaning is 0.5 or more, preferably 0.7 or more, more preferably 1.0 or more, even more preferably 1.5 or more, and 5.0 or less, preferably 4.5 or less, more preferably 4.0 or less, more preferably 3.5 or less, more preferably 3.0 or less, and more preferably 2.5 or less. More specifically, the pH of the cleaning composition of the present disclosure during cleaning is 0.5 or more and 5 or less, preferably 0.7 or more and 4.5 or less, more preferably 1.0 or more and 4.0 or less, more preferably 1.0 or more and 3.0 or less, and even more preferably 1.5 or more and 2.5 or less. In this disclosure, the "pH during cleaning" refers to the pH of the cleaning composition at 25°C when it is used (after dilution), and can be measured using a pH meter. Specifically, it can be measured by the method described in the examples.

[Substrate (substrate to be cleaned)]
In one or more embodiments, the cleaning composition of the present disclosure can be used for cleaning a substrate after polishing using a polishing composition containing cerium oxide particles, and for cleaning a substrate on which foreign matter derived from cerium oxide abrasive grains is attached to the substrate surface. In one or more embodiments, the polishing composition of the present disclosure is suitably used for cleaning a substrate having a silicon oxide film formed on the surface of a silicon wafer, after the silicon oxide film is polished with a polishing composition containing cerium oxide particles. The cerium oxide particles may be positively charged cerium oxide particles (positively charged ceria) or negatively charged cerium oxide particles (negatively charged ceria). The chargeability of the cerium oxide particles can be confirmed, for example, by measuring the electric potential (surface potential) on the surface of the abrasive grains obtained by an electroacoustic method (ESA method: Electrokinetic Sonic Amplitude). The surface potential can be measured, for example, using a "Zeta Probe" (manufactured by Kyowa Interface Science Co., Ltd.).
The cleaning composition of the present disclosure can be used for substrates of various materials and shapes. For example, a substrate polished with a polishing composition containing cerium oxide particles, or a substrate having foreign matter derived from cerium oxide abrasive grains attached to the substrate surface can be used. For example, a substrate having a silicon oxide film on its surface polished with a polishing composition containing cerium oxide particles is preferably used, and for example, a substrate for semiconductor devices such as a silicon wafer substrate, a substrate having a silicon oxide film formed on the surface of a silicon wafer, a glass substrate, or a ceramic substrate is preferably used. Therefore, in another aspect, the present disclosure relates to the use of the cleaning composition of the present disclosure for cleaning a substrate for semiconductor devices.

The surface material of the substrate is not particularly limited, and for example, single crystal silicon, polycrystalline silicon, amorphous silicon, thermal silicon oxide film, non-doped silicate glass film, phosphorus-doped silicate glass film, boron-doped silicate glass film, phosphorus-doped boron-doped silicate glass film, tetraethyl orthosilicate (TEOS) film, plasma CVD oxide film, silicon nitride film, silicon carbide film, silicon oxide carbide film, or silicon oxide carbide nitride film is preferably used. Furthermore, glass, quartz, crystal, ceramics, etc. are also preferably used. In one or more embodiments, the substrate may be a substrate composed of these materials alone, or may be a substrate patterned or laminated with two or more materials having a certain distribution.

[Substrate cleaning method]
In one aspect, the present disclosure relates to a method for cleaning a substrate (substrate to be cleaned) polished with a polishing composition containing cerium oxide particles (hereinafter also referred to as the "cleaning method of the present disclosure"). In one or more embodiments, the cleaning method of the present disclosure includes a step of contacting the substrate with the cleaning composition of the present disclosure. The substrate may be any of the above-mentioned substrates. In one or more embodiments, the cleaning method of the present disclosure is suitable for cleaning a substrate having a silicon oxide film on its surface after polishing the substrate with a polishing composition containing cerium oxide particles.

Methods (cleaning methods) for contacting a substrate with the cleaning composition of the present disclosure include, for example, cleaning using a pad, brush cleaning, immersion cleaning, ultrasonic cleaning, swing cleaning, spray cleaning, cleaning using rotation such as a spinner, and the like, which may be performed alone or in combination. In particular, the cleaning composition of the present disclosure is preferably used for cleaning using a pad, as described above. Thus, in one or more embodiments, the cleaning method of the present disclosure includes pressing a pad against the surface of a substrate, and moving the substrate and the pad relative to each other while supplying the cleaning composition of the present disclosure between the substrate and the pad. Examples of pads include a polyurethane foam pad, a nonwoven fabric, a fluororesin, a suede pad (buff), and the like.

When the cleaning composition of the present disclosure is a concentrate, in one or more embodiments, the cleaning method of the present disclosure may further include a dilution step of diluting the concentrate of the cleaning composition. In one or more embodiments, the cleaning method of the present disclosure preferably includes a step of contacting a substrate with the cleaning composition of the present disclosure, rinsing with water, and drying. The cleaning method of the present disclosure can efficiently remove cerium oxide particles remaining on the substrate surface. In the cleaning method of the present disclosure, it is preferable to irradiate ultrasonic waves when the cleaning composition of the present disclosure comes into contact with the substrate, since the cleaning power of the cleaning composition of the present disclosure is easily exerted, and it is more preferable that the ultrasonic waves are relatively strong. From the same viewpoint, the ultrasonic irradiation conditions are preferably 20 to 2,000 kHz, more preferably 40 to 2,000 kHz, and even more preferably 40 to 1,500 kHz.

[Method of manufacturing a substrate for semiconductor devices]
In one aspect, the present disclosure relates to a method for manufacturing a substrate for a semiconductor device (hereinafter also referred to as the "substrate manufacturing method of the present disclosure"), which includes a step of cleaning a substrate (substrate to be cleaned) polished with a polishing composition containing cerium oxide particles using the cleaning method of the present disclosure. The substrate may be the above-mentioned substrate. The cleaning method and cleaning conditions in the cleaning step of the substrate manufacturing method of the present disclosure may be the same as those in the cleaning step of the cleaning method of the present disclosure. In one or more embodiments, the substrate manufacturing method of the present disclosure may include (1A) a step of performing CMP using a polishing composition containing cerium oxide particles, and (2A) a step of cleaning the substrate polished in step (1A) using the cleaning method of the present disclosure. In one or more other embodiments, the substrate manufacturing method of the present disclosure may include (1B) a step of polishing a substrate having a silicon oxide film on its surface with a polishing composition containing cerium oxide particles, and (2B) a step of cleaning the substrate polished in step (1B) with the cleaning agent composition of the present disclosure.

A specific example of a process for carrying out CMP will be described below.
First, a silicon substrate is exposed to oxygen in an oxidation furnace to form a silicon substrate including a silicon dioxide layer. Next, a silicon nitride (Si ₃ N ₄ ) film is formed on the silicon dioxide layer side of the silicon substrate, for example, on the silicon dioxide layer, for example, by CVD (chemical vapor deposition). Next, a substrate including the silicon substrate thus obtained and a silicon nitride film disposed on one main surface side of the silicon substrate, for example, a substrate including a silicon substrate and a silicon nitride film disposed on one main surface of the silicon substrate, or a substrate including a silicon substrate and a silicon nitride film disposed on one main surface of the silicon substrate, is formed with a trench penetrating the silicon nitride film and having a bottom reaching into the silicon substrate by photolithography. Next, a silicon oxide (SiO ₂ ) film for filling the trench is formed by CVD using, for example, silane gas and oxygen gas, and the trench is filled with silicon oxide, thereby obtaining a polished substrate in which the trench and the silicon nitride film are covered with the silicon oxide film. By forming the silicon oxide film, the trench is filled with silicon oxide of the silicon oxide film, and the surface of the silicon nitride film opposite to the surface on the silicon substrate side is covered with the silicon oxide film. The surface of the silicon oxide film opposite to the surface on the silicon substrate side formed in this manner has a step formed corresponding to the unevenness of the underlying layer. Next, the silicon oxide film is polished by a CMP method with a cerium oxide slurry until at least the surface opposite to the surface on the silicon substrate side of the silicon nitride film is exposed, and more preferably, the silicon oxide film is polished until the surfaces of the silicon oxide film and the silicon nitride film are flush with each other.

The substrate manufacturing method of the present disclosure uses the cleaning composition of the present disclosure to clean the substrate, thereby reducing foreign matter such as abrasive grains and polishing debris remaining on the substrate surface after CMP and suppressing the occurrence of defects in subsequent processes due to remaining foreign matter, making it possible to manufacture highly reliable substrates for semiconductor devices. Furthermore, by carrying out the cleaning method of the present disclosure, it becomes easier to clean residues such as abrasive grains and polishing debris from the substrate surface after CMP, thereby shortening the cleaning time and improving the manufacturing efficiency of substrates for semiconductor devices.

The present disclosure will be explained in detail below with reference to examples, but the present disclosure is not limited to these examples.

1. Preparation of cleaning compositions (Examples 1 to 22, Comparative Examples 1 to 2, and Reference Examples 1 to 4)
The water-soluble polymer (component A) shown in Table 1 was mixed with water (component B) to give a predetermined concentration, and the pH was adjusted using a pH adjuster (component C) as necessary to prepare cleaning compositions of Examples 1 to 20, Comparative Examples 1 and 2, and Reference Examples 1 to 4.
The water-soluble polymer (component A) and dissolution promoter (component D) shown in Table 2 were mixed with water (component B) to give predetermined concentrations, and the pH was adjusted using a pH adjuster (component C) as necessary to prepare the cleaning compositions of Examples 8 to 13 and 21 to 22. As the pH adjuster (component C), a 1 mass % aqueous sulfuric acid solution or 1 N ammonia water was used.
The contents of components A and D shown in Tables 1 and 2 are the contents (mass%, active content) of the cleaning composition at the time of use. The pH shown in Tables 1 and 2 is the pH of the cleaning composition at 25°C.

The following components were used in each cleaning composition.
(Component A)
MPC polymer [product name: Lipidure-HM, NOF Corporation, weight average molecular weight: 100,000]
MPC/BMA copolymer [product name: Lipidure-PMB, NOF Corporation, molar ratio (MPC/BMA): 80/20, weight average molecular weight: 600,000]
MPC/HMTA copolymer [product name: Lipidure-C, NOF Corporation]
MPC/αMSt copolymer [Kao Corporation, molar ratio (MPC/αMSt): 80/20, weight average molecular weight: 100,000]
MPC/VP copolymer [Kao Corporation, molar ratio (MPC/VP): 80/20, weight average molecular weight: 100,000]
GLBT homopolymer [p-MEB, manufactured by Osaka Organic Chemical Industry Co., Ltd., weight average molecular weight 600,000]
GLBT/methacrylic acid alkyl ester copolymer [RAM Resin-4000, manufactured by Osaka Organic Chemical Industry Co., Ltd., weight average molecular weight 50,000]
(Non-Component A)
Polyacrylic acid (Kao Corporation, weight average molecular weight 23,000)
(Component B)
Water [ultrapure water produced using a continuous pure water production system (Pure Conti PC-2000VRL type) and subsystem (Macace KC-05H type) manufactured by Kurita Water Industries Ltd.]
(Component C)
Nitric acid [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.]
Ammonia water [Fujifilm Wako Pure Chemical Industries, Ltd.]
(Component D)
Ascorbic acid [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.]
Thiourea [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.]
Thioglycolic acid [Tokyo Chemical Industry Co., Ltd.]
Catechol [Tokyo Chemical Industry Co., Ltd.]
Hydrogen peroxide [ADEKA]
Thioglycerol

2. Method for measuring various parameters [pH of cleaning composition]
The pH of the cleaning composition at 25° C. is a value measured using a pH meter (HM-30G, manufactured by DKK-TOA Corporation) and is the value measured one minute after immersing the electrode of the pH meter in the cleaning composition.

[Weight average molecular weight of water-soluble polymer (component A)]
The weight average molecular weight of the water-soluble polymer (component A) was calculated based on peaks in a chromatogram obtained by applying gel permeation chromatography (GPC) under the following conditions.
Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated type)
Column: Two TSKgel α-M columns (manufactured by Tosoh Corporation) connected in series Eluent: 0.15 mol _{Na 2} SO ₄ /1% CH ₃ COOH/water Flow rate: 1.0 mL/min
Column temperature: 40°C
Detector: RI Detector standard material: Pullulan

3. Evaluation of Cleaning Compositions The cleaning compositions prepared in Examples 1 to 22, Comparative Examples 1 and 2, and Reference Examples 1 to 4 were used to carry out the following evaluations.

[Preparation of substrate for surface defect evaluation]
A silicon wafer (8 inches) having a silicon oxide film of 2000 nm thickness formed on one side by TEOS-plasma CVD was used as a substrate for measuring surface defects, and the number of surface defects was measured by carrying out CMP polishing and cleaning.
(Polishing method)
Cerium oxide particles (average primary particle size: 100 nm) and ammonium polyacrylate were mixed in water to prepare polishing compositions with concentrations of 0.5% by mass and 0.4% by mass. The polishing apparatus used was "F-REX200" manufactured by Ebara Corporation, and the polishing pad used was "IC1000/SUBA400" laminated pad manufactured by Nitta Haas Co., Ltd. The polishing pad was attached to the platen of the polishing apparatus, the substrate was set on the holder, and the holder was placed on the polishing pad so that the surface of the substrate on which the silicon oxide film was formed was facing down, that is, so that the silicon oxide film was in contact with the polishing pad. Furthermore, the load applied to the test piece was set to 3 psi, and the polishing composition was dropped at a rate of 200 mL/min onto the center of the platen to which the polishing pad was attached, while rotating the platen and the holder in the same direction at 100 rpm and 107 rpm for 1 minute to polish the silicon oxide film substrate.
(Cleaning process 1)
After the above polishing step, the silicon oxide film substrate after polishing was used on the same platen and the cleaning step 1 was carried out by the following method. The holder was placed on the polishing pad so that the surface of the substrate on which the silicon oxide film was formed was facing down, i.e., so that the silicon oxide film was in contact with the polishing pad. Furthermore, the load on the test piece was set to 1.5 psi, and the prepared cleaning compositions of Examples 1 to 22, Comparative Examples 1 to 2, and Reference Examples 1 to 4 were dropped at a rate of 200 mL/min onto the center of the platen to which the pad was attached, while rotating the platen and the holder in the same direction at 107 rpm and 100 rpm for 30 seconds, respectively, to perform cleaning.
(Washing process 2)
After the above polishing process, roll brush cleaning was performed for 40 seconds and pencil brush cleaning was performed for three scans using ultrapure water in a cleaning unit installed in the "F-REX200." After that, the substrate was dried by spin drying.

[Evaluation of number of surface defects (cleanability)]
The number of defects (defect count) of 70 nm or more was measured for the substrates obtained by CMP polishing and cleaning using a Topcon Corporation "WM-10". The results are shown in Tables 1 and 2. The fewer the number of surface defects, the greater the effect of removing foreign matter from the substrate surface, and the better the cleaning performance can be evaluated. In this test, the number of defects cleaned with the cleaning composition described in Example 1 was set to 100, and the data was expressed as a relative value.

As shown in Table 1, the cleaning compositions of Examples 1 to 7 and 14 to 20 had fewer surface defects and were superior in cleaning properties compared to the cleaning compositions of Comparative Examples 1 to 2, which had a pH within the specified range but did not contain a water-soluble polymer (component A), and Reference Examples 1 to 4, which contained a water-soluble polymer (component A) but did not have a pH within the specified range.

As shown in Table 2, the cleaning compositions of Examples 8 to 11 containing MPC (component A) and a dissolution promoter (component D) had fewer surface defects and better cleaning properties than Example 3 containing MPC (component A) but not a dissolution promoter (component D). Examples 12 to 13 containing MPC/BMA (component A) and a dissolution promoter (component D) had fewer surface defects and better cleaning properties than Example 4 containing MPC/BMA (component A) but not a dissolution promoter (component D). The cleaning compositions of Examples 21 to 22 containing GLBT (component A) and a dissolution promoter (component D) had fewer surface defects and better cleaning properties than Examples 14 to 15 containing GLBT (component A) but not a dissolution promoter (component D).

The cleaning composition disclosed herein is useful as a cleaning composition used in the manufacturing process of substrates for semiconductor devices, and can shorten the cleaning process for substrates having cerium oxide particles attached thereto and improve the performance and reliability of the substrates for semiconductor devices manufactured, thereby improving the productivity of semiconductor devices.

Claims (11)

A cleaning agent composition for cleaning a semiconductor device substrate polished with a polishing composition containing cerium oxide particles, comprising:
The composition contains a water-soluble polymer (component A) containing at least one structural unit a1 selected from a structural unit represented by the following formula (I) and a structural unit represented by the following formula (V), and water (component B),
A cleaning composition for use on a semiconductor device substrate, the cleaning composition having a pH during use of 0.5 or more and 2.5 or less.

In formula (I), ^R1 , ^R2 , ^R3 , ^R4 , ^R5 and ^R6 are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group; ^X1 is O or NH; and ^Y1 and ^Y2 are the same or different and each represents an alkylene group having 1 to 4 carbon atoms.

In formula (V), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ and R ²² are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group, X ⁴ is O or NH, and Y ³ and Y ⁴ are the same or different and each represents an alkylene group having 1 to 4 carbon atoms. The cleaning composition according to claim 1, wherein the structural unit represented by formula (I) is a structural unit derived from a monomer containing a methacryloyloxyethyl phosphobetaine structure. The cleaning composition according to claim 1 or 2, wherein the structural unit represented by formula (V) is a structural unit derived from a monomer containing a methacryloyloxyethyl carbobetaine structure. 4. The cleaning agent composition according to any one of claims 1 to 3, wherein Component A is a copolymer comprising at least one structural unit a1 selected from the structural units represented by Formula (I) and the structural units represented by Formula (V), and at least one structural unit a2 selected from the structural units represented by Formula (II) below, the structural units represented by Formula (III) below, and the structural units represented by Formula (IV) below:

In formula (II), R ⁷ , R ⁸ and R ⁹ are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group; X ² represents O or NH; R ¹⁰ represents a hydrocarbon group; and X ³ represents a hydrogen atom or a hydroxyl group.
In formula (III), R ¹¹ , R ¹² and R ¹³ are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group, and R ¹⁴ represents a hydrogen atom, a hydroxyl group, a hydrocarbon group or an alkoxy group having 1 to 4 carbon atoms.
In formula (IV), R ¹⁵ , R ¹⁶ and R ¹⁷ are the same or different and each represents a hydrogen atom, a methyl group or an ethyl group; n represents an integer of 2 to 12. The cleaning composition according to any one of claims 1 to 4, wherein component A is a copolymer containing at least one structural unit a1 selected from the structural units represented by formula (I) and the structural units represented by formula (V), and a structural unit a3 having at least one group selected from a primary amino group, a secondary amino group, a tertiary amino group, a quaternary ammonium group, and salts thereof. The cleaning composition according to any one of claims 1 to 5, further comprising a pH adjuster. The cleaning composition according to any one of claims 1 to 6, further comprising a solubility enhancer. The cleaning composition according to any one of claims 1 to 7, wherein the substrate is a substrate having a silicon oxide film. The cleaning composition according to any one of claims 1 to 8, which is used for cleaning a substrate by contacting the substrate with a pad. A method for cleaning a substrate polished with a polishing composition containing cerium oxide particles, comprising:
10. A method for cleaning a substrate, comprising: pressing a pad against a surface of the substrate; and moving the substrate and the pad relative to each other while supplying the cleaning agent composition according to claim 1 between the substrate and the pad. A method for manufacturing a substrate for a semiconductor device, comprising a step of cleaning a substrate polished with a polishing composition containing cerium oxide particles using the cleaning method according to claim 10.