Cleaning liquid, cleaning method, and method for manufacturing semiconductor element

Abstract

The present invention provides a cleaning liquid which is capable of effectively removing abrasive grains and organic components that are adhered to an object to be cleaned, a cleaning method which uses the cleaning liquid, and a method for manufacturing a semiconductor element.　The cleaning liquid is for abrasive grain removal and comprises a fluoropolymer having an acidic group, and water.

Description

Cleaning solution, cleaning method, and semiconductor element manufacturing method

[0001] The present invention relates to a cleaning solution, a cleaning method, and a method for manufacturing a semiconductor device.

[0002] In semiconductor devices, such as semiconductor devices, the integration density is increasing to improve performance, resulting in miniaturization of semiconductor elements such as transistors and multilayer wiring. One example of a semiconductor element manufacturing method involves sequentially depositing a conductive film, an insulating film, a resist film, etc. on a semiconductor substrate such as a silicon wafer, forming a circuit pattern through processes such as lithography and etching, and then depositing an oxide film, followed by planarization using chemical mechanical polishing (CMP). Furthermore, a new layer may be stacked on the flat surface to form a multilayer semiconductor element. In CMP, polishing is performed using a slurry-like abrasive containing abrasive particles (also known as abrasive grains). In CMP of silicon compound films such as silicon dioxide films and silicon nitride films, cerium compound-containing particles are preferably used as abrasive grains to improve the polishing rate. After the CMP process, unwanted components such as abrasive components (e.g., abrasive grains and organic components such as polymers) and polishing debris may be present on the surface of the semiconductor element. Therefore, after the CMP process, the semiconductor element is typically cleaned with a cleaning solution. Generally, cerium compound-containing particles are difficult to remove because they form bonds with the surface of silicon compound films such as silicon dioxide films and silicon nitride films during the CMP process, or they adhere strongly to the surface due to the attractive force of the zeta potential under acidic conditions. For this reason, cleaning has traditionally been performed using strong chemicals such as diluted hydrofluoric acid and sulfuric acid / hydrogen peroxide, but efforts are underway to develop cleaning solutions that are easier to handle.

[0003] Patent Document 1 discloses an aqueous cleaning solution containing a fluorine-containing inorganic acid (excluding hydrogen fluoride) or a salt thereof. Patent Document 2 discloses a post-CMP cleaning composition containing a specific organic acid, a specific fluoride, a specific additive, etc. Patent Documents 1 and 2 do not disclose an embodiment containing a fluoropolymer having an acidic group.

[0004] International Publication No. 2018 / 180256 Japanese Patent Application Laid-Open No. 2022-9467

[0005] From the viewpoint of improving the production efficiency of semiconductor devices, it is desirable to be able to effectively remove abrasive particles bonded to or attached to the substrate surface after the CMP process.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a cleaning liquid that can effectively remove abrasive grains and organic components adhering to an object to be cleaned, a cleaning method using the cleaning liquid, and a method for manufacturing semiconductor elements.

[0007] The present disclosure provides the following cleaning solution for removing abrasive grains, a cleaning method, and a method for manufacturing semiconductor devices. [1] A cleaning solution for removing abrasive grains, comprising a fluoropolymer having an acidic group and water. [2] The cleaning solution of [1], wherein the fluoropolymer has a unit represented by the following formula (1): -[CR １ R ２ -CR ３ {R ｆ１ -(Z) ｎ}]-...(1) In formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, or a chlorine atom; R ３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group, and R ｆ１ is a linear or branched fluoroalkyl chain which may contain an etheric oxygen atom, or R ２ and R ｆ１ are linked to form a single linear or branched fluoroalkyl chain which may contain an etheric oxygen atom between carbon atoms, or R ３ and R ｆ１ are linked together to form a single linear or branched fluoroalkyl chain which may contain an etheric oxygen atom between carbon atoms, and Z is —SO ３ H, -SO ３ Z １ , -CO ２ H, -CO ２ Z １ , -PO(OH) ２ , -PO ３ (OZ １ )２ or OH, and Z １ is a cation, and n is 1 or 2. [3] The cleaning solution according to [1] or [2] above, wherein the fluoropolymer has a unit represented by the following formula (1A): -[CR １ R ２ -CR ３ (R ｆ１ -Z)]-...(1A) In formula (1A), R １ and R ２ are each independently a hydrogen atom, a fluorine atom or a chlorine atom, ３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group, and R ｆ１ is a linear or branched fluoroalkylene group which may contain an etheric oxygen atom, and R ｆ１ is a fluoroalkylene group containing no etheric oxygen atom, the number of carbon atoms is 1 to 10, and Z is —SO ３ H, -SO ３ Z １ , -CO ２ H, -CO ２ Z １ , -PO(OH) ２ , -PO ３ (OZ １ ) ２ or OH, and Z １ is a cation. [4] R １ , R ２ and R ３are fluorine atoms. [5] The cleaning solution of any of [1] to [4] above, wherein the concentration of acidic groups contained in 1 g of the fluoropolymer is 0.3 to 4.0 mmol / g. [6] The cleaning solution of any of [1] to [5] above, further comprising a reducing compound. [7] The cleaning solution of [6] above, wherein the reducing compound comprises at least one selected from the group consisting of gallic acid, gallic acid esters, pyrogallol, catechol, resorcinol, ascorbic acid, uric acid, diphosphorous acid, dithionic acid, thiosulfuric acid, oxalic acid, hydrogen peroxide, and hydroquinone. [8] The cleaning solution of any of [1] to [7] above, further comprising at least one complexing agent, which is an organic compound having a molecular weight of 1,000 g / mol or less and having two or more substituents selected from a carboxyl group, an amino group, a phosphoryl group, a sulfonic acid group, and a hydroxyl group in the molecule. [9] The cleaning solution according to any one of [1] to [8] above, further comprising at least one heterocyclic aromatic compound selected from the group consisting of imidazole compounds, pyrazole compounds, thiazole compounds, and triazole compounds.

[10] The cleaning solution according to any one of [1] to [9] above, further comprising 0.001% by mass to 30% by mass of the fluoropolymer.

[11] The cleaning solution according to [6] or [7] above, further comprising 0.001% by mass to 30% by mass of the reducing compound.

[12] The cleaning solution according to any one of [1] to

[11] above, having a pH of 1 to 5.

[13] The cleaning solution according to

[12] above, further comprising at least one acid selected from the group consisting of nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and condensed phosphoric acid.

[14] The cleaning solution according to any one of [1] to

[11] above, having a pH of 8 to 12.

[15] The cleaning solution of

[14] above, further comprising at least one selected from the group consisting of ammonium hydroxide, choline, hydroxyamine, monoethanolamine, diethanolamine, and triethanolamine.

[16] The cleaning solution of any of [1] to

[15] above, wherein the abrasive grains comprise cerium compound-containing particles.

[17] The cleaning solution of any of [1] to

[16] above, which is used to clean an object having abrasive grain components and organic components attached to the exposed surface of a semiconductor substrate.

[18] The cleaning solution of

[17] above, wherein the exposed surface comprises at least one selected from the group consisting of silicon dioxide and silicon nitride.

[19] The cleaning solution according to any one of [1] to

[18] above, which is used to clean an object whose surface has been polished using an abrasive containing abrasive grains.

[20] The cleaning solution according to any one of [1] to

[19] above, wherein the average particle size of the abrasive grains is 300 nm or less.

[21] A cleaning method comprising cleaning a surface to be cleaned using the cleaning solution according to any one of [1] to

[20] above.

[22] A method for manufacturing a semiconductor element, comprising cleaning an exposed surface of a semiconductor substrate using the cleaning solution according to any one of [1] to

[20] above.

[0008] The present disclosure provides a cleaning liquid that can effectively remove abrasive grains and organic components adhering to an object to be cleaned, a cleaning method that uses the cleaning liquid, and a method for manufacturing semiconductor devices.

[0009] Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments, and other embodiments may also fall within the scope of the present invention as long as they are consistent with the spirit of the present invention. Note that, unless otherwise specified, the "to" symbol indicating a numerical range includes the numerical values ​​before and after it as the lower and upper limits. "(Meth)acrylic" is a general term for "methacrylic" and "acrylic," and this also applies to (meth)acryloyl, (meth)acrylate, etc. In addition, in this specification, the term "fluoroalkylene chain" refers to a group obtained by removing the required number of fluorine atoms and hydrogen atoms from a linear, branched, or cyclic fluoroalkane. For example, a "divalent fluoroalkylene chain" refers to a group obtained by removing a total of two fluorine atoms and two hydrogen atoms from a fluoroalkane, and is also referred to as a "fluoroalkylene group." The required number can be determined from the chemical formula.

[0010] [Cleaning Solution] The cleaning solution of the present disclosure is characterized by containing a fluoropolymer having acidic groups (hereinafter, sometimes simply referred to as "fluoropolymer") and water. In this cleaning solution, the fluoropolymer having acidic groups appropriately controls the zeta potential, inhibiting adsorption or bonding between the object to be cleaned and the abrasive component, thereby facilitating the release of abrasive particles and organic components attached to the object to be cleaned. Furthermore, the fluoropolymer adsorbs to the released abrasive components and functions as a dispersant, preventing their re-adhesion to the surface of the object to be cleaned. As a result, the abrasive components can be effectively removed from the surface of the object to be cleaned. This cleaning solution is suitable for use in removing abrasive particles, and in particular, can effectively remove abrasive particles bonded or attached to the surface of a substrate after a CMP process. This cleaning solution contains at least a fluoropolymer having acidic groups and water, and may further contain other components as long as the effects of the present invention are achieved. Below, each component that may be contained in this abrasive is described.

[0011] <Fluoropolymer Having Acidic Group> The fluoropolymer having acidic groups used in the present cleaning solution is a polymer having at least one acidic group and at least one fluorine atom in the molecule. The fluoropolymer is preferably uniform in water, and is preferably dispersible or soluble in water.

[0012] The acidic group is a proton-donating group, and specific examples thereof include a sulfonic acid group, a carboxyl group, a phosphoric acid group, a hydroxyl group, etc., and may be in the form of a salt. In addition, although it is sufficient that there is at least one fluorine atom in the molecule, from the viewpoint of cleaning effect, the proportion of fluorine atoms in the polymer represented by the following formula (I) is preferably 60% or more, more preferably 80% or more, and even more preferably substantially 100% (perfluoropolymer). Formula (I): Proportion of fluorine atoms (%) = (number of fluorine atoms) / {(number of fluorine atoms) + (number of hydrogen atoms)} × 100

[0013] Furthermore, it is sufficient that there is at least one acidic group in the fluoropolymer. From the viewpoint of excellent cleaning effect, the concentration of acidic groups in the polymer per unit mass represented by the following formula (II) is preferably 0.3 mmol / g or more, more preferably 0.8 mmol / g or more. On the other hand, although there is no particular upper limit, from the viewpoint of excellent polymer handleability, it is preferably 4.0 mmol / g or less. Formula (II): Concentration of acidic groups in polymer (mmol / g) = (molar fraction of monomer having acidic group) / [{(molar fraction of monomer having acidic group) × (molar mass of monomer having acidic group)} + Σ{(molar fraction of copolymerizable monomer) × (molar mass of copolymerizable monomer)}] × 1000

[0014] Furthermore, in terms of excellent cleaning properties and prevention of abrasive grain redeposition, the TQ value (volume flow rate value) of the fluoropolymer having sulfonic acid groups is preferably 200 to 300°C, more preferably 220 to 300°C, and particularly preferably 240 to 290°C. If the TQ value is equal to or greater than the lower limit of the above range, the fluoropolymer has a sufficient molecular weight, and particles can be effectively dispersed. If the TQ value is equal to or less than the upper limit of the above range, the solubility of the fluoropolymer is improved, and a uniform solution can be prepared as a cleaning liquid. The TQ value is an index of the molecular weight of the fluoropolymer having sulfonic acid groups. TQ value: When the above fluoropolymer is melt-extruded using a nozzle with a length of 1 mm and an inner diameter of 1 mm under the condition of an extrusion pressure of 2.94 MPa, the extrusion amount is 100 mm. ３ / sec.

[0015] Furthermore, from the viewpoint of excellent cleaning properties and prevention of abrasive grain redeposition, the number average molecular weight (Mn) of the fluoropolymer having carboxylic acid groups is preferably 1,000 or more, more preferably 1,500 or more, and particularly preferably 2,500 or more. There is no particular upper limit to the Mn of the fluoropolymer, but from the viewpoint of excellent solubility and / or dispersibility of the fluoropolymer in water, it is preferably 1,000,000 or less, more preferably 900,000 or less, and particularly preferably 800,000 or less. The Mn is a value determined by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0016] (Structural Unit (1)) The fluoropolymer preferably has a unit represented by the following formula (1) (also referred to as structural unit (1)) in terms of excellent cleaning properties, ability to prevent redeposition of abrasive grains, and solubility in water: -[CR １ R ２ -CR ３ {R ｆ１ -(Z) ｎ}]-...(1) In formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, or a chlorine atom; R ３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group, and R ｆ１ is a linear or branched fluoroalkyl chain which may contain an etheric oxygen atom, or R ２ and R ｆ１ are linked to form a single linear or branched fluoroalkyl chain which may contain an etheric oxygen atom between carbon atoms, or R ３ and R ｆ１ are linked together to form a single linear or branched fluoroalkyl chain which may contain an etheric oxygen atom between carbon atoms, and Z is —SO ３ H, -SO ３ Z １ , -CO ２ H, -CO ２ Z １ , -PO(OH) ２ , -PO ３ (OZ １ ) ２ or OH, and Z １ is a cation, and n is 1 or 2. The structural unit (1) will be explained below in three forms.

[0017] ・Embodiment (I) R ２ and R ３ is R ｆ１ A form that is not connected to R. １ and R ２ R are each independently a hydrogen atom, a fluorine atom or a chlorine atom, and from the viewpoint of superior cleaning properties, a fluorine atom or a chlorine atom is preferred, and a fluorine atom is more preferred.３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group. ２ F-, CHF ２ -, CF ３ -, CHF ２ -, CF ３ - is preferred, CF ３ From the viewpoint of superior cleaning properties, a fluorine atom, a chlorine atom, or a fluoromethyl group is preferred, a fluorine atom or a fluoromethyl group is more preferred, and a fluorine atom is even more preferred.

[0018] R ｆ１ is a linear or branched fluoroalkyl chain which may contain an ethereal oxygen atom. The ethereal oxygen atom is ｆ１ may be contained between carbon atoms constituting CR ３ The end of the bonded chain may be an ether oxygen atom, that is, an oxyfluoroalkyl chain.

[0019] (i) In the formula (1), n ​​is 1, that is, when one Z is contained in one structural unit (1), R ｆ１ We will explain about R ｆ１ The linear or branched fluoroalkyl chain containing an etheric oxygen atom between carbon atoms in the formula (I) is a fluoroalkylene group. Examples of the fluoroalkylene group include groups represented by the following formula (F1): ｆ１１ - (OR ｆ１１ ) ｍ１ -*...(F1) In formula (F1), R ｆ１１ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, m1 is an integer of 1 to 200, and * is a bond to Z.

[0020] R ｆ１１ Specific examples of the group include -CF ２ -, -CHF-; -CF ２ CF ２ -, -CHFCF ２ -, -CHFCHF-, -CH ２ CF ２ -, -CH ２CHF-; -CF ２ CF ２ CF ２ -、-CF ２ CHFCF ２ -、-CF ２ CH ２ CF ２ -、-CHFCF ２ CF ２ -、-CHFCHFCF ２ -、-CHFCHFCHF-、-CHFCH ２ CF ２ -、-CH ２ CF ２ CF ２ -、-CH ２ CHFCF ２ -、-CH ２ CH ２ CF ２ -、-CH ２ CF ２ CHF-、-CH ２ CHFCHF-、-CH ２ CH ２ CHF-、-CF(CF ３ )CF ２ -、-CF(CHF ２ )CF ２ -、-CF(CH ２ F)CF ２ -、-CF(CH ３ )CF ２ -、-CF(CF ３ )CHF-、-CF(CHF ２ )CHF-、-CF(CH ２ F)CHF-、-CF(CH ３ )CHF-、-CF(CF ３ )CH ２ -、-CF(CHF ２ )CH ２ -、-CF(CH ２ F)CH ２ -、-CF(CH ３ )CH ２ -、-CH(CF ３ )CF ２ -、-CH(CHF ２ )CF ２ -、-CH(CH ２ F)CF ２ -、-CH(CH３ )CF ２ -、-CH(CF ３ )CHF-、-CH(CHF ２ )CHF-、-CH(CH ２ F)CHF-、-CH(CH ３ )CHF-、-CH(CF ３ )CH ２ -、-CH(CHF ２ )CH ２ -、-CH(CH ２ F)CH ２ -; -CF ２ CF ２ CF ２ CF ２ -、-CHFCF ２ CF ２ CF ２ -、-CH ２ CF ２ CF ２ CF ２ -、-CF ２ CHFCF ２ CF ２ -、-CHFCHFCF ２ CF ２ -、-CH ２ CHFCF ２ CF ２ -、-CF ２ CH ２ CF ２ CF ２ -、-CHFCH ２ CF ２ CF ２ -、-CH ２ CH ２ CF ２ CF ２ -、-CHFCF ２ CHFCF ２ -、-CH ２ CF ２ CHFCF ２ -、-CF ２ CHFCHFCF ２ -、-CHFCHFCHFCF ２ -、-CH ２ CHFCHFCF ２ -、-CF ２ CH ２ CHFCF ２ -、-CHFCH２ CHFCF ２ -、-CH ２ CH ２ CHFCF ２ -、-CF ２ CH ２ CH ２ CF ２ -、-CHFCH ２ CH ２ CF ２ -、-CH ２ CH ２ CH ２ CF ２ -、-CHFCH ２ CH ２ CHF-、-CH ２ CH ２ CH ２ CHF-、-CF ２ C(CF ３ )FCF ２ -; -CF ２ CF ２ CF ２ CF ２ CF ２ -、-CHFCF ２ CF ２ CF ２ CF ２ -、-CH ２ CHFCF ２ CF ２ CF ２ -、-CF ２ CHFCF ２ CF ２ CF ２ -、-CHFCHFCF ２ CF ２ CF ２ -、-CF ２ CH ２ CF ２ CF ２ CF ２ -、-CHFCH ２ CF ２ CF ２ CF ２ -、-CH ２ CH ２ CF ２ CF ２ CF ２ -、-CF ２ CF ２ CHFCF２ CF ２ -, -CHFCF ２ CHFCF ２ CF ２ -, -CH ２ CF ２ CHFCF ２ CF ２ -, -CH ２ CF ２ CF ２ CF ２ CH ２ -, -CF ２ C (C ２ F ５ ) FCF ２ -; -CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ -, -CF ２ CF ２ CHFCHFCF ２ CF ２ -, -CHFCF ２ CF ２ CF ２ CF ２ CF ２ -, -CHFCHFCHFCHFCHFCHF-, -CHFCF ２ CF ２ CF ２ CF ２ CH ２ -, -CH ２ CF ２ CF ２ CF ２ CF ２ CH ２ - etc.

[0021] Multiple R ｆ１１ may be the same or different. From the viewpoint of superior cleaning properties, R ｆ１１ is preferably a perfluoroalkylene group. ｆ１１ The number of carbon atoms in the alkyl group is preferably 1 to 4, and more preferably 2 or 3. m1 may be 1 to 200, and is preferably 1 to 150, and more preferably 1 to 120, from the viewpoint of superior cleanability.

[0022] R ｆ１The linear or branched fluoroalkyl chain containing an etheric oxygen atom between carbon atoms in the formula (F1) is an oxyfluoroalkylene group. Examples of the oxyfluoroalkylene group include groups represented by the following formula (F2): -(OR ｆ１２ ) ｍ２ -*...(F2) In formula (F2), R ｆ１２ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, m2 is an integer of 1 to 200, and * is a bond to Z. ｆ１２ Specific examples and preferred embodiments of the R ｆ１１ Specific examples and preferred embodiments of m2 are the same as those of m1.

[0023] R ｆ１ In the above formula, examples of the fluoroalkyl chain that does not contain an etheric oxygen atom between carbon atoms include a group represented by the following formula (F3): -(O) ｍ３ -R ｆ１３ -* ... (F3) In formula (F3), R ｆ１３ is a linear or branched fluoroalkylene group having 1 to 10 carbon atoms, m3 is 0 or 1, and * is a bond to Z. R ｆ１３ Specific examples of R ｆ１１ In addition to the above, -CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ -, -CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ -, -CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ -, -CF ２ CF ２ CF２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ CF ２ - etc. ｆ１３ The preferred carbon number of R is 1 to 6, and the more preferred structure is R ｆ１１ and a perfluoroalkylene group is preferred.

[0024] (ii) Next, in formula (1), n ​​is 2, that is, when one structural unit (1) contains two Zs, R ｆ１ We will explain about R ｆ１ Examples of the linear or branched fluoroalkyl chain which may contain an etheric oxygen atom in the formula (F1) include groups represented by the following formula (F4): -(O) ｍ４ -R ｆ１４ - (OR ｆ１４ ) ｍ５ -OR ｆ１５ (L １ - *) ２ ...(F4) In formula (F4), R ｆ１４ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, and R ｆ１５ is a linear or branched fluoroalkyl chain having 1 to 6 carbon atoms, and L １ are each independently a linear or branched fluoroalkylene group which may contain an etheric oxygen atom, m4 is 0 or 1, m5 is an integer of 0 to 200, and * is a bond to Z. ｆ１４ Specific examples and preferred embodiments of the R ｆ１１ It is the same as R ｆ１５ Specific examples of R ｆ１１ Specific examples thereof include trivalent groups obtained by removing one arbitrary hydrogen atom or fluorine atom from the above. m5 may be 0 to 200, and is preferably 0 to 150, more preferably 0 to 120, from the viewpoint of superior cleaning properties.

[0025] L １ is exemplified by a group represented by the following formula (L1): -(O) ｐ１ -L ｆ１ - (OLｆ２ ) ｐ２ -*...(L1) In formula (L1), L ｆ１ and L ｆ２ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, p1 is 0 or 1, p2 is an integer of 0 to 200, and * is a bond to Z. ｆ１ and L ｆ２ Specific examples and preferred embodiments of the R ｆ１１ and a perfluoroalkylene group is preferred. However, when p1 is 0, R ｆ１５ L １ or R ｆ１５ L １ ２ The number of carbon atoms therein is preferably 1 to 10, more preferably 1 to 6. p2 may be 0 to 200, and is preferably 0 to 100, more preferably 0 to 50, from the viewpoint of superior cleanability.

[0026] R ｆ１ In the above formula, the fluoroalkyl chain not containing an etheric oxygen atom between carbon atoms includes a group represented by the following formula (F5): -(O) ｍ６ -R ｆ１６ -*...(F5) In formula (F5), R ｆ１６ is a linear or branched trivalent fluoroalkyl chain having 1 to 10 carbon atoms, m3 is 0 or 1, and * is a bond to Z. R ｆ１６ Specific examples of R ｆ１３ Specific examples thereof include trivalent groups obtained by removing any one hydrogen atom or fluorine atom from the above.

[0027] ・Embodiment (II) R ２ and R ｆ１ A form in which the two are connected. １ R is a hydrogen atom, a fluorine atom or a chlorine atom, and from the viewpoint of cleaning properties, a fluorine atom or a chlorine atom is preferred, and a fluorine atom is more preferred. ３ represents a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group, and from the viewpoint of cleaning properties, a fluorine atom, a chlorine atom, or a fluoromethyl group is preferred, a fluorine atom or a fluoromethyl group is more preferred, and a fluorine atom is even more preferred.

[0028] R ２ and R ｆ１ An example of a linear or branched fluoroalkyl chain which may contain an etheric oxygen atom between carbon atoms and is formed by linking *-(O) ​​is a group represented by the following formula (F6): ｍ７ -R ｆ１７ - (OR ｆ１７ ) ｍ８ -(O) ｍ９ -**...(F6) In formula (F6), R ｆ１７ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, m7 is 0 or 1, m8 is an integer of 0 to 50, m9 is 0 or 1, * is CR １ is the bond on the side, and ** is CR ３ It is the connecting hand on the side.

[0029] R ｆ１７ Specific examples and preferred embodiments of the R ｆ１１ is the same as, except that R ｆ１７ At least one of the R ｆ１７ is the R ｆ１１ Specific examples of R include residues obtained by removing one or two arbitrary hydrogen atoms or fluorine atoms from R. ｆ１７ Among these, m8 is preferably a perfluoroalkylene group. m8 is an integer of 0 to 50, preferably 0 to 12, and more preferably 0 to 6.

[0030] Embodiment (III) R ３ and R ｆ１ A form in which the two are connected. １ and R ２ are each independently a hydrogen atom, a fluorine atom or a chlorine atom, and from the viewpoint of cleaning properties, a fluorine atom or a chlorine atom is preferred, and a fluorine atom is more preferred.

[0031] R ３ and R ｆ１ The linear or branched fluoroalkyl chain formed by linking *-(O) ​​and may contain an etheric oxygen atom between carbon atoms includes, for example, a group represented by the following formula (F7): ｍ１０ -R ｆ１８- (OR ｆ１８ ) ｍ１１ -(O) ｍ１２ -**...(F7) In formula (F7), R ｆ１８ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, m10 is 0 or 1, m11 is an integer of 0 to 50, m12 is 0 or 1, * is CR １ is the bond on the side, and ** is CR ３ It is the connecting hand on the side.

[0032] R ｆ１８ Specific examples and preferred embodiments of the R ｆ１１ is the same as, except that R ｆ１８ At least one of the R ｆ１８ is the R ｆ１１ Specific examples of R include residues obtained by removing one or two arbitrary hydrogen atoms or fluorine atoms from R. ｆ１８ Among these, m11 is preferably a perfluoroalkylene group. m11 is an integer of 0 to 50, preferably 0 to 12, and more preferably 0 to 6.

[0033] Z is -SO ３ H, -SO ３ Z １ , -CO ２ H, -CO ２ Z １ , -PO ３ H, -PO ３ Z １ or OH, and Z １ is a cation. １ Specific examples of Z include alkali metal ions such as sodium ions and potassium ions, and ammonium ions obtained by neutralization with ammonia or ethanolamine from the viewpoint of superior cleaning properties, and ammonium ions obtained by neutralization with ammonia or ethanolamine are preferred. Furthermore, Z is preferably -SO ３ H, -SO ３ Z １ , -CO ２ H or OH is preferred.

[0034] When the fluoropolymer has two or more structural units (1), the respective symbols may be the same or different. From the viewpoint of superior cleaning properties, the unit represented by formula (1) is preferably R １ , R ２ and R ３ In addition, in terms of superior cleaning properties, R ｆ１ The fluoroalkylene chain or oxyfluoroalkylene chain in the formula (I) is preferably a perfluoroalkylene chain or an oxyperfluoroalkylene chain.

[0035] Among the units represented by formula (1), specific examples of (i) in embodiment (I) include the following: where n is an integer of 1 to 200, and the acidic group may be in the form of a salt. -CF ２ -CF{OCF ２ CF (CF ３ ) OCF ２ CF ２ COOH}- -CF ２ -CF[CF ２ O{CF(CF ３ )CF ２ O} ｎ CF (CF ３ )COOH]--CF ２ -CF (OCF ２ CF ２ CF ２ OCF ２ CF ２ COOH)- -CF ２ -CF (OCF ２ CF ２ OCF ２ CF ２ COOH)- -CF ２ -CF (OCF ２ CF ２ COOH)- -CF ２ -CF (OCF ２ CF ２ CF ２ COOH)- -CF ２ -CF (OCF ２ CF ２ CF ２ CF ２ CF ２ COOH)- -CF ２-CF{OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ H}- -CF ２ -CF (OCF ２ CF ２ SO ３ H) - -CF ２ -CF (OCF ２ CF ２ CF ２ SO ３ H) - -CF ２ -CF (OCF ２ CF ２ CF ２ CF ２ SO ３ H) - -CF ２ -CF (OCF ２ CF ２ OCF ２ CF ２ SO ３ H) - -CF ２ -CF{OCF ２ CF (CF ３ ) OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ H}- -CF ２ -CF (CF ２ CF ２ SO ３ H) - -CF ２ -CF (CF ２ CF ２ CF ２ CF ２ SO ３ H) - -CF ２ -CF (CF ２ OCF ２ CF ２ SO ３ H)-

[0036] Among the units represented by formula (1), specific examples of (ii) in embodiment (I) include the following.

[0037] Among the units represented by formula (1), specific examples of embodiment (II) include the following.

[0038] Among the units represented by formula (1), specific examples of embodiment (III) include the following.

[0039] In terms of superior cleanability and ease of polymer synthesis, the structural unit (1) preferably has (i) of embodiment (I), and a unit represented by the following formula (1A) is preferred: -[CR １ R ２ -CR ３ (R ｆ１ -Z)]-...(1A) In formula (1A), R １ and R ２ are each independently a hydrogen atom, a fluorine atom or a chlorine atom, ３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group, and R ｆ１ is a linear or branched fluoroalkylene group which may contain an etheric oxygen atom, and R ｆ１ When Z is a fluoroalkylene group containing no etheric oxygen atom, it has 1 to 10 carbon atoms. ３ H, -SO ３ Z １ , -CO ２ H, -CO ２ Z １ , -PO(OH) ２ , -PO ３ (OZ １ ) ２ or OH, and Z １ Each symbol in formula (1A) is the same as that in formula (1), and preferred embodiments are also as described above, so explanations thereof will be omitted here.

[0040] (Other Structural Units) The present fluoropolymer may be a polymer consisting only of units represented by formula (1), or may be a copolymer containing other structural units. Examples of other structural units include the following structural units (11) to (13). Structural unit (11): A structural unit having an acidic group and a fluorine atom and having a structure different from that of formula (1). Structural unit (12): A structural unit having a fluorine atom and no acidic group. Structural unit (13): A structural unit not having a fluorine atom.

[0041] Examples of the structural unit (11) include units derived from a monomer in which at least one hydrogen atom in a known monomer having an acidic group, such as (meth)acrylic acid, has been substituted with a fluorine atom.

[0042] An example of the structural unit (12) is a unit represented by the following formula (12): —CR ２１ R ２２ -CR ２３ R ２４ -...(12) In formula (12), R ２１ and R ２２ are each independently a hydrogen atom, a fluorine atom or a chlorine atom, ２３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group, and R ２４ represents a hydrogen atom, a fluorine atom, a chlorine atom, a linear or branched fluoroalkyl group which may contain an etheric oxygen atom between carbon atoms, or a linear or branched oxyfluoroalkyl group which may contain an etheric oxygen atom between carbon atoms, and R ２４ When the etheric oxygen atom is not present, the number of carbon atoms is 1 to 10.

[0043] R ２１ and R ２２ R each independently represents a hydrogen atom, a fluorine atom, or a chlorine atom, and from the viewpoint of cleaning properties, a fluorine atom or a chlorine atom is preferred, and a fluorine atom is more preferred. ２３represents a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group, and from the viewpoint of cleaning properties, a fluorine atom, a chlorine atom, or a fluoromethyl group is preferred, a fluorine atom or a fluoromethyl group is more preferred, and a fluorine atom is even more preferred.

[0044] R ２４ Examples of the linear or branched fluoroalkyl group which may contain an etheric oxygen atom between carbon atoms in the formula (21) include groups represented by the following formula (21): ｆ２１ - (OR ｆ２１ ) ｍ２１ -R ２５ ...(21) In formula (21), R ｆ２１ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, m21 is an integer of 1 to 200, and R ２５ is a hydrogen atom or a fluorine atom.

[0045] R ｆ２１ Specific examples and preferred embodiments of the R ｆ１１ Specific examples and preferred embodiments of m21 are the same as those of m1. ２５ is preferably a fluorine atom.

[0046] R ２４ As the linear or branched oxyfluoroalkyl group which may contain an etheric oxygen atom between carbon atoms in the formula (22), a group represented by the following formula (22) can be mentioned: -(OR ｆ２２ ) ｍ２２ -R ２６ ...(22) In formula (22), R ｆ２２ are each independently a linear or branched fluoroalkylene group having 1 to 6 carbon atoms, m22 is an integer of 1 to 200, and R ２６ is a hydrogen atom or a fluorine atom. ｆ２２ Specific examples and preferred embodiments of the R ｆ１１ Specific examples and preferred embodiments of m22 are the same as those of m1.

[0047] R ２４Examples of the fluoroalkyl or oxyfluoroalkyl group not containing an etheric oxygen atom between carbon atoms in the formula (23) include groups represented by the following formula (23): -(O) ｍ２３ -R ｆ２３ -R ２７ ...(23) In formula (23), R ｆ２３ is a linear or branched fluoroalkyl group having 1 to 10 carbon atoms, m23 is 0 or 1, and R ２７ is a hydrogen atom or a fluorine atom. ｆ２３ Specific examples and preferred embodiments of the R ｆ１１ and R ｆ１３ is the same as:

[0048] When the fluoropolymer has two or more structural units (12), the symbols may be the same or different. From the viewpoint of cleaning properties, the unit represented by formula (12) is preferably R ２１ , R ２２ In terms of superior cleaning properties, R ２３ is preferably a fluorine atom or a fluoromethyl group, and more preferably a fluorine atom. ２４ is preferably a fluorine atom, a linear or branched perfluoroalkyl group which may contain an etheric oxygen atom between the carbon atoms, or a linear or branched oxyperfluoroalkyl group which may contain an etheric oxygen atom between the carbon atoms, and more preferably a fluorine atom. Specific examples of the structural unit (12) include the following: -CF ２ -CF ２ -CF ２ -CF (OCF ２ CF ２ CF ３ ) - -CF ２ -CF{OCF ２ CF (CF ３ ) OCF ２ CF ３ - -CF ２ -CF{OCF ２ CF (CF ３ ) OCF ２ CF ２ CF ３ - -CF２ -CF[CF ２ O{CF(CF ３ )CF ２ O} ｎ CF ２ (CF ３ ) ]- -CF ２ -CF (OCF ２ CF ２ CF ２ OCF ２ CF ３ ) - -CF ２ -CF (OCF ２ CF ２ OCF ２ CF ３ ) - -CF ２ -CF (OCF ２ CF ２ CF ２ CF ２ CF ３ ) - -CF ２ -CF (OCF ２ CF ３ ) - -CF ２ -CF (OCF ３ )—where n is an integer from 1 to 200.

[0049] Examples of the structural unit (13) include structural units derived from known monomers that do not contain fluorine atoms. Specific examples of such monomers include vinyl monomers such as ethylene, vinyl chloride, vinylidene chloride, styrene, methylstyrene, vinyltoluene, and p-t-butylstyrene; (meth)acrylate monomers such as methyl(meth)acrylate, ethyl(meth)acrylate, and n-propyl(meth)acrylate; acrylamide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-diethyl(meth)acrylamide; and (meth)acrylic acid.

[0050] (Constituent Ratio) The fluoropolymer used in the present cleaning solution preferably contains the structural unit (1), and more preferably contains the structural unit (1A). Furthermore, from the viewpoint of superior cleaning properties and polymer handleability, it is preferable that the fluoropolymer further contains the structural unit (12). When the structural unit (12) is contained, the molar ratio of the structural unit (1) to the structural unit (12) is preferably 5:95 to 60:40, more preferably 10:90 to 50:50, and even more preferably 15:85 to 40:60. From the viewpoint of superior cleaning properties, the structural unit (13) is preferably 10 mol % or less, more preferably 5 mol % or less, and even more preferably 1 mol % or less, of all the structural units constituting the fluoropolymer, and it is particularly preferable that the structural unit (13) is not contained.

[0051] The arrangement of each structural unit is not particularly limited, and the copolymer may be a random copolymer or a block copolymer, with random copolymers being preferred from the viewpoint of excellent detergency.

[0052] The proportion of the fluoropolymer in the cleaning solution is preferably 0.001 to 30 mass %, more preferably 0.005 to 20 mass %, and particularly preferably 0.01 to 10 mass %, based on the total amount of the cleaning solution. A cleaning solution containing a high concentration of the fluoropolymer may be prepared and then diluted appropriately before use.

[0053] (Synthesis of Fluorine Polymer) The synthesis method of the fluoropolymer is not particularly limited. For example, when synthesizing a random copolymer of the structural unit (1) and the structural unit (12), the following monomer (1a) corresponding to the structural unit (1) and the following monomer (12a) corresponding to the structural unit (12) are mixed, and an initiator is further added, followed by polymerization by a known polymerization method such as solution polymerization, bulk polymerization, or various radical polymerizations. Solution polymerization is preferred from the viewpoint of ease of adjusting the number average molecular weight of the polymer. In the case of a block polymer, for example, the block of the structural unit (1) may be synthesized first, and then the monomer (12a) may be polymerized to the block of the structural unit (1), or the order of synthesis in this production method may be reversed. Alternatively, the block of the structural unit (1) and the block of the structural unit (12) may be synthesized separately, and then the block of the structural unit (1) and the block of the structural unit (12) may be coupled. CR １R ２ =CR ３ {R ｆ１ -(Z) ｎ} ...(1a) CR ２１ R ２２ =CR ２３ R ２４ ... (12a) Note that the symbols in the formula are as described above.

[0054] <Water> The cleaning solution contains water as a medium for dispersing or dissolving the fluoropolymer. The type of water is not particularly limited, but it is preferable to use pure water, ultrapure water, ion-exchanged water, etc., taking into consideration the effects on other components, prevention of impurity contamination, and effects on pH, etc.

[0055] <Optional Components> The present cleaning solution may further contain other components, such as a reducing compound, a complexing agent, a heterocyclic aromatic compound, an acidic compound, an antiseptic, a rust inhibitor, a surfactant, a basic compound, and a water-soluble organic solvent.

[0056] (Reducing Compound) The cleaning solution may contain a reducing compound. The reducing compound may be, for example, cerium (CeO ４ ) with water-soluble Ce ３＋ By reducing the abrasive grain components to the above-mentioned compound, they can be easily removed from the surface to be cleaned, improving the cleaning effect. The reducing compound can be appropriately selected from compounds that have a reducing effect on the abrasive grain components. Among them, preferred reducing compounds are gallic acid or its salts, gallic acid esters, pyrogallol, catechol, resorcinol, thiosulfuric acid or its salts, dithionic acid or its salts, ascorbic acid, uric acid, diphosphorous acid or its salts, oxalic acid or its salts, hydrogen peroxide, and hydroquinone.

[0057] When a reducing compound is used, the content of the reducing compound in the cleaning solution is preferably 0.001 to 30% by mass, more preferably 0.005 to 20% by mass, and even more preferably 0.01 to 10% by mass, based on the total amount of the cleaning solution.

[0058] (Complexing Agent) The present cleaning solution may contain a complexing agent. The complexing agent can be appropriately selected from among those that form complexes with the metal components in the abrasive grains and the metal components in the residues derived from the substrate generated by polishing. In the present cleaning solution, in order to improve the cleaning effect, the complexing agent is preferably an organic compound having a molecular weight of 1,000 g / mol or less and having two or more substituents selected from a carboxyl group, an amino group, a phosphoryl group, a sulfonic acid group, and a hydroxyl group in the molecule. Complexing agents include tetramethylethylenediamine (TMEDA), ethylenediaminetetraacetic acid (EDTA), N-hydroxyethylethylenediaminetriacetic acid (NHEDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DPTA), ethanol diglycinate, citric acid, malic acid, gluconic acid, oxalic acid, phosphoric acid, tartaric acid, malonic acid, succinic acid, dimercaptosuccinic acid, glutaric acid, maleic acid, phthalic acid, fumaric acid, methyldiphosphonic acid, aminotrismethylenephosphonic acid, ethylidene-diphosphonic acid, 1-methyl-2-methyl-1-propanol ... 1,2-propanediaminepentamethylenephosphonic acid or ammonium salts thereof, etc. When a complexing agent is used, the content of the complexing agent in the cleaning solution is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and still more preferably 0.1 to 10% by mass, based on the total amount of the cleaning solution.

[0059] (Heterocyclic aromatic compound) The present cleaning solution may contain a heterocyclic aromatic compound. A cleaning solution containing a heterocyclic aromatic compound is less susceptible to quality degradation due to microorganisms and the like, and provides a more excellent cleaning effect. Examples of heterocyclic aromatic compounds include imidazole-based compounds, pyrazole-based compounds, thiazole-based compounds, and triazole-based compounds. Examples of imidazole-based compounds include imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole. Examples of pyrazole-based compounds include pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole. Examples of thiazole compounds include benzisothiazoline, isothiazolin, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-(thiocyanomethylthio)benzthiazole, 2-mercaptobenzthiazole, and 3-allyloxy-1,2-benzisothiazole-1,1-oxide. Examples of triazole compounds include 1H-benzotriazole, 4-methyl-1H-benzotriazole, and 5-methyl-1H-benzotriazole. When a heterocyclic aromatic compound is used, the content of the heterocyclic aromatic compound in the cleaning solution is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and particularly preferably 0.1 to 10% by mass, based on the total amount of the cleaning solution.

[0060] (Surfactant) The cleaning solution may contain a surfactant. The surfactant may be ionic or nonionic. Examples of the surfactant include salts containing suitable hydrophobic properties, such as alkyl carboxylates, alkyl polyacrylates, alkyl sulfates, alkyl phosphates, alkyl bicarboxylates, alkyl bisulfates, alkyl biphosphates, substituted aryl carboxylates, substituted aryl sulfates, substituted aryl phosphates, substituted aryl bicarboxylates, substituted aryl bisulfates, and substituted aryl biphosphates; long-chain alcohols, ethoxylated alcohols, ethoxylated acetylenic diol surfactants, polyethylene glycol alkyl ethers, propylene glycol alkyl ethers, glucoside alkyl ethers, polyethylene glycol octylphenyl ethers, polyethylene glycol alkylphenyl ethers, glycerol alkyl esters, polyoxyethylene glycol sorbitone alkyl esters, sorbitone alkyl esters, cocamide diethanolamine dodecyl dimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated tallow amine, and fluorosurfactants.

[0061] (Acidic Compound) The present cleaning solution may contain an acidic compound other than the fluoropolymer having an acidic group. The acidic compound is used for the purpose of adjusting the pH, etc. As the acidic compound, inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and condensed phosphoric acid are preferred.

[0062] (Basic Compound) The present cleaning solution may contain a basic compound. The basic compound is used for purposes such as pH adjustment. Examples of basic compounds include monoethanolamine (MEA), diethanolamine, triethanolamine (TMA), morpholine, isopropylamine, hydroxyamine, diisopropanolamine, diglycolamine, triethylamine, N-methylmorpholine, methylethanolamine, N-aminopropylmorpholine, and 3-amino-propanol, tetramethylammonium hydroxide (TMAH), ammonium hydroxide, tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), tributylmethylammonium hydroxide (TBMAH), benzyltrimethylammonium hydroxide (BTMAH), choline, choline hydroxide, ethyltrimethylammonium hydroxide, tris(2-hydroxyethyl)methylammonium hydroxide, diethyldimethylammonium hydroxide, and combinations thereof. Among these, ammonium hydroxide, choline, monoethanolamine, hydroxyamine, or triethanolamine is preferred as the basic compound.

[0063] The cleaning performance of the present cleaning solution is further improved by adjusting the pH to within the range of 1 to 12. When the present cleaning solution is used in an acidic environment, the pH is preferably 7 or less, more preferably 1 to 5, in order to further improve the cleaning performance. When the present cleaning solution is used in a basic environment, the pH is preferably 7 or more, more preferably 8 to 12, in order to further improve the cleaning performance.

[0064] (Water-soluble organic solvent) The cleaning solution may contain a water-soluble organic solvent. Examples of water-soluble organic solvents include propylene glycol (PG), glycol ether, and aprotic solvents. Examples of aprotic solvents include N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAC), sulfolane, and dimethylformamide (DMF). The water-soluble organic solvent may be a mixed solvent of two or more types.

[0065] <Uses of the Cleaning Solution> The cleaning solution is suitable for removing abrasive particles from a surface to be cleaned, and can also effectively remove organic components such as polymers contained in abrasives. Examples of surfaces to be cleaned include exposed surfaces (surfaces) of semiconductor substrates, which may contain silicon dioxide and / or silicon nitride. The surface to be cleaned may be an exposed surface that has been polished using an abrasive containing abrasive particles. Examples of such abrasive particles include silica particles, alumina particles, zirconia particles, titania particles, germania particles, and cerium compound-containing particles. The cleaning solution is particularly suitable for cerium compound-containing particles such as ceria particles and cerium hydroxide particles. The cleaning solution can also be used with fine abrasive particles, and exhibits excellent cleaning effects even with abrasive particles having an average particle diameter of 300 nm or less. The cleaning solution is particularly effective for semiconductor substrates that have undergone CMP processing using an abrasive containing cerium compound-containing particles as abrasive particles, and which include exposed surfaces on which oxide films, nitride films, and the like are exposed. Cerium particles adsorbed or bonded to the oxide film or the like remain on the exposed surface, but this cleaning solution can effectively remove these particles.

[0066] [Cleaning Method] The cleaning method of the present disclosure includes cleaning a surface to be cleaned using the cleaning liquid. Specific examples include scrub cleaning, in which the cleaning liquid is supplied to a surface to be cleaned, such as a semiconductor substrate, while a cleaning member such as a pad or brush is brought into physical contact with the surface to be cleaned to remove abrasive grains, immersion cleaning, in which an object to be cleaned including the surface to be cleaned is immersed in the cleaning liquid, spin-drop cleaning, in which the cleaning liquid is dropped onto the rotating object, and spray cleaning, in which the cleaning liquid is sprayed. In immersion cleaning, the cleaning liquid may be subjected to ultrasonic treatment. The cleaning process may be performed once or twice or more times.

[0067] The temperature of the cleaning solution may be adjusted appropriately taking into consideration the heat resistance of the object to be cleaned, etc. The temperature of the cleaning solution may be adjusted appropriately within the range of, for example, 10 to 60° C., and preferably 15 to 50° C. The cleaning time may be adjusted appropriately within the range of 10 seconds to 5 minutes, and preferably 20 seconds to 3 minutes.

[0068] In this cleaning method, after cleaning with the cleaning solution, further cleaning with water or the like may be carried out as necessary, and drying may also be carried out as necessary.

[0069] The present disclosure further provides a semiconductor element obtained by the above cleaning method, which has a clean surface with few abrasive grains or polishing residues.

[0070] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, room temperature is 20 to 25°C. Examples 1 to 15 are examples, and Examples 16 to 19 are comparative examples.

[0071] [Evaluation Items and Evaluation Methods] The evaluation items and evaluation methods are as follows. <pH> The pH of the cleaning solution was measured using a commercially available pH meter while stirring with a magnetic stirrer. The pH meter used was a pH meter "F-2000PI-S" manufactured by Horiba, Ltd., and a Tou pH electrode "9615S-10D."

[0072] <Removal Performance of Cerium Oxide and Organic Components> (Preparation of Polished Substrate) A commercially available slurry-like abrasive (polishing slurry) containing cerium oxide particles with an average particle size of 300 nm or less, organic components such as polymers, surfactants, and water was prepared. One surface of a quartz glass plate was polished for 30 seconds using a commercially available CMP device and the abrasive. A SpeedFam "FAM12B" CMP device was used. A hard urethane pad was used as the polishing pad. Polishing was performed for 5 minutes under a polishing pressure of 14 kPa, with a platen rotation speed of 40 rpm and a flow rate of 30 cc per minute of chemical solution. Polishing was performed under the above conditions, rinsed several times with pure water, and then submerged and stored to obtain a ceria-contaminated substrate.

[0073] (Post-cleaning of polished substrate) Obtained ceria-contaminated SiO ２ The substrate was subjected to PVA disk sponge cleaning (rotation speed 300 rpm, substrate conveyance speed 12.5 mm / s, cleaning process using 5 ml of cleaning solution was performed twice for each substrate). After rinsing with pure water several times, the substrate was dried to obtain a cleaned substrate. The polished substrate that had undergone the above treatment is referred to as the "polished substrate after post-cleaning."

[0074] (Evaluation of the amount of remaining cerium oxide after post-cleaning and cerium oxide removal performance) After post-cleaning, the polished substrate was counted for the number of ceria contaminant particles remaining on the substrate using a particle inspection device (LODAS manufactured by LAZIN). The cerium oxide removal performance was evaluated according to the following criteria: A (Good): Particle count after post-cleaning was 500 or less. B (Fair): Particle count after post-cleaning was 1,000 or less. C (Poor): Particle count after post-cleaning was more than 1,000.

[0075] [Materials] The materials used in each example are as follows: <Water-soluble polymer> Fluoropolymer 1: tetrafluoroethylene (-CF ２ CF ２ -) structure and SO ３ H group fluoroalkylene (-CF ２ CF (OCF ２ CF (CF ３ ) OCF ２ CF ２ SO ３ H)-) structures in a molar ratio of 73:27. The concentration of acidic groups per unit mass was 1.40 mmol / g. Fluoropolymer 2: A water-soluble binary fluorocopolymer containing the above monomer unit structures in a molar ratio of 78:22. The concentration of acidic groups per unit mass was 1.25 mmol / g. Fluoropolymer 3: A water-soluble binary polymer containing the above monomer unit structures in a molar ratio of 82:18. The concentration of acidic groups per unit mass was 1.10 mmol / g. Fluoropolymer 4: A water-soluble binary copolymer containing CO ２ H group fluoroalkylene (-CF ２ CF (OCF ２ CF ２ CF ２ CO ２ Water-soluble fluorine homopolymer formed only of H)-) structure. The concentration of acidic groups per unit mass is 3.42 mmol / g. Fluorine polymer 5: containing CO ２ H group fluoroalkylene (-CF ２ CF (OCF ２ CF (CF ３ ) OCF ２ CF ２ CO ２A water-soluble fluorine homopolymer formed only of H)-) structures. The concentration of acidic groups per unit mass is 2.45 mmol / g. Polyacrylic acid (water-soluble polymer for comparison): purity 100% by mass, reagent.

[0076] <pH adjuster> (inorganic acid compound) 0.1N HNO ３ aq.: 0.1N nitric acid aqueous solution, reagent; 0.1N polyphosphoric acid aq.: 0.1N condensed phosphoric acid (P(O)(OH)O) ｎ , Reagent. (Basic compound) 0.1N triethanolamine aq.: 0.1N triethanolamine aqueous solution, reagent.

[0077] <Reducing compound> 30% H ２ O ２ aq.: 30% by mass hydrogen peroxide solution. Gallic acid: 98% by mass purity, reagent. Pyrogallol: 100% by mass purity, reagent. Ascorbic acid: 100% by mass purity, reagent. Hydroquinone: 100% by mass purity, reagent.

[0078] <Complexing agent> Citric acid: 100% purity by mass, reagent. HEDP: 1-hydroxyethylidene-1,1-diphosphonic acid, 60% purity by mass, manufactured by Chelest Co., Ltd., "Chelest PH-210".

[0079] <Heterocyclic aromatic compounds> (thiazole compounds) KB-838: 0.075% aqueous solution, a diluted solution obtained by diluting "KB-838" manufactured by IK Chemicals Co., Ltd. 100 times with water.

[0080] [Example 1] A cleaning solution was prepared by adding 0.2 g of fluoropolymer 1 and 0.3 g of 0.075% KB-838 to 99.5 g of ultrapure water at room temperature and stirring. The total concentration of the pH adjuster, reducing compound, organic acid compound, and heterocyclic aromatic compound was determined as the amount of active ingredients (total content of active ingredients, total concentration of active ingredients). The total concentration of active ingredients was 0.20 mass%. The pH of the cleaning solution was 3.00. The formulation and evaluation results are shown in Table 1.

[0081] [Examples 2 to 19] Cleaning solutions were prepared in the same manner as in Example 1, except that the blending compositions were changed to those shown in Table 1. The blending compositions and evaluation results are shown in Table 1.

[0082]

[0083] [Summary of Results] The cleaning solutions of Examples 1 to 15, which contain a fluoropolymer having acidic groups, were shown to have excellent ceria particle removal performance. Such cleaning effects were not observed in Example 18, which used polyacrylic acid instead of a fluoropolymer. Furthermore, the cleaning solution of Example 16, in which nitric acid was used to lower the pH, did not provide sufficient cleaning effects. It was thus discovered that a cleaning solution with high cleaning performance can be obtained by using a fluoropolymer having acidic groups.

[0084] The cleaning liquid of the present disclosure can be used, for example, as a cleaning liquid for abrasives used in CMP, and contributes to improving the production efficiency of semiconductor elements.

[0085] This application claims priority based on Japanese Patent Application No. 2023-97860, filed on June 14, 2023, the disclosure of which is incorporated herein in its entirety.

Claims

1. A cleaning solution for removing abrasive grains, comprising a fluoropolymer having acidic groups and water.

2. The cleaning solution according to claim 1, wherein the fluoropolymer has a unit represented by the following formula (1): -[CR １ R ２ -CR ３ {R ｆ１ - (Z) ｎ }]-...(1) In formula (1), R １ and R ２ are each independently a hydrogen atom, a fluorine atom, or a chlorine atom; R ３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group; R ｆ１ is a linear or branched fluoroalkyl chain which may contain an etheric oxygen atom, or R ２ and R ｆ１ are linked together to form a linear or branched fluoroalkyl chain which may contain an ether oxygen atom between carbon atoms, or R ３ and R ｆ１ is a linear or branched fluoroalkyl chain which may contain an ether oxygen atom between carbon atoms, and Z is -SO ３ H, -SO ３ Z １ , -CO ２ H, -CO ２ Z １ , -PO(OH) ２ , -PO ３ (O.Z. １ ) ２ or OH; Z １ is a cation; and n is 1 or 2.

3. The cleaning solution according to claim 1, wherein the fluoropolymer has a unit represented by the following formula (1A): -[CR １ R ２ -CR ３ (R ｆ１ -Z)]-...(1A) In formula (1A), R １ and R ２ each independently represents a hydrogen atom, a fluorine atom or a chlorine atom; R ３ is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a fluoromethyl group; R ｆ１ is a linear or branched fluoroalkylene group which may contain an etheric oxygen atom, R ｆ１ is a fluoroalkylene group containing no etheric oxygen atom, the number of carbon atoms is 1 to 10, and Z is -SO ３ H, -SO ３ Z １ , -CO ２ H, -CO ２ Z １ , -PO(OH) ２ , -PO ３ (O.Z. １ ) ２ or OH; Z １ is a cation.

4. R １ , R ２ and R ３ The cleaning solution according to claim 3 , wherein each of 5. The cleaning solution according to claim 1, wherein the concentration of acidic groups contained in 1 g of the fluoropolymer is 0.3 to 4.0 mmol / g.

6. The cleaning solution of claim 1, further comprising a reducing compound.

7. The cleaning solution according to claim 6, wherein the reducing compound comprises at least one selected from the group consisting of gallic acid, gallic acid esters, pyrogallol, catechol, resorcinol, ascorbic acid, uric acid, diphosphorous acid, dithioic acid, thiosulfuric acid, oxalic acid, hydrogen peroxide, and hydroquinone.

8. The cleaning solution according to claim 1, further comprising at least one complexing agent which is an organic compound having two or more substituents selected from a carboxyl group, an amino group, a phosphoryl group, a sulfonic acid group and a hydroxyl group in the molecule and a molecular weight of 1,000 g / mol or less.

9. The cleaning solution according to claim 1, further comprising at least one heterocyclic aromatic compound selected from the group consisting of imidazole-based compounds, pyrazole-based compounds, thiazole-based compounds, and triazole-based compounds.

10. The cleaning solution according to claim 1, comprising 0.001% to 30% by mass of the fluoropolymer.

11. The cleaning solution according to claim 6, comprising 0.001% by mass to 30% by mass of the reducing compound.

12. The cleaning solution according to claim 1, having a pH of 1 to 5.

13. The cleaning solution according to claim 12, further comprising at least one selected from the group consisting of nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and condensed phosphoric acid.

14. The cleaning solution according to claim 1, having a pH of 8 to 12.

15. The cleaning solution of claim 14, further comprising at least one member selected from the group consisting of ammonium hydroxide, choline, hydroxylamine, monoethanolamine, diethanolamine, and triethanolamine.

16. The cleaning solution of claim 1, wherein the abrasive particles comprise cerium compound-containing particles.

17. The cleaning solution according to claim 1, which is used for cleaning an object having abrasive components and organic components attached to the exposed surface of a semiconductor substrate.

18. The cleaning solution of claim 17, wherein the exposed surface comprises at least one selected from the group consisting of silicon dioxide and silicon nitride.

19. The cleaning solution according to claim 1, which is used for cleaning an object whose surface has been polished using an abrasive containing abrasive grains.

20. The cleaning solution according to claim 1, wherein the average particle size of the abrasive grains is 300 nm or less.

21. A cleaning method comprising cleaning a surface to be cleaned with a cleaning liquid according to any one of claims 1 to 20.

22. A method for manufacturing a semiconductor device, comprising cleaning an exposed surface of a semiconductor substrate with a cleaning solution according to any one of claims 1 to 20.