JP2017114986A - Polishing liquid and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing liquid capable of polishing a cobalt-containing portion at a high CMP rate and a low etching rate.SOLUTION: The polishing liquid for polishing at least a cobalt-containing portion of a substrate provided with a surface having the cobalt-containing portion contains: (A) glycine; (B) at least one selected from the group consisting of amino acids and amino acid derivatives (excluding the component (A)); (C) at least one selected from the group consisting of carboxylic acids and carboxylic acid derivatives (excluding the component (A) and the component (B)); and (D) a compound having a benzotriazole skeleton.SELECTED DRAWING: None

Description

  The present invention relates to a polishing liquid and a polishing method.

  2. Description of the Related Art In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor large-scale integrated circuits (Large-Scale Integration; hereinafter referred to as “LSI”). One of them is a chemical mechanical polishing (hereinafter referred to as “CMP”) method. The CMP method is a technique that is frequently used in planarization of an interlayer insulating material, formation of a metal plug, formation of a buried wiring, and the like in a semiconductor device manufacturing process, particularly in a multilayer wiring forming process.

  Currently, copper-based metals such as copper, copper alloys, copper oxides and copper alloy oxides are mainly used as wiring materials. Usually, a so-called damascene method is adopted for forming a buried wiring using a copper-based metal. In the damascene method, first, a copper-based metal is deposited on an insulating material in which a concave portion (for example, a groove portion) and a convex portion (for example, a raised portion) are previously formed on the surface, and the concave portion is filled with the copper-based metal. Next, the copper-based metal deposited on the convex portion (that is, the copper-based metal other than in the concave portion) is removed by CMP to form a buried wiring.

  The polishing liquid used for CMP of a copper-based metal contains abrasive grains, an oxidizing agent, a metal dissolving agent, a metal anticorrosive, and the like as necessary. Further, polishing liquids to which various substances are added as additives have been studied. With these polishing liquids, a relatively high CMP rate and a relatively low etching rate may be obtained for copper-based metals (see, for example, Patent Documents 1 and 2 below).

JP 2010-538457 A JP 2009-514219 A

  Incidentally, the trend of LSI is toward further higher integration and higher performance. Along with this, miniaturization is required for embedded wiring by the damascene method. However, there is a technical limit to the embedding of the copper-based metal in the recess, and an embedding failure may occur. Therefore, the burying property of the copper-based metal is improved by using a barrier film (cobalt, ruthenium, etc.) having a good burying property. However, for example, in a state-of-the-art semiconductor device manufacturing process that requires a 1 × nm node, the copper-based metal embeddability is approaching its limit even when a barrier film with good embeddability is used. Therefore, in recent years, there has been a movement to replace the wiring material from copper-based metal with cobalt having good embedding property.

  However, according to the knowledge of the present inventors, it has been found that it is difficult to polish cobalt at a high CMP rate by CMP using a conventional polishing liquid. Further, cobalt has a low standard oxidation-reduction potential and tends to be etched easily, and it has been found that it is difficult to polish cobalt without corrosion by CMP using a conventional polishing liquid. When cobalt is corroded, a defect is generated in the formed wiring pattern, which may cause malfunction of the device.

  In view of the above problems, an object of one embodiment of the present invention is to provide a polishing liquid capable of polishing a cobalt-containing portion at a high CMP rate and a low etching rate. Another object of the present invention is to provide a polishing method capable of polishing a cobalt-containing portion at a high CMP rate and a low etching rate.

  The present inventors have (A) glycine, (B) at least one selected from the group consisting of amino acids and amino acid derivatives, (C) at least one selected from the group consisting of carboxylic acids and carboxylic acid derivatives, and (D ) It has been found that a polishing liquid containing a compound having a benzotriazole skeleton can achieve a high CMP rate and a low etching rate with respect to a cobalt-containing part, and the present invention including various embodiments has been completed.

  One embodiment of the present invention is a polishing liquid for polishing at least the cobalt-containing portion of a substrate having a surface having a cobalt-containing portion, and is a group consisting of (A) glycine, (B) an amino acid, and an amino acid derivative. And at least one selected from the group consisting of (C) a carboxylic acid and a carboxylic acid derivative (provided that the component (A) and the component (B) are included). And (D) a compound having a benzotriazole skeleton.

  In the polishing liquid according to an embodiment of the present invention, the surface of the substrate may not have a copper-containing portion.

  The pH of the polishing liquid according to one embodiment of the present invention is 4.0 to 8.0.

  In the polishing liquid according to an embodiment of the present invention, the component (C) includes at least one selected from the group consisting of phthalic acid and phthalic acid derivatives.

  The polishing liquid according to one embodiment of the present invention further contains at least one selected from the group consisting of hydrogen peroxide, potassium periodate, and ozone.

  The polishing liquid according to one embodiment of the present invention further contains polishing abrasive grains.

  Other embodiment of this invention is related with the grinding | polishing method of grind | polishing at least the said cobalt containing part of the board | substrate provided with the surface which has a cobalt containing part using the said polishing liquid.

  In the polishing method according to another embodiment of the present invention, the surface of the substrate may not have a copper-containing portion.

  According to the polishing liquid according to an embodiment of the present invention, the cobalt-containing portion can be polished at a high CMP rate and a low etching rate. In addition, according to the polishing method according to another embodiment of the present invention, the cobalt-containing portion can be polished at a high CMP rate and a low etching rate.

It is a schematic cross section which shows an example of the grinding | polishing method which concerns on one Embodiment of this invention.

  Hereinafter, a polishing liquid and a polishing method according to embodiments of the present invention will be described in detail.

(Definition)
Terms used in this specification will be explained.
“Polishing substance A” and “polishing substance A” are defined as removing at least a portion of substance A by polishing.
“High CMP rate” is defined as a high rate at which the material A to be polished is removed by CMP (for example, a reduction in the thickness of the material A per hour).
“Low etching rate” is defined as a small rate at which the substance A to be polished dissolves in the polishing liquid (for example, a reduction in the thickness of the substance A per hour).

“Cobalt-containing part” means a part containing a cobalt atom, and “cobalt-containing part” includes, for example, a part containing cobalt, a cobalt alloy, a cobalt oxide, a cobalt alloy oxide, or the like. .
The “copper-containing part” means a part containing a copper atom, and the “copper-containing part” includes, for example, a part containing copper, a copper alloy, a copper oxide, a copper alloy oxide, or the like. .

  The numerical range indicated using “to” means a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. The materials exemplified below may be used alone or in combination of two or more unless otherwise specified. The content of each component in the polishing liquid means the total amount of the plurality of substances present in the polishing liquid unless there is a specific notice when there are a plurality of substances corresponding to each component in the polishing liquid.

<Polishing liquid>
The polishing liquid according to the present embodiment is a polishing liquid for polishing at least the cobalt-containing portion of a substrate having a surface having a cobalt-containing portion (a substrate having a cobalt-containing portion on the surface). The polishing liquid according to this embodiment is used, for example, in a semiconductor device manufacturing process.

  The polishing liquid according to this embodiment is at least one selected from the group consisting of (A) glycine (hereinafter sometimes referred to as “(A) component”) and (B) an amino acid and an amino acid derivative (provided that (A (Hereinafter, referred to as “component (B)”), and (C) at least one selected from the group consisting of carboxylic acids and carboxylic acid derivatives (provided that component (A) and component (B)) In the following, it contains “(C) component”) and (D) a compound having a benzotriazole skeleton (hereinafter sometimes referred to as “(D) component”). The polishing liquid according to this embodiment may further contain an optional component. As the component (A), the component (B), the component (C), the component (D), and the optional component, one type may be used alone, or two or more types may be used in combination.

((A) Glycine)
The polishing liquid according to this embodiment contains glycine. Glycine is considered to function as a solubilizer for the cobalt-containing part, but is not limited thereto. Glycine is a compound having both amino and carboxyl functional groups.

  The content of glycine is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass with respect to 100 parts by mass of the polishing liquid from the viewpoint that the cobalt-containing part is sufficiently dissolved. Part or more is more preferable, 0.05 part by weight or more is particularly preferable, and 0.1 part by weight or more is extremely preferable. Further, the content of glycine is preferably 50 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 10 parts by mass or less, more preferably 5 parts by mass with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily suppressing etching. Part or less is particularly preferable, and 3 parts by mass or less is extremely preferable.

  In one Embodiment, it is preferable that content of glycine is 0.1-3 mass parts with respect to 100 mass parts of polishing liquid. Thereby, a high CMP rate and a low etching rate can be achieved to a higher degree.

((B) amino acids and amino acid derivatives)
The polishing liquid according to the present embodiment contains at least one selected from the group consisting of amino acids and amino acid derivatives (excluding the component (A)). (B) Although it is thought that a component functions as a melt | dissolution adjuvant with respect to a cobalt containing part, it is not limited to this. Amino acid derivatives include amino acid esters, amino acid salts, peptides and the like. An amino acid is a compound having both an amino group and a carboxyl group.

  As the component (B), α-alanine, β-alanine (alias: 3-aminopropanoic acid), 2-aminobutyric acid, norvaline, valine, leucine, norleucine, isoleucine, alloisoleucine, phenylalanine, proline, sarcosine, ornithine, Lysine, serine, threonine, allothreonine, homoserine, tyrosine, 3,5-diiodo-tyrosine, β- (3,4-dihydroxyphenyl) -alanine, thyroxine, 4-hydroxy-proline, cysteine, methionine, ethionine, lanthionine, Cystathionine, cystine, cysteic acid, aspartic acid, glutamic acid, S- (carboxymethyl) -cysteine, 4-aminobutyric acid, asparagine, glutamine, azaserine, arginine, canavanine, citrulline, δ-hydroxy-lyl , Creatine, kynurenine, histidine, 1-methyl-histidine, 3-methyl-histidine, ergothioneine, tryptophan, glycylglycine, glycylglycylglycine, vasopressin, oxytocin, cassinin, eledoisin, glucagon, secretin, proopiomelanocortin, Examples include enkephalin and prodinorphine.

  Among the components (B), a low molecular weight amino acid is preferable from the viewpoint of achieving a high CMP rate and a low etching rate to a higher degree. Specifically, an amino acid having a molecular weight of 300 or less is preferred, an amino acid having a molecular weight of 250 or less is more preferred, and an amino acid having a molecular weight of 200 or less is more preferred. Examples of such amino acids include α-alanine (molecular weight 89), β-alanine (molecular weight 89), serine (molecular weight 105), histidine (molecular weight 155), glycylglycine (molecular weight 132), glycylglycylglycine (molecular weight 189). ) And the like.

  The content of the component (B) is preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more with respect to 100 parts by mass of the polishing liquid, from the viewpoint that the cobalt-containing part is sufficiently dissolved. 0.001 part by mass or more is more preferable, 0.005 part by mass or more is particularly preferable, and 0.01 part by mass or more is very preferable. In addition, the content of the component (B) is preferably 50 parts by mass or less, more preferably 25 parts by mass or less, and still more preferably 10 parts by mass or less with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily suppressing etching. 5 parts by mass or less is particularly preferable, and 1 part by mass or less is extremely preferable.

  In one Embodiment, it is preferable that content of (B) component is 0.1-0.5 mass part with respect to 100 mass parts of polishing liquid. Thereby, a high CMP rate and a low etching rate can be achieved to a higher degree.

((C) Carboxylic acid and carboxylic acid derivative)
The polishing liquid according to the present embodiment contains at least one selected from the group consisting of carboxylic acids and carboxylic acid derivatives (excluding the component (A) and the component (B)). Although it is thought that (C) component functions as a complexing agent with respect to a cobalt containing part, it is not limited to this. Component (C) includes saturated fatty acids, unsaturated carboxylic acids, hydroxy acids, aromatic carboxylic acids, dicarboxylic acids, carboxylic acids such as oxocarboxylic acids; carboxylic acid derivatives (for example, carboxylic acid esters and carboxylic acid salts), etc. Is mentioned.

  As component (C), formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptane Acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, diglycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, gluconic acid Carboxylic acids such as adipic acid, pimelic acid, maleic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, citric acid and lactic acid; esters of the carboxylic acid (ethyl acetate, pentyl acetate, ethyl lactate, etc.); And salts thereof (such as ammonium acetate).

  The polishing liquid according to this embodiment is composed of phthalic acid and a phthalic acid derivative (phthalic acid ester, phthalic acid salt, etc.) as the component (C) from the viewpoint of achieving a high CMP rate and a low etching rate to a higher degree. It is preferable to contain at least one phthalic acid component selected from the group. Among the phthalic acid components, a phthalic acid component containing a hydrophobic group is preferable from the viewpoint of achieving a high CMP rate and a low etching rate to a higher degree. Examples of such phthalic acid components include alkylphthalic acid, nitrophthalic acid, aminophthalic acid, and the like, and specific examples include 4-methylphthalic acid, 3-nitrophthalic acid, 2-aminophthalic acid, 4-aminophthalic acid, and the like. It is done.

  The content of the component (C) is preferably 0.00001 parts by mass or more, more preferably 0.00005 parts by mass or more with respect to 100 parts by mass of the polishing liquid, from the viewpoint that the cobalt-containing part is sufficiently dissolved. 0.0001 parts by mass or more is more preferable, 0.0005 parts by mass or more is particularly preferable, and 0.001 parts by mass or more is extremely preferable. Further, the content of the component (C) is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and 0.5 part by mass or less with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily suppressing etching. More preferred is 0.1 parts by mass or less, and particularly preferred is 0.05 parts by mass or less.

  In particular, when the polishing liquid contains a component (C) other than the phthalic acid component, the content of the component (C) other than the phthalic acid component is 100 parts by weight of the polishing liquid from the viewpoint that the cobalt-containing part is easily dissolved. Is preferably 0.00001 parts by mass or more, more preferably 0.00005 parts by mass or more, still more preferably 0.0001 parts by mass or more, particularly preferably 0.0005 parts by mass or more, and more preferably 0.001 parts by mass or more. Highly preferred. Further, the content of the component (C) other than the phthalic acid component is preferably 5 parts by mass or less, more preferably 1 part by mass or less, with respect to 100 parts by mass of the polishing liquid, from the viewpoint of easily suppressing etching. 5 parts by mass or less is more preferable, 0.1 parts by mass or less is particularly preferable, and 0.05 parts by mass or less is extremely preferable.

  In particular, when the polishing liquid contains a phthalic acid component, the content of the phthalic acid component is preferably 0.00001 parts by mass or more with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily dissolving the cobalt-containing part. 0.00005 parts by mass or more, more preferably 0.0001 parts by mass or more, particularly preferably 0.0005 parts by mass or more, and extremely preferably 0.001 parts by mass or more. Further, the content of the phthalic acid component is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and further preferably 0.5 parts by mass or less with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily suppressing etching. Preferably, 0.1 mass part or less is especially preferable, and 0.05 mass part or less is very preferable.

  In one embodiment, it is preferable that content of a phthalic acid component is 0.001-0.05 mass part with respect to 100 mass parts of polishing liquid. Thereby, a high CMP rate and a low etching rate can be achieved to a higher degree.

((D) Compound having benzotriazole skeleton)
The polishing liquid according to this embodiment contains a compound having a benzotriazole skeleton. A compound having a benzotriazole skeleton (hereinafter referred to as “benzotriazole compound”) is considered to function as a protective film forming agent, an anticorrosive agent, and the like for the cobalt-containing portion, but is not limited thereto.

  Examples of the benzotriazole compound include 1H-benzotriazole, 5-methyl-1H-benzotriazole (also known as tolyltriazole), 5-hexyl-1H-benzotriazole, 1-hydroxy-1H-benzotriazole, 4-hydroxy- 1H-benzotriazole, 1- (2,3-dihydroxypropyl) -1H-benzotriazole, 1-carboxy-1H-benzotriazole, 4-carboxy-1H-benzotriazole, 4-carboxy-1H-benzotriazole methyl ester, 4-carboxy-1H-benzotriazole butyl ester, 4-carboxy-1H-benzotriazole octyl ester, 2,3-dicarboxypropyl-1H-benzotriazole, N- (1,2,3-benzotriazolyl 1-methyl)-N-(1,2,4-triazolyl-1-methyl) -2-ethylhexanoic amine.

  The content of the benzotriazole compound is preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, and 0.001 parts by mass or more with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily suppressing etching. Is more preferable, and 0.005 parts by mass or more is particularly preferable. In addition, the content of the benzotriazole compound is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and 0.5 part by mass or less with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily obtaining a sufficient CMP rate. Is more preferable, 0.1 part by mass or less is particularly preferable, and 0.05 part by mass or less is very preferable.

  In one Embodiment, it is preferable that content of a benzotriazole compound is 0.005-0.05 mass part with respect to 100 mass parts of polishing liquid. Thereby, a high CMP rate and a low etching rate can be achieved to a higher degree.

(Metal oxidizer)
The polishing liquid according to this embodiment may further contain a metal oxidant (hereinafter referred to as “metal oxidant”). Examples of the metal oxidant include hydrogen peroxide (H ₂ O ₂ ), potassium periodate, ozone, and the like. Of the metal oxidants, hydrogen peroxide is preferred.

  When the polishing liquid contains a metal oxidizing agent, the content of the metal oxidizing agent is 0.1 parts by mass with respect to 100 parts by mass of the polishing liquid from the viewpoint that cobalt is sufficiently oxidized and a good CMP rate is easily obtained. The above is preferable, 0.5 parts by mass or more is more preferable, and 1 part by mass or more is more preferable. Further, the content of the metal oxidizer is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, more preferably 6 parts by mass with respect to 100 parts by mass of the polishing liquid from the viewpoint of preventing the surface to be polished from being rough. The following is more preferable.

(Abrasive grains)
The polishing liquid according to the present embodiment may further contain polishing abrasive grains (hereinafter, simply referred to as “abrasive grains” in some cases). As abrasive grains, inorganic abrasive grains such as silica particles, alumina particles, ceria particles, titania particles, zirconia particles, germania particles, and silicon carbide particles; organic abrasive grains such as polystyrene particles, polyacrylic particles, and polyvinyl chloride particles; inorganic materials Examples include composite abrasive grains of abrasive grains and organic abrasive grains. As the abrasive grains, the dispersion stability in the polishing liquid is good, and from the viewpoint that the number of polishing scratches generated during polishing is small, inorganic abrasive grains are preferable, colloids of inorganic abrasive grains are more preferable, and colloidal silica or colloidal alumina is further provided. preferable.

  The average particle size of the abrasive grains is not particularly limited, but is preferably 100 nm or less and more preferably 80 nm or less from the viewpoint of excellent dispersion stability. Further, the average grain size of the abrasive grains is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more from the viewpoint of easily obtaining a high CMP rate. The “average particle diameter” of the abrasive grains means the average secondary particle diameter of the abrasive grains in the polishing liquid (including the diluted polishing liquid). In measuring the average particle size of the abrasive grains, for example, a light diffraction / scattering particle size distribution meter (“COULTER N4SD” manufactured by COULTER Electronics, “Zetasizer 3000HSA” manufactured by Malvern Instruments, etc.) can be used.

  When the polishing liquid contains abrasive grains, the content of the abrasive grains is 10 parts by mass or less with respect to 100 parts by mass of the polishing liquid from the viewpoint of suppressing a decrease in dispersion stability of the abrasive grains in the polishing liquid. Is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and particularly preferably 0.5 parts by mass or less. The content of abrasive grains is preferably 0 parts by mass or more, more preferably 0.01 parts by mass or more, and 0.05 parts by mass or more with respect to 100 parts by mass of the polishing liquid from the viewpoint of easily obtaining a high CMP rate. Is more preferable. From these viewpoints, the content of the abrasive grains is preferably 0 to 10 parts by mass with respect to 100 parts by mass of the polishing liquid.

(Inorganic acid component)
The polishing liquid according to this embodiment may further contain an inorganic acid component for the purpose of further improving the CMP rate. Inorganic acid components include inorganic acids and salts of inorganic acids. Examples of the inorganic acid component include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid and chromic acid; salts of the inorganic acids (for example, ammonium salts such as ammonium sulfate and ammonium nitrate) and the like. When the polishing liquid contains an inorganic acid component, the total content of the inorganic acid component and the organic acid is preferably in the range of 0.001 to 10 parts by mass with respect to 100 parts by mass of the polishing liquid.

  However, from the viewpoint of easily achieving a low etching rate, the contents of sulfuric acid and sulfate in the polishing liquid are preferably small. By reducing the contents of sulfuric acid and sulfate, it is considered that active dissolution of the cobalt-containing part is suppressed, and a low etching rate is easily realized. Accordingly, the content of sulfuric acid and sulfate in the polishing liquid is preferably 1 ppm (0.0001 mass%) or less, more preferably 0.5 ppm (0.00005 mass%) or less, and 0.1 ppm (0.00001 mass). %) Or less is more preferable. In particular, when the contents of sulfuric acid and sulfate are 0.000 ppm, active dissolution of the cobalt-containing part is suppressed, so that a lower etching rate can be achieved to a higher degree.

  In this specification, “the content of sulfuric acid and sulfate” refers to the content of any one of the sulfuric acid and the sulfate when the polishing liquid contains either sulfuric acid or the sulfate. In the case of containing both sulfate and sulfate, it means the total content of both. Further, as the “sulfate content”, a value obtained by converting the mass of sulfate contained in the polishing liquid into the mass of sulfuric acid is used. For example, the content of ammonium sulfate is determined by [(mass of sulfate contained in polishing liquid) × (98.1 / 132.1)] / (mass of the entire polishing liquid).

  The contents of sulfuric acid and sulfate in the polishing liquid can be determined using the sulfate ion concentration obtained by ion chromatography. Further, the contents of sulfuric acid and sulfate in the polishing liquid can also be determined from the amount of sulfuric acid and sulfate added. In the polishing liquid according to this embodiment, the content of sulfuric acid and sulfate obtained by at least one of the methods is preferably within the above range.

  Examples of the ion chromatography include a system using an electrical conductivity detector as a detector (for example, “ICS-2000” manufactured by Dionex Co., Ltd.). Regarding the measurement conditions, for example, AS20 (4 mmφ × 200 mm) as the column, 30 ° C. as the column temperature, 1.0 mL / min as the flow rate, and 25 μL as the sample injection amount can be adopted. The sample can be prepared by ultrafiltration or dilution of the polishing liquid.

(Protective film forming agent and anticorrosive agent)
The polishing liquid according to this embodiment may further contain a known compound that functions as a protective film forming agent, an anticorrosive agent and the like in addition to the benzotriazole compound. Examples of such a compound include a nitrogen-containing heterocyclic compound, specifically, a compound having a triazole skeleton, a compound having a naphthotriazole skeleton, a compound having a pyrimidine skeleton, a compound having an imidazole skeleton, and a guanidine skeleton. A compound having a thiazole skeleton, a compound having a pyrazole skeleton, and the like. From the viewpoint of easily suppressing etching, a compound having a triazole skeleton, a compound having a naphthotriazole skeleton, and the like are preferable.

  Examples of the compound having a triazole skeleton include 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 4-amino-4H-1,2,4- And triazole.

  Examples of the compound having a naphthotriazole skeleton include 1H-naphtho [2,3-d] triazole 1-amine, 1-amino-1H-naphtho [1,2-d] triazole, 2-amino-2H-naphtho [1, 2-d] triazole, 3H-naphtho [1,2-d] triazole, 4,9-dihydro-1H-naphtho [2,3-d] triazole, and the like.

  When a compound that functions as a protective film forming agent, an anticorrosive or the like is included in addition to the benzotriazole compound, the content of the compound is within a range of 0.001 to 0.5 parts by mass with respect to 100 parts by mass of the polishing liquid. Preferably there is.

(Organic solvent)
The polishing liquid according to this embodiment may further contain an organic solvent (except for the components (A) to (D)). Examples of the organic solvent include carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactones such as butyl lactone and propyl lactone; ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, Glycols such as triethylene glycol and tripropylene glycol; ethers such as tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate; methanol, ethanol, propanol, n -Butanol, n-pentanol, n- Alcohols such as xanol, isopropanol, 3-methoxy-3-methyl-1-butanol (eg, monoalcohols); ketones such as acetone and methyl ethyl ketone; amides such as dimethylformamide and N-methylpyrrolidone; esters (carbonic acid) Excluding esters and lactones); sulfolanes such as sulfolane.

  When the polishing liquid contains an organic solvent, the content of the organic solvent is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the polishing liquid from the viewpoint of improving the solubility of each added component. 05 parts by mass or more is more preferable, and 0.1 parts by mass or more is more preferable. Further, the content of the organic solvent is preferably 50 parts by mass or less, more preferably 10 parts by mass or less, and more preferably 5 parts by mass with respect to 100 parts by mass of the polishing liquid from the viewpoint of stably storing the polishing liquid for a long period of time. The following is more preferable.

(water)
The polishing liquid according to this embodiment may further contain water. As water, it is preferable to use pure water such as ion-exchanged water or distilled water. When the polishing liquid contains water, the content of water may be the remainder of the other components.

(Other optional ingredients)
The polishing liquid according to this embodiment further contains additives such as dispersants and surfactants used in general metal polishing liquids as optional components other than those listed above in consideration of the effects obtained. May be.

(PH)
The pH of the polishing liquid according to this embodiment is preferably 4.0 to 8.0. If the pH of the polishing liquid is 4.0 or more, etching is easily suppressed. The pH of the polishing liquid is more preferably 4.5 or more, and even more preferably 5.0 or more, from the viewpoint of easily suppressing etching. Further, when the pH of the polishing liquid is 8.0 or less, a sufficient CMP rate can be easily obtained. The pH of the polishing liquid is preferably 6.0 or less, more preferably 5.5 or less, from the viewpoint of easily obtaining a sufficient CMP rate.

  In particular, when the pH is 5.0 to 8.0, the CMP rate specifically increases while suppressing the etching rate. Thereby, a high CMP rate and a low etching rate can be achieved to a higher degree.

  The pH of the polishing liquid according to this embodiment may be adjusted using an acid or a base as a pH adjuster. Examples of the pH adjuster include the component (C); the inorganic acid component such as hydrochloric acid and nitric acid; and the inorganic base such as sodium hydroxide, potassium hydroxide, and ammonia.

  The pH can be measured using a pH meter (for example, “pHMeter F-51” manufactured by Horiba, Ltd.). For example, after calibrating two pH meters using a phthalate pH buffer solution (pH 4.01) and a neutral phosphate pH buffer solution (pH 6.86) as standard buffers, Is measured in the polishing liquid after 2 minutes or more has elapsed and stabilized. At this time, both the standard buffer solution and the polishing solution are set to 25 ° C.

(Polishing liquid set)
The polishing liquid according to this embodiment may be stored as a multi-liquid polishing liquid set in which the constituent components are divided into slurry and additive liquid. A slurry and an additive liquid can be mixed to obtain a polishing liquid. The slurry includes at least abrasive grains and water, for example. The additive liquid contains, for example, at least one selected from the group consisting of (A) component, (B) component, (C) component, (D) component, and metal oxidizer. In particular, when components that are easily decomposed, such as hydrogen peroxide as a metal oxidizing agent, are used, it is preferable to store the components separately. For example, it is preferable to store the slurry separately in a slurry containing abrasive grains, (A) component, (B) component, (C) component, (D) component and water, and an additive solution containing hydrogen peroxide and water.

  In addition, the slurry and the additive liquid may be a concentrated storage liquid that is diluted with a liquid medium such as water. Here, the concentration means that the content ratio of each component with respect to the liquid medium is larger than the content ratio in the polishing liquid, and is not limited to the one that has undergone the concentration step.

<Polishing method>
The polishing method according to the present embodiment includes a step of polishing at least the cobalt-containing portion using the polishing liquid according to the present embodiment. The object to be polished in the polishing method according to the present embodiment is, for example, a substrate having a surface having a cobalt-containing portion, and the polishing method according to the present embodiment uses, for example, the polishing liquid according to the present embodiment to contain cobalt. A step of polishing at least the cobalt-containing portion of a substrate having a surface having a portion. The said surface of the said board | substrate does not need to have a copper containing part. Examples of the substrate to be polished include a substrate for manufacturing a semiconductor device. The cobalt-containing part is a part containing a cobalt atom, and is, for example, at least one selected from the group consisting of cobalt, a cobalt alloy (for example, a cobalt-nickel alloy, etc.), a cobalt oxide, and a cobalt alloy oxide. Of cobalt-based metals. The copper-containing part is a part containing a copper atom, and includes, for example, at least one copper-based metal selected from the group consisting of copper, a copper alloy, a copper oxide, and a copper alloy oxide. The substrate to be polished is preferably formed by depositing a cobalt-based metal on a base layer (base, layer formed using an interlayer insulating material, etc.) having a convex portion and a concave portion on the surface to form a cobalt-containing portion. A substrate in which a concave portion is filled with a cobalt-based metal. When such a substrate is polished using the polishing liquid according to the present embodiment, the cobalt-based metal deposited on the convex portion of the underlayer is selectively removed by polishing, and is made of a desired flattened cobalt-based metal. A wiring pattern is obtained.

  In one embodiment of the polishing method, for example, as shown in FIG. 1A, a substrate 10 having a base layer (base) 1, a barrier layer 2, and a cobalt-containing portion 3 is polished. The underlayer 1 is made of an interlayer insulating material. The underlayer 1 has a base portion 1a and a plurality of raised portions 1b arranged on the base portion 1a, and has a convex portion and a concave portion on the surface. The barrier layer 2 is made of a barrier material and is provided following the surface of the underlayer 1. The cobalt-containing portion 3 covers the barrier layer 2 so as to fill the concave portion. In one embodiment of the polishing method, for example, the cobalt-containing portion 3 is polished using the polishing liquid according to this embodiment, and a barrier positioned on the convex portion of the base layer 1 as shown in FIG. A first polishing step for obtaining the substrate 20 by exposing the layer 2 is provided. In one embodiment of the polishing method, the barrier layer 2 on the convex portion is further polished to expose the base layer 1 constituting the convex portion to obtain the substrate 30 as shown in FIG. Two polishing steps may be provided. For polishing the barrier layer 2, a known polishing liquid for the barrier layer may be appropriately selected and used according to the material forming the barrier layer.

  For the polishing method according to this embodiment, for example, a general polishing apparatus having a holder that can hold a substrate and a polishing surface plate to which a polishing pad is attached can be used. The polishing liquid according to the present embodiment is supplied onto the polishing pad of the polishing platen, and the surface to be polished is moved by relatively moving the polishing platen and the substrate while pressing the cobalt-containing portion of the substrate against the polishing pad. Can be polished.

  In the case of using a polishing apparatus, for example, it generally has a holder that can hold a substrate to be polished, and a polishing platen that can be attached to a polishing pad and connected to a motor that can change the number of rotations. A typical polishing apparatus can be used. Examples of the polishing pad include pads made of nonwoven fabric, polyurethane foam, porous fluororesin, and the like.

The polishing conditions are not particularly limited, but the rotation speed of the polishing surface plate is preferably a low rotation of 200 min ⁻¹ (200 rpm) or less so that the substrate does not jump out. The pressure for pressing the substrate to the polishing pad is preferably 4.9 to 98 kPa. From the viewpoint of satisfying that there is little variation in the CMP rate within the same plane (in-plane uniformity of the CMP rate), and that the unevenness that existed before polishing is eliminated and the surface is likely to become flat (pattern flatness). 9.8 to 49 kPa is more preferable.

  During polishing, for example, the polishing liquid is continuously supplied to the polishing pad with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid. The substrate after polishing is preferably washed in running water and then dried after removing water droplets attached to the substrate using spin drying or the like.

  Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to these examples.

<Example 1>
(Preparation of polishing liquid)
In pure water, methanol as an organic solvent, glycine and α-alanine as an amino acid (component (A) and component (B)), 4-methylphthalic acid (4M-phthalic acid) as a carboxylic acid (component (C)), and After adding 5-methylbenzotriazole (5M-BTA) as a benzotriazole compound (component (D)) in this order, the solution was obtained by stirring and mixing. To the resulting solution, colloidal silica was added as abrasive grains and mixed. Further, hydrogen peroxide water (hydrogen peroxide concentration: 30% by mass) was added and mixed. Thereafter, pure water was added and mixed so that the content of each component was the amount shown in Table 1 [unit: mass%], and the polishing liquid of Example 1 was obtained.

(Average grain size of abrasive grains)
The average particle size of the abrasive grains (average particle size of secondary particles) was measured using a light diffraction scattering type particle size distribution meter (“Zeta Sizer 3000HSA” manufactured by Malvern Instruments). Specifically, after preparing the sample by diluting the polishing liquid with ion-exchanged water (scattered light intensity is 500 to 2000 cps), it is put into the sample tank of the particle size distribution meter and electrophoretic movement calculated from the scattered light intensity The value obtained as a degree was read. The average particle size of the colloidal silica was 70 nm.

(PH of polishing liquid)
The pH of the polishing liquid was measured under the following conditions. The results are shown in Table 1.
Measurement temperature: 25 ° C
Measuring device: “pHMeter F-51” manufactured by HORIBA, Ltd.
Measurement method: Two-point calibration using a standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C.); neutral phosphate pH buffer, pH: 6.86 (25 ° C.)) Thereafter, the electrode was placed in the polishing liquid, and the pH after being stabilized after 2 minutes or more was measured with the measuring device.

(Polishing property evaluation)
The polishing characteristics of the polishing liquid obtained above were evaluated according to the following evaluation items. The results are shown in Table 1.

[Evaluation item]
(1) CMP rate (Co-RR (Removal Rate) [nm / min])
The difference in thickness of the cobalt layer before and after CMP was calculated from the electrical resistance value, and the CMP rate was calculated from the thickness difference and the polishing time.

{Polishing conditions}
Substrate: silicon wafer having a cobalt layer with a thickness of 200 nm formed on the surface (12 inch, blanket wafer, substrate having a cobalt-containing part and no copper-containing part)
Polishing device: Surface plate diameter 1200 mm, rotary type Polishing pad: Foam polyurethane resin having closed cells ("IC-1010" manufactured by Rohm and Haas)
Polishing pressure: 14 kPa
Relative speed between substrate and polishing surface plate: 36 m / min
Polishing liquid supply amount: 300 mL / min
Polishing liquid temperature: 25 ° C
Polishing time: 20 sec

(2) Etching rate (Co-ER (Etching Rate) [nm / min])
The chip was immersed in a polishing liquid, the difference in thickness of the cobalt layer before and after immersion was calculated from the electrical resistance value, and the etching rate was calculated from the difference in thickness and the immersion time.

{Immersion conditions}
Chip: 20 mm × 20 mm chip obtained by cutting a silicon wafer (8 inch, blanket wafer) having a cobalt layer with a thickness of 200 nm on the surface. Polishing liquid capacity: 100 mL in a 100 mL beaker
Stirring speed: 200 min ⁻¹ (rpm)
Polishing liquid temperature: 60 ° C
Immersion time: 5 min

<Examples 2 to 6>
(B) A polishing liquid was obtained in the same manner as in Example 1 except that the component was changed to the chemical species shown in Table 1 (β-alanine, serine, histidine, glycylglycine, glycylglycylglycine). In the same manner as in Example 1, the average particle size of the abrasive grains and the pH of the polishing liquid were measured, and the CMP rate and the etching rate were evaluated. The results are shown in Table 1.

<Examples 7 and 8 and Comparative Examples 1 to 6>
A polishing liquid was obtained in the same manner as in Example 1 except that the content and content of the polishing liquid were changed to the content and content of Table 2. In the same manner as in Example 1, the average particle size of the abrasive grains and the pH of the polishing liquid were measured, and the CMP rate and the etching rate were evaluated. The results are shown in Table 2.

<Examples 9 and 10 and Comparative Example 3>
A polishing liquid was obtained in the same manner as in Example 1 except that the content and content of the polishing liquid were changed to the content and content of Table 3. In the same manner as in Example 1, the average particle size of the abrasive grains and the pH of the polishing liquid were measured, and the CMP rate and the etching rate were evaluated. The results are shown in Table 3 together with the results of Example 1.

<Examples 11 and 12>
A polishing liquid was obtained in the same manner as in Example 1 except that the content and content of the polishing liquid were changed to the content and content of Table 4. In the same manner as in Example 1, the average particle size of the abrasive grains and the pH of the polishing liquid were measured, and the CMP rate and the etching rate were evaluated. The results are shown in Table 4 together with the results of Example 1. In Table 4, the content [unit: mass%] of sulfuric acid and ammonium sulfate is a value determined based on the addition amount, and the content [mass%] of ammonium sulfate is the mass of ammonium sulfate contained in the polishing liquid. Is a value obtained by converting to the mass of sulfuric acid.

<Examples 13 to 18 and Comparative Example 4>
A polishing liquid was obtained in the same manner as in Example 1 except that the content and content of the polishing liquid were changed to the content and content of Table 5. In the same manner as in Example 1, the average particle size of the abrasive grains and the pH of the polishing liquid were measured, and the CMP rate and the etching rate were evaluated. The results are shown in Table 5 together with the results of Example 1. In Table 5, “BTA” represents 1H-benzotriazole, and “HBTA” represents 4-hydroxybenzotriazole.

  As shown in Tables 1 to 5, in Examples 1 to 18, the polishing liquid contains (A) component, (B) component, (C) component and (D) component, so that high CMP rate and low etching are achieved. We were able to achieve a high balance between speed. The reason why the high CMP rate can be achieved is presumed that the component (C) effectively complexes the ions eluted by polishing. On the other hand, it is speculated that the reason why the low etching rate can be achieved is that the addition of the component (A) and the component (B) suppresses the decrease in pH, so that the active dissolution of cobalt due to the low pH can be suppressed. From this point of view, it can be said that in the embodiment, the effect of highly achieving a high CMP rate and a low etching rate is effectively exhibited.

  As shown in Examples 5 and 6 of Table 1, it can be seen that even when the peptides glycylglycine and glycylglycylglycine are used, a high CMP rate and a low etching rate can be achieved at a high level.

  As shown in Table 3, it can be seen that even when the content of the component (C) is adjusted, a high CMP rate and an etching rate can be achieved to a high degree.

  As shown in Table 4, it can be seen that a higher CMP rate can be achieved when an inorganic acid component is used.

  As shown in Table 5, it can be seen that even when various chemical species are used as the component (D), high CMP rate and high etching rate can be achieved to a high degree.

  The polishing liquid and the polishing method according to the embodiment of the present invention can be preferably used for CMP of a substrate having a cobalt-containing portion (for example, a semiconductor substrate having a cobalt-based metal as a wiring material). At least the cobalt-containing portion of the substrate having a surface having a surface can be polished at a high CMP rate and a low etching rate.

  DESCRIPTION OF SYMBOLS 1 ... Base layer, 1a ... Base part, 1b ... Raised part, 2 ... Barrier layer, 3 ... Cobalt containing part, 10, 20, 30 ... Substrate.

Claims (8)

A polishing liquid for polishing at least the cobalt-containing part of a substrate comprising a surface having a cobalt-containing part,
(A) glycine;
(B) at least one selected from the group consisting of amino acids and amino acid derivatives (excluding the component (A)),
(C) at least one selected from the group consisting of a carboxylic acid and a carboxylic acid derivative (excluding the component (A) and the component (B)),
(D) A polishing liquid comprising a compound having a benzotriazole skeleton.   The polishing liquid according to claim 1, wherein the surface of the substrate does not have a copper-containing portion.   The polishing liquid according to claim 1 or 2, wherein the pH is 4.0 to 8.0.   The polishing liquid according to any one of claims 1 to 3, wherein the component (C) contains at least one selected from the group consisting of phthalic acid and phthalic acid derivatives.   The polishing liquid according to any one of claims 1 to 4, further comprising at least one selected from the group consisting of hydrogen peroxide, potassium periodate, and ozone.   The polishing liquid according to any one of claims 1 to 5, further comprising abrasive grains.   The grinding | polishing method of grind | polishing at least the said cobalt containing part of a board | substrate provided with the surface which has a cobalt containing part using the polishing liquid as described in any one of Claims 1-6.   The polishing method according to claim 7, wherein the surface of the substrate does not have a copper-containing portion.

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