JP2017107918A - Polishing liquid for cmp and manufacturing method thereof, and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing liquid for CMP (Chemical Mechanical Polishing), by which the rate of etching a cobalt-containing part can be kept down while retaining a good polishing speed on the cobalt-containing part.SOLUTION: A polishing liquid for CMP is arranged for polishing a surface of a substrate to be polished, provided that the substrate has an insulative material part 21, a cobalt-containing part 22a, and a titanium-containing part 22b gluing the insulative material part with the cobalt-containing part, and the cobalt-containing part is exposed from the surface to be polished. The polishing liquid comprises: a methacrylic acid-based polymer having a structural unit originating the reaction of a monomer component including at least methacrylic acid under a condition in which no inorganic acid is present; abrasion particles; a metal corrosion inhibitor; and water.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a polishing liquid for CMP, a method for producing the same, 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”). A chemical mechanical polishing (hereinafter referred to as “CMP”) method is one of them. The CMP method is a technique frequently used in planarization of an insulating material portion, formation of a metal plug, formation of a buried wiring, and the like in an LSI manufacturing process (particularly, a multilayer wiring forming process).

  In recent years, a so-called damascene method has been adopted for the formation of embedded wiring. In the damascene method, a conductive material is deposited on an insulating material portion in which a concave portion (for example, a groove portion) and a convex portion (for example, a raised portion) are formed on the surface in advance, and the conductive material is embedded in the concave portion. Next, the conductive material portion deposited on the convex portion (that is, the conductive material portion other than in the concave portion) is removed by CMP to form a buried wiring.

  In the CMP of the conductive material portion, for example, first, a polishing pad is attached on a circular polishing platen (platen), and the surface of the polishing pad is immersed in a CMP polishing liquid. Next, the surface on which the conductive material portion of the substrate is formed is pressed against the polishing pad, and a predetermined pressure (hereinafter referred to as “polishing pressure”) is applied from the back surface of the substrate. Thereafter, the polishing surface plate is rotated in this state, and the conductive material portion on the convex portion is removed by mechanical friction between the CMP polishing liquid and the conductive material portion.

  On the other hand, as shown in FIG. 3A, a liner portion 2 is usually formed between the insulating material portion 1 having irregularities and the conductive material portion 3 provided on the insulating material portion 1. Is done. The purpose of providing the liner portion 2 is to prevent the conductive material of the conductive material portion 3 from diffusing into the insulating material portion 1, to improve the adhesion between the insulating material portion 1 and the conductive material portion 3, etc. It is. The liner portion 2 is formed of a barrier metal (hereinafter sometimes referred to as “barrier metal”). Since the barrier metal is a conductor, it is necessary to remove the barrier metal in the same manner as the conductive material except for the concave portion (that is, the wiring portion) in which the conductive material is embedded.

  These removals include a “first polishing step” in which the conductive material portion 3 is polished from the state shown in FIG. 3A to the state shown in FIG. 3B, and the state shown in FIG. 2 stage polishing in which the liner part 2 and the conductive material part 3 are polished from the state shown in FIG. 3C to the state shown in FIG. The method is generally applied.

  By the way, with the miniaturization of design rules, the thickness of each part tends to be thin. However, when the liner part 2 is thinned, the effect of preventing the diffusion of the conductive substance is reduced. In addition, the adhesion with the conductive material portion 3 tends to decrease. Furthermore, since the wiring width becomes narrower, it becomes difficult to embed the conductive material in the recess (that is, the embedding property is lowered), and voids called “voids” are easily generated in the conductive material portion 3. New challenges arise.

  For this reason, the use of cobalt (Co) as a barrier metal is studied, and a method in which a copper-based metal such as copper or a copper alloy is not used for the conductive material portion 3 is also studied. By using cobalt for these, the concern about embedding is reduced. Furthermore, the adhesion between the insulating material and the conductive material can be supplemented.

  When cobalt is used for the liner portion 2 or the conductive material portion 3, it is necessary to use a polishing slurry for CMP that can remove cobalt. Various CMP polishing liquids for metals are known, but when there is a CMP polishing liquid, it cannot always remove any metal. As conventional CMP polishing liquids for metals, those for which the object to be removed by polishing is a metal such as copper, tantalum, titanium, tungsten, and aluminum are known. However, there are few known polishing liquids for CMP that use cobalt as a polishing target, although several examples have been reported as in Patent Documents 1 to 3 below.

JP 2011-91248 A JP 2012-182158 A JP2013-42123A

  According to the knowledge of the present inventors, cobalt is more corrosive than metals such as copper-based metals that have been used as conductive materials. Cobalt is excessively etched or slits are formed in the wiring pattern. As a result, there is a concern that metal ions diffuse into the insulating material portion without fulfilling the function as the liner portion. When metal ions diffuse into the insulating material portion, there is a high possibility that a short circuit occurs in the semiconductor device.

  The present invention is intended to solve the above-described problem, and provides a polishing slurry for CMP capable of suppressing the etching rate of the cobalt-containing portion, a manufacturing method thereof, and a polishing method using the polishing slurry. Objective.

  As a result of the study by the present inventors, it has been found that when the polishing liquid contains a polymer as a constituent component, the etching rate of the cobalt-containing portion increases depending on the type of polymer contained in the polishing liquid. For example, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], which is a water-soluble azo polymerization initiator that can be used as a polymerization initiator in the synthesis of a polymer, is an acidic aqueous solution. In general, the polymerization initiator is dissolved using an inorganic acid such as sulfuric acid. In this case, the polymer contains several moles of inorganic acid. It has been found that when a conventional polishing liquid using a polymer containing such an inorganic acid is used, the cobalt-containing portion is excessively etched or slits are generated. When the etching rate of the cobalt-containing part is high, when the cobalt-containing part is used as the liner part, the cobalt-containing part may be excessively eroded or a slit may be formed in the wiring pattern. Therefore, there is a problem that the cobalt-containing part does not function as a liner part.

  As a result of diligent studies to solve such conventional problems, the present inventors have improved the synthesis method of methacrylic acid polymer after using methacrylic acid polymer as a constituent of polishing liquid. Was found to be an important point.

  In addition, in a substrate having an insulating material part and a cobalt-containing part, the problem of “EM (electromigration)” in which cobalt in the cobalt-containing part diffuses and reaches the insulating material part may occur, resulting in a decrease in reliability. It is desirable to improve resistance. Therefore, it is desirable to introduce a barrier layer that bonds the insulating material part and the cobalt-containing part between the insulating material part and the cobalt-containing part. However, as the structure becomes finer, the barrier layer further increases the EM resistance. At the same time, it is desired that the adhesiveness with the cobalt-containing part is excellent. The inventors further improve EM resistance and reliability (semiconductor reliability) by using a titanium-containing part as an adhesive layer for bonding the insulating material part and the cobalt-containing part between the insulating material part and the cobalt-containing part. Etc.) and improved adhesion between the barrier layer and the cobalt-containing part was achieved.

  That is, one embodiment of the present invention has an insulating material part, a cobalt-containing part, and a titanium-containing part that adheres the insulating material part and the cobalt-containing part, and the surface to be polished contains the cobalt. A polishing liquid for CMP for polishing the surface to be polished of a substrate having an exposed portion, and having a structural unit derived from a reaction of a monomer component containing at least methacrylic acid under a condition in which no inorganic acid is present The present invention relates to a polishing slurry for CMP, comprising a polymer, abrasive particles, a metal anticorrosive, and water.

  Another embodiment of the present invention has an insulating material part, a cobalt-containing part, and a titanium-containing part that adheres the insulating material part and the cobalt-containing part, and the cobalt-containing part on the surface to be polished A method for producing a polishing slurry for CMP for polishing the surface to be polished of a substrate with exposed portions, wherein the monomer contains at least methacrylic acid in a solution containing an aqueous solvent and a polymerization initiator and no inorganic acid. A process for obtaining a methacrylic acid polymer by polymerizing components, wherein the CMP polishing liquid comprises the methacrylic acid polymer, abrasive particles, a metal anticorrosive, and water. It relates to a manufacturing method.

  According to the polishing slurry for CMP and the manufacturing method thereof according to the embodiment of the present invention, the etching rate of the cobalt-containing portion can be suppressed. According to the polishing slurry for CMP and the manufacturing method thereof according to the embodiment of the present invention, the cobalt-containing part can be protected by effectively suppressing the etching rate of the cobalt-containing part. Further, according to the polishing slurry for CMP and the manufacturing method thereof according to the embodiment of the present invention, by using the titanium-containing portion that bonds the insulating material portion and the cobalt-containing portion, the EM resistance can be further improved and the reliability (semiconductor Reliability, etc.) can be improved, and excellent adhesion between the barrier layer and the cobalt-containing portion can be achieved.

  In addition, in the conventional CMP polishing liquid, in order to suppress the etching rate, if a metal anticorrosive having a strong anticorrosive action is added to the CMP polishing liquid or the amount of the metal anticorrosive is increased, the polishing rate of cobalt is increased. Will fall. On the other hand, according to the polishing slurry for CMP and the manufacturing method thereof according to the embodiment of the present invention, the etching rate of the cobalt-containing portion can be suppressed while maintaining a good polishing rate of the cobalt-containing portion. According to the polishing slurry for CMP and the manufacturing method thereof according to the embodiment of the present invention, it is possible to protect the cobalt-containing portion by effectively suppressing the etching rate of the cobalt-containing portion while maintaining a good polishing rate of the cobalt-containing portion. .

  The aspect which does not have the copper containing part which contains copper as a main component may be sufficient as the to-be-polished surface of the said board | substrate.

  The metal anticorrosive agent preferably contains a triazole. Thereby, the etching of the cobalt-containing part can be further suppressed while maintaining a good polishing rate of the cobalt-containing part.

  The abrasive particles preferably include at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. Thereby, there exists a tendency for the grinding | polishing rate of a metal containing part (for example, the metal containing part provided in the vicinity of a cobalt containing part) to improve further.

  The CMP polishing liquid may further contain a metal oxidant. Thereby, there exists a tendency for the grinding | polishing speed | rate of a metal containing part to improve further.

  The CMP polishing liquid may further contain an organic solvent. Thereby, the wettability with respect to a metal containing part (for example, the metal containing part provided in the vicinity of a cobalt containing part) can be improved, and there exists a tendency for the grinding | polishing rate of the said metal containing part to improve further.

  In the method for producing a polishing slurry for CMP, the aqueous solvent is preferably an embodiment made of water or an embodiment containing organic acids. Thereby, the etching of the cobalt-containing part can be further suppressed while maintaining a good polishing rate of the cobalt-containing part.

  In another embodiment of the present invention, the polishing surface of the substrate is polished by using the CMP polishing liquid or the CMP polishing liquid obtained by the method for producing the CMP polishing liquid. The present invention relates to a polishing method including a step of removing at least a part of a cobalt-containing portion.

  In the polishing method, the surface to be polished may have a metal-containing portion containing a metal other than cobalt.

  According to an embodiment of the present invention, a CMP polishing liquid capable of suppressing etching of a cobalt-containing part while maintaining a good polishing rate of the cobalt-containing part, a manufacturing method thereof, and a polishing method using the polishing liquid are provided. it can.

It is a cross-sectional schematic diagram which shows the grinding | polishing method which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram which shows the grinding | polishing method which concerns on other one Embodiment of this invention. It is a cross-sectional schematic diagram which shows the formation process of the embedded wiring by the conventional damascene method.

In the present specification, the “polishing rate” means a rate at which the substance A to be CMP is removed by polishing (for example, a reduction amount of the thickness of the substance A per time. Removable Rate).
“Process” is not only an independent process, but even if it cannot be clearly distinguished from other processes, it cannot be clearly distinguished from other processes as long as the operations specified in the “process” are performed. A process is also included.
The numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
The content of each component in the CMP polishing liquid is the sum of the plurality of substances present in the CMP polishing liquid unless there is a specific indication when there are a plurality of substances corresponding to each component in the CMP polishing liquid. Means quantity.

  Hereinafter, embodiments of the present invention will be described in detail.

<CMP polishing liquid and manufacturing method thereof>
The CMP polishing liquid and the manufacturing method thereof according to the present embodiment include an insulating material part, a cobalt-containing part, and a titanium-containing part (adhesive layer) that bonds the insulating material part and the cobalt-containing part. In addition, the present invention provides a polishing liquid for CMP for polishing the surface to be polished of the substrate having the cobalt-containing portion exposed on the surface to be polished, and a method for manufacturing the same. The surface of the substrate has the surface to be polished. The surface to be polished of the substrate may have an aspect not having a copper-containing part containing copper as a main component, or an aspect having a copper-containing part.

  The polishing slurry for CMP according to the present embodiment includes a methacrylic acid polymer having a structural unit derived from the reaction of a monomer component containing at least methacrylic acid under conditions in which no inorganic acid is present, abrasive particles, and a metal anticorrosive. And water. The method for producing a polishing slurry for CMP according to this embodiment comprises a polymer that obtains a methacrylic acid polymer by polymerizing a monomer component containing at least methacrylic acid in a solution containing an aqueous solvent and a polymerization initiator and not containing an inorganic acid. A synthesis process is provided. That is, the methacrylic acid polymer is a methacrylic acid polymer obtained by polymerizing a monomer component containing at least methacrylic acid in a solution containing an aqueous solvent and a polymerization initiator and not containing an inorganic acid.

(Methacrylic acid polymer)
The polymer contained in the CMP polishing liquid according to this embodiment needs to be a methacrylic acid polymer obtained without using an inorganic acid (sulfuric acid, nitric acid, etc.) as a raw material for the synthesis. The CMP polishing liquid according to this embodiment contains a methacrylic acid polymer obtained by polymerizing at least a monomer component containing methacrylic acid in a solution containing an aqueous solvent and a polymerization initiator and not containing an inorganic acid. That is, the methacrylic acid polymer has a structural unit derived from the reaction of a monomer component containing at least methacrylic acid under the condition where no inorganic acid is present. The reaction can be performed in the presence of a polymerization initiator. The polymer synthesis step for obtaining the methacrylic acid polymer includes, for example, a step of dissolving a polymerization initiator in an aqueous solvent not containing an inorganic acid to obtain a solution, and a monomer component containing at least methacrylic acid in the solution. You may have the process of making it polymerize and obtaining a methacrylic acid type polymer. Such a methacrylic acid polymer can suppress corrosion on the cobalt-containing portion as compared with a methacrylic acid polymer obtained using an inorganic acid. The methacrylic acid-based polymer of this embodiment has a high adsorptivity to the cobalt-containing part compared to other water-soluble polymers, and is excellent in the protection performance of the cobalt-containing part. It is estimated that it can be reduced.

  The aqueous solvent only needs to contain at least water, and a solvent capable of dissolving the polymerization initiator can be used. The aqueous solvent preferably contains organic acids. It is preferable that the aqueous solvent is an embodiment composed of water (embodiment not containing organic acids) or an embodiment containing water and organic acids (for example, an embodiment composed of water and organic acids). Specific examples of the organic acids will be described later.

  In the polymer synthesis step, there are two types of methods, a case where a water-soluble polymerization initiator is used and a case where a polymerization initiator dissolved in a monomer component containing methacrylic acid is used. In the latter case where a polymerization initiator that dissolves in a monomer component containing methacrylic acid is used, for example, the polymerization initiator is first dissolved once in the monomer component containing methacrylic acid, and then the polymerization initiator is dissolved. By dropping the monomer component containing an acid into an aqueous solvent, a polymer can be obtained while dissolving the polymerization initiator in the aqueous solvent.

  Examples of the polymerization initiator for synthesizing the polymer include a water-soluble azo polymerization initiator and an azo polymerization initiator dissolved in a monomer component containing methacrylic acid. Examples of water-soluble azobis polymerization initiators include 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [N- (2-hydroxyethyl) -2-methyl. Propanamide], 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] and salts thereof. Examples of the azo polymerization initiator dissolved in the monomer component containing methacrylic acid include 2,2'-azo (isobutylnitrile) and salts thereof.

  Examples of the salt of the azo polymerization initiator include ammonium salts, alkali metal salts, alkaline earth metal salts, salts with halides, and the like. The salt of the azo polymerization initiator is not particularly limited, but when the substrate to be polished is a silicon substrate including an integrated circuit element, an alkali metal salt, an alkaline earth metal salt, a halide, etc. It is preferable that it is other than the salt.

  Water-soluble azobis-based polymerization initiators (2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [N- (2-hydroxyethyl) -2-methyl In order to dissolve propanamide], 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] and the like) in an aqueous solvent, the aqueous solvent is preferably adjusted to be acidic. As the acid added to adjust the aqueous solvent to be acidic, by selecting an acid other than the inorganic acid, the etching rate of the cobalt-containing part can be further suppressed while maintaining a good polishing rate of the cobalt-containing part. Corrosion is further suppressed, and an even better polished surface can be obtained. Further, even under severe conditions (for example, 60 ° C. or higher), the etching rate of the cobalt-containing portion is further effectively suppressed.

  Although there is no restriction | limiting in particular in the usage-amount of a polymerization initiator, A polymerization initiator is used so that the molar ratio of a monomer component and a polymerization initiator may be about monomer component: polymerization initiator = 100 mol: 0.1-5 mol. It is preferable to add.

  The acid added to adjust the aqueous solvent to acidity is not particularly limited as long as it is an acid other than an inorganic acid from the viewpoint of further suppressing corrosion of the cobalt-containing part. Examples of such acids include 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and 2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropane. Amide], 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] and the like can be easily adjusted to an acidity capable of dissolving in an aqueous solvent, formic acid, acetic acid, Propionic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, methanesulfonic acid, p-phenol Organic acids such as organic acids such as sulfonic acids, salts of the organic acids, anhydrides of the organic acids, and esters of the organic acids. Among these, at least selected from the group consisting of acetic acid, glycolic acid, glutaric acid, malic acid, citric acid, methanesulfonic acid and p-phenolsulfonic acid from the viewpoint of more effectively suppressing the corrosion of the cobalt-containing part. One type is preferred. The amount of acid used is not particularly limited as long as it is an amount sufficient to dissolve the polymerization initiator in the aqueous solvent, but it is preferably added in an equimolar amount with respect to the polymerization initiator.

  The methacrylic acid polymer is at least one selected from the group consisting of homopolymers of methacrylic acid (homopolymers) and copolymers (copolymers) of methacrylic acid and monomers copolymerizable with the methacrylic acid. Preferably there is.

  Monomers copolymerizable with methacrylic acid include acrylic acid, crotonic acid, vinyl acetic acid, tiglic acid, 2-trifluoromethyl acrylic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, mesaconic acid, gluconic acid, and the like. Carboxylic acids such as 2-acrylamido-2-methylpropane sulfonic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyltyl methacrylate, methacrylic acid Acrylic acid esters such as propyl acid, butyl methacrylate, 2-ethylhexyl methacrylate; salts of these ammonium salts, alkali metal salts, alkylamine salts, and the like. When the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, an ammonium salt is preferable among the salts.

  When the methacrylic acid polymer is a copolymer of methacrylic acid and a monomer copolymerizable with the methacrylic acid, the ratio of methacrylic acid to the total amount of the monomer is preferably 40 mol% or more and less than 100 mol%, more preferably 50 It is more than mol% and less than 100 mol%, more preferably more than 60 mol% and less than 100 mol%, particularly preferably more than 70 mol% and less than 100 mol%. When the ratio of the methacrylic acid is 40 mol% or more, the occurrence of dishing and erosion can be effectively suppressed, and the flatness of the surface to be polished can be easily improved.

  As described above, a higher content of methacrylic acid in a methacrylic acid polymer is more effective in reducing dishing and erosion. However, on the other hand, if attention is paid to the point that defects such as organic residues and scratches can be reduced on the polished surface after polishing, the methacrylic acid polymer is composed of methacrylic acid and a monomer copolymerizable with the methacrylic acid. It is preferred to use a copolymer of The monomer copolymerizable with methacrylic acid is preferably at least one selected from the group consisting of acrylic acid and acrylic acid esters from the viewpoint of being effective in reducing the defects.

  The weight average molecular weight of the methacrylic acid polymer is preferably 3000 or more, more preferably 5000 or more, and still more preferably, from the viewpoint of effectively suppressing the occurrence of dishing and erosion and improving the flatness of the polished surface. Is 6000 or more. The upper limit of the weight average molecular weight is not particularly defined, but is preferably 5 million or less from the viewpoint of excellent solubility. The weight average molecular weight is preferably 1,000,000 or less from the viewpoint of ease of synthesis, ease of molecular weight control, etc., from the viewpoint of excellent solubility in water and increasing the degree of freedom of addition. More preferably, it is 100,000 or less.

The weight average molecular weight of the methacrylic acid polymer can be measured by gel permeation chromatography using a standard polystyrene calibration curve. Specifically, for example, measurement can be performed by size exclusion chromatography using a calibration curve prepared with standard polystyrene under the following measurement conditions.
Column: Shodex Asahipak GS-520HQ + 620HQ manufactured by Showa Denko KK
Pump: Hitachi Ltd. L-71000
_{Eluent: 50mM-Na 2 HPO 4 aq} . / CH ₃ CN = 90/10
Flow rate: 0.6 mL / min
Detector: L-3300 differential refractometer manufactured by Hitachi, Ltd. Data processing: D-2520 GPC integrator manufactured by Hitachi, Ltd. Sample concentration: 10 mg / mL
Injection volume: 5 μL

  The content of the methacrylic acid polymer is preferably 0.001 to 15% by mass, more preferably 0.01 to 5% by mass, in the total mass of the CMP polishing liquid (total amount of all components). When the content of the methacrylic acid polymer is 0.001% by mass or more, generation of erosion and seam is effectively suppressed, and the flatness of the surface to be polished can be easily improved. When the content of the methacrylic acid polymer is 15% by mass or less, the stability of the abrasive particles contained in the polishing liquid is maintained and the dispersibility of the abrasive particles is improved while suppressing the occurrence of dishing and erosion. It becomes easy.

(Abrasive particles)
The CMP polishing liquid contains abrasive particles (abrasive grains). When the polishing slurry for CMP contains abrasive particles, the polishing rate of the metal-containing part (for example, the metal-containing part provided in the vicinity of the cobalt-containing part) tends to be improved. The abrasive particles can be used alone or in combination of two or more.

  Examples of the constituent material of the abrasive particles include inorganic substances such as silica, alumina, ceria, titania, zirconia, germania, and silicon carbide; organic substances such as polystyrene, polyacrylic acid, and polyvinyl chloride; and modified products thereof. The constituent material of the abrasive particles is preferably at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. Examples of the modified product include those obtained by modifying the surface of abrasive particles containing silica, alumina, ceria, titania, zirconia, germania and the like with an alkyl group. As the abrasive particles, particles having no sulfone group may be used.

  As the abrasive particles, a group consisting of silica particles and alumina particles from the viewpoint of good dispersion stability in the CMP polishing liquid and a small number of abrasive scratches (sometimes referred to as “scratch”) generated by CMP. At least one selected from the group consisting of colloidal silica and colloidal alumina is more preferable, and colloidal silica is more preferable.

  The average particle diameter of the abrasive particles is preferably 20 nm or more, more preferably 30 nm or more, still more preferably 40 nm or more, from the viewpoint of obtaining a better polishing rate of the metal-containing part. The average particle size of the abrasive particles is preferably 150 nm or less, more preferably 130 nm or less, and still more preferably 100 nm or less, from the viewpoint of suppressing polishing scratches. In this embodiment, the average particle size of the abrasive particles is the average secondary particle size.

The particle size of the abrasive particles can be measured with a light diffraction scattering type particle size distribution meter (for example, “COULTER N4SD” manufactured by COULTER Electronics) using an aqueous dispersion prepared by appropriately diluting the CMP polishing liquid with water. . For example, the measurement conditions of a light diffraction / scattering particle size distribution meter are: measurement temperature 20 ° C., solvent refractive index 1.333 (corresponding to the refractive index of water), particle refractive index Unknown (setting), solvent viscosity 1.005 mPa · s ( Equivalent to the viscosity of water), Run Time 200 sec, laser incident angle 90 °. Intensity (equivalent to scattering intensity, turbidity) is adjusted to fall within the range of 5 × 10 ⁴ to 4 × 10 ⁵ , and when it is higher than 4 × 10 ⁵ , the CMP polishing liquid is diluted with water. After obtaining an aqueous dispersion, measurement is performed.

  The content of the abrasive particles is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, more preferably in the total mass of the polishing slurry for CMP from the viewpoint of obtaining a better polishing rate of the metal-containing part. Preferably it is 0.5 mass% or more. Further, the content of the abrasive particles is preferably 4.0% by mass or less, more preferably 4.0% by mass or less, in the total mass of the polishing slurry for CMP, from the viewpoint of maintaining good dispersion stability of the abrasive particles and suppressing the generation of abrasive scratches. Is 3.5% by mass or less, more preferably 3.0% by mass or less.

(Metal anticorrosive)
The CMP polishing liquid contains a metal anticorrosive. When the polishing liquid for CMP contains a metal anticorrosive, etching of the cobalt-containing part can be effectively suppressed while maintaining a good polishing rate of the cobalt-containing part.

  The metal anticorrosive agent preferably contains a triazole (triazole compound) having a triazole skeleton from the viewpoint of further suppressing etching of the cobalt-containing part while maintaining a good polishing rate of the cobalt-containing part.

  Specific examples of triazoles include 1,2,3-triazole; 1,2,4-triazole; 3-amino-1,2,4-triazole; benzotriazole, 1- Hydroxybenzotriazole, 1-hydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxybenzotriazole, 5- And benzotriazoles (benzotriazole compounds) such as methylbenzotriazole.

  The content of the metal anticorrosive is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably, in the total mass of the polishing slurry for CMP, from the viewpoint of further suppressing corrosion of the cobalt-containing part. Is 0.02 mass% or more. In addition, the content of the metal anticorrosive is preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably from the total mass of the polishing slurry for CMP from the viewpoint of obtaining a better polishing rate of the cobalt-containing part. Is 1% by mass or less.

(Organic acids)
The CMP polishing liquid may further contain organic acids. Organic acids have the effect of further improving the polishing rate of metal-containing parts (such as conductive substance parts such as cobalt-containing parts). Examples of organic acids include organic acids, organic acid salts, organic acid anhydrides, and organic acid esters. The organic acids can be used singly or in combination of two or more.

  Among organic acids, phthalic acids are preferable from the viewpoint of obtaining a good polishing rate for the cobalt-containing part and further suppressing corrosion of the cobalt-containing part. By using phthalic acids, it is possible to obtain a better polishing rate for the cobalt-containing portion and to further suppress corrosion. Examples of phthalic acids include phthalic acid, phthalic acid salts, phthalic acid anhydrides, and phthalic acid esters, which may or may not have a substituent. Good.

  Examples of the phthalic acids include phthalic acid; alkylphthalic acid such as 3-methylphthalic acid and 4-methylphthalic acid; aminophthalic acid such as 3-aminophthalic acid and 4-aminophthalic acid; 3-nitrophthalic acid, 4-nitrophthalic acid and the like. Nitrophthalic acid; salts thereof; anhydrides thereof; esters thereof. Among these, phthalic acid (methylphthalic acid) having a methyl group as a substituent is preferable, at least one selected from the group consisting of 3-methylphthalic acid and 4-methylphthalic acid is more preferable, and 4-methylphthalic acid is still more preferable. Examples of the salt include salts with alkali metals such as sodium and potassium, salts with alkaline earth metals such as magnesium and calcium, and ammonium salts. As organic acids other than phthalic acids, esters (excluding carbonates and lactones) such as ethyl acetate and ethyl lactate can be used.

  In the case where the CMP polishing liquid contains organic acids, the content thereof is preferably 0.001% by mass or more, more preferably in the total mass of the CMP polishing liquid, from the viewpoint of further suppressing the corrosion of the cobalt-containing part. It is 0.01 mass% or more, More preferably, it is 0.02 mass% or more. Further, the content of the organic acids is preferably 5% by mass or less, more preferably 3% by mass or less, more preferably 3% by mass or less in the total mass of the polishing slurry for CMP from the viewpoint of obtaining a better polishing rate of the cobalt-containing part. 1% by mass or less.

(Metal oxidizer)
The CMP polishing liquid may contain a metal oxidizing agent. The metal oxidizing agent is not particularly limited, and examples thereof include hydrogen peroxide, peroxosulfate, nitric acid, potassium periodate, hypochlorous acid, and ozone. As the metal oxidizing agent, hydrogen peroxide is preferable from the viewpoint of further improving the polishing rate of the metal-containing portion. A metal oxidizing agent can be used individually by 1 type or in mixture of 2 or more types.

  When the polishing slurry for CMP contains a metal oxidizer, the content is preferably 0.01% by mass or more in the total mass of the polishing slurry for CMP from the viewpoint of obtaining a better polishing rate of the cobalt-containing part. 0.02 mass% or more is more preferable, and 0.05 mass% or more is still more preferable. Further, the content of the metal oxidant is preferably 3% by mass or less, more preferably 1.5% by mass or less, and still more preferably 1% by mass or less from the viewpoint of preventing the surface to be polished from being rough.

(Organic solvent)
The polishing liquid for CMP may further contain an organic solvent (excluding compounds corresponding to organic acids). When the CMP polishing liquid contains an organic solvent, wettability of the CMP polishing liquid with respect to a metal-containing part (for example, a metal-containing part provided in the vicinity of the cobalt-containing part) can be improved. Although there is no restriction | limiting in particular as an organic solvent, What can mix with water is preferable and what melt | dissolves 0.1g or more with respect to 100g of water at 25 degreeC is more preferable. An organic solvent can be used individually by 1 type or in mixture of 2 or more types.

  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 ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (glycol derivatives) Except); methanol, ethanol, propanol, Alcohols (monoalcohols) such as butanol, n-pentanol, n-hexanol, isopropanol, 3-methoxy-3-methyl-1-butanol; ketones such as acetone and methyl ethyl ketone; dimethylformamide, N-methylpyrrolidone Amides; and the like; and sulfolanes such as sulfolane.

  The organic solvent may be a derivative of glycols. Examples of glycol derivatives include ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether. , Diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monopropyl ether, diethylene glycol monopropyl ether, triethylene glycol Glycol monoethers such as monopropyl ether, tripropylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether; ethylene Glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ethyl ether, tripropylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, diethyl Glycol diethyl ether, dipropylene glycol diethyl ether, triethylene glycol diethyl ether, tripropylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol dipropyl ether, diethylene glycol dipropyl ether, dipropylene glycol dipropyl ether, triethylene glycol Examples include glycol ethers such as dipropyl ether, tripropylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, triethylene glycol dibutyl ether, and tripropylene glycol dibutyl ether. Et It is.

  The organic solvent is preferably at least one selected from the group consisting of glycols, glycol derivatives, alcohols, and carbonates, and more preferably alcohols.

  When the CMP polishing liquid contains an organic solvent, the content is preferably 0.1% by mass or more in the total mass of the CMP polishing liquid from the viewpoint of obtaining better wettability with respect to the metal-containing portion. 0.2 mass% or more is more preferable, and 0.5 mass% or more is still more preferable. Further, the content of the organic solvent is preferably 95% by mass or less and more preferably 50% by mass or less in the total mass of the polishing slurry for CMP from the viewpoint of preventing the possibility of ignition and safely implementing the manufacturing process. 10 mass% or less is further more preferable, 5 mass% or less is especially preferable, and 3 mass% or less is very preferable.

(water)
The CMP polishing liquid contains water. Water is not particularly limited, but pure water can be preferably used. Water may be blended as the remainder, and the content is not particularly limited.

(PH of polishing liquid for CMP)
The pH of the CMP polishing liquid is preferably 4.0 or less. When pH is 4.0 or less, it is further excellent in the grinding | polishing rate of a metal containing part (electroconductive substance parts, such as a cobalt containing part). From the same viewpoint, the pH is preferably 3.8 or less, more preferably 3.6 or less, and even more preferably 3.5 or less. In addition, the pH of the polishing slurry for CMP is 2 from the viewpoint of further suppressing the corrosion of the metal-containing part (such as a conductive substance part such as a cobalt-containing part) and the difficulty of handling due to strong acidity. 0.0 or more is preferable, 2.5 or more is more preferable, 2.8 or more is further preferable, and 3.0 or more is particularly preferable.

  The pH can be adjusted by adding an acid component. It can also be adjusted by adding alkali components such as ammonia, sodium hydroxide, tetramethylammonium hydroxide (TMAH).

  The pH of the polishing slurry for CMP can be measured with a pH meter (for example, “Model number: PHL-40” manufactured by Electrochemical Instruments Co., Ltd.). After three-point calibration using standard buffer (phthalate pH buffer pH: 4.01, neutral phosphate pH buffer pH: 6.86, borate pH buffer pH: 9.18) Then, the value is measured after the electrode is placed in the CMP polishing liquid and stabilized for 3 minutes or more. At this time, the temperature of the standard buffer solution and the polishing slurry for CMP are both 25 ° C.

  The CMP polishing liquid can be applied, for example, to the formation of a wiring pattern in a semiconductor device. As a metal containing part, the electroconductive substance part mentioned later is mentioned, for example. Furthermore, the insulating material portion described later may be included in the surface to be polished. The materials constituting the cobalt-containing part and the metal-containing part will be described later.

(Two-component polishing liquid)
In the CMP polishing liquid according to the present embodiment, the constituents of the polishing liquid may be stored separately in the slurry and the additive liquid so that the slurry and the additive liquid are mixed to form the polishing liquid. It can be obtained by mixing two liquids divided into a slurry (first liquid) containing abrasive particles and an additive liquid (second liquid) containing at least a methacrylic acid polymer. By doing so, it is possible to avoid the problem of stability of the abrasive particles which occurs when a large amount of methacrylic acid polymer is added. When dividing into two liquids, a methacrylic acid polymer may be contained on the slurry side. However, in this case, the content of the methacrylic acid polymer in the slurry is preferably in a range that does not impair the dispersibility of the abrasive particles.

<Polishing method>
The polishing method according to the present embodiment includes an insulating material part, a cobalt-containing part, and a titanium-containing part that bonds the insulating material part and the cobalt-containing part using the CMP polishing liquid according to the present embodiment. And a polishing step of polishing at least a part of the cobalt-containing portion by polishing the surface to be polished of the substrate having the cobalt-containing portion exposed on the surface to be polished. The surface to be polished may have a metal-containing portion containing a metal other than cobalt. The polishing method according to the present embodiment uses the polishing liquid for CMP according to the present embodiment, and the cobalt-containing portion of the surface to be polished having at least a cobalt-containing portion and a metal-containing portion containing a metal other than cobalt. A polishing method of polishing and removing at least a part of the substrate may be used. The polishing method according to the present embodiment uses a polishing liquid for CMP according to the present embodiment to have a cobalt-containing portion and a cobalt on a surface to be polished that does not have a copper-containing portion containing copper as a main component. A polishing method in which at least a part of the containing part is polished and removed may be used.

  The polishing method according to the present embodiment is preferably a polishing method in which an excess portion of the cobalt-containing portion is polished and removed from a substrate having a cobalt-containing portion and a metal-containing portion formed on at least one surface. More specifically, the polishing method according to the present embodiment is for CMP according to the present embodiment between the surface of the substrate on which the cobalt-containing portion and the metal-containing portion are formed and the polishing pad on the polishing surface plate. A polishing method in which at least a part of the cobalt-containing portion is polished and removed by relatively moving the substrate and the polishing surface plate while the substrate is pressed against the polishing pad while supplying the polishing liquid may be used. .

  The polishing method according to this embodiment can be applied to a series of steps for forming a wiring layer in a semiconductor device. In this case, the polishing method according to the present embodiment includes, for example, an insulating material portion having irregularities (concave and convex portions) on the surface, a liner portion that covers the insulating material portion along the irregularities, and the concave and convex portions of the irregularities. Preparing a substrate having a metal-containing portion (conductive material portion or the like) that covers the liner portion by filling the liner portion, polishing the metal-containing portion to expose the liner portion on the convex and concave portions A first polishing step and a second polishing step of polishing and removing the liner portion exposed in the first polishing step using the CMP polishing liquid according to the present embodiment are provided. The liner portion may be composed of a plurality of layers. For example, the liner portion includes a first liner portion that covers the insulating material portion along the unevenness of the insulating material portion, and a second liner that covers the first liner portion along the shape of the first liner portion. And may have a part.

  In the polishing method according to the first embodiment, the liner part is a titanium-containing part, and the metal-containing part is a cobalt-containing part. In the polishing method according to the second embodiment, the liner part is composed of at least two layers, the first liner part is a cobalt-containing part, the second liner part is a titanium-containing part, and the metal-containing part Is a metal containing part containing metals other than cobalt.

  Hereinafter, an example of the polishing method will be described with reference to FIGS. 1 and 2. However, the use of the polishing method is not limited to the following steps. FIG. 1 is a schematic cross-sectional view showing a polishing method according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing a polishing method according to the second embodiment.

  A substrate 10a shown in FIG. 1 has a liner portion 12 as a titanium-containing portion and a metal-containing portion 13 as a cobalt-containing portion. The metal containing part 13 is a cobalt containing part formed by CVD method, for example. As shown in FIG. 1A, a substrate 10a before polishing is formed on a silicon substrate (not shown) along an insulating material part 11 having irregularities of a predetermined pattern and irregularities on the surface of the insulating material part 11. And a liner part (titanium-containing part) 12 covering the insulating material part 11 and a metal-containing part (cobalt-containing part) 13 formed on the liner part 12.

  A substrate 20a shown in FIG. 2 includes a cobalt-containing portion 22a and a titanium-containing portion 22b as the liner portion 22, and a metal-containing portion 23 as the conductive material portion. The cobalt containing part 22a is a cobalt containing part formed by CVD method, for example. The titanium-containing portion 22b is, for example, a single layer such as Ti or TiN, or a Ti / TiN laminate. As shown in FIG. 2A, the unpolished substrate 20 a is provided on a silicon substrate (not shown) along an insulating material part 21 having irregularities with a predetermined pattern and irregularities on the surface of the insulating material part 21. The titanium-containing portion 22b covering the insulating material portion 21, the cobalt-containing portion 22a covering the titanium-containing portion 22b, and the metal-containing portion 23 formed on the cobalt-containing portion 22a. The metal-containing part 23 may be a cobalt-containing part (for example, a cobalt-containing part formed by a PVD method), and contains a metal other than cobalt (such as a conductive material, for example, a metal different from a copper-based metal). A metal containing part may be sufficient.

  The to-be-polished surface of a board | substrate may be an aspect which does not have a copper containing part which contains copper as a main component, for example. For example, the polished surface of each substrate shown in FIG. 1 does not have a copper-containing portion. Moreover, the to-be-polished surface of each board | substrate shown in FIG. 2 does not have a copper containing part, when the metal containing part 23 does not contain a copper-type metal.

  Examples of the material forming the insulating material portions 11 and 21 include a silicon-based insulating material (insulator), an organic polymer-based insulating material (insulator), and the like. Silicon-based insulating materials include silica-based insulating materials such as organosilicate glass, silicon oxynitride and silsesquioxane hydride obtained from silicon dioxide, fluorosilicate glass, trimethylsilane, and dimethoxydimethylsilane as starting materials; silicon carbide A silicon nitride may be used. Examples of the organic polymer insulating material include wholly aromatic low dielectric constant insulating materials (insulators). Among these, silicon dioxide is particularly preferable.

  The insulating material portions 11 and 21 can be formed by, for example, a CVD (chemical vapor deposition) method, a spin coating method, a dip coating method, a spray method, or the like. Specific examples of the insulating material portions 11 and 21 include an interlayer insulating film in an LSI manufacturing process (particularly, a multilayer wiring forming process).

  The liner parts 12 and 22 prevent the constituent materials (conductive substances, etc.) of the metal-containing parts 13 and 23 from diffusing into the insulating material parts 11 and 21, and the insulating material parts 11 and 21 and the metal-containing parts. It is formed to improve the adhesion to the parts 13 and 23. Examples of the material used for forming the cobalt-containing portion include cobalt compounds such as cobalt, a cobalt alloy, a cobalt oxide, and a cobalt alloy oxide. Examples of the barrier metal used for forming the liner portions 12 and 22 include tantalum compounds such as tantalum, tantalum nitride, and tantalum alloys, titanium compounds such as titanium, titanium nitride, and titanium alloys, and tungsten compounds such as tungsten, tungsten nitride, and tungsten alloys. And ruthenium compounds such as ruthenium, ruthenium nitride and ruthenium alloys. The liner portions 12 and 22 may have, for example, a single layer structure made of one of these, or a laminated structure made of two or more kinds. That is, the liner parts 12 and 22 have at least one selected from the group consisting of a tantalum-containing part, a titanium-containing part, a tungsten-containing part, and a ruthenium-containing part. The liner portions 12 and 22 can be formed by, for example, vapor deposition, CVD (chemical vapor deposition), sputtering, or the like.

  The metal-containing portions 13 and 23 include cobalt, a cobalt alloy, a cobalt oxide, a cobalt-based metal such as a cobalt alloy oxide, a tungsten-based metal such as a tungsten alloy, silver, silver, Precious metals such as gold can be used. Among these, metals having cobalt as a main component such as cobalt, a cobalt alloy, an oxide of cobalt, and an oxide of cobalt alloy are preferable. The “metal having cobalt as a main component” refers to a metal having the largest cobalt content (mass). The metal containing parts 13 and 23 can be formed by, for example, a known sputtering method or plating method.

  The thickness of the insulating material portions 11 and 21 is preferably about 0.01 to 2.0 μm. As for the thickness of the liner part 12, and the thickness of the cobalt containing part 22a and the titanium containing part 22b, about 0.01-2.5 micrometers is preferable. As for the thickness of the metal containing parts 13 and 23, about 0.01-2.5 micrometers is preferable.

  In the first polishing step, from the state shown in FIG. 1 (a) to the state shown in FIG. 1 (b), or from the state shown in FIG. 2 (a) to the state shown in FIG. 2 (b). The metal-containing parts (conductive material parts) 13 and 23 are polished. In the first polishing step, the metal-containing portions 13 and 23 on the surface of the substrate 10a or the substrate 20a before polishing are, for example, for a metal (conductive material) having a sufficiently high polishing rate ratio of metal-containing portion / cobalt-containing portion. Polishing is performed by CMP using a polishing liquid for CMP. Thus, the substrate 10b having a conductor pattern (that is, a wiring pattern) in which the metal-containing portions 13 and 23 on the convex portions are removed, the cobalt-containing portions are exposed on the surface, and the metal-containing portions 13 and 23 are left in the concave portions. A substrate 20b is obtained. As the CMP polishing liquid for the metal (conductive substance) having a sufficiently high polishing rate ratio of metal-containing part / cobalt-containing part, for example, the CMP polishing liquid described in Japanese Patent No. 3337464 can be used. In the first polishing step, a part of the cobalt-containing portion on the convex portion may be polished together with the metal-containing portions 13 and 23.

  In the second polishing step, the cobalt exposed by the first polishing step from the state shown in FIG. 1B to the state shown in FIG. 1C using the CMP polishing liquid according to this embodiment. The containing part is polished, and the excess cobalt-containing part is removed.

  Further, as shown in FIG. 2, when the liner portion 22 has a cobalt-containing portion 22 a and a titanium-containing portion 22 b, in the second polishing step, the state shown in FIG. The cobalt-containing portion 22a and the titanium-containing portion 22b are polished until the state shown in FIG. 6), and the excess cobalt-containing portion 22a and the excess titanium-containing portion 22b are removed. At this time, the cobalt-containing portion 22a is polished by the CMP polishing liquid according to the present embodiment, and the polishing is terminated when the titanium-containing portion 22b is exposed. Separately, the CMP-containing polishing liquid for polishing the titanium-containing portion 22b is used. The titanium containing part 22b may be polished. Further, as a series of steps, the cobalt-containing portion 22a and the titanium-containing portion 22b may be polished with the CMP polishing liquid according to the present embodiment.

  The insulating material portions 11 and 21 under the convex liner portion (the liner portion (cobalt-containing portion) 12 in FIG. 1 or the cobalt-containing portion 22a and the titanium-containing portion 22b in FIG. 2) are all exposed, and the wiring pattern When the substrate 10c or the substrate 20c having a desired pattern in which the cross section of the liner portion is exposed at the boundary between the convex portion and the concave portion is left, the polishing is finished. To do. Furthermore, the metal-containing part embedded in the recess may be polished together with the liner part.

  In the second polishing step, a polishing liquid for CMP is supplied between the polishing pad and the substrate while pressing the substrate 10b or the substrate 20b on the polishing pad of the polishing platen with the surface to be polished facing the polishing pad. However, the surface to be polished is polished by relatively moving the polishing surface plate and the substrate 10b or the substrate 20b.

  As an apparatus used for polishing, a general polishing apparatus having a holder for holding a substrate to be polished, and a polishing platen connected to a motor whose rotation speed can be changed and a polishing pad attached thereto can be used. . As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation.

The polishing conditions are not particularly limited, but the rotation speed of the polishing surface plate is preferably a low rotation speed of 200 min ⁻¹ or less so that the substrate does not jump out. The pressure for pressing the substrate against the polishing pad is preferably 1 to 100 kPa, and more preferably 5 to 50 kPa in order to satisfy the in-surface uniformity of the polishing rate and the flatness of the pattern.

  During polishing, the CMP polishing liquid according to the present embodiment can be continuously supplied between the polishing pad and the surface to be polished by a pump or the like. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with a CMP polishing liquid. The substrate after polishing is preferably washed in running water and then dried after removing water droplets adhering to the substrate using spin drying or the like.

  In order to perform CMP with the surface state of the polishing pad always the same, it is preferable to perform a polishing pad conditioning step before polishing. For example, using a dresser with diamond particles, the polishing pad is conditioned with a liquid containing at least water. Subsequently, it is preferable to perform a substrate cleaning step after performing the polishing method according to the present embodiment.

  On the wiring pattern thus formed, a second-layer insulating material portion, a liner portion, and a metal-containing portion (conductive material portion) are further formed and then polished over the entire surface of the semiconductor substrate. A smooth surface can be obtained. By repeating this step a predetermined number, a semiconductor device having a desired number of wiring layers can be manufactured.

  The CMP polishing liquid according to this embodiment can be used not only for polishing a semiconductor substrate as described above but also for polishing a substrate such as a magnetic head.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these Examples, unless it deviates from the technical idea of this invention. For example, the type of polishing liquid for CMP and the blending ratio thereof may be other types and ratios than those described in this example, and the composition and structure of the polishing target are also described in this example. It may be a composition and structure other than the composition and structure.

<Synthesis of methacrylic acid polymer>
(Polymers 1-12)
Table 1 shows the molar ratio (mol%) of each monomer in the methacrylic acid polymer, the polymerization initiator used when synthesizing the methacrylic acid polymer, and the acid for dissolving the polymerization initiator. Water containing an acid shown in Table 1 was prepared as an aqueous solvent, and a polymerization initiator was dissolved therein. Subsequently, the monomers shown in Table 1 were polymerized in an aqueous solvent to obtain a methacrylic acid polymer.

The details of the polymerization initiator in Table 1 are as follows.
VA-061: 2,2′-azobis [2- (2-imidazolin-2-yl) propane] (manufactured by Wako Pure Chemical Industries, Ltd.)
VA-057: 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] (manufactured by Wako Pure Chemical Industries, Ltd.)

The weight average molecular weight of the methacrylic acid polymer was measured by gel permeation chromatography under the following measurement conditions. Standard polystyrene was used as a standard substance. The measurement results are shown in Table 1.
Column: Shodex Asahipak GS-520HQ + 620HQ manufactured by Showa Denko KK
Pump: Hitachi Ltd. L-71000
_{Eluent: 50mM-Na 2 HPO 4 aq} . / CH ₃ CN = 90/10
Flow rate: 0.6 mL / min
Detector: L-3300 differential refractometer manufactured by Hitachi, Ltd. Data processing: D-2520 GPC integrator manufactured by Hitachi, Ltd. Sample concentration: 10 mg / mL
Injection volume: 5 μL

<Preparation of CMP polishing liquid>
A polishing liquid for CMP was prepared by the following method using each component shown in Table 2.

(Examples 1-9 and Comparative Examples 1-5)
A methacrylic acid polymer (polymers 1 to 12) of the type shown in Table 2, abrasive particles, metal anticorrosive, metal oxidizer and organic solvent, and water are mixed to prepare each polishing liquid of Examples and Comparative Examples. did. In addition, colloidal silica (average secondary particle size 60 nm) was used as abrasive particles. The content of each component (standard: the total mass of the polishing slurry for CMP, the balance being water) was as follows. The content of the methacrylic acid polymer was 0.05% by mass. The content of abrasive particles (content of silica particles) was 1.0% by mass. The content of the metal anticorrosive was 0.1% by mass. The content of the metal oxidant (hydrogen peroxide content) was 0.07% by mass. The content of the organic solvent was 1.4% by mass.

<Measurement method of pH>
The pH of the CMP polishing liquid was measured according to the following.
Measurement temperature: 25 ° C
Measuring instrument: “PHL-40” manufactured by Electrochemical Instruments Co., Ltd.
Measurement method: standard buffer (phthalate pH buffer solution pH: 4.01 (25 ° C.), neutral phosphate pH buffer solution pH: 6.86 (25 ° C.), borate pH buffer solution pH: 9 After calibrating three points using .18 (25 ° C.), the electrode was placed in a CMP polishing liquid, and the value after 3 minutes had elapsed and stabilized was measured, and the results are shown in Table 2.

<Evaluation of etching amount for cobalt>
A blanket substrate (a) in which a cobalt layer having a thickness of 200 nm was formed on a silicon substrate having a diameter of 12 inches was prepared. The blanket substrate (a) was cut into 20 mm square chips to prepare evaluation chips (b).

Each of the evaluation chips (b) was put in a beaker containing 100 g of the polishing liquid, and immersed in a thermostatic bath at 60 ° C. for 1 min. The evaluation chip (b) after immersion was taken out and thoroughly washed with pure water, and then nitrogen gas was blown to remove the moisture on the chip to dry the chip. The resistance value of the evaluation chip (b) after drying was measured with a resistivity meter, and converted into the thickness of the cobalt layer after immersion by the following formula (1).
Thickness [nm] of cobalt layer after immersion = 104.5 × (resistance value [mΩ] / 1000 of evaluation chip (b)) − ^0.893 (1)

And the etching rate of the cobalt layer was calculated | required from following formula (2) from the thickness of the obtained cobalt layer after immersion, and the thickness of the cobalt layer before immersion.
Etching rate of cobalt layer (Co-ER) [nm / min] = (thickness of cobalt layer before immersion [nm] −thickness of cobalt layer after immersion [nm]) / 1 min (2)

  The etching rate of the cobalt layer was calculated | required about each polishing liquid obtained above. The results are shown in Table 2.

<Evaluation of cobalt polishing rate>
The polishing rate (Co-RR) [nm / min] when the blanket substrate (a) was polished and washed under the following conditions using each polishing liquid obtained above was determined. The results are shown in Table 2.

[Polishing conditions]
Polishing device: Polishing machine for single-sided metal film ("Reflexion LK" manufactured by Applied Materials)
Polishing pad: Polishing pad made of foamed polyurethane resin Surface plate rotation speed: 93 min ⁻¹
Polishing head rotation speed: 87 min ⁻¹
Polishing pressure: 10.3 kPa (1.5 psi)
Supply amount of polishing liquid for CMP: 300 mL / min
Polishing time: 0.5 min

[Cleaning of polished substrate]
After pressing a sponge brush (made of polyvinyl alcohol resin) onto the surface to be polished of the substrate polished above, the substrate to be polished and the sponge brush were rotated while supplying distilled water to the substrate to be cleaned, and washed for 1 min. . Next, after removing the sponge brush, distilled water was supplied to the surface to be polished of the substrate to be polished for 1 min. Finally, the substrate to be polished was rotated at a high speed to blow off distilled water and dry the substrate to be polished.

  As is apparent from Table 2, in Examples 1 to 9, the CMP polishing liquid contains a specific methacrylic acid polymer, so that the etching rate of cobalt is remarkably suppressed even at 60 ° C. It was found that the cobalt layer can be polished at an appropriate polishing rate.

  According to the polishing slurry for CMP and the manufacturing method thereof and the polishing method according to the present embodiment, while maintaining a good polishing rate of the cobalt-containing portion as compared with the case of using the conventional polishing slurry for CMP, Etching of the cobalt-containing portion can be suppressed.

  DESCRIPTION OF SYMBOLS 1, 11, 21 ... Insulating material part, 2, 12, 22 ... Liner part, 3, 23 ... Conductive substance part, 10a, 10b, 10c, 20a, 20b, 20c ... Board | substrate, 13, 23 ... Metal containing part, 22a ... Cobalt-containing part, 22b ... Titanium-containing part.

Claims (16)

The to-be-polished surface of a substrate having an insulating material portion, a cobalt-containing portion, and a titanium-containing portion that bonds the insulating material portion and the cobalt-containing portion, and the cobalt-containing portion is exposed on the to-be-polished surface CMP polishing liquid for polishing
A methacrylic acid-based polymer having a structural unit derived from the reaction of a monomer component containing at least methacrylic acid under a condition in which no inorganic acid is present;
Abrasive particles,
Metal anticorrosive,
Polishing liquid for CMP containing water.   The polishing liquid for CMP according to claim 1, wherein the surface to be polished of the substrate does not have a copper-containing portion containing copper as a main component.   The polishing slurry for CMP according to claim 1 or 2, wherein the metal anticorrosive contains a triazole.   The polishing for CMP according to any one of claims 1 to 3, wherein the abrasive particles include at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. liquid.   The polishing liquid for CMP as described in any one of Claims 1-4 which further contains a metal oxidizing agent.   The polishing slurry for CMP according to any one of claims 1 to 5, further comprising an organic solvent. The to-be-polished surface of a substrate having an insulating material portion, a cobalt-containing portion, and a titanium-containing portion that bonds the insulating material portion and the cobalt-containing portion, and the cobalt-containing portion is exposed on the to-be-polished surface A method for producing a polishing slurry for CMP for polishing
Comprising a step of polymerizing a monomer component containing at least methacrylic acid to obtain a methacrylic acid polymer in a solution containing an aqueous solvent and a polymerization initiator and not containing an inorganic acid,
The method for producing a polishing slurry for CMP, wherein the polishing slurry for CMP contains the methacrylic acid polymer, abrasive particles, a metal anticorrosive, and water.   The method for producing a polishing slurry for CMP according to claim 7, wherein the surface to be polished of the substrate does not have a copper-containing portion containing copper as a main component.   The method for producing a polishing slurry for CMP according to claim 7 or 8, wherein the aqueous solvent comprises water.   The manufacturing method of the polishing liquid for CMP of Claim 7 or 8 with which the said aqueous solvent contains organic acids.   The manufacturing method of the polishing liquid for CMP as described in any one of Claims 7-10 in which the said metal corrosion inhibitor contains triazoles.   The polishing for CMP according to any one of claims 7 to 11, wherein the abrasive particles include at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. Liquid manufacturing method.   The method for producing a polishing slurry for CMP according to any one of claims 7 to 12, wherein the polishing slurry for CMP further contains a metal oxidizing agent.   The method for producing a polishing slurry for CMP according to any one of claims 7 to 13, wherein the polishing slurry for CMP further contains an organic solvent.   The polishing slurry for CMP according to any one of claims 1 to 6 or the polishing slurry for CMP obtained by the method for producing the polishing slurry for CMP according to any one of claims 7 to 14 is used. A polishing method comprising: polishing the surface to be polished of the substrate to remove at least a part of the cobalt-containing portion.   The polishing method according to claim 15, wherein the surface to be polished has a metal-containing portion containing a metal other than cobalt.

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