Grinding slurry and grinding method

Abstract

A polishing slurry for polishing surfaces containing tungsten material, the slurry containing abrasive grains, an iron-containing compound, and an oxidizing agent, wherein the abrasive grains comprise silica particles, the average particle size of the abrasive grains is 40–140 nm, and the silanol group density of the silica particles is 8.0 particles / nm. 2 The following is a grinding method that uses a grinding fluid to grind a surface containing tungsten material.

Description

Technical Field

[0001] This invention relates to a grinding fluid, a grinding method, etc. Background Technology

[0002] In recent years, with the increasing integration or performance of semiconductor integrated circuits (hereinafter referred to as "LSI"), new microfabrication technologies have been developed. Chemical mechanical polishing (hereinafter referred to as "CMP") is one such technology, which is frequently used in LSI manufacturing processes (especially in the planarization of interlayer insulating films, metal plug formation, and embedded wiring formation in multilayer wiring formation processes) (see, for example, Patent Document 1 below).

[0003] As a method for forming embedded wiring using CMP, the damascene method is known. In the damascene method, for example, first, irregularities are formed on the surface of an insulating component (a component containing an insulating material such as silicon oxide), then a blocking component following the shape of the insulating component surface is formed. Next, metal material (e.g., wiring metal) is deposited onto the blocking component in a recessed (groove) manner to obtain a metal component, thereby obtaining a substrate (the workpiece to be polished). Then, after removing unwanted metal components except for the recesses, the blocking components located on the protrusions of the insulating component are removed by CMP, thereby forming the embedded wiring.

[0004] In recent years, tungsten and tungsten alloys have begun to be used as metallic materials. An example of a method for forming tungsten material wiring using an inlay technique is shown below. Figure 1 .like Figure 1 As shown in (a), the substrate (body to be ground) 10 includes: an insulating member 1 with uneven surfaces; a blocking member (a member containing blocking material) 2 that follows the shape of the surface of the insulating member 1; and a tungsten member (a member containing tungsten material) 3 that covers the entire blocking member 2 by means of embedding into a recess. The grinding method of the substrate 10 sequentially includes: a first grinding step (coarse grinding step). Figure 1 (a)~ Figure 1 (b) Grinding the tungsten component 3 until the blocking component 2 is exposed; second grinding process ( Figure 1 (b)~ Figure 1 (c) Grinding the blocking component 2 and the tungsten component 3 until the insulating component 1 is exposed; and the third grinding process (fine grinding process) grinding the insulating component 1, the blocking component 2 and the tungsten component 3 to eliminate the step difference generated in the first and second grinding processes and adjust to an appropriate thickness.

[0005] As a polishing slurry for polishing tungsten materials, for example, Patent Document 2 disclosed below discloses a polishing slurry containing colloidal silica, inorganic acid, ferric nitrate, etc.

[0006] Previous technical documents

[0007] Patent documents

[0008] Patent Document 1: US Patent No. 4,944,836

[0009] Patent Document 2: Japanese Patent Application Publication No. 2009-206148 Summary of the Invention

[0010] The technical problem to be solved by the invention

[0011] However, from the perspective of improving the efficiency of the wiring formation process based on the inlay method, the grinding fluid used for grinding tungsten materials needs to grind tungsten materials at a better grinding speed.

[0012] One object of the present invention is to provide a grinding slurry capable of grinding tungsten materials at an excellent grinding speed. Another object of the present invention is to provide a grinding method using this grinding slurry.

[0013] means for solving technical problems

[0014] The inventors have discovered that by using a grinding fluid containing specific abrasive particles, an iron-containing compound, and an oxidant, tungsten materials can be ground at an excellent grinding speed.

[0015] One aspect of the present invention provides a polishing slurry for polishing a surface containing tungsten material. The slurry contains abrasive particles, an iron-containing compound, and an oxidizing agent. The abrasive particles comprise silica particles with an average particle size of 40–140 nm and a silanol group density of 8.0 particles / nm. 2 the following.

[0016] Another aspect of the present invention provides a grinding method for grinding a surface containing tungsten material using the above-described grinding fluid.

[0017] The present invention relates in several aspects to the following <1> to <15>.

[0018] <1> An abrasive slurry for abrading a surface containing tungsten material, the abrasive slurry containing abrasive grains, an iron-containing compound, and an oxidant, wherein the abrasive grains contain silica particles, the average particle size of the abrasive grains is 40-140 nm, and the silanol group density of the silica particles is 8.0 particles / nm. 2 the following.

[0019] <2> According to the polishing slurry described in <1>, the average particle size of the abrasive grains is 40-85 nm.

[0020] <3> According to the polishing slurry described in <1> or <2>, the silanol group density of the silica particles is 2.5 groups / nm.2 the following.

[0021] <4> The polishing slurry according to any one of <1> to <3>, wherein the silanol group density of the silica particles is less than 2.0 groups / nm. 2 Based on the total mass of the grinding slurry, the aluminum atom content is less than 0.000006% by mass.

[0022] <5> The polishing slurry according to any one of <1> to <4>, wherein the zeta potential of the silica particles in the polishing slurry exceeds -10 mV, and the content of aluminum atoms is less than 0.000006 by mass based on the total mass of the polishing slurry.

[0023] <6> The grinding fluid according to any one of <1> to <5>, wherein the iron-containing compound comprises at least one selected from the group consisting of ferric nitrate and its hydrates.

[0024] <7> The grinding fluid according to any one of <1> to <6>, wherein, based on the total mass of the grinding fluid, the content of the iron-containing compound is 0.0001 to 0.1% by mass.

[0025] <8> The grinding fluid according to any one of <1> to <7>, wherein the oxidant comprises hydrogen peroxide.

[0026] <9> The grinding fluid according to any one of <1> to <8> further contains organic acid components.

[0027] <10> The grinding fluid according to <9>, wherein the organic acid component, as an organic acid component without carbon-carbon unsaturated bonds, comprises at least one selected from the group consisting of divalent organic acid components and trivalent organic acid components.

[0028] <11> The grinding fluid according to <9> or <10>, wherein the organic acid component comprises at least one selected from the group consisting of malonic acid, succinic acid, adipic acid, glutaric acid, malic acid, citric acid and their salts.

[0029] <12> The grinding fluid according to any one of <1> to <11> has a pH of 2.0 to 4.0.

[0030] <13> The grinding fluid according to any one of <1> to <12> has a pH of 2.5 to 3.5.

[0031] <14> A grinding method in which a grinding fluid comprising any one of <1> to <13> is used to grind a surface containing tungsten material.

[0032] Based on this grinding fluid and grinding method, tungsten materials can be ground at an excellent grinding speed.

[0033] Invention Effects

[0034] According to one aspect of the present invention, a grinding slurry capable of grinding tungsten materials at an excellent grinding speed can be provided. According to another aspect of the present invention, a grinding method using such a grinding slurry can be provided. Attached Figure Description

[0035] Figure 1 This is a schematic cross-sectional view used to illustrate the method of forming wiring in tungsten materials. Detailed Implementation

[0036] The embodiments of the present invention will now be described. However, the present invention is not limited to the following embodiments and can be implemented with various modifications within its scope.

[0037] <Definition>

[0038] In this specification, "grinding speed" refers to the speed at which the material being ground is removed by grinding (e.g., the reduction in the thickness of the material being ground per hour; Removal Rate). "Abrasive grain" refers to a collection of multiple particles, but for convenience, sometimes a single particle constituting an abrasive grain is referred to as an abrasive grain. The term "process" includes not only independent processes but also processes that achieve the desired effect of the process, even if they cannot be clearly distinguished from other processes. Regarding the term "film," when viewed in a top view, it includes not only the structure of a shape formed over the entire surface but also the structure of a shape formed in a portion. Numerical ranges indicated by "~" represent the ranges included by treating the values ​​before and after "~" as minimum and maximum values, respectively. "Above A" in a numerical range refers to A and the range exceeding A. "Below A" in a numerical range refers to A and the range less than A. Within the numerical ranges described in stages in this specification, the upper or lower limit of a particular stage's numerical range can be arbitrarily combined with the upper or lower limits of the numerical ranges of other stages. Within the numerical ranges described in this specification, the upper or lower limit of the numerical range can be replaced with the values ​​shown in the embodiments. "A or B" may include either A or B, or both. Unless otherwise specified, the materials illustrated in this specification can be used alone or in combination of two or more. In the case where multiple substances corresponding to each component are present in the composition, unless otherwise specified, the content of each component in the composition refers to the total amount of the multiple substances present in the composition.

[0039] <Grinding fluid>

[0040] The polishing slurry of this embodiment is a polishing slurry (polishing slurry for tungsten materials) used for polishing surfaces containing tungsten materials. "Tungsten material" refers to a material containing 50 moles or more of tungsten, and examples include tungsten (monomer), tungsten alloys, and tungsten compounds (tungsten oxide, tungsten silicide, tungsten nitride, etc.). The polishing slurry of this embodiment can be used as a CMP polishing slurry.

[0041] The polishing slurry involved in this embodiment contains abrasive particles, an iron-containing compound, and an oxidizing agent. The polishing slurry in this embodiment contains silica particles as abrasive particles, with an average particle size of 40–140 nm and a silanol group density of 8.0 particles / nm. 2 the following.

[0042] According to the polishing slurry of this embodiment, tungsten materials can be polished at an excellent polishing speed. The inventors speculate the following reasons for achieving this effect. However, the reasons are not limited to the following. Specifically, it is believed that when the density of silanol groups (Si-OH) in the silica particles in the polishing slurry containing silica particles as abrasives is below the aforementioned content, the density of silanol groups inside the silica particles is also low. In this case, the density of siloxane bonds (Si-O-Si) is higher than the density of silanol groups inside the silica particles, resulting in a sufficiently well-formed mesh structure based on siloxane bonds. Therefore, the hardness (rigidity) of the silica particles is excellent, thereby improving the mechanical (physical) action of the abrasives. Furthermore, if the average particle size of the abrasives is within the aforementioned range, both the physical polishing ability of each particle and the number of particles per unit area of ​​the polished surface can be appropriately balanced, thus improving the mechanical action of the abrasives. Furthermore, it is believed that by including iron-containing compounds and oxidants in the grinding fluid in addition to abrasive grains, the mechanical action of the abrasive grains and the chemical action of the grinding fluid can be effectively obtained, thus enabling the grinding of tungsten materials at an excellent grinding speed.

[0043] According to the polishing slurry described in this embodiment, in the evaluation method of the following embodiments, the polishing speed of the tungsten material can, for example, reach 350 nm / min or higher. The polishing speed of the tungsten material can be 370 nm / min or higher, 380 nm / min or higher, 390 nm / min or higher, 400 nm / min or higher, or 410 nm / min or higher.

[0044] The polishing slurry of this embodiment can also be used for polishing insulating materials (e.g., silicon oxide). According to the polishing slurry of this embodiment, for example in the evaluation method of the following embodiment, the polishing speed for silicon oxide can reach 80 nm / min or higher. The polishing speed for silicon oxide can be 90 nm / min or higher, 110 nm / min or higher, 130 nm / min or higher, 150 nm / min or higher, 170 nm / min or higher, 190 nm / min or higher, 210 nm / min or higher, or 230 nm / min or higher. In the first polishing step of the polishing method (wireforming based on damascene method) comprising the first polishing step (rough polishing step), the second polishing step, and the third polishing step (fine polishing step), it is sufficient to achieve an excellent polishing speed for tungsten materials. In contrast, in the third polishing step, excellent polishing speeds are required for both tungsten materials and insulating materials. In this regard, the polishing slurry according to this embodiment can achieve excellent polishing speed for both tungsten materials and insulating materials. Therefore, the first, second and third polishing processes can be performed with a single polishing slurry, thereby suppressing the complexity of the process and the increase in cost caused by using multiple polishing slurries in the wiring formation using the inlay method.

[0045] The polishing slurry according to this embodiment can selectively polish tungsten materials (e.g., tungsten) against insulating materials (e.g., silicon oxide). According to the polishing slurry according to this embodiment, for example in the evaluation method of the embodiments described later, the polishing speed ratio of tungsten material to insulating material (polishing speed of tungsten material / polishing speed of insulating material) can be, for example, 0.1 or higher. The polishing speed ratio of tungsten material to insulating material can be 0.5 or higher, 1.0 or higher, 1.5 or higher, 2.0 or higher, 2.3 or higher, 2.7 or higher, 3.0 or higher, 3.4 or higher, 3.8 or higher, 3.9 or higher, 4.0 or higher, 4.1 or higher, 4.2 or higher, 4.3 or higher, or 4.4 or higher. The polishing speed ratio of tungsten material to insulating material can be 5.5 or lower, 5.0 or lower, 4.5 or lower, 4.0 or lower, or 3.5 or lower.

[0046] According to the grinding fluid of this embodiment, the grinding speed is more easily increased than conventional grinding grains when the content of abrasive grains is equal. Therefore, it is possible to reduce the content of abrasive grains while obtaining a sufficient grinding speed, and avoid the cost increase caused by increasing the content of abrasive grains in order to increase the grinding speed.

[0047] According to this embodiment, an polishing slurry can be provided for use in polishing surfaces containing tungsten material. The polishing slurry according to this embodiment can be used to polish surfaces containing both tungsten material and insulating material. According to this embodiment, an polishing slurry can be provided for use in polishing surfaces containing both tungsten material and insulating material. According to this embodiment, an polishing slurry can be provided for use in polishing during the wiring formation process of semiconductor devices.

[0048] (Abrasive grains)

[0049] The polishing slurry involved in this embodiment contains abrasive particles containing silica particles (particles containing silica).

[0050] Examples of silica particles include amorphous silica, crystalline silica, fused silica, spherical silica, synthetic silica, hollow silica, and colloidal silica. From the perspectives of easily grinding tungsten and insulating materials at excellent grinding speeds, easily suppressing defects such as scratches on the ground surface, and easily improving the flatness of the ground surface, abrasive grains can contain colloidal silica.

[0051] The average particle size of the abrasive grains is 40–140 nm, as described above. From the viewpoint of easily grinding tungsten and insulating materials at excellent grinding speeds by increasing the physical grinding ability of each particle, the average particle size of the abrasive grains can be 45 nm or more, 50 nm or more, 55 nm or more, or 60 nm or more. From the viewpoint of balancing the grinding speed of tungsten and insulating materials, the average particle size of the abrasive grains can be 65 nm or more, 70 nm or more, exceeding 70 nm, 75 nm or more, 80 nm or more, exceeding 80 nm, 85 nm or more, 90 nm or more, 95 nm or more, 100 nm or more, exceeding 100 nm, 105 nm or more, or 110 nm or more. From the viewpoint of easily grinding tungsten and insulating materials at excellent grinding speeds by increasing the number of particles per unit area of ​​the ground surface, the average particle size of the abrasive grains can be 135 nm or less, 130 nm or less, 125 nm or less, 120 nm or less, 115 nm or less, or 110 nm or less. From the perspective of balancing the grinding speed of tungsten materials and insulating materials, the average particle size of abrasive grains can be below 105nm, below 100nm, below 95nm, below 90nm, less than 90nm, below 85nm, below 80nm, below 75nm, below 70nm, or below 65nm. From the above perspective, the average particle size of abrasive grains can be 40–135nm, 40–130nm, 40–120nm, 40–110nm, 40–100nm, 40–90nm, above 40nm and less than 90nm, 45–115nm, 50–120nm, 50–110nm, 55–110nm, 60–110nm, 60–100nm, above 60nm and less than 90nm, or 40–85nm.

[0052] From the perspective of easily grinding tungsten and insulating materials at excellent grinding speeds by improving the physical grinding ability of each particle, the average particle size of silica particles can be 40nm or higher, 45nm or higher, 50nm or higher, 55nm or higher, or 60nm or higher. From the perspective of balancing the grinding speed of tungsten and insulating materials, the average particle size of silica particles can be 65nm or higher, 70nm or higher, exceeding 70nm, 75nm or higher, 80nm or higher, exceeding 80nm, 85nm or higher, 90nm or higher, 95nm or higher, 100nm or higher, exceeding 100nm, 105nm or higher, or 110nm or higher. From the perspective of easily grinding tungsten and insulating materials at excellent grinding speeds by increasing the number of particles per unit area of ​​the ground surface, the average particle size of silica particles can be below 140nm, below 135nm, below 130nm, below 125nm, below 120nm, below 115nm, or below 110nm. From the perspective of balancing the grinding speed of tungsten materials and insulating materials, the average particle size of silica particles can be below 105nm, below 100nm, below 95nm, below 90nm, less than 90nm, below 85nm, below 80nm, below 75nm, below 70nm, or below 65nm. From the above perspective, the average particle size of silica particles can be 40–140nm, 40–135nm, 40–130nm, 40–120nm, 40–110nm, 40–100nm, 40–90nm, above 40nm and less than 90nm, 45–115nm, 50–120nm, 50–110nm, 55–110nm, 60–110nm, 60–100nm, above 60nm and less than 90nm, or 40–85nm.

[0053] The "average particle size" of abrasive particles (e.g., silica particles) refers to the secondary particle size measured by the following method. For example, a sample in which the abrasive particles are dispersed in water can be prepared, and the average particle size can be measured using a photodiffraction scattering particle size analyzer. For example, the average particle size can be measured using a COULTER N4SD manufactured by Coulter Electronics, Inc., within the range of measurement temperature: 20°C, solvent refractive index: 1.333 (water), particle refractive index: Unknown (set), solvent viscosity: 1.005 cp (water), run time: 200 seconds, laser incident angle: 90°, and intensity (equivalent to scattering intensity, turbidity): 5E+04 to 4E+05. If the intensity is higher than 4E+05, it can be diluted with water for measurement. Colloidal particles (e.g., colloidal silica) are typically obtained in a dispersed state in water, and therefore can be appropriately diluted to fall within the aforementioned scattering intensity range, thereby measuring the average particle size of the colloidal particles. The sample for dispersing abrasive particles in water can be prepared by dispersing the abrasive particles in water before they are mixed with other components for the preparation of the grinding slurry, or by dispersing abrasive particles recovered from the grinding slurry in water. The content used to measure the average particle size can be 0.5–2.0% by mass. Since the change in the average particle size of the abrasive particles before and after the preparation of the grinding slurry is small, the average particle size can be either the average particle size of the abrasive particles before the preparation of the grinding slurry or the average particle size of the abrasive particles recovered from the grinding slurry.

[0054] From the perspective of grinding tungsten materials at excellent grinding speeds, the silanol group density of silica particles (silicon dioxide particles per 1 nm) is... 2 The number of silanol groups in the surface area is 8.0 per nm. 2 From the perspective of easily grinding tungsten and insulating materials at excellent grinding speeds, the silanol group density of silica particles can be 7.0 particles / nm. 2 Below, 6.5 per nm 2 Below or 6.0 per nm 2 From the perspective of balancing the grinding speed of tungsten materials and insulating materials, the silanol group density of silica particles can be 5.5 particles / nm. 2 Below, 5.0 units / nm 2 Below, less than 5.0 per nm 2 4.8 per nm 2 Below, 4.5 per nm 2 Below, 4.0 units / nm 2 Below, less than 4.0 per nm 2 3.5 per nm 2 Below, 3.2 per nm2 Below, 3.0 units / nm 2 Below, less than 3.0 per nm 2 2.5 units / nm 2 Below, 2.2 units / nm 2 Below, 2.0 units / nm 2 Below, less than 2.0 per nm 2 1.9 per nm 2 Below, 1.8 per nm 2 Below, 1.7 per nm 2 Below or 1.6 per nm 2 The following is an example: The silanol group density of silica particles exceeds 0 per nm. 2 From the perspective of easily grinding tungsten and insulating materials at excellent grinding speeds, a speed of 0.1 particles / nm is achievable. 2 Above, 0.5 per nm 2 Above, 1.0 units / nm 2 Above, 1.2 units / nm 2 Above, 1.3 per nm 2 Above, 1.4 units / nm 2 Above, 1.5 units / nm 2 More than or 1.6 per nm 2 The above. Considering the balance between the grinding speeds of tungsten and insulating materials, the silanol group density of silica particles can be 1.7 groups / nm. 2 Above, 1.8 per nm 2 Above, 2.0 units / nm 2 Above, 2.2 units / nm 2 Above, 2.5 per nm 2 Above, 3.0 units / nm 2 Above, 3.2 units / nm 2 Above, 3.5 per nm 2 Above, 4.0 units / nm 2 Above, 4.5 per nm 2 Above, 4.8 per nm 2 Above, 5.0 units / nm 2 Above, 5.5 per nm 2 Above or 6.0 per nm 2 Based on the above considerations, the silanol group density of silica particles can exceed 0 per nm. 2 And 8.0 per nm 2 Below, more than 0 per nm 2 And 3.0 units / nm 2 Below, more than 0 per nm 2 And less than 2.0 per nm2 0.1–7.0 per nm 2 0.5–6.0 per nm 2 1.0–5.0 per nm 2 1.2–4.0 per nm 2 1.5–3.0 per nm 2 1.5–2.0 per nm 2 1.5 units / nm 2 More than or less than 2.0 units / nm 2 Or 1.6 to 1.8 pieces /

[0055] Silanol group density of silica particles (ρ [particles / nm)) 2 It can perform the following measurements and calculations.

[0056] [1] Weigh out a particle dispersion (colloidal silica, etc.) containing 15g of silica particles into a polybottle A.

[0057] [2] Add 0.1 mol / L hydrochloric acid aqueous solution to the particle dispersion of [1] to adjust the pH of the mixture A of silica particles and hydrochloric acid to 3.0 to 3.5. At this time, the amount of 0.1 mol / L hydrochloric acid aqueous solution added [g] is measured.

[0058] [3] Calculate the mass of mixture A.

[0059] [4] Weigh 1 / 10 of the mass of mixture A obtained in [3] into plastic bottle B.

[0060] [5] Add 30g of sodium chloride to mixture A in plastic bottle B and then add ultrapure water to obtain mixture B with a total amount of 150g.

[0061] [6] Add 0.1 mol / L sodium hydroxide aqueous solution to mixture B to adjust the pH, thereby obtaining mixture C with pH 4.0.

[0062] [7] Add 0.1 mol / L sodium hydroxide aqueous solution to mixture C until the pH becomes 9.0, and calculate the amount of sodium hydroxide (B [mol]) required for the pH to change from 4.0 to 9.0.

[0063] [8] The silanol group density of the silica particles was calculated by the following formula (1).

[0064] ρ=B·NA / (A·S BET )……(1)

[0065] In formula (1), NA [particles / mol] represents Avogadro's constant, A [g] represents the amount of silica particles, and S BET [m 2 [ / g] represents the BET specific surface area of ​​silica particles.

[0066] BET specific surface area S of silica particles BET The BET surface area method can be used for measurement. For example, regarding the BET surface area of ​​silica particles, a sample obtained by drying silica particles (colloidal silica, etc.) in a dryer at 150°C, then placing them in a measuring cell and degassing them under vacuum at 120°C for 60 minutes can be determined using a BET surface area measuring device via a single-point or multi-point method with adsorbed nitrogen. Specifically, a measuring sample obtained by pulverizing silica particles dried at 150°C into fine particles using a mortar (ceramic, 100 mL) can be placed in a measuring cell, and the BET surface area S of the silica particles can be measured using a BET surface area measuring device (e.g., manufactured by Yuasa Ionics Co., Ltd., product name: NOVE-1200). BET .

[0067] The silanol group density of silica particles can be obtained using silica particles before they are mixed with other components for the preparation of the polishing slurry, or silica particles recovered from the polishing slurry. Since the change in the silanol group density of silica particles before and after polishing slurry preparation is small, the silanol group density of silica particles can be either the silanol group density of silica particles before polishing slurry preparation or the silanol group density of silica particles recovered from the polishing slurry.

[0068] Detailed methods for calculating the silanol group density of silica particles are available, for example, in Analytical Chemistry, 1956, Vol. 28, No. 12, pp. 1981-1983 and Japanese Journal of Applied Physics, 2003, Vol. 42, pp. 4992-4997.

[0069] The abrasive particles in the polishing slurry according to this embodiment may include particles other than silica particles. Examples of constituent materials for particles other than silica particles include alumina, cerium oxide, zirconium oxide, cerium hydroxide, and resin particles.

[0070] The zeta potential (25°C) of abrasive particles (e.g., silica particles) in the polishing slurry can be either positive or negative. The zeta potential of the abrasive particles in the polishing slurry can be measured, for example, using a DT1202 (product name) manufactured by Nihon Rufuto Co., Ltd.

[0071] The zeta potential of the abrasive particles in the polishing slurry can be above -50mV, above -35mV, above -25mV, above -20mV, above -20mV, above -15mV, above -10mV, above -10mV, above -5.0mV, above -3.0mV, above -2.0mV, above -1.5mV, above -1.0mV, above -0.5mV, above -0.1mV, above 0mV, above 0mV, above 0mV, above 0.1mV, above 0.5mV, above 1.0mV, above 2.0mV, above 3.0mV, above 4.0mV, above 5.0mV, above 6.0mV, above 7.0mV, above 8.0mV, above 9.0mV, above 10mV, above 11mV, above 12mV, or above 13mV. The zeta potential of the abrasive grains in the polishing slurry can be below 50mV, below 30mV, below 20mV, below 15mV, below 13mV, below 12mV, below 11mV, below 10mV, below 9.0mV, below 8.0mV, below 7.0mV, below 6.0mV, below 5.0mV, less than 5.0mV, below 4.0mV, below 3.0mV, below 2.0mV, below 1.0mV, below 0.5mV, below 0.1mV, below 0mV, less than 0mV, below -0.1mV, below -0.5mV, or below -1.0mV. From the above perspective, the Zeta potential of abrasive particles in the polishing slurry can be -50 to 50 mV, -35 to 30 mV, -20 to 20 mV, exceeding -10 mV but below 50 mV, exceeding -10 mV but below 30 mV, exceeding -10 mV but below 20 mV, exceeding -10 mV but below 15 mV, -5.0 to 15 mV, or -1.0 to 13 mV or below.

[0072] From the perspective of easily grinding tungsten and insulating materials at excellent grinding speeds, based on the total mass of the abrasive grains (the total number of abrasive grains contained in the grinding slurry), the content of silica particles in the abrasive grains can be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more. The abrasive grains can be composed of silica particles (the abrasive grains contained in the grinding slurry are essentially 100% by mass silica particles).

[0073] Based on the total mass of the grinding slurry, the content of abrasive particles can be within the following range. From the viewpoint of easily grinding tungsten materials and insulating materials at excellent grinding speeds, the content of abrasive particles can be 0.01% by mass or more, 0.02% by mass or more, 0.05% by mass or more, 0.08% by mass or more, 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 1.0% by mass or more, exceeding 1.0% by mass, 1.2% by mass or more, 1.4% by mass or more, 1.5% by mass or more, 1.6% by mass or more, 1.8% by mass or more, or 2.0% by mass or more. From the perspectives of suppressing defects such as scratches on the ground surface after grinding and from the perspective of cost, the content of abrasive particles can be less than 20% by mass, less than 15% by mass, less than 10% by mass, less than 5.0% by mass, less than 5.0% by mass, less than 3.0% by mass, less than 3.0% by mass, less than 2.5% by mass, less than 2.2% by mass, less than 2.0% by mass, less than 2.0% by mass, less than 1.8% by mass, less than 1.6% by mass, less than 1.5% by mass, less than 1.4% by mass, or less than 1.2% by mass. From the above perspectives, the content of abrasive particles can be 0.01–20% by mass, 0.02–15% by mass, 0.05–10% by mass, 0.1–5.0% by mass, 0.2–3.0% by mass, or 0.3–2.0% by mass.

[0074] (Iron-containing compounds)

[0075] The polishing slurry involved in this embodiment contains an iron-containing compound (a compound containing iron components, excluding compounds that correspond to abrasive particles). It may contain an iron-containing compound containing iron ions, or it may contain an iron ion feeder that supplies iron ions to the polishing slurry as the iron-containing compound. The iron ions may be second iron ions (Fe2+). 2+ By including iron-containing compounds in the polishing slurry, i.e., the polishing slurry contains iron components (such as iron ions), tungsten materials can be polished at excellent polishing speeds.

[0076] As an iron-containing compound, iron salts can be used as iron ion suppliers. In the grinding slurry, the iron ion supplier can dissociate into iron ions and corresponding anions derived from the iron ion supplier. Iron-containing compounds (such as iron ion suppliers) sometimes also function as oxidizing agents; compounds that are equivalent to both iron-containing compounds and oxidizing agents are referred to as iron-containing compounds in this specification.

[0077] Iron-containing compounds, acting as iron ion donors, can contain either inorganic or organic iron salts. Examples of inorganic iron salts include ferric nitrate, ferric sulfate, ferric boride, ferric chloride, ferric bromide, ferric iodide, ferric phosphate, and ferric fluoride. Examples of organic iron salts include ferric triformate, ferric diformate, ferric acetate, ferric propionate, ferric oxalate, ferric malonate, ferric succinate, ferric malate, ferric glutarate, ferric tartrate, ferric lactate, and ferric citrate. Iron-containing compounds can contain ligands such as ammonia and water, or can be hydrates. Considering the ease of grinding tungsten materials at excellent grinding speeds, the ease of suppressing contamination of the grinding equipment and substrate, and the low cost and easy availability, iron-containing compounds can contain inorganic iron salts, at least one component selected from the group consisting of ferric nitrate and its hydrates, or ferric nitrate nonahydrate.

[0078] Based on the total mass of the grinding slurry, the content of iron compounds can be within the following ranges. From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, the content of iron compounds can be 0.0001% by mass or more, 0.0003% by mass or more, 0.0005% by mass or more, 0.0008% by mass or more, 0.001% by mass or more, 0.003% by mass or more, 0.005% by mass or more, 0.007% by mass or more, or 0.008% by mass or more. From the viewpoint of easily inhibiting the decomposition and deterioration of oxidants, thereby easily grinding tungsten materials at excellent grinding speeds, the content of iron compounds can be less than 1% by mass, less than 0.5% by mass, less than 0.1% by mass, less than 0.08% by mass, less than 0.05% by mass, less than 0.03% by mass, less than 0.01% by mass, less than 0.009% by mass, or less than 0.008% by mass. Based on the above considerations, the content of iron-containing compounds can be 0.0001–1% by mass, 0.0001–0.1% by mass, 0.0003–0.1% by mass, 0.0005–0.05% by mass, or 0.001–0.01% by mass.

[0079] Based on the total mass of the grinding slurry, the iron ion content can be within the following ranges. From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, the iron ion content can be 0.0001% by mass or more, 0.0003% by mass or more, 0.0005% by mass or more, 0.0008% by mass or more, 0.001% by mass or more, or 0.0011% by mass or more. From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, the iron ion content can be 0.1% by mass or less, 0.05% by mass or less, 0.01% by mass or less, 0.008% by mass or less, 0.005% by mass or less, 0.003% by mass or less, 0.0025% by mass or less, 0.002% by mass or less, 0.0015% by mass or less, or 0.0012% by mass or less. Based on the above considerations, the iron ion content can be 0.0001–0.1% by mass, 0.0003–0.05% by mass, 0.0005–0.01% by mass, or 0.001–0.005% by mass.

[0080] The mass ratio R1 (iron compound content / abrasive grain content) of the iron compound content to the abrasive grain content can be within the following ranges. From the viewpoint of easily grinding tungsten materials and insulating materials at excellent grinding speeds, the mass ratio R1 can be 0.0001 or higher, 0.0005 or higher, 0.001 or higher, 0.002 or higher, 0.003 or higher, or 0.004 or higher. From the viewpoint of balancing the grinding speeds of tungsten materials and insulating materials, the mass ratio R1 can be 0.005 or higher or 0.006 or higher. From the viewpoint of easily grinding tungsten materials and insulating materials at excellent grinding speeds, the mass ratio R1 can be 0.1 or lower, 0.05 or lower, 0.01 or lower, 0.008 or lower, or 0.007 or lower. From the viewpoint of balancing the grinding speeds of tungsten materials and insulating materials, the mass ratio R1 can be 0.006 or lower, 0.005 or lower, or 0.004 or lower. From the above perspective, the mass ratio R1 can be 0.0001–0.1, 0.0005–0.05, or 0.001–0.01.

[0081] (Oxidizing agent)

[0082] The polishing slurry involved in this embodiment contains an oxidizing agent (except for compounds equivalent to iron-containing compounds). By containing an oxidizing agent in the polishing slurry, the surface of the tungsten material is oxidized by the oxidizing agent, thus enabling the tungsten material to be polished at an excellent polishing speed.

[0083] Examples of oxidizing agents include hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, peroxydisulfuric acid, and ozonated water. Considering the ease of grinding tungsten materials at excellent grinding speeds, the ability to suppress contamination caused by alkali metals, alkaline earth metals, halides, etc., when the substrate is a silicon substrate containing integrated circuit components, and the minimal change in composition over time, hydrogen peroxide can be included as an oxidizing agent. The peroxydisulfuric acid content per 1L of grinding slurry can be less than 0.01 mol, less than 0.003 mol, less than 0.003 mol, less than 0.001 mol, or substantially 0 mol.

[0084] From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, the hydrogen peroxide content in the oxidant can be greater than 50%, 60%, 70%, 80%, 90%, or 95% by mass, based on the total mass of the oxidant. The oxidant can be composed of hydrogen peroxide (the oxidant contained in the grinding slurry is essentially 100% hydrogen peroxide).

[0085] Based on the total mass of the polishing slurry, the content of the oxidant can be within the following ranges. From the viewpoint of easily polishing tungsten materials at excellent polishing speeds, the oxidant content can be 0.01% by mass or more, 0.02% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1.0% by mass or more, 2.0% by mass or more, 2.5% by mass or more, or 3.0% by mass or more. From the viewpoint of easily reducing the roughness of the polished surface, the oxidant content can be 50% by mass or less, 30% by mass or less, 15% by mass or less, 10% by mass or less, 8.0% by mass or less, 5.0% by mass or less, 4.0% by mass or less, 3.5% by mass or less, or 3.0% by mass or less. From the above viewpoints, the oxidant content can be 0.01 to 50% by mass, 0.02 to 30% by mass, or 0.05 to 15% by mass.

[0086] The mass ratio R2 (oxidant content / abrasive content) of the oxidant to the abrasive content can be within the following ranges. From the viewpoint of easily grinding tungsten materials and insulating materials at excellent grinding speeds, the mass ratio R2 can be 0.01 or more, 0.05 or more, 0.1 or more, 0.5 or more, 1.0 or more, or 1.5 or more. From the viewpoint of balancing the grinding speeds of tungsten materials and insulating materials, the mass ratio R2 can be 2.0 or more, or 2.5 or more. From the viewpoint of easily grinding tungsten materials and insulating materials at excellent grinding speeds, the mass ratio R2 can be 10 or less, 8.0 or less, 6.0 or less, 4.0 or less, 3.0 or less, or 2.5 or less. From the viewpoint of balancing the grinding speeds of tungsten materials and insulating materials, the mass ratio R2 can be 2.0 or less, or 1.5 or less. From the above viewpoints, the mass ratio R2 can be 0.01 to 10, 0.1 to 8.0, or 0.5 to 6.0.

[0087] From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, the mass ratio R3 (oxidant content / iron compound content) of the oxidant content to the iron compound content can be within the following ranges: Mass ratio R3 can be 10 or more, 50 or more, 100 or more, 150 or more, 200 or more, 250 or more, 300 or more, or 350 or more. Mass ratio R3 can be 2000 or less, 1500 or less, 1000 or less, 800 or less, 600 or less, 500 or less, or 400 or less. From the above viewpoints, the mass ratio R3 can be 10–2000, 50–1000, or 100–500.

[0088] (Organic acid components)

[0089] The grinding fluid involved in this embodiment may contain an organic acid component (excluding compounds equivalent to iron-containing compounds or oxidizing agents). The organic acid component may be at least one selected from the group consisting of organic acids and their salts. Organic acids refer to organic compounds having an acid group (carboxyl group, sulfonyl group, etc.). Examples of salts of organic acids include alkali metal salts (e.g., sodium salts).

[0090] By including organic acid components in the polishing slurry, the oxidant can be easily maintained in a stable state within the slurry, thereby facilitating the polishing of tungsten materials at excellent speeds and extending the service life of the slurry. The inventors speculate the following reasons for achieving this effect. However, the reasons are not limited to the following. Specifically, it is speculated that the organic acid components will dissociate in the polishing slurry, releasing cations (protons, alkali metal ions, etc.) from at least one acid group to generate anionic groups (e.g., releasing protons (H+) from a carboxyl group (-COOH)). + And generate anionic groups (-COO) -Furthermore, the dissociated organic acid component chelates with the iron component (iron ions, etc.) of the iron-containing compound, thereby inhibiting the decomposition of the oxidant caused by the iron-containing compound and stabilizing the oxidant.

[0091] Examples of organic acid components include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylvaleric acid, heptanoic acid, 2-methylhexanoic acid, octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, adipic acid, glutamate, malic acid, citric acid, pimelic acid, maleic acid, phthalic acid, glycine, asparagine, alanine, glutamic acid, glutamine, valine, glutamine, leucine, isoleucine, lysine, serine, threonine, phenylalanine, tyrosine, methionine, tryptophan, β-alanine, and their salts. Organic acid components can be used as pH adjusters to adjust the pH of the polishing slurry. pH adjusters can be, for example, compounds that stabilize the pH of the polishing slurry between 2.0 and 4.0. pH adjusters may contain amino acid components (amino acids, their salts, etc.), or amino acid components with a first dissociation constant in the range of 2.0 to 4.0. As for the organic acid component, an organic acid component different from the amino acid component may be used.

[0092] From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, the component may contain at least one selected from the group consisting of carboxylic acids and carboxylate salts, or at least one selected from the group consisting of malonic acid, succinic acid, adipic acid, glutaric acid, malic acid, citric acid and their salts, or at least one selected from the group consisting of malonic acid and its salts as an organic acid component.

[0093] From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, the number of carbon atoms in the organic acid component (the number of carbon atoms in the compound used as the organic acid component) can be within the following ranges: The number of carbon atoms in the organic acid component can be 1 or more, 2 or more, or 3 or more. The number of carbon atoms in the organic acid component can be 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, or 3 or less. From the above viewpoints, the number of carbon atoms in the organic acid component can be 1 to 8.

[0094] From the viewpoint of easily maintaining the oxidant in a more stable state, thereby facilitating the grinding of tungsten materials at excellent grinding speeds, the organic acid component can be selected from the group consisting of divalent, trivalent, and tetravalent organic acid components. For example, "divalent organic acid component" refers to an organic acid component with two acid groups. Because the organic acid component has multiple acid groups, the dissociated organic acid component easily chelates with the iron component of iron-containing compounds, thereby easily inhibiting the decomposition of the oxidant caused by iron-containing compounds.

[0095] From the perspective of easily maintaining the oxidant in a more stable state, thereby facilitating the grinding of tungsten materials at excellent grinding speeds, an organic acid component without carbon-carbon unsaturated bonds can be included as the organic acid component. It is speculated that because the organic acid component lacks highly reactive carbon-carbon unsaturated bonds, it is easier to suppress the reaction between the organic acid component and the oxidant, thus making it easier to maintain the oxidant in a more stable state.

[0096] The organic acid component A can be selected from the group consisting of organic acids and their salts with a dissociation rate of 1% or more at pH 2.7. In this case, organic acid component A dissociates and readily chelates with the iron component of iron-containing compounds, thus stabilizing the oxidant. Therefore, tungsten materials can be ground at excellent grinding speeds, and the amount of organic acid component required can be reduced. From the same point of view, the dissociation rate of organic acid component A can be 3% or more, 5% or more, 10% or more, or 15% or more. Organic acid component A is particularly preferred when the pH of the grinding slurry is 2.0 to 4.0. The dissociation rate of organic acid component A can be calculated based on the pH of the grinding slurry, the acid dissociation constant of the organic acid component, etc. Examples of organic acid component A include malonic acid, succinic acid, glutaric acid, adipic acid, malic acid, citric acid, etc.

[0097] Regarding the organic acid component, from the viewpoint of easily grinding tungsten materials at an excellent grinding speed, as an organic acid component without carbon-carbon unsaturated bonds, it may include at least one selected from the group consisting of divalent organic acid components and trivalent organic acid components. As an organic acid component without carbon-carbon unsaturated bonds and with a dissociation rate of 1% or more at pH 2.7, it may include at least one selected from the group consisting of divalent organic acid components and trivalent organic acid components.

[0098] Based on the total mass of the grinding slurry, the content of organic acid components, the content of organic acid component A, or the content of organic acid components other than amino acids, i.e., content X, can be within the following ranges. From the viewpoint of easily grinding tungsten materials at excellent grinding speeds, content X can be 0.001% by mass or more, 0.005% by mass or more, 0.01% by mass or more, 0.02% by mass or more, 0.03% by mass or more, 0.035% by mass or more, or 0.04% by mass or more. From the viewpoint of easily reducing the roughness of the ground surface, content X can be 10% by mass or less, 5% by mass or less, 1% by mass or less, 0.8% by mass or less, 0.5% by mass or less, 0.3% by mass or less, 0.1% by mass or less, 0.08% by mass or less, 0.05% by mass or less, or 0.04% by mass or less. From the above viewpoints, content X can be 0.001 to 10% by mass, 0.005 to 5% by mass, or 0.01 to 1% by mass.

[0099] From the perspective that organic acid components readily chelate with iron ions, thus maintaining the oxidant in a stable state and facilitating the grinding of tungsten materials at excellent grinding speeds, the number of dissociated organic acid molecules relative to one iron atom can be 1.5 or more, 2 or more, 4 or more, or 6 or more. The number of dissociated organic acid molecules can be calculated based on the dissociation rate of the organic acid component. For example, when the grinding slurry pH is 2.7 and the iron ion (atomic weight 55.85) content is 0.001% by mass, and malonic acid (molecular weight 104.06) is used as the organic acid component, the dissociation rate of malonic acid at pH 2.7 is 52.8%. Therefore, the malonic acid content (the total amount of dissociated and undissociated malonic acid, and the amount of malonic acid incorporated) can be 0.007% by mass (the dissociated malonic acid is 2 molecules relative to one iron atom) or more. The number of dissociated malonic acid molecules relative to one atom of an iron ion can be calculated as follows: Calculate the mass of the iron ion based on its atomic weight and abundance, and then calculate the malonic acid content relative to one atom of an iron ion based on the mass of the iron ion, the dissociation rate and molecular weight of the malonic acid. The number of molecules of the dissociated organic acid component can be the number of molecules of an organic acid component that differs from the amino acid component.

[0100] (Other ingredients)

[0101] The polishing slurry of this embodiment may contain abrasive particles, iron-containing compounds, oxidants, organic acid components, or components other than water. As such components, the polishing slurry of this embodiment may contain inorganic acid components (inorganic acids and their salts), organic solvents, water-soluble polymers (anionic water-soluble polymers, etc.), cationic surfactants, cationic polymers having structural units derived from amino acids, (meth)acrylic acid polymers, polysaccharides, quaternary phosphonium salts, alkanolamine salts (alkyl sulfates, alkyl ether sulfates, etc.), compounds having a 1,2,3-triazolo[4,5-b]pyridine skeleton, cyclodextrins, toluenetriazole, diphenylguanidine, silylic molybdate compounds, aluminum components (aluminum ions, aluminum salts, etc.), etc., or may not contain at least one of these components (the content may be substantially 0% by mass based on the total mass of the polishing slurry).

[0102] Examples of inorganic acid components include phosphoric acid, sulfuric acid, and hydrochloric acid. Based on the total mass of the grinding slurry, the content of inorganic acid components, or the combined amount of phosphoric acid, sulfuric acid, hydrochloric acid, and nitric acid (oxidizing agent), can be less than 0.1% by mass, less than 0.05% by mass, less than 0.05% by mass, less than 0.01% by mass, or essentially 0% by mass.

[0103] Examples of organic solvents include methanol. Based on the total mass of the grinding fluid, the content of organic solvents or methanol can be less than 10% by mass, less than 7% by mass, less than 7% by mass, less than 1% by mass, less than 0.1% by mass, less than 0.01% by mass, less than 0.001% by mass, less than 0.0001% by mass, less than 0.0001% by mass, or substantially 0% by mass.

[0104] Based on the total mass of the grinding slurry, the content of water-soluble polymers, anionic water-soluble polymers, cationic surfactants, cationic polymers with structural units derived from amino acids, (meth)acrylic acid polymers, polysaccharides, quaternary phosphonium salts, alkanolamine salts, compounds with a 1,2,3-triazolo[4,5-b]pyridine skeleton, cyclodextrins, toluenetriazoles, diphenylguanidines, or silylic molybdate compounds may be less than 0.1% by mass, less than 0.1% by mass, less than 0.01% by mass, less than 0.01% by mass, less than 0.005% by mass, less than 0.005% by mass, less than 0.001% by mass, less than 0.001% by mass, less than 0.0001% by mass, less than 0.0001% by mass, less than 0.00001% by mass, less than 0.00001% by mass, or substantially 0% by mass.

[0105] The polishing slurry involved in this embodiment may be aluminum-free. Based on the total mass of the polishing slurry, the aluminum atom content may be less than 0.00001% by mass (100 ppb), less than 0.000006% by mass (60 ppb), less than 0.000006% by mass (60 ppb), less than 0.000005% by mass (50 ppb), less than 0.0000035% by mass (35 ppb), less than 0.000002% by mass (20 ppb), less than 0.000001% by mass (10 ppb), less than 0.0000005% by mass (5 ppb), or substantially 0% by mass. The aluminum atom content can be measured, for example, by the method described below.

[0106] Measurement method: ICP-MS

[0107] Measuring device: Inductively Coupled Plasma Quality Analyzer, manufactured by Agilent Technologies Japan, Ltd., product name "Agilent 8800"

[0108] Pretreatment: Mix the grinding slurry with an acid (hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, etc., at 0.1-10% by volume based on the total volume of the grinding slurry) and then dilute with ultrapure water (e.g., dilute 2-100 times).

[0109] (water)

[0110] The polishing slurry described in this embodiment can contain water. Examples of water include pure water, ultrapure water, and distilled water. The water content in the polishing slurry can be the balance of the slurry excluding the content of other contained components.

[0111] (pH of the grinding solution)

[0112] From the viewpoint of easily grinding tungsten materials and insulating materials at excellent grinding speeds and easily suppressing corrosion of the grinding apparatus, the pH of the grinding fluid in this embodiment can be 2.0 or higher, exceeding 2.0, 2.1 or higher, 2.2 or higher, 2.4 or higher, 2.5 or higher, exceeding 2.5, 2.6 or higher, or 2.7 or higher. From the viewpoint of easily suppressing etching of tungsten materials, the pH of the grinding fluid in this embodiment can be 4.0 or lower, less than 4.0, 3.7 or lower, 3.5 or lower, 3.3 or lower, 3.0 or lower, less than 3.0, 2.9 or lower, 2.8 or lower, or 2.7 or lower. From the above viewpoints, the pH of the grinding fluid can be 2.0 to 4.0, 2.1 to 3.7, 2.2 to 3.5, 2.5 to 3.5, or 2.5 to 3.0. The pH of the grinding fluid is defined as the pH at a liquid temperature of 25°C.

[0113] The pH of the polishing slurry in this embodiment can be measured using a pH meter (e.g., product name: Model (F-51) manufactured by HORIBA, Ltd.). For example, after calibrating the pH meter using phthalate pH standard solution (pH: 4.01), neutral phosphate pH standard solution (pH: 6.86), and borate pH standard solution (pH: 9.18) as calibration solutions, the pH meter is immersed in the polishing slurry, and the value is measured after stabilization for more than 2 minutes. At this time, the temperature of the calibration solution and the polishing slurry is set to 25°C.

[0114] (Save method)

[0115] From the viewpoint of minimizing costs associated with storage, transportation, and preservation, the grinding slurry according to this embodiment can be prepared as a storage solution for grinding slurry. The storage solution for grinding slurry contains less water than a predetermined amount for use, and can be used as a grinding slurry by diluting it with water before or during use. The storage solution for grinding slurry can be diluted with water just before grinding, or it can be diluted on the grinding plate by supplying the storage solution for grinding slurry and water to the grinding plate.

[0116] The grinding slurry described in this embodiment can be stored as a single-liquid grinding slurry containing at least abrasive particles, an iron-containing compound, and an oxidizing agent, or as a multi-liquid grinding slurry containing a slurry (first liquid) containing abrasive particles and an additive liquid (second liquid) containing an iron-containing compound and an oxidizing agent. In the multi-liquid grinding slurry, the components of the grinding slurry are divided into a slurry and an additive liquid, which are mixed to form the grinding slurry. Additives other than abrasive particles (iron-containing compounds, oxidizing agents, organic acid components, etc.) can be included in the additive liquid in the slurry and the additive liquid. The components of the grinding slurry can also be stored as three or more liquids. The slurry and additive liquid in the multi-liquid grinding slurry can be mixed to prepare the grinding slurry before or during grinding, or the slurry and additive liquid in the multi-liquid grinding slurry can be separately supplied to a grinding plate and mixed on the grinding plate to prepare the grinding slurry.

[0117] <Grinding Method>

[0118] The grinding method according to this embodiment includes a grinding step of grinding a surface containing tungsten material using the grinding slurry according to this embodiment. The grinding slurry used in the grinding step can be a single-component grinding slurry, a grinding slurry obtained by diluting a storage liquid for grinding slurry with water, or a grinding slurry obtained by mixing a slurry and an additive liquid in a multi-component grinding slurry.

[0119] The surface being ground can contain insulating materials, barrier materials (such as barrier metals), etc. Examples of insulating materials include silicon oxide and silicon nitride. Examples of barrier materials include tantalum, tantalum alloys, tantalum compounds (tantalum oxide, tantalum nitride, etc.), titanium, titanium alloys, titanium compounds (titanium oxide, titanium nitride, etc.), etc.

[0120] The grinding process can be a process of grinding a surface containing tungsten material and at least one selected from the group consisting of insulating material and barrier material using the grinding slurry according to this embodiment. The grinding process can be, for example, a process of grinding a substrate having a tungsten component (a component containing tungsten material) and at least one selected from the group consisting of insulating component (a component containing insulating material) and barrier component (a component containing barrier material).

[0121] like Figure 1As with the process of polishing the substrate 10, the polishing process can sequentially include: a first polishing process (coarse polishing process), in which the tungsten component 3 is polished until the blocking component 2 is exposed; a second polishing process, in which the blocking component 2 and the tungsten component 3 are polished until the insulating component 1 is exposed; and a third polishing process (fine polishing process), in which the insulating component 1, the blocking component 2, and the tungsten component 3 are polished. The polishing slurry involved in this embodiment can be used in at least one of the first polishing process, the second polishing process, and the third polishing process. The first polishing process, the second polishing process, and the third polishing process can be performed continuously using the polishing slurry involved in this embodiment, or a portion of the first polishing process, the second polishing process, and the third polishing process can be performed using the polishing slurry involved in this embodiment, and the remaining processes can be performed using other polishing slurries.

[0122] The object to be polished can be a film (polished film) or a tungsten film (a film containing tungsten material). Known methods for forming tungsten films include sputtering and deposition. In the polishing process, the polishing slurry described in this embodiment can be used to polish at least a portion of the polished film on a substrate (e.g., a substrate used in semiconductor device manufacturing) to remove the polished film (e.g., a tungsten film).

[0123] The grinding process can be, for example, the following steps: With the surface to be ground of the substrate pressed onto the grinding cloth (grinding pad) of the grinding disc, and a predetermined pressure applied to the substrate from the side opposite to the surface to be ground (the back side of the substrate), the grinding fluid according to this embodiment is supplied between the surface to be ground and the grinding cloth, and the substrate is moved relative to the grinding disc, thereby grinding the surface to be ground. There are no particular limitations on the grinding cloth; general nonwoven fabrics, polyurethane foam, porous fluoropolymers, etc., can be used.

[0124] In the grinding method described in this embodiment, the grinding apparatus can be, for example, a general grinding apparatus equipped with a motor capable of changing rotation speed, and having a grinding disc for attaching grinding cloth and a holder for holding the substrate. There are no particular limitations on the grinding conditions; the rotation speed of the grinding disc can be adjusted to 200 min. -1 A low rotation speed of 200 rpm or less is used to prevent the substrate from flying off the grinding disc. From the viewpoint of easily adjusting the uniformity of the grinding speed and the flatness of the pattern within the surface being ground to an optimal range, the pressing pressure of the substrate with the surface to be ground on the grinding cloth can be 1–100 kPa or 5–50 kPa. During grinding, a pump or similar device can be used to continuously supply grinding fluid to the grinding cloth. There is no limit to the amount of grinding fluid supplied; it is sufficient that the surface of the grinding cloth is always covered with grinding fluid.

[0125] The polishing method described in this embodiment may include a finishing step that finishes the polishing cloth before each polishing step, so that polishing (CMP, etc.) is performed while the surface condition of the polishing cloth remains the same. In the finishing step, for example, a finisher with diamond particles is used to finish the polishing cloth with a liquid containing at least water.

[0126] The grinding method described in this embodiment can include a cleaning step after the grinding process to clean the substrate. In the cleaning step, for example, after thoroughly cleaning the substrate with running water after grinding, a rotary dryer or similar device can be used to shake off water droplets adhering to the substrate before drying. Furthermore, a known cleaning method can be implemented (for example, a method of removing deposits from the substrate by rotating a polyurethane brush while pressing it against the substrate with a predetermined pressure while flowing a commercially available cleaning solution over the surface of the substrate). Afterward, the substrate can be dried.

[0127] The manufacturing method for a component according to this embodiment includes a component fabrication step in which a component is obtained by polishing a substrate (a substrate being polished) using the polishing method of this embodiment. The component according to this embodiment can be obtained by the manufacturing method of the component according to this embodiment. The component according to this embodiment is not particularly limited and can be an electronic component (e.g., a semiconductor component such as a semiconductor package), a wafer (e.g., a semiconductor wafer), or a wafer (e.g., a semiconductor wafer). As one aspect of the manufacturing method for a component according to this embodiment, in the manufacturing method for an electronic component according to this embodiment, an electronic component is obtained by polishing a substrate using the polishing method of this embodiment. As another aspect of the manufacturing method for a component according to this embodiment, in the manufacturing method for a semiconductor component according to this embodiment, a semiconductor component (e.g., a semiconductor package) is obtained by polishing a substrate using the polishing method of this embodiment before the component fabrication step. The manufacturing method for a component according to this embodiment may include a polishing step in which the substrate is polished using the polishing method of this embodiment before the component fabrication step.

[0128] In the manufacturing method of the component according to this embodiment, as one aspect of the component manufacturing process, a wafer-level step may be included, which involves wafer-leveling the substrate (the object being polished) polished by the polishing method according to this embodiment. The wafer-leveling step may, for example, be a step of dicing a wafer (e.g., a semiconductor wafer) polished by the polishing method according to this embodiment to obtain a wafer (e.g., a semiconductor wafer). As one aspect of the manufacturing method of the component according to this embodiment, the manufacturing method of the electronic component according to this embodiment may include a step of wafer-leveling the substrate polished by the polishing method according to this embodiment to obtain an electronic component (e.g., a semiconductor component). As one aspect of the manufacturing method of the component according to this embodiment, the manufacturing method of the semiconductor component according to this embodiment may include a step of wafer-leveling the substrate polished by the polishing method according to this embodiment to obtain a semiconductor component (e.g., a semiconductor package).

[0129] In the part manufacturing method described in this embodiment, as one part manufacturing process, a connection step may be included to connect (e.g., electrically connect) a substrate (the workpiece being polished) polished by the polishing method described in this embodiment to other connected bodies. The connected body to the substrate polished by the polishing method described in this embodiment is not particularly limited; it can be the same substrate polished by the polishing method described in this embodiment, or it can be a different connected body. In the connection step, the substrate and the connected body can be directly connected (connected while the substrate and the connected body are in contact), or they can be connected via other components (conductive components, etc.). The connection step can be performed before, after, or both before and after the monolithization process.

[0130] The joining process can be either a process of joining the polished surface of a substrate polished by the polishing method according to this embodiment to the joined body, or a process of joining the joining surface of the substrate polished by the polishing method according to this embodiment to the joining surface of the joined body. The joining surface of the substrate can be the polished surface polished by the polishing method according to this embodiment. Through the joining process, a joined body having a substrate and a joined body can be obtained. In the joining process, if the joining surface of the substrate has a metal portion, the joined body can be brought into contact with the metal portion. In the joining process, if both the joining surface of the substrate and the joining surface of the joined body have metal portions, the metal portions can be brought into contact with each other. The metal portion may contain tungsten material.

[0131] The device (e.g., an electronic device such as a semiconductor device) involved in this embodiment includes at least one selected from the group consisting of a substrate that is polished by the polishing method involved in this embodiment and a part involved in this embodiment.

[0132] Example

[0133] The present invention will be described in more detail below with reference to embodiments, but the present invention is not limited to these embodiments.

[0134] <Measurement of average particle size and silanol group density>

[0135] The average particle size and silanol density of silica particles (abrasive grains) were measured. The average particle size was measured using a COULTER N4SD manufactured by Coulter Electronics, Inc., within the range of measurement temperature: 20°C, solvent refractive index: 1.333 (water), particle refractive index: Unknown (set), solvent viscosity: 1.005cp (water), run time: 200 seconds, laser incident angle: 90°, and intensity: 5E+04 to 4E+05. The measurements were performed in the order described above [1] to [8], and the silanol density was calculated. The results are shown in Tables 1 and 2.

[0136] <Preparation of Grinding Fluid>

[0137] A grinding slurry containing silica particles (abrasive particles, colloidal silica), ferric nitrate nonahydrate (iron-containing compound, iron ion supplier), and malonic acid (organic acid component) was prepared by mixing deionized water, silica particles (abrasive particles, colloidal silica), ferric nitrate nonahydrate (iron-containing compound, iron ion supplier), and hydrogen peroxide (oxidant). The silica particle content was adjusted as shown in Tables 1 and 2 (unit: mass%).

[0138] <Measurement of Zeta Potential>

[0139] The zeta potential (25°C) of silica particles (abrasive grains) in the polishing slurries of each embodiment was measured. The zeta potential of the silica particles in the polishing slurry at 25°C was measured using DT1202 (product name) manufactured by Nihon Rufuto Co., Ltd. The results are shown in Table 1.

[0140] <Aluminum atom content>

[0141] The aluminum atom content in the polishing slurry of each embodiment was measured. In all embodiments, the aluminum atom content was less than 0.0000005% by mass (5 ppb) based on the total mass of the polishing slurry.

[0142] <pH Measurement>

[0143] The pH of each polishing slurry was measured as follows, and the results showed that the pH of the polishing slurries in all examples and comparative examples was 2.7.

[0144] Measuring instrument: pH meter (HORIBA, Ltd., Product name: Model (F-51))

[0145] Calibration solutions: Phthalate pH standard solution (pH: 4.01 (25℃)), neutral phosphate pH standard solution (pH: 6.86 (25℃)) and borate pH standard solution (pH: 9.18 (25℃)).

[0146] Temperature measured: 25℃

[0147] Measurement method: After three-point calibration using calibration solution, the electrode was placed in the grinding slurry and left at 25°C for more than 2 minutes to measure the pH after it stabilized.

[0148] <Evaluation>

[0149] The grinding speeds of tungsten and silicon oxide films on the following substrates were obtained by grinding under the following grinding conditions. The grinding speed of tungsten was obtained by measuring the resistance of the tungsten film before and after grinding using a VR-120 / 08S resistance meter (manufactured by Hitachi Kokusai Electric Inc.), dividing the difference in film thickness before and after grinding calculated from the resistance by the grinding time. The grinding speed of silicon oxide was obtained by measuring the difference in film thickness before and after grinding using an F50 optical film thickness gauge (manufactured by Filmetrics, INC.), dividing the difference in film thickness by the grinding time. The results are shown in Tables 1 and 2. As shown in Table 1, in Examples 1 to 6, it can be seen that tungsten materials can be ground at excellent grinding speeds.

[0150] [Matrix]

[0151] Substrate with tungsten film: Substrate (diameter: 12 inches) with a tungsten film (thickness: 700 nm) formed on a silicon substrate.

[0152] Substrate with silicon oxide film: Substrate (diameter: 12 inches) with a TEOS (tetraethoxysilane) film (thickness: 1000 nm) formed on a silicon substrate.

[0153] [Grinding conditions]

[0154] CMP grinding mill: Manufactured by Applied Materials, Inc., product name "ReflexionL".

[0155] Abrasive pad: IC1010 (Nitta Haas Incorporated.)

[0156] Grinding pressure: 20.7 kPa

[0157] Fixed plate speed: 90 rpm

[0158] Magnetic head speed: 87 rpm

[0159] CMP slurry supply rate: 300 mL / min

[0160] Polishing time for tungsten film and silicon oxide film: 0.5 minutes

[0161] [Table 1]

[0162]

[0163] [Table 2]

[0164]

[0165] Symbol Explanation

[0166] 1-Insulating component, 2-Barrier component, 3-Tungsten component, 10-Substrate.

Claims

1. A polishing liquid for polishing a polished surface containing a tungsten material, the polishing liquid containing abrasive grains, an iron-containing compound, and an oxidizing agent, the abrasive grains contain silica particles, the average particle diameter of the abrasive grains is 40 to 140 nm, The silanol group density of the silica particles is 8.0 / nm 2 Hereinafter, the Zeta potential of the silica particles in the polishing liquid is 4 mV or less, the content of aluminum atoms is 0.000005 mass% or less based on the total mass of the polishing liquid.

2. The polishing liquid according to claim 1, wherein the average particle diameter of the abrasive grains is 40 to 85 nm.

3. The polishing liquid according to claim 1, wherein The silanol group density of the silica particles is 2.5 / nm 2 The following.

4. The polishing liquid according to claim 1, wherein The silica particles have a silanol group density of less than 2.0 per nm 2 .

5. The polishing liquid according to claim 1, wherein the Zeta potential of the silica particles in the polishing liquid is more than -10 mV.

6. The polishing liquid according to claim 1, wherein the iron-containing compound contains at least one selected from the group consisting of iron nitrate and hydrates thereof.

7. The polishing liquid according to claim 1, wherein the content of the iron-containing compound is 0.0001 to 0.1 mass% based on the total mass of the polishing liquid.

8. The polishing liquid according to claim 1, wherein the oxidizing agent contains hydrogen peroxide.

9. The polishing liquid according to claim 1, further containing an organic acid component.

10. The polishing liquid according to claim 9, wherein the organic acid component contains at least one selected from the group consisting of a bivalent organic acid component and a trivalent organic acid component as an organic acid component not containing a carbon-carbon unsaturated bond.

11. The polishing liquid according to claim 9, wherein the organic acid component contains at least one selected from the group consisting of malonic acid, succinic acid, adipic acid, glutaric acid, malic acid, citric acid, and salts thereof.

12. The polishing liquid according to claim 1, having a pH of 2.0 to 4.

0.

13. The polishing liquid according to claim 1, having a pH of 2.5 to 3.

5.

14. A polishing method in which a polished surface containing a tungsten material is polished using the polishing liquid according to any one of claims 1 to 13.

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