Polishing composition, polishing method, and substrate manufacturing method

Abstract

To provide: a polishing composition which has a high removal rate for a polishing target, a high selection ratio of the polishing target to other kinds of films, and better stability; and a polishing method.SOLUTION: The polishing composition comprises abrasive grains with a positive zeta potential, an oxidant, a nitrogen-containing surfactant, a polishing rate improver, and an aqueous dispersion medium. The polishing method comprises introducing the polishing composition into between a substrate 20 and a polishing pad, and then polishing the substrate. The substrate comprises a dielectric base material 201, a metal material 205, and a liner layer 203 disposed therebetween. The polishing composition has a high removal rate for the metal material and a high selection ratio of the metal material to other kinds of films.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a polishing composition and a polishing method using the same. [Background technology]

[0002] In the current semiconductor industry, planarization techniques are typically used to increase the flatness of semiconductor substrate or wafer surfaces to remove excess material or provide a completely flat substrate for the next layer of circuit structure. Planarization techniques include thermal flow, etch-back processes, and chemical mechanical polishing (CMP) processes. Thermal flow and etch-back processes can achieve local planarization of the semiconductor substrate or wafer surface, while CMP can achieve global planarization of the semiconductor substrate or wafer surface. CMP achieves the goal of planarization by using a polishing pad and polishing head with an abrasive and corrosive polishing composition to remove material and irregular structures from the semiconductor substrate or wafer surface.

[0003] The components of the polishing composition used in the CMP process, a planarization process, vary depending on the object to be polished. Patent Documents 1 to 4 disclose polishing compositions with different components used to treat different objects to be polished. Patent Documents 1 to 4 show that the composition of a polishing composition usually contains an oxidizing agent and abrasive grains. The oxidizing agent can oxidize the object to be polished to turn it into an oxide with a relatively low hardness, which is convenient for the subsequent physical polishing with abrasive grains, thereby increasing the removal rate of the CMP process. However, there is still a need for a polishing composition that can further increase the removal rate of the object to be polished. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-061612 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-194006 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-224767 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-149402 Summary of the Invention [Problem to be solved by the invention]

[0005] A polishing composition having a high removal rate for an object to be polished, a high selectivity with respect to other film types, and excellent stability is provided. [Means for solving the problem]

[0006] To achieve the above object, one aspect of the present invention provides a polishing composition comprising abrasive grains having a positive zeta potential, an oxidizing agent, a nitrogen-containing surfactant, a polishing rate enhancer, and an aqueous dispersion medium.

[0007] Another aspect of the present invention further provides a polishing method that can achieve the above-mentioned object, comprising the steps of preparing a polishing apparatus including a polishing pad and a polishing head, preparing a substrate between the polishing pad and the polishing head, and introducing a polishing composition between the substrate and the polishing pad and then polishing the substrate, wherein the polishing composition comprises abrasive grains having a positive zeta potential, an oxidizing agent, a nitrogen-containing surfactant, a polishing rate enhancer, and an aqueous dispersion medium. [Effects of the Invention]

[0008] The polishing composition of the present invention has a high removal rate for the material to be removed, a high selectivity relative to other film types, and is more stable. By using the polishing method of the present invention, a semiconductor substrate or wafer surface of higher quality can be obtained, and the manufacturing cost of semiconductor substrates or wafers can be reduced. [Brief explanation of the drawings]

[0009] The disclosure is more fully set forth in the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a flowchart of a polishing method according to an embodiment of the present invention. [Figure 2] 2A and 2B are cross-sectional views of a substrate at different stages of a polishing method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Although the embodiments of the present invention will be described below, the present invention is not limited to the following embodiments.

[0011] It will be understood that when "comprising" is used herein, it indicates the presence of stated feature members, integers, steps, operations, elements, compositions, and / or groups thereof, but does not exclude the presence or multiplication of one or more other feature members, integers, steps, operations, elements, compositions, and / or groups thereof. Where the singular form is used herein, the plural form is also intended to be included unless the context clearly indicates otherwise.

[0012] In this specification, the expression "a to b" used to express a specific range of numerical values ​​is defined as "≧a, ≦b".

[0013] <Polishing composition> The polishing composition of the present invention contains abrasive grains having a positive zeta potential, an oxidizing agent, a nitrogen-containing surfactant, a polishing rate enhancer, and an aqueous dispersion medium.

[0014] The present inventors speculate as follows about the mechanism for solving the above-mentioned problems.

[0015] It is considered that when the nitrogen-containing surfactant interacts with abrasive grains having a positive zeta potential in an acidic environment, the mechanical polishing rate for the tungsten oxide surface is accelerated and the tungsten removal rate is increased. Such a mechanism is based on speculation, and whether it is correct or not does not affect the technical scope of the present invention.

[0016] Hereinafter, each component contained in the polishing composition, the polishing object, etc. will be described.

[0017] <pH value> The pH value of the polishing composition of the present invention is preferably 1 or more, more preferably 1.5 or more, and still more preferably 2 or more. The pH value of the polishing composition of the present invention is preferably less than 7, more preferably 5 or less, and still more preferably 4 or less. The pH value of the polishing composition of the present invention is preferably in the range of 2 to 4. When the pH is within the above range, the polishing composition of the present invention can have a high removal rate for tungsten and a high selectivity ratio with other film types, and the stability is further enhanced.

[0018] <Abrasive grains> As used herein, the "zeta (ζ) potential" refers to the potential difference generated at the interface between a solid and a liquid in relative motion when they come into contact with each other, and directly reflects the stability of the system. When the zeta potential of the particles in the suspension system is close to 0, those particles are likely to aggregate, indicating that the system is unstable and difficult to store. When the particles in the suspension system have a zeta potential that is clearly a negative value or a positive value, those particles strongly repel each other and are well dispersed in the system, indicating that the stability of the system is enhanced. The zeta potential of the abrasive grains of the present invention is preferably 5 mV or more, more preferably 10 mV or more, and still more preferably 20 mV or more. With abrasive grains having a zeta potential within such a range, the polishing rate and the stability of the polishing composition can be enhanced.

[0019] Here, the zeta potential of the abrasive grains in the polishing composition can be measured by subjecting the polishing composition to an ELS-Z2 manufactured by Otsuka Electronics Co., Ltd., measuring it using a flow cell at a measurement temperature of 25°C using the laser Doppler method (electrophoretic light scattering measurement method), and analyzing the obtained data using the Smoluchowski formula to calculation.

[0020] Examples of abrasive grains in the polishing composition include, but are not limited to, alumina, silica, zirconia, diamond, or silicon carbide. The abrasive grains may be used alone or in combination of two or more types. The abrasive grains may be commercially available or synthetic.

[0021] The type of abrasive grains is preferably silica, more preferably colloidal silica.Methods for producing colloidal silica include the sodium silicate method and the sol-gel method, and colloidal silica produced by either method can be suitably used as the abrasive grains of the present invention.However, from the viewpoint of reducing metal impurities, colloidal silica produced by the sol-gel method, which can be produced with high purity, is preferred.

[0022] Colloidal silica can be produced by the sol-gel method using a conventionally known method. Specifically, colloidal silica can be obtained by using a hydrolyzable silicon compound (e.g., an alkoxysilane or a derivative thereof) as a raw material and carrying out a hydrolysis-condensation reaction.

[0023] In an embodiment in which the abrasive grains are silica, abrasive grains with a positive zeta potential can be obtained by substituting at least a portion of the hydrogen atoms constituting the silanol groups located on the surface of the colloidal silica with metal cations derived from aluminum, chromium, titanium, zirconium, iron, zinc, tin, scandium, gallium, or a group consisting of these metal atoms, but the present invention is not limited thereto. In another embodiment, abrasive grains with a positive zeta potential can be obtained by bonding cationic groups, such as amine groups or quaternary cation groups, to the surface of the abrasive grains. The abrasive grains with a positive zeta potential used in the present invention can be prepared by hand or purchased commercially.

[0024] The term "silanol group" as used herein refers to a hydroxyl group directly bonded to a silicon atom on the surface of a silica particle, and there are no particular limitations on the steric configuration or configuration. There are also no particular limitations on the conditions for generating the silanol group. The term "silanol group density" as used herein refers to the number of silanol groups per unit area on the surface of a silica particle, and serves as an index of the electrical or chemical properties of the surface of the silica particle. In an embodiment in which silica may be contained in the abrasive grain, the silanol group density of the abrasive grain is 0 to 10.0 groups / nm 2 is preferably 1.0 to 6.0 particles / nm 2 More preferably, the number is 1.5 to 5.7 / nm 2 When the abrasive grains in the polishing composition have a silanol group density within the above range, the polishing composition can achieve good polishing properties and has better stability.

[0025] Here, the silanol group density of the abrasive grains in the polishing composition is calculated based on the specific surface area measured by the BET method and the amount of silanol groups measured by titration.For example, the average silanol group density (unit: particles / nm) on the surface of silica (polishing grains) is calculated by the Sears titration method using neutralization titration described in "Analytical Chemistry, vol.28, No.12, 1956, 1982-1983" by GW Sears. 2 ) can be calculated.

[0026] Here, the shape of the abrasive grains is not particularly limited and may be spherical or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular prisms and square prisms, cylinders, bale-shaped cylinders in which the center is more bulging than the ends, doughnut-shaped discs with a central hole, plate-shaped discs, cocoon-shaped discs with a central constriction, associative spheres in which multiple particles are integrated, confetti-shaped discs with multiple protrusions on the surface, and rugby ball-shaped discs, and are not particularly limited.

[0027] The size of the abrasive grains is not particularly limited. For example, in the polishing composition of the present invention, the lower limit of the average primary particle diameter of the abrasive grains is preferably 1 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more. In addition, in the polishing composition of the present invention, the upper limit of the average primary particle diameter of the abrasive grains is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 65 nm or less, and particularly preferably 50 nm or less. Within such ranges, defects such as scratches that may occur on the surface of the object to be polished after polishing with the polishing composition can be suppressed. The average primary particle diameter of the abrasive grains is calculated, for example, based on image observation using a scanning electron microscope (SEM).

[0028] In the polishing composition of the present invention, the lower limit of the average secondary particle diameter of abrasive grains is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 40 nm or more, and particularly preferably 50 nm or more.In addition, in the polishing composition of the present invention, the upper limit of the average secondary particle diameter of abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, even more preferably 120 nm or less, and particularly preferably 90 nm or less.Within this range, defects such as scratches that may occur on the surface of the object to be polished after polishing with the polishing composition can be suppressed.

[0029] The secondary particles are particles formed by the aggregation of abrasive grains (primary particles) in the polishing composition. The average secondary particle size of the abrasive grains can be measured, for example, by a dynamic light scattering method, such as a laser diffraction scattering method.

[0030] The content (concentration) of abrasive grains is not particularly limited. The total weight of the polishing composition is taken as 100 wt%, and the content of abrasive grains in the polishing composition is preferably 0.01 wt% or more, more preferably 0.1 wt% or more, and most preferably 1 wt% or more. The higher the content of abrasive grains in the polishing composition, the higher the removal rate of the polishing composition from the object to be polished. The content of abrasive grains in the polishing composition is preferably 20 wt% or less, more preferably 15 wt% or less, and most preferably 10 wt% or less. The lower the content of abrasive grains in the polishing composition, the lower the scratch defect rate on the surface of the object to be polished. In other words, the content of abrasive grains in the polishing composition is preferably within the range of 0.01 to 20 wt%, more preferably within the range of 0.1 to 15 wt%, and most preferably within the range of 1 to 10 wt%. In one embodiment, the content of abrasive grains in the polishing composition is 5 wt%. When the content of abrasive grains in the polishing composition is within the above range, the polishing composition can increase the removal rate of the object to be polished while maintaining a low scratch defect rate of the object to be polished, thereby providing excellent polishing properties.

[0031] <Oxidizing agent> The oxidizing agent in the polishing composition of the present invention may be any compound capable of oxidizing the object to be polished to form an oxide. The oxidizing agent is not particularly limited. Examples of oxidizing agents include, but are not limited to, hydrogen peroxide, sodium peroxide, barium peroxide, ozone water, silver (II) salts, iron (III) salts, permanganic acid, chromic acid, dichromate, peroxodisulfuric acid, peroxolinic acid, peroxosulfuric acid, peroxoboric acid, performic acid, peracetic acid, perbenzoic acid, perphthalic acid, hypochlorous acid, hypobromous acid, hypoiodous acid, chloric acid, chlorous acid, perchloric acid, bromic acid, iodic acid, periodic acid, persulfuric acid, dichloroisocyanuric acid, and salts thereof. Among these, hydrogen peroxide, iron salts, hypochlorous acid, periodic acid, and persulfuric acid are preferred, and periodic acid is more preferred.

[0032] There are no particular limitations on the content (concentration) of the oxidizing agent. The content of the oxidizing agent in the polishing composition is preferably 0.01 wt% or more, more preferably 0.05 wt% or more, and most preferably 0.1 wt% or more, assuming the total weight of the polishing composition to be 100 wt%. The higher the content of the oxidizing agent in the polishing composition, the stronger the chemical polishing effect of the polishing composition on the object to be polished. The content of the oxidizing agent in the polishing composition is preferably 10 wt% or less, more preferably 5 wt% or less, and most preferably 1 wt% or less. The lower the content of the oxidizing agent in the polishing composition, the stronger the physical polishing effect of the polishing composition on the object to be polished. In other words, the content of the oxidizing agent in the polishing composition is preferably in the range of 0.01 to 10 wt%, more preferably 0.05 to 0.5 wt%, and most preferably 0.1 to 1 wt%. When the content of the oxidizing agent in the polishing composition is within the above range, the polishing composition achieves a balance between the physical polishing effect and the chemical polishing effect, thereby providing excellent polishing properties.

[0033] <Nitrogen-containing surfactants> The nitrogen-containing surfactant used in the polishing composition of the present invention is preferably an ammonium salt, an amine oxide, an amine, or any combination thereof. The nitrogen-containing surfactant is preferably a compound represented by one of the following chemical formulas:

[0034] [ka]

[0035] In the formula, R 1 , R 2 , R 3 , R 4 , R 5 each independently represents a C1-C20 alkyl group, and X represents a halogen atom.

[0036] As used herein, the term "C1-C20 alkyl group" refers to a monovalent hydrocarbon group remaining after removing one hydrogen atom from a saturated hydrocarbon molecule containing from 1 to 20 carbon atoms. The C1-C20 alkyl group may be a straight-chain alkyl group, a branched alkyl group, or a cyclic alkyl group. Straight-chain examples may include, but are not limited to, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups. Examples of branched alkyl groups may include, but are not limited to, isopropyl, isobutyl, s-butyl, t-butyl, t-amyl, neopentyl, 3-methylpentyl, 1,1-diethylpropyl, 1,1-dimethylbutyl, 1-methyl-1-propylbutyl, 1,1-dipropylbutyl, 1,1-dimethyl-2-methylpropyl, and 1-methyl-1-isopropyl-2-methylpropyl groups. Examples of cyclic alkyls may include, but are not limited to, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and norbornenyl groups.

[0037] More preferably, the nitrogen-containing surfactant is a compound represented by one selected from the following chemical formulas:

[0038] [ka]

[0039] In the formula, m and n each independently represent a number from 1 to 10.

[0040] There are no particular limitations on the content (concentration) of the nitrogen-containing surfactant. The content of the nitrogen-containing surfactant in the polishing composition is preferably 0.001 wt% or more, more preferably 0.005 wt% or more, and most preferably 0.01 wt% or more, assuming the total weight of the polishing composition to be 100 wt%. The content of the nitrogen-containing surfactant in the polishing composition is preferably 1 wt% or less, more preferably 0.5 wt% or less, and most preferably 0.2 wt% or less. In other words, the content of the nitrogen-containing surfactant in the polishing composition is preferably 0.001 to 1 wt%, more preferably 0.005 to 0.5 wt%, and most preferably 0.01 to 0.2 wt%. When the polishing composition contains a nitrogen-containing surfactant whose content is within the above range, it exhibits excellent polishing properties.

[0041] <Polishing speed enhancer> The polishing rate enhancer in the polishing composition of the present invention is a compound used to increase the removal rate of the object to be polished. There is no particular limitation on the polishing rate enhancer. Examples of the polishing rate enhancer include, but are not limited to, nitrogen-containing compounds, inorganic acid salts, quaternary ammonium compounds, or any combination thereof. In one embodiment, the polishing rate enhancer is a nitrate.

[0042] There are no particular limitations on the content (concentration) of the polishing rate enhancer. With the total weight of the polishing composition taken as 100 wt%, the content of the polishing rate enhancer in the polishing composition is preferably 0.1 wt% or more, more preferably 0.5 wt% or more, and most preferably 1.0 wt% or more. The content of the polishing rate enhancer in the polishing composition is preferably 5.0 wt% or less, more preferably 3.0 wt% or less, and most preferably 1.5 wt% or less. In other words, the content of the polishing rate enhancer in the polishing composition is preferably within the range of 0.1 to 5.0 wt%, more preferably 0.5 to 3.0 wt%, and most preferably 1.0 to 1.5 wt%.

[0043] <Aqueous dispersion medium> The function of the aqueous dispersion medium in the polishing composition is to dissolve or disperse each of the above-described components in the polishing composition. There is no particular limitation on the example of the aqueous dispersion medium. Also, there is no particular limitation on the water content in the aqueous dispersion medium, and it is preferably 50 wt% or more, more preferably 90 wt%, and even more preferably only water, based on the total weight of the aqueous dispersion medium. From the viewpoint of suppressing contamination of the object to be polished and inhibition of the action of other components, water containing as few impurities as possible is preferable as the dispersion medium. As such water, water having a total content of transition metal ions of 100 ppb or less is suitable. Here, the purity of water can be increased by operations such as removal of impurity ions using an ion exchange resin, removal of foreign substances by a filter, distillation, and the like. Specifically, as water, deionized water (ion-exchanged water), pure water, ultrapure water, distilled water, etc. are preferably used. In one embodiment, the aqueous dispersion medium contains deionized water.

[0044] As long as the dispersibility or solubility of each component can be enhanced, the aqueous dispersion medium may be a mixed solvent of water and an organic solvent. There is no particular limitation on the organic solvent, and known organic solvents can be used. When using a mixed solvent of water and an organic solvent, an organic solvent mixed with water is preferable. When using an organic solvent, after mixing water and the organic solvent to form a mixed solvent, each component may be added to and mixed with the mixed solvent, or after dispersing or dissolving each component in the organic solvent, it may be mixed with water. Also, the organic solvent may be used alone or in combination of two or more kinds.

[0045] <pH adjuster> The polishing composition may further contain a pH adjuster. By adjusting the pH value of the polishing composition within an appropriate range, the pH adjuster can enhance the chemical polishing effect of the polishing composition or improve the dispersion stability of the polishing composition. There are no particular limitations on the pH adjuster used in the polishing composition of the present invention, as long as it can adjust the pH value of the polishing composition of the present invention within the desired range. The pH adjuster used in the present invention is preferably an alkaline substance, and examples thereof include, but are not limited to, nitrogen-containing compounds, inorganic bases, quaternary ammonium compounds, or any combination thereof. In one embodiment, the pH adjuster may be ammonium hydroxide (NH4OH), tetraethylammonium hydroxide (TEAH), or any combination thereof. The pH adjuster may be used alone or in combination of two or more types.

[0046] The amount (concentration) of the pH adjuster to be added can be appropriately selected so as to adjust the polishing composition to the desired pH value, and an amount that can adjust the polishing composition to the preferred pH value described below is preferred.

[0047] <Other ingredients> The polishing composition of the present invention may further contain other components within the range that does not impair the effects of the present invention. The other components are not particularly limited and can be appropriately selected from various components used in known polishing compositions, including, for example, wetting agents, chelating agents, preservatives, antifungal agents, dissolved gases, reducing agents, etc.

[0048] <Method for producing polishing composition> The method for producing the polishing composition of the present invention is not particularly limited, and can be obtained, for example, by mixing and stirring abrasive grains, an oxidizing agent, a nitrogen-containing surfactant, a polishing rate enhancer, and other components (e.g., a pH adjuster) as needed in an aqueous dispersion medium (e.g., water). Details of each component are as described above. The temperature and mixing time for mixing each component are not particularly limited, as long as the components of the polishing composition are mixed uniformly.

[0049] <Object to be polished> The polishing object of the present invention is not particularly limited, and known polishing objects applicable to CMP can be used. Therefore, the form of the polishing object is not particularly limited, but a substrate filled with a metal material is preferred, and a substrate further including a liner layer between the metal material and the substrate is more preferred. The substrate is preferably a silicon substrate. In one embodiment, the liner layer may include a metal nitride layer, a barrier film, or a combination thereof. Examples of barrier film materials may include, but are not limited to, titanium, tantalum, or a combination thereof. The metal nitride layer may include, but is not limited to, titanium nitride, tantalum nitride, or a combination thereof.

[0050] <Polishing method> Another aspect of the present invention provides a polishing method for polishing an object to be polished using the polishing composition described above. The polishing method of the present invention will be described in more detail below with reference to Figures 1, 2A, and 2B. Figure 1 is a flowchart of a polishing method 10 according to an embodiment of the present invention. Figures 2A and 2B are cross-sectional views of a substrate 20 at different stages of the polishing method 10 according to an embodiment of the present invention.

[0051] As shown in FIG. 1, a polishing method 10 according to an embodiment of the present invention includes step S101 of preparing a polishing apparatus including a polishing pad and a polishing head, step S103 of preparing a substrate between the polishing pad and the polishing head, and step S105 of introducing a polishing composition between the substrate and the polishing pad and then polishing the substrate.

[0052] The polishing apparatus prepared in step S101 is not particularly limited, and any suitable known apparatus can be used. The polishing apparatus can be a general polishing apparatus equipped with a holder for holding the object to be polished, a motor with an adjustable rotation speed, and a polishing platen onto which a polishing pad (polishing cloth) can be attached. Either a single-sided polishing apparatus or a double-sided polishing apparatus can be used. The polishing pad can be made of general nonwoven fabric, polyurethane, porous fluororesin, etc., without any particular limitations. It is preferable that the polishing pad has grooves formed to allow the polishing liquid to collect.

[0053] The substrate prepared between the polishing pad and the polishing head in step S103 may have the structure shown in FIG. 2A. As shown in FIG. 2A, the substrate 20 includes a dielectric substrate 201 and a metal material 205. The dielectric substrate 201 has a plurality of grooves, and the metal material 205 fills these concave grooves, and at least a portion of the metal material 205 is formed on the surface of the dielectric substrate 201 or protrudes from the surface of the dielectric substrate 201. Although FIG. 2A shows an embodiment in which the metal material 205 covers the entire surface of the dielectric substrate 201, the present invention is not limited thereto. In one embodiment, the metal material 205 may cover only a portion of the surface of the dielectric substrate 201. In one embodiment, the dielectric substrate 201 may include silicon oxide (SiO2). In one embodiment, the metal material 205 may include tungsten.

[0054] In one embodiment, substrate 20 may further include a liner layer 203. Liner layer 203 may be conformally formed on dielectric substrate 201 having a plurality of grooves and may be disposed between dielectric substrate 201 and metal material 205. Liner layer 203 may include a metal nitride layer, a barrier film, or a combination thereof. In one embodiment, the barrier film may include titanium, tantalum, or a combination thereof. In one embodiment, the metal nitride layer may include titanium nitride, tantalum nitride, or a combination thereof.

[0055] 2A is placed between the polishing pad and the polishing head, with the metal material 205 facing the polishing pad. Then, in step S105, the polishing composition is introduced between the substrate 20 and the polishing pad, and the substrate 20 is then polished.

[0056] The polishing conditions used in the polishing step of step S105 are not particularly limited, and appropriate conditions can be set appropriately depending on the characteristics of the polishing composition and the object to be polished. The polishing load (polishing pressure, processing pressure) is not particularly limited, but is generally preferably 0.1 psi or more and 10 psi or less per unit area, more preferably 0.5 psi or more and 8 psi or less, and even more preferably 1 psi or more and 6 psi or less. Within this range, a high polishing rate can be achieved while further suppressing damage to the substrate due to the load and the occurrence of defects such as scratches on the surface. The rotation speed of the platen and the carrier are not particularly limited, but are generally preferably 10 rpm or more and 500 rpm or less, more preferably 20 rpm or more and 300 rpm or less, and even more preferably 30 rpm or more and 200 rpm or less. The method of supplying the polishing composition is also not particularly limited, and a method of continuously supplying the polishing composition using a pump or the like (flowing) may be used. The supply rate of the polishing composition (flow rate of the polishing composition) is not particularly limited as long as it covers the entire object to be polished, but is generally preferably 100 mL / min to 5000 mL / min. The polishing time is not particularly limited as long as it is appropriately set to obtain the desired polishing results, but is generally preferably 5 seconds to 180 seconds. Furthermore, polishing is preferably performed using in-situ dressing. Here, in-situ dressing refers to a technique in which the pad is dressed while polishing. In-situ dressing can further improve the uniformity of the polishing rate relative to the polishing time and further improve the controllability of polishing. A conditioner such as a diamond dresser is preferably used as the in-situ dressing member.

[0057] After polishing is complete, substrate 20 is washed with running water and dried using a spin dryer or the like to blow off any water droplets adhering to the substrate, yielding substrate 20 having the structure shown in Fig. 2B. As shown in Fig. 2B, substrate 20 processed by the polishing method of the present invention has a flat surface, and the upper surface of metal material 205 filled in the grooves of dielectric substrate 201 is coplanar with the upper surface of dielectric substrate 201.

[0058] Although the embodiments of the present invention have been described in detail, it should be understood that these are for purposes of explanation and example only and are not intended to be limiting, and that the scope of the present invention should be interpreted based on the appended claims.

[0059] The present invention includes the following aspects and embodiments.

[0060] 1. A polishing composition comprising an abrasive grain having a positive zeta potential, an oxidizing agent, a nitrogen-containing surfactant, a polishing rate enhancer, and an aqueous dispersion medium.

[0061] 2. The polishing composition according to the above item 1, wherein the pH value of the polishing composition is within the range of 2 to 4.

[0062] 3. The polishing composition according to claim 1, wherein the nitrogen-containing surfactant comprises an ammonium salt, an amine oxide, an amine, or any combination thereof.

[0063] 4. The polishing composition according to item 1 above, wherein the nitrogen-containing surfactant comprises a compound represented by one selected from the following chemical formulas:

[0064] [ka]

[0065] In the formula, R 1 , R 2 , R 3 , R 4 , R 5 each independently represents a C1-C20 alkyl group, and X represents a halogen atom.

[0066] 5. The polishing composition according to claim 1, wherein the abrasive grains are silica.

[0067] 6. The silanol group density on the surface of each silica is 1.0 to 6.0 / nm 2 6. The polishing composition according to 5 above, wherein

[0068] 7. The polishing composition according to 1 above, wherein the polishing rate enhancer is a nitrate.

[0069] 8. The polishing composition described in 1 above, wherein the oxidizing agent is periodic acid.

[0070] 9. The polishing composition according to 1 above, wherein the polishing composition contains 0.01 to 1 wt% of an oxidizing agent, 1 to 10 wt% of abrasive grains, 0.01 to 0.1 wt% of a nitrogen-containing surfactant, and 0.5 to 3 wt% of a polishing rate enhancer.

[0071] 10. A polishing method comprising the steps of preparing a polishing apparatus including a polishing pad and a polishing head, preparing a substrate between the polishing pad and the polishing head, and introducing the polishing composition between the substrate and the polishing pad, and then polishing the substrate.

[0072] 11. A polishing method as described in claim 10, wherein the substrate comprises a dielectric substrate having a first surface facing the polishing head and a second surface facing the polishing pad, and a metal material at least partially disposed on the second surface of the dielectric substrate.

[0073] 12. The polishing method according to claim 10, wherein the metal material is tungsten.

[0074] 13. The polishing method according to claim 10, wherein the substrate further comprises a liner layer disposed between the dielectric substrate and the metal material.

[0075] 14. The polishing method according to claim 13, wherein the liner layer comprises a metal nitride layer, a barrier film, or a combination thereof.

[0076] [Example] The present invention will be described in more detail below using examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Furthermore, unless otherwise specified, "%" and "parts" refer to "% by weight (wt%)" and "parts by weight," respectively.

[0077] <Preparation of Polishing Composition> The compounds used to prepare the polishing compositions in the examples and their properties are shown below. Colloidal silica A: Average primary particle size is 47 nm, average secondary particle size is 85 nm, zeta potential is positive, and silanol group density is 1.5 / nm 2 It is a colloidal silica solution. Colloidal silica B: Average primary particle size is 30 nm, average secondary particle size is 63 nm, zeta potential is positive, and silanol group density is 1.5 / nm 2 It is a colloidal silica solution. Colloidal silica C: average primary particle size 35 nm, average secondary particle size 65 nm, negative zeta potential, and silanol group density 5.7 / nm 2 It is a colloidal silica solution whose surface is modified with sulfonic acid. Colloidal silica D: Average primary particle size is 50 nm, average secondary particle size is 95 nm, zeta potential is positive, and silanol group density is 5.7 / nm 2 It is a colloidal silica solution whose surface is modified with aminopropyltriethoxysilane (APTES). Periodic acid: 50% orthoperiodic acid purchased from William Blythe Ltd. Ammonium nitrate: 50% ammonium nitrate purchased from Toyama Pharmaceutical Co., Ltd. Lauryl dimethyl amine oxide: purchased from Taiwan Shinnikko Co., Ltd. Product name: Tainolin LO. Polyoxyethylene lauryl amine: purchased from Takemoto Oil & Fat Co., Ltd. Product name: Pinonin D3110. Lauryltrimethylammonium chloride: purchased from Takemoto Oil & Fat Co., Ltd. Product name: Pinonin B111. Polyoxyethylene lauryl ether phosphate: purchased from Toho Chemical Industry Co., Ltd. Product name: PHOSPHANOL ML-220. Ammonium hydroxide (NH4OH): 29% ammonium hydroxide purchased from Taiwan Glass Co., Ltd. Tetraethylammonium hydroxide (TEAH): 35% tetraethylammonium hydroxide purchased from SACHEM, Inc.

[0078] Example 1 50 g of colloidal silica A (silica equivalent), 4.4 g of periodic acid, 11.27 g of ammonium nitrate, 0.25 g of lauryldimethylamine oxide, and 832.08 g of deionized water were placed in a 1000 mL beaker and mixed, and the pH value of the mixture was adjusted to 2.1 with ammonium hydroxide to obtain the polishing composition of Example 1. The polishing composition of Example 1 contains 5% of colloidal silica A (silica equivalent), 0.44% of periodic acid, 1.127% of ammonium nitrate, 0.045% of ammonium hydroxide, and 0.025% of lauryldimethylamine oxide.

[0079] (Examples 2 to 14 and Comparative Examples 1 to 7) Polishing compositions were prepared in the same manner as in Example 1, except that the abrasive grains, pH adjuster, nitrogen-containing surfactant, and pH were changed as shown in Tables 1 to 6.

[0080] [Table 1]

[0081] [Table 2]

[0082] [Table 3]

[0083] [Table 4]

[0084] [Table 5]

[0085] [Table 6]

[0086] <Polishing performance evaluation> (Preparing the object to be polished) The objects to be polished were silicon wafers (300 mm, blanket wafers) with a 4000 Å thick tungsten film or a 10000 Å thick silicon oxide film (specifically, silicon oxide derived from tetraethyl orthosilicate (TEOS); hereinafter, "oxide film") formed on the surface.

[0087] (polishing conditions) Polishing machine: Single-sided CMP polishing machine (manufactured by Ebara Corporation, product name: FREX 300E) Polishing pad: Polyurethane pad (Dow Electronic Materials, product name: IC1010) Grinding pressure: 3.2psi Platen rotation speed: 95pm Polishing head (carrier) rotation speed: 100 rpm Polishing composition flow rate: 200 ml / min Polishing time: 1 minute (Calculation of removal rate) The substrate thickness was measured before and after polishing using a sheet resistor (KLA-Tencor, product name: OmniMap RS-100) for tungsten and a KLA-Tencor, product name: ASET F5x for oxide, and the removal rate was calculated.

[0088] Using a viscometer (product name: Cannon-Fenske, manufactured by Shibata Scientific Co., Ltd.), the polishing compositions of Examples 1 to 15 and Comparative Examples 1 to 6 were left at 80°C for one week, and the viscosity change was measured to evaluate the stability of each polishing composition. If the viscosity change was 0 to 5%, the polishing composition was judged to have good stability (indicated by ◯); if the viscosity change was 5 to 10%, the polishing composition was judged to have slightly poor stability (indicated by △); and if the viscosity change was >10%, the polishing composition was judged to have poor stability (indicated by ×).

[0089] The removal rate and stability of each polishing composition measured by the above method are summarized in Table 7 below.

[0090] [Table 7]

[0091] <Research> As can be seen from the results in Table 7 above, the polishing compositions of Examples 1 to 14 were more stable than the polishing composition of Example 15. The polishing compositions of Examples 1 to 6 and 8 to 14 had a removal rate of 1600 Å / min or more for tungsten, the polishing compositions of Examples 1, 2, 5, 6, 8, and 9 to 15 had a removal rate of 1800 Å / min or more for tungsten, and the polishing compositions of Examples 8, 9, 11, and 12 had a removal rate of 2000 Å / min or more for tungsten. From this, it is clear that the polishing composition of the present invention has a higher removal rate for tungsten and a higher selectivity to other film species than the polishing compositions of Comparative Examples.

[0092] The features of the above-described embodiments are useful for those skilled in the art to understand the present invention. Those skilled in the art will understand that other processes and structures can be designed and modified based on the present invention to achieve the same purpose and / or the same advantages as those of the above-described embodiments. Those skilled in the art will also understand that such equivalent substitutions do not depart from the spirit and scope of the present invention, and that modifications, substitutions, or alterations can be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0093] 10: Method S101~S105: Step 20: Circuit board 201: Dielectric substrate 203: Liner layer 205: Metal materials

Claims

1. abrasive grains having a positive zeta potential; an oxidizing agent; a nitrogen-containing surfactant; A polishing speed enhancer; an aqueous dispersion medium; A polishing composition comprising: the abrasive grains are silica; The polishing composition, wherein the nitrogen-containing surfactant comprises at least one selected from the group consisting of lauryl dimethylamine oxide, lauryl trimethyl ammonium chloride, and polyoxyethylene lauryl amine.

2. The polishing composition described in claim 1, wherein the nitrogen-containing surfactant comprises at least one selected from the group consisting of lauryl dimethylamine oxide and lauryl trimethyl ammonium chloride.

3. 3. The polishing composition according to claim 1, wherein the pH value of the polishing composition is in the range of 2 to 4.

4. The silanol group density on the surface of each silica is 1.0 to 6.0 / nm ２ 4. The polishing composition according to claim 1, wherein

5. 5. The polishing composition according to claim 1, wherein the polishing rate enhancer is a nitrate.

6. 6. The polishing composition according to claim 5, wherein the nitrate is ammonium nitrate.

7. 7. The polishing composition according to claim 1, wherein the oxidizing agent is periodic acid.

8. 8. The polishing composition according to claim 1, wherein the oxidizing agent is 0.01 to 1 wt %, the abrasive grains are 1 to 10 wt %, the nitrogen-containing surfactant is 0.005 to 0.5 wt %, and the polishing rate enhancer is 0.5 to 3 wt %.

9. providing a polishing apparatus including a polishing pad and a polishing head; providing a substrate between the polishing pad and the polishing head; and A step of introducing the polishing composition according to any one of claims 1 to 8 between the substrate and the polishing pad, and then polishing the substrate; A polishing method comprising:

10. The substrate is a dielectric substrate having a first surface facing the polishing head and a second surface facing the polishing pad; a metallic material at least partially disposed on the second surface of the dielectric substrate; The polishing method according to claim 9 , comprising:

11. 11. The polishing method according to claim 10, wherein the metallic material is tungsten.

12. The polishing method according to claim 10 or 11, wherein the substrate further comprises a liner layer disposed between the dielectric substrate and the metal material.

13. The polishing method of claim 12 , wherein the liner layer comprises a metal nitride layer, a barrier film, or a combination thereof.

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