Acidified gypsum membrane grinding solution composition

Abstract

To provide a polishing liquid composition for silicon oxide films that improves the polishing rate of projections on the surface irregularities of a silicon oxide film while suppressing the polishing rate of the recesses.SOLUTION: A polishing liquid composition for silicon oxide films according to one embodiment includes: (component A) cerium oxide particles; (component B) a nitrogen-containing heterocyclic aromatic compound with at least one hydrogen atom in a nitrogen-containing heteroaromatic ring being substituted with a hydroxy group; (component C) a compound represented by the following formula (I) or (II); and an aqueous medium.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to a polishing solution composition for silicon oxide films, a method for manufacturing a semiconductor substrate using the same, and a polishing method. [Background technology]

[0002] Chemical mechanical polishing (CMP) is a technique that involves bringing the surface of a substrate to be polished into contact with a polishing pad, supplying polishing fluid to the contact area, and moving the substrate and polishing pad relative to each other. This process chemically reacts with the surface irregularities of the substrate and mechanically removes them, resulting in a flattened surface.

[0003] Currently, CMP (Chemical Polishing) technology is essential for semiconductor device manufacturing processes, including planarization of interlayer insulating films, formation of shallow trench element isolation structures, and formation of plugs and embedded metal wiring. In recent years, the multilayering and high-resolution of semiconductor devices have advanced dramatically, leading to a demand for further improvements in semiconductor device yield and throughput. Accordingly, there is a growing need for CMP processes that are free from polishing scratches and can be performed at higher speeds.

[0004] For example, Patent Document 1 proposes a CMP polishing solution with a pH of approximately 3 to 5, comprising an abrasive such as ceria, a self-stopping agent (e.g., benzoic acid), and an aqueous carrier. Patent Document 2 proposes a CMP composition comprising an abrasive such as cerium oxide, a removal rate accelerator (e.g., benzoic acid), and a solvent (e.g., water), with a pH greater than 5. Patent Document 3 proposes a polishing solution for CMP containing abrasive grains such as cerium oxide, a 4-pyrone compound, at least one compound selected from organic acids having an aromatic ring or pyridine ring and an acidic functional group (e.g., benzoic acid) and organic acids having an amino group, and water. Patent Document 4 proposes a polishing solution composition for silicon oxide films, which contains cerium oxide particles, a compound having a specific reduction potential, and an aqueous medium.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, in the field of semiconductors, high integration has been progressing, and there is a demand for more complex and finer wiring. Therefore, in CMP, by reducing the particle size of abrasive grains, defects are reduced. However, in this case, there is a problem that the polishing rate decreases, and an improvement in the polishing rate of the silicon oxide film is required. Particularly, in the planarization process of the interlayer insulating film of a 3D NAND type flash memory by CMP, since the step of the surface unevenness of the silicon oxide film is large between the array portion of the film stacked in a stepped manner on the polished substrate and its peripheral portion, there is a problem that it takes a long time for planarization by CMP. For example, in the reference International Conference on Planarization / CMP technology (ICPT), p106 (2016), as shown in FIG. 2, by performing an extra-etching process before CMP, a method of refining the convex portion, improving the CMP efficiency, and shortening the polishing time has been proposed. On the other hand, with the increase in the recording capacity, the thickness of the array portion is further improved, and the step of the surface unevenness becomes even larger. Therefore, it has become increasingly required to remove such fine convex portions at high speed. Also, suppression of polishing of the concave portion is required.

[0007] Therefore, the present disclosure provides a polishing liquid composition for a silicon oxide film, a method for manufacturing a semiconductor substrate using the same, a polishing method, etc., which can achieve both an improvement in the polishing rate of the convex portions and a suppression of the polishing rate of the concave portions on the surface unevenness of the silicon oxide film.

Means for Solving the Problems

[0008] In one aspect, the present disclosure relates to a polishing liquid composition for a silicon oxide film, which contains cerium oxide particles (Component A), a nitrogen-containing heteroaromatic compound in which at least one hydrogen atom of a nitrogen-containing heteroaromatic ring is substituted with a hydroxyl group (Component B), a compound represented by the following formula (I) or formula (II) (Component C), and an aqueous medium.

Chemical Formula

[0009] In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate, which includes a step of polishing a film to be polished using the polishing liquid composition for a silicon oxide film of the present disclosure.

[0010] In one aspect, the present disclosure relates to a polishing method, which includes a step of polishing a film to be polished using the polishing liquid composition of the present disclosure, and the film to be polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate.

Advantages of the Invention

[0011] According to this disclosure, in one embodiment, a polishing liquid composition for silicon oxide films can be provided that can achieve both improved polishing speed of convex portions and suppressed polishing speed of concave portions in the surface irregularities of the silicon oxide film. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram illustrating the evaluation wafer. [Figure 2] Figure 2 is a schematic diagram illustrating the extra etching of the interlayer insulating film of a 3D NAND flash memory before CMP (Chemical Polishing). [Modes for carrying out the invention]

[0013] Based on the results of diligent research by the present inventors, it is possible to achieve both improved polishing speed of the convex parts and suppressed polishing speed of the concave parts on the surface irregularities of a silicon oxide film by using a specific nitrogen-containing heteroaromatic compound (component B) and a specific compound (component C) in combination.

[0014] In other words, the present disclosure relates in one embodiment to a polishing liquid composition for silicon oxide films (hereinafter also referred to as "the polishing liquid composition of the present disclosure") which contains cerium oxide particles (component A), a nitrogen-containing heteroaromatic compound (component B) in which at least one hydrogen atom of a nitrogen-containing heteroaromatic ring is substituted with a hydroxyl group, a compound represented by formula (I) or formula (II) (component C), and an aqueous medium.

[0015] According to the polishing liquid composition of this disclosure, in one or more embodiments, it is possible to achieve both an improved polishing speed for the convex portions and a suppressed polishing speed for the concave portions of the silicon oxide film surface irregularities.

[0016] Although the details of the mechanism of action of this disclosure are not clear, it is presumed to be as follows. Component B reduces ceria particles, increasing the amount of trivalent cerium and thus improving the polishing speed. However, component B can also adsorb to the silicon oxide film being polished. As a result, when a small amount of component B is added, the reduction of cerium due to adsorption to ceria particles is dominant, leading to an improvement in polishing speed. However, as the amount of component B added increases, it tends to adsorb to the silicon oxide film as well, causing the polishing speed to decrease. From the viewpoint of polishing speed, it is preferable to suppress the polishing speed of recesses without increasing the amount of component B added. Therefore, it is desirable to enhance the protective ability of the polished object by component B with a component other than component B. In this disclosure, component C was identified from the viewpoint of interaction with component B. It is thought that component C enhances the protective ability of the polished object by interacting with component B, thereby suppressing the amount of recess polishing. On the other hand, since component C also adsorbs to component A, there is a concern that increasing the amount of component C added may impair dispersion stability. However, even without increasing the amount of component C added, the combined component B disperses and stabilizes component A, thereby suppressing the adsorption of component C onto component A. This promotes the adsorption of component C onto component B adsorbed on the object being polished, and thus enhances the protective ability of the object being polished. However, this disclosure does not have to be construed as being limited to these mechanisms.

[0017] [Polished film] The polishing liquid composition of this disclosure is, in one or more embodiments, a polishing liquid composition (polishing liquid composition for silicon oxide films) used for polishing silicon oxide films, and can be used in processes that require polishing of silicon oxide films. For example, in one or more embodiments, the polishing liquid composition of this disclosure can be used for polishing silicon oxide films in the process of forming element isolation structures of semiconductor substrates, polishing silicon oxide films in the process of forming interlayer insulating films, polishing silicon oxide films in the process of forming embedded metal wiring, or polishing silicon oxide films in the process of forming embedded capacitors. Furthermore, in one or more embodiments, the polishing liquid composition of this disclosure can be used in the manufacture of three-dimensional semiconductor devices such as three-dimensional NAND flash memory. In particular, the polishing liquid composition of this disclosure can be suitably used in one or more embodiments for polishing substrates having silicon oxide film protrusions. In one or more embodiments, the silicon oxide film protrusions are protrusions of a silicon oxide film on the substrate surface, such as protrusions with a width of 10 μm to 500 μm and a height of 4 μm to 10 μm. In one or more embodiments, the silicon oxide film protrusions can be formed by an extra-etching process before CMP of the interlayer insulating film of a three-dimensional NAND flash memory. In one or more embodiments, the silicon oxide film protrusions are silicon oxide film protrusions on the substrate surface after extra etching. In one or more embodiments, the substrate having silicon oxide film protrusions is a substrate that has been extra-etched before CMP of the interlayer insulating film of a three-dimensional NAND flash memory. In one or more embodiments, the polishing liquid composition of this disclosure is for polishing a substrate after extra etching.

[0018] [Cerium oxide particles (component A)] The polishing fluid composition of this disclosure contains cerium oxide (hereinafter also referred to as "ceria") particles (hereinafter simply referred to as "component A") as abrasive grains. Positively charged ceria or negatively charged ceria can be used as component A. The chargeability of component A can be confirmed, for example, by measuring the potential (surface potential) on the surface of the abrasive grains determined by electroacoustic method (ESA method: Electrokinetic Sonic Amplitude). The surface potential can be measured, for example, using a "Zeta Probe" (manufactured by Kyowa Interface Chemical Co., Ltd.), and specifically by the method described in the examples. Component A may be one type or a combination of two or more types. The chargeability of the abrasive grains is not limited, but positively charged ceria is preferred from the viewpoint of improving the polishing speed.

[0019] The manufacturing method, shape, and surface condition of component A are not particularly limited. Examples of component A include colloidal ceria, amorphous ceria, and ceria-coated silica. Colloidal ceria can be obtained by a build-up process, for example, by the methods described in Examples 1 to 4 of Japanese Patent Publication No. 2010-505735. Examples of amorphous ceria include pulverized ceria. One embodiment of pulverized ceria is calcined pulverized ceria obtained by calcining and pulverizing cerium compounds such as cerium carbonate and cerium nitrate. Another embodiment of pulverized ceria is single-crystal pulverized ceria obtained by wet pulverizing ceria particles in the presence of an inorganic acid or an organic acid. Examples of inorganic acids used in wet pulverization include nitric acid, and examples of organic acids include organic acids having a carboxyl group, specifically at least one selected from polycarboxylates such as ammonium polyacrylate, picolinic acid, glutamic acid, aspartic acid, aminobenzoic acid, and p-hydroxybenzoic acid. For example, when at least one selected from picolinic acid, glutamic acid, aspartic acid, aminobenzoic acid, and p-hydroxybenzoic acid is used in wet pulverization, positively charged ceria can be obtained, and when a polycarboxylate such as ammonium polyacrylate is used in wet pulverization, negatively charged ceria can be obtained. Examples of wet grinding methods include wet grinding using a planetary bead mill or the like. Examples of ceria-coated silica include composite particles having a structure in which at least a portion of the surface of silica particles is coated with granular ceria, as described in Examples 1 to 14 of Japanese Patent Publication No. 2015-63451 or Examples 1 to 4 of Japanese Patent Publication No. 2013-119131. These composite particles can be obtained, for example, by depositing ceria onto silica particles.

[0020] Examples of the shape of component A include a roughly spherical, polyhedral, or raspberry-like form.

[0021] From the perspective of improving the polishing rate, the average primary particle size of Component A is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, still more preferably 30 nm or more, still more preferably 50 nm or more, still more preferably 60 nm or more, still more preferably 70 nm or more. From the perspective of suppressing the occurrence of polishing scratches, it is preferably 300 nm or less, more preferably 200 nm or less, still more preferably 150 nm or less, still more preferably 100 nm or less, still more preferably 85 nm or less, still more preferably 80 nm or less. In the present disclosure, the average primary particle size of Component A is calculated using the BET (nitrogen adsorption) specific surface area S (m 2 / g) calculated by the BET method. The BET specific surface area can be measured by the method described in the examples.

[0022] From the perspective of achieving both an improvement in the polishing rate of the convex portions and suppression of the polishing rate of the concave portions in the surface unevenness of the silicon oxide film, the content of Component A in the polishing liquid composition of the present disclosure is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more. From the perspective of suppressing the occurrence of polishing scratches, it is preferably 6% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, still more preferably 0.5% by mass or less, still more preferably 0.4% by mass or less. More specifically, the content of Component A in the polishing liquid composition of the present disclosure is preferably 0.001% by mass or more and 6% by mass or less, more preferably 0.01% by mass or more and 3% by mass or less, still more preferably 0.05% by mass or more and 1% by mass or less, still more preferably 0.1% by mass or more and 0.5% by mass or less, still more preferably 0.2% by mass or more and 0.4% by mass or less. When Component A is a combination of two or more types, the content of Component A refers to the total content thereof.

[0023] [Nitrogen-containing heteroaromatic compound (Component B)] The polishing fluid composition of this disclosure contains a nitrogen-containing heteroaromatic compound (hereinafter also simply referred to as "component B") in which at least one hydrogen atom of a nitrogen-containing heteroaromatic ring is substituted with a hydroxyl group. From the viewpoint of achieving both improved polishing speed of the convex parts and suppressed polishing speed of the concave parts on the surface irregularities of the silicon oxide film, component B is preferably at least one compound selected from N-oxide compounds containing a nitrogen-containing heteroaromatic ring skeleton in which at least one hydrogen atom is substituted with a hydroxyl group, and salts thereof. Examples of the salts include alkali metal salts, alkaline earth metal salts, organic amine salts, ammonium salts, etc. Component B may be one type or a combination of two or more types.

[0024] In this disclosure, the term "N-oxide compound" refers to a compound having an N-oxide group (N→O group) in one or more embodiments. An N-oxide compound may have one or more N→O groups, and from the viewpoint of availability, one N→O group is preferred.

[0025] In this disclosure, at least one nitrogen atom contained in the nitrogen-containing heteroaromatic ring skeleton forms an N-oxide. In one or more embodiments, the nitrogen-containing heteroaromatic ring contained in component B is a monocyclic or bicyclic fused ring. In one or more embodiments, the number of nitrogen atoms in the nitrogen-containing heteroaromatic ring contained in component B is 1 to 3, with 1 or 2 being preferred and 1 being more preferred from the viewpoint of improving polishing speed. In one or more embodiments, the nitrogen-containing heteroaromatic ring skeleton contained in component B is a pyridine N-oxide skeleton, etc. In this disclosure, the pyridine N-oxide skeleton has a configuration in which the nitrogen atoms contained in the pyridine ring form an N-oxide.

[0026] As component B, in one or more embodiments, an N-oxide compound or a salt thereof is preferred, from the viewpoint of achieving both improved polishing speed of the convex parts and suppressed polishing speed of the concave parts on the surface irregularities of the silicon oxide film. The pyridine ring has at least one hydrogen atom of the pyridine ring substituted with a hydroxyl group.

[0027] Examples of component B include 2-hydroxypyridine N-oxide or its salts.

[0028] The content of component B in the polishing liquid composition of this disclosure is preferably 0.1 mM or more, more preferably 1 mM or more, and even more preferably 1.5 mM or more, from the viewpoint of improving the polishing speed of protrusions and suppressing polishing of recesses, and preferably 10 mM or less, more preferably 7.5 mM or less, even more preferably 5 mM or less, and even more preferably 3 mM or less, from the viewpoint of improving the polishing speed of protrusions. More specifically, the content of component B in the polishing liquid composition of this disclosure is preferably 0.1 mM or more and 10 mM or less, more preferably 1 mM or more and 7.5 mM or less, even more preferably 1.5 mM or more and 5 mM or less, and even more preferably 1.5 mM or more and 3 mM or less. When component B is a combination of two or more types, the content of component B refers to the total content of those types.

[0029] [Compound represented by formula (I) or formula (II) (component C)] The polishing fluid composition of this disclosure contains a compound represented by the following formula (I) or formula (II) (hereinafter also simply referred to as "component C"). Component C is a compound that does not have a hydroxyl group. However, the hydroxyl group (-OH) does not include the OH of a carboxyl group (-COOH). Component C may be one type or a combination of two or more types. [ka]

[0030] In equation (I) above, R 1 R represents an aliphatic hydrocarbon group having 1 to 6 carbon atoms. 2 This represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 6 carbon atoms, M 1 This includes hydrogen atoms, alkali metals, organic cations, or ammonium (NH4) + ) indicates. In the above equation (I), R 1From the viewpoint of achieving both improved polishing speed of the convex parts and suppressed polishing speed of the concave parts on the surface irregularities of the silicon oxide film, alkyl groups having 1 to 4 carbon atoms are preferred, and from the viewpoint of water solubility, alkyl groups having 1 to 2 carbon atoms are more preferred. 2 From a similar viewpoint, hydrogen atoms or alkyl groups having 1 to 4 carbon atoms are preferred, and hydrogen atoms are more preferred. 1 From a similar viewpoint, at least one selected from hydrogen atoms and alkali metal ions is preferred, and hydrogen atoms are more preferred. Examples of organic cations include organic ammonium compounds in one or more embodiments, such as alkylammonium compounds like tetramethylammonium, tetraethylammonium, and tetrabutylammonium.

[0031] In the above equation (II), R 3 and R 4 n represents a hydrogen atom, hydrocarbon group, methoxy group, or ethoxy group, either identical or different, n represents 0 or 1, m represents 0 or 1, M 2 This includes hydrogen atoms, alkali metals, organic cations, or ammonium (NH4) + ) indicates. In the above equation (II), R 3 and R 4 From the viewpoint of achieving both improved polishing speed of the convex parts and suppressed polishing speed of the concave parts on the surface irregularities of the silicon oxide film, the following are preferred: a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, a methoxy group, or an ethoxy group; a hydrogen atom or a methoxy group is more preferred; and a hydrogen atom is even more preferred. From the same viewpoint, n is preferably 0. From the same viewpoint, m is preferably 0. 2 From a similar perspective, hydrogen atoms, alkali metal ions, or ammonium (NH4) + ) is preferred, and hydrogen atoms or ammonium (NH4 + ) is preferred. Examples of organic cations include organic ammonium in one or more embodiments, such as alkylammonium such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium.

[0032] Component C can be, for example, at least one selected from benzoic acid or its salt, methoxyacetic acid or its salt, ethoxyacetic acid or its salt, and phenoxyacetic acid or its salt. Among these, benzoic acid or its salt is preferred from the viewpoint of achieving both improved polishing speed of the convex parts and suppressed polishing speed of the concave parts on the surface irregularities of the silicon oxide film.

[0033] The pKa of component C is preferably greater than 3.5, more preferably 3.6 or higher, and even more preferably 3.7 or higher, from the viewpoint of dispersion stability and polishing properties, and similarly, preferably less than 4.6, more preferably 4.4 or lower, and even more preferably 4.2 or lower. More specifically, the pKa of component C is preferably greater than 3.5 and less than 4.6, more preferably 3.6 or higher and 4.4 or lower, and even more preferably 3.7 or higher and 4.2 or lower. The pKa of component C can be measured, for example, by the method described in the examples.

[0034] The content of component C in the polishing liquid composition of this disclosure is preferably 0.1 mM or more, more preferably 0.7 mM or more, and even more preferably 1.3 mM or more, from the viewpoint of suppressing the polishing of recesses, and preferably 5 mM or less, more preferably 4.5 mM or less, and even more preferably 4 mM or less, from the viewpoint of improving the polishing speed of protrusions. More specifically, the content of component C in the polishing liquid composition of this disclosure is preferably 0.1 mM or more and 5 mM or less, more preferably 0.7 mM or more and 4.5 mM or less, and even more preferably 1.3 mM or more and 4 mM or less. When component C is a combination of two or more types, the content of component C refers to the total content of those types.

[0035] Components in the polishing liquid composition disclosed herein B Ingredients in relation to the content C Molar ratio of the content C / B From the viewpoint of improving the polishing speed of protrusions, a molar ratio of 0.2 or higher is preferred, more preferably 0.5 or higher, and even more preferably 0.7 or higher. From the viewpoint of suppressing the polishing of recesses, a molar ratio of 4 or lower is preferred, more preferably 3 or lower, and even more preferably 1.5 or lower. More specifically, the molar ratio in the polishing liquid composition of this disclosure. C / BThe value is preferably 0.2 to 4, more preferably 0.5 to 3, and even more preferably 0.7 to 1.5.

[0036] [Aqueous medium] Examples of aqueous media included in the polishing fluid composition of this disclosure include water such as distilled water, ion-exchanged water, pure water, and ultrapure water, or a mixed solvent of water and a solvent. Examples of the solvent include solvents that can be mixed with water (for example, alcohols such as ethanol). When the aqueous media is a mixed solvent of water and a solvent, the proportion of water to the total mixed media is not particularly limited as long as the effects of this disclosure are not hindered. From an economic standpoint, for example, 95% by mass or more is preferred, 98% by mass or more is more preferred, and less than 100% by mass is preferred. From the viewpoint of surface cleanliness of the substrate to be polished, water is preferred as the aqueous media, ion-exchanged water and ultrapure water are more preferred, and ultrapure water is even more preferred. The content of the aqueous medium in the polishing fluid composition of this disclosure may be the remainder after excluding component A, component B, component C, and any optional components described later that may be added as needed.

[0037] [Optional ingredients] The polishing liquid composition of this disclosure may further contain any components such as pH adjusters, surfactants, thickeners, dispersants, rust inhibitors, preservatives, basic substances, polishing speed enhancers, silicon nitride film polishing inhibitors, and polysilicon film polishing inhibitors.

[0038] In one or more embodiments, the polishing fluid composition of the present disclosure preferably contains substantially no 4-pyrone compounds from the viewpoint of preservation. For example, the content of 4-pyrone compounds in the polishing fluid composition of the present disclosure is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0% by mass.

[0039] [Polishing liquid composition] The polishing fluid composition of this disclosure can be manufactured by a manufacturing method comprising the steps of blending component A, component B, component C, an aqueous medium, and optionally any other component in a known manner. For example, the polishing fluid composition of this disclosure may consist of a dispersion (slurry) containing component A and an aqueous medium, a solution containing component B, component C, and an aqueous medium, and optionally any other component. In this disclosure, "blending" includes mixing component A, component B, component C, and an aqueous medium, and optionally any other component, simultaneously or sequentially. The order of mixing is not particularly limited. The blending can be carried out, for example, using a mixer such as a homomixer, homogenizer, ultrasonic disperser, and wet ball mill. The amount of each component blended in the manufacturing method of the polishing fluid composition of this disclosure may be the same as the content of each component in the polishing fluid composition of this disclosure described above.

[0040] Embodiments of the polishing fluid composition of this disclosure may be a so-called one-component type, in which all components are supplied to the market in a pre-mixed state, or a so-called two-component type, in which the components are mixed at the time of use. For example, in one or more embodiments, a two-component polishing fluid composition may consist of a first liquid containing component A and a second liquid containing components B and C, in which the first and second liquids are mixed at the time of use. The mixing of the first and second liquids may be performed before supplying them to the surface to be polished, or they may be supplied separately and mixed on the surface of the substrate to be polished. The first and second liquids may each contain the above-mentioned optional components as needed.

[0041] The pH of the polishing liquid composition of this disclosure is preferably 3.5 or higher, more preferably 4 or higher, and even more preferably 4.5 or higher, from the viewpoint of achieving both improved polishing speed of the convex parts and suppression of the polishing speed of the concave parts on the surface irregularities of the silicon oxide film, and similarly preferably 7.5 or lower, more preferably 6.5 or lower, and even more preferably 5.5 or lower. More specifically, the pH of the polishing liquid composition of this disclosure is preferably 3.5 or higher and 7.5 or lower, more preferably 4 or higher and 6.5 or lower, and even more preferably 4.5 or higher and 5.5 or lower. In this disclosure, the pH of the polishing liquid composition is the value at 25°C and is the value measured using a pH meter. Specifically, the pH of the polishing liquid composition of this disclosure can be measured by the method described in the examples.

[0042] In this disclosure, "content of each component in the polishing liquid composition" means the content of each component at the time of polishing, that is, at the time when the polishing liquid composition is first used for polishing. The content of each component in the polishing liquid composition of this disclosure can be considered, in one or more embodiments, as the amount of each component blended in the polishing liquid composition of this disclosure. The polishing fluid composition of this disclosure may be stored and supplied in a concentrated state, provided that its stability is not compromised. This is preferable because it reduces manufacturing and transportation costs. This concentrated solution can then be used in the polishing process after being appropriately diluted with the aforementioned aqueous medium as needed. A dilution ratio of 5 to 100 times is preferred.

[0043] [Polishing solution kit] In one embodiment, this disclosure relates to a kit for preparing the polishing fluid composition of this disclosure (hereinafter also referred to as the "polishing fluid kit of this disclosure"). An example of a polishing fluid kit according to this disclosure is a polishing fluid kit (two-component polishing fluid composition) which contains, for example, an abrasive dispersion (first liquid) containing component A and an aqueous medium, and an additive aqueous solution (second liquid) containing component B and component C, in an unmixed state, and which is mixed at the time of use and diluted with an aqueous medium as necessary. The aqueous medium contained in the abrasive dispersion (first liquid) may be the entire amount or a part of the aqueous medium used to prepare the polishing fluid composition. The additive aqueous solution (second liquid) may contain a part of the aqueous medium used to prepare the polishing fluid composition. The abrasive dispersion (first liquid) and the additive aqueous solution (second liquid) may each contain the above-mentioned optional components as necessary. The mixing of the abrasive dispersion (first liquid) and the additive aqueous solution (second liquid) may be performed before supplying them to the surface to be polished, or they may be supplied separately and mixed on the surface of the substrate to be polished. According to the polishing fluid kit of this disclosure, a polishing fluid composition capable of improving the polishing speed of silicon oxide films can be obtained.

[0044] [Polishing method] This disclosure relates to a polishing method (hereinafter also referred to as the polishing method of this disclosure) that, in one embodiment, includes the step of polishing a film to be polished using the polishing liquid composition of this disclosure, wherein the film to be polished is a silicon oxide film formed in the manufacturing process of a semiconductor substrate. Examples of the film to be polished include the film to be polished in the polishing liquid composition of this disclosure as described above. For example, in one or more embodiments, the film to be polished in the polishing method of this disclosure is a silicon oxide film protrusion on the substrate surface after extra etching. In one or more embodiments, the polishing method of this disclosure includes the step of polishing a substrate to be polished using the polishing liquid composition of this disclosure. Examples of the substrate to be polished include a substrate after extra etching and a substrate having silicon oxide film protrusions. By using the polishing method of this disclosure, it is possible to achieve both improved polishing speed of the protrusions and suppressed polishing speed of the recesses in the surface irregularities of the silicon oxide film, thereby improving the productivity of semiconductor substrates with improved quality. The polishing method and conditions in the polishing method of this disclosure can be the same as those for the semiconductor substrate manufacturing method of this disclosure described later.

[0045] [Manufacturing method for semiconductor substrates] This disclosure relates to a method for manufacturing a semiconductor substrate (hereinafter also referred to as "the semiconductor substrate manufacturing method of this disclosure") which, in one embodiment, includes a step of polishing a film to be polished using the polishing liquid composition of this disclosure (polishing step). Examples of the film to be polished include the film to be polished in the polishing liquid composition of this disclosure as described above. For example, in one or more embodiments, the film to be polished in the semiconductor substrate manufacturing method of this disclosure is the silicon oxide film protrusions on the substrate surface after extra etching. The semiconductor substrate manufacturing method of this disclosure includes, in one or more embodiments, a step of polishing a substrate to be polished using the polishing liquid composition of this disclosure. Examples of the substrate to be polished include a substrate after extra etching, a substrate having silicon oxide film protrusions, etc. According to the semiconductor substrate manufacturing method of this disclosure, it is possible to achieve both an improvement in the polishing speed of the protrusions on the surface irregularities of the silicon oxide film and a suppression in the polishing speed of the recesses, thereby enabling the efficient manufacture of semiconductor substrates with improved quality.

[0046] As a specific example of the semiconductor substrate manufacturing method of this disclosure, first, a silicon dioxide film is alternately laminated on a silicon substrate, and then a silicon nitride (Si3N4) film is alternately laminated on the silicon dioxide layer. Subsequently, channels are formed using polysilicon, the laminated films are trimmed, a charge trap layer is formed, and a tungsten (W) gate is formed to form an array. Then, silicon dioxide layers are laminated on the array by CVD (chemical vapor deposition) or the like. The silicon dioxide film formed in this way has a large step difference between the array portion and the peripheral portion. Next, the silicon dioxide film in the array portion is polished by CMP until it is the same height as the peripheral portion. As shown in Figure 2, a method has been proposed in which the protrusions are refined, the CMP efficiency is improved, and the polishing time is shortened by performing an extra-etching process before CMP. The polishing liquid compositions of this disclosure can be suitably used in one or more embodiments for polishing substrates having silicon oxide film protrusions after extra etching. In one or more embodiments, the silicon oxide film protrusions are protrusions of the silicon oxide film on the substrate surface, and examples include protrusions with a width of 10 μm to 500 μm and a height of 4 μm to 10 μm.

[0047] In polishing by CMP, the surface of the substrate to be polished and the polishing pad are in contact, and the polishing liquid composition of this disclosure is supplied to these contact areas while the substrate and the polishing pad are moved relative to each other, thereby flattening the uneven surface of the substrate to be polished.

[0048] In the polishing process, the rotation speed of the polishing pad is, for example, 30 to 200 rpm / min, the rotation speed of the substrate to be polished is, for example, 30 to 200 rpm / min, and the polishing load set on the polishing apparatus equipped with the polishing pad is, for example, 20 to 500 g-force / cm². 2 The supply rate of the polishing solution composition can be set to, for example, 10 to 500 mL / min or less. If the polishing solution composition is a two-component polishing solution composition, the polishing speed of the film to be polished can be adjusted by adjusting the supply rate (or supply amount) of the first liquid and the second liquid, respectively.

[0049] In the polishing process described above, the polishing speed of the film to be polished (silicon oxide film) is preferably 50 nm / min or more, more preferably 80 nm / min or more, and even more preferably 90 nm / min or more, from the viewpoint of improving productivity. [Examples]

[0050] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited in any way by these examples.

[0051] 1. Preparation of polishing solution composition [Preparation of polishing solution compositions for Examples 1-14 and Comparative Examples 1-12] Abrasive liquid compositions for Examples 1-14 and Comparative Examples 1-12 were obtained by mixing cerium oxide particles (component A), nitrogen-containing heteroaromatic compounds shown in Table 2 (component B), compounds shown in Table 1 (component C or non-component C), and water. The amount (content) (mass % or mM, effective content) of each component in the abrasive liquid composition is as shown in Table 2, and the water content is the residue after removing component A, component B, and component C or non-component C. pH adjustment was performed using ammonia or nitric acid.

[0052] The following were used for component A, component B, component C, and non-component C. (Component A) Calcined and ground ceria [Average primary particle size: 80 nm, BET specific surface area: 25 m²] 2 / g, surface potential=80mV] (Component B) 2-Hydroxypyridine N-oxide (manufactured by Tokyo Chemical Industry Co., Ltd.) (Component C) C1: Ammonium benzoate (manufactured by Yoneyama Chemical Industries, Ltd.) [In formula (II), R 3 =H, R 4 =H, n=0, m=0, M 2 =NH4 + That is the case. C2: Methoxyacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (I), R 1 =CH3, R 2 =H, M 1 =H. C3: Ethoxyacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (I), R 1 =C2H2, R 2 =H, M 1 =H. C4: Phenoxyacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (II), R 3 =H, R 4 =H, n=1, m=1, M 2 =H. C5: Benzoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (II), R 3 =H, R 4 =H, n=0, m=0, M 2 =H. C6: p-Anisic acid (4-methoxybenzoic acid, manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (II), R 3 =CH3O, R 4 =H, n=0, m=0, M 2 =H. (Non-ingredient C) C7: Acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) C8: Glycolic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) C9: Butyric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) C10: Cyclohexanecarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) C11: Salicylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) C12: p-Hydroxybenzoic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) C13:3,5-Dihydroxybenzoic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) C14: Acetylsalicylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0053] [Table 1]

[0054] 2. Measurement methods for various parameters [Average primary particle size of cerium oxide particles (component A)] The average primary particle size (nm) of cerium oxide particles is calculated using the specific surface area S(m²) of the BET (nitrogen adsorption) method. 2 This refers to the particle size (converted to a perfect sphere) calculated using the following formula ( / g), and is calculated using the following formula. In the formula below, the specific surface area S was determined by crushing 10 g of cerium oxide particle slurry in an agate mortar after removing moisture by vacuum drying at 110°C, and then measuring the resulting powder using a flow-type automatic specific surface area measuring device, FlowSorb 2300 (manufactured by Shimadzu Corporation). Average primary particle diameter (nm)=820 / S

[0055] [Surface potential of cerium oxide (component A)] The surface potential (mV) of cerium oxide particles was measured using a surface potential measuring device (Zeta Probe, manufactured by Kyowa Interface Chemical Co., Ltd.). Ultrapure water was used to adjust the cerium oxide concentration to 0.3%, which was then placed in the surface potential measuring device. The surface potential was measured under conditions of a particle density of 7.13 g / ml and a particle dielectric constant of 7. Three measurements were performed, and the average value was used as the measurement result.

[0056] [pKa of compound (component C or non-component C)] The pKa of the compound (component C or non-component C) was measured using a potentiometric automatic titrator (KEM "AT-710M / S"). After diluting the compound with ultrapure water to various concentrations (0.01M to 1M) according to its water solubility, the compound was titrated with a 0.01 to 0.1M sodium hydroxide solution (Fujifilm Wako Pure Chemical Industries, Ltd.) at room temperature while stirring, and the pKa was derived from the neutralization titration curve.

[0057] [pH of the polishing solution composition] The pH value of the polishing solution composition at 25°C was measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and the value was obtained 1 minute after immersion of the electrode in the polishing solution composition. The results are shown in Table 2.

[0058] 3. Evaluation of polishing liquid compositions (Examples 1-14 and Comparative Examples 1-12) [Evaluation sample] As an evaluation sample, the wafer (200 mm in diameter) shown in Figure 1 was used. This evaluation sample had a 6 μm thick silicon oxide film formed on a silicon substrate, and then dry etching created a grid-like pattern of raised and recessed areas, as shown in Figure 1. Each recess measures 20 mm (length) x 20 mm (width) x 4 μm (depth). The silicon oxide film was formed using P-TEOS. This evaluation sample is a model substrate for a substrate with silicon oxide film protrusions after extra etching.

[0059] [Polishing conditions] Polishing equipment: Single-sided polishing machine [Ebara Corporation, FREX-200] Polishing pad: Hard urethane pad "IC-1000 / Suba400" [manufactured by Nitta Haas Co., Ltd.] Plate rotation speed: 100 rpm Head rotation speed: 107 rpm Grinding load: 280 hPa Polishing liquid supply amount: 200mL / min Polishing time: 1 minute

[0060] [Polishing speed for raised areas] The evaluation samples were polished under the above polishing conditions using the polishing solution compositions of Examples 1-14 and Comparative Examples 1-3, 5-7, and 10. Comparative Examples 4, 8, 9, 11, and 12 could not be tested due to aggregation of the polishing solution. The thickness of the silicon oxide film on the 500 μm wide protrusions of the wiring was measured before and after polishing using an ASET-F5X (manufactured by KLA). The polishing speed of the protrusions was calculated using the following formula, and the results are shown in Table 2. Polishing speed of the protrusion = [Silicon oxide film thickness of the protrusion before polishing (nm) - Silicon oxide film thickness of the protrusion after polishing (nm)] / Polishing time (minutes)

[0061] [Polishing speed for recessed areas] The evaluation samples were polished under the above polishing conditions using the polishing solution compositions of Examples 1-14 and Comparative Examples 1-3, 5-7, and 10. Comparative Examples 4, 8, 9, 11, and 12 could not be tested due to aggregation of the polishing solution. The thickness of the silicon oxide film in the center of a 20 mm square recess before and after polishing was measured using an ASET-F5X (manufactured by KLA). The recess polishing speed was calculated using the following formula, and the results are shown in Table 2. Polishing speed of recessed area = [Silicon oxide film thickness of recessed area before polishing (nm) - Silicon oxide film thickness of recessed area after polishing (nm)] / Polishing time (minutes)

[0062] [Polishing speed ratio (polishing selectivity)] The ratio of the polishing speed of the convex portion to the polishing speed of the concave portion was defined as the polishing speed ratio (convex portion / concave portion) and was calculated using the following formula. A larger value for the polishing speed ratio (convex portion / concave portion) indicates higher polishing selectivity. Polishing speed ratio = Polishing speed of convex parts (nm / min) / Polishing speed of concave parts (nm / min) The results are shown in Table 2.

[0063] [Table 2]

[0064] As shown in Table 2, the polishing liquid compositions of Examples 1 to 14 were found to achieve both improved polishing speed on the convex parts and suppressed polishing speed on the concave parts of the silicon oxide film surface irregularities compared to Comparative Examples 1 to 3, 5 to 7, and 10. The polishing liquid compositions of Comparative Examples 4, 8, 9, 11, and 12 could not be evaluated due to the formation of sediment. [Industrial applicability]

[0065] The polishing liquid composition relating to this disclosure is useful in a method for manufacturing semiconductor devices for high density or high integration.

Claims

1. The material contains cerium oxide particles (component A), a nitrogen-containing heteroaromatic compound (component B) in which at least one hydrogen atom of a nitrogen-containing heteroaromatic ring is substituted with a hydroxyl group, a compound represented by the following formula (I) or formula (II) (component C), and an aqueous medium. The molar ratio of the content of component C to the content of component B, C / B, is 0.2 or more and 4 or less, A polishing solution composition for silicon oxide films that does not contain 4-pyrone compounds. 【Chemistry 1】 In the above formula (I), R 1 R represents an aliphatic hydrocarbon group having 1 to 6 carbon atoms. 2 This represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 6 carbon atoms, M 1 is a hydrogen atom, alkali metal, organic cation or ammonium (NH 4 + ) indicates. In the formula (II), R 3 and R 4 are the same or different and each represents a hydrogen atom, a hydrocarbon group, a methoxy group, or an ethoxy group, n represents 0 or 1, m represents 0 or 1, and M 2 represents a hydrogen atom, an alkali metal, an organic cation or ammonium (NH 4 + ).

2. The polishing liquid composition according to claim 1, wherein component B is an N-oxide compound or a salt thereof having a pyridine ring in which at least one hydrogen atom of the pyridine ring is substituted with a hydroxyl group.

3. The polishing liquid composition according to claim 1 or 2, wherein component B is 2-hydroxypyridine N-oxide or a salt thereof.

4. The polishing liquid composition according to any one of claims 1 to 3, wherein the pKa of component C is greater than 3.5 and less than 4.

6.

5. The polishing liquid composition according to any one of claims 1 to 4, wherein component C is at least one selected from benzoic acid or a salt thereof, methoxyacetic acid or a salt thereof, ethoxyacetic acid or a salt thereof, and phenoxyacetic acid or a salt thereof.

6. The polishing liquid composition according to any one of claims 1 to 5, wherein the content of component C is 0.1 mM or more and 5 mM or less.

7. The polishing liquid composition according to any one of claims 1 to 6, wherein the pH of the polishing liquid composition is 3.5 or more and 7.5 or less.

8. A method for manufacturing a semiconductor substrate, comprising the step of polishing a film to be polished using a polishing liquid composition according to any one of claims 1 to 7.

9. A polishing method comprising the step of polishing a film to be polished using a polishing liquid composition according to any one of claims 1 to 7, wherein the film to be polished is a silicon oxide film formed in the manufacturing process of a semiconductor substrate.

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