Polishing liquid composition for silicon oxide film
Patent Information
- Application Number
- JP2022165767
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-10-14
- Publication Date
- 2025-09-30
Smart Images
Figure 2024058420000001
Abstract
Description
[Technical field]
[0001] The present disclosure relates to a polishing composition for silicon oxide films, and a method for producing and polishing semiconductor substrates using the same. [Background technology]
[0002] Chemical mechanical polishing (CMP) is a technique in which the surface of the substrate to be polished is brought into contact with a polishing pad, and a polishing liquid is supplied to the contact point while the substrate and polishing pad are moved relative to each other, thereby chemically reacting with and mechanically removing and planarizing the uneven surface of the substrate.
[0003] Currently, CMP technology is essential in the manufacturing process of semiconductor devices for flattening interlayer insulating films, forming shallow trench isolation structures, forming plugs and buried metal wiring, etc. In recent years, semiconductor devices have become increasingly multi-layered and highly precise, and there is a demand for further improvements in the yield and throughput of semiconductor devices. Accordingly, there is a demand for scratch-free and faster polishing in the CMP process.
[0004] For example, Patent Document 1 proposes a method for producing cerium dioxide particles, comprising the steps of: a) providing an aqueous reaction mixture containing a cerous ion source, a hydroxide ion source, at least one nanoparticle stabilizer, and an oxidizing agent; b) mechanically shearing the mixture to thereby form a suspension of cerium hydroxide nanoparticles; and c) heating the mixture to a temperature between 50° C. and 100° C. to thereby form cerium dioxide nanoparticles, wherein the nanoparticle stabilizer is selected from the group consisting of alkoxy-substituted carboxylic acids, α-hydroxyl carboxylic acids, pyruvic acid, and small organic polyacids. Paragraph 0204 of the same document describes that the cerium dioxide particles can be used as an abrasive for planarizing semiconductor substrates. Patent Document 2 proposes a polishing liquid for polishing a barrier layer of a semiconductor integrated circuit, the polishing liquid containing colloidal silica whose surface exhibits a positive ζ potential, a compound having a carboxyl group, a corrosion inhibitor, and a surfactant, and having a pH of 2.5 to 5.0. [Prior art documents] [Patent documents]
[0005] [Patent Document 1] JP 2014-139127 A [Patent Document 2] JP 2008-181954 A Summary of the Invention [Problem to be solved by the invention]
[0006] In recent years, the semiconductor industry has become highly integrated, and there is a demand for more complex and finer wiring. For this reason, in CMP, the grain size of the abrasive is reduced to reduce defects, but this causes a problem of a decrease in the polishing speed, and there is a demand for an improvement in the polishing speed of silicon oxide films. In particular, in the planarization process of the interlayer insulating film of a 3D NAND flash memory by CMP, there is a problem that the difference in the surface unevenness of the silicon oxide film between the array part of the film stacked in a stepped manner on the polished substrate and its surrounding area is large, so that planarization by CMP takes a long time. For example, the reference International Conference on Planarization / CMP technology (ICPT), p106 (2016) proposes a method of miniaturizing the convex parts, improving the CMP efficiency, and shortening the polishing time by performing an extra-etching process before CMP as shown in Figure 1. On the other hand, with the increase in recording capacity, the thickness of the array part is further increased, and the difference in the surface unevenness becomes even larger. Therefore, it is becoming increasingly necessary to remove such fine convex parts at high speed. In addition, after removing the fine protrusions, the entire substrate surface is further scraped off to flatten the substrate surface. However, the polishing speed may differ between the center and the periphery of the substrate surface, which causes a problem of reduced in-plane polishing uniformity (global flattening). Therefore, it is required to improve the in-plane polishing uniformity at a high polishing speed.
[0007] Therefore, the present disclosure provides a polishing composition for silicon oxide films that can improve both the polishing rate of silicon oxide films and the in-plane polishing uniformity, and a manufacturing method and polishing method for semiconductor substrates that use the same. [Means for solving the problem]
[0008] In one aspect, the present disclosure relates to a polishing liquid composition for silicon oxide films, which contains cerium oxide particles (component A), an alkoxyacetic acid represented by the following formula (I) or a salt thereof (component B), and an aqueous medium. [ka] In the formula (I), R represents an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an organic cation, or ammonium (NH4 + ) is shown.
[0009] In one aspect, the present disclosure relates to a method for producing a semiconductor substrate, comprising a step of polishing a film to be polished with the polishing liquid composition for silicon oxide film of the present disclosure.
[0010] In one aspect, the present disclosure relates to a polishing method comprising a step of polishing a film to be polished with the polishing liquid composition of the present disclosure, wherein the film to be polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate. Effect of the Invention
[0011] According to one aspect of the present disclosure, it is possible to provide a polishing composition for silicon oxide films that can improve both the polishing rate of a silicon oxide film and the in-plane polishing uniformity. [Brief description of the drawings]
[0012] [Figure 1] FIG. 1 is a schematic diagram for explaining extra etching before CMP of an interlayer insulating film of a 3D NAND flash memory. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] The present inventors have conducted extensive research and have discovered that by adding a specific alkoxyacetic acid or a salt thereof (component B) to a polishing composition containing cerium oxide particles (component A), it is possible to improve both the polishing rate of a silicon oxide film and the in-plane uniformity of the polishing.
[0014] That is, in one aspect, the present disclosure relates to a polishing liquid composition for silicon oxide films (hereinafter also referred to as the "polishing liquid composition of the present disclosure") that contains cerium oxide particles (component A), an alkoxyacetic acid represented by the above formula (I) or a salt thereof (component B), and an aqueous medium. [ka] In the formula (I), R represents an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an organic cation, or ammonium (NH4 + ) is shown.
[0015] According to the polishing composition of the present disclosure, in one or a plurality of embodiments, it is possible to improve both the polishing rate of a silicon oxide film and the in-wafer uniformity of polishing.
[0016] Although the details of the mechanism by which the effects of the present disclosure are manifested are not clear, it is presumed as follows. To improve the polishing rate, it is important that the chemicals are sufficiently adsorbed to cerium oxide and that the surface properties of the cerium oxide are changed. Carboxylic acid structures are responsible for adsorption to cerium oxide, but by substituting alkoxy groups, the adsorption to cerium oxide is improved. On the other hand, to improve the in-plane uniformity of polishing, it is considered important to increase the affinity of the cerium oxide surface with water. If the hydrophobicity is too high, the liquid circulation during polishing deteriorates, so by substituting alkoxy groups, the affinity with water molecules is improved compared to alkyl groups, which is considered to result in improved liquid circulation during polishing and improved in-plane uniformity. However, the present disclosure need not be construed as being limited to these mechanisms. In the present disclosure, the term "liquid flowability" refers to the fluidity of the slurry relative to the polishing pad. In the present disclosure, the term "in-plane uniformity" refers to the processing uniformity within the wafer plane, and is an index of flatness.
[0017] [Polished film] In one or more embodiments, the polishing composition of the present disclosure is a polishing composition (polishing composition for silicon oxide film) used for polishing a silicon oxide film (film to be polished), and can be used in a process requiring polishing of a silicon oxide film. For example, in one or more embodiments, the polishing composition of the present disclosure can be used for polishing a silicon oxide film carried out in a process for forming an element isolation structure of a semiconductor substrate, polishing a silicon oxide film carried out in a process for forming an interlayer insulating film, polishing a silicon oxide film carried out in a process for forming embedded metal wiring, or polishing a silicon oxide film carried out in a process for forming an embedded capacitor. In one or more embodiments, the polishing composition of the present disclosure can be used for manufacturing a three-dimensional semiconductor device such as a three-dimensional NAND flash memory. In particular, in one or more embodiments, the polishing liquid composition of the present disclosure can be suitably used for polishing a substrate (substrate to be polished) having a silicon oxide film convex portion (film to be polished). In one or more embodiments, the silicon oxide film convex portion is a convex portion of a silicon oxide film on a substrate surface, and may be, for example, a convex portion having 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 convex portion can be formed by extra-etching (extra-etching process) before CMP of an interlayer insulating film of a three-dimensional NAND flash memory. In one or more embodiments, the silicon oxide film convex portion is a silicon oxide film convex portion on a substrate surface after extra-etching. In one or more embodiments, the substrate having a silicon oxide film convex portion is a substrate after extra-etching before CMP of an interlayer insulating film of a three-dimensional NAND flash memory. In one or more embodiments, the polishing liquid composition of the present disclosure is for polishing a substrate after extra-etching.
[0018] [Cerium oxide particles (component A)] The polishing liquid composition of the present disclosure contains cerium oxide (hereinafter also referred to as "ceria") particles (hereinafter also simply referred to as "component A") as polishing abrasive grains. As component A, positively charged ceria or negatively charged ceria can be used. The chargeability of component A can be confirmed, for example, by measuring the electric potential (surface potential) on the surface of the abrasive grains obtained by an electroacoustic method (ESA method: Electrokinetic Sonic Amplitude). The surface potential can be measured, for example, using a "Zeta Probe" (manufactured by Kyowa Interface Science Co., Ltd.), 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 rate.
[0019] There may be no particular limitation on the manufacturing method, shape, and surface state of Component A. 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 method described in Examples 1 to 4 of JP-A-2010-505735. Examples of the amorphous ceria include pulverized ceria. One embodiment of the pulverized ceria includes sintered pulverized ceria obtained by sintering and pulverizing a cerium compound such as cerium carbonate or cerium nitrate. Another embodiment of the pulverized ceria includes single crystal pulverized ceria obtained by wet pulverizing ceria particles in the presence of an inorganic acid or an organic acid. An example of the inorganic acid used in the wet pulverization is nitric acid, and an example of the organic acid is an organic acid 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 the wet pulverization, positively charged ceria can be obtained, and when a polycarboxylate such as ammonium polyacrylate is used in the wet pulverization, negatively charged ceria can be obtained. An example of the wet grinding method is 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, for example, Examples 1 to 14 of JP2015-63451A or Examples 1 to 4 of JP2013-119131A. The composite particles can be obtained, for example, by depositing ceria on silica particles.
[0020] Examples of the shape of Component A include a substantially spherical shape, a polyhedral shape, and a raspberry shape.
[0021] From the viewpoint of improving the polishing rate, the average primary particle diameter of component A is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, even more preferably 25 nm or more, even more preferably 30 nm or more, even more preferably 35 nm or more, and even more preferably 40 nm or more, and from the viewpoint of suppressing the occurrence of polishing scratches, it is preferably 300 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, even more preferably 100 nm or less, even more preferably 75 nm or less, and even more preferably 60 nm or less. In the present disclosure, the average primary particle diameter of component A is determined by the BET specific surface area S (m 2 The BET specific surface area can be measured by the method described in the Examples.
[0022] The content of component A in the polishing liquid composition of the present disclosure is preferably 0.1 mass% or more, more preferably 0.15 mass% or more, and even more preferably 0.2 mass% or more from the viewpoint of improving the polishing rate and improving the in-plane uniformity of polishing at the same time, and from the viewpoint of suppressing the occurrence of polishing scratches, it is preferably 10 mass% or less, more preferably 5 mass% or less, more preferably 1 mass% or less, even more preferably 0.75 mass% or less, and even more preferably 0.5 mass% or less. More specifically, the content of component A in the polishing liquid composition of the present disclosure is preferably 0.1 mass% or more and 10 mass% or less, more preferably 0.15 mass% or more and 5 mass% or less, more preferably 0.2 mass% or more and 1 mass% or less, even more preferably 0.2 mass% or more and 0.75 mass% or less, and even more preferably 0.2 mass% or more and 0.5 mass% or less. When component A is a combination of two or more kinds, the content of component A refers to the total content thereof.
[0023] [Alkoxyacetic acid represented by formula (I) or a salt thereof (Component B)] The polishing composition of the present disclosure contains an alkoxyacetic acid represented by the following formula (I) or a salt thereof (hereinafter, also simply referred to as "component B"). Component B is a compound that does not have a hydroxyl group. However, the hydroxyl group (-OH) does not include OH of a carboxy group (-COOH). Component B may be one type or a combination of two or more types. [ka]
[0024] In the formula (I), R represents an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an organic cation, or ammonium (NH4 + In one or more embodiments, the organic cation may be an organic ammonium, such as an alkyl ammonium such as tetramethylammonium, tetraethylammonium, or tetrabutylammonium. In the formula (I), from the viewpoint of achieving both an improvement in the polishing rate and an improvement in the in-plane uniformity of polishing, R is preferably an alkyl group having 1 to 4 carbon atoms, and from the viewpoint of water solubility, R is more preferably an alkyl group having 1 to 2 carbon atoms (methyl group or ethyl group). From the same viewpoint, M is preferably at least one selected from a hydrogen atom, an alkali metal, and an alkaline earth metal, and more preferably a hydrogen atom.
[0025] Examples of component B include at least one selected from methoxyacetic acid or a salt thereof, and ethoxyacetic acid or a salt thereof. Among these, ethoxyacetic acid or a salt thereof is preferred from the viewpoint of simultaneously improving the polishing rate of the silicon oxide film and improving the in-plane uniformity of the polishing.
[0026] The content of component B in the polishing composition of the present disclosure is preferably 0.1 mM or more, more preferably 0.2 mM or more, and even more preferably 0.3 mM or more from the viewpoint of improving the polishing rate and the in-plane uniformity of polishing, and is preferably 10 mM or less, more preferably 5 mM or less, and even more preferably 3 mM or less from the viewpoint of formulation stability. More specifically, the content of component B in the polishing composition of the present disclosure is preferably 0.1 mM or more and 10 mM or less, more preferably 0.2 mM or more and 5 mM or less, and even more preferably 0.3 mM or more and 3 mM or less. When component B is a combination of two or more kinds, the content of component B refers to the total content thereof.
[0027] [Aqueous medium] The aqueous medium contained in the polishing liquid composition of the present disclosure includes water such as distilled water, ion-exchanged water, pure water, and ultrapure water, or a mixed solvent of water and a solvent. The above-mentioned solvent includes a solvent miscible with water (e.g., alcohol such as ethanol). When the aqueous medium is a mixed solvent of water and a solvent, the ratio of water to the entire mixed medium is not particularly limited as long as the effect of the present disclosure is not hindered. From the viewpoint of economic efficiency, for example, 95 mass% or more is preferable, 98 mass% or more is more preferable, and less than 100 mass% is preferable. From the viewpoint of surface cleanliness of the substrate to be polished, the aqueous medium is preferably water, more preferably ion-exchanged water and ultrapure water, and even more preferably ultrapure water. The content of the aqueous medium in the polishing liquid composition of the present disclosure can be the remainder excluding Component A, Component B, and any optional components described below that are blended as necessary.
[0028] [Optional ingredients] The polishing liquid composition of the present disclosure may further contain optional components such as a pH adjuster, a surfactant, a thickener, a dispersant, an antirust agent, an antiseptic, a basic substance, a polishing rate enhancer, a silicon nitride film polishing suppressor, or a polysilicon film polishing suppressor.
[0029] In one or a plurality of embodiments, the polishing liquid composition of the present disclosure is substantially free of colloidal silica whose surface exhibits a positive ζ-potential. For example, the content of the colloidal silica in the polishing liquid composition of the present disclosure is preferably less than 1 mass%, more preferably 0.1 mass% or less, even more preferably 0.01 mass% or less, and even more preferably 0 mass% (i.e., no colloidal silica is contained). In one or more embodiments, the polishing liquid composition of the present disclosure is substantially free of a corrosion inhibitor. For example, the content of the corrosion inhibitor in the polishing liquid composition of the present disclosure is preferably less than 0.01% by mass, more preferably 0% by mass (i.e., no corrosion inhibitor is contained). In one or more embodiments, the polishing liquid composition of the present disclosure is substantially free of a cationic surfactant. For example, the content of the surfactant in the polishing liquid composition of the present disclosure is preferably less than 0.001 g, and more preferably 0 g (i.e., no surfactant is contained) per 1 L of the polishing liquid.
[0030] [Polishing liquid composition] The polishing liquid composition of the present disclosure can be produced by a production method including a step of blending component A, component B, an aqueous medium, and an optional component as required by a known method. For example, the polishing liquid composition of the present disclosure can be produced by blending a dispersion (slurry) containing component A and an aqueous medium, a solution containing component B and an aqueous medium, and an optional component as required. In the present disclosure, "blending" includes mixing component A, component B, an aqueous medium, and an optional component as required simultaneously or in sequence. The order of mixing is not particularly limited. The blending can be performed using a mixer such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. The blending amount of each component in the production method of the polishing liquid composition of the present disclosure can be the same as the content of each component in the polishing liquid composition of the present disclosure described above.
[0031] The embodiment of the polishing liquid composition of the present disclosure may be a so-called one-liquid type in which all components are supplied to the market in a pre-mixed state, or a so-called two-liquid type in which the components are mixed at the time of use. For example, in one or more embodiments, a two-liquid type polishing liquid composition may be composed of a first liquid containing component A and a second liquid containing component B, and the first liquid and the second liquid are mixed at the time of use. The first liquid and the second liquid may be mixed before being supplied to the surface of the object to be polished, or they may be supplied separately and mixed on the surface of the substrate to be polished. The first liquid and the second liquid may each contain the above-mentioned optional components as necessary.
[0032] The pH of the polishing liquid composition of the present disclosure is preferably more than 3.5, more preferably 4 or more, from the viewpoint of simultaneously improving the polishing rate of the silicon oxide film and improving the in-plane uniformity of polishing, and from the same viewpoint, is preferably 7.5 or less, more preferably 6.5 or less, even more preferably 5.5 or less, and even more preferably 5 or less. More specifically, the pH of the polishing liquid composition of the present disclosure is preferably more than 3.5 and 7.5 or less, more preferably 4 or more and 6.5 or less, even more preferably 4 or more and 5.5 or less, and even more preferably 4 or more and 5 or less. In the present disclosure, the pH of the polishing liquid composition is a value at 25°C, and is a value measured using a pH meter. Specifically, the pH of the polishing liquid composition of the present disclosure can be measured by the method described in the Examples.
[0033] In the present disclosure, "the content of each component in the polishing liquid composition" refers to the content of each component at the time of polishing, that is, at the time when the polishing liquid composition starts to be used for polishing. In one or more embodiments, the content of each component in the polishing liquid composition of the present disclosure can be considered as the blending amount of each component in the polishing liquid composition of the present disclosure. The polishing composition of the present disclosure may be stored and supplied in a concentrated state to the extent that its stability is not impaired. In this case, it is preferable in that the manufacturing and transportation costs can be reduced. If necessary, this concentrated liquid can be appropriately diluted with the above-mentioned aqueous medium and used in the polishing process. The dilution ratio is preferably 5 to 100 times.
[0034] [Polishing liquid kit] In one aspect, the present disclosure relates to a kit for preparing the polishing liquid composition of the present disclosure (hereinafter also referred to as the "polishing liquid kit of the present disclosure"). The polishing liquid kit of the present disclosure may be, for example, a polishing liquid kit (two-liquid type polishing liquid composition) that contains an abrasive dispersion liquid (first liquid) containing component A and an aqueous medium and an additive aqueous solution (second liquid) containing component B in a mutually unmixed state, which are mixed at the time of use and diluted with an aqueous medium as necessary. The aqueous medium contained in the abrasive dispersion liquid (first liquid) may be the entire amount of the aqueous medium used in the preparation of the polishing liquid composition, or may be a part of the aqueous medium. The additive aqueous solution (second liquid) may contain a part of the aqueous medium used in the preparation of the polishing liquid composition. The abrasive dispersion liquid (first liquid) and the additive aqueous solution (second liquid) may each contain the above-mentioned optional components as necessary. The abrasive dispersion liquid (first liquid) and the additive aqueous solution (second liquid) may be mixed before being supplied to the surface of the object to be polished, or they may be supplied separately and mixed on the surface of the substrate to be polished. According to the polishing liquid kit of the present disclosure, a polishing liquid composition that can simultaneously improve the polishing speed of a silicon oxide film and improve the in-plane uniformity of polishing can be obtained.
[0035] [Polishing method] In one aspect, the present disclosure relates to a polishing method (hereinafter also referred to as the polishing method of the present disclosure), 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 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 the present disclosure described above. For example, in one or more embodiments, the film to be polished in the polishing method of the present disclosure is a silicon oxide film convex portion on the substrate surface after extra etching. In one or more embodiments, the polishing method of the present disclosure includes a step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure. In one or more embodiments, examples of the substrate to be polished include a substrate after extra etching and a substrate having a silicon oxide film convex portion. By using the polishing method of the present disclosure, it is possible to improve both the polishing speed of the silicon oxide film and the in-plane uniformity of polishing, and therefore the productivity of semiconductor substrates with improved quality can be improved. The polishing method and conditions in the polishing method of the present disclosure can be the same as those in the manufacturing method of semiconductor substrates of the present disclosure described below.
[0036] [Method of manufacturing semiconductor substrate] In one aspect, the present disclosure relates to a method for producing a semiconductor substrate (hereinafter also referred to as the "method for producing a semiconductor substrate of the present disclosure"), which includes a step of polishing a film to be polished (polishing step) using the polishing liquid composition of the present disclosure. Examples of the film to be polished include the film to be polished in the polishing liquid composition of the present disclosure. For example, in one or more embodiments, examples of the film to be polished in the method for producing a semiconductor substrate of the present disclosure include a silicon oxide film convex portion on the substrate surface after extra etching. In one or more embodiments, the method for producing a semiconductor substrate of the present disclosure includes a step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure. In one or more embodiments, examples of the substrate to be polished include a substrate after extra etching, a substrate having a silicon oxide film convex portion, and the like. According to the method for producing a semiconductor substrate of the present disclosure, it is possible to achieve both an improvement in the polishing speed of the silicon oxide film and an improvement in the in-plane uniformity of polishing, and therefore a semiconductor substrate with improved quality can be efficiently produced.
[0037] As a specific example of the method for manufacturing a semiconductor substrate according to the present 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. Then, a channel is formed by polysilicon, the laminated film is trimmed, a charge trap layer is formed, and a tungsten (W) gate is formed to form an array. Then, a silicon dioxide layer is laminated on the array by a CVD method (chemical vapor deposition method) or the like. The silicon oxide film thus formed has a large step difference between the array portion and the peripheral portion. Next, the silicon oxide film of the array portion is polished by CMP until it is at the same height as the peripheral portion. As shown in FIG. 1, a method has been proposed in which an extra-etching process is performed before CMP to make the convex portion finer, improve CMP efficiency, and shorten the polishing time. In one or more embodiments, the polishing liquid composition of the present disclosure can be suitably used for polishing a substrate having a silicon oxide film protrusion after extra etching. In one or more embodiments, the silicon oxide film protrusion refers to a silicon oxide film protrusion on the substrate surface, and examples of the protrusion include a protrusion having a width of 10 μm to 500 μm and a height of 4 μm to 10 μm.
[0038] In polishing by CMP, the surface of the substrate to be polished is brought into contact with a polishing pad, and the substrate to be polished and the polishing pad are moved relative to each other while the polishing liquid composition of the present disclosure is supplied to the contact site, thereby making it possible to flatten the uneven portions of the surface of the substrate to be polished.
[0039] In the polishing step, 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 in the polishing apparatus equipped with the polishing pad is, for example, 20 to 500 gf / cm. 2 The supply rate of the polishing composition can be set to, for example, 10 to 500 mL / min. When the polishing composition is a two-liquid type polishing composition, the polishing rate of the film to be polished can be adjusted by adjusting the supply rates (or supply amounts) of the first liquid and the second liquid.
[0040] In the polishing step, the polishing rate 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
[0041] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to these examples in any way.
[0042] 1. Preparation of polishing composition [Preparation of Polishing Compositions of Examples 1 to 2 and Comparative Examples 1 to 3] Cerium oxide particles (component A), a compound shown in Table 1 (component B or non-component B), and water were mixed to obtain polishing liquid compositions of Examples 1 and 2 and Comparative Examples 1 to 3. The blending amount (content) of each component in the polishing liquid composition (mass % or mM, active content) is as shown in Table 2, and the content of water is the remainder excluding component A and component B or non-component B. The pH was adjusted using ammonia or nitric acid.
[0043] The following were used for component A, component B, and non-component B. (Component A) Calcined and ground ceria [average primary particle size: 45 nm, BET specific surface area: 17 m 2 / g, surface potential: 70mV] (Component B) B1: Ethoxyacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (I), R=C2H5, M=H.] B2: Methoxyacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) [In formula (I), R=CH3, M=H.] (Non-ingredient B) B3: Acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) B4: Glycolic acid (Tokyo Chemical Industry Co., Ltd.) B5: Butyric acid (Tokyo Chemical Industry Co., Ltd.)
[0044] [Table 1]
[0045] 2.Measuring methods for various parameters [Average primary particle size of cerium oxide particles (component A)] The average primary particle diameter (nm) of cerium oxide particles is calculated by the BET (nitrogen adsorption) method. 2 / g) and is calculated by the following formula: In the formula below, the specific surface area S was determined by drying 10 g of a slurry of cerium oxide particles under reduced pressure at 110°C to remove moisture, crushing the resultant powder in an agate mortar, and measuring the powder using a flow type automatic specific surface area measuring device, FlowSorb 2300 (manufactured by Shimadzu Corporation). Average primary particle diameter (nm)=820 / S
[0046] [Surface potential of cerium oxide (component A)] The surface potential (mV) of the cerium oxide particles was measured using a surface potential measuring device (Kyowa Interface Science Co., Ltd., Zeta Probe). The cerium oxide concentration was adjusted to 0.3% using ultrapure water, and the solution was placed in the surface potential measuring device, where the surface potential was measured under conditions of a particle density of 7.13 g / ml and a particle dielectric constant of 7. The measurement was performed three times, and the average value was used as the measurement result.
[0047] [pH of polishing composition] The pH value of the polishing composition at 25° C. was measured using a pH meter (HM-30G, Toa Denpa Kogyo Co., Ltd.) one minute after the electrode was immersed in the polishing composition. The results are shown in Table 2.
[0048] 3. Evaluation of Polishing Compositions (Examples 1-2 and Comparative Examples 1-3) [Evaluation sample] A silicon wafer was prepared as an evaluation sample (substrate to be polished) by forming a silicon oxide film (blanket film) having a thickness of 2000 nm on one side thereof by the TEOS-plasma CVD method.
[0049] [Polishing conditions] Polishing equipment: Single-sided polishing machine [Ebara Corporation, FREX-200] Polishing pad: Hard urethane pad "IC-1000 / Suba400" [manufactured by Nitta Haas] Plate rotation speed: 100 rpm Head rotation speed: 107 rpm Polishing load: 280hPa Polishing liquid supply amount: 200mL / min Polishing time: 1 minute
[0050] [Polishing speed] The evaluation samples were polished under the above-mentioned polishing conditions using each of the polishing compositions of Examples 1 and 2 and Comparative Examples 1 and 3. For Comparative Example 2, the test could not be carried out due to aggregation of the ceria particles. The thickness of the silicon oxide film before and after polishing was measured using an ASET-F5X (KLA). The film thickness was measured at 4 mm intervals from the edge to the center of the wafer, excluding the 3 mm area at the edge, for a total of 47 measurement points. The polishing speed of the silicon oxide film (film to be polished) was calculated as the average value of the above 47 points using the following formula, and the results are shown in Table 2. Polishing speed = [silicon oxide film thickness before polishing (nm) - silicon oxide film thickness after polishing (nm)] / polishing time (min)
[0051] [In-plane uniformity] WIWNU, which is an index of in-plane uniformity, was calculated using the following formula, and the results are shown in Table 2. WIWNU(%) = [Standard deviation of silicon oxide film polishing speed × 100] / silicon oxide film polishing speed (nm / min) This shows that the larger the polishing rate deviation among the 47 film thickness measurement points within the wafer surface and the smaller the average polishing rate, the larger the WIWNU value. In other words, the smaller the polishing rate deviation within the wafer surface and the larger the average polishing rate, the smaller the WIWNU value, indicating excellent within-wafer uniformity.
[0052] [Table 2]
[0053] As shown in Table 2, it was found that the polishing compositions of Examples 1 and 2 were able to improve both the removal rate of the silicon oxide film and the in-plane uniformity, compared with Comparative Examples 1 and 3. The polishing composition of Comparative Example 2 could not be evaluated because it produced sediment. [Industrial Applicability]
[0054] The polishing composition according to the present disclosure is useful in a method for manufacturing semiconductor devices for high density or high integration.
Claims
1. A polishing composition for silicon oxide films, comprising cerium oxide particles (component A), an alkoxyacetic acid represented by the following formula (I) or a salt thereof (component B), and an aqueous medium: 【Chemical 1】 In the formula (I), R represents an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an organic cation, or ammonium (NH 4 + ) is shown.
2. The polishing composition according to claim 1 , wherein the content of Component A is 0.1% by mass or more and 10% by mass or less.
3. 3. The polishing composition according to claim 1, wherein the content of Component B is 0.1 mM or more and 10 mM or less.
4. 3. The polishing composition according to claim 1, wherein Component B is at least one selected from the group consisting of methoxyacetic acid or a salt thereof, and ethoxyacetic acid or a salt thereof.
5. 5. The polishing composition according to claim 4, wherein Component B is ethoxyacetic acid or a salt thereof.
6. The polishing composition according to claim 1 or 2, wherein the pH of the polishing composition is greater than 3.5 and not greater than 7.
5.
7. A method for producing a semiconductor substrate, comprising a step of polishing a film to be polished with the polishing composition according to claim 1 or 2.
8. 3. A polishing method comprising the step of polishing a film to be polished with the polishing composition according to claim 1, wherein the film to be polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate.