Negatively charged silica particles, methods for making such particles, compositions containing such particles, and methods for chemical mechanical polishing using such particles - Patents.com

Abstract

The present application relates to negatively charged silica particles, to methods of making such particles, and to compositions including such particles, as well as to methods for chemical mechanical polishing.

Description

[Technical field]

[0001] Technical Field The present application relates to negatively charged silica particles, to methods of making such particles, and to compositions including such particles, as well as to methods for chemical mechanical polishing.

[0002] background Modern semiconductor devices, memory devices, integrated circuits, etc., contain alternating conductive, semiconductive, and dielectric (or insulating) layers, with the dielectric layers insulating the conductive layers from one another. Connections between the conductive layers may be established, for example, by metal vias. In the manufacture of such devices, conductive, semiconductive, and / or dielectric materials are successively deposited on an underlying substrate on a semiconductor wafer, and portions are removed again from the underlying substrate on the semiconductor wafer.

[0003] Such devices are becoming smaller and smaller, and the accuracy and thickness of the deposition of the various layers becomes more important to ensure that the devices so manufactured function as expected. It is therefore important to have a planar surface on which the subsequent layers are deposited. When the required planarity cannot be achieved by deposition, the wafer (respectively the device to be manufactured) needs to be planarized by removing parts or in some cases even all of such layers.

[0004] Chemical mechanical polishing (CMP) is a widely used method for planarizing or removing part or all of a layer during the manufacturing of semiconductor devices and the like. In a CMP process, an abrasive and / or corrosive chemical slurry, such as a slurry of silica particles, is used in conjunction with a polishing pad. The pad and substrate or surface, e.g., a wafer, are pressed together and rotated, typically non-concentrically, i.e., with different axes of rotation, thereby scraping and removing material from the surface or substrate.

[0005] Chemical mechanical polishing can be used to polish a wide range of materials used in semiconductors, etc., such as metals and metal alloys (such as aluminum, copper, or tungsten), metal oxides, silicon dioxide, or even polymeric materials. For each material, the polishing slurry must be specifically formulated to optimize its performance.

[0006] As already indicated by the term "chemical mechanical polishing", polishing is essentially carried out by a combination of mechanical polishing and chemical corrosion.As a result, the silica particles used as abrasives in this process must not only be mechanically robust, but also exhibit certain properties and meet certain requirements so as to be fully suitable as a component of high-performance CMP slurries.For example, the composition of silica particles must be modified depending on whether the particles need to be anionic or cationic.

[0007] It is known to produce silica particles with negatively charged surfaces by modifying the silica surface with aluminate ions (see RK Iler, "The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica", Wiley, 1979, pp. 407-40). However, it has been found that such surface-modified silica particles exhibit a high tendency to lose aluminum from the surface, making it difficult to target a specific concentration of aluminum, and therefore a specific charge, which is essential for efficient and reproducible performance in chemical mechanical polishing.

[0008] From US 4,217,240, homogeneous amorphous aluminosilicate particles and core-shell particles with an aluminosilicate coating are known, as well as the production of such particles in dry form. The resulting particles have a high ratio of Si / Al of 1:1 to 19:1, which makes them suitable for their intended use as porous catalyst powders, but unsuitable for chemical mechanical polishing.

[0009] M.-S. Tsai and W.-C. Wu in Materials Letters 58 (2004) 1881-1884 disclose negatively charged colloidal silica in the acidic range formed by adding Al ions in the form of Al(NO3)3 together with active silicic acid to silica particle seeds during the surface growth process. However, the observed precipitation of Al(OH)3 can make it difficult to target a specific aluminum content and, consequently, a specific negative charge in the resulting particles.

[0010] Furthermore, there is no disclosure in any of these documents that such negatively charged aluminum-containing silica particles could be useful in chemical mechanical polishing.

[0011] Thus, there remains a need in the industry to provide silica particles that enable good removal rate selectivity between conductive and / or semiconductive materials on the one hand and dielectric materials on the other hand for improved efficiency of manufacturing processes.

[0012] It is therefore an object of the present application to provide silica particles and compositions comprising such silica particles that allow good selectivity between one or more conductive layers, which may comprise any one or more of metals, metal alloys, polysilicon, and any other suitable material, and one or more dielectric layers, preferably in a manner such that the removal rate of the dielectric material is significantly lower than that of metals and metal alloys, specifically tungsten. Summary of the Invention

[0013] overview The present inventors have surprisingly found that one or more of the above objectives may be achieved by the compositions and methods as described herein.

[0014] Accordingly, the present application provides a composition comprising water and core-shell silica particles, wherein the composition is acidic, and the core-shell silica particles comprise a core and a shell, the shell comprising aluminate moieties within the outer surface of the silica particles.

[0015] The present application also relates to a method for producing such a composition, the method comprising the steps of: (a) providing silica particles; (b) providing an aqueous solution of silicic acid and providing an aqueous solution of sodium aluminate, and reacting the silicic acid and sodium aluminate in the presence of the silica particles provided in the previous step under alkaline conditions and at a temperature of at least 40° C. to form a shell on the silica particles, thereby producing core-shell silica particles; and (c) passing the core-shell silica particles produced in the previous step through a column of a cation exchange resin; thereby obtaining said composition, The method includes:

[0016] Additionally, the present application provides a method for chemical mechanical polishing, comprising the steps of: (A) providing a substrate to be polished; (B) providing the composition; (C) providing a chemical mechanical polishing pad having an abrasive surface; (D) contacting the polishing surface of the chemical mechanical polishing pad with the substrate; and (E) polishing the substrate such that at least a portion of the substrate is removed; The method includes:

[0017] Detailed Description As used herein, "Me" refers to a methyl group (CH3) and "Et" refers to an ethyl group (CH2-CH3).

[0018] As used herein, the term "water glass" is used generally to denote alkali salts, preferably sodium and potassium salts, of silicic acid, Si(OH)4. The respective sodium and potassium salts can be, for example, represented by the formula M 2x S y O 2y+x or (M2O) x· (SiO2) y , M=Na or K, and, for example, x=1 and y is an integer from 2 to 4.

[0019] As used herein, the term "waterglass-based" is used to indicate that the present silica particles are preferably made from such alkali salts of silicic acid as starting materials.

[0020] As used herein, the term "TMOS / TEOS-based" is used generally to refer to silica particles produced using Si(OMe)4 ("TMOS") and / or Si(OEt)4 ("TEOS") as starting materials.

[0021] As used herein, the term "silicate" is used to denote salts and esters of orthosilicic acid (Si(OH)4), which may also be referred to as "silicic acid" throughout this application, as well as condensation products thereof. It should also be noted that a gel or solution of silicic acid is generally understood to also include condensates of silicic acid.

[0022] As used herein, the term "aluminate" is used primarily to denote tetrahydroxyaluminate, which is [Al(OH)4] - When incorporated into a silica particle, the term "aluminate" is used to indicate a chemical group, e.g., as used in an "aluminate moiety" or an "aluminate-containing shell," which is [Al(-O-)4]- Without wishing to be bound by theory, it is believed that the three outer electrons of aluminum are removed, thereby forming an Al 2 O 3 bond with -O- acting as a bridge to adjacent aluminum or silicon atoms. 3+ ions, or alternatively, preferably protons or alkali metal ions (preferably Na + or K + ) is considered to be "filled" with

[0023] As used herein, the term "colloidal" is used to denote particles dispersed in a medium having a dimension between 1 nm and 1 μm in at least one direction (see also Compendium of Chemical Terminology, Gold Book, International Union of Pure and Applied Chemistry, Version 2.3.3, 2014-02-24, p. 295).

[0024] As used herein, the term "point of use" refers to a chemical mechanical polishing (CMP) process. For example, the phrase "point of use composition" is used to refer to a composition as it is used in a chemical mechanical polishing process.

[0025] Generally, silica particles, for example, colloidal silica based on water glass, are well known to those skilled in the art and can be obtained in a wet process from the starting materials described above, for example, as disclosed in RK Iler "The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica" Wiley, 1979. For producing the silica particles contained in the silica slurry, it is preferred that the silica particles are obtained in a wet process from an alkaline silicate.

[0026] The present invention will be described by the example of colloidal silica particles based on water glass, but the type of actual particles is not specifically limited.Thus, the silica particles used herein can be, for example, any type of colloidal silica particles.The silica particles can be made from any suitable starting material, for example, can be based on water glass or TMOS / TEOS.However, preferably, the silica particles used herein are colloidal silica particles and can be based on water glass.

[0027] Generally speaking, the present application relates to a composition comprising water and core-shell silica particles, wherein the composition is acidic.

[0028] The composition is acidic.Preferably, it has a pH of at least 1.5.Preferably, it has a pH of at most 5.5, more preferably at most 5.0, even more preferably at most 4.5, even more preferably at most 4.0, and most preferably at most 3.5.

[0029] The composition preferably has a zeta potential of at most 0 mV. Preferably, the composition has a zeta potential of at least -30 mV. Thus, the zeta potential of the particles is preferably in the range of 0 mV to -30 mV. The zeta potential can be determined as described in the examples.

[0030] The core-shell silica particles may be included in the composition in at least 0.1 wt% and at most 50 wt% based on the total weight of the composition.The specific content of the core-shell silica particles in the composition may depend, for example, on whether the composition is supplied as a concentrate, for example for transportation, or when it is actually used at the point of use.

[0031] When supplied as a concentrate and then diluted with water, preferably deionized water, prior to its use in a chemical mechanical polishing process, the composition may comprise up to 50 wt.%, for example up to 25 wt.%, or up to 30 wt.%, or up to 35 wt.%, or up to 40 wt.%, of the core-shell silica particles, based on the total weight of the composition.

[0032] Alternatively, when used at point of use, i.e. in chemical mechanical polishing process, the composition preferably comprises the core-shell silica particles in at least 0.1wt% (for example, at least 0.2wt% or 0.3wt% or 0.4wt%), more preferably at least 0.5wt%, even more preferably at least 1.0wt%, even more preferably at least 1.5wt%, and most preferably at least 2.0wt% of the core-shell silica particles in wt% based on the total weight of the composition.In this case, the composition preferably comprises the core-shell silica particles in at most 10wt%, more preferably at most 5.0wt%, even more preferably at most 4.0wt%, even more preferably at most 3.5wt%, and most preferably at most 3.0wt%, based on the total weight of the composition.

[0033] The core-shell silica particles comprise a core and a shell, but may comprise more than one shell.

[0034] Such a shell, and preferably the outermost shell if more than one shell is present, comprises an aluminate moiety within the outer surface of the core-shell silica particle. Throughout this application, the term "shell comprising an aluminate" will be used to denote a shell comprising an aluminate moiety.

[0035] Preferably, the aluminate-containing shell has a thickness of at least 0.1 nm, more preferably at least 0.15 nm, and most preferably at least 0.2 nm. Preferably, the aluminate-containing shell has a thickness of at most 2.0 nm, more preferably at most 1.8 nm, even more preferably at most 1.6 nm or 1.4 nm, even more preferably at most 1.2 nm, and most preferably at most 1.0 nm.

[0036] The amount of aluminum contained in the aluminate-containing shell can be adjusted to achieve the negative charge required for the target application. Such variation of aluminum content is well within the skill of a specialist. However, it has been found that the present core-shell silica particle is most suitable for chemical mechanical polishing when the amount of aluminum contained in the aluminate-containing shell is at least 500 ppm or 1,000 ppm, more preferably at least 2,000 ppm, even more preferably at least 3,000 ppm, even more preferably at least 4,000 ppm, and most preferably at least 5,000 ppm, based on the total weight of the aluminate-containing shell of the present core-shell silica particle. The amount of aluminum contained in the aluminate-containing shell is preferably at most 25,000 ppm, more preferably at most 20,000 ppm, even more preferably at most 15,000 ppm, and most preferably at most 10,000 ppm, based on the total weight of the aluminate-containing shell of the present core-shell silica particle.

[0037] The shape and size of the silica particles used herein are not particularly limited, provided that such silica particles are suitable for CMP applications. Such silica particles may be, for example, spherical, oval, curvilinear, curved, elongated, branched, or conical.

[0038] For spherical silica particles, the average diameter is preferably at least 5nm, more preferably at least 10nm, and most preferably at least 15nm.For spherical particles, the average diameter is preferably at most 200nm, more preferably at most 150nm or 100nm, even more preferably at most 90nm or 80nm or 70nm or 60nm, even more preferably at most 50nm or 45nm or 40nm or 35nm or 30nm, and most preferably at most 25nm.For example, specifically preferred silica particles have an average diameter of at least 15nm and at most 25nm.

[0039] For elongated, curved, bent, branched and oval silica particles, their average diameter is preferably as described above for spherical colloidal silica particles.Preferably, such elongated or oval colloidal silica particles have an aspect ratio, i.e., the ratio of length to average diameter, of at least 1.1, more preferably at least 1.2 or 1.3 or 1.4 or 1.5, even more preferably at least 1.6 or 1.7 or 1.8 or 1.9, and most preferably at least 2.0.Said aspect ratio is preferably at most 10, more preferably at most 9 or 8 or 7 or 6, and most preferably at most 5.

[0040] Generally, the core-shell silica particles can be produced by standard methods. In a first step, silica particles are provided, followed by forming the core of the core-shell silica particles. Thus, the method for producing a composition comprising water and core-shell silica particles, in particular for producing the core-shell silica particles, comprises the following steps: (a) providing silica particles; Includes.

[0041] In step (a), these silica particles can be provided either by producing them in situ through polycondensation of silicic acid, or alternatively by providing so-called "seed particles". Such seed particles are silica particles, preferably colloidal silica particles, such as water glass-based colloidal silica particles, that are smaller in size (e.g. smaller diameter) than the target size of the core-shell silica particles. These seed particles can then be directly used as seed particles in the following step (b), or alternatively, a shell of silica is deposited on such seed particles by polycondensing silicic acid on the surface of the seed particles until the desired particle size is reached, and then the resulting particles can be used as seed particles for the following step (b).

[0042] It should be noted that the silica particles provided in step (a), whether produced in situ or alternatively provided as seed particles, are preferably silica particles obtained through polycondensation of silicic acid alone, which may also be referred to as silica particles obtained through "homopolycondensation of silicic acid".

[0043] In the subsequent step (b), an aluminate-containing shell is formed by reacting an aqueous solution of silicic acid with an aqueous solution of an aluminate, preferably sodium aluminate. Thus, the method for producing a composition comprising water and core-shell silica particles, in particular for producing the core-shell silica particles, comprises the following steps: (b) providing an aqueous solution of silicic acid and an aqueous solution of an aluminate, preferably an aqueous solution of sodium aluminate, and reacting in the presence of the silica particles provided in step (a) above to form a shell, in particular an aluminate-containing shell, on the silica particles provided in step (a) above, thereby producing core-shell silica particles as defined herein; Includes.

[0044] The reaction (or polycondensation) of silicic acid with aluminate in step (b) is carried out under alkaline conditions, preferably at a pH of at least 8, more preferably at a pH of at least 9, and most preferably at a pH of at least 10.

[0045] It should be noted that step (b) is in fact a co-condensation of silicic acid with an aluminate (i.e., tetrahydroxyaluminate), thereby producing what may be called a co-condensate. Without wishing to be bound by theory, it is believed that the distribution of aluminum and silicon in such a co-condensate is random. In contrast, surface modification of silica particles with an aluminate will result in a layer of aluminate moieties on top.

[0046] In cases where the pH needs to be adjusted to be more basic, such adjustment may be made by adding a base. Such base may be any suitable base. However, such base is preferably selected from the group consisting of potassium hydroxide, sodium hydroxide, lithium hydroxide, cesium hydroxide, rubidium hydroxide, ammonia, organic amines, and any blends thereof. Of these, potassium hydroxide and ammonia are particularly preferred.

[0047] Suitable organic amines may be selected from the group consisting of alkylamines, alkanolamines, and any blends thereof, with alkanolamines being preferred.

[0048] Examples of suitable alkylamines are those of the following formula (I): H 3-a NR 1 a (I) where a, in each occurrence, is independently an integer selected from the group consisting of 1, 2, and 3; and R 1 is an alkyl group having 1, 2, or 3 carbon atoms; Preferred alkylamines may be selected from the group consisting of methylamine (H2NMe), dimethylamine (HNMe2), trimethylamine (Nme3), ethylamine (H2Net), diethylamine (HNEt2), triethylamine (Net3), and any blends thereof.

[0049] Examples of suitable alkanolamines are those of the following formula (II): H2N-R 2 -OH (II) Here, R 2 is, at each occurrence, independently an alkanediyl having at least 1, and at most 5, carbon atoms; Therefore, R 2 may be independently selected at each occurrence from the group consisting of methylene (-CH-), ethanediyl (-CH-CH-), propanediyl (-(CH-)), butanediyl (-(CH-)), and pentanediyl (-(CH-)).

[0050] Preferred alkanolamines may be selected from the group consisting of 2-aminoethanol, 3-aminopropanol, and 4-aminobutanol, with 2-aminoethanol being most preferred.

[0051] The reaction (or polycondensation) of silicic acid with aluminate in step (b) is carried out at a temperature of at least 40°C, preferably at least 50 or 60°C.

[0052] The molar ratio of aluminum to silicon in step (b) can be appropriately adjusted to reach the target aluminum content in the aluminate-containing shell of the core-shell silica particle as described herein.Preferably, the molar ratio of aluminum to silicon in step (b) is selected so that the aluminate-containing shell contains aluminum in the amount defined above.Such a selection is well within the scope of the view of the skilled artisan and--in view of the further information provided by the example--does not require extensive experimentation.As a non-limiting example, the molar ratio of aluminum to silicon (Al:Si) in step (b) can be, for example, at least 0.001 and at most 0.10, preferably at most 0.09.

[0053] The core-shell silica particles thus obtained from step (b) are then passed through a column of a cation exchange resin. The present method for producing a composition comprising water and core-shell silica particles, in particular for producing the present core-shell silica particles, comprises the following steps: (c) passing the core-shell silica particles produced in the previous step through a column of a cation exchange resin; thereby obtaining a composition as defined above, Includes.

[0054] The core-shell silica particles may optionally include an alkoxyorganosilane on the surface. Preferably, such alkoxyorganosilane is hydrophilic.

[0055] The alkoxyorganosilanes used herein are preferably poly(alkoxy)organosilanes. More preferably, the alkoxyorganosilanes have the following formula (III): [ka] During the ceremony R 11 and R 12 are each independently selected from the group consisting of methyl, ethyl and propyl; b is an integer of at least 1 and at most 5; and c is an integer of at least 1 and at most 30, preferably at most 25, and even more preferably at most 20; It is expressed as:

[0056] Preferred examples of alkoxyorganosilanes represented by formula (III) are 11 and R 12 are all Me or Et, b is 3, and c is at least 6 and at most 12. For example, c can be at least 6 and at most 9, or at least 9 and at most 12, or at least 8 and at most 12.

[0057] Most preferably, the alkoxyorganosilane used herein is one represented by formula (III), where R 11 and R 12 are all methyl, b is 3, and c is 11.

[0058] Such alkoxyorganosilanes may be obtained, for example, from Momentive Performance Materials, Albany, NY, USA.

[0059] Preferably, the alkoxyorganosilane, as defined herein, is reacted with the silica particles at a weight ratio of alkoxyorganosilane to silica particles of at least 0.001, more preferably at least 0.005, even more preferably at least 0.010, even more preferably at least 0.015, and most preferably at least 0.020.

[0060] Preferably, the alkoxyorganosilane as defined herein is reacted with the silica particles at a weight ratio of alkoxyorganosilane to silica particles of at most 0.50, more preferably at most 0.40 or 0.30, even more preferably at most 0.20, even more preferably at most 0.15 or 0.10, and most preferably at most 0.050.

[0061] The alkoxyorganosilane modified silica particles can be prepared by the following steps: (1) providing an aqueous dispersion of core-shell silica particles as defined above; and (2) providing an alkoxyorganosilane as defined above; It can be produced by a process including:

[0062] For this reason, the aqueous dispersion of silica particles needs to be acidic, and the present method for producing alkoxyorganosilane-modified silica particles also includes the following steps: (3) acidifying the aqueous dispersion of silica particles if it is not already acidic, and preferably adjusting the pH of the aqueous dispersion to have a pH of at least 1.0, more preferably at least 2.0, and a maximum pH of 5.0, more preferably a maximum pH of 4.0; Includes.

[0063] In the following, the acidic aqueous dispersion of silica particles and the alkoxyorganosilane as defined herein are brought into contact with each other, thereby obtaining alkoxyorganosilane-modified silica particles. This can be done simply by mixing the acidic aqueous dispersion of silica particles with the alkoxyorganosilane and stirring, optionally for a given time, optionally at an elevated temperature.

[0064] Thus, the method comprises the following steps: (4) then contacting the silica particles and the alkoxyorganosilane with each other, thereby obtaining alkoxyorganosilane-modified silica particles; Includes.

[0065] However, it can also be preferred that the core-shell silica particles do not comprise an alkoxyorganosilane as defined herein.

[0066] Optionally, the composition further comprises any one or more of the group consisting of a biocide, a pH adjuster, a pH buffer, an oxidizing agent, a chelating agent, a corrosion inhibitor, and a surfactant.

[0067] Such oxidizing agent can be any suitable oxidizing agent for one or more metals or metal alloys of the substrate to be polished using the composition.For example, the oxidizing agent can be selected from the group consisting of bromate, bromite, chlorate, chlorite, hydrogen peroxide, hypochlorite, iodate, peroxymonosulfate, peroxymonosulfite, peroxymonophosphate, peroxyprimaryphosphate, peroxymonopyrophosphate, organo-o-halooxy compounds, iodate, permanganate, peroxyacetic acid, iron nitrate, and any blend thereof.Such oxidizing agent can be added in a suitable amount, for example, at least 0.1 wt% and up to 6.0 wt% in wt% based on the total weight of the composition at the point of use.

[0068] Such an anticorrosive agent may be, for example, a film-forming agent, and may be any suitable anticorrosive agent, for example, glycine, which may be added in an amount of at least 0.001 wt% to 3.0 wt% based on the total weight of the composition at the point of use.

[0069] Such chelating agents may be any suitable chelating or complexing agent, alternatively or in combination, for increasing the removal rate of the respective material to be removed, preferably metal or metal alloy, or for scavenging trace metal contaminants that may adversely affect the performance in the polishing process or in the finished device. For example, the chelating agent may be a compound that includes one or more functional groups that include oxygen (e.g., carbonyl, carboxyl, hydroxyl, etc.) or nitrogen (e.g., amine, or nitrate, etc.). Examples of suitable chelating agents include, in a non-limiting manner, acetylacetonates, acetates, arylcarboxylates, glycolates, lactates, gluconates, gallates, oxalates, phthalates, citrates, succinates, tartrates, malates, ethylenediaminetetraacetic acid and their salts, ethylene glycol, pyrogallol, phosphonates, ammonia, amino alcohols, di- and tri-amines, nitrates (e.g., iron nitrate), and any blends thereof.

[0070] Such biocide may be selected from any suitable biocide, for example, biocide including isothiazolin derivatives. Such biocide is generally added in an amount of at least 1 ppm and up to 100 ppm, based on the total weight of the composition at the point of use. The amount of biocide added may be applied depending, for example, on the composition and the planned storage period.

[0071] Such pH adjusters may be selected from any suitable acid such as, for example, hydrochloric acid, nitric acid or sulfuric acid, with nitric acid or sulfuric acid being preferred, and nitric acid being particularly preferred.

[0072] Such surfactants may be selected from any suitable surfactant, such as cationic, anionic, and nonionic surfactants. A specifically preferred example is an ethylenediamine polyoxyethylene surfactant. In general, surfactants may be added in amounts of 100 ppm to 1 wt%, in ppm and wt%, based on the total weight of the composition at the point of use.

[0073] Some of these compounds may be present in the form of a salt, e.g., a metal salt, an acid, etc., or as a partial salt. Equally, some of these compounds may fulfill more than one function when included in a composition suitable for chemical mechanical polishing. For example, iron nitrate, specifically Fe(NO3)3, may act as a chelating agent and / or an oxidizing agent and / or a catalytic agent.

[0074] Specific preferred examples of point-of-use compositions that may be used herein include the following, in ppm and wt % based on the total weight of the point-of-use composition: (i) at least 1.0 wt % and at most 4.0 wt % surface-modified silica particles, as defined herein; (ii) at least 0.001 wt. % and at most 0.10 wt. %, preferably at least 0.01 wt. % and at most 0.05 wt. % Fe(NO3)3; (iii) at least 10 ppm and at most 100 ppm of Kathon ICP II biocide; (iv) optionally, at least 0.01 wt % and at most 0.05 wt % malonic acid; (v) at least 1.0 wt % and at most 8.0 wt % hydrogen peroxide (H2O2); and (vi) Water in such amounts totalling up to 100% by weight; Includes.

[0075] The composition may be prepared by standard methods well known to those skilled in the art. Generally, such preparation involves mixing and stirring steps. It can be carried out either in a continuous or batch manner.

[0076] The composition as described above may be used in a chemical mechanical polishing (CMP) process, in which a substrate is polished. Thus, generally speaking, the present application also relates to: (A) providing a substrate to be polished; and (B) providing a composition as described herein; The present invention provides a method for chemical mechanical polishing, comprising:

[0077] The substrate polished in the present CMP process comprises (i) at least one layer comprising, preferably consisting essentially of, silicon oxide, or at least one layer comprising, preferably consisting essentially of, silicon nitride, and (ii) at least one layer comprising, preferably consisting essentially of, one or more metals or metal alloys. Thus, the present method for chemical mechanical polishing comprises the following steps: (A) providing a substrate comprising: (i) at least one layer comprising, preferably consisting essentially of, silicon oxide; and preferably thereon, (ii) at least one layer comprising, preferably consisting essentially of, one or more metals or metal alloys; and (B) providing a composition as defined herein; Includes.

[0078] As used herein, the term "on" is used to indicate that a layer comprising a metal or metal alloy is essentially placed / located on top of a layer comprising silicon oxide or a layer comprising silicon nitride. Expressed differently and in terms of chemical mechanical polishing, the top layer is the layer adjacent to the polishing pad that is loaded into the CMP polisher before polishing begins.

[0079] As used herein, the term "consisting essentially of" is used to indicate that such a layer may include small amounts of different materials, in wt %, for example in an amount of up to 5 wt % (e.g., in an amount of up to 4 wt % or 3 wt % or 2 wt % or 1 wt % or 0.5 wt % or 0.1 wt %) based on the total weight of such layer.

[0080] Preferably, the silicon oxide included in the layer, which in turn is included in the substrate, may be selected from the group consisting of borophosphosilicate glass (BPSG), plasma enhanced tetraethylorthosilicate (PETEOS), thermal oxide, undoped silicate glass, high density plasma (HDP) oxide, and silane oxide.

[0081] Preferably, the metal or metal alloy contained in the layer, which in turn is contained in the substrate, is selected from the group consisting of tungsten, tantalum, copper, titanium, titanium nitride, aluminum silicon, and any combination thereof, and is preferably tungsten.

[0082] In the CMP process, a polishing pad with a polishing surface is used for the actual polishing of the substrate. Such a polishing pad may be, for example, a woven or non-woven polishing pad, and may include or consist essentially of a suitable polymer. Exemplary polymers include, but are not limited to, polyvinyl chloride, polyvinyl fluoride, nylon, polypropylene, polyurethane, and any blends thereof. The polishing pad and the substrate to be polished are generally mounted in a polishing apparatus, pressed together, and generally rotated non-concentrically, i.e., with different rotation axes, thereby chipping and removing material from the surface or substrate. Thus, the CMP process includes the following steps: (C) providing a chemical mechanical polishing pad having an abrasive surface; (D) contacting the polishing surface of the chemical mechanical polishing pad with the substrate; and (E) polishing the substrate such that at least a portion of the substrate is removed; Further includes:

[0083] The CMP process may be applied in the manufacture of flat panel displays, integrated circuits (ICs), memory or rigid disks, metals, interlayer dielectric devices (ILDs), semiconductors, microelectromechanical systems, ferroelectrics, and magnetic heads. In other words, the substrate polished in the CMP process may be selected from the group consisting of flat panel displays, integrated circuits (ICs), memory or rigid disks, metals, interlayer dielectric devices (ILDs), semiconductors, microelectromechanical systems, ferroelectrics, and magnetic heads.

[0084] example All of the materials used in this example are commercially available from known sources. For example, sodium aluminate (CAS-no. 11138-49-1) can be obtained from Sigma-Aldrich, a subsidiary of Merck KgaA, Darmstadt, Germany. Water glass-based silica particles are obtained in-house at Merck KgaA, Darmstadt, Germany and are commercially available under the trade name Klebosol®. Silica was obtained internally as an aqueous solution with a SiO2 content of approximately 6 wt%, based on the total weight of the aqueous solution. The cation exchange resin used was AMBERJET® 1200 H, supplied by Rohm and Haas Company, Philadelphia, Pennsylvania, USA.

[0085] All water used in the examples was deionized.

[0086] The particle sizes indicated are the Z-average particle sizes, determined based on the specific surface area (SSA) or calculated based on the mass of silica introduced during synthesis.

[0087] Specific surface area (SSA) was determined by titration with aqueous sodium hydroxide as disclosed in GW Sears Jr., Anal. Chem. 1956, 28 (12), 1981-1983.

[0088] Zeta potentials were determined by electrophoretic light scattering (ELS) in aqueous media with the characteristics indicated below using a Zetasizer Nano from Malvern Instruments Limited, Worcestershire, UK.

[0089] The aluminum content was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) on an Agilent 700 ICP-OES available from Agilent, Santa Clara, California, USA, using standard conditions defined by the manufacturer.

[0090] Unless otherwise indicated, all wt% are based on the total weight of the respective aqueous dispersion or solution.

[0091] Example 1 (Comparison) 1776.8 g of an aqueous dispersion (pH=10.3) of 20.0 wt% silica particles having an average particle diameter of 9 nm and a specific surface area of ​​300 m2 / g was heated to boiling, and then 1633.4 g of an aqueous silicic acid solution (5.81 wt% SiO2) was added to the boiling aqueous dispersion of silica particles under stirring for a period of about 2 hours.

[0092] The resulting reaction mixture was kept stirring at boiling temperature for an additional 30 minutes, then allowed to cool to room temperature while stirring to produce 2259 g of intermediate aqueous dispersion (IM-01) of 20.0 wt% silica particles with an average diameter of 9.75 nm. Further properties of intermediate aqueous dispersion (IM-01) are indicated in Table 1 below.

[0093] 1070 g of the so obtained intermediate aqueous dispersion of silica particles (IM-01) was passed through a column of cation exchange resin to recover 904 g of an aqueous dispersion containing 19.15 wt% of silica particles and having a pH of 2-3. The so recovered aqueous dispersion was further diluted with deionized water to give 1154 g of an aqueous dispersion of 15 wt% of silica particles (D-01) having an average particle diameter of 9.75 nm. The properties of the resulting aqueous dispersion (D-01) are given in Table 2 below.

[0094] Example 2 (Comparison) 1070 g of the intermediate aqueous dispersion of silica particles (IM-01) and an aqueous solution of sodium aluminate (3.634 g of sodium aluminate in 115.3 g of water) were heated, separately from each other, to between 50° C. and 60° C. The aqueous solution of sodium aluminate was then added to the intermediate aqueous dispersion (IM-01), heated to 70° C. and then maintained under stirring for a period of about 1 hour.

[0095] The resulting reaction mixture was then allowed to cool to room temperature while stirring to produce 1182 g of an intermediate aqueous dispersion (IM-02) of 18.1 wt % silica particles having an average diameter of 9.75 nm. Further properties of the intermediate aqueous dispersion (IM-01) are indicated in Table 1 below.

[0096] The intermediate aqueous dispersion of silica particles (IM-02) so obtained was then passed through a column of cation exchange resin to recover 956 g of an aqueous dispersion containing 16.8 wt% of silica particles and having a pH of 2-3. The aqueous dispersion of silica particles so recovered was then diluted to give 1072.5 g of an aqueous dispersion of 15.0 wt% of silica particles having an average diameter of 9.75 nm (D-02). The properties of the resulting aqueous dispersion (D-02) are given in Table 2 below.

[0097] Example 3 750 g of an aqueous dispersion of 35.5 wt % silica particles having an average particle diameter of 9 nm and a pH of 10.2 was heated to boiling, then 4.526 g of sodium aluminate and 1224.7 g of an aqueous silicic acid solution (5.91 wt % SiO2) in 578 ml of water were added in parallel to the boiling dispersion under stirring over a period of about 2 hours.

[0098] The resulting reaction mixture was allowed to continue stirring for an additional 30 minutes and allowed to cool to room temperature while stirring to produce 1558 g of an intermediate aqueous dispersion (IM-03) of 21.75 wt % silica particles with a shell comprising aluminate having an average diameter of 9.75 nm. Further properties of intermediate aqueous dispersion (IM-03) are indicated in Table 1 below.

[0099] The intermediate aqueous dispersion of silica particles with aluminate-containing shell (IM-03) thus obtained was passed through a column of cation exchange resin to recover 1165.2 g of an aqueous dispersion of 21.75 wt% silica particles with aluminate-containing shell and having a pH of 2-3, which was subsequently further diluted with deionized water to a total of 1689.5 g of an aqueous dispersion of 15.0 wt% silica particles (D-03). The properties of the resulting aqueous dispersion (D-03) are given in Table 2 below.

[0100] Example 4 750 g of an aqueous dispersion of 35.5 wt % silica particles having an average particle diameter of 9 nm and a pH of 10.2 was heated to boiling, then 9.052 g of sodium aluminate and 1245.5 g of an aqueous silicic acid solution (5.81 wt % SiO2) in 573.5 ml of water were added in parallel to the boiling dispersion under stirring over a period of about 2 hours.

[0101] The resulting reaction mixture was allowed to continue stirring for an additional 30 minutes and allowed to cool to room temperature while stirring to produce 1376.3 g of an intermediate aqueous dispersion (IM-04) of 24.6 wt % silica particles with a shell comprising aluminate having a diameter of 9.75 nm. Further properties of intermediate aqueous dispersion (IM-04) are indicated in Table 1 below.

[0102] The intermediate aqueous dispersion of silica particles with aluminate-containing shell (IM-04) so ​​obtained was then passed through a column of cation exchange resin to recover 1235 g of an aqueous dispersion of 21.3 wt% silica particles with aluminate-containing shell and a pH of 2-3, which was subsequently further diluted with deionized water to a total of 1753.7 g of an aqueous dispersion of 15.0 wt% silica particles with aluminate-containing shell (D-04). The properties of the resulting aqueous dispersion (D-04) are given in Table 2 below.

[0103] [Table 1]

[0104] [Table 2]

[0105] The above results for the zeta potential clearly show that it becomes more negative with increasing concentration of aluminate in the particles.

[0106] Example 5 (Comparison) For the first batch, 1800 g of an aqueous dispersion (pH=9.2) of 35.3 wt% silica particles with an average particle diameter of 35 nm and a specific surface area of ​​74.4 m2 / g was heated to boiling. Then, 710.3 g of an aqueous silicic acid solution (5.87 wt% SiO2) was added to the boiling aqueous dispersion of silica particles under stirring for a period of about 2 hours. The resulting reaction mixture was kept stirring at the boiling temperature for another 30 minutes, and then allowed to cool to room temperature while stirring throughout.

[0107] For the second batch, 1800 g of the same dispersion of silica particles used for the first batch above was heated to boiling. Then, 716.6 g of an aqueous silicic acid solution (5.82 wt% SiO2) was added to the boiling aqueous dispersion of silica particles under stirring over a period of about 2 hours. The resulting reaction mixture was further stirred and then allowed to cool as was done for the first batch.

[0108] The two batches were combined to produce 3594 g of intermediate aqueous dispersion (IM-05) of 32.2 wt % silica particles with an average diameter of 35.75 nm. Further properties of intermediate aqueous dispersion (IM-05) are indicated in Table 3 below.

[0109] 1070 g of the so obtained intermediate aqueous dispersion of silica particles (IM-05) was passed through a column of cation exchange resin to recover 1613 g of an aqueous dispersion containing 30.5 wt% of silica particles and having a pH of 2-3. The so recovered aqueous dispersion was further diluted with deionized water to give 1640 g of an aqueous dispersion of 30.0 wt% of silica particles (D-05) having an average particle diameter of 35.75 nm. The properties of the resulting aqueous dispersion (D-05) are given in Table 4 below.

[0110] Example 6 (Comparison) 1795 g of the intermediate aqueous dispersion of silica particles (IM-05) and an aqueous solution of sodium aluminate (2.508 g of sodium aluminate in 129.1 g of water) were heated, separately from each other, to between 50° C. and 60° C. The aqueous solution of sodium aluminate was then added to the intermediate aqueous dispersion (IM-05), heated to 70° C., and then maintained under stirring for a period of about 1 hour.

[0111] The resulting reaction mixture was then allowed to cool to room temperature while stirring to produce 1847.4 g of an intermediate aqueous dispersion (IM-06) of wt % silica particles having an average diameter of 35.75 nm. Further properties of intermediate aqueous dispersion (IM-06) are indicated in Table 3 below.

[0112] The intermediate aqueous dispersion of silica particles so obtained (IM-06) was then passed through a column of cation exchange resin to recover 1728.4 g of an aqueous dispersion containing 29.7 wt % of silica particles having a pH between 2 and 3. The properties of the resulting aqueous dispersion (D-06) are given in Table 4 below.

[0113] Example 7 1800 g of an aqueous dispersion of 33.6 wt % silica particles having an average particle diameter of 35 nm and a pH of 9.2 was heated to boiling, then 2.627 g of sodium aluminate and 699.2 g of an aqueous silicic acid solution (5.69 wt % SiO2) in 215.8 ml of water were added in parallel to the boiling dispersion under stirring over a period of about 2 hours.

[0114] The resulting reaction mixture was allowed to continue stirring for an additional 30 minutes and allowed to cool to room temperature while stirring to produce 1863 g of an intermediate aqueous dispersion (IM-07) of 31.4 wt % silica particles with a shell comprising aluminate having an average diameter of 35.75 nm. Further properties of intermediate aqueous dispersion (IM-07) are indicated in Table 3 below.

[0115] The intermediate aqueous dispersion of silica particles with aluminate-containing shell (IM-07) thus obtained was passed through a column of cation exchange resin to recover 1647.5 g of an aqueous dispersion of 30.6 wt.% silica particles with aluminate-containing shell and pH between 2 and 3, which was subsequently further diluted with deionized water to a total of 1680.5 g of an aqueous dispersion of 30 wt.% silica particles (D-07). The properties of the resulting aqueous dispersion (D-07) are given in Table 4 below.

[0116] Example 8 1800 g of an aqueous dispersion of 33.6 wt% silica particles with an average particle diameter of 35 nm and a specific surface area of ​​74.4 m2 / g, with a pH of 9.2, was heated to boiling, and then 5.254 g of sodium aluminate and 676.7 g of an aqueous silicic acid solution (5.87 wt% SiO2) in 287.7 ml of water were added in parallel to the boiling dispersion under stirring over a period of about 2 hours.

[0117] The resulting reaction mixture was allowed to continue stirring for an additional 30 minutes and allowed to cool to room temperature while stirring to produce 1973 g of an intermediate aqueous dispersion (IM-08) of 31.2 wt % silica particles with a shell comprising aluminate having a diameter of 35.75 nm. Further properties of intermediate aqueous dispersion (IM-08) are indicated in Table 3 below.

[0118] The intermediate aqueous dispersion of silica particles with aluminate-containing shell (IM-08) so obtained was then passed through a column of cation exchange resin to recover 1762.8 g of an aqueous dispersion of 30.4 wt% silica particles with aluminate-containing shell and a pH of 2-3, which was subsequently further diluted with deionized water to a total of 1786.4 g of an aqueous dispersion of 30 wt% silica particles with aluminate-containing shell (D-08). The properties of the resulting aqueous dispersion (D-08) are given in Table 4 below.

[0119] [Table 3]

[0120] [Table 4]

[0121] Example 9 Chemical mechanical polishing was carried out using the aqueous compositions D-05, D-06, D-07, and D-08 without any additional additives. The compositions may be filtered (0.3 μm pore size) before use in chemical mechanical polishing.

[0122] Polishing was then performed on a 4" silicon nitride wafer using an IC1000™ CMP polishing pad (available from DuPont de Nemours, Wilmington, Delawaware, USA) on a Bruker CP-4 (available from Bruker Corporation, Billerica, Mass., USA). Further polishing conditions were as indicated in Table 5 below.

[0123] [Table 5]

[0124] The results of chemical mechanical polishing are shown in Table 6 below, where PC-1 to PC-2 are comparative examples.

[0125] [Table 6]

[0126] The data clearly show that the addition of an aluminate-containing shell to silica particles can modify - in this case - the removal rate of silicon nitride over a wide range, which in turn will be useful for controlling the removal rate selectivity of the present aluminate-containing shell silica particles.

[0127] Thus, it has been surprisingly found that silica particles containing the present aluminate in general, and anionic silica particles in particular, can modify the zeta potential over a very wide range.It is therefore expected that this approach will also allow modification of the respective removal rates for a large number of different substrates across a wide range of materials - as has already been demonstrated for silicon nitride.The chemical mechanical polishing experiments carried out herein have also demonstrated the general suitability of the present composition for chemical mechanical polishing in the semiconductor industry.

Claims

1. A composition comprising water and core-shell silica particles, wherein the composition is acidic, and the core-shell silica particles comprise a core and a shell, the shell comprising an aluminate portion inside the outer surface of the silica particles.

2. The composition according to claim 1, wherein the composition has a pH of at least 1.5 and up to 5.

5.

3. The composition according to claim 1, wherein the shell containing aluminate has a thickness of at least 0.10 nm and up to 2.0 nm.

4. The composition according to claim 1, wherein the amount of aluminum contained in the aluminate-containing phase is at least 500 ppm and up to 25,000 ppm, in ppm, relative to the respective weight of the aluminate-containing shell.

5. The composition according to claim 1, wherein the composition has a zeta potential of at most 0 mV and at least -30 mV, as determined by electrophoretic light scattering for a composition comprising 15 wt% silica particles in wt% of the total weight of the composition.

6. The composition according to claim 1, wherein core-shell silica particles are included in the composition in wt% of the total weight of the composition, at least 0.1 wt% and up to 50 wt%.

7. The composition according to claim 1, wherein the silica particles contain an alkoxyorganosilane on their surface.

8. The composition according to claim 1, wherein the composition comprises any one or more of the group consisting of biocides, pH adjusters, pH buffers, oxidizing agents, chelating agents, corrosion inhibitors, and surfactants.

9. A method for producing a composition comprising water and core-shell silica particles, wherein the method comprises the following steps: (a) To provide silica particles; (b) Providing an aqueous solution of silicic acid and an aqueous solution of sodium aluminate, and reacting the silicic acid and sodium aluminate in the presence of the silica particles provided in the preceding step under alkaline conditions and at a temperature of at least 40°C to form a shell on the silica particles, thereby producing core-shell silica particles; and (c) Passing the core-shell silica particles produced in the above step through a column of cation exchange resin, This allows us to obtain an acidic composition comprising water and core-shell silica particles, wherein the core-shell silica particles comprise a core and a shell, and the shell comprises an aluminate portion within the outer surface of the silica particles. The method, including the method described above.

10. The method involves the following steps: (d) To provide alkoxyorganosilanes; and (e) The silica particles and alkoxyorganosilane obtained in step (b) are brought into contact with each other, thereby obtaining modified silica particles containing an aluminate portion inside the outer surface of the silica particles. The method according to claim 9, including the method described in claim 9.

11. A method for chemical mechanical polishing, comprising the following steps: (A) To provide a substrate to be polished; (B) To provide a composition according to any one of claims 1 to 8; (C) To provide a chemical mechanical polishing pad having a polishing surface; (D) Bringing the polishing surface of the chemical mechanical polishing pad into contact with the substrate; and (E) Polish the substrate so that at least a portion of it is removed. The method, including the method described above.

12. The substrate provided in step (A) is as follows: (i) at least one layer containing silicon oxide, preferably consisting of silicon oxide, or at least one layer containing silicon nitride, preferably consisting of silicon nitride; and (ii) At least one layer comprising one or more metals or metal alloys, preferably consisting essentially of one or more metals or metal alloys, The method according to claim 11, including the method described in claim 11.

13. (i) The silicon dioxide is selected from the group consisting of borosilicate glass (BPSG), plasma-reinforced tetraethyl orthosilicic acid (PETEOS), thermal oxides, undoped silicate glass, high-density plasma (HDP) oxides, and silane oxides. (ii) One or more metals or metal alloys are selected from the group consisting of tungsten, tantalum, copper, titanium, titanium nitride, aluminum silicon, and any combination thereof, and preferably tungsten. The method according to claim 11.

14. The method according to claim 11, wherein the substrate is selected from the group consisting of flat panel displays, integrated circuits (ICs), memory or rigid disks, metals, interlayer insulating film devices (ILDs), semiconductors, micro-electromechanical systems, ferroelectrics, and magnetic heads.