Amphiphilic abrasive particles and use thereof for chemical mechanical planarization

Abstract

A colloidally stable amphiphilic abrasive particle dispersion comprising amphiphilic abrasive particles is provided. The surface of each colloid-stabilized amphiphilic abrasive particle comprises a hydrophilic portion and a hydrophobic portion. Chemical mechanical planarization (CMP) polishing compositions, methods, and systems using the colloid-stabilized amphiphilic abrasive particle dispersions are also provided. The CMP composition provides a high removal rate of tungsten (W), suppresses the removal rate of silicon oxide (TEOS), and thus has excellent W: TEOS selectivity for chemical mechanical planarization of the tungsten surface.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. [63 / 387,523], which patent application is incorporated herein by reference as if fully set forth. Background of the Invention

[0004] The present invention relates to colloidally stabilized amphiphilic abrasive particles, chemical mechanical planarization (CMP) compositions, chemical mechanical planarization (CMP) methods, and chemical mechanical planarization (CMP) systems.

[0005] More specifically, provided are chemical mechanical planarization (CMP) polishing compositions, methods, and systems using colloidally stabilized amphiphilic abrasive particle dispersions containing amphiphilic abrasive particles. The amphiphilic abrasive particles have a highly nonpolar (or nonpolar) and inert surface toward silicon oxide (TEOS) films (deposited using tetraethyl orthosilicate as a precursor), while being water-dispersible and colloidally stable. In addition, the amphiphilic abrasive particles have a low silanol density (due to conversion of the silanol groups by inert silanes) and a positive charge in the acidic low pH range. The amphiphilic abrasive particles can be used to inhibit CMP polishing on silicon oxide, silicon nitride, or polysilicon.

[0006] In the semiconductor industry, chemical mechanical planarization (CMP) is a well-known technique used in the manufacture of advanced photonic, microelectromechanical and microelectronic materials and devices, such as semiconductor wafers. Semiconductor devices have structured layers and multilayer interconnects consisting of stacked thin films composed of one or more of the following materials: titanium (Ti), titanium nitride (TiN), tantalum (Ta), aluminum-copper (Al-Cu), aluminum-silicon (AlSi), copper (Cu), tungsten (W), doped polysilicon (poly-Si) and various combinations thereof. In addition, transistors or groups of transistors are typically isolated from each other by using trenches filled with insulating materials such as silicon dioxide, silicon nitride and / or polysilicon. The deposition of semiconductor devices is performed using a variety of methods, and a CMP process is performed after each step to ensure that the deposited layers are flat and have a low nanometer-scale surface roughness.

[0007] CMP utilizes a combination of chemical and mechanical forces to achieve planarity on the surface being polished. The chemical action is provided by a chemical composition (also known as a CMP slurry, CMP formulation, or CMP composition). The mechanical action is primarily provided by a polishing pad, which is typically pressed against the surface being polished and mounted on a moving platen. The motion of the platen is typically linear, rotary, or orbital.

[0008] In a typical CMP process, a rotating wafer holder brings the wafer to be polished into contact with a polishing pad. A CMP composition is typically applied between the wafer to be polished and the polishing pad.

[0009] Chemical Mechanical Planarization (CMP) is a process used to manufacture electronic components such as memory chips or microprocessor chips. Structured layers are deposited by various methods, and a CMP process is performed after each step to ensure that the deposited layer is flat and has a low nanometer-scale surface roughness.

[0010] Often, in highly complex structures, different materials are deposited on top of each other, and the CMP process must stop precisely when the material to be polished is removed and the underlying material is exposed. This is achieved, on the one hand, by thoroughly controlling the planarization time, but the CMP slurry must also be formulated in such a way as to exhibit maximum erosion selectivity between the material to be polished and the material to be protected.

[0011] Thus, it is the combination of an effectively high removal rate of the material to be polished and a very low removal rate of the material to be protected that defines the effectiveness of a CMP slurry.

[0012] In addition to various additives and various pH values that can be used to adjust the selectivity of the slurry, the CMP abrasive material largely determines the removal rate and selectivity of the slurry, as disclosed in US Pat. No. 9,028,572.

[0013] This is particularly true for W-CMP applications, for example, where the slurry should exhibit a high removal rate for oxidized W-metal, but a very low removal rate for silicon oxide, which should remain substantially intact.

[0014] Even after known surface modification treatments, typical CMP abrasives have many polar groups on their surfaces that can form electrostatic or hydrogen bonds with silica and other polar surfaces, leading to undesirably high silica removal rates. Consequently, W-CMP slurry formulation designers strive to achieve high selectivity with existing abrasive materials.

[0015] Currently available CMP abrasives do not exhibit inherently high selectivity. They must be mixed with numerous additives to achieve the desired selectivity, which can, on the other hand, present problems with slurry stability or reduced removal rates of the material to be polished.

[0016] The present invention provides amphiphilic abrasive particles having a highly non-polar and inert surface toward silicon oxide; and also provides CMP polishing compositions, methods, and systems using the amphiphilic abrasive particles. These and other advantages of the present invention, as well as additional inventive features, will become apparent from the description of the invention provided herein. SUMMARY OF THE INVENTION

[0018] The present invention provides a colloidally stabilized amphiphilic abrasive dispersion comprising amphiphilic abrasive particles, and also provides a CMP composition, method, and system using the colloidally stabilized amphiphilic abrasive dispersion.

[0019] In one aspect, colloidally stabilized amphiphilic abrasive particles are provided. The amphiphilic abrasive particles have both a hydrophilic portion and a hydrophobic portion on the surface, thereby having a surface that is highly non-polar and inert to silicon oxide. The amphiphilic abrasive particles in the dispersion are colloidally stabilized.

[0020] Each hydrophilic moiety independently includes, but is not limited to, at least one selected from the following: an N-containing group selected from amine and substituted amines; amino, ammonium; ammonium and substituted ammonium groups (which include but are not limited to alkylammonium groups containing alkyl groups having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms); sulfonium; phosphonium; sulfate; sulfonate; phosphate; hydroxyl; epoxy; carboxyl; ether; polyether; or polyether group; preferably a nitrogen-containing group.

[0021] Each hydrophilic moiety independently includes, but is not limited to, at least one selected from amine, amino, ammonium, alkylammonium groups containing an alkyl group having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms.

[0022] For example, the hydrophilic portion may be an amino group; and the hydrophobic portion may be a trimethylsilyl group.

[0023] The colloidally stabilized amphiphilic abrasive particles have a ratio of hydrophilic to hydrophobic portions ranging from 1.00:0.01 to 1.00:10.00, 1.00:0.25 to 1.00:5.00, 1.00:0.30 to 1.00:3.00, 1.00:0.40 to 1.00:2.50, or 1.00:0.50 to 1.00:2.00.

[0024] The colloidally stabilized amphiphilic abrasive particles have any size distribution, including but not limited to unimodal, bimodal or multimodal; any shape, including but not limited to spherical, elongated or branched, and a mean particle size (MPS) in the range of 1-500 nm, 2-300 nm, 5-200 nm, 10-150 nm or 20-100 nm, dispersed in a solvent comprising water. The MPS can be measured by dynamic light scattering (DLS).

[0025] In another aspect, a method for preparing colloidally stabilized amphiphilic abrasive particles is provided, comprising the steps of:

[0026] a. providing a base abrasive particle having a reactive M-OH group on the surface, and the base abrasive particle is dispersed in a solvent;

[0027] b. modifying the surface of the base abrasive particles with a first step surface modifier having at least one hydrophilic group and at least one first reactive group capable of forming a covalent bond with the reactive M-OH group to obtain a step-modified abrasive particle;

[0028] c. modifying the surface of the one-step modified abrasive particle with a second-step surface modifier having at least one hydrophobic group and at least one second reactive group capable of forming a covalent bond with the reactive X-OH groups on the surface of the one-step modified abrasive particle to obtain an amphiphilic abrasive particle;

[0029] in

[0030] M in the reactive M-OH group is selected from metals or semimetals, including but not limited to Si, Ce, Al, Zr, hybrids and / or mixtures of metals and semimetals;

[0031] X in the reactive X-OH group is selected from Si, Ce, Al, Zr, C, P, N, hybrids and / or mixtures thereof; and

[0032] The solvent is selected from the group consisting of water, alcohols, ketones, esters, ethers, glycols, and combinations thereof.

[0033] The at least one first reactive group and the at least one second reactive group are independently selected from silicon alkoxides, silicon halides (preferably chlorides), oxime salts, acetates, silicon hydroxides; and combinations thereof; preferably silicon methoxide and silicon ethoxide.

[0034] Preferably, the first-step surface modifier includes, but is not limited to, a silane containing at least one hydrophilic group, and the second-step surface modifier includes, but is not limited to, a silane containing at least one hydrophobic group.

[0035] The at least one hydrophilic group includes, but is not limited to, an N-containing group selected from amines; substituted amines; amino groups; ammonium; ammonium groups and substituted ammonium groups (which include, but are not limited to, alkylammonium groups containing alkyl groups having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms); sulfonium; phosphonium; sulfate; sulfonate; phosphate; hydroxyl; epoxy; carboxyl; ether; polyether groups; combinations thereof; preferably an N-containing group selected from amine, amino, ammonium, or alkylammonium groups.

[0036] The first step surface modifiers are also capable of reacting among themselves to form a covalently bonded polymer shell (crosslinked shell) around the base abrasive particles.

[0037] The second-step surface modifier includes, but is not limited to, silanes having at least one hydrophobic group, including, but not limited to, methyl, ethyl, propyl, butyl, phenyl, benzyl, tolyl, or xylyl.

[0038] Second-step surface modifiers include, but are not limited to, silanes having at least two, preferably at least three, hydrophobic groups comprising an alkyl group having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms; or an aryl group having <20 carbon atoms or <10 carbon atoms; and combinations thereof.

[0039] The total amount of the first-stage surface modifier and the second-stage surface modifier includes, but is not limited to, 0.01-1.0 mmol / g (abrasive mass calculated as dry matter), 0.025-0.8 mmol / g, 0.05-0.5 mmol / g, or 0.1-0.4 mmol / g.

[0040] The first step surface modifier includes but is not limited to amino-polyether silane, betaine-type silane, ethoxysilane or 3-aminopropyl derivative of methoxysilane, for example, 3-aminopropylmethyldimethoxysilane, and combinations thereof; preferably 3-aminopropylmethyldimethoxysilane.

[0041] The first step surface modifier may be used in any mixture with other functional or non-functional reactants such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and combinations thereof.

[0042] Examples of second-step surface modifiers include, but are not limited to, trimethylmethoxysilane, trimethylethoxysilane, dimethylphenylmethoxysilane, diphenylsilanediol, diphenyldimethoxysilane, methylphenyldimethoxysilane, dimethyldimethoxysilane, hexamethyldisilazane, hexamethyldisiloxane, dimethylethylmethoxysilane, dimethyloctylmethoxysilane, dimethyloctadecylchlorosilane, dimethylhexadecylmethoxysilane, dimethyl(methylphenyl)methoxysilane, potassium trimethylsilanol, triethylmethoxysilane, and combinations thereof.

[0043] Preferred second-stage surface modifiers are trimethylmethoxysilane, trimethylethoxysilane, and combinations thereof.

[0044] In yet another aspect, a CMP polishing composition is provided, comprising the colloidally stabilized amphiphilic abrasive particles dispersed in water; a water-soluble solvent including, but not limited to, alcohols, ethers, ketones; and mixtures thereof.

[0045] The CMP polishing composition may optionally comprise at least one of the following:

[0046] organic and inorganic salts, as colloidal stabilizers;

[0047] catalysts, including but not limited to fluoride ions, metal salts, or metal alkoxides, such as titanium isopropoxide;

[0048] Acid / base pH buffers;

[0049] biocides;

[0050] oxidants;

[0051] catalyst;

[0052] chelating agents;

[0053] Sagging and erosion inhibitors;

[0054] and

[0055] Corrosion inhibitor.

[0056] In another aspect, a method of chemical mechanical polishing (CMP) of a substrate having at least one tungsten-containing surface using the above-described chemical mechanical polishing (CMP) composition is provided.

[0057] Specifically, CMP compositions using colloidally stabilized amphiphilic abrasive particle dispersions provide high removal rates of tungsten (W), suppress the removal rate of TECS, and thus have excellent W:TEOS selectivity for chemical mechanical planarization of tungsten surfaces (i.e., W CMP), especially at acidic low pH. Detailed Description of the Invention

[0059] The present invention relates to colloidally stabilized amphiphilic abrasive particles, and provides chemical mechanical polishing (CMP) compositions (also referred to as slurries or formulations), methods, and systems using colloidally stabilized amphiphilic abrasive particle dispersions containing the amphiphilic abrasive particles.

[0060] The present invention provides colloidally stable amphiphilic abrasive dispersions for use in CMP compositions. Colloidally stable means that the abrasive particles of the present invention do not gel, precipitate, or exhibit a change in average particle size (MPS measured by DLS) of more than 10% within 30 days when stored as a dispersion (20 wt% solids) at room temperature in a solvent including, but not limited to, water; water-miscible solvents (including, but not limited to, alcohols, ethers, ketones); and mixtures thereof, at a pH resulting in a zeta potential of >+25 mV or <-25 mV.

[0061] The amphiphilic abrasive particles in the dispersion have a surface that is highly non-polar and inert to silica, while being colloidally stable, where colloidally stable means solvent dispersible, wherein the solvent includes but is not limited to water; water-soluble solvents (including but not limited to alcohols, ethers, ketones); and mixtures thereof.

[0062] The abrasive particles have silanol groups converted with an inert silane; thus, they have a low silanol density and a positive charge in the acidic low pH range. The abrasive particles provide high selectivity, particularly for tungsten CMP (W CMP) applications.

[0063] These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.

[0064] Abrasive particles:

[0065] Colloidally stabilized amphiphilic abrasive particles are obtained by the two-step surface modification or treatment method of the present invention.

[0066] Base or unmodified abrasive particles (leftmost circle), such as silica, have a very hydrophilic surface covered with Si-OH (silanol) and Si-O-Si- (siloxane) groups and can carry either a positive or negative charge depending on the pH.

[0067] The first step of surface modification is to covalently react Si-OH groups on the surface of the base abrasive particles with a first step surface modifying agent (such as aminosilane) to attach hydrophilic (or polar) and / or charged groups to the surface of the abrasive particles.

[0068] Furthermore, depending on the amount of first-stage surface modifier applied and due to reactions between the first-stage surface modifiers, the first-stage surface modification may also result in the formation of a continuous polysiloxane cross-linked or network shell around the base abrasive particles.

[0069] Thus, the first step of surface modification can result in partial surface modification, thereby leaving a portion of the base abrasive surface unmodified, or result in the formation of a polysiloxane crosslinked shell that covers and modifies the entire surface of the base abrasive particle, as illustrated in the examples below.

[0070]

[0071] Example A shows a surface modification in which a crosslinked shell (e.g., a polyorganosiloxane shell) is formed around the base abrasive particles due to a reaction between the surface modifiers themselves in the first step, resulting in a covalently bonded polymeric crosslinked shell around the base abrasive particles after the first modification step. This shell still contains residual silanol groups on the surface, which can react with the second surface modifier in the second modification step.

[0072] Example B shows a surface modification in which only a portion of the original silanol groups from a portion of the base abrasive particle surface react with the first-step surface modifier, with some of the originally present silanol groups remaining unreacted. These silanol groups and potential new silanol groups generated by surface modification step one can then react with the second-step surface modifier in modification step two.

[0073] If the surface modification in the first step (step 1) is incomplete in practice, a large number of residual Si-OH groups (residual Si-OH groups) may remain on the surface after modification due to cost or space constraints. Furthermore, the modified silanes have little access to the polar Si-O-Si network. Consequently, there may be sufficient "polarity" on the surface to foster unwanted interactions with the polar silicon oxide, even though the silicon oxide should not be attacked by the abrasive particles.

[0074] Using a second surface modification step (step 2), the remaining Si-OH groups can be modified by a second-step surface modifier, which is typically a small, highly hydrophobic reactant, to attach hydrophobic (or non-polar) groups to the surface of the abrasive particles.

[0075] Surface modification of silica and other oxides with small hydrophobic molecules such as trimethylchlorosilane is used to prepare laser printer colorants or as an anti-caking agent for hydrophobic pigments. Modified silica is rendered completely hydrophobic by the modification, making it virtually impossible to maintain a stable colloidal dispersion in water. In fact, these treatments are also used to impart water-repellent properties to particles.

[0076] Furthermore, if silica is modified with small hydrophobic molecules such as trimethylchlorosilane in an aqueous dispersion, the colloidal dispersion will likely become unstable and the silica will agglomerate and eventually precipitate.

[0077] As described below, the present invention overcomes all of these negative effects.

[0078] In the present invention, the first step of surface modification introduces permanent hydrophilic (polar) groups (which can be ionic and / or non-ionic) onto the surface of the base particles to have good compatibility with water and high colloidal stability, especially when the first step of surface modification includes charged groups that cause similarly charged particles to repel each other.

[0079] After the first step of surface modification, the abrasive is ready for the second step of modification. It is preferred to use small molecules in the second step of modification so that they can reach all accessible silanol groups and effectively occupy the space on the abrasive surface and shield a substantial portion of the underlying hydrophilic surface moieties. It is preferred that a majority (e.g., >50%, >60%, or >70%) of the accessible silanol groups and other polar moieties on the abrasive surface are converted or shielded.

[0080] The hydrophilic (polar) groups in the first modification step are typically attached to alkyl spacers of a certain length (usually >2 carbon atoms) and exhibit sufficient mobility so that they cannot be completely covered by the second surface modification step and maintain high colloidal stability.

[0081] After the second-step surface modification, most of the accessible silanol groups on the base silica surface are converted by reaction with the first-step surface modifier used, such as silanes, or are shielded from any interaction with the surface to be polished. Thus, the properties of the amphiphilic abrasive surface can be completely changed to a defined or balanced mixture of introduced hydrophilic moieties (from the first surface treatment) and hydrophobic moieties (from the second surface treatment), and can be substantially free of original hydrophilic moieties that could interact undesirably with, for example, TEOS surfaces in CMP applications.

[0082] The total amount of the first-step surface modifier and the second-step surface modifier ranges from 0.01 to 1.0 mmol / g (abrasive mass calculated as dry matter), 0.025 to 0.8 mmol / g, 0.05 to 0.5 mmol / g, or 0.1 to 0.4 mmol / g.

[0083] Since the two-step modified abrasive particles have distinct hydrophobic and hydrophilic portions distributed throughout their surface, they can be referred to as amphiphilic (mixed hydrophilic and hydrophobic) particles. Amphiphilic substances generally have the property of being compatible with both polar and non-polar liquids, and they can act as emulsifiers. Therefore, it is believed that these amphiphilic abrasive particles can also show advantages in applications such as spin-on carbon CMP and CMP applications where other non-polar components play a role.

[0084] By selecting the ratio of the hydrophilic (polar) portion from the first modification step and the hydrophobic (non-polar) portion from the second modification step, the interaction of the amphiphilic abrasive particles of the present invention with the surface to be protected during CMP can be reduced to a very low level, thereby providing polishing selectivity, for example, excellent "silicon oxide stop" performance in W-CMP. The amphiphilic abrasive particles of the present invention also have outstanding colloidal stability.

[0085] The ratio of the hydrophilic (polar) portion from the first modification step to the hydrophobic (non-polar) portion from the second modification step can be 1.00:0.01 to 1.00:10.00, 1.00:0.25 to 1.00:5.00, 1.00:0.30 to 1.00:3.00, 1.00:0.40 to 1.00:2.50, or 1.00:0.50 to 1.00:2.00.

[0086] Further details are described regarding the method of obtaining colloidally stabilized amphiphilic abrasive particles.

[0087] The starting base or unmodified abrasive grain (or abrasive) has reactive M-OH groups on its surface, wherein M is a metal or semimetal, including but not limited to Si, Ce, Al, Zr, and hybrids / mixtures of metals and / or semimetals. Examples of base or unmodified abrasive grains include but are not limited to silica, ceria, hybrids of silica and ceria (silica modified by ceria or ceria modified by silica, zirconium silicate, carbide, or nitride).

[0088] Preferred base abrasives are SiO2-containing abrasives, such as pure silica, doped silica or multi-component silicates.

[0089] A more preferred base abrasive is non-spherical colloidal silica as described in WO2022226471 A1.

[0090] The base abrasives may be in dispersed, agglomerated or dry form, as long as they can be processed as described through the two surface modification steps and produce a colloidally stable amphiphilic abrasive dispersion.

[0091] The base abrasive should be dispersed in a suitable solvent (or mixture) and substantially deagglomerated to the desired size distribution prior to the first surface modification step; typically having at least one dimension <500 nm, preferably <200 nm, more preferably <150 nm prior to surface modification.

[0092] The base particles must be dispersed in a solvent or solvent mixture that allows the first and second step surface modification to proceed in a colloidally stable state. The solvent composition can be varied and can be changed after the first step and before and / or after the second step to obtain a smooth process and a colloidally stable amphiphilic abrasive dispersion.

[0093] Typical and preferred solvent mixtures are water / alcohol mixtures in various ratios in which the surface modifier is dissolved. Ethanol is the most preferred alcohol.

[0094] Other possible organic solvents that can be used in mixture with water are ketones, esters, ethers, glycols and alcohols. Examples of suitable organic solvents are acetone, diethyl ether, propylene glycol dimethyl ether, propylene glycol monoacetate, isopropanol, n-propanol, propylene glycol monomethyl ether.

[0095] Pure water is possible as a solvent for the modification steps, but is not preferred, especially for the second modification step, because the hydrophobic modifier is not easily soluble or dispersed in water, which may lead to longer processing times and uneven results.

[0096] It is preferred to remove the non-volatile organic components from the abrasive dispersion at the latest after the second surface modification step and to retain essentially only water as the sole dispersant in the final product.

[0097] Surface modification can be carried out at any suitable pH, depending on the nature of the base abrasive and the reactants.

[0098] Generally, alkaline conditions are preferred to facilitate the reaction between the abrasive particle surface groups and the reactants, however good results can also be obtained under acidic conditions.

[0099] It is preferred to use a pH adjusting agent that can be removed from the reaction mixture, for example by applying a vacuum, or to use a pH adjusting agent that is subsequently a desired component of the CMP slurry to be formulated. Typical preferred pH adjusting agents are HNO3 or NH3.

[0100] Catalysts may also be used to promote the reaction. Suitable catalysts include, but are not limited to, fluoride ions or metal salts or metal alkoxides, such as titanium isopropoxide.

[0101] The first step surface modifier can be any reactant that can form a covalent bond with the surface M-OH group of the unmodified base abrasive, wherein the M-OH group is selected from a metal or semimetal, including but not limited to Si, Ce, Al, Zr and a hybrid and / or mixture of metal and semimetal. The M-OH group is used as a linking group, and M is used as a connecting atom. The connecting atom M herein is an atom that connects or bonds the grinding surface and the hydrophilic portion through a covalent bond.

[0102] The first step surface modifier can be a single reactant or a mixture of reactants.

[0103] The first step surface modifier is a hydrophilic modifier comprising a hydrophilic group, which can be covalently linked to a linking group, preferably Si, through an alkyl and / or aryl group which may also contain heteroatoms.

[0104] The hydrophilic group can be anionic, cationic, zwitterionic (inner salt) or nonionic in nature. Depending on the pH of the solvent, the hydrophilic group can be anionic, cationic or nonionic. Preferred hydrophilic groups are nitrogen-containing groups, such as amine, amino, ammonium or alkylammonium groups.

[0105] Examples of hydrophilic groups include, but are not limited to, amine, substituted amine, amino, ammonium and substituted ammonium groups, sulfonium, phosphonium, sulfate, sulfonate, phosphate, hydroxyl, epoxy, carboxyl, ether, or polyether groups.

[0106] Examples of first-stage surface modifiers include, but are not limited to, silanes containing a hydrophilic group and at least one reactive group capable of forming a covalent bond with an abrasive surface group. Examples are amino-polyether silanes and betaine-type silanes.

[0107] There may be more than one hydrophilic group attached to a linking group that reacts with the polishing surface. The more than one hydrophilic group may be of the same or different types, for example, anionic + cationic, anionic + nonionic, or cationic + nonionic. The first step surface modifier as a hydrophilic surface modifier has at least one reactive group capable of forming a covalent bond with a polishing surface group.

[0108] The reactive group of the surface modifier can be any group that can be cleaved under processing conditions, thereby promoting a covalent bond between the abrasive surface and the modifier, or can react directly with a group on the abrasive surface.

[0109] Examples of typical reactive groups include, but are not limited to, silicon alkoxides, silicon halides (preferably chlorides), oxime salts, acetates, or silicon hydroxides. Preferred examples are silicon methoxides and silicon ethoxides.

[0110] A preferred first-stage surface modifier is a 3-aminopropyl derivative of an ethoxysilane or methoxysilane, for example, 3-aminopropylmethyldimethoxysilane.

[0111] The first step surface modifier can also be used in any mixture with other functional or non-functional reactants such as tetramethoxysilane, tetraethoxysilane methyltrimethoxysilane, methyltriethoxysilane or a combination thereof. The ratio of the first step modifier to the functional or non-functional reactant includes, but is not limited to, 9.9:1 to 0.1:9.9, preferably 9:1 to 1:9.

[0112] After the first modification step, a one-step modified abrasive grain is obtained. The surface of the one-step modified abrasive grain contains reactive groups of X-OH groups, wherein X in the reactive X-OH groups includes, but is not limited to, Si, Ce, Al, Zr, C, P, N, hybrids thereof, and / or mixtures thereof. The X-OH group serves as a linking group, with X serving as a linking atom. The linking atom herein is an atom that connects or bonds the abrasive surface to the hydrophobic portion via a covalent bond.

[0113] The second-step surface modifier includes, but is not limited to, reactants capable of forming covalent bonds with the surface X-OH groups of the first-step modified abrasive particles.

[0114] The second-stage surface modifier can be a single reactant or a mixture of reactants.

[0115] The second-step surface modifier is a hydrophobic modifier comprising a hydrophobic group.

[0116] The reactive group of the second surface modifier toward the abrasive surface can be any group that is cleavable under processing conditions, thereby promoting a covalent bond between the first-stage modified abrasive particle surface and the second-stage surface modifier, or can directly react with a group on the first-stage modified abrasive particle surface.

[0117] Examples of typical reactive groups include, but are not limited to, silicon alkoxides, silicon halides (preferably chlorides), oxime salts, acetates or silicon hydroxides, silazanes, silanol esters (e.g., KOSi(CH3)3) or siloxanes. Preferred examples are silicon methoxides and silicon ethoxides and silazanes.

[0118] The second-stage surface modifier typically does not have functional groups on its alkyl or aryl groups.

[0119] The second step surface modifier comprises at least 2 alkyl and / or aryl groups that are covalently bonded to the connection atom X (for example, silicon atom), preferably 3 alkyl and / or aryl groups. The length of alkyl group is less than 20 carbon atoms, preferably less than 10 carbon atoms, more preferably less than 4 carbon atoms. The aryl group can carry an aliphatic substituent and has less than 20 carbon atoms, preferably less than 10 carbon atoms, more preferably less than 8 carbon atoms in total. The example of the connection atom can be Si, Ce, Al, Zr, C, P and N atom.

[0120] Examples of second-step surface modifiers include, but are not limited to, silanes containing a hydrophobic group and at least one reactive group capable of forming a covalent bond with the first-step modified abrasive particle surface groups.

[0121] Examples of second-step surface modifiers include, but are not limited to, trimethylmethoxysilane, trimethylethoxysilane, dimethylphenylmethoxysilane, diphenylsilanediol, diphenyldimethoxysilane, methylphenyldimethoxysilane, dimethyldimethoxysilane, hexamethyldisilazane, hexamethyldisiloxane, dimethylethylmethoxysilane, dimethyloctylmethoxysilane, dimethyloctadecylchlorosilane, dimethylhexadecylmethoxysilane, dimethyl(methylphenyl)methoxysilane, potassium trimethylsilicate, triethylmethoxysilane, and mixtures thereof.

[0122] For the second-stage surface modifier, it is preferred to use a short-chain small molecule with only one reactive group, such as trimethylmethoxysilane, trimethylethoxysilane, or a mixture thereof. If the reactant from the second-stage surface modifier does not have the opportunity to react with the abrasive surface, and the two reactants react with each other, hexamethyldisiloxane is formed. This is an organic solvent with a sufficiently low boiling point that this byproduct can be easily removed by distillation. Therefore, even a large excess of reactant can be managed during the reaction without the problem of unwanted byproducts and the accumulation of unreacted reactants.

[0123] The first and second surface modification steps can be performed completely separately, with undefined pauses and / or other operations such as distillation, concentration, filtration, purification, ion exchange, etc. in between.

[0124] The first and second surface modification steps can be performed under the same or different conditions, such as at different pH values, in different solvent mixtures, at different temperatures, with different catalysts, and for different reaction times. Each modification step is a separate process that can and should be run under optimal conditions for the individual reaction.

[0125] The first and second surface modification steps can also be performed one after the other without any changes in pH, solvent, temperature or catalyst.

[0126] It is preferred to carry out the first and second step modifications one after the other, and it is preferred not to start the second step surface modification until it is confirmed that the first step surface modification is almost complete (e.g., by checking by NMR or IR measurement). This is to ensure that after the first step surface modification, the abrasive surface is sufficiently hydrophilic to remain stable during the reaction with the hydrophobic second modifying agent.

[0127] After each surface modification step, there may be an optional aging step at a defined temperature between 0° C. and the boiling point of the solvent mixture used.

[0128] After the second surface modification, an optional aging step is preferred to ensure completion of the reaction, and then the volatile organic components of the reaction mixture are removed and optionally replaced with water.

[0129] This can be accomplished by any suitable method, such as distillation or membrane filtration.It is preferred that the total non-volatile solids content of the reaction mixture is adjusted to 10-50% solids, more preferably 20-40% solids, most preferably 30-40% solids.

[0130] After the second surface modification, further modifications can be performed, such as filtration, classification, ion exchange, and addition of other compounds. This can be done before or after the removal of VOCs.

[0131] The second surface modification is preferably performed to an extent such that the colloidal stability of the abrasive dispersion is not affected and a minimum silicon oxide removal rate is achieved.

[0132] A minimum total amount of surface modifier (first and second steps) is present to provide good removal rates and selectivity.

[0133] A minimum level of hydrophilic modifier is required in the first modification to ensure colloidal stability.

[0134] The minimum second-stage hydrophobic modifier content is determined by high or maximum selectivity. Too much hydrophobic modifier will cause agglomeration.

[0135] The amphiphilic abrasive particles of the present invention are colloidally stabilized amphiphilic abrasive particles having a surface comprising a hydrophilic portion and a hydrophobic portion. For example, the hydrophilic portion may be an amino group; and the hydrophobic portion may be a trimethylsilyl group.

[0136] The colloidally stabilized amphiphilic abrasive particles have a ratio of hydrophilic to hydrophobic portions ranging from 1.00:0.01 to 1.00:10.00, 1.00:0.25 to 1.00:5.00, 1.00:0.30 to 1.00:3.00, 1.00:0.40 to 1.00:2.50, or 1.00:0.50 to 1.00:2.00.

[0137] A colloidally stabilized amphiphilic abrasive dispersion refers to amphiphilic abrasive particles dispersed in a solvent comprising water having any size distribution (including but not limited to unimodal, bimodal or multimodal); any shape (including but not limited to spherical, elongated or branched) and a size in the range of 1-500 nm, 2-300 nm, 5-200 nm, 10-150 nm or 20-100 nm.

[0138] Thus, provided herein are colloidally stabilized amphiphilic abrasive particles, wherein the surface of the colloidally stabilized amphiphilic abrasive particles comprises a hydrophilic portion and a hydrophobic portion; and the colloidally stabilized amphiphilic abrasive particles are highly non-polar.

[0139] wherein each hydrophilic group comprises at least one group selected from the following groups: an N-containing group selected from amines and substituted amines; amino groups; ammonium groups; ammonium groups and substituted ammonium groups (including but not limited to alkylammonium groups containing alkyl groups having <20 carbon atoms; <10 carbon atoms or <4 carbon atoms); sulfonium; phosphonium; sulfate groups; sulfonate groups; phosphate groups; hydroxyl groups; epoxy groups; carboxyl groups; ethers; polyethers; or polyether groups; preferably N-containing groups; and each hydrophilic moiety independently comprises at least one group selected from alkyl groups having <20 carbon atoms, <10 carbon atoms or <4 carbon atoms; aromatic groups having <20 carbon atoms, <10 carbon atoms or <8 carbon atoms; and combinations thereof.

[0140] In addition, more than one hydrophilic moiety and / or more than one hydrophobic moiety can be attached to a linking atom selected from Si, Ce, Al, Zr, C, P, and N atoms; wherein the linking atom connects or bonds the hydrophilic moiety and / or the hydrophobic moiety to the surface of each colloidally stabilized amphiphilic abrasive particle via a covalent bond.

[0141] The colloidally stabilized amphiphilic abrasive particles have a hydrophilic portion which is a silane having an amino group; and a hydrophobic portion which is a trimethylsilyl group; and the colloidally stabilized amphiphilic abrasive particles have a surface which is highly non-polar and inert to silica.

[0142] The colloidally stabilized amphiphilic abrasive particles have a ratio of hydrophilic to hydrophobic portions ranging from 1.00:0.01 to 1.00:10.00, 1.00:0.25 to 1.00:5.00, 1.00:0.30 to 1.00:3.00, 1.00:0.40 to 1.00:2.50, or 1.00:0.50 to 1.00:2.00.

[0143] The surface of each colloidally stabilized amphiphilic abrasive particle may be a covalently bonded polymer cross-linked shell, such as a polyorganosiloxane cross-linked shell.

[0144] The present invention also provides a method for preparing colloidally stabilized amphiphilic abrasive particles, comprising the following steps:

[0145] a. providing a base abrasive particle having a reactive M-OH group on its surface, and the base abrasive particle is dispersed in a solvent;

[0146] b. modifying the surface of the base abrasive particles with a first step surface modifier having at least one hydrophilic group and at least one first reactive group capable of forming a covalent bond with the reactive M-OH group or reacting directly therewith to obtain a step-modified abrasive particle;

[0147] c. modifying the surface of the one-step modified abrasive particle with a second-step surface modifier having at least one hydrophobic group and at least one second reactive group capable of forming a covalent bond with or directly reacting with an X-OH group on the surface of the one-step modified abrasive particle to obtain an amphiphilic abrasive particle;

[0148] in

[0149] M in the reactive M-OH group is selected from metals or semimetals, including but not limited to Si, Ce, Al, Zr, and hybrids and / or mixtures of metals and semimetals;

[0150] X in the reactive X-OH group is selected from Si, Ce, Al, Zr, C, P, N, hybrids and / or mixtures thereof; and

[0151] The solvent is selected from the group consisting of water, alcohols (preferably ethanol), ketones, esters, ethers, glycols, and combinations thereof; preferably a combination of water and alcohols.

[0152] The at least one first reactive group or the at least one second reactive group is independently selected from silicon alkoxides, silicon halides (preferably chlorides), oxime salts, acetates, silicon hydroxides; and combinations thereof; preferably silicon methoxides and silicon ethoxides.

[0153] The first-stage surface modifier is selected from silanes having at least one hydrophilic group, and the second-stage surface modifier is selected from silanes having at least one hydrophobic group.

[0154] The first step surface modifier comprises at least one hydrophilic group including but not limited to: an N-containing group selected from amine and substituted amine; amino, ammonium; ammonium and substituted ammonium groups (which include but are not limited to alkylammonium groups containing alkyl groups having <20 carbon atoms; <10 carbon atoms or <4 carbon atoms); sulfonium; phosphonium; sulfate; sulfonate; phosphate; hydroxyl; epoxy; carboxyl; ether; polyether; or polyether group; preferably an N-containing group selected from amine, amino, ammonium and alkylammonium groups.

[0155] Due to the reaction between the first-stage surface modifiers themselves, a crosslinked shell (covalently bonded polymer shell, such as a polyorganosiloxane shell) can be formed around the base abrasive particles in step b. This shell still contains residual X-OH groups on the surface, which can react with the second surface modifier in step c.

[0156] The second-step surface modifier comprises at least one hydrophobic group including, but not limited to, alkyl groups having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms; and aryl groups having <20 carbon atoms, <10 carbon atoms, or <8 carbon atoms.

[0157] The second-step surface modifier comprises at least two, preferably at least three, hydrophobic groups comprising alkyl groups having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms; aryl groups having <20 carbon atoms, <10 carbon atoms, or <8 carbon atoms; and combinations thereof.

[0158] The total amount of the first-step surface modifier and the second-step surface modifier ranges from 0.01 to 1.0 mmol / g (abrasive mass calculated as dry matter), 0.025 to 0.8 mmol / g, 0.05 to 0.5 mmol / g, or 0.1 to 0.4 mmol / g.

[0159] The method further comprises, after step c, step d: maintaining water as the only dispersion medium after the second step surface modification.

[0160] Also provided herein is a CMP polishing composition comprising the colloidally stabilized amphiphilic abrasive particles dispersed in water; a water-soluble solvent including but not limited to alcohols, ethers, ketones; and mixtures thereof.

[0161] The CMP polishing composition may optionally comprise at least one of the following:

[0162] organic and inorganic salts, as colloidal stabilizers;

[0163] catalysts, including but not limited to fluoride ions, metal salts, or metal alkoxides, such as titanium isopropoxide;

[0164] Acid / base pH buffers;

[0165] biocides;

[0166] oxidants;

[0167] catalyst;

[0168] chelating agents;

[0169] Sagging and erosion inhibitors;

[0170] and

[0171] Corrosion inhibitor.

[0172] In addition, a method of chemical mechanical polishing (CMP) of a substrate having at least one surface containing tungsten using the chemical mechanical polishing (CMP) composition is provided.

[0173] Specifically, CMP compositions using colloidally stabilized amphiphilic abrasive particle dispersions provide high removal rates of tungsten (W), suppress the removal rate of TEOS, and thus have excellent W:TEOS selectivity for chemical mechanical planarization of tungsten surfaces (i.e., W CMP), especially at acidic low pH.

[0174] CMP Method

[0175] In the examples given below, CMP experiments were carried out using the procedures and experimental conditions given below.

[0176] Glossary

[0177] Components

[0178] TEOS: Silicon oxide film by chemical vapor deposition (CVD) using tetraethyl orthosilicate as a precursor

[0179] Weight %: weight percentage (of the listed ingredients)

[0180] Removal rate (RR) = (film thickness before polishing - film thickness after polishing) / polishing time.

[0181] Polishing pad: A polishing pad IC1010 provided by DOW, Inc. was used during CMP.

[0182] Trimming disk: 3M A122 disk provided by 3M Company was used.

[0183] parameter

[0184] General

[0185] or A: Angstrom - unit of length

[0186] BP: back pressure, in psi

[0187] CMP: Chemical Mechanical Planarization = Chemical Mechanical Polishing

[0188] CS: Carrier speed

[0189] DF: Downward force: The pressure applied during CMP, in psi

[0190] min: minutes

[0191] ml: milliliters

[0192] mV: millivolt

[0193] psi: pounds per square inch

[0194] PS: The platen rotation speed of the polishing equipment, in rpm (revolutions per minute)

[0195] SF: composition flow rate, ml / min

[0196] wt%: weight percentage (of listed components)

[0197] W:TEOS selectivity: (W removal rate) / (TEOS removal rate)

[0198] HDP: High-density plasma deposited TEOS

[0199] TEOS or HDP Removal Rate: The TEOS or HDP removal rate measured at a given downforce.

[0200] Agglomeration Ratio: Agglomeration Ratio is a descriptor of non-spherical particle shape. It is the quotient of the secondary particle size determined by DLS and the calculated primary particle size, which is derived from the BET surface area as is well known in the art.

[0201] Aggregation ratio = secondary particle size / primary particle size

[0202] Primary particle size = 2727 / specific surface area measured by BET

[0203] Measurement

[0204] The films were measured using a Model 168 ResMap CDE manufactured by Creative Design Engineering, Inc., 20565 Alves Dr., Cupertino, CA, 95014. The ResMap instrument is a four-point probe sheet resistance tool. The film was scanned at 49 points in diameter with 5 mm edge exclusion.

[0205] CMP equipment

[0206] The CMP equipment used was a 200 mm Mirra or 300 mm Reflexion manufactured by Applied Materials, 3050 Bowers Avenue, Santa Clara, California, 95054. An IC1000 pad supplied by DOW, Inc., 451 Bellevue Rd., Newark, DE 19713 was used on platen 1 for blanket and pattern wafer studies.

[0207] Wear in the IK4250UH pad or other pad by conditioning the pad for 18 minutes under 7 lbs of downward force on the conditioner. To qualify the equipment setup and pad wear-in, two tungsten monitors and two TEOS monitors were placed under baseline conditions using a tungsten monitor supplied by Versum Materials Inc. STI2305 composition was used for polishing.

[0208] All polishing data in the following examples were generated on a Mirra polisher using an IC 1010 pad at a polishing down force of 2.5 psi.

[0209] chip

[0210] Polishing experiments were performed using PECVD or LPCVD or HD TEOS wafers. These blanket wafers were purchased from Silicon Valley Microelectronics, 2985 Kifer Rd., Santa Clara, CA 95051.

[0211] Abrasive modification experiment

[0212] Example 1 (Comparative Example)

[0213] Synthesis of elongated silica nanoparticles modified with polyaminoorganosiloxane

[0214] In a 2000 ml four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (911.50 g; 978.49 mmol SiO2; elongated shape, aggregation ratio: 2.86; size of 95.8 nm measured by DLS; pH 10.5) was heated to 70° C. while stirring. While continuing to stir, (3-aminopropyl)dimethoxymethylsilane (1.22 ml; 7.06 mmol), tetraethoxysilane (14.07 ml; 63.51 mmol), and ethanol (140.57 ml; 2410.57 mmol; 2.46 ).

[0215] The volatile organic solvent was exchanged with water by rotary evaporation, and the resulting suspension of polyaminoorganosiloxane-modified elongated silica particles was adjusted to pH 2.5 with HNO 3 and finally concentrated to a solids content of 20 wt %.

[0216] A suspension of colloidally stabilized one-step modified elongated silica nanoparticles of 97.1 nm in size (measured by DLS) was produced.

[0217] Example 2

[0218] In a 2000 ml four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (911.50 g; 978.49 mmol SiO2, elongated shape, aggregation ratio: 2.86; size of 95.8 nm measured by DLS, pH 10.5) was heated to 70° C. while stirring. While continuing to stir, (3-aminopropyl)dimethoxymethylsilane (1.22 ml; 7.06 mmol), tetraethoxysilane (14.07 ml; 63.51 mmol) and ethanol (140.57 ml; 2410.57 mmol; 2.46 ).

[0219] In a subsequent step, a mixture of trimethylmethoxysilane (99%; 0.975 ml; 7.055 mmol;) and ethanol (16.75 ml; 287.18 mmol;) was added over the course of 6 hours while stirring at 70°C and subsequently at room temperature for 12 hours.

[0220] The volatile organic solvent was exchanged with water by rotary evaporation, and the resulting suspension of polyaminoorganosiloxane-modified elongated silica particles was adjusted to pH 2.5 with HNO 3 and finally concentrated to a solids content of 20 wt %.

[0221] A suspension of colloidally stabilized two-step modified elongated silica nanoparticles of 98.1 nm in size (measured by DLS) was produced.

[0222] Example 3

[0223] In a 2000 ml four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (911.50 g; 978.49 mmol SiO2; elongated shape, aggregation ratio: 2.86; size of 95.8 nm measured by DLS; pH 10.5) was heated to 70° C. while stirring. While continuing to stir, (3-aminopropyl)dimethoxymethylsilane (1.22 ml; 7.06 mmol), tetraethoxysilane (14.07 ml; 63.51 mmol), and ethanol (140.57 ml; 2410.57 mmol; 2.46 ).

[0224] In a subsequent step, a mixture of trimethylmethoxysilane (99%; 1.95 ml; 14.11 mmol;) and ethanol (16.75 ml; 287.18 mmol;) was added over the course of 6 hours while stirring at 70°C and subsequently at room temperature for 12 hours.

[0225] The volatile organic solvent was exchanged with water by rotary evaporation, and the resulting suspension of polyaminoorganosiloxane-modified elongated silica particles was adjusted to pH 2.5 with HNO 3 and finally concentrated to a solids content of 20 wt %.

[0226] A suspension of colloidally stabilized two-step modified elongated silica nanoparticles of 99.7 nm in size (measured by DLS) was produced.

[0227] Example 4 (Comparative Example)

[0228] Synthesis of elongated silica nanoparticles modified with polyaminoorganosiloxane

[0229] In a 2000 ml four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (564.97 g; 1664.33 mmol SiO2; elongated shape, aggregation ratio of 2.71; size of 91.6 nm measured by DLS; pH 10.5) was heated to 70° C. while stirring. While continuing to stir, a mixture of 3-aminopropyltriethoxysilane (5.59 ml; 24.00 mmol), tetraethoxysilane (47.87 ml; 216.00 mmol) and ethanol (468.07 ml; 8.03 mol) was added and stirred for 12 hours.

[0230] The volatile organic solvent was exchanged with water by rotary evaporation.The resulting suspension of polyaminoorganosiloxane-modified elongated silica particles was adjusted to pH 2.5 with HNO3 and finally concentrated to a solids content of 20 wt%.

[0231] A suspension of colloidally stable, one-step modified elongated silica nanoparticles of 94.5 nm in size (measured by DLS) was produced.

[0232] Example 5

[0233] In a 2000 ml four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (564.97 g; 1664.33 mmol SiO2; elongated shape, aggregation ratio of 2.71; size of 91.6 nm measured by DLS; pH 10.5) was heated to 70° C. while stirring. While continuing to stir, a mixture of 3-aminopropyltriethoxysilane (5.59 ml; 24.00 mmol), tetraethoxysilane (47.87 ml; 216.00 mmol) and ethanol (468.07 ml; 8.03 mol) was added and stirred for 12 hours.

[0234] In a subsequent step, a mixture of trimethylmethoxysilane (99%; 1.658 ml; 12.00 mmol) and ethanol (16.75 ml; 287.18 mmol) was added over 6 hours while stirring at 70° C. and subsequently at room temperature for 12 hours.

[0235] The volatile organic solvent was exchanged with water by rotary evaporation, and the resulting suspension of polyaminoorganosiloxane-modified elongated silica particles was adjusted to pH 2.5 with HNO 3 and finally concentrated to a solids content of 20 wt %.

[0236] A suspension of colloidally stabilized two-step modified elongated silica nanoparticles of 96.1 nm in size (measured by DLS) was produced.

[0237] Example 6

[0238] In a 2000 ml four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles (564.97 g; 1664.33 mmol SiO2; elongated shape, aggregation ratio of 2.71; size of 91.6 nm measured by DLS; pH 10.5) was heated to 70° C. with stirring. While continuing to stir, a mixture of 3-aminopropyltriethoxysilane (5.59 ml; 24.00 mmol), tetraethoxysilane (47.87 ml; 216.00 mmol) and ethanol (468.07 ml; 8.03 mol) was added and stirred for 12 hours.

[0239] In a subsequent step, a mixture of trimethylmethoxysilane (99%; 1.658 ml; 36.00 mmol) and ethanol (50.25 ml; 861.54 mmol) was added over 12 hours while stirring at 70°C and subsequently at room temperature for 12 hours.

[0240] The volatile organic solvent was exchanged with water by rotary evaporation, and the resulting suspension of polyaminoorganosiloxane-modified elongated silica particles was adjusted to pH 2.5 with HNO 3 and finally concentrated to a solids content of 20 wt %.

[0241] A suspension of colloidally stabilized two-step modified elongated silica nanoparticles of 98.6 nm in size (measured by DLS) was produced.

[0242] Example 7 (Comparative Example)

[0243] Synthesis of elongated silica nanoparticles modified with polyaminoorganosiloxane

[0244] In a 1000 mL four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (482.43 g; 1170 mmol SiO2; elongated shape, aggregation ratio 2.98; size 86.2 nm measured by DLS; pH 4.3) was heated to 70°C with stirring.

[0245] While stirring continuously, the individual reactant streams were added simultaneously to the flask over a period of 1 hour via precision pumps. Just before reaching the flask, the reactant streams were mixed using a T-joint.

[0246] Stream 1 consisted of (3-aminopropyl)dimethoxymethylsilane (5.81 ml; 33.60 mmol) dissolved in 95 ml of methanol. Stream 2 consisted of 65% nitric acid (2.58 ml; 36.96 mmol) dissolved in 98.2 ml of methanol.

[0247] After addition of the reactants, the mixture of the two streams was stirred at 70° C. for 2 hours, then the volatile reaction products were removed by rotary evaporation and the solids content was adjusted to 20% by weight by addition of water.

[0248] A suspension of colloidally stabilized one-step modified elongated silica nanoparticles of 87.5 nm in size (measured by DLS) was produced.

[0249] Example 8

[0250] In a 1000 mL four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (482.43 g; 1170 mmol SiO2; elongated aggregation ratio 2.98; size 86.2 nm measured by DLS; pH 4.3) was heated to 70°C with stirring.

[0251] While stirring continuously, the two reactant streams were added simultaneously to the flask over a period of 1 hour via precision pumps. Just before reaching the flask, the streams were mixed using a T-junction.

[0252] Stream 1 consisted of (3-aminopropyl)dimethoxymethylsilane (5.81 ml; 33.60 mmol) dissolved in 95 ml of methanol. Stream 2 consisted of 65% nitric acid (2.58 ml; 36.96 mmol) dissolved in 98.2 ml of methanol.

[0253] After mixing the two streams, trimethylmethoxysilane (3.47 ml; 25.2 mmol) dissolved in 62.9 ml of methanol was added to the mixture of the two streams over a period of 1.5 hours.

[0254] The final mixture was stirred at 70° C. for a further 12 h, then the volatile reaction products were removed by rotary evaporation and the solids content was adjusted to 20 wt % by addition of water.

[0255] A suspension of colloidally stabilized two-step modified elongated silica nanoparticles of 87.9 nm in size (measured by DLS) was produced.

[0256] Example 9 (Comparative Example)

[0257] In a 1000 mL four-necked flask equipped with a stirrer and a reflux condenser, a suspension of silica nanoparticles in water (482.43 g; 1170 mmol SiO2; elongated aggregation ratio 2.98; size 86.2 nm measured by DLS; pH 10.5) was heated to 70°C with stirring.

[0258] Trimethylmethoxysilane (3.47 ml; 25.2 mmol) dissolved in 62.9 ml of methanol was added to the reaction mixture over 1.5 hours.

[0259] The mixture was stirred at 70°C for an additional 12 hours before the volatile reaction products were removed by rotary evaporation.

[0260] A highly turbid dispersion of agglomerated silica in water is produced which is not colloidally stable and cannot be used in CMP slurry formulations.

[0261] Chemical Mechanical Planarization (CMP) Experiment

[0262] The modified silica nanoparticle suspension obtained above was used to prepare a W-CMP slurry. The slurry contained 0.1 wt% abrasive (PL-2C), 0.01 wt% ferric nitrate (iron(III) nitrate), 0.08 wt% malonic acid, 0.02 wt% 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 2.0 wt% hydrogen peroxide, 0.1 wt% glycine, and water adjusted to a pH of 2.3 with nitric acid.

[0263] The slurries and removal rates are shown in Table 1.

[0264] Table 1

[0265]

[0266] *APDMS: 3-aminopropyldimethoxymethylsilane;

[0267] **APTES: 3-aminopropyltriethoxysilane;

[0268] ***TMMOS: trimethoxysilane.

[0269] As shown in Table 1, the slurry using the two-step modified abrasive grains is very effective in suppressing the TEOS removal rate while maintaining or increasing W removal, thereby improving the W:TEOS RR selectivity.

[0270] The embodiments of the invention described above, including the working examples, are illustrative of the many embodiments of the invention. It is contemplated that many other configurations of the method may be used, and that the materials used in the method may be selected from a variety of materials other than those specifically disclosed.

Claims

1. Colloidally stabilized amphiphilic abrasive particles, wherein the surface of each colloidally stabilized amphiphilic abrasive particle comprises a hydrophilic portion and a hydrophobic portion.

2. The colloidally stabilized amphiphilic abrasive particle of claim 1 , wherein each of the hydrophilic moieties independently comprises at least one selected from the group consisting of: N-containing groups selected from the group consisting of amines and substituted amines, amino groups, ammonium, ammonium groups, and substituted ammonium groups; sulfonium; phosphonium; sulfate; sulfonate; phosphate; hydroxyl; epoxy; carboxyl; ether; polyether; and polyether groups.

3. The colloidally stabilized amphiphilic abrasive particle of any one of claims 1 to 2, wherein each of the hydrophilic moieties independently comprises at least one selected from an amine, an ammonium, and an alkylammonium group, the alkylammonium group comprising an alkyl group having <20 carbon atoms; <10 carbon atoms, or <4 carbon atoms.

4. The colloidally stabilized amphiphilic abrasive particle of claim 1 , wherein each of the hydrophobic moieties independently comprises at least one member selected from the group consisting of an alkyl group having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms; and an aryl group having <20 carbon atoms, <10 carbon atoms, or <8 carbon atoms.

5. The colloidally stabilized amphiphilic abrasive particle according to any one of claims 1 to 4, wherein each of the hydrophobic moieties independently comprises at least one selected from the group consisting of methyl, ethyl, propyl, butyl, phenyl, benzyl, tolyl, and xylyl groups.

6. The colloidally stabilized amphiphilic abrasive particle according to any one of claims 1 to 5, wherein more than one hydrophilic portion and / or more than one hydrophobic portion can be attached to a linking atom selected from the group consisting of Si, Ce, Al, Zr, C, P, and N atoms; wherein the linking atom connects or bonds the hydrophilic portion and / or the hydrophobic portion to the surface of each colloidally stabilized amphiphilic abrasive particle via a covalent bond.

7. The colloidally stabilized amphiphilic abrasive particle according to any one of claims 1 to 6, wherein the hydrophilic portion is a silane having an amino group; and the hydrophobic portion is a trimethylsilyl group; and the colloidally stabilized amphiphilic abrasive particle has a surface that is highly non-polar and inert to silicon oxide.

8. The colloidally stabilized amphiphilic abrasive particle of any one of claims 1 to 7, wherein the ratio of hydrophilic portion to hydrophobic portion ranges from 1.00:0.01 to 1.00:10.00, 1.00:0.25 to 1.00:5.00, 1.00:0.30 to 1.00:3.00, 1.00:0.40 to 1.00:2.50, or 1.00:0.50 to 1.00:2.

00.

9. The colloidally stabilized amphiphilic abrasive particle according to any one of claims 1 to 8, wherein the surface of each of the colloidally stabilized amphiphilic abrasive particles is a covalently bonded polymer cross-linked shell.

10. The colloidally stabilized amphiphilic abrasive particle according to any one of claims 1 to 9, wherein the surface of each of the colloidally stabilized amphiphilic abrasive particles is a covalently bonded polyorganosiloxane crosslinked shell.

11. A method for preparing colloidally stabilized amphiphilic abrasive particles, comprising: a. providing a base abrasive particle having a reactive M-OH group on its surface, and the base abrasive particle is dispersed in a solvent; b. modifying the surface of the base abrasive particles with a first step surface modifier having at least one hydrophilic group and at least one first reactive group capable of forming a covalent bond with the reactive M-OH group to obtain a step-modified abrasive particle; c. modifying the surface of the one-step modified abrasive particle with a second-step surface modifier having at least one hydrophobic group and at least one second reactive group capable of forming a covalent bond with a reactive X-OH group on the surface of the one-step modified abrasive particle to obtain the amphiphilic abrasive particle; in M in the reactive M-OH group is selected from Si, Ce, Al, Zr, their hybrids and / or mixtures; X in the reactive X-OH group is selected from Si, Ce, Al, Zr, C, P, N, hybrids and / or mixtures thereof; and The solvent is selected from water, alcohol, preferably ethanol, ketone, ester, ether, glycol and a combination thereof; preferably a combination of water and alcohol.

12. The method of claim 11 , wherein the at least one first reactive group or the at least one second reactive group is independently selected from silicon alkoxides, silicon halides (preferably chlorides), oximes, acetates, silicon hydroxides, and combinations thereof; preferably silicon methoxides and silicon ethoxides.

13. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11-12, wherein the first step surface modifier is selected from silanes having the at least one hydrophilic group, and the second step surface modifier is selected from silanes having the at least one hydrophobic group.

14. The method of claim 11 , wherein the at least one hydrophilic group comprises at least one selected from the group consisting of an amine, amino, ammonium, ammonium and substituted ammonium group containing N; a sulfonium group; a phosphonium group; a sulfate group; a sulfonate group; a phosphate group; a hydroxyl group; an epoxy group; a carboxyl group; an ether; a polyether group; or a polyether group; preferably selected from the group consisting of an amine, amino, ammonium and alkylammonium group containing N, the substituted ammonium group including but not limited to an alkylammonium group containing an alkyl group having <20 carbon atoms, <10 carbon atoms or <4 carbon atoms.

15. according to the method for preparing colloidally stable amphiphilic abrasive grain described in any one of claim 11-14, wherein said at least one hydrophilic group comprises at least one selected from amine, ammonium and alkylammonium group, and described alkylammonium group comprises alkyl group with<20 carbon atoms,<10 carbon atoms or<4 carbon atoms.

16. according to the method for preparing the colloid-stabilized amphiphilic abrasive grain described in any one of claim 11-15, wherein said at least one hydrophobic group comprises and is selected from the alkyl group having<20 carbon atoms,<10 carbon atoms or<4 carbon atoms; With at least one of the aryl group having<20 carbon atoms,<10 carbon atoms or<8 carbon atoms.

17. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 16, wherein the at least one hydrophobic group consists of at least one selected from the group consisting of methyl, ethyl, propyl, butyl, phenyl, benzyl, tolyl and xylyl.

18. A method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 17, wherein the second step surface modifier comprises a silane having at least two, preferably at least three, hydrophobic groups, the hydrophobic groups comprising an alkyl group having <20 carbon atoms, <10 carbon atoms, or <4 carbon atoms; or an aryl group having <20 carbon atoms, <10 carbon atoms, or <8 carbon atoms.

19. A method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 18, wherein the second-step surface modifier does not carry a functional group on the hydrophobic group of the alkyl or aryl group.

20. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 19, wherein the solvent is selected from the group consisting of water, ethanol, acetone, ethyl ether, propylene glycol dimethyl ether, propylene glycol monoacetate, isopropyl alcohol, n-propyl alcohol, propylene glycol monomethyl ether, and combinations thereof; preferably a combination of water and ethanol.

21. A method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 20, wherein the total amount of the first step surface modifier and the second step surface modifier is in the range of 0.01-1.0 mmol / g (abrasive mass calculated as dry matter), 0.025-0.8 mmol / g, 0.05-0.5 mmol / g or 0.1-0.4 mmol / g.

22. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 21, wherein the base abrasive particles are selected from the group consisting of colloidal silica, fumed silica, alumina, ceria, and combinations thereof.

23. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 22, wherein the first step surface modifier is selected from amino-polyether silanes and betaine-type silanes.

24. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 23, wherein the first step surface modifier is selected from 3-aminopropyl derivatives of ethoxysilane or methoxysilane; and combinations thereof.

25. The method of making colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 24, wherein the first step surface modifier is 3-aminopropylmethyldimethoxysilane.

26. A method of preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 25, wherein the first step surface modifiers are capable of reacting among themselves to form a covalently bonded polymeric crosslinked shell around the base abrasive particles.

27. A method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 26, wherein the second step surface modifier is selected from the group consisting of trimethylmethoxysilane, trimethylethoxysilane, dimethylphenylmethoxysilane, diphenylsilanediol, diphenyldimethoxysilane, methylphenyldimethoxysilane, dimethyldimethoxysilane, hexamethyldisilazane, hexamethyldisiloxane, dimethylethylmethoxysilane, dimethyloctylmethoxysilane, dimethyloctadecylchlorosilane, dimethylhexadecylmethoxysilane, dimethyl(methylphenyl)methoxysilane, potassium trimethylsilanol, triethylmethoxysilane, and combinations thereof.

28. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 27, wherein the second-step surface modifier is selected from the group consisting of trimethylmethoxysilane, trimethylethoxysilane, and combinations thereof.

29. The method of making colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 28, wherein the first step surface modifier is 3-aminopropylmethyldimethoxysilane; and the second step surface modifier is selected from the group consisting of trimethylmethoxysilane, trimethylethoxysilane, and combinations thereof.

30. A method of making colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 29, wherein the ratio of the first step modifier to reactants is in the range of 9.9:1 to 0.1:9.9, preferably 9:1 to 1:

9.

31. A method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 30, wherein the first step surface modifier is used in combination with a reactant selected from the group consisting of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and combinations thereof; and the ratio of the first step modifier to the reactants is from 9.9:1 to 0.1:9.9; preferably from 9:1 to 1:

9.

32. The method for preparing colloidally stabilized amphiphilic abrasive particles according to any one of claims 11 to 31, further comprising, after step c, step d: maintaining water as the only dispersion medium after the second step of surface modification.

33. Colloidally stabilized amphiphilic abrasive particles prepared according to any one of claims 11 to 32.

34. A chemical mechanical polishing (CMP) composition comprising: Colloidally stabilized amphiphilic abrasive particles according to any one of claims 1 to 10 or claim 33; and solvents; Optionally comprising at least one of the following: organic and inorganic salts, as colloidal stabilizers; catalysts, including but not limited to fluoride ions, metal salts, or metal alkoxides, such as titanium isopropoxide; Acid / base pH buffers; biocides; oxidants; catalyst; and corrosion inhibitors; in The solvent is selected from water; a water-soluble solvent selected from alcohols, ethers and ketones; and combinations thereof; and The CMP composition has a pH of 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, or 2 to 3.

35. A chemical mechanical polishing (CMP) method comprising: providing a substrate having at least one surface comprising tungsten; A chemical mechanical polishing (CMP) composition is provided, comprising: Colloidally stabilized amphiphilic abrasive particles according to any one of claims 1 to 10 or claim 33; and Water-soluble solvents; wherein the CMP composition has a pH of 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, or 2 to 3; contacting a surface of a semiconductor substrate with a polishing pad and the chemical mechanical polishing composition; and The at least one surface comprising tungsten is polished.

36. The chemical mechanical polishing (CMP) method of claim 35, wherein the surface of the semiconductor substrate further comprises a silicon dioxide film; and a removal selectivity of W:SiO2 is greater than 80, 100, 150, or 200.

37. A chemical mechanical polishing (CMP) system comprising: polishing pads; a substrate having at least one surface comprising tungsten; A chemical mechanical polishing (CMP) composition comprising: Colloidally stabilized amphiphilic abrasive particles according to any one of claims 1 to 10 or claim 33; and Water-soluble solvents; wherein the CMP composition has a pH of 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, or 2 to 3; The surface of the semiconductor substrate is in contact with the polishing pad and the chemical mechanical polishing composition, so that tungsten can be polished.

38. The chemical mechanical polishing (CMP) system of claim 37, wherein the surface of the semiconductor substrate further comprises a silicon dioxide film; and a removal selectivity of W:SiO2 is greater than 80, 100, 150, or 200.

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