Compositions and methods for polishing of transition metals

Abstract

This invention provides compositions suitable for polishing transition metal-containing surfaces commonly found on microelectronic devices. In one embodiment, the invention provides a composition comprising: a liquid carrier; titanium dioxide abrasive particles, wherein the particles are at least partially coated with alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor. The compositions of this invention are advantageously used for polishing microelectronic device substrates having transition metal-containing surfaces. In some embodiments, these surfaces are selected from molybdenum-containing and ruthenium-containing films, exhibiting significantly improved selectivity relative to thermal oxides.

Description

[Technical Field]

[0001] This invention generally relates to the field of microelectronic device manufacturing. More specifically, this invention relates to compositions and methods for chemical mechanical polishing of transition metals such as molybdenum, tungsten, cobalt, copper and ruthenium. [Previous Technology]

[0002] Microelectronic device wafers are used to form integrated circuits. A microelectronic device wafer contains a substrate (such as silicon), regions of which are patterned to deposit different materials with insulating, conductive, or semi-conductive properties. To achieve proper patterning, excess material used to form layers on the substrate must be removed. Furthermore, to manufacture functional and reliable circuits, it is generally important to prepare a flat or planar microelectronic wafer surface before subsequent processing. Therefore, it is necessary to planarize and / or polish certain surfaces of the microelectronic device wafer. Additionally, for optical devices, it may be necessary to smooth these surfaces for light transmission or to remove subsurface damage.

[0003] Chemical mechanical polishing or planarization ("CMP") is a process that removes material from the surface of a microelectronic device wafer and planarizes and polishes the surface by combining physical processes (such as abrasion) and chemical processes (such as oxidation or chelation). In its most basic form, CMP involves applying a slurry (such as a solution of abrasives and active chemicals) to a polishing pad to polish the surface of the microelectronic device wafer to achieve removal, planarization, and polishing. It is generally not desirable for the removal or polishing process to involve purely physical or purely chemical actions, but rather a synergistic combination of both to achieve rapid and uniform removal. In the fabrication of integrated circuits, CMP slurries should also be able to preferentially remove films including composite layers of metals and other materials, thereby producing highly flat surfaces for subsequent photolithography, patterning, etching, and thin-film processing. In conventional CMP operations, a substrate carrier or polishing head is mounted on a carrier assembly and placed in contact with a polishing pad within the CMP apparatus. The carrier assembly provides controlled pressure to the substrate, pressing the substrate onto the polishing pad. The pad is then moved relative to the substrate.

[0004] Molybdenum metal is used in interconnects, photomasks, etc., in microelectronic devices. Generally, molybdenum is present in excess on the device, and then the excess molybdenum needs to be removed by polishing or grinding. When using silica abrasive compositions, molybdenum polishing generally exhibits a low removal rate. When using oxidants (such as hydrogen peroxide), high corrosion rates are often encountered.

[0005] Ruthenium is being considered as a replacement for Ta / TaN as a barrier material in copper interconnects, as a bottom electrode material in metal-insulator-metal capacitors, and as a next-generation pad and conductive metal. Ruthenium can be polished using abrasives and oxidants; unfortunately, some of these compositions raise safety and toxicity concerns due to reaction products from this polishing process. Furthermore, ruthenium polishing is typically accompanied by low removal rates and high etching rates using conventional (colloidal) silica and iodate (i.e., oxidant) chemicals. Additionally, this method suffers from severe pad staining, especially under neutral to alkaline pH conditions, and poor reproducibility. In this regard, pad staining is believed to be a byproduct of ruthenium oxidation, which potentially produces insoluble species that can ultimately lead to undesirable scratches on the ruthenium surface.

[0006] Therefore, there is still a need for novel and improved compositions and methods for polishing molybdenum and ruthenium without such difficulties. [Summary of the Invention]

[0007] In summary, the present invention provides compositions suitable for polishing transition metal-containing surfaces commonly found on microelectronic devices. In one embodiment, the present invention provides a composition comprising: a liquid carrier; titanium dioxide abrasive particles, wherein the particles are at least partially coated with alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor.

[0008] In the method of the present invention, the compositions are advantageously used to polish microelectronic device substrates having transition metal surfaces thereon. In some embodiments, such surfaces are selected from molybdenum-containing and ruthenium-containing films.

Implementation Method

[0012] As used in this specification and the accompanying claims, unless expressly indicated otherwise, the singular forms “a,” “an,” and “the” include a plurality of indicators. As used in this specification and the accompanying claims, unless expressly indicated otherwise, the term “or” is used generally in the sense that it includes “and / or.”

[0013] The term "about" generally refers to a series of numerical values ​​that are considered equivalent to the referenced value (e.g., having the same function or result). In many cases, the term "about" may include numerical values ​​rounded to the nearest significant number.

[0014] The range of values ​​represented by endpoints includes all values ​​covered within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4 and 5).

[0015] The compositions of the present invention are suitable for use in CMP polishing compositions (i.e., slurries) containing transition metal materials. In one embodiment, such metals include ruthenium, rhodium, palladium, osmium, iridium, platinum, gold, silver, copper, and rhenium. In another embodiment, such metals include tungsten, cobalt, and copper, and oxides and nitrides of such metals. In yet another embodiment, such metals include ruthenium and molybdenum. Thus, the present invention provides a composition in a first embodiment comprising: a liquid carrier; titanium dioxide abrasive particles, wherein such particles are at least partially coated with alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein such coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor.

[0016] In this invention, the coated titanium dioxide (TiO2) particles are widely commercially available. These coated titanium dioxide particles generally have an average diameter of about 50 to about 250 nm, about 100 to about 250 nm, about 50 nm to about 150 nm, or about 20 nm to about 50 nm. Coating these titanium dioxide particles with amorphous silica or alumina can be accomplished by known methods. See, for example, "Dense silica coating of titania nanoparticles by seeded polymerization technique," Ahmed Mohamed El-Toni, Shu Yin, and Tsugio Sato, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 274, Nos. 1-3, February 15, 2006, pp. 229-233. Coating titanium dioxide with alumina (Al2O3) can be accomplished by the following gas-phase deposition methods: hydrolysis or decomposition of volatile substances; addition of oxides, hydroxides, or substances that can be adsorbed onto the surface during pigment grinding, resulting in a partial coating on the pigment surface; or precipitation of the coating from an aqueous solution onto suspended TiO2 particles.

[0017] In one embodiment, the titanium dioxide abrasive particles are in rutile form. Generally, component b above (i.e., the coated titanium dioxide particles) mainly comprises titanium dioxide (together with the alumina or amorphous silica coating); however, in addition to titanium dioxide, small amounts of dopants or materials may also be present in the titanium dioxide abrasive particles, such as about 5% by weight or less, about 2% by weight or less, or about 1% by weight or less.

[0018] As described above, the compositions of the present invention comprise at least one organic corrosion inhibitor. Essentially, such organic corrosion inhibitors belong to the general category of surfactants. As used herein, the term "surfactant" refers to an organic compound that reduces the surface tension (or interfacial tension) between two liquids or between a liquid and a solid, and is generally an organic amphiphilic compound containing both a hydrophobic group (e.g., a hydrocarbon (e.g., an alkyl "tail") and a hydrophilic group. In one embodiment, such surfactants or metal corrosion inhibitors are cationic surfactants. Cationic surfactants are essentially surface-active molecules having at least one positively charged moiety. In one embodiment, the cationic surfactant is selected from C6-C18 ammonium halides. "C6-C18" modifiers refer to the number of carbon atoms in the surfactant and may include aliphatic and aromatic moieties. In another embodiment, the cationic surfactant is selected from C12-C18 ammonium halides.

[0019] Exemplary cationic surfactants (corrosion inhibitors) include, but are not limited to, cetyltrimethylammonium bromide (CTAB) (also known as hexadecyltrimethylammonium bromide), hexadecyltrimethylammonium chloride (CTAC), heptadecanylfluorooctane sulfonic acid, tetraethylammonium halide, stearyltrimethylammonium chloride, 4-(4-diethylaminophenylazo)-1-(4-nitrobenzyl)pyridine bromide, cetylpyridinium chloride monohydrate, dimethylammonium chloride, dimethylammonium bromide, benzyldimethylammonium chloride, benzyldimethylammonium chloride, benzyldimethyl dodecylammonium chloride, benzyldimethylhexadecylammonium chloride, hexadecyltrimethylammonium bromide, dimethyl dioctadecylammonium chloride, dodecyltrimethylammonium chloride, didodecyldimethylammonium bromide, di(hydrogenated tallow)dimethylammonium chloride, tetraheptylammonium bromide, tetra(decyl)ammonium bromide and hydroxyphenylacetyl bromide, dimethyl dioctadecylammonium chloride, dimethyl dihexadecylammonium bromide and di(hydrogenated tallow)dimethylammonium chloride. In one embodiment, the corrosion inhibitor / surfactant is selected from phthalic anhydride ammonium chloride and phthalic anhydride ammonium bromide.

[0020] These corrosion inhibitors / surfactants are typically present in an amount of about 0.0001 to about 5% by weight (based on the total weight of the composition), and are found to be necessary by empirical observation.

[0021] In the compositions of the present invention, the relative amount of coated titanium dioxide particles can be adjusted as needed based on the total weight of the composition for polishing specific transition metal surfaces. In some embodiments, the coated titanium dioxide particles are present in an amount of about 0.001 to about 5% by weight, or about 0.1 to about 1% by weight (based on the total weight of the composition). Any suitable amount of abrasive may be present in the polishing composition, depending on the surface being polished and other conditions used. In some embodiments, the abrasive is present in the polishing composition at a concentration of about 0.0005 wt.% or more, such as about 0.001 wt.% or more, about 0.0025 wt.% or more, about 0.005 wt.% or more, about 0.01 wt.% or more, about 0.025 wt.% or more, or about 0.05 wt.% or more. More typically, the abrasive is present in the polishing composition at a concentration of about 0.001 wt.% or more, such as about 0.0025 wt.% or more, about 0.005 wt.% or more, about 0.01 wt.% or more, about 0.025 wt.% or more, or about 0.05 wt.% or more. Alternatively, the abrasive is present in the polishing composition at a concentration of about 30 wt.% or less, such as about 20 wt.% or less, about 10 wt.% or less, about 5 wt.% or less, about 1 wt.% or less, about 0.5 wt.% or less, about 0.1 wt.% or less, or about 0.05 wt.% or less. More typically, the abrasive is present in the polishing composition at a concentration of about 1 wt.% or less, such as about 0.5 wt.% or less, about 0.1 wt.% or less, or about 0.05 wt.% or less. Therefore, the abrasive may be present in the polishing composition in amounts defined by any two of the above endpoints.For example, the abrasive can be from about 0.0005 wt.% to about 10 wt.%, such as about 0.001 wt.% to about 10 wt.%, about 0.001 wt.% to about 1 wt.%, about 0.001 wt.% to about 0.5 wt.%, about 0.001 wt.% to about 0.1 wt.%, about 0.001 wt.% to about 0.05 wt.%, about 0.005 wt.% to about 10 wt.%, about 0.005 wt.% to about 1 wt.%, about 0.005 wt.% to about 0.5 wt.%, about 0.005 wt.% to about 0.1 wt.%, about 0.005 wt.% to about 0.05 wt.%, about 0.01 wt.% to about 10 wt.%, about 0.01 wt.% The abrasive is present in the polishing composition at a concentration of about 0.001 wt.% to about 1 wt.%, about 0.01 wt.% to about 0.5 wt.%, about 0.01 wt.% to about 0.1 wt.%, about 0.01 wt.% to about 0.05 wt.%, about 0.05 wt.% to about 10 wt.%, about 0.05 wt.% to about 1 wt.%, about 0.05 wt.% to about 0.5 wt.%, about 0.05 wt.% to about 0.1 wt.%, or about 0.05 wt.% to about 0.05 wt.%. In some embodiments, the abrasive is present in the polishing composition at a concentration of about 0.001 wt.% to about 1 wt.%.

[0022] In another embodiment, the composition of the present invention further comprises at least one oxidizing agent. As used herein, the term "oxidizing agent" refers to any chemical substance other than ambient air capable of oxidizing ruthenium to an oxidation state of +4 or higher. Exemplary lists of such oxidizing agents include, but are not limited to, peroxides (e.g., H₂O₂), periodic acid, oxone, bromate, bromate, hypobromite, chlorate, chlorite, hypochlorite, perchlorate, iodate, hypoiodide, periodate, cerium(IV) salts, permanganate, silver(III) salts, peracetic acid, organohalooxy compounds, monoperoxysulfate, monoperoxysulfite, monoperoxythiosulfate, monoperoxyphosphate, monoperoxypyrophosphate, and monoperoxyhypophosphate. Other oxidizing agents include hydrogen peroxide; other peroxides, such as salts and acids containing anions of peroxymonosulfate, perborate, perchlorate, periodate, persulfate, permanganate, and peracetic acid; and amine-N-oxides. Other examples include FeCl3, FeF3, Fe(NO3)3, Sr(NO3)2, COF3, MnF3, ozone, 2KHSO5•KHSO4•K7SO4, iodic acid, vanadium oxide (V), vanadium oxide (IV, V), ammonium vanadate, and polyatomic ammonium salts (e.g., ammonium persulfate, ammonium chlorite (NH4ClO2), ammonium perchlorate (NH4ClO3), ammonium iodate (NH4IO3), ammonium nitrate (NH4NO3), and ammonium perborate (NH4NO3). Ammonium perchlorate (NH4ClO4), ammonium periodate (NH4IO4), ammonium persulfate ((NH4)2S2O8), ammonium hypochlorite (NH4ClO)), ammonium tungstate ((NH4)10H2(W2O7)), polyatomic sodium salts (e.g., sodium persulfate (Na2S2O8), sodium hypochlorite (NaClO), sodium perborate), polyatomic potassium salts (e.g., potassium iodate (KIO3), potassium permanganate (KMnO4), potassium persulfate, nitric acid (HNO3) 3) Potassium persulfate (K₂S₂O₈), potassium hypochlorite (KClO), polyatomic tetramethylammonium salts (e.g., tetramethylammonium chlorite (N(CH₃)₄)ClO₂), tetramethylammonium chlorate (N(CH₃)₄ClO₃), tetramethylammonium iodate (N(CH₃)₄)IO₃, tetramethylammonium perborate (N(CH₃)₄)BO₃, tetramethylammonium perchlorate (N(CH₃)₄)ClO₄, tetramethylammonium periodate (N(CH₃)₄)ClO₄, ... 4) IO4), tetramethylammonium persulfate ((N(CH3)4)S2O8)), polyatomic tetrabutylammonium salts (e.g., tetrabutylammonium peroxymonosulfate), peroxymonosulfate, ferric nitrate (Fe(NO3)3), hydrogen peroxide urea ((CO(NH2)2)H2O2), peracetic acid (CH3(CO)OOH), 1,4-benzoquinone, formone, dimethyl-1,4-benzoquinone, chloroquinone, alloxan, 4-methylmorpholine N-oxide, trimethylamine N-oxide and combinations thereof.Other examples of oxidants include perbromic acid, trifluoroperacetic acid tellurate, m-chloroperoxybenzoic acid, tert-butyl hydroperoxide, benzoyl peroxide, potassium persulfate (e.g., Oxone® DuPont), methyl ethyl ketone peroxide, acetone peroxide, ethyl hydroperoxide, and cumene hydroperoxide.

[0023] In one embodiment, the amount of oxidant based on the total weight of the composition is in the range of about 0.001% by weight to about 5% by weight, and in another embodiment it is in the range of about 0.001% by weight to about 2% by weight.

[0024] In some embodiments, the peroxide oxidant is used in conjunction with a Fe(II) or Fe(III) source (such as Fe(NO3)3 in the Fenton reaction), which generates hydroxyl radicals in situ as oxidants in the Fenton reaction.

[0025] The compositions of the present invention may further include pH stabilizers. Both organic and inorganic pH stabilizers may be used. Examples of inorganic pH stabilizers include phosphates, phthalates, bicarbonates, and silicates. Examples of organic pH stabilizers include amines, glycine, and N-cyclohexyl-2-aminoethanesulfonic acid. In some embodiments, the compositions of the present invention will have a pH of about 2 to about 5. For a given composition, if necessary, pH adjusters such as acetic acid, nitric acid, sulfuric acid, hydrochloric acid, and phosphoric acid may be used, or, if necessary, pH adjusters such as KOH, tetramethylammonium hydroxide (TMAH), tetrabutylammonium hydroxide (TBAH), etc., may be used to make the given composition more alkaline.

[0026] The composition may further include a biocidal agent, such as a fungicide. Examples of fungicides include tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, alkylbenzyldimethylammonium chloride and alkylbenzyldimethylammonium hydroxide, 3,5-dimethyltetrahydro-1,3,5,2H-thiadiazine-2-thione, 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, sodium chlorite and sodium hypochlorite.

[0027] As described above, the composition includes a liquid carrier. The liquid carrier includes water (e.g., deionized water) and, if necessary, further includes one or more water-miscible organic solvents. Examples of usable organic solvents include alcohols such as isopropanol, ethanol, 1-propanol, methanol, 1-hexanol, and the like; aldehydes such as acetaldehyde and the like; ketones such as acetone, diacetone alcohol, methyl ethyl ketone, and the like; esters such as ethyl formate, propyl formate, ethyl acetate, methyl acetate, methyl lactate, butyl lactate, ethyl lactate, and the like; ethers including sulfoxides such as dimethyl sulfoxide (DMSO), tetrahydrofuran, dioxane, dimethyl diethylene glycol, and the like; amides such as N,N-dimethylmethoxyamine, dimethylimidazolium, N-methylpyrrolidone, and the like; polyols and their derivatives such as ethylene glycol, glycerol, diethylene glycol, diethylene glycol monomethyl ether, and the like; and nitrogen-containing organic compounds such as acetonitrile, pentylamine, isopropylamine, imidazole, dimethylamine, and the like. In one embodiment, the liquid carrier is only water, i.e., no organic solvent is present.

[0028] In some embodiments, the composition of the present invention comprises or is substantially composed of components a. and b. above and optional components stated herein. In some embodiments, the composition is substantially free of oxidants. As used herein, the phrase "substantially free of oxidants" means a composition comprising less than about 1 ppm of oxidants, such as less than about 100 ppb, less than about 10 ppb, less than about 1 ppb, less than about 100 ppt, less than about 10 ppt, or less than about 1 ppt. In some embodiments, the polishing composition is free of oxidants (i.e., below the detection level).

[0029] The polishing process can be performed at a temperature of about 15°C to about 100°C. Higher temperatures are expected to increase the polishing rate of molybdenum or ruthenium. In one embodiment, the temperature range is about 25°C to about 65°C. One way to achieve higher temperatures is to preheat the slurry before it is supplied to the CMP apparatus.

[0030] Regarding the polishing pad, any type of polymer-based polishing pad can generally be used. Examples of polishing pads are based on polyurethane pads and chamois pads. The pad thickness can vary from 0.1 mm to 25 mm. The hardness of such chamois pads can vary from Asker C hardness 5 to Asker C hardness 95. The compressibility of the chamois pad can be from 0.1% to 40%. The pore size of the porous chamois pad can vary from 2 micrometers to 100 micrometers, wherein in one embodiment the size is in the range of 20 to 60 micrometers. The porous pad layer can have a backing layer of polyethylene terephthalate (PET) or foam or nonwoven material with a thickness between 30 micrometers and 25 mm.

[0031] In addition to porous pads, polyurethane pads can also be used. Examples of polyurethane-based pads include the D-100 pad from Cabot Microelectronics, and the IC and Suba Series from Dow Electronics Materials. These pads have a Shore D value ranging from 5 to 99. The porosity of these pads can vary from 0.1% to 40%. It should be noted that any other type of polymeric material can generally be used with this slurry. Besides using these porous pads, metal pads (such as cast iron, copper, tin), granite, or resin surfaces can also be used as pads.

[0032] Suitable apparatus for chemical mechanical polishing is commercially available. The method of the present invention generally involves mixing a slurry composition comprising the above-described components, placing the dielectric substrate to be polished in a CMP apparatus having a rotating pad, and then performing chemical mechanical polishing using the slurry composition of the present invention. In this polishing method, at least some of the dielectric substrate surface is removed or abraded, thereby providing a properly polished dielectric substrate.

[0033] Therefore, in another embodiment, the present invention provides a method for chemically mechanically polishing a substrate comprising a surface including at least one transition metal, the method comprising: contacting the substrate with a composition comprising: a liquid carrier; titanium dioxide abrasive particles, wherein the particles are at least partially coated with alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor; moving the composition relative to the substrate; and abrading the substrate to remove a portion of the surface including the at least one transition metal.

[0034] Advantageously, when compared with conventional slurries, the compositions and methods of the present invention exhibit significantly improved removal rates, up to or greater than about 200% in some embodiments. In addition, in some embodiments, the compositions and methods of the present invention exhibit a molybdenum to thermal oxide selectivity of about 100:1 for polishing molybdenum-containing films and about 12:1 for ruthenium-containing films.

[0035] The compositions of the present invention can be readily formulated by simply adding the individual components and mixing to a homogeneous state. These compositions can be readily formulated as single-serving formulations or as multi-part formulations to be mixed before or after use. The concentrations of the individual components can vary widely within specific multiples of the composition, i.e., becoming more diluted or more concentrated, and it should be understood that the compositions described herein may vary and may comprise, consist of, or substantially consist of any combination of components consistent with the present invention.

[0036] Therefore, in another embodiment, the present invention provides a kit comprising components selected from a., b. and c. and any optional components as described above in one or more containers for assembly in use.

[0037] Example

[0038] Abbreviations: DL = Detection Limit; CMP = Chemical Mechanical Planarization or Polishing; DIW = Deionized Water; SER = Static Etching Rate; CI = Corrosion Inhibitor (listed in quantities).

[0039] Partial A-Molybdenum Polishing

[0040] In this section A, all concentrations are expressed as a weight percentage unless otherwise indicated. Water is added to make the composition 100% by weight. Furthermore, CMP experiments are performed using the procedures and experimental conditions given below. The data provided in the following examples are obtained by polishing 1.75" x 1.75" specimens cut from a blanket-coated molybdenum wafer. The thickness of these molybdenum films, measured using a profilometer, is 5000 Å. This thickness is confirmed upon receipt using a four-point resistance probe.

[0041] Various abrasives, including colloidal silica, are studied, which are considered conventional abrasives for polishing molybdenum surfaces. These slurries, when used on demand (PoU), are prepared by diluting a slurry with a higher solids load. An appropriate weight of the original slurry is mixed with deionized water (DIW) to achieve the desired solids load. For example, 10.6 g of silica slurry with an initial solids load of 47% by weight is stirred in 89.4 g of DIW to achieve a final particle content of 5% by weight. The operating pH is varied according to the studies mentioned in the following examples. An aqueous solution of nitric acid and potassium hydroxide is used as a pH adjuster.

[0042] The CMP tool used for this polishing process was a Buehler Automet 250 with a platform size of 12". The rotational speed was set to 150 RPM at the base and 30 RPM at the head. Throughout the study, the peristaltic slurry metering pump was set to dispense the polishing slurry at 30 ml / min. Except for testing the effect of pad variation on the removal rate, all processes used Cabot D100 pads with concentric grooves. The polishing duration was set to 60 seconds. The pad temperature mentioned anywhere in this document was measured using an IR thermometer during this polishing process.

[0043] The change in film thickness caused by polishing was determined by measuring the film thickness before and after polishing using a four-point resistance probe. The polishing non-uniformity observed from the change in film thickness of the polished samples is due to the non-uniform pressure distribution from the Buehler polishing machine. To address this non-uniformity, the removal rate was determined based on the film weight lost during polishing. Example 1 (Samples A to F)

[0044] Mo specimens were polished using slurries A through F at an operating pH of 1.5 and a pressure of 4 psi. Two different types of abrasives were used: silica and titanium dioxide. All abrasives were from different suppliers. These are “single-abrasive” slurries, meaning that no oxidizing chemicals were introduced into these formulations. A pressure of 4 psi was used throughout these processes. The solids loading and corresponding removal rates for each slurry are listed in Table 1. It is evident from the values ​​in the table that the titanium dioxide-based slurries produced the highest removal rates in all polishing processes in this group. The higher rate of slurry E, containing 410 nm APS titanium dioxide particles, can be attributed to its larger particle size. However, the comparable rates observed by polishing in the presence of slurries F and G, containing 200 nm APS titanium dioxide particles, are surprising. This higher removal rate is attributed to the surface modification of the titanium dioxide particles in these slurries. The novelty of this surface modification lies in the inorganic coating of transition metal oxides on the surface. This surface functionalization imparts catalytic activity to the titanium dioxide particles, which act as heterogeneous catalytic centers upon contact with the Mo surface. When the Mo surface is polished using a slurry containing these particles, this behavior mimics the CMP effect. This effect is sufficient to maintain the removal rate, and even to maintain a lower solids loading as low as 1%. Table 1: Removal rate data for abrasive slurries alone at operating pH 1.5. Slurry preparation slurry abrasive Particle size (nm) Solid load (%) Average removal rate (Å / min) Abrasives, DIW, pH adjuster A Silicon (Nalco 2320, Nalco) 135 5 110 B Silicon (PL-3, Fuso) 75 twenty three 256 C Silica (Nalco 13573, Nalco) 40 27 192 D Silicon (PL-3, Fuso) 35 20 130 E Uncoated titanium dioxide (R900, Chemours) 410 5 946 F Titanium dioxide coated with alumina 200 5 943 G Titanium dioxide coated with alumina 200 1 872 Example 2

[0045] The Mo specimens were further polished using a "single abrasive" slurry containing the unique coated titanium dioxide particles described in Example 1, with the time being a function of the operating pH. The operating pH varied between 1.5 and 13, maintaining a 5% solids load and a pressure of 4 psi. Table 2 shows the Mo removal rate corresponding to each operating pH. The Mo removal rate is clearly highly dependent on the operating pH, with the highest removal rate observed in highly acidic slurries. The presence of titanium dioxide abrasive has a more significant effect on pH compared to silica abrasives, as it exhibits a significantly higher removal rate. The static etching rate (SER) of Mo at this pH is below the detection limit. Table 2: Removal rate data of single abrasive slurries at different operating pH Slurry preparation pH Average removal rate (Å / min) Slurry F (same as in Example 1) 1.5 943 2 673 3 362 4 335 9.5 398 13 170 Example 3

[0046] The Mo specimens were polished at a constant operating pH of 1.5 in the presence of slurry F. The performance of the slurry with different hardness values ​​was investigated on different polishing pads. Table 2 shows the removal rates and individual hardness values ​​associated with each pad. Hardness values ​​were measured on the Shore D scale using a hardness tester purchased from Electromatic Equipment Co. Inc. Softer pads (pads with lower hardness) exhibited higher removal rates, which is intuitively apparent because the softer pad corresponds to a larger contact area between the pad and the Mo surface. Table 3: Effect of Pad Variation on Mo Removal Rate Slurry preparation pad Shore D hardness Average removal rate (Å / min) Slurry F* at pH=1.5 D100 50 572 FPK 45 520 13M 40 383 ZAN100 g 34 698 SUBA800 15 627 Slurry F and slurry G are made from the same particles, but with different solid loadings at the same pH of the composition: 5% by weight and 1% by weight, respectively. Example 4

[0047] Slurry G was further modified by adding an oxidant to study the increase in removal rate due to the oxidative chemical reaction between Mo and the oxidant. Hydrogen peroxide was added as an oxidant at a concentration of 0.1%. A 100% increase was observed after adding the oxidant. However, the SER was significantly higher than that of the "abrasive alone" formulation. Various corrosion inhibitors (CI 1 to 8, dodecyltrimethylammonium bromide (1), glycine (2), benzotriazole (3), imidazoline oleate (4), dialkyl sulfonate (5), ammonium lauryl sulfate (6), phenylenediamine chloride (7), benzoxonine chloride (8)). The room temperature SER data of the operating pH in the presence of these inhibitors and a 0.1% oxidant concentration are shown in Table 4. The two inhibitors CI-7 and CI-8 showed the greatest effectiveness when the SER value was below the detection limit. Table 4: SER and RR data in the presence of oxidant and corrosion inhibitor. slurry Oxidizing agent (%) Corrosion inhibitors CI (%) SER (Å / min) G -- -- -- <DL G 0.1 -- -- 140 G1 0.1 1 1 mM 30 G2 0.1 2 0.1 130 G3 0.1 3 0.1 145 G4 0.1 4 0.5 124 G5 0.1 5 0.5 138 G6 0.1 6 0.5 100 G7 0.1 7 0.05 <DL G8 0.1 8 0.05 <DL Example 5

[0048] After observing a significant decrease in SER values ​​in the presence of slurries G7 and G8, the formulation of slurry G was further modified to investigate the further increment in removal rate by introducing a Fenton catalyst (such as ferric(III) nonahydrate) to activate catalytic activity similar to the Fenton reaction. 140 ppm of catalyst was added to the formulation in Example 5, and the Mo removal rate and SER were tested. The removal rate increased by approximately 20% after adding the catalyst without compromising corrosion inhibition efficiency. SER values ​​at various oxidant concentrations and with 140 ppm catalyst are recorded in Table 5. Table 5: Effect of Catalyst Addition and Corrosion Inhibition Efficiency slurry Oxidizing agent (%) Catalyst(ppm) Corrosion inhibitors CI (%) SER (Å / min) Average removal rate (Å / min) G -- -- -- -- <DL 872 G7 0.1 -- 8 0.05 <DL 1646 G7 0.1 140 8 0.05 4 1833 G7 0.2 140 8 0.05 5 -- G7 0.3 140 8 0.05 9 -- G7 0.4 140 8 0.05 8 -- G7 0.5 140 8 0.05 15 -- G7 1 140 8 0.05 25 2255

[0049] Some examples of B-ruthenium polishing

[0050] Experimental setup:

[0051] All removal rate experiments below were performed on a Buehler Automet 250 benchtop polisher using 1.25" x 1.25" ruthenium PVD evaporation specimens at a platform speed of 100 RPM and a head speed of 60 RPM. A flow rate of 30 mL / min was maintained. Data were generated on a blanket-type SUBA-1200 polishing pad. Removal rates were measured using a five-point characterization method with a four-point probe (ResMap). Abrasive type Abrasive size (nm) solid load pH Removal rate (Å / minute) Titanium dioxide coated with alumina (this invention) ~200 2.5% 11.5 204 Aluminum-coated titanium dioxide (this invention) ~200 5% 11.5 245 Titanium dioxide ~230 2.5% 11.5 120 Titanium dioxide ~230 5% 11.5 140 Aluminum-coated titanium dioxide (this invention) ~400 2.5% 11.5 225 Aluminum-coated titanium dioxide (this invention) ~400 5% 11.5 273 Silicon 135 2.5% 11.5 48 Silicon 135 5% 11.5 53 Alumina 150 2.5% 11.5 25 Alumina 150 5% 11.5 32 Table 6: Removal rates at 3 psi DF and pH 11.5 for different abrasives (excluding other chemicals)

[0052] This set of experiments shows that aluminum-coated titanium dioxide particles have a catalytic reaction with the ruthenium surface to form a passivation layer of RuOx-, which can be easily removed by abrasive and pad friction.

[0053] For the next set of experiments, aluminum-coated titanium dioxide abrasive with a size of ~200 nm and a solid load of 2.5% was used. Oxidizing agent Oxidant concentration (wt%) pH Removal rate (Å / minute) hydrogen peroxide 0.001 11.5 210 hydrogen peroxide 0.1 11.5 230 hydrogen peroxide 1 11.5 345 hydrogen peroxide 2 11.5 400 hydrogen peroxide 5 11.5 410 hydrogen peroxide 2 7 320 hydrogen peroxide 2 9 270 hydrogen peroxide 2 10 315 hydrogen peroxide 2 12.5 450 periodic acid 0.001 6 715 periodic acid 0.1 6 925 periodic acid 1.5 6 1216 periodic acid 5 6 1412 periodic acid 1.5 11 778 periodic acid 1.5 12.5 830 Potassium periodate 0.001 9 685 Potassium periodate 0.42 9 1115 Potassium periodate 0.42 11 986 Potassium periodate 3 12.5 1286

[0054] Table 7: Removal rate at 3 psi DF and different pH values ​​for different oxidants

[0055] The above data reflects the process above pH 6; below pH 6, toxic RuO4 (ruthenium tetroxide) may form. Furthermore, pad staining decreases with increasing pH; it decreases sharply above pH 9, and staining is almost unobserved at pH 12.5. This can be attributed to the formation of soluble RuO4- / RuO2- ions at higher pH levels, rather than RuO2 and RuO4.

[0056] State

[0057] In a first embodiment, the present invention provides a composition comprising a liquid carrier; titanium dioxide abrasive particles, wherein the particles are at least partially coated with alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor.

[0058] In the second state sample, the present invention provides a composition of the first state sample, wherein the coated titanium dioxide abrasive particles are coated with alumina.

[0059] In the third state sample, the present invention provides a composition of the first or second state sample, wherein the coated titanium dioxide abrasive particles are coated with amorphous silica.

[0060] In the fourth state sample, the present invention provides a composition of any one of the first, second or third state samples, wherein the corrosion inhibitor is a cationic surfactant.

[0061] In the fifth state sample, the present invention provides a composition of any one of the first to fourth state samples, wherein the corrosion inhibitor is selected from phthalic anhydride ammonium chloride and phthalic anhydride ammonium bromide.

[0062] In the sixth state sample, the present invention provides a composition of any one of the first to fifth state samples, wherein the pH is about 2 to about 5.

[0063] In the seventh state sample, the present invention provides a composition of any one of the first to sixth state samples, the composition further comprising at least one oxidizing agent.

[0064] In the eighth state sample, the present invention provides a composition of the seventh state sample, wherein the oxidant is selected from hydrogen peroxide and periodic acid.

[0065] In the ninth embodiment, the present invention provides a method for chemically mechanically polishing a substrate comprising a surface including at least one transition metal, the method comprising: contacting the substrate with a composition comprising: a liquid carrier; titanium dioxide abrasive particles, wherein the particles are at least partially coated with alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor; moving the composition relative to the substrate; and abrading the substrate to remove a portion of the surface including at least one transition metal.

[0066] In the tenth state sample, the present invention provides a method for the ninth state sample, wherein the surface includes molybdenum.

[0067] In the eleventh state, the present invention provides a method for the ninth state, wherein the surface comprises ruthenium.

[0068] In the twelfth state sample, the present invention provides a method for the ninth, tenth or eleventh state sample, wherein the pH is about 2 to about 5.

[0069] In the thirteenth state, the present invention provides a method of any one of the ninth to twelfth states, wherein the coated titanium dioxide abrasive particles are coated with alumina.

[0070] In the fourteenth state, the present invention provides a method of any one of the ninth to thirteenth states, wherein the coated titanium dioxide abrasive particles are coated with amorphous silica.

[0071] In the fifteenth state sample, the present invention provides a method of any one of the ninth to fourteenth states samples, wherein the corrosion inhibitor is selected from phthalic anhydride ammonium chloride and phthalic anhydride ammonium bromide.

[0072] In the sixteenth embodiment, the present invention provides a method for chemically mechanically polishing a substrate comprising a surface including at least one of molybdenum or ruthenium, the method comprising: contacting the substrate with a composition comprising: a liquid carrier; titanium dioxide abrasive particles, wherein the particles are at least partially coated with alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor; moving the composition relative to the substrate; and abrading the substrate to remove a portion of the surface including at least one of molybdenum or ruthenium.

[0073] In the seventeenth embodiment, the present invention provides a kit comprising a component selected from components a, b, and c as defined in any of the first to eighth embodiments, in one or more containers.

[0074] Several illustrative embodiments of the invention have been described thus, and those skilled in the art will readily understand that other embodiments may be made and used within the scope of the appended claims. Many advantages of the invention covered in this document have been mentioned in the foregoing description. However, it should be understood that the invention is illustrative in many respects only. Of course, the scope of the invention is defined in the language expressed in the appended claims. [Simplified Explanation of the Diagram]

[0009] Figure 1 is a graph showing the etching rate (in angstroms per minute) of a molybdenum substrate versus the concentration of an etching inhibitor. The etching rate is represented by shaded bars. The name "SER" refers to the static etching rate (dot bar). This data corresponds to Example 4.

[0010] Figure 2 shows the surface finish of a molybdenum surface polished using the composition of the present invention. This information corresponds to Example 5.

[0011] Figure 3 is a graph of the removal rate (in angstroms per minute) of various abrasives and abrasive / oxidant combinations.

Claims

1. A composition comprising a liquid carrier; titanium dioxide abrasive particles, wherein the particles are at least partially coated with either alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor.

2. The composition of claim 1, wherein the coated titanium dioxide abrasive particles are coated with alumina.

3. The composition of claim 1, wherein the coated titanium dioxide abrasive particles are coated with amorphous silica.

4. The composition of claim 1, wherein the corrosion inhibitor is a cationic surfactant.

5. The composition of claim 4, wherein the corrosion inhibitor is selected from phthalic anhydride ammonium chloride and phthalic anhydride ammonium bromide.

6. The composition of claim 1, wherein the pH is about 2 to about 5.

7. The composition of claim 1, further comprising at least one oxidizing agent.

8. The composition of claim 7, wherein the oxidant is selected from hydrogen peroxide and periodic acid.

9. A method for chemically and mechanically polishing a substrate comprising a surface including at least one transition metal, the method comprising: The substrate is brought into contact with a composition comprising: a liquid carrier; titanium dioxide abrasive particles, wherein at least a portion of the particles are coated with either alumina or amorphous silica to provide coated titanium dioxide abrasive particles; wherein the coated titanium dioxide abrasive particles have an average diameter of about 50 nm to about 250 nm; and a corrosion inhibitor; the composition is moved relative to the substrate; and the substrate is abraded to remove a portion of the surface comprising at least one transition metal.

10. The composition of claim 9, wherein the surface comprises molybdenum.

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