Cmp composition including alcohol amine molybdenum etch inhibitor

Abstract

The present invention provides a chemical mechanical polishing composition comprising, consisting of, or substantially consisting of: a liquid carrier; colloidal silicon dioxide particles dispersed in the liquid carrier; an iron-containing polishing accelerator; a stabilizer combined with the iron-containing polishing accelerator; an alkanolamine compound comprising at least three alcohol groups and at least two amine groups; and a pH less than about 4.

Description

Technical Field

[0001] A chemical mechanical polishing composition comprising, consisting of, or substantially consisting of: a liquid carrier; colloidal silicon dioxide particles dispersed in the liquid carrier; an iron-containing polishing accelerator; a stabilizer combined with the iron-containing polishing accelerator; an alkanolamine compound comprising at least three alcohol groups and at least two amine groups; and a pH less than about 4. Prior Technology

[0002] Chemical mechanical polishing (CMP) compositions and methods for polishing (or planarizing) substrate surfaces are well known. Polishing compositions (also known as polishing slurries, CMP slurries, and CMP compositions) for polishing metal layers (such as tungsten) on semiconductor substrates may contain abrasive particles (e.g., containing silicon dioxide particles) dispersed in an aqueous carrier, and various chemical additives such as oxidants (e.g., hydrogen peroxide), rate accelerators (e.g., catalysts), corrosion inhibitors, and pH buffers.

[0003] As transistor sizes continue to shrink, the use of conventional metal interconnects has become increasingly challenging. In recent years, molybdenum has emerged as a candidate metal for advanced node applications, such as replacing or supplementing copper and / or tungsten in lower metal layers of interconnect structures (e.g., in M1, M2, and / or M3 layers). Furthermore, molybdenum can also be used as tungsten plugs and interconnect pads.

[0004] As mentioned above, CMP compositions typically employ oxidants such as hydrogen peroxide. Both tungsten and molybdenum are susceptible to hydrogen peroxide-induced corrosion. Due to the extremely small feature sizes of metallic structures, advanced node devices are often highly vulnerable to corrosion problems. Furthermore, some tungsten CMP operations require high tungsten / molybdenum removal rate selectivity and extremely low molybdenum static etching rates. There is a need for CMP compositions that can polish tungsten layers at appropriately high removal rates while exhibiting low molybdenum removal rates and improved molybdenum corrosion inhibition. Summary of the Invention

[0005] A chemical mechanical polishing composition is disclosed. The composition comprises, consists of, or is substantially composed of: a liquid carrier; abrasive particles dispersed in the liquid carrier; an iron-containing polishing accelerator; a stabilizer combined with the iron-containing polishing accelerator; and an alkanolamine compound comprising at least three alcohol groups and at least two amine groups, and having a pH of less than about 4. Implementation

[0006] This invention discloses chemical mechanical polishing (CMP) compositions and methods for polishing substrates using such compositions. In one exemplary embodiment, the CMP composition comprises, is substantially composed of, or consists of: a liquid carrier (such as an aqueous liquid carrier); abrasive particles dispersed in the liquid carrier; an iron-containing polishing accelerator; a stabilizer combined with the iron-containing polishing accelerator; and an alkanolamine compound comprising at least three alcohol groups and at least two amine groups, having a pH of less than about 4. In a preferred embodiment, the composition further comprises a polyamino acid compound, such as polyisocyanate. In a preferred embodiment, the alkanolamine compound comprises N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine. The disclosed method for polishing a substrate containing tungsten and / or molybdenum comprises: contacting the substrate with one of the disclosed polishing compositions; moving the polishing composition relative to the substrate; and abrading the substrate to remove tungsten and / or molybdenum from the substrate, thereby polishing the substrate.

[0007] The disclosed polishing composition and the corresponding (CMP method) offer significant advantages. In exemplary embodiments, the disclosed polishing composition advantageously provides high selectivity of tungsten for molybdenum, as well as inhibition of corrosion of both tungsten and molybdenum (especially molybdenum corrosion).

[0008] The polishing composition contains abrasive particles suspended (or dispersed) in a liquid carrier. The liquid carrier facilitates the application of colloidal silica particles and chemical additives to the surface of a substrate to be polished (e.g., planarized). The liquid carrier can be any suitable carrier (e.g., solvent), including lower alcohols (e.g., methanol, ethanol, etc.), ethers (e.g., dimethyl ether, tetrahydrofuran, etc.), water, and mixtures thereof. Preferably, the liquid carrier comprises water (preferably deionized water), is substantially composed of water (preferably deionized water), or is composed of water (preferably deionized water).

[0009] The abrasive particles may substantially comprise suitable abrasive particles, such as silica particles, alumina particles, titanium dioxide particles, ceramic particles, nanodiamond particles, polymeric particles, and / or metal oxide polymeric composite particles. The disclosed embodiments are not limited to the use of any particular abrasive particle. However, certain preferred embodiments may utilize colloidal silica particles. In such embodiments, the colloidal silica particles may substantially comprise any suitable colloidal silica particles. As used herein, the term colloidal silica particles refers to silica particles prepared via a wet process rather than pyrolysis or flame hydrolysis that produces structurally different particles. The disclosed embodiments may comprise aggregated or non-aggregated colloidal particles (e.g., colloidal silica particles). Non-aggregated particles are individual discrete particles that may be spherical or nearly spherical in shape, but may also have other shapes (such as typically elliptical, square, or rectangular cross-sections). Aggregated particles are particles that are clusters of multiple discrete primary particles or particles that combine to form aggregates with typically irregular shapes.

[0010] Colloidal silica particles can have virtually any suitable particle size. In industry, various methods are used to define the particle size of particles suspended in a liquid carrier. For example, particle size can be defined as the diameter of the smallest sphere encompassing the particles and can be measured using a variety of commercially available instruments, such as the CPS disc centrifuge, model DC24000HR (available from CPS Instruments, Prairieville, Louisiana) or the Zetasizer® from Malvern Instruments®. Colloidal silica particles can have an average particle size of about 5 nm or greater (e.g., about 10 nm or greater, about 20 nm or greater, about 30 nm or greater, about 40 nm or greater, about 50 nm or greater). Colloidal silica particles can have an average particle size of about 300 nm or less (e.g., about 250 nm or less, about 200 nm or less, about 180 nm or less, or about 150 nm or less). Therefore, colloidal silicon dioxide particles may have an average particle size within the range defined by any two of the above endpoints. For example, colloidal silicon dioxide particles may have an average particle size in the range of about 5 nm to about 300 nm (e.g., about 10 nm to about 200 nm, about 20 nm to about 200 nm, or about 50 nm to about 150 nm).

[0011] Polishing compositions may substantially contain any suitable amount of colloidal silica particles. If a polishing composition contains too little colloidal silica, the removal rate exhibited by the composition may be insufficient. Conversely, if a polishing composition contains too much colloidal silica, the polishing composition may exhibit unsatisfactory polishing performance and / or may be uneconomical. Polishing compositions configured for bulk removal operations (e.g., bulk tungsten and / or bulk molybdenum) typically contain a relatively small amount of colloidal silica particles at use, such as about 0.01 wt.% or more (e.g., about 0.02 wt.% or more, about 0.05 wt.% or more, about 0.1 wt.% or more, or about 0.15 wt.% or more). The concentration of colloidal silica particles in the polishing composition is typically less than about 10 wt.% (e.g., about 5 wt.% or less, about 3 wt.% or less, about 2 wt.% or less, or about 1.5 wt.% or less, or about 1 wt.% or less) when used. Therefore, the concentration of colloidal silica particles in the polishing composition can be defined by any of the aforementioned endpoints. For example, the polishing composition may contain about 0.01 wt.% to about 10 wt.% (e.g., about 0.02 wt.% to about 2 wt.%, about 0.05 wt.% to about 1 wt.%, or about 0.1 wt.% to about 1 wt.%) of colloidal silica particles when used.

[0012] In some advantageous embodiments, the colloidal silica particles may comprise cationic (positively charged) colloidal silica particles. The cationic colloidal silica particles may have a permanent positive charge or a non-permanent positive charge. For example, the cationic colloidal silica particles may have a permanent positive charge. A permanent positive charge means that the positive charge on the silica particles is not easily reversed, for example, by washing, dilution, filtration, or similar methods. A permanent positive charge may be the result of, for example, covalent bonding between a cationic compound and colloidal silica. A permanent positive charge is the opposite of a reversible positive charge, which can be generated, for example, by the interaction between a cationic compound and colloidal silica.

[0013] Cationic colloidal silica particles with a permanent positive charge can be prepared by treating (e.g., covalently bonding) colloidal silica particles with an aminosilane compound as disclosed in commonly assigned U.S. Patents 7,994,057 and 9,028,572 or U.S. Patent 9,382,450. Exemplary cationic colloidal silica particles can be treated with any suitable treatment method to obtain permanently charged particles. For example, a quaternary aminosilane compound and colloidal silica can be simultaneously added to some or all of the other components of a polishing composition. Alternatively, the colloidal silica particles can be treated with a quaternary aminosilane compound (e.g., by heating a mixture of colloidal silica and aminosilane) before being mixed with the other components of the polishing composition. Colloidal silica particles with a permanent positive charge can also be obtained by incorporating chemical substances (such as aminosilane compounds) into colloidal silica particles, as disclosed in commonly assigned U.S. Patent 9,422,456.

[0014] Cationic colloidal silica particles with a non-permanent positive charge can be prepared by introducing cationic surfactants into polishing compositions, as disclosed, for example, in commonly transferred U.S. Patent 9,631,122. Such cationic surfactants may comprise, for example, one or a combination of tetrabutylammonium, tetrapentammonium, tetrabutylphosphonium, tributylmethylenephosphonium, tributyloctylphosphonium, and benzyltributylammonium.

[0015] In advantageous embodiments, the cationic colloidal silica particles in the polishing composition (e.g., at a pH in the range of about 1 to about 4 and in the presence of the various chemical additives disclosed below) have a zeta potential of about 10 mV or greater (e.g., about 15 mV or greater, about 20 mV or greater, about 25 mV or greater, or about 30 mV or greater). The cationic colloidal silica particles in the polishing composition may also have a zeta potential of about 60 mV or less (e.g., about 55 mV or less, or about 50 mV or less). For example, the cationic colloidal silica particles in the polishing composition may have a zeta potential in the range of about 10 mV to about 60 mV (e.g., about 20 mV to about 60 mV, or about 25 mV to about 50 mV).

[0016] It should be understood that the zeta potential of a particle refers to the potential difference between the charge of the ions surrounding the particle and the charge of the bulk solution of the polishing composition (e.g., the liquid carrier and any other components dissolved therein), and this zeta potential typically depends on the pH and ionic strength of the aqueous medium (e.g., indicated by conductivity measurements). The zeta potential of dispersions (such as polishing compositions) can be measured using commercially available testing equipment (such as the Zetasizer from Malvern Instruments, the ZetaPlus zeta potential analyzer from Brookhaven Instruments, and / or the electroacoustic spectrometer from Dispersion Technologies, Inc.).

[0017] Polishing compositions are typically acidic, having a pH of less than about 5. Polishing compositions may have a pH of about 1 or greater (e.g., about 1.5 or greater, or about 2 or greater). Furthermore, polishing compositions may have a pH of about 5 or less (e.g., about 4.5 or less, about 4 or less, about 3.5 or less, or about 3 or less). Therefore, polishing compositions may have a pH within a range defined by any of the aforementioned endpoints, for example, in the range of about 1 to about 5 (e.g., about 1 to about 4, about 1.5 to about 4, about 2 to about 4, about 2 to about 3.5, or about 2 to about 3).

[0018] The pH of the polishing composition can be achieved and / or maintained by any suitable method. The polishing composition may substantially contain any suitable pH adjuster or buffering system. For example, suitable pH adjusters may include nitric acid, sulfuric acid, phosphoric acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, maleic acid, ammonium hydroxide, and the like, while suitable buffers may include phosphates, sulfates, acetates, malonates, oxalates, borates, ammonium salts, and the like.

[0019] The disclosed polishing compositions may include iron-containing polishing rate accelerators (e.g., tungsten or molybdenum polishing rate accelerators). As used herein, iron-containing accelerators are iron-containing chemical compounds that can increase the removal rate of tungsten or molybdenum during metal CMP operations. For example, iron-containing accelerators may include soluble iron-containing catalysts such as those disclosed in U.S. Patents 5,958,288 and 5,980,775. Such iron-containing catalysts are soluble in liquid carriers and may contain, for example, ferric (FeIII) or ferrous (FeII) compounds, such as ferric nitrate, ferric sulfate, ferric halide, including ferric fluoride, ferric chloride, ferric bromide, and ferric iodide, as well as ferric perchlorate, ferric perbromate, and ferric periodate; and organoferric compounds, such as ferric acetate, ferric carboxylate, ferric acetylacetonate, ferric citrate, ferric gluconate, ferric malonate, ferric oxalate, ferric phthalate, and ferric succinate, and mixtures thereof.

[0020] Iron-containing accelerators may also comprise iron-containing activators (e.g., radical-generating compounds) or iron-containing catalysts that are bonded to the surface of colloidal silica particles (e.g., coated or bonded to the surface), such as those disclosed in U.S. Patents 7,029,508 and 7,077,880. For example, iron-containing accelerators may be bonded to silanol groups on the surface of colloidal surface particles.

[0021] The amount of iron-containing accelerator in the polishing composition can vary depending on the oxidant and the chemical form of the accelerator used. When the oxidant is hydrogen peroxide (or one of its analogues) and a soluble iron-containing catalyst (such as ferric nitrate or ferric nitrate hydrate) is used, the catalyst may be sufficient to provide an amount of Fe ranging from about 0.5 to about 3000 ppm by weight of the total composition. For example, a polishing composition configured for bulk tungsten or molybdenum removal may contain about 1 ppm Fe or more when used (e.g., about 5 ppm or more, about 10 ppm or more, or about 15 ppm or more). A polishing composition may contain about 500 ppm Fe or less when used (e.g., about 200 ppm or less, about 100 ppm or less, or about 50 ppm or less). Therefore, the polishing composition may contain Fe within the range defined by any of the above endpoints (e.g., about 1 ppm to about 500 ppm, about 5 ppm to about 200 ppm, about 10 ppm to about 100 ppm, or about 15 ppm to about 50 ppm). For tungsten or molybdenum polishing slurry coatings that do not require a high metal removal rate, the catalyst may be present in a lower amount, for example, about 0.1 ppm to about 50 ppm Fe (e.g., about 0.2 ppm to about 20 ppm or about 0.2 to about 10 ppm).

[0022] Examples of polishing compositions containing iron-containing accelerators may further include stabilizers. In the absence of such stabilizers, the iron-containing accelerator and oxidant (if present) can react in a manner that causes rapid degradation of the oxidant over time. The addition of stabilizers often reduces the effectiveness of the iron-containing accelerator, making the choice of the type and amount of stabilizer added to the polishing composition potentially have a significant impact on CMP performance. The addition of stabilizers can lead to the formation of a stabilizer / accelerator complex that inhibits the reaction between the accelerator and the oxidant (if present) while allowing the accelerator to maintain sufficient activity to enhance the rapid polishing rate of tungsten or molybdenum.

[0023] Suitable stabilizers include phosphoric acid, organic acids (such as polycarboxylic acids), isophosphites, nitriles, and other ligands that bind to metals and reduce their reactivity to the decomposition of hydrogen peroxide, and mixtures thereof. Acid stabilizers can be used in their conjugate form, for example, carboxylates can be used instead of carboxylic acids. The term "acid" used herein to describe suitable stabilizers also means the conjugate base of the acid stabilizer. Stabilizers can be used alone or in combination and significantly reduce the decomposition rate of oxidants (such as hydrogen peroxide).

[0024] Preferred stabilizers include phosphoric acid, acetic acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, maleic acid, pentenoic acid, mucoconic acid, ethylenediaminetetraacetic acid (EDTA), propylenediaminetetraacetic acid (PDTA), and mixtures thereof. Preferred stabilizers may be added to the compositions of the present invention in amounts ranging from about 1 equivalent / iron-containing accelerator to about 3.0 weight percent or greater (e.g., about 1 equivalent to about 5 equivalents, or about 3 equivalents to about 10 equivalents). As used herein, the term "equivalent / iron-containing accelerator" means that each iron ion in the composition corresponds to one stabilizer molecule. For example, 2 equivalents / iron-containing accelerator means that each catalyst ion corresponds to two stabilizer molecules.

[0025] The polishing composition may further include an oxidizing agent, if appropriate. The oxidizing agent may be added to the polishing composition during the slurry preparation process or just before CMP operation (e.g., in a tank located in a semiconductor manufacturing facility). Preferred oxidizing agents include inorganic or organic peroxide compounds. Peroxide compounds as defined herein are compounds containing at least one peroxy group (-O--O-) or compounds containing an element in its highest oxidation state. Examples of compounds containing at least one peroxy group include, but are not limited to, hydrogen peroxide and its adducts (such as urea peroxide and percarbonate), organic peroxides (such as benzoyl peroxide, peracetic acid, and di- and tributyl peroxide), monopersulfates (SO5=), dipersulfates (S2O8=), and sodium peroxide. Examples of compounds containing an element in its highest oxidation state include, but are not limited to, periodic acid, periodate, perbromic acid, perbromate, perchloric acid, perchlorate, perboric acid and perborates, and permanganate. Hydrogen peroxide is the preferred oxidizing agent.

[0026] The oxidant can be present in substantially any suitable amount when used, for example, from about 0.0 wt.% to about 20 wt.% in the polishing composition. In exemplary embodiments configured for bulk removal of tungsten or molybdenum, comprising a hydrogen peroxide oxidant and a soluble iron-containing catalyst, the oxidant can be present in the polishing composition in an amount ranging from about 0.1 wt.% to about 10 wt.% (e.g., from about 0.5 wt.% to about 5 wt.% or from about 1 wt.% to about 4 wt.%). In exemplary embodiments configured for coating tungsten or molybdenum polishing slurries, the amount of hydrogen peroxide in the composition is typically low, for example, from about 0 wt.% to about 1 wt.%.

[0027] The polishing composition further comprises an alcoholamine inhibitor having at least three alcohol groups and at least two amino groups. For example, a suitable alcoholamine inhibitor can be given by the following formula: Where n is greater than or equal to 1, R1, R2, and R3 each comprise an alkyl alcohol, such as methanol, ethanol, propanol, or butanol, and R4 comprises an alkyl alcohol or an alkyl group, such as methyl, ethyl, propyl, butyl, etc. In a preferred embodiment, the alkanolamine compound comprises at least four alcohol groups. For example, in a preferred embodiment, the alkanolamine compound may comprise four ethanol groups (such that R1, R2, R3, and R4 each comprise an ethanol group). In other preferred embodiments, the alkanolamine compound is an alkanoldiamine compound (such that...). In the preferred embodiment, the alcohol amine compound is a diamine compound containing four alcohol groups (e.g., N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine).

[0028] Such alkanolamine compounds have been found to significantly inhibit molybdenum etching in certain polishing compositions while also achieving high tungsten and molybdenum polishing rates. The disclosed polishing compositions, containing the disclosed alkanolamine compound inhibitor (in the preferred embodiment, an alkanol diamine compound having four alcohol groups), are therefore particularly advantageous for advanced tungsten and molybdenum CMP operations.

[0029] The disclosed embodiments may substantially contain any suitable amount of an alcoholic amine compound. For example, when the alcoholic amine compound is a preferred diamine compound having four alcohol groups, the polishing composition may contain about 5 ppm or more (e.g., about 10 ppm or more, about 15 ppm or more, about 20 ppm or more, about 25 ppm or more, about 30 ppm or more, about 40 ppm or more) of an alcoholic amine compound by weight when used. Furthermore, the polishing composition may contain about 500 ppm or less (e.g., about 250 ppm or less, about 200 ppm or less, about 150 ppm or less, about 100 ppm or less, about 80 ppm or less, or about 60 ppm or less) of an alcoholic amine compound by weight when used. Therefore, the polishing composition may contain an alcoholic amine compound at a concentration that can be defined by any of the above endpoints. For example, the polishing composition may contain an alcoholic amine compound in amounts of about 5 ppm to about 500 ppm by weight when used (e.g., about 10 ppm to about 250 ppm, about 15 ppm to about 200 ppm, about 20 ppm to about 150 ppm, about 25 ppm to about 100 ppm, about 30 ppm to about 80 ppm, or about 40 ppm to about 60 ppm).

[0030] The polishing composition may further include, where appropriate, at least one supplemental (additional) metal etching inhibitor and / or configuration control agent. Suitable inhibitor compounds inhibit the conversion of solid tungsten or molybdenum into soluble compounds while simultaneously allowing efficient removal of the metal via CMP operations. The polishing composition may substantially contain any suitable inhibitor, such as the inhibitor compounds disclosed in commonly assigned U.S. Patents 9,238,754, 9,303,188, and 9,303,189.

[0031] Example classes of compounds that may be suitable etching inhibitors include compounds having nitrogen-containing functional groups (such as nitrogen-containing heterocycles, alkylammonium ions, aminoalkyl groups, and amino acids). Suitable aminoalkyl etching inhibitors include, for example, hexylamine, tetramethyl-p-phenylenediamine, octylamine, diethylenetriamine, dibutylbenzylamine, aminopropylsilanol, aminopropylsiloxane, dodecylamine, mixtures thereof, and synthetic and naturally occurring amino acids, including, for example, lysine, tyrosine, glutamic acid, glutamine, arginine, histidine, aspartic acid, cystine, and glycine (aminoacetic acid).

[0032] Suitable compounds may alternatively and / or additionally comprise amine compounds dissolved in the liquid carrier. One or more amine compounds may comprise primary, secondary, tertiary, or quaternary amines. The amine compounds may further comprise monoamines, diamines, triamines, tetraamines, or amine polymers having a large number of repeating amine groups (e.g., four or more amine groups).

[0033] Suitable compounds may alternatively and / or additionally be cationic surfactants. The use of cationic surfactants can advantageously reduce metal etching rates and improve flatness (e.g., reduce pitting and / or erosion). In some embodiments, the polishing compound may comprise a nitrogen-containing cationic surfactant, such as a tetramine compound or a polytetramine compound. A polytetramine means that the compound contains 2 to 4 tetramine groups, such that the polytetramine is a di(tetramine), tri(tetramine), or tetra(tetramine). Di- and tertiary amine compounds may include, for example, N,N′-methylenebis(dimethyltetradecanoic acid bromide), N,N,N′,N′,N′-pentamethyl-N-tallow-1,3-propane-diammonium dichloride, N,N′-hexamethylenebis(tributylammonium hydroxide), decamethylamine bromide, diiodide di(dodecyl)-tetramethyl-1,4-butanediamineonium, dibromide 1,5-dimethyl-1,5-diazabicyclo(3.2.2)nonane, dimethylcocoamine bis(chloroethyl) ether di(tertiary)ammonium salt, and the like. Tri- and tertiary amine compounds may include, for example, diiodide N(1),N(6)-di(dodecyl)-N(1),N(1),N(6),N(6)-tetramethyl-1,6-hexanediamineonium. Tetra- and tertiary amine compounds may include, for example, methanetetramethylamine (tetramethylammonium bromide). The polytetraamine compound may further comprise long-chain alkyl groups (e.g., having 10 or more carbon atoms). For example, a polytetraamine compound having long-chain alkyl groups may comprise N,N′-methylenebis(dimethyltetradecylammonium bromide), N,N,N′,N′,N′-pentamethyl-N-tallow-1,3-propane-diammonium dichloride, diiodide di(dodecyl)-tetramethyl-1,4-butanediamineonium, and diiodide N(1),N(6)-di(dodecyl)-N(1),N(1),N(6),N(6)-tetramethyl-1,6-hexanediamineonium.

[0034] Suitable compounds may alternatively and / or additionally comprise cationic polymers. Exemplary cationic polymers include, but are not limited to, poly(vinylimidazolium); chlorinated poly(methacryloyloxyethyltrimethylammonium) (polyMADQUAT); chlorinated poly(diallyldimethylammonium) (polyDADMAC) (i.e., polytetramethylammonium-6); poly(dimethylamine-co-epoxychloropropane); and poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea]. (i.e., polytetraammonium-2); copolymer of hydroxyethyl cellulose and diallyl dimethylammonium (i.e., polytetraammonium-4); copolymer of acrylamide and diallyl dimethylammonium (i.e., polytetraammonium-7); ethoxylated hydroxyethyl cellulose tetraammonium (i.e., polytetraammonium-10); copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate tetraammonium (i.e., polytetraammonium-11); copolymer of vinylpyrrolidone and vinylimidazole tetraammonium (i.e., polytetraammonium-16); polytetraammonium-24; terpolymer of vinylcaprolactam, vinylpyrrolidone and vinylimidazole tetraammonium (i.e., polytetraammonium-46); methyl 3-methyl-1-vinylimidazole methyl sulfate-N-vinylpyrrolidone copolymer (i.e., polytetraammonium-44); and copolymer of vinylpyrrolidone and diallyl dimethylammonium. Additionally, suitable cationic polymers include cationic polymers for personal care, such as Luviquat® Supreme, Luviquat® Hold, Luviquat® UltraCare, Luviquat® FC 370, Luviquat® FC 550, Luviquat® FC 552, Luviquat® Excellence, GOHSEFIMER K210™, GOHSENX K-434, and combinations thereof.

[0035] In some preferred embodiments, the cationic polymer may comprise amino acid monomers (such compounds may also be referred to as polyamino acid compounds). Suitable polyamino acid compounds may substantially comprise any suitable amino acid monomer groups, such as polyarginine, polyhistamine, polyalanine, polyglycine, polytyrosine, polyproline, and polylysine. In exemplary embodiments, polylysine may be a preferred polyamino acid. It should be understood that polylysine may comprise ε-polylysine and / or α-polylysine composed of D-lysine and / or L-lysine. Polylysine may therefore comprise α-poly-L-lysine, α-poly-D-lysine, ε-poly-L-lysine, ε-poly-D-lysine, and mixtures thereof. The preferred polylysine is ε-poly-L-lysine. It should be further understood that one or more polyamino acid compounds may be used in any available form (e.g., conjugate acid or conjugate base), and may be used in the form of a salt of polyamino acid rather than polyamino acid (or other than thereto).

[0036] In some embodiments, the polishing composition may comprise different first and second nitrogen-containing inhibitor compounds. For example, the first inhibitor compound in the composition may comprise a cationic polymer, such as a polyamino acid (preferably polylysine), and the second inhibitor compound in the composition may comprise an amino acid (preferably glycine, arginine, and histidine).

[0037] The disclosed polishing composition may substantially contain any additional chemical additives, chosen as appropriate. For example, the disclosed composition may contain dispersants and biodegradants. Such additional additives are entirely optional. The disclosed embodiments are not limited thereto and do not require the use of any or more of these additives. In embodiments further comprising biodegradants, the biodegradant may comprise any suitable biodegradant, such as isothiazolinone biodegradants known to those skilled in the art.

[0038] Polishing compositions can be prepared using any suitable technique, many of which are known to those skilled in the art. Polishing compositions can be prepared using batch or continuous methods. Generally, polishing compositions can be prepared by combining their components in any order. As used herein, the term "component" includes individual ingredients (e.g., colloidal silica, iron-containing accelerators, amine compounds, etc.).

[0039] For example, polishing composition components (such as iron-containing accelerators, stabilizers, one or more corrosion inhibitors, alkanolamine compounds, and / or biodegradants) can be added directly to the polishing dispersion (such as anionic or cationic colloidal silica dispersions). The silica dispersion and other components can be blended together using any suitable technique to achieve thorough mixing. Such blending / mixing techniques are well known to those skilled in the art. Oxidizing agents (if present) can be added at any time during the preparation of the polishing composition. For example, the polishing composition can be prepared prior to use, wherein one or more components (such as oxidizing agents) are added just before the CMP operation (e.g., within about 1 minute, or about 10 minutes, or about 1 hour, or about 1 day, or about 1 week before the CMP operation). Polishing compositions can also be prepared by mixing the components on the substrate surface (e.g., on a polishing pad) during the CMP operation.

[0040] The polishing composition can be advantageously supplied in a single-package system, comprising abrasive particles, an iron-containing accelerator, a stabilizer, one or more corrosion inhibitors, an alkanolamine compound, and other components selected as appropriate. Hydrogen peroxide can ideally be supplied separately from the other components of the polishing composition and can be combined with the other components of the polishing composition, for example, by the end user just before use (e.g., one week or less before use, one day or less before use, one hour or less before use, ten minutes or less before use, or one minute or less before use). Various other combinations of the components of the polishing composition in two, three, or more container types are within the knowledge of those generally skilled in the art.

[0041] The polishing composition of the present invention may also be provided as a concentrate intended to be diluted with an appropriate amount of water before use. In such embodiments, the polishing composition concentrate may contain a certain amount of abrasive particles, an iron-containing accelerator, a stabilizer, a corrosion inhibitor, an alkanolamine compound, and other components selected as appropriate, as well as an oxidant selected as appropriate, if not present in an appropriate amount, such that after diluting the concentrate with an appropriate amount of water, each component of the polishing composition will be present in the polishing composition in an amount within the appropriate range described above with respect to each component. For example, colloidal silica and other components selected as appropriate, together with a suitable amount of oxidant, may each be present in the polishing composition in an amount approximately 2 times (e.g., approximately 3 times, approximately 4 times, approximately 5 times, or even approximately 10 times) greater than the concentration listed above for use of each component, such that when the concentrate is diluted with an equal volume of water (e.g., with 2, 3, 4, or even 9 times the equal volume of water, respectively), each component will be present in the polishing composition in an amount within the range described above with respect to each component. In addition, as will be understood by those generally skilled in this art, the concentrate may contain an appropriate proportion of water present in the final polishing composition to ensure that the other components are at least partially or completely dissolved in the concentrate.

[0042] The disclosed polishing composition can be advantageously used for polishing substrates comprising a tungsten layer and / or a molybdenum layer and a dielectric material (such as silicon oxide and / or silicon nitride). In some applications, the tungsten layer and the molybdenum layer may be in contact with each other; for example, the molybdenum layer may be used as a pad for tungsten plugs and / or interconnects.

[0043] The polishing method of this invention is particularly suitable for use in conjunction with chemical mechanical polishing (CMP) equipment. Typically, this equipment includes a polishing platen, which is in motion during use and has a speed caused by track, linear, or circular motion; a polishing pad, which contacts the polishing platen and moves with the polishing platen during motion; and a carrier, which holds a substrate to be polished by contacting the surface of the polishing padn and moving relative to the surface of the polishing padn. Substrate polishing is performed as follows: the substrate is placed in contact with the polishing padn and the polishing composition of this invention; and then the polishing padn is moved relative to the substrate to polish at least a portion of the substrate (such as the tungsten and molybdenum layers described above).

[0044] The substrate can be planarized or polished using a chemical mechanical polishing composition and any suitable polishing pad (e.g., a polishing surface). Suitable polishing pads include, for example, woven and nonwoven polishing pads. Furthermore, suitable polishing pads can comprise any suitable polymer with different densities, hardness, thickness, compressibility, resilience after compression, and compressive modulus. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbons, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene, their co-formations, and mixtures thereof.

[0045] The following examples further illustrate the invention, but should not be construed as limiting its scope in any way. Example 1

[0046] Twelve polishing compositions were prepared. This example demonstrates the effectiveness of the disclosed alkanolamine compound inhibitor in reducing the static etching rate of molybdenum while achieving a high tungsten polishing rate. Each composition contains 400 ppm malonic acid, 300 ppm ferric nitrate nonahydrate (Fe(NO3)3·9H2O), 600 ppm tetrabutylammonium hydroxide, 15 ppm ε-poly-L-lysine, 25 ppm Kordex preservative, 0.30 wt% cationic colloidal silica treated with an aminosilane compound, and 0.4 wt% hydrogen peroxide. The pH of each composition was adjusted to 2.8 using ammonia. Each of compositions 1B to 1L further contains 50 ppm amine additives. The additives are listed in Table 1A. Table 1A Polishing Composition Amine additives 1A none 1B Ethylenediamine (DA) 1C Diethylenetriamine (DTA) 1D Triethylenetetramine (4DA) 1E 1,2-Di-(dimethylamino)ethane (DAE) 1F Pentamethyldiethylenetriamine (PMDTA) 1G 1,1,4,7,10,10-Hexamethyltriethylenetetramine (4TA) 1H Triethylenediamine (TEDA) 1I 1-Boc-piperazine (BPP) 1J Aminoethylpiperazine (APZ) 1K 1,4-Bis(3-aminopropyl)piperazine (BAPZ) 1L N,N,N',N'-Tetra(2-hydroxyethyl)ethylenediamine (THEDA)

[0047] The CMP performance of polishing compositions 1A to 1L was evaluated by polishing tungsten wafer samples using a GNP polishing tool (available from G&P Technologies) with a U5890 polishing pad (Entegris) and by off-center conditioning at 6 psi for 12 seconds using a 13M A165 conditioner. Tungsten polishing rates were obtained by polishing four wafer samples of each composition at a pressure of 2 psi, a polishing disc speed of 113 rpm, a polishing head speed of 105 rpm, and a slurry flow rate of 50 mL / min. The total polishing time was 60 seconds.

[0048] The static etching rate of molybdenum for each of the above compositions was measured. Molybdenum wafer samples were polished using the same polishing conditions described above for tungsten wafer samples. After polishing, the samples (four samples for each composition) were immersed in the polished composition for 10 minutes at room temperature. Tungsten polishing removal rate (RR), molybdenum polishing removal rate (RR), molybdenum static etching rate (SER), tungsten removal rate / molybdenum removal rate selectivity (W RR : Mo RR), and tungsten removal rate / molybdenum static etching rate ratio (W RR : Mo SER) are reported in Table 1B. Table 1B Polishing composition Inhibitor W RR (Å / min) Mo RR (Å / min) W RR : Mo RR Mo SER (Å / min) W RR : Mo SER 1A without 679 93 7 269 3 1B YES 743 67 11 150 5 1C DTA 302 294 1 80 4 1D 4DA 85 298 0.3 50 2 1E DAE 952 94 10 162 6 1F PMDTA 378 91 4 65 6 1G 4TA 291 172 2 68 4 1H SO 580 99 6 110 5 1I BPP 678 81 8 336 2 1J APZ 346 137 3 93 4 1K BAPZ 109 318 0.3 27 4 1L THEDA 530 41 13 40 13

[0049] As is evident from the data presented in Table 1B, only composition 1L containing N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine additive exhibits a high tungsten removal rate, an extremely low molybdenum removal rate, and a low molybdenum static etching rate, thereby further achieving high tungsten / molybdenum removal rate selectivity and a high tungsten removal rate / molybdenum static etching rate ratio. Example 2

[0050] Six polishing compositions were prepared. This example demonstrates the effectiveness of the disclosed alkanolamine compound inhibitor in reducing molybdenum loss due to etching. Each composition contains 400 ppm malonic acid, 300 ppm ferric nitrate nonahydrate (Fe(NO3)3·9H2O) by weight, 600 ppm tetrabutylammonium hydroxide by weight, 15 ppm ε-poly-L-lysine by weight, 25 ppm Kordex preservative, 0.30 wt% cationic colloidal silica treated with an aminosilane compound, and 0.4 wt% hydrogen peroxide. The pH of each composition was adjusted to 2.8 using ammonia. Compositions 2B to 2F each further contain 0.25 mM of an alcohol-containing additive (except composition 2C, which contains 50 ppm of the additive). The additives are listed in Table 2A. Table 2A Polishing Composition Alcohol-containing additives 2A none 2B Triethanolamine (TEA) 2C Polyvinyl alcohol (PVA) 2D Tris(hydroxymethyl)aminomethane 2E Aminethylethanolamine (AEA) 2F N,N,N',N'-Tetra(2-hydroxyethyl)ethylenediamine (THEDA)

[0051] The total molybdenum metal loss of each component in the above composition was measured. The molybdenum wafer samples were polished using the same polishing conditions described above for the tungsten wafer samples. After polishing, the molybdenum samples were immersed in the polishing composition at room temperature for 5, 7, and 10 minutes. The Mo static etching rate (SER) for each immersion time (5, 7, and 10 min) is reported in Table 2B. Table 2B Polishing Composition Inhibitors Mo SER 5 min (Å / min) Mo SER 7 min (Å / min) Mo SER 10 min (Å / min) 2A none 220 413 352 2B TEA 559 686 480 2C PVA 352 475 344 2D TRIS 118 186 193 2E AEA 61 64 100 2F THEDA 12 12 26

[0052] As is evident from the data presented in Table 2B, composition 2F, containing N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine additive, exhibits an extremely low Mo static etching rate compared to other alcohol-containing compounds.

[0053] It should be understood that, unless otherwise indicated herein, references to numerical ranges herein are merely intended as a way of individually referring to each individual value falling within that range, and that each individual value is incorporated into this specification as if individually described herein. Unless otherwise indicated herein or clearly contradicted by the context, all methods described herein may be performed in any suitable order. Unless otherwise asserted, the use of any and all instances or illustrative language provided herein (e.g., "such as") is intended only to better illustrate the invention and not to limit its scope. No language in this specification should be construed as indicating that any unclaimed element is necessary for practicing the invention.

[0054] Preferred embodiments of the present invention are described herein, including the best modes known to the inventors for carrying out the invention. Variations of these preferred embodiments will become apparent to those skilled in the art after reading the foregoing description. The inventors expect those skilled in the art to adopt these variations where appropriate, and the inventors intend to practice the invention in ways other than those specifically described herein. Therefore, the invention includes all modifications and equivalents of the subject matter described in the appended claims, where permitted by applicable law. Furthermore, unless otherwise indicated herein or otherwise clearly contradicted by the context, the invention covers any combination of the foregoing elements in all possible variations.

Claims

1. A chemical mechanical polishing composition comprising: Liquid carrier; Abrasive particles dispersed in the liquid carrier; Iron-containing polishing accelerator; A stabilizer combined with the iron-containing polishing accelerator; an alkanolamine compound containing at least three alcohol groups and at least two amine groups; and a pH less than about 4.

2. The composition of claim 1, wherein the alkanolamine compound comprises at least four alcohol groups.

3. The composition of claim 1, wherein the alcoholamine compound is an alcohol diamine compound.

4. The composition of claim 1, wherein the alkanolamine compound comprises N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine.

5. The composition of claim 1, comprising, when used, about 10 ppm to about 250 ppm of the alcohol amine compound by weight.

6. The composition of claim 1, comprising, when used, about 25 ppm to about 100 ppm of the alcohol amine compound by weight.

7. The composition of claim 1, further comprising a hydrogen peroxide oxidizing agent.

8. The composition of claim 1, having a pH in the range of about 1 to about 3.

5.

9. The composition of claim 1, wherein the iron-containing accelerator comprises a soluble iron catalyst, and the stabilizer comprises a polycarboxylic acid stabilizer combined with the soluble iron catalyst.

10. The composition of claim 1, further comprising a polyamino acid compound.

11. The composition of claim 10, wherein the polyamino acid compound comprises poly(lysine).

12. The composition of claim 11, comprising, when used, from about 1 ppm to about 20 ppm by weight of the polyamino acid compound.

13. The composition of claim 11, comprising, when used, about 2 ppm to about 10 ppm of the polyamino acid compound by weight.

14. The composition of claim 1, wherein the abrasive particles comprise colloidal silicon dioxide particles.

15. The composition of claim 1, wherein the abrasive particles comprise cationic colloidal silicon dioxide particles.

16. The composition of claim 15, wherein the cationic colloidal silica particles have an aminosilane compound covalently bonded to their outer surface.

17. A chemical mechanical polishing composition comprising: Liquid carrier; Abrasive particles dispersed in the liquid carrier; Iron-containing polishing accelerator; Stabilizers combined with the iron-containing polishing accelerator; polyisocyanate; and N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine.

18. The composition of claim 17, comprising: N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine in amounts of about 10 ppm to about 250 ppm by weight when used; and poly(ethylenediamine) in amounts of about 1 ppm to about 20 ppm by weight when used.

19. The composition of claim 18, wherein: The abrasive particles include colloidal silicon dioxide particles; the iron-containing accelerator includes a soluble iron catalyst, and the stabilizer includes a polycarboxylic acid stabilizer combined with the soluble iron catalyst; and the composition has a pH in the range of about 1 to about 3.

5.

20. A method for chemically mechanically polishing a substrate, the method comprising: (a) Contact the substrate with a polishing composition comprising: a liquid carrier; The abrasive particles dispersed in the liquid carrier; an iron-containing polishing accelerator; a stabilizer combined with the iron-containing polishing accelerator; an alkanolamine compound comprising at least three alcohol groups and at least two amine groups; and having a pH of less than about 4; (b) moving the polishing composition relative to the substrate; and (c) polishing the substrate by grinding it to remove a portion of at least one molybdenum layer or at least one tungsten layer from the substrate.