Composition for tungsten chemical mechanical polishing

Abstract

A chemical mechanical polishing composition for polishing a substrate having a tungsten layer includes a water-based liquid carrier, abrasive particles dispersed in the liquid carrier, an iron-containing accelerator, and a cationic polymer having an amino acid monomer. A method for chemical mechanical polishing a substrate including a tungsten layer includes contacting the substrate with the above-described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.

Description

Background Technology

[0001] Chemical mechanical polishing (CMP) compositions and methods for polishing (or planarizing) substrate surfaces are well known in the art. Polishing compositions (also known as polishing slurries, CMP slurries, and CMP compositions) for polishing metal layers (such as tungsten) located on semiconductor substrates may include abrasive particles suspended in an aqueous solution and chemical accelerators, such as oxidants, chelating agents, catalysts, etc.

[0002] In a conventional CMP operation, the substrate (wafer) to be polished is mounted on a carrier (polishing head), which is in turn mounted on a carrier assembly and placed in contact with a polishing pad within the CMP apparatus (polishing tool). The carrier assembly applies controlled pressure to the substrate, pressing the substrate against the polishing pad. The substrate and pad move relative to each other by an external driving force. This relative movement of the substrate and pad abrades and removes a portion of the material from the substrate surface, thereby polishing the substrate. Substrate polishing by the relative movement of the pad and substrate can be further aided by the chemical activity of the polishing composition (e.g., by oxidants and other compounds present in the CMP composition) and / or the mechanical activity of the abrasive suspended in the polishing composition.

[0003] In typical tungsten plug and interconnect processes, tungsten is deposited on a dielectric and within openings formed therein. Then, during a CMP (Continuous Metallurgical Processing) operation, excess tungsten on the dielectric layer is removed to form tungsten plugs and interconnects within the dielectric. As the feature sizes of semiconductor devices continue to shrink, meeting local and global flatness requirements during CMP operations (e.g., tungsten CMP operations) has become increasingly difficult. Array etching (also known as oxide etching), plug and line recessing (also known as dishing), and tungsten etching defects are known to impair flatness and overall device integrity. For example, excessive oxide etching and / or dishing can cause difficulties in subsequent photolithography steps and create electrical contact problems that can degrade electrical performance. Tungsten etching / corrosion can also degrade electrical performance or even cause device failure. Therefore, there is an industrial demand for tungsten CMP pastes (or compositions) that provide improved flatness during tungsten CMP operations. Summary of the Invention

[0004] A chemical mechanical polishing composition for polishing a substrate having a tungsten layer is disclosed. The polishing composition includes a water-based liquid carrier, abrasive particles dispersed in the liquid carrier, an iron-containing accelerator, and a cationic polymer having an amino acid monomer. In one embodiment, the abrasive particles may include colloidal silica (silica) and the cationic polymer may include polylysine. A method for chemically mechanically polishing a substrate including a tungsten layer is further disclosed. The method may include contacting the substrate with the polishing composition described above, moving the polishing composition relative to the substrate, and grinding the substrate to remove a portion of the tungsten from the substrate, thereby polishing the substrate. Detailed Implementation

[0005] A chemical mechanical polishing (CMP) composition for polishing substrates having a tungsten layer is disclosed. The polishing composition comprises a water-based liquid carrier, abrasive particles dispersed in the liquid carrier, an iron-containing accelerator, and a cationic polymer having an amino acid monomer (also referred to herein as polyamino acid). The CMP composition may substantially comprise any cationic polymer (including homopolymers and copolymers) containing amino acid monomer units. Formula (I) describes an exemplary homopolymer comprising amino acid monomers. Copolymers comprise two or more different monomer units. In suitable copolymers, at least one of the monomer units is an amino acid.

[0006]

[0007] In formula (I), at least one of L1, L2, X1, and X2 includes a positively charged group. Examples of positively charged groups may include titratable amino- and alkyl-amino substituents that can be protonated at the pH of the slurry (e.g., at about 2, or about 3, or about 4, 5, or 6). The positively charged group may also contain a group with a permanently positive charge, such as a tetraalkylammonium group. Non-limiting examples of other nitrogen-containing positively charged groups may include imidazolium, pyridinium, and guanidinium groups (including titratable corresponding alkyl salts). Other positively charged groups may include phosphonium and / or sulfonium groups. Where X1 and / or X2 contain positively charged groups, L1 and / or L2 may optionally be any linking group. In certain compounds in which X1 and / or X2 contain positively charged groups (such as titratable amino groups), L1 and L2 are optional. In certain other compounds in which L1 and / or L2 contain positively charged groups, X1 and X2 can be substantially any group, including, for example, hydrogen or alkyl. R1, R2, and R3 can be substantially any suitable substituent, including, for example, OH, H, or alkyl. R2 and R3 can substantially include any functional group that forms bonds between monomer units. The lowercase letter 'n' is used to indicate the repeating unit of the polymer resulting from the bonding of monomer units.

[0008] As noted above, polyamino acids can be homopolymers of suitable amino acid monomers (such as those depicted in formula (I)) or copolymers comprising suitable amino acid monomers with at least one other monomer unit in a suitable manner. Homopolymer polyamino acid compounds are generally preferred.

[0009] In a preferred embodiment, the polyamino acid compound includes an acid dissociation constant (pK). a The titratable group is greater than about 5, for example, in the range of about 5 to about 14, or preferably in the range of about 6 to about 11 (or about 6 to about 8). Table 1 lists several polyamino acids and their corresponding pK values. a Values. In Table 1, the pK values ​​of compounds 1-4 are... a The values ​​are within the preferred range. The pK values ​​of compounds 5 and 6... a The value is less than 5.

[0010] Table 1

[0011] compound Polyamino acids pKa refer to 1 α-Poly-L-L-lysine 10.1 Determined experimentally 2 ε-poly-L-lysine 7.2 Determined experimentally 3 Poly-L-arginine 12.5 L. Bromberg et al., Polymer, Vol. 48, 2007, pp. 7490-7498 4 Poly-L-histidine 6.5 D. Mavrogorgis et al., Polymer Chem., Vol. 5, 2014, pp. 6256-6277 5 α-poly-L-glutamic acid 4.6 E. Kokufuta et al., Biosystems, Vol. 10, 1978, pp. 299-306 6 Poly-aspartic acid 4.4 E. Kokufuta et al., BioSystems, Vol. 9, 1977, pp. 211-214

[0012] In Table 1, the pK values ​​of α-poly-L-lysine and ε-poly-L-lysine (compounds 1 and 2) were experimentally determined using potentiometric titration. aValue. Titration was performed in a 10 mL burette using 0.5 N KOH as the titrant in endpoint (EP) mode (EP = final pH = pH 12) with a Mettler-Toledo Model T5 autotitrator equipped with a DG115-SC pH probe. Data collection and analysis were performed using the autotitrator driven by LabX software, also from Mettler Toledo. A polylysine solution was prepared by mixing 52 mg of polylysine hydrochloride (i.e., α-poly-L-lysine hydrochloride from Alamanda Polymers at 4700 Daltons MW or ε-poly-L-lysine hydrochloride from Bonding Chemical) with 2.5 g of 1 N nitric acid (Aldrich Chemicals) and water to obtain a total mass of 150 g. The mixture was stirred and then sonicated for 10 min. The solution was then autotitrated as described above. The titration data were normalized by subtracting the corresponding acid control solution (acid control = 2.5 g of 1N nitric acid in water to a total mass of 150 g) from the water baseline titration data. The normalized titration data, obtained by fitting the added normalized KOH volume to (vs) pH using a nonlinear least squares algorithm, provided experimentally determined pK. a value.

[0013] In the most preferred embodiment, the polyamino acid compound may include, for example, polylysine, polyarginine, and / or polyhistidine. The abrasive particles may comprise substantially any suitable abrasive particles, such as colloidal silica. In one embodiment, the polishing composition comprises a soluble iron-containing catalyst, a stabilizer bound to the iron-containing catalyst, colloidal silica, polylysine, and a pH in the range of about 1.0 to about 5.0. The colloidal silica may optionally be treated with a functionalized silane compound to impart a permanent cationic or anionic charge. For example, treatment of colloidal silica with an aminosilane compound may impart a permanent positive charge.

[0014] It should be understood that the disclosed CMP compositions can be advantageously used in bulk tungsten removal and / or buff tungsten CMP operations (sometimes referred to in the art as first and second-step tungsten CMP operations). Bulk removal operations may require higher tungsten removal rates, while buffing operations may require lower defect levels. The disclosed CMP compositions can also be advantageously used in single-step tungsten CMP operations. The disclosed embodiments are not intended to be limited to any particular CMP operation.

[0015] The polishing composition contains abrasive particles suspended in a liquid carrier. The abrasive particles can comprise essentially any suitable abrasive material, such as metal oxide particles, diamond particles, and / or ceramic particles. Metal oxide particles may include, for example, silicon oxide and / or alumina abrasive particles. Ceramic particles may include materials such as cubic boron nitride or silicon carbide. The disclosed embodiments are not limited in terms of the abrasive particles.

[0016] In some embodiments (such as those disclosed below), the abrasive may include colloidal silica, pyrolytic silica, or mixtures thereof. As used herein, the term colloidal silica particles refers to silica particles prepared by a wet process rather than by a pyrolytic or flame hydrolysis method that produces structurally distinct particles. Colloidal silica particles may be aggregated or non-aggregated. Non-aggregated particles are individual discrete particles that may be spherical or nearly spherical in shape, but may also have other shapes (such as generally elliptical, square, or rectangular cross-sections). Aggregated particles are particles in which multiple discrete particles are clustered or bonded together to form aggregates with generally irregular shapes.

[0017] Abrasive particles can have virtually any suitable particle size. In industry, the particle size of particles suspended in a liquid carrier can be defined using various methods. For example, particle size can be defined as the diameter of the smallest sphere surrounding the particle and can be measured using a variety of commercially available instruments, such as the CPS disc centrifuge, DC24000HR model (obtained from CPS Instruments, Prairieville, Louisiana) or available from Malvern. of The average particle size of the abrasive particles can be about 5 nm or larger (e.g., about 20 nm or larger, about 40 nm or larger, about 50 nm or larger, or about 60 nm or larger). The abrasive particles can have an average particle size of about 200 nm or smaller (e.g., about 160 nm or smaller, about 140 nm or smaller, about 120 nm or smaller, or about 100 nm or smaller). Therefore, the abrasive particles can have an average particle size in the range of about 5 nm to about 200 nm (e.g., about 20 nm to about 160 nm, about 40 nm to about 140 nm, about 50 nm to about 120 nm, or about 60 nm to about 100 nm).

[0018] The polishing composition may substantially comprise any suitable amount of abrasive particles. The polishing composition typically comprises about 0.01% by weight or more of abrasive particles (e.g., about 0.05% by weight or more). More typically, the polishing composition may comprise about 0.1% by weight or more (e.g., about 0.2% by weight or more, about 0.5% by weight or more, or 1% by weight or more) of abrasive particles. The amount of abrasive particles in the polishing composition is typically about 30% by weight or less, and more typically about 20% by weight or less (e.g., about 10% by weight or less, about 5% by weight or less, or about 3% by weight or less). Preferably, the amount of abrasive particles in the polishing composition is in the range of about 0.01% by weight to about 30% by weight, and more preferably about 0.05% by weight to about 20% by weight (e.g., about 0.1% by weight to about 20% by weight, about 0.1% by weight to about 10% by weight, about 0.1% by weight to about 5% by weight, or about 0.2% by weight to about 3% by weight).

[0019] Using a liquid carrier facilitates the application of abrasives and any optional chemical additives to the surface of a substrate to be polished (e.g., planarized). Liquid carriers may include lower alcohols (e.g., methanol, ethanol, etc.), ethers (e.g., diethanolamine, ethanol ... Any suitable carrier (e.g., solvent) of alkanes, tetrahydrofurans, etc., water, and mixtures thereof. Preferably, the liquid carrier comprises water (more preferably deionized water), is substantially composed of water (more preferably deionized water), or is composed of water (more preferably deionized water).

[0020] In embodiments where the abrasive particles comprise silica (such as colloidal or ignited silica), the silica particles may optionally have a positive charge in the polishing composition. The charge on the dispersed particles (such as silica particles) is commonly referred to in the art as the zeta potential (or zeta potential). The zeta potential of a particle is 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., a liquid carrier and any other components dissolved therein). Typically, the zeta potential depends on the pH of the aqueous medium. For a given polishing composition, the isoelectric point of the particles is defined as the pH at which the zeta potential is zero. As the pH increases or decreases, deviating from the isoelectric point, the surface charge (and therefore the zeta potential) decreases or increases accordingly (to negative or positive zeta potential values). The zeta potential of dispersions (such as polishing compositions) can be obtained using commercially available instruments (such as the Zetasizer from Malvern Instruments, the ZetaPlus zeta potential analyzer from Brookhaven Instruments, and / or the electro-acoustic spectrometer from Dispersion Technologies, Inc.).

[0021] In some embodiments, the abrasive particles comprise colloidal silica particles having a permanent positive charge of about 6 mV or higher (e.g., about 10 mV or higher, about 15 mV or higher, or about 20 mV or higher). The colloidal silica particles in the polishing composition may have a permanent positive charge of about 50 mV or lower (e.g., about 45 mV or lower, or about 40 mV or lower). Preferably, the colloidal silica particles have a permanent positive charge in the range of about 6 mV to about 50 mV (e.g., about 10 mV to about 45 mV, about 15 mV to about 40 mV, or about 20 mV to about 40 mV).

[0022] A permanent positive charge refers to a positive charge on silica particles that is not easily reversed, for example, by rinsing, dilution, filtration, or similar methods. A permanent positive charge can result from, for example, covalent bonds between cationic compounds and colloidal silica. A permanent positive charge is the opposite of a reversible positive charge, which can result from, for example, electrostatic interactions between cationic compounds and colloidal silica.

[0023] Nevertheless, as used herein, a permanent positive charge of at least 6 mV means that the zeta potential of the colloidal silica particles remains above 6 mV after a three-step ultrafiltration test, which is further described in detail in commonly assigned U.S. Patent 9,238,754, which is incorporated herein by reference in its entirety.

[0024] Colloidal silica particles with a permanent positive charge in the polishing composition can be obtained, for example, by treating the particles with at least one aminosilane compound disclosed in commonly assigned U.S. Patents 7,994,057 and 9,028,572. Alternatively, colloidal silica particles with a permanent positive charge in the polishing composition can be obtained by incorporating a chemical substance (such as an aminosilane compound) into colloidal silica particles disclosed in commonly assigned U.S. Patent 9,422,456.

[0025] Polishing compositions are typically acidic, with a pH less than about 7. Polishing compositions typically have a pH of about 1 or higher (e.g., about 1.5 or higher, about 2 or higher, about 2.5 or higher, or about 3 or higher). Preferably, polishing compositions have a pH of about 6 or lower (e.g., about 5 or lower, about 4.5 or lower, about 4 or lower, or about 3.5 or lower). Polishing compositions may therefore have a pH in the range of about 1 to about 6 (e.g., about 2 to about 5, about 2 to about 4.5, or about 2.5 to about 4.5). Polishing compositions used for bulk tungsten removal preferably have a pH in the range of about 2 to about 4 (e.g., about 2 to about 3.5). Polishing compositions used for tungsten polishing operations preferably have a pH in the range of about 3 to about 5 (e.g., about 3 to about 4.5). The pH of the polishing composition can be achieved and / or maintained by any suitable means. Polishing compositions may substantially include any suitable pH adjuster or buffer 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, etc., while suitable buffers may include phosphates, sulfates, acetates, malonates, oxalates, borates, ammonium salts, etc.

[0026] Optional embodiments of the polishing composition may further include an iron-containing promoter. As used herein, an iron-containing promoter is an iron-containing compound that increases the tungsten removal rate during tungsten CMP operations. For example, an iron-containing promoter 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 a liquid carrier and may include, for example: ferric (FeIII) or ferrous (FeII) compounds, such as ferric nitrate and ferric sulfate; iron halides, including fluorides, chlorides, bromides, and iodides, as well as perchlorates, perbromates, and periodates; 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.

[0027] Iron-containing accelerators may also include iron-containing catalysts or iron-containing activators (e.g., free radical-generating compounds) that are bonded to the surface of colloidal silica particles (e.g., coated or bonded), 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.

[0028] 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 using a preferred oxidant, hydrogen peroxide (or its analogues), and a soluble iron-containing catalyst (such as ferric nitrate), the catalyst can be sufficient, by weight of the composition, to provide an amount in the range of about 0.5 to about 3000 ppm Fe present in the composition. The polishing composition may include about 1 ppm or more Fe (e.g., about 2 ppm or more, about 5 ppm or more, or about 10 ppm or more). The polishing composition preferably includes about 500 ppm or less Fe (e.g., about 200 ppm or less, about 100 ppm or less, or about 50 ppm or less). The polishing composition may therefore include the range of about 1 to about 500 ppm Fe (e.g., about 2 to about 200 ppm, about 5 to about 100 ppm, or about 10 to about 50 ppm). Polishing compositions for bulk tungsten removal may preferably include about 5 to about 50 ppm Fe (e.g., about 10 to about 40 ppm Fe). Polishing compositions for tungsten polishing operations preferably include about 0.5 to about 20 ppm Fe (e.g., about 1 to about 10 ppm Fe).

[0029] Embodiments of polishing compositions including iron-containing accelerators may further include stabilizers. Without such stabilizers, the iron-containing accelerator and oxidant (if present) can react in a manner that causes the oxidant to rapidly degrade (deteriorate) over time. The addition of stabilizers often reduces the effectiveness of the iron-containing accelerator, making the type and amount of stabilizer added to the polishing composition significantly influential on CMP performance. The addition of stabilizers can lead to the formation of stabilizer / accelerator complexes, which inhibit the reaction between the accelerator and the oxidant (if present), while allowing the accelerator to retain sufficient activity to promote rapid tungsten polishing rates.

[0030] Available stabilizers include phosphoric acid, organic acids, phosphonate (ester) compounds, nitriles, and other ligands that bind to metals and reduce their reactivity to the decomposition of hydrogen peroxide, as well as mixtures thereof. Acid stabilizers can be used in their conjugate form; for example, carboxylates (esters) can be used instead of carboxylic acids. The term "acid" used herein to describe available stabilizers also refers to the conjugate base of the acid stabilizer. For example, the term "adipic acid" refers to adipic acid and its conjugate base. Stabilizers can be used alone or in combination and significantly reduce the decomposition rate of oxidants such as hydrogen peroxide.

[0031] 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, pentanoic acid, mucoconic acid, ethylenediaminetetraacetic acid (EDTA), propylenediaminetetraacetic acid (PDTA), and mixtures thereof. Preferred stabilizers may be added to the compositions of the invention in an amount ranging from about 1 equivalent / iron-containing promoter to about 3.0% by weight or higher (e.g., about 3 to about 10 equivalents). As used herein, the term "equivalent / iron-containing promoter" means one stabilizer molecule per iron ion in the composition. For example, 2 equivalents / iron-containing promoter means two stabilizer molecules per catalyst ion.

[0032] The polishing composition may optionally further include an oxidizing agent. The oxidizing agent may be added to the polishing composition during the slurry preparation process or just before the CMP operation (e.g., in a tank located at a semiconductor manufacturing facility). Preferred oxidizing agents include inorganic or organic per-compounds. Per-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 hydrogen peroxide and percarbonate), organic peroxides (such as benzoyl peroxide, peracetic acid, and di-tert-butyl peroxide), and monopersulfates (SO5). ＝ persulfate (S2O8) ＝ And sodium peroxide. Examples of compounds containing elements in their highest oxidation state include (but are not limited to) periodic acid, periodate, perbromic acid, perbromate, perchloric acid, perchlorate, perboric acid and perborates, and permanganate. The most preferred oxidizing agent is hydrogen peroxide.

[0033] The oxidant may be present in the polishing composition in an amount ranging from about 0.1 to about 10% by weight, for example. In a preferred embodiment in which a hydrogen peroxide oxidant and a soluble iron-containing accelerator are used, the oxidant may be present in the polishing composition in an amount ranging from about 0.1 to about 6% by weight (e.g., about 0.2 to about 5% by weight, about 0.3 to about 4% by weight, or about 0.5 to about 3% by weight).

[0034] The polishing composition further comprises a cationic polymer (also referred to herein as a polyamino acid compound) having amino acid monomer units dissolved in a liquid carrier. It should be understood that the polyamino acid compound is a polymer derived from amino acid monomers. The polyamino acid compound is intended to suppress tungsten plug and wire indentation (i.e., depression), particularly tungsten wire (interconnect) indentation, and to reduce array erosion. A suitable polyamino acid compound can further (albeit not necessarily) suppress tungsten etching. Essentially any suitable polyamino acid can be used, such as those disclosed above according to formula (I). Such suitable polyamino acids may include polyarginine, polyornithine, polyhistidine, and polylysine. Preferred polyamino acid compounds include polylysine, polyarginine, and polyhistidine. The most preferred polyamino acid compound includes polylysine.

[0035] It should be understood that polylysine may include ε-polylysine and / or α-polylysine composed of D-lysine and / or L-lysine. Polylysine may therefore include α-poly-L-lysine, α-poly-D-lysine, ε-poly-L-lysine, ε-poly-D-lysine, and mixtures thereof. In some preferred embodiments, the polylysine is ε-poly-L-lysine. Further, it should be understood that polyamino acid compounds (or multiple polyamino acid compounds) may be used in any available form (e.g., conjugate acid or conjugate base), and salts of polyamino acids may be used instead of polyamino acids (or salts of polyamino acids may be used in addition to polyamino acids). In the context of this document, the term "acid" as used to describe suitable polyamino acid additives is intended to mean polyamino acids and any form obtainable by adjusting the pH to alter any titratable functional groups that may be present. Such forms include their conjugate bases or conjugate acids and any other salts thereof. For example, the term "polylysine" refers to polylysine amino acids and their conjugate acids formed by the protonation of amine functional groups.

[0036] Polyamino acid compounds can have virtually any suitable molecular weight and polydispersity index. For example, the molecular weight of polyamino acids can be in the range of about 1 to about 100 kDa. However, it should be understood that the disclosed embodiments are not limited to the molecular weight or polydispersity index of the polyamino acid compound.

[0037] The amount of polyamino acid compound in the polishing composition can vary depending on the specific polyamino acid used, the oxidant used, and the chemical form of the accelerator. When using a preferred polyamino acid, polylysine (e.g., ε-poly-L-lysine) and a preferred hydrogen peroxide oxidant and a soluble iron-containing catalyst, polylysine can be present in the composition in an amount ranging from about 1 to about 1000 ppm by weight of the composition. The polishing composition preferably includes about 1 ppm or more of polylysine (e.g., about 5 ppm or more, about 10 ppm or more, about 15 ppm or more, or about 20 ppm or more). The polishing composition preferably includes about 1000 ppm or less of polylysine (e.g., about 500 ppm or less, about 200 ppm or less, about 100 ppm or less, about 75 ppm or less, about 50 ppm or less, or about 25 ppm or less). The polishing composition may therefore include polylysine in the range of about 1 to about 1000 ppm (e.g., about 1 to about 500 ppm, about 1 to about 200 ppm, about 1 to about 100 ppm, about 1 to about 50 ppm, about 5 to about 500 ppm, about 5 to about 200 ppm, about 5 to about 100 ppm, about 5 to about 50 ppm, or about 5 to about 25 ppm).

[0038] The polishing composition may optionally include a compound that provides further tungsten etch inhibition (i.e., in addition to any tungsten etch inhibition provided by polyamino acids). Such optional compounds (when included) are intended to inhibit the conversion of solid tungsten into soluble tungsten compounds while simultaneously allowing efficient removal of solid tungsten via CMP operations. Suitable compounds include those having nitrogen-containing functional groups (such as nitrogen-containing heterocycles), alkylammonium ions, aminoalkyl groups, and amino acids. Suitable tungsten etch inhibitors are disclosed in more detail in U.S. Patents 6,136,711 and 9,238,754.

[0039] The polishing composition may optionally further include a biocide. The biocide may include any suitable biocide, such as isothiazolinone biocides. The amount of biocide in the polishing composition is typically in the range of about 1 ppm to about 50 ppm, and preferably from about 1 ppm to about 20 ppm.

[0040] 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 by 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., abrasive particles, iron-containing accelerators, polyamino acids, etc.).

[0041] For example, silica can be dispersed in an aqueous liquid carrier. Other components (such as iron-containing accelerators, stabilizers, polyamino acids, and biocides) can then be added and mixed by any method capable of incorporating the components into the polishing composition. The oxidant 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 the oxidant) 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 of the CMP operation). The polishing composition can also be prepared by mixing the components at the substrate surface (e.g., on a polishing pad) during the CMP operation.

[0042] The polishing composition of the present invention can also be provided as a concentrate intended for dilution with an appropriate amount of water prior to use. In such embodiments, the polishing composition concentrate may include abrasive particles, a polyamino acid compound, optional iron-containing accelerators and stabilizers, optional biocide, and water, with or without an oxidant, the amounts of which are such that when the concentrate is diluted with an appropriate amount of water and an oxidant (if not already present in an appropriate amount), each component of the polishing composition will be present in the polishing composition in an amount within the appropriate range listed above for each component. For example, the abrasive particles, the polyamino acid compound, and the optional iron-containing accelerators and stabilizers may each be present in the polishing composition in an amount approximately twice (e.g., approximately three times, approximately four times, or approximately five times) the concentrations listed above for each component, such that when the concentrate is diluted with an equal volume of water (e.g., 1 equal volume of water, 2 equal volumes of water, 3 equal volumes of water, or even 4 equal volumes of water, respectively) with an appropriate amount of oxidant, each component will be present in the polishing composition in an amount within the ranges listed above for each component. In addition, as those skilled in the art will understand, 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.

[0043] Although the polishing composition of the present invention can be used to polish any substrate, it is particularly suitable for polishing substrates comprising at least one metal containing tungsten and at least one dielectric material. The tungsten layer may be deposited on one or more barrier layers, such as those comprising titanium and / or titanium nitride (TiN). The dielectric layer may be a metal oxide, such as a silicon oxide layer derived from tetraethyl orthosilicate (TEOS), a porous metal oxide, a porous or non-porous carbon-doped silicon oxide, a fluorine-doped silicon oxide, glass, an organic polymer, a fluorinated organic polymer, or any other suitable high-k or low-k insulating layer.

[0044] The polishing method of the present invention is particularly suitable for use in conjunction with a chemical mechanical polishing (CMP) apparatus. Typically, the apparatus includes: a pressure plate, which, when in use, is in motion and has a speed generated by tracked, linear, or circular motion; a polishing pad, which contacts the pressure plate and moves with the pressure plate during motion; and a carrier holding a substrate to be polished by contacting the surface of the polishing pad and moving relative to it. Polishing of the substrate is performed by placing the substrate in contact with the polishing pad and the polishing composition of the present invention, and then moving the polishing pad relative to the substrate to abrade at least a portion of the substrate (such as tungsten, titanium, titanium nitride, and / or dielectric materials as described herein) to polish the substrate.

[0045] Chemical mechanical polishing compositions can be used to planarize or polish substrates with any suitable polishing pad (e.g., polishing surface). Suitable polishing pads include, for example, woven and nonwoven polishing pads. Furthermore, suitable polishing pads can comprise any suitable polymer having a variety of densities, hardness, thicknesses, compressibility, compression resilience, and compressive modulus. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbons, polycarbonates, polyesters, polyacrylates, polyethers, polyethylene, polyamides, polyurethanes, polystyrene, polypropylene, their co-formations, and mixtures thereof.

[0046] It should be understood that this disclosure includes multiple implementation schemes. These implementation schemes include, but are not limited to, the following implementation schemes.

[0047] In a first embodiment, a chemical mechanical polishing composition includes: a water-based liquid carrier; abrasive particles dispersed in the liquid carrier; an iron-containing accelerator; and a cationic polymer having amino acid monomer units.

[0048] The second implementation may include the first implementation, wherein the abrasive particles comprise colloidal silica abrasive.

[0049] The third embodiment may include the second embodiment, wherein the colloidal silica abrasive has a permanent positive charge of at least 10 mV.

[0050] The fourth embodiment may include any of the first three embodiments, wherein the iron-containing promoter comprises a soluble iron-containing catalyst.

[0051] The fifth embodiment may include the fourth embodiment and further include a stabilizer combined with the soluble iron-containing catalyst, the stabilizer being selected from: phosphoric 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, propylenediaminetetraacetic acid, and mixtures thereof.

[0052] The sixth embodiment may include any of the first five embodiments and further include a hydrogen peroxide oxidant.

[0053] The seventh embodiment may include any of the first six embodiments and have a pH in the range of about 1.0 to about 5.0.

[0054] The eighth embodiment may include any of the preceding seven embodiments, wherein the cationic polymer comprises a compound according to the following formula

[0055]

[0056] At least one of L1, L2, X1 and X2 includes a positively charged group and R1, R2 and R3 are H, OH or alkyl.

[0057] The ninth embodiment may include the eighth embodiment, wherein the acid dissociation constant (pK) of the cationic polymer a (Greater than approximately 5.)

[0058] The tenth embodiment may include the eighth embodiment, wherein the acid dissociation constant (pK) of the cationic polymer a The range is 6 to 11.

[0059] The eleventh embodiment may include the eighth embodiment, wherein the cationic polymer comprises at least one of polylysine, polyarginine, and polyhistidine.

[0060] The twelfth embodiment may include the eleventh embodiment, wherein the cationic polymer comprises polylysine.

[0061] The thirteenth embodiment may include the twelfth embodiment, wherein the cationic polymer comprises ε-poly-L-lysine.

[0062] The fourteenth embodiment may include the eighth embodiment, comprising about 1 to about 200 ppm of the cationic polymer by weight.

[0063] The fifteenth embodiment may include the eighth embodiment, comprising about 5 to about 50 ppm of the cationic polymer by weight.

[0064] The sixteenth embodiment may include the eighth embodiment, wherein the cationic polymer has a molecular weight in the range of about 1 to about 100 kDa.

[0065] In a seventeenth embodiment, a chemical mechanical polishing composition comprises: a water-based liquid carrier; colloidal silica abrasive particles dispersed in the liquid carrier; a soluble iron-containing catalyst; a stabilizer bound to the soluble iron-containing catalyst; and a cationic polymer having amino acid monomer units, the cationic polymer comprising at least one of polylysine, polyarginine, and polyhistidine; wherein the composition has a pH in the range of about 1 to about 5.

[0066] The eighteenth embodiment may include the seventeenth embodiment, wherein the cationic polymer is polylysine.

[0067] In a nineteenth embodiment, a method for chemically mechanically polishing a substrate comprising a tungsten layer includes (a) contacting the substrate with a polishing composition comprising: (i) a water-based liquid carrier; (ii) abrasive particles dispersed in the liquid carrier; (iii) an iron-containing accelerator; and (iv) a cationic polymer having amino acid monomer units; (b) moving the polishing composition relative to the substrate; and (c) grinding the substrate to remove a portion of the tungsten from the substrate and thereby polishing the substrate.

[0068] The twentieth embodiment may include the nineteenth embodiment, wherein the abrasive particles comprise colloidal silicon dioxide with a permanent positive charge of at least 10 mV.

[0069] The twenty-first embodiment may include the nineteenth or twentieth embodiment, wherein: (i) the iron-containing promoter comprises a soluble iron-containing catalyst; and (ii) the polishing composition further comprises a stabilizer combined with the soluble iron-containing catalyst, the stabilizer being selected from: phosphoric 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, propylenediaminetetraacetic acid, and mixtures thereof.

[0070] The twenty-second embodiment may include any one of the nineteenth to twenty-first embodiments, wherein: (i) the polishing composition further comprises a hydrogen peroxide oxidant; and (ii) the polishing composition has a pH in the range of about 1.0 to about 5.0.

[0071] The twenty-third embodiment may include any one of the nineteenth to twenty-second embodiments, wherein the cationic polymer comprises at least one of polylysine, polyarginine, and polyhistidine.

[0072] The twenty-fourth embodiment may include the twenty-third embodiment, wherein the cationic polymer comprises polylysine.

[0073] The twenty-fifth embodiment may include the twenty-third embodiment, comprising about 1 to about 200 ppm of the cationic polymer by weight.

[0074] The following embodiments further illustrate the invention, but should not be construed as limiting its scope in any way.

[0075] Example 1

[0076] Nine polishing compositions (controls A and B and Examples 1A, 1B, 1C, 1D, 1E, 1F, and 1G) were prepared as concentrates, which were diluted with water 2:1 just before use. Compositions 1A-1G comprised different concentrations of ε-poly-L-lysine (ranging from 30 to 3000 ppm by weight). Each of the nine polishing compositions was prepared by adding concentrated colloidal silica (such as commercially available from Akzo Nobel, Fuso, and Nalco) to a mixture comprising malonic acid, ferric nitrate, TBAH (tetrabutylammonium hydroxide), appropriate amounts of ε-poly-L-lysine, and... Prepared from a mixture of biocides. Colloidal silica has an average particle size of 120 nm. Control A does not include ε-poly-L-lysine. Control B includes 3000 ppm (by weight) of lysine in place of ε-poly-L-lysine. Each of the nine polishing compositions includes 2700 ppm (by weight) of tetrabutylammonium hydroxide (TBAH), 81 ppm (by weight) of malonic acid, 3.7 ppm (by weight) of ferric nitrate nonahydrate (Fe(NO3)3·9H2O), 7.5 wt% colloidal silica, and 15 ppm (by weight) of Kathon LX. The pH was adjusted to 3.05 using nitric acid. The concentration of ε-poly-L-lysine varied as described in more detail below.

[0077] The tungsten etching rate of each of the nine polishing compositions described above was evaluated. This example demonstrates the effect of ε-poly-L-lysine on the tungsten etching rate. To obtain the tungsten etching rate of each polishing composition, the composition was first diluted to one part polishing composition to two parts deionized water. The polishing composition was then heated to 45°C, and subsequently, hydrogen peroxide was added to a concentration of 0.5% by weight. After waiting 5 minutes for the temperature to return to 45°C, a two-inch wafer with a tungsten layer was immersed in the polishing composition (tungsten side up) for 5 minutes. The tungsten removal rate was determined by resistivity measurements performed before and after immersion in the polishing composition.

[0078] Tungsten etching rates are shown in Table 2. Control A does not include ε-poly-L-lysine or lysine. Control B does not include ε-poly-L-lysine and 1000 ppm (by weight) lysine (after dilution). Compositions 1A-1G comprise 10 ppm (1A), 25 ppm (1B), 50 ppm (1C), 100 ppm (1D), 250 ppm (1E), 500 ppm (1F), and 1000 ppm (1G) of ε-poly-L-lysine as indicated in Table 2. All concentrations of ε-poly-L-lysine listed in Table 2 are after dilution with deionized water at a 2:1 ratio.

[0079] Table 2

[0080]

[0081] As the results listed in Table 2 clearly show, compositions 1C to 1G with ε-poly-L-lysine concentrations in the range of 50 to 1000 ppm (by weight) exhibited W etch rates that were one-twentieth or less of the W etch rate of control A (without inhibitor) and one-quarter or less of the W etch rate of control B (1000 ppm (by weight) lysine).

[0082] Example 2

[0083] Twenty-four polishing compositions were prepared (Examples 2A to 2X). The polishing compositions were identical except for the type and concentration of the additives. The tungsten etching rate of each polishing composition was measured, and the effect of the additives was evaluated. The tungsten etching rate was measured using the same procedure as described in Example 1 above (wherein, as also described in Example 1, hydrogen peroxide was added to a concentration of 0.5% by weight).

[0084] By concentrating colloidal silicon dioxide ( PL-2) is added to substances including malonic acid, ferric nitrate, and... Each component of the polishing composition was prepared from a mixture of biocides, such that the colloidal silica concentration was 3.0% by weight. Each component of the polishing composition comprised 25 ppm (by weight) malonic acid, 12 ppm (by weight) ferric nitrate nonahydrate (Fe(NO3)3·9H2O), and 15 ppm (by weight) Kathon LX. The pH was adjusted to 2.5 using nitric acid. Then, an appropriate additive compound was added to the polishing composition prior to etching testing. The concentration of the additive was 50 or 100 ppm (by weight).

[0085] Table 3 lists the additive compounds and their corresponding concentrations, along with the tungsten etch rates measured for each polishing composition. As the results in Table 3 clearly demonstrate, polishing compositions 2A / 2B, 2O / 2P, and 2Q / 2R, which include ε-polylysine and α-polylysine additives, exhibit very low tungsten static etch rates. Furthermore, polishing compositions 2S / 2T and 2W / 2X, which include polyhistidine and polyarginine additives, also exhibit very low tungsten static etch rates.

[0086] Table 3

[0087]

[0088] Example 3

[0089] In this example, the tungsten polishing rate and line indentation (dimpling) of three polishing compositions were evaluated. This example demonstrates the inhibitory effect of polylysine on indentation during tungsten CMP operation. CMP compositions were obtained using a procedure similar to that described above with respect to Example 1 (where concentrated colloidal silica was added to a mixture comprising malonic acid and ferric nitrate). Each of the three polishing compositions comprised 445 ppm (by weight) malonic acid, 206 ppm (by weight) ferric nitrate nonahydrate (Fe(NO3)3·9H2O), 0.33 wt% cationic aminosilane-treated colloidal silica (prepared as disclosed in U.S. Patents 7,994,057 and 9,028,572), 15 ppm (by weight) Kathon LX, and 2.0 wt% hydrogen peroxide at pH 2.3 (pH adjusted using nitric acid). The treated colloidal silica had an average particle size of 120 nm. The control C polishing composition did not contain other components. The polishing composition of control D comprises 25 ppm (by weight) of the cationic polymer polydiallyldimethylammonium chloride (polyDADMAC). Polishing composition 3A comprises 25 ppm (by weight) of ε-poly-L-lysine.

[0090] Tungsten polishing rates are achieved using a polishing blanket-coated tungsten wafer. Line recess values ​​are obtained by polishing a 2k Silyb 854 tungsten patterned wafer (available from Silyb Wafer Services) with a combined titanium / titanium nitride barrier layer. The process is carried out at a downforce of 2.0 psi, a platen speed of 115 rpm, and a head speed of 121 rpm. CMP polishing tools and The E6088 polishing pad was used to polish the wafers. The slurry flow rate was 90 ml / min. Each patterned wafer was polished to the optical endpoint with an additional 30% overpolishing. The indentation of the line was measured using an atomic force microscope (AFM) profilometer across a 1×1 micrometer line feature. The tungsten polishing rate and the indentation values ​​of the line are shown in Table 4.

[0091] Table 4

[0092]

[0093] As clearly shown in the results listed in Table 4, the use of ε-poly-L-lysine reduced the indentation of the line by nearly four times compared to control C and by nearly three times compared to control D.

[0094] Example 4

[0095] In this example, the tungsten polishing rate and line indentation (recession) of nine polishing compositions were evaluated. This example demonstrates the effect of cationic polyamino acids on indentation during tungsten CMP operations. CMP compositions were obtained using a procedure similar to that described above with respect to Example 1 (where concentrated colloidal silica was added to a mixture comprising malonic acid and ferric nitrate). Each of the polishing compositions comprised 445 ppm (by weight) malonic acid, 206 ppm (by weight) ferric nitrate nonhydrate (Fe(NO3)3·9H2O), 0.33 wt% cationic aminosilane-treated colloidal silica (prepared as disclosed in U.S. Patents 7,994,057 and 9,028,572), 15 ppm (by weight) Kathon LX, and 2.0 wt% hydrogen peroxide at pH 2.3 (pH adjusted using nitric acid). The treated colloidal silica had an average particle size of 120 nm.

[0096] The polishing composition for reference C does not contain any other components. The polishing composition for reference E includes 500 ppm (by weight) of L-lysine. Other polishing compositions contain polymers (or inhibitors) whose dosages are adjusted so that all compounds are present in equimolar monomeric amounts. The polishing composition for reference F includes 8.6 ppm (by weight) of α-poly-L-aspartic acid. The polishing composition for reference G includes 9.3 ppm (by weight) of α-poly-L-glutamic acid.

[0097] Polishing compositions 4A-4E comprise 10 ppm (by weight) of ε-poly-L-lysine (4A), 10 ppm (by weight) of α-poly-D-lysine (4B), 11.5 ppm (by weight) of α-poly-L-arginine hydrochloride (4C), 10 ppm (by weight) of α-poly-L-lysine hydrochloride with a concentration of 4700 Daltons per MW (4D), and 12.5 ppm (by weight) of α-poly-L-lysine hydrobromide with a concentration of 66,000 DaMW (4E), respectively. Table 5 shows the polyamino acid pK of controls F, controls G, and compositions 4A to 4E. a Values. These values ​​are obtained from Table 1. It is assumed that the values ​​of compositions 4B and 4E are the same as the values ​​of composition 4D given in Table 1.

[0098] Tungsten polishing rates are achieved using a polishing blanket-coated tungsten wafer. Line recess values ​​are obtained by polishing a 2k Silyb 854 tungsten patterned wafer (available from Silyb Wafer Services) with a titanium nitride barrier layer. The process is carried out at a downforce of 2.0 psi, a platen speed of 115 rpm, and a head speed of 121 rpm. CMP polishing tools and The E6088 polishing pad was used to polish the wafers. The slurry flow rate was 90 ml / min. Each patterned wafer was polished to the optical endpoint with an additional 30% overpolishing. The indentation of the lines was measured using an atomic force microscope (AFM) surface profilometer, spanning a 1×1 micrometer line feature. The tungsten polishing rate and the indentation values ​​of the lines are shown in Table 5.

[0099] Table 5

[0100]

[0101] Note: The typical measurement uncertainty for W-shaped concavity is...

[0102] As clearly shown in the results listed in Table 5, compared with the example without inhibitor (control C), using pK a Non-cationic polyamino acids with a molecular weight <5 (controls F&G) did not significantly reduce the indentation of the tungsten wire. Meanwhile, the non-polymeric amino acid L-lysine (control E) reduced the indentation of the wire to the same extent as polishing compositions 4B-4E, with an observed reduction in tungsten removal rate of over 50%. Compared to control E, and unlike control C which showed no corresponding reduction in tungsten polishing rate, polishing compositions 4A to 4E achieved a significant reduction in wire indentation. In the preferred embodiment, the use of ε-poly-L-lysine resulted in tungsten protrusions (negative indentation), a highly desirable characteristic for many integration schemes. Comparisons of Examples 4B, 4D, and 4E further demonstrate that changes in polymer molecular weight and stereochemistry do not significantly affect tungsten CMP performance.

[0103] Example 5

[0104] In this example, the tungsten polishing rate and line indentation (recession) of five polishing compositions were evaluated. This example demonstrates the effect of ε-poly-L-lysine concentration on tungsten polishing rate and indentation during tungsten CMP operation. CMP compositions were obtained using a procedure similar to that described above with respect to Example 1 (where concentrated colloidal silica was added to a mixture comprising malonic acid and ferric nitrate). Each of the polishing compositions comprised 445 ppm (by weight) of malonic acid, 206 ppm (by weight) of ferric nitrate nonahydrate (Fe(NO3)3·9H2O), 0.33 wt% of cationic aminosilane-treated colloidal silica (prepared as disclosed in U.S. Patents 7,994,057 and 9,028,572), 15 ppm (by weight) of Kathon LX, and 2.0 wt% of hydrogen peroxide at pH 2.3 (pH adjusted using nitric acid). The treated colloidal silica had an average particle size of 120 nm. The polishing composition of control C does not contain any other components (i.e., it does not contain ε-poly-L-lysine). As indicated in Table 6, polishing compositions 5A-5D contain 12 ppm (5A), 25 ppm (5B), 50 ppm (5C), and 75 ppm (5D) of ε-poly-L-lysine.

[0105] Tungsten polishing rates are achieved using a polishing blanket-coated tungsten wafer. Line recess values ​​are obtained by polishing a 2k Silyb 854 tungsten patterned wafer (available from Silyb Wafer Services) with a titanium nitride barrier layer. The process is carried out at a downforce of 2.0 psi, a platen speed of 115 rpm, and a head speed of 121 rpm. CMP polishing tools and The E6088 polishing pad was used to polish the wafers. The slurry flow rate was 90 ml / min. Each patterned wafer was polished to the optical endpoint with an additional 30% overpolishing. The indentation of the line was measured using an atomic force microscope (AFM) surface profilometer across a 1×1 micrometer line feature. The tungsten polishing rate and the indentation values ​​of the line are shown in Table 6.

[0106] Table 6

[0107]

[0108] As clearly shown in the results listed in Table 6, the addition of ε-poly-L-lysine significantly reduces the indentation of the tungsten wire. In this particular exemplary formulation, compositions having an ε-poly-L-lysine concentration of less than or equal to 25 ppm are preferred.

[0109] Example 6

[0110] This embodiment evaluates the polishing rates, line erosion, and line indentation (recession) of two polishing compositions for tungsten, TEOS, and patterned field oxide. This embodiment demonstrates the effect of ε-poly-L-lysine on reducing line erosion during tungsten polishing CMP operations. Each of the two polishing compositions comprises 100 ppm (by weight) malonic acid, 54 ppm (by weight) ferric nitrate nonhydrate (Fe(NO3)3·9H2O), 2 wt% cationic colloidal silica (prepared as disclosed in Example 13 of commonly assigned U.S. Patent 9,422,456), 15 ppm (by weight) Kathon LX, and 0.80 wt% hydrogen peroxide at pH 4.4 (pH adjusted using nitric acid). Polishing composition 7A also contains an additional 1600 ppm glycine, while polishing composition 7B contains an additional 25 ppm ε-poly-L-lysine.

[0111] Tungsten and TEOS polishing rates are achieved by using a polishing blanket-coated tungsten and TEOS wafer. This is achieved using AppliedMaterials 200mm... Polishing tools and E6088 polishing pads were used to polish 2k Silyb 854 tungsten patterned wafers to obtain pattern oxide field removal rate, etch value, and line recess values. The Silyb 854 tungsten patterned wafers were pre-polished (prepared) using commercially available W8051 (2% H2O2) bulk slurry from Cabot Microelectronics. Tungsten polishing conditions were as follows: downforce = 2.5 psi, platen speed = 100 rpm, head speed = 101 rpm, and slurry flow rate = 50 ml / min. The pattern polishing times shown in Table 7 are based on the time taken to polish the pattern. The removal rate of TEOS targeted at the blanket-covered TEOS was determined. Atomic force microscopy (AFM) surface profilometry was used to measure the erosion and indentation values ​​across a 3 × 1 μm line feature. Polishing results for the blanket and pattern are presented in Table 7.

[0112] Table 7

[0113]

[0114] As the results listed in Table 7 clearly demonstrate, the addition of ε-poly-L-lysine significantly reduces oxide erosion while maintaining a highly favorable line protrusion.

[0115] All references cited in this article (including publications, patent applications and patents) are incorporated herein by reference as if each reference were individually and specifically cited for reference and as fully described herein.

[0116] The terms “a,” “an,” and “the,” and similar designations used in describing the scope of the invention (particularly the scope of the appended claims) should be understood to include both singular and plural forms unless otherwise stated herein or the context clearly contradicts them. The terms “comprising,” “having,” “including,” and “containing” should be understood as open-ended terms (i.e., meaning “including, but not limited to”) unless otherwise stated. The enumeration of numerical ranges herein is merely a shorthand method of individually referring to each independent value falling within that range, unless otherwise stated herein, and each independent value is introduced in the specification as if it were individually enumerated herein. All methods described herein can be performed in any suitable order unless otherwise stated herein or clearly contradicted by the context. The use of any and all instances or exemplary language (e.g., “for example, such as”) provided herein is merely for better illustrating the invention and not for limiting the scope of the invention, unless otherwise stated. No language in the specification should be construed as necessary to indicate any non-claimed element as essential to the practice of the invention.

[0117] Preferred embodiments of the invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors encourage those skilled in the art to adopt such variations appropriately, and the inventors encourage the invention to be practiced in ways different from those specifically described herein. Therefore, the invention includes all modifications and equivalents of the subject matter listed in the appended claims as permitted by applicable law. Furthermore, the invention covers any combination of the foregoing elements in all possible variations, unless otherwise stated herein or clearly contradicted by the context.

Claims

1. A chemical mechanical polishing composition, comprising: a water-based liquid carrier; abrasive particles dispersed in the liquid carrier, an iron-containing promoter; and a cationic polymer having amino acid monomer units, wherein the abrasive particles comprise colloidal silica abrasive having a permanent positive charge of at least 10 mV; and wherein the cationic polymer has an acid dissociation constant greater than 5 ), and wherein the cationic polymer is - poly-L-lysine.

2. The composition of claim 1, wherein the iron-containing promoter comprises a dissolvable iron-containing catalyst.

3. The composition of claim 2, further comprising a stabilizing agent bound to the dissolvable iron-containing catalyst, the stabilizing agent selected from the group consisting of phosphoric acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, and mixtures thereof.

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

5. The composition of claim 1, having a pH in the range of 1.0 to 5.

0.

6. The composition of claim 1, wherein the cationic polymer has an acid dissociation constant (pKa) of from 6 to 11. ) 7. The composition of claim 1, comprising 1 to 200 ppm by weight of the cationic polymer.

8. The composition of claim 1, comprising 5 to 50 ppm by weight of the cationic polymer.

9. The composition of claim 1, wherein the cationic polymer has a molecular weight in the range of 1 to 100 kDa.

10. A chemical mechanical polishing composition, comprising: a water-based liquid carrier; colloidal silica abrasive particles dispersed in the liquid carrier, a dissolvable iron-containing catalyst; a stabilizing agent bound to the dissolvable iron-containing catalyst; Cationic polymers having amino acid monomer units, the cationic polymers being - poly-L-lysine; and wherein the composition has a pH in the range of 1 to 5, wherein the colloidal silica abrasive particles have a permanent positive charge of at least 10 mV; and wherein the cationic polymer has an acid dissociation constant greater than 5 ).

11. A method of chemical mechanical polishing a substrate comprising a tungsten layer, the method comprising: (a) contacting the substrate with a polishing composition comprising: (i) a water-based liquid carrier; (ii) abrasive particles dispersed in the liquid carrier; (iii) an iron-containing promoter; and (iv) a cationic polymer having amino acid monomer units, wherein the abrasive particles comprise colloidal silicon dioxide abrasive having a permanent positive charge of at least 10 mV; and wherein the cationic polymer has an acid dissociation constant greater than 5 ); and wherein the cationic polymer is - poly-L-lysine (b) moving the polishing composition relative to the substrate; and (c) abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.

12. The method of claim 11, wherein: (i) the iron-containing promoter comprises a dissolvable iron-containing catalyst; and (ii) the polishing composition further comprises a stabilizing agent bound to the dissolvable iron-containing catalyst, the stabilizing agent selected from a group consisting of phosphoric acid, phthalic acid, citric acid, adipic acid, 13. The method of claim 11, wherein: (i) the polishing composition further comprises a hydrogen peroxide oxidizing agent; and (ii) the polishing composition has a pH in the range of 1.0 to 5.

0.

14. The method of claim 11, comprising 1 to 200 ppm by weight of the cationic polymer.

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