Silica-based slurry for selective polishing of carbon-based films

Abstract

This invention provides a chemical-mechanical polishing composition comprising: (a) a silicon dioxide abrasive, (b) iron cations, (c) ligands, (d) a cationic polymer, (e) a nonionic polymer (if applicable), and (f) water. This invention also provides a method for chemically-mechanically polishing substrates, particularly carbon-based thin films, using this composition.

Description

[Previous Technology]

[0001] In the fabrication of integrated circuits and other electronic devices, multiple layers of conductive, semiconductive, and dielectric materials are deposited on or removed from the surface of a substrate. As the layers of material are successively deposited on and removed from the substrate, the uppermost surface of the substrate may become uneven and requires planarization. Planarization, or "polishing," is a process in which material is removed from the surface of the substrate to form a generally smooth, flat surface. Planarization can be used to remove undesirable surface shapes and defects, such as rough surfaces, agglomerated materials, lattice damage, scratches, and contaminated layers or materials. Planarization can also be used to form such features on a substrate by removing excess deposited material used to fill features and provide a smooth surface for subsequent metallization and processing levels.

[0002] Compositions and methods for planarizing or polishing substrate surfaces are well known in the industry. Chemical-mechanical planarization or chemical-mechanical polishing (CMP) is a common technique for planarizing substrates. CMP utilizes a chemical composition (referred to as a CMP composition or more simply as a polishing composition (also known as a polishing slurry)) for the selective removal of material from the substrate. The polishing composition is typically applied to the substrate by bringing the substrate surface into contact with a polishing pad (e.g., a polishing cloth or polishing disc) saturated with the polishing composition. The polishing of the substrate is typically further aided by the chemical activity of the polishing composition and / or the mechanical activity of abrasives suspended in or incorporated into the polishing composition (e.g., a fixed abrasive polishing pad).

[0003] Polishing compositions can be characterized by their polishing rate (i.e., removal rate) and planarization efficiency. Polishing rate refers to the rate at which material is removed from the substrate surface and is typically expressed in length (thickness) units / time units (e.g., angstroms (Å) / minute). Planarization efficiency is related to the step height reduction or the amount of material removed from the substrate. Specifically, the polishing surface (e.g., a polishing pad) first contacts the "high point" of the surface and material must be removed to form a planar surface. Processes that result in a planar surface with less material removal are considered more efficient than processes that require more material removal to achieve planarization.

[0004] As the size of integrated circuits (ICs) decreases and the number of ICs on a chip increases, the components constituting the circuits must be positioned more closely together to fit the limited space available on a typical chip. Effective separation between circuits is crucial for ensuring optimal semiconductor performance. To this end, shallow trenches are etched into the semiconductor substrate and filled with an insulating material to separate the functional areas of the ICs. More specifically, shallow trench separation (STI) is a process in which a silicon nitride or titanium nitride layer is formed on a silicon substrate, shallow trenches are formed by etching or photolithography, and a dielectric layer is deposited to fill the trenches. Because the trench depths formed in this way vary, excess dielectric material is typically deposited on top of the substrate to ensure complete filling of all trenches. The dielectric material (e.g., a carbon-based thin film) conforms to the underlying topography of the substrate. Excess dielectric material is typically removed by a CMP process, which additionally provides a flat surface for further processing.

[0005] Carbon-based thin films have recently emerged as hard masking materials for faster switching in semiconductor applications, such as 3D-NAND flash memory. Typically, due to the strong sp2 and sp3 carbon-carbon bonds, the removal rate of carbon-based thin films (e.g., amorphous carbon and spin-coated carbon) can be a limiting factor for the electropolishing step in the STI process, thus a high removal rate of carbon-based thin films is desired to increase device throughput. However, if the capping layer removal rate is too rapid, over-polishing of the exposed oxides in the trenches leads to trench erosion and an increased device defect rate.

[0006] Conventional methods for removing carbon-based films include the use of polishing compositions containing strong chemical oxidants (such as potassium permanganate and cerium ammonium nitrate). However, such strong chemical oxidants can cause hazardous materials to be disposed of and / or produce undesirable residues on the polished surface.

[0007] Therefore, there remains a need for compositions and methods for the chemical-mechanical polishing of carbon-based thin films, which would provide a useful removal rate while reducing undesirable residues on the polished surface. The present invention provides such polishing compositions and methods. These and other advantages and features of the invention will become apparent from the description of the invention provided herein. [Summary of the Invention]

[0008] The present invention provides a chemical-mechanical polishing composition comprising: (a) a silicon dioxide abrasive, (b) iron cations, (c) ligands, (d) a cationic polymer, (e) a nonionic polymer as appropriate, and (f) water.

[0009] The present invention further provides a method for chemically-mechanically polishing a substrate, comprising: (i) providing a substrate, (ii) providing a polishing pad, (iii) providing a chemically-mechanically polishing composition comprising: (a) a silicon dioxide abrasive, (b) iron cations, (c) ligands, (d) a cationic polymer and (e) water, (iv) contacting the substrate with the polishing pad and the chemically-mechanically polishing composition, and (v) moving the polishing pad and the chemically-mechanically polishing composition relative to the substrate to abrade at least a portion of the substrate to polish the substrate.

Implementation Method

[0013] The present invention provides a chemical-mechanical polishing composition comprising: (a) a silicon dioxide abrasive, (b) iron cations, (c) ligands, (d) a cationic polymer, (e) a nonionic polymer as appropriate, and (f) water.

[0014] The chemical-mechanical polishing composition includes silica abrasive. As used herein, the terms "silica abrasive," "silica abrasive particles," "silica particles," and "abrasive particles" are used interchangeably and can refer to any silica particles. Silica particles can be modified (e.g., surface-modified) or unmodified and have a negative natural zeta potential, a positive natural zeta potential, or a approximately neutral natural zeta potential. As used herein, the phrase "natural zeta potential" refers to the zeta potential of the silica abrasive before it is added to the polishing composition. For example, natural zeta potential can refer to the zeta potential of the silica abrasive before it is added to the polishing composition, such as when measured in a storage dispersion or an aqueous dispersion. Those skilled in the art should be able to determine whether the silica abrasive has a negative or positive natural zeta potential before it is added to the polishing composition.

[0015] The charge on dispersed particles (e.g., silica abrasives) is commonly referred to as the zeta potential (or zeta potential). The zeta potential of a particle refers to the potential difference between the charge of ions surrounding the particle and the charge of the bulk solution of the measured composition (e.g., liquid carrier and any other components dissolved therein). The zeta potential typically 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 away from the isoelectric point, the surface charge (and therefore the zeta potential) increases or decreases accordingly (to negative or positive zeta potential values). The native zeta potential and zeta potential of the polishing composition can be obtained using a DT-1202 acoustic and electroacoustic spectrometer available from Dispersion Technologies, Inc. (Bedford Hills, NY) or a Malvern Zetasizer available from Malvern Panalytical (Malvern, United Kingdom) using electrophoretic light scattering.

[0016] In some embodiments, the silicon dioxide abrasive has a positive zeta potential. As used herein, the phrase "positive zeta potential" refers to a silicon dioxide abrasive exhibiting a positive surface charge when measured in a polishing composition. In some embodiments, the silicon dioxide abrasive has a zeta potential greater than 0 mV when measured in a polishing composition, i.e., the silicon dioxide abrasive has a positive zeta potential when measured in a polishing composition. For example, the silicon dioxide abrasive may have a zeta potential of 10 mV or higher in a chemical-mechanical polishing composition, a zeta potential of 20 mV or higher in a chemical-mechanical polishing composition, a zeta potential of 30 mV or higher in a chemical-mechanical polishing composition, or a zeta potential of 40 mV or higher in a chemical-mechanical polishing composition. In some embodiments, the silicon dioxide abrasive has a positive zeta potential of about 0 mV to about 60 mV, for example, about 10 mV to about 60 mV, about 10 mV to about 50 mV, about 10 mV to about 40 mV, about 20 mV to about 60 mV, about 20 mV to about 50 mV, about 20 mV to about 40 mV, about 30 mV to about 40 mV, about 20 mV to about 30 mV, about 30 mV to about 60 mV, about 30 mV to about 50 mV, or about 30 mV to about 40 mV.

[0017] Silica particles (e.g., colloidal silica particles) and charged silica particles (e.g., colloidal silica particles) can be prepared by various methods, some examples of which are commercially used and known. Useful silica particles comprise precipitated or condensed silica, which can be prepared using known methods, such as by a method known as a "sol-gel" method or by silicate ion exchange. Condensed silica particles are typically prepared by condensing Si(OH)4 to form substantially spherical (e.g., spherical, oval, or rectangular) particles. The precursor Si(OH)4 can be obtained, for example, by hydrolyzing a high-purity alkoxysilane or acidifying an aqueous silicate solution. U.S. Patent No. 5,230,833 describes a method for preparing colloidal silica particles in solution.

[0018] In some embodiments, the silica abrasive is colloidal silica. As is known to those skilled in the art, colloidal silica is a suspension of fine amorphous, non-porous, and generally spherical particles in a liquid phase. Colloidal silica can be in the form of condensed or precipitated silica particles. In some embodiments, the silica is in the form of wet-process silica particles. The particles (e.g., colloidal silica) can have any suitable average size (i.e., average particle size). If the average abrasive particle size is too small, the polishing composition cannot exhibit a sufficient removal rate. Conversely, if the average abrasive particle size is too large, the polishing composition may exhibit undesirable polishing performance (e.g., poor substrate defect rate).

[0019] Therefore, silicon dioxide abrasives may have an average particle size of about 10 nm or greater, such as about 15 nm or greater, about 20 nm or greater, about 25 nm or greater, about 30 nm or greater, about 35 nm or greater, about 40 nm or greater, about 45 nm or greater, about 50 nm or greater, about 60 nm or greater, about 70 nm or greater, about 80 nm or greater, about 90 nm or greater, or about 100 nm or greater. Alternatively or additionally, silicon dioxide abrasives may have an average particle size of about 200 nm or less, such as about 175 nm or less, about 150 nm or less, about 125 nm or less, about 110 nm or less, about 100 nm or less, about 90 nm or less, about 80 nm or less, about 75 nm or less, about 50 nm or less, or about 40 nm or less. Therefore, silicon dioxide abrasives can have an average particle size defined by any two of the endpoints mentioned above.

[0020] For example, silicon dioxide abrasives may have the following structures: about 10 nm to about 200 nm, about 20 nm to about 200 nm, about 20 nm to about 175 nm, about 20 nm to about 150 nm, about 20 nm to about 125 nm, about 20 nm to about 110 nm, about 20 nm to about 100 nm, about 25 nm to about 125 nm, about 25 nm to about 110 nm, about 25 nm to about 100 nm, about 30 nm to about 100 nm, about 30 nm to about 75 nm, about 30 nm to about 40 nm, about 50 nm to about 150 nm, about 50 nm to about 125 nm, about 50 nm to about 110 nm, about 50 nm to about 100 nm, about 80 nm to about 150 nm, about 80 nm to about 125 nm, about 80 nm to about 110 nm, about 80 nm to about 100 nm, about 90 nm to about 150 nm, about 90 nm to about 125 nm. The average particle size is approximately 90 nm to approximately 110 nm, approximately 90 nm to approximately 100 nm, approximately 100 nm to approximately 150 nm, or approximately 100 nm to approximately 125 nm. In some embodiments, the silica abrasive has an average particle size of approximately 90 nm to approximately 150 nm. In some embodiments, the silica abrasive has an average particle size of approximately 90 nm to approximately 125 nm. In some embodiments, the silica abrasive has an average particle size of approximately 90 nm to approximately 110 nm. In some embodiments, the silica abrasive has an average particle size of approximately 100 nm to approximately 125 nm. For non-spherical silica abrasive particles, the particle size is the diameter of the smallest sphere surrounding the particle. Any suitable technique can be used to measure the abrasive particle size, such as laser diffraction. Suitable particle size measuring instruments are available from, for example, Malvern Instruments (Malvern, UK).

[0021] Silica abrasives preferably exhibit colloidal stability in polishing compositions. The term colloidal refers to a suspension of particles in a liquid carrier (e.g., water). Colloidal stability refers to the ability to maintain this suspension form over a period of time. In the context of this invention, an abrasive is considered to have colloidal stability if, when the abrasive is placed in a 100 mL graduated cylinder and left to stand undisturbed for 2 hours, the difference between the particle concentration ([B], in g / mL) in the bottom 50 mL of the graduated cylinder and the particle concentration ([T], in g / mL) in the top 50 mL of the graduated cylinder, divided by the initial particle concentration ([C], in g / mL) in the abrasive composition, is less than or equal to 0.5 (i.e., {[B] – [T]} / [C] ≤ 0.5). More preferably, the value of [B]-[T] / [C] is less than or equal to 0.3, and most preferably less than or equal to 0.1.

[0022] Silica abrasives may be present in the polishing composition in any suitable amount. If the polishing composition of the present invention contains too little abrasive, the composition may not exhibit a sufficient removal rate. Conversely, if the polishing composition contains too much abrasive, the polishing composition may exhibit undesirable polishing performance and / or may not be cost-effective and / or may lack stability. The polishing composition may include about 10 wt.% or less of silicon dioxide abrasive, such as about 9 wt.% or less, about 8 wt.% or less, about 7 wt.% or less, about 6 wt.% or less, about 5 wt.% or less, about 4 wt.% or less, about 3 wt.% or less, about 2 wt.% or less, about 1 wt.% or less, about 0.9 wt.% or less, about 0.8 wt.% or less, about 0.7 wt.% or less, about 0.6 wt.% or less, or about 0.5 wt.% or less of silicon dioxide abrasive. Alternatively or additionally, the polishing composition may include about 0.001 wt.% or more of silicon dioxide abrasive, such as about 0.005 wt.% or more, about 0.01 wt.% or more, 0.05 wt.% or more, about 0.1 wt.% or more, about 0.2 wt.% or more, about 0.3 wt.% or more, about 0.4 wt.% or more, about 0.5 wt.% or more, or about 1 wt.% or more of silicon dioxide abrasive. Therefore, if appropriate, the polishing composition may include an amount of silicon dioxide abrasive defined by any two of the endpoints mentioned above.

[0023] For example, in some embodiments, the silicon dioxide abrasive may be present in the polishing composition in an amount of about 0.001 wt.% to about 10 wt.%, such as about 0.001 wt.% to about 8 wt.%, about 0.001 wt.% to about 6 wt.%, about 0.001 wt.% to about 5 wt.%, about 0.001 wt.% to about 4 wt.%, about 0.001 wt.% to about 2 wt.%, about 0.001 wt.% to about 1 wt.%, about 0.01 wt.% to about 10 wt.%, about 0.01 wt.% to about 8 wt.%, about 0.01 wt.% to about 6 wt.%, about 0.01 wt.% to about 5 wt.%, about 0.01 wt.% to about 4 wt.%, about 0.01 wt.% to about 2 wt.%, about 0.01 wt.% to about 1 wt.%. wt.%, about 0.05 wt.% to about 10 wt.%, about 0.05 wt.% to about 8 wt.%, about 0.05 wt.% to about 6 wt.%, about 0.05 wt.% to about 5 wt.%, about 0.05 wt.% to about 4 wt.%, about 0.05 wt.% to about 2 wt.%, about 0.05 wt.% to about 1 wt.%, about 0.1 wt.% to about 10 wt.%, about 0.1 wt.% to about 8 wt.%, about 0.1 wt.% to about 6 wt.%, about 0.1 wt.% to about 5 wt.%, about 0.1 wt.% to about 4 wt.%, about 0.1 wt.% to about 2 wt.%, about 0.1 wt.% to about 1 wt.%, about 0.5 wt.% to about 10 wt.%, about 0.5 wt.% to about 8 wt.%, about 0.5 wt.% to about 5 wt.%, about 0.5 wt.% to about 4 wt.%, about 0.5 wt.% to about 2 wt.%, about 0.5 wt.% to about 1 wt.%, about 1 wt.% to about 10 wt.%, about 1 wt.% to about 8 wt.%, about 1 wt.% to about 6 wt.%, about 1 wt.% to about 5 wt.%, about 1 wt.% to about 4 wt.%, or about 1 wt.% to about 2 wt.%. In some embodiments, the polishing composition comprises about 0.001 wt.% to about 10 wt.% of silicon dioxide abrasive. In some embodiments, the polishing composition comprises about 0.05 wt.% to about 5 wt.% of silicon dioxide abrasive.

[0024] The chemical-mechanical polishing composition includes iron cations. The iron cations may be ferric (i.e., iron III) or ferrous (i.e., iron II) and may be added to the composition as any suitable iron-containing salt. For example, iron cations may be generated by adding ferric nitrate, ferric sulfate, ferric halides (including ferric fluoride, ferric chloride, ferric bromide and ferric iodide, as well as ferric perchlorate, ferric perbromate and ferric periolate) and organic iron compounds (e.g., ferric acetate, ferric acetone, ferric citrate, ferric gluconate, ferric malonate, ferric oxalate, ferric phthalate, ferric succinate, and combinations thereof) to the polishing composition.

[0025] The polishing composition may include any suitable amount of iron cations. The polishing composition may include about 0.01 ppm or more of iron cations, such as 0.1 ppm or more, about 0.5 ppm or more, about 1 ppm or more, about 5 ppm or more, about 10 ppm or more, about 20 ppm or more, about 50 ppm or more, or about 100 ppm or more. Alternatively or additionally, the polishing composition may include about 1000 ppm or less of iron cations, such as about 900 ppm or less, about 800 ppm or less, about 700 ppm or less, about 600 ppm or less, about 500 ppm or less, about 400 ppm or less, about 300 ppm or less, about 200 ppm or less, about 100 ppm or less, about 80 ppm or less, about 60 ppm or less, or about 40 ppm or less. Thus, the polishing composition may include an amount of iron cations defined by any two of the foregoing endpoints. For example, the polishing composition may include iron cations from about 0.01 ppm to about 1000 ppm, such as iron cations from about 0.01 ppm to about 500 ppm, iron cations from about 0.01 ppm to about 100 ppm, iron cations from about 0.01 ppm to about 80 ppm, iron cations from about 0.01 ppm to about 60 ppm, iron cations from about 0.01 ppm to about 40 ppm, iron cations from about 0.1 ppm to about 100 ppm, iron cations from about 0.1 ppm to about 80 ppm, iron cations from about 0.1 ppm to about 60 ppm, iron cations from about 0.1 ppm to about 40 ppm, iron cations from about 1 ppm to about 1000 ppm, iron cations from about 1 ppm to about 500 ppm, iron cations from about 10 ppm to about 1 ... ppm, about 10 ppm to about 80 ppm, about 10 ppm to about 60 ppm, about 10 ppm to about 40 ppm, about 50 ppm to about 1000 ppm, about 50 ppm to about 500 ppm, about 50 ppm to about 100 ppm, about 50 ppm to about 80 ppm, about 100 ppm to about 1000 ppm or about 100 ppm to about 500 ppm.

[0026] Without being limited to any particular theory, it is believed that increased iron concentration results in a higher removal rate of carbon-based films. However, it is also believed that a higher iron concentration may be associated with a variety of defect problems when polishing commercially available carbon-based films. In some embodiments, iron cations are present in the polishing composition in an amount from about 1 ppm to about 1000 ppm based on the total weight of the polishing composition. In some embodiments, iron cations are present in the polishing composition in an amount from about 10 ppm to about 500 ppm based on the total weight of the polishing composition.

[0027] The chemimechanical polishing composition includes a ligand (e.g., a ligand for an iron cation). The ligand can be any suitable ligand, many of which are known in the art. In some embodiments, the ligand includes an olefin moiety, an alkyne moiety, a diacid moiety, an alcohol moiety, or a combination thereof. For example, the ligand can be any compound (e.g., an organic compound) including an olefin moiety; an alkyne moiety; a diacid moiety; an alcohol moiety; an olefin moiety and a diacid moiety; an olefin moiety and an alcohol moiety; an olefin moiety, a diacid moiety and an alcohol moiety; an alkyne moiety, a diacid moiety and an alcohol moiety; or an olefin moiety, an alkyne moiety, a diacid moiety and an alcohol moiety; or an olefin moiety, an alkyne moiety, a diacid moiety and an alcohol moiety. In some embodiments, the ligand includes an olefin moiety and a diacid moiety; or an alkyne moiety and an alcohol moiety.

[0028] Example ligands include (but are not limited to) 3,5-dimethyl-1-hexyn-3-ol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol ethoxylate, 2,5-dimethyl-3-hexyn-2,5-diol, 3-methyl-1-pentyn-3-ol, phosphoric acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, fumaric acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, maleic acid, penteneic acid, mucoconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, tartaric acid, their salts, and combinations thereof. In some embodiments, the formulation comprises phosphoric acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, fumaric acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, maleic acid, penteneic acid, mucoconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, tartaric acid, their salts, or combinations thereof. In some embodiments, the formulation comprises malonic acid or its salts.

[0029] The polishing composition may include any suitable amount of ligand. For example, the polishing composition may include about 10 ppm or more of ligand, such as about 15 ppm or more, about 20 ppm or more, about 25 ppm or more, about 30 ppm or more, about 35 ppm or more, or about 40 ppm or more. Alternatively or additionally, the polishing composition may include about 1000 ppm or less of ligand, such as about 800 ppm or less, about 600 ppm or less, about 400 ppm or less, about 200 ppm or less, about 100 ppm or less, about 80 ppm or less, about 60 ppm or less, or about 40 ppm or less. Thus, the polishing composition may include ligands in amounts defined by any two of the endpoints mentioned above. For example, the polishing composition may include ligands of about 10 ppm to about 1000 ppm, such as about 10 ppm to about 800 ppm, about 10 ppm to about 600 ppm, about 10 ppm to about 400 ppm, about 10 ppm to about 200 ppm, about 10 ppm to about 100 ppm, about 10 ppm to about 80 ppm, about 10 ppm to about 60 ppm, about 10 ppm to about 40 ppm, about 20 ppm to about 1000 ppm of the surfactant, about 20 ppm to about 800 ppm, about 20 ppm to about 600 ppm, about 20 ppm to about 400 ppm, about 20 ppm to about 200 ppm, about 20 ppm to about 100 ppm, about 20 ppm to about 80 ppm, about 20 ppm to about 60 ppm, or about 20 ppm to about 40 ppm.

[0030] The iron cation and ligand may be present in the polishing composition in any suitable molar ratio. However, typically, the ligand is present in molar excess relative to the iron cation. In some embodiments, the iron cation and ligand are present in the composition in a molar ratio of 1:1 to 1:5, such as 1:1 to 1:4, 1:1 to 1:3, 1:1 to 1:2, 4:5 to 1:5, 4:5 to 1:4, 4:5 to 1:3, 4:5 to 1:2, 2:3 to 1:5, 2:3 to 1:4, 2:3 to 1:3, or 2:3 to 1:2. In some embodiments, the iron cation and ligand are present in the composition in a molar ratio of 1:1 to 1:5. In some embodiments, the iron cation and ligand are present in the composition in a molar ratio of 1:1 to 1:3. In some embodiments, the iron cation and ligand are present in the composition in a molar ratio of about 1:2.

[0031] The chemical-mechanical polishing composition includes a cationic polymer. The cationic polymer may include any suitable cationic monomer capable of undergoing free radical polymerization and / or addition polymerization. In some embodiments, the cationic polymer includes a cationic monomer selected from the following: N-vinylimidazolium, 2-(dimethylamino)ethyl acrylate (“DMAEA”), 2-(dimethylamino)ethyl methacrylate (“DMAEM”), 3-(dimethylamino)propylmethacrylamide (“DMAPMA”), 3-(dimethylamino)propylacrylamide (“DMAPA”), 3-methacrylaminopropyltrimethylammonium chloride (“MAPTAC”), 3-acrylaminopropyltrimethylammonium chloride (“MAPTAC”). Ammonium chloride (“APTAC”), diallyl dimethyl ammonium chloride (“DADMAC”), 2-(acryloxy)-N,N,N-trimethylethane ammonium chloride (“DMAEA.MCQ”), 2-(methacryloxy)-N,N,N-trimethylethane ammonium chloride (“DMAEM.MCQ”), N,N-dimethylaminoethyl acrylate benzyl chloride (“DMAEA.BCQ”), N,N-dimethylaminoethyl methacrylate benzyl chloride (“DMAEM.BCQ”), salts thereof, and combinations thereof. It should be understood from the foregoing list that any alternative anionic ions (e.g., bromide, iodide, sulfate, methanesulfonate, and phosphate) are also suitable. Alternatively, the cationic polymer may comprise cationic amino acid monomers. For example, in some embodiments, the cationic polymer comprises arginine, histidine, or lysine. In some embodiments, the cationic polymer is polylysine. It should be understood that polylysine may include ε-polylysine and / or α-polylysine composed of D-lysine and / or L-lysine. Polylysine may thus include α-poly-L-lysine, α-poly-D-lysine, ε-poly-L-lysine, ε-poly-D-lysine, their salts, and mixtures thereof.

[0032] Example cationic polymers include (but are not limited to) poly(vinylimidazolium), poly(methacryloxyethyltrimethylammonium chloride) (polyMADQUAT), poly(diallyldimethylammonium chloride) (polyDADMAC) (e.g., polytetramethylammonium salt-6), poly(dimethylamine-co-epimercohydrin), and poly[bis(2-chloroethyl)ether-alternating-1,3-bis[3-(dimethylamino)propyl]urea] (e.g., polyquaternary ammonium salt-2), copolymers of hydroxyethyl cellulose and diallyl dimethyl ammonium (e.g., polyquaternary ammonium salt-4), copolymers of acrylamide and diallyl dimethyl ammonium (e.g., polyquaternary ammonium salt-7), ethoxylated hydroxyethyl cellulose quaternary ammonium (e.g., polyquaternary ammonium salt-10), copolymers of vinylpyrrolidone and dimethylaminoethyl methacrylate quaternary ammonium (e.g., polyquaternary ammonium salt-11), copolymers of vinylpyrrolidone and vinylimidazole quaternary ammonium (e.g., polyquaternary ammonium salt-16), terpolymers of vinylcaprolactone, vinylpyrrolidone, and vinylimidazole quaternary ammonium (e.g., polyquaternary ammonium salt-46), copolymers of methyl sulfate 3-methyl-1-vinylimidazole onium salt-N-vinylpyrrolidone (e.g., polyquaternary ammonium salt-44), copolymers of vinylpyrrolidone and diallyl dimethyl ammonium, Luviquat® Supreme, Luviquat® Hold, Luviquat® UltraCare, Luviquat® FC 370, Luviquat® FC 550, Luviquat® FC 552, Luviquat® Excellence, GOHSEFIMER K210™, GOHSENX K-434, their salts, and combinations thereof. In some embodiments, the cationic polymer system may include poly(vinylimidazolium), polylysine, poly(methacryloxyethyltrimethylammonium chloride) (polyMADQUAT), or poly(diallyldimethylammonium chloride). Poly(dimethylamine-co-epimercohydrin), poly[bis(2-chloroethyl)ether-alternating-1,3-bis[3-(dimethylamino)propyl]urea], copolymers of hydroxyethyl cellulose and diallyl dimethylammonium, copolymers of acrylamide and diallyl dimethylammonium, quaternary ammonium hydroxyethyl cellulose ethoxylate, copolymers of vinylpyrrolidone and quaternary ammonium dimethylaminoethyl methacrylate, copolymers of vinylpyrrolidone and quaternary ammonium vinylimidazole, terpolymers of vinylcaprolactone, vinylpyrrolidone and quaternary ammonium vinylimidazole, methylsulfate 3-methyl-1-vinylimidazole onium salt-N-vinylpyrrolidone copolymer, copolymers of vinylpyrrolidone and diallyl dimethylammonium, salts thereof, or combinations thereof. In some embodiments, the cationic polymer system may include poly(diallyl dimethylammonium chloride) (polyDADMAC) or a salt thereof.

[0033] The polishing composition may include any suitable amount of cationic polymer. The polishing composition may include about 10 ppm or more of cationic polymer, such as about 15 ppm or more, about 20 ppm or more, about 25 ppm or more, about 30 ppm or more, about 35 ppm or more, or about 40 ppm or more. Alternatively or additionally, the polishing composition may include about 1000 ppm or less of cationic polymer, such as about 800 ppm or less, about 600 ppm or less, about 400 ppm or less, about 200 ppm or less, or about 100 ppm or less. Thus, the polishing composition may include an amount of cationic polymer defined by any of the foregoing endpoints. For example, the polishing composition may include a cationic polymer of about 10 ppm to about 1000 ppm, such as about 10 ppm to about 800 ppm, about 10 ppm to about 600 ppm, about 10 ppm to about 400 ppm, about 10 ppm to about 200 ppm, about 10 ppm to about 100 ppm, about 25 ppm to about 1000 ppm, about 25 ppm to about 800 ppm, about 25 ppm to about 600 ppm, about 25 ppm to about 400 ppm, about 25 ppm to about 200 ppm, or about 25 ppm to about 100 ppm.

[0034] Cationic polymers can exist as any suitable structural type. For example, cationic polymers can exist as alternating polymers, random polymers, block polymers, graft polymers, linear polymers, branched polymers, or combinations thereof. Cationic polymers can contain a single monomer unit or any suitable number of different monomer units. For example, cationic polymers can contain 2, 3, 4, 5, or 6 different monomer units. The cationic monomers of the cationic polymer can exist at any suitable concentration and in any suitable proportion.

[0035] The cationic polymer may have any suitable weight-average molecular weight. The cationic polymer may have a weight-average molecular weight of about 150 g / mol or higher, such as about 300 g / mol or higher, about 500 g / mol or higher, about 600 g / mol or higher, about 750 g / mol or higher, about 1000 g / mol or higher, about 1500 g / mol or higher, about 2000 g / mol or higher, about 2500 g / mol or higher, about 3000 g / mol or higher, about 3500 g / mol or higher, about 4000 g / mol or higher, about 4500 g / mol or higher, about 5000 g / mol or higher, about 5500 g / mol or higher, about 6000 g / mol or higher, about 6500 g / mol or higher, about 7000 g / mol or higher, or about 7500 g / mol or higher. Alternatively or additionally, the cationic polymer may have a weight average molecular weight of about 10,000 g / mol or less, such as about 9,000 g / mol or less, about 8,000 g / mol or less, about 7,500 g / mol or less, about 7,000 g / mol or less, about 6,500 g / mol or less, about 6,000 g / mol or less, about 5,500 g / mol or less, about 5,000 g / mol or less, about 4,500 g / mol or less, about 4,000 g / mol or less, about 3,500 g / mol or less, about 3,000 g / mol or less, about 2,500 g / mol or less, or about 2,000 g / mol or less. Therefore, the cationic polymer may have a weight average molecular weight defined by any two of the endpoints mentioned above. For example, the cationic polymer may have a weight average molecular weight of about 150 g / mol to about 10,000 g / mol, such as about 300 g / mol to about 9,000 g / mol, about 500 g / mol to about 8,000 g / mol, about 150 g / mol to about 7,000 g / mol, about 150 g / mol to about 6,000 g / mol, about 150 g / mol to about 5,000 g / mol, about 150 g / mol to about 2,000 g / mol, about 1,000 g / mol to about 10,000 g / mol, about 1,000 g / mol to about 9,000 g / mol, about 1,000 g / mol to about 8,000 g / mol, about 1,000 g / mol to about 7,000 g / mol, about 1,000 g / mol to about 6,000 g / mol, or about 1,000 g / mol to about 5,000 g / mol.

[0036] The chemical-mechanical polishing composition may include one or more compounds capable of adjusting (i.e., regulating) the pH of the polishing composition (i.e., pH adjusting compounds). Any suitable compound capable of adjusting the pH of the polishing composition may be used to adjust the pH of the polishing composition. The pH adjusting compound is preferably water-soluble and compatible with the other components of the polishing composition. Typically, the chemical-mechanical polishing composition has a pH of about 1 to about 7 at the point of use (e.g., about 1 to about 6, about 1 to about 5, about 2 to about 7, about 2 to about 6, about 2 to about 5, about 3 to about 6, or about 1 to about 4). Preferably, the chemical-mechanical polishing composition has a pH of about 1 to about 4 at the point of use.

[0037] The pH of the chemical-mechanical polishing composition may be adjusted using any suitable compound capable of adjusting the pH of the polishing composition. The pH-adjusting compound is preferably water-soluble and compatible with the other components of the polishing composition. Non-limiting examples of suitable acids for adjusting the pH of the polishing composition include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and organic acids (e.g., formic acid and acetic acid). Non-limiting examples of suitable bases for adjusting the pH of the polishing composition include sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

[0038] In some embodiments, the chemical-mechanical polishing composition further comprises one or more additives, such as conditioning agents, acids (e.g., sulfonic acids), chelating agents (e.g., anionic polymeric chelating agents), chelating agents, biocides, scale inhibitors, dispersants, and / or conductivity modifiers. In some embodiments, the polishing composition further comprises a biocide. The biocide (if present) may be any suitable biocide and may be present in any suitable amount in the polishing composition. Suitable biocides are isothiazolinone biocides. Typically, the polishing composition comprises about 1 ppm to about 200 ppm of a biocide (e.g., about 1 ppm to about 100 ppm or about 1 ppm to about 50 ppm), preferably about 10 ppm to about 20 ppm of a biocide.

[0039] In some embodiments, the polishing composition further comprises a nonionic polymer. Thus, in some embodiments, the present invention provides a chemical-mechanical polishing composition comprising (a) a silicon dioxide abrasive, (b) iron cations, (c) ligands, (d) a cationic polymer, (e) a nonionic polymer and (f) water.

[0040] The nonionic polymer may be any suitable polymer that is free of cationic or anionic charge at a pH of about 1 to about 7. In some embodiments, the nonionic polymer is selected from polyalkylene glycols, polyetheramines, polyethylene oxide / polypropylene oxide copolymers, polyacrylamide, polyvinylpyrrolidone, silicate polyalkylene oxide copolymers, hydrophobically modified polyacrylate copolymers, hydrophilic nonionic polymers, polysaccharides, and combinations thereof. In some embodiments, the nonionic polymer is polyvinylpyrrolidone, polyalkylene glycols (e.g., polyethylene glycol (PEG) or polypropylene oxide (PPO)), polyethylene oxide / polypropylene oxide copolymers, or combinations thereof. In a preferred embodiment, the nonionic polymer is polyvinylpyrrolidone.

[0041] Nonionic polymers can exist as any suitable structural type. For example, nonionic polymers can exist as alternating polymers, random polymers, block polymers, graft polymers, linear polymers, branched polymers, or combinations thereof. Nonionic polymers can contain a single monomer unit or any suitable number of different monomer units. For example, nonionic polymers can contain 2, 3, 4, 5, or 6 different monomer units. The nonionic monomers of nonionic polymers can exist at any suitable concentration and in any suitable proportion.

[0042] The nonionic polymer may have any suitable weight-average molecular weight. The nonionic polymer may have a weight-average molecular weight of about 400 g / mol or higher, such as about 500 g / mol or higher, about 600 g / mol or higher, about 750 g / mol or higher, about 1000 g / mol or higher, about 1500 g / mol or higher, about 2000 g / mol or higher, about 2500 g / mol or higher, about 3000 g / mol or higher, about 3500 g / mol or higher, about 4000 g / mol or higher, about 4500 g / mol or higher, about 5000 g / mol or higher, about 5500 g / mol or higher, about 6000 g / mol or higher, about 6500 g / mol or higher, about 7000 g / mol or higher, or about 7500 g / mol or higher. Alternatively or additionally, nonionic polymers may have a weight average molecular weight of about 10,000 g / mol or less, such as about 9,000 g / mol or less, about 8,000 g / mol or less, about 7,500 g / mol or less, about 7,000 g / mol or less, about 6,500 g / mol or less, about 6,000 g / mol or less, about 5,500 g / mol or less, about 5,000 g / mol or less, about 4,500 g / mol or less, about 4,000 g / mol or less, about 3,500 g / mol or less, about 3,000 g / mol or less, about 2,500 g / mol or less, or about 2,000 g / mol or less. Therefore, nonionic polymers may have a weight average molecular weight defined by any two of the endpoints mentioned above. For example, the nonionic polymer may have a weight average molecular weight of about 400 g / mol to about 10,000 g / mol, such as about 400 g / mol to about 9,000 g / mol, about 400 g / mol to about 8,000 g / mol, about 400 g / mol to about 7,000 g / mol, about 400 g / mol to about 6,000 g / mol, about 400 g / mol to about 5,000 g / mol, about 1,000 g / mol to about 10,000 g / mol, about 1,000 g / mol to about 9,000 g / mol, about 1,000 g / mol to about 8,000 g / mol, about 1,000 g / mol to about 7,000 g / mol, about 1,000 g / mol to about 6,000 g / mol, or about 1,000 g / mol to about 5,000 g / mol.

[0043] The polishing composition may include any suitable amount of nonionic polymer (if present). The polishing composition may include about 25 ppm or more of nonionic polymer, such as about 50 ppm or more, about 100 ppm or more, or about 200 ppm or more. Alternatively or additionally, the polishing composition may include about 5000 ppm or less of nonionic polymer, such as about 4000 ppm or less, about 3000 ppm or less, about 2000 ppm or less, or about 1000 ppm or less. Thus, the polishing composition may include an amount of nonionic polymer defined by any two of the endpoints mentioned above. For example, the polishing composition may include a nonionic polymer of about 25 ppm to about 5000 ppm, such as about 25 ppm to about 400 ppm, about 25 ppm to about 3000 ppm, about 25 ppm to about 2000 ppm, about 25 ppm to about 1000 ppm, about 50 ppm to about 5000 ppm, about 50 ppm to about 4000 ppm, about 50 ppm to about 3000 ppm, about 50 ppm to about 2000 ppm, about 50 ppm to about 1000 ppm, about 100 ppm to about 5000 ppm, or about 100 ppm to about 1000 ppm.

[0044] In some embodiments, the chemical-mechanical polishing composition further includes an oxidant. The oxidant may be any suitable oxidant. Without being limited to any particular theory, it is believed that the oxidant can increase the removal rate of the carbon-based thin film when used on a polishing substrate comprising a carbon-based thin film. Non-limiting examples of suitable oxidants include potassium persulfate, cerium ammonium nitrate, peroxides (e.g., hydrogen peroxide), periodates (e.g., sodium periodate or potassium periodate), iodates (e.g., sodium iodate, potassium iodate, or ammonium iodate), persulfates (e.g., sodium persulfate, potassium persulfate, or ammonium persulfate), chlorates (e.g., sodium chlorate or potassium chlorate), chromates (e.g., sodium chromate or potassium chromate), permanganates (e.g., sodium permanganate, potassium permanganate, or ammonium permanganate), bromates (e.g., sodium bromate or potassium bromate), perbromates (e.g., sodium perbromate or potassium perbromate), ferrates (e.g., potassium ferrate), perrhenates (e.g., ammonium perrhenate), perruthenates (e.g., tetrapropylammonium perruthenate), and combinations thereof. In some embodiments, the oxidant is hydrogen peroxide. Polishing compositions may include any suitable amount of oxidant. For example, the polishing composition may include about 0.1 wt.% to about 5 wt.% of an oxidant (e.g., about 0.5 wt.% to about 3 wt.% or about 1 wt.% to about 3 wt.% of an oxidant).

[0045] In some embodiments, the chemical-mechanical polishing composition is free of oxidants. As used herein, the phrase "free of oxidants" means (a) the composition is free of oxidants or (b) the composition contains no more than the amount of trace contaminant material, such amount being insufficient to affect any metal removal rate that the composition can achieve during chemical-mechanical polishing.

[0046] The chemical-mechanical polishing composition includes water. The water may be any suitable water comprising, for example, deionized water or distilled water. In some embodiments, the chemical-mechanical polishing composition may further include one or more organic solvents in combination with water. For example, the polishing composition may further include hydroxyl solvents (e.g., methanol or ethanol), ketone solvents, amide solvents, sulfide solvents, and the like. In some embodiments, the chemical-mechanical polishing composition includes pure water.

[0047] Chemical-mechanical polishing compositions can be produced using any suitable technique, many of which are known to those skilled in the art. Polishing compositions can be prepared in batch or continuous processes. Typically, polishing compositions are prepared by combining the components of a polishing composition in any order. The term "component" as used herein includes individual components (e.g., silicon dioxide abrasive, iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives) and any combination of components (e.g., silicon dioxide abrasive, iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives).

[0048] For example, the polishing composition may be prepared by: (i) providing all or part of the liquid carrier, (ii) dispersing silicon dioxide abrasive, iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives using any suitable method for preparing the dispersion, (iii) adjusting the pH of the dispersion where appropriate, and (iv) adding suitable amounts of any other optional components and / or additives to the mixture as appropriate.

[0049] Alternatively, the polishing composition may be prepared by: (i) providing one or more components (e.g., iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives) in a silicon dioxide abrasive slurry; (ii) providing one or more components (e.g., iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives) in an additive solution; (iii) combining the silicon dioxide abrasive slurry and the additive solution to form a mixture; (iv) adding any other optional additives to the mixture as appropriate; and (v) adjusting the pH of the mixture where appropriate.

[0050] The polishing composition may be supplied in a single-package system containing silicon dioxide abrasive, iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives and water. Alternatively, the polishing composition of the present invention may be supplied in a two-package system containing a silicon dioxide abrasive slurry in a first package and an additive solution in a second package, wherein the silicon dioxide abrasive slurry is substantially composed of or consisting of silicon dioxide abrasive and water, and wherein the additive solution is substantially composed of or consisting of iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives. The characteristics of the polishing composition can be adjusted by changing the blending ratio of the two packages (i.e., the silicon dioxide abrasive slurry and the additive solution).

[0051] Various methods can be used to utilize this dual-pack polishing system. For example, the silica abrasive slurry and additive solution can be delivered to the polishing table via different pipes joined and connected at the outlet of the supply pipe. The silica abrasive slurry and additive solution can be mixed shortly before or just before polishing, or can be supplied to the polishing table simultaneously. Furthermore, when mixing the two packets, deionized water can be added as desired to adjust the polishing composition and obtain substrate polishing characteristics.

[0052] Similarly, three, four or more package systems may be used in conjunction with the present invention, wherein each of the plurality of containers contains different components, one or more optional components and / or one or more of the same components at different concentrations of the chemimechanical polishing composition of the present invention.

[0053] To mix components contained in two or more storage devices to produce a polishing composition at or near the point of use, such storage devices typically provide one or more flow lines from each storage device to the point of use (e.g., a platform, polishing pad, or substrate surface) of the polishing composition. As used herein, the term "point of use" refers to the point where the polishing composition is applied to the substrate surface (e.g., the polishing pad or the substrate surface itself). The term "flow line" means the path from an individual storage container to the point of use of the component stored therein. Flow lines may each lead directly to the point of use, or two or more flow lines may be combined at any point into a single flow line leading to the point of use. Furthermore, any of the flow lines (e.g., individual flow lines or combined flow lines) may first lead to one or more other devices (e.g., pumping devices, measuring devices, mixing devices, etc.) before reaching the point of use of the component.

[0054] The components of the polishing composition may be delivered independently to the point of use (e.g., delivered to the substrate surface and then mixed during the polishing process), or one or more of the components may be combined before delivery to the point of use (e.g., shortly before or just before delivery to the point of use). If the components are combined 5 minutes or less before being added to the platform in mixed form, such as about 4 minutes or less, about 3 minutes or less, about 2 minutes or less, about 1 minute or less, about 45 seconds or less, about 30 seconds or less, about 10 seconds or less, or even simultaneously with the delivery of the components to the point of use (e.g., at the dispenser), then the components are combined "just before delivery to the point of use". If the components are combined within 5 m of the point of use, such as within 1 m of the point of use, or even within 10 cm of the point of use (e.g., within 1 cm of the point of use), then the components may also be combined "immediately before delivery to the point of use".

[0055] When two or more components of a polishing composition are combined before reaching the point of use, the components can be combined in a flow line and delivered to the point of use without using a mixing device. Alternatively, one or more flow lines may lead to a mixing device to facilitate the combination of two or more components. Any suitable mixing device may be used. For example, the mixing device may be a nozzle or injector (e.g., a high-pressure nozzle or injector) through which two or more components flow. Alternatively, the mixing device may be a container-type mixing device comprising: one or more inlets through which two or more components of the polishing slurry are introduced into the mixer; and at least one outlet through which the mixed components exit the mixer to be delivered directly or via other elements of the device (e.g., via one or more flow lines) to the point of use. In addition, the mixing device may include more than one chamber, each chamber having at least one inlet and at least one outlet, wherein two or more components are combined in each chamber. If a container-type mixing device is used, the mixing device preferably includes a mixing mechanism to further facilitate the combination of components. Mixing mechanisms are generally known in the industry and include agitators, mixers, stirrers, stirring baffles, gas jet systems, vibrators, etc.

[0056] The polishing composition may also be provided in the form of a concentrate intended to be diluted with an appropriate amount of water prior to use. In this embodiment, the polishing composition concentrate comprises the components of the polishing composition in amounts such that, when the concentrate is diluted 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 listed above for each component. For example, iron cations, ligands, cationic polymers, optional nonionic polymers, and / or any other optional additives may each be present in the concentrate in an amount approximately twice (e.g., approximately three times, approximately four times, or approximately five times) the concentration listed above for each component, so that when the concentrate is diluted with equal volumes of water (e.g., two equal volumes of water, three equal volumes of water, or four equal volumes of water, respectively), each component will be present in the polishing composition in an amount within the range stated above for each component. In addition, those skilled in this art will understand that the concentrate may contain an appropriate fraction of water present in the final polishing composition to ensure that the iron cations, ligands, cationic polymers, optional nonionic polymers and / or any other optional additives are at least partially or completely dissolved in the concentrate.

[0057] The present invention further provides a method for chemically-mechanically polishing a substrate, comprising: (i) providing a substrate, (ii) providing a polishing pad, (iii) providing a chemically-mechanically polishing composition comprising: (a) a silicon dioxide abrasive, (b) iron cations, (c) ligands, (d) a cationic polymer and (e) water, (iv) contacting the substrate with the polishing pad and the chemically-mechanically polishing composition, and (v) moving the polishing pad and the chemically-mechanically polishing composition relative to the substrate to abrade at least a portion of the substrate to polish the substrate.

[0058] In some embodiments, the present invention provides a method for chemically-mechanically polishing a substrate, comprising: (i) providing a substrate, (ii) providing a polishing pad, (iii) providing a chemically-mechanically polishing composition comprising: (a) a silicon dioxide abrasive, (b) an iron cation, (c) a ligand, (d) a cationic polymer, (e) a nonionic polymer and (f) water, (iv) contacting the substrate with the polishing pad and the chemically-mechanically polishing composition, and (v) moving the polishing pad and the chemically-mechanically polishing composition relative to the substrate to abrade at least a portion of the substrate to polish the substrate.

[0059] The chemical-mechanical polishing composition can be used to polish any suitable substrate, and is particularly suitable for polishing substrates comprising at least one layer (typically a surface layer) of a low-dielectric material. Suitable substrates comprise wafers used in the semiconductor industry. Wafers typically comprise, for example, metals, metal oxides, metal nitrides, metal composites, metal alloys, low-dielectric materials, or combinations thereof, or are composed of the like. The method of the present invention is particularly suitable for polishing substrates comprising carbon-based thin films (e.g., carbon hard masking materials). In some embodiments, the substrate comprises a carbon-based thin film, wherein at least a portion of the carbon-based thin film is abraded at a certain removal rate (Å / min) to polish the substrate.

[0060] In some embodiments, the substrate comprises a carbon-based thin film. The carbon-based thin film can be any suitable material containing carbon (e.g., a low-dielectric material), many of which are known in the art. In some embodiments, the carbon-based thin film comprises more than about 50 wt.% carbon, such as more than about 60 wt.% carbon, more than about 70 wt.% carbon, more than about 80 wt.% carbon, more than about 90 wt.% carbon, or more than about 95 wt.% carbon. The carbon-based thin film can have any suitable phase. For example, the carbon-based thin film can be amorphous, crystalline, or a combination thereof. In some embodiments, the carbon-based thin film is amorphous. Examples of carbon-based thin films are described in the following literature: Weigand et al. ("Evaluating spin-on carbon materials at low temperatures for high wiggling resistance", Advanced Etch Technology for Nanopatterning II, Vol. 8685, International Society for Optics and Photonics, 2013) and Kim et al. ("Study on the etching characteristics of amorphous carbon layer in oxygen plasma with carbonyl sulfide", J. Vac. Sci. Technol. A, 31, 021301, pp. 1-7, (2013)).

[0061] In some embodiments, the substrate comprises a carbon-based thin film, and at least a portion of the carbon-based thin film is ground at a certain removal rate (Å / min) to polish the substrate. When a substrate comprising a carbon-based thin film is polished according to the method of the present invention, the chemical-mechanical polishing composition of the present invention is expected to exhibit a high removal rate. For example, when the polishing substrate according to embodiments of the present invention comprises a carbon-based thin film, the polishing composition is expected to exhibit a carbon-based thin film removal rate of about 200 Å / min or higher, such as about 300 Å / min or higher, about 400 Å / min or higher, about 500 Å / min or higher, about 600 Å / min or higher, about 700 Å / min or higher, about 800 Å / min or higher, about 900 Å / min or higher, about 1,000 Å / min or higher, about 1,100 Å / min or higher, about 1,200 Å / min or higher, about 1,500 Å / min or higher, about 2,000 Å / min or higher, about 3,000 Å / min or higher, or about 4,000 Å / min or higher.

[0062] In some embodiments, the substrate further comprises silicon oxide, silicon nitride, polycrystalline silicon, titanium nitride, or combinations thereof, and at least a portion of the silicon oxide, silicon nitride, polycrystalline silicon, or titanium nitride is polished at a certain removal rate (Å / min). In embodiments where the substrate further comprises silicon oxide, silicon nitride, polycrystalline silicon, titanium nitride, or combinations thereof, the removal rate (Å / min) of the carbon-based film is greater than the removal rate (Å / min) of the silicon oxide, silicon nitride, polycrystalline silicon, or titanium nitride. In other words, in some embodiments, the polishing composition and method exhibit selective removal of the carbon-based film, with almost no removal of silicon oxide, silicon nitride, polycrystalline silicon, titanium nitride, or combinations thereof. For example, the removal rate (Å / min) of the carbon-based thin film may be at least 10 times that of silicon oxide, silicon nitride, polycrystalline silicon, or titanium nitride; at least 20 times that of silicon oxide, silicon nitride, polycrystalline silicon, or titanium nitride; or at least 40 times that of silicon oxide, silicon nitride, polycrystalline silicon, or titanium nitride.

[0063] In embodiments where the substrate further comprises silicon oxide, the silicon oxide may be any suitable silicon oxide, many of which are known in the art. Suitable types of silicon oxide include (but are not limited to) silicon oxide films derived from tetraethyl orthosilicate (TEOS), borosilicate glass (BPSG), plasma-reinforced tetraethyl orthosilicate (PETEOS), thermal oxides, undoped silicate glass, and high-density plasma (HDP) oxides. When polishing a substrate comprising silicon oxide according to the method of the present invention, the chemical-mechanical polishing composition of the present invention desiccates to exhibit a lower removal rate. For example, when the substrate being polished according to embodiments of the present invention comprises silicon oxide, the polishing composition is expected to exhibit a silicon oxide removal rate of about 500 Å / min or lower, such as about 250 Å / min or lower, about 200 Å / min or lower, about 150 Å / min or lower, about 100 Å / min or lower, about 50 Å / min or lower, about 25 Å / min or lower, about 10 Å / min or lower, or about 5 Å / min or lower. In some embodiments, the polishing composition exhibits a silicon oxide removal rate that is too low to be detectable. In some embodiments, the removal rate (Å / min) of the carbon-based film is at least 50 times (e.g., 50-1000, 50-500, 50-400, 50-300, or 50-200 times) the removal rate (Å / min) of the silicon oxide. In some embodiments, the removal rate (Å / min) of the carbon-based thin film is at least 100 times (e.g., 100-1000, 100-500, 100-400, 100-300, or 100-200) times that of silicon oxide. In some embodiments, the removal rate (Å / min) of the carbon-based thin film is at least 200 times (e.g., 200-1000, 200-500, 200-400, or 200-300) times that of silicon oxide.

[0064] In embodiments where the substrate further comprises polycrystalline silicon, the polycrystalline silicon can be any suitable polycrystalline silicon, many of which are known in the art. The polycrystalline silicon can have any suitable phase and can be amorphous, crystalline, or a combination thereof. When polishing a substrate comprising polycrystalline silicon according to the method of the present invention, the chemical-mechanical polishing composition of the present invention is expected to exhibit a low removal rate. For example, when polishing a substrate comprising polycrystalline silicon according to embodiments of the present invention, the polishing composition is expected to exhibit a polycrystalline silicon removal rate of about 500 Å / min or lower, such as about 250 Å / min or lower, about 200 Å / min or lower, about 150 Å / min or lower, about 100 Å / min or lower, about 50 Å / min or lower, about 25 Å / min or lower, about 10 Å / min or lower, or about 5 Å / min or lower. In some embodiments, the polishing composition exhibits a polycrystalline silicon removal rate that is too low to be detectable.

[0065] In embodiments where the substrate further comprises silicon nitride, the silicon nitride may be any suitable silicon nitride, many of which are known in the art. When polishing a substrate comprising silicon nitride according to the method of the present invention, the chemical-mechanical polishing composition of the present invention is expected to exhibit a low removal rate. For example, when polishing a substrate comprising silicon nitride according to embodiments of the present invention, the polishing composition is expected to exhibit a silicon nitride removal rate of about 500 Å / min or lower, such as about 250 Å / min or lower, about 200 Å / min or lower, about 150 Å / min or lower, about 100 Å / min or lower, about 50 Å / min or lower, about 25 Å / min or lower, about 10 Å / min or lower, or about 5 Å / min or lower. In some embodiments, the polishing composition exhibits a silicon nitride removal rate that is too low to be detectable.

[0066] In embodiments where the substrate further comprises titanium nitride, the titanium nitride can be any suitable titanium nitride, many of which are known in the art. When polishing a substrate comprising titanium nitride according to the method of the present invention, the chemical-mechanical polishing composition of the present invention desirably exhibits a low removal rate. For example, when polishing a substrate comprising titanium nitride according to embodiments of the present invention, the polishing composition desirably exhibits a titanium nitride removal rate of about 500 Å / min or lower, such as about 250 Å / min or lower, about 200 Å / min or lower, about 150 Å / min or lower, about 100 Å / min or lower, about 50 Å / min or lower, about 25 Å / min or lower, about 10 Å / min or lower, or about 5 Å / min or lower. In some embodiments, the polishing composition exhibits a titanium nitride removal rate that is too low to be detectable.

[0067] When polishing a substrate, the polishing composition of the present invention is expected to exhibit fewer particle defects, as measured by suitable techniques. Particle defects on a substrate polished using the polishing composition of the present invention can be measured by any suitable technique. For example, laser light scattering techniques (e.g., dark field normal beam composite (DCN) and dark field oblique beam composite (DCO)) can be used to measure particle defects on the polished substrate. Suitable instruments for assessing the particle defect rate can be purchased, for example, from KLA-Tencor (e.g., a SURFSCAN™ SPI instrument operating at a 120 nm or 160 nm threshold).

[0068] The chemical-mechanical polishing composition and method of the present invention are particularly suitable for use in conjunction with chemical-mechanical polishing equipment. Typically, such equipment includes a platform that moves during use and has a speed generated by orbital, linear, or circular motion; a polishing pad that contacts the platform and moves with the platform; and a carrier that holds the substrate by bringing it into contact with the surface of the polishing pad and moving it relative to the surface of the polishing pad. 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 polish at least a portion of the substrate.

[0069] A chemical-mechanical polishing composition can be used to polish a substrate using any suitable polishing pad (e.g., a polishing surface). Suitable polishing pads include, for example, woven and non-woven polishing pads. Furthermore, suitable polishing pads may comprise any suitable polymer having 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, products thereof, and mixtures thereof. Soft polyurethane polishing pads are particularly useful in conjunction with the polishing method of the present invention. Typical pads include (but are not limited to) SURFIN™ 000, SURFIN™ SSW1, SPM3100 (Eminess Technologies); POLITEX™ from Dow Chemical Company (Newark, DE); POLYPAS™ 27 from Fujibo (Osaka, JP); and EPIC™ D100 or EXPLANAR™ E6088 from Entegris Corporation (Billerica, MA).

[0070] Desiredly, the chemical-mechanical polishing equipment further includes an in-situ polishing endpoint detection system, many of which are known in the industry. Techniques for inspecting and monitoring the polishing process by analyzing light or other radiation reflected from the surface of the substrate being polished are known in the industry. Such methods are described, for example, in U.S. Patent Nos. 5,196,353, 5,433,651, 5,609,511, 5,643,046, 5,658,183, 5,730,642, 5,838,447, 5,872,633, 5,893,796, 5,949,927, and 5,964,643. Ideally, inspecting or monitoring the progress of the polishing process on the substrate being polished would enable the determination of the polishing endpoint, i.e., when to terminate the polishing process on a particular substrate.

[0071] The present invention described herein (including embodiments) can be used alone or in combination with one or more other embodiments or embodiments. Without limiting the foregoing description, certain non-limiting embodiments of the invention numbered 1-47 are provided below. As will be apparent to those skilled in the art upon reading this disclosure, each individually numbered embodiment can be used or combined with any of the previously or subsequently individually numbered embodiments. This is intended to support all such combinations of embodiments, and is not limited to the combinations of embodiments explicitly provided below:

[0072] Example (1) In Example (1), a chemical-mechanical polishing composition is presented, comprising: (a) a silicon dioxide abrasive, (b) iron cations, (c) ligands, (d) a cationic polymer, (e) a nonionic polymer, if applicable, and (f) water.

[0073] (2) In Example (2), a polishing composition as in Example (1) is presented, wherein the polishing composition comprises about 0.001 wt.% to about 10 wt.% of the silicon dioxide abrasive.

[0074] (3) In Example (3), a polishing composition as in Example (1) or (2) is presented, wherein the polishing composition comprises about 0.05 wt.% to about 5 wt.% of the silicon dioxide abrasive.

[0075] (4) In Example (4), a polishing composition as in any one of Examples (1) to (3) is presented, wherein the silica abrasive is colloidal silica.

[0076] (5) The polishing composition presented in Example (5) is any one of Examples (1) to (4), wherein the polishing compound has a pH of about 1 to about 7.

[0077] (6) The polishing composition presented in Example (6) is any one of Examples (1) to (5), wherein the polishing compound has a pH of about 1 to about 4.

[0078] (7) In Example (7), a polishing composition as in any one of Examples (1) to (6) is presented, wherein the silicon dioxide abrasive has a positive ζ potential.

[0079] (8) In Example (8), a polishing composition as in any one of Examples (1) to (7) is presented, wherein the silicon dioxide abrasive has a ζ potential of 10 mV or higher.

[0080] (9) In Example (9), a polishing composition as in any one of Examples (1) to (8) is presented, wherein the silicon dioxide abrasive has a ζ potential of 20 mV or higher.

[0081] (10) In Example (10), a polishing composition as in any one of Examples (1) to (9) is presented, wherein the iron cation is present in the polishing composition in an amount of about 1 ppm to about 1000 ppm based on the total weight of the polishing composition.

[0082] (11) In Example (11), a polishing composition as in any one of Examples (1) to (10) is presented, wherein the iron cation is present in the polishing composition in an amount of about 10 ppm to about 500 ppm based on the total weight of the polishing composition.

[0083] (12) In Example (12), a polishing composition as in any one of Examples (1) to (11) is presented, wherein the formulation is phosphoric acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, fumaric acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, maleic acid, penteneic acid, mucoconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, tartaric acid, their salts or combinations thereof.

[0084] (13) In Example (13), a polishing composition as in any one of Examples (1) to (12) is presented, wherein the formulation is malonic acid or a salt thereof.

[0085] (14) In Example (14), a polishing composition as in any one of Examples (1) to (13) is presented, wherein the iron cation and the formulation are present in the composition in a molar ratio of 1:1 to 1:5.

[0086] (15) In Example (15), a polishing composition as in any one of Examples (1) to (14) is presented, wherein the iron cation and the formulation are present in the composition in a molar ratio of 1:1 to 1:3.

[0087] (16) In Example (16) a polishing composition as in any one of Examples (1) to (15) is presented, wherein the cationic polymer includes poly(vinylimidazolium), polylysine, poly(methacryloxyethyltrimethylammonium chloride) (polyMADQUAT), and poly(diallyldimethylammonium chloride). (polyDADMAC), poly(dimethylamine-co-epiochlorohydrin), poly[bis(2-chloroethyl) ether-alternating-1,3-bis[3-(dimethylamino)propyl]urea], copolymers of hydroxyethyl cellulose and diallyl dimethylammonium, copolymers of acrylamide and diallyl dimethylammonium, terpolymers of quaternary ammonium hydroxyethyl cellulose ethoxylate, copolymers of vinylpyrrolidone and quaternary ammonium dimethylaminoethyl methacrylate, copolymers of vinylpyrrolidone and quaternary ammonium vinylimidazolium, terpolymers of vinylcaprolactam, vinylpyrrolidone and quaternary ammonium vinylimidazolium, methylsulfate 3-methyl-1-vinylimidazolium salt-N-vinylpyrrolidone copolymer, copolymers of vinylpyrrolidone and diallyl dimethylammonium, their salts or combinations thereof.

[0088] (17) In Example (17), a polishing composition as in any one of Examples (1) to (16) is presented, wherein the cationic polymer is poly(diallyldimethylammonium chloride) (polyDADMAC) or a salt thereof.

[0089] (18) In Example (18), a polishing composition as in any one of Examples (1) to (17) is presented, wherein the polishing composition comprises a nonionic polymer and the nonionic polymer is polyvinylpyrrolidone.

[0090] (19) In Example (19), a polishing composition as in any one of Examples (1) to (18) is presented, wherein the polishing composition further comprises a biocide.

[0091] (20) In Example (20), a polishing composition as in any one of Examples (1) to (19) is presented, wherein the polishing composition further comprises an oxidant.

[0092] (21) A method of chemically-mechanically polishing a substrate is presented in Example (21), comprising: providing a substrate, providing a polishing pad, providing a chemically-mechanically polishing composition comprising: (a) a silicon dioxide abrasive, (b) an iron cation, (c) a ligand, (d) a cationic polymer, and (e) water, contacting the substrate with the polishing pad and the chemically-mechanically polishing composition, and moving the polishing pad and the chemically-mechanically polishing composition relative to the substrate to abrade at least a portion of the substrate to polish the substrate.

[0093] (22) In Example (22), the method as in Example (21) is presented, wherein the polishing composition comprises about 0.001 wt.% to about 10 wt.% of the silicon dioxide abrasive.

[0094] (23) The method of Example (21) or (22) is presented in Example (23), wherein the polishing composition comprises about 0.05 wt.% to about 5 wt.% of the silicon dioxide abrasive.

[0095] (24) In Example (24), the method of any one of Examples (21) to (23) is presented, wherein the silica abrasive is colloidal silica.

[0096] (25) The method of any one of Examples (21) to (24) is presented in Example (25), wherein the polishing compound has a pH of about 1 to about 7.

[0097] (26) The method of any one of Examples (21) to (25) is presented in Example (26), wherein the polishing compound has a pH of about 1 to about 4.

[0098] (27) In Example (27), the method of any one of Examples (21) to (26) is presented, wherein the silicon dioxide abrasive has a positive ζ potential.

[0099] (28) In Example (28), the method of any one of Examples (21) to (27) is presented, wherein the silicon dioxide abrasive has a ζ potential of 10 mV or higher.

[0100] (29) In Example (29), the method of any one of Examples (21) to (28) is presented, wherein the silicon dioxide abrasive has a ζ potential of 20 mV or higher.

[0101] (30) In Example (30), the method of any one of Examples (21) to (29) is presented, wherein the iron cation is present in the polishing composition in an amount of about 1 ppm to about 1000 ppm based on the total weight of the polishing composition.

[0102] (31) In Example (31), the method of any one of Examples (21) to (30) is presented, wherein the iron cation is present in the polishing composition in an amount of about 10 ppm to about 500 ppm based on the total weight of the polishing composition.

[0103] (32) In Example (32), the method of any one of Examples (21) to (31) is presented, wherein the formulation is phosphoric acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, fumaric acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, maleic acid, penteneic acid, mucoconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, tartaric acid, their salts or combinations thereof.

[0104] (33) The method of any one of Examples (21) to (32) is presented in Example (33), wherein the ligand is malonic acid or a salt thereof.

[0105] (34) The method of any one of Examples (21) to (33) is presented in Example (34), wherein the iron cation and the ligand are present in the composition in a molar ratio of 1:1 to 1:5.

[0106] (35) The method of any one of Examples (21) to (34) is presented in Example (35), wherein the iron cation and the ligand are present in the composition in a molar ratio of 1:1 to 1:3.

[0107] (36) In Example (36), the method of any one of Examples (21) to (35) is presented, wherein the cationic polymer includes poly(vinylimidazolium), polylysine, poly(methacryloxyethyltrimethylammonium chloride) (polyMADQUAT), and poly(diallyldimethylammonium chloride). (polyDADMAC), poly(dimethylamine-co-epiochlorohydrin), poly[bis(2-chloroethyl) ether-alternating-1,3-bis[3-(dimethylamino)propyl]urea], copolymers of hydroxyethyl cellulose and diallyl dimethylammonium, copolymers of acrylamide and diallyl dimethylammonium, terpolymers of quaternary ammonium hydroxyethyl cellulose ethoxylate, copolymers of vinylpyrrolidone and quaternary ammonium dimethylaminoethyl methacrylate, copolymers of vinylpyrrolidone and quaternary ammonium vinylimidazolium, terpolymers of vinylcaprolactam, vinylpyrrolidone and quaternary ammonium vinylimidazolium, methylsulfate 3-methyl-1-vinylimidazolium salt-N-vinylpyrrolidone copolymer, copolymers of vinylpyrrolidone and diallyl dimethylammonium, their salts or combinations thereof.

[0108] (37) In Example (37), the method of any one of Examples (21) to (36) is presented, wherein the cationic polymer comprises poly(diallyldimethylammonium chloride) (polyDADMAC) or a salt thereof.

[0109] (38) The method of any one of Examples (21) to (37) is presented in Example (38), wherein the polishing composition further comprises a nonionic polymer.

[0110] (39) The method of Example (38) is presented in Example (39), wherein the nonionic polymer comprises polyvinylpyrrolidone.

[0111] (40) The method of any one of Examples (21) to (39) is presented in Example (40), wherein the polishing composition further comprises a biocide.

[0112] (41) In Example (41), the method of any one of Examples (21) to (40) is presented, wherein the polishing composition further comprises an oxidant.

[0113] (42) In Example (42), the method of any one of Examples (21) to (41) is presented, wherein the substrate comprises a carbon-based thin film, and wherein at least a portion of the carbon-based thin film is polished at a certain removal rate (Å / min) to polish the substrate.

[0114] (43) In Example (43), the method of Example (42) is presented, wherein the substrate further comprises silicon oxide, silicon nitride, polycrystalline silicon, titanium nitride or a combination thereof, and wherein at least a portion of the silicon oxide, silicon nitride, polycrystalline silicon or titanium nitride is polished at a certain removal rate (Å / min) to polish the substrate.

[0115] (44) In Example (44), the method as in Example (43) is presented, wherein the removal rate (Å / min) of the carbon-based film is greater than the removal rate (Å / min) of the silicon oxide, silicon nitride, polycrystalline silicon or titanium nitride.

[0116] (45) In Example (45), the method of Example (44) is presented, wherein the substrate further comprises silicon oxide, wherein at least a portion of the silicon oxide is polished at a certain removal rate (Å / min) to polish the substrate, and wherein the removal rate (Å / min) of the carbon-based film is at least 50 times that of the removal rate (Å / min) of the silicon oxide.

[0117] (46) In Example (46), the method as in Example (45) is presented, wherein the removal rate (Å / min) of the carbon-based film is at least 100 times that of the removal rate (Å / min) of the silicon oxide.

[0118] (47) In Example (47), the method as in Example (46) is presented, wherein the removal rate (Å / min) of the carbon-based film is at least 200 times that of the removal rate (Å / min) of the silicon oxide.

[0119] Examples The following examples further illustrate the invention, but should not be construed as limiting the scope of the invention in any way.

[0120] The following abbreviations are used throughout the examples: removal rate (RR); spin-coated carbon (SOC); tetraethyl orthosilicate (TEOS); and silicon nitride (SiN).

[0121] In the following examples, SOC, TEOS, or SiN were coated onto silicon, and the resulting patterned substrates were polished using a Logitech 2 benchtop polisher at a pressure of 1 PSI (6.85 kPa) or 3 PSI (20.55 kPa) using a NEXPLANAR™ E6088 purchased from Entegris Corporation (Billerica, MA). This pressure was adjusted using a product commercially identified as A82 (3M, St. Paul, MN). The Logitech polishing parameters were as follows: head speed = 93 rpm, stage speed = 87 rpm, total flow rate = 50 mL / min. The removal rate was calculated by measuring the film thickness using spectral elliptic polarization and subtracting the final thickness from the initial thickness.

[0122] Example 1 This example provides particle size distribution analysis of the silica particles A, silica particles B and a 1:1 mixture of silica particles A and B (particles A / B) of the present invention used in Examples 2-4.

[0123] The particle size distribution of silicon dioxide particles A, silicon dioxide particles B, and a 1:1 mixture of silicon dioxide particles A and B (particles A / B) was analyzed using scanning transmission electron microscopy. The particle size distribution and cumulative particle size distribution are shown in Figure 1 and Figure 2, respectively.

[0124] As is clear from the results presented in Figures 1 and 2, silicon dioxide particles A have an average particle size greater than 110 nm, silicon dioxide particles B have an average particle size less than 100 nm, and a 1:1 mixture of silicon dioxide particles A and B (particles A / B) has an average particle size of approximately 90-110 nm. Example 2

[0125] This example demonstrates the preparation of a polishing composition according to the present invention comprising silicon dioxide abrasive, iron cations, ligands, and a cationic polymer. Polishing compositions 1A-1I are used below to demonstrate the beneficial polishing properties provided by the polishing compositions prepared according to the present invention.

[0126] For each of the compositions used in this example, silicon dioxide particles A having a positive natural zeta potential and particle size distribution as analyzed in Example 1 were combined with iron cations, ligands, and a cationic polymer. The cationic polymer (i.e., polydiallyldimethylammonium chloride (“polyDADMAC”), the iron cation (i.e., the iron compound described herein), and the ligand (i.e., malonic acid) in a molar ratio of 2:1 to the iron cation were added to each polishing composition in the amounts specified in Table 1, and the pH of each polishing composition was adjusted to 2.5. Polishing compositions 1A-1I have the obtained average particle size and silicon dioxide particle zeta potential as specified in Table 1. Table 1: Polishing Compositions 1A-1I polishing Composition Silicon dioxide abrasive (wt.%) [Fe] (wt.%) cationic polymers (wt.%) granularity (nm) ζ potential (mV) polishing Composition 1A 1.5 0.02 0.0066 122 45 polishing Composition 1B 1 0.01 0.013 124 49 polishing Composition 1C 1.8 0.01 0.0033 121 47 polishing Composition 1D 1.8 0.04 0.0033 127 42 polishing Composition 1E 1 0.04 0.0033 127 45 polishing Composition 1F 1.8 0.01 0.013 126 46 polishing Composition 1G 1 0.04 0.013 132 43 polishing Composition 1H 1.8 0.04 0.013 134 43 polishing Composition 1I 1 0.01 0.0033 127 48

[0127] Patterned substrates, including SOC, TEOS, or SiN, were polished using polishing composition 1A-1I as defined in Table 1 under the same conditions (i.e., pressure of 3 PSI (20.55 kPa), head speed of 93 rpm, stage speed of 87 rpm, and total flow rate of 50 mL / min). In this specific example, the SOC patterned substrate was used as a substitute to measure the carbon removal rate of commercially available carbon thin film materials. After polishing, the RR of SOC, TEOS, and SiN was measured, and the results are presented in Table 2 and plotted in Figure 3. Table 2: Polishing Removal Rate of Polishing Composition 1A-1I polishing Composition SOC (Å / min) TEOS (Å / min) SiN (Å / min) polishing Composition 1A (This invention) 748 25 13 polishing Composition 1B (This invention) 207 11 4 polishing Composition 1C (This invention) 271 26 12 polishing Composition 1D (This invention) 947 32 15 polishing Composition 1E (This invention) 1267 27 16 polishing Composition 1F (This invention) 384 26 11 polishing Composition 1G (This invention) 3499 12 13 polishing Composition 1H (This invention) 4563 twenty two 16 polishing Composition 1I (This invention) 325 12 7

[0128] As can be seen from the results presented in Table 2 and Figure 3, polishing compositions 1A, 1D, 1E, 1G and 1H exhibit a SOC removal selectivity greater than 20:1 relative to TEOS removal, and polishing compositions 1A-1I exhibit a SOC removal selectivity greater than 20:1 relative to SiN removal in all cases.

[0129] Furthermore, Table 2 shows that polishing compositions 1G and 1H, which contain the most silicon dioxide abrasive, iron cations, ligands, and cationic polymers in polishing compositions 1A-1I, provide the highest SOC removal rates. As this data clarifies, increasing the cationic polymer concentration and / or increasing the iron cation concentration increases the carbon removal rate. These results are unexpected and contrary to the expectation that cationic polymers would act as morphology control agents that inhibit polishing and reduce the carbon removal rate. Example 3

[0130] This example demonstrates the effect of particle size distribution on the polishing performance provided by the polishing composition prepared according to the present invention.

[0131] For each of the compositions used in this example, silicon dioxide particles A and B, having a positive natural zeta potential and particle size distribution as analyzed in Example 1, were combined with iron cations (200 ppm), ligands (400 ppm), and cationic polymers (133 ppm) in the amounts (ratios) specified in Table 3. The cationic polymers (i.e., polydiallyldimethylammonium chloride (“polyDADMAC”), iron cations (i.e., the iron compounds described herein), and ligands (i.e., malonic acid) in a molar ratio of 2:1 to the iron cations were added to the polishing compositions, and the pH of each polishing composition was adjusted to 2.15.

[0132] Patterned substrates, including SOC or TEOS, were polished using polishing compositions 2A-2E as defined in Table 3 under the same conditions (i.e., pressure of 1 PSI (6.85 kPa), head speed of 93 rpm, stage speed of 87 rpm, and total flow rate of 50 mL / min). In this specific example, the SOC patterned substrate was used as a substitute to measure the carbon removal rate of commercially available carbon thin film materials. After polishing, the RR of SOC and TEOS was measured, and the results are presented in Table 3. Table 3: Removal rate of polishing compositions 2A-2E as a function of particle size distribution polishing Composition Silicon dioxide particles A (wt.%) Silica particles B (wt.%) SOC (Å / min) TEOS (Å / min) polishing Composition 2A 1.8 0 517 29 polishing Composition 2B 0 1.8 254 36 polishing Composition 2C 0.45 1.35 328 39 polishing Composition 2D 0.9 0.9 622 25 polishing Composition 2E 1.35 0.45 514 32

[0133] As the results presented in Table 3 are clear, the polishing composition 2D having a 1:1 mixture of silica particles A and B provides the highest SOC removal rate and the greatest SOC removal selectivity relative to TEOS removal. Example 4

[0134] This example demonstrates the effect of nonionic polymers on the polishing performance provided by the polishing composition prepared according to the present invention.

[0135] For each of the compositions used in this example, silicon dioxide particles A having a positive natural zeta potential and particle size distribution as analyzed in Example 1 are combined with iron cations (200 ppm), ligands (400 ppm), and cationic polymers (133 ppm). Polishing composition 3B is the same as polishing composition 3A, except that polishing composition 3B further contains a nonionic polymer (100 ppm). The cationic polymer (i.e., polydiallyldimethylammonium chloride ("polyDADMAC")), iron cations (i.e., iron compounds as described herein), ligands (i.e., malonic acid) in a molar ratio of 2:1 to the iron cations, and, where appropriate, a nonionic polymer (i.e., polyvinylpyrrolidone) are added to the polishing composition, and the pH of each polishing composition is adjusted to 2.15.

[0136] Patterned substrates, including SOC or TEOS, were polished using polishing compositions 3A and 3B as defined in Table 4 under the same conditions (i.e., pressure of 1 PSI (6.85 kPa), head speed of 93 rpm, stage speed of 87 rpm, and total flow rate of 50 mL / min). In this specific example, the SOC patterned substrate was used as a substitute to measure the carbon removal rate of commercially available carbon film materials. After polishing, the RR of SOC and TEOS was measured, and the results are presented in Table 4. Table 4: Removal rates of polishing compositions 3A and 3B varying with nonionic polymers. polishing Composition nonionic polymers (ppm) SOC (Å / min) TEOS (Å / min) polishing Composition 3A 0 517 29 polishing Composition 3B 100 1161 0

[0137] As is clear from the results presented in Table 4, polishing compositions 3A and 3B each provide high SOC removal rates and good SOC removal selectivity relative to TEOS removal. Furthermore, Table 4 shows that, compared to polishing composition 3A which does not contain a nonionic polymer, polishing composition 3B, which further contains a nonionic polymer (i.e., polyvinylpyrrolidone), provides a higher SOC removal rate and greater SOC removal selectivity relative to TEOS removal.

[0138] All references cited herein (including publications, patent applications and patents) are incorporated herein by reference as if each reference were individually and specifically indicated to be incorporated herein by reference and its full text were listed herein.

[0139] Unless otherwise specified herein or in obvious contradiction in the context, the terms “a (a and an),” “the,” and “at least one,” and similar designations used in the context of setting forth the invention (particularly in the context of the claims below) shall be construed as encompassing both the singular and the plural. Unless otherwise specified herein or in obvious contradiction in the context, the term “at least one” (e.g., “at least one of A and B”) used immediately following a list of one or more items shall be construed as meaning selected from one item (A or B) or any combination of two or more of the listed items (A and B). Unless otherwise stated, the terms “comprising,” “having,” “including,” and “containing” shall be understood as open-ended terms (i.e., meaning “including but not limited to”). Unless otherwise specified herein, the numerical ranges listed herein are intended only as shorthand for individually referring to each individual value falling within these ranges, and each individual value is incorporated into the specification as if individually listed herein. Unless otherwise stated herein or otherwise obviously contradicted by the context, all methods described herein may be practiced in any suitable order. Unless otherwise claimed, any and all examples or exemplary language (e.g., "such as") used herein are intended only to better illustrate the invention and do not limit its scope. No language in this specification should be construed as indicating that any unclaimed element is essential for the practice of this invention.

[0140] Preferred embodiments of the invention are described herein, including the best modes known to the inventors for carrying out the invention. Variations of these preferred embodiments will be apparent to those skilled in the art upon reading the foregoing description. The inventors expect those skilled in the art to appropriately employ these variations, and the inventors expect the invention to be practiced in ways other than those specifically described herein. Therefore, the invention includes all modifications and equivalents of the subject matter cited in the appended claims as permitted by applicable law. Furthermore, unless otherwise specified herein or otherwise obviously contradicted by the context, any combination of the foregoing elements in all possible variations is covered by this invention. [Simplified Explanation of the Diagram]

[0010] Figure 1 is a graph showing the particle size distribution of silicon dioxide particles A, silicon dioxide particles B, and a 1:1 mixture of silicon dioxide particles A and B (particles A / B), as illustrated in Example 1.

[0011] Figure 2 is a graph showing the cumulative particle size distribution of silicon dioxide particles A, silicon dioxide particles B, and a 1:1 mixture of silicon dioxide particles A and B (particles A / B), as illustrated in Example 1.

[0012] Figure 3 is a graph showing the carbon removal rate (Å / min) of polishing composition 1A-1I, as illustrated in Example 2.

Claims

1. A chemical-mechanical polishing composition comprising: (a) about 0.001 wt.% to about 10 wt.% of a silicon dioxide abrasive having a positive zeta potential, (b) an iron cation, wherein the iron cation is present in the polishing composition in an amount of about 1 ppm to about 1000 ppm based on the total weight of the polishing composition, (c) a ligand, wherein the ligand is phosphoric acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, fumaric acid, aspartic acid, succinic acid, glutaric acid, pimecrolic acid, octanoic acid, azelaic acid, sebacic acid, maleic acid, pentenepic acid, mucoconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, tartaric acid, their salts, or combinations thereof, (d) a cationic polymer, wherein the cationic polymer includes poly(vinylimidazolium), polylysine, and poly(methacryloxyethyltrimethylammonium chloride). (polyMADQUAT), poly(diallyl dimethylammonium chloride) (polyDADMAC), poly(dimethylamine-co-epiochlorohydrin), poly[bis(2-chloroethyl)ether-alternating-1,3-bis[3-(dimethylamino)propyl]urea], copolymers of hydroxyethyl cellulose and diallyl dimethylammonium, copolymers of acrylamide and diallyl dimethylammonium, tetramethylammonium hydroxyethyl cellulose ethoxylate, copolymers of vinylpyrrolidone and tetramethylammonium dimethylaminoethyl methacrylate, copolymers of vinylpyrrolidone and tetramethylammonium vinylimidazole, terpolymers of vinylcaprolactone, vinylpyrrolidone and tetramethylammonium vinylimidazole, methylsulfate 3-methyl-1-vinylimidazole onium salt-N-vinylpyrrolidone copolymer, copolymers of vinylpyrrolidone and diallyl dimethylammonium, their salts or combinations thereof, (e) nonionic polymers as appropriate, and (f) water, The chemical-mechanical polishing composition does not contain an oxidizing agent, wherein the oxidizing agent includes potassium persulfate, cerium ammonium nitrate, peroxide, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, and combinations thereof.

2. The polishing composition of claim 1, wherein the polishing composition comprises about 0.05 wt.% to about 5 wt.% of the silicon dioxide abrasive.

3. The polishing composition of claim 1, wherein the silica abrasive is colloidal silica.

4. The polishing composition of claim 1, wherein the polishing composition has a pH of about 1 to about 7.

5. The polishing composition of claim 1, wherein the polishing composition has a pH of about 1 to about 4.

6. The polishing composition of claim 1, wherein the silicon dioxide abrasive has a zeta potential of 10 mV or higher.

7. The polishing composition of claim 1, wherein the silicon dioxide abrasive has a zeta potential of 20 mV or higher.

8. The polishing composition of claim 1, wherein the formulation is malonic acid or a salt thereof.

9. The polishing composition of claim 1, wherein the iron cation and the formulation are present in the composition in a molar ratio of 1:1 to 1:

5.

10. The polishing composition of claim 1, wherein the iron cation and the formulation are present in the composition in a molar ratio of 1:1 to 1:

3.

11. The polishing composition of claim 1, wherein the cationic polymer is poly(diallyldimethylammonium chloride) (polyDADMAC) or a salt thereof.

12. The polishing composition of claim 1, wherein the polishing composition comprises a nonionic polymer, and the nonionic polymer is polyvinylpyrrolidone.

13. A method for chemically-mechanically polishing a substrate, comprising: The invention provides a substrate comprising a carbon-based thin film, a polishing pad, and a chemical-mechanical polishing composition comprising: (a) about 0.001 wt.% to about 10 wt.% of a silicon dioxide abrasive having a positive zeta potential; (b) an iron cation, wherein the iron cation is present in the polishing composition in an amount of about 1 ppm to about 1000 ppm based on the total weight of the polishing composition; (c) a ligand, wherein the ligand is phosphoric acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, fumaric acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, maleic acid, pentenepic acid, mucoconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, tartaric acid, salts thereof, or combinations thereof; and (d) [The invention further provides the following information:] Cationic polymers, wherein the cationic polymers include poly(vinylimidazolium), polylysine, poly(methacryloxyethyltrimethylammonium chloride) (polyMADQUAT), and poly(diallyldimethylammonium chloride). (polyDADMAC), poly(dimethylamine-co-epiochlorohydrin), poly[bis(2-chloroethyl)ether-alternating-1,3-bis[3-(dimethylamino)propyl]urea], copolymers of hydroxyethyl cellulose and diallyl dimethylammonium, copolymers of acrylamide and diallyl dimethylammonium, tetramethylammonium hydroxyethyl cellulose ethoxylate, copolymers of vinylpyrrolidone and tetramethylammonium dimethylaminoethyl methacrylate, copolymers of vinylpyrrolidone and tetramethylammonium vinylimidazole, terpolymers of vinylcaprolactam, vinylpyrrolidone and tetramethylammonium vinylimidazole, methylsulfate 3-methyl-1-vinylimidazole onium salt-N-vinylpyrrolidone copolymer, copolymers of vinylpyrrolidone and diallyl dimethylammonium, their salts or combinations thereof, (e) nonionic polymers as appropriate, and (f) water, The substrate is brought into contact with the polishing pad and the chemical-mechanical polishing composition, and the polishing pad and the chemical-mechanical polishing composition are moved relative to the substrate to grind at least a portion of the substrate to polish the substrate, wherein when silicon oxide, silicon nitride, polycrystalline silicon, or titanium nitride are present on the substrate, the removal rate (Å / min) of the carbon-based thin film is greater than the removal rate (Å / min) of the silicon oxide, silicon nitride, polycrystalline silicon, or titanium nitride.

14. The method of claim 13, wherein at least a portion of the carbon-based thin film is polished at a certain removal rate (Å / min) to polish the substrate.

15. The method of claim 14, wherein the substrate further comprises silicon oxide, silicon nitride, polycrystalline silicon, titanium nitride or a combination thereof, and wherein at least a portion of the silicon oxide, silicon nitride, polycrystalline silicon or titanium nitride is polished at a certain removal rate (Å / min) to polish the substrate.

16. The method of claim 15, wherein the removal rate (Å / min) of the carbon-based thin film is at least 50 times the removal rate (Å / min) of the silicon oxide.

17. The method of claim 13, wherein the silica abrasive is colloidal silica.

18. The method of claim 17, wherein the silicon dioxide abrasive has a zeta potential of 10 mV or higher.

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