Oxidant-free slurry for ruthenium chemical mechanical polishing

Abstract

The present invention provides a chemical mechanical polishing composition comprising: (a) an abrasive having a Vickers hardness of 16 GPa or greater, and (b) a liquid carrier, wherein the polishing composition is substantially free of an oxidizing agent and wherein the polishing composition has a pH of about 0 to about 7. The present invention further provides a method of polishing a substrate, particularly a substrate comprising ruthenium, using the polishing composition.

Description

[0001] This application is a divisional application of Chinese invention patent application (Invention title: Oxidant-free slurry for ruthenium chemical mechanical polishing, application date: December 9, 2019; application number: 2019800911496). Background Technology

[0002] Compositions and methods for planarizing or polishing substrate surfaces are well known in the art. Polishing compositions (also called polishing slurries) typically contain an abrasive material in a liquid carrier and are applied to a surface by contacting the surface with a polishing pad saturated with the polishing composition. Typical abrasive materials include silicon dioxide, cerium oxide, aluminum oxide, zirconium oxide, and tin oxide. Polishing compositions are typically used in conjunction with polishing pads (e.g., polishing cloths or polishing discs). Alternatively, the abrasive material may be incorporated into the polishing pad, in addition to being suspended in the polishing composition.

[0003] In the fabrication of microelectronic devices, ruthenium is emerging as a potential candidate for next-generation liner and conductive metals due to its low resistivity, good step coverage, and high thermal stability. To our knowledge, all existing platforms providing high ruthenium removal rates utilize substrates formed by physical vapor deposition of ruthenium and polishing compositions containing strong oxidants and high abrasive particle loadings. Unfortunately, these conventional approaches introduce safety concerns, as some of the oxidants required to aid in ruthenium removal can be toxic and / or explosive. Furthermore, certain species of oxidized ruthenium (e.g., RuO4(g)) are toxic and volatile.

[0004] Furthermore, current approaches for fabricating ruthenium-based components have shifted from physical vapor deposition to chemical vapor deposition and / or atomic layer deposition, as these methods provide better uniformity of ruthenium on the substrate surface.

[0005] Therefore, there is still a need in the art for improved polishing compositions and methods for chemical mechanical polishing of ruthenium-containing substrates, which are free of oxidants to address safety concerns, but strong enough to provide adequate ruthenium removal rates. Summary of the Invention

[0006] The present invention provides a chemical mechanical polishing composition comprising, substantially comprising, or consisting of: (a) an abrasive having a Vickers hardness of 16 GPa or greater and (b) a liquid carrier, wherein the polishing composition is substantially free of oxidants and wherein the pH of the polishing composition is from about 0 to about 7.

[0007] The present invention also provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate, wherein the substrate comprises ruthenium located on a surface of the substrate; (ii) providing a polishing pad; (iii) providing a chemically mechanically polishing composition comprising (a) an abrasive having a Vickers hardness of 16 GPa or greater and (b) a liquid carrier, wherein the polishing composition is substantially free of oxidants and wherein the pH of the polishing composition is from about 0 to about 8; (iv) contacting the substrate with the polishing pad and the polishing composition; and (v) moving the polishing pad and the polishing composition relative to the substrate to abrade at least a portion of the ruthenium located on the surface of the substrate, thereby polishing the substrate.

[0008] Specifically, the present invention includes:

[0009] 1. A chemical mechanical polishing composition comprising:

[0010] (a) Abrasives with a Vickers hardness of 16 GPa or greater, and

[0011] (b) Liquid carrier,

[0012] The polishing composition is substantially free of oxidants, and the pH of the polishing composition is from about 0 to about 8.

[0013] 2. The polishing composition of item 1, wherein the pH of the polishing composition is from about 1 to about 6.

[0014] 3. The polishing composition of item 2, wherein the pH of the polishing composition is from about 2 to about 5.

[0015] 4. The polishing composition of item 1, wherein the abrasive has a Vickers hardness of 40 GPa or greater.

[0016] 5. The polishing composition of item 4, wherein the abrasive has a Vickers hardness of 50 GPa or greater.

[0017] 6. The polishing composition of item 1, wherein the abrasive comprises diamond, cubic boron nitride, α-Al2O3, or a combination thereof.

[0018] 7. The polishing composition of item 6, wherein the abrasive contains diamond.

[0019] 8. The polishing composition of item 1, wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 1% by weight.

[0020] 9. The polishing composition of item 8, wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 0.1% by weight.

[0021] 10. The polishing composition of item 9, wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 0.05% by weight.

[0022] 11. The polishing composition of item 1, wherein the abrasive has an average particle size of about 1 nm to about 1 micrometer.

[0023] 12. The polishing composition of item 11, wherein the abrasive has an average particle size of about 5 nm to about 500 nm.

[0024] 13. The polishing composition of item 12, wherein the abrasive has an average particle size of about 5 nm to about 200 nm.

[0025] 14. A method for chemically and mechanically polishing a substrate, comprising:

[0026] (i) A substrate is provided, wherein the substrate contains ruthenium located on the surface of the substrate;

[0027] (ii) Provide polishing pads;

[0028] (iii) Providing a chemical mechanical polishing composition comprising:

[0029] (a) Abrasives with a Vickers hardness of 16 GPa or greater, and

[0030] (b) Liquid carrier,

[0031] The polishing composition is substantially free of oxidants, and the pH of the polishing composition is from about 0 to about 7.

[0032] (iv) bringing the substrate into contact with the polishing pad and the polishing composition; and

[0033] (v) The polishing pad and the polishing composition are moved relative to the substrate to grind at least a portion of the ruthenium located on the surface of the substrate, thereby polishing the substrate.

[0034] 15. The method of Item 14, wherein the ruthenium further comprises carbon, oxygen, nitrogen, or a combination thereof.

[0035] 16. The method of Item 14, wherein the pH of the polishing composition is from about 1 to about 6.

[0036] 17. The method of Item 14, wherein the abrasive comprises diamond, cubic boron nitride, α-Al₂O₃, or a combination thereof.

[0037] 18. The method of Item 17, wherein the abrasive contains diamond.

[0038] 19. The method of Item 14, wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 1% by weight.

[0039] 20. The method of Item 14, wherein the average particle size of the abrasive is about 1 nm to about 1 micrometer. Detailed Implementation

[0040] The present invention provides a chemical mechanical polishing composition comprising, substantially comprising, or consisting of: (a) an abrasive having a Vickers hardness of 16 GPa or greater and (b) a liquid carrier, wherein the polishing composition is substantially free of oxidants and wherein the pH of the polishing composition is from about 0 to about 8.

[0041] Chemical mechanical polishing compositions comprise abrasives (e.g., abrasive particles) that are preferably suspended in a liquid carrier (e.g., water). The abrasives are typically in particulate form. The abrasives are formed from any suitable bulk material with a Vickers hardness of 16 GPa or greater (e.g., about 30 GPa or greater, about 40 GPa or greater, about 50 GPa or greater, about 60 GPa or greater, or about 70 GPa or greater, or about 80 GPa or greater).

[0042] Vickers hardness is a quantitative measure of a material's (i.e., the material from which it forms an abrasive) resistance to deformation. For example, cerium oxide has a Vickers hardness of about 4 GPa, zirconium oxide has a Vickers hardness of about 6 GPa, silica (quartz) has a Vickers hardness of about 10 GPa, alumina has a Vickers hardness of about 16 to about 30 GPa, cubic boron nitride has a Vickers hardness of about 50, and diamond has an estimated Vickers hardness of about 80 (see, for example, Microstructure-Property Correlations for Hard, Superhard, and Ultrahard Materials, Kanyanta, V. ed., Springer, 2016; Dubrovinsky et al., Nature, 2001, 410(6829), 653; Din et al., Mater. Chem. Phys., 1998, 53(1), 48-54; and Maschio et al., J. Eur. Ceram. Soc., 1992, 9(2), 127-132). Vickers hardness can be measured by any suitable method (such as the procedure in ASTM standard C1327-15).

[0043] In some embodiments, the abrasive has a hardness of about 5 Mohs or greater (e.g., about 5.5 Mohs or greater, about 6 Mohs or greater, about 6.5 Mohs or greater, about 7 Mohs or greater, about 7.5 Mohs or greater, or about 8 Mohs or greater). In some embodiments, the abrasive has a hardness of about 5 Mohs to about 15 Mohs, for example, about 5.5 Mohs to about 15 Mohs, about 6 Mohs to about 15 Mohs, about 6.5 Mohs to about 15 Mohs, about 7 Mohs to about 15 Mohs, about 7.5 Mohs to about 15 Mohs, or about 8 Mohs to about 15 Mohs. In some embodiments, the abrasive has a hardness of about 8 Mohs to about 15 Mohs. Mohs hardness is a qualitative measure of the relative ability of a material (i.e., the material from which an abrasive is formed) to scratch another material.

[0044] In some embodiments, the abrasive comprises diamond, cubic boron nitride, alumina (Al₂O₃), silicon carbide (SiC), titanium oxide (TiO₂), tungsten carbide (WC), zirconium oxide (ZrO₂), boron carbide (B₄C), tantalum carbide (TaC), titanium carbide (TiC), or combinations thereof. Diamond can be any suitable form of diamond. For example, the term "diamond" includes particles (e.g., nanoparticles) of natural or synthetic single-crystal diamond, polycrystalline diamond, ultra-detonation diamond, or combinations thereof. As used herein, "cubic boron nitride" refers to the zincblende structure of boron nitride, which has a similar crystalline morphology to diamond. Any suitable alumina can be used, such as α-alumina (α-Al₂O₃).

[0045] Abrasives can have any suitable particle size. As used herein, the particle size of an abrasive particle is the diameter of the smallest sphere surrounding the particle. The average particle size of the abrasive particles can be about 1 nm or larger, for example, about 5 nm or larger, about 10 nm or larger, about 15 nm or larger, about 20 nm or larger, about 30 nm or larger, about 40 nm or larger, or about 50 nm or larger. Alternatively or additionally, the average particle size of the abrasive particles can be about 10 micrometers or smaller, for example, about 1 micrometer or smaller, about 500 nm or smaller, about 400 nm or smaller, about 300 nm or smaller, about 200 nm or smaller, about 100 nm or smaller, or about 50 nm or smaller. Thus, the average particle size of the abrasive particles can be within the range defined by any two of the foregoing endpoints. For example, the average particle size of the abrasive particles can be from about 1 nm to about 10 micrometers, such as from about 1 nm to about 1 micrometer, from about 1 nm to about 500 nm, from about 1 nm to about 250 nm, from about 1 nm to about 200 nm, from about 1 nm to about 100 nm, from about 1 nm to about 50 nm, from about 5 nm to about 1 micrometer, from about 5 nm to about 500 nm, from about 5 nm to about 250 nm, from about 5 nm to about 200 nm, from about 5 nm to about 100 nm, or from about 5 nm to about 50 nm. In some embodiments, the average particle size of the abrasive particles is from about 1 nm to about 1 micrometer. In some embodiments, the average particle size of the abrasive particles is from about 5 nm to about 500 nm.

[0046] The abrasive may be treated (e.g., cationic or anionic) or untreated. In some embodiments, the abrasive is treated (e.g., as described in US7,265,055). As used herein, a treated abrasive may be surface-treated or doped with the corresponding cationic or anionic molecules or atoms. Thus, at a pH of about 4, the zeta potential of the abrasive may be about -100 mV or greater, for example, about -75 mV or greater, about -50 mV or greater, about -25 mV or greater, or about 0 mV or greater. Alternatively or additionally, at a pH of about 4, the zeta potential of the abrasive may be about +100 mV or less, for example, about +75 mV or less, about +50 mV or less, about +25 mV or less, or about 0 mV or less. Thus, the zeta potential of the abrasive may be within a range defined by any two of the foregoing endpoints. For example, at a pH of about 4, the zeta potential of the abrasive can be about -100mV to about +100mV, such as about -75mV to about +75mV, about -50mV to about +50mV, about -100mV to about 0mV, or about 0mV to about +100mV.

[0047] Any suitable amount of abrasive may be present in the polishing composition. In some embodiments, the abrasive is present in the polishing composition at a concentration of about 0.0005% by weight or greater, such as about 0.001% by weight or greater, about 0.0025% by weight or greater, about 0.005% by weight or greater, about 0.01% by weight or greater, about 0.025% by weight or greater, or about 0.05% by weight or greater. More typically, the abrasive is present in the polishing composition at a concentration of about 0.001% by weight or greater, such as about 0.0025% by weight or greater, about 0.005% by weight or greater, about 0.01% by weight or greater, about 0.025% by weight or greater, or about 0.05% by weight or greater. Alternatively or additionally, the abrasive is present in the polishing composition at a concentration of about 30% by weight or less, such as about 20% by weight or less, about 10% by weight or less, about 5% by weight or less, about 1% by weight or less, about 0.5% by weight or less, about 0.1% by weight or less, or about 0.05% by weight or less. More typically, the abrasive is present in the polishing composition at a concentration of about 1% by weight or less, such as about 0.5% by weight or less, about 0.1% by weight or less, or about 0.05% by weight or less. Therefore, the abrasive can be present in the polishing composition within the range defined by any two of the foregoing endpoints. For example, the abrasive can be from about 0.0005% by weight to about 10% by weight, such as about 0.001% by weight to about 10% by weight, about 0.001% by weight to about 1% by weight, about 0.001% by weight to about 0.5% by weight, about 0.001% by weight to about 0.1% by weight, about 0.001% by weight to about 0.05% by weight, about 0.005% by weight to about 10% by weight, about 0.005% by weight to about 1% by weight, about 0.005% by weight to about 0.5% by weight, about 0.005% by weight to about 0.1% by weight, about 0.005% by weight. The abrasive is present in the polishing composition at a concentration of about 0.05 wt%, about 0.01 wt% to about 10 wt%, about 0.01 wt% to about 1 wt%, about 0.01 wt% to about 0.5 wt%, about 0.01 wt% to about 0.1 wt%, about 0.01 wt% to about 0.05 wt%, about 0.05 wt% to about 10 wt%, about 0.05 wt% to about 1 wt%, about 0.05 wt% to about 0.5 wt%, about 0.05 wt% to about 0.1 wt%, or about 0.05 wt% to about 0.05 wt%. In some embodiments, the abrasive is present in the polishing composition at a concentration of about 0.001 wt% to about 1 wt%.

[0048] The polishing compositions described herein are substantially free of oxidants. As used herein, the phrase "substantially free of oxidants" means that the composition contains less than about 1 ppm of an oxidant (e.g., less than about 100 ppb, less than about 10 ppb, less than about 1 ppb, less than about 100 ppt, less than about 10 ppt, or less than about 1 ppt). In some embodiments, the polishing composition is free of oxidants (i.e., below detectable levels). As used herein, the phrase "oxidant" means any chemical substance other than ambient air capable of oxidizing ruthenium above the +4 oxidation state. Examples of such oxidants include, but are not limited to, peroxides (e.g., H2O2), periodic acid, potassium peroxymonosulfate (potassium peroxymonosulfate preparation, oxone), bromate, bromate, hypobromite, chlorate, chlorite, hypochlorite, perchlorate, iodate, hypoiodide, periodate, cerium(IV) salts, permanganate, silver(III) salts, peracetic acid, organo-halo-oxy compounds, monoperoxysulfate, monoperoxysulfite, monoperoxythiosulfate, monoperoxyphosphate, monoperoxypyrophosphate, and monoperoxydiphosphate.

[0049] Typically, the pH of a chemical mechanical polishing composition is about 8 or less, for example, about 7 or less, such as about 6.5 or less, about 6 or less, about 5.5 or less, about 5 or less, about 4.5 or less, about 4 or less, about 3.5 or less, about 3 or less, about 2.5 or less, about 2 or less, about 1.5 or less, about 1 or less, or about 0.5 or less. Alternatively or additionally, the pH of a chemical mechanical polishing composition may be about 0 or greater, for example, about 0.5 or greater, about 1 or greater, about 1.5 or greater, about 2 or greater, about 2.5 or greater, about 3 or greater, about 3.5 or greater, about 4 or greater, or about 4.5 or greater. Therefore, the pH of a chemical mechanical polishing composition can be within the range defined by any two of the foregoing endpoints. For example, the pH of the polishing composition may be about 6 to about 7, about 5.5 to about 6.5, about 5 to about 6, about 4.5 to about 5.5, about 4 to about 5, about 3.5 to about 4.5, about 3 to about 4, about 2.5 to about 3.5, about 2 to about 3, about 1.5 to about 2.5, about 1 to about 2, about 0.5 to about 1.5, or about 0 to about 1. In some embodiments, the pH of the polishing composition is about 0 to about 7, for example, about 0 to about 6, about 0 to about 5, about 0 to about 4, about 0 to about 3, about 0 to about 2, about 1 to about 7, about 1 to about 6, about 1 to about 5, about 1 to about 4, about 1 to about 3, about 2 to about 7, about 2 to about 6, about 2 to about 5, about 2 to about 4, about 3 to about 7, about 3 to about 6, or about 3 to about 5. In some embodiments, the pH of the polishing composition is about 2 to about 5, for example, about 2, about 3, about 4, or about 5.

[0050] The chemical mechanical polishing composition may contain one or more compounds capable of adjusting (i.e., modifying) the pH of the polishing composition (i.e., pH adjusting compounds). The pH of the 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.

[0051] Compounds capable of adjusting and buffering pH can be selected from ammonium salts, alkali metal salts, carboxylic acids, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, organic acids (e.g., acetic acid), organic bases (e.g., amines), and combinations thereof. In some embodiments, the pH is adjusted or buffered using organic acids (e.g., acetic acid and / or potassium acetate). For example, the buffer can be an acidic chemical reagent, a basic chemical reagent, a neutral chemical reagent, or a combination thereof. An exemplary list of buffers includes nitric acid, sulfuric acid, phosphoric acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, maleic acid, acetic acid, ammonium hydroxide, phosphates, sulfates, acetates, malonates, oxalates, borates, ammonium salts, amines, polyols (e.g., trisbase), amino acids, and the like.

[0052] The polishing composition includes a liquid carrier. The liquid carrier contains water (e.g., deionized water) and optionally one or more water-miscible organic solvents. Examples of usable organic solvents include: alcohols, such as allyl alcohol, isopropanol, ethanol, 1-propanol, methanol, 1-hexanol, and the like; aldehydes, such as acetaldehyde and the like; ketones, such as acetone, diacetone alcohol, methyl ethyl ketone, and the like; esters, such as ethyl formate, propyl formate, ethyl acetate, methyl acetate, methyl lactate, butyl lactate, ethyl lactate, and the like; ethers, including sulfoxides, such as dimethyl sulfoxide (DMSO), tetrahydrofuran, etc. Alkanes, diethylene glycol dimethyl ether and their analogues; amides, such as N,N-dimethylformamide, dimethylimidazolium ketone, N-methylpyrrolidone and their analogues; polyols and their derivatives, such as ethylene glycol, glycerol, diethylene glycol monomethyl ether and their analogues; and nitrogen-containing organic compounds, such as acetonitrile, pentylamine, isopropylamine, imidazole, dimethylamine and their analogues. Preferably, the liquid carrier is only water, i.e., no organic solvent is present.

[0053] The polishing composition optionally further comprises one or more additives. Illustrative additives include buffers, depression control agents, chelating agents, biocides, scale inhibitors, corrosion inhibitors, dispersants, etc. In some embodiments, the polishing composition further comprises buffers, depression control agents, chelating agents, biocides, corrosion inhibitors, dispersants, or combinations thereof. In some embodiments, the polishing composition further comprises buffers, depression control agents, and biocides. In other embodiments, the polishing composition further comprises buffers and biocides.

[0054] In some embodiments, the chemical mechanical polishing composition further comprises a pitting control agent. As used herein, the phrase "pitting control agent" refers to any chemical agent that, when the ruthenium overlay is removed, reduces the loss of ruthenium within the circuit traces compared to a chemical mechanical polishing composition without a pitting control agent. Pitting and corrosion can be determined using any suitable technique. Examples of suitable techniques for determining pitting and corrosion include scanning electron microscopy, stylus profiling, and atomic force microscopy. Atomic force microscopy can be performed using a Dimension Atomic Force Profiler (AFP™) from Veeco (Plainview, NY).

[0055] In some embodiments, the chemimechanical composition comprises a biocide. When present, the biocide can be any suitable biocide and can be present in any suitable amount in the polishing composition. An exemplary biocide is an isothiazolinone biocide. The polishing composition may contain a biocide of about 1 ppm to about 200 ppm, for example, about 10 ppm to about 200 ppm, about 10 ppm to about 150 ppm, about 20 ppm to about 150 ppm, about 50 ppm to about 150 ppm, about 1 ppm to about 150 ppm, or about 1 ppm to about 100 ppm.

[0056] Polishing compositions can be produced by 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. As used herein, the term "component" includes individual components (e.g., abrasives, buffers, depression control agents, chelating agents, biocides, scale inhibitors, corrosion inhibitors, dispersants, etc.) as well as any combination of components (e.g., abrasives, buffers, depression control agents, chelating agents, biocides, scale inhibitors, corrosion inhibitors, dispersants, etc.).

[0057] In some embodiments, the chemical mechanical polishing (CMP) composition is stored in a single container. In other embodiments, the CMP composition is stored in two or more containers such that the CMP composition is mixed at or near the use location. To mix the components contained in two or more storage devices at or near the use location to produce a polishing composition, the storage devices are typically provided with one or more flow lines leading from each storage device to the use location of the polishing composition (e.g., a pressure plate, polishing pad, or substrate surface). As used herein, the term "use location" refers to the location 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 a separate storage container to the use location of the component stored therein. Flow lines may each lead directly to the use location, or two or more flow lines may be merged at any location into a single flow line leading to the use location. Furthermore, any flow line (e.g., a single flow line or a merged flow line) may first lead to one or more other devices (e.g., a pumping device, a measuring device, a mixing device, etc.) before reaching the use location of the component.

[0058] The components of the polishing composition can be delivered to the application location independently (e.g., delivered to a substrate surface and then mixed during the polishing process), or one or more of the components can be combined before being delivered to the application location (e.g., shortly before or just before delivery to the application location). If the components are combined about 5 minutes or less before being added to the pressure plate 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 simultaneously with the components being delivered to the application location, then the components are combined "just before delivery to the application location". If the components are combined within 5 minutes at the application location, such as within 1 minute at the application location, then the components are also combined "just before delivery to the application location".

[0059] When two or more components of a polishing composition are combined before reaching the application location, the components can be combined in a flow line and delivered to the application location without the use of a mixing device. Alternatively, one or more of the flow lines can be introduced into a mixing device to facilitate the combination of two or more components. Any suitable mixing device can be used. For example, the mixing device can be a nozzle or jet (e.g., a high-pressure nozzle or jet) through which two or more of the components flow. Alternatively, the mixing device can 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 for delivery to the application location, either directly or via other components of the device (e.g., via one or more flow lines). Furthermore, the mixing device may comprise 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 well known in the art and include stirrers, mixers, agitators, paddled baffles, gas sparger systems, vibrators, etc.

[0060] The polishing composition may also be provided as a concentrate, intended to be diluted with an appropriate amount of water prior to use. In such an embodiment, the polishing composition concentrate contains an amount of polishing composition components 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 described above for each component. For example, the abrasive and any 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 described above for each component, such that, when the concentrate is diluted with equal volumes of water (e.g., with two, three, or four equal volumes of water, respectively), each component will be present in the polishing composition in an amount within the range described above for each component.

[0061] The present invention also provides a method for polishing a substrate using the polishing composition described herein. The method for polishing a substrate includes: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing the aforementioned chemical mechanical polishing composition; (iv) contacting the substrate with the polishing pad and the chemical mechanical polishing composition; and (v) moving the polishing pad and the chemical mechanical polishing composition relative to the substrate to abrade at least a portion of the substrate surface thereby polishing the substrate.

[0062] Specifically, the present invention further provides a method for chemically mechanically polishing a substrate, comprising: (i) providing a substrate, wherein the substrate comprises ruthenium located on the surface of the substrate; (ii) providing a polishing pad; (iii) providing a chemically mechanically polishing composition comprising: (a) an abrasive having a Vickers hardness of 20 GPa or greater and (b) a liquid carrier, wherein the polishing composition is substantially free of oxidants and wherein the pH of the polishing composition is from about 0 to about 7; (iv) contacting the substrate with the polishing pad and the polishing composition; and (v) moving the polishing pad and the polishing composition relative to the substrate to abrade at least a portion of the ruthenium located on the surface of the substrate, thereby polishing the substrate.

[0063] Chemical mechanical polishing compositions can be used to polish any suitable substrate and are particularly suitable for polishing substrates comprising at least one layer (typically a surface layer) of a dielectric material (e.g., a low-k dielectric material). Suitable substrates include wafers used in the semiconductor industry. Wafers typically comprise or are composed of, for example, metals, metal oxides, metal nitrides, metal carbides, metal composites, metal alloys, low-k dielectric materials, or combinations thereof. The method of the present invention is particularly suitable for polishing substrates containing ruthenium.

[0064] In a preferred embodiment, the substrate comprises ruthenium (e.g., Ru). 0 Ruthenium can be applied to a substrate surface by any suitable method. For example, ruthenium can be applied to a substrate surface using physical vapor deposition (“PVD”), chemical vapor deposition (“CVD”), atomic layer deposition (“ALD”), electrochemical plating (“ECP”), or any combination thereof. In some embodiments, ruthenium is applied to the substrate surface via CVD, ECP, and / or ALD.

[0065] In embodiments where ruthenium further comprises oxygen, ruthenium can be any suitable ruthenium species in any suitable oxidation state. For example, ruthenium can be Ru(OH)₂. + Ru 3+ , Ru(OH)3·H2O, RuO2·2H2O, Ru2O, H2RuO5, Ru4(OH) 12 4+ Ru(OH)2 2+ Or a combination thereof. In some embodiments, the substrate comprises Ru 0 Ru(OH)2 + Ru 3+ , Ru(OH)3·H2O, RuO2·2H2O, Ru4(OH) 12 4+ Ru(OH)2 2+ Or a combination thereof.

[0066] When a ruthenium-containing substrate is polished according to the method of the present invention, the chemical mechanical polishing composition of the present invention desirously exhibits a high removal rate. For example, when a ruthenium-containing silicon wafer is polished according to an embodiment of the present invention, the polishing composition desirously exhibits a ruthenium removal rate of about 100 Å / min or higher, such as 150 Å / min or higher, about 200 Å / min or higher, about 250 Å / min or higher, about 300 Å / min or higher, about 350 Å / min or higher, about 400 Å / min or higher, about 450 Å / min or higher, or about 500 Å / min or higher.

[0067] The chemical mechanical polishing composition and method of the present invention are particularly suitable for use in conjunction with a chemical mechanical polishing apparatus. Typically, the apparatus includes: a pressure plate that is in motion during use and has a speed generated by track, linear, or circular motion; a polishing pad that contacts the pressure plate and moves with the pressure plate during motion; and a carrier that holds a substrate to be polished by contacting the surface of the polishing pad and moving it relative to the surface of the polishing pad. Polishing of the substrate is performed by the following steps: 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 grind at least a portion of the substrate to polish it.

[0068] The substrate can be polished using any suitable polishing pad (e.g., polishing surface) with a chemical mechanical polishing composition. Suitable polishing pads include, for example, woven and non-woven polishing pads. Furthermore, suitable polishing pads may contain any suitable polymer with different densities, hardness, thickness, compressibility, compression resilience, and compressive modulus. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbons, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene, their co-formations, and mixtures thereof. Soft polyurethane polishing pads are particularly suitable for use with the polishing method of the present invention. Typical pads include, but are not limited to, SURFIN™ 000, SURFIN™ SSW1, SPM3100 (available from, for example, Emines Technologies), POLITEX™, and Fujibo POLYPAS™ 27. Particularly preferred polishing pads are the EPIC™ D100 pad and NEXPLANAR, available from Cabot Microelectronics. TM The E6088 pad and the IC1010™ pad are available from Dow Chemical Company.

[0069] Desiredly, chemical mechanical polishing (CMP) apparatuses further include in-situ polishing endpoint detection systems, many of which are known in the art. 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 art. Such methods are described, for example, in U.S. Patents 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. Desiredly, inspection or monitoring of the progress of the polishing process on the substrate being polished enables the determination of the polishing endpoint, i.e., determining when to terminate the polishing process on a particular substrate.

[0070] The present invention is further illustrated by the following embodiments.

[0071] Implementation

[0072] (1) A chemical mechanical polishing composition is provided in embodiment (1) comprising: (a) an abrasive having a Vickers hardness of 16 GPa or greater and (b) a liquid carrier, wherein the polishing composition is substantially free of oxidants and wherein the pH of the polishing composition is from about 0 to about 8.

[0073] (2) In embodiment (2), the polishing composition of embodiment (1) is provided, wherein the pH of the polishing composition is from about 1 to about 6.

[0074] (3) In embodiment (3), the polishing composition of embodiment (2) is provided, wherein the pH of the polishing composition is about 2 to about 5.

[0075] (4) In embodiment (4), a polishing composition of any one of embodiments (1) to (3) is provided, wherein the abrasive has a Vickers hardness of 40 GPa or greater.

[0076] (5) The polishing composition of embodiment (4) is provided in embodiment (5), wherein the Vickers hardness of the abrasive is 50 GPa or greater.

[0077] (6) In embodiment (6), a polishing composition of any one of embodiments (1) to (5) is provided, wherein the abrasive comprises diamond, cubic boron nitride, α-Al2O3 or a combination thereof.

[0078] (7) In embodiment (7), the polishing composition of embodiment (6) is provided, wherein the abrasive contains diamond.

[0079] (8) In embodiment (8), a polishing composition of any one of embodiments (1) to (7) is provided, wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 1% by weight.

[0080] (9) In embodiment (9), the polishing composition of embodiment (8) is provided, wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 0.1% by weight.

[0081] (10) In embodiment (10), the polishing composition of embodiment (9) is provided, wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 0.05% by weight.

[0082] (11) In embodiment (11), a polishing composition of any one of embodiments (1) to (10) is provided, wherein the average particle size of the abrasive is about 1 nm to about 1 micrometer.

[0083] (12) The polishing composition of embodiment (11) is provided in embodiment (12), wherein the average particle size of the abrasive is about 5 nm to about 500 nm.

[0084] (13) The polishing composition of embodiment (12) is provided in embodiment (13), wherein the average particle size of the abrasive is about 5 nm to about 200 nm.

[0085] (14) In embodiment (14), a polishing composition of any one of embodiments (1) to (13) is provided, wherein the polishing composition further comprises a buffer, a depression control agent, a chelating agent, a biocide, a corrosion inhibitor, a dispersant, or a combination thereof.

[0086] (15) In embodiment (15), a polishing composition of any one of embodiments (1) to (14) is provided, wherein the polishing composition further comprises a buffer, a depression control agent and a biocide.

[0087] (16) In embodiment (16), a polishing composition of any one of embodiments (1) to (14) is provided, wherein the polishing composition further comprises a buffer and a biocide.

[0088] (17) A method of providing a chemical mechanical polishing substrate in embodiment (17) includes: (i) providing a substrate, wherein the substrate contains ruthenium on a surface of the substrate; (ii) providing a polishing pad; (iii) providing a chemical mechanical polishing composition comprising: (a) an abrasive having a Vickers hardness of 20 GPa or greater, and (b) a liquid carrier, wherein the polishing composition is substantially free of oxidants and wherein the pH of the polishing composition is from about 0 to about 7; (iv) contacting the substrate with the polishing pad and the polishing composition; and (v) moving the polishing pad and the polishing composition relative to the substrate to abrade at least a portion of the ruthenium on the surface of the substrate, thereby polishing the substrate.

[0089] (18) The method of embodiment (17) is provided in embodiment (18), wherein the ruthenium is applied to the surface of the substrate by chemical vapor deposition.

[0090] (19) The method of embodiment (17) is provided in embodiment (19), wherein the ruthenium is applied to the surface of the substrate by atomic layer deposition.

[0091] (20) The method of any one of embodiments (17) to (19) is provided in embodiment (20), wherein the ruthenium further comprises carbon, oxygen, nitrogen or a combination thereof.

[0092] (21) The method of any one of embodiments (17) to (20) is provided in embodiment (21), wherein the pH of the polishing composition is about 1 to about 6.

[0093] (22) The method of embodiment (21) is provided in embodiment (22), wherein the pH of the polishing composition is about 2 to about 5.

[0094] (23) The method of any one of embodiments (17) to (22) is provided in embodiment (23), wherein the Vickers hardness of the abrasive is 40 GPa or greater.

[0095] (24) The method of embodiment (23) is provided in embodiment (24), wherein the Vickers hardness of the abrasive is 50 GPa or greater.

[0096] (25) The method of any one of embodiments (17) to (24) is provided in embodiment (25), wherein the abrasive comprises diamond, cubic boron nitride, α-Al2O3 or a combination thereof.

[0097] (26) The method of embodiment (25) is provided in embodiment (26), wherein the abrasive contains diamond.

[0098] (27) The method of any one of embodiments (17) to (26) is provided in embodiment (27), wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 1% by weight.

[0099] (28) The method of embodiment (27) is provided in embodiment (28), wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 0.1% by weight.

[0100] (29) The method of embodiment (28) is provided in embodiment (29), wherein the abrasive is present in the polishing composition at a concentration of about 0.001% by weight to about 0.05% by weight.

[0101] (30) The method of any one of embodiments (17) to (29) is provided in embodiment (30), wherein the average particle size of the abrasive is about 1 nm to about 1 micrometer.

[0102] (31) The method of embodiment (30) is provided in embodiment (31), wherein the average particle size of the abrasive is about 5 nm to about 500 nm.

[0103] (32) The method of embodiment (31) is provided in embodiment (32), wherein the average particle size of the abrasive is about 5 nm to about 200 nm.

[0104] (33) The method of any one of embodiments (17) to (32) is provided in embodiment (33), wherein the polishing composition further comprises a buffer, a depression control agent, a chelating agent, a biocide, a corrosion inhibitor, a dispersant or a combination thereof.

[0105] (34) The method of any one of embodiments (17) to (33) is provided in embodiment (34), wherein the polishing composition further comprises a buffer, a depression control agent and a biocide.

[0106] (35) The method of any one of embodiments (17) to (33) is provided in embodiment (35), wherein the polishing composition further comprises a buffer and a biocide.

[0107] These examples further illustrate the invention, but should not be construed as limiting its scope in any way.

[0108] Example

[0109] The following abbreviations are used throughout the embodiments: removal rate (RR); physical vapor deposition (PVD); chemical vapor deposition (CVD); atomic layer deposition (ALD); ruthenium (Ru); nano-diamond (ND); cubic boron nitride (cBN); α-Al2O3 (AA); potassium acetate (AcOK); and tetraethyl orthosilicate (TEOS).

[0110] The following embodiments further illustrate the invention, but should not be construed as limiting its scope in any way.

[0111] Example 1

[0112] This embodiment demonstrates the effect of ruthenium deposition method on ruthenium removal rate, as shown by a comparative polishing slurry comprising surface-coated alumina and hydrogen peroxide.

[0113] At pH 8.4, a single substrate (i.e., a 2×2-inch coupon wafer) containing a ruthenium coating deposited by PVD (“Substrate 1A”) and CVD (“Substrate 1B”) was polished with a composition containing 1% by weight hydrogen peroxide and Al2O3 particles coated with a homopolymer of 2-acrylamido-methyl-1-propanesulfonic acid (AMPS).

[0114] On a Logitech 2 benchtop polishing machine, substrates were polished using Fujibo pads trimmed with the commercially labeled A82 (3M, St. Paul, MN) product at a downpressure of 1.5 PSI (10.3 kPa). Logitech polishing parameters were as follows: head speed = 93 rpm, platen speed = 87 rpm, total flow rate = 150 mL / min. The removal rate was calculated by subtracting the final thickness from the initial thickness using a spectroscopic ellipsometry to measure the film thickness. The ruthenium removal rate was measured after polishing, and the results are shown in Table 1.

[0115] Table 1: Ruthenium removal rate as a function of ruthenium deposition method

[0116]

[0117] As clearly shown in Table 1, the ruthenium removal rate of substrate 1A prepared by PVD is more efficient than that of substrate 1B prepared by CVD. These results indicate that the polishing composition containing the abrasive and oxidant can provide sufficient ruthenium removal for substrates prepared by PVD, but insufficient ruthenium removal for substrates prepared by CVD.

[0118] Example 2

[0119] This example demonstrates the effects of oxidant, abrasive, and pH on the ruthenium removal rate of a substrate containing CVD-deposited ruthenium.

[0120] Individual substrates (i.e., 2×2-inch sample wafers) containing CVD-deposited ruthenium coatings were polished using twelve (12) different polishing compositions (i.e., polishing compositions 2A-2L) (Table 2). Each polishing composition contained abrasives, oxidants, and additives of the types and amounts described in Table 2, and each polishing composition had the pH described in Table 2. The substrates were polished using Fujibo pads trimmed with the commercially labeled A82 (3M, St. Paul, MN) at a pressure of 1.5 PSI (10.3 kPa) on a Logitech 2 benchtop polishing machine. The Logitech polishing parameters were as follows: head speed = 93 rpm, platen speed = 87 rpm, total flow rate = 150 mL / min. The removal rate was calculated by measuring the film thickness using a spectroelometric ellipsometry and subtracting the final thickness from the initial thickness. The ruthenium removal rate was determined after polishing, and the results are shown in Table 2.

[0121] Table 2: Ruthenium removal rate as a function of oxidant, abrasive, and pH

[0122]

[0123] As clearly shown in Table 2, the polishing compositions of the present invention 2K and 2L (which do not contain an oxidant at pH 7 and 4) exhibit higher ruthenium removal rates compared to the comparative polishing compositions 2A-2C and 2E-2H (which contain an oxidant at pH 4, 7 or 10 or do not contain an oxidant at pH 10).

[0124] At similar pH values, the polishing compositions 2K and 2L of the present invention (containing diamond as an abrasive and free of oxidants) are superior to the comparative polishing compositions 2F and 2G (containing diamond as an abrasive and containing oxidants). Furthermore, comparative polishing composition 2A and the polishing compositions 2K and 2L of the present invention, with pH values ​​of 10, 7, and 4, respectively, demonstrate that as the pH decreases, the removal rate of the polishing composition containing hard abrasives (such as diamond) and free of oxidants increases. These results indicate that when using CVD deposition of ruthenium capping, polishing compositions containing hard abrasives (e.g., diamond), free of oxidants, and with a pH of 7 or lower are more effective in ruthenium removal than polishing compositions containing hard abrasives (e.g., diamond), containing oxidants, and / or with a pH greater than 7.

[0125] Example 3

[0126] This embodiment demonstrates the effect of abrasive on the ruthenium removal rate for a substrate containing ruthenium deposited by CVD.

[0127] Individual substrates (i.e., 2×2-inch sample wafers) containing CVD-deposited ruthenium coatings were polished using nine (9) different polishing compositions (i.e., polishing compositions 3A to 3I) (Table 3). Each polishing composition contained the abrasive as described in Table 3 and 100 ppm AcOK, and each had a pH of 4. None of the polishing compositions contained an oxidant. The substrates were polished as follows: on a Logitech 2 benchtop polisher, at a pressure of 1.5 PSI (10.3 kPa), using an M2000® pad (Cabot Microelectronics Corporation, Aurora, IL), and dressed with an A165 dresser (3M, St. Paul, MN). The Logitech polishing parameters were as follows: head speed = 93 rpm, platen speed = 87 rpm, total flow rate = 100 mL / min. The removal rate was calculated by measuring the film thickness using a spectroeltrometer and subtracting the final thickness from the initial thickness. After polishing, the ruthenium removal rate was determined, and the results are shown in Table 3.

[0128] Table 3: Ruthenium removal rate as a function of abrasive.

[0129]

[0130] As clearly shown in Table 3, the comparative polishing compositions 3B to 3E containing surface-coated abrasives exhibited low ruthenium removal rates when using CVD-deposited ruthenium capping. These results indicate that, in the absence of an oxidant, surface-coated abrasives are insufficient for ruthenium removal when using CVD-deposited ruthenium capping.

[0131] Furthermore, the results shown in Table 3 indicate that the polishing compositions of the present invention, 3F to 3I (containing α-Al₂O₃, cBN, or ND), exhibit higher ruthenium removal rates compared to the comparative polishing compositions 3A to 3E (which are softer abrasives with a Vickers hardness of less than 20 GPa). Table 3 also shows that the polishing compositions of the present invention (see polishing compositions 3H and 3I) containing the hardest abrasives (i.e., cBN and ND) are the most effective in ruthenium removal. These results suggest that when using CVD deposition of ruthenium coatings, polishing compositions containing hard abrasives such as α-Al₂O₃, cBN, or ND are more effective in ruthenium removal than polishing compositions containing surface-coated abrasives.

[0132] Example 4

[0133] This embodiment demonstrates the effect of abrasive and pH on the ruthenium removal rate for a substrate containing ruthenium deposited by CVD.

[0134] Individual substrates (i.e., 2×2-inch sample wafers) containing CVD-deposited ruthenium coatings were polished using six (6) different polishing compositions (i.e., polishing compositions 4A-4F) (Table 4). Each polishing composition contained the type and amount of abrasive described in Table 4, and each polishing composition had the pH described in Table 4. Each polishing composition contained 100 ppm AcOK as an additive, except for comparative polishing composition 4A, which did not contain any AcOK or other additives. None of the polishing compositions contained oxidants. M2000 dressed with an A165 dresser was used on a Logitech 2 benchtop polishing machine at a downpressure of 1.5 PSI (10.3 kPa). ® The substrate was polished. Logitech polishing parameters were as follows: head speed = 93 rpm, platen speed = 87 rpm, total flow rate = 100 mL / min. The removal rate was calculated by measuring the film thickness using a spectroeltrometer and subtracting the final thickness from the initial thickness. After polishing, the ruthenium removal rate was measured, and the results are shown in Table 4.

[0135] Table 4: Ruthenium removal rate as a function of abrasive and pH

[0136]

[0137] As clearly shown in Table 4, the polishing compositions 4B-4F of the present invention, containing ND as an abrasive, exhibit higher ruthenium removal rates than the comparative polishing composition 4A, which contains surface-coated α-alumina. These results indicate that, when using CVD deposition of ruthenium coatings, polishing compositions containing hard abrasives such as diamond provide more efficient ruthenium removal than polishing compositions containing surface-coated α-Al₂O₃ abrasives.

[0138] Furthermore, the results shown in Table 4 indicate that the ruthenium removal rate increases as the pH of the polishing composition decreases (see, for example, polishing compositions 4C to 4E), and that the ruthenium removal rate increases as the concentration of the abrasive increases (see, for example, polishing compositions 4A, 4C and 4F).

[0139] All references cited in this article (including publications, patent applications and patents) are incorporated herein by reference as if each reference were individually and specifically cited for reference and as fully described herein.

[0140] The terms “a,” “an,” “the,” and “at least one,” and similar designations used in describing the scope of the invention (particularly the scope of the appended claims) should be understood to include both singular and plural forms, unless otherwise stated herein or the context clearly contradicts. The term “at least one” (e.g., “at least one of A and B”) following a list of one or more items is interpreted as meaning one of the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise stated herein or the context clearly contradicts. The terms “comprising,” “having,” “including,” and “containing” should be understood as open-ended terms (i.e., meaning “including, but not limited to”), unless otherwise stated. The enumeration of numerical ranges herein is merely a shorthand method of individually referring to each independent value falling within that range, unless otherwise stated herein, and each independent value is introduced in the specification as if it were individually enumerated herein. All methods described herein can be performed in any suitable order, unless otherwise stated herein or clearly contradicted by the context. The use of any and all instances or exemplary language (e.g., "for example") provided herein is for the purpose of better illustrating the invention and not for limiting the scope of the invention, unless otherwise stated. No language in the specification should be construed as indicating that any non-claimed element is necessary for the practice of the invention.

[0141] Preferred embodiments of the invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors encourage those skilled in the art to adopt such variations appropriately, and the inventors encourage the invention to be practiced in ways different from those specifically described herein. Therefore, the invention includes all modifications and equivalents of the subject matter listed in the appended claims as permitted by applicable law. Furthermore, the invention covers any combination of the foregoing elements in all possible variations, unless otherwise stated herein or clearly contradicted by the context.

Claims

1. A method for chemically and mechanically polishing a substrate, comprising: (i) A substrate is provided, wherein the substrate contains ruthenium located on the surface of the substrate; (ii) Provide polishing pads; (iii) Providing a chemical mechanical polishing composition comprising the following: (a) An abrasive containing diamond, wherein the diamond has an average particle size of 5 nm to 100 nm. (b) Liquid carrier, and The polishing composition is substantially free of oxidants, and the pH of the polishing composition is 3 to 5. (iv) bringing the substrate into contact with the polishing pad and the polishing composition; and (v) The polishing pad and the polishing composition are moved relative to the substrate to grind at least a portion of the ruthenium located on the surface of the substrate, thereby polishing the substrate.

2. The method of claim 1, wherein, The ruthenium further comprises carbon, oxygen, nitrogen, or combinations thereof.

3. The method of claim 1, wherein, The pH of the polishing composition is 3.5 to 4.

5.

4. The method according to claim 1, wherein, The abrasive is present in the polishing composition at a concentration of 0.001% to 1% by weight.

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