Cmp composition and method of removing ruthenium

Abstract

This disclosure provides novel corrosion control chemicals for ruthenium (Ru) chemical mechanical polishing (CMP) processes. More specifically, this disclosure provides improved CMP slurry chemicals and CMP processes for planarizing ruthenium surfaces. In the CMP processes disclosed herein, a ruthenium surface (e.g., an etched ruthenium surface) is exposed to a CMP slurry comprising: a halogenating agent that reacts with the ruthenium surface to produce a ruthenium halide surface, and a ligand for ligand-assisted reaction to dissolve the ruthenium halide surface. The amount of the halogenating agent and the ligand in the CMP slurry can be controlled, resulting in a diffusion-limited etching process that provides improved post-etched surface morphology while offering a high material removal rate.

Description

Technical Field

[0001] This disclosure relates to the manufacture of semiconductor devices, and more specifically to the removal and etching of polycrystalline materials such as metals. [Cross-reference to joint applications]

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 257,214 (filed October 19, 2021), entitled "RUTHENIUM CMP CHEMISTRY BASED ON HALOGENATION"; and to U.S. Patent Application No. 17 / 674,593 (filed February 17, 2022), entitled "RUTHENIUM CMP CHEMISTRY BASED ON HALOGENATION"; and to U.S. Patent Application No. 17 / 674,579 (filed February 17, 2022), entitled "METHOD FOR WET ATOMIC LAYER ETCHING OF RUTHENIUM"; the disclosures of these applications are incorporated herein by reference. Prior Technology

[0003] This disclosure relates to the fabrication of semiconductor devices, and more specifically to the removal and etching of polycrystalline materials such as metals. During conventional semiconductor manufacturing, various metals formed on a substrate can be removed using patterned etching, chemical mechanical polishing (CMP), and other techniques. Several techniques for etching layers on a substrate are known, including plasma- or vapor-phase etching (also known as dry etching) and liquid-based etching (also known as wet etching).

[0004] Chemical mechanical polishing (CMP) has become an indispensable tool for planarization in semiconductor manufacturing. CMP uses a slurry containing solvents, abrasives, and reactive chemicals designed to etch the surface being polished. The combination of surface reaction and abrasive action results in the removal of reinforcing material at high points on the surface, thereby achieving surface planarization.

[0005] One challenge of chemical mechanical polishing (CMP) is surface etching. Surface etching must be well controlled to prevent pitting, buildup of etching products on the substrate surface, and surface damage due to the mechanical removal of insoluble products. However, surface etching control must never come at the expense of throughput. That is, the etching rate must be high enough to support material removal rates compatible with mass production.

[0006] Ruthenium (Ru) is a precious metal currently considered as a copper alternative in back-end edge processing (BEOL) metallization and front-end edge processing (FEOL) features such as embedded power rails (power rails located below active devices). However, Ruthenium's noble properties make it difficult to etch and planarize.

[0007] For example, U.S. Patent Application No. 17 / 580,936 (filed January 21, 2022), under common examination, entitled "Dynamically Adjusted Purge Timing in Wet Atomic Layer Etching," describes a wet ALE process for etching various transition metals, including ruthenium. In this application under common examination, a modified surface layer is formed by exposing the surface of Ru metal to an oxidizing agent, which forms a metal oxide on the exposed surface. While ruthenium dioxide (RuO2) surface layers are readily formed using chemical solutions containing dissolved oxygen or other oxidizing agents, the stability and insolubility of this surface oxide make it difficult to handle during etching. Therefore, strong oxidizing agents are commonly used in conventional etching processes to generate soluble or volatile ruthenium oxide compounds.

[0008] Several commercially available ruthenium etchants contain strong oxidizing agents, such as sodium hypochlorite, cerium ammonium nitrate, and periodic acid, which oxidize the ruthenium surface to produce ruthenium tetroxide (RuO4). Of these chemicals, the most effective etchants, cerium ammonium nitrate and sodium hypochlorite, are problematic because they cause metal contamination hazards in the subsequently formed apparatus. For example, the addition of trace amounts of sodium or cerium in the front-end process can significantly degrade transistor performance. On the other hand, periodic acid is expensive and cannot be used to provide a cost-effective ruthenium etching process.

[0009] Another problem with conventional etching processes used to etch ruthenium is that they tend to produce a rough post-etched surface. This is because ruthenium grain boundaries tend to be more reactive than the grain surface, leading to preferential etching at the grain boundaries compared to the grain surface. Therefore, chemical mechanical polishing is often used in conventional processes to smooth the post-etched ruthenium surface.

[0010] Similar to ruthenium etching chemicals, conventional ruthenium CMP slurries typically rely on strong oxidants to etch the ruthenium surface. As with etching, these oxidants tend to react preferentially at grain boundaries, leading to pitting on the Ru surface during CMP. Although less aggressive oxidants can be used to reduce pitting, their use in CMP slurries results in significantly lower material removal rates. Since the corrosion products are no longer soluble, the material removal rate is significantly reduced, making mechanical polishing the only remaining treatment for material removal.

[0011] Therefore, there is a need for new ruthenium CMP slurry chemicals that improve the smoothness of the etched surface while providing high material removal rates. Summary of the Invention

[0012] This disclosure provides novel corrosion control chemicals for ruthenium (Ru) chemical mechanical polishing (CMP) treatments. More specifically, this disclosure provides novel ruthenium CMP slurry chemicals that utilize halogenation of the ruthenium surface to form ruthenium halide or ruthenium halide oxide surface intermediates, and reactive dissolution to chemically remove the ruthenium halide or ruthenium halide oxide surface intermediates. Halogenation of the ruthenium surface can be achieved using radical halogenation of a chemical halogenating agent. Halogenation is self-limiting in itself, and the kinetics of reactive dissolution are temperature-dependent. The self-limiting nature of halogenation limits pitting corrosion on the ruthenium surface. The temperature-dependent dissolution kinetics further contribute to the planarization of the ruthenium surface, as the mechanical polishing treatment increases the local temperature around high points on the surface.

[0013] According to one embodiment, this document provides an improved chemical mechanical polishing (CMP) process for planarizing ruthenium surfaces. In the CMP process disclosed herein, the ruthenium surface (e.g., an etched ruthenium surface) is exposed to a CMP slurry containing a halogenating agent that reacts with the ruthenium surface to produce a ruthenium halide or ruthenium halide oxide surface, and ligands for ligand-assisted reactions to dissolve the ruthenium halide or ruthenium halide oxide surface. The relative amounts of halogenating agent and ligands in the CMP slurry can be controlled to provide a diffusion-limited etching process with improved post-etched surface morphology, while also providing high material removal rates.

[0014] Various halogenating agents (e.g., trichloroisocyanuric acid (TCCA)) in non-aqueous solvents (e.g., ethyl acetate (EA)) can be used for this treatment. Since ruthenium halide or ruthenium halide oxide surfaces are insoluble in non-aqueous solvents, ligand-assisted reactive dissolution is used to facilitate the chemical removal of ruthenium halide or ruthenium halide oxide surfaces. Various ligands (e.g., acetone (ACAC) or aminopolycarboxylic acids) can be used for reactive dissolution of ruthenium halide or ruthenium halide oxide surfaces.

[0015] According to another embodiment, this document provides a composition comprising a novel CMP slurry. The novel CMP slurry typically includes a solvent, a halogenating agent for halogenating a ruthenium surface to form a ruthenium halide surface, a ligand that reacts with the ruthenium halide surface to dissolve the ruthenium halide surface, and a catalyst that increases the rate of ligand exchange reaction with the ruthenium halide surface. In several embodiments, the relative amounts of the halogenating agent and ligand in the CMP slurry may be selected to provide a halogenation rate of the ruthenium surface greater than the dissolution rate of the ruthenium halide surface.

[0016] In several embodiments, the CMP slurry described herein includes a halogenating agent but not an oxidizing agent that forms an oxide. As used herein, an oxidizing agent that forms an oxide is one that reacts with the ruthenium surface to form a ruthenium oxide layer on the ruthenium surface. While a halogenating agent can halogenate and chemically oxidize the ruthenium surface, it does not react with the ruthenium surface to form a ruthenium oxide layer on the ruthenium surface.

[0017] In other embodiments, the CMP slurry described herein may include a halogenating agent and an oxidizing agent that forms oxides. For example, the CMP slurry may further contain a predetermined amount of water or dissolved oxygen. When halogenation is performed in the presence of an oxidizing agent that forms oxides (such as water or dissolved oxygen), a ruthenium halide surface comprising ruthenium-oxide-halogen substances is generated on the ruthenium surface. Since ruthenium-oxide-halogen substances are generally more soluble than the ruthenium halide surface layer, the presence of ruthenium-oxide-halogen substances increases the material removal rate during CMP processing.

[0018] In several embodiments, the halogenating agent included in the CMP slurry may be a chlorinating agent. In such embodiments, the chlorinating agent may react with a ruthenium surface to form a ruthenium chloride surface, and a ligand may react with the ruthenium chloride surface.

[0019] In several embodiments, the halogenating agent may include a chlorinating agent dissolved in a solvent. For example, the chlorinating agent may be trichloroisocyanuric acid (TCCA), oxalic acid, thionyl chloride, or N-chlorosuccinimide, and the solvent may be ethyl acetate, acetone, acetonitrile, or a chlorinated hydrocarbon. In such embodiments, the halogenating agent may react with the ruthenium surface to form a self-limiting RuCl3 passivation layer.

[0020] It should be noted that the halogenating agents disclosed herein are not strictly limited to chlorinating agents. In several embodiments, for example, the halogenating agent may be a fluorinating agent. In such embodiments, the fluorinating agent may react with the ruthenium surface to form a ruthenium fluoride surface, and the ligand may also react with the ruthenium fluoride surface. In other embodiments, the halogenating agent may be a brominating agent. In such embodiments, the brominating agent may react with the ruthenium surface to form a ruthenium bromide surface, and the ligand may also react with the ruthenium bromide surface.

[0021] In several embodiments, the ligands included in the CMP slurry may include ethylenediaminetetraacetic acid (EDTA), acetoacetone (ACAC), iminodiacetic acid (IDA), or diethylenetriaminepentaacetic acid (DTPA), and the catalyst may be a base. Examples of bases that may be included in the CMP slurry to increase the rate of ligand exchange reaction with the ruthenium halide surface include (but are not limited to) potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), or tetramethylammonium hydroxide ((CH3)4NOH).

[0022] In several embodiments, the CMP slurry may be non-aqueous and may contain abrasive particles. In one embodiment, the CMP slurry disclosed herein may use EA as a solvent and may further contain nano-abrasive particles (e.g., silicon dioxide (SiO2)), a halogenating agent (e.g., TCCA), a ligand (e.g., aminopolycarboxylic acid), and an alkali that catalyzes the ligand-assisted reaction dissolution.

[0023] Accordingly, the techniques disclosed herein provide a ruthenium CMP treatment and a ruthenium CMP slurry that primarily utilize halogenation to generate ruthenium-halogen compounds on the ruthenium surface, and employ ligand-assisted reaction dissolution to chemically remove the ruthenium-halogen compounds. Because different ligands react at different rates with the halogenated surface, a variety of different ligands can be used to tune the chemical etching rate achieved during a given CMP treatment. One advantage of the CMP treatment and CMP slurry disclosed herein is that the mechanical properties of the ruthenium-halogen compounds are more suitable for CMP treatment. Therefore, the CMP treatment and CMP slurry described herein improve the smoothness of the ruthenium surface after etching while providing a high material removal rate.

[0024] As further described herein, this disclosure provides numerous embodiments of methods for planarizing ruthenium surfaces using the novel CMP chemicals disclosed herein. Of course, for clarity, the order in which the different steps described herein are discussed is presented. Generally, these steps can be performed in any suitable order. Furthermore, although various features, techniques, configurations, etc., may be discussed in different places within this disclosure, it is intended that each concept can be implemented independently of or in combination with each other. Therefore, the invention can be implemented and viewed in many different ways.

[0025] According to one embodiment, this document provides a method for removing ruthenium. The method typically begins by positioning a substrate in a chemical mechanical polishing (CMP) system, wherein the CMP system includes an abrasive pad mounted on a rotatable plate such that the abrasive pad can be rotated and moved across a surface of the substrate, the substrate including a ruthenium surface. The method then includes dispensing a slurry onto the abrasive pad. The slurry typically includes a solvent, a halogenating agent that halogenates the ruthenium surface to form a ruthenium halide surface, a ligand that reacts with the ruthenium halide surface to dissolve the ruthenium halide surface, and a catalyst that increases the rate of the ligand exchange reaction with the ruthenium halide surface. The method then includes grinding the ruthenium surface using the slurry until a predetermined amount of ruthenium has been removed.

[0026] In several embodiments, the method may further include controlling the relative amounts of the halogenating agent and the ligand in the slurry such that the halogenation rate of the ruthenium surface is greater than the dissolution rate of the ruthenium halide surface.

[0027] In several embodiments, dispensing a slurry on the polishing pad may include dispensing a slurry that does not contain an oxidizing agent that forms an oxide; in other embodiments, dispensing a slurry that contains both the halogenating agent and an oxidizing agent that forms an oxide may be included on the polishing pad.

[0028] In several embodiments, the halogenating agent comprises a chlorinating agent that reacts with the ruthenium surface to form a ruthenium chloride surface. In such embodiments, the ligand may react with the ruthenium chloride surface to dissolve it. In several embodiments, the catalyst that enhances the ion exchange reaction with the ruthenium chloride surface may be a base.

[0029] It should be noted that this summary does not specify every embodiment and / or incremental novel aspects of the invention or the claims. Rather, it provides only a preliminary discussion of different embodiments and points of novelty relative to the prior art. Further details and / or possible perspectives regarding the invention and its embodiments will be provided in the following further discussion of the embodiments of the invention and the corresponding drawings. Simple Explanation of the Diagram

[0030] A more complete understanding of the invention and its advantages can be obtained by referring to the following description in conjunction with the accompanying drawings, in which similar symbols represent similar features. However, it should be noted that the drawings only show exemplary embodiments of the disclosed concepts and should not be considered as limiting the scope, as other equally effective embodiments are permissible based on the disclosed concepts.

[0031] Figure 1 is a block diagram of a chemical mechanical grinding (CMP) system.

[0032] Figure 2 is a flowchart illustrating one embodiment of a method using the techniques described herein. Implementation

[0033] Etching ruthenium with liquid (wet) chemicals typically uses strong oxidizing agents to produce soluble ruthenium. Currently available Ru etchants use cerium ammonium nitrate, periodic acid, and hypochlorite ions to oxidize metallic RuO to Ru8+ as RuO4 or related hydrated substances. However, these oxidations leave a rough post-etched surface due to the increased reactivity of ruthenium at grain boundaries. Another known drawback of conventional wet ruthenium etching is the high solubility of the reaction products. This solubility leads to oxidation-limited etching, which only exacerbates the roughness formed during etching. These drawbacks are amplified when these same oxidizing agents are used as part of the Ru CMP slurry. Therefore, new etching chemicals for Ru CMP are needed to better remove ruthenium.

[0034] This disclosure provides novel CMP slurry chemicals for planarizing ruthenium (Ru) surfaces. As described in more detail below, the Ru CMP slurry described herein includes a halogenating agent for chemically modifying the ruthenium surface and forming a ruthenium halide or ruthenium halide oxide passivation layer on the ruthenium surface, ligands (or multiple ligands) for reacting and dissolving the ruthenium halide or ruthenium halide oxide passivation layer, a strong base, or other catalyst to increase the rate of ligand reaction, and a grinding media in a non-aqueous solvent. Surfactants or other stabilizers may also be used to help all these components remain dissolved or suspended in the CMP slurry.

[0035] Unlike conventional CMP slurry chemicals used for planarizing ruthenium, the CMP slurry chemicals disclosed herein focus on oxidizing Ru0 to Ru3+ rather than the higher oxidation state achieved by conventional Ru CMP slurries. Using a lower oxidation state has the advantage of providing a choice between producing both soluble and insoluble ruthenium products. The CMP slurry chemicals disclosed herein achieve the lower oxidation state by primarily using halogenation rather than oxide on the ruthenium surface to form a ruthenium halide or ruthenium halide passivation layer. Direct halogenation of metallic Ru0 results in the formation of Ru3+X3 (where X is a halogen). In several embodiments, halogenation can be achieved by exposing the ruthenium surface to a CMP slurry containing a chlorinating agent, a fluorinating agent, or a brominating agent.

[0036] Chlorination of ruthenium surfaces can be achieved using a variety of chlorinating agents, such as trichloroisocyanuric acid (TCCA), oxalic acid, thionyl chloride, and N-chlorosuccinimide. Exposing the ruthenium surface to these chlorinating agents chemically modifies it to form a ruthenium chloride passivation layer, for example, but not limited to, ruthenium trichloride (RuCl3). It should be noted that this is not an exhaustive list of all possible chlorinating agents that can be used to form a ruthenium chloride passivation layer. Furthermore, it should be noted that ruthenium surfaces can be exposed to other halogenating agents to form other ruthenium halide or ruthenium halide passivation layers. For example, fluorination or bromination of ruthenium surfaces can be achieved using fluorinating or brominating agents, such as 1-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate, N-fluorobenzenesulfonimide, N-bromosuccinimide, or dibromoisocyanuric acid. Upon exposure to these halogenating agents, a ruthenium fluoride or ruthenium bromide passivation layer is formed on the ruthenium surface. Halogenating agents are typically hydrolyzed by water. Therefore, regardless of the halogenating agent used, halogenation must be carried out in a solvent or solvent mixture that does not undergo hydrolysis.

[0037] In one exemplary embodiment, the CMP slurry according to this disclosure may include TCCA dissolved in a non-aqueous solvent such as ethyl acetate (EA), acetone, acetonitrile, or chlorinated hydrocarbons. When exposed to TCCA in a non-aqueous solvent (e.g., ethyl acetate), RuO rapidly reacts to form a self-limiting ruthenium chloride (RuCl3) passivation layer. If an oxidizing agent (e.g., water or dissolved oxygen) that forms oxides is present during the chlorination reaction, the self-limiting ruthenium chloride passivation layer may also contain RuOxCly material. "Self-limiting" means that only a finite thickness of the ruthenium surface is modified or removed regardless of how long the given etching solution is in contact with the ruthenium surface. The self-limiting reaction may be limited by one or more monolayer reactions or partial monolayer reactions. Once formed, the ruthenium chloride passivation layer may dissolve through a ligand exchange reaction. Adding reactive ligands to a non-aqueous TCCA solution transforms the CMP slurry chemistry described herein from self-limiting surface passivation to a continuous etching process.

[0038] A variety of ligands can be used in CMP slurries to chemically remove ruthenium chloride passivation layers through ligand-assisted reaction dissolution. For example, ligands such as acetoacetone (ACAC) or aminopolycarboxylic acids are effective for the ligand-assisted dissolution of insoluble RuCl3. Ethylenediaminetetraacetic acid (EDTA) is an example of an aminopolycarboxylic acid, which reacts with RuCl3 to form ruthenium aminopolycarboxylic acid. Alternative ligands for the reaction dissolution of insoluble RuCl3 include (but are not limited to) imine diacetic acid (IDA) and diethylenetriaminepentaacetic acid (DTPA). EDTA, IDA, and DTPA can be used in aqueous solutions, while ACAC can be used in aqueous solutions, ethanol, dimethyl sulfoxide (DSMO), or other organic solvents. In several embodiments, one or more ligands included in the CMP slurry can be used to modulate the chemical etching rate achieved during a given CMP treatment. For example, different ligands react with ruthenium chloride passivation layers (or other ruthenium halide surface layers) at different rates. Because the kinetics of the reaction are highly dependent on the reactivity of the ligands used, different ligands can be selected and used to modulate the chemical etching rate achieved during a given CMP process.

[0039] Ligand exchange reactions (e.g., replacing Cl ligands with EDTA) are base-catalyzed. Therefore, a base is required in CMP slurries to deprotonate EDTA (or ACAC) to form ligands in reactive anionic forms. Various bases, such as potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), tetramethylammonium hydroxide ((CH3)4NOH), and other strong bases, can be used in CMP slurries to deprotonate the ligands. Non-aqueous bases (e.g., quaternary ammonium hydroxide, trialkylamines) or basic solvents (e.g., amino alcohols) can also be used.

[0040] Therefore, in one embodiment, the CMP slurry described herein may contain TCCA to promote the chlorination reaction with the ruthenium surface and form a ruthenium chloride (e.g., RuCl3) passivation layer on the ruthenium surface, ligands such as ACAC or EDTA for ligand-assisted dissolution of the ruthenium chloride passivation layer, and bases or other catalysts to increase the ligand reaction rate and continuously etch the ruthenium surface. The relative kinetic rates of the chlorination reaction and the ligand-assisted dissolution reaction can be adjusted by changing the concentrations of TCCA and ligands in the slurry solution.

[0041] As previously mentioned, conventional ruthenium wet etching chemicals and CMP slurries rely on oxidation-limited etching, which increases surface roughness during etching and planarization. In contrast, the technique described herein improves the post-etched surface morphology by ensuring the entire etching reaction is dissolution-limited (i.e., by ensuring the halogenation rate is much faster than the ligand-assisted dissolution rate). This can be achieved using the technique described herein because the halogenation kinetics and dissolution kinetics can be independently controlled by adjusting the relative amounts of halogenating agents and ligands contained in the CMP slurry, such that the halogenation rate on the ruthenium surface is greater than the dissolution rate on the ruthenium halide surface. Existing oxidant-based etching chemistry lacks this independent control.

[0042] In several embodiments, the CMP slurry described herein contains a halogenating agent but not an oxidizing agent that forms oxides, such as water or dissolved oxygen. In other embodiments, the CMP slurry may contain both a halogenating agent and an oxidizing agent that forms oxides. In one exemplary embodiment, the CMP slurry may further include a predetermined amount of water or dissolved oxygen. When chlorination is performed in the presence of an oxidizing agent that forms oxides (such as water or dissolved oxygen), a ruthenium chloride (e.g., RuCl3) passivation layer containing RuOxCly is formed on the ruthenium surface. Since RuOxCly is generally more soluble than the ruthenium chloride passivation layer, the presence of RuOxCly on the ruthenium surface increases the material removal rate achieved in the CMP process.

[0043] In addition to the aforementioned liquid components, the CMP slurry described herein may further contain abrasive media, such as silicon dioxide, alumina, cerium dioxide, or other nanoparticles, to mechanically abrade the ruthenium surface. This mechanical abrasion increases the local temperature at high points on the wafer surface. This localized heating is used to increase etching kinetics, which helps to planarize the wafer. Since the ligand exchange reaction used to dissolve RuCl3 is very temperature-sensitive, the localized heating generated at high points is very effective in increasing the local etching rate in these regions.

[0044] In addition to the novel CMP slurry, this disclosure provides an improved CMP process that utilizes the CMP slurry chemicals disclosed herein to planarize ruthenium surfaces. The CMP process disclosed herein can be used with a variety of CMP tools and systems. Figure 1 illustrates an example of a CMP system 100, which includes a polishing pad 105 mounted on top of a rotating plate 110 and a slurry dispenser 115 for distributing slurry 120 over the top of the polishing pad 105. As the plate 110 rotates, the movement of the plate 110 distributes the slurry 120 onto the surface of the polishing pad 105. A wafer carrier 125 holds and positions a wafer 130 (e.g., a semiconductor substrate) and applies a downward force between the wafer surface and the polishing pad 105. The wafer carrier 125 is rotatable and radially movable along the plate 110. A pad adjuster 135 is used to maintain pad flatness and surface quality. The techniques described herein include improved slurry chemistry as part of the chemical reaction portion of chemical mechanical material removal. As previously described, Figure 1 illustrates an example CMP system. Those skilled in the art will recognize that the techniques, methods, processes, and slurry chemicals described herein can be used with a variety of CMP tools and systems, and are not limited to those shown in Figure 1.

[0045] Finally, this disclosure provides various methods for utilizing the novel CMP slurry chemicals and CMP treatments disclosed herein. Figure 2 illustrates one embodiment of a method that utilizes the techniques described herein to planarize or remove ruthenium from a substrate surface. It will be appreciated that the embodiment in Figure 2 is merely illustrative, and additional methods may utilize the techniques described herein. Furthermore, additional processing steps may be added to the method shown in Figure 2, as the described steps are not intended to be exclusive. Moreover, the order of the steps is not limited to the order shown in the figures, as different orders may occur and / or multiple steps may be combined or performed simultaneously.

[0046] Figure 2 illustrates one embodiment of a method 200 for removing ruthenium. Method 200 typically begins by positioning a substrate in a chemical mechanical polishing (CMP) system (in step 210). Figure 1 illustrates one embodiment of a CMP system (or CMP tool) in which the substrate may be positioned in step 210. As described above and as shown in Figure 1, the CMP system 100 typically includes an abrasive pad 105 mounted on a rotatable plate 110, such that the abrasive pad 105 can rotate and move across the surface of the substrate. In several embodiments, the substrate may include a ruthenium surface.

[0047] Next, method 200 may include dispensing a slurry onto a polishing pad (in step 220). As described above, the slurry typically includes a solvent, a halogenating agent for halogenating the ruthenium surface to form a ruthenium halide surface, a ligand that reacts with the ruthenium halide surface to dissolve the ruthenium halide surface, and a catalyst that increases the rate of ligand exchange reaction with the ruthenium halide surface. In several embodiments, method 200 may include controlling the relative amounts of the halogenating agent and ligands contained in the slurry such that the halogenation rate of the ruthenium surface is greater than the dissolution rate of the ruthenium halide surface.

[0048] Next, method 200 may include grinding the ruthenium surface with a slurry until a predetermined amount of ruthenium has been removed (in step 230).

[0049] It should be noted that the terms "an embodiment" or "an embodiment" throughout this specification indicate that a particular feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention, but does not imply that they exist in every embodiment. Therefore, the phrases "in an embodiment" or "in an embodiment" appearing throughout this specification do not necessarily refer to the same embodiment of the invention. Furthermore, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. In other embodiments, numerous additional layers and / or structures may be included, and / or the described features may be omitted.

[0050] As used herein, the term "substrate" refers to and includes the base material or structure on which materials are formed. It will be understood that a substrate may include a single material, multiple layers of different materials, one or more layers having different materials or structural regions, etc. These materials may include semiconductors, insulators, conductors, or combinations thereof. For example, a substrate may be a semiconductor substrate, a base semiconductor layer on a support structure, or a metal electrode or semiconductor substrate having one or more layers, structures, or regions formed thereon. A substrate may be a conventional silicon substrate or other host substrate including layers of semiconductor material. As used herein, the term "host substrate" represents and includes not only silicon wafers but also silicon-on-insulator (SOI) substrates (e.g., silicon-on-sapphire (SOS) substrates and silicon-on-glass (SOG) substrates), silicon epitaxial layers on a base semiconductor substrate, and other semiconductor or optoelectronic materials such as silicon germanium, germanium, gallium arsenide, gallium nitride, and indium phosphide. Substrates may be doped or undoped.

[0051] Systems and methods for planarizing substrate surfaces are described in numerous embodiments. The substrate may include any material portion or structure of a device, particularly a semiconductor or other electronic device, and may be, for example, a base substrate structure, such as a semiconductor substrate or a layer, such as a thin film, on or over a base substrate structure. Therefore, the substrate is not intended to be limited to any particular base structure, underlying layer, or overlying layer, whether patterned or unpatterned, but is contemplated to include any such layer or base structure, and any combination of layers and / or base structures.

[0052] Those skilled in the art will understand that the various embodiments described can be practiced without one or more specific details, or with other alternatives and / or additional methods, materials, or components. In other instances, conventional structures, materials, or operations have not been shown or described in detail to avoid obscuring the various embodiments of the invention. Similarly, for illustrative purposes, specific quantities, materials, and configurations are set forth to provide a thorough understanding of the invention. However, the invention can be practiced without these specific details. Furthermore, it should be understood that the various embodiments shown in the drawings are presented illustratively and are not necessarily drawn to scale.

[0053] In view of this implementation, further modifications and alternative embodiments of the system and method will be readily apparent to those skilled in the art. Therefore, it will be understood that the system and method are not limited to these exemplary configurations. It should be understood that the system and method forms shown and described herein are to be considered exemplary embodiments. Various changes may be made in the embodiments. Therefore, although ruthenium CMP technology is described herein with reference to specific embodiments, various modifications and changes may be made without departing from the scope of this disclosure. Thus, the specification and drawings are to be considered illustrative rather than restrictive, and such modifications are intended to be included within the scope of this disclosure. Furthermore, any benefits, advantages, or solutions to problems described herein with respect to specific embodiments are not intended to be construed as key, necessary, or essential features or elements of any or all claims.

[0054] Those skilled in the art will understand that many variations can be made to the operation of the aforementioned technology while still achieving the same purpose of this disclosure. The scope of this disclosure is intended to encompass such variations. Therefore, the above description of embodiments of the present invention is not intended to be limiting. Any limitations on embodiments of the present invention are described in the following claims.

[0055] 100: CMP System 105: Grinding Pad 110: Tablet 115: Slurry Distributor 120: Slurry 125: Wafer carrier 130: Wafer 135: Pad Adjuster 200: Method 210-230: Steps

Claims

1. A CMP composition comprising: a chemical mechanical polishing (CMP) slurry, comprising: A non-aqueous solvent; A halogenating agent that halogenates a ruthenium surface to form a ruthenium halide surface that is insoluble in the non-aqueous solvent; A ligand that reacts with the ruthenium halide surface to dissolve the ruthenium halide surface; and a catalyst that increases the rate of the ligand exchange reaction with the ruthenium halide surface; wherein the CMP slurry does not contain an oxidant that forms oxides.

2. The CMP composition of claim 1, wherein the CMP slurry is non-aqueous, and wherein the non-aqueous CMP slurry prevents the hydrolysis of the halogenating agent.

3. The CMP composition as claimed in claim 1, wherein the CMP slurry comprises abrasive particles.

4. The CMP composition of claim 1, wherein the relative amounts of the halogenating agent and the ligand in the CMP slurry provide a halogenation rate for the ruthenium surface that is greater than the dissolution rate of the ruthenium halide surface.

5. The CMP composition of claim 1, wherein by including the halogenating agent in the CMP slurry and not including the oxidizing agent that forms oxides, the CMP slurry restricts the oxidation state of the ruthenium surface to Ru3+.

6. The CMP composition of claim 1, wherein the CMP slurry does not contain water, dissolved oxygen or other oxidizing agents that form oxides.

7. The CMP composition of claim 1, wherein the halogenating agent reacts with the ruthenium surface to form a self-limiting ruthenium trichloride (RuCl3) passivation layer.

8. The CMP composition of claim 1, wherein the halogenating agent comprises trichloroisocyanuric acid (TCCA), oxalic acid, thionyl chloride, or N-chlorosuccinimide.

9. The CMP composition of claim 1, wherein the non-aqueous solvent is ethyl acetate, acetone, acetonitrile, or a chlorinated hydrocarbon.

10. The CMP composition of claim 1, wherein the halogenating agent is a chlorinating agent, wherein the chlorinating agent reacts with the ruthenium surface to form a ruthenium chloride surface, and wherein the ligand is reactive with the ruthenium chloride surface.

11. The CMP composition of claim 1, wherein the halogenating agent is a fluorinating agent, wherein the fluorinating agent reacts with the ruthenium surface to form a ruthenium fluoride surface, and wherein the ligand is reactive with the ruthenium fluoride surface.

12. The CMP composition of claim 1, wherein the halogenating agent is a brominating agent, wherein the brominating agent reacts with the ruthenium surface to form a ruthenium bromide surface, and wherein the ligand is reactive with the ruthenium bromide surface.

13. The CMP composition of claim 1, wherein the ligand comprises ethylenediaminetetraacetic acid (EDTA), acetoacetone (ACAC), iminodiacetic acid (IDA), or diethylenetriaminepentaacetic acid (DTPA).

14. The CMP composition of claim 1, wherein the catalyst is a base.

15. The CMP composition of claim 14, wherein the base comprises potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), or tetramethylammonium hydroxide ((CH3)4NOH).

16. The CMP composition of claim 1, wherein the ligand reacts with the ruthenium halide surface to dissolve the ruthenium halide surface via the ligand exchange reaction, and provides ligand-assisted dissolution of the ruthenium halide surface.

17. The CMP composition of claim 1, wherein the halogenating agent in the non-aqueous solvent reacts with the ruthenium surface to form a self-confined ruthenium halide passivation layer, and wherein the ligand causes the CMP process using the CMP slurry to change from self-confined surface passivation to continuous etching.

18. The CMP composition of claim 17, wherein the catalyst is a base, wherein the base deprotonates the ligand to increase the rate of the ligand exchange reaction with the ruthenium halide surface and continuously etches the ruthenium surface.

19. A method for removing ruthenium, the method comprising: positioning a substrate in a chemical mechanical polishing (CMP) system, the CMP system including an abrasive pad mounted on a rotatable plate such that the abrasive pad can be rotated and moved across a surface of the substrate, the substrate including a ruthenium surface; dispensing a slurry on the abrasive pad, the slurry comprising: a non-aqueous solvent; a halogenating agent that halogenates the ruthenium surface to form a ruthenium halide surface insoluble in the non-aqueous solvent; a ligand that reacts with the ruthenium halide surface to dissolve the ruthenium halide surface; and a catalyst that increases the rate of a ligand exchange reaction with the ruthenium halide surface, wherein the slurry does not contain an oxidizing agent that forms an oxide; and abrading the ruthenium surface using the slurry until a portion of the ruthenium has been removed.

20. The method for removing ruthenium as claimed in claim 19 further comprises controlling the relative amounts of the halogenating agent and the ligand in the slurry such that the halogenation rate of the ruthenium surface is greater than the dissolution rate of the ruthenium halide surface.

21. The method for removing ruthenium as claimed in claim 20, wherein the halogenating agent comprises a chlorinating agent that reacts with the ruthenium surface to form a ruthenium chloride surface, and wherein the ligand reacts with the ruthenium chloride surface to dissolve the ruthenium chloride surface.

22. The method for removing ruthenium as claimed in claim 19, wherein the halogenating agent comprises a chlorinating agent that reacts with the ruthenium surface to form a ruthenium chloride surface, and wherein the ligand reacts with the ruthenium chloride surface to dissolve the ruthenium chloride surface.

23. The method for removing ruthenium as claimed in claim 19, wherein the catalyst is a base.

24. The method for removing ruthenium as claimed in claim 23, wherein the base comprises potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), or tetramethylammonium hydroxide ((CH3)4NOH).

25. The method for removing ruthenium as claimed in claim 19, wherein the slurry is non-aqueous and wherein the non-aqueous slurry prevents the hydrolysis of the halogenating agent.

26. The method for removing ruthenium as claimed in claim 19, wherein the slurry comprises abrasive particles.

27. The method for removing ruthenium as claimed in claim 19, wherein by including the halogenating agent in the slurry and not including the oxidizing agent that forms oxides, the slurry restricts the oxidation state of the ruthenium surface to Ru3+.

28. The method for removing ruthenium as claimed in claim 19, wherein the slurry does not contain water, dissolved oxygen or other oxidizing agents that form oxides.

29. The method for removing ruthenium as claimed in claim 19, wherein the halogenating agent reacts with the ruthenium surface to form a self-limiting ruthenium trichloride (RuCl3) passivation layer.

30. The method for removing ruthenium as claimed in claim 19, wherein the halogenating agent comprises trichloroisocyanuric acid (TCCA), oxalic acid, thionyl chloride, or N-chlorosuccinimide.

31. The method for removing ruthenium as claimed in claim 19, wherein the non-aqueous solvent is ethyl acetate, acetone, acetonitrile, or a chlorinated hydrocarbon.

32. The method for removing ruthenium as claimed in claim 19, wherein the halogenating agent is a fluorinating agent, wherein the fluorinating agent reacts with the ruthenium surface to form a ruthenium fluoride surface, and wherein the ligand is reactive with the ruthenium fluoride surface.

33. The method for removing ruthenium as claimed in claim 19, wherein the halogenating agent is a brominating agent, wherein the brominating agent reacts with the ruthenium surface to form a ruthenium bromide surface, and wherein the ligand is reactive with the ruthenium bromide surface.

34. The method for removing ruthenium as claimed in claim 19, wherein the ligand comprises ethylenediaminetetraacetic acid (EDTA), acetoacetone (ACAC), iminodiacetic acid (IDA), or diethylenetriaminepentaacetic acid (DTPA).

35. The method for removing ruthenium as claimed in claim 19, wherein the ligand reacts with the ruthenium halide surface to dissolve the ruthenium halide surface through the ligand exchange reaction, and provides ligand-assisted dissolution of the ruthenium halide surface.

36. The method for removing ruthenium as claimed in claim 35 further comprises controlling the relative amounts of the halogenating agent and the ligand in the slurry such that the halogenation rate of the ruthenium surface is greater than the dissolution rate of the ruthenium halide surface.

37. The method for removing ruthenium as claimed in claim 36, wherein the halogenating agent comprises a chlorinating agent that reacts with the ruthenium surface to form a ruthenium chloride surface, and wherein the ligand reacts with the ruthenium chloride surface to dissolve the ruthenium chloride surface.

38. The method for removing ruthenium as claimed in claim 19, wherein the halogenating agent in the non-aqueous solvent reacts with the ruthenium surface to form a self-confined ruthenium halide passivation layer, and wherein the ligand causes the method for removing ruthenium to change from self-confined surface passivation to continuous etching.

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