Halide-Based Ruthenium CMP Chemistry

Abstract

The present disclosure provides novel corrosion control chemistries for use in ruthenium (Ru) chemical mechanical polishing (CMP) processes. More specifically, the present disclosure provides improved CMP slurry chemistries and CMP processes for planarizing ruthenium surfaces. In the CMP process disclosed herein, a ruthenium surface (e.g., a post-etch ruthenium surface) is exposed to a CMP slurry containing a halogenating agent that reacts with the ruthenium surface to form a ruthenium halide surface and a ligand for ligand-assisted reactive dissolution of the ruthenium halide surface. The relative amounts of the halogenating agent and ligand in the CMP slurry can be controlled to provide a diffusion-limited etch process that improves post-etch surface morphology while providing high material removal rates.

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 257,214, entitled "RUTHENIUM CMP CHEMISTRY BASED ON HALOGENATION", filed October 19, 2021, which claims priority to U.S. Provisional Patent Application No. 17 / 674,593, entitled "RUTHENIUM CMP CHEMISTRY BASED ON HALOGENATION", filed February 17, 2022, and which claims priority to U.S. Provisional Patent Application No. 17 / 674,579, entitled "METHOD FOR WET ATOMIC LAYER ETCHING OF RUTHENIUM", filed February 17, 2022, the disclosures of which are expressly incorporated herein by reference. [Background technology]

[0002] This disclosure relates to the manufacture of semiconductor devices, and in particular to the removal and etching of polycrystalline materials such as metals. During typical semiconductor fabrication, various metals formed on a substrate may be removed by patterned etching, chemical mechanical polishing (CMP), and other techniques. Various techniques are known for etching layers on a substrate, including plasma-based or gas-phase etching (called dry etching) and liquid-based etching (called wet etching).

[0003] 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 attack the surface being polished. The combination of the surface reaction and the action of the abrasives enhances material removal at high levels on the surface, thus planarizing the surface.

[0004] One of the challenges with chemical mechanical polishing is surface erosion. Surface erosion must be well controlled to prevent surface damage due to pitting, accumulation of erosion products on the substrate surface, and mechanical removal of insoluble products. However, surface erosion control should not come at the expense of throughput; that is, erosion rates must be high to support material removal rates compatible with high volume manufacturing.

[0005] Ruthenium (Ru) is a precious metal currently being considered as a replacement for copper in back-end-of-line (BEOL) metallization, as well as for front-end-of-line (FEOL) features such as buried power rails (power rails located below active devices). However, the precious metal nature of ruthenium makes it difficult to etch and planarize.

[0006] For example, co-pending U.S. patent application Ser. No. 17 / 580,936, filed Jan. 21, 2022, entitled “Dynamically Adjusted Purge Timing in Wet Atomic Layer Etching,” describes a wet ALE process for etching various transition metals, including ruthenium. In the co-pending application, a modified surface layer is formed by exposing a Ru metal surface to an oxidizing agent, which forms a metal oxide on the exposed surface. Ruthenium dioxide (RuO) is etched using a chemical solution containing dissolved oxygen or another oxidizing agent. 2 Although it is easy to form a ruthenium oxide surface layer, the stability and insolubility of this surface oxide makes it difficult to handle in an etching process. Therefore, strong oxidizing agents are typically used in conventional etching processes to form soluble or volatile ruthenium-oxide compounds.

[0007] Some commercially available ruthenium etchants contain strong oxidizing agents, such as sodium hypochlorite, ceric ammonium nitrate, and periodic acid, which oxidize the ruthenium surface to ruthenium tetroxide (RuO 4Of these chemicals, the most effective etchants, cerium ammonium nitrate and sodium hypochlorite, are problematic because they pose a risk of metal contamination in subsequently formed devices. For example, incorporation of trace amounts of sodium and cerium in the front-end-of-line can significantly degrade transistor performance. Periodic acid, on the other hand, is expensive and cannot be used to provide a cost-effective etching process for ruthenium.

[0008] Another problem with conventional etching processes used to etch ruthenium is that the surface tends to be rough after etching. This is because ruthenium grain boundaries tend to be much more reactive than grain surfaces, which leads to selective etching at grain boundaries compared to grain surfaces. Thus, chemical mechanical polishing is often used in conventional processes to smooth the ruthenium surface after etching.

[0009] Like ruthenium etch chemistries, conventional ruthenium CMP slurries generally rely on strong oxidizers to etch the ruthenium surface. As with etching, these oxidizers tend to react selectively to grain boundaries, which leads to pitting of the Ru surface during CMP. Less aggressive oxidizers can be used to reduce pitting, but the material removal rate is significantly lower when such oxidizers are used in CMP slurries. As the corrosion products are no longer soluble, the material removal rate is significantly reduced, and therefore mechanical polishing becomes the only process for material removal.

[0010] A need exists for new ruthenium CMP slurry chemistries that provide high material removal rates while improving post-etch surface smoothness. Summary of the Invention [Means for solving the problem]

[0011] The present disclosure provides a novel corrosion control chemistry for ruthenium (Ru) CMP processes. More specifically, the present disclosure provides a novel ruthenium CMP slurry chemistry that uses halogenation of the ruthenium surface to form ruthenium halide or ruthenium oxyhalide surface intermediates and reactive dissolution to chemically remove the ruthenium halide or ruthenium oxyhalide surface intermediates. The halogenation of the ruthenium surface can be achieved using radical halogenation of a chemical halogenating agent. The halogenation is self-limiting in itself, and the kinetics of reactive dissolution are temperature dependent. The self-limiting nature of the halogenation limits pitting of the ruthenium surface. The temperature-dependent kinetics of dissolution further aid in planarization of the ruthenium surface, since the mechanical polishing process increases the local temperature around high points on the surface.

[0012] According to one embodiment, an improved chemical mechanical polishing (CMP) process is provided herein for planarizing ruthenium surfaces. In the CMP process disclosed herein, a ruthenium surface (e.g., a post-etch ruthenium surface) may be exposed to a CMP slurry containing a halogenating agent that reacts with the ruthenium surface to form a ruthenium halide or oxyhalide surface, and a ligand for ligand-assisted reactive dissolution of the ruthenium halide or oxyhalide surface. The relative amounts of the halogenating agent and ligand in the CMP slurry may be controlled to provide a diffusion-limited etching process that improves the post-etch surface morphology while providing a high material removal rate.

[0013] For this process, a wide variety of halogenating agents (such as trichloroisocyanuric acid (TCCA)) can be used in non-aqueous solvents (such as ethyl acetate (EA)). Because ruthenium halide or oxyhalide surfaces are insoluble in non-aqueous solvents, ligand-assisted reactive dissolution is used to facilitate chemical removal of the ruthenium halide or oxyhalide surface. A wide variety of ligands (such as acetylacetone (ACAC) or aminopolycarboxylic acids) can be used for reactive dissolution of the ruthenium halide or oxyhalide surface.

[0014] According to another embodiment, a composition comprising a novel CMP slurry is provided herein. The novel CMP slurry may generally include 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. In some embodiments, the relative amounts of the halogenating agent and the ligand in the CMP slurry may be selected to result in a rate of halogenation of the ruthenium surface that is greater than the rate of dissolution of the ruthenium halide surface.

[0015] In some embodiments, the CMP slurries described herein include a halogenating agent but do not include an oxide-forming oxidizing agent. As used herein, an oxide-forming oxidizing agent is an oxidizing agent that reacts with a ruthenium surface to form a ruthenium-oxide layer on the ruthenium surface. Although a halogenating agent can halogenate and chemically oxidize a ruthenium surface, it does not react with the ruthenium surface to form a ruthenium-oxide layer on the ruthenium surface.

[0016] In other embodiments, the CMP slurry described herein may include a halogenating agent and an oxide-forming oxidizing agent. For example, the CMP slurry may further contain an amount of water or dissolved oxygen. When the halogenation is carried out in the presence of an oxide-forming oxidizing agent, such as water or dissolved oxygen, a ruthenium halide surface containing ruthenium-oxide-halogen species is formed on the ruthenium surface. The presence of ruthenium-oxide-halogen species increases the material removal rate in the CMP process because the ruthenium-oxide-halogen species are generally more soluble than the ruthenium halide surface layer.

[0017] In some embodiments, the halogenating agent included in the CMP slurry may be a chlorinating agent, in which case the chlorinating agent may react with the ruthenium surface to form a chlorinated ruthenium surface, and the ligand may be reactive towards the chlorinated ruthenium surface.

[0018] In some embodiments, the halogenating agent may include a chlorinating agent dissolved in a solvent. For example, the chlorinating agent may be trichloroisocyanuric acid (TCCA), oxalyl chloride, thionyl chloride, or N-chlorosuccinimide, and the solvent may be ethyl acetate, acetone, acetonitrile, or a chlorocarbon. In such embodiments, the halogenating agent reacts with the ruthenium surface to form a self-limiting RuCl 3 A passivation layer may be formed.

[0019] It should be noted that the halogenating agent disclosed herein is not strictly limited to a chlorinating agent. In some 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 fluorinated ruthenium surface, and the ligand may have reactivity toward the fluorinated ruthenium 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 brominated ruthenium surface, and the ligand may have reactivity toward the brominated ruthenium surface.

[0020] In some embodiments, the ligand included in the CMP slurry may include ethylenediaminetetraacetic acid (EDTA), acetylacetone (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 the ligand exchange reaction with the ruthenium halide surface are potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH 4 OH), and tetramethylammonium hydroxide (CH 3 ) 4 NOH).

[0021] In some embodiments, the CMP slurry may be non-aqueous and may include abrasive particles. In one exemplary implementation, the CMP slurry disclosed herein may use EA as a solvent and may include nanoparticle abrasives (e.g., silicon dioxide (SiO 2 )), a halogenating reagent (eg, TCCA), a ligand (eg, an aminopolycarboxylic acid), and a base to catalyze the ligand-assisted reactive dissolution.

[0022] Thus, the technology disclosed herein provides a ruthenium CMP process and a ruthenium CMP slurry that primarily uses halogenation to form ruthenium-halogen compounds on ruthenium surfaces and ligand-assisted reactive dissolution for chemical removal of the ruthenium-halogen compounds. Because different ligands react with halogenated surfaces at different rates, a variety of different ligands can be used to tailor the chemical etch rate achieved during a given CMP process. One advantage of the CMP process and CMP slurry described herein is that the chemical and mechanical properties of the ruthenium-halogen compounds are more suitable for CMP processes. Thus, the CMP process and CMP slurry described herein improve the smoothness of the ruthenium surface after etching while providing a high material removal rate.

[0023] As further described herein, the present disclosure provides various embodiments of methods utilizing the novel CMP chemistries disclosed herein to planarize ruthenium surfaces. It should be understood that the order of discussion of the various steps described herein is presented for clarity. In general, these steps can be performed in any suitable order. In addition, although each of the various features, techniques, configurations, etc. herein may be described in various places in the present disclosure, it is intended that each of these concepts can be practiced independently of one another or in combination with one another. Thus, the present invention can be embodied and viewed in many different ways.

[0024] According to one embodiment, a method of removing ruthenium is provided herein. The method generally begins with placing a substrate in a chemical mechanical polishing (CMP) system, the CMP system including a polishing pad mounted on a rotatable platen, whereby the polishing pad can be rotated and moved across a surface of the substrate, the substrate including a ruthenium surface. The method then can include dispensing a slurry onto the polishing pad. The slurry generally can include 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 can include polishing the ruthenium surface using the slurry until a predetermined amount of ruthenium is removed.

[0025] In some embodiments, the method can further include controlling the relative amounts of halogenation agent and ligand in the slurry such that the rate of halogenation of the ruthenium surface is greater than the rate of dissolution of the ruthenium halide surface.

[0026] In some embodiments, dispensing the slurry onto the polishing pad can include dispensing a slurry that does not include an oxide-forming oxidizing agent, hi other embodiments, dispensing the slurry onto the polishing pad can include dispensing a slurry that includes a halogenating agent and an oxide-forming oxidizing agent.

[0027] In some embodiments, the halogenating agent may include a chlorinating agent, which reacts with the ruthenium surface to form a chlorinated ruthenium surface. In such embodiments, the ligand may react with the chlorinated ruthenium surface to dissolve the chlorinated ruthenium surface. In some embodiments, the catalyst that increases the rate of the ligand exchange reaction with the chlorinated ruthenium surface may be a base.

[0028] It should be noted that this Summary section does not specify all embodiments and / or inherently novel aspects of the invention described in this disclosure or claims. Instead, this Summary provides only a preliminary discussion of various embodiments and corresponding novelties over the prior art. For further details and / or possible aspects of the invention and embodiments, please refer to the Detailed Description section and corresponding figures of the present disclosure detailed below.

[0029] The present invention and its advantages will be more fully understood by reference to the following description taken in conjunction with the accompanying drawings in which like reference numbers indicate like features, and in which it is to be noted, however, that the accompanying drawings merely illustrate exemplary embodiments of the disclosed concepts and therefore should not be considered as limiting the scope of the present invention, as the disclosed concepts may encompass other equally effective embodiments. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a block diagram of a chemical mechanical polishing (CMP) system. [Diagram 2] FIG. 1 is a flow diagram illustrating one embodiment of a method utilizing the techniques described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Etching ruthenium with liquid (wet) chemistries traditionally uses strong oxidizing agents to form soluble ruthenium species. Currently available Ru etchants include RuO 4 or the related hydrated species, metal Ru 0 Ru 8+ Conventional ruthenium wet etch processes use cerium ammonium nitrate, periodic acid, and hypochlorite ions to oxidize ruthenium to SiO2. However, these oxidations result in rough surfaces after etching due to the increased reactivity of ruthenium at the grain boundaries. Another weakness of conventional ruthenium wet etch processes is that the reaction products are highly soluble. This solubility leads to an oxidation-limited etch, which only exacerbates the formation of roughness during etching. These weaknesses are amplified when the same oxidizer is used as part of the Ru CMP slurry. Therefore, new etch chemistries are needed for use in Ru CMP for better ruthenium removal.

[0032] The present disclosure provides a novel CMP slurry chemistry for planarizing ruthenium (Ru) surfaces. As described in more detail below, the Ru CMP slurry described herein includes a halogenating agent that chemically modifies the ruthenium surface to form a ruthenium halide or oxyhalide passivation layer on the ruthenium surface, a ligand for reactive dissolution of the ruthenium halide or oxyhalide passivation layer, a strong base or other catalyst to increase the ligand reaction rate, and an abrasive grinding media in a non-aqueous solvent. Surfactants or other stabilizers may also be used to help keep all of these components dissolved or suspended in the CMP slurry.

[0033] Unlike conventional CMP slurry chemistries used to planarize ruthenium, the CMP slurry chemistries disclosed herein planarize Ru at a lower oxidation state than the higher oxidation state achieved in conventional Ru CMP slurries. 0 Ru3+ The use of lower oxidation states has the advantage of providing options for forming soluble and insoluble ruthenium products. The CMP slurry chemistries disclosed herein achieve the lower oxidation states primarily by using halogenation, rather than oxidation, of the ruthenium surface to form a passivation layer of ruthenium halide or oxyhalide. Metal Ru 0 Direct halogenation of Ru 3+ X 3 (X is a halogen). In some embodiments, halogenation can be achieved by exposing the ruthenium surface to a CMP slurry that includes a chlorinating, fluorinating, or brominating agent.

[0034] Chlorination of the ruthenium surface can be achieved using a wide variety of chlorinating agents, such as trichloroisocyanuric acid (TCCA), oxalyl chloride, thionyl chloride, and N-chlorosuccinimide. Exposure of the ruthenium surface to these chlorinating agents chemically modifies the ruthenium surface to form ruthenium trichloride (RuCl 3 A ruthenium chloride passivation layer is formed, such as, but not limited to, ruthenium chloride chlorinating agents. It is noted that this is not an exhaustive list of all possible chlorinating agents that can be used to form a ruthenium chloride passivation layer. It is further noted that the ruthenium surface can be exposed to other halogenating agents to form other ruthenium halide or oxyhalide passivation layers. For example, fluorination or bromination of the ruthenium surface 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 generally hydrolyzed in water. Therefore, regardless of the halogenating agent used, the halogenation must occur in a solvent or solvent blend in which hydrolysis does not occur.

[0035] In one exemplary embodiment, a CMP slurry according to the present disclosure may include TCCA dissolved in a non-aqueous solvent such as ethyl acetate (EA), acetone, acetonitrile, or a chlorocarbon. When exposed to TCCA in a non-aqueous solvent such as ethyl acetate, Ru 0 reacts rapidly to form a self-limiting ruthenium chloride (RuCl 3 ) passivation layer is formed. If an oxide-forming oxidant, such as water or dissolved oxygen, is present during the chlorination reaction, the self-limiting ruthenium chloride passivation layer forms, RuO x Cl y The ruthenium chloride passivation layer, once formed, can be solubilized via a ligand exchange reaction. The addition of reactive ligands to the non-aqueous TCCA solution converts the CMP slurry chemistry described herein from a self-limiting surface passivation to a continuous etching process.

[0036] A wide variety of ligands may be used in CMP slurries to chemically remove the ruthenium chloride passivation layer via ligand-assisted reactive dissolution. For example, ligands such as acetylacetone (ACAC) or aminopolycarboxylic acid ligands dissolve the insoluble RuCl 3 Ethylenediaminetetraacetic acid (EDTA) works well for ligand-assisted dissolution of RuCl. 3 is an exemplary aminopolycarboxylic acid that reacts with insoluble RuCl to form a ruthenium aminopolycarboxylate. 3Alternative ligands for reactive dissolution of include, but are not limited to, iminodiacetic 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, dimethylsulfoxide (DMSO), or other organic solvents. In some embodiments, the ligands included in the CMP slurry can be used to tailor the chemical etch rate achieved during a given CMP process. For example, different ligands react with a ruthenium chloride passivation layer (or other ruthenium halide surface layer) at different rates. Since the kinetics of the reaction are highly dependent on the reactivity of the ligand used, different ligands can be selected and used to tailor the chemical etch rate achieved during a given CMP process.

[0037] The ligand exchange reaction (e.g., replacing EDTA with Cl ligand) is base catalyzed. Therefore, a base is required in the CMP slurry to deprotonate EDTA (or ACAC) to form the reactive anionic form of the ligand. Potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH 4 OH), tetramethylammonium hydroxide ((CH 3 ) 4 A wide variety of bases can be used, such as ammonium hydroxide, NOH, and other strong bases. Non-aqueous bases (e.g., quaternary ammonium hydroxides, trialkylamines) or basic solvents (e.g., amino alcohols) can also be used.

[0038] Thus, in one embodiment, the CMP slurries described herein promote a chlorination reaction with the ruthenium surface to form ruthenium chloride (e.g., RuCl) on the ruthenium surface. 3) TCCA to form a passivation layer, a ligand such as ACAC or EDTA for ligand-assisted reactive dissolution of the ruthenium chloride passivation layer, and a base or other catalyst to increase the rate of the ligand reaction and subsequently etch the ruthenium surface. By varying the concentrations of TCCA and ligand in the slurry solution, the relative kinetic rates of the chlorination and ligand-assisted dissolution reactions can be adjusted.

[0039] As mentioned above, conventional ruthenium wet etch chemistries and CMP slurries rely on oxidation-limited etching, which increases surface roughness during etching and planarization. In contrast, the techniques described herein improve the post-etch surface morphology by ensuring that the overall etch reaction is dissolution-limited (i.e., by ensuring that the halogenation rate is much faster than the ligand-assisted dissolution rate). This is possible with the techniques described herein because the kinetics of halogenation and dissolution can be independently controlled by adjusting the relative amounts of halogenating agent and ligand contained in the CMP slurry such that the rate of halogenation of the ruthenium surface is greater than the dissolution rate of the ruthenium halide surface. Currently available oxidant-based etch chemistries lack this independent control.

[0040] In some embodiments, the CMP slurries described herein include a halogenating agent but do not include an oxide-forming oxidizing agent, such as water or dissolved oxygen. In other embodiments, the CMP slurries may contain both a halogenating agent and an oxide-forming oxidizing agent. In one exemplary embodiment, the CMP slurries described above may further include an amount of water or dissolved oxygen. When the chlorination is performed in the presence of an oxide-forming oxidizing agent, such as water or dissolved oxygen, RuO x Cl y Ruthenium chloride containing species (e.g., RuCl 3 ) A passivation layer is formed on the ruthenium surface. RuO x Cl yThe species is generally more soluble than the ruthenium chloride passivation layer, so RuO x Cl y The presence of the seeds increases the material removal rate achieved in the CMP process.

[0041] In addition to the liquid components mentioned above, the CMP slurries described herein may also contain an abrasive medium, such as silica, alumina, ceria, or other nanoparticles, to mechanically polish the ruthenium surface. This mechanical polishing increases the local temperature at elevated locations on the wafer surface. This local heating is responsible for increasing the etch kinetics, which aids in the planarization of the wafer. 3 Because the ligand exchange reactions used to solubilize the are very sensitive to temperature, the localized heating that occurs at elevated locations is very effective in increasing the local etch rate in those regions.

[0042] The present disclosure provides a novel CMP slurry as well as an improved CMP process, which utilizes the CMP slurry chemistry disclosed herein to planarize ruthenium surfaces. The CMP process disclosed herein can be used in a wide variety of CMP tools and systems. FIG. 1 shows an embodiment of a CMP system 100 that includes a polishing pad 105 mounted on top of a rotatable platen 110 and a slurry dispenser 115 for dispensing a slurry 120 on top of the polishing pad 105. As the platen 110 rotates, the motion of the platen 110 dispenses 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 can rotate and move radially along the platen 110. A pad conditioner 135 is used to maintain pad flatness and surface quality. The techniques described herein include improved slurry chemistry as part of the chemically reactive portion of the chemical mechanical material removal. As mentioned, Figure 1 shows one exemplary CMP system. It will be appreciated by those skilled in the art that the techniques, methods, processes and slurry chemistry described herein may be used in a wide variety of CMP tools and systems and are not limited to those shown in Figure 1.

[0043] Finally, the present disclosure provides various methods that utilize the novel CMP slurry chemistries and CMP processes disclosed herein. Figure 2 illustrates one embodiment of a method that utilizes the techniques described herein to planarize or remove ruthenium from the surface of a substrate. It will be understood that the embodiment of Figure 2 is merely exemplary and that additional methods may utilize the techniques described herein. Additionally, additional processing steps may be added to the method illustrated in Figure 2, as the steps described are not intended to be exclusive. Additionally, the order of steps is not limited to the order shown in the figure, as different orders may occur and / or various steps may be combined or performed simultaneously.

[0044] FIG 2 illustrates one embodiment of a method 200 for removing ruthenium. Method 200 may generally begin with placing a substrate in a chemical mechanical polishing (CMP) system (at step 210). FIG 1 illustrates one embodiment of a CMP system (or CMP tool) in which a substrate may be placed at step 210. As discussed above and shown in FIG 1, a CMP system 100 may generally include a polishing pad 105 mounted on a rotatable platen 110, which may rotate and move across a substrate surface. In some embodiments, the substrate may include a ruthenium surface.

[0045] Next, method 200 may include dispensing a slurry onto the polishing pad (at step 220). As discussed above, the slurry may generally include a solvent, a halogenating agent that halogenates the ruthenium surface to form a ruthenium halide surface, a ligand that reacts with and dissolves the ruthenium halide surface, and a catalyst that increases the rate of the ligand exchange reaction with the ruthenium halide surface. In some embodiments, method 200 may include controlling the relative amounts of halogenating agent and ligand included in the slurry such that the rate of halogenation of the ruthenium surface is greater than the rate of dissolution of the ruthenium halide surface.

[0046] Next, the method 200 may include polishing the ruthenium surface with a slurry until a predetermined amount of the ruthenium is removed (at step 230).

[0047] It should be noted that the phrase "one embodiment" or "one embodiment" used throughout this specification means that a particular feature, structure, material, or characteristic described with respect to that embodiment is included in at least one embodiment of the invention, but does not imply that they are present in all embodiments. Thus, the appearance of "in one embodiment" or "in one embodiment" in various places throughout this specification does not necessarily refer to the same embodiment of the invention. Moreover, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. In other embodiments, various additional layers and / or structures may be included and / or described features may be omitted.

[0048] As used herein, the term "substrate" refers to and includes a base material or structure on which a material is formed. It will be understood that a substrate may include a single material, multiple layers of different materials, a single layer or multiple layers having regions of different materials or structures therein, and the like. These materials may include semiconductors, insulators, conductors, or combinations thereof. For example, a substrate may be a semiconductor substrate with one or more layers, structures, or regions formed thereon, a base semiconductor layer on a supporting structure, a metal electrode, or a semiconductor substrate. The substrate may be a conventional silicon substrate or other bulk substrate including a layer of semiconducting material. As used herein, the term "bulk substrate" refers to and includes silicon wafers, as well as silicon-on-insulator ("SOI") substrates such as silicon-on-sapphire ("SOS") substrates and silicon-on-glass ("SOG") substrates, epitaxial layers of silicon on a base semiconductor substrate, and other semiconductor or optoelectronic materials such as silicon germanium, germanium, gallium arsenide, gallium nitride, and indium phosphide. The substrate may be doped or undoped.

[0049] Systems and methods for planarizing a surface of a substrate are described in various embodiments. The substrate may include any material portion or structure of a device, particularly a semiconductor or other electronic device, and may be a base substrate structure, such as a semiconductor substrate, or a layer on or overlying the base substrate structure, such as a thin film. Thus, substrate is not intended to be limited to any particular base structure, underlying layer, or overlying layer, patterned or unpatterned, but rather is intended to include any such layer or base structure, and any combination of layers and / or base structures.

[0050] Those skilled in the art will appreciate that various embodiments may be practiced without one or more of the specific details, or with other alternative and / or additional methods, materials, or components. In other instances, well-known structural, material, or operational details have not been shown or described so as not to obscure aspects of the various embodiments of the invention. Similarly, for purposes of explanation, specific numbers, materials, and configurations have been set forth to provide a thorough understanding of the invention. Nevertheless, the invention may be practiced without the specific details. Additionally, it should be understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

[0051] Further variations and alternative embodiments of the described systems and methods will be apparent to those skilled in the art upon consideration of this specification. It will therefore be appreciated that the described systems and methods are not limited by these exemplary configurations. It should be understood that the forms of the systems and methods shown and described herein should be considered as exemplary embodiments. Various modifications to the implementations may be made. Thus, although the ruthenium CMP technique is described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the disclosure. Thus, the specification and drawings should be considered in an illustrative rather than a restrictive sense, and such modifications are intended to be included within the scope of the disclosure. Furthermore, any benefits, advantages, or solutions to problems described herein with respect to specific embodiments are not intended to be construed as any or all of the essential, necessary, or essential features or elements of the claims.

[0052] Those skilled in the art will also appreciate that many variations may be made in the operation of the techniques described above while still achieving the same objectives of the present invention. Such variations are intended to be included within the scope of the present disclosure. Accordingly, the above description of embodiments of the present invention is not intended to be limiting. Rather, any limitations to embodiments of the present invention are presented in the following claims.

Claims

1. 1. A composition comprising: having a chemical mechanical polishing (CMP) slurry; The CMP slurry is A non-aqueous solvent; a halogenating agent that halogenates a ruthenium surface to form a halogenated ruthenium surface, the halogenated ruthenium surface being insoluble in the non-aqueous solvent; a ligand that reacts with the halogenated ruthenium surface to dissolve the halogenated ruthenium surface; a catalyst that enhances the rate of ligand exchange reactions with the halogenated ruthenium surface; having The CMP slurry does not include an oxide-forming oxidizing agent.

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

3. The composition of claim 1 , wherein the CMP slurry comprises abrasive particles.

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

5. The composition of claim 1, wherein the CMP slurry limits the oxidation state of the ruthenium surface to Ru 3+ by containing the halogenating agent and not containing the oxide-forming oxidizing agent in the CMP slurry.

6. 10. The composition of claim 1, wherein the CMP slurry does not contain water, dissolved oxygen, or another oxide-forming oxidizing agent.

7. The halogenating agent reacts with the ruthenium surface to form self-limiting ruthenium trichloride (RuCl ３ 2. The composition of claim 1 which forms a passivation layer.

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

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

10. the halogenating agent is a chlorinating agent, the chlorinating agent reacts with the ruthenium surface to form a chlorinated ruthenium surface; The composition of claim 1 , wherein the ligand is reactive towards the chlorinated ruthenium surface.

11. the halogenating agent is a fluorinating agent, the fluorinating agent reacts with the ruthenium surface to form a fluorinated ruthenium surface; The composition of claim 1 , wherein the ligand is reactive toward the fluorinated ruthenium surface.

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

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

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

15. The base is potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH ４ OH), or tetramethylammonium hydroxide ((CH ３ ) ４ The composition of claim 14 comprising:

16. The composition of claim 1, wherein the ligand reacts with the halogenated ruthenium surface to render the halogenated ruthenium surface soluble via the ligand exchange reaction and provide ligand-assisted reactive dissolution of the halogenated ruthenium surface.

17. The method of claim 17, wherein the halogenating agent in the non-aqueous solvent reacts with the ruthenium surface to form a self-limiting ruthenium halide passivation layer; 10. The composition of claim 1, wherein said ligand converts a CMP process using said CMP slurry from a self-limiting surface passivation to a continuous etching process.

18. The catalyst is a base, 20. The composition of claim 17, wherein the base deprotonates the ligand to enhance the rate of the ligand exchange reaction with the halogenated ruthenium surface and subsequently etches the ruthenium surface.

19. A method for removing ruthenium, the method comprising: placing a substrate in a chemical mechanical polishing (CMP) system, the CMP system having a polishing pad mounted on a rotatable platen, the polishing pad being rotatable and capable of moving across a surface of the substrate, the substrate comprising a ruthenium surface; Dispensing a slurry onto the polishing pad, the slurry comprising: A non-aqueous solvent; a halogenating agent that halogenates the ruthenium surface to form a halogenated ruthenium surface, the halogenated ruthenium surface being insoluble in the non-aqueous solvent; a ligand that reacts with the halogenated ruthenium surface to dissolve the halogenated ruthenium surface; a catalyst that enhances the rate of ligand exchange reactions with the halogenated ruthenium surface; having the slurry does not contain an oxide former; polishing the ruthenium surface with the slurry until a predetermined amount of ruthenium is removed; The method comprising:

20. The method of claim 20, further comprising the step of controlling the relative amounts of said halogenating agent and said ligand in said slurry, 20. The method of claim 19, wherein the rate of halogenation of the ruthenium surface is greater than the rate of dissolution of the halogenated ruthenium surface.

21. The halogenating agent comprises a chlorinating agent which reacts with the ruthenium surface to form a chlorinated ruthenium surface; 21. The method of claim 20, wherein the ligand reacts with the chlorinated ruthenium surface to dissolve the chlorinated ruthenium surface.

22. The halogenating agent comprises a chlorinating agent which reacts with the ruthenium surface to form a chlorinated ruthenium surface; 20. The method of claim 19, wherein the ligand reacts with the chlorinated ruthenium surface to dissolve the chlorinated ruthenium surface.

23. The method of claim 19, wherein the catalyst is a base.

24. The method of claim 23, wherein the base comprises potassium hydroxide (KOH), sodium hydroxide (NaOH), ammonium hydroxide (NH 4 OH), or tetramethylammonium hydroxide ((CH 3 ) 4 NOH).

25. The slurry, wherein the slurry is non-aqueous; 20. The method of claim 19, wherein the non-aqueous slurry inhibits hydrolysis of the halogenating agent.

26. The method of claim 19, wherein the slurry contains abrasive particles.

27. The method of claim 19, wherein the slurry limits the oxidation state of the ruthenium surface to Ru 3+ by including the halogenating agent and not including the oxide-forming oxidizing agent in the slurry.

28. The method of claim 19, wherein the slurry does not contain water, dissolved oxygen, or another oxide-forming oxidizing agent.

29. The method of claim 19, wherein the halogenating agent reacts with the ruthenium surface to form a self-limiting ruthenium trichloride (RuCl 3 ) passivation layer.

30. The method of claim 19, wherein the halogenating agent comprises trichloroisocyanuric acid (TCCA), oxalyl chloride, thionyl chloride, or N-chlorosuccinimide.

31. The method of claim 19, wherein the non-aqueous solvent is ethyl acetate, acetone, acetonitrile, or a chlorocarbon.

32. The halogenating agent is a fluorinating agent, the fluorinating agent reacts with the ruthenium surface to form a fluorinated ruthenium surface; 20. The method of claim 19, wherein the ligand is reactive towards the fluorinated ruthenium surface.

33. The halogenating agent is a brominating agent, the brominating agent reacts with the ruthenium surface to form a brominated ruthenium surface; 20. The method of claim 19, wherein the ligand is reactive towards the ruthenium bromide surface.

34. The method of claim 19, wherein the ligand comprises ethylenediaminetetraacetic acid (EDTA), acetylacetone (ACAC), iminodiacetic acid (IDA), or diethylenetriaminepentaacetic acid (DTPA).

35. The method of claim 19, wherein the ligand reacts with the halogenated ruthenium surface to render the halogenated ruthenium surface soluble via the ligand exchange reaction and provide ligand-assisted reactive dissolution of the halogenated ruthenium surface.

36. The method of claim 35, further comprising the step of controlling the relative amounts of the halogenating agent and the ligand in the slurry so that the rate of halogenation of the ruthenium surface is greater than the rate of dissolution of the halogenated ruthenium surface.

37. The halogenating agent comprises a chlorinating agent, the chlorinating agent reacts with the ruthenium surface to form a chlorinated ruthenium surface; 37. The method of claim 36, wherein the ligand reacts with the chlorinated ruthenium surface to dissolve the chlorinated ruthenium surface.

38. The method of claim 37, wherein the halogenating agent in the non-aqueous solvent reacts with the ruthenium surface to form a self-limiting ruthenium halide passivation layer; 20. The method of claim 19, wherein the ligand converts the method for removing ruthenium from a self-limiting surface passivation to a continuous etching process.

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