Etching solution, method for producing etching solution, method for treating object, and method for producing ruthenium-containing wiring

Abstract

To provide: an etchant which is practical for a ruthenium etching process and reduced in the risk of production of ruthenium tetraoxide; a manufacturing method thereof; and a method for processing a workpiece and a method for manufacturing a ruthenium-containing wiring line, which are arranged to use the etchant.SOLUTION: An etchant for performing an etching process of ruthenium comprises orthoperiodic acid; and ammonia, which is pH8 or above and pH10 or below. A method for manufacturing the etchant is also disclosed. A method for processing a workpiece by use of the etchant comprises the step of performing an etching process of a workpiece containing ruthenium. A method for manufacturing a ruthenium-containing wiring line comprises the step of applying the etchant to a substrate including, in a surface layer, a region formed by an insulation film and a region formed by ruthenium, thereby selectively etching the region formed by ruthenium.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an etching solution, a method for producing the etching solution, a method for treating an object to be treated, and a method for producing a ruthenium-containing wiring. [Background technology]

[0002] The manufacturing process of semiconductor devices consists of various multi-stage processing steps. Such processing steps include the process of patterning semiconductor layers and electrodes by etching, etc. In recent years, with the progress of high integration and high speed of semiconductor devices, ruthenium (Ru) is sometimes used for wiring, etc. In this case, ruthenium is the target to be etched.

[0003] As a ruthenium etching solution for etching ruthenium, for example, one containing orthoperiodic acid as an oxidizing agent has been proposed (Patent Documents 1 and 2). In addition, Patent Document 3 describes a ruthenium etching solution containing orthoperiodic acid and ammonia and having a pH of 4.5 (Table 1, Example A32). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 68183 [Patent Document 2] JP 2016-92101 A [Patent Document 3] International Publication No. 2019 / 138814 Summary of the Invention [Problem to be solved by the invention]

[0005] In the etching process in the manufacturing process of semiconductor devices, if the etching rate is too low, the etching process takes a long time and is not practical. In addition, when an etching solution such as that described in Patent Document 3 is used, contact between the etching solution and ruthenium produces toxic ruthenium tetroxide (RuO 4 ) may be generated. Therefore, there is a demand for a ruthenium etchant that has an industrially practical etching rate and suppresses the production of ruthenium tetroxide. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an etching solution that is practical for a ruthenium etching process and has a reduced risk of generating ruthenium tetroxide, a method for producing the etching solution, a method for treating a workpiece using the etching solution, and a method for producing a ruthenium-containing wiring. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following configuration.

[0007] A first aspect of the present invention is an etching solution for etching ruthenium, comprising orthoperiodic acid and ammonia, and having a pH of 8 or more and 10 or less.

[0008] A second aspect of the present invention is a method for producing the etching solution, comprising the steps of mixing a solution containing orthoperiodic acid and ammonia water to prepare a mixed solution, adjusting the pH of the mixed solution to 8 or more and 10 or less, and filtering the mixed solution through a filter, in this order.

[0009] A third aspect of the present invention is a method for treating an object to be treated, comprising the step of etching the object to be treated containing ruthenium with the etching solution.

[0010] A fourth aspect of the present invention is a method for producing a ruthenium-containing wiring, comprising the step of selectively etching the region composed of ruthenium by applying the etching solution to a substrate including a region composed of an insulating film and a region composed of ruthenium on a surface layer. Effect of the Invention

[0011] According to the present invention, it is possible to provide an etching solution that is practical for a ruthenium etching process and has a reduced risk of generating ruthenium tetroxide, a method for producing the etching solution, a method for treating a workpiece using the etching solution, and a method for producing a ruthenium-containing wiring. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an example of a substrate having a ruthenium-containing wiring, which is an object to be processed in a recess etching process; [Diagram 2] FIG. 13 is a schematic diagram showing an example of a wiring substrate after recess etching processing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (etchant) The etching solution according to a first aspect of the present invention is characterized in that it contains orthoperiodic acid and ammonia, and has a pH of 8 or more and 10 or less. The etching solution according to this aspect is used for etching ruthenium.

[0014] <Orthoperiodic acid> The etching solution according to the present embodiment is orthoperiodic acid (H 5 IO 6 ).

[0015] The content of orthoperiodic acid in the etching solution of the present embodiment is not particularly limited, but is, for example, 0.05 to 8 mass% relative to the total mass of the etching solution, preferably 0.1 to 7 mass%, more preferably 0.5 to 5 mass%, and even more preferably 0.5 to 3 mass%. When the content of orthoperiodic acid is within the above range, the etching rate for ruthenium is further improved.

[0016] <Ammonia> The etching solution according to the present embodiment is ammonia (NH 3 ). The content of ammonia in the etching solution of this embodiment is not particularly limited, and may be set to a content that makes the pH of the etching solution of this embodiment 8 or more depending on the content of the orthoperiodic acid and the amount of other pH adjusters added as necessary. Preferably, ammonia is used in a content that makes the etching solution of this embodiment have a preferred pH range described below. The content of ammonia may be, for example, 5 to 150 parts by mass, preferably 10 to 100 parts by mass, and more preferably 15 to 75 parts by mass, relative to 100 parts by mass of orthoperiodic acid. When the content of ammonia is within the above range, the etching rate for ruthenium is not too low, and the generation of ruthenium tetroxide is reduced.

[0017] <Other ingredients> The etching solution of the present embodiment may contain other components in addition to the above components, as long as the effects of the present invention are not impaired. Examples of the other components include water, a water-soluble organic solvent, a pH adjuster, a surfactant, and an oxidizing agent.

[0018] Furthermore, the etching liquid of the present embodiment may contain a slurry (metal oxide particles) such as that used in a CMP (Chemical Mechanical Polishing) process, or may not contain such a slurry (metal oxide particles). However, when the etching solution of this embodiment is used for applications such as forming ruthenium wiring by applying the etching solution of this embodiment through a mask to a thin ruthenium film disposed on a substrate, it is preferable that the etching solution does not contain such a slurry (metal oxide particles) from the viewpoint of process stability. The etching solution of the present embodiment preferably does not contain an abrasive. The abrasive is, for example, a metal oxide particle such as alumina, silica, titania, ceria, or zirconia. The etching solution of the present embodiment preferably does not contain these metal oxide particles.

[0019] ·water The etching solution of the present embodiment preferably contains water as a solvent for the above components. The water may contain trace components that are inevitably mixed in. The water used in the etching solution of the present embodiment is preferably water that has been subjected to a purification treatment, such as distilled water, ion-exchanged water, or ultrapure water, and it is more preferable to use ultrapure water that is generally used in semiconductor manufacturing. The content of water in the etching solution of this embodiment is not particularly limited, but is preferably 80 mass% or more, more preferably 90 mass% or more, and even more preferably 94 mass% or more. The upper limit is not particularly limited, but is preferably less than 99.95 mass%, more preferably 99.9 mass% or less, and even more preferably 99.5 mass% or less. The etching solution of this embodiment is preferably an aqueous solution in which the orthoperiodic acid is dissolved in water and the pH is adjusted to 8 to 10 with ammonia.

[0020] Water-soluble organic solvents The etching solution of the present embodiment may contain a water-soluble organic solvent within a range that does not impair the effects of the present invention. Examples of the water-soluble organic solvent include alcohols (e.g., methanol, ethanol, ethylene glycol, propylene glycol, glycerin, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, furfuryl alcohol, and 2-methyl-2,4-pentanediol), dimethyl sulfoxide, and ethers (e.g., ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and propylene glycol dimethyl ether).

[0021] When the etching solution of the present embodiment contains a water-soluble organic solvent, the content of the water-soluble organic solvent is preferably 50 mass % or less, more preferably 30 mass % or less, and even more preferably 10 mass % or less, based on the total amount of water and the water-soluble organic solvent.

[0022] pH adjuster The etching solution of the present embodiment may contain a pH adjuster within the scope of the present invention. In this specification, the term "pH adjuster" refers to a component other than the above-mentioned ammonia that can adjust the pH of the solution. The amount of the additive is arbitrary and may be selected so as to achieve the pH described below.

[0023] The pH adjuster may be an acidic or alkaline compound, and suitable examples of the acidic compound include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and salts thereof, and organic acids such as acetic acid, lactic acid, oxalic acid, tartaric acid, and citric acid, and salts thereof.

[0024] As for the alkaline compound, organic alkaline compounds and inorganic alkaline compounds can be used. Suitable examples of the organic alkaline compound include quaternary ammonium salts such as organic quaternary ammonium hydroxides, and salts of alkylamines such as trimethylamine and triethylamine and their derivatives.

[0025] Specific examples of the organic quaternary ammonium hydroxide include tetramethylammonium hydroxide (TMAH), bis(2-hydroxyethyl)dimethylammonium hydroxide, tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, trimethyl(hydroxyethyl)ammonium hydroxide, and triethyl(hydroxyethyl)ammonium hydroxide.

[0026] Examples of inorganic alkaline compounds include inorganic compounds containing alkali metals or alkaline earth metals and their salts, such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

[0027] Surfactants The etching solution of the present embodiment may contain a surfactant for the purpose of adjusting the wettability of the etching solution to the object to be treated, etc. As the surfactant, a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant may be used, and these may be used in combination.

[0028] Examples of nonionic surfactants include polyalkylene oxide alkyl phenyl ether surfactants, polyalkylene oxide alkyl ether surfactants, block polymer surfactants consisting of polyethylene oxide and polypropylene oxide, polyoxyalkylene distyrene-type phenyl ether surfactants, polyalkylene tribenzyl phenyl ether surfactants, and acetylene polyalkylene oxide surfactants.

[0029] Examples of anionic surfactants include alkylsulfonic acids, alkylbenzenesulfonic acids, alkylnaphthalenesulfonic acids, alkyldiphenylethersulfonic acids, fatty acid amidesulfonic acids, polyoxyethylene alkylether carboxylic acids, polyoxyethylene alkylether acetic acids, polyoxyethylene alkylether propionic acids, alkylphosphonic acids, and salts of fatty acids. Examples of "salts" include ammonium salts, sodium salts, potassium salts, and tetramethylammonium salts.

[0030] Examples of cationic surfactants include quaternary ammonium salt surfactants and alkylpyridinium surfactants.

[0031] Examples of amphoteric surfactants include betaine type surfactants, amino acid type surfactants, imidazoline type surfactants, and amine oxide type surfactants.

[0032] These surfactants are generally commercially available. The surfactants may be used alone or in combination of two or more.

[0033] Oxidizing agents The etching solution of the present embodiment may contain, in addition to the above-mentioned orthoperiodic acid, other oxidizing agents, such as transition metal oxides, peroxides, cerium ammonium nitrate, nitrates, nitrites, iodic acid, iodates, periodates, perchlorates, persulfuric acid, persulfates, peracetic acid, peracetates, permanganate compounds, and dichromate compounds.

[0034] <ph> The etching solution of this embodiment is characterized by having a pH of 8 or more and 10 or less. By adjusting the pH to 8 or more and 10 or less using ammonia as a pH adjuster, a practical etching rate for ruthenium can be maintained and the risk of generating ruthenium tetroxide can be reduced. From the viewpoint of the etching rate, the etching solution of this embodiment preferably has a pH of 9.5 or less, more preferably a pH of 9.0 or less, and even more preferably a pH of 8.5 or less. From the viewpoint of further reducing the risk of generating ruthenium tetroxide, the etching solution of this embodiment preferably has a pH of more than 8. The pH range of the etching solution of this embodiment is preferably a pH of 8 or more and 9.5 or less, more preferably a pH of 8 or more and 9.0 or less, and even more preferably a pH of 8 or more and 8.5 or less. In addition, the pH range of the etching solution of this embodiment is preferably a pH of more than 8 and 9.5 or less, more preferably a pH of more than 8 and 9.0 or less, and even more preferably a pH of more than 8 and 8.5 or less. The pH value is measured using a pH meter under conditions of room temperature (23° C.) and normal pressure (1 atm).

[0035] <Number of particles larger than 100 nm> In the etching solution of this embodiment, the number of particles larger than 100 nm is preferably 20 / mL or less. The number of particles larger than 100 nm is preferably 15 / mL or less, more preferably 10 / mL or less, and even more preferably 5 / mL or less. By making the number of particles larger than 100 nm equal to or less than the upper limit, for example, when the etching solution is applied to a process of selectively etching a region composed of ruthenium on a substrate including a region composed of an insulating film and a region composed of ruthenium on the surface layer as described below, the risk of particles getting into the ruthenium that becomes a recess can be reduced. The number of particles larger than 100 nm in 1 mL of the etching solution can be measured by a light scattering type liquid-borne particle detector. As the light scattering type liquid-borne particle detector, for example, KS-19F manufactured by Rion Co., Ltd. can be mentioned.

[0036] <Object to be treated> The etching solution of this embodiment is used for etching ruthenium, and the target of the etching process is a target object containing ruthenium. The target object is not particularly limited as long as it contains ruthenium, and examples thereof include a substrate having a ruthenium-containing layer (ruthenium-containing film). The substrate is not particularly limited, and examples thereof include various substrates such as a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, and a substrate for a magneto-optical disk. The substrate is preferably a substrate used for manufacturing a semiconductor device. In addition to the ruthenium-containing layer and the substrate base material, the substrate may have various layers and structures, such as metal wiring, a gate structure, a source structure, a drain structure, an insulating layer, a ferromagnetic layer, and a non-magnetic layer, as appropriate. In addition, the top layer of the device surface of the substrate does not need to be a ruthenium-containing layer, and for example, the intermediate layer of a multilayer structure may be a ruthenium-containing layer. The size, thickness, shape, layer structure, etc. of the substrate are not particularly limited and can be appropriately selected depending on the purpose.

[0037] The ruthenium-containing layer is preferably a layer containing ruthenium metal, more preferably a ruthenium metal film. The thickness of the ruthenium-containing layer on the substrate is not particularly limited and can be appropriately selected according to the purpose. The thickness of the ruthenium-containing layer is, for example, in the range of 1 to 500 nm or 1 to 300 nm.

[0038] <Application>

[0039] The etching solution of the present embodiment may be used for microfabrication of a ruthenium-containing layer on a substrate, may be used for removing a ruthenium-containing deposit attached to a substrate, or may be used for removing impurities such as particles from a workpiece having a ruthenium-containing layer on the surface thereof.

[0040] More specifically, the use of the etching solution of this embodiment includes, for example, selective etching of the region made of ruthenium in a substrate that includes a region made of an insulating film and a region made of ruthenium on the surface (recess etching of ruthenium-containing wiring arranged on a substrate); removal of the ruthenium-containing film from the outer edge of the substrate on which the ruthenium-containing film is arranged; removal of the ruthenium-containing material adhering to the back surface of the substrate on which the ruthenium-containing film is arranged; removal of the ruthenium-containing material on the substrate after dry etching; removal of the ruthenium-containing material on the substrate after CMP processing. However, the etching solution of one aspect of this embodiment is not used for CMP processing.

[0041] <Recess Etching Process> The etching solution of this embodiment is preferably used for selectively etching the area composed of ruthenium in a substrate including an area composed of an insulating film and an area composed of ruthenium on the surface. A specific example of this process is recess etching of a ruthenium-containing wiring arranged on a substrate. The "recess etching process" means a process of forming a recess (recess) in the ruthenium-containing wiring arrangement portion on the substrate by etching the ruthenium-containing wiring arranged on the substrate (manufacturing a ruthenium-containing wiring having a recess). In particular, when the number of particles larger than 100 nm contained in the etching solution of this embodiment is 20 pieces / mL or less, the etching solution of this embodiment is suitable for recess etching of a ruthenium-containing wiring arranged on a substrate. In the recess etching process of a ruthenium-containing wiring, there is a concern that impurity particles contained in the etching solution may enter the recess, and it is also difficult to remove the impurity particles. By performing recess etching using an etching solution in which the number of particles larger than 100 nm is 20 pieces / mL or less, such a risk can be reduced.

[0042] 1 is a schematic diagram showing an example of a substrate (hereinafter, also referred to as a "wiring substrate") having a ruthenium-containing wiring, which is an object to be processed in a recess etching process. The wiring substrate 1 has a substrate 3, an underlayer 4 on the substrate, an insulating film 5 having a trench 8 arranged on the underlayer 4, a barrier metal layer 6 arranged along the inner wall of the trench 8, and a ruthenium-containing wiring 7 filled inside the trench. In the wiring substrate 1, the insulating film 5 forms a region made of the insulating film. The ruthenium-containing wiring 7 forms a region made of ruthenium.

[0043] The thickness, shape, layer structure, etc. of the substrate 3 are not particularly limited and can be appropriately selected. Examples of the substrate 3 include various substrates such as a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, and a substrate for a magneto-optical disk. Examples of materials constituting the semiconductor substrate include silicon, silicon germanium, and III-V group compounds such as GaAs, as well as any combination thereof. In addition to the above configuration, the substrate 3 may have any suitable structure. For example, the substrate 3 may have metal wiring, gate electrodes, source electrodes, drain electrodes, insulating layers, ferromagnetic layers, non-magnetic layers, etc. The substrate 3 may have exposed integrated circuit structures, such as interconnect features, such as metal wiring and dielectric materials. Metals and alloys used for interconnect features include, for example, aluminum, copper-aluminum alloys, copper, titanium, tantalum, cobalt, silicon, titanium nitride, tantalum nitride, and tungsten. The substrate 3 may have layers of silicon oxide, silicon nitride, silicon carbide, and / or carbon-doped silicon oxide.

[0044] The ruthenium-containing wiring 7 preferably contains a simple substance of ruthenium, a ruthenium alloy, a ruthenium oxide, a ruthenium nitride, or a ruthenium oxynitride. The content of ruthenium in the ruthenium-containing wiring 7 is preferably 50 mass% or more, more preferably 60 mass% or more, and even more preferably 80 mass% or more, relative to the total mass (100 mass%) of the ruthenium-containing wiring, and may be 100 mass%. The ruthenium content is, for example, 50 to 90 atomic%. The ruthenium-containing wiring 7 can be formed by a known method, for example, CVD, ALD, etc. can be used.

[0045] The material constituting the underlayer 4 is not particularly limited, and examples thereof include silicon nitride (SiN), silicon carbonitride (SiCN), silicon carbide (SiC), aluminum oxide (AlO x ), aluminum nitride (AlN), and oxide doped carbon (ODC).

[0046] The insulating film 5 can be, for example, an oxide film, a low-k layer, and can be formed, for example, of SiOCH, doped silicon dioxide (with fluorine, carbon and other dopants), spin-on polymers (including organic and silicon-based polymers), porous oxides, etc.

[0047] The material constituting the barrier metal layer 6 is not particularly limited, and examples thereof include titanium nitride (TiN) and tantalum nitride (TaN). In the example of FIG. 1, the wiring board 1 having the barrier metal layer 6 is shown, but the wiring board may not have the barrier metal layer. In addition, a liner layer (not shown) may be disposed between the barrier metal layer 6 and the ruthenium-containing wiring 7. The material constituting the liner layer is not particularly limited, and examples thereof include Ru-containing materials and Cu-containing materials.

[0048] The method for manufacturing the wiring board 1 is not particularly limited, and may include, for example, a method including the steps of forming a base layer on the substrate, forming an insulating film, forming a trench in the insulating film, forming a barrier metal layer on the insulating film, forming a ruthenium-containing film so as to fill the trench, and performing a planarization process on the ruthenium-containing film. In addition, a step of forming a liner layer on the barrier metal layer may be included between the step of forming the barrier metal layer on the insulating film and the step of forming the ruthenium-containing film so as to fill the trench.

[0049] By performing a recess etching process on the ruthenium-containing wiring 7 in the wiring substrate 1 using the etching solution of this embodiment, it is possible to remove a part of the ruthenium-containing wiring and form a recess 2 (FIG. 2).

[0050] A specific method for the recess etching process includes a method of contacting the etching solution of the present embodiment with the wiring board 1. The contact method is not particularly limited, and examples thereof include a method of immersing the wiring board 1 in the etching solution of the present embodiment contained in a tank (immersion method), a method of discharging the etching solution of the present embodiment onto the wiring board 1 (single-wafer spin method), a method of piling the etching solution of the present embodiment on the wiring board 1 (pile method), a method of pouring the etching solution of the present embodiment onto the wiring board 1, or a combination thereof.

[0051] The processing time of the recess etching process can be appropriately adjusted depending on the etching method, the temperature of the etching solution, etc. The processing time (contact time between the etching solution and the wiring substrate) is not particularly limited, but examples thereof include 0.01 to 30 minutes, 0.1 to 20 minutes, 0.1 to 10 minutes, or 0.15 to 5 minutes. The temperature of the etching solution during the recess etching process is not particularly limited, but may be, for example, 15 to 75°C, 15 to 65°C, 15 to 65°C, or 15 to 50°C.

[0052] After the recess etching process, the wiring board obtained by the recess etching process may be treated with a predetermined chemical solution as necessary. In particular, when a barrier metal layer is disposed on the wiring board as in the wiring board 1, the components constituting the ruthenium-containing wiring and the components constituting the barrier metal layer may have different solubilities in the etching solution depending on their types. In such a case, it is preferable to use a chemical solution that has a higher solubility in the barrier metal layer to adjust the degree of dissolution of the ruthenium-containing wiring and the barrier metal layer. From this point of view, the chemical solution is preferably one that has a poor ability to dissolve the ruthenium-containing wiring and a high ability to dissolve the material constituting the barrier metal layer.

[0053] The chemical solution may be a solution selected from the group consisting of a mixture of ammonia water and hydrogen peroxide water (APM) and a mixture of hydrochloric acid and hydrogen peroxide water (HPM). The composition of the APM is preferably within the range of "ammonia water: hydrogen peroxide water: water = 1: 1: 500" to "ammonia water: hydrogen peroxide water: water = 1: 1: 3" (volume ratio). The composition of the HPM is preferably within the range of "hydrochloric acid: hydrogen peroxide water: water = 1: 1: 3" to "hydrochloric acid: hydrogen peroxide water: water = 1: 1: 400" (volume ratio). These preferred composition ratios are intended to mean composition ratios in the case where the ammonia water is 28 mass% ammonia water, the hydrochloric acid is 37 mass% hydrochloric acid, and the hydrogen peroxide solution is 31 mass% hydrogen peroxide solution. From the viewpoint of the ability to dissolve the barrier metal layer or the ability to remove particles, APM is preferred.

[0054] The method of treating the wiring substrate after recess etching with the chemical solution includes a method of contacting the wiring substrate after recess etching with the chemical solution. The contact method includes the same contact method as that mentioned in the recess etching treatment. The contact time between the chemical solution and the wiring substrate after recess etching is, for example, 0.1 to 10 minutes, or 0.15 to 5 minutes.

[0055] In the present processing method, the recess etching process and the treatment with the chemical solution may be performed alternately. When the processes are performed alternately, it is preferable to perform the cycle of the recess etching process and the treatment with the chemical solution 1 to 10 times each.

[0056] <Removal of ruthenium-containing film from the outer edge of the substrate> The etching solution of the present embodiment may be used to remove the ruthenium-containing film located on the outer edge of a substrate on which the ruthenium-containing film is disposed. For example, the etching solution of the present embodiment may be used to remove the ruthenium-containing film located on the outer edge of a laminate having a substrate and a ruthenium-containing film disposed on one main surface of the substrate.

[0057] The ruthenium-containing film preferably comprises elemental ruthenium, an alloy of ruthenium, an oxide of ruthenium, a nitride of ruthenium, or an oxynitride of ruthenium.

[0058] The specific method is not particularly limited, but for example, a method of supplying a chemical solution from a nozzle so that the etching solution of the present embodiment contacts only the ruthenium-containing film at the outer edge of the substrate. The contact method includes the same method as above. The preferred ranges of the contact time and the temperature of the etching solution are the same as above.

[0059] <Removal of ruthenium-containing material adhering to the back surface of the substrate> The etching solution of this embodiment may be used to remove ruthenium-containing substances adhering to the back surface of a substrate on which a ruthenium-containing film is disposed. When forming a laminate including a substrate and a ruthenium-containing film disposed on one main surface of the substrate, the ruthenium-containing film is formed by sputtering, CVD, or the like. At that time, ruthenium-containing substances may adhere to the surface (back surface) of the substrate opposite to the ruthenium-containing film side. The etching solution of this embodiment may be used to remove ruthenium-containing substances adhering to the back surface of such a laminate.

[0060] The specific method is not particularly limited, but for example, a method of discharging a chemical solution so that the etching solution of the present embodiment contacts only the back surface of the substrate can be mentioned. The contact method can be the same as above. The preferred ranges of the contact time and the temperature of the etching solution can be the same as above.

[0061] The etching solution of the present embodiment described above contains orthoperiodic acid as an oxidizing agent and has a pH adjusted to 8 or more and 10 or less with ammonia, so that a practical etching rate for ruthenium is maintained and the risk of generating ruthenium tetroxide can be reduced. Therefore, by using the etching solution of the present embodiment, microfabrication of a ruthenium-containing layer, cleaning of a ruthenium substrate, and the like can be performed safely and suitably.

[0062] In addition, when the number of particles larger than 100 nm in the etching solution of this embodiment is 20 particles / mL or less, the etching solution can be suitably used for recess etching treatment of ruthenium-containing wiring.

[0063] (Method of manufacturing etching solution) The method for producing an etching solution according to the second aspect of the present invention is characterized by comprising the steps of: mixing a solution containing orthoperiodic acid with aqueous ammonia to prepare a mixed solution, adjusting the pH of the mixed solution to 8 or more and 10 or less (hereinafter also referred to as "step (i)"), and filtering the mixed solution through a filter (hereinafter also referred to as "step (ii)"), in this order. The etching solution according to the first aspect is produced by the production method of this embodiment.

[0064] <Process (i)> Step (i) is a step of mixing a solution containing orthoperiodic acid with aqueous ammonia to prepare a mixed solution, and adjusting the pH of the mixed solution to 8 or more and 10 or less.

[0065] A solution containing orthoperiodic acid (hereinafter also referred to as "orthoperiodic acid solution") can be prepared by dissolving an appropriate amount of orthoperiodic acid in water. The concentration of orthoperiodic acid in the orthoperiodic acid solution can be higher than the concentration of orthoperiodic acid in the final etching solution.

[0066] The orthoperiodic acid solution may contain optional components in addition to orthoperiodic acid, as appropriate. Examples of optional components include those listed in the "<Other Components>" section of "(Etching Solution)" above.

[0067] Next, ammonia water is added to the orthoperiodic acid solution and mixed to prepare a mixed solution. The ammonia water to be used may be commercially available, for example, 25 to 30 mass % ammonia water.

[0068] The addition of aqueous ammonia to the orthoperiodic acid solution is carried out while measuring the pH of the mixture using a pH meter. At this time, the temperatures of the orthoperiodic acid solution and the mixture are preferably maintained at 23° C. When the pH of the mixture reaches a desired pH in the range of pH 8 to 10, the addition of aqueous ammonia is terminated.

[0069] Next, water is added to the mixture so that the concentration of orthoperiodic acid becomes a desired concentration. The concentration of orthoperiodic acid is preferably adjusted to be within the suitable concentration range described in the section "<Orthoperiodic acid>" in "(Etching solution)" above.

[0070] By this step, a mixed solution of orthoperiodic acid and aqueous ammonia having a pH of 8 to 10 can be obtained.

[0071] <Process (ii)> Step (ii) is a step of filtering the mixture through a filter.

[0072] The filter used in this step is not particularly limited, and filters generally used in the manufacture of chemicals used in semiconductor processes can be used without particular limitation. Examples of filter materials include fluororesins such as polytetrafluoroethylene (PTFE), polyamide resins such as nylon, and polyolefin resins (including high density and ultra-high molecular weight) such as polyethylene and polypropylene (PP). Among these, filters made of polyethylene, polypropylene, polytetrafluoroethylene, or nylon are preferred, polyethylene or polytetrafluoroethylene are more preferred, and polytetrafluoroethylene is particularly preferred.

[0073] The pore size of the filter is preferably 100 nm or less, more preferably 50 nm or less, even more preferably 20 nm or less, and particularly preferably 15 nm or less. By using a filter with a pore size of the upper limit or less, fine particles can also be removed. The lower limit of the pore size of the filter is not particularly limited, but can be, for example, 0.1 nm or more or 0.5 nm or more from the viewpoint of filtration efficiency.

[0074] The filter may be a combination of two or more types of filters. When two or more types of filters are used, filters made of different materials and having the same pore size may be used, filters made of the same material and having different pore sizes may be used, or filters made of different materials and having different pore sizes may be used. For example, the mixed liquid may be filtered using a first filter, and then filtered using a second filter having a smaller pore size than the first filter.

[0075] The number of times the mixed solution is filtered is not particularly limited and can be any number of times. The number of times the mixed solution is filtered can be, for example, 3 times or more, preferably 5 times or more, more preferably 10 times or more, even more preferably 15 times or more, and particularly preferably 20 times or more, 25 times or more, or 30 times or more. By setting the number of times of filtration to the lower limit or more, fine particles in the mixed solution can be further reduced. The upper limit of the number of times the mixed solution is filtered is not particularly limited, but can be, for example, 50 times or less from the viewpoint of production efficiency. When filtration is performed using a combination of two or more types of filters, the number of filtrations can be counted as one when the mixed liquid passes through the last filter in the combination of two or more types of filters (hereinafter also referred to as a "filter set").

[0076] When the filtration is performed twice or more times, it is preferable to filter the mixed liquid by circulating filtration.

[0077] This process makes it possible to reduce the number of fine particles in the mixed liquid, and to obtain a high-quality etching liquid.

[0078] According to the manufacturing method of this embodiment, a high-quality etching solution with reduced impurity particles (e.g., particles larger than 100 nm) can be obtained. The etching solution obtained by the manufacturing method of this embodiment has, for example, 20 particles / mL or less larger than 100 nm. Therefore, the etching solution obtained by the manufacturing method of this embodiment can be suitably used for recess etching of ruthenium-containing wiring arranged on a substrate.

[0079] (Method for treating object) A method for processing an object according to a third aspect of the present invention is characterized by comprising the step of etching an object containing ruthenium with the etching solution according to the first aspect.

[0080] Examples of the object to be treated that contains ruthenium include the same as those described in "<Object to be treated>" in "(Etching solution)" above, and a preferred example is a substrate having a ruthenium-containing layer. The method for forming a ruthenium-containing layer on a substrate is not particularly limited, and a known method can be used. Examples of such methods include sputtering, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), and atomic layer deposition (ALD). The raw material of the ruthenium-containing layer used when forming a ruthenium-containing layer on a substrate is also not particularly limited, and can be appropriately selected depending on the film formation method.

[0081] <Step of Etching Object> This step is a step of etching a ruthenium-containing object to be treated using the etching solution according to the first embodiment, and includes an operation of contacting the object to be treated with the etching solution. The method of etching is not particularly limited, and a known etching method can be used. Examples of such methods include, but are not limited to, a spray method, a dipping method, a puddle method, and the like. In the spray method, for example, the object to be treated is conveyed or rotated in a predetermined direction, and the etching solution according to the first aspect is sprayed into the space formed by the conveyed object to contact the etching solution with the object to be treated. If necessary, the etching solution may be sprayed while rotating the substrate using a spin coater. In the immersion method, the object to be treated is immersed in the etching solution according to the first aspect to bring the etching solution into contact with the object to be treated. In the puddle method, the etching liquid according to the first aspect is puddled on the object to be treated, and the object to be treated is brought into contact with the etching liquid. These etching methods can be appropriately selected depending on the structure, material, etc. of the object to be treated. In the case of the spray method or the puddle method, the amount of the etching liquid supplied to the object to be treated may be an amount that allows the surface of the object to be treated to be sufficiently wetted with the etching liquid.

[0082] The purpose of the etching treatment is not particularly limited, and may be fine processing of a ruthenium-containing surface of a treated object (e.g., a ruthenium-containing layer on a substrate), removal of a ruthenium-containing deposit adhering to a treated object (e.g., a substrate having a ruthenium-containing layer), or cleaning of a ruthenium-containing surface of a treated object (e.g., a ruthenium-containing layer on a substrate). When the purpose of the etching treatment is to finely process the ruthenium-containing surface of the treatment object, the treatment object is usually brought into contact with the etching solution after covering the areas that should not be etched with an etching mask. When the purpose of the etching treatment is to remove ruthenium-containing deposits adhering to the workpiece, the ruthenium-containing deposits are dissolved by contacting the workpiece with the etching liquid according to the first aspect, and the ruthenium deposits can be removed from the workpiece. When the purpose of the etching process is to clean a ruthenium-containing surface of a treatment object, the treatment surface is quickly dissolved by contacting the treatment object with the etching solution according to the first aspect, and impurities such as particles adhering to the surface of the treatment object are removed from the surface of the treatment object in a short period of time. The purpose of the etching process may be the same as that of the recess etching process described above.

[0083] The temperature at which the etching process is carried out is not particularly limited, and may be any temperature at which ruthenium dissolves in the etching solution. The temperature at which the etching process is carried out may be, for example, 20 to 60°C. In any of the spray method, the immersion method, and the puddle method, the etching rate increases by increasing the temperature of the etching solution, but the etching temperature can be appropriately selected while keeping the composition change of the etching solution small, and taking into consideration workability, safety, cost, etc.

[0084] The time for which the etching treatment is performed may be appropriately selected depending on the purpose of the etching treatment, the amount of ruthenium removed by etching (for example, the thickness of the ruthenium-containing layer, the amount of ruthenium deposits, etc.), and the etching treatment conditions.

[0085] Specific examples of the etching process include the processes listed in the "<Application>" section of "(Etching solution)" above. Note that the etching process in one aspect of this embodiment does not include CMP processing. As the etching process, a process for selectively etching the region composed of ruthenium in a substrate including a region composed of an insulating film and a region composed of ruthenium on the surface layer is preferable. In particular, a recess etching process for ruthenium-containing wiring is preferable.

[0086] <Optional process> The processing method of this embodiment may include any optional step in addition to the above steps, such as a step of rinsing the object to be processed. After the etching process of the object to be treated in the above-mentioned step, the iodine compound derived from the etching solution according to the first embodiment may adhere to the surface of the object to be treated as residual iodine. Such residual iodine may adversely affect the subsequent process. Therefore, it is preferable to perform a rinse process in order to remove the residual iodine from the surface of the object to be treated. In addition, the rinse process can also remove the residue of ruthenium-containing material that occurs on the surface of the object to be treated by the etching process.

[0087] The rinse treatment can be carried out by contacting the object to be treated with a rinse liquid. The contacting method is not particularly limited, and examples thereof include a method of immersing the object to be treated in the rinse liquid contained in a tank, a method of spraying the rinse liquid onto the surface of the object to be treated, a method of flowing the rinse liquid onto the surface of the object to be treated, or any combination of these methods.

[0088] Examples of rinsing liquids include hydrofluoric acid, hydrochloric acid, hydrogen peroxide, ammonia, tetramethylammonium hydroxide (TMAH), choline, a mixture of hydrofluoric acid and hydrogen peroxide (FPM), a mixture of sulfuric acid and hydrogen peroxide (SPM), a mixture of ammonia water and hydrogen peroxide (APM), a mixture of hydrochloric acid and hydrogen peroxide (HPM), carbon dioxide water, ozone water, hydrogen water, citric acid solution, sulfuric acid, ammonia water, isopropyl alcohol, hypochlorous acid solution, ultrapure water, nitric acid, oxalic acid solution, and acetic acid (including acetic acid solution). By carrying out the rinsing process using the above-mentioned rinsing liquid, it is possible to efficiently remove the residue of the ruthenium-containing material that is generated on the surface of the treatment target body by the etching process.

[0089] Examples of the acidic rinse liquid include an aqueous citric acid solution (preferably 0.01 to 10 mass% aqueous citric acid solution), hydrofluoric acid (preferably 0.001 to 1 mass% hydrofluoric acid), hydrochloric acid (preferably 0.001 to 1 mass% hydrochloric acid), hydrogen peroxide solution (preferably 0.05 to 6 mass% hydrogen peroxide solution, more preferably 0.3 to 4.5 mass% hydrogen peroxide solution), a mixture of hydrofluoric acid and hydrogen peroxide solution (FPM), a mixture of sulfuric acid and hydrogen peroxide solution (SPM), a mixture of hydrochloric acid and hydrogen peroxide solution (HPM), carbon dioxide solution (preferably 10 to 60 mass ppm carbon dioxide solution), and ozone water (preferably Examples of the aqueous solution include 5 to 60 ppm by mass ozone water), hydrogen water (preferably 0.5 to 20 ppm by mass hydrogen water), sulfuric acid (preferably a 1 to 10% by mass aqueous sulfuric acid solution), ammonia water (preferably a 0.05 to 6% by mass aqueous ammonia), a THAH aqueous solution (preferably a 0.05 to 5% by mass aqueous TMAH solution), a choline aqueous solution (preferably a 0.05 to 5% by mass aqueous choline solution), nitric acid (preferably a 0.001 to 1% by mass nitric acid), an oxalic acid aqueous solution (preferably a 0.01 to 10% by mass aqueous oxalic acid solution), and acetic acid (preferably a 0.01 to 10% by mass aqueous acetic acid solution or an acetic acid undiluted solution). The preferred conditions for FPM, SPM, APM, and HPM are the same as those described above. Hydrofluoric acid, nitric acid, and hydrochloric acid are abbreviated as HF, HNO 3 The term "ozone water," "carbon dioxide water," "ammonia water," "TMAH aqueous solution," "choline aqueous solution," and "hydrogen water" refer to aqueous solutions in which ozone and HCl are dissolved in water. 3 , CO 2 , N.H. 3 , methylammonium hydroxide ([(CH 3 ) 4 N] + [OH] - ), choline (trimethyl-2-hydroxyethylammonium hydroxide; [(CH 3 ) 3 N(CH 2 ) 2 OH] + [OH] - ), and H 2 In the present invention, an aqueous solution of These rinse solutions may be mixed together as long as the purpose of the rinse treatment is not impaired. The rinse solution may also contain an organic solvent.

[0090] The treatment time of the rinse treatment (contact time between the rinse liquid and the treated object) is not particularly limited, but is, for example, 5 seconds to 5 minutes. The temperature of the rinse liquid during treatment is not particularly limited, but is generally, for example, preferably 16 to 60°C, more preferably 18 to 40°C.

[0091] According to the method for treating an object to be treated of the present embodiment described above, an etching treatment is performed on the object to be treated using the etching solution according to the first aspect, which contains orthoperiodic acid as an oxidizing agent and has a pH adjusted to 8 to 10 with ammonia. The etching solution has a low risk of generating ruthenium tetroxide and has a practical etching rate for ruthenium, so that the etching treatment of ruthenium can be performed safely. Therefore, the treatment method of the present embodiment can be suitably used for microfabrication of a ruthenium-containing layer formed on a substrate, cleaning of a ruthenium substrate, etc.

[0092] (Method of manufacturing ruthenium-containing wiring) A method for producing a ruthenium-containing wiring according to a fourth aspect of the present invention is characterized by comprising a step of selectively etching the area composed of ruthenium by applying the etching solution according to the first aspect to a substrate including an area composed of an insulating film and an area composed of ruthenium on a surface layer.

[0093] The manufacturing method of this embodiment can be carried out in the same manner as the method described in "<<Recess Etching Treatment>>" in the "(Etching Solution)" section above.

[0094] (Method of manufacturing semiconductor device) The method for manufacturing a semiconductor device according to this embodiment is characterized by including a step of etching a target object containing ruthenium with the etching solution according to the first aspect.

[0095] The step of etching the ruthenium-containing object to be treated can be carried out in the same manner as described in the above "(Method of treating object to be treated)". The ruthenium-containing object to be treated is preferably a substrate having a ruthenium-containing layer. The substrate may be a substrate that is generally used in the manufacture of semiconductor devices.

[0096] <Other processes> The method for manufacturing a semiconductor device according to the present embodiment may include other steps in addition to the etching process. The other steps are not particularly limited, and include known steps carried out when manufacturing a semiconductor device. Examples of such steps include, but are not limited to, steps for forming each structure such as metal wiring, gate structure, source structure, drain structure, insulating layer, ferromagnetic layer, and non-magnetic layer (layer formation, etching other than the above etching process, chemical mechanical polishing, modification, etc.), resist film formation, exposure step, development step, heat treatment step, cleaning step, inspection step, etc. These other steps can be appropriately carried out before or after the above etching process step, as necessary.

[0097] According to the method for producing a semiconductor device of this embodiment described above, an etching treatment is performed on a processing target object using the etching solution according to the first aspect, which contains orthoperiodic acid as an oxidizing agent and has a pH adjusted to 8 to 10 with ammonia. Since this etching solution has a low risk of generating ruthenium tetroxide and has a practical etching rate for ruthenium, it is possible to safely perform microfabrication of a ruthenium-containing layer formed on a substrate and cleaning of the substrate. Therefore, the production method of this embodiment can be suitably used for producing semiconductor devices including ruthenium wiring and the like. EXAMPLES

[0098] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0099] <Preparation of etching solution (1)> (Examples 1 to 5, Comparative Examples 1 to 3) 2 g of orthoperiodic acid was dissolved in water. While measuring the pH at 23° C. with a pH meter, ammonia was added to the orthoperiodic acid solution to adjust it to each pH shown in Table 1. Then, water was added so that the total volume of the solution became 100 mL, and the etching solution of each example was prepared.

[0100] [Table 1]

[0101] <Etching of object to be treated (1)> The object to be treated was a ruthenium substrate having a ruthenium film (thickness 30 nm) formed on a 12-inch silicon substrate by the ALD method. The etching solution of each example was placed in a beaker, and the ruthenium substrate was immersed in the etching solution of each example at room temperature (23°C) to perform the etching treatment.

[0102] [Etching rate evaluation] After the etching process was performed by the method described above in "<Etching of the treated object>", the treated object was removed from the etching solution, and the sheet resistance of the substrate surface was measured. The etching rate of each example was calculated from the sheet resistance. The results are shown in Table 2 as "etching rate".

[0103] [Evaluation of ruthenium tetroxide generation] 20 mL of the etching solution of each example was placed in a bottle, and 0.01 g of ruthenium powder was added. Immediately after adding the ruthenium powder, the opening of the bottle was sealed with parafilm and left to stand at room temperature for 3 days. After that, discoloration of the parafilm was visually confirmed and evaluated according to the following evaluation criteria. The results are shown in Table 2 as "discoloration of parafilm." Discoloration of the parafilm indicates the formation of ruthenium tetroxide. Evaluation criteria ○: No discoloration of Parafilm ×: Parafilm discoloration

[0104] [Table 2]

[0105] As can be seen from Table 2, the parafilm did not discolor and no generation of ruthenium tetroxide was confirmed in Examples 1 to 5. In addition, the etching rate was maintained within a practical range. On the other hand, in Comparative Examples 1 and 2, the etching rate was high, but the Parafilm discolored and the generation of ruthenium tetroxide was confirmed. In Comparative Example 3, the generation of ruthenium tetroxide was not confirmed, but the etching rate was low and not practical. From the above, it can be confirmed that the etching solution of the example to which the present invention is applied makes it possible to etch ruthenium while reducing the risk of generating ruthenium tetroxide.

[0106] <Adjustment of etching solution (2)> (Examples 6 to 10, Comparative Examples 4 to 6) Orthoperiodic acid (2 g) was dissolved in water. While measuring the pH at 23° C. using a pH meter, ammonia was added to the orthoperiodic acid solution to adjust it to each pH shown in Table 3. Thereafter, water was added so that the total volume of the solution became 2000 mL, and the solution was passed through a polytetrafluoroethylene (PTFE) filter with a pore size of 15 nm 30 times to prepare the etching solution of each example. For each etching solution, the number of particles larger than 100 nm per mL of the etching solution was measured using a light scattering type liquid particle detector (KS-19F, manufactured by Rion Co., Ltd.). The results are shown in Table 3 as "number of particles (pieces / mL)". When the number of particles in the etching solution described in Example 6 was measured without passing it through a filter, the measured value was more than 10,000 particles larger than 100 nm per mL of the etching solution.

[0107] [Table 3]

[0108] <Etching of object to be treated (2)> The etching treatment of the object to be treated was carried out in the same manner as in <Etching treatment of object to be treated (1)>, except that the etching solutions of Examples 6 to 10 and Comparative Examples 4 to 6 were used as the etching solutions.

[0109] [Evaluation of etching rate / Evaluation of ruthenium tetroxide generation] The etching rate and the generation of ruthenium tetroxide were evaluated in the same manner as above. As a result, in Examples 6 to 10 and Comparative Examples 4 to 6, almost the same results as in Examples 1 to 5 and Comparative Examples 1 to 3 were obtained. That is, in Examples 6 to 10, the etching rate was 1 to 10 nm / min, which was maintained within a practical range. Furthermore, discoloration of the parafilm was not observed, and the generation of ruthenium tetroxide was not confirmed. On the other hand, in Comparative Examples 4 and 5, the etching rate was higher than in the Examples, but the parafilm was discolored, and the generation of ruthenium tetroxide was confirmed. Furthermore, in Comparative Example 6, the generation of ruthenium tetroxide was not confirmed, but the etching rate was low and not practical. [Explanation of symbols]

[0110] 1. Wiring board 2 Recess 3. Substrate 4 Base layer 5. Insulating film 6 Barrier metal layer 7 Ruthenium-containing wiring< / ph>

Claims

1. A method for producing a liquid crystal display comprising: 0.5 to 3 mass % orthoperiodic acid; and ammonia, The pH is 8 or more and 10 or less, No slurry or abrasives An etching solution for etching ruthenium.

2. 2. The etching solution according to claim 1, wherein the number of particles larger than 100 nm contained in the etching solution is 20 particles / mL or less.

3. The etching solution according to claim 1 or 2, wherein the etching process does not fall under a CMP process.

4. The etching solution according to any one of claims 1 to 3, wherein the etching treatment is a treatment in which the etching solution is applied to a substrate including a surface region composed of an insulating film and a surface region composed of ruthenium, thereby selectively etching the surface region composed of ruthenium.

5. A method for producing the etching solution according to any one of claims 1 to 4, comprising the steps of: a step of mixing a solution containing orthoperiodic acid with ammonia water to prepare a mixed solution, adjusting the pH of the mixed solution to 8 or more and 10 or less, and adjusting the concentration of orthoperiodic acid in the mixed solution to 0.5 to 3 mass %; filtering the mixture through a filter; in that order.

6. 5. A method for treating an object, comprising the step of etching the object containing ruthenium with the etching solution according to claim 1.

7. A method for producing a ruthenium-containing wiring, wherein the etching treatment is a treatment for selectively etching the region composed of ruthenium by applying the etching solution according to any one of claims 1 to 4 to a substrate including a region composed of an insulating film and a region composed of ruthenium on a surface layer.

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