Ruthenium semiconductor processing liquid and method for producing the same

Abstract

The present invention provides a ruthenium semiconductor treatment liquid, which contains hypobromite ions. In addition, a ruthenium semiconductor treatment liquid is provided, which is mixed with at least a bromine-containing compound, an oxidant, an alkali compound and water, wherein the amount of the bromine-containing compound added relative to the total mass is 0.01 mass% or more and less than 2 mass% in terms of the bromine element, the amount of the oxidant added is 0.1 mass% or more and 10 mass% or less, and the pH is 8 or more and 14 or less. In addition, a method for manufacturing a ruthenium semiconductor treatment liquid is provided, which includes: a step of mixing a solution containing a hypochlorous acid compound and an alkali compound with a bromine-containing compound.

Description

Technical Field

[0001] The present invention relates to a processing liquid used for etching ruthenium of a semiconductor wafer containing ruthenium in a manufacturing process of a semiconductor element. Background Art

[0002] In recent years, the design rules of semiconductor elements have been miniaturized, and there is a tendency for wiring resistance to increase. As a result of the increase in wiring resistance, the high-speed operation of semiconductor elements is significantly hindered, and countermeasures are needed. Therefore, as a wiring material, it is desired to have a wiring material with electromigration resistance and a lower resistance value than the previous wiring materials.

[0003] Compared with aluminum and copper, which are conventional wiring materials, ruthenium has a high resistance to electromigration, and has attracted attention as a wiring material for semiconductor elements whose design rules are below 10 nm, in particular, for the reason of reducing the resistance value of the wiring. In addition, ruthenium can prevent electromigration when copper is used as the wiring material, and therefore the use of ruthenium as a barrier metal for copper wiring has also been studied.

[0004] Furthermore, in the wiring forming process of semiconductor elements, when ruthenium is selected as the wiring material, the wiring is formed by dry etching or wet etching, as in the case of conventional wiring materials. However, ruthenium is difficult to remove by etching in a dry process using an etching gas or etching using CMP grinding, so more precise etching is desired, and specifically, wet etching has attracted attention.

[0005] When wet etching ruthenium, the dissolution rate of ruthenium, that is, the etching rate, is important. If the etching rate is fast, ruthenium can be dissolved in a short time, and the number of wafers processed per unit time can be increased.

[0006] In the case of wet etching of ruthenium under alkaline conditions, ruthenium, for example, in the form of RuO4 － 、RuO4 2－ Dissolved in the treatment solution in the form of RuO4 － 、RuO4 2－ In the treatment liquid, it changes to RuO4, part of which is gasified and discharged into the gas phase. RuO4 is highly oxidizing and therefore not only harmful to the human body, but is also easily reduced to produce RuO2 particles. Generally, particles lead to a decrease in yield and are therefore a very serious problem in the semiconductor formation process. In view of this background, it is very important to suppress the generation of RuO4 gas.

[0007] As a treatment liquid for etching ruthenium from such a semiconductor wafer, Patent Document 1 proposes a treatment liquid for a wafer containing ruthenium, which contains hypochlorite ions and a solvent and has a pH of more than 7 and less than 12.0 at 25° C. This liquid contains hypochlorite ions and is shown to be able to remove ruthenium and tungsten attached to the end surface and back surface of the semiconductor wafer.

[0008] Patent document 2 describes an etching composition for ruthenium-based metals, characterized in that a bromine-containing compound, an oxidizing agent, an alkaline compound and water are added and mixed, wherein the amount of the bromine-containing compound added is 2 to 25% by mass in terms of the bromine element relative to the total mass, the amount of the oxidizing agent added is 0.1 to 12% by mass, and the pH is greater than 10 and less than 12.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: International Publication No. 2019 / 142788

[0012] Patent Document 2: International Publication No. 2011 / 074601 Summary of the invention

[0013] Problems to be solved by the invention

[0014] As for etching ruthenium from a semiconductor wafer having ruthenium, it is important to take into account both the etching rate of ruthenium and the suppression of RuO4 gas. However, according to the research of the inventors, it can be understood that in the previous processing liquids recorded in the prior art documents, there is room for improvement in the following aspects.

[0015] For example, Patent Document 1 describes a treatment liquid having a pH of more than 7 and less than 12.0 as a treatment liquid for wafers containing ruthenium. In the treatment liquid described in Patent Document 1, the etching rate of ruthenium is sufficient, but there is no mention of RuO4 gas. In fact, the generation of RuO4 gas cannot be suppressed in the method described in Patent Document 1. That is, for the treatment liquid for wafers containing ruthenium described in Patent Document 1, it is difficult to take into account both the etching rate of ruthenium and the control of RuO4 gas.

[0016] The etching composition of ruthenium-based metals described in Patent Document 2 is characterized in that the pH is above 10 and less than 12. In this pH range, RuO4 gas is generated along with the etching of ruthenium, so there is room for improvement. In addition, in Patent Document 2, there is no mention of the suppression of RuO4 gas. In fact, the generation of RuO4 gas cannot be suppressed in the method described in Patent Document 2. In addition, the etching composition has the following problems: the stability of the chemical solution is poor, and the etching rate of ruthenium varies greatly over time. Moreover, as a method for preparing the treatment liquid, a method is shown in which an oxide obtained by oxidizing a bromine-containing compound under acidic conditions with an oxidant, an alkali compound is mixed with the oxide, and the pH is appropriately adjusted to alkaline. However, mixing the oxide with the alkali compound requires waiting for several hours for the generation of bromine gas, and a large amount of a high concentration of the alkali compound is required to change the pH from acidic to alkaline, etc., and there is room for improvement in the operation of the treatment liquid. Therefore, the present invention is completed in view of the above-mentioned background technology, and its purpose is to provide a processing liquid and a method for manufacturing the processing liquid, wherein the processing liquid etches ruthenium attached to the surface, end face portion and back face portion of the semiconductor chip at a sufficient speed, has excellent speed stability, and can inhibit the generation of RuO4 gas.

[0017] Solutions for solving problems

[0018] The inventors of the present invention have conducted in-depth research to solve the above problems. Then, it was found that by treating ruthenium with a treatment solution containing hypobromite ions, ruthenium can be etched at a high speed. In addition, it was found that the bromine-containing compound added to the alkaline treatment solution is oxidized by the oxidant in the treatment solution to become bromine oxide, which can etch ruthenium at a higher speed. In addition, it was found that by setting an appropriate pH range, bromine-containing compound concentration range and oxidant concentration range, it can be stabilized at a sufficient etching speed and suppress the generation of RuO4 gas, thereby completing the present invention.

[0019] That is, the configuration of the present invention is as follows.

[0020] Item 1: A ruthenium semiconductor processing liquid containing hypobromite ions.

[0021] Item 2: The semiconductor processing liquid according to Item 1, wherein the hypobromite ion is 0.001 mol / L or more and 0.20 mol / L or less.

[0022] Item 3: The semiconductor processing liquid according to Item 1 or 2, wherein the hypobromite ion is 0.01 mol / L or more and 0.10 mol / L or less.

[0023] Item 4: The semiconductor processing liquid according to any one of Items 1 to 3, wherein the semiconductor processing liquid further comprises an oxidant having a redox potential exceeding the ratio of hypobromite ion / Br － The redox potential of the system.

[0024] Item 5: The semiconductor processing liquid according to Item 4, wherein the oxidizing agent contained in the semiconductor processing liquid is hypochlorite ion or ozone.

[0025] Item 6: The semiconductor processing liquid according to any one of Items 1 to 5, further comprising tetraalkylammonium ions.

[0026] Item 7: The semiconductor processing liquid according to Item 6, wherein the tetraalkylammonium ion is a tetramethylammonium ion.

[0027] Item 8: The semiconductor processing liquid according to any one of Items 1 to 7, wherein the ratio of the hypobromite ion to 1 mol of the bromine element contained in the semiconductor processing liquid exceeds 0.5 mol.

[0028] Item 9: The semiconductor processing liquid according to any one of Items 1 to 8, wherein the pH of the processing liquid is 8 or more and 14 or less.

[0029] Item 10: The semiconductor processing liquid according to any one of Items 1 to 9, wherein the pH of the processing liquid is 12 or more and less than 13.

[0030] Item 11: A ruthenium semiconductor processing liquid, which contains at least: a bromine-containing compound, an oxidant, an alkaline compound and water, wherein the amount of the bromine-containing compound added is greater than 0.008 mass% and less than 10 mass% in terms of bromine element relative to the total mass, the amount of the oxidant added is greater than 0.1 mass ppm and less than 10 mass%, and the pH is greater than 8 and less than 14.

[0031] Item 12: The ruthenium semiconductor processing liquid according to Item 11, wherein the amount of the bromine-containing compound added is 0.08 mass % or more and less than 2.0 mass % in terms of bromine element amount.

[0032] Item 13: A ruthenium semiconductor processing liquid according to Item 11 or 12, wherein the amount of the bromine-containing compound added is greater than 0.01 mass % and less than 2 mass % in terms of the amount of bromine element, and the amount of the oxidant added is greater than 0.1 mass % and less than 10 mass %.

[0033] Item 14: The semiconductor processing liquid according to any one of Items 11 to 13, wherein the ruthenium is a ruthenium-based metal or a ruthenium alloy.

[0034] Item 15: The semiconductor processing liquid according to any one of Items 11 to 14, wherein the oxidizing agent is a hypochlorous acid compound or ozone.

[0035] Item 16: The semiconductor processing liquid according to any one of Items 11 to 15, wherein the bromine-containing compound is a bromine salt or hydrogen bromide.

[0036] Item 17: The semiconductor processing liquid according to Item 16, wherein the bromine salt is tetraalkylammonium bromide.

[0037] Item 18: The semiconductor processing liquid according to Item 17, wherein the tetraalkylammonium bromide is tetramethylammonium bromide.

[0038] Item 19: The semiconductor processing liquid according to any one of Items 11 to 18, wherein the alkaline compound is tetramethylammonium hydroxide.

[0039] Item 20: The semiconductor processing liquid according to any one of Items 11 to 19, wherein the pH is 12 or more and 14 or less.

[0040] Item 21: The semiconductor processing liquid according to any one of Items 11 to 20, wherein the pH is 12 or more and less than 13.

[0041] Item 22: The semiconductor processing liquid according to Item 14, wherein the ruthenium-based metal contains 70 atomic % or more of ruthenium.

[0042] Item 23: The semiconductor processing liquid according to Item 14, wherein the ruthenium-based metal is metallic ruthenium.

[0043] Item 24: The semiconductor processing liquid according to Item 14, wherein the ruthenium alloy contains 70 atomic % or more and 99.99 atomic % or less of ruthenium.

[0044] Item 25: The semiconductor processing liquid according to any one of Items 11 to 24, wherein the ratio of the hypobromite ion to 1 mol of the bromine element contained in the semiconductor processing liquid exceeds 0.5 mol.

[0045] Item 26: A production method, which is the production method for a semiconductor processing liquid according to any one of Items 11 to 25, comprising: a step of mixing a solution containing the oxidizing agent and the alkaline compound with the bromine-containing compound.

[0046] Item 27: A production method, which is the production method for a semiconductor processing liquid according to any one of Items 11 to 25, comprising: a step of mixing the bromine-containing compound into an aqueous solution of the oxidizing agent and the alkaline compound.

[0047] Item 28: A method for processing a substrate, comprising: manufacturing a semiconductor processing liquid by the manufacturing method described in Item 26 or 27, and then etching a ruthenium-based metal film and / or a ruthenium alloy film deposited on the substrate using the semiconductor processing liquid.

[0048] Item 29: A method for producing a ruthenium semiconductor processing liquid, comprising: a step of mixing a solution containing an alkali compound with hypobromous acid, a hypobromite, bromine water, or bromine gas.

[0049] Item 30: A method for producing a ruthenium semiconductor processing liquid, comprising: a step of mixing a solution containing a hypochlorous acid compound and an alkali compound with a bromine-containing compound.

[0050] Item 31: A method for manufacturing a semiconductor processing liquid according to Item 30, wherein the step of mixing a solution containing a hypochlorous acid compound and an alkali compound with a bromine-containing compound is a step of adding the bromine-containing compound to the solution containing the hypochlorous acid compound and the alkali compound and mixing them.

[0051] Item 32: The method for producing a semiconductor processing liquid according to any one of Items 29 to 31, wherein the solution is an aqueous solution.

[0052] Item 33: The production method according to any one of Items 29 to 32, wherein the ruthenium is a ruthenium-based metal or a ruthenium alloy.

[0053] Item 34: The method for producing a semiconductor processing liquid according to any one of Items 29 to 33, wherein the alkaline compound is tetramethylammonium hydroxide.

[0054] Item 35: The method for producing a semiconductor processing liquid according to any one of Items 30 to 34, wherein the bromine-containing compound is a bromine salt or hydrogen bromide.

[0055] Item 36: The method for producing a semiconductor processing liquid according to Item 35, wherein the bromide salt is onium bromide.

[0056] Item 37: The method for producing a semiconductor processing liquid according to Item 36, wherein the onium bromide is a quaternary onium bromide or a tertiary onium bromide.

[0057] Item 38: The method for producing a semiconductor processing liquid according to Item 37, wherein the quaternary onium bromide is tetraalkylammonium bromide.

[0058] Item 39: The method for producing a semiconductor processing liquid according to Item 38, wherein the tetraalkylammonium bromide is produced from tetraalkylammonium hydroxide and bromide ions.

[0059] Item 40: The method for producing a semiconductor processing liquid according to Item 38 or 39, wherein the tetraalkylammonium bromide is produced from tetraalkylammonium hydroxide and hydrogen bromide.

[0060] Item 41: The method for producing a semiconductor processing liquid according to Item 35, wherein the bromide salt is ammonium bromide, sodium bromide, or potassium bromide.

[0061] Item 42: The method for producing a semiconductor processing liquid according to any one of Items 30 to 41, wherein the solution containing the hypochlorous acid compound is a tetraalkylammonium hypochlorite solution.

[0062] Item 43: A method for manufacturing a semiconductor processing liquid according to Item 42, wherein the process for manufacturing the tetraalkylammonium hypochlorite solution includes: a preparation process for preparing a tetraalkylammonium hydroxide solution; and a reaction process for contacting the tetraalkylammonium hydroxide solution with chlorine, wherein the carbon dioxide concentration in the gas phase in the reaction process is less than 100 volume ppm, and the pH of the liquid phase in the reaction process is greater than 10.5.

[0063] Item 44: The method for producing a semiconductor processing liquid according to Item 43, wherein the alkyl group of the tetraalkylammonium hydroxide prepared in the preparation step has 1 to 10 carbon atoms.

[0064] Item 45: The method for producing a semiconductor processing liquid according to Item 43 or 44, wherein the reaction temperature in the reaction step is greater than or equal to -35°C and less than or equal to 25°C.

[0065] Item 46: The method for producing a semiconductor processing liquid according to any one of Items 43 to 45, wherein a carbon dioxide concentration in the tetraalkylammonium hydroxide solution in the reaction step is 0.001 ppm to 500 ppm.

[0066] Effects of the Invention

[0067] According to the present invention, ruthenium can be wet-etched stably at a sufficiently fast speed in the semiconductor forming process, and the generation of RuO4 gas can be suppressed. As a result, not only the wafer processing efficiency per unit time is improved, but also the reduction in yield caused by RuO2 particles is suppressed, and the processing can be safe for the human body, achieving a balance between manufacturing cost and safety.

[0068] Furthermore, according to the method described in the present invention, bromine, hypobromous acid, hypobromous acid ions, bromous acid, bromous acid ions, bromic acid, bromic acid ions, perbromous acid, and perbromous acid ions can be rapidly produced by directly oxidizing the bromine-containing composition in an alkaline treatment solution using an oxidant. Since the treatment solution produced in this way contains hypobromous acid ions, there is no need to wait for a long time for bromine gas to be generated, and etching of ruthenium can be performed immediately, thereby shortening the time required for semiconductor manufacturing.

[0069] Furthermore, since it is not necessary to adjust the pH of the treatment liquid from acidic to alkaline, the amount of the alkaline compound added to the treatment liquid can be greatly reduced, and the handling of the treatment liquid becomes easy. DETAILED DESCRIPTION

[0070] (Semiconductor processing fluid)

[0071] The treatment solution of the present invention is characterized by containing hypobromite ions (BrO － ) treatment liquid. Hypobromous acid ions are oxidants with strong oxidizing properties, and the treatment liquid of the present invention containing hypobromous acid ions can etch ruthenium at a high speed under alkaline conditions. Moreover, it is a treatment liquid that can suppress the generation of RuO4 gas and etch ruthenium at a stable etching rate by appropriately selecting pH, the type and concentration of the oxidant. Therefore, the treatment liquid of the present invention is a treatment liquid that can be preferably used in etching processes, residue removal processes, cleaning processes, CMP processes, etc. in semiconductor manufacturing processes. It should be noted that in this specification, a ruthenium semiconductor refers to a semiconductor containing ruthenium.

[0072] When the treatment liquid of the present invention is used, the generation of RuO4 gas can be suppressed, and ruthenium attached to the surface, end surface and back surface of the semiconductor wafer can be removed at a sufficient etching rate. The sufficient etching rate in the present invention refers to If the etching rate of ruthenium is The above can be preferably used in etching process, residue removal process, cleaning process, CMP process, etc. In addition, the amount of RuO4 gas generated when etching ruthenium depends on the processing conditions (for example, the amount of dissolved ruthenium; the volume of the treatment solution used; the processing temperature; the volume and material of the container and chamber, etc.). Therefore, when comparing the amount of RuO4 gas generated, it is important to consider these conditions. In simple terms, it can be evaluated by the amount of generation per unit area of ​​the wafer containing ruthenium. The RuO4 gas generated by etching can be captured in a suitable absorption liquid (for example, an alkaline solution such as an aqueous solution of NaOH), and the amount of ruthenium in the capture liquid is quantified, and then divided by the area of ​​the wafer used to obtain the amount of RuO4 generated per unit area of ​​the wafer containing ruthenium. Therefore, in order to confirm the RuO4 gas suppression effect, it is only necessary to compare the amount of RuO4 gas generated per unit area. The treatment liquid with a low amount of RuO4 generated per unit area can suppress the generation of RuO4 gas and suppress the generation of RuO2 particles, so it can be preferably used for etching of ruthenium.

[0073] The treatment liquid of the present invention can etch ruthenium, but does not etch metals such as copper, cobalt, titanium, platinum, titanium nitride, and tantalum nitride, or the etching rate thereof is extremely low compared to ruthenium-based metals. Therefore, in semiconductor manufacturing processes, the ruthenium-based metals can be selectively etched without damaging substrate materials containing these metals.

[0074] In the present invention, the etching rate of ruthenium is stable, which means that the etching rate of ruthenium based on the treatment solution containing hypobromite ions does not change over time. Specifically, it means that when a plurality of wafers (the number of wafers is set to n) having ruthenium are etched using the same treatment solution, the etching rate of ruthenium in the first wafer is substantially the same as the etching rate of ruthenium in the nth wafer. Here, substantially the same means that the range of variation of the etching rate of ruthenium in the nth wafer relative to the etching rate of ruthenium in the first wafer, that is, the increase or decrease of the etching rate is within ±20%. In addition, the time when the etching rate of ruthenium in the nth wafer increases or decreases within ±20% relative to the etching rate of ruthenium in the first wafer is set as the stabilization time of the etching rate. The preferred value of the stabilization time of the etching rate varies according to the conditions and manufacturing process used by the treatment solution of the present invention. For example, a treatment solution with a stabilization time of the etching rate of more than 1 hour can be preferably used in a semiconductor manufacturing process. Considering that there is a margin of time for the operation of the processing liquid and the process time can be flexibly set, a processing liquid whose etching rate is stabilized for 10 hours or more is more preferable.

[0075] A processing liquid whose etching rate of ruthenium does not change over time, or a processing liquid whose etching rate is stable for a long time, can not only stably etch ruthenium using the processing liquid in the semiconductor manufacturing process, but also reuse the processing liquid, thus becoming a processing liquid that is excellent in productivity and cost.

[0076] The hypobromite ions contained in the treatment liquid of the present invention can be generated in the treatment liquid or added to the treatment liquid in the form of hypobromite. The hypobromite mentioned here refers to a salt containing hypobromite ions or a solution containing the salt. In order to generate hypobromite ions in the treatment liquid, for example, bromine gas can be blown into the treatment liquid. In this case, from the perspective of efficiently generating hypobromite ions, the treatment liquid is preferably below 50°C. If the treatment liquid is below 50°C, not only can hypobromite ions be efficiently generated, but the generated hypobromite ions can also be stably used for etching ruthenium. Moreover, in order to dissolve more bromine in the treatment liquid, the temperature of the treatment liquid is more preferably below 30°C, and most preferably below 25°C. There is no particular restriction on the lower limit of the temperature of the treatment liquid, and it is preferred that the treatment liquid does not freeze. Therefore, the treatment liquid is preferably above -35°C, more preferably above -15°C, and most preferably above 0°C. There is no particular restriction on the pH of the treatment liquid into which the bromine gas is blown, and as long as the pH of the treatment liquid is alkaline, hypobromite ions can be immediately provided for etching of ruthenium after generation.

[0077] Furthermore, in the case where hypobromous acid ions are generated by blowing bromine gas into the treatment liquid, if the treatment liquid contains bromide ions (Br － ), the solubility of bromine gas (Br2) increases. The reason is that Br2 dissolved in the treatment liquid － Br3 － Reaction, forming Br3 － Br5 － Such complex ions are stabilized in the treatment solution. They often contain Br2, Br － Br3 － Br5 － The treatment liquid of the above type can generate more hypobromite ions and can therefore be preferably used as the treatment liquid of the present invention.

[0078] Furthermore, by oxidizing a bromine-containing compound with an oxidizing agent, hypobromite ions can be produced in the treatment liquid.

[0079] In order to add the hypobromite ion to the treatment solution in the form of a compound, it is sufficient to add hypobromous acid, bromine water, and / or a hypobromite. As the hypobromite, sodium hypobromite, potassium hypobromite, and tetraalkylammonium hypobromite are preferred. In terms of not containing metal ions that are problematic in semiconductor manufacturing, hypobromous acid or tetraalkylammonium hypobromite is further preferred.

[0080] The tetraalkylammonium hypobromite is easily obtained by passing bromine gas into a tetraalkylammonium hydroxide solution. Alternatively, it can be obtained by mixing hypobromous acid with a tetraalkylammonium hydroxide solution. Furthermore, tetraalkylammonium hypobromite can also be obtained by replacing cations contained in hypobromites such as sodium hypobromite with tetraalkylammonium ions using an ion exchange resin.

[0081] The concentration of the hypobromite ion in the treatment solution of the present invention is not particularly limited as long as it does not depart from the purpose of the present invention, and is preferably calculated as more than 0.001mol / L and less than 0.20mol / L by the amount of bromine contained in the hypobromite ion. When less than 0.001mol / L, the speed of etching ruthenium is slow, and practicality is low. On the other hand, when it exceeds 0.20mol / L, it is easy to produce the decomposition of hypobromite ion, so the etching rate of ruthenium is not easy to become stable. In order to stably carry out the etching of ruthenium at a sufficient speed, the concentration of the hypobromite ion is preferably calculated as more than 0.001mol / L and less than 0.20mol / L by the amount of bromine contained in the hypobromite ion, more preferably more than 0.005mol / L and less than 0.20mol / L, most preferably more than 0.01mol / L and less than 0.10mol / L.

[0082] In order to slow down the decrease in the etching rate of ruthenium and stabilize the etching rate, it is preferred that the ratio of hypobromite ions to 1 mol of bromine contained in the treatment solution exceeds 0.5 mol. As described above, hypobromite ions are easily converted to Br by oxidation reaction and decomposition reaction of ruthenium. － Change. － Ruthenium is not etched, so in order to perform stable ruthenium etching, it is important to reduce the Br in the processing solution to － Rapidly oxidized to hypobromite ions, chemical species with high ruthenium etching ability (hypobromite ions; BrO － When the ratio of hypobromite ions to 1 mol of bromine contained in the treatment liquid of the present invention exceeds 0.5 mol, that is, more than half of the bromine in the treatment liquid is in the form of BrO － In the presence of ruthenium, the concentration of the chemical species having ruthenium etching ability can be considered to be sufficiently high, and the etching rate of ruthenium is stabilized.

[0083] The concentration of hypobromite ion in the treatment solution can be confirmed by using a widely known method. For example, if ultraviolet-visible absorption spectrophotometry is used, it is easy to confirm the absorption caused by hypobromite ion, and the hypobromite ion concentration can be obtained according to the intensity of its absorption peak (depending on the pH of the treatment solution, hypobromite ion concentration, etc., roughly around 330nm). Moreover, the hypobromite ion concentration can also be obtained by iodine titration. In addition, the hypobromite ion concentration can also be obtained according to the redox potential (ORP) and pH of the treatment solution. From the viewpoint of non-contact and continuous measurement, it is most preferred to utilize the measurement of ultraviolet-visible absorption spectrophotometry. It should be noted that when the hypobromite ion concentration is measured by ultraviolet-visible absorption spectrophotometry, in the presence of absorption caused by other chemical species, the hypobromite ion concentration can be obtained with sufficient accuracy by performing data processing such as spectral segmentation and baseline correction, appropriate selection of references, etc.

[0084] Hypobromous acid (HBrO) and hypobromous acid ion (BrO － The acid dissociation constant (pK a ) is 8.6, so in the case of low pH, HBrO and BrO may be present depending on the pH of the treatment liquid. － Coexistence. The treatment solution contains HBrO and BrO － In the case of HBrO and BrO － The total concentration of can be used as the concentration of the hypobromous acid ion.

[0085] The details of the mechanism by which hypobromite ions dissolve ruthenium are not clear, but it is speculated that hypobromite ions or hypobromous acid generated by hypobromite ions in the treatment solution oxidize ruthenium to generate RuO4 and RuO4－ or RuO4 2－ , thereby dissolving in the treatment solution. － or RuO4 2－ In order to dissolve ruthenium in the form of RuO4, the amount of RuO4 gas generated can be reduced and the generation of RuO2 particles can be inhibited. － or RuO4 2－ The pH of the treatment liquid is preferably alkaline, more preferably the pH of the treatment liquid is 8 or more and 14 or less, further preferably the pH is 12 or more and 14 or less, and most preferably the pH is 12 or more and less than 13. If the pH of the treatment liquid is 12 or more and less than 13, ruthenium is dissolved in the form of RuO4 － or RuO4 2－ In the treatment solution, ruthenium is dissolved in the form of RuO4, thereby significantly reducing the amount of RuO4 gas generated and inhibiting the generation of RuO2 particles. On the other hand, when the pH of the treatment solution is less than 8, ruthenium is easily oxidized to RuO2 and RuO4, so there is a tendency for the amount of RuO2 particles to increase and the amount of RuO4 gas generated to increase. In addition, if the pH exceeds 14, ruthenium is not easily dissolved, and it is not easy to obtain a sufficient ruthenium etching rate, so the production efficiency in semiconductor manufacturing is reduced.

[0086] In order to adjust the pH of the treatment solution, an acid or a base can be added to the treatment solution. The acid can be any of an inorganic acid and an organic acid. If an example is given, it is a carboxylic acid such as hydrofluoric acid, hydrochloric acid, hydrobromic acid, nitric acid, acetic acid, sulfuric acid, peroxydisulfuric acid, formic acid, acetic acid, etc. In addition, a widely known acid for a treatment solution for semiconductors can also be used without any restrictions. As the base, from the perspective of not containing metal ions that become a problem in semiconductor manufacturing, an organic base is preferably used. If an example of an organic base is given, it is a tetraalkylammonium hydroxide composed of tetraalkylammonium ions and hydroxide ions. If an example of the tetraalkylammonium hydroxide is given, it can be listed as: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Among them, from the perspective of having a large number of hydroxide ions per unit weight and being able to easily obtain high-purity products, the organic base is preferably tetraalkylammonium hydroxide, and more preferably tetramethylammonium hydroxide.

[0087] The tetraalkylammonium ions contained in the treatment liquid may be one kind or a combination of two or more kinds.

[0088] The treatment liquid of the present invention preferably contains an oxidizing agent. The oxidizing agent is contained in the treatment liquid of the present invention, thereby playing a role in decomposing the hypobromous acid ions and generating bromide ions (Br － ) is oxidized again to hypobromous acid ion.

[0089] When ruthenium is oxidized, the hypobromite ion is reduced to Br －In addition, hypobromite ions are easily decomposed naturally in the treatment solution, and part of them changes into Br － Furthermore, the decomposition of hypobromite ions is accelerated by ultraviolet and visible light, and part of them is converted into Br － In addition, the hypobromite ion also decomposes due to heating, contact with acid, and contact with metal, and part of it changes to Br － Br is generated by the reduction and decomposition of hypobromite ions. － Since ruthenium is not dissolved, the etching rate of ruthenium decreases if the reduction or decomposition of hypobromite ions proceeds. The treatment solution contains an appropriate oxidant, which can convert the Br generated by the reduction or decomposition into － Oxidation to hypobromite ions can slow down the decrease in the etching rate of ruthenium. That is, the treatment solution contains hypobromite ions and an appropriate oxidant, thereby extending the stable time of the etching rate.

[0090] The oxidant optionally contained in the treatment solution is preferably an oxidant / the redox potential of the chemical species generated by the reduction of the oxidant exceeds the redox potential of the hypobromite ion / Br － If such an oxidant is used, Br － The redox potential between the oxidant and the chemical species produced by the reduction of the oxidant, which may be contained in the treatment solution, varies depending on the concentration of the oxidant and the chemical species produced by the reduction of the oxidant, the temperature and pH of the solution, but does not depend on these conditions. As long as the redox potential between the oxidant and the chemical species produced by the reduction of the oxidant exceeds the redox potential between the oxidant and the chemical species produced by the reduction of the oxidant, the redox potential between the oxidant and the chemical species produced by the reduction of the oxidant exceeds the redox potential between the oxidant and the chemical species produced by the reduction of the oxidant. － The redox potential of the system is sufficient.

[0091] On the other hand, the upper limit of the redox potential between the oxidant and the chemical species generated by the reduction of the oxidant, which may be contained in the treatment solution, is not particularly limited unless it deviates from the purpose of the present invention. － When the redox potential of the RuO4 system is high (1.0 V vs. SHE), the RuO4 dissolved in the treatment solution － Oxidized to RuO4 by the oxidant, the generation of RuO4 gas may increase. In this case, by appropriately adjusting the amount of oxidant added to the treatment solution and the timing of adding the oxidant, the generation of RuO4 gas can be suppressed. － Towards the oxidation of RuO4, the amount of RuO4 gas generated is controlled.

[0092] From the viewpoint of not containing metal elements that are problematic in semiconductor manufacturing, the oxidant optionally contained in the treatment liquid of the present invention is preferably hypochlorite ion or ozone. Among them, hypochlorite ion is more preferred because of its high solubility in the treatment liquid, its stable presence in the solution, and its easy concentration adjustment.

[0093] Hypochlorite ions and ozone have the ability to convert Br into － The ability to be reoxidized to hypobromite ion. It can be known from the following: hypochlorite ion / Cl － The redox potential of the ozone / oxygen system is 0.89 V, and the redox potential of the ozone / oxygen system is 1.24 V. In contrast, the redox potential of the hypobromite ion / Br － The oxidation-reduction potential of the system is 0.76 V. It should be noted that the above oxidation-reduction potential is a value relative to a standard hydrogen electrode at pH 14 (25° C.). Therefore, the treatment solution of the present invention containing hypobromite ions and hypochlorite ions or ozone can be used to reduce the oxidation-reduction potential of the system by Br － The ruthenium is oxidized to hypobromous ions and the concentration of hypobromous ions in the treatment solution is maintained at a high concentration, so that the etching rate of ruthenium can be stabilized.

[0094] Table 8 shows an example of using hypochlorite ion as an oxidant. It can be seen that the redox potential of hypochlorite ion / Cl － The ratio of hypobromite ion to Br － Thus, for the treatment solution of the present invention containing both hypobromite ions and hypochlorite ions, the stabilization time of the etching rate of ruthenium becomes longer, so it can be particularly preferably used. On the other hand, when using an oxidizing agent such as hydrogen peroxide which is alkaline and has a weak oxidizing power, it is impossible to convert Br － Ruthenium is efficiently oxidized to hypochlorite ions, so the etching rate of ruthenium is low.

[0095] The concentration of hypochlorite ions in the treatment liquid of the present invention is not limited unless it deviates from the gist of the present invention, but is preferably 0.1 mass % or more and 10 mass % or less. If the concentration of hypochlorite ions is less than 0.1 mass %, Br － Efficient oxidation reduces the etching rate of ruthenium. On the other hand, if the addition amount of hypochlorite ions is greater than 10 mass %, the stability of hypochlorite ions is reduced, so it is not suitable. From the viewpoint of taking into account both RuO4 gas inhibition and the etching rate of ruthenium, the concentration of the oxidant is more preferably 0.3 mass % or more and 7 mass % or less, and most preferably 0.5 mass % or more and 4 mass % or less.

[0096] On the other hand, when the ratio of hypochlorite ions to hypobromite ions is high, the reaction of hypochlorite ions with hypobromite ions to form bromate ions proceeds, so that the hypobromite ion concentration decreases.

[0097] The concentration of ozone in the treatment liquid of the present invention is not limited unless it deviates from the gist of the present invention, but is preferably 0.1 mass ppm or more and 1000 mass ppm (0.1 mass %) or less. When it is less than 0.1 mass ppm, Br－ The speed of oxidation to hypobromite ion is slow, and does not affect the etching speed of ruthenium. In addition, from the viewpoint of stably dissolving ozone in the treatment solution, the concentration of ozone is more preferably 1 mass ppm or more and 500 mass ppm or less. Moreover, if the concentration of ozone is 5 mass ppm or more and 200 mass ppm or less, Br － It is highly oxidized to hypobromite ions, and therefore is particularly preferred. In addition, the method for generating ozone and the method for dissolving it in the treatment liquid can use widely known methods without any problem. For example, it can be that ozone is generated by discharging a gas containing oxygen, and a part or all of the ozone is dissolved in the treatment liquid by bringing the gas containing the ozone into contact with the treatment liquid, thereby preparing a treatment liquid containing ozone. The contact between ozone and the treatment liquid can be carried out continuously or intermittently. By bringing ozone into contact with the treatment liquid before starting the etching of ruthenium, BrO can be prepared. － On the other hand, in the treatment solution for etching ruthenium, i.e., containing RuO4 / RuO4 － / RuO4 2－ When the treatment liquid such as ozone is brought into contact with the treatment liquid, the generation of RuO4 gas can be prevented from increasing by bringing ozone into contact with the treatment liquid in small amounts and intermittently.

[0098] The method for generating the above-mentioned hypochlorite ions is not particularly limited, and the hypochlorite ions generated by any method can be preferably used in the treatment solution of the present invention. As the method for generating hypochlorite ions, for example, adding hypochlorite, blowing chlorine gas, etc. can be preferably used. Among them, from the viewpoint of easy control of the concentration of hypochlorite ions and easy handling of the hypochlorite, the method of adding hypochlorite to the treatment solution is preferred. If such hypochlorite is given as an example, it is tetraalkylammonium hypochlorite, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, and hypochlorous acid. Among them, from the viewpoint of not containing metals that become a problem in semiconductor manufacturing, tetraalkylammonium hypochlorite or hypochlorous acid are particularly preferred, and from the viewpoint of being able to stably exist even at high concentrations, tetraalkylammonium hypochlorite is most preferred.

[0099] As the tetraalkylammonium hypochlorite, tetraalkylammonium hypochlorite containing tetraalkylammonium ions in which the number of carbon atoms per alkyl group is 1 to 20 is preferred. Specifically, tetramethylammonium hypochlorite, tetraethylammonium hypochlorite, tetrapropylammonium hypochlorite, tetrabutylammonium hypochlorite, tetrapentylammonium hypochlorite, and tetrahexylammonium hypochlorite are preferred. Tetramethylammonium hypochlorite is most preferred because it is easy to obtain a high-purity product.

[0100] The method for producing the tetramethylammonium hypochlorite is not particularly limited, and tetramethylammonium hypochlorite produced by a widely known method can be used. For example, tetramethylammonium hypochlorite produced by a method of blowing chlorine into tetramethylammonium hydroxide, a method of mixing hypochlorous acid with tetramethylammonium hydroxide, a method of replacing cations in a hypochlorite solution with tetramethylammonium using an ion exchange resin, a method of mixing a distillate of a solution containing hypochlorite with tetramethylammonium hydroxide, etc. can be preferably used.

[0101] The treatment solution of the present invention contains hypochlorite ions or ozone and Br － In the case of Br － Whether it is further oxidized to BrO by hypochlorite ions or ozone － Depends on the hypochlorite ions and Br contained in the treatment solution － The ratio of ozone to Br － The amount ratio of Br in the treatment solution － When the molar concentration of Br is higher than that of hypochlorite ion or ozone, Br － The total amount is oxidized to BrO － Therefore, the molar concentration of hypochlorite ions or ozone in the treatment solution of the present invention is preferably higher than that of Br － The molar concentration of Br is reduced by passing a gaseous oxidant such as ozone into the treatment liquid. － Oxidized to BrO － In the case of Br, it is desirable that the total number of moles of the gaseous oxidant to be ventilated is greater than the total number of moles of Br contained in the treatment liquid. － The number of moles.

[0102] As a method for producing hypobromite ions in a treatment liquid, there is a method of oxidizing a bromine-containing compound using an oxidant. The amount ratio of the bromine-containing compound contained in the treatment liquid to the oxidant is preferably determined by taking into account the stoichiometric ratio and reaction rate when the bromine-containing compound reacts with the oxidant to generate hypobromite ions, and the amount of Br contained in the treatment liquid. － The stoichiometric ratio and reaction rate when the bromine-containing compound reacts with the oxidant to produce hypobromite ions are determined. In fact, for these reactions, multiple factors are complexly affected, so it is difficult to find the appropriate quantitative ratio of the bromine-containing compound and the oxidant. However, if the ratio of the value obtained by dividing the concentration of the bromine-containing compound by the chemical equivalent (molar equivalent) of the bromine-containing compound to the value obtained by dividing the concentration of the oxidant by the chemical equivalent (molar equivalent) of the oxidant is in the range of 0.001 to 100, not only can BrO be efficiently generated from the bromine-containing compound using the oxidant, － , and can be passed through BrO － Br produced by reduction or decomposition reaction －Oxidized again to BrO － , so the etching rate of ruthenium is stabilized.

[0103] For example, when the bromine-containing compound is tetramethylammonium bromide and the oxidant is tetramethylammonium hypochlorite, the chemical equivalent (molar equivalent) of the bromine-containing compound in the reaction between these chemical species is equal to the chemical equivalent (molar equivalent) of the oxidant, so the ratio of the molar concentration of the bromine-containing compound to the concentration of the oxidant can be in the range of 0.001 to 100.

[0104] The amount ratio of hypobromite ions to hypochlorite ions contained in the treatment liquid is preferably determined by taking into account the reduction rate of hypobromite ions, more precisely, the rate at which Br is generated by the reduction reaction and / or decomposition reaction of hypobromite ions. － The rate and utilization of hypochlorite ions by Br － To BrO － In fact, for these reactions, multiple factors affect each other in a complex manner, so it is difficult to find the appropriate ratio of hypobromite ions to hypochlorite ions. However, if the ratio of the molar concentration of hypobromite ions to the molar concentration of hypochlorite ions (molar concentration of hypobromite ions / molar concentration of hypochlorite ions) is in the range of 0.001 to 100, hypochlorite ions can be used to convert BrO － Br produced by reduction or decomposition reaction － Oxidized again to BrO － , the etching rate of ruthenium is stabilized.

[0105] The pH of the semiconductor treatment liquid of ruthenium in the present invention is preferably 8 or more and 14 or less. If the pH of the treatment liquid is 8 or more and 14 or less, ruthenium can be etched efficiently, the etching rate of ruthenium is stable, and RuO4 gas generation can be expected to be reduced. The lower the pH, the faster the etching rate of ruthenium, but the lower the pH, the more RuO4 gas generation increases. Therefore, when a semiconductor wafer containing ruthenium is treated, it is extremely important to select a pH that can take into account both etching rate and RuO4 gas suppression. From this viewpoint, the pH of the semiconductor treatment liquid of ruthenium in the present invention is more preferably set to 12 or more and 14 or less, and more preferably 12 or more and less than 13. By setting the pH of the treatment liquid to 12 or more and less than 13, ruthenium can be etched at a sufficient speed, and RuO4 gas generation can be suppressed. When the pH of the treatment liquid is less than 8, there is a tendency to easily produce RuO2 particles.

[0106] The ruthenium contained in the semiconductor wafer to which the treatment solution of the present invention is applied can be formed by any method. In the film formation of ruthenium, methods widely known in the semiconductor manufacturing process can be used, such as CVD, ALD, PVD, sputtering, plating, etc. In the present invention, ruthenium refers to a ruthenium-based metal or a ruthenium alloy.

[0107] In the present invention, "ruthenium-based metals" refer to ruthenium metals containing 70 atomic % or more of ruthenium, ruthenium oxides (RuO X ), nitride (RuN), oxynitride (RuNO), etc. Here, the oxide of ruthenium is ruthenium dioxide, ruthenium trioxide (trihydrate). In addition, in the present invention, "ruthenium alloy" refers to the following alloy: containing 70 atomic % or more and 99.99 atomic % or less of ruthenium, and containing metals other than ruthenium, the concentration of the metals other than ruthenium is higher than the concentration inevitably contained. In the present invention, when there is no need to specifically distinguish between ruthenium-based metals and ruthenium alloys, they are recorded as ruthenium.

[0108] Ruthenium alloys may contain any metal other than ruthenium. Examples of metals contained in ruthenium alloys include tantalum, silicon, copper, hafnium, zirconium, aluminum, vanadium, cobalt, nickel, manganese, gold, rhodium, palladium, titanium, tungsten, molybdenum, platinum, iridium, etc. They may also contain oxides, nitrides, and silicides thereof.

[0109] These rutheniums can be intermetallic compounds, ionic compounds, and complexes. In addition, ruthenium can also be exposed on the surface of the wafer, or it can be covered by other metals, metal oxide films, insulating films, resists, etc. When covered by other materials, when ruthenium contacts with the treatment solution of the present invention and dissolves ruthenium, RuO4 gas produces an inhibitory effect. Moreover, the treatment solution of the present invention, when not actively dissolving ruthenium, that is, performing a treatment with ruthenium as the protected object, can also suppress the RuO4 gas produced by the rarely dissolved ruthenium.

[0110] For example, when the processing liquid of the present invention is used in the ruthenium wiring formation process, it is as follows. First, a substrate composed of a semiconductor (such as Si) is prepared. The prepared substrate is subjected to an oxidation treatment to form a silicon oxide film on the substrate. Then, an interlayer insulating film composed of a low dielectric constant (Low-k) film is formed to form via holes at specified intervals. After the via holes are formed, ruthenium is buried in the via holes by thermal CVD to further form a ruthenium film. The ruthenium film is etched using the processing liquid of the present invention, and the RuO4 gas generation is suppressed while being flattened. In this way, a ruthenium wiring with suppressed RuO2 particles and high reliability can be formed.

[0111] Another embodiment of the treatment liquid of the present invention is a treatment liquid containing at least a bromine-containing compound, an oxidizing agent, an alkaline compound, and water.

[0112] (Compounds containing bromine)

[0113] The bromine-containing compound used in the treatment liquid of the present invention can be any compound as long as it contains bromine atoms and is oxidized by the oxidant described later to generate bromine, hypobromous acid, hypobromous acid ion, bromic acid, bromic acid ion, perbromic acid, perbromic acid ion, and bromide ion. If an example is given, it is preferred to use at least one selected from the group consisting of bromine salts and hydrogen bromide. The hydrogen bromide mentioned here refers to hydrogen bromide gas or an aqueous solution of hydrogen bromide, i.e., hydrobromic acid. As bromine salts, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, ammonium bromide, onium bromide, etc. can be listed. Onium bromide here refers to a compound formed by onium ions and bromide ions. Onium ions are compounds of polyatomic cations made by adding excess protons (hydrogen cations) to monoatomic anions. Specifically, it is a cation such as imidazolium ion, pyrrolidinium ion, pyridinium ion, piperidinium ion, ammonium ion, phosphonium ion, fluorine ion, chloride ion, bromide ion, iodide ion, oxonium ion, sulfonium ion, selenium ion, tellurium ion, arsonium ion, stibonium ion, bismuth ion. In addition, a compound that generates hypobromous acid or hypobromous acid ion in the treatment solution can also be preferably used as a bromine-containing compound. Examples of such compounds include bromohydantoins, bromoisocyanuric acids, bromosulfamic acids, bromochloramines, etc., but are not limited to these. More specific examples of the compound include 1-bromo-3-chloro-5,5-dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin, tribromoisocyanuric acid, and the like.

[0114] The bromine-containing compound can be added to the treatment liquid in the form of hydrogen bromide or a bromine salt, or in the form of a solution containing a bromine salt, or in the form of bromine gas. From the perspective of easy operation in the semiconductor manufacturing process, the bromine-containing compound is preferably mixed with other treatment liquids in the form of a bromine salt, a solution containing a bromine salt, or hydrogen bromide. The bromine-containing compound contained in the treatment liquid may be one type, or two or more types may be used in combination.

[0115] In semiconductor manufacturing, the mixing of metal or metal ion causes a decrease in yield, and it is desirable that the bromine-containing compound does not contain metal. From the perspective of being substantially free of metal, onium bromide in bromine gas, hydrogen bromide, and bromine salts is preferably used as the bromine-containing compound of the present invention. Among them, from the perspective of being easy to obtain industrially and easy to handle, quaternary onium bromide, tertiary onium bromide, and hydrogen bromide are further preferred as the bromine-containing compound of the present invention.

[0116] Quaternary onium bromide is a bromide salt composed of ammonium ions or phosphonium ions that can stably exist in the treatment liquid. Examples of quaternary onium bromide include tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, methyltriethylammonium bromide, diethyldimethylammonium bromide, trimethylpropylammonium bromide, butyltrimethylammonium bromide, trimethylnonylammonium bromide, decyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, trimethylstearylammonium bromide, decamethonium bromide, phenyltrimethylammonium bromide, benzyltrimethylammonium bromide, dimethylpyrrolidinium bromide, dimethylpiperidinium bromide, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylpyridinium bromide. In addition, compounds obtained by adding protons to tertiary amines, secondary amines, and primary amines can also be used as bromine-containing compounds. Examples of bromine-containing compounds include methylamine hydrobromide, dimethylamine hydrobromide, ethylamine hydrobromide, diethylamine hydrobromide, triethylamine hydrobromide, 2-bromoethylamine hydrobromide, 2-bromoethyldiethylamine hydrobromide, ethylenediamine dihydrobromide, propylamine hydrobromide, butylamine hydrobromide, tert-butylamine hydrobromide, neopentylamine hydrobromide, 3-bromo-1-propylamine hydrobromide, dodecylamine hydrobromide, cyclohexylamine hydrobromide, and benzylamine hydrobromide. If an example of quaternary phosphonium bromide is listed, it is tetramethyl phosphonium bromide, tetraethyl phosphonium bromide, tetrapropyl phosphonium bromide, tetrabutyl phosphonium bromide, tetraphenyl phosphonium bromide, methyl triphenyl phosphonium bromide, phenyl trimethyl phosphonium bromide, methoxycarbonyl methyl (triphenyl) phosphonium bromide, etc. Tertiary onium bromide is a bromide salt containing sulfonium ions that can stably exist in the treatment liquid. If an example of tertiary sulfonium bromide is listed, it is trimethyl sulfonium bromide, triethyl sulfonium bromide, tripropyl sulfonium bromide, tributyl sulfonium bromide, triphenyl sulfonium bromide, (2-carboxyethyl) dimethyl sulfonium bromide, etc. Among them, from the perspective of high stability, easy industrial acquisition of high purity products, and low cost, a bromide salt containing ammonium ions, i.e., a quaternary onium bromide, is preferred.

[0117] The quaternary onium bromide is preferably a tetraalkylammonium bromide which has particularly excellent stability and can be easily synthesized.

[0118] In the tetraalkylammonium bromide, the number of carbon atoms of the alkyl group is not particularly limited, and the number of carbon atoms of the four alkyl groups may be the same or different. As such an alkylammonium bromide, a tetraalkylammonium bromide in which the number of carbon atoms of each alkyl group is 1 to 20 can be preferably used. Among them, from the viewpoint of a large number of bromine atoms per unit weight, a tetraalkylammonium bromide in which the number of carbon atoms of the alkyl group is small can be further preferably used. If an example is given, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, etc., among which tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide are preferred, and tetramethylammonium bromide is most preferred. The bromine-containing compound contained in the treatment liquid may be one or more.

[0119] The tetraalkylammonium bromide used in the present invention may be commercially available tetraalkylammonium bromide or may be produced from tetraalkylammonium ions and bromide ions. The production method of tetraalkylammonium bromide may be to mix an aqueous solution containing tetraalkylammonium hydroxide with an aqueous solution containing bromide ions or a bromine-containing gas such as hydrogen bromide that generates bromide ions when dissolved in water.

[0120] Examples of tetraalkylammonium hydroxides used for producing tetraalkylammonium bromide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. Among them, tetramethylammonium hydroxide is more preferred because it has a large number of hydroxide ions per unit weight and can easily be obtained as a high-purity product.

[0121] Examples of bromide ion sources for producing bromide ions for producing tetraalkylammonium bromide include hydrogen bromide, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, and ammonium bromide. Among them, hydrogen bromide is preferred from the viewpoint of being substantially free of metals, being easily available industrially, and being easily available in high purity.

[0122] The amount of the bromine-containing compound added is not particularly limited and can be determined by considering the etching rate of ruthenium, the stability of the treatment solution, the solubility of the bromine-containing compound, the cost, etc. The bromine-containing compound added to the treatment solution is oxidized by the oxidant described below to become a chemical species effective for etching ruthenium, specifically, bromine (Br2), hypobromous acid (HBrO), hypobromous acid ion (BrO － ), bromine acid (HBrO2), bromine ion (BrO2 － ), bromic acid (HBrO3), bromate ion (BrO3 － ), perbromic acid (HBrO4), perbromate ion (BrO4 － ), bromide ion (Br － ).

[0123] The above-mentioned chemicals effective for etching ruthenium include HBrO, BrO － 、HBrO2、BrO2 － 、HBrO3、BrO3 － The etching rate of ruthenium in the treatment solution is high, so the treatment solution preferably contains these chemicals. Among them, HBrO and BrO are contained in large quantities. － (Hereinafter, sometimes also referred to as BrO － The etching rate of ruthenium in the processing liquid of (etc.) is particularly high, so it is more preferred in terms of shortening the processing time.

[0124] Therefore, when the bromine-containing compound is oxidized by an oxidizing agent, the bromine atoms contained in the bromine-containing compound are preferably oxidized to HBrO, BrO － 、HBrO2、BrO2 － 、HBrO3、BrO3 － , wherein the oxidation to BrO is more preferred － wait.

[0125] By increasing the BrO content in the treatment solution － Specifically, by making the BrO in 1 mol of the bromine element contained in the treatment solution － A processing solution with a ratio exceeding 0.5 moles can efficiently etch ruthenium.

[0126] Among the above mentioned chemicals effective for etching ruthenium, namely Br2, HBrO, BrO － 、HBrO2、BrO2 － 、HBrO3、BrO3 － 、HBrO4、BrO4 － decomposition; by reacting with ruthenium to form Br － In the case of Br, it is preferred that the treatment liquid contain a － The oxidant is then oxidized again to an oxidant of a chemical species effective for etching ruthenium. If such an oxidant is present in the processing liquid, the concentration of the chemical species effective for etching ruthenium can be kept high, and the etching rate of ruthenium can be maintained. － When decomposition occurs by disproportionation reaction, HBrO2 or BrO2 － To produce HBrO3 or BrO3 － And Br － In addition to BrO － In addition to HBrO2, BrO2 － 、HBrO3、BrO3 － Br －In the case of the above, it is a treatment liquid that can be preferably used for etching ruthenium. In the case where the treatment liquid contains a plurality of chemical species effective for etching ruthenium, it is also preferred that the treatment liquid contains a chemical species that can etch Br － The oxidizing agent is reoxidized to a chemical species effective for etching ruthenium.

[0127] In addition, if the treatment solution contains BrO － In addition, it also contains BrO － Decomposition products (e.g., HBrO2, BrO2 － 、HBrO3、BrO3 － Br － etc.), then the BrO in the treatment solution － The concentration change slows down and the etching rate of ruthenium is more stable. Therefore, the treatment solution of the present invention may also contain one or more of the above-mentioned BrO － Decomposition products. For example, BrO － BrO3 － The processing liquid of the present invention can be preferably used for etching of ruthenium.

[0128] In order to efficiently etch ruthenium, the BrO － The ratio is preferably more than 0.5 mol.

[0129] Bromine-containing compounds or Br － The oxidation of the chemical species effective for etching ruthenium and the etching of ruthenium are both carried out in an alkaline treatment solution, thereby producing BrO2 in 1 mol of the bromine element contained in the treatment solution. － The reason is that in the alkaline treatment solution, bromine-containing compounds or Br － Directly oxidized to BrO by oxidants － wait.

[0130] If the pH of the treatment liquid is alkaline, the Br reaction using the oxidant can be repeated and continuously performed. － Oxidation of Br and etching of ruthenium. That is, the following reactions occur repeatedly: (A) Br － (B) the chemical species effective for etching ruthenium is restored to Br by etching ruthenium. － Thus, 1 mol of bromine in the treatment solution contains BrO － The ratio exceeds 0.5 mol, which can efficiently etch ruthenium.

[0131] Furthermore, when the above reactions (A) and (B) occur repeatedly and continuously, the BrO in the treatment solution －The concentration of etc. remains almost constant, so the etching rate of ruthenium is stable.

[0132] When the above (A)Br － When the oxidant is oxidized to a chemical species effective for etching ruthenium, the oxidant in the processing solution is consumed. If all the oxidant in the processing solution is used for the reaction, no bromine-containing compounds or Br will be generated on this basis. － However, in the treatment solution with many chemical species effective for etching ruthenium, BrO in 1 mol of bromine element － In such a treatment solution where the ratio exceeds 0.5 mol, ruthenium can be etched without immediately losing the ruthenium etching ability until the chemical species effective in etching ruthenium in the treatment solution disappear.

[0133] On the other hand, if the bromine-containing compound or Br － To the oxidation of chemical species effective for etching ruthenium, bromine-containing compounds or Br － Oxidized by an oxidant, bromine gas is generated. When the bromine gas is absorbed by an alkali, hypobromite and bromine salt are generated in a molar ratio of 1:1. Therefore, the BrO contained in the treatment liquid － The ratio of bromine to 1 mol of bromine contained in the treatment liquid is 0.5 mol and does not exceed 0.5. Of course, the bromine-containing compound or Br contained in the treatment liquid － If the total amount of BrO is not oxidized, the BrO contained in the treatment solution － The ratio of is less than 0.5 relative to 1 mol of the bromine element contained in the treatment liquid.

[0134] Under acidic conditions, bromine-containing compounds or Br － In the case of ruthenium etching under alkaline conditions, the time required for the generation of bromine gas and the time required for the pH adjustment of the treatment solution are required between the generation of the chemical species effective for the etching of ruthenium by the oxidant and the etching of ruthenium, so the ruthenium etching process becomes intermittent and productivity is significantly deteriorated. Therefore, the generation of the chemical species effective for the etching of ruthenium by the oxidant under acidic conditions must be performed only once before the etching of ruthenium. In this case, the above-mentioned reaction (A) (B) does not occur repeatedly and continuously, so BrO in 1 mol of the bromine element contained in the treatment solution is 0.04 mol. － The ratio is less than 0.5.

[0135] When the above-mentioned treatment solution is used to etch ruthenium, the chemical species effective for etching ruthenium are unilaterally reduced due to the reaction with ruthenium. Therefore, BrO in 1 mol of bromine contained in the treatment solution is － The ratio is further less than 0.5.

[0136] BrO in 1 mol of bromine contained in the treatment solution－ The ratio of BrO to BrO in the treatment liquid is 0.5 mol or less. － Compared with the treatment solution with a ratio of more than 0.5 mole, the stability of the ruthenium etching rate, the number of ruthenium films that can be etched, and the lifetime of the treatment solution are greatly reduced. Therefore, in order to stably and efficiently etch ruthenium, it is preferred to make the treatment solution alkaline, and the BrO in 1 mole of bromine contained in the treatment solution － The ratio is set to be greater than 0.5 mol of the treatment liquid.

[0137] As for the bromine-containing compound, relative to the total mass of the treatment solution, the addition amount of the above-mentioned bromine-containing compound is preferably 0.008 mass % or more and less than 10 mass % in terms of the bromine element. When it is less than 0.008 mass %, the etching speed of ruthenium is slow and the practicality is low. When it is more than 10 mass %, it is difficult to control the etching speed of ruthenium, and it is difficult to control as a manufacturing process. Therefore, from the perspective of high etching speed and efficient manufacturing by controlling the etching speed, the addition amount of the bromine-containing compound contained in the treatment solution of the present invention is preferably 0.008 mass % or more and less than 10 mass % in terms of the bromine element. In addition, the upper limit of the addition amount of the bromine-containing compound contained in the treatment solution of the present invention is more preferably less than 2 mass % in terms of the bromine element. If the addition amount of the bromine-containing compound is less than 2.0 mass %, it is not easy to cause chemical species effective for etching ruthenium, especially HBrO, BrO － 、HBrO2、BrO2 － The disproportionation reaction of ruthenium can suppress the concentration fluctuation of these chemical species, and the etching rate becomes more stable. Moreover, if the addition amount of the bromine-containing compound is less than 2.0 mass %, the concentration of RuO4 gas generated per unit time can be suppressed to a low level by controlling the etching rate of ruthenium, which can further reduce the generation of RuO2 particles.

[0138] In addition, the lower limit of the addition amount of the bromine-containing compound contained in the treatment solution of the present invention is preferably calculated as 0.01% by mass or more by bromine element amount. If the addition amount of the bromine-containing compound is 0.01% by mass or more, effective chemical species for etching of ruthenium can be efficiently generated, the etching rate is further increased, and ruthenium is efficiently etched at a stable etching rate. Therefore, the addition amount of the bromine-containing compound contained in the treatment solution of the present invention is further preferably calculated as 0.01% by mass or more and less than 2% by mass by bromine element amount. In addition, from the viewpoint of increasing output (throughput), improving production efficiency, the addition amount of the bromine-containing compound is further preferably calculated as 0.04% by mass or more and less than 2.0% by mass by bromine element amount. Moreover, from the viewpoint that the reoxidation of the chemical species effective for etching of ruthenium using an oxidant is easy to occur, so the etching rate becomes more stable, the addition amount of the bromine-containing compound is most preferably calculated as 0.08% by mass or more and less than 2.0% by mass by bromine element amount.

[0139] The pH of the solution containing the bromine-containing compound is not particularly limited, but is preferably 8 or more and 14 or less, and more preferably 12 or more and 13 or less. If the solution is within this pH range, the pH drop caused when the solution containing the oxidant described later and the solution containing the bromine-containing compound are mixed can be reduced, and the treatment liquid of the present invention can be stably manufactured, stored, and used. When the pH of the solution containing the bromine-containing compound is set to less than 8, when the solution containing the oxidant described later and the solution containing the bromine-containing compound are mixed, the pH and liquid volume of the solution containing the bromine-containing compound can be adjusted so that the pH of the treatment liquid after mixing becomes alkaline.

[0140] An iodine-containing compound can also be used in the same manner as the bromine-containing compound. In this case, the iodine contained in the iodine-containing compound can be oxidized by the oxidizing agent contained in the treatment solution to become a chemical species that etches ruthenium.

[0141] (Oxidant)

[0142] The oxidant used in the treatment solution of the present invention has the following functions: it can oxidize bromine-containing compounds to generate chemicals that are effective for etching ruthenium. Specifically, it can be listed as follows: nitric acid, sulfuric acid, persulfuric acid, peroxydisulfuric acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromic acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, periodic acid, their salts, and ions generated by the dissociation of their salts. Further, it can be listed as follows: hydrogen peroxide, ozone, fluorine, chlorine, bromine, iodine, permanganate, chromate, dichromate, cerium salts, etc. These oxidants can be used alone or in combination. When adding these oxidants to the treatment solution of the present invention, any appropriate properties of solid, liquid, and gas can be selected according to the properties of the oxidant used.

[0143] Among the above-mentioned oxidizing agents, from the viewpoint of being able to stably exist even in alkaline conditions, preferred are hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, periodic acid, and salts thereof, and ions generated by dissociation of their salts, ozone or hydrogen peroxide; more preferred are hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, and salts thereof, and ions generated by dissociation of their salts, ozone or hydrogen peroxide; further preferred are hypochlorite ion or ozone; and most preferred is hypochlorite ion.

[0144] If hypochlorous acid, tetraalkylammonium hypochlorite as a salt thereof, or ozone is used as the oxidant, the mixing of metals can be substantially prevented, and thus it is preferred as a treatment liquid for semiconductor manufacturing. Among them, tetraalkylammonium hypochlorite is particularly preferred from the viewpoint of being stable in an alkali and being able to efficiently oxidize the above-mentioned bromine-containing compound.

[0145] The concentration of the oxidizing agent is not particularly limited, as long as an amount is added that can oxidize the bromine-containing compound into a chemical species effective for etching ruthenium.

[0146] The amount of the above-mentioned oxidant added is preferably 0.1 mass ppm or more and 10 mass % or less. If the amount of the oxidant added is less than 0.1 mass ppm, the bromine-containing compound cannot be efficiently oxidized, and the etching rate of ruthenium is reduced. That is, in the composition without mixing the oxidant, the etching rate is low. On the other hand, if the amount of the oxidant added is greater than 10 mass %, the stability of the oxidant is reduced and therefore inappropriate. From the viewpoint of taking into account both RuO4 gas inhibition and the etching rate of ruthenium, the concentration of the oxidant is more preferably 0.1 mass % or more and 10 mass % or less, further preferably 0.3 mass % or more and 7 mass % or less, and most preferably 0.5 mass % or more and 4 mass % or less. It should be noted that when the oxidant is ozone, the above-mentioned concentration range is preferred.

[0147] The pH of the solution containing the oxidant is not particularly limited, but is preferably 8 or more and 14 or less, and more preferably 12 or more and 13 or less. If the solution is within this pH range, the pH drop caused when the solution containing the bromine-containing compound and the solution containing the oxidant are mixed can be reduced, and the treatment liquid of the present invention can be stably manufactured, stored, and used. When the pH of the solution containing the oxidant is set to less than 8, when the solution containing the bromine-containing compound and the solution containing the oxidant are mixed, the pH and liquid amount of the solution containing the oxidant can be adjusted so that the pH of the treatment liquid after mixing becomes alkaline.

[0148] <Method for producing tetraalkylammonium hypochlorite solution>

[0149] As described above, as the oxidant optionally contained in the treatment liquid of the present invention, tetraalkylammonium hypochlorite is preferred. Therefore, the following is a description of a preferred embodiment of a method for producing tetraalkylammonium hypochlorite. The method for producing the oxidant comprises: a preparation step of preparing a tetraalkylammonium hydroxide solution; and a reaction step of contacting the tetraalkylammonium hydroxide solution with chlorine.

[0150] (Preparation step of preparing tetraalkylammonium hydroxide solution)

[0151] In tetraalkylammonium hydroxide solution, carbon dioxide from atmosphere is usually included. Carbon dioxide is present in the solution in the form of carbonate ion or bicarbonate ion. Carbon dioxide concentration is not particularly limited, and is converted into carbonate ion, preferably more than 0.001ppm and less than 500ppm (mass basis), more preferably more than 0.005ppm and less than 300ppm, further preferably more than 0.01ppm and less than 100ppm. The carbon dioxide concentration contained by the tetraalkylammonium hydroxide solution is more than 0.001ppm and less than 500ppm, which can suppress the pH change of the obtained tetraalkylammonium hypochlorite solution. As a result, the storage stability of the tetraalkylammonium hypochlorite solution can be improved.

[0152] In the present embodiment, the tetraalkylammonium hydroxide solution is preferably a solution of tetraalkylammonium hydroxide having an alkyl group with 1 to 10 carbon atoms, and more preferably a solution of tetraalkylammonium hydroxide having 1 to 5 carbon atoms. Specific tetraalkylammonium hydroxides are exemplified by tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, etc. These tetraalkylammonium hydroxides may be used alone or in combination of two or more. In addition, the carbon atoms of the four alkyl groups contained in the tetraalkylammonium hydroxide may be the same or different.

[0153] (Reaction step of contacting a tetraalkylammonium hydroxide solution with chlorine)

[0154] By bringing the tetraalkylammonium hydroxide solution into contact with chlorine and reacting them, hydroxide ions of the tetraalkylammonium hydroxide are replaced with hypochlorite ions generated from chlorine, thereby generating a tetraalkylammonium hypochlorite solution.

[0155] In the present embodiment, the upper limit of the carbon dioxide concentration in the gas phase is 100 volume ppm, but if it is 0.001 to 100 volume ppm, preferably 0.01 to 80 volume ppm, the pH of the tetraalkylammonium hypochlorite solution can be sufficiently controlled to produce a tetraalkylammonium hypochlorite solution with excellent storage stability.

[0156] The pH of the liquid phase in the reaction process of the present embodiment is in the range of 10.5 or more. The upper limit is not particularly limited. If the pH in the reaction is too high, when the same pH as after the reaction is completed is stored for a long period, hypochlorite ions may decompose and the effective chlorine concentration may decrease. Therefore, the pH of the liquid phase in the reaction process is preferably less than 14, more preferably less than 13.9, and further preferably more than 11 and less than 13.8. If the pH is in the range, the decomposition of hypochlorite ions is suppressed during the storage of the obtained tetraalkylammonium hypochlorite solution, and the storage stability is improved.

[0157] The reaction temperature of the tetraalkylammonium hydroxide solution in the reaction step of the present embodiment is preferably in the range of -35°C to 25°C, more preferably -15°C to 25°C, and even more preferably 0°C to 25°C. When the reaction temperature is in the above range, the tetraalkylammonium hydroxide solution reacts sufficiently with chlorine, and a tetraalkylammonium hypochlorite solution can be obtained with high generation efficiency.

[0158] This shows that the tetraalkylammonium hypochlorite solution obtained by the production method of the present embodiment has excellent storage stability and can be preferably used as an oxidizing agent contained in the treatment liquid of the present invention.

[0159] (Alkali Compound)

[0160] There is no particular limitation on the alkaline compound used in the treatment solution of the present invention, and lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, ammonia, choline, alkylammonium hydroxide, etc. can be used. Among these alkaline compounds, sodium hydroxide, potassium hydroxide, ammonia, choline, and alkylammonium hydroxide are easy to obtain, and when used in the treatment solution, a high ruthenium etching rate can be obtained, so they are preferred. Ammonia, choline, and alkylammonium hydroxide do not contain metals, so they can be particularly preferably used as the treatment solution of the present invention. As alkylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. can be obtained industrially, and tetramethylammonium hydroxide is most preferred in terms of being able to easily obtain high-purity grades for semiconductor manufacturing. The above-mentioned alkaline compounds can be added to the treatment solution in the form of a solid or an aqueous solution.

[0161] The concentration of the alkali compound is not particularly limited unless it deviates from the purpose of the present invention, and the pH of the solution containing the alkali compound is preferably in the range of pH 8 to pH 14, and more preferably in the range of pH 12 to pH 13. If the pH of the solution containing the alkali compound is within this pH range, the pH drop caused when the solution containing the oxidant and the solution containing the bromine-containing compound are mixed can be reduced, and the treatment solution of the present invention can be stably produced, stored, and used.

[0162] (water)

[0163] The water contained in the treatment liquid of the present invention is preferably water from which metal ions, organic impurities, particulate particles, etc. have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and pure water and ultrapure water are particularly preferred. Such water can be obtained by a well-known method widely used in semiconductor manufacturing.

[0164] (pH)

[0165] The pH of the treatment solution of the present invention is preferably above 8 and below 14. If the pH of the treatment solution is within this range, ruthenium can be etched at a sufficient speed and the generation of RuO4 gas can be suppressed. When the pH of the treatment solution is lower than 8, the generation of RuO2 particles becomes significant, and the yield of semiconductor elements deteriorates. On the other hand, when the pH of the treatment solution exceeds 14, the above-mentioned oxidant decomposes, so the oxidation of the bromine-containing compound may not be constant. This means that the etching rate of ruthenium is not constant, which will complicate the process control in the semiconductor manufacturing process and therefore needs to be avoided.

[0166] The higher the pH of the treatment solution, the less RuO4 gas is generated accompanying the etching of ruthenium. On the other hand, the higher the pH of the treatment solution, the lower the etching rate of ruthenium. Therefore, from the viewpoint of achieving both RuO4 gas suppression and etching rate, the pH of the treatment solution is preferably above 12 and below 14, and more preferably above 12 and below 13. If the pH of the treatment solution is within the above range, the chemical species effective for etching ruthenium contained in the treatment solution of the present invention can dissolve ruthenium at a sufficient etching rate and suppress the generation of RuO4 gas.

[0167] The pH when etching ruthenium metal is preferably 11 or more and 14 or less, and more preferably 12 or more and less than 13. When the pH of the treatment liquid is within this range, the etching rate and the amount of RuO4 gas generated can be reduced during the etching of ruthenium metal.

[0168] The pH when etching the ruthenium alloy is preferably 12 or more and 14 or less, and more preferably 12 or more and less than 13.

[0169] (Method for producing treatment liquid)

[0170] In the case where the treatment liquid of the present invention contains a bromine-containing compound, an oxidant, an alkaline compound and water, the treatment liquid can be a single liquid or a solution of two or more liquids. In the case where the treatment liquid is a single liquid, it becomes a solution containing all bromine-containing compounds, oxidants, alkaline compounds and water. In the case where the treatment liquid is a two or more liquid, the treatment liquid can be manufactured by mixing the liquids. In addition, in the case where the treatment liquid is a two or more liquid, each liquid contains at least one of a bromine-containing compound, an oxidant, an alkaline compound and water. It may also further contain other components described later. Even in the case where the treatment liquid is a single liquid or two or more liquids, by simultaneously having bromine-containing compounds, oxidants and alkaline compounds in the treatment liquid, the bromine-containing compound is oxidized by the oxidant to produce chemical species effective for etching ruthenium.

[0171] When the treatment liquid is set to multiple types, it is preferred to separate the treatment liquid containing the bromine-containing compound from the treatment liquid containing the oxidant. By separating the bromine-containing compound and the oxidant, oxidation of the bromine-containing compound caused by the oxidant can be prevented, and the treatment liquid of the present invention can be stably stored.

[0172] The method for mixing the processing liquid can use a method widely known as a method for mixing semiconductor liquids. For example, the following methods can be preferably used: a method using a mixing tank, a method of mixing in the piping of a semiconductor manufacturing device (inline mixing), a method of mixing by pouring a plurality of liquids simultaneously on a wafer, etc.

[0173] In the case where a plurality of treatment solutions are mixed to manufacture the treatment solution, the mixing of the treatment solution can be carried out at any time. In the case where the oxidation of the bromine-containing compound requires time, by mixing the treatment solution before etching ruthenium, the time for producing the chemical species effective for etching ruthenium can be set. In this case, if the oxidation of the bromine-containing compound requires time, it becomes a bottleneck in the manufacturing line, and therefore sometimes leads to a reduction in output. For such reasons, it is better that the time required for oxidation is short, preferably less than 1 hour. The time required for the oxidation of the bromine-containing compound can be controlled by appropriately selecting the concentration of the oxidant, the concentration of the bromine-containing compound, the pH of the treatment solution, the temperature of the treatment solution, the stirring method of the treatment solution, etc. For example, in the case where the bromine-containing compound is oxidized by using an oxidant to generate hypobromite ions, from the viewpoint of the reaction rate theory, by increasing the concentration of the reactant, the time required for oxidation can be shortened. In this case, the concentrations of both the oxidant and the bromine-containing compound can be increased, or the concentration of only one of them can be increased. In addition, by increasing the temperature of the treatment solution during mixing, the time required for the oxidation of the bromine-containing compound can also be shortened.

[0174] In addition, when the concentration of the chemical species effective for etching ruthenium is low, it is considered that the service life of the processing liquid is short and the control of the manufacturing process becomes difficult. In such a case, it is preferred to mix just before performing ruthenium etching.

[0175] Therefore, when a plurality of treatment solutions are mixed, it is preferred to mix a solution containing an oxidant and an alkali compound with a solution containing a bromine-containing compound, and it is further preferred to mix a solution containing hypochlorite ions and an alkali compound with a solution containing a bromine-containing compound. The solution containing the above-mentioned hypochlorite ions and alkali compounds is preferably alkaline. In addition, the mixing preferably adds a bromine-containing compound to the solution containing the oxidant and the alkali compound. The reason is that, for example, when the oxidant is an alkaline solution containing hypochlorous acid and the solution containing the bromine-containing compound is an acidic solution, if the former is slowly added to the latter, hypochlorous acid decomposes in the acidic solution, thereby generating toxic chlorine gas. The solution containing the oxidant and the alkali compound and the solution containing the bromine-containing compound can be both solutions or both aqueous solutions, but when the solvent such as an organic or inorganic solvent is other than water, the solvent may react with the oxidant and the oxidant decomposes. For such reasons, the solution is preferably an aqueous solution.

[0176] In the mixing of the treatment solution of the present invention, the pH of the treatment solution after mixing is preferably alkaline. Specifically, the pH of the treatment solution is preferably above 8 and below 14. In the case where the treatment solution before mixing is lower than pH 8, the concentration of the alkaline compound and / or water is adjusted in such a way that the treatment solution after mixing (comprising a bromine-containing compound, an oxidant, an alkaline compound and water) becomes pH 8 or above and below 14. In this way, by maintaining the pH of the treatment solution after mixing at above 8 and below 14, the bromine-containing compound can be rapidly changed to a chemical species effective for etching ruthenium by the oxidant, and the etching of the ruthenium film is performed at a stable and sufficient speed.

[0177] When a plurality of treatment solutions are mixed to generate a chemical species effective for etching of ruthenium, the pH of the mixed treatment solutions may be the same or different. When the pH of the treatment solutions is the same, the pH of the mixed treatment solutions does not change significantly and can be preferably used as an etching solution for ruthenium.

[0178] In the case of mixing a plurality of treatment solutions to generate chemical species effective for etching ruthenium, as long as the composition after mixing (bromine-containing compound concentration, oxidant concentration, alkaline compound concentration, pH) is within the above range, there is no particular limitation on the mixing method such as the mixing ratio and mixing order of the treatment solutions. However, for example, when an alkaline solution containing a hypochlorous acid compound is mixed with an acidic solution containing a bromine-containing compound, the decomposition of the hypochlorous acid compound may be locally carried out, so in this case, it is preferred to mix the acidic solution containing a bromine-containing compound into the alkaline solution containing a hypochlorous acid compound.

[0179] In the present invention, the hypochlorous acid compound refers to a compound that generates hypochlorous acid or hypochlorite ions in the treatment liquid. If an example of the hypochlorous acid compound is listed, it can be listed as: hypochlorous acid, hypochlorites, hydantoins, isocyanuric acids, aminosulfonic acids, chloramines, etc. Among them, hypochlorous acid and hypochlorites are preferred from the viewpoint of being able to efficiently generate hypochlorous acid or hypochlorite ions. As the hypochlorous acid, tetraalkylammonium hypochlorite is preferred, and tetramethylammonium hypochlorite is more preferred from the viewpoint of having a large amount of hypochlorous acid or hypochlorite ions per unit weight.

[0180] Chemical species effective for etching ruthenium are produced by oxidation of bromine-containing compounds by oxidants. The species vary depending on the pH of the treatment solution, oxidation-reduction potential (ORP), etc., but are mainly bromine or bromide ions, hypobromous acid, bromine acid, bromic acid, perbromic acid and their ions.

[0181] In the treatment liquid of the present invention, it is preferred that the content of metals, specifically sodium, potassium, aluminum, magnesium, iron, nickel, copper, silver, cadmium, and lead, is 1 ppb or less.

[0182] The treatment liquid of the present invention, and the bromine-containing compounds, oxidants, alkaline compounds, water, solvents, and other additives used in the treatment liquid preferably contain less ammonia and amines. The reason is that if ammonia and amines are present in the treatment liquid, they react with oxidants, bromine-containing compounds, and chemicals produced by bromine-containing compounds that are effective for etching ruthenium, which will reduce the stability of the treatment liquid. For example, when tetramethylammonium hydroxide is used in the alkaline compound, the ammonia and amines contained in the alkaline compound, especially trimethylamine, sometimes become the cause of reduced stability of the treatment liquid. Therefore, when tetramethylammonium hydroxide is used in the treatment liquid of the present invention, the total amount of amines contained in the alkaline compound is preferably less than 100 ppm. If the total amount of amines is less than 100 ppm, the effect caused by the reaction with oxidants, bromine-containing compounds, and chemicals produced by bromine-containing compounds that are effective for etching ruthenium is slight, and the stability of the treatment liquid is not impaired.

[0183] When manufacturing the processing liquid of the present invention, it is preferable to shield the liquid from light in order to prevent decomposition of oxidants caused by light, chemical species effective for etching ruthenium generated by bromine-containing compounds, and the like.

[0184] In addition, in the manufacture of the treatment solution of the present invention, it is preferred to prevent the dissolution of carbon dioxide in the treatment solution. When the treatment solution of the present invention is alkaline, carbon dioxide is easily dissolved in the treatment solution, which may cause pH changes. If the pH of the treatment solution changes, it not only becomes the cause of the etching rate variation of ruthenium, but also the stability of the treatment solution is reduced. The dissolution of carbon dioxide in the treatment solution can be reduced by the following method: an inert gas is flowed in and the carbon dioxide in the manufacturing device is purged, reacted under an inert gas atmosphere, etc. If the carbon dioxide in the manufacturing device is less than 100ppm, the influence caused by the dissolution of carbon dioxide can be ignored.

[0185] In the manufacture of the treatment liquid of the present invention, the surface in contact with the treatment liquid of the reaction container is preferably formed of glass or an organic polymer material. The reason is that if the inner surface of the reaction container is formed of glass or an organic polymer material, the impurities such as metals, metal oxides, and organic substances can be further reduced. As the organic polymer material used for the inner surface of the reaction container, vinyl chloride resins (soft / hard vinyl chloride resins), nylon resins, silicone resins, polyolefin resins (polyethylene, polypropylene), fluorine resins, etc. can be used. Among them, if the ease of molding, solvent resistance, and less dissolution of impurities are considered, fluorine resins are preferred. As the fluorine resin, there is no particular restriction as long as it is a resin (polymer) containing fluorine atoms, and known fluorine resins can be used. For example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, chlorotrifluoroethylene-ethylene copolymer, and cyclized polymers of perfluoro (butylene vinyl ether) can be listed.

[0186] (Other additives)

[0187] The treatment liquid of the present invention may be mixed with other additives used in semiconductor treatment liquids as desired within the scope of not impairing the purpose of the present invention. For example, other additives may include: acid, metal corrosion inhibitor, water-soluble organic solvent, fluorine compound, oxidant, reducing agent, complexing agent, chelating agent, surfactant, defoaming agent, pH adjuster, stabilizer, etc. These additives may be added alone or in combination.

[0188] Derived from these additives, in addition, according to the manufacturing conditions of the treatment solution, alkali metal ions, alkaline earth metal ions, etc. may also be included in the treatment solution of the present invention. For example, sodium ions, potassium ions, calcium ions, etc. may also be included. However, in the case where these alkali metal ions and alkaline earth metal ions, etc. remain on the semiconductor wafer, adverse effects (adverse effects such as reduced yield of semiconductor wafers) may be caused on the semiconductor element, so it is preferred that the amount of these alkali metal ions and alkaline earth metal ions is small, and it is actually infinitely close to not including them. Therefore, for example, as a pH adjuster, alkali metal hydroxides such as sodium hydroxide and alkaline earth metal hydroxides are not preferred, and organic bases such as ammonia, amines, choline or tetraalkylammonium hydroxides are preferred.

[0189] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1 mass % or less, more preferably 0.7 mass % or less, further preferably 0.3 mass % or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0190] The treatment liquid of the present invention may further include an organic solvent. The treatment liquid of the present invention including an organic solvent can suppress the generation of RuO4 gas. Any organic solvent may be used as long as the organic solvent does not damage the function of the treatment liquid of the present invention. If an example is given, it is cyclopentane, acetonitrile, carbon tetrachloride, 1,4-dioxane, etc., and it is natural that the organic solvent is not limited to these.

[0191] The temperature when etching ruthenium using the treatment solution of the present invention is not particularly limited, and can be determined by considering the etching rate of ruthenium, the stability of the treatment solution, the amount of RuO4 gas generated, etc. The higher the treatment temperature, the more RuO4 gas is generated, so it is preferred that the treatment temperature is low. On the other hand, the higher the temperature, the greater the etching rate of ruthenium. From the viewpoint of taking into account both RuO4 gas suppression and the etching rate of ruthenium, the temperature for etching ruthenium is preferably 10°C to 90°C, more preferably 15°C to 70°C, and most preferably 20°C to 60°C.

[0192] The treatment time when the treatment solution of the present invention is used to etch ruthenium is 0.1 to 120 minutes, preferably in the range of 0.3 to 60 minutes, which can be appropriately selected according to the etching conditions and the semiconductor element used. As a rinse solution after using the treatment solution of the present invention, an organic solvent such as alcohol can be used, but it is also sufficient to rinse with deionized water alone.

[0193] If the processing liquid of the present invention is used, the generation of RuO4 gas can be suppressed and the etching rate ( The above) removes ruthenium attached to the end surface and back surface of the semiconductor wafer. In the case of the above etching rates, the following conditions may be appropriately selected: the hypobromite ion concentration contained in the treatment liquid, the hypochlorite ion concentration, the bromine-containing compound concentration, the oxidant concentration, the pH of the treatment liquid, the treatment temperature, the contact method between the treatment liquid and the wafer, etc.

[0194] After the processing liquid of the present invention is produced, the ruthenium-based metal film and / or ruthenium alloy film deposited on the substrate can be etched using the processing liquid.

[0195] (Storage of treatment fluid)

[0196] The treatment solution of the present invention is preferably stored at low temperature and / or in a light-shielded state. By storing at low temperature and / or in a light-shielded state, the effect of inhibiting the decomposition of oxidants, hypobromite ions, etc. in the treatment solution can be expected. Moreover, by using a container sealed with an inert gas to store the treatment solution, the mixing of carbon dioxide can be prevented, and the stability of the treatment solution can be maintained. In addition, the inner surface of the container, that is, the surface in contact with the treatment solution is preferably formed by glass or an organic polymer material. The reason is that if the inner surface of the reaction vessel is formed by glass or an organic polymer material, the mixing of impurities such as metals, metal oxides, and organic matter can be further reduced. As an organic polymer material for the inner surface of the reaction vessel, the material exemplified in the manufacture of the treatment solution of the present invention can be preferably used. In addition, the pH when the treatment solution is stored can be appropriately selected, but in order to prevent the decomposition of hypobromite ions, bromine-containing compounds, oxidants, other additives, etc., the pH of the treatment solution is preferably alkaline, more preferably 8 or more and 14 or less, and most preferably 12 or more and 14 or less.

[0197] [Example]

[0198] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0199] (pH measurement method)

[0200] The pH of 10 mL of the treatment liquid prepared in Examples and Comparative Examples was measured using a tabletop pH meter (LAQUA F-73, manufactured by Horiba, Ltd.) The pH measurement was performed after the treatment liquid was prepared and stabilized at 25°C.

[0201] (Ruthenium film formation and film thickness change)

[0202] The ruthenium films used in the examples and comparative examples were formed as follows. An oxide film was formed on a silicon wafer using a batch thermal oxidation furnace, and ruthenium was formed into a film on the oxide film using a sputtering method. The sheet resistance was measured by a four-probe resistance measuring instrument (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted into film thickness, which was used as the ruthenium film thickness before etching. After etching, the sheet resistance was also measured by a four-probe resistance measuring instrument and converted into film thickness, which was used as the ruthenium film thickness after etching. The difference between the ruthenium film thickness after etching and the ruthenium film thickness before etching was used as the film thickness change before and after etching.

[0203] (Ruthenium dioxide film formation and film thickness change)

[0204] The ruthenium dioxide film used in the examples was formed as follows. An oxide film was formed on a silicon wafer using a batch thermal oxidation furnace, and a ruthenium dioxide film was formed on the oxide film using a sputtering method. The sheet resistance is measured by a four-probe resistance measuring instrument (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted into film thickness, which is the ruthenium dioxide film thickness before etching. After etching, the sheet resistance is also measured by a four-probe resistance measuring instrument and converted into film thickness, which is the ruthenium dioxide film thickness after etching. The difference between the ruthenium dioxide film thickness after etching and the ruthenium dioxide film thickness before etching is used as the film thickness change before and after etching.

[0205] (Calculation method of etching rate of ruthenium or ruthenium dioxide)

[0206] 60 mL of the treatment solution of Examples and Comparative Examples was prepared in a fluororesin container with a lid (AsOne, PFA container 94.0 mL), and each sample piece of 10×20 mm was immersed in the treatment solution at 25° C. for 1 minute to perform etching treatment of ruthenium or ruthenium dioxide.

[0207] In addition, 60 mL of the treatment solution was prepared in a fluororesin container with a lid, and immersed in a water bath heated to 60° C. (manufactured by ThermoFisher Scientific, Isotemp universal covered water bath) for 1 hour, and the temperature of the treatment solution was set to 60° C. Each sample piece having a size of 10×20 mm was immersed in the treatment solution at 60° C. for 1 minute to perform an etching treatment of ruthenium or ruthenium dioxide.

[0208] The value obtained by dividing the film thickness change before and after the etching treatment by the immersion time was calculated as the etching rate, and was evaluated as the etching rate in the present invention. The treatment temperature and treatment time are shown in Table 5. In addition, when the film thickness change before and after the treatment is less than 5 angstroms, it is considered as not etched.

[0209] (Quantitative analysis of RuO4 gas)

[0210] The amount of RuO4 gas generated was measured using ICP-OES. 5 mL of the treatment solution was taken into a sealed container and the film was formed at 25°C or 60°C with a film thickness of A 10×20 mm Si wafer containing ruthenium is immersed in it until the ruthenium is completely dissolved. Then, air (Air) is made to flow in the sealed container, and the gas phase in the sealed container is bubbled in a container with an absorption liquid (1 mol / L NaOH) added, so that the RuO4 gas generated during the immersion is captured in the absorption liquid. The amount of ruthenium in the absorption liquid is measured by ICP-OES to find the amount of Ru in the generated RuO4 gas. The complete dissolution of ruthenium on the Si wafer immersed in the treatment liquid is confirmed as follows: the sheet resistance before and after the immersion is measured by a four-probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and converted into film thickness. The amount of RuO4 gas generated is evaluated using the value obtained by dividing the weight of Ru contained in the RuO4 gas absorption liquid by the area of ​​the Ru-bearing wafer. The amount of RuO4 gas generated is 40μg / cm 2 The following cases are as follows: RuO4 gas generation is suppressed.

[0211] The compositions of the treatment liquids are shown in Tables 1 to 4, the evaluation results are shown in Table 5, the preparation conditions of the treatment liquids are shown in Table 6, the production conditions of the oxidizing agent are shown in Table 7, and the hypochlorite ion (ClO － ) / Cl － System and hypobromite ion (BrO － ) / Br － The oxidation-reduction potential (calculated value) of the system is shown in Table 8, and the preparation conditions of the tetramethylammonium bromide aqueous solution are shown in Table 9.

[0212] (Calculation method of hypobromite ion and hypochlorite ion concentration)

[0213] The concentrations of hypobromite ions and hypochlorite ions were measured using an ultraviolet-visible spectrophotometer (UV-2600, manufactured by Shimadzu Corporation). A calibration curve was prepared using hypobromite ions and hypochlorite ion aqueous solutions with known concentrations, and the concentrations of hypobromite ions and hypochlorite ions in the produced treatment solution were determined. The hypobromite ion concentration was determined based on the measured data when the absorption spectrum was stabilized after mixing a bromine-containing compound, an oxidant, and an alkali compound.

[0214] <Example 1>

[0215] (Preparation of Samples to be Etched)

[0216] A ruthenium film was formed by the method described in (Film formation of ruthenium and amount of change in film thickness), and the sample piece cut into 10×20 mm was used for evaluation.

[0217] (Manufacture of oxidants)

[0218] In a 2L glass three-necked flask (manufactured by COSMOSVID), 209g of a 25% by mass tetramethylammonium hydroxide aqueous solution and 791g of ultrapure water were mixed to obtain a 5.2% by mass tetramethylammonium hydroxide aqueous solution having a CO2 content of 0.5ppm. The pH at this time was 13.8.

[0219] Next, a rotor (AsOne, total length 30 mm x diameter 8 mm) was placed in the three-necked flask, a thermometer protection tube (COSMOSVID, bottom seal type) and a thermometer were placed in one opening, a chlorine gas tank (bombe) and a nitrogen gas tank were connected to the other opening, and the top of a PFA tube (F-8011-02, FLON Industries, Ltd.) that could switch between chlorine and nitrogen gas was immersed in the bottom of the solution, and the remaining opening was connected to a gas cleaning bottle (AsOne, gas cleaning bottle, model 2450 / 500) filled with 5 mass % sodium hydroxide aqueous solution. Next, a pressure of 0.289 Pa·m was added from the PFA tube. 3 / sec (at 0°C) for 20 minutes to discharge carbon dioxide from the gas phase. At this time, the carbon dioxide concentration in the gas phase was 1 ppm or less.

[0220] Then, a magnetic stirrer (AsOne, C-MAG HS10) was placed at the bottom of the three-necked flask and the flask was rotated and stirred at 300 rpm. The outer periphery of the three-necked flask was cooled with ice water and the pressure was maintained at 0.059 Pa·m 3 / sec (at 0°C conversion), chlorine gas (manufactured by Fujiox, purity 99.4%) was supplied for 180 minutes to obtain a mixed solution of an aqueous solution of tetramethylammonium hypochlorite (oxidant; equivalent to 3.51% by mass, 0.28 mol / L) and tetramethylammonium hydroxide (equivalent to 0.09% by mass, 0.0097 mol / L). At this time, the liquid temperature during the reaction was 11°C.

[0221] (Manufacturing of treatment liquid)

[0222] To 99.21 g of the mixed solution of the tetramethylammonium hypochlorite aqueous solution and tetramethylammonium hydroxide obtained by the above operation, 0.79 g (equivalent to 0.77% by mass, 0.05 mol / L, 0.40% by mass in terms of bromine element) of 97% by mass tetramethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to obtain 100 g of a treatment liquid having the composition described in Tables 1 to 4. Here, the water described in Table 3 refers to water containing tetramethylammonium chloride when the oxidant is tetramethylammonium hypochlorite.

[0223] (evaluate)

[0224] The pH of the treatment liquid just after manufacture, the etching rate of ruthenium, the amount of RuO4 gas produced, and the hypobromite ion concentration were evaluated. The evaluation of the etching rate of ruthenium was performed by the above-mentioned "calculation method of the etching rate of ruthenium". The evaluation of the amount of RuO4 gas produced was performed by the above-mentioned "quantitative analysis of RuO4 gas". The evaluation of the hypobromite ion concentration was performed by the above-mentioned "calculation method of hypobromite ion concentration". The stability evaluation of the etching rate was performed as described below. The etching rate of the manufactured treatment liquid was evaluated every 10 hours by the above-mentioned "calculation method of the etching rate of ruthenium". The time during which the obtained etching rate increased or decreased within ±20% relative to the etching rate just after manufacture was taken as the stabilization time of the etching rate.

[0225] <Examples 2 to 23, Comparative Examples 1 to 3>

[0226] In Examples 2 to 23 and Comparative Examples 1 to 3, the treatment liquid was prepared by the same method as in Example 1 in such a manner that the concentration of the bromine-containing compound, the concentration of the oxidant, the concentration of the alkaline compound, and the pH were the compositions shown in Tables 1 to 4, and the ruthenium film (sample sheet) prepared in the same manner as in Example 1 was used for evaluation. It should be noted that the change in film thickness before and after the treatment of Comparative Examples 1 and 2 was less than 5 angstroms, so it was judged that Ru was not etched. Therefore, the evaluation of RuO4 gas was not performed. In Examples 19 and 22, hydrobromic acid (acidic) was used as a bromine-containing compound, and after adjusting the aqueous solution (alkaline) containing hypobromite ions by mixing with an aqueous solution (alkaline) containing an oxidant and an alkaline compound, etching of ruthenium was performed. As in the other examples, it was confirmed that the etching rate of ruthenium was large, the stability of the etching rate was excellent, and the RuO4 gas inhibition effect was high.

[0227] <Example 24>

[0228] (Preparation of a solution containing an oxidizing agent and an alkali compound)

[0229] By the method for producing an oxidizing agent described in Example 1, a solution containing an oxidizing agent and an alkali compound (liquid A) was prepared so that the oxidizing agent concentration, the alkali compound concentration, and the pH had the compositions shown in Table 6.

[0230] (Preparation of a solution containing a bromine-containing compound)

[0231] 3.97 g (equivalent to 3.85% by mass, 0.25 mol / L) of 97% by mass tetramethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.354 g of a 25% by mass aqueous solution of tetramethylammonium hydroxide, and 95.6 g of ultrapure water were mixed to prepare a solution containing a bromine-containing compound (liquid B) in a manner having the composition shown in Table 6.

[0232] (Manufacturing of treatment liquid)

[0233] 20 g of liquid B was added to 80 g of liquid A obtained by the above operation to obtain 100 g of a treatment liquid having the composition described in Tables 1 to 4.

[0234] (evaluate)

[0235] The obtained treatment liquid was evaluated by the same method as in Example 1.

[0236] <Examples 25 to 30>

[0237] Examples 25 to 30 were evaluated by preparing treatment solutions in the same manner as Example 24, with the bromine-containing compound concentration, oxidant concentration, alkaline compound concentration, and pH being the compositions of Tables 1 to 4, according to the composition, mixing ratio, and mixing method shown in Table 6. The reaction time in Table 6 refers to the time from the mixing of solution A and solution B until the etching rate stabilizes, that is, until the hypobromite ion (BrO － ) The concentration stabilization time is the time until the concentration change of the hypobromite ion concentration measured every 1 minute falls within ±5%.

[0238] <Example 31>

[0239] (Manufacturing of treatment liquid)

[0240] To 94.43 g of ultrapure water were added 1.14 g (equivalent to 1.14 mass %, 0.05 mol / L) of periodic acid (manufactured by FUJI FILM Wako Pure Chemical Industries, Ltd.) and 0.79 g (equivalent to 0.77 mass %, 0.05 mol / L) of tetramethylammonium bromide (manufactured by Tokyo Chemical Industry, 97 mass %). After standing for 3 hours, a 25 mass % tetramethylammonium hydroxide aqueous solution was added until the pH reached 11, thereby obtaining 100 g of a treatment liquid having the composition described in Tables 1 to 4.

[0241] (evaluate)

[0242] The obtained treatment liquid was evaluated by the same method as in Example 1.

[0243] <Example 32>

[0244] (Manufacturing of treatment liquid)

[0245] To 78.21 g of ultrapure water were added 0.79 g (equivalent to 0.77% by mass, 0.05 mol / L) of tetramethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., 97% by mass) and 16.0 g of a 25% by mass aqueous solution of tetramethylammonium hydroxide, and then 5.0 g (equivalent to 5.0% by mass, 0.22 mol / L) of periodic acid (manufactured by FUJI FILM Wako Pure Chemical Industries, Ltd.) was added to obtain 100 g of a treatment liquid having the composition shown in Tables 1 to 4.

[0246] (evaluate)

[0247] The obtained treatment liquid was evaluated by the same method as in Example 1.

[0248] <Examples 33 to 35>

[0249] Examples 33 to 35 According to the conditions described in Table 7, an oxidant was produced by the same method as in Example 1, and treatment liquids were prepared by the same method as in Example 1 so that the bromine-containing compound concentration, oxidant concentration, alkaline compound concentration, and pH had the compositions shown in Tables 1 to 4. Evaluation was performed by the same method as in Example 1.

[0250] <Example 36>

[0251] (Manufacture of Tetramethylammonium Bromide)

[0252] 90.88 g of ultrapure water was added to 9.12 g of 25% tetramethylammonium hydroxide aqueous solution (manufactured by FUJI FILM Wako Pure Chemical Industries, Ltd.) to prepare a 2.28% tetramethylammonium hydroxide aqueous solution. Subsequently, 95.7 g of ultrapure water was added to 4.3 g of 47% hydrobromic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) to prepare a 2.02% hydrobromic acid. 50 g of the 2.28% tetramethylammonium hydroxide aqueous solution and 50 g of the 2.02% hydrobromic acid were mixed to obtain 100 g of the tetramethylammonium bromide aqueous solution described in Table 9.

[0253] (Manufacturing of treatment liquid)

[0254] 20 g of 3.85% tetramethylammonium bromide aqueous solution was added to 80 g of a mixed solution of tetramethylammonium hypochlorite aqueous solution and tetramethylammonium hydroxide obtained in the same manner as in Example 1 to obtain 100 g of a treatment liquid having the composition described in Tables 1 to 4.

[0255] (evaluate)

[0256] The obtained treatment liquid was evaluated by the same method as in Example 1.

[0257] <Example 37>

[0258] By the same method as in Example 3, a treatment liquid having the composition described in Tables 1 to 4 was obtained. The pH of the treatment liquid just after manufacture, the etching rate of ruthenium dioxide, the amount of RuO4 gas produced, and the hypobromous acid ion concentration were evaluated. The evaluation of the etching rate of ruthenium dioxide was performed by the above-mentioned "calculation method of etching rate of ruthenium dioxide". The evaluation of the amount of RuO4 gas produced was performed by the above-mentioned "quantitative analysis of RuO4 gas". The evaluation of the hypobromous acid ion concentration was performed by the above-mentioned "calculation method of hypobromous acid ion concentration". The stability evaluation of the etching rate was performed as described below. The etching rate of the manufactured treatment liquid was evaluated every 10 hours by the above-mentioned "calculation method of etching rate of ruthenium dioxide". The time when the obtained etching rate increased or decreased within ±20% relative to the etching rate just after manufacture was taken as the stabilization time of the etching rate.

[0259] <Example 38>

[0260] A treatment liquid having a pH of 12 was prepared, containing 0.075 g (0.05 mol / L) of sodium bromate (Wako Pure Chemical Industries, Ltd.), a bromine-containing compound, an oxidant, and an alkaline compound at the same concentrations as in Example 1 shown in Table 1. The obtained treatment liquid was evaluated in the same manner as in Example 1.

[0261] <Example 39>

[0262] A treatment liquid having a pH of 12 was prepared, containing 0.075 g (0.05 mol / L) of sodium bromate (Wako Pure Chemical Industries, Ltd.), a bromine-containing compound, an oxidant, and an alkaline compound at the same concentrations as in Example 10 shown in Table 1. The obtained treatment liquid was evaluated in the same manner as in Example 1.

[0263] The composition of the treatment liquid and the evaluation results are shown in Tables 1 to 5. As shown in Table 5, in Comparative Examples 1 and 2, ruthenium was not etched at all. In Comparative Example 3 where etching was possible, the etching rate and stability were low, and the amount of RuO4 gas generated was twice the allowable value, so the etching rate, stability, and RuO4 gas suppression ability could not be satisfied. In contrast, for the treatment liquid of the present embodiment, it was confirmed that the following three properties were satisfied: not only was the etching rate of ruthenium fast, but the stability of the etching rate was excellent, and the RuO4 gas suppression effect was high. According to the results of Examples 24 to 30, it was confirmed that the time until the etching rate of these treatment liquids stabilized was sufficiently fast to within 1 hour. Example 37 is a treatment liquid with the same hypobromite ion concentration and the same pH as Example 3, and it can be confirmed that it also has high etching performance for ruthenium dioxide. In Examples 38 and 39, BrO is present in the treatment liquid. － BrO3 － Br － , thereby improving the stability of the etching rate.

[0264] [Table 1]

[0265]

[0266] [Table 2]

[0267]

[0268] [Table 3]

[0269]

[0270] [Table 4]

[0271]

[0272] [Table 5]

[0273]

[0274] [Table 6]

[0275]

[0276] [Table 7]

[0277]

[0278] [Table 8]

[0279]

[0280] [Table 9]

[0281]

Claims

1. A ruthenium semiconductor treatment liquid, comprising at least: a bromine-containing compound, an oxidant, an alkaline compound and water, wherein the amount of the bromine-containing compound added is 0.008 mass % or more and less than 2.0 mass % in terms of bromine element relative to the total mass, the amount of the oxidant added is 0.1 mass ppm or more and 10 mass % or less, and the pH is 8 or more and 14 or less, the treatment liquid contains hypobromite ions and the concentration of the hypobromite ions is 0.001 mol / L or more and 0.20 mol / L or less in terms of bromine element, The bromine-containing compound is a bromine salt or hydrogen bromide, The oxidant is a hypochlorous acid compound or ozone, Hypobromite ion is obtained by oxidizing a bromine-containing compound with an oxidizing agent.

2. The ruthenium semiconductor processing liquid according to claim 1, wherein The ruthenium is a ruthenium-based metal or a ruthenium alloy.

3. A ruthenium semiconductor processing liquid, comprising at least: a bromine-containing compound, an oxidant, an alkaline compound and water, wherein the amount of the bromine-containing compound added is 0.008% by mass or more and less than 2.0% by mass in terms of the amount of bromine element relative to the total mass, the amount of the oxidant added is 0.1 ppm by mass or more and 10% by mass or less, and the pH is 8 or more and 14 or less, the bromine-containing compound is a compound containing hypobromite ions, and the concentration of the hypobromite ions is 0.001 mol / L or more and 0.20 mol / L or less in terms of the amount of bromine element, The bromine-containing compound is a bromine salt or hydrogen bromide, The oxidant is a hypochlorous acid compound or ozone.

4. The ruthenium semiconductor processing liquid according to claim 3, wherein The ratio of the hypobromite ion to 1 mol of the bromine element contained in the semiconductor processing liquid exceeds 0.5 mol.

5. The ruthenium semiconductor processing liquid according to any one of claims 1 to 4, wherein The amount of the bromine-containing compound added is 0.08% by mass or more and less than 2.0% by mass in terms of the amount of bromine element.

6. The ruthenium semiconductor processing liquid according to any one of claims 1 to 4, wherein The amount of the bromine-containing compound added is 0.01 mass % or more and less than 2 mass % in terms of bromine element amount, and the amount of the oxidizing agent added is 0.1 mass % or more and 10 mass % or less.

7. The ruthenium semiconductor processing liquid according to claim 1 or 3, wherein The bromide salt is tetraalkylammonium bromide.

8. The ruthenium semiconductor processing liquid according to claim 1 or 3, wherein The alkaline compound is tetramethylammonium hydroxide.

9. The ruthenium semiconductor processing liquid according to claim 1 or 3, wherein The pH is 12 or more and 14 or less. 10 . A method for producing a ruthenium semiconductor processing liquid according to claim 1 , comprising: mixing the bromine-containing compound into an aqueous solution of the oxidizing agent and the alkaline compound.

11. A method for processing a substrate, comprising: manufacturing a semiconductor processing liquid by the manufacturing method according to claim 10, and then etching a ruthenium-based metal film and / or a ruthenium alloy film deposited on the substrate using the semiconductor processing liquid.

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