Ruthenium semiconductor processing liquid and method for producing same

Abstract

The invention relates to a ruthenium semiconductor processing liquid and a manufacturing method thereof. A treatment liquid for a ruthenium semiconductor, the treatment liquid containing hypobromous acid ions, the amount of the hypobromous acid ions being 0.001 mol / L to 0.20 mol / L (inclusive).

Description

[0001] This application is a divisional application of the following application:

[0002] Title of Invention: Processing Liquid for Semiconductor Use Containing Ruthenium and Method for Producing the Same

[0003] International Application Date: July 8, 2020

[0004] International Application Number: PCT / JP2020 / 026635

[0005] National Application Number: 202080068032.9 Technical Field

[0006] The present invention relates to a processing liquid used for etching ruthenium of a semiconductor wafer containing ruthenium or the like in a manufacturing process of a semiconductor element. Background Art

[0007] In recent years, as the design rules of semiconductor elements have been refined, there has been a tendency for the 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 required. Therefore, as a wiring material, a wiring material having higher electromigration resistance and a reduced resistance value than conventional wiring materials is desired.

[0008] Compared with conventional wiring materials such as aluminum and copper, ruthenium has high electromigration resistance. For the reason of reducing the resistance value of wiring, in particular, ruthenium has attracted attention as a wiring material for semiconductor elements with a design rule of 10 nm or less. In addition, not only as a wiring material, but also for ruthenium, electromigration can be prevented when copper is used as the wiring material. Therefore, the use of ruthenium as a barrier metal for copper wiring has also been studied.

[0009] Furthermore, in the wiring formation process of semiconductor elements, when ruthenium is selected as the wiring material, similar to conventional wiring materials, wiring is formed by dry etching or wet etching. However, ruthenium is difficult to be removed by etching in a dry process using an etching gas or etching by CMP polishing. Therefore, more precise etching is desired. Specifically, wet etching has attracted attention.

[0010] In the case of wet etching of ruthenium, the dissolution rate of ruthenium, that is, the etching rate, is important. If the etching rate is high, ruthenium can be dissolved in a short time, and the number of wafers processed per unit time can be increased.

[0011] In the case of wet etching of ruthenium under alkaline conditions, ruthenium is, for example, RuO 4 － 、RuO 4 2－dissolves in the treatment liquid in the form of RuO 4 － , RuO 4 2－ changes to RuO 4 in the treatment liquid, and a part of it gasifies and is discharged into the gas phase. RuO 4 is strongly oxidizing, so it is not only harmful to the human body, but also easily reduced to produce RuO 2 particles. Generally, particles will cause a reduction in the yield, so it becomes a very serious problem in the semiconductor formation process. Based on such a background, it is very important to suppress the generation of RuO 4 gas.

[0012] As a treatment liquid for etching ruthenium from such semiconductor wafers, in Patent Document 1, a treatment liquid for wafers with ruthenium is proposed, which contains hypochlorite ions and a solvent, and has a pH exceeding 7 and less than 12.0 at 25°C. This liquid shows that it contains hypochlorite ions and can remove ruthenium and tungsten attached to the end faces and back faces of semiconductor wafers.

[0013] In Patent Document 2, an etching composition for ruthenium-based metals is described, which is characterized in that a bromine-containing compound, an oxidizing agent, a basic compound, and water are added and mixed. With respect to the total mass, the addition amount of the bromine-containing compound is 2 to 25% by mass in terms of the amount of bromine element, the addition amount of the oxidizing agent is 0.1 to 12% by mass, and the pH is 10 or more and less than 12.

[0014] Prior Art Documents

[0015] Patent Documents

[0016] Patent Document 1: International Publication No. 2019 / 142788

[0017] Patent Document 2: International Publication No. 2011 / 074601 Summary of the Invention

[0018] Problems to be Solved by the Invention

[0019] Regarding etching ruthenium from a semiconductor wafer with ruthenium, it is important to balance the etching rate of ruthenium and the suppression of RuO 4 gas. However, according to the research of the present inventors, it can be understood that there is room for improvement in the following aspects in the conventional treatment liquids described in the prior art documents.

[0020] For example, in Patent Document 1, a treatment liquid with a pH exceeding 7 and less than 12.0 is described as a treatment liquid for wafers with ruthenium. In the treatment liquid described in Patent Document 1, the etching rate of ruthenium is sufficient, but for RuO 4The gas is not mentioned. In fact, in the method described in Patent Document 1, it is impossible to suppress the generation of RuO 4 gas. That is, for the treatment liquid of the wafer having ruthenium described in Patent Document 1, it is difficult to balance the etching rate of ruthenium and the control of RuO 4 gas.

[0021] The etching composition for ruthenium-based metal described in Patent Document 2 is characterized in that the pH is 10 or more and less than 12. In this pH range, RuO 4 gas is generated along with the etching of ruthenium, so there is room for improvement. In addition, in Patent Document 2, the suppression of RuO 4 gas is not mentioned. In fact, in the method described in Patent Document 2, it is impossible to suppress the generation of RuO 4 gas. In addition, the following problems exist with this etching composition: poor chemical solution stability, and the etching rate of ruthenium will vary greatly over time. Moreover, as a method for preparing this treatment liquid, it is shown that an oxide obtained by oxidizing a bromine-containing compound with an oxidant under acidic conditions is mixed with an alkali compound, and the pH is appropriately adjusted to be alkaline. However, when mixing this oxide with this alkali compound, it is necessary to wait for the generation of bromine gas for several hours, and a large amount of the high-concentration alkali compound needs to be added to make the pH change from acidic to alkaline, etc., so there is room for improvement in the operation of the treatment liquid. Therefore, the present invention has been completed in view of the above background art, and its object is to provide a treatment liquid and a method for manufacturing the treatment liquid, the treatment liquid can etch ruthenium attached to the surface, end face, and back face of a semiconductor wafer at a sufficient speed, its speed stability is excellent, and it can suppress the generation of RuO 4 gas.

[0022] Means for solving the problems

[0023] The inventors of the present invention conducted in-depth research to solve the above problems. Then, it was found that ruthenium can be etched at high speed by treating ruthenium with a treatment liquid containing hypobromite ions. Moreover, it was found that ruthenium can be etched at a higher speed by oxidizing the bromine-containing compound added in the alkaline treatment liquid with an oxidant in the treatment liquid to form a bromine oxide. Moreover, it was found that by setting an appropriate pH range, bromine-containing compound concentration range, and oxidant concentration range, it can be made stable at a sufficient etching speed and suppress the generation of RuO 4 gas, thus completing the present invention.

[0024] That is, the constitution of the present invention is as follows.

[0025] Item 1: A treatment liquid for a semiconductor of ruthenium, which contains hypobromite ions.

[0026] Item 2: The processing liquid for semiconductors according to Item 1, wherein the hypobromite ion is 0.001 mol / L or more and 0.20 mol / L or less.

[0027] Item 3: The processing liquid for semiconductors according to Item 1 or 2, wherein the hypobromite ion is 0.01 mol / L or more and 0.10 mol / L or less.

[0028] Item 4: The processing liquid for semiconductors according to any one of Items 1 to 3, wherein the processing liquid for semiconductors further contains an oxidizing agent, and the redox potential of the oxidizing agent exceeds the redox potential of the hypobromite ion / Br － system.

[0029] Item 5: The processing liquid for semiconductors according to Item 4, wherein the oxidizing agent contained in the processing liquid for semiconductors is a hypochlorite ion or ozone.

[0030] Item 6: The processing liquid for semiconductors according to any one of Items 1 to 5, wherein the processing liquid for semiconductors further contains a tetraalkylammonium ion.

[0031] Item 7: The processing liquid for semiconductors according to Item 6, wherein the tetraalkylammonium ion is a tetramethylammonium ion.

[0032] Item 8: The processing liquid for semiconductors according to any one of Items 1 to 7, wherein the proportion of the hypobromite ion in 1 mole of the bromine element contained in the processing liquid for semiconductors exceeds 0.5 mole.

[0033] Item 9: The processing liquid for semiconductors according to any one of Items 1 to 8, wherein the pH of the processing liquid is 8 or more and 14 or less.

[0034] Item 10: The processing liquid for semiconductors according to any one of Items 1 to 9, wherein the pH of the processing liquid is 12 or more and less than 13.

[0035] Item 11: A processing liquid for ruthenium semiconductors, which contains at least: a bromine-containing compound, an oxidizing agent, a basic compound, and water. Based on the total mass, the addition amount of the bromine-containing compound is 0.008% by mass or more and less than 10% by mass in terms of the amount of bromine element, the addition amount of the oxidizing agent is 0.1 mass ppm or more and 10% by mass or less, and the pH is 8 or more and 14 or less.

[0036] Item 12: The processing liquid for ruthenium semiconductors according to Item 11, wherein the addition amount of the bromine-containing compound is 0.08% by mass or more and less than 2.0% by mass in terms of the amount of bromine element.

[0037] Item 13: The treatment liquid for a semiconductor using ruthenium according to Item 11 or 12, wherein the addition amount of the bromine-containing compound is 0.01% by mass or more and less than 2% by mass in terms of the amount of bromine element, and the addition amount of the oxidizing agent is 0.1% by mass or more and 10% by mass or less.

[0038] Item 14: The treatment liquid for a semiconductor according to any one of Items 11 to 13, wherein the ruthenium is a ruthenium-based metal or a ruthenium alloy.

[0039] Item 15: The treatment liquid for a semiconductor according to any one of Items 11 to 14, wherein the oxidizing agent is a hypochlorous acid compound or ozone.

[0040] Item 16: The treatment liquid for a semiconductor according to any one of Items 11 to 15, wherein the bromine-containing compound is a bromide salt or hydrogen bromide.

[0041] Item 17: The treatment liquid for a semiconductor according to Item 16, wherein the bromide salt is tetraalkylammonium bromide.

[0042] Item 18: The treatment liquid for a semiconductor according to Item 17, wherein the tetraalkylammonium bromide is tetramethylammonium bromide.

[0043] Item 19: The treatment liquid for a semiconductor according to any one of Items 11 to 18, wherein the alkali compound is tetramethylammonium hydroxide.

[0044] Item 20: The treatment liquid for a semiconductor according to any one of Items 11 to 19, wherein the pH is 12 or more and 14 or less.

[0045] Item 21: The treatment liquid for a semiconductor according to any one of Items 11 to 20, wherein the pH is 12 or more and less than 13.

[0046] Item 22: The treatment liquid for a semiconductor according to Item 14, wherein the ruthenium-based metal contains 70 atomic% or more of ruthenium.

[0047] Item 23: The treatment liquid for a semiconductor according to Item 14, wherein the ruthenium-based metal is metallic ruthenium.

[0048] Item 24: The treatment liquid for a semiconductor according to Item 14, wherein the ruthenium alloy contains 70 atomic% or more and 99.99 atomic% or less of ruthenium.

[0049] Item 25: The treatment liquid for a semiconductor according to any one of Items 11 to 24, wherein the proportion of hypobromite ions in 1 mole of bromine element contained in the treatment liquid for a semiconductor exceeds 0.5 mole.

[0050] Item 26: A manufacturing method, which is the manufacturing method of the processing liquid for semiconductors described in any one of Items 11 to 25, and has: a step of mixing a solution containing the oxidizing agent and the alkali compound with the bromine-containing compound.

[0051] Item 27: A manufacturing method, which is the manufacturing method of the processing liquid for semiconductors described in any one of Items 11 to 25, and has: a step of mixing the bromine-containing compound into an aqueous solution of the oxidizing agent and the alkali compound.

[0052] Item 28: A method for processing a substrate, which, after manufacturing a processing liquid for semiconductors by the manufacturing method described in Item 26 or 27, etches a ruthenium-based metal film and / or a ruthenium alloy film deposited on the substrate using the processing liquid for semiconductors.

[0053] Item 29: A manufacturing method of a processing liquid for semiconductors of ruthenium, which has: a step of mixing a solution containing an alkali compound with hypobromous acid, hypobromite, bromine water, or bromine gas.

[0054] Item 30: A manufacturing method of a processing liquid for semiconductors of ruthenium, which has: a step of mixing a solution containing a hypochlorous acid compound and an alkali compound with a bromine-containing compound.

[0055] Item 31: The manufacturing method of the processing liquid for semiconductors 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.

[0056] Item 32: The manufacturing method of the processing liquid for semiconductors according to any one of Items 29 to 31, wherein the solution is an aqueous solution.

[0057] Item 33: The manufacturing method according to any one of Items 29 to 32, wherein the ruthenium is a ruthenium-based metal or a ruthenium alloy.

[0058] Item 34: The manufacturing method of the processing liquid for semiconductors according to any one of Items 29 to 33, wherein the alkali compound is tetramethylammonium hydroxide.

[0059] Item 35: The manufacturing method of the processing liquid for semiconductors according to any one of Items 30 to 34, wherein the bromine-containing compound is a bromide salt or hydrogen bromide.

[0060] Item 36: The manufacturing method of the processing liquid for semiconductors according to Item 35, wherein the bromide salt is an onium bromide.

[0061] Item 37: The manufacturing method of the processing liquid for semiconductors according to Item 36, wherein the onium bromide is a quaternary onium bromide or a tertiary onium bromide.

[0062] Item 38: The method for manufacturing a processing liquid for a semiconductor according to Item 37, wherein the quaternary ammonium bromide is tetraalkylammonium bromide.

[0063] Item 39: The method for manufacturing a processing liquid for a semiconductor according to Item 38, wherein the tetraalkylammonium bromide is manufactured from tetraalkylammonium hydroxide and bromide ions.

[0064] Item 40: The method for manufacturing a processing liquid for a semiconductor according to Item 38 or 39, wherein the tetraalkylammonium bromide is manufactured from tetraalkylammonium hydroxide and hydrogen bromide.

[0065] Item 41: The method for manufacturing a processing liquid for a semiconductor according to Item 35, wherein the bromide salt is ammonium bromide, sodium bromide, or potassium bromide.

[0066] Item 42: The method for manufacturing a processing liquid for a semiconductor according to any one of Items 30 to 41, wherein the solution containing a hypochlorous acid compound is a tetraalkylammonium hypochlorite solution.

[0067] Item 43: The method for manufacturing a processing liquid for a semiconductor according to Item 42, wherein, as the process for manufacturing the tetraalkylammonium hypochlorite solution, it includes: a preparation process of preparing a tetraalkylammonium hydroxide solution; and a reaction process of bringing the tetraalkylammonium hydroxide solution into contact with chlorine, the carbon dioxide concentration in the gas phase part in the reaction process is 100 volume ppm or less, and the pH of the liquid phase part in the reaction process is 10.5 or more.

[0068] Item 44: The method for manufacturing a processing liquid for a semiconductor according to Item 43, wherein the number of carbon atoms of the alkyl group of the tetraalkylammonium hydroxide prepared in the preparation process is 1 to 10.

[0069] Item 45: The method for manufacturing a processing liquid for a semiconductor according to Item 43 or 44, wherein the reaction temperature in the reaction process is -35°C or higher and 25°C or lower.

[0070] Item 46: The method for manufacturing a processing liquid for a semiconductor according to any one of Items 43 to 45, wherein the carbon dioxide concentration in the tetraalkylammonium hydroxide solution in the reaction process is 0.001 ppm or more and 500 ppm or less.

[0071] Advantages of the Invention

[0072] According to the present invention, in the semiconductor formation process, ruthenium can be wet-etched stably at a sufficiently fast speed, and moreover, the generation of RuO 4 gas can be suppressed. Thereby, not only the wafer processing efficiency per unit time is improved, but also the generation of RuO 2The yield reduction caused by particles can be addressed, and a treatment safe for humans can be achieved, balancing manufacturing costs and safety.

[0073] Moreover, according to the method described in the present invention, by directly oxidizing a bromine-containing composition with an oxidizing agent in an alkaline treatment solution, bromine, hypobromous acid, hypobromite ions, bromous acid, bromite ions, bromic acid, bromate ions, perbromic acid, and perbromate ions can be rapidly produced. Since the treatment solution thus produced contains hypobromite ions, there is no need to wait for a long time for the generation of bromine gas, and ruthenium etching can be immediately carried out, shortening the time required for semiconductor manufacturing.

[0074] Moreover, since there is no need to adjust the pH of the treatment solution from acidic to alkaline, the amount of alkali compounds added to the treatment solution can be significantly reduced, and the operation of the treatment solution becomes easier. Detailed Description

[0075] (Treatment Solution for Semiconductors)

[0076] The treatment solution of the present invention is characterized by containing hypobromite ions (BrO － ). Hypobromite ions are oxidizing agents with strong oxidizing properties. The treatment solution of the present invention containing hypobromite ions can etch ruthenium at high speed under alkaline conditions. Moreover, it is a treatment solution that can suppress the generation of RuO 4 gas and etch ruthenium at a stable etching rate by appropriately selecting the pH, type, and concentration of the oxidizing agent. Therefore, the treatment solution of the present invention is a treatment solution 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, ruthenium semiconductors refer to semiconductors containing ruthenium.

[0077] If the treatment solution of the present invention is used, the generation of RuO 4 gas can be suppressed, and ruthenium attached to the surface, end faces, and back faces of semiconductor wafers can be removed at a sufficient etching rate. The sufficient etching rate in the present invention refers to or more etching rate. If the etching rate of ruthenium is or more, it can be preferably used in etching processes, residue removal processes, cleaning processes, CMP processes, etc. In addition, the amount of RuO 4 gas generated during ruthenium etching depends on treatment conditions (for example, the amount of dissolved ruthenium; the volume of the treatment solution used; the treatment temperature; the volume and material of the container, chamber, etc.). Therefore, when comparing the amount of RuO 4 gas generated, it is important to consider these conditions. Briefly, it can be evaluated based on the generation amount per unit area of the wafer containing ruthenium. The RuO 4The gas is trapped in an appropriate absorbent liquid (e.g., an alkaline solution such as an aqueous NaOH solution). After quantifying the amount of ruthenium in the trapped liquid, it is divided by the area of the wafer used to obtain the RuO production per unit area of the ruthenium-containing wafer. 4 production amount. Therefore, in order to confirm the RuO 4 gas inhibition effect, it is only necessary to compare the RuO 4 gas production amount per unit area. The treatment liquid with a low RuO 4 production amount per unit area can inhibit the production of RuO 4 gas, inhibit the generation of RuO 2 particles, and thus can be preferably used for the etching of ruthenium.

[0078] The treatment liquid in the present invention can etch ruthenium, but does not etch metals such as copper, cobalt, titanium, platinum, titanium nitride, tantalum nitride, etc., or has an extremely small etching rate compared to ruthenium-based metals. Therefore, in semiconductor manufacturing processes, etc., it is also possible to selectively etch ruthenium-based metals without damaging the substrate material containing these metals.

[0079] In the present invention, the stable etching rate of ruthenium means that the etching rate of ruthenium based on the treatment liquid containing hypobromite ions does not change with time. Specifically, when etching multiple wafers having ruthenium (assuming the number of wafers is n) with the same treatment liquid, 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 variation range 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 increase or decrease of the etching rate of ruthenium in the nth wafer relative to the etching rate of ruthenium in the first wafer is within ±20% is set as the stable time of the etching rate. The preferred value of the stable time of the etching rate varies depending on the conditions and manufacturing processes in which the treatment liquid of the present invention is used. For example, a treatment liquid with a stable time of the etching rate of 1 hour or more can be preferably used for semiconductor manufacturing processes. If considering that the operation of the treatment liquid has a time margin and the process time can be flexibly set, a treatment liquid with a stable time of the etching rate of 10 hours or more is more preferred.

[0080] A treatment liquid with an etching rate of ruthenium that does not change with time or a treatment liquid with a long stable time of the etching rate can not only stably perform the etching of ruthenium using the treatment liquid in semiconductor manufacturing processes, but also enable the reuse of the treatment liquid, and thus becomes a treatment liquid that is excellent in terms of productivity and cost.

[0081] 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 herein refers to a salt containing hypobromite ions or a solution containing such a 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 viewpoint of efficiently generating hypobromite ions, the treatment liquid is preferably 50 °C or lower. If the treatment liquid is 50 °C or lower, not only can hypobromite ions be efficiently generated, but also the generated hypobromite ions can be stably used for ruthenium etching. Moreover, in order to dissolve more bromine in the treatment liquid, the temperature of the treatment liquid is more preferably 30 °C or lower, and most preferably 25 °C or lower. There is no particular limitation on the lower limit of the temperature of the treatment liquid, and it is preferably that the treatment liquid does not freeze. Therefore, the treatment liquid is preferably -35 °C or higher, more preferably -15 °C or higher, and most preferably 0 °C or higher. The pH of the treatment liquid into which the bromine gas is blown is not particularly limited, and as long as the pH of the treatment liquid is alkaline, the hypobromite ions can be immediately used for ruthenium etching after being generated.

[0082] Moreover, in the case where hypobromite ions are generated by blowing bromine gas into the treatment liquid, if the treatment liquid contains bromide ions (Br － ), the solubility of bromine gas (Br 2 ) is increased. The reason is that the dissolved Br 2 reacts with Br － , Br 3 － to form complex ions such as Br 3 － , Br 5 － , and is stabilized in the treatment liquid. A treatment liquid containing more Br 2 , Br － , Br 3 － , Br 5 － etc. can generate more hypobromite ions, and thus can be preferably used as the treatment liquid of the present invention.

[0083] In addition, by oxidizing a bromine-containing compound with an oxidizing agent, hypobromite ions can be produced in the treatment liquid.

[0084] In order to add hypobromite ions to the treatment liquid in the form of a compound, hypobromous acid, bromine water, and / or hypobromite can be added. As the hypobromite, sodium hypobromite, potassium hypobromite, and tetraalkylammonium hypobromite are preferred, and hypobromous acid or tetraalkylammonium hypobromite is further preferred in terms of not containing metal ions that cause problems in semiconductor manufacturing.

[0085] The tetraalkylammonium hypobromite can be easily obtained by introducing bromine gas into a tetraalkylammonium hydroxide solution. In addition, it can also be obtained by mixing hypobromous acid with a tetraalkylammonium hydroxide solution. Moreover, by using an ion exchange resin to replace the cation contained in a hypobromite such as sodium hypobromite with a tetraalkylammonium ion, tetraalkylammonium hypobromite can also be obtained.

[0086] The concentration of the hypobromite ion in the treatment liquid of the present invention is not particularly limited as long as it does not deviate from the purpose of the present invention. It is preferably 0.001 mol / L or more and 0.20 mol / L or less in terms of the amount of bromine element contained in the hypobromite ion. When it is less than 0.001 mol / L, the etching rate of ruthenium is slow and the practicality is low. On the other hand, when it exceeds 0.20 mol / L, the decomposition of the hypobromite ion is likely to occur, so the etching rate of ruthenium is not easily stabilized. In order to stably etch ruthenium at a sufficient rate, the concentration of the hypobromite ion is preferably 0.001 mol / L or more and 0.20 mol / L or less in terms of the amount of bromine element contained in the hypobromite ion, more preferably 0.005 mol / L or more and 0.20 mol / L or less, and most preferably 0.01 mol / L or more and 0.10 mol / L or less.

[0087] In order to slow down the decrease in the etching rate of ruthenium and stabilize the etching rate, it is preferable that the proportion of hypobromite ion in 1 mole of bromine element contained in the treatment liquid exceeds 0.5 mole. As described above, the hypobromite ion is easily converted to Br － by the oxidation reaction and decomposition reaction of ruthenium. Br － does not etch ruthenium. Therefore, in order to perform stable ruthenium etching, it is important to rapidly oxidize Br － in the treatment liquid to hypobromite ion and maintain a high concentration of chemical species (chemical species) having a high ruthenium etching ability (hypobromite ion; BrO － ). When the proportion of hypobromite ion in 1 mole of bromine element contained in the treatment liquid of the present invention exceeds 0.5 mole, that is, when more than half of the total bromine element in the treatment liquid exists as BrO － , the concentration of the chemical species having a ruthenium etching ability can be regarded as sufficiently high, and the etching rate of ruthenium is stabilized.

[0088] The concentration of hypobromite ions in the treatment liquid can be confirmed by using widely known methods. For example, if ultraviolet-visible spectrophotometry is used, it is easy to confirm the absorption caused by hypobromite ions, and the concentration of hypobromite ions can be obtained from the intensity of its absorption peak (around 330 nm approximately, depending on the pH of the treatment liquid, the concentration of hypobromite ions, etc.). Moreover, the concentration of hypobromite ions can also be obtained by iodine titration. In addition, the concentration of hypobromite ions can also be obtained based on the oxidation-reduction potential (ORP) and pH of the treatment liquid. From the viewpoint of non-contact and continuous measurement, it is most preferable to use the measurement by ultraviolet-visible spectrophotometry. It should be noted that when measuring the concentration of hypobromite ions by ultraviolet-visible spectrophotometry, in the case of the presence of absorption caused by other chemical substances, by performing data processing such as spectral segmentation and baseline correction, and appropriate selection of reference, etc., the concentration of hypobromite ions can be obtained with sufficient accuracy.

[0089] Hypobromous acid (HBrO) and hypobromite ions (BrO － ) have an acid dissociation constant (pK a ) of 8.6. Therefore, in the case of a low pH, etc., HBrO and BrO － may coexist depending on the pH of the treatment liquid. When the treatment liquid contains HBrO and BrO － , the total concentration of HBrO and BrO － can be regarded as the concentration of the above-mentioned hypobromite ions.

[0090] The details of the mechanism by which hypobromite ions dissolve ruthenium are not clear. It is speculated that ruthenium is oxidized by hypobromite ions or hypobromous acid generated from hypobromite ions in the treatment liquid to generate RuO 4 , RuO 4 － or RuO 4 2－ , and thus it dissolves in the treatment liquid. By dissolving ruthenium in the form of RuO 4 － or RuO 4 2－ , the amount of RuO 4 gas generation can be reduced, and the generation of RuO 2 particles can be inhibited. In order to dissolve ruthenium in the form of RuO 4 － or RuO 4 2－ , the pH of the treatment liquid is preferably alkaline, more preferably 8 or more and 14 or less, further preferably 12 or more and 14 or less, and most preferably 12 or more and less than 13. If the pH of the treatment liquid is 12 or more and less than 13, ruthenium is in the form of RuO 4 － or RuO4 2－ dissolves in the treatment liquid in the form of 2－ , so that the generation amount of RuO 4 gas can be greatly reduced, and the generation of RuO 2 particles can be inhibited. On the other hand, when the pH of the treatment liquid is less than 8, ruthenium is easily oxidized to RuO 2 , RuO 4 , so there is a tendency for the amount of RuO 2 particles to increase and the generation amount of RuO 4 gas to increase. In addition, if the pH exceeds 14, the dissolution of ruthenium is not likely to occur, and it is difficult to obtain a sufficient ruthenium etching rate, so the production efficiency in semiconductor manufacturing is reduced.

[0091] To adjust the pH of the treatment liquid, an acid or a base can be added to the treatment liquid. As the acid, it can be any of inorganic acids and organic acids. If an example is listed, it is hydrofluoric acid, hydrochloric acid, hydrobromic acid, nitric acid, acetic acid, sulfuric acid, persulfuric acid, formic acid, carboxylic acids such as acetic acid, etc. In addition, widely known acids for semiconductor treatment liquids can also be used, without any limitation. As the base, from the viewpoint of not containing metal ions that cause problems in semiconductor manufacturing, an organic base is preferably used. If an example of the organic base is listed, it is tetraalkylammonium hydroxide composed of tetraalkylammonium ions and hydroxide ions. If examples of the tetraalkylammonium hydroxide are listed, they can be: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Among them, from the viewpoint of having a large number of hydroxide ions per unit weight and being able to easily obtain a high-purity product, the organic base is preferably tetraalkylammonium hydroxide, and more preferably tetramethylammonium hydroxide.

[0092] The above-mentioned tetraalkylammonium ions contained in the treatment liquid can be one kind or a combination of multiple kinds can be used.

[0093] The treatment liquid of the present invention preferably contains an oxidizing agent. By including the oxidizing agent in the treatment liquid of the present invention, it plays a role of re-oxidizing the bromide ions (Br － ) generated by decomposing hypobromite ions.

[0094] When ruthenium is oxidized, hypobromite ions are reduced to Br － . In addition, hypobromite ions are easily decomposed naturally in the treatment liquid, and a part of them changes to Br － . Moreover, the decomposition of hypobromite ions is promoted by ultraviolet rays and visible light, and a part of them changes to Br － . Moreover, hypobromite ions also decompose due to heating, contact with acids, and contact with metals, and a part of them changes to Br － . The Br －Ru is insoluble. Therefore, if the reduction or decomposition of hypobromite ions proceeds, the etching rate of Ru decreases. The treatment liquid contains an appropriate oxidizing agent, whereby Br generated by reduction or decomposition can be oxidized to hypobromite ions, and the decrease in the etching rate of Ru can be slowed down. That is, the treatment liquid contains hypobromite ions and an appropriate oxidizing agent, whereby the stabilization time of the etching rate becomes longer. － The oxidizing agent optionally contained in the treatment liquid preferably has an oxidation-reduction potential between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent exceeding the oxidation-reduction potential of the hypobromite ion / Br system. If such an oxidizing agent is used, Br can be oxidized to hypobromite ions. The oxidation-reduction potential between the oxidizing agent optionally contained in the treatment liquid and the chemical species generated by the reduction of the oxidizing agent varies depending on the concentration of the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent, the temperature of the solution, the pH, etc., but as long as the oxidation-reduction potential between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent exceeds the oxidation-reduction potential of the hypobromite ion / Br system, it is sufficient.

[0095] The oxidizing agent optionally contained in the treatment liquid preferably has an oxidation-reduction potential between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent exceeding the oxidation-reduction potential of the hypobromite ion / Br system. － If such an oxidizing agent is used, Br can be oxidized to hypobromite ions. － The oxidation-reduction potential between the oxidizing agent optionally contained in the treatment liquid and the chemical species generated by the reduction of the oxidizing agent varies depending on the concentration of the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent, the temperature of the solution, the pH, etc., but as long as the oxidation-reduction potential between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent exceeds the oxidation-reduction potential of the hypobromite ion / Br system, it is sufficient. － system.

[0096] On the other hand, the upper limit of the oxidation-reduction potential between the oxidizing agent optionally contained in the treatment liquid and the chemical species generated by the reduction of the oxidizing agent is not particularly limited as long as it does not deviate from the object of the present invention. However, when the oxidation-reduction potential is higher than the oxidation-reduction potential of the RuO / RuO system (1.0 V vs. SHE), RuO dissolved in the treatment liquid is oxidized by the oxidizing agent to RuO, and the generation of RuO gas may increase. In such a case, by appropriately adjusting the amount of the oxidizing agent added to the treatment liquid and the timing of adding the oxidizing agent, the oxidation from RuO to RuO can be suppressed, and the amount of RuO gas generation can be controlled. 4 － / RuO 4 system (1.0 V vs. SHE), the RuO dissolved in the treatment liquid is oxidized by the oxidizing agent to RuO, and the generation of RuO gas may increase. 4 － is oxidized to RuO by the oxidizing agent. 4 RuO 4 gas generation may increase. In such a case, by appropriately adjusting the amount of the oxidizing agent added to the treatment liquid and the timing of adding the oxidizing agent, the oxidation from RuO 4 － to RuO 4 can be suppressed, and the amount of RuO 4 gas generation can be controlled.

[0097] From the viewpoint of not containing metal elements that cause problems in semiconductor manufacturing, the oxidizing agent optionally contained in the treatment liquid of the present invention preferably uses hypochlorite ions or ozone. Among them, in terms of high solubility in the treatment liquid, stable existence in the solution, and easy concentration adjustment, hypochlorite ions are more preferred.

[0098] Hypochlorite ions and ozone can oxidize Br in an alkaline treatment liquid (pH is 8 or more and 14 or less). －The ability to be re-oxidized to hypobromite ions. It can be seen from the following: hypochlorite ion / Cl － The redox potential of the chlorine system is 0.89V, and the redox potential of the ozone / oxygen system is 1.24V. In contrast, the redox potential of the hypobromite ion / Br － system is 0.76V. It should be noted that the above redox potential is the value relative to the standard hydrogen electrode at pH 14 (25°C). Therefore, the treatment liquid of the present invention containing hypobromite ions and hypochlorite ions or ozone can maintain the concentration of hypobromite ions in the treatment liquid at a high concentration by oxidizing Br － to hypobromite ions, so that the etching rate of ruthenium can be stabilized.

[0099] Examples of using hypochlorite ions as an oxidant are shown in Table 8. It can be seen that even at any pH, in terms of redox potential, the hypochlorite ion / Cl － system is higher than the hypobromite ion / Br － system. Thus, for the treatment liquid of the present invention containing both hypobromite ions and hypochlorite ions, the stable time of the etching rate of ruthenium becomes longer, so it can be particularly preferably used. On the other hand, when using an oxidant such as hydrogen peroxide that is alkaline and has weak oxidizing power, Br － cannot be efficiently oxidized to hypochlorite ions, so the etching rate of ruthenium is low.

[0100] The concentration of hypochlorite ions in the treatment liquid of the present invention is not limited as long as it does not deviate from the gist of the present invention, and is preferably 0.1% by mass or more and 10% by mass or less. If the concentration of hypochlorite ions is less than 0.1% by mass, Br － cannot be efficiently oxidized, and the etching rate of ruthenium decreases. On the other hand, if the addition amount of hypochlorite ions is greater than 10% by mass, the stability of hypochlorite ions decreases, so it is not suitable. From the perspective of balancing RuO 4 gas inhibition and the etching rate of ruthenium, the concentration of the oxidant is more preferably 0.3% by mass or more and 7% by mass or less, and most preferably 0.5% by mass or more and 4% by mass or less.

[0101] On the other hand, if the ratio of hypochlorite ions to hypobromite ions is high, the reaction to form bromate ions through the reaction of hypochlorite ions and hypobromite ions proceeds, so the concentration of hypobromite ions decreases.

[0102] The concentration of ozone in the treatment liquid of the present invention is not limited as long as it does not deviate from the gist of the present invention, and is preferably 0.1 mass ppm or more and 1000 mass ppm (0.1% by mass) or less. When it is less than 0.1 mass ppm, Br －The rate of oxidation to hypobromite ions is slow and does not affect the etching rate of ruthenium. In addition, from the viewpoint of stably dissolving ozone in the treatment liquid, the concentration of ozone is more preferably 1 mass ppm or more and 500 mass ppm or less. Moreover, when the concentration of ozone is 5 mass ppm or more and 200 mass ppm or less, Br － can be efficiently oxidized to hypobromite ions, and thus is particularly preferred. In addition, the method for generating ozone and the method for dissolving it in the treatment liquid can be widely known methods without any problems. For example, ozone can be generated by discharging a gas containing oxygen, and a part or all of the ozone can be dissolved in the treatment liquid by bringing the gas containing the ozone into contact with the treatment liquid to prepare 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, a treatment liquid with less reduction in BrO － concentration and stable etching rate can be prepared. On the other hand, when bringing the treatment liquid that has etched ruthenium, that is, the treatment liquid containing RuO 4 / RuO 4 － / RuO 4 2－ etc. into contact with ozone, by bringing ozone into contact with the treatment liquid in small amounts and intermittently each time, an increase in the generation of RuO 4 gas can be prevented.

[0103] The method for generating the above hypochlorite ions is not particularly limited, and hypochlorite ions generated by any method can be preferably used in the treatment liquid of the present invention. As a method for generating hypochlorite ions, for example, adding hypochlorite, blowing in chlorine gas, etc. can be preferably used. Among them, from the viewpoints of easy control of the concentration of hypochlorite ions and easy treatment of the hypochlorite, the method of adding hypochlorite to the treatment liquid is preferred. If such hypochlorites are exemplified, they are tetraalkylammonium hypochlorite, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, hypochlorous acid. Among them, from the viewpoint of not containing metals that cause problems in semiconductor manufacturing, tetraalkylammonium hypochlorite or hypochlorous acid is particularly preferred, and tetraalkylammonium hypochlorite is most preferred from the viewpoint of being able to stably exist even at high concentrations.

[0104] As the above tetraalkylammonium hypochlorite, tetraalkylammonium hypochlorite containing a tetraalkylammonium ion with 1 to 20 carbon atoms in each alkyl group is preferred. Specifically, they are tetramethylammonium hypochlorite, tetraethylammonium hypochlorite, tetrapropylammonium hypochlorite, tetrabutylammonium hypochlorite, tetraamylammonium hypochlorite, tetrahexylammonium hypochlorite. From the viewpoint of having more hypochlorite ions per unit weight, tetramethylammonium hypochlorite and tetraethylammonium hypochlorite are further preferred. Tetramethylammonium hypochlorite can easily obtain a high-purity product, so it is most preferred.

[0105] The method for manufacturing the above-mentioned ammonium tetramethylhypochlorite is not particularly limited, and ammonium tetramethylhypochlorite produced by a widely known method can be used. For example, ammonium tetramethylhypochlorite produced by the following methods can be preferably used: a method of blowing chlorine into tetramethylammonium hydroxide, a method of mixing hypochlorous acid with tetramethylammonium hydroxide, a method of replacing the cation in a hypochlorite solution with a tetramethylammonium using an ion exchange resin, a method of mixing the distillate of a solution containing hypochlorite with tetramethylammonium hydroxide, etc.

[0106] In the treatment liquid of the present invention, hypochlorite ions or ozone and Br are included together － In the case of － Whether Br is continuously oxidized by hypochlorite ions or ozone to BrO － Depends on the molar ratio of hypochlorite ions contained in the treatment liquid to Br － Or the molar ratio of ozone to Br － In the case where the molar concentration of Br present in the treatment liquid － Is higher than the molar concentration of hypochlorite ions or ozone, the total amount of Br － Cannot be oxidized to BrO － . Therefore, the molar concentration of hypochlorite ions or ozone in the treatment liquid of the present invention is preferably higher than the molar concentration of Br － . When a gaseous oxidant such as ozone is introduced into the treatment liquid to oxidize Br － To BrO － , ideally, the total molar number of the gaseous oxidant introduced is more than the molar number of Br － Contained in the treatment liquid.

[0107] As a method for producing hypobromite ions in the treatment liquid, there is a method of oxidizing a bromine-containing compound using an oxidant. The molar ratio of the bromine-containing compound contained in the treatment liquid to the oxidant is preferably determined in consideration of the stoichiometry ratio and reaction rate when the bromine-containing compound reacts with the oxidant to produce hypobromite ions, and the stoichiometry ratio and reaction rate when Br － Reacts with the oxidant to produce hypobromite ions. In fact, for these reactions, multiple factors affect complexly, so it is difficult to obtain an appropriate molar ratio of the bromine-containing compound to 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, but also the Br － Generated by the reduction reaction or decomposition reaction of BrO －Re-oxidized to BrO － , thus stabilizing the etching rate of ruthenium.

[0108] For example, when the bromine-containing compound is tetramethylammonium bromide and the oxidizing agent 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 oxidizing agent. Therefore, it is sufficient that the ratio of the molar concentration of the bromine-containing compound to the concentration of the oxidizing agent is in the range of 0.001 to 100.

[0109] The amount ratio of hypobromite ions to hypochlorite ions contained in the treatment liquid is preferably determined in consideration of the reduction rate of hypobromite ions. More precisely, Br is generated by the reduction reaction and / or decomposition reaction of hypobromite ions － and the rate of oxidation of Br － to BrO － using hypochlorite ions. In fact, for these reactions, multiple factors complexly interact with each other, so it is difficult to obtain an appropriate amount 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, then hypochlorite ions can be used to re-oxidize the Br － generated by the reduction reaction or decomposition reaction of BrO － back to BrO － , stabilizing the etching rate of ruthenium.

[0110] The pH of the ruthenium semiconductor treatment liquid 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 furthermore, a reduction in the amount of RuO 4 gas generation can be expected. The lower the pH, the faster the etching rate of ruthenium, but the lower the pH, the more the amount of RuO 4 gas generation increases. Therefore, when treating a semiconductor wafer containing ruthenium, it is extremely important to select a pH that can balance the etching rate and RuO 4 gas suppression. From this perspective, the pH of the ruthenium semiconductor treatment liquid in the present invention is more preferably set to 12 or more and 14 or less, and further 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 rate, and furthermore, RuO 4 gas generation can be suppressed. When the pH of the treatment liquid is less than 8, there is a tendency for RuO 2 particles to be easily generated.

[0111] The ruthenium contained in the semiconductor wafer to which the treatment liquid of the present invention is applied can be formed by any method. In the film formation of ruthenium, methods widely known in semiconductor manufacturing processes, such as CVD, ALD, PVD, sputtering, plating, etc., can be used. In the present invention, ruthenium refers to ruthenium-based metals or ruthenium alloys.

[0112] In the present invention, "ruthenium-based metals" refers to, in addition to metallic ruthenium, ruthenium metals containing 70 atomic% or more of ruthenium, oxides of ruthenium (RuO X ), nitrides (RuN), oxynitrides (RuNO), etc. Here, the oxide of ruthenium is ruthenium dioxide, ruthenium sesquioxide (trihydrate). In addition, in the present invention, "ruthenium alloy" refers to an alloy containing 70 atomic% or more and 99.99 atomic% or less of ruthenium and containing metals other than ruthenium, and the concentration of the metals other than ruthenium is higher than the inevitably contained concentration. In the present invention, when there is no need to particularly distinguish ruthenium-based metals and ruthenium alloys, they are recorded as ruthenium.

[0113] The ruthenium alloy can also contain any metal other than ruthenium. If an example of the metals contained in the ruthenium alloy is given, it can be listed as: tantalum, silicon, copper, hafnium, zirconium, aluminum, vanadium, cobalt, nickel, manganese, gold, rhodium, palladium, titanium, tungsten, molybdenum, platinum, iridium, etc., and their oxides, nitrides, silicides can also be contained.

[0114] These rutheniums can be intermetallic compounds, ionic compounds, or complexes. In addition, ruthenium can also be exposed on the surface of the wafer, or can be covered by other metals, metal oxide films, insulating films, resists, etc. When ruthenium is covered by other materials and ruthenium dissolution occurs when the ruthenium contacts the treatment liquid of the present invention, it exhibits a RuO 4 gas generation inhibitory effect. Moreover, the treatment liquid of the present invention can suppress the RuO 4 gas generated by the extremely small amount of dissolved ruthenium even when it does not actively dissolve ruthenium, that is, when performing a treatment with ruthenium as the object to be protected.

[0115] For example, in the case of using the treatment liquid of the present invention in the ruthenium wiring formation process, it is as follows. First, a substrate made of a semiconductor (such as Si) is prepared. The prepared substrate is oxidized to form a silicon oxide film on the substrate. Then, an interlayer insulating film made of a low dielectric constant (Low-k) film is formed, and vias are formed at a specified interval. After the vias are formed, ruthenium is buried in the vias by thermal CVD, and further a ruthenium film is formed. By etching this ruthenium film using the treatment liquid of the present invention, planarization is performed while suppressing RuO 4 gas generation. Thus, a ruthenium wiring with suppressed RuO 2 particles and high reliability can be formed.

[0116] 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 alkali compound, and water. The following will be described in order.

[0117] (Bromine-containing compound)

[0118] The bromine-containing compound used in the treatment liquid of the present invention may be any compound as long as it contains a bromine atom and is oxidized by the oxidizing agent described later to generate bromine, hypobromous acid, hypobromite ion, bromous acid, bromite ion, bromic acid, bromate ion, perbromic acid, perbromate ion, bromide ion. If an example is cited, it is preferably at least one selected from the group consisting of bromides and hydrogen bromide. The hydrogen bromide mentioned here may be hydrogen bromide gas or an aqueous solution of hydrogen bromide, that is, hydrobromic acid. Examples of bromides include lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, ammonium bromide, bromonium, etc. Here, bromonium refers to a compound formed by an onium ion and a bromide ion. An onium ion is a compound of a polyatomic cation formed by adding an excess of protons (hydrogen cations) to a monoatomic anion. Specifically, it is an imidazolium ion, a pyrrolidinium ion, a pyridinium ion, a piperidinium ion, an ammonium ion, a phosphonium ion, a fluoronium ion, a chloronium ion, a bromonium ion, an iodonium ion, an oxonium ion, a sulfonium ion, a selenonium ion, a telluronium ion, an arsonium ion, a stibonium ion, a bismuthonium ion, etc. In addition, a compound that generates hypobromous acid or hypobromite ion in the treatment liquid can also be preferably used as the bromine-containing compound. Examples of such compounds include bromohydantoins, bromoisocyanuric acids, bromoaminosulfonic acids, bromochloramines, etc., but are not limited to these. If the compound is more specifically exemplified, it is 1-bromo-3-chloro-5,5-dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin, tribromoisocyanuric acid, etc.

[0119] The above-mentioned bromine-containing compound can be added to the treatment liquid in the form of hydrogen bromide or a bromide, or in the form of a solution containing a bromide, or in the form of bromine gas. From the viewpoint of easy operation in the semiconductor manufacturing process, the bromine-containing compound is preferably mixed with other treatment liquids in the form of a bromide or a solution containing a bromide or hydrogen bromide. The bromine-containing compound contained in the treatment liquid may be one kind or two or more kinds may be used in combination.

[0120] From the viewpoint that the incorporation of metals or metal ions in semiconductor manufacturing causes a reduction in yield, it is desirable that the bromine-containing compound does not contain metals. From the viewpoint of being substantially free of metals, bromonium bromides among bromine gas, hydrogen bromide, and bromine salts are preferably used as the bromine-containing compound of the present invention. Among them, from the viewpoints of being easily obtainable industrially and being easy to handle, tetraalkylammonium bromides, trialkylammonium bromides, and hydrogen bromide among bromonium bromides are further preferably used as the bromine-containing compound of the present invention.

[0121] Tetraalkylammonium bromides are bromine salts composed of ammonium ions or phosphonium ions that can stably exist in the treatment liquid. If an example of a tetraalkylammonium bromide is cited, it is tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetraamylammonium 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, 1-butyl-3-methylpyridinium bromide, etc. In addition, compounds formed by adding protons to tertiary amines, secondary amines, and primary amines can also be used as bromine-containing compounds. If an example of a bromine-containing compound is cited, it is 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, benzylamine hydrobromide, etc. If an example of a phosphonium bromide is cited, it is tetramethylphosphonium bromide, tetraethylphosphonium bromide, tetrapropylphosphonium bromide, tetrabutylphosphonium bromide, tetraphenylphosphonium bromide, methyltriphenylphosphonium bromide, phenyltrimethylphosphonium bromide, methoxycarbonylmethyl(triphenyl)phosphonium bromide, etc. Trialkylammonium bromides are bromine salts containing sulfonium ions that can stably exist in the treatment liquid. If an example of a tertiary sulfonium bromide is cited, it is trimethylsulfonium bromide, triethylsulfonium bromide, tripropylsulfonium bromide, tributylsulfonium bromide, triphenylsulfonium bromide, (2-carboxyethyl)dimethylsulfonium bromide, etc. Among them, from the viewpoints of high stability, being easily obtainable in high purity industrially, and being inexpensive, bromine salts containing ammonium ions, i.e., tetraalkylammonium bromides, are preferred.

[0122] The above-mentioned tetraalkylammonium bromides are preferably tetraalkylammonium bromides with particularly excellent stability and easy synthesis.

[0123] 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 a tetraalkylammonium bromide, a tetraalkylammonium bromide having 1 to 20 carbon atoms in each alkyl group can be preferably used. Among them, from the viewpoint of having a large number of bromine atoms per unit weight, a tetraalkylammonium bromide having a small number of carbon atoms in the alkyl group can be further preferably used. If an example is cited, it is tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetraamylammonium bromide, tetrahexylammonium bromide, etc. Among them, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide are preferred, and tetraethylammonium bromide is most preferred. The bromine-containing compound contained in the treatment liquid may be one kind or a plurality of kinds.

[0124] The tetraalkylammonium bromide used in the present invention may be a commercially available tetraalkylammonium bromide, or a tetraalkylammonium bromide produced from a tetraalkylammonium ion and a bromide ion. As a method for producing tetraalkylammonium bromide, an aqueous solution containing tetraalkylammonium hydroxide is mixed with an aqueous solution containing bromide ions, or a bromine-containing gas such as hydrogen bromide that generates bromide ions when dissolved in water.

[0125] Examples of the tetraalkylammonium hydroxide used for producing tetraalkylammonium bromide include: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Among them, from the viewpoint of having a large number of hydroxide ions per unit weight and being able to easily obtain a high-purity product, tetramethylammonium hydroxide is more preferred.

[0126] Examples of the bromide ion source that generates bromide ions for producing tetraalkylammonium bromide include: hydrogen bromide, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, ammonium bromide, etc. Among them, from the viewpoint of being substantially free of metals, being easily available industrially, and being able to easily obtain a high-purity product, hydrogen bromide is preferred.

[0127] The addition amount of the bromine-containing compound is not particularly limited, and it can be determined in consideration of the etching rate of ruthenium, the stability of the treatment liquid, the solubility of the bromine-containing compound, the cost, etc. The bromine-containing compound added to the treatment liquid is oxidized by an oxidant described later to become a chemical substance effective for etching ruthenium. Specifically, it is bromine (Br 2 ), hypobromous acid (HBrO), hypobromite ion (BrO － ), bromous acid (HBrO 2 ), bromite ion (BrO 2 － ), bromic acid (HBrO 3 ), bromate ion (BrO 3 － ), perbromic acid (HBrO 4 ), perbromate ion (BrO4 － ) and bromide ions (Br － ).

[0128] Among the chemical species effective for etching ruthenium described above, those containing HBrO, BrO － , HBrO 2 , BrO 2 － , HBrO 3 , BrO 3 － have a high etching rate of ruthenium, so the treatment liquid preferably contains these chemical species. Among them, a treatment liquid containing a large amount of HBrO and BrO － (hereinafter sometimes also referred to as BrO － etc.) has a particularly high etching rate of ruthenium, so it is further preferred in terms of shortening the treatment time.

[0129] Therefore, when oxidizing the bromine-containing compound with an oxidant, it is preferable to oxidize the bromine atoms contained in the bromine-containing compound to HBrO, BrO － , HBrO 2 , BrO 2 － , HBrO 3 , BrO 3 － , and among them, it is more preferable to oxidize to BrO － etc.

[0130] By increasing the proportion of BrO － etc. contained in the treatment liquid, the etching rate of ruthenium can be increased. Specifically, by preparing a treatment liquid in which the proportion of BrO － in 1 mole of bromine element contained in the treatment liquid exceeds 0.5 moles, ruthenium can be etched efficiently.

[0131] In the chemical species effective for etching ruthenium described above, namely Br 2 , HBrO, BrO － , HBrO 2 , BrO 2 － , HBrO 3 , BrO 3 － , HBrO 4 , BrO 4 － decomposition; when Br － is generated by reaction with ruthenium, it is preferable to include in the treatment liquid a substance that can convert Br －An oxidizing agent that is re-oxidized to a chemical species effective for etching ruthenium. If such an oxidizing agent is present in the treatment liquid, the concentration of the chemical species effective for etching ruthenium can be maintained at a high level, and the etching rate of ruthenium can be maintained. In the case where BrO － etc. decompose through disproportionation reactions, etc., sometimes HBrO 2 or BrO 2 － is produced via HBrO 3 or BrO 3 － and Br － . In the treatment liquid of the present invention, in addition to containing BrO － etc., it also contains one or more of HBrO 2 , BrO 2 － , HBrO 3 , BrO 3 － , Br － etc. In this case, it is a treatment liquid that can be preferably used for etching ruthenium. When the treatment liquid contains multiple chemical species effective for etching ruthenium, it is also preferable to contain an oxidizing agent in the treatment liquid that can re-oxidize Br － to a chemical species effective for etching ruthenium.

[0132] In addition, if in the treatment liquid, in addition to containing BrO － , it also contains decomposition products of BrO － (for example, HBrO 2 , BrO 2 － , HBrO 3 , BrO 3 － , Br － etc.), then the change in the concentration of BrO － in the treatment liquid slows down, and the etching rate of ruthenium becomes more stable. Therefore, in the treatment liquid of the present invention, one or more of the above decomposition products of BrO － can also be contained. For example, the treatment liquid of the present invention containing BrO － , BrO 3 － can be preferably used for etching ruthenium.

[0133] In order to efficiently etch ruthenium, the proportion of BrO － in 1 mole of bromine element contained in the treatment liquid is preferably more than 0.5 moles.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] When the above (A)Br － When the reaction of being oxidized by the oxidant to a chemical species effective for etching ruthenium proceeds, 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.

[0138] 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 is less than 0.5 with respect to 1 mole of bromine element contained in the treatment liquid.

[0139] In an acidic condition, a bromine-containing compound or Br － For the oxidation of a chemical substance effective for ruthenium etching, in the case of ruthenium etching under alkaline conditions, between the generation of a chemical substance effective for ruthenium etching using an oxidant and ruthenium etching, the time required for the generation of bromine gas and the time required for adjusting the pH of the treatment liquid are needed. Therefore, the ruthenium etching process becomes intermittent and the productivity deteriorates significantly. Therefore, it is necessary to generate a chemical substance effective for ruthenium etching using an oxidant only once under acidic conditions before ruthenium etching. In this case, the reactions of (A) and (B) above do not occur continuously repeatedly. Therefore, the ratio of BrO － in 1 mole of bromine element contained in the treatment liquid is 0.5 or less.

[0140] When ruthenium is etched using the above treatment liquid, the chemical substance effective for ruthenium etching is unidirectionally reduced due to the reaction with ruthenium. Therefore, the ratio of BrO － in 1 mole of bromine element contained in the treatment liquid is further less than 0.5.

[0141] In a treatment liquid in which the ratio of BrO － in 1 mole of bromine element contained in the treatment liquid is 0.5 mole or less, compared with a treatment liquid in which the ratio of BrO － in 1 mole of bromine element contained in the treatment liquid exceeds 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 liquid are significantly reduced. Therefore, in order to stably and efficiently perform ruthenium etching, it is preferable to make the treatment liquid alkaline and set the ratio of BrO － in 1 mole of bromine element contained in the treatment liquid to exceed 0.5 mole of the treatment liquid.

[0142] Regarding this bromine-containing compound, with respect to the total mass of the treatment liquid, the addition amount of the above bromine-containing compound is preferably 0.008 mass% or more and less than 10 mass% in terms of bromine element amount. When it is less than 0.008 mass%, the etching rate of ruthenium is slow and the practicality is low. When it is 10 mass% or more, it is difficult to control the ruthenium etching rate and it is difficult to control as a manufacturing process. Therefore, from the viewpoints of a large etching rate and controlling the etching rate for efficient manufacturing, the addition amount of the bromine-containing compound contained in the treatment liquid of the present invention is preferably 0.008 mass% or more and less than 10 mass% in terms of bromine element amount. In addition, the upper limit of the addition amount of the bromine-containing compound contained in the treatment liquid of the present invention is more preferably less than 2 mass% in terms of bromine element amount. If the addition amount of the bromine-containing compound is less than 2.0 mass%, it is not easy to cause a chemical substance effective for ruthenium etching, especially HBrO, BrO － 、HBrO2 , BrO 2 － The disproportionation reaction of 2 and 2 can suppress the concentration fluctuations 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% by mass, the RuO 4 gas concentration generated per unit time can be suppressed to a low level by controlling the etching rate of ruthenium, and the generation of RuO 2 particles can be further reduced.

[0143] In addition, the lower limit of the addition amount of the bromine-containing compound contained in the treatment liquid of the present invention is preferably 0.01% by mass or more in terms of the amount of bromine element. If the addition amount of the bromine-containing compound is 0.01% by mass or more, chemical species effective for etching ruthenium can be efficiently generated, the etching rate is further increased, and ruthenium can be etched efficiently at a stable etching rate. Therefore, the addition amount of the bromine-containing compound contained in the treatment liquid of the present invention is further preferably 0.01% by mass or more and less than 2% by mass in terms of the amount of bromine element. In addition, from the viewpoint of improving throughput and production efficiency, the addition amount of the bromine-containing compound is further preferably 0.04% by mass or more and less than 2.0% by mass in terms of the amount of bromine element. Moreover, from the viewpoint that re-oxidation of chemical species effective for etching ruthenium by an oxidizing agent easily occurs and the etching rate becomes more stable, the addition amount of the bromine-containing compound is most preferably 0.08% by mass or more and less than 2.0% by mass in terms of the amount of bromine element.

[0144] The pH of the solution containing the bromine-containing compound is not particularly limited, and is preferably 8 or more and 14 or less, more preferably 12 or more and 13 or less. If the solution is in this pH range, the pH decrease generated when the solution containing an oxidizing agent described later is mixed with the solution containing the bromine-containing compound 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 less than 8, when the solution containing an oxidizing agent described later is mixed with the solution containing the bromine-containing compound, the pH and liquid volume of the solution containing the bromine-containing compound may be adjusted so that the pH of the mixed treatment liquid becomes alkaline.

[0145] An iodine-containing compound can also be used in the same manner as the bromine-containing compound. In this case, iodine contained in the iodine-containing compound can be oxidized by an oxidizing agent contained in the treatment liquid to become chemical species for etching ruthenium.

[0146] (Oxidizing agent)

[0147] The oxidizing agent used in the treatment liquid of the present invention has the following functions: it can oxidize bromine-containing compounds to generate chemical substances effective for ruthenium etching. Specifically, examples include: nitric acid, sulfuric acid, persulfuric acid, peroxydisulfuric acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, periodic acid, their salts, and ions generated by dissociation of their salts. Further, examples include: hydrogen peroxide, ozone, fluorine, chlorine, bromine, iodine, permanganate, chromate, dichromate, cerium salt, etc. These oxidizing agents can be used alone or in combination of multiple kinds. When adding these oxidizing agents to the treatment liquid of the present invention, any appropriate form of solid, liquid, or gas can be selected according to the properties of the oxidizing agent used.

[0148] Among the above-mentioned oxidizing agents, from the viewpoint of being able to stably exist even under alkaline conditions, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, periodic acid, their salts, ions generated by dissociation of their salts, ozone or hydrogen peroxide are preferred, more preferably hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, their salts, ions generated by dissociation of their salts, ozone or hydrogen peroxide, further preferably hypochlorite ion or ozone, and most preferably hypochlorite ion.

[0149] If hypochlorous acid, tetraalkylammonium hypochlorite as its salt, or ozone is used as the oxidizing agent, metal contamination can be substantially prevented, so it is preferably used as a treatment liquid for semiconductor manufacturing. Among them, from the viewpoints of being stable in alkali and being able to efficiently oxidize the above-mentioned bromine-containing compounds, tetraalkylammonium hypochlorite is particularly preferred.

[0150] The concentration of this oxidizing agent is not particularly limited, as long as an amount that can oxidize the bromine-containing compound to a chemical substance effective for ruthenium etching is added.

[0151] The addition amount of the above-mentioned oxidizing agent is preferably 0.1 mass ppm or more and 10 mass% or less. If the addition amount of this oxidizing agent is less than 0.1 mass ppm, the bromine-containing compound cannot be efficiently oxidized, and the etching rate of ruthenium decreases. That is, in the composition without mixing this oxidizing agent, the etching rate is low. On the other hand, if the addition amount of this oxidizing agent is greater than 10 mass%, the stability of this oxidizing agent decreases, so it is not suitable. From the viewpoints of taking into account gas inhibition and the etching rate of ruthenium, the concentration of the oxidizing agent 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 in the case where the oxidizing agent is ozone, it is preferably within the above concentration range. 4 From the viewpoints of taking into account gas inhibition and the etching rate of ruthenium, the concentration of the oxidizing agent 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 in the case where the oxidizing agent is ozone, it is preferably within the above concentration range.

[0152] The pH of the solution containing the oxidizing agent is not particularly limited, preferably 8 or more and 14 or less, more preferably 12 or more and 13 or less. If the solution is in this pH range, the decrease in pH generated when the solution containing the bromine-containing compound and the solution containing the oxidizing agent 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 oxidizing agent is less than 8, when the solution containing the bromine-containing compound and the solution containing the oxidizing agent are mixed, the pH and liquid volume of the solution containing the oxidizing agent can be adjusted so that the pH of the mixed treatment liquid becomes alkaline.

[0153] <Manufacturing method of tetraalkylammonium hypochlorite solution>

[0154] As described above, as the oxidizing agent optionally contained in the treatment liquid of the present invention, tetraalkylammonium hypochlorite is preferred. Therefore, hereinafter, preferred embodiments of the manufacturing method of tetraalkylammonium hypochlorite will be described. The manufacturing method of this oxidizing agent includes: a preparation step of preparing a tetraalkylammonium hydroxide solution; and a reaction step of bringing the tetraalkylammonium hydroxide solution into contact with chlorine.

[0155] (Preparation step of preparing a tetraalkylammonium hydroxide solution)

[0156] In the tetraalkylammonium hydroxide solution, carbon dioxide derived from the atmosphere is usually contained. Carbon dioxide exists in the solution in the form of carbonate ions or bicarbonate ions. The carbon dioxide concentration is not particularly limited, and in terms of carbonate ions, it is preferably 0.001 ppm or more and 500 ppm or less (mass basis), more preferably 0.005 ppm or more and 300 ppm or less, and further preferably 0.01 ppm or more and 100 ppm or less. By the carbon dioxide concentration in the tetraalkylammonium hydroxide solution being 0.001 ppm or more and 500 ppm or less, the pH change of the obtained tetraalkylammonium hypochlorite solution can be suppressed. As a result, the storage stability of this tetraalkylammonium hypochlorite solution can be improved.

[0157] In the present embodiment, the tetraalkylammonium hydroxide solution is preferably a solution of tetraalkylammonium hydroxide having 1 to 10 carbon atoms in the alkyl group, more preferably a solution of tetraalkylammonium hydroxide having 1 to 5 carbon atoms. If specific tetraalkylammonium hydroxides are exemplified, they are tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, etc. These tetraalkylammonium hydroxides can be used alone or in combination of two or more. In addition, the carbon atom numbers of the four alkyl groups contained in the tetraalkylammonium hydroxide can be the same or different.

[0158] (Reaction step of bringing the tetraalkylammonium hydroxide solution into contact with chlorine)

[0159] By bringing a tetraalkylammonium hydroxide solution into contact with chlorine and reacting, the hydroxide ions of the tetraalkylammonium hydroxide are replaced by hypochlorite ions generated from chlorine, and a tetraalkylammonium hypochlorite solution is produced.

[0160] In the present embodiment, the upper limit of the carbon dioxide concentration in the gas phase portion is 100 volume ppm. However, 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, and a tetraalkylammonium hypochlorite solution with excellent storage stability can be manufactured.

[0161] The pH range of the liquid phase portion in the reaction step of the present embodiment is 10.5 or more. The upper limit is not particularly limited. If the pH during the reaction is excessively high, when stored at the same pH as after the reaction for a long period of time, the hypochlorite ions may decompose and the available chlorine concentration may decrease. Therefore, the pH of the liquid phase portion in the reaction step is preferably less than 14, more preferably less than 13.9, and further preferably 11 or more and less than 13.8. If the pH is within the above range, the decomposition of hypochlorite ions is suppressed during the storage of the obtained tetraalkylammonium hypochlorite solution, and the storage stability is improved.

[0162] In the reaction step of the present embodiment, the reaction temperature range of the tetraalkylammonium hydroxide solution is preferably -35°C or higher and 25°C or lower, more preferably -15°C or higher and 25°C or lower, and further preferably 0°C or higher and 25°C or lower. If the reaction temperature is within the above range, the tetraalkylammonium hydroxide solution reacts sufficiently with chlorine, and a tetraalkylammonium hypochlorite solution can be obtained with high production efficiency.

[0163] It can be clarified therefrom that the tetraalkylammonium hypochlorite solution obtained by the manufacturing method of the present embodiment has excellent storage stability and can preferably be used as the oxidizing agent contained in the treatment liquid of the present invention.

[0164] (Base compound)

[0165] There is no particular limitation on the base compound used in the treatment liquid 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, tetraalkylammonium hydroxide, etc. can be used. Among these base compounds, sodium hydroxide, potassium hydroxide, ammonia, choline, and tetraalkylammonium hydroxide are easily available and can achieve a high ruthenium etching rate when used in the treatment liquid, so they are preferred. Ammonia, choline, and tetraalkylammonium hydroxide do not contain metals, so they can be particularly preferably used as the treatment liquid of the present invention. As tetraalkylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. can be industrially obtained, and tetramethylammonium hydroxide is most preferred in terms of being able to easily obtain a high-purity semiconductor manufacturing grade. The above base compounds can be added to the treatment liquid in the form of a solid or an aqueous solution.

[0166] The concentration of the above-mentioned alkali compound is not particularly limited as long as it does not deviate from the object of the present invention. The pH of the solution containing the alkali compound is preferably in the range of pH 8 or more and 14 or less, more preferably 12 or more and 13 or less. If the pH of the solution containing the alkali compound is within this pH range, the decrease in pH generated when the solution containing the above-mentioned oxidant is mixed with the solution containing the bromine-containing compound can be reduced, and the treatment liquid of the present invention can be stably manufactured, stored, and used.

[0167] (Water)

[0168] 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 well-known methods widely used in semiconductor manufacturing.

[0169] (pH)

[0170] The pH of the treatment liquid of the present invention is preferably 8 or more and 14 or less. If the pH of the treatment liquid is within this range, ruthenium can be etched at a sufficient rate, and RuO 4 gas generation can be suppressed. When the pH of the treatment liquid is lower than 8, the generation of RuO 2 particles becomes significant, and the yield of semiconductor elements deteriorates. On the other hand, when the pH of the treatment liquid exceeds 14, the above-mentioned oxidant decomposes, so the oxidation of the bromine-containing compound may be inconsistent. This means that the etching rate of ruthenium is not constant, which will complicate the process control in the semiconductor manufacturing process, so it needs to be avoided.

[0171] The higher the pH of the treatment liquid, the less the amount of RuO 4 gas generated along with the etching of ruthenium. On the other hand, the higher the pH of the treatment liquid, the lower the etching rate of ruthenium. Therefore, from the viewpoint of achieving both RuO 4 gas suppression and etching rate, the pH of the treatment liquid is preferably 12 or more and 14 or less, more preferably 12 or more and less than 13. If the pH of the treatment liquid is within the above range, the chemical substances effective for etching ruthenium contained in the treatment liquid of the present invention can dissolve ruthenium at a sufficient etching rate and suppress RuO 4 gas generation.

[0172] The pH during the etching of ruthenium metal is preferably 11 or more and 14 or less, more preferably 12 or more and less than 13. If the pH of the treatment liquid is within this range, during the etching of ruthenium metal, the etching rate and the amount of RuO 4 gas generation can be reduced.

[0173] When etching the ruthenium alloy, the pH is preferably 12 or more and 14 or less, more preferably 12 or more and less than 13.

[0174] (Method for manufacturing the treatment liquid)

[0175] When the treatment liquid of the present invention contains a bromine-containing compound, an oxidizing agent, an alkali compound, and water, the treatment liquid can be a single liquid, or a solution of two liquids or more than two liquids. When the treatment liquid is a single liquid, it becomes a solution containing all the bromine-containing compound, oxidizing agent, alkali compound, and water. When the treatment liquid is two liquids or more than two liquids, the treatment liquid can be manufactured by mixing the respective liquids. In addition, when the treatment liquid is two liquids or more than two liquids, each liquid contains at least one or more of a bromine-containing compound, an oxidizing agent, an alkali compound, and water. Other components described later may also be further contained. Even when the treatment liquid is any one of a single liquid and two or more liquids, a bromine-containing compound is oxidized by an oxidizing agent in the treatment liquid to generate chemical species effective for etching ruthenium.

[0176] When the treatment liquid is made into a plurality of types, it is preferable to separate the treatment liquid containing the bromine-containing compound from the treatment liquid containing the oxidizing agent. By separating the bromine-containing compound and the oxidizing agent, oxidation of the bromine-containing compound by the oxidizing agent can be prevented, and the treatment liquid of the present invention can be stably stored.

[0177] As the mixing method of the treatment liquid, a method widely known as a mixing method for semiconductor chemical liquids can be used. For example, a method using a mixing tank, a method of mixing in a pipe of a semiconductor manufacturing apparatus (inline mixing), a method of mixing by simultaneously pouring a plurality of liquids onto a wafer, etc. can be preferably used.

[0178] In the case of manufacturing a treatment liquid by mixing multiple types of treatment liquids, the mixing of the treatment liquids can be carried out at any time. When the oxidation of the bromine-containing compound takes time, by mixing the treatment liquid before etching ruthenium, the time for generating chemical species effective for ruthenium etching can be set. In this case, if the oxidation of the bromine-containing compound takes time, it becomes a bottleneck in the manufacturing line, and thus sometimes leads to a reduction in production. For this reason, it is preferable that the time required for oxidation is short, preferably 1 hour or less. The time required for oxidation of the bromine-containing compound can be controlled by appropriately selecting the oxidant concentration, the bromine-containing compound concentration, the pH of the treatment liquid, the temperature of the treatment liquid, the stirring method of the treatment liquid, etc. For example, when oxidizing a bromine-containing compound with an oxidant to generate hypobromite ions, from the viewpoint of reaction kinetics, by increasing the concentration of the reactants, 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 only the concentration of either one can be increased. In addition, by increasing the temperature of the treatment liquid at the time of mixing, the time required for oxidation of the bromine-containing compound can also be shortened.

[0179] In addition, when the concentration of chemical species effective for ruthenium etching is low, it is considered that the service life of the treatment liquid is short and the control of the manufacturing process becomes difficult. In such a case, it is preferable to perform mixing immediately before ruthenium etching.

[0180] Therefore, in the case of mixing multiple treatment liquids, it is preferable to mix a solution containing an oxidant and an alkali compound with a solution containing a bromine-containing compound, and more preferably to mix a solution containing hypochlorite ions and an alkali compound with a solution containing a bromine-containing compound. The solution containing the above hypochlorite ions and an alkali compound is preferably alkaline. In addition, the mixing preferably involves adding the 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 and thus toxic chlorine gas may be generated. The solution containing the oxidant and the alkali compound and the solution containing the bromine-containing compound can both be solutions or both be 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 thus the oxidant decomposes. For this reason, the solution is preferably an aqueous solution.

[0181] In the mixing of the treatment liquid of the present invention, the pH of the mixed treatment liquid is preferably alkaline. Specifically, the pH of the treatment liquid is preferably 8 or more and 14 or less. When the pH of the treatment liquid before mixing is less than 8, the concentration of the alkali compound and / or water is adjusted so that the mixed treatment liquid (including the bromine-containing compound, the oxidizing agent, the alkali compound, and water) has a pH of 8 or more and 14 or less. Thus, by maintaining the pH of the mixed treatment liquid at 8 or more and 14 or less, the bromine-containing compound can be rapidly changed into chemical species effective for ruthenium etching by the oxidizing agent, and the ruthenium film can be etched at a stable and sufficient rate.

[0182] When mixing a plurality of treatment liquids to generate chemical species effective for ruthenium etching, the pH of the mixed treatment liquids may be the same or different. When the pH of the treatment liquids is the same, the pH of the mixed treatment liquid does not change significantly, and it can preferably be used as an etching liquid for ruthenium.

[0183] When mixing a plurality of treatment liquids to generate chemical species effective for ruthenium etching, as long as the composition after mixing (bromine-containing compound concentration, oxidizing agent concentration, alkaline compound concentration, pH) is within the above ranges, there are no particular limitations on the mixing method such as the mixing ratio and mixing order of the mixed treatment liquids. However, for example, when mixing an alkaline solution containing a hypochlorite compound with an acidic solution containing a bromine-containing compound, the decomposition of the hypochlorite compound may occur locally. Therefore, in this case, it is preferable to mix the acidic solution containing the bromine-containing compound into the alkaline solution containing the hypochlorite compound.

[0184] In the present invention, the hypochlorite compound refers to a compound that generates hypochlorous acid or hypochlorite ions in the treatment liquid. If an example of the hypochlorite compound is listed, it can be listed as: hypochlorous acid, hypochlorites, hydantoins, isocyanuric acids, sulfamic acids, chloramines, etc. Among them, from the viewpoint of efficiently generating hypochlorous acid or hypochlorite ions, hypochlorous acid and hypochlorites are preferred. As the hypochlorous acid, tetraalkylammonium hypochlorite is preferred, and among them, from the viewpoint of a large amount of hypochlorous acid or hypochlorite ions per unit weight, tetramethylammonium hypochlorite is more preferred.

[0185] The chemical species effective for ruthenium etching generated by oxidizing the bromine-containing compound with an oxidizing agent vary depending on the pH, oxidation-reduction potential (ORP), etc. of the treatment liquid, but are mainly bromine or bromide ions, hypobromous acid, bromous acid, bromic acid, perbromic acid, and their ions.

[0186] In addition, in the treatment liquid of the present invention, metals are preferably contained, specifically, the contents of sodium, potassium, aluminum, magnesium, iron, nickel, copper, silver, cadmium, and lead are each 1 ppb or less.

[0187] In the treatment liquid of the present invention, the ammonia and amines contained in the bromine-containing compound, oxidizing agent, alkali compound, water, solvent, and other additives used in the treatment liquid are preferably less. The reason is that if ammonia and amines are present in the treatment liquid, they will react with the oxidizing agent, bromine-containing compound, and chemical substances effective for ruthenium etching generated from the bromine-containing compound, etc., which will reduce the stability of the treatment liquid. For example, when tetramethylammonium hydroxide is used in the alkali compound, the ammonia and amines contained in this alkali compound, especially trimethylamine, sometimes cause the reduction of the 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 this alkali compound is preferably 100 ppm or less. If the total amount of amines is 100 ppm or less, the influence caused by the reaction with the oxidizing agent, bromine-containing compound, and chemical substances effective for ruthenium etching generated from the bromine-containing compound is slight, and the stability of the treatment liquid is not impaired.

[0188] When manufacturing the treatment liquid of the present invention, in order to prevent the decomposition of the oxidizing agent, chemical substances effective for ruthenium etching generated from the bromine-containing compound, etc. caused by light, it is preferably carried out under light shielding.

[0189] In addition, in the manufacture of the treatment liquid of the present invention, it is preferable to prevent the dissolution of carbon dioxide in the treatment liquid. When the treatment liquid of the present invention is alkaline, carbon dioxide is easily dissolved in the treatment liquid, which may cause a change in pH. If the pH of the treatment liquid changes, it will not only cause a change in the etching rate of ruthenium, but also reduce the stability of the treatment liquid. The dissolution of carbon dioxide in the treatment liquid can be reduced by the following methods: flowing an inert gas to purge carbon dioxide in the manufacturing apparatus, reacting in an inert gas atmosphere, etc. If the carbon dioxide in the manufacturing apparatus is 100 ppm or less, the influence caused by the dissolution of carbon dioxide can be ignored.

[0190] In the production of the treatment liquid of the present invention, the surface in contact with the treatment liquid of the reaction vessel is preferably formed of glass or an organic polymer material. The reason is that if the inner surface of the reaction vessel is formed of glass or an organic polymer material, the mixing of impurities such as metals, metal oxides, and organic substances can be further reduced. As the organic polymer material for the inner surface of the reaction vessel, vinyl chloride resins (soft / hard vinyl chloride resins), nylon resins, silicone resins, polyolefin resins (polyethylene, polypropylene), fluorine resins, etc. can be used. Among them, considering the ease of molding, solvent resistance, and less dissolution and precipitation of impurities, fluorine resins are preferred. As the fluororesin, as long as it is a resin (polymer) containing fluorine atoms, there is no particular limitation, and known fluororesins can be used. For example, polytetrafluoroethylene, poly(chlorotrifluoroethylene), poly(vinylidene fluoride), tetrafluoroethylene - hexafluoropropylene copolymer, tetrafluoroethylene - perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene - ethylene copolymer, chlorotrifluoroethylene - ethylene copolymer, and cyclized polymers of perfluoro(butenyl vinyl ether) can be cited.

[0191] (Other additives)

[0192] In the treatment liquid of the present invention, other additives conventionally used in treatment liquids for semiconductors can also be incorporated within the scope that does not impair the object of the present invention as desired. For example, as other additives, acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidants, reductants, complexing agents, chelating agents, surfactants, defoaming agents, pH adjusters, stabilizers, etc. can be added. These additives can be added individually or in combination of multiple kinds.

[0193] In addition to these additives, depending on the circumstances in the production of the treatment liquid, etc., the treatment liquid of the present invention may also contain alkali metal ions, alkaline earth metal ions, etc. For example, sodium ions, potassium ions, calcium ions, etc. may also be contained. However, when these alkali metal ions and alkaline earth metal ions remain on the semiconductor wafer, they will have an adverse effect on the semiconductor element (such as a reduction in the yield of the semiconductor wafer), so it is preferred that the amounts of these alkali metal ions and alkaline earth metal ions are small and actually infinitely close to not containing 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 hydroxide are preferred.

[0194] Specifically, regarding alkali metal ions and alkaline earth metal ions, their total amount is preferably 1% by mass or less, more preferably 0.7% by mass or less, further preferably 0.3% by mass or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0195] The treatment liquid of the present invention may further contain an organic solvent. The treatment liquid of the present invention containing an organic solvent can inhibit the generation of RuO 4 gas. Any organic solvent can be used as long as it does not impair the function of the treatment liquid of the present invention. If an example is cited, it is sulfolane, acetonitrile, carbon tetrachloride, 1,4-dioxane, etc. Of course, the organic solvent is not limited to these.

[0196] When etching ruthenium with the treatment liquid of the present invention, the temperature is not particularly limited and can be determined by considering the etching rate of ruthenium, the stability of the treatment liquid, the amount of RuO 4 gas generation, etc. The higher the treatment temperature, the more the amount of RuO 4 gas generated, so it is preferred to have a low treatment temperature. On the other hand, the higher the temperature, the greater the etching rate of ruthenium. From the perspective of balancing RuO 4 gas inhibition 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.

[0197] When etching ruthenium with the treatment liquid of the present invention, the treatment time is 0.1 to 120 minutes, preferably in the range of 0.3 to 60 minutes, and can be appropriately selected according to the etching conditions and the semiconductor element used. As the rinsing liquid after using the treatment liquid of the present invention, an organic solvent such as alcohol can be used, but rinsing only with deionized water is also sufficient.

[0198] If the treatment liquid of the present invention is used, the generation of RuO 4 gas can be inhibited, and ruthenium attached to the end face and back face of the semiconductor wafer can be removed at a sufficient etching rate ( or more). In the case where an etching rate of or more is required, the following conditions can be appropriately selected: the concentration of hypobromite ions, the concentration of hypochlorite ions, the concentration of bromine-containing compounds, the concentration of oxidants, the pH of the treatment liquid, the treatment temperature, the contact method between the treatment liquid and the wafer, etc.

[0199] After the treatment liquid of the present invention is manufactured, the ruthenium-based metal film and / or ruthenium alloy film deposited on the substrate can be etched with the treatment liquid.

[0200] (Storage of the treatment liquid)

[0201] The treatment liquid of the present invention is preferably stored at low temperature and / or in the dark. By storing it at low temperature and / or in the dark, an effect of suppressing the decomposition of oxidants, hypobromite ions, etc. in the treatment liquid can be expected. Moreover, by storing the treatment liquid in a container filled with an inert gas to prevent the mixing of carbon dioxide, the stability of the treatment liquid can be maintained. In addition, the inner surface of the container, i.e., the surface in contact with the treatment liquid, 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 mixing of impurities such as metals, metal oxides, and organic substances can be further reduced. As the organic polymer material for the inner surface of the reaction container, the materials exemplified in the production of the treatment liquid of the present invention can be preferably used. In addition, the pH during the storage of the treatment liquid 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 liquid is preferably alkaline, more preferably 8 or more and 14 or less, and most preferably 12 or more and 14 or less.

[0202] [Examples]

[0203] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

[0204] (pH measurement method)

[0205] Using a bench-top pH meter (LAQUA F-73, manufactured by Horiba, Ltd.), the pH of 10 mL of the treatment liquid prepared in the examples and comparative examples was measured. The pH measurement was carried out after the treatment liquid was prepared and stabilized at 25°C.

[0206] (Ru film formation and film thickness change amount)

[0207] The Ru films used in the examples and comparative examples were formed as follows. An oxide film was formed on a silicon wafer using a batch-type thermal oxidation furnace, and Ru was formed on the oxide film using sputtering (±10%). The sheet resistance was measured by a four-probe resistance measuring instrument (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted into a film thickness, which was used as the Ru film thickness before the etching treatment. Similarly, after the etching treatment, the sheet resistance was measured by a four-probe resistance measuring instrument and converted into a film thickness, which was used as the Ru film thickness after the etching treatment. The difference between the Ru film thickness after the etching treatment and the Ru film thickness before the etching treatment was used as the film thickness change amount before and after the etching treatment.

[0208] (RuO₂ film formation and film thickness change amount)

[0209] The RuO₂ film used in the examples was formed as follows. An oxide film was formed on a silicon wafer using a batch-type thermal oxidation furnace, and RuO₂ was formed on the oxide film using sputtering (±10%). 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 dioxide film thickness before the etching treatment. Similarly, after the etching treatment, the sheet resistance was measured by a four-probe resistance measuring instrument and converted into film thickness, which was used as the ruthenium dioxide film thickness after the etching treatment. The difference between the ruthenium dioxide film thickness after the etching treatment and the ruthenium dioxide film thickness before the etching treatment was used as the film thickness change amount before and after the etching treatment.

[0210] (Calculation method of etching rate of ruthenium or ruthenium dioxide)

[0211] 60 mL of the treatment liquids of the examples and comparative examples were prepared in a covered fluororesin container (manufactured by AsOne, PFA container 94.0 mL). Each sample piece measuring 10×20 mm was immersed in the treatment liquid at 25 °C for 1 minute to perform the etching treatment of ruthenium or ruthenium dioxide.

[0212] In addition, 60 mL of the treatment liquid was prepared in a covered fluororesin container and immersed in a water bath heated to 60 °C (manufactured by ThermoFisher Scientific, Isotemp general covered water bath) for 1 hour to set the temperature of the treatment liquid to 60 °C. Each sample piece measuring 10×20 mm was immersed in the treatment liquid at 60 °C for 1 minute to perform the etching treatment of ruthenium or ruthenium dioxide.

[0213] The value obtained by dividing the film thickness change amount before and after the etching treatment by the immersion time was calculated as the etching rate and 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 amount before and after the treatment was less than 5 Å, it was considered as not etched.

[0214] (RuO 4 Gas quantitative analysis)

[0215] RuO 4 The amount of RuO gas generated was measured by ICP-OES. 5 mL of the treatment liquid was taken into a closed container, and a 10×20 mm Si wafer with a ruthenium film of a certain film thickness was immersed therein at 25 °C or 60 °C until all the ruthenium was dissolved. Then, air was allowed to flow in the closed container, and the gas phase in the closed container was bubbled into a container containing an absorbent liquid (1 mol / L NaOH) to trap the RuO gas generated during the immersion into the absorbent liquid. The amount of ruthenium in this absorbent liquid was measured by ICP-OES to obtain the amount of RuO generated. 4 4Amount of Ru in the gas. It was confirmed that all the ruthenium on the Si wafer impregnated in the treatment liquid was dissolved by measuring the sheet resistance before and after impregnation with a four-probe resistance measuring device (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converting it to the film thickness. Using RuO 4 The value obtained by dividing the weight of Ru contained in the gas absorption liquid by the area of the Ru-bearing wafer was used to evaluate the RuO 4 gas generation amount. Regarding RuO 4 When the gas generation amount was 40 μg / cm 2 or less, it was regarded that the RuO 4 gas generation was suppressed.

[0216] 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 manufacturing conditions of the oxidizing agent are shown in Table 7, and the redox potentials (calculated values) of the hypochlorite ion (ClO － ) / Cl － system and the hypobromite ion (BrO － ) / Br － system at 25 °C are shown in Table 8, and the preparation conditions of the aqueous solution of tetraethylammonium bromide are shown in Table 9.

[0217] (Calculation method for hypobromite ion and hypochlorite ion concentrations)

[0218] The concentrations of hypobromite ion and hypochlorite ion were measured using an ultraviolet-visible spectrophotometer (UV-2600, manufactured by Shimadzu Corporation). A calibration curve was made using aqueous solutions of hypobromite ion and hypochlorite ion with known concentrations, and the concentrations of hypobromite ion and hypochlorite ion in the produced treatment liquid were determined. The hypobromite ion concentration was obtained from the measurement data when the absorption spectrum was stable after mixing a bromine-containing compound, an oxidizing agent, and an alkali compound.

[0219] <Example 1>

[0220] (Preparation of samples to be etched)

[0221] A ruthenium film was formed by the method described in (film formation of ruthenium and change amount of film thickness), and a sample piece cut into 10×20 mm was used for evaluation.

[0222] (Manufacture of oxidizing agent)

[0223] 209 g of a 25% by mass aqueous solution of tetraethylammonium hydroxide and 791 g of ultrapure water were mixed in a 2-L glass three-necked flask (manufactured by COSMOSVID Co., Ltd.) to obtain a CO 2 content of 0.5 ppm and a 5.2% by mass aqueous solution of tetraethylammonium hydroxide. The pH at this time was 13.8.

[0224] Next, place a magnetic stir bar (manufactured by AsOne, total length 30 mm × diameter 8 mm) in a three-necked flask. Insert a thermometer protection tube (manufactured by COSMOSVID, bottom-sealed type) and a thermometer into one opening, connect a chlorine gas cylinder (bombe) and a nitrogen gas cylinder to the other opening, and immerse the tip of a PFA tube (manufactured by FLON Industries Co., Ltd., F-8011-02) that can arbitrarily switch between chlorine / nitrogen into the bottom of the solution. Connect a gas scrubber filled with a 5 mass% aqueous sodium hydroxide solution (manufactured by AsOne, gas scrubber, model 2450 / 500) to the remaining opening. Then, pass nitrogen gas with a carbon dioxide concentration of less than 1 ppm at 0.289 Pa·m 3 / s (at 0 °C conversion) through the PFA tube for 20 minutes to remove carbon dioxide from the gas phase. At this time, the carbon dioxide concentration in the gas phase is 1 ppm or less.

[0225] Then, place a magnetic stirrer (manufactured by AsOne, C-MAG HS10) under the three-necked flask, rotate and stir at 300 rpm, cool the outer periphery of the three-necked flask with ice water, and supply chlorine gas (manufactured by Fujiox, specification purity 99.4%) at 0.059 Pa·m 3 / s (at 0 °C conversion) for 180 minutes to obtain an aqueous solution of ammonium tetramethylhypochlorite (oxidizing agent; equivalent to 3.51 mass%, 0.28 mol / L) and a mixed solution of tetramethylammonium hydroxide (equivalent to 0.09 mass%, 0.0097 mol / L). At this time, the liquid temperature during the reaction is 11 °C.

[0226] (Manufacture of treatment liquid)

[0227] Add 0.79 g (equivalent to 0.77 mass%, 0.05 mol / L, 0.40 mass% in terms of bromine element amount) of 97 mass% ammonium tetramethyl bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) to 99.21 g of the mixed solution of ammonium tetramethylhypochlorite and tetramethylammonium hydroxide obtained by the above operation to obtain 100 g of the treatment liquid with the composition described in Tables 1 to 4. Here, the water described in Table 3 refers to water containing tetramethylammonium chloride when the oxidizing agent is ammonium tetramethylhypochlorite.

[0228] (Evaluation)

[0229] Evaluate the pH, ruthenium etching rate, RuO 4 gas generation amount, and hypobromite ion concentration of the treatment liquid just after manufacture. The evaluation of the ruthenium etching rate is carried out by the above "Calculation method of ruthenium etching rate". RuO 4 The evaluation of the gas generation amount is carried out by the above "RuO4 Quantitative analysis of the gas” was carried out. The evaluation of the hypobromite ion concentration was carried out by the above-mentioned “Calculation method of hypobromite ion concentration”. The evaluation of the stability of the etching rate was carried out as described below. Every 10 hours, the etching rate of the prepared treatment liquid was evaluated by the above-mentioned “Calculation method of ruthenium etching rate”. The time when the obtained etching rate increased or decreased within ±20% of the etching rate just after production was defined as the stable time of the etching rate.

[0230] <Examples 2 to 23, Comparative Examples 1 to 3>

[0231] In Examples 2 to 23 and Comparative Examples 1 to 3, treatment liquids were prepared by the same method as in Example 1 such that the concentrations of bromine-containing compounds, oxidizing agents, alkali compounds, and pH were as shown in Tables 1 to 4, and evaluations were performed using ruthenium films (sample pieces) prepared in the same manner as in Example 1. It should be noted that the change in film thickness before and after treatment in Comparative Examples 1 and 2 was less than 5 Å, so it was determined that Ru was not etched. Therefore, the evaluation of RuO 4 gas was not performed. In Examples 19 and 22, hydrobromic acid (acidic) was used as the bromine-containing compound, and after mixing with an aqueous solution (alkaline) containing an oxidizing agent and an alkali compound to adjust the aqueous solution (alkaline) containing hypobromite ions, ruthenium etching was carried out. Similarly in other examples, it was confirmed that the ruthenium etching rate was high, the stability of the etching rate was excellent, and the RuO 4 gas inhibition effect was high.

[0232] <Example 24>

[0233] (Preparation of solution containing oxidizing agent and alkali compound)

[0234] A solution (solution A) containing an oxidizing agent and an alkali compound was prepared by the method for manufacturing an oxidizing agent described in Example 1 such that the concentration of the oxidizing agent, the concentration of the alkali compound, and the pH were as shown in Table 6.

[0235] (Preparation of solution containing bromine-containing compound)

[0236] 3.97 g (equivalent to 3.85% by mass, 0.25 mol / L) of 97% by mass of tetramethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.354 g of 25% by mass of aqueous tetramethylammonium hydroxide solution, and 95.6 g of ultrapure water were mixed to prepare a solution (solution B) containing a bromine-containing compound such that the composition was as shown in Table 6.

[0237] (Manufacture of treatment liquid)

[0238] 20 g of solution B was added to 80 g of solution A obtained by the above operations to obtain 100 g of a treatment liquid having the composition described in Tables 1 to 4.

[0239] (Evaluation)

[0240] The obtained treatment liquid was evaluated by the same method as in Example 1.

[0241] <Examples 25 to 30>

[0242] In Examples 25 to 30, the treatment liquid was prepared by the same method as in Example 24 in such a manner that the concentrations of bromine-containing compounds, oxidizing agents, alkali compounds, and pH became the compositions shown in Tables 1 to 4, according to the compositions, mixing ratios, and mixing methods shown in Table 6, and evaluated. The reaction time in Table 6 refers to the time from the mixing of Liquid A and Liquid B until the etching rate is stabilized, that is, until the concentration of hypobromite ions (BrO － ) is stabilized, and is the time until the concentration change when measuring the concentration of hypobromite ions every 1 minute falls within ±5%.

[0243] <Example 31>

[0244] (Manufacture of treatment liquid)

[0245] To 94.43 g of ultrapure water, 1.14 g of periodic acid (manufactured by FUJI FILM Wako Pure Chemical Industries, Ltd.) (equivalent to 1.14% by mass, 0.05 mol / L) and 0.79 g of tetramethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., 97% by mass) (equivalent to 0.77% by mass, 0.05 mol / L) were added. After standing for 3 hours, an aqueous solution of 25% by mass of tetramethylammonium hydroxide was added until the pH reached 11, whereby 100 g of a treatment liquid having the compositions described in Tables 1 to 4 was obtained.

[0246] (Evaluation)

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

[0248] <Example 32>

[0249] (Manufacture of treatment liquid)

[0250] To 78.21 g of ultrapure water, 0.79 g of tetramethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., 97% by mass) (equivalent to 0.77% by mass, 0.05 mol / L) and 16.0 g of an aqueous solution of 25% by mass of tetramethylammonium hydroxide were added, and then 5.0 g of periodic acid (manufactured by FUJI FILM Wako Pure Chemical Industries, Ltd.) (equivalent to 5.0% by mass, 0.22 mol / L) was added, whereby 100 g of a treatment liquid having the compositions described in Tables 1 to 4 was obtained.

[0251] (Evaluation)

[0252] For the obtained treatment liquid, evaluation was carried out by the same method as in Example 1.

[0253] <Examples 33 to 35>

[0254] In Examples 33 to 35, oxidants were produced by the same method as in Example 1 according to the conditions shown in Table 7, and treatment liquids were prepared by the same method as in Example 1 such that the concentrations of bromine-containing compounds, oxidants, alkali compounds, and pH were as shown in Tables 1 to 4. Evaluation was carried out by the same method as in Example 1.

[0255] <Example 36>

[0256] (Production of tetramethylammonium bromide)

[0257] To 9.12 g of a 25% aqueous solution of tetramethylammonium hydroxide (manufactured by FUJI FILM Wako Pure Chemical Industries, Ltd.), 90.88 g of ultrapure water was added to prepare a 2.28% aqueous solution of tetramethylammonium hydroxide. Then, to 4.3 g of 47% hydrobromic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 95.7 g of ultrapure water was added to prepare 2.02% hydrobromic acid. 50 g of the 2.28% aqueous solution of tetramethylammonium hydroxide was mixed with 50 g of the 2.02% hydrobromic acid, whereby 100 g of an aqueous solution of tetramethylammonium bromide as shown in Table 9 was obtained.

[0258] (Production of treatment liquid)

[0259] To 80 g of a mixed solution of ammonium tetramethylhypochlorite aqueous solution and tetramethylammonium hydroxide obtained by the same method as in Example 1, 20 g of a 3.85% aqueous solution of tetramethylammonium bromide was added, whereby 100 g of a treatment liquid having the composition shown in Tables 1 to 4 was obtained.

[0260] (Evaluation)

[0261] For the obtained treatment liquid, evaluation was carried out by the same method as in Example 1.

[0262] <Example 37>

[0263] By the same method as in Example 3, a treatment liquid having the composition shown in Tables 1 to 4 was obtained. The pH, etching rate of ruthenium dioxide, RuO 4 gas generation amount, and hypobromite ion concentration of the treatment liquid just after production were evaluated. The evaluation of the etching rate of ruthenium dioxide was carried out by the above-mentioned "Calculation method of etching rate of ruthenium dioxide". RuO 4 The evaluation of the gas generation amount was carried out by the above-mentioned "RuO 4Quantitative analysis of the gas" was carried out. The evaluation of the hypobromite ion concentration was carried out by the above-mentioned "Calculation method of hypobromite ion concentration". The evaluation of the stability of the etching rate was carried out as described below. Every 10 hours, the etching rate of the produced treatment liquid was evaluated by the above-mentioned "Calculation method of the etching rate of ruthenium dioxide". The time when the obtained etching rate increased or decreased within ±20% of the etching rate just after production was defined as the stable time of the etching rate.

[0264] <Example 38>

[0265] A treatment liquid with a pH of 12 was prepared, which contained 0.075 g (0.05 mol / L) of sodium bromate (manufactured by Wako Pure Chemical Industries, Ltd.) and contained bromine-containing compounds, oxidants, and alkali compounds at the same concentrations as those in Example 1 shown in Table 1. For the obtained treatment liquid, evaluation was carried out by the same method as in Example 1.

[0266] <Example 39>

[0267] A treatment liquid with a pH of 12 was prepared, which contained 0.075 g (0.05 mol / L) of sodium bromate (manufactured by Wako Pure Chemical Industries, Ltd.) and contained bromine-containing compounds, oxidants, and alkali compounds at the same concentrations as those in Example 10 shown in Table 1. For the obtained treatment liquid, evaluation was carried out by the same method as in Example 1.

[0268] The compositions of the treatment liquids and the respective 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, and in Comparative Example 3 where etching was possible, the etching rate and stability were low, and the RuO 4 The gas generation amount was 2 times higher than the allowable value, so it was impossible to satisfy all of the etching rate, stability, and RuO 4 gas inhibition ability. In contrast, for the treatment liquids of the present examples, it was confirmed that all of the following three performances were satisfied: not only was the etching rate of ruthenium fast, but also the stability of the etching rate was excellent, and the RuO 4 gas inhibition effect was high. According to the results of Examples 24 to 30, it was confirmed that the time until the etching rate was stabilized for these treatment liquids was sufficiently fast within 1 hour. Example 37 and Example 3 were treatment liquids with the same hypobromite ion concentration and the same pH, and it was confirmed that they also had high etching performance for ruthenium dioxide. In Examples 38 and 39, BrO － and BrO 3 － and Br － existed in the treatment liquid, whereby the stability of the etching rate was improved.

[0269] [Table 1]

[0270]

[0271] [Table 2]

[0272]

[0273] [Table 3]

[0274]

[0275] [Table 4]

[0276]

[0277] [Table 5]

[0278]

[0279] [Table 6]

[0280]

[0281] [Table 7]

[0282]

[0283] [Table 8]

[0284]

[0285] [Table 9]

[0286]

Claims

1. A treatment liquid for a semiconductor containing ruthenium, which contains hypobromite ions, The hypobromite ions are 0.001 mol / L or more and 0.20 mol / L or less.

2. The treatment liquid for a semiconductor according to claim 1, wherein, The processing liquid for semiconductors further contains one or more HBrO 2 , BrO 2 － , HBrO 3 , BrO 3 － , - Br。 3. The treatment liquid for a semiconductor according to claim 1, wherein, The processing liquid for semiconductors further contains an oxidizing agent, and the oxidation-reduction potential of the oxidizing agent exceeds the oxidation-reduction potential of the hypobromite ion / Br － system.

4. The treatment liquid for a semiconductor according to claim 1, wherein, The oxidizing agent contained in the treatment liquid for a semiconductor is hypochlorite ions or ozone.

5. The treatment liquid for a semiconductor according to claim 1, wherein, The treatment liquid for a semiconductor further contains tetraalkylammonium ions.

6. The treatment liquid for a semiconductor according to claim 1, wherein, The tetraalkylammonium ions are tetramethylammonium ions.

7. The treatment liquid for a semiconductor according to claim 1, wherein, The proportion of the hypobromite ions in 1 mole of the bromine element contained in the treatment liquid for a semiconductor exceeds 0.5 mole.

8. The treatment liquid for a semiconductor according to claim 1, wherein, The pH of the treatment liquid is 8 or more and 14 or less.

9. The treatment liquid for a semiconductor according to claim 1, wherein, The ruthenium is a ruthenium-based metal or a ruthenium alloy.

10. A method for manufacturing a treatment liquid for a semiconductor containing ruthenium, which includes: a step of mixing a solution containing an alkali compound with hypobromous acid, a hypobromite, bromine water, or bromine gas.

11. A method for manufacturing a treatment liquid for a semiconductor containing ruthenium, which includes: a step of mixing a solution containing a hypochlorite compound and an alkali compound with a bromine-containing compound.

12. The method for manufacturing a treatment liquid for a semiconductor according to claim 11, wherein, The step of mixing a solution containing a hypochlorite compound and an alkali compound with a bromine-containing compound is a step of adding the bromine-containing compound to the solution containing the hypochlorite compound and the alkali compound and mixing them.

13. The manufacturing method according to claim 10, wherein, The ruthenium is a ruthenium-based metal or a ruthenium alloy.

14. The method for manufacturing a treatment liquid for a semiconductor according to claim 10, wherein, The alkali compound is tetramethylammonium hydroxide.

15. The method for manufacturing a treatment liquid for a semiconductor according to claim 11, wherein, The bromine-containing compound is a bromide salt or hydrogen bromide.

16. The method for manufacturing a treatment liquid for a semiconductor according to claim 15, wherein, The bromide salt is a bromonium salt.

17. The method for manufacturing a treatment liquid for a semiconductor according to claim 16, wherein, The bromonium salt is a quaternary bromonium salt or a tertiary bromonium salt.

18. The method for manufacturing a treatment liquid for a semiconductor according to claim 17, wherein, The quaternary bromonium salt is a tetraalkylammonium bromide.

19. The method for manufacturing a treatment liquid for a semiconductor according to claim 18, wherein, The tetraalkylammonium bromide is manufactured from a tetraalkylammonium hydroxide and bromide ions.

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