Semiconductor processing liquid

Abstract

To provide a process liquid for semiconductor, which has a satisfactory etching rate, which is superior in the stability in etching rate, which enables a stable etching operation over a long time even at an atmospheric temperature, and which allows the flatness of a metal surface after etching to be retained.SOLUTION: A process liquid for semiconductor comprises hypobromous ions, in which the concentration of the hypobromous ions is no less than 0.1 μmol / L and below 0.001 mol / L. A RuO4 gas generation inhibitor comprises an onium salt including an onium ion and a bromine-containing ion. In the RuO4 gas generation inhibitor, the concentration of hypobromous ions is no less than 0.1 μmol / L and below 0.001 mol / L. In addition, a halogen oxyacid production method is provided, which comprises the step of causing the reaction of a bromine salt, an organic alkaline material, and a halogen to obtain halogen oxyacid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a semiconductor processing solution (hereinafter simply referred to as "processing solution") containing hypobromite ions, wherein the concentration of the hypobromite ions is 0.1 μmol / L or more and less than 0.001 mol / L. The present invention also relates to a RuO4 gas generation inhibitor containing an onium salt composed of an onium ion and a bromine-containing ion, wherein the hypobromite ion concentration in the RuO4 gas generation inhibitor is 0.1 μmol / L or more and less than 0.001 mol / L. Furthermore, the present invention relates to a production method for obtaining a halogen oxygen acid. [Background technology]

[0002] In recent years, the design rules for semiconductor devices have become increasingly finer, leading to an increase in wiring resistance. As a result of the increase in wiring resistance, it has become apparent that the high-speed operation of semiconductor devices is being hindered, and countermeasures are therefore required. Therefore, wiring materials with higher electromigration resistance and reduced resistance than conventional wiring materials are desired.

[0003] Compared to conventional wiring materials such as aluminum and copper, ruthenium, tungsten, molybdenum, and chromium have high electromigration resistance and can reduce the resistance of wiring, which is why they are attracting attention as wiring materials, especially for semiconductor device design rules of 10 nm or less.In addition, ruthenium can prevent electromigration even when copper is used as the wiring material, so its use as a barrier metal for copper wiring, as well as a wiring material, is also being considered.

[0004] In the wiring formation process of semiconductor devices, even when ruthenium, tungsten, molybdenum, or chromium is selected as the wiring material, the wiring is formed by dry or wet etching, as with conventional wiring materials. Furthermore, since ruthenium, tungsten, molybdenum, or chromium is difficult to etch or remove by dry etching using etching gas or CMP polishing, more precise etching is desired, and specifically, wet etching has attracted attention.

[0005] When wet etching ruthenium, tungsten, molybdenum, or chromium, the dissolution rate of these metals, i.e., the etching rate, is important. A fast etching rate allows the metal to be dissolved in a short time, thereby increasing the number of wafers processed per unit time.

[0006] Furthermore, when ruthenium, tungsten, molybdenum, or chromium is used as the wiring material, the stability of the etching rate is particularly important. If the etching rate is stable, the processing accuracy of the metal can be improved by controlling the etching time. In particular, for ultra-fine wiring, precise processing of ruthenium, tungsten, molybdenum, or chromium is essential. Therefore, an etching solution that has excellent etching rate stability and can maintain the flatness of the transition metal surface is desired, especially in the process of forming fine wiring using ruthenium, tungsten, or molybdenum.

[0007] On the other hand, in order to etch ruthenium, which is a noble metal and does not dissolve easily, or in order to etch tungsten, molybdenum, or chromium at high speed, the etching solution may contain an oxidizing agent with high oxidizing power. Even in such cases, in order to improve production efficiency and maintain processing precision, the etching solution is required to have a sufficient etching rate, excellent stability of the etching rate, and be able to maintain the flatness of the metal surface after etching. .

[0008] When ruthenium is wet etched under alkaline conditions, the ruthenium is etched as, for example, RuO4 - and RuO4 2- It dissolves in the treatment solution as RuO4 - and RuO4 2- is converted to RuO4 in the processing solution, some of which is gasified and released into the gas phase. RuO4 is not only harmful to the human body because of its strong oxidizing properties, but is also easily reduced to produce RuO2 particles. Generally, particles are a major problem in the semiconductor manufacturing process because they lead to reduced yields. Given this background, it is extremely important to suppress the generation of RuO4 gas.

[0009] As a treatment liquid used to etch ruthenium from such semiconductor wafers, Patent Document 1 proposes a treatment liquid for wafers containing ruthenium, which contains hypochlorite ions and a solvent and has a pH of more than 7 and less than 12.0 at 25°C. It is disclosed that this treatment liquid contains hypochlorite ions and can remove ruthenium and tungsten adhering to the edge surface and back surface of a semiconductor wafer. Patent Document 1 also describes a production method using an ion exchange resin as a production method for a treatment liquid containing hypochlorite ions.

[0010] Patent Document 2 describes an etching composition for ruthenium-based metals, which is obtained by adding and mixing a bromine-containing compound, an oxidizing agent, a base compound, and water, and is characterized in that the amount of the bromine-containing compound added is 2 to 25 mass% in terms of the amount of bromine element, and the amount of the oxidizing agent added is 0.1 to 12 mass% relative to the total mass, and the pH is 10 or more and less than 12.

[0011] Patent Document 3 proposes an etching solution for tungsten and titanium-tungsten alloys that contains hydrogen peroxide and an alkaline component and has a pH of 7 or less. It is shown that this etching solution can stably etch electrodes and wiring of thin-film transistors in semiconductor devices and liquid crystal display devices, as well as tungsten used as wiring and barrier metal for these electrodes.

[0012] Patent Document 4 discloses a method for forming wiring by processing copper, molybdenum, etc., with a chemical solution containing an oxidizing agent and an acid. Examples of the oxidizing agent include hydrogen peroxide, persulfuric acid, nitric acid, hypochlorous acid, permanganic acid, and dichromate. It also shows an example of etching a molybdenum film using an aqueous solution containing hydrogen peroxide and a carboxylic acid as the chemical solution. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Publication No. 2019 / 142788 [Patent Document 2] International Publication No. 2011 / 074601 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-031791 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-254946 Summary of the Invention [Problem to be solved by the invention]

[0014] When etching transition metals and the like on semiconductor wafers with a processing solution, it is important to achieve both a high etching rate and a stable etching rate, and to maintain surface flatness after etching. Furthermore, when wet etching ruthenium under alkaline conditions, it is important to suppress the generation of RuO gas. Furthermore, it is also important to produce halogen oxygen acid easily and with high yield. However, according to the studies of the present inventors, it has been found that the conventional processing solutions and compositions described in prior art documents have room for improvement in the following respects.

[0015] For example, Patent Document 1 discloses a treatment solution for wafers containing ruthenium, the pH of which is higher than 7. The treatment solution described in Patent Document 1 has a ruthenium etching rate of less than 12.0. The treatment solution described in Patent Document 1 has a sufficient ruthenium etching rate, but the stability of the etching rate tends to decrease when the oxidizing agent concentration is high. Therefore, it is difficult to achieve both a high etching rate and a stable etching rate with the treatment solution for ruthenium-containing wafers described in Patent Document 1. In addition, it is difficult to maintain the flatness of the ruthenium surface after etching.

[0016] The etching composition described in Patent Document 2 can etch ruthenium at a sufficient rate. A method for preparing the etching composition is disclosed in which a base compound is added to an oxide obtained by oxidizing a bromine-containing compound with an oxidizing agent under acidic conditions, and the pH is appropriately adjusted to basic. However, the inventors conducted follow-up experiments and found that the etching composition had poor chemical stability, resulting in a problem that the etching rate of ruthenium fluctuated significantly over time. Therefore, it was difficult to achieve both a high etching rate and a stable etching rate with the etching composition described in Patent Document 2. Furthermore, it was difficult to maintain the flatness of the ruthenium surface after etching, which led to the problem of increased roughness on the metal surface.

[0017] The etching solution described in Patent Document 3 contains hydrogen peroxide as its main component, which causes problems such as an unstable etching rate due to the self-decomposition reaction of hydrogen peroxide and a short lifespan of the solution. Furthermore, the etching rate is not sufficient. Thus, with the etching solution described in Patent Document 3, it is difficult to achieve both a high etching rate and a stable etching rate. Furthermore, it is difficult to maintain the flatness of the tungsten surface after etching, which leads to the problem of increased roughness on the metal surface.

[0018] The chemical solution described in Patent Document 4 contains an oxidizing agent and an acid. The oxidizing agent disclosed in the examples of Patent Document 4 is hydrogen peroxide alone, which, as described above, has problems such as an unstable etching rate due to a self-decomposition reaction and a short lifespan of the solution. Furthermore, the etching rate is not sufficient. Thus, with the chemical solution described in Patent Document 4, it is difficult to achieve both a high etching rate and a stable etching rate. Furthermore, it is difficult to maintain the flatness of the molybdenum surface after etching, which leads to the problem of increased roughness on the metal surface.

[0019] Furthermore, Patent Documents 1 to 4 do not mention anything about suppressing RuO4 gas generation, and in fact, the treatment solutions and compositions described in Patent Documents 1 to 4 were unable to suppress RuO4 gas generation. Furthermore, there was no method for easily producing the halogen oxygen acid with high yield.

[0020] Therefore, the present invention has been made in view of the above-mentioned background art, and an object of the present invention is to provide a semiconductor processing solution that has a sufficient etching rate, an excellent stability of the etching rate, can etch stably for a long time even at room temperature, and can maintain the flatness of the metal surface after etching. It is also an object of the present invention to provide a RuO4 gas generation inhibitor that can suppress the generation of RuO4 gas when etching ruthenium. It is also an object of the present invention to provide a method for producing a halogen oxyacid simply and efficiently. [Means for solving the problem]

[0021] The present inventors have conducted extensive research to solve the above problems. They also found that by treating a semiconductor wafer with a treatment solution having a hypobromite ion concentration of 0.1 μmol / L or more but less than 0.001 mol / L, transition metals can be etched at a sufficient rate even at room temperature, stable etching can be performed, and the flatness of the metal surface after etching can be maintained. They also found that when etching ruthenium, the generation of RuO4 gas can be suppressed by using a RuO4 gas generation inhibitor having a bromine-containing ion concentration of 0.1 μmol / L or more but less than 0.001 mol / L. Furthermore, The present invention has been accomplished by discovering a method for producing halogen oxygen acids simply and efficiently.

[0022] That is, the present invention is configured as follows.

[0023] Item 1. A semiconductor processing solution containing hypobromite ions, wherein the concentration of the hypobromite ions is 0.1 μmol / L or more but less than 0.001 mol / L. Item 2. The semiconductor treatment solution according to Item 1, wherein the semiconductor contains a transition metal. Item 3. The semiconductor processing solution according to Item 1 or 2, further comprising at least one anion species selected from the group consisting of chlorate ions, chlorite ions, chloride ions, bromate ions, bromite ions, and bromide ions. Item 4. The semiconductor processing solution according to any one of Items 1 to 3, further comprising an oxidizing agent, the oxidation-reduction potential of which exceeds the oxidation-reduction potential of a hypobromite ion / bromide ion system. Item 5. The semiconductor processing solution according to Item 4, wherein the oxidizing agent is at least one oxidizing agent selected from the group consisting of hypochlorite ions, ozone, orthoperiodate ions, and metaperiodate ions. Item 6. The semiconductor processing solution according to any one of Items 1 to 5, further comprising a tetraalkylammonium ion. Item 7. The semiconductor processing solution according to any one of Items 1 to 6, wherein the processing solution has a pH of 8 or more and 14 or less. Item 8. An inhibitor for RuO4 gas generation, comprising an onium salt composed of an onium ion and a bromine-containing ion, wherein the concentration of the bromine-containing ion in the inhibitor for RuO4 gas generation is 0.1 μmol / L or more and less than 0.001 mol / L. Item 9. The RuO4 gas generation inhibitor according to Item 8, wherein the onium salt is a quaternary onium salt represented by formula (1) or a sulfonium salt represented by formula (2).

[0024] [ka]

[0025] [ka] (In formula (1), A is nitrogen or phosphorus, and R 1 , R 2 , R 3 , R 4 are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R 1 , R 2 , R 3 , R 4 is an alkyl group, R 1 , R 2 , R 3 , R 4 At least one alkyl group has 3 or more carbon atoms. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine. In formula (2), R 1 , R 2 , R 3 are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R1 , R 2 , R 3 is an alkyl group, R 1 , R 2 , R 3 At least one alkyl group among the above has 3 or more carbon atoms. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced with fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced with fluorine or chlorine. X - is a bromine-containing ion.) Item 10. The RuO4 gas generation inhibitor according to Item 9, wherein the quaternary onium salt is a tetraalkylammonium salt. Item 11. The RuO4 gas generation inhibitor according to any one of Items 8 to 10, wherein the bromine-containing ion is a bromite ion, a bromate ion, a perbromate ion, a hypobromite ion, or a bromide ion. Item 12. The RuO4 gas generation inhibitor according to any one of Items 8 to 11, further comprising an oxidizing agent. Item 13. The RuO gas generation inhibitor according to Item 12, wherein the oxidizing agent is hypochlorite ions, and the concentration of the hypochlorite ions is 500 ppb by mass or more and 20.0% by mass or less. Item 14. A method for producing a halogen oxygen acid, comprising reacting a bromine salt, an organic alkali, and a halogen to obtain the halogen oxygen acid. Item 15. The method for producing a halogen oxygen acid according to Item 14, wherein the organic alkali is onium hydroxide. Item 16. The method for producing a halogen oxygen acid according to Item 14 or 15, wherein the halogen is chlorine. Item 17. The method for producing a halogen oxygen acid according to any one of Items 14 to 16, wherein the concentration of the halogen oxygen acid is 0.1 μmol / L or more and less than 0.001 mol / L. [Effects of the Invention]

[0026] According to the semiconductor processing solution of the present invention, transition metals can be removed at a sufficient rate in the semiconductor forming process. , and stable wet etching can be achieved. Furthermore, the roughness of the transition metal surface after etching can be reduced, maintaining flatness. By achieving all of these effects, the processing accuracy of the transition metal contained in the semiconductor wafer is improved, yield is improved, and wafer processing efficiency per unit time is improved. Furthermore, the RuO4 gas generation inhibitor of the present invention can suppress the generation of RuO4 gas when etching ruthenium. Furthermore, the production method of the present invention can easily produce a halogen oxyacid with high yield. This production method can reduce the amount of metal contained in the halogen oxyacid. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic diagram illustrating an aspect of a method for measuring RuO4 gas according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] (Semiconductor processing solution) The semiconductor processing solution according to the first embodiment of the present invention (also simply referred to as the "processing solution" in this embodiment) contains hypobromite ions (BrO) of 0.1 μmol / L or more and less than 0.001 mol / L. -The present invention relates to a semiconductor wafer processing solution containing hypobromite ions. Hypobromite ions are a strong oxidizing agent. The processing solution of this embodiment, containing hypobromite ions at 0.1 μmol / L or more but less than 0.001 mol / L, can etch transition metals, for example, at a sufficient rate and stably under alkaline conditions, while maintaining the flatness of the metal surface after etching. Furthermore, by appropriately selecting the pH and the type and concentration of the oxidizing agent, the processing solution can etch transition metals at a stable etching rate while suppressing the generation of RuO gas. It can also be used, for example, to remove poorly soluble resists or to remove residues after dry etching of resists. Therefore, the processing solution of this embodiment is suitable for use in the etching process, residue removal process, cleaning process, CMP process, and other processes in semiconductor manufacturing processes. In this embodiment, the hypohalous acid refers to hypobromous acid, hypochlorous acid, or hypoiodous acid, and the hypohalous acid ions refer to hypobromite ions, hypochlorous acid ions, and hypoiodite ions.

[0029] The transition metal in this embodiment includes at least one metal selected from, for example, Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, and W. The following description will be given of an example in which the transition metal is ruthenium, tungsten, molybdenum, or chromium. By using the treatment solution of this embodiment, ruthenium, tungsten, molybdenum, or chromium adhering to the front, edge, and back surfaces of a semiconductor wafer can be stably removed at a sufficient etching rate while maintaining surface flatness. In this embodiment, a sufficient etching rate refers to an etching rate of 10 Å / min or higher when the target to be etched is ruthenium. It refers to an etching rate of 50 Å / min or higher when the target to be etched is tungsten, 50 Å / min or higher when the target to be etched is molybdenum, and 50 Å / min or higher when the target to be etched is chromium. If the etching rate of ruthenium, tungsten, molybdenum, or chromium satisfies the above numerical values, the solution can be suitably used in etching processes, residue removal processes, cleaning processes, CMP processes, and the like.

[0030] The transition metal contained in the semiconductor wafer to which the treatment solution of this embodiment is applied may be formed by any method. A widely known method in the semiconductor manufacturing process, such as CVD, ALD, sputtering, plating, etc., can be used to form a transition metal film. The transition metal contained in the semiconductor wafer to which the treatment solution of this embodiment is applied may be one type or multiple types. In this specification, the term "transition metal semiconductor" refers to a semiconductor containing a transition metal.

[0031] In this embodiment, ruthenium is not limited to ruthenium metal, and includes ruthenium element. It is sufficient if it contains, for example, Ru, RuO4 - , RuO4 2- , RuO4, RuO 2、 RuO 3、 Examples include ruthenium complexes and ruthenium alloys.

[0032] In this embodiment, tungsten refers to metallic tungsten, tungsten-based metals containing tungsten as the main component, alloys of tungsten with other metals, and compounds that essentially contain tungsten. Examples of tungsten-based metals include tungsten oxide (W X O Y ), nitride (WN), oxynitride (WNO), cobalt tungsten phosphate (CoWP), etc., and tungsten oxide here refers to tungsten dioxide (WO2), tungsten trioxide (WO3), ditungsten pentoxide (W2O5), etc. Tungsten oxide (W X O Y ) also includes cases where x and y are not expressed as integers, i.e., where they are indefinite ratios.

[0033] In this embodiment, molybdenum refers to not only metallic molybdenum, molybdenum-based metals containing molybdenum as a main component, and alloys of molybdenum with other metals, but also compounds that substantially contain molybdenum. Examples of molybdenum-based metals include molybdenum oxide (Mo X O Y), nitride (MoN), oxynitride (MoNO), etc., and here, the oxide of molybdenum refers to molybdenum dioxide (MoO2), molybdenum trioxide (MoO3), dimolybdenum pentoxide (Mo2O5), etc. Molybdenum oxide (Mo X O Y ) also includes cases where x and y are not expressed as integers, i.e., where they are indefinite ratios.

[0034] In this embodiment, chromium refers to metallic chromium, chromium-based metals containing chromium as a main component, alloys of chromium with other metals, and compounds that substantially contain chromium. Examples of chromium-based metals include chromium oxide (Cr X O Y ), nitrides (CrN), oxynitrides (CrNO), etc., and here, chromium oxide refers to chromium dioxide (CrO2), chromium trioxide (CrO3), dichromium pentoxide (Cr2O5), etc. Chromium oxide (Cr X O Y ) also includes cases where x and y are not expressed as integers, i.e., where they are indefinite ratios.

[0035] An alloy of a transition metal and another metal may contain any metal other than the transition metal. Examples of metals other than the transition metal contained in an alloy of a transition metal and another metal include tantalum, silicon, copper, hafnium, zirconium, aluminum, vanadium, cobalt, nickel, manganese, gold, rhodium, palladium, titanium, ruthenium, molybdenum, tungsten, and chromium, and the alloy may contain oxides, nitrides, carbides, and silicides of these metals.

[0036] These transition metals may be in the form of intermetallic compounds, ionic compounds, or complexes. The transition metals may be exposed on the surface of the wafer, or may be covered with other metals, metal oxide films, insulating films, resists, or the like.

[0037] The treatment solution in this embodiment can etch ruthenium, tungsten, molybdenum, or chromium, but does not etch metals such as copper, cobalt, titanium, platinum, titanium nitride, and tantalum nitride, or the etching rate for these metals is significantly slower than that for ruthenium, tungsten, molybdenum, or chromium. Therefore, in semiconductor manufacturing processes, etc., it is also possible to selectively etch ruthenium, tungsten, molybdenum, or chromium without damaging substrate materials containing these metals.

[0038] In this embodiment, the term "stable etching rate" means that the etching rate by the treatment solution containing hypobromite ions does not change over time. Specifically, when multiple wafers (where the number of wafers is n) containing transition metals are etched using the same treatment solution, the etching rate of the transition metal in the first wafer is stable compared to the etching rate in the nth wafer. This means that the etching rates of the transition metals are substantially the same. Here, "substantially the same" means that the fluctuation range of the etching rate of the transition metal for the nth wafer relative to the etching rate of the transition metal for the first wafer, i.e., the increase or decrease in the etching rate, is within ±20%. The etching rate stabilization time is defined as the time during which the etching rate of the transition metal for the nth wafer increases or decreases by ±20% relative to the etching rate of the transition metal for the first wafer. The preferred etching rate stabilization time varies depending on the conditions and manufacturing process in which the processing solution of this embodiment is used. For example, a processing solution with an etching rate stabilization time of 1 hour or more can be suitably used in semiconductor manufacturing processes. Considering the need for ample time for handling the processing solution and the ability to flexibly set the process time, a processing solution with an etching rate stabilization time of 10 hours or more is more preferred.

[0039] A treatment solution in which the etching rate of a transition metal does not change over time, or in which the etching rate remains stable for a long period of time, not only enables stable etching of a transition metal using the treatment solution in a semiconductor manufacturing process, but also enables the treatment solution to be reused, making the treatment solution excellent in terms of productivity and cost.

[0040] Furthermore, the treatment solution of this embodiment is capable of maintaining the flatness of the transition metal surface after etching. In this embodiment, maintaining the flatness of the transition metal surface after etching means that the flatness of the etched transition metal surface does not substantially change before and after etching, or if it does change, it is within a range that is not problematic for practical use. Examples of cases in which the flatness of the transition metal surface is not maintained include cases in which pitting corrosion occurs in the transition metal film or uneven etching (local unevenness) occurs due to etching, as well as cases in which the roughness of the metal surface increases. The flatness of the transition metal surface can be easily confirmed, for example, by observing the transition metal surface with a scanning electron microscope (SEM) or by observing and measuring the transition metal surface with an atomic force microscope (AFM). Therefore, by observing and measuring the surface of a transition metal-containing wafer to be etched before and after the etching process using the above-mentioned evaluation method and comparing the results, it is easy to determine whether the flatness of the metal surface after etching is maintained.

[0041] Maintaining the flatness of the transition metal surface after etching improves adhesion when other semiconductor materials, such as interlayer insulating films or other metal materials, are brought into contact with the etched transition metal, thereby improving not only the performance and reliability of the formed fine wiring and semiconductor elements, but also the yield. The flatness of the transition metal surface after etching becomes increasingly important as the wiring and elements become finer. By using the treatment solution of this embodiment, the transition metal contained in the wafer can be stably etched at a sufficient rate, and the flatness of the transition metal surface after etching can be maintained. The treatment solution of this embodiment is particularly suitable for use when the wiring width used in semiconductor manufacturing is 10 nm or less, for example.

[0042] (hypobromite ion) The hypobromite ions contained in the treatment solution of this embodiment may be generated in the treatment solution or may be added to the treatment solution as hypobromite. The term "hypobromite" as used herein refers to a salt containing hypobromite ions or a solution containing such a salt. To generate hypobromite ions in the treatment solution, for example, bromine gas may be blown into the treatment solution. In this case, from the viewpoint of efficiently generating hypobromite ions, the treatment solution is preferably kept at 50°C or below. A treatment solution of 50°C or below not only efficiently generates hypobromite ions, but also allows the generated hypobromite ions to be stably used for etching transition metals. Furthermore, in order to dissolve as much bromine as possible in the treatment solution, the temperature of the treatment solution is more preferably 30°C or below, and most preferably 25°C or below. While there is no particular lower limit for the temperature of the treatment solution, it is preferable that the treatment solution does not freeze. Therefore, the treatment solution is preferably kept at -35°C or above. The temperature is preferably not lower than −15° C., more preferably not lower than 0° C. The pH of the treatment solution into which the bromine gas is blown is not particularly limited, but if the treatment solution has an alkaline pH, it can be used to etch transition metals immediately after the generation of hypobromite ions.

[0043] Furthermore, when hypobromite ions are generated by blowing bromine gas into the treatment liquid, bromide ions (Br - ) improves the solubility of bromine gas (Br2). - or Br3 - reacts with Br3 - or Br5 - This is because the ions form complexes such as Br2 and Br, which are stable in the treatment solution. - , Br3 - , Br5 - A treatment liquid containing a large amount of the above can generate a larger amount of hypobromite ions, and therefore can be suitably used as the treatment liquid of this embodiment.

[0044] In addition, hypobromite ions can be produced in the treatment solution by oxidizing a compound containing bromine with an oxidizing agent.

[0045] To add hypobromite ions as a compound to the treatment solution, hypobromous acid, bromine water, and / or a hypobromite salt may be added. As the hypobromite salt, sodium hypobromite, potassium hypobromite, or a tetraalkylammonium hypobromite is preferred, and hypobromite or a tetraalkylammonium hypobromite is more preferred because it does not contain metal ions that are problematic in semiconductor manufacturing.

[0046] The tetraalkylammonium hypobromite can be easily obtained by passing bromine gas through a tetraalkylammonium hydroxide solution. It can also be obtained by mixing hypobromous acid with a tetraalkylammonium hydroxide solution. Furthermore, tetraalkylammonium hypobromite can also be obtained by substituting cations contained in hypobromites such as sodium hypobromite with tetraalkylammonium ions using an ion exchange resin.

[0047] The concentration of hypobromite ions in the treatment solution of this embodiment is 0.1 μmol / L or more but less than 0.001 mol / L. If the concentration is less than 0.1 μmol / L, the transition metal etching rate is slow and practically unsuitable. On the other hand, if the concentration is 0.001 mol / L or more, the hypobromite ions are more likely to decompose, for example, at high temperatures, making it difficult to stabilize the transition metal etching rate. Furthermore, if the concentration is 0.001 mol / L or more, it tends to be difficult to maintain the flatness of the transition metal surface after etching. In order to etch the transition metal stably at a sufficient rate and maintain the flatness of the metal surface after etching, the concentration of the hypobromite ions is 0.1 μmol / L or more and less than 0.001 mol / L, preferably 1 μmol / L or more and less than 0.001 mol / L, more preferably 10 μmol / L or more and less than 0.001 mol / L, even more preferably 50 μmol / L or more and less than 0.001 mol / L, and most preferably 50 μmol / L or more and less than 0.0005 mol / L.

[0048] The concentration of hypobromite ions in the treatment solution may be calculated based on the production conditions or may be determined using a widely known method. For example, by using ultraviolet-visible absorptiometry, absorption due to hypobromite ions can be easily confirmed, and the hypobromite ion concentration can be determined from the intensity of the absorption peak (generally around 330 nm, depending on the pH of the treatment solution and the hypobromite ion concentration, etc.). Furthermore, the hypobromite ion concentration can also be determined by iodometric titration. Alternatively, the hypobromite ion concentration can be determined from the oxidation-reduction potential (ORP) or pH of the treatment solution. Measurement by ultraviolet-visible absorptiometry is most preferable from the viewpoint of non-contact and continuous measurement. Note that when measuring the hypobromite ion concentration by ultraviolet-visible absorptiometry, if there is absorption due to other chemical species, the hypobromite ion concentration can be determined by performing data processing such as spectral division and baseline correction, or by appropriately selecting a reference. can be determined with sufficient accuracy.

[0049] Hypobromous acid (HBrO) and hypobromite ion (BrO - ) acid dissociation constant (pK a ) is 8.6, so when the pH is low, the pH of the treatment solution changes to HBrO and BrO. - The processing solution may contain HBrO and BrO. - If it contains HBrO and BrO - The total concentration of the above may be treated as the concentration of hypobromite ions.

[0050] Although the details of the mechanism by which hypobromite ions dissolve ruthenium are not entirely clear, it is believed that hypobromite ions or hypobromous acid generated from hypobromite ions in the treatment solution oxidize ruthenium to form RuO4, RuO4 - or RuO4 2- It is assumed that ruthenium is dissolved in the treatment solution by using RuO4 - or RuO4 2-By dissolving ruthenium as RuO4, it is possible to reduce the amount of RuO4 gas generated and suppress the generation of RuO2 particles. - or RuO4 2- In order to dissolve ruthenium as RuO4, the pH of the treatment solution is preferably alkaline, more preferably between 8 and 14, even more preferably between 12 and 14, and most preferably between 12 and 13. When the pH of the treatment solution is between 12 and 13, ruthenium dissolves in RuO4. - or RuO4 2- Since ruthenium dissolves in the treatment solution as RuO2, the amount of RuO4 gas generated can be significantly reduced, and the generation of RuO2 particles can be suppressed. On the other hand, if the pH of the treatment solution is less than 8, ruthenium is easily oxidized to RuO2 and RuO4, which tends to increase the amount of RuO2 particles and the amount of RuO4 gas generated. Furthermore, if the pH exceeds 14, ruthenium becomes less likely to dissolve, making it difficult to obtain a sufficient ruthenium etching rate, thereby reducing production efficiency in semiconductor manufacturing. If the pH of the treatment solution is between 8 and 14, ruthenium can be etched stably at a sufficient rate, the flatness of the ruthenium surface after etching can be maintained, and the amount of RuO4 gas generated can be reduced.

[0051] Although the details of the mechanism by which hypobromite ions dissolve tungsten, molybdenum, or chromium are not entirely clear, hypobromite ions or hypobromic acid generated from hypobromite ions in the treatment solution oxidize tungsten, molybdenum, or chromium, producing MO4, MO4 - or MO4 2-(Here, M represents tungsten (W), molybdenum (Mo), or chromium (Cr)) and is presumed to dissolve in the treatment solution. Dissolving tungsten, molybdenum, or chromium in the treatment solution as the above chemical species can suppress the deposition of oxides on the transition metal surface. When oxides are deposited on the transition metal surface, the etching rate of the transition metal changes significantly, reducing the stability of the etching rate and deteriorating the flatness of the metal surface. Therefore, it is preferable that tungsten, molybdenum, or chromium dissolve in the treatment solution as the above chemical species. To achieve this, it is preferable that the pH of the treatment solution is alkaline, and the pH of the treatment solution is more preferably 8 to 14, more preferably 12 to 14, and most preferably 12 to less than 13.

[0052] (anionic species) The treatment liquid of this embodiment may further contain at least one anion species selected from the group consisting of chlorate ions, chlorite ions, chloride ions, bromate ions, bromite ions, and bromide ions. It is presumed that these anion species interact with the metal to further suppress surface roughness. In other words, the inclusion of these anion species in the treatment liquid of this embodiment makes it easier to maintain the flatness of the transition metal surface after etching. The treatment liquid may contain one type of these anion species, or two or more types of anion species. Among these, bromide ions are preferred in terms of solubility in the treatment liquid, ease of availability, cost, etc. When two or more types of anions are contained in the treatment liquid, chloride ions, chlorate ions, bromide ions, and the like are preferred in terms of effectively suppressing roughness of the metal surface. It is particularly preferred that the anion contained is selected from chloride ions and bromate ions.

[0053] The anion species used in this embodiment can be generated by dissolving an acid or salt containing the anion species in the treatment solution. Examples of acids containing anion species include chloric acid, chlorous acid, hydrogen chloride, bromic acid, bromous acid, and hydrogen bromide. Examples of salts containing anion species include alkali metal salts, alkaline earth metal salts, and organic salts. Specifically, alkali metal salts include sodium chloride, sodium chlorate, sodium chlorite, potassium bromide, and sodium bromite. Examples of organic salts include organic salts containing onium ions, such as quaternary alkyl ammonium salts, such as tetramethylammonium chloride and tetramethylammonium bromide. Hydrogen bromide can also be generated by dissolving a halogen gas, such as bromine gas, in water. Among these, acids and organic salts containing anion species are preferred because they do not contain metals that can reduce yields in semiconductor manufacturing. Furthermore, organic salts containing onium ions, such as quaternary alkyl ammonium salts, are even more preferred in terms of industrial availability and ease of handling. Among organic salts, those that can be particularly preferably used in terms of stability, purity, and cost include one or more selected from the group consisting of tetramethylammonium chloride, tetramethylammonium bromide, ethyltrimethylammonium chloride, ethyltrimethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetramethylammonium chlorate, tetramethylammonium bromate, tetramethylammonium chlorite, tetramethylammonium bromite, and the like.

[0054] The content of anionic species in the treatment solution is not particularly limited and can be determined appropriately taking into account the type and stability of the anions, the concentration of hypobromite ions, the types and amounts of other additives described below, and etching conditions (e.g., treatment time, treatment temperature, etc.). Generally, a long etching time or a large etching amount tends to deteriorate the flatness of the metal surface. In such cases, increasing the amount of anionic species contained in the treatment solution of this embodiment can maintain the flatness of the metal surface after etching. For example, the content of anionic species contained in the treatment solution is 0.01 μmol / L or more and 10.0 mol / L or less, preferably 0.01 mmol / L or more and 7.00 mol / L or less, and more preferably 1 mmol / L or more and 5.00 mol / L or less. The content of anionic species in the treatment solution can be measured using ion chromatography. Using this measurement method, anionic species can be identified and quantified by appropriately selecting the type and conditions of the column.

[0055] (oxidizing agents other than hypobromite ion) In the treatment solution of this embodiment, hypobromite ions act as an oxidizing agent to etch transition metals. The treatment solution preferably further contains an oxidizing agent different from hypobromite ions. By including an oxidizing agent in the treatment solution of this embodiment, bromide ions (Br - ) back to hypobromite ions.

[0056] When oxidizing transition metals, the hypobromite ion is converted to Br - In addition, hypobromite ions are easily decomposed spontaneously in the treatment solution, and some of them are reduced to Br - Furthermore, the decomposition of hypobromite ions is accelerated by ultraviolet and visible light, and some of them become Br - Furthermore, hypobromite ions are decomposed by heating, contact with acid, or contact with metals, and some of them become Br - The Br produced by the reduction and decomposition of hypobromite ions -Since Br does not dissolve transition metals, the etching rate of transition metals decreases as the reduction or decomposition of hypobromite ions progresses. By including an appropriate oxidizing agent in the treatment solution, the Br generated by reduction or decomposition can be reduced. - The oxidizing agent can be oxidized to hypobromite ions, which can slow down the decrease in the etching rate of transition metals. This increases the time it takes for the etching rate to stabilize.

[0057] The oxidizing agent that may be contained in the treatment solution is an oxidizing agent having a redox potential between the oxidizing agent and a chemical species generated by reduction of the oxidizing agent that is lower than the redox potential of hypobromite ion (BrO - ) / bromide ion (Br - The redox potential of the hypobromite ion / bromide ion system is the redox potential in the following reaction formula (3), and refers to the potential at equilibrium between hypobromite ion, which is the oxidant, and bromide ion, which is the reductant, present during the treatment. BrO - + 2H2O + 2e - → Br - + 2OH - (3) In other words, the redox potential of the oxidizing agent exceeds the redox potential of hypobromite ion / bromide ion system means that the redox potential between the oxidizing agent and a chemical species generated by the reduction of the oxidizing agent exceeds the redox potential between hypobromite ion and a bromide ion system generated by the reduction of the hypobromite ion. By using such an oxidizing agent, Br - The oxidation-reduction potential between an oxidizing agent that may be contained in the treatment solution and a chemical species generated by the reduction of the oxidizing agent varies depending on the concentrations of the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent, the temperature and pH of the treatment solution, etc. However, regardless of these conditions, the oxidation-reduction potential between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent can be reduced to BrO - / Br -On the other hand, the upper limit of the oxidation-reduction potential between the oxidizing agent and the chemical species produced by reduction of the oxidizing agent that may be contained in the treatment solution is not particularly limited as long as it does not deviate from the object of the present invention.

[0058] The oxidizing agent that may be contained in the treatment solution of this embodiment does not contain any metal elements that are problematic in semiconductor manufacturing, and therefore is hypochlorite ions (ClO - It is preferable to use ozone, orthoperiodate ion, or metaperiodate ion. Among these, hypochlorite ion is more preferable because it has high solubility in the treatment solution, is stable in the solution, and its concentration can be easily adjusted.

[0059] Hypochlorite ions, ozone, orthoperiodate ions, and metaperiodate ions are Br in alkaline processing solutions (pH 8 to 14). - to hypobromite ion. This is the case, for example, with ClO - / Cl - The redox potential of the ozone / oxygen system is 0.89 V, and the redox potential of the ozone / oxygen system is 1.24 V. - / Br - This can also be seen from the fact that the oxidation-reduction potential of the system is 0.76 V. The above oxidation-reduction potential is a value relative to a standard hydrogen electrode at pH 14 (25°C). Therefore, the treatment solution of this embodiment containing hypobromite ions and hypochlorite ions or ozone has a Br - By oxidizing to hypobromite ions, the concentration of hypobromite ions in the treatment solution can be maintained at a high concentration, and therefore the etching rate of transition metals can be stabilized.

[0060] The treatment solution of this embodiment, which contains both hypobromite ions and hypochlorite ions, is particularly suitable for use because it prolongs the time during which the etching rate of ruthenium stabilizes. On the other hand, when an alkaline oxidizing agent with weak oxidizing power, such as hydrogen peroxide, is used, the Br - Since ruthenium cannot be efficiently oxidized to hypobromite ions, the etching rate of ruthenium is low and it is difficult to stabilize the etching rate of transition metals.

[0061] When hypochlorite ions are contained in the treatment solution of this embodiment, the concentration of the hypochlorite ions is not limited as long as it does not deviate from the spirit of the present invention, but is preferably 0.1 μmol / L or more and 4 mol / L or less. If the concentration of hypochlorite ions is less than 0.1 μmol / L, Br - The ruthenium cannot be efficiently oxidized, and the etching rate of ruthenium decreases. On the other hand, if the amount of hypochlorite ions added is more than 4 mol / L, the stability of the hypochlorite ions decreases, which is not appropriate. From the viewpoint of achieving both the suppression of RuO4 gas generation and the etching rate of ruthenium, the concentration of the oxidizing agent, which is the sum of hypobromite ions and other oxidizing agents, is more preferably 1 μmol / L or more and 2 mol / L or less, and more preferably 10 μmol / L or more and 2 mol / L or less. It is most preferable that the concentration is 1 / L or less.

[0062] On the other hand, if the ratio of hypochlorite ions to hypobromite ions is high, the reaction between hypochlorite ions and hypobromite ions progresses, converting hypobromite ions into bromate ions, resulting in a decrease in the hypobromite ion concentration. Since a decrease in hypobromite ion concentration leads to a decrease in the etching rate of transition metals, it is important to stabilize the hypobromite ion concentration. The hypobromite ion concentration can be stabilized by controlling the ratio of hypobromite ions to hypochlorite ions contained in the treatment solution.

[0063] The ratio of hypobromite ions to hypochlorite ions contained in the treatment solution is determined by the rate of reduction of hypobromite ions, or more precisely, the rate of reduction and / or decomposition of hypobromite ions. - The rate at which Br is produced and the rate at which Br is produced by hypochlorite ions - From BrO -However, in reality, since these reactions are affected by a number of factors in a complex manner, it is difficult to determine an appropriate ratio of hypobromite ions to hypochlorite ions. However, if the ratio of the molar concentration of hypobromite ions to the molar concentration of hypochlorite ions (molar concentration of hypobromite ions / molar concentration of hypochlorite ions) is in the range of 0.001 to 100, BrO - Br produced by the reduction or decomposition reaction of - is converted again to BrO by hypochlorite ions. - This stabilizes the etching rate of the transition metal.

[0064] The method for generating the hypochlorite ions is not particularly limited, and hypochlorite ions generated by any method can be suitably used in the treatment solution of this embodiment. As a method for generating hypochlorite ions, for example, the addition of hypochlorite or the blowing of chlorine gas can be suitably used. Among them, the method of adding hypochlorite to the treatment solution is more suitable because it is easy to control the concentration of hypochlorite ions and the handling of the hypochlorite is easy. Examples of such hypochlorite salts include tetraalkylammonium hypochlorite, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, and hypochlorous acid. Among them, tetraalkylammonium hypochlorite or hypochlorous acid are particularly suitable because they do not contain metals that are problematic in semiconductor manufacturing, and tetraalkylammonium hypochlorite is most suitable because it can exist stably even at high concentrations.

[0065] The tetraalkylammonium hypochlorite is preferably a tetraalkylammonium hypochlorite containing a tetraalkylammonium ion having 1 to 20 carbon atoms per alkyl group. Specific examples include tetramethylammonium hypochlorite, ethyltrimethylammonium hypochlorite, tetraethylammonium hypochlorite, tetrapropylammonium hypochlorite, tetrabutylammonium hypochlorite, tetrapentylammonium hypochlorite, and tetrahexylammonium hypochlorite. From the viewpoint of having a large amount of hypochlorite ions per unit weight, tetramethylammonium hypochlorite, ethyltrimethylammonium hypochlorite, and tetraethylammonium hypochlorite are more preferred. Tetramethylammonium hypochlorite is the most preferred because high-purity products are readily available.

[0066] The method for producing the above-mentioned tetramethylammonium hypochlorite is not particularly limited, and can be produced by widely known methods.For example, the tetramethylammonium hypochlorite produced by the method of blowing chlorine into tetramethylammonium hydroxide, the method of mixing hypochlorous acid and tetramethylammonium hydroxide, the method of replacing the cation in the hypochlorite solution with tetramethylammonium using ion exchange resin, or the method of mixing the distillate of the solution containing hypochlorite and tetramethylammonium hydroxide can be suitably used.

[0067] The concentration of hypohalite ions in the treatment solution can be calculated when the treatment solution is produced, or can be confirmed using a known method. Specifically, the measurement method is to confirm the absorption caused by hypohalite ions by ultraviolet-visible absorptiometry, and the concentration of hypohalite ions can be determined from the intensity of the absorption peak and a calibration curve prepared using a hypohalite ion solution with a known concentration. The concentration of hypohalite ions can also be determined by titration.

[0068] When orthoperiodate ions or metaperiodate ions are contained in the treatment solution of this embodiment, the concentration of the orthoperiodate ions or metaperiodate ions is not limited as long as it does not deviate from the spirit of the present invention, but is preferably 0.1 μmol / L or more and 4 mol / L or less. If the concentration of the orthoperiodate ions or metaperiodate ions is less than 0.1 μmol / L, Br - In this case, the ruthenium cannot be efficiently oxidized, and the etching rate of ruthenium decreases. On the other hand, if the amount of orthoperiodate ions or metaperiodate ions added is greater than 4 mol / L, the stability of the orthoperiodate ions or metaperiodate ions decreases, which is not appropriate. From the viewpoint of simultaneously suppressing RuO gas generation and increasing the etching rate of ruthenium, even when orthoperiodate ions or metaperiodate ions are contained in the treatment solution of this embodiment, the concentrations of all oxidizing agents are more preferably 1 μmol / L or more and 2 mol / L or less, and most preferably 10 μmol / L or more and 2 mol / L or less.

[0069] (pH of treatment solution, organic alkali) In this embodiment, the pH of the transition metal semiconductor treatment solution is preferably 8 to 14, more preferably 8 to 13, and most preferably 10 to 13. When the pH of the treatment solution is 8 to 14, the transition metal can be efficiently etched. If the pH of the treatment solution is lower than 8, hypobromite ions are decomposed, making etching difficult to proceed. On the other hand, if the pH of the treatment solution exceeds 14, the oxidizing agent is decomposed, which may cause the oxidation of the bromine-containing compound to become unstable. This means that the etching rate of the transition metal is unstable, which complicates process control in the semiconductor manufacturing process and must be avoided.

[0070] To adjust the pH of the treatment solution, an acid or alkali can be added to the treatment solution. The acid may be either an inorganic or organic acid, including, for example, hydrofluoric acid, hydrochloric acid, hydrobromic acid, nitric acid, acetic acid, sulfuric acid, peroxodisulfuric acid, carboxylic acids such as formic acid, and other widely known acids used in semiconductor treatment solutions. Organic alkalis are preferred because they do not contain metal ions that are problematic in semiconductor manufacturing. An example of an organic alkali is tetraalkylammonium hydroxide, which is composed of a tetraalkylammonium ion and a hydroxide ion. Examples of tetraalkylammonium hydroxides include tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. Among these, the organic alkali is preferably tetraalkylammonium hydroxide, and more preferably tetramethylammonium hydroxide or ethyltrimethylammonium hydroxide, because they have a large number of hydroxide ions per unit weight and are readily available as high-purity products. If desired, a pH buffer may be added to the treatment solution. Examples of the pH buffer include widely known pH buffers, such as phosphoric acid, boric acid, carbonic acid, oxalic acid, and salts thereof.

[0071] (Tetraalkylammonium ion) In order to adjust the pH of the processing solution, an acid or alkali may be added to the processing solution. As the alkali, an organic alkali is preferably used because it does not contain metal ions that are problematic in semiconductor manufacturing. Among organic alkalis, an onium salt containing an onium ion is preferably used. An example of an onium salt is tetraalkylammonium hydroxide, which is composed of a tetraalkylammonium ion and a hydroxide ion. The number of carbon atoms in the alkyl of the tetraalkylammonium ion derived from the tetraalkylammonium hydroxide can be 1 to 20, preferably 1 to 10. Examples of tetraalkylammonium hydroxides include tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. Among these, tetraalkylammonium hydroxide is preferred because it has a large number of hydroxide ions per unit weight and is readily available as a high-purity product, and tetramethylammonium hydroxide or ethyltrimethylammonium hydroxide is more preferred.

[0072] The treatment liquid may contain one type of tetraalkylammonium ion, or a combination of two or more types of tetraalkylammonium ions.

[0073] The processing solution of this embodiment may further contain a RuO4 gas generation inhibitor. By including a RuO4 gas generation inhibitor in the processing solution, it is possible to suppress RuO4 gas generated from ruthenium oxide dissolved in the processing solution when processing a wafer containing ruthenium. Examples of such RuO4 gas generation inhibitors include RuO4, RuO4 - , RuO4 2- It is preferable that the RuO4 gas generation inhibitor contains a compound having a ligand that coordinates with the above RuO4, RuO4 - , RuO4 2-Specific examples of compounds having a ligand that coordinates with the above include compounds having a carboxyl group or a carbonyl group, such as oxalic acid, dimethyl oxalate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, succinic acid, acetic acid, butane-1,2,3,4-tetracarboxylic acid, dimethylmalonic acid, glutaric acid, diglycolic acid, citric acid, malonic acid, 1,3-adamantanedicarboxylic acid, and 2,2-bis(hydroxymethyl)propionic acid, as well as nitrogen-containing heterocyclic compounds, such as pyridine compounds, piperazine compounds, triazole compounds, pyrazole compounds, and imidazole compounds. Furthermore, examples of RuO gas generation inhibitors include onium salts composed of onium ions and bromine-containing ions. From the viewpoints of high RuO gas generation inhibitory effect, low metal content that is problematic in semiconductor manufacturing, and industrially low-cost production, RuO gas generation inhibitors containing onium salts composed of onium ions and bromine-containing ions, as described below, are more preferred.

[0074] (solvent) Water is most preferably used as the solvent for the treatment liquid of this embodiment. The water contained in the treatment liquid of this embodiment is preferably water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filtration, various adsorption treatments, etc., and pure water or ultrapure water is particularly preferred. Such water can be obtained by known methods widely used in semiconductor manufacturing.

[0075] Alternatively, an organic solvent may be used as long as the hypohalite ions are stable in the solvent, such as acetonitrile or sulfolane.

[0076] Furthermore, water and an organic solvent may be used in combination as the solvent. By using water and an organic solvent in combination, oxidation of the transition metal proceeds relatively slowly, thereby suppressing oxidation of wiring and the like in the circuit formation portion. When water and an organic solvent are used in combination, the mass ratio of water to organic solvent (water / organic solvent) may be about 60 / 40 to 99.9 / 0.1.

[0077] (Other additives) The treatment solution of this embodiment may contain other additives conventionally used in semiconductor treatment solutions, as desired, within the scope of the present invention. For example, other additives may include acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidizing agents, reducing agents, complexing agents, chelating agents, surfactants, antifoaming agents, pH adjusters, and stabilizers. These additives may be added alone or in combination.

[0078] (Method of manufacturing the treatment liquid) The method for producing the semiconductor processing solution of this embodiment is not particularly limited. For example, it can be suitably produced by the manufacturing method described in the third embodiment of the present invention, which will be described later. Alternatively, the processing solution of this embodiment may be prepared by adding hypobromite ions, hypobromous acid, and / or hypobromite salt to a solvent such as water to a desired concentration, and then adding additives as necessary to adjust the pH to a desired level. Alternatively, the processing solution of this embodiment may be prepared by preparing multiple solutions (hereinafter also referred to as "preparation materials") containing each component separately and mixing these preparation materials immediately before processing semiconductor wafers. When multiple preparation materials are prepared and mixed to produce the processing solution of this embodiment, the components contained in the preparation materials may be those that react with the components in the preparation materials after mixing to produce hypobromite ions. The pH and composition of the processing solution of this embodiment may change over time, which may result in changes in etching performance, such as etching rate. Therefore, from the viewpoint of suppressing deterioration of etching performance due to changes over time, a preferred production method is to prepare a plurality of preparation materials and mix these preparation materials immediately before processing the semiconductor wafer to obtain the processing solution of this embodiment. When preparing a plurality of preparation materials, the number of preparation materials may be prepared for each component, but in consideration of operability during mixing, it is preferable to use two types of preparation materials.

[0079] Below, we will explain in detail the method for producing the processing liquid of this embodiment, in which two types of processing materials, a first solution (processing material) and a second solution (processing material), are prepared and mixed together immediately before processing the semiconductor wafer.

[0080] (Materials for preparation) The advantage of using two preparation materials, the first solution (preparation material) and the second solution (preparation material), is, for example, improved stability of etching performance in a treatment solution containing hypobromite ions. That is, when the treatment solution is a single solution, the etching performance, such as the etching rate, may change due to decomposition of hypobromite ions over time between the production of hypobromite ions and the processing of semiconductor wafers at a semiconductor manufacturing factory. On the other hand, when the treatment solution is prepared as two preparation materials, the first solution (preparation material) and the second solution (preparation material), and hypobromite ions are generated by mixing the preparation materials, a treatment solution containing hypobromite ions is produced at a semiconductor manufacturing factory immediately before processing semiconductor wafers. This suppresses decomposition of hypobromite ions, enabling stable etching performance. In particular, when the treatment solution of this embodiment is used in, for example, an etch-back process, microfabrication is required, and precise control of the etching rate and surface roughness is necessary. Therefore, the above-described embodiment is preferred.

[0081] Therefore, when preparing the treatment liquid as two types of preparation materials, the first solution (preparation material) and the second solution (preparation material), from the viewpoint of the storage stability of the preparation materials themselves and the ability to stably suppress metal surface roughness, it is preferable that the components in the two types of solutions that make up each preparation material be as follows. First solution (preparation material): a solution containing at least one anion species selected from bromate ions, bromite ions, and bromide ions Second solution (preparation material): A solution containing hypohalite ions

[0082] Here, to generate hypobromite ions by mixing two preparation materials, the first solution (preparation material) and the second solution (preparation material), the first solution (preparation material) needs to contain bromide ions, and the second solution (preparation material) needs to contain hypohalite ions, which have a higher oxidizing power than the bromide ions in the first solution (preparation material). Examples of such hypohalite ions include hypochlorite ions. Specifically, to produce a treatment solution containing hypobromite ions, the first solution (preparation material) needs to contain bromide ions, and the second solution (preparation material) needs to contain hypochlorite ions. Because the oxidation-reduction potential of hypochlorite ion-chloride ion (0.89 V (at 25°C, pH 14, vs. standard hydrogen electrode)) is higher than the oxidation-reduction potential of hypobromite ion-bromide ion (0.76 V (same as above)), by mixing the first solution and the second solution, bromide ion is oxidized by hypochlorite ion to generate hypobromite ion, and a treatment solution containing hypobromite ion can be produced. In this case, hypochlorite ion is reduced to chloride ion. The bromide ion contained in the first solution (preparation material) may be added as bromide ion, as described below, or may be bromide ion generated by decomposition of bromate ion, bromite ion, and / or hypobromite ion.

[0083] (Method for preparing the first solution (preparation material)) In this embodiment, the method for preparing the first solution (preparation material) is not particularly limited. Specifically, at least one anion species selected from bromate ions, bromite ions, and bromide ions can be added to a solvent such as water to prepare the first solution (preparation material) of this embodiment. Other additives, etc., can also be added to the first solution (preparation material) as needed. When hypobromite ions are generated by mixing two preparative materials, the first solution (preparation material) and the second solution (preparation material), if bromide ions are contained in the first solution (preparation material), the ions can be obtained, for example, by dissolving a salt or the like that generates the ions upon dissolution into the solution. Examples of substances that form bromide ions include metal salts such as sodium bromide, organic salts such as tetraalkylammonium bromide, bromine gas, and hydrogen bromide. Among these, organic salts, bromine gas, and hydrogen bromide are preferred because they do not contain metals that can reduce yields in semiconductor manufacturing. From the viewpoints of industrial availability and ease of handling, organic salts are more preferred as raw materials for bromide ions. Among these organic salts, organic salts containing onium ions such as tetramethylammonium bromide, ethyltrimethylammonium bromide, tetraethylammonium bromide, and tetrapropylammonium bromide are particularly suitable from the viewpoints of stability, purity, and cost.

[0084] The organic salt used in this embodiment can be, for example, tetraalkylammonium bromide produced from tetraalkylammonium ions and bromide ions. The method for producing tetraalkylammonium bromide involves simply mixing an aqueous solution containing tetraalkylammonium hydroxide with an aqueous solution containing bromide ions, or a bromine-containing gas that generates bromide ions when dissolved in water, such as hydrogen bromide. Examples of tetraalkylammonium hydroxides used to produce tetraalkylammonium bromide include tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. Among these, tetramethylammonium hydroxide or ethyltrimethylammonium hydroxide is more preferred because of their high hydroxide ion count per unit weight and the ease with which high-purity products are available. Examples of bromide ion sources that generate bromide ions used to produce tetraalkylammonium bromide include hydrogen bromide, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, and ammonium bromide. Among these, tetraalkylammonium hydroxides are preferred because they are substantially metal-free, industrially readily available, and highly pure. Hydrogen bromide is preferred because it is readily available.

[0085] The concentration of at least one anion species selected from bromate ions, bromite ions, and bromide ions contained in the first solution (preparation material) may be appropriately set so as to achieve a desired concentration when mixed with the second solution to form the treatment solution of this embodiment. For example, if hypobromite ions are not generated by mixing the first solution (preparation material) with the second solution (preparation material), the concentration of the anion species contained in the first solution (preparation material) may be set taking into account the volume of the treatment solution after mixing. On the other hand, if hypobromite ions are generated by mixing the first solution (preparation material) with the second solution (preparation material), the concentration of bromide ions contained in the first solution (preparation material) may be set taking into account the amount of bromide ions consumed to generate hypobromite ions.

[0086] The pH of the first solution is not particularly limited and may be appropriately adjusted so that the desired pH of the treatment liquid of this embodiment is achieved after mixing with the second solution. To suppress pH changes after mixing, a pH of 7 to 14 is desirable, and a pH of 8 to 14 is more preferable. A solution within this pH range can minimize the decrease in pH that occurs upon mixing with the second solution described below, enabling the treatment liquid of this embodiment to be produced, stored, and used stably. When the pH of the first solution is set to less than 8, the pH and volume of the first solution may be adjusted so that the treatment liquid after mixing with the second solution has an alkaline pH. Other components contained in the first solution include preferably the solvents, other additives, and pH adjusters described above for the treatment liquid of this embodiment.

[0087] (Method for preparing the second solution (preparation material)) In the present invention, the method for preparing the second solution (preparation material) is not particularly limited. Specifically, hypohalite ions can be added to a solvent such as water, and additives can be added as needed to produce the second solution (preparation material) of this embodiment. For the hypohalite ions, sources such as sodium hypochlorite, sodium hypobromite, tetraalkylammonium hypochlorite, and tetraalkylammonium hypobromite can be used. Among these, tetraalkylammonium hypochlorite and tetraalkylammonium hypobromite are preferred, as they do not contain metals that can reduce yields in semiconductor fabrication processes. These tetraalkylammonium hypohalites can be prepared by known methods. For example, aqueous solutions containing tetraalkylammonium hypochlorite and tetraalkylammonium hypobromite can be prepared by preparing an aqueous solution of tetraalkylammonium hydroxide and then blowing chlorine or bromine into the solution, respectively. Alternatively, a solution containing tetraalkylammonium hypochlorite or tetraalkylammonium hypobromite can also be prepared by contacting a tetraalkylammonium hydroxide solution with a cation exchange type ion exchange resin to convert the cations in the ion exchange resin into tetraalkylammonium ions, and then passing a sodium hypochlorite solution or a sodium hypobromite solution through the resin to exchange the sodium ions for the tetraalkylammonium ions.

[0088] The concentration of hypohalite ions contained in the second solution (preparation material) may be appropriately set so as to achieve the desired concentration when mixed with the first solution to form the treatment liquid of this embodiment. For example, when mixing the first solution (preparation material) and the second solution (preparation material) without generating hypobromite ions, the concentration of hypohalite ions contained in the second solution (preparation material) may be set taking into account the volume of the treatment liquid after mixing. On the other hand, when mixing the first solution (preparation material) and the second solution (preparation material) to generate hypobromite ions, the concentration of hypohalite ions contained in the second solution (preparation material) may be set taking into account the amount of hypohalite ions consumed to generate hypobromite ions.

[0089] The pH of the second solution is not particularly limited, and may be appropriately set so that the desired pH of the treatment liquid of this embodiment is achieved when mixed with the first solution. To suppress pH changes after mixing, the pH is preferably 7 to 14, more preferably 10 to 14, and particularly preferably 12 to 14. A solution within this pH range can minimize the decrease in pH that occurs when mixed with the first solution, allowing for stable production, storage, and use of the treatment liquid of this embodiment. Other components contained in the second solution include preferably the solvents, other additives, and pH adjusters described above for the treatment liquid of this embodiment.

[0090] The treatment solution and preparation materials of this embodiment are preferably produced and stored at low temperatures, in the dark, and free of amines. Production and storage at low temperatures, in the dark, and free of amines is expected to suppress decomposition of the oxidizing agent and anionic species in the treatment solution. Furthermore, production and storage of the treatment solution and preparation materials in a container filled with an inert gas prevents carbon dioxide contamination, thereby maintaining the stability of the treatment solution. Furthermore, the inner surface of the container, i.e., the surface that comes into contact with the treatment solution, is preferably made of glass or an organic polymer material. Forming the inner surface of the container from glass or an organic polymer material further reduces the inclusion of impurities such as metals, metal oxides, and organic substances.

[0091] (Composition of preparation materials) In the method for producing a treatment liquid according to this embodiment, the concentrations of the components contained in the two preparation materials, the first solution (preparation material) and the second solution (preparation material), are not particularly limited, and may be prepared so as to achieve the desired composition when the preparation materials are mixed together to form a treatment liquid.

[0092] Specifically, when a treatment liquid is used that contains hypobromite ions at 0.1 μmol / L or more and less than 0.001 mol / L, and contains, as anion species, bromide ions at 0.01 μmol / L or more and less than 5.0 mol / L, bromite ions at 0.01 μmol / L or more and less than 5.0 mol / L, and bromate ions at 0.01 μmol / L or more and less than 5.0 mol / L, the first solution (preparation material) contains, as anion species, bromide ions at 0.22 The solution contains 0.2 μmol / L to 0.002 mol / L of hypochlorite ions, 0.02 μmol / L to 10.002 mol / L of bromite ions, and 0.02 μmol / L to 10.0 mol / L of bromate ions. The second solution (preparation material) is a solution containing 0.2 μmol / L to 0.002 mol / L of hypochlorite ions. These preparation materials may be mixed together before processing the semiconductor wafers to form a processing liquid for the semiconductor wafers.

[0093] Alternatively, when obtaining a treatment solution containing hypobromite ions of 0.1 μmol / L or more and less than 0.001 mol / L and hypochlorite ions of 0.1 μmol / L or more and 4 mol / L or less as hypohalite ions in the treatment solution, and containing bromate ions of 0.01 μmol / L or more and less than 5.0 mol / L as anion species, and further containing chloride ions of 0.1 μmol / L or more and less than 5.0 mol / L and chlorate ions of 0.01 μmol / L or more and less than 5.0 mol / L as other components, the first solution (preparation material ) is a solution containing bromide ions of 0.2 μmol / L or more and less than 0.002 mol / L, chloride ions of 9.998 mol / L or less, chlorate ions of 0.02 μmol / L or more and less than 10.0 mol / L, and bromate ions of 0.02 μmol / L or more and less than 10.0 mol / L, and the second solution (preparation material) is a solution containing hypochlorite ions of 0.4 μmol / L to 8.002 mol / L, and these preparation materials may be mixed together before processing the semiconductor wafers to form a processing liquid for the semiconductor wafers.

[0094] (Method of mixing ingredients for preparation) The first solution (preparation material) and the second solution (preparation material) can be mixed using a method widely known as a method for mixing semiconductor chemicals. For example, a method using a mixing tank can be used. Suitable methods include mixing within the piping of a semiconductor manufacturing apparatus (in-line mixing), and mixing by simultaneously pouring multiple liquids onto a wafer. When generating hypobromite ions by mixing the first solution (preparation material) and the second solution (preparation material), it is preferable to mix the preparation materials in advance and bring them into contact with the semiconductor wafer after sufficient hypobromite ions have been generated, in order to ensure the generation of hypobromite ions.

[0095] The temperature at which the preparation materials are mixed is not particularly limited as long as the mixed treatment liquid is homogeneous, and is generally set appropriately within the range of 0 to 80°C. When hypobromite ions are generated by mixing the preparation materials, the faster the hypobromite ions are generated, the better, so the shorter the mixing time is. One method for shortening the mixing time is to increase the temperature during mixing, but the higher the temperature, the more likely the decomposition of hypohalite ions contained in the second solution or the mixed treatment liquid tends to proceed. For these reasons, when hypobromite ions are generated by mixing the preparation materials, the temperature during mixing of the preparation materials is more preferably 10 to 60°C, and most preferably 20 to 50°C.

[0096] Furthermore, when the first solution (preparation material) and the second solution (preparation material) are mixed without generating hypobromite ions, the mixing time for the preparation materials may be continued until the temperature and composition concentration of the treatment liquid after mixing become uniform, and may be set appropriately within 30 minutes. On the other hand, when the first solution (preparation material) and the second solution (preparation material) are mixed to generate hypobromite ions, a longer mixing time is preferable to ensure the generation of hypobromite ions, but from the viewpoint of throughput, the mixing time may be set appropriately within 60 minutes.

[0097] Furthermore, in the treatment solution of this embodiment, the content of metals, specifically sodium, potassium, aluminum, magnesium, iron, nickel, copper, silver, cadmium, and lead, is preferably 1 ppb or less. To prevent the inclusion of these metals, reactors, piping, and the like, whose surfaces in contact with the solution are made of organic polymer materials, can be used. Examples of organic polymer materials that can be used include vinyl chloride resins (soft and hard vinyl chloride resins), nylon resins, silicone resins, polyolefin resins (polyethylene, polypropylene), and fluororesins. Among these, fluororesins are preferred, considering their ease of molding, solvent resistance, and low impurity elution.

[0098] The treatment solution of this embodiment, and the halogen oxyacid salts, oxidizers, tetraalkylammonium salts, acids, alkalis, water, solvents, and other additives used therein, preferably contain small amounts of ammonia and amines. This is because the presence of ammonia and amines in the treatment solution can react with the oxidizer, halogen oxyacid salts, and halogen oxyacid ions, reducing the stability of the treatment solution. For example, when tetramethylammonium hydroxide is used as the alkali, the ammonia and amines, particularly trimethylamine, contained in the base compound can reduce the stability of the treatment solution. Therefore, when tetramethylammonium hydroxide is used in the treatment solution of this embodiment, it is preferable that the total amount of amines contained in the base compound be, for example, 100 ppm or less. If the total amount of amines is 100 ppm or less, the effects of reactions with the oxidizer, bromine-containing compounds, and transition metal-etching chemical species generated from the bromine-containing compounds are minimal, and the stability of the treatment solution is not impaired.

[0099] When producing the treatment liquid of this embodiment, it is preferable to shield the liquid from light in order to prevent the halogen oxygen acid ions, oxidizing agent, and other additives from being decomposed by light.

[0100] In addition, in the production of the treatment liquid of this embodiment, it is preferable to prevent carbon dioxide from dissolving in the treatment liquid. When the treatment liquid of this embodiment is alkaline, carbon dioxide easily dissolves in the treatment liquid, which can cause a change in pH. When the pH of the treatment liquid changes, the transition metal Not only does this cause fluctuations in the etching rate, but it also reduces the stability of the processing solution. Dissolution of carbon dioxide into the processing solution can be reduced by purging the carbon dioxide from the manufacturing equipment by flowing inert gas, or by carrying out the reaction in an inert gas atmosphere. If the carbon dioxide concentration in the manufacturing equipment is 100 ppm or less, the impact of dissolving carbon dioxide can be ignored.

[0101] (Storage of processing solution) The treatment solution of this embodiment is preferably stored at low temperature and / or protected from light. Storing the solution at low temperature and / or protected from light is expected to have the effect of suppressing decomposition of the oxidizing agent, hypobromite ions, and the like in the treatment solution. Furthermore, the stability of the treatment solution can be maintained by storing the solution in a container whose surface in contact with the solution is made of an organic polymer material, and / or by storing the treatment solution in a container filled with an inert gas to prevent carbon dioxide from entering the treatment solution.

[0102] The semiconductor wafer processing solution of this embodiment can be manufactured by the above manufacturing method. By using the semiconductor wafer processing solution of this embodiment, not only can the wafer processing efficiency per unit time be improved, but it can also be suitably used as a processing solution for, for example, a metal etch-back process in a semiconductor manufacturing process that requires precise etching control for wiring materials. Furthermore, since it has the same effect on metals other than ruthenium, it can be used as an etching solution for metals contained in semiconductor wafers, not limited to ruthenium.

[0103] (Use of processing liquid) The treatment solution of this embodiment can stably etch transition metals adhering to the front, edge, or back surface of a semiconductor wafer at a sufficient etching rate. Furthermore, the flatness of the metal surface can be maintained after etching. In this embodiment, a sufficient etching rate refers to an etching rate that allows the amount of transition metal etched to be controlled by controlling the etching time when etching transition metals for microfabrication in a semiconductor manufacturing process, and maintains flatness after etching. That is, it refers to an etching rate that allows microfabrication of transition metals within a practical time frame for the semiconductor manufacturing process, and maintains the flatness of the metal surface. Specifically, when the target to be etched is ruthenium, this refers to an etching rate of 10 Å / min or higher. When the target to be etched is tungsten, this refers to an etching rate of 50 Å / min or higher, when the target to be etched is molybdenum, this refers to an etching rate of 50 Å / min or higher, when the target to be etched is chromium, this refers to an etching rate of 50 Å / min or higher. When the etching rate of ruthenium, tungsten, molybdenum, or chromium satisfies the above numerical values, the solution can be suitably used in etching processes, residue removal processes, cleaning processes, CMP processes, and the like. When etching of a transition metal is required to be performed at a rate higher than the above-mentioned etching rate, the concentration of hypobromite ions, the concentration of hypochlorite ions, the concentration of the bromine-containing compound, the concentration of the oxidizing agent contained in the treatment liquid, the pH of the treatment liquid, the treatment temperature, the method of contacting the treatment liquid with the wafer, and the like may be appropriately selected.

[0104] As described above, the semiconductor wafer processing solution of this embodiment not only improves wafer processing efficiency per unit time, but can also be suitably used as a processing solution for, for example, a metal etch-back process in a semiconductor manufacturing process that requires precise etching control of wiring materials. Furthermore, since it has the same effect on metals other than ruthenium, it can be used as an etching solution for metals contained in semiconductor wafers other than ruthenium.

[0105] The temperature when etching metal with the treatment solution of this embodiment is not particularly limited, and may be appropriately determined taking into consideration the etching rate of the metal, the stability of the treatment solution, etc. The higher the temperature, the worse the stability of the treatment solution tends to be, so a lower treatment temperature is preferable. On the other hand, the higher the temperature, the faster the etching rate of the metal tends to be. From the viewpoint of achieving both stability of the treatment solution and etching rate, the temperature at which metal is etched is preferably 10°C to 90°C, and 15°C to 90°C is preferable. The temperature is more preferably from 0.degree. C. to 70.degree. C., and most preferably from 20.degree. C. to 60.degree.

[0106] The treatment solution of this embodiment can be suitably used for treating substrates containing a film containing a transition metal. Examples of such substrates include silicon wafers, glass, plastic, and semiconductor substrates other than silicon, each having a film containing a transition metal formed thereon. By using the treatment solution of this embodiment, the film containing a transition metal present on such substrates can be etched at a sufficient rate. This allows the transition metal present on the substrate to be etched (dissolved) and processed and / or removed, thereby enabling the formation of semiconductor elements, wiring, control of the metal film thickness, electrode formation, and the like.

[0107] Specific examples of metals contained in semiconductor wafers to which the treatment solution of this embodiment is applied include Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, and W. These metals can be applied as a single metal species or as an alloy of multiple metal species. Among these metals, metals such as Ru, Rh, Co, Cu, Mo, and W, which are useful as wiring layers, are preferably used. The metals may be formed into films by any method, and methods widely known in the semiconductor manufacturing process, such as CVD, ALD, PVD, sputtering, and plating, can be used.

[0108] The metal may be an intermetallic compound, an ionic compound, or a complex. The metal may be exposed on the surface of the wafer, or may be covered with another metal, a metal oxide film, an insulating film, a resist, or the like. Even if the metal is covered with another material, when the metal comes into contact with the processing solution of this embodiment and dissolution of the metal occurs, both a sufficient etching rate and surface roughness can be achieved.

[0109] For example, the process of using the treatment solution of this embodiment in a metal wiring formation process is as follows: First, a substrate made of a semiconductor (e.g., Si) is prepared. The prepared substrate is subjected to an oxidation treatment to form a silicon oxide film on the substrate. Thereafter, an interlayer insulating film made of a low dielectric constant (Low-k) film is formed, and via holes are formed at predetermined intervals. After the via holes are formed, metal is filled into the via holes by thermal CVD, and a metal film is then formed. By treating this metal film with the treatment solution of this embodiment, it is possible to perform planarization while maintaining a sufficient etching rate.

[0110] The method for bringing the treatment solution of this embodiment into contact with the semiconductor wafer having the metal layer formed thereon is not particularly limited. For example, the treatment solution of this embodiment may be poured onto the semiconductor wafer while the semiconductor wafer is being rotated, or the treatment solution of this embodiment may be brought into contact with the semiconductor wafer by immersing the semiconductor wafer in a container filled with the treatment solution of this embodiment.

[0111] The treatment time when etching metal with the treatment solution of this embodiment is in the range of 0.1 to 120 minutes, preferably 0.3 to 60 minutes, and may be appropriately selected depending on the etching conditions and the semiconductor device used. After using the treatment solution of this embodiment, the treatment solution can be removed by washing the semiconductor wafer surface that has come into contact with the treatment solution with a rinse solution or the like. The rinse solution used after using the treatment solution of this embodiment is not particularly limited, and organic solvents such as alcohol or deionized water can be used. After drying the wafer surface as necessary, the rinsed semiconductor wafer can be used for the next process, such as laminating other wiring materials.

[0112] A second embodiment of the present invention is an inhibitor for RuO4 gas generation, which contains an onium salt composed of an onium ion and a bromine-containing ion, and in which the concentration of the bromine-containing ion in the inhibitor for RuO4 gas generation is 0.1 μmol / L or more and less than 0.001 mol / L. The inhibitor for RuO4 gas generation will be described below.

[0113] (RuO4 gas generation inhibitor) The RuO4 gas generation inhibitor is a composition that suppresses the generation of RuO4 gas by adding it to a liquid for treating ruthenium (hereinafter sometimes referred to as a ruthenium treatment liquid), and refers to a liquid containing an onium salt consisting of an onium ion and a bromine-containing ion.

[0114] The ruthenium treatment solution refers to a solution containing a component that comes into contact with ruthenium and causes a physical or chemical change to the ruthenium. Examples include solutions used in processes for treating ruthenium, such as etching, residue removal, cleaning, and CMP, in semiconductor manufacturing processes. It also includes solutions used to clean ruthenium adhering to the inner walls of chambers, piping, etc., in the various devices used in these semiconductor manufacturing processes.

[0115] Ruthenium treated with a ruthenium treatment solution dissolves, disperses, or precipitates in whole or in part in the ruthenium treatment solution, causing the generation of RuO4 (gas) and / or RuO2 (particles). By adding the RuO4 gas generation inhibitor of this embodiment to the ruthenium treatment solution, the RuO4 present in the ruthenium treatment solution can be suppressed. - and RuO4 2- Anions such as RuO4 - The ion pair formed by the ruthenium-containing ion-pair formed between the ruthenium-containing ion-pair and the onium ion dissolves in the ruthenium treatment solution, thereby suppressing the generation of RuO4 gas and / or RuO2. Furthermore, the bromine-containing ions in the onium salt contained in the RuO4 gas generation inhibitor make it difficult for RuO2 particles to form.

[0116] (onium salts) The RuO gas generation inhibitor of this embodiment contains an onium salt to suppress the generation of RuO gas. The onium salt is composed of an onium ion and a bromine-containing ion. Here, the onium ion is a polyatomic cation formed by the addition of an excess proton (hydrogen cation) to a monoatomic anion. Specific examples of such cations include imidazolium ions, pyrrolidinium ions, pyridinium ions, piperidinium ions, ammonium ions, phosphonium ions, fluoronium ions, chloronium ions, bromonium ions, iodonium ions, oxonium ions, sulfonium ions, selenonium ions, telluronium ions, arsonium ions, stibonium ions, and bismuthonium ions. Among these, ammonium ions, phosphonium ions, and sulfonium ions are suitable as onium ions contained in the onium salt of this embodiment because they are stable in alkaline solutions, the carbon chains and functional groups contained in the onium ions can be easily modified, and the solubility, bulkiness, and charge density can be easily controlled. Furthermore, the bromine-containing ion is an ion containing bromine, and examples thereof include bromite ions, bromate ions, perbromate ions, hypobromite ions, and bromide ions. When the onium ion contained in the onium salt is a polyvalent cation, at least one of the anions contained in the onium salt is a bromine-containing ion. For example, when the onium salt contained in the RuO gas generation inhibitor of this embodiment contains a hexamethonium ion, which is a divalent cation, at least one of the two counter anions may be a bromine-containing ion.

[0117] In order for the onium salt contained in the RuO4 gas generation inhibitor of this embodiment to exhibit its RuO4 gas generation inhibitory ability, the onium salt must dissociate into an onium ion and a bromine-containing ion. -This is because they interact with the ruthenium ions, etc., to suppress the generation of RuO4 gas. Onium salts containing halogen-containing ions are easily dissociated, have excellent solubility, and can stably supply onium ions, and therefore can be used as the onium salt contained in the RuO4 gas generation inhibitor of this embodiment. Among them, onium salts containing bromine-containing ions are more stable and easier to synthesize than onium salts containing chlorine-containing ions or fluorine-containing ions, and therefore high-purity products are industrially available at low cost. In addition, onium salts containing bromine-containing ions have the advantage of containing more onium ions per unit weight than those containing iodine-containing ions. Furthermore, since the bromine-containing ions interact with the ruthenium surface, the anions RuO4 - etc. are kept away from the ruthenium surface. Therefore, the onium salt contained in the RuO4 gas generation inhibitor of this embodiment contains a bromine-containing ion.

[0118] The concentration of the bromine-containing ions in the RuO4 gas generation inhibitor of this embodiment is 0.1 μmol / L or more and less than 0.001 mol / L. If the concentration of the bromine-containing ions is less than 0.1 μmol / L, the interaction with the ruthenium surface becomes weak, and the anions RuO4 -The effect of keeping ions such as bromine away from the ruthenium surface is weakened, tending to make RuO2 particles more likely to form. Furthermore, the concentration of onium ions, which are counter cations of bromine-containing ions, in the ruthenium treatment solution is also reduced, thereby reducing the RuO4 gas generation suppression effect. On the other hand, if the bromine-containing ion concentration is 0.001 mol / L or higher, RuO4 and bromine-containing ions may react, resulting in RuO4 precipitation as RuO2 particles. The precipitation of RuO2 particles is undesirable because it not only reduces the yield in semiconductor manufacturing but also significantly reduces the flatness of the ruthenium surface. Therefore, the bromine-containing ion concentration in the RuO4 gas generation suppressor of this embodiment is preferably 0.5 μmol / L or higher but less than 0.001 mol / L, more preferably 1 μmol / L or higher but less than 0.001 mol / L. These concentration ranges can also be adjusted so that the above concentration ranges are achieved in a solution obtained by mixing the RuO4 gas generation suppressor and the ruthenium treatment solution. When an onium salt is added, only one type may be added, or two or more types may be added in combination. Even when two or more types of onium salts are added, the generation of RuO4 gas can be effectively suppressed as long as the total concentration of bromine-containing ions in the RuO4 gas generation inhibitor is within the above concentration range. Furthermore, the above concentration range is applicable to any of the onium salts represented by formulas (1) and (2).

[0119] The inclusion of the onium salt suppresses the generation of RuO4 gas from the ruthenium treatment solution. - etc. are trapped in the ruthenium treatment solution due to electrostatic interaction with onium ions. Trapped RuO4 - These ions are relatively stable in the treatment solution as ion pairs and do not easily change into RuO4. This prevents the generation of RuO4 gas and RuO2 particles.

[0120] Specific examples of onium ions contained in onium salts include tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, 1-butyl-2,3-dimethylimidazolium ion, 1-hexyl-3-methylimidazolium ion, 1-methyl-3-n-octylimidazolium ion, 1-butyl-1-methylpyrrolidinium ion, 1-ethyl-1-methylpyrrolidinium ion, 1-butyl-1-methylpiperidinium ion, 5-azoniaspiro[4,4]nonane ion, 1-methylpyridinium ion, 1-ethylpyridinium ion, 1-propylpyridinium ion, hexamethonium ion, and decamethonium ion. Onium salts comprise these onium ions and bromine-containing ions such as bromite ion, bromate ion, perbromate ion, hypobromite ion, and bromide ion. Naturally, the onium salt that may be contained in the RuO4 gas generation inhibitor of this embodiment is not limited to the above onium salts.

[0121] As the onium salt having the effect of suppressing the generation of RuO4 gas, those represented by the following formula (1) or (2) are more preferred.

[0122] [ka] (In formula (1), A is nitrogen or phosphorus, and R 1 , R 2 , R 3 , R 4 are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R 1 , R 2 , R 3 , R 4 is an alkyl group, R 1 , R 2 , R 3 , R 4At least one alkyl group among the above has 3 or more carbon atoms. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced with fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced with fluorine or chlorine. X - is a bromine-containing ion.)

[0123] [ka] (In formula (2), R 1 , R 2 , R 3 are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R 1 , R 2 , R 3 is an alkyl group, R 1 , R 2 , R 3 At least one alkyl group among the above has 3 or more carbon atoms. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced with fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced with fluorine or chlorine. X - is a bromine-containing ion.)

[0124] R in the above formula (1) or (2) 1 , R 2 , R 3 , R 4 The alkyl groups may be independently alkyl groups having 1 to 25 carbon atoms without any particular limitation. The larger the number of carbon atoms, specifically, for example, 3 or more, the more easily the onium ion becomes RuO4 -On the other hand, the larger the carbon number, the more easily RuO4 gas is suppressed. Because the onium ion becomes bulky, RuO4 - When electrostatic interaction occurs with the ruthenium salts, the ion pairs that are generated become less soluble in the ruthenium treatment solution, resulting in a precipitate. These precipitates become particles and cause a decrease in the yield of semiconductor devices. Furthermore, the larger the carbon number, the lower the solubility in the ruthenium treatment solution, making it more likely to generate bubbles in the treatment solution. High solubility allows more onium salts to be dissolved in the treatment solution, resulting in a greater suppression effect on RuO4 gas. Conversely, when the carbon number is small, the onium ions and RuO4 - The interaction with the alkyl groups in formula (1) or (2) is weakened, and the RuO4 gas suppression effect is weakened. Therefore, the number of carbon atoms in the alkyl groups in formula (1) or (2) is preferably 1 to 25, more preferably 2 to 10, and most preferably 3 to 6. However, when R in formula (1) 1 , R 2 , R 3 , R 4 is an alkyl group, R 1 , R 2 , R 3 , R 4 At least one of the alkyl groups may have two or more carbon atoms, and R 1 , R 2 , R 3 is an alkyl group, R 1 , R 2 , R 3 At least one of the alkyl groups may have two or more carbon atoms. If the onium salt has an alkyl group with such a carbon number, RuO4 - It can inhibit the generation of RuO4 gas through interaction with the like, and is less likely to form precipitates, so it can be suitably used as an inhibitor of RuO4 gas generation.

[0125] R in the above formula (1) or (2) 1 , R 2 , R 3 , R 4The aryl group independently includes not only aromatic hydrocarbons but also heteroaryls containing heteroatoms, and is not particularly limited, but is preferably a phenyl group or a naphthyl group. Examples of heteroatoms include nitrogen, oxygen, sulfur, phosphorus, chlorine, bromine, and iodine.

[0126] The quaternary and tertiary onium salts represented by the formulas (1) and (2) above are salts of ammonium ions, phosphonium ions, or sulfonium ions that can stably exist in the RuO gas generation inhibitor or ruthenium treatment solution. Generally, the alkyl chain length of these ions can be easily controlled, and it is also easy to introduce allyl or aryl groups. This allows for control of the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surfactant activity, and other properties of the ions, and similar control is also possible for salts composed of these ions. Such salts can be used as the onium salts represented by the formulas (1) and (2) of this embodiment. Examples of ammonium ions contained in the quaternary and tertiary onium salts represented by the formulas (1) and (2) above include the same ammonium ions contained in the quaternary onium bromide described in the third embodiment.

[0127] The quaternary onium salt represented by formula (1) contained in the RuO gas generation inhibitor of this embodiment is preferably an ammonium salt because of its high stability, industrial availability of high-purity products, and low cost. Among these, tetraalkylammonium salts are preferred because of their particularly excellent stability and ease of synthesis. Specific examples include salts formed from tetraethylammonium ions, tetrapropylammonium ions, tetrabutylammonium ions, tetrapentylammonium ions, and tetrahexylammonium ions. Inhibitors containing such onium salts are particularly capable of suppressing the generation of RuO gas and RuO particles during ruthenium treatment.

[0128] The RuO4 gas generation inhibitor of this embodiment can further contain an oxidizer. The oxidizer refers to an agent capable of substantially dissolving ruthenium contained in a semiconductor wafer. Any known oxidizer capable of dissolving ruthenium can be used without any limitation. Examples of the oxidizer include, but are not limited to, halogen oxygen acids, permanganic acid and their salts, hydrogen peroxide, ozone, and cerium (IV) salts. The oxidizer is preferably a halogen oxygen acid or ozone, and more preferably a halogen oxygen acid. Here, halogen oxygen acids include hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, and iodous acid. The oxidizing agent refers to iodic acid, metaperiodic acid, orthoperiodic acid, or their ions. Among halogen oxygen acids, hypochlorous acid, chloric acid, perchloric acid, hypobromous acid, bromic acid, perbromic acid, metaperiodic acid, orthoperiodic acid, or their ions, is preferred. Hypochlorous acid, hypobromous acid, metaperiodic acid, orthoperiodic acid, or their ions, is more preferred. Hypochlorous acid, hypobromous acid, metaperiodic acid, orthoperiodic acid, or their ions, is even more preferred. Since the oxidizing agent can dissolve ruthenium contained in the wafer, suppressing RuO gas generation by containing the oxidizing agent and an onium salt can simultaneously dissolve ruthenium and suppress RuO gas generation. Furthermore, the inclusion of an oxidizing agent promotes the dissolution of ruthenium and the re-dissolution of precipitated RuO particles. Therefore, the RuO4 gas generation inhibitor containing an onium salt and an oxidizing agent can efficiently process ruthenium-containing wafers while suppressing the generation of RuO4 gas and RuO2 particles.

[0129] Among halogen oxygen acids, hypochlorite ions have a high redox potential, so ruthenium dissolved in a solution containing hypochlorous acid will react with RuO4 - Therefore, by further containing hypochlorite ions in the RuO4 gas generation inhibitor of this embodiment, RuO4 -The interaction between the onium ions and the like is more easily maintained, resulting in an enhanced RuO4 gas generation suppression effect. Furthermore, the suppression of RuO4 gas generation suppresses the generation of RuO2 particles. Since high-purity hypochlorite ions suitable for semiconductor manufacturing are relatively easily available, they can be suitably used as an oxidizing agent that may be further contained in the RuO4 gas generation inhibitor of this embodiment. The concentration of hypochlorite ions that may be contained in the RuO4 gas generation inhibitor is preferably 500 mass ppb or more and 20.0 mass% or less. By using a ruthenium treatment solution containing the RuO4 gas generation inhibitor of this embodiment with hypochlorite ions in the above concentration range, it is possible to perform ruthenium treatment while suppressing the generation of RuO4 gas and RuO2 particles.

[0130] (pH of RuO4 gas generation inhibitor) The RuO4 gas generation inhibitor of this embodiment preferably has a pH of 8 or more and 14 or less at 25°C. If the pH is less than 8, the dissolution of ruthenium is limited by the RuO4 - Since the gas generation is more likely to occur via RuO2 or Ru(OH)3 rather than via other anions such as RuO4, the gas suppression effect of onium salts is likely to be reduced. This RuO2 becomes a particle source, and furthermore, at a pH of less than 8, problems such as increased RuO4 gas generation arise. Furthermore, at a pH of more than 14, re-dissolution of RuO2 becomes difficult, resulting in the generation of RuO2 particles. Therefore, in order to fully exert the RuO4 gas generation suppression ability, the pH of the inhibitor is preferably 8 to 14, more preferably 12 to 13. Within this pH range, the dissolved ruthenium dissolves in RuO4. - or RuO4 2- Since it exists as an anion, it easily forms an ion pair with the onium ion contained in the inhibitor, and can effectively suppress the generation of RuO4 gas.

[0131] (Other components of RuO4 gas generation inhibitor) The RuO gas generation inhibitor of this embodiment may optionally contain other additives conventionally used in semiconductor processing solutions, provided that the invention is not impaired. For example, other additives may include acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidizing agents, reducing agents, complexing agents, chelating agents, surfactants, antifoaming agents, pH adjusters, and stabilizers. These additives may be added alone or in combination.

[0132] (Method for suppressing RuO4 gas generation, halogen oxygen acid) The method for suppressing the generation of RuO4 gas includes a step of adding the RuO4 gas generation inhibitor of this embodiment to a ruthenium processing solution. Specifically, for example, the method is for suppressing the generation of RuO4 gas in a ruthenium processing solution used in an etching step, a residue removal step, a cleaning step, a CMP step, etc. in a semiconductor manufacturing process. By adding the RuO4 gas generation inhibitor of this embodiment to the processing solution, the generation of RuO4 gas can be suppressed. Furthermore, when cleaning ruthenium adhering to the chamber inner walls, piping, etc., in each device used in these semiconductor manufacturing processes, the generation of RuO4 gas can be suppressed by using the RuO4 gas generation inhibitor of this embodiment. For example, in the maintenance of a device that forms a Ru film using physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), etc., adding the RuO4 gas generation inhibitor to the cleaning solution used to remove Ru adhering to the chamber, piping, etc. makes it possible to suppress the generation of RuO4 gas during cleaning. According to this method, the generation of RuO4 gas can be suppressed by the above-mentioned mechanism.

[0133] For example, the RuO4 gas generation inhibitor of this embodiment can be used in a ruthenium wiring formation process as follows: First, a substrate made of a semiconductor (e.g., Si) is prepared. The prepared substrate is subjected to an oxidation treatment to form a silicon oxide film on the substrate. Then, an interlayer insulating film made of a low dielectric constant (Low-k) film is formed, and via holes are formed at predetermined intervals. After the via holes are formed, ruthenium is embedded in the via holes by thermal CVD, and a ruthenium film is then formed. This ruthenium film is etched using a ruthenium treatment solution containing the RuO4 gas generation inhibitor, thereby suppressing RuO4 gas generation and achieving planarization. This allows for the formation of highly reliable ruthenium wiring in which the generation of RuO2 particles is suppressed. The ruthenium treatment solution containing the RuO4 gas generation inhibitor can also be used to remove ruthenium adhering to the bevel of a semiconductor wafer.

[0134] The RuO4 gas generation inhibitor of this embodiment can suppress the generation of RuO4 gas not only in the ruthenium treatment solution but also in the solution after ruthenium treatment (hereinafter referred to as ruthenium-containing solution). Here, ruthenium-containing solution means a liquid containing ruthenium even in a small amount. The ruthenium contained in the ruthenium-containing solution is not limited to ruthenium metal, but may be any liquid containing ruthenium element, for example, Ru, RuO4 - , RuO4 2- , RuO4, RuO 2、Examples of ruthenium-containing liquids include waste liquids generated during the semiconductor manufacturing process or chamber cleaning, as well as liquids processed in exhaust gas treatment devices (scrubbers) that capture RuO4 gas. Even trace amounts of ruthenium in a ruthenium-containing liquid can generate RuO2 particles via RuO4 gas, contaminating tanks and piping, and accelerating equipment deterioration due to the oxidation of the particles. Furthermore, RuO4 gas generated from a ruthenium-containing liquid is highly toxic to the human body even at low concentrations. Because ruthenium-containing liquids have various adverse effects on equipment and the human body, they must be safely and quickly treated while suppressing the generation of RuO4 gas. Adding the RuO4 gas generation inhibitor of this embodiment to a ruthenium-containing liquid can suppress the generation of RuO4 gas, thereby not only enabling safe treatment of the ruthenium-containing liquid but also reducing contamination and deterioration of the equipment's tanks and piping.

[0135] The amount of the RuO4 gas generation inhibitor of this embodiment added to the ruthenium treatment solution or ruthenium-containing solution may be determined taking into consideration the amount of ruthenium present in these solutions. The amount of the RuO4 gas generation inhibitor of this embodiment added is not particularly limited, but is preferably 10 to 500,000 by weight, more preferably 100 to 100,000, and even more preferably 1,000 to 50,000, when the amount of ruthenium present in the ruthenium treatment solution or ruthenium-containing solution is taken as 1.

[0136] The pH of the mixture of the RuO4 gas generation inhibitor and the ruthenium treatment liquid or the ruthenium-containing liquid at 25°C is preferably, for example, 7 to 14. To adjust the pH of this mixture, the above-mentioned acids, alkalis, pH buffers, and / or solvents may be added.

[0137] A third embodiment of the present invention is a method for producing a halogen oxyacid, which comprises reacting a bromine salt, an organic alkali, and a halogen to obtain the halogen oxyacid.

[0138] The manufacturing method of this embodiment is characterized by adding a halogen to a solution containing a bromine salt and an organic alkali. The halogen added to the solution containing the organic alkali reacts with the organic alkali to produce a halogen oxyacid and a halide. This allows for a halogen oxyacid solution containing a halide. In this embodiment, unless otherwise specified, the term "halogen oxyacid" refers to a hypohalous acid, a haloous acid, a halogen acid, a perhalogen acid, or an ion thereof. The resulting halogen oxyacid may contain one or more types of hypohalous acid, a haloous acid, a halogen acid, or a perhalogen acid.

[0139] (halogen) In the production method of this embodiment, halogen refers to fluorine, chlorine, bromine, or iodine. These may be added as a gas to a solution containing a bromine salt and an organic alkali, or as a halogen-containing solution to a solution containing a bromine salt and an organic alkali. Either halogen gas or a halogen-containing solution will react with the bromine salt and the organic alkali to form a halogen oxyacid, thereby producing the halogen oxyacid of this embodiment. However, halogen gas is preferred because it is industrially readily available in high purity and easy to handle. Chlorine gas is particularly suitable because it is available in semiconductor-grade high purity at a relatively low cost and can be easily oxidized directly or indirectly to produce a halogen oxyacid, as described below. The rate at which the halogen gas is supplied is not particularly limited and can be determined appropriately taking into account the amount of halogen supplied and the reaction time. Furthermore, halogen gas may be mixed with an inert gas such as nitrogen or argon.

[0140] For example, when the halogen is chlorine, adding chlorine to a solution containing a bromine salt and an organic alkali and reacting the chlorine can produce a halogen oxyacid containing a bromine salt, at least one of hypochlorous acid, chlorous acid, chloric acid, or perchloric acid, and further containing chloride. When the halogen is bromine, adding bromine to a solution containing a bromine salt and an organic alkali and reacting the bromine can produce a halogen oxyacid containing a bromine salt, at least one of hypobromous acid, bromous acid, bromic acid, or perbromic acid, and further containing bromide. When the halogen is iodine, adding iodine to a solution containing a bromine salt and an organic alkali and reacting the bromine salt can produce a halogen oxyacid containing a bromine salt, at least one of hypoiodous acid, iodous acid, iodic acid, or periodic acid, and further containing iodide.

[0141] (organic alkali) In the production method of this embodiment, the organic alkali refers to an organic alkali composed of an organic cation and a hydroxide ion. Such organic alkali does not contain metals that are problematic in semiconductor production. Therefore, by using an organic alkali, the metal content in the resulting halogen oxyacid can be reduced, making it suitable for use in semiconductor production processes. An example of such an organic cation is an onium ion. An onium ion is a polyatomic cation compound formed by the addition of an excess proton (hydrogen cation) to a monoatomic anion. Specific examples of such cations include imidazolium ions, pyrrolidinium ions, pyridinium ions, piperidinium ions, ammonium ions, phosphonium ions, fluoronium ions, chloronium ions, bromonium ions, iodonium ions, oxonium ions, sulfonium ions, selenonium ions, telluronium ions, arsonium ions, stibonium ions, and bismuthonium ions. Among these, ammonium ions, phosphonium ions, and sulfonium ions are stable in alkaline solutions, and the carbon chains and functional groups contained in the onium ions can be easily modified, allowing for easy changes in solubility, bulkiness, and charge density. Since it can be easily controlled, it is suitable as the organic cation contained in the organic alkali of this embodiment. From the viewpoint of industrially inexpensive mass production, the onium ion is more preferably an ammonium ion. Examples of such ammonium ions include tetraalkylammonium ions, and more preferably, tetramethylammonium ions, ethyltrimethylammonium ions, tetraethylammonium ions, tetrapropylammonium ions, and tetrabutylammonium ions. An organic alkali containing an onium ion and a hydroxide ion, i.e., onium hydroxide, can be suitably used as the organic alkali of this embodiment. In addition, an ammonium ion (NH4 + An organic alkali containing 2-hydroxyethyltrimethylammonium or 2-hydroxyethyltrimethylammonium as an organic cation can also be suitably used as the organic alkali in this embodiment.

[0142] Considering the stability of the halogen oxyacid, the pH of the halogen oxyacid is preferably 8 or more and less than 14. The concentration of the organic alkali used in the production is not particularly limited as long as the pH of the produced halogen oxyacid is within the above range, and can be determined taking into consideration the type of organic alkali used and the type and amount of halogen added. For example, the concentration is 0.0001% by mass or more and 30% by mass or less.

[0143] (bromine salt) In this embodiment, the term "bromine salt" refers to a salt containing a bromine atom, such as hypobromite, bromite, bromate, perbromate, or bromide. Examples of bromides include hydrogen bromide, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, ammonium bromide, and onium bromide. The onium bromide referred to here is a compound formed from the onium ion and bromide ion described above. Compounds that generate hypobromous acid or hypobromite ions in the treatment solution can also be used as bromine-containing compounds. Examples of such compounds include, but are not limited to, bromohydantoins, bromoisocyanuric acids, bromosulfamic acids, and bromochloramines. More specific examples of compounds include 1-bromo-3-chloro-5,5-dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin, and tribromoisocyanuric acid.

[0144] The bromine salt may be added as a bromine salt to a solution containing an organic alkali, or as a solution containing a bromine salt to a solution containing an organic alkali, or as bromine gas to a solution containing an organic alkali. For ease of handling in the production process of a halogen oxyacid, the bromine salt is preferably mixed with the solution containing an organic alkali as a bromide or a bromide-containing solution. The solution containing an organic alkali may contain one type of bromine salt, or two or more types may be used in combination. Depending on the convenience of the production process, an organic alkali may be added to the solution containing the bromine salt. Furthermore, a solution containing a bromine salt and an organic alkali may be prepared by simultaneously adding the bromine salt and an organic alkali to an appropriate solvent. In any case, a solution containing a bromine salt and an organic alkali can be obtained.

[0145] In semiconductor manufacturing, contamination with metals or metal ions can reduce yields, so it is desirable that the bromine salt does not contain metals. Among bromine gas and bromine salts, onium bromide is substantially free of metals and can therefore be suitably used as the bromine salt of this embodiment. Among onium bromides, quaternary onium bromide or tertiary onium bromide, or hydrogen bromide, are particularly suitable as the bromine salt of this embodiment because they are industrially readily available and easy to handle.

[0146] Quaternary onium bromides are bromide salts consisting of ammonium ions or phosphonium ions that can exist stably in a solution containing a bromide salt and an organic alkali. Examples of quaternary onium bromides include tetramethylammonium bromide, ethyltrimethylammonium bromide, Examples of suitable amines include tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, methyltriethylammonium bromide, diethyldimethylammonium bromide, trimethylpropylammonium bromide, butyltrimethylammonium bromide, trimethylnonylammonium bromide, decyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, trimethylstearylammonium bromide, decamesonium bromide, phenyltrimethylammonium bromide, benzyltrimethylammonium bromide, dimethylpyrrolidinium bromide, dimethylpiperidium bromide, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylpyridinium bromide. Also useful are compounds in which a proton is added to a tertiary amine, secondary amine, or primary amine. Examples include methylamine hydrobromide, dimethylamine hydrobromide, ethylamine hydrobromide, diethylamine hydrobromide, triethylamine hydrobromide, 2-bromoethylamine hydrobromide, 2-bromoethyldiethylamine hydrobromide, ethylenediamine dihydrobromide, propylamine hydrobromide, butylamine hydrobromide, tert-butylamine hydrobromide, neopentylamine hydrobromide, 3-bromo-1-propylamine hydrobromide, dodecylamine hydrobromide, cyclohexanamine hydrobromide, and benzylamine hydrobromide. Examples of quaternary phosphonium bromides include tetramethylphosphonium bromide, tetraethylphosphonium bromide, tetrapropylphosphonium bromide, tetrabutylphosphonium bromide, tetraphenylphosphonium bromide, methyltriphenylphosphonium bromide, phenyltrimethylphosphonium bromide, and methoxycarbonylmethyl(triphenyl)phosphonium bromide. The tertiary onium bromide is a bromide salt consisting of a sulfonium ion that can be stably present in the processing solution.Examples of tertiary sulfonium bromides include trimethylsulfonium bromide, triethylsulfonium bromide, tripropylsulfonium bromide, tributylsulfonium bromide, triphenylsulfonium bromide, and (2-carboxyethyl)dimethylsulfonium bromide. Among these, quaternary onium bromides, which are bromide salts consisting of ammonium ions, are preferred because they are highly stable, highly pure products are readily available industrially, and are inexpensive.

[0147] The quaternary onium bromide is preferably a tetraalkylammonium bromide, which is particularly stable and easily synthesized. The number of carbon atoms in the alkyl group of the tetraalkylammonium bromide is not particularly limited, and the four alkyl groups may have the same or different carbon atoms. As such alkylammonium bromides, tetraalkylammonium bromides having 1 to 20 carbon atoms per alkyl group are preferred. Among these, tetraalkylammonium bromides having a low alkyl group carbon number are more preferred because of the high number of bromine atoms per weight. Examples include tetramethylammonium bromide, ethyltrimethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, and tetrahexylammonium bromide. Among these, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, and tetrabutylammonium bromide are preferred, with tetramethylammonium bromide being the most preferred. The solution containing a bromine salt and an organic alkali may contain one or more bromine-containing compounds.

[0148] The tetraalkylammonium bromide used in this embodiment may be a commercially available tetraalkylammonium bromide, or may be a tetraalkylammonium bromide produced from tetraalkylammonium ions and bromide ions. The method for producing tetraalkylammonium bromide simply involves mixing an aqueous solution containing tetraalkylammonium hydroxide with an aqueous solution containing bromide ions or a bromine-containing gas that generates bromide ions when dissolved in water.

[0149] Examples of tetraalkylammonium hydroxides used to produce tetraalkylammonium bromide include tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Among these, tetramethylammonium hydroxide or ethyltrimethylammonium hydroxide is more preferred because they have a large number of hydroxide ions per unit weight and are readily available as high-purity products.

[0150] Examples of bromide ion sources that generate bromide ions used to produce tetraalkylammonium bromide include hydrogen bromide, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, ammonium bromide, etc. Among these, hydrogen bromide is preferred because it is substantially free of metals, is readily available industrially, and is readily available as a high-purity product.

[0151] (solvent) The solvent for the solution containing the bromine salt and the organic alkali is not particularly limited, and water or an organic solvent can be used. Naturally, when water is used as the solvent for the solution containing the bromine salt and the organic alkali, the solvent for the resulting halogen oxygen acid is also water.

[0152] Water is most preferably used as the solvent, but water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filtration, various adsorption treatments, etc. is preferred, and pure water or ultrapure water is particularly preferred. Such water can be obtained by known methods widely used in semiconductor manufacturing.

[0153] Furthermore, water and an organic solvent may be used in combination as the solvent. By using water and an organic solvent in combination, oxidation of the transition metal proceeds relatively slowly, thereby suppressing oxidation of wiring and the like in the circuit formation portion. When water and an organic solvent are used in combination, the mass ratio of water to organic solvent (water / organic solvent) may be about 60 / 40 to 99.9 / 0.1.

[0154] (Reaction of bromine salts, organic alkalis, and halogens) The third embodiment of the method for producing a halogen oxyacid involves the reaction of a bromine salt, an organic alkali, and a halogen. When a halogen is added to a solution containing a bromine salt and an organic alkali, it quickly dissolves in the solution and reacts with the organic alkali to produce a hypohalous acid and a halide. The hypohalous acid then reacts with bromide ions, hypobromite ions, bromite ions, bromate ions, or perbromate ions contained in the bromine salt, or with bromine molecules generated from the bromine salt, to produce a new halogen oxyacid. The reaction between the hypohalous acid and the ions or bromine molecules may be any reaction that generates a new halogen oxyacid by adding a halogen to a solution containing a bromine salt and an organic alkali. It may be a redox reaction, a disproportionation reaction, or a radical reaction.

[0155] To explain more specifically, the reaction between a bromide salt, an organic alkali, and a halogen when the bromide salt is tetramethylammonium bromide, the organic alkali is tetramethylammonium hydroxide, and the halogen is chlorine is exemplified as follows: When chlorine gas is blown into an aqueous solution containing tetramethylammonium bromide and tetramethylammonium hydroxide, the tetramethylammonium hydroxide reacts with chlorine to produce hypochlorous acid and chloride. Some of the hypochlorous acid reacts with the bromide ions of the tetramethylammonium bromide in the solution, directly oxidizing the bromide ions to produce hypobromous acid. As a result, an aqueous solution containing hypochlorous acid, hypobromous acid, chloride (tetramethylammonium chloride), unreacted tetramethylammonium bromide, and tetramethylammonium hydroxide is obtained. That is, an aqueous solution of halogen oxygen acids containing two halogen oxygen acids (hypochlorous acid and hypobromous acid) is obtained. Furthermore, if the number of moles of chlorine molecules is smaller than the number of moles of tetramethylammonium bromide in a solution containing a bromine salt and an organic alkali, an aqueous solution containing hypobromous acid, chloride (tetramethylammonium chloride), unreacted tetramethylammonium bromide, and tetramethylammonium hydroxide is obtained.

[0156] As another specific example, the reaction between a bromine salt, an organic alkali, and a halogen when the bromine salt is tetramethylammonium hypobromite, the organic alkali is tetramethylammonium hydroxide, and the halogen is chlorine is as follows: When chlorine gas is blown into an aqueous solution containing tetramethylammonium hypobromite and tetramethylammonium hydroxide, the tetramethylammonium hydroxide reacts with chlorine to produce hypochlorous acid and chloride. A portion of the hypochlorous acid reacts with the hypobromous acid of the tetramethylammonium hypobromite in the solution to produce chlorous acid and bromous acid, respectively. As a result, an aqueous solution containing hypochlorous acid, chlorous acid, bromous acid, unreacted tetramethylammonium hypobromite, and tetramethylammonium hydroxide is obtained. That is, an aqueous solution containing halogen oxygen acids containing four types of halogen oxygen acids (hypobromous acid, chlorous acid, bromous acid, and hypobromous acid) is obtained.

[0157] The semiconductor processing solution containing a halogen oxyacid produced by this manufacturing method is a processing solution that has excellent chemical stability, can stably etch transition metals at a sufficient etching rate, and can maintain the flatness of the transition metal surface after etching. In particular, a processing solution containing hypobromite ions at a concentration of 0.1 μmol / L or more but less than 0.001 mol / L has particularly excellent chemical stability, and can stably etch transition metals at a sufficient etching rate and maintain the flatness of the transition metal surface after etching, as described above. Therefore, as described in the first embodiment, it can be suitably used as a processing solution for semiconductor wafers containing transition metals.

[0158] Thus, when a treatment solution is prepared using onium hydroxide as the organic alkali, bromine as the halogen, and onium bromide as the bromine salt, the bromine reacts with the onium hydroxide to produce a treatment solution containing hypobromite ions and bromine-containing ions. Furthermore, when a treatment solution is prepared using onium hydroxide as the organic alkali, chlorine as the halogen, and onium bromide as the bromine salt, the chlorine reacts with the onium hydroxide to produce hypochlorite ions and chloride ions in the treatment solution, and the hypochlorite ions further react with the bromine salt. This results in a treatment solution containing hypobromite ions and bromine-containing ions. The resulting treatment solution can be used not only as a treatment solution for semiconductor wafers but also as a RuO gas generation inhibitor. Examples of bromine-containing ions include those exemplified in the second embodiment.

[0159] The concentration of the halogen oxyacid produced by this production method is not particularly limited, but it is preferable that the concentration of hypochlorite ions or bromine-containing ions is 0.1 μmol / L or more and less than 0.001 mol / L. If the concentration of the halogen oxyacid is within the above range, the resulting halogen oxyacid is particularly suitable for use as the semiconductor wafer processing solution and / or RuO gas generation inhibitor described above. If the concentration of the halogen oxyacid produced by this production method is lower than the above range, the concentration can be increased by, for example, increasing the amount of halogen reacted with the organic alkali or adding a halogen oxyacid salt. If the concentration of the halogen oxyacid is higher than the above range, it can be diluted with, for example, an appropriate solvent. In order to etch the transition metal stably at a sufficient rate and maintain the flatness of the metal surface after etching, the concentration of the halogen oxygen acid is preferably 0.1 μmol / L or more and less than 0.001 mol / L, more preferably 1 μmol / L or more and less than 0.001 mol / L, even more preferably 10 μmol / L or more and less than 0.001 mol / L, and most preferably 50 μmol / L or more and less than 0.001 mol / L. The halogen oxyacid may be contained alone or in combination of two or more. When two or more types are contained, the concentration of each halogen oxyacid is preferably 0.1 μmol / L or more and less than 0.001 mol / L.

[0160] (Other additives) The halogen oxyacid produced by the method for producing a halogen oxyacid according to the third embodiment may optionally contain other additives conventionally used in semiconductor processing solutions, provided that the purpose of the present invention is not impaired. For example, other additives may include acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidizing agents, reducing agents, complexing agents, chelating agents, surfactants, antifoaming agents, pH adjusters, and stabilizers. These additives may be added alone or in combination.

[0161] Due to these additives and for reasons of manufacturing convenience, the halogen oxyacid of this embodiment may contain alkali metal ions, alkaline earth metal ions, etc. For example, sodium ions, potassium ions, calcium ions, etc. may be contained. However, since these alkali metal ions and alkaline earth metal ions, etc., if remaining on the semiconductor wafer, have adverse effects on semiconductor elements (such as reduced semiconductor wafer yield), it is preferable that their amount be small, and in fact, it is preferable that they are not contained at all. Therefore, for example, as a pH adjuster, it is preferable to use an organic alkali such as ammonia, amine, choline, or tetraalkylammonium hydroxide, rather than an alkali metal hydroxide such as sodium hydroxide or an alkaline earth metal hydroxide.

[0162] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1% by mass or less, more preferably 0.7% by mass or less, even more preferably 0.3% by mass or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0163] Furthermore, when producing a halogen oxyacid by the production method described in this embodiment, the conditions and measures described above for the semiconductor wafer treatment solution and the RuO gas generation inhibitor can be appropriately selected and used. For example, the above-mentioned conditions and measures can be suitably used to prevent dissolution of carbon dioxide, inclusion of amines, inclusion of metals, decomposition by light, etc.

[0164] As described above, the method for producing a halogen oxyacid according to this embodiment allows for the simple and efficient production of a halogen oxyacid, particularly a semiconductor wafer treatment solution containing hypobromite ions and bromine-containing ions. Furthermore, this method prevents the inclusion of metals, such as sodium, potassium, and calcium, which are problematic in semiconductor manufacturing. This method significantly reduces the amount of metal contamination compared to methods for producing a halogen oxyacid by ion exchange using an aqueous solution of a sodium, potassium, or calcium salt of a hypohalous acid as a starting material. Furthermore, this method does not require the periodic regeneration of ion exchange resins required in ion exchange methods, and allows for continuous production, thereby improving the productivity of the treatment solution and reducing production costs. Therefore, this method for producing a halogen oxyacid according to this embodiment is particularly suitable for use as a semiconductor wafer treatment solution and / or a halogen oxyacid used as an inhibitor of RuO gas generation. [Example]

[0165] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0166] (Preparation of tetramethylammonium hypochlorite ((CH3)4NClO3) or tetramethylammonium bromate ((CH3)4NBrO3)) A saturated solution was obtained by adding sodium chlorate (Fujifilm Wako Pure Chemical Industries, Ltd.) or sodium bromate (Fujifilm Wako Pure Chemical Industries, Ltd.) to ion-exchanged water and storing it in a refrigerator for 24 hours. The precipitated sodium bromate was recovered by filtration. The recovered sodium bromate was dissolved in ultrapure water and analyzed using an ion chromatography analyzer. The CO3 - , S O4 - , Br - By analyzing the water, it was confirmed that the impurities Na2CO3, Na2SO4, and NaBr were reduced. By repeating the above purification process, CO3 - , S O4 - , Br -It was confirmed that the respective concentrations were 500 ppb or less, and purified sodium chlorate or sodium bromate was obtained.

[0167] Next, a strong acid ion exchange resin (Amberlite IR-120BNa, Organo Corporation) was placed in a glass column (AsOne Corporation, Biocolumn CF-50TK) with an inner diameter of approximately 45 mm. 00 mL was added. Then, 1 L of 1 N hydrochloric acid (Fujifilm Wako Pure Chemical Industries, Ltd., for volumetric analysis) was passed through the ion exchange resin column to exchange the ion exchange resin into the hydrogen form, and 1 L of ultrapure water was passed through to wash the ion exchange resin. Furthermore, 2 L of 2.38% tetramethylammonium hydroxide solution was passed through the ion exchange resin that had been exchanged into the hydrogen form, and the ion exchange from the hydrogen form to the tetramethylammonium form was performed. After the ion exchange, 1 L of ultrapure water was passed through to wash the ion exchange resin.

[0168] 6.4 g of purified sodium chlorate or sodium bromate was placed in a fluororesin container and 93.6 g of ultrapure water was added to prepare a 6.4 mass% sodium chlorate or sodium bromate aqueous solution. The prepared sodium chlorate or sodium bromate aqueous solution was passed through an ion exchange resin that had been converted to a tetramethylammonium form. The recovered tetramethylammonium chlorate or bromate was analyzed for Na concentration using a high-frequency inductively coupled plasma atomic emission spectroscopy (iCAP6500DuO, Thermo Scientific) to confirm that ion exchange was sufficient. If insufficient, the above procedure was repeated to obtain a 10 mass% tetramethylammonium chlorate or bromate solution with a Na concentration of 500 ppb or less. The resulting solution was heat-treated to obtain tetramethylammonium chlorate or bromate powder. The tetramethylammonium chlorate or bromate powder was added to the treatment solution to generate chlorate ions or bromate ions.

[0169] (Other reagents) The reagents used in the examples and comparative examples are as follows: Tetramethylammonium bromide ((CH3)4NBr): Tokyo Chemical Industry Co., Ltd. 15 wt% HCl: manufactured by Kanto Chemical Co., Ltd. (prepared by diluting 35 wt% HCl with ultrapure water) 1 mol / L tetramethylammonium hydroxide (TMAH): Tokuyama Corporation (prepared by diluting 25 wt% TMAH with ultrapure water)

[0170] (Method for measuring hypobromite ion and hypochlorite ion concentrations) The concentrations of hypobromite ions and hypochlorite ions were measured using an ultraviolet-visible spectrophotometer (UV-2600, manufactured by Shimadzu Corporation). Calibration curves were prepared using aqueous solutions of hypobromite ions and hypochlorite ions with known concentrations, and the concentrations of hypobromite ions and hypochlorite ions in the produced treatment solution were determined.

[0171] (Method for measuring the concentration of anionic species) The concentration of anion species in the semiconductor wafer processing solution was measured using an ion chromatography analyzer (DIONEX INTEGRION HPLC, manufactured by Thermo Scientific). KOH was used as the eluent, and the solution was passed through at a flow rate of 1.2 mL / min. The column used was an anion analysis column for hydroxide-based eluents (AS15, manufactured by Thermo Scientific), and the column temperature was set to 30°C. After removing background noise, the anion species in the treated solution were quantified using an electric conductivity detector.

[0172] (pH measurement method) The pH of 10 mL of the treatment solution prepared in the Examples and Comparative Examples was measured using a desktop pH meter (LAQUA F-73, manufactured by Horiba, Ltd.) The pH measurement was carried out after the treatment solution was prepared and stabilized at 25°C.

[0173] (Preparation of semiconductor wafers for metal etching performance evaluation) The ruthenium, molybdenum, tungsten, and chromium films used in the examples and comparative examples were formed as follows. The ruthenium, molybdenum, and chromium films were obtained by forming an oxide film on a silicon wafer using a batch-type thermal oxidation furnace, and then depositing a 100 Å film of ruthenium, a 500 Å film of molybdenum, or a 500 Å film of chromium on top of that using a sputtering method. The tungsten film was obtained by similarly forming a thermal oxide film and then depositing a 500 Å film of tungsten using a CVD method. The sheet resistance was measured using a four-point probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted to film thickness, which was used as the metal film thickness before etching.

[0174] (Evaluation of metal etching performance) 60 mL of the treatment solution for this example was prepared in a fluororesin container with a lid (94.0 mL PFA container, manufactured by AsOne Corp.). Each semiconductor wafer piece for evaluation, measuring 10 × 20 mm, was immersed in the treatment solution for 1 minute at the treatment temperature (30°C to 50°C) listed in Table 1, and the etching rate was calculated by dividing the change in film thickness before and after treatment by the immersion time.

[0175] (Evaluation of etching rate stability) The etching rate stability evaluation was carried out as follows. The etching rate of the produced treatment solution was evaluated every 10 hours according to the "Evaluation of Metal Etching Performance" described above. The time during which the obtained etching rate varied within ±20% of the etching rate immediately after production was taken as the etching rate stabilization time, and was classified according to the following scale. The etching rate stabilization time was ranked A to D in order of longest, with ratings A to C being acceptable levels and rating D being unacceptable. A: The etching rate remains stable for 100 hours or more, making it particularly suitable for use. B: The etching rate remains stable for 50 hours or more, making it suitable for use. C: The etching rate remains stable for 10 hours or more, making it suitable for use. D: The etching rate stabilizes for less than 10 hours.

[0176] (Surface evaluation after etching (flatness evaluation)) The metal surface was observed before and after etching using a field emission scanning electron microscope (JSM-7800F Prime, manufactured by JEOL Ltd.) to check for the presence or absence of surface roughness and evaluate it according to the following criteria: A to D is graded in order of least surface roughness (maintained flatness), with grades A to C being acceptable levels and grade D being unacceptable. A: No surface roughness is observed B: Some surface roughness is observed C: Roughness is visible across the entire surface, but the roughness is shallow. D: Roughness is observed over the entire surface, and the roughness is deep.

[0177] (Metal Determination Method in Halogen Oxygen Acids) High-resolution inductively coupled plasma mass spectrometry was used to measure the metal concentrations in the halogen-oxygen acids. Ultrapure water and 1.25 mL of high-purity nitric acid (Ultrapure-100 nitric acid, Kanto Chemical Co., Ltd.) were added to a 25 mL polyfluoroalkyl ether (PFA) measuring flask (AsOne, PFA measuring flask). Then, a pipette (AsOne, Pipetman) was used to measure the metal concentrations. Using a P1000 pipette and a fluororesin pipette tip (AsOne, fluororesin pipette tip), 0.25 mL of halogen oxyacid was collected and added to a PFA volumetric flask and stirred. The sample was then diluted with ultrapure water 10-100 times depending on the halogen oxyacid concentration. Furthermore, the metal content was quantified using a calibration curve method using a high-resolution inductively coupled plasma mass spectrometer (ThermoFisher Scientific, Element 2). To confirm the sensitivity due to the matrix, impurities were added to the measurement solution to a concentration of 2 ppb. The measurement conditions were: RF power 1500 W, argon gas flow rate 15 L / min for plasma gas, 1.0 L / min for auxiliary gas, and 0.7 L / min for nebulizer gas.

[0178] Example 1 (Method of manufacturing a treatment solution containing tetramethylammonium hypobromite) (Preparation of a solution containing bromine salt and organic alkali) Tetramethylammonium bromide (14.6 g; 0.095 mol) and tetramethylammonium hydroxide (18.2 g; 0.190 mol) were placed in a 2 L glass three-neck flask (Cosmos Bead Co., Ltd.), and ultrapure water was added to prepare 1 L of a solution containing bromide and an organic alkali with a pH of 13.3.

[0179] (Reaction process of a solution containing bromine salt and organic alkali with a halogen) Next, a rotor (AsOne, 30 mm long x 8 mm diameter) was placed in a three-neck flask, and a thermometer and thermometer protection tube (Cosmos Bead, bottom-sealed type) were inserted into one opening. The other opening was connected to a chlorine gas cylinder and a nitrogen gas cylinder. The tip of a PFA tube (Flon Industries, F8011-02) was immersed in the bottom of the solution, and the remaining opening was connected to a gas washing bottle (AsOne, model number 2450 / 500) filled with 5% by mass sodium hydroxide aqueous solution. Nitrogen gas was flowed through the PFA tube at 200 sccm for 20 minutes to expel carbon dioxide from the gas phase. Then, a magnetic stirrer (AsOne, C-MAGHS10) was placed at the bottom of the three-neck flask and rotated at 300 rpm. While the outer periphery of the three-neck flask was cooled with ice water, chlorine gas (Fujiox, specified purity 99.4%) was supplied at 200 sccm for 10.6 minutes (total chlorine supply amount 0.095 mol). The liquid temperature during the reaction was 15°C.

[0180] The above reaction yielded a halogen oxygen acid containing 0.095 mol / L tetramethylammonium hypobromite solution (further containing 0.19 mol / L tetramethylammonium chloride and 0.01 mol / L tetramethylammonium hydroxide). The halogen oxygen acid obtained by the above method was diluted 1 / 100 by mixing it with ultrapure water, 15 wt% HCl, and 1 mol / L tetramethylammonium hydroxide (TMAH), to obtain 100 mL of a treatment solution with the composition listed in Table 1.

[0181] (Evaluation of processing solution) The hypohalite ion concentration, anion species concentration, and pH of the resulting treatment solution were measured using the methods described above. The resulting treatment solution was then evaluated for metal etching performance, etching rate stability, and post-etching surface properties using the methods described above. The results are shown in Tables 2 and 3.

[0182] <Examples 2 to 12> The concentrations of the bromine salt and organic alkali and the supply amount of chlorine gas were appropriately adjusted, and a halogen oxyacid-containing treatment solution shown in Table 1 was obtained in the same manner as in Example 1 (method for producing a treatment solution containing tetramethylammonium hypobromite). The treatment solution obtained was evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0183] <Examples 13 to 16> The concentrations of the bromine salt and organic alkali and the amount of chlorine gas supplied were appropriately adjusted, and a halogen oxyacid was obtained in the same manner as in Example 1 (method for producing a treatment solution containing tetramethylammonium hypobromite). However, in Example 15, the flask was heated and chlorine gas was supplied at a liquid temperature of 45°C to generate bromite ions. The obtained halogen oxyacid was diluted 1 / 100 by mixing with tetramethylammonium bromate, ultrapure water, 15 wt% HCl, and 1 mol / L TMAH, to obtain 100 mL of a treatment solution with the composition listed in Table 1. The obtained treatment solution was evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0184] Example 17 (Production of treatment solution containing tetramethylammonium hypobromite and tetramethylammonium hypochlorite) Tetramethylammonium hydroxide (109.4 g) was placed in a 2 L three-neck glass flask, and ultrapure water was added to prepare 0.99 L of a solution containing a bromine salt and an organic alkali with a pH of 14.1. The reaction was carried out in the same manner as in Example 1 (reaction process of a solution containing a bromine salt and an organic alkali with a halogen), except that the supply time of chlorine gas to the solution containing a bromine salt and an organic alkali was 66.6 minutes (total chlorine supply amount: 0.595 mol). The liquid temperature during the reaction was 15°C.

[0185] The above reaction yielded a 0.595 mol / L tetramethylammonium hypochlorite solution (further containing 0.595 mol / L tetramethylammonium chloride and 0.01 mol / L tetramethylammonium hydroxide). The liquid temperature during the reaction was 15°C. 14.6 g of tetramethylammonium bromide was added to the tetramethylammonium hypochlorite solution obtained by the above method, and 0.095 mol / L hypobromite ions were generated by oxidizing the bromide ions with hypochlorite ions. The solution was then diluted 1 / 100 by mixing ultrapure water, 15 wt% HCl, and 1 mol / L TMAH to obtain 100 mL of a treatment solution with the composition listed in Table 1. The resulting treatment solution was evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0186] Example 18 Tetramethylammonium bromide (14.6 g; 0.095 mol) and tetramethylammonium hydroxide (109.4 g; 1.20 mol) were placed in a 2 L glass three-neck flask, and ultrapure water was added to prepare 0.99 L of a solution containing a bromine salt and an organic alkali with a pH of 14.1. The reaction was carried out in the same manner as described in Example 1 (reaction process of a solution containing a bromine salt and an organic alkali with a halogen), except that the supply time of chlorine gas to the solution containing a bromine salt and an organic alkali was 66.6 minutes (total chlorine supply amount: 0.595 mol). The liquid temperature during the reaction was 15°C.

[0187] The above reaction produced 0.095 mol / L tetramethyl hypobromite and 0.595 mol / L tetramethylammonium hypochlorite (further containing 0.595 mol / L tetramethylammonium chloride and 0.01 mol / L tetramethylammonium hydroxide), yielding a solution containing a halogen oxyacid. The solution temperature during the reaction was 15°C. The resulting solution containing a halogen oxyacid was diluted 1 / 100 by adding tetramethylammonium bromate, ultrapure water, 15 wt% HCl, and 1 mol / L TMAH to obtain 100 mL of a treatment solution with the composition listed in Table 1. The resulting treatment solution was evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0188] <Comparative Examples 1 to 6> The treatment liquid shown in Table 1 was obtained in the same manner as in Example 1. However, in Comparative Example 1, the bromine salt Chlorine was supplied to an organic alkali containing no bromide, and the organic alkali and chlorine were reacted. In Comparative Example 4, a treatment solution was obtained by dissolving bromide in an organic alkali. The treatment solution obtained was evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0189] [Table 1]

[0190] [Table 2]

[0191] [Table 3]

[0192] The symbol "-" in Table 1 indicates that the corresponding ion or oxidizing agent was not present in the treatment solution (the same applies to Tables 4, 6, and 8). The symbol "No data" in Tables 2 and 3 indicates that etching did not proceed with the treatment solution, so that the etching rate stability and flatness could not be evaluated, and therefore no data was available. As shown in Tables 2 and 3, when the treatment solutions shown in Comparative Examples 1 to 6 were used, the effects of satisfying all of the requirements for etching rate, stability, and flatness were not achieved. On the other hand, the treatment solutions of the present embodiment shown in Examples 1 to 16 exhibited sufficient etching rate and etching rate stability, and also resulted in satisfactory surface flatness after etching.

[0193] <Examples 19 to 27 and Comparative Examples 7 to 8> (Manufacturing RuO4 gas generation inhibitor) A 100 mL fluororesin container was mixed with 0.095 mol / L aqueous tetramethylammonium hypochlorite solution prepared according to the method described in Example 1, tetramethylammonium bromate powder, tetrapropylammonium chloride (Tokyo Chemical Industry Co., Ltd.), hexyltrimethylammonium chloride (Tokyo Chemical Industry Co., Ltd.), n-octyltrimethylammonium chloride (Tokyo Chemical Industry Co., Ltd.), hexamethonium chloride dihydrate (Tokyo Chemical Industry Co., Ltd.), ultrapure water, 15 wt% HCl, and 1 mol / L NaOH to obtain 30 mL of RuO4 gas generation inhibitors with the compositions listed in Tables 4 to 7. However, in Example 25, the flask was heated to generate bromite ions, and chlorine gas was supplied at a liquid temperature of 45°C. The concentrations of hypobromite ions and hypochlorite ions, the concentration of anionic species, and pH in the obtained RuO4 gas generation inhibitors were measured using the above methods.

[0194] (Production of liquid for processing ruthenium) Sodium hypochlorite (NaClO; manufactured by Wako Pure Chemical Industries, Ltd.) and ultrapure water were added to a 100 mL fluororesin container, and the pH was adjusted to the values ​​shown in Tables 4 to 7 using a 15% by mass HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution, thereby obtaining 30 mL of a solution for treating ruthenium.

[0195] (Quantitative analysis of RuO4 gas) First, the RuO gas generation inhibitor and the solution for treating ruthenium, prepared according to the above procedure, were mixed to obtain 60 mL of a mixed solution. Next, 10 mL of the mixed solution having the composition described in Examples 19 to 27 and Comparative Examples 7 to 8 was placed in an 85 mL glass sealed container, and then a silicon wafer (5 × 5 mm, Ru film thickness 20 nm; Ru amount 5.4 × 10 -8 The wafer was immersed in the solution of 1000 mol of Ru at 25° C. for 15 minutes. The Ru film thickness was measured by XRF to confirm that all of the Ru on the wafer had dissolved. Nitrogen gas was then flowed into the sealed container at 300 mL / min for 15 minutes. The RuO4 gas generated during the immersion of the ruthenium-coated silicon wafer was sequentially absorbed into gas trapping solutions 4 and 5, as shown in Figure 1. Gas trapping solutions 4 and 5 were prepared using a 1 mol / L aqueous solution of tetramethylammonium hydroxide (TMAH). Next, 10 mL of each of gas trapping solutions 4 and 5 was taken, and 20 mL of hydrochloric acid and ultrapure water were added to bring the total volume to 100 mL. The mixture was then allowed to stand for 24 hours to obtain a test solution. The test solution was analyzed by ICP-MS (Agilent Technologies ICP-MS7900, Ru detection m / z = 101) to quantify Ru. Since Ru was not detected in gas trapping solution 5, the amount of Ru absorbed in gas trapping solution 4 was used as the RuO4 gas quantification value. The amount of Ru in Tables 5 and 7 is calculated by dividing the weight of Ru in the RuO4 gas absorbing solution by the area of ​​the Ru-coated wafer.

[0196] [Table 4]

[0197] [Table 5]

[0198] [Table 6]

[0199] [Table 7]

[0200] The results in Tables 4 to 7 show that the generation of RuO4 gas can be suppressed by adding the RuO4 gas generation inhibitor of the present invention to a solution for treating ruthenium. This indicates that the RuO4 gas generation inhibitor of the present invention can be suitably used for treating ruthenium.

[0201] The metal amounts contained in the produced halogen oxyacids were determined as follows. The metals in the halogen oxyacids produced in Examples 1, 14, 17, and 18, and the following Reference Examples 1 and 2, were measured by the above-mentioned method (Metal Determination Method in Halogen Oxyacid). The results of the determination of the metal amounts contained in the produced halogen oxyacids are shown in Table 8.

[0202] (Production of halogen oxygen acids by ion exchange) <Pretreatment of ion exchange resin; Preparation of hydrogen-type ion exchange resin> 200 mL of sodium-type strongly acidic ion exchange resin (Amberlite IR-120BNa, Organo Corporation) was placed in a glass column (AsOne Biocolumn CF-50TK) with an inner diameter of approximately 45 mm. Then, 1 L of 1N hydrochloric acid (Wako Pure Chemical Industries, Ltd., for volumetric analysis) was passed through the ion exchange resin column to exchange it for hydrogen type, and 1 L of ultrapure water was passed through to wash the ion exchange resin. <(a) Process> Furthermore, 1 L of 10% tetramethylammonium hydroxide solution was passed through 209 mL of the hydrogen-type ion-exchange resin to exchange the hydrogen-type ion into the tetramethylammonium-type ion. After the ion exchange, 1 L of ultrapure water was passed through the ion-exchange resin to wash it. <(b1) Process> 125 g of 9% sodium hypobromite aqueous solution (Kanto Chemical, Shika Grade 1) was placed in a 2 L fluororesin container, and 875 g of ultrapure water was added to prepare a 1.1 mass % sodium hypobromite aqueous solution. The prepared sodium hypobromite aqueous solution was passed through the ion exchange resin exchanged to the tetramethylammonium form in step (a) to obtain a tetramethylammonium hypobromite aqueous solution. Ultrapure water and a tetramethylammonium hydroxide solution were added to the obtained halogen oxygen acid to prepare a treatment solution (pH 12.0) containing 0.1 mmol / L tetramethylammonium hypobromite. <(b2) Process> 15.6 g of sodium hypochlorite pentahydrate (Wako Pure Chemical Industries, Ltd., special grade reagent) was placed in a 2 L fluororesin container, and 984 g of ultrapure water was added to prepare a 7.1 mass % sodium hypochlorite aqueous solution. The prepared sodium hypochlorite aqueous solution was passed through the ion exchange resin exchanged to the tetramethylammonium form in step (a) to obtain a tetramethylammonium hypochlorite aqueous solution. Ultrapure water and a tetramethylammonium hydroxide solution were added to the obtained halogen oxygen acid to prepare a treatment solution (pH 12.0) containing 0.1 mmol / L tetramethylammonium hypochlorite.

[0203] <Reference example 1> 0. Produced by step (b1) of the above (Production of halogen oxyacid by ion exchange). A treatment liquid (pH 12.0) containing 1 mmol / L tetramethylammonium hypobromite and an aqueous tetramethylammonium hydroxide solution (pH 12.0) were mixed to obtain halogen oxygen acids containing hypobromous acid shown in Table 8.

[0204] <Reference example 2> A treatment liquid (pH 12.0) containing 0.1 mmol / L tetramethylammonium hypobromite produced in step (b1) of the above (Production of halogen oxyacids by ion exchange), a treatment liquid (pH 12.0) containing 0.1 mmol / L tetramethylammonium hypochlorite produced in step (b2), and an aqueous tetramethylammonium hydroxide solution (pH 12.0) were mixed to obtain halogen oxyacids containing hypobromous acid and hypochlorous acid as shown in Table 8.

[0205] [Table 8]

[0206] The etching rates of Ru were almost the same for the treatment solutions containing hypohalous acid obtained in Examples 1, 14, 17, 18, and 26 and 27. On the other hand, the metals (Na, K, Al) contained in the treatment solutions were less than 1 ppb in Examples 1, 14, 17, and 18, whereas the values ​​in Reference Examples 1 and 2 were much higher.

[0207] The above results demonstrate that the halogen oxyacid produced by the method for producing a halogen oxyacid according to the third embodiment of the present invention can etch ruthenium at a sufficient rate and has an extremely low metal content. [Explanation of symbols]

[0208] 1. Ru-coated silicon wafer 2 Processing liquid 3 N2 gas inlet 4 Gas trap liquid 1 5 Gas trap liquid 2 6 exhaust pipe

Claims

1. A semiconductor processing solution containing hypobromite ions, wherein the concentration of the hypobromite ions is 0.1 μmol / L or more and less than 0.001 mol / L, and the semiconductor processing solution further contains at least one anion species selected from the group consisting of chlorate ions, chlorite ions, chloride ions, bromate ions, bromite ions, and bromide ions.

2. The semiconductor processing solution according to claim 1 , wherein the semiconductor comprises a transition metal.

3. 3. The semiconductor processing solution according to claim 1, further comprising an oxidizing agent, the oxidation-reduction potential of which exceeds the oxidation-reduction potential of a hypobromite ion / bromide ion system.

4. 4. The semiconductor processing solution according to claim 3, wherein the oxidizing agent is at least one oxidizing agent selected from the group consisting of hypochlorite ions, ozone, orthoperiodate ions, and metaperiodate ions.

5. The semiconductor processing solution according to any one of claims 1 to 4, further comprising a tetraalkylammonium ion.

6. 6. The semiconductor processing solution according to claim 1, wherein the pH of the processing solution is 8 or more and 14 or less.

7. RuO, including onium salts consisting of an onium ion and a bromine-containing ion ４ A gas generation inhibitor, comprising the RuO ４ The gas generation inhibitor has a bromine-containing ion concentration of 0.1 μmol / L or more and less than 0.001 mol / L, ４ Gas generation inhibitor.

8. The RuO according to claim 7, wherein the onium salt is a quaternary onium salt represented by formula (1) or a sulfonium salt represented by formula (2): ４ Gas generation inhibitor. 【Chemistry 1】 【Chemistry 2】 (In formula (1), A is nitrogen or phosphorus, and R １ , R ２ , R ３ , R ４ are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R １ , R ２ , R ３ , R ４ is an alkyl group, R １ , R ２ , R ３ , R ４ At least one alkyl group has 3 or more carbon atoms. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine. In formula (2), R １ , R ２ , R ３ are independently an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R １ , R ２ , R ３ is an alkyl group, R １ , R ２ , R ３ At least one alkyl group among the above has 3 or more carbon atoms. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced with fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced with fluorine or chlorine. X － is a bromine-containing ion.)

9. 9. The RuO of claim 8, wherein the quaternary onium salt is a tetraalkylammonium salt. ４ Gas generation inhibitor.

10. The RuO according to any one of claims 7 to 9, wherein the bromine-containing ion is a bromite ion, a bromate ion, a perbromate ion, a hypobromite ion, or a bromide ion. ４ Gas generation inhibitor.

11. The RuO according to any one of claims 7 to 10, further comprising an oxidizing agent. ４ Gas generation suppression Agent.

12. The RuO according to claim 11, wherein the oxidizing agent is hypochlorite ions, and the concentration of the hypochlorite ions is 500 ppb by mass or more and 20.0% by mass or less. ４ Gas generation inhibitor.

13. A method for producing a halogen oxyacid, comprising reacting a bromine salt, an organic alkali, and a halogen to obtain the halogen oxyacid, wherein the concentration of the halogen oxyacid is 0.1 μmol / L or more and less than 0.001 mol / L.

14. 14. The method for producing a halogen oxygen acid according to claim 13, wherein the organic alkali is onium hydroxide.

15. 15. The method for producing a halogen oxygen acid according to claim 13 or 14, wherein the halogen is chlorine.

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