RuO4 gas generation inhibitor and method for inhibiting RuO4 gas generation

Abstract

Provided is a RuO4 gas generation inhibitor that can suppress RuO4 gas generation when a semiconductor wafer containing ruthenium is brought into contact with a processing solution under alkaline conditions. [Solution] We provide a RuO4 gas generation inhibitor for suppressing RuO4 gas generation when a processing solution is brought into contact with a ruthenium-containing semiconductor wafer in a semiconductor formation process, the inhibitor comprising an onium salt consisting of an onium ion and a bromine-containing ion, and a method for suppressing RuO4 gas generation by adding the inhibitor to a ruthenium processing solution or a ruthenium-containing solution used in the semiconductor formation process.

Description

[Technical field]

[0001] The present invention relates to a ruthenium-containing gas (RuO) that is generated when a semiconductor wafer containing ruthenium is brought into contact with a processing liquid during the manufacturing process of a semiconductor device. 4 A new RuO for suppressing gases 4 Gas generation inhibitor and RuO 4 The present invention relates to a method for suppressing gas generation. [Background technology]

[0002] In recent years, the design rules for semiconductor elements have become finer, and the wiring resistance tends to increase. As a result of the increase in wiring resistance, it has become evident that the high-speed operation of semiconductor elements is hindered, and measures are required. Therefore, wiring materials with higher electromigration resistance and lower resistance than conventional wiring materials are desired.

[0003] Compared to the conventional wiring materials of aluminum and copper, ruthenium has high electromigration resistance and can reduce the resistance of wiring, so it has been attracting attention as a wiring material, especially for semiconductor device design rules of 10 nm or less.In addition to being used as a wiring material, ruthenium can prevent electromigration even when copper is used as the wiring material, so the use of ruthenium as a barrier metal for copper wiring is also being considered.

[0004] Incidentally, in the wiring formation process of semiconductor devices, even when ruthenium is selected as a wiring material, wiring is formed by dry or wet etching, as in the case of conventional wiring materials. However, since ruthenium is difficult to remove by dry etching using an etching gas or by etching using CMP polishing, more precise etching is desired, and specifically, wet etching has attracted attention.

[0005] When ruthenium is wet etched under alkaline conditions, it becomes, for example, RuO 4- Or RuO 4 2- It dissolves in the treatment solution as RuO 4 - Or RuO 4 2- In the treatment solution, RuO 4 A part of it is gasified and released into the gas phase. 4 is a strong oxidizing agent that is harmful to the human body and is easily reduced to RuO 2 Generally, particles are a major problem in the semiconductor manufacturing process because they reduce the yield. 4 It is very important to suppress the generation of gas.

[0006] Patent Document 1 discloses an etching solution for a ruthenium film, the etching solution having a pH of 12 or more and an oxidation-reduction potential of 300 mV vs. SHE or more. Furthermore, a method of etching a ruthenium film using a solution of an oxyacid salt of a halogen, such as hypochlorite, chlorite, or bromate, is presented.

[0007] Furthermore, Patent Document 2 proposes a method of oxidizing, dissolving and removing ruthenium using an aqueous solution containing orthoperiodic acid and having a pH of 11 or higher.

[0008] Patent Document 3 describes the use of RuO in chemical mechanical polishing (CMP) of ruthenium. 4 A CMP slurry containing ruthenium-coordinated nitric oxide ligands (NO ligands) that do not outgas has been disclosed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2002-161381 A [Patent Document 2] International Publication No. 2016 / 068183 [Patent Document 3] Japanese Patent Application Publication No. 5-314019 Summary of the Invention [Problem to be solved by the invention]

[0010] However, according to the investigations of the present inventors, it has been found that the conventional etching solutions described in Prior Art Documents 1 to 3 have room for improvement in the following respects.

[0011] For example, the method of etching ruthenium described in Patent Document 1 aims to remove ruthenium residues adhering to the back surface or bevel of a semiconductor substrate, and it is possible to dissolve and remove ruthenium. However, in Patent Document 1, RuO 4 In fact, the method described in Patent Document 1 does not mention the suppression of gas. 4 Gas generation could not be suppressed.

[0012] In addition, Patent Document 2 discloses a ruthenium removal composition containing orthoperiodic acid, and indicates that it is possible to etch etching residues containing ruthenium. However, Patent Document 2 discloses RuO 4 There is no mention of suppressing the gas, and the RuO generated during the etching process 4 The gas could not be contained.

[0013] In addition, Patent Document 3 describes the use of a CMP slurry containing a ruthenium-coordinated nitric oxide ligand (NO ligand) in CMP, which reduces the amount of toxic RuO 4 However, the CMP slurry shown in Patent Document 3 is acidic, and under alkaline conditions where the dissolution mechanism of ruthenium is different, the RuO 4 In fact, when the ruthenium NO ligand described in Patent Document 3 was added to an alkaline ruthenium etching solution containing hypochlorous acid, RuO 4 Gas is generated and RuO 4 It was confirmed that there was no gas suppression effect.

[0014] Therefore, an object of the present invention is to provide a method for treating ruthenium-containing semiconductor wafers, which is generated when the semiconductor wafers are brought into contact with a treatment liquid under alkaline conditions, and to provide a method for treating ruthenium-containing semiconductor wafers, which is generated when the treatment liquid is brought into contact with the treatment liquid under alkaline conditions. 4 RuO capable of suppressing gas 4 The object of the present invention is to provide a gas generation inhibitor. [Means for solving the problem]

[0015] The present inventors have conducted extensive research to solve the above problems. They have investigated the addition of various onium salts to a ruthenium-containing semiconductor wafer treatment solution. 4 Since it is not possible to suppress the gas, various additives were combined. As a result, by adding a specific onium salt, RuO 4 The inventors have found that it is possible to suppress the generation of gas, and have thus completed the present invention.

[0016] That is, the present invention is configured as follows. Item 1: RuO, including onium salts consisting of an onium ion and a bromine-containing ion 4 Gas generation inhibitor. Item 2. The RuO compound according to Item 1, wherein the onium salt is a quaternary onium salt represented by formula (1), a tertiary onium salt represented by formula (2), an onium salt represented by formula (3), or an onium salt represented by formula (4). 4 Gas generation inhibitor.

[0017] [ka]

[0018] [ka]

[0019] [ka]

[0020] [ka] (In formula (1), A + is an ammonium ion or a phosphonium ion, 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 When R is an alkyl group, 1 , R 2 , R 3 , R 4 At least one of the alkyl groups has a carbon number of 2 or more. 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 a fluorine atom, a chlorine atom, 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 a fluorine atom or a chlorine atom. In formula (2), A + is a sulfonium ion, and 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 When R is an alkyl group, 1 , R 2 , R 3At least one of the alkyl groups has a carbon number of 2 or more. 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 a fluorine atom, a chlorine atom, 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 a fluorine atom or a chlorine atom. In formula (3), Z is an aromatic group or alicyclic group which may contain a nitrogen atom, a sulfur atom or an oxygen atom, and in the aromatic group or alicyclic group, a hydrogen atom bonded to a carbon atom or a nitrogen atom may have a chlorine atom, a bromine atom, a fluorine atom, an iodine atom, at least one alkyl group having 1 to 15 carbon atoms, at least one alkenyloxy group having 2 to 9 carbon atoms, an aromatic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms. + is an ammonium ion or a sulfonium ion. R is a chlorine atom, a bromine atom, a fluorine atom, an iodine atom, an alkyl group having 1 to 15 carbon atoms, an allyl group, an aromatic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. In formula (4), A + are independently an ammonium ion or a phosphonium ion, and R 1 , R 2 , R 3 , R 4 , R 5 , R 6are 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. In the aryl group in the aralkyl group and in the ring of the aryl group, at least one hydrogen atom may be replaced by a fluorine atom, a chlorine atom, 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 a fluorine atom or a chlorine atom. a is an integer of 1 to 10. In formulas (1) to (4), X - is a bromine-containing ion.) Item 3: The quaternary onium salt is a tetraethylammonium ion, a tetrapropylammonium ion, Item 3. The RuO salt according to item 2, which is a salt of at least one ammonium ion selected from the group consisting of ammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, and tetrahexylammonium ion. 4 Gas generation inhibitor. Item 4 The onium salt RuO 4 The RuO according to any one of items 1 to 3, wherein the concentration in the gas generation inhibitor is 0.0001 to 50 mass%. 4 Gas generation inhibitor. Item 5. The RuO according to any one of Items 1 to 4, 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. Item 6 The RuO 4 6. The RuO according to any one of items 1 to 5, wherein the hypobromite ion concentration in the gas generation inhibitor is 0.001 mol / L or more and 0.20 mol / L or less. 4 Gas generation inhibitor. Item 7 The RuO 4 Item 7. The RuO according to any one of items 1 to 6, wherein the hypobromite ion concentration in the gas generation inhibitor is 0.01 mol / L or more and 0.10 mol / L or less. 4 Gas generation inhibitor. Item 8 The RuO 4The gas generation inhibitor has a pH of 8 to 14 at 25° C. 4 Gas generation inhibitor. Item 9 The RuO 4 The gas generation inhibitor has a pH of 12 to 13 at 25° C. 4 Gas generation inhibitor. Item 10 The RuO 4 The gas generation inhibitor according to any one of items 1 to 9, further comprising an oxidizing agent different from the bromine-containing ion. 4 Gas generation inhibitor. Item 11. The RuO according to Item 10, wherein the oxidizing agent is an oxidizing agent containing hypochlorite ions or ozone. 4 Gas generation inhibitor. Item 12. The RuO according to any one of items 1 to 11. 4 A process using a gas generation inhibitor, RuO 4 A method to suppress gas generation. Effect of the Invention

[0021] The RuO 4 The gas generation inhibitor, RuO, which causes particles and reduces yields in the semiconductor manufacturing process, is effectively suppressed by the effect of onium salts. 4 Gas generation can be suppressed. In addition, the selectable pH range and the number of oxidizing agents increases, making it possible to realize a stable processing solution by selecting an appropriate oxidizing agent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (RuO 4 Gas generation inhibitor) RuO 4 The gas generation inhibitor is added to the solution for treating ruthenium (hereinafter referred to as the ruthenium treatment solution) to suppress the generation of RuO 4 A composition that suppresses gas generation, it refers to a liquid containing an onium salt consisting of an onium ion and a bromine-containing ion.

[0023] The ruthenium treatment liquid refers to a liquid containing a component that contacts ruthenium and causes a physical or chemical change to the ruthenium. For example, it can be a liquid used in a process for treating ruthenium, such as an etching process, a residue removal process, a cleaning process, or a CMP process in a semiconductor manufacturing process. It also includes a liquid for cleaning ruthenium attached to the inner walls of a chamber, piping, etc., in each device used in these semiconductor manufacturing processes.

[0024] The ruthenium treated with the ruthenium treatment solution is dissolved, dispersed or precipitated in whole or in part in the ruthenium treatment solution, and becomes RuO 4 (gas) and / or RuO 2 The RuO of the present invention is added to the ruthenium treatment solution. 4 By adding a gas generation inhibitor, RuO 4 - Or RuO 4 2- Anions such as RuO 4 - etc.) and onium ions form ion pairs that dissolve in the ruthenium treatment solution, forming RuO 4 Gas and / or RuO 2 The occurrence of the above can be suppressed.

[0025] (onium salts) The RuO 4 Gas generation inhibitors include RuO 4 In order to suppress the generation of gas, an onium salt is included. The onium salt is composed of an onium ion and a bromine-containing ion. Here, the bromine-containing ion is an ion containing bromine, and examples thereof include bromite ion, bromate ion, perbromate ion, hypobromite ion, and bromide ion. The RuO 4 The onium salt contained in the gas generation inhibitor is RuO 4 In order to exert the gas suppression ability, the onium salt must dissociate into an onium ion and a bromine-containing ion. The onium ion generated by the dissociation of the onium salt is RuO 4- etc., and RuO 4 This is to suppress the generation of gas. Onium salts containing halogen-containing ions are easily dissociated, have excellent solubility, and can stably supply onium ions. 4 It can be used as the onium salt contained in the gas generation inhibitor. 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, so that high-purity products are available industrially at low cost. In addition, onium salts containing bromine-containing ions have the advantage of having more onium ions per unit weight than those containing iodine-containing ions. Therefore, RuO 4 The onium salt contained in the gas generation inhibitor contains a bromine-containing ion.

[0026] By including the above onium salt, RuO from the ruthenium treatment solution is prevented. 4 Gas generation is suppressed. That is, RuO generated by dissolving ruthenium 4 - etc. are trapped in the ruthenium treatment solution due to electrostatic interaction with the onium ions. Trapped RuO 4 - Since these exist relatively stably as ion pairs in the treatment solution, RuO 4 This means that RuO 4 Gas generation is suppressed and RuO 2 The generation of particles is also suppressed.

[0027] RuO 4 As the onium salt having the effect of suppressing gas emission, those represented by the following formulae (1) to (4) are preferred.

[0028] [ka] (In formula (1), A + is an ammonium ion or a phosphonium ion, and R 1 , R 2 , R 3 , R 4are 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 When R is an alkyl group, 1 , R 2 , R 3 , R 4 At least one of the alkyl groups has 2 or more carbon atoms. At least one hydrogen atom in the aryl group and in the ring of the aryl group in the aralkyl group is replaced by a fluorine atom, a chlorine atom, an alkyl group having 1 to 10 carbon atoms, It may be replaced by 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 may be replaced by a fluorine atom or a chlorine atom. - is a bromine-containing ion.)

[0029] [ka] (In formula (2), A + is a sulfonium ion, and 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 When R is an alkyl group, 1 , R 2 , R 3 At least one of the alkyl groups has 2 or more carbon atoms. In addition, at least one hydrogen atom in the aryl group and in the ring of the aryl group in the aralkyl group may be replaced with a fluorine atom, a chlorine atom, 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 a fluorine atom or a chlorine atom. X - is a bromine-containing ion.)

[0030] R in the above formula (1) or (2) 1 , R 2 , R 3 , R 4 The alkyl groups may be independently selected from 1 to 25, without any particular limitation. The larger the carbon number, specifically, the greater the carbon number, for example, 3 or more, the more easily the onium ion becomes RuO 4 - etc., so RuO 4 On the other hand, the larger the carbon number, the bulkier the onium ion becomes, so RuO 4 - When electrostatic interactions occur with the ruthenium salts, the ion pairs that are generated become less soluble in the ruthenium treatment solution, resulting in the formation of precipitates. These precipitates become particles and cause a decrease in the yield of semiconductor devices. In addition, the larger the carbon number, the lower the solubility in the ruthenium treatment solution, and the more likely it is that bubbles will form in the treatment solution. High solubility allows more onium salts to be dissolved in the treatment solution, so RuO 4 On the other hand, if the carbon number is small, the onium ion and RuO 4 - The interaction with RuO etc. is weaker. 4 Therefore, the number of carbon atoms of the alkyl group in the formula (1) or (2) is preferably 1 to 25, more preferably 2 to 10, and most preferably 3 to 6. However, when R in the formula (1) 1 , R 2 , R 3 , R 4 When R is an alkyl group, 1 , R 2 , R 3 , R 4 At least one of the alkyl groups may have 2 or more carbon atoms, and R in formula (2) 1 , R 2 , R 3 When R is an alkyl group, 1 , R 2 , R 3At least one of the alkyl groups may have 2 or more carbon atoms. In the case of an onium salt having an alkyl group with such a carbon number, RuO 4 - RuO 4 RuO 4 It can be suitably used as a gas generation inhibitor.

[0031] R in the above formula (1) or (2) 1 , R 2 , R 3 , R 4 The 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, etc. , chlorine, bromine, and iodine.

[0032] The quaternary and tertiary onium salts represented by the above formulas (1) and (2) are RuO 4 These are salts consisting of ammonium ions, phosphonium ions and sulfonium ions that can stably exist in the gas generation inhibitor or ruthenium treatment solution. In general, the alkyl chain length of these ions can be easily controlled, and further, it is easy to introduce allyl groups or aryl groups. This makes it possible to control the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surface activity, etc. of the ions, and the salts consisting of the ions can also be controlled in the same way. Such salts can be used as the onium salts represented by formulas (1) and (2) of the present invention.

[0033] [ka] (In formula (3), Z is an aromatic group or alicyclic group which may contain a nitrogen atom, a sulfur atom or an oxygen atom, and in the aromatic group or alicyclic group, a hydrogen atom bonded to a carbon atom or a nitrogen atom may have a chlorine atom, a bromine atom, a fluorine atom, an iodine atom, at least one alkyl group having 1 to 15 carbon atoms, at least one alkenyloxy group having 2 to 9 carbon atoms, an aromatic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms. A + is an ammonium ion or a sulfonium ion. R is a chlorine atom, a bromine atom, a fluorine atom, an iodine atom, an alkyl group having 1 to 15 carbon atoms, an allyl group, an aromatic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. X - is a bromine-containing ion.)

[0034] Onium salts with the above structure are alkaline RuO 4 In addition, in the above formula (3), by making the hydrogen atom bonded to the carbon atom or nitrogen atom of the aromatic group or alicyclic group of Z an aromatic group substituted with an alkyl group, an aromatic group substituted with an alkenyloxy group, or an alicyclic group substituted with an alkyl group, having a suitable number of carbon atoms, or by appropriately selecting the alkyl group, allyl group, aromatic group which may be substituted with an alkyl group, or alicyclic group which may be substituted with an alkyl group of R, the RuO 4 Solubility in gas generation inhibitors or ruthenium treatment solutions, and onium ions and RuO 4 - It is possible to control the stability of ion pairs with the above.

[0035] Examples of such onium ions include cations such as 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. ions, and oxazolium ions are preferred.

[0036] Specific examples of onium salts consisting of these onium ions include 1-butyl-2,3-dimethylimidazolium bromide, 1-hexyl-3-methylimidazolium bromide, 1-methyl-3-n-octylimidazolium bromide, 1-butyl-1-methylpyrrolidinium bromide, 1-ethyl-1-methylpyrrolidinium bromide, 1-butyl-1-methylpiperidinium bromide, 5-azoniaspiro[4,4]nonane bromide, 1-methylpyridinium bromide, 1-ethylpyridinium bromide, 1-propylpyridinium bromide, and the like.

[0037] [ka] (In formula (4), A + are independently an ammonium ion or a phosphonium ion, and R 1 , R 2 , R 3 , R 4 , R 5 , R 6are 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. In the aryl group in the aralkyl group and in the ring of the aryl group, at least one hydrogen atom may be replaced by a fluorine atom, a chlorine atom, 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 a fluorine atom or a chlorine atom. a is an integer of 1 to 10. X - is a bromine-containing ion.)

[0038] R in the above formula (4) 1 , R 2 , R 3 , R 4 , R 5 , R 6 The alkyl groups may be independently selected from 1 to 25 without any particular limitation. The onium salt shown in the above formula (1) has a valence of 1, but the onium salt shown in the formula (4) is a dication with a valence of 2, so that RuO 4 - Therefore, even if the number of carbon atoms in the alkyl group in formula (4) is smaller than that in formula (1), RuO 4 For the above reasons, the number of carbon atoms in the alkyl group in formula (4) is preferably 1 to 25, more preferably 1 to 10, and most preferably 1 to 6. In the case of an onium salt having an alkyl group with such a carbon number, RuO 4 - RuO 4 RuO 4 It can be suitably used as a gas generation inhibitor.

[0039] R in the above formula (4) 1 , R 2 , R 3 , R 4 , R 5 , R 6The 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 the heteroatom include nitrogen, oxygen, sulfur, phosphorus, chlorine, bromine, and iodine.

[0040] The onium salt represented by the above formula (4) is RuO 4 The gas generation inhibitor or ruthenium treatment solution is made of ammonium ions or phosphonium ions that can exist stably. In general, the alkyl chain length of the ammonium ions or phosphonium ions can be easily controlled, and it is also easy to introduce allyl groups or aryl groups. This allows the ammonium ions It is also possible to control the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surface activity, etc. of the phosphonium ion.

[0041] As the onium salt represented by the above formula (4), hexamethonium bromide and decamethonium bromide can be mentioned. 4 Gas generation inhibitors are particularly useful in the treatment of ruthenium, such as RuO 4 Gas and RuO 2 The generation of particles can be suppressed.

[0042] The RuO 4 The quaternary onium salt represented by formula (1) contained in the gas generation inhibitor is preferably an ammonium salt, because it is highly stable, highly pure products are easily available industrially, and inexpensive. Among them, the onium salt is preferably a tetraalkylammonium salt, because it is particularly stable and can be easily synthesized. Specific examples include salts made of tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, or tetrahexylammonium ion. Inhibitors containing such onium salts are particularly useful in treating ruthenium, particularly RuO 4 Gas and RuO 2It is possible to suppress the generation of particles.

[0043] In addition, the RuO 4 The concentration of the onium salt in the gas generation inhibitor is preferably 0.0001 to 50 mass %. If the concentration of the onium salt is too low, RuO 4 - The interaction with RuO 4 Not only does it reduce the gas suppression effect, but it also dissolves in the ruthenium treatment solution. 4 - The amount of RuO etc. is reduced, so that the number of times the ruthenium treatment solution can be reused is reduced. On the other hand, if the amount added is too large, the amount of onium ions adsorbed to the ruthenium surface increases, causing a decrease in the ruthenium dissolution rate and non-uniform etching of the ruthenium surface. Therefore, the RuO 4 The gas generation inhibitor preferably contains an onium salt in an amount of 0.0001 to 50% by mass, more preferably in an amount of 0.01 to 35% by mass, and even more preferably in an amount of 0.1 to 20% by mass. 4 The gas generation inhibitor and the ruthenium treatment solution may also be mixed together to have the above concentration range. 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 included, as long as the total concentration of the onium salts is within the above concentration range, RuO 4 Gas generation can be effectively suppressed. Moreover, the above-mentioned onium salt concentration range is applicable to any of the onium salts represented by the formulas (1) to (4).

[0044] (Oxidizing agent) The RuO 4The gas generation inhibitor can contain an oxidizing agent. The oxidizing agent refers to an agent capable of substantially dissolving ruthenium contained in a semiconductor wafer. Any oxidizing agent known to be capable of dissolving ruthenium can be used as the oxidizing agent without any restrictions. Examples of the oxidizing agent include, but are not limited to, halogen oxygen acid, permanganic acid and their salts, hydrogen peroxide, ozone, and cerium (IV) salts. Here, the halogen oxygen acid refers to hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, metaperiodic acid, orthoperiodic acid, or ions thereof. The oxidizing agent can dissolve ruthenium contained in the wafer, so that RuO containing the oxidizing agent and an onium salt is preferably used. 4 Gas generation is suppressed by dissolving ruthenium and RuO 4 Gas suppression can be achieved at the same time. In addition, the inclusion of an oxidizing agent promotes the dissolution of ruthenium and also reduces the amount of precipitated RuO 2 This promotes the re-dissolution of particles. For this reason, RuO 4 Gas generation is suppressed by RuO 4 Gas and RuO 2 It is possible to efficiently process ruthenium-containing wafers while suppressing generation of particles.

[0045] Among the oxidizing agents, halogen oxygen acid, ions of halogen oxygen acid, hydrogen peroxide, or ozone are suitable as the oxidizing agent because they can be used stably in an alkaline state and can be selected from a wide range of concentrations. Hypochlorous acid, hypobromous acid, metaperiodic acid, orthoperiodic acid, their ions, or ozone are more suitable. Hypochlorous acid, hypobromous acid, hypochlorite ions, hypobromite ions, or ozone are even more suitable. Hypobromite ions, hypochlorite ions, or ozone are even more suitable. Hypobromite ions or hypochlorite ions are the most suitable. These oxidizing agents may be present in the treatment liquid as salts. Examples of the salts include tetraalkylammonium hypochlorite or tetraalkylammonium hypobromite, and tetramethylammonium hypochlorite or tetramethylammonium hypobromite are more suitable. The oxidizing agent contained in the treatment liquid may be one type or two or more types. For example, RuO 4 When the gas generation inhibitor contains a bromine-containing ion as an oxidizing agent, the RuO 4 The gas generation inhibitor may further contain an oxidizing agent different from the bromine-containing ion. Such an oxidizing agent different from the bromine-containing ion is preferably an oxidizing agent containing hypochlorite ion or ozone, and more preferably an oxidizing agent containing hypochlorite ion. The reason will be explained below by taking the case where the bromine-containing ion is hypobromite ion as an example. Hypobromite ion is formed by oxidation of ruthenium, etc., natural decomposition, decomposition by ultraviolet light, thermal decomposition, contact with a reducing agent or acid, etc., to Br - It is reduced to Br - does not dissolve ruthenium, RuO 4 Low gas suppression effect, RuO 2 Since the particles are not redissolved, the reduction of hypobromite ions results in RuO 4 The RuO of the present invention tends to decrease its suppression ability. 4 By including an appropriate oxidizing agent other than hypobromite ion, such as hypochlorite ion or ozone, in the gas generation inhibitor, the Br generated by reduction or decomposition can be reduced. - can be reoxidized to hypobromite ion, and the reduction of hypobromite ion causes RuO4 It is possible to slow down the decline in the ability to suppress gas generation. In other words, by including hypobromite ions and an appropriate oxidizing agent in the treatment liquid, RuO 4 The stability of the gas generation inhibitor is improved. As for such an oxidizing agent, the oxidation-reduction potential between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent is hypobromite ion / Br - It is sufficient to exceed the redox potential of the system, but in particular, Br - Since hypochlorite ion or ozone can be oxidized to hypobromite ion, hypochlorite ion or ozone is preferred.

[0046] The method for producing the above-mentioned tetramethylammonium hypochlorite or tetramethylammonium hypobromite is not particularly limited, and those produced by widely known methods can be used.For example, tetramethylammonium hypochlorite or tetramethylammonium hypobromite produced by a method of blowing chlorine or bromine into tetramethylammonium hydroxide, a method of mixing hypochlorous acid or hypobromous acid with tetramethylammonium hydroxide, a method of replacing cations in a hypochlorite or hypobromite solution with tetramethyl ions using an ion exchange resin, or a method of mixing a distillate of a solution containing hypochlorite or hypobromous acid with tetramethylammonium hydroxide can be suitably used.

[0047] The RuO 4 The concentration of the hypobromite ions contained in the gas generation inhibitor is not particularly limited as long as it does not deviate from the object of the present invention, but the amount of bromine contained in the hypobromite ions is preferably 0.001 mol / L or more and 0.20 mol / L or less, more preferably 0.005 mol / L or more and 0.20 mol / L or less, and most preferably 0.01 mol / L or more and 0.10 mol / L or less. If the hypobromite ion concentration is too low, the amount of RuO generated by the dissolution of ruthenium increases. 2 Since the particles cannot be dissolved, RuO 2If the hypobromite ion concentration is too high, the onium ion is oxidized, promoting decomposition, which may reduce the gas suppression effect. 4 The gas generation inhibitor is RuO 4 Gas and RuO 2 It is possible to efficiently process ruthenium-containing wafers while suppressing generation of particles.

[0048] (pH) The RuO 4 The gas generation inhibitor preferably has a pH of 8 to 14 at 25° C. If the pH is less than 8, the dissolution of ruthenium is limited to RuO 4 - RuO instead of anions such as 2 Or Ru(OH) 3 This tends to occur via the RuO 2 is a particle source, and at pH levels below 8, RuO 4 Problems such as increased gas generation also occur. In addition, when the pH is higher than 14, RuO 2 Since redissolution of RuO 2 The generation of particles is a problem. 4 In order to fully exert the gas generation suppression ability, the pH of the suppressor is preferably 8 to 14, more preferably 12 to 13. In this pH range, the dissolved ruthenium becomes RuO 4 - or RuO 4 2- Since it exists as an anion of RuO, it easily forms an ion pair with the onium ion contained in the inhibitor, effectively 4 Gas generation can be suppressed.

[0049] (Other Ingredients) The RuO 4The gas generation inhibitor may contain other additives that have been used in semiconductor processing solutions, if desired, within the scope of the invention. For example, other additives may include acids, metal anticorrosives, water-soluble organic solvents, fluorine compounds, oxidizing agents, reducing agents, complexing agents, chelating agents, surfactants, defoamers, pH adjusters, stabilizers, etc. These additives may be added alone or in combination.

[0050] These additives also lead to the formation of RuO 4 Due to the convenience of manufacturing the gas generation inhibitor, the RuO 4 The gas generation inhibitor may contain alkali metal ions, alkaline earth metal ions, etc. For example, sodium ions, potassium ions, calcium ions, etc. However, since these alkali metal ions and alkaline earth metal ions, etc., have a negative effect on the semiconductor element (such as a negative effect on the yield of the semiconductor wafer) if they remain on the semiconductor wafer, it is preferable that the amount of these ions is small, and in fact, it is better that they are not contained as much as possible. Therefore, for example, as a pH adjuster, it is preferable that the pH adjuster is 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.

[0051] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1 mass% or less, more preferably 0.7 mass% or less, even more preferably 0.3 mass% or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0052] The RuO 4In the gas generation inhibitor, the remainder other than the onium salt and other additives is water. The water contained in the inhibitor is preferably water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and is particularly preferably pure water or ultrapure water. Such water can be obtained by a known method that is widely used in semiconductor manufacturing.

[0053] (RuO 4 (Method of suppressing gas generation) RuO 4 The gas generation suppression method of the present invention is 4 The method includes a step of adding a gas generation inhibitor to a ruthenium processing solution. Specifically, for example, the method includes adding the RuO 4 By adding a gas generation inhibitor, RuO 4 In addition, when cleaning ruthenium adhering to the inner walls of the chambers and piping in the various devices used in the semiconductor manufacturing process, the RuO 4 By using a gas generation inhibitor, RuO 4 It is possible to suppress the generation of gas. For example, physical vapor deposition (PVD) and chemical In the maintenance of equipment that forms Ru using chemical vapor deposition (CVD) or atomic layer deposition (ALD), the cleaning solution used to remove Ru that has adhered to the chamber, piping, etc. is used to remove the RuO 4 By adding a gas generation inhibitor, RuO generated during cleaning is reduced. 4 According to this method, the gas can be suppressed by the above-mentioned mechanism. 4 Gas generation can be suppressed.

[0054] For example, in the process of forming ruthenium wiring, the RuO 4When a gas generation inhibitor is used, the 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. 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 further formed. This ruthenium film is then oxidized by the RuO 4 By etching with a ruthenium treatment solution containing a gas generation inhibitor, RuO 4 Planarization is performed while suppressing gas generation. This allows the RuO 2 It is possible to form highly reliable ruthenium wiring with reduced particle generation. 4 The ruthenium treatment solution to which the gas generation inhibitor has been added can also be used when removing ruthenium adhering to the bevel of a semiconductor wafer.

[0055] The RuO 4 The gas generation inhibitor is RuO not only for the ruthenium treatment solution but also for the solution after ruthenium treatment (hereinafter referred to as ruthenium-containing solution). 4 The generation of gas can be suppressed. Here, the ruthenium-containing liquid means a liquid that contains ruthenium even in a small amount. The ruthenium contained in the ruthenium-containing liquid is not limited to ruthenium metal, and may be any liquid that contains ruthenium element, such as Ru, RuO 4 - , RuO 4 2- , RuO 4 , RuO 2、 Examples of the ruthenium-containing liquid include the waste liquid generated in the semiconductor manufacturing process and chamber cleaning, and RuO 4 Examples include the treatment liquid in exhaust gas treatment equipment (scrubber) that captures gas. If even a small amount of ruthenium is present in the ruthenium-containing liquid, it will become RuO 4 RuO via gas 2The particles generated contaminate tanks and piping, and the oxidation of the particles accelerates the deterioration of equipment. 4 The gas is highly toxic to the human body even at low concentrations. Thus, ruthenium-containing liquids have various adverse effects on equipment and the human body. 4 It is necessary to treat the ruthenium-containing liquid safely and quickly while suppressing the generation of gas. 4 By adding a gas generation inhibitor, RuO 4 This not only suppresses gas generation, allowing the ruthenium-containing liquid to be treated safely, but also reduces contamination and deterioration of the tanks and piping of the equipment.

[0056] The RuO 4 When the gas generation inhibitor is mixed with a ruthenium treatment solution or a ruthenium-containing solution, the RuO 4 The concentration of the onium salt contained in the gas generation inhibitor is preferably adjusted so that the concentration of one or more onium salts in the mixed liquid is 0.0001 to 50 mass %.

[0057] The RuO of the present invention for a ruthenium processing solution or a ruthenium-containing solution 4 The amount of gas generation inhibitor to be added may be determined taking into consideration the amount of ruthenium present in these solutions. 4 The amount of the gas generation inhibitor added is not particularly limited, but for example, when the amount of ruthenium present in the ruthenium treatment liquid or the ruthenium-containing liquid is taken as 1, the weight ratio is preferably 10 to 500,000, more preferably 100 to 100,000, and even more preferably 1,000 to 50,000. In addition, RuO 4 The pH of the mixture of the gas generation inhibitor and the ruthenium treatment liquid or the ruthenium-containing liquid at 25° C. is preferably, for example, 7 to 14. In order to adjust the pH of this mixture, the pH adjusters exemplified above may be added. EXAMPLES

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] <Examples 1 to 22 and Comparative Examples 1 to 4> (Ruthenium treatment solution and RuO 4 Preparation of gas generation inhibitor mixture First, 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 pH shown in Table 1 using a 15 mass% HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution to obtain 30 mL of ruthenium treatment solution. Next, an onium salt and ultrapure water were added to a 100 mL fluororesin container, and the pH was adjusted to the pH shown in Table 1 in the same manner as above to obtain 30 mL of RuO 4 A gas generation inhibitor was obtained. The onium salt of Example 21 was prepared by mixing sodium bromate and an aqueous solution of tetrapropylammonium hydroxide. The obtained ruthenium treatment solution and RuO 4 A gas generation inhibitor was mixed to obtain 60 mL of a mixed liquid. 4 Instead of the gas inhibitor, 30 mL of ultrapure water adjusted to the same pH as the ruthenium treatment solution was mixed in. It was confirmed that the oxidant concentration of the ruthenium treatment solution to which sodium hypochlorite was added was 0.56 mol / L (effective chlorine concentration of 4.0 mass%).

[0060] (pH measurement method) The pH of 10 mL of the mixed solution prepared in each Example and Comparative Example was measured using a tabletop pH meter (LAQUAF-73, manufactured by Horiba, Ltd.) The pH measurement was performed after the mixed solution was prepared and stabilized at 25°C.

[0061] (RuO 4 Quantitative evaluation of gases) RuO 4The amount of gas generated was measured using ICP-OES. 5 mL of the mixed solution was placed in a sealed container, and a 10 x 20 mm Si wafer with a ruthenium film of 1200 Å thickness was immersed in it at 25°C or 50°C until all of the ruthenium was dissolved. The temperature of the mixed solution during immersion (treatment temperature) is shown in Table 1 or Table 2. Air was then flowed into the sealed container, and the gas phase in the sealed container was bubbled into a container containing an absorbing liquid (1 mol / L NaOH) to measure the RuO generated during the wafer immersion. 4 The gas was trapped in the absorbing solution. The amount of ruthenium in the absorbing solution was measured by ICP-OES, and the amount of RuO 4 The amount of Ru in the gas was calculated. 4 The amount of Ru in the gas is the weight of ruthenium contained in the absorption solution divided by the area of ​​the immersed wafer. The complete dissolution of the ruthenium on the Si wafer immersed in the mixed solution was confirmed by measuring the sheet resistance before and after immersion with a four-point resistance probe (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converting it into film thickness.

[0062] <Example 23 and Comparative Example 5> As an oxidizing agent, 0.07 mol / L orthoperiodic acid (H 5 IO 6 A mixed solution was prepared in the same manner as in Example 1 or Comparative Example 1, except that a RuO 4 A quantitative evaluation of the gas was performed.

[0063] <Examples 24 to 28> A mixed solution was prepared in the same manner as in Example 4, except that sodium hypobromite (NaBrO; manufactured by Kanto Chemical) was used at concentrations of 0.002, 0.02, 0.2, 0.4, and 0.6 mol / L as the oxidizing agent. The concentration of sodium hypobromite in the mixed solution was confirmed using an ultraviolet-visible spectrophotometer (UV-2600, manufactured by Shimadzu Corporation). Using this mixed solution, pH was measured in the same manner as in Example 1, and RuO 4 A quantitative evaluation of the gas was performed.

[0064] <Example 29> RuO further containing 0.56 mol / L sodium hypochlorite 4 Gas generation inhibitor A mixed solution was prepared in the same manner as in Example 4, except that RuO was used. 4 A quantitative evaluation of the gas was performed.

[0065] <Examples 30 to 51> (Ruthenium-containing liquid and RuO 4 Preparation of gas generation inhibitor mixture Sodium hypochlorite (manufactured by Wako Pure Chemical Industries, Ltd.) and ultrapure water were added to a 100 mL fluororesin container to obtain 30 mL of ruthenium treatment solution. The pH of the ruthenium treatment solution was adjusted to the same value as the pH of the ruthenium-containing solution listed in Table 2 using a 15 mass% HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution. Six 10×20 mm Si wafers with a ruthenium film of 2400 Å thickness were immersed in 30 mL of the obtained treatment solution at 25° C. until all the ruthenium was dissolved, thereby obtaining the ruthenium-containing solution listed in Table 2. The concentration of ruthenium contained in the ruthenium-containing solution measured by ICP-OES is shown in Table 2. Next, an onium salt and ultrapure water were added to a 100 mL fluororesin container, and the pH was adjusted to the value shown in Table 2 to obtain 30 mL of RuO 4 A gas generation inhibitor was obtained. The onium salt of Example 50 was prepared by mixing sodium bromate and an aqueous solution of tetrapropylammonium hydroxide. The obtained ruthenium-containing liquid and RuO 4 The pH of the liquid containing the gas generation inhibitor (mixed liquid) was measured by the method described in Example 1, and the RuO 4 The gas was quantitatively evaluated. The temperature of the mixture during wafer immersion (processing temperature) is shown in Table 2. However, since the mixture already contains ruthenium, RuO 4 In the quantitative evaluation of the gases, no dissolution of ruthenium was performed.

[0066] <Example 52> A mixed solution was prepared in the same manner as in Example 30, except that 0.035 mol / L orthoperiodic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the oxidizing agent. 4 A quantitative evaluation of the gas was performed.

[0067] <Examples 53 to 57> A mixed solution was prepared in the same manner as in Example 33, except that sodium hypobromite was used at concentrations of 0.001, 0.01, 0.1, 0.2, and 0.3 mol / L as the oxidizing agent. The concentration of sodium hypobromite in the mixed solution was confirmed using an ultraviolet-visible spectrophotometer (UV-2600, manufactured by Shimadzu Corporation). Using this mixed solution, RuO 4 A quantitative evaluation of the gas was performed.

[0068] <Example 58> 0.42 g of tetrapropylammonium ruthenium peroxide and ultrapure water were added to a 1.5 L fluororesin container, and the pH was adjusted to the value shown in Table 2 using a 15 mass % HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution to obtain 1 L of a ruthenium-containing solution. Next, an onium salt and ultrapure water were added to a 100 mL fluororesin container, and the pH was adjusted to the value shown in Table 2 to obtain 30 mL of RuO 4 A gas generation inhibitor was obtained. The resulting ruthenium-containing solution (30 mL) and RuO 4 The liquid mixed with 30 mL of the gas generation inhibitor was subjected to RuO 4 A quantitative evaluation of the gas was performed.

[0069] <Example 59> 4.8 mg RuO 2 The powder was dispersed in 30 mL of ultrapure water to prepare a ruthenium-containing solution. The ruthenium-containing solution was adjusted to pH 12.0 using a 15 mass% HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution. Next, the onium salt and ultrapure water shown in Table 2 were added to a 100 mL fluororesin container, and the pH was adjusted to the pH shown in Table 2 to obtain 30 mL of RuO 4A gas generation inhibitor was obtained. The obtained ruthenium-containing liquid and RuO 4 The mixture obtained by mixing the gas generation inhibitor was used to prepare RuO 4 Quantitative evaluation of gas went.

[0070] <Example 60> 1.9 mg Ru powder and 2.4 mg RuO 2 The powder was added to ultrapure water and adjusted to the pH shown in Table 2 using a 15% by mass HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution. -4 mol / L of Ru and 6.0×10 -4 mol / L of RuO 2 Thus, 30 mL of a ruthenium-containing solution was obtained. Next, an onium salt and ultrapure water were added to a 100 mL fluororesin container, and the pH was adjusted to the value shown in Table 2 to obtain 30 mL of RuO 4 A gas generation inhibitor was obtained. The resulting ruthenium-containing solution (30 mL) and RuO 4 The gas generation inhibitor (30 mL) was mixed at 25°C (mixture) and the RuO 4 A quantitative evaluation of the gas was performed.

[0071] <Example 61> Sodium hypochlorite (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 value shown in Table 2 using a 15% by mass HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution. 1.9 mg of Ru powder and 2.4 mg of RuO were added to the obtained ruthenium treatment solution. 2 By adding powder, 6.0×10 -4 mol / L of Ru and 6.0×10 -4 mol / L of RuO 2 Thus, 30 mL of a ruthenium-containing solution was obtained. Next, an onium salt and ultrapure water were added to a 100 mL fluororesin container, and the pH was adjusted to the value shown in Table 2 to obtain 30 mL of RuO 4 A gas generation inhibitor was obtained. The resulting ruthenium-containing solution (30 mL) and RuO 4 The liquid mixed with 30 mL of the gas generation inhibitor was subjected to RuO 4 A quantitative evaluation of the gas was performed.

[0072] <Comparative Examples 6 to 10> Sodium hypochlorite (Wako Pure Chemical Industries, Ltd.) or orthoperiodic acid (FUJIFILM Wako Pure Chemical Industries, Ltd.) and ultrapure water were added to a 100 mL fluororesin container, and the pH was adjusted to the pH shown in Table 2 using a 15 mass% HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution to obtain 30 mL of ruthenium treatment solution. Six 10 x 20 mm Si wafers with a ruthenium film of 2400 Å thickness were immersed in 30 mL of the obtained ruthenium treatment solution at 25 ° C until all ruthenium was dissolved, to obtain the ruthenium-containing solution shown in Table 2. It was confirmed that the ruthenium-containing solution to which sodium hypochlorite was added had a pH of 0.28 mol / L (effective chlorine concentration of 2.0 mass%). The obtained ruthenium-containing solution was mixed with 30 mL of ultrapure water adjusted to the same pH, and RuO 4 A quantitative evaluation of the gas was performed.

[0073] [Table 1]

[0074] [Table 2]

[0075] Comparing Example 1 and Comparative Example 1 (pH 8.0), Example 4 and Comparative Example 2 (pH 12.0), and Example 5 and Comparative Example 3 (pH 12.5), the addition of an onium salt increased the RuO 4 It can be seen that the amount of gas generated can be suppressed. In Examples 1 to 3, the amount of onium salt added was changed, and the more the amount of onium salt added, the more the amount of RuO 4 It was confirmed that the gas suppression effect was high.

[0076] In Examples 8 to 21, different onium salts were used from those in Examples 1 to 7, as shown in the above formulas (1) to (4). In each case, however, RuO 4 The gas generation suppression effect was obtained. The concentration of the onium salt in Example 4 was 10 mass %, whereas in Example 9 it was 0.2 mass %. Thus, in Example 9, in which the onium salt has a larger carbon number, the same level of RuO was obtained with a smaller amount of addition. 4 The effect of suppressing gas generation has been achieved.

[0077] Comparing Comparative Example 4 and Example 22, even at 50°C, the addition of an onium salt resulted in the formation of RuO 4 It is clear that gas generation is suppressed.

[0078] Comparing Comparative Example 2 with Examples 24 to 28, even when 0.002 to 0.6 mol / L of NaBrO was used as an oxidizing agent, the addition of an onium salt resulted in the production of RuO 4 It is clear that gas generation is suppressed.

[0079] Comparing Comparative Example 5 and Example 23, even when 0.07 mol / L orthoperiodic acid was used as the oxidizing agent, the addition of an onium salt resulted in the production of RuO 4 It is clear that gas generation is suppressed.

[0080] From the results in Table 2, it is clear that RuO 4 It was found that when a gas generation inhibitor was added to a ruthenium-containing liquid, the generation of ruthenium-containing gas was suppressed. 4 It was shown that the gas generation inhibitor can be suitably used in the treatment of a ruthenium-containing liquid.

Claims

1. RuO ４ A ruthenium treatment solution containing a gas generation inhibitor, The onium salt is a quaternary onium salt represented by formula (1), a tertiary onium salt represented by formula (2), an onium salt represented by formula (3), or an onium salt represented by formula (4), RuO ４ A ruthenium treatment solution containing a gas generation inhibitor. 【Chemistry 1】 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】 (In formula (1), A ＋ is an ammonium ion or a phosphonium ion, R １ , R ２ , R ３ , R ４ are independently an alkyl group having 1 to 12 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 When R is an alkyl group, １ , R ２ , R ３ , R ４ At least one of the alkyl groups has 2 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 a fluorine atom, a chlorine atom, 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 a fluorine atom or a chlorine atom. In formula (2), A ＋ is a sulfonium ion, R １ , R ２ , R ３ is independently an aryl group. In formula (3), Z is an alicyclic group which may contain a nitrogen atom, a sulfur atom, or an oxygen atom, and in the alicyclic group, a hydrogen atom bonded to a carbon atom or a nitrogen atom may have a chlorine atom, a bromine atom, a fluorine atom, an iodine atom, at least one alkyl group having 1 to 15 carbon atoms, at least one alkenyloxy group having 2 to 9 carbon atoms, an aromatic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms. ＋ is an ammonium ion or a sulfonium ion. R is a chlorine atom, a bromine atom, a fluorine atom, an iodine atom, an alkyl group having 1 to 15 carbon atoms, an allyl group, an aromatic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 15 carbon atoms. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. In formula (4), A ＋ are independently an ammonium ion or a phosphonium ion; R １ , R ２ , R ３ , R ４ , R ５ , R ６ are independently an alkyl group having 1 to 6 carbon atoms, and a is an integer of 1 to 10. In formulas (1) to (4), X － is a bromine-containing ion.)

2. 2. The ruthenium treatment solution according to claim 1, wherein the quaternary onium salt is a salt of at least one ammonium ion selected from the group consisting of tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion and tetrahexylammonium ion.

3. 3. The ruthenium treatment solution according to claim 1, wherein the bromine-containing ions are bromite ions, bromate ions, perbromate ions, hypobromite ions, or bromide ions.

4. The RuO ４ 4. The ruthenium treatment solution according to claim 1, wherein the gas generation inhibitor contains an oxidizing agent different from the bromine-containing ions.

5. 5. The ruthenium treatment solution according to claim 4, wherein the oxidizing agent is an oxidizing agent containing hypochlorite ions or ozone.

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