Semiconductor wafer processing liquid containing onium salt

Abstract

Provided is a processing liquid for semiconductor wafers used in a semiconductor forming process. Provided is a processing liquid, which contains: (A) hypochlorite ions, and (B) an alkylammonium salt represented by the following formula (1). (In the formula, a is an integer from 6 to 20, and R 1 , R 2 , R 3 X is independently, for example, an alkyl group having 1 to 20 carbon atoms. ‑ For example, chloride ions.)

Description

Technical Field

[0001] The present invention relates to a novel processing liquid used in a semiconductor device manufacturing process and for etching metal ruthenium present on a semiconductor wafer. Background Art

[0002] In recent years, the miniaturization of semiconductor element design rules has led to a tendency for wiring resistance to increase. As a result of the increase in wiring resistance, the high-speed operation of semiconductor elements is increasingly hindered, and countermeasures are needed. Therefore, as a wiring material, it is desired to have a wiring material that has electromigration resistance and a lower resistance value than conventional wiring materials.

[0003] Compared with aluminum and copper, which are conventional wiring materials, ruthenium has a higher resistance to electromigration and can reduce the resistance of wiring, and has attracted much attention as a wiring material for semiconductor elements with a design rule of less than 10nm. In addition, ruthenium can prevent electromigration not only as a wiring material, but also when copper is used as a wiring material, so the use of ruthenium as a barrier metal for copper wiring is also being studied.

[0004] In the wiring forming process of semiconductor elements, even if ruthenium is selected as the wiring material, wiring can be formed by dry or wet etching as with conventional wiring materials. However, since it is difficult to remove ruthenium by dry etching using etching gas or etching using CMP grinding, more precise etching is expected, and specifically, wet etching has attracted attention.

[0005] Therefore, when using ruthenium as a wiring material or barrier metal, it is necessary to use wet etching to perform precise microfabrication of ruthenium. In order to achieve precise microfabrication of ruthenium, it is required to control the correct etching rate of ruthenium. Furthermore, in order to achieve multi-layer wiring, the flatness of each ruthenium layer is essential, and the flatness of the ruthenium surface after etching is also expected.

[0006] Patent Document 1 proposes a method for etching a ruthenium film using a solution having a pH of 12 or higher and a redox potential of 300 mV vs SHE or higher, specifically, a solution of an oxygen-containing salt of a halogen such as hypochlorite, chlorite or bromate. However, Patent Document 1 is a solution that can reliably etch away the attached ruthenium, and is a solution that aims to remove ruthenium.

[0007] In addition, Patent Document 2 proposes a method of oxidizing, dissolving, and removing ruthenium by using an aqueous solution containing orthoperiodic acid at a pH of 11 or higher. Furthermore, Patent Document 3 proposes an etching solution for ruthenium metal at a pH of 10 or higher and less than 12, comprising a bromine-containing compound, an oxidant, an alkaline compound, and water.

[0008] Patent Document 4 proposes a cleaning method in which ruthenium is oxidized, dissolved, and removed using a removing solution prepared by adding a strong acid such as nitric acid to ammonium cerium (IV) nitrate.

[0009] On the other hand, when ruthenium is wet-etched under alkaline conditions, ruthenium, for example, in the form of RuO4 - 、RuO4 2- Dissolved in the treatment solution. RuO4 - 、RuO4 2- In the treatment liquid, it changes to RuO4, and a part of it is vaporized and released into the gas phase. RuO4 is highly oxidizing, so it is not only harmful to the human body, but also easily reduced to produce RuO2 particles. Usually, particles cause a decrease in yield, so it is very problematic in the semiconductor formation process. In view of this background, it is very important to suppress the generation of RuO4 gas.

[0010] Patent Document 5 discloses a chemical solution having a pH of 12 or higher and a redox potential of 300 mV vs. SHE or higher as an etching solution for a ruthenium film. A method of etching a ruthenium film using a solution of an oxygen-containing salt of a halogen such as hypochlorite, chlorite, or bromate is also proposed.

[0011] In addition, Patent Document 6 proposes a method of oxidizing, dissolving, and removing ruthenium using an aqueous solution having a pH of 11 or higher containing orthoperiodic acid.

[0012] Patent Document 7 discloses a CMP slurry containing a ruthenium-coordinated nitrogen oxide ligand (NO ligand) that does not generate RuO 4 gas during chemical mechanical polishing (CMP) of ruthenium.

[0013] Prior art literature

[0014] Patent Literature

[0015] Patent Document 1: Japanese Patent Application Publication No. 2002-161381

[0016] Patent Document 2: International Publication No. 2016 / 068183

[0017] Patent Document 3: International Publication No. 2011 / 074601

[0018] Patent Document 4: Japanese Patent Application Publication No. 2001-234373

[0019] Patent Document 5: Japanese Patent Application Publication No. 2002-161381

[0020] Patent Document 6: International Publication No. 2016 / 068183

[0021] Patent Document 7: Japanese Patent No. 5314019 Summary of the invention

[0022] Problem that the invention aims to solve

[0023] However, the present inventors' studies have revealed that when using the conventional etching solutions described in Prior Art Documents 1 to 4, there is room for improvement in the following aspects.

[0024] For example, the method of etching ruthenium described in Patent Documents 1 and 4 aims to remove ruthenium residues attached to the back and inclined surfaces of semiconductor substrates, and can dissolve and remove ruthenium. However, when using the etching solution described in Patent Documents 1 and 4, it is difficult to maintain the flatness of the ruthenium surface after etching treatment desired in the wiring process. Therefore, when using the method described in Patent Documents 1 and 4, it is difficult to use it as an etching solution for ruthenium in the process of forming the wiring of semiconductor elements.

[0025] In addition, when using the etching solution described in Patent Document 2, similarly to Patent Document 1, it is an etching solution that targets etching residues containing ruthenium, and it is difficult to maintain the flatness of the ruthenium surface after etching, making it difficult to use in the process of forming wiring.

[0026] In addition, the etching liquid described in Patent Document 3 describes etching of ruthenium used in the manufacturing process of semiconductor elements, wiring, and barrier metals constituting substrates such as semiconductor wafers. However, similarly to Patent Documents 1 and 4, when ruthenium is etched using the etching liquid described in Patent Document 3 for the purpose of cleaning the back surface and inclined surface of substrates such as semiconductor wafers, the flatness of the ruthenium surface after etching cannot be maintained, and there is room for further improvement.

[0027] Therefore, the first object of the present invention is to provide a processing liquid capable of wet etching ruthenium present on a semiconductor wafer. A further object is to provide a processing liquid capable of maintaining the flatness of the ruthenium surface after the etching process.

[0028] Furthermore, according to the research conducted by the present inventors, it was found that when using the conventional processing liquids described in Prior Art Documents 5 to 7, there is room for improvement in the following aspects.

[0029] For example, the method for etching ruthenium described in Patent Document 5 aims to remove ruthenium residues attached to the back and inclined surfaces of a semiconductor substrate, and can dissolve and remove ruthenium. However, Patent Document 5 does not mention the suppression of RuO4 gas. In fact, when the method described in Patent Document 5 is used, the stability is lacking, a large amount of RuO4 gas is generated, and the generation of RuO4 gas cannot be suppressed. In addition, there is a problem of generating a large amount of RuO2 (particles).

[0030] In addition, Patent Document 6 discloses a composition for removing ruthenium containing orthoperiodic acid, showing that etching residues containing ruthenium can be etched. However, Patent Document 6 does not mention anything about suppressing RuO4 gas, and RuO4 gas generated during etching cannot be suppressed.

[0031] In addition, Patent Document 7 shows that toxic RuO4 gas can be suppressed by using a CMP slurry containing a ruthenium coordinated nitrogen oxide ligand (NO ligand) in CMP. However, the CMP slurry shown in Patent Document 7 is acidic, and under alkaline conditions where the dissolution mechanism of ruthenium is different, it is difficult to suppress RuO4 gas using the CMP slurry composition shown in Patent Document 7. In fact, when the ruthenium coordinated nitrogen oxide ligand described in Patent Document 7 was added to an alkaline ruthenium etching solution containing hypochlorous acid, RuO4 gas was generated, and it was confirmed that there was no RuO4 gas suppression effect.

[0032] Therefore, a second object of the present invention is to provide a processing liquid for a semiconductor wafer that can suppress the generation of RuO 4 gas when a semiconductor wafer containing ruthenium is brought into contact with a processing liquid under alkaline conditions.

[0033] Solutions for solving problems

[0034] The present inventors have conducted in-depth research to solve the above-mentioned first problem. And they have studied adding a specific alkylammonium salt to a treatment solution containing hypochlorite ions. When a treatment solution containing only hypochlorite ions is simply used, the flatness of the ruthenium surface after etching cannot be maintained, so various additives are combined. As a result, it is found that by adding a specific alkylammonium salt, the flatness of the ruthenium surface after etching can be maintained, thereby completing the first invention.

[0035] In addition, the inventors of the present invention have conducted in-depth research to solve the above-mentioned second problem. And have studied the addition of various onium salts to a semiconductor wafer treatment solution containing ruthenium. When using only a semiconductor wafer treatment solution containing ruthenium, RuO4 gas cannot be suppressed, so various additive components are combined. As a result, it is found that by adding a specific onium salt, the generation of RuO4 gas can be suppressed, thereby completing the second invention.

[0036] A first aspect of the present invention for solving the above-mentioned first problem includes the following (1) to (7).

[0037] (1) A treatment liquid used in a semiconductor forming process and for etching a metal, comprising:

[0038] (A) Hypochlorite ion,

[0039] (B) An alkylammonium salt represented by the following formula (1).

[0040]

[0041] (wherein a is an integer from 6 to 20, R 1 , R 2 , R 3 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. - is a fluoride ion, a chloride ion, an iodide ion, a hydroxide ion, a nitrate ion, a phosphate ion, a sulfate ion, a hydrogen sulfate ion, a methanesulfate ion, a perchlorate ion, an acetate ion, a fluoroborate ion, or a trifluoroacetate ion.

[0042] The mechanism by which the treatment liquid of the first embodiment of the present invention maintains the flatness of the ruthenium surface after etching is considered to be as follows. That is, the alkylammonium ions of the alkylammonium salt contained in the treatment liquid are adsorbed on the surface of ruthenium as the etching object to form a protective layer. It is believed that the protective layer formed by the alkylammonium ions will hinder the contact with the hypochlorite ions that oxidize and dissolve the ruthenium, so compared with the etching treatment using the treatment liquid containing only hypochlorite ions, the flatness of the ruthenium surface after etching can be maintained.

[0043] In addition, in the first aspect of the present invention, the following embodiments may also be adopted. In order to further suppress the roughness of the ruthenium surface after etching, it is preferred that

[0044] (2) The treatment liquid according to (1), wherein the concentration of the alkylammonium salt represented by the formula (1) in (B) is 0.0001 to 10% by mass.

[0045] Furthermore, in order to improve the etching rate of ruthenium, it is preferred

[0046] (3) The treatment liquid according to (1) or (2), wherein the concentration of the hypochlorite ions (A) is 0.05 to 20.0% by mass.

[0047] In order to reduce the amount of impurities such as sodium contained in the treatment solution, it is preferred

[0048] (4) The treatment liquid according to any one of (1) to (3), comprising (C) at least one ammonium ion selected from tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetrabutylammonium ion.

[0049] Similarly, in order to achieve both the suppression of the roughness of the ruthenium surface after etching and the etching rate of ruthenium, it is preferred

[0050] (5) The treatment liquid according to any one of (1) to (4), wherein the pH at 25° C. is more than 7 and less than 14.0.

[0051] In addition, you can also provide

[0052] (6) The processing liquid according to any one of (1) to (5), wherein the metal contained in the semiconductor wafer is ruthenium.

[0053] Furthermore, it is also possible to provide

[0054] (7) An etching method including the step of bringing the processing liquid according to any one of (1) to (6) into contact with a semiconductor wafer.

[0055] Next, a second aspect of the present invention for solving the above-mentioned second problem includes the following (8) to (23).

[0056] (8) A processing liquid for semiconductor wafers, comprising an onium salt formed of an onium ion and an anion, wherein the onium salt is a quaternary onium salt represented by formula (2) or a tertiary onium salt represented by formula (3).

[0057]

[0058]

[0059] (In formula (2), 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 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. 1 , R 2 , R 3 , R 4 In the case of an alkyl group, R 1 , R 2 , R 3 , R 4 The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the arylalkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (3), A + is the sulfonium ion, 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. 1 , R 2 , R 3 In the case of an alkyl group, R 1 , R 2 , R 3The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the aralkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (2) or (3), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion.

[0060] The mechanism by which the treatment liquid of the second embodiment of the present invention suppresses the generation of RuO4 gas is presumed to be as follows. That is, in the alkaline treatment liquid, RuO4 generated by the dissolution of ruthenium - 、RuO4 2- Anions (hereinafter sometimes referred to as RuO4 - The onium ions contained in the treatment solution (such as RuO4) interact electrostatically, and some of them exist stably in the form of ion pairs. - The change to RuO4 is inhibited, and as a result, the generation of RuO4 gas is suppressed. It is further speculated that since the generation of RuO4 is inhibited, the generation of RuO2 particles generated by the reduction of RuO4 is also suppressed.

[0061] Therefore, in the second mode of the treatment liquid of the present invention, the RuO4 gas suppression effect achieved by adding the onium salt is not limited by the type, amount, treatment method, treatment conditions, etc. of the oxidant or other additives optionally contained in the treatment liquid. For example, the oxidant optionally contained in the second mode of the treatment liquid can use an oxidant commonly known as an oxidant used in a semiconductor treatment liquid. If an example is given, halogen oxygen-containing acids, permanganate, and their salts or ions, hydrogen peroxide, ozone, cerium (IV) salts, etc. can be appropriately used. In the case of containing these oxidants, the second mode of the treatment liquid of the present invention can obtain the RuO4 gas suppression effect through the onium salt contained in the treatment liquid. In addition, the treatment method of the semiconductor wafer using the second mode of the treatment liquid of the present invention is not limited to wet etching, and can also be appropriately used as a treatment liquid for washing purposes and removing residue purposes. Furthermore, if the second mode of the treatment liquid of the present invention is used for CMP polishing, the generation of RuO4 gas can be suppressed even in the CMP polishing process. The processing of the ruthenium-containing wafer by the processing solution of the second mode of the present invention can be a single-wafer processing or an immersion processing. In addition, there is no particular restriction on the temperature of the processing solution. At any processing temperature, the onium salt contained in the processing solution can exert the RuO4 gas suppression effect.

[0062] Furthermore, in order to increase the RuO4 - In order to further suppress the generation of RuO4 gas by reducing the reactivity with onium salt, it is preferable to be as follows.

[0063] Preferred is (9) the treatment liquid according to (8), wherein the quaternary onium salt is an ammonium salt.

[0064] Preferred is (10) the treatment liquid according to (8) or (9), wherein the quaternary onium salt is a tetraalkylammonium salt.

[0065] Preferred is (11) the treatment liquid according to any one of (8) to (10), wherein the quaternary onium salt is a salt formed of at least one ammonium ion selected from tetrapropylammonium ion, tetrabutylammonium ion, or tetrapentylammonium ion.

[0066] In order to further suppress RuO4 gas by increasing the amount of onium salt added, it is preferred

[0067] (12) The treatment liquid according to any one of (8) to (11), wherein the concentration of the onium salt in the treatment liquid is 0.0001 to 50% by mass.

[0068] In order to suppress the generation of RuO2 particles and further suppress the generation of RuO4 gas, it is preferred

[0069] (13) The treatment liquid according to any one of (8) to (12), wherein the treatment liquid contains an oxidizing agent.

[0070] In order to balance the processing speed of the ruthenium-containing wafers and the suppression of RuO4 gas, it is preferred

[0071] (14) The treatment liquid according to any one of (8) to (13), wherein the treatment liquid contains hypochlorite ions, and the concentration of the hypochlorite ions is 0.05 to 20.0% by mass.

[0072] As described above, in the second embodiment of the present invention, RuO4 generated by the dissolution of ruthenium - The onium salt contained in the treatment solution is captured, thereby suppressing the generation of RuO4 gas. - The onium ions are dissolved in the treatment solution in the form of ion pairs, but when the solubility is exceeded, a precipitate is formed. The precipitate becomes a particle in the semiconductor formation process, thus causing a decrease in the yield. Therefore, in order to dissolve the precipitate, it is necessary to increase the solubility, and as a method for this, adding an organic solvent is effective. Therefore, in the second embodiment of the present invention, the following embodiment is preferably adopted. That is, the treatment solution is preferably

[0073] (15) The treatment liquid according to any one of (8) to (14), further comprising an organic solvent.

[0074] Here, when the precipitate is dissolved in the treatment solution, there are the following situations: - The state of electrical interaction between the onium ions and the like) exists in the treatment solution, and RuO4 - The interaction between the onium ions and the RuO4 is lost and each ion exists independently in the treatment solution. - etc. are captured by onium ions, so no RuO4 gas is generated. However, in the latter case, RuO4 - The former and the latter change to RuO4 and generate RuO4 gas. At this time, the difference between the former and the latter depends on the relative dielectric constant of the organic solvent added. Generally, the lower the relative dielectric constant of the solvent, the easier it is to exist in the form of ion pairs. Therefore, by adding an organic solvent with a low relative dielectric constant, the generation of RuO4 gas can be suppressed.

[0075] That is, preferably

[0076] (16) The treatment liquid according to (15), wherein the relative dielectric constant of the organic solvent is 45 or less.

[0077] Furthermore, when the treatment liquid contains a strong oxidant, it is preferred that the added organic solvent does not react with the treatment liquid.

[0078] (17) The treatment liquid according to (15) or (16), wherein the organic solvent is sulfolanes, alkyl nitriles, halogenated alkanes, or ethers.

[0079] Furthermore, in order to fully dissolve the generated precipitate, it is preferred

[0080] (18) The treatment liquid according to any one of (15) to (17), wherein the concentration of the organic solvent in the treatment liquid is 0.1 mass % or more.

[0081] In order to suppress the generation of RuO4 gas while maintaining the processing speed and storage stability of the ruthenium-containing wafer, it is preferred

[0082] (19) The treatment liquid according to any one of (8) to (18), wherein the pH at 25° C. is 7 or more and 14 or less.

[0083] It can provide

[0084] (20) The processing liquid according to any one of (8) to (19), which is used for etching a semiconductor wafer containing ruthenium.

[0085] In addition, we can provide

[0086] (21) Use of the processing liquid according to any one of (8) to (19) for etching a semiconductor wafer containing ruthenium.

[0087] It can provide

[0088] (22) A method for etching a semiconductor wafer, comprising the step of bringing the processing liquid according to any one of (8) to (19) into contact with a semiconductor wafer containing ruthenium.

[0089] It can provide

[0090] (23) A ruthenium-containing gas generation inhibitor, the ruthenium-containing gas generation inhibitor comprising an onium salt formed of an onium ion and an anion,

[0091] The onium salt is a quaternary onium salt represented by formula (2) or a tertiary onium salt represented by formula (3).

[0092]

[0093] (In formula (2), 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 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. 1, R 2 , R 3 , R 4 In the case of an alkyl group, R 1 , R 2 , R 3 , R 4 The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the arylalkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (3), A + is the sulfonium ion, 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. 1 , R 2 , R 3 In the case of an alkyl group, R 1 , R 2 , R 3 The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the aralkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (2) or (3), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion.

[0094] It can provide

[0095] (24) A method for suppressing the generation of a ruthenium-containing gas, using the inhibitor for suppressing the generation of a ruthenium-containing gas described in (23).

[0096] Furthermore, a third aspect of the present invention for solving the above-mentioned second problem includes the following (25) to (40).

[0097] (25) A processing liquid for semiconductor wafers, comprising an onium salt formed of an onium ion and an anion, wherein the onium salt is an onium salt represented by formula (4).

[0098]

[0099] (In formula (4), Z is an aromatic group or alicyclic group optionally containing nitrogen, sulfur or oxygen atoms, and in the aromatic group or the alicyclic group, carbon or nitrogen optionally has:

[0100] Chlorine, bromine, fluorine, iodine,

[0101] at least one alkyl group having 1 to 15 carbon atoms,

[0102] at least one alkenyloxy group having 2 to 9 carbon atoms,

[0103] At least one aromatic group which may be substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group which may be substituted with an alkyl group having 1 to 15 carbon atoms.

[0104] A is nitrogen or sulfur.

[0105] R is chlorine, bromine, fluorine, iodine, an alkyl group having 1 to 15 carbon atoms, an allyl group, at least one aromatic group optionally substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group optionally substituted with an alkyl group having 1 to 15 carbon atoms.

[0106] X - For organic or inorganic anions.

[0107] n is an integer of 1 or 2, indicating the number of R.

[0108] When n is 2, R may be the same or different and may form a ring.)

[0109] In addition, the present invention may also adopt the following aspects.

[0110] (26) A processing liquid for semiconductor wafers comprising an oxidizing agent and an onium salt formed of an onium ion and an anion,

[0111] The above-mentioned onium salt is an onium salt represented by formula (4).

[0112]

[0113] (In formula (4), Z is an aromatic group or alicyclic group optionally containing nitrogen, sulfur or oxygen atoms, and in the aromatic group or the alicyclic group, carbon or nitrogen optionally has:

[0114] Chlorine, bromine, fluorine, iodine,

[0115] at least one alkyl group having 1 to 15 carbon atoms,

[0116] at least one alkenyloxy group having 2 to 9 carbon atoms,

[0117] At least one aromatic group which may be substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group which may be substituted with an alkyl group having 1 to 15 carbon atoms.

[0118] A is nitrogen or sulfur.

[0119] R is chlorine, bromine, fluorine, iodine, an alkyl group having 1 to 15 carbon atoms, an allyl group, at least one aromatic group optionally substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group optionally substituted with an alkyl group having 1 to 15 carbon atoms.

[0120] X - For organic or inorganic anions.

[0121] n is an integer of 1 or 2, indicating the number of R.

[0122] When n is 2, R may be the same or different and may form a ring.)

[0123] In addition, the present invention may also adopt the following aspects.

[0124] The mechanism by which the treatment liquid of the third embodiment of the present invention suppresses the generation of RuO4 gas is presumed to be as follows. That is, in the alkaline treatment liquid, RuO4 generated by the dissolution of ruthenium - 、RuO4 2- Anions (hereinafter sometimes referred to as RuO4 - The onium ions contained in the treatment solution (such as RuO4) interact electrostatically, and some of them exist stably in the form of ion pairs. - The change to RuO4 is inhibited, and as a result, the generation of RuO4 gas is suppressed. It is further speculated that since the generation of RuO4 is inhibited, the generation of RuO2 particles generated by the reduction of RuO4 is also suppressed.

[0125] Therefore, in the treatment liquid of the third aspect of the present invention, the RuO4 gas suppression effect achieved by adding onium salts is not limited by the type, amount, treatment method, treatment conditions, etc. of the oxidant or other additives optionally contained in the treatment liquid. For example, the oxidant optionally contained in the treatment liquid can use the oxidant commonly known as the oxidant used in the semiconductor treatment liquid. If an example is given, halogen oxygen-containing acids, permanganate, and their salts or ions, hydrogen peroxide, ozone, cerium (IV) salts, etc. can be appropriately used. In the case of containing these oxidants, the treatment liquid of the third aspect of the present invention can obtain the RuO4 gas suppression effect through the onium salt contained in the treatment liquid. In addition, the treatment method of semiconductor wafers using the treatment liquid of the third aspect of the present invention is not limited to wet etching, and can also be appropriately used as a treatment liquid for washing purposes and removing residue purposes. Furthermore, if the treatment liquid of the third aspect of the present invention is used for CMP grinding, the generation of RuO4 gas can be suppressed even in the CMP grinding process. The treatment of wafers containing ruthenium using the treatment liquid of the third aspect of the present invention can be a single-wafer treatment or an immersion treatment. In addition, there is no particular limitation on the temperature of the treatment liquid. At any treatment temperature, the onium salt contained in the treatment liquid can exert the RuO4 gas suppression effect.

[0126] Furthermore, in order to increase the RuO4 - In order to further suppress the generation of RuO4 gas by reducing the reactivity with onium salt, it is preferable to be as follows.

[0127] Preferred is (27) the treatment liquid according to (25) or (26), wherein the onium salt is an imidazolium salt, a pyrrolidinium salt, a pyridinium salt, an oxazolium salt, or a piperidinium salt.

[0128] Preferably (28) is a treatment liquid according to any one of (25) to (27), wherein the above-mentioned organic or inorganic anions are fluoride ions, chloride ions, iodide ions, hydroxide ions, nitrate ions, phosphate ions, sulfate ions, hydrogen sulfate ions, methane sulfate ions, perchlorate ions, chlorate ions, chlorite ions, hypochlorite ions, orthoperiodate ions, metaperiodate ions, iodate ions, iodite ions, hypoiodite ions, acetate ions, carbonate ions, bicarbonate ions, fluoroborate ions, fluorophosphate ions, or trifluoroacetate ions.

[0129] In order to further suppress RuO4 gas by increasing the amount of onium salt added, it is preferred

[0130] (29) The treatment liquid according to any one of (25) to (28), wherein the concentration of the onium salt in the treatment liquid is 0.0001 to 50% by mass.

[0131] In order to suppress the generation of RuO2 particles and further suppress the generation of RuO4 gas, while taking into account both the processing speed of the ruthenium-containing wafer and the suppression of RuO4 gas, it is preferred

[0132] (30) The treatment liquid according to any one of (25) to (29), wherein the treatment liquid contains hypochlorite ions, and the concentration of the hypochlorite ions is 0.05 to 20.0 mass %.

[0133] As described above, in the third aspect of the present invention, RuO4 produced by dissolution of ruthenium - The onium salt contained in the treatment solution is captured, thereby suppressing the generation of RuO4 gas. - The onium ions are dissolved in the treatment solution in the form of ion pairs, but when the solubility is exceeded, a precipitate is formed. The precipitate becomes a particle in the semiconductor formation process, thus causing a decrease in the yield. Therefore, in order to dissolve the precipitate, it is necessary to increase the solubility, and as a method for this, adding an organic solvent is effective. Therefore, in the third embodiment of the present invention, the following embodiment is preferably adopted. That is, the treatment solution is preferably

[0134] (31) The treatment liquid according to any one of (25) to (30), further comprising an organic solvent.

[0135] Here, when the precipitate is dissolved in the treatment solution, there are the following situations: - The state of electrical interaction between the onium ions and the like) exists in the treatment solution, and RuO4 - The interaction between the onium ions and the RuO4 is lost and each ion exists independently in the treatment solution. - etc. are captured by onium ions, so no RuO4 gas is generated. However, in the latter case, RuO4 - The former and the latter change to RuO4 and generate RuO4 gas. At this time, the difference between the former and the latter depends on the relative dielectric constant of the organic solvent added. Generally, the lower the relative dielectric constant of the solvent, the easier it is to exist in the form of ion pairs. Therefore, by adding an organic solvent with a low relative dielectric constant, the generation of RuO4 gas can be suppressed.

[0136] That is, preferably

[0137] (32) The treatment liquid according to (31), characterized in that the relative dielectric constant of the above-mentioned organic solvent is less than or equal to 45.

[0138] Furthermore, when the treatment liquid contains a strong oxidant, it is preferred that the added organic solvent does not react with the treatment liquid.

[0139] (33) The treatment liquid according to (31) or (32), wherein the organic solvent is sulfolanes, alkyl nitriles, halogenated alkanes, or ethers.

[0140] Furthermore, in order to fully dissolve the generated precipitate, it is preferred

[0141] (34) The treatment liquid according to any one of (31) to (33), wherein the concentration of the organic solvent in the treatment liquid is 0.1 mass % or more.

[0142] In order to suppress the generation of RuO4 gas while maintaining the processing speed and storage stability of the ruthenium-containing wafer, it is preferred

[0143] (35) The treatment liquid according to any one of (25) to (34), wherein the pH at 25° C. is 7 or more and 14 or less.

[0144] Furthermore, it can provide

[0145] (36) Use of the processing liquid described in any one of (25) to (35) for etching a semiconductor wafer containing ruthenium.

[0146] It can provide

[0147] (37) A method for etching a semiconductor wafer, comprising the step of bringing the processing liquid described in any one of (25) to (35) into contact with a semiconductor wafer containing ruthenium.

[0148] Further optimization

[0149] (38) A ruthenium-containing gas generation inhibitor, comprising an onium salt formed from an onium ion and an anion, wherein the onium salt is an onium salt represented by formula (4).

[0150]

[0151] (In formula (4), Z is an aromatic group or alicyclic group optionally containing nitrogen, sulfur or oxygen atoms, and in the aromatic group or the alicyclic group, carbon or nitrogen optionally has:

[0152] Chlorine, bromine, fluorine, iodine,

[0153] at least one alkyl group having 1 to 15 carbon atoms,

[0154] at least one alkenyloxy group having 2 to 9 carbon atoms,

[0155] At least one aromatic group which may be substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group which may be substituted with an alkyl group having 1 to 15 carbon atoms.

[0156] A is nitrogen or sulfur.

[0157] R is chlorine, bromine, fluorine, iodine, an alkyl group having 1 to 15 carbon atoms, an allyl group, at least one aromatic group optionally substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group optionally substituted with an alkyl group having 1 to 15 carbon atoms.

[0158] X - For organic or inorganic anions.

[0159] n is an integer of 1 or 2, indicating the number of R.

[0160] When n is 2, R may be the same or different and may form a ring.)

[0161] Further optimization

[0162] (39) A ruthenium-containing gas generation inhibitor, comprising an oxidizing agent and an onium salt formed from an onium ion and an anion, wherein the onium salt is an onium salt represented by formula (4).

[0163]

[0164] (In formula (4), Z is an aromatic group or alicyclic group optionally containing nitrogen, sulfur or oxygen atoms, and in the aromatic group or the alicyclic group, carbon or nitrogen optionally has:

[0165] Chlorine, bromine, fluorine, iodine,

[0166] at least one alkyl group having 1 to 15 carbon atoms,

[0167] at least one alkenyloxy group having 2 to 9 carbon atoms,

[0168] At least one aromatic group which may be substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group which may be substituted with an alkyl group having 1 to 15 carbon atoms.

[0169] A is nitrogen or sulfur.

[0170] R is chlorine, bromine, fluorine, iodine, an alkyl group having 1 to 15 carbon atoms, an allyl group, at least one aromatic group optionally substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group optionally substituted with an alkyl group having 1 to 15 carbon atoms.

[0171] X - For organic or inorganic anions.

[0172] n is an integer of 1 or 2, indicating the number of R.

[0173] When n is 2, R may be the same or different and may form a ring.)

[0174] Further optimization

[0175] (40) A method for suppressing the generation of a ruthenium-containing gas, comprising using the ruthenium-containing gas generation inhibitor according to (38) or (39).

[0176] Furthermore, a fourth aspect of the present invention for solving the above-mentioned second problem includes the following (41) to (53).

[0177] (41) A semiconductor wafer processing liquid comprising an onium salt formed of an onium ion and an anion, wherein the onium salt is an onium salt represented by formula (5).

[0178]

[0179] (In formula (5), A + are independently ammonium ions or phosphonium ions, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 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. At least one hydrogen in the ring of the aryl group and the aryl group in the aralkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (5), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion, and a is an integer of 1 to 10. )

[0180] The mechanism by which the treatment liquid of the fourth embodiment of the present invention suppresses the generation of RuO4 gas is presumed to be as follows. That is, in the alkaline treatment liquid, RuO4 generated by the dissolution of ruthenium - 、RuO4 2- Anions (hereinafter sometimes referred to as RuO4 - The onium ions contained in the treatment solution (such as RuO4) interact electrostatically, and some of them exist stably in the form of ion pairs. -The change to RuO4 is inhibited, and as a result, the generation of RuO4 gas is suppressed. It is further speculated that since the generation of RuO4 is inhibited, the generation of RuO2 particles generated by the reduction of RuO4 is also suppressed.

[0181] Therefore, in the fourth mode of the treatment liquid of the present invention, the RuO4 gas suppression effect achieved by adding the onium salt is not limited by the type, amount, treatment method, treatment conditions, etc. of the oxidant or other additives optionally contained in the treatment liquid. For example, the oxidant optionally contained in the fourth mode of the treatment liquid can use an oxidant commonly known as an oxidant used in a semiconductor treatment liquid. If an example is given, halogen oxygen-containing acids, permanganate, and their salts or ions, hydrogen peroxide, ozone, cerium (IV) salts, etc. can be appropriately used. In the case of containing these oxidants, the fourth mode of the treatment liquid of the present invention can obtain the RuO4 gas suppression effect through the onium salt contained in the treatment liquid. In addition, the treatment method of the semiconductor wafer using the fourth mode of the treatment liquid of the present invention is not limited to wet etching, and can also be appropriately used as a treatment liquid for washing purposes and removing residue purposes. Furthermore, if the fourth mode of the treatment liquid of the present invention is used for CMP polishing, the generation of RuO4 gas can be suppressed even in the CMP polishing process. The processing of the ruthenium-containing wafer by the processing solution of the fourth mode of the present invention can be a single-wafer processing or an immersion processing. In addition, there is no particular restriction on the temperature of the processing solution. At any processing temperature, the onium salt contained in the processing solution can exert the RuO4 gas suppression effect.

[0182] In order to further suppress RuO4 gas by increasing the amount of onium salt added, it is preferred

[0183] (42) The treatment liquid according to (41), wherein the concentration of the onium salt in the treatment liquid is 0.0001 to 50% by mass.

[0184] In order to suppress the generation of RuO2 particles and further suppress the generation of RuO4 gas, it is preferred

[0185] (43) The treatment liquid according to (41) or (42), wherein the treatment liquid contains an oxidizing agent.

[0186] In order to balance the processing speed of the ruthenium-containing wafers and the suppression of RuO4 gas, it is preferred

[0187] (44) The treatment liquid according to any one of (41) to (43), wherein the treatment liquid contains hypochlorite ions, and the concentration of the hypochlorite ions is 0.05 to 20.0% by mass.

[0188] As described above, in the fourth aspect of the present invention, RuO4 produced by dissolution of ruthenium- The onium salt contained in the treatment solution is captured, thereby suppressing the generation of RuO4 gas. - The onium ions are dissolved in the treatment solution in the form of ion pairs, but when the solubility is exceeded, a precipitate is formed. The precipitate becomes a particle in the semiconductor formation process, thus causing a decrease in the yield. Therefore, in order to dissolve the precipitate, it is necessary to increase the solubility, and as a method for this, adding an organic solvent is effective. Therefore, in the fourth embodiment of the present invention, the following embodiment is preferably adopted. That is, the above-mentioned treatment solution is preferably

[0189] (45) The treatment liquid according to any one of (41) to (44), further comprising an organic solvent.

[0190] Here, when the precipitate is dissolved in the treatment solution, there are the following situations: - The state of electrical interaction between the onium ions and the like) exists in the treatment solution, and RuO4 - The interaction between the onium ions and the RuO4 is lost and each ion exists independently in the treatment solution. - etc. are captured by onium ions, so no RuO4 gas is generated. However, in the latter case, RuO4 - The former and the latter change to RuO4 and generate RuO4 gas. At this time, the difference between the former and the latter depends on the relative dielectric constant of the organic solvent added. Generally, the lower the relative dielectric constant of the solvent, the easier it is to exist in the form of ion pairs. Therefore, by adding an organic solvent with a low relative dielectric constant, the generation of RuO4 gas can be suppressed.

[0191] That is, preferably

[0192] (46) The treatment liquid according to (45), wherein the relative dielectric constant of the above-mentioned organic solvent is less than or equal to 45.

[0193] Furthermore, when the treatment liquid contains a strong oxidant, it is preferred that the added organic solvent does not react with the treatment liquid.

[0194] (47) The treatment liquid according to (45) or (46), wherein the organic solvent is sulfolanes, alkyl nitriles, halogenated alkanes, or ethers.

[0195] Furthermore, in order to fully dissolve the generated precipitate, it is preferred

[0196] (48) The treatment liquid according to any one of (45) to (47), wherein the concentration of the organic solvent in the treatment liquid is 0.1 mass % or more.

[0197] In order to suppress the generation of RuO4 gas while maintaining the processing speed and storage stability of the ruthenium-containing wafer, it is preferred

[0198] (49) The treatment liquid according to any one of (41) to (48), wherein the pH at 25° C. is 7 or more and 14 or less.

[0199] It can provide

[0200] (50) Use of the processing liquid described in any one of (41) to (49) for etching a semiconductor wafer containing ruthenium.

[0201] It can provide

[0202] (51) A method for etching a semiconductor wafer, comprising the step of bringing the processing liquid described in any one of (41) to (49) into contact with a semiconductor wafer containing ruthenium.

[0203] It can provide

[0204] (52) A ruthenium-containing gas generation inhibitor, comprising an onium salt formed from an onium ion and an anion, wherein the onium salt is an onium salt represented by formula (5).

[0205]

[0206] (In formula (5), A + are independently ammonium ions or phosphonium ions, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 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. At least one hydrogen in the ring of the aryl group and the aryl group in the aralkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (5), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion, and a is an integer of 1 to 10. )

[0207] Furthermore, it can provide

[0208] (53) A method for suppressing the generation of a ruthenium-containing gas, using the inhibitor for suppressing the generation of a ruthenium-containing gas described in (52).

[0209] In addition, according to the present invention which solves the second problem, it is possible to provide

[0210] (54) A treatment agent for waste liquid containing ruthenium, which is a treatment agent for waste liquid containing ruthenium, comprising an onium salt formed by an onium ion and an anion, wherein the onium salt is a quaternary onium salt represented by formula (2), a tertiary onium salt represented by formula (3), an onium salt represented by formula (4), or an onium salt represented by formula (5).

[0211]

[0212] (In formula (2), 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 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. 1 , R 2 , R 3 , R 4 In the case of an alkyl group, R 1 , R 2 , R 3 , R 4 The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the aralkyl group may be substituted 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 may be substituted with fluorine or chlorine.

[0213] In formula (3), A + is the sulfonium ion, 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. 1 , R 2 , R 3 In the case of an alkyl group, R 1 , R 2 , R 3The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the aralkyl group may be substituted 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 may be substituted with fluorine or chlorine.

[0214] In formula (2) or formula (3), X - It is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion.

[0215] In formula (4), Z is an aromatic group or alicyclic group optionally containing nitrogen, sulfur or oxygen atoms, and in the aromatic group or the alicyclic group, carbon or nitrogen optionally has:

[0216] Chlorine, bromine, fluorine, iodine,

[0217] at least one alkyl group having 1 to 15 carbon atoms,

[0218] at least one alkenyloxy group having 2 to 9 carbon atoms,

[0219] At least one aromatic group which may be substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group which may be substituted with an alkyl group having 1 to 15 carbon atoms.

[0220] A is nitrogen or sulfur.

[0221] R is chlorine, bromine, fluorine, iodine, an alkyl group having 1 to 15 carbon atoms, an allyl group, at least one aromatic group optionally substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group optionally substituted with an alkyl group having 1 to 15 carbon atoms.

[0222] X - For organic or inorganic anions.

[0223] n is an integer of 1 or 2, indicating the number of R.

[0224] When n is 2, R may be the same or different and may form a ring.

[0225] In formula (5), A + are independently ammonium ions or phosphonium ions, R 1 , R 2 , R 3 , R 4 , R 5, R 6 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. At least one hydrogen in the ring of the aryl group and the aryl group in the aralkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (5), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion, and a is an integer of 1 to 10. )

[0226] It can provide

[0227] (55) A method for treating waste liquid containing ruthenium, which uses the treating agent for waste liquid containing ruthenium described in (54).

[0228] Effects of the Invention

[0229] According to the processing liquid of the first mode of the present invention, in the formation process of the semiconductor element, ruthenium can be wet-etched, and the flatness of the ruthenium surface after the etching process can be maintained. Therefore, it can be suitably used in the case of forming a semiconductor element with a multilayer wiring structure requiring the flatness of each layer.

[0230] In addition, the treatment liquid of the first embodiment of the present invention has excellent flatness of the ruthenium surface after etching, so it can etch the ruthenium surface in contact with the treatment liquid uniformly without spots. In particular, in the formation of semiconductor elements with a wiring structure of less than 10nm that require precise ruthenium etching at the level of several nm, it can be used appropriately because the ruthenium surface in contact with the treatment liquid can be etched uniformly.

[0231] Furthermore, the processing liquid of the first aspect of the present invention can be / minute or more etching speed to etch ruthenium. An etching rate of 1000 nm / min or more can be fully used in the process of forming semiconductor devices.

[0232] On the other hand, the treatment liquid according to the second to fourth modes of the present invention can suppress the generation of ruthenium-containing gas that is the cause of particles and yield reduction in the semiconductor manufacturing process through the effect of the onium salt. In addition, since the pH range and the types of oxidants that can be selected increase, a stable treatment liquid can be achieved by selecting an appropriate oxidant. BRIEF DESCRIPTION OF THE DRAWINGS

[0233] Figure 1 It is a schematic cross-sectional view showing an example of a wiring forming process to which the processing liquid of the first embodiment of the present invention can be preferably applied.

[0234] Figure 2 It is a schematic cross-sectional view showing an example of a wiring forming step after treatment with the treatment liquid according to the first embodiment of the present invention.

[0235] Figure 3 This is a photograph obtained by observing the ruthenium surface after the etching process shown in Example 1 using an electron microscope at a magnification of 100,000 times. DETAILED DESCRIPTION

[0236] In this specification, ruthenium (also described as Ru) is not limited to ruthenium metal, and any ruthenium element may be contained.

[0237] (Treatment liquid of the first embodiment)

[0238] The processing liquid of the first embodiment of the present invention is a processing liquid that can etch ruthenium present on the semiconductor wafer without damaging the semiconductor wafer. Therefore, the processing liquid of the first embodiment of the present invention is a processing liquid that can be suitably used in the wiring formation process in the semiconductor manufacturing process.

[0239] The ruthenium in the processing liquid according to the first embodiment of the present invention is mainly formed by a known method such as CVD, ALD, sputtering, etc. used in a semiconductor device process, and the formed ruthenium is etched to form wiring in the semiconductor. Figure 1 , 2 An example of a wiring forming process is shown.

[0240] First, a substrate 1 formed of a semiconductor (e.g., Si) is prepared. The prepared substrate is subjected to oxidation treatment to form a silicon oxide film on the substrate. Then, an interlayer insulating film 2 formed of a low dielectric constant (Low-k) film is formed, and through holes are formed at predetermined intervals. After the formation, ruthenium 3 is buried in the through holes by thermal CVD to form a ruthenium film ( Figure 1 ). For this, the ruthenium film is etched by dry etching or wet etching to be flattened, forming a ruthenium wiring ( Figure 2 ).

[0241] The treatment liquid of the first aspect of the present invention contains (A) hypochlorite ions and (B) an alkylammonium salt represented by the following formula (1).

[0242]

[0243] (wherein a is an integer from 6 to 20, R 1 , R 2 , R 3 X is independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. - is a fluoride ion, a chloride ion, an iodide ion, a hydroxide ion, a nitrate ion, a phosphate ion, a sulfate ion, a hydrogen sulfate ion, a methanesulfate ion, a perchlorate ion, an acetate ion, a fluoroborate ion, or a trifluoroacetate ion.

[0244] (A) Hypochlorite ion

[0245] The hypochlorite ions used in the first aspect of the present invention can be generated by dissolving hypochlorite in water to generate hypochlorous acid and hypochlorite ions. Hypochlorite ions are oxidants with strong oxidizing properties, and the processing liquid of the present invention containing hypochlorite ions can etch metals contained in semiconductor wafers.

[0246] In the first aspect of the present invention, the range of the hypochlorite ion concentration is preferably 0.05 to 20% by mass relative to the total treatment liquid. If it is within the above range, the decomposition reaction of the hypochlorite ions in the treatment liquid can be suppressed, and the reduction of the hypochlorite ion concentration can be suppressed (hereinafter, the effect of suppressing the decomposition reaction of the hypochlorite ions in the treatment liquid and suppressing the reduction of the hypochlorite ion concentration is sometimes referred to as "good storage stability"). Therefore, the hypochlorite ion concentration is preferably in the range of 0.1 to 15 mass %, more preferably 0.3 to 10 mass %, further preferably 0.5 to 6 mass %, and particularly preferably 0.5 to 4 mass %.

[0247] In addition, the concentration of hypochlorite ions in the treatment liquid of the first embodiment of the present invention can also be calculated when the treatment liquid is manufactured, or it can be confirmed by directly analyzing the treatment liquid. The concentration of hypochlorite ions recorded in the following embodiments is obtained by measuring the effective chlorine concentration of the treatment liquid. Specifically, referring to Notice No. 318 of the Ministry of Health, Labor and Welfare of Japan (finally revised on March 11, 2007), potassium iodide and acetic acid are added to a solution containing hypochlorite ions, and the free iodine is subjected to redox titration using an aqueous sodium thiosulfate solution to calculate the effective chlorine concentration. The calculated effective chlorine concentration is converted to the hypochlorite ion concentration of the present invention.

[0248] (B) Alkyl ammonium salt represented by the following formula (1)

[0249] The alkylammonium salt contained in the treatment liquid of the first aspect of the present invention is an alkylammonium salt represented by the following formula (1).

[0250]

[0251] (wherein a is an integer from 6 to 20, R 1 , R 2 , R 3 X is independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. - is a fluoride ion, a chloride ion, an iodide ion, a hydroxide ion, a nitrate ion, a phosphate ion, a sulfate ion, a hydrogen sulfate ion, a methanesulfate ion, a perchlorate ion, an acetate ion, a fluoroborate ion, or a trifluoroacetate ion.

[0252] In the above formula (1), the integer a represents the number of methylene groups. If the integer a is 6 to 20, it can be used without particular limitation, but the integer a is more preferably 6 to 15, and the integer a is further preferably 8 to 13. If it is an alkylammonium salt having a methylene group within the above range, it can be used appropriately because it forms a suitable protective layer by adsorption on the ruthenium surface. In addition, the larger the integer a of the alkylammonium salt, the more the adsorption amount of the alkylammonium ions of the alkylammonium salt on the ruthenium surface increases, so there is a tendency for the etching rate of ruthenium to decrease. On the other hand, the smaller the integer a of the alkylammonium salt, the less the adsorption amount on the ruthenium surface, and it is not possible to form a suitable protective layer on the ruthenium surface, and there is a tendency that the flatness of the ruthenium surface after etching cannot be maintained.

[0253] If the integer a of the alkylammonium salt is large, the water solubility of the alkylammonium salt decreases, which causes particles to form in the treatment solution. If particles remain on the ruthenium surface after etching, the yield of the semiconductor device decreases, so it is preferred to have fewer particles. Considering the adsorption to the ruthenium surface and the water solubility to the treatment solution, it is more preferred that the integer a in the above formula (1) is 6 to 15, and it is further preferred that the integer a is 8 to 13.

[0254] In addition, R in the above formula (1) 1 , R 2 , R 3 R is independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and may be the same or different. 1 , R 2 , R 3 It is preferably an alkyl group having 1 to 20 carbon atoms. 1 , R 2 , R 3 The carbon number of each of the integers a is preferably the same as or smaller than the integer a, and more preferably R 1 , R2 , R 3 It is preferred that any one of them is methyl. 1 , R 2 , R 3 If any one of them is a methyl group, a more uniform and dense protective layer is formed on the ruthenium surface, and the flatness of the ruthenium surface after etching can be maintained.

[0255] In the above formula (1), X - It is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, hydrogen sulfate ion, methane sulfate ion, perchlorate ion, acetate ion, fluoroborate ion, or trifluoroacetate ion. In the present invention, the anion of the alkylammonium salt can be used as the treatment liquid without particular limitation.

[0256] The mechanism by which the treatment liquid of the first mode of the present invention can maintain the flatness of the ruthenium surface after etching is considered to be as follows. That is, it is believed that the cations (alkylammonium ions) of the alkylammonium salt contained in the treatment liquid are partially adsorbed on the polar group with the nitrogen atom as the center on the ruthenium surface. The alkyl group, which is the non-polar group of the adsorbed cation, is located in a direction away from the ruthenium surface, forming a hydrophobic protective layer on the ruthenium surface. The formed protective layer prevents the hypochlorite ions contained in the treatment liquid from contacting with ruthenium, so as a result, a uniform etching process of ruthenium without spots can be performed, and the flatness of the ruthenium surface after etching is maintained.

[0257] In the first embodiment of the present invention, if the alkylammonium salt represented by formula (1) that can be specifically used is listed, there can be mentioned n-octyltrimethylammonium chloride, decyltrimethylammonium chloride, lauryltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, didecyldimethylammonium chloride, didodecyldimethylammonium chloride, tetraheptylammonium chloride, etc.

[0258] In addition, the amount of the alkylammonium salt added is preferably in the range of 0.001 to 10 mass % relative to the total treatment solution. If it is within this range, the etching rate of ruthenium will not decrease and a sufficient protective layer can be formed on the ruthenium surface. It should be noted that when adding an alkylammonium salt, only one type can be added or two or more types can be mixed to add.

[0259] In the treatment liquid of the first embodiment of the present invention, the remaining part except (A), (B), (C) described in detail below and other additives is water. The water contained in the treatment liquid of the present invention is preferably water from which metal ions, organic impurities, particles, etc. are removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and pure water and ultrapure water are particularly preferred.

[0260] (C) Ammonium ion

[0261] In the treatment liquid of the first embodiment of the present invention, hypochlorite ions are contained in the treatment liquid by dissolving hypochlorite in water, etc., so the counter ions of hypochlorite ions are contained in the treatment liquid. Usually, hypochlorite is sodium hypochlorite, calcium hypochlorite, etc., and in this case, sodium ions and calcium ions are contained as counter ions.

[0262] And when the alkali metal ions and alkaline earth metal ions such as the above-mentioned sodium ion and calcium ion remain on the semiconductor wafer, the semiconductor wafer is adversely affected (adverse effects such as the yield rate of the semiconductor wafer is reduced), so its blending ratio is preferably less, and it is advisable to not contain it infinitely in fact. Therefore, as the counter ion of hypochlorite ion, it is preferably the counter ion of organic system. If industrial manufacturing is considered, it is preferably selected from at least one ammonium ion in tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetrabutylammonium ion, and tetramethylammonium ion is particularly preferred. Therefore, as the counter ion, tetramethylammonium ion is selected, and the sodium ion and calcium ion in the treatment solution can be reduced, so it is preferred that the treatment solution contains tetramethylammonium ion. In addition, it can also be contained in the form of tetramethylammonium hydroxide and tetramethylammonium hydroxide salt.

[0263] In the first embodiment of the present invention, the concentration range of ammonium ions is preferably 0.1 to 30% by mass relative to the total treatment solution. When the concentration of ammonium ions satisfies this range, a treatment solution having excellent long-term storage stability can be formed. In order to further improve storage stability, the concentration of ammonium ions is more preferably 0.15 to 20% by mass, further preferably 0.3 to 15% by mass, and particularly preferably 0.5 to 8% by mass.

[0264] In the first embodiment of the present invention, for tetramethylammonium ions, for example, an aqueous solution of tetramethylammonium hydroxide is passed through an ion exchange resin to prepare an ion exchange resin that is exchanged for tetramethylammonium ions, and then contacted with a solution containing hypochlorite ions to perform ion exchange with cations contained in the solution, thereby allowing tetramethylammonium ions to be contained in the treatment solution.

[0265] The treatment liquid of the first embodiment of the present invention preferably has a pH greater than 7 and less than 14. When the pH of the treatment liquid is less than 7, a decomposition reaction of hypochlorite ions is likely to occur, and there is a tendency for the hypochlorite ion concentration to decrease easily. Therefore, in order to take into account both the storage stability of the treatment liquid and the etching rate of ruthenium, the pH of the treatment liquid is preferably greater than 7 and less than 14, more preferably greater than 8 and less than 11. For example, if it is within the above range, the hypochlorite ion concentration is not easy to decrease during storage, for example, a treatment liquid can be formed in which the etching performance of ruthenium is fully exerted even after being stored in a dark place at 23°C and an inert gas atmosphere for 15 days. It should be noted that in this specification, pH is recorded as a value at 25°C.

[0266] (Other additives)

[0267] In addition, the treatment liquid of the first embodiment of the present invention may be mixed with other additives conventionally used in semiconductor treatment liquids as needed within the range that does not impair the purpose of the present invention. For example, other additives may include acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidants, reducing agents, complexing agents, chelating agents, nonionic surfactants, defoaming agents, pH adjusters, etc.

[0268] Originating from these other additives or in the manufacture of the treatment solution, the treatment solution of the present invention may contain alkali metal ions and alkaline earth metal ions, such as sodium ions and calcium ions. However, as mentioned above, when these alkali metal ions and alkaline earth metal ions remain on the semiconductor wafer, they have an adverse effect on the semiconductor wafer (adverse effects such as reduced yield of the semiconductor wafer), so the mixing ratio is preferably small, and it is actually appropriate to contain no ions indefinitely. Therefore, for example, as a pH adjuster, an organic base such as tetraalkylammonium hydroxide is preferably used, rather than an alkali metal hydroxide or an alkaline earth metal hydroxide such as sodium hydroxide.

[0269] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1 mass % or less, more preferably 0.7 mass % or less, further preferably 0.3 mass % or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0270] (Method for producing treatment liquid according to the first aspect)

[0271] Next, the processing liquid and the like according to the first aspect of the present invention will be described.

[0272] The treatment liquid of the first embodiment of the present invention can be produced by adding and mixing an alkylammonium salt to an aqueous hypochlorite solution containing hypochlorite ions. The hypochlorous acid aqueous solution can be produced by dissolving a commercially available hypochlorite such as sodium hypochlorite or calcium hypochlorite in water; and blowing chlorine into an alkaline aqueous solution such as a sodium hydroxide solution or a tetramethylammonium hydroxide aqueous solution. In addition, for example, by contacting an aqueous sodium hypochlorite solution with an ion exchange resin that forms a tetramethylammonium type, the counter ion of the hypochlorite ion can be exchanged.

[0273] A method for producing a treatment liquid according to a first embodiment of the present invention using an aqueous sodium hypochlorite solution as an aqueous tetramethylammonium hypochlorite solution is described in detail below. This method utilizes a method for producing a treatment liquid using an aqueous hypochlorite solution in which a counter ion of hypochlorite ions is exchanged with an ion exchange resin.

[0274] First, an aqueous solution containing tetramethylammonium ions, specifically, an aqueous solution of tetramethylammonium hydroxide, is brought into contact with an ion exchange resin to prepare an ion exchange resin in a tetramethylammonium type.

[0275] The ion exchange resin used can be used without particular restrictions if it is a known cation exchange resin. For example, hydrogen-type ion exchange resin, sodium-type ion exchange resin, etc. can be used. Among them, hydrogen-type ion exchange resins with low possibility of sodium mixing are preferred. In addition, for hydrogen-type ion exchange resins, etc., weakly acidic and strongly acidic ion exchange resins can be used without particular restrictions.

[0276] After the tetramethylammonium type ion exchange resin is prepared, the ion exchange resin is brought into contact with an aqueous hypochlorite solution, thereby producing an aqueous tetramethylammonium hypochlorite solution.

[0277] The sodium hypochlorite aqueous solution can be prepared by dissolving sodium hypochlorite in water. In addition, here, sodium hypochlorite is used from the viewpoint of good storage stability and operability, but calcium hypochlorite or the like may also be used if it is a commercially available product and is easily available.

[0278] In addition, the ion exchange step may be repeated. By repeating the ion exchange step, the metal ions such as sodium and calcium that serve as counter ions of hypochlorite ions contained in the tetramethylammonium hypochlorite aqueous solution can be reduced.

[0279] By mixing and dissolving an alkylammonium salt and, if necessary, other additives in the obtained tetramethylammonium hypochlorite aqueous solution, it is possible to produce the treatment liquid of the present invention containing tetramethylammonium ions.

[0280] (Ruthenium etching method)

[0281] The etching conditions using the processing liquid of the first aspect of the present invention are in the range of a temperature of 10 to 80° C., preferably 20 to 70° C., and may be appropriately selected in accordance with the etching conditions of the etching apparatus used.

[0282] In addition, the etching rate of ruthenium varies with temperature. Therefore, in order to improve the etching rate of ruthenium, it is appropriate to select 40 to 70°C in the above temperature range. If the temperature is within the range of 40 to 70°C, the etching rate can be accelerated, and the process can be performed with a simple device and good operability.

[0283] The time for using the treatment solution of the present invention is 0.1 to 120 minutes, preferably in the range of 0.5 to 60 minutes, which can be appropriately selected according to the etching conditions and the semiconductor element used. As a rinse liquid after using the treatment solution of the present invention, although an organic solvent such as alcohol can also be used, it is sufficient to rinse with deionized water alone.

[0284] As described above, the processing liquid of the first embodiment of the present invention can make the etching rate of ruthenium / minute or more, preferred / minute or more, and the flatness of the ruthenium surface after etching is excellent. It can be seen from this that the processing liquid of the present invention can be used appropriately when ruthenium is used in the semiconductor element formation process.

[0285] (Processing liquid of the second embodiment)

[0286] Next, the processing liquid and the like according to the second aspect of the present invention will be described.

[0287] The processing liquid of the second embodiment of the present invention is a processing liquid that can process a semiconductor wafer containing ruthenium without generating RuO4 gas. Therefore, the processing liquid of the second embodiment of the present invention is a processing liquid that can be suitably used in an etching process, a residue removal process, a washing process, a CMP process, etc. in a semiconductor manufacturing process.

[0288] The ruthenium contained in the semiconductor wafer to which the treatment liquid of the second mode of the present invention is applicable can be formed by any method. The film formation of ruthenium can utilize methods widely known in the semiconductor manufacturing process, such as CVD, ALD, sputtering, plating, etc. These rutheniums can be metallic ruthenium, or ruthenium oxides, alloys with other metals, intermetallic compounds, ionic compounds, and complexes. In addition, ruthenium can be exposed on the surface of the wafer, or covered by other metals, metal oxide films, insulating films, resists, etc. Even when covered by other materials, when ruthenium contacts the treatment liquid and dissolution of ruthenium occurs, the onium salt contained in the treatment liquid of the second mode of the present invention can also exert the inhibitory effect of RuO4 gas generation. Furthermore, even when the treatment liquid of the second mode of the present invention does not actively dissolve ruthenium, that is, when ruthenium is the object of protection during processing, the RuO4 gas generated by the very little ruthenium dissolved can be suppressed.

[0289] For example, in the ruthenium wiring formation process, the case of using the processing liquid of the second mode of the present invention is as follows. First, a substrate formed of a semiconductor (such as Si) is prepared. The prepared substrate is subjected to oxidation treatment and a silicon oxide film is formed on the substrate. Then, an interlayer insulating film formed of a low dielectric constant (Low-k) film is formed, and through holes are formed at specified intervals. After the through holes are formed, ruthenium is buried in the through holes by thermal CVD to form a ruthenium film. The ruthenium film is etched using the processing liquid of the present invention, thereby suppressing the generation of RuO4 gas while flattening it. Thus, a ruthenium wiring with high reliability in which RuO2 particles are suppressed can be formed.

[0290] The processing liquid of the second aspect of the present invention contains an onium salt formed of an onium ion and an anion.

[0291] The onium salt is represented by the following formula (2) or (3).

[0292]

[0293] (In formula (2), 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 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. 1 , R 2 , R 3 , R 4 In the case of an alkyl group, R 1 , R 2 , R 3 , R 4 The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the arylalkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (3), A + is the sulfonium ion, 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. 1 , R 2 , R 3 In the case of an alkyl group, R 1 , R 2 , R 3 The carbon number of at least one alkyl group in the aryl group is 2 or more. In addition, at least one hydrogen in the ring of the aryl group in the aryl group and the aralkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (2) or (3), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion.

[0294] If R in the above formula (2) or (3) 1 , R 2 , R 3 , R 4The alkyl groups independently have carbon numbers of 1 to 25 and can be used without particular limitation. - On the other hand, the larger the carbon number, the more bulky the onium ions are, so the RuO4 gas is easily suppressed. - The more electrostatic interactions are generated, the less ion pairs are dissolved in the treatment solution, and a precipitate is generated. The precipitate forms particles and causes a decrease in the yield of semiconductor components. In addition, the greater the carbon number, the lower the solubility in the treatment solution, and the easier it is to generate bubbles in the treatment solution. On the contrary, if the carbon number is small, the onium ions and RuO4 - The interaction of the above mentioned is weakened, and thus the RuO4 gas suppression effect is weakened. Therefore, the carbon number of the alkyl group in formula (2) or (3) is preferably independently 1 to 25, more preferably 2 to 10, and most preferably 3 to 6. 1 , R 2 , R 3 , R 4 In the case of an alkyl group, R 1 , R 2 , R 3 , R 4 The carbon number of at least one alkyl group in the formula (3) may be 3 or more. 1 , R 2 , R 3 In the case of an alkyl group, R 1 , R 2 , R 3 The carbon number of at least one alkyl group in the above-mentioned can be 3 or more. If the onium salt of an alkyl group having such a carbon number is used, the onium salt is reacted with RuO4 - The interaction of the above mentioned substances can suppress the generation of RuO4 gas and makes it difficult to generate precipitates, so it can be suitably used as a semiconductor processing liquid.

[0295] In the above formula (2) or (3), R 1 , R 2 , R 3 , R 4 The aryl group independently includes not only aromatic hydrocarbons but also heteroaryl groups containing hetero atoms, and although not particularly limited, is preferably a phenyl group or a naphthyl group.

[0296] In the above formula (2) or formula (3), X -If it is an anion, there is no particular limitation, but preferably it is a fluoride ion, a chloride ion, an iodide ion, a hydroxide ion, a nitrate ion, a phosphate ion, a sulfate ion, a hydrogen sulfate ion, a methanesulfate ion, a perchlorate ion, a chlorate ion, a chlorite ion, a hypochlorite ion, an orthoperiodate ion, a metaperiodate ion, an iodate ion, an iodite ion, a hypoiodite ion, an acetate ion, a carbonate ion, a hydrogen carbonate ion, a fluoroborate ion, or a trifluoroacetate ion.

[0297] The mechanism by which the treatment liquid of the second embodiment of the present invention suppresses RuO4 gas is considered to be as follows. That is, RuO4 generated by the dissolution of ruthenium - The trapped RuO4 - It exists relatively stably in the treatment liquid in the form of ion pairs, so it is not easy to change into RuO4. As a result, the generation of RuO4 gas is suppressed and the generation of RuO2 particles is also suppressed.

[0298] The quaternary onium salt shown in the above formula (2) is a salt formed by ammonium ions or phosphonium ions that can stably exist in the treatment solution, i.e., an ammonium salt or a phosphonium salt. Usually, the alkyl chain length of the ammonium ion or the phosphonium ion can be easily controlled, and then it is also easy to import allyl groups and aryl groups. Thus, the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surface activity performance, etc. of the ammonium ion or the phosphonium ion can be controlled, and the ammonium salt or the phosphonium salt formed by the ion can also control its size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, surface activity performance, etc. This ammonium salt or phosphonium salt can be used as the quaternary onium salt shown in the formula (2) of the treatment solution of the second mode of the present invention.

[0299] The tertiary onium salt shown in the above formula (3) is a salt formed by a sulfonium ion that can stably exist in the treatment solution, i.e., a sulfonium salt. Usually, the alkyl chain length of the sulfonium ion can be easily controlled, and it is also easy to introduce allyl groups and aryl groups. Thus, the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surface activity, etc. of the sulfonium ion can be controlled, and the sulfonium salt formed by the ion can also control its size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, surface activity, etc. This sulfonium salt can be used as the tertiary onium salt shown in formula (3) of the treatment solution of the second embodiment of the present invention.

[0300] The quaternary onium salt contained in the treatment liquid of the second aspect of the present invention is preferably an ammonium salt because of its high stability, easy industrial availability of a high-purity product, and low cost.

[0301] The quaternary onium salt is preferably a tetraalkylammonium salt which is particularly excellent in stability and can be easily synthesized. The tetraalkylammonium salt is more preferably a hydroxide or a halide.

[0302] In the second embodiment of the present invention, as the quaternary onium salt that can be suitably used, ammonium salts formed by tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, or tetrahexylammonium ion can be listed. Furthermore, these salts are more preferably hydroxides or halides. The processing liquid containing these quaternary onium salts can suppress RuO4 gas and perform processing without the generation of RuO2 particles, especially in the processing of semiconductor wafers.

[0303] In addition, the concentration of the onium salt in the treatment solution of the second embodiment of the present invention is preferably 0.0001 to 50% by mass. If the amount of onium salt added is too small, not only RuO4 - The interaction between the RuO4 and the like is weakened, the RuO4 gas suppression effect is reduced, and the RuO4 that can be dissolved in the treatment solution - The amount of etc. is reduced, so the number of reuses of the treatment solution is reduced. On the other hand, if the addition amount is too much, the adsorption amount of the onium salt on the ruthenium surface increases, which becomes the cause of the reduced ruthenium dissolution rate and uneven etching of the ruthenium surface. Therefore, the treatment solution of the second embodiment of the present invention preferably contains 0.0001 to 50% by mass of onium salt, more preferably 0.01 to 35% by mass, and further preferably 0.1 to 20% by mass. It should be noted that when adding an onium salt, only one or a combination of two or more can be added. Even if it contains more than two onium salts, if the total concentration of the onium salt is within the above concentration range, the generation of RuO4 gas can be effectively suppressed.

[0304] (Oxidant)

[0305] The treatment liquid of the second mode of the present invention may contain an oxidant. As the oxidant, for example, halogen oxygen-containing acids, permanganic acid and their salts, hydrogen peroxide, ozone, cerium (IV) salts, etc. can be listed, but are not limited to them. Here, halogen oxygen-containing acid refers to hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypoiodous acid, iodous acid, iodic acid, metaperiodic acid, orthoperiodic acid or their ions. By containing an oxidant, the dissolution of ruthenium is promoted, and the redissolution of the precipitated RuO2 particles is promoted. Therefore, the treatment liquid containing onium salts and oxidants can suppress the generation of RuO4 gas and RuO2 particles, and effectively process wafers containing Ru. Among the above-mentioned oxidants, from the viewpoint of being alkaline and stable to use, and being able to widely select the concentration range, halogen oxygen-containing acids and their ions, or hydrogen peroxide are suitable as oxidants, more preferably hypochlorous acid, metaperiodic acid, orthoperiodic acid and their ions, and most preferably hypochlorous acid and hypochlorite ions.

[0306] In the case where the treatment liquid of the second embodiment of the present invention is a treatment liquid containing hypochlorite ions, the concentration of the hypochlorite ions is preferably in the range of 0.05 to 20.0% by mass relative to the entire treatment liquid. If it is within the above range, the decomposition reaction of the hypochlorite ions in the treatment liquid is suppressed, and the concentration of the hypochlorite ions is suppressed from decreasing, and the treatment liquid can be treated with Therefore, the concentration of hypochlorite ions is preferably in the range of 0.1 to 15% by mass, more preferably 0.3 to 10% by mass, further preferably 0.5 to 6% by mass, and particularly preferably 0.5 to 4% by mass.

[0307] In the treatment liquid of the second embodiment of the present invention, the residual part except the onium salt, the organic solvent described in detail below and other additives is water. The water contained in the treatment liquid of the second embodiment of the present invention is preferably water from which metal ions, organic impurities, particles, etc. are removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and pure water and ultrapure water are particularly preferred. Such water can be obtained by a known method widely used in semiconductor manufacturing.

[0308] (Organic Solvent)

[0309] As described above, in the second embodiment of the present invention, RuO4 generated when ruthenium is dissolved - The RuO4 gas is retained in the treatment solution by the electrostatic interaction with the onium ions, thereby suppressing the generation of RuO4 gas. - The isocyanate ions are dissolved in the solution in the form of ion pairs, but when the solubility is exceeded, a precipitate is formed. The precipitate is the main cause of particles in the semiconductor formation process, thus resulting in a reduction in yield. Therefore, it is important not to produce a precipitate, and it is preferred to increase the solubility of the ion pair. As this method, adding an organic solvent is effective.

[0310] Generally, the lower the relative dielectric constant of the solvent, the easier it is to dissolve electrically neutral chemical species. When the relative dielectric constant of the solvent is low, electrically neutral ion pairs are also easily dissolved. Therefore, in order to increase the solubility of ion pairs, it is preferred to add an organic solvent having a lower relative dielectric constant than water (relative dielectric constant 78) as the organic solvent added to the treatment liquid of the second embodiment of the present invention. In this way, the relative dielectric constant of the treatment liquid can be lowered compared to the case of only water, and the onium ion and RuO4 can be increased. - The solubility of ion pairs such as RuO4 can effectively suppress the generation of RuO4 gas. As the added organic solvent, any organic solvent can be used as long as it has a relative dielectric constant lower than that of water, but the relative dielectric constant is preferably 45 or less, more preferably 20 or less, and further preferably 10 or less. It should be noted that these relative dielectric constants are values ​​at 25°C.

[0311] Specific examples of such organic solvents include sulfolane (relative dielectric constant 43), acetonitrile (relative dielectric constant 37), carbon tetrachloride (relative dielectric constant 2.2), and 1,4-dioxane (relative dielectric constant 2.2), but the organic solvent is of course not limited to these.

[0312] When an organic solvent with a low relative dielectric constant is added, it may not be easily mixed with water. However, even in this case, the solubility of the ion pair can be increased by using an organic solvent that is slightly soluble in water, and the addition of an organic solvent is effective in suppressing the generation of RuO4 gas.

[0313] When the treatment liquid contains an oxidant, in order to prevent the organic solvent from being decomposed by the oxidant, it is preferred that the two do not react, but any organic solvent can be used if the reactivity with the oxidant is low. If an example is given, when the oxidant is hypochlorite ions, sulfolanes, alkyl nitriles, halogenated alkanes, ethers, etc. have low reactivity with hypochlorite ions, and therefore, can be suitably used as organic solvents added to the treatment liquid of the second embodiment of the present invention. If such organic solvents are specifically listed, they are sulfolane, acetonitrile, carbon tetrachloride, 1,4-dioxane, etc., but of course the organic solvent is not limited to them.

[0314] The organic solvent can be added in an amount required to suppress the formation of precipitates. Therefore, the concentration of the organic solvent in the treatment liquid of the second embodiment of the present invention can be 0.1 mass % or more, but in order to increase the amount of ion pairs dissolved, RuO4 - The organic solvent is stably maintained in the solution in the form of ion pairs, and the concentration of the organic solvent is preferably 1% by mass or more. In addition, if it is within the range that does not damage the solubility of ruthenium and the storage stability of the treatment solution, the more the amount of organic solvent added, the more the amount of ion pairs that can be dissolved in the treatment solution increases, so not only can the generation of precipitates be suppressed, but also the RuO4 gas suppression effect will not decrease even if the organic solvent evaporates in small amounts, and the generation of RuO4 gas can be suppressed even when the treatment solution is reused, etc., which has many advantages. Furthermore, the added organic solvent can be added in one or a combination of multiple types.

[0315] If a highly volatile solvent is used as the organic solvent, the organic solvent in the processing solution evaporates during the processing of the semiconductor wafer, so the concentration of the organic solvent changes and the relative dielectric constant of the processing solution changes, making it difficult to perform stable processing. In addition, from the viewpoint of storage stability, it is also preferred that the volatility of the organic solvent is low. Specifically, an organic solvent having a vapor pressure of 50 mmHg or less at 20°C is preferred, and an organic solvent having a vapor pressure of 20 mmHg or less is more preferred.

[0316] The treatment liquid of the second embodiment of the present invention preferably has a pH of 7 or more and 14 or less at 25°C. When the pH of the treatment liquid is less than 7, ruthenium dissolves via RuO2 and Ru(OH)3, rather than via RuO4. - Therefore, the effect of adding cations is reduced. Furthermore, when the pH is less than 7, RuO2 particles are easily generated, and the problem of increased generation of RuO4 gas also occurs. Therefore, in order for the second method of the treatment liquid of the present invention to fully exert the ability to inhibit the generation of RuO4 gas, the pH of the treatment liquid is preferably 7 or more and 14 or less, more preferably 9 or more and 13 or less. If it is within this pH range, the ruthenium dissolved in the treatment liquid is RuO4 - or RuO4 2- It exists in the form of anions, so it is easy to form ion pairs with the onium ions contained in the treatment liquid of the second embodiment of the present invention, and can effectively suppress the generation of RuО4 gas.

[0317] (Other additives)

[0318] The treatment liquid of the second embodiment of the present invention may be mixed with other additives that have been used in semiconductor treatment liquids as needed within the scope that does not impair the purpose of the present invention. For example, as other additives, acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidants, reducing agents, complexing agents, chelating agents, surfactants, defoaming agents, pH adjusters, stabilizers, etc. may be added. These additives may be added alone or in combination.

[0319] The second embodiment of the present invention may contain alkali metal ions, alkaline earth metal ions, etc., such as sodium ions, potassium ions, calcium ions, etc., due to these other additives or due to reasons in the manufacture of the treatment liquid. However, when these alkali metal ions and alkaline earth metal ions remain on the semiconductor wafer, they have an adverse effect on the semiconductor element (adverse effects such as reduced yield of semiconductor wafers), so the amount is preferably small, and it is better to contain no ions in fact. Therefore, for example, as a pH adjuster, organic bases such as ammonia, amines, choline or tetraalkylammonium hydroxide are preferred, rather than alkali metal hydroxides such as sodium hydroxide and alkaline earth metal hydroxides.

[0320] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1 mass % or less, more preferably 0.7 mass % or less, further preferably 0.3 mass % or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0321] (Third-party treatment fluid)

[0322] Next, the processing liquid and the like according to the third embodiment of the present invention will be described.

[0323] The third embodiment of the present invention is a treatment liquid that can process semiconductor wafers containing ruthenium without generating RuO4 gas. Therefore, the third embodiment of the present invention is a treatment liquid that can be suitably used in etching steps, residue removal steps, washing steps, CMP steps, etc. in semiconductor manufacturing steps.

[0324] The ruthenium contained in the semiconductor wafer to which the treatment solution of the third aspect of the present invention is applicable can be formed by any method. The film formation of ruthenium can utilize methods widely known in the semiconductor manufacturing process, such as CVD, ALD, sputtering, plating, etc. These rutheniums can be metallic ruthenium, or ruthenium oxides, alloys with other metals, intermetallic compounds, ionic compounds, and complexes. In addition, ruthenium can be exposed on the surface of the wafer, or covered by other metals, metal oxide films, insulating films, resists, etc. Even when covered by other materials, when ruthenium contacts the treatment solution and dissolution of ruthenium occurs, the onium salt contained in the treatment solution of the third aspect of the present invention can also exert the inhibitory effect of RuO4 gas production. Furthermore, even when the treatment solution of the present invention does not actively dissolve ruthenium, that is, when ruthenium is the object of protection during processing, the RuO4 gas produced by the very little ruthenium dissolved can be suppressed.

[0325] For example, in the ruthenium wiring formation process, the situation of using the third embodiment of the present invention is as follows. First, a substrate formed by a semiconductor (such as Si) is prepared. The prepared substrate is subjected to oxidation treatment and a silicon oxide film is formed on the substrate. Then, an interlayer insulating film formed by a low dielectric constant (Low-k) film is formed to form through holes at specified intervals. After the through holes are formed, ruthenium is buried in the through holes by thermal CVD to form a ruthenium film. The ruthenium film is etched using the treatment solution of the present invention, thereby suppressing the generation of RuO4 gas and performing flattening. Thus, a ruthenium wiring with high reliability in which RuO2 particles are suppressed can be formed.

[0326] The treatment liquid of the third embodiment of the present invention contains an onium salt.

[0327] (Onium salt)

[0328] The onium salt is used to capture ions containing ruthenium atoms (RuO4 - etc.) and is formed by onium ions and anions.

[0329] Onium ions are compounds of polyatomic cations formed by adding excess protons (hydrogen cations) to monoatomic anions. In addition, onium ions are cations such as imidazolium ions, pyrrolidinium ions, pyridinium ions, piperidinium ions, ammonium ions, phosphonium ions, fluorine ions, chloride ions, bromine ions, iodine ions, oxonium ions, sulfonium ions, selenium ions, tellurium ions, arsonium ions, antimonium ions, and bismuth ions, preferably imidazolium ions, pyrrolidinium ions, pyridinium ions, piperidinium ions, and oxazolium ions.

[0330] Anions are negatively charged ions, and are organic or inorganic anions. There are no particular limitations on organic or inorganic anions, but they are preferably fluoride ions, chloride ions, iodide ions, hydroxide ions, nitrate ions, phosphate ions, sulfate ions, hydrogen sulfate ions, methane sulfate ions, perchlorate ions, chlorate ions, chlorite ions, hypochlorite ions, orthoperiodate ions, metaperiodate ions, iodate ions, iodite ions, hypoiodite ions, acetate ions, carbonate ions, hydrogen carbonate ions, fluoroborate ions, fluorophosphate ions, or trifluoroacetate ions, and more preferably hydroxide ions, chloride ions, or perchlorate ions.

[0331] The above onium salt is represented by the following formula (4).

[0332]

[0333] (In formula (4), Z is an aromatic group or alicyclic group optionally containing nitrogen, sulfur or oxygen atoms, and in the aromatic group or the alicyclic group, carbon or nitrogen optionally has:

[0334] Chlorine, bromine, fluorine, iodine,

[0335] at least one alkyl group having 1 to 15 carbon atoms,

[0336] at least one alkenyloxy group having 2 to 9 carbon atoms,

[0337] at least one aromatic group optionally substituted with an alkyl group having 1 to 15 carbon atoms,

[0338] or, at least one alicyclic group which is optionally substituted with an alkyl group having 1 to 15 carbon atoms.

[0339] A is nitrogen or sulfur.

[0340] R is chlorine, bromine, fluorine, iodine, an alkyl group having 1 to 15 carbon atoms, an allyl group, at least one aromatic group optionally substituted with an alkyl group having 1 to 15 carbon atoms, or at least one alicyclic group optionally substituted with an alkyl group having 1 to 15 carbon atoms.

[0341] X - For organic or inorganic anions.

[0342] n is an integer of 1 or 2, indicating the number of R.

[0343] When n is 2, R may be the same or different and may form a ring.)

[0344] The cation having the above structure can stably exist in an alkaline semiconductor processing liquid. In addition, by forming an aromatic group substituted with an alkyl group or an alkenyl group having a suitable number of carbon atoms, or an alicyclic group substituted with an alkyl group through the carbon or nitrogen of the aromatic group or the alicyclic group of Z in the above formula (4), and by forming an alkyl group, an allyl group, an aromatic group optionally substituted with an alkyl group, or an alicyclic group optionally substituted with an alkyl group through the alkyl group, the allyl group, the aromatic group optionally substituted with an alkyl group, or the alicyclic group optionally substituted with an alkyl group of R in the above formula (4), the solubility of the onium salt containing the cation in the processing liquid and the interaction between the cation and RuO4 can be controlled. - The stability of ion pairs.

[0345] X in the above formula (4) - If it is an organic or inorganic anion, there is no particular limitation, but preferably it is a fluoride ion, a chloride ion, an iodide ion, a hydroxide ion, a nitrate ion, a phosphate ion, a sulfate ion, a hydrogen sulfate ion, a methanesulfate ion, a perchlorate ion, a chlorate ion, a chlorite ion, a hypochlorite ion, an orthoperiodate ion, a metaperiodate ion, an iodate ion, an iodite ion, a hypoiodite ion, an acetate ion, a carbonate ion, a hydrogen carbonate ion, a fluoroborate ion, a fluorophosphate ion or a trifluoroacetate ion, and more preferably a hydroxide ion or a chloride ion.

[0346] In the present invention, if the onium salt represented by formula (4) that can be used preferably is specifically listed, 1,3-dimethylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-methyl-3-n-octylimidazolium chloride, 1,3-di(2,4,6-trimethylphenyl)imidazolium chloride, 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride, 1,3-dicyclohexylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride,

[0043] The following are some of the following: 1-methylpyrrolidinium chloride, 1-ethyl-1-methylpyrrolidinium chloride, 1,1-dimethylpiperidinium chloride, 1-butyl-1-methylpiperidinium chloride, 5-azoniaspiro[4,4]nonane chloride, 1-methylpyridinium chloride, 1-ethylpyridinium chloride, 1-propylpyridinium chloride, 1-fluoropyridinium tetrafluoroborate, 1-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate, 1-fluoro-2,6-dichloropyridinium tetrafluoroborate, N-tert-butyl-5-methylisoxazolium perchlorate, and the like.

[0347] The mechanism by which the treatment liquid of the third embodiment of the present invention suppresses RuO4 gas is considered to be as follows. That is, RuO4 generated by the dissolution of ruthenium - The trapped RuO4 - It exists relatively stably in the treatment liquid in the form of ion pairs, so it is not easy to change into RuO4. As a result, the generation of RuO4 gas is suppressed and the generation of RuO2 particles is also suppressed.

[0348] In addition, the concentration of the onium salt in the treatment solution of the third embodiment of the present invention is preferably 0.0001 to 50% by mass. If the amount of onium salt added is too small, not only will RuO4 - The interaction between the RuO4 and the like is weakened, the RuO4 gas suppression effect is reduced, and the RuO4 that can be dissolved in the treatment solution - The amount of etc. is reduced, so the number of reuses of the treatment solution is reduced. On the other hand, if the addition amount is too much, the adsorption amount of the onium salt on the ruthenium surface increases, which becomes the reason for the reduction of the ruthenium dissolution rate and the uneven etching of the ruthenium surface. Therefore, the treatment solution of the third embodiment of the present invention preferably contains 0.0001 to 50 mass % of the onium salt, more preferably contains 0.01 to 35 mass %, and further preferably contains 0.1 to 20 mass %. It should be noted that when adding an onium salt, only one or a combination of two or more can be added. Even if it contains more than two onium salts, if the total concentration of the onium salt is within the above concentration range, the generation of RuO4 gas can be effectively suppressed.

[0349] (Oxidant)

[0350] The treatment liquid of the third aspect of the present invention may contain an oxidant. As the oxidant, for example, halogen oxygen-containing acids, permanganic acid and their salts, hydrogen peroxide, ozone, cerium (IV) salts, etc. can be listed, but are not limited to them. Here, halogen oxygen-containing acid refers to hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypoiodous acid, iodous acid, iodic acid, metaperiodic acid, orthoperiodic acid or their ions. By containing an oxidant, the dissolution of ruthenium is promoted, and the redissolution of the precipitated RuO2 particles is promoted. Therefore, the treatment liquid containing onium salts and oxidants can suppress the generation of RuO4 gas and RuO2 particles, and effectively process the wafer containing Ru. Among the above-mentioned oxidants, from the viewpoint of being alkaline and stable to use, and being able to widely select the concentration range, halogen oxygen-containing acids and their ions, or hydrogen peroxide are suitable as oxidants, more preferably hypochlorous acid, metaperiodic acid, orthoperiodic acid and their ions, and most preferably hypochlorous acid and hypochlorite ions. Furthermore, these oxidizing agents may be present in the treatment liquid in the form of a salt. As the salt, for example, tetraalkylammonium hypochlorite is preferred, and tetramethylammonium hypochlorite is more preferred.

[0351] When the treatment liquid of the third embodiment of the present invention is a treatment liquid containing hypochlorite ions, the concentration of the hypochlorite ions is preferably in the range of 0.05 to 20.0% by mass relative to the total treatment liquid. If it is within the above range, the decomposition reaction of the hypochlorite ions in the treatment liquid is suppressed, and the concentration of the hypochlorite ions is suppressed from decreasing, and the treatment liquid can be treated with Therefore, the concentration of hypochlorite ions is preferably in the range of 0.1 to 15% by mass, more preferably 0.3 to 10% by mass, further preferably 0.5 to 6% by mass, and particularly preferably 0.5 to 4% by mass.

[0352] In the treatment solution of the third embodiment of the present invention, the residual part other than the onium salt, the organic solvent described in detail below and other additives is water. The water contained in the treatment solution of the present invention 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 pure water and ultrapure water are particularly preferred. This water can be obtained by a known method widely used in semiconductor manufacturing.

[0353] (Organic Solvent)

[0354] As described above, in the third embodiment of the present invention, RuO4 generated when ruthenium is dissolved - The RuO4 gas is retained in the treatment solution by the electrostatic interaction with the onium ions, thereby suppressing the generation of RuO4 gas. - The isocyanate ions are dissolved in the solution in the form of ion pairs, but when the solubility is exceeded, a precipitate is formed. The precipitate is the main cause of particles in the semiconductor formation process, thus resulting in a reduction in yield. Therefore, it is important not to produce a precipitate, and it is preferred to increase the solubility of the ion pair. As this method, adding an organic solvent is effective.

[0355] Generally, the lower the relative dielectric constant of the solvent, the easier it is to dissolve electrically neutral chemical species. When the relative dielectric constant of the solvent is low, electrically neutral ion pairs are also easily dissolved. Therefore, in order to increase the solubility of ion pairs, it is preferred to add an organic solvent having a lower relative dielectric constant than water (relative dielectric constant 78) as the organic solvent added to the treatment liquid of the present invention. In this way, the relative dielectric constant of the treatment liquid can be lowered compared to the case of only water, and the onium ion and RuO4 can be increased. - The solubility of ion pairs such as RuO4 can effectively suppress the generation of RuO4 gas. As the added organic solvent, any organic solvent can be used as long as it has a relative dielectric constant lower than that of water, but the relative dielectric constant is preferably 45 or less, more preferably 20 or less, and further preferably 10 or less. It should be noted that these relative dielectric constants are values ​​at 25°C.

[0356] Specific examples of such organic solvents include sulfolane (relative dielectric constant 43), acetonitrile (relative dielectric constant 37), carbon tetrachloride (relative dielectric constant 2.2), and 1,4-dioxane (relative dielectric constant 2.2), but the organic solvent is of course not limited to these.

[0357] When an organic solvent with a low relative dielectric constant is added, it may not be easily mixed with water. However, even in this case, the solubility of the ion pair can be increased by using an organic solvent that is slightly soluble in water, and the addition of an organic solvent is effective in suppressing the generation of RuO4 gas.

[0358] When the treatment liquid contains an oxidant, in order to prevent the organic solvent from being decomposed by the oxidant, it is preferred that the two do not react, but any organic solvent can be used if the reactivity with the oxidant is low. If an example is given, when the oxidant is a hypochlorite ion, sulfolanes, alkyl nitriles, halogenated alkanes, ethers, etc. have low reactivity with hypochlorite ions, and therefore, can be suitably used as organic solvents added to the treatment liquid. If such organic solvents are specifically listed, they are sulfolanes, acetonitrile, carbon tetrachloride, 1,4-dioxane, etc., but of course the organic solvent is not limited to them.

[0359] The organic solvent can be added in an amount required to suppress the formation of precipitates. Therefore, the concentration of the organic solvent in the treatment solution can be 0.1 mass % or more, but in order to increase the amount of ion pairs dissolved, RuO4 - The organic solvent is stably maintained in the solution in the form of ion pairs, and the concentration of the organic solvent is preferably 1% by mass or more. In addition, if it is within the range that does not damage the solubility of ruthenium and the storage stability of the treatment solution, the more the amount of organic solvent added, the more the amount of ion pairs that can be dissolved in the treatment solution increases, so not only can the generation of precipitates be suppressed, but also the RuO4 gas suppression effect will not decrease even if the organic solvent evaporates in small amounts, and the generation of RuO4 gas can be suppressed even when the treatment solution is reused, etc., which has many advantages. Furthermore, the added organic solvent can be added in one or a combination of multiple types.

[0360] If a highly volatile solvent is used as the organic solvent, the organic solvent in the processing solution evaporates during the processing of the semiconductor wafer, so the concentration of the organic solvent changes and the relative dielectric constant of the processing solution changes, making it difficult to perform stable processing. In addition, from the viewpoint of storage stability, it is also preferred that the volatility of the organic solvent is low. Specifically, an organic solvent having a vapor pressure of 50 mmHg or less at 20°C is preferred, and an organic solvent having a vapor pressure of 20 mmHg or less is more preferred.

[0361] The treatment liquid of the third embodiment of the present invention preferably has a pH of 7 or more and 14 or less at 25°C. When the pH of the treatment liquid is less than 7, the dissolution of ruthenium occurs via RuO2 and Ru(OH)3, rather than via RuO4. - Therefore, the effect of adding cations is reduced. Furthermore, when the pH is less than 7, RuO2 particles are easily generated, and the problem of increased generation of RuO4 gas also occurs. Therefore, in order for the third-form treatment liquid of the present invention to fully exert its ability to inhibit the generation of RuO4 gas, the pH of the treatment liquid is preferably 7 to 14, more preferably 9 to 13. If it is within this pH range, the ruthenium dissolved in the treatment liquid is RuO4 - or RuO4 2- It exists in the form of anions, so it is easy to form ion pairs with the onium ions contained in the treatment solution of the present invention, and can effectively inhibit the generation of RuО4 gas.

[0362] (Other additives)

[0363] The treatment liquid of the third embodiment of the present invention may be mixed with other additives that have been used in semiconductor treatment liquids as needed within the scope that does not impair the purpose of the present invention. For example, as other additives, acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidants, reducing agents, complexing agents, chelating agents, surfactants, defoaming agents, pH adjusters, stabilizers, etc. may be added. These additives may be added alone or in combination.

[0364] The treatment liquid of the third embodiment of the present invention may contain alkali metal ions, alkaline earth metal ions, etc., due to these additives or due to reasons in the manufacture of the treatment liquid. For example, sodium ions, potassium ions, calcium ions, etc. may be contained. However, when these alkali metal ions and alkaline earth metal ions remain on the semiconductor wafer, they have an adverse effect on the semiconductor element (adverse effects such as reduced yield of semiconductor wafers), so the amount is preferably small, and it is actually appropriate to contain no ions indefinitely. Therefore, for example, as a pH adjuster, organic bases such as ammonia, amines, choline or tetraalkylammonium hydroxide are preferred, rather than alkali metal hydroxides such as sodium hydroxide and alkaline earth metal hydroxides.

[0365] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1 mass % or less, more preferably 0.7 mass % or less, further preferably 0.3 mass % or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0366] (Treatment liquid of the fourth aspect)

[0367] Next, the processing liquid and the like according to the fourth aspect of the present invention will be described.

[0368] The processing liquid of the fourth embodiment of the present invention is a processing liquid that can process a semiconductor wafer containing ruthenium without generating RuO4 gas. Therefore, the processing liquid of the fourth embodiment of the present invention is a processing liquid that can be suitably used in an etching process, a residue removal process, a washing process, a CMP process, etc. in a semiconductor manufacturing process.

[0369] The ruthenium contained in the semiconductor wafer to which the treatment liquid of the fourth mode of the present invention is applicable can be formed by any method. The film formation of ruthenium can utilize methods widely known in the semiconductor manufacturing process, such as CVD, ALD, sputtering, plating, etc. These rutheniums can be metallic ruthenium, or ruthenium oxides, alloys with other metals, intermetallic compounds, ionic compounds, and complexes. In addition, ruthenium can be exposed on the surface of the wafer, or covered by other metals, metal oxide films, insulating films, resists, etc. Even when covered by other materials, when ruthenium contacts the treatment liquid and dissolution of ruthenium occurs, the onium salt contained in the treatment liquid of the fourth mode of the present invention can also exert the inhibitory effect of RuO4 gas generation. Furthermore, even when the treatment liquid of the fourth mode of the present invention does not actively dissolve ruthenium, that is, when ruthenium is the object of protection during processing, the RuO4 gas generated by the very little ruthenium dissolved can be suppressed.

[0370] For example, in the ruthenium wiring formation process, when the processing liquid of the fourth mode of the present invention is used, a ruthenium wiring with high reliability in which RuO2 particles are suppressed can be formed through the same steps and operations as those using the processing liquid of the second mode of the present invention.

[0371] The processing liquid of the fourth aspect of the present invention contains an onium salt formed of an onium ion and an anion.

[0372] The above onium salt is represented by the following formula (5).

[0373]

[0374] (In formula (5), A + are independently ammonium ions or phosphonium ions, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 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. At least one hydrogen in the ring of the aryl group and the aryl group in the aralkyl group may be substituted 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 at least one hydrogen in these groups may be substituted with fluorine or chlorine. In formula (5), X -is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion, and a is an integer of 1 to 10. )

[0375] If R in the above formula (5) 1 , R 2 , R 3 , R 4 , R 5 , R 6 The alkyl groups independently have carbon numbers of 1 to 25 and can be used without particular limitation. - On the other hand, the larger the carbon number, the more bulky the onium ions are, so the RuO4 gas is easily suppressed. - The more electrostatic interactions are generated, the less ion pairs are dissolved in the treatment solution, and a precipitate is generated. The precipitate forms particles and causes a decrease in the yield of semiconductor components. In addition, the greater the carbon number, the lower the solubility in the treatment solution, and the easier it is to generate bubbles in the treatment solution. On the contrary, if the carbon number is small, the onium ions and RuO4 - The interaction of the RuO4 gas is weakened, so the RuO4 gas suppression effect is weakened. Therefore, the carbon number of the alkyl group in formula (5) is preferably independently 1 to 25, more preferably 2 to 10, and most preferably 3 to 6. If it is an onium salt of an alkyl group having such a carbon number, it can be reacted with RuO4 - The interaction of the above mentioned substances can suppress the generation of RuO4 gas and makes it difficult to generate precipitates, so it can be suitably used as a semiconductor processing liquid.

[0376] In the above formula (5), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 The aryl group independently includes not only aromatic hydrocarbons but also heteroaryl groups containing hetero atoms, and although not particularly limited, is preferably a phenyl group or a naphthyl group.

[0377] In the above formula (5), X -If it is an anion, there is no particular limitation, but preferably it is a fluoride ion, a chloride ion, an iodide ion, a hydroxide ion, a nitrate ion, a phosphate ion, a sulfate ion, a hydrogen sulfate ion, a methanesulfate ion, a perchlorate ion, a chlorate ion, a chlorite ion, a hypochlorite ion, an orthoperiodate ion, a metaperiodate ion, an iodate ion, an iodite ion, a hypoiodite ion, an acetate ion, a carbonate ion, a hydrogen carbonate ion, a fluoroborate ion, or a trifluoroacetate ion.

[0378] The mechanism by which the treatment liquid of the fourth aspect of the present invention suppresses RuO4 gas is considered to be as follows. That is, RuO4 generated by the dissolution of ruthenium - The trapped RuO4 - It exists relatively stably in the treatment liquid in the form of ion pairs, so it is not easy to change into RuO4. As a result, the generation of RuO4 gas is suppressed and the generation of RuO2 particles is also suppressed.

[0379] The onium salt shown in the above formula (5) is a salt formed by ammonium ions or phosphonium ions that can stably exist in the treatment solution, i.e., an ammonium salt or a phosphonium salt. Usually, the alkyl chain length of the ammonium ion or the phosphonium ion can be easily controlled, and then it is also easy to introduce allyl groups and aryl groups. Thus, the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surface activity performance, etc. of the ammonium ion or the phosphonium ion can be controlled, and the ammonium salt or the phosphonium salt containing the ion can also control its size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, surface activity performance, etc.

[0380] The onium salt represented by the above formula (5) contained in the treatment liquid of the fourth aspect of the present invention is preferably an ammonium salt because of its high stability, easy industrial availability of a high-purity product, and low cost.

[0381] The onium salt represented by the above formula (5) is preferably a hexamethylammonium salt or a decamethylammonium salt which is particularly excellent in stability and can be easily synthesized. The hexamethylammonium salt or the decamethylammonium salt is more preferably a hydroxide or a halide.

[0382] In the fourth aspect of the present invention, as the onium salt that can be suitably used, methylammonium salts selected from hexamethylammonium chloride and decamethonium iodide can be listed. Furthermore, these salts are more preferably hydroxides or halides. The processing liquid containing these onium salts can suppress RuO4 gas, especially in the processing of semiconductor wafers, and can be processed without the generation of RuO2 particles.

[0383] In addition, the concentration of the onium salt in the treatment solution of the fourth embodiment of the present invention is preferably 0.0001 to 50% by mass. If the amount of onium salt added is too small, not only RuO4 -The interaction between the RuO4 and the like is weakened, the RuO4 gas suppression effect is reduced, and the RuO4 that can be dissolved in the treatment solution - The amount of etc. is reduced, so the number of reuses of the treatment solution is reduced. On the other hand, if the addition amount is too much, the adsorption amount of the onium salt on the ruthenium surface increases, which becomes the cause of the reduced ruthenium dissolution rate and the uneven etching of the ruthenium surface. Therefore, the treatment solution of the fourth embodiment of the present invention preferably contains 0.0001 to 50% by mass of onium salt, more preferably 0.01 to 40% by mass, and further preferably 0.1 to 30% by mass. It should be noted that when adding an onium salt, only one or a combination of two or more can be added. Even if it contains more than two onium salts, if the total concentration of the onium salt is within the above concentration range, the generation of RuO4 gas can be effectively suppressed.

[0384] (Oxidant)

[0385] The treatment liquid of the fourth mode of the present invention may contain an oxidant. As the oxidant, for example, halogen oxygen-containing acids, permanganic acid and their salts, hydrogen peroxide, ozone, cerium (IV) salts, etc. can be listed, but are not limited to them. Here, halogen oxygen-containing acid refers to hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypoiodous acid, iodous acid, iodic acid, metaperiodic acid, orthoperiodic acid or their ions. By containing an oxidant, the dissolution of ruthenium is promoted, and the redissolution of the precipitated RuO2 particles is promoted. Therefore, the treatment liquid containing onium salts and oxidants can suppress the generation of RuO4 gas and RuO2 particles, and effectively process wafers containing Ru. Among the above-mentioned oxidants, from the viewpoint of being alkaline and stable to use, and being able to widely select the concentration range, halogen oxygen-containing acids and their ions, or hydrogen peroxide are suitable as oxidants, more preferably hypochlorous acid, metaperiodic acid, orthoperiodic acid and their ions, and most preferably hypochlorous acid and hypochlorite ions.

[0386] In the case where the treatment liquid of the fourth aspect of the present invention is a treatment liquid containing hypochlorite ions, the concentration of the hypochlorite ions is preferably in the range of 0.05 to 20.0% by mass relative to the entire treatment liquid. If it is within the above range, the decomposition reaction of the hypochlorite ions in the treatment liquid is suppressed, and the concentration of the hypochlorite ions is suppressed from decreasing, and the treatment liquid can be treated with Therefore, the concentration of hypochlorite ions is preferably in the range of 0.1 to 15% by mass, more preferably 0.3 to 10% by mass, further preferably 0.5 to 6% by mass, and particularly preferably 0.5 to 4% by mass.

[0387] In the treatment solution of the fourth embodiment of the present invention, the residual part except the onium salt, the organic solvent described in detail below and other additives is water. The water contained in the treatment solution of the fourth embodiment of the present invention is preferably water from which metal ions, organic impurities, particles, etc. are removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and pure water and ultrapure water are particularly preferred. This water can be obtained by a known method widely used in semiconductor manufacturing.

[0388] (Organic Solvent)

[0389] As described above, in the fourth embodiment of the present invention, RuO4 generated when ruthenium is dissolved - The RuO4 gas is retained in the treatment solution by the electrostatic interaction with the onium ions, thereby suppressing the generation of RuO4 gas. - The isocyanate ions are dissolved in the solution in the form of ion pairs, but when the solubility is exceeded, a precipitate is formed. The precipitate is the main cause of particles in the semiconductor formation process, thus resulting in a reduction in yield. Therefore, it is important not to produce a precipitate, and it is preferred to increase the solubility of the ion pair. As this method, adding an organic solvent is effective.

[0390] Generally, the lower the relative dielectric constant of the solvent, the easier it is to dissolve electrically neutral chemical species. When the relative dielectric constant of the solvent is low, electrically neutral ion pairs are also easily dissolved. Therefore, in order to increase the solubility of ion pairs, it is preferred to add an organic solvent having a lower relative dielectric constant than water (relative dielectric constant 78) as the organic solvent added to the treatment liquid of the fourth embodiment of the present invention. In this way, the relative dielectric constant of the treatment liquid can be lowered compared to the case of only water, and the onium ion and RuO4 can be increased. - The solubility of ion pairs such as RuO4 can effectively suppress the generation of RuO4 gas. As the added organic solvent, any organic solvent can be used as long as it has a relative dielectric constant lower than that of water, but the relative dielectric constant is preferably 45 or less, more preferably 20 or less, and further preferably 10 or less. It should be noted that these relative dielectric constants are values ​​at 25°C.

[0391] Specific examples of such organic solvents include sulfolane (relative dielectric constant 43), acetonitrile (relative dielectric constant 37), carbon tetrachloride (relative dielectric constant 2.2), and 1,4-dioxane (relative dielectric constant 2.2), but the organic solvent is of course not limited to these.

[0392] When an organic solvent with a low relative dielectric constant is added, it may not be easily mixed with water. However, even in this case, the solubility of the ion pair can be increased by using an organic solvent that is slightly soluble in water, and the addition of an organic solvent is effective in suppressing the generation of RuO4 gas.

[0393] When the treatment liquid contains an oxidant, in order to prevent the organic solvent from being decomposed by the oxidant, it is preferred that the two do not react, but any organic solvent can be used if the reactivity with the oxidant is low. If an example is given, when the oxidant is a hypochlorite ion, sulfolane, alkyl nitriles, halogenated alkanes, ethers, etc. have low reactivity with hypochlorite ions, and therefore, can be suitably used as an organic solvent added to the treatment liquid of the fourth embodiment of the present invention. If such an organic solvent is specifically listed, it is sulfolane, acetonitrile, carbon tetrachloride, 1,4-dioxane, etc., but of course the organic solvent is not limited to them.

[0394] The organic solvent can be added in an amount required to suppress the formation of precipitates. Therefore, the concentration of the organic solvent in the treatment liquid of the fourth embodiment of the present invention can be 0.1 mass % or more, but in order to increase the amount of ion pairs dissolved, RuO4 - The organic solvent is stably maintained in the solution in the form of ion pairs, and the concentration of the organic solvent is preferably 1% by mass or more. In addition, if it is within the range that does not damage the solubility of ruthenium and the storage stability of the treatment solution, the more the amount of organic solvent added, the more the amount of ion pairs that can be dissolved in the treatment solution increases, so not only can the generation of precipitates be suppressed, but also the RuO4 gas suppression effect will not decrease even if the organic solvent evaporates in small amounts, and the generation of RuO4 gas can be suppressed even when the treatment solution is reused, etc., which has many advantages. Furthermore, the added organic solvent can be added in one or a combination of multiple types.

[0395] If a highly volatile solvent is used as the organic solvent, the organic solvent in the processing solution evaporates during the processing of the semiconductor wafer, so the concentration of the organic solvent changes and the relative dielectric constant of the processing solution changes, making it difficult to perform stable processing. In addition, from the viewpoint of storage stability, it is also preferred that the volatility of the organic solvent is low. Specifically, an organic solvent having a vapor pressure of 50 mmHg or less at 20°C is preferred, and an organic solvent having a vapor pressure of 20 mmHg or less is more preferred.

[0396] The treatment liquid of the fourth embodiment of the present invention preferably has a pH of 7 or more and 14 or less at 25°C. When the pH of the treatment liquid is less than 7, the dissolution of ruthenium occurs via RuO2 and Ru(OH)3, rather than via RuO4. - Therefore, the effect of adding cations is reduced. Furthermore, when the pH is less than 7, RuO2 particles are easily generated, and the problem of increased generation of RuO4 gas also occurs. Therefore, in order for the fourth method of the treatment liquid of the present invention to fully exert the ability to inhibit the generation of RuO4 gas, the pH of the treatment liquid is preferably 7 or more and 14 or less, more preferably 9 or more and 13 or less. If it is within this pH range, the ruthenium dissolved in the treatment liquid is RuO4 - or RuO4 2-It exists in the form of anions, so it is easy to form ion pairs with the onium ions contained in the treatment liquid of the fourth embodiment of the present invention, and can effectively suppress the generation of RuО4 gas.

[0397] (Other additives)

[0398] The treatment liquid of the fourth embodiment of the present invention may be mixed with other additives that have been used in semiconductor treatment liquids as needed within the scope that does not impair the purpose of the present invention. For example, as other additives, acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidants, reducing agents, complexing agents, chelating agents, surfactants, defoaming agents, pH adjusters, stabilizers, etc. may be added. These additives may be added alone or in combination.

[0399] The fourth embodiment of the present invention may contain alkali metal ions, alkaline earth metal ions, etc., due to these additives or due to reasons for the manufacture of the treatment liquid. For example, sodium ions, potassium ions, calcium ions, etc. may be contained in the treatment liquid. However, when these alkali metal ions and alkaline earth metal ions remain on the semiconductor wafer, they have an adverse effect on the semiconductor element (adverse effects such as reduced yield of semiconductor wafers), so the amount is preferably small, and it is actually appropriate to contain no ions indefinitely. Therefore, for example, as a pH adjuster, organic bases such as ammonia, amines, choline or tetraalkylammonium hydroxide are preferred, rather than alkali metal hydroxides such as sodium hydroxide and alkaline earth metal hydroxides.

[0400] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1 mass % or less, more preferably 0.7 mass % or less, further preferably 0.3 mass % or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less.

[0401] (Ruthenium-containing gas generation inhibitor)

[0402] The inhibitor for the generation of ruthenium-containing gas is added to a liquid for treating ruthenium to suppress the generation of ruthenium-containing gas, and refers to a liquid containing an onium salt represented by the above formulas (2) to (5).

[0403] The liquid for treating ruthenium can be any liquid if it contains a component that contacts ruthenium and provides physical and chemical changes to the ruthenium, and an example thereof is a solution containing an oxidant. As the oxidant, the oxidants exemplified in the description of the treatment liquid of the second mode, the treatment liquid of the third mode, and the treatment liquid of the fourth mode of the present invention can be listed. For ruthenium treated by the liquid for treating ruthenium, all or part of it is dissolved, dispersed or precipitated in the treatment liquid, which becomes the cause of the generation of RuO4 (gas) and / or RuO2 (particles).

[0404] In a liquid for treating ruthenium and a liquid containing a ruthenium-containing gas generation inhibitor of the present invention (also described as a treatment liquid containing a gas generation inhibitor), RuO4 present in the treatment liquid - etc. form ion pairs dissolved in the treatment solution with onium ions, thereby inhibiting the formation of RuO4 - This is because the generation of RuO4 (gas) from RuO4 (solution) is greatly reduced, and the generation of RuO2 (particles) from RuO4 (gas) is suppressed.

[0405] As described above, the second processing liquid, the third processing liquid, and the fourth processing liquid of the present invention contain any one of the onium salts shown in the above formulas (2) to (5), and are therefore processing liquids that can process semiconductor wafers containing ruthenium without generating RuO4 gas. That is, the second processing liquid, the third processing liquid, and the fourth processing liquid of the present invention are liquids for processing ruthenium and are also generation inhibitors of gases containing ruthenium. Therefore, the processing liquids of these methods can also be used as generation inhibitors of gases containing ruthenium.

[0406] For conditions such as the type and content of any onium salt represented by the above formulas (2) to (5) in the ruthenium-containing gas generation inhibitor, other components and their contents, and the pH of the ruthenium-containing gas generation inhibitor, the same conditions as those described in the instructions for the semiconductor wafer processing liquid of each method can be applied.

[0407] In addition, in addition to these conditions, for example, as the content of any one of the onium salts shown in the above formulas (2) to (5) in the generation inhibitor of ruthenium-containing gas, 0.0001 to 50 mass %, more preferably 0.01 to 35 mass %, and further preferably 0.1 to 20 mass % can be listed. As described later, the concentration can be adjusted in a manner such that the concentration of the onium salt in the mixed solution when mixed with the liquid that is the object of suppressing the generation of ruthenium-containing gas, that is, the liquid for treating ruthenium, forms a prescribed amount. In addition, the same pH adjuster as the pH adjuster shown in the second to fourth modes described above can be appropriately added to the generation inhibitor of ruthenium-containing gas. For the content of the pH adjuster, as described later, it can be adjusted in a manner such that the pH of the mixed solution when mixed with the liquid for treating ruthenium forms a prescribed range. For example, as the content of the pH adjuster in the generation inhibitor of ruthenium-containing gas, if it is an effective amount, specifically, 0.000001 to 10 mass % can be illustrated.

[0408] (Method for suppressing generation of gas containing ruthenium)

[0409] A method for suppressing the generation of ruthenium-containing gas is a method for suppressing the generation of ruthenium-containing gas, which includes adding the above-mentioned ruthenium-containing gas generation inhibitor to a process for treating ruthenium liquid. Specifically, for example, the generation inhibitor of ruthenium-containing gas of the present invention is added to the liquid (liquid for treating ruthenium) used in the process of treating ruthenium such as etching process, residue removal process, washing process, CMP process in the semiconductor manufacturing process, thereby suppressing the generation of ruthenium-containing gas. In addition, in each device used in these semiconductor manufacturing processes, when washing ruthenium attached to the inner wall of the chamber, piping, etc., the generation of ruthenium-containing gas can also be suppressed by using the generation inhibitor of ruthenium-containing gas. For example, in the maintenance of a device that forms Ru using physical vapor deposition (PVD) or chemical vapor deposition (CVD), by adding the generation inhibitor of ruthenium-containing gas of the present invention to the washing liquid used to remove Ru attached to the chamber, piping, etc., the generation of ruthenium-containing gas during washing can be suppressed. According to this method, the generation of ruthenium-containing gas can be suppressed by the mechanism described in the above description of the generation inhibitor of ruthenium-containing gas.

[0410] It should be noted that in the method for inhibiting the generation of ruthenium-containing gas, it is preferred to adjust the concentration of the onium salt in the generation inhibitor of ruthenium-containing gas and its addition amount in a mixed solution of the generation inhibitor of ruthenium-containing gas and the liquid for treating ruthenium so that the concentration of one or more onium salts represented by any one of the above formulas (2) to (5) forms 0.0001 to 50% by mass. In addition, in the method for inhibiting the generation of ruthenium-containing gas, a pH adjuster the same as the pH adjuster shown in the second to fourth methods described above can be appropriately added to the generation inhibitor of ruthenium-containing gas. The content of the pH adjuster in the generation inhibitor of ruthenium-containing gas and the addition amount of the generation inhibitor of ruthenium-containing gas can be appropriately adjusted in a manner such that the pH of the mixed solution when mixed with the liquid for treating ruthenium forms, for example, 7 to 14.

[0411] The amount of the inhibitor of the generation of the gas containing ruthenium added to the liquid for treating ruthenium depends on the amount of ruthenium dissolved in the treatment liquid containing the inhibitor of the generation of the gas. There is no particular limitation on the amount of the inhibitor of the generation of the gas containing ruthenium added. For example, when the amount of ruthenium dissolved in the liquid for treating ruthenium is 1, the amount of the inhibitor of the generation of the gas containing ruthenium is preferably 10 to 500,000, more preferably 100 to 100,000, and further preferably 1,000 to 50,000 by weight.

[0412] (Treatment agent for waste liquid containing ruthenium)

[0413] The treatment agent for waste liquid containing ruthenium is a liquid containing an onium salt represented by the above formula (2) to (5) that is added to the waste liquid containing ruthenium to suppress the generation of ruthenium-containing gas. Thus, the treatment liquid (the treatment liquid of the second mode, the treatment liquid of the third mode, and the treatment liquid of the fourth mode) containing the onium salt represented by the above formula (2), (3), (4), or (5) can also be used as a treatment agent for waste liquid containing ruthenium by utilizing the effect of suppressing the generation of ruthenium-containing gas.

[0414] Here, the waste liquid containing ruthenium refers to a solution containing Ru even in a small amount. Here, Ru is not limited to ruthenium metal, and any ruthenium element can be contained, such as Ru, RuO4 - 、RuO4 2- , RuO4, RuO2, etc. Examples of the liquid include a liquid obtained by etching a semiconductor wafer containing ruthenium using an etching liquid having a composition different from that of the various embodiments of the present invention, and a liquid obtained by treating a semiconductor wafer using a treatment liquid of the various embodiments of the present invention. In addition, not limited to etching of semiconductor wafers, a ruthenium-containing liquid produced by a semiconductor manufacturing process, chamber cleaning, etc. as described in the above-mentioned method for inhibiting the generation of ruthenium-containing gas is also an example.

[0415] When the waste liquid contains Ru even in a trace amount, RuO2 particles are generated through RuO4 gas, which may contaminate the tank and piping, or promote the degradation of the device due to the oxidation of the particles. In addition, the RuO4 gas generated from the waste liquid is highly toxic to the human body even at a low concentration. In this way, the waste liquid containing ruthenium has various adverse effects on the device or the human body, so emergency treatment is required to suppress the generation of RuO4 gas.

[0416] In the treatment agent for ruthenium-containing waste liquid of the present invention, the same conditions as those described in the description of the processing liquid for semiconductor wafers of each method can be applied to the type and content of any one of the onium salts represented by the above formulas (2) to (5), other components and their contents, pH and other conditions.

[0417] In addition, in addition to these conditions, for example, as the content of any one of the onium salts shown in the above-mentioned formulas (2) to (5) in the treatment agent for the waste liquid containing ruthenium, 0.0001 to 50% by mass, more preferably 0.01 to 35% by mass, can be listed. This concentration can be adjusted in a manner such that the concentration of the above-mentioned onium salt in the mixed solution when mixed with the waste liquid containing ruthenium forms a prescribed amount, as described later. In addition, the same pH adjusting agent as the pH adjusting agent shown in the second to fourth modes described above can be appropriately added to the treatment agent for the waste liquid containing ruthenium. For the content of the pH adjusting agent, as described later, the pH of the mixed solution when mixed with the waste liquid containing ruthenium can be adjusted in a manner such that a prescribed range is formed. For example, as the content of the pH adjusting agent in the treatment agent for the waste liquid containing ruthenium, if it is an effective amount, specifically 0.000001 to 10% by mass can be illustrated.

[0418] (Method for treating waste liquid containing ruthenium)

[0419] The method for treating waste liquid containing ruthenium of the present invention is a method for treating waste liquid containing ruthenium, comprising adding the treating agent of the waste liquid containing ruthenium to the process of the waste liquid containing ruthenium described later. According to the method, the ruthenium-containing gas produced by the waste liquid containing ruthenium can be suppressed by the mechanism shown in the description of the generation inhibitor of the gas containing ruthenium. Therefore, not only the treatment of the waste liquid containing ruthenium becomes easy, but also the exhaust equipment and removal equipment can be simplified, and the cost of treating the gas containing ruthenium can be reduced. Furthermore, the danger of the operator being exposed to the highly toxic gas containing ruthenium is reduced, and the safety is greatly improved.

[0420] It should be noted that in the treatment method of the waste liquid containing ruthenium, it is preferred that the concentration of the onium salt in the treatment agent for the waste liquid containing ruthenium and the mixed solution of the waste liquid containing ruthenium is adjusted in a manner such that the concentration of one or more of the onium salts shown in any one of the above-mentioned formulas (2) to (5) is formed in the treatment agent for the waste liquid containing ruthenium and the mixed solution containing the waste liquid containing ruthenium is, for example, 0.0001 to 50% by mass. In addition, in the treatment method of the waste liquid containing ruthenium, a pH adjusting agent identical to the pH adjusting agent shown in the above-mentioned second to fourth modes can be appropriately added to the treatment agent for the waste liquid containing ruthenium. The content of the pH adjusting agent in the treatment agent for the waste liquid containing ruthenium and the addition amount of the treatment agent for the waste liquid containing ruthenium can be appropriately adjusted in a manner such that the pH of the mixed solution when mixed with the waste liquid containing ruthenium is formed in a range of, for example, 7 to 14.

[0421] The amount of the treatment agent for the waste liquid containing ruthenium to be added relative to the waste liquid containing ruthenium depends on the amount of ruthenium in the waste liquid containing ruthenium. There is no particular restriction on the amount of the treatment agent for the waste liquid containing ruthenium. For example, when the amount of ruthenium in the waste liquid containing ruthenium is set to 1, the weight ratio is preferably 10 to 500,000, more preferably 100 to 100,000, and further preferably 1,000 to 50,000.

[0422] Example

[0423] The present invention is described in more detail below through experimental examples, but the present invention is not limited to these experimental examples.

[0424] <Experimental Example 1 and Reference Example 1>

[0425] (pH measurement method)

[0426] The pH of 30 mL of the treatment liquid prepared in Experimental Example 1 and Reference Example 1 was measured using a tabletop pH meter (LAQUAF-73, manufactured by Horiba, Ltd.) The pH measurement was performed after the temperature of the treatment liquid was stabilized at 25°C.

[0427] (Calculation method of effective chlorine concentration and hypochlorite ion concentration)

[0428] After preparing the treatment liquid of the experimental example and the reference example, add 0.5 mL of the treatment liquid and 2 g of potassium iodide (manufactured by Wako Pure Chemical Industries, Ltd., special reagent grade), 8 mL of 10% acetic acid, and 10 mL of ultrapure water to a 100 mL conical flask, and stir until the solid is dissolved to obtain a brown solution. For the manufactured brown solution, use 0.02M sodium thiosulfate solution (manufactured by Wako Pure Chemical Industries, Ltd., for volumetric analysis) to perform redox titration until the color of the solution changes from brown to very light yellow, and then add starch solution to obtain a lavender solution. Further add 0.02M sodium thiosulfate solution to the solution, and take the point where it becomes colorless and transparent as the end point to calculate the effective chlorine concentration. In addition, the hypochlorite ion concentration is calculated from the obtained effective chlorine concentration. For example, if the effective chlorine concentration is 1%, the hypochlorite ion concentration is 0.73%. This is common to the following experimental examples 1 to 5.

[0429] (Calculation method of tetramethylammonium ion concentration)

[0430] The tetramethylammonium ion concentration in the treatment liquid of the experimental example and the reference example was calculated from the pH, hypochlorite ion concentration, and sodium ion concentration. It should be noted that the sodium ion concentration was measured by ICP-MS (inductively coupled plasma mass spectrometry).

[0431] (Calculation method of ruthenium etching rate)

[0432] An oxide film is formed on a silicon wafer using a batch thermal oxidation furnace, and ruthenium is sputtered on it. The sheet resistance was measured with a four-probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted into film thickness.

[0433] 30 mL of the treatment solution of each experimental example and reference example was prepared in a fluororesin container with a lid (manufactured by AsOne, PFA container 94.0 mL), and each sample piece of 10×20 mm was immersed in the treatment solution at 23°C for 1 minute. The value obtained by dividing the change in film thickness before and after treatment by the immersion time was calculated as the etching rate.

[0434] In addition, the etching rate is calculated based on The etching time of ruthenium is After the treatment for a period of time, the ruthenium surface was observed using a field emission scanning electron microscope (FE-SEM; Field Emission Scanning Electron Microscope) at 100,000 times. The case where surface roughness was observed at this time was rated as bad (C), the case where slightly rough surface was observed was rated as good (B), and the case where no surface roughness was observed was rated as excellent (A).

[0435] <Experimental Example 1-1>

[0436] (Preparation of Samples to be Etched)

[0437] A silicon wafer with a cleaned surface was prepared, and a thermal oxide film of 500 nm was formed. Ruthenium was formed into a film by sputtering on the silicon wafer thus obtained, thereby preparing a silicon wafer having a plurality of layers stacked on the silicon wafer. The film thickness of the ruthenium sample.

[0438] (Manufacturing of treatment liquid)

[0439] <Pretreatment of ion exchange resins: Production of hydrogen-type ion exchange resins>

[0440] 200 mL of sodium-type strongly acidic ion exchange resin (Amberlite IR-120BNa, manufactured by Organo Corporation) was placed in a glass column (BIO COLUMN CF-50TK, manufactured by AsOne) having an inner diameter of about 45 mm. Then, 1 L of 1N hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd., for volumetric analysis) was passed through the ion exchange resin column to exchange the ion exchange resin for the hydrogen type, and 1 L of ultrapure water was passed through the ion exchange resin column to wash the ion exchange resin.

[0441] <(a) Process>

[0442] Furthermore, 1 L of a 10% tetramethylammonium hydroxide solution was passed through 209 mL of the ion exchange resin exchanged to the hydrogen form to exchange ions from the hydrogen form to the tetramethylammonium form. After the ion exchange, 1 L of ultrapure water was passed through the ion exchange resin to wash it with water.

[0443] <(b) Process>

[0444] After adding 69 g of sodium hypochlorite pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd., special reagent grade) to a 2L fluororesin container, 931 g of ultrapure water was added to produce a 3.11 mass % sodium hypochlorite aqueous solution. The produced sodium hypochlorite aqueous solution was circulated through an ion exchange resin exchanged to a tetramethylammonium type to obtain 1000 g of a tetramethylammonium hypochlorite aqueous solution. 100 mg of tetradecyltrimethylammonium chloride was added to 999.9 g of the obtained tetramethylammonium hypochlorite aqueous solution to obtain a treatment solution having the composition described in Table 1.

[0445] <Evaluation>

[0446] The pH, effective chlorine concentration, and hypochlorite ion concentration of the obtained treatment solution were evaluated, and it was confirmed that the pH was 10 and the hypochlorite ion concentration was 2.15% by mass. In addition, the etching rate was evaluated by the above-mentioned "Calculation method of etching rate of ruthenium". The etching rate of ruthenium was calculated from the calculated etching rate. Time to prepare for etching The ruthenium film treated for a period of time was used as the ruthenium film for surface observation. The ruthenium surface was observed using an electron microscope at 100,000 times magnification. The results of the observation are shown in FIG. Figure 3 shown.

[0447] <Experimental Example 1-2>

[0448] In Experimental Example 1-1, the amount of ion exchange resin in step (a) was set to 564 mL, the flow rate of 10% tetramethylammonium hydroxide solution was set to 2 L, and the concentration of sodium hypochlorite aqueous solution in step (b) was set to 8.39% by mass to obtain a tetramethylammonium hypochlorite aqueous solution. Furthermore, as a pH adjustment step (c), a 25% tetramethylammonium hydroxide (TMAH) solution was added to the tetramethylammonium hypochlorite aqueous solution until the pH reached 11. 1 g of decyltrimethylammonium chloride was added to 999 g of the obtained tetramethylammonium hypochlorite aqueous solution to obtain a treatment solution having the composition described in Table 1. The evaluation results are shown in Table 2.

[0449] <Experimental Example 1-3>

[0450] In Example 1, the amount of ion exchange resin in step (a) was set to 705 mL, the flow rate of 10% tetramethylammonium hydroxide solution was set to 2 L, and the concentration of sodium hypochlorite aqueous solution in step (b) was set to 10.49% by mass to obtain a tetramethylammonium hypochlorite aqueous solution. Furthermore, as a pH adjustment step (c), a 25% tetramethylammonium hydroxide (TMAH) solution was added to the tetramethylammonium hypochlorite aqueous solution until the pH reached 12. 500 mg of lauryltrimethylammonium chloride was added to 999.5 g of the obtained tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having the composition described in Table 1. The evaluation results are shown in Table 2.

[0451] <Experimental Example 1-4>

[0452] The same operation as in Experimental Example 1-2 was performed to obtain a tetramethylammonium hypochlorite aqueous solution, and then 500 mg of octadecyltrimethylammonium chloride was added to 999.5 g of the tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having the composition shown in Table 1. The evaluation results are shown in Table 2.

[0453] <Experimental Example 1-5>

[0454] In Experimental Example 1-1, the amount of ion exchange resin in step (a) was set to 282 mL, and the concentration of the sodium hypochlorite aqueous solution in step (b) was set to 4.20% by mass to obtain a tetramethylammonium hypochlorite aqueous solution. Furthermore, as a pH adjustment step (c), a 25% tetramethylammonium hydroxide (TMAH) solution was added to the tetramethylammonium hypochlorite aqueous solution until the pH reached 11. 10 g of n-octyltrimethylammonium chloride was added to 990 g of the obtained tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having the composition described in Table 1. The evaluation results are shown in Table 2.

[0455] <Experimental Example 1-6>

[0456] After the same operation as in Experimental Example 1-1 was performed to obtain a tetramethylammonium hypochlorite aqueous solution, the tetramethylammonium hypochlorite aqueous solution was passed through a glass column filled with 50 mL of a sodium-type strongly acidic ion exchange resin (Amberlite IR-120BNa manufactured by Organo Corporation) exchanged to a hydrogen type as a pH adjustment step (c). 100 mg of tetradecyltrimethylammonium chloride was added to 999.9 g of the obtained tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having the composition described in Table 1. The evaluation results are shown in Table 2.

[0457] <Experimental Example 1-7>

[0458] The same operation as in Experimental Example 1-4 was performed to obtain a tetramethylammonium hypochlorite aqueous solution, and then 100 mg of hexadecyltrimethylammonium chloride was added to 999.9 g of the tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having the composition shown in Table 1. The evaluation results are shown in Table 2.

[0459] <Experimental Example 1-8>

[0460] Sodium hypochlorite pentahydrate (Wako Pure Chemical Industries, Ltd., special reagent grade) was dissolved in water so that the hypochlorite ion content was 2.15 mass %. 1 g of tetradecyltrimethylammonium chloride was added to 999 g of the obtained sodium hypochlorite aqueous solution to obtain a treatment liquid having the composition shown in Table 1. The evaluation results are shown in Table 2.

[0461] <Experimental Example 1-9>

[0462] In Experimental Example 1-1, the amount of ion exchange resin in step (a) was 282 mL, and the concentration of the sodium hypochlorite aqueous solution in step (b) was 4.20% by mass. 500 mg of didecyldimethylammonium chloride was added to 999.5 g of the obtained tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having the composition described in Table 1. The evaluation results are shown in Table 2.

[0463] <Experimental Example 1-10>

[0464] The same operation as in Experimental Example 1-9 was performed to obtain a tetramethylammonium hypochlorite aqueous solution, and then 100 mg of didodecyldimethylammonium chloride was added to 999.9 g of the tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having the composition shown in Table 1. The evaluation results are shown in Table 2.

[0465] <Reference Example 1-1>

[0466] A treatment liquid was prepared in the same manner as in Experimental Example 1-1 except that the alkylammonium salt represented by the formula (1) was not added, and the same evaluation as in Experimental Example 1-1 was performed.

[0467] The compositions of the treatment solutions prepared in the above Experimental Example 1 and Reference Example 1 are shown in Table 1, and the obtained results are shown in Table 2.

[0468] [Table 1]

[0469]

[0470] [Table 2]

[0471]

[0472] As shown in Table 2, in Experimental Examples 1-1 to 1-10 to which the processing liquid of the present invention was applied, the flatness of the ruthenium surface after etching was maintained, and the ruthenium surface can be suitably used as a processing liquid for semiconductor wafers. Figure 3 The electron microscope image of ruthenium after etching obtained in Experimental Example 1-1 is shown at 100,000 times magnification. It can be seen that the generation of RuO2 (particles) on the wafer surface is suppressed, and a flat ruthenium surface is obtained.

[0473] It is found that since Reference Example 1-1 does not add a surfactant, the flatness after etching is lower than that of Experimental Examples 1-1 to 1-10.

[0474] <Experimental Example 1-11>

[0475] The same operation as in Experimental Example 1-1 was carried out to obtain a tetramethylammonium hypochlorite aqueous solution, and then 1 g of tetraheptylammonium chloride was added to 999 g of the obtained tetramethylammonium hypochlorite aqueous solution to obtain a treatment liquid having a composition shown in Table 3.

[0476] <Reference Examples 1-2 to 1-3>

[0477] According to the procedure of Experimental Example 1-1, the treatment solution described in Table 3 was obtained.

[0478] [Table 3]

[0479]

[0480] From the results described in Table 3, it is understood that when a surfactant having no alkyl group with 7 or more carbon atoms in its structure is used as a surfactant, a preferred surface roughness cannot be obtained.

[0481] <Experimental Example 2 and Reference Example 2>

[0482] (Manufacturing of treatment liquid)

[0483] The treatment liquid was prepared as follows to form the composition described in Tables 4 and 5. Sodium hypochlorite (manufactured by Wako Pure Chemical Industries, Ltd.) or orthoperiodic acid (manufactured by FUJIFILM Wako Pure Chemical Corporation), a quaternary onium salt or a tertiary onium salt, an organic solvent, and ultrapure water were added to a 100 mL fluororesin container, and 60 mL of the treatment liquid adjusted to the pH described in the table was prepared using a 15 wt % HCl aqueous solution or a 1.0 mol / L NaOH aqueous solution. (In Experimental Examples 2-1 to 2-12 and Reference Examples 2-1 to 2-5 shown in Table 4, no organic solvent was added.) The effective chlorine concentration of the obtained treatment liquid was confirmed to be 2.0 wt %, and the treatment liquid described in Tables 4 and 5 was obtained.

[0484] (pH measurement method)

[0485] The pH of 10 mL of the treatment liquid prepared in each experimental example and each reference example was measured using a tabletop pH meter (LAQUAF-73, manufactured by Horiba, Ltd.) The pH measurement was performed after the temperature of the treatment liquid was stabilized at 25°C.

[0486] (Quantitative analysis of RuO4 gas)

[0487] The amount of RuO4 gas generated was measured using ICP-OES. 5 mL of the treatment solution was taken into a sealed container and immersed in a film at 25°C or 50°C to form a film with a thickness of A 10×20 mm Si wafer of ruthenium is immersed in the treatment solution until the ruthenium is completely dissolved. Then, air is circulated in the sealed container, and the gas phase in the sealed container is sampled into a container with an absorption liquid (1 mol / L NaOH) added, and the RuO4 gas generated during the immersion is captured in the absorption liquid. The amount of ruthenium in the absorption liquid is measured by ICP-OES to find the amount of Ru in the generated RuO4 gas. The complete dissolution of ruthenium on the Si wafer immersed in the treatment solution is confirmed by measuring the sheet resistance before and after immersion using a four-probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech) and converting it into film thickness.

[0488] (Confirmation of Sediment)

[0489] Take 10mL of the treatment solution in a sealed container and immerse it at 25℃ to form a film with a film thickness of Then, it was visually confirmed whether a precipitate was formed in the treatment solution.

[0490] <Experimental Examples 2-1 to 2-17 and Reference Examples 2-1 to 2-5>

[0491] The composition of the processing liquid and the evaluation results are shown in Tables 4 and 5. It should be noted that the Ru amount in Table 4 is a value obtained by dividing the weight of Ru contained in the RuO4 gas absorbing liquid by the area of ​​the wafer with Ru.

[0492] [Table 4]

[0493]

[0494] If we compare Experimental Example 2-1 with Reference Example 2-1 (pH 7.0), Experimental Example 2-2 with Reference Example 2-2 (pH 9.5), and Experimental Example 2-3 with Reference Example 2-3 (pH 12.0), it can be seen that at any pH, the addition of quaternary onium salt can reduce the amount of RuO4 gas generated.

[0495] In Experimental Examples 2-4 to 2-10, the onium salt used was different from that in Experimental Examples 2-1 to 2-3. For the quaternary onium salt or tertiary onium salt represented by the above formula (2) or (3), the onium salt having a carbon number, A + , X -When different onium salts are used, foaming of the treatment liquid is confirmed when the carbon number of the alkyl chain of the onium salt is greater than 10, but in any of Experimental Examples 2-4 to 2-10, the RuO4 gas suppression effect is obtained. For example, if the carbon number is used as an example, the concentration of the quaternary onium salt in the treatment liquid in Experimental Example 2-3 is 8.8wt%, while that in Experimental Example 2-4 is 0.5wt%. For Experimental Example 2-4 in which the carbon number of the quaternary onium salt is large, the gas suppression effect is obtained by adding a smaller amount of the quaternary onium salt.

[0496] Comparing Reference Example 2-4 with Experimental Example 2-11, it can be seen that even at 50° C., the generation of RuO 4 gas can be suppressed by adding an onium salt.

[0497] Comparing Reference Example 2-5 with Experimental Example 2-12, it can be seen that even when 1 mass % of orthoperiodic acid is used as the oxidant, the generation of RuO 4 gas can be suppressed by adding the onium salt.

[0498] <Reference Example 2-6>

[0499] The treatment solution of Reference Example 2-6 was prepared in the same manner as Reference Example 2-2 except that 1 wt% of 2,2,6,6-tetramethylpiperidinyl 1-oxyl (TEMPO) was added to Reference Example 2-2 shown in Table 4. The treatment solution was used to perform quantitative analysis of RuO4 gas. The result showed that the amount of Ru in the generated RuO4 gas was 40 μg / cm 2 TEMPO is considered to have a RuO 4 gas suppressing effect in Patent Document 7, but the RuO 4 gas suppressing effect could not be confirmed under alkaline conditions.

[0500] [Table 5]

[0501]

[0502] In Experimental Example 2-17, the generation of RuO4 gas can be suppressed, but precipitates that cause particles are generated in the processing liquid after the immersion treatment of the Si wafer with Ru. On the other hand, in Experimental Examples 2-13 to 2-16, in which acetonitrile or sulfolane having a lower relative dielectric constant than water was added, the generation of precipitates can be suppressed.

[0503] The treatment liquid was prepared as follows to form the composition described in Tables 6 to 9. Sodium hypochlorite (Wako Pure Chemical Industries, Ltd.), a quaternary onium salt or a tertiary onium salt, and ultrapure water were added to a 100 mL fluororesin container, and a 15 wt % HCl aqueous solution was used to adjust the pH described in the table to prepare 60 mL of the treatment liquid. The effective chlorine concentration of the obtained treatment liquid was confirmed to be 2.0 wt %, and the treatment liquid described in Tables 6 to 9 was obtained.

[0504] [Table 6]

[0505]

[0506] [Table 7]

[0507]

[0508] [Table 8]

[0509]

[0510] The results in Tables 6 to 8 show that the RuO4 gas suppression effect can be obtained by using a treatment solution containing a quaternary onium salt represented by formula (2). In addition, the results in Tables 6 and 7 show that the suppression effect increases as the concentration of the quaternary onium salt in the treatment solution increases.

[0511] [Table 9]

[0512]

[0513] From the results shown in Table 9, it can be seen that by using a treatment solution containing a quaternary onium salt represented by formula (2), the RuO4 gas inhibition effect can be obtained even if the pH of the treatment solution is different. In addition, it can be seen that the higher the concentration of the quaternary onium salt in the treatment solution, the higher the inhibition effect.

[0514] As a reference example, a treatment liquid containing an onium salt that does not satisfy the requirements of formulas (2) and (3) was prepared to have the composition described in the following Table 10. The preparation method was the same as that of the above-mentioned experimental example and reference example.

[0515] From the results in Table 10, it is understood that when an onium salt that does not satisfy the requirements of formulae (2) and (3) is contained, a sufficient gas generation suppressing effect cannot be obtained.

[0516] [Table 10]

[0517]

[0518] <Experimental Example 3 and Reference Example 3>

[0519] (Manufacturing of treatment liquid)

[0520] The treatment liquid was prepared as follows to form the composition described in Table 11. Sodium hypochlorite (manufactured by Wako Pure Chemical Industries, Ltd.), an onium salt, and ultrapure water were added to a 100 mL fluororesin container, and 60 mL of a treatment liquid having a pH of 12.0 was prepared using a 15 wt % HCl aqueous solution. The effective chlorine concentration of the obtained treatment liquid was confirmed to be 2.0 wt %, and the treatment liquid described in Table 11 was obtained.

[0521] (pH measurement method)

[0522] The pH of 10 mL of the treatment liquid prepared in the experimental examples and reference examples was measured using a tabletop pH meter (LAQUA F-73, manufactured by Horiba, Ltd.) The pH measurement was performed after the temperature of the treatment liquid was stabilized at 25°C.

[0523] (Quantitative analysis of RuO4 gas)

[0524] The amount of RuO4 gas generated was measured using ICP-OES. 5 mL of the treatment solution was taken into a sealed container and immersed in the film at 25°C to form a film with a thickness of A 10×20 mm Si wafer of ruthenium is immersed in the treatment solution until the ruthenium is completely dissolved. Then, air is circulated in the sealed container, and the gas phase in the sealed container is sampled into a container with an absorption liquid (1 mol / L NaOH) added, and the RuO4 gas generated during the immersion is captured in the absorption liquid. The amount of ruthenium in the absorption liquid is measured by ICP-OES to find the amount of Ru in the generated RuO4 gas. The complete dissolution of ruthenium on the Si wafer immersed in the treatment solution is confirmed by measuring the sheet resistance before and after immersion using a four-probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech) and converting it into film thickness.

[0525] <Experimental Examples 3-1 to 3-4 and Reference Example 3-1>

[0526] The composition of the processing liquid and the evaluation results are shown in Table 11. It should be noted that the Ru amount in Table 11 is a value obtained by dividing the weight of Ru contained in the RuO4 gas absorbing liquid by the area of ​​the wafer with Ru.

[0527] [Table 11]

[0528]

[0529] Comparing Experimental Examples 3-1 to 3-4 with Reference Example 3-1, it can be seen that the amount of RuO 4 gas generated can be reduced by adding an onium salt.

[0530] By changing the type of onium salt and following the same procedure as in Experimental Example 3-1, a treatment liquid was prepared so as to have the composition described in the following Table 12 and Table 13.

[0531] [Table 12]

[0532]

[0533] [Table 13]

[0534]

[0535] It can be seen from the results in Tables 12 and 13 that even if the onium salt has a structure different from the onium salt used in Experimental Examples 3-1 to 3-4, if it is an onium salt having the structure shown in formula (4), the effect of fully suppressing the generation of ruthenium-containing gas can be obtained when using a treatment liquid containing it.

[0536] <Experimental Example 4 and Reference Example 4>

[0537] According to the (manufacturing of the treatment liquid) shown in Experimental Example 3 and Reference Example 3, the treatment liquid was manufactured in a manner to form the composition described in Table 14. In addition, the pH measurement method of the treatment liquid and the quantitative analysis of RuO4 gas were performed according to the (pH measurement method) and (quantitative analysis of RuO4 gas) shown in Experimental Example 3 and Reference Example 3.

[0538] <Experimental Examples 4-1 to 4-3 and Reference Example 4-1>

[0539] The composition of the processing liquid and the evaluation results are shown in Table 14. It should be noted that the amount of Ru in Table 14 is a value obtained by dividing the weight of Ru contained in the RuO4 gas absorbing liquid by the area of ​​the wafer with Ru.

[0540] [Table 14]

[0541]

[0542] From the results in Table 14, it can be seen that when a treatment liquid containing the onium salt represented by the formula (5) is used, the generation of a gas containing ruthenium can be sufficiently suppressed.

[0543] <Experimental Example 5 and Reference Example 5>

[0544] <Experimental Examples 5-1 to 5-11>

[0545] (Treatment agent for waste liquid containing ruthenium, and production of mixed solution of waste liquid containing ruthenium)

[0546] Sodium hypochlorite (manufactured by Wako Pure Chemical Industries, Ltd.) and ultrapure water were added to a fluororesin container, and the pH was adjusted to the pH shown in Table 15 using a 15 wt % HCl aqueous solution or a 4 wt % NaOH aqueous solution, thereby obtaining a Ru etching treatment solution having an effective chlorine concentration of 2.0 wt %. A film having a thickness of 1.0 % was formed by immersing the film in 1 L of the obtained treatment solution at 25°C. The ruthenium on the 300 mm Si wafer was recovered into the waste tank after 10 minutes.

[0547] Then, sodium hypochlorite (manufactured by Wako Pure Chemical Industries, Ltd.), an onium salt, and ultrapure water were added to a fluororesin container, and then a 15 wt % HCl aqueous solution or a 4 wt % NaOH aqueous solution was used to adjust the pH to that shown in Table 15, thereby obtaining a treatment agent for waste liquid containing ruthenium having an effective chlorine concentration of 2.0 wt %. 1 L of the obtained treatment agent for waste liquid containing ruthenium was mixed into a waste liquid tank at 25° C., thereby obtaining a waste liquid containing 6.0×10 -4 The treatment agent for the waste liquid containing ruthenium described in Table 15 with ruthenium in mol / L, and the mixed liquid of the waste liquid containing ruthenium (hereinafter also simply referred to as the mixed liquid).

[0548] (Quantitative analysis of RuO4 gas)

[0549] The amount of RuO4 gas produced is measured using ICP-OES. Take 5 mL of the treatment solution in a closed container. Air is circulated in the closed container for 15 minutes, and the gas phase in the closed container is sampled into a container to which an absorption liquid (1 mol / L NaOH) is added, and the RuO4 gas produced by the mixed solution is captured in the absorption liquid. The amount of ruthenium in the absorption liquid is measured by ICP-OES to determine the amount of Ru in the generated RuO4 gas. The complete dissolution of ruthenium on the treated Si wafer is confirmed by measuring the sheet resistance before and after immersion using a four-probe resistance measuring device (Loresta-GP, Mitsubishi Chemical Analytech Co., Ltd.) and converting it into film thickness.

[0550] <Experimental Examples 5 to 12>

[0551] The treatment agent for the waste liquid containing ruthenium and the mixed solution of the waste liquid containing ruthenium described in Table 15 were obtained by the same method as in Experimental Example 5-1. The effective chlorine concentration was 4.0wt% for the Ru etching treatment liquid and 0% (excluding oxidant) for the treatment agent for the waste liquid containing ruthenium. The quantitative analysis of RuO4 gas was carried out by the same steps as in Experimental Example 5-1.

[0552] <Experimental Examples 5-13-5-15>

[0553] By the same method as in Experimental Example 5-1, a Ru etching treatment solution having an effective chlorine concentration of 4.0 wt % was obtained. 1 L of the obtained treatment solution was added to a film having a film thickness of The ruthenium was passed through the surface of a 300 mm Si wafer, rinsed with 1 L of ultrapure water, and then recovered in a waste liquid tank. Next, 2 L of a treatment agent containing ruthenium with an effective chlorine concentration of 2.0 wt% obtained by the same method as in Experimental Example 5-1 was mixed into the waste liquid tank, thereby obtaining a 6.0×10 -4The treatment agent for the waste liquid containing ruthenium and the mixed solution of the waste liquid containing ruthenium described in Table 15 with ruthenium mole / L. The quantitative analysis of RuO4 gas was carried out by the same procedure as in Experimental Example 5-1.

[0554] <Reference example 5-1 to 5-4>

[0555] Sodium hypochlorite (manufactured by Wako Pure Chemical Industries, Ltd.) and ultrapure water were added to a fluororesin container, and then a 15 wt % HCl aqueous solution or a 4 wt % NaOH aqueous solution was used to adjust the pH to that shown in Table 16, thereby obtaining a treatment solution for ruthenium etching having an effective chlorine concentration of 2.0 wt %. A film having a thickness of 1.0 wt % was formed by immersing 1 L of the obtained treatment solution at 25°C. After 10 minutes, the 300 mm Si wafer containing ruthenium was recovered into the waste tank, thereby obtaining a 6.0×10 -4 The ruthenium-containing waste liquid described in Table 16 of ruthenium mole / L. The quantitative analysis of RuO4 gas was carried out by the same procedure as in Experimental Example 5-1.

[0556] <Reference Example 5~5>

[0557] A treatment solution for ruthenium etching having an effective chlorine concentration of 4.0 wt % was obtained by the same method as in Reference Example 5-1. 1 L of the obtained treatment solution was added to a film having a film thickness of The ruthenium was passed through the surface of a 300 mm Si wafer, rinsed with 1 L of ultrapure water, and recovered in a waste tank, thereby obtaining a 6.0 × 10 -4 The ruthenium-containing waste liquid recorded in Table 16 with ruthenium in moles / L.

[0558] [Table 15]

[0559]

[0560] [Table 16]

[0561]

[0562] As can be seen from the results of Tables 15 and 16, when a treatment solution containing any one of the onium salts shown in formulas (2) to (5) is added to a waste liquid containing ruthenium, the generation of ruthenium-containing gas is suppressed. It can be seen from this that when the treatment solution of each embodiment of the present invention is used for the treatment of a waste liquid containing ruthenium, since the generation of ruthenium-containing gas is suppressed, it can be suitably used for the treatment of a waste liquid containing ruthenium.

[0563] Description of Reference Numerals

[0564] 1 Matrix

[0565] 2 Interlayer insulation film

[0566] 3 Ruthenium

Claims

1. A semiconductor wafer processing liquid, characterized in that: The processing liquid comprises an onium salt formed by an onium ion and an anion, and the processing liquid is used in a semiconductor wafer forming process and is used to etch a metal contained in the semiconductor wafer, and comprises: (A) Hypochlorite ion, (B) an alkylammonium salt represented by the following formula (1), In formula (1), a is an integer of 6 to 20, R 1 , R 2 , R 3 are independently an alkyl group having 1 to 20 carbon atoms, X - is a fluoride ion, a chloride ion, an iodide ion, a hydroxide ion, a nitrate ion, a phosphate ion, a sulfate ion, a hydrogen sulfate ion, a perchlorate ion, an acetate ion, a fluoroborate ion, or a trifluoroacetate ion, The concentration of the alkylammonium salt represented by the formula (1) in (B) is 0.0001 to 10% by mass. 2 . The treatment liquid according to claim 1 , comprising (C) at least one ammonium ion selected from the group consisting of tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetrabutylammonium ion.

3. The treatment liquid according to claim 1 or 2, wherein The metal contained in the semiconductor wafer is ruthenium. 4 . An etching method comprising the step of bringing the processing liquid according to claim 1 into contact with a semiconductor wafer.

5. A semiconductor wafer processing liquid, characterized in that: Contains hypochlorite ions and an onium salt formed by an onium ion and an anion, wherein the onium salt is a quaternary onium salt represented by formula (2) or a tertiary onium salt represented by formula (3), In formula (2), 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 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group; wherein R 1 , R 2 , R 3 , R 4 In the case of an alkyl group, R 1 , R 2 , R 3 , R 4 The number of carbon atoms of at least one alkyl group in the aryl group is 2 or more; in addition, at least one hydrogen in the ring of the aryl group in the aryl group and the aralkyl group is optionally substituted 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, wherein at least one hydrogen in the alkyl group having 1 to 10 carbon atoms, the alkenyl group having 2 to 10 carbon atoms, the alkoxy group having 1 to 9 carbon atoms, or the alkenyloxy group having 2 to 9 carbon atoms is optionally substituted by fluorine or chlorine; in formula (3), A + is the sulfonium ion, 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; wherein R 1 , R 2 , R 3 In the case of an alkyl group, R 1 , R 2 , R 3 The number of carbon atoms of at least one alkyl group in the aryl group is 2 or more; in addition, at least one hydrogen in the ring of the aryl group in the aryl group and the arylalkyl group is optionally substituted 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, wherein at least one hydrogen in the 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 is optionally substituted by fluorine or chlorine; in formula (2) or formula (3), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion, The concentration of the onium salt in the treatment solution is 0.0001 to 50% by mass.

6. The treatment liquid according to claim 5, wherein The quaternary onium salt is a salt formed of at least one ammonium ion selected from tetrapropylammonium ion, tetrabutylammonium ion, or tetrapentylammonium ion.

7. A semiconductor wafer processing liquid, characterized in that: The invention relates to a catalyst comprising a hypochlorite ion and an onium salt formed by an onium ion and an anion, wherein the onium salt is 1,3-dimethylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-methyl-3-n-octylimidazolium chloride, 1,3-di(2,4,6-trimethylphenyl)imidazolium chloride, 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride, 1,3-dicyclohexylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-methyl-3-n-octylimidazolium chloride, 1,3-di(2,4,6-trimethylphenyl)imidazolium chloride, 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride, 1,3-dicyclohexylimidazolium chloride, 1-butyl -1-methylpyrrolidinium chloride, 1-ethyl-1-methylpyrrolidinium chloride, 1,1-dimethylpiperidinium chloride, 1-butyl-1-methylpiperidinium chloride, 5-azoniaspiro[4,4]nonane chloride, 1-methylpyridinium chloride, 1-ethylpyridinium chloride, 1-propylpyridinium chloride, 1-fluoropyridinium tetrafluoroborate, 1-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate, 1-fluoro-2,6-dichloropyridinium tetrafluoroborate or N-tert-butyl-5-methylisoxazolium perchlorate, The concentration of the onium salt in the treatment solution is 0.0001 to 50% by mass.

8. A semiconductor wafer processing liquid, characterized in that: Contains hypochlorite ions and an onium salt formed by an onium ion and an anion, wherein the onium salt is an onium salt represented by formula (5), In formula (5), A + are independently ammonium ions or phosphonium ions, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 are independently an alkyl group having 1 to 25 carbon atoms, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group; at least one hydrogen in the ring of the aryl group and the aryl group in the aralkyl group is optionally substituted 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, wherein at least one hydrogen in the alkyl group having 1 to 10 carbon atoms, the alkenyl group having 2 to 10 carbon atoms, the alkoxy group having 1 to 9 carbon atoms, or the alkenyloxy group having 2 to 9 carbon atoms is optionally substituted by fluorine or chlorine; in formula (5), X - is fluoride ion, chloride ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, bisulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, bicarbonate ion, fluoroborate ion, or trifluoroacetate ion, and a is an integer of 1 to 10, The concentration of the onium salt in the treatment solution is 0.0001 to 50% by mass.

9. The treatment liquid according to any one of claims 5 to 8, wherein The treatment liquid contains an oxidizing agent.

10. The treatment liquid according to any one of claims 1, 5 to 8, wherein The treatment liquid contains hypochlorite ions, and the concentration of the hypochlorite ions is 0.05 to 20.0 mass %. 11 . The treatment liquid according to claim 5 , further comprising an organic solvent.

12. The treatment liquid according to claim 11, wherein The relative dielectric constant of the organic solvent is 45 or less.

13. The treatment liquid according to claim 11, wherein The organic solvent is sulfolanes, alkyl nitriles, halogenated alkanes and ethers.

14. The treatment liquid according to any one of claims 1 to 2, 5 to 8, and 12, wherein The pH at 25°C is more than 7 and less than 14.

0.

15. Use of the processing liquid according to any one of claims 5 to 14 for etching a semiconductor wafer containing ruthenium. 16 . A method for etching a semiconductor wafer, comprising the step of bringing the processing liquid according to claim 5 into contact with a semiconductor wafer containing ruthenium.

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