Ruthenium oxide gas absorption solution, ruthenium oxide analysis method and trap device, and quantitative analysis device

Abstract

[Problem] To provide an absorbing liquid which is convenient, can be applied to any processing conditions, and can increase the sensitivity of ruthenium oxide quantification. [Solution] This ruthenium oxide gas absorbing liquid is characterized by containing an organic alkaline solution which includes a ligand and / or an onium salt composed of onium ions and anions, at least some of which are hydroxide ions, wherein the concentration of the hydroxide ions falls within the range of 1×10-7 mol / L to 6 mol / L (exclusive of 1×10-7).

Description

[Technical field]

[0001] The present invention relates to a novel ruthenium oxide gas absorbing solution capable of improving the analytical accuracy of ruthenium-containing gas generated when processing semiconductor wafers containing ruthenium in the manufacturing process of semiconductor elements, and to an analytical method, trapping device, and quantitative analysis device using the absorbing solution. [Background technology]

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

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

[0004] Incidentally, even when ruthenium is selected as the wiring material in the process of forming wiring in a semiconductor element, the wiring is formed by dry or wet etching in the same manner as in the case of conventional wiring materials.

[0005] However, regardless of the method used, ruthenium is converted into highly volatile RuO 4 (Ru is +8. Hereinafter referred to as ruthenium oxide), part of which is gasified and released into the gas phase.

[0006] RuO 4is a strong oxidizing agent that is harmful to the human body and poses health risks. It also has a very strong oxidizing power and easily reacts with organic matter, the surfaces of containers, and water vapor in the air to form RuO 2 (Ru is +4) changes to RuO 2 Generates particles. RuO 2 Particles accumulate inside semiconductor manufacturing equipment during etching and MP processing, for example inside chambers, wafer fixing jigs, and exhaust equipment, making periodic cleaning and replacement necessary, which can reduce product yields.

[0007] Therefore, it is considered preferable that the amount of ruthenium oxide generated is as small as possible, and most preferably zero, and etching agents and CMP slurries that are less likely to generate ruthenium oxide gas are being developed.

[0008] Accordingly, in order to enhance safety and increase product yield, an analytical method for quantifying the amount of ruthenium oxide gas generated is also desired. For example, Non-Patent Document 1 discloses a method for quantifying ruthenium oxide that utilizes a Ru radioisotope contained in ruthenium oxide gas.

[0009] Patent Document 1 also gives an example of combining a semiconductor manufacturing device (dry etching device) with a ruthenium oxide gas concentration measuring device, and discloses a gas detection method that uses N,N-diethyl-p-phenylenediamine as a color developing agent in combination with an antioxidant and a moisture-proofing agent. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] Journal of the Atomic Energy Society of Japan, 1986, Vol.28, No.6, p493-500 [Patent documents]

[0011] [Patent Document 1] JP 2002-267606 A Summary of the Invention [Problem to be solved by the invention]

[0012] However, according to the investigations of the present inventors, it was found that the conventional analytical methods described in the prior art documents have room for improvement in the following respects. For example, the method of Non-Patent Document 1 is highly sensitive, but is not easy to implement because it evaluates activated ruthenium. In addition, Patent Document 1 utilizes the fact that a dye is oxidized by ruthenium oxide to produce a color, but since it only checks by color production, there is a problem that even if the color is produced by an oxidizing agent other than ruthenium oxide, it will be detected as ruthenium oxide. Furthermore, when water vapor is contained in the atmosphere, the error becomes large, so it is particularly unsuitable for quantifying ruthenium oxide generated from wet etching or CMP slurry. In addition, there is a problem that the lower limit of detection is high.

[0013] Therefore, there has been a need for a simple method for quantifying ruthenium oxide with a low lower limit of determination that can be applied under any processing conditions. [Means for solving the problem]

[0014] Therefore, as a quantitative method that does not require activation, we used a gas trap solution containing RuO 4 The present inventors have investigated ways to solve the above problems using analytical methods. There are three types of commonly known gas trapping solutions: acidic (hydrochloric acid), alkaline (aqueous sodium hydroxide solution), and low polarity solvent (carbon tetrachloride). The state of dissolved ruthenium oxide changes depending on the properties (pH, polarity) of the gas trapping solution. In hydrochloric acid, [RuCl 6 ] 2- or [RuCl 5 ] 2- In NaOH, RuO 4 2- , RuO 4 - In carbon tetrachloride, RuO4 It is believed to exist in.

[0015] The inventors' investigations revealed that the state of ruthenium dissolved in the gas trap solution affects (1) the efficiency of collecting ruthenium oxide gas and (2) the efficiency of excitation by ICP (inductively coupled plasma).

[0016] After further investigation, it was found that stable collection and quantification could be achieved by trapping ruthenium oxide with sodium hydroxide, converting it into a ruthenium chloride complex ion under acidic conditions with hydrochloric acid, and then exciting and measuring it with an ICP.

[0017] However, when NaOH is used as a gas trapping solution, a large amount of sodium is present in the gas trapping solution. This creates a new problem in that the highly sensitive ICP-MS cannot be used because of interference from Na. To address this, there is no choice but to use ICP-OES, which is not interfered with by Na, but this leaves the problem of poor sensitivity, i.e. a high lower limit of quantification.

[0018] Therefore, the present inventors discovered that by using an organic alkali such as tetramethylammonium hydroxide (TMAH) instead of NaOH, ICP-MS can be used and high sensitivity can be achieved, leading to the completion of the present invention.

[0019] That is, the present invention is configured as follows. [1] An organic alkaline solution containing an onium salt composed of an onium ion and an anion at least part of which is a hydroxide ion, the hydroxide ion concentration being 1×10 -7 A ruthenium oxide gas absorbing solution having a concentration in the range of more than mol / L and not more than 6 mol / L. [2] The ruthenium oxide gas absorbing solution according to [1], wherein the onium ion is a quaternary onium ion represented by formula (1) or a tertiary onium ion represented by formula (2).

[0020] [ka]

[0021] [ka] (In formula (1), A + is an ammonium ion or a phosphonium ion, and R 1 , R 2 , R 3 , R 4 is an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R 1 , R 2 , R 3 , R 4 When R is an alkyl or aryl group, 1 , R 2 , R 3 , R 4 At least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine. + is a sulfonium ion, and R 1 , R 2 , R 3 is an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. In addition, in the aryl group in the aralkyl group and in the ring of the aryl group, at least one hydrogen atom may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine. [3] The onium ion is represented by formula (1), and R 1 , R 2, R 3 , R 4 is a quaternary onium ion which is an alkyl group having 1 to 4 carbon atoms. [2] Ruthenium oxide gas absorbing solution. [4] The ruthenium oxide gas absorbing solution according to [2] or [3], wherein the quaternary onium ion is an ammonium ion. [5] The ruthenium oxide gas absorbing solution according to [4], wherein the ammonium ion is a tetraalkylammonium ion. [6] The ruthenium oxide gas absorbing solution according to [5], wherein the tetraalkylammonium ion is at least one tetraalkylammonium ion selected from the group consisting of tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetrabutylammonium ion. [7] The ruthenium oxide gas absorbing solution of [1] further contains an onium salt composed of an onium ion and an anion other than hydroxide as a ruthenium oxide gas generation inhibitor. [8] The ruthenium oxide gas absorbing solution according to [7], wherein the anion is at least one selected from the group consisting of a fluoride ion, a chloride ion, an iodide 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, and a trifluoroacetate ion. [9] The ruthenium oxide gas absorbing solution according to claim 1, further comprising a ligand that coordinates with ruthenium as a ruthenium oxide gas generation inhibitor.

[10] The ruthenium oxide gas absorbing solution according to [9], wherein the ligand coordinating with the ruthenium is oxalic acid, dimethyl oxalate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, succinic acid, acetic acid, butane-1,2,3,4-tetracarboxylic acid, dimethylmalonic acid, glutaric acid, diglycolic acid, citric acid, malonic acid, 1,3-adamantanedicarboxylic acid, or 2,2-bis(hydroxymethyl)propionic acid.

[11] The concentration of the onium ion is 1×10 -3 The ruthenium oxide gas absorbing solution according to any one of [1] to

[10] , characterized in that the ruthenium oxide gas absorbing solution has a dielectric constant of 45 to 8 mol / L.

[12] The ruthenium oxide gas absorbing solution according to any one of [1] to

[11] , further comprising water or an organic solvent.

[13] The ruthenium oxide gas absorbing solution according to

[12] , characterized in that the organic solvent has a dielectric constant of 45 or less.

[14] The ruthenium oxide gas absorbing solution according to

[12] or

[13] , wherein the organic solvent is at least one selected from the group consisting of sulfolanes, alkylnitriles, halogenated alkanes, ethers, esters, aldehydes, ketones, and alcohols.

[15] The ruthenium oxide gas absorbing solution according to any one of

[12] to

[14] , wherein the organic solvent has a concentration of 0.1 mass % or more in the treatment solution.

[16] A method for analyzing ruthenium oxide in a gas to be treated, comprising contacting the gas to be treated containing ruthenium oxide gas with the ruthenium oxide gas absorbing solution according to any one of [1] to

[15] above to recover ruthenium oxide gas from the gas to be treated, and then analyzing the amount of ruthenium oxide in the ruthenium oxide gas absorbing solution.

[17] The analytical method according to

[16] , wherein the gas to be treated originates from a semiconductor chemical used in processing a semiconductor material containing ruthenium metal.

[18] A trap device which is arranged in an exhaust path in a processing step of a semiconductor device containing ruthenium metal, and which comprises a trap unit for recovering a ruthenium oxide component in exhaust gas, and which is characterized in that the trap unit is equipped with a container for charging the ruthenium oxide gas absorbing solution according to any one of [1] to

[17] as a trapping means for ruthenium oxide contained in the exhaust gas, a supply means, and a drain pipe for discharging the ruthenium oxide gas absorbing solution after absorption.

[19] A trap device which is disposed in an exhaust path in a processing step of a semiconductor device containing ruthenium metal, and which has a trap section for recovering a ruthenium oxide component in an exhaust gas, and which is provided in the trap section with a container for receiving the ruthenium oxide gas absorbing solution according to any one of [1] to

[17] as a means for capturing ruthenium oxide contained in the exhaust gas, a supply means, and a drain pipe for discharging the ruthenium oxide gas absorbing solution after absorption; The apparatus for quantitatively analyzing ruthenium oxide gas comprises an analyzing means for quantitatively analyzing the ruthenium oxide component in the absorbing liquid discharged from the trap device.

[20] The quantitative analysis apparatus according to

[19] , characterized in that the analytical means is an analytical means using inductively coupled plasma (ICP) optical emission spectroscopy, ICP mass spectrometry, or ultraviolet-visible spectroscopy (UV-VIS). Effect of the Invention

[0022] According to the present invention, by using a solution containing a metal-free organic alkali as a ruthenium oxide gas absorbing solution, highly sensitive quantitative determination of ruthenium oxide by ICP-MS is possible. In addition, since the ruthenium oxide gas absorbing solution contains a specific ruthenium oxide gas generation inhibitor, the ruthenium oxide collection efficiency is increased, making it possible to reduce the amount of ruthenium oxide gas absorbing solution, and enabling high sensitivity quantification without the need for operations such as concentrating the absorbing solution. This is effective not only for the highly sensitive ICP-MS but also for ICP-OES.

[0023] Furthermore, if the ruthenium oxide gas absorbing solution contains a ruthenium oxide gas generation inhibitor, the cations contained in the inhibitor are converted to RuO 4 2- , RuO 4 - Since it forms an ion pair with ruthenium oxide, it becomes possible to efficiently collect ruthenium oxide.

[0024] Furthermore, according to the present invention, there are provided an analytical method, a trapping device, and an analytical device that use this ruthenium oxide gas absorbing solution to enable efficient, simple, and highly sensitive analysis of ruthenium oxide in a gas to be treated that is generated in a semiconductor processing step. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 shows a schematic diagram of an apparatus evaluated in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, embodiments of the present invention will be described, but the present invention should not be construed as being limited to these descriptions. (Ruthenium oxide gas absorbing solution) The ruthenium oxide gas absorbing solution of the present invention contains an organic alkali containing an onium salt consisting of an onium ion and an anion, at least a part of which is a hydroxide ion. By using an organic alkali, it is possible to perform high-sensitivity analysis of ruthenium by ICP-MS. ICP-MS has the potential to perform high-sensitivity analysis of ruthenium, but when a solution containing an inorganic alkali such as NaOH or KOH is used as the gas absorbing solution, it is difficult to perform trace analysis of ruthenium because it is interfered with by Na and K. Therefore, by using an organic alkali such as tetramethylammonium hydroxide (TMAH) instead of an inorganic alkali, interference by Na and the like can be eliminated, making it possible to perform high-sensitivity analysis of ruthenium by ICP-MS.

[0027] The onium ions are quaternary onium ions, tertiary onium ions, secondary onium ions, and hydrogen-substituted onium ions, such as cations such as ammonium ions, phosphonium ions, fluoronium ions, chloronium ions, bromonium ions, iodonium ions, oxonium ions, sulfonium ions, selenonium ions, telluronium ions, arsonium ions, stibonium ions, and bismuthonium ions.

[0028] In the present invention, the onium ion is preferably a quaternary onium ion represented by formula (1) or a tertiary onium ion represented by formula (2).

[0029] [ka]

[0030] [ka] In formula (1), A + is an ammonium ion or a phosphonium ion.

[0031] R 1 , R 2 , R 3 , R 4 is an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group, provided that R 1 , R 2 , R 3 , R 4 When R is an alkyl or aryl group, 1 , R 2 , R 3 , R 4 At least one hydrogen atom in R may be replaced with a hydroxyl group, a carboxyl group, a cyano group, an amino group, a thiol group, a halogen group, or a sulfonic acid group. 1 , R 2 , R 3 , R 4 When R is an alkyl or aryl group, 1 , R 2 , R 3 , R 4 A carbonyl group may be contained therein. Furthermore, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine.

[0032] In formula (2), A + is a sulfonium ion, and R 1 , R 2 , R 3 is an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. In addition, in the aryl group in the aralkyl group and in the ring of the aryl group, at least one hydrogen atom may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine.

[0033] Since the ruthenium oxide gas absorbing solution of the present invention is alkaline, the absorbed ruthenium oxide is RuO 4 - Or RuO 4 2- Anions such as RuO 4 - It exists as RuO. 4 - and the like electrostatically interact with onium ions in the ruthenium oxide gas absorbing solution to form ion pairs and can be stably present in the ruthenium oxide gas absorbing solution. For this reason, it is believed that the ruthenium oxide gas absorbing solution containing onium ions efficiently absorbs ruthenium oxide gas.

[0034] R in the above formula (1) or (2) 1 , R 2 , R 3 , R 4 The alkyl group can be used without any particular limitation as long as it has 1 to 25 carbon atoms. The larger the carbon number, the more the onium ion becomes RuO 4 - etc., so it can be efficiently used as RuO 4 On the other hand, the larger the carbon number, the bulkier the onium ion becomes, so RuO 4 -The solubility of the ion pair with RuO etc. in the ruthenium oxide gas absorption solution decreases, and a precipitate is formed. Since this precipitate affects the excitation by ICP, it is preferable that the precipitate does not form. On the other hand, when the number of carbon atoms is small, the onium ion and RuO 4 - The interaction with RuO etc. becomes weaker. 4 Although the gas collection effect is weakened, the foaming of the ruthenium oxide gas absorbing solution is suppressed, making it easier to handle.

[0035] Therefore, in the onium salt of an organic alkali, the number of carbon atoms in the alkyl group in the formula (1) or (2) is preferably 1 to 25, more preferably 1 to 10, and most preferably 1 to 4. In the case of an onium salt having an alkyl group with such a carbon number, RuO 4 - RuO 4 Since the gas can be collected in the absorbing liquid and precipitates are unlikely to form, the absorbing liquid can be suitably used.

[0036] R in the above formula (1) or (2) 1 , R 2 , R 3 , R 4 The aryl group includes not only aromatic hydrocarbons but also heteroaryls containing heteroatoms, and is not particularly limited, but is preferably a phenyl group or a naphthyl group.

[0037] The above-mentioned quaternary onium ion is preferably an ammonium ion or a phosphonium ion that can exist stably in the treatment liquid. In general, the alkyl chain length of the ammonium ion or the phosphonium ion can be easily controlled, and further, it is easy to introduce an allyl group or an aryl group. This makes it possible to control the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surface activity, etc. of the ammonium ion or the phosphonium ion. Such an ammonium ion or a phosphonium ion is RuO 4 -Since the onium salt easily forms an ion pair with the ruthenium oxide gas absorbing solution, the ruthenium oxide gas absorbing solution containing the onium salt can efficiently collect the ruthenium oxide gas.

[0038] The tertiary onium ion is preferably a sulfonium ion that can exist stably in the treatment solution. In general, the alkyl chain length of the sulfonium ion can be easily controlled, and further, it is easy to introduce an allyl group or an aryl group. This makes it possible to control the size, symmetry, hydrophilicity, hydrophobicity, stability, solubility, charge density, surface activity, etc. of the sulfonium ion. Such a sulfonium ion is RuO 4 - Since the onium salt easily forms an ion pair with the ruthenium oxide gas absorbing solution, the ruthenium oxide gas absorbing solution containing the onium salt can efficiently collect the ruthenium oxide gas.

[0039] R in the above formula (1) or (2) 1 , R 2 , R 3 , R 4 may be the same group or different groups, but from the standpoint of industrial availability, stability, and the like, it is preferable that they are the same group.

[0040] In the present invention, the onium ion is represented by the formula (1) and R 1 , R 2 , R 3 , R 4 is preferably a quaternary onium ion which is an alkyl group having 1 to 4 carbon atoms, and more preferably an ammonium ion. The ammonium ion is preferably a tetraalkylammonium ion, and the tetraalkylammonium ion is preferably at least one ammonium ion selected from a tetramethylammonium ion, a tetraethylammonium ion, a tetrapropylammonium ion, and a tetrabutylammonium ion.

[0041] RuO in the gas absorption liquid 4- As mentioned above, the onium ion added to capture the above is RuO 4 - It is sufficient if it causes electrostatic interaction with the above. Therefore, the structure of the onium ion is not limited to the quaternary onium ion represented by the above formula (1) or the tertiary onium ion represented by the formula (2). Specifically, the onium salt containing the onium ions represented by the formulas (1) and (2) and different from the organic alkali may be, for example, an onium ion having a cyclic structure such as an imidazolium ion, a pyrrolidinium ion, a pyridinium ion, a piperidinium ion, or an oxazolium ion, or a dication represented by a hexamethonium ion.

[0042] These onium ions are combined with anions, i.e., added as onium salts to the ruthenium oxide gas absorbing solution, and ions containing ruthenium atoms (RuO 4 - By trapping these elements, the efficiency of collecting ruthenium oxide is improved.

[0043] The organic alkali composed of the above onium ions and hydroxide ions has a hydroxide ion concentration of 1×10 -7 The organic alkali is contained in the absorbent so as to have a concentration of more than 1×10 mol / L and not more than 6 mol / L. Preferably, the upper limit of the concentration is 5 mol / L, and more preferably 4 mol / L, at which concentration the viscosity of the absorbing solution is low and handling is easy. More preferably, the upper limit of the concentration is 2.8 mol / L, and at this concentration, a highly stable and highly pure organic alkali can be obtained industrially at low cost. The lower limit of the concentration is preferably 1×10 -4 mol / L, more preferably 1×10 -3 mol / L, and when it is in this range, ruthenium oxide is RuO 4 - , RuO 4 2- Since it exists stably as such, the trapping efficiency in the absorption liquid is improved.

[0044] The concentration of the onium ions is 1×10 -7 mol / L to 8 mol / L, preferably 1×10 -3 A certain amount of onium ions is necessary to efficiently trap ruthenium oxide gas, but if the concentration is too high, the onium salt will not dissolve and the onium ions and RuO 4 - Ion pairs with, etc. may precipitate.

[0045] The onium ion concentration in the absorbing solution is the total concentration of onium ions derived from organic alkali and onium ions derived from onium salts other than organic alkali. (Ruthenium oxide gas generation inhibitor) For the purpose of adjusting the onium ion concentration to the above range, an onium salt other than hydroxide may be added to the ruthenium oxide gas absorbing solution. Such an onium salt other than hydroxide is called a ruthenium oxide gas generation inhibitor. In consideration of the onium ion concentration and hydroxide ion concentration, the concentration of the onium salt other than hydroxide is preferably in the range of 0.0001 to 3 mol / L.

[0046] The onium salt added as the ruthenium oxide gas generation inhibitor is composed of an onium ion and an anion, and the anion is different from that of the onium hydroxide salt constituting the organic alkali. Examples of the onium ion include the same as those mentioned above. The onium ion constituting the onium salt that is the ruthenium oxide gas generation inhibitor may be the same as or different from the onium ion constituting the organic alkali.

[0047] In the onium salt of the ruthenium oxide gas generation inhibitor, the alkyl group in the formula (1) or (2) preferably has 1-25 carbon atoms, more preferably 2-10 carbon atoms, and most preferably 3-6 carbon atoms.

[0048] The anion is not particularly limited as long as it is other than a hydroxide ion, but specifically, at least one selected from a fluoride ion, a chloride ion, an iodide 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, and a trifluoroacetate ion is preferred.

[0049] Furthermore, a ligand capable of coordinating with ruthenium may be added as a ruthenium oxide gas generation inhibitor. (Ligands capable of coordinating with ruthenium) In addition, the ruthenium oxide gas absorbing solution can be added with a ligand (hereinafter, sometimes referred to as "ligand") capable of coordinating with ruthenium to improve the collection efficiency of ruthenium oxide. Examples of such ligands include compounds having atoms such as nitrogen, phosphorus, oxygen, or sulfur, such as amino groups, phosphino groups, carboxyl groups, carbonyl groups, and thiol groups, but are not limited thereto. Due to the difference in electronegativity between ruthenium and oxygen in ruthenium oxide, ruthenium exists in a state in which the charge is biased toward the positive side. When the lone electron pair contained in the ligand is coordinated to this ruthenium, ruthenium oxide can exist more stably in the ruthenium oxide gas absorbing solution, and it is considered that the collection efficiency of ruthenium oxide is improved.

[0050] In addition, in the case of a ligand having a C=O bond, for example, a carbonyl group or a carboxyl group, the following gas suppression mechanism also occurs, so that the collection efficiency of ruthenium oxide is increased. Ruthenium oxide is generally known as a metal oxide with strong electrophilicity because the electronegativity of the ruthenium constituting it is high among metals. Since metal oxides with strong electrophilicity are easily coordinated to unsaturated bond carbon, ruthenium is coordinated to a compound containing a carbonyl group having an unsaturated bond. The chemical species in which such a compound containing a carbonyl group and ruthenium oxide interact with each other is stable in the ruthenium oxide gas absorbing solution, so that the collection efficiency of ruthenium oxide is thought to be improved. As the compound containing a carbonyl group, ketones, carboxylic acids, esters, amides, enones, acid chlorides, acid anhydrides, etc., which are highly stable against oxidizing agents, are preferable.

[0051] As described above, there are cases where the ligand is coordinated to ruthenium and cases where the ligand is reversely coordinated to ruthenium, but in the present application, both cases are considered to be ligands capable of coordinating with ruthenium. The ligand capable of coordinating with ruthenium may be added alone to the ruthenium oxide gas absorbing solution, or may be used in combination with an onium salt, which is the above-mentioned ruthenium oxide gas generation inhibitor.

[0052] When the ligand contains a hydrocarbon group, the number of carbon atoms in the hydrocarbon group is preferably 10 or less in order to maintain the solubility required for effective collection. When the ligand contains multiple hydrocarbon groups, the number of carbon atoms in each hydrocarbon group is preferably 10 or less. When the number of carbon atoms is large, the molecular weight increases, and the solubility of the ligand in the absorbing solution decreases. When the solubility decreases, the concentration of the ligand present in the absorbing solution decreases, and the collection effect of ruthenium oxide gas also decreases.

[0053] As described above in the mechanism of ruthenium oxide gas capture by the ligand, since O having a lone pair of electrons is coordinated to ruthenium in ruthenium oxide, it is preferable that the ligand contains a hydroxyl group and / or an ether bond.

[0054] For the reasons mentioned above, the ligands that can be suitably used in the present invention are Preferred are amines such as triethanolamine, nitrilotriacetic acid, ethylenediaminetetraacetic acid, glycine, and phthalic acid, thiols such as cysteine ​​and methionine, phosphines such as tributylphosphine and tetramethylenebis(diphenylphosphine), acetic acid, formic acid, lactic acid, glycolic acid, 2,2-bis(hydroxymethyl)propionic acid, gluconic acid, α-glucoheptonic acid, heptonic acid, phenylacetic acid, phenylglycolic acid, benzilic acid, gallic acid, cinnamic acid, naphthoic acid, anisic acid, salicylic acid, cresotic acid, acetylacetone ... Examples of the carbonyl compounds include monocarboxylic acids such as carboxylic acid, malic acid, and benzoic acid; dicarboxylic acids such as malic acid, adipic acid, succinic acid, maleic acid, tartaric acid, oxalic acid, dimethyl oxalate, glutaric acid, malonic acid, 1,3-adamantanedicarboxylic acid, and diglycolic acid; tricarboxylic acids such as citric acid; tetracarboxylic acids such as butane-1,2,3,4-tetracarboxylic acid; hexacarboxylic acids such as 1,2,3,4,5,6-cyclohexanehexacarboxylic acid; and carbonyl compounds such as ethyl acetoacetate and dimethylmalonic acid. More preferred are monocarboxylic acids such as acetic acid, formic acid, lactic acid, glycolic acid, 2,2-bis(hydroxymethyl)propionic acid, gluconic acid, α-glucoheptonic acid, heptonic acid, phenylacetic acid, phenylglycolic acid, benzilic acid, gallic acid, cinnamic acid, naphthoic acid, anisic acid, salicylic acid, cresotic acid, acrylic acid, and benzoic acid; dicarboxylic acids such as malic acid, adipic acid, succinic acid, maleic acid, tartaric acid, oxalic acid, dimethyl oxalate, glutaric acid, malonic acid, 1,3-adamantanedicarboxylic acid, and diglycolic acid; tricarboxylic acids such as citric acid; tetracarboxylic acids such as butane-1,2,3,4-tetracarboxylic acid; hexacarboxylic acids such as 1,2,3,4,5,6-cyclohexanehexacarboxylic acid; carbonyl compounds such as ethyl acetoacetate and dimethylmalonic acid; More preferred examples include oxalic acid, dimethyl oxalate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, succinic acid, acetic acid, butane-1,2,3,4-tetracarboxylic acid, dimethylmalonic acid, glutaric acid, diglycolic acid, citric acid, malonic acid, 1,3-adamantanedicarboxylic acid, and 2,2-bis(hydroxymethyl)propionic acid.

[0055] The concentration of the ligand in the ruthenium oxide gas absorbing solution is preferably 0.0001 to 60% by mass. If the amount of the ligand added is too small, not only the interaction with ruthenium oxide is weakened, reducing the effect of collecting ruthenium oxide gas, but also the amount of ruthenium oxide that can be dissolved in the absorbing solution is reduced, resulting in a decrease in analytical sensitivity. On the other hand, if the amount added is too large, a precipitate consisting of the ligand and ruthenium oxide is likely to be generated, and it causes interference with ICP-MS, making quantitative analysis difficult. Therefore, the absorbing solution of the present invention preferably contains 0.0001 to 60% by mass of the ligand, more preferably 0.01 to 35% by mass, and even more preferably 0.1 to 20% by mass. When adding a ligand, only one type may be added, or two or more types may be added in combination. Even if two or more types of ligands are included, ruthenium oxide gas can be effectively collected as long as the total concentration of the ligands is within the above concentration range.

[0056] By including these ligands in the absorbing solution, the amount of the absorbing solution can be reduced. Alternatively, by adding an onium salt other than hydroxide to the absorbing solution in addition to the ligand, the amount of the absorbing solution can be further reduced. Therefore, by including a ruthenium oxide gas generation inhibitor, it is possible to lower the lower limit of ruthenium oxide determination.

[0057] The onium hydroxide may also contain an organic alkali compound other than the onium hydroxide and / or ammonia. The organic alkali compound is a compound having carbon atoms and exhibiting alkalinity, and is preferably (a) a hydrocarbon amine compound having 3 or more carbon atoms, or (b) an amine compound containing an oxygen atom or a sulfur atom. Here, the amine compound is a compound containing a primary amine, a secondary amine, a tertiary amine, or a salt thereof. This also includes a carbamoyl group and a salt thereof.

[0058] The hydrocarbon group of the hydrocarbylamine compound (a) may be an alkane residue (typically an alkyl group, but may also be a divalent or higher group), an alkene residue, an aryl residue, or a combination thereof, such as cyclohexylamine, pentylamine, benzylamine, n-hexylamine, 2-ethylhexylamine, or octylamine.

[0059] The amine compound (b) having an oxygen atom or a sulfur atom is preferably a compound having a hydrocarbon group defined above and a substituent containing an oxygen atom or a sulfur atom. Specific examples include a hydroxyl group (OH), a carboxyl group (COOH), a mercapto group (sulfanyl group (SH)), an ether group (O), a thioether group (S), and a carbonyl group (CO). The amine compound (b) has one or more carbon atoms.

[0060] Specific examples of the amine compound (b) having an oxygen atom or a sulfur atom include methyl carbazate, O-methylhydroxylamine, N-methylhydroxylamine, monoethanolamine, 3-ethoxypropylamine, diglycolamine, triethanolamine, diethanolamine, monoethanolamine, N-methylethanolamine, N,N-diethylmonoethanolamine, diethylhydroxylamine, isopropanolamine, diisopropanolamine, and 2-(methylamino)ethanol.

[0061] The solvent of the ruthenium oxide gas absorbing solution is usually water. The water contained in the treatment solution of the present invention is preferably water from which metal ions, organic impurities, particle particles, etc. have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and is particularly preferably pure water or ultrapure water. Such water can be obtained by a known method that is widely used in semiconductor manufacturing. (Organic solvent) As described above, in the present invention, the onium ion present in the ruthenium oxide gas absorbing solution is RuO 4 - etc., and form an ion pair with RuO 4 - By retaining RuO etc. in the absorption solution, 4 The gas collection efficiency is improved. In this case, RuO 4 - Onium ions such as RuO are dissolved in solution in the form of ion pairs, but when the solubility is exceeded, they form a precipitate, RuO 4 This causes errors in quantitative gas analysis. Therefore, it is important to prevent the formation of such precipitates, and it is preferable to increase the solubility of the ion pair. Addition of an organic solvent is effective for this purpose. In addition, when a chemical species consisting of ruthenium oxide and a ligand capable of coordinating with ruthenium oxide forms a precipitate, the above-mentioned onium ion and RuO 4 - As in the case of ion pairs consisting of RuO4 and RuO5, it is possible to increase the solubility of the chemical species by adding an organic solvent to the ruthenium oxide gas absorbing solution, thereby reducing errors in the quantitative analysis of RuO4 gas. 4 - The effect of the organic solvent will be explained using the example of forming an ion pair with ruthenium oxide and the like, but when a chemical species consisting of ruthenium oxide and a ligand is formed, the ion pair in the following explanation can be read as a chemical species consisting of ruthenium oxide and a ligand.

[0062] In general, the lower the dielectric constant of a solvent, the easier it is to dissolve electrically neutral chemical species. Electrically neutral ion pairs are also more easily dissolved when the dielectric constant of the solvent is low. Therefore, in order to increase the solubility of ion pairs, it is desirable to add an organic solvent having a lower dielectric constant than water (dielectric constant 78) to the ruthenium oxide gas absorbing solution of the present invention. In this way, the dielectric constant of the ruthenium oxide gas absorbing solution can be reduced compared to the case of water alone, and the onium ion and RuO 4 - The solubility of the ion pair with the solvent, etc. can be increased, and the precipitation of the ion pair can be suppressed. Any organic solvent may be added as long as it has a lower dielectric constant than water, but the relative dielectric constant is preferably 45 or less, more preferably 20 or less, and even more preferably 10 or less. These relative dielectric constants are values ​​at 25°C.

[0063] Examples of such organic solvents include alkylnitriles, aldehydes, ethers, esters, ketones, sulfolanes, halogenated alkanes, and alcohols.

[0064] More specifically, 1,4-dioxane (dielectric constant 2.2), carbon tetrachloride (dielectric constant 2.2), benzene (dielectric constant 2.3), toluene (dielectric constant 2.4), propionic acid (dielectric constant 3.4), trichloroethylene (dielectric constant 3.4), diethyl ether (dielectric constant 4.3), chloroform (dielectric constant 4.9), acetic acid (dielectric constant 6.2), methyl benzoate (dielectric constant 6.6), methyl formate (dielectric constant 8.5), phenol (dielectric constant 9.8), p-cresol (dielectric constant 9.9), isobutyl alcohol (dielectric constant 17.9), acetone (dielectric constant 20.7), nitroethane (dielectric constant 28.1), acetonitrile (dielectric constant 37), ethylene glycol (dielectric constant 37.7), sulfolane (dielectric constant 43), etc., but of course, the organic solvent is not limited to these.

[0065] When an organic solvent with a low dielectric constant is added, it may be difficult to mix with water, but even in such a case, it is possible to increase the solubility of the ion pair by dissolving a small amount of the organic solvent in water, and the addition of the organic solvent is effective in suppressing the formation of precipitates.

[0066] The organic solvent may be added in an amount necessary to suppress the formation of precipitates. Therefore, the concentration of the organic solvent in the ruthenium oxide gas absorbing solution may be 0.1 mass % or more. However, it is necessary to increase the amount of dissolved ion pairs and to increase the RuO 4 - In order to stably retain the ruthenium oxide gas absorbent as an ion pair, the concentration of the organic solvent is preferably 1% by mass or more. 4 - As long as the amount of organic solvent added is within a range that does not impair the solubility of the onium salt or the stability of the ruthenium oxide gas absorbing solution, the amount of ion pairs that can be dissolved in the ruthenium oxide gas absorbing solution increases, so that not only can the formation of precipitates be suppressed, but also RuO 4 It is possible to prevent a decrease in gas collection efficiency. The organic solvent to be added may be one type, or a combination of two or more types may be added.

[0067] When a highly volatile organic solvent is used as the organic solvent, the organic solvent in the ruthenium oxide gas absorbing solution evaporates, changing the concentration of the organic solvent, changing the relative dielectric constant of the ruthenium oxide gas absorbing solution, and changing the solubility of the ion pair. Therefore, from the viewpoint of measurement stability, it is preferable to use an organic solvent with low volatility. Specifically, an organic solvent with a vapor pressure of 50 mmHg or less at 20°C is preferable, and an organic solvent with a vapor pressure of 20 mmHg or less is more preferable.

[0068] (Other additives) The ruthenium oxide gas absorbing solution of the present invention may contain other additives as desired within the scope of the present invention. For example, as other additives, acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidizing agents, reducing agents, complexing agents, chelating agents, surfactants, antifoaming agents, pH adjusters, stabilizers, etc. may be added. These additives may be added alone or in combination.

[0069] Due to these additives and for reasons of convenience in manufacturing the treatment liquid, the treatment liquid of the present invention may contain alkali metal ions such as sodium ions and potassium ions, alkaline earth metal ions such as calcium ions, etc. Therefore, for example, as a pH adjuster, alkali metal hydroxides such as sodium hydroxide and alkaline earth metal hydroxides may be contained. However, since these alkali metal ions and alkaline earth metal ions may affect quantitative analysis, it is preferable that the amount of them is small, and in fact it is better that they are not contained at all.

[0070] Specifically, the total amount of alkali metal ions and alkaline earth metal ions is preferably 1 mass% or less, more preferably 0.7 mass% or less, even more preferably 0.3 mass% or less, particularly preferably 10 ppm or less, and most preferably 500 ppb or less. (Method of analysis of ruthenium oxide) A method for analyzing ruthenium oxide in a gas to be treated according to an embodiment of the present invention involves contacting the gas to be treated containing ruthenium oxide gas with the above-described ruthenium oxide gas absorbing solution to recover ruthenium oxide gas from the gas to be treated, and then analyzing the amount of ruthenium oxide in the ruthenium oxide gas absorbing solution.

[0071] The gas to be treated is a gas containing ruthenium oxide, and is preferably derived from a semiconductor chemical used in processing a semiconductor material containing ruthenium metal. For example, it is ruthenium oxide gas generated when processing a substrate made of a semiconductor (e.g., Si) on which ruthenium wiring is formed. In addition, gas containing ruthenium oxide gas generated in an etching process, a residue removal process, a cleaning process, a CMP process, etc. in a semiconductor manufacturing process is also preferably used.

[0072] The ruthenium source to which the ruthenium oxide gas absorbing solution of the present invention is applied may be formed by any method. For the formation of a ruthenium film, methods widely known in the semiconductor manufacturing process, such as CVD, ALD, sputtering, plating, etc., may be used. The ruthenium may be metal ruthenium, ruthenium oxide, alloy with other metals, intermetallic compound, ionic compound, or complex. In addition, ruthenium may be exposed on the surface of the wafer, or may be covered with other metals, metal oxide film, insulating film, resist, etc. Even if covered with other materials, ruthenium oxide gas is generated when ruthenium dissolves during the processing process.

[0073] The amount of ruthenium oxide in the ruthenium oxide gas absorbing solution from which the ruthenium oxide gas has been recovered is analyzed by a known analytical method. The analytical method is not particularly limited, but for example, as an analytical method for radioactive ruthenium, it is possible to adopt a method in which ruthenium is separated by magnesium hydroxide coprecipitation-distillation or carbon tetrachloride extraction, and then reduced to precipitate ruthenium and quantify it. The amount of ruthenium oxide in the ruthenium oxide gas absorbing solution can also be quantified by ultraviolet-visible spectroscopy (UV-VIS). Furthermore, atomic absorption spectrometry and inductively coupled plasma optical emission spectroscopy can also be used as an analytical means, and in particular, in terms of simplicity and accuracy, analytical means using ICP optical emission spectroscopy (ICP-OES) and ICP mass spectrometry (ICP-MS) are preferred. Since the present invention has a high collection efficiency of ruthenium oxide, there is no need to concentrate the absorbing solution, and since an organic alkali is used, it is also possible to perform high-sensitivity analysis by ICP-MS.

[0074] In the ruthenium oxide gas absorbing solution of the present invention, the balance between ruthenium oxide capture efficiency and detection efficiency can be adjusted by adjusting the types of cations and anions, and the hydrocarbon chain length and concentration that constitute the organic alkali and the ruthenium oxide gas generation inhibitor. In addition, by using an organic alkali, the lower limit of quantification of ruthenium oxide gas can be reduced to about 1 / 500 to 1 / 1000 compared to when an inorganic alkali (such as NaOH or KOH) is used, and further, by adding a ruthenium oxide gas generation inhibitor to the absorbing solution, the amount of liquid during analysis can be reduced to about 1 / 2 to 1 / 5. This allows for about 2 to 5 times higher sensitivity.

[0075] Furthermore, by combining an organic alkali and a ruthenium oxide gas generation inhibitor, it is possible to lower the detection limit to a maximum of approximately 1 / 5000. In addition, the absorbing liquid containing the organic alkali containing an onium salt used in the present invention has both the effect of absorbing ruthenium oxide gas as an alkali and the effect of suppressing the generation of ruthenium oxide gas, making it suitable as an absorbing liquid for ruthenium oxide gas.

[0076] One embodiment of the trap device using such an absorbing liquid is as follows: An example of such a trap device is one which is disposed in an exhaust path in a processing step of a semiconductor device containing ruthenium metal, and which has a trap section for recovering a ruthenium oxide component in exhaust gas, and which is provided in the trap section with a container for charging the ruthenium oxide gas absorbing solution, a supply means, and a drain pipe for discharging the ruthenium oxide gas absorbing solution after absorption, as means for capturing ruthenium oxide contained in the exhaust gas.

[0077] One embodiment of an analytical apparatus using a trap device includes a quantitative analytical apparatus for ruthenium oxide gas, which is provided with a trap section that is disposed in an exhaust path in a processing step of a semiconductor device containing ruthenium metal and that recovers a ruthenium oxide component in an exhaust gas, and the trap section is provided with a container for the ruthenium oxide gas absorbing solution, a supply means, and a drain pipe for discharging the ruthenium oxide gas absorbing solution after absorption, as a means for capturing ruthenium oxide contained in the exhaust gas, and an analytical means for quantitatively analyzing the ruthenium oxide component in the absorbing solution drained from the trap device.

[0078] As the analytical means, the above-mentioned means can be used, and in particular, analytical means using ICP-OES, ICP-MS or UV-VIS are preferred because they are simple and highly accurate. [Example] The present invention will be specifically described below using examples, but the present invention is not limited to these examples in any way. Preparation of absorption solution The following ruthenium oxide gas absorbing solutions 1 to 10 were prepared. (1) Ruthenium oxide gas absorbing solution 1 (Example 1) As the organic alkali, an aqueous solution of tetramethylammonium hydroxide (TMAH) with a concentration of 1 mol / L was prepared. (2) Ruthenium oxide gas absorbing solution 2 (Example 2) As an organic alkali, 1.0 x 10 -3 A tetramethylammonium hydroxide (TMAH) aqueous solution with a concentration of 1 mol / L was prepared. (3) Ruthenium oxide gas absorbing solution 3 (Example 3) As the organic alkali, an aqueous solution of tetramethylammonium hydroxide (TMAH) with a concentration of 2 mol / L was prepared. (4) Ruthenium oxide gas absorbing solution 4 (Example 4) As the organic alkali, an aqueous solution of tetramethylammonium hydroxide (TMAH) with a concentration of 1 mol / L was prepared. (5) Ruthenium oxide gas absorbing solution 5 (Example 5) As an organic alkali, an aqueous solution of tetramethylammonium hydroxide with a concentration of 1 mol / L was prepared, and tetrapropylammonium chloride (TPACl) was added thereto so as to have a concentration of 5 mass %, thereby preparing a ruthenium oxide gas absorbing solution 5. (6) Ruthenium oxide gas absorbing solution 6 (Example 6) As the organic alkali, an aqueous solution of tetrapropylammonium hydroxide (TPAH) with a concentration of 1 mol / L was prepared. (7) Ruthenium oxide gas absorbing solution 7 (Example 7) An aqueous solution of tetramethylammonium hydroxide having a concentration of 1 mol / L and containing 5% by mass of malonic acid was prepared. (8) Ruthenium oxide gas absorbing solution 8 (Example 8) An aqueous solution of tetramethylammonium hydroxide having a concentration of 1 mol / L and containing 5% by mass of citric acid was prepared. (9) Ruthenium oxide gas absorbing solution 9 (Example 9) An aqueous solution of tetramethylammonium hydroxide having a concentration of 1 mol / L containing 5% by mass of citric acid and 5% by mass of tetrapropylammonium chloride was prepared. (10) Ruthenium oxide gas absorbing solution 10 (Comparative Example 1) As the alkaline aqueous solution, a sodium hydroxide aqueous solution with a concentration of 1 mol / L was prepared. <Examples 1 to 9 and Comparative Example 1> Testing Method: (1) 10 ml of a 2% by mass aqueous solution of sodium hypochlorite was placed in a sealed glass container with a volume of 85 ml, and the pH was adjusted to 12 with sodium hydroxide. Then, a silicon wafer with ruthenium deposited by sputtering (5 × 5 mm, Ru film thickness 20 nm; Ru amount 5.4 × 10 -8 mol) was immersed at 23° C. for 15 minutes. In Examples 4 to 9, the Ru film thickness was 5 nm (Ru amount was 1.35×10 -8 The unit mass was calculated as (mol).

[0079] It was confirmed by measuring the Ru film thickness using XRF that all of the Ru on the wafer had dissolved. (2) After that, nitrogen gas was flowed into the sealed container at 300 ml / min for 15 minutes, and the ruthenium oxide gas generated during the immersion of the ruthenium-coated silicon wafer was absorbed in gas trapping solution 1 and gas trapping solution 2, successively, according to the schematic diagram in Figure 1.

[0080] The same ruthenium oxide gas absorbing solution was used for gas trapping solutions 1 and 2, and the ruthenium oxide gas absorbing solutions 1 to 10 described above were used as the absorbing solution amounts shown in Table 1 for evaluation. (3) 10 ml of each of gas trap solution 1 and gas trap solution 2 was taken, and 20 ml of hydrochloric acid and ultrapure water were added to make the total volume 100 ml, and the solution was left to stand for 24 hours. These were used as the measurement solutions. (4) The measurement solution was measured using ICP-OES (Thermo Fisher iCAP6500Duo, measurement wavelength 240.2 nm) to quantify Ru. (5) The measurement solution was measured by ICP-MS (ICP-MS7900, manufactured by Agilent Technologies, Ru detection m / z=101) to quantify Ru. (6) Since no Ru was detected in gas trap solution 2 by either ICP-OES or ICP-MS, the amount of Ru absorbed in gas trap solution 1 was used as the quantitative value of ruthenium oxide.

[0081] In Examples 1 to 9 and Comparative Example 1, the gas trapping solution 2 was used to perform the measurement 10 times under the same conditions, and the standard deviation (σ) of the measured values ​​was calculated. The lower limit of quantification was the minimum amount that could be quantified as an analytical value, and was set to 10 times σ. The results are shown in Table 1.

[0082] [Table 1] Comparative Example 1 could not be evaluated by ICP-MS because it contained a large amount of sodium. The lower limit of quantification for ICP-OES was 1.4 × 10 -8 It was a mole.

[0083] As shown in Examples 1 to 3, it was found that the amount of ruthenium oxide contained in the absorbing solution can be quantified with high sensitivity even when the concentration of hydroxide ions contained in the absorbing solution was changed. In Example 4, the ruthenium film thickness was half that of Example 1, so that the concentration of ruthenium contained in the absorbing solution was reduced, and the measurement value of ruthenium by ICP-MS was below the lower limit of quantification. In Examples 5 and 6, the amount of absorbing solution could be reduced by containing tetrapropylammonium ions, which have a ruthenium trapping effect, in the absorbing solution. In addition, in Examples 7 and 8, the amount of absorbing solution could be reduced by containing malonic acid and citric acid, which have a ruthenium trapping effect, in the absorbing solution as ligands. In Example 9, the amount of absorbing solution could be further reduced compared to Examples 7 and 8 by adding an onium salt other than hydroxide in addition to the ligand to the absorbing solution. As a result, in Examples 5 to 9, the lower limit of quantification of ruthenium oxide could be lowered compared to Example 4, so that ruthenium oxide could be quantified with high sensitivity by ICP-MS.

[0084] From the above results, the present invention achieved a 1000-fold increase in sensitivity in the quantitative determination of ruthenium oxide. In addition, because the amount of the absorption solution can be reduced, high sensitivity is possible without the need for operations such as concentration, which was effective in both ICP-MS and ICP-OES.

Claims

1. The organic alkaline solution contains an onium salt having an ammonium ion as an onium ion and an anion at least part of which is a hydroxide ion, and the hydroxide ion concentration is 1×10 -7 A ruthenium oxide gas absorbing solution having a concentration in the range of more than 6 mol / L and not more than 6 mol / L.

2. 2. The ruthenium oxide gas absorbing solution according to claim 1, wherein the ammonium ion is a tetraalkylammonium ion.

3. 3. The ruthenium oxide gas absorbing solution according to claim 2, wherein the tetraalkylammonium ion is at least one kind of tetraalkylammonium ion selected from the group consisting of tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetrabutylammonium ion.

4. 2. The ruthenium oxide gas absorbing solution according to claim 1, further comprising an onium salt composed of an onium ion and an anion other than hydroxide as a ruthenium oxide gas generation inhibitor.

5. 5. The ruthenium oxide gas absorbing solution according to claim 4, wherein the onium ion is a quaternary onium ion represented by formula (1) or a tertiary onium ion represented by formula (2). 【Chemistry 1】 【Chemistry 2】 (In formula (1), A + is an ammonium ion or a phosphonium ion, and R 1 , R 2 , R 3 , R 4 is 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, where R 1 , R 2 , R 3 , R 4 When R is an alkyl group or an allyl group, 1 , R 2 , R 3 , R 4 At least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine. + is a sulfonium ion, R 1 , R 2 , R 3 is an alkyl group having 1 to 25 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 25 carbon atoms, or an aryl group. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen atom may be replaced by fluorine or chlorine.

6. The onium ion is represented by formula (1), and R 1 , R 2 , R 3 , R 4 The ruthenium oxide gas absorbing solution according to claim 5, wherein is a quaternary onium ion which is an alkyl group having 1 to 4 carbon atoms.

7. The ruthenium oxide gas absorbing solution according to claim 4, wherein the anion is at least one selected from the group consisting of a fluoride ion, a chloride ion, an iodide 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, and a trifluoroacetate ion.

8. The ruthenium oxide gas absorbing solution according to any one of claims 1 to 7, further comprising a ligand capable of coordinating with ruthenium as a ruthenium oxide gas generation inhibitor.

9. The ruthenium oxide gas absorbing solution according to claim 8, wherein the ligand coordinated with the ruthenium is oxalic acid, dimethyl oxalate, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, succinic acid, acetic acid, butane-1,2,3,4-tetracarboxylic acid, dimethylmalonic acid, glutaric acid, diglycolic acid, citric acid, malonic acid, 1,3-adamantanedicarboxylic acid, or 2,2-bis(hydroxymethyl)propionic acid.

10. The concentration of the onium ion is 1×10 -7 2. The ruthenium oxide gas absorbing solution according to claim 1, wherein the ruthenium oxide gas absorbing solution has a concentration of 1.0 mol / L to 8 mol / L.

11. The ruthenium oxide gas absorbing solution according to claim 1, further comprising water or an organic solvent.

12. 12. The ruthenium oxide gas absorbing solution according to claim 11, wherein the organic solvent has a relative dielectric constant of 45 or less.

13. The ruthenium oxide gas absorbing solution according to claim 11 or 12, characterized in that the organic solvent is at least one selected from the group consisting of sulfolanes, alkylnitriles, halogenated alkanes, ethers, esters, aldehydes, ketones, and alcohols.

14. The ruthenium oxide gas absorbing solution according to claim 11, characterized in that the concentration of the organic solvent in the treatment solution is 0.1 mass % or more.

15. A method for analyzing ruthenium oxide in a gas to be treated, comprising contacting the gas to be treated containing ruthenium oxide gas with the ruthenium oxide gas absorbing solution according to claim 1 to recover ruthenium oxide gas from the gas to be treated, and then analyzing the amount of ruthenium oxide in the ruthenium oxide gas absorbing solution.

16. 16. The analytical method according to claim 15, wherein the gas to be treated originates from a chemical for semiconductors used in processing a semiconductor material containing ruthenium metal.

17. 1. A trap device, which is disposed in an exhaust path in a processing step of a semiconductor device containing ruthenium metal, and which comprises a trap section for recovering a ruthenium oxide component in an exhaust gas, and which is provided in the trap section with a container for charging the ruthenium oxide gas absorbing solution according to claim 1 as a means for capturing ruthenium oxide contained in the exhaust gas, a supply means, and a drain pipe for discharging the ruthenium oxide gas absorbing solution after absorption.

18. A trap device, which is disposed in an exhaust path in a processing step of a semiconductor device containing ruthenium metal, and which has a trap section for recovering a ruthenium oxide component in an exhaust gas, the trap section comprising a container for receiving the ruthenium oxide gas absorbing solution according to claim 1 as a means for capturing ruthenium oxide contained in the exhaust gas, a supply means, and a drain pipe for discharging the ruthenium oxide gas absorbing solution after absorption; The apparatus for quantitatively analyzing ruthenium oxide gas comprises an analyzing means for quantitatively analyzing the ruthenium oxide component in the absorbing liquid discharged from the trap device.

19. 19. The quantitative analysis apparatus according to claim 18, wherein the analysis means is an analysis means using ICP optical emission spectrometry, ICP mass spectrometry, or ultraviolet-visible spectrometry (UV-VIS).

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