WO2006035609A1

WO2006035609A1 - Method for trace analysis and analyzer therefor

Info

Publication number: WO2006035609A1
Application number: PCT/JP2005/016979
Authority: WO
Inventors: Yuji Sakai; Hiromoto Ohno
Original assignee: Showa Denko K.K.
Priority date: 2004-09-30
Filing date: 2005-09-14
Publication date: 2006-04-06
Also published as: JP4699377B2; CN100458438C; CN101031794A; TW200624804A; KR100837477B1; KR20070058662A; JPWO2006035609A1

Abstract

[PROBLEMS] To provide a method for analyzing trace components contained in a mixed gas containing fluorine gas easily and simply with high precision and an analyzer therefor. [MEANS FOR SOLVING PROBLEMS] A method for trace analysis, characterized by reacting (i) a mixed gas which comprises fluorine gas and a diluent gas and contains trace components with (ii) a hydrogen-containing substance to convert the fluorine gas into hydrogen fluoride, removing the hydrogen fluoride through fixation, and then analyzing the trace components by gas chromatography; and an analyzer for trace components which comprises a reactor tube forreacting (i) a mixed gas which comprises fluorine gas and a diluent gas and contains trace components with (ii) a hydrogen-containing substance, a tube filled with an alkali metal fluoride, a gas sampler composed of a six-way changeover valve capable of changing the flow channel of a carrier gas and a sample measuring tube capable of preparing a certain amount of a sample that is connected to the valve, and a gas chromatograph and which is piped so that the mixed gas and the hydrogen-containing substance can flow in this order.

Description

Specification

Trace component analysis method and analyzer

Technical field

[0001] The present invention relates to a method for analyzing a trace component contained in a mixed gas containing fluorine gas. More specifically, the present invention comprises a fluorine gas and a diluent gas. The present invention relates to a method for easily and accurately analyzing carbon oxide, carbon dioxide, and other trace components, and an analyzer for the same.

Background art

[0002] Conventionally, as a method for analyzing trace components contained in fluorine gas, (1) a corrosion-resistant gas outlet that uses nickel, monel, fluorine resin, fluorine oil, or the like for the portion in contact with fluorine gas. (2) A method in which fluorine gas is passed through a metal fluoride packed bed to remove fixed ions as a high-order metal fluoride and then analyzed by gas chromatography (Japanese Patent Laid-Open No. 7-287001 (Patents) References 1)) are known. However, in the method (1), since the fluorine gas is directly introduced into the separation column, the usable filler is limited to a filler that does not react with fluorine, and in such a filler, fluorine gas and Since there is no suitable filler for separating other components such as oxygen, there is a problem that the components that cannot be separated cannot be analyzed. In the method (2), in the case of fluorine gas diluted with a rare gas or the like, there is a problem that fluorine is not completely fixed by the metal fluoride and fluorine gas remains.

Patent Document 1: Japanese Patent Laid-Open No. 7-287001

Disclosure of the invention

Problems to be solved by the invention

[0003] The present invention seeks to solve the problems associated with the prior art as described above, eliminates the disadvantages of the conventional methods, and contains a mixture containing fluorine that can be used as a special material gas for semiconductors. It is an object of the present invention to provide a method for simply and accurately analyzing a trace component contained in a gas and to provide an analyzer for the method.

Means for solving the problem [0004] As a result of intensive studies to solve the above problems, the present inventors have made fluorine gas by reacting a mixed gas containing a trace component and a hydrogen-containing substance, which is composed of a fluorine gas and a diluent gas. By using an analysis method characterized in that the hydrogen fluoride is converted to hydrogen fluoride and the hydrogen fluoride is removed and then analyzed, and a mixed gas containing hydrogen and a diluent gas and containing a trace component and hydrogen Gas sampler with a reaction tube for reacting contained substances, a tube filled with alkali metal fluoride, and a six-way switching valve capable of switching the carrier gas flow path connected to a sample metering tube capable of dispensing a certain amount of sample And a trace component analyzer having a gas chromatograph and piped so that the mixed gas and the hydrogen-containing substance flow in this order. Found that analysis of trace components contained in the mixed gas containing fluorine is possible, thereby completing the present invention.

[0005] The present invention relates to a method for analyzing a trace component contained in a mixed gas containing fluorine shown in the following [1] to [6] and an analyzer therefor.

[1] (i) a mixed gas comprising a fluorine gas and a diluent gas, containing a trace component, and

(ii) Hydrogen-containing substances

A method for analyzing a trace component, comprising: converting the fluorine gas into hydrogen fluoride, removing the fixed hydrogen fluoride, and then analyzing the trace component.

[0006] [2] The analysis method according to [1] above, wherein the temperature at which the mixed gas and the hydrogen-containing substance are reacted is in the range of 50 to 250 ° C.

[3] The analysis method according to [1] or [2] above, wherein the dilution gas is an inert gas.

[4] The hydrogen fluoride fixed layer removal uses a layer filled with an alkali metal fluoride.

V, The analysis method according to any one of [1] to [3] above.

[0007] [5] The concentration power of fluorine gas in the mixed gas is 30 vol% or less.

V, analysis method as described in somewhere.

[6] (i) a mixed gas comprising a fluorine gas and a diluent gas and containing a trace component, and (ii) a reaction tube for reacting a hydrogen-containing substance,

A tube filled with alkali metal fluoride,

A gas sampler with a sample metering tube connected to a hexagonal switching valve that can switch the carrier gas flow path, and a sample metering tube that can dispense a certain amount of sample, and Gas chromatograph

The trace gas analyzer is arranged such that the mixed gas and the hydrogen-containing material force flow in this order.

The invention's effect

[0008] According to the present invention, a fluorine gas and a diluent gas are used, and a mixed gas containing a trace component and a hydrogen-containing substance are reacted to convert the fluorine gas into hydrogen fluoride, thereby fixing and removing hydrogen fluoride. After the removal, analysis by gas chromatograph makes it possible to analyze the trace components contained in the mixed gas containing fluorine simply, accurately and efficiently.

Brief Description of Drawings

[0009] Fig. 1 is a diagram showing an analysis device for trace components in a mixed gas containing fluorine gas according to the present invention.

FIG. 2 is an enlarged view of the six-way switching valve 6 shown in FIG.

Explanation of symbols

[0010] 1-5 Banolev

6 Six-way switching valve

7 Container valve

8-9 mass flow controller

10 Sample container

11 Reaction tube for fluorine gas and hydrogen-containing material

12 Heating heater

13 Tube filled with alkali metal fluoride

14 Sample measuring tube

15 Flow rate 10

16 Gas chromatograph

BEST MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, an analysis method and an analysis apparatus according to the present invention will be described in detail.

In the analysis method of the present invention, it consists of a fluorine gas and a diluent gas, and contains trace components. The fluorine gas is converted to hydrogen fluoride by reacting the mixed gas and the hydrogen-containing substance, and the hydrogen fluoride is fixed and removed, and then analyzed by gas chromatography.

If a mixed gas consisting of fluorine gas and dilution gas is analyzed directly by gas chromatography, corrosion of the gas chromatograph and deterioration of the packing material of the separation column will occur and the analysis will not be possible with high accuracy. Need to be removed.

[0012] As the dilution gas, for example, helium (He), neon (Ne), argon (Ar), thalibutone (Kr), xenon (Xe), radon (Rn) and nitrogen (N) force are also selected. Including species

2

Inert gas. The concentration of fluorine gas in the mixed gas is preferably 30 vol% or less, more preferably 10 vol% or less. If it is 30 vol% or more, a large amount of heat is generated when the fluorine gas reacts with the hydrogen-containing substance, which may cause problems such as safety and corrosion.

[0013] In addition, as the hydrogen-containing substance, any substance that can react with fluorine gas and a substance by-produced by the reaction does not hinder the analysis of the trace component may be used, for example, hydrogen (H),

2 and hydrogen-containing compounds such as methane (CH), ethane (C H) and propane (C H).

4 2 6 3 8

Among these, hydrogen (H) is preferable.

2

Chemical changes when these hydrogen-containing substances react with fluorine, such as hydrogen (H).

2 When it is used, it can be expressed by the following equation.

[0014] F + H → 2HF · · · (1)

twenty two

As in the above reaction formula (1), the fluorine gas is replaced with hydrogen fluoride. In order to increase the efficiency of the reaction, it is desirable to react fluorine and a hydrogen-containing substance at a high temperature.

. For example, when the hydrogen-containing substance is hydrogen, the reaction is promoted even at room temperature, but it is preferable to set the temperature within the range of 50 to 250 ° C to complete the reaction! /.

[0015] The molar ratio of the hydrogen atom in the hydrogen-containing substance to the fluorine atom in the fluorine gas is preferably in the range of HZ F = 1 to 10! /.

In a reaction tube where fluorine gas reacts with hydrogen-containing substances, only fluorine gas and hydrogen-containing substances react and oxygen, nitrogen, carbon monoxide, carbon dioxide, and other gases, which are trace components contained in fluorine gas, are reacted. , And dilution gas passes through the tube without loss or increase. Nitrogen is not a minor component when used as a diluent gas. [0016] As a method for supplying a gas mixture containing a trace component and a gas composed of a fluorine gas and a dilution gas to a reaction tube, for example, a method of supplying each gas with a mass flow controller Is mentioned. In addition, it is preferable that the mixed gas containing the trace component and the hydrogen-containing substance are mixed in advance before the reaction tube. The gas containing hydrogen fluoride generated by the above reaction is introduced into a tube filled with an alkali metal fluoride, and the hydrogen fluoride is fixed and removed. The alkali metal fluoride used here may be any compound that can remove hydrogen fluoride in a fixed manner. For example, lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF ) And the like. The chemical change when hydrogen fluoride is introduced into a tube filled with an alkali metal fluoride, for example, when sodium fluoride (NaF) is used, is expressed as follows.

[0017] HF + NaF → NaF-HF (2)

As shown in the above reaction formula (2), hydrogen fluoride is removed in a fixed manner by an alkali metal fluoride such as sodium fluoride. In addition, since the above-described hydrogen fluoride fixation reaction is sufficiently promoted even at room temperature, the temperature of the tube filled with the alkali metal fluoride is not particularly limited. In the tube filled with the alkali metal fluoride, only hydrogen fluoride is removed, and oxygen, nitrogen, carbon monoxide, carbon dioxide, other gases, which are trace components contained in the mixed gas, and Dilution gas passes through the tube without loss or increase.

[0018] After the fluorine gas and hydrogen fluoride have been removed as described above, the mixed gas is introduced into a gas sampler equipped with a sample measuring tube. Here, the gas introduced into the gas sampler and weighed to a certain amount is guided to a gas chromatograph by a carrier gas such as helium (He), for example, by switching a six-way switching valve and filled with an appropriate filler. The trace component contained in the mixed gas is separated by the separation column.

For example, when a filler such as molecular sieve 5A is used in the separation column, oxygen, nitrogen, and carbon monoxide can be separated. At this time, although carbon dioxide is adsorbed, oxygen, nitrogen, carbon monoxide and carbon dioxide can be separated by using other fillers such as silica gel. In the present invention, a thermal conductivity detector can be used as a detector of the gas chromatograph. However, if it is desired to obtain higher sensitivity, a photoion detector that is particularly sensitive to inorganic gas can be used.

[0020] “Specific Analysis Methods and Analysis Ί

Next, the actual analysis method and analysis apparatus of the present invention will be described more specifically with reference to FIG. 1 showing the apparatus used for the analysis method of the present invention.

First, after connecting the sample container 10 filled with the mixed gas containing fluorine gas to the pipe, confirm that the container valve 7 is closed, open the valves 4 and 5, close the 2 and 3, and switch the hexagon Valve 6 is in the state of the solid line in FIG. 1, helium gas is circulated by the mass flow controller 8 from the pipe extending from valve 1, and a mixed gas containing fluorine gas and a pipe through which hydrogen gas circulates as a hydrogen-containing substance, for example, Helium is substituted for air components and other components that give positive errors in analysis.

Next, the valves 1, 4 and 5 are closed, the valve 3 and the sample container valve 7 are opened, and the mixed gas containing fluorine gas is circulated at a constant flow rate by the mass flow controller 8. At the same time, hydrogen gas is caused to flow at a constant flow rate from the pipe extending from valve 2 by the mass flow controller 9. At this time, the flow rate of hydrogen gas per unit time should be such that the molar ratio is equal to or greater than the flow rate of fluorine gas per unit time. The mixed gas and hydrogen gas containing fluorine gas are guided to the reaction tube 11 of fluorine gas and hydrogen gas heated by the heater 12 and exhausted from the valve 3 until a steady state is reached.

[0022] After confirming that the fluorine gas has been completely converted to hydrogen fluoride, the valve 3 is closed, the valves 4 and 5 are opened, and the outlet gas of the reaction tube 11 is connected to the tube 13 filled with alkali metal fluoride. Then, hydrogen fluoride is removed with an alkali metal fluoride such as sodium fluoride.

Thereafter, the sample gas and unreacted hydrogen gas are exhausted through the sample measuring tube 14 and the flow meter 15. Next, after closing the valve 5 and confirming that the gas flow has stopped by the flow meter 15, the flow path is switched to the dotted line in FIG. By this operation, a certain amount of sample gas and unreacted hydrogen gas introduced into the sample measuring tube are entrained by the carrier gas and introduced into the gas outlet matrix 16. Sample gas introduced into gas chromatograph 16 and unreacted Hydrogen gas is separated by a column packed with a gas chromatograph packing material and detected by a thermal conductivity detector. By comparing the peak area of the standard gas analyzed in advance with the same procedure and the peak area of the trace component of the sample gas, the concentration of the trace component can be determined.

[0023] [Example]

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples.

The sample gas was prepared by filling the sample container with fluorine gas generated by the fluorine generator FG (made by Showa Denko KK), and then further filling with neon (Ne) gas so that the fluorine concentration would be 3 vol%. .

[0024] The sample gas and the hydrogen gas are respectively supplied by a mass flow controller so that the hydrogen gas has a molar ratio twice that of the fluorine gas in the sample gas, and a reaction tube for the fluorine gas and the hydrogen-containing substance. These were mixed at the inlet, and introduced into a reaction tube heated to 150 ° C. with a heater. The reaction tube outlet gas was absorbed in potassium iodide (KI) aqueous solution, titrated with sodium thiosulfate aqueous solution and analyzed for unreacted fluorine gas.The fluorine gas concentration was less than Ivolppm, and the fluorine gas was almost completely removed. I reacted.

[0025] Next, after introducing the outlet gas of the reaction tube into a tube filled with sodium fluoride (NaF) as an alkali metal fluoride, the outlet gas was added to an aqueous potassium iodide (KI) solution. (KIO) is absorbed into the prepared aqueous solution and titrated with an aqueous sodium thiosulfate solution.

Three

When hydrogen fluoride was analyzed, the concentration of hydrogen fluoride was less than Ivolppm, and the hydrogen fluoride was removed.

[0026] Subsequently, the outlet gas of the tube filled with sodium fluoride (NaF) was introduced into a gas sampler with a sample measuring tube. By switching the flow path in the gas sampler with the hexagonal switching valve, a certain amount of sample gas introduced into the sample metering tube is guided to the gas chromatograph by helium (He) as a carrier gas and filled in the gas chromatograph. The resultant was separated with molecular sieve 5A and silica gel. When analyzed with a thermal conductivity detector, the oxygen concentration was less than 2 volppm, the nitrogen concentration was less than 2 volppm, and the carbon dioxide concentration was less than Ivolppm. Industrial applicability

The present invention relates to a method for analyzing trace components contained in a mixed gas containing fluorine gas in a simple and accurate manner and an analyzer therefor. Such an analysis method and analysis apparatus of the present invention are useful for analyzing trace components contained in a mixed gas containing fluorine gas used as a special material gas for semiconductors, for example.

Claims

The scope of the claims

[1] (A mixed gas consisting of a fluorine gas and a diluent gas, containing trace components, and

(ii) Hydrogen-containing substances

After the reaction, the fluorine gas is converted into hydrogen fluoride, and the hydrogen fluoride is fixed and removed.

A method for analyzing a trace component, comprising analyzing the trace component.

[2] The analysis method according to claim 1, wherein the temperature at which the mixed gas and the hydrogen-containing substance are reacted is in the range of 50 to 250 ° C.

[3] The analysis method according to [1] or [2], wherein the dilution gas is an inert gas.

[4] The analysis method according to any one of [1] to [3], wherein the immobilization and removal of hydrogen fluoride is performed using a layer filled with an alkali metal fluoride.

[5] The analysis method according to any one of claims 1 to 4, wherein the concentration of fluorine gas in the mixed gas is 30 vol% or less.

A tube filled with alkali metal fluoride,

A gas sampler with a sample metering tube connected to a hexagonal switching valve that can switch the carrier gas flow path, and a sample metering tube that can dispense a certain amount of sample, and

Gas chromatograph