JP6062191B2 - Sampling method of sample gas - Google Patents

Description

  The present invention relates to a sampling method for sample gas, and more particularly, suppresses a change in concentration of an analyte in a sampled sample gas during a period from when the sample gas is sampled into a gas sampling bag to analysis. The present invention relates to a sample gas sampling method capable of improving accuracy.

  For example, in a detoxification device that performs detoxification treatment of toxic gas, the exhaust gas after the detoxification treatment is periodically analyzed to confirm that toxic components are reliably detoxified. When analyzing the exhaust gas from the detoxification device, the exhaust gas after the detoxification treatment is usually sampled in a gas container and conveyed to the analysis device. When the sample gas is sampled in the gas container, the gas composition may change due to reaction with components adsorbed on the inner surface of the container. For example, by chemically polishing the inner surface of the container, The gas composition in the gas container can be controlled by suppressing the change or by pressurizing and filling oxygen before sampling to react with the hydrogen present on the inner surface of the container and suppressing the release of hydrogen into the sampled sample gas. It has been attempted to suppress the change and improve the analysis accuracy (see, for example, Patent Documents 1 and 2).

JP 2004-354188 A JP 2000-171361 A

  Both of the analysis accuracy improving techniques described in both patent documents are directed to a metal gas container, and a sufficient effect can be expected for the metal gas container. On the other hand, in recent years, when sampling a sample gas, a sampling bag that is lighter and easier to handle than a metal gas container is often used. As the sampling bag for sampling the sample gas for analysis, a so-called aluminum bag is used, which is formed of a laminate film including an aluminum layer to provide a gas barrier property.

  However, in the aluminum bag, since various analytical accuracy improvement measures in the metal container described in both the above-mentioned patent documents can not be carried out, components that affect the composition of the sample gas are adsorbed on the bag inner surface, The component in the sample gas may be adsorbed. In particular, when analyzing an extremely small amount of component, such as several ppb, in the sample gas, when an aluminum bag purged with a normal nitrogen gas is used, it is enclosed in the aluminum bag. In some cases, the composition of the sample gas changed and accurate analysis could not be performed.

  Therefore, the present invention can suppress the variation in the composition of the sample gas when the sample gas is sampled using the gas sampling bag having the gas barrier property, that is, the aluminum bag, and improve the analysis accuracy of the component to be analyzed. It aims at providing the sampling method of the sample gas which can be performed.

To achieve the above object, a method of sampling a sample gas of the present invention is a method of sampling a sample gas containing an analyte component in a gas sampling bag having a gas barrier property, ,, the sample gas before sampling a sample gas A pretreatment is performed in which a pretreatment gas containing an analysis component that is 50 times or more of the concentration of the analysis component therein is introduced into the gas sampling bag.

Further, the sampling method of sample gas of the present invention, by performing the pre-Symbol pretreatment 24 hours or more, the a gas sampling bag, characterized by sealing the sample gas at a higher pressure than 3kPa than atmospheric pressure, also The component to be analyzed is a volatile metal hydride, which is exhaust gas discharged from a detoxifying device for detoxifying the volatile metal hydride.

  According to the sample gas sampling method of the present invention, before sampling the sample gas containing the component to be analyzed in the gas sampling bag, the pretreatment gas containing the component to be analyzed, preferably the concentration of the component to be analyzed in the sample gas is measured. A pretreatment gas that introduces a pretreatment gas containing a component to be analyzed 50 times or more, and is preaerated for a predetermined time or more, preferably 24 hours or more in the gas sampling bag, or is pretreated. As a result, the adsorption equilibrium of the analyte to be generated on the inner surface of the gas sampling bag can be stabilized by the analyte to be contained in the pretreatment gas.

  As a result, when the sample gas is introduced into the gas sampling bag after performing a normal purge operation after the pretreatment, for example, a normal purge operation with nitrogen gas, the analyte in the sample gas and the inner surface of the gas sampling bag Therefore, the gas sampling bag can be replaced with the sample gas with a small amount of sample gas. In addition, after the sample gas is introduced into the gas sampling bag, the concentration of the component to be analyzed does not change due to the adsorption equilibrium even if time elapses. Furthermore, by setting the sealing pressure of the sample gas in the gas sampling bag to a pressure 3 kPa or more higher than the atmospheric pressure, it is possible to prevent the analyte from desorbing from the inner surface of the gas sampling bag and to change the concentration of the analyte Can be prevented. In particular, when the component to be analyzed is a volatile metal hydride having strong adsorptivity, the concentration is reduced due to the adsorption of the volatile metal hydride on the inner surface of the gas sampling bag, and an accurate analysis is performed. Can do.

It is explanatory drawing of the gas sampling apparatus used in order to verify the sampling method of the sample gas of this invention. It is explanatory drawing of the gas analyzer used in order to verify the sampling method of the sample gas of this invention. It is a figure which shows the relationship between the composition of pre-processing gas when a to-be-analyzed component is monosilane, pre-processing gas circulation volume, and a measurement density | concentration. It is a figure which shows the relationship between the composition of pre-processing gas when a to-be-analyzed component is monosilane, pre-processing gas enclosure time, and a measurement density | concentration. It is a figure which shows the relationship between the sample gas enclosure time after pre-processing, when a to-be-analyzed component is monosilane, and a measurement density | concentration. It is a figure which shows the relationship between sample gas enclosure pressure and time, and a measurement density | concentration when a to-be-analyzed component is monosilane. It is a figure which shows the relationship between the composition of pre-processing gas when a to-be-analyzed component is a phosphine, pre-processing gas distribution volume, and a measurement density | concentration. It is a figure which shows the relationship between the composition of pre-processing gas when a to-be-analyzed component is a phosphine, pre-processing gas enclosure time, and a measurement density | concentration. It is a figure which shows the relationship between the sample gas enclosure time after pre-processing, when a to-be-analyzed component is a phosphine, and measured concentration. It is a figure which shows the relationship between the measurement density | concentration with the sample gas enclosure pressure and time after a pre-processing when a to-be-analyzed component is a phosphine. It is a figure which shows the relationship between the composition of pre-processing gas when a to-be-analyzed component is arsine, pre-processing gas distribution volume, and a measurement density | concentration. It is a figure which shows the relationship between the composition of pre-processing gas when a to-be-analyzed component is arsine, pre-processing gas enclosure time, and measured concentration. It is a figure which shows the relationship between the sample gas enclosure time after pre-processing when a to-be-analyzed component is arsine, and measured concentration. It is a figure which shows the relationship between the measurement density | concentration with the sample gas enclosure pressure and time after a pre-processing in case an analyzed component is arsine.

  The gas sampling bag having a gas barrier property used in the present invention is an aluminum bag formed of a laminate film including an aluminum layer as described above, and is formed on both surfaces of an aluminum foil (aluminum foil) constituting the aluminum layer. A commercially available aluminum bag formed of a laminate film in which nylon or nylon is laminated can be used. When the pretreatment gas or the sample gas is circulated in the bag, an aluminum bag having two gas distribution ports may be used. Moreover, although the enclosure volume of an aluminum bag is arbitrary, what is necessary is just to use the aluminum bag which usually has an enclosure volume of about 5 liters.

  Hereinafter, the present invention will be described in more detail on the basis of an example carried out using the gas sampling apparatus shown in FIG. 1 and the gas analyzer shown in FIG. As the sample gas, assuming the exhaust gas discharged from the abatement device of the semiconductor manufacturing facility and the atmosphere around the semiconductor manufacturing device, the monosilane having high reactivity and high adsorptivity used as the raw material gas for semiconductor manufacturing, Gases containing phosphine and arsine were used.

  The gas sampling device 11 shown in FIG. 1 connects a gas introduction path 13 to one sealing valve 12a of an aluminum bag (GLCL CCL-5: enclosed volume 5L) 12 and gas to the other sealing valve 12b. The derivation path 14 is connected. The gas inlet path 13 and the gas outlet path 14 are connected by a bypass path 15 having a bypass valve 15V, and are formed so that gas can flow from the gas inlet path 13 to the gas outlet path 14 without passing through the aluminum bag 12. ing.

  Connected to the gas introduction path 13 are a reference gas introduction path 16 for introducing a reference gas whose concentration is adjusted to a standard gas and a dilution gas introduction path 17 for introducing a dilution gas for diluting the reference gas. The reference gas introduction path 16 and the dilution gas introduction path 17 are provided with pressure control valves 16a and 17a and mass flow controllers 16b and 17b, respectively, and the dilution gas introduction path 17 has a bubbling tank (humidification) for allowing the dilution gas to flow into water. Tank) 18 is provided.

  A gas analyzer 21 shown in FIG. 2 includes a sample gas introduction path 22, a carrier gas introduction path 23, a plurality of switching valves 24, 25, and 26 connected to the gas lead-out path 14, and a measuring tube for measuring the sample gas. 27, a concentrating tube 28 for concentrating the component to be analyzed, a plurality of columns 31, 32, 33, 34, an analyzer 35, and an analyzer purge gas introduction path 36. A purification cylinder 22a filled with phosphorus pentoxide as a dehydrating agent is provided. The analyzer 21 analyzes the components to be analyzed which are measured by the measuring tube 27 and concentrated by the concentration tube 28 by switching the switching valves 24, 25 and 26 in a predetermined order and controlling the temperature of the concentration tube 28. It is formed so as to be analyzed by the vessel 35.

  As a standard gas, a gas containing 10 ppmv / v monosilane in nitrogen gas (volume ppm, the same applies hereinafter) is used, and an atmospheric component containing 20% oxygen volume in nitrogen gas and 500 ppmv / v carbon dioxide is used as a dilution gas. Used gas. The dilution gas was passed through the bubbling tank 17 so that the water was almost saturated. As the sample gas, a gas whose monosilane concentration was adjusted to 100 ppbv / v (volume ppb, the same applies hereinafter) by adjusting the flow rates of the standard gas and the dilution gas with the mass flow controllers 16b and 17b was used.

  The composition of the pretreatment gas used for the pretreatment of the aluminum bag is 100 times the concentration of monosilane in the sample gas (pretreatment gas A: 10 ppmv / v), 50 times (pretreatment gas B: 5 ppmv / v), 20 Nitrogen-containing nitrogen gas set to 10 times (pretreatment gas C: 2 ppmv / v) and 10 times (pretreatment gas D: 1 ppmv / v), respectively, and nitrogen that does not contain monosilane assuming a conventional purge method After using gas (pretreatment gas E) to circulate each pretreatment gas through the aluminum bag 12 and performing gas replacement, the sealing valves 12a and 12b are closed and the respective pretreatment gases A to E are sealed. It was allowed to stand for 6 hours, 12 hours, 24 hours and 48 hours. After standing for a predetermined time, nitrogen gas (the same gas as the pretreatment gas E) was circulated in each aluminum bag, and the aluminum bag in which the inside of each aluminum bag was sufficiently replaced with nitrogen was used as the sample gas sampling aluminum bag.

  An aluminum bag for sampling each sample gas is set in the gas sampling device, and the change in monosilane concentration analyzed by the analyzer while circulating the sample gas (monosilane concentration 100 ppbv / v) is applied to each pretreatment gas A to E. A record was made for each pretreated aluminum bag. The result is shown in FIG. Further, FIG. 4 shows the relationship between the pretreatment gases A to D sealed in each aluminum bag and the monosilane concentration analyzed by the analyzer. Further, in an aluminum bag subjected to pretreatment in which pretreatment gas B having a monosilane concentration of 50 times and pretreatment gas E not containing monosilane are sealed for 24 hours, the bag is sealed immediately after the monosilane concentration analyzed by the analyzer is stabilized. The stop valves 12a and 12b were respectively sealed and the sample gas was sealed in an aluminum bag. After 1 to 3 days had elapsed, the sample gas in each aluminum bag was analyzed by an analyzer. The result is shown in FIG. Moreover, the pressure of the sample gas sampled in the aluminum bag is set to 0 kPa (atmospheric pressure), 1 kPa, 2 kPa, 3 kPa, 5 kPa, and 10 kPa, respectively, 3 days, 1 week, and 2 weeks after sealing the sample gas. After 4 weeks, the sample gas in each aluminum bag was analyzed. The result is shown in FIG.

  The standard gas was replaced with the monosilane-containing nitrogen gas of Example 1, and a gas containing 10 ppmv / v of phosphine in the nitrogen gas was used, and the phosphine concentration in the sample gas was set to 30 ppbv / v. The same gas as in Example 1 was used as the dilution gas.

  The composition of the pretreatment gas used for the pretreatment of the aluminum bag is 100 times the phosphine concentration of the sample gas (pretreatment gas A: 3 ppmv / v), 50 times (pretreatment gas B: 1.5 ppmv / v) , Phosphine-containing nitrogen gas set to 20 times (pretreatment gas C: 0.6 ppmv / v) and 10 times (pretreatment gas D: 0.3 ppmv / v), respectively, and nitrogen gas containing no phosphine ( The pretreatment gas E) was used to circulate each pretreatment gas through the aluminum bag and perform gas replacement. Then, the sealing valves 12a and 12b were closed to enclose the pretreatment gases A to E, respectively, for 6 hours. It was allowed to stand for 12 hours, 24 hours and 48 hours. After standing for a predetermined time, the inside of each aluminum bag was replaced with nitrogen gas to obtain an aluminum bag for sample gas sampling.

  An aluminum bag for sampling each sample gas is set in the gas sampling device, and the change in the phosphine concentration analyzed by the analyzer while the sample gas (phosphine concentration 30 ppbv / v) is circulated in each pretreatment gas A to E. A record was made for each pretreated aluminum bag. The result is shown in FIG. Moreover, the relationship between the sealing time of the pretreatment gases A to D in each aluminum bag and the phosphine concentration analyzed by the analyzer is shown in FIG. Furthermore, in an aluminum bag subjected to pretreatment in which pretreatment gas B having a phosphine concentration of 50 times and pretreatment gas E not containing phosphine are sealed for 24 hours, sealing immediately after the phosphine concentration analyzed by the analyzer is stabilized. The stop valves 12a and 12b were respectively sealed and the sample gas was sealed in an aluminum bag. After 1 to 3 days had elapsed, the sample gas in each aluminum bag was analyzed by an analyzer. The result is shown in FIG. Moreover, the pressure of the sample gas sampled in the aluminum bag is set to 0 kPa (atmospheric pressure), 1 kPa, 2 kPa, 3 kPa, 5 kPa, and 10 kPa, respectively, 3 days, 1 week, and 2 weeks after sealing the sample gas. After 4 weeks, the sample gas in each aluminum bag was analyzed. The result is shown in FIG.

  The standard gas was replaced with the monosilane-containing nitrogen gas of Example 1, and a gas containing 1 ppm v / v of arsine in nitrogen gas was used. The arsine concentration in the sample gas was set to 5 ppbv / v. The same gas as in Example 1 was used as the dilution gas.

  The composition of the pretreatment gas used for the pretreatment of the aluminum bag is 100 times the pretreatment gas arsine concentration (pretreatment gas A: 500 ppbv / v), 50 times (pretreatment gas B: 250 ppbv / v), 20 Nitrogen gas (pretreatment gas E) not containing arsine is used while using arsine-containing nitrogen gas set to double (pretreatment gas C: 100 ppbv / v) and 10 times (pretreatment gas D: 50 ppbv / v). After each pretreatment gas was circulated through the aluminum bag and replaced with gas, the sealing valves 12a and 12b were closed and the pretreatment gases A to E were sealed, respectively, for 6 hours, 12 hours, 24 hours and Allowed to stand for 48 hours. After standing for a predetermined time, the inside of each aluminum bag was replaced with nitrogen gas to obtain an aluminum bag for sample gas sampling.

  An aluminum bag for each sample gas sampling is set in the gas sampling device, and the change in the arsine concentration analyzed by the analyzer while the sample gas (arsine concentration 5 ppbv / v) is circulated in each pretreatment gas A to E. A record was made for each pretreated aluminum bag. The result is shown in FIG. Further, FIG. 12 shows the relationship between the pretreatment gases A to D sealed in each aluminum bag and the arsine concentration analyzed by the analyzer. Further, in an aluminum bag subjected to pretreatment in which pretreatment gas B having arsine concentration of 50 times and pretreatment gas E not containing arsine are sealed for 24 hours, sealing is performed immediately after the arsine concentration analyzed by the analyzer is stabilized. The stop valves 12a and 12b were respectively sealed and the sample gas was sealed in an aluminum bag. After 1 to 3 days had passed, the sample gas in each aluminum bag was analyzed with an analyzer. The result is shown in FIG. In addition, the pressure of the sample gas sealed in the aluminum bag is set to 0 kPa (atmospheric pressure), 1 kPa, 2 kPa, 3 kPa, 5 kPa, and 10 kPa, respectively, 3 days, 1 week, and 2 weeks after the sample gas is sealed. After 4 weeks, the sample gas in each aluminum bag was analyzed. The result is shown in FIG.

  From each of the above examples, by performing the pretreatment using the pretreatment gas containing the component to be analyzed, the inside of the aluminum bag can be replaced with a small amount of sample gas when sampling is performed. It can be seen that the time required for sampling can be shortened. In particular, by using a pretreatment gas containing an analyte at a concentration 50 times or higher than the analyte concentration in the sample gas, the sample bag can be replaced with the sample gas with a smaller amount of the sample gas. Can do. There is no particular upper limit for the concentration of the analyte in the pretreatment gas, but if the analyte concentration is increased, the amount of analyte used increases, which is uneconomical. It is preferable to set to about 50 to 100 times.

  It can also be seen that the amount of sample gas during sampling can be reduced by bringing the inner surface of the aluminum bag into contact with the pretreatment gas for 24 hours or longer. There is no particular upper limit for the contact time, but if it is set to a long time, a large number of aluminum bags are required or management becomes troublesome. Therefore, it is usually preferable to perform pretreatment the day before sampling. .

  Furthermore, by increasing the pressure of the sample gas sealed in the gas sampling bag, the sample gas can be sealed in a stable state for a long time. The upper limit of the sealing pressure is limited by the pressure resistance of the aluminum bag, but may be set according to the pressure of the sample gas to be sampled.

  The operation for sampling the actual sample gas can be performed in the same manner as in the past, and the analyzer can be selected according to the type and concentration of the component to be analyzed.

  DESCRIPTION OF SYMBOLS 11 ... Gas sampling apparatus, 12 ... Aluminum bag, 12a, 12b ... Sealing valve, 13 ... Gas introduction route, 14 ... Gas extraction route, 15 ... Bypass route, 15V ... Bypass valve, 16 ... Reference gas introduction route, 17 ... Dilution gas introduction path, 16a, 17a ... pressure control valve, 16b, 17b ... mass flow controller, 18 ... bubbling tank, 21 ... gas analyzer, 22 ... sample gas introduction path, 22a ... purification cylinder, 23 ... carrier gas introduction path, 24, 25, 26 ... switching valve, 27 ... measuring tube, 28 ... concentrating tube, 31, 32, 33, 34 ... column, 35 ... analyzer, 36 ... purge gas introduction path for analyzer

Claims (5)

In a method for sampling a sample gas containing an analyte in a gas sampling bag having a gas barrier property, a pretreatment containing an analyte to be analyzed is 50 times or more the analyte concentration in the sample gas before sampling the sample gas A sample gas sampling method, wherein a pretreatment for introducing a gas into the gas sampling bag is performed. The pretreatment method of sampling a sample gas according to claim 1, wherein performing more than 24 hours. The sample gas sampling method according to claim 1 or 2 , wherein the sample gas is sealed in the gas sampling bag at a pressure 3 kPa or more higher than atmospheric pressure. The analyte component, a method of sampling a sample gas according to any one of claims 1 to 3 which is a volatile metal hydride. The sample gas, the sampling method of sample gas according to any one of claims 1 to 4 which is exhaust gas discharged volatile metal hydride from the abatement device for detoxification process.

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