JPH1164316A - Method for analyzing air in clean room for organic gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which the air in a clean room can be analyzed quickly with high sensitivity for organic gases which may cause air contamination and the organic gases can be evaluated collectively. SOLUTION: In a method for analyzing air in clean room for organic gas, a sample collected by combining an adsorbent collecting method and a thermally attaching and detaching method is qualitatively analyzed with a gas- chromatograph massspectrometer (GC-MS) and the chromatograph detected by the gas chromatograph is classified into hydrocarbons, halogenated hydrocarbons, oxygen-containing compounds, and siloxanes. Then the hydrocarbons, halogenated hydrocarbons, compounds, and siloxanes are determined by respectively using four kinds of standard reference materials, for example, toluene, fluorine-based solvent, 2-propenyloxybenzene, decamethylcyclopentasiloxane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for analyzing organic gas present in clean room air for manufacturing semiconductors.

[0002]

2. Description of the Related Art In recent years, even in the semiconductor industry, precision equipment industry, pharmaceutical industry, food industry, and the like, for high quality products, controlling air pollutants affecting products and creating a clean manufacturing environment. Maintaining a clean room is essential. In the clean room, the main types of air pollutants to be controlled are fine particles (metal particles, inorganic salts), inorganic gases (SOX, NOX, ammonia), and organic gases (hydrocarbons, siloxanes). Can be

As a recent technology for controlling contamination in a clean room, the development of a high-performance particle removal filter has made it possible to remove particulate contaminants to a considerable extent. On the other hand, control of gas pollutants has become a new problem. In order to reduce chemical pollutants, in the construction of clean rooms, evaluation methods for selecting construction materials are being developed.

Gas pollutants are roughly classified into organic gases and inorganic gases containing ionic components. There are not so many types of inorganic gases, and analytical methods are relatively well established.
Inorganic gas collection methods are roughly classified into two methods, a solution absorption method and a filtration collection method, and the analysis method is an inductively coupled plasma quadrupole mass spectrometer (ICP-MS) or a flameless atomic absorption method. (FLASS) and ion chromatography, and there are four analytical methods in combination.

[0005]

The organic gases that may be present in the clean room include hydrocarbons and halogenated hydrocarbons from the outside air, organic solvents used in the production of products, and amines generated from the human body. And siloxanes,
In addition, there is an extremely large variety of substances, such as substances volatilized from manufacturing line equipment and building materials for clean rooms. There is no clear standard for them (such as upper limits of harm or limits).

[0006] Therefore, the usual analysis is performed by a combination of a collecting method and an analyzer according to the target organic matter. For example, as a collecting method, a direct collecting method,
There are a solution absorption method, an adsorbent collection method, and the like, and the analysis methods include gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), and liquid chromatography (IC). HPLC), absorption spectrophotometry and the like.

[0007] It is very important in the production process of a product to clarify what kind of organic matter is present in a clean room and to what extent. Would take a very long time. Therefore, conventionally, to obtain the result in a particularly short time,
For example, only the components considered to be important from the viewpoint of the degree of adverse effects on products are identified and analyzed in advance.

The present invention has been made in view of the above points, and an object of the present invention is to provide an analysis method capable of quickly and accurately quantifying an organic gas in a clean room.

[0009]

In order to solve the above-mentioned problems, the present invention relates to a method for analyzing an organic gas in clean room air, wherein a chromatogram by a gas chromatograph is used for analyzing hydrocarbons, halogenated hydrocarbons, and oxygen-containing compounds. , Classified into four types of siloxanes, 4 corresponding to each
It shall be quantified by calibrating with various kinds of standard substances.

By doing so, the total amount of the organic gas in the clean room air can be easily determined by calibrating with the standard substances corresponding to the four types. As the four kinds of standard substances corresponding to the four kinds of hydrocarbons, halogenated hydrocarbons, oxygen-containing compounds, and siloxanes, toluene, a fluorine-based solvent, 2-propenyloxybenzene, and decamethylcyclopentasiloxane are used. Shall be.

As will be described later in the embodiments, the correlation coefficient is large and accurate quantification is possible. As a method of collecting the analysis gas, the organic gas contained in the clean room air is collected by the adsorbent, thermally desorbed, and introduced into the analyzer. In the case of the adsorption and thermal desorption methods, it is possible to analyze a wide range of the sampling amount and a low concentration level.

Further, qualitative analysis is performed by a gas chromatograph mass spectrometer, and the organic gases contained in the clean room air are classified into the above four types. With a gas chromatograph mass spectrometer, qualitative analysis can be performed quickly and four types of classification can be easily performed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to achieve the above objects, the method of analyzing organic gas in clean room air according to the present invention is to classify organic gases into four types for each system and to use standard materials representative of each type. Is quantified. Hereinafter, embodiments of the present invention will be described based on examples with reference to the drawings.

FIG. 1 is a flowchart showing a procedure from gas sampling to analysis of organic gas in clean room air according to the present invention. As a gas sampling method, an adsorbent collection method was adopted, and as an analysis method, a gas chromatograph-mass spectrometer method (GC-MS) and a gas chromatograph method (GC) were adopted. Hereinafter, the analysis method of the present invention will be described in detail according to this procedure.

First, as a preparation stage for gas collection, the adsorption tube 1 used for gas sampling is subjected to sufficient heat aging and blank measurement, and is sealed and stored. Graphite carbon was used as an adsorbent, and aging was performed at 260 ° C. for 5 hours or more. FIG. 2 is an explanatory diagram of a sample air sampling device and a sampling method. After attaching the suction pipe 1 to the suction pump 2, the air in the clean room is sucked, and the contaminated gas is adsorbed on the suction pipe 1. At that time, the amount of air sucked (collected amount) by the integrating flow meter 3 is measured.

In this embodiment, 100 liters (hereinafter referred to as L) were collected. In sampling clean room air, the expected gas concentrations (ppm, ppb, pp
The sampling amount is appropriately determined according to t), and the suction pump 2 and the integrating flow meter 3 are selected. The sampling time is preferably measured a plurality of times in one day to obtain an average over the whole day. Table 1 shows a comparison between the adsorbent collection method of the present example and the direct collection method performed in general work environment measurement and the like.

[0017]

[Table 1] The direct collection method is a method in which gas is collected in a vacuum collection bottle or a sampling bag, and then introduced into an analyzer using a syringe or the like. It is necessary to analyze immediately after collection, the residence time until analysis has to be as short as possible, and there is a problem of analysis accuracy in that attention must be paid to changes in concentration. Since the amount collected is limited by the type of container,
Depending on the gas concentration, the lower limit of quantification may be worse than the evaluation level.

On the other hand, the adsorbent collection method has a wide range of collection amount, and can analyze even a concentration level (ppb to ppt) lower than the concentration level (ppm) by the direct collection method, and has high sensitivity. Thus, it can be said that this method is suitable for trace analysis. If it is necessary to store the sample, store it in a cooler box or freezer. Next, the gas-absorbed adsorption tube 1 is placed in a thermal desorption device 4, thermally desorbed, and analyzed in combination with the GC-MS 5 and GC.

FIG. 3 shows a thermal desorption apparatus and an analyzer (GC-M).
It is the schematic which shows the connection with S). The adsorption tube 1 is placed in a thermal desorption device 4 and heated. After being cooled and collected in a secondary trap tube 6 cooled with liquid nitrogen, the secondary trap tube 6 is heated (358 ° C.) and thermally desorbed. , GC-MS5. Helium was used as the carrier gas. The purpose of cooling and collecting the sample in the secondary trap tube 6 is to control the speed at which the sample is introduced into the GC-MS 5.

As the method of desorption after the organic gas is collected by the adsorbent, the thermal desorption method of the present embodiment and the solvent desorption method (method of dissolving in a solvent) carried out in the measurement of general working environment and the like.
Table 2 shows a comparison between the advantages and disadvantages.

[0021]

[Table 2] In the solvent desorption method, it is necessary to select the type of the adsorbent and the solvent, and depending on the concentration, further concentration work or the like is performed,
Care must be taken to account for the effects of contamination due to solvent purity. For this reason, the operation is somewhat complicated, lacks in quickness, and cannot be said to be an appropriate method for a wide range of gas analysis.

On the other hand, the thermal desorption method is advantageous in that it can analyze a wide range of components from low boiling components to high boiling components depending on the selection of the adsorbent. This can be done by setting, and the online system can be analyzed, so that quick analysis can be performed without complexity. A standard spectrum is searched based on the mass spectrum obtained by GC-MS5 to specify an organic gas component (qualitative analysis).

Next, the adsorption tube is thermally desorbed as in the case of GC-MS, and quantitative analysis is performed by gas chromatography (GC). At this time, the GC detector appropriately selects TCD (thermal conductivity detector), FID (flame ionization detector), FPD (flame light intensity detector), PID (photoionization detector), etc. according to the target component. However, in this example, the area for each gas component was determined using FID. The organic gases detected based on the results of the qualitative analysis are classified into four types: hydrocarbons, halogenated hydrocarbons, oxygen-containing compounds, and siloxanes, and quantified by a standard sample to determine the total gas amount. Determined (quantitative analysis). The classification into four types is for the purpose of promptly performing the work of quantification using a standard sample.

The standard samples representing the four types classified above include toluene as a hydrocarbon, a fluorinated solvent as a halogenated hydrocarbon, 2-propenyloxybenzene as an oxygen-containing compound, and decamethylcyclobenzene as a siloxane. Pentasiloxane was used. The calibration curve method is applied to these to determine the concentration in the air, which is converted for each component. The empirical formula at this time is shown in Table 3. S in the equation is the peak area.

[0025]

[Table 3]

Correlation coefficient r between gas component concentration and peak area
Is good from 0.994 to 0.999. Thus, the total amount of the organic gas classified into four types (ng / L)
Can be evaluated. In addition, chloroform may be used as the standard substance of the halogenated hydrocarbons.

FIG. 4 is a gas chromatogram obtained by analyzing 100 L of an organic gas in a clean room air sampled as a real sample. With respect to the numerical values in the chromatogram, the detected organic gas indicating the retention time and the classified type are shown in Table 4, and the results of the quantified four types of components are shown in Table 5.

[0028]

[Table 4]

[0029]

[Table 5]

As a result of analyzing the organic gas in the clean room of the actual sample, the total amount of the detected organic gas was 1362 n.
g / L. There was no significant difference between the total gas amount obtained by the four-class classification method of the present invention and the total gas amount obtained for all components without the four-class classification. That is, if the above classification is made,
Even if the calibration curve of the standard substance used in each classification is used, quantification can be performed without a large error.

When the detected organic gas excludes an organic solvent such as isopropyl alcohol used in the production of the product, it is 127 ng / L, which is a low level of contamination in a clean room. Table 6 shows a comparison between the four classification methods of the present invention and the case of analysis without classification.

[0032]

[Table 6] The detected gas components are diversified as shown in Table 4 and FIG. Without the four-class classification, it is necessary to obtain a standard sample for all detected individual components and perform quantification work, and the period until quantification becomes long, and rapid analysis cannot be performed. In the four classification methods, similar types of organic gases are put together, and a standard sample is selected and quantified, so that the quantification work can be greatly simplified and speeded up.

According to the above classification method, hydrocarbons and halogenated hydrocarbons from the outside air taken into the clean room, organic solvents used in the production of products, amines and siloxanes generated from human activities, and production lines In particular, the total amount of substances that evaporate from the equipment and building materials for clean rooms can be easily grasped. In particular, organic gas volatilized from equipment on a production line or a building material for a clean room can be analyzed following a change over time depending on a sampling time, and it can be said that it is extremely practical in product management.

[0034]

As described above, according to the present invention, in a method for analyzing an organic gas in clean room air, the organic gas is used in the form of hydrocarbons, halogenated hydrocarbons, oxygen-containing compounds, and siloxanes. By classifying them into types and quantifying them using representative standard substances such as toluene, fluorine-based solvents, 2-propenyloxybenzene, and decamethylcyclopentasiloxane, a comprehensive Evaluation enabled.

In particular, as a sampling method, an adsorbent collection method and a thermal desorption method are combined, and as a qualitative and quantitative analysis method, a gas chromatograph-mass spectrometer (GC-M
By combining S) and a gas chromatograph (GC), a wide range of gas components from low boiling components to high boiling components can be easily grasped. The organic gas analysis and evaluation method of the present invention is extremely effective in reducing organic pollutants in a clean room.

[Brief description of the drawings]

FIG. 1 is a flowchart of a procedure from gas sampling to analysis.

FIG. 2 is an explanatory diagram of a gas sampling method.

FIG. 3 is a schematic diagram of a GC-MS analyzer.

FIG. 4 Actual sample (contaminants in air collected in 100 L)
Gas chromatogram of

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adsorption tube 2 Suction pump 3 Integral flow meter 4 Desorption device 5 GC-MS 6 Secondary trap tube

Claims (4)

[Claims] In a method for analyzing organic gas in clean room air, a chromatogram detected by a gas chromatograph is classified into four types of hydrocarbons, halogenated hydrocarbons, oxygen-containing compounds, and siloxanes. A method for analyzing organic gas in clean room air, wherein the method is quantified by calibrating with four kinds of standard substances corresponding to the above. 2. Four kinds of standard substances corresponding to four kinds of hydrocarbons, halogenated hydrocarbons, oxygen-containing compounds and siloxanes, toluene, fluorine-based solvent, 2-propenyloxybenzene, decamethylcyclohexane The method for analyzing organic gas in clean room air according to claim 1, wherein pentasiloxane is used. 3. The method for analyzing organic gas in clean room air according to claim 1, wherein the organic gas contained in the clean room air is collected by an adsorbent, thermally desorbed and introduced into an analyzer. . 4. A qualitative analysis using a gas chromatograph mass spectrometer, and the organic gas contained in clean room air
The method for analyzing organic gas in clean room air according to claim 3, wherein the method is classified into species.