JP2011242401A - Column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply and precisely evaluating a pollution state in a gas without using an absorbing solution when a pollutant in the gas is sampled.SOLUTION: A gas adsorbing column includes a column which is filled with a filler prepared by holding an adsorbent on a base material with an average particle size or cross-sectional average diameter of 500-1000 μm and keeps a void volume of 5-100 μl. The adsorbent is preferably a base substance or an acid substance.

Description

  The present invention relates to a gas adsorption column containing an acid substance or a base substance.

  In an environment for manufacturing an electronic substrate (hereinafter referred to as a substrate) such as a semiconductor wafer, a liquid crystal substrate, and a magnetic disk, contaminants such as acid substances and base substances in the manufacturing space are adsorbed on the substrate, Since the yield of products and the quality are lowered, the process of manufacturing such a substrate is performed in a clean room. In addition, it is necessary to evaluate the contamination state due to the above-mentioned acid substances, base substances, etc. in the clean room in each manufacturing process. For example, as the technique, air in the clean room sucked by a suction pump is flowed at a constant flow rate. In this method, the pollutant in the air is absorbed and the absorbed pollutant is analyzed, or the air in the clean room sucked by the suction pump is passed through the filter at a constant flow rate. A method of adsorbing contaminants, desorbing contaminants from a filter with a solvent, and analyzing the desorbed contaminants has been proposed (see, for example, Non-Patent Documents 1 and 2 and Patent Document 1).

  In recent years, a clean room has been required to secure a more sophisticated cleaning space, and accordingly, a method for evaluating a contamination state due to an acid or a base with higher sensitivity is required.

“Appendix 1 Method for Measuring Acidic Substances in Cleanrooms and Related Control Environment Air”, JACA No. 35A-2003 Air Cleanliness Notation and Measurement Method Guidelines for Molecular Contaminants in Cleanrooms and Related Control Environments, Japan Air Cleaners Association, March 1, 2003, p. 5-6 “Appendix 2 Method for Measuring Basic Substances in Cleanroom and Related Control Environment Air”, JACA No. 35A-2003 Air Cleanliness Notation and Measurement Method Guidelines for Molecular Contaminants in Cleanrooms and Related Control Environments, Japan Air Cleaners Association, March 1, 2003, p. 7-9 JP 2003-2222577 A

  However, in the conventional method for evaluating the state of contamination of gas, when the concentration of pollutants in the air is low, the analysis is performed by concentrating the absorbing solution, etc., but the concentrated solution is subjected to the total amount analysis, It was difficult to subject the pollutant absorbed in the absorbing solution to the total amount analysis, which was not satisfactory from the viewpoint of high sensitivity evaluation. Further, in the evaluation method using the absorbing solution, there is a possibility of contamination of the clean room by the absorbing solution.

  Under such circumstances, as a result of intensive investigations to meet the above-mentioned problems, a specific column is used to adsorb pollutants such as acid substances and base substances in the air, and the pollutants adsorbed on the column are solvent-solved online. By extracting and analyzing, the present inventors have found that the contamination state can be evaluated easily and accurately without using an absorbing solution when sampling contaminants in the air, and the present invention has been completed.

  That is, the present invention is a column in which a base material having an average particle diameter or a cross-sectional average diameter of 500 μm to 1000 μm is packed with a filler in which an adsorbent is held, and the void volume of the column is 5 to 100 μl. It is applied to the gas adsorption column.

  Further, the present invention allows the gas to be evaluated to pass through the column so that the acid substance or base substance contained in the gas is adsorbed to the filler in the column, and the adsorbed acid substance or base substance is respectively adsorbed. The present invention relates to a method for evaluating the contamination state of a gas that is analyzed by extracting a solvent online.

  In the present invention, the gas to be evaluated is passed through the column so that the acid substance contained in the gas is adsorbed to the packing material in the column, and the adsorbed acid substance is subjected to solvent extraction online for analysis. This is a method for evaluating the state of gas contamination.

  In the present invention, the gas to be evaluated is passed through the column so that the basic substance contained in the gas is adsorbed to the packing material in the column, and the adsorbed basic substance is subjected to solvent extraction online for analysis. This is a method for evaluating the state of gas contamination.

  According to the present invention, the state of gas contamination by acid substances and base substances can be evaluated with high sensitivity, and can be evaluated without using an absorbing solution.

  The column of the present invention is a column filled with a filler in which an adsorbent is held on a base material.

  Examples of the material for the substrate include glass, quartz, polycarbonate resin, polystyrene resin, polyamide resin, and the like. Preferably, it is glass or quartz.

  The shape of the substrate is preferably a shape having a large surface area, and examples thereof include particles and fibers. Preferably, it is particulate.

  The average particle diameter of the substrate or the average cross-sectional diameter of the substrate is preferably 500 μm or more, and more preferably 600 μm or more, from the viewpoint of increasing the ventilation efficiency. Moreover, from a viewpoint of improving collection efficiency, Preferably it is 1000 micrometers or less, More preferably, it is 850 micrometers or less. The measurement method at this time is based on JIS K0069 “Chemical product screening test method”.

  As the adsorbent, a basic substance or an acid substance is used.

  Examples of the basic substance used as the adsorbent include inorganic bases and organic bases. Examples of the inorganic base include alkali metal carbonates and alkali metal hydroxides, and examples of the organic base include amines and ammonium compounds.

  The basic substance used as the adsorbent is preferably at least one compound selected from the group consisting of alkali metal carbonates, alkali metal hydroxides, amines and ammonium compounds.

  Examples of the alkali metal carbonate include sodium carbonate, potassium carbonate, potassium hydrogen carbonate and the like. Examples of the alkali metal hydroxide include strontium hydroxide, potassium hydroxide, and sodium hydroxide. Examples of the amine include triethanolamine. Examples of the ammonium compound include tetramethylammonium hydroxide and tetrabutylammonium hydroxide.

  More preferably, the basic substance used as the adsorbent is at least one compound selected from the group consisting of sodium carbonate, sodium hydroxide and triethanolamine.

  Examples of the acid substance used as the adsorbent include inorganic acids and organic acids.

  Examples of the inorganic acid include sulfuric acid and phosphoric acid. Examples of the organic acid include methanesulfonic acid, maleic acid, malonic acid and the like.

  The acid substance used as the adsorbent is preferably at least one compound selected from the group consisting of sulfuric acid, phosphoric acid and methanesulfonic acid.

  As a method for holding the adsorbent on the substrate, when the adsorbent is a solid substance, dissolve it in a solvent to form a solution, and apply the solution to the substrate, or apply the solution to the substrate. In the case where the adsorbent is a liquid substance, the solution is dissolved in a solvent to form a solution and the solution is applied to the substrate, or the substrate is immersed. And a method of drying the solvent.

  In addition to the adsorbent, a humectant may be applied to the substrate. Examples of the humectant include polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin; polyalkylene glycols such as polyethylene glycol and polypropylene glycol.

  The column is preferably made of a material that does not affect the analysis of the acid substance / base substance to be analyzed, and has a pressure resistance that can withstand a pressure of about 10 MPa. As the material of the column, stainless steel, polyether ether ketone resin or the like is usually used. In addition, the column shape is usually a cylindrical shape, preferably a column body, a frit, a sleeve, and an end fitting, such as those described in JP-A-2001-249120. Can give.

  The column volume can be appropriately sized according to the analytical throughput. The column volume is usually 0.1 ml to 0.5 ml, preferably 0.2 ml to 0.3 ml.

  The void volume of the column after packing with the packing material is 5 μl to 100 μl. If the void volume is too small, the gas aeration rate to the column will be low, and if the aeration pump is used to vent the suction pump, The load may be high. In addition, if the void volume is too large, the separation column of the measuring apparatus may be deteriorated by drying due to bubbles generated from the column during online extraction. The void volume of the column is preferably 10 μl to 50 μl. Note that the volume of the part to which the pipe is connected is, for example, in the case of a column comprising a column body, frit, sleeve and end fitting, the internal thread provided in the end fitting or the column body for connection to the pipe. The volume of the part is not included.

  In the evaluation method of the present invention, when evaluating the amount of the gas acid substance or base substance to be evaluated, by passing the gas to be evaluated through the column, the acid substance or base substance contained in the gas to be evaluated Is adsorbed by the packing material in the column. Aeration is usually performed using a suction pump. The aeration rate is preferably 0.1 to 2 L / min. The aeration time is preferably several minutes to 24 hours.

  The gas to be evaluated is passed through the column in a space to be evaluated such as a clean room or a clean booth. The column is transported by sealing the opening of the column with a stopper free of contamination of the analysis target substance and / or storing it in a sealed container free of contamination of the analysis target substance.

  The column after the gas to be evaluated is vented is connected to a measuring device, and by online solvent extraction, contaminants are extracted from the packing material. Evaluate. Here, online solvent extraction means that the column after the gas to be evaluated is vented and the analytical column are connected in series in the same line, for example, a pump that sends the extract to the analytical column By connecting the column after the gas to be evaluated is passed between the gas and the analytical column, the extract flows into the column, and the extract containing the contaminant extracted by the extract is analyzed. Refers to the form introduced in

  The analysis of the extract is usually carried out by liquid chromatography, using an anion exchange method using an ion exchange column, a cation exchange method, a suppressor method ion chromatography method using a suppressor, or an ODS column. Examples include reverse phase chromatography.

  As an apparatus for performing solvent extraction online and sending the entire amount of the extract to the measuring apparatus, an apparatus having a configuration shown in FIG. 1 having a liquid feed pump and a four-way valve can be given. The apparatus without the gas adsorption column connected has the configuration shown in FIG. The four-way valve is switched from the configuration of FIG. 2 to connect the gas adsorption column to the apparatus, and the configuration shown in FIG. 3 is obtained. At the time of measurement, the four-way valve is switched to the configuration shown in FIG.

  Examples of the acid substance to be analyzed include hydrogen chloride, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, formic acid, acetic acid and the like, as well as ammonium fluoride, ammonium formate, ammonium acetate, and the like. In addition, examples of the base substance to be analyzed include bases such as ammonia, trimethylamine, triethylamine, and alkanolamine, as well as ammonium fluoride, ammonium formate, and ammonium acetate.

  Clean rooms and clean booths can be listed as evaluation target spaces. In addition, EFEM (Equipment Front End Module), FOUP (Front Opening Unified Pod), SMIF (Standard Mechanical Interface) pod, etc., which are defined in SEMI (Semiconductor Equipment and Materials International) standard, can also be mentioned.

  The invention is explained in more detail by means of examples.

Example 1
(Preparation of gas adsorption column)
Particulate quartz sand having a particle size of 600 to 850 μm was packed in a stainless steel column having an internal volume of 0.27 ml, and ultrapure water was passed through the column to wash the inside of the column. Next, a mixed aqueous solution of sulfuric acid and glycerin was passed through the inside of the column, nitrogen was passed through to dry the solvent, and a gas adsorption column was obtained. The void volume of this gas adsorption column was 45 μl.

(Evaluation of laboratory contamination)
A gas suction pump was connected to the gas adsorption column, and air in the laboratory was passed through the gas adsorption column at a suction speed of 0.5 L / min for 1 hour. Next, the gas adsorption column was connected to an ion chromatograph, the ammonium adsorbed on the adsorbent in the gas adsorption column was solvent-extracted online, and the amount of ammonium ions deposited was measured by ion chromatography. The analysis results are shown in Table 1.

Example 2
(Evaluation of clean booth contamination)
A gas suction pump was connected to the gas adsorption column prepared in the same manner as in Example 1, and the air in the clean booth installed in the laboratory was vented to the gas adsorption column at a suction speed of 0.5 L / min for 24 hours. . Next, the gas adsorption column was connected to an ion chromatograph, the ammonium adsorbed on the adsorbent in the gas adsorption column was solvent-extracted online, and the amount of ammonium ions deposited was measured by ion chromatography. The analysis results are shown in Table 1.

It is the schematic of the apparatus at the time of performing solvent extraction on-line and analyzing an extract. It is the schematic of the apparatus with which the column for gas adsorption is not connected. It is the schematic of the apparatus at the time of connecting the column for gas adsorption to an analyzer.

1: Eluent 2: Pump 3: Four-way valve 4: Separation column 5: Gas adsorption column

Claims (4)

  A column in which a base material having an average particle diameter or a cross-sectional average diameter of 500 μm to 1000 μm is packed with a filler in which an adsorbent is held, and the void volume of the column is 5 to 100 μl. Gas adsorption column.   The column according to claim 1, wherein the adsorbent is a basic substance.   The column according to claim 2, wherein the basic substance is at least one compound selected from the group consisting of an alkali metal carbonate, an alkali metal hydroxide, an amine, and an ammonium compound.   The column according to claim 1, wherein the adsorbent is an acid substance.

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