JP2009175063A - Gas collector and method for evaluating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas collector capable of simply and sensitively evaluating and analyzing an inorganic system impurity component contained in an atmospheric gas in a clean room and a process gas used for a manufacturing process, and a method for evaluating and analyzing it. <P>SOLUTION: The gas collector includes a discharge electrode 13 for discharging in the midway of a tube that connects between an intake port 15 for a gas to be measured and an intake port 16 for an impinger. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention controls cleanliness of a clean room by managing inorganic impurity components contained in atmospheric gases and various process gases used in the manufacture of magnetic recording media and semiconductor wafers in a clean room production environment. The present invention relates to a gas collection device and its evaluation analysis method.

  Magnetic recording media, semiconductor wafers, manufacturing equipment, and manufacturing as the precision of magnetic recording media and the miniaturization of design patterns of semiconductor devices formed on semiconductor wafers and higher functionality that require manufacturing in a clean room There is an increasing demand for process cleaning. For example, inorganic impurities such as chlorine compounds, sulfides, nitric acid, and fluorine compounds contained in clean room atmosphere gases and various process gases used in magnetic recording medium manufacturing processes and semiconductor wafer processes are acidic. It is easy to become a substance. It is known that when these inorganic impurity components adhere to the surface of a semiconductor wafer or a manufacturing facility used in the process, the semiconductor characteristics are significantly deteriorated or corroded. Further, it is known that nitrogen oxide gas or sulfur oxide gas chemically reacts with ammonia or the like and precipitates as a salt, causing a pattern defect. There are similar problems with magnetic recording media. Therefore, the inorganic impurities contained in the atmospheric gas in the clean room and the process gases used in magnetic recording medium manufacturing processes and semiconductor wafer processes are collected and analyzed regularly, and the analysis results are as follows. Based on this, control of cleanliness in the production environment in a clean room by managing inorganic impurity components below a certain level is becoming increasingly important.

In the case of a semiconductor wafer process, the conventional flow of collecting and analyzing a gas containing an inorganic impurity component is as follows. In general, there is a collection step for collecting the sample, and then a method of performing an analysis step in which the collected solution containing the inorganic impurity component collected in the step is subjected to evaluation analysis by applying to each analyzer. In FIG. 8, the collection method and evaluation analysis method of various inorganic impurity components which have been already performed in the conventional collection step and the analysis step are summarized. As a collection method, in addition to collection by ion pin jar bubbling, silicon wafer collection, suction collection, adsorbent collection, and the like are known. As an evaluation analysis method, ion chromatography analysis, ion chromatography mass spectrometry, inductively coupled plasma emission spectrometry, inductively coupled plasma emission mass spectrometry, atmospheric pressure ionization mass spectrometry, or the like is used. Hereinafter, these conventional methods for collecting inorganic impurity components and evaluation analysis methods will be described in detail.
FIG. 2 and FIG. 3 show a first collection method and a collection apparatus for inorganic impurity components contained in an atmosphere gas or a process gas used in a manufacturing process in a clean room. In the first collection method and collection apparatus, a collection solution 4 such as pure water or dilute acid is put into an impinger 3, and the atmosphere gas 1 and the process gas 5 in the clean room are sucked by the suction pump 2. 3 is configured to be sucked into the collection solution 4 and bubbled into the collection solution 4. In this way, the inorganic impurity components contained in the suction gas are collected in the collection solution 4 made of pure water or dilute acid, and analyzed and evaluated by an ion chromatography method.

4 and 5 show a second collection method and a collection device for inorganic impurity components contained in the atmosphere gas and the process gas used in the manufacturing process in the clean room. In this second collection method and collection apparatus, an inorganic impurity component contained in a suction gas is obtained by installing a silicon wafer 6 or a magnetic recording medium standing on a mounting table 7 in a clean room or a process gas pipeline. Is collected on a silicon wafer 6 or a magnetic recording medium, subsequently extracted with water, and analyzed and evaluated by an ion chromatography method. It is also preferable to evaluate and analyze the inorganic impurity component by a method using atomic absorption or inductively coupled plasma emission spectrometer or inductively coupled plasma mass spectrometry after hydrofluoric acid vapor separation.
FIGS. 6 and 7 show a third method and apparatus for collecting inorganic impurity components contained in an atmosphere gas or a process gas used in a manufacturing process in a clean room. This third collection method and collection apparatus includes a hollow collection container 9 made of resin, glass, metal, or the like, or a collection container 9 filled with an adsorbent 10 such as zeolite, colloidal silica, or activated carbon. It has a structure in which the atmospheric gas 1 and the process gas 5 in the production environment are directly taken into a hollow collection container 9 or passed through a granular or filter-shaped adsorbent 10 for collection. Alternatively, an inorganic impurity component collected by sending the suction gas taken into the hollow collection container to an impinger (not shown) and bubbling the collection solution can be collected by, for example, an ion chromatography analyzer or an atmospheric pressure ionization mass spectrometer. An evaluation analysis method for analyzing and evaluating, and a collecting device. 6 and 7, reference numeral 2 is a suction pump, and reference numeral 8 is an open / close valve.

On the other hand, the following known techniques are known as methods for evaluating and analyzing impurity components contained in such a gas. By providing an air introduction unit to obtain the atmosphere from which moisture has been removed from the atmosphere to be evaluated and analyzed in the previous stage of the atmospheric pressure ionization mass spectrometer, it is possible to avoid generation of moisture-derived ions as noise. An analyzer that enables highly accurate measurement of trace impurities is disclosed (Patent Document 1).
Except for the gas discharge inlet, it has two series-arranged containers that have a sealed structure, and has a structure in which a pump is disposed on the downstream side of the latter container. The water is accommodated up to about 1/4 to 3/4, and the upper part of the collection solution becomes a flow space for the introduced gas. When the pump is operated, the gas flows into the container and the ammonia in the gas is captured. A gas collection device collected in a collection solution has been announced (Patent Document 2).
The ion composition of various cations and various anions that constitute basic, acidic, and organic fine particles, gaseous, and molecular chemical contaminants present in clean room air is highly soluble or dissociative. Capturing chemical contaminants in the air that are collected with high sensitivity and high accuracy by performing dissolution and dissociation reactions in the collection solution in the first collection container and the second collection container sequentially from the strong salt composition. A collecting method is also known (Patent Document 3).
JP-A-6-281539 (Summary) Japanese Patent Laid-Open No. 11-117977 (summary) JP 2003-302317 A (summary)

However, the above prior art has the following drawbacks. In the bubbling method using the impinger, which is the first collection method and the collection device described above, atmospheric gas, process gas, etc. are flowed into the collection solution such as pure water at a constant flow rate and time, Although the inorganic impurity component is absorbed, the solubility in pure water varies depending on the inorganic impurity component. For example, with respect to the solubility of sulfur dioxide, hydrogen sulfide is 1/10 or less, sulfur hexafluoride is 1/5000 or less, and nitrogen dioxide is 1/50, and the inorganic impurity component dissolved in the collection solution is the original. It is a problem that the content ratio of the inorganic impurity component in the atmospheric gas or process gas is not necessarily reflected.
In the second collection method and collection apparatus for adsorbing an inorganic impurity component on a silicon wafer, the surface impurity state of the semiconductor wafer such as a silicon wafer, for example, the presence or absence of an oxide film and the thickness of the oxide film, the inorganic impurity component There is a difference in the degree of adsorption. Therefore, when collecting the inorganic impurity components, it is necessary to provide a silicon wafer cleaning step and an oxide film generation step in order to make the surface state of the silicon wafer uniform. In addition, when acid or alkali is forcibly applied to the surface of a silicon wafer, for example, after extracting inorganic impurities adsorbed on the silicon wafer by a water extraction method, for example, ion chromatography, atomic absorption or inductively coupled plasma emission spectroscopy analyzer Alternatively, when measurement is performed with an inductively coupled plasma mass spectrometer or the like, the applied acid or alkaline substance may interfere with the detection lower limit level.

In the third collection method and collection apparatus described above, the amount of inorganic impurity components contained in the atmospheric gas and process gas in the production environment is as low as ppb to ppt (1/10 ⁹ to 1/10 ¹² ) level or less. Is the way. When the content level of such inorganic impurity components is low, the level of impurity elution from the collection container becomes a problem. In order to lower the elution level, it is necessary to perform aging of the collection container for a long time, and the efficiency is poor. Also in the method using an adsorbent, it is necessary to collect all adsorbents suitable for each adsorption for the inorganic impurity component to be collected. In addition, after collection, for example, ion chromatography, atomic absorption, inductively coupled plasma optical emission spectrometer or inductively coupled plasma mass spectrometer, and associated inorganic impurity extraction work can be performed for each adsorbent. It is difficult to say a simple collection and analysis method.
Further, as described in Patent Documents 1 to 3, a method for collecting and analyzing various different inorganic impurity components has been proposed, but it is used in an atmospheric gas in a manufacturing environment in a clean room or in a manufacturing process. There is no analysis method that can easily and sensitively evaluate and analyze inorganic impurity components in the process gas.
The present invention has been made in view of the above points, and an object of the present invention is to evaluate and analyze inorganic impurities contained in an atmosphere gas and a process gas used in a manufacturing process in a clean room. It is to provide a gas collection device and an evaluation analysis method thereof that can perform the measurement easily and with high sensitivity.

According to the first aspect of the present invention, the object of the present invention is provided with a discharge electrode that generates a discharge in the middle of a tube connecting the suction port of the measurement gas and the suction port of the impinger. This is achieved by using a gas collecting device.
According to the invention of claim 2, the discharge electrode has a corona, a creeping surface, and a needle-like tip capable of emitting a short-circuit discharge, and a direct current of 1000 V to 10000 V, an alternating current or a pulsed direct current, The gas collection device according to claim 1, which is connected to a power source capable of applying a pulsed alternating voltage.
According to the invention described in claim 3, the measurement gas is sucked and brought into contact with the discharge space where discharge is generated, and then bubbled into the collection solution in the impinger, and the measurement gas is discharged from the discharge port. And a gas evaluation and analysis method in which the cleanliness of the gas is detected by a gas analyzer.
According to the invention described in claim 4, the measurement gas is an atmospheric gas or a gas used for a process in manufacturing a semiconductor or a magnetic recording medium. Claim 3 The gas evaluation analysis according to claim 3 The method.

  ADVANTAGE OF THE INVENTION According to this invention, the gas collection apparatus which can perform the evaluation analysis of the inorganic type impurity component contained in the atmospheric gas in a clean room, and the process gas used by a manufacturing process simply with sufficient sensitivity, and its evaluation An analysis method can be provided.

Hereinafter, a gas collection device and an evaluation analysis method thereof according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the description of the examples described below unless it exceeds the gist.
FIG. 1 is a flowchart of a method for collecting and analyzing an inorganic impurity component contained in an atmospheric gas and a process gas according to the present invention. FIG. 9 is a schematic cross-sectional view of a trapping device using an impinger added with a discharge process when the measurement target gas is an atmospheric gas according to the present invention. FIG. 10 is a bar graph showing the measurement result of the inorganic impurity ion component in the atmospheric gas in the clean room according to the present invention. FIG. 11 is a schematic cross-sectional view of a collection device using an impinger to which a discharge process is added when the measurement target gas is a process gas according to the present invention. FIG. 12 is a bar graph showing measurement results of nitrogen impurity and inorganic impurity ion components in the air according to the present invention.
Examples of the inorganic impurity components collected by the gas collection method and collection device according to the present invention include acidic components such as fluorine compounds, chlorine compounds, nitrogen compounds, bromine compounds, phosphorus compounds, and sulfides. . In order to efficiently collect these inorganic impurity components using an absorption solution, for example, pure water, the inorganic impurity components are respectively fluorine ions, chlorine ions, and nitrate ions before passing through the pure water. It is considered desirable to exist in a state that is easily ionized by nitrite ions, bromine ions, sulfate ions, and the like.

  Therefore, before impinger bubbling, the atmospheric gas in the clean room to be measured and the process gas used in the manufacturing process first generate corona or creeping, short-circuit discharge from the tip of the needle-like discharge electrode. You can pass through the space. This discharge is any one of AC, DC, pulse AC, and pulse DC, and is applied from the tip of a needle-like discharge electrode made of a conductor such as silicon, tungsten, iron, stainless steel or titanium to which a high voltage of 1000 V to 10000 V is applied. appear. The needle-like discharge electrode may be made of other materials as long as it is intended to generate a discharge. When passing through the discharge space, the inorganic impurity component contained in the gas to be measured is ionized by electron application and desorption. For example, inorganic impurity components such as fluorine compounds, chlorine compounds, nitrogen oxides, sulfur oxides, hydrogen sulfide, sulfur hexafluoride, etc. are subjected to discharge treatment, respectively, and the aforementioned fluorine ions, chlorine ions, nitrate ions, nitrite ions, It becomes bromine ion and sulfate ion. Thereafter, the gas to be measured is bubbled in pure water in the impinger. There are no particular restrictions on the amount of suction, such as flow rate and time, for suction during bubbling. Also, there is no restriction on the connection of two or more impinger containers instead of one. As a result, since the inorganic impurity component contained in the gas to be measured is ionized so as to be easily dissolved in pure water, it is efficiently collected by pure water which is an absorbing solution in the impinger.

  FIG. 9 is a schematic cross-sectional view of an atmospheric gas collecting device containing an inorganic impurity component according to the first embodiment. A discharge process unit including a needle-like discharge electrode 13 and a power source 12 is connected between the open / close valve 8 having the suction port 15 for sucking the atmospheric gas 1 in the clean room and the suction port 16 of the impinger 3. An open / close valve 8, a suction pump 2, a flow meter 11, and the like are connected behind the discharge port 17 of the impinger 3 as necessary. In the collection, the atmospheric gas 1 is sucked through the impinger by the suction pump 2, and the atmospheric gas 1 is allowed to pass through the corona discharge space generated from the discharge electrode 13 supplied with voltage from the power source 12. Then, the atmospheric gas sucked into the pure water in the impinger 3 is bubbled to dissolve the ionized inorganic impurity component in the pure water. After the collection, the open / close valve 8 is closed and sealed. At this time, the materials of the pipes (pipes or tubes) connecting each part are hydrocarbon tubes, silicone tubes, quartz glass tubes, stainless steel tubes, etc., and fluorine, nitrogen, sulfur, bromine, phosphorus, lithium, It is desirable that inorganic impurity components such as sodium, potassium and magnesium are 10% or less. This is because, during discharge, the inorganic impurity components in the tube are ionized by the generated ions, electrons, etc., resulting in contamination. Moreover, there is no restriction | limiting in particular in the length of a tube. The gas collection device shown in FIG. 9 is brought into a clean room or a manufacturing site in which cleanliness management and control are performed, the atmospheric gas therein is sucked and bubbled to the collection device, and inorganic impurity components are removed. Collect. By analyzing the collected inorganic impurity components with a required analyzer, evaluating the cleanliness, and feeding back, the cleanliness in the clean room can be appropriately managed.

In Example 1, a voltage of ± 5500 V was applied to the tungsten discharge electrode, and a clean room atmosphere gas was sucked into 100 ml of pure water at a suction flow rate of 2 l / min for 2 hours, for a total of 240 l with one impinger vessel. The inorganic impurity components in the pure water collected by bubbling were evaluated by an ion chromatography analyzer. In the present invention, the analyzer itself is not particularly limited, and a different analysis method such as ion chromatography mass spectrometry may be used as necessary.
The bar graph of FIG. 10 shows the evaluation results for the inorganic impurity components collected at two measurement points in the clean room according to Example 1. As a comparative example, the evaluation results of the inorganic impurity components which are different from each other in that they are collected by conventional bubbling without passing through the discharge process at substantially the same measurement point are shown on the horizontal axis of FIG. FIG. 10 is a graph showing examples of fluoride ion, sulfide ion, NO ₂ ion, and NO ₃ ion, each having an inorganic impurity component concentration on the vertical axis and an arbitrary two measurement points in the clean room on the horizontal axis. 1 and a comparative example are shown. The dissolution of the ionic component in the atmospheric gas through the discharge process according to the present invention into pure water has a high dissolution effect of 3 to 64 times compared to the collection by bubbling without the discharge process of the comparative example. It can be seen that it is collected very efficiently. In addition, as shown in the comparative example, when the inorganic impurity component is not detected by the impinger in the conventional collection method or is below the detection level, the inorganic impurity component is ionized by the discharge process according to the present invention. It can be seen that system impurity components can be collected. Therefore, according to the present invention, it is clear that the inorganic impurity component can be efficiently collected by this discharge process.

FIG. 11 is a schematic cross-sectional view of a process gas collecting apparatus containing an inorganic impurity component according to the second embodiment. A gas inlet 15 and an open / close valve 8 are connected to a nitrogen gas pipeline or an air pipeline used in a semiconductor wafer process, and a discharge electrode 13, a power source 12, an impinger 3, a suction pump 2, similar to the first embodiment, Connect the flow meter 11. At this time, the connecting pipe (pipe or tube) is made of a low impurity material for the same purpose as in the first embodiment. This is connected to a nitrogen gas pipeline or air pipeline to be measured, and the nitrogen gas and air are bubbled and collected for evaluation and analysis.
In Example 2, a total of 1200 l of gas and air were sucked at a flow rate of 10 l / min for 2 hours. The inorganic impurity component and the metal component in pure water collected by bubbling nitrogen gas and air gas that passed through the discharge process were evaluated by an ion chromatography analyzer or an ion chromatography mass spectrometer. The evaluation results are shown in FIG.
In FIG. 12, as a comparative example, the evaluation results of the inorganic impurity components bubbled and collected without passing through the discharge process are shown. The dissolution of ionic components in the air through the discharge process according to the present invention into pure water has a dissolution effect that is 2 to 240 times that of collection by bubbling without the discharge process of the comparative example. It shows that it is collected very efficiently. It is clear that the inorganic impurity component can be efficiently collected by this discharge process.

  As Example 3, in the case of bubbling collection without discharge of the conventional method and bubbling collection having the discharge process of the present invention in Table 1 below, the amount of sulfate ions in the atmospheric gas in the semiconductor production line in the clean room is shown. The results of collection and analysis are shown. As the gas collection device, a discharge process unit, an impinger, a suction pump, and a flow meter, which are the same gas collection device as in Example 1, were used. Even in atmospheric gases in a semiconductor production line where sulfate ions are not detected by conventional collection, the collection efficiency is improved by providing a discharge process according to the present invention and bubbling, and detection of inorganic impurity components can be achieved. I understand that it is possible.

以上述べてきたように実施例１〜３によれば、半導体製造プロセスに悪影響を及ぼす恐れのある無機系不純物成分などについて、クリーンルーム内の、雰囲気気体中やプロセスガス、空気中などにおける無機系不純物成分量を簡便に知ることが可能となる。測定気体に含まれる無機系不純物成分量を知ることにより、クリーンルーム内の、雰囲気気体中やプロセスガス中の無機系不純物成分量の管理基準および制御レベルを明確にすることができ、製品の歩留まりおよび信頼性が向上する。

As described above, according to the first to third embodiments, inorganic impurities in a clean room, in an atmospheric gas, process gas, air, etc., with respect to inorganic impurities that may adversely affect the semiconductor manufacturing process. It becomes possible to know the amount of components easily. By knowing the amount of inorganic impurity components contained in the measurement gas, it is possible to clarify the management standards and control levels of the amount of inorganic impurity components in the atmosphere gas and process gas in the clean room. Reliability is improved.

FIG. 3 is a flow diagram of a method for collecting and analyzing inorganic impurity components in an atmospheric gas and a process gas according to the present invention. It is a schematic sectional drawing of the conventional collection apparatus of the inorganic impurity component by the impinger which uses atmospheric gas as measurement object gas. It is a schematic sectional drawing of the conventional collection apparatus by the impinger which uses process gas as measurement object gas. It is a schematic sectional drawing of the conventional collection apparatus using the semiconductor wafer which uses atmospheric gas as measurement object gas. It is a schematic sectional drawing of the conventional collection apparatus using the semiconductor wafer which uses process gas as measurement object gas. It is a schematic sectional drawing of the conventional collection apparatus using the direct or adsorbent which uses atmospheric gas as measurement object gas. It is a schematic sectional drawing of the conventional collection apparatus using the direct or adsorbent which uses process gas as measurement object gas. It is the conventional collection method of an inorganic impurity component in atmospheric gas and process gas, and a flow chart of an analysis method. It is a schematic sectional drawing of the collection apparatus which uses atmospheric gas as measurement object gas concerning this invention. It is a bar graph which shows the measurement result of the inorganic type impurity ion component in the atmospheric gas in a clean room concerning this invention. It is a schematic sectional drawing of the collection apparatus which uses process gas as measurement object gas concerning this invention. It is a bar graph which shows the measurement result of the inorganic type impurity ion component in nitrogen gas and air concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Atmospheric gas 2 Suction pump 3 Impinger 4 Collection solution 5 Process gas 6 Silicon wafer 7 Mounting stand 8 Opening and closing valve 9 Collection container 10 Adsorbent 11 Flow meter 12 Power supply 13 Discharge electrode 15, 16 Intake port 17 Exhaust port.

Claims (4)

A gas collecting device comprising a discharge electrode for generating discharge in the middle of a tube connecting between a measurement gas suction port and an impinger suction port. The discharge electrode has a needle-like tip capable of emitting corona, creepage and short-circuit discharge, and is connected to a power source capable of applying a voltage of 1000V to 10000V direct current, alternating current or pulsed direct current, pulsed alternating current. The gas collection device according to claim 1, wherein Inhale the measurement gas, bring it into contact with the discharge space where discharge occurs, bubbling the solution in the impinger, collect the measurement gas from the outlet, and detect the cleanliness of the gas with a gas analyzer A gas evaluation and analysis method characterized by the above. 4. The method for evaluating and analyzing a gas according to claim 3, wherein the measurement gas is an atmospheric gas or a gas used in a process for manufacturing a semiconductor or a recording medium.

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