JP2006275551A - Evaluation method of contamination state of substrate-manufacturing local space - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for evaluating accurately the contamination state of a local space passed by a substrate at the substrate manufacturing time. <P>SOLUTION: This evaluation method of the contamination state of the local space in a substrate manufacturing process has characteristics, wherein in the substrate manufacturing process, a passive sampler is put into the local space passed by the substrate, and contaminants in the space are collected into an adsorbent in the passive sampler, and then the adsorbed contaminant is eliminated from the adsorbent, and the eliminated contaminant is analyzed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for evaluating a contamination state in a local clean space through which a substrate passes during manufacture of the substrate.

  In the manufacture of equipment using electronic substrates (hereinafter referred to as substrates) such as semiconductor wafers, liquid crystal substrates, magnetic disks, etc., contaminants such as organic substances in the manufacturing space are adsorbed on the substrate, and so on. Since the yield and quality are lowered, the process for manufacturing such a device is performed in a clean room. Then, it is necessary to evaluate the state of contamination due to the organic matter etc. in the clean room in each manufacturing process. For example, the air in the clean room sucked by the suction pump is passed through the adsorbent at a constant flow rate. A method has been proposed in which contaminants in the air are collected in an adsorbent and the collected contaminants are analyzed (see, for example, Non-Patent Document 1).

  By the way, in recent years, with the progress of miniaturization of substrate circuits, it has been demanded that a clean room has a higher level of cleaning space, and with the increase in size of substrates, a large-scale clean room is required. It has become to. In recent years, the use of a local clean method has been proposed as a cost saving means for securing such a clean space. For example, a portable and airtight substrate transport container such as a FOUP (Front Opening Unified Pod) or SMIF (Standard Mechanical Interface) pod is interposed between various processing processes in each clean room in a series of manufacturing of the above equipment. The substrate and the EFEM (Equipment Front End Module) attached to the container hold a local clean space, and the substrate processed in each process is stored in the substrate transport container and transported to the next process. Proposed.

  And about said board | substrate conveyance container and mounting components intervened in each process, it is necessary to evaluate the contamination state of the local space formed by this, For example, as a technique, a board | substrate conveyance container is used. After storing a stored item such as a semiconductor wafer in a storage or transfer for a predetermined time, take out the stored item from the substrate transfer container, and then desorb the contaminants attached to the surface of the stored item, A method for measuring the desorbed contaminant has been proposed (see, for example, Patent Document 1).

“Appendix 3 Method for Measuring Organic 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. 9-12 Japanese Patent Laid-Open No. 2004-340685

However, FOUP, SMIF pod, and EFEM have a much smaller space volume than a clean room and are sealed systems, and it is difficult to suck and collect using a pump. In this case, the amount of pollutants collected by the adsorbent may be smaller than the amount of pollutants contained in the atmosphere through the adsorbent. In the quantitative analysis of pollutants in the target space, the analytical value may fall below the lower limit of quantification, and the accuracy of the assessment of the contamination state was not fully satisfactory.
Under such circumstances, the problem to be solved by the present invention is to provide a method for accurately evaluating the contamination state of a local space through which the substrate passes during the manufacture of the substrate.

  That is, according to the present invention, in the substrate manufacturing process, a passive sampler is placed in a local space through which the substrate passes, and contaminants in the space are collected in an adsorbent in the passive sampler. The present invention relates to a method for evaluating the contamination state of the local space, characterized in that the adsorbed contaminant is desorbed from the sample and the desorbed contaminant is analyzed.

  According to the method of the present invention, the contamination state of the local space in the substrate manufacturing process can be accurately evaluated, and this method is useful for securing a clean space in the substrate manufacturing facility.

  The local space in the substrate manufacturing process according to the present invention is a local space through which these substrates pass when manufacturing substrates such as semiconductor wafers, liquid crystal substrates, and magnetic disks, and is SEMI (Semiconductor Equipment and Materials International). Standard FOUP (Front Opening Unified Pod), SMIF (Standard Mechanical Interface) pod, EFEM (Equipment Front End Module), substrates described in JP 2000-58633 A, JP 2001-85507 A, etc. Examples include a transport container and its mounting parts.

  As the passive sampler of the present invention, an apparatus in which a container made of a gas permeable membrane is filled with an adsorbent is usually used. The gas permeable membrane is preferably made of a material that does not affect the analysis of the pollutant to be analyzed. Usually, particles such as polyolefin resin such as polyethylene, polyester resin, and fluororesin are sintered or What was welded is used. Preferably, it is a fluororesin film. As the adsorbent, a porous polymer adsorbent, a graphite carbon adsorbent, activated carbon, or the like is used.

  Examples of the passive sampler include devices described in JP-A No. 2002-5797, JP-A No. 2002-357517, JP-A No. 2004-191120, and the like. Moreover, you may use a commercial item (For example, the sperco Japan company make, brand name "VOC-TD" etc.).

  In the use of a passive sampler, it is preferable that a container made of a gas permeable membrane is sufficiently washed beforehand with an organic solvent such as acetone or hexane, pure water, etc. and dried. In addition, it is preferable to perform in advance a heat treatment of the adsorbent, for example, a process of heating the adsorbent to 300 ° C. or higher while passing an inert gas. Here, the inert gas means a gas that does not affect the analysis of the pollutant to be analyzed, and depending on the type of pollutant to be analyzed, such gas includes nitrogen, An inert gas such as argon or helium; air or the like is used.

  The residence time of the passive sampler in the local space, that is, the time required to collect the contaminants in the space is usually 2 to 24 hours, preferably 10 to 24 hours.

  In the analysis of pollutants collected by the passive sampler, the adsorbent is taken out from the passive sampler, and the pollutant is desorbed from the adsorbent by the thermal desorption method or solvent extraction method. Analyze by.

  The heat desorption method is performed, for example, by transferring the adsorbent to a commercially available heat desorption tube, heating the heat desorption tube, and venting an inert gas. The temperature and time for performing the heat desorption vary depending on the contaminant to be analyzed, but the heat desorption temperature is usually 250 to 350 ° C., preferably 250 to 300 ° C. The heat desorption time is usually 10 minutes or more, preferably about 20 minutes. On the other hand, in the solvent extraction method, for example, an adsorbent taken out from a passive sampler is put in a solvent, and contaminants are extracted and eluted from the adsorbent. The solvent is appropriately selected depending on the contaminant to be analyzed.

  As a method for analyzing the contaminants desorbed from the adsorbent, a known method is used. Examples of the thermal desorption method include a gas chromatograph (GC) method and a gas chromatograph-mass spectrometry (GC-MS) method. Examples of the solvent extraction method include a gas chromatograph (GC) method, a liquid chromatograph (LC) method, a gas chromatograph-mass spectrometry (GC-MS) method, and a capillary electrophoresis (CE) method. The GC-MS method is preferred. In the above analysis, the pollutant desorbed from the adsorbent is introduced into a tube cooled with a refrigerant such as liquid nitrogen as necessary to condense the pollutant. You may analyze after performing the concentration process of concentrating the liquid containing.

  According to the method of the present invention, the contamination state of the local space in the substrate manufacturing process can be accurately evaluated, and this method is useful for securing a clean space in the substrate manufacturing facility. In particular, the present invention is a local form formed by a substrate transport container such as a FOUP (Front Opening Unified Pod), SMIF (Standard Mechanical Interface) pod, EFEM (Equipment Front End Module) or the like and a mounting part thereof with a small amount of contaminants. Useful for assessing the pollution status of a space.

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

Example 1
A passive sampler (manufactured by Spelco Japan, trade name “VOC-TD”, adsorbent: graphite carbon-based adsorbent) was left in a clean room for 24 hours, and organic substances in the air in the clean room were collected by a passive sampler. Next, the adsorbent is transferred from the passive sampler to a glass tube with a diameter of 6 mm x 16 cm, set in a heat desorption concentrator (GL Science, CP4020 type), and heated and desorbed at 300 ° C for 10 minutes. The gas was concentrated with liquid nitrogen and analyzed with a gas chromatograph-mass spectrometer (HP-5993N type, manufactured by Agilent Technologies). The analysis results are shown in Table 1. In addition, about the detected organic substance, the total amount was represented as the amount of toluene conversion.

(Comparative Example 1)
Using a suction pump, air in the clean room was passed through a collection tube (diameter 6 mm x length 16 cm) filled with 90 mg of graphite carbon-based adsorbent at a flow rate of 0.1 L / min for 24 hours. Of organic material was collected in a collection tube. Next, the adsorbent is transferred from the collection tube to a glass tube having a diameter of 6 mm × 16 cm, set in a heat desorption concentrator (GL Science, CP4020 type), and heat desorbed at 300 ° C. for 10 minutes. The generated gas was concentrated with liquid nitrogen and analyzed with a gas chromatograph-mass spectrometer (HP-5993N type, manufactured by Agilent Technologies). The analysis results are shown in Table 1. In addition, about the detected organic substance, the total amount was represented as the amount of toluene conversion.

Claims (1)

In the substrate manufacturing process, a passive sampler is placed in a local space through which the substrate passes, and the contaminant in the space is collected in the adsorbent in the passive sampler, and then the contaminant adsorbed from the adsorbent. A method for evaluating a contamination state of a local space in a substrate manufacturing process, wherein the desorbed material is desorbed and the desorbed contaminant is analyzed.