JP2003344239A - Measuring instrument for molecular contaminant generated from clean room constitutive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To conduct measurement under a condition approximated to an actual clean room environment, and to provide excellent measuring precision. <P>SOLUTION: This measuring instrument is provided with a measuring container 2 set with a clean room constitutive material, a flow means 3 for allowing carrier gas G to flow in the measuring container 2, and an analyzing means 20 for analyzing an amount of a molecular contaminant in the carrier gas G flowing through the measuring container 2. In addition, a humidity control means 10 is provided to humidity-conditioning the carrier gas G flowing in the measuring container 2 by bubbling one portion of the carrier gas G flowing in the measuring container 2 in pure water W to be mixed thereafter with the rest of the carrier gas G. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring molecular pollutants generated from clean room constituent materials.

[0002]

2. Description of the Related Art A method for measuring molecular pollutants generated from constituent materials (for example, sealing materials, paints, plastic materials, filters, etc.) of clean rooms (for example, for manufacturing semiconductors, liquid crystals, photomasks, etc.) , Japan Air Purification Association has issued a guideline (“Guideline for measuring molecular pollutants generated from clean room constituent materials” issued on July 31, 1999). The measurement is performed according to the guidelines. By performing this measurement, it is possible to select a material for the purpose of reducing the molecular pollutants generated from the interior materials of the clean room or the installation machine, and also to calculate the approximate value of the molecular pollutant concentration in the clean room. It is possible to guess.

When the accuracy of material selection and concentration estimation is to be ensured, of course, in an actual clean room environment (usually temperature 23 ° C., humidity 45% RH, wind speed 0.3 m / s,
It is preferable to perform the measurement under the condition that the ventilation rate is close to 360 times / h), and the above-mentioned guideline corresponds to the dynamic headspace engineering test method (hereinafter, simply referred to as DHS-E method).

In the dynamic headspace method, a test body (material for forming a clean room) is placed in a measuring container, a carrier gas is continuously circulated, and molecular contaminants contained in the outflow carrier gas are adsorbed or absorbed. This is a method of collecting and analyzing with a liquid or the like. The engineering method is a method in which measurement by the dynamic headspace method is performed under normal temperature and constant humidity conditions in consideration of a clean room environment.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The law had the following problems. That is, D
In the HS-E method, since the measurement is performed under the condition of constant humidity, it is necessary to adjust the humidity of the carrier gas before flowing in the measurement container. However, a measuring device that preferably performs this humidity control, specifically, "a condition that a molecular pollutant is generated from the humidity control means itself and the molecular pollutant is mixed into the carrier gas. Since the measurement accuracy is excellent, and because the humidity of the carrier gas can be freely set, it is possible to perform measurements in a state similar to the actual clean room environment. ” Not really.

[0006] Also, the clean room constituent materials generate a small amount of pollutants, and in particular, the constituent material called an outgas countermeasure product has a value several orders of magnitude smaller than that of general building materials. When the flow rate of the carrier gas is adjusted so that the same wind speed (0.3 m / s) is obtained and the measurement is performed, the concentration of the molecular pollutants is lowered, and for example, the gas chromatograph mass spectrometry method which is generally adopted ( The value is below the lower limit of quantification (about 0.1 μg / m ³ ) of JIS K 0123).
Therefore, in practice, very slow wind speeds (eg 3 ×
10 ^{−5 to} 7 × 10 ⁻⁴ m / s. ) Is used for relative comparison. However, the rate of mass transfer in the molecular pollutant generation process may be either the evaporation process on the surface of the constituent material or the diffusion process inside the constituent material. Since the wind speed of 1 has a great influence on the generation of molecular pollutants, accurate measurement results cannot be obtained by relative comparison.

Therefore, a main object of the present invention is to provide an apparatus for measuring molecular pollutants generated from a clean room constituent material, which can perform measurement in a state close to an actual clean room environment and which is excellent in measurement accuracy. Especially.

[0008]

The present invention, which has solved the above-mentioned problems, is as follows. <Invention of Claim 1> A measuring container in which a clean room constituent material is installed, a flow means for circulating a carrier gas in the measuring container, and an amount of a molecular contaminant in the carrier gas passing through the measuring container. A device for measuring molecular contaminants, which comprises: analyzing means for analyzing the carrier gas, bubbling a part of the carrier gas to be circulated in the measuring container in pure water, and then mixing with the rest of the carrier gas. According to the above, there is provided a humidity control means for controlling the humidity of the carrier gas circulated in the measurement container, and the apparatus for measuring a molecular contaminant generated from a clean room constituent material.

<Invention of Claim 2> A measuring container in which a clean room constituent material is installed, and a wind velocity on the surface of the constituent material in the measuring container is 3 × 10 ^{−5 to} 7 × 10 ⁻⁴ m.
A flow means for circulating a carrier gas at a flow rate expected to be / s, and an analyzing means for analyzing the amount of molecular contaminants in the carrier gas that has passed through the measurement container.
A device for measuring molecular contaminants having, comprising a stirring means for stirring the carrier gas in the measurement container, by stirring the carrier gas in the measurement container by this stirring means, in the surface of the constituent material An apparatus for measuring molecular pollutants generated from a clean room constituent material, characterized in that the wind speed of a carrier gas is increased from a predetermined value to a predetermined value.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 shows a measuring device 1 according to this embodiment.
The measurement apparatus 1 includes a humidity control means 10 for controlling the humidity of the carrier gas G, a measurement container 2 for installing a clean room constituent material, and a flow means for circulating the carrier gas G in the measurement container 2. 3 and an analysis means 20 for analyzing the amount of molecular contaminants in the carrier gas G that has passed through the measurement container 2.

In this measuring apparatus 1, the carrier gas G
Use clean air as. This clean air is, for example,
Acid, alkali, organic chemical filter or U not shown
After removing chemical components such as acidic components, alkaline components and organic components contained in the outside air A and dust components through an LPA filter or the like, it can be obtained through the adsorption tower 4 filled with activated carbon.

Before the carrier gas G is circulated in the measurement container 2, first, the humidity of the carrier gas G is adjusted by the humidity adjusting means 10 so as to be the same as the actual clean room environment, for example, the humidity is adjusted to 45% RH. To do. This humidity control means 10
Is mainly composed of a storage tank 11 in which pure water W is stored, flow rate control valves 12 and 13, and a mixing tank 14.

A part of the carrier gas G passed through the adsorption tower 4 is blown into the pure water W in the storage tank 11 through the flow pipe 15. The carrier gas G humidified by being blown into the pure water W is sent from the inside of the storage tank 11 to the inside of the mixing tank 14 through the flow pipe 16 provided with the flow rate control valve 12. On the other hand, in the mixing tank 14, the carrier gas G passed through the adsorption tower 4
The remaining part of the above is sent through the flow pipe 17 equipped with the flow control valve 13 in the middle without being humidified. Therefore, in the mixing tank 14, the moistened carrier gas G and the non-humidified carrier gas G are mixed. This mixing ratio can be performed by adjusting the flow rate control valves 12 and 13. If the mixing ratio is adjusted, the humidity of the carrier gas G is adjusted accordingly. That is, it is difficult to accurately adjust the humidity by simply bubbling the carrier gas G, but the humidity control means 10 of the present embodiment can accurately adjust the humidity. Moreover, since the method of humidification is bubbling, there is no risk of molecular contaminants being mixed in the carrier gas G.

The carrier gas G, the humidity of which has been adjusted in this way, is sent to the measurement container 2 through the flow pipe 18 and circulated therein. The measuring container 2 is warmed by being installed in a constant temperature bath 5 whose internal temperature is set to 23 ° C., for example. Further, in the measurement container 2, as schematically shown in FIG. 2, the stirring means for stirring the carrier gas G in the measurement container 2, in the present embodiment, only the stirring blade 31 is provided in the measurement container 2 (bottom portion). A magnetic stirrer 30 configured to be located is provided. By stirring the carrier gas G in the measuring container 2 with the magnetic stirrer 30, the wind speed of the carrier gas G on the surfaces of the clean room constituent materials S and S is changed from a predetermined value (the meaning of the predetermined value will be described later) to a predetermined value. It has a speedy configuration. The predetermined value (accelerated wind speed) is preferably a value that is close to the wind speed in an actual clean room environment. For example, in a normal case (0.3 m / s), the average may be 0.1 to 0.5 m / s, preferably 0.2 to 0.4 m / s. By setting the specified value (accelerated wind speed) to a value that is close to the wind speed in an actual clean room environment, the rate of molecular pollutant generation is also close to the actual value, and therefore accurate measurement results can be obtained. become able to. The wind speed can be adjusted by changing the size of the stirring blade, the rotation speed, or the like.

Reference numeral 2C in the drawing is a base for installing the clean room constituent materials S, S, and is a cylindrical body 2C having upper and lower surfaces opened.
A net plate 2CB for installing the clean room constituent materials S, S in A is installed substantially horizontally. In addition, it passes through the lower end edge of the cylindrical body 2CA,
The long dotted line indicates upward along the peripheral surface and further entering from the upper surface of the cylinder 2CA into the cylinder 2CA.
This shows a state in which the carrier gas G circulates in the measurement container 2, and by this circulation, the wind speed on the surfaces of the clean room constituent materials S, S is increased from a predetermined value to a predetermined value.

By the way, if the flow rate of the carrier gas G is increased in order to increase the wind speed on the surface of the clean room constituent material, the concentration of the molecular pollutant is lowered, as described above, and the analysis cannot be performed. However,
In the present invention, while keeping the flow rate of the carrier gas G at the “same as in the case of the conventional method”, that is, “the wind velocity on the constituent materials S and S surface is 3 × 10 ^{−5 to} 7 × 10 ^−4.
The air velocity on the surface of the actual constituent material is increased to a predetermined value by the stirring by the stirring means while keeping the amount "m / s is expected". Is increased and therefore the analysis can be performed reliably.

In this specification, in order to specify the flow rate of the carrier gas, the wind speed (3 × 10 ^{-5 to} 7 × 10 ^-4 m / s) generated on the surface of the material constituting the clean room is used.
The actual wind speed was increased by stirring by the stirring means, and the wind speed (3 × 10 ^{−5 to} 7 × 10 ⁻⁴ m /
Since s) is only a planned value, it is called a planned value. Further, in order to increase only the wind speed while suppressing the flow rate of the carrier gas, it is conceivable to reduce the cross-sectional area of the pipe or the like for allowing the carrier gas to flow into the measurement container. A large difference in wind speed occurs depending on the part, and it becomes impossible to generate a substantially uniform wind speed over the whole area, so that an accurate analysis cannot be performed.

In the present embodiment, the flow and flow rate of the carrier gas G are adjusted by the flow means 3 such as a suction pump provided downstream of the measuring container 2 and the flow control valve 12 described above.
And 13 and. The distribution means 3 may be, for example, a pressure pump provided upstream of the measurement container 2. However, from the viewpoint of preventing molecular contaminants generated from the distribution means itself from being mixed into the carrier gas, it is preferable to provide the measurement container 2 downstream.

By the way, the carrier gas G is drawn by the suction method.
When the measurement container 2 is configured to circulate in the measurement container 2, if the measurement container 2 is not completely sealed, molecular contaminants or the like may enter the measurement container 2 and an accurate measurement result may not be obtained. Therefore, in the present embodiment, as shown schematically in FIG.
Flange portions F and F are provided on the lid 2A and the main body 2B which are used when the lid 2A and the main body 2B are installed, and the sealing portion is made more complete by widening the contact portion between the lid 2A and the main body 2B. Further, the contact portion between the lid 2A and the main body 2B was constituted by a packing P made of Teflon (registered trademark) to make the adhesion more complete and prevent generation of molecular contaminants.

As described above, the carrier gas G exposed to the clean room constituent materials S, S flows out from the measurement container 2 and is sent to the analysis means 20 through the flow pipe 19. The analyzing means 20 includes a collecting means 21 for collecting the molecular contaminants in the carrier gas G, a gas chromatograph mass spectrometer for analyzing the amount of the molecular contaminants collected by the collecting means 21, and the like. Not mainly from analyzers.

The form of the collecting means 21 is not particularly limited, and it may be a solution absorbing means, a solid absorbing means, or the like. In the present embodiment, as the collection means 21, a collection pipe provided coaxially with the distribution pipe 19 in the middle of the distribution pipe 19 and a molecular contaminant filled in the collection pipe are provided. A solid adsorbent that adsorbs,
I used the main one from. Examples of the solid adsorbent include porous polymer adsorbents (TENAX-GR and the like),
Activated carbon or the like can be used. The molecular contaminants adsorbed by the solid adsorbent are analyzed by an analyzer (not shown) to quantify the molecular contaminants.

[0022]

[Example] In order to confirm that the difference in the wind speed on the surface of the clean room constituent material affects the measurement result, an experiment was conducted with the measuring apparatus of the present embodiment described above. <Example 1> As a clean room constituent material (test body), a silicone sealant (1 component) used for sealing joints of members in a clean room for semiconductor and liquid crystal production, and for sealing around ducts, pipe joints, through pipes, etc. Oxime type) was used. Silicone sealing material is 20mm on Teflon (registered trademark) sheet
It was applied and used to have a size of × 20 mm × 2 mm.

Prior to the measurement, each part such as the measuring container 2 and the flow pipe 15 was washed with an organic solvent and pure water and baked at 260 ° C. for 12 hours. Carrier gas G has a humidity of 40%
It was adjusted to RH and circulated in the measurement container 2 at a flow rate of 2 L / min (air velocity on the surface of the test body of 5 × 10 ⁻⁴ m / s). As the measuring container 2, a SUS having a double cylindrical structure
A product having a capacity of 20 L was used.

When the stirring blades 31 are rotated, vertical circulation air is generated in the measuring container 2, and the clean room constituent materials S,
The wind speed on the S surface was 0.3 m / s. This wind speed was confirmed by a hot wire anemometer. The analysis of the molecular contaminants collected by the collecting means 21 was performed by a gas chromatograph mass spectrometer.

FIG. 3 shows the concentration change of the oxime, FIG. 4 shows the concentration change of the low molecular weight cyclic siloxane tetramer (D4), and FIG.
Shows the concentration change of the low molecular weight cyclic siloxane pentamer (D5). For each, the case where the stirring blade 31 is rotated to generate the circulating air and the case where the stirring blade 31 is stopped and the circulating air is not generated are shown.

There was no significant difference in oxime depending on the presence or absence of circulating air, but there was a large difference in D4 and D5 which are important control substances in the semiconductor clean room. Therefore, it can be seen that accurate measurement results cannot be obtained if the wind velocity on the surface of the clean room constituent material is different from that in the actual environment.

Example 2 As a clean room constituent material (test body), an oil resistant butyl rubber gasket used as a gasket for a duct flange in a clean room for semiconductor and liquid crystal production was used. The oil-resistant butyl rubber gasket was formed into a size of 148 mm × 148 mm × 3 mm, adhered on a Teflon (registered trademark) sheet, and measured. Other implementation conditions were the same as in Example 1.

FIG. 6 shows changes in the concentration of total organic components (TVOC). It can be seen that the presence or absence of circulating air causes a difference of more than twice, and accurate measurement results cannot be obtained unless the wind speed on the surface of the clean room constituent material is approximated.

[0029]

As described above, according to the present invention, it is possible to perform a measurement in a state close to an actual clean room environment, and a measuring device for a molecular contaminant generated from a clean room constituent material excellent in measurement accuracy. Becomes

[Brief description of drawings]

FIG. 1 is a configuration diagram of a measuring device according to an embodiment.

FIG. 2 is a schematic diagram of a measurement container.

FIG. 3 is a diagram showing changes in the oxime concentration of the sealing material.

FIG. 4 is a diagram showing a change in D4 concentration of a sealing material.

FIG. 5 is a diagram showing a change in D5 concentration of a sealing material.

FIG. 6 is a diagram showing a change in TVOC concentration of butyl rubber.

[Explanation of symbols]

1 ... Measuring device, 2 ... Measuring container, 3 ... Distribution means, 10 ... Humidity controlling means, 21 ... Collection means, A ... Outside air, G ... Carrier gas, W ... Pure water.

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 502195835             Limited company ad tech             185-1 Shinyoshida-cho, Kohoku-ku, Yokohama-shi, Kanagawa             N-port 1st floor (72) Inventor Masazumi Kobe             7033-182 New in Sumisuji, Miyagawa, Chino City, Nagano Prefecture             Within Japan Air Conditioning Co., Ltd. (72) Inventor Shinichi Tanabe             4-5-6-4 Yurinokidai, Yachiyo City, Chiba Prefecture             -1303 (72) Inventor Takao Ariga             185-1 Shinyoshida-cho, Kohoku-ku, Yokohama-shi, Kanagawa             N-Port 1st floor Inside Adtech Co., Ltd. F term (reference) 2G052 AA03 AA04 AA05 AB22 AC13                       AD02 AD22 AD42 BA05 CA04                       CA11 FB02 FC02 FC13 GA24                       GA27 HC23 HC29 JA09

Claims (2)

[Claims] 1. A measuring container in which a clean room constituent material is installed, a flow means for circulating a carrier gas in the measuring container, and an amount of a molecular contaminant in the carrier gas passing through the measuring container is analyzed. Analyzing means, a measuring device for molecular contaminants having, after bubbling a part of the carrier gas to be circulated in the measurement container in pure water, by mixing with the rest of the carrier gas, An apparatus for measuring molecular pollutants generated from a clean room constituent material, comprising a humidity control means for controlling the humidity of a carrier gas to be circulated in a measurement container. 2. A measuring container in which a clean room constituent material is installed, and a flow rate in which the wind velocity on the surface of the constituent material in the measuring container is expected to be 3 × 10 ^{−5 to} 7 × 10 ⁻⁴ m / s. A measuring device for molecular contaminants, comprising: a means for circulating the carrier gas, and an analyzer for analyzing the amount of the molecular contaminants in the carrier gas that has passed through the measuring container. A stirring means for stirring the carrier gas inside, and by stirring the carrier gas inside the measurement container by this stirring means, the wind speed of the carrier gas on the surface of the constituent material is configured to be increased from a planned value to a predetermined value. An apparatus for measuring molecular pollutants generated from clean room constituent materials.