JPH10165744A - Gaseous organic impurity treatment system - Google Patents

Abstract

(57) [Problem] To provide a system capable of effectively removing gaseous organic impurities with a small pressure loss. SOLUTION: In a gaseous organic impurity treatment system 1 which removes gaseous organic impurities contained in the gas to generate clean air by permeating the gas, a high porosity which allows the gas to pass through is provided. A chemical filter 2 having a structure in which granular activated carbon is supported on the surface of the voids of the porous body, and a chemical filter 2 disposed downstream of the chemical filter 2;
An activated carbon layer 3 that does not generate gaseous organic impurities and a filter 4 that is disposed downstream of the activated carbon layer 3 and that removes particulate impurities are provided. In addition, the chemical filter 2 supports a carbonaceous synthetic adsorbent composed of a thermal decomposition product of a granular macroporous synthetic polymer to extend the life of the system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gaseous organic impurity treatment system for purifying a gas, which is suitably used, for example, in a clean room for manufacturing a semiconductor device (LSI) or a liquid crystal display (LCD). About.

[0002]

2. Description of the Related Art Today, clean rooms are widely used for manufacturing semiconductors and LCD panels. For example, a semiconductor production line from a bare wafer to the production of 1MDRAM chips includes about 200 processes.
An LCD panel production line from the production of a glass substrate to the production of a 9.4-type TFT includes about 80 steps. In these production lines, it is difficult to always continuously flow a wafer or a glass substrate through each process. For example, in a TFT-LCD manufacturing line, it takes about several hours to several tens of hours for a semi-finished substrate on which a circuit has been completely formed in a previous process to be transferred to the next process. In the (stocker), it stands by while exposing to the clean room atmosphere.

When semiconductor substrates and LCD substrates are left in a clean room atmosphere for a long time, organic substances derived from the clean room atmosphere adhere to the surfaces of the substrates.
When an organic substance adheres to a silicon wafer as a semiconductor substrate, the following inconvenience occurs. In other words, the insulating oxide film (SiO
_{When 2} ) is formed, the carbon component in the organic substance is taken into the insulating oxide film (SiO ₂ ), causing a problem that the withstand voltage of the insulating oxide film is greatly reduced and the leak current is greatly increased. In addition, due to the adsorption of organic substances on the silicon wafer surface, the adhesiveness of the resist film deteriorates,
Exposure or etching failure may occur, making accurate pattern formation impossible. In addition, the surface resistivity of the wafer is increased, and the wafer is likely to be charged, and the fine particles floating in the air are easily electrostatically attracted to the wafer surface, so that the dielectric breakdown is more likely to occur. In addition, organic impurities contained in the clean room atmosphere cause a decrease in optical efficiency due to fogging of optical lenses and mirrors of an exposure apparatus and the like. In addition, there is also a problem that the organic impurities contained in the clean room atmosphere cause a photochemical reaction due to the ultraviolet rays of the optical equipment, and the products adhere to the wafer surface by the photo-CVD reaction surface. In the case where amorphous silicon (a-Si) for a thin film transistor (TFT) is formed on the surface of a glass substrate which is an LCD substrate while organic substances derived from the atmosphere adhere to the glass substrate, the glass substrate and a
-Poor adhesion of the Si film occurs. As described above, organic substances derived from the clean room atmosphere are used in semiconductor devices and LCDs.
Adversely affects the production of

On the other hand, organic substances adhering to the surface of the substrate can be removed by a cleaning technique such as ultraviolet / ozone cleaning. However, the cleaning time per substrate requires several minutes, and frequent cleaning causes a decrease in productivity. As described above, particularly in recent years, in addition to the contamination of the substrate by metal impurities and particles, the influence of the organic impurities existing in the clean room atmosphere on the semiconductor production has been regarded as a problem. For example, SEMATE in the United States
Technology announced by CH on May 31, 1995
ogy Transfer # 95052812A-T
R "Forecast of Airborne Mo
rectangular Containment Lim
it's for the 0.25 Micron H
highPerformance Logic Proc
As shown in Table 1, "ess" describes an organic contamination control level (permissible value of surface contamination) on the wafer surface. According to this description, in 1998, 5 × 1
A control level of 0 ¹³ carbon atoms / cm ^{2 and} a control level of 1 × 10 ¹⁵ carbon atoms / cm ^{2 in} a later step are required.

[0005]

[Table 1]

Therefore, conventionally, as a device for removing gaseous organic impurities contained in a clean room atmosphere, a chemical filter for adsorbing and removing gaseous organic impurities using activated carbon has been used. And, as the simplest form of a chemical filter using activated carbon,
BACKGROUND ART A packed tower having a structure in which granular activated carbon is packed in a predetermined case or the like is known. In addition, as other types, chemical filters composed of fibrous activated carbon combined with a binder of low-melting polyester or polyester non-woven fabric into a felt shape, or sheets in which granular activated carbon is firmly adhered to urethane foam or non-woven fabric with an adhesive Shaped chemical filters are also known.

[0007]

However, the packed column type chemical filter has a drawback that the efficiency of adsorbing organic substances is high, but the pressure loss (ventilation resistance) is high. In addition, felt-type and sheet-shaped chemical filters have excellent air permeability and adsorption efficiency is not so inferior to packed towers. However, filter media (eg, nonwoven fabric, binder, etc.) and adhesives that have activated carbon adhered to the sheet (For example, neoprene-based resin, urethane-based resin, epoxy-based resin, silicon-based resin, etc.) and a sealant (for example, neoprene rubber, silicone rubber, or the like) used to fix a filter medium to a surrounding frame.
The gaseous organic impurities generated from such factors may be included in the air after passing through the chemical filter, which may adversely affect the manufacture of semiconductors. In these felt-shaped and sheet-shaped chemical filters, gaseous organic impurities generated from the filter itself are again taken out and mixed into the air while removing trace organic impurities of the order of ppb contained in the clean room atmosphere once. Would.

The present invention has been made in view of the above-mentioned problems of the conventional gaseous organic impurity processing system, and provides a system capable of effectively removing gaseous organic impurities with a small pressure loss. It is in. Further, according to the present invention, it is possible to greatly extend the life of the chemical filter as compared with the related art.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention according to claim 1 is characterized by allowing gas to permeate.
In a gaseous organic impurity treatment system for removing gaseous organic impurities contained in the gas to generate clean air,
A chemical filter having a structure in which granular activated carbon is supported on the surface of a porous body having a high porosity and capable of transmitting gas, and an activated carbon which is disposed downstream of the chemical filter and does not generate gaseous organic impurities. And a filter disposed downstream of the activated carbon layer for removing particulate impurities.

According to a second aspect of the present invention, a gas is permeated in a gaseous organic impurity treatment system that removes gaseous organic impurities contained in the gas to generate clean air by permeating the gas. A chemical filter having a structure in which a carbonaceous synthetic adsorbent composed of a thermal decomposition product of a granular macroporous synthetic polymer is supported on the surface of a void portion of a porous body having a high porosity, and a downstream side of the chemical filter. And a filter arranged to remove particulate impurities.

In the second aspect of the present invention, an activated carbon layer which does not generate gaseous organic impurities may be provided between the chemical filter and the particulate impurity removing filter.

In the invention of the present application, the activated carbon used in the activated carbon layer may be any one of granular activated carbon, fibrous activated carbon and honeycomb activated carbon, or any combination thereof. It may be a combination. Further, as described in claim 5, the porous body constituting the chemical filter can be constituted by, for example, a plastic foam. In this case, the plastic foam is, for example, urethane foam. As described in claim 7, it is preferable that the filter for removing the particulate impurities is made of only a material that does not generate gaseous organic impurities.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a system for removing gaseous organic impurities according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory view schematically showing a configuration of a gaseous organic impurity removing system 1 according to an embodiment of the present invention. In this system 1, a chemical filter 2 is arranged at the most upstream side, an activated carbon layer 3 is arranged at a downstream side thereof, and a filter 4 is further arranged at a downstream side thereof in accordance with the flow order of air flowing through the clean room (clean room air).
Is arranged. The chemical filter 2, the activated carbon layer 3, and the filter 4 are integrally supported by a frame 5.

FIG. 2 is an enlarged view showing the structure of the chemical filter 2. As shown in the figure, the chemical filter 2 has a structure in which a spherical activated carbon 11 is supported on a porous body 10. A large number of voids 12 are formed in the porous body 10, whereby the porous body 10 has a high porosity that allows gas to permeate. As the porous body 10, for example, a plastic foam such as urethane foam can be used. The activated carbon 11 is carried by the adhesive 13 on the surface of the void 12 formed in the porous body 10.

FIG. 3 is a perspective view of the activated carbon layer 3, and FIG.
FIG. 4 is a sectional view taken along the line AA in FIG. 3. Activated carbon layer 3
Is designed not to generate gaseous organic impurities by itself, and the inside of the case 20 is filled with any one of granular activated carbon, fibrous activated carbon and honeycomb activated carbon, or any combination of these activated carbons 21. Configuration. Granular activated carbon can be obtained by thoroughly kneading coal or charcoal powder with a general agent such as pitch, molding, and firing at a high temperature. In addition, fibrous activated carbon is
It can be obtained by insolubilizing and activating carbon precursor fibers such as rayon, polyacrylonitrile (PAN), and pitch in a high-temperature atmosphere as starting materials. The honeycomb activated carbon can be obtained by molding a phenol resin into a honeycomb shape and baking it at about 800 ° C.

The case 20 is also preferably made of a material that does not generate gaseous impurities, such as stainless steel or aluminum, or an inorganic material from which gaseous impurities have been eliminated. Further, the clean room air passage surfaces (inflow side and outflow side) 22 of the case 20 are also formed of a gas permeable mesh or a perforated plate made of a material without degassing (for example, an inorganic material such as stainless steel or aluminum). Although not specifically shown, a thin mat made of fibrous activated carbon is sandwiched between a gas-permeable mesh or a perforated plate made of a material that does not degas (for example, an inorganic material such as stainless steel or aluminum). By itself, an “activated carbon layer that does not generate gaseous organic impurities” can be formed.

The filter 4 removes particulate impurities, and is composed of, for example, a medium-performance filter, a HEPA filter, or an ULPA filter. Thus filter 4
The reason for arranging on the downstream side is that activated carbon is used as the adsorptive filter medium of the chemical filter 2, so that particulate contaminants generated by crushing of the activated carbon itself are captured on the downstream side. This filter 4 is also preferably made of only a material that does not generate gaseous organic impurities. That is, a normal medium performance filter, HEPA filter or U
In the LPA filter, since a binder containing a volatile organic substance is used as a filter medium, degassing from the binder occurs. Therefore, use a filter medium that does not use such a binder, or use a filter medium from which volatile organic substances have been removed by baking even if a binder is used, and use a filter medium that is a means for fixing the filter medium to the frame. It is also desirable to select a type that does not generate degassing, or to fix the filter medium to the frame by physically pressing it with a material that does not degas.

FIG. 5 is an explanatory view schematically showing a configuration of a gaseous organic impurity removing system 1 'according to another embodiment of the present invention. Similar to the system 1 described above with reference to FIG. 1, this system 1 'also includes a chemical filter 2', an activated carbon layer 3 ', and a filter 4' arranged in the order of the flow of clean air, and is integrally formed by a frame 5 '. Supported. FIG. 6 is an enlarged view showing the structure of the chemical filter 2 'in this embodiment. As shown,
The chemical filter 2 'has a carbonaceous synthetic adsorbent 11' made of a thermal decomposition product of a granular macroporous synthetic polymer bonded to a porous body 10 'in which a number of voids 12' for allowing gas to permeate are formed. It has a structure supported by the agent 13 '. A carbonaceous synthetic adsorbent consisting of a pyrolyzed product of a macroporous synthetic polymer is obtained by subjecting an addition copolymer of styrene and divinylbenzene to a matrix and subjecting it to a treatment such as sulfonation as necessary. Macroporous (macrop)
orous is obtained by pyrolyzing a synthetic polymer in a non-oxidizing atmosphere and carbonizing it. A typical example of a commercially available product is Amber Soap (trade name of Rohm and Haas Company, USA). The specific structures of the porous body 10 ′, the activated carbon layer 3 ′, and the filter 4 ′ are the same as those of the system 1 described above with reference to FIGS.

[0020]

Next, working effects of the gaseous organic impurity treatment system according to the embodiment of the present invention described above will be described with reference to working examples.

First, in a clean room, clean room air treated with two types of commercially available chemical filters using granular activated carbon and fibrous activated carbon, respectively, and a chemical filter using ion exchange fibers,
FIG. 7 shows the results of measuring the change over time in the contact angle of the wafer surface in a total of four atmospheres of dry air after cooling with liquid nitrogen to remove impurities by condensation. Here, the contact angle measured by dropping ultrapure water on the wafer surface is a method for easily evaluating the degree of organic contamination on the wafer surface. The surface of a silicon wafer or glass with an oxide film free of organic contamination is easily water-compatible, that is, hydrophilic, and has a small contact angle. However, those surfaces contaminated with organic matter are water-repellent, that is, hydrophobic, and have a large contact angle. For example, with respect to a glass substrate surface left in a clean room atmosphere, a measured value of a contact angle by dropping of ultrapure water and an X-ray photoelectron spectroscopy (XPS: X-ray Photo) are used.
It is known that the surface contamination of organic matter measured by electron spectroscopy has a correlation as shown in FIG. Thus, there is an extremely strong correlation between the magnitude of the contact angle of water on the substrate surface and the contamination of the organic substance surface.

The following can be understood from the results shown in FIG. The ion-exchange fiber is originally intended to adsorb and remove water-soluble inorganic impurities, cannot adsorb organic substances, and generates gaseous organic substances. An increase in the contact angle of about 10 ° after one day of standing is observed. On the other hand, the contact angle does not increase in the dry air atmosphere, since almost no gaseous organic matter is contained. The two types of activated carbon filters, which should originally prevent organic surface contamination, increased the contact angle by about 10 ° when left for one day, and showed that there was almost no effect of preventing surface contamination. The reason why the two types of chemical filters using activated carbon are not effective is that surface organic contaminants such as binders, adhesives and sealants are included in the components of the chemical filter. This is because the components were canceled by degassing. If a packed tower is used, there is no such concern if the container of the packed tower is made of metal or the like, but as mentioned above, the packed tower has the disadvantage of high pressure loss (ventilation resistance). It is.

Next, a chemical using natural product type granular activated carbon
In the case of a cull filter, the absorption performance increases as the operating time increases.
There is a problem of breakthrough phenomenon such as lowering. This breakthrough phenomenon
Was examined by experiment. As shown in FIG.
40 mm cross-section^Two4.5m thick
m shaped natural activated carbon with a diameter of 0.5 mm (adsorption
Agent) 31 was charged at a surface wind speed of 3.3 m / sec,
That is, clean room air under the condition of 8 l / min
Was processed. Activated carbon 31 starts at the outlet of the packed tower 30
Generates gaseous organic impurities to remove fine particles
A non-producing Teflon membrane filter 32 was attached.
The upstream and downstream sides of the filling cylinder 30 are made of aluminum
Provided in the chambers 33 and 34.
Glasses 35 and 36 are placed on each side before treatment (activated carbon).
Air before passing through (31) and sky after processing (after passing through activated carbon 31)
Expose the surfaces of the glasses 35 and 36 to the respective atmospheres
Was. Thus, the inside of the chambers 33 and 34 before and after the processing is performed.
Change with time of the contact angle of the glass 35, 36 placed in
I checked it. First, two glass surfaces were exposed to ultraviolet / ozone
Cleaning (UV / O_ThreeCleaning), the organic matter on the surface
Was almost completely removed. Next, the cleanliness immediately after cleaning
The contact angle between the two glass sheets was measured. Measurement
First, two glasses were loaded into the chamber on the upstream and downstream sides of the filling cylinder.
Leave each one for 20 hours and release for 20 hours
Measure the contact angle after installation, and _ThreeCleaning → contact angle
Repeat the measurement → exposure to the target atmosphere for 20 hours → contact angle measurement
I went by returning.

FIG. 10 shows the measurement results of this experiment. FIG.
0 compares the change over time of the contact angle of the glass surface exposed to the clean room air before passing through the natural product type spherical activated carbon and the clean room air after passing through the natural product type spherical activated carbon. The contact angle immediately after washing was 3 °.
This experiment revealed the following. The adsorbing performance of the activated carbon decreases as the ventilation time to the activated carbon increases, and the concentration of gaseous organic substances contained in the air after the passage of the activated carbon also increases. In other words, the contact angle of the glass surface exposed to the treated air on the downstream side for 20 hours increases as the ventilation time to the activated carbon increases. FIG. 10 shows that the use time of the activated carbon until the contact angle of the glass surface exposed to the air after passing through the activated carbon for 20 hours reached 6 ° was 80 hours. Here, it is necessary that the contact angle of the glass surface left for 20 hours after cleaning in a clean room environment be kept at 6 ° or less to prevent the deterioration of the device quality due to gaseous organic impurity contamination. Assuming that FIG. 10 shows that the ratio of the treatment flow rate to the activated carbon weight (8 liters /
min) /0.1 g = (80 m ³ / min) / kg, considering that the clean room air is 80 m long using 1 kg of natural product type spherical activated carbon.
^{When the} treatment is performed at a rate of ³ / min, it means that the necessary conditions for preventing the deterioration of the device quality cannot be satisfied after the air is aerated for 80 hours.

Next, the contact angle of the glass surface exposed to each of the clean room air before passing through the carbonaceous synthetic adsorbent composed of the pyrolyzed product of the macroporous synthetic polymer and the air after passing through the adsorbent is shown. The changes over time were compared. Figure 1 shows the results.
It is shown in FIG. The contact angle immediately after washing was 3 °. In the case of using a carbonaceous synthetic adsorbent consisting of a pyrolysate of a macroporous synthetic polymer, as in the case of using activated carbon,
The adsorption performance decreased with the increase of the aeration time, and the concentration of gaseous organic matter contained in the air after passing through the adsorbent showed a tendency to gradually increase. That is, the contact angle of the glass surface exposed to the treated air on the downstream side for a certain period of time increases with the increase of the ventilation time to the adsorbent. But first, Figure 1
In the case of the natural product type activated carbon shown as 0, the activated carbon usage time was 80 hours until the contact angle of the glass surface exposed to the air after passing through the activated carbon for 20 hours reached 6 °. In the example of the carbonaceous synthetic adsorbent composed of the pyrolyzed product of the macroporous synthetic polymer shown in FIG. 11, the glass surface exposed to air after passing through the adsorbent for 20 hours until the contact angle of the glass surface reaches 6 °. The use time of the adsorbent reached 500 hours. In FIG. 11, the ratio of the processing flow rate to the weight of the adsorbent used is (8 liters / min) /0.1 g = (80 m ³ / m).
(in) / kg. Therefore, 1kg
80m ³ / m of air in a clean room using a carbonaceous synthetic adsorbent consisting of a thermal decomposition product of the macroporous synthetic polymer of
When the treatment is performed at the rate of "in", it means that the necessary condition for preventing the deterioration of the device quality cannot be satisfied after 500 hours of ventilation. In other words, when comparing the service life under the same amount of use and filtration conditions, the carbonaceous synthetic adsorbent composed of the pyrolyzed product of the macroporous synthetic polymer has a lifespan that is about 6 times longer than that of the natural activated carbon. become.

Next, the system described above with reference to FIG. 1 was actually manufactured and its effects were examined. For system A,
A mat having a thickness of 2 to 3 mm made of activated carbon fiber starting from a pitch is provided on the downstream side of the chemical filter formed of the activated carbon-supported polyurethane foam having a thickness of 60 mm, and a HEPA filter or U
An LPA filter was provided. The chemical filter has a structure in which a spherical activated carbon having a diameter of about 0.5 mm is supported on a polyurethane foam having a high porosity structure. A polyurethane adhesive was used to carry the activated carbon. The amount of activated carbon used was 200 g per liter of polyurethane foam. For system B, the HE of system A
All have the same configuration as the system A except that a particulate impurity removal filter made of only a material that does not generate gaseous impurities is used instead of the PA filter or the ULPA filter. For these systems A and B, the change over time in the effect of preventing surface contamination was compared.

For these systems A and B, a surface wind speed of 0.
When the clean room air was ventilated at 5m / s, the pressure loss of the polyurethane foam and mat together was about 5m.
mAq, pressure loss of particulate impurity removal filter is 12m
mAq.

Further, for comparison with the present invention, a system 40 according to the prior art was constructed as shown in FIG. The system 40 has a two-layer structure in which a HEPA or ULPA filter 42 is directly installed on the downstream side of a 60 mm-thick activated carbon-carrying polyurethane foam 41.

The effect of preventing surface contamination by the systems A and B according to the present invention and the system 40 according to the prior art is shown in comparison with FIG. In each case, the surface wind speed was 0.5 m.
Under the condition of / s, the change over time of the contact angle of a silicon wafer having an oxide film immediately after cleaning, which was left downstream of each of the systems A, B, and 40, was measured. In the conventional system 40, the polyurethane adhesive used for supporting activated carbon on the polyurethane foam and degassing from the polyurethane foam itself pass through as they are,
It can be seen that the surface of the silicon wafer left downstream is contaminated. After standing for 3 days, the contact angle on the wafer surface increased from 2.0 ° to 12.1 °. On the other hand, in the systems A and B of the present invention, since the degassing from the polyurethane adhesive or the polyurethane foam itself is adsorbed and removed by the activated carbon fiber mat, the surface of the silicon wafer left downstream is hardly contaminated. . The contact angle on the wafer surface after standing for 3 days is 2.0 ° → 3.
Although a slight increase of about 5% was observed, in System B, the increase hardly increased from 2.0% to 2.1%. In addition,
For reference, FIG. 13 also shows the change over time of the contact angle of a silicon wafer left in the clean room air (upstream of the system) where no processing is performed. The contact angle of the wafer surface left for three days in untreated clean room air increased from 2.0 ° to 32.1 °. Most of the organic matter in the clean room atmosphere that causes surface contamination should be removed by the conventional system 40. The increase in the contact angle of the wafer surface from 2.0 ° to 12.1 ° in three days by the system 40 is due to the adhesive used in the system 40 and degassing from the polyurethane foam. It is considered something.

As described above, the conventional system 40 can remove most of the organic substances that cause surface contamination contained in the clean room atmosphere, but the chemical filter uses polyurethane foam and an adhesive, and a very small amount of debris is removed. There is gas. The degassing concentration from the polyurethane foam and the adhesive is extremely low as compared with the concentration of organic substances contained in the clean room atmosphere and causing surface contamination. For example, assuming that the concentration of the organic substance contained in the clean room atmosphere is several tens of ppb, the degassing concentration is several hundred ppt, which is two orders of magnitude lower. However, it is expected that the effect of the degassing will make it difficult to satisfy the control level of the organic contamination on the wafer surface shown in Table 1 in the future.

In the systems A and B according to the present invention, organic substances contained in the clean room atmosphere that cause surface contamination are adsorbed and removed by a chemical filter provided on the upstream side, and a very small amount of degassing derived from a polyurethane foam or an adhesive. Can be adsorbed and removed by an activated carbon layer provided on the downstream side and having a thickness of only a few mm and not generating gaseous organic impurities. The ratio of the concentration of organic matter in the air to be adsorbed and removed by the chemical filter having a thickness of 60 mm on the upstream side and the activated carbon layer having a thickness of several mm on the downstream side should be much higher in the former than in the latter, for example, 100: Assuming that it is about 1, the life of the activated carbon layer on the downstream side is much longer than the life of the chemical filter on the upstream side. Therefore, it is considered that the life of the entire system is prolonged.

Further, the effect of preventing the surface contamination of the system B using the particulate impurity removal filter composed of only a material that does not generate gaseous impurities on the downstream side shows that the contact angle of the wafer surface after standing for 3 days. Increased little from 2.0 ゜ to 2.1 ゜. This is because, in system A, degassing from the polyurethane-based adhesive is adsorbed and removed by the activated carbon fiber mat 3, but due to degassing from the HEPA filter or ULPA filter disposed downstream of the mat, the gas is removed for three days. The contact angle of the wafer surface after standing is 2.
It increased slightly, from 0 ゜ to 3.5 ゜. On the other hand, in the system B, since the particulate impurity removal filter provided at the most downstream is made of only a material that does not generate gaseous impurities, the contact angle change after leaving for 3 days is 2.0 ° → 2.1.
゜ did not change. That is, almost no surface contamination was observed.

In the system described above with reference to FIG. 5, as shown in FIGS. 10 and 11, when the service life is compared under the same amount of use and filtration conditions, a huge porous synthetic weight is obtained. The carbonaceous synthetic adsorbent composed of the coalesced pyrolysate has a service life that is about six times as long as that of activated carbon based on natural products.
As in the systems A and B described above, the thickness is 60 mm.
At the downstream side of the activated carbon-carrying polyurethane foam, a mat 3 having a thickness of 2 to 3 mm of activated carbon fiber starting from a pitch is provided, and further, at the downstream side, particulate impurities composed only of a material that does not generate gaseous impurities are removed. With respect to the system provided with the filter, a change with time of the surface contamination preventing effect was examined and compared with the systems A and B. Instead of activated carbon, a carbonaceous synthetic adsorbent consisting of a pyrolyzed macroporous synthetic polymer was carried on the polyurethane foam.
Other points are the same as those of the systems A and B described above. The surface wind speed was 0.5 m / s.

The time-dependent change of the contact angle with respect to the silicon wafer having an oxide film immediately after cleaning, which was left downstream of the system, was measured every 20 hours. Contact angle immediately after cleaning is 3
Was ゜. Assuming that the service time until the contact angle of the wafer surface exposed to the downstream air for 20 hours reaches 6 ° is the life, the life of the systems A and B using the natural activated carbon is about 2,500 hours = The life of this system using a carbonaceous synthetic adsorbent consisting of a pyrolysate of a macroporous synthetic polymer is about 16,000 versus 3.5 months.
0 hours = 22 months.

[0035]

According to the present invention, it is possible to provide a system capable of effectively removing gaseous organic impurities so that the pressure loss is small and the future level of controlling the organic contamination on the wafer surface can be satisfied. In particular, according to the present invention, by using a carbonaceous synthetic adsorbent composed of a pyrolyzed product of a macroporous synthetic polymer, it is possible to greatly extend the life of the system. According to the present invention, a semi-finished substrate generated in a semiconductor manufacturing process or the like in a clean room can be kept on standby without causing organic contamination due to an atmosphere on the surface thereof. It is possible to send to the next step without performing or greatly shortening the cleaning time. Therefore, the gaseous organic matter processing system of the present invention can shorten the production time and improve the productivity.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a configuration of a gaseous organic impurity removal system according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a structure of a chemical filter.

FIG. 3 is a perspective view of an activated carbon layer.

FIG. 4 is a sectional view taken along the line AA in FIG. 3;

FIG. 5 is an explanatory view schematically showing a configuration of a system for removing gaseous organic impurities according to another embodiment of the present invention.

FIG. 6 is an enlarged view showing a structure of a chemical filter according to another embodiment of the present invention.

FIG. 7 is a graph showing the results of measuring the change over time in the contact angle of the wafer surface when various chemical fills are used.

FIG. 8 is a graph showing a correlation between a contact angle on a glass substrate surface and organic substance surface contamination.

FIG. 9 is an explanatory diagram of an experimental facility for examining a breakthrough phenomenon of a chemical filter using natural product type granular activated carbon.

FIG. 10 is a graph showing a measurement result of an experiment for examining a breakthrough phenomenon of a chemical filter.

FIG. 11: Change over time in contact angle of a glass surface exposed to clean room air before passing through a carbonaceous synthetic adsorbent composed of a pyrolyzate of a macroporous synthetic polymer and air after passing through the adsorbent. FIG.

FIG. 12 is an explanatory diagram schematically showing a configuration of a system according to the related art.

FIG. 13 is a graph comparing the effect of preventing surface contamination by the system according to the present invention and the system according to the prior art.

[Explanation of symbols]

 Reference Signs List 1 gaseous organic impurity treatment system 2 chemical filter 3 activated carbon layer 4 filter

Claims (7)

[Claims] In a gaseous organic impurity treatment system for removing gaseous organic impurities contained in a gas to generate clean air by permeating the gas, a high porosity capable of allowing the gas to pass therethrough is provided. A chemical filter having a structure in which granular activated carbon is supported on the surface of the void portion of the porous body, an activated carbon layer which is disposed downstream of the chemical filter and does not generate gaseous organic impurities, and which is disposed downstream of the activated carbon layer. And a filter for removing particulate impurities. 2. In a gaseous organic impurity treatment system that removes gaseous organic impurities contained in the gas by permeating the gas to generate clean air, a high porosity that allows the gas to permeate is provided. A chemical filter having a structure in which a carbonaceous synthetic adsorbent composed of a thermal decomposition product of a granular macroporous synthetic polymer is supported on the surface of the voids of the porous body, and particulate impurities disposed downstream of the chemical filter And a filter for removing gas. 3. The gaseous organic impurity treatment system according to claim 2, wherein an activated carbon layer that does not generate gaseous organic impurities is provided between the chemical filter and the particulate impurity removal filter. 4. The gaseous organic impurity treatment according to claim 1, wherein the activated carbon used in the activated carbon layer is any one of granular activated carbon, fibrous activated carbon, and honeycomb activated carbon, or any combination thereof. system. 5. The gaseous organic impurity treatment system according to claim 1, wherein the porous body constituting the chemical filter is a plastic foam. 6. The gaseous organic impurity treatment system according to claim 5, wherein said plastic foam is urethane foam. 7. The gaseous organic substance according to claim 1, wherein said filter for removing particulate impurities is composed of only a material which does not generate gaseous organic impurities. Impurity treatment system.