JP5797564B2 - Chemical filter using acidic additive - Google Patents

Description

  The present invention relates to a chemical filter for removing silanol compounds that may cause exposure failure in an exposure process from the air.

It is known that a disilazane compound such as hexamethyldisilazane ( HMDS ) is used as a photoresist adhesive in the exposure process of the semiconductor manufacturing process. HMDS , for example, is sprayed as a gas on the wafer surface to replace the hydroxyl group on the wafer surface with a trimethylsilanol group, thereby hydrophobizing the wafer surface and improving the adhesion with the resist agent on the wafer surface. . HMDS may hydrolyze and float in the form of trimethylsilanol (TMS) in the form of a gas in the exposure apparatus. However, the suspended TMS may adhere to the lens or the like and cause fogging, which may cause exposure failure.

  Air that has passed through a chemical filter having an adsorbent such as activated carbon is usually supplied into the chamber of the exposure apparatus in which the exposure process is performed. In general, gaseous impurities such as TMS are removed by a chemical filter, so that the inside of the chamber is maintained at a certain level of cleanliness, thereby preventing exposure failure and the like (see, for example, Patent Document 1).

JP 2008-181968 A

  However, TMS is a low molecular weight substance that is difficult to be adsorbed by activated carbon or the like, and is readily desorbed even if it is adsorbed. Therefore, it is difficult to remove it efficiently with a chemical filter having a general adsorbent. Therefore, conventionally, in order to remove the necessary amount of TMS, it has been necessary to make the chemical filter thicker or multi-layered or to use a large amount of activated carbon.

  This invention is made | formed in view of the above problem, and it aims at providing the chemical filter for silanol compound removal which can remove silanol compounds, such as TMS, efficiently.

  The chemical filter for removing silanol compounds according to the present invention includes a large number of adsorbents composed of a porous body, and at least a part of the large number of adsorbents is adsorbed with an acidic substance additive. The silanol compound contained in the air is dimerized and adsorbed by an adsorbent.

  The additive includes an inorganic acid or an organic acid selected from the group consisting of phosphoric acid, phosphonic acid, sulfuric acid, nitrate, sulfate, and organic acid, preferably phosphonic acid, potassium hydrogen sulfate. And selected from the group consisting of aluminum sulfate. On the other hand, the porous body is preferably activated carbon, and the amount of the additive is preferably 12% by weight or less with respect to the porous body. A chemical filter is comprised by the filter base material to which many adsorption agents were fixed, for example. The silanol compound is, for example, trimethylsilanol.

  The filter base material is preferably a foam and the number of cells is preferably 8 to 13 cells / inch. In that case, the average particle diameter of the adsorbent is more preferably 0.55 to 0.65 mm.

  The chemical filter according to the present invention preferably includes a first filter part in which the adsorbent is attached to an adsorbent and a second filter part in which the adsorbent is not attached to the adsorbent. These 1st and 2nd filter parts are arrange | positioned in this order from the upstream along the direction through which air passes.

  The exposure apparatus according to the present invention purifies the internal air by the above-described chemical filter.

  The air purification method according to the present invention includes a silanol compound in a chemical filter provided with a large number of adsorbents composed of a porous body, and at least a part of the large number of adsorbents is adsorbed with an acidic substance additive. The silanol compound is dimerized by passing air containing the dimer, and the dimer is adsorbed by an adsorbent.

  In the present invention, since the silanol compound is made into a dimer that is not easily desorbed from the chemical filter and is adsorbed by the adsorbent, the removal efficiency of the silanol compound of the chemical filter can be improved.

It is the schematic which shows the exposure apparatus with which the chemical filter of this invention is applied. It is an enlarged view which shows the chemical filter which concerns on the 1st Embodiment of this invention. It is a perspective view which shows the chemical filter which concerns on 2nd Embodiment. It is a perspective view which shows the chemical filter which concerns on the modification of 2nd Embodiment. It is a schematic diagram which shows the column for implementing ventilation | gas_flow experiment. It is a schematic diagram which shows the column for implementing ventilation | gas_flow experiment 2-4. It is a schematic diagram which shows typically the test apparatus used by the ventilation test 5. FIG.

DESCRIPTION OF SYMBOLS 10 Exposure apparatus 15 Internal chemical filter 50 Filter base material 51 Adsorbent 66 1st chemical filter (1st filter part)
67 2nd chemical filter (2nd filter part)
70A upstream part (first filter part)
70B Downstream part (second filter part)

Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a schematic view showing an exposure apparatus to which a chemical filter according to the first embodiment of the present invention is applied. As shown in FIG. 1, the exposure apparatus 10 has a structure in which an internal chamber 12 and an air circulation path 13 are provided inside an external chamber 11, and an exposure main body 20 is provided inside the internal chamber 12. Be placed. The air circulation path 13 is a passage for circulating the air inside the internal chamber 12. Inside the air circulation path 13, there are provided a temperature and humidity control device 14 for keeping the temperature and humidity of the air inside the internal chamber 12 constant, and an internal chemical filter 15 for purifying the air in the internal chamber 12.

  The exposure main body 20 includes an illumination optical system 21, a reticle 22, a projection optical system 23, and a wafer stage 24, and a wafer W is placed on the wafer stage 24. The wafer W has a surface coated with a photoresist agent after the surface has been hydrophobized by a photoresist adhesive which is a disilazane compound represented by the following general formula (1).

R ₃ SiNHSiR ₃ (1)
In the formula (1), R is an alkyl group having 1 to 3 carbon atoms such as methyl and ethyl, but a part of R may be a hydrogen atom, or a halogen atom such as a fluorine atom or a chlorine atom. As the disilazane compound, hexamethyldisilazane ( HMDS ) in which R is all methyl in the above formula (1) is generally used.

  The illumination optical system 21 includes a relay lens system, a condenser lens, and the like, and makes the laser beam emitted from the light source 26 provided outside the external chamber 11 enter the reticle 22. The reticle 22 is a photomask having a predetermined mask pattern, and the mask pattern is imaged on the wafer W arranged on the wafer stage 24 via the projection optical system 23, and the wafer W is subjected to exposure processing. Done.

  A fan (not shown) is provided inside the air circulation path 13 and the like, and the air inside the external chamber 11 is circulated along the fixed path S by the fan. Specifically, the air in the air circulation path 13 is supplied into the internal chamber 12 through the internal supply port 16, circulates in the internal chamber 12, and is discharged to the air circulation path 13 through the internal discharge port 17. Is done. The air discharged from the internal discharge port 17 is supplied to the inside of the internal chamber 12 through the internal chemical filter 15 and the temperature control device 14 and again through the internal supply port 16 in the air circulation path 13. . A part of the air in the internal chamber 12 is exhausted to the outside through the local discharge port 18, and the external air is supplied to the inside of the air circulation path 13 through the external supply port 19.

  The temperature and humidity control device 14 is disposed upstream of the internal supply port 16, and the air supplied from the air circulation path 13 to the inside of the internal chamber 12 is adjusted to a constant humidity and a constant temperature by the temperature control device 14. It is a thing. An external chemical filter 25 is disposed upstream of the external supply port 19, and air from the outside is supplied to the air circulation path 13 after removing gaseous pollutants by the external chemical filter 25. .

  As shown in FIG. 2, the internal chemical filter 15 provided in the air circulation path 13 has a three-dimensional network skeleton structure made of a foamed material such as polyurethane foam, for example, a filter base material having a mat shape. 50, innumerable adsorbents 51 are fixed by a known binder. In addition, as the filter base material 50, the fibrous base material and honeycomb structure which are comprised from an organic fiber or an inorganic fiber may be used instead of a foam. The internal chemical filter 15 in the present embodiment is a silanol compound removing chemical filter capable of efficiently removing a silanol compound described later by having the following configuration.

  The adsorbent 51 of the internal chemical filter 15 is obtained by attaching an acidic substance additive to the surface of a porous body such as a crushed shape, a powder shape, or a particle shape (for example, a bead shape). Examples of the porous body used for the adsorbent 51 include those capable of adsorbing gaseous organic substances such as activated carbon, silica, zeolite, alumina, and porous glass by physical adsorption. Among these, activated carbon is preferable. This is because activated carbon easily adsorbs a silanol compound or a disiloxane compound described later.

As the additive, an acidic substance selected from the group consisting of inorganic acids and organic acids is used. Examples of these inorganic acids and organic acids include copper (II) sulfate (CuSO ₄ ), iron (II) sulfate (FeSO ₄ ), iron (III) sulfate (Fe ₂ (SO ₄ ) ₃ ), aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), sulfates exemplified by potassium hydrogen sulfate (KHSO ₄ ), iron (III) nitrate (Fe (NO ₃ ) ₃ ), silver nitrate (AgNO ₃ ), aluminum nitrate (Al (NO ₃ )) ₃ ), nitrates exemplified by manganese nitrate (II) (Mn (NO ₃ ) ₂ ), inorganic acids such as sulfuric acid, phosphoric acid and phosphonic acid, and organic acids such as citric acid. In these, in order to make the silanol compound mentioned later easy to dimerize, it is preferable to use phosphonic acid, aluminum sulfate, or potassium hydrogen sulfate which is a hydrogen sulfate metal salt, and potassium hydrogen sulfate is especially preferable.

  The adsorbent 51 is obtained by, for example, immersing the porous body in an aqueous solution of an additive or spraying the aqueous solution of the additive on the porous body to adhere the aqueous solution to the surface of the porous body and then drying by heating. It is obtained by supporting an adsorbent on the adsorbent 51. The amount of the additive added to the porous body is preferably 12% by weight or less, particularly preferably 4 to 9% by weight, based on the porous body (100% by weight). If the amount of the additive is excessively increased, the surface of the porous body is blocked by the additive, and the gas adsorption capacity of the porous body is reduced. As a result, the removal ability of the silanol compound is reduced, and the amount of the adhesive is added. If the amount is too small, the efficiency of dimerizing the silanol compound by the adsorbent 51 is lowered, so the amount of attachment is preferably in the above range.

  The foam such as polyurethane foam used as the filter substrate is not particularly limited, but the number of cells is preferably 8 to 13 / inch. When the number of cells is less than 8 cells / inch, a sufficient amount of activated carbon does not adhere to the foam, and the efficiency of dimerizing the silanol compound and the adsorption performance decrease. If the number of cells is 14 cells / inch or more, the voids are too small, the efficiency of dimerization becomes low, the adsorbent becomes difficult to adhere to the foam, and the pressure loss may increase. is there. The number of cells is particularly preferably 10 to 11 cells / inch in order to improve the dimerization efficiency and the removal efficiency.

  Further, when the porous body is a bead-shaped porous body made of activated carbon or the like, the number of cells is set to 7 to 13 / inch, and the average particle diameter of the porous body is set to 0.55 to 0.00. By setting the thickness to about 65 mm, the adsorbent adhesion amount and the gap are kept in a good balance, and both the adsorption performance and the dimerization rate can be sufficiently increased. The average particle size is measured by a dry sieving method according to JIS K 1474-5.4. The number of cells is a value obtained by visually measuring the number of cells per inch.

As described above, the wafer W is subjected to a hydrophobization process by the photoresist adhesive agent composed of a disilazane compound, and the interior of the chamber 12 is kept at a constant relative humidity. Therefore, the silanol compound of the chemical formula (2) generated by the hydrolysis reaction of the disilazane compound (see the reaction formula (2) ′) is suspended inside the internal chamber 12 and circulates along the fixed path S. Air includes a silanol compound.
R ₃ SiNHSiR ₃ + 2H ₂ O → 2R ₃ SiOH + NH ₃ (2) ′

R ₃ SiOH (2)
The silanol compound has only one SiOH group as shown in Formula (2). In the formula (2), R is an alkyl group having 1 to 3 carbon atoms such as methyl and ethyl, but a part of R may be a hydrogen atom, or a halogen atom such as a fluorine atom or a chlorine atom. The silanol compound is generally a decomposition product of HMDS , and is trimethylsilanol (TMS) in which R is all methyl in the formula (2).

  The silanol compound is dimerized by dehydration condensation as shown in the following formula (3). This dehydration condensation reaction hardly occurs at a low concentration of silanol compound as in the exposure apparatus 10, but if there is an adsorbent to which the above-mentioned adsorbent is adsorbed, the adsorbing action of the adsorbent and It tends to occur due to the acid catalysis of the additive. Therefore, at least a part of the silanol compound (usually about half or more) is dimerized when passing through the internal chemical filter 15 and chemically changed to a disiloxane compound that is a dimer. Since the disiloxane compound that is a dimer has a molecular weight larger than that of the silanol compound, it is more easily adsorbed by the porous body of the internal chemical filter 15 than the silanol compound, and is less likely to desorb after being adsorbed.

  That is, the internal chemical filter 15 can adsorb the silanol compound to the adsorbent 51 efficiently by positively dimerizing the silanol compound with the additive. Thus, in this embodiment, since the silanol compound can be efficiently removed by the adsorbent 51, the life of the internal chemical filter 15 can be extended.

2R ₃ SiOH → R ₃ SiOSiR ₃ + H ₂ O (3)
In the formula (3), the disiloxane compound (R ₃ SiOSiR ₃ ) is generally hexamethyldisiloxane which is a dimer of TMS.

  The external chemical filter 25 may be a chemical filter having the same configuration as the internal chemical filter 15, but a chemical in which a porous body such as activated carbon to which no additive is attached is fixed to the filter base material. It may be a filter. Of course, the internal chemical filter 15 also removes gaseous impurities other than the silanol compound and its dimer by the adsorbent 51. Further, another type of air filter may be further provided on the path S.

  FIG. 3 shows the structure of a chemical filter according to the second embodiment of the present invention. In the first embodiment, the internal chemical filter 15 is constituted by a single chemical filter. In the second embodiment, the internal chemical filter 65 includes the first and second chemical filters as shown in FIG. The chemical filters 66 and 67 are overlapped. The first and second chemical filters 66 and 67 are arranged in this order from the upstream side along the direction S ′ through which air passes.

  In this case, the first chemical filter 66 has the same configuration as the internal chemical filter 15 of the first embodiment, and an infinite number of adsorbents in which an acidic substance additive is attached to the filter base 50. Is fixed. On the other hand, the second chemical filter 67 is obtained by fixing an infinite number of adsorbents to which an acidic substance additive is not attached to the filter substrate 50.

  In this embodiment, the removal rate of the silanol compound is further improved by providing two chemical filters. The second chemical filter 67 is not attached because the concentration of the silanol compound in the inflowing air is extremely low and the dimerization effect is low even if an acid-adsorbed adsorbent is used.

  Further, the first chemical filter 66 is likely to generate outgas due to the adsorbent adhering to the adsorbent, but such outgas is adsorbed and removed by the second chemical filter 67. Therefore, in the first chemical filter 66, it is possible to effectively prevent the outgas resulting from the additive from entering the internal chamber 12.

  Furthermore, the first and second chemical filters 66 and 67 in the second embodiment are configured by attaching an infinite number of adsorbents to the separate filter base materials 50 and 50, respectively, as shown in FIG. Alternatively, the chemical filter 70 may be configured from one filter base material 50. In this case, the adsorbent to which the additive is attached is fixed to the upstream portion (upstream portion 70A) of the chemical filter 70, and the adsorbent to which the additive is not attached is fixed to the downstream portion (downstream portion 70B). Is done.

  In the first embodiment, both the activated carbon to which the additive is attached and the activated carbon to which the additive is not attached may be mixed and fixed to the filter substrate 50. Further, in the case where the first and second chemical filters are stacked as in the second embodiment, activated carbon to which an additive is attached may be fixed to any of these filters.

  In the first and second embodiments, each chemical filter may not be one in which an adsorbent is fixed to a filter base material, for example, a container or case filled with an adsorbent. Also good. For example, in the second embodiment, the first chemical filter is assumed to be filled with an adsorbent with an additive in a container or case, and the second chemical filter is attached with an additive. A non-adsorbent may be fixed to the filter substrate.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the configurations of the following examples.

[Ventilation test 1]
In the ventilation experiment 1, as shown in FIG. 5, a column 80 was prepared in which six layers of chemical filters 83A to 83F were placed inside. The chemical filters 83A to 83F are Gigasorb L (trade name, manufactured by NITTA CORPORATION), which is constituted by adhering activated carbon with no additive to urethane foam with 7 cells / inch, and having a diameter of 19 mm, A cylinder with a height of 20 mm was used. On the side of the air outlet 82 of the column 80, there are a valve 84 for adjusting the flow rate of air, a flow meter 85 for measuring the flow rate of air vented to the column 80, and a pump 86 for ventilating the column 80 with air. Connected. The most upstream chemical filter 83A was used as a TMS source with about 450 g / m ² of TMS adhered thereto. In this aeration test and the following aeration tests 2 to 6, beaded activated carbon having an average particle diameter of 0.64 mm was used as activated carbon.

  The column 80 was aerated with air conditioned at 23 ° C. for 240 hours at 10.2 liters / minute (surface wind speed 0.6 m / second). A part of TMS was dimerized to hexamethyldisiloxane (hereinafter abbreviated as “D2”), and TMS or D2 was desorbed from the chemical filter 83A by air ventilation and flowed downstream.

  After the ventilation, the chemical filters 83A to 83F are put in 20 ml of acetone, and gaseous organic substances adsorbed on each filter are extracted by ultrasonic vibration over 2 hours. Each of the filters 83A to 83F is extracted by GC-FID. The amount of TMS and D2 adsorbed on was measured. Further, regarding the chemical filters 83A to 83F before ventilation (0 hour), the weights of TMS and D2 were similarly measured as blanks. Table 1 shows the measured values in each layer and the ratio (wt%) of the adsorption amount of each layer when the total adsorption amount is 100 wt% for TMS and D2.

The measurement conditions of GC-FID are as follows.
GC-FID: manufactured by Shimadzu Corporation, GC-2010
Column: Inert Cap 1MS Inner Diameter 0.25mm Length 60m
Column temperature: maintained at 40 ° C. for 5 minutes, then heated to 280 ° C. at 10 ° C./min. Thereafter, maintained at 280 ° C. for 21 minutes.
Carrier gas: He Column flow rate: 1.16 ml / min Injection volume: 1.0 μl Measurement time: 50 minutes

  As is clear from the results in Table 1, most of the TMS was desorbed from the first-layer chemical filter, and the desorbed TMS was most adsorbed by the third-layer chemical filter. On the other hand, most of D2 was retained by the first-layer chemical filter, and most of D2 was adsorbed by the second-layer filter. That is, TMS is difficult to be adsorbed by the chemical filter and is easily desorbed once adsorbed, but the dimer (D2) is easily adsorbed to the chemical filter, and once adsorbed, it is difficult to desorb from the filter. Understandable.

[Ventilation experiment 2]
In the ventilation experiment 2, as shown in FIG. 6, a column 100 in which first to seventh tube portions 101 to 107 are connected in this order was prepared. The 1st pipe part 101 comprised the air inlet, and the 7th pipe part 107 comprised the air discharge port. A valve 108 that adjusts the flow rate of air, a flow meter 109 that measures the flow rate of air that is vented to the column 100, and a pump 110 that ventilates the column 100 were connected to the air outlet. In the column 100, a chemical filter 111 is disposed inside the second tube portion 102. The chemical filter 111 had TMS attached and was used as a TMS generation source.

The 4th pipe part 104 filled the inside with the adsorption agent 112, and comprised the 1st chemical filter. In Examples 1 to 14 and Comparative Examples 1 and 2, as the adsorbent 112, an activated carbon obtained by adding the additives shown in Table 2 to the activated carbon was used. Comparative Example 3 was carried out in the same manner as in Examples 1 to 14 except that the additive was not attached. In Comparative Example 4, as the adsorbent 112, a bead-shaped acidic ion exchange resin for Gigasorb R (manufactured by Nitta Corporation) was used.

Six layers of chemical filters 113 </ b> A to 113 </ b> F are stacked inside the sixth pipe portion 106, and the adsorption layer 113 is provided as a second chemical filter. As the chemical filters 111 and 113A to 113F in the ventilation test 2, the same chemical filters as those used in the ventilation test 1 were used.

  Clean air having a temperature of 25 ° C. and a relative humidity of 55% was passed through the column 100 by suction of the pump 110 at a surface wind speed of 0.6 m / sec (10.2 liter / min). By this ventilation, TMS was desorbed from the chemical filter 111, and air containing TMS was flowed downstream from the second pipe portion 102. Aeration was performed for 24 hours with an aeration concentration of TMS of 2000 to 3000 ppb. TMS partially changed to D2 due to the acid catalysis of the adsorbent. After the ventilation, the weight of TMS and D2 adsorbed on the adsorbent 112 and the filters 113A to 113F is measured in the same manner as in the aeration experiment 1, and the adsorbent 112 and the adsorbed layer 113 are adsorbed from the measured values. The total of each of TMS and D2 thus obtained was determined, and the ratio (% by weight) of TMS and D2 was calculated. Table 2 shows the calculation results.

なお、実施例１〜１１、１３、１４及び比較例１〜２において、添着剤の活性炭に対する添着量は６重量％であった。また、実施例１２では、リン酸の活性炭に対する添着量は１８重量％であった。

In Examples 1 to 11, 13, 14 and Comparative Examples 1 to 2, the amount of the additive to the activated carbon was 6% by weight. In Example 12, the amount of phosphoric acid attached to the activated carbon was 18% by weight.

[Ventilation experiment 3]
Next, among the above examples, Examples 4, 7, 9, 10 to 13 and Comparative Examples 3 and 4 are as shown in Table 3 in order to verify the effect closer to the actual use environment. Aeration experiment 3 was performed with a lower TMS aeration concentration (below 51 ppb). In aeration experiment 3, the ratio of TMS and D2 adsorbed on the adsorption layer 113 after 120 hours of aeration was measured. The results are shown in Table 3. In the aeration experiment 3, the conditions other than the aeration time and the aeration concentration were the same as those in the aeration experiment 2.

[Ventilation experiment 4]
Next, for Examples 7, 9, and 13 in which the rate of change to D2 was high in the ventilation experiment 3, the amount of the additive was 3% by weight, 9% by weight, and 12% by weight (however, Example 7 was 9% by weight) The experiment similar to the ventilation experiment 3 was performed. The results are shown in Table 4. In Table 4, only the ratio (%) of D2 is shown.

  As is clear from the aeration experiments 2 and 3, Examples 1 to 13 using an acidic substance as an additive are compared with Comparative Examples 1 to 3 using an unattached activated carbon and a neutral substance as an additive. The rate of change was high. In Comparative Example 4 using an acidic ion exchange resin as an adsorbent, the rate of change to D2 was good in the aeration experiment 2, but the rate of change to D2 was significantly low in the aeration experiment 3. From this result, it is presumed that the acidic ion exchange resin has a low effect of dimerizing the silanol compound under a practical use environment. From the results of the aeration experiment 3, aluminum sulfate, potassium hydrogen sulfate, and phosphonic acid are excellent in the effect of dimerizing the silanol compound. From the aeration experiment 4, the addition amount of the additive is preferably 12% by weight or less, preferably It can be understood that it may be about 4 to 9% by weight.

[Ventilation experiment 5]
Example A and Comparative Examples B and C were carried out by aeration test 5 using the test apparatus shown in FIG. 7, and the removal performance of the chemical filter according to the present invention was confirmed.
[Example A]
As shown in FIG. 7, a column 120 to which the first and second pipe portions 121 and 122 were connected from the air inflow side was prepared. As in the ventilation test 1, a valve 123, a flow meter 124, and a pump 125 were connected to the discharge side of the column 120. A TMS generation source 135 and a chemical filter 136 arranged in the constant temperature and humidity chamber 137 were connected to the air inflow side of the column 120. The TMS generation source 135 is configured by disposing an inner container 138 having an opening at the top and containing 3 ml of liquid TMS inside the outer container 139 forming a part of the ventilation path.

Inside the first pipe part 121, a single-layer chemical filter formed by adhering activated carbon with potassium hydrogen sulfate adsorbed as an adsorbent to urethane foam having 13 cells / inch is disposed as the first filter 131. did. In this adsorbent, potassium hydrogen sulfate was impregnated at 8% by weight with respect to the activated carbon. The shape and size of the first filter 131 were the same as the filters 83A to 83E in the ventilation test 1. In addition, the adsorbent was applied to a urethane foam having a binder attached to the entire body, and the adsorbent was uniformly fixed to the entire foam. Inside the second tube section 122, overlapping 10 layers similar Gigasobu L to that used in the filter 83A~83E ventilation test 1, it was provided a second filter 132.

  The air inside the constant temperature and humidity chamber 137 is maintained at a temperature of 23 ° C. and a relative humidity of 50%. Gas components in the air are removed by the chemical filter 136 to form clean air, and the TMS generation source 135 is vaporized. The TMS was contained in a certain ratio and then sent to the column 120. In the column 120, TMS contained in the air was partially dimerized into D2 and then collected by the first and second chemical filters 131 and 132. Aeration was performed for 338 hours at 10.2 L / min and a surface wind speed of 0.6 m / sec.

  After the ventilation, the amounts of TMS and D2 adsorbed on each layer of the filter 131 and the filter 132 were measured in the same manner as in the ventilation test 1. In Table 5, the measured value of the adsorption amount in each layer of TMS and D2 and the total adsorption amount of TMS + D2 in each layer are shown. Further, the ratio of the total adsorption amount in each layer to the adsorption amount of the entire column was shown as% as an adsorption ratio, and D2 / (TMS + D2) in each layer was shown as% as the D2 change rate.

[Comparative Example A]
The same procedure as in Example A was performed, except that activated carbon with no additive was used as the porous body in the first chemical filter 131.

[Comparative Example B]
The same operation as in Comparative Example A was performed, except that the urethane foam in the first chemical filter was 7 cells / inch.

  As is apparent from the results of the aeration test 5, in Example A using an acidic substance (potassium hydrogen sulfate) as an additive, the D2 change rate is high, and the adsorption rate reaches 90% only with the first chemical filter. The removal performance was high. On the other hand, in Comparative Examples A and B using activated carbon with no additive added, the D2 change rate is low and the total adsorption ratio reaches 90% in the 5th to 6th layers of the second chemical filter. The removal performance of the silanol compound was not sufficient.

[Air permeability test 6]
Next, Examples B to F were carried out by aeration test 6 to confirm the difference in removal performance due to the difference in the number of cells. In the ventilation test 6, in addition to the internal container 138 containing TMS, two internal containers (not shown) are arranged inside the external container 139, and 5 ml of toluene and 10 ml of tetradecane are placed in each of the internal containers. A test apparatus similar to the aeration test 5 was used except for the added points. That is, in the aeration test 6, the air sent to the column 120 was made to contain vaporized toluene and tetradecane in addition to TMS. Moreover, while using the following as a 1st chemical filter, it implemented on the conditions similar to the ventilation | gas_flow test 5 except the point which set the ventilation | gas_flowing time to 168 hours.

  In each of Examples B, C, D, and E, Example A is the same as Example A except that urethane foams having 6 cells / inch, 8 cells / inch, 10 cells / inch, and 11 cells / inch were used. A similar chemical filter was used as the first chemical filter 131. The first chemical filter 131 of Example F was the same as Example A, and had 13 cells / inch. The adsorbent adhering amounts of Examples B, C, D, E, and F were 745 g, 900 g, 1130 g, 1120 g, and 980 g, respectively, per urethane foam 600 mm × 300 mm. The results of Examples B to F are shown in Tables 8 to 12.

  As is clear from the above results, when the number of cells was reduced as in Example B, the amount of adsorbent was reduced, the removal efficiency was lowered, and the D2 change rate was also lowered. On the other hand, in Examples C to F in which the number of cells was 8, 10, 11, 13 / inch, the D2 change rate was relatively good and the removal efficiency was also good.

Claims (8)

A large number of adsorbents composed of a porous material, and at least a part of the large number of adsorbents is adsorbed with an additive of an acidic substance, and a silanol compound contained in the air is Quantified and adsorbed by the adsorbent,
The amount of the additive is 4 to 9% by weight based on the porous body,
Comprising a filter substrate to which the multiple adsorbents are fixed;
The porous body is activated carbon ,
The silanol compound removing chemical filter , wherein the additive includes a material selected from the group consisting of phosphonic acid, nitrate, sulfate, and organic acid . A first filter portion in which the adsorbent is attached to the adsorbent; and a second filter portion in which the adsorbent is not attached to the adsorbent. The first and second filter portions are: The chemical filter according to claim 1 , wherein the chemical filter is disposed in this order from the upstream side along a direction in which air passes. The chemical filter according to claim 1 or 2 , wherein the additive includes a material selected from the group consisting of phosphonic acid, potassium hydrogen sulfate, and aluminum sulfate. The chemical filter according to any one of claims 1 to 3 , wherein the filter base is a foam and the number of cells is 8 to 13 cells / inch. 5. The chemical filter according to claim 1, wherein the adsorbent has an average particle size of 0.55 to 0.65 mm. The chemical filter according to claim 1 , wherein the silanol compound is trimethylsilanol. An exposure apparatus, wherein the internal air is purified by the chemical filter according to claim 1 . While including a large number of adsorbents composed of a porous body, at least a part of the large number of adsorbents is allowed to pass air containing a silanol compound through a chemical filter in which an acidic substance additive is attached, The silanol compound is dimerized and adsorbed by the adsorbent, and the adhering amount of the adhering agent is 4 to 9% by weight with respect to the porous body, and the filter base on which the large number of adsorbents are fixed. The filter substrate is a foam, the porous body is activated carbon, and the additive includes a material selected from the group consisting of phosphonic acid, nitrate, sulfate, and organic acid. An air purification method characterized by the above.

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