JPH08318131A - Waste gas treating agent and treating method - Google Patents

Abstract

PURPOSE: To treat a waste gas contg. silane-base gas from a semiconductor producing device while suppressing the evolution of heat and to remove the silane-base gas by using hydrotalcite having a specified structure and a precursor having an amorphous structure as treating agents. CONSTITUTION: A treating agent 5 to be used consists essentially of hydrotalcite shown by (M<3+> XM<2+> 1- X(OH)2 X<+> (A<n-> x/nmH2 O)X<-> and a precursor having an amorphous structure, where M<3+> is a trivalent metal ion, M<2+> is bivalent-metal ion, and A<n-> is an n-valent anion. The silane-base gas in the waste gas from a semiconductor producing device is brought into contact with the solid treating agent 5 packed in a column 1 attached to the discharge port of the device. Consequently, the silane concn. in the waste gas is decreased to <=0.5ppm, preferably to <=0.1ppm, while suppressing heat evolution. Meanwhile, M<3+> is Al<3+> , Fe<3+> , or Cr<3+> , M<2+> is Mg<2+> , Mn<2+> or Cu<2+> , and A<n-> is OH<-> , Cl<-> , NO3 <-> , CO3 <2-> or SO4 <2-> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treating agent and a treating method for highly treating exhaust gas containing a silane-based gas.
More specifically, the present invention relates to a treating agent and a treating method for performing advanced treatment by bringing the silane-based gas for semiconductor production into contact with exhaust gas.

[0002]

2. Description of the Related Art The development of today's semiconductor industry is remarkable.
VLSI, compound semiconductors, amorphous solar cells, etc.
Indeed, technological innovation is advancing day by day, and the amount of gas used for semiconductor manufacturing is also increasing. Among such semiconductor manufacturing gases, especially monosilane (SiH ₄ ) and disilane (Si
Silane-based gas such as ₂ H ₆ ), trisilane (Si ₃ H ₈ ), etc. is formed by a method such as thermal decomposition, photo-decomposition, plasma decomposition or the like into single crystal silicon, polycrystalline silicon, amorphous silicon, silicon oxide film, silicon nitride. It is an essential gas for the formation of films. However, such a gas is highly reactive and spontaneously igniting, and in the case of monosilane, for example, it is highly toxic such as causing severe respiratory irritation by absorption, and if released in high concentration to the outside of the human body, There are immeasurable negative effects on the natural environment. Therefore, in Japan, regulations on the concentration of silane-based gas in exhaust gas in the semiconductor industry are being strengthened for the purpose of maintaining a good working environment and preventing destruction of the natural environment. Moreover, in the United States, severe regulations are being enforced, such as the "American Council for Industrial Health Supervisors" setting the working environment concentration of monosilane to 0.5 ppm. In general, for manufacturing semiconductors, a gas obtained by diluting a silane-based gas with a gas such as hydrogen, helium, argon, or nitrogen from several% to several tens of% is often used, but sometimes a 100% silane-based gas that is not diluted is used. Gas may also be used.

Such a method for safely detoxifying a silane-based gas is treated by an apparatus devised to mix a gas containing a high concentration of the silane-based gas with air and burned, or a hydroxylation. Method of contact with aqueous alkali solution
6-84619, 57-94323) and the like, a method is known in which the silane-based gas concentration is reduced as much as possible and then released into the atmosphere.

In recent years, a column has been attached to the exhaust port,
A method of filling this with a metal oxide as a treating agent (Japanese Patent Publication No. 4-19886) and a method of filling basic copper carbonate have also been adopted. However, in the method of using such a treating agent, there is a problem that heat is generated while the silane-based gas is passed through the treating agent, or after the aeration treatment, the treating agent is heated and ignited when exposed to the atmosphere. Has occurred. Therefore, it is safe in handling, and the silane-based gas in the exhaust gas is at least 0.5 ppm,
It is expected to develop a technique for completely removing the metal, preferably up to about 0.1 ppm.

[0005]

That is, an object of the present invention is to install a silane-based gas in the exhaust gas of a semiconductor manufacturing apparatus at a discharge port equipped with a column, and to fill it with a treating agent to ensure safe and almost complete treatment. It is to provide a treatment method for removing a silane-based gas. The gist is to reduce the heat generated when the silane-based gas is passed through the treatment agent or after the treatment agent is exposed to the atmosphere, and to include the silane-based gas from the semiconductor manufacturing equipment. It is an object of the present invention to provide an advanced treatment agent and a treatment method for exhaust gas having a silane-based concentration in the exhaust gas of at least 0.5 ppm or less, preferably 0.1 ppm or less, that is, substantially free of silane-based gas.

[0006]

According to the present invention, exhaust gas containing silane-based gas from a semiconductor manufacturing apparatus is filled in a column with a specific processing agent to reduce heat generation as compared with the conventional method. To remove. That is, in the present invention, among the precursors having a general formula represented by the formula 2 and having a hydrotalcite and an amorphous structure, M ³⁺ is a trivalent metal ion, M ²⁺ is a divalent metal ion and A ^n−. Of exhaust gas containing a silane-based gas whose main component is an n-valent anion and gas-solid contact with the exhaust gas containing the silane-based gas discharged from the semiconductor device. Regarding the method.

^{Embedded image} [M ³⁺ _X M ²⁺ _1-X (OH) ₂ ]
^{X +} [A ^n- _{X / n} mH ₂ O] ^X-

Hereinafter, the present invention will be described in detail. Hydrotalcite having a crystal structure, which is one of the main components of the treating agent of the present invention, is [M ³⁺ _X M ²⁺ _1-X (OH) ₂ ] ^{X +.}
[A ⁿ⁻ _{X / n} mH ₂ O] ^X− , where M ³⁺ is a trivalent metal ion, M ²⁺ is a divalent metal ion, and A ⁿ⁻ is a component mainly composed of an n-valent anion. Most effective. Among them, Al ³⁺ in which M ³⁺ is a trivalent metal ion,
Fe ³⁺ or Cr ³⁺ , Mg ²⁺ in which M ²⁺ is a divalent metal ion, Mn ²⁺ or Cu ²⁺ , and OH ⁻ , Cl ⁻ , NO ₃ ⁻ , CO ₃ ^{2− in} which ^{An −} is an anion.
Alternatively, SO ₄ ²⁻ is preferable. Furthermore, among such hydrotalcites, Al ₂ Mg ₆ (OH) ₁₆ (CO
₃ ) .4H ₂ O and Al ₃ Cu ₇ (OH) ₂₀ (CO ₃ )
_1.5 · 6H ₂ O, Al ₂ Mn ₆ (OH) ₁₆ (C
O ₃ ) .4H ₂ O is most preferably used. The general production method of hydrotalcite with these crystal structures is:
For example, when Cu is used for M ²⁺ , a known amount of 0.16 ≦ X ≦ 0.33 of copper nitrate and aluminum nitrate is mixed with an aqueous solution of sodium carbonate to obtain a slurry pH.
Is adjusted to be 6 to 7. Furthermore, after aging at a temperature of 80 to 90 ° C., a layered compound obtained by filtering and drying, that is, a powder having a hydrotalcite structure can be obtained.

The other treating agent of the present invention is a precursor having the same composition as the above and having an amorphous structure. The precursor having an amorphous structure can be obtained by removing the aging operation from the above hydrotalcite production method. These are also produced by the manufacturing method described above.
Further, even those which are commercially available can be used. Further, in the present invention, a mixture of a powder having a hydrotalcite structure and a powder having an amorphous structure as a precursor thereof may be used. In addition, as unreacted products, Al
Even if a small amount of (OH) ₃ or an alkaline component as a raw material is contained, there is no problem in its effect.

The treating agent of the present invention is mainly composed of the above-mentioned components, and when an actual treating operation is carried out, this is used as a packed bed, and exhaust gas containing a silane gas is contained in the packed bed. Aeration is performed. In this case, it is desirable that the particles of the hydrotalcite as a treating agent be fine and have a specific surface area (SA) of 1 m ² / g or more to improve the gas-solid contact ability with the silane-based gas. These may be used as they are, but may be pulverized into finer particles, kneaded with a desired composition, or molded into an appropriate shape. Further, it may be supported on, for example, Al ₂ O ₃ , SiO ₂ , zeolite, etc. which are generally known as carriers. The silane-based gas of the present invention means monosilane (SiH ₄ ), disilane (Si ₂ H ₆ ), trisilane (Si ₃ H ₈ ), phosphine (PH ₃ ), arsine (AsH ₃ ), diborane (B). ₂ H ₆ ), etc., and a gaseous metal hydride compound.

Further, in order to enhance the exhaust gas treating ability of the treating agent, a higher treating temperature is more effective than usual. Therefore, when operating in a packed bed, it is preferable to feed the exhaust gas while heating the packed bed. However, some of the treating agents of the present invention do not require such heating at all and can sufficiently perform the exhaust gas removing function even at room temperature, and the concentration of the silane-based exhaust gas to be treated and the desired removal Depending on the rate, it is not absolutely necessary. Incidentally, as shown in Examples, in the treatment with the treatment agent mainly composed of hydrotalcite in the present invention, the concentration of silane-based gas in the exhaust gas is 0.1 ppm or less,
That is, it can be processed below the detection limit.

When the treating agent of the present invention is used, for example, when it is operated as a packed bed, a packed bed of one series is sufficient, but an operating point of view such as regeneration or replacement of the packing material. Therefore, it is desirable to use a plurality of parallel methods and use them as a processing layer and a reprocessing layer, respectively, by switching between them. In actual semiconductor manufacturing, since arsenic, boron, phosphorus, etc. are often doped in a silicon film with silane, disilane, or trisilane gas, silane,
Exhaust gas containing disilane, trisilane gas and dopants arsine, phosphine, diborane, etc. is discharged, but if the treatment agent of the present invention is used, phosphine, diborane, arsine, etc. used as such a doping gas can be obtained. The gas has an advantage that it can be removed together with silane, disilane and trisilane gases.

[0012]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Examples 1 to 2 To 2.1 L of Na ₂ CO ₃ solution 3 L, 2 mol of Cu was added.
_{(NO 3) 2 -Al (NO} 3) 3 (Cu 2+ / Al 3+
= 2.3) 3 L of the mixed solution was added dropwise to adjust the pH to 6. During this period, the suspension was rotated at high speed and kept at 40 ° C., and after 30 minutes, washing filtration was performed. This half is dried at 60 ° C. to obtain Al ₃ Cu ₇ (OH) _{2 0} (CO ₃ ) having a specific surface area of 24 m ² / g.
A precursor having an amorphous structure at _1.5 6 H ₂ O was obtained. Resuspend the other half in pure water and spin at high speed for 90
The temperature was kept at 0 ° C. and aging was carried out for 1 hour. Then, it was washed and filtered and dried at 60 ° C. to obtain hydrotalcite having a crystal structure with a specific surface area of 13 m ² / g. The two powders of the same composition were used to measure 3.2 mm x 3.2 on a small tablet machine.
A cylindrical tablet having a diameter of mmφ was formed into a treating agent. Next, the SU with a length of 500 mm and an inner diameter of 25 mmφ shown in FIG.
In the packed column 1 made of S, an apparatus equipped with a gas inlet 2, a gas outlet 3 on both sides, and a thermocouple thermometer 4 in the center of the inside of the column was used. 5 was filled with 100 cc of each, and at room temperature of 25 ° C., 300 c of a gas having a SiH ₄ concentration of 1% diluted with N ₂ was introduced through a gas inlet pipe.
Aeration was performed at c / min. Gas was collected from the gas exhaust port 3 of the packed column 1 and the concentration of monosilane in the gas was analyzed.
The analysis was performed with a gas chromatograph (type 263-30 manufactured by Hitachi) equipped with a photoionization detector. The separation column is Porapak-T, and the detection limit of monosilane is 0.1 ppm. The time until the monosilane was detected from the exhaust port and the maximum temperature during ventilation were measured. Further, after monosilane was detected from the gas exhaust port 3, the inside of the column was purged with N ₂ gas, and Ai was further introduced from the gas inlet port 2.
r was aerated at room temperature of 25 ° C. at a flow rate of 300 cc / min, and the maximum temperature during aeration was measured. As a result, as shown in Table 1, a large amount of heat was not generated. The test results are shown in Table 1.

Examples 3 to 4 2 mol of Mg (NO ₃ ) ₂ -Al (NO ₃ ) was added to ₃ L of 1.8 mol of Na ₂ CO ₃ and 0.4 mol of NaOH solution.
₃ L of ₃ (Cu ²⁺ / Al ³⁺ = 3) mixed solution was added dropwise to adjust the pH to 6. During this period, the suspension was rotated at high speed and kept at 40 ° C., and after 30 minutes, washing filtration was performed. This half was dried at 60 ° C. to obtain a precursor having an amorphous structure with a specific surface area of 27 m ² / g. The other half was aged as in Example 1. Then, it was washed and filtered and dried at 60 ° C. to obtain hydrotalcite having a crystal structure with a specific surface area of 15 m ² / g. Then, cylindrical tablets each having a size of 3.2 mm × 3.2 mmφ were formed by a small tablet machine. This was tested by the same method using the same apparatus as in Examples 1 and 2. The test results are shown in Table 1.

Examples 5 to 6 Al ₂ Mn ₆ (OH) ₁₆ (C having a specific surface area of 16 m ² / g)
O ₃ ) 4H ₂ O hydrotalcite and a precursor having the same composition and an amorphous structure with a specific surface area of 25 m ² / g,
Each is a small tablet machine 3.2 mm x 3.2 m
A cylindrical tablet of mφ was molded. Example 1
A test was conducted in the same manner using the same device as in 2. The test results are shown in Table 1.

Examples 7 to 12 Precursors having the same hydrotalcite and amorphous structure as in Examples 1 to 2 were prepared from three kinds of Al ₂ O ₃ , SiO ₂ and synthetic zeolite (MS-4A). 20 for each carrier
% Loading. This was tested by the same method using the same apparatus as in Examples 1 and 2. The test results are shown in Table 1.

Examples 13 to 15 Al ₃ C molded in Example 1 and having a specific surface area of 13 m ² / g
u ₇ (OH) ₂₀ (CO ₃ ) _1.5 6H ₂ O hydrotalcite was diluted with N ₂ gas shown in Table 1 to 1%, and each silane-based gas was treated in the same manner as in Examples 1 and 2. The test was conducted by the following procedure. The test results are shown in Table 1. The detection limit of the gas is 0.1 ppm in all cases.

[0017]

[Table 1]

Comparative Examples 1 to 12 The silane-containing gas used in the examples was filled in a column with sodium carbonate, manganese oxide, and basic copper carbonate as treating agents and aerated. Others were tested in the same manner as in Examples 1 and 2. The test results are shown in Table 2.

[0019]

[Table 2]

[0020]

EFFECTS OF THE INVENTION In the present invention, it is possible to remove silane-based gas contained in exhaust gas up to 0.1 ppm or less without raising the treatment temperature of the silane-based gas, which has not been achieved by the prior art. This method solves the problems of low heat generation during aeration and heat generation and ignition that occur when the treatment agent after aeration is exposed to the atmosphere. Therefore,
The treatment agent of the present invention can be used extremely safely. That is, Comparative Examples outside the scope of the present invention, the treatment time of the silane-based gas contained in the exhaust gas is short, and when the treatment time is relatively long, when the treating agent after aeration is exposed to the atmosphere. It has the drawback that the heat generated is large and dangerous. On the other hand, the examples within the scope of the present invention are all excellent in these performances. Providing such a silane-based gas treating agent and treatment method can improve the safety and reduce the cost in treating the silane-based gas contained in the exhaust gas in the semiconductor industry. It's done, and the effect is great.

[0021]

[Brief description of drawings]

FIG. 1 is an example of a column sectional view of an exhaust gas treatment method used in the present invention.

[Explanation of symbols]

 1 column 2 gas inlet 3 gas exhaust 4 thermocouple thermometer 5 treatment agent

Claims (3)

[Claims] 1. Among hydrotalcites and precursors having an amorphous structure, represented by the general formula:
^An exhaust gas treating agent containing a silane-based gas in which ³⁺ is a trivalent metal ion, M ²⁺ is a divalent metal ion, and A ⁿ⁻ is an n-valent anion. ^{Embedded image} [M ³⁺ _X M ²⁺ _1-X (OH) ₂ ] ^{X +} [A
_{^{n- X / n mH 2 O]}} X- 2. A method for treating exhaust gas, comprising treating the treating agent according to claim 1 with exhaust gas containing a silane-based gas discharged from a semiconductor device by gas-solid contact. 3. M³⁺Is Al³⁺, Fe³⁺Or C
r³⁺, M²⁺Is Mg²⁺, Mn²⁺Or Cu²⁺Over
And A^n-Is OH⁻, Cl⁻, NO_Three ⁻, CO _Three ^2-Also
Is SO_Four ^2-The treatment agent according to claim 1, which is an anion of