JPH0783820B2 - Advanced treatment method for exhaust gas - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for advanced treatment of silane-based exhaust gas. More specifically, the present invention relates to a method for treating advanced exhaust gas in which exhaust gas of a silane-based gas containing a dopant such as phosphine, diborane or arsine for semiconductor production is passed through a packed layer containing a solid metal oxide as a main component and contact-treated.

[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. Such semiconductor manufacturing gas, especially silane-based gas such as monosilane (SiH ₄ ), disilane (Si ₂ H ₆ ), trisilane (Si ₃ H ₈ ), is a single crystal by a method such as thermal decomposition, photodecomposition, and plasma decomposition. It is an essential gas for forming silicon, polycrystalline silicon, amorphous silicon, silicon oxide film, silica nitride film, etc. 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, There are immeasurable negative effects on the natural environment. Therefore, in Japan, the regulation of the concentration of silane-based gas in exhaust gas in the semiconductor industry is being strengthened for the purpose of maintaining a good working environment and preventing the destruction of the natural environment. Moreover, in the United States, the US Conference of Industrial Hygienists sets a working environment concentration of monosilane of 0.5 pp.
Strict regulations such as setting m will be enforced. Normally, for semiconductor manufacturing, a gas such as hydrogen, helium, argon, or nitrogen is used, and a silane-based gas is used from several% to several tens%.
Although a diluted gas is often used, sometimes a 100% undiluted silane-based gas is used.

Semiconductor manufacturing apparatuses are roughly classified into a normal pressure method and a reduced pressure method depending on the film growth method. In case of normal pressure method,
A large amount of gas containing a high concentration of silane-based gas is discharged, but usually, it is treated by a device devised so that the exhaust gas is mixed with air and burned, or brought into contact with an aqueous alkali hydroxide solution (Japanese Patent Laid-Open No. Sho 61-96 56-84619, 57-9
No. 4323) and the like to reduce the silane-based gas concentration as much as possible, and then release it to the atmosphere.

On the other hand, the depressurization method has an advantage that it can be mass-produced and a thin uniform film can be obtained, but since the vacuum pump is interposed between the reaction chamber (film forming chamber) and the exhaust gas treatment device, the vacuum pump is used. Unreacted silane gas may be mixed in to cause troubles such as pump failure, deterioration, and ignition. Therefore, a method has been adopted in which a metal filter such as aluminum heated at high temperature is attached between the reaction chamber and the vacuum pump to treat silane gas (Japanese Patent Laid-Open No. 53-99071).
issue). However, in the exhaust gas treated by these conventional methods such as combustion, contact treatment with an aqueous alkali hydroxide solution, or treatment with a metal filter, a high-concentration silane-based gas of 5 ppm or more remains, This number cannot be overlooked from the viewpoint of protection of the natural environment and occupational health and safety. As well,
The method using a metal filter has a constraint that it must be heated to 600 ° C. or higher. Therefore, development of a method that can be used not only in the room temperature method but also in the depressurization method and that completely removes the silane-based gas in the exhaust gas to at least 0.5 ppm, preferably about 0.1 ppm is expected. That's why.

[0005]

That is, an object of the present invention is to provide a means for almost completely removing the silane-based gas in the exhaust gas of a semiconductor manufacturing apparatus, and the gist of the invention is to provide such a semiconductor. The exhaust gas containing the silane-based gas from the manufacturing method device has a concentration of the silane-based gas in the exhaust gas of at least 0.5 ppm or less, preferably 0.1 ppm or less, that is, the content is substantially zero, and the silane-based gas is Another object of the present invention is to provide a means for removing phosphine, diborane, or arsine, which is a dopant contained in the exhaust gas, together with the silane-based gas.

[0006]

Means for Solving the Problems The above-mentioned problem is that a silane-based exhaust gas which is discharged from a semiconductor device and contains phosphine, diborane and / or arsine together with a silane-based gas is filled with a filling layer containing a solid metal oxide as a main component. A silane containing phosphine, diborane and / or arsine, which is passed through to efficiently remove the concentration of the silane-based gas to at least 0.5 ppm or less and remove phosphine, diborane and / or arsine together with the silane-based gas. Advanced exhaust gas treatment method, more preferably, the solid metal oxide is Li, N
a, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Al, Ga, In, T
l, Si, Ge, Sn, Pb, Sb, Bi, Cu, Ag, Au, Zn, Cd, H
g, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, M
o, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Pt, La, Ce, P
r, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
The advanced treatment method is an oxide of at least one metal selected from the group consisting of u, Th and U.

The present invention will be described in detail below. Examples of the solid metal oxide used in the packed bed of the present invention include hydrogen of the group Ia, elements other than francium, ie; Li,
Na, K, Rb, Cs IIa elements other than Ra, ie; Be, Mg, Ca, Sr, Ba IIIa elements other than boron, ie; Al, Ga, In, Tl IVa elements other than carbon, ie; Si, Ge, Sn, Pb Elements of the Va group except nitrogen, phosphorus and arsenic; ie, Sb, Bi Ib groups; Cu, Ag, Au IIb groups; Zn, Cd, Hg lanthanum- and actium-based thorium and uranium Metal elements of transition elements including, namely, Sc, Ti, V, Cr, Mn,
Fe, Co, Ni, Y, Zr, Nb, Mo, Ru, Rh, Pd, Hf, Ta,
W, Re, Os, Pt, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, T
Examples thereof include particles of oxides such as b, Dy, Ho, Er, Tm, Yb, Lu, Th, U; and the like, and these are used alone, as a mixture, or as supporting a metal.
In addition, the periodic table referred to here means the one described in "Chemical Dictionary" (edited by the Chemical Dictionary Editorial Committee, published by Kyoritsu Shuppan, Vol. 10).

According to the present invention, a phosphine, together with a silane-based gas, is added to a filling layer containing the above-mentioned metal oxide particles as a main component.
Aeration treatment is preferably performed on a silane-based exhaust gas containing diborane or arsine. In this case, it is desirable that the metal oxide particles as the treating agent be made fine and have a surface area of 0.1 m ² / g or more to improve the gas-solid contact ability with the silane-based gas. The metal oxide particles are not particularly limited, and those which are available as ordinary reagents or industrial chemicals are preferably used. 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. Alternatively, the metal compound may be precipitated from a solution of a soluble metal compound corresponding to the target metal oxide by a conventional method, and then separated and fired to obtain the metal oxide.

Further, in order to enhance the exhaust gas treating ability of the metal oxide as a 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 types of metal oxides 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. As shown in the examples, in the treatment with the metal oxide in the present invention, the temperature of the packed bed is 200 ° C. or less, and the concentration of the silane-based gas in the exhaust gas is 0.1 ppm or less, that is, the detection limit or less. You can

As the packing layer for carrying out the present invention,
Although an I-series packed bed is also sufficient, it is preferable to use a plurality of parallel packing systems from the viewpoint of operation such as regeneration and replacement of packings, and use each of them as a treatment layer and a re-treatment layer, which are mutually switched and used. As described above, in the actual semiconductor manufacturing, since the silicon film is often doped with silane gas such as arsenic, boron, phosphorus, etc. However, if the treating agent of the present invention is used, the silane-based gas concentration is efficiently removed to at least 0.5 ppm or less, and
Gases such as phosphine, diborane, and arsine used as the doping gas can be removed together with the silane-based gas. Less than,
The present invention will be specifically described with reference to examples.

[0011]

【Example】

Examples 1 to 53 FIG. 1 shows the experimental apparatus used in the examples. 1 is 25 mmφ
× 450 mmL quartz tube, 150 ml of the treating agent comprising the solid metal oxide particles of the present invention, and packed bed height 300 m
It was filled so as to be m to obtain a filled layer 2. The portion of the packed bed can be heated in the electric furnace 3 in the range of room temperature to 800 ° C. Dilute pure monosilane gas with nitrogen gas,
A monosilane-containing gas having a predetermined concentration was adjusted and stored in the gas reservoir 4. Next, this gas was aerated through the mass flow controller 5, the valve 6 and the pump 7 to the packed layer 2 containing a treatment agent composed of a solid metal oxide (sieved and having a uniform particle size) as a main component. The treated gas obtained from the packed bed outlet 8 was introduced into a gas chromatograph through a gas chromatograph sampler, and the monosilane concentration in the gas was analyzed. The analysis was performed by a gas chromatograph equipped with a photoionization detector. The separation column is Porapak-T, and the detection limit of monosilane is 0.1 ppm. The experimental results are shown in Table 1. In FIG. 1, 8 is a supply port of N ₂ gas for purging and 9 is also an outlet.

Examples 54 to 106 Pure disilane gas was diluted with nitrogen gas to prepare a disilane-containing gas having a predetermined concentration. Then, an experiment was conducted in the same manner using the same apparatus as in Examples 1 to 53. The detection limit of disilane gas chromatograph analysis is 0.1 ppm. The experimental results are shown in Table 2.

Examples 107 to 116 Monosilane or disilane was diluted to a predetermined concentration with nitrogen gas, and this was further mixed with an equivalent amount of air and partially combusted, and the gas was treated in the same manner as in Examples 1 to 53 to obtain monosilane. Alternatively, disilane was analyzed. The experimental results are shown in Table 3.

Comparative Examples 1 to 12 Experiments were carried out in the same manner as in Examples 1 to 50 with the gas containing monosilane or disilane used in Examples being passed through the filled layer of glass, natural quartz and silver sand. The experimental results are shown in Table 4.

Examples 117 to 128 Experiments were conducted in the same manner as in Examples 1 to 53. However, subject
SiH as a natural gas_Four-AsH _3-N₂System, SiH_Four-PH₃-N₂System or Si
H_Four-B₂H_6-N₂CuO alone, CuO-
ZnO (Cu / Zn atomic ratio = 1), Cu₂O-ZnO (Cu / Zn atomic ratio = 1
 ) Or Cu₂O alone was used. The analysis is SiH_Four, AsH₃Oh
And PH₃For the same as in Example 1, B₂H₆Is gas
Since black analysis could not be done, the drainage made by West Germany Dräger
-Sampling was performed with a gel detector tube and gas analysis was performed. result
Is shown in Table 5. According to the removal method of the present invention, a silane-based gas is used.
Dopants such as phosphine, arsine and divo
If it contains orchid, together with the silane-based gas,
Having the advantage that these can also be removed
I understand.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

[0021]

[Table 6]

[0022]

[Table 7]

[Brief description of drawings]

FIG. 1 is a flow sheet diagram showing an apparatus for carrying out the present invention.

[Explanation of symbols]

 1 quartz tube 2 packed bed 3 electric furnace 4 gas reservoir 5 mass flow controller 6 valve 7 pump 8 packed bed outlet

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Claims (2)

[Claims] 1. A silane-based exhaust gas discharged from a semiconductor device and containing phosphine, diborane and / or arsine together with a silane-based gas is passed through a packed layer containing a solid metal oxide as a main component to obtain a concentration of the silane-based gas. Is efficiently removed to at least 0.5 ppm or less, and phosphine, diborane and / or arsine,
A method for advanced treatment of silane-based exhaust gas containing phosphine, diborane and / or arsine, which is removed together with the silane-based gas. 2. The solid metal oxide is Li, Na, K, Rb, C.
s, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, S
n, Pb, Sb, Bi, Cu, Ag, Au, Zn, Cd, Hg, Sc, Ti,
V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Ru, Rh, P
d, Hf, Ta, W, Re, Os, Pt, La, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th and U
The treating agent according to claim 1, which is an oxide of at least one kind of metal selected from the group consisting of: