JP3340528B2 - Hazardous gas purification method - 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 purifying harmful gases, and more particularly, to an MOCV in a semiconductor manufacturing process.
The present invention relates to a method for purifying various alkyl hydrogen compound-based harmful gases used in D (metal organic chemical vapor deposition) and other CVD processes.

[0002] In recent years, with the development of the semiconductor industry, high integration and miniaturization have advanced, and instead of hydride-based gases conventionally used, alkyl hydride-based gases such as tert-butylarsine and tert-butylphosphine have been used. The use thereof is increasing, and it is becoming indispensable as a raw material gas, a doping gas, or a gas for forming a metal thin film in a CVD process. These alkyl hydrogen compounds are:
Many are highly toxic or unknown, and
Since most of them are also flammable, their emission after use requires removal of harmful gases and release to the atmosphere.

[0003]

2. Description of the Related Art As a method of removing harmful gases, a wet method of absorbing and decomposing with a scrubber and a dry method of using activated carbon are known. There is no effective absorption solution because the compound is not water-soluble.In the dry method, there is a method using an adsorbent mainly composed of activated carbon or zeolite, but this method not only removes a small amount but also physically adsorbs it. Therefore, there is also a problem that the harmful component once adsorbed is desorbed.

[0004]

Since these alkyl hydride compounds are flammable or ignitable by themselves, especially in combustible adsorbents such as activated carbon, their ability to remove harmful gases is small. Not only that, there is a danger of fire. As described above, the prior art does not have a method for efficiently and safely removing these alkyl hydrogen compounds, and an appearance of an excellent removal method has been desired.

[0005]

Means for Solving the Problems The present inventors diligently study the removal of these periodic table (new experimental chemistry course, 1984 edition, published by Maruzen) from the Vb group element and the alkyl hydrogen compound of the VIb group element. As a result of copper oxide (I
By using a purifying agent obtained by impregnating a cobalt (II) compound component with a metal oxide containing I) and manganese (IV) oxide as a main component, these alkyl hydrogen compounds can be efficiently and safely removed. And found that the present invention was completed. That is, the present invention converts a gas containing at least one of a harmful component, a group Vb element and an alkyl hydrogen compound of a group VIb element, into a metal oxide containing copper (II) oxide and manganese (IV) oxide as a main component. (II) A method for purifying a harmful gas, comprising contacting a compound with a purifying agent to which a compound is impregnated to remove harmful components from the gas.

The purification method of the present invention is contained in a gas such as air, nitrogen and hydrogen, and has a general chemical formula of Rm-M-Hn.
[R is an alkyl group, M is a Vb group or VIb group element, m
And n is a positive integer]. The alkyl hydrogen compound of the Vb group element mainly contains arsenic and phosphorus.
rt- butyl arsine _{(t-C 4 H 9 AsH} 2), te
rt-butyl phosphine (t-C ₄ H ₉ PH ₂ ), isopropyl arsine (i-C ₃ H ₇ AsH ₂ ), isopropyl phosphine (i-C ₃ H ₇ PH ₂ ), etc.
As the alkyl hydrogen compound group Ib element, sulfur, selenium, is intended to include tellurium example, tert- butyl thiol _{(t-C 4 H 9 SH} ), tert- butyl selenol _{(t-C 4 H 9 SeH} ) Tert-butyl tellurol (tC ₄ H ₉ TeH), isopropyl thiol (i-C ₃ H ₇ SH), isopropyl selenol (i-
C ₃ H ₇ SeH), isopropyl terrol (i-C ₃
H ₇ TeH). The purification method of the present invention can remove a large amount of harmful gas quickly and usually at normal temperature. Excellent effects such as rapid purification of air contaminated by gas can be obtained.

In the present invention, a purifying agent in which a cobalt (II) compound is added to a metal oxide is used. Metal oxides include copper (II) oxide and manganese oxide (I
V) as a main component, and may further contain silver oxide, aluminum oxide, silicon oxide, potassium oxide, magnesium oxide, or the like as other oxides. The content of copper (II) oxide and manganese (IV) oxide in the metal oxide is generally at least 60 wt%, preferably at least 70 wt%, in terms of weight ratio. Manganese oxide (I) for copper (II) oxide
The ratio of V) is usually about 1: 0.8 to 5.0, preferably about 1: 1.2 to 3.0. These metal oxide-based compositions can be prepared by mixing various components or by various known methods, but since they are commercially available as hopcalite, it is convenient to use them. Hopcalite is composed of 40% by weight of copper (II) oxide and manganese oxide (I
V) In addition to being commercially available mainly with a 60 wt% two-element system, there are also those in which other oxides as described above are mixed at a ratio of 30 wt% or less, and these may be used as they are, or Further, these oxides may be additionally mixed and used.

The copper (II) oxide and manganese oxide (V
The metal oxide containing I) as a main component is usually used after being molded, and can be used in various shapes such as an extruded product, a tableted product, or a product obtained by crushing them into a suitable size. Its size is 4 to 20 mesh for crushed products, 1.5 to 4 mm in diameter for extruded products, 3 to 20 mm in length, and usually 3 to 6 mm in diameter for tablet molded products, Those having a height of about 3 to 6 mm are preferred.

In the present invention, the cobalt (II) compound to be impregnated on the metal oxide is a cobalt salt of an inorganic acid or an organic acid, and the inorganic acid salt is a salt of an oxo acid or a halide. Examples of oxo acid salts include cobalt salts such as carbonic acid, silicic acid, nitric acid, sulfuric acid, arsenic acid, boric acid, chloric acid, perchloric acid, chlorous acid, and hypochlorous acid. (II), cobalt (II) bromide, cobalt iodide (I
I) and the like. Examples of organic acids include aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, oleic acid, and stearic acid, oxalic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, oxyacids such as lactic acid and tartaric acid, and benzoic acid. Acids, aromatics such as toluic acid, and cobalt (II) salts of various acids such as naphthenic acid may be mentioned. Among these, cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt bromide, cobalt acetate, and the like are preferable in terms of water solubility and ease of handling. Cobalt (II)
Many salts are generally commercially available in the form of hydrates, but any of anhydrous compound salts and hydrated compound salts may be used.

The amount of the cobalt (II) compound impregnated in the metal oxide depends on the type of the alkyl hydride gas,
Although it cannot be specified unconditionally depending on the concentration, it is usually 5 to 50 parts by weight, preferably about 10 to 40 parts by weight, as a compound of each cobalt based on 100 parts by weight of the metal oxide. If the amount is less than 5 parts by weight, the removal efficiency of the alkyl hydrogen compound is low. On the other hand, if it exceeds 50 parts by weight, the metal oxide is not sufficiently retained and the removal efficiency is low and the cost is high. .

In the present invention, the contact temperature between the purifying agent and the gas is generally 100 ° C. or less, and is usually room temperature (10 ° C.).
-50 ° C) and does not require any particular heating or cooling. However, after the start of contact, when the concentration of harmful gas is high or when a highly reducing gas such as hydrogen is contained due to the heat of reaction, the temperature rises by about 10 to 40 ° C due to heat generation. However, there is no danger of abnormal heat generation. The pressure at the time of contact is usually normal pressure, but it is also possible to operate under reduced pressure or a pressurized pressure such as 1 kg / cm ² G. The gas such as air, nitrogen, and hydrogen to which the present invention is applied may be in a dry or wet state as long as it does not cause condensation, but is generally in a range of 30 to 100% corresponding to ordinary atmosphere. It is often used at a relative humidity, and in such a case, a purifying agent having a free water content of about 5 to 15 wt% is suitable.

The concentration and the flow rate of the alkyl hydrogen compound-based gas contained in the gas to be treated to which the purification method of the present invention is applied are not particularly limited, but it is generally desirable that the higher the concentration, the lower the flow rate. The concentration of the harmful gas that can be removed is usually 1% or less, but when the flow rate is small, a higher concentration of an alkyl hydride gas can be treated. The purifying cylinder is designed according to the concentration of the harmful gas, the amount of the gas to be treated, and the like. When the concentration of the harmful gas is relatively low such as 0.1% or less, the linear velocity (LV) of the cylinder is 0.5 to 5
It is preferable to design the LV in the range of 0.05 to 20 cm / sec when the harmful gas concentration is about 0 to 1% at 0 cm / sec and 10 cm / sec or less when the concentration is as high as 1% or more. Therefore, in the case of high concentration harmful gas discharged constantly from the semiconductor manufacturing process, the harmful gas leaks rapidly from the gas cylinder at 10 cm / sec or less and is diluted with a large amount of air. For example, the standard value of LV is 0.5 to 50 cm / sec.

[0013] The purifying agent is usually filled in a purifying column for harmful gas and used as a fixed bed, but can also be used as a moving bed or a fluidized bed. Normally, the purifying agent is filled in the purifying column, and the gas containing the alkyl hydrogen compound-based gas is flowed into the purifying column, whereby the alkyl hydrogen compound, which is a harmful component, is removed by bringing the gas into contact with the purifying agent. In the present invention, the packing density when the purifying agent is filled in the purifying column is about 0.9 to 1.5 g / ml.

[0014]

【Example】

Example 1 to 8 (Mn-Cu composition) manganese dioxide (MnO ₂₎ 50
wt%, copper oxide (CuO) 22 wt%, magnesium oxide (MgO) 12.5 wt%, aluminum oxide (Al
₂ O ₃ ) 12.5 wt%, 1.5 mm in diameter, ₃ to 1 in length
A commercially available hopcalite (manufactured by Nissan Gardler Co., Ltd.), which is a 0 mm extruded product, was used. (Preparation of Purifying Agent) A solution prepared by dissolving 50 g, 200 g, and 500 g of cobalt chloride hexahydrate in water in 1000 g of this hopcalite was sprinkled and impregnated, and dried at 120 ° C. for 2 hours to obtain 100 parts by weight of hopcalite. On the other hand, three kinds of purifying agents impregnated with 5, 20, and 50 parts by weight as cobalt chloride hexahydrate were prepared.

(Purification test)
A 28-mm purification tube was filled with 28 ml, and a purification test of tert-butyl arsine, tert-butyl phosphine, tert-butyl selenol and isopropyl arsine was performed. Each alkyl hydride diluted to a concentration of 0.8 vol% with nitrogen is flowed at a flow rate of 0.85 L / min (linear velocity of the cylinder: 5 cm / sec) at room temperature of 20 ° C. The time until detection started (effective processing time) was measured. For the detection, a detecting agent containing nickel chloride as a color changing component (lower limit of detection: hydrogen arsenide 0.0
5 ppm, hydrogen phosphide 0.3 ppm, hydrogen selenide 0.
05 ppm). Table 1 shows the measurement results.

[0016]

Table 1 Example Noxious gas CoCl ₂ .6H ₂ O Types of effective treatments Amount of application Treatment time (parts by weight) (min) 1 t-BuAsH ₂ 5 922 ₂ ３202963 〃50 2664 t-BuPH ₂ 5 58 5 〃 20 165 6 〃 50 156 7 t-BuSeH 20 185 8 i-prAsH 2 20 230

Examples 9 to 14 (Preparation of Purifying Agents) Three types of purifying agents having different amounts of cobalt sulfate impregnated in the same manner as in Examples 1 to 6, except that cobalt sulfate was used instead of cobalt chloride. Was prepared. (Purification Test) These purifying agents were used in the same manner as in Examples 1 to 6,
Purification tests of tert-butylarsine and tert-butylphosphine were performed. Table 2 shows the results.

[0018]

Table 2 Example CoSO ₄ .7H ₂ O effective treatment of harmful gas Type Immobilization amount Processing time (parts by weight) (min) 9 t-BuAsH ₂ 575 10 {20 259 11} 50 231 12 t-BuPH ₂ 554 13 〃20 152 14 ４50 144

Comparative Examples 1-4 Yashigara activated carbon (manufactured by Takeda Pharmaceutical Co., Ltd.)
8-24 mesh) and Molecular Sieve 5A (8-24 mesh, manufactured by Union Showa Co., Ltd.). (Purification test) 28 ml of these removing agents were filled in a 19 ml inner diameter removal cylinder, heated and regenerated at 200 ° C. while flowing nitrogen, cooled to room temperature, and then tested for tert-butylarsine and tert-butylphosphine. Was done. Table 3 shows the results.

[0020]

Table 3 Comparative Example Harmful Gas Purifier Harmful Gas Cylinder Effective Treatment Type Concentration of Type Linear Velocity Time Vol% cm / sec min 1t-BuAsH2 Activated Carbon 0.85 12 2 {MS5A} 9 3t-BuPH2 activated carbon 〃 〃 84 ＭＳ MS5A 〃 ４ 4

[0021]

According to the method for purifying harmful gas of the present invention,
As harmful gases contained in the gas, tert-butylarsine, tert-butylphosphine and the like, alkyl hydride compound gases of Vb group and VIb group elements, which have been difficult to remove conventionally, particularly harmful gases of relatively high concentration can be efficiently used ,
In addition, since it can be removed very quickly, an excellent effect can be obtained for purifying harmful gases in semiconductor manufacturing equipment and the like.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI B01J 23/889 (56) References JP-A-62-95119 (JP, A) JP-A-60-68034 (JP, A) JP-A-2 -126936 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B01D 53/34

Claims (7)

(57) [Claims] 1. A gas containing at least one alkyl hydride of a Vb group or VIb element, which is a harmful component,
A harmful component characterized by contacting a metal oxide containing copper (II) oxide and manganese (IV) oxide as a main component with a purifying agent obtained by impregnating a cobalt (II) compound with a metal oxide to remove harmful components from the gas. How to purify gas. 2. The method according to claim 1, wherein the Vb group element is arsenic or phosphorus, and the VIb group element is sulfur, selenium or tellurium. 3. An alkyl hydrogen compound wherein the alkyl group is ter
The purification method according to claim 1, wherein the purification method is a t-butyl group or an isopropyl group. 4. The purification method according to claim 1, wherein the cobalt (II) compound is cobalt chloride, bromide, sulfate, nitrate, acetate, or carbonate. 5. The purification method according to claim 1, wherein the amount of the cobalt (II) compound added is 1 to 50 parts by weight based on 100 parts by weight of the metal oxide. 6. The content of copper (II) oxide and manganese (IV) oxide in the metal oxide is 60 wt% or more, and the ratio of manganese (IV) oxide to copper (II) oxide is 1: 1: The purification method according to claim 1, wherein the ratio is 0.8 to 5.0. 7. The purification method according to claim 1, wherein the contact temperature between the purifying agent and the gas is 100 ° C. or lower.