JPH1119475A - Method of purifying harmful gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable purifying a large flow rate of gaseous hydridecontaining harmful gas with high purifying capacity even in the presence of moisture by bringing harmful gas containing gaseous hydride as harmful components into contact with a purifying agent consisting essentially of copper oxide and silver oxide. SOLUTION: A purifying pipe 1 is packed with a purifying agent 2 consisting essentially of copper (II) oxide and silver (I) oxide. Between a cylinder cabinet 4 for housing a gas cylinder 3 and a blower 5 for continuously sucking air in the cylinder cabinet 4 to ventilate it, the purifying pipe 1 is installed through a ventilating duct 6. And when gas which is gaseous hydride such as arsine, phosphine, silane, disilane and trisilane in the gas cylinder 3 leaks from the gas cylinder 3, the blower 5 installed at the poststage of the purifying pipe 1 is switched to large flow rate operation, and harmful gas is led together with a large quantity of air taken in from an air intake 7 to the ventilating duct 6 to purify it in the purifying pipe 1, allowing it to be discharged as gas madeharmless.

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 gas, and more particularly, to a method for purifying harmful gas efficiently when a large amount of hydride gas is suddenly leaked into the atmosphere from a cylinder or the like. A gas purification method.

[0002]

2. Description of the Related Art In recent years, with the development of the semiconductor industry and the liquid crystal industry, the types and amounts of hydride gases such as arsine, phosphine, silane and diborane used in these processes have been increasing.

[0003] These hydride gases are indispensable as a source gas or a doping gas in the production process of silicon semiconductors, compound semiconductors, liquid crystals and the like.
All are extremely toxic, and their allowable concentrations are 0.05 ppm for arsine (AsH ₃ ) and phosphine (PH).
₃ ) 0.3 ppm, silane (SiH ₄ ) 5 ppm,
It is 0.05 ppm in diborane (B ₂ H ₃ ).

[0004] For this reason, if a harmful gas containing a high concentration of hydride gas is discharged into the atmosphere, there is a danger of not only destroying the environment but also killing human life. It is necessary to purify until the concentration of the hydride gas in the harmful gas becomes lower than the allowable concentration.

In a semiconductor or liquid crystal manufacturing plant, these hydride gas cylinders are usually placed in a cylinder storage container called a cylinder cabinet in order to prevent the outside air from being directly polluted when the gas leaks. In the stored state, it is used by being connected to a gas supply pipe to a manufacturing process or the like. Thus, even if the cylinder is stored in the cylinder cabinet, there is no danger of gas leaking due to an unexpected accident, and when such an accident occurs, it must be quickly cleaned. Also, in the manufacturing process, there is a risk that gas leaks from a manufacturing apparatus or a gas supply pipe and contaminates the environment of the manufacturing site. In such a case, the harmful gas must be urgently purified.

As a method for purifying harmful gases containing these hydride gases as harmful components, a wet purification method and a dry purification method are known. Examples of the wet purification method include a method in which a hydride-based waste gas is brought into contact with an alkaline solution and irradiated with ultraviolet rays to remove the harmful substances (Japanese Patent Laid-Open No. 3-178317).
There is known a method in which a hydride-based waste gas is brought into contact with an alkali solution and subjected to ultrasonic waves to remove harm (Japanese Patent Application Laid-Open No. 3-178318). Examples of the dry purification method include a method of removing a honeycomb formed body made of a metal compound selected from copper, zinc, iron, silicon, phosphorus, manganese, and aluminum by contact with a harmful gas (Japanese Patent Application Laid-Open No. 64-15135); Of removing a silane-based gas containing diborane or arsine by passing through a packed layer containing a solid metal oxide as a main component (JP-A-5-269347), using cupric oxide, AgO, HgO, CdO Of 1
There is known a method of contacting a gaseous hydride with a catalyst containing at least one of them to remove the gaseous hydride (JP-A-5-317715).

[0007]

In purifying harmful gas when harmful components such as arsine and phosphine leak into the atmosphere from cylinders, pipes or equipment using these gases, a large flow of harmful gas is used. It needs to be processed quickly and requires high purification capacity. In order to purify hydride gas leaked into the atmosphere in the presence of air,
Often contains water. Further, at a manufacturing site, it is desired to purify harmful gases in the vicinity of the manufacturing apparatus from the viewpoint of safety, and downsizing of the purification apparatus is required to reduce the cost of the purification apparatus.

[0008] However, the above-mentioned wet purification method requires an ultrasonic generator or an ultraviolet ray generator, so that the equipment becomes large, the use of an alkaline solution causes corrosion of the purification device by a chemical solution, and low purification ability. There are problems. In addition, the methods (1) and (2) have a problem that the purifying ability is easily lowered by moisture in the air, and the harmful gas cannot be sufficiently purified in the presence of moisture.
On the other hand, the method (1) has insufficient purification ability, and
When O is used, AgO is chemically unstable.
Furthermore, AgO has a problem that it is expensive.

In view of the above, it is strongly desired to develop a method for purifying harmful gases containing hydride gas, which is compact in size, has a high purifying ability, and does not decrease its capacity even in the presence of moisture. Was rare.

[0010]

The present inventors have made intensive studies to solve these problems and found that arsine,
When purifying harmful gases when hydride gas such as phosphine leaks into the atmosphere from cylinders, pipes, or equipment that uses these gases, purifying mainly copper (II) oxide and silver (I) oxide It has been found that the use of an agent can provide a large purification capacity which has not been expected in the past, and completed the present invention.

That is, the present invention provides a method for purifying a harmful gas containing a hydride gas as a harmful component by contacting the harmful gas with a purifying agent containing copper (II) oxide and silver (I) oxide as main components. This is a method for purifying harmful gases.

The purifying agent used in the present invention is copper (II) oxide.
And silver (I) oxide as main components, whereby hydride gas such as arsine, phosphine, silane, disilane, trisilane, diborane, hydrogen selenide and the like contained in the air or the like can be obtained by a conventionally known method. It can be purified with high purification ability that has not been obtained and without being affected by moisture.

Silver (I) oxide in the purifying agent used in the present invention
When the amount is too small, a sufficient purifying ability cannot be obtained, and when the amount is too large, the purifying agent becomes expensive. Therefore, the amount is usually 0.1 to 20% by weight based on the total weight of the purifying agent. Preferably it is 1 to 15% by weight.

The purifying agent used in the present invention is copper oxide.
It may be a mixed molded product of (II) and silver oxide (I), or may be a molded product of copper oxide (II) with silver oxide (I) impregnated thereon.

As a method for preparing the purifying agent, various known methods are used. As a method of preparing a mixed molded body of copper oxide (II) and silver oxide (I), for example, water is added to a mixture obtained by preliminarily mixing copper oxide (II) and silver oxide (I) at a predetermined ratio. Extruding the slurry or cake obtained by stirring, drying the pellets obtained by cutting to an appropriate length to obtain a purifying agent, or crushing after drying the slurry or cake as described above, Examples include a method of tableting and forming a purifying agent, and a method of forming a slurry or cake into granules using a granulator or the like to obtain a purifying agent. Among these, a method of forming a pellet by extrusion molding is preferable from the viewpoint of workability, ease of selection of shape and size, and the like.

When preparing a molded article, a binder may be added to enhance moldability and molding strength. Examples of the binder include polyvinyl alcohol, polyethylene glycol, polypropylene glycol, methyl cellulose, carboxymethyl cellulose, silica, diatomaceous earth, sodium hydroxide, potassium hydroxide, and sodium silicate. These are added and kneaded to the powder raw material when preparing the purifying agent. The amount of the binder to be added is different depending on the ratio of each component, molding conditions and the like, and cannot be specified unconditionally.However, if the amount is too small, the effect as the binder is not obtained, and if the amount is too large, the purification ability is reduced. It is 0.1 to 15% by weight, preferably 0.5 to 7% by weight, based on the total weight of the purifying agent.

When a purifying agent is prepared by impregnating copper (II) with silver oxide (I), the preparation of the copper oxide (II) molded product is performed by mixing the above copper (II) oxide and silver (I) oxide. It can be carried out by a method similar to the method of preparing a molded body. Copper (II) oxide to silver (I) oxide
As a method for attaching, a wet method or a dry method may be used. As a wet method, there is a method in which silver (I) is applied as an aqueous slurry. In addition, as a dry method, there is a method of dusting silver (I) oxide on a copper (II) oxide molded body.

The size and shape of the purifying agent used in the present invention are not particularly limited, and examples thereof include a sphere, a column, a cylinder and a particle. Its size is 0.5 to 10 mm in diameter if it is spherical, 0.5 to 10 mm in diameter if it is columnar such as pellets or tablets, and 2 to 20 in height.
mm is preferable, and if it is irregular, such as granular,
A sieve with an opening of about 0.84 to 5.66 mm is preferred. The packing density when the purifying agent is filled in the purifying column varies depending on the shape of the purifying agent, but is usually 0.5 to 2.0 g.
/ Ml.

The purifying agent used in the present invention can be used not only as a fixed bed but also as a moving bed or a fluidized bed, but is usually used as a fixed bed. The purifying agent is charged into the purifying cylinder, and the harmful gas guided into the purifying cylinder is purified by contact with the purifying agent.

The filling length of the purifying agent in the case of a fixed bed varies depending on the flow rate of gas and the concentration of harmful components in harmful gas, and cannot be specified unconditionally.
It is about 00 mm. The inner diameter of the purifying cylinder has a size such that the linear velocity (LV) of the gas flowing in the cylinder becomes about 0.3 to 1.5 m / sec. Generally, these are determined by the pressure loss of the packed bed, the contact efficiency with the gas, the concentration of harmful components in the harmful gas, and the like.

The concentration of the harmful components in the harmful gas that can be purified by the present invention is not particularly limited. However, when the concentration of the harmful component is high, the temperature rises due to the reaction heat generated by the reaction between the purifying agent and the harmful component, which may be dangerous.
For this reason, it is preferable to dilute the concentration to a low concentration of 1% or less by mixing with air. Usually, a suction blower is provided. The blower has a ventilation capacity of 5-200m
Those having a rate of about ³ / min are often used. When such a blower is used, the concentration of the harmful components in the harmful gas introduced into the purification column is 50 to 1000 p, even if a large amount of leakage occurs such that a commercially available gas cylinder becomes empty in 5 to 10 minutes.
pm. The blower is also provided for the purpose of forcibly guiding the harmful gas to the purification column when harmful components leak.

As described above, the present invention purifies harmful gases containing harmful components in the presence of a large amount of air, so that the same conditions as ordinary atmospheric environments, that is, a relative humidity of 30 to 1 are used.
Although it is often used under an environment of 00%, according to the present invention, even when such moisture is contained, it can be sufficiently purified. It is not affected by carbon dioxide in the air.

The hydride gas is filled in a cylinder in a state diluted with a gas such as nitrogen or argon, and diluted with a gas such as nitrogen or argon when supplied to a semiconductor or liquid crystal manufacturing apparatus. Supplied as is. Therefore, such a gas is present even at the time of leakage, but according to the present invention, the purification ability does not decrease even in the presence of such a gas.

The temperature at which the harmful gas is brought into contact with the purifying agent is usually 0 to 90 ° C., preferably a temperature around room temperature (10 to 40 ° C.).
° C) and does not require special heating or cooling. Of course, after the start of contact, due to the heat of reaction, the temperature rises according to the concentration of the harmful component, but the purification ability does not decrease. The pressure at the time of contact is usually normal pressure, but it can be operated under reduced or increased pressure. In addition, the contact time is usually 0.1.
01 second or more, preferably 0.025 second or more. If the contact time is shorter than 0.01 second, a sufficient purification ability may not be obtained.

[0025]

FIG. 1 shows an embodiment of the purification method of the present invention. A purifying cylinder 1 is filled with a purifying agent 2 and is provided through a ventilation duct 6 between a cylinder cabinet 4 accommodating a gas cylinder 3 and a blower 5 for continuously sucking and ventilating the air in the cylinder cabinet 4. A purifying cylinder 1 is installed. If gas in the cylinder leaks from the gas cylinder 3 in the cylinder cabinet 4,
The blower 5 installed at the subsequent stage is switched to the large flow operation, and the harmful gas is guided to the ventilation duct 6 together with a large amount of air taken in from the air intake port 7, purified by the purification column 1, and detoxified gas Is discharged.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 84% by weight of copper (II) oxide, 15% by weight of silver (I) oxide, 1
Purification agent A consisting of a binder in an amount of 1% by weight is filled in a quartz purification cylinder having an inner diameter of 19 mm so as to have a filling length of 100 mm, and air containing 500 ppm of phosphine at 60% relative humidity and a temperature of 25 ° C. It was circulated at a rate of 7 l / min (linear line velocity LV = 75 cm / sec). A part of the outlet gas of the purification column is continuously sampled by a semiconductor material gas leak detection alarm (manufactured by Nippon Sanso Corporation: HD-1), and the time until the concentration of phosphine in the outlet gas rises to 28 ppb ( Effective processing time) was measured. Table 1 shows the results.

Example 2 Example 1 was carried out using a purifying agent B consisting of 93% by weight of copper (II) oxide, 6% by weight of silver (I) oxide and 1% by weight of a binder.
A purification ability test was performed under the same conditions as described above. Table 1 shows the results.

Example 3 Example 1 using a purifying agent C comprising 98% by weight of copper (II) oxide, 1% by weight of silver (I) oxide and 1% by weight of a binder.
A purification ability test was performed under the same conditions as described above. Table 1 shows the results.

Example 4 The same type of purifying agent A as used in Example 1 was used with an inner diameter of 19 mm.
Is filled so that the filling length is 100 mm, and air containing 500 ppm of arsine is 12.7.
1 / min (linear linear velocity LV = 75 cm / sec). A part of the outlet gas of the purifying column is continuously sampled by a semiconductor material gas leak detection alarm (manufactured by Nippon Sanso Corporation: HD-1), and the concentration of arsine in the outlet gas is 22.
The time required to increase to ppb (effective treatment time) was measured. Table 1 shows the results.

Comparative Example 1 A purifying ability test was carried out under the same conditions as in Example 1 using Purifying Agent D comprising 99% by weight of copper (II) oxide and 1% by weight of a binder. Table 1 shows the results.

Comparative Example 2 84% by weight of copper (II) oxide, 15% by weight of silver (II) oxide, 1
A purifying ability test was carried out under the same conditions as in Example 1 using the purifying agent E consisting of a binder by weight. Table 1 shows the results.

Comparative Example 3 84% by weight of copper (I) oxide, 15% by weight of silver (II) oxide, 1
A purifying ability test was carried out under the same conditions as in Example 1 using the purifying agent F composed of a binder by weight. Table 1 shows the results.

[0034]

TABLE 1 harmful components cleaning agent effective treatment time (min) Example 1 phosphine CuO + Ag ₂ O 341 Example 2 Phosphine CuO + Ag ₂ O 339 Example 3 phosphine CuO + Ag ₂ O 337 Example 4 arsine CuO + Ag ₂ O 375 Comparative Example 1 Phosphine CuO Instantaneous Breakthrough Comparative Example 2 Phosphine CuO + AgO 222 Comparative Example 3 Phosphine Cu ₂ O + AgO 227

[0035]

According to the present invention, even when a large flow of harmful gas containing hydride gas such as arsine, phosphine, silane, disilane, trisilane, diborane and hydrogen selenide as harmful components is used even in the presence of moisture. It can be purified with a very high purification capacity. For this reason, an excellent effect can be obtained in purifying harmful gases when these gases leak from a cylinder, a semiconductor manufacturing apparatus, a gas supply pipe, or the like. In addition, since it has a large purification ability even at a temperature near room temperature, facilities such as heating and cooling are not required, and the purification device can be downsized. Furthermore, since the chemically stable silver oxide (I) is used as the purifying agent component, the purifying agent does not deteriorate, and compared with the case where silver (II) oxide is used.
Purifiers are inexpensive.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a device for purifying gas leaked from a cylinder cabinet, which is an embodiment of the purification method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Purifier 2 Purifier 3 Gas cylinder 4 Cylinder cabinet 5 Blower 6 Ventilation duct 7 Air intake

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Nagao Furuura 5181 Tamura, Hiratsuka-shi, Kanagawa Prefecture Japan Hiratsuka Research Laboratories

Claims (3)

[Claims] A harmful gas containing a hydride gas as a harmful component is brought into contact with a purifying agent containing copper (II) oxide and silver (I) oxide as main components to purify the harmful gas. How to purify harmful gases. 2. The method of claim 1, wherein the hydride gas is arsine, phosphine,
The purification method according to claim 1, wherein the method is at least one selected from silane, disilane, trisilane, diborane, and hydrogen selenide. 3. The method according to claim 1, wherein the content of silver (I) in the cleaning agent is 0.1% by weight to 20% by weight based on the total weight of the cleaning agent.