JP2007289883A - Cleaning agent and cleaning method of harmful gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning agent and a cleaning method of harmful gas safely removing silica chlorides from a treating object gas, having no possibility of a rapid exothermic reaction even when the cleaning agent having captured silica chlorides and completed a cleaning reaction should become a high temperature of 300°C or higher, in a dry cleaning method of gas containing silica chlorides as harmful components. <P>SOLUTION: The harmful gas is cleaned using a cleaning agent containing at least one compound selected among basic copper carbonate, aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, and silicon oxide. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a harmful gas purification agent and purification method, and more particularly, a harmful gas containing silicon chlorides such as monochlorosilane, dichlorosilane, trichlorosilane, and silicon tetrachloride as a harmful component is filled with the purification agent. The present invention relates to a purification agent and a purification method that can be introduced into a purification cylinder and can safely remove the harmful components.

Conventionally, in the semiconductor manufacturing industry, dichlorosilane has been used as a raw material for forming insulating films and the like. For example, a method of forming a silicon nitride film (Si ₃ N ₄ ) on a semiconductor substrate such as a silicon wafer by CVD using dichlorosilane and ammonia is performed. In addition, a method of vapor-phase growing tungsten silicide (WSi _x ) by using dichlorosilane and reducing hexafluorotungsten (WF ₆ ) has been implemented.
Silicon tetrachloride is used as a raw material for silica glass useful for liquid crystal panel substrates and the like.

These silicon chlorides are usually discharged after being used in a semiconductor manufacturing process after being diluted with a carrier gas such as nitrogen, hydrogen or helium, but the concentration in the exhaust gas is generally 1% or less. It is. However, since silicon chlorides are highly toxic and adversely affect the human body and the environment, it is necessary to purify harmful gases containing them before use and release them to the atmosphere.
There are wet purification methods and dry purification methods to purify harmful gases containing silicon chlorides, but the wet purification method has a problem that the removal rate of silicon chlorides is low, and the equipment becomes complicated and large, There is a problem that both equipment and maintenance are expensive.

For this reason, as a method of purifying harmful gas containing silicon chlorides, a purifying agent that can react with silicon chlorides and capture this is filled into the purifying cylinder, and the harmful gas is introduced into the purifying cylinder and purified. Many dry purification methods have been implemented to remove harmful components from gases by contacting them with gas. As a purification agent used in the dry purification method, a purification agent containing copper oxide as a main component, a purification agent containing copper hydroxide as a main component (Patent Documents 1 and 2), and a purification containing basic copper carbonate as a main component. An agent (Patent Document 3) has been developed.
JP-A-6-319945 JP-A-7-136451 JP 2002-326017 A

  However, with regard to the purifier containing copper oxide as a main component, when removing silicon chlorides contained in the exhaust gas discharged from the semiconductor manufacturing process or the like, a large amount of hydrogen gas may be contained in the exhaust gas. In many cases, copper oxide is reduced by hydrogen at a temperature of about 110 ° C. or higher. Therefore, when removing a high concentration of the harmful component, the purification agent reaches the temperature by the purification reaction heat, and further, the reaction with hydrogen generates a large amount of heat. There was a possibility of generating.

  In addition, for the purifier containing copper hydroxide as the main component and the purifier containing basic copper carbonate as the main component, the hydrogen reduction temperature is about 150 ° C. or higher, and the safety related to heat generation during the purification is less than that of copper oxide. Although superior to the purifying agent contained as a main component, copper hydroxide has a disadvantage that water is easily generated by the purifying reaction. Furthermore, in any of the above-mentioned purification agents, when the purification reaction-completed purification agent in which silicon chlorides are trapped reaches a high temperature of 300 ° C. or more, there is a possibility that a rapid exothermic reaction occurs.

  Therefore, the problem to be solved by the present invention is when the gas to be treated contains a large amount of hydrogen gas, and the temperature of the purifying agent at the time of purification becomes relatively high (about 110 ° C.). However, silicon chlorides can be safely removed from the gas to be treated, and a sudden exothermic reaction may occur even if the purification agent that has undergone the purification reaction in which the silicon chlorides have been trapped reaches a high temperature of 300 ° C. or higher. It is another object of the present invention to provide a cleaning agent and a cleaning method for harmful gases containing silicon chloride that can be safely purified.

  As a result of intensive studies to solve these problems, the present inventors have as a main component a basic copper carbonate as a gas purification agent containing silicon chlorides, aluminum oxide, aluminum hydroxide, magnesium oxide, water. This is a case where the temperature of the cleaning agent at the time of purification becomes relatively high (about 110 ° C.) by using a cleaning agent containing a small amount of at least one compound selected from magnesium oxide and silicon oxide. However, the harmful components can be safely removed from the gas to be treated, and there is no risk of a sudden exothermic reaction even if the purification agent that has undergone the purification reaction reaches a high temperature of 300 ° C. or higher. As a result, the present inventors have found that it is possible to achieve the purification agent and purification method of the present invention.

That is, the present invention is a harmful containing silicon chloride characterized by containing basic copper carbonate and at least one compound selected from aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, and silicon oxide. It is a gas purifier.
In addition, the present invention includes a gas containing silicon chlorides as a harmful component, including basic copper carbonate and at least one compound selected from aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, and silicon oxide. A method for purifying noxious gas, wherein silicon chloride contained in the gas is removed by contacting with a purifying agent.

  In the purifying agent and the purifying method of the present invention, when removing the silicon chlorides, the purifying agent generates a large exotherm exceeding the hydrogen reduction start temperature, and even if the inside of the purifying cylinder reaches a high temperature of 300 ° C. or higher, Since there is no possibility that the purifying reaction agent that has captured silicon chlorides has undergone a purification reaction and a rapid exothermic reaction occurs, it is possible to safely purify gas containing silicon chlorides as harmful components together with hydrogen.

The purification agent and purification method of the present invention contain one or more types of silicon chloride such as monochlorosilane, dichlorosilane, trichlorosilane, and silicon tetrachloride as harmful components in a gas such as nitrogen, argon, helium, and hydrogen. Applies to purification of harmful gases.
In the present invention, the content of basic copper carbonate used as an active ingredient of the purifier is usually 70 wt% or more, and at least selected from aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, and silicon oxide. The content of one kind of compound is usually 0.1 to 10 wt% in total, preferably 0.1 to 2.5 wt%. When the above components other than basic copper carbonate are less than 0.1 wt%, the safety is lowered, and when it exceeds 10 wt%, the purification ability (the amount of silicon chlorides that can be removed by the unit amount of the purification agent) is lowered. . In addition, purification capacity falls, so that the said components other than basic copper carbonate are contained much.

The purification agent of the present invention can be prepared by various methods, and the production method is not particularly limited. For example, a mixed aqueous solution of copper sulfate and aluminum sulfate is added to an aqueous solution of sodium carbonate, pH is adjusted to produce a precipitate, and the precipitate is washed and dried to thereby obtain basic copper carbonate ((CuCO ₃ ) A purifier containing m · (Cu (OH) ₂ ) n) and aluminum oxide or aluminum hydroxide can be obtained. A purifier containing magnesium oxide, magnesium hydroxide, or silicon oxide can be obtained in the same manner.

The form of the purification agent of the present invention is not particularly limited, but a purification agent having a BET specific surface area of 10 m ² / g or more is preferable, and a purification agent of 30 to ²⁰⁰ m ² / g is more preferable. When a purification agent having a BET specific surface area of less than 10 m ² / g is used, there is a possibility that a high purification ability cannot be obtained. Moreover, even if a purifier having a BET specific surface area of 200 m ² / g or more is used, a high purification capability can be obtained, but there is a restriction that the production is substantially difficult.

  In the purifying agent of the present invention, a binder may be added to the active ingredient in order to increase moldability and molding strength. Examples of such a binder include organic binders such as polyvinyl alcohol, polyethylene glycol, polypropylene glycol, methyl cellulose, and carboxymethyl cellulose, and inorganic binders such as diatomaceous earth, sodium silicate, and sodium hydrogen sulfate. When these binders are added, for example, when preparing a cleaning agent, they are added and kneaded to the powdered or solid active ingredient. The amount of binder added depends on the molding conditions and cannot be specified.However, if the amount is too small, the effect as a binder cannot be obtained. It is 0.1-10 wt% with respect to it, Preferably it is 0.5-5 wt%.

  Further, the purification agent may contain impurities, inert substances, etc. that do not adversely affect the purification of harmful gases containing silicon chloride. Furthermore, the purification agent exhibits excellent purification ability even in a dry state, but may contain 15 wt% or less of moisture. Even when these binders, impurities, inert substances, moisture and the like are included, the content of basic copper carbonate in the purifier is usually 70 wt% or more, preferably 90 wt% or more.

Although the magnitude | size and shape of a purification agent are not specifically limited, For example, spherical shape, a column shape, cylindrical shape, a granular form, etc. are mentioned. The size is preferably 0.5 to 10 mm in diameter if spherical, 0.5 to 10 mm in diameter if cylindrical, such as pellets or tablets, and about 2 to 20 mm in height. The opening of the screen is preferably about 0.84 to 5.66 mm. The filling density when the purification agent is filled in the purification cylinder varies depending on the shape of the purification agent and the preparation method, but is usually about 0.4 to 2.0 g / ml.
The purifying agent is usually filled in a harmful gas purification column and used as a fixed bed, but it can also be used as a moving bed or a fluidized bed. Usually, the purification agent is filled in the purification cylinder, and harmful gas containing silicon chlorides is caused to flow into the purification cylinder, and the silicon chlorides which are harmful components are removed by contacting with the purification agent.

In the purification method of the present invention, the contact temperature between the purification agent and the gas to be treated is 150 ° C. or lower. When purifying silicon chlorides in an inert gas, a gas at a high temperature (150 ° C. or lower) can be directly contacted with a purifier, such as an exhaust gas from a heat treatment process, etc. Since heating and cooling are not required, it is generally 100 ° C. or lower, and is usually operated at a temperature near room temperature (10 to 50 ° C.). Although there is no particular limitation on the pressure during purification, it is usually carried out at normal pressure, but can be operated under reduced pressure such as 10 KPa (absolute pressure) or under increased pressure such as 1 MPa (absolute pressure). is there.
The gas to be treated to which the present invention is applied is a gas such as nitrogen, argon, helium and hydrogen containing silicon chloride as a harmful component, but the gas to be treated is in a dry state or in a high humidity state. However, it is sufficient if it does not cause condensation.

The concentration and flow rate of silicon chlorides 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 to decrease the flow rate as the concentration increases. The concentration of silicon chlorides is usually 1% or less, but higher concentrations of silicon chlorides can be processed when the flow rate is small.
The purification cylinder is designed according to the flow rate of the gas to be treated, the concentration of silicon chloride, etc., but at a relatively low concentration such as a concentration of silicon chloride of 0.1% or less, the empty tube linear velocity (LV) is 0. LV is 0.05 to 20 cm / sec when the concentration of silicon chlorides is about 0.1 to 1%, and 10 cm or less or less at high concentrations such as 1% or more of silicon chlorides. It is preferable to design within the range.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these.

(Preparation of purification agent)
Add a mixed solution of copper sulfate aqueous solution (20 wt%) and aluminum sulfate solution (20 wt%) in which commercially available copper sulfate pentahydrate is dissolved in water to sodium carbonate aqueous solution (20 wt%) in which commercially available sodium carbonate is dissolved in water The pH was adjusted to produce a precipitate. The precipitate was washed and dried to prepare a block-shaped purification agent containing basic copper carbonate (99 wt%) and aluminum oxide (1 wt%).

(Purification test)
The purification agent was filled in a purification cylinder having an inner diameter of 60 mm so as to have a filling length of 100 mm, and a gas containing 5000 ppm of dichlorosilane in dry hydrogen was circulated at a flow rate of 1 L / min at 20 ° C. and normal pressure. During this time, a part of the outlet gas of the purification cylinder is sampled and the time (effective treatment time) until dichlorosilane is detected is measured using a gas detector tube (manufactured by Gastec, detection lower limit 0.05 ppm). Thus, the removal amount (L) (purification ability) of dichlorosilane per 1 L (liter) of the purification agent was determined. The results are shown in Table 1.
(Safety test)
The purified purification agent was brought into contact with a metal rod heated to 300 ° C., 400 ° C., and 500 ° C. in a nitrogen atmosphere, and the presence or absence of reaction was investigated. The results are shown in Table 1.

[Examples 2-3]
Purifying agent containing basic copper carbonate (99.5 wt%) and aluminum oxide (0.5 wt%), purifying agent containing basic copper carbonate (95 wt%) and aluminum oxide (5 wt%) in the same manner as in Example 1. Was prepared.
A purification test and a safety test were conducted in the same manner as in Example 1 except that this purification agent was used. The results are shown in Table 1.

[Comparative Example 1]
In the preparation of the purifying agent of Example 1, a purification test and a safety test were conducted in the same manner as in Example 1 except that the aluminum sulfate solution was not used. The results are shown in Table 1.

As described above, the purifying agent and the purifying method according to the embodiment of the present invention are safe because there is no possibility that a sudden exothermic reaction occurs even if the purifying reaction-finished purifying agent reaches a high temperature of 300 ° C. or higher. Was confirmed.

Claims (5)

  A cleaning agent for harmful gas containing silicon chloride, characterized by comprising basic copper carbonate and at least one compound selected from aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, and silicon oxide.   The content of basic copper carbonate is 70 wt% or more, and the content of at least one compound selected from aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, and silicon oxide is 0.1 to 10 wt%. The harmful gas purifier according to claim 1.   2. The harmful gas purifier according to claim 1, wherein the silicon chloride is at least one compound selected from monochlorosilane, dichlorosilane, trichlorosilane, and silicon tetrachloride.   A gas containing silicon chloride as a harmful component is brought into contact with basic copper carbonate and a cleaning agent containing at least one compound selected from aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, and silicon oxide. A method for purifying noxious gas, wherein silicon chloride contained in the gas is removed. The method for purifying harmful gas according to claim 4, wherein the silicon chloride is at least one compound selected from monochlorosilane, dichlorosilane, trichlorosilane, and silicon tetrachloride.