JPS58128146A - Absorbing agent - Google Patents

Abstract

PURPOSE:To provide an absorbing agent for harmful gases such as volatile inorg. hydrides or volatile inorg. halides by impregnating an aq. alkali soln. in a solid carrier consisting essentially of porous inorg. silicate. CONSTITUTION:An aq. alkali soln. of 5-50% concn of NaOH, KOH, Ca(OH)2, etc. is impregnated into a carrier 1 consisting essentially of porous inorg. silicate such as diatomaceous earth, calcium silicate, bentonite or the like in 0.2-2 proportion. Or further, an oxidizing agent such as KMnO4 is further impregnated thereto. Gases contg. toxic volatile inorg. hydrides such as silane, diborane, hydrogen selenide, etc. or toxic volatile inorg. halides such as dichlorosilane, trichlorosilane, etc. are passed through said agent, whereby these toxic gaseous components are removed by absorption.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a volatile inorganic hydride such as silane, dipora/hydrogen selenide, and a volatile inorganic halide O1k collection agent such as dichlorosilane and trichlorosilane.

For example, in the production of IO and 18I in the semiconductor industry, volatile inorganic hydrides and volatile inorganic halides are used in gaseous or liquid form for mineral phase growth, etching, dobindering, or diffusion. ing. By the way, all of these are highly toxic; for example, even if a small amount of silica leaks into the air, it reacts violently with oxygen in the air and burns6], and diborane, hydrogen selenide, and germane are highly toxic. It is well known to be toxic.

Therefore, great care must be taken when handling them; for example, in the semiconductor manufacturing process mentioned above, waste gas containing these hazardous components must be safely disposed of. For this reason, various methods have been proposed to remove these harmful components, but in general, the waste gas containing harmful components is absorbed into a caustic soda (Na(JH)) aqueous solution. Normally, the treatment is carried out by a wet absorption method in which harmful components are absorbed and removed by an aqueous solution of caustic soda by bringing them into countercurrent contact with aqueous sodium hydroxide solution.

This method has the advantage that it can be treated with inexpensive caustic soda, but it has the disadvantages that depending on the type of gas, the equipment becomes large in order to obtain a sufficient absorption and removal effect9, and a large amount of aqueous caustic soda solution is required.

Furthermore, since the waste liquid after absorbing harmful components is an alkaline aqueous solution, it is inconvenient to handle, and there are also drawbacks such as difficulty in disposing of the waste salt, increasing transportation costs, and increasing the amount of treatment. The more you do this, the more the above-mentioned drawbacks become more serious.

In view of the above circumstances, the inventors of the present invention have conducted various studies aimed at efficiently removing harmful components in waste gas mainly from semiconductor manufacturing, and have found that the main component is porous inorganic silicate. We discovered that by using a solid treatment agent made by impregnating a lj1m carrier with an aqueous alkaline solution, absorption efficiency not found in the conventional methods described above could be obtained. That is, the present invention is based on this knowledge and uses IR-emitting inorganic hydrides such as silane, dibotun, hydrogen selenide, and germane, as well as dichlorosilane and trichloride.
The first invention relates to a solid treatment agent using a dry absorption method that can safely and efficiently treat waste gas containing one or more volatile inorganic halides such as Lucilan, and the first invention is a solid treatment agent that is mainly composed of a porous inorganic silicate. The second invention is a gas treatment agent characterized by impregnating a solid filter carrier with an aqueous alkali solution, and further impregnating an oxidizing agent such as potassium permanganate thereon.

The present invention will be explained in detail below.

As a solid carrier which is one of the components of the present invention, diatomaceous earth, calcium silicate, bentonite, Kanuma earth, etc. can be used, but as a result of various experiments, diatomaceous earth was found to be optimal.

Next, as the alkaline aqueous solution, caustic soda (NaOH),
Caustic potash (KUH), calcium hydroxide (Oa (J
Although there are H)m), etc., caustic soda is preferable from an economic point of view.

In view of the above points, the case where silane is removed by selecting diatomaceous earth as the solid carrier and selecting a caustic soda solution as the alkaline aqueous solution will be described below.

If the concentration of the caustic soda solution is too low, it will not react with the silane,
Also, if the temperature is too high, diatomaceous earth will be dissolved and it will be difficult to handle the solution in good condition for practical use, so it should be set at 5 to 50% (by weight).

Next, as a result of an experiment on the reactivity with silane with respect to the mixing weight ratio of diatomaceous earth and caustic soda solution, it was confirmed that it is good to increase the caustic soda solution to 0.2 to 2 times (weight ratio) to diatomaceous earth ±IK. The hard scale treatment agent produced in this manner has the ability to absorb hydrogen selenide.

Example 1 will be explained below.

[Example 1] 150 g of 104 caustic soda aqueous solution to ±100 g of diatomaceous
When 100 g of the silane impregnated with silane was filled into cylinders with an inner diameter of 2 cm and a height of 5 degrees, and the silane concentration at a concentration of 10.5% was measured, it was less than sppm. Nine, the outlet concentration is soo
The amount of silane absorbed by the treatment agent 1-1 of the present invention is calculated as the breakthrough point of the treatment agent at 9 o'clock when the amount of silane absorbed is approximately 26 ML/
Six nine in 11f.

Comparing the above examples with the conventional hot absorption method described above, in the conventional method the reaction ratio of silane and caustic soda is usually 1:1 to 2 (silane:caustic soda), but in the case of the present treatment agent, Silane: Caustic soda = l: 1 to 1.6,
This treatment agent #i is superior to the wet absorption method in terms of high absorption and removal efficiency and effective use of caustic soda. In general, even with the wet absorption method, highly effective use of caustic soda can be achieved by optimizing the contact conditions between sila and caustic soda, but this requires complicated and expensive equipment and complicated operation management. Although there are problems such as, in the case of this treatment agent, the maximum effective use of caustic soda can be achieved without any conditions being set.

Next, it was experimentally confirmed that a more significant effect can be obtained by further impregnating the present treatment agent described above with an aqueous solution of an oxidizing agent. This will be explained below.

The oxidizing agent may be optional, but it is preferably a colored oxidizing agent, which changes color upon reaction. Impregnated with this oxidizing agent aqueous solution, it can absorb silane, diborane, and hydrogen selenide in the same way as the aforementioned treatment agent, and can also absorb germane.1 Furthermore, it has a remarkable effect on absorbing diborane and hydrogen selenide. Example 2 will be described below regarding the case where potassium permanganate is selected as the oxidizing agent.

[Example 2] Fill a cylinder with an inner diameter of 2 cm and a height of 50 cIIi with 100 g of the processing agent (+:0) shown in (a) below, and carry out the following case 1.
．． Implemented in case 2 and case 3.

Case 1 Nitrogen gas containing 10.5 Ls of Nijiran is supplied.

Case x2 Niji? Flow nitrogen gas containing 10.5% y and 5% dibora y.

Case 3 Flow nitrogen gas containing 5% Nigelman.

G) Treatment agent: Impregnate ±100 g of diatomaceous material with 150 g of 10% caustic soda solution.
Under the above operating conditions, the gas in each case was impregnated with 10 g.
Go (1/!1ain fi, silane in the exhaust gas within 60 minutes.The concentration of diborane and germane was measured and the results as shown in the table were obtained.

It can be seen that treatment with an excessive amount of the treatment agent (b), as shown in this example, is particularly effective in removing dirt and germane. In addition to the absorption effect of 9 or more, potassium permanganate has a strong oxidizing power in basic conditions such as caustic soda, which makes it suitable for use.As the oxidizing power decreases, the color changes from purple to green, brown, and then white. Therefore, breakthrough of the processing agent can be seen at a glance from the appearance.

As described above, the present invention has an extremely simple configuration, and
69 Relating to processing agents that can efficiently treat volatile inorganic hydrides and volatile inorganic halides such as silane, diborane, hydrogen selenide, and germane by dry absorption methods.
, its implementation effects are significant. In particular, when treating waste gas from semiconductor manufacturing processes, conventionally arsine and phosphine had to be treated dryly, and silane and diborane had to be treated wetly, but with the present invention, the treatment system can be unified to be dryly treated. Therefore, it is expected that not only the equipment will be simplified and the wrinkles reduced, but also labor saving will be achieved.

Claims (1)

[Scope of Claims] 1. A volatile inorganic hydride and a volatile inorganic 710 genide, characterized in that they are expressed by impregnating a solid carrier mainly composed of a porous inorganic silicate with an alkaline aqueous solution. Absorption treatment agent. 2. An absorption treatment agent for volatile inorganic hydrides and volatile inorganic halides, which is obtained by impregnating a mm carrier mainly composed of a porous inorganic silicate with an aqueous alkali solution and an aqueous oxidizing agent solution. 3. The absorption treatment agent according to claim 1 or 2, wherein the solid carrier whose main component is a porous inorganic silicate is diatomaceous.