JP3366454B2 - Exhaust gas treatment agent - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment agent for exhaust gas containing an inorganic group V compound such as phosphine and arsine discharged from a III-V group compound semiconductor thin film manufacturing process. Currently, inorganic group V compounds are industrially used for MOCVD (M
etal Organic Chemical Vapo
rphase Deposition) method, or M
OVPE (Metal Organic Vapor)
GaA indispensable for manufacturing light emitting diodes, semiconductor lasers, etc. by the phase epitaxy method etc.
It is used when forming a compound semiconductor thin film of s, AlGaAs, InP or AlGaAsP. here,
The total amount of the inorganic group V compound supplied to these devices is not effectively utilized, and a part of the inorganic group V compound is discharged as it is to the outside of the system. These inorganic group V compounds in the exhaust gas are highly toxic and must be completely removed. The present invention is
In particular, it relates to a treating agent suitable for treating the inorganic group V compound in the exhaust gas.

[0002]

2. Description of the Related Art III-V group compound semiconductor thin films such as GaAs are indispensable for the recent demands for high-speed electronic devices and low power consumption, and for progress of optronics due to advances in optical technology. Is the material of. As a method of forming a thin film of a compound semiconductor, (A) MOCV
D, (B) MOVPE, (C) MBE (Molecul
ar Beam Epitaxy), (D) Halide C
There are VD etc. Among these, (A) MOCVD and (B) MOVPE do not need to be kept in a high vacuum in the crystal chamber, the raw materials are easily exchanged, and maintenance is easy, so that the frequency of use is high, and the crystals that have recently attracted attention. It is a growth method.

In the crystal growth of these, conventional III
Organometallic compounds such as trimethylaluminum and triethylindium have been used as the group raw material, and phosphine and arsine which are inorganic hydrides have been used as the group V raw material. The proportion of these inorganic hydrides, phosphine and arsine, fixed to the crystal is low, and III
Since a large amount of group V raw material is used for the group raw material,
A considerable amount of phosphine and arsine, which are inorganic hydrides, are entrained in the exhaust gas. As is well known, phosphine and arsine are highly toxic. For example, the minimum poisoning amount of arsine gas is 0.
Since it is 38 ppm, it is necessary to treat the exhaust gas.

III-using these inorganic hydrides
As a treatment agent for exhaust gas from the Group V compound thin film manufacturing process,
Cartridge-type ones have been put into practical use by filling a stainless steel container with a treatment agent containing copper oxide as a main component or a material obtained by impregnating a caustic alkaline solution in silicate clay or the like. These dry treatment methods are recognized to be effective in treating inorganic V hydrides such as phosphine and arsine contained in exhaust gas. There is also an advantage that the cartridge can be easily replaced.

As a wet treatment method, there is a method of spraying or flowing a solution containing silver nitrate, silver perchlorate, a water-soluble copper compound and caustic alkali into a packed tower. But,
The wet method is difficult to be adopted in the production of the III-V group compound thin film because of the risk that water droplets and moisture, which are repelled, will be back-diffused and flow back into the MOCVD and MOVPE apparatus main bodies and pipes. In recent years, I
Demand expanded due to the good performance of II-V compound thin films,
As a result, the amount of inorganic group V hydrides such as phosphine and arsine used is also increasing. V as a cause of large usage
The / III ratio is as large as 10 to 1000. The V / III ratio refers to the molar ratio of the group V compound and the group III compound, and the ratio changes depending on the type of the group III-V compound thin film. Ratio is an important factor that defines thin film performance.

The phosphine and arsine raw materials are usually supplied from the high-pressure gas cylinder to the point of use. Since phosphine and arsine are highly toxic, when these gases are used as raw materials, it is necessary to prevent leakage in the unlikely event and to reliably treat the exhaust gas. Therefore, conventionally, for the treatment of exhaust gas containing an inorganic group V compound, a treating agent containing copper oxide as a main component, which is highly effective against phosphine and arsine, which are inorganic hydrides, has been used.

[0007]

The chemical reaction between copper oxide and an inorganic hydride is an exothermic reaction. When the exhaust gas from the compound semiconductor thin film manufacturing process is treated with a cartridge filled with a treating agent containing copper oxide as a main component, the temperature of the outer wall of the cartridge is abnormally increased. Usually, hydrogen is used in the compound semiconductor thin film manufacturing process, and since hydrogen is also contained in the exhaust gas, the temperature rise of the processing agent is extremely dangerous. Should a hydrogen explosion occur, the secondary damage caused by the leakage of phosphine and arsine will be great as well as the primary damage caused by the explosion.

The inventor of the present invention has conducted a search for a component which is effective for an inorganic group V compound and has a small heat generation as a treating agent for treating exhaust gas, and as a result, basic copper carbonate was found to be effective against an inorganic group V compound. It was found to be extremely effective and generate little heat. Although the basic copper carbonate decomposes into copper oxide, the heat of decomposition is endothermic, so that the heat generated by the copper oxide and the inorganic hydride can be absorbed and the heat generated can be suppressed as a whole.

The present invention solves the above-mentioned problems in exhaust gas treatment based on this finding, and in treating exhaust gas from MOCVD or MOVPE in which an inorganic group V compound is present, it generates less heat as a whole and is safely treated. It is an object of the present invention to provide a treatment agent capable of performing

[0010]

According to the present invention, an exhaust gas treating agent for treating exhaust gas containing an inorganic group V compound discharged from a III-V group compound semiconductor thin film manufacturing process is used. It is composed of basic copper carbonate which is treated by immobilizing a group compound by a chemical reaction. Basic copper carbonate
A fine exhaust gas treating agent can be obtained by using fine particles having an average particle diameter of 0.5 μm or less.

[0011] In the preparation of the salt based on copper carbonate treatment agent of the present invention, the order to perform efficiently heat absorption, require different control for the improvement of solid-gas contact efficiency. In general, basic copper carbonate is produced by adding a solution of sodium carbonate to a solution of copper sulfate or cupric chloride to make the pH neutral to weakly basic, removing contaminating ions with water, filtering and drying. Has been prepared. However, in order to prepare a basic copper carbonate suitable for the treating agent of the present invention, the pH at which the basic copper carbonate is deposited, the temperature, the respective concentrations of the sodium carbonate solution and the copper sulfate or cupric chloride solution, and It is necessary to strictly control the method of adding the sodium carbonate solution and the copper sulfate or cupric chloride solution, as well as the kind and the amount of seed added.

The performance as a basic copper carbonate for the present invention is as follows:
In order to achieve high solid-gas contact efficiency, it is required that the average particle diameter by the centrifugal light transmission method is 0.5 μm or less, preferably 0.3 μm or less. Furthermore, in order to absorb the heat generated by the reaction between the inorganic group V compound and copper oxide and facilitate the conversion of basic copper carbonate to copper oxide, the molecular formula CuCO ₃ · Cu (OH) ₂ known as peacock stone is used. Also contains a large amount of OH groups, the content of which is 1.1 or more of the theoretical amount, 1.6
It is also required to be 1.2 or more and 1.5 or less.

As a method for achieving an average particle size of 0.5 μm or less, fine particles may be finely pulverized during the reaction of the copper compound and sodium carbonate, or fine particles may be finely pulverized by wet or dry pulverization. However, if the reaction is made finer, the load of the washing process will increase,
It becomes virtually impossible to operate. Even if it can be operated, there are problems that the yield will be extremely low, the removal of entrapped ions will be insufficient, or the unit consumption of water will be significantly high.

To make the particles finer to 0.5 μm or less, a wet grinding using a grinding medium having a large specific gravity and excellent in abrasion resistance and having a high concentration of basic copper carbonate is suitable.
In order to make the basic copper carbonate high in concentration, it is necessary to increase the bulk density of the basic copper carbonate, but when the basic copper carbonate is deposited, the seed type and addition amount, the sodium carbonate solution and the copper sulfate, The bulk density can be increased by adjusting the respective concentrations of the cupric chloride solution and the addition method of the sodium carbonate solution and the copper sulfate or cupric chloride solution.

When the content of OH groups is 1.7 or more, the content of copper hydroxide in the basic copper carbonate becomes relatively large, and the basic copper carbonate itself becomes unstable, so that the room temperature and the atmosphere are increased. It spontaneously decomposes, or decomposes by drying at a high temperature during the manufacturing process, or partially decomposes when basic copper carbonate is precipitated in the reaction. On the other hand, when the ratio is 1.0 or less, the basic copper carbonate is stable, but the decomposition temperature is high and the heat of decomposition is low, which is not suitable as a treating agent.

The content of the OH group controls the pH value during the reaction of the copper compound and sodium carbonate, reduces the pH fluctuation during the reaction, and avoids making the pH value from neutral to acidic. And can be adjusted by maintaining the reaction temperature at 60 to 70 ° C. The treating agent of the present invention is used by adding a small amount of an adhesive to a fine powder of basic copper carbonate and molding it into pellets or spheres. Further, the size of the molded body may be such that the contact area of the exhaust gas can be as wide as possible when packed in a packed tower and used, but in general, in the packed tower in order to prevent uneven flow of gas, It is said that the size needs to be smaller than 1/10.

[0017]

The treating agent of the present invention treats the inorganic group V compound in the exhaust gas discharged from the III-V group compound semiconductor thin film manufacturing process by immobilizing it with a basic copper carbonate by a chemical reaction.
The heat generated during the reaction is small and the temperature rise can be suppressed to allow safe processing. Since the inorganic group V compound in the exhaust gas is treated by a chemical reaction, it is not desorbed from the treatment agent later, unlike the treatment by physical adsorption.

[0018]

【Example】

Example 1 Water was added to a basic copper carbonate powder having an average particle diameter of 0.28 μm and an OH content of 1.18 times the theoretical value, water was sufficiently kneaded, and then dried to form spherical particles having a diameter of 1 to 2 mm. Molded. 2 in a Pyrex glass tube with a diameter of 26 mm
46 g was filled, and hydrogen gas was used as a carrier gas to 0.2
Mol phosphine at 50 ml / min (linear velocity 9.4
cm / min).

At this time, the amount of filler required for the treatment is 80 g.
Therefore, no phosphine was detected at the column outlet. The maximum exothermic temperature was 76 ° C. Example 2 Water was added to a basic copper carbonate powder having an average particle size of 0.35 μm and an OH content of 1.38 times the theoretical value, water was sufficiently kneaded, and then dried to form spherical particles having a diameter of 1 to 2 mm. Molded. 2 in a Pyrex glass tube with a diameter of 26 mm
24g is filled and hydrogen gas is used as a carrier gas to 0.2
mol arsine 50ml / min (linear velocity 9.4c
m / min).

At this time, the amount of filler required for the treatment was 68 g.
Therefore, arsine was not detected at the column outlet. The maximum heat generation temperature was 67 ° C. (Comparative Example 1) Commercially available copper oxide was molded into particles having a diameter of about 1 to 2 mm, which was filled in a Pyrex glass tube having a diameter of 26 mm, and the same experiment as in Example 1 was performed.

At this time, the amount of filler required for the treatment was 50 g and the maximum exothermic temperature was 175 ° C. (Comparative Example 2) Commercially available copper oxide was molded into particles having a diameter of about 1 to 2 mm, which was filled in a Pyrex glass tube having a diameter of 26 mm, and the same experiment as in Example 2 was performed. At this time, the amount of the filler required for the treatment was 55 g and the maximum exothermic temperature was 160 ° C.

The detection of arsine and phosphine in Examples and Comparative Examples was carried out using an arsine and phosphine detector tube manufactured by Komei Chemical Co., Ltd. Minimum detection concentration is 0.0
It is 5 ppm.

[0023]

As described above, according to the exhaust gas treating agent of the present invention, the exhaust gas containing the inorganic group V compound discharged in the III-V group compound semiconductor thin film manufacturing process is heated at a low temperature. The rise can be suppressed and processed safely.

Continuation of front page (56) Reference JP-A-60-68034 (JP, A) JP-A-5-269339 (JP, A) JP-A-5-269347 (JP, A) JP-A-6-319945 (JP , A) JP 61-296268 (JP, A) JP 62-152515 (JP, A) JP 5-123567 (JP, A) JP 5-184858 (JP, A) JP 6-327931 (JP, A) JP 7-136451 (JP, A) JP 7-171336 (JP, A) JP 8-10563 (JP, A) JP 8-24574 (JP, A) JP 8-29411 (JP, A) JP 8-155258 (JP, A) JP 8-173759 (JP, A) JP 8-192024 (JP, A) JP 8 -206444 (JP, A) JP 11-197509 (JP, A) JP-B 4-19886 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C30B 1/00- 35/00 B01D 53/34 H01L 21/205 CA (STN) REGISTRY (STN) WPI (DIALOG)

Claims (3)

(57) [Claims] 1. An exhaust gas treating agent for treating an exhaust gas containing an inorganic group V compound discharged from a III-V group compound semiconductor thin film manufacturing process, wherein an inorganic group V compound present in the exhaust gas is chemically reacted. Basic carbonic acid to be immobilized and treated
Exhaust gas treatment agent consisting of copper . 2. The average particle size of basic copper carbonate is a centrifugal type light.
The exhaust gas treating agent according to claim 1, which has a diameter of 0.5 μm or less as measured by a permeation method . 3. The content of hydroxyl groups in basic copper carbonate is
1.1 or more of the theoretical amount of child formula CuCO ₃ · Cu (OH) ₂
The exhaust gas treating agent according to claim 1 , wherein the treating agent is 1.6 or less .