JP3318340B2 - Scrubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scrubber for treating exhaust gas from a normal pressure CVD apparatus. More specifically, the present invention relates to a scrubber for treating hardly soluble materials contained in exhaust gas from a state CVD apparatus.

[0002]

2. Description of the Related Art One of the methods widely used in the semiconductor industry as a method of forming a thin film is a chemical vapor deposition (CVD) method.
position). CVD means that a gaseous substance is converted into a solid substance by a chemical reaction and deposited on a substrate.

[0003] The characteristics of CVD are that various thin films can be obtained at a deposition temperature considerably lower than the melting point of the thin film to be grown, and that the grown thin film has high purity and is grown on Si or a thermal oxide film on Si. In this case, since the electrical characteristics are stable, it is widely used as a passivation film on a semiconductor surface.

The formation of a thin film by CVD is, for example, about 400
A reaction gas (eg, SiH ₄ + O ₂ or SiH ₄ + PH ₃ + O ₂ ) is applied to a wafer heated to about 500 ° C. to 500 ° C.
Is performed. The reaction gas is blown onto a wafer in a reaction furnace (bell jar), and Si
O ₂ or phosphosilicate glass (PSG),
A thin film of borosilicate glass (BSG) and / or borophosphosilicate glass (BPSG) is formed. Further, it can be used for forming a metal thin film such as molybdenum, tungsten or tungsten silicide.

Since SiH ₄ (monosilane) gas reacts explosively when it comes into contact with oxygen in the air, it must be handled with great care. For this reason, recently, when forming a SiO ₂ film, instead of SiH ₄ (monosilane) gas, liquid tetraethoxy silicate (TEO) which is easy to handle is used.
S) has come to be used.

[0006] Even if a raw material for film formation such as TEOS is supplied to a reaction furnace of a normal pressure CVD apparatus, only 10% or less of the input raw material is actually used for the reaction, and the remaining 90% or more of the raw material is reacted. It is mixed with exhaust gas from the furnace and discharged out of the furnace.

There is no problem if the components such as unreacted TEOS contained in the exhaust gas from the reactor are completely harmless to the human body and the environment. Adversely affect Therefore, it cannot be directly discharged into the atmosphere.

Conventionally, exhaust gas from a reactor has been discharged into the atmosphere through a scrubber 1 as shown in FIG. Exhaust gas from a reactor (not shown) is sent into scrubber 1 by duct 3. Scrubber 1
A primary filter 5 for removing solid foreign matter such as SiO ₂ is provided therein. Exhaust gas sent into the scrubber via the duct 3 passes through the primary filter 5,
After the solid foreign matter is removed, washing water is sprayed from a shower nozzle 7 provided above the filter. The fine flakes that have passed through the filter come into contact with the water in the form of mist, are captured in water droplets, and fall. These water droplets are stored in a storage tank 9 below the filter 5. When the storage tank 9 is full,
Open the lower valve 11 and discharge the waste liquid.

However, hardly hydrolyzable materials such as unreacted TEOS in the exhaust gas cannot be removed by the water scrubber 1. For this reason, it is further sent out to the filter unit 17 through the pipe 15 by the fan mechanism 13 disposed above the scrubber. This filter unit 17
Inside, for example, one or more activated carbon filters 19 are provided. Poorly soluble organic substances that do not hydrolyze, such as TEOS, are captured by the activated carbon filter. Exhaust gas from which flakes and TEOS have been removed is supplied to the fan mechanism 21.
And finally discharged to the factory exhaust system through the duct 23.

Unfortunately, since the exhaust gas from the reactor of the atmospheric pressure CVD apparatus contains a large amount of flakes such as SiO ₂ , the finer flakes that have passed through the primary filter of the scrubber generate this activated carbon. The filter is clogged in a short period of time, and the filtration efficiency of the poorly soluble organic substance is significantly reduced. Frequent replacement of the activated carbon filter increases running costs and is uneconomical. Also, CV
It is not at all possible to split the exhaust gas from the D device according to the material.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a scrubber capable of treating hardly hydrolyzable organic substances which are difficult to hydrolyze, such as TEOS.

[0012]

According to the present invention, there is provided a scrubber for treating exhaust gas from a reactor of an atmospheric pressure CVD apparatus, wherein the scrubber is provided with an anionic surfactant from a shower nozzle. Disclosed is a scrubber capable of spraying an agent and / or nonionic surfactant-containing washing water.

The washing water containing an anionic surfactant and / or a nonionic surfactant preferably further contains an antifoaming agent.

[0014]

As described above, the scrubber of the present invention sprays cleaning water containing an anionic surfactant and / or a nonionic surfactant on exhaust gas from a reactor of a CVD apparatus. This makes it possible to dissolve poorly hydrolyzable organic substances such as TEOS in the exhaust gas in the scrubber cleaning water.

[0015]

The present invention will be described in more detail with reference to the following examples.

The anionic surfactant and the nonionic surfactant used in the scrubber of the present invention are generally preferably those having 20 or less carbon atoms.

Specifically, examples of the anionic surfactant which can be used in the present invention include fatty acid monocarboxylates (eg, sodium laurate) and N-acyloyl glutamates (eg, sodium nauroyl glutamate). Carboxylic acid types such as; alkyl benzene sulfonates (eg, sodium dodecyl benzene sulfonate), naphthalene sulfonate-formaldehyde condensates and dialkyl sulfosuccinates (eg, sodium 2-ethylhexyl sulfosuccinate) and the like. Sulfonic acid type; sulfate ester type such as alkyl sulfate (eg, sodium dodecyl sulfate); alkyl polyoxyethylene sulfate (eg, dodecyl polyoxyethylene sulfate) and alkyl phosphate (eg, monophosphate) Sodium Urirurin acid) and the like phosphoric acid ester type surfactants, such as.

The nonionic surfactants usable in the present invention include, for example, glycerin fatty acid esters (for example, glycerin monostearate), sorbitan fatty acid esters (for example, sorbitan monostearate), and sucrose fatty acid Ester types such as esters (eg, sucrose stearates); polyoxyethylene alkyl phenyl ethers (eg, polyoxyethylene nonyl phenyl ether), polyoxyethylene alkyl ethers (eg,
Ether types such as dodecyl polyoxyethylene ether), and polyoxyethylene polyoxypropylene block copolymers; polyethylene glycol fatty acid esters (eg, polyethylene glycol oleate) and polyoxyethylene sorbitan fatty acid esters (eg, polyoxyethylene sorbitan) Ester-ether type surfactants such as monopalmitic acid ester); and alkanolamide type surfactants such as fatty acid alkanolamide (eg, lauric acid diethanolamide).

The mixing amount of the anionic surfactant or the nonionic surfactant in the washing water is not particularly limited, but as a general index, 0.05 wt% to 5.0 wt%, preferably 0.2 wt%. ２．０2.0 wt%. If the amount is less than 0.05% by weight, the effect of dissolving the hardly soluble material becomes insufficient. On the other hand, if the compounding amount exceeds 5.0% by weight, the dissolving effect is saturated and not only becomes uneconomical, but also wastewater treatment requires a large cost, and furthermore, the foaming becomes too strong and hinders the workability of the scrubber. The result is not preferable. The anionic surfactant and the nonionic surfactant can be used alone or in combination. Several kinds of surfactants can be mixed and used.

It is known that washing water consisting only of water does not foam when sprayed, but washing water containing a surfactant foams when sprayed. Therefore, when selecting a surfactant, it is necessary to consider foaming properties in addition to solubility. By using a surfactant that generates a small amount of foam, the inside of the scrubber does not become full of foam. If the inside of the scrubber is full of bubbles, the contact between the poorly soluble material and the washing water is inhibited, and the dissolving effect is reduced.

There is no problem when a surfactant having a low foaming property can be used, but a surfactant having a high foaming property must be used depending on the type of the hardly soluble material.
In addition, a surfactant having a low foaming property must be used at a high concentration, and the amount of foam generated may increase. In order to solve such a situation, an antifoaming agent can be used if desired. Antifoaming agents that can be used in the present invention are, for example, polysiloxane-based antifoaming agents having 20 or less silicon atoms and 40 or less carbon atoms. The amount of the antifoaming agent is not particularly limited. In consideration of factors such as the foaming property and the blending amount of the selected surfactant, the blending amount that can provide a necessary and sufficient defoaming effect may be appropriately selected. The amount of such an antifoaming agent can be easily determined by those skilled in the art by repeating experiments.

The non-hydrolyzable and sparingly soluble material in the CVD exhaust gas which can be suitably treated with the surfactant-containing cleaning water of the present invention is, in addition to the above-mentioned TEOS, TMB (trimethylboron) and TEB (triethylboron). ), TMOP (trimethoxyphosphate) and TMP (trimethylphosphate). These poorly soluble CVD
The scrubber waste liquid in which the material has been dissolved is treated by a separate waste liquid treatment system (not shown) to a degree that satisfies a predetermined water quality standard, and is finally disposed of.

[0023]

As described in the foregoing, according to the scrubber of the present invention, non-hydrolyzable, such as unreacted TEOS contained in the exhaust gas from the atmospheric pressure CVD apparatus TEOS-O ₃ based Can be dissolved.
Therefore, the exhaust from the CVD apparatus can be performed without a significant change in the building facility. In addition, it is not necessary to use a filter unit using an activated carbon filter, which has been conventionally used for processing unreacted TEOS or the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of a scrubber used for processing exhaust gas from a normal pressure CVD apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scrubber 3 Duct 5 Primary filter 7 Shower nozzle 9 Waste liquid storage tank 11 Valve 13 Fan mechanism 15 Pipe 17 Filter unit 19 Activated carbon filter 21 Fan mechanism 23 Duct

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 47/06 B01D 53/18 B01D 53/46

Claims (2)

(57) [Claims] 1. Exhaust gas from a reactor of a normal pressure CVD apparatus
The exhaust gas is passed through a primary filter to treat
Spraying cleaning water on exhaust gas that has passed through the primary filter
From the primary filter and the washing water spray mechanism
In this scrubber, the exhaust gas is tetraethoxysilicate (TEO).
S), trimethylboron (TMB), triethylboron
(TEB), trimethoxy phosphate (TMOP) and
And trimethyl phosphate (TMP)
At least one non-hydrolyzable sparingly soluble material selected
The washing water spray mechanism contains an anion from a shower nozzle.
0.0-based surfactant and / or nonionic surfactant
A scrubber characterized by spraying washing water containing 5 wt% to 5.0 wt% . 2. The method according to claim 1, wherein the washing water is an anionic surfactant.
0.2% to 2.0% by weight of nonionic surfactant
The scrubber according to claim 1, wherein the scrubber is contained .