JPH0714455B2 - Exhaust gas treatment device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust gas treatment apparatus, and more particularly to an exhaust gas treatment apparatus suitable for removing harmful components in semiconductor etching exhaust gas. More specifically, SF contained in the exhaust gas generated when sulfur hexafluoride and fluorocarbon-based CFCs are used for semiconductor etching.
_The present invention relates to an apparatus for efficiently removing harmful components such as ₄ , HF, SiF ₄ , WF ₆ , SO ₂ F ₂ , and SOF ₂ .

[Conventional technology and problems]

Recent progress in fine processing technology in the semiconductor industry has been remarkable, and the types of gases used have been diversified with the progress of this technology. Especially for semiconductor etching, fluorinated carbon such as CF ₄ , C ₂ F ₄ , C ₃ F ₈ , CF ₃ Cl, CF ₂ C
A large amount of various compounds containing halogenated fluorinated carbons such as l ₂ and CFCl ₃ , fluorinated hydrocarbons such as CHF ₃ and fluorine such as SF ₆ and WF ₆ are used.

Etching is performed by supplying a gas onto the material to be processed and causing a reaction by plasma or the like to generate a substance having a high vapor pressure and a substance having a high volatility. Therefore, the exhaust gas contains various substances, and harmful components are also present therein. For example, when SF ₆ is used, HF, SOF ₂ , SF _4, etc. are included.

For this reason, it is necessary to remove these harmful components from the etching exhaust gas before it is discharged out of the system. However, the actual situation is that there is no preferable processing apparatus until now. For example, a tower-type processing apparatus currently used is one in which the inside of the tower is filled with an adsorbent or a chemical that reacts with these harmful components, and the harmful components are removed by adsorption or chemical reaction. Since it is limited to one type, there is a drawback that only specific components can be removed. Therefore, the two towers,
Although the towers are arranged in series with the three towers and the type of packing is changed to remove all the harmful components in the exhaust gas, it is a large-scale device and the unit volume per clean room is similar. Not suitable for use in very expensive places. Furthermore, in such a method, a partial gas flow may occur, and not only the adsorbent or the chemical agent is not consumed on average, but there is also a risk that the harmful gas indicator does not operate and the harmful gas goes out of the system. There is.

Further, when the indicator is attached near the exhaust gas outlet, there is a problem that harmful gas has already exited the system when the indicator operates. for that reason,
Although an indicator with a sharp sensitivity is desired,
At present, there is still no satisfactory product.

[Object of the Invention]

An object of the present invention is to solve the problems of the conventional exhaust gas treating apparatus, to provide a compact apparatus for effectively removing harmful components contained in etching exhaust gas, and to provide a highly sensitive indicator used in this apparatus. .

[Details of Invention]

According to the present invention, the inside of the apparatus is divided into at least three chambers by a partition plate, the partition plate is provided with a gas flow port so that gas sequentially passes through each chamber, and at least one gas flow port is provided. This is an exhaust gas treatment device having a harmful gas indicator attached.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a structural diagram when the processing device is a cylindrical type.
Reference numeral 1 is a main body, and 2 is a partition plate. Exhaust gas flow is indicated by thick arrows. Exhaust gas is discharged from the gas inlet nozzle 3 at D
Enter the room. The chamber D is an oil mist collector chamber, which contains a fine stainless steel demister in some cases, and the oil mist is collected by deceleration. The gas from which the oil mist has been removed enters the S chamber through the gas flow port X ₁ . The S chamber is a chemical reaction chamber and is filled with a chemical that reacts with harmful gases, such as soda lime, a mixture of soda lime and alumina, and sodium sulfite-impregnated alumina.
It reacts with and removes SO ₂ F ₂ , SOF ₂ , WF ₆ , HF, etc. Chambers A and C are physical adsorption chambers filled with alumina, activated carbon, sodium sulfite impregnated alumina, and the like. S
The gas leaving the chamber passes through the gas flow ports X ₂ and X ₃ , enters the chamber A and then the chamber C, and after the inert gas such as SF ₅ and CF ₃ is adsorbed, the gas is discharged from the gas outlet nozzle 4 outside the system. Is discharged to.

11 and 12 are harmful gas indicators, which are at the outlet and A
It is installed at the gas flow port X ₃ on the boundary between the chamber and the C chamber. The indicator may be installed only at the gas outlet, but when the indicator is activated (discolored), there is a possibility that harmful gas has already exited the system, and the gas flow port between other chambers X ₁ It is also preferable to install at X ₂ and X ₂ .

In the figure, 5 and 9 are ball valves, 6 is a gas inlet pipe,
Reference numeral 7 is a gas outlet pipe, 8 is an outlet nozzle, 10 is a medicine inlet / outlet nozzle, 13 is a liquid level gauge, 14 is a hanging fitting, 15 is a caster, and 16 is a handle.

The indicator is composed of NaF pellets impregnated with promocresol green or bromthymol blue in an amount of 0.01 to 1 wt%, and rapidly changes color from yellow to blue when a gas with an HF concentration of 1 to 10 ppm comes into contact. Incidentally, the conventionally used indicator is generally one in which a pH indicator is impregnated in alumina, but alumina may react with components in the exhaust gas, so that the reaction is slow and the color changes once. However, there is a drawback that the color returns to the original with the passage of time. The indicators used in the present invention remedy these drawbacks.

When this indicator is activated (discolored), it indicates that the filled drug is at the end of its life. Therefore, in this case, the processing device is replaced with another processing device to replace the medicine. It is one of the advantages of the present invention that the replacement is easy because the processing apparatus itself is compact.

Although the present invention has been specifically described with reference to the drawings, the main body does not necessarily have to have a cylindrical shape, and may have a prismatic shape, a cubic shape, or a rectangular parallelepiped shape. Also, the chamber divided by the partition plate is an oil mist collector chamber, a chemical reaction chamber,
The physical adsorption chambers may not be arranged in order, and in some cases, either the chemical reaction chamber or the physical adsorption chamber may be omitted. However, it is preferable that the number of rooms is three or more. Moreover, since the etching is usually performed under vacuum (reduced pressure), a vacuum pump is used. Therefore, the oil used for this pump becomes mist and is contained in the exhaust gas, so the oil mist collector chamber is essential. It is preferable to set one room as the room.

Although this apparatus was invented for treating an etching exhaust gas, it can also be used for treating a gas containing a similar harmful component, for example, a chemical vapor deposition exhaust gas.

〔Example〕

Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1 The exhaust gas treating apparatus shown in FIG. 1 was used. This processing device is made of SUS 304, and has a cylindrical height of 500 mm and an inner diameter of 350 mm. Filled with stainless oil demister, S in chamber D
Soda lime in the chamber (Kishida Chemical Ltd., JIS 2 No. products), alumina A chamber (Sumitomo Chemical Co., activated alumina KHD-46), activated carbon was used (Takeda Pharmaceutical Co., Ltd., Shirasagi C _2x) to C chamber.

SF ₆ gas is one of the etching gases used for high integration and miniaturization of semiconductor integrated circuit elements. An example in which etching exhaust gas in this case is processed by the present exhaust gas processing apparatus will be described.

SF ₆ 200 ml / M was flown on a silicon substrate, plasma etching was performed for 6 months, and the effect of removing harmful substances by this exhaust gas treatment device was examined.

Table 1 shows the average composition of the gas at the inlet and outlet of the processing equipment after 6 months.
It was shown to.

As is clear from Table 1, the acidic component and the high molecular weight substance were well removed.

Further, the indicator (pre-indicator) attached in front of the gas outlet was discolored about 1 month earlier than the discoloration of the gas outlet indicator, and it was easy to set the timing of drug conversion.

In addition, as a comparative example, the same experiment was conducted using a pipe (internal diameter of about 19 cm) with the same cross-sectional area. I couldn't do it.

Further, the single-cylinder type has a shorter breakthrough curve in terms of the life of the drug, and the drug must be replaced while the drug cannot be fully utilized.

As is clear from the above description, this device can effectively use the medicine than the single-cylinder type, the breakthrough can be predicted by installing the pre-indicator, and there is no gas fragment flow in the indicator part, so the hue change of the indicator Has the advantage of being credible.

Example 2 For cleaning a tungsten silicide thin film forming apparatus
An example of exhaust gas treatment when SF ₆ / O ₂ gas is used will be described.

A mixed gas of SF ₆ 1,000 ml / M and O ₂ 200 ml / M was fed into the plasma CVD apparatus to clean the inside. This exhaust gas treatment device was attached to the CVD device outlet (vacuum pump Out side) and a test was conducted for 2 months. The results are shown in Table 2.

As is clear from this result, most of the gases other than SF ₆ and CF ₄ were removed.

The filling agent used at this time was a mixture of soda lime and alumina. (Fill S, A, C chambers).

Example 3 RIE (Reactive Ion Etching)
Exhaust gas treatment using CF ₄ and H ₂ as gas was performed using this exhaust gas treatment device.

The material of the wafer is SiO ₂ .

Table 3 shows the exhaust gas composition and the composition of the exhaust gas treatment apparatus outlet gas when etching was performed with 100 ml / M CF ₄ and 50 ml / M H ₂ .

Most of the harmful gases were removed by this treatment equipment, but only CO could not be removed.

The chemicals used in Example 3 were alumina (rooms A and C),
The implementation period for soda lime (S room) is 6 months.

[Brief description of drawings]

FIG. 1 is a structural view of the case where the processing apparatus is of the same cylinder type, FIG. 2 is a schematic cross-sectional view of the same, and FIG. 1 …… Main body, 2 …… Partition plate, 11 …… Indicator,
12 ... Indicator, D ... Oil mist collector chamber, S ... Chemical reaction chamber, A ... Physical adsorption chamber, C ... Physical adsorption chamber, X ₁ , X ₂ , X ₃ ... Gas flow port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B01D 53/34 ZAB

Claims (2)

[Claims] 1. The inside of the apparatus is divided into at least three chambers, one or more oil mist collector chambers, a chemical reaction chamber, and a physical adsorption chamber, by a partition plate, and the gas is sequentially passed through the partition plates. A semiconductor, characterized in that a gas flow port is provided, and that at least one gas flow port is provided with a harmful gas indicator made of sodium fluoride impregnated with bromocresol green or bromthymol blue. Etching exhaust gas treatment device. 2. The semiconductor etching exhaust gas treatment apparatus according to claim 1, wherein the chemical reaction chamber and the physical adsorption chamber are filled with any one of soda lime, alumina, activated carbon, and sodium sulfite-impregnated alumina.