JPH0710334B2 - NF3 Exhaust gas treatment method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for purifying NF ₃ exhaust gas generated in the production of semiconductors and liquid crystals to render it harmless.

[0002]

2. Description of the Related Art A CVD exhaust gas needs to be treated because it contains a large amount of unreacted process gas and harmful components produced by its decomposition.

Further, NF ₃ used for CVD cleaning is unreacted NF as cleaning exhaust gas.
₃ and SiF ₄ generated by the reaction are contained, and it is necessary to treat them to render them harmless.

Conventionally, the CVD exhaust gas treatment has been performed by an absorption method using a wet scrubber, an adsorption method using a solid adsorbent, a combustion method and the like. Wet absorption of NF ₃
Processes such as thermal decomposition + adsorption have been performed.

In the case of wet absorption, the removal rate of harmful gas is often low. Although the adsorption method has high removal efficiency, it requires replacement of the adsorbent and the decomposing agent, resulting in high running cost. The combustion method is effective for the treatment of CVD exhaust gas for combustible gas, but cannot treat the cleaning gas.

The present invention has a low running cost and a high harmful gas removal rate.

[0007]

The present invention is a processing method and apparatus described below and described above, by which the above problems can be solved.

An NF ₃ exhaust gas treatment method, characterized in that an exhaust gas containing NF ₃ is subjected to a thermal oxidative decomposition treatment, and NF ₃ remaining in the gas subjected to the thermal oxidative decomposition treatment is removed. NF ₃ gas processing apparatus characterized by comprising a NF ₃ remaining exhaust gas heat oxidation decomposing device and the heating oxidative decomposition gas from the abatement device for abatement process comprising NF _3.

In the present invention, exhaust gas containing NF _3, that is, NF ₃ exhaust gas (hereinafter, simply referred to as exhaust gas), means NF 3.
Any gas containing ₃ may be used, but it means, for example, exhaust gas in an apparatus using a cleaning gas containing at least NF ₃ in semiconductor manufacturing, and in addition to the exhaust gas of a process gas, the inside of the apparatus is cleaned with the cleaning gas. It is also meant to include reaction products of various NF ₃ generated as a result and the substance to be cleaned existing inside the apparatus. Therefore, in the present invention, NF ₃
The detoxification treatment is meant to include the detoxification treatment of the NF ₃ derivative.

According to the present invention, the exhaust gas is directly heated and oxidatively decomposed. In the exhaust gas derived from the process gas, substantially all of the organic part is CO ₂ and water, and the metal part is a metal oxide such as SiO ₂ . Fine particles, F ₂ and NO in NF ₃
Give rise to _X etc. Then, the treated gas is washed with water as desired to solubilize or entangle it to obtain fine particles, F ₂ ,
After removing SiF _{4 and the} like, it is passed through an NF ₃ detoxifying device filled with a detoxifying agent to remove residual NF ₃ , NO _x, etc., and obtain a harmless treated gas.

In the present invention, the exhaust gas is heated and oxidatively decomposed to detoxify the organic portion contained in the exhaust gas into water and CO ₂ , and most of NF ₃ , preferably 80% or more, is oxidized to obtain the latter stage. Since the treatment amount of unoxidized NF ₃ is drastically reduced, there is an advantage that the economical efficiency of NF ₃ treatment is improved.

The harmful agent used in the present invention is N
Any known F ₃ can be used as long as it has a function of preventing F _{3 from} being released into the environment as it is. To illustrate specific detoxifying agents, NF ₃ chemically reacts with the chemical detoxifying agent detoxifies NF ₃ by changing a part or all of NF ₃ to other compounds, physical and NF ₃ Examples of the physical detoxifying agents that are physically adsorbed and held, and combinations of these agents.

Examples of the chemical detoxifying agents include types that oxidatively decompose NF ₃ to change it into F ₂ and NO _X and chemically react with F _2, and preferably iron, manganese, copper, silicon, titanium and the like. A metal or its oxide is mentioned.

Examples of the physical detoxifying agent include silica, activated carbon, alumina, molecular sieve and the like. Form of該除harm agent is optional, on the yarn, powdered, other materials, for example, can use composite materials such as cellulose or the like, usually, the inlet and NF ₃ of the heating oxidative decomposition gas A detoxifying device can be configured by filling or loading a desired amount in a container provided with an outflow port for detoxified gas.

The temperature of the abatement device is preferably 300 ° C. or higher when a chemical abatement agent is used. This heating means is preferably heated by a heater or the like, but it can also be performed by heat exchange with the treated exhaust gas.

Further, the processing speed SV (flow rate) in the abatement device for the gas subjected to the thermal oxidative decomposition treatment is 2000 1 / h.
It is desirable to process in. A typical example of the device for discharging the exhaust gas in the present invention is a CVD device, and the exhaust gas is composed of a CVD exhaust gas derived from a process gas during the CVD process and / or a cleaning exhaust gas during the cleaning.

Examples of the process gas that provides the CVD exhaust gas include inorganic materials such as monosilane, disilane and dichlorosilane, and organic materials such as TEOS (tetraethoxysilane) and TMB (trimethoxyborane). And these are used alone or in combination. These exhaust gases include unreacted products or their derivatives, reaction decomposition products, such as alcohols such as H ₂ , CO and C ₂ H ₅ OH, and CH _3.
Aldehydes such as CHO and heat oxidatively decomposable substances such as hydrocarbons such as C ₂ H ₄ are included, and are mainly metal oxides such as SiO ₂ and H ₂ O and CO by being thermally oxidatively decomposed.
Become ₂ . It is clear that the thermal oxidative decomposition referred to here includes mere oxidization of non-decomposable substances, for example, oxidization of simple substances such as hydrogen and metals.

The cleaning exhaust gas is at least NF
₃ and substances in CVD equipment (unexhausted CVD-treated substances, etc.)
And a reaction product thereof, for example, SiF ₄ , an NF ₃ derivative and the like, and a cleaning gas and a substance in the CVD physically cleaned by the cleaning gas.

Other cleaning gases include CF ₄ ,
Such as _{C 2 F 6, SF 6,} ClF 3 and the like. The reaction conditions of the thermal oxidative decomposition treatment in the present invention, the introduction conditions of the exhaust gas, etc. are not particularly limited, but at least the thermal oxidative decomposable substance contained in the exhaust gas under the coexistence of oxygen may be thermally oxidatively decomposed. . Therefore, when introducing the exhaust gas into the thermal oxidation decomposition apparatus, it is necessary that oxygen be present in the thermal oxidation reaction section at the same time. The method of existence of this oxygen is arbitrary, but it is usually preferable to introduce the oxygen together with the exhaust gas as an oxygen-containing gas such as air. Further, any gas can be mixed in order to adjust the conditions of thermal oxidative decomposition. For example, it is preferable that an inert gas such as nitrogen is mixed and introduced into the reaction part of the thermal oxidative decomposition apparatus in a three-layer state in which the nitrogen gas wraps the exhaust gas and oxygen wraps them. It is preferable to provide a concentric tube having a three-layer structure as the gas introduction section.

Further, the heating means in the thermal oxidative decomposition treatment is also optional, but preferably the heater heating system capable of electrically controlling the temperature as described above is desirable, and it can be usually provided in the wall of the reaction section. The temperature of the reaction part is 8
The range of 00 to 1000 ° C. is preferable.

In the present invention, the exhaust gas which has been subjected to the heat oxidative decomposition treatment is transferred to a harm removing device for harming NF ₃ as it is, or after being subjected to any other treatment, it is transferred to the harm eliminating device according to its composition. Can be transferred.

Particularly, in the present invention, it is preferable that the exhaust gas subjected to the thermal oxidative decomposition treatment is brought into contact with water, that is, subjected to a water washing treatment, whereby the metal oxide fine particles such as SiO ₂ produced by the decomposition treatment. Can be removed by entanglement, water-soluble compounds such as SiF ₄ and F ₂ can be removed by solubilization, and the processing gas can be cooled. The method of this water washing treatment is arbitrary, but it is preferable to bring it into contact with the treatment gas in a spray form.

The NF ₃ detoxified product of the gas washed with water may be released into the environment or, if desired, may be subjected to any other desired treatment, such as a known adsorption treatment. For example, an exhaust pipe or the like can be provided in the abatement device. In addition, the washing drainage is discharged to the outside of the system by drainage means such as a drain pipe. These washing treatment means,
The discharge pipe and the like may be provided in the thermal oxidation decomposition apparatus or separately.

The present invention can be provided with a control device so that the above-mentioned processing steps can be continuously and automatically carried out as a series, and desired processing conditions can be appropriately selected. This control device is usually in communication with various detection devices, for example, sensors for temperature, pressure, water level, etc., and is constructed so as to be always safe and to perform optimum processing.

In the thermal oxidative decomposition method of the present invention, the exhaust gas is oxidatively decomposed at a high temperature so that the exhaust gas can be treated in a short time. , Air, nitrogen, and cooling water (which also serves as washing water) can be treated efficiently, so the running cost is lower than the dry adsorption method alone. Further, by connecting a heating oxidative decomposition apparatus and a water washing section (gas cooling, solid matter removal) and an NF ₃ detoxification apparatus as needed, the acidic gas was removed in the water washing section, and then it could not be decomposed by the heat decomposition apparatus. NF ₃ can be completely removed with an NF ₃ abatement device. Further, since about 80% of the introduced NF ₃ is removed by the thermal oxidative decomposition device, the load on the NF ₃ abatement device can be greatly reduced.

[0026]

The present invention relates to a CV containing an NF ₃ cleaning gas.
Exhaust gas discharged from the D process or the like is first treated with a thermal oxidation decomposition device. 800 ° C or higher with a thermal oxidative decomposition system 1
CVD exhaust gas such as silane and disilane and NF ₃ are oxidatively decomposed at 000 ° C. or lower.

Next, if desired, an acid gas such as hydrofluoric acid and SiO ₂ are removed in a water washing section. Finally, the CVD exhaust gas and the NF ₃ cleaning exhaust gas can be completely decomposed and removed by reacting and removing NF ₃ with a metal oxide or the like under the condition of preferably heating at 300 ° C. or higher in an NF ₃ removal device.

[0028]

EXAMPLE A specific example of the present invention will be described with reference to FIG. 1, but the present invention is not limited thereto.

FIG. 1 shows an example of a treatment apparatus used in the method of the present invention. The NF ₃ exhaust gas treatment apparatus 1 of the present invention comprises a thermal oxidative decomposition apparatus 2 and an NF ₃ detoxification apparatus 3.
The thermal oxidative decomposition apparatus 2 oxidizes an exhaust gas inflow pipe 4 for introducing the CVD exhaust gas from the CVD device, a nitrogen inflow pipe 5 for introducing nitrogen for adjusting the exhaust gas oxidation, and a thermally oxidative decomposable substance in the exhaust gas. A gas introduction part 7 having a three-layer structure in which an air inflow pipe 6 for supplying oxygen is concentrically formed, and a heat source for thermally oxidizing and decomposing exhaust gas in the mixed gas discharged from the gas introduction part. A reaction part 11 having a certain ceramic heater 8 on its outer wall and provided with thermocouples 9 and 10 whose temperature is controlled, and a process gas containing a heated oxidative decomposition product produced in the reaction part 11 are used as cooling water 1.
2 and F ₂ and SiF ₄ for washing with water at ₂
It is composed of a drain pipe 14 which discharges waste water containing soluble substances such as SiO _{2 and the} like to the outside of the system.

The NF ₃ abatement device 3 is a heating oxidative decomposition device 2
The processing gas, which is provided in the subsequent stage and is washed with water, is introduced into the NF ₃ abatement device 3 through the supply pipe 15. The NF ₃ abatement device 3 is filled with a metal oxide or the like for detoxifying the introduced gas such as NF ₃ to be detoxified, and purifies and detoxifies the exhaust gas by passing it. It is possible to discharge this from the exhaust pipe 16 provided.
In addition, 17 to 19 are sampling tubes A for exhaust gas, gas subjected to thermal oxidative decomposition / washing treatment, and gas subjected to catalytic treatment,
B and C.

[0031]

[Experimental Example] A processing test was conducted using the apparatus shown in FIG. The amount of exhaust gas containing NF ₃ and SiH ₄ is 40 L / min, and the treatment conditions of the thermal oxidative decomposition apparatus are reaction temperature 900 ° C. and N ₂ 1
0 L / min, oxidizing air 20 L / min, and cooling water 4 L / min. The reaction temperature of the NF ₃ abatement device was set to 300 ° C. The results are shown in Table 1. In the table, A, B, and C indicate sampled tubes.

[0032]

[Table 1]

As shown in Table 1, S in the thermal oxidation decomposition apparatus is
iH ₄ can be removed, and NF ₃ can be removed by 80 to 83%.
By treating the remaining NF ₃ with the NF ₃ removal device in the subsequent stage, exhaust gas generated from the CVD can be completely removed.

[0034]

The exhaust gas treatment method of the present invention makes it possible to reduce the running cost and remove harmful gases with high efficiency as compared with the conventional adsorption method. Further, the present invention is particularly effective when treating the exhaust gas of a single-wafer CVD apparatus in which the CVD exhaust gas and the cleaning exhaust gas are exhausted without being completely separated.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an NF ₃ exhaust gas treatment apparatus to which the method of the present invention is applied.

[Explanation of symbols]

1 NF ₃ Exhaust Gas Treatment Device 2 Heating Oxidation Decomposition Device 3 NF ₃ Detoxification Device 4 Exhaust Gas Inflow Pipe 5 Nitrogen Inflow Pipe 6 Air Inflow Pipe 7 Gas Introducing Section 8 Ceramic Heater 9 Thermocouple 10 Thermocouple 12 Cooling Water 13 Rinsing Section 14 Drainage Pipe 15 Supply pipe 16 Exhaust pipe 17 Sampling pipe A 18 Sampling pipe B 19 Sampling pipe C

─────────────────────────────────────────────────── ─── 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. A NF ₃ gas processing method characterized by heating oxidative decomposition of exhaust gas containing NF _3, to an abatement processes NF ₃ remaining in the heating oxidative decomposition treatment gas. 2. A NF, characterized in that it consists of a scrubber for abatement processes NF ₃ remaining exhaust gas heat oxidation decomposing device and the heating oxidative decomposition treatment gas containing NF _3
3 Exhaust gas treatment equipment.