JPH08257357A - Treatment method for nf3 gas and apparatus therefor - Google Patents

Abstract

PURPOSE: To provide a NF3 gas treatment method with which an apparatus can be miniaturized, treatment can be carried out safely, and electric consumption can be lowered. CONSTITUTION: A treatment cylinder 3 in which soda lime 2 is stored and a heat radiating cylinder 4 is installed is prepared and at the time when NF3 leaks out, the leaking NF3 is detected by a detecting apparatus 1 and based on the detected signal, the heat radiating cylinder 4 is heated. Then, the leaking NF3 gas is introduced into the treatment cylinder 3 and the NF3 gas is brought into contact with a heat radiating cylinder 4 in heated state to thermally decompose the NF3 and at the same time to absorb the substances produced by the decomposition in the soda lime 2 heated by the heat radiating cylinder 4 in the heating state.

Description

Detailed Description of the Invention

[0001]

The present invention relates to NF₃Gas as it is,
Or NF that removes the gas containing it ₃Place of gas
The present invention relates to a processing method and an apparatus used therefor.

[0002]

2. Description of the Related Art Dry etching gas for semiconductors or
Is generally used as a cleaning gas₃Used by gas
It is supposed to be done. That is, NF₃Gas atmosphere
Ionized NF in an electric discharge₃Siri with gas
The reaction products become volatile when etching
Therefore, the etching in the conventional fluorocarbon plasma
Weighing less than carbon (C) or sulfur (S)
There is no reaction residue contamination on the surface of the
Therefore, there is an advantage that the etching rate becomes faster. This
From the perspective of₃Gas is becoming more used
Is coming, but NF₃The gas is very stable at room temperature (but
Therefore, it is not decomposed even if it is released into the atmosphere
Very poisonous with a permissible concentration of 10 ppm
It is a sexual gas. From this, it can be installed in a cylinder box, etc.
NF paid₃Gas cylinder to NF ₃When gas leaks
At the same time, through the exhaust duct, into the atmosphere, NF₃Gas
It is dangerous if it is released as it is without being removed.
₃Gas processing becomes a big problem.

Therefore, in order to treat such NF ₃ gas, the following method is generally performed. That is, first, the NF ₃ gas is subjected to a heat treatment (that is, converted into F ₂ or HF by being thermally decomposed, or brought into contact with a metal at a high temperature to cause a reaction to convert into a gaseous metal fluoride. Then, after cooling the gas containing these decomposition products etc. to room temperature, it is passed through a soda lime adsorbent at room temperature or low temperature to physically adsorb the decomposition products etc. to remove them. Be seen.

[0004]

However, this method requires two steps, that is, a heat treatment for thermally decomposing the NF ₃ gas and an adsorption treatment for adsorbing the decomposition products produced by the heat treatment. The adsorption treatment is physical adsorption, and is performed at room temperature to a low temperature in order to exert the adsorption ability, so the treatment temperature is significantly different from the heat treatment,
Each requires a separate processor. Therefore,
Along with this, there is a problem that the entire device becomes complicated and large.

On the other hand, in heat treatment, NF₃High temperature gas
When reacting with metal, air is mixed in the processing equipment.
Then, the high temperature metal reacts with oxygen in the air,
NF ₃Since the reaction with gas does not proceed, the abatement capacity
Decrease early or reaction due to excessive oxidation reaction
If the temperature inside the device rises abnormally due to heat treatment and control becomes impossible
I have a problem. In addition, combustion associated with the abnormal temperature rise
NO as a by-product in the process_xProduce harmful substances such as
There is also a problem in terms of safety. That
Well, try to apply this method in case of emergency such as leakage.
In order to prepare for emergencies, it is always
It is necessary to keep the inside of the device at a high temperature.
Is wasted and becomes very uneconomical.

The present invention has been made in view of the above circumstances, and a method for treating NF ₃ gas and a device used therefor, which can realize downsizing of the device, is excellent in safety, and can reduce electric power cost and the like. The purpose is to provide.

[0007]

In order to achieve the above-mentioned object, the present invention provides a processing cylinder containing a heat-resistant adsorbent and a heating section inside, and at the time of NF ₃ gas leakage, this leakage occurs. NF ₃ gas is detected by the detector, as well as heating the heating unit based on the detection signal, to introduce leakage NF ₃ gas into the processing cylinder, NF ₃ in the heating section of the heating state
Contacting the gas causes thermal decomposition, the processing method of the NF ₃ gas so as to adsorb the degradation products in a heated state into a heated heat the adsorbent by the heating unit to a first aspect, the leakage NF ₃ gas A detector for detecting the temperature, a processing cylinder containing a heat-resistant adsorbent, a heating unit disposed in the processing cylinder and heated based on the detection signal, and an NF connected to one side of the processing cylinder. ₃ and a gas introduction pipe, comprising: a treated gas discharge pipe connected to the other side of the treatment column, and a control valve for introducing leakage NF ₃ gas into the NF ₃ gas introduction pipe on the basis of the detection signal NF The second gist is a processing device for ₃ gases.

[0008]

In other words, the inventors of the present invention have proposed a simple NF ₃ gas,
In the process of conducting a series of studies for the purpose of rapid detoxification, a heat-resistant adsorbent such as soda lime, which was conventionally used as an adsorbent at room temperature or low temperature, decomposes NF ₃ gas in a state of being heated to high temperature. At the same time, they have found that they have a characteristic of adsorbing the produced decomposition gas (which is considered to be chemisorption), and have reached the present invention. N according to the invention
In the method of treating F ₃ gas, the leaking NF ₃ gas is introduced into the treatment cylinder in which the heat-resistant adsorbent is housed and the heating portion is arranged therein, and the heating portion is heated. Then, the NF ₃ gas is brought into contact with the heating portion in this heating state to thermally decompose it, and the decomposition product is adsorbed to the heated heat-resistant adsorbent in the heating state. Therefore, the heat treatment and the adsorption treatment, which were conventionally performed in two steps, can be performed simultaneously, and the treatment apparatus can be simplified and downsized accordingly. In addition, since a heat-resistant adsorbent is used and a kind of chemisorption that adsorbs decomposition products in a heated state is utilized, even if air is mixed in the processing cylinder,
As in the conventional case, the detoxifying ability does not decrease and the temperature inside the apparatus does not rise abnormally. Moreover, since the abnormal Atsushi Nobori as described above it is prevented, without causing the harmful substances of the NO _x or the like as by-product in the combustion process, is also excellent in safety. In addition, since the leakage of NF ₃ gas is detected and heating is performed only when the detoxification process in an emergency is required, the processing cost of electricity and the like can be reduced and it is economical.

Further, in the processing method of the NF ₃ gas of the present invention, in the processing cylinder, when mixed accommodating a heating agent and heat the adsorbent to heat by contact with air, NF ₃ into the processing cylinder By introducing the gas, the exothermic agent comes into contact with the air in the exhaust gas to generate heat, and the NF ₃ gas is decomposed and the heat-resistant adsorbent is heated. This quickly heats the inside of the processing cylinder, shortening the startup time of the device,
If a leak occurs, it will be possible to respond promptly.

Next, the present invention will be described in detail.

According to the present invention, a heat-resistant adsorbent and a processing tube having a heating section provided therein are used to heat the heating section based on a detection signal from a detector for detecting leaked NF ₃ gas. The leaked NF ₃ gas is introduced into the processing cylinder, and the NF ₃ gas is brought into contact with the heating part in the heated state for thermal decomposition, and the decomposition product is adsorbed in the heated state to the heat resistant adsorbent heated by the heating part. Let

The heat-resistant adsorbent used in the present invention is NF
It is inert and stable to oxygen at the decomposition temperature of ₃ gases (300 ℃ -600 ℃), and moreover, in this temperature range, NF ₃
It is capable of chemically adsorbing F ₂ , HF, etc., which are decomposition products of gas, and is granular soda lime, Fe ₂ O ₃ , C at room temperature.
Examples thereof include granular soda lime supported on a metal oxide such as uO.

An electric heater is provided in the processing cylinder.
In addition to the heating part consisting of etc., usually by contact with air
An exothermic agent that generates heat is placed, and this exothermic agent and the soda
It is stored in a mixed state with Im and the like. This
NF₃When the exhaust gas containing gas is introduced into the processing cylinder,
The exothermic agent comes into contact with the air in the exhaust gas to generate heat, resulting in NF ₃
The decomposition of gas and the heating of soda lime will take place.
It Therefore, do not always heat the soda lime
Also NF₃Promptly remove soda lime only when removing gas.
Be able to heat.

As the exothermic agent, a reducing metal powder that is oxidized by oxygen and generates heat is used. Examples of the iron powder include nickel powder and titanium powder.

The heating temperature of the above soda lime is
It is desirable to set the temperature to 300 ° C to 600 ° C. That is, if the temperature is lower than the above temperature range, decomposition of the NF ₃ gas is unlikely to occur, and conversely, if the temperature is too high, corrosion of the processing cylinder itself rapidly progresses. In claims 1 to 5 of the present invention, the NF ₃ gas is a gas consisting of only NF ₃ gas and a gas (NF ₃
Exhaust gas including gas).

Next, examples will be described.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the NF ₃ gas treating apparatus of the present invention. In the figure, 10 is a steel rectangular cylindrical cylinder box in which the NF ₃ gas cylinder 11 is stored. Reference numeral 3 is a stainless steel processing cylinder having a circular cross section, and a stainless exhaust gas introducing pipe provided with an electric first control valve 7 and a first blower 16 on one side (the left side in the drawing) of the upper side thereof. 5 is connected, and the processing cylinder 3 is
The exhaust gas introducing pipe 5 communicates with the lower portion of the cylinder box 10. The cylinder box 10
The lower portion of, when the leakage of the NF ₃ gas is generated, the detector 1 is mounted for detecting the leakage NF ₃ gas. This detector (Riken Keiki Co., Ltd., potentiostatic electrolysis detector)
On the basis of the detection signal of No. 1, the first control valve 7 is opened and the control valve 18 is closed, so that the exhaust gas containing the leaked NF ₃ gas in the cylinder box 10 is processed into the processing cylinder 3
It is supposed to be introduced inside. A treated gas discharge pipe 6 for discharging the exhaust gas treated in the treatment cylinder 3 is connected to the lower side of the other side of the treatment cylinder 3.

As shown in FIG. 2, a plurality of stainless steel cylindrical heat generating cylinders 4 are inserted into the processing cylinder 3 at predetermined intervals, and the upper and lower ends of these heat generating cylinders 4 are The ceiling wall and the bottom wall of the processing cylinder 3 are opened with a predetermined space maintained. In addition, inside the heating cylinder 4,
It is filled with a powdery heat generating agent (iron powder is used in this embodiment) 8 which generates heat by contact with air. The granular soda lime 2 is placed inside the processing cylinder 3.
And the same exothermic agent 8 as described above are stored in a mixed state. On the upper surface of the ceiling wall of the processing cylinder 3, a conical stainless steel lid 12a provided with an air introducing pipe 13 on its upper part is hermetically sealed, and at the same time, the processing cylinder 3 is covered. Similarly to the lower surface of the bottom wall, the lid 1
Similar to 2a, a bottom body 12b with an air exhaust pipe 14 is attached. Then, the air introduced from the air introducing pipe 13 flows through each of the heat generating tubes 4 from the top to the bottom in the drawing. In addition, a second control valve (the same as the first control valve 7) 1 is opened in the air introduction pipe 13 based on a detection signal from the detector 1.
5 is provided, and the air exhaust pipe 14 is also provided with the detector 1
A second blower (the same as the first blower 16) 17 that operates based on the detection signal of (1) is provided. As a result, when the leakage of NF ₃ gas occurs, the heating cylinder 4
Air is circulated in the inside and brought into contact with the heat generating agent 8 inside to generate heat. An electric heater 9 that is heated based on a detection signal from the detector 1 is arranged in the center of the processing cylinder 3.

In the above structure, the exhaust gas containing NF ₃ gas is treated as follows. That is, first, the leakage of the NF ₃ gas is generated from the NF ₃ gas cylinder 11 in the cylinder box 10. The leakage NF ₃
The gas is detected by the detector 1. Then, based on this detection signal, the heating of the heater 9 is started, the second control valve 15 is opened, the second blower 17 is further operated, and air is circulated in the heating cylinder 4. The exothermic agent 8 inside is made to generate heat. Due to this heat generation, the heat generating cylinder 4 is quickly heated. Further, simultaneously with the heating of the heating cylinder 4, the first control valve 7 is opened and the control valve 18 is closed based on the detection signal of the detector 1, so that the leakage NF ₃ in the cylinder box 10 is generated. Exhaust gas containing gas,
It is introduced into the processing cylinder 3 through the exhaust gas introduction pipe 5. As a result, the exothermic agent 8 in the processing cylinder 3 comes into contact with the air in the exhaust gas to generate heat, and the soda lime 2 mixed with the exothermic agent 8 is heated.
Is quickly heated. On the other hand, NF ₃ in the exhaust gas is decomposed by contact with the heating cylinder 4 and soda lime 2 in the heated state and is decomposed, and the decomposition product is chemically adsorbed by the heated soda lime 2 to be removed. It
Further, after the exothermic reaction of the exothermic agent 8 housed in the processing cylinder 3 and the exothermic agent 8 filled in the exothermic cylinder 4 is finished, the heater 9 is heated to remove harm by the same action as described above. Done.

As described above, in this NF ₃ gas treatment method, the leaking NF ₃ gas is introduced into the treatment cylinder 3, the heating cylinder 4 is heated, and the NF ₃ gas is brought into contact with the heating cylinder 4 in the heated state. In addition to the thermal decomposition, the decomposition products are adsorbed to the soda lime 2 in the processing cylinder 3 in a heated state. Therefore, the heat treatment and the adsorption treatment can be performed at the same time, and the treatment device can be simplified and downsized. Further, since soda lime 2 which is inactive to oxygen is used and a kind of chemisorption effect of adsorbing decomposition products in a heated state is utilized, even if air is mixed into the processing cylinder 3, Since the oxygen in the air and the soda lime 2 do not react with each other, the detoxifying ability is not lowered and the abnormal temperature rise in the processing cylinder 3 does not occur. Moreover, since the abnormal Atsushi Nobori as described above it is prevented, without causing the harmful substances of the NO _x or the like as by-product, is also excellent in safety. Besides, N
Since the leakage of F ₃ gas is detected and heating is performed only when the detoxification process in an emergency is required, the processing cost of electric power can be reduced and it is economical.

Further, in the above-mentioned embodiment, the discharge is provided in the processing cylinder 3.
Since the heating agent 8 and soda lime 2 are mixed and stored,
By introducing the gas into the processing cylinder 3, the exothermic agent 8 generates heat,
NF ₃Gas decomposition and soda lime 2 heating
It As a result, the inside of the processing cylinder 3 is quickly heated and the apparatus
Start-up time is shortened, and leaks etc. are quickly
You will be able to respond. Furthermore, heater 9
Since it is used together, an abnormal situation such as leakage has occurred for a long time
Therefore, even after the heat generation of the heat generating cylinder 4 is finished,
You can continue to make sense.

FIG. 3 shows a processing cylinder according to another embodiment of the present invention. In this embodiment, the heater 9 is not used, and one heating tube 19 is inserted inside the processing tube 18.
An air introducing pipe 20 and an air exhausting pipe 21 are provided on the upper and lower surfaces of the heating cylinder 19, respectively. Other than that, it is the same as that shown in FIG. 1, and the same portions are denoted by the same reference numerals. Also in this embodiment, the same effect as that of the above embodiment is obtained.

[0023]

As described above, according to the method for treating NF ₃ gas of the present invention, the heat treatment and the adsorption treatment, which were conventionally performed in two steps, can be simultaneously performed, and accordingly, the treatment apparatus can be installed. It can be simplified and miniaturized. Also,
Since it uses a kind of chemisorption that adsorbs decomposition products in a heated state by using a heat-resistant adsorbent, even if air is mixed in the processing cylinder, the detoxifying ability is the same as before. It does not drop or the temperature inside the device does not rise abnormally.
Furthermore, since abnormal temperature rise is prevented as described above,
It is also excellent in safety because it does not generate harmful substances such as NO _x which is a by-product in the combustion process. In addition, since the leakage of NF ₃ gas is detected and heating is performed only when the detoxification process in an emergency is required, the processing cost of electricity and the like can be reduced and it is economical.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an NF ₃ gas treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a processing cylinder.

FIG. 3 is an explanatory view showing a processing cylinder of another embodiment.

[Explanation of symbols] 1 detector 2 soda lime 3 processing cylinder 4 heating cylinder

Claims (5)

[Claims] [Claim 1] preparing a heat-resistant adsorbent treatment cylinder heating unit disposed therein is accommodated, when NF ₃ gas leak, detects this leakage NF ₃ gas detectors, based on the detection signal while heating the heating section, to introduce leakage NF ₃ gas into the processing cylinder, NF ₃ in the heating section of the heating state
A method for treating NF ₃ gas, characterized in that a decomposition product is adsorbed in a heated state to a heat-resistant adsorbent heated by the heating section while contacting the gas for thermal decomposition. 2. A heat-generating adsorbent and a heat-resistant adsorbent, which generate heat upon contact with air, are mixed and contained in the processing cylinder.
The NF ₃ gas treatment method described. _3. The method for treating NF ₃ gas according to claim 1 or 2, wherein the heat-resistant adsorbent is soda lime, and the exothermic agent that generates heat upon contact with air is iron powder. 4. A detector for detecting leaked NF ₃ gas, a processing cylinder containing a heat-resistant adsorbent, a heating unit arranged in the processing cylinder and heated based on the detection signal, and the processing described above. The NF ₃ gas introduction pipe connected to one side of the cylinder, the treated gas discharge pipe connected to the other side of the treatment cylinder, and the leakage N to the NF ₃ gas introduction pipe based on the detection signal.
An NF ₃ gas treatment device, comprising a control valve for introducing F ₃ gas. 5. A heat-generating agent that generates heat when contacted with air and a heat-resistant adsorbent are mixed and accommodated in the processing cylinder.
The NF ₃ gas treatment device described.