JPH09877A - Treatment agent of nitrogen trifluoride gas - Google Patents

Abstract

PURPOSE: To safely remove harmful components even if there is air component without causing abnormal temperature rise or generation of NOx and also to simplify the process to miniaturize a processing device. CONSTITUTION: A soda-lime in the form of granules or powder is provided, and the soda-lime, in a heated state, is brought into contact with NF3 gas or gas containing NF3 gas to decompose the NF3 gas so that the decomposed products of the NF3 gas can be adsorbed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NF ₃ gas treating agent which removes the NF ₃ gas as it is or the gas containing it.

[0002]

2. Description of the Related Art Dry etching gas for semiconductors or
Is generally used as a cleaning gas_ThreeUsed by gas
It is supposed to be done. That is, NF_ThreeGas atmosphere
Ionized NF in an electric discharge_ThreeSiri 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 of_ThreeGas is becoming more used
Is coming, but NF_ThreeThe 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 used for cylinder boxes, etc.
NF paid_ThreeGas cylinder to NF _ThreeWhen gas leaks
At the same time, through the exhaust duct, into the atmosphere, NF_ThreeGas
It is dangerous if it is released as it is without being removed.
_ThreeGas 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, the gas containing these decomposition products and the like is cooled to room temperature, and then passed through an adsorbent at room temperature or low temperature to physically adsorb the decomposition products and remove them.

[0004]

However, in this method, in the case where NF ₃ gas is reacted with a high temperature metal in the heat treatment, if air is mixed in the treatment apparatus, the high temperature metal will react with oxygen in the air. Since it reacts and the reaction with NF ₃ gas does not proceed, the detoxification capacity is reduced at an early stage, or the reaction heat due to excessive oxidation reaction causes an abnormal temperature rise in the equipment, making it uncontrollable. There is a problem of doing. Further, in the combustion process accompanied by the abnormal temperature rise, a harmful substance such as NO _x may be produced as a by-product, which causes a problem in safety. Further, a two-step treatment of a heat treatment for thermally decomposing the NF ₃ gas and an adsorption treatment for adsorbing a decomposition product generated by the heat treatment is required, and the adsorption treatment is a physical adsorption and has an adsorption ability. Since it is performed at room temperature or low temperature in order to exert the above effect, the treatment temperature is significantly different from the heat treatment, and a separate treatment device is required for each. Therefore, there is a problem that the entire apparatus becomes complicated and large in size accordingly.

The present invention has been made in view of such circumstances, and even if it contains an air component, it is possible to safely remove harm without generating an abnormal temperature rise or NO _x, and also to simplify the process. It is an object of the present invention to provide a treatment agent for NF ₃ gas that can be made into a compact size and can realize a compact processing apparatus.

[0006]

In order to achieve the above object, the present invention comprises soda lime formed in the form of particles or powder, and is NF ₃ gas or NF _{3 in} a heated state.
By contacting a gas containing gas, the NF ₃ gas is decomposed and the decomposition product is adsorbed.

[0007]

In other words, in the process of conducting a series of studies for the purpose of safe and simple detoxification of NF ₃ gas, the present inventors have found that soda lime, which is generally used as a CO ₂ or water absorbent, The inventors have found that the present invention has the property of decomposing NF ₃ gas and adsorbing the produced decomposition gas (presumed to be chemisorption) at the same time when it is heated to a high temperature, and reached the present invention. The treatment agent for NF ₃ gas according to the present invention comprises soda lime formed in a granular or powder form, and decomposes and decomposes the NF ₃ gas by contacting with NF ₃ gas or a gas containing it in a heated state. The product is adsorbed. Thus, this treatment agent is a strongly basic soda lime mainly composed of a metal hydroxide, which is inert to oxygen, even if air is mixed in the treatment device, as in the conventional case, The detoxifying ability does not decrease, and the temperature inside the device does not rise abnormally. Further, since the abnormal temperature rise is prevented, no harmful substances such as NO _x which is a by-product in the combustion process are generated, which is also excellent in safety. In addition, this treatment agent utilizes a kind of chemisorption that adsorbs decomposition products in a heated state, rather than physical adsorption that is effective only in the normal temperature range or low temperature range as in the past. The heat treatment and the adsorption treatment, which were performed in two steps, can now be performed at the same temperature and at the same time. With this, the treatment process can be simplified and the treatment device can be simplified and downsized. become able to.

When the soda lime is soda lime carrying a metal oxide, there is an advantage that the treatment temperature can be lowered. Furthermore, when the temperature in the heated state is 300 ° C. to 600 ° C., it is possible to efficiently decompose the NF ₃ gas and prevent damage due to corrosion of the processing apparatus itself.

Next, the present invention will be described in detail.

The treatment agent for NF ₃ gas of the present invention is NF ₃
Are stable in inert to oxygen in the gas decomposition temperature (300 ° C. to 600 ° C.), moreover, this temperature range, its degradation products decompose NF ₃ gas in contact with the NF ₃ gas F _It can chemically adsorb ₂ and HF, and is granular or powdery soda lime at room temperature, or Fe ₂ O ₃ , Cu.
Soda lime supporting a metal oxide such as O is used.

The soda lime can be obtained, for example, as follows. That is, first, quicklime is dipped in an alkaline solution such as sodium hydroxide, then, this is kneaded and formed into particles or powder by extrusion molding or the like to obtain soda lime mainly composed of metal hydroxide. . Further, the soda lime supporting the metal oxide is obtained by immersing the metal oxide and quicklime in an alkaline solution such as sodium hydroxide, and then kneading in the same manner as above to form a granular or powdery form. .

The temperature of the soda lime thus obtained in a heated state is preferably set to 300 ° C to 600 ° C, more preferably 400 ° C to 500 ° C. That is, when the temperature is lower than the above temperature range, decomposition of the NF ₃ gas is hard to occur, and when the temperature is too high, corrosion of the processing apparatus itself rapidly progresses.

The NF ₃ gas to which the present invention is applied refers to both a gas consisting of only the NF ₃ gas and a gas in which air or the like is mixed (exhaust gas containing the NF ₃ gas).

The NF ₃ gas treating agent of the present invention is used, for example, in a treating apparatus as shown in FIG. This processing apparatus uses a soda lime 2 and a processing tube 3 in which a heating tube 4 is arranged, and heats the heating tube 4 based on a detection signal from a detector 1 that detects leaked NF ₃ gas. At the same time, the leaked NF ₃ gas is introduced into the processing cylinder 3, and the NF ₃ gas is brought into contact with the heat generating cylinder 4 in the heated state and the soda lime 2 heated by the heat generating cylinder 4 to thermally decompose the soda lime. 2 is for adsorbing decomposition products in a heated state.

The above processing device will be described in more detail.
In the figure, 10 is NF inside _ThreeGas cylinder 11
It is a square tubular cylinder box made of steel to be stored. Three
Is a stainless steel processing cylinder with a circular cross section, one side of which
On the upper side (on the left side of the figure), the electric first control valve 7 and
And exhaust gas made of stainless steel provided with the first blower 16
The introduction pipe 5 is connected, and the processing cylinder 3 is connected to the exhaust gas guide pipe.
Through the inlet pipe 5, the lower part of the cylinder box 10 and
It is in communication. On the lower side of the cylinder box 10
Is NF_ThreeWhen a gas leak occurs, this leak NF_Three
Gas detector (Riken Keiki Co., Ltd., potentiostatic electrolysis type detector
Intellectual Property) 1 is attached. Detection signal of this detector 1
The first control valve 7 is opened based on the
When the control valve 18 is closed in the cylinder box 10,
Leakage NF_ThreeIntroduce an exhaust gas containing gas into the processing cylinder 3.
It has become so. In addition, on the lower side of the other side of the processing cylinder 3,
Indicates that the exhaust gas processed in the processing cylinder 3 is exhausted
The gas discharge pipe 6 is connected.

As shown in FIG. 2, a plurality of stainless steel cylindrical heat generating cylinders 4 are inserted through the processing cylinder 3 at a predetermined interval, and the upper and lower ends of the 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. As the exothermic agent 8, a reducing metal powder that is oxidized by oxygen to generate heat is used. In addition to iron powder, nickel powder, titanium powder, or the like may be used.

The exhaust gas containing NF ₃ gas is treated by the above treatment apparatus 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 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, when the treating agent for NF ₃ gas of the present invention is mixed with the powdery or granular exothermic agent 8 which generates heat by contact with air in the treating apparatus, NF ₃ gas is used. By introducing the exhaust gas containing the gas into the treatment device, the exothermic agent 8 generates heat by contacting the air in the exhaust gas, and the decomposition of the NF ₃ gas and the heating of the soda lime 2 are simultaneously performed. As a result, the inside of the processing apparatus and the soda lime 2 are quickly heated, the start-up time of processing is shortened, and it becomes possible to promptly deal with leakage and the like. In addition, since the NF ₃ gas can be heated only when an emergency detoxification process is necessary when it leaks, the processing cost of electric power can be saved and it is economical.

[0019]

As described above, according to the NF ₃ gas treating agent of the present invention, since it is a strongly basic soda lime mainly composed of a metal hydroxide, it is inert to oxygen, and if Even if air is mixed into the processing device, the detoxifying ability does not decrease or the temperature inside the device does not rise abnormally as in the conventional case. Further, since the abnormal temperature rise is prevented, no harmful substances such as NO _x which is a by-product in the combustion process are generated, which is also excellent in safety. In addition, this treatment agent utilizes a kind of chemisorption that adsorbs decomposition products in a heated state, rather than physical adsorption that is effective only at room temperature or low temperature as in the past, so that it is conventionally used. It becomes possible to perform the heat treatment and the adsorption treatment, which were performed in stages, at the same temperature and at the same time, so that the treatment process can be simplified and the treatment device can be simplified and downsized. become.

Next, examples will be described together with comparative examples.

[0021]

Examples 1-3 Air containing 1.1% NF ₃ gas (Example 1), air containing 2.0% (Example 2) and 1.3%
Air containing air (Example 3) was treated at a treatment temperature of 400 to 5 by the treatment apparatus shown in FIG. 1 using the treatment agent of the present invention.
The detoxification treatment was performed under the treatment conditions of 00 ° C. and a flow rate SV of 25 to 51 liters / hr. The results are shown in Table 1 below.

[0022]

[Table 1]

From the results shown in Table 1 above, with the treatment agent of the present invention, NF ₃ gas was 5 ppm at any concentration.
It can be seen that the following (gas chromatography detection limit) has been processed. Further, in Examples 1 to 3 above, the detoxification process could be performed without causing an abnormal temperature rise in the processing apparatus.

[0024]

COMPARATIVE EXAMPLE The treatment was performed by the conventional two-step treatment method in which air containing the same concentration of NF ₃ gas as in Example 1 was brought into contact with a high temperature metal. As a result, abnormal temperature rise, which is thought to be due to the oxidation of the agent, occurred, and the treatment was impossible immediately.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a processing apparatus in which a processing agent for NF ₃ gas of the present invention is used.

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Hamaguchi 2-6-6 Chikko Shinmachi, Sakai City, Osaka 40 Daido Hokusan Co., Ltd.

Claims (3)

[Claims] 1. A soda lime formed in a granular or powder form, which decomposes the NF ₃ gas and adsorbs the decomposition product by contacting with NF ₃ gas or a gas containing NF ₃ gas in a heated state. NF characterized by
₃ gas treatment agent. 2. The treatment agent for NF ₃ gas according to claim 1, wherein the soda lime is soda lime carrying a metal oxide. 3. The temperature in a heated state is 300 ° C. to 600 ° C.
The NF ₃ gas treating agent according to claim 1 or 2.