JPH0741145B2 - Etching exhaust gas removal method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of removing etching exhaust gas.

[Prior Art] Conventionally, an abatement device for removing toxic and corrosive gases has been used mainly in the semiconductor industry.

However, the chemical reaction agent and the adsorbing agent are deactivated and saturated depending on their respective capacities by the detoxifying gas, so that the harmful gas may permeate (break through) during continuous treatment. Therefore, it is necessary to detect breakthrough in advance, and as a known technique, a method of measuring the amount of adsorbed gas by weight to detect breakthrough (see JP-A-61-68536),
A method of detecting breakthrough by a color reaction with a reaction reagent is known.

[Problems to be Solved by the Invention] The conventional gravimetric method has a drawback that the breakthrough cannot be accurately detected because the amount of gas that can be processed varies depending on the history of the same kind of drug. Further, the abnormal heat generation of the drug or the like due to the mixing of water or the like cannot be detected by the gravimetric method. In the method using the color reaction, it is difficult to automate the device because the detection is inevitably invisible to human eyes. Also, abnormal heat generation cannot be detected. The present invention was made for the purpose of eliminating these drawbacks and accurately detecting abnormal heat generation and breakthrough.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and a filling containing a chemical reaction agent capable of chemically reacting with halogen or a halogen compound to fix these. In layers,
This is a method of introducing and removing the etching exhaust gas containing halogen or halogen compounds, in which a heat detector is installed near the etching exhaust gas outlet to raise the temperature due to the reaction heat of the etching exhaust gas and the chemical reactant, and to introduce it into the packed bed. The temperature rise due to the abnormal heat generation due to the reaction between the water and the chemical reaction agent is measured, and the fact that the temperature rise due to the abnormal heat generation is higher than the temperature rise due to the reaction heat is used to distinguish the abnormal heat generation from the breakthrough of the packed bed. The present invention provides a method of removing etching exhaust gas that is separately detected.

With the recent high integration of semiconductors, the progress of fine processing technology is remarkable. Particularly, a dry etching technique using a halogen compound is frequently used to form a fine pattern. However, BCl ³ and CCl are contained in the dry etching exhaust gas.
_{4, Cl 2, SiCl 4,} HCl, COCl 2, F 2, COF 2, toxicity such as HF, includes a gas halogens or halogen compounds having corrosion resistance, removing these gases per etching apparatus Is desirable. The present invention detects breakthrough and abnormal heat generation of the abatement device in advance by detecting the heat of chemical reaction or the heat of adsorption between the packed bed containing the chemical reactant and the etching exhaust gas when removing these gases with a heat detector. It is a method of detecting, and it is preferable to detect the breakthrough using another means in the apparatus in advance and record the temperature at that time.

FIG. 1 attached herewith shows a cross-sectional view of a typical example of the apparatus used in the present invention. Etching exhaust gas is PT from the equipment inlet 1.
After passing through the insert tube 2 made of FE (polytetrafluoroethylene), the packed bed 3 rises, is rendered harmless, and is discharged from the mounting outlet 4. It is desirable that the outer wall 5 and the inner wall 6 of the filling container have a small thermal conductivity so that the heat generation zone in the filling layer due to the heat of the chemical reaction is narrowed, and the inner wall 6 is preferably one that can withstand corrosive exhaust gas. , Synthetic resin as outer wall, especially fiber reinforced synthetic resin (FRP), and inner wall as PTF
It is preferable to adopt E.

As the heat detector provided in the vicinity of the etching exhaust gas outlet of the packed bed 3, a heat-sensitive paper or the like that can be visually determined may be used, but after detection, a heat medium such as a thermocouple, bimetal, or oil that can output a signal to the outside. It is effective to use thermal expansion, infrared rays, a blow fuse, or the like. The location of the heat detector may be in the vicinity of the etching exhaust gas outlet in the packed bed (7 in FIG. 1) or in the inner wall or outer wall of the packing container near the etching exhaust gas outlet of the packed bed. When it is installed in the packed bed, it is preferable to use a heat detector with corrosion resistance such as PTFE. If the installation position of the heat detector is close to the exhaust gas outlet, it can be detected immediately before the breakthrough, and if it is far away, the breakthrough can be predicted earlier.

As the chemical reactant, oxides, hydroxides, silicates, or carbonates of alkaline earth metals, carbonates of alkali metals, or oxides of iron group, chromium group elements or the like are preferable. Specifically, magnesium oxide, magnesium hydroxide, magnesium carbonate, basic magnesium carbonate, calcium oxide, calcium silicate, sodium carbonate, sodium bicarbonate, iron oxide, chromium oxide and the like. You may use these 2 or more types simultaneously. Not only the chemical reaction agent but also an adsorbent can be used together. As the adsorbent, activated carbon,
Activated alumina, silica gel, zeolite and the like are preferable,
Two or more of these may also be used simultaneously.

In general, the heat of adsorption from an adsorbent is smaller than the heat of reaction from a chemical reactant, so when using an adsorbent in a packed bed, the adsorbent and the chemical reactant may be mixed or a heat detector may be used. It is preferable to concentrate the chemical reaction agent in the packed bed near the installation position in a concentrated manner. In order to make it easier to detect the heat of adsorption heat or reaction heat with a heat detector, it is important that the heat generation amount is large and that the adsorption and reactivity are excellent so that the heat generation zone in the packed bed is narrowed. It is preferable to select the type of such adsorbent or chemical reaction agent or a combination thereof.

[Operation] The present invention has a feature that it is possible to accurately detect the breakthrough time in removing exhaust gas and to automatically issue a breakthrough alarm. This is because when the exhaust gas passes through the abatement device, the exhaust gas is removed by the chemical reaction agent while generating heat, and this heat generation does not occur in the entire device in steady operation, only the part where the chemical reaction occurs. This is because heat is generated in the heat generation zone, and this heat generation zone gradually moves from the upstream portion to the downstream portion with respect to the flow of the exhaust gas as the cumulative passage amount of the exhaust gas increases. That is, the filler on the upstream side of the heat generation zone has already passed through, and if the heat detector is installed at the most downstream side of the packed bed, the breakthrough of the abatement device can be detected.

The width of the invention zone depends on the reaction performance of the chemical reaction agent, and the higher the reactivity, the faster the reaction is completed and the narrower the exothermic zone. That is, the breakthrough detection sensitivity is increased. Further, in the present invention, even when a large amount of water is introduced into the detoxification device and the filler causes abnormal heat generation, it can be detected separately from breakthrough. This is because such an abnormal heating value is so large that it cannot be compared with the heat of reaction between the halogen or the halogen compound and the chemical reactant during steady operation, and the heat is entrained in the passing gas to raise the temperature of the entire device. This is because when the temperature rise is sufficiently higher than the temperature rise temperature due to reaction or adsorption during steady state, it can be detected separately from breakthrough.

[Example] "Example of breakthrough detection" The reagents used for the test are as follows. Particle size 2-3m
MgO, Mg (OH) ₂ , CaO, Na ₂ CO ₃ , Fe ₂ O ₃ , FeO of m, activated carbon with a particle size of 4-6 mm, 0.5 vol% of F ₂ in nitrogen (all the following% are vol
%) Mixed gas, mixed gas containing 2% BCl ₃ in nitrogen, mixed gas containing 1% HCl in nitrogen, mixed gas containing 1% Cl ₂ in nitrogen, 1% HF in nitrogen A mixed gas containing 1% SiCl ₄ in nitrogen. The abatement device used in the test was a PTFE-lined FRP tube having an inner diameter of 350 mm and a height of 1030 mm.

In Examples 1,3,7,9,11, respectively, MgO is filled so as to have a layer thickness of 800 mm, F ₂ / N ₂ mixed gas, BCl ₂ / N ₂ mixed gas, HCl / N ₂ mixed gas, HF / N ₂ gas, SiCl ₄ mixed gas every minute
The test was carried out by flowing from the bottom with 10 l (room temperature 25 ° C). The temperature was measured by attaching a chromel-alumel thermocouple to the outer wall of the abatement system at a packed bed height of 680 mm.

In Example 5, activated carbon was filled so as to have a layer thickness of 800 mm, and a Cl ₂ / N ₂ mixed gas was flown from the bottom at a rate of 10 l / min (room temperature 25 ° C.) for testing. The temperature was measured by the same method as described above. This example was carried out for comparison with Example 4, and is not included in the present invention.

In Examples 2, 10 and 12, MgO from the bottom 650 mm,
On top of that, CaO was filled in 50 mm, MgO was further filled in 100 mm, and the total thickness was 800 mm. Each of them was mixed with F ₂ / N ₂ , HF / N ₂ and SiCl ₄ / N ₂ gas at a rate of 10 l / min (room temperature 25
The test was conducted by pouring from the bottom at (° C). The temperature was measured by the same method as described above.

In Example 4, MgO was 650 mm from the bottom and Na ₂ CO was deposited on top of it.
₃ was filled with 50 mm, MgO 100 mm, and a total thickness of 800 mm were used. BCl ₂ / N ₂ mixed gas was flown from the bottom at 10 l / min (room temperature 25 ° C.) for the test. The temperature was measured by the same method as described above. Example 5
Compared with, the measured temperature was higher and breakthrough could be detected more easily.

In Example 6, activated carbon was 650 mm from the bottom and F was placed on top of it.
eO was filled in 50 mm, and activated carbon was further filled in 100 mm so as to have a total thickness of 800 mm. A Cl ₂ / N ₂ mixed gas was flown from the bottom at 10 l / min (room temperature 25 ° C.) for the test. The temperature was measured by the same method as described above.

In Example 8, MgO was 650 mm from the bottom, and Mg (O
H) ₂ was filled to 50 mm, and MgO was further filled to 100 mm to a total thickness of 800 mm. A test was conducted by flowing an HCl / N ₂ mixed gas at a rate of 10 l / min (room temperature 25 ° C.) from the bottom. The temperature was measured by the same method as described above.

As a result, the breakthrough can be reliably detected by the detection temperatures shown in Table-1, no harmful gas is transmitted, and
The packed bed could also be used up to near saturation.

[Example of Abnormal Heat Generation Detection] It is considered that the cause of the abnormal heat generation is mainly due to the water content in the air. Therefore, in Examples 13 and 14, F ₂ was added in nitrogen.
A mixed gas containing 0.5% of BCl ₃ and a mixed gas containing 2% of BCl ₃ in nitrogen at 10 l / min (room temperature 25 ° C.) for 100 hours respectively, and reacted with the treated gas up to near breakthrough, and then the absolute humidity 1.5
% Air was inhaled at a rate of 500 l / min, and the temperature inside the packed bed at a height of 680 mm was measured. For temperature measurement, a chromel alumel thermocouple placed in a stainless protective tube was used. As a result, the abnormal heat generation detection temperature was much higher than the breakthrough detection temperature, and it was possible to easily distinguish between the breakthrough and the abnormal heat generation.

[Effects of the Invention] The method for detecting breakthrough and abnormal heat generation due to reaction heat according to the present invention is excellent in that it is possible to detect breakthrough and abnormal heat generation extremely sensitively with few malfunctions and further automate detection alarms and risk avoidance processing. It has advantages and is effective in removing exhaust gas from safety and driving operability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an etching exhaust gas abatement apparatus used in the present invention. 3 ... Packed bed 7 ... Heat detector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-51-35675 (JP, A) JP-A-54-95968 (JP, A)

Claims (4)

[Claims] 1. A method for removing harm by introducing an etching exhaust gas containing a halogen or a halogen compound into a filling layer containing a chemical reactant capable of chemically reacting with a halogen or a halogen compound to fix them. A heat detector is provided near the etching exhaust gas outlet to measure the temperature rise due to the reaction heat of the etching exhaust gas and the chemical reactant, and the temperature rise due to abnormal heat generation due to the reaction between the water introduced into the packed bed and the chemical reactant, An etching exhaust gas abatement method that distinguishes between abnormal heat generation and breakthrough of a packed bed by utilizing the fact that the temperature rise due to abnormal heat generation is higher than the temperature rise due to reaction heat. 2. The chemical reaction agent is an alkaline earth metal oxide, an alkaline earth metal hydroxide, an alkaline earth metal carbonate, an alkali metal carbonate, an iron group element oxide, or a chromium group. The method for removing etching exhaust gas according to claim 1, which is selected from the group consisting of oxides of elements. 3. The method for removing etching exhaust gas according to claim 1, wherein a heat detector is provided near the etching exhaust gas outlet in the packed bed. 4. The method for removing etching exhaust gas according to claim 1, wherein the heat detector is provided on the inner wall or the outer wall of the filling container near the outlet of the etching exhaust gas of the filling layer.