JPH0664041B2 - Boron trichloride detection agent and breakthrough detection method for boron trichloride adsorption device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a boron trichloride detection agent and a breakthrough detection method for a boron trichloride adsorption device.

In recent years, in the semiconductor industry, for example, when dry etching aluminum or the like, boron trichloride is used alone as a dry etching gas, or boron trichloride and carbon tetrachloride, halogenated hydrocarbons such as carbon tetrafluoride, and chlorine gas. A mixed gas with other components such as halogen gas is used.

Since the above gases cause environmental pollution, their emission into the atmosphere is strictly regulated. Especially boron trichloride,
In addition to the above environmental problems, contact with air produces B ₂ O ₃ powder, which can accumulate and cause blockages in the outlet of oil rotary pumps and duct piping. Therefore, especially boron trichloride, aside from environmental concerns, needs to be reliably trapped before it produces B ₂ O ₃ powder.

Generally, in the case of dry etching or the like, after dry etching is performed by continuously contacting an object to be treated with boron trichloride or a gas containing boron trichloride, the waste gas discharged from the dry etching apparatus is treated with activated carbon or the like. A method is used in which a gas component to be adsorbed is removed through a gas adsorption device filled with an adsorbent and the gas discharged from the adsorption device is further released into the atmosphere through an alkali scrubber or the like.

In a gas adsorption device filled with such an adsorbent, when the adsorbent adsorbs a certain amount of substance, it breaks through and cannot adsorb more substances. If the gas to be adsorbed further flows into the gas adsorption device that has passed through, the gas to be adsorbed will not be adsorbed by the adsorbent and will flow out from the gas outlet.

Usually, when the waste gas after performing dry etching with a boron trichloride-containing gas is flowed to the adsorption device as described above to perform adsorption, the gas adsorption device is operated to remove chlorine contained in the boron trichloride-containing waste gas. Breakthrough for hydrogen gas and then for boron trichloride. Among these, hydrogen chloride gas can be easily absorbed and removed later by a known alkali treatment.

[Prior Art and its Problems] As a conventional method for detecting breakthrough of a gas adsorption device,
A method is used in which an acid gas (gas that becomes acidic when dissolved in water) detection agent (indicator) is attached to the adsorbent near the gas outlet of the gas adsorption device, and breakthrough is detected by the change in the hue of this indicator. ing.

Since this detection agent is sensitive to hydrogen chloride, in dry etching using a boron trichloride-containing gas, the gas adsorption device breaks through the hydrogen chloride gas at the point when the gas adsorption device breaks through. Therefore, the adsorption device has sufficient adsorption performance for boron trichloride at this point.

Hydrogen chloride gas, etc. flowing out from the gas adsorption device before the breakthrough of boron trichloride can be easily removed by using an alicarisclava etc. that is installed in a normal gas adsorption device. If the breakthrough of the device with respect to boron trichloride can be selectively detected, the gas adsorption device can be effectively used for a long time.

[Means for Solving the Problems] It is an object of the present invention to provide a detection agent capable of reliably detecting a trace amount of boron trichloride without being disturbed by hydrogen chloride gas, chlorine gas and the like. .

A further object of the present invention is to provide a method for detecting breakthrough of boron trichloride in a gas adsorption device such as a dry etching waste gas adsorption device using this detection agent.

The present invention relates to a boron trichloride detecting agent in which carminic acid, hydrochloric acid and sulfuric acid are supported on a carrier.

In addition, the present invention, a detection agent for boron trichloride, which is obtained by supporting carminic acid, hydrochloric acid and sulfuric acid on a carrier, is filled in the vicinity of the gas outlet of a boron trichloride adsorption device filled with an adsorbent, The present invention relates to a breakthrough detection method for a boron trichloride adsorption device, which is characterized in that breakthrough is detected by the coloration of.

The boron trichloride detecting agent of the present invention can be obtained by causing a carrier to carry a detecting solution comprising carminic acid, hydrochloric acid and sulfuric acid.

The sulfuric acid used in the present invention is not particularly limited as long as it is 70% by weight or more, but concentrated sulfuric acid (98% by weight) is usually used.

Carminic acid is generally used by dissolving it in concentrated sulfuric acid. The ratio of carminic acid and concentrated sulfuric acid to be used is not particularly limited, but 0.05 to 2.00% by weight, preferably 0.1 to 1.0% by weight of concentrated sulfuric acid is used.

As hydrochloric acid, dilute hydrochloric acid (35% by weight hydrochloric acid / water weight ratio = 0.5 to 2.0) is usually used. The amount of dilute hydrochloric acid used is 20 to 80% by weight with respect to concentrated sulfuric acid.

The detection solution containing carminic acid, hydrochloric acid and sulfuric acid is supported on a carrier and used as a detection agent for boron trichloride. The method of supporting on the carrier is not particularly limited, but for example, a supporting method such as an impregnation method can be adopted. The amount of the detection liquid carried on the carrier is generally 0.01 to 1.0, usually 0.1 to 0.5 in terms of the volume ratio of the detection liquid and the carrier.

In the present invention, the detection agent can further support copper sulfate, and by supporting copper sulfate, the coloration due to boron trichloride of the detection agent becomes clearer as compared with the case where copper sulfate is not supported. be able to. As a method of supporting copper sulfate, for example, after mixing and dissolving copper sulfate in the detection solution,
A method of supporting on a carrier can be adopted. The amount of copper sulfate used is preferably 0.01 to 1.0% by weight, more preferably 0.05 to 0.5% by weight, based on concentrated sulfuric acid.

As the carrier, it is preferable to use a carrier which is grayish white to white or transparent. A carrier having a low lightness such as carbon black cannot be used substantially because the change in the hue of the detection agent cannot be judged.
Examples of the carrier that can be used include α-alumina carrier, silica carrier, silica-alumina carrier and the like which are usually used as catalyst carriers. However, it goes without saying that the carrier needs to be substantially free of a boron compound.

The shape of the carrier is not particularly limited, and for example, spherical, granular (pellet), and crushed granular can be used.

The detection agent carried on the carrier as described above shows the color of the carrier itself or a pale blue color before contacting with boron trichloride.

When the detection agent of the present invention is brought into contact with boron trichloride, a complex is formed and the hue changes to pink. The detection agent of the present invention is
It is possible to detect 0.5 ppm or more of boron trichloride. Chlorine and chlorine compounds coexisting with boron trichloride, as well as other gases used for gas phase metal surface treatments such as dry etching, do not interfere with this reaction.

Furthermore, the detection agent of the present invention is extremely stable against halogen compounds such as chlorine, hydrogen chloride and halogenated hydrocarbons, and has a high sensitivity even when exposed to chlorine, hydrogen chloride and halogenated hydrocarbons for a long period of time. No decline was seen, and also
The colored complex is also stable to a halogen compound and does not discolor even when it is contacted with chlorine, hydrogen chloride or a halogenated hydrocarbon for a long time.

Next, a method for detecting breakthrough of boron trichloride in the boron trichloride adsorption device using the above-mentioned detecting agent will be described.

For example, when a waste gas obtained by dry etching using a gas obtained by diluting boron trichloride or carbon tetrachloride gas with nitrogen gas is introduced into a gas adsorption device filled with activated carbon as an adsorbent, these are initially removed. Other than the nitrogen gas, the gas is completely adsorbed and is not discharged from the gas discharge port. Further, as the adsorption proceeds, the adsorbent first breaks through hydrogen chloride generated by the decomposition of boron trichloride or chlorine gas, and hydrogen chloride gas flows out from the upper part of the adsorbent. However, in this state, the gas adsorption device has sufficient adsorption performance for boron trichloride. When the waste gas is further introduced, the gas adsorption device breaks through the boron trichloride, and the boron trichloride is discharged from the upper part of the adsorbent. When gas is further introduced, it breaks through carbon tetrachloride.

Boron chloride, water opposed immediately upon contact with (moisture contained in the air remaining in the piping, etc.) to produce a powdered B ₂ O ₃ as described above, the B ₂ O ₃ However, they are accumulated in the discharge port of the oil rotary pump and in the duct piping, which causes the blockage. Therefore, it is necessary to remove all the boron trichloride at an early stage. Since the gas discharged from the gas adsorption device is usually discharged after passing through other gas removing means such as an alkali scrubber, the gas (eg, hydrogen chloride gas) that can be removed by these gas removing means is trichloride. It is not necessary to completely remove boron with a gas adsorption device provided adjacent to the step of generating boron, and even if there is some outflow, it can be easily removed with an alkali scrubber or the like.

That is, if the breakthrough of boron trichloride in the gas adsorption device can be selectively detected, hydrogen chloride and the like flowing out before this breakthrough can be easily removed by an alkali scrubber, etc. Alternatively, the gas adsorbing device can be effectively used for a long period of time without trouble such as clogging of the pipe.

The method for detecting the breakthrough for boron trichloride in the boron trichloride adsorption device of the present invention is to selectively detect the breakthrough for boron trichloride in the gas containing boron trichloride based on such findings. Therefore, the gas adsorption device is intended to be effectively used for a long period of time.

Therefore, it is necessary to detect the breakthrough for boron trichloride directly, not for the breakthrough for hydrogen chloride etc. The detection agent used must be one that does not deteriorate with a gas other than boron trichloride, such as hydrogen chloride.

The method of detecting breakthrough of boron trichloride from the gas adsorption device of the present invention is, for example, gas adsorption in which a container 3 having a gas inlet 1 and a gas outlet 2 is filled with an adsorbent 4 as shown in FIG. A boron trichloride breakthrough detection unit 6 consisting of a container filled with the boron trichloride breakthrough detection agent 5 and having a see-through inside is installed in the vicinity of the gas outlet of the device. It can be carried out by checking the coloration.

The gas to be adsorbed in the present invention is a gas containing boron trichloride. Examples of components other than boron trichloride include:
Examples thereof include chlorinated hydrocarbons such as carbon tetrachloride and trichloroethylene, halogen gas such as chlorine gas, and hydrogen chloride gas. These gases may be diluted with an inert gas or the like.

The gas containing boron trichloride, which is the object of the present invention, is discharged as a waste gas during dry etching, for example.

Generally, dry etching uses boron trichloride, chlorine gas,
A gas obtained by diluting a gas component such as carbon halide with nitrogen gas is introduced into a dry etching apparatus to etch a metal to be processed, such as aluminum.

The adsorbent can be appropriately selected and used from commonly used adsorbents. Examples of adsorbents include activated carbon,
Activated alumina, silica gel, titanium dioxide, bentonite, acid clay, diatomaceous earth and calcium carbonate can be mentioned, and these can be used alone or in combination. A particularly preferred adsorbent is activated carbon. The adsorbent may be surface-treated according to a known technique or may be added with other components.

When the gas adsorber breaks through boron trichloride, the detection agent changes from grayish white or light blue to pink regardless of the presence of other coexisting gases. The breakthrough of the gas adsorption device with respect to boron trichloride can be selectively detected by detecting it with a measuring means or the like.

If the gas adsorbing device is replaced when the detection agent develops color, the adsorbing device can be replaced just before boron trichloride flows out of the gas adsorbing device, and the adsorbing device is in this state,
It adsorbs an amount of boron trichloride that approximately matches the adsorbable capacity. Therefore, the adsorption device is effectively used without waste.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 140 mg of carminic acid and 60 mg of copper sulfate pentahydrate to 4N
After adding to a mixed solution of 50 g of hydrochloric acid and 70 g of concentrated sulfuric acid and stirring and dissolving, 300 m of α-alumina carrier (average particle diameter 5 mm, manufactured by Fujimi Abrasives Co., Ltd., trade name: AM-S34)
Was added and stirred for 10 minutes to prepare a carrier-supported boron trichloride detection agent.

Example 2 Diameter 50 mm and length 255 having a dispersion plate with a diameter of 1 mm inside
A 500 mm Pyrex glass gas adsorber was filled with an adsorbent (granular activated carbon: about 3 mm diameter x 4 mm length) for 500 m, and the detection agent prepared in Example 1 was made of Pyrex glass near the gas outlet of the gas adsorber. A breakthrough detection unit for boron trichloride filled in the container was installed.

A boron trichloride-containing gas was introduced from the gas inlet of the gas adsorbing device to detect breakthrough of the device with respect to boron trichloride.

The boron trichloride-containing gas used was boron trichloride (BC ₃ ) diluted with nitrogen and chlorine gas. The flow rates of nitrogen, boron trichloride and chlorine gas are as follows.

Nitrogen 0.5 / min Boron trichloride 0.26 / min Chlorine gas 0.07 / min Chlorine hydrogen, chlorine and trichloride by sampling the exhaust gas near the gas outlet as needed while introducing the gas containing boron trichloride. The boron content was measured successively. The hydrogen chloride and chlorine were measured using a detector tube, and boron trichloride was absorbed in water and then measured by an absorptiometric method (curcumin method).

Although 50 ppm of hydrogen chloride was detected in the sample taken 85 minutes after the introduction of the gas containing boron trichloride, no change in hue was observed in the boron trichloride detection agent arranged. When the introduction was further continued, 16 ppm of boron trichloride was detected 122 minutes after the introduction. At this point, the boron trichloride detection agent turned pink from the gas adsorption device side. As a result of continuing the introduction, chlorine of 29 ppm was detected 140 minutes after the introduction and the introduction was continued for 240 minutes, but the pink color of the boron trichloride detection agent did not change.

That is, the boron trichloride detection agent can detect boron trichloride without being affected by the first outflowing hydrogen chloride, and the hue does not change even by chlorine gas flowing out after boron trichloride. .

The hydrogen chloride gas flowing out from the gas adsorption device could be completely removed by the alkali scrubber.

Example 3 5000 instead of the boron trichloride detection agent prepared in Example 1
The same operation was carried out except that a boron trichloride detection agent (prepared in the same manner as in Example 1) which had been allowed to stand for 1 month in nitrogen gas containing ppm hydrogen chloride gas and 1000 ppm chlorine gas was used. .

Also in the breakthrough test of the gas removing device using the boron trichloride detecting agent, the same result as in Example 2 could be obtained.
Therefore, it was confirmed that the boron trichloride detection agent was not affected by hydrogen chloride gas and chlorine gas.

EFFECTS OF THE INVENTION The detection agent of the present invention does not interfere with components contained in boron trichloride gas for dry etching, such as hydrogen chloride gas and chlorine gas, or gas components generated by the reaction of boron trichloride. Boron trichloride can be detected selectively. Furthermore, the degree of detection is high.

Further, by utilizing the method of the present invention, it is possible to selectively detect the breakthrough of the gas adsorbing device with respect to boron trichloride without being disturbed by other components. It can be used effectively, and it is possible to reliably grasp the adsorption state.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a gas adsorption device for a dry etching waste gas using a boron trichloride-containing gas and a boron trichloride breakthrough detection unit. First: gas inlet, 2: gas outlet, 3: container, 4: adsorbent, 5: boron trichloride breakthrough detection agent, 6: boron trichloride breakthrough detection unit

Claims (2)

[Claims] 1. A boron trichloride detection agent comprising carminic acid, hydrochloric acid and sulfuric acid supported on a carrier. 2. A detection agent for boron trichloride in which carminic acid, hydrochloric acid and sulfuric acid are carried on a carrier is filled near the gas outlet of a boron trichloride adsorption device filled with an adsorbent, and A breakthrough detection method for a boron trichloride adsorption device, which is characterized by detecting breakthrough by coloration.