JPH0554627B2 - - Google Patents

Description

[Detailed description of the invention] [Field of invention] The present invention relates to a boron trichloride adsorption device.

[Background of the Invention] In recent years, precision electronic components such as LSIs are increasingly manufactured by dry etching aluminum or the like. Recently, boron trichloride has been used as a dry etching gas, either alone or in combination with boron trichloride and other components such as boron tetrachloride, halogenated hydrocarbons such as carbon tetrafluoride, or halogen gases such as chlorine gas. A mixture of gases is used.

Since the above gases cause environmental pollution, their release into the atmosphere is strictly regulated. In particular, boron trichloride, in addition to the environmental problems mentioned above, produces B ₂ O ₃ powder when it comes into contact with air, etc., and this powder can accumulate and cause blockages in oil rotary pump discharge ports and duct piping. There is. Therefore, apart from environmental concerns, it is necessary to ensure that boron trichloride in particular is removed before it forms B ₂ O ₃ powder.

Generally, in the case of dry etching, the object to be treated is dry etched by continuously contacting boron trichloride or a gas containing boron trichloride, and then the waste gas discharged from the dry etching equipment is treated with activated carbon, etc. A method is used in which gas components to be adsorbed are 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 alkaline scrubber or the like.

A gas adsorption device filled with such an adsorbent is
When the adsorbent adsorbs a certain amount of substance, it will break through, and if more gas to be adsorbed flows into the gas device that has broken through, the gas to be adsorbed will no longer be sufficiently adsorbed by the adsorbent. The gas will flow out from the gas outlet.

Normally, when adsorption is carried out by flowing waste gas after dry etching using a gas containing chlorine gas and boron trichloride into an adsorption device such as the one described above, the gas adsorption device absorbs boron trichloride. Breakthrough occurs for hydrogen chloride gas contained in boron-containing waste gas, and then for boron trichloride.

Conventionally, a method for detecting breakthrough in a gas adsorption device is to apply acidic gas (a gas that becomes acidic when dissolved in water) to the adsorbent near the gas outlet of the gas adsorption device.
A method is used in which a detection agent (indicator) is attached and breakthrough is detected by a change in the hue of the indicator.

This detection agent is sensitive to hydrogen chloride, so in dry etching using a gas containing boron trichloride, the breakthrough of the gas adsorption device is detected when the gas adsorption device breaks through to hydrogen chloride gas. At this point, the adsorption device had sufficient adsorption performance for boron trichloride.

Hydrogen chloride gas, etc. that flows out from the gas adsorption device before the breakthrough of boron trichloride can be easily removed using an alkaline scrubber attached to a normal gas adsorption device. If the breakthrough of the device to boron trichloride can be selectively detected, the gas adsorption device can be used effectively for a longer period of time.

Based on this idea, the present inventor developed a detection agent that selectively detects boron trichloride without being sensitive to gases that break through earlier than boron trichloride, such as hydrogen chloride gas, and this detection agent. He has invented an invention relating to a method for detecting breakthrough in a gas adsorption device using the method, and has already filed an application (Japanese Patent Application No. 35065/1983).

This invention relates to a detection agent in which 1,1'-dianthrimide and sulfuric acid are supported on a carrier as a selective detection agent for boron trichloride, and a method for detecting breakthrough in a gas adsorption device using this detection agent. By implementing the present invention, it is possible to selectively detect the breakthrough of boron trichloride in the adsorption device and use the adsorption device effectively.

However, most of the adsorbents filled in gas adsorption equipment have already adsorbed moisture before use.
As the adsorbent adsorbs target gases, such moisture replaces these gases and is discharged from the top of the adsorbent and enters the detection section where it selectively detects boron trichloride. It has been found that the sensitivity of detection agents containing 1,1'-dianthrimide and sulfuric acid tends to be reduced.

In order to prevent the sensitivity of the detection agent from decreasing, the adsorbent can be dried before use to remove the moisture adsorbed on the adsorbent, but this method requires drying a large amount of the adsorbent. However, the adsorbent becomes extremely expensive and cannot be used in practice. It is also possible to use an adsorbent that does not adsorb moisture, but in reality commercially available adsorbents that do not adsorb moisture are very expensive.
It cannot be used as an adsorbent in boron trichloride adsorption equipment.

[Object of the Invention] The present invention is a gas adsorption device capable of adsorbing and removing boron trichloride, and is capable of effectively detecting the breakthrough of boron trichloride without being hindered by moisture. The purpose is to provide an adsorption device.

[Summary of the Invention] The present invention provides a boron trichloride adsorption unit in which an adsorbent is filled inside a container having a gas inlet and a gas outlet, and a boron trichloride adsorption unit in the vicinity of a gas outlet of the adsorption unit. A boron trichloride adsorption device is equipped with a boron trichloride detection section in series with the boron trichloride detection section, and the detection agent filled in the boron trichloride detection section contains 1,1'-dianthrimide and sulfuric acid. and a water adsorption section made of synthetic zeolite having a molecular sieving action is provided between the adsorbent and the detection section.

[Effects of the Invention] The boron trichloride adsorption device of the present invention allows the gas adsorption device to absorb boron trichloride without any effect on the detection agent even if the adsorbent contains moisture. Breakthrough can be detected.

Furthermore, by using the boron trichloride adsorption device of the present invention, it is possible to selectively detect the breakthrough of boron trichloride in the gas adsorption device without being interfered with by other components such as moisture. The device can be effectively used for a substantially long period of time, and the adsorption state can be reliably grasped.

[Detailed Description of the Invention] Hereinafter, the boron trichloride adsorption device of the present invention will be described with reference to the attached drawings.

FIG. 1 is a diagram schematically showing an example of the arrangement of each device when the boron trichloride adsorption device of the present invention is brought into contact with a gas generation device and a gas removal means.

The boron trichloride adsorption device of the present invention basically consists of a boron trichloride adsorption unit 4 in which an adsorbent 3 is filled inside a container having a gas inlet 1 and a gas outlet 2; This boron trichloride adsorption device is equipped with a boron trichloride detection section 5 provided in series with this boron trichloride adsorption section 4 in close proximity to the gas outlet 2 of the boron trichloride adsorption device.

Then, between the adsorbent 3 and the boron trichloride adsorption section 5, the gas introduced into the boron trichloride adsorption section 2 from the gas introduction port 1 selectively captures moisture in the gas that has passed through the adsorption agent 3. A water adsorption section 6 made of synthetic zeolite having molecular sieving action is provided.

The adsorbent 3 filled in the gas adsorption section 4 can be appropriately selected 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 mixtures. A particularly preferred adsorbent is activated carbon. Note that the above-mentioned adsorbent may be surface-treated according to a known technique, or may have other components added thereto. Usually, such adsorbents already have moisture adsorbed before use.

The gas adsorption section 4 has a gas inlet 1 and a gas outlet 2.
If the adsorbent 3 is filled inside and the water adsorption part 6 made of synthetic zeolite with molecular sieving action is provided between the adsorbent 3 and the boron trichloride adsorption part 5, the shape, capacity, etc. There are no particular restrictions.
An example of the shape is an adsorption tower type.

The detection section 5 is filled with a detection agent consisting of 1,1'-dianthrimide and sulfuric acid that is sensitive to boron trichloride. And this detection agent is
It has the property of turning blue in the presence of boron trichloride, but turns pink in the presence of water.
Such a detection agent usually has 1,1'-dianthrimide and sulfuric acid supported on a carrier.

Concentrated sulfuric acid is usually used as the sulfuric acid of the above-mentioned detection agent. The combination of concentrated sulfuric acid and 1,1'-dianthrimide may be in a state in which 1,1'-dianthrimide is dissolved in concentrated sulfuric acid, or in a state in which a small amount of concentrated sulfuric acid is added to 1,1'-dianthrimide. However, 1,1'-dianthrimide can generally be used by dissolving it in concentrated sulfuric acid. Generally, 0.05 to 2.0% by weight of 1,1'-dianthrimide is dissolved in concentrated sulfuric acid and used. 1,1'-dianthrimide is a dark red needle-shaped crystal, but when dissolved in concentrated sulfuric acid, the solution takes on a green to pale green color.

Such a detection agent is usually used for detecting boron trichloride while supported on a carrier. As the carrier, it is preferable to use a carrier which itself is grayish-white to white or transparent. A carrier with low brightness such as carbon black cannot be practically used because it is not possible to judge the change in hue of the detection agent. Examples of supports that can be used include those commonly used as catalyst supports, such as α-alumina supports, silica supports, and silica-alumina supports. However, it goes without saying that the carrier needs to be substantially free of boron compounds.

There is no particular restriction on the shape of the carrier, for example, spherical,
Granules (pellets) and crushed granules can be used.

The detection agent supported on the carrier as described above exhibits the color of the carrier itself or a light green color before contact with boron trichloride.

When the above detection agent comes into contact with boron trichloride, a complex is formed and the hue changes to blue. Such a detection agent can detect 0.5 ppm or more of boron trichloride. Chlorine and chlorine compounds coexisting with boron trichloride, as well as other gases used in 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 low sensitivity even when exposed to chlorine, hydrogen chloride, and halogenated hydrocarbons for long periods of time. No deterioration was observed, and the colored complex was also stable against halogen compounds, such as not changing color even after prolonged contact with chlorine, hydrogen chloride, or halogenated hydrocarbons.

However, the above-mentioned detection agent reacts with water, turns pink, and its ability to detect boron trichloride is reduced.

As mentioned above, the adsorbent usually contains some moisture, and as the adsorbent adsorbs the gas, the contained moisture replaces the adsorbed gas and is discharged from the upper part of the adsorbent.

Therefore, by preventing the water discharged from the upper part of the adsorbent from entering the detection part, the ability to detect boron trichloride is maintained.

In FIG. 1, reference numeral 6 denotes a water adsorption section made of synthetic zeolite that captures the water discharged from the above-mentioned adsorption upper part so as not to be introduced into the detection section 5. This synthetic zeolite has molecular sieve action. Synthetic zeolites that have a molecular sieve action that traps moisture (or may trap boron trichloride) without trapping hydrogen chloride etc. generally have a particle size within the range of 2 to 10 Å (preferably 2 to 9 Å). It is known as a molecular sieve with pore size. Synthetic zeolite has high selectivity for capturing moisture in gases due to its high polarity, and can effectively remove moisture.

Note that the above-mentioned adsorbent such as activated carbon has a larger pore size than synthetic zeolite, so it does not have a molecular sieving action.

There is no particular restriction on the method of attaching the synthetic zeolite as long as it is capable of trapping the moisture discharged from the upper part of the adsorbent 3 as described above.

Generally, the adsorbent is arranged in a layered manner on the adsorbent 3 so that the gas that has passed through the adsorbent 3 passes through a layer composed of entirely synthetic zeolite.

When the water adsorbent is layered, the amount of synthetic zeolite and adsorbent is preferably within the range of 1:2 to 1:10 in terms of weight ratio, and the cross-sectional area of the adsorption part is usually in the upper and lower parts. Since these are the same, the ratio of the thicknesses of the layer made of synthetic zeolite and the layer made of adsorbent is usually within the range of 1:2 to 1:10.

In addition, a filling device (not shown) is arranged in series with the gas adsorption section 2 between the gas exhaust port 2 and the detection section, and the gas discharged from the gas discharge port 3 passes through the filling device and reaches the detection section 5. It is also possible to provide it so that it can be introduced.

Such a boron trichloride adsorption device is normally used as follows.

The boron trichloride adsorption unit 4 is normally connected to the gas generator 7 at the gas inlet 1. A detection section 5 is connected to the gas discharge port 2 of the boron trichloride adsorption section 4, and the detection section 5 is connected to the gas removal means 8.

The gas generated by the gas generator 7 is transferred to the gas inlet 1
is introduced into the interior of the boron trichloride adsorption section 2.

The gas generating device 7 is, for example, a dry etching device. The gas discharged as waste gas from the gas generator is a gas containing boron trichloride. Examples of components other than boron trichloride include chlorinated hydrocarbons such as carbon tetrachloride and trichlorethylene, halogen gases such as chlorine gas, and hydrogen chloride gas, and these gases are usually inert gases. It is diluted with etc.

Note that the process for generating the gas containing boron trichloride is not limited to the dry etching process, and may be any other process that generates the gas containing boron trichloride. Therefore, the above-mentioned boron trichloride-containing gas may be diluted with other gases used in the generation process, or may be a mixed gas with other gases.

A gas containing boron trichloride discharged from the gas generating device (dry etching device) 7 is introduced into the boron trichloride adsorption section 4 .

Boron trichloride, hydrogen chloride, and hydrogen chloride contained in the boron trichloride-containing gas introduced into the boron trichloride adsorption section
Gases such as chlorine are adsorbed and removed by the adsorbent, and other diluting gases and moisture contained in the adsorbent are discharged from the upper part of the adsorbent 3, which has a molecular sieve action placed above the adsorbent 3. It passes through a layer of synthetic zeolite. Moisture is completely captured in this layer and does not enter the detection section 5.

A boron trichloride detection section 5 is provided near the gas outlet 2 of the boron trichloride adsorption section 4 . The detection part 5 is filled with a detection agent of boron trichloride. The detection part is usually connected to the gas outlet with a coupler or the like.

The breakthrough of the boron trichloride-containing gas through the boron trichloride adsorption unit does not occur simultaneously for all contained gases as described above, but specifically for each gas.

Gases such as hydrogen chloride gas which reach breakthrough before the breakthrough of boron trichloride and flow out from the boron trichloride adsorption section are easily removed by other gas removal means 8 such as an alkaline scrubber.

When the boron trichloride adsorbing part breaks through to boron trichloride, the detection agent changes from grayish white to pale green to blue, so this change in hue can be detected with the naked eye or by optical measuring means. Breakthrough of boron trichloride in the boron adsorption part can be selectively detected.

When the detection agent develops color, replace the boron trichloride adsorption device consisting of the boron trichloride adsorption section and the detection section.

Next, Examples and Comparative Examples of the present invention will be shown.

Example 1 450 mm long with a gas inlet and a gas outlet,
Activated carbon (shape: columnar, average short axis length: 4 mm, average long axis length: 5 mm, manufactured by Kuraray Chemical Co., Ltd., product name:
4GS) 50Kg was filled. The moisture content of this activated carbon is 3.0% by weight.

Synthetic zeolite (pore size:
9 Å, average particle diameter: 3 mm, 10 kg of spherical synthetic zeolite (manufactured by Awata Kogyo Co., Ltd., trade name: WE-894) was filled to form a layer of synthetic zeolite.

0.7 g of 1,1'-dianthrimide was dissolved in 200 g of concentrated sulfuric acid, and 467 g of α-Al ₂ O ₃ carrier (average particle size 5 mm, manufactured by Fujimi Abrasives Co., Ltd., product name: AM-) was dissolved in 200 g of concentrated sulfuric acid.
A boron trichloride detection agent was prepared by adding S34) and adsorbing a concentrated sulfuric acid solution of 1,1'-dianthrimide onto the carrier.

The detection unit 5 containing the boron trichloride detection agent in a glass container was placed at the gas outlet 1 of the boron trichloride adsorption unit 4 via a connecting pipe as shown in FIG.

The connecting pipe between the boron trichloride adsorption section 4 and the detection section 5 filled with a detection agent is provided with a sampling hole for collecting a sample for analyzing the gas discharged from the boron trichloride adsorption section 4. There is.

A boron trichloride-containing gas was introduced from the gas inlet 1 of the boron trichloride adsorption section 4, and the breakthrough of the boron trichloride in this adsorption section was detected.

As the boron trichloride-containing gas, boron trichloride (BCl ₃ ) diluted with nitrogen and chlorine gas were used.
Note that the flow rates of nitrogen gas, boron trichloride, and chlorine gas are as follows.

Nitrogen gas 10/min Boron trichloride 0.15/min Chlorine gas 0.05/min While introducing the boron trichloride-containing gas, gas was collected from the above sampling hole and the contents of hydrogen chloride, chlorine, and boron trichloride were sequentially measured. . Note that hydrogen chloride and chlorine were measured using a detection tube, and boron trichloride was absorbed by water and then measured by spectrophotometry (curcumin method).

Although 45 ppm of hydrogen chloride was detected in a sample taken 84 hours after the introduction of the boron trichloride-containing gas, no change in hue was observed. When the introduction was continued, 1.3 ppm of boron trichloride was detected for the first time 354 hours after introduction. At this point, the boron trichloride detection agent changed from white to dark blue.

Hydrogen chloride gas flowing out from the boron trichloride adsorption unit could be completely removed using an alkaline scrubber.

Comparative Example 1 Boron trichloride was adsorbed and removed in the same manner as in Example 1, except that the synthetic zeolite was not filled on the activated carbon.

Two hours after introducing the boron trichloride-containing gas, the boron trichloride detection agent changed from white to pink due to adsorption of water. As a result of further introduction, 1.0 ppm of boron trichloride was detected 347 hours after introduction, but the hue of the boron trichloride detection agent remained pink, and no change in hue could be confirmed.

The boron trichloride adsorption part (Example 1) of the present invention is
Moisture in the gas that has passed through the adsorbent is captured by the water adsorption part made of synthetic zeolite, and the boron trichloride detection agent does not lose its effectiveness as a detection agent for boron trichloride. Breakthrough of boron trichloride in the adsorption part can be reliably detected.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an example of the arrangement of each device when the boron trichloride adsorption device of the present invention is connected to a gas generation device and a gas removal means. 1: gas inlet, 2: gas outlet, 3: adsorbent, 4: boron trichloride adsorption section, 5: detection section (boron trichloride detection section), 6: water adsorption section, 8: gas removal means.

Claims (1)

[Scope of Claims] 1. A boron trichloride adsorption unit, in which an adsorbent is filled inside a container having a gas inlet and a gas outlet, is provided with a boron trichloride adsorption unit adjacent to a gas outlet of the adsorption unit. A boron trichloride adsorption device equipped with a boron trichloride detection section in series, wherein a detection agent filled in the boron trichloride detection section contains 1,1'-dianthrimide and sulfuric acid, and A boron trichloride adsorption device characterized in that a water adsorption section made of synthetic zeolite having a molecular sieving action is provided between the adsorbent and the detection section. 2. The boron trichloride adsorption device according to claim 1, wherein the synthetic zeolite is arranged in a layered manner on the adsorbent. 3. The boron trichloride adsorption device according to claim 1 or 2, wherein the adsorbent is activated carbon. 4. The boron trichloride adsorption device according to claim 1 or 2, wherein the gas introduced into the boron trichloride adsorption device is waste gas from a dry etching process.