JPH05296990A - Tape for detecting hydride gas - Google Patents

Abstract

PURPOSE:To detect a hydride gas through a color reaction without receiving any influence from the water content in the sample gas or environment. CONSTITUTION:The title tape is manufactured by impregnating a porous cellulose tape containing a gas absorbent, such as fine silica powder, etc., and humectant, such as glycerol, etc., with silver prochlorate and paratoluenesulfonic acid, with the former and latter respectively being used as a coloring agent and light resistance increasing agent. When the tape is exposed to a hydride gas contained in a sample gas, the silver prochlorate is reduced to colloidal silver by the hydride gas and reaction scars are produced. Since the amount of the colloidal silver is proportional to the concentration of the hydride gas, the concentration of the hydride gas can be found when the optical concentration of the reaction scars are measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detection tape most suitable for optically detecting from a reaction mark produced by reacting a hydride gas with a color former on a cellulosic tape.

[0002]

2. Description of the Related Art Metal hydrides such as silane (Si
Since H ₄ ), arsine (AsH ₃ ), phosphine (PH ₃ ), diborane (B ₂ H ₆ ) and the like are colorless and odorless gases, it is extremely difficult to detect them by the human five senses. Therefore, in the semiconductor industry handling these highly toxic gases, gas detectors sensitive to hydride gas are installed. Since the detection sensitivity of the electrochemical gas sensor and the semiconductor gas sensor for these hydride gases is extremely low, the reaction is usually caused by a color reaction with a reagent that causes an optical change by the reaction, and the concentration of the reaction mark generated at this time is measured by an optical density measuring device. Are measured and detected by.

As such a coloring agent, silver nitrate (AgN
O ₃ ) is well known. A hydride detection tape using silver nitrate supports silver nitrate on a breathable cellulosic tape and forms reaction traces of silver colloid when silver nitrate is reduced by exposure to hydride gas. Is configured. The concentration of the hydride can be easily known by measuring the optical concentration of the reaction mark. However, since silver nitrate has an extremely high photosensitivity, a hydride gas detection tape using silver nitrate usually needs to be stored in a light-shielded state, but still has a big problem that it turns brown in about 24 hours. ing. In order to solve such a problem, strong acid such as silver nitrate is added to cellulosic tape impregnated with silver nitrate or a hygroscopic agent to improve the light resistance by suppressing the generation of silver colloid by light as much as possible. The one that has been proposed is proposed (Japanese Patent Laid-Open No. 58-99753). The hydride detection tape to which silver nitrate is added can be stored for about half a year without causing discoloration if it is stored in a light-shielding container.

However, the nitric acid added to improve the light resistance nitrates the reagent carrier, cellulose, so that the mechanical strength of the tape sharply decreases over a long period of time. .. Such a problem becomes a serious problem when it is used in an automatic measuring device incorporating a gas sampling means and an optical concentration detecting means. In other words, in order to perform automatic measurement, the unused part of the gas detection tape must be exposed to the measurement area at regular intervals, so the normal detection tape is stored in the storage reel and is used during measurement. It is set on the measuring device in the other state by being passed over the winding reel via the route, and the unused portion is fed to the measuring area for a certain length at the stage when one gas sampling is completed. . Since a considerably large tension acts on the tape during this feeding, if the mechanical strength is reduced,
There is a problem that the measurement is interrupted due to disconnection.

In order to solve such a problem, the applicant of the present invention has previously proposed a method in which paratoluenesulfonic acid is used instead of nitric acid in order to improve light resistance (Japanese Patent Laid-Open Publication No. Hei 10 (1999) -242242).
2-275352). Since this tape does not undergo discoloration or nitration of cellulose for a long period of time, it has the characteristic that it can always maintain the same performance as during production and is extremely easy to use.

[0006]

However, since silver nitrate is used as the colorant, the measurement sensitivity is greatly affected by the sampling gas and the humidity of the environment, which causes a problem that the measurement result includes a large error. is there. The present invention has been made in view of such circumstances, and its object is to have excellent light resistance and mechanical strength, and moreover, have a constant detection sensitivity regardless of environmental humidity. It is to provide a tape for gas detection. A second object of the present invention is to provide a hydride detection tape capable of detecting silane in hydride gas, which has been conventionally difficult to detect by a color reaction.

[0007]

In order to solve such problems, in the present invention, a piece of porous cellulose paper containing a gas adsorbent and a humectant is used as a coloring agent of silver perchlorate. Further, paratoluenesulfonic acid was impregnated as a light resistance improver.

[0008]

The silver perchlorate supported on the tape reacts with the hydride gas and is reduced by an amount depending on the concentration of the gas to deposit colloidal silver to form reaction traces. Since the concentration of the reaction trace is proportional to the concentration of the hydride, the concentration of the hydride gas can be known by measuring its optical concentration.

[0009]

EXAMPLES The details of the present invention will be described below with reference to examples. Cellulose carrying a reagent - stearyl - flop sheet has air permeability carded vegetable fibers - shaping Doo body, silicic acid (H ₂ Si in those white as much as possible to bleach this
O ₃ ), magnesium oxide (MgO), aluminum oxide (A
It is formed by coating a gas adsorbent such as l ₂ O ₃ ) and then cutting it into a tape.

This gas adsorbent carries a gas, a liquid and a dissolved substance, and adsorbs moisture and hydride gas necessary for the reaction to promote the reaction with silver perchlorate on the tape. Acts to cause. The cellulose tape is impregnated with 1.3 to 2.5 g of silver perchlorate, 1 to 3 g of paratoluenesulfonic acid, and 25 g of glycerin per 1 square meter of rice.

As a method of supporting these reagents on the cellulosic tape, an organic solvent such as methanol is added with silver perchlorate at a concentration of 0.5 to 2.0 w / v percent and paratoluenesulfonic acid. 1 w / v percent, glycerin 1
The above-described cellulosic tape is dipped in a preparation solution obtained by dissolving 5v percent, and the solution is impregnated into the cellulosic solution. Then, the tape can be pulled out from the preparation liquid and the organic solvent contained in the tape can be evaporated at room temperature to leave only the reagent in the tape.

FIG. 2 shows an example of an apparatus for measuring the gas concentration using a gas detection tape. In the drawing, reference numeral 1 is arranged so as to face the conveyance path of the tape 2. A through hole 3 having a diameter of about 1 cm is formed on the surface of the gas suction portion facing the tape 2 and a negative pressure from a suction pump (not shown) acts via the pipe 4. Is configured.

Reference numeral 5 is a measuring head portion 5 arranged on the other surface side of the tape 2 facing the through hole 3 of the gas suction portion 1, and the through hole is formed at a position facing the through hole of the suction portion 1. The light-emitting element 7 and the light-receiving element 8 are formed inside the light-shielding container.
Are arranged and housed in such a relationship that a reaction mark formed on the tape 2 can be detected, and an inlet 9 for the test gas is provided at one end. The gas detection table described above
When the tape is set on the reels 10 and 11 and suction pressure from a pump (not shown) is applied to the suction portion 4, the test gas is sucked into the measurement head portion 5 from the inlet 9. The gas to be detected passes from the through hole 6 to the through hole 3 via the detection tape 2.
Is discharged from the outside. During the process in which the test gas passes through the detection tape 2, silver perchlorate on the tape 2 selectively reacts with arsine, which is a hydride, and colloidal silver corresponding to the concentration of arsine is produced. Precipitates on the surface.

In this way, the predetermined sampling time,
For example, when about 20 seconds have passed, the suction is stopped and the process for measuring the optical density of the reaction trace is started. The light from the light emitting element 7 is absorbed according to the optical density of the reaction mark formed on the tape surface, so that the optical density before the start of measurement, that is, the optical density with the background of the tape is measured. By obtaining the difference in concentration, it is possible to know the concentration or integrated amount of the hydride gas that has passed through the tape. At the time when the measurement for one sampling is completed, the winding reel 10 is driven and released.
The unused portion of the tape housed in the tool 11 is moved to the measurement area.

FIG. 3 shows the results of measuring the change in the optical density while changing the concentration of arsine using the above-mentioned measuring device, and the symbols (A) and (B) in the figure show the above. The hydride gas detection tape of the present invention, and the symbol (C) in the figure, shows the measurement results of a conventional hydride gas detection tape using silver nitrate as a coloring agent. According to the gas detection tape of No. 1, not only the detection output shows extremely high linearity with respect to the concentration of arsine, but also it has higher sensitivity than the conventional hydride gas detection tape using silver nitrate. It turned out that

Further, the above gas detecting tape is placed at a position 30 cm directly under a 20 watt fluorescent lamp, and an accelerated light resistance test is carried out by measuring the time until the discoloration can be visually confirmed. As a result, discoloration that could be visually recognized occurred in about 20 hours. On the other hand, when the light resistance of the conventional tape for detecting a hydride gas described in JP-A-58-99753 was examined by the same method, it was discolored in about 6 hours. As a result, it was found that the gas detection tape of the present invention has not only superior measurement sensitivity to the conventional hydride gas detection tape, but also about three times higher light resistance.

Further, a humidifying means is connected in the middle of the sampling tube to keep the concentration of the hydride gas to be detected constant, and only the humidity is changed from 5% relative humidity, which is called dry gas, to almost saturated state. When the change in the detection output was investigated while changing it, a substantially constant detection output was obtained irrespective of the humidity as shown by the symbol (A) in FIG.

On the other hand, when a similar investigation was conducted using a conventional hydride detection tape using silver nitrate as a color developing agent, as shown by the reference numeral (B) in FIG. It was found that the detection output rises with humidity, and the detection sensitivity greatly depends on the humidity. A similar investigation was conducted using the hydride detection tape disclosed in Japanese Patent Laid-Open No. 2-275352, which has a relatively small humidity dependency. As indicated by the symbol (C), the change in sensitivity was not negligible in practical use.

Example 1 Silver perchlorate 2 to 4 g w / v percent, paratoluene sulfonic acid 1 to 5 w
/ V% and further glycerin 25 v / v% were dissolved in methanol respectively, and the cellulosic tape coated with the gas adsorbent was dipped in the prepared solution, and then pulled up to tape. The methanol contained is evaporated at room temperature. By such a method, a tape containing 1.3 to 2.6 g of silver perchlorate, 0.6 to 3 g of paratoluenesulfonic acid, and 25 g of glycerin per square meter can be obtained. When phosphine (PH ₃ ) was detected using this detection tape, it could be detected with high linearity as shown in FIG.
Further, when the influence of the concentration of silver perchlorate on the detection sensitivity was examined, as shown in FIG. 5, practical detection sensitivity could be obtained if the concentration was 0.5 g or more per square meter. 1
Any concentration of about 4 grams / square rice to 4 grams / square rice can be supported. It should be noted that if the amount is 4 g / square meter or more, the gas can be detected for the time being, but not only the detection sensitivity is lowered, but also the amount of the color developing agent is increased, which is not a good measure for economic reasons. ..

[Example 2] Silver perchlorate 2 to 4 w / v percent, paratoluenesulfonic acid 1 to 5 w / v percent
In addition to Cent and glycerin 25 to 26 v / v percent, ethylene glycol 1 to 15 w / v percent, which is a divalent alcohol, was dissolved in 100 ml of an organic solvent such as methanol. The solution is used for cellulosic silver perchlorate 1.3 to 2.6 g / square rice, paratoluenesulfonic acid 0.6 to 3 g / square rice, glycerin 25 g / square meter and ethylene. A detection tape carrying 1 to 15 grams / square rice of glycol was prepared. Also in the tape for detecting hydride according to this embodiment, not only the sensitivity to humidity, the mechanical strength and the light resistance are excellent, but also ethylene glycol is a hydride gas, as in the first embodiment. It has a great feature that it enhances the detection sensitivity to all kinds of hydride gases in order to accelerate the reaction between chlorination and silver perchlorate. Especially silane (S
For iH ₄ ), as shown in FIGS. 6A and 6B, a hydride gas detection table using silver nitrate as an indicator.
The detection sensitivity is about 3 to 4 times higher than that of the detection output (C). The detection tape shown in the first embodiment containing no ethylene glycol was 100
It only showed the output to other hydride gases for the silane gas of about twice as high concentration. From this, the tape for hydride detection according to the present invention can be applied to the detection of hydride gas used in the semiconductor industry,
The hydride gas can be monitored with high reliability.

In the above-mentioned embodiments, the examples in the hydride gas are arsine, diborane, phosphine and silane. However, disilane (Si ₂ H ₆ ), hydrogen selenide (SeH ₂ ) and germane ( GeH ₄ ), hydrogen sulfide (H ₂
It was confirmed that the detection sensitivity was provided for the detection of other hydride gases such as S).

[0022]

As described above, according to the present invention,
Since a porous tape-shaped carrier containing a gas adsorbent and a humectant was impregnated with silver perchlorate as a coloring agent and parasulfonic acid as a light resistance improver, the water content in the test gas was increased. The detection sensitivity can be prevented from fluctuating and the hydride gas can be detected with a constant sensitivity regardless of the sampling gas and the humidity of the surrounding environment, and the light resistance during storage is improved without the need for a strong acid. Therefore, it is possible to prevent a decrease in mechanical strength due to nitration of the tape. As a result, the performance at the time of manufacture can be exhibited even after long-term storage.

In the second aspect of the invention, since ethylene glycol is added to silver perchlorate and parasulfonic acid, ethylene glycol accelerates the reaction between silver perchlorate and hydride gas. By the way, it is possible to detect the hydride gas with higher sensitivity by preventing the fluctuation of the detection sensitivity to humidity, and in particular, to add silane, which has been difficult to detect by the color reaction, to the detection target. It is possible to detect almost all kinds of hydride gases with the same device.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in hydride gas detection sensitivity with respect to humidity, in which (A) shows the sensitivity change of a hydride detection tape according to the present invention, and (B) and (C) in the figure. Shows a change in sensitivity of a conventional tape for detecting a hydride gas, which uses silver nitrate as a coloring agent.

FIG. 2 is a diagram showing the principle of a gas detector using the tape for detecting a hydride gas of the present invention.

3 (A) and 3 (B) are diagrams showing the relationship between the concentration of arsine and the detection output by the tape for detecting a hydride gas of the present invention, and FIG. 3 (C) is a silver nitrate. FIG. 7 is a diagram showing the detection output of arsine by a conventional tape for detecting a hydride gas, in which is used as a coloring agent.

4 (A) and (B) are diagrams showing the relationship between the concentration of phosphine and the detection output by the tape for hydride detection of the present invention, and FIG. 4 (C) is silver nitrate. FIG. 7 is a diagram showing the detection output of phosphine by a conventional tape for hydride detection in which is used as a coloring agent.

FIG. 5 is a diagram showing the relationship between the concentration of silver perchlorate and the detection output.

6 (A) and 6 (B) are detection outputs of silane when ethylene glycol was added to the tape for detecting hydride gas of the first embodiment, and FIG. 6 (C). FIG. 3 is a diagram showing the detection output of silane by a conventional hydride detection tape using silver nitrate as a coloring agent.

Claims (2)

[Claims] 1. A hydride gas obtained by impregnating a breathable cellulose paper piece containing a gas adsorbent and a moisturizing agent with silver perchlorate as a coloring agent and paratoluenesulfonic acid as a light resistance improving agent. Detection tape. 2. An air-permeable cellulose paper piece containing a gas adsorbent and a humectant, silver perchlorate as a coloring agent, paratoluenesulfonic acid as a light resistance improver, and ethylene glycol. Hydride gas detection tape impregnated with a sensitizer.