JPH0618510A - Tape for detecting hydride gas - Google Patents

Abstract

PURPOSE:To detect a hydride gas having a low light fastness without deteriorating the mechanical strength of a carrier by impregnating a piece of porous cellulose paper carrying a gas adsorbent and humectant with silver p- toluenesulfonate as a coloring agent and p-toluenesulfonic acid as a light-fastness improver. CONSTITUTION:A cellulose tape carrying a gas adsorbent and humectant is impregnated with silver p-toluenesulfonate, p-toluenesulfonic acid, and glycerin at rates of >=0.3g/m<2>, 0.3-3.0g/m<2>, and about 25g/m<2>, respectively. Since the detection output of this tape corresponds to the concentration of a hydride gas with an extremely high linearity, the sensitivity of the tape against the hydride gas is extremely high. In addition, since the tape is impregnated with p-toluenesulfonic acid, the light fastness of the tape is high and the tape can be used especially for highly accurately measuring low-concentration sample gases and silane gases which are low in reaction against coloring agents Moreover, since the tensile strength of the tape is 0.55km/mm<2>, the tape can be mounted on an automatic measuring instrument with high reliability.

Description

Detailed Description of the Invention

[0001]

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

[0002]

BACKGROUND OF THE INVENTION Metal hydrides such as phosphine (P
Since H ₃ ), silane (SiH ₄ ), arsine (AsH ₃ ), diborane (B ₂ H ₆ ) and the like are colorless and odorless gases, detection by the human five senses is extremely difficult. Therefore, in the semiconductor industry handling these highly toxic gases, gas detectors sensitive to hydride gas are installed. Since the detection sensitivity of electrochemical gas sensors and semiconductor gas sensors for these hydride gases is extremely low, a color reaction is usually made 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. By measuring the optical density of this reaction mark, the concentration of hydride can be easily known. 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, since nitric acid added to improve light resistance is a strong acid, it nitrates the reagent carrier, cellulose, so that the mechanical strength of the tape is prolonged. The strength drops sharply. 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 at the time of this feeding, there is a problem that if the mechanical strength is lowered, the tape is cut and the measurement is interrupted.

In order to solve such a problem, the present applicant previously used paratoluenesulfonic acid in place of nitric acid in order to improve the light resistance without lowering the mechanical strength of the reagent carrier. Proposed one (Japanese Patent Laid-Open No. 2-275352
Issue). Since this tape does not undergo discoloration or nitration of cellulose for a long period of time, it has the characteristic that it maintains the same performance as at the time of manufacture and is extremely easy to use.

[0006]

However, due to the fact that silver nitrate is used as a coloring agent, the photosensitivity of silver nitrate cannot be neglected and a slight discoloration occurs in those stored for a long period of time. There is a problem that the measurement error cannot be ignored especially in the measurement of gas with low detection sensitivity. The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydrogenated gas detection tape which does not decrease the mechanical strength of a reagent carrier and has almost no photosensitivity. Is to provide.

[0007]

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

[0008]

[Function] The silver paratoluenesulfonate supported on the tape reacts with the hydride gas in spite of its extremely low photosensitivity as compared with silver nitrate, and the amount depending on the gas concentration is increased. It is reduced only and colloidal silver is deposited 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 the optical concentration of this.

[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.

The gas adsorbent impregnated in the cellulo-step carries a gas, a liquid and a dissolved substance, and always retains the water necessary for the reaction between the hydride gas and the color developing agent. At the time of detection, it serves to adsorb a hydride gas and accelerate the reaction with silver p-toluenesulfonate on the tape. The cellulos configured in this way
On a step, 0.3 g or more of silver p-toluenesulfonate, 0.3 to 3.0 g of p-toluenesulfonic acid and about 25 g of glycerin are impregnated and supported per 1 square meter of rice.

As a method of supporting these reagents on the cellulosic tape, silver paratoluenesulfonate is added to an organic solvent such as methanol at a concentration of 0.5 to 2.0 w / v percent and paratoluenesulfone. 0.5 to 4.5 w / acid
The above-mentioned cellulo-step is dipped in a preparation solution prepared by dissolving 15% v-cent and glycerin,
It is impregnated into the cellulose together with the solvent. Then, the tape is pulled out from the preparation liquid, and the organic solvent is evaporated at room temperature to allow silver p-toluenesulfonate, p-toluenesulfonic acid, and glycerin to remain in the tape. By repeating such an operation once or a plurality of times depending on the concentration of the reagent contained in the preparation liquid, the reagent having a predetermined concentration can be supported on 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 p-toluenesulfonate on the tape 2 selectively reacts with a hydride, for example, phosphine (PH ₃ ), and an amount proportional to the concentration of phosphine. Colloidal silver
Deposits on the surface of the wafer.

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. 2 is a calibration chart in which the detection output by the tape for detecting a hydride gas of the present invention was examined by changing the concentration of phosphine, which is a typical example of a hydride gas, using the above measuring apparatus. It is a line, and it is clear that the detector output and the gas concentration correspond with a very high linearity. The sensitivity to gas was comparable to that of a conventional tape for detecting hydride gas, which uses silver nitrate as a coloring agent.

The above-mentioned gas detection tape is placed 20 cm directly under a 20 watt fluorescent lamp and irradiated with light close to natural light (illuminance of about 1500 lux) to detect the gas detection tape. When the change in concentration was measured, the results shown in the figure were obtained. That is, the optical density of the hydride detection tape at the time of non-exposure is set to the reference value D0, and the ratio (Dt) between the difference (Dt-D0) from the density Dt of the same tape in a predetermined time and the reference density. -D0) / D0 is measured. As is clear from FIG. 3, the hydride gas detection tape of the present invention (A in the figure) uses conventional silver nitrate as a color developing agent,
Compared to a tape that uses nitric acid as a light-proofing agent (B in the figure) and a tape that uses paratoluene sulfonic acid instead of nitric acid to improve mechanical strength (C in the figure). It can be seen that the density change rate with respect to the exposure time is as small as 1/4 to 1/3 particularly in the initial stage (total exposure time of about 10 hours). Considering that in the normal storage state, the exposure for about 10 hours in the above-mentioned test is hardly received, the hydride gas detection tape of the present invention is practically practically optical if stored normally. There is no change in concentration. In fact, no noticeable discoloration occurred even when left in the room as it was. As described above, the high light resistance of the hydride gas detection tape according to the present invention means that the sample gas having a particularly low concentration and the silane gas having a low reactivity with the color developing agent can be measured with high accuracy.

Next, in order to investigate the strength of the tape for detecting a hydride gas of the present invention, the tensile strength was measured by using a paper sheet tester manufactured by Instron Co., and it was 0.55 kg per square millimeter. On the other hand, the conventional tape for detecting a hydride gas using nitric acid as the light resistance improver was 0.4 kg / square millimeter, which is about 70 percent of the present invention. From this, it was found that the device of the present invention can perform automatic measurement with high reliability even when mounted on an automatic measuring device.

[Example] Silver p-toluenesulfonate is 0.5 w / v percent or more (of course, silver p-toluenesulfonate has a very low solubility, so it is saturated at about 4 w / v percent at room temperature). , Para-toluenesulfonic acid 0.5 to 4.5 w / v percent,
Further, the cellulosic tape coated with the gas adsorbent was dipped in a preparation solution prepared by dissolving 15 v / v percent of glycerin in methanol, respectively. Evaporate at room temperature. By such a method, a tape containing 0.3 to 1.4 g of silver paratoluenesulfonate, 0.3 to 3 g of paratoluenesulfonic acid and 25 g of glycerin per square meter can be obtained. .

Further, when the influence of the concentration of silver p-toluenesulfonate on the detection sensitivity was examined, it was found that practical detection sensitivity was obtained if the concentration was 0.3 g or more per square meter as shown in FIG. Can Also, since silver p-toluenesulfonate has extremely low solubility, the maximum amount that can be supported by one coating of the preparation liquid is about 1.4 g / square rice, and even if the concentration is further increased, it is exhibited. It is not a good idea for economic reasons because it consumes a large amount of colorant.

Although phosphine is used as an example in the hydride gas in the above-mentioned embodiments, arsine, diborane, silane, and disilane, which have the same chemical properties as the hydride gas, are common to the color developing agents. (Si ₂ H ₆ ), hydrogen selenide (SeH ₂ ), germane (GeH ₄ ), hydrogen sulfide (H
It was confirmed that the same sensitivity was shown for the detection of other substances such as ₂ S).

[0021]

As described above, in the present invention,
Since a porous tape-shaped carrier containing a gas adsorbent and a humectant was impregnated with silver p-toluenesulfonate as a coloring agent and p-sulfonic acid as a light resistance improver, The low light resistance combined with the improved light resistance due to para-toluene sulfonic acid shows not only extremely high light resistance, but also a hydride gas detection tape that does not reduce the tensile strength of the tape due to strong acid. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of a gas detector using a tape for detecting a hydride gas of the present invention.

FIG. 2 is a diagram showing a calibration curve for phosphine of the tape for detecting hydride gas of the present invention.

FIG. 3 is a diagram showing the relationship between the exposure time and the concentration change rate of a hydride gas detection tape of the present invention and a conventional hydride detection tape.

FIG. 4 is a diagram showing the relationship between the concentration of silver p-toluenesulfonate and the hydride gas detection sensitivity.

Claims (3)

[Claims] 1. Hydrogen obtained by impregnating a breathable cellulose paper piece containing a gas adsorbent and a humectant with silver p-toluenesulfonate as a coloring agent and p-toluenesulfonic acid as a light resistance improver. Compound gas detection tape. 2. The silver paratoluene sulfonate at least 0.3 per square meter of breathable cellulose paper strip.
The hydride gas detection tape of claim 1 comprising grams. 3. A tape for detecting a hydride gas according to claim 1 or 2, wherein said para-toluenesulfonic acid is contained in an amount of 0.3 to 3.0 g per square meter of a breathable cellulose paper piece.