JPH0412270A - Silicon hydride detector - Google Patents

Abstract

PURPOSE:To stably detect silicon hydride with a good sensitivity over a long period of time with simple constitution by humidifying a gaseous sample contg. the silicon hydride, then bringing the gaseous sample into reaction with water at ordinary temp. in the presence of a catalyst consisting of an alkaline salt and detecting the generated hydrogen. CONSTITUTION:A suction pump 2 is run to introduce the gaseous sample into a humidifying chamber 3 where the gaseous sample is humidified to >=40% relative humidity. The H2 of 4 times SiH4 is generated if the ordinary-temp. reaction of SiH4+2 H2O SiO2+4H2 is effected in the presence of the catalyst 14 of a reaction chamber 10 by passing the gaseous sample in an A line 11 first if, for example, the SiH4 is contained in the gaseous sample,. Then, the H2 is not generated and a large change arises in the concn. of the H2 detected 16 between both lines 11 and 12 if this gas is passed to the B line 12. Both are, thereupon, compared and the presence and concn. of the silicon hydride are detected. This apparatus brings the silicon hydride into reaction with the water in the presence of the catalyst consisting of the alkaline salt and, therefore, a large amt. of the H2 is generated and the detection sensitivity is improved. Since the heated catalyst is not used, the constitution is simplified and the detection stable over a long period of time is executed.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a silicon hydride detection device.

[Conventional technology]

Known methods for detecting silicon hydrides such as monosilane (SiHn) and disilane (SizH6) include constant potential electrolysis, galvanic cell method, chemiluminescence method, metal oxide semiconductor method, IR method, and UV method.

However, among the above detection methods, in the constant potential electrolysis method, galvanic cell method, chemiluminescence method, and metal oxide semiconductor method, silicon dioxide (
S i O □) may adhere to the detection part, or S i O
There is a drawback that initial detection performance cannot be maintained due to dissolution of Oz, and chemiluminescence method, IR
In the method and UV method, maintenance is quite troublesome, such as a thin film of 5iO7 adhering to the optical system and making it unusable in a short period of time, and silicon hydride cannot be detected stably over a long period of time. I couldn't.

Therefore, as a solution to the above-mentioned problems,
As shown in Japanese Patent No. 1-117452, it has been proposed to decompose silicon hydride by passing it through a heated catalyst layer and to detect hydrogen (H2) produced at the time.

[Problem to be solved by the invention]

However, in this detection method, for example, 5iH
When detecting s, a catalyst is used to detect S i H, +O,
→Since only S r Ha is decomposed by the reaction SiO□+2H2, 21
) pnl H2 is generated, so there are drawbacks such as low detection sensitivity and the drawback that the catalyst has to be heated, making the device configuration that much more complicated.

The present invention has been made with the above-mentioned considerations in mind, and an object of the present invention is to detect silicon hydride that has a simple configuration and is capable of detecting silicon hydride stably and sensitively over a long period of time. The goal is to provide equipment.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the silicon hydride detection device according to the present invention humidifies a sample gas containing silicon hydride as necessary, and then humidifies it under a catalyst made of an alkaline salt. The unique feature is that silicon hydride and water are reacted at room temperature, and the hydrogen produced at that time is detected.

(Function) In the silicon hydride detection device of the present invention having the above characteristic configuration, silicon hydride contained in the sample gas reacts with water at room temperature under a catalyst made of an alkaline salt. When Hs is included, the reaction SiH4+2H20→5iOr-1-4Hz is carried out at room temperature, and from 1 ppm SiH to 4 ppm
Since OH2 is generated, H2 can be detected with high sensitivity. Furthermore, since there is no need to heat the catalyst, the configuration of the device becomes simpler.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an example of a silicon hydride detection device according to the present invention. In this figure, 1 is a sample gas inlet, which is connected to a gas line not shown. 2 is a suction pump that sucks a certain amount of sample gas, and 3 is a humidification tank that humidifies the sample gas sucked by suction pump 2 so that the relative humidity (RH) thereof becomes 40% or more. This humidifying tank 3 is constructed by placing pure water 5 in a container 4 made of PVC (polyvinyl chloride), for example, and connecting a silicon tube 7 with an appropriate inner diameter for moisture diffusion to a piping 6 connected to the suction pump 2. 7 is immersed in pure water 5, and the humidification operation in this humidifying tank 3 is to cause silicon hydride and water (H, O) to react in a reaction tank 10, which will be described later.
This is done in order to keep the detection sensitivity of the hydrogen detector 16, which will be described later, constant. Note that the RH of the sample gas is always 40%.
If this is the case, the humidifying tank 3 may be omitted.

Reference numeral 8 denotes a switching valve consisting of, for example, a three-way electromagnetic valve, the upstream side of which is connected to the humidifying tank 3 via piping 9, and the downstream side connected to an A line 11 having a reaction tank 10 and a B line that bypasses the reaction tank 10. Line 12 is connected. The switching valve 8 is switched at regular intervals by a control signal from a control device (not shown), so that the A line 11 and the B line 1
The sample gas is made to flow alternately between the two. The reaction tank 10 is constructed by filling a corrosion-resistant cylinder 13 with a catalyst 14 made of, for example, an alkaline salt obtained by soaking porous alumina in a saturated sodium carbonate solution and then drying and solidifying it at 150°C. is sealed with a filter 15, and if the sample gas contains, for example, S i H4,
The reaction H4+2HzO→5i02+4H2 is supposed to take place at room temperature.

Reference numeral 16 denotes a hydrogen detector whose main component is, for example, SnO□, which is provided downstream of the confluence 17 of both lines IL 12, and is capable of detecting H2 and measuring its concentration. 18 is a sample gas outlet.

In addition, as mentioned above, the reason why the A line 11 in which the reaction tank 10 exists on the downstream side of the humidification tank 3 and the B line 12 which bypasses the reaction tank 10 are provided is as follows.

That is, the sample gas taken in through the sample gas population 1 may contain H2 in addition to silicon hydride; in such cases, the sample gas that has passed through the reaction tank 10 is introduced into the hydrogen detector 16. Detector output and reaction tank 10 when
This is so that it can be determined whether the hydrogen detector 16 is responding to silicon hydride or H2 by comparing the detector output when a sample gas that has not passed through the hydrogen detector 16 is introduced into the hydrogen detector 16. be.

FIG. 2 is a block diagram showing an example of the electrical configuration of the silicon hydride detection device. In this figure, 19 is an amplifier that amplifies the output from the hydrogen detector 16, and 20 is a switching valve 8.
The sample gas is passed through the A line 11 to the hydrogen detector 1.
6 and a hold amplifier that bolds the signal output from the hydrogen detector 16 at that time, and 21 operates the switching valve 8 to pass the sample gas through the B line 12 to the hydrogen detector 16.
This is a hold amplifier that holds the signal output from the hydrogen detector 16 at that time. 22 is a concentration indicator that displays the concentration of silicon hydride based on the H2 concentration measured by the hydrogen detector 16; 23 is a hold amplifier 20;
．． A differential amplifier takes the difference between the outputs of 21, and 24 is a comparator.

25 and 26 are gas type indicators; when the sample gas contains H, the indicator 25 lights up, and when the sample gas contains silicon hydride, the indicator 26 lights up. , and when H2 and silicon hydride are included, the screen displays 25 and 26 light up.

The operation of the silicon hydride detection apparatus having the above structure will now be described with reference to the time chart shown in FIG.

By operating the suction pump 2, the sample gas is introduced into the humidifying tank 3 via the sample gas population 1, and by passing through the silicon tube 7 for moisture diffusion, the sample gas is adjusted to RH.
It is humidified to over 40%. The humidified sample gas is sent to the switching valve 8, and by switching the switching valve 8, the sample gas is caused to flow intermittently into the A line 11 and the B line 12 at regular intervals.

■When the sample gas contains only 5iHa, first, when the sample gas flows through the A line 11, in the reaction tank 10, under the catalyst 14, S i Hi + 2H 20 → Si○ 2 + 4H 2...
・(1) The reaction at room temperature is carried out, and H2 is 4 times that of SiH.
occurs. Next, when the sample gas flows through the B line 12 by switching the switching valve 8, SiH< and H2
It does not react with 0. Therefore, H in the hydrogen detector 16
2 concentration changes as shown in FIG. 3(A). In this figure, the sample gases A and B are respectively A line 11.
It shows when it is flowing on the B line 12.

When the sample gas contains only H2, the sample gas is transferred to the A line 11 by switching the switching valve 8.
Since the reaction represented by the above equation (1) does not occur in the reaction tank 10 even if H2 flows, the H2 concentration in the hydrogen detector 16 changes as shown in FIG. 3(B).

In addition, ■When the sample gas contains 5iHa and H2, the H21 degree in the hydrogen detector 16 is as shown in Fig. 3 (C
).

In the silicon hydride detection device having the above configuration, it is possible to detect S i H4 contained in the sample gas and measure its concentration. In particular, the detector output when the sample gas that has passed through the reaction tank 10 is introduced into the hydrogen detector 16 is compared with the detector output when the sample gas that has not passed through the reaction tank 10 is introduced into the hydrogen detector 16. Therefore, it is possible to determine whether the hydrogen detector 16 is responding to silicon hydride or H2.

It should be noted that the present invention is not limited to the above-described embodiments, and other hydrides such as sibosilane and phosphine can also be detected. Further, the catalyst 14 provided in the reaction tank 10 may be made of other alkaline salts than sodium carbonate, such as calcium carbonate and calcium hydroxide.

〔Effect of the invention〕

As explained above, in the present invention, after humidifying a sample gas containing silicon hydride as necessary, silicon hydride and water are reacted at room temperature under a catalyst made of an alkaline salt, and the hydrogen produced at that time is Since the detection is performed, the following effects are achieved.

■ Because silicon hydride is reacted with H and O, H
2 is generated in large quantities, and the more sensitive it can be detected.

■ Since no heated catalyst is used, the overall structure of the device is simple, and even if a large amount of silicon hydride flows in, it will not ignite.

■ Interference effects due to H2 can be prevented.

■ Stable detection can be performed over a long period of time.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a block diagram showing an example of a silicon hydride detection device according to the present invention, and FIG. 2 is a block diagram showing its electrical configuration. , Figure 3 (AL) (B) and (C) are time charts showing the output of the hydrogen detector. 3... Humidification tank, 8... Switching valve, 10... Reaction tank, 14. Catalyst. , 16... hydrogen detector.

Claims (1)

[Claims] After humidifying the sample gas containing silicon hydride as necessary,
A silicon hydride detection device characterized in that silicon hydride and water are reacted at room temperature under a catalyst made of an alkaline salt, and the hydrogen produced at the time is detected.