JP2932075B2 - Hydrogen gas detector - Google Patents

Description

The present invention relates to a method and an apparatus for detecting a hydride gas such as silane gas in a semiconductor manufacturing plant or the like.

[Prior art] Hydrogenated gases such as silane, germane, and stibine are used in large quantities for semiconductor production, but are toxic and flammable, so these hydrogenated gases are highly sensitive and highly responsive. Development of a detection method capable of detection is desired. Conventionally known methods for measuring the concentration of hydrogenated gas, for example, silane gas, include an electrochemical method using a reaction of silane on the electrode surface, an atomic absorption method using a reaction between silane and mercury oxide, or silane and ozone. And a chemiluminescence method utilizing the chemical luminescence of the light.

[Problems to be Solved by the Invention] The conventional detection methods such as the electrochemical method have the drawbacks of insufficient sensitivity and poor selectivity. Further, when a semiconductor type sensor is used, there is a problem that the zero level drifts and the life of the sensor is short, and a small, simple, and easy-to-handle device has not been found.

Means for Solving the Problems According to the present invention, an ozone supply means and an ionization type detection means are provided in a measurement chamber, air containing sampled hydrogenated gas is introduced into the measurement chamber, and ozone is supplied by an ozonizer as the ozone supply means. Is generated, and the generated ozone is supplied to the measurement chamber. In the measurement chamber, the hydrogenated gas and ozone are mixed and reacted to generate fine particle nuclei (hereinafter, referred to as critical nuclei) from the hydrogenated gas. The ionic current in the ion chamber is reduced according to the gas amount of the hydrogenated gas by the generated critical nuclei, and a hydrogenated gas detection device that detects the hydrogenated gas by measuring this ion current with the ionization type detection means is provided. It has been adopted.

[Operation] For example, silane gas is oxidized by ozone to generate critical nuclei of silica. The critical nucleus of silica due to the oxidizing action of ozone is very small and cannot be detected by the photoelectric particle detection method using the dimming method or the scattered light method. You have to go and detect it. The ionization type particle detection method for detecting particles by a change in ion current in an ion chamber ionized by a radiation source can detect even relatively small particles. Therefore, the critical nucleus of silica can be easily detected by using the ionization type detection method. In the method of detecting silane gas as a critical nucleus of silica, a zero-level change does not occur unlike the case of detecting silane gas using a semiconductor-type sensor, so that a stable detection result can be always obtained.

[Embodiment of the Invention] FIG. 1 is an explanatory diagram of a configuration in a case where a silane gas is detected as a hydrogenation gas according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a detection device. The detection apparatus 1 is provided with an ion chamber 2 in the ionization type detection means at the upper part, and an ozonizer 3 as an ozone supply means at the lower part.
The measurement chamber 4 provided with An introduction pipe 5 is connected to the measurement chamber 4, and air containing silane gas is sampled and introduced from a monitoring area such as a semiconductor manufacturing factory. Further, a discharge pipe 7 for discharging air in the measurement chamber 4 is connected by suction means such as a pump (not shown), and an ozone decomposing unit 6 having a catalyst for decomposing ozone is provided at an inlet of the discharge pipe 7, Further, a fan 13 for stirring the inside of the measurement chamber 4 is provided, and an oxygen-containing gas supply pipe 8 for supplying oxygen to the ozonizer 3 is connected near the ozonizer 3 below the introduction pipe 5. Dry oxygen is sufficient as the oxygen-containing gas. A circuit accommodating portion 9 is provided at an upper portion of the ion chamber 2, and constitutes a circuit for transmitting a signal when the magnitude of an ion current based on the generation of a critical nucleus of silica is detected in the ion chamber 2. The signal output from the circuit accommodating section 9 may be an on / off operation, or may be a detection amount of an ion current or the like in the ion chamber 2, and sends this signal to an alarm (not shown).

The above configuration is for the case where air is sampled from various places in the monitoring area (not shown). In the case where devices are provided in various places in the monitoring area, the sampling pipe 5 connected to the measuring chamber 4 is omitted and the air is sampled at that position. An air inlet may be provided. Further, it is preferable that the sample air introduction pipe 5 to be introduced into the measurement chamber 4 be disposed on the ozonizer 3 side, and the discharge pipe 7 for discharging air be disposed on the ion chamber 2 side. The arrangement such as 2 is not limited to the above configuration, and may be provided in reverse or in parallel.

Ozone generated from the ozonizer 3 is toxic and cannot be released to the atmosphere as it is. Therefore, the amount of ozone to be generated must be equal to or less than the amount that can be decomposed by the ozone decomposing unit 6. The catalyst of the ozone decomposition section 6 includes fine powder platinum,
Lead dioxide, manganese dioxide, cupric oxide and the like are used. The ozone decomposing unit 6 does not necessarily need to be provided in the measurement chamber 4 and may be provided in the discharge pipe 7 or at the outlet.

Air is sampled from a monitoring area such as a semiconductor manufacturing factory, and is introduced into the measurement room 4 via the sampling pipe 5. The introduced air is mixed with ozone generated by the ozonizer 3 in the measurement chamber 4, and when air contains silane gas, critical nuclei of silica are generated. The critical nucleus of silica flows into the ion chamber 2 provided at the upper part of the measurement chamber 4 and reduces the ion current in the ion chamber 2. The lowered ion current is detected by the circuit accommodating section 9 provided at the upper part of the ion chamber 2,
The degree of danger is determined by the circuit housing unit 9 itself or a monitoring panel (not shown) and an alarm is issued. The air measured in the measurement chamber 4 is sucked by a pump (not shown) or the like, and is discharged to the outside from the discharge pipe 7 through the ozonolysis unit 6. Measurement room 4
When unreacted ozone is contained therein, the ozone is decomposed by passing through the ozone decomposing unit 6 so that toxic ozone is not released to the outside.

Experimental Example FIG. 2 is an explanatory diagram showing a configuration of an experimental example of the present invention.
The experimental apparatus has an ionization type smoke detector 10 on the upper surface and an ozoneizer 3 on the lower surface.
8.5cm, depth 33cm). An output end of the ionization type smoke detector 10 is connected to a recorder 12 which records an output proportional to the particle concentration of the ionization type smoke detector 10. The ionization type smoke detector 10 is a device similar to a fire detector for detecting smoke density due to a normal fire. The one used in this embodiment does not transmit a fire signal at a predetermined smoke density. This is an analog type in which the magnitude of an ion current that changes due to the critical nucleus of silica generated by mixing silane gas and ozone is detected, and the output is sent out in an analog amount. As the ozonizer 3, a ceramic type used for deodorizing a refrigerator, for example, was used. Recorder 12 was set to record at a rate of 1 cm / min on a scale of 0.5 V / cm.

In the experiment method, silane gas was introduced into the experiment box 11, and ozone was generated by the ozonizer 3, and then the sensor output of the ionization type smoke detector 10 was recorded on the recorder 12. The method of introducing silane gas into the experimental box 11 is, for example, 50 ppm
In the case of, 113 cc of 2% monosilane was injected using a syringe. In a similar manner, the output of the ionizing smoke detector 10 for concentrations from 0 to 200 ppm was measured.

The test box 11 of this experimental example can be reduced in size, and when practical, the components can be efficiently put together.

Experimental Results The results of measuring the output of the ionization type smoke detector 10 with respect to the silane gas concentration C are shown in the graph of FIG. As is clear from the figure, the output voltage V changes in proportion to the density C. From this characteristic, it can be seen that the critical nucleus of silica can be sufficiently detected by the ionization type smoke detector 10. As a result of performing the same experiment using a scattered light type smoke detector as a photoelectric particle detection method instead of the ionization type smoke detector 10, no sensor output was obtained. Therefore, it was found that the critical nucleus of silica was too small to obtain sufficient scattered light.

In the above embodiment, the case of detecting the silane gas using the apparatus of the present invention is exemplified. However, not only the silane gas but also gases such as arsine, stibine, and germane for manufacturing semiconductors can be detected.

[Effects of the Invention] The present invention provides a measurement chamber for generating critical nuclei from a hydrogenated gas, and an introduction hole of the measurement chamber to which an introduction pipe for introducing air containing a hydrogenated gas sampled from a monitored area is connected. Ozone supply means for supplying ozone disposed in the vicinity of the introduction hole in the measurement chamber, and the measurement chamber is mixed so that ozone supplied from the ozone supply means and air introduced from the introduction hole are mixed. A stirring fan, an ionization-type detection unit in the measurement chamber that measures an ion current in the ionization chamber that changes due to a critical nucleus generated from the hydrogenated gas, and an ionization-type detection unit in the measurement chamber that is disposed near the ionization-type detection unit. A hydrogenated gas detector comprising: a discharge hole of the measurement chamber for discharging air;

As a result, the test box 11 can be reduced in size, and when practical, the components can be efficiently put together.

That is, the present invention is configured to introduce the sampled air into the measurement chamber, mix it with ozone so as to generate sufficient critical nuclei in the measurement chamber, and simultaneously detect the hydrogenated gas in the ion chamber in the measurement chamber. It was done. Therefore, since the hydrogenated gas can be detected as it is by generating sufficient critical nuclei in the measurement chamber, the effect of significantly improving the response as well as the detection efficiency is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a configuration of an embodiment of the present invention, FIG. 2 is an explanatory view showing a configuration of an embodiment of the present invention, and FIG. 3 is a diagram showing a relationship between silane gas concentration and output voltage. In the figure, 1 is a detection device, 2 is an ion chamber, 3 is an ozonizer, 4 is a measurement chamber, 5 is an inlet tube (inlet hole), 6 is an ozone decomposing unit, 7 is an outlet tube (outlet hole), and 8 is oxygen-containing. A gas supply pipe, 9 is a circuit accommodating section, 10 is an ionization type smoke detector, 11 is a laboratory box, 12 is a recorder, and 13 is a fan.

Claims (2)

(57) [Claims] 1. A measuring chamber for generating critical nuclei from a hydrogenated gas, an inlet of the measuring chamber to which an introduction pipe for introducing air containing a hydrogenated gas sampled from a monitoring area is connected; An ozone supply means for supplying ozone disposed near the introduction hole, and a fan for stirring the measurement chamber so as to mix ozone supplied from the ozone supply means and air introduced from the introduction hole. An ionization-type detection means in the measurement chamber for measuring an ion current in the ionization chamber, which is changed by a critical nucleus generated from the hydrogenated gas, and exhausting air in the measurement chamber disposed near the ionization-type detection means. A hydrogen gas detection device comprising: a discharge hole of the measurement chamber; 2. The hydrogenated gas detecting device according to claim 1, wherein said ionization detecting means has sensitivity to a concentration of up to 200 ppm.