JPH0639294Y2 - Masflo controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement of a mass flow controller used for controlling the flow rate of a supply gas used in semiconductor manufacturing.

[Prior art] Conventionally, when manufacturing semiconductors, diffusion, vapor phase growth, CV
Various atmosphere gases are supplied in steps such as D, and a mass flow controller 100 as shown in a cross section of a main part in FIG. 2 is used in order to accurately control the flow rate of the supplied gas. The mass flow controller 100 is composed of a mass flow controller main body 100a and a cover 100b that covers the mass flow controller main body 100a. A gas inlet 2 for the supply gas is provided at one end of the mass flow controller main body 100a, and a gas outlet 3 for the supply gas is provided at the other end. A sensor 4 and a bypass 5 having a larger area than the sensor 4 are provided near the gas inlet 2. A gas flow control valve 6 is provided on the secondary side of the sensor 4 and the bypass 5. The sensor 4 has a structure in which, for example, a self-heating resistor 4a connected to the bridge circuit 110 is wound, and the temperature difference generated by the flow rate of gas flowing in the sensor 4 is detected to detect the inside of the sensor 4. The flow rate of the supply gas flowing through is detected. Above bridge circuit
An amplifier circuit 111 is connected to 110, and when its output voltage is sent to a comparison control circuit 112, it is compared with a preset set voltage, the flow control valve 6 is controlled, and the gas is discharged from the gas outlet 3. The gas flow rate is controlled.

Further, in the mass flow controller main body 100a as described above, a material having good corrosion resistance is used so that the gas-contact upper part 7a and the gas-contact lower part 7b are not corroded by the highly corrosive supply gas such as HCl gas. . And sensor 4
The parts to which the gas flow control valve 6 is attached are sealed by O-rings 8a, 8b and the like and sealing parts 9a, 9b, etc., each of which has a good sealing property, to prevent leakage of the supply gas.

In the mass flow controller 100 having such a structure, a part of the supply gas that has entered the mass flow controller main body 100a from the gas inlet 2 flows through the sensor 4 and most flows through the bypass 5, and joins again on the respective secondary sides. .
Even if the flow rate of the supply gas flowing from the gas inlet 2 changes at this time, the gas flow rate flowing through the sensor 4 and the bypass 5 is a constant value determined by the cross-sectional area ratio of the former. , Mass flow controller 100
It has a correlation with the total flow rate of the gas entering it. The temperature difference generated according to the flow rate of the supply gas flowing into the sensor 4 is detected by the self-heating resistor 4a, sent to the amplifier circuit 111 as a minute voltage by the bridge circuit 110, and amplified by the amplifier circuit 111. It is sent to the comparison control circuit 112. In the comparison control circuit 112, the output voltage from the amplifier circuit 111 is compared with a preset voltage set according to a desired gas flow rate, and the flow control valve 6 is controlled according to the difference to supply gas at a desired flow rate. Will be delivered from the gas outlet 3.

[Problems to be solved by the invention]

However, in the mass flow controller 100 having the above-mentioned structure, even though it is sealed by the O-rings 8a, 8b and the seal portions 9a, 9b having a good sealing property so that the supply gas does not leak, the mass flow controller 100 can be used for a long time. Corrosion occurs,
The supply gas may leak from the connection gaps a, b, c, d. If the supply gas leaks and accumulates in the cover 100b in such a state, it may cause an explosion depending on the type of the gas, or if it is a highly toxic gas, the gas leaks from the cover 100b to the outside. It is dangerous and becomes a big problem that affects human life.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and includes a supply gas inlet, a sensor, a bypass,
In a mass flow controller having a mass flow controller main body having a flow rate control valve and a supply gas outlet, and a cover covering the mass flow controller main body, an inspection gas inlet and an inspection gas outlet are provided in the cover, and an inspection gas is mixed from the inspection gas outlet. It is characterized in that a gas detector for detecting the supply gas discharged as a result is provided.

[Function of device]

With this configuration, the inspection gas inlet provided in the cover supplies the inspection gas of a different type from the supply gas, and the inspection gas can be discharged from the inspection gas outlet. Therefore, even if the supply gas leaks into the cover, it can be mixed with the inspection gas and discharged from the inspection gas outlet 3. Since this exhaust gas flows into the gas detector that reacts with the supply gas, it is possible to immediately detect that the supply gas is mixed with the exhaust gas. Therefore, it is possible to reliably detect the leakage of the supply gas and avoid the risk of explosion or leakage of highly toxic gas to the outside of the cover.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an essential part of a mass flow controller 1 according to the present invention. In the drawing, the structure is the same as that of FIG. 2 except for the inspection gas inlet 10a and the inspection gas outlet 10b provided in the cover 10, and therefore the same parts are designated by the same reference numerals and the description thereof is omitted. Now, as shown in the figure, a joint 11 for connecting, for example, a pipe 11a for supplying the inspection gas is fitted to the inspection gas inlet 10a provided at substantially the center of the side wall of the cover 10. Further, an inspection gas outlet 10b is provided at approximately the center of the side wall which preferably faces the inspection gas inlet 10a. A joint 12 is connected to the inspection gas outlet 10b, for example, a pipe 12a for discharging the inspection gas supplied from the inspection gas inlet 10a.
Is fitted. The gas detector 13 is connected to the pipe 12a. This gas detector 13 reacts with the gas supplied from the supply gas inlet 2, and the supply gas flowing out from the gap parts a, b, c, d of the mass flow controller main body 100a in the exhausted inspection gas. If it is included, it can be easily detected. When the gas detector 13 detects the gas supplied from the supply gas inlet 2, for example, it is preferable to use one having a configuration that, for example, generates a sound or light to warn.

In the mass flow controller 1 having such a configuration, when the supply gas supplied from the supply gas inlet 2 leaks into the mass flow controller body cover 10 through the respective connection gap portions a, b, c, d, the leaked supply gas Is mixed with the inspection gas and is discharged from the inspection gas outlet 10b, so that the gas detector 13 can reliably detect the gas leakage. Here, the gas detector 13 is connected through the pipe 12a, but when directly attached to the joint 12,
It becomes more preferable.

[Effect of device]

As is clear from the above description, according to the mass flow controller of the present invention, even if the supply gas leaks into the cover, it can be immediately detected by the gas detector. The danger of gas leaking to the outside of the cover is reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a mass flow controller according to an embodiment of the present invention, and FIG. 2 is a sectional view of an essential part of a conventional mass flow controller. (Description of symbols) 1 ... mass flow controller, 100a ... mass flow controller main body, 2 ... supply gas inlet 3 ... supply gas outlet 4 ... sensor, 5 ... bypass, 6 ... flow control valve, 10 ... … Cover, 10a …… Inspection gas inlet, 10b …… Inspection gas outlet, 13 …… Gas detector.

Claims (1)

[Scope of utility model registration request] 1. A mass flow controller having a supply gas inlet, a sensor, a bypass, a flow rate control valve and a supply gas outlet, and a mass flow controller having a cover for covering the mass flow controller main body. A mass flow controller comprising an inlet, an inspection gas outlet, and a gas detector for detecting a supply gas mixed with the inspection gas and discharged from the inspection gas outlet.