JPH0559502U - Mass flow controller with alarm function for abnormal temperature - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a mass flow controller equipped with an alarm function for an abnormally high temperature, especially during baking, in a non-energized state. [Configuration] A gas inflow path, a sensor section, a bypass section,
In a mass flow controller having a main body provided with a flow rate control valve, a gas outflow passage, and a cover covering the main body, one of the means is that the melting point is 150 ° C to 300 ° C.
Is provided on the cover or the main body, specifically, two contacts connected to the alarm device are provided on the cover or the main body, and a low melting point metal such as solder, bismuth, or selenium is connected between the contacts. When the low melting point metal is melted, the contact is cut off to activate the alarm device to notify the alarm.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a mass flow controller (hereinafter referred to as MFC) that controls a mass flow rate of gas used in a semiconductor manufacturing process.

[0002]

[Prior Art]

 An example of a conventional MFC is shown in FIG. The MFC has a gas inflow path 31, a sensor section 32 for separately flowing the gas in the inflow path 31, a bypass section 33, an outflow path 35 for joining the gas in the sensor section and the bypass section, and the outflow. The main body 30 is provided with a flow rate control valve 34 provided in the middle of the passage and is integrally assembled, and a cover 36 that covers the main body. Further, an amplification circuit 37 for amplifying the detection signal of the sensor section 32, and a comparison control circuit for comparing and controlling the amplified detection signal and a mass flow rate setting signal of a preset mass flow rate and outputting a drive signal to the flow rate control valve. 38 and 38 are usually attached to the main body 30 and housed in the cover 36.

[0003]

[Problems to be solved by the device]

 These MFCs are used in the process gas piping system of the semiconductor manufacturing process, but if a failure or malfunction of the MFC occurs, a large number of defective products will be generated and the production line will be stopped for a long time. There is a possibility that Therefore, conventionally, there has also been proposed an MFC that allows the operating state inside the MFC to be read from the outside and outputs an alarm when an abnormality occurs. (For example, JP-A-3-156509)

However, this method detects the occurrence of an abnormality in the flow rate, and does not prevent the occurrence of the abnormality by detecting the cause of the MFC failure in advance. The piping system of the semiconductor manufacturing line including MFC may be used at room temperature or may be heated to a high temperature depending on the type of gas. Before operating the production line, the piping system including MFC may be heated to a temperature of 200 ° C or higher and baked. In this case, the main body of the MFC may be directly heated by a heater or the like, and the temperature control at this time is often rough control such as ON-OFF control, and the allowable temperature of the MFC (for example, the allowable temperature of the MFC itself). May be heated above 200 ° C). The MFC may have failed due to this heating, but since the user operates the manufacturing line without being able to recognize this anomaly, a problem with the entire manufacturing line may occur, and then some kind of device may become defective. The reality is that you notice that there was something wrong. However, even at this point, it was difficult to find out which device had an abnormality, and it was impossible to determine what caused the abnormality. The present invention provides a mass flow with an alarm function for an abnormal temperature that can detect that an abnormally high temperature is applied to the MFC regardless of whether the MFC is energized or not energized before the MFC fails. It is an object of the present invention to provide a controller and an MFC capable of later investigating the cause of abnormal temperature when an MFC failure occurs.

[0005]

[Means for Solving the Problems]

 According to the present invention, in a mass flow controller having a main body having a gas inflow passage, a sensor portion, a bypass portion, a flow control valve, and a gas outflow passage, and a cover for covering the main body, the temperature inside the cover is A device for issuing an alarm when the temperature exceeds the allowable temperature of the mass flow controller is provided.First, as one means, a substance with a melting point of 150 ° C to 300 ° C is provided on the cover or the main body. Specifically, two contacts connected to the alarm device are provided on the cover or the main body, and a low melting point metal such as solder, bismuth, or selenium is provided between the contacts, and the low melting point metal is melted. In this case, the contact is disconnected to activate an alarm device to notify the alarm. As another means, one of the contacts connected to the alarm device is connected to a bimetal element, which is provided on the cover or the main body, and the alarm device is placed at a position where the bimetal element is displaced according to a preset temperature. When the contact is connected to the other contact, and when the contact is heated to a preset temperature, the contact is made conductive to activate the alarm device and notify the alarm.

[0006]

[Action]

 Of the above-mentioned configurations, the first means uses a thermal fuse, and when the MFC is abnormally heated above its allowable temperature (for example, above 200 ° C), the temperature fuse, such as solder, is used. It melts and interrupts conduction. This activates the alarm device to notify of abnormal heating. Then, in order to investigate the cause of the abnormality, it is possible to easily determine which MFC is the cause of the failure by first checking whether or not this solder is melted. Next, according to the second means, the temperature at which the alarm device is activated can be arbitrarily set by using the bimetal element. That is, since the displacement of the bimetal element corresponding to the temperature can be known in advance, the alarm can be issued by adjusting the distance between one end of the bimetal element and one contact point of the alarm device, that is, the displacement amount of the bimetal bending. The emitted temperature can be set. Further, in this case, the abnormal signal can be issued only while the temperature higher than the set temperature is applied, and the operation can be repeated.

[0007]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an MFC showing an embodiment. The MFC consists of a gas inflow passage 3, a thermal mass flow sensor sensor 4 in which a bridge circuit is formed by winding an electric resistance wire around an inverted U-shaped thin tube, and a plurality of thin tubes that are the same as the thin tubes of the sensor section. A bypass portion 5 configured as described above, a flow rate control valve portion 6 using a laminated piezoelectric element body and a metal diaphragm valve body, and a gas outflow passage 7 are provided, and these are integrally assembled as a main body 1. It A cover 2 is provided on the main body 1 to cover the main body 1. In addition, the circuit parts such as the amplification circuit and the comparison control circuit are separately arranged outside in order to avoid a high temperature, and 8 is a cable therefor.

Next, an alarm function for abnormally high temperature will be described. 10 is a solder having a melting point of about 230 ° C, and its both ends are fixed to the solder mounting posts 11 and 11 'with screws 12 attached. On the other hand, the two solder mounting posts 11 and 11 'are mounted on a substrate 13 made of polyimide resin which is integrally assembled to the main body 1 by a metal fitting 14. The lead wires 15 and 15 'are connected to an external alarm device (not shown). Therefore, the solder functions as a thermal fuse by using the two solder mounting posts as contacts. 16 is a cover body that prevents the solder from melting and scattering. With the above configuration, the heating element is wrapped around the entire MFC during baking, or the entire room is heated to a high ambient temperature of about 200 ° C, so the inside of the cover is 230 ° C. At the above high temperature, the solder is melted and the conduction of the lead wire 15 is interrupted. If the alarm device is activated by this, a failure can be prevented by this alarm.

FIG. 2 shows another embodiment and is an explanatory view of a main part when a bimetal element is used as a means for detecting an abnormal temperature. As the MFC itself, the same one as in the above embodiment is used, and a polyimide resin substrate 21 is attached to the main body at substantially the same position, and one end of the bimetal element 20 is connected to an alarm device (not shown) on this substrate 21. It is attached together with the wire 23 by a stop screw 24, and the other end is curved by temperature, and comes into contact with the adjusting knob 22 for setting the temperature for activating the alarm device after the displacement. The other lead wire 23 connected to the alarm device is connected to the adjusting knob 22, and this knob portion serves as the other contact.

Therefore, since the displacement (bending) amount of the bimetal element with respect to the temperature change is known in advance, if the displacement amount of the bimetal element corresponding to the desired temperature at which the alarm device is desired to be activated is adjusted by the adjustment knob, During baking, if the temperature rises above this set temperature, the contacts will conduct, and the alarm device will activate to prevent accidents. In the case of this embodiment, the temperature at which an alarm is issued can be repeatedly set as described above, and in the case of a temporary temperature rise that is not recognized as an abnormality, there is only an alarm during that time. False positives can be prevented.

[0011]

[Effect of the device]

 According to the MFC of the present invention, it is possible to know a failure of the MFC due to abnormal heating before operating the semiconductor manufacturing line, especially in the baking process, and thus prevent abnormalities in the entire manufacturing line.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mass flow controller showing an embodiment of the present invention.

FIG. 2 is an explanatory view of an alarm function portion showing another embodiment of the present invention.

FIG. 3 is a sectional view of a mass flow controller showing a conventional technique.

[Explanation of symbols]

 1 ... MFC main body 2 ... Cover 3 ... Gas inflow path 4 ... Sensor section 5 ... Bypass section 6 ... Control valve section 7 ... Gas outflow path 10 ... Solder

Claims (3)

[Scope of utility model registration request] 1. A main body having a gas inflow path, a sensor section, a bypass section, a flow rate control valve, and a gas outflow path,
In a mass flow controller having a cover for covering the main body, a device for issuing an alarm when the temperature inside the cover or the main body becomes higher than the allowable temperature of the mass flow controller is provided. Mass flow controller with alarm function. 2. A contact according to claim 1, wherein both contact portions connected to the alarm device are provided in the cover or in the main body, and a low melting point metal such as solder is provided between the contacts, and the low melting point metal such as the solder is A mass flow controller having an alarm function for an abnormal temperature, characterized in that when melted, an alarm is given by disconnecting the contact. 3. A main body having a gas inflow path, a sensor section, a bypass section, a flow rate control valve, and a gas outflow path,
In a mass flow controller having a cover for covering the main body, one contact connected to an alarm device is provided in the cover or in the main body by connecting to the bimetal element, and the bimetal element is displaced at a position corresponding to a preset temperature, Providing the other contact that connects to the alarm device,
A mass flow controller having an alarm function for an abnormal temperature, characterized in that when the temperature is set to a preset temperature, the contact is made conductive to give an alarm.