Diaphragm vacuum gauge

Abstract

To facilitate switching of heating temperature set values.SOLUTION: A diaphragm gauge comprises: a pressure receiving unit 10 whose electrical characteristics change according to displacement of a diaphragm due to the pressure of a medium to be measured; a heater 5 that heats the pressure receiving unit 10; a temperature sensor 9 that measures the temperature of the pressure receiving unit 10; a pressure measuring unit 2021 that converts the change in electrical characteristics of the pressure receiving unit 10 into a pressure measurement value; a storage unit 203 that stores a plurality of heating temperature set values; a heating temperature setting unit 2024 that selects any one of the plurality of heating temperature set values according to a digital input signal input from the outside; and a control unit 2023 that controls power supplied to the heater 5 based on the temperature measured by the temperature sensor 9 and the heating temperature set value selected by the heating temperature setting unit 2024.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a diaphragm vacuum gauge.

Background Art

[0002] A diaphragm vacuum gauge is used for measuring the pressure in a semiconductor process chamber. If the temperature of the semiconductor process gas is not appropriate, it will liquefy or solidify and adhere to the sensor part of the diaphragm vacuum gauge, affecting the measurement. Therefore, the diaphragm vacuum gauge has a self-heating function to prevent the adhesion of the liquefied or solidified process gas (see Patent Document 1, Patent Document 2, Patent Document 3).

[0003] On the other hand, in recent years, semiconductor processes have become more advanced, and various gases are used in one process. Since the appropriate self-heating temperature may vary depending on the process gas, there is also a diaphragm vacuum gauge having a function of switching the self-heating temperature, such as those disclosed in Patent Document 2, Patent Document 3, and Patent Document 4. Furthermore, there are also those equipped with a function of turning off the self-heating function to reduce power consumption when the diaphragm vacuum gauge is not in use.

[0004] However, in the conventional diaphragm vacuum gauge, there is a problem that in order to change the self-heating temperature, the user has to input the heating temperature set value into the diaphragm vacuum gauge through communication or analog input.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a diaphragm vacuum gauge capable of easily switching a heating temperature set value without inputting the heating temperature set value by communication or analog input.

Means for Solving the Problems

[0007] The diaphragm vacuum gauge of the present invention includes a pressure receiving portion configured such that its electrical characteristics change in accordance with displacement of a diaphragm due to the pressure of a medium to be measured, a heater configured to heat the pressure receiving portion, a temperature sensor configured to measure the temperature of the pressure receiving portion, a pressure measurement portion configured to convert a change in the electrical characteristics of the pressure receiving portion into a pressure measurement value, a storage portion configured to store a plurality of heating temperature set values in advance, a heating temperature setting portion configured to select any one of the plurality of heating temperature set values in accordance with a digital input signal input from the outside, and a control portion configured to control the power supplied to the heater based on the temperature measured by the temperature sensor and the heating temperature set value selected by the heating temperature setting portion A digital input circuit configured to convert the ON / OFF of the digital input signal into a voltage and input it to the heating temperature setting unit and is characterized by comprising the same. Further, one configuration example of the diaphragm vacuum gauge of the present invention is further characterized by comprising a changing portion configured to change at least one of the plurality of heating temperature set values stored in the storage portion in accordance with an instruction from a user 。

Advantages of the Invention

[0008] According to the present invention, by providing a storage portion and a heating temperature setting portion, a user does not need to input a heating temperature set value by communication or analog input, and can easily switch the heating temperature set value only with a digital input signal.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0010] [Principle of the Invention] The inventor has conceived that a diaphragm vacuum gauge is made to hold a plurality of heating temperature setting values in advance as parameters so that a user can select a heating temperature setting value with a Digital Input (hereinafter referred to as DI) signal. As a result, the user does not need to input a heating temperature setting value by communication or analog input, and can switch the heating temperature setting value only with a simple ON / OFF signal of a switch.

[0011] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a block diagram showing the configuration of a diaphragm vacuum gauge according to an embodiment of the present invention, and Figure 2 is a cross-sectional view showing the configuration of a main part of a sensor chip used in the diaphragm vacuum gauge.

[0012] The diaphragm vacuum gauge includes a pressure receiving part 10 whose capacitance changes according to the displacement of a diaphragm (diaphragm) due to the pressure of a medium to be measured (for example, a process gas), and a circuit part 11 that converts the change in the capacitance of the pressure receiving part 10 into a pressure measurement value.

[0013] A recess is formed in the central portion of the pedestal 101 of the sensor chip 1 of the pressure-receiving portion 10. A diaphragm 102 configured to be deformable in accordance with the pressure P of the medium to be measured is joined to the surface of the pedestal 101 in which the recess is formed. The recess in the pedestal 101 forms a reference vacuum chamber 104 together with the diaphragm 102.

[0014] In the sensor chip 1, a fixed electrode 105 is formed on the surface of the pedestal 101 on the reference vacuum chamber 104 side, and a movable electrode 106 is formed on the surface of the diaphragm 102 on the reference vacuum chamber 104 side so as to face the fixed electrode 105. In this way, the fixed electrode 105 and the movable electrode 106 are arranged so as to face each other with a gap therebetween. When the diaphragm 102 is deflected by receiving the pressure P of the medium to be measured, the distance between the movable electrode 106 and the fixed electrode 105 changes, and the capacitance between the movable electrode 106 and the fixed electrode 105 changes. The pressure P of the medium to be measured received by the diaphragm 102 can be detected from this change in capacitance. The diaphragm constituent member 100 and the pedestal 101 are made of an insulator such as sapphire, for example.

[0015] The diaphragm vacuum gauge shown in FIG. 1 includes the sensor chip 1 configured as described above, a housing 2 that houses the sensor chip 1, a pressure introduction pipe 3 that guides the pressure P of the medium to be measured to the diaphragm 102 of the sensor chip 1, a sensor case 4 that covers the housing 2, and a heater 5 provided so as to surround the outer peripheral surface of the sensor case 4. The sensor case 4 provided with the heater 5 is covered with a heat insulating material 6.

[0016] Inside the housing 2, a partition wall 7 is provided. The partition wall 7 is composed of a pedestal plate 7a and a support plate 7b, and separates the internal space of the housing 2 into a first space 2a and a second space 2b. The outer periphery of the support plate 7b is fixed to the housing 2, and supports the pedestal plate 7a in a state of floating within the internal space of the housing 2. The sensor chip 1 is fixed to the second space 2b side of the pedestal plate 7a. Further, a pressure introduction hole 7c for guiding the pressure in the first space 2a to the diaphragm 102 of the sensor chip 1 is formed in the pedestal plate 7a. The second space 2b communicates with the reference vacuum chamber 104 of the sensor chip 1 and is in a vacuum state.

[0017] The pressure introduction pipe 3 is connected to the first space 2a side of the housing 2. A baffle 8 is provided between the pressure introduction pipe 3 and the housing 2. The medium to be measured introduced from the pressure introduction pipe 3 hits the plate surface of the baffle 8 and flows into the first space 2a of the housing 2 through the gaps around the baffle 8. A temperature sensor 9 is provided on the outer wall surface of the housing 2. The temperature sensor 9 measures the temperature of the housing 2 as the temperature of the pressure receiving part 10.

[0018] FIG. 3 is a block diagram showing the configuration of the circuit unit 11. The circuit unit 11 includes a signal detection unit 200 that outputs a signal having an amplitude proportional to the capacitance between the movable electrode 106 and the fixed electrode 105, an AD conversion unit 201 that converts the outputs of the signal detection unit 200 and the temperature sensor 9 into digital signals, an arithmetic processing unit 202, a storage unit 203 that stores the program and data of the arithmetic processing unit 202, a DA conversion unit 204 that converts the output of the arithmetic processing unit 202 into an analog signal, a communication port 205 for communication with the outside, and a digital input circuit 206 that converts the ON / OFF of the DI signal into a voltage and inputs it to the arithmetic processing unit 202.

[0019] As shown in FIG. 3, the arithmetic processing unit 202 includes a capacitance calculation unit 2020 that calculates the capacitance (electrical characteristics) between the movable electrode 106 and the fixed electrode 105 of the pressure receiving unit 10, a pressure measurement unit 2021 that converts the change in capacitance into a pressure measurement value, a temperature detection unit 2022 that acquires the temperature value measured by the temperature sensor 9, a control unit 2023 that controls the power supplied to the heater 5 based on the temperature measured by the temperature sensor 9 and the heating temperature set value, a heating temperature setting unit 2024 that selects any one of a plurality of heating temperature set values according to the states of the input ports PI1 to PI4, and a change unit 2025 that changes at least one of the plurality of heating temperature set values stored in the storage unit 203 according to an instruction from the user.

[0020] The digital input circuit 206 is composed of transistors Q1 to Q4 in which DI signals DI1 to DI4 are input to the base terminals, the power supply voltage VCC is supplied to the emitter terminals, and the collector terminals are connected to the input ports PI1 to PI4 of the arithmetic processing unit 202, and resistors R1 to R4 whose one ends are connected to the input ports PI1 to PI4 and the other ends are connected to the ground.

[0021] FIG. 4 is a flowchart for explaining the operation of the arithmetic processing unit 202. The capacitance calculation unit 2020 calculates the capacitance value between the movable electrode 106 and the fixed electrode 105 from the amplitude of the output signal of the signal detection unit 200 (step S100 in FIG. 4).

[0022] The pressure measurement unit 2021 converts the change in capacitance calculated by the capacitance calculation unit 2020 into a pressure measurement value (step S101 in FIG. 4). The pressure measurement value calculated by the pressure measurement unit 2021 is converted into an analog signal by the DA conversion unit 204 and output to the outside. Also, the pressure measurement value is transmitted to an external device (for example, a computer) via the communication port 205.

[0023] Next, the storage unit 203 stores a plurality of heating temperature setting values in advance. As described above, the user can select one of these heating temperature setting values with a DI signal. Specifically, the user connects a PLC (programmable logic controller) or the like to the digital input terminal of the diaphragm vacuum gauge and uses the switches SW1 to SW4 of the PLC to turn the DI signals DI1 to DI4 ON / OFF. Table 1 shows an example of selecting a heating temperature setting value by turning the DI signals DI1 to DI4 ON / OFF.

[0024]

Table 1

[0025] In the example of Table 1, it is possible to select one of the 16 heating temperature setting values of parameters 1 to 16 by turning the 4 DI signals DI1 to DI4 ON / OFF. For example, when all the switches SW1 to SW4 are turned OFF and all the DI signals DI1 to DI4 are turned OFF, the transistors Q1 to Q4 of the digital input circuit 206 turn OFF, and the voltages of the input ports PI1 to PI4 of the arithmetic processing unit 202 become Low.

[0026] The heating temperature setting unit 2024 monitors the states of the input ports PI1 to PI4, selects and reads out a heating temperature setting value (self-heating temperature selection parameter) corresponding to the states of the input ports PI1 to PI4 from the storage unit 203 (step S102 in FIG. 4). Then, the heating temperature setting unit 2024 sets the read heating temperature setting value for the control unit 2023 (step S103 in FIG. 4).

[0027] The temperature detection unit 2022 acquires the temperature value measured by the temperature sensor 9. The control unit 2023 controls the power supplied to the heater 5 so that the temperature measured by the temperature sensor 9 matches the heating temperature setting value (step S104 in FIG. 3).

[0028] For example, when all of the DI signals DI1 to DI4 are OFF (the input ports PI1 to PI4 are Low) as in the above example, the heating temperature setting unit 2024 reads parameter 1 from the storage unit 203. In the example of Table 1, since parameter 1 is self-heating OFF, the control unit 2023 does not supply power to the heater 5.

[0029] Also, when switches SW1 to SW3 are OFF and switch SW4 is ON, and DI signals DI1 to DI3 are OFF and DI signal DI4 is ON, transistors Q1 to Q3 are OFF and transistor Q4 is ON, and the voltages of input ports PI1 to PI3 are Low and the voltage of input port PI4 is High. In this case, the heating temperature setting unit 2024 reads parameter 2 from the storage unit 203. In the example of Table 1, since parameter 2 is 50°C, the control unit 2023 supplies power to the heater 5 so that the temperature measured by the temperature sensor 9 becomes 50°C.

[0030] The arithmetic processing unit 202 performs the processing of steps S100 to S104 at each measurement cycle until the pressure measurement operation ends according to, for example, a user's instruction (YES in step S105 of FIG. 4).

[0031] Note that the heating temperature setting value (self-heating temperature selection parameter) stored in the storage unit 203 can be changed by the user, for example, through communication via the communication port 205 or by a digital setter. The change unit 2025 changes at least one of the plurality of heating temperature setting values stored in the storage unit 203 according to an instruction from the user. Thereby, for example, parameter 16 can be changed from 200°C to 190°C.

[0032] As described above, in this embodiment, the heating temperature setting value can be easily switched only by the DI signal, so communication and setting with an analog signal are not required, and the burden on the device side is reduced. In this embodiment, since the heating temperature setting value can be switched by a PLC or the like connected to the digital input terminal, the heating temperature setting value can be easily changed, for example, during a semiconductor process, according to the PLC program.

[0033] In addition, in a conventional diaphragm vacuum gauge, the user has to input the heating temperature set value into the diaphragm vacuum gauge through communication or analog input. However, when changing the heating temperature set value through communication or analog input, there is a possibility of accidentally setting an unplanned value. In contrast, in this embodiment, since the selection is made from the heating temperature set values stored in the storage unit 203 in advance, an unplanned value will not be set.

[0034] Note that in this embodiment, four DI signals are used as DI1 to DI4, but only one DI signal may be used. When there is one DI signal, there are two selectable heating temperature set values.

[0035] In addition, in this embodiment, a capacitance-type diaphragm vacuum gauge in which the capacitance changes according to the displacement of the diaphragm has been described, but the present invention is not limited thereto, and the present invention may be applied to other types of diaphragm vacuum gauges. As an example of other types of diaphragm vacuum gauges, for example, there is a piezoresistive diaphragm vacuum gauge that uses a semiconductor silicon with a diffused resistor formed as a diaphragm and converts the resistance change of the resistor according to the displacement of the diaphragm into a pressure measurement value.

[0036] The arithmetic processing unit 202 described in this embodiment can be realized by a computer including a CPU (Central Processing Unit), a storage device, and an interface, and a program for controlling these hardware resources. A configuration example of this computer is shown in FIG. 5.

[0037] The computer includes a CPU 400, a storage device 401, and an interface device (I / F) 402. Connected to the I / F 402 are a heater 5, an AD conversion unit 201, a DA conversion unit 204, a communication port 205, and the like. In such a computer, a program for realizing the method of the present invention is stored in the storage device 401. The CPU 400 executes the processing described in this embodiment according to the program stored in the storage device 401.

Industrial Applicability

[0038] The present invention can be applied to a diaphragm vacuum gauge.

Explanation of Signs

[0039] 1... Sensor chip, 5... Heater, 9... Temperature sensor, 10... Pressure receiving part, 11... Circuit part, 102... Diaphragm, 105... Fixed electrode, 106... Movable electrode, 200... Signal detection part, 201... AD conversion part, 202... Arithmetic processing part, 203... Storage part, 204... DA conversion part, 205... Communication port, 206... Digital input circuit, 2020... Capacitance calculation part, 2021... Pressure measurement part, 2022... Temperature detection part, 2023... Control part, 2024... Heating temperature setting part, 2025... Change part, Q1 to Q4... Transistors, R1 to R4... Resistors.

Claims

1. A pressure-receiving part configured such that its electrical characteristics change according to the displacement of a diaphragm due to the pressure of a medium to be measured; A heater configured to heat the pressure-receiving part; A temperature sensor configured to measure the temperature of the pressure-receiving part; A pressure measurement part configured to convert the change in the electrical characteristics of the pressure-receiving part into a pressure measurement value; A storage part configured to store a plurality of heating temperature setting values in advance; A heating temperature setting part configured to select any one of the plurality of heating temperature setting values according to a digital input signal input from the outside; A control part configured to control the power supplied to the heater based on the temperature measured by the temperature sensor and the heating temperature setting value selected by the heating temperature setting part; A diaphragm vacuum gauge, comprising a digital input circuit configured to convert the ON / OFF of the digital input signal into a voltage and input the voltage to the heating temperature setting part.

2. The diaphragm vacuum gauge according to Claim 1, further comprising a change part configured to change at least one of the plurality of heating temperature setting values stored in the storage part according to an instruction from a user.

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