Piezoelectric element diagnosis device, piezoelectric element diagnosis method, piezoelectric element diagnosis program, fluid control device, and vaporization system

Abstract

To diagnose the state of deterioration, etc. of a piezoelectric element without applying a high voltage to the piezoelectric element.SOLUTION: A piezoelectric element diagnosis device 10 diagnoses a piezoelectric element 321 incorporated in a device, and comprises a voltage change information detection unit 12 for detecting voltage change information when the voltage of the piezoelectric element 321 increases or decreases, and a state determination unit 13 for determining the state of the piezoelectric element 321 on the basis of the voltage change information detected by the voltage change information detection unit 12.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a piezoelectric element diagnostic device, a piezoelectric element diagnostic method, and a piezoelectric element diagnostic program. The present invention also relates to a fluid control device using the piezoelectric element diagnostic device, and a vaporization system using the piezoelectric element diagnostic device. [Background technology]

[0002] Piezo valves using a piezoelectric element are used as fluid control valves for mass flow controllers (MFCs) etc. In this type of piezo valve, the valve body is driven relative to the valve seat by applying a voltage to the piezoelectric element to expand and contract the element.

[0003] This piezoelectric element deteriorates over time and breaks down. In particular, since the degree of deterioration differs depending on the magnitude of the applied voltage, the environmental temperature in which it is used, and other factors, it is difficult to predict when the element will break down.

[0004] Here, a deterioration detection circuit has been devised that utilizes the fact that the resistance value of a piezoelectric element decreases as the element deteriorates, as shown in Patent Document 1. This deterioration detection circuit connects a fixed resistor in series to the piezoelectric element, measures the partial voltage across this fixed resistor, and calculates the partial voltage across the piezoelectric element from the measured partial voltage to obtain the resistance value of the piezoelectric element (see the following formula).

[0005] Resistance value R of the piezoelectric element P : R P =(V0-V1) / (V1 / R) Here, V0 is the power supply voltage, V1 is the divided voltage across the fixed resistor (measured voltage), and R is the resistance value of the fixed resistor.

[0006] However, if spike noise is included in the measured voltage, there is a risk that deterioration of the piezoelectric element cannot be detected with high accuracy. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2020 / 218226 Summary of the Invention [Problem to be solved by the invention]

[0008] On the other hand, a piezoelectric element has not only a resistance component (R) but also a capacitance component (C), and the equivalent circuit of a piezoelectric element can be expressed as a parallel circuit of a resistance component and a capacitance component (RC parallel circuit). Furthermore, due to the transient phenomenon of the RC parallel circuit, the rise time and fall time are determined by the product of the resistance component (R) and the capacitance component (C).

[0009] Therefore, the present invention has been made by focusing on the rise time and fall time in the transient phenomenon of an RC parallel circuit, and has an objective of diagnosing the condition of a piezoelectric element, such as its deterioration, without being affected by spike noise, etc. [Means for solving the problem]

[0010] In other words, the piezoelectric element diagnostic device of the present invention is a piezoelectric element diagnostic device that diagnoses a piezoelectric element, and is characterized in that it includes a voltage change information detection unit that detects voltage change information when the voltage of the piezoelectric element rises or falls, and a state determination unit that determines the state of the piezoelectric element based on the voltage change information detected by the voltage change information detection unit.

[0011] Such a piezoelectric element diagnostic device determines the state of the piezoelectric element based on voltage change information when the voltage of the piezoelectric element rises or falls, so that the state of the piezoelectric element can be diagnosed without being affected by spike noise, etc.

[0012] It is preferable that the voltage change information detection section detects a rise time when the voltage of the piezoelectric element rises or a fall time when the voltage of the piezoelectric element falls. With this configuration, it is only necessary to detect the rise time or fall time as the voltage change information, so that the configuration for detecting the voltage change information can be simplified.

[0013] As a specific embodiment for detecting the rise time or fall time, it is desirable that the voltage change information detection unit detects the rise time until the rising threshold voltage is reached when the voltage applied to the piezoelectric element is increased, or detects the fall time until the falling threshold voltage is reached when the voltage applied to the piezoelectric element is decreased.

[0014] In order to be able to objectively diagnose the state of the piezoelectric element, it is desirable for the state determining unit to determine the state of the piezoelectric element by comparing the voltage change information with a threshold value.

[0015] The state determination unit uses two or more threshold values ​​different from each other as the threshold value. With this configuration, by using a plurality of threshold values, the state of the piezoelectric element, such as deterioration, can be classified into a plurality of categories, and the state of the piezoelectric element can be diagnosed more accurately.

[0016] It is preferable that the piezoelectric element diagnostic device of the present invention further comprises a capacitor connected in series with the piezoelectric element. With this configuration, it is possible to adjust the speed at which the voltage change information changes when the voltage of the piezoelectric element increases, and it is possible to accurately and easily detect the state change information.

[0017] It is preferable that the piezoelectric element diagnostic device of the present invention further comprises a fixed resistor connected in parallel with the piezoelectric element. With this configuration, it is possible to adjust the speed at which the voltage change information changes when the voltage of the piezoelectric element drops, and it is possible to accurately and easily detect the state change information.

[0018] It is preferable that the piezoelectric element diagnostic device of the present invention further comprises a detection power supply circuit that applies a test voltage to the piezoelectric element in order to detect the voltage change information. Here, in order to increase or decrease the voltage of the piezoelectric element, it is possible to use a driving power supply circuit that applies a driving voltage to the piezoelectric element. However, the driving power supply circuit is configured to apply a high voltage such as a driving voltage, and in order to configure it to inspect a piezoelectric element incorporated in an existing device, it is necessary to improve or change the driving power supply circuit. On the other hand, if the piezoelectric element diagnostic device is configured to have a detection power supply circuit, it is only necessary to attach it externally to the existing device without improving it.

[0019] It is preferable that the piezoelectric element diagnostic device of the present invention further comprises an inrush current reducing section provided in the detection power supply circuit, which reduces an inrush current generated when voltage application starts. This configuration can prevent the piezoelectric element from being damaged by the inrush current that occurs when the voltage application starts. It can also prevent the capacitance component of the piezoelectric element from being charged more than necessary, and prevent the discharge from taking more time than necessary.

[0020] It is desirable that the detection power supply circuit be housed in a common housing together with a drive power supply circuit that applies a drive voltage to the piezoelectric element. With this configuration, the wiring configuration of the drive power supply circuit and the detection power supply circuit can be simplified. In this case, it is conceivable to provide a switching mechanism in a common housing that switches the power supply circuit connected to the piezoelectric element between the detection power supply circuit and the drive power supply circuit that applies a drive voltage to the piezoelectric element.

[0021] It is desirable that the detection power supply circuit be housed in a housing separate from a housing that houses a drive power supply circuit that applies a drive voltage to the piezoelectric element. With this configuration, the detection power supply circuit can be externally attached to an existing device incorporating a piezoelectric element. The housing housing the drive power supply circuit and the housing housing the detection power supply circuit may be provided with connection ports for connecting them to each other. Also, a switching mechanism may be provided in the housing housing the detection power supply circuit to switch the power supply circuit connected to the piezoelectric element between the detection power supply circuit and the drive power supply circuit that applies a drive voltage to the piezoelectric element.

[0022] In addition, the piezoelectric element diagnosis method of the present invention is a piezoelectric element diagnosis method for diagnosing a piezoelectric element, which is characterized in that it detects voltage change information when the voltage of the piezoelectric element rises or falls, and judges the state of the piezoelectric element based on the detected voltage change information.

[0023] Furthermore, the piezoelectric element diagnosis program of the present invention is a piezoelectric element diagnosis program for diagnosing a piezoelectric element, and is characterized in that it has a function as a voltage change information detection unit that detects voltage change information when the voltage of the piezoelectric element rises or falls, and a function as a state judgment unit that judges the state of the piezoelectric element based on the voltage change information detected by the voltage change information detection unit.

[0024] The piezoelectric element diagnostic program may be distributed electronically, or may be recorded on a program recording medium such as a CD, a DVD, or a flash memory.

[0025] Furthermore, the fluid control device according to the present invention is characterized in that it comprises a piezoelectric valve in which a valve body is driven relative to a valve seat by a piezoelectric element, a valve control unit that controls the opening degree of the piezoelectric valve, and the above-mentioned piezoelectric element diagnosis device.

[0026] In addition, the vaporization system according to the present invention is characterized by comprising a vaporization unit that vaporizes a liquid raw material, a fluid control device that controls the flow rate of the gas vaporized by the vaporization unit, and the above-mentioned piezoelectric element diagnostic device. Effect of the Invention

[0027] In this way, according to the present invention, it is possible to diagnose the state of deterioration of a piezoelectric element without being affected by spike noise or the like. [Brief description of the drawings]

[0028] [Figure 1] 1 is a diagram illustrating a schematic configuration of an evaporation system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a functional block diagram of the control device according to the embodiment. [Diagram 3] 2 is a diagram showing a schematic configuration of a piezoelectric element diagnostic device according to the embodiment; FIG. [Figure 4] FIG. 13 is a diagram showing a method of diagnosing a condition using fall time in the embodiment. [Diagram 5] FIG. 13 illustrates a method of diagnosing a condition using rise time in the embodiment. [Figure 6] FIG. 13 is a diagram illustrating a configuration of a piezoelectric element diagnosis device according to a modified embodiment. [Figure 7] FIG. 13 is a diagram illustrating a configuration of a piezoelectric element diagnosis device according to a modified embodiment. [Figure 8] FIG. 13 is a diagram illustrating a configuration of a piezoelectric element diagnosis device according to a modified embodiment. [Figure 9] FIG. 13 is a diagram showing a modified example of a voltage measurement point. [Figure 10] FIG. 13A shows a configuration in which a detection power supply circuit and a drive power supply circuit are housed in a common housing, and FIG. 13B shows a configuration in which a detection power supply circuit and a drive power supply circuit are housed in separate housings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] <One embodiment of the present invention> An embodiment of a vaporization system incorporating a piezoelectric element diagnostic device according to the present invention will be described below with reference to the drawings. Note that in all of the drawings shown below, for ease of understanding, some parts are omitted or exaggerated as appropriate. The same components are given the same reference numerals and their explanations are omitted as appropriate.

[0030] <1. Basic configuration of vaporization system 100> The vaporization system 100 of this embodiment is incorporated in, for example, a semiconductor manufacturing line, and is intended to supply a predetermined flow rate of gas to a chamber in which a semiconductor manufacturing process is carried out.

[0031] Specifically, as shown in FIG. 1, the vaporization system 100 includes a vaporization unit 2 that vaporizes a liquid material, a mass flow controller 3 that controls the flow rate of the gas (hereinafter, material gas) vaporized by the vaporization unit 2, and a control device 4 that controls the operation of the vaporization unit 2, the mass flow controller 3, etc.

[0032] The vaporization section 2 includes a vaporizer 21 that vaporizes the liquid material by, for example, a baking method, a supply amount control device 22 that controls the amount of liquid material supplied to the vaporizer 21, and a preheater 23 that preheats the liquid material supplied to the vaporizer 21 to a predetermined temperature. The vaporizer 21, the supply amount control device 22, and the preheater 23 are attached to a main body block 5 having a flow path formed therein. The vaporization section 2 may be configured without the preheater 23.

[0033] Vaporizer 21 has storage container 211 for storing liquid material therein, and vaporization heater 212 provided in storage container 211 for vaporizing the liquid material. Storage container 211 is provided with liquid level sensor 213 for detecting the amount of stored liquid material. Note that various types of liquid level sensor 213 can be used, such as a self-heating type, a liquid temperature measurement type, a magnetic type, a capacitance type, and an ultrasonic type.

[0034] The supply amount control device 22 is an electromagnetic on-off valve. This electromagnetic on-off valve 22 is configured to open or close a flow path formed in the main body block 5 to supply or stop the supply of the liquid material to the vaporizer 21. Note that the supply amount control device 22 may be, for example, a control valve such as a piezo valve, a mass flow controller, or the like.

[0035] The preheater 23 has a preheating block 231 in which a flow path through which the liquid material flows is formed, and a preheater 232 provided in the preheating block 231 for preheating the liquid material. The preheater 23 heats the liquid material to a temperature just before vaporization (lower than the boiling point).

[0036] With the vaporizer 2 configured as described above, the liquid material introduced from the liquid material introduction port P1 of the main body block 5 flows through the flow path of the preheating block 231 of the preheater 23 and is preheated. The liquid material preheated by the preheater 23 is introduced into the vaporizer 21 by controlling the electromagnetic on-off valve 22. The liquid material is constantly stored in the vaporizer 21, and the liquid material is vaporized to continuously generate the material gas, which is continuously led to the mass flow controller 3.

[0037] Next, the mass flow controller 3 will be described. The mass flow controller 3 is provided downstream of the vaporizer 2 and controls the flow rate of the material gas generated by the vaporizer 2. Specifically, the mass flow controller 3 includes a fluid detection device 31 that detects the material gas flowing through the flow path, and a piezoelectric valve 32 that controls the flow rate of the material gas flowing through the flow path.

[0038] The fluid detection device 31 and the piezoelectric valve 32 are attached to the main body block 5. Specifically, the fluid detection device 31 and the piezoelectric valve 32 are attached to the main body block 5 on the downstream side of the vaporizer 2. The main body block 5 is installed in a semiconductor manufacturing line or the like with its longitudinal direction facing up and down (vertical direction) so that the liquid material inlet port P1 is located on the lower side and the material gas outlet port P2 is located on the upper side.

[0039] The fluid detection device 31 is, for example, a first pressure sensor 311 of a capacitance type that detects the pressure upstream of a fluid resistor (not shown) provided in the flow path of the main body block 5, and a second pressure sensor 312 of a capacitance type that detects the pressure downstream of the fluid resistor. Note that the fluid detection device 31 in this embodiment constitutes a differential pressure type flow sensor, but may also constitute a thermal type flow sensor using a pair of heating resistors.

[0040] The piezo valve 32 controls the flow rate of the material gas flowing through the flow path of the main body block 5. In this piezo valve 32, a valve body is driven relative to a valve seat by a piezo element 321. The piezo valve 32 in this embodiment is of a so-called normally open type (normally open type), but may be of a normally closed type (normally closed type). In addition, the piezo valve 32 has a drive voltage V applied to the piezo element 321 to drive the piezo valve 32. O The power supply circuit 322 applies a

[0041] Next, the control device 4 will be described. The control device 4 is configured to control the operation of the vaporizer 2, the mass flow controller 3, etc., so as to supply a predetermined flow rate of gas to the chamber.

[0042] Specifically, the control device 4 is a computer having a CPU, memory, AD / DA converter, input means, etc., and the CPU and its peripheral devices work together in accordance with a program stored in the memory to have functions as a set flow rate receiving unit 4a, a flow rate calculating unit 4b, a valve control unit 4c, etc., as shown in Fig. 2. In addition, the control device 4 controls the electromagnetic on-off valve 22 based on a detection signal from the liquid level sensor 213.

[0043] The set flow rate receiving unit 4a receives a set flow rate signal indicating a set flow rate input by a user via an input means such as a keyboard or transmitted from another device.

[0044] The flow rate calculation unit 4b acquires an output signal from the fluid detection device 31 and calculates the flow rate of the material gas output from the vaporization unit 2. The flow rate calculation unit 4b may be provided in the mass flow controller 3 and may constitute a flow rate sensor together with the fluid detection device 31.

[0045] The valve control unit 4c controls the piezo valve 32 based on the set flow rate and the measured flow rate calculated by the flow rate calculation unit 4b, and here outputs a drive signal to a driving power supply circuit 322 of the piezo valve 32 to feedback control the valve opening so that the measured flow rate becomes the set flow rate.

[0046] <2. Piezo element diagnostic function> Thus, the vaporization system 100 of this embodiment has a piezoelectric element diagnostic device 10 that diagnoses the piezoelectric element 321 incorporated in the piezoelectric valve 32.

[0047] The piezoelectric element diagnostic device 10 diagnoses the piezoelectric element 321 by determining the state of the piezoelectric element 321. In this embodiment, "diagnosis of the piezoelectric element 321" includes determining the state of the piezoelectric element 321. Specifically, the piezoelectric element diagnostic device 10 applies a test voltage V to the piezoelectric element 321 as shown in FIG. C a voltage change information detection unit 12 that detects voltage change information when the voltage of the piezoelectric element 321 rises or falls, and a state determination unit 13 that determines the state of the piezoelectric element 321 based on the voltage change information detected by the voltage change information detection unit 12.

[0048] The detection power supply circuit 11 supplies a test voltage V to the piezoelectric element 321 in order to diagnose the piezoelectric element 321. C Specifically, the detection power supply circuit 11 applies the inspection voltage V C and a DC power supply 11a for applying an inspection voltage V C The DC power supply 11a may have the function of the switch S1.

[0049] Here, the inspection voltage V of the detection power supply circuit 11 C is the driving voltage V for driving the piezo valve 32. O This voltage is smaller than the driving voltage V for fully closing the piezo valve 32, and is a voltage that will not drive the piezo valve 32 even if it is applied to the piezo element 321. O is, for example, 120V.

[0050] When the switch S1 of the detection power supply circuit 11 is closed, the inspection voltage V C is applied, and the voltage rises as charge accumulates in the capacitance component of the piezoelectric element 321. On the other hand, when the switch S1 of the detection power supply circuit 11 is opened, the charge accumulated in the capacitance component of the piezoelectric element 321 is discharged and the voltage drops.

[0051] The voltage change information detector 12 detects the rise time when the voltage of the piezoelectric element 321 rises or the fall time when the voltage of the piezoelectric element 321 falls.

[0052] Specifically, when the voltage applied to the piezoelectric element 321 is increased, the voltage change information detection unit 12 detects the rising threshold voltage V U_TH The rise time T U When the voltage applied to the piezoelectric element 321 is decreased, the lower threshold voltage V D_TH The time it takes to fall to reach T D Detect.

[0053] The voltage change information detection unit 12 of this embodiment directly or indirectly detects the voltage change of the piezoelectric element 321, and includes a voltage measurement unit 12a that measures the voltage between the input terminals (positive electrode and negative electrode) of the piezoelectric element 321, and a voltage measurement unit 12b that measures the rise time T U Or fall time T D and a time calculation unit 12b for calculating the time.

[0054] The time calculation unit 12b calculates the fall time T D When calculating As shown in FIG. 4, the time calculation unit 12b calculates the inspection voltage V C In the transient state immediately after the application of the test voltage V C from the lower threshold voltage V D_TH The time it takes to reach this point is the fall time T D Specifically, the time calculation unit 12b detects the inspection voltage V C From the specified time when the test voltage V C The application of is stopped and the threshold voltage V D_TH The time it takes to reach this point is the fall time T D Detect as.

[0055] In addition, the time calculation unit 12b calculates the inspection voltage V C The threshold voltage V D_TH The time it takes to reach this point is the fall time T D In addition, the time calculation unit 12b may detect the inspection voltage V C The time when the voltage drops by a certain amount from the threshold voltage V D_TH The time it takes to reach this point is the fall time T D It may be detected as

[0056] The time calculation unit 12b calculates the rise time T U When calculating As shown in FIG. 5, the time calculation unit 12b calculates the inspection voltage V C In the transient state immediately after the application of the test voltage V C The threshold voltage V rises from the voltage before the application (for example, 0 V). U_TH (Here, the test voltage V C ) is the rise time T U Specifically, the time calculation unit 12b detects the inspection voltage V C From a specified time when the test voltage V C Start applying the rising threshold voltage V U_TH The time it takes to reach this point is the rise time T U Detect as.

[0057] In addition, the time calculation unit 12b calculates the inspection voltage V CThe rising threshold voltage V U_TH The time it takes to reach this point is the rise time T U In addition, the time calculation unit 12b may detect the inspection voltage V C The rising threshold voltage V U_TH The time it takes to reach this point is the rise time T U It may be detected as

[0058] The state determination unit 13 determines the state of the piezoelectric element 321 by comparing the voltage change information detected by the voltage change information detection unit 12 with a threshold value. Here, the threshold value can be set by calculating in advance the discharge time / charge time of the deteriorated piezoelectric element 321 through an experiment, a simulation, or the like. When multiple threshold values ​​are used, the discharge time / charge time of multiple piezoelectric elements 321 in different deteriorated states can be set by calculating in advance through an experiment, a simulation, or the like.

[0059] Specifically, the state determination unit 13 calculates the rise time T U Or fall time T D and a preset threshold time T U_TH , T D_TH Compared with the rise time T U Or fall time T D and the threshold time T U_TH , T D_TH Based on the result of the comparison with the threshold time T U_TH , T D_TH By setting the threshold, it is possible to determine whether the equipment is in a condition that requires immediate replacement, whether the equipment is about halfway to failure, or whether the equipment is in a condition that can be used normally for a specified period of time.

[0060] For example, the fall time T D When using the time calculation unit 12b, the state determination unit 13 calculates the fall time T D and a preset threshold time T D_TH Compared with the fall time TD is the threshold time T D_TH If the measured value falls below this value, it is determined that the piezoelectric element 321 is in a deteriorated state.

[0061] In addition, the rise time T U When using the time calculation unit 12b, the state determination unit 13 calculates the rise time T U and a preset threshold time T U_TH Compared with the rise time T U is the threshold time T U_TH If the measured value falls below this value, it is determined that the piezoelectric element 321 is in a deteriorated state.

[0062] Furthermore, the state determination unit 13 can also output an alarm or an error based on the determination result. Here, the state determination unit 13 may be configured to output a signal to control an alarm device that emits sound or light, or to display an alarm or an error on a display of a user terminal or the like. Alternatively, it may be configured to output a voltage signal to a user-side device (e.g., a user terminal or a process control device, etc.) so that the user can make a determination on the user side. Furthermore, the state detection unit 13 may be configured to convert the voltage (voltage value corresponding to the number of seconds) acquired by the voltage measurement unit 12a and output it as an analog signal. Even with such a configuration, the user can determine the deterioration.

[0063] <3. Piezo element diagnostic method> Next, a piezoelectric element diagnosis method using the piezoelectric element diagnosis device 10 of this embodiment will be described.

[0064] The piezoelectric diagnosis method of the present embodiment is performed during a period when the piezoelectric valve 32 is not driven. The period when the piezoelectric valve 32 is not driven is, for example, a period when the vaporization system 100 is stopped or a period when the driving voltage V O The period is when no voltage is applied.

[0065] ·Descent time T D When diagnosing using During the period when the piezo valve 32 is not driven, the switch S1 of the detection power supply circuit 11 is closed to apply a predetermined inspection voltage V to the piezo element 321. C The test voltage V C The application time of the test voltage is a preset fixed value.

[0066] After that, the switch S1 of the detection power supply circuit 11 is opened to supply the inspection voltage V C Then, the voltage change information detection unit 12 detects whether the voltage (measured voltage) of the piezoelectric element 321 measured by the voltage measurement unit 12a is lower than the falling threshold voltage V D_TH The time it takes to fall to reach T D (See Figure 4.)

[0067] The state determination unit 13 then calculates the fall time T D and a preset threshold time T D_TH Compared with the fall time T D is the falling threshold time T D_TH If it is below this value, it is determined that the piezoelectric element 321 is in a deteriorated state.

[0068] Rise time T U When diagnosing using During the period when the piezo valve 32 is not driven, the switch S1 of the detection power supply circuit 11 is closed to apply a predetermined inspection voltage V to the piezo element 321. C The test voltage V C The application time of the test voltage is a preset fixed value.

[0069] At this time, the voltage change information detection unit 12 detects whether the voltage (measured voltage) of the piezoelectric element 321 measured by the voltage measurement unit 12a is equal to or exceeds the rising threshold voltage V U_TH The rise time T U (See Figure 5.)

[0070] The state determination unit 13 then calculates the rise time TU and a preset threshold time T U_TH Compared with the rise time T U is the rising threshold time T U_TH If it is below this value, it is determined that the piezoelectric element 321 is in a deteriorated state.

[0071] <4. Effects of this embodiment> As described above, according to the vaporization system 100 of this embodiment, the state of the piezoelectric element 321 is determined based on the voltage change information when the voltage of the piezoelectric element 321 rises or falls, so that the state of the piezoelectric element 321 can be diagnosed without being affected by spike noise, etc. As a result, it is possible to prevent the piezoelectric valve 32 from suddenly breaking down, causing flow rate abnormalities in the semiconductor process, and to prevent damage such as film formation abnormalities and wafer lot-out.

[0072] <5. Other embodiments> For example, as shown in Fig. 6, the detection power supply circuit 11 may have an inrush current reduction unit 14. This inrush current reduction unit 14 has a fixed resistor 141 and a switch S2 connected in parallel to the piezoelectric element 321 and the switch S1. In this configuration, when the detection power supply circuit 11 starts applying a voltage, the switch S2 is closed before the switch S1 is closed to allow the inrush current to flow to the fixed resistor 141. Thereafter, the switch S2 is opened and the switch S1 is closed. As a result, the inrush current flows through the fixed resistor 141 of the inrush current reduction unit 14, and the inrush current does not flow through the piezoelectric element 321.

[0073] The state determination unit 13 may use two or more different thresholds as the threshold to be compared with the voltage change information. With this configuration, by using multiple thresholds, the state of the piezoelectric element, such as deterioration, can be classified into multiple categories, and the state of the piezoelectric element can be diagnosed more accurately. For example, a threshold for issuing a warning to the user and a threshold for prompting the user to replace the piezoelectric element (piezo valve) may be used.

[0074] 7, the piezoelectric element diagnostic device 10 may include a capacitor 15 connected in series with the piezoelectric element 321. This capacitor 15 is connected in series with the piezoelectric element 321 in the detection power supply circuit 11. With this configuration, it is possible to adjust (for example, slow down) the speed of change in voltage change information when the voltage of the piezoelectric element 321 increases, and it is possible to accurately and easily detect state change information. Note that a configuration in which the capacitor 15 is connected in parallel with the piezoelectric element 321 is also possible.

[0075] Furthermore, the piezoelectric element diagnostic device 10 may include a resistor 16 connected in parallel to the piezoelectric element 321 as shown in FIG. 7. The resistor 16 is a fixed resistor or a variable resistor, and is connected in parallel to the piezoelectric element 321 in the detection power supply circuit 11. With this configuration, the change speed of the voltage change information when the voltage of the piezoelectric element 321 drops can be adjusted (for example, made faster), and the state change information can be detected accurately and easily. By making the change speed of the voltage change information when the voltage of the piezoelectric element 321 drops faster, the diagnosis time can be shortened. Furthermore, if the resistor 16 is a variable resistor, the change speed (time) of the voltage change information can be changed according to the situation. Note that, in FIG. 7, the circuit configuration includes both the capacitor 15 and the resistor 16, but the circuit configuration may include either the capacitor 15 or the resistor 16. Note that a configuration in which the resistor 16 is connected in parallel to the piezoelectric element 321 is also conceivable. Furthermore, as shown in FIG. 8, the resistor 16 may be connected in parallel to the piezoelectric element 321 and the capacitor 15.

[0076] The voltage measurement location of the voltage measurement unit 12a is not limited to between the input terminals (positive and negative electrodes) of the piezoelectric element 321 as in the above embodiment. Measuring the voltage of only the piezoelectric element 321 as in the above embodiment reduces noise during charging and discharging and improves diagnostic accuracy, but the voltage measurement location of the voltage measurement unit 12a can be various locations as shown in Fig. 9. As shown in (a) to (e) of Fig. 9, the voltage measurement unit 12a may measure the voltage of not only the piezoelectric element 321 but also the capacitor 15 or resistor 16 connected in series or parallel to the piezoelectric element 321.

[0077] 9(f), the voltage measuring unit 12a may be configured to measure the voltage across the resistor 16 connected in series to the piezoelectric element 321. In this case, the measured voltage across the resistor 16 is used to detect a change in the voltage across the resistor 16 over time, which corresponds to the charging time or discharging time of the piezoelectric element 321, and the state of the piezoelectric element 321 can be determined. The measured voltage across the resistor 16 is also used to detect the charging time or discharging time of the piezoelectric element 321, and the state of the piezoelectric element 321 can be determined.

[0078] Furthermore, as shown in FIG. 9(g), the voltage measuring unit 12a may be configured to measure the voltage across the resistor 16 connected in series to the piezoelectric element 321 and the voltage across the piezoelectric element 321. In this case, the resistance value of the piezoelectric element 321 can be detected using the measured voltage across the resistor 16. Also, the measured change in voltage across the piezoelectric element 321 over time (rise time or fall time) is detected. Then, the state of the piezoelectric element is determined from the detected resistance value of the piezoelectric element 321 and the detected change in voltage of the piezoelectric element 321 over time (rise time or fall time). In this way, the state of the piezoelectric element can be determined more accurately by using two determination indexes.

[0079] Moreover, as shown in FIG. 10(a), the detection power supply circuit 11 may be configured to be housed in a common housing B1 (control box B1) together with the driving power supply circuit 322. In this configuration, it is possible to house the switching mechanism 17 in the common housing B1 (control box B1). Here, the driving power supply circuit 322 may be included in the control device 4, and in this case, the control box B1 corresponds to the control device 4. In other words, the control device 4 includes the detection power supply circuit 11. Also, as shown in FIG. 10(b), the detection power supply circuit 11 may be configured to be housed in a second housing B12 (inspection control box B12) separate from the first housing B11 (driving control box B11) that houses the driving power supply circuit 322. In this configuration, it is possible to house the switching mechanism 17 in the second housing B12. Here, the driving power supply circuit 322 may be included in the control device 4, and in this case, the driving control box B11 corresponds to the control device 4. The detection power supply circuit 11 in FIG. 10(b) may have a configuration including a DC power supply 11a, or may be configured to step down the voltage supplied from the drive power supply circuit 322 to produce the inspection voltage V C The voltage step-down circuit may be configured as follows:

[0080] The switching mechanism 17 is configured using open / close switches 17a and 17b. By closing the open / close switch 17a, the driving power supply circuit 322 is connected to the piezoelectric element 321, and by closing the open / close switch 17b, the detection power supply circuit 11 is connected to the piezoelectric element 321. During a period when the piezo valve 32 is not driven, such as when the vaporization system 100 is stopped, the power supply circuit connected to the piezo element 321 is switched by the switching mechanism 17. Specifically, the power supply circuit connected to the piezo element 321 is switched from the driving power supply circuit 322 to the detection power supply circuit 11.

[0081] In the above embodiment, the detection power supply circuit 11 supplies the inspection voltage V C However, the driving voltage V O Alternatively, the piezoelectric element 321 may be diagnosed by detecting information on a change in voltage of the piezoelectric element 321 when the application of the voltage starts or stops.

[0082] The voltage change information detection unit detects the rise time or fall time of the voltage of the piezoelectric element as the voltage change information, but may detect the voltage change rate (differential value of the voltage) or cumulative voltage (integral value of the voltage) of the piezoelectric element. Note that since the voltage change rate and cumulative integral contain noise, detecting the rise time or fall time as in the above embodiment allows for more accurate diagnosis of the piezoelectric element.

[0083] Furthermore, the piezoelectric element diagnostic device may have a life prediction unit that compares the rise time or fall time detected last time with the rise time or fall time detected this time, calculates the slope of the change in the rise time or fall time, and predicts the life of the piezoelectric element 321.

[0084] Moreover, the vaporization method may be other vaporization methods such as a heating method in addition to bubbling.

[0085] In addition, although the vaporizer 2 and the mass flow controller 3 in the above embodiment are configured to be attached to the main body block 5, the main body block 5 may be configured to be separate from each other. Also, the vaporizer 2 and the mass flow controller 3 may be configured to be connected by piping.

[0086] Furthermore, although the vaporization system in the above embodiment supplies the material gas to a chamber of a semiconductor manufacturing apparatus, it may also supply the material gas to other chambers.

[0087] Although the piezoelectric element diagnostic device in the above embodiment is incorporated in the vaporization system, it may be a separate device (module) from the vaporization system. Also, the piezoelectric element diagnostic device may be a separate device (module) from the fluid control device.

[0088] Furthermore, the piezoelectric element diagnostic device may diagnose piezoelectric elements used in applications where they are driven by the application of voltage, as well as piezoelectric elements used in applications where they output voltage when pressure is applied.

[0089] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention. [Explanation of symbols]

[0090] 100···Evaporation system 2. Evaporation section 3. Fluid control device (mass flow controller) 32 Piezo valve 321 Piezo element 322 Drive power supply circuit 10 Piezo element diagnostic device 11 Detection power supply circuit 12 Voltage change information detection section 12a Voltage measurement section 12b Time calculation section 13 Status judgment section 14 Inrush current reduction section 141...Fixed resistance 15 Capacitor 16 Resistance 17 Switching mechanism B1: Common housing B11...1st housing B12...Second housing

Claims

1. A piezoelectric element diagnostic device for diagnosing piezoelectric elements, A voltage change information detection unit that detects voltage change information when the voltage of the piezoelectric element rises or falls, A piezoelectric element diagnostic device comprising: a state determination unit that determines the state of the piezoelectric element based on the voltage change information detected by the voltage change information detection unit.

2. The piezoelectric element diagnostic device according to claim 1, wherein the voltage change information detection unit detects the time it takes for the voltage of the piezoelectric element to rise or the time it takes for the voltage to fall.

3. The voltage change information detection unit is When the voltage applied to the piezoelectric element is increased, the time it takes to reach the rising threshold voltage is detected, or The piezoelectric element diagnostic device according to claim 1, which detects the time it takes to reach a lower threshold voltage when the voltage applied to the piezoelectric element is reduced.

4. The piezoelectric element diagnostic device according to claim 1, wherein the state determination unit determines the state of the piezoelectric element by comparing the voltage change information with a threshold value.

5. The piezoelectric element diagnostic device according to claim 4, wherein the state determination unit uses two or more different threshold values ​​as the threshold values.

6. The piezoelectric element diagnostic device according to claim 1, further comprising a capacitor connected in series with the piezoelectric element.

7. The piezoelectric element diagnostic device according to claim 1, further comprising a fixed resistor connected in parallel with the piezoelectric element.

8. The piezoelectric element diagnostic device according to claim 1, further comprising a detection power supply circuit for applying a test voltage to the piezoelectric element in order to detect the voltage change information.

9. The piezoelectric element diagnostic device according to claim 8, further comprising an inrush current reduction unit provided in the detection power supply circuit for reducing the inrush current that occurs when voltage is first applied.

10. The piezoelectric element diagnostic device according to claim 8, wherein the detection power supply circuit is housed in a common housing with the drive power supply circuit that applies a drive voltage to the piezoelectric element.

11. The piezoelectric element diagnostic device according to claim 8, wherein the detection power supply circuit is housed in a second housing separate from the first housing which houses the drive power supply circuit that applies a drive voltage to the piezoelectric element.

12. A piezoelectric element diagnostic method for diagnosing piezoelectric elements incorporated into a device, The voltage change information is detected when the voltage of the piezoelectric element rises or falls. A piezoelectric element diagnostic method for determining the state of the piezoelectric element based on the detected voltage change information.

13. A piezoelectric element diagnostic program for diagnosing piezoelectric elements incorporated into a device, The function of the voltage change information detection unit is to detect voltage change information when the voltage of the piezoelectric element rises or falls, A piezoelectric element diagnostic program that provides a computer with the function of a state determination unit that determines the state of the piezoelectric element based on the voltage change information detected by the voltage change information detection unit.

14. A piezo valve in which the valve body is driven relative to the valve seat by a piezoelectric element, A valve control unit that controls the opening degree of the piezo valve, A fluid control device comprising a piezoelectric element diagnostic device according to any one of claims 1 to 11.

15. A vaporization unit that vaporizes the liquid raw material, A fluid control device that controls the flow rate of the gas vaporized by the vaporization unit, A vaporization system comprising a piezoelectric element diagnostic device according to any one of claims 1 to 11.

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