Vaporizer, vaporizer control method, vaporizer program, and fluid control device

Abstract

To provide a vaporizer capable of making a statically determinate time shorter than an existing time and sustaining stability in control.SOLUTION: A vaporizer 100 includes a control valve 2 disposed in a channel through which a liquid material flows, a vaporization unit 3 that vaporizes the liquid material through pressure reduction or heating, a liquid flow sensor 1 that measures a flow of the liquid material flowing through the channel, and a valve control unit 41 that controls the control valve 2 through PI or PID control based on a set value represented by a set flow and the measurement value of the flow measured by the liquid flow sensor 1. The vaporizer further includes an integral gain change unit 42 that changes an integral gain, which is set in the valve control unit 41, from a reference integral gain to a correction integral gain, which is different from the reference integral gain, during a transient response period of the flow measured by the liquid flow sensor 1.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a vaporizer in which the flow rate of a liquid material is controlled by PI control or PID control. [Background technology]

[0002] For example, in semiconductor manufacturing processes, vaporizers are used to vaporize liquid material to obtain material gas to be introduced into a vacuum chamber. As shown in Patent Document 1, this vaporizer includes a control valve in which the liquid material and carrier gas are mixed, a vaporizer located downstream of the control valve and vaporizing the liquid material by heating or decompression, a liquid flow sensor located upstream of the control valve and measuring the flow rate of the liquid material, and a valve controller that controls the aperture of the control valve by PID control based on a set value indicated by a set flow rate set by a user and a measurement value measured by the liquid flow sensor.

[0003] In such a vaporizer, when a stepwise set flow rate is set so that the liquid material is maintained at a target constant flow rate from a state where the control valve is fully closed, it may take some time for the measured flow rate measured by the liquid flow sensor to match the final set flow rate. In other words, the offset is not eliminated in a short time, Settling time For example, this may not be completed within the allowable time determined by the requirements of the semiconductor manufacturing process. This problem may also occur when a predetermined flow rate is maintained but changed to a larger set flow rate.

[0004] The inventors of the present application conducted extensive research into why this phenomenon occurs and discovered for the first time that the cause is that the temperature of the control valve drops after the flow rate of the liquid material increases, preventing the required opening from being achieved due to thermal contraction of the metal components of the valve body, valve seat, etc. In other words, when the liquid material vaporizes in the vaporizer adjacent to the control valve, the heat of vaporization cools the control valve. Thermal contraction occurs in the components of the control valve, causing it to maintain a larger opening than the opening that should be achieved by PID control. This results in the phenomenon of the offset remaining.

[0005] In addition, depending on the material of the control valve and the settings of the various heaters, the temperature of the control valve may rise, causing thermal expansion in the metal that makes up the valve body, valve seat, etc., resulting in a smaller opening than required. This may cause an overshoot and then an undershoot, keeping the actual flow rate smaller than the set value, and the offset may continue to remain.

[0006] To eliminate such an offset, it is conceivable to set the integral gain to a value larger than the current value, but it is difficult to simply increase the value of the integral gain in this type of vaporizer. Settling time Furthermore, there are strict restrictions on the rise time and the amount of overshoot, so a high gain that is already close to the limit is set. If an even higher integral gain is constantly set for a valve controller of a vaporizer that has already been tuned in this way, hunting will occur in the flow rate of the liquid material due to overshoot during the transient response period when the flow rate rises or unexpected disturbances, and the flow rate control of the liquid material itself may become unstable in the first place. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-156055 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above-mentioned problems, and in particular Settling time The object of the present invention is to provide a vaporizer that can maintain stable control while shortening the time required for the control valve to operate more efficiently than ever before. Settling time The object of the present invention is to provide a fluid control system that can shorten the time required for control while achieving stable control. [Means for solving the problem]

[0009] That is, the vaporization device of the present invention is a vaporization device comprising a control valve provided in a flow path through which a liquid material flows, a vaporization section in which the liquid material is vaporized by reducing pressure or heating, a liquid flow sensor that measures the flow rate of the liquid material flowing through the flow path, and a valve controller that controls the control valve by PI control or PID control based on a set value indicated by a set flow rate and the measured value of the flow rate measured by the liquid flow sensor, and is characterized in that it further comprises an integral gain switching section that switches the integral gain set in the valve controller from a reference integral gain to a correction integral gain different from the reference integral gain during a transient response period of the flow rate measured by the liquid flow sensor.

[0010] In addition, the control method for a vaporization device of the present invention is a control method for a vaporization device equipped with a control valve provided in a flow path through which a liquid material flows, a vaporization section in which the liquid material is vaporized by reducing pressure or heating, and a liquid flow sensor that measures the flow rate of the liquid material flowing through the flow path, and is characterized by including: controlling the control valve by PI control or PID control based on a set value indicated by a set flow rate and a measured value of the flow rate measured by the liquid flow sensor; and switching the integral gain set in the valve controller from a reference integral gain to a correction integral gain different from the reference integral gain during a transient response period of the flow rate measured by the liquid flow sensor.

[0011] In this way, the integral gain set in the valve controller is switched from the reference integral gain to the corrected integral gain during the transient response period of the flow rate measured by the liquid flow sensor, so that even if the amount of vaporization of the liquid material in the vaporizer increases, the temperature of the control valve decreases accordingly, causing an increase in opening due to thermal contraction and making it difficult to eliminate the offset, it is possible to cancel out this effect. Similarly, depending on the combination of the characteristics of the material of the control valve and the amount of heat in the vaporizer, the temperature of the control valve may rise, causing a decrease in opening due to thermal expansion and making it difficult to eliminate the offset, but the present invention makes it possible to cancel out such effects. Therefore, the time required for the set value and the measured value to almost match is Settling time Furthermore, since the reference integral gain is set at the beginning of the transient response period of the flow rate when no temperature drop occurs, and the correction integral gain can be set only when a temperature drop occurs, it is possible to reduce the amount of overshoot and shorten the time required to eliminate the offset, while also achieving control stability.

[0012] In order to reduce the offset that occurs when the opening of the control valve increases due to a temperature drop, the correction integral gain should be set to a value higher than the reference integral gain.

[0013] In order to increase the stability of control by using an integral gain suitable for when the control valve is operating at a temperature in normal use, for example, the reference integral gain is set to a value that is the ratio of the flow rate response when the vaporizer is not present. Settling time It is sufficient if the value is set so that the time is within a predetermined allowable time.

[0014] In order to set the corrective integral gain appropriate for when a temperature drop occurs in the control valve based on the reference integral gain, the corrective integral gain is set to a value that is indicative of a flow rate response when the vaporizing unit is present and when switching from the reference integral gain to the corrective integral gain during the transient response period. Settling time It is sufficient if the value is determined so that the time is within the allowable time.

[0015] After the offset is eliminated, in order to increase the resistance to disturbances and make it difficult for the measured value to deviate from the set value, and to further increase the stability of the control, the integral gain switching unit convergence After that, the integral gain set in the valve controller may be returned from the correction integral gain to the reference integral gain.

[0016] In order to be able to switch from the reference integral gain to the corrective integral gain at an appropriate timing that allows the offset to be eliminated in a short time using a simple algorithm, the integral gain switching unit should switch the integral gain set in the valve controller from the reference integral gain to the corrective integral gain after a predetermined time has elapsed based on the point at which the set flow rate starts to rise.

[0017] For example, the rise time and Settling time To shorten the time required for switching from the base integral gain to the corrected integral gain while reducing the amount of overshoot and preventing hunting or the like from occurring in the flow rate, the timing for switching from the base integral gain to the corrected integral gain should be set within the period from the start of the rise of the flow rate response to the peak point when the control valve is continuously controlled with the base integral gain fixed. Here, the peak point may not only be the point at which the flow rate value is at its maximum, but also include a nearby section based on the point at which the flow rate value is at its maximum. For example, the nearby section corresponds to a section in which the amount of overshoot is sufficiently reduced and hunting or the like does not occur, even if it is shifted by a predetermined small time from the point at which the flow rate value is at its maximum.

[0018] In order to be able to switch from the reference integral gain to the corrective integral gain of a more appropriate value taking into account the effects of the amount of temperature drop and the rate of temperature drop in the control valve, the integral gain switching unit may be configured to set the timing for switching from the reference integral gain to the corrective integral gain according to the magnitude of the set value indicated by the set flow rate or the type of liquid material.

[0019] It is preferable that the vaporizer further includes a correction integral gain change unit that changes the correction integral gain. In this case, the correction integral gain change unit changes the correction integral gain, and the integral gain switching unit can switch to a correction integral gain that takes into account the temperature drop of the control valve, thereby shortening the time it takes to eliminate the offset.

[0020] The correction integral gain change unit changes the correction integral gain based on at least one of the type of liquid material, the set flow rate of the liquid material, the set pressure of the liquid material, the set flow rate of the carrier gas, the pressure upstream of the control valve, the pressure downstream of the control valve, the set temperature of the control valve, the set temperature of the vaporization unit, or the ambient temperature. In such a case, the correction integral gain change unit changes the correction integral gain based on parameters related to the type of liquid material, the set flow rate of the liquid material, the set pressure of the liquid material, the set flow rate of the carrier gas, the pressure upstream of the control valve, the pressure downstream of the control valve, the set temperature of the control valve, the set temperature of the vaporization unit, or the ambient temperature, and the temperature drop of the control valve, so that the correction integral gain can be changed to one that takes into account the effect of the temperature drop of the control valve.

[0021] In order to increase the vaporization efficiency of the liquid material in the vaporizing unit, the control valve may include a liquid inlet port through which the liquid material is introduced, a gas inlet port through which the carrier gas is introduced, and an outlet port through which a gas-liquid mixture of the liquid material and the carrier gas is discharged to the outside. In this embodiment, the amount and rate of temperature decrease in the control valve are increased, and therefore the effect of improving the control characteristics by switching the integral gain of the present invention is more pronounced.

[0022] A specific example of a configuration in which a large temperature drop is likely to occur in the control valve during control and switching the integral gain can be expected to significantly improve control characteristics compared to conventional configurations is one in which the control valve and the vaporization section are located adjacent to each other.

[0023] To achieve substantially the same effects as the vaporizer of the present invention by updating a program in an existing vaporizer, the vaporizer includes a control valve provided in a flow path through which a liquid material flows, a vaporizer that vaporizes the liquid material by reducing pressure or heating, and a liquid flow sensor that measures the flow rate of the liquid material through the flow path. The control program includes a valve controller that controls the control valve by PI or PID control based on a set value indicating a set flow rate and a flow rate measured by the liquid flow sensor, and an integral gain switching unit that switches the integral gain set in the valve controller from a reference integral gain to a correction integral gain different from the reference integral gain during a transient response period of the flow rate measured by the liquid flow sensor. The vaporizer program may be distributed electronically or recorded on a program recording medium such as a CD, DVD, or flash memory.

[0024] A fluid control device comprising: a control valve provided in a flow path through which a fluid flows; and a valve controller that controls the control valve by PI control or PID control using a set value of a flow rate or pressure indicated by a target command and a measurement value measured by the fluid sensor, wherein the control valve is provided in an operating environment in which a temperature change of a predetermined value or more occurs after a rise in the measurement value measured by the fluid sensor during control by the valve controller; and the fluid control device further comprises an integral gain switching unit that switches the integral gain set in the valve controller from a reference integral gain to a correction integral gain different from the reference integral gain during a transient response period of the measurement value measured by the fluid sensor. In this fluid control device, even if, for example, a low-temperature fluid flows into the control valve that is kept at a high temperature and the temperature of the control valve drops significantly, Settling time Conversely, even if a high-temperature fluid flows into the control valve and the temperature of the control valve rises significantly, the same can be achieved. Settling time This allows the time to be reduced while also achieving control stability. [Effects of the Invention]

[0025] As described above, the vaporization device according to the present invention is configured to switch from the reference integral gain to the corrected integral gain during a transient response period of the flow rate. Therefore, if PID control is performed on the control valve with the reference integral gain fixed, an offset will not be eliminated due to a drop in the temperature of the control valve itself. Settling time In addition, since the corrective integral gain can be applied when the temperature of the control valve drops and the opening is likely to increase, it is possible to prevent hunting from occurring by setting a high gain, and to achieve control stability. Similarly, even when the flow rate is maintained at a value smaller than the set value due to a temperature rise in the control valve itself, the offset can be similarly eliminated, Settling time It is possible to shorten the [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram showing the configuration of a vaporization device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing details of a vaporizer in the first embodiment. [Figure 3] FIG. 2 is a functional block diagram showing the configuration of a control mechanism in the first embodiment. [Figure 4] FIG. 4 is an image diagram showing the timing of switching integral gains in the first embodiment. [Figure 5] 6 is a graph showing the change in valve temperature when the flow rate of the liquid material rises, and the step response of the vaporizer of the first embodiment at the first setting and the step response of a conventional vaporizer. [Figure 6] FIG. 6 is an enlarged view of the peak portion in FIG. 5 showing the timing of switching integral gain and the convergence state of flow rate. [Figure 7] 6 is a graph showing the change in valve temperature when the flow rate of the liquid material rises, and the step response of the vaporizer of the first embodiment at the second setting and the step response of a conventional vaporizer. [Figure 8] FIG. 8 is an enlarged view of the peak portion in FIG. 7 showing the timing of switching the integral gain and the convergence state of the flow rate. [Figure 9] FIG. 4 is a schematic diagram showing a modified example of the vaporizer according to the first embodiment of the present invention. [Figure 10] FIG. 4 is a schematic diagram showing a modified example of the control mechanism in the first embodiment of the present invention. [Figure 11] FIG. 4 is a schematic diagram showing the configuration of a fluid control device according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a functional block diagram showing the configuration of a control mechanism in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] A vaporizer 100 according to a first embodiment of the present invention will be described with reference to FIGS.

[0028] The vaporizer 100 of the first embodiment is used in, for example, a semiconductor manufacturing process, and vaporizes a liquid material (raw material liquid) to generate a material gas (raw material gas) to be supplied into a chamber.

[0029] 1, this vaporization device 100 includes a liquid material line L1 through which the liquid material flows, a carrier gas line L2 through which a carrier gas flows, an outlet line L3 through which a mixed gas of the carrier gas and the material gas obtained by vaporizing the liquid material is discharged, and a control mechanism 4 that controls the devices provided on each line. Here, the terminal ends of the liquid material line L1 and the carrier gas line L2 are each connected to the inlet side of a vaporizer VP in which the liquid material is vaporized, and the tip of the outlet line L3 is connected to the outlet side of the vaporizer VP.

[0030] The liquid material line L1 includes a tank TN in which the liquid material is stored, and a liquid flow sensor 1 that is provided on a flow path connecting the tank TN and the vaporizer VP and that measures the flow rate of the liquid material.

[0031] A pressurized gas introduction pipe that introduces pressurized gas for pressurizing the liquid material into the gas phase in the tank TN, and a liquid discharge pipe whose tip is immersed in the liquid material in the tank TN and forms a liquid material line L1 are inserted into the tank TN.

[0032] The liquid flow sensor 1 is, for example, a pressure-type flow sensor that includes a laminar flow element (not shown), an upstream pressure sensor provided upstream of the laminar flow element, a downstream pressure sensor provided downstream of the laminar flow element, and a flow rate calculation board that calculates the flow rate of the liquid based on the outputs of the pressure sensors. For example, the liquid flow sensor 1 calculates the flow rate of the liquid material flowing through the liquid material line L1 based on the differential pressure of the laminar flow element or the difference between the squares of the pressures, and outputs the calculated value to the control mechanism 4.

[0033] Carrier gas line L2 is provided with a mass flow controller MFC that controls the flow rate of carrier gas such as nitrogen flowing into vaporizer VP. The mass flow controller MFC is a packaged unit that includes a valve, flow sensor, and control board (not shown), and the valve opening is controlled by feedback control based on the deviation between the set flow rate and the flow rate measured by the flow sensor.

[0034] As shown in the schematic diagram of FIG. 2, the vaporizer VP includes a control valve 2 and a vaporizing section 3 provided adjacent to the downstream side of the control valve 2.

[0035] The control valve 2 includes a metal body 21 having a flow path formed therein and a valve seat 23 formed on its upper surface, a metal diaphragm structure 22 provided on the upper surface of the body 21 and equipped with a diaphragm 221 that functions as a valve element 24 that moves in contact with and away from the valve seat 23, and a piezoelectric actuator 25 that is an actuator for driving the diaphragm 221. The piezoelectric actuator 25 adjusts the degree of opening between the valve seat 23 and the valve element 24, thereby controlling the flow rate of the liquid material in the first embodiment. Furthermore, because the body 21 and the diaphragm structure 22 are made of metal, a decrease in temperature causes thermal contraction, increasing the distance between the valve seat 23 and the valve element 24. Conversely, a rise in temperature causes thermal expansion, decreasing the distance between the valve seat 23 and the valve element 24. Therefore, even if the same voltage is applied to the piezoelectric actuator 25, the degree of opening may vary depending on the temperature.

[0036] A liquid inlet port P1, through which liquid material is introduced into the body 21 from the liquid material line L1, and a gas inlet port P2, through which carrier gas is introduced into the interior from the carrier gas line L2, are formed on the side of the body 21 of the control valve 2. The liquid material and carrier gas introduced into the body 21 pass through an internal flow path and flow into a gas-liquid mixing section, which is the space formed between the top surface of the body 21 and the diaphragm structure 22, where they are mixed. The gas-liquid mixture, which is a mixture of the liquid material and the carrier gas, passes through the internal flow path and is discharged to the outside from a liquid outlet port P3 that opens on the side of the body 21. In the first embodiment, the outlet port of the control valve 2 is connected to the inlet of the vaporization section 3 adjacent to the downstream stage.

[0037] Furthermore, a valve heater 26 is built into the body 21, and the temperature is regulated so that the inside of the control valve 2 is maintained at a predetermined temperature. For example, the temperature of the control valve 2 is set to a temperature higher than that of the liquid material in the tank TN and lower than that of the vaporizer 3 where the liquid material is vaporized. In other words, the liquid material flowing into the vaporizer 3 is preheated by the control valve 2 so that it is easily vaporized, and the temperature regulated by the valve heater 26 is set so that the liquid material does not vaporize inside the control valve 2.

[0038] The vaporizer 3 is configured to heat and reduce the pressure of the gas-liquid mixture to vaporize it and generate a material gas. Specifically, the vaporizer 3 includes a nozzle 31 whose flow path diameter expands downstream, and a vaporization heater 32 that heats the gas-liquid mixture flowing inside the nozzle 31.

[0039] Here, particularly when control valve 2 is opened from a fully closed state and liquid material suddenly flows into vaporizer VP, the temperature of control valve 2 will temporarily drop due to heat absorption by the liquid material itself or vaporization of the liquid material in vaporization section 3, even if it is heated by valve heater 26. More specifically, when the flow rate of liquid material is changed in a stepwise manner from a zero state, control valve 2 will gradually drop from its initial temperature in the fully closed state, and will be maintained at an equilibrium temperature where the heat absorption due to vaporization of the liquid material and the heating by valve heater 26 are balanced.

[0040] The control mechanism 4 realizes its functions through cooperation between a computer equipped with a CPU, memory, A / D converter, D / A converter, various input / output devices, etc., and various other devices. In the first embodiment, the control mechanism 4 controls the operation of the mass flow controller MFC and the vaporizer VP based on user settings. The control mechanism 4 inputs a target command, fixed at a certain set value, as the set flow rate of the carrier gas to the mass flow controller MFC, so that the carrier gas continues to be supplied at a fixed flow rate. The control mechanism 4 also controls the aperture of the control valve 2 of the vaporizer VP using PID control based on the set value indicating the set flow rate of the liquid material set by the user for the control valve 2 of the vaporizer VP and the measurement value measured by the liquid flow sensor 1. The control mechanism 4 is also characterized by being able to switch the integral gain during control of the control valve 2, particularly during control in response to a step command. More specifically, the vaporizer 100 executes a program stored in memory, and various devices cooperate to perform the functions of at least the valve controller 41, integral gain switching unit 42, and control parameter storage unit 43 shown in FIG. 3 . Each unit is described in detail below.

[0041] The valve controller 41 controls the aperture of the control valve 2 by PID control based on a set value indicating the set flow rate of the liquid material set by the user and the measured flow rate measured by the liquid flow sensor 1. This valve controller 41 includes a PID control unit 411 that performs PID calculations based on the deviation between the set value and the measured flow rate of the liquid material and a set PID gain, and calculates a target value for the applied voltage, which is a manipulated variable, and a voltage application unit 412 that outputs a voltage to the control valve 2 so that the applied voltage output from the PID control unit 411 becomes the target value. Here, the PID gains set in the PID control unit 411 include a proportional gain, an integral gain, and a differential gain, and in the first embodiment, the integral gain is switched from one value to another during control. On the other hand, the proportional gain and the differential gain are always fixed.

[0042] The integral gain switching unit 42 switches the integral gain set in the valve controller 41 from a reference integral gain to a correction integral gain during a transient response period of the flow rate measured by the liquid flow sensor 1. For example, when a step function is input as the set flow rate, as shown in the image diagram of FIG. 4, the integral gain switching unit 42 sets the reference integral gain until the flow rate measured by the liquid flow sensor 1 reaches a peak value, and sets the correction integral gain thereafter. Here, in the case where a step function with an initial value of zero is input as the set flow rate, the "transient response period of the flow rate" refers to a period beginning when the measured flow rate reaches a value other than the initial value (zero) and ending a predetermined time after the peak point at which the measured flow rate reaches its peak value. Note that if a temperature rise occurs in the valve seat 23 or valve element 24 of the control valve 2 and the measured flow rate at which the opening is increased is maintained at a value greater than the set value, the measured flow rate measured a predetermined time after the peak point may be greater than the set value, for example. Furthermore, if a temperature drop occurs at the valve seat 23 or valve element 24 due to a combination of the characteristics of the material of the control valve 2, the characteristics of the liquid material, the amount of heat, etc., causing a decrease in the opening, resulting in an overshoot followed by an undershoot, and the measured flow rate being lower than the set value, the measured flow rate measured a predetermined time after the peak point may be lower than the set value, for example. In other words, the transient response period can be defined as the period from when the flow rate rises from a state in which the flow rate is maintained at the initial value, reaches its peak value, and converges to the set value indicated by the set flow rate. Additionally, the transient response period may be more strictly defined as the rise period, which is the period from the start of the rise to the peak point, with the end point being the peak point.

[0043] The values ​​of the reference integral gain and the correction integral gain, and the determination conditions for using these integral gains are stored in the control parameter storage unit 43 in association with each other.

[0044] The reference integral gain is an integral gain set in accordance with the characteristics of the control valve 2, which is maintained at a normal operating temperature by the valve heater 26, for example. More specifically, the reference integral gain is set to the step response characteristic of a flow control system that does not include the vaporizing unit 3 and is composed only of the control valve 2 and the liquid flow sensor 1. Settling time is a value set so that the reference integral gain is within a predetermined allowable time. Here, the allowable time is a value determined, for example, based on constraints imposed on the flow rate of the material gas introduced into the chamber. The reference integral gain may be a value determined by computer simulation or may be a value determined experimentally.

[0045] On the other hand, the correction integral gain is set in accordance with the dynamic characteristics of the flow control system, which includes not only the control valve 2 and the liquid flow sensor 1 but also the vaporizer 3. Specifically, the step response when switching from the reference integral gain to the correction integral gain during the transient response period of the flow rate is Settling time The corrected integral gain is set so that the above-mentioned allowable time is within the above-mentioned range. For example, assuming the reference integral gain determined by the above-mentioned method, if the reference integral gain is changed to another integral gain during the transient response period by computer simulation or experiment, Settling time A value is searched for that satisfies the above-mentioned allowable time. As a result of the search, an integral gain that satisfies the conditions is used as the corrective integral gain. In the first embodiment, the corrective integral gain is set to a value greater than the reference integral gain. For example, the corrective integral gain is set to a value α×Ki obtained by multiplying the reference integral gain Ki by a correction coefficient α that is greater than 1.

[0046] Furthermore, in the first embodiment, the timing at which the integral gain switching unit 42 switches from the reference integral gain to the corrected integral gain is triggered by the start of the rise of the set flow rate. Specifically, the integral gain switching unit 42 switches the integral gain set in the valve controller 41 from the reference integral gain to the corrected integral gain after a predetermined time has elapsed, based on the start of the rise of the set value at the set flow rate, when the set value changes from zero to a predetermined flow rate value. In the first embodiment, the integral gain switching unit 42 switches from the reference integral gain to the corrected integral gain during a transient response period in the flow rate of the liquid material measured by the liquid flow sensor 1. As an example, the switching from the reference integral gain to the corrected integral gain occurs after the start of the rise of the flow rate of the liquid material, but before the reference peak point when the integral gain is controlled by fixing it to the reference integral gain. In other words, the integral gain is switched during the rise period of the flow rate of the measured liquid material. Note that, as will be described later, not only can the offset be eliminated, but the amount of overshoot can be reduced, Settling time In order to further reduce the time, it is preferable to switch from the reference integral gain to the correction integral gain after the flow rate of the liquid material starts to rise and before it reaches the step value at the set flow rate.

[0047] The step response of the vaporizer 100 of the first embodiment configured as above with respect to the flow rate control of the liquid material will be described below in comparison with the step response of a conventional example in which the reference integral gain is fixed.

[0048] As shown in Figure 5, when a step function with zero as the initial value is input as the set flow rate, the valve temperature drops with a first-order lag from the initial temperature to the terminal temperature near the point where the set flow rate starts to rise. If PID control is performed with a fixed reference integral gain as in the past due to this drop in temperature, the offset (steady-state deviation) between the set value and the measured value of the flow rate will be maintained for a long time after an overshoot occurs. In other words, in the conventional example, the temperature drop causes Settling time cannot be completed within the allowed time.

[0049] In contrast, in the vaporization device 100 of the first embodiment, when the reference integral gain is switched to the corrected integral gain at the reference peak point when the flow rate measured in the conventional example reaches its peak, as shown in Figure 6, the amount of overshoot remains almost the same, but the offset is quickly eliminated after the corrected integral gain is switched. Furthermore, no particular hunting or the like occurs after switching to the corrected integral gain.

[0050] Next, a case where the timing of switching the integral gain is made earlier in the vaporizer 100 of the first embodiment will be described with reference to Figures 7 and 8. Specifically, as shown in Figure 8, the timing is earlier than the reference peak point described above, and the timing is when the measured flow rate of the liquid material is smaller than the set value, and the reference integral gain is switched to the correction integral gain.

[0051] When the integral gain is switched at such timing, the vaporization device 100 of the first embodiment can reduce the amount of overshoot compared to the conventional example, as shown in FIGS. 7 and 8. Settling time It can be seen that the time can be further reduced. Furthermore, even if the corrective integral gain is switched at such a timing, no particular hunting or the like occurs.

[0052] In this way, with the vaporization device 100 of the first embodiment, the integral gain switching unit 42 can switch from the reference integral gain to a larger corrective integral gain during the transient response period of the flow rate of the liquid material. As a result, even if the temperature of the control valve 2 drops significantly when the liquid material starts to vaporize and thermal contraction occurs in the metals that make up the control valve 2, the opening required to eliminate the offset can be achieved. In addition, because the offset is eliminated, Settling time can be shortened to within the allowable time.

[0053] Furthermore, because control is performed using the reference integral gain for a predetermined period of time from the start of the rise of the liquid material, an excessive manipulated variable is not input to the control valve 2 during the transient response period, and large overshooting or hunting does not occur. In other words, if control is always performed using a corrected integral gain higher than the reference integral gain, there is a risk of unstable flow rate control. However, in the vaporizer 100 of the first embodiment, PID control is initially performed using a low reference integral gain, making such problems less likely to occur. Therefore, it is possible to improve the responsiveness of the vaporizer 100 while also achieving stable control.

[0054] Next, a modification of the vaporizer 100 of the first embodiment will be described.

[0055] The integral gain switching unit 42 may be configured to maintain the measured value of the flow rate of the liquid material at a set value after switching from the reference integral gain to the corrected integral gain, and then return to the reference integral gain after a predetermined time has elapsed. In this way, even if a disturbance is input while the flow rate is being maintained, the gain is less susceptible to the influence of the disturbance, thereby improving robustness.

[0056] The timing at which the integral gain switching unit 42 switches from the reference integral gain to the correction integral gain is not limited to the rise period during the transient response period as described in the first embodiment. That is, the integral gain may be switched during a period other than the rise period during the transient response period. In the first embodiment, the integral gain was switched during the rise period, but the integral gain may also be switched after the peak point and before the flow rate of the liquid material decreases and reaches the set flow rate. Furthermore, the integral gain may also be switched during the rise period, from the point at which the set flow rate step value is reached until the peak point.

[0057] The integral gain switching unit 42 may also be configured to set the timing for switching from the reference integral gain to the corrected integral gain in accordance with the magnitude of the set value indicated by the set flow rate. For example, the greater the difference between the set value indicated by the set flow rate and the initial value, the more delayed the switching timing based on the start point of the rise in the flow rate of the liquid material. The integral gain switching unit 42 may also be configured to set the timing for switching from the reference integral gain to the corrected integral gain in accordance with the type of liquid material. For example, the switching timing may be set in accordance with the physical properties of the liquid material, such as the specific heat and viscosity.

[0058] In the vaporization device 100 of the first embodiment, the valve controller 41 controls the control valve 2 by PID control, but it may also control by, for example, PI control. Even if PI control is used, by switching from the reference integral gain to the correction integral gain, it is possible to maintain the stability of the control while improving the control characteristics, as in the vaporization device 100 of the first embodiment.

[0059] Furthermore, although the first embodiment is configured to switch only the integral gain, the proportional gain and the differential gain may also be switched. That is, the vaporization device 100 is required to switch at least the integral gain. Furthermore, when switching multiple gains, the gains may be switched simultaneously, or the timing of switching each gain may be staggered. In addition, the integral gain may be switched discontinuously, or may be changed continuously from the reference integral gain to the correction integral gain within a predetermined time. That is, the "integral gain switching" is not limited to being defined by a discontinuous function, but may also be defined by a continuous function.

[0060] In the first embodiment, the set flow rate is a step function with an initial value of zero, but the application and subject of the present invention is not limited to this. For example, even if the initial value is maintained at a small flow rate and a step function that becomes a large flow rate halfway through is input as the set flow rate, it is thought that the temperature of the control valve 2 will drop significantly due to a large change in the amount of vaporization. Settling time It is believed that the problem regarding this can be solved by switching the integral gain in the same way as in the first embodiment. Furthermore, the function input as the set flow rate is not limited to a step function, and may be one in which the initial value and the final set value are connected by, for example, a ramp function. Furthermore, the initial value and the final set value may be connected by various methods such as S-shaped interpolation. In addition, in the first embodiment, the timing to switch from the reference integral gain to the corrected integral gain is determined by, for example, the step response Settling time was set as the allowable time, but this was also determined based on the various flow rate responses. Settling time For example, the ramp response Settling time The timing of switching the integral gain may be set so that the time is within the allowable time, or the flow rate response when the set flow rate is input by S-shaped interpolation between the initial value and the final set value as described above. Settling time In addition, when a set flow rate is input that is interpolated between the initial value and the final target value using various other methods or functions, the flow rate response may be calculated. Settling time The timing of switching the integral gain may be determined based on the above.

[0061] The vaporizing section 3 may be one that vaporizes the liquid material only by reducing the pressure, or one that vaporizes the liquid material only by heating.

[0062] As shown in FIG. 9 , the vaporizer VP may be one in which the control valve 2 and the vaporizing unit 3 are integrated. That is, the vaporizing unit 3 may be configured by forming a nozzle 31 that reduces the flow path area in the flow path connecting the valve seat 23 and the liquid outlet port P3 in the body 21 of the control valve 2. In such a case, the control valve 2 is configured by the flow path from the liquid inlet port P1 and the gas inlet port P2 on the upstream side of the body 21 to the valve seat 23, as well as an actuator such as the diaphragm structure 22 and the piezoelectric actuator 25, and the nozzle 31 formed in the body 21 downstream of the valve seat 23 is configured as the vaporizing unit. Alternatively, the control point of the liquid material in the control valve 2 may be aligned with the vaporizing point in the vaporizing unit 3. That is, instead of providing the nozzle 31, the gap between the valve seat 23 and the valve element 24 of the control valve 2 itself may be used as the vaporizing unit 3, thereby simultaneously performing flow rate control and vaporization in a single configuration. In other words, the valve seat 23 and valve element 24 of the control valve 2 may themselves be configured as the vaporizing unit 3. The positional relationship between the control valve 2 and the vaporizing unit 3 may be such that they are at the same point in terms of flow rate, or that the vaporizing unit 3 is located downstream of the control valve 2.

[0063] In the vaporization device 100 of the first embodiment, the problem of flow rate control caused by a temperature drop in the control valve 2 and an increase in the opening degree was solved by switching the integral gain during the transient response period, but this configuration and method can also solve the problem of flow rate control caused by a temperature rise in the control valve 2 and a decrease in the opening degree.

[0064] The control mechanism 4 may further include a correction integral gain change unit 44 that changes the correction integral gain. Here, the correction integral gain change unit 44 may change the correction integral gain itself, or may change a value constituting the correction integral gain. For example, the manner in which the value constituting the correction integral gain is changed includes at least one of changing the reference integral gain Ki or changing the correction coefficient α of the correction integral gain, which is a value α×Ki obtained by multiplying the reference integral gain Ki by the correction coefficient α. The correction integral gain change unit 44 of this embodiment changes the correction coefficient α and outputs the changed correction coefficient α to the control parameter storage unit 43.

[0065] Here, the correction coefficient α is changed using temperature-related parameters related to the temperature drop of the control valve 2. Examples of the temperature-related parameters include the type of liquid material, the set flow rate of the liquid material, the set pressure of the liquid material, the set flow rate of the carrier gas, the measured flow rate of the liquid material, the measured pressure upstream of the control valve 2, the measured pressure downstream of the control valve 2, the set temperature of the control valve 2, the set temperature of the vaporizing unit 3, and the ambient temperature.

[0066] Regarding temperature-related parameters, the type of liquid material is data indicating physical properties such as viscosity or specific heat, the concentration of the liquid material, and the name of the liquid material. The set flow rate of the liquid material, the set pressure of the liquid material, the set flow rate of the carrier gas, and the set temperature of the control valve 2 are set values ​​input to the valve controller 41 and may be signals accompanying the input of the set values ​​to the valve controller 41 or values ​​calculated by converting the set values. The measured flow rate of the liquid material may be a measurement value of the liquid flow sensor 1, a signal indicating the measurement value of the liquid flow sensor 1, or a value calculated by converting the measurement value. The measured pressures upstream of the control valve 2 and downstream of the control valve 2 may be measurements of a pressure sensor (not shown), a signal indicating the measurement value of the pressure sensor (not shown), or values ​​calculated by converting the measurement value. The ambient temperature is the temperature around the vaporizer VP or the liquid flow sensor 1 in the vaporization device 100, and the measured ambient temperature may be a signal indicating the measurement value of a temperature sensor (not shown) or a value calculated by converting the measurement value.

[0067] The correction integral gain change unit 44 changes the correction coefficient α to one obtained using relational data indicating the relationship between the temperature-related parameters and the correction coefficient α. The relational data may be in the form of an equation that expresses the relationship between at least one of the temperature-related parameters (e.g., the type of liquid material, the set temperature, and the set flow rate) and the correction coefficient α, or in the form of a table that expresses the relationship between at least one of the temperature-related parameters and the correction coefficient α, or in the form of a graph that expresses the relationship between at least one of the temperature-related parameters and the correction coefficient α.

[0068] Here, if the temperature-related parameter used in the relationship data consists of only a constant set value (e.g., set pressure or set temperature) regardless of changes in the set flow rate of the liquid material, the correction coefficient α can be calculated using the relationship data by inputting that set value regardless of whether the set flow rate of the liquid material is changed or not. Note that the difference between before and after a change in the set flow rate of the liquid material may also be used as a parameter of the relationship data. In this case, it is desirable to create relationship data for each difference.

[0069] On the other hand, if the temperature-related parameters used in the relationship data include measured values ​​(e.g., measured flow rate, measured pressure, or measured temperature, hereinafter referred to as measured values ​​for creating relationship data) that change with a change in the set flow rate of the liquid material, the correction coefficient α can be obtained using the relationship data by inputting the measured values ​​at the time when the measured values ​​for creating the relationship data were measured (e.g., before a change in the set flow rate of the liquid material, during the transient response period after a change in the liquid material, etc.).

[0070] The relational data may be stored in a relational data storage unit (not shown) provided in the control mechanism 4, or may be stored in a computing device provided separately from the vaporization device 100.

[0071] When the relational data is stored in the relational data storage unit of the control mechanism 4, the corrected integral gain change unit 44 calculates the correction coefficient α using the relational data and changes the corrected integral gain by outputting the correction coefficient α to the control parameter storage unit 43. Note that Fig. 10 shows an example in which the correction coefficient α is calculated using the set flow rate of the liquid material or the set pressure of the liquid material.

[0072] On the other hand, if the relationship data is stored in a calculation device provided separately from the vaporization device 100, the correction coefficient α can be calculated using the relationship data by inputting parameters into the calculation device. By inputting this correction coefficient α to the control mechanism 4, the correction integral gain change unit 44 receives the correction coefficient α and outputs it to the control parameter storage unit 43 to change the correction integral gain. Here, the parameters can be input to the calculation device by a user inputting temperature-related parameters, by the control mechanism 4 inputting temperature-related parameters, or by a host control device of the control mechanism 4 inputting temperature-related parameters, etc. Furthermore, the correction coefficient α obtained by the calculation device can be input to the control mechanism 4 by a user inputting it to the control mechanism 4, by the calculation device inputting it to the control mechanism 4, or by the calculation device transmitting it to the host control device, which then inputs it to the control mechanism 4, etc.

[0073] Next, a fluid control device 101 according to a second embodiment of the present invention will be described with reference to FIGS.

[0074] The fluid control device 101 of the second embodiment is installed in an operating environment in which the control valve 2 experiences a temperature drop of a predetermined value or more after the rise of the measured value of the flow rate or pressure measured by the fluid sensor during control by the valve controller 41. That is, although the fluid control device 101 is not the vaporizer 100, the temperature of the control valve 2 drops with the start of the inflow of the fluid, similarly to the first embodiment, and similarly, in PID control using a fixed integral gain, the offset is not eliminated or the desired temperature is not obtained. Settling time However, this may not be possible.

[0075] Specifically, the fluid control device 101 of the second embodiment is a mass flow controller, and is provided together with a plurality of other mass flow controllers in a gas box, as shown in Fig. 9. Each mass flow controller individually controls the flow rate of a different fluid. The temperature inside such a gas box is higher than the ambient temperature, such as room temperature, due to heat generated by the mass flow controller itself. If the temperature of the inflowing fluid is lower than that of the mass flow controller, a control problem may arise due to the temperature drop, as in the first embodiment.

[0076] As shown in FIG. 11, the fluid control device 101 of the second embodiment has a control valve 2, a pressure or a flow rate measurement The second embodiment is equipped with a fluid sensor 11 that detects a flow rate of a fluid flow and a control mechanism 4 that controls the opening of a control valve 2 based on the deviation between the measurement value of the fluid sensor 11 and a set value. The configuration of the control mechanism 4 is substantially the same as that of the first embodiment, except for the control input and the controlled object. That is, when a step target command is input to the mass flow controller MFC of the second embodiment that is provided in the gas box, an integral gain switching unit 42 is configured to switch the integral gain set in the valve controller 41 from the reference integral gain to the correction integral gain during the transient response period of the measurement value of the fluid sensor.

[0077] In the fluid control device 101 of the second embodiment, the offset is not eliminated in an application where a temperature drop of the control valve 2 may occur, similar to the vaporizer VP of the first embodiment, or Settling time This solves the problem of being unable to shorten the time while also achieving control stability.

[0078] Next, a modification of the second embodiment will be described.

[0079] The fluid control device 101 of the second embodiment is not limited to one that controls flow rate, but may also be one that controls pressure. Furthermore, the fluid may be any of liquid, gas, and gas-liquid mixture. Furthermore, the control method of the fluid control device 101 of the second embodiment is applicable as long as the control valve 2 is at a high temperature and the temperature decreases due to the inflow of fluid. In other words, it is not limited to the one housed in the gas box as described above, and is applicable to various fluid control devices. Furthermore, even when the temperature of the control valve 2 increases due to the inflow of fluid, for example, an offset that reduces the flow rate relative to the set value can be eliminated, Settling time In other words, the present invention is applicable as long as the control valve is installed in an operating environment where a temperature change of a predetermined value or more occurs after the rise of the measurement value measured by the fluid sensor during control by the valve controller.

[0080] As in the first embodiment, in the second embodiment, the control mechanism 4 may further include a correction integral gain change unit 44 that changes the correction integral gain.

[0081] In addition, various combinations and modifications of the embodiments may be made as long as they do not go against the spirit of the present invention. [Explanation of symbols]

[0082] 100 Vaporizer 1. Liquid flow sensor 2. Control valve 3 Vaporization section 4. Control mechanism 41 Valve controller 42 Integral gain switching section 101 Fluid control device 11 Fluid Sensor GB Gas Box

Claims

1. a control valve provided in a flow path through which the liquid material flows; a vaporization section in which the liquid material is vaporized by decompression or heating; a liquid flow sensor for measuring the flow rate of the liquid material flowing through the flow path; a valve controller that controls the control valve by PI control or PID control based on a set value indicated by a set flow rate and a flow rate measured by the liquid flow rate sensor, an integral gain switching unit that switches an integral gain set in the valve controller from a reference integral gain to a correction integral gain different from the reference integral gain during a transient response period of a flow rate measured by the liquid flow sensor; A vaporization device, characterized in that the correction integral gain is set to a value higher than the reference integral gain.

2. 2. The vaporizer according to claim 1, wherein the reference integral gain is a value set so that the settling time of the flow rate response in the absence of the vaporizer falls within a predetermined allowable time.

3. 3. The vaporization device according to claim 2, wherein the correction integral gain is a value determined so that the settling time of the flow rate response when the vaporization section is present and when switching from the reference integral gain to the correction integral gain during the transient response period is within the allowable time.

4. 4. The vaporization device according to claim 1, wherein an integral gain switching unit changes the integral gain set in the valve controller from the correction integral gain to the reference integral gain after the measurement value has converged to the set value.

5. 4. The vaporization device according to claim 1, wherein the integral gain switching unit switches the integral gain set in the valve controller from the reference integral gain to the correction integral gain after a predetermined time has elapsed based on the start point of the rise of the set flow rate.

6. 4. A vaporization device as described in any one of claims 1 to 3, wherein the timing for switching from the reference integral gain to the corrected integral gain is set within the period from the start of the rise of the flow response to the peak when the control valve is continued to be controlled with the reference integral gain fixed.

7. The vaporization device of any one of claims 1 to 3, wherein the integral gain switching unit is configured to set the switching timing for switching from the reference integral gain to the corrected integral gain according to the magnitude of the set value indicated by the set flow rate or the type of the liquid material.

8. The vaporization device according to claim 1 , further comprising a correction integral gain change unit that changes the correction integral gain.

9. 9. The vaporization device of claim 8, wherein the correction integral gain change unit changes the correction integral gain based on at least one of the type of liquid material, the set flow rate of the liquid material, the set pressure of the liquid material, the set flow rate of the carrier gas, the pressure upstream of the control valve, the pressure downstream of the control valve, the set temperature of the control valve, the set temperature of the vaporization unit, or the ambient temperature.

10. The control valve a liquid introduction port into which the liquid material is introduced; a gas inlet port into which a carrier gas is introduced; The vaporization device according to claim 1 , further comprising: an outlet port through which a gas-liquid mixture obtained by mixing the liquid material and the carrier gas is discharged to the outside.

11. 4. The vaporizer according to claim 1, wherein the control valve and the vaporizer are provided adjacent to each other.

12. A control method for a vaporization device including a control valve provided in a flow path through which a liquid material flows, a vaporization unit in which the liquid material is vaporized by reducing pressure or heating, and a liquid flow rate sensor that measures the flow rate of the liquid material flowing through the flow path, comprising: Controlling the control valve by PI control or PID control based on a set value indicated by a set flow rate and a flow rate measured by the liquid flow rate sensor; during a transient response period of the flow rate measured by the liquid flow sensor, switching an integral gain set in a valve controller from a reference integral gain to a correction integral gain different from the reference integral gain; A vaporizer control method, wherein the correction integral gain is set to a value higher than the reference integral gain.

13. A control program used in a vaporization device including a control valve provided in a flow path through which a liquid material flows, a vaporization unit in which the liquid material is vaporized by reducing pressure or heating, and a liquid flow rate sensor that measures the flow rate of the liquid material flowing through the flow path, a valve controller that controls the control valve by PI control or PID control based on a set value indicated by a set flow rate and a flow rate measured by the liquid flow rate sensor; causing a computer to function as an integral gain switching unit that switches an integral gain set in the valve controller from a reference integral gain to a correction integral gain different from the reference integral gain during a transient response period of a flow rate measured by the liquid flow sensor; The vaporizer program according to claim 1, wherein the correction integral gain is set to a value higher than the reference integral gain.

14. a control valve provided in a flow path through which the fluid flows; a valve controller that controls the control valve by PI control or PID control using a set value of a flow rate or pressure indicated by a target command and a measurement value measured by a fluid sensor, the control valve is installed in an operating environment in which a temperature change of a predetermined value or more occurs after a rise in a measurement value measured by the fluid sensor during control by the valve controller, an integral gain switching unit that switches an integral gain set in the valve controller from a reference integral gain to a correction integral gain different from the reference integral gain during a transient response period of a measurement value measured by the fluid sensor; A fluid control device, characterized in that the correction integral gain is set to a value higher than the reference integral gain.

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