Liquid material vaporizing device, method for controlling liquid material vaporizing device, and program for controlling liquid material vaporizing device

Abstract

This liquid material vaporizing device comprises: a tank 1 that stores a liquid material and in which the liquid material is vaporized; a supply path R1 that supplies the liquid material to the tank 1; a liquid level detection unit 2 that detects at least a first liquid level that is one of the liquid levels in the tank 1; a valve V1 that is provided in the supply path R1 and opens and closes the supply path R1; and a valve control unit 41 that opens the valve V1 to supply the liquid material to the tank 1 when the liquid level in the tank 1 is less than the first liquid level. The valve control unit 41 provides a closing duration at least once in which the closed state of the valve V1 continues until the liquid level in the tank 1 reaches the first liquid level from a level less than the first liquid level.

Description

Liquid material vaporizer, liquid material vaporizer control method, and liquid material vaporizer control program

[0001] The present invention relates to a liquid material vaporizer that heats and vaporizes a liquid material, a control method for a liquid material vaporizer, and a control program for a liquid material vaporizer.

[0002] Conventionally, liquid material vaporizers have been developed that generate gases used in semiconductor manufacturing processes by vaporizing liquid materials. Therefore, miniaturization of vaporizers is required so that multiple vaporizers can be installed in semiconductor manufacturing equipment. For example, as shown in Patent Document 1, this type of liquid material vaporizer includes a small vaporization tank that vaporizes the liquid material by, for example, a baking method, an electromagnetic on-off valve that controls the amount of liquid material supplied to the vaporization tank, a preheater that preheats the liquid material supplied to the vaporization tank to a predetermined temperature, and a liquid level sensor that detects the amount of liquid material stored in the vaporization tank.

[0003] Since the amount of liquid material stored in a small vaporization tank is small, a liquid level sensor constantly detects the amount of liquid material stored in the vaporization tank and controls the liquid level in the vaporization tank by controlling the opening and closing of the electromagnetic valve according to the amount of liquid material stored.

[0004] Japanese Patent Application Laid-Open No. 2019-85611

[0005] Here, in the above-mentioned liquid material vaporization device, when the amount of liquid material stored in the vaporization tank falls below a predetermined level, the electromagnetic valve is kept open at all times to supply the liquid material to the vaporization tank until the predetermined level is reached.

[0006] However, if the electromagnetic valve is always open when supplying the liquid material to the vaporization tank, the liquid material will be supplied to the vaporization tank all at once, causing a drop in temperature and pressure fluctuations in the vaporization tank. For example, if the temperature of the liquid material is sufficiently lower than the temperature in the vaporizer, the temperature in the vaporization tank will drop and the pressure in the vaporization tank will temporarily drop. Furthermore, if a large amount of liquid material is supplied to the vaporization tank all at once, the internal pressure in the vaporization tank will temporarily rise, which will also cause pressure fluctuations in the vaporization tank.

[0007] In addition, in order to use a float sensor or the like, which has high operational reliability, to detect the amount of liquid material stored in the vaporization tank, it has been considered to omit the preheater in order to increase the capacity of the vaporization tank. In this case, the temperature of the liquid material supplied to the vaporization tank will be even lower, making it more likely that temperature drops and pressure fluctuations will occur inside the vaporization tank.

[0008] The present invention has been made in view of the above problems, and its main object is to suppress a temperature drop and pressure fluctuation inside a tank when a liquid material is supplied to the tank.

[0009] That is, the liquid material vaporization device of the present invention comprises a tank for storing liquid material and vaporizing the liquid material inside, a supply path for supplying the liquid material to the tank, a liquid level detection unit for detecting at least a first liquid level which is one of the liquid levels in the tank, a valve provided in the supply path for opening and closing the supply path, and a valve control unit for opening the valve to supply the liquid material to the tank when the liquid level in the tank is below the first liquid level, and is characterized in that the valve control unit provides a closed duration period in which the valve remains closed at least once during the time period from when the liquid level in the tank rises from below the first liquid level to the first liquid level.

[0010] With this configuration, there is at least one closed duration while the liquid level in the tank rises from below the first liquid level to the first liquid level, so the valve is not always open, and the amount of liquid material supplied to the tank per open duration while the valve is continuously open can be reduced. As a result, the temperature drop and pressure fluctuation in the tank can be suppressed more than before while the liquid level in the tank rises from below the first liquid level to the first liquid level.

[0011] In particular, in a liquid material vaporization device that does not have a preheater, the temperature of the liquid supplied to the tank is lower than in a liquid material vaporization device that has a preheater, making it more likely that temperature drops and pressure fluctuations will occur inside the tank.However, with the above configuration, even in a liquid material vaporization device that does not have a preheater, temperature drops and pressure fluctuations inside the tank can be suppressed.

[0012] Specifically, the valve control unit is characterized by repeating the open duration during which the valve remains open and the closed duration at least once during the time period from when the liquid level in the tank changes from below the first liquid level to when it reaches the first liquid level.

[0013] With this configuration, the valve is opened and closed at least once each during the time it takes for the liquid level in the tank to rise from below the first level to the first level, thereby ensuring that the amount of liquid material supplied during each open period is reduced.

[0014] It is preferable that the valve control unit closes the valve when the liquid level in the tank reaches the first liquid level before an open duration during which the valve remains open has elapsed.

[0015] With this configuration, the valve closes when the liquid level in the tank reaches the first liquid level even if the open duration has not elapsed, so that the required amount of liquid material can be reliably supplied to the tank and more liquid material than necessary can be prevented from being supplied to the tank.

[0016] When a flow control device such as a mass flow controller (hereinafter also referred to as MFC) is provided downstream of a tank, if the valve is kept open all the time as in the past while the liquid level in the tank rises from below the first liquid level to the first liquid level, the flow rate output from the MFC will fluctuate. This hunting is thought to occur when the temperature inside the tank drops when the liquid material is supplied, causing a drop in the pressure inside the tank, or when a large amount of liquid material is supplied, causing a temporary rise in the internal pressure of the tank.

[0017] Therefore, it is preferable that the liquid material vaporization device further includes a gas outlet path that discharges the vaporized gas generated by vaporizing the liquid material from the tank, and a flow rate controller that controls the flow rate of the vaporized gas flowing through the gas outlet path.

[0018] With this configuration, pressure fluctuations within the tank when the liquid material is supplied to the tank are suppressed, and therefore hunting of the flow rate output from the flow rate controller can be prevented.

[0019] It is desirable that the valve control unit changes the length of the open duration during which the valve remains open and / or the length of the closed duration depending on the set flow rate of the vaporized gas set in the flow rate controller.

[0020] With this configuration, the length of the open duration and the closed duration are changed depending on the set flow rate of the vaporized gas, thereby reducing hunting of the flow rate output by the flow rate controller at each set flow rate.

[0021] Specifically, it is preferable that the valve control section shortens the length of the open duration as the set flow rate increases.

[0022] With this configuration, although the greater the set flow rate, the greater the fluctuation in the flow rate output by the flow rate controller while the liquid material is being supplied to the tank, it is possible to suppress the fluctuation in the flow rate output by the flow rate controller while the liquid material is being supplied to the tank even when the set flow rate is large. It is desirable that the valve control unit set the length of the open duration to 0 when the set flow rate is equal to or less than a predetermined value.

[0023] With this configuration, the open duration is set to 0 when the set flow rate is equal to or lower than a predetermined value, so that hunting of the flow rate output by the flow rate controller can be completely suppressed.

[0024] The valve control unit preferably sets the length of the closed duration to be longer than the length of the open duration.

[0025] With this configuration, the length of the closed duration is longer than the length of the open duration, so by keeping the valve closed until the temperature drop and pressure fluctuations inside the tank that occur with one open duration have subsided, it is possible to prevent the temperature drop and pressure fluctuations inside the tank from expanding when the next open duration begins.

[0026] Furthermore, a control method for a liquid material vaporization device comprising a tank for storing liquid material and vaporizing the liquid material inside, a supply path for supplying the liquid material to the tank, a liquid level detection unit for detecting at least a first liquid level which is one of the liquid levels in the tank, and a valve provided in the supply path for opening and closing the supply path is characterized in that a closed duration period in which the valve remains closed is provided at least once during the time period from when the liquid level in the tank rises from below the first liquid level to the first liquid level.

[0027] Furthermore, a control program for a liquid material vaporization device comprising a tank for storing liquid material and vaporizing the liquid material inside, a supply path for supplying the liquid material to the tank, a liquid level detection unit for detecting at least a first liquid level which is one of the liquid levels in the tank, and a valve provided in the supply path for opening and closing the supply path is characterized in that it causes a computer to perform the function of a valve control unit for providing a closed duration period in which the valve remains closed at least once during the time period from when the liquid level in the tank rises from below the first liquid level to when it reaches the first liquid level.

[0028] With this configuration, it is possible to obtain the same effects as those of the liquid material vaporizing device described above.

[0029] Here, when the flow rate controller controls the flow rate of vaporized gas, supplying a liquid material to the tank causes pressure fluctuations in the tank, which may cause hunting in the flow rate output by the flow rate controller.

[0030] A liquid material vaporization apparatus equipped with a flow rate controller that controls the flow rate of vaporized gas generated by vaporizing a liquid material includes a tank that stores the liquid material and vaporizes the liquid material therein, a supply path that supplies the liquid material to the tank, a valve provided in the supply path that opens and closes the supply path, and a valve control unit that opens the valve to supply the liquid material to the tank, wherein the valve control unit adjusts the aperture of the valve in response to a set flow rate of the vaporized gas set in the flow rate controller, a flow rate sensor provided in the flow rate controller, or a drive signal for a flow rate control valve provided in the flow rate controller. Also, a control method for a liquid material vaporization apparatus equipped with a tank that stores the liquid material and vaporizes the liquid material therein, a supply path that supplies the liquid material to the tank, and a valve provided in the supply path that opens and closes the supply path is characterized by adjusting the aperture of the valve in response to a set flow rate of the vaporized gas set in the flow rate controller, a flow rate sensor provided in the flow rate controller, or a drive signal for a flow rate control valve provided in the flow rate controller. Furthermore, a control program for a liquid material vaporization device comprising a tank for storing the liquid material and vaporizing the liquid material inside, a supply line for supplying the liquid material to the tank, and a valve provided in the supply line for opening and closing the supply line is characterized in that it causes a computer to function as a valve control unit that adjusts the opening degree of the valve in accordance with the set flow rate of the vaporized gas set in the flow rate controller, a flow rate sensor provided in the flow rate controller, or a drive signal of a flow rate control valve provided in the flow rate controller.

[0031] With this configuration, the valve opening is adjusted according to the set flow rate of the vaporized gas, the flow rate sensor, or the drive signal of the flow rate control valve. Therefore, when the flow rate controller is controlling the flow rate of the vaporized gas, pressure fluctuations in the tank caused by supplying liquid material to the tank can be suppressed, and hunting of the flow rate output by the flow rate controller can be suppressed.

[0032] Specifically, when the vaporized gas is generated in the tank, it is preferable that the valve control unit closes the valve when the set flow rate is equal to or greater than a predetermined threshold, and opens the valve when the set flow rate is less than the threshold.

[0033] With this configuration, the valve is closed when the set flow rate is equal to or greater than the threshold, preventing tank pressure fluctuations caused by supplying liquid material to the tank. Therefore, hunting of the flow rate output by the flow rate controller can be further suppressed. Additionally, while the output of the flow rate sensor becomes inaccurate if, for example, a blockage occurs in the flow path through which the vaporized gas flows, the valve control unit controls the opening and closing of the valve based on the set flow rate of the vaporized gas, allowing for more accurate control of the vaporized gas flow rate compared to the output of the flow rate sensor or the drive signal of the flow rate control valve.

[0034] In order to ensure that pressure fluctuations in the tank due to supply of liquid material to the tank do not occur, it is desirable that the threshold value be 0.

[0035] According to the present invention, it is possible to suppress a temperature drop and pressure fluctuation inside the tank when supplying a liquid material to the tank.

[0036] 1 is a schematic diagram showing the configuration of a liquid material vaporization device according to a first embodiment of the present invention; 2 is a flowchart showing a control method for the liquid material vaporization device according to the same embodiment; 3 is a graph showing the relationship between the set flow rate of the vaporized gas, the open / close state of the valve, and the liquid level in the tank according to the same embodiment; and 4 is a flowchart showing a control method for the liquid material vaporization device according to a second embodiment.

[0037] First Embodiment of the Present Invention A liquid material vaporization device according to a first embodiment of the present invention will be described below with reference to the drawings. Note that in all of the drawings shown below, some parts may be omitted or exaggerated as appropriate for ease of understanding. Identical components will be assigned the same reference numerals and their description will be omitted as appropriate.

[0038] <Device Configuration> As shown in FIG. 1 , the liquid material vaporization device 100 of this embodiment includes a tank 1 that stores the liquid material and vaporizes it inside, a supply path R1 that supplies the liquid material to the tank 1, a heater (not shown as it is attached to the tank 1) that heats the liquid material in the tank 1, a liquid level detection unit 2 that detects the liquid level in the tank 1, a first on-off valve V1 that is provided in the supply path R1 and opens and closes the supply path R1, a gas outlet path R2 that outputs vaporized gas generated when the liquid material is heated in the tank 1, a flow rate controller 3 that performs feedback control to keep the flow rate of the vaporized gas flowing through the gas outlet path R2 at a predetermined value, a control device 4 that controls at least the first on-off valve V1, a purge gas introduction path R3 that introduces purge gas to the flow rate controller 3, and a housing 5 that accommodates and holds these components.

[0039] The tank 1 is a hollow rectangular parallelepiped tank made of stainless steel or the like.

[0040] The supply path R1 is formed by drilling holes in a tube or block, and one end of the supply path R1 is connected to the bottom surface of the tank 1, while the other end is connected to a first port P1 provided in the housing 5. This first port P1 is connected to a liquid material source (not shown) via a tube, a tube, or the like. Only a first on-off valve V1 is provided in the supply path R1 from the first port P1 to the tank 1, and no preheater, for example, is provided to preheat the liquid material to be supplied to the tank 1 to a predetermined temperature, although a preheater may be provided.

[0041] The liquid level detection unit 2 includes two float sensors 21 and 22. Each float sensor 21 and 22 has a float that is held movable up and down within a predetermined height range and detects whether the float is floating due to buoyancy from the liquid material in the tank 1. One float sensor 21 functions as a low-level sensor that detects whether the liquid level in the tank 1 is below a predetermined first liquid level, while the other float sensor 22, whose float is set at a higher position within the range of vertical movement, functions as a high-level sensor that detects whether the liquid level in the tank 1 is above a predetermined second liquid level. Here, the first liquid level is the lower limit of the liquid level in the tank 1, and the second liquid level is the upper limit of the liquid level in the tank 1. That is, these two float sensors 21 and 22 can detect three states: whether the liquid level in the tank 1 is below the lower limit, between the lower limit and the upper limit, or above the upper limit. In the following, when the liquid level in tank 1 is below the first liquid level, it will be referred to as a low liquid level, when the liquid level in tank 1 is above the first liquid level but below the second liquid level, it will be referred to as a medium liquid level, and when the liquid level in tank 1 is above the second liquid level, it will be referred to as a high liquid level.

[0042] The first on-off valve V1 is provided on the supply path R1 and is the only valve capable of controlling the flow of fluid through the supply path R1. The first on-off valve V1 is, for example, a pneumatic valve that can be remotely operated to open and close, but is not limited to this. The first on-off valve V1 in this embodiment can be switched between two states: an open state and a closed state. When the first on-off valve V1 is in the open state, the opening degree is 100% only, and when the first on-off valve V1 is in the closed state, the opening degree is 0%. A pressure pump (not shown) is provided downstream of the first on-off valve V1 to supply the liquid material to the tank 1 when the first on-off valve V1 is opened.

[0043] The gas outlet path R2 is formed by drilling a hole in a pipe or a block, and one end of the path is connected to the top surface of the tank, while the other end is connected to a second port P2 provided in the housing 5. This second port P2 is connected to a target device such as a semiconductor process chamber (not shown) via a tube, pipe, or the like.

[0044] A second on-off valve V2 is provided on the gas outlet path R2. Here, a pneumatic valve type that can be remotely operated to open and close is used as the second on-off valve V2, but the present invention is not limited to this.

[0045] The flow rate controller 3 is, for example, a mass flow controller (hereinafter also referred to as MFC) that is provided on the gas outlet path R2 between the second on-off valve V2 and the second port P2 and controls the mass flow rate of the fluid flowing through this gas outlet path R2. This flow rate controller 3 includes a flow rate control valve (not shown) and, for example, a thermal flow rate sensor, and performs feedback control of the opening of the flow rate control valve so that the measured flow rate measured by this flow rate sensor approaches a preset set flow rate.

[0046] The control device 4 constitutes a so-called computer equipped with a CPU, memory, A / D converter, D / A converter, and various input / output devices, and performs the functions of a valve control unit 41 that opens the first on-off valve V1 to supply the liquid material to the tank 1 when the liquid level in the tank 1 is below the first liquid level, and a flow rate control unit 42 that controls the flow rate controller 3. Specific aspects of the valve control unit 41 will be described later.

[0047] The purge gas inlet path R3 is formed by drilling holes in a tube or a block, and one end of the path R3 is connected to the gas outlet path R2, more specifically, between the second on-off valve V2 and the flow rate controller 3, and the other end of the path R3 is connected to a third port P3 provided in the housing 5. The third port P3 is connected to a purge gas source (not shown) via a tube, a tube, or the like.

[0048] A third on-off valve V3 is provided on the purge gas introduction passage R3. Here, a pneumatic valve type that can be remotely operated to open and close is used as the third on-off valve V3, but the present invention is not limited to this.

[0049] The purge gas introduction path R3 can be used when purging only the flow rate controller 3. At this time, the second on-off valve V2 is closed, the third on-off valve V3 is opened, and the purge gas introduced from the purge gas introduction path R3 passes through the flow rate controller 3 and is discharged from the second port P2.

[0050] In FIG. 1, reference numeral 6 denotes a pressure sensor that measures the pressure inside the tank 1 .

[0051] <Aspects of Valve Control Unit> Next, an aspect of the valve control unit 41 in the liquid material vaporizing apparatus 100 having the above-described configuration will be described.

[0052] The valve control unit 41 provides a closed duration during which the closed state of the first on-off valve V1 continues at least once during the time period from when the liquid level in the tank 1 rises from below the first liquid level to the first liquid level. In other words, the valve control unit 41 limits the open duration, which is the time during which the open state of the first on-off valve V1 continues, without constantly opening the first on-off valve V1. Specifically, the valve control unit 41 repeats the open duration and the closed duration, which is the time during which the closed state of the first on-off valve V1 continues, at least once during the time period from when the liquid level in the tank 1 rises from below the first liquid level to the first liquid level. In this embodiment, the closed duration is a time period greater than zero.

[0053] In the liquid material vaporizing apparatus 100 having the above configuration, the opening and closing control of the first opening and closing valve V1 by the valve control unit 41 will be described below with reference to the flowchart of FIG.

[0054] When the valve control unit 41 controls the opening and closing of the first opening and closing valve V1, the liquid material in the tank 1 is heated to generate vaporized gas, and the flow rate controller 4 controls the flow rate of the vaporized gas. In this state, the first opening and closing valve V1 is closed (S0). The valve control unit 41 also constantly acquires the liquid level in the tank 1 from the liquid level detection unit 2. The valve control unit 41 then determines whether the liquid level in the tank 1 is below the first liquid level (S1). If the liquid level in the tank 1 is equal to or higher than the first liquid level, the process returns to S1.

[0055] On the other hand, when the liquid level in the tank 1 is lower than the first liquid level, the valve control unit 41 opens the first opening / closing valve V1 to supply the liquid material to the tank 1 (S2).

[0056] Then, the valve control unit 41 determines whether the liquid level in the tank 1 reaches the first liquid level before the open duration time has elapsed (S3). If the liquid level in the tank 1 reaches the first liquid level, the valve control unit 41 closes the first opening / closing valve V1 (S4) and returns to S1.

[0057] On the other hand, if the liquid level in the tank 1 is below the first liquid level, the valve control unit 41 keeps the first on-off valve V1 open (S5). Then, the valve control unit 41 determines whether the open duration has elapsed (S6). Until the open duration has elapsed, the valve control unit 41 constantly determines whether the liquid level in the tank 1 has reached the first liquid level. On the other hand, if the open duration has elapsed, the valve control unit 41 closes the first on-off valve V1 (S7).

[0058] After the open duration has elapsed and the first on-off valve V1 is closed, the first on-off valve V1 remains closed until the closure duration has elapsed. When the closure duration has elapsed, the valve control unit 41 determines whether the liquid level in the tank 1 is at the first liquid level (S8).

[0059] When the liquid level in the tank 1 reaches the first liquid level, the valve control unit 41 keeps the first opening / closing valve V1 closed and returns to S1.

[0060] On the other hand, if the liquid level in the tank 1 is below the first liquid level, the valve control unit 41 opens the first opening / closing valve V1 again, and the opening / closing control of the first opening / closing valve V1 from S2 is continued.

[0061] Furthermore, in this embodiment, the valve control unit 41 changes the length of the open duration and / or the length of the closed duration in accordance with the set flow rate of the vaporized gas set in the flow rate controller 3. Specifically, the valve control unit 41 shortens the length of the open duration as the set flow rate increases.

[0062] More specifically, the valve control unit 41 stores a correspondence table that associates each set flow rate with the length of the open duration and the length of the closed duration. In this correspondence table, the length of the open duration and the closed duration are shortened in stages according to the size of the set flow rate. In this embodiment, the length of the open duration and the closed duration are the same, but they may be different lengths.

[0063] When the valve control unit 41 receives a set flow rate from the flow rate controller 3, it changes the open duration and the closed duration based on the received set flow rate and the correspondence table.

[0064] For example, as shown in FIG. 3 , a case will be described in which the set flow rate is set to 20% and then changed to 80% after a predetermined time has elapsed. In this case, the valve control unit 41 sets the open duration and closed duration for a set flow rate of 20%. When the liquid level in the tank 1 falls below the first liquid level, the valve control unit 41 repeats the open duration and closed duration for a set flow rate of 20% until the liquid level in the tank 1 reaches the first liquid level. When the liquid level in the tank 1 reaches the first liquid level, the valve control unit 41 closes the first opening / closing valve V1. Note that if the liquid level in the tank 1 falls below the first liquid level again after closing the first opening / closing valve V1, the valve control unit 41 repeats the open duration and closed duration for a set flow rate of 20% until the liquid level in the tank 1 reaches the first liquid level.

[0065] When the set flow rate is changed from 20% to 80%, the valve control unit 41 changes the open duration and closed duration from the set flow rate of 20% to the set flow rate of 80%. When the liquid level in the tank 1 falls below the first liquid level, the valve control unit 41 repeats the open duration and closed duration when the set flow rate is 80% until the liquid level in the tank 1 reaches the first liquid level. When the liquid level in the tank 1 reaches the first liquid level, the valve control unit 41 closes the first opening / closing valve V1. Note that if the liquid level in the tank 1 falls below the first liquid level again after closing the first opening / closing valve V1, the valve control unit 41 repeats the open duration and closed duration when the set flow rate is 80% until the liquid level in the tank 1 reaches the first liquid level.

[0066] Effect of First Embodiment According to the liquid material vaporizer 100 of the first embodiment, there is at least one closed duration while the liquid level in the tank 1 rises from below the first liquid level to the first liquid level, so the first on-off valve V1 is not always open, and the amount of liquid material supplied to the tank 1 per open duration can be reduced. As a result, the temperature drop and pressure fluctuations in the tank 1 can be more suppressed than in the past while the liquid level in the tank 1 rises from below the first liquid level to the first liquid level. In particular, in a liquid material vaporizer 100 without a preheater, the temperature of the liquid supplied to the tank 1 is lower than in a liquid material vaporizer having a preheater, making temperature drop and pressure fluctuations in the tank 1 more likely to occur. However, according to the liquid material vaporizer 100 of this embodiment, temperature drop and pressure fluctuations in the tank 1 can be suppressed even without a preheater.

[0067] In addition, the first opening / closing valve V1 is repeatedly opened and closed at least once during the time it takes for the liquid level in the tank 1 to rise from below the first liquid level to the first liquid level, thereby ensuring that the amount of liquid material supplied during each open period is reduced.

[0068] Furthermore, since the first opening / closing valve V1 is closed when the liquid level in the tank 1 reaches the first liquid level even if the open duration time has not elapsed, the required amount of liquid material can be reliably supplied to the tank 1, and more liquid material than necessary can be prevented from being supplied to the tank 1.

[0069] Furthermore, since pressure fluctuations within the tank 1 when supplying the liquid material to the tank 1 are suppressed, hunting of the flow rate output from the flow rate controller 3 can be prevented.

[0070] Furthermore, since the length of the open duration and the length of the closed duration are changed according to the set flow rate of the flow rate controller 3, hunting of the flow rate controller 3 can be reduced at each set flow rate.

[0071] Furthermore, even at a large set flow rate that makes the flow rate controller 3 prone to hunting, the open duration becomes shorter as the set flow rate increases, so hunting of the flow rate controller 3 can be suppressed while the liquid material is being supplied to the tank 1.

[0072] Second Embodiment of the Invention A liquid material vaporizing device according to a second embodiment of the present invention will be described below with reference to the drawings. Note that, hereinafter, only parts different from the first embodiment will be described, and the same members will be denoted by the same reference numerals.

[0073] The valve control unit 41 of the second embodiment differs from the valve control unit 41 of the first embodiment (which is configured to limit the open duration based on the liquid level in the tank 1) in that it adjusts the opening degree of the first opening / closing valve V1 in accordance with the set flow rate of the vaporized gas set in the flow rate controller 3, a flow rate sensor (not shown) provided in the flow rate controller 3, or a drive signal of a flow rate control valve (not shown) provided in the flow rate controller 3, regardless of the liquid level in the tank 1. The aspects of the flow rate sensor and the flow rate control valve are the same as those in the first embodiment.

[0074] The configuration of the valve control section 41 in the second embodiment will be described with reference to FIG.

[0075] First, the user sets a set flow rate and a threshold value for the set flow rate of the vaporized gas (S11). Here, the threshold value for the set flow rate can be, for example, 0%, but is not limited to this. If the set flow rate is set to a small flow rate, for example, 5%, the latent heat of vaporization in the tank 1 accompanying the discharge of the vaporized gas is small, so the temperature drop in the tank 1 is small and the pressure fluctuation in the tank 1 is small. Therefore, the threshold value for the set flow rate is not limited to 0%, and can be any small flow rate value.

[0076] The liquid material stored in the tank 1 is vaporized to generate vaporized gas, and while the vaporized gas flows through the gas outlet path R2, the flow control valve feedback-controls the flow rate of the vaporized gas based on the flow rate measured by the flow sensor and the set flow rate. In addition, the valve control unit 41 determines whether the set flow rate is equal to or greater than a threshold value (S12).

[0077] If the set flow rate is equal to or greater than the threshold value, the valve control unit 41 closes the first on-off valve V1 (S13) and returns to S12. As a result, the liquid material is not supplied into the tank 1, and therefore, no pressure fluctuations occur in the tank 1 due to the supply of the liquid material into the tank 1.

[0078] On the other hand, if the set flow rate is less than the threshold value, the valve control unit 41 determines whether the liquid level in the tank 1 is less than the first liquid level (S14). If the liquid level in the tank 1 is less than the first liquid level, the first opening / closing valve V1 is opened (S15) and the process returns to S12. This allows the liquid material to be supplied into the tank 1, preventing the liquid level in the tank 1 from dropping. On the other hand, if the liquid level in the tank 1 is equal to or greater than the first liquid level, the first opening / closing valve V1 is closed (S16) and the process returns to S12.

[0079] <Effects of the second embodiment> According to the liquid material vaporization device 100 of the second embodiment, the valve control unit 41 adjusts the valve opening depending on the set flow rate of the vaporized gas. Therefore, when the flow rate controller 3 is controlling the flow rate of the vaporized gas, it is possible to suppress pressure fluctuations in the tank 1 caused by supplying liquid material to the tank 1, and it is possible to suppress hunting of the flow rate output by the flow rate controller 3.

[0080] Furthermore, since the first on-off valve V1 is closed when the set flow rate is equal to or greater than the threshold value, it is possible to prevent pressure fluctuations in the tank 1 caused by supplying the liquid material to the tank 1. This makes it possible to further suppress hunting of the flow rate output by the flow rate controller 3. In particular, in the second embodiment, the threshold value is set to 0, so it is possible to reliably prevent pressure fluctuations in the tank 1 caused by supplying the liquid material to the tank 1.

[0081] In addition, if a blockage occurs in the gas discharge path R2, for example, the output of the flow rate sensor will become inaccurate. However, since the valve control unit 41 controls the opening and closing of the first opening / closing valve V1 based on the set flow rate of the vaporized gas, the flow rate of the vaporized gas can be controlled more accurately compared with the output of the flow rate sensor or the drive signal of the flow rate control valve.

[0082] Other Embodiments The present invention is not limited to the above-described embodiments.

[0083] In the first embodiment, the length of the open duration was greater than 0, but the length of the open duration may be 0 if the set flow rate is equal to or less than a predetermined value. For example, if the set flow rate is a small flow rate such as 5%, the drop in the liquid level in tank 1 is small, so if the liquid level in tank 1 is sufficient, it may not be necessary to supply liquid material to tank 1. In this case, by setting the length of the open duration to 0, hunting of the flow rate output by flow rate controller 3 can be completely suppressed.

[0084] In the first embodiment, the open duration and the closed duration are the same length, but the closed duration may be longer than the open duration. By keeping the first opening / closing valve V1 closed until the temperature drop and pressure fluctuation in the tank 1 that occur with one open duration converge, it is possible to prevent the temperature drop and pressure fluctuation in the tank 1 from increasing when the next open duration starts.

[0085] In the first embodiment, the opening degree of the first on-off valve V1 in the open state was 100%. However, the opening degree of the first on-off valve V1 in the open state may be adjustable between 0% and 100%. In this case, the valve control unit 41 limits the opening degree of the first on-off valve V1 in accordance with the set flow rate while the liquid level in the tank 1 increases from below the first liquid level to the first liquid level. Specifically, the valve control unit 41 acquires the set flow rate and gradually reduces the opening degree of the first on-off valve V1 as the set flow rate increases. This reduces the amount of liquid material supplied to the tank 1 during each open period compared to when the first on-off valve V1 is always open while the liquid level in the tank increases from below the first liquid level to the first liquid level.

[0086] In the first embodiment, the liquid material vaporization apparatus 100 is provided with the gas outlet path R2, the purge gas introduction path R3, the second on-off valve V2, the third on-off valve V3, and the flow rate controller 3, but the liquid material vaporization apparatus 100 does not necessarily have to be provided with the gas outlet path R2, the purge gas introduction path R3, the second on-off valve V2, the third on-off valve V3, and the flow rate controller 3.

[0087] In the first embodiment, the valve control unit 41 changes the length of the open duration and / or the length of the closed duration depending on the set flow rate, but the valve control unit 41 may also fix the length of the open duration and / or the length of the closed duration to a predetermined length regardless of the set flow rate.

[0088] In the first embodiment, the computer constituting the valve control unit 41 is housed inside the housing 5 , but the computer may be provided outside the housing 5 .

[0089] In the second embodiment, the valve control unit 41 adjusts the first opening / closing valve V1 by determining whether the set flow rate is equal to or greater than a predetermined threshold value, but this is not limiting. For example, the valve control unit 41 may adjust the first opening / closing valve V1 based on the flow rate measured by a flow rate sensor or a drive signal for a flow rate control valve.

[0090] Specifically, when the threshold value of the flow rate measured by the flow sensor or the threshold value of the drive signal of the flow control valve is set to a threshold value at which the flow rate of the vaporized gas is determined to be low, the valve control unit 41 determines whether the flow rate measured by the flow sensor or the drive signal of the flow control valve is equal to or greater than the threshold value. If the flow rate measured by the flow sensor or the drive signal of the flow control valve is equal to or greater than the threshold value, the valve control unit 41 closes the first opening / closing valve V1. On the other hand, if the flow rate measured by the flow sensor or the drive signal of the flow control valve is less than the threshold value, the valve control unit 41 opens the first opening / closing valve V1.

[0091] In the second embodiment, the liquid material vaporizing device 100 is configured to include the liquid level detecting unit 2, but the liquid level detecting unit 2 may not be included.

[0092] In addition, the present invention can be modified in various ways without departing from the spirit of the invention.

[0093] According to the present invention, it is possible to suppress a temperature drop and pressure fluctuation inside the tank when supplying a liquid material to the tank.

[0094] REFERENCE SIGNS LIST 100: Liquid material vaporizer 1: Tank 2: Liquid level detector 3: Flow rate controller 4: Control device 41: Valve controller R1: Supply path R2: Gas outlet path R3: Purge gas introduction path V1: First opening / closing valve

Claims

1. A liquid material vaporization device comprising: a tank for storing a liquid material and vaporizing the liquid material inside; a supply path for supplying the liquid material to the tank; a liquid level detection unit for detecting at least a first liquid level which is one of the liquid levels in the tank; a valve provided in the supply path for opening and closing the supply path; and a valve control unit for opening the valve to supply the liquid material to the tank when the liquid level in the tank is below the first liquid level, wherein the valve control unit provides a closed duration period during which the valve remains closed at least once during the time period from when the liquid level in the tank rises from below the first liquid level to the first liquid level.

2. The liquid material vaporization device described in claim 1, wherein the valve control unit repeats the closed duration and the open duration, which is the time during which the valve remains open, at least once during the time the liquid level in the tank changes from below the first liquid level to the first liquid level.

3. A liquid material vaporization device as described in claim 1 or 2, wherein the valve control unit closes the valve when the liquid level in the tank reaches the first liquid level before the open duration, which is the time during which the valve remains open, has elapsed.

4. A liquid material vaporization device as described in any one of claims 1 to 3, further comprising: a gas outlet path that discharges vaporized gas generated by vaporizing the liquid material from the tank; and a flow rate controller that controls the flow rate of the vaporized gas flowing through the gas outlet path.

5. A liquid material vaporization device as described in claim 4, wherein the valve control unit changes the length of the open duration, which is the time during which the valve remains open, and / or the length of the closed duration, depending on the set flow rate of the vaporized gas set in the flow rate controller.

6. The liquid material vaporizing device according to claim 5, wherein the valve control section shortens the duration of the open period as the set flow rate increases.

7. The liquid material vaporizing device according to claim 5 or 6, wherein the valve control section sets the open duration to zero when the set flow rate is equal to or less than a predetermined value.

8. A liquid material vaporizing device according to any one of claims 2 to 7, wherein the valve control section makes the duration of the closed state longer than the duration of the open state.

9. A method for controlling a liquid material vaporization device comprising: a tank for storing a liquid material and vaporizing the liquid material inside; a supply path for supplying the liquid material to the tank; a liquid level detection unit for detecting at least a first liquid level which is one of the liquid levels in the tank; and a valve provided in the supply path for opening and closing the supply path, wherein a closed duration period during which the valve remains closed is provided at least once during the time period from when the liquid level in the tank rises from below the first liquid level to when it reaches the first liquid level.

10. A control program for a liquid material vaporization device comprising: a tank for storing a liquid material in which the liquid material is vaporized; a supply path for supplying the liquid material to the tank; a liquid level detection unit for detecting at least a first liquid level which is one of the liquid levels in the tank; and a valve provided in the supply path for opening and closing the supply path, the control program causing a computer to function as a valve control unit by providing a closed duration period in which the valve remains closed at least once during the time period from when the liquid level in the tank rises from below the first liquid level to when it reaches the first liquid level.

11. A liquid material vaporization apparatus equipped with a flow rate controller that controls the flow rate of vaporized gas generated by vaporizing a liquid material, comprising: a tank that stores the liquid material and vaporizes it inside; a supply path that supplies the liquid material to the tank; a valve that is provided in the supply path and opens and closes the supply path; and a valve control unit that opens the valve to supply the liquid material to the tank, wherein the valve control unit adjusts the opening degree of the valve in accordance with the set flow rate of the vaporized gas set in the flow rate controller, a flow rate sensor provided in the flow rate controller, or a drive signal of a flow rate control valve provided in the flow rate controller.

12. A liquid material vaporization device as described in claim 11, wherein, when the vaporized gas is generated in the tank, the valve control unit closes the valve when the set flow rate is equal to or greater than a predetermined threshold, and opens the valve when the set flow rate is less than the threshold.

13. The liquid material vaporizer according to claim 12, wherein the threshold value is zero.

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