Vaporization device, film forming device, program recording medium and concentration control method

Abstract

Provided are a vaporization device, a film forming device, a program recording medium, and a concentration control method. The vaporization device includes a vaporization tank, a carrier gas supply path, a material gas derivation path, a concentration monitor, and a concentration control mechanism, wherein the concentration control mechanism includes: a concentration calculation unit that calculates the actual concentration of the material gas based on an output signal from the concentration monitor; a concentration control unit that performs a first control during the supply of the material gas so that the control value of the fluid control device constituting the concentration control mechanism becomes a preset initial setting value, and then performs a second control to feedback control in a manner such that the actual concentration approaches a preset target value by controlling the fluid control device; and a control switching unit that switches the control state of the concentration control unit from the first control to the second control based on the time-dependent change of the actual concentration after the concentration control unit starts the first control.

Description

Technical Field

[0001] The invention relates to a gasification device, a film forming device, a program recording medium and a concentration control method. Background Art

[0002] Conventionally, as a vaporization device for supplying material gas formed by vaporizing liquid or solid material to a chamber of a film-forming device in a semiconductor manufacturing process, etc., Patent document 1 describes that a carrier gas is intermittently supplied to a vaporization tank storing a material, material gas formed by vaporizing the material is intermittently discharged from the vaporization tank, and then a mixed gas obtained by diluting the discharged material gas with a dilution gas is supplied to the chamber.

[0003] It should be noted that in the conventional gasification device, the supply period of the material gas and the stop time of the supply are repeated to perform feedback control so that the actual concentration of the material gas contained in the mixed gas approaches a preset target value from the start of the supply period.

[0004] However, if feedback control is performed right after the start of the supply period as in the conventional gasification device, the fluid control device (specifically, a flow control device, a pressure control device, etc.) that is the control object or the distance between the gasification tank and the concentration monitor will cause a time delay, resulting in a problem of a significant overshoot in the concentration of the material gas right after the start of the supply period.

[0005] Prior art literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-224307 Summary of the invention

[0007] Technical issues

[0008] Here, a main subject of the present invention is to suppress an overshoot in the concentration of the material gas immediately after the start of the supply period.

[0009] Technical Solution

[0010] That is, the concentration control device of the present invention is characterized in that it is a vaporization device, comprising: a vaporization tank, which stores liquid or solid materials; a carrier gas supply path, which supplies carrier gas to the above-mentioned vaporization tank; a material gas outlet path, which circulates the material gas that is gasified and outlet from the above-mentioned vaporization tank; a concentration monitor, which is arranged on the above-mentioned material gas outlet path; a concentration control mechanism, which has a fluid control device for controlling the concentration of the material gas outlet from the above-mentioned material gas outlet path, the above-mentioned vaporization device repeatedly supplies and stops the above-mentioned material gas, and the above-mentioned concentration control mechanism has: a concentration calculation unit, which calculates the concentration of the material gas based on the concentration from the above-mentioned concentration monitoring unit. a concentration control unit which calculates the actual concentration of the material gas based on an output signal of the device; a concentration control unit which, during the supply period of the material gas, performs a first control in which a control value of a fluid control device constituting the concentration control mechanism becomes a preset initial setting value, and then performs a second control in which feedback control is performed in such a way that the actual concentration approaches a preset target value by controlling the fluid control device; and a control switching unit which switches the control state of the concentration control unit from the first control to the second control based on a temporal change in the actual concentration after the concentration control unit starts the first control.

[0011] Thus, during the supply period of the material gas, after the first control is performed to control the control value of the fluid control device constituting the concentration control mechanism to a preset initial setting value, the second control is performed to feedback control the actual concentration by controlling the fluid control device so that the actual concentration approaches the preset target value, and the first control is switched to the second control based on the temporal change of the actual concentration after the start of the first control, thereby suppressing overshoot after the start of the supply period compared to the case where the feedback control is performed after the start of the supply period like the conventional gasification device. It should be noted that the control value is the value of the control object of the fluid control device, and indicates the flow rate when the fluid control device is a flow control device, and indicates the pressure when the fluid control device is a pressure control device. In addition, the initial setting value refers to the setting value of the fluid control device at the start of the supply period.

[0012] As a specific implementation, it can be classified into a dilution type (flow type) and a pressure type. And, as an implementation of the dilution type, it can be cited that the above-mentioned gasification device also has a dilution gas supply path that merges with the above-mentioned material gas outlet path and supplies diluted gas to the material gas outlet path; the above-mentioned concentration control mechanism has a first flow control device arranged in the above-mentioned carrier gas supply path and a second flow control device arranged in the above-mentioned dilution gas supply path as the above-mentioned fluid control device; during the supply of the above-mentioned material gas, the above-mentioned concentration control unit performs a first control in a manner that controls the flow rate flowing through the above-mentioned first flow control device and the flow rate flowing through the above-mentioned second flow control device to respectively become a preset initial setting value, and then performs a second control in a manner that performs feedback control in a manner that controls at least one of the flow rate flowing through the above-mentioned first flow control device and the flow rate flowing through the above-mentioned second flow control device so that the above-mentioned actual concentration approaches a preset target value.

[0013] In addition, as a pressure-type implementation, the concentration control mechanism can be cited as the fluid control device; during the supply of the material gas, the concentration control unit performs a first control so that the flow rate through the flow control device and the pressure on the upstream side of the pressure control device become preset initial setting values, and then performs a second control in which feedback control is performed in a manner such that the actual concentration approaches a preset target value by controlling at least one of the flow rate through the flow control device and the pressure on the upstream side of the pressure control device.

[0014] Furthermore, as a specific embodiment of the control switching unit, it can be cited that the control switching unit switches the control state of the concentration control unit from the first control to the second control based on the rate of change of the actual concentration relative to the elapsed time after the start of the first control; in addition, as a more specific embodiment, it can be cited that the control switching unit switches the control state of the concentration control unit from the first control to the second control when the rate of change of the actual concentration is below a threshold value.

[0015] Furthermore, the control switching unit may switch the control state of the concentration control unit from the first control to the second control when the elapsed time before the actual concentration change rate becomes equal to or less than a threshold value exceeds a preset time.

[0016] Thus, even when the actual concentration change rate does not become less than the threshold value due to some important factors, the concentration of the material gas can be controlled because the first control is forcibly switched to the second control if the elapsed time exceeds the set time.

[0017] It should be noted that the gasification device may further include a threshold value setting unit that sets a threshold value based on a temporal change in the actual concentration after the first control is started. Specifically, the threshold value setting unit sets the threshold value based on a maximum value of a rate of change of the actual concentration relative to the elapsed time after the first control is started, or a rate of change of the actual concentration after a predetermined time has passed since the first control was started.

[0018] Thus, even when the actual concentration changes with time differently due to differences in the supplied material or the like, it is possible to switch from the first control to the second control at an appropriate time.

[0019] In this case, the threshold value setting unit may reset the threshold value for each supply period based on a temporal change in the actual concentration after the first control in the supply period is started.

[0020] Thus, even when the initial setting value of the fluid control device for each supply period is set based on the concentration change data indicating the time-dependent change of the actual concentration obtained during the previous supply period, the threshold value can be reset for each supply period. Thus, it is possible to switch from the first control to the second control at an appropriate time during each supply period.

[0021] In addition, immediately after the first control begins, the actual concentration changes with respect to the elapsed time and becomes unstable. Therefore, the control switching unit may set a predetermined delay time after the first control begins, and based on the time-dependent change of the actual concentration after the delay time, switch the control state of the concentration control unit from the first control to the second control. In this way, it is possible to suppress erroneous judgments that are likely to occur during the period when the actual concentration changes with respect to the elapsed time and becomes unstable.

[0022] In order to suppress the amount by which the actual concentration undershoots the target value, the gasification device may further include an initial value setting unit, which sets as the initial setting value a value obtained by multiplying a setting value determined so that the actual concentration becomes a predetermined target value by an overshoot gain greater than 1.

[0023] Furthermore, the film forming apparatus of the present invention includes the above-mentioned vaporization apparatus and a chamber for supplying the above-mentioned material gas.

[0024] In addition, the concentration control mechanism program of the present invention records the concentration control mechanism program used in the vaporization device, and the above-mentioned vaporization device includes: a vaporization tank, which stores liquid or solid materials; a carrier gas supply path, which supplies carrier gas to the above-mentioned vaporization tank; a material gas outlet path, which circulates the material gas that is gasified and outlet from the above-mentioned vaporization tank; a concentration monitor, which is arranged on the above-mentioned material gas outlet path; and a concentration control mechanism, which has a fluid control device for controlling the concentration of the material gas outlet from the above-mentioned material gas outlet path, the above-mentioned vaporization device repeatedly supplies and stops the above-mentioned material gas, and the above-mentioned concentration control mechanism program enables the computer to function as a concentration calculation unit, a concentration control unit, The concentration calculation unit calculates the actual concentration of the material gas based on the output signal from the concentration monitor; the concentration control unit performs a first control to control the control value of the fluid control device constituting the concentration control mechanism to a preset initial setting value during the supply of the material gas, and then performs a second control to feedback control the actual concentration by controlling the fluid control device so that the actual concentration approaches the preset target value; the control switching unit switches the control state of the concentration control unit from the first control to the second control based on the time-dependent change of the actual concentration after the concentration control unit starts the first control. It should be noted that the concentration control mechanism program can be sent electronically or recorded on a program recording medium such as a CD, DVD, BD, or flash memory.

[0025] In addition, the concentration control method of the present invention is used for a gasification device, and the gasification device includes: a gasification tank that stores liquid or solid materials; a carrier gas supply path that supplies carrier gas to the gasification tank; a material gas outlet path that flows the material gas that is gasified and outlet from the gasification tank; a concentration monitor that is arranged on the material gas outlet path; and a concentration control mechanism that includes a fluid control device that controls the concentration of the material gas outlet from the material gas outlet path, and the gasification device repeatedly supplies and stops the material gas. The concentration control method includes: a step of calculating the actual concentration of the material gas based on an output signal from the concentration monitor; a step of performing a first control during the supply of the material gas so that the control value of the fluid control device constituting the concentration control mechanism becomes a preset initial setting value, and then performing a second control in which feedback control is performed in such a way that the actual concentration approaches a preset target value by controlling the fluid control device; and a step of switching the control state of the concentration control unit from the first control to the second control based on the time change of the actual concentration after the concentration control unit starts the first control.

[0026] Technical Effects

[0027] According to the concentration control device configured in this manner, it is possible to suppress an overshoot in the concentration of the material gas immediately after the start of the supply period. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram showing a gasification device according to an embodiment.

[0029] Figure 2 This is a block diagram showing the function of the concentration control mechanism in the gasification device according to the embodiment.

[0030] Figure 3 This is a graph showing the change over time of the actual concentration when the supply and stop of the material gas are repeated by the vaporization device according to the embodiment.

[0031] Figure 4 This is a graph showing the change over time of the actual concentration when preliminary control is performed by the gasification device according to the embodiment.

[0032] Figure 5 This is a flowchart showing the operation of the gasification device according to the embodiment.

[0033] Figure 6 This is a graph showing the change over time of the actual concentration in a modification of the vaporization device according to the embodiment.

[0034] Figure 7 This is a schematic diagram showing a gasification device according to another embodiment.

[0035] Explanation of symbols

[0036] 100: Gasification device

[0037] 10: Gasification tank

[0038] L1: Carrier gas supply path

[0039] L2: Material gas extraction path

[0040] L3: Dilution gas supply path

[0041] 20: Switching mechanism

[0042] 30: Concentration control mechanism

[0043] MFC1: The first flow control device

[0044] MFC2: Secondary flow control device

[0045] C: Control Department

[0046] C1: Concentration calculation unit

[0047] C2: Target value storage unit

[0048] C3: Period determination unit

[0049] C4: Concentration Control Unit

[0050] C5: Concentration change data storage unit

[0051] C6: Control switch

[0052] C7: Threshold setting unit

[0053] C8: Threshold storage unit

[0054] C9: Setting time storage unit

[0055] C10: Initial value setting section

[0056] C11: Initial value storage

[0057] 40: Concentration monitor

[0058] PV: Pressure Control Equipment DETAILED DESCRIPTION

[0059] Hereinafter, the gasification device of the present invention will be described with reference to the drawings.

[0060] The vaporization device of the present invention is used, for example, to be built into a semiconductor production line to supply a gas of a predetermined concentration to a chamber used in a semiconductor manufacturing process. The vaporization device and the chamber together constitute a film forming device used in semiconductor manufacturing or the like.

[0061] The gasification device 100 of this embodiment is a so-called dilution type (flow type). Figure 1 As shown, it is provided with: a vaporization tank 10 for storing liquid or solid materials; a carrier gas supply path L1 for supplying a carrier gas to the above-mentioned vaporization tank 10; a material gas outlet path L2 for outleting the material gas after the material is vaporized from the vaporization tank 10; a dilution gas supply path L3 for supplying a dilution gas obtained by diluting the material gas to the material gas outlet path L2; a switching mechanism 20 for switching between supplying the material gas to the chamber CH and stopping the supply of the material gas; and a concentration control mechanism 30 for controlling the concentration of the material gas supplied to the chamber CH.

[0062] The carrier gas supply path L1 is provided with a first flow control device MFC1 for controlling the flow rate of the carrier gas. The first flow control device MFC1 is a mass flow controller having a flow control valve such as a thermal flow sensor, a piezoelectric valve, and a control circuit having a CPU and / or a memory, etc. The control circuit performs flow feedback control on the opening of the flow control valve based on the deviation between the set flow rate set by the control unit C described later and the measured flow rate measured by the flow sensor.

[0063] In the above-mentioned material gas outlet path L2, a concentration monitor 40 is provided at a position downstream of the confluence point with the dilution gas supply path L3. It should be noted that the concentration monitor 40 is used to measure the actual concentration of the material gas contained in the mixed gas formed by diluting the material gas with the dilution gas. The concentration monitor 40 of this embodiment uses the ratio of the pressure (partial pressure) of the material gas contained in the mixed gas to the pressure (total pressure) of the mixed gas to express the actual concentration (vol%) of the material gas contained in the mixed gas. Specifically, the concentration monitor 40 includes a pressure gauge 41 for measuring the total pressure and a pressure gauge 42 for measuring the partial pressure, for example, using a non-dispersive infrared absorption method.

[0064] The dilution gas supply path L3 is provided with a second flow control device MFC2 for controlling the flow rate of the dilution gas. The second flow control device MFC2 is, similarly to the first flow control device MFC1, a mass flow controller including, for example, a thermal flow sensor, a flow control valve such as a piezoelectric valve, and a control circuit including a CPU and / or a memory. The control circuit performs flow feedback control on the opening of the flow control valve based on the deviation between the set flow rate set by the control unit C described later and the measured flow rate measured by the flow sensor.

[0065] The switching mechanism 20 has a plurality of valves V1 to V3 that are opened and closed by receiving a valve switching signal. Thus, for example, the user opens and closes the valves V1 to V3 of the switching mechanism 20 at a preset timing, thereby repeating the supply and stop of the carrier gas to the vaporizer 10. As a result, the material gas is intermittently led out from the vaporizer 1 and intermittently supplied to the chamber CH. That is, in the vaporizer 100 of the present embodiment, the supply period of the material gas (specifically, the mixed gas) to the chamber CH and the stop period of stopping the supply are repeated.

[0066] Specifically, the switching mechanism 20 comprises: a detour flow path L4 connecting the carrier gas supply path L1 and the material gas outlet path L2; a first valve V1 arranged in the carrier gas supply path L1 at a position closer to the downstream side than the connection position of the detour flow path L4; a second valve V2 arranged in the material gas outlet path L2 at a position closer to the upstream side than the connection position with the detour flow path L4; and a third valve V3 arranged in the detour flow path L4.

[0067] The vaporizer 100 is in a supply period by opening the first valve V1 and the second valve V2 of the switching mechanism 20 and closing the third valve V3 , and is in a stop period by closing the first valve V1 and the second valve V2 of the switching mechanism 20 and opening the third valve V3 .

[0068] The concentration control mechanism 30 includes the first flow control device MFC1, the second flow control device MFC2, and a control unit C for controlling the first flow control device MFC1 and the second flow control device MFC2. That is, the fluid control devices of this embodiment are the first flow control device MFC1 and the second flow control device MFC2.

[0069] Specifically, the control unit C is a computer having a CPU, a memory, an AD converter, a DA converter, an input unit, etc., and the CPU executes a program stored in the memory, thereby Figure 2 As shown, it functions as a concentration calculation unit C1, a target value storage unit C2, a period determination unit C3, a concentration control unit C4, a concentration change data storage unit C5, a control switch unit C6, a threshold setting unit C7, a threshold storage unit C8, a set time storage unit C9, an initial value setting unit C10, an initial value storage unit C11, etc.

[0070] The concentration calculation unit C1 calculates the actual concentration of the material gas contained in the mixed gas based on the output signal output from the concentration monitor 40. Specifically, the output signals are obtained from the pressure gauge 41 and the pressure gauge 42, respectively, and the ratio of the partial pressure detected by the pressure gauge 42 to the total pressure detected by the pressure gauge 41 is calculated as the actual concentration (vol%) of the material gas contained in the mixed gas.

[0071] The target value storage unit C2 receives and stores a target value signal indicating a target concentration of the material gas supplied to the material gas supply destination (chamber CH) sent from other devices, for example, by a user input operation using an input unit such as a keyboard.

[0072] The period determination unit C3 receives the valve opening / closing signal and determines whether it is a supply period.

[0073] like Figure 3As shown, when the period determination unit C3 determines that the period is a supply period, the concentration control unit C4 obtains the initial setting value stored in the initial value storage unit C11 described later, and performs the first control in which the flow rate flowing through the first flow control device MFC1 and the flow rate flowing through the second flow control device MFC2 are controlled in such a manner that they become the initial setting values, respectively. Then, the concentration control unit C4 obtains the actual concentration signal output by the concentration calculation unit C1 and the target value signal stored in the target value storage unit C2, and performs the second control of feedback control in such a manner that the actual concentration approaches the target value by controlling at least one of the first flow control device MFC1 and the second flow control device MFC2. It should be noted that the feedback control is specifically PID control. Here, during the first control, the set flow rates of the first flow control device MFC1 and the second flow control device MFC2 as mass flow controllers are fixed at the initial setting value maintained at a constant flow value, for example, and the actual concentration calculated by the concentration calculation unit C1 is almost not fed back in real time with respect to each set flow rate. In contrast, in the second control, the actual concentration is almost fed back in real time with respect to each set flow rate, and the set flow rate is changed sequentially. In other words, in the first control, the concentration feedback loop for the first flow control device MFC1 and the second flow control device MFC2 is cut off, and in the second control, the concentration feedback loop for the first flow control device MFC1 and the second flow control device MFC2 is formed.

[0074] The concentration change data storage unit C5 acquires the actual concentration signal outputted from the concentration calculation unit C1 after the concentration control unit C4 starts the first control, and stores concentration change data indicating the temporal change of the actual concentration after the start of the first control.

[0075] The control switch unit C6 switches the control state of the concentration control unit C4 from the first control to the second control based on the concentration change data stored in the concentration change data storage unit C5. Specifically, the control switch unit C6 of the present embodiment switches the control state of the concentration control unit C4 from the first control to the second control when the rate of change of the actual concentration relative to the elapsed time after the start of the first control is below a threshold. More specifically, the control switch unit C6 of the present embodiment is configured to output a switching signal to the concentration control unit C4 in such a way that the control state of the concentration control unit C4 is switched from the first control to the second control when the rate of change of the actual concentration is below a threshold before the elapsed time after the start of the first control exceeds a set time, or when the elapsed time before the rate of change of the actual concentration is below a threshold becomes above a set time.

[0076] The above-mentioned threshold is set by the threshold setting unit C7 and stored in the threshold storage unit C8. Specifically, the threshold setting unit C7 sets the threshold based on the concentration change data obtained when the concentration control unit C4 performs the first control. It should be noted that the threshold setting unit C7 of the present embodiment sets the threshold based on the concentration change data obtained during the supply period when the period determination unit C3 determines that the period is a supply period. That is, the threshold setting unit C7 sets the threshold for each supply period. More specifically, when the period determination unit C3 determines that the period is a supply period, the threshold setting unit C7 obtains the concentration change data obtained during the supply period from the concentration change data storage unit C5 at any time (in real time), and sets the threshold based on the concentration change data.

[0077] Next, a method of setting a threshold value by the threshold value setting unit C7 will be described by way of example.

[0078] As a first method, the threshold setting unit C7 is set to calculate the rate of change of the actual concentration after a predetermined time has passed from the start of the first control based on the acquired concentration change data, and calculate the threshold based on the rate of change of the actual concentration. Specifically, the threshold setting unit C7 is set to calculate the rate of change of the actual concentration after a predetermined period has passed after the start of the first control at any time based on the acquired concentration change data, and calculate the threshold based on the rate of change of the actual concentration during the period corresponding to the predetermined time has passed from the start of the first control. More specifically, it is set to calculate the threshold based on the rate of change of the actual concentration during the initial period from the start of the first control. In this case, the threshold setting unit C7 sets the value of 1 / N (N is an arbitrary value greater than 1) of the rate of change of the actual concentration as the threshold. Here, the predetermined period, for example, the control cycle is 1 second. In the case of calculating the rate of change for 5 seconds, it can be a partially overlapping period such as 0 to 5 seconds, 1 to 6 seconds, 2 to 7 seconds...

[0079] As a second method, the threshold setting unit C7 is set to calculate the maximum value of the rate of change of the actual concentration after the start of the first control based on the acquired concentration change data, and calculate the threshold value based on the maximum value of the rate of change of the actual concentration. Specifically, the threshold setting unit C7 is set to calculate the rate of change of the actual concentration after a predetermined time has passed since the start of the first control based on the acquired concentration change data, and calculate the threshold value based on the maximum value of the rate of change of the actual concentration selected therefrom. For example, the threshold setting unit C7 can calculate the rate of change of the actual concentration at any time during a predetermined period, and select the maximum value by storing it while updating its peak value. In this case, the threshold setting unit C7 sets the value of 1 / N (N is an arbitrary value greater than 1) of the maximum value of the rate of change of the actual concentration as the threshold.

[0080] Here, the above actual concentration change rate is further described in detail. Figure 3(a) A portion of the diagram shown is enlarged Figure 3 As shown in (b), the rate of change of the actual concentration is the slope of the straight line X connecting the actual concentration at the start and end of the predetermined period △T, and when the actual concentration is set to f(t) and the elapsed time is set to t, it is a value calculated by (f(t)-f(t-△T)) / △T. That is, the rate of change of the actual concentration can also be said to be the amount of change of the actual concentration per unit time. In addition, the rate of change of the actual concentration can be calculated by using the least squares fitting to obtain an approximate straight line for the concentration change data of the predetermined period instead of the straight line connecting the start and end of the predetermined period, and the slope of the approximate straight line.

[0081] That is, in this embodiment, within one supply period, a threshold is set based on the concentration change data obtained in the first control during the supply period, and the first control during the supply period is switched to the second control based on the threshold.

[0082] It should be noted that in this embodiment, the threshold setting unit C7 is provided so that the threshold is reset in each supply period. However, the threshold setting unit C7 may not be provided, and a pre-set threshold may be stored in the threshold storage unit C8, and the threshold may be used for control in any supply period.

[0083] In this case, the threshold value may be obtained based on preliminary concentration change data obtained by preliminary control (see Figure 4 ), calculated in advance using any of the above methods, the pre-control is to make the flow rate flowing through the first flow control device MFC1 and the flow rate flowing through the second flow control device MFC2 become preset values ​​before the gasifier 100 is shipped out of the factory. In addition, it can also be calculated based on the preliminary concentration change data obtained by performing the above pre-control after the gasifier 100 is assembled to the production line, etc. In addition, it can also be calculated based on the preliminary concentration change data obtained by performing pre-control during the first supply period of the material gas to the chamber CH through the gasifier 100. It should be noted that, as Figure 4 As shown, when the flow rate through the first flow control device MFC1 and the flow rate through the second flow control device MFC2 are controlled in a manner such that they become preset values, it is preferred to set the preset values ​​in a manner such that the peak value of the actual concentration reaches the target value or the vicinity of the target value. It should be noted that the N value in the above-mentioned first method or the above-mentioned second method can be determined based on the above-mentioned preliminary concentration change data.

[0084] The above-mentioned set time is stored in the set time storage unit C9. It should be noted that the set time storage unit C9 receives and stores, for example, a user input operation based on an input unit such as a keyboard and / or a set time signal sent by other devices. It should be noted that the set time is preferably set to the time obtained by adding an appropriate margin to the time when the actual concentration in the above-mentioned preliminary concentration change data reaches the peak value.

[0085] The initial value setting unit C10 is set to obtain the concentration change data obtained during the last supply period stored in the concentration change data storage unit C5 when the period determination unit C3 determines that it is a stop period, and calculate the initial setting values ​​of the first flow control device MFC1 and the second flow control device MFC2 during the next supply period based on the concentration change data. It should be noted that the initial setting value can be the same value in the first flow control device MFC1 and the second flow control device MFC2, or different values. Specifically, when the initial setting value is the set flow rate Qc and Qd set in the first flow control device MFC1 and the second flow control device MFC2 and the flow rates of the carrier gas and the dilution gas are kept constant, the actual concentration measured by the concentration monitor 40 is set to the target concentration stored in the target value storage unit C2. For example, when the actual concentration at the end of the first control is greater than the target concentration, the set flow rate Qc of the carrier gas used during the next supply period is set to a value smaller than the value of this time. On the contrary, when the actual concentration at the end of the first control is less than the target concentration, the set flow rate Qd of the carrier gas used during the next supply period is set to a value larger than the value of this time.

[0086] The initial value storage unit C11 receives and stores the initial setting value signal from the initial value setting unit C10. Specifically, each time the initial value storage unit C11 receives the initial setting value signal from the initial value setting unit C10, it overwrites and stores the initial setting value. Here, since the initial value setting unit C10 sets the initial setting value based on the concentration change data obtained during the last supply period, the initial setting value cannot be set for the initial supply period. Therefore, the initial setting values ​​of the first flow control device MFC1 and the second flow control device MFC2 for the initial supply period are stored in advance in the initial value storage unit C11. It should be noted that the initial setting value can be set based on the above-mentioned preliminary concentration change data.

[0087] It should be noted that in the present embodiment, the initial value setting unit C10 is provided so that the initial setting value is reset in each supply period. However, the initial value setting unit C10 may not be provided, but a pre-set initial setting value (e.g., the most initial setting value) may be stored in the initial value storage unit C11, and the initial setting value may be used for control in any supply period.

[0088] Next, based on Figure 5 The operation of the gasification device 100 will be described.

[0089] First, when the operation of the vaporizer 100 is started, the period determination unit C3 determines whether it is a supply period. In the present embodiment, the period determination unit C3 acquires a valve switching signal and determines whether it is a supply period based on the signal (step S1).

[0090] Then, when the period determination unit C3 determines that it is not a supply period, in other words, when it is determined that it is a stop period, the initial value setting unit C10 sets a new initial setting value based on the concentration change data of the supply period before the stop period, if the concentration change data storage unit C5 stores the concentration change data, and stores it in the initial value storage unit C11. Then, the concentration control unit C4 sets the latest initial setting value stored in the initial value storage unit C11 as the setting value of the first flow control device MFC1 and the setting value of the second flow control device MFC2 (step S2).

[0091] On the other hand, when the period determination unit C3 determines that it is the supply period, the concentration control unit C4 determines whether the control state is the second control (step S3). Then, when the concentration control unit C4 determines that the control state is not the second control, the first control is performed so that the flow rate flowing through the first flow control device MFC1 and the flow rate flowing through the second flow control device MFC2 become the set initial setting values ​​(step S4).

[0092] Then, if the first control is started by the concentration control unit C4, the concentration change data storage unit C5 sequentially stores the concentration change data indicating the time-dependent change of the actual concentration after the start of the first control. In addition, the threshold setting unit C7 sets the threshold value based on the concentration change data stored in the concentration change data storage unit C5 at any time and stores it in the threshold storage unit C8. In addition, the control switch unit C6 refers to the concentration change data sequentially stored in the concentration change data storage unit C5 to determine whether the rate of change of the actual concentration relative to the elapsed time after the start of the first control is less than the threshold value set by the threshold setting unit C7 (step S5), and then determines whether the elapsed time is more than the set time (step S6).

[0093] That is, in this embodiment, the threshold setting unit C7 sets the threshold value based on the concentration change data obtained during each supply period, and the control switch unit C6 determines the switching time using the concentration change data obtained during the supply period and the threshold value.

[0094] Then, when it is determined that the actual concentration change rate is below the threshold value, or when it is determined that the elapsed time is above the set time, the control switch unit C6 sends a control state switching signal to the concentration control unit C4. As a result, the concentration control unit C4 switches the control state from the first control to the second control and starts the second control (step S7).

[0095] It should be noted that, when it is determined in step S3 that the control state is the second control, the concentration control unit C4 continues the second control (step S8).

[0096] Thereafter, the gasification device 100 determines whether a control end signal is received (step S9 ), and repeats steps S1 to S8 until the control end signal is received, and ends the operation when the control end signal is received.

[0097] According to the gasification device 100 of the present embodiment constructed in this way, after the supply period just starts, the first control of maintaining the flow rate flowing through the first flow control device MFC1 and the flow rate flowing through the second flow control device MFC2 at the initial set values ​​is performed to increase the actual concentration. After the actual concentration increases to a certain level, the second control is switched to perform feedback control in a manner of controlling the first flow control device MFC1 and the second flow control device MFC2 so that the actual concentration approaches the target concentration, thereby suppressing the overshoot of the concentration of the material gas just after the supply period just starts.

[0098] A modified example of this embodiment is described. For the initial setting value Qc set in the first flow control device MFC1 in the first control, as shown in FIG. Figure 3 and Figure 4 As shown in the graph, at the end of the first control, the actual concentration measured by the concentration monitor 40 is determined to be almost the same as the target value, but the actual concentration can also be set to exceed the target value by an allowable amount. That is, the initial value setting unit C10 can be formed by multiplying the set flow rate Qc of the carrier gas that makes the actual concentration the target value by the overshoot gain Go as the initial setting value and setting it in the first flow control device MFC. Here, the overshoot gain Go is set to a value such as 1.1 to 1.2. In this way, Figure 6 As shown in the graph, the undershoot that occurs after the overshoot can be suppressed, and once the actual concentration exceeds the target value, the value is almost never lower than the target value.

[0099] <Another embodiment>

[0100] The gasification device 100 of the above embodiment is a dilution type (flow type), but it can also be a pressure type. Figure 7As shown, the pressure-type gasification device 100 does not have a dilution gas supply path L3 compared to the dilution-type gasification device 100 of the above-mentioned embodiment, but instead has a pressure control device PV at a position downstream of the concentration monitor 40 of the material gas outlet path L2. That is, the fluid control device of this embodiment is the flow control device MFC1 and the pressure control device PV.

[0101] In the pressure-type gasification device 100, the initial value storage unit C11 may store the initial setting values ​​of the flow rate flowing through the first flow control device MFC1 and the pressure on the upstream side of the pressure control device PV, and the concentration control unit C4 may perform a first control during the supply period to control the pressure on the upstream side of the pressure control device PV (specifically, the pressure of the pressure gauge 41) and the flow rate flowing through the first flow control device MFC1 to the initial setting values, and then perform a second control to perform feedback control in a manner that controls at least one of the first flow control device MFC1 and the pressure control device PV so that the actual concentration approaches the target value. It should be noted that the pressure control device PV is specifically a pressure regulating valve, and the concentration control unit C4 may be configured to control the valve opening of the pressure regulating valve.

[0102] It should be noted that even in the pressure-type vaporizer 100, if feedback control is performed so that the actual concentration approaches the target value after the start of the supply period, there is a problem that the concentration of the material gas overshoots significantly after the start of the supply period due to the time delay of the change of the total pressure of the vaporizer tank caused by the flow rate of the carrier gas flowing into the vaporizer tank. However, according to the pressure-type vaporizer 100 of the present invention, it is possible to suppress the overshoot of the concentration of the material gas after the start of the supply period.

[0103] In addition, in the above-mentioned embodiment, the switching time from the first control to the second control is determined based on the rate of change of the actual concentration relative to the elapsed time after the start of the first control, but it can also be configured to determine the switching time from the first control to the second control based on the rate of change of the rate of change of the actual concentration (the second-order differential of the actual concentration waveform).

[0104] In addition, immediately after the first control starts, in other words, immediately after the supply period starts, the change in actual concentration relative to the elapsed time becomes unstable. Therefore, the control switch unit C6 may be configured to set a delay time after the first control starts, and determine whether the rate of change of the actual concentration relative to the elapsed time after the delay time is below a threshold value. Thus, it is possible to suppress the occurrence of erroneous determinations that are likely to occur during the period when the change in actual concentration relative to the elapsed time becomes unstable.

[0105] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

Claims

1. A gasification device, characterized in that: have: A vaporization tank storing liquid or solid materials; a carrier gas supply path supplying carrier gas to the vaporization tank; a material gas outlet path flowing material gas that vaporizes the material and is then outlet from the vaporization tank; a concentration monitor disposed on the material gas outlet path; and a concentration control mechanism including a fluid control device for controlling the concentration of the material gas extracted from the material gas extraction path, wherein the gasification device repeatedly supplies and stops the material gas, The concentration control mechanism comprises: a concentration calculation section that calculates an actual concentration of the material gas based on an output signal from the concentration monitor; a concentration control unit that performs a first control to control a control value of a fluid control device constituting the concentration control mechanism to a preset initial setting value during the supply of the material gas, and then performs a second control to perform feedback control to control the fluid control device so that the actual concentration approaches a preset target value; as well as A control switching unit calculates a time-dependent change amount of the actual concentration after the concentration control unit starts the first control, and switches a control state of the concentration control unit from the first control to the second control based on the calculated time-dependent change amount.

2. The gasification device according to claim 1, characterized in that: The vaporization device further includes a dilution gas supply path, the dilution gas supply path merges with the material gas outlet path and supplies the dilution gas to the material gas outlet path. The concentration control mechanism includes a first flow rate control device provided in the carrier gas supply path and a second flow rate control device provided in the dilution gas supply path as the fluid control device. During the supply of the material gas, the concentration control unit performs a first control in which the flow rates flowing through the first flow control device and the flow rates flowing through the second flow control device are controlled to respectively become preset initial setting values, and then performs a second control in which feedback control is performed in which the actual concentration approaches a preset target value by controlling at least one of the flow rates flowing through the first flow control device and the flow rates flowing through the second flow control device.

3. The gasification device according to claim 1, characterized in that: The concentration control mechanism includes a flow control device provided in the carrier gas supply path and a pressure control device provided at a position downstream of the concentration monitor in the material gas outlet path as the fluid control device. During the supply of the material gas, the concentration control unit performs a first control so that the flow rate flowing through the flow control device and the pressure on the upstream side of the pressure control device become preset initial setting values, respectively, and then performs a second control in a manner that feedback control is performed so that the actual concentration approaches a preset target value by controlling at least one of the flow rate flowing through the flow control device and the pressure on the upstream side of the pressure control device.

4. The gasification device according to claim 1, characterized in that: The control switching unit switches the control state of the concentration control unit from the first control to the second control based on a rate of change of the actual concentration with respect to an elapsed time after the start of the first control.

5. The gasification device according to claim 4, characterized in that: The control switching unit switches the control state of the concentration control unit from the first control to the second control when the rate of change of the actual concentration is equal to or smaller than a threshold value.

6. The gasification device according to claim 5, characterized in that: The control switching unit switches the control state of the concentration control unit from the first control to the second control when the elapsed time before the actual concentration change rate becomes equal to or less than a threshold value exceeds a preset time.

7. The gasification device according to claim 5, characterized in that: The vaporization device further includes a threshold setting unit configured to set a threshold based on a temporal change in the actual concentration after the first control by the concentration control unit is started.

8. The gasification device according to claim 7, characterized in that: The threshold setting unit sets the threshold based on a maximum value of the rate of change of the actual concentration after the start of the first control or a rate of change of the actual concentration at a time when a predetermined time has elapsed after the start of the first control.

9. The gasification device according to claim 7, characterized in that: The threshold value setting unit resets the threshold value for each supply period based on a temporal change in the actual concentration after the first control is started in the supply period.

10. The gasification device according to claim 1, characterized in that: The control switching unit provides a predetermined delay time after the start of the first control, and switches the control state of the concentration control unit from the first control to the second control based on a temporal change in the actual concentration after the delay time.

11. The gasification device according to claim 1, characterized in that: The vaporization device further includes an initial value setting unit that sets, as the initial setting value, a value obtained by multiplying a setting value determined so that the actual concentration becomes a predetermined target value by an overshoot gain of 1 or more.

12. A film forming device, characterized in that: have: The gasification device according to claim 1; and A chamber is provided to supply the material gas.

13. A program recording medium recording a concentration control mechanism program, characterized in that: A program for recording a concentration control mechanism used in a vaporizer, the vaporizer having: a vaporizer tank storing a liquid or solid material; a carrier gas supply path supplying a carrier gas to the vaporizer tank; a material gas outlet path flowing a material gas that is vaporized and then outlet from the vaporizer tank; and a concentration monitor disposed in the material gas outlet path; and a concentration control mechanism including a fluid control device for controlling the concentration of the material gas extracted from the material gas extraction path, wherein the gasification device repeatedly supplies and stops the material gas, The concentration control means uses a program to make the computer function as a concentration calculation unit, a concentration control unit, and a control switching unit. The concentration calculation section calculates the actual concentration of the material gas based on the output signal from the concentration monitor, The concentration control unit performs a first control during the supply of the material gas so that the control value of the fluid control device constituting the concentration control mechanism becomes a preset initial setting value, and then performs a second control to perform feedback control so that the actual concentration approaches a preset target value by controlling the fluid control device. The control switching unit switches a control state of the concentration control unit from the first control to the second control based on a temporal change in the actual concentration after the concentration control unit starts the first control.

14. A concentration control method, characterized in that: Used in a gasification device, the gasification device comprises: a gasification tank storing liquid or solid materials; a carrier gas supply path supplying carrier gas to the gasification tank; a material gas outlet path flowing material gas that is gasified and then outlet from the gasification tank; a concentration monitor disposed on the material gas outlet path; and a concentration control mechanism including a fluid control device for controlling the concentration of the material gas extracted from the material gas extraction path, wherein the gasification device repeatedly supplies and stops the material gas, The concentration control method comprises: a step of calculating the actual concentration of the material gas based on an output signal from the concentration monitor; After performing a first control to control a control value of a fluid control device constituting the concentration control mechanism to a preset initial setting value during the supply of the material gas, a second control to perform feedback control to control the fluid control device so that the actual concentration approaches a preset target value; and A step of switching a control state of the concentration control unit from the first control to the second control based on a temporal change in the actual concentration after the concentration control unit starts the first control.

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