Raw material gasification system, concentration control module for the same, concentration control method and concentration control program

Abstract

This invention suppresses overshoot in the concentration of raw material gas when switching from the self-circulating action to the raw material gas generation action. This invention is a concentration control module for a raw material gasification device that performs the raw material gas generation action and the circulating action. The raw material gas generation action introduces carrier gas into a storage tank containing raw material, and the raw material is gasified and discharged by bubbling. The circulating action causes the carrier gas to flow in a bypass passage and bypass the storage tank. The concentration control module performs concentration control in the raw material gas generation action and pressure control in the circulating action.

Description

[Technical Field]

[0001] The present invention relates to a raw material gasification system for introducing a carrier gas into a liquid or solid raw material for gasification and supplying the raw material gas generated therefrom, a concentration control module for the system, a concentration control method and a concentration control program. [Previous Technology]

[0002] As shown in Patent Document 1, such a raw material gasification system includes: a tank containing raw material; an inlet pipe for introducing carrier gas into the tank to gasify the raw material; and an outlet pipe for discharging a mixture of carrier gas and raw material gas formed by gasification of raw material from the tank.

[0003] Furthermore, the outlet pipe is equipped with a concentration measuring unit for measuring the concentration of the raw material gas and a control valve. In addition, the control valve on the outlet pipe is controlled by using the measured concentration obtained from the concentration measuring unit as a set concentration, thereby controlling the concentration of the raw material gas. Furthermore, the control valve is controlled by a valve control unit. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2013-145887 [Summary of the Invention]

[0005] [Problem to be solved by the invention] In the aforementioned raw material gasification system, a purge line is connected to the inlet pipe and the outlet pipe, which is a bypass pipe that bypasses the storage tank. Furthermore, the inlet pipe, the outlet pipe, and the bypass pipe are equipped with on / off valves that switch the flow path of the carrier gas through the storage tank and the flow path through the bypass pipe.

[0006] In addition, in the raw material gasification system, it is conceivable to use the raw material gas generation action and the bypass action by controlling the opening and closing valve, for example, periodically switching the raw material gas generation action to introduce carrier gas into the storage tank, and to gasify the raw material and export the raw material gas by bubbling, and the bypass action to make the carrier gas flow in the bypass passage and bypass the storage tank.

[0007] However, when concentration control is performed as described above, if the operation switches from generating the raw material gas to rotating, the carrier gas flows in the outlet pipe, and the control valve is controlled by the valve control, resulting in a fully open state. Then, if the operation switches from rotating to generating the raw material gas, since the control valve is fully open, the overshoot of the raw material gas concentration increases immediately after switching to generating the raw material gas.

[0008] Therefore, the present invention has been made in view of the problems described above, and its main objective is to suppress the overshoot of the feed gas concentration that occurs immediately after the self-rotating action switches to the feed gas generation action. [Means for Solving the Problem]

[0009] That is, the concentration control module of the present invention is used in a raw material gasification system for performing raw material gas generation and bypassing actions. The raw material gas generation action introduces carrier gas into a storage tank containing raw materials, and the raw materials are gasified and the raw material gas is discharged by bubbling. The bypassing action causes the carrier gas to flow in a bypass passage and bypass the storage tank. The concentration control module is characterized in that it performs concentration control in the raw material gas generation action and pressure control in the bypassing action.

[0010] If this is the concentration control module, the concentration control is performed during the raw material gas generation action and the pressure control is performed during the circling action. Therefore, the overshoot of the raw material gas concentration that occurs immediately after the circling action switches to the raw material gas generation action can be suppressed.

[0011] In order to determine whether a feed gas generation operation or a bypass operation is occurring without acquiring operation information from the feed gasification system (indicating whether the operation is feed gas generation or bypass operation), the concentration control module ideally includes: a determination unit that determines whether the carrier gas is flowing in the bypass passage; and a control unit that switches between concentration control and pressure control based on the determination result of the determination unit. According to this structure, the concentration control module does not require a communication device to acquire operation information from the feed gasification system (indicating whether the operation is feed gas generation or bypass operation).

[0012] As a specific embodiment of the determination unit, the determination unit is ideally designed to determine whether the carrier gas flows in the bypass passage based on the concentration or partial pressure of the raw material gas.

[0013] In the determination method of the determination unit, as a specific implementation example, it is ideal for the determination unit to determine whether the carrier gas flows in the bypass passage by using the ratio of the set concentration relative to the raw material gas or a preset fixed value as the threshold value.

[0014] As a specific implementation of pressure control, it is ideal for the control unit to use a pre-set fixed value or the pressure of the mixture of the raw material gas and the carrier gas during the raw material gas generation operation as the set pressure in the pressure control.

[0015] If the control unit switches from pressure control to concentration control immediately after switching from the self-circulating action to the raw material gas generation action, the concentration of the raw material gas will overshoot. In order to suppress this overshoot, the control unit is preferably configured to switch to concentration control after a predetermined time has elapsed since switching from the pressure control to the concentration control.

[0016] Moreover, the raw material gasification system of the present invention is characterized by comprising: a storage tank containing liquid or solid raw materials; an inlet pipe for introducing carrier gas into the storage tank for bubbling; an outlet pipe for discharging a mixture of the carrier gas and the raw material gas formed by gasification of the raw materials from the storage tank; and a concentration control module as described in any one of technical solutions 1 to 6, disposed in the outlet pipe.

[0017] Furthermore, the concentration control method of the present invention is a concentration control method for a raw material gasification system that performs a raw material gas generation action and a bypass action. The raw material gas generation action introduces carrier gas into a storage tank containing raw material, and the raw material is gasified and the raw material gas is discharged by bubbling. The bypass action causes the carrier gas to flow in a bypass passage and bypass the storage tank. The concentration control method is characterized in that concentration control is performed in the raw material gas generation action and pressure control is performed in the bypass action.

[0018] Furthermore, the concentration control program of the present invention is a concentration control program for a raw material gasification system that performs a raw material gas generation operation and a bypass operation. The raw material gas generation operation introduces carrier gas into a storage tank containing raw materials, vaporizes the raw materials by bubbling, and discharges the raw material gas. The bypass operation causes the carrier gas to flow through a bypass passage and bypass the storage tank. The concentration control program is characterized in that concentration control is performed by a computer during the raw material gas generation operation, and pressure control is performed by the computer during the bypass operation. [Effects of the Invention]

[0019] According to the present invention described above, the overshoot of the concentration of the raw material gas can be suppressed after the self-rotating action is switched to the raw material gas generation action.

Implementation Method

[0021] Hereinafter, a feed gasification system according to an embodiment of the present invention will be described with reference to the drawings.

[0022] <1. System Structure> The raw material gasification system 100 of this embodiment is used, for example, in a semiconductor manufacturing process, to supply raw material gases such as isopropanol (IPA) to the drying chamber of a wafer cleaning apparatus at a predetermined concentration. Furthermore, the raw material gasification system can also supply raw material gases at a predetermined concentration to the processing chamber of a semiconductor processing apparatus such as a chemical vapor deposition (CVD) apparatus or a metal-organic chemical vapor deposition (MOCVD) apparatus.

[0023] The raw material gasification system 100 introduces a carrier gas into a liquid or solid raw material for gasification and supplies the resulting raw material gas. Furthermore, the following description uses an example of using a liquid raw material, but the same applies when using a solid raw material.

[0024] Specifically, the raw material gasification system 100, as shown in Figure 1, includes: a storage tank 2 containing liquid raw material LM; an inlet pipe 3 for introducing carrier gas CG into the storage tank 2 for bubbling; and an outlet pipe 4 for outleting a mixture of carrier gas CG and raw material gas MG formed by gasification of raw material LM from the storage tank 2.

[0025] The storage tank 2 is a closed container, for example made of stainless steel, for containing liquid raw material LM, and is maintained at a certain temperature by a heating mechanism such as a heater or a cooling mechanism located externally.

[0026] Upstream of the inlet pipe 3, for example, a supply source (not shown) of a carrier gas CG such as nitrogen or hydrogen is connected, and downstream of the inlet pipe 3 extends into the storage tank 2. The downstream opening of the inlet pipe 3 is positioned lower than the liquid level of the raw material LM contained in the liquid in the storage tank 2, and the raw material LM is bubbled by the carrier gas CG introduced from the inlet pipe 3 into the storage tank 2. Furthermore, a mass flow controller 5 is provided in the inlet pipe 3, which is used to maintain a constant flow rate of the carrier gas CG supplied to the storage tank 2.

[0027] The upstream opening of the outlet pipe 4 is connected to the upper space (gas phase) formed in the storage tank 2 in a state where liquid raw material LM is contained. Furthermore, the processing chamber 200 of the semiconductor processing device is connected to the downstream side of the outlet pipe 4. Moreover, a concentration control module 6 is provided in the outlet pipe 4, which is used to control the concentration of the raw material gas in the mixed gas MG.

[0028] Furthermore, a bypass pipe BP is connected to the inlet pipe 3 and the outlet pipe 4 to serve as a bypass passage around the storage tank 2 (bypass). Moreover, flow path switching valves V1 to V3 are provided in the inlet pipe 3, the outlet pipe 4 and the bypass pipe BP to switch the flow path of the carrier gas CG through the storage tank 2 and the flow path through the bypass pipe BP. By controlling the opening and closing of these flow path switching valves V1 to V3, the (1) raw material gas generation operation (raw material gas generation state) and the (2) bypass operation (bypass state) are switched. The (1) raw material gas generation operation (raw material gas generation state) introduces the carrier gas CG into the storage tank 2 containing the raw material LM, and the raw material LM is vaporized and the raw material gas is discharged by bubbling. The (2) bypass operation (bypass state) causes the carrier gas CG to flow in the bypass pipe BP and bypass the storage tank 2.

[0029] <2. Concentration Control Module> Next, the concentration control module 6 of this embodiment will be described.

[0030] As shown in Figure 1, the concentration control module 6 includes: a concentration measuring unit 61, which measures the concentration of the raw material gas flowing in the outlet pipe 4; a control valve 62, which is provided in the outlet pipe 4 that discharges the raw material gas from the storage tank 2; and a control machine 63, which performs feedback control on the control valve 62 based on the concentration measured by the concentration measuring unit 61.

[0031] In this embodiment, a pressure measuring unit 64 for measuring the pressure (total pressure) inside the storage tank 2 is provided in the outlet pipe 4 upstream of the control valve 62. Furthermore, the pressure measuring unit 64 can also be installed separately from the concentration control module 6.

[0032] The concentration measuring unit 61 continuously measures the concentration of the raw material gas in the mixed gas MG. It can use an NDIR sensor that utilizes non-dispersive infrared (NDIR) absorption, or an ultrasonic sensor that uses changes in the speed of sound due to changes in the concentration of the raw material gas. Furthermore, the concentration measuring unit 61 can also continuously measure the partial pressure of the raw material gas in the mixed gas MG, and use the total pressure of the mixed gas MG obtained by the pressure measuring unit 64 to measure the concentration of the raw material gas.

[0033] The control valve 62 is located in the outlet pipe 4 on the downstream side of the concentration measuring section 61, and its opening degree is controlled by the control machine 63.

[0034] The control machine 63 is a computer including a central processing unit (CPU), memory, an analog-to-digital (A / D) converter, an input / output interface, etc. By having these parts cooperate based on the program stored in memory, it performs the functions of a decision unit 63a, a valve control unit 63b, a setting acceptance unit 63c, etc., as shown in FIG2.

[0035] The determination unit 63a determines whether the carrier gas CG is flowing in the bypass pipe BP. That is, the determination unit 63a determines whether it is a raw material gas generation operation or a bypass operation.

[0036] Specifically, the determination unit 63a determines whether the carrier gas CG flows in the bypass pipe BP based on the concentration or partial pressure of the raw material gas. In this embodiment, the determination unit 63a uses a ratio relative to a set concentration of the raw material gas or a preset fixed value as a threshold value to determine whether the carrier gas CG flows in the bypass pipe BP.

[0037] In this embodiment, the threshold value (first threshold value) for determining the situation of switching from "raw material gas generation operation (raw material gas generation state)" to "circling operation (circling state)" is set differently from the threshold value (second threshold value) for determining the situation of switching from "circling operation (circling state)" to "raw material gas generation operation (raw material gas generation state)".

[0038] Specifically, when determining the switch from "raw material gas generation operation" to "circumferential operation," the "ratio relative to the set concentration of the raw material gas," which serves as the first threshold value, can be conceived to be set to, for example, a concentration of 50% to 90% relative to the set concentration, and the "preset fixed value" can be conceived to be set to a concentration based on the "ratio relative to the set concentration of the raw material gas." On the other hand, when determining the switch from "circumferential operation" to "raw material gas generation operation," the "ratio relative to the set concentration of the raw material gas," which serves as the second threshold value, can be conceived to be set to, for example, a concentration of 10% to 50% relative to the set concentration, and the "preset fixed value" can be conceived to be set to a concentration based on the "ratio relative to the set concentration of the raw material gas." These threshold values ​​can be appropriately set by the user, and this setting is handled by the setting receiving unit 63c. Furthermore, the threshold value can be the same when determining the switch from "raw material gas generation operation" to "circling operation" and when determining the switch from "circling operation" to "raw material gas generation operation".

[0039] Furthermore, in determining the switch from "raw material gas generation operation" to "circumferential operation", the determination unit 63a compares the measured concentration of the raw material gas obtained by the concentration measuring unit 61 with a first threshold value. If the measured concentration is greater than the first threshold value, it is determined to be "raw material gas generation operation". If the measured concentration is less than the first threshold value, it is determined to be "circumferential operation". Moreover, in determining the switch from "circumferential operation" to "raw material gas generation operation", the determination unit 63a compares the measured concentration of the raw material gas obtained by the concentration measuring unit 61 with a second threshold value. If the measured concentration is less than the second threshold value, it is determined to be "circumferential operation". If the measured concentration is greater than or equal to the second threshold value, it is determined to be "raw material gas generation operation".

[0040] In addition, the determination unit 63a may also use "the ratio of the measured concentration to the previous normal control time (stable time)" or "the rate of change of the measured concentration per unit time" as the threshold value to determine whether the carrier gas CG is flowing in the bypass pipe BP.

[0041] The valve control unit 63b switches between concentration control and pressure control based on the determination result of the determination unit 63a. Specifically, during the raw material gas generation operation, the valve control unit 63b performs concentration control by feeding back the control valve 62 in a manner where the measured concentration of the raw material gas follows the set concentration (target concentration). Moreover, during the circumferential operation, the valve control unit 63b performs pressure control by feeding back the control valve 62 in a manner where the measured pressure (total pressure) of the pressure measuring unit 64 follows the set pressure (target concentration).

[0042] Here, the valve control unit 63b uses either a "preset fixed value" or the "pressure of the mixed gas during the raw material gas generation operation" as the set pressure for pressure control. Regarding the "pressure of the mixed gas during the raw material gas generation operation," for example, the pressure (total pressure) of the mixed gas during normal control (when the concentration is stable) of the raw material gas generation operation before switching to the bypass operation can be used. This mixed gas pressure is measured by the pressure measuring unit 64. When the concentration control unit in the valve control unit 63b calculates the set pressure corresponding to the set concentration during its internal processing, this set pressure can also be considered as the pressure of the mixed gas. Furthermore, the "preset fixed value" is set by the user and processed by the setting receiving unit 63c.

[0043] Furthermore, when the valve control unit 63b switches from pressure control to concentration control, it switches to raw material gas generation operation and then switches to concentration control after a predetermined time has elapsed. Specifically, when the valve control unit 63b switches from pressure control to concentration control based on the determination result of the determination unit 63a, it switches to concentration control after a predetermined time (e.g., 1 to 3 seconds) has elapsed since the determination unit 63a determined that the raw material gas generation operation has occurred.

[0044] Next, the changes in the concentration of the raw material gas when switching between concentration control and pressure control (this embodiment) and when performing continuous concentration control (previous example) are shown in Figure 3.

[0045] During the simulation, the set concentration of the raw material gas is set to 2.5 vol%. In this embodiment, regarding "supply stop (switching from raw material gas generation to orbiting action)," the first threshold (determination threshold) is set to 70% of the set concentration, and the pressure control command value is set to the pressure of the mixed gas 3 seconds prior to the time point when orbiting action is determined. Furthermore, the reason for setting it to 3 seconds prior is to use the pressure of the mixed gas during normal control (when the concentration is stable). Moreover, in this embodiment, regarding "supply start (switching from orbiting action to raw material gas generation action)," the second threshold (determination threshold) is set to 30% of the set concentration, and the switch to concentration control is performed 3 seconds after the time point when raw material gas generation action is determined. That is, the delay for switching to concentration control is set to 3 seconds.

[0046] As shown in Figure 3, in the previous example, after the self-circulating action switched to the raw material gas generation action, a significant overshoot in the concentration of the raw material gas occurred. On the other hand, it has been found that in this embodiment, the overshoot in the concentration of the raw material gas after the self-circulating action switched to the raw material gas generation action is suppressed. Furthermore, Figure 4 shows the pressure changes during the raw material gas generation action and the circulating action, but in this embodiment, it has been found that the pressure during both the raw material gas generation action and the circulating action is maintained at approximately a certain level.

[0047] <3. Effects of this embodiment> According to the raw material gasification system 100 configured in this embodiment, the concentration is controlled during the raw material gas generation operation and the pressure is controlled during the circumferential operation, so the overshoot of the raw material gas concentration that occurs immediately after the circumferential operation switches to the raw material gas generation operation can be suppressed.

[0048] Specifically, in this embodiment, the valve control unit 63b uses a preset fixed value or the pressure of the mixed gas during the feed gas generation operation for pressure control during the revolving operation. Therefore, the control valve 62 is not fully open during the revolving operation. As a result, even if the revolving operation switches to the feed gas generation operation, the overshoot of the feed gas concentration can be suppressed immediately after switching to the feed gas generation operation.

[0049] <4. Other embodiments> For example, in the embodiment, the concentration control module 6 is incorporated into the raw material gasification system, but the concentration control module 6 can also be a standalone structure.

[0050] Moreover, in the embodiment described, the determination unit 63a is used to automatically determine whether the raw material gas generation operation or the circumferential operation is performed. However, it can also be configured as follows: the control unit that controls the flow path switching valve V1 to the flow path switching valve V3 obtains operation information indicating whether it is a raw material gas generation operation or a circumferential operation.

[0051] In addition, various modifications or combinations of embodiments are possible as long as they do not depart from the spirit of the present invention. [Industrial Applicability]

[0052] According to the present invention, the overshoot of the concentration of the raw material gas generated when the self-circulating action is switched to the raw material gas generation action can be suppressed. [Simplified Explanation of the Diagram]

[0020] Figure 1 is a general schematic diagram of a feedstock gasification system according to an embodiment of the present invention. Figure 2 is a control block diagram of the concentration control module of the embodiment. Figure 3 shows the simulation results of the concentration change of the feedstock gas when switching between concentration control and pressure control in the embodiment (this embodiment) and when performing continuous concentration control (previous example). Figure 4 shows the simulation results of the pressure change of the mixed gas when switching between concentration control and pressure control in the embodiment (this embodiment) and when performing continuous concentration control (previous example).

Claims

1. A concentration control module for a raw material gasification system that performs a raw material gas generation action and a bypass action, wherein the raw material gas generation action introduces carrier gas into a storage tank containing raw material, the raw material is gasified by bubbling and the raw material gas is discharged through a discharge pipe equipped with a control valve, and the bypass action causes the carrier gas to flow in a bypass passage, bypass the storage tank and flow in the discharge pipe, and the concentration control module performs concentration control in the raw material gas generation action and pressure control in the bypass action, wherein the pressure control is based on the pressure measured in the pressure measuring unit provided in the discharge pipe following a set pressure, and feedback is given to the control valve.

2. The concentration control module as described in claim 1, comprising: The determination unit determines whether the carrier gas flows in the bypass passage; And a control unit, which switches between concentration control and pressure control based on the determination result of the determination unit.

3. The concentration control module as claimed in claim 2, wherein the determination unit determines whether the carrier gas flows in the bypass passage based on the concentration or partial pressure of the raw material gas.

4. The concentration control module as described in claim 2 or claim 3, wherein the determination unit uses a ratio relative to a set concentration of the raw material gas or a preset fixed value as a threshold value to determine whether the carrier gas flows in the bypass passage.

5. The concentration control module as described in claim 2 or claim 3, wherein the control unit uses a preset fixed value or the pressure of the mixture of the raw material gas and the carrier gas during the raw material gas generation operation as the set pressure in the pressure control.

6. The concentration control module as described in claim 2 or claim 3, wherein when the control unit switches from pressure control to concentration control, it switches to the raw material gas generation operation and, after a predetermined time, switches to concentration control.

7. A raw material gasification system, comprising: A storage tank containing liquid or solid raw materials; an inlet pipe for introducing carrier gas into the storage tank for bubbling; an outlet pipe for discharging a mixture of the carrier gas and the raw material gas formed by vaporization of the raw materials from the storage tank; and a concentration control module as described in any one of claims 1 to 6, disposed in the outlet pipe.

8. A concentration control method for a raw material gasification system that performs a raw material gas generation action and a bypass action, wherein the raw material gas generation action introduces carrier gas into a storage tank containing raw material, the raw material is gasified by bubbling and the raw material gas is discharged through a discharge pipe equipped with a control valve, and the bypass action causes the carrier gas to flow in a bypass passage, bypass the storage tank and flow in the discharge pipe, and the concentration control method performs concentration control in the raw material gas generation action and pressure control in the bypass action, wherein the pressure control is performed by feeding back to the control valve in such a way that the measured pressure of the pressure measuring unit provided in the discharge pipe follows the set pressure.

9. A concentration control program for a raw material gasification system that performs a raw material gas generation action and a bypass action, wherein the raw material gas generation action introduces carrier gas into a storage tank containing raw material, the raw material is gasified by bubbling and the raw material gas is discharged through a discharge pipe equipped with a control valve, and the bypass action causes the carrier gas to flow in a bypass passage, bypass the storage tank and flow through the discharge pipe, and the concentration control program performs concentration control by computer during the raw material gas generation action and pressure control by computer during the bypass action, wherein the pressure control is based on the pressure measured at a pressure measuring unit provided in the discharge pipe following a set pressure, and feedback is given to the control valve.

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