Raw material vaporization system, concentration control module used therein, concentration control method, and concentration control program

Abstract

The present invention, in order to suppress an overshoot of the concentration of a raw material gas that occurs when switching from a bypass operation to a raw material gas generating operation, provides a concentration control module for use in a raw material vaporization device that performs a raw material gas generating operation in which a carrier gas is introduced into a tank containing a raw material and the raw material is vaporized by bubbling to derive raw material gas, and a bypass operation in which the carrier gas is flown through a bypass path to bypass from the tank. The concentration control module performs concentration control in the raw material gas generating operation and pressure control in the bypass operation.

Description

[Technical Field]

[0001] The present invention relates to a raw material vaporization system that introduces a carrier gas into a liquid or solid raw material to vaporize it and supply the resulting raw material gas, as well as a concentration control module, concentration control method, and concentration control program used in the system. [Background technology]

[0002] As shown in Patent Document 1, this type of raw material vaporization system includes a tank for storing raw material, an inlet pipe for introducing a carrier gas into the tank to vaporize the raw material, and an outlet pipe for discharging a mixed gas of the carrier gas and the vaporized raw material from the tank.

[0003] The outlet pipe is provided with a concentration measuring unit for measuring the concentration of the source gas and a control valve. The control valve provided in the outlet pipe is controlled so that the measured concentration obtained by the concentration measuring unit becomes the set concentration, thereby controlling the concentration of the source gas. The control valve is feedback-controlled by the valve control unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-145887 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described raw material vaporization system, a purge line, which is a bypass pipe that bypasses the tank, is connected to the inlet pipe and outlet pipe, and an on-off valve is provided in the inlet pipe, outlet pipe, and bypass pipe to switch the flow path of the carrier gas between the tank and the bypass pipe.

[0006] In this raw material vaporization system, by controlling the on-off valve, it is possible to periodically switch between a raw material gas generation operation in which a carrier gas is introduced into a tank, the raw material is vaporized by bubbling, and the raw material gas is discharged, and a bypass operation in which the carrier gas is flowed through a bypass path and diverted from the tank.

[0007] However, when performing concentration control as described above, when switching from the raw material gas generation operation to the bypass operation, carrier gas flows through the outlet pipe, and the control valve is controlled by the valve control, resulting in a fully open state. After that, when switching from the bypass operation to the raw material gas generation operation, the control valve is in the fully open state, resulting in a large overshoot in the raw material gas concentration immediately after switching to the raw material gas generation operation.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and its main objective is to suppress the overshoot in the concentration of the raw material gas that occurs immediately after switching from the bypass operation to the raw material gas generation operation. [Means for solving the problem]

[0009] That is, the concentration control module of the present invention is a concentration control module used in a raw material vaporization system that performs a raw material gas generation operation in which a carrier gas is introduced into a tank containing a raw material, and the raw material is vaporized by bubbling to derive a raw material gas, and a detour operation in which the carrier gas is flowed into a bypass path to divert the carrier gas from the tank, and is characterized by performing concentration control in the raw material gas generation operation and pressure control in the detour operation.

[0010] Such a concentration control module performs concentration control during raw material gas generation operation and pressure control during bypass operation, thereby suppressing the overshoot in raw material gas concentration that occurs immediately after switching from bypass operation to raw material gas generation operation.

[0011] In order to enable the concentration control module to determine whether to perform the source gas generation operation or the bypass operation by itself without obtaining operational information from the source gas vaporization system (information indicating whether to perform the source gas generation operation or the bypass operation), the concentration control module preferably includes a determination unit that determines whether the carrier gas is flowing through the bypass path, and a control unit that switches between the concentration control and the pressure control based on the determination result of the determination unit. With this configuration, the concentration control module does not require communication equipment for obtaining operational information from the source gas vaporization system (information indicating whether to perform the source gas generation operation or the bypass operation).

[0012] As a specific embodiment of the determination unit, it is desirable that the determination unit determines whether or not the carrier gas is flowing through the bypass passage based on the concentration or partial pressure of the source gas.

[0013] As a specific embodiment of the judgment method in the judgment unit, it is desirable that the judgment unit judges whether the carrier gas is flowing through the bypass path using a ratio to the set concentration of the raw material gas or a predetermined fixed value as a threshold value.

[0014] As a specific embodiment of pressure control, it is desirable that the control unit uses a predetermined fixed value or the pressure of the mixed gas of the raw material gas and the carrier gas in the raw material gas generation operation as the set pressure in the pressure control.

[0015] If the pressure control is switched to the concentration control immediately after the bypass operation is switched to the source gas generation operation, an overshoot occurs in the source gas concentration. In order to suppress this overshoot, it is desirable that when switching from the pressure control to the concentration control, the control unit switches to the source gas generation operation after a predetermined time has elapsed.

[0016] The raw material vaporization system according to the present invention is characterized by comprising: a tank for storing a liquid or solid raw material; an inlet pipe for introducing a carrier gas into the tank to bubble the carrier gas; an outlet pipe for discharging a mixed gas of the carrier gas and a raw material gas obtained by vaporizing the raw material from the tank; and a concentration control module according to any one of claims 1 to 6 provided in the outlet pipe.

[0017] Furthermore, the concentration control method according to the present invention is a concentration control method for a raw material vaporization system that performs a raw material gas generation operation in which a carrier gas is introduced into a tank containing a raw material, and the raw material is vaporized by bubbling to derive a raw material gas, and a detour operation in which the carrier gas is caused to flow into a bypass path and detour away from the tank, characterized in that concentration control is performed in the raw material gas generation operation and pressure control is performed in the detour operation.

[0018] In addition, the concentration control program according to the present invention is a concentration control program for a raw material vaporization system that performs a raw material gas generation operation in which a carrier gas is introduced into a tank containing a raw material, and the raw material is vaporized by bubbling to derive a raw material gas, and a detour operation in which the carrier gas is caused to flow into a bypass path and is diverted from the tank, and is characterized in that the concentration control is performed by a computer in the raw material gas generation operation, and the pressure control is performed by the computer in the detour operation. [Effects of the Invention]

[0019] According to the present invention as described above, it is possible to suppress an overshoot in the concentration of the source gas that occurs immediately after switching from the bypass operation to the source gas generating operation. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is an overall schematic diagram of a raw material vaporization system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a control block diagram of a concentration control module according to the embodiment. [Figure 3]10 shows simulation results showing changes in the concentration of the source gas when the concentration control and pressure control of the embodiment are switched (this embodiment) and when the conventional concentration control is always performed (conventional example). [Figure 4] 10 is a simulation result showing a change in pressure of the mixed gas when the concentration control and pressure control of the embodiment are switched (this embodiment) and when the conventional concentration control is always performed (conventional example). DETAILED DESCRIPTION OF THE INVENTION

[0021] A raw material vaporization system according to one embodiment of the present invention will be described below with reference to the drawings.

[0022] <1. System configuration> The source material vaporization system 100 of this embodiment is used, for example, in a semiconductor manufacturing process, and supplies a source gas such as isopropyl alcohol (IPA) at a predetermined concentration to a drying processing chamber of a wafer cleaning apparatus. Alternatively, the source material vaporization system may supply a source gas at a predetermined concentration to a processing chamber of a semiconductor processing apparatus such as a CVD film formation apparatus or an MOCVD film formation apparatus.

[0023] This raw material vaporization system 100 introduces a carrier gas into a liquid or solid raw material, vaporizes it, and supplies the resulting raw material gas. Note that, although an example using a liquid raw material will be described below, the same applies to the case where a solid raw material is used.

[0024] Specifically, as shown in FIG. 1, the raw material vaporization system 100 includes a tank 2 that stores liquid raw material LM, an inlet pipe 3 that introduces a carrier gas CG into the tank 2 to bubble it, and an outlet pipe 4 that discharges a mixed gas MG of the carrier gas CG and the raw material gas obtained by vaporizing the raw material LM from the tank 2.

[0025] The tank 2 is an airtight container made of, for example, stainless steel that contains the liquid raw material LM, and is maintained at a constant temperature by an external heating mechanism such as a heater or a cooling mechanism.

[0026] A supply source (not shown) of a carrier gas CG such as nitrogen or hydrogen is connected to the upstream side of the introduction pipe 3, and the downstream side of the introduction pipe 3 is inserted into the tank 2. The downstream opening of the introduction pipe 3 is set at a position lower than the liquid level of the liquid raw material LM contained in the tank 2, and the raw material LM is bubbled by the carrier gas CG introduced into the tank 2 from the introduction pipe 3. In addition, the introduction pipe 3 is provided with a mass flow controller 5 for maintaining a constant flow rate of the carrier gas CG supplied into the tank 2.

[0027] An upstream opening of the outlet pipe 4 is connected to an upper space (gas phase) formed when the liquid raw material LM is contained in the tank 2. A processing chamber 200 of the semiconductor processing apparatus is connected to the downstream side of the outlet pipe 4. A concentration control module 6 is provided in the outlet pipe 4 to control the concentration of the raw material gas in the mixed gas MG.

[0028] Furthermore, a bypass pipe BP, which serves as a bypass path that bypasses (detouring) the tank 2, is connected to the inlet pipe 3 and the outlet pipe 4. The inlet pipe 3, the outlet pipe 4, and the bypass pipe BP are provided with flow path switching valves V1 to V3 that switch between a flow path through which the carrier gas CG passes through the tank 2 and a flow path through the bypass pipe BP. By controlling the opening and closing of these flow path switching valves V1 to V3, it is possible to switch between (1) a raw material gas generation operation (raw material gas generation state) in which the carrier gas CG is introduced into the tank 2 containing the raw material LM, and the raw material LM is vaporized by bubbling to discharge the raw material gas, and (2) a detouring operation (detouring state) in which the carrier gas CG is caused to flow through the bypass pipe BP and detouring from the tank 2.

[0029] <2. Density control module> Next, the density control module 6 of this embodiment will be described.

[0030] As shown in FIG. 1, the concentration control module 6 includes a concentration measuring unit 61 that measures the concentration of the raw material gas flowing through the outlet pipe 4, a control valve 62 provided in the outlet pipe 4 that discharges the raw material gas from the tank 2, and a control device 63 that feedback controls the control valve 62 based on the concentration measured by the concentration measuring unit 61.

[0031] In this embodiment, a pressure measuring unit 64 that measures the pressure (total pressure) inside the tank 2 is provided upstream of the control valve 62 in the outlet pipe 4. The pressure measuring unit 64 may be provided separately from the concentration control module 6.

[0032] The concentration measuring unit 61 continuously measures the concentration of the source gas in the mixed gas MG, and may use an NDIR sensor using a non-dispersive infrared absorption method (NDIR), an ultrasonic sensor utilizing the change in sound speed caused by a change in the concentration of the source gas, etc. The concentration measuring unit 61 may continuously measure the partial pressure of the source gas in the mixed gas MG, and measure the concentration of the source gas using the total pressure of the mixed gas MG obtained by the pressure measuring unit 64.

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

[0034] The control device 63 is a computer equipped with a CPU, memory, an A / D converter, an input / output interface, etc., and these parts work together based on a program stored in the memory to perform functions such as a judgment unit 63a, a valve control unit 63b, and a setting reception unit 63c, as shown in FIG. 2.

[0035] The determining unit 63a determines whether or not the carrier gas CG is flowing through the bypass pipe BP. That is, the determining unit 63a determines whether or not the operation is a raw material gas generating operation or a bypass operation.

[0036] Specifically, the determination unit 63a determines whether or not the carrier gas CG is flowing through the bypass pipe BP based on the concentration or partial pressure of the source gas. The determination unit 63a in this embodiment determines whether or not the carrier gas CG is flowing through the bypass pipe BP using a ratio to the set concentration of the source gas or a preset fixed value as a threshold.

[0037] In this embodiment, the threshold value (first threshold value) for determining whether to switch from "raw material gas generation operation (raw material gas generation state)" to "detour operation (detour state)" is set to be different from the threshold value (second threshold value) for determining whether to switch from "detour operation (detour state)" to "raw material gas generation operation (raw material gas generation state)".

[0038] Specifically, when determining whether to switch from the "raw material gas generation operation" to the "bypass operation," the first threshold value, "the ratio of the raw material gas to the set concentration," may be, for example, 50% to 90% of the set concentration, and the "predetermined fixed value" may be a concentration equivalent to the "ratio of the raw material gas to the set concentration." On the other hand, when determining whether to switch from the "bypass operation" to the "raw material gas generation operation," the second threshold value, "the ratio of the raw material gas to the set concentration," may be, for example, 10% to 50% of the set concentration, and the "predetermined fixed value" may be a concentration equivalent to the "ratio of the raw material gas to the set concentration." These threshold values ​​can be set appropriately by the user, and this setting is accepted by the setting accepting unit 63c. Note that the same threshold value may be used when determining whether to switch from the "raw material gas generation operation" to the "bypass operation" and when determining whether to switch from the "bypass operation" to the "raw material gas generation operation."

[0039] When determining whether to switch from the "raw material gas generation operation" to the "detour operation", the determination unit 63a compares the measured concentration of the raw material gas obtained by the concentration measurement unit 61 with a first threshold value, and determines the operation as a "raw material gas generation operation" if the measured concentration is greater than the first threshold value, and determines the operation as a "detour operation" if the measured concentration is equal to or less than the first threshold value. When determining whether to switch from the "detour operation" to the "raw material gas generation operation", the determination unit 63a compares the measured concentration of the raw material gas obtained by the concentration measurement unit 61 with a second threshold value, and determines the operation as a "detour operation" if the measured concentration is less than the second threshold value, and determines the operation as a "raw material gas generation operation" if the measured concentration is equal to or greater than the second threshold value.

[0040] Alternatively, the judgment unit 63a may use the "ratio to the measured concentration during the previous normal control (stable state)" or the "rate of change of the measured concentration per unit time" as a threshold value to judge whether carrier gas CG is flowing through 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, in the source gas generating operation, the valve control unit 63b performs concentration control by feeding back the control valve 62 so that the measured concentration of the source gas follows the set concentration (target concentration). In addition, in the bypass operation, the valve control unit 63b performs pressure control by feeding back the control valve 62 so that 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 a "predetermined fixed value" or the "pressure of the mixed gas in the raw material gas generating operation" as the set pressure in pressure control. Here, the "pressure of the mixed gas in the raw material gas generating operation" can be, for example, the pressure (total pressure) of the mixed gas during normal control (when the concentration is stable) in the raw material gas generating operation immediately before switching to the bypass operation. This mixed gas pressure is measured by the pressure measurement unit 64. If the concentration control unit in the valve control unit 63b calculates a set pressure that follows the set concentration in its internal processing, this set pressure may be considered to be the pressure of the mixed gas. The "predetermined fixed value" is set by the user and accepted by the setting acceptance unit 63c.

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

[0044] Next, FIG. 3 shows the change in concentration of the source gas when the concentration control and pressure control are switched (this embodiment) and when the conventional concentration control is always performed (conventional example).

[0045] In this simulation, the set concentration of the raw material gas was set to 2.5 vol%. In this example, for "supply stop (switching from raw material gas generation operation to detour operation)," the first threshold (determination threshold) was set to 70% of the set concentration, and the command value for pressure control was set to the mixed gas pressure 3 seconds before the detour operation was determined. The reason for setting it 3 seconds before is to use the mixed gas pressure during normal control (when the concentration is stable). In addition, in this example, for "supply start (switching from detour operation to raw material gas generation operation)," the second threshold (determination threshold) was set to 30% of the set concentration, and the control was switched to concentration control 3 seconds after the control was determined to be raw material gas generation operation. In other words, the delay for switching to concentration control was set to 3 seconds.

[0046] As shown in Fig. 3, in the conventional example, a large overshoot in the source gas concentration occurs immediately after switching from the bypass operation to the source gas generation operation. On the other hand, in this example, it can be seen that the overshoot in the source gas concentration immediately after switching from the bypass operation to the source gas generation operation is suppressed. Note that Fig. 4 shows the pressure changes during the source gas generation operation and the bypass operation, and it can be seen that in this example, the pressure is maintained at a nearly constant level during both the source gas generation operation and the bypass operation.

[0047] <3. Effects of this embodiment> According to the raw material vaporization system 100 of this embodiment configured as described above, concentration control is performed during raw material gas generation operation, and pressure control is performed during bypass operation, so that it is possible to suppress an overshoot in the raw material gas concentration that occurs immediately after switching from bypass operation to raw material gas generation operation.

[0048] Specifically, in this embodiment, the valve control unit 63b uses a preset fixed value or the mixed gas pressure in the raw material gas generating operation in pressure control during the detouring operation, so the control valve 62 does not enter a fully open state during the detouring operation. As a result, even when switching from the detouring operation to the raw material gas generating operation, it is possible to suppress an overshoot in the raw material gas concentration immediately after switching to the raw material gas generating operation.

[0049] <4. Other embodiments> For example, in the above embodiment, the concentration control module 6 is incorporated into the raw material vaporization system, but the concentration control module 6 may be configured as a standalone module.

[0050] In addition, in the above embodiment, the determination unit 63a was configured to automatically determine whether the raw material gas generation operation or the detour operation is being performed, but the configuration may also be such that operation information indicating whether the raw material gas generation operation or the detour operation is being performed is obtained from the control unit that controls the flow path switching valves V1 to V3.

[0051] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention. [Industrial Applicability]

[0052] According to the present invention, it is possible to suppress an overshoot in the concentration of the source gas that occurs when switching from the bypass operation to the source gas generating operation. [Explanation of symbols]

[0053] 100···Material Vaporization System 2 Tank 4...Outlet pipe 6. Concentration control module 61...Concentration measuring section 62 Valve 63b Valve control section

Claims

1. 1. A concentration control module used in a raw material vaporization system that performs a raw material gas generation operation of introducing a carrier gas into a tank containing a raw material, vaporizing the raw material by bubbling, and discharging the raw material gas through an outlet pipe provided with a control valve, and a detouring operation of flowing the carrier gas through a bypass path to detour the carrier gas from the tank into the outlet pipe, A concentration control is performed in the raw material gas generating operation, and a pressure control is performed in the bypassing operation, The pressure control is a concentration control module in which the control valve is fed back so that the measured pressure of a pressure measuring unit provided in the outlet pipe follows a set pressure.

2. a determination unit that determines whether the carrier gas is flowing through the bypass path; The concentration control module according to claim 1 , further comprising: a control unit that switches between the concentration control and the pressure control based on a determination result of the determination unit.

3. The concentration control module according to claim 2 , wherein the determining unit determines whether the carrier gas is flowing through the bypass path based on the concentration or partial pressure of the source gas.

4. 4. The concentration control module according to claim 2, wherein the determination unit determines whether the carrier gas is flowing through the bypass path using a ratio to a set concentration of the source gas or a preset fixed value as a threshold value.

5. A concentration control module described in any one of claims 2 to 4, wherein the control unit uses a predetermined fixed value or the pressure of a mixed gas of the raw material gas and the carrier gas in the raw material gas generation operation as the set pressure in the pressure control.

6. The concentration control module according to claim 2 , wherein the control unit, when switching from the pressure control to the concentration control, switches to the raw material gas generation operation and then switches to the concentration control after a predetermined time has elapsed.

7. a tank containing a liquid or solid raw material; an introduction pipe for introducing a carrier gas into the tank and bubbling it; an outlet pipe for delivering a mixed gas of the carrier gas and the vaporized raw material gas from the tank; A raw material vaporization system comprising: a concentration control module according to claim 1 provided in the outlet pipe.

8. A concentration control method for a raw material vaporization system, comprising: a raw material gas generating operation of introducing a carrier gas into a tank containing a raw material, vaporizing the raw material by bubbling, and discharging the raw material gas through an outlet pipe provided with a control valve; and a detouring operation of flowing the carrier gas through a bypass path to detour the carrier gas from the tank into the outlet pipe, a concentration control method in which concentration control is performed in the raw material gas generation operation, and pressure control is performed in the bypass operation, and the pressure control is performed by feeding back the control valve so that the measured pressure of a pressure measuring unit provided in the outlet pipe follows a set pressure.

9. 1. A concentration control program for a raw material vaporization system that performs a raw material gas generation operation of introducing a carrier gas into a tank containing a raw material, vaporizing the raw material by bubbling, and discharging the raw material gas through an outlet pipe provided with a control valve, and a detouring operation of flowing the carrier gas through a bypass path to detour the carrier gas from the tank into the outlet pipe, A concentration control program that causes a computer to perform concentration control during the raw material gas generation operation and causes the computer to perform pressure control during the bypass operation, and that feeds back the pressure control to the control valve so that the measured pressure of a pressure measuring unit provided in the outlet pipe follows a set pressure.

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