Vaporization tank

Abstract

A vaporization tank 10A includes: a housing 12 having a liquid inlet 10i and a gas outlet 10o; a first storage section 14A which is formed inside the housing and stores a liquid raw material L supplied from the liquid inlet; a second storage section 14B which is formed inside the housing and stores the liquid raw material L that has overflowed from the first storage section; a first liquid level gauge 24A which is provided suspended from a top plate 12a of the housing and detects the liquid level of the liquid raw material stored in the first storage section 14A; and a second liquid level gauge 24B which is provided suspended from the top plate of the housing and detects the liquid level of the liquid raw material stored in the second storage section 14B.

Description

Vaporization tank

[0001] The present invention relates to a vaporization tank, and more particularly to a vaporization tank used in a vaporization device capable of producing a relatively large flow rate of gas, which is configured to enable the state of the liquid material in the vaporization chamber to be checked.

[0002] In semiconductor manufacturing facilities, chemical plants, etc., various process gases such as raw material gases and etching gases are supplied to a process chamber. Known devices for controlling the flow rate of the supplied gases include mass flow controllers (thermal mass flow controllers) and pressure-type flow control devices.

[0003] In semiconductor manufacturing equipment for forming films by metalorganic chemical vapor deposition (MOCVD) or the like, a vaporization supply device is used to vaporize a liquid material and supply it to a process chamber as a source gas. Patent Document 1 discloses a vaporization supply device that heats a metalorganic source such as tetraethyl orthosilicate (TEOS) to a relatively high temperature, such as 200° C., to vaporize it, maintains the gas temperature, controls the flow rate, and supplies it to the process chamber.

[0004] Another proposed vaporizer for liquid materials is one that stores the liquid material in multiple trays arranged in multiple stages within a vaporization chamber and then vaporizes it. Patent Document 2 describes a vaporizer in which the liquid material is stored in multiple trays, and the liquid material in the trays is heated and vaporized by heaters provided on each tray or the housing. Patent Document 3 also discloses a vaporizer having multiple trays stacked vertically to support a source reagent.

[0005] In this way, by using multiple storage trays installed in the vaporization chamber, the liquid surface area of ​​the liquid material stored in the vaporization chamber can be increased, thereby increasing the amount of vaporization relative to the size. Furthermore, even when supplying a large flow rate of gas, the size of the vaporization device does not need to be increased, thereby saving space. In recent years, there has been a demand for even smaller spaces for devices placed around the process chamber, while at the same time, processes such as ALD (atomic layer deposition) require larger flow rates and larger exhaust volumes of supplied gas. For this reason, development of vaporizers with a larger gas supply rate relative to the size described above is underway.

[0006] International Publication No. 2019 / 021948 Japanese Patent Application Laid-Open No. 2023-87236 Japanese Patent No. 5266227 Japanese Patent Application Laid-Open No. 2021-148496 International Publication No. 2022 / 190711

[0007] In the vaporizer described above, it is preferable to be able to detect the amount of liquid material stored in the tank or tray at any time. During liquid supply, an appropriate amount of liquid must be supplied and stored in the tray. Furthermore, during vaporization supply, it is necessary to detect the amount of liquid reduced due to consumption of the material, and if there is a shortage, to replenish the liquid material and prevent a decrease in the gas supply amount or dry boiling.

[0008] Patent Document 4 describes a vaporizer configured to detect the liquid level (liquid volume) of a liquid source using a float sensor provided in a source container. Patent Document 5 also discloses a configuration in which a float sensor for measuring the liquid level is disposed in a tank in an ultrapure water vaporizer / supply device.

[0009] The float sensor allows the amount of liquid in the storage container to be constantly monitored, preventing excessive supply of liquid material to the container during liquid supply. Furthermore, when gas is supplied, a shortage of liquid in the container due to consumption can be detected, and by opening the valve to replenish the liquid, a certain amount of liquid or more can be stored in the vaporization chamber.

[0010] However, because float sensors are relatively large, it can be difficult to accurately detect the liquid level of a liquid pool stored in a relatively shallow tray. For this reason, conventional multi-tray vaporizers have the problem that it is not easy to detect the amount of liquid in each tray, and it is not possible to control operation according to the amount of liquid in the vaporization tank.

[0011] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a vaporization tank for use in a vaporization device that is relatively small yet can grasp the state of liquid material in the vaporization chamber and stably generate and supply a relatively large flow rate of raw material gas.

[0012] An evaporation tank according to an embodiment of the present invention comprises a housing having a liquid inlet and a gas outlet, a first storage section formed inside the housing for storing liquid raw material supplied from the liquid inlet, a second storage section formed inside the housing for storing liquid raw material that has overflowed from the first storage section, a first level gauge hanging down from the top plate of the housing for detecting the liquid level of the liquid raw material stored in the first storage section, and a second level gauge hanging down from the top plate of the housing for detecting the liquid level of the liquid raw material stored in the second storage section.

[0013] In one embodiment, the second level gauge has a plurality of liquid level detectors spaced apart in the height direction.

[0014] In one embodiment, the evaporation tank further has a bottom plate portion arranged horizontally at the middle height of the housing and a partition plate portion arranged vertically from the bottom plate portion, and the first storage portion is arranged so as to be surrounded by the bottom plate portion, the partition plate portion, and the side wall of the housing.

[0015] In one embodiment, the evaporation tank further has a tubular protrusion protruding upward from the bottom plate portion, and is configured so that liquid raw material overflowing from the first storage portion is supplied to the second storage portion via the tubular protrusion.

[0016] In one embodiment, a level gauge insertion recess into which the second level gauge is inserted is formed in the bottom surface of the second reservoir, and the bottom surface of the second reservoir is inclined toward the level gauge insertion recess.

[0017] In one embodiment, the vaporization tank has a plurality of fins that hang down from the top plate of the housing at least above the first storage portion.

[0018] In one embodiment, the housing further has a carrier gas inlet, the gas outlet is configured to communicate with the first storage section, and the carrier gas inlet is configured to communicate with the second storage section, and the carrier gas flowing in from the carrier gas inlet flows to the tubular protrusion via the second storage section, and from the tubular protrusion, flows to the gas outlet via a gas flow path formed by the multiple fins and the liquid level of the liquid raw material stored in the first storage section.

[0019] According to an embodiment of the present invention, a vaporization tank is provided that is suitable for use in a vaporization device that has a relatively large vaporization amount and is capable of appropriately detecting the state of the liquid material in the vaporization chamber.

[0020] FIG. 1 is a diagram schematically showing a gas supply system incorporating a liquid material vaporization device having a vaporization tank according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a vaporization tank according to an embodiment of the present invention. FIG. 3 is a plan view showing a first storage section of a vaporization tank according to an embodiment of the present invention. FIG. 4 is a plan view showing the internal bottom surface of a vaporization tank according to an embodiment of the present invention. FIG. 5 is a diagram schematically showing a vaporization tank according to another embodiment of the present invention. FIG. 6 is a diagram schematically showing a vaporization tank according to yet another embodiment of the present invention.

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

[0022] 1 shows a gas supply system 100 including a vaporizer 10 equipped with a vaporization tank 10A (see FIG. 2) according to an embodiment of the present invention. The gas supply system 100 includes a liquid material supply source 2, the vaporizer 10 that vaporizes a liquid material L from the liquid material supply source 2 to generate a source gas, a flow rate control device 15 that controls the flow rate of an exhaust gas Go containing the source gas generated by the vaporizer 10, a process chamber 4 connected downstream of the flow rate control device 15, and a vacuum pump 6 connected to the process chamber 4.

[0023] A liquid replenishment valve 7 is provided between the liquid material supply source 2 and the vaporizer 10. The liquid replenishment valve 7 is provided to control the supply of liquid material L from the liquid material supply source 2 to the vaporizer 10, and is used, for example, to pressure-feed a desired amount of liquid material L to the vaporizer 10 only while the liquid replenishment valve 7 is open. The liquid replenishment valve 7 may be fixed to a pipe connected to the lid of the vaporizer 10. As the liquid replenishment valve 7, for example, an air-operated valve (AOV) can be used.

[0024] A stop valve 8 is provided between the flow rate control device 15 and the process chamber 4 to reliably stop the supply of source gas to the process chamber 4. For example, an air-operated valve (AOV) can be used as the stop valve 8. Furthermore, a vacuum pump 6 can evacuate the process chamber 4 and the flow path. The flow rate control device 15 can control the flow rate of the gas supplied to the process chamber 4 while the downstream side is depressurized.

[0025] The flow rate of the raw material gas (or the exhaust gas Go containing the raw material gas) generated by the vaporization device 10 is controlled to a desired flow rate by a flow rate control device 15. As the flow rate control device 15, for example, a known pressure type flow rate control device or a thermal type flow rate control device can be used.

[0026] 2 and 3, a detailed configuration of vaporization tank 10A included in vaporization apparatus 10 of this embodiment will be described. Vaporization tank 10A includes a housing 12 for storing and vaporizing liquid material L from liquid material supply source 2 shown in Fig. 1. A top plate 12a of housing 12 is provided with a liquid inlet 10i for receiving liquid material L and a gas outlet 10o for discharging the source gas obtained by vaporizing liquid material L and the introduced carrier gas as exhaust gas Go.

[0027] The housing 12 is provided with a first reservoir 14A, to which the liquid material L is supplied directly from the liquid inlet 10i, and a second reservoir 14B, which stores the liquid material L that overflows from the first reservoir 14A. In the vaporization device 10, the first reservoir 14A and the second reservoir 14B are provided with individual or common heaters (not shown), which heat and vaporize the liquid material stored therein. The first reservoir 14A and the second reservoir 14B are provided with temperature sensors 20A and 20B, respectively, for measuring the temperature of the stored liquid material. The top plate 12a of the housing 12 is also provided with a pressure sensor connection 21 for measuring the internal gas pressure.

[0028] The heater for vaporizing the liquid material L may be, for example, a space heater or a jacket heater arranged to heat the vaporization chamber from outside the housing 12. By operating the heater using a temperature regulator based on the outputs of the temperature sensors 20A and 20B, the temperatures of the liquid material L and the vaporization chamber can be set to desired temperatures.

[0029] In this embodiment, first storage section 14A is a space above bottom plate 16, which is provided horizontally at an intermediate height of housing 12, and is formed by a space separated from second storage section 14B by a partition plate (partition wall) 18 extending vertically upward from bottom plate 16 to reach top plate 12a of housing 12. First storage section 14A is surrounded by bottom plate 16, partition plate 18, and the side wall of housing 12. Second storage section 14B is formed by a space outside first storage section 14A within housing 12, and includes a space below bottom plate 16 and a space outside the side of first storage section 14A separated by partition plate 18.

[0030] 3 , in this embodiment, the partition plate 18 is provided to form an L-shape when viewed from above. In this configuration, the first storage section 14A is defined as a space located above the bottom plate 16 and outside the L-shaped partition plate 18. The second storage section 14B is defined as a space that penetrates the bottom plate 16 inside the L-shaped partition plate 18 and extends below the bottom plate 16 directly below the first storage section 14A. Note that a communication section such as a plurality of through-holes may be provided in the upper part of the partition plate 18 to prevent a large difference in gas pressure between the first storage section 14A and the second storage section 14B.

[0031] In this embodiment, the liquid material L that overflows from the first storage section 14A is sent to the second storage section 14B below via a tubular protrusion 22 that extends so as to protrude upward from the bottom plate section 16 and has an upper opening located near the top plate 12a. The lower opening of the tubular protrusion 22 is located near the bottom plate section 16, and the liquid material L that passes inside the tubular protrusion 22 falls into the second storage section 14B directly below the first storage section 14A. As shown in FIG. 3 , the tubular protrusion 22 is disposed, for example, at a corner that faces a corner (a portion that forms part of the second storage section 14B) separated by the L-shaped partition plate section 18 when viewed from above.

[0032] Vaporization tank 10A is also provided with a first level gauge 24A for detecting the level of the liquid material stored in first storage section 14A and a second level gauge 24B for detecting the level of the liquid material stored in second storage section 14B. First level gauge 24A and second level gauge 24B are both provided to hang down from top plate 12a of housing 12.

[0033] 2, the first level gauge 24A has a single liquid level detector 24LL, while the second level gauge 24B has three liquid level detectors 24L, 24M, and 24H spaced apart in the vertical direction. The first level gauge 24A and the second level gauge 24B may be, for example, the same as the float sensor described in Patent Document 4.

[0034] In this configuration, liquid level detector 24LL of first level gauge 24A is used to confirm whether a minimum amount of liquid material is present in first reservoir 14A. In second level gauge 24B, lowermost liquid level detector 24L is used to confirm whether liquid material is present in second reservoir 14B, middle liquid level detector 24M is used to confirm whether liquid material is filled in the main reservoir of second reservoir 14B (here, the space below bottom plate 16), and uppermost liquid level detector 24H is used to confirm whether liquid material is filled in the sub-reservoir of second reservoir 14B (here, the space above bottom plate 16).

[0035] As described above, since the first reservoir 14A and the second reservoir 14B are each provided with a level gauge, the amount of liquid material being supplied to the interior of the vaporization tank 10A can be detected in detail. For example, if the liquid level detector 24LL cannot detect any liquid during the process, it is assumed that there is almost no liquid material in the interior of the vaporization tank 10A, and therefore it may be determined that an abnormality has occurred and the vaporization operation may be stopped. Also, if the liquid level detector 24L does not detect any liquid, it may be determined that there is not enough liquid material to continue the process, and the process may be terminated and the system may transition to a liquid replenishment mode.

[0036] Furthermore, when liquid level detection unit 24M detects liquid during the supply of liquid material to vaporization tank 10A, it may be determined that sufficient liquid has been supplied and the process may be started. Furthermore, when liquid level detection unit 24H detects liquid, it may be determined that an excessive amount of liquid has been supplied, creating the possibility of overflow, and an abnormal state.

[0037] As described above, liquid material L is first supplied from liquid inlet 10i to first storage portion 14A, and when liquid material L accumulates up to the height of the upper opening of tubular protrusion 22, liquid material L is thereafter supplied to second storage portion 14B via tubular protrusion 22. In this embodiment, the shape of the bottom of second storage portion 14B is designed as shown in FIG. 4 so that the liquid is guided to a region in second storage portion 14B where second liquid level gauge 24B is located.

[0038] As shown in Fig. 4, a recess is provided in the bottom surface of the second storage section 14B at the position of the corner where the second level gauge 24B is to be disposed, and a level gauge insertion recess 26 into which the second level gauge 24B is inserted is formed in this bottom surface. A step 28 is also provided in the bottom surface along a diagonal line connecting a first corner (the upper right corner in the figure) where the level gauge insertion recess 26 is provided and a second corner (the lower left corner in the figure) directly below the tubular protrusion 22 shown in Fig. 3, and the entire bottom surface is slightly sloped downward from the second corner toward the first corner (i.e., toward the level gauge insertion recess 26). In the illustrated example, the upper left region of the step 28 is higher, and the lower right region of the step 28 is lower.

[0039] By providing a height difference or slope on the bottom surface of second storage section 14B in this way, liquid material L that overflows from first storage section 14A and is supplied to second storage section 14B can be guided toward second level gauge 24B. This allows second level gauge 24B to detect the liquid level more accurately. Note that the location of the step and the direction of the slope are not limited to the example shown in the figure, and may be set appropriately depending on the positional relationship between tubular protrusion 22 and second level gauge 24B.

[0040] 3, the vaporization tank 10A of this embodiment is provided with a carrier gas inlet 30 for introducing a carrier gas Gc (or assist gas) such as an inert gas into the vaporization tank 10A. The carrier gas inlet 30 is provided so as to communicate with the second storage section 14B located inside the partition plate section 18. Meanwhile, the gas outlet 10o is provided so as to communicate with the first storage section 14A located outside the partition plate section 18. In the illustrated embodiment, the carrier gas inlet 30 is disposed above the first storage section 14A, but is not directly connected to the first storage section 14A. Instead, the carrier gas inlet 30 is directly connected to the second storage section 14B via a pipe or the like.

[0041] 2, first storage section 14A of vaporization tank 10A is provided with a plurality of fins 32 hanging down from top plate 12a of housing 12. As shown in Fig. 3, the plurality of fins 32 extend alternately from opposing side walls of housing 12 so as to form a serpentine flow path therebetween, with a gap formed between each fin and the front side wall.

[0042] In this configuration, the carrier gas flowing in from the carrier gas inlet 30 passes through the second reservoir 14B below the bottom plate 16, flows into the annular protrusion 22, passes through the annular protrusion 22, and flows into the first reservoir 14A. Then, in the first reservoir 14A, the carrier gas flows through a serpentine flow path formed by the multiple fins 32, and finally flows out from the gas outlet 10o.

[0043] In this way, by flowing the carrier gas Gc through a relatively long flow path through the second storage section 14B and the first storage section 14A, the mixing efficiency with the vaporized material gas is improved, and a mixed gas with little concentration unevenness can be obtained as the exhaust gas Go. Note that, by providing a plurality of fins 32 (typically made of metal) as described above, heat from the heater can be easily transferred to the stored liquid, thereby improving vaporization performance.

[0044] The above describes an evaporation tank according to an embodiment of the present invention, but the evaporation tank may have various forms as long as it has a first storage section and a second storage section and corresponding first and second liquid level gauges.

[0045] For example, as in the evaporation tank 10B shown in Figure 5, the first storage section 14A and the second storage section 14B may be arranged side by side, and the liquid material L that overflows from the first storage section 14A beyond the upper end surface of the partition plate section 18 may flow into the second storage section 14B and be stored there.

[0046] 6, a first reservoir 14A may be provided inside a tray 19 having a sidewall and a bottom, and a second reservoir 14B may be disposed below the first reservoir 14A. In this case, liquid material L that overflows the sidewall of the tray of first reservoir 14A falls downward and is stored in second reservoir 14B.

[0047] The vaporization tank according to the embodiment of the present invention is suitably used when generating various gases from liquid materials to be supplied to a process chamber in, for example, a semiconductor manufacturing device.

[0048] 2 Liquid material supply source 4 Process chamber 6 Vacuum pump 7 Liquid refill valve 8 Stop valve 10 Vaporizer 10A Vaporization tank 10i Liquid inlet 10o Gas outlet 12 Housing 12a Top plate 14A First storage section 14B Second storage section 15 Flow rate control device 16 Bottom plate section 18 Partition plate section 22 Tubular protrusion section 24A First liquid level gauge 24B Second liquid level gauge 26 Liquid level gauge insertion recess 28 Step 30 Carrier gas inlet 32 ​​Fin L Liquid material Go Exhaust gas (raw material gas and carrier gas) Gc Carrier gas

Claims

1. A vaporization tank comprising: a housing having a liquid inlet and a gas outlet; a first storage section formed inside the housing for storing liquid raw material supplied from the liquid inlet; a second storage section formed inside the housing for storing liquid raw material that overflows from the first storage section; a first level gauge suspended from the top plate of the housing for detecting the liquid level of the liquid raw material stored in the first storage section; and a second level gauge suspended from the top plate of the housing for detecting the liquid level of the liquid raw material stored in the second storage section.

2. The evaporation tank of claim 1, wherein the second level gauge has a plurality of liquid level detectors spaced apart in the vertical direction.

3. An evaporation tank as described in claim 2, having a bottom plate portion arranged horizontally at an intermediate height of the housing, and a partition plate portion arranged vertically from the bottom plate portion, wherein the first storage portion is surrounded by the bottom plate portion, the partition plate portion, and the side wall of the housing.

4. The vaporization tank according to claim 3, further comprising a tubular protrusion protruding upward from the bottom plate, wherein the liquid source overflowing from the first storage section is supplied to the second storage section via the tubular protrusion.

5. An evaporation tank as described in claim 4, wherein a level gauge insertion recess into which the second level gauge is inserted is formed on the bottom surface of the second storage section, and the bottom surface of the second storage section is inclined toward the level gauge insertion recess.

6. The vaporization tank according to claim 4, wherein a plurality of fins are provided hanging down from the top plate of the housing at least above the first storage section.

7. The vaporization tank of claim 6, wherein the housing further has a carrier gas inlet, the gas outlet is arranged to communicate with the first storage section, and the carrier gas inlet is arranged to communicate with the second storage section, and the carrier gas flowing in from the carrier gas inlet flows to the tubular protrusion via the second storage section, and from the tubular protrusion flows to the gas outlet via a gas flow path formed by the multiple fins and the liquid surface of the liquid raw material stored in the first storage section.

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