Vaporization apparatus and method for supplying gas

Abstract

To provide a vaporization apparatus that can detect a state of a liquid material that is stored in a tray.SOLUTION: A vaporization apparatus 10 includes: a housing 12 including a liquid inlet 10i and a gas outlet 10o; trays 14a, 14b, 14c installed in the housing to store a liquid material L dropping from the liquid inlet 10i; a heater for heating the liquid material stored in the trays 14a, 14b, 14c; and vibration sensors 16a, 16b, 16c installed in the trays 14a, 14b, 14c.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vaporizer, and more particularly to a vaporizer having a function for checking the state of a liquid material in a vaporization chamber. [Background technology]

[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 gas include mass flow controllers (thermal mass flow controllers) and pressure type flow control devices.

[0003] In semiconductor manufacturing equipment that forms films by metalorganic chemical vapor deposition (MOCVD) or the like, a vaporizer is used to vaporize a liquid material and then supply it to a process chamber as a raw material gas. Patent Document 1 discloses a vaporizer that heats and vaporizes a metalorganic raw material such as TEOS (Tetraethyl orthosilicate) to a relatively high temperature, such as 200°C, and supplies the gas to the process chamber while maintaining the gas temperature. The vaporizer is also used to supply HCDS (Si2Cl6) gas, which is a material for forming an insulating film.

[0004] As a vaporizer for liquid material, a device has been proposed in which the liquid material is stored in multiple trays arranged in multiple stages in a vaporization chamber and then vaporized. In the vaporizer described in Patent Document 2, the liquid material is stored in multiple trays, and the liquid material in each tray is vaporized by a heater provided on the tray or the housing.

[0005] In this way, by using multiple trays, the surface area of ​​the liquid material in the vaporization chamber can be increased, the amount of vaporization can be increased, and a larger flow rate of raw material gas can be supplied to the process chamber than in the past. In addition, even when supplying a large flow rate of gas, the size of the vaporization device does not need to be increased, so space can be saved and it can be appropriately arranged around the process chamber. In this case, there is also the advantage that the heat-insulating flow path required to prevent re-liquefaction of the vaporized gas can be made shorter.

[0006] In recent years, there has been a demand for further space saving in equipment placed around the process chamber, while at the same time, there is a demand for a large vaporization supply flow rate and a large exhaust volume in processes such as ALD (Atomic Layer Deposition). For this reason, progress is being made in developing vaporization equipment that uses multiple trays and is small, for example about 50 mm wide, but has a large vaporization supply volume. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 021948 [Patent Document 2] JP 2023-87236 A [Patent Document 3] International Publication No. 2022 / 190711 [Patent Document 4] International Publication No. 2021 / 200227 Summary of the Invention [Problem to be solved by the invention]

[0008] In the vaporizer as described above, it is preferable to be able to detect the amount of liquid material stored in the tank or tray at any time. When supplying liquid, it is necessary to supply and store an appropriate amount of liquid in the tray, and when supplying vapor, it is necessary to detect the amount of liquid that has decreased due to consumption of the material, and if there is a shortage, to replenish the liquid material, thereby preventing a decrease in the amount of gas supply and the occurrence of dry burning.

[0009] It is known to use a liquid level sensor as a means for detecting the amount of liquid in a tank in a vaporizer. Patent Document 3 discloses a configuration in which a float sensor for measuring the liquid level in a tank is disposed in an ultrapure water vaporizer. By using the float sensor, a shortage of liquid in the tank can be detected, and a certain amount or more of liquid can be stored in the vaporizer by opening a valve to refill the tank with liquid.

[0010] However, because the float sensor is relatively large, it is not suitable for detecting the liquid level of a shallow liquid pool stored in a tray with high accuracy. In particular, when placing the float sensor inside an evaporator, which is required to be compact, depending on the size of the float sensor, it may be difficult to install it.

[0011] In addition, if float sensors are placed on each tray, the liquid surface area will be reduced, and even if multiple trays are used to increase the liquid surface area, this will hinder an increase in the amount of vaporization. For this reason, the use of float sensors may not be appropriate, particularly in applications requiring a large flow rate of gas supply in a small device.

[0012] Furthermore, since float sensors are used by immersing them in liquid, there is a risk of corrosion depending on the liquid material used. Also, when a high-temperature liquid material is used, there is a risk that the float sensor will not be able to withstand the temperature change and will be damaged.

[0013] Therefore, there has been a demand for a vaporizer that is compact yet capable of detecting the state of liquid material stored in a tray without using a float sensor, while maintaining a large amount of vaporization.

[0014] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a vaporization device that is relatively small yet can appropriately generate a relatively large flow rate of raw material gas while keeping track of the state of the liquid material in the vaporization chamber. [Means for solving the problem]

[0015] An evaporation device according to an embodiment of the present invention comprises a housing having a liquid inlet and a gas outlet, a tray provided within the housing and capable of storing liquid material that drops from the liquid inlet, a heater for heating the liquid material stored in the tray, and a vibration sensor provided on the tray.

[0016] In one embodiment, the vibration sensor is a sensor capable of detecting at least one of a falling of the liquid material and a boiling of the liquid material.

[0017] In one embodiment, the vibration sensor is embedded in a bottom member of the tray.

[0018] In one embodiment, the vaporization device has a plurality of trays, the plurality of trays including an upper tray, a lower tray provided below the upper tray, and a bottom tray formed by the bottom of the housing, and is configured so that the liquid material falls from the liquid inlet onto the upper tray, liquid material overflowing from the upper tray falls onto the lower tray, and liquid material overflowing from the lower tray falls onto the bottom tray.

[0019] In one embodiment, the vibration sensor is provided on each of the plurality of trays.

[0020] In one embodiment, the upper tray is the topmost tray and is provided with a vibration sensor capable of detecting at least the boiling of the liquid material, and the bottom tray is the bottommost tray and is provided with a vibration sensor capable of detecting at least the falling of the liquid material.

[0021] A gas supply method according to an embodiment of the present invention is carried out using a vaporization device having a housing having a liquid inlet and a gas outlet, a plurality of trays provided within the housing and capable of storing liquid material dropped from the liquid inlet, the plurality of trays being arranged so that the liquid material supplied from the liquid inlet drops in sequence, a heater for heating the liquid material stored in the plurality of trays, and a plurality of vibration sensors each provided on the plurality of trays, and includes the steps of: generating a source gas by vaporizing the liquid material using the heater while the liquid material is stored in the plurality of trays, and sending out the generated source gas; The method includes the steps of: during the period in which the liquid material is being discharged, monitoring the output of a first vibration sensor provided on the tray among the multiple trays which is most likely to consume liquid material, to detect depletion of the liquid material in that tray; after detecting depletion of the liquid material in that tray, stopping the discharge of the raw material gas and replenishing liquid from the liquid inlet; during the period in which the liquid is being replenishing, monitoring the output of a second vibration sensor provided on the lowest tray among the multiple trays, to monitor the start of liquid material falling onto that tray; and stopping the replenishing of the liquid material based on detection by the second vibration sensor of the start of liquid material falling onto that tray. Effect of the Invention

[0022] According to an embodiment of the present invention, a vaporizer is provided that has a relatively large vaporization amount and is capable of detecting the state of the liquid material in the vaporization chamber. [Brief description of the drawings]

[0023] [Figure 1] 1 is a diagram illustrating a gas supply system incorporating a vaporizer according to an embodiment of the present invention; [Diagram 2] 1 is a diagram illustrating a vaporizer according to an embodiment of the present invention; [Diagram 3] 5A and 5B are diagrams showing output waveforms of a vibration sensor, in which (a) shows a liquid at rest and (b) shows a liquid boiling state. [Figure 4]FIG. 4 shows the results of frequency analysis (fast Fourier transform) of the output waveform shown in FIG. 3, where (a) shows the liquid at rest and (b) shows the liquid boiling. [Diagram 5] 4 is an exemplary flowchart illustrating a gas supply method using a vaporizer according to an embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram illustrating a vaporization device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment.

[0025] 1 shows a gas supply system 100 including a vaporizer 10 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 G, a flow rate control device 20 for controlling the flow rate of the source gas G generated by the vaporizer 10, a process chamber 4 connected downstream of the flow rate control device 20, and a vacuum pump 6 connected to the process chamber 4.

[0026] 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 the raw material supply piping of the vaporizer 10 (see FIG. 2). As the liquid replenishment valve 7, for example, an air-operated valve (AOV) can be used.

[0027] Furthermore, a stop valve 8 is provided between the flow rate control device 20 and the process chamber 4 to reliably stop the supply of the source gas G to the process chamber 4. The stop valve 8 may be incorporated in the flow rate control device 20. As the stop valve 8, for example, an air-operated valve (AOV) can be used.

[0028] The vacuum pump 6 can evacuate the process chamber 4 and the flow path. The flow rate control device 20 can control the flow rate of the gas supplied to the process chamber 4 while the downstream side is in a reduced pressure state. In this embodiment, a pressure type flow rate control device is used as the flow rate control device 20. The flow rate control device 20 includes a control valve 22, a throttle section 24 downstream of the control valve 22, and an upstream pressure sensor 26 that measures the gas pressure (upstream pressure P1) between the control valve 22 and the throttle section 24.

[0029] As the throttle unit 24, for example, an orifice plate or a critical flow nozzle can be used. In the flow control device 20, for example, the opening degree of the control valve 22 is feedback-controlled based on the output of the pressure sensor 28, thereby controlling the upstream pressure P1 and the gas flow rate downstream of the throttle unit 24. As the control valve 22, for example, a piezoelectric element-driven valve configured to be adjustable to an arbitrary opening degree by a piezoelectric actuator can be used.

[0030] More specifically, the flow control device 20 can control the flow rate by utilizing the principle that when the critical expansion condition: P1 / P2 ≧ about 2 (in the case of argon gas) is satisfied, the flow rate Q is determined by the upstream pressure P1, not by the downstream pressure P2, which is the pressure downstream of the throttling section 24. When the critical expansion condition is satisfied, the flow rate Q downstream of the throttling section 24 is given by Q=K1·P1 (K1 is a constant that depends on the type of fluid and the fluid temperature), and the flow rate Q is proportional to the upstream pressure P1. Furthermore, the flow control device 20 may be equipped with a downstream pressure sensor (not shown) that measures the downstream pressure P2. In this case, even if the critical expansion condition is not satisfied, the flow rate can be calculated, and Q=K2·P2m (P1-P2) n (Here, K2 is a constant that depends on the type of fluid and the fluid temperature, and m and n are exponents derived based on the actual flow rate.) The flow rate Q can be calculated from

[0031] The flow rate control device 20 calculates the flow rate Q=K1·P1 or Q=K2·P2 using a flow rate calculation formula under a critical expansion condition or a non-critical expansion condition. m (P1-P2) n The calculated flow rate is calculated from the flow rate, and the control valve 22 is feedback-controlled so that the flow rate of the gas passing through the throttle section 24 approaches the set flow rate (i.e., so that the difference between the calculated flow rate and the set flow rate approaches 0). This allows gas to flow at the desired set flow rate downstream of the throttle section 24.

[0032] However, the flow rate control device 20 is not limited to a pressure type flow rate control device, and may have other modes, for example, a thermal mass flow rate device, as long as it can appropriately control the flow rate of the raw material gas generated by the vaporizer 10. In addition, the illustrated flow rate control device 20 has a pressure sensor 28 that measures the pressure (supply pressure P0) upstream of the control valve 22, but this is not necessarily required. However, if the pressure sensor 28 is provided, an abnormal decrease in the amount of gas from the vaporizer 10 can be detected by monitoring the supply pressure P0. Therefore, if the supply pressure P0 falls below a threshold, it may be determined that an operational abnormality has occurred in the vaporizer 10, and a warning may be issued.

[0033] Furthermore, when performing an ALD process with a relatively large flow rate, a flow control device that does not have the throttle unit 24 and controls the opening and closing operation of the control valve 22 based on the output of the pressure sensor 28 may be used as the flow control device 20. Such a flow control device is disclosed in, for example, Patent Document 4. By performing pulse flow control based on the time change in the supply pressure P0 detected by the pressure sensor 28, the amount of gas supplied each time can be kept approximately constant, making it possible to appropriately perform an ALD process using a relatively large flow rate of gas.

[0034] Next, the vaporizer 10 of this embodiment will be described in detail with reference to Fig. 2. The vaporizer 10 has a housing 12 provided with a liquid inlet 10i for receiving a liquid material L and a gas outlet 10o for discharging a source gas G obtained by vaporizing the liquid material L.

[0035] The vaporizer 10 is configured to heat and vaporize the supplied liquid material L by a heater (not shown). In the vaporizer 10 shown in the figure, the liquid refill valve 7 shown in Fig. 1 is provided on a liquid supply pipe (liquid inflow path) forming a liquid inlet 10i at its open end, and the gas exhaust valve 9 is provided on a gas exhaust pipe (gas outlet path) forming a gas outlet 10o at its open end.

[0036] In the vaporizer 10, the heater that vaporizes the liquid material L can be, for example, a space heater or a jacket heater that is arranged to heat the inside (vaporization chamber) from the outside of the housing 12. The vaporizer 10 may be provided with a temperature sensor (not shown) for measuring the temperature of the liquid material L, and the temperature of the liquid material L and the vaporization chamber can be set to a desired temperature by operating the heater using a temperature regulator based on the output of the temperature sensor.

[0037] 2, the vaporizer 10 has a plurality of intermediate trays 14a, 14b (here, an upper tray 14a and a lower tray 14b) inside the housing 12. In this embodiment, the plurality of intermediate trays 14a, 14b are arranged to extend alternately from opposing inner sides of the housing 12 (left and right inner sides in FIG. 2) at different height positions. A gap is provided between the horizontal end of each of the intermediate trays 14a, 14b and the opposing inner side of the housing 12, and the liquid material L overflowing from each of the intermediate trays 14a, 14b can move downward through this gap.

[0038] Each of the intermediate trays 14a, 14b has a dish-like shape with side walls so that liquid can be stored inside, and the total surface area of ​​the liquid material stored in each of the intermediate trays 14a, 14b is increased in the housing 12. The bottom of the housing 12 also functions as a tray for storing the liquid material (sometimes referred to as bottom tray 14c here), and the total surface area of ​​the liquid material is increased. The upper tray 14a, the lower tray 14b, and the bottom tray 14c (and the entire housing 12) are formed from a material with excellent corrosion resistance, such as stainless steel (e.g., SUS316L).

[0039] In this embodiment, liquid material L is supplied to the vaporization device 10 by opening the liquid refill valve 7, causing the liquid material L to fall or drip from the liquid inlet 10i, which is the open end of a supply pipe connected to the top of the housing 12, onto the upper tray 14a.

[0040] In this embodiment, the liquid material L is first supplied to the upper tray 14a, and when the upper tray 14a is filled with liquid, the liquid material L falls over the side wall of the upper tray 14a onto the lower tray 14b. Furthermore, when the lower tray 14b is filled with liquid, the liquid material L falls over the side wall of the lower tray 14b onto the bottom tray 14c. In this manner, liquid can be supplied in sequence from the upper tray to the lower tray. The inner height (maximum liquid level height) of the side walls of the upper tray 14a and the lower tray 14b is set to, for example, about 5 mm.

[0041] The wall heights of the trays (liquid storage capacity of the trays) do not necessarily have to be the same, and some trays may have relatively low wall heights to be shallow trays. In this case, when liquid is consumed, liquid is preferentially depleted from the shallow trays. When trays of the same height are used, the liquid material is usually depleted first in the uppermost tray, which has a lower pressure, due to the pressure gradient in the vaporization chamber.

[0042] The upper tray 14a and the lower tray 14b may be provided in any manner as long as they have a shape capable of storing liquid. The upper tray 14a and the lower tray 14b do not necessarily need to be arranged to extend from alternate sides of the housing 12, and may be arranged to extend from the same side. In this case, the lower tray 14b may be larger in size so as to receive the liquid material overflowing from the upper tray 14a. Also, a protruding tube formed lower than the side wall may be provided on the bottom surface of the upper tray 14a and the lower tray 14b, and the liquid material exceeding the height of the protruding tube may be dropped down through the protruding tube. Also, trays of increasing size toward the lower level may be arranged along the central axis, or the trays may be arranged in a champagne tower shape.

[0043] 2 shows an embodiment in which two intermediate trays (trays disposed between the liquid inlet 10i and the bottom tray 14c), that is, upper tray 14a and lower tray 14b, other than bottom tray 14c, are provided, but it goes without saying that only one intermediate tray may be provided, or any number of intermediate trays, three or more, may be provided. Furthermore, as will be described later, the vaporizer may have only a bottom tray and not an intermediate tray.

[0044] Hereinafter, a mechanism for checking the state of the liquid material in the vaporization chamber in the vaporization device 10 of this embodiment will be described.

[0045] As shown in FIG. 2, the vaporizer 10 of this embodiment has vibration sensors 16a, 16b, and 16c embedded in the bottom members of the upper tray 14a, the lower tray 14b, and the bottom tray 14c, respectively. The vibration sensors 16a, 16b, and 16c are typically installed in a thin space formed from the outside as a gas system in the bottom member of each tray. For example, a vibration sensor, an acceleration sensor, an eddy current sensor, and a piezo film sensor can be used as the vibration sensors 16a, 16b, and 16c. A sensor having a rectangular and thin shape is preferably used as the vibration sensors 16a, 16b, and 16c. However, other types of vibration sensors may be used, such as a piezoelectric wire sensor or a piezoelectric wire, and in this case, the desired vibration is easily detected by arranging wire-shaped sensors in a rod shape. The vibration sensors 16a, 16b, and 16c may be vibration sensors of the same type or vibration sensors of different types.

[0046] The vibration sensors 16a, 16b, and 16c can detect vibrations generated in each tray. Therefore, when liquid is supplied to the trays, vibrations generated in the trays by the falling liquid material can be detected, and the start of supplying liquid to each tray can be detected. At this time, when the vibration sensor 16c provided on the bottom tray 14c at the lowest level detects the start of liquid supply, it can be determined that the upper trays 14a and 14b are almost full of liquid material, and it can also be determined that a sufficient amount of liquid material is stored in the vaporizer 10 at this point. In addition, it is usually considered that the magnitude (amplitude) of the vibration changes to a smaller one as the amount of liquid in the tray increases (i.e., the liquid level rises), so it is also possible to estimate the amount of liquid stored in each tray from the magnitude of the vibration.

[0047] Furthermore, when the liquid material stored in the tray is heated and vaporized, the liquid material boils and many bubbles are generated, particularly near the bottom, causing vibrations in the tray. For this reason, the vibration sensors 16a, 16b, and 16c detect the vibrations generated during vaporization, thereby making it possible to detect the boiling state. When the liquid material in the tray is consumed and depleted, boiling no longer occurs and the vibrations stop. Therefore, by detecting a reduction in the vibrations that have been continuously generated due to boiling, it is possible to know the depletion of the liquid material in the tray (the presence or absence of liquid material in the tray).

[0048] Figures 3(a) and (b) show the output waveforms of the vibration sensor in the static and boiling states of the experimental vaporizer, and Figures 4(a) and (b) show the frequency analysis (here, fast Fourier transform) of the output waveforms shown in Figures 3(a) and (b).

[0049] As can be seen from Fig. 3(a) and Fig. 4(a), in a stationary state where the stored liquid is not boiling, the output of the vibration sensor is very small, and no large peaks are observed at any frequency. On the other hand, as can be seen from Fig. 3(b) and Fig. 4(b), in a state where the stored liquid is boiling, the output of the vibration sensor increases significantly, and a peak is observed at the natural frequency. In this way, by detecting the vibration of the vaporizer using the vibration sensor, the boiling state inside can be detected. In addition, by performing a frequency analysis of the output waveform of the vibration sensor, it may be possible to estimate the amount of boiling liquid, etc., based on the frequency at which the peak appears.

[0050] In this way, in the vaporizer 10, the amount of liquid when the liquid is supplied and the boiling state when the liquid is vaporized can be known from the output of the vibration sensors 16a, 16b, and 16c. This may result in less information being obtained about the state of the liquid inside, compared to when the liquid level is directly measured at any time, such as when a float sensor is used.

[0051] However, the vibration sensors 16a, 16b, and 16c do not directly contact the liquid, so there is a low possibility of corrosion or damage, and they can be applied to shallow trays. Furthermore, important information for estimating the liquid state, particularly during liquid supply and vaporization, when detection of the liquid state, such as the liquid volume, is required, is obtained. Therefore, there is a great advantage in actual operation, particularly when a small-sized device supplies a large flow rate of gas. In addition, when the vibration sensors 16a, 16b, and 16c are used, maintenance is easy, and false detection due to a malfunction is easily recognized, so that normal conditions can be maintained and safety can be improved.

[0052] The vaporizer 10 may be configured to grasp the state of the liquid inside using the output of the vibration sensor and the output of the temperature sensor. The temperature sensor may be disposed, for example, in a fine hole provided in the bottom member of each tray. The vaporizer 10 may have a preheating tank in front of the vaporizer chamber, and a relatively high-temperature liquid material may be supplied. In this case, by referring to the output of the temperature sensor as well as the output of the vibration sensor, the start of liquid supply to each tray and the amount of liquid can be detected more accurately. Also, during boiling, by referring to the output of the temperature sensor as well as the output of the vibration sensor, it is possible to more accurately detect whether or not the state in which boiling actually occurs and liquid consumption is progressing due to evaporation continues.

[0053] When the vaporizer 10 configured in this manner is used to supply the source gas G, for example, when the liquid material in any of the multiple trays is depleted, the semiconductor manufacturing process may be temporarily terminated and the process may proceed to a step of replenishing the liquid material. At this time, the process being carried out may be completed using the remaining liquid in the vaporizer 10, and then the process may proceed to a liquid material replenishing mode. During vaporization and supply, it is considered that boiling occurs preferentially from the upper tray due to the occurrence of a pressure gradient, and consumption of the liquid material proceeds. Therefore, when boiling is no longer detected in the bottom tray (here, bottom tray 14c), it may be determined that the liquid material in the vaporization chamber has run out, and an abnormal stop may be performed.

[0054] When the gas supply is stopped, the pressure of the generated gas in the vaporization chamber is no longer reduced, and boiling does not occur. Therefore, when liquid is subsequently replenished, the possibility that the remaining liquid is in a boiling state is extremely low. Therefore, when liquid is replenished, the vibration sensor can detect only the vibration caused by the liquid falling, and the amount of liquid supplied can be properly known.

[0055] In order to efficiently increase the liquid surface area, it is preferable that the liquid level is lower than the height position of the lowest intermediate tray (here, the lower tray 14b) when refilling the liquid. For this reason, when refilling the liquid, the supply of the liquid material may be stopped at the point when vibration is detected in the bottom tray 14c. This prevents the liquid level from becoming higher than the position of the upper tray, and the liquid surface area can be increased to the maximum, thereby increasing the amount of vaporization. Furthermore, since the liquid surface area does not change even when liquid is consumed during vaporization, the gas generation ability in the vaporization chamber can be stabilized, and appropriate gas supply can be continuously performed.

[0056] In addition, the determination of the boiling state, the liquid dropping state, the boiling and liquid dropping state (for example, a state in which liquid dropping occurs due to unintentional seat leakage from the liquid refill valve during the supply of vaporized gas), and the stationary state can be made more accurately by performing frequency analysis of the output of the vibration sensor.

[0057] An example of a gas supply flow using the vaporizer 10 will be described below with reference to Fig. 5. First, as shown in step S1 of Fig. 5, a source gas is generated using a heater or the like in a state where a sufficient amount of liquid material is supplied to the vaporizer 10, and typically, the pressure in the vaporizer chamber (supply pressure P0) reaches the saturated vapor pressure, completing preparations for starting the process. At this time, the liquid replenishment valve 7 and the gas exhaust valve 9 are closed.

[0058] Next, as shown in step S2, the gas exhaust valve 9 is opened to start the process. At this time, the flow rate of the gas supplied to the process chamber 4 is controlled by the flow controller 20. As the process proceeds, the liquid material inside the vaporizer 10 is consumed and gradually decreases.

[0059] During this process, as shown in step S3, the first vibration sensor monitors whether the liquid has been depleted. Whether the liquid has been depleted can be determined by whether boiling no longer occurs on the tray and the output of the first vibration sensor drops rapidly to below a threshold value.

[0060] Here, in this embodiment, the first vibration sensor is a vibration sensor provided on a tray that is assumed to be depleted first during vaporization supply, and more specifically, is a vibration sensor 16a provided on the upper tray 14a. When the capacity of each tray is the same, the liquid material stored in the uppermost tray (or the tray closest to the gas outlet) is likely to boil and be consumed due to the influence of the pressure gradient. However, when the capacity of each tray is different, the tray with the smallest capacity may be the tray that is assumed to be depleted first. In this case, the first vibration sensor may not be the uppermost vibration sensor 16a, but may be, for example, the vibration sensor 16b provided on the lower tray 14b formed with a shallow bottom.

[0061] In step S3, if the first vibration sensor (here, vibration sensor 14a) does not detect depletion of liquid, it can be determined that there is still sufficient liquid material remaining in the vaporization device 10, as shown in step S4, and as shown in step S5, the process being carried out is continued, and if the process is carried out in a batch manner, the next process is started after the current process is completed.

[0062] On the other hand, if the first vibration sensor detects liquid depletion in step S3, it is determined that the current process is to be interrupted once it is completed, in order to replenish the liquid in the vaporizer 10 after completing the process currently being executed, as shown in step S6. At this time, since the first vibration sensor is the vibration sensor provided on the tray most likely to be depleted, it is considered that a reasonable amount of liquid material remains in the other trays when depletion in this tray is detected. Therefore, it is not necessary to immediately stop the current process, and the current process can be completed and liquid can be replenished afterwards without wasting the product.

[0063] Next, the current process is ended as shown in step S7, and the gas exhaust valve 9 is closed, and then the liquid replenishment valve 7 is opened to start the liquid replenishment step as shown in step S8.

[0064] At this time, as shown in step S9, it is monitored whether or not the second vibration sensor provided on the predetermined tray detects the start of the liquid falling. The falling of the liquid can be detected, for example, by whether or not the output of the second vibration sensor exceeds a threshold value for a predetermined period of time or more.

[0065] In this embodiment, the second vibration sensor is a vibration sensor provided on the lowermost tray, more specifically, vibration sensor 16c provided on bottom tray 14c. As shown in step S10, until the vibration sensor 16c detects the liquid dropping, it is determined that the amount of liquid supplied is still insufficient, and the liquid material continues to be replenished.

[0066] On the other hand, in step S9, when the second vibration sensor (vibration sensor 16c in this case) detects the start of the liquid falling, typically the upper trays (i.e., upper tray 14a and lower tray 14b) are filled with the liquid material, and the supply of the liquid material to the bottom tray (bottom tray 14c in this case) has also started.

[0067] Therefore, it can be determined that a sufficient but not excessive amount of liquid material has been supplied to the vaporizer 10, and as shown in step S11, the liquid refill valve 7 is closed and the refilling of the liquid is completed.

[0068] In step S9, after detecting the liquid falling onto the bottom tray, liquid may be supplied to the bottom tray for a predetermined short time before closing liquid replenishment valve 7. In addition, as the liquid is replenished in the bottom tray, the output of the second vibration sensor may gradually decrease with the rise in the liquid level. For this reason, liquid replenishment valve 7 may be closed when the output of the second vibration sensor falls below a threshold value. Furthermore, since the liquid remaining in the flow path is supplied to vaporizer 10 even after liquid replenishment valve 7 is closed, if the amount is appropriate, liquid replenishment valve 7 may be closed simultaneously with detection.

[0069] In this way, after the vaporizer 10 is replenished with an appropriate amount of liquid material, the process returns to step S1 and can be carried out according to the same flow thereafter. In this method, even if liquid needs to be replenished thereafter, the current process can be completed with a margin of liquid, and since the liquid can be replenished with an appropriate amount each time, stable process execution can be continued efficiently.

[0070] Fig. 6 shows another embodiment of the vaporizer 10B. Note that the same components as those in the vaporizer 10 shown in Fig. 1 are given the same reference numerals and the description thereof may be omitted.

[0071] Vaporizer 10B has only bottom tray 14c and no intermediate tray, and is configured so that liquid material L supplied via liquid replenishment valve 7 drops directly from liquid inlet 10i at the top onto the bottom surface of housing 12 and is stored therein. The stored liquid material L is heated and vaporized by a heater (not shown) in the same manner as vaporizer 10 shown in Fig. 1. The generated raw material gas G is sent from gas outlet 10o at the top via gas exhaust valve 9 to a flow rate control device or the like.

[0072] In vaporizer 10B, an upper surface vibration sensor 18a is provided on the upper surface of housing 12, and a lower surface vibration sensor 18b is provided on the lower surface of housing 12. Acceleration sensors that detect vibrations in the z-axis direction can be used as upper surface vibration sensor 18a and lower surface vibration sensor 18b.

[0073] When liquid is supplied, vibrations occur due to the liquid falling. When the amount of liquid is small, the output of the lower surface vibration sensor 18b is considered to be large, and when the amount of liquid is large, the output of the lower surface vibration sensor 18b is considered to be small. On the other hand, the output of the upper surface vibration sensor 18a is considered to be small when the amount of liquid is small, and large when the amount of liquid is large. This is because the output of the upper surface vibration sensor 18a detects vibrations that occur when the liquid collides with the liquid surface as it falls, so when the amount of liquid is large, the vibration detected by the upper surface vibration sensor 18a, which is closer to the liquid surface, becomes larger, and when the amount of liquid is small, the vibration detected by the lower surface vibration sensor 18b becomes larger. In this way, the amount of liquid when liquid is supplied can be estimated based on the outputs of the upper surface vibration sensor 18a and the lower surface vibration sensor 18b.

[0074] Furthermore, during vaporization and supply, boiling occurs in the stored liquid, and since the lower surface vibration sensor 18b mainly detects vibrations caused by the generation of bubbles that occur particularly near the bottom surface (heat transfer surface) during boiling, it is considered that the output is large regardless of the amount of liquid. On the other hand, the output of the upper surface vibration sensor 18a is considered to be small when the amount of liquid is small and large when the amount of liquid is large. This is because the upper surface vibration sensor 18a is likely to detect vibrations caused by the bubble sounds that occur at the liquid surface during boiling, and therefore is considered to detect larger vibrations as the liquid surface is closer. In this way, the boiling state and the remaining liquid amount (or liquid consumption amount) during vaporization and supply can be estimated based on the outputs of the upper surface vibration sensor 18a and the lower surface vibration sensor 18b. [Industrial Applicability]

[0075] The vaporizer according to the embodiment of the present invention is suitably used, for example, when generating various gases from liquid materials to be supplied to a process chamber in a semiconductor manufacturing device. [Explanation of symbols]

[0076] 2 Liquid material source 4. Process chamber 6. Vacuum Pump 7 Fluid refill valve 8 Stop valve 9 Gas exhaust valve 10 Vaporizer 10i liquid inlet 10o Gas outlet 12. Cabinet 14a Top Tray 14b Lower Tray 14c Bottom Tray 16a, 16b, 16c Vibration sensors 18a Top vibration sensor 18b Bottom vibration sensor 20 Flow Control Device L Liquid material G Raw material gas

Claims

1. A housing having a liquid inlet and a gas outlet, A tray is provided inside the housing and is capable of storing the liquid material that falls from the liquid inlet, A heater for heating the liquid material stored in the tray, A vibration sensor provided on the tray and A vaporizer equipped with the following features.

2. The vaporizer according to claim 1, wherein the vibration sensor is a sensor capable of detecting at least one of the falling of the liquid material and the boiling of the liquid material.

3. The vaporization apparatus according to claim 1, wherein the vibration sensor is embedded in the bottom member of the tray.

4. The device has a plurality of trays, each of which includes an upper tray, a lower tray located below the upper tray, and a bottom tray formed by the bottom of the housing. The vaporization apparatus according to claim 1, configured such that the liquid material falls from the liquid inlet into the upper tray, the liquid material overflowing from the upper tray falls into the lower tray, and the liquid material overflowing from the lower tray falls into the bottom tray.

5. The vaporization apparatus according to claim 4, wherein each of the plurality of trays is provided with the vibration sensor.

6. The vaporizer according to claim 4 or 5, wherein the upper tray is the topmost tray and is equipped with at least a vibration sensor capable of detecting the boiling of the liquid material, and the bottom tray is the bottommost tray and is equipped with at least a vibration sensor capable of detecting the dropping of the liquid material.

7. A housing having a liquid inlet and a gas outlet, A plurality of trays provided inside the housing, capable of storing liquid material that falls from the liquid inlet, wherein the plurality of trays are arranged so that the liquid material supplied from the liquid inlet falls sequentially, A heater for heating the liquid material stored in the aforementioned trays, Each of the above multiple trays is provided with multiple vibration sensors and A gas supply method using a vaporizer having, The process involves generating a raw material gas by vaporizing the liquid material using the heater while the liquid material is stored in the aforementioned multiple trays, and then discharging the generated raw material gas. During the period in which the raw material gas is being supplied, the output of a first vibration sensor installed on the tray among the plurality of trays that is most likely to consume liquid material is monitored to detect the depletion of liquid material in that tray. After detecting the depletion of the liquid material in the tray, the process involves stopping the supply of the raw material gas and replenishing the liquid from the liquid inlet. During the period in which the liquid is being replenished, the output of a second vibration sensor installed on the lowest tray of the plurality of trays is monitored to monitor the start of the liquid material falling into that tray. Based on the detection by the second vibration sensor of the start of the liquid material falling into the tray, the step of stopping the replenishment of the liquid material and A method of supplying gas, including a gas supply method.

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