JP4171664B2 - Liquid volume measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid amount measuring apparatus for measuring a liquid amount in a container in which a liquid material, particularly a liquid material used in a semiconductor manufacturing process or the like is stored.
[0002]
[Prior art]
When manufacturing microelectronic devices such as semiconductor integrated devices, liquid crystal panels, and optical elements, (CH ₃ C ₅ H ₄ ) ₃ Er, Er (C ₁₁ H ₁₉ O ₂ ) ₃ , ErCl ₃ / C ₂ H ₅ Materials such as OH, POCl ₃ , TiCl ₄ , Si (OC ₂ H ₅ ) ₄ (TEOS), Ta (OC ₂ H ₅ ) ₅ (PET) may be used. When these materials are used in a semiconductor manufacturing process or the like, in recent years, there is a tendency to store in a container in a liquid state and to supply a supply destination in a liquid state. In addition, these materials are relatively expensive special materials that are flammable and toxic, and they must be handled with care. Therefore, it is necessary to accurately measure and manage the amount of liquid in the container. is there.
[0003]
Conventionally, as means for measuring the amount of liquid in a container, means for measuring the amount of liquid by arranging a float type sensor in the container (for example, see Patent Document 1 below), means for using a weight meter comprising a load cell, etc. It has been known. There is also a means for measuring the amount of liquid from the outside with an optical fiber sensor by providing a glass window on the side wall of the container. Furthermore, for a container of a type in which a pressurized gas such as nitrogen gas is introduced to supply the liquid material in the container to the supply destination, the introduction amount of the pressurized gas should correspond to the supply amount of the liquid material to the supply destination. Therefore, means for obtaining the remaining amount in the container by managing the amount of pumped gas introduced by an integrating flow meter is also considered.
[0004]
[Patent Document 1]
Japanese Patent Application No. 2001-347824
[Problems to be solved by the invention]
However, the conventional liquid amount measuring means as described above have the following problems.
[0006]
First, the means using the float sensor may contaminate the liquid material in the container.
[0007]
Moreover, when using a weight scale, since various piping is connected to the container, there exists a problem that accuracy is low.
[0008]
In the means for measuring from the outside by providing a glass window, the durability of the sealing material between the side wall of the container and the glass window may be a problem. In particular, when the material stored in the container is a high melting point material such as (CH ₃ C ₅ H ₄ ) ₃ Er or Er (C ₁₁ H ₁₉ O ₂ ) ₃ , the container is used to keep the material in a liquid state. Since it is heated by the surrounding heater, the sealing material may be deteriorated by heat shrinkage, and the material may leak.
[0009]
Further, in the means for obtaining the liquid amount from the introduction amount of the pressurized gas, if the initial value of the integrating flow meter becomes unknown for some reason, the liquid amount is completely unknown.
[0010]
An object of the present invention is to solve the above conventional problems and to provide an apparatus capable of accurately measuring the amount of liquid in a container.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is a container for storing a liquid material, wherein the liquid material in the container is capable of pumping the liquid material to the supply destination by feeding the pumped gas. In the apparatus for measuring the amount of liquid, pressure detection means for detecting the gas pressure in the container, gas discharge amount detection means for detecting the discharge amount of gas discharged from the container, pressure detection means and gas discharge amount Computational processing means for obtaining the liquid amount of the liquid material in the container based on a detection value from the detection means is provided. An integrating flow meter is effective as the gas discharge amount detection means.
[0012]
In such a configuration, the liquid amount of the liquid material can be obtained from data on only the gas pressure in the container and the gas discharge amount. For example, when gas for atmospheric pressure is discharged from the container, the amount of gas discharged matches the volume of the space in the container (excluding the liquid material), so the liquid pressure is calculated from the gas pressure and gas discharge in the container. A quantity is required.
[0013]
Specifically, the arithmetic processing unit can determine the liquid amount based on the following equation.
W = [V ₀ −Q / {(P ₁ −P ₂ ) × 10}] × ρ
(W: Volume of liquid material in container (kg)
V ₀ : the total volume of the container (L),
Q: Gas emission amount (L) from the measurement start time point to the measurement end time point detected by the gas discharge amount detection means,
P ₁ : gas pressure (MPa) in the container at the measurement start time detected by the pressure detection means,
P ₂ : gas pressure (MPa) in the container at the end of measurement detected by the pressure detection means,
ρ: Liquid density of liquid material (kg / L)
[0014]
In addition, a liquid amount measuring apparatus according to another aspect of the present invention includes a first pressure detection unit that detects a gas pressure in a container, a buffer tank that can accumulate gas discharged from the container, and a buffer tank. Second pressure detecting means for detecting the gas pressure in the container, and arithmetic processing means for calculating the liquid amount of the liquid material in the container based on the detection values from the first pressure detecting means and the second pressure detecting means Are provided.
[0015]
In this case, since the volume in the buffer tank (that is, the amount of gas released) is known in advance, the liquid amount is obtained from the amount of change in the gas pressure in the buffer tank and the container.
[0016]
Specifically, the arithmetic processing means can calculate the liquid amount based on the following equation. W = [V ₀ −V _B × {(P _B2 −P _B1 ) × 10} / {(P _A1 −P _A2 ) × 10}] × ρ
(W: Volume of liquid material in container (kg)
V ₀ : the total volume of the container (L),
V _B : Buffer tank volume (L)
P _A1 : gas pressure (MPa) in the container at the measurement start time detected by the first pressure detection means,
P _A2 : gas pressure (MPa) in the container at the end of measurement detected by the first pressure detection means,
P _B1 : gas pressure (MPa) in the buffer tank at the measurement start time detected by the second pressure detection means,
P _B2 : gas pressure (MPa) in the buffer tank at the end of measurement detected by the second pressure detection means,
ρ: Liquid density of liquid material (kg / L)
[0017]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Moreover, the same code | symbol shall be attached | subjected to the same or an equivalent part in all the figures.
[0018]
FIG. 1 is an explanatory view schematically showing a liquid amount measuring apparatus 10 according to the first embodiment of the present invention. Prior to the description of the liquid amount measuring device 10, the liquid supply device 12 in which the liquid amount measuring device 10 is used will be described first.
[0019]
The liquid supply device 12 is for supplying a liquid material 14 used in a process for manufacturing a semiconductor device, a liquid crystal panel, or the like from a container 16 to a predetermined supply destination by a pressure gas such as nitrogen gas. In the first embodiment, (CH ₃ C ₅ H ₄ ) ₃ Er is stored in the container 16 as the liquid material 14 and is sent to the supply destination.
[0020]
The container 16 is a cylindrical sealed container made of a material having excellent corrosion resistance. Since the liquid material 14 to be stored in a liquid state in the container 16, that is, (CH ₃ C ₅ H ₄ ) ₃ Er, has a melting point of 133 ° C. and becomes a solid at room temperature, the container 16 has (CH ₃ C ₅ H ₄ ) Surrounded by a heater 18 for keeping ₃ Er in a liquid state.
[0021]
In the illustrated embodiment, four pipes 22, 24, 26, and 28 are provided through the top plate portion 20 of the container 16. The pipe 22 is a liquid material supply pipe extending to the supply destination, and the end in the container 16 is disposed in the vicinity of the bottom of the container. The pipe 24 is a pumping gas introduction pipe having one end connected to a pumping gas supply source (not shown), and the other end is terminated near the top plate portion 20 in the container 16. A pressurized gas such as nitrogen gas is introduced into the container 16 through the pipe 24, and the pressure in the space 30 (the area above the liquid surface of the liquid material) 30 in the upper part of the container 16 is positive, preferably an atmospheric pressure of 0. If the pressure (0.3 MPa) exceeds twice 1 MPa, (CH ₃ C ₅ H ₄ ) ₃ Er in the container 16 is pumped to the supply destination via the pipe 22.
[0022]
The pipe 26 is for replenishing the container 16 with a liquid material, and is connected to an exchangeable container (not shown) called a mother tank. That is, when the amount of liquid in the container 16 becomes equal to or less than a predetermined amount, the mother tank is connected to the pipe 26 and the liquid material 14 is appropriately replenished from the mother tank into the container 16.
[0023]
The pipe 28 is a vent line for releasing the pressure of the upper space 30 in the container 18 and constitutes a part of the liquid amount measuring apparatus 10 according to the present embodiment. One end of the pipe 28 is disposed in the vicinity of the top plate portion 20 in the container 18, whereby the inside of the pipe 28 is communicated with the upper space 30 in the container 18.
[0024]
The liquid amount measuring apparatus 10 further includes a pressure sensor (pressure detecting means) 32 connected to the pipe 28 and an integrating flow meter (gas discharge amount detecting means) 34 interposed in the pipe 28. . The pressure sensor 32 detects the gas pressure in the container 18 (pressure in the space 30). Further, the integrating flow meter 34 is configured such that one of the on-off valves 36 and 38 is closed from the time when the on-off valves 36 and 38 provided in the pipe 28 are opened. The total amount of gas discharged from the container 18 until it is discharged). The pressure sensor 32 and the integrating flow meter 34 are connected to a control device (arithmetic processing means) 40 composed of a microcomputer. The control device 40 performs the following based on signals from the pressure sensor 32 and the integrating flow meter 34. The amount of liquid in the container 18 can be calculated by the method shown in FIG.
[0025]
In the first embodiment, the liquid material 14 is (CH ₃ C ₅ H ₄ ) ₃ Er and is heated and liquefied by the heater 18. Therefore, when measuring the liquid amount, the liquid material 14 may be affected by temperature. Therefore, it is preferable that the pipe 28 is composed of a heat insulating pipe. In addition, on-off valves 42, 44, 46 are also provided in the pipes 22, 24, 26, respectively. The on-off valves 42, 44, 46 and the on-off valves 36, 38 in the pipe 28 are controlled by the control device 40. Open / close controlled.
[0026]
Next, a method for measuring the liquid amount of the liquid material 14 in the container 16 using the liquid amount measuring apparatus 10 having the above configuration will be described.
[0027]
First, when the measurement start switch 48 is turned on, the control device 40 issues a control signal to temporarily close all the on-off valves 36, 38, 42, 44, 46. Further, the integrating flow meter 34 is reset and the integrated value is set to “0”.
[0028]
Next, the control device 40 sends a control signal to the on-off valve 36, opens it, and detects the pressure in the space 30 in the container 16 by a signal from the pressure sensor 32. Now, it is assumed that the detected pressure value is the aforementioned 0.3 MPa.
[0029]
If the pressure in the container 16 is detected, the control device 40 opens the on-off valve 38. Accordingly, since the space 30 in the container 16 is at a positive pressure, the gas (mixed gas of nitrogen and (CH ₃ C ₅ H ₄ ) ₃ Er) is discharged through the pipe 28. The exhaust gas is appropriately processed in a gas processing device (not shown). The control device 40 monitors the pressure detection value from the pressure sensor 32, and closes the on-off valves 36 and 38 when the pressure reduction amount becomes 0.1 MPa, that is, when the pressure detection value becomes 0.2 MPa. Then, the integrated value of the integrating flow meter 34 is read.
[0030]
When the gas pressure in the container 16 is reduced by 0.1 MPa, a mixed gas such as nitrogen corresponding to the atmospheric pressure is released to the outside from the space 30 in the container 16. The amount of gas discharged for atmospheric pressure corresponds to the volume of the space 30 at atmospheric pressure. Therefore, if the integrated value of the integrating flow meter 34 is 1 L (liter), the volume of the space 30 in the container 16 is the integrated value itself, that is, 1 L. Since the volume of the entire container 16 is known in advance, if the value is, for example, 3L, the liquid amount of the liquid material 14 is obtained as 2L. Of course, since the liquid density of the liquid material 14 is known, the liquid amount of the liquid material 14 can be expressed as a weight. The amount of liquid is obtained by calculating the above in the control device 40.
[0031]
The control device 40 may display the obtained liquid amount on an appropriate display device 50, or may turn on an alarm lamp 52 when the liquid amount falls below a predetermined value. This makes it possible to accurately know the replenishment timing of the liquid material 16.
[0032]
The above calculation method is represented by a general formula. The gas pressure in the container 16 at the start of measurement is P ₁ (MPa), the gas pressure at the end of measurement is P ₂ (MPa), and the integrated value of the integrating flow meter 34 from the start to the end of measurement is Q (L ), The total volume in the container 16 is V ₀ (L), the volume of the space 30 in the container 16 is V ₁ (L), and the liquid amount (volume) of the liquid material 14 in the container 16 is V ₂ (L). Then, the volume V ₁ of the space 30 in the container 16 is as follows.
V ₁ = Q / {(P ₁ −P ₂ ) × 10} (1)
[0033]
Therefore, the volume V ₁ of the liquid material 14 in the container 16 is V ₂ = V ₀ −V ₁ (2)
When the liquid density of the liquid material 14 is ρ (kg / L), the liquid amount of the liquid material 14 is expressed by weight W (kg).
W = V ₂ × ρ (3)
It becomes. From the above formulas (1) to (3),
W = [V ₀ −Q / {(P ₁ −P ₂ ) × 10}] × ρ (4)
Is obtained.
[0034]
The above example is a case where P ₁ -P _{2 is set} to 0.1 MPa. However, when the general formula (4) is used, the values of V ₀ , P ₂ , and ρ may be stored in the control device 40 in advance. detects the P ₁ at the time of measurement start, only the detection values of the pressure sensor 32 detects the Q of when it becomes a predetermined P _2, can be determined remaining amount W of the liquid material 14.
[0035]
In addition, since the integrated flow meter 34 is used in the above embodiment, the output value thereof matches the gas discharge amount. However, the integrated value is calculated in the control device 40 using a normal flow meter. Also good.
[0036]
In the above embodiment, (CH ₃ C ₅ H ₄ ) ₃ Er is used as the liquid material 14, and the gas temperature in the container 16 is about 130 ° C., which is considerably higher than normal temperature. It is conceivable that the temperature of the gas flowing in 28, particularly the gas temperature in the integrating flow meter 34, is slightly lower. Therefore, a temperature sensor (first temperature detection means) 54 is provided in the space 30 in the container 16, and a temperature sensor (second temperature detection means) is provided in the pipe 28 near the outlet or inlet of the integrating flow meter 34. ) 56 may be provided, and the above (4) may be corrected from the temperature detection values from these temperature sensors 54 and 56.
[0037]
That is, when the gas temperature in the container 16 detected by the temperature sensor 54 is T ₁ and the gas temperature in the integrating flow meter 34 detected by the temperature sensor 56 is T ₂ , the above equation (1) is
V ₁ = {(T ₁ +273) / (T ₂ +273)} Q / {(P ₁ −P ₂ ) × 10} (1) ′
The above equation (4) becomes
W = [V ₀ − {(T ₁ +273) / (T ₂ +273)} Q / {(P ₁ −P ₂ ) × 10}] × ρ + C (4) ′
It becomes. In the equation (4) ′, C is a correction value for each liquid measuring device in consideration of the volume in the pipe 28 and the like.
[0038]
Next, the liquid amount measuring apparatus 100 according to the second embodiment of the present invention shown in FIG. 2 will be described. In the liquid measuring apparatus 100 shown in FIG. 2, a buffer tank 102 is provided in the pipe 28 instead of the integrating flow meter 34 in FIG. 1, and a pressure sensor (second pressure) for detecting the pressure in the buffer tank 102 is used. 1 is different from the liquid measuring apparatus 10 shown in FIG. 1 in that an on-off valve 106 is attached to the pipe 28 on the outlet side of the buffer tank 102. Accordingly, the same or equivalent elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0039]
The control device 40 in the liquid measuring device 100 according to the second embodiment can recognize the gas pressure in the buffer tank 102 by receiving a signal from the pressure sensor 104. Further, the control device 40 can perform the open / close control of the open / close valve 106 as well as the open / close control of the other open / close valves 36, 38, 42, 44, 46.
[0040]
When measuring the liquid amount of the liquid material 14 in the container 16 using the liquid amount measuring device 100 having such a configuration, first, when the measurement start switch 48 is turned on, the control device 40 causes the on-off valves 36, 38, 42, A control signal is issued so that 44 and 46 are once closed and the on-off valve 106 is opened. Thereby, the inside of the buffer tank 102 becomes atmospheric pressure. The control device 40 calibrates the output value of the pressure sensor 104 to 0 MPa with a gauge pressure. The pressure output value at this time is P _B1 . Thereafter, the on-off valve 106 is closed.
[0041]
Next, the control device 40 sends a control signal to the on-off valve 36, opens it, and detects the gas pressure in the container 16 by a signal from the pressure sensor (first pressure detecting means) 32. Now, the pressure detection value and _{P A1,} also the value is assumed to be above the 0.3 MPa.
[0042]
If the controller 40 detects the gas pressure in the container 16 and opens the on-off valve 38, the pressure in the space 30 of the container 16 is higher than the pressure in the buffer tank 102. 28 flows into the buffer tank 102. Then, the control device 40 closes the on-off valve 38 and detects the gas pressure in the buffer tank 102 based on a signal from the pressure sensor 104 when a predetermined time has elapsed by a built-in timer (not shown). The pressure detection value at this time as the _{P B2,} assumed as 0.05 MPa. Note that the signal from the pressure sensor 104 may be monitored without using the timer, and the on-off valve 38 may be closed when the value reaches a preset value P _B2 (for example, 0.05 MPa). Simultaneously with the pressure detection by the pressure sensor 104, the control device 40 detects the gas pressure in the container 16 based on a signal from the pressure sensor 32. The pressure detection value at this time as the _{P A2,} and if 0.275MPa its value.
[0043]
The volume in the buffer tank 102 is known in advance. If the value is V _B (for example, 0.5 L), how much gas (L) is released from the container 16 in terms of atmospheric pressure. That is, what is the volume (gas volume) V ₁ of the space 30 in the container 16 can be calculated by the control device 40 using the following equation.
V ₁ = V _B × {(P _B2 −P _B1 ) × 10} / {(P _A1 −P _A2 ) × 10} (5)
[0044]
In the above specific example, P _A1 = 0.3 MPa, P _A2 = 0.275 MPa, P _B1 = 0 MPa, P _B2 = 0.05 MPa, V _B = 0.5 L, and this is applied to the equation (5). Thus, when V ₁ is obtained, 1L is obtained. Therefore, when the remaining liquid amount in the container 16 is represented by the accumulation V2,
V ₂ = V ₀ −V ₁ (6)
Therefore, if V ₀ is 3L, the remaining amount V ₂ is 2L.
[0045]
Further, by substituting Equation (5) into Equations (2) and (3), a value W representing the remaining amount of liquid in the container 16 by weight can be easily obtained from the following equation.
W = [V ₀ −V _B × {(P _B2 −P _B1 ) × 10} / {(P _A1 −P _A2 ) × 10}] × ρ (7)
[0046]
Similarly to the case of the first embodiment, temperature sensors 54 and 56 are provided in the container 16 and the buffer tank 102, and based on the detected values T ₁ and T ₂ from the temperature sensors 54 and 56, the equation If (7) is corrected,
W = [V ₀ − {(T ₁ +273) / (T ₂ +273)} × V _B × {(P _B2 −P _B1 ) × 10} / {(P ₁ −P ₂ ) × 10}] × ρ + C .. (7) '
It becomes. In addition, in Formula (5), (7), (7) ', the code | symbol which is not demonstrated in particular is synonymous with what was used by Formula (1)-(4) in 1st Embodiment.
[0047]
As described above, the gas in the container 16 is released into the buffer tank 102, and the liquid amount of the liquid material 14 in the container 16 can be accurately measured from the gas amount and the pressure change amount.
[0048]
【The invention's effect】
As described above, according to the present invention, the liquid amount of the liquid material remaining in the container can be accurately measured, and replenishment of the liquid material and replacement of the container itself can be performed at an appropriate timing. Work efficiency etc. can be improved.
[0049]
Further, according to the present invention, the liquid amount is measured from the exhaust gas amount and the pressure change. Does not occur at all.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a liquid amount measuring apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic explanatory view showing a liquid amount measuring apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10,100 ... Liquid quantity measuring device, 14 ... Liquid material, 16 ... Container, 18 ... Heater, 22, 24, 26, 28 ... Pipe, 30 ... Space in container, 32 ... Pressure sensor (1st pressure detection means) 34 ... Integral flow meter (gas emission amount detection means), 36, 38, 42, 44, 46, 106 ... Open / close valve, 40 ... Control device (arithmetic processing means), 54,46 ... Temperature sensor, 102 ... Buffer tank, 104... Pressure sensor (second pressure detecting means).

Claims (2)

A container for storing a liquid material, which is a device for measuring the amount of liquid material in the container that is capable of pumping the liquid material to a supply destination by feeding a pressurized gas. ,
Pressure detecting means for detecting a gas pressure in the container;
A gas discharge amount detecting means for detecting a discharge amount of the gas discharged from the container;
Calculation processing means for calculating the amount of liquid material in the container based on detection values from the pressure detection means and the gas discharge amount detection means;
With
The arithmetic processing means is
W = [V ₀ −Q / {(P ₁ −P ₂ ) × 10}] × ρ
(W: Volume of liquid material in container (kg)
V ₀ : the total volume of the container (L),
Q: Gas emission amount (L) from the measurement start time point to the measurement end time point detected by the gas discharge amount detection means,
P ₁ : gas pressure (MPa) in the container at the measurement start time detected by the pressure detection means,
P ₂ : gas pressure (MPa) in the container at the end of measurement detected by the pressure detection means,
ρ: Liquid density of liquid material (kg / L)
Based on the above, the liquid amount measuring device is characterized in that the liquid amount of the liquid material in the container is obtained by calculation .   The liquid amount measuring device according to claim 1, wherein the gas discharge amount detecting means is an integrating flow meter.

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