JP2002162284A - Level sensor, liquid container and liquid quantity detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a level sensor capable of effectively knowing the residual quantity of a container and a liquid container and a liquid quantity detecting method. SOLUTION: The level sensor 18 has a monitoring unit 23 connected to sensor probes 20a, 20b arranged in the liquid container 4. The monitoring unit 23 has a probe potential difference detection part 25 detecting the output potential difference of the sensor probes 20a, 20b, a level discrimination part 26 discriminating the level of liquid from the detected result, and a liquid use quantity calculation part 27 finding the accumulated bubbling time of gas for bubbling from the detected result of the probe potential difference detection part 25, and a liquid use quantity calculation part 27 calculating the use quantity and the residual quantity of liquid in the liquid container 4 from the accumulated bubbling time and liquid use quantity data per previously stored bubbling unit time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid level sensor used in a so-called liquid source bubbling system,
The present invention relates to a liquid container and a liquid amount detection method.

[0002]

2. Description of the Related Art In a so-called liquid source bubbling system in which a bubbling gas is introduced into a liquid container to generate bubbling in a liquid to generate a desired process gas, a liquid level sensor is sometimes used. . As this liquid level sensor, for example, a sensor that directly immerses a sensor probe in a liquid contained in a container and detects the liquid level of the liquid is known.

[0003]

When actually measuring the liquid level of the liquid in the container using the liquid level sensor,
It is desirable to be able to grasp not only whether the liquid level of the liquid is higher or lower than a predetermined level, but also how much liquid remains in the container in an analog manner. Is not provided.

An object of the present invention is to provide a liquid level sensor, a liquid container, and a liquid amount detecting method capable of effectively knowing the remaining amount of liquid in a container.

[0005]

The present inventors have made intensive studies and as a result, in the liquid source bubbling system, the level of the liquid contained in the liquid container fluctuates violently during bubbling of the bubbling gas. Therefore, by detecting the fluctuation of the liquid level of the liquid, the bubbling time of the bubbling gas can be grasped, and under a certain condition, the amount of the liquid used in the liquid container can be calculated from the bubbling time. The present invention has been completed.

That is, the present invention relates to a liquid level sensor for detecting a liquid level of a liquid contained in a liquid container into which a bubbling gas is introduced, and a self-heating sensor disposed in the liquid container. A probe for measuring the temperature between the self-heating sensor probe and the temperature-measuring sensor probe; and a bubbling time for the bubbling gas based on the temperature difference. And a calculating means for calculating the used amount of the liquid in the liquid container.

In the present invention constructed as described above, when bubbling of the bubbling gas occurs, the liquid in the liquid container is agitated, so that the temperature difference (output) between the self-heating sensor probe and the temperature measurement sensor probe. Potential difference) is 0
Get closer to. Therefore, the calculating means calculates the bubbling time of the bubbling gas using the characteristic. Also, since the amount of liquid used per unit time of bubbling is considered to be almost constant, if the amount of liquid used per unit time of bubbling is known, the data and the bubbling time of the bubbling gas are used to determine the amount of liquid used in the liquid container. The usage can be calculated. Since the total amount of the liquid in the liquid container in the initial state is predetermined, the current remaining amount of the liquid can be easily known by knowing the used amount of the liquid.

The present invention also relates to a liquid level sensor for detecting a liquid level of a liquid contained in a liquid container into which a bubbling gas is introduced, wherein the self-heating sensor is disposed in the liquid container. A probe and a temperature measurement sensor probe; a temperature difference detection means for detecting a temperature difference between the self-heating sensor probe and the temperature measurement sensor probe; and a liquid level determination for determining a liquid level of the liquid based on the temperature difference. Means for calculating the bubbling time of the bubbling gas based on the temperature difference, and calculating means for calculating the amount of liquid used in the liquid container from the bubbling time.

In the present invention having the above-described structure, when bubbling of the bubbling gas occurs, the liquid in the liquid container is agitated, so that the temperature difference (output) between the self-heating sensor probe and the temperature measurement sensor probe. Potential difference) is 0
Get closer to. Therefore, the calculating means calculates the bubbling time of the bubbling gas using the characteristic. Also, since the amount of liquid used per unit time of bubbling is considered to be almost constant, if the amount of liquid used per unit time of bubbling is known, the data and the bubbling time of the bubbling gas are used to determine the amount of liquid used in the liquid container. The usage can be calculated. Since the total amount of the liquid in the liquid container in the initial state is predetermined, the current remaining amount of the liquid can be easily known by knowing the used amount of the liquid. Thus, according to the present liquid level sensor, not only is the liquid level of the liquid higher or lower than a predetermined level, but also
The amount of liquid remaining in the container can be grasped in an analog manner. In addition, since the remaining amount of the liquid can be effectively known as described above, only one set of the sensor probe for self-heating and the sensor probe for temperature measurement is required, and the configuration of the liquid level sensor can be simplified.

Preferably, the calculating means stores in advance liquid use amount data per unit time of bubbling, and calculates the use amount of liquid in the liquid container from the bubbling time of the bubbling gas and the liquid use amount data per unit time of bubbling. Calculate the amount. In this case, the amount of liquid used can be obtained without calculating the amount of liquid used per unit time of bubbling by the calculating means.

Preferably, the calculating means obtains the bubbling time by measuring a time from a temperature difference falling timing period to a temperature difference rising timing period.

Preferably, the apparatus further comprises display means for displaying the amount of liquid used or the remaining amount of liquid in the liquid container calculated by the calculation means. Thereby, the operator can immediately grasp the used amount or the remaining amount of the liquid by looking at the display means.

Further, the liquid container of the present invention comprises a container main body for containing a liquid, a gas introduction portion provided in the container main body, for introducing a bubbling gas into the container main body, and a bubbling gas provided in the container main body. A gas deriving unit for guiding the gas generated by bubbling to the outside of the container body, a self-heating sensor probe and a temperature measuring sensor probe disposed in the container body, a self-heating sensor probe and a temperature measuring sensor A temperature difference detecting means for detecting a temperature difference from a probe; and a calculating means for obtaining a bubbling time of a bubbling gas based on the temperature difference and calculating a liquid usage amount from the bubbling time. It is.

By providing the self-heating sensor probe and the temperature measuring sensor probe, the temperature difference detecting means, and the calculating means, the remaining amount of the liquid in the container body can be effectively grasped as described above. Can be.

Preferably, the apparatus further includes a heater for heating the liquid contained in the container body, and a temperature sensor for detecting the temperature of the liquid in the container body. As a result, a process gas having an appropriate temperature can be generated.

Preferably, the gas outlet is connected to a film forming apparatus. In this case, the number of substrates to be processed can be ascertained by obtaining the total bubbling time of the bubbling gas in the substrate film forming process.

Further, in the liquid amount detecting method according to the present invention, the self-heating sensor probe and the temperature measuring sensor probe are arranged in a liquid container into which the bubbling gas is introduced, and the self-heating sensor probe and the temperature measuring sensor are arranged. A temperature difference from a probe is detected, a bubbling time of a bubbling gas is obtained based on the temperature difference, and a usage amount of a liquid stored in a liquid container is calculated from the bubbling time. Thereby, as described above, the remaining amount of the liquid in the container can be effectively grasped.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid level sensor according to the present invention,
A preferred embodiment of a liquid container and a liquid amount detection method will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a film forming system including an embodiment of a liquid container according to the present invention. In FIG. 1, a film forming system 1 forms a titanium nitride (TiN) film on the surface of a semiconductor wafer W. The film forming system 1 includes a CVD apparatus 2 and a CV
And a liquid container 4 connected to the D apparatus 2 via a gas pipe 3.

The CVD apparatus 2 has a processing chamber 5, and the pressure in the processing chamber 5 is reduced by a vacuum pump 6. A pedestal 7 for supporting the wafer W is disposed in the processing chamber 5, and the pedestal 7 is provided with a heater 8 for heating the wafer W. Above the pedestal 7, a gas distribution plate 9 is arranged.
The gas distribution plate 9 is connected to the gas pipe 3, and receives tetradimethylaminotitanium (TDMAT) gas, which is a film forming gas (process gas) sent from the liquid container 4,
It is blown uniformly toward the wafer W. Then, TDMAT
Is thermally decomposed on the heated wafer W, and a film forming process is performed.

A liquid container 4 connected to such a CVD apparatus 2 contains a tetradimethylaminotitanium liquid (TDMAT).
(Liquid) 50 is provided. The container body 12 is preferably made of a material such as stainless steel having high strength and having corrosion resistance to the TDMAT liquid 50.

A gas introduction pipe 13 for introducing helium (He) gas into the container body 12 is provided in the lid 12a of the container body 12. The gas introduction pipe 13 extends to near the bottom surface of the container body 12, and is provided with a TDMAT liquid 50.
He gas bubbling is caused to occur therein.
The TDMAT liquid 50 is vaporized by the bubbling of the He gas, and a TDMAT gas as a film forming gas is generated. The lid 12a of the container body 12 has a TDMAT
A gas outlet pipe 14 for extracting gas is provided, and the gas pipe 3 is connected to the gas outlet pipe 14.
Note that a plurality of open / close valves 15 are provided in the gas pipe 3.

Outside the container body 12, a heater 16 for heating the TDMAT liquid 50 in the container body 12 is arranged. In addition, a temperature sensor 17 for detecting the temperature of the TDMAT liquid 50 is disposed in the container body 12. Then, the TDMAT liquid 50 is heated by the heater 16 while monitoring the temperature of the TDMAT liquid 50 by the temperature sensor 17. At this time, the temperature of the TDMAT liquid 50 is set to a temperature (for example, 50 degrees) that stabilizes the film forming process by the CVD apparatus 2.

The liquid container 4 is provided with a heat-sensitive liquid level sensor 18 for detecting the liquid level of the TDMAT liquid 50. The liquid level sensor 18 has a base 19 that is detachably attached to the lid 12 a of the container body 12. A pair of sensor probes 20a, 20b is attached to the lower surface of the base portion 19. The tip ends of the sensor probes 20a, 20b extend downward in the container body 12 and are immersed in the TDMAT liquid 50. It is arranged so that. The sensor probes 20a and 20b are connected to a monitoring unit 23 via a lead wire 22. Such a sensor probe 20
FIG. 2 shows the principle of the liquid level detection by a and 20b.

In FIG. 2, the sensor probes 20a, 20
Reference numeral 0b has a stainless steel sheath (not shown), and a platinum temperature measuring resistor 24 having stable temperature characteristics is provided inside the sheath at the distal ends of the sensor probes 20a and 20b.
a and 24b are pasted. The platinum resistance temperature detectors 24 a and 24 b are connected to the lead wire 22. The sensor probe 20a is a high-temperature sensor probe for self-heating, and the sensor probe 20b is a low-temperature sensor probe for temperature measurement. Then, these sensor probes 20a,
The liquid level of the TDMAT liquid is detected by using the temperature difference generated between 20b.

More specifically, both sensor probes 20a, 20a
0b (platinum resistance thermometers 24a, 24b) is TD
When the liquid is in the MAT liquid (see liquid level A in FIG. 2), the heat generated by the self-heating sensor probe 20a is T
Escapes into the DMAT solution and heat diffusion occurs. For this reason, the temperature difference between the sensor probes 20a and 20b is reduced, and the difference between the resistance values of the platinum temperature measuring resistors 24a and 24b is reduced. In actual measurement, the platinum resistance thermometer 24
The difference between the resistances of the platinum resistance thermometers 24a, 24b
4b (potential difference between the sensor probes 20a and 20b). On the other hand, the sensor probe 20
a, 20b (Platinum resistance temperature detectors 24a, 24b)
Is present not in the TDMAT liquid but in the TDMAT gas (see liquid level B in FIG. 2), of the heat generated by the self-heating sensor probe 20a, very little heat escapes into the TDMAT gas. For this reason, the temperature difference between the sensor probes 20a and 20b increases, so that the difference between the resistance values of the platinum resistance temperature detectors 22a and 22b (the output potential difference between the sensor probes 20a and 20b) increases. As described above, due to the output potential difference between the sensor probes 20a and 20b, the tip ends of the sensor probes 20a and 20b are set to TDMA.
It can be seen whether it is in the T liquid or in the TDMAT gas. When the tip of the sensor probe 20a, 20b is in the TDMAT gas, the TD
It is determined that the amount of the MAT liquid is small and the liquid level of the TDMAT liquid is at an empty level.

The process of detecting the liquid level of the TDMAT liquid is performed by the monitoring unit 23. The monitoring unit 23, as shown in FIG.
A liquid level determining unit 26, a liquid usage calculating unit 27,
And a display unit 28.

The probe potential difference detecting section 25 detects the output potential difference (temperature difference) of the sensor probes 20a and 20b described above. The liquid level discriminating unit 26 includes the sensor probe 2
Based on the output potential difference between 0a and 20b, it is determined whether the liquid level of the TDMAT liquid is at an empty level.

The liquid use amount calculation unit 27 includes the sensor probe 2
The bubbling time of He gas is obtained based on the output potential difference between 0a and 20b, and the used amount and remaining amount of the TDMAT solution are calculated from the bubbling time. The display unit 28 uses the TDM
Whether the liquid level of the AT liquid is at the empty level or not
In addition to displaying an ED or the like, the used amount and the remaining amount of the TDMAT solution are digitally displayed, for example. By looking at such a display unit 28, the current usage amount and remaining amount of the TDMAT solution can be immediately grasped.

If He gas bubbling occurs while the TDMAT liquid is contained in the container body 12, the TDMAT liquid in the container body 12 vibrates violently, so that the TDMAT liquid is agitated and the self-heating sensor is used. The temperature difference (output potential difference) between the probe 20a and the temperature measuring sensor probe 20b approaches zero. An example of this is shown in FIG.

In FIG. 3, when both the tip of the self-heating sensor probe 20a and the tip of the temperature measurement sensor probe 20b are in the TDMAT solution, the two probe probes 20a and 20a,
The output potential difference of Ob is a standard level in the liquid (about 0.1 in the figure).
2V). When bubbling of He gas occurs in this state, the output potential difference between the two sensor probes 20a and 20b sharply drops to 0V in about 5 seconds. And He
When gas bubbling stops, both sensor probes 20
The output potential difference between a and 20b rises from 0 V, and returns to the above-mentioned liquid standard level after a few seconds.

The liquid usage calculator 27 calculates the usage of the TDMAT liquid by utilizing such bubbling characteristics.
FIG. 5 shows a procedure for calculating the amount of TDMAT solution used by the solution usage calculator 27.

In the figure, first, an output signal of the probe potential difference detecting section 25 is input (step 101). Then, it is determined whether or not He gas bubbling has occurred based on the output potential difference between the sensor probes 20a and 20b (step 102). At this time, if the output potential difference between the sensor probes 20a and 20b drops by a predetermined amount (for example, 0.01 V) from the liquid standard level, it is determined that the He gas bubbling has occurred. In addition, the sensor probe 20
Output potential difference between a and 20b is the lowest level (0 V in FIG. 4)
When a predetermined amount (e.g., 0.01 V) is exceeded, it is determined that bubbling of He gas has been completed. Note that a period during which the output potential difference between the sensor probes 20a and 20b falls by a predetermined amount from the submerged standard level is called a fall timing period,
A period during which the output potential difference between the sensor probes 20a and 20b rises by a predetermined amount from the lowest level is referred to as a rising timing period. Accordingly, the sensor probes 20a, 20
It is determined that bubbling of He gas has occurred during the period from the fall timing period to the rise timing period of the output potential difference of 0b.

When it is determined in step 102 that bubbling of He gas has occurred, measurement of the bubbling time of He gas is started (step 103). afterwards,
Returning to step 101, while the bubbling is occurring, the measurement of the bubbling time is continuously performed. On the other hand, step 102
If it is determined that bubbling has not occurred, it is determined whether the bubbling time is being measured (step 104). When it is determined that the bubbling time is being measured, the measurement of the bubbling time is stopped (step 105). Thus, the bubbling time of one bubbling period is calculated. The bubbling time is a time from the start of the fall timing period of the output potential difference between the sensor probes 20a and 20b to the start of the rise timing period, or from the end of the fall timing period of the output potential difference of the sensor probes 20a and 20b. It is the time until the end of the rising timing period. Subsequently, the total bubbling time is calculated by adding the bubbling time to the total bubbling time up to now (step 106).

Subsequently, the current use amount and remaining amount of the TDMAT solution are calculated from the cumulative bubbling time and the liquid use amount data per unit time of bubbling stored in a memory (not shown) (step 107). Here, the liquid consumption data per unit time of bubbling is, for example,
It is obtained in advance by performing a bubbling test using an arbitrary liquid container. Further, the remaining amount of the TDMAT liquid is calculated by subtracting the current usage amount from the initial state of the liquid container 4, that is, the total liquid amount when the TDMAT liquid is full. Subsequently, the usage amount data and the remaining amount data of the TDMAT solution are output to the display unit 28, and the current TDMAT solution is output.
The display unit 28 displays the used amount and the remaining amount of the T solution.

In such a liquid use amount calculating section 27, since the volume and the like of the container body 12 are known in advance, T
It is also possible to calculate the liquid level of the TDMAT liquid in addition to the used amount or the remaining amount of the DMAT liquid and display the liquid level on the display unit 28. It is also possible to count the number of processed wafers W for the currently used liquid container 4 based on the cumulative bubbling time of the He gas, and display it on the display unit 28.

As described above, in the present embodiment, He is set based on the output potential difference between the sensor probes 20a and 20b.
Since the cumulative bubbling time of the gas is calculated and the used amount or the remaining amount of the TDMAT liquid is calculated from the cumulative bubbling time, not only whether the liquid level of the TDMAT liquid is at an empty level, but also the TDMA in
How much T liquid remains can also be grasped in an analog manner. Therefore, the usability of the liquid level sensor is improved.

Further, since the remaining amount of the TDMAT solution can be known in an analog manner as described above, it is basically sufficient to provide one set of the self-heating sensor probe 20a and the temperature measurement sensor probe 20b. This simplifies the structure of the liquid level sensor.

The present invention is not limited to the above embodiment. For example, the liquid container of the above embodiment is
But is intended to reserving the TDMAT liquid for forming a titanium nitride film by CVD process, store liquid is not particularly limited thereto, TEOS or TiCl ₄ or the like,
Any material used in the liquid source bubbling system as described above can be used. Further, the supply destination of the process gas generated by bubbling is not limited to the CVD apparatus. Further, the gas for causing bubbling is not limited to He gas, but may be argon gas or the like.

[0040]

According to the present invention, the bubbling time of the bubbling gas is calculated based on the temperature difference between the sensor probe for self-heating and the sensor probe for temperature measurement, and the amount of liquid used in the liquid container is calculated from the bubbling time. Is calculated, it is possible to effectively know how much liquid remains in the container. This makes it easier to use the liquid level sensor.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a film forming system including an embodiment of a liquid container according to the present invention.

FIG. 2 is a diagram showing a principle for detecting a liquid level of a liquid by a liquid level sensor shown in FIG. 1;

FIG. 3 is a diagram showing a configuration of a monitoring unit shown in FIG.

4 is a characteristic diagram showing a change in an output potential difference between a sensor probe for self-heating and a sensor probe for temperature measurement which occurs when bubbling of a bubbling gas occurs in the liquid container shown in FIG.

FIG. 5 is a flowchart showing a procedure of calculating a liquid usage amount by a liquid usage amount calculation unit shown in FIG. 3;

[Explanation of symbols]

2 CVD apparatus (film forming apparatus), 4 liquid container, 12 container main body, 13 gas introduction pipe (gas introduction section), 14 gas introduction pipe (gas introduction section), 16 heater, 17 temperature sensor , 18: liquid level sensor, 20a: high temperature sensor probe for self-heating, 20b: low temperature sensor probe for temperature measurement, 2
5 ... Probe potential difference detecting section (temperature difference detecting means), 26 ...
Liquid level determining section (liquid level determining section), 27: liquid usage calculating section (calculating section), 28: display section (displaying section),
50: TDMAT liquid (liquid).

Continuing on the front page (72) Inventor Yoshikatsu Shirai 14-3 Shinzumi, Narita-shi, Chiba Pref. Within Applied Materials Japan Co., Ltd. Applied Materials Japan Co., Ltd. F term (reference) 2F014 CA10 4K030 AA11 AA16 BA18 BA38 CA04 CA12 EA01 KA25 KA39 5F045 AA03 AC08 AC17 EE03 GB05 GB16

Claims (9)

[Claims] 1. A liquid level sensor for detecting a liquid level of a liquid contained in a liquid container into which a bubbling gas is introduced, comprising: a self-heating sensor probe disposed in the liquid container; A temperature measurement sensor probe, temperature difference detection means for detecting a temperature difference between the self-heating sensor probe and the temperature measurement sensor probe, and determining a bubbling time of the bubbling gas based on the temperature difference. A liquid level sensor comprising: a calculating unit configured to calculate a usage amount of the liquid in the liquid container from a bubbling time. 2. A liquid level sensor for detecting a liquid level of a liquid contained in a liquid container into which a bubbling gas is introduced, comprising: a sensor probe for self-heating disposed in the liquid container; A temperature measurement sensor probe; a temperature difference detection means for detecting a temperature difference between the self-heating sensor probe and the temperature measurement sensor probe; and a liquid level for determining a liquid level of the liquid based on the temperature difference. A liquid level sensor comprising: a level determining unit; and a calculating unit that calculates a bubbling time of the bubbling gas based on the temperature difference, and calculates a usage amount of the liquid in the liquid container from the bubbling time. 3. The computing means stores in advance liquid use amount data per unit time of bubbling, and uses the bubbling time of the bubbling gas and the liquid use amount data per unit time of bubbling to calculate the amount of liquid used in the liquid container. The liquid level sensor according to claim 1, wherein the liquid usage amount is calculated. 4. The bubbling time according to claim 1, wherein the calculating means calculates the bubbling time by measuring a time from a falling timing period of the temperature difference to a rising timing period of the temperature difference. Liquid level sensor as described. 5. The liquid level sensor according to claim 1, further comprising a display unit for displaying the used amount of the liquid in the liquid container or the remaining amount of the liquid calculated by the calculation unit. 6. A container main body for storing a liquid, a gas introduction portion provided in the container main body, for introducing a bubbling gas into the container main body, and a gas introduction portion provided in the container main body and bubbling the bubbling gas. A gas deriving unit that guides the generated gas to the outside of the container main body; a self-heating sensor probe and a temperature measuring sensor probe disposed in the container main body; the self-heating sensor probe and the temperature measuring device A liquid container comprising: a temperature difference detection unit that detects a temperature difference from a sensor probe; and a calculation unit that determines a bubbling time of the bubbling gas based on the temperature difference, and calculates a usage amount of the liquid from the bubbling time. . 7. The liquid container according to claim 6, further comprising a heater for heating the liquid contained in the container body, and a temperature sensor for detecting a temperature of the liquid in the container body. 8. The liquid container according to claim 6, wherein the gas outlet is connected to a film forming apparatus. 9. A self-heating sensor probe and a temperature measurement sensor probe are arranged in a liquid container into which bubbling gas is introduced, and a temperature difference between the self-heating sensor probe and the temperature measurement sensor probe is detected. Then, a bubbling time of the bubbling gas is obtained based on the temperature difference, and a used amount of the liquid stored in the liquid container is calculated from the bubbling time.