JP2002131113A - Sensor, liquid storage container and bubbling detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor, a liquid storage container and a bubbling detection method permitting effective monitoring of liquid condition in a container. SOLUTION: A liquid level sensor 18 is provided with four sensor probes 20a-21b and a monitoring unit 23 connected with those probes. The monitoring unit 23 contains a probe potential difference detecting section 25 detecting output potential differences in both sensor probes 20a/20b and 21a/21b, and a liquid level detecting section detecting fluid liquid level from the above detection result. Additionally the monitoring unit 23 contains a bubbling detection pulse generating section 28 detecting bubbling generation of the gas for bubbling from the detection result of the probe potential difference detecting section 25 to generate pulse signals and a pulse counter 29 counting the number of pulses generated on this bubbling detection pulse generating section 28, knowing the number of times of bubbling period in the gas for bubbling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor, a liquid storage container, and a bubbling detection method used in a so-called liquid source bubbling system.

[0002]

2. Description of the Related Art A sensor used in a so-called liquid source bubbling system for generating a desired process gas by introducing a bubbling gas into a liquid storage container to generate bubbling in the liquid includes, for example, an in-vessel sensor. One that detects the liquid level of the liquid is known.

[0003]

However, in the liquid source bubbling system as described above, from the viewpoint of quality control, not only the presence or absence of the liquid in the container but also the degree of the reduction of the liquid is normal. It is also desired to be able to monitor whether or not it is possible.

[0004] It is an object of the present invention to provide a sensor, a liquid storage container and a bubbling detection method which can effectively monitor the state of liquid in the container.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that in the liquid source bubbling system, the liquid level in the container fluctuates violently during bubbling of the bubbling gas. The present inventors have found that the number of times of bubbling of the bubbling gas can be grasped by detecting the fluctuation of the liquid level in the present invention, thereby completing the present invention.

That is, the sensor of the present invention comprises a self-heating sensor probe and a temperature measurement sensor probe arranged in a liquid storage container into which bubbling gas is introduced.
Temperature difference detecting means for detecting the temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and bubbling counting means for counting the number of times of the bubbling period of the bubbling gas based on the temperature difference between the two sensor probes. It is characterized by having.

In the present invention constructed as described above, when bubbling of the bubbling gas occurs, the liquid in the liquid storage container is agitated, so that the temperature difference between the sensor probe for self-heating and the sensor probe for temperature measurement ( Output potential difference)
Approaches zero. Therefore, it is possible to count the number of times of the bubbling period of the bubbling gas by counting the number of times the temperature difference between the two sensor probes approaches 0 by the bubbling counting means. As a result, it is possible to grasp how the liquid in the container is reduced. For example,
By knowing how many times the bubbling period has occurred between the time when the liquid in the liquid storage container changes from the full state to the empty state, it is possible to determine whether the liquid in the container is normally reduced. Thus, the state of the liquid in the container can be monitored effectively.

The present invention also relates to a sensor for detecting a liquid level of a liquid stored in a liquid storage container into which a bubbling gas is introduced, and a self-heating sensor disposed in the liquid storage container. A probe and a temperature measuring sensor probe; a temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and determining a liquid level of the liquid based on a temperature difference between the two sensor probes. And a bubbling counting means for counting the number of bubbling periods of the bubbling gas based on a temperature difference between the two sensor probes.

When the liquid level in the liquid storage container is measured using such a sensor, the liquid in the container is agitated during the bubbling of the bubbling gas.
The temperature difference (output potential difference) between the self-heating sensor probe and the temperature measurement sensor probe approaches zero. Therefore, it is possible to count the number of times of the bubbling period of the bubbling gas by counting the number of times the temperature difference between the two sensor probes approaches 0 by the bubbling counting means. As described above, the present sensor not only detects the liquid level of the liquid in the container by the liquid level determination means, but also detects the number of times of the bubbling period of the bubbling gas by the bubbling counting means. Can be monitored effectively.

Preferably, the bubbling counting means includes: a pulse generating means for generating a pulse signal when a temperature difference between the self-heating probe sensor and the temperature measuring probe sensor is reduced by a predetermined amount; A pulse counter for counting the number. Thereby, the bubbling counting means can be realized with a simple configuration, which is advantageous in cost.

Preferably, the apparatus further comprises display means for displaying the number of bubbling periods counted by the bubbling counting means. Thus, the operator can immediately grasp the number of bubbling periods by looking at the display means.

Further, preferably, a plurality of probe sensor groups each including a self-heating probe sensor and a temperature measurement probe sensor are provided, and the tip positions of the probe sensor groups in each group are different. Thereby, the degree of reduction of the liquid in the container can be grasped stepwise.

Further, the liquid storage container of the present invention is provided with a container main body for storing liquid, a gas introduction portion provided on the container main body, for introducing a bubbling gas into the container main body, and a gas introduction portion provided on the container main body for bubbling. A gas deriving unit for deriving a gas generated by gas bubbling to the outside of the container body,
A self-heating sensor probe and a temperature measurement sensor probe arranged in the container body, a temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measurement sensor probe, and a temperature difference between the two sensor probes. Bubbling counting means for counting the number of bubbling periods of the bubbling gas based on the above.

By providing the self-heating sensor probe and the temperature measuring sensor probe, the temperature difference detecting means, and the bubbling counting means as described above, it is possible to grasp how the liquid in the container body is reduced as described above.

Preferably, the apparatus further includes a heater for heating the liquid stored in the container body, and a temperature sensor for detecting a 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, by counting the number of bubbling periods of the bubbling gas in the substrate film forming process, the number of processed substrates can be ascertained.

Further, in the bubbling detection method of the present invention, a self-heating sensor probe and a temperature measurement sensor probe are arranged in a liquid storage container into which bubbling gas is introduced, and a temperature difference between these sensor probes is detected. The number of times of the bubbling period of the bubbling gas is counted based on the temperature difference. Thereby, as described above, it is possible to grasp how the liquid in the container is reduced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a sensor, a liquid storage container and a bubbling detection method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram schematically showing a film forming system including an embodiment of a liquid storage container according to the present invention. In FIG. 1, a film forming system 1 includes a semiconductor wafer W
A CVD device 2 and a liquid storage container 4 connected to the CVD device 2 via a gas pipe 3 are provided for forming a titanium nitride (TiN) film on the surface of the device.

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 a film forming gas (process gas) sent from the liquid storage container 4.
Is uniformly blown toward the wafer W. Then, the TDMAT that has reached the heated wafer W is thermally decomposed, and a film forming process is performed.

A liquid storage container 4 connected to such a CVD apparatus 2 is provided with a tetradimethylaminotitanium liquid (TDM).
(AT liquid) 50 is stored. 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. Further, the gas outlet pipe 1 is provided on the lid 12a of the container body 12.
The gas outlet pipe 14 is provided with the gas pipe 3
Is connected. 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. 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 solution 50 is set to a temperature (for example, 50
Degrees).

In such a liquid storage container 4, TDMA
A heat-sensitive liquid level sensor 18 for detecting the liquid level of the T liquid 50 is provided. The liquid level sensor 18 has a base 19 that is detachably attached to the lid 12 a of the container body 12. On the lower surface of the base portion 19, two sensor probe groups including sensor probes 20a and 20b for detecting an empty level and sensor probes 21a and 21b for detecting a warning level are attached.

These sensor probes 20a-21b
Is disposed so that the tip side extends downward in the container body 12 and is immersed in the TDMAT liquid 50.
Here, the sensor probes 21a, 2 for warning level detection
The height position of the tip of 1b is higher than the height position of the tip of the sensor probes 20a and 20b for detecting the empty level. Further, the sensor probes 20 a to 21 b are connected to the monitoring unit 23 via the lead wire 22. FIG. 2 shows the principle of liquid level detection by such sensor probes 20a to 21b.

In FIG. 1, sensor probes 20a, 20a
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 configured as a high-temperature sensor probe for self-heating, and the sensor probe 20b is configured as a low-temperature sensor probe for temperature measurement. Then, the liquid level of the TDMAT liquid is detected using the temperature difference generated between the sensor probes 20a and 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.

Further, among the sensor probes 21a and 21b for detecting a warning level, the sensor probe 21a is configured as a high-temperature sensor probe for self-heating, and the sensor probe 21b is configured as a low-temperature sensor probe for temperature measurement. The configuration of the sensor probes 21a and 21b is the same as that of the sensor probes 20a and 20b. By providing the two sets of sensor probes 20a, 20b and 21a, 21b in this manner, the degree of decrease of the TDMAT liquid in the container body 12 can be grasped stepwise.

That is, when the tip portions of the sensor probes 21a and 21b are in the TDMAT liquid, the TDMAT liquid is sufficiently left in the container body 12, and the liquid level becomes the remaining level. Although the tip portions of the sensor probes 20a and 20b are in the TDMAT liquid, the sensor probes 21a and 21b
When the tip of b is in the TDMAT gas, the amount of the TDMAT liquid remaining in the container body 12 is small, and the liquid level becomes the warning level. When the tips of the sensor probes 20a and 20b are in the TDMAT gas, the container body 12
There is almost no TDMAT liquid remaining inside, and the liquid level becomes an empty level.

The determination of 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 determination unit 26 and a liquid level display unit 27.

The probe potential difference detecting section 25 detects the output potential difference (temperature difference) of the above-mentioned empty level detecting sensor probes 20a and 20b and the warning level detecting sensor probes 21a and 21b, respectively. Liquid level determination unit 26
Determines whether the liquid level of the TDMAT liquid is at the above-described remaining level, warning level, or empty level based on the output potential difference between the sensor probes 20a and 20b and the output potential difference between the sensor probes 21a and 21b. I do. The probe potential difference detection unit 25 and the liquid level determination unit 26 are configured by, for example, an operational amplifier. The liquid level indicator 27 indicates the liquid level of the TDMAT liquid (the remaining level, the warning level, and the empty level).
Is displayed by an LED or the like.

The monitoring unit 23 is provided with the TD
In addition to the main function of detecting the liquid level of the MAT liquid,
In order to also have a function of detecting the number of e-gas bubbling periods, a bubbling detection pulse generation unit 28, a pulse counter 29, and a count display unit 30 are provided.

If He gas bubbling occurs in a state where 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 stirred and the self-heating sensor is used. Output potential difference (temperature difference) between probe and sensor probe for temperature measurement
Approaches zero. An example of this is shown in FIG.

In the same figure, the tip of the self-heating sensor probe and the tip of the temperature measurement sensor probe are both TDMA.
When bubbling of He gas occurs in the T liquid, the output potential difference between the two sensor probes drops sharply and becomes 0 V in about 5 seconds. Then, when the bubbling of the He gas is stopped, the output potential difference between the two sensor probes rises, and returns to the potential difference in a state where both tip portions of the both sensor probes are in the TDMAT solution.

The monitoring unit 23 detects the number of times of the bubbling period of He gas using such bubbling characteristics. That is, the bubbling detection pulse generation unit 28 receives the output signal of the probe potential difference detection unit 25 and detects whether the output potential difference between the self-heating sensor probe and the temperature measurement sensor probe has decreased by a predetermined amount, A pulse signal is generated by detecting the occurrence of bubbling of He gas. At this time, as the signal used for detecting the occurrence of bubbling, it is preferable to use a signal related to the output potential difference between the empty level detection sensor probes 20a and 20b among the output signals of the probe potential difference detection unit 25. Note that the bubbling detection pulse generation unit 28
For example, it is configured by an operational amplifier or the like.

The pulse counter 29 counts the number of pulses generated by the bubbling detection pulse generator 28, that is, the number of bubbling periods. Count display section 30
Causes the number of pulses counted by the pulse counter 29 to be digitally displayed, for example. Thereby, the operator can grasp the number of times of the bubbling period of He gas with respect to the liquid storage container 4 currently being used, by looking at the display of the count display unit 30.

In the film forming process by the CVD apparatus 2, the bubbling time required for forming one wafer W is known in advance because the bubbling time of one He gas is almost fixed. ing. Therefore, the monitoring unit 23 may count the number of processed wafers W in the currently used liquid storage container 4 in addition to the number of times of the He gas bubbling period, and digitally display the number on the count display unit 30. It is possible.

In the present embodiment as described above, the liquid level sensor 18 has a function of detecting the number of times of the bubbling period of He gas based on the output potential difference between the self-heating sensor probe and the temperature measurement sensor probe. Since it is provided, not only the presence or absence of the TDMAT liquid in the container body 12 but also the container body 1
It can also be grasped whether the TDMAT solution in 2 is normal or not. For example, in the case where the TDMAT liquid in the liquid storage container 4 runs out despite the fact that the number of He gas bubbling periods for one liquid storage container 4 is smaller than usual, leakage of the TDMAT liquid occurs. It can be determined that some abnormality has occurred, for example, The TD in the liquid storage container 4 using such a liquid level sensor 18
Since the liquid level of the MAT liquid is detected, the liquid storage container 4
The state of the TDMAT solution in the inside can be monitored effectively, which is advantageous for quality control.

The present invention is not limited to the above embodiment. For example, in the liquid level sensor of the above-described embodiment, the bubbling counting means for detecting the number of times of the bubbling period of the He gas is configured by the bubbling detection pulse generation unit 28 and the pulse counter 29. A converter, a CPU, and the like may be provided, and may be configured in software with a main function of detecting the liquid level of the TDMAT liquid.

Further, in the above embodiment, two sets of the probe sensor group including the self-heating probe sensor and the temperature measuring probe sensor are provided, but only one set of the sensor probe group may be provided. Three or more sets of groups may be provided, and the tip positions may be different for each set.

Further, the liquid storage container of the above embodiment is
A TDMAT liquid for forming a titanium nitride film by a CVD process is stored. However, the liquid to be stored is not particularly limited.
Anything such as ₄ used in the liquid source bubbling system as described above may 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.

[0042]

According to the present invention, the bubbling counting means for counting the number of bubbling periods of the bubbling gas is provided based on the temperature difference between the self-heating sensor probe and the temperature measurement sensor probe. It is possible to effectively monitor the state of the liquid in the storage container.
As a result, a system abnormality or the like can be immediately grasped, which is advantageous in quality control.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a film forming system including an embodiment of a liquid storage 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 that occurs when bubbling of a bubbling gas occurs in the liquid storage container shown in FIG.

[Explanation of symbols]

2 ... CVD apparatus (film forming apparatus), 4 ... liquid storage container, 12
... container body, 13 ... gas introduction pipe (gas introduction part), 14 ...
Gas outlet pipe (gas outlet), 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, 21a high-temperature sensor probe for self-heating , 21b ...
Low temperature sensor probe for temperature measurement, 25: probe potential difference detecting section (temperature difference detecting section), 26: liquid level determining section (liquid level determining section), 28: bubbling detection pulse generating section (pulse generating section, bubbling counting section) ), 29
... Pulse counter (bubbling counting means), 30 ... Count display part (display means), 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 CA02 5F045 AA06 AC07 AC17 EB03 EE03 EK05 EK07 GB05 GB15

Claims (9)

[Claims] 1. A self-heating sensor probe and a temperature measurement sensor probe disposed in a liquid storage container into which a bubbling gas is introduced, and a temperature difference between the self-heating sensor probe and the temperature measurement sensor probe. And a bubbling counter for counting the number of bubbling periods of the bubbling gas based on the temperature difference between the two sensor probes. 2. A sensor for detecting a liquid level of a liquid stored in a liquid storage container into which a bubbling gas is introduced, the sensor probe for self-heating disposed in the liquid storage container and a temperature. A sensor probe for measurement, a temperature difference detecting means for detecting a temperature difference between the sensor probe for self-heating and the sensor probe for temperature measurement, and a liquid level of the liquid based on a temperature difference between the two sensor probes. A sensor comprising: a liquid level determining means for determining; and a bubbling counting means for counting the number of bubbling periods of the bubbling gas based on a temperature difference between the two sensor probes. 3. The pulse generating means for generating a pulse signal when the temperature difference between the self-heating probe sensor and the temperature measuring probe sensor decreases by a predetermined amount, and the bubbling counting means generates the pulse signal. 3. The sensor according to claim 1, further comprising a pulse counter for counting the number of pulses obtained. 4. The sensor according to claim 1, further comprising display means for displaying the number of times of said bubbling period counted by said bubbling counting means. 5. The probe sensor group comprising the self-heating probe sensor and the temperature measurement probe sensor has a plurality of sets, and the tip positions of the probe sensor groups in each set are different. A sensor according to claim 1. 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 storage container comprising: a temperature difference detection unit that detects a temperature difference between the sensor probe and a sensor probe; and a bubbling counting unit that counts the number of bubbling periods of the bubbling gas based on the temperature difference between the two sensor probes. 7. The liquid storage container according to claim 6, further comprising a heater for heating the liquid stored in the container main body, and a temperature sensor for detecting a temperature of the liquid in the container main body. 8. The liquid storage 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 storage container into which bubbling gas is introduced, a temperature difference between these sensor probes is detected, and the temperature difference is detected based on the temperature difference. A bubbling detection method for counting the number of bubbling periods of bubbling gas.