JP3304430B2 - Gas supply monitoring device and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for monitoring gas supply, and more particularly to an apparatus for monitoring the supply of process gas to a processing apparatus for processing semiconductor wafers.

In the processing of semiconductor wafers, it is important that a predetermined amount of process gas is normally supplied in order to improve product yield.

For this reason, a process gas supply device for supplying a process gas to a processing device is provided with a device for monitoring a gas supply state.

It is desirable that the gas supply monitoring device be capable of detecting an abnormality as early as possible. This is because, if the detection is delayed, the product yield will be reduced accordingly.

[0005]

2. Description of the Related Art FIG. 7 shows a conventional gas supply monitoring device.
In the figure, reference numeral 1 denotes a processing apparatus for processing a semiconductor wafer, and 2 denotes a process gas source.

Reference numeral 3 denotes a fixed gas supply device, which is provided in the middle of a pipe 4 from the process gas source 2 to the processing device 1, and has a mass flow controller (MFC) 5, air actuated valves 6, 7, solenoid valves 8, This is a configuration including a compressed air source 9 and the like.

The MF is set according to a setting signal from the CPU 10.
C5 is set so that the flow rate becomes a predetermined value.

The solenoid valve 8 is opened or closed according to an on-off valve signal from the CPU 10. When the solenoid valve 8 is opened, the pneumatic valves 6 and 7 are opened by the compressed air from the compressed air source 9.

When the valves 6 and 7 are opened, the MFC 5
Is supplied to the processing apparatus 1 at a flow rate determined by the above.

Reference numeral 11 denotes a Pirani vacuum gauge, which is provided inside the processing apparatus 1.

When the fixed gas supply device 3 fails and the flow rate of the process gas supplied into the processing device 1 becomes abnormal, the degree of vacuum in the processing device 1 slightly changes, and the Pirani vacuum gauge 11 recognizes this fact. Upon detection, the alarm device 12 operates to notify the abnormality.

That is, the conventional apparatus is configured to issue an alarm when the Pirani vacuum gauge 11 provided inside the processing apparatus 1 detects an abnormality in the degree of vacuum.

[0013]

The Pirani vacuum gauge 11 detects an abnormality because an abnormality occurs in the quantitative gas supply device 3,
As a result, the flow rate of the gas sent out to the pipe 4 changes, the flow rate of the gas supplied into the processing apparatus 1 changes, and this influence gradually spreads into the processing apparatus 1 and the degree of vacuum in the processing apparatus 1 changes. Then, the time reaches the Pirani vacuum gauge 11.

For this reason, as shown in FIG. 8, the detection of the abnormality is delayed by a considerable time T ₁ from the time when the abnormality has occurred in the fixed gas supply device 3.

As a result, even if appropriate measures are taken immediately after the abnormality is detected, the wafer processed immediately before the abnormality is detected will be defective, and the product yield will be reduced.

Therefore, the present invention provides a fixed gas supply device with A
To provide a gas supply monitoring device which is provided with an E (Acoustic Emission) sensor to directly monitor the gas flow rate and detect that the fixed gas supply device has become abnormal, thereby realizing early detection of the abnormality. With the goal.

[0017]

FIG. 1 shows the principle configuration of a gas supply monitoring device 20 and method according to the present invention.

In the figure, parts corresponding to those shown in FIG. 7 are denoted by the same reference numerals.

Reference numeral 21 denotes an AE (Acoustic Emission) sensor which is attached to the fixed gas supply device 3. The AE sensor 21 outputs a voltage waveform (AE signal) corresponding to the operation state of the device 3.

Reference numeral 22 denotes an abnormality detecting means, and the AE sensor 2
1 is input, and based on the output of the AE sensor 21, it is detected that the operation of the fixed gas supply device 3 has become abnormal.

[0021]

An AE sensor is provided in the fixed gas supply device,
The configuration for detecting an operation abnormality based on the output of the AE sensor 21 operates so that this is detected when the operation of the fixed gas supply device 3 becomes abnormal.

[0022]

FIG. 2 shows a gas supply monitoring device 30 according to an embodiment of the present invention.

In the figure, parts corresponding to those shown in FIGS. 1 and 7 are denoted by the same reference numerals.

Reference numerals 21 _-1 , 21 _-2 , 21 _-3 , and 21 _{-4 denote} AE sensors, which are attached to the air-operated valve 6, the MFC 5, the air-operated valve 7, and the solenoid valve 8, respectively.

The AE sensors 21 _{-1 to} 21 _-4 have a structure in which piezoelectric ceramics are incorporated. The AE sensors 21 _{-1 to} 21 _-4 are operated by the valves 6, 7, 8 and the MFC 5, and by the gas flow in the valves 6, 7 and the MFC 5. The generated vibration is applied as mechanical stress to the piezoelectric ceramics, causing dielectric polarization in the piezoelectric ceramics and generating an electric field. For example, when the valve 6 is opened and the process gas flows, the AE sensor _21-1
Outputs an AE signal shown in FIG. 3A which is a voltage signal.

In the figure, reference numeral 31 denotes an AE signal waveform due to the valve opening operation, and subsequent numeral 32 denotes an AE signal waveform due to the flow of the process gas. The voltage amplitude is A ₁ > A ₂ .

Further, when the process gas flows through the MFC5 is AE sensor 21 _-2, and FIG. 3 (B) or (C)
AE signal waveforms 33 and 34 shown in FIG.

FIG. 3B shows that the flow rate of the process gas is Q _11.
FIG. 3C shows the case where the flow rate is Q ₂ l / min, which is larger than Q ₁ . The voltage amplitude is A ₄ > A ₃ .

As can be seen from the above, the voltage amplitude is substantially proportional to the gas flow.

When an abnormality occurs in the valves 6 and 7 or the MFC 5 and the flow rate of gas flowing therethrough changes, the AE sensors 21 _-1 and 2-1
1 _-3, the AE signal waveform 21 _-2 changed.

FIG. 3D shows, for example, that the valve 6 is set at time t _8.
In abnormality occurs, when the decreased flow rate of the process gas flowing through the valve 6, which is AE signal waveform of the AE sensor 21 _-1.

The AE signal waveform 35 is not delayed from the time t ₁ at which the valve 6 has failed, and is at the same time t 1.
It changes from ₁ to an AE signal waveform 36. The voltage amplitude is A
₆ <a A _5.

[0033] FIG. 3 (E) for example, the MFC5, time t error occurs in _2, an AE signal waveform of the AE sensor 21 _-2 when reduced flow rate of the process gas flowing in MFC5.

The AE signal waveform 37 changes to the AE signal waveform 38 from the same time t ₂ without being delayed from the time t ₂ at which the abnormality occurred in the MFC 5. The voltage amplitude is A ₈ <A ₇ .

In FIG. 2, reference numeral 40 denotes an AE measuring device.
Is converted to numerical data of “0” and “1”.

Reference numeral 41 denotes a microcomputer,
It comprises a U42, an entrance output unit 43, and a memory 44, evaluates data supplied from the AE measuring device 40, and detects an abnormality in the operation of the fixed gas supply device 3.

The memory 44 stores master data, which is an evaluation reference value of each evaluation parameter described later, and the processing device 1.
Are stored in advance. Note that the master data is different for each processing recipe.

The AE measuring device 40 and the microcomputer 41 constitute the abnormality detecting means 22.

Next, the operation of monitoring the gas supply will be described.

First, parameters for evaluating AE signals from the AE sensors 21 _{-1 to} 21 _-4 will be described.

As shown in FIG. 4, parameters to be evaluated with respect to the AE signal 50 are, for example, (i) ring-down count (ii) peak value (iii) rise time (iV) connection time. The ring-down count is performed by determining the threshold voltage Vs and counting the number of peaks. Next, the operation of the microcomputer 41 will be described with reference to FIG.

First, numerical data of an AE signal waveform from the AE measuring device 40 is fetched (ST1).

Next, the received AE signal numerical data is subjected to signal processing to remove noise (ST2).

Next, the evaluation parameters (ring-down count, peak value, rise time, connection time) shown in FIG. 4 are extracted from the captured AE signal numerical data (ST3).

Further, the master data corresponding to the processing recipe currently performed by the processing apparatus 1 is fetched from the memory 44 (ST4).

Next, the evaluation parameters extracted in step ST3 are compared with the master data fetched in step ST4 to determine whether or not each evaluation parameter is within the standard (ST5).

If the result of the determination is "YES", it is determined whether or not the wafer processing has been completed based on information from the processing apparatus 1 (ST6).

If the determination is "NO", the process returns to step ST1 and the above operation is performed again.

If the result of the determination is "YES", the operation of the microcomputer 41 ends.

Next, the case where the evaluation parameter is out of the standard will be described.

In this case, the result of the judgment in step ST5 is "NO".

At this time, the AE signal numerical data at this time is stored in the memory 44 (ST7).

Subsequently, an alarm signal is output (ST8).

This signal is sent to the display device 60 in FIG. 2, where an alarm is displayed.

An emergency stop signal is output (ST
9).

This signal is sent to the processing device 1 in FIG.
The processing device 1 stops the operation urgently.

Next, the relationship between the time when an abnormality occurs in the fixed gas supply device 3, the time when an alarm is displayed, and the time when an emergency stop is performed will be described with reference to FIG.

For example, assume that an abnormality has occurred in the valve 6 at time t ₁ .

[0059] AE signal waveform of the AE sensor 21 _-1, the valve 6
Becomes abnormal at the same time as the state indicated by reference numeral 35 to reference numeral 36. The microcomputer 41 immediately outputs an alarm signal and an emergency stop signal. Accordingly, without delay with respect to the time t _1, the alarm display is performed, and device 1 is urgently stopped.

That is, at a point in time before the atmosphere in the processing apparatus 1 becomes abnormal, an alarm is displayed and the apparatus 1 is stopped.

Therefore, the wafer being processed does not become defective, and the yield does not decrease.

Further, it is possible to take measures for the above-mentioned abnormality at an early stage.

[0063]

As described above, according to the first aspect of the present invention, the abnormality can be detected when the operation of the fixed gas supply means becomes abnormal by directly monitoring the gas flow rate. An abnormality can be detected before the influence caused by the abnormality in the fixed gas supply means reaches the processing apparatus.

According to the second aspect of the present invention, the processing apparatus is not affected before the influence of the malfunction of the fixed gas supply means on the processing apparatus, that is, before the gas atmosphere in the processing apparatus becomes abnormal. Operation can be stopped. As a result, the product being processed does not become a defective product, and a decrease in product yield can be prevented.

According to the third aspect of the present invention, the alarm is issued before the influence of the abnormal gas supply means becomes abnormal, that is, before the gas atmosphere in the processing apparatus becomes abnormal. Can be displayed. As a result, the operator can take measures for the abnormal situation at an early stage.

According to the fourth aspect of the present invention, when the operation of the quantitative gas supply means becomes abnormal by directly monitoring the gas flow rate, the abnormality can be detected, and the quantitative gas supply means becomes abnormal. It is possible to detect an abnormality before the influence due to the influence reaches the processing device.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of a gas supply monitoring device and method of the present invention.

FIG. 2 is a diagram showing one embodiment of a gas supply monitoring device of the present invention.

FIG. 3 is a diagram showing an AE signal waveform.

FIG. 4 is a diagram illustrating evaluation parameters for an AE signal.

FIG. 5 is a flowchart of the operation of the microcomputer in FIG. 2;

FIG. 6 is a diagram illustrating a temporal relationship among a time point when a valve abnormality occurs, a time point when an alarm is displayed, and an emergency stop time point.

FIG. 7 is a diagram showing a conventional gas supply monitoring device.

FIG. 8 is a diagram illustrating a delay in abnormality detection.

[Explanation of symbols]

2 process gas source 3 Quantitative gas supply device 4 pipe 5 a mass flow controller (MFC) 6, 7 air operated valve 8 solenoid valve 9 compressed air source 20 gas supply monitoring device 21,21 _-1, 21 _-4 AE sensor 22 abnormality detection means Reference Signs List 30 gas supply monitoring device 31-38 AE signal waveform 40 AE measuring device 41 microcomputer 42 CPU 43 input / output unit 44 memory 50 AE signal 60 display device

Claims (4)

(57) [Claims] 1. A gas supply device comprising a mass flow controller (5) and valves (6, 7, 8) and having a fixed gas supply means (3) for supplying a predetermined flow rate of gas to a processing device (1). The AE sensor (21 _-1 to 2-1) is provided in the fixed gas supply means (3) itself.
_21-4 ), an abnormality detecting means for extracting an evaluation parameter from a voltage signal output from the AE sensor, comparing the extracted parameter with master data, and detecting that the operation of the fixed gas supply means has become abnormal. A gas supply monitoring device comprising (22). 2. The operation abnormality detecting means detects that the operation of the quantitative gas supply means has become abnormal,
2. The gas supply monitoring device according to claim 1, wherein the operation of the processing device is stopped urgently. 3. The operation abnormality detection means detects that the operation of the quantitative gas supply means has become abnormal,
The gas supply monitoring device according to claim 1, wherein an alarm is displayed on the display means (60). 4. An evaluation parameter is extracted from an AE sensor (21 _{-1 to} 21 _-4 ) output voltage signal provided in a fixed gas supply means (3) itself for supplying a predetermined flow rate of gas to the processing device (1), A gas supply monitoring method, wherein the extracted evaluation parameters are compared with master data to detect that the operation of the quantitative gas supply means has become abnormal.