JP2003173896A - Abnormal discharge detection device, abnormal discharge detection method, and plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply, quickly, and precisely detect an abnormal discharge of a plasma treatment device. <P>SOLUTION: A first filter 3 transmitting only the signal of relatively low frequency side, and a second filter 4 transmitting only the signal of relatively high frequency side are mounted to a treating means of the abnormal discharge detection device of the plasma treatment device generating plasma, which is at least equipped with an ultrasonic sensor 1 and the treatment means detecting abnormal discharge by treating an ultrasonic wave detection output of the ultrasonic wave sensor 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an abnormal discharge detection device,
TECHNICAL FIELD The present invention relates to an abnormal discharge detection method and a plasma processing apparatus, and particularly, an abnormal plasma discharge that is undesirably generated when a high voltage or a high frequency voltage from a high frequency power source is applied is easily, quickly, and accurately produced. The present invention relates to an abnormal discharge detection device, an abnormal discharge detection method, and a plasma processing device which are characterized by a configuration for detection.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductor manufacturing technology, C
A plasma treatment method of treating a substrate to be treated with plasma discharge is widely used for VD (chemical vapor deposition), ashing, etching, sputtering, surface treatment, and the like.

In such a plasma processing process, abnormal discharge of plasma generated in the plasma processing apparatus causes dust generation, damage to the surface of the substrate to be processed, substrate contamination, dielectric breakdown of electronic elements provided on the substrate, etc. Therefore, in order to deal with such a problem, it is required to accurately detect the occurrence of abnormal discharge.

At present, various studies have been conducted to meet such demands, and a change in emission intensity of plasma, a change in voltage / current of a power source, a change in plasma impedance, or a change in harmonics is detected. By doing so, it has been attempted to detect abnormal discharge.

However, in the method of monitoring the change in plasma emission intensity, since the plasma generating portion of many plasma processing apparatuses is covered with a shield, it is necessary to attach an optical fiber to detect the change in plasma emission due to abnormal discharge. It requires considerable modification, and even if it is attached, there is a problem that the plasma characteristics change.

Further, even in the case of an apparatus in which a viewing window is open in the process chamber, the entire plasma emission cannot be viewed, and it is difficult to reliably detect abnormal discharge in specifying the position.

Further, in the case of the abnormal discharge detection method of monitoring the change of the voltage or current of the RF power source or the change of the plasma impedance, the occurrence of the abnormal discharge cannot be detected completely, and in addition, the abnormal discharge causes Since it occurs in other places, even if abnormal discharge can be detected completely,
Its position cannot be specified.

Further, although the method of detecting the change in the generation state of harmonics can detect the occurrence of abnormal discharge, it cannot specify the position of abnormal discharge.

Therefore, when the abnormal discharge of plasma occurs, the inventor of the present invention discharges ultrasonic waves (AE: Accous).
The AE sensor is attached to the outer wall of the plasma processing apparatus to detect the AE generated by the abnormal discharge by utilizing the fact that the generated AE propagates through the outer wall of the plasma processing apparatus. Has been proposed (see Japanese Patent Application No. 2000-89840, if necessary).

According to this detection method, since the AE sensor is simply attached to the outer wall of the plasma processing apparatus, the plasma processing apparatus does not need to be significantly modified, and a plurality of A
By mounting the E sensor, it is possible to specify the position of the abnormal discharge from the time difference between the AE detections of the AE sensors.

[0011]

However, the AE sensor attached to the plasma processing apparatus is provided with an A sensor from a mechanically movable part such as a wafer transfer in a load lock chamber during plasma discharge.
Since the E wave is also detected, there is a problem that the AE wave due to abnormal discharge and the AE wave due to mechanical vibration cannot be distinguished as they are.

Then, the present inventor again made a diligent search for the difference between the AE wave caused by the abnormal discharge and the AE wave caused by the mechanical vibration, and found that there was a difference in the frequency distribution. This will be described with reference to FIG.

9 (a) to 10 (c). FIG. 9 (a) is an AE waveform due to an abnormal plasma discharge that is intentionally generated, and FIG. 9 (b) is shown in FIG. 9 (a). AE
10A to 10C are Fourier spectra obtained by spectrally analyzing the waves, and FIGS. 10A to 10C are also Fourier spectra of AE waves due to abnormal plasma discharge intentionally generated as in the case of FIG. In addition, in the Fourier spectrum shown in FIG. 10A, although the relative intensity is small, the spectrum actually exists near 5 kHz and near 200 kHz.

11 (a) to 12 (c). FIG. 11 (a) shows A due to mechanical vibration intentionally generated.
11 (b) is a Fourier spectrum of the AE wave of FIG. 11 (a), and FIGS. 12 (a) to 12 (c) are intentionally generated as in the case of FIG. It is the Fourier spectrum of the AE wave by the mechanical vibration caused.

Comparing the above Fourier spectra, it is understood that the AE wave due to mechanical vibration has a relatively low frequency component, and the AE wave in the abnormal plasma discharge has a relatively high frequency component.

Then, as a result of earnest study, spectral components near 5 kHz in these Fourier spectra,
Focusing on the spectrum component near 200 kHz, it was found that abnormal discharge can be determined by obtaining the ratio of the amplitude of the spectrum component near 5 kHz to the amplitude of the spectrum component near 200 kHz.

However, there is a problem that such spectrum analysis takes some time, and the determination of abnormal discharge is delayed, and it is required to perform such abnormal discharge determination as fast as possible in real time. There is.

Therefore, an object of the present invention is to detect abnormal discharge of plasma in a plasma processing apparatus more easily, at high speed and with high accuracy.

[0019]

FIG. 1 is a block diagram showing the principle of the present invention. The means for solving the problems in the present invention will be described with reference to FIG. Reference numerals 5-6 and 9 are a buffer amplifier, an amplifier, and a computer processing unit, respectively. See FIG. 1 (1) The present invention includes at least an ultrasonic sensor 1 attached to a plasma processing apparatus that generates plasma, and a processing unit that processes an ultrasonic detection output of the ultrasonic sensor 1 to detect abnormal discharge. In the abnormal discharge detection device of the plasma processing apparatus, the processing means has the first filter 3 that transmits only the signal on the relatively low frequency side and the second filter that transmits only the signal on the relatively high frequency side. 4 and at least two filters are provided.

As described above, by using the first filter 3 that transmits only the signal on the relatively low frequency side and the second filter 4 that transmits only the signal on the relatively high frequency side, the time Such spectrum analysis becomes unnecessary and the device configuration is simplified. It should be noted that three or more filters may be provided, and the optimum two may be selected according to the configuration of the plasma processing apparatus or the plasma processing conditions.

(2) Further, in the present invention according to the above (1), the first filter 3 for transmitting only a signal on a relatively low frequency side is a bandpass filter having a relatively low frequency transmission band. The second filter 4 that transmits only the signal on the relatively high frequency side is a bandpass filter having a relatively high frequency transmission band.

In this case, the first filter 3 may be a low-pass filter having a low-frequency transmission band, but a band-pass filter having a relatively low-frequency transmission band is preferable for selecting a specific frequency. The second filter 4 may be a high-pass filter having a high-frequency transmission band, but a band-pass filter having a relatively high-frequency transmission band is preferable in order to select a specific frequency.

(3) Further, the present invention provides an abnormal discharge detection method for a plasma processing apparatus, which processes an ultrasonic detection output of an ultrasonic sensor 1 attached to a plasma processing apparatus for generating plasma to detect abnormal discharge, A part of the ultrasonic detection output is detected through the first filter 3 that transmits only the signal on the relatively low frequency side, and a part of the ultrasonic detection output is detected on the signal on the relatively high frequency side. Second transparent
Is detected through the filter 4, and both detection outputs are compared, and the generation of ultrasonic waves due to abnormal discharge is determined from the ratio.

(4) Further, in the present invention according to the above (3), the first filter 3 which transmits only a signal on a relatively low frequency side is a bandpass filter having a transmission band of 4 to 6 kHz, and The second filter 4 that transmits only the signal on the high frequency side is a bandpass filter having a transmission band of 180 to 220 kHz.

Thus, the detection output on the low frequency side is 4
By using the frequency band of ˜6 kHz and the frequency band of 180 to 220 kHz as the detection output on the high frequency side, ultrasonic waves due to mechanical vibration and ultrasonic waves due to abnormal plasma discharge can be clearly distinguished.

(5) Further, in the present invention according to the above (3) or (4), when the detection outputs from the first filter 3 and the second filter 4 are amplified, the amplified detection outputs are detected. Each amplification factor is set so that the maximum value of the amplitude becomes the maximum input range of the analog-digital converter 8 provided in the subsequent stage.

In this way, by amplifying each detection output so as to reach the maximum input range of the analog-digital converter 8, each detection output having different relative intensities is stably A / D.
It can be converted, which enables highly accurate determination.

(6) Further, in the present invention according to any one of the above (3) to (5), a part of the ultrasonic wave detection output of the ultrasonic sensor 1 is detected without passing through a filter, and this detection output is obtained. It is characterized in that the generation of ultrasonic waves due to the above-mentioned abnormal discharge is determined only when the value is equal to or greater than a predetermined reference value.

As described above, by using the signal output that does not pass through the filter, useless detection operation can be eliminated, and when an ultrasonic wave is actually generated, it is possible to make a quick determination.

(7) Further, in the present invention according to any one of (3) to (6) above, the ultrasonic sensor 1 is relatively sensitive to a signal on a relatively low frequency side, and Using the ultrasonic sensor 1 having a high sensitivity to a signal on the high frequency side, the output from the ultrasonic sensor 1 having a high sensitivity to a signal on the relatively low frequency side is detected via the first filter 3. At the same time, the output from the ultrasonic sensor 1 having a high sensitivity to the signal on the relatively high frequency side is detected through the second filter 4.

As described above, by using different ultrasonic sensors 1 which are respectively highly sensitive to at least two frequencies to be detected, it is possible to discriminate abnormal discharge with higher accuracy.

(8) Further, in the present invention according to any one of the above (3) to (6), a plurality of ultrasonic sensors 1 are attached to the plasma processing apparatus, and at least one of the plurality of ultrasonic sensors 1 is attached. It is characterized in that the generation of ultrasonic waves due to abnormal discharge is determined using the ultrasonic wave detection output of one ultrasonic wave sensor 1.

As described above, by mounting a plurality of ultrasonic sensors 1, the position of the ultrasonic wave generation source can be specified as in the conventional case, and the detection output of at least one of the ultrasonic sensors 1 can be determined. However, when only one ultrasonic sensor 1 is used, it is desirable to use the output of the ultrasonic sensor 1 that outputs the maximum detection output,
As a result, more accurate determination can be performed. Alternatively, by using the detection outputs of the plurality of ultrasonic sensors 1 to individually determine abnormal discharge and further comprehensively determining the determination results, it is possible to perform determination with higher accuracy.

(9) Further, the present invention is characterized in that the plasma processing apparatus is provided with the abnormal discharge detection apparatus described in (1) or (2) above.

As described above, by equipping the plasma processing apparatus with the abnormal discharge detecting device in advance, the ultrasonic sensor 1 or the filter having the characteristics corresponding to the abnormal discharge form peculiar to each plasma processing apparatus is selected at the product stage. Therefore, it is possible to reduce the work load for initial adjustment and the like.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will now be described with reference to FIGS. See FIG. 2. FIG. 2 is a conceptual configuration diagram of a plasma processing apparatus including an abnormal discharge detection apparatus to which the present invention is applied.
A parallel plate type electrode composed of a lower electrode 14 also serving as a sample stage and an upper electrode 15 facing the lower electrode 14 is housed in a chamber 11 provided with 2 and an exhaust port 13.
The wafer 16 to be processed is placed on the wafer 4.

The lower electrode 14 is connected to the RF power source 18 via the blocking capacitor 17, while the upper electrode 15 is grounded, which constitutes the basic structure of the plasma processing apparatus. The AE sensor 19 is attached to the outer wall of the chamber 11 of such a plasma processing apparatus.

See FIG. 3. FIG. 3 is a conceptual configuration diagram of the abnormal discharge detection device of the present invention, in which the outputs from the AE sensor 19 and the AE sensor 19 mounted on the outer wall of the chamber 11 of the above-described plasma processing apparatus are appropriate. Of the output of the buffer amplifier 21 and the output of the buffer amplifier 21, only the frequency component near 5 kHz has a transmission center frequency of 5 kHz, and the 5 kHz band pass filter 22 has the transmission center frequency of only the frequency component near 200 kHz. 200 kHz 2
00 kHz band pass filter 23, buffer amplifier 2
The amplifiers 24 to 26 and A for amplifying the output of 1 and the output of the 5 kHz band pass filter 22 and the output of the 200 kHz band pass filter 23 to the maximum input range of the A / D conversion unit 27 at the next stage, respectively. It is configured by a computer unit 28 that processes the output of the / D conversion unit 27.

In this case, since the AE sensor 19 is a 200 kHz resonance type AE sensor which can obtain a certain degree of sensitivity in the main frequency band of 2 kHz to 250 kHz of the AE wave generated by the abnormal discharge, it is used here. The sensitivity frequency characteristics of the 200 kHz resonance type AE sensor will be described with reference to FIG.

See FIG. 4 (a). FIG. 4 (a) is a sensitivity frequency characteristic in a longitudinal wave waveform in a high frequency region of 100 kHz or more, which is a reference value (0 dB).
Is 1 V / m / s (voltage per oscillating particle velocity is 1 V), and has a relatively large sensitivity at 200 kHz.

See FIG. 4B. FIG. 4B shows the sensitivity frequency characteristic in the low frequency region of 60 kHz or less, and the reference value (0 dB) is 38.5 mV.
/ M / s ² (voltage per acceleration is 38.5 mV), and the output of the AE sensor is 26 dB (20
Amplified and shown.

In this low frequency region, the phase difference of the elastic waves propagating inside the piezoelectric vibrator forming the AE sensor is small, the output voltage of the AE sensor is small, and the output voltage of the AE sensor operating is large. Therefore, the characteristics are obtained when operated as an acceleration sensor.

5 (a) and 5 (b). FIG. 5 (a) is a frequency characteristic diagram of the 5 kHz bandpass filter 22 and has a transmission peak at 5 kHz.
Further, FIG. 5B is a frequency characteristic diagram of the 200 kHz bandpass filter 23, which has a sharp transmission peak at 200 kHz.

In the abnormal discharge detection device having such a configuration, the AE signal detected by the AE sensor 19 is passed through the buffer amplifier 21, and then one is amplified by the amplifier 24 without passing any filter, and the A / D The conversion unit 27 converts it into a digital signal and takes it into the computer unit 28.
The outputs from the 5 kHz bandpass filter 22 and the 200 kHz bandpass filter 23 are amplified by the amplifiers 25 and 26, and then converted into a digital signal by the A / D conversion section 27 and taken into the computer section 28.

In this case, the amplification factors of the amplifiers 24 to 26 are set to, for example, 1 times the amplification factor of the amplifier 24 so that the maximum value of the output of the amplifier becomes the maximum input range of the A / D converter 27. The amplification factor of 25 is set to 8 times, and the amplification factor of the amplifier 26 is set to 4 times.

Further, in the computer section 28, the maximum amplitude due to background noise when AE is not occurring is measured in advance for each processed signal,
The difference between the maximum amplitude measured in advance and the amplitude of the detection signal is
When it becomes larger than a threshold value set corresponding to the magnitude of abnormal discharge to be detected in advance, detection of a signal through the 5 kHz band pass filter 22 and the 200 kHz band pass filter 23 is started. For example, full scale is 2V
In that case, 0.1 V is set as the threshold value.

Then, after that, when the amplitude becomes smaller than the threshold value within a preset time range, 5 kH
The detection of the signal through the z bandpass filter 22 and the 200 kHz bandpass filter 23 is completed. As the preset time, at least one cycle (200 μs at 5 kHz) is required, but since the periodicity of the AE wave may not be good in some cases, it is set to, for example, 5 cycles (= 1 ms).

Next, by the configuration shown in FIGS. 2 and 3, A
The result of detecting the E wave is 5 for the amplitude of 200 kHz.
The ratio of the amplitude in kHz is shown in FIG. See FIG. 6. This figure shows the AE wave shown in FIGS.
The outputs detected through the Hz bandpass filter 22 and the 200 kHz bandpass filter 23, and FIGS. 9 to 12 are spectra obtained by separately analyzing the outputs that do not pass through the bandpass filter.

Further, in FIG. 6, the output through the 20 kHz band pass filter and the output through the 80 kHz band pass filter is also shown as a ratio to the amplitude of 200 kHz in order to examine the characteristics in other frequency bands together. In this case, the amplification factor of the output of the amplifier through the bandpass filter is 4 times in the case of the 20 kHz bandpass filter and 2 times in the case of the 80 kHz bandpass filter.

As shown in FIG. 6, AE due to abnormal plasma discharge
It is understood that the wave has a smaller amplitude ratio of the output through the 5 kHz bandpass filter 22 as compared with the AE wave due to mechanical vibration.

Therefore, 5 k relative to the maximum amplitude of the AE wave signal passed through the 200 kHz band pass filter 23.
By determining the ratio of the maximum amplitude of the AE wave signal that has passed through the Hz band pass filter 22, it is possible to determine the abnormal discharge of plasma. Although the threshold for determination is not absolute, in the case of FIG. 6, the value in abnormal discharge with the largest amplitude ratio is 0.696 (≈0.7), and the lowest mechanical vibration. Since the value is 2.041 (≈2), the threshold may be set in the range of 0.7 to 2, for example, 1.

Further, the abnormal discharge 2 corresponding to FIG.
Can be determined to be an abnormal discharge by the above determination, but it is understood that the maximum amplitude ratio in the case without a filter and the maximum amplitude ratio through an 80 kHz bandpass filter are clearly different from other abnormal discharges. This is considered to reflect that the form itself of abnormal discharge is different.

That is, the 200 kHz bandpass filter 2
If the ratio of the maximum amplitude of the unfiltered signal to the maximum amplitude of the signal passed through No. 3 or the maximum amplitude of the signal passed through the 80 kHz bandpass filter is obtained, it is possible to determine the difference in the form of abnormal discharge.

Next, the second embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 shows the AE of the second embodiment.
It is a conceptual block diagram of the plasma processing apparatus which attached the sensor, and 5 is attached to the outer wall of the chamber 11 of the plasma processing apparatus.
Low frequency AE sensors 31 and 200 with high sensitivity in the vicinity of kHz
A high frequency AE sensor 32 having a high sensitivity in the vicinity of kHz is attached.

In the second embodiment, since a separate sensor having a high sensitivity in the required frequency band is used, it is possible to determine abnormal discharge with higher accuracy.

Next, a third embodiment of the present invention will be described with reference to FIG. 8. FIG. 8 is a conceptual view for explaining the mounting structure of the AE sensor of the third embodiment of the present invention. It is a block diagram, and three AE sensors 33 to 36 are attached to the outer wall of the plasma processing apparatus and one to the top surface.

In the third embodiment, as already proposed, the discharge position is specified from the time difference between the detection outputs of the four AE sensors 33 to 36 (if necessary, the above-mentioned Japanese Patent Application No. 2000-89840), 4
Among the outputs of the individual AE sensors 33 to 36, the output of the AE sensor that outputs the maximum output is used to determine the above-mentioned abnormal discharge.

In the third embodiment, not only the occurrence of abnormal discharge but also the position of occurrence can be specified.
In addition, since the maximum output of the outputs of the AE sensors 33 to 36, that is, the AE signal closest to the position where the abnormal discharge occurs, the AE signal with less attenuation can be used, the determination accuracy can be further improved. It will be possible.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the respective embodiments, and various modifications can be made. For example, in each of the above-described embodiments, a parallel plate electrode type plasma processing apparatus is described as an example of the plasma processing apparatus, but the plasma processing apparatus is configured in such a parallel plate electrode type plasma processing apparatus. The present invention is not limited to this, but is applied to plasma processing apparatuses of various structures in which abnormal discharge is expected to occur.

In each of the above embodiments, 5
Although the detection output in the vicinity of kHz and the detection output in the vicinity of 200 kHz are compared, such a frequency is not absolute, and if the configuration of the plasma processing apparatus changes greatly in the future, such a unique frequency will be generated. May change, and in that case, a combination of frequencies may be selected according to the change.

Further, in each of the above-mentioned embodiments, the bandpass filter is used to take out the output of the predetermined frequency, but it is not always necessary to use the bandpass filter, and for example, the output on the low frequency side is detected. A low pass filter may be used for this purpose, and a high pass filter may be used for detecting the output on the high frequency side.

In the above second embodiment, two AE sensors having different frequency sensitivity characteristics are used, and two AE sensor elements having different frequency sensitivity characteristics are integrally mounted to form a composite structure. It is also possible to use a single composite AE sensor.

Further, in the third embodiment, four AE sensors are used, but three AE sensors may be used, or five AE sensors including the lower bottom surface of the chamber are attached. In any case, the discharge position can be specified.

Further, also in the third embodiment described above, as each AE sensor of the plurality of AE sensors, a composite AE sensor in which two AE sensor elements having different frequency sensitivity characteristics are integrally mounted and compounded. May be used.

In the third embodiment, the abnormal discharge is determined by using the output of the AE sensor that outputs the maximum output among the outputs of the four AE sensors. It is also possible to determine the abnormal discharge by using the output of the AE sensor.

Further, out of the outputs of the four AE sensors, a plurality of, for example, the outputs of two AE sensors may be used to determine the abnormal discharge, and the individual determination results are comprehensively determined. This makes it possible to determine the abnormal discharge with higher accuracy.

Further, in the first embodiment described above, the number of filters constituting the abnormal discharge detection device is two, but as described with reference to FIG. 6, another filter such as an 80 kHz bandpass filter is used. It is also possible to use a filter having frequency sensitivity characteristics together, whereby
It is also possible to detect the difference in the form of abnormal discharge.

[0068]

According to the present invention, since the AE signal of the frequency to be detected is acquired by using a plurality of filters without spectral analysis, abnormal plasma discharge can be easily, quickly and accurately performed. It becomes possible to make a good judgment, and by feeding back the result to the manufacturing conditions or the design of the plasma processing apparatus, it is largely contributing to the improvement of the throughput of the plasma processing step and the reliability of the plasma processing apparatus.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a principle configuration of the present invention.

FIG. 2 is a conceptual configuration diagram of a plasma processing apparatus including an abnormal discharge detection device to which the present invention is applied.

FIG. 3 is a conceptual configuration diagram of an abnormal discharge detection device used in the embodiment of the present invention.

FIG. 4 is an explanatory diagram of sensitivity frequency characteristics of a 200 kHz resonance type AE sensor.

FIG. 5 is a frequency characteristic diagram of a bandpass filter used in the embodiment of the present invention.

FIG. 6 is an explanatory diagram of measurement results according to the first embodiment of the present invention.

FIG. 7 is a conceptual configuration diagram of a second embodiment of the present invention.

FIG. 8 is a conceptual configuration diagram of a third embodiment of the present invention.

FIG. 9: A due to abnormal plasma discharge intentionally generated
It is explanatory drawing of E wave.

FIG. 10 is a Fourier spectrum of an AE wave due to another plasma abnormal discharge intentionally generated.

FIG. 11 is an explanatory diagram of an AE wave due to mechanical vibration intentionally generated.

FIG. 12 AE due to other mechanical vibration intentionally generated
It is the Fourier spectrum of the wave.

[Explanation of symbols]

1 Ultrasonic sensor 2 buffer amplifier 3 First filter 4 Second filter 5 amplifier 6 amplifier 7 amplifier 8 analog-digital converter 9 Computer processing unit 11 chambers 12 gas inlet 13 Exhaust port 14 Lower electrode 15 Upper electrode 16 wafers 17 Blocking capacitor 18 RF power supply 19 AE sensor 21 Buffer amplifier 22 5kHz bandpass filter 23 200kHz bandpass filter 24 amplifiers 25 amps 26 amplifiers 27 A / D converter 28 Computer Department 31 Low frequency AE sensor 32 high frequency AE sensor 33 AE sensor 34 AE sensor 35 AE sensor 36 AE sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masayoshi Takeshita             358-3 Stock Association, Toriko Nishihara Village, Aso District, Kumamoto Prefecture             Company Tokyo Cathode Research Institute Kyushu Office F-term (reference) 5F004 BA04 BB17                 5F045 AA08 BB20 DP03 DQ10 GB08

Claims (9)

[Claims] 1. An abnormality of a plasma processing apparatus comprising at least an ultrasonic sensor attached to a plasma processing apparatus for generating plasma, and processing means for processing an ultrasonic detection output of the ultrasonic sensor to detect abnormal discharge. In the discharge detection device, the processing means includes at least a first filter that transmits only a signal on a relatively low frequency side and a second filter that transmits only a signal on a relatively high frequency side.
An abnormal discharge detection device for a plasma processing apparatus, which is equipped with two filters. 2. The first filter, which transmits only the signal on the relatively low frequency side, is a bandpass filter in the transmission band of the relatively low frequency, and transmits only the signal on the relatively high frequency side. 2. The abnormal discharge detection device of the plasma processing apparatus according to claim 1, wherein the second filter to be transmitted is a bandpass filter having a relatively high frequency transmission band. 3. A method for detecting abnormal discharge in a plasma processing apparatus, which detects an abnormal discharge by processing an ultrasonic detection output of an ultrasonic sensor attached to a plasma processing apparatus for generating plasma, wherein a part of the ultrasonic detection output is used. Is detected through a first filter that transmits only a signal on the relatively low frequency side, and a second filter that transmits only a signal on the relatively high frequency side to a part of the ultrasonic detection output is detected. A method for detecting abnormal discharge in a plasma processing apparatus, characterized in that the generation of ultrasonic waves due to abnormal discharge is determined from the ratio of the detected outputs of the two, and the detection outputs of the two are compared. 4. The first filter for transmitting only the signal on the relatively low frequency side is a bandpass filter having a transmission band of 4 to 6 kHz, and the first filter for transmitting only the signal on the relatively high frequency side. The second filter has a transmission band of 180 to 2
The abnormal discharge detection method of the plasma processing apparatus according to claim 3, wherein the method is a bandpass filter of 20 kHz. 5. When amplifying the detection outputs from the first filter and the second filter, the maximum value of the amplitude of each amplified detection output is the maximum input range of the analog-digital converter provided in the subsequent stage. 5. The abnormal discharge detection method for a plasma processing apparatus according to claim 3, wherein each amplification factor is set so that 6. Generation of ultrasonic waves due to the abnormal discharge only when a part of ultrasonic detection output of the ultrasonic sensor is detected without passing through a filter, and only when the detected output is equal to or more than a predetermined reference value. The abnormal discharge detection method of the plasma processing apparatus according to claim 3, wherein the abnormal discharge detection method is performed. 7. As the ultrasonic sensor, an ultrasonic sensor having a high sensitivity to a signal of a relatively low frequency side and an ultrasonic sensor having a high sensitivity to a signal of a relatively high frequency side are used, The output from the ultrasonic sensor having a high sensitivity to the signal on the low frequency side is detected through the first filter, and the output from the ultrasonic sensor having a high sensitivity to the signal on the relatively high frequency side is detected. The abnormal discharge detection method for a plasma processing apparatus according to claim 3, wherein the abnormal discharge detection is performed via the second filter. 8. A plurality of the ultrasonic sensors are attached to the plasma processing apparatus, and the ultrasonic detection output of at least one of the ultrasonic sensors is used to detect the generation of ultrasonic waves due to abnormal discharge. The abnormal discharge detection method for a plasma processing apparatus according to claim 3, wherein the determination is performed. 9. A plasma processing apparatus comprising the abnormal discharge detection device according to claim 1. Description: