JPH1116889A - Method and device for detecting end point of plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a malfunction in detecting the end point of a plasma treatment in a semiconductor process and to always detect an optimum end point. SOLUTION: One copying operation is conducted to memorize a waveform which is made by converting the intensity of light emission in a certain wavelength of plasma light emission into an electric signal. First, only a certain wavelength previously designated is fetched by a spectroscope 1. Light fetched by the spectroscope 1 is output to a waveform memorizing circuit 6 via a photoelectric converter 2 and an amplifier 3. Meanwhile, the signal of the amplifier 3 is output to the waveform memorizing circuit 6 via an analog-to-digital converter 4 and an arithmetic circuit 5. In this manner, two signals before and after computation are input to the waveform memorizing circuit 6, and the waveform in which an end point is more easily judged is selected and is made a comparison base waveform. When a plasma treatment is conducted thereafter, the end of the plasma treatment is judged by comparing the comparison base waveform in the waveform memorizing circuit 6 with a signal obtained from light emission in the plasma treatment by a comparison circuit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing end point detecting method and an end point detecting apparatus using the method.

[0002]

2. Description of the Related Art Conventionally, an end point detecting method and apparatus used for plasma processing determine the end point of plasma processing with a circuit configuration as shown in FIG. The spectroscope 41 captures only the light of a predetermined wavelength from the emission of plasma when processing the material to be processed. Spectroscope 41
The light taken in is converted into an electric signal of the emission intensity of the designated wavelength via the photoelectric converter 42 and the amplifier 43 and output to the end point detection circuit 46. Further amplifier 43
Is converted into a digital signal by the analog-to-digital converter 44, and the signal processed by the arithmetic circuit 45 is output to the end point detection circuit 46. The end point detection circuit 46 receives two signals before and after the arithmetic processing. Signals for which the end point can be easily determined are selected in advance and the end point detection conditions are set. An end point detection circuit 46 based on the input signal
Determines that the plasma processing is completed when a preset end point detection condition is satisfied, and sends a processing stop signal to the CPU 4 of the apparatus.
Send to 7.

[0003]

However, in the above-mentioned conventional plasma processing end point detection method, when the processing conditions are the same as the material to be plasma processed and an abnormality is found due to a change in the state of the plasma processing chamber or the like. However, there is a problem in that if the preset end point detection condition of the plasma processing is met, the end point is detected as a normal plasma processing.

In addition, the conventional end point detection apparatus using the plasma end point detection method has a problem that the above-described abnormality cannot be detected and the processing is regarded as normal and the processing is continued. .

Therefore, the present invention is intended to provide a plasma processing apparatus which can be used even when the material to be processed and the plasma processing conditions are the same, and abnormalities due to changes in the state of the plasma processing chamber are observed.
It is an object of the present invention to provide an end point detection method that eliminates a malfunction such that an end point is detected as a normal plasma processing when a preset plasma processing end point detection condition is met, and always enables optimal end point detection. I do.

Another object of the present invention is to provide a plasma processing end point detecting apparatus which eliminates a malfunction caused by a conventional end point detecting apparatus using a conventional plasma end point detecting method by using the above method.

[0007]

According to a first aspect of the present invention, there is provided a plasma end point detecting method, in which a waveform shape of an emission intensity at a certain wavelength of plasma emission is stored, and the stored waveform shape and the shape of the waveform are determined. It is characterized in that the end point of the plasma processing is determined by always comparing.

According to the present invention, when the plasma processing material and the plasma processing conditions are the same, the detected emission intensity waveform at a certain wavelength of the plasma emission during the processing is stored, and the stored waveform is Since the end point is detected after the shape is compared with the shape, the optimum end point can always be detected.

The plasma end point detecting method according to the second aspect of the present invention is performed in combination with the conventional end point detecting method, and always monitors the plasma emission during the plasma processing by the two methods. Is determined as the end point, and the end point is detected.

According to the present invention, the plasma emission in the plasma processing is always monitored by the two methods, and when both end point determination methods determine the end point of the plasma processing, the end point is determined and the end point is detected. The end point detection accuracy is improved, and the optimum and stable end point detection can always be performed.

According to a third aspect of the present invention, there is provided an end point detecting apparatus.
According to a second or third aspect of the present invention, there is provided a method using the means.

According to the present invention, a plasma end point detecting apparatus always performs an optimum end point detection by using the means of the second or third aspect, prevents erroneous detection of an end point of plasma processing, and provides a stable end point. Can be detected.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a plasma processing end point detecting method according to the first aspect of the present invention. A learning operation is performed once in order to store the waveform of the light emission intensity at a certain wavelength of the plasma light emission during the plasma processing under the conditions for processing the material to be plasma processed and the material to be plasma processed.

First, the spectroscope 1 captures only the light of a predetermined wavelength from the emission of the plasma when processing the material to be processed. The light taken in by the spectroscope 1 is converted into an electric signal of the emission intensity of the designated wavelength via the photoelectric converter 2 and the amplifier 3 and output to the waveform storage circuit 6. The waveform storage circuit 6 stores the change of the electric signal as a continuous waveform shape. Further, the signal of the amplifier 3 is converted into a digital signal by the analog-to-digital converter 4, and the signal processed by the arithmetic circuit 5 is stored in the waveform storage circuit 6.
Output to The waveform storage circuit 6 stores a change in the digital signal subjected to the arithmetic processing as a continuous waveform shape.

It should be noted that a plurality of waveform storage circuits 6 can be used to select which of the stored waveforms to use, so that a certain wavelength of the plasma emission under the conditions for processing the plasma processing material and the material to be plasma processed. It is possible to store a plurality of signal waveforms of the light emission intensity in the plasma processing chamber, and to cope with various plasma processing materials and plasma processing conditions in the plasma processing chamber.

Further, depending on the plasma processing chamber, the emission intensity of the designated wavelength fluctuates due to contamination of a window for monitoring plasma emission due to plasma processing, noise due to use of high frequency, and the like. Therefore, a margin is given to the continuous waveform shape of the signal stored in the waveform storage circuit 6. The margin of the waveform shape is preferably about 5 to 10% with respect to the obtained electric signal level being 100%. By giving a margin to the waveform shape, signal fluctuations due to noise or the like can be absorbed, and malfunction can be prevented.

Two signals before and after the arithmetic processing are input to the waveform storage circuit 6, and the waveform whose end point is easily determined is selected and used as a comparison basic waveform for the end point determination. When the plasma processing is performed thereafter, the comparison basic waveform in the waveform storage circuit 6 having the same plasma processing material and the same plasma processing conditions is compared with a signal obtained from light emission during the plasma processing by the comparison circuit 7 to perform plasma processing. Determine the end of processing.

As described above, since the waveform of the detected light emission intensity at a certain wavelength of the plasma light emission during the plasma processing is stored and compared with the stored waveform shape, the subsequent end point detection is performed. Optimal end point detection becomes possible.

(Embodiment 2) FIG. 2 is a block diagram of a plasma processing end point detecting method according to the second aspect of the present invention. In the same manner as in the first embodiment, in order to store the waveform of the light emission intensity at a certain wavelength of the plasma light emission during plasma processing under the conditions for processing the material to be plasma processed and the material to be plasma processed, as an electric signal. Perform the learning operation.

First, the spectroscope 11 takes in only the light of a predetermined wavelength from the emission of the plasma when processing the material to be processed. The light taken in by the spectroscope 11 is converted into an electric signal of the emission intensity of the designated wavelength via the photoelectric converter 12 and the amplifier 13 and output to the waveform storage circuit 16. The waveform storage circuit 16 stores the change of the electric signal as a continuous waveform shape. Further, the signal of the amplifier 13 is converted into a digital signal by the analog-to-digital converter 14, and the signal processed by the arithmetic circuit 15 is output to the waveform storage circuit 16. The waveform storage circuit 16 stores a change in the digital signal subjected to the arithmetic processing as a continuous waveform shape.

By providing a plurality of waveform storage circuits 16 and making it possible to select which of the stored waveforms to use, the plasma processing material and the plasma emission under the conditions for processing the plasma processing material can be obtained. It becomes possible to store a plurality of signal waveforms of the light emission intensity at the wavelength, and it is possible to correspond to various plasma processing materials and plasma processing conditions in the plasma processing chamber.

Further, depending on the plasma processing chamber, the emission intensity of the designated wavelength fluctuates due to contamination of a window for monitoring plasma emission by plasma processing, noise due to use of high frequency, and the like. Therefore, a margin is given to the continuous waveform shape of the stored signal. The margin of the waveform shape may be about several percent with the obtained electric signal level being 100%.

The waveform storage circuit 16 stores two data before and after the arithmetic processing.
Although two signals are input, the waveform that is easier to determine the end point is selected and used as the comparison basic waveform for the end point determination.

When the plasma processing is performed thereafter, a comparison basic waveform in the waveform storage circuit 16 having the same plasma processing conditions as the material to be plasma-processed and a signal obtained from light emission during the plasma processing are compared by the comparison circuit 17. After the comparison, a plasma processing end signal is sent to the end point determination circuit 18.

On the other hand, in the end point detection method used in the plasma processing, which is a conventional technique, in the same manner as described above, the emission of the plasma when the material to be plasma-processed is processed is measured by the spectroscope 1.
Only light of a certain wavelength designated in advance by 1 is taken in. In this case, the wavelength to be taken is the same as that of the same material to be processed and the same plasma processing conditions stored in the waveform storage circuit in advance. The light taken in by the spectroscope 11 is converted into an electric signal of the emission intensity of the designated wavelength via the photoelectric converter 12 and the amplifier 13 and output to the end point detection circuit 19. Further, the signal of the amplifier 13 is converted into a digital signal by the analog-to-digital converter 14, and the signal processed by the operation circuit 15 is output to the end point detection circuit 19. The end point detection circuit 19 receives two signals before and after the arithmetic processing. Signals for which the end point can be easily determined are selected in advance and the end point detection conditions are set.
Based on the signal input at the end point, the end point detection circuit 19
When the end point detection condition set in advance is satisfied, it is determined that the plasma processing has ended, and a processing end signal is sent to the end point determination circuit 18.

The processing determination circuit 18 determines the end point of the plasma processing when the two signals of the comparison circuit 17 and the conventional end point detection circuit 19 are obtained.

As described above, the plasma emission during the plasma processing is always monitored by the two methods, and the end point is determined when both of the end point determination methods determine the end point of the plasma processing, and the end point is detected. Is improved, and an optimum and stable end point can be always detected.

(Embodiment 3) FIG. 3 is a block diagram of a plasma etching apparatus according to an embodiment using a plasma processing end point detecting apparatus according to the third aspect of the present invention.

By using the method of the first or second embodiment, the emission intensity at a certain wavelength of the plasma emission during the plasma processing under the conditions for processing the plasma processing material and the plasma processing material is converted into an electric signal. Perform a learning operation once to memorize the obtained waveform.

The material to be etched 26 is placed on the electrode 27 in the plasma processing chamber 25, and an etching process is performed. A process gas controlled to a set amount by the gas flow controller 24 is introduced into the plasma processing chamber 25. The microwave generated by the microwave oscillator 21 is introduced from the upper part of the plasma processing chamber 25 through the matching unit 22. Electrons resonate and oscillate in the plasma processing chamber 25 due to the magnetic field and the microwaves generated by the magnets 23, and the electrons form secondary plasma states. A high-frequency oscillator 28 is connected to an electrode 27 that is electrically insulated from the periphery by an insulator, and a bias is applied by high frequency to draw reactive species into the material 26 to be etched on the electrode 27 to perform etching.

Light having a specified wavelength of plasma emission generated by the etching process is taken in by a spectroscope 29 and sent to a plasma processing end point detecting device 30. The detailed configuration of the plasma processing end point detection device 30 is shown in FIG.
7 correspond to portions indicated by 12 to 19 in FIG. In the plasma processing end point detection device 30, 6 in FIG. 1 or 1 in FIG.
In a waveform storage circuit corresponding to No. 6, a signal waveform of a predetermined wavelength of plasma emission, which is designated in advance, is stored.

The material to be etched and the material to be etched can be selected by using a plurality of waveform storage circuits corresponding to 6 in FIG. 1 or 16 in FIG. Of plasma emission under processing conditions,
It becomes possible to store a plurality of signal waveforms of light emission intensity at a certain wavelength, and it is possible to cope with various materials to be etched and etching processing conditions in a plasma processing chamber.

A plasma processing end signal is output from the plasma processing end point detecting device 30 to the device CPU 31. Upon receiving the signal, the apparatus CPU 31 transmits a plasma processing stop to each unit, and ends the plasma processing.

Further, the plasma end point detecting device 30 comprises:
In addition to the above-described embodiment, the present invention can be applied to an apparatus for automatically stopping plasma processing using plasma emission.

As described above, the plasma processing end point detecting device 30
By using the means of the second or third aspect, there is an effect that an optimum and stable end point is always detected, an erroneous detection of the end point of the plasma processing is prevented, and a stable end point can be detected.

[0037]

According to the first aspect of the present invention, the waveform of the detected light emission intensity at a certain wavelength of the plasma light emission during the plasma processing is stored and compared with the stored waveform shape. Then, since the end point is detected thereafter, there is an effect that the optimum and stable end point can be always detected.

According to the second aspect of the present invention, the plasma emission during the plasma processing is always monitored by the two methods, and the end point is determined when both of the end point determination methods determine the end point of the plasma processing. Is carried out, the end point detection accuracy is improved, and there is an effect that optimum and stable end point detection is always possible.

According to a third aspect of the present invention, there is provided a plasma end point detecting apparatus using the means of the second or third aspect.
There is an effect that optimum and stable end point detection is always performed, erroneous detection of the end point of plasma processing is prevented, and stable end point detection can be performed.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a plasma processing end point detecting method according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a plasma processing end point detecting method according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram of a plasma etching apparatus showing an embodiment using the plasma processing end point detection apparatus of the present invention.

FIG. 4 is a configuration diagram of a conventional plasma processing end point detection apparatus.

[Explanation of symbols]

 1. Spectroscope 2. Photoelectric converter 3. Amplifier 4. Analog-to-digital converter 5. Operation circuit 6. 6. Waveform storage circuit Comparison circuit 11. Spectroscope 12. Photoelectric converter 13. Amplifier 14. Analog-to-digital converter 15. Operation circuit 16. Waveform storage circuit 17. Comparison circuit 18. Processing determination circuit 19. End point detection circuit 21. Microwave oscillator 22. Matching device 23. Magnet 24. Gas flow controller 25. Plasma processing chamber 26. Material to be etched 27. Electrode 28. High frequency oscillator 29. Spectrometer 30. Plasma processing end point detection device 31. Device CPU 41. Spectrometer 42. Photoelectric converter 43. Amplifier 44. Analog-to-digital converter 45. Arithmetic circuit 46. End point detection circuit 47. Device CPU

Claims (3)

[Claims] 1. A method for storing an emission intensity waveform shape of a plasma emission at a certain wavelength, and comparing the stored waveform shapes at all times to detect an end point of the plasma processing. 2. A method for detecting an end point of plasma processing by simultaneously performing the conventional end point detection method and the method of claim 1. 3. An end point detecting apparatus using the means according to claim 2.