JPH01226154A - Plasma treatment equipment - Google Patents

Abstract

PURPOSE:To detect the end point of a plasma treatment easily by providing a means wherein the input signal of the periodically varying emission intensity in a plasma is smoothened by an external means. CONSTITUTION:A lighting window 9 for a plasma light is provided on the side surface of a treatment chamber 1 and the light is transmitted through a spectroscope 10 while the emission wavelengths of reaction products are selected. The transmitted light intensity is converted into an electric signal and amplified by a photomultiplier 11 and an amplifier 12. The signal is smoothened by a low-pass filter 13 and offsetted by an adder 14. The signal is inputted to a microcomputer 17 through an analog-digital converter 16. The microcomputer 17 detects the terminal by using an end point detection algorithm in accordance with inputted data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma processing apparatus, and particularly to a plasma processing apparatus suitable for a case where the emission state of plasma changes periodically.

[Conventional technology]

Conventional plasma processing, for example, a method for determining the end point of etching, as described in JP-A No. 59-94423, involves quadratic temporal differentiation of the luminescence intensity of reaction products generated during the etching process, and There is a method that detects that a threshold value (setting a) for a set second-order differential value has been exceeded and performs an end point check.

[Problem to be solved by the invention]

The above-mentioned prior art is based on the premise that the plasma state is stable in a constant state during etching.

On the other hand, there have been remarkable technological advances in recent etching methods, such as the magnetron etching method, which uses a magnetic field to generate strong plasma to perform etching at high speed. In this Yuzu etching method, in order to improve the uniformity of the etching speed, a method is used to rotate the magnet for generating the magnetic field, and in this case, the area where a small amount of plasma is generated is affected by the rotation of the magnet. It changes periodically accordingly. At this time,
As shown in Figure 2(a), the emission intensity also changes periodically,
The conventional method for determining the final point does not take into consideration the case where the plasma emission state changes in this way, so there is a problem in that it is difficult to determine the end point and the processing accuracy deteriorates.

An object of the present invention is to provide a plasma processing apparatus that can easily determine the end point of plasma processing even when the plasma state changes periodically.

[Means to solve the problem]

The above object is achieved by providing an apparatus having a plasma processing detection circuit equipped with a smoothing means for smoothing an input signal of the luminescence intensity in the plasma which changes periodically by an external means.

[For production]

By providing a smoothing means in the plasma processing detection circuit,
Since the periodic change in the input signal of the periodically changing emission intensity in the plasma becomes smooth, it is possible to easily determine the end point of plasma processing.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to Section 1 and FIG. 2.

In FIG. 1, a processing chamber 1 is evacuated from an exhaust hole 2 by an exhaust system (not shown), and inside the processing chamber 1, &3 and an upper electrode 4 are arranged at a lower part 81 facing each other, and a lower S electrode 3
High-frequency power can be applied to the high-frequency power source 5 by means of a high-frequency power supply. A rotatable magnet 6 is provided on the back side of the upper 81iL pole 4, and can be eccentrically rotated by a rotation drive device 7 installed outside the processing chamber l.

In addition, a plasma light lighting window 9 is provided on the side of the processing chamber l,
The emission wavelength of the reaction product is selected and passed through the spectrometer 1O, the emission intensity is converted and amplified into an electric signal by the photomultiplier tube 11 and the amplifier 10, and the emission wavelength is amplified by the photomultiplier tube 11 and the amplifier 10. The signal is then passed through a gain amplifier, and is further inputted via an A/DI converter 16 to a microcomputer 17 which is a voltage determining means.

The microcomputer 17 converts the offset value from the adder 14 into m! via the D/A converter 18. I! It is possible to adjust the gain of gain amplifier b, and it is possible to turn off one of the 11 sources of high frequency t#5. The microcomputer 17 stores an algorithm for determining the end point of etching based on preset values, and calculates, for example, a secondary image component value of the emission intensity based on the data from the low-pass filter 13. , the end point is determined by comparing the calculated value and the set value, and when the end point is determined, the high frequency t#5
The application of high frequency voltage is stopped.

With the plasma processing apparatus configured as described above.

Plasma treatment 1, for example, a sea urchin to be etched 8, is placed on top of the upper electrode 3, and a treatment gas is introduced into the treatment chamber 1 by an unillustrated mechanism, and high frequency power is applied. At this time, due to the interaction between the electric field from the high-frequency power source 5 and the magnetic field from the magnet 6, plasma with strong emission intensity can be generated. At this time, the plasma becomes partially high-density due to the influence of the magnetic field, so the magnet 6 is rotated to make the etching process uniform.

Therefore, periods of strong and weak plasma appear periodically in the processing chamber 1 in accordance with the rotation of the magnet 6, and at this time, the signal which is multiplied by m width at the amplifier terminal via the photomultiplier tube 11 is As shown in figure (a), ◆The hand moves in two cycles T (changes and changes in a big way).

By passing the periodically fluctuating signal through the low-pass filter 13, the periodically fluctuating wave can be smoothed as shown by the solid line in FIG. 2(b).
This smoothed signal is offset by an adder 14 to make it easier to determine the end point, and the offset signal is amplified by a gain amplifier, and the A/D converter 1
6 to the microcomputer 17, the end point can be determined using the same end point determination algorithm that does not have periodic fluctuations in the plasma emission intensity.

At this time, the input signal entering the microcomputer 17 is slightly delayed in time by passing through the low-pass filter 13, resulting in a signal as shown by the solid line in FIG. 2(b). Here, the waveform shown by the dashed line is an ideal waveform when there is no time delay. However, this delay can be reduced by increasing the rotational speed of the magnet appropriately.

As described above, according to this embodiment, when determining the end point of etching using emission spectroscopy, even if the plasma emission intensity fluctuates periodically, the input signal can be passed through the low-pass filter 13. Since the periodic fluctuation portion can be smoothed, the end point can be easily determined.

Further, when smoothing is performed using the low-pass filter 13, it is easy to add it to the device and there is no need to change the software, so it can be easily implemented.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4.

In FIG. 3, the same reference numerals as in FIG. 1 indicate the same members. This figure differs from FIG. 1 in that a phase waveform synthesizer 19 is provided in place of the low-pass filter 13, which is the smoothing means in FIG.

The phase waveform synthesizer 19 manually inputs the signal having periodic fluctuations as shown in FIG. 2(a) that has passed through the amplifier 12, and
Based on the signal, a time-delayed signal, that is, a phase-shifted signal is created, and the non-phase-shifted signal and the phase-shifted signal are added together, averaged, and output. In this case, the phase waveform synthesizer 19 divides one period into three equal parts, that is, creates three signals with a phase shift of 28, as shown in FIG. 4 (a), (b), and (c). Add and average the three signals.

Further, in this case, the cycle in the one-phase waveform synthesis Ia 19 is set by receiving a signal from the rotation control swing that controls the rotation of the rotary drive device 7.

Note that when the rotation of the rotary drive bag M7 is constant, the period may be directly set in the phase waveform synthesizer 19, and in this case, the rotation controller is not necessary.

The functions of the other parts except for the phase waveform synthesizer 19 are the same as those of the H period embodiment, and the explanation thereof will be omitted.

As described above, according to the second embodiment of this report, even when the plasma emission intensity fluctuates periodically, it is possible to generate signals with different phases, add them, and average them. Since signals that fluctuate can be smoothed, it is possible to easily determine the end point.

In addition, in this embodiment, since signals with shifted phases are added, a time delay occurs in the output signal, but by appropriately increasing the rotation speed of the rotary drive device 7,
Delays are reduced.

Further, in this embodiment, the phase-shifted signals are generated by dividing one period into three equal parts, but the number of equal parts is not limited to this.

Next, a third embodiment of the present invention will be described with reference to FIG.

In FIG. 5, the same reference numerals as in FIG. 1 indicate the same members. The difference between this figure and FIG. 1 is that instead of the low-pass filter 13, which is the smoothing means in FIG.
A plurality of waveform combiners 21 (in this case, two) are provided, and the respective signals are input manually.

In this case, the spectrometer 10 divides the circumference equally into 18
00 position amount is provided, but two or more may be provided so as to equally divide the circumference.

The waveform synthesizer m receives the second
The system manually generates signals having periodic fluctuations as shown in Figure (a), adds the signals, averages them, and outputs the results. In this case, the signals manually input to the waveform synthesizer 21 are *< on the one hand, weakly fluctuating signals on the other hand, and detection signals at the same time are input manually.

The functions of the other parts except for the waveform synthesizer 4 are the same as those in the previous embodiment, and the explanation will be omitted.As described above, according to the third embodiment, i! ff - Similar to the example, even if the plasma emission intensity fluctuates periodically, the processing chamber! By capturing the light emitted from the plasma generated within the chamber at multiple locations, converting it into a signal, and then adding and averaging the signals, it is possible to smooth out signals that fluctuate over time.
This has the advantage that it is possible to easily determine the end point.

In addition, since the signals manually input to the waveform synthesizer 21 are signals at the same time, the smoothed signal does not have a time delay as in the first and second embodiments, and is more accurate. This has the effect of making it possible to determine the end point.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

In FIG. 6, the same reference numerals as in FIG. 1 indicate the same members. This figure differs from FIG. 1 in that a 4M9J intake controller n is provided in place of the low-pass filter 13, which is the smoothing means in FIG.

Signal acquisition controller n came through amplifier 12! I!
A signal having periodic fluctuations as shown in FIG. 2(a) is sampled intermittently in accordance with the period of the signal, for example, the signal value at the top of the waveform shown in FIG. 2(a). In this case, the rotary drive device 7 is driven at a constant rotation, and a setting value of the same rotation period as the rotation period of the rotary drive device 7 is set in the acquisition period setting field, and the signal sampling control device is set to a value that is the same as the rotation period of the rotary drive device 7. It is meant to indicate the timing.

In this way, the signal taken in in synchronization with the rotation period of the rotary drive device t7 can be considered to be the same as the signal input intermittently manually from a signal with no period fluctuation, so the amplifier 12
It is possible to smooth out a signal having periodic fluctuations.

Except for the signal acquisition controller n, the functions of the other parts are the same as in the legend, and detailed explanations will be omitted.

As described above, according to the fourth embodiment, the signal is sampled in accordance with the cycle of the periodically fluctuating signal even when the plasma emission intensity fluctuates periodically, as in the previous embodiment. Therefore, the signal under the same conditions of the cypress plasma emission state is inputted, which has the effect that periodically fluctuating signals can be smoothed and the end point can be easily determined.

In addition, the signal output from the signal acquisition controller n is the signal sampled by the signal acquisition controller η and is output as it is, and there is less time delay, so it has the effect that more accurate end point determination can be performed than in the previous embodiment. There is.

In these embodiments, the plasma emission state in the case of a device having an eccentrically rotating magnet 6 has been described.
As an external means, for example, the magnet 6 may be rotated around its axis, or a plurality of electromagnets may be provided and the electric power supplied to the electromagnets may be controlled to provide a rotating magnetic field. The effect is the same.

Furthermore, similar effects can be obtained by combining the respective embodiments described above.

〔Effect of the invention〕

According to the present invention, even when the plasma state changes periodically, the end point of plasma processing can be easily determined.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a plasma processing apparatus which is an embodiment of the present invention, FIG. 2(a) is a diagram showing the emission intensity of plasma generated by the apparatus of FIG. 1, and FIG. 2<b> 1 is a diagram showing the plasma emission intensity processed by the apparatus shown in FIG. 1, FIG. FIG. 5 is a configuration diagram showing a plasma processing apparatus according to a third embodiment of the present invention, and FIG. 6 is a fourth embodiment of the present invention. FIG. 1 is a configuration diagram showing a plasma processing apparatus. l... Processing chamber, lO... Spectrometer, 11
......Photoelectric multiplication t, 13...Low pass filter, 17...Microcomputer, 19
・・・・・・Phase waveform oxidizer, waveform synthesizer, n・・・・・・, signal acquisition controller l-\4 Agent: Patent attorney Katsuo Ogawa l'-゛1\6.
, +-,,,/ Figure 42 T Time t 3rd evil A 4

Claims (1)

[Scope of Claims] 1. A plasma processing apparatus characterized by having a plasma processing detection circuit equipped with a smoothing means for smoothing an input signal of the luminescence intensity in plasma which changes periodically by an external means. 2. The plasma processing apparatus according to claim 1, wherein the smoothing means passes the input signal through a low-pass filter. 3. The plasma processing apparatus according to claim 1, wherein the smoothing means adds to the input signal a signal value obtained by shifting the phase of the input signal. 4. The plasma processing apparatus according to claim 1, wherein the smoothing means detects light emission in the plasma using a plurality of detectors, and adds input signals detected by the detectors. 5. The plasma processing apparatus according to claim 1, wherein the smoothing means samples the input signal in accordance with the period of the input signal. 6. A method for determining the end point of plasma processing, which comprises smoothing an input signal of the luminescence intensity in the plasma that changes periodically by external means, and determining the end point of the plasma processing using the smoothed luminescence intensity.