JP3350264B2 - Plasma cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma cleaning method in a plasma CVD apparatus.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor integrated circuit, a plasma CVD method capable of forming a film at a low temperature is known as a method of depositing a silicon nitride film or a silicon oxide film in a process after formation of a wiring made of aluminum. ing. FIG. 1 shows a schematic view of an example of a plasma CVD apparatus used for manufacturing a semiconductor integrated circuit. In FIG. 1, an upper electrode 1 and a lower electrode 2 are arranged in parallel in a vacuum vessel 3 with a distance 8 between the electrodes. The semiconductor substrate 7 is placed on the lower electrode 2.
On the lower electrode 2 side of the upper electrode 1, a gas inlet 4 having an infinite number of holes with an inner diameter of 0.4 to 1.0 mm is provided. Upper electrode 1
Is connected to a high-frequency power source 5 for the upper electrode, and the lower electrode 2 is connected to a high-frequency power source 6 for the lower electrode. The reaction gas is introduced from the gas inlet 4 into the vacuum vessel 3. Further, a vacuum exhaust port 9 for maintaining the inside of the vacuum vessel 3 at a predetermined pressure is provided at a lower portion of the vacuum vessel 3.

The frequency of the upper electrode high frequency power supply 5 is 13.56 MHz, and the frequency of the lower electrode high frequency power supply 6 is 450 kHz.
In general, power having a frequency of 1 MHz or more is applied to one side, and power having a frequency of 200 kHz to 1 MHz is applied to the other side.

When a high-frequency current of 1 MHz or more supplied from the upper electrode 1 and flowing to the lower electrode 2 flows to the ground, a capacitor 10 supplied from the lower electrode high-frequency power supply 6
This is for preventing a high frequency current of z or less from flowing directly to the ground. A current of a frequency of 1 MHz or more flowing from the upper electrode 1 flows, and a frequency of 1 MHz or less supplied from the high frequency power supply 6 for the lower electrode. The capacity is set so that the current does not flow.

When a high frequency current of 1 MHz or less supplied from the lower electrode 2 and flowing to the upper electrode 1 flows to the ground, the high frequency current of 1 MHz or more supplied from the high frequency power supply 5 for the upper electrode is directly grounded. 1 MH flowing from the lower electrode 2
A current having a frequency of z or less flows, and a high-frequency power supply 5
The inductance is adjusted so that a current of 1 MHz or more supplied from the device does not flow.

The semiconductor substrate 7 is formed by a plasma CVD method.
When an insulating film is deposited thereon, the film is deposited also on the inner walls of the upper electrode 1, the lower electrode 2, and the vacuum vessel 3. This deposit is
It peels off during the reaction or during transportation of the semiconductor substrate and becomes dust. Further, if the deposits are clogged in the holes of the gas introduction ports 4 provided in the upper electrode 1, the uniformity of the deposition rate in the substrate deteriorates.

For this reason, after the film deposition step by the plasma CVD method is completed, the semiconductor substrate 7 is temporarily moved out of the vacuum vessel 3.
After discharge, a plasma cleaning method is employed in which an etching gas is introduced into the vacuum vessel 3 to generate plasma, thereby removing films deposited on the upper electrode 1, the lower electrode 2 and the inner wall of the vacuum vessel 3. In this plasma cleaning method, the etching gas is excited by thermionic electrons in the plasma to generate an etchant that has become a reactive gas, and the etching proceeds with the etchant. After the end of the etching, there is no deposit to be etched, the emission spectrum is significantly different from that during the etching, and the emission state changes.

In the above-described plasma cleaning method, a state in which the distance 8 between the electrodes is reduced (for example, the upper electrode 1
And 1/10 or less of the maximum diameter of the smaller electrode of the lower electrode 2).
Since it is confined between the upper electrode 1 and the lower electrode 2, the speed of etching the film deposited on the upper electrode 1 and the lower electrode 2 is significantly increased. This plasma cleaning method is hereinafter referred to as narrow gap plasma cleaning. In the narrow gap plasma cleaning, the film deposited on the upper electrode 1 and the lower electrode 2 can be removed at a high speed, but the density of plasma existing in a space other than between the upper electrode 1 and the lower electrode 2 in the vacuum vessel 3 is low. For,
The film deposited on the inner wall of the vacuum vessel 3 cannot be removed.

On the other hand, a state in which the interelectrode distance 8 is increased (for example, the maximum diameter of the upper electrode 1 and the lower electrode 2 is set to be at least 1/10 of the maximum diameter of the smaller electrode).
When the plasma cleaning is performed, the density of the plasma between the upper electrode 1 and the lower electrode 2 becomes low, and the plasma spreads over the entire vacuum vessel 3 and the film deposited inside the vacuum vessel 3 can be removed. Since the plasma density between the lower electrode 1 and the lower electrode 2 is low, the etching rate of the deposit on the upper electrode 1 and the lower electrode 2 is reduced.
In order to remove even the film deposited on the surface, a long cleaning is required.

Due to the above-described features of both the narrow gap plasma cleaning and the wide gap plasma cleaning, the two cleaning methods are used together in order to completely and rapidly clean the inside of the vacuum vessel 3.

First, when switching to narrow gap plasma cleaning after performing wide gap plasma cleaning, it is difficult to determine when to switch to narrow gap plasma cleaning. As described above, when the substance to be etched is exhausted, the emission state of the plasma of the etching gas changes.However, when the wide gap plasma cleaning is switched to the narrow gap plasma cleaning before the change in the emission state of the plasma occurs. There is a problem that a film deposited on a portion other than the upper electrode 1 and the lower electrode 2 such as the inner wall of the vacuum vessel 3 may not be completely removed, and there is a problem that it is not removed even after that. Conversely, if wide-gap plasma cleaning is performed until the light emission state of the plasma changes, there is a problem that cleaning takes a long time, and narrow gap plasma cleaning is not necessary.

Therefore, when both cleaning methods are used in combination, if the cleaning is to be performed completely in the minimum necessary cleaning time, the narrow gap plasma cleaning is performed first, and after the light emission state of the plasma changes. That is, the wide gap plasma cleaning is performed after all the deposits on the upper electrode and the lower electrode to be removed by the narrow gap plasma cleaning are removed.

[0013]

As described above, when complete cleaning is performed only by wide gap plasma cleaning, a two-stage cleaning method in which wide gap plasma cleaning is performed after narrow gap plasma cleaning is performed. There is a problem that the cleaning time is about twice as long as the cleaning time.

When a two-stage cleaning method is used in which narrow gap plasma cleaning is performed and wide gap plasma cleaning is performed after the light emission state of the plasma is changed, the cleaning time is reduced, but the particle size called dust is 0.3 μm. There is a problem that a large number of particles are generated in a vacuum vessel, and this dust is taken into a film deposited by a plasma CVD method.

The present inventors conducted an experiment in which a film was deposited on the semiconductor substrate 7 using the plasma CVD apparatus shown in FIG. 1 and then narrow gap plasma cleaning was performed to observe the state of dust generation. As a result, when the narrow gap plasma cleaning is being performed, a large amount of dust is generated in the vacuum container 3 immediately before the light emission state of the plasma greatly changes.
A phenomenon that began to occur inside was observed. In the cleaning using only the wide gap plasma cleaning, the phenomenon of dust generation was hardly observed.

From the above results, narrow gap plasma cleaning, which is a high-speed and low-dust plasma cleaning method in which the distance between the two upper electrodes 1 and lower electrodes 2 is reduced, is significantly changed in the plasma emission state. High-speed and low-dust plasma cleaning is realized by combining the process that is completed before cleaning and the process of performing wide-gap plasma cleaning in which cleaning is performed by widening the distance between the two upper electrodes 1 and lower electrodes 2. it can.

However, in a normal production apparatus, each process is controlled by time. However, the deposition rate fluctuates due to the problem of reproducibility, and thus the thickness of the deposited film fluctuates. Or become. As a countermeasure, there is a method of installing an end point monitor (a method of monitoring the light emission state of plasma with a sensor), but the cost becomes high as a production apparatus.

The present invention solves the above-mentioned problems in the prior art, and uses a combination of narrow gap plasma cleaning and wide gap plasma cleaning, and changes the state of application of electric power. It is an object to provide a cleaning method.

[0019]

According to the present invention, in order to achieve the above object , high frequency power is applied to two electrodes in a vacuum vessel.
Plasma is generated by applying
Using plasma, the electrodes and the inner wall of the vacuum vessel
Plasma cleaning method for cleaning
Te, to narrow the distance of the two electrodes, mark one electrode
High-frequency power pressure stops, performing a first step of performing cleaning, the cleaning until immediately after said plasma emission state in the first step is greatly changed by applying a power having a frequency only in the above 1MHz other electrode a second step, after the wide distance between the two electrodes, and wherein <br/> Rukoto to have a, and a third step of performing cleaning by applying high frequency power to the two electrodes I do.

Further, the first step is performed by setting the distance between the two electrodes to be 1/10 or less of the maximum diameter of the electrode having the smaller maximum diameter of the two electrodes, and the distance between the two electrodes is reduced. However, it is preferable that the third step is performed by making the maximum diameter of the two electrodes smaller than the maximum diameter of the electrode having the smaller diameter.

In the first step, cleaning is performed by supplying power of 1 MHz or more to the first electrode, and in the third step, power of 1 MHz or more is supplied to the first electrode and the second electrode is subjected to cleaning. It is preferable to perform cleaning by supplying power of 1 MHz or less to the cleaning device.

[0022]

As described above, when the narrow gap plasma cleaning is used and the two-stage cleaning method of performing the wide gap plasma cleaning after the light emission state of the plasma is changed, a large amount of dust is generated, and the dust is deposited by the plasma CVD method. It was known that this dust was taken into the film, but the cause of dust generation was not clear.

The inventors of the present invention conducted a narrow gap plasma cleaning after depositing a film on a semiconductor substrate using the plasma CVD apparatus shown in FIG. 1 and conducted an experiment for observing the state of dust generation. Clarified the process. As a result, when performing narrow-gap plasma cleaning, a phenomenon was observed in which a large amount of dust began to be generated in the vacuum vessel immediately before the plasma emission state changed significantly. As mentioned earlier, this phenomenon was hardly observed. Further, in the case of narrow-gap plasma cleaning using only high-frequency power of 1 MHz or more, no phenomenon that dust starts to be generated in the vacuum vessel was observed at all even after the plasma emission state changed significantly.

The mechanism of this dust generation is considered as follows.

In the narrow gap plasma cleaning, since the upper electrode and the lower electrode are close to each other, the electric field due to the applied high frequency power is strong in the space between the upper electrode and the lower electrode. Becomes weaker at the edges of the space, and becomes weaker in other spaces. Therefore, the plasma of the etching gas is gathered in the space between the upper electrode and the lower electrode, the plasma density in the peripheral portion is low, and the kinetic energy of the plasma particles is weak. When the upper electrode and the lower electrode have a large amount of deposits to be etched, most of the etchant is consumed for etching the upper electrode and the lower electrode surface which are in contact with the region where the plasma density is high, and thus occupies the plasma diffused to the peripheral portion. The amount of etchant is small. Therefore, the peripheral portion is hardly etched.

However, if there is no deposit to be etched on the upper and lower electrode surfaces in contact with the region having a high plasma density, the etchant is not consumed for etching the upper and lower electrodes. The amount of unreacted etching gas plasma in the plasma diffused to the edge increases. Therefore, the upper electrode,
Etching of the edge of the lower electrode proceeds. However, the etching of the edges of the upper electrode and the lower electrode by the etchant selectively etches weak portions of the film because the plasma density is low and the kinetic energy of the plasma particles is low. The portion having a high film quality is also impacted by the plasma, and the fixing force is reduced. For this reason, it turned out that the strong film | membrane part surrounded by the weak film | membrane part peeled off and became dust. It was also found that most of the dust came from the edges of the upper and lower electrodes where the amount of the etchant diffused was large.

On the other hand, in the wide gap plasma cleaning, the plasma spreads throughout the vacuum chamber, and the plasma density and the kinetic energy of the plasma particles are lower than in the narrow gap plasma cleaning. It is higher than the density of plasma diffused to the edges of the upper and lower electrodes and the kinetic energy of plasma particles. Therefore, in the wide gap plasma cleaning, the selective etching as described above is not performed, and no dust is generated.

It has been experimentally confirmed that the particles hardly diffuse when the particles in the plasma vibrate with a large amplitude. When a high frequency power of 1 MHz or less is applied, both electrons and ions oscillate with sufficient amplitude. However, when only high-frequency power of 1 MHz or more is applied, electrons have a small mass and oscillate following this power, so that sufficient amplitude can be obtained, but ions have a heavy mass and follow this power. Even if it vibrates, the amplitude is very small. Therefore, when only high-frequency power of 1 MHz or more is applied, electrons do not diffuse from between the upper electrode and the lower electrode, but ions diffuse from between the upper and lower electrodes due to small amplitude.

Based on the above findings, the operation of the present invention will be described below.

In the first step of the present invention, if the distance between the upper electrode and the lower electrode is reduced, a strong electric field is limited between the upper electrode and the lower electrode, and the electric field becomes weak in other spaces. The plasma is generated in this narrow area. If only electric power of a frequency of 1 MHz or more is applied, sufficient amplitude cannot be obtained for ions, and therefore, an attempt is made to diffuse the region into a weak electric field. However, electrons are hardly diffused, and if only ions are diffused, the charge distribution becomes non-uniform and is pulled back by Coulomb force. Therefore, diffusion of ions is limited to the vicinity where electrons are confined.

By the way, the etchant to be etched is ionized by turning the etching gas into plasma. Therefore, when only power of a frequency of 1 MHz or more is applied, the edges of the upper electrode and the lower electrode are also applied. Spread etching is performed. At this time, since the plasma density of the etching gas and the kinetic energy of the plasma particles are sufficiently high, selective etching is not performed on a portion having a low film quality, and the etching is uniformly performed on a portion having a high film quality. Does not occur.

[0032] In the above first step before the plasma emission state changes, i.e. only by applying a 1MHz or more high-frequency power before the occurrence of dust occurs by spalling (second step), the largest dust source Can be cleaned without generating dust.

In the third step, when high-frequency power is applied by widening the gap between the upper electrode and the lower electrode, the electric field spreads at the edges of the upper electrode and the lower electrode. Gap plasma cleaning is performed over a wide area in the vacuum vessel. The density of the plasma spread in the vacuum vessel is lower than that in the case of the narrow gap plasma cleaning, but the etching is not dilute and does not generate dust until the selective etching is performed. Therefore, the inner wall of the vacuum vessel, the upper electrode, and the lower electrode can be etched without generating dust.

Therefore, according to the method of the present invention, when the cleaning is performed, high-speed cleaning of the upper electrode and the lower electrode, which is a feature of the narrow gap plasma cleaning, is performed.
It is compatible with wide-area cleaning inside the vacuum chamber, which is a feature of wide gap plasma cleaning, and has a feature that can solve the problem of dust generation at the final stage of narrow gap plasma cleaning without an endpoint monitor. Therefore, the inside of the vacuum container can be completely cleaned at high speed.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a plasma CV used for depositing a silicon nitride film for a protective film in a manufacturing process of a semiconductor integrated circuit will be described.
The cleaning process after the film deposition process by the method D is described as an example. The apparatus used in the experiment was a 6-inch plasma CVD apparatus for semiconductor substrates. Since the configuration of the device is the same as that of the conventional example shown in FIG. 1, the description of the device is omitted.

The formation of the silicon nitride film and the cleaning of the plasma CVD apparatus configured as described above will be described. With the semiconductor substrate 7 placed on the lower electrode 2 as shown in FIG.
CCM and ammonia 150SCCM from gas inlet 4 to vacuum vessel 3
The gas is evacuated from the evacuation port 9 while being introduced into the chamber, and the upper electrode 1 is supplied with 300
When a high frequency power of 100 W is applied to the lower electrode 2 and W, plasma is generated in the vacuum vessel 3, and a silicon nitride film can be deposited on the semiconductor substrate 7.

The plasma C configured as described above is used.
A plasma cleaning method after depositing a silicon nitride film on the semiconductor substrate 7 in the VD apparatus as described above will be described below.

As the first step, the following cleaning was performed. After the thin film is deposited on the semiconductor substrate 7 as described above, in a state where the semiconductor substrate 7 is not on the lower electrode 2, the interelectrode distance 8 is set to 13 mm, that is, 1/100 of the maximum diameter 160 mm of the upper electrode 1 having the smaller maximum diameter. 10 or less, sulfur hexafluoride 200SCCM
Evacuation is performed while introducing 50 SCCM of oxygen and 50 SCCM of oxygen from the gas inlet 4 into the vacuum vessel 3, and the 13.56 MHz high-frequency power 500 W is applied to the upper electrode 1 while maintaining the pressure in the vacuum vessel 3 at 800 mTorr.
Is applied, plasma is generated in the vacuum chamber 3 and narrow gap plasma cleaning can be performed.

At this point, the power applied to the electrode is only 13.56 MHz applied to the upper electrode 1, that is, 1 MHz.
Only the above power. In this case, the ions were diffused, and the light emission region of the plasma also spread to the electrode edges of the upper electrode 1 and the lower electrode 2, and it was confirmed that the film deposited on the electrode edges was being etched. However, since the plasma emission region does not extend to the inner wall of the vacuum vessel 3, the inner wall of the vacuum vessel 3 is not cleaned.

The light emission state is 3
At minute 05 seconds, the emission state of the plasma changed significantly, and the spectrum of the fluorine atoms reached a peak. At this point, the cleaning of the edges of the electrodes, in addition to the cleaning of the upper electrode 1 and the lower electrode 2 by the narrow gap plasma cleaning, has been completed. High frequency power of lower electrode 2
(1 MHz or less), when high-frequency power is applied only to the upper electrode 1, the plasma density between the electrodes is reduced because the etchant is diffused to the edge of the electrode, and cleaning of the edge of the electrode is also difficult. Since the cleaning is performed, the cleaning time for the upper electrode 1 and the lower electrode 2 is slightly longer.

Thereafter, as cleaning in the second step,
3 minutes and 05 seconds after the start of the first step, that is, when the light emission state of the plasma between the upper electrode 1 and the lower electrode 2 greatly changes, the application of the high-frequency power applied to the upper electrode 1 also stops,
The narrow gap plasma cleaning is completed. Then, as the cleaning in the third step, as described above,
The distance between the upper electrode 1 and the lower electrode 2 is changed to 28 mm, that is, 1/10 or more of the maximum diameter 160 mm of the upper electrode 1 having the smaller maximum diameter. Was started and wide gap plasma cleaning was performed, and continued until the light emission state of the plasma in the vacuum chamber 3 changed significantly.

In the cleaning at this stage, the region where the electric field is strong extends to the periphery of the upper electrode 1 and the lower electrode 2 , and
As described above, since the pressure is as low as 200 mTorr , the plasma emission region also reaches the wall surface of the vacuum vessel 3 and extends not only to the peripheral portions of the upper electrode 1 and the lower electrode 2 such as the wall surface of the vacuum vessel 3 but over a considerably wide range. Cleaning is performed. In this cleaning, the light emission state of the plasma changes, and when the cleaning is completed, the deposited film in the vacuum vessel 3 has been almost completely removed.

After the completion of this cleaning, as described above,
When a silicon nitride film was deposited on the semiconductor substrate 7 by a plasma CVD method, the number of dusts incorporated in the silicon nitride film was about 20 or less. Significantly reduced. The number of dusts confirmed here is almost the same as the number of dusts generated even when the cleaning is performed only by the wide gap plasma cleaning, and it is considered that the number of dusts is not the dust due to the separation of the deposits.

In the narrow gap plasma cleaning, the total time required from the start to the end of the cleaning is also
It was only about 10 seconds longer than in the case of the following comparative example in which power was applied to the lower electrode 2. That is, plasma cleaning was performed at high speed with little generation of dust.

For comparison with the above-mentioned embodiment of the present invention, the following comparative experiment was conducted by a conventional plasma cleaning method.

Also in the comparative example, cleaning was performed after depositing a silicon nitride film. First, narrow-gap plasma cleaning is performed in the same manner as in the first step of this embodiment, and the emission state of the plasma between the upper electrode 1 and the lower electrode 2 changes two minutes and 50 seconds after the start, and the color of the discharge becomes blue-white. From red to red was confirmed. Here, the discharge is temporarily stopped, the distance between the upper electrode 1 and the lower electrode 2 is changed to 28 mm and the pressure in the vacuum vessel 3 is set to 200 m as in the second step of the present embodiment.
After the pressure was reduced to Torr, discharge was started again, wide-gap plasma cleaning was performed, and the process was continued until the light emission state of the plasma changed significantly.

After the cleaning, a silicon nitride film was deposited on the semiconductor substrate 7 by a plasma CVD method.
It was found that 0 or more dust was taken in.

In order to examine the relationship between the light emission state and the light emission spectrum, a spectroscopic analysis was performed in this experiment, and when the light emission state was measured for fluorine atoms (wavelength 704 nm), the spectrum of the fluorine atoms immediately before the light emission state of the plasma changed significantly. Gradually increased, and the emission spectrum of the fluorine atom reached a peak when the emission state changed significantly. That is, when the light emission state changes significantly, the upper electrode 1, the lower electrode 2
It can be seen that the etching has already been completed.

In the above embodiment, the plasma cleaning step after the film deposition step by the plasma CVD method used in the manufacture of a semiconductor integrated circuit has been described.
The present invention is also applicable to a cleaning method in another plasma CVD apparatus such as a VD apparatus.

In the above embodiment, the cleaning step after the film deposition step by the plasma CVD method used for depositing the silicon nitride film for the protective film has been described as an example. However, another film, for example, a silicon oxide film or the like may be used. The present invention is also applicable to a cleaning process after the film deposition process by the plasma CVD method used for deposition.

Further, in the above-described embodiment, an example in which sulfur hexafluoride and oxygen are used as the etching gas has been described, but the etching gas may be another gas. For example, for a silicon nitride film, C ₂ F ₆ (dicarbon hexafluoride), N
Various gases such as F ₃ (nitrogen trifluoride) can be used.

In the above embodiment, the case where the distance between the upper electrode 1 and the lower electrode 2 in the narrow gap plasma cleaning is 13 mm and the distance between the upper electrode 1 and the lower electrode 2 in the wide gap plasma cleaning is 28 mm is described. However, as a rough guide for distinguishing the two, the distance between the upper electrode 1 and the lower electrode 2 is not more than 1/10 of the maximum diameter of the smaller one of the two upper electrodes 1 and the lower electrode 2. In this case, the density of the plasma generated between the upper electrode 1 and the lower electrode 2 is sufficiently high, and the etching of the upper electrode 1 and the lower electrode 2 is performed at high speed. If the distance between the lower electrode 2 and the lower electrode 2 is at least 1/10 of the maximum diameter of the smaller one of the two electrodes, the plasma is true. Since diffuse into the container 3, it can be regarded as a wide gap plasma cleaning.

In the above embodiment, 13.5
6 MHz and 450 kHz for lower electrode 2, but 45 kHz for lower electrode 2
The high-frequency power of 0 kHz may be within a range of 1 MHz or less so that ions in the plasma can follow the high-frequency vibration and are confined between the upper electrode 1 and the lower electrode 2. Conversely, the upper electrode 1 has a 1 MH at which ions cannot follow and vibrate.
It is sufficient if it is z or more. Further, the lower limit of the frequency is desirably 200 kHz or more in consideration of the stress controllability of the film formation. The critical value of 1 MHz is a value found by the present inventors through experiments.

[0054]

As described above, the plasma cleaning method of the present invention can provide an inexpensive plasma cleaning method that is fast and generates less dust.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a plasma CVD apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Upper electrode, 2 ... Lower electrode, 3 ... Vacuum container, 4
... Gas inlet, 5 ... High frequency power supply for upper electrode, 6 ... High frequency power supply for lower electrode, 7 ... Semiconductor substrate, 8 ... Distance between electrodes, 9 ... Vacuum exhaust port.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-97154 (JP, A) JP-A-6-224163 (JP, A) JP-A-63-244739 (JP, A) 221620 (JP, A) JP-A-7-335556 (JP, A) JP-A-7-335617 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/3065 C23C 16 / 00-16/56 H01L 21/205

Claims (3)

(57) [Claims] 1. Two electrodes in a vacuum vesselHigh frequency power
By applying this, plasma is generated and the etching gas
Using plasma, the electrode and the inner wall of the vacuum vessel
Plasma cleaning method for cleaning
hand,  By narrowing the distance between the two electrodesIs applied to one of the electrodes.
High-frequency power stops and only the other electrode1MHz or more
Apply frequency powerTeFirst step of leaning
When,  Immediately after the light emission state of the plasma greatly changes in the first step.
rearA second step of cleaning up to  Increase the distance between the two electrodesAfterThe two electrodes
Apply high frequency power toTeThe first to do the leaning3Process
When, Have A plasma cleaning method. 2. The first step is performed by setting a distance between the two electrodes to be 1/10 or less of a maximum diameter of an electrode having a smaller maximum diameter of the two electrodes, and performing a distance between the two electrodes. 2. The plasma cleaning method according to claim 1, wherein the third step is performed by making the maximum diameter of the electrode having a smaller diameter of at least 1/10 or more of the two electrodes. 3. The method according to claim 1, wherein in the first step, 1 MH is applied to the first electrode.
Cleaning is performed by supplying power of z or more, and the third
3. The plasma cleaning method according to claim 1, wherein the cleaning is performed by supplying a power of 1 MHz or more to the first electrode and a power of 1 MHz or less to the second electrode.