JPS615521A - plasma processing equipment - Google Patents

Abstract

PURPOSE:To perform sufficient arriving vacuum degree by a simple and inexpensive method at vacuum evacuating time and to prevent a plasma processor from contaminating at a substrate removing time by moving opposed electrodes to electrically or mechanically connect a plurality of electrodes. CONSTITUTION:After a vacuum vessel 11 is evacuated by a vacuum evacuating system 15, one of upper and lower electrodes 12, 13 is moved to contact the both electrodes. The electrodes 12, 13 can be insulated from the vessel 11. In order to purity the inner wall of the vessel, inert gas or reactive gas is fed to the vessel 11, held in the prescribed pressure, and a plasma is generated between the electrodes 12, 13 and the vessel 11. The plasma impacts the electrodes 12, 13 and the inner wall of the vessel 11 to remove the adhered impurity and evacuates by the system 15. In this case, a substrate 14 is interposed between the electrodes 12 and 13, and since the both electrodes are the same potential, the influence of the plasma is not affected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a plasma processing apparatus capable of generating glow discharge plasma, and a substrate processing method using the apparatus.

[Background of the invention]

In conventional plasma processing equipment and substrate processing methods,
An inert gas that is adsorbed or adhered to the inner wall of the vacuum chamber during substrate mounting, etc., so that the impurity gas, etc. is desorbed from the inner wall of the vacuum chamber after evacuation, and is introduced into the vacuum chamber for substrate processing.

or reactive gas (hereinafter collectively referred to as substrate processing gas).

) is known to reduce the purity of

For example, when a substance is deposited, impurities mixed into the substrate processing atmosphere increase the impurity content of the deposited substance and deteriorate the film quality.

During etching, it reduces the reproducibility and controllability of etching speed. In addition, when cleaning the substrate surface,
Reduces the cleaning effect. In order to reduce the amount of impurities mixed into such a substrate processing atmosphere, it is important to improve the degree of vacuum achieved within the vacuum container before introducing the substrate processing atmosphere.

Generally, the pressure of the substrate processing gas should be
It is said that it is necessary to evacuate to a four-digit low pressure and then introduce substrate processing gas.

In conventional plasma processing equipment, the equipment is equipped with an expensive and large-sized vacuum pump, and exhaustion is performed for a long time to achieve this degree of vacuum. was. However, in both cases, the devices are large, complex, and expensive. In any case, the conventional plasma processing apparatus has a drawback in that it is extremely difficult to secure the required degree of vacuum in the vacuum chamber during evacuation before substrate processing. Furthermore, after the desired substrate processing is completed, the inner wall of the vacuum chamber is exposed to the atmosphere to take out the substrate, but at this time, the inner wall of the vacuum chamber is exposed to the atmosphere due to the reaction between the reactive gas adsorbed or attached to the inner wall and moisture in the air. It also had the disadvantage of being contaminated.

[Purpose of the invention]

In contrast, the purpose of the present invention is to achieve a sufficient degree of vacuum using a simpler and cheaper method during evacuation prior to desired substrate processing, and also to prevent equipment contamination when taking out the substrate. It is an object of the present invention to provide a plasma processing apparatus that enables high-quality film deposition, high-precision etching, effective substrate surface cleaning, etc. using the apparatus.

[Summary of the invention]

The present invention was made based on the knowledge that ion bombardment by plasma against the inner wall of a vacuum chamber is extremely effective for removing impurities existing on the surface of the inner wall subjected to the bombardment and improving the degree of vacuum during subsequent evacuation. It is something that In conventional plasma processing equipment, when plasma is generated, the substrate mounted on one of the two electrodes to which high-frequency power is applied is also exposed to the plasma at the same time, so the substrate is contaminated with impurities as described above. This results in the substrate being processed or damaged by the processing gas, and therefore, the above-mentioned plasma cleaning effect has not been utilized to clean the inner walls of the vacuum chamber. The present invention provides a plasma processing apparatus that makes it possible to utilize the cleaning effect of such plasma on the inner wall of a vacuum container, and a substrate processing method using the apparatus.

FIG. 1 shows the present invention, which has an upper electrode 12, a lower electrode 13, a vacuum exhaust system 15, a high frequency power source 16 and its changeover switches 17A1 and 17B, and a gas inlet 10 in a vacuum container (metallic, ground potential) 11. A typical example is shown below. As shown in FIG. 2A, a substrate 14 is mounted on the lower electrode 13. In this apparatus, after the inside of the vacuum container 11 is evacuated by the evacuation system 15, at least one of the upper electrode 12 and the lower electrode 13 is moved.

As shown in FIG. 6(b), it is possible to bring both electrodes into contact with each other. Further, both the upper electrode 12 and the lower electrode 13 can be insulated from the vacuum vessel 11. Next, in order to clean the inner wall of the vacuum container, an inert gas or a reactive gas (hereinafter collectively referred to as cleaning gas) is introduced into the vacuum container 11,
After maintaining the predetermined pressure, upper and lower electrodes 12.13,
Plasma is generated between the vacuum container 11 and the vacuum container 11. The plasma impacts the upper and lower electrodes 12, 13 and the inner wall of the vacuum vessel 11, knocks out the attached impurities, and discharges the vacuum exhaust system 15.
discharge by. At this time, the substrate 14 is sandwiched between the upper and lower electrodes 12 and 13, and is broken.

Since both electrodes 12 and 13 have the same potential, they are not affected by plasma. That is, in the apparatus of the present invention, it has become possible to perform plasma treatment only on the surfaces of the vacuum vessel 11 and the upper and lower electrodes 1, 2, and 13 without exposing the substrate 14 to plasma. After such plasma processing, desired substrate processing is performed to achieve high-quality film deposition, highly accurate etching, effective substrate surface cleaning, and the like. Moreover, if the above-mentioned vacuum container inner wall cleaning process is performed after desired substrate processing, contamination of the apparatus at the time of taking out the substrate can be prevented. In the above method example, the order of steps such as vacuum evacuation, contact between the upper and lower electrodes 12 and 13, and introduction of cleaning gas is arbitrary.

Also, opposing electrodes do not necessarily have to form a one-to-one pair; for example, a common electrode may have a structure in which multiple other electrodes face each other, and they can be electrically and mechanically connected and disconnected from each other. There may be.

[Embodiments of the invention] □ Examples of the present invention will be described below.

Example 1 This will be explained using FIG. Example 1 is an example of a plasma processing apparatus of the present invention using a conductive vacuum vessel 11. In the device of FIG. 1(a), S is placed on the lower electrode 13.
-i board 14 is attached.

After the inside of the vacuum vessel 11 was evacuated to about 5×10 −′ Torr, the upper electrode 12 with the protrusion 18 was lowered to integrate the upper and lower electrodes 12 and 13. The vacuum vessel 11, which is electrically isolated from these two electrodes 12, 13, is grounded.

Next, Ar gas is introduced from the gas inlet 10, the gas pressure is maintained at approximately 5X10-3 Torr, and the lower electrode is
．． Plasma was generated by applying a high frequency power of 56 MHz, IW/cJ, and after being maintained for about 10 minutes, the plasma was stopped and Ar exhaust was performed.
It was exhausted to Torr. This was approximately 20 minutes after the first evacuation started. In contrast, when the apparatus and method of the present invention are not used, it takes approximately 180 minutes to reach the same ultimate vacuum in an apparatus equipped with a vacuum evacuation system of the same performance. By implementing the substrate processing method of the present invention using the plasma processing apparatus of the present invention, the time required to evacuate the inside of the vacuum container was significantly shortened.

Example 2 Example 2 will be explained with reference to FIG. Example 2 is an example of a plasma processing apparatus of the present invention using a non-conductive vacuum vessel 21. In the device shown in FIG. 2, a Si substrate 24 is mounted on the lower electrode 23. After evacuating the inside of the vacuum container 21 to about 5X10-' Torr, the upper electrode 22 is lowered as in Example 1, and the upper and lower electrodes 22 and 23 are separated.
were integrated. Next, Ar gas was introduced from the gas inlet 20, the gas pressure was maintained at approximately 5×10 Torr, and the frequency of 13.56 MHz was maintained between the third electrode 29 (ground potential).

Plasma was generated by applying high frequency power of IW/cn. After maintaining the plasma for about 15 minutes, the plasma was stopped and the Ar gas was exhausted to about 1X10-'Torr in 10 minutes. In order to achieve this ultimate vacuum degree, which was obtained in about 30 minutes from the start of the first evacuation, without using the device of the present invention, it is necessary to
It took 0 minutes.

With this device, as in the case of Embodiment 1, true
,・The time required to clean the inside of an empty container has been significantly reduced.

Example 3 This will be explained using FIG. 1. Example 3 is an example in which the plasma processing apparatus and substrate processing method of the present invention are applied to the deposition of amorphous St on a St substrate by plasma vapor phase epitaxy. The inside of the vacuum vessel 11 was evacuated to 2.times.10-' Torr by the method described in Example 1, and the upper and lower electrodes 12 and 13 were separated by moving the upper electrode 12. After heating the Si substrate 14 to about 200° C., SiH+ gas is introduced from the gas inlet 10 at a flow rate of 100 cc/min, and a high frequency power of 13.56 MHz is applied IW/ct between the upper and lower electrodes 12 and 13. and generated plasma.

After holding for about 10 minutes, power application and introduction of SiH4 gas were stopped. Next, the vacuum chamber 11 was evacuated to 5×10 − ′ Torr, and then the inside of the vacuum chamber 11 was brought to atmospheric pressure by N2 leakage, and the Si substrate 14 was taken out. According to the Auger electron spectroscopy observation of the amorphous Si film deposited on the SL substrate, the peak intensity of O inside the film was the same as in Example 1.
If the method for cleaning inside the vacuum container is not used, that is,
Compared to the case where the amorphous St film was deposited immediately after evacuation to about 5×10-' Torr, which is the practical ultimate vacuum degree, the amount was reduced to about 20%. The plasma processing apparatus and substrate processing method of the present invention have the effect of significantly reducing the impurity content in the film and improving the film quality in depositing a material film by such plasma vapor phase epitaxy.

Example 4 This will be explained using FIG. 2. Example 4 is an example in which W was deposited by low pressure vapor phase epitaxy using the plasma processing apparatus of the present invention. After evacuating the inside of the vacuum container 21 to 1×10'' Torr by the method described in Example 2, the two electrodes 12 and 13 are separated, and then WF and gas are introduced from the gas inlet 20. W was deposited on the Si substrate 14 kept at about 450°C. From the results of Auger electron spectroscopy, the peak intensity of 0 inside the W film is
The amount was reduced to about 1/2 of that in the case where the vacuum container cleaning method of Example 2 was not used. The plasma processing apparatus and substrate processing method of the present invention reduce the amount of impurities in the deposited film and produce a high-quality film even in the low pressure vapor deposition method, as in the case of the plasma vapor deposition method in Example 3. It has the effect of enabling deposition.

In addition to the above embodiments, when the apparatus and method of the present invention are applied to etching processes such as reactive sputter etching, reactive ion beam etching, or plasma etching, multiple processing steps using different gases can be performed using the same apparatus. Even when etching is carried out, effects such as suppressing deterioration in etching controllability and reproducibility due to interaction between different gases and enabling highly accurate etching can also be obtained. Furthermore, in order to more easily clean the inside of the vacuum container, the same effect as in the above example can be obtained when plasma is generated by applying AC or DC power of 50 to 400 Hz instead of applying high frequency power. is obtained. Furthermore, in the above embodiment, only the case where a rare gas such as Ar is used as the substrate processing gas is described, but in addition to single reactive gases such as HQ, NQ, and OQ, CF4 can also be used as the substrate processing gas. It goes without saying that an appropriate gas is selected depending on the desired treatment, such as a compound of carbon with hydrogen or a halogen, or a hydrocarbon compound.

〔Effect of the invention〕

The plasma processing apparatus of the present invention can move all or at least one of the opposing electrodes housed in the vacuum container, so the plurality of electrodes can be integrated. It is possible to generate a plasma by applying electrical power between the integrated electrode and the conductive vacuum vessel or other electrodes within the vacuum vessel. At this time, the substrate attached to either of the integrated electrodes is not exposed to the plasma, so it will not be damaged by the plasma, and the inner wall of the vacuum chamber can be cleaned by ion bombardment without affecting the substrate. I can do it. As a result, compared to conventional equipment equipped with the same evacuation system, the time required to obtain the desired degree of vacuum inside the vacuum vessel is significantly shortened, and there is no need for large evacuation pumps or load lock mechanisms. However, even if the vacuum level is low, sufficient ultimate vacuum can be easily and inexpensively obtained.

Furthermore, prior to the desired substrate processing, the vacuum container and
By performing internal purification, it is possible to reduce the amount of impurities contained in the substrate processing gas, and to achieve high-quality film deposition, highly accurate etching, and effective substrate surface cleaning.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views of an embodiment of the plasma processing apparatus of the present invention. 101.・Gas inlet, 11... Conductive vacuum container, 1
2... Movable upper electrode, 13... Lower electrode opposite to the electrode 12, 14... Substrate, 15... Vacuum exhaust system, 16... High frequency power supply, 17A, B... Electrode applied power (b)

Claims (1)

[Claims] 1. At least two or more electrodes facing each other are housed in a vacuum container, and the plurality of electrodes includes one or more electrodes that can be insulated from the vacuum container, and the electrodes facing each other include one or more electrodes that can be insulated from the vacuum container. It is possible to electrically or mechanically connect the plurality of electrodes to each other by moving all or at least one electrode, and it is possible to apply electric power to at least one of the plurality of electrodes. A plasma processing device featuring: