JPH04315797A - Plasme processing device and method of cleaning plasma source thereof - Google Patents

Abstract

PURPOSE:To extremely easily perform the cleaning inside a plasma generation vessel by applying a voltage to the vessel with a plasma being generated inside the plasma generation vessel of a source. CONSTITUTION:With a plasma generation vessel 4 being electrically floated from a vacuum vessel 20 by an insulator 24, a plasma 18 is generated in the plasma generation vessel 4, and when an appropriate voltage according to the kind of gas 8 (that is a positive or a negative DC voltage and a high frequency voltage if necessary) is applied to the plasma generation vessel 4 from a cleaning power supply 26, ions in the plasma 18 removes contaminants sticking to the inner wall of the plasma generation vessel 4 by means of the voltage so that cleaning is performed. The removed contaminants are removed, since the vacuum vessel 20 has been evacuated. Thus, the cleaning of the inner wall of the plasma formation vessel 4 can be extremely easily performed without decomposing a plasma source 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus that performs etching, thin film formation, etc. on a workpiece using plasma, and a method of cleaning the plasma source thereof.

0002

2. Description of the Related Art A conventional example of this type of plasma processing apparatus is shown in FIG.

[0003] This plasma processing apparatus includes a plasma source 2 and a vacuum vessel 20 connected to it.

The plasma source 2 has a plasma generation vessel 4 in which a plasma 18 is generated, which includes a required gas 8 from a gas introduction tube 6 and a microwave introduction window from a microwave waveguide 10. Microwave 1 through 12
4 will be introduced.

Further, in this example, a cylindrical member is provided on the outer periphery of the plasma generation container 4 to generate a magnetic field that satisfies ECR (electron cyclotron resonance) conditions in a direction along the introduction direction of the microwave 14 inside the container 4. magnetic coil 16
is provided.

[0006] A holder 21 is provided inside the vacuum container 20, and an object to be processed (eg, a substrate or a wafer) 22 is mounted on the holder 21. Further, the inside of this vacuum container 20 and the plasma generation container 4 connected thereto are evacuated by a vacuum evacuation device (not shown).

In the above plasma processing apparatus, when the vacuum chamber 20 is evacuated and the gas 8 and the microwave 14 are introduced into the plasma generation chamber 4 of the plasma source 2, the gas 8 is excited by the microwave 14 and a plasma is generated. A plasma 18 is created within the generation vessel 4 . The plasma 18 created in this way diffuses into the vacuum container 20,
This plasma 18 allows processing such as etching and film formation to be performed on the object 22 to be processed.

[0008]

[Problems to be Solved by the Invention] Dust adheres to the inner wall of the plasma generation container 4 of the plasma source 2 during operation, but if this is left unattended, the dust may peel off during operation. Particles are generated and adhere to the surface of the object to be processed 22, causing various problems such as contamination of the film with impurities and device defects.

In order to prevent this, conventionally, the plasma source 2
It is necessary to disassemble the plasma generation container 4 and clean the inner wall of the plasma generation container 4 with a solvent or mechanically (for example, with sandpaper), and this cleaning has to be performed frequently, which is very time-consuming. Ta.

Therefore, the main object of the present invention is to make it possible to easily clean the inner wall of the plasma generation container of the plasma source as described above.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the plasma processing apparatus of the present invention includes an insulating material between the plasma generation container of the plasma source and the vacuum container to electrically insulate the two. and a power source for applying a voltage to the plasma generation vessel to attract ions in the plasma generated therein.

Further, in the cleaning method of the present invention, plasma is generated in the plasma generation container in a state where the plasma generation container for generating plasma of the plasma source is electrically insulated from the other vacuum container, and the plasma is generated in the plasma generation container. It is characterized by applying a voltage to the generation vessel to attract ions in the plasma generated therein.

[0013]

[Function] According to the above plasma processing apparatus, plasma is generated in the plasma generation container while the plasma generation container of the plasma source is electrically suspended from the vacuum container by the insulator, and voltage is applied to the plasma generation container from the power supply. When the voltage is applied, ions in the plasma are drawn toward the plasma generation container by this voltage, and dust can be removed and cleaned from the inner wall of the plasma generation container by sputtering or the like by these ions. In the case of the above-mentioned cleaning method, it is also possible to clean the inner wall of the plasma generation container by removing dust by sputtering using ions or the like.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic sectional view showing a plasma processing apparatus according to an embodiment of the present invention. The same reference numerals are given to the same or corresponding parts as in the conventional example shown in FIG. 2, and the differences from the conventional example will be mainly explained below.

In this embodiment, an insulator 24 is provided between the plasma generation vessel 4 of the plasma source 2 and the vacuum vessel 20 as described above to electrically insulate the two. The insulator 24 may be, for example, a packing such as a rectangular ring, or may be a combination of another insulator and a packing such as an O-ring.

Further, a cleaning power supply 26 is connected between the plasma generation vessel 4 and the ground, which outputs a voltage that draws ions in the plasma 18 generated within the plasma generation vessel 4 to the vessel 4 . In this embodiment, the cleaning power supply 26 includes a high frequency power supply 27 that applies a high frequency voltage to the plasma generation vessel 4, a variable voltage DC power supply 30 that applies a positive DC voltage to the plasma generation vessel 4, and a negative voltage power supply 30 that applies a positive DC voltage to the plasma generation vessel 4. A variable voltage DC power supply 32 is provided to apply a DC voltage of . A matching box 28 is inserted in series with the high-frequency power source 27, and includes a blocking capacitor (not shown) for blocking direct current. A blocking coil 34 for blocking high frequencies is inserted in series with the DC power supplies 30 and 32.

The reason why both the positive and negative DC power supplies 30 and 32 are provided is that depending on the gas 8 used, the ions in the plasma 18 may become positive ions or negative ions, and it is possible to deal with either of them. This is to make it possible. For example, when an inert gas such as argon is used as the gas 8, positive ions are generated in the plasma 18, so a negative voltage is applied to the plasma generation vessel 4 using the DC power supply 32 side. Further, when using a halogen gas such as chlorine as the gas 8, negative ions are generated in the plasma 18, so the DC power supply 30 side is used to generate the plasma generation vessel 4.
Apply positive voltage to .

Furthermore, the high frequency power source 27 is provided because:
This is to prevent the inflow of ions from being stopped due to charging caused by the ions flowing into the dust when the dust adhering to the inner wall of the plasma generation container 4 is insulating. That is, when a high frequency voltage is applied to the plasma generation container 4, the electrons in the plasma 18 are attracted to the plasma generation container 4 side during the negative cycle, and this neutralizes the positive charge, thereby reducing the charging of insulating dust. This makes it possible to effectively attract ions using the DC voltage.

[0019] Therefore, if either positive ions or negative ions are generated, the DC power source may be either one of them. Furthermore, if the dust adhering to the inner wall of the plasma generation container 4 is limited to conductive materials,
The high frequency power source 27 does not necessarily need to be provided.

[0020] Furthermore, the plasma generation vessel 4 and the vacuum vessel 20
Even if you install something like a switch between the two, turn it on during normal operation to electrically connect the two, and turn it off during cleaning to electrically isolate the two. good.

[0021] The plasma generation container 4 can be cleaned in the following manner using such an apparatus. That is, while the plasma generation vessel 4 is electrically suspended from the vacuum vessel 20 by the insulator 24, the plasma 18 is generated in the plasma generation vessel 4 as described above, and the cleaning power supply 26 is supplied to the plasma generation vessel 4. When an appropriate voltage depending on the type of gas 8 is applied (i.e., a positive or negative DC voltage as described above and a high frequency voltage if necessary), ions in the plasma 18 are moved toward the plasma generation container 4 side by this voltage. The dust adhering to the inner wall of the plasma generation container 4 can be removed and cleaned by sputtering by the ions and a chemical reaction between the ions and the dust. The removed garbage is placed in vacuum container 2.
Since the inside of 0 is exhausted, it is discharged to the outside. Therefore,
Unlike the conventional example, there is no need to disassemble the plasma source 2, and the inner wall of the plasma generation container 4 can be cleaned extremely easily.

Next, the results obtained when the object 22 to be processed is etched under the following conditions will be explained. Gas used: Cl2 (flow rate 20 cc/min) Introduced microwave power: 1 KW Vacuum degree in vacuum container: 5 x 10-4 Torr Object to be processed:
Al alloy film (thickness: 1 μm) In such a case, with the conventional apparatus, if the plasma generation container 4 is not cleaned (mechanical cleaning) every time about 100 objects 22 are processed, the film will be removed from the wall surface. It peeled off and particles were generated. Furthermore, it took about one day to mechanically clean the plasma generation container 4 once.

On the other hand, in the configuration shown in FIG.
The inner wall of the plasma generation container was cleaned by plasma 18 for 2 hours every time 500 sheets were processed. Now, mechanical cleaning only needs to be performed every time about 2,000 sheets are processed. That is, the period of mechanical cleaning could be extended by about 20 times compared to the conventional method.

Note that the type of plasma source 2 is not limited to the ECR type as in the above example, but may be of other types, for example, having a filament in the plasma generation vessel 4 and generating the gas 8 by arc discharge or the like. It may be of a type that excites.

[0025] The gas 8 used is also C as in the above example.
The gas is not limited to l2, and other gases such as SF6, NF3, etc. may be used.

[0026] Furthermore, the plasma processing apparatus as described above has the following features:
Of course, it can also be used for forming thin films other than etching.

[0027]

As described above, in the plasma processing apparatus of the present invention, the inner wall of the plasma generation container of the plasma source can be cleaned by applying a voltage to the plasma generation container while generating plasma in the container. Since the cleaning can be performed using the plasma inside the plasma source, there is no need to disassemble the plasma source, and therefore the inner wall of the plasma generation container can be cleaned extremely easily. By performing such cleaning, the period of cleaning and mechanical cleaning of the plasma generation container can be significantly extended.

Similarly, according to the cleaning method of the present invention, the inner wall of the plasma generation container of the plasma source can be cleaned using the plasma generated inside the plasma source, so there is no need to disassemble the plasma source, and therefore the plasma generation chamber can be cleaned. The inner wall of the container can be cleaned extremely easily. By performing such cleaning, the period of cleaning and mechanical cleaning of the plasma generation container can be significantly extended.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of a conventional plasma processing apparatus.

[Explanation of symbols]

2 Plasma source 4 Plasma generation container 18 Plasma 20 Vacuum container 22 Object to be treated 24 Insulator 26 Cleaning power supply

Claims (2)

[Claims] Claim 1: A plasma source that has a plasma generation vessel and generates plasma therein; and a plasma source that is connected to the plasma source and that processes a workpiece using the plasma generated by the plasma source. In a plasma processing apparatus comprising a vacuum vessel, an insulator is provided between the plasma generation vessel of the plasma source and the vacuum vessel to electrically insulate them, and the plasma generated therein is provided in the plasma generation vessel. A plasma processing apparatus characterized by being equipped with a power source that applies a voltage that attracts ions therein. [Claim 2] Plasma is generated in the plasma generation container in a state where the plasma generation container that generates the plasma of the plasma source is electrically insulated from the other side vacuum container, and the plasma generation container is heated inside the plasma generation container. A plasma source cleaning method characterized by applying a voltage that attracts ions in the generated plasma.