JPH0740469B2 - Ion source device and operating method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ion source device and an operating method thereof, and particularly to a reactive ion beam for finely processing a surface of a workpiece by utilizing chemical reaction and sputtering. The present invention relates to an ion source device suitable for an etching device and an operating method thereof.

[Conventional technology]

In general, an ion source device, particularly a high-power ion source device, causes various discharges such as glow discharge, arc discharge, and high frequency discharge in a low-pressure discharge chamber, and the discharge causes the gas in the discharge chamber to become plasma. It is configured to extract ions.

By the way, in such an ion source device, a device in which a cusp magnetic field is formed in the discharge chamber in order to generate plasma having high spatial uniformity is disclosed in, for example, Japanese Patent Laid-Open No.
It is disclosed in Japanese Patent Laid-Open No. 79900, Japanese Patent Laid-Open No. 57-185653, and the like.

[Problems to be Solved by the Invention]

However, when a compound gas (fluorine, chlorine compound, etc.) is ionized by the ion source device using the cusp magnetic field described above to generate plasma, a precipitate due to the plasma polymerization reaction of the compound gas, that is, a high molecular weight insulating property is generated. It was found that the substance does not discharge because it adheres to and deposits on the wall surface of the plasma generating container that is the anode. In other words, since the plasma generation container is an anode that is the positive electrode of DC arc discharge, if the above products adhere to this anode, the discharge becomes unstable or does not stop, and these are the basic operations of the ion source. However, there is a risk that stable discharge cannot be maintained for the compound gas.

The present invention has been made in view of the above points, and an object of the present invention is that even if a compound gas is ionized to generate plasma, discharge is not unstable or does not stop. Another object of the present invention is to provide an ion source device capable of maintaining stable discharge with respect to a compound gas, and an operating method of an ion source device capable of continuing stable discharge even at the beginning of operation.

[Means for Solving the Problems]

The present invention provides an anode electrode with a predetermined gap from the inner wall of the plasma chamber to form plasma by ionizing the compound gas by the discharge between the cathode and the anode, or generates a discharge between the cathode and the cathode. A non-magnetic material for the purpose of providing a non-magnetic material with a certain gap between the inner wall of the plasma and the ion source device, and at the beginning of operation by energizing the ion source, plasma was created with argon gas, hydrogen or gas and installed as described above. The anode is preheated to a high temperature, then switched to a compound gas, the compound gas is turned into plasma, and the ion source device is taken out from the plasma.

[Action]

According to the ion source device of the present invention, inside the plasma chamber,
The anode electrode or the non-magnetic material provided with a predetermined gap from the plasma chamber inner wall is separated from the plasma chamber inner wall and is not thermally cooled, and is accelerated between the anode electrode or the non-magnetic material and the plasma. Since the electrons flow in and are heated to a high temperature, the insulating polymer material generated by the discharge of the compound gas does not adhere to the anode electrode or the non-magnetic material, and the above object is achieved. It

According to the method of operating the ion source device of the present invention, at the beginning of energizing the ion source to start the operation, plasma is generated by argon gas or hydrogen gas to preheat the anode electrode to a high temperature, and then the compound gas is used. Since it is switched to, stable discharge can be maintained even at the beginning of operation.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments of the drawings.

FIG. 1 shows an embodiment of the ion source device of the present invention.

As shown in the figure, a normal ion source device also serves as an anode,
And, a substantially cylindrical plasma generation container 2A having a plurality of permanent magnets 7A on the outer periphery thereof, and forming a part of this plasma generation container 2A, and having a plurality of permanent magnets 7B on the outer periphery thereof, CF ₄ , or A plasma generation container upper lid 2B having a gas inlet 1 for introducing a gas containing a compound gas such as a mixed gas of CF ₄ and Ar, and a plasma generation container 2A supported on the central axis of the plasma generation container 2A. Cathode 3 that uses a hairpin-shaped tungsten filament arranged in the center, and extraction electrodes 5 and 6 with a large number of small holes that extract ions from the formed plasma and irradiate the workpiece as an ion beam as shown by the arrows. It is composed of and. The plurality of permanent magnets 7A, 7B described above are provided along the outer circumference of the container so that the N pole and the S pole face the central axis of the cylinder.
A line cusp magnetic field is created inside the container. Further, a water cooling pipe 8 is installed between the rows of the permanent magnets 7A and 7B to prevent the performance of the permanent magnets 7A and 7B from being deteriorated due to the temperature rise. In the present embodiment, the anode electrode 4 is provided on the inner circumference of the plasma generating container 2A via the magnetic material 9 so as to maintain a predetermined gap with the inner wall of the plasma generating container 2A. The anode electrode 4 is made of non-magnetic stainless steel with a plate thickness of 0.5 mm, and has a structure in which a cylinder with a length of 150 mm is halved in the direction along the central axis. The plasma generation container is attached and supported by welding, and the other end of the magnetic material 9 is attracted by the permanent magnet 7A.
It is held and fixed inside 2A.

In such a configuration, by introducing a gas containing a compound gas such as a mixed gas of CF ₄ or CF ₄ and Ar, the gas inlet 1, a DC voltage is applied to the cathode 3 and the anode electrode 4 made of tungsten filament, Plasma is generated by ionizing the gas by the thermoelectrons of the cathode 3. An ion beam is extracted from this plasma by the extraction electrodes 5 and 6, and the workpiece is irradiated with the ion beam.

Therefore, as described above, if the anode electrode 4 is provided inside the plasma generation container 2A, the anode electrode 4 is not electrically cooled because it is electrically connected to the plasma generation container 2A, and the anode electrode 4 is not cooled. 4 and the plasma are accelerated and flow in, so that the plasma is heated.
Works at much higher temperatures. Therefore, the anode electrode 4
Does not adhere to the insulating polymer substance generated by the discharge of the compound gas, and the discharge becomes unstable or does not stop. There is no problem, and stable discharge can be maintained even for compound gas. Further, since the anode electrode 4 is fixed by utilizing magnetism, maintenance work such as replacement and cleaning of the anode electrode 4 itself is easy, and when a part of the magnetic material 9 supporting the anode electrode 4 is insulated. A potential different from that of the plasma generation container 2A can be applied to the anode electrode 4, and there is an effect that confinement of electrons or ions can be improved.

Furthermore, since the anode electrode 4 is at room temperature at the beginning when the ion source is energized to start the operation, there is a possibility that an insulating polymer product produced by plasma may be attached and the discharge may become unstable. At the beginning of the operation, plasma is generated by Ar gas or H ₂ gas to preheat the anode electrode 4 to a high temperature, and then stable discharge can be continued by switching to compound gas such as CF ₄ . If the anode electrode 4 is provided with a temperature sensor such as a thermocouple, the temperature of the anode electrode 4 can be known. In this embodiment, this temperature sensor is used for the anode electrode 4
It was confirmed that stable discharge was possible when the temperature was above 150 ℃ -200 ℃. Further, by keeping the anode electrode 4 at a high temperature, it is possible to prevent the deposition of the insulating polymer product, but since low molecular weight solids such as carbon are deposited,
It is necessary to frequently perform maintenance work such as replacement and cleaning of the anode electrode 4. At this time, if hydrogen plasma is used,
Polymers such as fluorine and chlorine deposited on the anode electrode 4 are decomposed by the reducing action of the hydrogen ions, so that fluorine or the like contained in carbon is discharged as a volatile component out of the system by a vacuum pump. At the same time that stable discharge is restored, maintenance work such as replacement and cleaning of the anode electrode 4 becomes less complicated.

Next, FIG. 2 and FIG. 3 show other embodiments of the present invention.

In the embodiment shown in FIG. 2, instead of the above-mentioned tungsten filament as the cathode, electrons, hollow cathode, etc. extracted from plasma by electrodeless discharge such as high-frequency plasma or microwave plasma are used.

Therefore, in the example shown in FIG. 2, the plasma generation container upper lid 2B having the permanent magnet 7B is provided with the gas introduction port 10b and the glass tube 10a having the RF coil 11 around the electron extraction electrode 12, It is provided via the insulating spacer 13 and serves as a source of electrons. The other structure is the same as that of the embodiment shown in FIG.

With such a configuration, stable discharge can be maintained, and since there is no filament, maintenance work for filament replacement can be omitted.

Next, in the embodiment shown in FIG. 3, the work piece 15 is placed at the positions of the extraction electrodes 5 and 6 in the ion source device having the construction shown in FIG. 1, and the work piece 15 is directly exposed to plasma. As a result, etching can be performed, and the same effects as those in FIG. 1 can be obtained, and of course, the damage to the work piece due to the ion beam impact can be reduced.

〔The invention's effect〕

According to the ion source device of the present invention and the method of operating the same described above, a non-magnetic material that causes discharge between the anode electrode or the cathode is provided on the inner circumference of the plasma generation container having a plurality of permanent magnets on the outer circumference. Since it is provided with a predetermined gap with the inner wall of the plasma generation container, the anode electrode or the non-magnetic material can be kept at a high temperature.
The insulating polymer product does not adhere to the anode electrode or the non-magnetic material, destabilization of discharge can be prevented, and stable discharge can be maintained even for compound gas. In addition, at the beginning of the operation, a plasma is created with Ar and gas or H ₂ gas to preheat the anode to a high temperature, and then a predetermined operation is performed by switching to the compound gas. Stable operation can be maintained. Therefore, it is very effective for this type of ion source device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of the ion source device of the present invention, and FIGS. 2 and 3 are sectional views showing other embodiments of the present invention. 1,10b …… Gas inlet, 2A …… Plasma generator, 2B…
… Plasma generator container top cover, 3… Cathode, 4… Anode electrode, 5,6… Extraction electrode, 7A, 7B… Permanent magnet,
8: Water cooling pipe, 9: Magnetic material, 10a: Glass tube, 1
1 ... RF coil, 12 ... Electron extraction electrode, 13 ... Insulating spacer, 15 ... Workpiece.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinya Sekimoto 1-1-1 Kokubun-cho, Hitachi City, Ibaraki Inside the Kokubun Plant of Hitachi, Ltd. (56) Reference JP-A-57-90900 (JP, A)

Claims (11)

[Claims] 1. An ion source device for ionizing a compound gas to generate a plasma by discharging between a cathode and an anode in a plasma chamber having a plurality of permanent magnets on the outer periphery thereof, wherein an inner wall of the plasma chamber is formed on the inner periphery of the plasma chamber. An ion source device comprising an anode electrode supported with a predetermined gap. 2. The ion source device according to claim 1, wherein the anode electrode is fixed to the inner circumference of the plasma chamber via a magnetic material. 3. The ion source device according to claim 2, wherein a part of the magnetic material is insulated. 4. The ion source device according to claim 2 or 3, wherein the magnetic material is attracted by the permanent magnet and held in the plasma chamber. 5. The ion source device according to claim 1, wherein the cathode comprises a filament provided in a plasma chamber. 6. The ion source device according to claim 1, wherein a plasma generated by a high frequency electrodeless discharge such as a high frequency plasma source or a microwave plasma source is used as the cathode. 7. A plurality of extraction electrodes for extracting an ion beam from plasma produced by ionizing a compound gas by discharge between the cathode and the anode, and processing the ion beam extracted by the extraction electrodes. The ion source device according to claim 1, which irradiates an object. 8. The ion source device according to claim 1, wherein the workpiece is irradiated with plasma generated by ionizing a compound gas by discharge between the cathode and the anode. 9. An ion source device for producing a plasma by ionizing a compound gas by a discharge between a cathode and an anode in a plasma chamber having a plurality of permanent magnets on the outer circumference, and using a plasma of a non-stationary discharge as the cathode, An ion source device, wherein an electrode as an anode is provided on the inner circumference of the plasma chamber with a predetermined gap from the inner wall of the plasma chamber. 10. An ion source device for producing a plasma by ionizing a compound gas by a discharge between a cathode and an anode in a plasma chamber having a plurality of permanent magnets on the outer circumference, and an ion source device on the inner circumference of the plasma chamber between the cathode and the cathode. An ion source device characterized in that a non-magnetic material for causing an electric discharge is provided with a predetermined gap from an inner wall of a plasma chamber. 11. A method for operating an ion source apparatus, wherein a discharge is generated between a cathode and an anode in a plasma chamber, the compound gas in the plasma chamber is turned into plasma by this discharge, and ions are taken out from the plasma. At the beginning of the operation, a plasma is created with argon gas or hydrogen gas, and the plasma is used to preheat the anode supported by a predetermined gap in the inner periphery of the plasma chamber to a high temperature. The method of operating an ion source device, comprising: