JPS6379957A - Ion source - Google Patents

Abstract

PURPOSE:To simply clean plural electrodes for extracting ion beams without detaching an ion source by moving the electrodes having many small holes in a plane perpendicular to the direction in which the ion beams are extracted with an electrode moving device. CONSTITUTION:Gas G is introduced into an arc chamber 2 provided with a magnet 8 for confining plasma from the gas introducing hole 4, plasma is generated with a filament 6 and ion beams 20 are extracted from the plasma with an extracting electrode system consisting of an acceleration electrode 12, a deceleration electrode 13 and an earthing electrode 14 each having many small holes all over. An electrode moving device 24 or 26 is fitted to at least one electrode in the electrode system 10 so that the electrode can be moved in the directions of arrows A or B in a plane perpendicular to the direction in which the ion beams 20 are extracted. Thus, deposits on the electrodes 12-14 are sputtered with ion beams 20 to clean the electrodes.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an ion source used in, for example, an ion evaporation thin film forming apparatus or an ion beam etching apparatus that uses both vacuum thin deposition and ion beam irradiation, and particularly relates to an ion source that uses the ion beam irradiation. The present invention relates to cleaning means for extraction electrodes.

[Conventional technology]

An example of this type of ion source is shown in FIG. This ion source is a so-called brush type ion source, and gas G is introduced into the arc chamber 2 from the gas inlet 4 to cause arc discharge between the arc chamber 2, which also serves as an anode, and the filament 6. Plasma (not shown) is generated in the arc chamber 2, and the ion beam 20 is prevented from being extracted from this plasma by the action of an electric field using the extraction electrode system 10. 8 is a magnet for generating the magnetic field for plasma confinement.

In this example, the extraction electrode system 10 includes three electrodes arranged parallel to each other, each having a large number of small holes (see 12a, 13a, ], 4a in FIG. 3) on the negative side, that is, acceleration electrodes 12. , a deceleration electrode 13 and a ground electrode 14. A positive voltage is applied to the accelerating electrode 12 from an accelerating power source 16, a negative voltage is applied to the decelerating electrode 13 from a decelerating power source 18, and the grounding electrode 14 is grounded.

[Problem that the invention seeks to solve]

In the above-described ion source, when the ion source is kept open for a long time, ions are deposited on the surfaces of the deceleration electrode 13 and the ground electrode 14 facing the ion beam 20, as schematically shown in FIG. Due to divergence, collision, etc. of the beam 20,
Adhesive substance 22 made of a substance forming the ion beam 20
will be attached. For example, when the ion beam 20 is a silicon ion beam, silicon is deposited as the deposited substance 22 .

As a result, if the attached substance 22 is a conductive substance such as silicon or metal, the state of the electric field between each electrode 12 to 14 changes from the initial state, gradually affecting the uniformity of the ion beam 20, and Initial characteristics may not be obtained. Furthermore, the thin film layer made of such an attached substance 22 generally has a weak adhesion force and is easily peeled off, which may lead to breakdown between the electrodes 12 to 14. These troubles are particularly likely to occur when the spacing between the electrodes 12 to 14 is narrow.

Further, regardless of whether the adhered substance 22 is a conductive substance or not, the peeled thin film layer may become a contaminant for the object to be processed, such as a wafer.

To deal with this, there is an idea to remove the ion source from the other vacuum container (not shown) and clean the electrodes 13 and 14, but in that case, it is necessary to return the vacuum container to atmospheric pressure. Therefore, it takes a lot of time and effort.

Therefore, an object of the present invention is to provide an ion source whose electrodes can be cleaned without removing the ion source from a counterpart device.

[Means for solving problems]

The ion source of the present invention is characterized in that at least one electrode in the extraction electrode system is provided with an electrode moving device, thereby making the electrode movable in a plane perpendicular to the ion beam extraction direction.

[Effect]

By moving the electrodes in the extraction electrode system as described above, the ion beam can be actively applied to the electrode surface, thereby removing substances adhering to the electrode surface by the sputtering action of the ion beam. Electrodes can be cleaned.

〔Example〕

FIG. 1 is a sectional view showing an ion source according to an embodiment of the present invention. The same reference numerals are given to the same or corresponding parts as in FIG. 2, and the differences from the conventional example will be mainly explained below. Note that illustration of the power supplies 16 and 18 described above is omitted here.

In the ion source of this embodiment, electrode moving devices 24 and 26 are provided for the deceleration electrode 13 and the ground electrode 14, respectively. For example, they are made movable as shown by arrows A and B (see also FIG. 3).

The electrode moving devices 24 and 26 can be driven by manual,
Any motor-driven type can be used. Further, they may be located in a vacuum atmosphere, that is, in a vacuum container on the other side, or may be located in the atmosphere.

Even when placed in a vacuum atmosphere, the electrode 1 can be moved by a stamping motor that can be used in a vacuum.
3.14 can be positioned accurately.

In the above ion source, the ion beam 20 extracted from the accelerating electrode 12 is transferred to the decelerating electrode 13 by appropriately sliding the decelerating electrode 13 or the ground electrode 14.
Alternatively, the surface of the ground electrode 14 can be actively applied, whereby the adhered substances 22 adhering to the surfaces of both electrodes 13.14 are removed by the sputtering action of the ion beam 20, and the ground electrodes 13.14 are Can be cleaned.

For example, by slightly moving the decelerating electrode 13 in the direction of arrow A using the electrode moving device 24 and shifting the position of the small hole 13a of the decelerating electrode 13 and the position of the small hole 12a of the accelerating electrode 12, the ion beam 20
comes to hit the surface of the deceleration electrode 13. the result,
The adhering substance 22 adhering to the surface of the deceleration electrode 13 is removed by the sputtering effect of the ions. Thereafter, the deceleration electrode 13 is returned to its normal position. Cleaning of the ground electrode 14 can also be performed in the same manner as described above.

Therefore, according to the above-mentioned ion source, when cleaning the electrodes 13 and 14, there is no need to remove the ion source from the other vacuum container as in the conventional case. As a result, the downtime of the apparatus using the ion source is shortened, which in turn leads to an increase in the throughput of the apparatus.

In the above case, as the ion species of the ion beam 20 during cleaning, it is preferable to use inert gas ions such as argon, which have a good sputtering rate.

Further, the energy of the ion beam 20 during cleaning is preferably set to a value considerably lower than the energy during normal operation (for example, about several tens of KeV) from the viewpoint of minimizing the thermal load on the electrodes 13, 14 to be cleaned. .

For example, when comparing the case where the energy of the ion beam 20 is 20 KeV and the case where the energy is IKeV, if the beam current is constant, the power of the ion beam 20 is
．． In the latter case, the heat load on 14 is reduced to 1/20 of the former. On the other hand, when the deposited material 22 is silicon and the ion species is argon, the sputtering rate is 2 and 0.8 when the energy of the ion beam 20 is 20 KeV and IKeV, respectively. In the latter case, the removal rate of No. 22 is reduced to only 1/2.5 of the former. Therefore, the energy of the ion beam 20 during cleaning is preferably about IKeV or less, for example.

Adhesive substances 2 adhering to the deceleration electrode 13 and the ground electrode 14
2, the completion of cleaning is determined by, for example, mass spectrometry or emission spectroscopy, etc., to determine the specific substance (for example, the substance constituting the adhered substance 22) in the atmosphere during cleaning.
This can also be done by detecting temporal changes in
In this case, since very strictness is not required, simply managing the cleaning time can suffice to achieve the purpose.

In the above embodiment, the deceleration electrode 13 and the ground electrode 14 are slid from the viewpoint of easy electrical insulation, but the point is that the acceleration electrode 13 and the ground electrode 14 are slid in the direction perpendicular to the direction in which the ion beam 20 is extracted. The relative positional relationship (alignment) of the decelerating electrode 13 and the grounding electrode 14 with respect to the accelerating electrode 12 may be smoothed.
Of course, the deceleration electrode 13 or the ground electrode 14 may be slid.

Further, the extraction electrode system 10 includes an acceleration electrode 12 and a deceleration electrode 13.
(or ground electrode 14), the deceleration electrode 13 (or ground electrode 14) should be slid, or the acceleration electrode 12 should be slid, using the same idea as above. Also good.

〔Effect of the invention〕

As described above, according to the ion source of the present invention, the electrode can be cleaned without removing it from the other device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an ion source according to one embodiment of the present invention. FIG. 2 is a sectional view showing an example of a conventional ion source. FIG. 3 is an enlarged and partially sectional view of the extraction electrode system shown in FIG. 2. FIG. 10... Extraction electrode system, 12... Acceleration electrode, 13.
... Deceleration electrode, 14... Ground electrode, 12a, 13a,
14a...Small hole, 2o...Ion beam, 22...
- Adhesive substance, 24.26...electrode moving device.

Claims (1)

[Claims] (1) In an ion source in which a plurality of electrodes each having a large number of small holes on one side are arranged in parallel to each other to constitute an extraction electrode system for extracting an ion beam, at least one electrode in the extraction electrode system An electrode moving device is installed in the
An ion source characterized in that the electrode is thereby movable in a plane perpendicular to the ion beam extraction direction.