JPH0720837Y2 - Ion source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an ion source in which an electrode interval can be adjusted from the outside.

[Conventional technology]

FIG. 3 is a schematic sectional view showing an example of an ion treatment apparatus using a conventional ion source. The target 34 to be processed is housed in the vacuum container 30, and the ion source 2 is attached to the upper part thereof. The ion source 2 has an arc chamber 8 for generating plasma and an extraction electrode system for extracting the ion beam 28 from the arc chamber 8.

In this example, the extraction electrode system is composed of three electrodes arranged in parallel with each other, that is, an acceleration electrode 18 for drawing out the ion beam 28 that is made to have a positive potential and a deceleration that repels electrons from a downstream of the ion beam when made to have a negative potential. It consists of an electrode 20 and a ground electrode 22 which is brought to ground potential. Each electrode 18, 20, 22 has a large number of through holes for extracting the ion beam 28. The acceleration electrode 18 is fixed to the flange 12, the deceleration electrode 20 is fixed to the support 26 via the insulating spacer 24, and the ground electrode 22 is directly fixed to the support 26. The support 26 is the ion source 2
Is fixed to a flange 16 for attaching to the vacuum container 30 or the like.

In the figure, 4 is a gas inlet for introducing the gas G as an ionized substance into the arc chamber 8, 6 is a filament, and 10 and 14 are insulating spacers.

Explaining an example of the operation, the inside of the vacuum container 30 and the like is kept in a vacuum state by a vacuum pump (not shown) through the exhaust port 32, and then a minute gas G is supplied from the gas inlet 4 into the arc chamber 8. To do. Then, an electric current is applied to the filament 6 to heat the filament 6 to emit thermoelectrons,
A voltage of, for example, about several tens of volts is applied to the arc chamber 8 to cause arc discharge between the filament 6 and the arc chamber 8 to turn the introduced gas G into plasma,
Generate the required ions. Then, a high voltage (acceleration voltage) of, for example, about several tens of KV is applied between the acceleration electrode 18 and the deceleration electrode 20 (or the ground electrode 22) to extract the ion beam 28, which is irradiated to the target 34 to irradiate the target 34. Process (for example, ion implantation, etching, etc.).

[Problems to be solved by the invention]

In the ion source 2 as described above, when the accelerating voltage described above is changed, the accelerating electric field of the ion beam 28 is changed because the electrode distance L between the accelerating electrode 18 and the deceleration voltage 20 is constant, which causes The beam current of the ion beam 28 changes (for example, when the acceleration voltage is increased, the beam current also increases, and when the acceleration voltage is decreased, the beam current also decreases), the divergence angle of the ion beam 28 changes, and the target 34 There is a problem that the beam current obtained above changes.

To prevent this, conventionally, when changing the accelerating voltage, the ion source 2 is disassembled and a spacer is inserted between the accelerating electrode 18 and the flange 12 or between the support 26 and the flange 16. Although the electrode distance L is adjusted, a large amount of loss time is generated for that reason.

Therefore, the main object of the present invention is to provide an ion source in which the electrode spacing L as described above can be adjusted from the outside.

[Means for solving problems]

This invention relates to an ion source having a plurality of electrodes arranged in parallel with each other, each of which has a large number of through holes for extracting ions, and has a positive potential on the most upstream side of the ion beam among the electrodes. The fixed electrode is attached, and the remaining electrode is attached to the electrode drive mechanism that linearly drives it externally while keeping parallel to the positive potential electrode, and the positive potential electrode and the remaining electrode The electrode spacing between the electrodes is adjustable from the outside, and this electrode drive mechanism has a mounting plate to which the remaining electrodes are mounted and a slide type bearing to guide the linear movement of the mounting plate. 1 or more guide shaft portions, a ball screw for linearly driving the mounting plate from the outside in a vacuum-sealed state, and a drive portion for rotationally driving the shaft of the ball screw from the outside.

[Action]

The electrode driving mechanism externally adjusts the electrode spacing between the electrode that is set to a positive potential and the remaining electrodes. This makes it possible to make the electrode interval according to the acceleration voltage.

〔Example〕

1 is a schematic sectional view showing an example of an ion treatment apparatus using an ion source according to an embodiment of the present invention, and FIG. 2 is a plan view partially showing the electrode driving mechanism of FIG. . The same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In the ion source 36 according to this embodiment, the ion beam
While the accelerating electrode 18, which is on the most upstream side of 28 and is set to a positive potential, is fixed to the flange 12, the electrode driving mechanism 38 keeps the deceleration electrode 20 and the ground electrode 22 parallel to the accelerating electrode 18. It can be linearly driven as indicated by an arrow A so that the electrode distance L between the acceleration electrode 18 and the deceleration electrode 20 can be adjusted from the outside of the ion source 36 (that is, the atmosphere side). ing.

More specifically, in this example, the electrode driving mechanism 38 includes a mounting plate 40 to which a support body 26 that supports the deceleration electrode 20 and the ground electrode 22 is mounted, and two (first) mounting plates 40 that guide the linear movement of the mounting plate 40. (See Fig. 2) Ball shaft 48 for linear drive with the guide shaft 42 and mounting plate 40 vacuum-sealed from the outside.
And a drive unit 54 that rotationally drives the shaft 52 of the ball screw 48.

The guide shaft portion 42 has a bearing (slide type bearing) 44 mounted on the mounting plate 40, a shaft 46 penetrating the bearing 44 and having one end fixed to the flange 16, and a ball screw 48.
Has a bearing 50 attached to the attachment plate 40 and a shaft 52 penetrating the bearing 50 and having a drive portion 54 attached to one end on the atmosphere side. The portion where the shaft 52 penetrates the flange 16 is vacuum-sealed, although not shown. For the drive unit 54, for example, a manual handle or a pulse motor can be used.

Incidentally, reference numerals 19, 21 and 23 in the figure are a large number of through holes for extracting the ion beam 28, which are provided at positions corresponding to the acceleration electrode 18, the deceleration electrode 20 and the ground electrode 22, respectively.

To explain the operation, the shaft of the ball screw 48 is driven by the drive unit 54.
When 52 is rotated (normal rotation or reverse rotation), the attachment plate 40, that is, the deceleration electrode 20 and the ground electrode 22 attached to the attachment plate 40 move up and down as shown by arrow A. In that case, since the guide shaft portion 42 is provided, the mounting plate 40 does not rotate or tilt, and the deceleration electrode 20 and the ground electrode 22 are linearly driven while maintaining the initial parallel relationship with the acceleration electrode 18. Electrode spacing L
Is adjusted.

As described above, in the ion source 36, the electrode distance L can be freely adjusted from the outside between the acceleration electrode 18 and the deceleration electrode 20 while keeping the two electrodes parallel to each other. That is, the accelerating electric field of the ion beam 28 can be made constant even if the accelerating voltage is changed. As a result, a stable ion beam 28, that is, an ion beam 28 having a stable output beam current and divergence angle can be obtained even when the accelerating voltage is changed.

Moreover, in this ion source 36, the deceleration electrode on the low potential side
Since the electrode 20 and the ground electrode 22 are driven to adjust the electrode interval L, the electrical insulation around the electrode drive mechanism 38 is easy unlike the case where the acceleration electrode 18 on the high potential side is driven.

Further, in this embodiment, since the bearing 44 is used for the guide shaft portion 42, the deceleration electrode 20 and the ground electrode 22 move smoothly. Also, although the guide shaft portion 42 may be provided at only one place, in this example, it is provided at two places, so
Also, there is almost no problem such as displacement or inclination of the ground electrode 22. Further, the bearing 44 and the shaft 46 may be fitted to each other, which makes it possible to completely eliminate the inclination of the deceleration electrode 20 and the ground electrode 22. Also, because the ball screw 48 is used, the reduction electrode 20 and the ground electrode 22
The precision of the movement of is very accurate, and it is also possible to express the distance moved by the deceleration electrode 20 and the ground electrode 22 and the electrode interval L by the rotation speed of the shaft 52.

Depending on the ion source, there may be two types of electrodes, that is, the acceleration electrode 18 and either the deceleration electrode 20 or the ground electrode 22, but even in that case, the structure as described above can be applied. Needless to say. Although the bucket source type ion source by arc discharge using the filament 6 is exemplified as the ion source 36 in the above, the present invention proposes an ECR type ion source by microwave discharge and further a plurality of electrodes for extracting ions. It can be widely applied to all ion sources having.

[Effect of device]

As described above, according to the present invention, the electrode interval can be adjusted from the outside, and thus a stable ion beam can be obtained even when the accelerating voltage is changed.

Moreover, by using the electrode driving mechanism as described above, it is possible to prevent the mounting plate from rotating or tilting by one or more guide shaft portions and accurately guide the movable electrode. The parallelism between the fixed-side and movable-side electrodes and the positional relationship between the through-holes of the fixed-side and movable-side electrodes can be accurately maintained even if the electrode interval is changed.

In addition, since the slide shaft bearing is used for the guide shaft, there is little friction in the guide shaft when the electrode moves, so even a large diameter and heavy electrode can be moved lightly and smoothly with a small ball screw. It can be done, and the drive unit can be small.

In addition, the ball screw is used to convert the rotational movement into a linear movement, and the ball screw has balls in the threaded portion as is well known, so the backlash is very small, and therefore the electrode spacing is accurate. And, it can be adjusted from the outside with good reproducibility.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an ion treatment apparatus using an ion source according to an embodiment of the present invention. FIG. 2 is a plan view partially showing the electrode driving mechanism of FIG. FIG. 3 is a schematic sectional view showing an example of an ion treatment apparatus using a conventional ion source. 8 ... Arc chamber, 18 ... Accelerating electrode, 20 ... Decelerating electrode, 22 ... Ground electrode, 28 ... Ion beam, 30 ... Vacuum container, 34 ... Target, 38 ... Electrode drive mechanism, 40 ...
… Mounting plate, 42 …… Guide shaft, 48 …… Ball screw, 54…
… Drive unit, L… Electrode spacing

Claims (1)

[Scope of utility model registration request] 1. An ion source comprising a plurality of electrodes, each of which has a large number of through holes for extracting ions and which are arranged in parallel with each other, in which the positive electrode is located on the most upstream side of the ion beam. The electrodes that are set to the potential are fixed, and the remaining electrodes are attached to an electrode drive mechanism that linearly drives them from the outside while keeping the electrodes parallel to the electrodes that are set to the positive potential. And the electrode spacing between the electrodes is adjustable from the outside, and the electrode driving mechanism has a mounting plate to which the remaining electrodes are mounted and a slide bearing, and guides the linear movement of the mounting plate. A ball screw for linearly driving the mounting plate in a vacuum-sealed state from the outside, and a drive unit for rotationally driving the shaft of the ball screw from the outside. On source.