JPH02152140A - Ion drawing-out electrode - Google Patents

Abstract

PURPOSE:To increase the amount of ion beams and to prevent the position slippage of holes and the like by laminating conductors on the whole surface of a conductive plate through an insulator, and forming holes or slits to draw out ion beams to the resultant laminate body. CONSTITUTION:A conductor plate is made as a screen electrode 1, a conductor made by laminating thin membranes or thick membranes is made as an acceleration electrode 2, and an insulator 10 of a thin membrane or a thick membrane is placed between the both electrodes, to form a unitary structure of a laminate body, on which holes 15 or slits are formed. As a result, the interval between the both electrodes 1 and 2 can be made very small and even, and the amount of ion beams can be increased. And since no position slippage of holes 15 owing to a bending of electrode and the like is avoided, and a large area of ion drawing-out electrode can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ion extraction electrode used in an ion source used for surface modification, thin film formation, etching, and other processes.

2. Description of the Related Art Conventional technology - E(,
An R (electron cyclotron resonance) type ion source is shown in FIG.

In Fig. 5, 3 is a spacer made of an insulator;
The electrodes were insulated and their spacing was kept uniform. It's a special thing.

4 is a microwave power for generating discharge, 5 is a discharge chamber that generates plasma 6 inside it, 7 is a DC power supply that applies a positive voltage to the discharge chamber 5 and the screen electrode 1, and 8 is a negative voltage to the accelerating electrode. 9 is the extracted ion beam.

Note that the ECR type ion source uses a solenoid or the like for applying a resonant magnetic field to the microwave power 4, but this is omitted in this figure. Also, the DC power supply 8 is omitted and the acceleration type f! 2 may be set to ground potential.

If a part of the cross section of the ion extraction electrode used in the above is enlarged, as shown in FIG.
It consists of In order to prevent ions from colliding with the accelerating electrode 2, these two electrodes must be aligned so that the positions of the respective holes 25 are exactly aligned. In order to extract an ion beam of 1, it is necessary to generate a uniform electric field over the entire surface, and for this purpose the electrode spacing d must be kept uniform.

It is known that the current density j of the ion beam extracted from two parallel electrodes follows the following Child's law.

j-(4ε0/9) (2e/m)1/2Vt3/2/
Ie2 Here, ε0 is the dielectric constant, e/m is the ratio of ion charge to mass, Vt is the potential difference between the two electrodes, and Iei is the difference between the electric charges.

FIG. 7 is an explanatory diagram of the principle of the ion extraction electrode, and shows an enlarged view of the vicinity of the hole of the screen electrode 1 and the acceleration electrode 2, and the state of the potential on the center line of the hole between the two electrodes.

In the figure, Vs and Va are voltages applied by the DC power supplies 7 and 8 in FIG. 5, respectively, and 9 is an ion beam.

In the case of an ion extraction electrode with holes 25 as shown in FIG.
Child's law above! e is de in Figure 7, and V
t corresponds to Vs+Va.

However, according to experience, the amount of ion beam does not change much even if Va is changed, and the current density j is determined almost only by VS.

As mentioned above, the ion source is used to process thick films, but in order to improve the processing speed, it is necessary to increase the amount of ion beam extracted.

for that, 1. Decrease the picture electrode spacing d.

2. Reduce the hole diameter φD.

3. Increase the voltage applied by the two DC power supplies 7 and 8.

The following methods are used.

However, due to mechanical strength such as bending of the electrode, and machining of holes using ball holders, etc., the thickness of the electrode is 0.5 to 1.5 mm.
Approximately mm, electrode spacing d is 0.5 ~ b hole diameter φD is φ2.0
~3. Something of the order of OI is used.

Problems to be Solved by the Invention However, in recent years, there has been a strong demand to further improve the processing speed of thin films, and the development of a technology that can further increase the amount of ion beams has become a future technical issue. In addition, when forming a film, the energy of the ion beam is several e
A low energy of about V to several tens of eν is appropriate, and it is said that if the energy exceeds a few hundred eV, as with conventional ion sources, the crystals of the thin film formed will be destroyed, making it impossible to obtain a high-quality thin film. ing.

On the other hand, the energy of the ion beam is proportional to Vs.

Therefore, if VS is lowered to obtain a low-energy ion beam, Vt will also drop and the ion beam amount will decrease. There is also the issue of realizing energy conversion.

Furthermore, in order to perform large-area processing, an ion source is required to have a large area, and accordingly, an ion extraction electrode must also have a large area.

However, when the electrode area is increased, there is a problem that it becomes difficult to keep the electrode spacing uniform over the entire surface of the electrode, but the holes aligned, due to the bending of the electrode.6 Means for Solving the Problem The present invention is characterized in that a conductor is laminated on almost the entire surface of a conductor plate via an insulator, and holes or slits are formed in the resulting laminate to prevent ions from being drawn out. Preferably, the insulator and conductor to be laminated are thin films or thick films, and more preferably, the insulator contains any one of oxide, carbide, and nitride of the conductor plate.

Function According to the present invention, a conductor plate is used as a screen electrode, a conductor laminated with a thick film rather than a thin film is used as an accelerating electrode, and a hole is formed as an integral structure of the laminate with a thin film or thick film insulator interposed between the two electrodes. Alternatively, since a slit is formed, the distance between the two electrodes can be made extremely small and uniform, so that the amount of ion beam can be increased. Further, since there is no problem that the position of the hole is shifted due to bending of the electrode, etc., it is possible to obtain an ion extraction electrode with a second area.

EXAMPLE An example of the ion extraction electrode according to the present invention will be described with reference to FIG.

In FIG. 1, 1 is a screen electrode made of a tungsten plate with a thickness of 0.1 mm, 2 is an acceleration electrode made of a tungsten thin film with a thickness of 1 μm, and 10 is a screen electrode with a thickness d of 1 μm.
The ion extraction hole 15 has a hole diameter φD of φ1 mm.

The method for producing this ion extraction electrode is as follows.

First, a base material of a tungsten plate with a thickness of 0.1 mm, which will become the screen electrode 1, is heated and oxidized in an oxygen stream to form an insulating film 1o with a uniform thickness of 1 μm.

Next, the insulating film on one side is removed by etching, a tungsten thin film is formed by sputtering on the insulating film 10 remaining on the other side to form the accelerating electrode 2, and then an ion extraction hole 15 is opened by etching.

As mentioned above, this ion extraction electrode is connected to the base material 1 of the conductor plate.
An insulating film 10 and a thin film of tungsten, which is a conductor, are laminated on the entire upper surface.

An example in which this ion extraction electrode is used as an ion source will be explained based on FIG. 2.

11 is the ion extraction electrode shown in FIG. 1, and the same components as in the conventional ion source shown in FIG. 5 are given the same numbers.

12 is an accelerating type f! voltage of the DC power supply 8. This is a conductive ring for applying voltage to 2.

Since the ion extraction electrode according to the present invention has a relatively small electrode spacing d and a small hole diameter φD, it is possible to shorten de in FIG. 7, and the current density j is larger than Child's law.
In other words, the amount of ion beam can be increased.

Furthermore, by using the ion extraction electrode of the present invention, it is possible to lower the potential difference Vt required to obtain the same amount of ion beam as in the past, so the voltage applied to the screen electrode 1 can be lowered and a low-energy ion beam can be obtained. be able to.

Furthermore, since the ion extraction electrode of the present invention has an integral structure with the insulator 10 that maintains the distance between the screen electrode 1, the acceleration electrode 2, and the picture electrode, the ion extraction electrode of the present invention has a structure in which the screen electrode 1, the acceleration electrode 2, and the insulator 10 that maintains the distance between the picture electrodes are integrated. It is also possible to create a large-area ion extraction electrode without the problem of misalignment of the spacing and hole positions.

Although tungsten was used as the electrode material in this embodiment, other materials may of course be used. Furthermore, depending on the electrode material, nitride or carbide may be better than oxide as in this embodiment. Furthermore, the insulating film may be formed by, for example, a CVD method other than the method of this embodiment.

Conventional ion extraction electrodes sometimes use means to change the hole diameters of the screen electrode and accelerating electrode in order to increase the amount of ion beam.

In the present invention, for example, the ion extraction hole 15 is made into a tapered shape, and the diameter of the acceleration type fi2 is made smaller than that of the screen electrode 1, as shown in FIG.
It can be made as large as .

Further, as the ion extraction electrode, three electrodes may be used, which are the two electrodes described above and an electrode at ground potential. In that case, an insulating film 13 and a grounding agent 14 may be further laminated on the accelerating electrode 2 as shown in FIG.

Effects of the Invention According to the present invention, by integrally laminating the conductive plate and the conductive picture electrode via an insulator, the picture electrode interval can be made as small as possible and the amount of ion beam can be increased. Since the potential difference required to obtain the amount of ion beam can be lowered, the voltage applied to the conductor plate (screen electrode 8i) can be lowered, and the energy of the ion beam can be lowered.

Further, since the electrode spacing is uniform over the entire surface of the electrode, and there is no problem of the position of the hole being shifted due to bending of the electrode, etc., a large area of ion extraction ti can be obtained.

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view of an embodiment of the ion extraction electrode of the present invention, FIG. 1(b) is a cross-sectional view of the same, and FIG. Figure 3 (a
), (b) and FIG. 4 are configuration diagrams of other embodiments of the ion extraction electrode of the present invention, FIG. ) is a perspective view of a conventional ion drawer, and (b) is a cross-sectional view.
FIG. 7 is an explanatory diagram of the principle of the ion extraction electrode. 1... Screen electrode, 2... Accelerating electrode, 10...
- Insulator, 15...Ion extraction hole. Name of agent: Patent attorney Shigetaka Awano (1 person)

Claims (3)

[Claims] (1) An ion extraction electrode characterized in that a conductor is laminated on almost the entire surface of a conductor plate with an insulator interposed therebetween, and holes or slits for extracting ions are formed in the resulting laminate. (2) The ion extraction electrode according to claim 1, wherein the insulator and conductor to be laminated are thin films or thick films. (3) The ion extraction electrode according to claim 1 or 2, wherein the insulator contains any one of oxide, carbide, and nitride of the conductor plate.