JPH09213227A - Ion source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the distribution of the current density of the ion beams on a base evenly without generating a part where almost no ion beam is radiated on the base, by forming outlet holes with plural sorts of diameters on an electrode, in an ion source device. SOLUTION: The hole diameter of the outlet holes 13 at the center of an electrode 7 is made smaller than the hole diameter of the outlet holes 14 at the peripheral edge. As a result, the ion beam amount drawn out from the center of the electrode 7 is reduced, and the distribution of the current density of the ion beams on a base can be corrected to be even at the center and at the peripheral edge. On the contrgry, when the currcet density of the ion beams at the peripheral edge is high, the diameter of the outlet holes at the peripheral edge is made smaller than the diameter of the outlet holes at the center. Consequently, the distribution of the current density of the ion beams on the base can be made even.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an ion source device having a porous electrode having a plurality of extraction holes for extracting an ion beam from plasma.

[0002]

2. Description of the Related Art A conventional ion source device will be described with reference to FIG. 2 showing a cut side view and FIG. 3 showing a partially enlarged front view.

In these figures, 1 is a housing, 2 is a plasma chamber formed by the housing 1, and 3 is a filament introduced into one side of the housing 1 through an insulating support 4.
It is heated to a high temperature by the filament power supply and emits thermoelectrons. Reference numeral 5 denotes an ionization gas inlet formed on one side of the housing 1, and a required type and amount of gas are introduced into the plasma chamber 2 through the inlet 5.

6 is a molybdenum, aluminum or copper, for example, a porous electrode system having a diameter of 300 mmφ,
The filament 3 of the housing 1 is composed of a porous electrode 7 for acceleration, a porous electrode 8 for deceleration, and a porous electrode 9 for grounding.
The electrodes 7, 8 and 9 are provided in the openings at positions facing each other, and the electrodes 7, 8 and 9 are supported via an insulator. 10 is each electrode 7, 8,
A plurality of extraction holes each having a hole diameter of, for example, 4 mmφ are formed in each of the electrodes 9. As shown in FIG. 3, the electrodes 7, 8 and 9 are evenly arranged at the positions of a grid of 5 mm intervals. 1
Reference numeral 1 denotes a plurality of magnets arranged on the outer surface of the housing 1, and adjacent magnets 11 have different polarities to form a cusp magnetic field.

The thermoelectrons from the filament 3 are accelerated with the casing 1 and collide with the ionizing gas from the inlet 5, plasma 12 is generated, and the plasma 12 is a cusp magnetic field generated by each magnet 11. As a result, the ions are confined in the central portion of the housing 1, and the ions in the plasma 12 are extracted as an ion beam from the extraction holes 10 of the electrodes 7, 8, 9 by the extraction action of the porous electrode system 6.

[0006]

By the way, in the above-mentioned conventional apparatus, when the distribution of the current density of the ion beam is controlled, the extraction holes 10 of the porous electrode 7 are arranged in a non-uniform manner. That is, the number of holes in the portion where the current density of the ion beam is high is reduced. However, when the plasma has a uniform density, this method can also be dealt with, but as shown in FIG. 4, when the plasma is non-uniform and the divergence angle of the ion beam is small, this The method is difficult to deal with.

That is, when the divergence angle of the ion beam is small, the overlap of the ion beams from the extraction holes 10 on the substrate is small, and in such a case, the central portion corresponding to the high current density portion of the ion beam. There is a problem that reducing the number of extraction holes 10 results in a portion where the ion beam is not irradiated at all.

Depending on the shape of the substrate and the like, it may be desired to obtain a desired current density distribution of the ion beam.

In consideration of the above points, the present invention produces a portion where the ion beam is not irradiated at all on the substrate even when the plasma density distribution is non-uniform and the divergence angle of the ion beam is small. It is an object of the present invention to provide an ion source device capable of correcting the distribution of the current density of the ion beam and obtaining a desired distribution.

[0010]

In order to solve the above-mentioned problems, the present invention is directed to a case in which an ionizing gas inlet is formed to generate plasma, and a plurality of extraction holes for extracting an ion beam from the plasma. In the ion source device including the porous electrode having the above-mentioned structure, the diameter of the extraction hole at the center of the electrode and the diameter of the extraction hole at the peripheral portion of the electrode are different.

Therefore, since the ion beam extracted from one extraction hole is determined by the plasma density, the electric field to the plasma, and the hole diameter of the electrode in contact with the plasma, for example, when the current density of the ion beam at the center is high, By making the diameter of the extraction hole of the part smaller than the diameter of the peripheral part, the amount of the ion beam extracted from the center of the electrode is reduced, and the distribution of the current density of the ion beam in the center of the substrate is reduced. Unlike the case where the number of extraction holes is reduced, even if the distribution of the plasma density is non-uniform and the divergence angle of the ion beam is small, there is no part where the ion beam is not irradiated on the substrate, The current density distribution of the ion beam on the substrate is uniformly corrected.

On the contrary, when the current density of the ion beam at the peripheral portion is high, the diameter of the extraction hole at the peripheral portion is made smaller than the diameter of the extraction hole at the central portion so that the ion beam on the substrate is The current density distribution is corrected uniformly.

Further, the present invention is not limited to the central portion and the peripheral portion, and the present invention is one in which the electrode is formed with extraction holes having a plurality of kinds of hole diameters.

Therefore, in this case, a desired current density distribution of the ion beam can be obtained depending on the shape of the substrate.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment will be described with reference to FIG. 1 showing a partial front view. In this case, the current density of the ion beam in the central portion is high, and in this figure, the points different from FIG. 3 are as follows. Reference numeral 13 denotes a center extraction hole having a hole diameter of, for example, 2 mmφ formed in the central portion of the accelerating porous electrode 7, 14 denotes a peripheral extraction hole having a hole diameter of, for example, 4 mmφ formed at a peripheral portion of the electrode 7, and 15 denotes a center extraction hole. 13 and the peripheral draw-out hole 14 are intermediate draw-out holes having a hole diameter of, for example, 3 mmφ.
The holes 4, 15 are evenly arranged at the positions of the grid of the electrode 7 at intervals of 5 mm, and the diameters of the extraction holes 13, 14, 15 are reduced from the peripheral edge of the electrode 7 toward the center. , Corresponding to the plasma density shown in FIG. That is, the hole area × plasma density≈constant.

Next, examples will be described. The acceleration energy of the ion beam is 40 KV and the porous electrode system 6
As a result of measuring the current density of the ion beam at a position of 300 mm from, it was found that the current density distribution of the ion beam was within ± 15% within 300 mmφ. That is, the current density distribution of the ion beam on the substrate was almost uniform.

As a result of measuring the current density of the ion beam using the apparatus of FIG. 2 under the same conditions as in the above-mentioned embodiment, the shape was close to the non-uniform plasma density distribution shown in FIG. That is, the distribution of the current density of the ion beam in the central portion of the substrate is high and the peripheral portion is low.

As described above, the extraction hole 1 at the center of the electrode 7
3 is smaller than the diameter of the extraction hole 14 in the peripheral portion, the amount of the ion beam extracted from the central portion of the electrode 7 is reduced, and the current density distribution of the ion beam on the substrate is distributed in the central portion and the peripheral portion. Can be corrected uniformly.

Contrary to the above, when the current density of the ion beam at the peripheral portion is high, the diameter of the extraction hole at the peripheral portion is made smaller than the diameter of the extraction hole at the central portion. By making this smaller, the distribution of the current density of the ion beam on the substrate can be made uniform.

Further, depending on the shape of the substrate and the like, the hole diameter of the extraction hole of each part of the electrode can be appropriately changed to obtain a desired current density distribution of the ion beam on the substrate. The present invention can be applied to any porous electrode regardless of the discharge method such as direct current discharge and high frequency discharge, the number of electrodes, and the material.

Further, in the above-described embodiment, the diameter of the extraction hole of the electrode 7 is continuously reduced from the peripheral portion of the electrode 7 toward the central portion, but the peripheral portion is large, the intermediate portion is middle, and the central portion is small. It may be reduced stepwise.

Further, in the above-mentioned embodiment, the porous electrode is used, but a slit-type electrode may be used, and by making the width of the slit in the central portion smaller than the width of the slit in the peripheral portion, the same as in the above-mentioned embodiment is obtained. Produce an effect.

[0023]

Since the present invention is constructed as described above, it has the following effects. In the ion source device of the present invention, when the current density of the ion beam in the central portion is high, the diameter of the extraction hole 13 in the central portion of the porous electrode 7 is made smaller than the diameter of the peripheral portion so that the central portion of the electrode 7 is Unlike the case where the number of extracted ion beams is reduced, the distribution of the current density of the ion beam at the center of the substrate is reduced, and the number of extraction holes is reduced, the plasma density distribution is non-uniform and the ion beam Even if the divergence angle of is small,
It is possible to uniformly correct the current density distribution of the ion beam on the substrate without generating a portion on the substrate where the ion beam is not irradiated at all.

On the contrary, when the current density of the ion beam at the peripheral portion is high, the diameter of the extraction hole at the peripheral portion is made smaller than the diameter of the extraction hole at the central portion, so that the ion beam on the substrate is The current density distribution can be corrected uniformly.

Further, not only the central part and the peripheral part, but also the extraction holes having plural kinds of hole diameters are formed in the electrode, so that the desired current density distribution of the ion beam can be obtained depending on the shape of the substrate and the like. .

[Brief description of drawings]

FIG. 1 is a partial front view of an embodiment of the present invention.

FIG. 2 is a cut side view of a conventional example.

3 is an enlarged front view of a part of FIG. 2. FIG.

FIG. 4 is a diagram showing a distribution of plasma density.

[Explanation of symbols]

 1 Case 5 Inlet 7 Porous Electrode 8 Porous Electrode 9 Porous Electrode 12 Plasma 13 Extraction Hole

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[Procedure amendment]

[Submission date] September 17, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

In order to solve the above problems SUMMARY OF THE INVENTION The present invention includes a housing for generating a flop plasma, and a porous-type electrodes forming a plurality of extraction holes to draw than the ion beam plasma In the ion source device, the diameter of the extraction hole at the center of the electrode is different from the diameter of the extraction hole at the peripheral edge.

Claims (2)

[Claims] 1. An ion source apparatus comprising: a housing in which an ionizing gas inlet is formed to generate plasma; and a porous electrode in which a plurality of extraction holes for extracting an ion beam from the plasma are formed. An ion source device in which extraction holes having a plurality of kinds of hole diameters are formed in the electrode. 2. An ion source device comprising: a casing in which an ionization gas inlet is formed to generate plasma; and a porous electrode having a plurality of extraction holes for extracting an ion beam from the plasma, An ion source device in which the diameter of the extraction hole at the center of the electrode and the diameter of the extraction hole at the peripheral portion are different.