WO2015080239A1

WO2015080239A1 - Lead-out electrode and ion source

Info

Publication number: WO2015080239A1
Application number: PCT/JP2014/081506
Authority: WO
Inventors: 俊次黒岡
Original assignee: 富士フイルム株式会社
Priority date: 2013-11-29
Filing date: 2014-11-28
Publication date: 2015-06-04
Also published as: JPWO2015080239A1; TW201521068A

Abstract

The present invention provides a lead-out electrode by which it is possible to attain an ion beam having a high degree of straightness. This lead-out electrode (1) is provided with: an insulating layer (2) made of an anodic oxide film; an acceleration electrode (3) disposed on one surface of the insulating layer (2); and a plurality of through-holes (4) passing through the acceleration electrode (3) and the insulating layer (2) in the thickness direction, the aspect ratio (average length (5)/average opening diameter (6)) of the penetrating hole (4) being 16 to 1000 inclusive.

Description

Extraction electrode and ion source

The present invention relates to an extraction electrode and an ion source, and more particularly to an extraction electrode and an ion source for generating an ion beam.

In recent years, ion sources have been used in various fields such as vacuum film forming devices, focused ion beam devices (FIB (Focused Ion Beam) devices), ion milling devices, and ion engines used in the space industry. In general, an ion source includes an ion generation chamber that generates ions and an extraction electrode that is set to a low potential with respect to the ion generation chamber. Among the ions generated in the ion generation chamber, positive ions having a positive charge are extracted while accelerating from the ion generation chamber toward the extraction electrode in accordance with the electric field formed between the ion generation chamber and the extraction electrode. As a result, an ion beam is generated, and the generated ion beam passes through a plurality of through holes formed in the extraction electrode and is emitted to the outside.

Here, the extraction electrode plays an important role in the generation of an ion beam, and various extraction electrodes for generating a desired ion beam have been proposed. For example, Patent Document 1 states that “an ion extraction electrode that extracts ions from an ion source in which plasma is generated, and the ion extraction electrode includes a plurality of ion extraction holes (through holes) that penetrate the ion extraction electrode. An ion extraction electrode characterized by comprising a plate-like body having a curved surface region that protrudes outward from the discharge chamber "is disclosed (claim 5).

Japanese Patent Laid-Open No. 2001-210245

However, since a plurality of through holes are formed in the extraction electrode of Patent Document 1 using a drill or the like, the aspect ratio (average length / average opening diameter) of the through holes cannot be increased. For this reason, an ion beam with low linearity also passes through the through hole, and it is difficult to obtain an ion beam with high linearity.

Therefore, an object of the present invention is to provide an extraction electrode and an ion source capable of obtaining an ion beam having high straightness.

As a result of intensive studies to achieve the above-mentioned problems, the present inventor has found that a plurality of through holes of the extraction electrode have an aspect ratio in a predetermined range, whereby an ion beam having high straightness can be obtained. Completed the invention.
That is, the present invention provides an extraction electrode and an ion source having the following configuration.

(1) An extraction electrode for extracting ions to form an ion beam,
An insulating layer made of an anodized film of a valve metal;
An accelerating electrode disposed on one surface of the insulating layer;
An acceleration electrode and a plurality of through holes penetrating the insulating layer in the thickness direction,
An extraction electrode having an aspect ratio, which is a ratio of an average length of through holes and an average opening diameter, of 16 or more and 1000 or less.

(2) The extraction electrode according to (1), wherein the aspect ratio is 22 or more and 500 or less.

(3) The extraction electrode according to (1) or (2), wherein the ratio of the aperture ratio to the aspect ratio of the through hole is 1.0 or more and 3.5 or less.

(4) The extraction electrode according to any one of (1) to (3), wherein the average thickness of the insulating layer is 2 μm or more and 300 μm or less.

(5) The extraction electrode according to any one of (1) to (4), wherein an aperture ratio due to the through hole is 3% or more and 90% or less.

(6) The extraction electrode according to any one of (1) to (5), wherein an average opening diameter of the through holes is 30 nm or more and 50 μm or less.

(7) It further has a ground electrode disposed on the other surface opposite to the one surface of the insulating layer,
The lead electrode according to any one of (1) to (6), wherein the plurality of through holes penetrate the acceleration electrode, the insulating layer, and the ground electrode in the thickness direction.

(8) an ion generation chamber for generating ions;
The extraction electrode according to any one of (1) to (7), which is disposed to face the ion generation chamber;
An ion source having a power source for applying a potential to the extraction electrode.

According to the present invention, it is possible to provide an extraction electrode and an ion source capable of obtaining an ion beam with high straightness.

FIGS. 1A and 1B are simplified views showing an example of a preferred embodiment of an extraction electrode according to the present invention, FIG. 1A is a front view, and FIG. 1B is a cross-sectional view taken along section line Ib-Ib in FIG. It is. It is sectional drawing which shows the modification of the extraction electrode of this invention. It is sectional drawing which shows an example of the ion source of this invention. It is sectional drawing which shows the modification of the ion source of this invention.

[Extraction electrode]
The extraction electrode of the present invention is an extraction electrode for extracting ions to form an ion beam, an insulating layer made of an anodized film of a valve metal, an acceleration electrode disposed on one surface of the insulating layer, An acceleration electrode and a plurality of through holes penetrating the insulating layer in the thickness direction are provided, and the aspect ratio (average length / average opening diameter) of the through holes is 16 or more and 1000 or less.
Next, the extraction electrode of the present invention will be described with reference to FIG.

FIG. 1 is a simplified diagram showing an example of a preferred embodiment of the extraction electrode of the present invention. FIG. 1 (A) is a front view, and FIG. 1 (B) is a section line Ib-Ib in FIG. 1 (A). It is sectional drawing seen from.
The lead electrode 1 of the present invention includes an insulating layer 2 having a flat plate shape and an acceleration electrode 3 disposed on one surface 2a of the insulating layer 2, and penetrates the insulating layer 2 and the acceleration electrode 3 in the thickness direction. A plurality of through holes 4 extending in a straight line are formed in Z. That is, the plurality of through holes 4 are formed such that the plurality of through holes 4 a formed in the insulating layer 2 and the plurality of through holes 4 b formed in the acceleration electrode 3 communicate with each other.

Here, when the acceleration electrode 3 is disposed in an ion source described later, a different potential is applied to the ion generation chamber. Thereby, an electric field is formed between the ion generation chamber and the acceleration electrode 3, and ions generated in the ion generation chamber are extracted while being accelerated according to the electric field, thereby forming an ion beam. The ion beam formed by the accelerating electrode 3 enters the plurality of through holes 4, and the ion beam having low rectilinearity is regulated by the inner peripheral surfaces of the plurality of through holes 4 and passes through the plurality of through holes 4. In other words, only the ion beam having a high linearity is emitted through the plurality of through holes 4 to the outside.
In the present invention, the plurality of through holes 4 are formed so that the aspect ratio indicating the ratio of the average length 5 to the average opening diameter 6 is 16 or more and 1000 or less. By setting the aspect ratio of the plurality of through holes 4 to 16 or more, an ion beam having high straightness can be obtained, and by setting the aspect ratio of the plurality of through holes 4 to 1000 or less, the ion beam can be transmitted. It can be ensured that the amount of ion beam passing through each through-hole 4 is greatly reduced. The plurality of through holes 4 preferably have an aspect ratio of 22 or more and 500 or less for the purpose of further improving the straightness of the ion beam. Furthermore, it is preferable that the plurality of through holes 4 have an aspect ratio of 24 or more and 50 or less for the purpose of improving both straightness and passage of the ion beam.

Further, as shown in FIG. 2, the lead electrode 1 of the present invention preferably further includes a ground electrode 7 disposed on the other surface 2b opposite to the one surface 2a of the insulating layer 2. As a result, the ion beam emitted to the outside through the plurality of through holes 4 is suppressed from being pulled back by the potential of the accelerating electrode 3, and the amount of the ion beams emitted from the plurality of through holes 4 is reduced. Can be suppressed.

The aperture ratio of the extraction electrode 1 of the present invention is preferably 3% or more and 90% or less, and more preferably 30% or more and 90% or less. By setting the aperture ratio to 3% or more, it is possible to suppress the total amount of ion beams passing through the plurality of through holes 4 from being greatly reduced, and to keep the ion beam current amount high. Further, by setting the aperture ratio to 90% or less, sufficient strength can be imparted to the extraction electrode 1, and deterioration due to multiple use of the extraction electrode 1 can be suppressed.

In addition, the extraction electrode 1 has a ratio of the aperture ratio with respect to the aspect ratio of the plurality of through holes 4 of 0.1 or more and 3 for the purpose of improving the passability while maintaining high straightness of the ion beam transmitted through the plurality of through holes. .5 or less is preferable. The ratio of the aperture ratio to the aspect ratio of the plurality of through-holes 4 is 1.0 or more because the ion beam current amount is kept high by further improving the passability while keeping the straightness of the ion beam high. More preferably, it is 5 or less. Further, the ratio of the aperture ratio to the aspect ratio of the plurality of through holes 4 is more preferably 2.0 or more and 3.5 or less for the purpose of further improving the passability while keeping the straightness of the ion beam high.

In addition, the values of the average opening diameter and the average length of the plurality of through-holes described above are obtained by analyzing the SEM images of the extraction electrodes acquired at a magnification of 100,000 times, respectively. Specifically, the diameters and lengths of all the through holes existing in the field of view of the SEM image of the extraction electrode are calculated, and the average values are obtained for the diameters and lengths of all the through holes. When the number of through holes existing in one field of view is less than 50, the plurality of fields of view are photographed, and the average value is obtained by calculating the diameter and length of at least 50 through holes. did.
The aperture ratio of the extraction electrode described above was obtained by calculating the area of the through hole and the area of the visual field existing in the visual field for the SEM image of the extraction electrode.

[Insulation layer]
The insulating layer is a structure made of an anodized film of a valve metal and improves the straightness of the ion beam.
In the present invention, the insulating layer preferably has an average thickness of 2 μm to 300 μm. By setting the average thickness of the insulating layer to 2 μm or more, it is possible to reliably remove the ion beam having low linearity when the ion beam passes through a plurality of through holes (portion represented by reference numeral 4a in FIG. 1). In addition, by setting the average thickness of the insulating layer to 300 μm or less, it is possible to improve the passability of an ion beam passing through a plurality of through holes (portion represented by reference numeral 4a in FIG. 1). In addition, as shown in FIG. 2, when the acceleration electrode is disposed on one surface of the insulating layer and the ground electrode is disposed on the other surface, the average thickness of the insulating layer is within the above range. It is possible to ensure sufficient insulation.

The insulating layer can be manufactured by anodizing the valve metal substrate and penetrating pores generated by the anodic oxidation. As the valve metal, for example, aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth and antimony are used, and aluminum is preferably used.
Compared to the case where a plurality of through-holes are formed using a conventional drill or the like by forming a plurality of through-holes to be described later on the extraction electrode using the pores generated by anodization, the aspect ratio Can be easily formed. Further, by forming a plurality of through holes, which will be described later, in the extraction electrode using pores generated by anodization, the plurality of through holes can be easily formed at a small pitch.
As the anodizing treatment, a conventionally known method can be used, but from the viewpoint of increasing the regularity of the plurality of through holes, it is preferable to use a self-ordering method or a constant voltage treatment. Here, as for the self-ordering method and the constant voltage process of the anodizing process, the same processes as those described in paragraphs [0056] to [0108] and [FIG. 3] of Japanese Patent Application Laid-Open No. 2008-270158 are performed. Can be applied.
Examples of the penetration process include the same methods as those described in paragraphs [0110] to [0121] of Japanese Patent Application Laid-Open No. 2008-270158 and [FIG. 3] and [FIG. 4].

[Acceleration electrode]
The acceleration electrode is an electrode that draws positive ions having positive charges from an ion generation chamber of an ion source, which will be described later, to form an ion beam.
The accelerating electrode is not particularly limited as long as it is made of a conductive material. For example, refractory metal materials such as tantalum, tungsten, molybdenum, and nickel are preferably exemplified.
The acceleration electrode can be formed on one surface of the anodic oxide film, which is the insulating layer, using, for example, sputtering.

[Ground electrode]
The ground electrode suppresses the ion beam emitted from the plurality of through holes from being pulled back to the extraction electrode side. The ground electrode is not particularly limited as long as it is made of a conductive material. For example, the ground electrode can be made of the same material as the acceleration electrode described above.
The ground electrode can be formed on the other surface of the anodic oxide film, which is the insulating layer, using, for example, sputtering.

[Multiple through holes]
The plurality of through holes preferably have an average opening diameter (portion represented by reference numeral 6 in FIG. 1) of 30 nm or more and 50 μm or less. When the average aperture diameter is 30 nm or more, the passability of the ion beam passing through the plurality of through holes can be improved, and when the average aperture diameter is 50 μm or less, the ion beam with low straightness is surely removed. Can do.
The plurality of through holes preferably have an average pitch (portion represented by reference numeral 8 in FIG. 1) of 40 nm or more and 500 nm or less. When the average pitch is 40 nm or more, sufficient strength can be imparted to the extraction electrode, and when the average pitch is 500 nm or less, the amount of the ion beam that collides with the surface of the extraction electrode can be suppressed and more The ion beam can enter the plurality of through holes.

The density of the plurality of through holes is preferably ² million pieces / mm ² or more, more preferably 10 million pieces / mm ² or more, in order to keep the ion beam current amount high, more preferably 50 million pieces. / Mm ² or more is more preferable, and 100 million / mm ² or more is particularly preferable.

[Ion source]
The ion source of the present invention will be described in detail below.
The ion source of the present invention is an ion source having an ion generation chamber for generating ions, the above-described extraction electrode disposed to face the ion generation chamber, and a power source for applying a potential to the extraction electrode.

FIG. 3 is a schematic cross-sectional view showing an example of a preferred embodiment of the ion source 21 of the present invention.
The ion source 21 of the present invention includes an ion generation chamber 22, an extraction electrode 1 disposed opposite the ion generation chamber 22, and a power supply that applies a potential so that the extraction electrode 1 has a lower potential than the ion generation chamber 22. 23.
The ion generation chamber 22 includes a plasma generation chamber 24 that generates plasma P, a gas supply unit 25 that supplies a source gas into the plasma generation chamber 24, and a confinement unit that confine the generated plasma P in the plasma generation chamber 24. 26 and an extraction port 27 formed on a side surface of the plasma generation chamber 24 facing the extraction electrode 1.
As described above, the extraction electrode 1 has the acceleration electrode 3 disposed on one surface 2a of the insulating layer 2 and the installation electrode 7 disposed on the other surface 2b of the insulating layer 2. It is installed so as to face the ion generation chamber 22. As shown in FIG. 1, the extraction electrode 1 may be one in which the acceleration electrode 3 is disposed only on one surface 2a of the insulating layer 2 and the ground electrode 7 is not disposed on the other surface 2b. Thus, the accelerating electrode 3 can be installed so as to face the ion generation chamber 22.

The power source 23 connects the plasma generation chamber 24 and the acceleration electrode 3 and applies a voltage to the plasma generation chamber 24 so that the potential of the acceleration electrode 3 is lowered. As a result, positive ions I in the plasma P confined in the plasma generation chamber 24 are extracted from the plasma generation chamber 24 toward the extraction electrode 1 through the extraction port 27 to form an ion beam.
When the ion beam reaches the extraction electrode 1, it passes through the plurality of through holes 4 and is emitted to the outside. At this time, since the plurality of through-holes 4 are formed with a high aspect ratio of 16 or more and 1000 or less, an ion beam with high straightness can be emitted to the outside. In addition, the ground electrode 7 can suppress pulling back of the ion beams emitted from the plurality of through holes 4, thereby suppressing a decrease in the amount of the ion beams emitted to the outside.

In this way, a highly linear ion beam is emitted from the plurality of through-holes 4 to the outside, for example, a substrate is disposed on the downstream side of the extraction electrode 1 with respect to the traveling direction of the ion beam, and high accuracy is achieved. A film can be formed.

Note that the ion source 21 of the present invention preferably has a neutralizer for neutralizing the charge of the ion beam on the downstream side of the extraction electrode 1 with respect to the traveling direction of the ion beam. Examples of the neutralizer include a heating filament that neutralizes the charge of the ion beam with thermionic electrons by heating. Thereby, the electric charge of an ion beam is neutralized and it can suppress that the ion beam discharge | released from the several through-hole 4 is influenced by a mutual electric charge and spread | diffused.

Further, as shown in FIG. 4, the ion source 21 of the present invention is arranged on the opposite side of the ion generation chamber 22 with the extraction electrode 1 interposed therebetween, that is, the ion measurement arranged opposite to the ground electrode 7 of the extraction electrode 1. A portion 28 can be provided.
The ion measuring unit 28 is installed when performing ion source maintenance or the like, and can measure the amount of ion beam current. Specifically, the ion measurement unit 28 includes a measurement substrate 29 arranged to face the extraction electrode 1, a plurality of measurement probes 30 arranged side by side on the surface of the measurement substrate 29, and a plurality of measurement probes 30. Each has an ammeter 31 connected thereto.
The ion beam emitted from the extraction electrode 1 is received by the plurality of measurement probes 30 of the ion measurement unit 28, and the current amount from the measurement probe is detected by the ammeter 31 to measure the current amount of the ion beam. be able to.

[Ion generation chamber]
<Plasma generation chamber>
The plasma generation chamber is for generating plasma by ionizing a source gas supplied from a gas supply unit described later. For example, the plasma generation chamber can generate plasma by ionizing the source gas by a method such as high-frequency discharge, microwave discharge, or laser irradiation.
Note that the plasma generation chamber is preferably made of a heat-resistant conductive material.

<Gas supply unit>
The gas supply unit supplies a raw material gas for generating plasma in the above-described plasma generation chamber. For example, the supply amount of the raw material gas is adjusted by a valve (a portion represented by reference numeral 30 in FIG. 3). By adjusting in step 1, the source gas can be supplied to the plasma generation chamber at a predetermined pressure.
Examples of the source gas include helium, hydrogen, argon, xenon and the like, and these may be used alone or in combination of two or more. The source gas can also contain gallium (Ga) ions, iron (Fe) ions, lithium (Li) ions, and the like.

<Containment part>
The confinement unit confines plasma in the plasma generation chamber by generating a magnetic field, an electric field, and the like in the plasma generation chamber. For example, by disposing a magnet so as to surround the plasma generation chamber and generating a so-called mirror magnetic field in the plasma generation chamber, diffusion of plasma can be suppressed and confined.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

Example 1
(A) Mirror finish (electropolishing)
A high-purity aluminum substrate (manufactured by Sumitomo Light Metal Co., Ltd., purity 99.99% by mass, thickness 0.4 mm) was cut so that it could be anodized in an area of 10 cm square, using an electrolytic polishing liquid having the following composition, a voltage of 25 V, Electropolishing was performed under conditions of a liquid temperature of 65 ° C. and a liquid flow rate of 3.0 m / min.
The cathode was a carbon electrode, and GP0110-30R (manufactured by Takasago Seisakusho Co., Ltd.) was used as the power source. The flow rate of the electrolyte was measured using a vortex type flow monitor FLM22-10PCW (manufactured by ASONE CORPORATION).

(Electrolytic polishing liquid composition)
・ 85% by mass phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 660 mL
・ Pure water 160mL
・ Sulfuric acid 150mL
・ Ethylene glycol 30mL

(B) Anodizing treatment step Next, the mirror-finished aluminum substrate was subjected to anodizing treatment for 1 hour in a 5.0 mol / L malonic acid electrolyte at a voltage of 115 V and a liquid temperature of 0 ° C. After the application, the film was immersed in an aqueous phosphoric acid solution having a concentration of 50 g / L and subjected to an oxide film dissolution treatment for 10 minutes under the condition of a liquid temperature of 30 ° C. This anodizing treatment and oxide film dissolution treatment were repeated four times.
In the anodizing treatment, the cathode was a stainless electrode, and a DC stabilized power source manufactured by Takasago Seisakusho Co., Ltd. was used as the power source. Further, NeoCool BD36 (manufactured by Yamato Kagaku Co., Ltd.) was used as the cooling device, and Pear Stirrer PS-100 (manufactured by EYELA Tokyo Rika Kikai Co., Ltd.) was used as the stirring and heating device.

Subsequently, an anodizing treatment and an oxide film dissolution treatment were performed on a 6-hour anodizing treatment with a 0.5 mol / L malonic acid electrolyte at a voltage of 115 V and a liquid temperature of 0 ° C. Then, it was immersed in a 50 g / L concentration phosphoric acid aqueous solution for 10 minutes to obtain an anodic oxide film having a thickness of 14 μm. In the obtained anodic oxide film, a plurality of pores having an average center-to-center distance of 300 nm were formed. To measure the center-to-center distance of multiple pores, use a scanning electron microscope S-4800 (manufactured by Hitachi High-Technologies Corporation) to shoot 5 images at 50k magnification at any location, and select any from each image. The distance between the centers of the selected pores was measured at 10 points, and the average value was taken as the distance between the centers of the pores.

(C) Penetration treatment step Next, aluminum was immersed by using a treatment liquid in which 0.1 mol / L copper chloride was mixed in a 20% by mass hydrochloric acid aqueous solution at a liquid temperature of 15 ° C until the aluminum was visually removed. The substrate is dissolved and further immersed in 5% by mass phosphoric acid at 30 ° C. for 30 to 180 minutes to remove the bottom of the anodized film, and a structure (insulating layer) comprising an anodized film having a plurality of through holes ) Was produced.

(D) Heat treatment Next, the structure obtained above was subjected to a heat treatment at a temperature of 400 ° C for 1 hour.

(E) Surface smoothing treatment Next, the surface of the structure was polished by 5 μm or more, and the opposite surface was polished by 5 μm or more.
Specifically, after lapping polishing with a sheet of silicon carbide (# 1200), polishing is performed with diamond slurry having a particle diameter of 2 μm, and further polishing is performed with diamond slurry having a particle diameter of 0.25 μm. To obtain a mirror state.

(F) Electrode formation treatment Next, input power while introducing argon gas at 0.5 Pa on both surfaces of the anodized film after the surface smoothing treatment using a sputtering apparatus (HSR-351L, manufactured by Shimadzu Corporation) Molybdenum (purity 99.95%) was vapor-deposited at 100 W for 600 seconds to form an extraction electrode by arranging an acceleration electrode and a ground electrode on one surface and the other surface of the insulating layer, respectively.

(Example 2)
When the anodizing treatment and the oxide film dissolving treatment are repeated in the (B) anodizing treatment step of Example 1, the treatment time of the anodizing treatment is set to 6 hours, and (E) the surface of the structure is 4 μm or more in the surface smoothing treatment A lead electrode was produced in the same manner as in Example 1 except that the opposite surface was polished by 4 μm or more.

Example 3
When repeating the anodizing treatment and the oxide film dissolution treatment in the anodizing treatment step (B) of Example 1, except that the malonic acid concentration in the anodizing treatment was 0.5 mol / L and the treatment time was 16 hours. A lead electrode was produced in the same manner as in Example 1.

Example 4
When the anodizing treatment and the oxide film dissolution treatment are repeated in the anodizing treatment step (B) of Example 2, the extraction electrode is formed in the same manner as in Example 2 except that the treatment time of the anodizing treatment is 56 hours. Was made.

(Example 5)
When the anodizing treatment and the oxide film dissolution treatment are repeated in the anodizing treatment step (B) of Example 1, the anodizing treatment uses an electrolyte of phosphoric acid having a concentration of 0.3 mol / L instead of malonic acid. A lead electrode was produced in the same manner as in Example 1 except that the treatment was performed for 1 hour under the conditions of 28 V and a liquid temperature of 0 ° C.

(Example 6)
The same method as in Example 5 except that, when the anodizing treatment and the oxide film dissolution treatment were repeated in the (B) anodizing treatment step of Example 5, the conditions of the anodizing treatment were set at a voltage of 45 V and a liquid temperature of 2 ° C. Thus, an extraction electrode was produced.

(Example 7)
The same method as in Example 5 except that, when the anodizing treatment and the oxide film dissolution treatment were repeated in the (B) anodizing treatment step of Example 5, the conditions of the anodizing treatment were set at a voltage of 91 V and the liquid temperature was 10 ° C. Thus, an extraction electrode was produced.

(Example 8)
When the anodizing treatment and the oxide film dissolving treatment were repeated in the (B) anodizing treatment step of Example 1, the oxide film dissolving treatment was carried out at a liquid temperature of 40 ° C. for 20 minutes in the same manner as in Example 1. A lead electrode was prepared.

Example 9
When the anodizing treatment and the oxide film dissolution treatment were repeated in the (B) anodizing treatment step of Example 1, the oxide film dissolution treatment was performed at a liquid temperature of 40 ° C. for 25 minutes in the same manner as in Example 1. A lead electrode was prepared.

(Comparative Example 1)
When the anodizing treatment and the oxide film dissolution treatment were repeated in the (B) anodizing treatment step of Example 1, the treatment time of the anodization treatment was set to 220 hours, and the oxide film dissolution treatment was performed at a liquid temperature of 40 ° C. for 25 minutes. Except for the above, an extraction electrode was produced in the same manner as in Example 1.

(Comparative Example 2)
When the anodizing treatment and the oxide film dissolution treatment are repeated in the anodizing treatment step (B) of Comparative Example 1, the treatment time for the anodizing treatment is 1 hour and the oxide film dissolving treatment is performed at a liquid temperature of 30 ° C. for 10 minutes. E) A lead electrode was produced in the same manner as in Comparative Example 1 except that the surface of the structure was polished by 5.75 μm or more and the opposite surface was polished by 5.75 μm or more in the surface smoothing treatment.

(Comparative Example 3)
By repeating the anodizing treatment and the oxide film dissolution treatment in the (B) anodizing treatment step of Comparative Example 1 in the same manner as in Comparative Example 1 except that the oxide film dissolution treatment was performed at a liquid temperature of 30 ° C. for 10 minutes. A lead electrode was prepared.

(Comparative Example 4)
A 1 mm thick molybdenum plate was cut into an area of 10 cm square, and drilled with water cooling using a 2 mmφ drill.

With respect to Examples 1 to 9 and Comparative Examples 1 to 4, the opening diameter of the through hole, the length of the through hole, and the opening ratio were measured.
As for the opening diameter and length of the through hole, an SEM image was analyzed to obtain an average value of the opening diameter and length. The results are shown in Table 1 below.
The aperture ratio was calculated by image analysis of the SEM image observed above. The results are shown in Table 1 below.

The aspect ratio of the through hole was calculated by determining the ratio of the length to the opening diameter. The results are shown in Table 1 below.
The aperture ratio / aspect ratio was calculated by obtaining the ratio of the aperture ratio to the aspect ratio calculated above. The results are shown in Table 1 below.

(Evaluation methods)
After the extraction electrode is installed in the Kaufman type ion source and the plasma generation chamber is evacuated to 0.6 mPa, 100 W is applied to the filament disposed in the plasma generation chamber while supplying argon gas from the gas supply unit at 30 mPa. Electric power was applied to generate plasma. Subsequently, an ion beam was formed by extracting positive ions from the plasma generation chamber by applying an acceleration potential of 1.2 kV to the acceleration electrode of the extraction electrode.

The straightness of the ion beam is detected by measuring probes with a diameter of 2 mm at a position of 100 mm from the extraction electrode in directions of 3 degrees, 5 degrees, and 10 degrees, respectively, with respect to the central axis of the through hole. The current value of the ion beam was measured using a microammeter (34410A, manufactured by Agilent Technologies). When the current value at this time can be obtained only with the measurement probe arranged in the direction of 3 degrees (the ion beam spread is less than 5 degrees), it is obtained with the measurement probe arranged in the directions of A, 3 degrees and 5 degrees. (If the ion beam spread is 5 degrees or more and less than 10 degrees), and B is obtained with a measurement probe arranged in directions of 3 degrees, 5 degrees, and 10 degrees (ion beam spread is 10 degrees or more). The straightness of the ion beam was evaluated. The results are shown in Table 1 below.

The amount of current of the ion beam is detected with a 2 mmφ measuring probe arranged 100 mm away from the extraction electrode directly under the through hole, and the current value at this time is measured by a microammeter (34410A, manufactured by Agilent Technologies). And measured. When the current amount at this time is greater than or equal to the current amount of Example 1, A, less than the current amount of Example 1 and 50% or more of the current amount of Example 1, B, the current amount of Example 1 The current amount of the ion beam was evaluated as C when less than 50% and 1% or more, and as D when less than 1% of the current amount of Example 1. The results are shown in Table 1 below.
In Comparative Example 1 and Comparative Example 3, the amount of current was less than 1% (Evaluation D), and thus the straightness and stability could not be evaluated.

The current stability of the ion beam is determined by detecting the ion beam with a 2 mmφ measuring probe placed 100 mm away from the extraction electrode directly under the through-hole, and the current value at this time is a microammeter (34410A, manufactured by Agilent Technologies). It measured using. The current stability of the ion beam was evaluated as A when the current value at this time was continuously obtained for 1 minute or longer, and B when it was not continuously obtained for 1 minute or longer. The results are shown in Table 1 below.

In Table 1 below, “-” indicates that the measurement value was not obtained and the evaluation could not be performed.

From the results shown in Table 1, Examples 1 to 9 in which the aspect ratio of the plurality of through holes is 16 or more and 1000 or less are compared with Comparative Examples 2 and 4 in which the aspect ratio of the plurality of through holes is less than 16. It was found that the straightness of the ion beam is improved. Further, in Comparative Examples 1 and 3 in which the aspect ratios of the plurality of through holes exceeded 1000, it was found that the amount of ion beam current was not detected, and most of the ion beams could not pass through the plurality of through holes. From this, it was found that by setting the aspect ratio of the plurality of through holes to 16 or more and 1000 or less, an ion beam having high straightness can be obtained with certainty.

Further, in Examples 1 to 9 in which the aspect ratio of the plurality of through holes is 16 or more and 1000 or less, the current stability of the ion beam is the same as that of Comparative Example 4 having the same aspect ratio as that of the conventional extraction electrode. It was found that an ion beam with high current stability in addition to straight travel is obtained.

Further, in Examples 2 to 9 in which the aspect ratio of the plurality of through holes is 22 or more and 500 or less, the straightness of the ion beam is further improved as compared with Example 1 in which the aspect ratio of the plurality of through holes is less than 22. I found out that
In Examples 2 and 7 to 9, in which the ratio of the aperture ratio to the aspect ratio of the plurality of through holes (opening ratio / aspect ratio) is 1.0 or more and 3.5 or less, the aperture ratio / aspect ratio is 1.0. It was found that both the straightness of the ion beam and the amount of current were improved as compared with Examples 1, 3 to 6, and Comparative Examples 1 to 3 of less than or exceeding 3.5.

1 lead electrode, 2 insulating layer, 2a one side, 2b other side, 3 acceleration electrode, 4, 4a, 4b multiple through-holes, 5 average length, 6 average opening diameter, 7 ground electrodes, 8 average pitch, 21 ion source, 22 ion generation chamber, 23 power supply, 24 plasma generation chamber, 25 gas supply unit, 26 confinement unit, 27 outlet, 28 ion measurement unit, 29 measurement substrate, 30 measurement probe, 31 ammeter, P plasma, I Cation.

Claims

An extraction electrode for extracting ions to form an ion beam,
An insulating layer made of an anodized film of a valve metal;
An accelerating electrode disposed on one surface of the insulating layer;
A plurality of through holes penetrating the acceleration electrode and the insulating layer in the thickness direction;
With
The extraction electrode whose aspect ratio which is ratio of the average length of the said through-hole, and an average opening diameter is 16-1000.
The extraction electrode according to claim 1, wherein the aspect ratio is 22 or more and 500 or less.
The lead electrode according to claim 1 or 2, wherein a ratio of an aperture ratio to an aspect ratio of the through hole is 1.0 or more and 3.5 or less.
The lead electrode according to any one of claims 1 to 3, wherein an average thickness of the insulating layer is 2 袖 m or more and 300 袖 m or less.
The extraction electrode according to any one of claims 1 to 4, wherein an aperture ratio by the through hole is 3% or more and 90% or less.
The lead electrode according to any one of claims 1 to 5, wherein an average opening diameter of the through holes is 30 nm or more and 50 µm or less.
A ground electrode disposed on the other surface opposite to the one surface of the insulating layer;
The lead electrode according to any one of claims 1 to 6, wherein the plurality of through holes penetrate the acceleration electrode, the insulating layer, and the ground electrode in a thickness direction.
An ion generation chamber for generating ions;
The extraction electrode according to any one of claims 1 to 7, disposed opposite the ion generation chamber,
An ion source having a power source for applying a potential to the extraction electrode;