JP5903864B2 - Ion milling equipment - Google Patents

Description

  The present invention relates to an ion milling apparatus that etches a workpiece by irradiating the workpiece with an ion beam.

As ion milling processing, a technique is known in which a workpiece such as a substrate is irradiated with an ion beam to ion-mill the surface, and an ion milling apparatus is used for this processing.
The ion milling apparatus has a structure in which plasma is generated in a plasma generation chamber, and an ion beam is extracted from the plasma generation chamber to a processing chamber in which a workpiece is disposed using an extraction electrode (see, for example, Patent Document 1). ).

JP 2010-118290 A

In a conventional ion milling apparatus, processing is performed by appropriately controlling the ion beam intensity in accordance with the material of the workpiece, the surface state after processing, and the like. In general, the ion beam intensity is set by adjusting the aperture ratio of the extraction hole for extracting the ion beam of the extraction electrode.
Thus, in the ion milling process, it is necessary to employ a lead electrode suitable for processing each workpiece.
However, after the extraction electrode is manufactured, it is difficult to finely adjust the processing profile such as the intensity of emitted ion beam and in-plane uniformity, and the manufactured extraction electrode has a problem that it is not versatile. .

  The present invention has been made to solve the above-described problems, and can be realized as the following forms or application examples.

  [Application Example 1] An ion milling apparatus according to this application example is provided with a filament that emits thermoelectrons as an ion source, a plasma generation chamber that has the filament and generates plasma, and a plurality of devices are arranged on the outer surface of the plasma generation chamber. A magnet, filament moving means for moving the filament toward or away from the magnet, a processing chamber communicating with the plasma generation chamber, and a drawer for extracting an ion beam from the plasma generation chamber to the processing chamber And an electrode.

According to this configuration, the filament moving means for moving the filament in a direction approaching or moving away from the multipolar magnets arranged on the outer surface of the plasma generation chamber is provided.
Charged particles such as thermoelectrons emitted from the filament undergo a circular motion (cyclotron motion) under the Lorentz force in a magnetic field formed by a multipolar magnet. By changing the filament position, it becomes possible to collect charged particles at an arbitrary location using cyclotron motion.
Thus, the plasma distribution of the plasma generated in the plasma generation chamber can be controlled, and the ion beam intensity and the processing profile by the ion beam can be easily adjusted even if the same extraction electrode is used.

  Application Example 2 In the ion milling apparatus according to the application example described above, it is preferable that the magnet is disposed at least on the outer surface of the plasma generation chamber orthogonal to the direction in which the ion beam is extracted.

According to this configuration, the magnet is disposed on the outer surface of the plasma generation chamber orthogonal to the direction in which the ion beam is extracted.
By arranging the magnets in this way, a magnetic field can be formed in the direction in which the ion beam is extracted, and it becomes easy to collect charged particles at an arbitrary location.

  Application Example 3 In the ion milling apparatus according to the application example described above, it is preferable that the magnet is formed in a rod shape and is arranged from a central portion of the outer surface of the plasma generation chamber toward an outer peripheral portion.

According to this configuration, the plurality of magnets are formed in a rod shape, and are arranged from the central portion of the outer surface of the plasma generation chamber toward the outer peripheral portion.
By arranging the magnets in this way, it is possible to collect charged particles in the central direction or the outer peripheral direction on the surface orthogonal to the direction in which the ion beam in the plasma generation chamber is drawn.

  Application Example 4 In the ion milling apparatus according to the application example described above, it is preferable that the filament is movable in a direction in which the ion beam is extracted and a direction intersecting the direction in which the ion beam is extracted.

According to this configuration, the filament can move in a direction toward and away from a direction perpendicular to the direction in which the ion beam is extracted, that is, the direction in which the ion beam is extracted from the plasma generation chamber. Furthermore, the filament can move in a direction that intersects the direction in which the ion beam is extracted, that is, a direction that approaches or moves away from the outer peripheral surface of the plasma generation chamber.
From this, the filament can be arbitrarily moved in the magnetic field formed by the magnet. Thus, the movement of charged particles can be controlled with high accuracy.

  Application Example 5 In the ion milling apparatus according to the application example described above, it is preferable that a plurality of the filaments are arranged, and each of the filaments can be moved independently by the filament moving means.

According to this configuration, a plurality of filaments are arranged, and each filament can be moved independently by the filament moving means.
From this, a plurality of filaments can be respectively arranged at arbitrary positions, and the movement of charged particles can be controlled with high accuracy.

The schematic diagram which shows the structure of the ion milling apparatus of 1st Embodiment. The schematic plan view which shows the magnet arrangement | positioning state of the plasma production chamber in 1st Embodiment. The schematic cross section which shows the magnet arrangement | positioning state of the plasma generation chamber in 1st Embodiment. The schematic diagram explaining operation | movement of a charged particle under a magnetic field. The plasma distribution map which simulated the plasma distribution in a plasma production chamber. The plasma distribution map which simulated the plasma distribution in a plasma production chamber.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. In the drawings used for the following description, the ratio of dimensions of each member is appropriately changed so that each member has a recognizable size.
(First embodiment)

<Configuration of ion milling device>
FIG. 1 is a schematic diagram showing the configuration of an ion milling apparatus.
In the following description, Cartesian coordinates are used, one direction of the plane of the apparatus is defined as the X-axis direction, the plane direction orthogonal to the X-axis is defined as the Z-axis direction, Called the axial direction, the positional relationship will be described.

The ion milling apparatus 1 covers a plasma generation chamber 10 that generates plasma, an extraction electrode 30 that extracts an ion beam from the plasma generation chamber 10, a processing chamber 40 into which the extracted ion beam is introduced, and the plasma generation chamber 10. A mechanism arrangement chamber 24 in which the filament moving mechanism 25 is arranged.
The plasma generation chamber 10 is formed in a cylindrical shape, and is disposed so that the cylindrical body 12 extends in the X-axis direction. One surface of the plasma generation chamber 10 orthogonal to the X-axis direction is opened and communicates with the processing chamber 40. A cylindrical flat surface portion 11 is formed on the other surface orthogonal to the X-axis direction of the plasma generation chamber 10.
Further, the plasma generation chamber 10 includes a gas inlet 16 through which a discharge gas such as argon (Ar) is supplied from the outside.

Inside the plasma generation chamber 10, a plurality of filaments 20 are provided as ion sources. The filament 20 is made of tungsten (W), for example, and emits thermoelectrons (charged particles) into the plasma generation chamber 10 by applying a voltage to the filament 20.
The filament 20 is connected to a filament moving mechanism 25 that allows the filament 20 to move within the plasma generation chamber 10.

The filament moving mechanism 25 is arranged in a mechanism arrangement chamber 24 formed so as to cover the plasma generation chamber 10, and includes a first linear stepping motor 26 and a second linear stepping motor 28.
The motor shaft 26a of the first linear stepping motor 26 can reciprocate in the Y-axis direction, and a second linear stepping motor 28 is fixed to the tip thereof. For this reason, the second linear stepping motor 28 can move in the Y-axis direction by the operation of the first linear stepping motor 26.
The motor shaft 28a of the second linear stepping motor 28 can reciprocate in the X-axis direction, and the filament 20 fixed to the filament mounting plate 21 is disposed at the tip thereof. For this reason, the filament 20 can move in the X-axis direction by the operation of the second linear stepping motor 28.
The motor shaft 28 a of the second linear stepping motor 28 is arranged such that the tip of the motor shaft 28 a is arranged in the plasma generation chamber 10 from the mechanism arrangement chamber 24 through the groove portion 15 of the cylindrical flat portion 11 of the plasma generation chamber 10. It is configured.

By using such a filament moving mechanism 25, the first linear stepping motor 26 can be operated to move the filament 20 in the Y axis direction within the plasma generation chamber 10, and the second linear stepping motor 28 can be operated. The filament 20 can be moved in the X-axis direction within the plasma generation chamber 10.
Each filament 20 can be independently moved to an arbitrary position by each filament moving mechanism 25.

In addition, multipolar magnets 13 and 14 are arranged on the outer periphery of the cylindrical flat surface portion 11 and the cylindrical body portion 12 of the plasma generation chamber 10.
FIG. 2 is a schematic plan view showing a magnet arrangement state in the plasma generation chamber, as viewed from the direction of arrow P (X-axis direction) in FIG. 3 is a schematic cross-sectional view taken along the line AA in FIG.
In addition, the arrow shown to the magnet in a figure has shown the direction where magnetic force goes within a magnet.

As shown in FIG. 2, a large number of magnets 13 a, 13 b, 13 c, and 13 d are arranged on the cylindrical plane portion 11 of the plasma generation chamber 10.
The magnets 13a, 13b, 13c, and 13d are formed in a rod shape, and four types of lengths are prepared. Hereinafter, each magnet will be described in the order of a long magnet.
The magnet 13 a is arranged so as to go from the central part of the cylindrical flat part 11 toward the outer peripheral part. Four magnets 13a are provided, and are arranged at intervals of 90 degrees from the center of the cylindrical plane portion 11 in the Y-axis direction and the Z-axis direction. The polarity that appears on the surface of the magnet 13a is configured to be the S pole.

The magnet 13b is sandwiched substantially in parallel from both sides with respect to one magnet 13a, and is disposed so as to go from the central portion of the cylindrical flat portion 11 toward the outer peripheral portion.
And the polarity which appeared on the surface of these eight magnets 13b is comprised so that it may become the N pole which becomes a polarity opposite to the adjacent magnet 13a.

The magnet 13c is disposed so as to be sandwiched substantially in parallel from the outside of the magnet 13b sandwiched from both sides with respect to one magnet 13a.
And the polarity which appeared on the surface of these eight magnets 13c is comprised so that it may become a south pole used as the polarity opposite to the adjacent magnet 13b.

The magnet 13d is disposed by sandwiching two magnets 13b sandwiched from both sides with respect to one magnet 13a and two magnets 13c from the outside in a substantially parallel manner.
And the polarity which appeared on the surface of these eight magnets 13d is comprised so that it may become a north pole used as the polarity opposite to the adjacent magnet 13c.
Thus, the adjacent magnets 13a, 13b, 13c, and 13d are arranged to be opposite poles. The magnets 13 a, 13 b, 13 c, and 13 d are arranged so as to be point symmetric with respect to the center of the cylindrical plane portion 11.

A large number of magnets 14 are disposed on the outer periphery of the cylindrical body 12 of the plasma generation chamber 10.
The magnet 14 is formed in a rod shape and is arranged so that the same pole appears on the surface in the X-axis direction (see FIG. 3), and the adjacent magnets are arranged so that the polarities are opposite in the circumferential direction.

  These magnets 13a, 13b, 13c, 13d, and 14 have a function of confining the plasma in the plasma generation chamber 10 by the lines of magnetic force and increasing the ionization rate by applying a magnetic field to the discharge region to increase the ion range. Have.

And the filament 20 is arrange | positioned between the magnet 13a and the magnet 13b in planar view shown in said FIG. The filament 20 is disposed in the plasma generation chamber 10 through a groove formed in the cylindrical flat surface portion 11 of the plasma generation chamber 10, but the groove is not shown in FIG.
As shown in FIG. 3, the filament 20 can move in the X-axis direction, can change the height dimension h from the inner surface of the cylindrical plane portion 11 of the plasma generation chamber 10, and approaches the inner surface of the cylindrical plane portion 11. And move away.
The filament 20 can also move in the Y-axis direction, and can move in a direction approaching and moving away from the cylindrical body 12 of the plasma generation chamber 10.

The filament 20 is connected to a filament power source (not shown), and a predetermined voltage is applied from the filament power source. The plasma generation chamber 10 is connected to the positive electrode side of an arc power source (not shown), and the negative electrode side is connected to the positive electrode side of the filament power source to apply an arc voltage.
The discharge gas such as Ar supplied is ionized by the discharge between the negative terminal of the filament 20 and the inner wall serving as the anode of the plasma generation chamber 10.

Returning to FIG. 1, the extraction electrode 30 is disposed between the plasma generation chamber 10 and the processing chamber 40.
The extraction electrode 30 is composed of three electrodes: an acceleration electrode 30a, a deceleration electrode 30b, and a ground electrode 30c. The acceleration electrode 30a, the deceleration electrode 30b, and the ground electrode 30c are arranged in this order from the side closer to the plasma generation chamber 10, and are fixed to the electrode mounting plate 31. Each electrode is formed in a disk shape, and a high melting point material such as molybdenum is used. A large number of extraction holes 32a, 32b, and 32c through which the ion beam passes are provided in the disks of the electrodes.

A positive voltage of an acceleration power source (not shown) is connected to the acceleration electrode 30a and a positive voltage is applied. Further, the positive electrode side of the acceleration power source is connected to the positive electrode side of the arc power source through a resistor, and the negative electrode side is grounded.
A negative electrode of a deceleration power source (not shown) is connected to the deceleration electrode 30b to apply a negative voltage, and the positive electrode side of the deceleration power source is grounded.
The ground electrode 30c is grounded or a voltage less than −100V is applied to the ground.
The energy of the ion beam irradiated from the extraction electrode 30 can be adjusted by adjusting the voltage applied to the acceleration electrode 30a and the deceleration electrode 30b.

A microwave plasma neutralizer 50 is disposed in the processing chamber 40.
The microwave plasma neutralizer 50 generates plasma by microwave discharge downstream of the extraction electrode 30. The plasma generated by the microwave discharge is used as an electron supply source for preventing the surface of a workpiece such as a substrate from being charged with an ion beam.

An exhaust device (not shown) is connected to the processing chamber 40, and the processing chamber 40, the plasma generation chamber 10 and the mechanism arrangement chamber 24 connected to the processing chamber 40 can be kept in a reduced pressure state.
The processing chamber 40 is provided with a substrate holder 41 that holds a workpiece such as a substrate of the workpiece. The substrate holder 41 is formed in a disc shape, and a shaft is provided at the center of the substrate holder 41 so as to be rotatable about the shaft. In addition, the substrate holder 41 is arranged to be inclined with respect to the irradiated ion beam in accordance with the processing speed of the workpiece.

Further, a shutter 52 may be provided between the extraction electrode 30 and the substrate holder 41.
The shutter 52 is opened and closed by a shutter driving device 53. The shutter 52 is opened when the workpiece held by the substrate holder 41 is irradiated with an ion beam, and when the ion beam is not irradiated, the shutter 52 is closed and the ion beam is irradiated. Can be controlled.
The processing chamber 40 is electrically grounded to ensure the stability of ion beam introduction.

<Operation of ion milling device>
Next, operation | movement of said ion milling apparatus 1 is demonstrated.
The processing chamber 40, the plasma generation chamber 10, and the mechanism arrangement chamber 24 are evacuated by the exhaust device, and then a constant flow rate of discharge gas is supplied to the plasma generation chamber 10.
Plasma is generated in the plasma generation chamber 10 by the discharge between the negative terminal of the filament 20 and the inner wall serving as the anode of the plasma generation chamber 10. The generated plasma ions are extracted from the plasma generation chamber 10 to the processing chamber 40 by the extraction electrode 30.
Next, the shutter driving device 53 is actuated to open the shutter 52, and the ion beam introduced into the processing chamber 40 is irradiated onto the workpiece held by the rotating substrate holder 41 to perform ion milling.

Here, the effect | action and effect of changing the position of the filament 20 in the plasma production chamber characteristic in this embodiment are demonstrated.
FIG. 4 is a schematic diagram illustrating the operation of charged particles under a magnetic field.

As shown in FIG. 4A, when the magnetic field B is uniform and the charged particle e ⁻ is not subjected to an external force other than the force from the magnetic field B, the charged particle e ⁻ receives the Lorentz force from the magnetic field B. A circular motion with a radius r is performed in a plane perpendicular to the magnetic field B. Such circular motion of charged particles in a magnetic field is called cyclotron motion. In this way, the individual charged particles that make up the plasma perform a cyclotron motion in a magnetic field.
However, when an external force other than the magnetic field B is applied to the charged particle e ⁻ or when the magnetic field B is not uniform, the center of the circular motion also moves in a direction perpendicular to the magnetic field B, and the charged particle moves in a spiral motion. I do. This phenomenon is called drift.

Further, when magnets having different polarities are arranged at intervals, a magnetic field B as shown in FIG. 4B is formed.
At this time, in the region F far from the magnet, the density of the magnetic field B is coarse, and the radius r of the cyclotron motion increases. On the other hand, in the region G near the magnet, the density of the magnetic field B is dense and the radius r of the cyclotron motion is small.

Using such a phenomenon (drift) between a magnetic field and charged particles, it is possible to control charged particles.
For example, consider the case where three magnets 13a, 13b ₁ and 13b ₂ are arranged on a flat plate in parallel with each other as shown in FIG.
Magnet 13b ₁ and the magnet 13b ₂ are arranged so that the upper surface becomes the N pole, the magnets 13a sandwiched magnet 13b ₁ and the magnet 13b ₂ are arranged so that the upper surface becomes the S pole.
In such a magnet arrangement, the magnetic field B is formed from the north pole to the south pole. As shown in FIG. 4B, the magnetic field B is formed from a location close to the magnet to a range where the magnetic force reaches.

Here, the charged particles e relatively close magnetic field B from the magnet 13b ₁ and the magnet 13a ^- when has the jumped, charged particles e ^- direction of the front side of the drawing under the force and the external force from the magnetic field B (arrow 17 ) Move with spiral motion.
Also, charged particles e relatively close magnetic field B from the magnet 13a and the magnet 13b ₂ ^- when has the jumped, charged particles e ^- the back side (the direction of the arrow 18) of the drawing under the force and the external force from the magnetic field B Move with spiral motion.
As described above, the charged particles e ⁻ can be collected at an arbitrary place by the drift of the charged particles e ⁻ . In order to promote the behavior of such charged particles e ⁻ , the position of the filament 20 may be changed to change the positional relationship between the magnetic field B and the charged particles.

Next, an example of the simulation result of the plasma distribution according to the filament position in the plasma generation chamber is shown. This simulation was performed using an electronic orbit simulation apparatus. In this simulation, only the height dimension h from the inner surface of the cylindrical plane portion of the plasma generation chamber to the filament is changed.
FIG. 5 shows the plasma distribution when the height h from the inner surface of the cylindrical flat portion of the plasma generation chamber is 100 mm. FIG. 6 shows the plasma distribution when the height dimension h from the inner surface of the cylindrical flat portion of the plasma generation chamber is 40 mm.

5 and 6, (a) is a view of the cross section of the plasma generation chamber, corresponding to FIG. 3, and (b) is a view of the plasma generation chamber as viewed from the processing chamber side.
And what appears white in the figure is a dense part of plasma (charged particles).

  As shown in FIG. 5, when the height dimension h from the inner surface of the cylindrical plane portion of the plasma generation chamber is 100 mm, it can be seen that the plasma is distributed almost uniformly. That is, the thermoelectrons emitted from the filament and the charged particles ionized from the discharge gas are distributed substantially uniformly in the height dimension h direction and the plane direction of the plasma generation chamber.

On the other hand, as shown in FIG. 6, when the height dimension h from the inner surface of the cylindrical plane portion of the plasma generation chamber is 40 mm, it can be seen that the plasma moves and is confined locally. That is, in the height dimension h direction, it is distributed in a portion close to the cylindrical plane portion of the plasma generation chamber, and in the plane direction, as shown in FIG. Plasma is distributed on the part side.
It is possible to change the plasma distribution not only by changing the height dimension h, but also by moving the filament to the center or outer periphery of the plasma generation chamber.
Thus, the plasma distribution can be controlled by appropriately selecting the arrangement of the magnet and the position of the filament.

As described above, the ion milling apparatus 1 of the present embodiment includes the filament moving mechanism 25 that moves the filament 20 in the approaching or moving away direction with respect to the multipolar magnets 13a to 13d arranged on the outer surface of the plasma generation chamber 10. I have.
By changing the position of the filament 20, it becomes possible to collect charged particles at an arbitrary location using the drift of charged particles.
Thus, the distribution of plasma generated in the plasma generation chamber 10 can be controlled, and the ion beam intensity and the processing profile by the ion beam can be adjusted.
For example, by changing the position of the filament 20 without exchanging the extraction electrode 30 for drawing out the ion beam, it is possible to adjust the ion beam intensity and obtain a processing profile suitable for the workpiece.

Further, the magnets 13a to 13d are disposed on the cylindrical plane portion 11 of the plasma generation chamber 10 that is orthogonal to the direction in which the ion beam is extracted. Further, the plurality of magnets 13 a to 13 d are formed in a rod shape, and are arranged from the central portion of the cylindrical flat portion 11 of the plasma generation chamber 10 toward the outer peripheral portion.
By arranging the magnets 13a to 13d in this manner, a magnetic field can be formed in the direction in which the ion beam is extracted, and it becomes easy to collect charged particles at an arbitrary place. Moreover, it is possible to collect charged particles at the central portion or the outer peripheral portion on a plane orthogonal to the direction in which the ion beam of the plasma generation chamber 10 is extracted.

Further, the filament 20 can move in a direction toward and away from a direction in which the ion beam is extracted, that is, a plane orthogonal to the direction in which the ion beam in the plasma generation chamber 10 is extracted. Furthermore, the filament 20 can move in a direction intersecting with the direction in which the ion beam is extracted, that is, in a direction approaching and moving away from the outer peripheral surface of the plasma generation chamber 10.
From this, the filament 20 can be arbitrarily moved in the magnetic field formed by the magnet, and the movement of the charged particles can be controlled with high accuracy.

Further, a plurality of filaments 20 are arranged, and each filament 20 can be moved independently by a filament moving mechanism 25.
Thus, the plurality of filaments 20 can be arranged at arbitrary positions, and the movement of charged particles can be controlled with high accuracy.

In the ion milling apparatus according to the present embodiment, the processing conditions and the like are obtained by processing and matching the workpiece. However, the current density is measured and fed back by the Faraday cup provided on the substrate holder for detecting charged particles. You may take a method.
By arranging a plurality of Faraday cups that measure the current density of the ion beam at a narrow pitch on the substrate holder, it is possible to improve processing accuracy and reliability.
In feedback control, a control system may be constructed by associating the relationship between the ion beam current density and the ion milling rate, the relationship between the filament current and the magnetic field, and the like based on data measured in advance.

Moreover, although embodiment which performs ion milling was described in 1st Embodiment, it is also possible to perform surface treatments, such as a hydrophilic process of a substrate surface, and a water repellent process, using this ion milling apparatus 1. FIG.
As described above, the ion milling apparatus 1 described in the first embodiment is specifically used as an apparatus for planarizing a substrate by ion milling the substrate, a surface treatment apparatus, a frequency adjustment apparatus for a piezoelectric element, and the like. Can do.

  The present invention is not limited to the embodiment described above, and the specific structure and procedure for carrying out the present invention can be appropriately changed to other structures and the like as long as the object of the present invention can be achieved. it can. Many modifications can be made by those skilled in the art within the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Ion milling apparatus, 10 ... Plasma generation chamber, 11 ... Cylindrical plane part, 12 ... Cylindrical trunk | drum, 13 ... Magnet, 14 ... Magnet, 15 ... Groove part, 16 ... Gas inlet, 20 ... Filament, 21 ... Filament attachment Plate 24, mechanism arrangement chamber 25, filament moving mechanism as filament moving means 26, first linear stepping motor 26 a, motor shaft 28, second linear stepping motor 28 a motor shaft 30, extraction electrode 30a ... Acceleration electrode, 30b ... Deceleration electrode, 30c ... Ground electrode, 31 ... Electrode mounting plate, 32a, 32b, 32c ... Lead-out hole, 40 ... Processing chamber, 41 ... Substrate holder, 50 ... Microwave plasma neutralizer, 52 ... Shutter, 53 ... shutter driving device.

Claims (4)

A filament that emits thermoelectrons as an ion source;
A plasma generation chamber having the filament and generating plasma;
A plurality of magnets disposed on the outer surface of the plasma generation chamber;
Filament moving means for moving the filament in a direction approaching or moving away from the magnet;
A processing chamber communicating with the plasma generation chamber;
An extraction electrode for extracting an ion beam from the plasma generation chamber to the processing chamber;
Equipped with a,
The filament has a direction in which the ion beam is drawn, and the ion beam
An ion milling apparatus, characterized in that the ion milling apparatus is movable in a direction intersecting with a direction of being drawn out . In the ion milling device according to claim 1,
The ion milling apparatus, wherein the magnet is disposed at least on an outer surface of the plasma generation chamber orthogonal to a direction in which the ion beam is extracted. In the ion milling device according to claim 2,
The ion milling apparatus, wherein the magnet is formed in a rod shape and is arranged from a central portion of the outer surface of the plasma generation chamber toward an outer peripheral portion. In the ion milling device according to any one of claims 1 to 3 ,
An ion milling apparatus, wherein a plurality of the filaments are arranged, and each of the filaments can be moved independently by the filament moving means.

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