Ion milling apparatus and processing method using the same

Abstract

A sample stage (104), which can be inclined about an inclination axis (T), causes a sample (106) to rotate about a sample rotation axis (C) orthogonal to the inclination axis (T), and a plurality of ion sources (101, 107, 110) are adjusted by ion source moving mechanisms (102, 108, 111) to which the ion sources (101, 107, 110) are attached so that the degrees of eccentricity will be different from each other, the degree of eccentricity being the distance on the sample surface between the center axis of the ion beam and the sample rotation axis (C). A control unit (113) radiates non-focused ion beams from the plurality of ion sources (101, 107, 110) toward the sample being rotated about the sample rotation axis (C) by the sample stage (104), whereby milling is performed.

Description

[Technical Field]

[0001] The present invention relates to an ion milling apparatus and a processing method using the same. [Background technology]

[0002] Ion milling equipment irradiates a sample (e.g., metal, semiconductor, glass, ceramic, etc.) that is to be observed with an electron microscope with an unfocused ion beam. By sputtering, atoms are knocked off the sample surface, allowing for stress-free polishing of the sample surface or exposure of the sample's internal structure. The sample surface ion-milled by ion beam irradiation, or the exposed internal structure of the sample, becomes the observation surface for scanning electron microscopes and transmission electron microscopes.

[0003] Patent Document 1 discloses an invention relating to an ion milling apparatus that can achieve both high processing accuracy, a wide processing area, and smoothness of the processed surface through processing using multiple ion beams. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2021 / 152726 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Patent Document 1 describes a technique for cross-sectional milling, in which a mask is placed on the sample to shield it from an ion beam, and the portion of the sample protruding from the mask is milled. In contrast, a method of processing the sample surface by irradiating it with an ion beam while rotating the sample is called planar milling. When planar milling is used, for example, to remove polishing scratches from the sample surface, the ion beam's central axis and the stage's sample rotation axis are eccentric, and the ion beam is irradiated while the sample is rotating. The half-width of the irradiated ion beam profile is usually about 0.5 to 1 mm. In this case, since the strongest part, near the center of the ion beam, is not continuously irradiated to one spot on the sample surface, a smooth sample surface can be obtained over a wide area. Depending on the amount of eccentricity, it is possible to smooth an area up to about twice the beam diameter.

[0006] Planar milling has a wide range of applications, including removing polishing scratches from sample surfaces and delayering semiconductors, particularly three-dimensional devices in which memory cell arrays are stacked. However, in recent years, the development of larger three-dimensional devices has progressed, leading to an increased demand for processing over a wider range than before. [Means for solving the problem]

[0007] An ion milling apparatus according to one embodiment of the present invention comprises a sample chamber, a sample stage located in the sample chamber and on which a sample holder with a sample set in it is mounted, a plurality of ion sources attached to the sample chamber via an ion source movable mechanism, and a control unit. The sample stage is tiltable about a tilt axis, and the sample is rotated about a sample rotation axis perpendicular to the tilt axis. The plurality of ion sources are adjusted by an ion source movable mechanism to which the ion sources are attached so that the eccentricity, which is the distance between the ion beam central axis on the sample surface and the sample rotation axis, is different from that of the plurality of ion sources. The control unit performs milling by irradiating the sample, which is rotated about the sample rotation axis by the sample stage, with unfocused ion beams from the plurality of ion sources. [Effects of the Invention]

[0008] Provided are an ion milling apparatus and a processing method capable of planar milling a wide range while reducing thermal damage to a sample. Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Brief Description of the Drawings

[0009] [Figure 1A] It is a configuration example (top view) of the ion milling apparatus of Example 1. [Figure 1B] It is a configuration example (side view) of the ion milling apparatus of Example 1. [Figure 2A] It is a schematic diagram showing an ion source and a power supply circuit for applying a control voltage to the ion source. [Figure 2B] It is a diagram showing the processing shape when processing a sample with one ion source while changing the amount of eccentricity. [Figure 3] It is a schematic diagram showing a state where an ion beam is irradiated from a plurality of ion sources to a sample. [Figure 4A] It is a schematic diagram showing the arrangement of ion sources three-dimensionally. [Figure 4B] It is a diagram for explaining a method of setting the amount of eccentricity for the i-th ion source. [Figure 5] It is a flowchart showing a series of operations from sample setting to the end of processing. [Figure 6] It is a configuration example (top view) of the ion milling apparatus of Example 2. [Figure 7] It is a diagram for explaining a method of adjusting the amount of eccentricity of an ion source.

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described based on the drawings.

Examples

[0011] Figures 1A and 1B are schematic diagrams showing the main parts of the ion milling apparatus 100 of Example 1. Figure 1A is a top view, and Figure 1B is a side view. The ion milling apparatus 100 mainly consists of a sample stage 104 for placing a sample 106 to be processed in a sample chamber 114, and a plurality of ion sources. Here, an example with three ion sources 101, 107, and 110 is shown. The sample stage 104 can be tilted about an inclination axis T and has a sample rotation axis C that is perpendicular to the inclination axis T. A sample holder 105 with the sample 106 set in it is mounted on the sample stage 104. Figures 1A and 1B also show the coordinate system (X axis, Y axis, Z axis) of the sample stage. In this example, the inclination axis T extends in the X-axis direction, the ion beam central axes of the plurality of ion sources are parallel to the XZ plane, and the sample rotation axis C extends in the Y-axis direction.

[0012] The three ion sources 101, 107, and 110 are attached to the sample chamber 114 via ion source movable mechanisms 102, 108, and 111, respectively. The extension direction of the ion beam central axis of the i-th ion source (i=1~3) is Z i Using Z as the axis, i X perpendicular to the axis i Y i When defining the plane, the i-th ion source movable mechanism is such that the i-th ion source is X i Axis direction, Y i Axial, Z i It can be moved in the axial direction. In this example, the coordinate system (X1 axis, Y1 axis, Z1 axis) of the first ion source movable mechanism 102 is aligned with the coordinate system (X axis, Y axis, Z axis) of the sample stage.

[0013] The three ion sources 101, 107, and 110 have their ion beams aligned along their central axis, i.e., Z. i The axes can be adjusted so that they intersect at a single point at the intersection of the surface of sample 106 and the sample rotation axis C. At this time, the three ion sources are positioned such that the angle between the Z1 axis and the Z2 axis is 45°, and the angle between the Z1 axis and the Z3 axis is -45°.

[0014] A first high-voltage power supply 103 for applying a control voltage for generating an ion beam is connected to the first ion source 101, a second high-voltage power supply 109 for applying a control voltage for generating an ion beam is connected to the second ion source 107, and a third high-voltage power supply 112 for applying a control voltage for generating an ion beam is connected to the third ion source 110. Also, the high-voltage power supplies 103, 109, 112 are controlled by a control unit 113. The control unit 113 is connected to a control section 118. The control section 118 is, for example, a PC (Personal Computer), which controls the entire device and executes milling processing by the device.

[0015] Also, a vacuum pump 115 capable of evacuating the pressure in the sample chamber 114 to a high vacuum (1.0 × 10 -3 Pa or less) is connected to the sample chamber 114. Further, as shown in Fig. 1B, an image sensor 116 for observing the processed shape of the sample 106 from above is provided. The image sensor 116 is preferably configured to capture an enlarged image of the processed shape of the sample 106 by an optical microscope or the like.

[0016] When an ion milling device is used as a pretreatment device for observing the sample surface or sample cross-section with a scanning electron microscope or a transmission electron microscope, the Penning method, which is effective for miniaturization of the device, is often adopted for the ion source. In this embodiment as well, the Penning method is adopted for the ion sources 101, 107, 110. Although details will be described later, in the Penning type ion source, a high voltage (control voltage) is applied from the high-voltage power supply to the internal electrode to cause Penning discharge to generate electrons, and the generated electrons are collided with argon gas supplied from the outside to generate argon ions. The ion source irradiates the sample 106 set on the sample holder 105 with the argon ions thus generated as a non-focused ion beam.

[0017] The central axes of the ion beams emitted from the first ion source 101, the second ion source 107, and the third ion source 110 intersect at a single point on the sample rotation axis C of the sample stage 104. This point is the intersection of the inclination axis T of the sample stage 104 and the sample rotation axis C, and is the eucentric position. Each ion source has its own ion beam central axis Z i Using the position where X passes through the eucentric position as a reference, the i-th ion source movable mechanism is used, i Axis direction, Y i Axial, Z i It is designed to be movable in three axial directions. The sample chamber 114 is kept under high vacuum by the vacuum pump 115, allowing a stable ion beam to be irradiated onto the sample without being affected by the gas in the sample chamber 114. At this time, the sample stage 104 rotates the sample 106 around the sample rotation axis C.

[0018] Figure 2A is a schematic diagram showing the first ion source 101 and the first high-voltage power supply 103 employing the Penning method. In the figure, the power supply circuit that applies the control voltage to the electrode components of the first ion source 101 is extracted and shown from the first high-voltage power supply 103. The second ion source 107 and the third ion source 110 have the same configuration as the first ion source 101, so their explanation is omitted.

[0019] The ion source 101 has as its main components a first cathode 201, a second cathode 202, an anode 203, a permanent magnet 204, an accelerating electrode 205, a gas pipe 206, and a gas flow control unit 207. To generate an ion beam, argon gas is injected into the ion source 101 through the gas pipe 206. Inside the ion source 101, the first cathode 201 and the second cathode 202 are arranged opposite each other via the permanent magnet 204 and are at the same potential, with the anode 203 positioned between the first cathode 201 and the second cathode 202. Electrons are generated when a discharge voltage Vd is applied from the high-voltage power supply 103 between the cathodes 201, 202 and the anode 203. The Lorentz force acts on the generated electrons due to the permanent magnet 204 placed inside the ion source 101, causing the electrons to undergo helical motion. The gas flow control unit 207 controls the flow rate, and argon gas injected from the gas pipe 206 collides with electrons to form a plasma, generating argon ions. An acceleration voltage Va is applied between the anode 203 and the accelerating electrode 205 from the high-voltage power supply 103, and the generated argon ions are extracted by the accelerating electrode 205 and emitted as an ion beam.

[0020] Figure 2B shows the processed shape when a sample is processed with a single ion source while varying the eccentricity (the distance between the sample rotation axis C and the ion beam central axis Z on the sample surface). The horizontal axis represents the processing width [mm], and the vertical axis represents the processing depth [μm]. The sample rotation axis C is at the 0 position on the horizontal axis. The ion beam profile from the ion source generally follows a Gaussian distribution. Therefore, when the eccentricity is 0, i.e., when the sample rotation axis C and the ion beam central axis Z coincide, the processed shape follows the beam profile. In contrast, by eccentricating the sample rotation axis C and the ion beam central axis Z, the area of ​​planar milling is expanded, and a processed shape with a flat surface is obtained. For example, when the eccentricity is 2.0 mm, it can be seen that a flat surface is formed around the position of the sample rotation axis C. However, as the eccentricity is further increased, the area of ​​planar milling is further expanded, but the flat surface is lost from the processed shape. For example, when the eccentricity is 3.0 mm, it can be seen that a convex surface is formed with the position of the sample rotation axis C as its apex.

[0021] Figure 2B shows that a flat surface can be obtained by performing planar milling with the sample rotation axis C and the ion beam central axis Z eccentrically. However, the amount of eccentricity required to obtain a flat surface is limited, indicating that there are limitations to the depth and width of the flat surface obtained by planar milling. The depth and width of the flat surface can also be adjusted by adjusting parameters such as the ion beam profile, irradiation angle (amount of inclination around the inclination axis T), and processing time. However, for example, if the processing time, i.e., the milling time, is long, there is a risk of damaging the sample due to heat generated by beam irradiation.

[0022] Therefore, in this embodiment, planar milling is performed using a plurality of ion sources with different amounts of eccentricity. With this configuration, the degree of freedom in setting the conditions of the ion milling apparatus with respect to the specifications of the processed shape regarding the depth and width of the flat surface can be increased. For example, one of the plurality of ion sources irradiates the sample with an ion beam with an eccentricity that forms a convex surface having the position of the sample rotation axis C as the apex, and the other irradiates the sample with an ion beam with an eccentricity that forms a concave surface having the position of the sample rotation axis C as the bottom, thereby making it possible to flatten the processed shape. Moreover, in this case, by processing using a plurality of ion sources, the milling time can be shortened, and thus the thermal damage to the sample can be reduced.

[0023] FIG. 3 is a schematic diagram showing a state in which the sample 106 is irradiated with ion beams from three ion sources. Since the three ion sources are arranged at 45° intervals, the ion beam central axes Z2 and Z3 are inclined toward the ion beam central axis Z1, respectively. However, for clarity of illustration, these ion beam central axes are shown parallel. In FIGS. 1A and 1B, the state (initial state) in which the ion beams irradiated from each ion source intersect at a point on the sample rotation axis C is shown. By moving the ion source movable mechanism to which the ion source is attached, it is possible to provide an eccentricity d. Let the eccentricity of the first ion source 101 be d1, the ion beam diameter on the surface of the sample 106 be φ1, the eccentricity of the second ion source 107 be d2, the ion beam diameter on the surface of the sample 106 be φ2, the eccentricity of the third ion source 110 be d3, and the ion beam diameter on the surface of the sample 106 be φ3, and d1 < d2 < d3. For ease of understanding the positional relationship of the ion beams, in FIG. 3, the ion beam from the second ion source 107 is also shown at a position symmetric with respect to the sample rotation axis C.

[0024] In this case, the diameter R of the planar milling processing range is R = 2d3 + φ3, and at this time, it is recommended that any of the following inequalities (Equation 1) to (Equation 6) be satisfied. d1 < φ1 / 2 (Equation 1) φ1 / 2 < d2 - d1 (Equation 2) φ2 / 2 < d2 - d1 (Equation 3) φ2 / 2 < d3 - d2 (Equation 4) φ3 / 2 < d3 - d2 (Equation 5) d3 - d2 < d2 - d1 (Equation 6) By satisfying (Equations 1) to (Equation 5), the ion beam is irradiated over the entire range of the diameter R of the planar milling machining range. Also, as the eccentricity d increases, the incident angle of the ion beam with respect to the sample surface increases, resulting in a decrease in the ion beam irradiation amount per unit time. Therefore, there is a risk that the variation in the machining depth Δh becomes large outside the planar milling machining range, or in other words, the flatness of the machining shape is lost. Thus, when performing planar milling machining using three or more ion sources, in order to make the beam irradiation amount per unit time as uniform as possible, as the eccentricity increases, the overlapping amount with the ion beam from the ion source adjacent to the inner side should be made as large as possible, that is, it is desirable to set the eccentricity that satisfies (Equation 6).

[0025] Fig. 4A is a schematic diagram showing the three-dimensional arrangement of the i-th (i = 1 to 3) ion sources (101, 107, 110) in Figs. 1A and 1B. The X i axis, Y i axis, and Z i axis of the i-th ion source movable mechanism (102, 108, 111) are in the initial positions, and the Z i axis (i = 1 to 3) intersects the sample rotation axis C at a single point (initial state). Also, the three ion sources are on the same plane (XZ plane), and the distances (W.D. (Working Distance)) from the intersection point on the sample rotation axis C to the ion sources are all the same value. By moving the X i axis of each ion source by s and the Y i axis by t, the eccentricity d i from the sample rotation axis C can be set. At this time, as shown in the schematic diagram when viewed from the Z i axis for the i-th ion source in Fig. 4B, the eccentricity d i =(s 2 +t 2 ) 1 / 2 is satisfied. Note that this calculation formula is for the state where the sample 106 is tilted about the tilt axis T so that the i-th ion source and the sample 106 face each other. However, the tilt of the tilt axis T and the Z with respect to the normal direction of the sample surfacei Even if the tilt of the axis is arbitrary, geometrically, including these angles, d i It goes without saying that we can calculate its size.

[0026] The ion source movable mechanisms 102, 108, and 111 may be manually operated, or each axis of each movable mechanism may be equipped with a drive motor for automatic control. In the case of automatic control, for example, each drive motor is connected to the control unit 113, and the amount of movement of each axis can be input from the control unit 118 to the control unit 113.

[0027] Figure 5 is a flowchart showing the sequence of operations of the ion milling apparatus 100 from sample setting to completion. Details of each operation are as follows.

[0028] S301: The sample holder 105, which contains sample 106, is placed on the sample stage 104.

[0029] S302: The sample chamber 114 is evacuated using the vacuum pump 115 until it reaches a high vacuum.

[0030] S303: The first ion source movable mechanism 102, the second ion source movable mechanism 108, and the third ion source movable mechanism 111 control the eccentricity d of each ion source with respect to the sample rotation axis C. i Adjust the plane milling range. Specifically, the ion beam diameter at the sample surface of the i-th ion source (i=1~3) is set to φ i In this case, the eccentricity d satisfies the desired planar milling range diameter R and satisfies the above-mentioned equations (1) to (6). i Set the eccentricity d i The i-th ion source is moved accordingly by the i-th ion source movable mechanism.

[0031] S304: Processing conditions are set for the first ion source 101, the second ion source 107, and the third ion source 110. The processing conditions include the ion beam diameter φ of the ion beam from the ion source at the sample surface. Since the ion beam diameter is determined by the profile of the ion beam emitted by the ion source, it can be specifically controlled by the acceleration voltage Va, discharge voltage Vd, etc.

[0032] An example of a method for measuring the ion beam diameter φ is described below. For example, in the case of the first ion source 101 in Figure 1A, a conductive needle-shaped measuring probe (e.g., a carbon measuring probe) with the smallest possible diameter is held so that its longitudinal direction is the Y-axis, and moved in the X-axis direction in the XY plane including the inclination axis T. The ion beam diameter φ can be measured by plotting the relationship between the position of the measuring probe in the X-axis direction and the ion beam current flowing through the measuring probe. It is advisable to store in the control unit 118 the ion beam diameter φ and / or ion beam current measured according to the above measurement method while changing the ion beam irradiation conditions, so that the ion source can be set to irradiate an ion beam with a desired ion beam diameter φ.

[0033] The processing conditions include the irradiation conditions for the ion beam of each ion source, and the irradiation conditions include the discharge voltage Vd applied from the high-voltage circuit, the acceleration voltage Va, and the gas flow rate controlled by the gas flow rate control unit 207. As described above, if the relationship between the ion beam diameter φ and / or ion beam current and the irradiation conditions is registered in the control unit 118, the control unit 118 can automatically determine the irradiation conditions such as the acceleration voltage Va and discharge voltage Vd based on the registered relationship according to the ion beam diameter φ and / or ion beam current set in the control unit 118, and set the irradiation conditions for the ion beam of each ion source in the control unit 113.

[0034] S305: Start sample processing.

[0035] S306: Check if the processing is sufficient. For example, if a processing time is set in the processing conditions set in step S304, follow that setting. Here, we will explain an example of making a judgment using an image sensor 116 that observes the processed shape from above. The judgment is made according to the image of the planar milling processing area centered on the sample rotation axis C captured by the image sensor 116. For example, if the sample 106 has a laminated film structure made of stacked different materials, the color of the layer exposed by planar milling will differ depending on the material. Therefore, it is determined whether the color of the image of the planar milling processing area centered on the sample rotation axis C captured by the image sensor 116 is the color of the layer to be exposed by planar milling. If the processing is insufficient, for example, if a part of the planar milling processing area is not the color of the layer to be exposed, return to step S303 and adjust the eccentricity of each ion source so that processing of the unexposed part proceeds preferentially. If the processing is sufficient, that is, if the entire planar milling processing area is the color of the layer to be exposed, proceed to step S307 and end the processing. The determination can be made visually, or the control unit 118 can use image processing from the image of the sample acquired by the image sensor 116 to identify the planar milling area, determine the state of the exposed color, and then automatically perform a completion determination and eccentricity adjustment. [Examples]

[0036] Figure 6 is a schematic diagram showing the main parts of the ion milling apparatus 100b of Example 2. Components common to Example 1 are denoted by the same reference numerals. In Example 2, each ion source is attached to the sample chamber 114b without a movable mechanism, and a sample height adjustment mechanism 117 is provided on the sample holder 105. The sample height adjustment mechanism 117 is controlled by the control unit 113. The sample height adjustment mechanism 117 may also be configured for manual control.

[0037] The three ion sources 101, 107, and 110 have their ion beams aligned along their central axis, i.e., Z. iThe axes are mounted so that they intersect at a single point at the intersection of the surface of sample 106 and the sample rotation axis C. At this time, the three ion sources are arranged such that the angle between the Z1 axis and the Z2 axis is θ2, and the angle between the Z1 axis and the Z3 axis is θ3.

[0038] Figure 7 shows the eccentricity d of the ion source. i This is a schematic diagram showing the adjustment method. Here, the sample 106 is tilted around the tilt axis T so that the first ion source 101 and the sample 106 face each other. The ion beams irradiated from each ion source intersect at a certain point on the sample rotation axis C, but by adjusting the sample height with the sample height adjustment mechanism 117, the sample surface is moved away from the intersection point of the ion beams, and the same effect as when the ion source is eccentric is obtained. As described above, the angle between the Z1 axis and the Z2 axis is θ2, and the angle between the Z1 axis and the Z3 axis is θ3, so the eccentricity of the second and third ion sources (the distance between the sample rotation axis C and the ion beam center axis Z on the sample surface) will be a different value.

[0039] In Figure 7, the ion sources are arranged on the same plane (XZ plane), but they do not necessarily have to be on the same plane. However, it is desirable that the distance (WD) from the intersection of the ion beam central axis Z on the sample rotation axis C to each ion source is the same.

[0040] When the sample height is changed by ΔZ from the intersection of the ion beam central axis Z on the sample rotation axis C, let d2 be the eccentricity of the second ion source and d3 be the eccentricity of the third ion source. Then d2 and d3 are given by (Equation 7) and (Equation 8) shown below. d² = ΔZtanθ² (Equation 7) d3 = ΔZtanθ3 (Equation 8) The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments and modifications described above are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment or modification with the configuration of another embodiment or modification, and it is also possible to add the configuration of another embodiment or modification to the configuration of one embodiment or modification. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment or modification with other configurations.

[0041] For example, although the number of ion sources was described as three in each example, it is not a problem if there are two or four or more. In the initial state of Example 1 and Example 2, examples were shown where all ion sources are on the same plane (XZ plane), but the Z of the ion sources i It is not a problem if the axes do not lie on the same plane, as long as they intersect at a single point on the sample rotation axis C. Furthermore, although the ion source was fixed in Example 2, it may be provided via an angle tilting mechanism that allows for free angle tilting while ensuring sufficient WD relative to the sample. This increases the degree of freedom in determining the magnitude of eccentricity applied to each ion source. [Explanation of Symbols]

[0042] 100,100b: Ion milling apparatus, 101: First ion source, 102: First ion source movable mechanism, 103: First high-voltage power supply, 104: Sample stage, 105: Sample holder, 106: Sample, 107: Second ion source, 108: Second ion source movable mechanism, 109: Second high-voltage power supply, 110: Third ion source, 111: Third ion source movable mechanism, 112: Third high-voltage power supply, 113: Control unit, 114,114b: Sample chamber, 115: Vacuum pump, 116: Image sensor, 117: Sample height adjustment mechanism, 118: Control unit, 201: First cathode, 202: Second cathode, 203: Anode, 204: Permanent magnet, 205: Accelerating electrode, 206: Gas piping, 207: Gas flow control unit.

Claims

1. The sample room and, A sample stage is placed in the aforementioned sample chamber and is equipped with a sample holder on which a sample has been set, Each of the multiple ion sources attached to the sample chamber via an ion source movable mechanism, It has a control unit, The sample stage is tiltable about a tilt axis, and the sample is rotated about a sample rotation axis perpendicular to the tilt axis. The plurality of ion sources are adjusted by the ion source movable mechanism to which the ion sources are attached so that the eccentricity, which is the distance between the ion beam central axis and the sample rotation axis on the sample surface, is different from that of the others. The control unit is an ion milling apparatus that performs milling by irradiating a sample, which is rotated around the sample rotation axis by the sample stage, with unfocused ion beams from the plurality of ion sources.

2. In claim 1, It has a control unit, The control unit has registered the relationship between the ion beam diameter or ion beam current amount on the sample surface of the ion beam emitted by the ion source and the irradiation conditions of the ion beam by the ion source. An ion milling apparatus in which, when the ion beam diameter or ion beam current amount on the sample surface of the plurality of ion sources is set as processing conditions for the milling process, the control unit determines the irradiation conditions of the ion beam to be set in the control unit based on the relationship.

3. In claim 2, An ion milling apparatus whose irradiation conditions for the ion beam include at least a discharge voltage and an acceleration voltage applied to the ion source.

4. In claim 1, Control unit and The system includes an image sensor that captures the processed surface formed on the sample surface by the milling process, The control unit is an ion milling apparatus that determines the progress of the milling process based on the image of the processed surface captured by the image sensor.

5. In claim 4, The control unit adjusts the eccentricity of the plurality of ion sources when it determines that the milling process is insufficient based on the image of the processed surface.

6. In claim 4, The control unit determines the progress of the milling process based on the color of the image of the processed surface.

7. The sample room and, A sample stage is positioned in the aforementioned sample chamber and is equipped with a sample holder on which a sample has been set via a sample height adjustment mechanism. Multiple ion sources attached to the aforementioned sample chamber, It has a control unit, The sample stage is tiltable about a tilt axis, and the sample is rotated about a sample rotation axis perpendicular to the tilt axis. The aforementioned plurality of ion sources are arranged such that their ion beam central axes intersect at a single point on the sample rotation axis. The control unit is an ion milling apparatus that performs milling by irradiating a sample, which is rotated around the sample rotation axis by the sample stage, with an unfocused ion beam from the plurality of ion sources, while the sample surface is adjusted to a height different from the aforementioned point by the sample height adjustment mechanism.

8. In claim 7, The plurality of ion sources include a first to a third ion source, The first ion source is positioned between the second ion source and the third ion source. An ion milling apparatus in which the angle between the ion beam central axis of the first ion source and the ion beam central axis of the second ion source is different from the angle between the ion beam central axis of the first ion source and the ion beam central axis of the third ion source.

9. A processing method for milling a sample using an ion milling apparatus, The ion milling apparatus comprises a sample chamber, a sample stage located within the sample chamber and on which a sample holder containing a sample is mounted, a plurality of ion sources attached to the sample chamber, and a control unit. The sample stage is tiltable about a tilt axis, and the sample is rotated about a sample rotation axis perpendicular to the tilt axis. The plurality of ion sources are adjusted so that their eccentricity, which is the distance between the central axis of the ion beam on the sample surface and the rotation axis of the sample, is different from each other. The control unit performs milling by irradiating the sample, which is rotated around the sample rotation axis by the sample stage, with unfocused ion beams from the plurality of ion sources.

10. In claim 9, The ion milling apparatus includes a control unit, The control unit has registered the relationship between the ion beam diameter or ion beam current amount on the sample surface of the ion beam emitted by the ion source and the irradiation conditions of the ion beam by the ion source. A processing method in which, when the control unit is set as a processing condition for milling the ion beam diameter or ion beam current amount on the sample surface of the plurality of ion sources, the control unit determines the irradiation conditions of the ion beam to be set in the control unit based on the relationship.

11. In claim 10, The processing method includes, as irradiation conditions for the ion beam, at least a discharge voltage and an acceleration voltage applied to the ion source.

12. In claim 9, The ion milling apparatus comprises a control unit and an image sensor for capturing images of the processed surface formed on the sample surface by the milling process. The control unit determines the progress of the milling process based on an image of the processed surface captured by the image sensor.

13. In claim 12, The control unit determines, based on the image of the processed surface, that the milling process is insufficient, and the processing method involves adjusting the eccentricity of the plurality of ion sources.

14. In claim 12, The control unit determines the progress of the milling process based on the color of the image on the processed surface.

Images