Ion milling device

Abstract

The present invention increases the amount of change in the frequency of a quartz oscillator (40) per unit time. An ion milling device (100) comprises: an ion source (20) capable of applying an ion beam; a sample stage (30) on which a sample can be mounted; a first inclination mechanism (31) which is connected to the sample stage (30) in order to adjust the inclination angle of the sample stage (30); a quartz oscillator (40); an oscillation circuit (8) which is electrically connected to the quartz oscillator (40), oscillates the quartz oscillator (40), and receives a frequency outputted from the quartz oscillator (40); a second inclination mechanism (41) which is connected to the quartz oscillator (40) in order to adjust the inclination angle of the quartz oscillator (40); and a control unit (2). The control unit (2) is electrically connected to the ion source (20), the first inclination mechanism (31), the oscillation circuit (8), and the second inclination mechanism (41), and can control the operations thereof.

Description

Technical Field

[0001] The present invention relates to an ion milling apparatus, and more particularly to an ion milling apparatus equipped with a crystal oscillator.

Background Art

[0002] In recent years, ion milling using an ion beam has been used as a method for producing a sample without stress. Such a sample is produced as an observation target for an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and is composed of, for example, metal, semiconductor, glass, or ceramic.

[0003] An ion milling apparatus is an apparatus that irradiates a non-focused ion beam toward a sample and knocks off atoms on the surface of the sample by a sputtering phenomenon. Thereby, the surface of the sample can be polished without stress, and the internal structure of the sample can be exposed. The surface of the polished sample or the internal structure of the sample becomes an observation surface such as an SEM or a TEM.

[0004] For example, Patent Document 1 discloses an ion milling apparatus in which a crystal oscillator that is constantly oscillating is arranged near a sample. Further, Patent Document 1 discloses a method for obtaining the processing amount of a sample from the amount of change in frequency according to the amount of sputtering particles adhering to the crystal oscillator.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When adopting the method using the crystal oscillator as described above, the scattering direction of the sputtering particles changes according to the irradiation angle of the ion beam with respect to the sample. Therefore, in order to increase the amount of change in the frequency of the crystal oscillator per unit time and improve the time resolution with respect to the amount of change in frequency, it is important that the crystal oscillator is positioned at a position where more sputtering particles can adhere. If such a technique can be established, for example, when the processed amount of the sample reaches the target processed amount, the irradiation of the ion beam can be accurately stopped.

[0007] Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0008] Among the embodiments disclosed in the present application, the outline of typical ones will be briefly described as follows.

[0009] The ion milling apparatus in one embodiment includes an ion source capable of irradiating an ion beam, a sample stage on which a sample can be placed, a first tilting mechanism connected to the sample stage and for adjusting the tilting angle of the sample stage, a crystal oscillator, an oscillation circuit electrically connected to the crystal oscillator, for vibrating the crystal oscillator and receiving the frequency output from the crystal oscillator, a second tilting mechanism connected to the crystal oscillator and for adjusting the tilting angle of the crystal oscillator, and a control unit electrically connected to the ion source, the first tilting mechanism, the oscillation circuit, and the second tilting mechanism and capable of controlling their operations.

Advantages of the Invention

[0010] According to one embodiment, the amount of change in the frequency of the crystal oscillator per unit time can be increased.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, members having the same function are denoted by the same reference numerals, and the repeated description thereof is omitted. Further, in the following embodiments, the description of the same or similar parts is not repeated in principle unless particularly necessary.

[0013] Also, the X direction, Y direction, and Z direction described in the present application intersect each other and are orthogonal to each other.

[0014] (Embodiment 1) <Structure of Ion Milling Device> The ion milling device 100 in Embodiment 1 will be described below with reference to FIGS. 1 to 5. The ion milling device 100 is used as a pretreatment device for preparing a sample to be observed with an electron microscope such as SEM or TEM. FIG. 1 is a schematic view of the main part of the ion milling device 100 as viewed from the X direction, and FIG. 2 is a schematic view of the main part of the ion milling device 100 as viewed from the Y direction.

[0015] As shown in FIG. 1, the ion milling device 100 mainly includes a sample chamber 1, a control unit 2, a display unit 3, a vacuum exhaust unit 4, a high voltage unit 5, a gas supply unit 6, a pipe 7, an oscillation circuit 8, an ion source 20, a sample stage 30, a first tilting mechanism 31 for the sample stage, a crystal oscillator 40, and a second tilting mechanism 41 for the crystal oscillator.

[0016] The control unit 2 is electrically connected to the vacuum exhaust unit 4, the ion source 20 (high voltage unit 5), the gas supply unit 6, the oscillation circuit 8, the first tilting mechanism 31, and the second tilting mechanism 41, and can control the operations of these components. The display unit 3 is electrically connected to the control unit 2. Various information related to the operations performed by the ion milling device 100 is displayed on the display unit 3. The user can check various information on the display unit 3 and input various instructions to the control unit 2.

[0017] Inside the sample chamber 1, an ion source 20 capable of irradiating an ion beam, a sample stage 30 on which a sample can be placed, a first tilting mechanism 31, a crystal oscillator 40, and a second tilting mechanism 41 are provided. Note that the sample stage 30 includes a sample table 32 as a part of the members constituting the sample stage 30. The sample table 32 is configured by a sample holder or the like that can place and fix a sample. In this application, placing a sample on the sample stage 30 will be described as being synonymous with placing a sample on the sample table 32.

[0018] By driving the vacuum exhaust unit 4, the inside of the sample chamber 1 is evacuated from atmospheric pressure to a high vacuum (1.0×10 -3It can be adjusted to a pressure of less than Pa. During the irradiation of the ion beam, the inside of the sample chamber 1 is maintained at a high vacuum. Therefore, a stable ion beam can be irradiated onto the sample without being affected by the gas in the atmosphere.

[0019] In the gas supply unit 6, the flow rate of argon (Ar) gas for supplying to the ion source 20 through the pipe 7 is adjusted. The argon gas supplied from the gas supply unit 6 to the ion source 20 is ionized by the high voltage unit 5 and irradiated as a non-focused ion beam from the ion source 20 toward the sample placed on the sample stage 30.

[0020] As shown in FIGS. 1 and 2, the first tilting mechanism 31 is connected to the sample stage 30 and is provided for adjusting the tilting angle of the sample stage 30. Further, a motor 33 is attached to the first tilting mechanism 31. The second tilting mechanism 41 is connected to the crystal oscillator 40 and is provided for adjusting the tilting angle of the crystal oscillator 40. Further, a motor 42 is attached to the second tilting mechanism 41. The distance between the sample stage 30 and the crystal oscillator 40 is maintained at, for example, a distance L1.

[0021] The motor 33 and the motor 42 are electrically connected to the control unit 2, and the rotation speed of each of the motor 33 and the motor 42 can be individually controlled by the control unit 2. That is, by driving the motor 33 and the motor 42 by the control unit 2, the first tilting mechanism 31 and the second tilting mechanism 41 move in the Y-Z plane, and the sample stage 30 and the crystal oscillator 40 tilt in the Y-Z plane.

[0022] Note that the method of moving the first tilting mechanism 31 and the second tilting mechanism 41 is not limited to the control by the rotation speed of each of the motor 33 and the motor 42. For example, tilt sensors may be provided on the first tilting mechanism 31 and the second tilting mechanism 41, and the tilt angle may be determined with reference to them. Further, although the motor 33 and the motor 42 are used here, scales may be provided on the first tilting mechanism 31 and the second tilting mechanism 41, and the first tilting mechanism 31 and the second tilting mechanism 41 may be moved manually by the user with reference to those scales.

[0023] The oscillation circuit 8 is electrically connected to the crystal oscillator 40, vibrates the crystal oscillator 40, and receives the frequency output from the crystal oscillator 40. The frequency received by the oscillation circuit 8 is transmitted to the control unit 2.

[0024] FIG. 3 shows the detailed structure of the ion source 20 adopting the Penning method.

[0025] As shown in FIG. 3, the ion source 20 includes a first cathode electrode 21, a second cathode electrode 22, an anode electrode 23, a permanent magnet 24, and an acceleration electrode 25. The ion source 20 is electrically connected to the control unit 2 via the high voltage unit 5, and various voltages are applied to each electrode from the high voltage unit 5.

[0026] Inside the ion source 20, argon gas is supplied from the gas supply unit 6 through the pipe 7. The first cathode electrode 21 and the second cathode electrode 22 are arranged opposite to each other, and the anode electrode 23 is arranged between the first cathode electrode 21 and the second cathode electrode 22. A discharge voltage Vd is applied from the high voltage unit 5 between the first cathode electrode 21 and the anode electrode 23 and between the second cathode electrode 22 and the anode electrode 23, generating electrons. Due to the permanent magnet 24 arranged inside the ion source 20, a Lorentz force acts on the electrons, causing the electrons to move in a helical motion, thus lengthening the path.

[0027] When the electrons collide with the argon gas, argon ions are generated. An acceleration voltage Va is applied from the high voltage unit 5 between the anode electrode 23 and the acceleration electrode 25, and the generated argon ions are drawn out by the acceleration electrode 25 and emitted as an ion beam outside the ion source 20.

[0028] The arrangement relationship and movement directions of the first tilting mechanism 31 and the second tilting mechanism 41 will be described below with reference to FIGS. 4 and 5. FIGS. 4 and 5 show a state in which a sample 50 is placed on the sample stage 30. The sample 50 is, for example, a metal, semiconductor, glass, ceramic, etc., or a structure composed of a composite of these.

[0029] As shown in FIG. 4, the first tilting mechanism 31 and the second tilting mechanism 41 can rotate and move about an axis perpendicular to the central axis DA (Y direction) of the ion beam in the X direction. Here, the rotation axes of the first tilting mechanism 31 and the second tilting mechanism 41 are coaxial. When the first tilting mechanism 31 rotates and moves, the sample stage 30 tilts. When the second tilting mechanism 41 rotates and moves, the crystal oscillator 40 tilts. In FIG. 4, the tilting angle θ1 of the sample stage 30 with respect to the central axis DA of the ion beam and the tilting angle θ2 of the crystal oscillator 40 with respect to the central axis DA of the ion beam are shown.

[0030] As shown in FIG. 5, during the processing of the sample 50, when the ion beam IB is irradiated from the ion source 20 to the sample 50, sputtering particles SP are generated from the sample 50 due to the sputtering phenomenon. The scattering direction of the sputtering particles SP depends on the tilting angle θ1 of the sample stage 30.

[0031] That is, since the angular distribution of the scattering direction of the sputtering particles SP follows Lambert's cosine law, the sputtering particles SP adhere to the crystal oscillator 40 the most on the perpendicular line DB perpendicular to the surface of the sample 50 (the surface of the sample stage 30). Therefore, when the sample 50 is placed on the sample stage 30, the control unit 2 adjusts the tilting angle θ2 of the crystal oscillator 40 by the second tilting mechanism 41 so that the crystal oscillator 40 is located on the perpendicular line DB perpendicular to the surface of the sample 50.

[0032] Thus, before processing the sample 50, it is desirable to set the tilt angle θ2 in consideration of the tilt angle θ1 set as a predetermined angle. Note that it is most preferable that the sample 50 is disposed at the coordinates where the central axis DA of the ion beam IB intersects the perpendicular line DB.

[0033] However, due to assembly errors or control errors of the ion milling apparatus 100, it may not be possible to accurately position the sample 50 at the above coordinates. In that case, a three-direction mechanism capable of moving in the X, Y, and Z directions may be provided in the ion source 20 or the sample stage 30, and the three-direction mechanism may be adjusted so that the position of the sample 50 becomes the above coordinates.

[0034] After irradiation with the ion beam IB, when a part of the generated sputtering particles SP adheres to the crystal oscillator 40, the mass of the entire crystal oscillator 40 changes by the amount of adhesion Δw. Then, the frequency output from the crystal oscillator 40 to the oscillation circuit 8 changes depending on the adhesion amount Δw of the sputtering particles SP, and when the frequency reaches the target value, the control unit 2 controls the ion source 20 to stop the irradiation with the ion beam IB. That is, the control unit 2 determines that the state where the frequency reaches the target value is the state where the processing of the sample 50 is completed, and automatically stops the irradiation with the ion beam IB.

[0035] In addition, in order to determine the end of the processing of the sample 50 from the target frequency, data on the structure constituting the sample 50 and data on which frequency is to be determined as the target frequency for determining the end of processing when the sample 50 is ion milled at a distance L1 are recorded in the control unit 2 in advance. The control unit 2 can compare the recorded target frequency with the actually acquired frequency and automatically determine whether the processing of the sample 50 can be ended.

[0036] As described above, the sputtering particles SP adhere to the crystal oscillator 40 the most on the perpendicular line DB perpendicular to the surface of the sample 50. Therefore, by adjusting the tilt angle θ2 to be the same as the tilt angle θ1, the deposition amount Δw / t of the sputtering particles SP per unit time can be increased. Therefore, an ion milling apparatus 100 with improved time resolution with respect to the change amount of the frequency can be provided.

[0037] The tilt angle θ2 does not have to be exactly the same as the tilt angle θ1 and may deviate slightly from the tilt angle θ1. Even in that case, as long as the crystal oscillator 40 does not deviate from the perpendicular line DB and is within a range where it is located on the perpendicular line DB, the deposition amount Δw / t per unit time can be sufficiently increased.

[0038] Also, since the crystal oscillator 40 is always controlled by the oscillation circuit 8, during the irradiation of the ion beam IB, the change amount of the frequency is always monitored by the control unit 2. The user can check the change amount of the frequency on the display unit 3.

[0039] During the irradiation of the ion beam IB, the tilt angle θ2 does not have to be always constant and may be changed. The control unit 2 can change the tilt angle θ2 of the crystal oscillator 40 by the second tilt mechanism 41 according to the change in the frequency output from the crystal oscillator 40 to the oscillation circuit 8 during the irradiation of the ion beam IB. For example, during the irradiation of the ion beam IB, the state of the processed surface of the sample 50 may change, the scattering direction of the sputtering particles SP may change, and the deposition amount Δw may be insufficient. In that case, by the user sending an instruction to the control unit 2, the tilt angle θ2 can also be changed so as to increase the deposition amount Δw.

[0040] <Method for processing a sample> Hereinafter, with reference to the flowchart of FIG. 6, a method for processing the sample 50 using the ion milling apparatus 100 in the first embodiment will be described.

[0041] First, in step S1, the processing conditions of the ion milling apparatus 100 are set. The processing conditions include the acceleration voltage of the ion source 20, the discharge voltage of the ion source 20, the supply amount of argon gas, the position of the sample stage 30, the data of the structure constituting the sample 50, and the setting of the target frequency at which processing ends. Next, the inside of the sample chamber 1 is set to a high vacuum, the sample 50 is transported from the outside of the sample chamber 1, and the sample 50 is placed on the sample stage 30.

[0042] In step S2, the control unit 2 moves the first tilting mechanism 31 via the motor 33 and tilts the sample stage 30 until it reaches an arbitrary tilting angle θ1.

[0043] In step S3, the control unit 2 moves the second tilting mechanism 41 via the motor 42 and tilts the crystal oscillator 40 until it reaches a tilting angle θ2. Here, the control unit 2 adjusts the tilting angle θ2 of the crystal oscillator 40 by the second tilting mechanism 41 so that the crystal oscillator 40 is positioned on the perpendicular line DB perpendicular to the surface of the sample 50.

[0044] In step S4, it is confirmed whether the tilting angle θ1 and the tilting angle θ2 are appropriate. For example, it is confirmed whether the tilting angle θ2 is the same as the tilting angle θ1. If correction is necessary (NO), the process returns to step S2 and adjustment is performed again. If correction is not necessary (YES), the next step is step S5, and ion milling processing is started on the sample 50.

[0045] In step S6, an ion beam IB is irradiated from the ion source 20 to the sample 50. Thereby, sputtering particles SP are generated from the sample 50, and a part of the sputtering particles SP adheres to the crystal oscillator 40. Then, the frequency output from the crystal oscillator 40 to the oscillation circuit 8 changes according to the adhesion amount Δw of the sputtering particles SP.

[0046] In step S7, it is confirmed whether the frequency of the target value has been obtained. The control unit 2 determines the frequency received from the oscillation circuit 8, and when the frequency is the same as the frequency of the preset target value, the control unit 2 controls the ion source 20 to stop the irradiation of the ion beam IB. Note that the stop of the irradiation of the ion beam IB may be automatically performed by the control unit 2, or may be performed by the user by referring to the change amount of the frequency displayed on the display unit 3.

[0047] If the frequency of the target value has not been obtained (NO), the process returns to step S6 and the irradiation of the ion beam is continued. If the frequency of the target value has been obtained (YES), the next step is step S8 and the ion milling process is completed. After that, the sample 50 is transported from the sample stage 30 to the outside of the sample chamber 1.

[0048] (Embodiment 2) Hereinafter, the ion milling apparatus 100 in Embodiment 2 will be described with reference to FIGS. 7 and 8. In the following description, the differences from Embodiment 1 will be mainly described, and the description of the points overlapping with Embodiment 1 will be omitted.

[0049] As shown in FIG. 7, in Embodiment 2, not only the second inclination mechanism 41 but also a moving mechanism 43 is connected to the crystal oscillator 40. The moving mechanism 43 is provided to bring the crystal oscillator 40 closer to the sample stage 30 or to move the crystal oscillator 40 away from the sample stage 30. Note that the control unit 2 is electrically connected to the moving mechanism 43 and can control the operation of the moving mechanism 43.

[0050] The distance L2 shown in FIG. 7 is the maximum distance that the moving mechanism 43 can move. In FIG. 7, a state where the moving mechanism 43 has approached the sample stage 30 by the distance ΔL2 is shown, and the distance between the sample stage 30 and the crystal oscillator 40 is shown as the distance L1'.

[0051] In the ion milling apparatus 100, the same sample 50 is not always processed, and the structures constituting the sample 50 vary. For various types of samples 50, since the distribution of the scattering distance or scattering direction of the sputtering particles SP is different, the optimum value of the distance L1 between the sample stage 30 and the crystal oscillator 40 also differs. If the distance L1 is always a constant value, depending on the sample 50, the amount of sputtering particles SP adhered, Δw, may not be sufficiently obtained.

[0052] Therefore, as in the second embodiment, by making the distance L1 variable by the moving mechanism 43, it is possible to obtain a suitable adhesion amount Δw for each of various types of samples 50. For example, even when the scattering distance of the sputtering particles SP is short or when the scattering direction of the sputtering particles SP is divergent, if the distance between the sample stage 30 and the crystal oscillator 40 is shortened like the distance L1', a decrease in the adhesion amount Δw can be prevented.

[0053] Also, even for samples 50 of the same material, the amount of ion milling to be performed may differ. Considering performing ion milling on samples 50 of the same material for the same time, the adhesion amount Δw tends to be larger when the crystal oscillator 40 is closer to the sample stage 30 and tends to be smaller when the crystal oscillator 40 is farther from the sample stage 30.

[0054] For example, when the amount of ion milling may be small, by bringing the crystal oscillator 40 closer to the sample stage 30, it is possible to reach the desired adhesion amount Δw and the target frequency in a shorter time. Therefore, without changing the setting of the processing conditions of the ion milling apparatus 100 for a certain sample 50, the amount of ion milling can be reduced.

[0055] Note that the processing method of the sample 50 in the second embodiment includes step S9 in FIG. 8 in addition to steps S1 to S8 in FIG. 6. In step S9, after checking the inclination angle θ1 and the inclination angle θ2 in step S4, a distance ΔL2 for moving the moving mechanism 43 is set. Thereby, the distance L1 between the sample stage 30 and the crystal oscillator 40 can be adjusted. Thereafter, steps S5 and subsequent steps are performed.

[0056] (Modification example) Hereinafter, a modification example of the second embodiment will be described with reference to FIGS. 9 to 11.

[0057] In the second embodiment, step S9 was added before the irradiation of the ion beam IB to adjust the distance L1 between the sample stage 30 and the crystal oscillator 40. In the modification example, the same point as in the second embodiment is that step S9 is added, but as shown in FIG. 9, step S10 for changing the distance L1 is performed between step S6 and step S7.

[0058] That is, in the modification example, during the irradiation of the ion beam IB, the control unit 2 can change the distance L1 between the crystal oscillator 40 and the sample stage 30 by the moving mechanism 43 according to the change in the frequency output from the crystal oscillator 40 to the oscillation circuit 8.

[0059] FIG. 10 shows a state immediately after the irradiation of the ion beam IB and before the change of the distance L1. FIG. 11 shows a state after a certain time has elapsed from the irradiation of the ion beam IB and after the distance L1 has been changed to the distance L1'.

[0060] As shown in FIG. 10, immediately after the irradiation of the ion beam IB, the sputtering particles SP scatter most onto the perpendicular line DB perpendicular to the surface of the sample 50. However, as shown in FIG. 11, as time passes, the surface of the sample 50 may be processed into a concave shape. In that case, the sputtering particles SP tend to diverge not only in the direction of the perpendicular line DB but also in other directions.

[0061] Then, the deposition amount Δw per unit time gradually becomes constant and then decreases. Therefore, the change amount of the frequency per unit time also gradually becomes constant and then decreases. For example, at the timing when the change amount of the frequency per unit time becomes constant, the crystal oscillator 40 is moved by the moving mechanism 43 by a distance ΔL2 to bring the crystal oscillator 40 closer to the sample 50. Thereby, a large deposition amount Δw can be obtained in a short time, and the target frequency can be obtained in a short time.

[0062] Also, during the irradiation of the ion beam IB, the distance L1 can be changed, and the inclination angle θ2 can be changed in the same manner as in the first embodiment. Thereby, the crystal oscillator 40 can be moved to a more optimal position, and a large deposition amount Δw can be obtained in a short time.

[0063] (Embodiment 3) Hereinafter, the ion milling apparatus 100 in the third embodiment will be described with reference to FIG. 12. In the following description, the differences from the first embodiment will be mainly described, and the description of the points overlapping with the first embodiment will be omitted.

[0064] In the first embodiment, the first inclination mechanism 31 and the second inclination mechanism 41 are provided as different members and are individually controlled.

[0065] As shown in FIG. 12, in the third embodiment, the first inclination mechanism 31 and the second inclination mechanism 41 are integrated. In other words, the sample stage 30 and the crystal oscillator 40 are connected to the same inclination mechanism. Therefore, in order to rotate and move the first inclination mechanism 31 and the second inclination mechanism 41, it is only necessary to provide either one of the motor 33 or the motor 42 in the ion milling apparatus 100.

[0066] Note that, similar to Embodiment 1, the integrated first tilting mechanism 31 and second tilting mechanism 41 can rotate and move about an axis perpendicular to the central axis DA (Y direction) of the ion beam IB (X direction). Further, since the first tilting mechanism 31 and the second tilting mechanism 41 are integrated, these axes of rotation are necessarily coaxial, and the tilting angle θ2 of the crystal oscillator 40 is changed following the change in the tilting angle θ1 of the sample stage 30.

[0067] That is, when the integrated first tilting mechanism 31 and second tilting mechanism 41 are prepared, if they are designed in advance such that the tilting angle θ1 and the tilting angle θ2 are the same, the tilting angle θ2 will always be the same as the tilting angle θ1.

[0068] In Embodiment 3, the tilting angle θ1 and the tilting angle θ2 cannot be controlled individually. However, for example, if the tilting angle θ2 is always the same as the tilting angle θ1, the crystal oscillator 40 can always be positioned on the perpendicular line DB. Further, if only one of the tilting angle θ1 or the tilting angle θ2 is adjusted, there is no need to adjust the other. That is, since one of step S2 or step S3 in FIG. 6 and step S4 can be omitted, the working time of the ion milling process can be shortened.

[0069] Further, the moving mechanism 43 described in Embodiment 2 can also be connected to the crystal oscillator 40 independently of the integrated first tilting mechanism 31 and second tilting mechanism 41. Thereby, also in Embodiment 3, the distance L1 between the sample stage 30 and the crystal oscillator 40 can be made variable, and the same effect as in Embodiment 2 can be obtained.

[0070] Note that the axes of rotation of the first tilting mechanism 31 and the second tilting mechanism 41 are preferably provided at positions where the distance from the sample stage 30 and the distance from the crystal oscillator 40 are equal. That is, the axis of rotation is preferably provided at a position that is half of the distance L1 (distance L1 / 2).

[0071] Although the present invention has been specifically described based on the embodiments for carrying out the invention, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

Explanation of Signs

[0072] 100 Ion milling device 1 Specimen chamber 2 Control unit 3 Display unit 4 Vacuum exhaust unit 5 High voltage unit 6 Gas supply unit 7 Pipe 8 Oscillation circuit 20 Ion source 21 First cathode electrode 22 Second cathode electrode 23 Anode electrode 24 Permanent magnet 25 Accelerating electrode 30 Specimen stage 31 First tilting mechanism for specimen stage 32 Specimen holder 33 Motor of first tilting mechanism 40 Crystal oscillator 41 Second tilting mechanism for crystal oscillator 42 Motor of second tilting mechanism 43 Moving mechanism 50 Specimen DA Central axis of ion beam DB Perpendicular line perpendicular to surface of specimen IB Ion beam SP Sputtering particles

Claims

1. An ion source capable of irradiating an ion beam, A sample stage on which a sample can be placed, A first tilting mechanism connected to the sample stage and for adjusting the tilting angle of the sample stage, A crystal oscillator, An oscillation circuit electrically connected to the crystal oscillator, oscillating the crystal oscillator, and receiving the frequency output from the crystal oscillator, A second tilting mechanism connected to the crystal oscillator and for adjusting the tilting angle of the crystal oscillator, A control unit electrically connected to the ion source, the first tilting mechanism, the oscillation circuit, and the second tilting mechanism, and capable of controlling the operations thereof, An ion milling apparatus comprising the above.

2. In the ion milling apparatus according to Claim 1, The first tilting mechanism and the second tilting mechanism are ion milling apparatuses capable of rotational movement with a direction perpendicular to the central axis of the ion beam as the rotation axis.

3. In the ion milling apparatus according to Claim 2, The rotation axis of the first tilting mechanism and the rotation axis of the second tilting mechanism are coaxial, which is an ion milling apparatus.

4. In the ion milling apparatus according to Claim 1, When the sample is placed on the sample stage, the control unit adjusts the tilting angle of the crystal oscillator by the second tilting mechanism so that the crystal oscillator is located on a perpendicular line perpendicular to the surface of the sample. This is an ion milling apparatus.

5. In the ion milling apparatus according to Claim 4, During the processing of the sample, the ion beam is irradiated from the ion source to the sample, sputtering particles are generated from the sample, a part of the generated sputtering particles adheres to the crystal oscillator, and the frequency output from the crystal oscillator to the oscillation circuit changes according to the amount of the adhered sputtering particles. When the frequency reaches the target value, the control unit controls the ion source to stop the irradiation of the ion beam. This is an ion milling apparatus.

6. In the ion milling apparatus according to Claim 5, The control unit can change the tilting angle of the crystal oscillator by the second tilting mechanism according to the change in the frequency output from the crystal oscillator to the oscillation circuit during the irradiation of the ion beam. This is an ion milling apparatus.

7. In the ion milling apparatus according to Claim 1, The crystal oscillator is connected with a moving mechanism for bringing the crystal oscillator closer to the sample stage or moving the crystal oscillator away from the sample stage. The control unit is an ion milling apparatus that is electrically connected to the moving mechanism and can control the operation of the moving mechanism. **Claim 8** In the ion milling apparatus according to Claim 7, the control unit is an ion milling apparatus that can change the distance between the crystal oscillator and the sample stage by the moving mechanism according to a change in the frequency output from the crystal oscillator to the oscillation circuit during irradiation with the ion beam. **Claim 9** In the ion milling apparatus according to Claim 1, the first tilting mechanism and the second tilting mechanism are integrated, and the ion milling apparatus is configured such that the tilting angle of the crystal oscillator is changed following a change in the tilting angle of the sample stage.

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