Ion milling equipment

Abstract

Provided is an ion milling device which, even when there is a short between an anode and a cathode and sample processing is interrupted, can automatically resume the sample processing. This ion milling device comprises: a sample chamber (111); a sample stage (102) which is disposed inside the sample chamber and on which a sample is placed; an ion source (101) which is provided with a first internal electrode (203) and a second internal electrode (202); a rod-shaped electrode (106) which can be inserted into and removed from the ion source; and a power source unit (108) which is connected to the first internal electrode (203), the second internal electrode (202), and the rod-shaped electrode (106). In a state in which the rod-shaped electrode (106) is inserted into the ion source (101), the power source unit (108) applies a second discharge voltage between the rod-shaped electrode (106) and the first internal electrode (203) and second internal electrode (202), such that the ion source (101) generates therein ions via the collision of gas and electrons generated by discharge between the rod-shaped electrode (106) and the first internal electrode (203) or the second internal electrode (202).

Description

[Technical field]

[0001] The present invention relates to an ion milling apparatus. [Background technology]

[0002] Ion milling equipment is used to irradiate a sample (such as metal, semiconductor, glass, ceramic, etc.) to be observed with an electron microscope with an unfocused ion beam, sputtering atoms from the sample surface without stress, polishing the sample surface and exposing the internal structure of the sample. The sample surface polished by the ion beam and the exposed internal structure of the sample are then used for observation with a scanning electron microscope or transmission electron microscope.

[0003] Patent Document 1 discloses that an ion milling device is provided with a gas injection means for injecting gas toward an ion gun, and material adhering to the inside of the ion gun is moved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 189614 Summary of the Invention [Problem to be solved by the invention]

[0005] In an ion milling device, a high voltage is applied between the anode and cathode inside the ion source, the gas introduced is ionized with the generated electrons, and an accelerating voltage is applied to extract the ions from the ion source and irradiate the sample. At this time, inside the ion source, the cathode is worn away by the sputtering phenomenon caused by the generated plasma, and a deposition film with conductivity derived from the cathode composition is formed on the inner wall surface of the anode. The deposition film grows over the operation time of the device. The grown deposition film peels off into needle-like pieces, causing a short circuit between the anode and cathode, making it impossible to generate ions. For this reason, it was necessary to disassemble the ion source and remove the short circuit. For this reason, with conventional ion milling devices, it was necessary to interrupt sample processing and remove the deposition film every time a short circuit occurred.

[0006] In the cited document 1, the use of a gas injection means makes it possible to remove the deposited film without disassembling the ion source. However, the sample chamber must be opened to the atmosphere once and then evacuated again after the short circuit is restored, which reduces the processing efficiency.

[0007] For process control in semiconductor manufacturing, when an ion milling device is installed in a factory line to polish the surface of a sample for observation by an electron microscope or to expose the internal structure, it is desirable for the ion milling device to process many samples continuously and automatically. Automatic milling of many samples continuously entails continuous ion beam irradiation for a long period of time. For this reason, it is desirable for the ion milling device to be able to automatically remove the short circuit between the anode and cathode and return to processing in a short time, even if a short circuit occurs. [Means for solving the problem]

[0008] An ion milling apparatus according to one embodiment of the present invention includes a sample chamber, a sample stage arranged in the sample chamber and on which a sample is placed, an ion source including a first internal electrode, a second internal electrode, and an acceleration electrode, a rod-shaped electrode that can be inserted into and removed from the ion source, and a power supply unit connected to the first internal electrode, the second internal electrode, the acceleration electrode, and the rod-shaped electrode; With the rod-shaped electrode retracted from the ion source, the power supply unit applies a first discharge voltage between the first internal electrode and the second internal electrode and an acceleration voltage between the first internal electrode and the acceleration electrode, whereby the ion source accelerates ions generated by collision between the gas and electrons generated by discharge between the first internal electrode and the second internal electrode by the acceleration voltage, and emits them as an unfocused ion beam toward the sample; With the rod-shaped electrode inserted in the ion source, the power supply unit applies a second discharge voltage between the rod-shaped electrode and the first internal electrode and between the rod-shaped electrode and the second internal electrode, causing the ion source to generate ions within the ion source by collision between the gas and electrons generated by discharge between the rod-shaped electrode and the first internal electrode or the second internal electrode.

[0009] An ion milling apparatus as another embodiment of the present invention has a sample chamber, a sample stage disposed within the sample chamber on which a sample is placed, an ion source which accelerates ions generated by electrons generated by discharge between an anode and a cathode using an acceleration electrode to emit them as an unfocused ion beam toward the sample, a power supply unit connected to the anode, the cathode, and the acceleration electrode, a rod-shaped member which can be inserted into and removed from the ion source and has a brush at its tip, and a control unit which, when a short circuit between the anode and the cathode is detected during processing of a sample with an ion beam, causes the power supply unit to stop applying the discharge voltage applied between the anode and the cathode and the acceleration voltage applied between the anode and the acceleration electrode, inserts the rod-shaped member into the ion source, and causes the brush to remove the short circuit between the anode and the cathode. Effect of the Invention

[0010] To provide an ion milling device that can automatically return to sample processing even if a short circuit occurs between the anode and cathode and sample processing is interrupted, thereby enabling the automation of continuous sample processing over long periods of time.

[0011] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Brief description of the drawings]

[0012] [Figure 1A] 1 is a schematic diagram showing a main part of an ion milling apparatus according to a first embodiment. [Figure 1B] FIG. 13 is a diagram showing possible positional relationships between a shutter and an ion source. [Figure 1C] FIG. 13 is a diagram showing possible positional relationships between a shutter and an ion source. [Figure 2A] 2 is a schematic diagram showing an ion source and a power supply circuit that applies a control voltage to an internal electrode of the ion source. FIG. [Figure 2B] 2 is a schematic diagram showing an ion source and a power supply circuit that applies a control voltage to an internal electrode of the ion source. FIG. [Diagram 3] FIG. 2 is a schematic diagram showing a state in which a shaft is inserted into an ion source. [Figure 4] 4 is a flowchart showing a series of operations from the start to the end of sample processing by the ion milling apparatus of the first embodiment. [Diagram 5] FIG. 13 is a schematic diagram showing a main part of an ion milling apparatus according to a second embodiment. [Figure 6] 10 is a flowchart showing a series of operations from the start to the end of sample processing by the ion milling apparatus of the second embodiment. [Figure 7A] FIG. 11 is a schematic diagram showing a state in which a brush shaft is inserted into an ion source in the ion milling apparatus of Example 3. [Figure 7B] This is the source of shaft rotation as viewed from the Y direction. [Figure 8] 11 is a flowchart showing a series of operations from the start to the end of sample processing by the ion milling apparatus of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. EXAMPLES

[0014] Fig. 1A is a schematic diagram showing a side view of a main part of an ion milling apparatus 100 of Example 1. In Fig. 1A, the vertical direction is indicated as the Z direction. The ion milling apparatus 100 has, as its main components, an ion source 101, a sample stage 102, a sample stage drive source 103, a shutter 104, a shutter drive source 105, a shaft (rod-shaped electrode) 106 that functions as an external electrode and can be inserted into and removed from the ion source 101, a shaft drive source 107, a power supply unit 108, a control unit 109, a display unit 110, and a sample chamber 111.

[0015] The ion milling apparatus 100 is used as a pretreatment apparatus for observing the surface or cross section of a sample using a scanning electron microscope or a transmission electron microscope. Ion sources for such pretreatment apparatuses often adopt the Penning method, which is effective for miniaturizing the structure. In this embodiment, the ion source 101 also adopts the Penning method, and an unfocused ion beam is irradiated from the ion source 101 toward a sample placed on a sample stage 102. The output of the ion beam is mainly controlled by a control voltage (acceleration voltage, discharge voltage) applied by a power supply unit 108 to an internal electrode of the ion source 101 and a flow rate of argon gas supplied to the ion source 101.

[0016] The sample stage 102 on which the sample is placed is attached to the sample chamber 111 via a sample stage drive source 103 that positions the sample stage 102. The sample stage drive source 103 rotates the sample stage 102 about a rotation axis R0. The sample stage drive source 103 is attached to the sample chamber 111 so as to adjust the position of the sample stage 102 in each of the X, Y, and Z directions, and also adjust the orientation of the sample stage 102 relative to the ion beam central axis B0 in each of the angular directions of the XZ plane (rotation direction about the T1 axis) and the YZ plane (rotation direction about the T2 axis).

[0017] A shutter 104 is provided in front of the ion source 101 to block the irradiation of the ion beam to a sample. Here, the direction in which the ion beam is emitted is called the front of the ion source, and corresponds to the Y direction in the example of FIG. 1A. The shutter 104 is driven by a shutter drive source 105. Assuming that the shutter 104 is configured to be movable in the Z direction, FIGS. 1B to 1C show possible positional relationships between the shutter 104 and the ion source 101. FIG. 1B shows a state in which the shaft 106 is retracted from the ion source 101 and the shutter 104 is blocking the ion beam emitted from the ion source 101. FIG. 1C shows a state in which the shutter 104 is retracted from the front of the ion source 101, enabling milling of the sample by the ion beam.

[0018] In this example, a shaft driving source 107 is provided for the shutter 104, and the shutter driving source 105 is also used as a driving source for moving the position of the shaft 106 in the Z direction in conjunction with the shutter 104, so that the shaft 106 is located in the same YZ plane as the central axis B0 of the ion beam regardless of the driving status of the shutter driving source 105 and the shaft driving source 107, simplifying the mechanism. Note that the above is an example, and the mechanism is not limited to the one shown in Figures 1A to 1C. For example, the retraction direction of the shutter 104 does not have to be the Z direction, and a dedicated driving source for driving the shaft 106 independently of the shutter 104 may be provided.

[0019] Sample processing using the ion milling apparatus of this embodiment is performed as follows. The shutter 104 blocks irradiation of the sample with the unstable ion beam until the current value of the ion beam from the ion source 101 stabilizes within a preset range. At this time, the shutter 104 is in the position shown in Fig. 1B. After the ion beam current value stabilizes, the shutter 104 is retracted from in front of the ion source 101 by the shutter drive source 105 (Fig. 1C), and irradiation of the ion beam to the sample on the sample stage 102 begins.

[0020] If a short circuit occurs inside the ion source 101 during sample processing, the shutter drive source 105 moves the position of the shaft 106 so that the ion source 101 and the shaft 106 are arranged coaxially. Once the ion source 101 and the shaft 106 are arranged coaxially, the shaft drive source 107 moves the shaft 106 in the Y direction and inserts it into the ion source 101. The state of the shutter 104 and the shaft 106 at this time is the state shown in FIG. 1A. Although details will be described later, in order to remove the short circuit, the power supply unit 108 applies a high voltage between the shaft 106 inserted into the ion source 101 and the internal electrode of the ion source 101.

[0021] The above control is performed by a control unit 109, and the status of the ion source 101, such as the occurrence of a short circuit and recovery from the short circuit, can be confirmed in real time on a display unit 110.

[0022] 2A is a schematic diagram showing an ion source 101 employing the Penning method and a power supply circuit that applies a control voltage to an internal electrode of the ion source 101. The power supply circuit is a part of a power supply unit .

[0023] The ion source 101 has a first cathode 201, a second cathode (second internal electrode) 202, an anode (first internal electrode) 203, a permanent magnet 204, an acceleration electrode 205, and a gas pipe 206. The gas pipe 206 is provided with a mass flow controller 207 that controls the flow rate of argon gas supplied to the ion source 101.

[0024] Inside the ion source 101, a first cathode 201 and a second cathode 202 are arranged via a permanent magnet 204 so as to have the same potential when a voltage is applied. An anode 203 is arranged between the first cathode 201 and the second cathode 202. Electrons are generated by applying a discharge voltage Vd (first discharge voltage) from a power supply unit 108 between the cathodes 201, 202 and the anode 203. The permanent magnet 204 causes the electrons to remain inside the ion source 101 while performing a spiral motion, and they collide with argon gas injected from a gas pipe 206 to generate argon ions. An acceleration voltage Va is applied between the anode 203 and an acceleration electrode 205 from the power supply unit 108, and the generated argon ions are attracted to the acceleration electrode 205 and emitted as an ion beam. The accelerating electrode 205 is set to a reference potential (GND), and potentials for applying control voltages to the cathodes 201, 202 and the anode 203 are supplied from a power supply unit 108. Here, protective resistors R1 and R2 are provided to prevent abrupt fluctuations in the potentials applied to the cathode and anode from adversely affecting the operation of the ion source 101. Instead of the protective resistors, a protective circuit may be provided that cuts off the application of voltage when an abnormality occurs.

[0025] The power supply circuit is provided with an ammeter 208 and a voltmeter 209 between the anode 203 and the first and second cathodes 201 and 202. The ammeter 208 measures the discharge current that flows between the cathode and the anode due to discharge, and the voltmeter 209 measures the discharge voltage that is actually applied between the cathode and the anode during discharge. The discharge current value measured by the ammeter 208 and the discharge voltage value measured by the voltmeter 209 are also output to the control unit 109. The control unit 109 uses the discharge current value and discharge voltage value to monitor the output state of the ion beam, and may display them on the display unit 110.

[0026] As discharges to generate argon ions are repeated, the second cathode 202 is worn down by being sputtered by argon ions. Sputtered particles from the cathode generated by wear are deposited on the inner wall surface of the anode, forming a deposition film 210, which eventually peels off into needle-like shapes, short-circuiting the anode and cathode. Figure 2B shows the ion source 101 with the anode and cathode short-circuited. This short-circuit eliminates the potential difference between the anode and cathode, stopping the discharge and interrupting sample processing.

[0027] FIG. 3 is a schematic diagram showing a state in which the shaft 106 is inserted into the ion source 101 in order to remove the short-circuited portion after the short-circuit occurs between the anode and the cathode shown in FIG. 2B. The control unit 109 detects the occurrence of the short-circuit between the anode and the cathode, for example, when the discharge voltage value measured by the voltmeter 209 drops abnormally. Upon detection of the occurrence of the short-circuit, the control unit 109 stops the application of the control voltage to the ion source 101, and moves the shutter 104 by the shutter drive source 105 to place the shaft 106 coaxially with the opening 211 of the acceleration electrode 205. The reason for placing the shaft 106 coaxially is to prevent the shaft 106 from contacting the internal electrode of the ion source 101 due to a control error or the like. Thereafter, the shaft 106 is inserted into the inside of the ion source 101 by the shaft drive source 107. The power supply unit 108 has a power supply circuit that applies a voltage Ve between the shaft 106 and the acceleration electrode 205. Considering the possibility that the voltage applied to the shaft 106 may suddenly change, a protective resistor R3 is provided. Instead of protective resistor R3, a protective circuit may be provided that cuts off the application of voltage when an abnormality occurs.

[0028] After the shaft 106 is inserted into the ion source 101, the power supply unit 108 applies a high voltage (second discharge voltage) between the shaft 106 and the short-circuited cathodes 201, 202 and anode 203, thereby ionizing the argon gas introduced into the ion source 101. Here, the voltage Ve is set to a voltage value of negative polarity with respect to the reference potential, and the discharge voltage Vd and the acceleration voltage Va are set to 0 V, so that a high voltage (second discharge voltage) is applied between the short-circuited cathodes 201, 202 and anode 203, and a discharge occurs. At this time, the shaft 106 functions as an anode, and the cathodes 201, 202 and anode 203 function as cathodes. In the description of the embodiment, the internal electrodes are referred to as the cathodes 201, 202 and anode 203 based on their functions when emitting an ion beam, for the sake of simplicity. The second discharge voltage may be the sum of the negative voltage Ve and the positive voltage Va to generate a discharge.

[0029] The argon ions remove the deposition film 210 by a sputtering phenomenon, and the short circuit between the anode and the cathode is restored. The restoration of the short circuit can be determined by the voltage applied to the voltmeter 209 appearing when the power supply unit 108 applies a predetermined voltage between the anode and the cathode. When the restoration of the short circuit is detected, the control unit 109 retracts the shaft 106 from the ion source 101.

[0030] 4 shows a series of operations from the start to the end of sample processing by the ion milling apparatus 100 of the first embodiment. The processes from short circuit detection during sample processing to the restart of processing are automatically performed by the control unit 109. The operations at each step will be described below.

[0031] S301: Set sample processing conditions for the ion milling apparatus 100 and start sample processing. The sample processing conditions include the acceleration voltage of the ion source 101, the discharge voltage, the amount of argon gas supplied, the position of the sample stage, the sample processing time, and the like.

[0032] S302: During sample processing, the control unit 109 monitors the discharge current value by the ammeter 208 and the discharge voltage value by the voltmeter 209. When the control unit 109 detects a short circuit between the anode and the cathode from the discharge voltage value measured by the voltmeter 209, it stops the application of the discharge voltage Vd and the acceleration voltage Va from the power supply unit 108 and interrupts the sample processing. At this time, the control unit 109 continues the supply of argon gas to the ion source 101.

[0033] S303: The control unit 109 drives the shutter driving source 105 to move the shaft 106 forward of the ion source 101. At this time, the shaft 106 and the ion source 101 are arranged coaxially.

[0034] S304: The control unit 109 drives the shaft driving source 107 to insert the shaft 106 into the ion source 101.

[0035] S305: A voltage Ve is applied between the short-circuited anode 203 and cathodes 201 and 202 and the shaft 106, thereby discharging between the shaft and the anode and cathode. As a result, the argon gas introduced into the ion source 101 is ionized.

[0036] S306: The short circuit between the anode and cathode is removed by the sputtering phenomenon caused by the generated argon ions.

[0037] S307: After applying voltage Ve to shaft 106 for a certain period of time, a predetermined voltage is applied between anode 203 and cathodes 201, 202 to confirm that the short circuit between the anode and cathode has been removed. Whether the short circuit has been removed can be determined by whether a potential difference corresponding to the applied voltage is measured between the anode and cathode by voltmeter 209. If the short circuit has not been removed, step S306 is executed.

[0038] S308: After the short circuit between the anode and cathode is restored, the control unit 109 stops the application of voltage from the power supply unit 108 to the shaft 106, and drives the shaft driving source 107 to move the shaft 106 away from the ion source 101.

[0039] S309: The control unit 109 drives the shutter driving source 105 to move the shaft 106 away from the front of the ion source 101.

[0040] S310: The interrupted sample processing is resumed according to the sample processing conditions set in step S301.

[0041] S311: If a short circuit between the anode and cathode occurs again during sample processing, the process returns to step S302 to perform an operation to remove the short circuit between the anode and cathode.

[0042] S312: When the sample processing time set in step S301 has elapsed, the sample processing is terminated. EXAMPLES

[0043] 5 is a schematic diagram showing a main part of an ion milling apparatus 100B of the second embodiment from the side. In the ion milling apparatus 100B, a shaft 106 is provided on the sample stage 102 instead of a shutter 104. Components having the same functions as those in the first embodiment are given the same reference numerals, and duplicated explanations will be omitted. A shaft drive source 107 that moves the shaft 106 in the Y direction is provided on the sample stage 102. This makes it possible to share the drive mechanism of the sample stage drive source 103 that drives the sample stage 102 when mounting the shaft drive source 107, simplifying the mechanism.

[0044] The difference from the first embodiment is the process of inserting the shaft 106 when a short circuit occurs inside the ion source 101. In the second embodiment, the shaft 106 is provided on the sample stage 102, and therefore the position and attitude of the sample stage 102 change in order to insert the shaft 106 into the ion source 101. For this reason, the position information and attitude (tilt) information of the sample stage at the time of the short circuit occurrence are stored, and then the shaft 106 is inserted into the ion source 101, and after the short circuit is removed, the position and attitude of the sample stage 102 are restored to the state before the short circuit removal operation based on the stored position information and attitude information of the sample stage.

[0045] 6 shows a series of operations from the start to the end of sample processing by the ion milling apparatus 100B of the embodiment 2. The same steps as those in the flowchart of the embodiment 1 (FIG. 4) are given the same reference numerals, and duplicated explanations will be omitted.

[0046] After the processing is interrupted due to the occurrence of a short circuit between the anode and cathode (S302), the control unit 109 drives the sample stage driving source 103 so that the shaft 106 and the ion source 101 are arranged coaxially. This operation changes the position and attitude of the sample stage 102 from the state before the processing was interrupted. Therefore, the control unit 109 records the state information of the sample stage before the driving of the sample stage driving source 103 (S303'). The state information is information for restoring the sample stage 102 to the state before the processing was interrupted after the short circuit is restored, and includes the position coordinates (x, y, z) of the sample stage 102 and, if necessary, attitude information of the sample stage 102 (tilt θ1 around the T1 axis and tilt θ2 around the T2 axis).

[0047] After driving the sample stage 102, the shaft 106 is inserted into the ion source 101 by the shaft driving source 107 in the same manner as in the first embodiment, and the short-circuited portion between the anode and the cathode is removed. After the short circuit is removed, the shaft 106 is retracted from the ion source 101 (S308), and the sample stage 102 is returned to the state it was in when the processing was interrupted (S309') based on the state information recorded in step S303'. Specifically, the control unit 109 drives the sample stage driving source 103 to move the sample stage 102 to the recorded position coordinates (x, y, z) and tilt the sample stage 102 according to the recorded attitude information. EXAMPLES

[0048] 7A is a schematic diagram showing the ion source 101 of the ion milling apparatus of Example 3 and a power supply circuit that applies a control voltage to the internal electrode of the ion source 101. Example 3 differs from Examples 1 and 2 in the method of removing a short-circuited portion between the anode and cathode.

[0049] A brush 401 is provided at the tip of the shaft (rod-shaped member) 106, and the shaft 106 is attached to a shaft rotation source 402 via a shaft drive source 107. The shaft 106 in the third embodiment does not function as an external electrode, unlike the shaft 106 in the first embodiment, and functions as a support member for the brush 401. FIG. 7B shows the shaft rotation source 402 as seen from the Y direction. The shaft rotation source 402 rotates around a rotation center CC, and the shaft 106 also rotates with the rotation of the shaft rotation source 402. The shaft rotation source 402 is configured to be able to move the holding positions of the shaft 106 and the shaft drive source 107 from the rotation center CC toward the outer periphery of the shaft rotation source 402. The shaft rotation source 402 decenters the holding positions from the rotation center CC by Δr toward the outer periphery. At this time, as shown in FIG. 7A, the brush 401 is in contact with the inner wall surfaces of the second cathode 202 and the anode 203. In this state, the shaft rotation source 402 rotates the shaft 106 about the center of rotation CC, causing the brush 401 to rotate along the inner wall surfaces of the second cathode 202 and the anode 203, thereby removing the deposited film of sputtered particles.

[0050] Here, the brush 401 is made of a material with low rigidity such as resin or rubber so as not to damage the second cathode 202 or the anode 203 that it comes into contact with, and has a shape (L-shaped) with a part that spreads outward. By making it L-shaped, the outermost circumference of the brush 401 that can be reached when the shaft 106 is rotated can be made outside the area in which the shaft 106 rotates. This allows the brush 401 to come into contact with the inner wall surface of the anode 203 without the shaft 106 coming into contact with the acceleration electrode 205. Although an L-shaped brush is shown in FIG. 7A, the shape is not limited to an L-shape as long as the brush 401 can come into contact with the inner wall surface of the anode 203 without the shaft 106 coming into contact with the acceleration electrode 205. In addition, in the example of FIG. 7A, an example in which the shaft rotation source 402 is provided on the shutter 104 as in the first embodiment is shown, but the shaft rotation source 402 may be provided on the sample stage 102 as in the second embodiment.

[0051] The flow chart shown in Fig. 8 shows a series of operations from the start to the end of sample processing by the ion milling apparatus of the embodiment 3. The same steps as those in the flow chart of the embodiment 1 (Fig. 4) or the flow chart of the embodiment 2 (Fig. 6) are given the same reference numerals, and duplicated explanations will be omitted.

[0052] When the occurrence of a short circuit between the anode and the cathode is detected, the processing is interrupted (S302). In the third embodiment, the control unit 109 may stop the supply of argon gas to the ion source 101. Thereafter, the control unit 109 drives the shutter drive source 105 to move the shaft 106 forward of the ion source 101 (S303). At this time, the shaft 106 is positioned at the rotation center CC of the shaft rotation source 402, and the rotation center CC of the shaft rotation source 402 is arranged on the central axis of the ion source 101. As a result, the shaft 106 and the ion source 101 are arranged coaxially.

[0053] In this state, the control unit 109 drives the shaft driving source 107 to insert the shaft 106 into the ion source 101 until the brush 401 contacts the second cathode 202, and then eccentricates the holding position of the shaft 106 of the shaft rotation source 402 by (Δr) until the brush 401 contacts the anode 203 (S304'). The central axis of the eccentric shaft 106 is represented as the central axis CS in Figs. 7A and 7B. Thereafter, the control unit 109 rotates the shaft 106 by the shaft rotation source 402 about the rotation center CC, so that the brush 401 rotates so as to follow the inner wall surfaces of the second cathode 202 and the anode 203, and removes the deposition film of the sputtered particles (S306'). After rotating the brush 401 for a preset fixed time, it is confirmed that the short-circuit point between the anode and the cathode has been removed (S307). The shaft is withdrawn from the ion source. After the short circuit between the anode and the cathode is restored, the control unit 109 drives the shaft driving source 107 to retract the shaft 106 from the ion source 101 (S308').

[0054] The invention made by the present inventor has been specifically described above based on the embodiment, but the present invention is not limited to the described embodiment and can be modified in various ways without departing from the gist of the invention. For example, the shaft used as the external electrode in Example 1 may have a structure including an insulator so that a voltage is applied only to the tip of the shaft inserted into the ion source 101 in order to efficiently cause the sputtering phenomenon by argon ions only at the short-circuited portion. [Explanation of symbols]

[0055] 100, 100B: ion milling apparatus, 101: ion source, 102: sample stage, 103: sample stage drive source, 104: shutter, 105: shutter drive source, 106: shaft, 107: shaft drive source, 108: power supply unit, 109: control unit, 110: display unit, 111: sample chamber, 201: first cathode, 202: second cathode, 203: anode, 204: permanent magnet, 205: acceleration electrode, 206: gas piping, 207: mass flow controller, 208: ammeter, 209: voltmeter, 210: deposited film, 211: opening, 401: brush, 402: shaft rotation source.

Claims

1. A sample chamber; a sample stage disposed in the sample chamber and on which a sample is placed; an ion source including a first inner electrode, a second inner electrode, and an acceleration electrode; A rod-shaped electrode that can be inserted into and removed from the ion source; a power supply unit connected to the first internal electrode, the second internal electrode, the acceleration electrode, and the rod-shaped electrode; With the rod-shaped electrode retracted from the ion source, the power supply unit applies a first discharge voltage between the first internal electrode and the second internal electrode and an acceleration voltage between the first internal electrode and the acceleration electrode, whereby the ion source accelerates ions generated by collision between gas and electrons generated by discharge between the first internal electrode and the second internal electrode by the acceleration voltage, and emits the ions as an unfocused ion beam toward the sample; With the rod-shaped electrode inserted into the ion source, the power supply unit applies a second discharge voltage between the rod-shaped electrode and the first internal electrode and between the rod-shaped electrode and the second internal electrode, thereby causing the ion source to generate ions inside the ion source by collision between gas and electrons generated by discharge between the rod-shaped electrode and the first internal electrode or the second internal electrode.

2. In claim 1, an ion milling apparatus having a control unit that, when a short circuit between the first internal electrode and the second internal electrode is detected during processing of the sample with the ion beam, stops application of the first discharge voltage and the acceleration voltage to the power supply unit, inserts the rod-shaped electrode into the ion source, and then causes the power supply unit to apply the second discharge voltage.

3. In claim 2, The control unit continues to supply the gas to the ion source even after the power supply unit stops applying the first discharge voltage and the acceleration voltage.

4. In claim 3, When the control unit detects removal of the short-circuited portion between the first internal electrode and the second internal electrode, it causes the power supply unit to stop applying the second discharge voltage, retracts the rod-shaped electrode from the ion source, and then causes the power supply unit to resume applying the first discharge voltage and the acceleration voltage.

5. In claim 3, the power supply unit includes a voltmeter that measures a potential difference between the first internal electrode and the second internal electrode; The control unit detects a short circuit or recovery from the short circuit between the first internal electrode and the second internal electrode based on the potential difference measured by the voltmeter.

6. In claim 4, a first drive source that moves the rod-shaped electrode to a position in front of an opening through which the ion source emits the ion beam, and a second drive source that inserts the rod-shaped electrode that has been moved to the position in front of the opening into the ion source, The control unit is an ion milling apparatus that inserts and removes the rod-shaped electrode using the first driving source and the second driving source.

7. In claim 6, a shutter that blocks the irradiation of the ion beam onto the sample; a shutter drive source that drives the shutter, The first driving source is also used as the shutter driving source in the ion milling apparatus.

8. In claim 6, a sample stage drive source for positioning the sample stage; The first driving source is also used as the sample stage driving source in the ion milling apparatus.

9. In claim 8, The control unit of the ion milling apparatus stores state information of the sample stage before starting the operation of inserting the rod-shaped electrode into the ion source, and after retracting the rod-shaped electrode from the ion source, restores the sample stage to the state before starting the operation of inserting the rod-shaped electrode into the ion source based on the state information.

10. In claim 9, The state information of the ion milling apparatus includes position coordinates and attitude information of the sample stage.

11. A sample chamber; a sample stage disposed in the sample chamber and on which a sample is placed; an ion source that accelerates ions generated by electrons generated by discharge between an anode and a cathode using an acceleration electrode, and emits the ions as an unfocused ion beam toward the sample; a power supply unit connected to the anode, the cathode, and the accelerating electrode; A rod-shaped member that can be inserted into and removed from the ion source and has a brush at its tip; and a control unit which, when a short circuit between the anode and the cathode is detected during processing of the sample with the ion beam, causes the power supply unit to stop applying a discharge voltage between the anode and the cathode and an acceleration voltage between the anode and the acceleration electrode, inserts the rod-shaped member into the ion source, and removes the short circuit between the anode and the cathode using the brush.

12. In claim 11, The control unit of the ion milling apparatus, when it detects that the short circuit between the anode and the cathode has been removed, retracts the rod-shaped member from the ion source and then causes the power supply unit to resume applying the discharge voltage and the acceleration voltage.

13. In claim 12, a first drive source that moves the rod-shaped member to the front of an opening from which the ion source emits the ion beam, a second drive source that inserts the rod-shaped member that has been moved to the front of the opening into the ion source, and a rotation source that holds the rod-shaped member and rotates the rod-shaped member about a rotation center, An ion milling apparatus in which the control unit holds the rod-shaped member at the center of rotation of the rotation source and inserts the rod-shaped member into the ion source until it contacts the cathode using the first driving source and the second driving source.

14. In claim 13, the center of rotation of the rod-shaped member is disposed on a central axis of the ion source, The control unit, after the rod-shaped member is inserted into the ion source, shifts the holding position of the rod-shaped member by the rotation source until the brush contacts the cathode, and rotates the rod-shaped member around the center of rotation as an axis using the rotation source.

15. In claim 14, The brush has a shape including a portion that extends outward beyond the rod-shaped member.

Images