Charged particle beam device and sample piece transfer method

Abstract

Provided is a charged particle beam device with which work time can be reduced. A charged particle beam device 100 comprises: a charged particle beam column 1 that radiates an electron beam; a focused ion beam column 2 that radiates a focused ion beam; a first sample stage 5 that can be tilted; a second sample stage 6 that is disposed on the first sample stage 5 and can be tilted independently of the first sample stage 5; an EBSD detector 3; and a sample transfer unit 13. The second sample stage 6 has bulk sample holders 65, 66 on which bulk samples 7, 9 are placed, and a sample piece holder 67 on which sample pieces 7a, 9a extracted from the bulk sample 9 are placed, and a sample placement surface 67S of the sample piece holder 67 has an inclination angle that is set with respect to a bulk sample placement surface 66S of the bulk sample holder 66.

Description

Charged particle beam device and sample piece transfer method

[0001] The present invention relates to a charged particle beam device such as an FIB (focused ion beam)-SEM (scanning electron microscope) and a sample piece transfer method.

[0002] One of the techniques for analyzing the structure of a sample is the electron backscattering diffraction (EBSD) method.

[0003] EBSD observation of an FIB-processed surface is possible using an FIB-SEM (Patent Document 1). Also, a known sample preparation method for detailed observation of a desired observation area of ​​a sample using a TEM (transmission electron microscope) involves removing a micro-sample prepared by thinning using an FIB, transferring it to a sample stage, and then performing additional processing on the micro-sample (Patent Document 2).

[0004] JP 2011-159483 A JP 2004-354371 A

[0005] However, when a region observed by EBSD is to be observed in detail by a TEM or the like, a sample piece of the region observed by EBSD must be prepared by FIB processing, and then the sample piece must be removed from the sample chamber to be positioned in a position suitable for thinning. Furthermore, the removed sample piece must be placed on a sample piece holder, and then brought back into the sample chamber for thinning, which requires time for the work.

[0006] An object of the present invention is to provide a charged particle beam apparatus and a sample piece transfer method that can shorten the above-mentioned operation time.

[0007] In order to achieve the above object, the present invention is configured as follows.

[0008] The charged particle beam device comprises a charged particle beam column that irradiates an electron beam, a focused ion beam column that irradiates a focused ion beam, a tiltable first sample stage, a second sample stage that is arranged on the first sample stage and can be tilted independently of the first sample stage, an EBSD detector, and a sample transfer unit, wherein the second sample stage has a bulk sample holder that mounts a bulk sample, and a sample piece holder that mounts a sample piece extracted from the bulk sample, and the sample mounting surface of the sample piece holder is inclined at an angle relative to the bulk sample mounting surface of the bulk sample holder.

[0009] In addition, a sample piece transfer method includes the steps of exposing an observation surface of a sample on a bulk sample holder by using a focused ion beam, irradiating the observation surface with an electron beam to observe it, irradiating the sample with the focused ion beam to cut out a sample piece from the sample, and transferring the sample piece to a sample mounting surface of the sample piece holder that is inclined at an angle to the bulk sample mounting surface of the bulk sample holder.

[0010] According to the present invention, it is possible to provide a charged particle beam device and a sample piece transfer method that can shorten the operation time.

[0011] FIG. 1 is an overall configuration diagram of a charged particle beam instrument according to an embodiment of the present invention; FIG. 2 is a diagram showing the operation of the sample stage and the positional relationship with each lens column; FIG. 3 is a schematic perspective view of a sample holder; FIG. 4 is a schematic perspective view of an EBSD sample stage; FIG. 5 is a schematic side view of the EBSD sample stage; FIG. 6 is a cross-sectional view illustrating the inclination angle of the sample piece mounting surface in the sample piece holder; FIG. 7 is a flowchart illustrating the operation of observing the flat surface side of a sample, cutting out a sample piece, and transferring it; FIG. 8 is an explanatory diagram of the operation of exposing the flat surface side of the sample as the observation surface; FIG. 9 is an explanatory diagram of the operation of exposing the flat surface side of the sample as the observation surface; FIG. 10 is an explanatory diagram of the operation of detaching a sample piece; FIG. 11 is an explanatory diagram of the operation of detaching a sample piece; FIG. 12 is an explanatory diagram of the operation of transferring a sample piece; FIG. 13 is an explanatory diagram of the operation of thinning a sample piece to a thickness that can be observed; FIG. 14 is an explanatory diagram of the operation of exposing the side surface side of the sample as the observation surface; FIG. 15 is an explanatory diagram of the operation of exposing the side surface side of the sample as the observation surface; FIG. 16 is an explanatory diagram of the operation of detaching a sample piece; FIG. 17 is an explanatory diagram of the operation of detaching a sample piece; FIG. 18 is an explanatory diagram of the operation of transferring a sample piece; FIG.

[0012] Hereinafter, an embodiment of a charged particle beam apparatus according to the present invention will be described.

[0013] 1 shows the overall configuration of a charged particle beam system 100 in Example 1. The composite charged particle beam system 100 includes an FIB column (focused ion beam column (second charged particle beam column)) 2 that irradiates a focused ion beam (FIB) as a first charged particle beam, and an EB column (first charged particle beam column) 1 that irradiates an electron beam (EB) as a second charged particle beam. The charged particle beam column 1 is arranged so that the irradiation axis of the electron beam irradiated from the charged particle beam column 1 (irradiation axis of electron beam 1b) is vertical.

[0014] The charged particle beam device 100 further includes a secondary electron detector 4 that detects secondary electrons generated from the bulk sample 7 by irradiation with EB 1b and FIB 2b. It may also include a backscattered electron detector that detects backscattered electrons generated from a thin sample 7a (described later) by irradiation with EB. The charged particle beam device 100 further includes a port for mounting an EBSD detector 3.

[0015] The charged particle beam device 100 further includes a sample holder 6 (second sample stage) that holds and fixes the thin sample 7a extracted from the bulk sample 7, and a sample stage 5 (first sample stage) on which the sample holder 6 is placed. The sample stage 5 is movable in three axes (X, Y, and Z) (not shown). Furthermore, the sample stage 5 can also be tilted and rotated, as will be described later.

[0016] The charged particle beam device 100 further includes a sample stage control unit 15. The sample stage control unit 15 controls a drive mechanism (not shown) to move the sample stage 5 in the three X, Y, and Z axis directions. Furthermore, the sample stage control unit 15 controls a tilt drive unit 8 to tilt the sample stage 5, and controls a rotation drive unit 10 to rotate the sample stage 5.

[0017] The charged particle beam device 100 further includes a sample holder control unit 60. The sample holder control unit 60 sets the orientation of a thin sample 7a (described later) in a desired direction by driving the sample holder 6 arranged on the sample stage 5. The configuration and operation of the sample holder 6 will be described in detail later.

[0018] The charged particle beam device 100 further includes an FIB control unit 12, an EB control unit 11, an image formation unit 14, and a display unit 18. The EB control unit 11 controls EB irradiation from the EB column 1. The FIB control unit 12 controls FIB irradiation from the FIB column 2. The image formation unit 14 forms an SEM image from a signal for scanning the EB and a secondary electron signal detected by the secondary electron detector 4. The image formation unit 14 also forms an EBSD image from a signal for scanning the EB and an EBSD signal detected by the EBSD detector 3. The display unit 18 can display observation images such as SEM images, various control conditions of the device, and the like. The image formation unit 14 also forms a SIM image from a signal for scanning the FIB and a secondary electron signal detected by the secondary electron detector 4. The display unit 18 can display the SIM image.

[0019] The charged particle beam device 100 further includes an input unit 16 and a control unit 17. An operator inputs conditions related to device control into the input unit 16. The input unit 16 transmits the input information to the control unit 17. The control unit 17 transmits control signals to the FIB control unit 12, EB control unit 11, image formation unit 14, sample stage control unit 15, display unit 18, and sample holder control unit 60, thereby controlling the entire device.

[0020] Regarding the control of the charged particle beam device 100, for example, an operator sets an irradiation area of ​​the FIB based on an observation image such as an SEM image or SIM image displayed on the display unit 18. The operator inputs a processing frame for setting the irradiation area on the observation image displayed on the display unit 18 using the input unit 16. Furthermore, when the operator inputs an instruction to start processing into the input unit 16, the control unit 17 transmits a signal indicating the irradiation area and processing start to the FIB control unit 12, and the FIB control unit 12 irradiates the FIB onto the specified irradiation area of ​​the bulk sample 7. This allows the FIB to be irradiated onto the irradiation area input by the operator.

[0021] 2 shows the main parts of the charged particle beam instrument 100, and illustrates the operation of the sample stage 5 and the relative positions of the various columnar arrangements. To perform SEM observation of the sample 7 being processed by the FIB 2b, the FIB irradiation axis 2a of the FIB column 2 and the EB irradiation axis 1a of the EB column 1 are positioned so as to intersect on the thin sample 7a, the position of which is adjusted by moving the sample stage 5. In other words, the irradiation position of the FIB 2b of the FIB column 2 and the irradiation position of the EB 1b of the EB column 1 coincide on the bulk sample 7.

[0022] The sample stage 5 can be tilted around a tilt axis 8a perpendicular to the EB irradiation axis 1a by a tilt driver 8 serving as a tilt mechanism. That is, the tilt driver 8 serving as a tilt mechanism is driven under the control of the controller 17 and further the sample stage controller 15 to tilt the sample stage 5 as indicated by arrow A. The sample holder (second sample stage) 6 tilts around the tilt axis 8a, which is perpendicular to the electron beam, the focused ion beam, and the normal to the sample placement surface 67S.

[0023] The sample stage 5 can also be rotated in a plane by the rotation drive unit 10 to rotate the bulk sample 7 in that plane. That is, the rotation drive unit 10 as a rotation mechanism is driven under the control of the control unit 17 and further the sample stage control unit 15, and rotates the sample stage 5 in a plane as shown by arrow B. Various types of rotation drive unit 10 as a rotation mechanism can be used, such as a servo motor, and the type is not particularly limited.

[0024] Next, a description will be given of the structure, operation, and function of the sample holder 6 placed on the sample stage 5. The sample holder 6 has a structure that allows it to be tilted independently of the sample stage 5.

[0025] 3 is a schematic perspective view of the sample holder 6. As shown in FIG. 3, the sample holder 6 includes a base 61 disposed directly on the sample stage 5, a holder shaft 62, and a rotating table 63 as a rotating unit. The holder shaft 62 rotates by power supplied from a motor (not shown) that is driven by an external power supply. The plate-shaped rotating table 63 is connected to the holder shaft 62 in the space above the base 61 via a reduction gear or the like, and rotates (turns) in the FR1 direction with the rotation of the holder shaft 62, with the F-axis (flip axis) serving as the shaft axis serving as the rotation center axis.

[0026] The EBSD sample stage 64 is placed on the rotating stage 63 and rotates together with the rotating stage 63. Fig. 4A is a schematic perspective view of the EBSD sample stage 64, and Fig. 4B is a schematic side view of the EBSD sample stage 64.

[0027] As shown in Figures 4A and 4B, the EBSD sample stage 64 includes a bulk sample holder 65 for the sample side surface, a bulk sample holder 66 for the sample plane surface, and a sample piece holder 67. The normal to the bulk sample mounting surface 65s of the bulk sample holder 65 for the sample side surface on which the bulk sample 9 is mounted is perpendicular to the normal to the bulk sample mounting surface 66s of the bulk sample holder 66 for the sample plane surface on which the bulk sample 7 is mounted. The sample piece holder 67 includes multiple sample piece fixing portions and can mount multiple thin sample pieces 7a, 9a. The sample piece holder 67 can mount the thin sample pieces 7a, 9a at an angle relative to the sample mounting surface 66s of the bulk sample holder 66 for the sample plane surface.

[0028] FIG. 4C is a cross section of the sample piece mounting surface 67S of the sample piece holder 67 as seen from the AA direction, illustrating the inclination angle.

[0029] FIG. 4C shows an example in which the inclination angle β of the sample placement surface 67S of the bulk sample holder 67 with respect to the sample placement surface 66S of the bulk sample holder for sample plane 66 is set to 8°.

[0030] Here, the tilt angle β is 8°, but is not limited to this value. This tilt angle β is an angle that can compensate for the rotation angle of the bulk specimen holder 66 and the specimen holder 67 required for EBSD observation and for transferring the specimen from the bulk specimen holders 66 to the specimen holder 67 using the specimen transfer unit (needle) 13. Therefore, EBSD observation, cutting out, and transferring of the specimen can be performed without colliding with structures near the intersection of the electron beam and the focused ion beam, which are surrounded by structures such as the microscope column and detector.

[0031] The case where the flat side of the sample is observed by EBSD, and the bulk sample 7 is cut out and transferred will be described.

[0032] FIG. 5 is a flow chart for explaining the operation of observing the flat surface side of the sample, cutting out the bulk sample 7, and transferring it.

[0033] In step S1 of FIG. 5, the bulk sample 7 is irradiated with a focused ion beam.

[0034] 6A, the observation surface is exposed by irradiating the bulk sample 7 mounted on the sample plane bulk sample holder 66 with a focused ion beam 2b from the FIB column 2 in parallel to the plane of the sample. In step S1, the sample stage 5 is tilted 49° with respect to the irradiation direction of the electron beam 1b, and the EBSD sample stage 64 is tilted −3°.

[0035] Next, in step S2, the observation surface is observed by EBSD.

[0036] 6B, an EB (electron beam) 1b is irradiated onto the bulk sample 7, and backscattered electrons 3e emitted from the bulk sample 7 with a spread of θ1 (70°, for example) centered on a direction tilted by, for example, 100° with respect to the irradiation direction of the electron beam 1b are detected by the EBSD detector 3 for observation (electron backscattering analysis). In step S2, the sample stage 5 is tilted by 59°, and the EBSD sample stage 64 is tilted by 93°.

[0037] Next, in step S3, the focused ion beam 2b is irradiated and a bulk sample 7a including the portion observed by EBSD is cut out.

[0038] 7A and 7B, the bulk sample 7 is irradiated with the focused ion beam 2b, and the sample piece 7a is removed from the bulk sample 7 by the sample transfer unit (needle) 13. In step S3, the sample stage 5 is tilted at an angle of 59°, and the EBSD sample stage 64 is tilted at an angle of 93°.

[0039] Next, in step S4, the sample piece 7a is transferred by the sample transfer unit 13. After the transfer, the sample transfer unit 13 is separated and removed from the sample piece 7a.

[0040] 8A, the sample piece 7a connected to the sample transfer unit (needle) 13 is transferred to the sample piece holder 67, and after the transfer, the sample transfer unit 13 is separated from the sample piece 7a and released. In step S4, the sample stage 5 is tilted at an angle of 49°, and the EBSD sample stage 64 is tilted at an angle of −3°.

[0041] Next, in step S5, the specimen 7a fixed to the specimen holder 67 is irradiated with the focused ion beam 2b to thin the specimen 7a.

[0042] That is, as shown in FIG. 8B, the sample stage 5 is tilted at 49° and the EBSD sample stage 64 is tilted at −3° to thin the sample piece 7a to a thickness that can be observed with a transmission electron microscope.

[0043] Next, we will explain the case where the side of the sample is observed by EBSD, and then the sample piece is cut out and transferred. The operational flow in this case is the same as the operational flow shown in Figure 5. However, although it differs in that the side of the sample is observed instead of the surface side, there are some common operational flows, so we will also refer to each step in Figure 5 for explanation.

[0044] 9A, a focused ion beam 2b is irradiated perpendicularly to the plane of a bulk sample 9 mounted on a bulk sample holder 65 for sample side surfaces to expose the observation surface. In this case, the sample stage 5 is tilted at an angle of 49°, and the EBSD sample stage 64 is tilted at an angle of −3°.

[0045] Next, in step S2, as shown in Fig. 9B, EBSD observation is performed on the side of the sample, which is the observation surface. In EBSD observation, an electron beam is irradiated onto the bulk sample 9, and backscattered electrons emitted from the bulk sample 9 in a 70° spread centered on a direction tilted 100° with respect to the electron beam irradiation direction are detected by the EBSD detector 3. In this case, the sample stage 5 is tilted at 59°, and the EBSD sample stage 64 is tilted at 93°.

[0046] Next, in step S3, as shown in Fig. 10A, a focused ion beam 2b is irradiated to cut out a sample piece 9a including the portion observed by EBSD. As shown in Fig. 10B, a sample transfer unit (needle) 13 is connected to the sample piece 9a, and the sample piece 9a is irradiated with a focused ion beam 2b to separate it from the bulk sample 9. The sample stage 5 is tilted at 49°, and the EBSD sample stage 64 is tilted at -3°.

[0047] Next, in step S4, as shown in Fig. 11A, the sample piece 9a connected to the sample transfer mounting part (needle) 13 is transferred to the sample piece holder 67. The sample stage 5 is tilted at 49°, and the EBSD sample stage 64 is tilted at -3°. After transfer, the sample transfer mounting part (needle) 13 is separated and removed from the sample piece 9a.

[0048] 11B, the specimen 9a fixed to the specimen holder 67 is irradiated with a focused ion beam 2b to thin the specimen 9a. The specimen stage 5 is tilted at an angle of 49°, and the EBSD specimen stage 64 is tilted at an angle of −3°. This thins the specimen 9a to a thickness that can be observed with a transmission electron microscope.

[0049] In the example shown in Figure 4C, the inclination angle of the sample piece mounting surface of the sample piece holder 67 is set to 8°, but the inclination angle can be set to any appropriate value in the range of 1° to 15°.

[0050] According to the first embodiment of the present invention, the charged particle beam instrument 100 is provided with an EBSD sample stage 64 having a bulk sample holder 65 for the sample side, a bulk sample 66 for the sample plane, and a sample piece holder 67, and the sample placement surface 67S of the sample piece holder 67 is inclined at an appropriate angle for sample observation. This makes it possible to process a bulk sample for detailed observation of the bulk sample within the charged particle beam instrument 100, transfer the processed sample, and observe the sample without removing the sample from the charged particle beam instrument 100, thereby shortening the work time for sample observation.

[0051] Since the sample mounting surface 67S of the sample piece holder 67 is inclined at an appropriate angle for sample observation, EBSD observation, cutting out and transferring of the sample piece can be performed near the beam intersection point of the electron beam and the focused ion beam surrounded by structures such as the telescope tube and detector without colliding with the structures.

[0052] That is, according to the first embodiment, it is possible to provide a charged particle beam apparatus and a sample piece transfer method that can shorten the operation time.

[0053] Second Embodiment Next, a second embodiment of the present invention will be described.

[0054] FIG. 12 is a main part of the second embodiment, and is an explanatory view of a sample piece mounting surface rotating part 68 that can rotate the sample piece mounting surface 67S of the sample piece holder 67.

[0055] In the second embodiment, the inclination angle β of the sample mounting surface 67S of the bulk sample holder 67 with respect to the sample installation surface 66S of the sample plane bulk sample holder 66 is set to 0°, and the sample bulk holder 67 is rotated by the sample piece installation surface rotating unit 68 to set the inclination angle of the sample mounting surface 67S with respect to the sample installation surface 66S to an appropriate value in the range of 1° to 15°. The sample bulk holder 67 is configured to be rotatable relative to the sample plane bulk sample holder 66.

[0056] The specimen placement surface rotating unit 68 rotates the specimen bulk holder 67 under the control of the control unit 17 in accordance with the tilt angle command value input from the input unit 16 .

[0057] The tilt angle θ can be set to an appropriate value within the range of 1° to 15°.

[0058] Other configurations of the second embodiment are the same as those of the first embodiment, and therefore illustrations and detailed descriptions thereof will be omitted.

[0059] According to the second embodiment, in addition to being able to obtain the same effect as the first embodiment, it is also possible to change the tilt angle θ of the sample placement surface 67S to an appropriate value in accordance with the tilt angle command value.

[0060] According to the present invention, a portion observed by EBSD within a charged particle beam device can be processed into a sample piece within the charged particle beam device and transferred to a sample piece holder, allowing the sample to be processed and observed without having to be transported outside the charged particle beam device, thereby providing a charged particle beam device and a sample piece transfer method that can shorten the working time.

[0061] The bulk sample holder for the sample side surface 65 and the bulk sample holder for the sample flat surface 66 can be collectively called a bulk sample holder.

[0062] 1...EB column (charged particle beam column), 1a...EB irradiation axis, 1b...EB (electron beam), 2...FIB column (focused ion beam column), 2a...FIB irradiation axis, 2b...FIB, 3...EBSD detector, 5...sample stage, 6...sample holder, 7, 9...bulk sample, 7a, 9a...sample piece, 8...tilt drive unit, 8a...tilt axis, 10...rotation drive unit, 11...EB control unit, 12...FIB control unit, 13...sample transfer unit (needle), 14 Image forming unit, 15 sample stage control unit, 16 input unit, 17 control unit, 18 display unit, 60 sample holder control unit, 61 base, 62 holder shaft, 63 rotating table, 64 EBSD sample stage, 65 bulk sample holder for sample side, 65S, 66S bulk sample mounting surface, 66 bulk sample holder for sample plane, 67 sample piece holder, 67S sample mounting surface, 68 sample piece mounting surface rotating unit, 100 charged particle beam device

Claims

1. A charged particle beam device comprising: a charged particle beam column that irradiates an electron beam; a focused ion beam column that irradiates a focused ion beam; a tiltable first sample stage; a second sample stage that is placed on the first sample stage and can be tilted independently of the first sample stage; an EBSD detector; and a sample transfer unit, wherein the second sample stage has a bulk sample holder that mounts a bulk sample, and a sample piece holder that mounts a sample piece extracted from the bulk sample, and the sample mounting surface of the sample piece holder is inclined at an angle relative to the bulk sample mounting surface of the bulk sample holder.

2. A charged particle beam device according to claim 1, characterized in that the sample mounting surface of the sample piece holder has an inclination angle of any one of 1° to 15° with respect to the bulk sample mounting surface of the bulk sample holder.

3. A charged particle beam apparatus according to claim 1 or 2, characterized in that the bulk sample holder comprises a bulk sample holder for a flat sample surface and a bulk sample holder for a side sample surface, and the normal to the bulk sample mounting surface of the bulk sample holder for a flat sample surface is perpendicular to the normal to the sample mounting surface of the bulk sample holder for a side sample surface.

4. A charged particle beam apparatus according to claim 1 or 2, characterized in that the charged particle beam column is arranged so that the irradiation axis of the electron beam is in the vertical direction, and the second sample stage is tilted around a tilt axis, which is perpendicular to the electron beam, the focused ion beam, and the normal to the sample placement surface.

5. A charged particle beam apparatus according to claim 2, characterized in that it comprises a sample piece mounting surface rotating unit that rotates the sample piece mounting surface of the sample piece holder and sets the tilt angle to any one of 1° to 15°.

6. A sample piece transfer method comprising the steps of: exposing an observation surface of a sample on a bulk sample holder by using a focused ion beam; irradiating the observation surface with an electron beam to observe it; irradiating the sample with the focused ion beam to cut out a sample piece from the sample; and transferring the sample piece to a sample mounting surface of a sample piece holder that is inclined at an angle to the bulk sample mounting surface of the bulk sample holder.

7. A sample piece transfer method as described in claim 6, characterized in that the sample placement surface of the sample piece holder has an inclination angle of any one of 1° to 15° with respect to the bulk sample mounting surface of the bulk sample holder.

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