Charged particle beam apparatus

Abstract

A focused ion beam lens barrel (17) of this charged particle beam device comprises an ion source (41) and an ion optical system (42). The ion optical system (42) comprises an aperture member (54b) having formed therein a plurality of through-holes that are switched in order to cause a portion of the beams (ion beams) of the ions generated by the ion source (41) to pass therethrough. Any of the plurality of through-holes are switched while the optical conditions of the ion optical system (42) are maintained in a prescribed projection mode (second projection mode). The plurality of through-holes include fine round holes for viewing that are disposed in the center of the ion beam, and first rectangular holes for processing and second rectangular holes for viewing and processing that are disposed away from the center of the ion beam.

Description

Technical Field

[0001] The present invention relates to a charged particle beam apparatus.

Background Art

[0002] Conventionally, there is known a beam apparatus that repeatedly executes a process of observing and processing a sample by irradiating an ion beam to form a cross section and a process of acquiring a cross-sectional image by irradiating an electron beam (see, for example, Patent Document 1). Conventionally, there is known a beam apparatus that includes a mask (aperture) having an opening of a desired shape in an optical system and irradiates a sample with a beam in a projection mode in which the beam shape cut by the mask is made to coincide with the processing shape (see, for example, Patent Document 2). For example, in a charged particle beam apparatus equipped with a plasma ion source, a probe current of 100 nA or more can be obtained, and the processing time can be shortened in large-area processing. On the other hand, as the probe current increases, the probe diameter also increases. Furthermore, the region with a low current density outside the main beam becomes larger, and the edge of the cross section obtained by processing is shaved and has a large rounded chamfered shape. When creating a large-area cross section, reducing the probe current to form an edged beam for edging increases the processing time. Therefore, Patent Document 2 is known as a method for forming a beam with a large probe current and an edged beam. In the conventional method, in cross-section processing, the probe current is changed from two levels to three levels, and the processing is performed in order from the larger probe current to achieve edged processing. At this time, it is necessary to leave a finishing allowance in the processing with a large probe current. However, as described above, since the area is large, in order to shorten the processing time, it is necessary to process at a location as close as possible to the desired processing position. In the conventional method of processing with a beam that is made parallel by a focusing lens (CL) without projecting a mask and converged on a sample by an objective lens, since the beam shape is small and spot-like, the processing position can be accurately determined by observing while scanning the sample.

Prior Art Documents

Patent Document

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the beam shape in the projection mode is made into a processing shape, it is large, and it is difficult to accurately determine the processing position by observing on the sample in the same manner as in the prior art. Therefore, a method of switching to the projection mode during processing while using the focusing mode during processing position determination can be considered. When observing and processing a sample with the ion beam of the above-described beam apparatus, if the optical conditions during observation and the optical conditions during processing are switched, there is a risk that the processing position deviates from the desired position without ensuring position reproducibility. For example, when the focusing mode in which the ion beam is made into a substantially parallel beam by a focusing lens and focused on the sample by an objective lens is used as the optical condition during observation, and the optical condition during processing is the projection mode, a problem occurs in that the processing position easily deviates from the desired position due to the lens voltage, the position accuracy of the aperture, and the like.

[0005] An object of the present invention is to provide a charged particle beam apparatus capable of improving the position accuracy of a processing position by a charged particle beam.

Means for Solving the Problems

[0006] In order to solve the above problems, the charged particle beam device according to the present invention includes a charged particle source that generates charged particles, and a diaphragm member having a plurality of through-holes formed therein that are switched to allow a part of the beam of the charged particles generated from the charged particle source to pass through, and an optical system that irradiates a sample with the beam of the charged particles passing through each of the plurality of through-holes. The plurality of through-holes are switched to any one while the optical system maintains a predetermined optical condition, and include at least a first through-hole disposed at the center of the beam of the charged particles and a second through-hole disposed offset from the center of the beam of the charged particles.

[0007] In the above configuration, the plurality of through-holes may include at least the first through-hole, the second through-hole, and a third through-hole that is disposed offset from the center of the beam of the charged particles and has a size in the direction of deviation from the center of the beam of the charged particles that is approximately the same as the size of the first through-hole and a size in a direction orthogonal to the direction of deviation from the center of the beam of the charged particles that is approximately the same as the size of the second through-hole.

[0008] In order to solve the above problems, the charged particle beam device according to the present invention includes a charged particle source that generates charged particles, and a plurality of diaphragm members each having at least one through-hole formed therein to allow a part of the beam of the charged particles generated from the charged particle source to pass through, and an optical system that irradiates a sample with the beam of the charged particles passing through the through-hole of each of the plurality of diaphragm members. The plurality of diaphragm members do not interfere with each other with respect to the passage of the beam of the charged particles, and include at least a first diaphragm member having a first through-hole formed at the center of the beam of the charged particles while the optical system maintains a predetermined optical condition, and a second diaphragm member having a second through-hole formed at a position offset from the center of the beam of the charged particles while the optical system maintains the predetermined optical condition.

[0009] In the above configuration, the at least one through hole formed in the second aperture member includes the second through hole and a third through hole that is displaced from the center of the charged particle beam while the optical system maintains the predetermined optical conditions, and has a size in the direction of displacement from the center of the charged particle beam that is approximately the same as the size of the first through hole, and a size in the direction orthogonal to the direction of displacement from the center of the charged particle beam that is approximately the same as the size of the second through hole.

[0010] In the above configuration, the edge closest to the center of the charged particle beam of each of the second through hole and the third through hole may be linear and parallel to the direction orthogonal to the direction of displacement from the center of the charged particle beam.

[0011] In the above configuration, the optical system includes a condenser lens disposed between the charged particle source and the aperture member to focus the charged particle beam, and an objective lens disposed between the aperture member and the sample to focus the charged particle beam on the sample. The predetermined optical conditions are based on the Köhler illumination method, with the aperture member as the light source by the objective lens, and the charged particle beam is focused on the sample in a beam shape cut by the aperture member. Taking the lens strength when the charged particle beam is focused on a predetermined position of the objective lens by the condenser lens as the reference lens strength, the lens strength of the condenser lens may be set to 0.8 times or more and less than 1.0 times the reference lens strength.

Advantages of the Invention

[0012] According to the present invention, by providing an aperture member formed with a first through hole and a second through hole that can be switched while maintaining the optical conditions, for example, observation and processing can be switched by switching between the first through hole for observation and the second through hole for processing, and the positional accuracy of the processing position by the charged particle beam can be improved.

Brief Description of the Drawings

[0013]

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Figure 10

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Figure 12

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a charged particle beam device 10 according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0015] (Charged Particle Beam Device) FIG. 1 is a diagram showing the configuration of the charged particle beam apparatus 10 in the embodiment. The charged particle beam apparatus 10 includes a sample chamber 11, a sample holder 12, a sample stage 13, an electron beam column 15 and a focused ion beam column 17 fixed to the sample chamber 11. The charged particle beam apparatus 10 includes, as a detector fixed to the sample chamber 11, for example, a secondary charged particle detector 21. The charged particle beam apparatus 10 includes a gas supply unit 23 that supplies gas to the surface of the sample S. The charged particle beam apparatus 10 includes a control device 25 that integrally controls the operation of the charged particle beam apparatus 10 outside the sample chamber 11, and an input device 27 and a display device 29 connected to the control device 25.

[0016] In the following, each axial direction of the X-axis, Y-axis, and Z-axis that are orthogonal to each other in the three-dimensional space is a direction parallel to each axis. For example, the Z-axis direction is parallel to the vertical direction (for example, the vertical direction, etc.) of the charged particle beam apparatus 10. The X-axis direction and the Y-axis direction are parallel to a reference plane (for example, a horizontal plane, etc.) that is orthogonal to the vertical direction of the charged particle beam apparatus 10.

[0017] The sample chamber 11 is formed of a pressure-resistant housing having an airtight structure capable of maintaining a desired reduced pressure state. The sample chamber 11 can be evacuated by an evacuation device (not shown) until the inside reaches a desired reduced pressure state. The sample holder 12 fixes the sample S. The sample stage 13 is disposed inside the sample chamber 11. The sample stage 13 includes a stage 31 that supports the sample holder 12, and a stage drive mechanism 33 that three-dimensionally translates and rotates the stage 31 integrally with the sample holder 12. The stage drive mechanism 33 translates the stage 31 along the axial directions of, for example, the X-axis, Y-axis, and Z-axis. The stage drive mechanism 33 rotates the stage 31 at an appropriate angle around, for example, the axes of a predetermined rotation axis and tilt axis. The rotation axis is, for example, set relative to the stage 31 and is parallel to the vertical direction of the charged particle beam apparatus 10 when the stage 31 is at a predetermined reference position around the axis of the tilt axis. The tilt axis is, for example, parallel to a direction orthogonal to the vertical direction of the charged particle beam apparatus 10. The stage drive mechanism 33 rotates the stage 31, for example, eucentrically around the axes of the rotation axis and tilt axis. The stage drive mechanism 33 is controlled by a control signal output from the control device 25 according to, for example, the operation mode of the charged particle beam apparatus 10.

[0018] The electron beam column 15 irradiates an irradiation target within a predetermined irradiation region inside the sample chamber 11 with an electron beam. The electron beam column 15 faces the stage 31, for example, in an inclined direction in which the emission end portion 15a of the electron beam is inclined at a predetermined angle with respect to the vertical direction of the charged particle beam apparatus 10. The electron beam column 15 is fixed to the sample chamber 11 with the optical axis of the electron beam parallel to the inclined direction. The electron beam column 15 includes an electron source that generates electrons and an electron optical system that focuses and deflects the electrons emitted from the electron source. The electron optical system includes, for example, electromagnetic lenses and deflectors. The electron source and the electron optical system are controlled by a control signal output from the control device 25 according to, for example, the irradiation position and irradiation conditions of the electron beam.

[0019] The focused ion beam column 17 irradiates an irradiation target within a predetermined irradiation region inside the sample chamber 11 with a focused ion beam. The focused ion beam column 17 faces the stage 31 in the vertical direction of the charged particle beam apparatus 10, for example, with the emission end portion 17a of the focused ion beam. The focused ion beam column 17 is fixed to the sample chamber 11 with the optical axis of the focused ion beam parallel to the vertical direction. Details of the focused ion beam column 17 in the embodiment will be described later.

[0020] The optical axes of the electron beam column 15 and the focused ion beam column 17 intersect at a predetermined position P above the sample stage 13, for example. Note that the arrangement of the electron beam column 15 and the focused ion beam column 17 relative to each other may be appropriately interchanged. For example, the electron beam column 15 may be arranged in the vertical direction, and the focused ion beam column 17 may be arranged in an inclined direction or an orthogonal direction inclined with respect to the vertical direction.

[0021] The charged particle beam apparatus 10 can perform imaging of the irradiated portion, various processes (such as etching and trimming) by sputtering, formation of a deposition film, etc., by irradiating while scanning a focused ion beam on the surface of the irradiation target. The charged particle beam apparatus 10 can perform a process of forming a sample piece for transmission observation by a transmission electron microscope (for example, a thin film sample and a needle-shaped sample, etc.) and an analysis sample piece for analysis by an electron beam from the sample S. The charged particle beam apparatus 10 can perform a process of making the sample piece transferred to the sample piece holder into a thin film having a desired thickness suitable for transmission observation by a transmission electron microscope. The charged particle beam apparatus 10 can perform observation of the surface of the irradiation target by irradiating while scanning a focused ion beam or an electron beam on the surface of the irradiation target such as the sample S, the sample piece, and the needle.

[0022] The secondary charged particle detector 21 detects secondary charged particles (secondary electrons and secondary ions) generated from the irradiation target by irradiation with a focused ion beam or an electron beam or the like. The secondary charged particle detector 21 is connected to the control device 25, and the detection signal output from the secondary charged particle detector 21 is transmitted to the control device 25. The charged particle beam apparatus 10 may be provided with other detectors in addition to the secondary charged particle detector 21. The other detectors are, for example, an EDS (Energy Dispersive X-ray Spectrometer) detector, a reflected electron detector, and an EBSD (Electron Back-Scattering Diffraction) detector. The EDS detector detects X-rays generated from the irradiation target by the irradiation of the electron beam. The reflected electron detector detects reflected electrons reflected from the irradiation target by the irradiation of the electron beam. The EBSD detector detects an electron backscattering diffraction pattern generated from the irradiation target by the irradiation of the electron beam. Note that the secondary electron detector and the reflected electron detector that detect secondary electrons among the secondary charged particle detectors 21 may be housed in the housing of the electron beam column 15.

[0023] The gas supply unit 23 is fixed to the sample chamber 11. The gas supply unit 23 includes a gas injection unit (nozzle) disposed facing the stage 31. The gas supply unit 23 supplies etching gas, deposition gas, etc. to the irradiation target. The etching gas selectively promotes the etching of the irradiation target by the focused ion beam according to the material of the irradiation target. The deposition gas forms a deposition film of a deposit such as a metal or an insulator on the surface of the irradiation target. The gas supply unit 23 is controlled by a control signal output from the control device 25 according to the operation mode of the charged particle beam apparatus 10 and the like.

[0024] The control device 25 integrally controls the operation of the charged particle beam apparatus 10 by, for example, a signal output from the input device 27 or a signal generated by a preset automatic operation control process. The control device 25 is a software functional unit that functions when a predetermined program is executed by a processor such as a CPU (Central Processing Unit). The software functional unit is an ECU (Electronic Control Unit) that includes a processor such as a CPU, a ROM (Read Only Memory) that stores the program, a RAM (Random Access Memory) that temporarily stores data, and electronic circuits such as a timer. At least a part of the control device 25 may be an integrated circuit such as an LSI (Large Scale Integration).

[0025] The input device 27 is, for example, a mouse, a keyboard, etc. that output a signal according to an operator's input operation. The display device 29 displays various information of the charged particle beam device 10, image data generated by a signal output from the secondary charged particle detector 21, and a screen for executing operations such as enlargement, reduction, movement, and rotation of the image data.

[0026] (Focused Ion Beam Column) FIG. 2 is a diagram showing the configuration of the focused ion beam column 17 in the embodiment. The focused ion beam column 17 includes an ion source 41 and an ion optical system 42. The ion source 41 and the ion optical system 42 are controlled by a control signal output from the control device 25 according to the irradiation position and irradiation conditions of the focused ion beam, etc. The ion source 41 generates ions. The ion source 41 is, for example, a plasma type ion source by inductive coupling or electron cyclotron resonance (ECR). Note that the ion source 41 may be, for example, a liquid metal ion source using liquid gallium or the like, or a gas field ionization type ion source.

[0027] The ion optical system 42 focuses and deflects a beam of ions (ion beam) extracted from the ion source 41. The ion optical system 42 can be switched to any of a plurality of modes such as a focusing mode and a projection mode, the optical conditions of which will be described later. The ion optical system 42 includes, for example, an extraction electrode 51, a condenser lens 52, a blanker 53, a movable aperture 54, an alignment 55, a stigmator 56, a scanning electrode 57, and an objective lens 58, which are sequentially arranged from the side of the ion source 41 toward the emission end 17a side of the focused ion beam column 17 (that is, the sample S side).

[0028] The extraction electrode 51 extracts ions from the ion source 41 by an electric field generated between the extraction electrode 51 and the ion source 41. The voltage applied to the extraction electrode 51 is controlled, for example, according to the acceleration voltage of the ion beam, and the potential difference between the acceleration voltage applied to the ion source 41 and the voltage applied to the extraction electrode 51 is kept constant. The condenser lens 52 includes, for example, a first condenser lens 52a and a second condenser lens 52b arranged along the optical axis. Each of the first condenser lens 52a and the second condenser lens 52b is an electrostatic lens including, for example, three electrodes arranged along the optical axis. The condenser lens 52 focuses the ion beam extracted from the ion source 41 by the extraction electrode 51. The condenser lens 52 changes the lens strength regarding the degree of focusing of the ion beam by adjusting the voltage applied according to the optical conditions of the focused ion beam column 17.

[0029] The blanker 53, the alignment 55, and the scanning electrode 57 constitute an electrostatic deflector 59 that deflects the ion beam. The stigmator 56 constitutes an aberration corrector for adjusting the beam shape. The blanker 53 includes, for example, a pair of electrodes (blanking electrodes) that are arranged to face each other so as to sandwich the optical axis from both sides in a direction intersecting the traveling direction of the ion beam. The blanker 53 switches the presence or absence of blocking the ion beam. For example, the blanker 53 deflects the ion beam to cause it to collide with a blanking aperture (not shown) to block it, and releases the blocking by not deflecting the ion beam.

[0030] FIG. 3 is a diagram showing the configuration of the movable aperture 54. As shown in FIGS. 2 and 3, the movable aperture 54 includes a drive mechanism 54a and an aperture member 54b. The drive mechanism 54a is controlled by a control signal output from the control device 25 according to the operation mode of the charged particle beam device 10 or the like. For example, the drive mechanism 54a includes an actuator that drives in at least one axial direction. The actuator is a piezoelectric actuator. The actuator drives in an arbitrary one axial direction in a plane intersecting at least the optical axis of the focused ion beam column 17. The actuator drives in the X-axis direction orthogonal to the optical axis of the focused ion beam column 17 to move the aperture member 54b forward and backward in the X-axis direction. The outer shape of the aperture member 54b is, for example, plate-shaped with a plurality of through holes formed along a predetermined direction. The predetermined direction is the driving direction of the drive mechanism 54a, for example, the X-axis direction. The plurality of through holes are switched to allow a part of the ion beam to pass through according to the drive of the aperture member 54b by the drive mechanism 54a. The plurality of through holes are, for example, a circular hole 61 for observation, a first rectangular hole 62 for processing, and a second rectangular hole 63 for observation and processing.

[0031] The diameter r of the circular hole 61 is, for example, a relatively small value of 5 μm or less. The center of the circular hole 61 is arranged to be the same as a first reference position Q1 that coincides with the center of the optical axis (beam center) of the focused ion beam column 17. The outer shape of the first rectangular hole 62 is, for example, a square with a side length greater than the diameter r of the circular hole 61 and not more than 1 mm. The first rectangular hole 62 is displaced by a predetermined distance La in a predetermined direction (e.g., the X-axis direction) from a second reference position Q2 that coincides with the center of the optical axis of the focused ion beam column 17 so as to shield a predetermined range including the center of the optical axis of the focused ion beam column 17 by the aperture member 54b. One side 62a of the four sides (edges) of the first rectangular hole 62 closest to the second reference position Q2 is parallel to a direction orthogonal to the predetermined direction (e.g., the Y-axis direction), and the distance between one side 62a and the second reference position Q2 is the predetermined distance La. The predetermined distance La is, for example, greater than zero and not more than 500 μm. The predetermined distance La is more preferably greater than zero and not more than 50 μm. Also, the predetermined distance La may be, for example, in the range of about 1.2 times to 1.5 times half of the length of the first rectangular hole 62 in the predetermined direction (e.g., the X-axis direction).

[0032] The outer shape of the second rectangular hole 63 is, for example, a rectangle with a short side length approximately the same as the diameter of the circular hole 61 for observation and a long side length approximately the same as the side length of one side of the first rectangular hole 62 for processing. The second rectangular hole 63 is displaced by a predetermined distance La in a predetermined direction (e.g., the X-axis direction) from a third reference position Q3 that coincides with the center of the optical axis of the focused ion beam column 17 so as to shield a predetermined range including the center of the optical axis of the focused ion beam column 17 by the aperture member 54b. One side (long side) 63a of the four sides (edges) of the second rectangular hole 63 closest to the third reference position Q3 is parallel to a direction orthogonal to the predetermined direction (e.g., the Y-axis direction), and the distance between one side 63a and the third reference position Q3 is the predetermined distance La.

[0033] As shown in FIG. 2, each of the alignment 55, the stigmator 56, and the scanning electrode 57 includes, for example, a plurality of electrodes and the like arranged in a cylindrical shape so as to surround the optical axis of the ion beam. The alignment 55 adjusts the orbit of the ion beam so that the ion beam passes through the central axis of the objective lens 28. The stigmator 56 corrects the spherical aberration of the ion beam. The scanning electrode 57 scans the ion beam that has passed through the objective lens 58 over the sample. For example, the scanning electrode 57 raster-scans a rectangular area on the surface of the sample S by applying a deflection voltage for two-dimensional scanning.

[0034] The objective lens 58 is, for example, an electrostatic lens including three electrodes arranged along the optical axis. The objective lens 58 focuses the ion beam on the sample S. The objective lens 58 changes the lens strength regarding the degree of focusing of the ion beam, the size of the beam shape, etc. by adjusting the voltage applied according to the optical conditions of the focused ion beam column 17.

[0035] The ion optical system 42 can switch the optical conditions to any of a plurality of modes such as a focusing mode and a projection mode, for example. In the focusing mode, the ion beam is made substantially parallel without intersecting the trajectory of the ion beam between the condenser lens 52 and the objective lens 58, and the angular spread of the ion beam is adjusted by the movable aperture 54. In the focusing mode, the sample S is scanned by the ion beam that is focused on the sample S by the objective lens 58 and deflected by the electrostatic deflector 59. In the projection mode, based on the Koehler illumination method, which is so-called uniform illumination, the ion beam shaped by the movable aperture 54 corresponding to the field stop is projected onto the sample S without scanning. In the projection mode, the objective lens 58 uses the movable aperture 54 as a light source and focuses the ion beam on the sample S in the beam shape cut out by the movable aperture 54. Note that in the projection mode, scanning may be performed to expand the irradiation range or the like.

[0036] The ion optical system 42 is set, for example, as a projection mode, to a second projection mode in which the applied voltage of the condenser lens 52 is reduced compared to the reference first projection mode. FIG. 4 is a diagram showing an example of the trajectory of the ion beam according to the applied voltage of the condenser lens 52 in the projection mode of the focused ion beam column 17. FIG. 5 is a diagram showing an example of the intensity distribution of the probe current I on the surface of the sample S corresponding to the trajectory of the ion beam shown in FIG. 4. The first trajectory B1 shown in FIG. 4 is the trajectory of the ion beam when the ion beam is focused (brought into focus) on the principal plane (or center) of the objective lens 58 by applying a predetermined voltage V1 to the condenser lens 52 (first projection mode). The second trajectory B2 shown in FIG. 4 is the trajectory of the ion beam when the intensity of focusing the ion beam by the condenser lens 52 is weakened compared to the first projection mode (second projection mode). The voltage V2 applied to the condenser lens 52 in the second projection mode is, for example, 0.8 times or more and less than 1.0 times the predetermined voltage V1 in the first projection mode (0.8×V1≦V2<V1). Taking the lens intensity regarding the degree of focusing of the ion beam by the condenser lens 52 in the first projection mode as the reference lens intensity, the lens intensity of the condenser lens 52 in the second projection mode is 0.8 times or more and less than 1.0 times the reference lens intensity.

[0037] As shown in FIG. 5, the intensity distribution D1 of the probe current I corresponding to the first trajectory B1 in the first projection mode is substantially uniform within a predetermined irradiation range including the irradiation center O on the sample S. The intensity distribution D2 of the probe current I corresponding to the second trajectory B2 in the second projection mode has an increasing tendency from the periphery toward the irradiation center O within an irradiation range smaller than the predetermined irradiation range in the first projection mode. In the intensity distribution D2 of the second projection mode, the intensity of the probe current I at the irradiation center O is larger than that in the intensity distribution D1 of the first projection mode, and the beam intensity near the irradiation center O is stronger.

[0038] The ion optical system 42 switches and selects a plurality of through holes of the movable aperture 54 while maintaining the optical conditions in the second projection mode of the projection mode, for example, when the processing and observation of the sample S are repeatedly performed. FIG. 6 is a diagram showing an example of the position of the aperture member 54b with respect to the beam center C of the movable aperture 54 of the focused ion beam column 17. FIG. 7 is a diagram showing an example of the position of the first rectangular hole 62 for processing with the movable aperture 54 with respect to the beam center C. FIG. 8 is a diagram showing an example of the contour of the processing range on the surface of the sample S corresponding to the position of the first rectangular hole 62 shown in FIG. 7.

[0039] When the ion optical system 42 in the second projection mode performs observation and processing positioning of the sample S, for example, by means of the minute circular hole 61 for observation of the movable aperture 54 shown in FIG. 3, the center of the circular hole 61 is made to coincide with the beam center C by making the first reference position Q1 of the aperture member 54b coincide with the beam center C. When the ion optical system 42 in the second projection mode performs processing of the sample S by means of the first rectangular hole 62 for processing of the movable aperture 54 as shown in FIG. 6, for example, the second reference position Q2 of the aperture member 54b is made to coincide with the beam center C. As a result, the first rectangular hole 62 is displaced by a predetermined distance La from the beam center C in the X-axis direction, and a predetermined range including the beam center C is shielded by the aperture member 54b. When the ion optical system 42 in the second projection mode performs observation or processing of the sample S by means of the second rectangular hole 63 for observation and processing of the movable aperture 54 as in the case shown in FIG. 6, for example, the third reference position Q3 of the aperture member 54b is made to coincide with the beam center C. As a result, the second rectangular hole 63 is displaced by a predetermined distance La from the beam center C in the X-axis direction, and a predetermined range including the beam center C is shielded by the aperture member 54b.

[0040] The embodiments shown in FIGS. 7 and 8 are the same as the state shown in FIG. 6, in which the first rectangular hole 62 for processing of the movable aperture 54 is displaced by a predetermined distance La from the beam center C in the X-axis direction, and a predetermined range including the beam center C is shielded by the aperture member 54b. The first comparative example shown in FIGS. 7 and 8 is a state in which the center of the first rectangular hole 62 for processing of the movable aperture 54 coincides with the beam center C. The second comparative example shown in FIGS. 7 and 8 is a state in which one side 62a of the first rectangular hole 62 for processing of the movable aperture 54 (the side 62a closest to the second reference position Q2 among the four sides of the first rectangular hole 62) coincides with the beam center C in the X-axis direction. As shown in FIG. 8, in the embodiment, compared with the first and second comparative examples, a contour of a processing range having a straight edge E0 near the irradiation center O can be obtained. In the first comparative example, it is not possible to obtain a contour of a processing range having an edge near the irradiation center O. In the second comparative example, a contour of a processing range having a curved edge E2 near the irradiation center O is obtained, and the edge E2 near the irradiation center O is not straight.

[0041] As shown in FIG. 5, in the second projection mode, the beam intensity changes in an increasing trend from the periphery of the irradiation range toward the irradiation center O. Thus, according to an embodiment in which a contour of a processing range having a linear edge E0 near the irradiation center O is obtained as shown in FIG. 8, the linear edge E0 can be efficiently processed with a relatively high beam intensity. In the embodiment, the beam intensity of the ion beam formed by the movable aperture 54 changes in a decreasing trend from the irradiation center O toward the periphery of the irradiation range, so that a groove shape having a slope-shaped bottom surface that gradually becomes shallower from the deepest edge E0 toward the periphery of the irradiation range is obtained by a single beam irradiation without the need for scanning.

[0042] (Observation and Processing Process) FIG. 9 is a diagram showing an example of processing and observation of a sample S by the charged particle beam apparatus 10. Steps S01 and S02 shown in FIG. 9 are examples in which the process of producing and observing a cross-section of the sample S is repeatedly executed, for example, in three-dimensional structural analysis. First, in step S01, the optical conditions of the ion optical system 42 of the focused ion beam column 17 are set to the second projection mode of the projection mode, and the center of the circular hole 61 for observation of the movable aperture 54 is aligned with the beam center C to set the processing position. Then, with the optical conditions of the ion optical system 42 maintained in the second projection mode, the second reference position Q2 with respect to the first rectangular hole 62 for processing of the movable aperture 54 is aligned with the beam center C, and the sample S is etched (rough processed) with the focused ion beam formed by the first rectangular hole 62. As a result, a groove shape having a slope-shaped bottom surface B that gradually becomes shallower from the linear edge E0 toward the periphery of the irradiation range is formed, and a planar cross-section CS is formed by the edge E0.

[0043] Next, in step S02, with the optical conditions of the ion optical system 42 maintained in the second projection mode, the movable aperture 54 is processed and the third reference position Q3 with respect to the second rectangular hole 63 for observation is aligned with the beam center C, and the sample S is etched (finished) with the focused ion beam formed by the second rectangular hole 63. As a result, the planar cross-section CS is finished with a straight edge E0. Note that prior to the finishing by the second rectangular hole 63, the processing position may be confirmed by the circular hole 61 for observation. Next, the cross-section CS is observed by irradiating the cross-section CS with the electron beam from the electron beam column 15. Next, for example, based on a scanning signal or the like, the processing position is fed and moved, and the sample S is newly etched with the focused ion beam formed by the second rectangular hole 63 for processing and observation of the movable aperture 54 to create a new cross-section CS. Next, the new cross-section CS is observed with the electron beam of the electron beam column 15. Thereafter, the creation of the cross-section CS of the sample S with the focused ion beam formed by the second rectangular hole 63 of the movable aperture 54 and the observation of the cross-section CS with the electron beam of the electron beam column 15 are repeatedly executed.

[0044] Steps S01 and S03 shown in FIG. 9 are examples of preparing a sample piece Sp such as a thin sample for transmission observation by a transmission electron microscope from the sample S. After the execution of step S01 described above, in step S03, first, the center of the circular hole 61 for observation of the movable aperture 54 is aligned with the beam center C to set a new machining position. The new machining position is, for example, a position on the opposite side of the irradiation range in the X-axis direction in step S01 with respect to a desired sample piece Sp so as to form a sample piece Sp of a predetermined thickness in the X-axis direction. Then, while maintaining the optical conditions of the ion optical system 42 in the second projection mode, for example, the first rectangular hole 62 is arranged at a position symmetric to the position of the first rectangular hole 62 in step S01 with respect to the beam center C in the X-axis direction. On the opposite side of the irradiation range in step S01 in the X-axis direction with respect to the desired sample piece Sp, the sample S is etched (rough machining) with the focused ion beam formed by the first rectangular hole 62. As a result, also on the opposite side of the irradiation range in step S01 in the X-axis direction with respect to the desired sample piece Sp, a groove shape having a slope-shaped bottom surface B that gradually becomes shallower from the straight edge E0 toward the periphery of the irradiation range is formed, and a planar cross-section CS is formed by the edge E0.

[0045] Note that when setting the machining positions in step 01 and step S03, instead of the circular hole 61 for observation, the second rectangular hole 63 for machining and observation may be used, or marks indicating the machining positions may be machined on both sides of the machining area by the second rectangular hole 63. For example, when the second rectangular hole 63 is used for observation, the short side (width in the X-axis direction) of the second rectangular hole 63 is as small as the diameter of the circular hole 61 for observation, so the beam irradiation range in the X-axis direction becomes narrow, and observation and machining positioning can be accurately performed in the X-axis direction. Also, when the second rectangular hole 63 is used for machining, the long side (width in the Y-axis direction) of the second rectangular hole 63 is as large as one side of the first rectangular hole 62 for machining, so the beam irradiation range in the Y-axis direction becomes wide, and machining can be efficiently performed in a short time in the Y-axis direction. Also, after the execution of the etching (rough machining) in step 01 and step S03, confirmation of the machining position by the circular hole 61 for observation and etching (finish machining) of the sample S by the second rectangular hole 63 may be performed.

[0046] As described above, the charged particle beam apparatus 10 of the embodiment includes a diaphragm member 54b formed with a circular hole 61 for observation, a first rectangular hole 62 for processing, and a second rectangular hole 63 for observation and processing, which can be switched while maintaining the optical conditions of the ion optical system 42. By doing so, the positional accuracy of the processing position by the focused ion beam can be improved. For example, compared with the case of switching a plurality of optical conditions with significantly different optical settings such as the focusing mode during observation and the projection mode during processing according to each of the observation and processing times, the reproducibility of the beam irradiation position can be improved by maintaining the optical conditions. By maintaining the optical conditions of the ion optical system 42 in the projection mode, for example, compared with the focusing mode, a larger range can be efficiently processed by a single beam irradiation without the need for scanning. Even when the optical conditions are in the projection mode, by selecting the minute circular hole 61 for observation, accurate observation and processing positioning can be performed.

[0047] By maintaining the optical conditions in the second projection mode of the projection mode, for example, compared with the first projection mode of uniform illumination, the beam intensity at the irradiation center O increases. Therefore, during observation, the desired beam intensity can be ensured by the circular hole 61 arranged at the beam center C. During processing, while each rectangular hole 62, 63 is arranged offset from the beam center C, and each linear side 62a, 63a forming the linear edge E0 is arranged near the beam center C, cross-sectional processing can be efficiently performed.

[0048] (Modification example) Hereinafter, a modification example of the embodiment will be described. For the same parts as those in the above-described embodiment, the same reference numerals will be given and the description will be omitted or simplified.

[0049] In the above-described embodiment, it is assumed that the plurality of through-holes of the aperture member 54b include the first rectangular hole 62 for processing and the second rectangular hole 63 for observation and processing. However, the present invention is not limited to this, and through-holes having other shapes than rectangular holes may be included. For example, instead of the first rectangular hole 62, a through-hole having an appropriate shape including at least one straight side 62a closest to the second reference position Q2 may be formed. For example, instead of the second rectangular hole 63, a through-hole having an appropriate shape including at least one straight side 63a closest to the third reference position Q3 may be formed.

[0050] In the above-described embodiment, the ion optical system 42 of the focused ion beam column 17 is provided with one movable aperture 54. However, the present invention is not limited to this, and a plurality of movable apertures that do not interfere with each other regarding the passage of the ion beam may be provided. FIG. 10 is a diagram showing the configuration of a focused ion beam column 17A in a modified example of the embodiment. FIG. 11 is a diagram showing the configuration of a first movable aperture 71 of the focused ion beam column 17A in the modified example. FIG. 12 is a diagram showing the configuration of a second movable aperture 72 of the focused ion beam column 17A in the modified example. As shown in FIG. 10, the ion optical system 42A of the focused ion beam column 17A in the modified example includes, as a plurality of movable apertures, for example, a first movable aperture 71 and a second movable aperture 72 arranged along the optical axis. The first movable aperture 71 includes a first drive mechanism 71a and a first aperture member 71b. The second movable aperture 72 includes a second drive mechanism 72a and a second aperture member 72b. Each of the first drive mechanism 71a and the second drive mechanism 72a includes an actuator that drives in at least one axial direction (for example, the X-axis direction). The outer shape of each of the first aperture member 71b and the second aperture member 72b is, for example, plate-shaped with a plurality of through-holes formed along a predetermined direction. The predetermined direction is the driving direction of each of the drive mechanisms 71a and 72a, and is, for example, the X-axis direction. The plurality of through-holes are switched to allow a part of the ion beam to pass through in accordance with the driving of each of the aperture members 71b and 72b by the drive mechanisms 71a and 72a.

[0051] As shown in FIG. 11, the plurality of through holes of the first aperture member 71b are, for example, a first circular hole 81 and a second circular hole 82 for observation, and a third circular hole 83 for ion beam passage. The first circular hole 81 corresponds to the circular hole 61 of the embodiment. The diameter r1 of the first circular hole 81 is a relatively small value of, for example, 5 μm or less. The center of the first circular hole 81 is arranged to be the same as a first reference position Q11 that is made to coincide with the center (beam center) of the optical axis of the focused ion beam column 17. The diameter r2 of the second circular hole 82 is larger than the diameter r1 of the first circular hole 81, for example. The center of the second circular hole 82 is arranged to be the same as a second reference position Q12 that is made to coincide with the center (beam center) of the optical axis of the focused ion beam column 17. The diameter r3 of the third circular hole 83 is sized to not block the ion beam passing through each of at least the third rectangular hole 92 and the fourth rectangular hole 93 of the second aperture member 72b described later. The center of the third circular hole 83 is arranged to be the same as a third reference position Q13 that is made to coincide with the center (beam center) of the optical axis of the focused ion beam column 17.

[0052] As shown in FIG. 12, the plurality of through holes of the second aperture member 72b are, for example, a fourth circular hole 91 for ion beam passage, a third rectangular hole 92 for processing, and a fourth rectangular hole 93 for observation and processing. The radius r4 of the fourth circular hole 91 is sized to not block the ion beam passing through each of at least the first circular hole 81 and the second circular hole 82 of the first aperture member 71b. The center of the fourth circular hole 91 is arranged to be the same as a fourth reference position Q21 that is made to coincide with the center (beam center) of the optical axis of the focused ion beam column 17. The third rectangular hole 92 and the fourth rectangular hole 93 correspond to the first rectangular hole 62 and the second rectangular hole 63 of the embodiment.

[0053] The outer shape of the third rectangular hole 92 is the same as that of the first rectangular hole 62 of the embodiment. The third rectangular hole 92 is displaced by a predetermined distance La in a predetermined direction (for example, the X-axis direction) from a fifth reference position Q22 that is aligned with the center of the optical axis of the focused ion beam column 17 so as to shield a predetermined range including the center of the optical axis of the focused ion beam column 17 by the aperture member 72b. One side 92a of the four sides (edges) of the third rectangular hole 92 that is closest to the fifth reference position Q22 is parallel to a direction orthogonal to the predetermined direction (for example, the Y-axis direction), and the distance between one side 92a and the fifth reference position Q22 is the predetermined distance La.

[0054] The outer shape of the fourth rectangular hole 93 is the same as that of the second rectangular hole 63 of the embodiment. The fourth rectangular hole 93 is displaced by a predetermined distance La in a predetermined direction (for example, the X-axis direction) from a sixth reference position Q23 that is aligned with the center of the optical axis of the focused ion beam column 17 so as to shield a predetermined range including the center of the optical axis of the focused ion beam column 17 by the aperture member 72b. One side (long side) 93a of the four sides (edges) of the fourth rectangular hole 93 that is closest to the sixth reference position Q23 is parallel to a direction orthogonal to the predetermined direction (for example, the Y-axis direction), and the distance between one side 93a and the sixth reference position Q23 is the predetermined distance La.

[0055] During observation, the ion optical system 42A positions the first circular hole 81 or the second circular hole 82 of the first aperture member 71b at the center of the optical axis, and positions the fourth circular hole 91 of the second aperture member 72b at the center of the optical axis. Alternatively, under the conditions of the second projection mode, the ion optical system 42A positions the first circular hole 81 or the second circular hole 82 of the first aperture member 71b at the center of the optical axis, and may displace the third rectangular hole 92 or the fourth rectangular hole 93 of the second aperture member 72b by a predetermined distance La in a predetermined direction (e.g., the X-axis direction, etc.) from the center of the optical axis. During processing, the ion optical system 42A positions the third circular hole 83 of the first aperture member 71b at the center of the optical axis, and displaces the third rectangular hole 92 or the fourth rectangular hole 93 of the second aperture member 72b by a predetermined distance La in a predetermined direction (e.g., the X-axis direction, etc.) from the center of the optical axis. Note that, as described above, when the third rectangular hole 92 or the fourth rectangular hole 93 of the second aperture member 72b has already been displaced by a predetermined distance La in a predetermined direction (e.g., the X-axis direction, etc.) from the center of the optical axis during observation, the processing beam can be switched by moving the third circular hole 83 of the first aperture member 71b without moving the second aperture member 72b during processing, so that the processing position can be determined with good reproducibility. Note that, during observation, the ion optical system 42A may move the second aperture member 72b to a position where it does not interfere with the ion beam, and during processing, may move the first aperture member 71b to a position where it does not interfere with the ion beam.

[0056] In the above-described embodiment, the charged particle beam apparatus 10 is provided with the electron beam column 15 and the focused ion beam column 17, but is not limited thereto. For example, the charged particle beam apparatus 10 may be provided with only the focused ion beam column 17 without the electron beam column 15.

[0057] Embodiments of the present invention are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0058] 10... Charged particle beam apparatus, 11... Specimen chamber, 12... Specimen holder, 13... Specimen stage, 15... Electron beam column, 17, 17A... Focused ion beam column, 21... Secondary charged particle detector, 23... Gas supply unit, 25... Control device, 27... Input device, 29... Display device, 41... Ion source (charged particle source), 42, 42A... Ion optical system, 52... Condenser lens, 54... Movable aperture, 54b... Aperture member, 58... Objective lens, 61... Circular hole (first through hole), 62... First rectangular hole (second through hole), 62a... Side (edge), 63... Second rectangular hole (third through hole), 63a... Side (edge), 71... First movable aperture, 71b... First aperture member, 72... Second movable aperture, 72b... Second aperture member, 81... First circular hole (first through hole), 82... Second circular hole, 83... Third circular hole, 91... Fourth circular hole, 92... Third rectangular hole (second through hole), 92a... Side (edge), 93... Fourth rectangular hole (third through hole), 93a... Side (edge), C... Beam center, S... Specimen.

Claims

1. A charged particle source that generates charged particles, and an aperture member having a plurality of through-holes that are switched to allow a part of the beam of the charged particles generated from the charged particle source to pass through, and an optical system that irradiates a sample with the beam of the charged particles passing through each of the plurality of through-holes, comprising: the plurality of through-holes are switched to any one while the optical system maintains the optical conditions of a predetermined projection mode, and include at least a first through-hole for observation disposed at the center of the beam of the charged particles and a second through-hole for processing disposed offset from the center of the beam of the charged particles, A charged particle beam apparatus characterized by this.

2. The plurality of through-holes include at least the first through-hole, the second through-hole, and a third through-hole for observation and processing that is disposed offset from the center of the beam of the charged particles and has a size in the direction of deviation from the center of the beam of the charged particles that is approximately the same as the size of the first through-hole and a size in the direction orthogonal to the direction of deviation from the center of the beam of the charged particles that is approximately the same as the size of the second through-hole, including: The charged particle beam apparatus according to claim 1, characterized by this.

3. A charged particle source that generates charged particles, and an optical system that has a plurality of aperture members each having at least one through-hole that allows a part of the beam of the charged particles generated from the charged particle source to pass through, and irradiates a sample with the beam of the charged particles passing through the through-hole of each of the plurality of aperture members, comprising: the plurality of aperture members do not interfere with each other with respect to the passage of the beam of the charged particles, and include at least a first aperture member having a first through-hole for observation disposed at the center of the beam of the charged particles while the optical system maintains the optical conditions of a predetermined projection mode, and a second aperture member having a second through-hole for processing disposed offset from the center of the beam of the charged particles while the optical system maintains the optical conditions of the predetermined projection mode, comprising: A charged particle beam apparatus characterized by this.

4. The at least one through hole formed in the second aperture member is displaced from the center of the beam of the charged particles while the optical system maintains the optical conditions of the predetermined projection mode, and is arranged such that the size in the direction of displacement from the center of the beam of the charged particles is approximately the same as the size of the first through hole, and the size in the direction orthogonal to the direction of displacement from the center of the beam of the charged particles is approximately the same as the size of the second through hole, and is a third through hole for observation and processing. comprising The charged particle beam apparatus according to claim 3, characterized in that.

5. The edge closest to the center of the beam of the charged particles in each of the second through hole and the third through hole is linear and parallel to the direction orthogonal to the direction of displacement from the center of the beam of the charged particles. The charged particle beam apparatus according to claim 2 or claim 4, characterized in that.

6. A charged particle source for generating charged particles, An aperture member having a plurality of through holes formed therein for switching to allow a part of the beam of the charged particles generated from the charged particle source to pass through, and an optical system for irradiating the sample with the beam of the charged particles passing through each of the plurality of through holes. comprising The plurality of through holes are switched to any one while the optical system maintains predetermined optical conditions, and include at least a first through hole for observation disposed at the center of the beam of the charged particles and a second through hole for processing disposed displaced from the center of the beam of the charged particles. The optical system A condenser lens disposed between the charged particle source and the aperture member for focusing the beam of the charged particles, An objective lens disposed between the aperture member and the sample for focusing the beam of the charged particles on the sample. comprising The predetermined optical conditions Based on the Köhler illumination method, using the aperture member as a light source by the objective lens, focusing the beam of the charged particles on the sample in a beam shape cut out by the aperture member, and setting the lens strength of the condenser lens to 0.8 times or more and less than 1.0 times the reference lens strength, where the lens strength when the beam of the charged particles is focused at a predetermined position of the objective lens by the condenser lens is used as the reference lens strength. The charged particle beam apparatus characterized in that.

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