Charged particle beam device and positioning method for same

Abstract

When observing an observation region of a sample, a computer system of this charged particle beam device positions a stage on which the sample is disposed at an eucentric height on the basis of an observation image acquired from an irradiation resultant matter generated by irradiating the observation region with an ion beam and an electron beam. Next, the computer system changes the tilt of the stage from a horizontal state to a tilted state in which the stage faces the electron beam. On the basis of an observation image acquired from an irradiation resultant matter generated by irradiating the observation region with the ion beam and an observation image acquired from an irradiation resultant matter generated by irradiating the observation region with the electron beam facing the stage, a movement amount for moving the observation region to a position where the ion beam and the electron beam intersect with each other is calculated, and the position of the stage is changed in accordance with the calculated movement amount.

Description

Charged particle beam apparatus and positioning method thereof

[0001] This disclosure relates to technologies such as charged particle beam devices.

[0002] Scanning electron microscopes equipped with focused ion beam devices are known (see Patent Documents 1 and 2 below).

[0003] Japanese Patent Publication No. 4567487, Japanese Unexamined Patent Publication No. 2021-51922

[0004] In the scanning electron microscope described above, scanning the sample surface with a focused ion beam device may damage the sample surface. Therefore, to avoid causing unnecessary damage to the sample, the scanning electron microscope requires that the sample is positioned by alignment and stage movement, and that the ion beam is directly facing the stage when processing the sample surface.

[0005] Such positioning needs to be performed with high precision. To achieve high-precision positioning, the cross-point where the irradiation position of the beam from the focused ion beam system onto the sample surface intersects with the irradiation position of the electron beam from the scanning electron microscope must coincide whether the stage is horizontal or tilted. For this to happen, the eucentric height must also be calculated accurately. However, conventional eucentric height calculations have involved, for example, adjusting the height of the stage. As a result, when the stage is rotated around the T-axis used to tilt the stage as the center of rotation, a discrepancy may occur between the ion beam irradiation position and the electron beam irradiation position, and this discrepancy caused by the tilt of the stage cannot be corrected. In other words, when the stage is tilted, the irradiation position shifts from the cross-point. If the cross-point shifts between when the stage is horizontal and when it is tilted, the scanning electron microscope will not be able to perform high-precision positioning.

[0006] The purpose of this disclosure is to provide a technology that enables high-precision positioning.

[0007] A typical embodiment of this disclosure has the following configuration. A charged particle beam apparatus of one embodiment includes a stage on which a sample with a defined observation area is placed; a stage moving mechanism on which the position of the stage in the height direction and in the direction intersecting the height direction, the rotation of the stage, and the tilt of the stage can be changed; a first optical system for irradiating the sample with a first beam; a second optical system for irradiating the sample with a second beam at a different angle from the first beam; and a computer system for controlling the stage moving mechanism, the first optical system, and the second optical system, and for acquiring an observation image from the irradiation result produced when the first beam and the second beam irradiate the sample. When the stage is in a horizontal state, the computer system calculates a first amount of movement to move the stage so that the observation area is located at the intersection of the first beam and the second beam, based on a first observation image obtained from the resulting irradiated object when the first beam, which is directly facing the stage, irradiates the observation area and a second observation image obtained from the resulting irradiated object when the second beam irradiates the observation area and when the stage is in a horizontal state. The computer system then changes the position of the stage according to the first amount of movement, and at the changed position, controls the stage movement mechanism to change the inclination of the stage from the horizontal state to an inclined state where the stage faces the light source of the second beam. When the stage is in the inclined state, the computer system calculates a second amount of movement to move the stage so that the observation area is located at the intersection of the first beam and the second beam, based on a third observation image obtained from the resulting irradiated object when the first beam irradiates the observation area and a fourth observation image obtained from the resulting irradiated object when the second beam irradiates the observation area and when the stage is in a horizontal state. The computer system then changes the position of the stage according to the second amount of movement.

[0008] A charged particle beam apparatus according to one embodiment includes a stage on which a sample with a defined observation area is placed; a stage moving mechanism capable of changing the position of the stage in the height direction and in the direction intersecting the height direction, the rotation of the stage, and the tilt of the stage; a first optical system for irradiating the sample with a first beam; a second optical system for irradiating the sample with a second beam at a different angle from the first beam; and a computer system for controlling the stage moving mechanism, the first optical system, and the second optical system, and for acquiring observation images from the irradiation results produced when the first beam and the second beam irradiate the sample. The positioning method for the charged particle beam apparatus includes the steps of: calculating a first amount of movement to move the stage so that the observation area is located at the intersection of the first beam and the second beam, based on a first observation image obtained from the irradiation result produced when the first beam facing the stage irradiates the observation area and a second observation image obtained from the irradiation result produced when the second beam irradiates the observation area, when the stage is in a horizontal position; changing the position of the stage according to the first amount of movement; and controlling the stage movement mechanism at the changed position. The method includes the steps of: changing the inclination of the stage from a horizontal state to an inclined state in which the stage faces the light source of the second beam; calculating a second amount of movement for moving the stage so that the observation area is moved to a position where the first beam and the second beam intersect, based on a third observation image obtained from the irradiated object produced when the first beam is irradiated onto the observation area and a fourth observation image obtained from the irradiated object produced when the second beam is irradiated onto the observation area, when the stage is in the inclined state; and changing the position of the stage according to the second amount of movement.

[0009] According to a representative embodiment of this disclosure, a technology is available that enables high-precision positioning in a charged particle beam apparatus. Other issues, configurations, and effects are described in the embodiments for carrying out the invention.

[0010] This figure shows an example of the configuration of the charged particle beam apparatus of the first embodiment. This figure shows an example of the stage movement mechanism of the first embodiment. This figure is for explaining the ideal irradiation position in the related technology. This figure shows the observation image when the T-axis rotation angle is 0 degrees in the related technology. This figure shows the observation image when the T-axis rotation angle is 0 degrees in the related technology. This figure shows the observation image when the T-axis rotation angle is a predetermined angle in the related technology. This figure shows the observation image when the T-axis rotation angle is a predetermined angle in the related technology. This figure is for explaining related technology 1. This figure is for explaining related technology 1. This figure is for explaining related technology 2. This figure is for explaining technical matters that cannot be solved in the related technology. This figure is for explaining technical matters that cannot be solved in the related technology. This figure is for explaining technical matters that cannot be solved in the related technology. This figure is for explaining technical matters that cannot be solved in the related technology. This is a flowchart of an example of the process of aligning the cross point CP and the observation target OT in the first embodiment. This figure is for explaining the mechanism for calculating the first movement amount in the first embodiment. This figure is for explaining the mechanism for calculating the second movement amount in the first embodiment. This figure is for explaining the process of calculating the offset amount of the beam offset in the first modified example of the first embodiment. This figure illustrates the process of calculating a second amount of movement to return the object of observation to the cross point in the first modified example of the first embodiment. This figure shows an example of an observation image at 0 degrees T-axis in the second modified example of the first embodiment. This figure shows an example of an observation image at 0 degrees T-axis in the second modified example of the first embodiment. This figure shows an example of an observation image at θ degrees T-axis in the second modified example of the first embodiment. This figure shows an example of an observation image at θ degrees T-axis in the second modified example of the first embodiment. This figure shows an example of a table storing mapping information in the second embodiment. This figure shows an example of a display of mapping information in the second embodiment. This figure shows an example of a table storing mapping information with an added offset amount in the modified example of the second embodiment. This figure shows an example of a table storing mapping information with an added Z-direction movement amount in the third embodiment.This figure shows an example of a stage movement mechanism in a modified version of the third embodiment. This figure illustrates the method for positioning the object to be observed in the embodiment. This figure illustrates the method for positioning the object to be observed in the embodiment. This figure illustrates the method for positioning the object to be observed in the embodiment. This figure illustrates the method for positioning the object to be observed in the embodiment.

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same parts are generally denoted by the same reference numerals, and repeated descriptions are omitted. In the drawings, the representation of components may not show their actual location, size, shape, extent, etc., in order to facilitate understanding of the invention.

[0012] In explanations, when describing program-based processing, the focus may be on the program, functions, or processing units. However, the main hardware component is the processor, or a controller, device, computer system, or other system composed of such a processor. A computer system, using resources such as memory and communication interfaces as appropriate, executes processing according to the program read into memory. This realizes the specified functions and processing units. A processor is composed of semiconductor devices such as a CPU / MPU or GPU. Processing is not limited to software program processing; it can also be implemented using dedicated circuits. Applicable dedicated circuits include FPGAs, ASICs, CPLDs, etc.

[0013] The program may be pre-installed as data on the target computer system, or it may be distributed as data from the program source to the target computer system. The program source may be a program distribution server on a communication network, or a non-transient computer-readable storage medium, such as a memory card or disk. The program may consist of multiple modules. The computer system may consist of multiple devices. The computer system may consist of a client-server system, a cloud computing system, an IoT system, etc. Various types of data and information are composed of structures such as tables and lists, but are not limited to these. Representations such as identification information, identifiers, IDs, names, and numbers are interchangeable.

[0014] <Configuration of Charged Particle Beam Apparatus> Figure 1 shows an example of the configuration of the charged particle beam apparatus 10. As shown in Figure 1, the charged particle beam apparatus 10 includes a sample chamber 11, a stage 12, a stage movement mechanism 13, a focused ion beam irradiation optical system 14, an electron beam irradiation optical system 15, a detector 16, a gas supply unit 17, a needle 18, a needle drive mechanism 19, a display device 21, a computer system 22, and an input device 23.

[0015] The sample chamber 11 is a vacuum chamber capable of maintaining a vacuum inside where the sample is placed. The stage 12 fixes the sample S, sample piece Q, etc. inside the sample chamber 11. The stage moving mechanism 13 drives the stage 12.

[0016] The focused ion beam irradiation optical system 14 irradiates the target to be irradiated with an ion beam IB within a predetermined irradiation area (i.e., scanning range) inside the sample chamber 11. The focused ion beam irradiation optical system 14 includes an ion source, extraction electrodes, lenses, and apertures. The target to be irradiated by the focused ion beam irradiation optical system 14 is the observation area defined by the sample S, sample piece Q, and needle 18 fixed to the stage 12.

[0017] The electron beam irradiation optical system 15 irradiates the target to be irradiated with an electron beam EB within a predetermined irradiation area inside the sample chamber 11. The electron beam irradiation optical system 15 includes an electron source, extraction electrodes, lenses, and apertures. The target to be irradiated by the electron beam irradiation optical system 15 is the observation area defined by the sample S, sample piece Q, and needle 18 fixed to the stage 12.

[0018] The ion beam IB emitted from the focused ion beam irradiation optical system 14 and the electron beam EB emitted from the electron beam irradiation optical system 15 are irradiated onto the stage 12 at different angles.

[0019] The detector 16 detects irradiation results (secondary electrons, secondary ions, and X-rays, etc.) R generated from the irradiated object by the irradiation of a charged particle beam (i.e., an ion beam IB or an electron beam EB). The gas supply unit 17 is equipped with a gas supply source. The charged particle beam apparatus 10 supplies gas G to the surface of the irradiated object.

[0020] The needle 18 picks up a sample piece Q from the sample S fixed to the stage 12, holds the sample piece Q, and places it in the sample piece holder P. The needle drive mechanism 19 drives the needle 18 to transport the sample piece Q.

[0021] The display device 21 displays observational image data based on the irradiation result R detected by the detector 16. The computer system 22 controls the entire charged particle beam apparatus 10. The input device 23 is, for example, a mouse or keyboard.

[0022] The charged particle beam apparatus 10 can perform various sputtering processes (such as etching) and deposition film formation by scanning the surface of the target object with an ion beam IB. The charged particle beam apparatus 10 can perform processing to form a sample piece Q (e.g., a thin section, a needle-shaped sample, etc.) for transmission observation using a transmission electron microscope from a sample S. The charged particle beam apparatus 10 can process the sample piece Q, which is placed in the sample piece holder P, into a thin film of a desired thickness (e.g., 10 to 20 nm, etc.) suitable for transmission observation using a transmission electron microscope. The charged particle beam apparatus 10 can perform observation of the surface of the target object, such as the sample piece Q and the needle 18, by scanning the surface with an ion beam IB or an electron beam EB.

[0023] <Stage Movement Mechanism> Figure 2 shows an example of a stage movement mechanism. In this embodiment, the stage movement mechanism 13 can move the stage in the Z direction (height direction), the Y direction intersecting the Z direction (orthogonal in this embodiment), the X direction, and the X direction intersecting the Y direction (longitudinal direction of the stage 12). Furthermore, the stage movement mechanism 13 can rotate the disc-shaped stage in the circumferential direction (hereinafter referred to as the "R direction"). In addition, the stage movement mechanism 13 can rotate the entire stage movement mechanism 13 in the rotational direction (hereinafter referred to as the "T-axis rotation direction"), thereby tilting the upper surface of the stage 12. Figure 2 shows the X direction, Y direction, and Z direction. Also, arrow RA indicates the R direction in which the stage 12 rotates, and arrow TA indicates the T-axis rotation direction in which the stage 12 rotates around the T-axis.

[0024] As shown in Figure 2, the stage movement mechanism 13 includes a stage 12. The stage 12 has a disc shape with an edge, and by accommodating the sample S etc. on the disc surface and edge, it is possible to hold the sample S etc. The stage 12 is provided on the support member 12a via a rotating part 12b. The rotating part 12b is provided in the center of the stage 12 and has an R axis extending in the Z direction. The rotating part 12b includes a rotating mechanism that rotates the stage 12 in the R direction (circumferential direction) around the R axis as shown by arrow RA.

[0025] The support member 12a is supported by the Z-direction drive unit 30. Although not shown in the figure, the Z-direction drive unit 30 has a moving mechanism for moving the support member 12a in the Z direction. Although not shown in the figure, the moving mechanism has, for example, a support portion at an end portion within the Z-direction moving portion and a lifting portion that extends in the X direction from the support portion to support the support member 12a. The Z-direction drive unit 30 moves the support member 12a, that is, the stage 12, in the Z direction by operating the lifting portion starting from the support portion.

[0026] Below the Z-direction drive unit 30, a Y-direction drive unit 31 is provided. The Y-direction drive unit 31 has a Y-axis 32 that extends along the Y direction. When the Y-direction drive unit 31 moves along the Y-axis 32, the Z-direction drive unit 30 and the stage 12 are moved in the Y direction.

[0027] Below the Y-direction drive unit 31, an X-direction drive unit 33 is provided. The X-direction drive unit 33 has an X-axis 34 that extends along the X direction. When the X-direction drive unit moves along the X-axis 34, the Y-direction drive unit 31, the Z-direction drive unit 30, and the stage 12 are moved in the X direction.

[0028] A T-axis rotation drive unit 35 is provided so as to sandwich the X-direction drive unit 33 in the X direction. The T-axis rotation drive unit 35 has plate portions 36 fixed to both end portions of the X-direction drive unit 33. A rotation portion 37 is provided on the upper portion of the plate portion 36. The rotation portion 37 is fixed to a T-axis portion 39 via a gear 38. The T-axis portion 39 has a T-axis that extends in the X direction. The rotation portions 37 provided at both upper end portions of the X-direction drive unit 33 are fixed to a housing not shown in the figure. The housing not shown in the figure can operate the X-direction drive unit 33, the Y-direction drive unit 31, the Z-direction drive unit 30, and the stage 12 integrally. Therefore, when the T-axis of the T-axis rotation drive unit 35 rotates, the gear 38 rotates according to the amount of rotation. The rotation portion 37 rotates according to the rotation of the gear 38. When the rotation portion 37 rotates, the X-direction drive unit 33, the Y-direction drive unit 31, the Z-direction drive unit 30, and the stage 12 rotate in the T-axis rotation direction indicated by the arrow TA.

[0029] In this way, the stage movement mechanism 13 can freely change the stage 12 in the X direction, Y direction, Z direction, R rotation direction, and T-axis rotation direction. Therefore, the computer system 22 can freely position the observation target (observation region) of the sample S disposed on the stage 12 with respect to the irradiation direction of the ion beam IB and the irradiation direction of the electron beam EB. In the present embodiment, the T-axis is provided along the longitudinal direction of the stage 12, but it is not limited thereto. The T-axis may be provided so as to be at least orthogonal to the plane formed by the ion beam IB and the electron beam EB. In this case, the direction intersecting the above-described height direction may be any direction orthogonal to the axial direction of the T-axis.

[0030] <Related Technology Explanation> Next, the related technology will be described. First, the ideal irradiation positions of the focused ion beam irradiation optical system 14 and the electron beam irradiation optical system 15 will be described. FIG. 3 is a diagram for explaining the ideal irradiation position.

[0031] As shown in FIG. 3, when the T-axis rotation of the stage 12 is 0 degrees, that is, when the stage 12 is not tilted, the position where the ion beam IB irradiated from the focused ion beam irradiation optical system 14 is irradiated onto the surface 12f0 of the stage 12, and when the T-axis rotation of the stage 12 is a predetermined angle, that is, when the stage 12 is tilted, the position where the electron beam EB irradiated from the electron beam irradiation optical system 15 is irradiated onto the upper surface 12ft of the stage 12 coincide with the T-axis rotation center position C1. Furthermore, the irradiation position of the ion beam IB, the irradiation position of the electron beam EB, the T-axis rotation center position C1, and the observation target of the sample S are all at the same position. The position where the ion beam IB and the electron beam EB intersect is referred to as a cross point CP. The observation target defined for the sample S is preset in the computer system 22.

[0032] The observation image displayed on the display device 21 will be described in an ideal state where the irradiation position of the ion beam IB, the irradiation position of the electron beam EB, the T-axis rotation center position C1, and the observation target of the sample S are all in the same position. Here, the observation target is a hole H provided in the sample S (see Figure 4A, etc., described later). In a top view, the hole H has a shape in which the upper sides of two trapezoids are connected, and is formed as a depression in the sample S.

[0033] Figures 4A and 4B show the observed images when the T-axis rotation angle is 0 degrees. Figure 4A is the observed image V captured by the electron beam irradiation optical system 15. ＳＥＭ The value is 0, and Figure 4B shows the observation image V captured by the focused ion beam irradiation optical system 14. ＦＩＢ It is 0. Figures 5A and 5B show the observed images when the T-axis rotation angle is a predetermined angle. Figure 5A is the observed image V captured by the electron beam irradiation optical system 15. ＳＥＭ θ is the value, and Figure 5B shows the observation image V captured by the focused ion beam irradiation optical system 14. ＦＩＢ θ. The observed image is acquired within a predetermined field of view by the focused ion beam irradiation optical system 14 and the electron beam irradiation optical system 15.

[0034] Figure 4A shows an observation image V of the sample S viewed from an oblique angle by the electron beam irradiation optical system 15. ＳＥＭ It is 0. Therefore, the hole H provided in the sample S is photographed at an angle. Consequently, the trapezoidal hole H is displayed as distorted. On the other hand, Figure 4B is an observation image V of the sample S viewed from directly above by the focused ion beam irradiation optical system 14. ＦＩＢ It is 0. Therefore, the hole H in the sample S is photographed from directly above. Consequently, the shape of the hole H is accurately displayed.

[0035] Figure 5A is an observation image V of the sample S viewed from directly above using the electron beam irradiation optical system 15. ＳＥＭ θ. Therefore, the hole H provided in the sample S is photographed from directly above. Consequently, the shape of the hole H provided in the sample S is accurately displayed. On the other hand, Figure 5B is an observation image V of the sample S viewed from an oblique angle by the focused ion beam irradiation optical system 14. ＦＩＢThe angle is θ. Therefore, the hole H in the sample S is photographed at an angle. Consequently, the hole H in the sample S appears distorted in the image.

[0036] <Related Technologies> Next, related technologies will be explained. Related technologies are techniques for correcting discrepancies that occur between the cross point CP of the ion beam IB and electron beam EB and the actual irradiation position in the height direction (Z direction). Here, the discrepancy occurs, for example, due to manufacturing errors during the manufacturing process of the charged particle beam apparatus 10. Below, two techniques for adjusting the height of the stage 12 will be explained as related technology 1 and related technology 2.

[0037] <Related Technology 1> First, we will explain related technology 1 for adjusting the height of the stage 12. Figures 6A and 6B are diagrams illustrating related technology 1. Details of related technology 1 are described, for example, in the above-mentioned Patent Document 1.

[0038] As shown in Figure 6A, consider the case where the beam is irradiated onto the surface of a sample S placed on the stage 12. The cross point CP of the ion beam IB and electron beam EB is located at a position ΔZ higher than the surface of the sample S. The height ΔZ is the distance between the surface of the sample S and the cross point CP, and the displacement ΔX is the distance that the irradiation position of the ion beam IB and the irradiation position of the electron beam EB are shifted on the surface of the sample S.

[0039] In the case shown in Figure 6A, the height ΔZ and displacement ΔX can be determined as follows. The displacement ΔX can be calculated using two secondary electron images obtained by the ion beam IB and electron beam EB, respectively, which are displayed on a display device 21 or the like. The displayed secondary electron images are the observation images shown in Figures 4A and 4B above. The height ΔZ can also be expressed by equation (1) ΔZ = ΔXx・Tanθ.

[0040] By moving the stage 12 in the Z direction by the calculated height ΔZ distance, the cross point CP can be positioned on the surface of the sample S, as shown in Figure 6B.

[0041] <Related Technology 2> Next, we will describe related technology 2 for adjusting the height of the stage 12. Figure 7 is a diagram illustrating related technology 2. Details of related technology 2 are described, for example, in the above-mentioned Patent Document 2. In the following explanation of Figure 7, the rotation of the stage 12 along the T-axis is referred to as tilt.

[0042] As shown in Figure 7, a displacement L occurs in the Y-axis direction. On the surface S0 of the sample S before tilting, the irradiation position of the electron beam EB shifts to V1 due to the displacement L. The Y-coordinate of the irradiation position P1 before tilting becomes Y1, which is a shift of the displacement L from Y0. The Y-coordinate of the irradiation position P1 after tilting becomes Yθ1.

[0043] To explain these positional relationships in more detail, on the surface S0 of the sample S before tilting, the irradiation position of the electron beam EB is shifted to V1 due to the displacement L, and the Y coordinate of the irradiation position P1 can be expressed by equation (2): Y1 = Y0 + L.

[0044] Next, the irradiation position P1 on the surface S0t tilted by an angle θ also tilts by an angle θ, so the Y-axis component of the displacement L is L × Cosθ. Therefore, the Y-coordinate of the irradiation position P1 after tilting can be expressed by equation (3): Yθ1 = Yθ0 + ​​L × Cosθ.

[0045] Furthermore, the amount of movement ΔY in the Y-axis direction of the irradiation position P1 can be expressed by equation (4): ΔY = Y0 - Yθ0 ≈ Zs × sinθ.

[0046] Here, by adding equations (4) and (2) to equation (3), we can express it by equation (5): Yθ1 = (Y0 - Zs × sinθ) + L × Cosθ = Y1 - L - Zs × sinθ + L × Cosθ = Y1 - Zs × sinθ + (cosθ - 1) × L

[0047] In equation (5), Y1, sinθ, and cosθ are known, while Zs and L are unknown. Therefore, by obtaining the Yθ1 values ​​for each surface tilted at two different tilt values ​​(θ) for the same irradiation position P1, two equations of (5) can be obtained. This makes it possible to calculate the unknown Zs and L. In this way, the height required to adjust the stage 12 to the cross point CP can be calculated.

[0048] In related technology 2, the T-axis is rotated twice, and the unknown height Zs and displacement L are calculated by applying equation (5) described above to the tilted stage resulting from each rotation.

[0049] <Issues that cannot be solved by related technologies> This section explains technical issues that cannot be solved by related technologies 1 and 2. Figures 8 to 11 are diagrams illustrating technical issues that cannot be solved by related technologies.

[0050] Figure 8 shows an example of the charged particle beam apparatus 10 in an ideal configuration. In the ideal state shown in Figure 8, the cross point CP and the rotation center C of the T axis coincide. By moving the stage 12 in the Z direction by ΔZ or ΔZs calculated by related technology 1 or related technology 2 from the height where the object of observation OT is located, the object of observation OT on the surface 12f0 of the sample S reaches a state where it coincides with the eucentric height, i.e., the cross point CP. In the following explanation, the object will be described as the object of observation OT, but the object may also be the area to be processed.

[0051] On the other hand, in the actual state shown in Figure 9, the cross point CP is offset from the rotation center C of the T-axis. Hereafter, this offset will be referred to as beam offset BO. Beam offset BO is caused by mounting errors of stage 12, errors when moving stage 12, or bending of the ion beam IB and electron beam EB from the beam axis. In a real charged particle beam apparatus, it is difficult to completely eliminate beam offset BO.

[0052] With a beam offset BO in place, ΔZ or ΔZs calculated by related technology 1 or related technology 2 is the height at which the X-axis of stage 12 intersects with the rotation center C of the T-axis when the rotation of the T-axis is 0 degrees. If the object of observation OT can be moved to this height, then when the tilt angle of the T-axis is 0 degrees, the object of observation OT will be located at the cross point CP.

[0053] Figure 10 shows the state after adjusting the height of the stage 12 by ΔZ or ΔZs from the actual state shown in Figure 9. When the rotation of the T-axis is 0 degrees, the observation target OT coincides with the cross point CP. In this state, when observing with the focused ion beam irradiation optical system 14 and the electron beam irradiation optical system 15, the charged particle beam apparatus 10 can acquire observation images of the same observation target OT from different angles.

[0054] On the other hand, Figure 11 shows the state where the T-axis is tilted so as to be directly facing the electron beam EB. The object to be observed OT is located at a beam offset BO from the rotation center C of the T-axis. Therefore, when the T-axis is tilted by an angle θ, the object to be observed OT moves in a circular arc with a radius equal to the distance of the beam offset BO. After tilting, the object to be observed OT is located at a position away from the cross point CP where the ion beam IB of the focused ion beam irradiation optical system 14 and the electron beam EB of the electron beam irradiation optical system 15 intersect. As a result, the object to be observed OT may be outside the imaging field of view of the focused ion beam irradiation optical system 14 or the electron beam irradiation optical system 15. In such cases, low-magnification observation is necessary to keep the object to be observed OT within the imaging field of view of the focused ion beam irradiation optical system 14 and the electron beam irradiation optical system 15. Setting the magnification of the captured image to a low level may reduce the accuracy of the captured image, making it difficult to see.

[0055] In the above Related Art 1 and Related Art 2, the method for correcting the user-centric height is appropriate when observing the observation target OT with the T-axis at 0 degrees. However, when observing the observation target OT with the T-axis rotated and the stage 12 inclined, a problem of visual field escape occurs. Furthermore, in Related Art 2, when performing T-axis rotation, it is necessary to tilt the stage twice to calculate the unknown height Zs and deviation L.

[0056] <First Embodiment> In the first embodiment, the computer system 22 calculates the user-centric height (the height at which the observation target OT is corrected to the cross point CP) in two ways: when the rotation angle of the T-axis is 0 (horizontal state) and when it is inclined (tilted state). FIG. 12 is a flowchart showing an example of the process of matching the cross point CP and the observation target OT executed by the computer system 22. FIGS. 13 and 14 are diagrams for explaining the process of matching the cross point CP and the observation target OT.

[0057] The computer system 22 calculates the first movement amount at T-axis 0 degrees (ST110). The first movement amount is the amount by which the stage 12 is moved in the Z direction to move the observation target OT of the sample S to the cross point CP. In other words, the first movement amount is the user-centric height.

[0058] FIG. 13 is a diagram for explaining the mechanism for calculating the first movement amount. The computer system 22 generates an observation image (first observation image) obtained from the irradiation result produced by irradiating the observation target OT with the ion beam IB facing the stage 12 at T-axis 0 degrees and an observation image (second observation image) obtained from the irradiation result produced by irradiating the observation target OT with the electron beam EB, and calculates the deviation L in the Y-axis direction based on these generated observation images. Here, the irradiation results are secondary electrons, reflected electrons, X-rays, etc. Next, the computer system 22 calculates the user-centric height using this deviation L. Specifically, the computer system 22 calculates the user-centric height by Z = Y ＳＥＭ / tanθ. The method for calculating the first movement amount at T-axis 0 degrees is the same as that of Related Art 1 described above.

[0059] Next, the computer system 22 moves the stage 12 (ST120). The computer system 22 controls the Z-direction drive unit 30 to move the stage 12 in the Z-direction according to the first amount of movement calculated in step ST110. As a result, at T-axis 0 degrees, the position of the observation target OT of the sample S placed on the stage 12 coincides with the position of the cross point CP.

[0060] In this way, after moving the stage 12, the charged particle beam apparatus 10 can acquire an observation image of the target OT at T-axis 0 degrees by performing observation image of the target OT with the focused ion beam irradiation optical system 14 and imaging of the target OT with the electron beam irradiation optical system 15.

[0061] Next, the computer system 22 rotates the T-axis by θ degrees (ST130). In this embodiment, the computer system 22 controls the T-axis rotation drive unit 35 to tilt the surface 12f0 of the stage 12 by θ degrees. Here, the angle θ is the angle at which the electron beam EB of the electron beam irradiation optical system 15 is aligned with the upper surface of the stage 12. The angle θ can be stored in advance within the computer system 22. As a result, the surface of the observation target OT of the sample S placed on the stage 12 is also tilted by an angle θ.

[0062] At this point, the position of the observation target OT, which was aligned with the cross point CP, shifts. To realign the shifted position of the observation target OT with the position of the cross point CP, it is necessary to move the stage 12 in two directions: the Z direction and the Y direction. Moving only in the Z direction is not enough to align the cross point CP with the position of the observation target OT.

[0063] Next, the computer system 22 calculates a second amount of movement in the T-axis θ degree (ST140). The second amount of movement is the amount of movement of the stage 12 to return the position of the observation target OT, which has shifted from the cross point CP due to the tilting of the stage 12, back to the cross point CP. The second amount of movement includes the amount of movement of the stage 12 in the Y direction and the amount of movement in the Z direction.

[0064] Figure 14 is a diagram illustrating the mechanism for calculating the second displacement. The computer system 22 calculates the displacement L in the Y direction and the displacement in the Z direction based on the observation image (third observation image) obtained from the irradiation result produced when the ion beam IB irradiates the observation target OT at T-axis θ degrees, and the observation image (fourth observation image) obtained from the irradiation result produced when the electron beam EB facing the stage 12 irradiates the observation target OT. Here, the irradiation result is secondary electrons, backscattered electrons, X-rays, etc., as explained with reference to Figure 13.

[0065] First, the computer system 22 calculates the amount of displacement in the Y direction. For the Y direction, the computer system 22 calculates the amount of displacement Y between the field of view, i.e., the center CE of the observation image and the observation target OT, in the observation image (fourth observation image) observed by the electron beam irradiation optical system 15. ＳＥＭ This can be determined by calculating [the formula].

[0066] Next, the computer system 22 calculates the amount of displacement in the Z direction. For the Z direction, the computer system 22 calculates the amount of displacement Y between the center of the observation image (fourth observation image) CE and the observation target OT in the observation image taken by the electron beam irradiation optical system 15. ＳＥＭ And the amount of displacement Y between the center CI and the observation target OT in the observation image (third observation image) taken by the focused ion beam irradiation optical system 14. ＦＩＢ And it can be determined from the angle θ, which is the inclination angle of stage 12. The formula used for this calculation is Z = (Y ＳＥＭ +Y ＦＩＢ ) / tanθ.

[0067] After calculating the second amount of movement, the computer system 22 moves the stage 12 (ST150). The computer system 22 moves the stage 12 by controlling, for example, the Y-direction drive unit 31, according to the Y-direction calculated in step ST140. ＳＥＭMove it by only Z in the Y direction. After this, the computer system 22 controls the Z-direction drive unit 30 to move the stage 12 in the Z direction by Z by the amount calculated in step ST140. This makes it possible to bring the position of the observation target OT, which had shifted from the cross point CP due to the rotation of the T axis by θ degrees, back into alignment with the cross point CP.

[0068] The amount of displacement Y of the electron beam EB when the T-axis is 0 degrees as described above. ＳＥＭ , Y when the T-axis is θ degrees ＳＥＭ +Y ＦＩＢ These values ​​are calculated by the computer system 22 from observation images taken by the focused ion beam irradiation optical system 14 and the electron beam irradiation optical system 15, respectively. In other words, the computer system 22 can calculate the amount of movement in the Z and Y directions (second amount of movement) required to move the observation target OT to the cross point CP by using observation images taken from two different angles of the observation target OT with respect to the stage 12 located at two different tilt angles (T-axis 0 degrees and θ degrees). This makes it possible for the computer system 22 to keep the observation target OT at the cross point CP even when the T-axis is tilted.

[0069] In this way, after moving the stage 12, the charged particle beam apparatus 10 can acquire observation images of the same observation target OT at T-axis θ degrees by observing the observation image of the observation target OT with the focused ion beam irradiation optical system 14 and imaging the observation target OT with the electron beam irradiation optical system 15.

[0070] Furthermore, in the related technology 2 described above, after moving the stage to the eucentric height, the stage is tilted twice, and the amount of stage movement is calculated using the observation images acquired at each tilt. However, in this embodiment, by tilting the stage 12 from 0 degrees on the T-axis to θ degrees by 1 degree, the eucentric height at 0 degrees on the T-axis, the eucentric height at θ degrees on the T-axis, and the amount of movement in the Y direction can be calculated. Therefore, the load on the computer system 22 can be reduced.

[0071] <First Modification> Next, the first modification will be described. In the first modification, the computer system 22 is configured to calculate the beam offset BO.

[0072] Figure 15 is a diagram illustrating the process for calculating the offset amount of the beam offset BO. The offset amount of the beam offset BO is L0, and d is the distance from the eucentric height calculated at 0 degrees T-axis until the ion beam IB is irradiated onto the observation target OT by the focused ion beam irradiation optical system 14 at θ degrees T-axis.

[0073] In this case, the offset amount L0 can be expressed by equation (6) L0 = d / tanθ.

[0074] Also, d is Y ＳＥＭ +Y ＦＩＢ Using this, d = (Y ＳＥＭ +Y ＦＩＢ ) / sinθ This can be expressed by equation (7).

[0075] Therefore, the offset amount L0 of the beam offset BO is L0 = (Y ＳＥＭ +Y ＦＩＢ It can be expressed by equation (8) as ) / sinθ / tanθ.

[0076] As previously described, the beam offset BO can occur due to mounting errors of the stage 12, errors when moving the stage 12, or the degree of curvature of the charged particle beam (ion beam IB, electron beam EB) from the beam axis. Therefore, by performing mechanical adjustments to the charged particle beam apparatus 10 and checking the offset amount L0 of the beam offset BO each time an adjustment is made, the operator can bring the offset amount L0 as close to 0 as possible. In this way, the operator can adjust the charged particle beam apparatus 10 to an ideal apparatus in which the offset amount L0 of the beam offset BO approaches 0.

[0077] Furthermore, by calculating the offset amount L0, the computer system 22 can calculate a second movement amount to return the object being observed OT to the cross point CP, even at any inclination angle. Figure 16 is a diagram illustrating the process of calculating the second movement amount to return the object being observed OT to the cross point CP.

[0078] When the offset amount of the beam offset BO is L0 and the tilt angle of the T-axis is θ1, the amount of movement in the Z direction Zθ1 and the amount of movement in the Y direction Yθ1 to return the object of observation OT to the cross point CP can be expressed using L0 and θ1 as follows: Zθ1 = L0 × sinθ Equation (9) Yθ1 = L0 × sinθ × tanθ - L0(1 / sinθ1 - 1) Equation (10)

[0079] As a result, the computer system 22 can move the object of observation OT to the cross point CP even when the angle of the T-axis is not directly aligned with the irradiation direction of the electron beam EB of the electron beam irradiation optical system 15. Therefore, according to the technique of this first modification, the tilt state of the stage 12 can be applied even if the stage 12 is not directly aligned with the irradiation direction of the electron beam EB, as long as the stage 12 faces the electron beam irradiation optical system 15, which is the light source of the electron beam EB.

[0080] <Second Modification> Regarding the X direction, it is not possible to correct using the relational formula as described above. However, the computer system 22 may calculate the amount of movement by storing the amount of deviation when the T-axis is at 0 degrees and when the T-axis is rotated, and interpolating the amount of deviation between them.

[0081] The above describes the case where the object of observation OT is moved to the cross point CP in the YZ plane, but this second modification describes the movement of the object of observation OT in the X direction. Figures 17A and 17B show an example of an observation image at 0 degrees on the T axis. Figure 17A is the observation image V1 by the electron beam irradiation optical system 15. ＳＥＭ As an example, Figure 17B shows the observation image V1 obtained by the focused ion beam irradiation optical system 14. ＦＩＢAn example is shown. Figures 18A and 18B show an example of an observation image at T-axis θ degrees. Figure 18A is an observation image V2 obtained by the electron beam irradiation optical system 15. ＳＥＭ As an example, Figure 18B shows the observation image V2 obtained by the focused ion beam irradiation optical system 14. ＦＩＢ An example is shown. Figures 17B and 18A are observation images of the OT being observed, viewed from directly above, while Figures 17A and 18B are observation images of the OT being observed, viewed from an oblique angle.

[0082] If the stage 12 can be tilted by ideal T-axis rotation, no image displacement in the X direction will occur when the stage 12 is tilted. However, in reality, due to the influence of the mounting position of the stage 12, weight balance, and the meshing of the gear 38, the observed object OT may move in the X direction when the stage 12 is rotated on the T-axis. For example, in Figures 17A and 17B, the center R1 of the observed image and the observed object OT coincide, but in Figures 18A and 18B, the center R1 of the observed image and the observed object OT are separated by distances D1 and D2.

[0083] In this second modification, the computer system 22 calculates the amount of movement in the axial direction of the T-axis from the amount of displacement between the center of the observation image by the electron beam irradiation optical system 15 and the observation target OT in the observation image in the axial direction of the T-axis. For example, the computer system 22 calculates the amount of displacement D1X in the X direction from the observation image of the electron beam irradiation optical system 15 when the T-axis is θ degrees. ＳＥＭ and D2X ＦＩＢ The process of calculating these displacement amounts may be included in the process of calculating the second displacement amount (ST140) described above. For example, the computer system 22 calculates the X component D1X of the distance D1 shown in Figure 18A. ＳＥＭ , and the X component D2X of the distance D2 shown in Figure 18B ＦＩＢ The system calculates the displacement X in the X direction from these values. The computer system 22 then controls the X-direction drive unit 33 to move the stage 12 in the X direction by the calculated displacement X. This makes it possible for the charged particle beam apparatus 10 to move the object of observation OT to the cross point CP in the X direction as well.

[0084] <Second Embodiment> When processing a sample S using the focused ion beam irradiation optical system 14 and observing the sample S using the electron beam irradiation optical system 15 by using the technology described in the first embodiment, the computer system 22 can move the object to be observed OT to the cross point CP each time it moves to the coordinates of the object to be observed. However, if there are multiple objects to be observed OT, calculating the position each time they move will place a load on the computer system 22, the cumulative calculation time will increase, and the efficiency of work such as processing and observation may decrease.

[0085] Therefore, the computer system 22 pre-calculates the eucentric height when the T-axis is at 0 degrees, and the amount of movement in the X, Y, and Z directions (mapping information) when the stage 12 is tilted, for each observation position (movement point) of the observation target OT, at predetermined planar coordinates of the sample S placed on the stage 12, and stores the calculated mapping information in a table or the like. The table can be stored, for example, in a memory unit (not shown) of the computer system 22.

[0086] Figure 19 shows an example of a table (mapping information management unit) 200 that stores mapping information.

[0087] As shown in Figure 19, the table 200 stores the XY coordinates for each moving point that is the object of observation, the eucentric height at 0 degrees T-axis of the moving point, and the displacement amounts ΔX, ΔY, and ΔZ, which indicate the deviation of each XYZ coordinate when the T-axis is rotated from the eucentric height. When the system moves to a predetermined moving point, the computer system 22 extracts two planar coordinates from the table 200 in order of proximity to the XY planar coordinates of the moving point, and uses interpolation and extrapolation to calculate the eucentric height at 0 degrees T-axis of the moving point (first displacement amount) and the displacement amount required when the T-axis is θ (second displacement amount). This makes it possible for the computer system 22 to estimate the eucentric height at 0 degrees T-axis and the displacement amount required when the T-axis is θ.

[0088] By storing mapping information in the table 200 in this way, the charged particle beam apparatus 10 can perform operations such as processing and observation at multiple locations on the sample S placed on the stage 12 without reducing work efficiency.

[0089] Furthermore, the computer system 22 can display the mapping information stored in table 200 on display device 21 in response to the user's input device 23. Figure 20 shows an example of mapping information display 21A.

[0090] Figure 20 shows the distribution as viewed from the X direction. D1 to D5 indicate the magnitude of the displacement, and as shown in bar 21A1, the relationship is D1 > D2 > D3 > D4 > D5. Distribution diagram 21A2 shows the relationship between the displacement ΔY and displacement ΔZ as viewed from the X direction when the T-axis is tilted. Note that the difference in displacement may be represented by different colors instead of text. What information from the mapping information is displayed and how it is displayed can be arbitrarily set. By making the mapping information visible, the operator can visually confirm the state of the stage 12's positional displacement when the T-axis rotates.

[0091] <Modified Example> The table 200 described in the second embodiment can also store the offset amount of the beam offset BO mentioned above.

[0092] Figure 21 shows an example of a table (mapping information management unit) 210 that stores mapping information with added offset amounts. As shown in Figure 21, in table 210, the offset amount of beam offset BO is added to the table 200 described in Figure 19. In other words, the table 220 shown in Figure 21 contains an offset amount for each observation target OT that indicates the amount of deviation when the ion beam IB is irradiated onto the observation target OT.

[0093] The computer system 22 can use the offset amount and the current T-axis rotation angle θ1 described above to calculate the amount of movement required to move the object of observation OT to the cross point CP, regardless of whether the tilt of the stage 12 due to the T-axis rotation is directly aligned with the irradiation direction of the electron beam EB of the electron beam irradiation optical system 15. As a result, when the stage 12 is tilted at a T-axis angle θ with respect to an arbitrary XY plane, the computer system 22 can move the object of observation OT to the cross point CP.

[0094] <Method for creating the table> Next, the method for creating the above table 200 will be explained. A semiconductor wafer may be used as the sample S. In the case of a sample S that has a periodic pattern, such as a semiconductor wafer, the computer system 22 performs the following process to acquire the observation images (1) to (4) at the location where a specific pattern is formed, that is, at the observation target OT.

[0095] (1) At 0 degrees T-axis, an observation image is acquired by the focused ion beam irradiation optical system 14, which views the observation target OT from directly above. (2) At 0 degrees T-axis, an observation image is acquired by the electron beam irradiation optical system 15, which views the observation target OT from an oblique angle. (3) At θ degrees T-axis, an observation image is acquired by the focused ion beam irradiation optical system 14, which views the observation target OT from an oblique angle. (4) At θ degrees T-axis, an observation image is acquired by the electron beam irradiation optical system 15, which views the observation target OT from directly above.

[0096] By acquiring four observation images as described above, the computer system 22 can calculate the first amount of movement (eucentric height) at 0 degrees T-axis and the second amount of movement required for the observation target OT to return to the cross point CP at θ degrees T-axis.

[0097] The computer system 22 can create a table 200 by performing the calculations of the four types of observation images acquired and the first and second displacement amounts at specified coordinates or dies within the semiconductor wafer.

[0098] Furthermore, in order to calculate the first and second amounts of movement, the computer system 22 may use pattern matching or AI-based image recognition. This allows the computer system 22 to perform the calculations automatically and at high speed. When using pattern matching, it is necessary to register a pattern matching reference in advance, and when using AI-based image recognition, it is necessary to register multiple of the above four images as a learning model in advance for the computer system 22 to perform the processing. For this reason, the operator stores the reference or the above four images in the storage unit (not shown) of the computer system 22 in advance, and then has the computer system 22 perform the above processing.

[0099] Furthermore, if the sample S is not a semiconductor wafer and does not have a specific pattern, the computer system 22 marks the sample S at 0 degrees T-axis using the focused ion beam irradiation optical system 14, and after marking, acquires the observation images (1) to (4) above, including the marking. As a result, even for a sample S without a specific pattern, the computer system 22 can calculate the first and second displacement amounts from the acquired observation images using the marking as a guide. This makes it possible for the computer system 22 to create a table 200 using the coordinate position of the marking for a sample S without a specific pattern.

[0100] <Third Embodiment> Next, we will describe the case in which the table 200 is applied to samples S of different thicknesses. The mapping information stored in the table 200 can be applied directly to samples S of the same thickness. That is, by moving the stage 12 to the height stored in the table 200, the observation target OT will be positioned at the cross point CP. On the other hand, if the mapping information stored in the table 200 is applied directly to samples S of different thicknesses, the observation target OT will be shifted from the cross point CP. For this reason, the computer system 22 corrects the mapping information of the table 200, as will be explained below.

[0101] For example, if a sample S with a thickness difference of Z is placed on the stage 12, when the object of observation OT, which is located at the center of the field of view in the focused ion beam irradiation optical system 14, is observed, the object of observation OT will not be at the center in the observation image of the electron beam irradiation optical system 15, and from the perspective of the observation image, Y ＳＥＭ The object of observation OT is observed at a position offset from the center. At this time, the thickness Z of the thin sample S is Y, as in Figure 13 above. ＳＥＭ This can be expressed as / tanθ. Therefore, the computer system 22 can determine the difference Z between the thickness of sample S when table 200 was created and a sample S with a different thickness. Accordingly, the computer system 22 can add the difference Z to table 200 and create table 220 for samples S with different thicknesses. Table 220 includes the amount of movement in the Z direction corresponding to the difference in thickness for each observed object OT in order to compensate for the different thicknesses.

[0102] Figure 22 shows an example of a table 220 that stores mapping information with added movement in the Z direction. As shown in Figure 22, in table 220, a difference Z is added to the field of movement Z at 0 degrees T-axis. By using table 220 with the added difference Z, the computer system 22 can apply table 200, which was previously created using samples S of different thicknesses, to samples S of different thicknesses, in this embodiment, to thin samples S. As a result, the charged particle beam apparatus 10 can use table 200, which was previously created using samples S of different thicknesses, simply by calculating the thickness of the sample S, thereby improving processing efficiency.

[0103] <Modification> Next, a modification of the third embodiment will be described. In the third embodiment, the computer system 22 calculates the displacement from the observation image of the electron beam irradiation optical system 15 when the object to be observed OT is positioned at the center of the field of view of the focused ion beam irradiation optical system 14, and calculates the difference Z in the thickness of the sample S. However, depending on the type of sample S, it may be desirable to avoid observing the focused ion beam irradiation optical system 14. This is because the surface of the sample S is etched by the irradiation of the ion beam IB of the focused ion beam irradiation optical system 14. This modification will describe a method to avoid such a situation.

[0104] Figure 23 shows an example of the stage movement mechanism 13 of this modified example. Compared to the stage movement mechanism 13 shown in Figure 2, the stage movement mechanism 13 shown in Figure 23 has an optical microscope OM added to it. The optical microscope OM is installed at an offset position (Xoff, Yoff) in the XY plane, which is an offset distance from the position where the focused ion beam irradiation optical system 14 is installed (illustration omitted). The optical microscope OM, positioned in such a location, irradiates light in a certain direction to the XY plane, and in this modified example, it is possible to observe within the field of view formed in the XY plane (hereinafter referred to as the "OM field of view"). The optical microscope OM is connected to a computer system 22, although this is not shown.

[0105] The computer system 22 moves the object to be observed OT into the field of view of the optical microscope OM, identifies the object to be observed OT, and moves the object to be observed OT to the center of the OM field of view. The distance between the center of the OM field of view and the center of the field of view of the focused ion beam irradiation optical system 14 is the same offset amount as the offset position (Xoff, Yoff) described above. Therefore, by controlling the Y-direction drive unit 31 and the X-direction drive unit 33, the computer system 22 can move the stage 12 by (Xoff, Yoff) from the center of the OM field of view in the XY plane, thereby moving the object to be observed OT to the center of the field of view of the focused ion beam irradiation optical system 14 without observation by the focused ion beam irradiation optical system 14. Then, the computer system 22 can calculate the difference Z in the thickness of the sample S by calculating the displacement using the observation image from the electron beam irradiation optical system 15.

[0106] <Method for positioning the object to be observed> Below, we will explain the method for positioning the object to be observed OT using the focused ion beam irradiation optical system 14 and the electron beam irradiation optical system 15 used in the description of each embodiment above. Figures 24 to 27 are diagrams illustrating the method for positioning the object to be observed.

[0107] The focused ion beam irradiation optical system 14 can obtain an observation image of the field of view by irradiating it with an ion beam IB, but in the process, as described above, the surface of the sample S is etched. When the object to be observed OT is on the outermost surface of the sample S, it is desirable to avoid observation with the ion beam IB as much as possible. In particular, when the sample S is a semiconductor sample, the object to be observed may be on the outermost surface. Normally, the computer system 22 moves the stage 12 near the object to be observed OT with the T-axis at 0 degrees, that is, facing the focused ion beam irradiation optical system 14, acquires an observation image with the focused ion beam irradiation optical system 14, and determines the position to be observed and processed by pattern matching or AI-based image recognition. However, if it is desired to avoid observation of the outermost surface by the focused ion beam irradiation optical system 14, a different approach from this position determination method is required.

[0108] Specifically, the computer system 22 determines the position as follows (1) to (4). Processing (1) The computer system 22 rotates the T-axis so that it faces the electron beam irradiation optical system 15. As a result, the stage 12 is tilted so that it faces the electron beam irradiation optical system 15. The computer system 22 uses the observation image from the electron beam irradiation optical system 15 to perform pattern matching or AI-based image recognition and moves the stage 12 to a position where the object to be observed OT can be observed and processed. Figure 24 shows the state in which the object to be observed OT is located at the cross point CP (CPx, CPy) when the stage 12 is tilted, for example, by the method described in the first embodiment.

[0109] (2) Processing With the T-axis still tilted, the computer system 22 does not scan the object under observation OT with the focused ion beam irradiation optical system 14, but instead performs marking processing with the focused ion beam irradiation optical system 14 right next to the object under observation OT. Since observation is not performed by the focused ion beam irradiation optical system 14, the object under observation OT is not irradiated with the ion beam IB. Figure 25 shows the marking M formed at position (Mx, My). In this case, since the object under observation OT is moved to be located at the cross point CP, it is possible to prevent the focused ion beam irradiation optical system 14 from processing at an unintended position. If the object under observation OT is not located at the cross point CP, it is possible that the focused ion beam irradiation optical system 14 will process at a position shifted vertically. Furthermore, the focus of the ion beam IB will also be shifted, which may result in blurred observation images or poor surface processing shapes. Processing (2) can avoid such situations.

[0110] After the marking process by the focused ion beam irradiation optical system 14 is completed, the computer system 22 recognizes the positions of the observation target OT and the markings by pattern matching of the observation image by the electron beam irradiation optical system 15 or by AI image recognition. Next, the computer system 22 calculates the distance D11 between the observation target OT and the matching. Because the observation target OT is located at the cross point CP, there is no field of view shift in the observation image by the electron beam irradiation optical system 15. Therefore, the computer system 22 can acquire an observation image with high magnification by the electron beam irradiation optical system 15, and the error in the measured distance D11 can be reduced.

[0111] (3) The processing computer system 22 protects the observation target OT with electron beam deposition. Here, electron beam deposition refers to the deposition of a metal or carbon film on the surface around the processing area to prevent etching by the ion beam IB when processing the sample with the focused ion beam irradiation optical system 14. Deposition gas is introduced into the sample chamber 11 from the gas supply unit 17, and film deposition is performed using the reaction with the ion beam IB from the focused ion beam irradiation optical system 14. Figure 26 shows the deposited protective region PT. With the formation of the protective region PT, even if the observation target OT is scanned by the focused ion beam irradiation optical system 14 thereafter, the protective region PT of the observation target OT of the sample S will not be damaged.

[0112] The processing computer system 22 in (4) rotates back to 0 degrees on the T axis and observes the target OT with the focused ion beam irradiation optical system 14. In this case, the position of the stage 12 is adjusted so that the target OT is located at the cross point CP. The computer system 22 uses the observation image from the focused ion beam irradiation optical system 14 to perform pattern matching or AI image recognition to identify the position of the marking M. The distance D11 from the position of the marking M to the target OT has already been calculated in the processing in (2) above. For this reason, the computer system 22 has the focused ion beam irradiation optical system 14 process a position in the XY plane that is offset by an amount from the position where the marking was detected. Figure 27 shows the offset distance D11.

[0113] In step (4), the charged particle beam apparatus 10 can process the object OT with the focused ion beam irradiation optical system 14 at a highly precisely positioned location while avoiding damage to the object OT due to scanning by the focused ion beam irradiation optical system 14. To enable this, it is important that the object OT is located at the cross point CP at both T-axis 0 degrees and T-axis θ degrees, and this disclosure provides, for example, an example of a method for achieving this, as described in the first embodiment.

[0114] Furthermore, the following method can also be considered to calculate the amount of movement required to return the object of observation OT to the cross point CP when the T-axis is θ, that is, when the stage 12 is tilted. The method disclosed above calculates the amount of displacement of the object of observation OT when tilted and calculates the amount of movement of the stage 12 required to move the object of observation OT to the cross point CP. However, it is also possible for the computer system 22 to correct the calculated displacement using the beam shift function of the ion beam IB of the focused ion beam irradiation optical system 14 and the beam shift function of the electron beam EB of the electron beam irradiation optical system 15. The beam shift function is a function that shifts the beam within the field of view.

[0115] Furthermore, in the charged particle beam apparatus 10, it is also possible to use a combination of methods, such as using the method described in related technology 2 for calculating the eucentric height at T-axis 0 degrees, and using the method disclosed herein for calculating the amount of displacement when the stage 12 is tilted at T-axis θ degrees.

[0116] Although embodiments of this disclosure have been described in detail above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the gist of the invention. Each embodiment allows for the addition, deletion, and replacement of components, except for essential components. Unless otherwise specified, each component may be singular or plural. Combinations of each embodiment and its variations are also possible. Each of the aforementioned configurations, functions, and processing units may be implemented in part or in whole by hardware, such as by designing an integrated circuit, or by software, such as by a processor interpreting and executing a program. Data and information such as programs, tables, and files that realize each function can be stored in a recording device such as memory, a hard disk, or an SSD, or on a recording medium such as an IC card, an SD card, or a DVD.

[0117] 10...Charged particle beam apparatus, 11...Sample chamber, 12...Stage, 13...Stage movement mechanism, 14...Focused ion beam irradiation optical system, 15...Electron beam irradiation optical system, 16...Detector, 17...Gas supply unit, 21...Display device, 22...Computer system, 23...Input device, 30...Z-direction drive unit, 31...Y-direction drive unit, 33...X-direction drive unit, RA...Arrow (stage rotation direction), TA...Arrow (T-axis rotation direction), CE...Center of image captured by electron beam irradiation optical system, CI...Center of image captured by focused ion beam irradiation optical system, OT...Observation target

Claims

1. The apparatus comprises: a stage on which a sample with a defined observation area is placed; a stage moving mechanism capable of changing the position of the stage in the height direction and in the direction intersecting the height direction, the rotation of the stage, and the tilt of the stage; a first optical system for irradiating the sample with a first beam; a second optical system for irradiating the sample with a second beam at a different angle from the first beam; and a computer system for controlling the operation of the stage moving mechanism, the first optical system, and the second optical system, and acquiring an observation image from the irradiation result produced when the first beam and the second beam irradiate the sample, wherein the computer system, when the stage is in a horizontal position, calculates a first amount of movement to move the stage so that the observation area is located at the position where the first beam and the second beam intersect, based on a first observation image acquired from the irradiation result produced when the first beam facing the stage irradiates the observation area and a second observation image acquired from the irradiation result produced when the second beam irradiates the observation area, and changes the position of the stage according to the first amount of movement. Charged particle beam apparatus, wherein, at the changed position, the stage moving mechanism is controlled to change the inclination of the stage from the horizontal state to an inclined state in which the stage faces the light source of the second beam; when the stage is in the inclined state, a second amount of movement is calculated to move the stage so that the observation area moves to a position where the first beam and the second beam intersect, based on a third observation image obtained from the irradiation result obtained when the first beam irradiates the observation area and a fourth observation image obtained from the irradiation result obtained when the second beam irradiates the observation area; and the position of the stage is changed according to the second amount of movement.

2. A charged particle beam apparatus according to claim 1, wherein the second amount of movement includes the amount of movement in the intersecting direction, and the computer system calculates the amount of movement in the intersecting direction from the amount of displacement between the center of the fourth observation image and the object to be observed included in the fourth observation image in the intersecting direction.

3. A charged particle beam apparatus according to claim 2, wherein the second amount of movement further includes the amount of movement in the height direction, and the computer system calculates the amount of movement in the height direction from the amount of displacement between the center of the fourth observation image in the cross direction and the object to be observed included in the fourth observation image, the amount of displacement between the center of the third observation image in the height direction and the object to be observed included in the third observation image, and the inclination angle of the stage.

4. A charged particle beam apparatus according to claim 1, wherein when the inclination of the stage is changed from the horizontal state to the inclined state, the inclined state is a state in which the stage is directly facing the second beam.

5. A charged particle beam apparatus according to claim 1, wherein the stage moving mechanism has a T-axis perpendicular to the plane formed by the first beam and the second beam, the inclination of the stage changes from the horizontal state to the inclined state by rotating the T-axis, and the direction of intersection is perpendicular to the axial direction of the T-axis.

6. A charged particle beam apparatus according to claim 5, wherein the second amount of movement further includes an amount of movement in the axial direction of the T-axis, and the computer system calculates the amount of movement in the axial direction of the T-axis from the amount of displacement between the center of the fourth observation image and the object of observation in the fourth observation image in the axial direction of the T-axis.

7. A charged particle beam apparatus according to claim 1, wherein a single sample includes a plurality of observation regions, and the computer system includes a mapping information management unit that calculates a first displacement amount and a second displacement amount for each observation region, and manages the calculated first displacement amount and second displacement amount for each observation region as mapping information.

8. A charged particle beam apparatus according to claim 7, wherein the mapping information management unit includes an offset amount indicating the amount of displacement when the first beam is irradiated onto the observation area for each observation area.

9. A charged particle beam apparatus according to claim 7, wherein the mapping information management unit includes, for each observation area, the amount of movement in the height direction corresponding to the difference in thickness, depending on the sample having a different thickness from the sample.

10. A charged particle beam apparatus according to claim 9, further comprising an input device and a display device, wherein, in response to instructions from the input device, the display device displays mapping information managed by the mapping information management unit.

11. A charged particle beam apparatus according to claim 1, wherein the first beam is an ion beam and the second beam is an electron beam.

12. A method for positioning a charged particle beam apparatus, the charged particle beam apparatus comprising: a stage on which a sample with a defined observation area is placed; a stage moving mechanism capable of changing the position of the stage in the height direction and in an intersecting direction with the height direction, the rotation of the stage, and the tilt of the stage; a first optical system for irradiating the sample with a first beam; a second optical system for irradiating the sample with a second beam at a different angle from the first beam; and a computer system for controlling the stage moving mechanism, the first optical system, and the second optical system, and for acquiring observation images from the irradiation results produced when the first beam and the second beam are irradiated onto the sample, the positioning method comprising: a step of calculating a first amount of movement for moving the stage so that the observation area is located at the position where the first beam and the second beam intersect, based on a first observation image acquired from the irradiation results produced when the first beam facing the stage irradiates the observation area and a second observation image acquired from the irradiation results produced when the second beam irradiates the observation area, when the stage is in a horizontal state; A method for positioning a charged particle beam apparatus, comprising: changing the position of the stage in accordance with the first amount of movement; controlling the stage movement mechanism at the changed position to change the inclination of the stage from a horizontal state to an inclined state in which the stage faces the light source of the second beam; calculating a second amount of movement for moving the stage so that the observation area is moved to a position where the first beam and the second beam intersect, based on a third observation image obtained from an irradiated object produced when the first beam is irradiated onto the observation area and a fourth observation image obtained from an irradiated object produced when the second beam is irradiated onto the observation area, when the stage is in the inclined state; and changing the position of the stage in accordance with the second amount of movement.

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