Charged particle beam device and control method thereof

Abstract

To provide a charged particle beam device and a control method that are capable of automatically correcting the tilt of a sample.SOLUTION: A charged particle beam device includes a holding unit that can hold a sample having a reference surface and change an angle of the sample with respect to at least a first direction. A first irradiation unit irradiates the sample with first charged particles from a second direction and can process the sample so as to have a first surface intersecting the reference surface and a second surface spaced apart from the first surface in the first direction by a first distance. A second irradiation unit irradiates the first surface and the second surface with second charged particles from the first direction. A detection unit irradiates the first surface and the second surface with the second charged particles and detects third charged particles from the first surface and the second surface. An image processing unit generates a first image of the first surface and a second image of the second surface based on the detected third charged particles. A control and calculation unit calculates an inclination angle of the reference surface with respect to the first direction based on a first shift amount of the reference surface in the first image and the second image and the first distance, and controls the holding unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present embodiment relates to a charged particle beam device and a control method thereof. [Background technology]

[0002] As semiconductor device structures become taller, the aspect ratio of the processed structures becomes larger. When observing a sample with a high aspect ratio using a FIB (Focused Ion Beam)-SEM (Scanning Electron Microscope) device, the sample may be tilted from the desired position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-134750 Summary of the Invention [Problem to be solved by the invention]

[0004] A charged particle beam device capable of automatically correcting the tilt of a sample and a control method thereof are provided. [Means for solving the problem]

[0005] The charged particle beam device according to the present embodiment includes a holder capable of holding a sample having a reference surface and capable of changing at least an angle of the sample with respect to a first direction. The first irradiation unit irradiates the sample with first charged particles from a second direction and can process the sample so as to have a first surface intersecting the reference surface and a second surface separated from the first surface by a first distance in the first direction from the first surface. The second irradiation unit irradiates the first surface and the second surface with second charged particles from the first direction. The detection unit irradiates the first surface and the second surface with the second charged particles and detects third charged particles from the first surface and the second surface. The image processing unit generates a first image of the first surface and a second image of the second surface based on the detected third charged particles. The control and calculation unit calculates an inclination angle of the reference surface with respect to the first direction based on a first deviation amount of the reference surface in the first image and the second image and the first distance, and controls the holder. [Brief description of the drawings]

[0006] [Figure 1] 1 is a diagram showing an example of the configuration of a charged particle beam system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing how the FIB irradiation unit and the EB irradiation unit irradiate a sample with an ion beam and an electron beam. [Figure 3A] FIG. [Figure 3B] FIG. 3B is a cross-sectional view taken along line BB in FIG. 3A. [Figure 3C] 3B is a cross-sectional view taken along line CC in FIG. 3A. [Figure 4A] FIG. 4 is a plan view showing how sample 5 is processed. [Figure 4B] FIG. 4B is a cross-sectional view taken along line BB in FIG. 4A. [Figure 4C] 4B is a cross-sectional view taken along line CC in FIG. 4A. [Figure 5A] FIG. 4 is a plan view showing how sample 5 is processed. [Figure 5B] 5B is a cross-sectional view taken along line BB in FIG. 5A. [Figure 5C] 5B is a cross-sectional view taken along line CC in FIG. 5A. [Figure 6] 13 is a diagram showing the relationship between the distance Δdt, the deviation amount Δds, and the tilt angle θ. [Figure 7]FIG. 4 is a flow chart showing an example of a control method for the charged particle beam device according to the first embodiment. [Figure 8A] 8A to 8C are diagrams showing how a sample is processed according to a second embodiment. [Figure 8B] 8B is a cross-sectional view taken along line BB in FIG. 8A. [Figure 8C] 8B is a cross-sectional view taken along line CC in FIG. 8A. [Figure 9A] 8A to 8C are diagrams showing how a sample is processed according to a second embodiment. [Figure 9B] 9B is a cross-sectional view taken along line BB in FIG. 9A. [Figure 9C] 9B is a cross-sectional view taken along line CC in FIG. 9A. [Figure 10] FIG. 11 is a flow chart showing an example of a control method for the charged particle beam device according to the second embodiment. [Figure 11A] 13A to 13C are views showing how a sample is processed according to a third embodiment. [Figure 11B] 11B is a cross-sectional view taken along line BB in FIG. 11A. [Figure 11C] 11B is a cross-sectional view taken along line CC in FIG. 11A. [Figure 12A] 13A to 13C are views showing how a sample is processed according to a third embodiment. [Figure 12B] 12B is a cross-sectional view taken along line BB in FIG. 12A. [Figure 12C] 12B is a cross-sectional view taken along line CC in FIG. 12A. [Figure 13A] 13A to 13C are views showing how a sample is processed according to a third embodiment. [Figure 13B] 13B is a cross-sectional view taken along line BB in FIG. 13A. [Figure 13C] 13B is a cross-sectional view taken along line CC in FIG. 13A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment. The drawings are schematic or conceptual. In the specification and the drawings, the same elements are given the same reference numerals.

[0008] (First embodiment) 1 is a diagram showing an example of the configuration of a charged particle beam device according to the first embodiment. The charged particle beam device 100 is an FIB-SEM device that irradiates an electron beam onto a sample 5 processed by an FIB, detects secondary electrons generated from the sample 5, and obtains an image of the sample 5.

[0009] The charged particle beam device 100 includes a chamber 1, an FIB irradiation unit 2, an EB (Electron Beam) irradiation unit 3, a secondary electron detector 4a, a transmitted electron detector 4b, a holding unit 6, a driving unit 7, an image processing unit 8, a control and calculation unit 9, an input unit 10, and a display unit 11.

[0010] The chamber 1 accommodates a sample 5. The inside of the chamber 1 is depressurized by a vacuum pump (not shown).

[0011] The FIB irradiation unit 2 irradiates the sample 5 with an ion beam (FIB) from the X direction to process the sample 5. The FIB irradiation unit 2 can also deposit a protective film on the surface of the sample 5 by irradiating the sample 5 with an ion beam.

[0012] The EB irradiation unit 3 irradiates the sample 5 with an electron beam (EB) from the Z direction. The Z direction and the X direction are approximately perpendicular to each other. That is, the irradiation direction of the ion beam of the FIB irradiation unit 2 and the irradiation direction of the electron beam of the EB irradiation unit 3 are perpendicular to each other. Therefore, the charged particle beam device 100 is an orthogonal type charged particle beam device.

[0013] The secondary electron detector 4a detects secondary electrons generated from the sample 5 by irradiating the sample 5 with an electron beam.

[0014] The transmission electron detector 4 b detects the transmission electrons that have transmitted through the sample 5 .

[0015] The holder 6 holds the sample 5. The holder 6 is driven by a driver 7 to change the angle of the sample 5 with respect to the X direction or the Z direction.

[0016] The driving unit 7 moves or rotates the holding unit 6 under the control of the control and calculation unit 9. The driving unit 7 changes the incident angle of the ion beam or electron beam with respect to the sample 5, for example, by moving or rotating the holding unit 6.

[0017] The image processor 8 generates an image of the sample 5 based on the secondary electrons detected by the secondary electron detector 4a. The image processor 8 also monitors the amount of transmitted electrons detected by the transmitted electron detector 4b.

[0018] The control and calculation unit 9 processes the image of the sample 5 generated in the image processing unit 8, and controls the drive unit 7 to correct the tilt of the sample 5. The control and calculation unit 9 controls the FIB irradiation unit 2 and the EB irradiation unit 3, etc. The control and calculation unit 9 causes the image of the sample 5 to be displayed on the display unit 11.

[0019] The input unit 10 is an interface that allows various information to be input from the outside, and transmits the input information to the control and calculation unit 9. The input unit 10 may be, for example, a keyboard.

[0020] The display unit 11 may be a display that displays images and the like from the control and calculation unit 9. The input unit 10 and the display unit 11 may be integrated into a touch panel display.

[0021] FIG. 2 is a diagram showing how the FIB irradiation unit 2 and the EB irradiation unit 3 irradiate the sample 5 with an ion beam and an electron beam.

[0022] The FIB irradiation unit 2 irradiates the sample 5 with an ion beam in the X direction to cut the sample 5. This allows the sample 5 to be processed to have a first face F1 and a second face F2 that are substantially parallel to the XY plane. The second face F2 is a face that is a distance Δdt away from the first face F1 in the -Z direction. The first and second faces F1 and F2 are planes that are substantially parallel to each other.

[0023] The EB irradiation unit 3 irradiates the electron beam from the Z direction onto the first and second faces F1, F2 of the sample 5. The secondary electron detector 4a detects secondary electrons generated when the electron beam is irradiated onto the sample 5. The image processing unit 8 generates images of each of the first and second faces F1, F2 of the sample 5 based on the amount (intensity) of secondary electrons detected by the secondary electron detector 4a.

[0024] 3A to 5C are diagrams showing how sample 5 is processed. Figs. 3A, 4A, and 5A are plan views of sample 5. Figs. 3B, 4B, and 5B are cross-sectional views taken along line BB in Figs. 3A, 4A, and 5A, respectively. Figs. 3C, 4C, and 5C are cross-sectional views taken along line CC in Figs. 3A, 4A, and 5A, respectively.

[0025] As shown in Figures 3A to 3C, the sample 5 includes a stack 20 configured by alternately stacking a plurality of electrode films and a plurality of insulating films along the Z direction, for example. The stack 20 constitutes a memory cell array. The memory cell array is a three-dimensional memory cell array in which memory cells are arranged three-dimensionally. SUB is, for example, a semiconductor substrate such as a silicon substrate.

[0026] In the stack 20, a pillar CL is provided in each of the memory holes MH. The pillar CL extends in the stacking direction (X direction) of the stack 20 so as to penetrate the stack 20. A description of the internal structure of the pillar CL is omitted. In this embodiment, the pillar CL is one stage. However, since the pillar CL has a high aspect ratio, it may be formed in two stages in the X direction.

[0027] Further, a slit ST is provided in the stack 20. The slit ST extends in the Z direction and penetrates the stack 20 in the stacking direction (X direction) of the stack 20. An insulating film such as a silicon oxide film is filled in the slit ST, and the insulating film is configured in a plate shape. The slit ST electrically separates the electrode films of the stack 20. Alternatively, the inner wall of the slit ST may be covered with an insulating film such as a silicon oxide film, and a conductive material may be further embedded inside the insulating film. In this case, the conductive material also functions as a source wiring that reaches a source layer below the stack 20.

[0028] Referring to FIG. 3B, it can be seen that the sample 5 is inclined at an inclination angle θ with respect to the Z direction. The inclination is the inclination of the sample 5 from the irradiation direction (Z direction) of the electron beam from the EB irradiation unit 3. The inclination of the sample 5 is the inclination of the interface (reference plane) B between the material layers stacked in the sample 5. For example, the interface B is the interface between any two layers included in the sample 5. Specifically, for example, the interface B may be the interface between two insulating films of different compositions formed on the stack 20, or the interface between a conductive film (for example, a metal film) and an insulating film. The interface B may also be the interface between the surface of a semiconductor substrate and an interlayer insulating film thereon, or the interface between the stack 20 and an interlayer insulating film deposited thereon. Such an inclination of the sample 5 occurs depending on the manner in which the holding unit 6 holds the sample 5. In other words, the sample 5 may be inclined when the holding unit 6 holds the sample 5. In order to automatically correct the tilt of the sample 5 to a target value (for example, to bring the tilt angle θ closer to zero), the charged particle beam device 100 processes the sample 5 and performs calculations as follows.

[0029] As shown in FIGS. 4A to 4C, the FIB irradiation unit 2 irradiates a part of the sample 5 with an ion beam to process the sample 5. The FIB irradiation unit 2 cuts the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam at least in the Y direction. Alternatively, the FIB irradiation unit 2 may cut the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam in the Y and Z directions. As a result, as shown in FIG. 4B, the sample 5 is processed to have a cutting surface (first surface F1) that is approximately parallel to the XY plane.

[0030] Next, as shown in FIG. 5A to FIG. 5C, the FIB irradiation unit 2 irradiates a part of the sample 5 with an ion beam to process the sample 5. The FIB irradiation unit 2 irradiates the sample 5 with an ion beam from the X direction and cuts a part of the sample 5 in the Y direction by moving the irradiated ion beam at least in the Y direction. Alternatively, the FIB irradiation unit 2 may cut a part of the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam in the Y direction and the Z direction. At this time, as shown in FIG. 5A, the ion beam cuts a part of the first surface F1 of the sample 5 and processes the sample 5 to have a stepped second surface F2. As a result, as shown in FIG. 5B, the sample 5 is processed to further have a second surface F2 that is approximately parallel to the XY plane. The second surface F2 is a surface of the sample 5 that is approximately parallel to the first surface F1 and is a distance Δdt away from the first surface F1 in the Z direction.

[0031] Here, as shown in Fig. 5B, the sample 5 is inclined at an inclination angle θ with respect to the Z direction. Therefore, as shown in Fig. 5C, a first image S1 of the first surface F1 and a second image S2 of the second surface F2 obtained by irradiating an electron beam from the Z direction by the EB irradiation unit 3 are shifted in the X direction (height direction). That is, in a plan view from the Z direction, the sample 5 is inclined with respect to the Z direction, and the first surface F1 and the second surface F2 are at different depths, so that the positions of the structures of the sample 5 on the first surface F1 and the positions of the structures of the sample 5 on the second surface F2 are shifted in the X direction (height direction).

[0032] If the tilt angle θ is zero, the first image of the first surface F1 and the second image of the second surface F2 in FIG. 5C will not be shifted in the X direction, and the positions of the structures of the sample 5 on the first surface F1 and the positions (heights) of the structures of the sample 5 on the second surface F2 should be approximately the same in the X direction.

[0033] However, since the sample 5 is inclined at an inclination angle θ with respect to the Z direction, a shift occurs in the X direction (height direction) between the first image S1 of the first surface F1 and the second image S2 of the second surface F2. The interface B1 between the two interlayer insulating films of different compositions formed on the stack 20 in the first image S1 and the interface B2 between the two interlayer insulating films of different compositions formed on the stack 20 in the second image S2 are shifted in the X direction by a shift amount Δds. The interfaces B1 and B2 may be, for example, interfaces between any two layers included in the sample 5. Specifically, for example, the interfaces B1 and B2 may be interfaces between two insulating films of different compositions formed on the stack 20, or interfaces between a conductive film (for example, a metal film) and an insulating film. The interfaces B1 and B2 may be interfaces between the surface of a semiconductor substrate and an interlayer insulating film thereon, or interfaces between the stack 20 and an interlayer insulating film deposited thereon.

[0034] The control and calculation unit 9 according to this embodiment calculates the inclination angle θ of the interfaces B1, B2 with respect to the Z direction using the principle of triangulation based on the distance Δdt between the first surface F1 and the second surface F2 and the amount of deviation Δds in the X direction between the interface B1 of the first surface F1 and the interface B2 of the second surface F2. The distance Δdt may be a value input from the outside via the input unit 10. Alternatively, the image processing unit 8 and the control and calculation unit 9 may measure the distance Δdt using a SIM (Scanning Ion Microscope) image obtained when an ion beam is irradiated from the FIB irradiation unit 2.

[0035] 6 is a diagram showing the relationship between the distance Δdt, the deviation Δds, and the inclination angle θ. In this case, the control calculation unit 9 calculates the inclination angle θ of the interfaces B1 and B2 with respect to the Z direction using Equation 1.

[0036] θ=tan -1 (Δds / Δdt) (Equation 1) The control and calculation unit 9 drives the drive unit 7 so as to bring the tilt angle θ closer to a target value (for example, zero), and feedback controls the tilt of the holder 6. This makes it possible to automatically correct the tilt of the sample 5.

[0037] In this way, the charged particle beam device 100 according to this embodiment can automatically correct the tilt of the sample 5. By correcting the tilt of the sample 5, the FIB irradiation unit 2 can cut the sample 5 with the ion beam in a direction approximately perpendicular to the interfaces B1 and B2. As a result, the accurate structure of the sample 5 can be known from the image obtained by the EB irradiation unit 3 irradiating it with an electron beam.

[0038] When acquiring the first image S1 of the first surface F1 and the second image S2 of the second surface F2 of the sample 5, the EB irradiator 3 may irradiate the electron beam with the same focus. However, if the distance Δdt between the first surface F1 and the second surface F2 is large, the focus of the first surface F1 and the second surface F2 exceeds the range of the focal depth of the electron beam, so that if the focus of the electron beam is the same, the first image S1 or the second image S2 may be out of focus. In this case, the detection accuracy of the deviation amount Δds is deteriorated.

[0039] Therefore, when acquiring a first image S1 of the first surface F1 of the sample 5, the EB irradiation unit 3 focuses on the first surface F1 and irradiates the electron beam. When acquiring a second image S2 of the second surface F2, the EB irradiation unit 3 focuses on the second surface F2 and irradiates the electron beam. The secondary electron detector 4a focuses the electron beam on each of the first surface F1 and the second surface F2 and detects them individually. Note that when focusing the electron beam on each of the first surface F1 and the second surface F2 and detecting them, the position of the sample 5 and the optical conditions of the electron beam are not changed. The image processing unit 8 generates a composite image by combining the first image S1 and the second image S2 obtained individually by changing the focus of the electron beam in this way. The first image S1 and the second image S2 are combined by matching the outer peripheries of those images. As a result, for example, an image shown in FIG. 5C is obtained. The composite image is suppressed from being out of focus. Therefore, the image processor 8 can accurately measure the amount of deviation Δds between the interfaces B1 and B2 based on the composite image.

[0040] FIG. 7 is a flow chart showing an example of a control method for the charged particle beam device according to the first embodiment.

[0041] First, the sample 5 is attached to the holder 6 and placed in the chamber 1 .

[0042] The FIB irradiation unit 2 irradiates the sample 5 with an ion beam and processes the sample 5 into a stepped shape so as to form a first face F1 and a second face F2 (S10). The FIB irradiation unit 2 cuts the sample 5 by irradiating the sample 5 with an ion beam from the X direction and moving the irradiated ion beam at least in the Y direction. Alternatively, the FIB irradiation unit 2 may cut the sample 5 by irradiating the sample 5 with an ion beam from the X direction and moving the irradiated ion beam in the Y direction and the Z direction. When the first face F1 is formed, the sample 5 only needs to be cut so that the first face F1 is flat with respect to the XY plane, so the amount of engraving of the sample 5 in the Z direction may be small. On the other hand, when the second face F2 is formed, it is necessary to increase the distance Δdt between the first face F1 and the second face F2 to a certain extent in order to increase the amount of deviation Δds. For this reason, it is preferable that the amount of engraving (Δdt) of the second face F2 in the Z direction relative to the first face F1 is larger than the amount of engraving of the sample 5 in the Z direction at the first face F1.

[0043] Next, the first and second faces F1, F2 are thinly scraped by an ion beam to smooth the first and second faces F1, F2, which are the imaging surfaces of the sample 5 (S20).

[0044] Next, the image processing unit 8 generates images of the first and second surfaces F1, F2, and recognizes the interfaces B1 and B2 of the sample 5 (S30). Furthermore, the image processing unit 8 may enhance the interfaces B1 and B2.

[0045] Next, the control and calculation unit 9 controls the drive unit 7 to rotate the holder 6 so that the interfaces B1 and B2 become approximately parallel to the Y direction (S40).

[0046] Next, the EB irradiation unit 3 irradiates the first and second faces F1, F2 of the sample 5 with the electron beam, and the detection unit 4 detects secondary electrons from the sample 5. The image processing unit 8 generates first and second images S1, S2 from the detected secondary electrons (S50). The EB irradiation unit 3 may simultaneously irradiate the first and second faces F1, F2 of the sample 5 with the electron beam, and the detection unit 4 may detect the secondary electrons from the sample 5 at once. In this case, the image processing unit 8 can simultaneously obtain the first and second images S1, S2 by irradiating the electron beam once. On the other hand, the focus of the electron beam may be changed to irradiate the first and second faces F1, F2 with the electron beam, respectively. In this case, the image processing unit 8 generates the first and second images S1, S2 from the secondary electrons detected individually by the detection unit 4, and then combines them to obtain a composite image. The electron beam from the EB irradiation unit 3 is irradiated with a focus adapted to the first and second faces F1, F2, respectively. This allows the detection unit 4 and the image processing unit 8 to capture the first and second images S1 and S2 at different times. Therefore, the first and second images S1 and S2 are images focused on the first and second planes F1 and F2, respectively. That is, the composite image is an image focused on the first and second planes F1 and F2.

[0047] Furthermore, the image processing unit 8 enhances the interfaces B1, B2 by image processing of the first and second images S1, S2 or the composite image (S60).

[0048] Next, the control and calculation unit 9 calculates the amount of deviation Δds between the interface B1 and the interface B2 from the first and second images S1, S2 or the composite image (S70).

[0049] The control and calculation unit 9 compares the amount of deviation Δds with a predetermined threshold value (S80). If the amount of deviation Δds is equal to or greater than the predetermined threshold value (NO in S80), the control and calculation unit 9 calculates Equation 1 from the distance Δdt between the first surface F1 and the second surface F2 and the amount of deviation Δds, which have been input in advance, to obtain the tilt angle θ of the sample 5 (S90).

[0050] Next, the control and calculation unit 9 feedback controls the drive unit 7 and the holder 6 to bring the tilt angle θ closer to zero, and corrects the tilt of the sample 5 with respect to the Z direction (S100).

[0051] The control and calculation unit 9 repeats steps S50 to S100 after correcting the tilt of the sample 5. That is, the control and calculation unit 9 repeats the calculation of the tilt angle θ and the control of the holding unit 6 until the deviation amount Δds becomes smaller than a predetermined threshold value.

[0052] When the deviation amount Δds is smaller than the predetermined threshold value (YES in S80), the control calculation unit 9 ends the adjustment of the tilt angle θ.

[0053] In this way, the charged particle beam device 100 according to this embodiment can automatically correct the inclination of the sample 5 with respect to the Z direction based on the deviation amount Δds of the interfaces B1 and B2 in the images S1 and S2 of the first surface F1 and the second surface F2 of the sample 5. By correcting the inclination of the sample 5 with respect to the Z direction, the FIB irradiation unit 2 can cut the sample 5 with the ion beam in a direction approximately perpendicular to the interfaces B1 and B2. As a result, the accurate structure of the sample 5 can be known from the image obtained by irradiating the EB irradiation unit 3 with an electron beam.

[0054] If the distance Δdt between the first and second surfaces F1 and F2 is small, the EB irradiation unit 3 can focus the electron beam almost on both the first and second surfaces F1 and F2 at the same time. In this case, the detection unit 4 and the image processing unit 8 can capture the first and second surfaces F1 and F2 at the same time and obtain the first and second images S1 and S2 at the same time. However, if the distance Δdt between the first and second surfaces F1 and F2 is too small, the deviation amount Δds of the interfaces B1 and B2 due to the tilt angle θ of the sample 5 becomes small. In this case, the calculation accuracy of the tilt angle θ in the control calculation unit 9 becomes lower than when the distance Δdt between the first and second surfaces F1 and F2 is large.

[0055] On the other hand, if the distance Δdt between the first and second surfaces F1, F2 is large, the deviation Δds of the interfaces B1, B2 becomes large. Therefore, the calculation accuracy of the tilt angle θ in the control calculation unit 9 becomes relatively high. However, it is difficult for the EB irradiation unit 3 to focus the electron beam on both the first and second surfaces F1, F2 at the same time. Therefore, in this case, the image processing unit 8 needs to generate a composite image by combining the first and second surfaces F1, F2 obtained by individually capturing the images. For example, the distance Δdt is preferably 1 μm to 100 μm.

[0056] Furthermore, when the sample 5 is removed from the first surface F1 to form the second surface F2, if the thickness in the Y direction of the sample 5 left in the region of the second surface F2 is too thin, the electron beam may pass through the sample 5. In this case, the number of secondary electrons detected by the detection unit 4 decreases. Therefore, it is preferable that the thickness in the Y direction of the sample 5 left in the region of the second surface F2 is at least as thick as not to allow the electron beam to pass through.

[0057] Second embodiment 8A to 9C are diagrams showing how sample 5 is processed according to the second embodiment. Fig. 8A and Fig. 9A are plan views of sample 5. Fig. 8B and Fig. 9B are cross-sectional views taken along line BB in Fig. 8A and Fig. 9A, respectively. Fig. 8C and Fig. 9C are cross-sectional views taken along line CC in Fig. 8A and Fig. 9A, respectively.

[0058] In the second embodiment, the sample 5 has a third surface F3 spaced apart in the Z direction from the first and second surfaces F1, F2. As in the first embodiment, the control and calculation unit 9 calculates a first tilt angle θ1 from Equation 1 based on a first shift amount Δds1 of the interfaces B1, B2 in the first image S1 and the second image S2 and a first distance Δdt1 from the first surface F1 to the second surface F2.

[0059] Furthermore, the control calculation unit 9 acquires a third image S3 of a third surface F3 separated in the Z direction from the first and second surfaces F1 and F2, and measures a second shift amount Δds2 of the interfaces B2 and B3 in the second image S2 and the third image S3. The control calculation unit 9 calculates a second tilt angle θ2 from Equation 1 based on the second shift amount Δds2 and a second distance Δdt2 from the second surface F2 to the third surface F3.

[0060] The control calculation unit 9 calculates an average value θa of the tilt angles θ1 and θ2. The control calculation unit 9 controls the drive unit 7 and the holding unit 6 so that the average value θa approaches zero.

[0061] The configuration of the second embodiment may be the same as that of the first embodiment.

[0062] According to the second embodiment, a plurality of steps are formed in the sample 5, and a plurality of first and second tilt angles θ1, θ2 are calculated using the first to third faces F1-F3 and the first to third images S1-S3 due to the respective steps. In this manner, the tilt angle of the sample 5 with respect to the Z direction is calculated by averaging the plurality of tilt angles θ1, θ2, so that the second embodiment can calculate the tilt angle with higher accuracy.

[0063] FIG. 10 is a flow chart showing an example of a control method for the charged particle beam device according to the second embodiment.

[0064] First, the sample 5 is attached to the holder 6 and placed in the chamber 1 .

[0065] The FIB irradiation unit 2 irradiates the sample 5 with an ion beam and processes the sample 5 into a stepped shape so as to form the first to third faces F1 to F3 (S11). The FIB irradiation unit 2 cuts the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam at least in the Y direction. Alternatively, the FIB irradiation unit 2 may cut the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam in the Y and Z directions. When the first face F1 is formed, the sample 5 only needs to be cut so that the first face F1 is flat with respect to the XY plane, so the amount of engraving in the Z direction of the sample 5 may be small. On the other hand, when the second and third faces F2 and F3 are formed, it is necessary to increase the distance Δdt1 between the first face F1 and the second face F2 and the distance Δdt2 between the second face F2 and the third face F3 to some extent in order to increase the deviation amounts Δds1 and Δds2. For this reason, it is preferable that the depth of engraving (Δdt1) of the second surface F2 in the Z direction relative to the first surface F1 is larger than the depth of engraving of the sample 5 in the Z direction. In addition, it is preferable that the depth of engraving (Δdt2) of the third surface F3 in the Z direction relative to the second surface F2 is larger than the depth of engraving of the sample 5 in the Z direction.

[0066] Next, the first to third faces F1 to F3 are thinly scraped by an ion beam to smooth the first to third faces F1 to F3, which are the imaging surfaces of the sample 5 (S21).

[0067] Next, the image processor 8 generates images of the first to third surfaces F1 to F3, and recognizes the interfaces B1 to B3 of the sample 5 shown in Fig. 9C (S31). Furthermore, the image processor 8 may emphasize the interfaces B1 to B3.

[0068] Next, the control and calculation unit 9 controls the drive unit 7 to rotate the holder 6 so that the interfaces B1 to B3 become approximately parallel to the Y direction (S40).

[0069] Next, the EB irradiation unit 3 irradiates the first to third faces F1 to F3 of the sample 5 with the electron beam, and the detection unit 4 detects secondary electrons from the sample 5. The image processing unit 8 generates the first to third images S1 to S3 from the detected secondary electrons (S51). The EB irradiation unit 3 may simultaneously irradiate the first to third faces F1 to F3 of the sample 5 with the electron beam, and the detection unit 4 may detect the secondary electrons from the sample 5 at once. In this case, the image processing unit 8 can simultaneously obtain the first to third images S1 to S3 by irradiating the electron beam once. On the other hand, the focus of the electron beam may be changed to irradiate the first to third faces F1 to F3 individually. In this case, the image processing unit 8 obtains a composite image by combining the first to third images S1 to S3 from the secondary electrons individually detected by the detection unit 4. The EB irradiation unit 3 adjusts the focus of the electron beam to the first to third faces F1 to F3, respectively. This allows the detection unit 4 and image processing unit 8 to capture the first to third images S1 to S3 at different timings. Therefore, the first to third images S1 to S3 are images focused on the first to third planes F1 to F3, respectively. That is, the composite image is an image focused on the first to third planes F1 to F3.

[0070] Furthermore, the image processing unit 8 enhances the interfaces B1 to B3 by image processing the first to third images S1 to S3 or the composite image (S61).

[0071] Next, the control and calculation unit 9 calculates the amount of deviation Δds1 between the interfaces B1 and B2 from the first to third images S1 to S3 or the composite image, and calculates the amount of deviation Δds2 between the interfaces B2 and B3 (S71).

[0072] Next, the control calculation unit 9 compares the deviation amounts Δds1 and Δds2 with a predetermined threshold value (S81). If either one of the deviation amounts Δds1 and Δds2 is equal to or greater than the predetermined threshold value (NO in S81), the control calculation unit 9 calculates the tilt angle θ1 of the sample 5 by calculating Equation 1 from the deviation amount Δds1 and the distance Δdt1 between the first surface F1 and the second surface F2, both of which have been input in advance. Furthermore, the control calculation unit 9 calculates the tilt angle θ2 of the sample 5 by calculating Equation 1 from the deviation amount Δds2 and the distance Δdt2 between the second surface F2 and the third surface F3, both of which have been input in advance (S91).

[0073] Next, the control calculation unit 9 calculates the average value θa of the tilt angles θ1 and θ2 (S95).

[0074] Next, the control and calculation unit 9 feedback-controls the drive unit 7 and the holder 6 to make the average value θa of the tilt angles θ1 and θ2 approach zero, thereby correcting the tilt of the sample 5 with respect to the Z direction (S101).

[0075] After correcting the inclination of the sample 5 with respect to the Z direction, the control and calculation unit 9 repeats steps S51 to S101. That is, the control and calculation unit 9 repeats the calculation of the average value θa and the control of the holding unit 6 until both of the deviation amounts Δds1 and Δds2 become smaller than predetermined threshold values.

[0076] When both of the deviation amounts Δds1 and Δds2 are smaller than the predetermined threshold value (YES in S81), the control calculation unit 9 ends the adjustment of the tilt angles θ1 and θ2.

[0077] In this way, the charged particle beam device 100 according to the second embodiment calculates a plurality of tilt angles θ1, θ2 based on the shift amount Δds1 of the interfaces B1, B2 and the shift amount Δds2 of the interfaces B2, B3 in the first to third images S1 to S3 of the first to third surfaces F1 to F3 of the sample 5. Then, the charged particle beam device 100 can automatically correct the tilt of the sample 5 with respect to the Z direction by using the average value θa of the plurality of tilt angles θ1, θ2. By correcting the tilt of the sample 5 with respect to the Z direction by the average value θa of the plurality of tilt angles θ1, θ2, the second embodiment can calculate the tilt angle with respect to the Z direction with higher accuracy.

[0078] Other operations of the second embodiment may be the same as those of the first embodiment, and therefore the second embodiment can achieve the same effects as the first embodiment.

[0079] The control calculation unit 9 may calculate the third tilt angle θ3 from Equation 1 based on the third shift amount Δds3 of the interfaces B1, B3 in the first image S1 and the third image S3, respectively, and the third distance Δdt3 (Δds3=Δds1+Δds2) from the first surface F1 to the third surface F3. The control calculation unit 9 may further use the tilt angle θ3 thus obtained to calculate the average value θa. In this case, for example, the average value θa may be any of the average of the tilt angles θ1, θ2, and θ3, the average of the tilt angles θ1 and θ3, or the average of the tilt angles θ2 and θ3.

[0080] (Modification) In the above embodiment, the interfaces B1 to B3 are interfaces between any two layers included in the sample 5. Specifically, for example, the interfaces B1 to B3 may be interfaces between two insulating films of different compositions formed on the laminate 20, or an interface between a conductive film (e.g., a metal film) and an insulating film. The interfaces B1 to B3 may also be interfaces between the substrate SUB and the laminate 20, or interfaces between the laminate 20 and an interlayer insulating film thereon. The interfaces B1 to B3 may also be interfaces between any electrode film in the laminate 20 and an insulating film.

[0081] Third embodiment 11A to 13C are diagrams showing how sample 5 is processed according to the third embodiment. Figs. 11A, 12A, and 13A are plan views of sample 5. Figs. 11B, 12B, and 13B are cross-sectional views taken along line BB in Figs. 11A, 12A, and 13A, respectively. Figs. 11C, 12C, and 13C are cross-sectional views taken along line CC in Figs. 11A, 12A, and 13A, respectively.

[0082] In the third embodiment, the sample 5 may include, for example, a bulk silicon substrate, a ceramic substrate, or a metal plate. In the case of a bulk substrate, since it does not have a laminated film, there is no interface that serves as a reference plane for the inclination of the sample 5 in the Z direction. In such a case, a protective film 30 may be formed on the sample 5, and an interface B4 between the protective film 30 and the sample 5 may be used as a reference plane. In other words, the protective film 30 may be deposited on a substrate SUB, which is a material to be processed, and an interface B4 between the protective film 30 and the substrate SUB may be used as a reference plane. The protective film 30 is laminated on the surface of the sample 5 as a pretreatment before the sample 5 is loaded on the charged particle beam device 100. At this time, the method of laminating the protective film 30 on the surface of the sample 5 may be thermal evaporation of carbon or sputtering evaporation of gold or platinum. In this case, the material of the protective film 30 is a carbon film or a metal film such as gold or platinum. The material of the protective film 30 may be any material different from the sample 5.

[0083] 11A to 11C, a protective film 30 is deposited on the surface of a substrate SUB of a sample 5. The protective film 30 may be, for example, a carbon film or a metal film such as gold or platinum.

[0084] As shown in FIG. 11B, an interface B4 between the substrate SUB and the protective film 30 is inclined at an inclination angle θ with respect to the Z direction.

[0085] As shown in FIGS. 12A to 12C, the FIB irradiation unit 2 irradiates a part of the sample 5 with an ion beam to process the sample 5. The FIB irradiation unit 2 cuts the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam at least in the Y direction. Alternatively, the FIB irradiation unit 2 may cut the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam in the Y and Z directions. As a result, as shown in FIG. 12B, the sample 5 is processed to have a cutting surface (first surface F1) that is approximately parallel to the XY plane.

[0086] Next, as shown in FIG. 13A to FIG. 13C, the FIB irradiation unit 2 irradiates a part of the sample 5 with an ion beam to process the sample 5. The FIB irradiation unit 2 cuts the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam at least in the Y direction. Alternatively, the FIB irradiation unit 2 may cut the sample 5 by irradiating the sample with an ion beam from the X direction and moving the irradiated ion beam in the Y direction and the Z direction. At this time, as shown in FIG. 13A, the ion beam cuts a part of the first surface F1 of the sample 5, and processes the sample 5 to have a stepped second surface F2. As a result, as shown in FIG. 13B, the sample 5 is processed to further have a second surface F2 approximately parallel to the XY plane.

[0087] Here, since the sample 5 is inclined at an inclination angle θ with respect to the Z direction, as shown in FIG. 13C, the first face F1 and the second face F2 are misaligned in the X direction (height direction). That is, the first image and the second image S1, S2 obtained by irradiating the first and second faces F1, F2 of the sample 5 with the electron beam from the EB irradiation unit 3 are also misaligned in the X direction (height direction). The interface B4 between the substrate SUB and the protective film 30 formed thereon in the first image S1 and the interface B5 between the substrate SUB and the protective film 30 formed thereon in the second image S2 are misaligned in the X direction by a misalignment amount Δds. That is, the interface B4 between the sample 5 and the material film formed thereon in the first image S1 and the interface B5 between the sample 5 and the material film formed thereon in the second image S2 are misaligned in the X direction by a misalignment amount Δds.

[0088] The control calculation unit 9 calculates the inclination angle θ of the interfaces B1, B2 with respect to the Z direction using the principle of triangulation based on the distance Δdt between the first surface F1 and the second surface F2 and the deviation amount Δds in the X direction between the interface B1 of the first surface F1 and the interface B2 of the second surface F2. The control calculation unit 9 may calculate the inclination angle θ using, for example, Equation 1 as in the first embodiment.

[0089] The configuration of the charged particle beam system 100 according to the third embodiment may be the same as that of the first embodiment. Moreover, the operation of the charged particle beam system 100 according to the third embodiment may be the same as that of the first embodiment.

[0090] The charged particle beam device 100 according to the third embodiment can automatically correct the tilt angle θ even for a bulk substrate that does not have an interface such as a laminated film. Moreover, the third embodiment can obtain the same effects as the first embodiment.

[0091] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0092] 100 Charged particle beam device 1. Chamber 2 FIB irradiation section 3 EB irradiation section 4a Secondary electron detector 4b Transmission electron detector 5. Sample 6 Holding part 7 Drive unit 8 Image Processing Section 9 Control and calculation section 10 Input section 11 Display section

Claims

1. A holder capable of holding a sample having a reference surface and capable of changing an angle of the sample with respect to at least a first direction; a first irradiation unit that irradiates a first charged particle from a second direction and processes the sample so as to have a first surface that intersects with the reference surface and a second surface that is a first distance away from the first surface in the first direction; a second irradiation unit that irradiates the first surface and the second surface with second charged particles from the first direction; a detection unit that irradiates the first surface and the second surface with the second charged particles and detects third charged particles from the first surface and the second surface; an image processing unit that generates a first image of the first surface and a second image of the second surface based on the detected third charged particles; a control and calculation unit that calculates an inclination angle of the reference plane with respect to the first direction based on a first shift amount of the reference plane in the first image and the second image and the first distance, and controls the holding unit.

2. the first direction and the second direction are substantially perpendicular to each other, When a first deviation amount of the reference surface between the first surface and the second surface is Δds and the first distance is Δdt, the control calculation unit calculates an inclination angle θ of the reference surface with respect to the first direction using Equation 1. θ = tan －１ (Δds / Δdt) (Equation 1) 2. The charged particle beam device of claim 1.

3. 2. The charged particle beam device according to claim 1, wherein the image processing unit generates a composite image by combining the first image and the second image obtained by focusing the second irradiation unit on each of the first surface and the second surface and detecting them individually, and measures a first deviation amount of the reference surface based on the composite image.

4. The charged particle beam device according to claim 1 , wherein the control and calculation unit repeats the calculation of the tilt angle and the control of the holder until the first deviation amount becomes smaller than a threshold value.

5. A protective film is provided on the sample, 2. The charged particle beam device according to claim 1, wherein the control and calculation unit uses an interface between the protective film and the sample as the reference surface.

6. The charged particle beam device of claim 1 , wherein the first surface and the second surface are substantially parallel.

7. a holder capable of holding a sample having a reference surface and capable of changing a relative angle of the sample with respect to at least a first direction; a first irradiation unit that irradiates first charged particles from a second direction and processes the sample so as to have a first surface that intersects with the reference surface, a second surface that is spaced a first distance from the first surface in the first direction, and a third surface that is spaced a second distance from the second surface in the first direction; a second irradiation unit that irradiates the first surface and the second surface with second charged particles from the first direction; a detection unit that irradiates the first surface, the second surface, and the third surface with the second charged particles and detects the third charged particles from the first surface, the second surface, and the third surface; an image processing unit that generates a first image of the first surface, a second image of the second surface, and a third image of the third surface based on the detected third charged particles; calculating a first tilt angle of the reference plane with respect to the first direction based on a first deviation amount of the reference plane in the first image and the second image and the first distance; calculating a second inclination angle of the reference plane with respect to the first direction based on a second deviation amount of the reference plane in the second image and the third image and the second distance; a control and calculation unit that calculates an average value of the first tilt angle and the second tilt angle and controls the holding unit.

8. A method for controlling a charged particle beam device comprising: a holder capable of holding a sample and capable of changing a relative angle of the sample with respect to at least a first direction; a first irradiation unit that irradiates the sample with first charged particles in a second direction to process the sample; a second irradiation unit that irradiates the sample with second charged particles in the first direction; a detection unit that irradiates the sample with the second charged particles and detects third charged particles from the sample; an image processing unit that generates an image of the sample based on the detected third charged particles; and a control and calculation unit that controls the holder, acquiring a first image of the third charged particles from a first surface of the sample; acquiring a second image of the third charged particles from a second surface of the sample that is a first distance away from the first surface in the first direction; calculating an inclination angle of the reference plane with respect to the first direction based on a first shift amount of a reference plane of the sample including the first image and the second image and the first distance; A method for controlling a charged particle beam device, comprising: controlling the holding unit.

Images