JP2011204367A - Sample stand for electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sample stand for an electron microscope allowing highly precise EBSD analysis.SOLUTION: This sample stand 31 for the electron microscope includes a pedestal 33 attached to a sample holder 9 attachable to a sample stage 5, a shaft 35 fixed perpendicular to the pedestal 33, a hollow member 37 formed with a hollow part 37a extended along an axial direction in a body inside, formed with at least one through-hole 41 on a body barrel part side face, inserted into the shaft 35 via the hollow part 37a, and rotatable along a circumferential direction of the shaft 35 under a condition inserted into the shaft 35, and a fixing member 39 inserted into the through hole 41 and for fixing a relative position of the hollow member 37 to the shaft 35, by supporting the shaft 35 and the hollow member 37. A sample 3 is attached onto an upper face of the hollow member 37.

Description

  The present invention relates to an electron microscope sample stage used in an electron microscope.

  Metallic materials and ceramic materials having a texture are determined to have basic properties such as mechanical properties depending on the size of the structure to be formed, the crystal orientation, the dislocations in the crystal, the state of grain boundaries, and the like. Therefore, it is very important to analyze the crystal information of the material, and the texture has been analyzed for a long time.

  In recent years, an electron beam backscattering pattern (hereinafter referred to as “EBSD”) method using a scanning electron microscope (hereinafter referred to as “SEM”) has been widely used. The EBSD method is intended to analyze the crystal orientation and crystal structure of the local region using the backscattering diffraction pattern (Electron Back-Scattering Diffraction Pattern) that is generated when a narrowly focused electron beam is incident on the sample surface in the SEM. (See Non-Patent Document 1).

  Since the position of the EBSD pattern is greatly changed by a slight inclination of the crystal, it is 0. Precise crystal orientation analysis of n ° is possible, and in order to perform highly accurate EBSD analysis, pretreatment of the sample and fixation of the sample during measurement are important. In the EBSD measurement, information in a range of a depth of several tens of nanometers from the sample surface is obtained, so that the processing strain generated during the pretreatment greatly affects the result. Therefore, in the EBSD measurement, preprocessing is performed with great care, such as electromechanical polishing after conventional mechanical polishing to remove the strained layer generated by mechanical polishing.

  In addition, the EBSD method is applied to an analysis in which a structural analysis captures a change in a structure that changes depending on an environment added in a manufacturing process of an actual product from the material itself. This is because an actual product contains various kinds of materials due to compounding of materials, and thus cannot be handled by a conventional pretreatment method. Therefore, recently, processing by a focused ion beam (hereinafter also referred to as “FIB”) processing apparatus using Ga ions has become common as a sample preparation method for an electron microscope.

  The focused ion beam processing (observation) apparatus is an apparatus that cuts a sample by a sputtering effect by focusing Ga ions and applying them to the sample. The processing using the focused ion beam processing apparatus has the characteristics that the material of the sample is not selected and the damage to the inside of the observation sample is less than other methods. Further, in processing using a focused ion beam processing apparatus, carbon or tungsten is deposited by FIB-CVD (Focused Ion Beam Chemical Vapor Deposition) by flowing a reactive gas together with a Ga ion beam into the atmosphere. Can be bonded or fixed. Therefore, the processing using the focused ion beam processing apparatus is, for example, as described in Patent Document 1, in combination with a working probe function, a sample piece that is an observation target including a desired specific portion from a sample (analysis sample) So-called microsampling (method) is possible, in which only the sample is extracted and fixed to the sample stage using deposition. As described above, the focused ion beam processing apparatus can deal with a composite sample, and can freely extract and fix the sample by microsampling.

  A sample extracted by microsampling is, for example, a sample mesh having a shape obtained by cutting a 3 mm diameter plate used in a transmission electron microscope (hereinafter referred to as “TEM”) into a semicircle. Fixed. This sample mesh is fixed by using a conductive paste so as to stand perpendicular to the SEM sample stage, or by using a conductive tape, whereby EBSD measurement is performed by SEM.

  By the way, in the EBSD measurement, for example, as shown in FIG. 9, in an electron microscope, an electron diffraction pattern (EBSD pattern) based on electrons scattered / diffracted in the sample 100 and back-scattered is efficiently sent to the detector 104. It is necessary to perform measurement with the measurement surface 102 of the sample 100 tilted by about 70 degrees with respect to the incident direction of the electron beam (incident electrons). Further, since it is necessary to position the measurement surface 102 in the plane where the measurement surface 102 is located without rotating, it is necessary to accurately position and fix the sample surface 106 perpendicular to the measurement surface 102. When the sample 100 is fixed to the sample table by paste or the like, the sample surface 106 cannot be accurately positioned. Therefore, it was difficult to analyze the sample by accurate EBSD.

Japanese Patent Laid-Open No. 11-108813

Osamu Umezawa “What SEM-EBSD Knows” Heat Treatment Vol. 41, No. 5

  The present invention has been proposed in view of such circumstances, and provides a sample stage for an electron microscope that can accurately analyze a sample by EBSD analysis in the crystal orientation analysis of the sample using the EBSD method by SEM. With the goal.

  That is, an electron microscope sample stage according to the present invention includes a pedestal attached to a sample holder that can be mounted on a sample stage of an electron microscope, an axis fixed perpendicularly to the pedestal, and an axial direction inside the main body. A hollow portion is formed, and at least one through hole is formed on the side surface of the main body body. The hollow portion is inserted into the shaft through the hollow portion, and the circumferential direction of the shaft is inserted into the shaft. A rotatable hollow member, and a fixing member that is inserted into the through-hole and supports the shaft and the hollow member, thereby fixing a relative position between the hollow member and the shaft, A sample is attached to the upper surface of the hollow member.

  In the electron microscope sample stage according to the present invention, the pedestal and the hollow member are formed so that the lower surface of the pedestal contacting the sample holder and the upper surface of the hollow member are parallel to each other. When the angle of the sample stage is controlled by the control unit, the angle of the measurement surface of the sample with respect to the incident direction of the electron beam is controlled via the sample holder and the electron microscope sample stage. And

  The sample is manufactured by a microsampling method using a FIB processing apparatus. The sample is attached to a sample mesh using a deposition film formed by FIB-CVD.

  The sample mesh is attached to the upper surface of the hollow member using a conductive paste.

  In the present invention, since the hollow member inserted in the axial direction can rotate in the circumferential direction of the shaft, the relative position between the hollow member and the shaft can be adjusted and fixed by the fixing member. Thereby, since the incident angle of the electron beam with respect to the measurement surface of a sample can be set correctly, highly accurate EBSD analysis can be performed.

It is a figure which shows typically the structural example of the electron microscope using the sample stand for electron microscopes concerning this Embodiment. (A) is a top view which shows the sample stage which mounts the sample stand for electron microscopes concerning this Embodiment, (B) is a sample stage which mounts the sample stand for electron microscopes concerning this Embodiment. It is a perspective view shown. (A) is an exploded perspective view schematically showing an electron microscope sample stage according to the present embodiment, and (B) is a perspective view schematically showing an electron microscope sample stage according to the present embodiment. It is. It is a top view which shows the state which installed the sample mesh which mounted the sample on the sample stand for electron microscopes concerning this Embodiment. It is a perspective view which shows typically the method of extracting a micro sample with a microsampling method. It is a perspective view which shows typically the state which fixed the micro sample extracted by the micro sampling method to the sample mesh. (A) is a figure which shows typically an example of the attachment method of a sample mesh, (B) is a side view which shows the sample stand for electron microscopes to which the sample mesh was fixed. It is a figure which shows the state which performs EBSD measurement using the sample stand for electron microscopes which concerns on this Embodiment. It is a figure which shows an EBSD measuring method typically.

Hereinafter, an example of a specific embodiment of an electron microscope sample stage to which the present invention is applied will be described in detail in the following order with reference to the drawings.
1. 1. Configuration example of electron microscope 2. Sample stage for electron microscope Preparation of sample and attachment of sample 3-1. Microsampling method 3-2. Attaching the sample to the sample mesh 3-3. 3. Attaching the sample mesh to the sample table Example

<1. Configuration example of electron microscope>
FIG. 1 is a diagram schematically showing a configuration example of an electron microscope equipped with an EBSD system in which the electron microscope sample stage (hereinafter also simply referred to as “sample stage”) according to the present embodiment is used.

  The electron microscope 1 includes a sample stage 5 that holds an electron microscope sample stage 31 to which the sample 3 is attached via a sample holder 9, an electron beam irradiation unit 7 that irradiates the sample 3 with an electron beam, and a reflection from the sample 3. And a CCD camera 11 as a detector for taking an electron diffraction image based on the electron beam. The electron microscope 1 also includes a stage control unit 13 that controls the movement or tilt angle of the sample stage 5, and a camera control unit 15 that controls the focus and the diaphragm of the CCD camera 11.

  The sample stage 5 includes, for example, a horizontal movement mechanism that can move in the two-dimensional direction of the x-axis and the y-axis, a height movement mechanism that can move in the z-axis direction, an inclination mechanism, and the like. The sample stage 5 is controlled in two-dimensional direction and inclination through a stage control unit 13 by a system control unit 17 constituted by, for example, a personal computer.

  The electron beam irradiation unit 7 generates an electron beam from the electron gun 19. The electron beam generated from the electron gun 19 is finely focused on the surface of the sample 3 by the focusing lens 21 and the objective lens 23, and scanned on the sample 3 by the scanning coil 25. The electron beam is back-scattered from the sample 3 by the electron beam irradiation, and an electron beam diffraction image based on the elastically scattered reflected electrons is taken by the CCD camera 11. An electron diffraction image signal photographed by the CCD camera 11 is sent to an analysis processing unit (not shown) via the camera control unit 15. As described above, the CCD camera 11 constitutes an imaging unit that captures a diffraction image.

<2. Sample table for electron microscope>
As shown in FIG. 2, the electron microscope sample stage 31 according to the present embodiment can be detachably attached to a sample stage mounting part 34 formed on the sample holder 9. For example, as shown in FIG. 3, the electron microscope sample stage 31 includes a pedestal 33, a shaft 35 attached to the pedestal 33, a hollow member 37, and a fixing member 39.

  The pedestal 33 is preferably formed of, for example, a plate-like material and has conductivity and no magnetism, for example, aluminum, from the viewpoint of performing EBSD measurement with the electron microscope 1.

  The shaft 35 is preferably formed of, for example, a columnar shape, and is made of a material having conductivity and no magnetism, for example, aluminum, like the pedestal 33. The shaft 35 is connected to the center of the upper surface 33a of the pedestal 33 and perpendicular to the pedestal 33, for example.

  The hollow member 37 is a cylindrical member in which a hollow portion 37 a extending in the axial direction inside the main body of the hollow member 37 is formed. The hollow member 37 is, for example, a cylindrical member having a concentric circular part. The hollow member 37 is preferably made of a material that has electrical conductivity and does not have magnetism, such as aluminum. When the hollow member 37 is inserted into the shaft 35 in the direction indicated by the arrow in FIG. 3A through the hollow portion 37a, the hollow member 37 is in contact with the shaft 35. As shown in FIG. 4, the hollow member 37 is rotatable in the circumferential direction of the shaft 35, that is, in the arrow direction shown in FIG. 4 while being inserted in the shaft 35.

  Further, as shown in FIG. 3A, a through hole 41 into which the fixing member 39 is inserted is provided in the main body body portion of the hollow member 37. The fixing member 39 is made of, for example, a screw. When the fixing member 39 is inserted into the through hole 41 as shown in FIG. 3B, the fixing member 39 supports the shaft 35 and the hollow member 37, thereby The relative position, that is, the angle between the hollow member 37 and the shaft 35 is fixed. In other words, in the electron microscope sample stage 31, when the fixing member 39 is inserted into the through hole 41 in a state where the hollow member 37 is inserted in the axial direction with respect to the shaft 35, the fixing member 39 is connected to the shaft 35. The hollow member 37 is supported and the position (angle) of the hollow member 37 with respect to the shaft 35 is fixed.

  As shown in FIGS. 1 to 3, the microscope sample stage 31 is formed so that the lower surface 33 b of the pedestal 33 in contact with the sample holder 9 and the upper surface 37 b of the hollow member 37 are parallel to each other. A member 37 is formed. More specifically, the lower surface 33b of the pedestal 33, the upper surface 33a of the pedestal 33 in contact with the lower surface 37c of the hollow member 37, the lower surface 37c of the hollow member 37, and the upper surface 37b of the hollow member are all parallel. A pedestal 33 and a hollow member 37 are formed.

  In the electron microscope 1 using such a microscope sample stage 31, when the angle of the sample stage 5 is controlled by the stage control unit 13, the electron beam passes through the sample holder 9 and the electron microscope sample stage 31. The angle of the measurement surface 3a of the sample 3 with respect to the incident direction is controlled. More specifically, in the electron microscope 1, when the angle of the sample stage 5 is controlled by the stage controller 13, the upper surface 5a of the sample stage 5 in contact with the sample holder 9 and the sample holder 9 parallel to the upper surface 5a Through the lower surface 9a, the upper surface 9b of the sample holder 9 in contact with the pedestal 33 and parallel to the pedestal 33, the angle between the incident direction of the electron beam and the measurement surface 3a of the sample 3 is controlled via the pedestal 33 and the hollow member 37. Is done.

  Therefore, in the electron microscope 1 using the electron microscope sample stage 31, the stage controller 13 controls the sample stage 5 to be tilted by about 70 degrees with respect to the incident direction of the electron beam, thereby measuring the sample 3. Since the surface 3a can be set in a state inclined about 70 degrees with respect to the incident direction of the electron beam, highly accurate EBSD analysis can be performed.

  Further, as shown in FIG. 4, the electron microscope sample stage 31 is rotatable in the circumferential direction of the shaft 35 with the hollow member 37 being inserted into the shaft 35, and is fixed to the hollow member 37 by the fixing member 39. The relative position with respect to the shaft 35 can be fixed. Accordingly, for example, as will be described later, it is possible to adjust and fix the side surface 33c of the pedestal 33 and the sample surface 3b to be parallel using a stereomicroscope. Accordingly, in the electron microscope 1 using the electron microscope sample stage 31, for example, the measurement surface 3a of the sample 3 attached to the sample mesh 43 shown in FIG. 4 and the incident angle of the electron beam, in other words, the electron beam with respect to the measurement surface 3a. Since the incident angle can be accurately set, highly accurate EBSD analysis can be performed. Note that the measurement surface 3a shown in FIG. 4 corresponds to the measurement surface 102 shown in FIG. 9 described above, and the sample surface 3b corresponds to the sample surface 106 shown in FIG. 9 described above.

<3. Sample preparation and sample mounting>
<3-1. Microsampling method>
The sample 3 attached to the electron microscope sample stage 31 according to the present embodiment is sampled to include an area to be observed by, for example, a microsampling method using a focused ion beam processing apparatus (not shown).

  The micro-sampling method is, for example, using a focused ion beam processing apparatus (not shown) to extract only the sample 3 to be observed including a desired specific part from the sample 49 as shown in FIG. This is a method of fixing to the sample stage 31 using the deposition film 50. For example, the deposition film 50 serves to connect the probe 47 and the sample 3 or to fix the sample 3 to the sample mesh 43. Here, the measurement surface 3 a corresponds to the sample surface 49 a of the sample 49. In the microsampling method, a sample can be reliably captured as compared with a method such as a lift-out method.

  The focused ion beam processing apparatus is intended to scan and irradiate a sample after focusing gallium ions (probe 47) extracted from a gallium ion source (liquid gallium) by an electric field. As a result, atoms and molecules on the sample surface are ejected into a vacuum, and etching that applies this sputtering phenomenon makes it possible to produce a smooth cross-section with a submicron accuracy and drill a hole.

<3-2. Attaching the sample to the sample mesh>
For example, as shown in FIG. 6, the sample mesh 43 is made of a conductive member, and has a shape obtained by cutting a plate into a semicircular shape. As the sample mesh 43, for example, a sample mesh made of molybdenum or copper that is commercially available for FIB can be used. The sample 3 collected by the microsampling method is attached to the sample mesh 43 using the deposition film 50 by the FIB-CVD method.

<3-3. Attaching the sample mesh to the sample table>
For example, as shown in FIG. 7, the sample mesh 43 to which the sample 3 is attached is attached to the upper surface 37 b of the hollow member 37 using a conductive paste 51 having adhesiveness and conductivity. As the conductive paste 51, for example, a carbon paste or a silver paste can be used.

  Specifically, as shown in FIG. 7A, the conductive paste 51 is applied to the end of the upper surface 37 b of the hollow member 37 of the electron microscope sample stage 31. Next, as shown in FIGS. 7B and 7C, the sample mesh 43 with the sample 3 attached on the applied conductive paste 51 is placed so as to protrude from the end of the upper surface 37 b of the hollow member 37. The sample mesh 43 is fixed to the upper surface 37 b of the hollow member 37. FIG. 7B is a side view showing the electron microscope sample stage 31 on which the sample mesh 43 is fixed as shown in FIG. 7C.

  After attaching the sample mesh to the sample table 31 in this manner, the hollow member is observed with a stereomicroscope so that the side surface 33c of the pedestal 33 is parallel to the sample surface 3b of the sample 3 as shown in FIG. Rotate 37 to align direction. Finally, the hollow member 37 and the shaft 35 are fixed by the fixing member 39.

  As described above, by using the electron microscope sample stage 31, the relative position between the hollow member 37 and the shaft 35 can be adjusted easily and accurately. The relative position can be fixed. Thereby, since the incident angle of the electron beam with respect to the measurement surface of the sample 3 can be set accurately, highly accurate EBSD analysis can be performed.

  In the above description, it has been described that the measurement is performed by attaching one sample 3 to the sample mesh 43, but the present invention is not limited to this example, and two or more samples 3 may be attached to the sample mesh 43. For example, even when a plurality of samples 3 are attached to one sample mesh 43, the hollow member 37 can be rotated in the circumferential direction of the shaft 35 as described above, so that one sample 3 is attached to the sample mesh 43. Compared to the case, EBSD measurement of a plurality of samples 3 can be performed more efficiently.

  In the above description, the hollow member 37 is provided with the two through holes 41 and the fixing member 39 is inserted into each of the through holes 41. However, the number of the through holes 41 is one or three. The number of fixing members 39 to be inserted may be changed as appropriate. Further, the shaft 35 has been described as being formed in a columnar shape, but is not limited thereto, and can be appropriately set according to the shape of the hollow portion 37 a in the hollow member 37.

As long as the sample mesh 43 can be attached to the sample mesh 43, for example, a comb-shaped or other shape may be used in addition to the semicircular shape.
<4. Example>

  Hereinafter, specific examples of the present invention will be described. Note that the scope of the present invention is not limited to any of the following examples.

[Example 1]
(1) Sample stand In Example 1, an aluminum cylinder (diameter 4 mm or less) serving as a shaft was connected to the center of an aluminum plate (10 mm × 10 mm × 4 mm) serving as a pedestal. Moreover, the aluminum hollow member (diameter 8 mm x 6 mm) in which the concentric part with a diameter of 4 mm is hollow is inserted into the shaft. The hollow body is provided with a through hole for screwing as a fixing member. By inserting the screw into the through hole, the angle between the shaft and the hollow member, that is, the shaft The relative position with the hollow member is fixed. Moreover, the upper surface of the hollow member is in a smooth surface state.

(2) Preparation of sample and attachment of sample Using a Si substrate with a known crystal orientation, the magnitude of deviation due to fixation of the sample fixed to the sample stage was confirmed.

  Micro sample (20μm × 3μm × 5μm) is extracted from Si substrate by micro sampling method with focused ion beam processing observation device (FB-2100: manufactured by Hitachi High-Technologies) so that the (100) direction becomes the observation surface. An observation sample was prepared.

  The prepared sample was fixed to a sample stage with a conductive paste, and the direction of the sample was adjusted under a stereomicroscope.

(3) Orientation analysis of the sample by EBSD As shown in FIG. 8, the orientation analysis of the sample 3 is performed using the EBSD system (CHANEL5) mounted on the SEM (ULTRA55: manufactured by Carl Zeiss), and the (100) direction of Si The magnitude of the inclination with respect to was measured.

[Comparative Example 1]
In Comparative Example 1, an observation sample was prepared in the same manner as in Example 1, and fixed to the upper surface of an aluminum (Al) cube (10 mm × 10 mm × 10 mm) with a conductive paste. Next, orientation analysis was performed using the same EBSD system as in Example 1, and the tilt of Si with respect to the (100) direction was measured.

  The measurement results of Example 1 and Comparative Example 1 are shown in Table 1 below.

  As shown in Table 1, it can be seen that the measurement result of Example 1 is smaller than the measurement result of Comparative Example 1 due to the fixation of the sample fixed to the sample stage. From these results, it was found that by using the sample stage of Example 1, highly accurate EBSD analysis can be performed.

  1 electron microscope, 3 sample, 5 sample stage, 7 electron beam irradiation unit, 9 sample holder, 11 CCD camera, 13 stage control unit, 15 camera control unit, 17 system control unit, 19 electron gun, 21 focusing lens, 23 objective Lens, 25 Scanning coil, 31 Electron microscope sample base, 33 base, 34 Sample base mounting part, 35 axis, 37 hollow member, 37a hollow part, 39 fixing member, 41 through hole, 43 sample mesh, 45 sample, 47 probe , 49 samples, 50 deposition film, 51 conductive paste, 100 samples, 102 measurement surface, 104 detector, 106 sample surface

Claims (5)

A pedestal attached to a sample holder that can be mounted on a sample stage of an electron microscope;
An axis fixed perpendicular to the pedestal;
A hollow portion extending in the axial direction inside the main body is formed, and at least one through hole is formed on the side surface of the main body trunk portion, inserted into the shaft through the hollow portion, and inserted into the shaft. A hollow member rotatable in the circumferential direction of the shaft,
A fixing member that is inserted into the through-hole and supports the shaft and the hollow member to fix a relative position between the hollow member and the shaft;
A sample stage for an electron microscope, wherein a sample is attached to an upper surface of the hollow member. The pedestal and the hollow member are formed so that the lower surface of the pedestal in contact with the sample holder and the upper surface of the hollow member are parallel to each other,
When the angle of the sample stage is controlled by the stage controller, the angle of the measurement surface of the sample with respect to the incident direction of the electron beam is controlled via the sample holder and the electron microscope sample stage. The sample stage for an electron microscope according to claim 1, characterized in that:   The sample stage for an electron microscope according to claim 1 or 2, wherein the sample is produced by a microsampling method using an FIB processing apparatus.   The sample stage for an electron microscope according to claim 3, wherein the sample is attached to a sample mesh using a deposition film formed by FIB-CVD.   The sample stage for an electron microscope according to claim 4, wherein the sample mesh is attached to an upper surface of the hollow member using a conductive paste.

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