Method for preparing sample for transmission electron microscope observation using reinforcing ring, and transmission electron microscope observation method

Abstract

To provide a manufacturing method of a sample for TEM observation using a reinforcing ring in which the manufactured sample for TEM observation is not contaminated with Si while maintaining excellent workability in the manufacturing method of the sample for TEM observation, and to provide a TEM observation method using the manufacturing method of the sample for TEM observation using the reinforcing ring SOLUTION: The method includes the steps of: providing a carbon thin film on a base; bonding a sheet mesh onto the carbon thin film to fix the sheet mesh on the base; bonding a C-shaped reinforcing ring onto the sheet mesh; placing a sample in a hole of the sheet mesh and fixing the sample in the hole; scratching the carbon thin film along an outer periphery of the sheet mesh; and peeling the sheet mesh from the base to obtain a cured sample.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a method for preparing a specimen for observation with a transmission electron microscope using a reinforcing ring, and a method for observation with a transmission electron microscope. [Background technology]

[0002] With the development of the electronics industry, precise information is required about the physical properties, state of change, etc. of various materials used in this field. Observation by transmission electron microscope (sometimes referred to as "TEM" in this invention) is considered to be an effective means of obtaining such information.

[0003] When observing materials made of various materials and having various shapes such as powder, sheet, and flake using a TEM, it is necessary to use the materials as samples for TEM observation. As a method for preparing such a sample for TEM observation, for example, a method proposed in Patent Document 1 has been known.

[0004] However, according to the investigations of the present inventors, the above-mentioned conventional techniques have the following problems. 1. Sample processing using an ion milling device (sometimes referred to as "IM" in this invention) is limited to processing the cross section of the sample. For this reason, if the sample is sheet- or flake-shaped, a thin section for TEM observation must be prepared in a very narrow area within the sample, making IM processing extremely difficult (if IM processing is stopped too early, the target sample section will be too thick and unsuitable for TEM observation. On the other hand, if IM processing is stopped too late, the observed portion of the sample will be lost due to IM processing). 2. When cutting the laminate to the specified thickness (approximately 100 μm) after the adhesive has hardened, cracks and chips are likely to occur. 3. When a sample after IM processing is attached to, for example, a C-shaped reinforcing ring, the thin part of the sample is easily damaged. 4. TEM observation sometimes requires a well-oriented sample. In such cases, a large observation area is required on the thin section, so multiple sample chips must be prepared.

[0005] In order to solve the above-mentioned problems, the inventors came up with a configuration in which a sample is fixed to a sheet mesh used to load the sample into a TEM, and then IM processing is performed on the sheet mesh to which the sample is fixed, and disclosed Patent Document 2. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-98088 [Patent Document 2] Patent Publication No. 2021-156878 Summary of the Invention [Problem to be solved by the invention]

[0007] The method for preparing samples for TEM observation that the inventors disclosed in Patent Document 2 was an excellent method in that it took advantage of the releasability and flexibility of the silicone sheet to easily peel off a cured sample prepared on the surface of the silicone sheet, which could then be easily attached to a TEM, and the cured sample could be easily prepared with a thin section having a thickness and field of view suitable for TEM observation.

[0008] However, further investigation by the present inventors has revealed that TEM observation samples prepared by the method for preparing TEM observation samples disclosed in Patent Document 2 may be contaminated with Si (silicon).

[0009] The present invention was made under the above circumstances, and the problem to be solved by the present invention is to provide a method for preparing a TEM observation sample using a reinforcing ring, which maintains excellent workability while preventing the TEM observation sample from being contaminated with Si, and a TEM observation method using the method for preparing a TEM observation sample using the reinforcing ring. [Means for solving the problem]

[0010] That is, the first invention for solving the above-mentioned problems is: providing a carbon thin film on a substrate; a step of adhering a sheet mesh onto the carbon thin film and fixing the sheet mesh on the base; Adhering a C-shaped reinforcing ring onto the sheet mesh; placing a sample in a hole in the sheet mesh and fixing the sample in the hole; scratching the carbon thin film around the outer periphery of the sheet mesh along the outer periphery of the sheet mesh; and a step of peeling off the sheet mesh from the base to obtain a hardened sample. The second invention is: This is a method for preparing a sample for observation by transmission electron microscope using the reinforcing ring described in the first invention, characterized in that in the process of placing a sample in the hole of the sheet mesh and fixing it in the hole, and in the process of peeling the sheet mesh off the base and obtaining the hardened sample, the occurrence of distortion in the sheet mesh is suppressed by the C-shaped reinforcing ring. The third invention is This is a method for preparing a sample for transmission electron microscope observation using the reinforcing ring described in the first or second invention, characterized in that when loading the hardened sample into an ion milling device, the open end of the C-shaped reinforcing ring is placed opposite the ion gun of the ion milling device. The fourth invention is The method for preparing a sample for transmission electron microscope observation using a reinforcing ring according to the first invention is characterized in that the sample is a powder sample. The fifth invention is The method for preparing a sample for transmission electron microscope observation using a reinforcing ring according to the first invention is characterized in that the sample is a sheet-like or flake-like sample. The sixth invention is The method for preparing a sample for transmission electron microscope observation using a reinforcing ring according to the first invention is characterized in that the sample is a coated body in which sample powder is coated on a metal foil. The seventh invention is a step of fixing a coated body in which the sample powder is coated on a metal foil in the hole, and then a step of peeling the metal foil from the coated body; A method for preparing a sample for transmission electron microscope observation using a reinforcing ring according to the sixth invention, characterized in that in the process of peeling off the metal foil, the C-shaped reinforcing ring suppresses the occurrence of distortion in the sheet mesh. The eighth invention is This is a transmission electron microscope observation method characterized by performing transmission electron microscope observation using a transmission electron microscope observation sample prepared by the method for preparing a transmission electron microscope observation sample using the reinforcing ring described in the first invention. [Effects of the Invention]

[0011] According to the present invention, a sample that can be easily mounted on a TEM and has a thin section with a thickness and field of view area suitable for observation by a TEM can be simply prepared without being contaminated with Si. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of a sheet mesh having one slot hole. [Figure 2] FIG. 1 is a plan view of a C-shaped reinforcing ring. [Figure 3] FIG. 1 is a cross-sectional view of a sheet mesh adhered to a carbon thin film provided on a glass slide. [Figure 4]FIG. 10 is a cross-sectional view of a sheet mesh adhered to a carbon thin film provided on a slide glass, the sheet mesh being filled with a kneaded sample. [Figure 5] FIG. 2 is a perspective view of a sample (coated body) to be observed. [Figure 6] FIG. 10 is a cross-sectional view of a sample powder coated on a metal foil fixed to a sheet mesh adhered to a carbon thin film provided on a glass slide. [Figure 7] 10 is a cross-sectional view showing a state where a metal foil is peeled off from a coated body in which a sample powder is coated on the metal foil. FIG. [Figure 8] FIG. 1 is a cross-sectional view of a hardened sample (kneaded material) peeled off from a slide glass. [Figure 9] FIG. 1 is a cross-sectional view of a cured sample (coated body) peeled off from a slide glass. [Figure 10] FIG. 1 is a perspective view of a hardened sample being irradiated with an argon ion beam. [Figure 11] FIG. 1 is a cross-sectional view of a hardened sample being irradiated with an argon ion beam. [Figure 12] FIG. 1 is a perspective view of a hardened sample after argon ion beam irradiation. [Figure 13] FIG. 1 is a cross-sectional view of a hardened sample after argon ion beam irradiation. [Figure 14] FIG. 1 is a front view of a hardened sample placed on a TEM sample holder after argon ion beam irradiation. DETAILED DESCRIPTION OF THE INVENTION

[0013] The embodiments for carrying out the present invention will be described in the following order: 1. Cause of sample contamination by Si, and 2. Preparation of a sample for TEM observation using a reinforcing ring according to the present invention.

[0014] 1. Causes of sample contamination by Si The present inventors have investigated the cause of the case where a TEM observation sample prepared by the method for preparing a TEM observation sample disclosed in Patent Document 2 is contaminated with Si. As a result, we concluded that the cause of the Si contamination was that in the process of preparing samples for TEM observation, a sheet mesh was placed on top of a silicone sheet, the sample was inserted into the holes in the sheet mesh, and both the sheet mesh and the sample were brought into close contact with the silicone sheet, after which a filler was filled in and cured.

[0015] However, by adhering both the sheet mesh and the sample to the silicone sheet and then filling and curing the filler, it was possible to prevent the sample from floating up in the filler, and the underside of the sheet mesh and the top surface of the sample were aligned flat, providing an optimal condition for subsequent processing by IM. Furthermore, once the filler had cured and the sample was fixed within the holes in the sheet mesh (in this invention, the state in which the sample was placed within the holes in the sheet mesh and fixed within the holes in the sheet mesh by the filler is sometimes referred to as a "cured sample"), the silicone sheet and the cured sample were to be separated, but because general fillers do not adhere to silicone sheets, the silicone sheet and the cured sample could be easily separated.

[0016] However, we realized that the cured sample may be contaminated with Si contained in the silicone sheet when both the sheet mesh and the sample were attached to the silicone sheet, filled with filler, and cured. Specifically, when the cured sample was processed by IM, silicon (such as fine silicon edges) from the silicone sheet that adhered to the surface of the cured sample in contact with the silicone sheet penetrated into the grain boundaries of the sample for TEM observation, causing the contamination with Si.

[0017] 2. Preparation of TEM observation samples using the reinforcing ring according to the present invention Based on the above findings, the inventors have researched a method for producing TEM specimens without using a silicone sheet, which is as productive as the method using a silicone sheet and which also provides optimal conditions for subsequent IM processing. They have come up with the idea of ​​using a carbon thin film to impart conductivity to TEM specimens.

[0018] That is, a carbon thin film having a thickness of 40 nm or more, preferably 80 nm or more, is formed on a suitable substrate, a sheet mesh is placed on the carbon thin film, and the sheet mesh and carbon thin film are bonded together using an adhesive to fix the sheet mesh to the substrate. A mixture obtained by mixing a sample and a filler is then inserted into the holes of the sheet mesh, the mixture is brought into close contact with the carbon thin film, and the filler is then filled and cured. Alternatively, the sheet mesh is placed on the carbon thin film, and the sample is then inserted into the holes of the sheet mesh, and both the sheet mesh and the sample are brought into close contact with the carbon thin film, and the filler is then filled and cured.

[0019] After the filler has hardened, a knife or the like is used to make a scratch on the carbon thin film on the outer periphery of the sheet mesh fixed on the substrate, going all the way around the outer periphery of the sheet mesh.Then, the knife or the like is inserted into the gap between the sheet mesh and the substrate and gouged to peel the sheet mesh off from the substrate, thereby obtaining a hardened sample, which is a method of preparing a sample for TEM observation.

[0020] When the sheet mesh is peeled off from the substrate, a thin carbon film may remain on the obtained cured sample. However, since this thin carbon film is the same as the thin carbon film used to impart conductivity to a TEM observation sample, the TEM observation sample is not contaminated with Si, and the method for preparing a TEM observation sample does not interfere with the observation when the TEM observation sample is observed using a TEM.

[0021] However, as a result of further investigation by the present inventors, it was found that in the above-mentioned method for preparing a sample for TEM observation, a sheet mesh is used as a shielding plate in the IM processing step described below, rather than using the shielding plate provided in the IM. Therefore, if distortion occurs in the sheet mesh during the IM processing step, there may be areas in the sample where the beam, such as an argon beam, is not irradiated, resulting in unprocessed areas, which may be a problem.

[0022] They discovered that such distortion of the sheet mesh is caused by the thin and soft sheet mesh, which is 12 to 15 μm thick, and is the result of artificial operations such as peeling the sheet mesh from the substrate and subsequent processing of the sample, as well as thermal contraction of the thermosetting resin filler.

[0023] The inventors therefore conducted research and came up with the idea of ​​mechanically reinforcing the sheet mesh using a C-shaped reinforcing ring with a thickness of approximately 50 μm, which has an outer diameter approximately the same as that of the sheet mesh, an inner diameter approximately the same as that of the slot portion of the sheet mesh, and thus completed the present invention.

[0024] The following describes the method for preparing a sample for TEM observation using the reinforcing ring of the present invention, with reference to the drawings, in the following order: (1) the sample to be observed, (2) the sheet mesh, (3) the C-shaped reinforcing ring, (4) the filler, (5) the base, (6) the placement of a carbon thin film on the base, (7) the fixing of the sheet mesh to the base and reinforcement with the C-shaped reinforcing ring, (8) the placement and fixation of the sample on the reinforced sheet mesh, (9) the peeling of the reinforced hardened sample from the base, (10) the processing of the reinforced hardened sample by IM, and (11) the loading into the TEM and analysis.

[0025] (1) The sample to be observed The present invention is widely applicable to samples made of a wide variety of materials, such as metals, alloys, oxides, carbides, fluorides, chlorides, borides, sulfides, nitrides, organic materials, and composites of two or more of these materials. The present invention can be applied to samples of various shapes, but it can also be preferably applied to samples in the form of sheets or flakes, or metal foils coated with powders of oxides, carbides, fluorides, chlorides, borides, sulfides, nitrides, etc., which have been difficult to prepare for TEM observation using conventional techniques.

[0026] (2) Sheet mesh Sheet mesh is essentially a small circular wire mesh that is loaded into a TEM with the sample to be observed on it. There are a variety of meshes available commercially, each with a different material and mesh shape. The sheet mesh size should be 3 mm in outer diameter, which is convenient for loading into a TEM sample holder (described later). The thickness of the sheet mesh should be 10 μm to 50 μm, which is convenient for mechanical strength and ease of processing by IM (intermesh machining) (described later).

[0027] In the present invention, a sheet mesh having holes is used. The number, size, and shape of the holes in the sheet mesh can be selected as desired depending on the size and shape of the sample. However, from the viewpoint of facilitating the subsequent IM processing, it is generally preferable to use a disk-shaped sheet mesh having a single hole or one slot.

[0028] Two perspective views of a disk-shaped sheet mesh 11 having one slot 13 as a hole portion are shown in FIG. 1(a) and FIG. 1(b). There are two types of sheet mesh: one with a hole in the center, as shown in Fig. 1(a), and one with a single oval slot centered in the center, as shown in Fig. 1(b). In the sheet mesh shown in Fig. 1(a), the diameter of the hole in the center is preferably 0.3 to 0.8 mmφ, and even 1 mmφ, while in the sheet mesh shown in Fig. 1(b), the size of one slot is preferably about 1 mm × 2 mm. This is because it often makes sample trimming, as described below, easier, and is convenient from the viewpoint of ensuring a field of view during TEM observation, as described below.

[0029] On the other hand, as will be described later, when filling the holes of a sheet mesh with a mixture of a powder sample and a filler, it is convenient to use a single-hole sheet mesh.

[0030] Copper is the most common material for the sheet mesh, but other materials are available, such as nickel, gold, molybdenum, copper, carbon, polymer materials, etc. There are no particular restrictions on the material of the sheet mesh, except that it must have a spectrum that does not overlap with the spectrum of X-rays emitted from the sample during TEM observation, as described below.

[0031] (3) C-shaped reinforcement ring A plan view of the C-shaped reinforcing ring is shown in Figure 2. The C-shaped reinforcing ring 18 is a metal disk having an outer diameter similar to that of the sheet mesh, and has a hole with an inner diameter approximately the same as that of the slot in the sheet mesh, an open end 19 of the C-shaped reinforcing ring having a width equal to that inner diameter, and a thickness of approximately 50 μm. The metal used for the C-shaped reinforcing ring is the same as that used for the sheet mesh. As a result, even when the sheet mesh is reinforced by bonding the C-shaped reinforcing ring 18, it can be loaded directly into the TEM sample holder described below.

[0032] The C-shaped reinforcing ring 18 used in the present invention is conveniently a C-shaped reinforcing ring commercially available for use with cryo-ion slicers manufactured by JEOL Ltd., which is used to fix a sliced ​​sample to a sheet mesh after slicing the sample using a microtome or the like.

[0033] (4) Filler As a filler for fixing the sample in the holes of the sheet mesh, a material that is liquid or gel-like under the atmosphere when filling between the sheet mesh and the sample, and hardens after filling to fix the sample in the holes of the sheet mesh, such as a room temperature curing or heat curing resin or adhesive, or a UV resin that hardens when exposed to UV light, can be preferably used. The types of these resins and adhesives are not particularly limited, as long as they have strength that does not interfere with TEM observation and do not have any chemical effect on the sample. Among them, epoxy resins, which are heat-curable resins, are preferred because of their ease of use.

[0034] (5) Foundation There are no particular limitations on the material as long as it has mechanical strength and does not interfere with TEM observation, but in general, a glass slide is preferred.

[0035] (6) Placing a carbon thin film on the substrate In the present invention, a carbon thin film is formed and placed on a substrate. If the carbon thin film has a thickness of 40 nm or more, the cured sample can be peeled off from the substrate in a subsequent process. From this perspective, the carbon thin film preferably has a thickness of 80 nm or more and 200 nm or less. If the carbon thin film has a thickness of 40 nm or more, preferably 80 nm or more, the cured sample can be easily peeled off. On the other hand, even if a carbon thin film is formed with a thickness exceeding 200 nm, the effect of facilitating peeling of the cured sample is saturated. Forming a carbon thin film with a thickness exceeding 200 nm requires time and effort and is not cost-effective. There are no particular limitations on the method for forming the carbon thin film, but from the viewpoint of peeling the cured sample from the substrate in a subsequent process by peeling the carbon thin film from the substrate, a vapor-deposited film, which has weaker adhesion to the substrate, is preferable to a sputtered film, which has strong adhesion to the substrate. The conditions for forming the carbon thin film are the same as those for forming the conductive thin film when preparing the sample for TEM observation.

[0036] (7) Fixing the sheet mesh onto the base and reinforcing it with a C-shaped reinforcing ring An adhesive is applied to the sheet mesh, which is then placed on and adhered to a substrate on which a carbon thin film has been formed. A thermosetting resin is convenient as the adhesive. Then, as shown in Figure 3, which is a cross-sectional view of the sheet mesh adhered to a carbon thin film provided on a glass slide, the sheet mesh 11 to which adhesive 16 has been applied is placed on a substrate 17 on which a carbon thin film 15 has been formed.

[0037] Furthermore, a C-shaped reinforcing ring 18 coated with adhesive 16 is placed on the sheet mesh 11 . At this time, by placing the sheet mesh 11 so that its outer diameter matches the outer diameter of the C-shaped reinforcing ring 18, the slots of the sheet mesh 11 and the openings of the C-shaped reinforcing ring 18 overlap.

[0038] Next, the base 17 on which the sheet mesh 11 and the C-shaped reinforcing ring 18 were placed was heated to harden the adhesive 16, thereby fixing the sheet mesh 11 onto the carbon thin film 15 formed on the base, and the C-shaped reinforcing ring 18 was further fixed onto the sheet mesh 11, thereby reinforcing the sheet mesh 11.

[0039] (8) Placement and fixation of the sample on the reinforced sheet mesh The placement and fixation of a sample on a reinforced sheet mesh will be explained with reference to the drawings, which are schematic cross-sectional views of a hardened sample at each step of the sample placement and fixation process, for the following cases: (1) when the sample is a powder; (2) when the sample is in sheet or flake form; and (3) when the sample powder is a coating applied to a metal foil.

[0040] <1> When the sample is powder The powder sample to be measured is mixed and kneaded with a filler to obtain a mixture of the powder sample and filler. The composition of the mixture is such that the powder sample is mixed with the filler at a volume ratio of 1:1 or more and 5:1 or less, preferably 2:1 or more and 4:1 or less. This is because more particles can be observed during TEM observation. As shown in FIG. 4, which is a cross-sectional view of a sheet mesh adhered to a carbon thin film provided on a glass slide, the sample (kneaded material) 20 is filled into the holes 14 of the sheet mesh, and the filler is hardened to obtain a hardened sample. During this hardening, the sheet mesh 11 was reinforced by the C-shaped reinforcing ring 18, so that the occurrence of distortion due to shrinkage of the filler was suppressed.

[0041] <2> When the sample is in sheet or flake form The sheet- or flake-shaped sample to be measured is trimmed to a size that can be inserted into the holes 14 of the sheet mesh, which may be reinforced if necessary. The sample (sheet or flake-shaped) is then inserted into the holes 14 of the sheet mesh. A filler is then filled between the sample (sheet or flake-shaped) and the holes 14 of the sheet mesh, and the filler is hardened to obtain a hardened sample. During this hardening, the sheet mesh 11 was reinforced by the C-shaped reinforcing ring 18, so that the occurrence of distortion due to shrinkage of the filler was suppressed.

[0042] <3> When the sample powder is coated on a metal foil 5, which is a perspective view of a sample (coated body) to be observed, shows a sample (coated body) 21, which is a sheet-like sample in which a coated body 22 (shown in black) containing a metal oxide is provided on a metal foil 23 (shown in gray). First, the sample (coated body) 21 is trimmed with a design knife or the like to a size that can be inserted into the holes of a reinforced sheet mesh. The shape of the trimmed sample (coated body) 21 may be arbitrary, but it is preferable that it be close to the shape of the holes 14 of the sheet mesh.

[0043] The operation of inserting the sample (coated body) 21 into the hole of the reinforced sheet mesh will be described with reference to Figure 6, which is a cross-sectional view of a coated body in which sample powder is coated on a metal foil, fixed to a sheet mesh adhered to a carbon thin film provided on a slide glass. The trimmed sample (coated body) 21 is placed in the hole 14 of the sheet mesh. At this time, it is preferable that the lower surface of the sheet mesh 11 and the upper surface of the coated body 22 of the sample (coated body) 21 are aligned in a plane, and the surface of the coated body 22 is placed in a direction that contacts the carbon thin film 15, and the surfaces are mated. Then, the gap between the inner wall of the hole 14 of the sheet mesh and the trimmed sample (coated body) 21 is filled with a filler 32, and the filler 32 is hardened by an appropriate method to obtain a hardened sample. During this hardening, the sheet mesh 11 was reinforced by the C-shaped reinforcing ring 18, so that the occurrence of distortion due to shrinkage of the filler was suppressed.

[0044] Next, peeling of the metal foil from the coated body will be described with reference to FIG. 7, which is a cross-sectional view showing the process of peeling the metal foil from the coated body in which the sample powder is coated on the metal foil. The reason for peeling off the metal foil 23 attached to the sample (coated body) 21 here is to avoid the metal atoms constituting the metal foil 23 being redeposited on the sample (coated body) 21 and contaminating the sample when the hardened sample is processed using IM in the subsequent process.

[0045] The metal foil 23 adhering to the sample (coated body) 21 is lifted from the end of the sample using a design knife 26 or the like, and is then rolled up to peel off the entire metal foil 23. At this time, the metal foil 23 is peeled off little by little so as to generate as little stress as possible in the sample (coated body) 21. However, since the sample (coated body) 21 is fixed to the sheet mesh 11 by the filler 32, and the sheet mesh 11 is integrated with the base 17 via the carbon thin film 15 by the adhesive 16, and further reinforced by the C-shaped reinforcing ring 18, the sample (coated body) is mechanically stable, and the peeling operation can be carried out easily.

[0046] (9) Peeling of the reinforced hardened specimen from the substrate As described above, when the sample is in the form of powder, or when the sample is in the form of a sheet or flake, the hardened sample 31 is peeled off from the base 17 as shown in FIG. 8, which is a cross-sectional view of the hardened sample (kneaded material) peeled off from the slide glass, or when the sample powder is in the form of a coating applied to a metal foil, as shown in FIG. 9, which is a cross-sectional view of the hardened sample (coated material) peeled off from the slide glass.

[0047] Specifically, a design knife 26 or the like is used to make scratches along the outer periphery of the carbon thin film 15 on the outer periphery of the sheet mesh 11. Then, the design knife 26 or the like is inserted into the gap between the sheet mesh 11 and the base 17 and gouged, thereby peeling off the hardened sample 31 from the base 17. During this peeling operation, the sheet mesh 11 is reinforced by a C-shaped reinforcing ring 18, so that the occurrence of distortion is suppressed.

[0048] At this time, it is believed that the carbon thin film 15 peels off from the substrate 17 together with the cured sample 31 and adheres to the underside of the cured sample 31. However, since the carbon thin film 15 is similar to the carbon thin film provided as a conductive thin film on a TEM observation sample, it does not interfere with the TEM observation in the subsequent process.

[0049] (10) Processing of reinforced hardened specimens by IM Processing of hardened sample 31 using IM will be described with reference to FIGS. The subsequent steps are the same for (1) the sample being a powder, (2) the sample being a sheet or flake, and (3) the sample powder being a coating on a metal foil. Therefore, in the subsequent steps, the above-mentioned sample (kneaded material) 20, the cured product of the filler in the sheet-like and flake-like samples, and the sample (coated body) 21 will be collectively referred to as sample 24.

[0050] The processing of the disk-shaped hardened sample 31 using IM is performed using one or more ion beams selected from argon, gallium, and xenon, but for convenience, the present specification will be described using an argon ion beam as an example. Note that the following description also applies to the case where a gallium or xenon ion beam is used as the ion beam.

[0051] First, the loading of the hardened sample 31 into the IM and the irradiating of the hardened sample with an argon ion beam will be described with reference to FIG. 10, a perspective view thereof, and FIG. 11, a cross-sectional view thereof. When loading the disk-shaped hardened sample 31 into the IM, the side of the sheet mesh 11 of the hardened sample 31 faces the ion gun of the IM, and the open end 19 of the C-shaped reinforcing ring faces the ion gun of the IM. Meanwhile, the shielding plate equipped on the IM is not used.

[0052] 10 and 11, an argon ion beam 41 is irradiated from the ion gun onto the hardened sample 31 and the sheet mesh 11. The argon ion beam 41 then cuts and slices the portion 12 of the sheet mesh on the ion gun side and the sample 24. At this time, the lower surface of the sheet mesh 11 and the upper surface of the sample 24 are aligned and face-to-face in a plane, so the portion 12 of the sheet mesh on the ion gun side functions as a shielding plate. This is preferable from the viewpoint of preventing the sample 24 from being significantly cut and lost by the argon ion beam 41 from the start of irradiation.

[0053] On the other hand, because the open end 19 of the C-shaped reinforcing ring faces the ion gun of the IM, the argon ion beam 41 is not irradiated onto the C-shaped reinforcing ring 18, but is irradiated onto the hardened sample 31 and the sheet mesh 11. As a result, the C-shaped reinforcing ring 18 is preferable because it does not affect the IM processing and does not extend the IM processing time.

[0054] At this time, the ion gun is suitably moved back and forth (swung) around the center of the sheet mesh 11, or the sheet mesh 11 is rotated eccentrically. By this movement, as shown in Figures 10 and 11, it is possible to irradiate the sample 24 with the argon ion beam 41 while varying within a range of values ​​of θ, which is the range of variation of the angle of incidence when the argon ion beam 41 is incident on the sample 24. Note that when the argon ion beam 41 is incident on the sample 24, the value of the range of variation of the angle of incidence θ is in the range of 0° to 20°, preferably in the range of approximately 0.5° to 5°.

[0055] The hardened sample at the time when the thinning by the argon ion beam is completed will be described with reference to FIG. 12, which is a perspective view of the hardened sample after argon ion beam irradiation, and FIG. 13, which is a cross-sectional view thereof. The sample 24 is thinned by the argon ion beam while the ion gun side portion of the sheet mesh 11 functions as a shield, resulting in a slice having a thickness of 0.005 to 0.1 μm, with the center being perforated 25 to provide a thickness suitable for a sample for TEM observation. Furthermore, the sliced ​​portion of the sample 24 has an area of ​​about 0.5 × 1 mm, which provides a sufficient field of view for a sample for TEM observation.

[0056] Furthermore, since the IM processing is performed on the hardened sample 31 without any mechanical processing such as cutting with a knife, the work is easy and highly productive, and the possibility of mechanical damage to the sample 24 is avoided. On the other hand, the portion of the sample 24 on the ion gun side is irradiated with the argon ion beam 41 and thinned, making it very brittle. However, because this portion is formed within the slots of the reinforced sheet mesh 11, the hardened sample 31 can be easily handled without receiving any mechanical shock to this portion.

[0057] (11) TEM loading and analysis FIG. 14 is a front view of the hardened sample placed on the sample holder of the TEM after argon ion beam irradiation. As shown in FIG. 14, the hardened sample 31 that has been processed by IM is loaded into a sample holder 61 of the TEM. Since the sample 24 is surrounded by the reinforced sheet mesh 11, the hardened sample 31 is loaded in this state into the sample holder 61 of the TEM without applying any mechanical shock to the relevant part. Furthermore, the sheet mesh 11 is also reinforced by a C-shaped reinforcing ring 18, and the sample for TEM observation is made using a reinforcing ring, so that the occurrence of distortion is suppressed.

[0058] It is also possible that metal elements evaporated from the ion gun side portion of the sheet mesh 11, which has been thinned by the argon ion beam, may adhere to the ion gun side portion of the sample 24. Therefore, this problem can be avoided by selecting a material for the sheet mesh 11 that has an X-ray spectrum that does not overlap with the X-ray spectrum of the powder sample to be observed.

[0059] As described above, the thickness of the thinned sample 24 on the ion gun side is suitable for use as a sample for TEM observation, and the sample has an area that provides a sufficient field of view, allowing for precise observation as desired. [Example]

[0060] The present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. Example 1 1. The sample to be observed Ruthenium oxide powder (particle size: approximately 0.05 μm) was prepared as a sample (powder sample). 2. Sheet mesh A sheet mesh (#09-1039) manufactured by Oken Shoji Co., Ltd. was prepared. This is a sheet mesh made of molybdenum (Mo) whose EDS spectrum does not overlap with that of the sample to be observed, and has a single hole with a diameter of 0.5 mm, as shown in Figure 1(a). 3.C-shaped reinforcement ring A C-shaped reinforcing ring (AT-5-2710-4) manufactured by JEOL Ltd. was prepared. This C-shaped reinforcing ring was made of Mo, and its EDS spectrum did not overlap with that of the sample to be observed. It had the same outer diameter as the sheet mesh, a 1.5 mm diameter hole, a 1.5 mm wide open end, and a thickness of 50 μm. 4. Fillers As a filler, an epoxy resin (G2) manufactured by Gatan, Inc. was prepared. 5. Foundation A glass slide measuring 48 × 28 × 1.2 to 1.5 mm was prepared as a substrate.

[0061] 6. Placing carbon thin film on the substrate The substrate was placed in a vacuum deposition apparatus (VE-2012 manufactured by Vacuum Device Co., Ltd.), and a carbon thin film was formed on the substrate by vacuum deposition. The carbon thin film had a thickness of 80 nm.

[0062] 7. Fixing the sheet mesh onto the base and reinforcing it with a C-shaped reinforcing ring A thermosetting resin (epoxy resin (G2) manufactured by Gatan, Inc.) was applied as an adhesive to the sheet mesh, which was then placed on a base with a carbon thin film. Next, a thermosetting resin (epoxy resin (G2) manufactured by Gatan, Inc.) was applied as an adhesive to a C-shaped reinforcing ring, which was then placed on the sheet mesh. The base on which the sheet mesh was placed was then heated to harden the thermosetting resin, fixing the sheet mesh to the base, and the sheet mesh was reinforced by the C-shaped reinforcing ring.

[0063] 8. Mounting and Fixing the Specimen on the Reinforced Sheet Mesh The kneaded material obtained by kneading the sample and filler in advance was filled into the holes of a reinforced sheet mesh fixed on a base, and the filler was cured to fix the sample (kneaded material) in the holes of the sheet mesh. At this time, no distortion of the sheet mesh due to shrinkage accompanying the curing of the filler occurred.

[0064] 9. Peeling of the reinforced cured sample from the substrate The carbon thin film on the outer periphery of the sheet mesh fixed on the substrate was scratched around the entire periphery of the sheet mesh using a design knife or the like. The design knife or the like was then inserted into the gap between the sheet mesh and the substrate and gouged, peeling the sheet mesh from the substrate to obtain a cured sample. At this time, the carbon thin film was also peeled from the substrate together with the cured sample. Furthermore, no distortion of the sheet mesh occurred during this peeling operation.

[0065] 10. Processing of Reinforced Hardened Specimens by IM The obtained hardened sample was placed in an IM device (Ion Slicer IB09060CIS, manufactured by JEOL Ltd.). At this time, the open end of the C-shaped reinforcing ring was placed opposite the ion gun, and the shielding plate attached to the device was not used; instead, the part of the sheet mesh facing the ion gun acted as a shielding plate. Then, the hardened sample was irradiated with an argon ion beam from the IM ion gun (the range of the incident angle when the argon ion beam was incident on the sample was θ: 0.5° to 4.0°) to thin the sample (kneaded material).

[0066] 11. Loading into TEM and Analysis The sample for TEM observation using the reinforcing ring after thinning by IM was loaded into a TEM sample holder and placed in a TEM (JEOL Ltd., JEM-ARM200F). The film thickness of the upper part of the sample (kneaded material) that had been thinned by the argon ion beam was suitable for use as a sample for TEM observation, and the area provided a sufficient field of view, allowing for precise observation of the sample to be observed.

[0067] Example 2 1. The sample to be observed As a sample (sheet-shaped sample), a metal foil (metal foil with a thickness of approximately 10 μm) was coated with transition metal oxide powder and conductive additives, etc., to a thickness of approximately 100 μm, forming a coated body to be observed. 2. Sheet mesh A sheet mesh (#09-1059) manufactured by Oken Shoji Co., Ltd. was prepared. This is a molybdenum (Mo) sheet mesh whose EDS spectrum does not overlap with that of the sample to be observed, and has one slot (slot size: 1 mm × 2 mm) as shown in Figure 1(b).

[0068] 3.C-shaped reinforcement ring The C-shaped reinforcing ring is the same as in Example 1. 4. Fillers The filler was the same as in Example 1. 5. Foundation The substrate is the same as in the first embodiment. 6. Placing carbon thin film on the substrate The same procedure as in Example 1 was carried out. 7. Fixing the sheet mesh onto the base and reinforcing it with a C-shaped reinforcing ring The same procedure as in Example 1 was carried out.

[0069] 8. Mounting and Fixing the Specimen on the Reinforced Sheet Mesh <1> Using a design knife, the sample (sheet-shaped sample) was trimmed to a size that would fit into the holes in the sheet mesh (a long octagon with a length of 0.9 mm and a width of 1.7 mm). Although the sample was not limited to being trimmed into a long octagon, this shape was preferable from the viewpoint of inserting the sample into the holes in the sheet mesh.

[0070] <2> The long side of the trimmed sample was aligned with the hole in the sheet mesh, and the sample was inserted into the hole in the sheet mesh with the surface to be observed (the coated surface) facing the carbon thin film side.

[0071] <3> Filler was filled into the gap between the trimmed sample piece and the hole wall of the sheet mesh, and the filler was cured by heating on a hot plate at 125°C for 15 minutes, and the trimmed sample was fixed to the sheet mesh. At this time, no distortion of the sheet mesh occurred due to shrinkage caused by the curing of the filler.

[0072] 9. Metal foil peeling operation Using a design knife, the metal foil adhering to the trimmed sample was lifted from the edge of the sample, and then rolled up to peel off the entire metal foil. At this time, the metal foil was peeled off little by little so as to minimize stress on the trimmed sample (coated body). However, the sheet mesh of the cured sample was integrated with the base by adhesive and further reinforced with a C-shaped reinforcing ring, so it was mechanically stable and the peeling operation could be carried out easily.

[0073] 10. Peeling off the sheet mesh from the base The procedure was carried out in the same manner as in Example 1. During this peeling operation, the sheet mesh was reinforced with a C-shaped reinforcing ring, so that the occurrence of distortion was suppressed.

[0074] 11. Processing by IM The same procedure as in Example 1 was carried out.

[0075] 12. Loading into TEM and Analysis The sample for TEM observation using the reinforcing ring after thinning by IM was loaded into a TEM sample holder and placed in a TEM (JEOL Ltd., JEM-ARM200F). The film thickness in the upper part of the sample (coated body) that had been thinned by the argon ion beam was suitable for use as a sample for TEM observation, and it had an area that could provide a sufficient field of view, so it was possible to perform precise observation of the sample to be observed. [Explanation of symbols]

[0076] 11. Seat mesh 12. Sheet mesh on the ion gun side 13. Slots 14. Holes in the sheet mesh 15. Carbon thin film 16. Glue 17. Foundation 18.C-shaped reinforcement ring 19. Open end of C-shaped reinforcing ring 20. Sample (kneaded material) 21. Sample (applied body) 22.Applied body 23. Metal foil 24. Sample 25.Perforation 26.Design knife 31. Hardened sample 32. Fillers 41.Argon ion beam 61.TEM sample holder θ: The range of the incident angle when the argon ion beam is incident on the sample

Claims

1. providing a carbon thin film on a substrate; a step of adhering a sheet mesh onto the carbon thin film and fixing the sheet mesh on the base; Adhering a C-shaped reinforcing ring onto the sheet mesh; placing a sample in a hole in the sheet mesh and fixing the sample in the hole; scratching the carbon thin film around the outer periphery of the sheet mesh along the outer periphery of the sheet mesh; and a step of peeling off the sheet mesh from the base to obtain a hardened sample.

2. A method for preparing a sample for transmission electron microscope observation using a reinforcing ring, as described in claim 1, characterized in that the C-shaped reinforcing ring suppresses the occurrence of distortion in the sheet mesh during the process of placing a sample in a hole in the sheet mesh and fixing it in the hole, and during the process of peeling the sheet mesh off the base to obtain the hardened sample.

3. A method for preparing a sample for transmission electron microscope observation using a reinforcing ring as described in claim 1 or 2, characterized in that when loading the hardened sample into an ion milling device, the open end of the C-shaped reinforcing ring is placed opposite to the ion gun of the ion milling device.

4. 2. A method for preparing a sample for observation by a transmission electron microscope using a reinforcing ring according to claim 1, wherein the sample is a powder sample.

5. 2. A method for preparing a sample for transmission electron microscope observation using a reinforcing ring according to claim 1, wherein the sample is a sheet-shaped or flake-shaped sample.

6. 2. A method for preparing a sample for observation by a transmission electron microscope using a reinforcing ring according to claim 1, wherein the sample is a coated body in which sample powder is coated on a metal foil.

7. a step of fixing a coated body in which the sample powder is coated on a metal foil in the hole, and then a step of peeling the metal foil from the coated body; A method for preparing a sample for transmission electron microscope observation using a reinforcing ring, as described in claim 6, characterized in that, in the process of peeling off the metal foil, the C-shaped reinforcing ring suppresses the occurrence of distortion in the sheet mesh.

8. 2. A transmission electron microscope observation method, comprising: carrying out transmission electron microscope observation using a transmission electron microscope specimen prepared by the method for preparing a transmission electron microscope specimen using a reinforcing ring according to claim 1.

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