JP7396192B2 - Pedestal of sample stand for electron microscope and method for observing sample cross section - Google Patents

Description

The present invention relates to a pedestal for an electron microscope sample holder and a method for observing a cross section of a sample.

In electronic materials, the characteristics deteriorate due to the occurrence of abnormalities, so it is important to analyze the abnormalities. In this analysis, not only the surface of a sample (electronic material, etc.) is observed using an electron microscope, but also a cross-sectional observation is performed for the purpose of analyzing the inside of the sample, for example.

In order to perform cross-sectional observation, a sample to be analyzed is cross-sectionally processed using a microtome, a focused ion beam device (FIB), or the like, and processed into an analysis sample. Before carrying out cross-section processing, it is necessary to observe the sample surface in advance to identify abnormalities and to confirm the cross-section processing points. The cross-sectionally processed analysis sample is placed on a sample stage for a scanning electron microscope, and the cross-section is observed.

Incidentally, after cross-sectional observation of an analytical sample, additional processing may be performed and cross-sectional observation may be performed again. In this case, it is necessary to once remove the analysis sample fixed with carbon paste or the like from the sample stage, perform additional processing using a processing device, and then fix the analysis sample on the sample stage again. Attaching and removing the analysis sample from the sample stage not only reduces work efficiency, but also causes problems such as contamination of the cross section of the analysis sample and, in some cases, loss of the analysis sample.

Therefore, various types of pedestals have been proposed that allow the sample holder to be attached to a scanning electron microscope via the pedestal. Since the sample stage attached to the pedestal can be removed from the pedestal and attached to another processing device, there is no need to remove the analysis sample from the sample stage, and the efficiency of sample observation can be improved.

For example, Patent Document 1 proposes a pedestal that can share a sample holder with such a scanning electron microscope and other processing equipment. Patent Document 1 discloses a sample stand for an electron microscope that includes a recessed portion to which a sample stand for cross-section processing can be attached. According to such a specimen stage for an electron microscope, after performing cross-section processing on a sample fixed on the sample stage for cross-section processing in a cross-section processing device, the cross-section processing device can directly process the sample for cross-section processing without removing the cross-section processed sample. The entire stand can be loaded into an electron microscope.

Japanese Patent Application Publication No. 2014-146493

As mentioned above, various scanning electron microscope pedestals have been proposed that allow the sample holder to be used in common, allowing cross-sectional processing using a cross-sectional processing device such as a microtome or FIB, and cross-sectional observation using a scanning electron microscope.

Incidentally, lenses used in scanning electron microscopes (so-called electron lenses) include, for example, an out-lens type, an in-lens type, and a semi-in-lens (snorkel) type. The out-lens method is suitable for observing large samples and magnetic materials. Although the in-lens method is limited by sample size, it allows for high-resolution observation. The semi-in-lens method enables observation of large samples comparable to the out-lens method, and also enables observation with high resolution comparable to the in-lens method.

However, even with scanning electron microscopes, especially in the case of semi-in-lens and in-lens methods, the sample stage and pedestal must be repeatedly attached and detached during operations such as carrying out additional processing and performing cross-sectional observation again after the above-mentioned cross-sectional observation. During measurement, the observed image was sometimes distorted, making it impossible to maintain high resolution.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a technique for maintaining the high resolution of a scanning electron microscope when repeatedly observing the cross section of a sample using the scanning electron microscope.

The first aspect of the present invention is
A pedestal for supporting and fixing a sample holder on which a sample is placed to a sample mounting part of an electron microscope,
A cylindrical pedestal body,
a sample stand mounting hole provided on one surface of the pedestal main body and into which the sample stand can be attached;
a pedestal attachment hole provided on the other surface of the pedestal body for attaching the pedestal to a sample mounting section of the electron microscope;
The pedestal body is made of a non-magnetic and conductive material.
This is a pedestal for a sample stage for an electron microscope.

A second aspect of the present invention includes, in the first aspect,
a through hole provided on a side surface of the pedestal main body and penetrating from the side surface to the sample mount mounting hole as a screw hole;
By inserting a screw into the through hole, the sample stand mounted in the sample stand mounting hole can be fixed with a screw.

A third aspect of the present invention is, in the first or second aspect,
The sample stage includes a mounting part having a mounting surface on which the sample is placed, and a shaft part that is provided perpendicularly to the mounting part and can be inserted into the sample stage attachment hole.

A fourth aspect of the present invention is any one of the first to third aspects,
The pedestal body is made of at least one of aluminum, aluminum alloy, copper, and brass.

A fifth aspect of the present invention is any one of the first to fourth aspects,
The pedestal main body has a notch formed in the other surface and has an inclined surface that is inclined with respect to the other surface,
When the pedestal attachment hole provided on the other surface is used as a first pedestal attachment hole, a second pedestal attachment hole is provided on the inclined surface.

A sixth aspect of the present invention is any one of the first to fifth aspects,
The electron microscope is a semi-in-lens or in-lens scanning electron microscope.

The seventh aspect of the present invention is
A method for observing a cross section of a sample using an electron microscope, the method comprising:
placing a sample on a sample stage and performing cross-sectional processing on the sample to prepare an analysis sample;
a cylindrical pedestal body; a sample holder mounting hole provided on one surface of the pedestal body to which the sample holder can be mounted; a step of preparing a pedestal for an electron microscope sample holder, which includes a pedestal attachment hole for attaching the pedestal;
attaching the sample stand on which the analysis sample is mounted to the sample stand attachment hole of the pedestal and supporting and fixing it;
Observing a cross section of the analysis sample,
The pedestal body is made of a non-magnetic and conductive material.
This is a method for observing the cross section of a sample.

An eighth aspect of the present invention is, in the seventh aspect,
The pedestal is provided with a through hole as a screw hole on a side surface of the pedestal body that penetrates from the side surface to the sample stage mounting hole,
The sample stage is fixed by screwing a screw made of a non-magnetic and conductive substance into the through-hole.

A ninth aspect of the present invention is, in the seventh or eighth aspect,
The pedestal body is made of at least one of aluminum, aluminum alloy, copper, and brass.

A tenth aspect of the present invention is any one of the seventh to ninth aspects,
The electron microscope is a semi-in-lens or in-lens scanning electron microscope.

According to the present invention, the high resolution of the scanning electron microscope can be maintained when repeatedly observing the cross section of a sample using the scanning electron microscope.

FIG. 1 is a perspective view showing a schematic configuration of a pedestal according to an embodiment of the present invention. FIG. 2A is a top view of a pedestal according to an embodiment of the present invention. FIG. 2B is a side view of a pedestal according to an embodiment of the invention. FIG. 3 is a perspective view showing a schematic configuration of a pedestal according to another embodiment of the present invention. FIG. 4A is a bottom view of a pedestal according to another embodiment of the present invention. FIG. 4B is a side view of a pedestal according to another embodiment of the invention. FIG. 5 is a perspective view showing a schematic configuration of a sample stage mounted on a base.

<Inventor's knowledge>
The present inventor investigated the reason why the resolution of a scanning electron microscope cannot be maintained at a high level when the sample stage and pedestal are repeatedly used. As a result, it was found that this was due to metal powder adhering to the lens. For example, in the semi-in-lens method, the strongly excited lens magnetic field leaks to the sample side, so it was assumed that the image was distorted due to magnetized metal powder adhering to the lens.

However, since the sample stage is made of a non-magnetic material such as brass in order to place the sample on it, it was confirmed that the metal powder did not originate from the sample stage. Therefore, the inventor further investigated the origin of the metal powder. As a result, it was found that the metal powder was derived from the plating layer applied to the surface of the pedestal. For the pedestal, the sample is not in direct contact with the sample, and a certain level of strength is required to prevent the sample holder mounting hole from deforming when the sample holder is repeatedly attached, so the surface is plated with, for example, nickel. . Generally, when attaching a sample stand made of aluminum to a nickel-plated pedestal, the sample holder, which has lower strength than the pedestal, is likely to wear out easily, and it is thought that metal powder originating from the sample holder will increase. However, according to the inventor's research, if the sample stand is repeatedly attached to the pedestal, not only the sample stand but also the plating layer will wear out, producing magnetic metal powder such as nickel, which will adhere to the lens. I understand.

Based on this, the present inventor investigated constructing the pedestal with a non-magnetic and conductive material, and found that even when the sample holder is repeatedly attached, magnetic metal powder is generated. It was discovered that the high resolution of scanning electron microscopy can be maintained because it does not. The present invention has been made based on these findings.

<One embodiment of the present invention>
Hereinafter, one embodiment of the present invention will be described using the drawings. In the following, first, a sample stand attached to a pedestal will be described, and then a pedestal and a method for observing a cross section of a sample using the pedestal will be described. FIG. 1 is a perspective view showing a schematic configuration of a pedestal according to an embodiment of the present invention. FIG. 2A is a top view of a pedestal according to an embodiment of the present invention, when the pedestal is viewed from above in FIG. 1. FIG. 2B is a side view of a pedestal according to an embodiment of the invention. FIG. 5 is a perspective view showing a schematic configuration of a sample stage mounted on a base.

(sample stand)
The sample stage mounted on the base of this embodiment is, for example, a stage having a structure as shown in FIG. 5 (so-called pin stub). Specifically, the sample stage 20 includes a mounting section 21 having a mounting surface on which a sample is placed, and a shaft section 22 provided perpendicularly to the mounting section 21. The mounting section 21 has a flat mounting surface (upper surface in FIG. 5) on which a sample or an analysis sample obtained by subjecting the sample to cross-section processing can be mounted. A shaft portion 22 is provided perpendicularly to the mounting portion 21 on a surface of the mounting portion 21 opposite to the mounting surface. The shaft portion 22 is provided at the center of the mounting portion 21 .

(pedestal)
The pedestal of this embodiment is for introducing a sample holder on which a sample is placed into the measurement section of an electron microscope, and is configured so that it can support and fix the sample holder and can be attached to the sample mounting section of the measurement section. Ru. Specifically, as shown in FIGS. 1, 2A, and 2B, the pedestal 10 includes a pedestal main body 11, a sample mount mounting hole 12 provided on one surface 11a of the pedestal main body 11, and a sample mount mounting hole 12 provided on the other side of the pedestal main body 11. and a pedestal attachment hole 13 provided in the surface 11b. Hereinafter, one surface 11a will also be referred to as sample stage surface 11a, and the other surface 11b will also be referred to as pedestal surface 11b.

The base body 11 has a cylindrical shape. As described above, the sample stage 20 is made of a non-magnetic and conductive material so as not to generate magnetic metal powder when the sample stage 20 is repeatedly attached. Such a material is not particularly limited, but is preferably at least one of aluminum, aluminum alloy, copper, and brass.

The pedestal main body 11 can support and fix the sample holder 20 by attaching the sample holder 20 to the sample holder attachment hole 12 . The shape of the sample stage attachment hole 12 is not particularly limited as long as the sample stage 20 can be fitted therein. Preferably, the shape and size have a small fitting gap into which the shaft portion 22 of the sample stage 20 can be inserted and fixed.

The pedestal main body 11 can be attached to a sample mounting section in a measurement section of an electron microscope through a pedestal attachment hole 13. For example, the pedestal main body 11 can be fixed by screwing the pedestal attachment hole 13 into the convex screw portion of the sample mounting part. In addition, in this embodiment, although the sample stage attachment hole 12 and the pedestal attachment hole 13 are connected, they do not need to be connected and may be provided separately.

Further, in the pedestal main body 11, the sample pedestal surface 11a and the pedestal surface 11b are preferably parallel and each surface is flat. According to such a pedestal main body 11, the sample can be placed horizontally without tilting.

It is preferable that a through hole 14 is provided in the side surface of the pedestal body 11 as a screw hole that penetrates from the side surface to the sample stage attachment hole 12. By inserting a screw into the through hole 14 and pressing the tip of the screw against the shaft portion 22 of the sample stand 20 inserted through the sample stand attachment hole 12, the sample stand 20 can be reliably fixed to the stand main body 11. .

The material of the screw used for tightening is preferably a non-magnetic and electrically conductive material, such as brass and titanium. For example, by constructing screws from brass, it is possible to suppress the wear and tear of the screws when they are repeatedly tightened, and even if wear does occur, the metal powder does not have magnetism, which improves the resolution of cross-sectional observation using an electron microscope. There is no risk of deterioration. Further, it is more preferable that the material of the screw is the same as the material of the base body 11. For example, if the pedestal main body 11 is made of brass, brass screws may be used. By constructing the screw and the pedestal main body 11 from the same material, wear and tear on the screw or the pedestal main body 11 due to differences in hardness can be suppressed.

(Cross-sectional observation method)
Next, a method for observing the cross section of a sample using the above-mentioned pedestal will be explained.

First, a sample to be observed is prepared. This sample is placed on a sample stage 20 shown in FIG. 5, and cut with a cross-section processing device such as a microtome or a focused ion beam device. For example, in a dual beam focused ion beam device, the shaft portion 22 of the sample stage 20 is inserted into a hole in a pedestal for cross-section processing provided in the device and fixed with a set screw or the like. Then, the sample is cut using a focused ion beam. As a result, an analysis sample with an exposed cross section is obtained.

Subsequently, the sample stand 20 on which the analysis sample is placed is attached to the pedestal 10. Specifically, after inserting the shaft portion 22 of the sample stage 20 into the sample stage mounting hole 12 of the sample stage 20, a screw is inserted through the through hole 14, and the tip of the screw is pushed into the shaft portion 22 of the sample stage 20. By applying this, the sample stage 20 is fixed to the pedestal 10.

Subsequently, the pedestal 10 with the sample holder 20 fixed thereon is introduced into the measurement section of the scanning electron microscope and attached to the sample mounting section. For example, the pedestal 10 is fixed to the sample mount by screwing the pedestal attachment hole 13 of the pedestal 10 into the convex screw portion of the sample mount.

Next, the cross section of the analysis sample is observed using a scanning electron microscope. As a result of the observation, if it is necessary to further process the cross section of the analysis sample, it is preferable to remove the sample stage 20 from the pedestal 10 and insert it into the cross section processing apparatus. Thereafter, the analysis sample is again loaded into the scanning electron microscope and observed using the procedure described above.

In this embodiment, the pedestal main body 11 is made of a non-magnetic and electrically conductive material, so even if the sample holder 20 is repeatedly attached to the pedestal 10, the wear and tear caused by the attachment may cause damage. Generation of magnetic powder can be prevented. Therefore, even if the scanning electron microscope is a semi-in-lens type or an in-lens type, a decrease in resolution that may occur when the pedestal 10 is repeatedly used can be suppressed, and measurement accuracy can be maintained at a high level.

In addition, when performing additional processing on the sample, it is preferable to remove the sample stage 20 from the pedestal 10 and perform the additional processing on the sample. Thereafter, it is preferable to load the sample into a scanning electron microscope and observe the cross section according to the procedure described above.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the gist of the present invention.

In the above-described embodiment, a case has been described in which the surface 11b (pedestal surface 11b) of the pedestal main body 11 on which the pedestal attachment hole 13 is provided is uniformly flat, but the present invention is not limited to this. For example, the pedestal 10 may be configured as shown in FIGS. 3, 4A, and 4B. FIG. 3 is a perspective view showing a schematic configuration of a pedestal according to another embodiment of the present invention. FIG. 4A shows a bottom view of the pedestal, and FIG. 4B shows a side view of the pedestal. In addition, in FIG. 3, FIG. 4A, and FIG. 4B, the same code|symbol is attached|subjected to the same or corresponding part as FIG. 1, FIG. 2A, and FIG. 2B.

As shown in FIGS. 3, 4A, and 4B, the pedestal main body 11 has a notch formed on the other surface 11b (pedestal surface 11b) side where the pedestal attachment hole 13 is provided, and is inclined with respect to the pedestal surface 11b. When the pedestal mounting hole 13 provided in the pedestal surface 11b is the first pedestal mounting hole 13a, it is preferable that the slanted surface 15 has a second pedestal mounting hole 13b.

By providing the inclined surface 15 in the pedestal main body 11 and providing the second pedestal attachment hole 13b in the inclined surface 15, it is possible to attach the sample holder 20 in an inclined state with respect to the pedestal 10, and it is possible to attach different samples. It can be observed from any angle. In FIG. 3, the angle of the inclined surface is 45°, but the angle is not particularly limited and can be changed as appropriate.

Hereinafter, the present invention will be explained based on more detailed examples, but the present invention is not limited to these examples.

(Example 1)
First, a pin stub having a structure as shown in FIG. 5 was prepared as a sample stage. Further, as a pedestal, a pedestal made of aluminum and having the structure shown in FIG. 1 was prepared.

Subsequently, the sample was placed on the mounting surface of the sample stage, and its cross section was processed using a focused ion beam device (FIB). This exposed the cross section of the sample and obtained an analysis sample. The device used for cross-section processing was a dual beam device (“Quanta200 3D” manufactured by Japan FI Co., Ltd.).

Subsequently, the sample stand on which the analysis sample was placed was supported and fixed to the stand by fitting the shaft portion into the sample stand attachment hole of the stand and inserting a screw into the insertion hole. Then, the pedestal on which the sample holder was fixed was attached to the sample mounting part of the measurement part of a field emission scanning electron microscope (FE-SEM, "S-4700" manufactured by Hitachi, Ltd.). Thereafter, the cross section of the analysis sample was observed using FE-SEM. At this time, since the FE-SEM is of a semi-in-lens type, cross-sectional observation was performed by leaking the lens magnetic field to the analysis sample side.

In this example, the above-described cross-sectional processing of the sample, attachment of the sample stand to the pedestal, and cross-sectional observation were repeatedly performed, and it was confirmed that high resolution could be obtained in all cross-sectional observations.

(Comparative example 1)
In Comparative Example 1, cross-sectional observations were repeated in the same manner as in Example 1, except that the pedestal used was changed to one in which the surface of the pedestal main body was plated with Ni. Note that the fixing method on the pedestal is not a method of inserting a screw into the through hole of the present invention and pressing the tip of the screw against the shaft of the sample stage, but rather a method in which the inner diameter of the sample stage mounting hole is outside the axis of the specimen stage. The diameter of the specimen is slightly smaller than the diameter of the specimen, and the difference between the inner diameter and the outer diameter is absorbed by a plurality of slits cut across the sample mounting hole in the upper part of the pedestal body.

However, in Comparative Example 1, when the pedestal was used repeatedly, it was confirmed that the observed image was distorted and high resolution could not be obtained when the pedestal was used more than about 30 times. When we investigated the cause of this, we found that the Ni plating layer was abraded due to contact between the sample stand and the pedestal, producing metal powder, which became magnetized when the lens magnetic field leaked to the analysis sample side and adhered to the lens. I found out that it was because of this.

As explained above, by forming the pedestal body from a non-magnetic and conductive material so that the pedestal does not contain any magnetic material, cross-sectional observation is possible even when the pedestal is used repeatedly. can maintain high resolution.

10 Pedestal 11 Pedestal main body 11a Sample stage surface 11b Pedestal surface 12 Sample stage mounting hole 13 Pedestal mounting hole 13a First pedestal mounting hole 13b Second pedestal mounting hole 14 Through hole 20 Sample stage 21 Mounting part 22 Shaft part

Claims (9)

A pedestal for supporting and fixing a sample holder on which a sample is placed to a sample mounting part of an electron microscope,
A cylindrical pedestal body,
a sample stand mounting hole provided on one surface of the pedestal main body and into which the sample stand can be attached;
a pedestal attachment hole provided on the other surface of the pedestal body for attaching the pedestal to a sample mounting section of the electron microscope;
The pedestal main body is made of a non-magnetic and conductive material ,
The pedestal main body has a notch formed in the other surface and has an inclined surface that is inclined with respect to the other surface,
When the pedestal attachment hole provided on the other surface is a first pedestal attachment hole, a second pedestal attachment hole is provided on the inclined surface;
Pedestal of sample stage for electron microscope. a through hole provided on a side surface of the pedestal main body and penetrating from the side surface to the sample mount mounting hole as a screw hole;
configured to be able to fix the sample stand attached to the sample stand attachment hole with a screw by inserting a screw into the through hole;
A pedestal for an electron microscope sample holder according to claim 1. The sample stage includes a mounting part having a mounting surface on which the sample is placed, and a shaft part that is provided perpendicularly to the mounting part and can be inserted into the sample stage mounting hole.
A pedestal for an electron microscope sample holder according to claim 1 or 2. The pedestal body is formed from at least one of aluminum, aluminum alloy, copper, and brass.
A pedestal for an electron microscope sample holder according to any one of claims 1 to 3. The electron microscope is a semi-in-lens or in-lens scanning electron microscope,
A pedestal for an electron microscope sample holder according to any one of claims 1 to 4 . A method for observing a cross section of a sample using an electron microscope, the method comprising:
placing a sample on a sample stage and performing cross-sectional processing on the sample to prepare an analysis sample;
a cylindrical pedestal body; a sample holder mounting hole provided on one surface of the pedestal body to which the sample holder can be mounted; a step of preparing a pedestal for an electron microscope sample holder, which includes a pedestal attachment hole for attaching the pedestal;
attaching the sample stand on which the analysis sample is mounted to the sample stand attachment hole of the pedestal and supporting and fixing it;
Observing a cross section of the analysis sample,
The pedestal body is made of a non-magnetic and conductive material.
How to observe a cross section of a sample. The pedestal is provided with a through hole as a screw hole on a side surface of the pedestal body that penetrates from the side surface to the sample stage mounting hole,
fixing the sample stage with a screw by inserting a screw made of a non-magnetic and conductive substance into the through hole;
The method for observing a cross section of a sample according to claim 6 . The pedestal body is formed from at least one of aluminum, aluminum alloy, copper, and brass.
The method for observing a cross section of a sample according to claim 6 or 7 . The electron microscope is a semi-in-lens or in-lens scanning electron microscope,
The method for observing a cross section of a sample according to any one of claims 6 to 8 .

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