JP6974986B2 - A method for preparing an embedded resin sample for electron microscope observation and a mold used for it. - Google Patents

Description

The present invention relates to a method for preparing a sample for electron microscope observation using an ion beam processing apparatus, and more particularly to a method for preparing a powder-embedded resin sample.

The internal structure is analyzed by observing the cross section of the fine particles constituting the powder using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like.
Patent Document 1 describes a conventional method for observing a cross section of a fine particle with an electron microscope. FIG. 7A is a mold used for preparing a powder embedding resin sample. FIG. 7 (b) is a diagram showing an LL cross section of FIG. 7 (a). As shown in FIG. 7B, a mixture of a liquid resin and a powder is poured into the through hole C1 of the mold, and the resin C2 is waited for solidification. After the resin C2 has hardened, as shown in FIG. 7C, the resin C2 containing the powder C3 is taken out from the mold and cut along the dotted line C4. As shown in FIG. 7 (d), the embedded resin sample C5 cut from the resin C2 is sandwiched between the sample table D and the shielding plate S of the ion beam processing apparatus and mounted. Then, an ion beam is applied to the portion protruding from the shielding plate S to form the cross section C6.

JP 2013-167525

However, in the technique described in Patent Document 1, it is necessary to take out the resin in which the powder is embedded from the mold, select and cut the observation site, and sandwich it between the sample table of the ion beam processing apparatus and the shielding plate, which is small. Delicate processing work must be performed on the embedding resin sample, and the work requires skill. Further, when the surface of the embedded resin sample is processed by the ion beam processing apparatus, if the powder is sensitive to heat, damage such as melting or deformation due to the processing heat may occur on the sample.

In order to solve the above problems and achieve the object of the present invention, the present invention includes a step of preparing a plate having a bottomed hole on the surface and a step of preparing a plate.
A process of pouring a mixed solution of a sample and a resin into the hole from the opening of the hole and solidifying the mixture to prepare an embedded resin in the hole.
The process of cutting the plate holding the embedding resin in the hole and policy the plate fragment holding the embedding resin, and
A step of introducing the cross section of the plate into an ion beam processing apparatus and irradiating the embedding resin with an ion beam from the back surface direction of the plate to polish the cross section of the embedding resin.
It is characterized by being equipped with.

According to the present invention, since the processing work and the mounting work can be performed without taking out the embedded resin sample from the mold, the work can be performed without requiring skill. Further, since the heat generated in the embedded resin sample by the ion beam processing is dissipated through the mold, the damage due to the heat can be reduced.

It is a figure which showed the plate with a hole which concerns on this embodiment. It is a figure which showed the state which the mixture of resin and powder was poured into the hole of the plate which concerns on this embodiment. It is a figure which showed the cross section of the plate which concerns on this embodiment. It is a schematic diagram which rotationally grinds the observation sample of the electron microscope which concerns on this embodiment. It is a schematic diagram which a cross section of the observation sample of the electron microscope which concerns on this embodiment is processed by an ion beam. It is a figure which showed the state which the mixture of resin and powder was poured into the hole of the plate which concerns on this embodiment. It is a figure which showed the procedure of the sample preparation which concerns on the conventional example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1
(1) Preparation As shown in Fig. 1, a plate 1 provided with a hole 2 is prepared as a formwork.

For the plate 1, a silicon substrate cut out in a rectangular parallelepiped shape from a silicon wafer is used. The dimensions of the plate 1 are, for example, 1 mm in thickness × 4 mm in width × 8 mm in depth, and the hole 2 is a through hole having a diameter of about 2 mm.

As shown in FIG. 2, the plate 1 is closely fixed on the aluminum plate 3 (sealing body), and one opening of the hole 2 is closed. At that time, it is preferable to apply an adhesive to the lower surface of the plate 1 to bond and fix the plate 1. The aluminum plate 3 is thinner than the plate 1 and has a thickness of about 0.1 mm.

(2) A mixture of the embedded powder and the liquid resin is prepared, and the mixture is poured into the hole 2 of the plate 1 in a defoamed state. A heat-resistant resin is used. By leaving it for several hours until the resin is cured, the embedded resin 4 in which the powder is contained in the resin is produced. Inside the hole 2, the embedding resin 4 is in close contact with both the aluminum plate 3 and the inner side surface of the hole 2 and is cured.

(3) Cutting As shown in FIG. 2A, a confirmation line 5 is written on the upper surface A of the plate 1 at a position where the hole 2 is divided. By moving the cutting tool along the confirmation line 5, the plate 1 containing the embedding resin 4 and the aluminum plate 3 are cut and divided into two, and each divided piece is divided into two as shown in FIG. 2 (b). , The cross section of the embedding resin 4 is exposed. As the cutting tool, a tool capable of cutting metal such as a band saw or a low speed cutter is used. Since the plate 1 and the aluminum plate 3 are cut together with the embedding resin 4, the embedding resin 4 and the aluminum plate 3 can be kept in close contact with each other. The powder 6 is present in the cross section of the embedding resin 4 shown in FIG. Due to the difference in density from the resin, the powder 6 precipitates on the lower surface B side of the plate 1 when the entire resin is cured. Hereinafter, the plate 1 containing the embedding resin 4 and the aluminum plate 3 cut along the confirmation line 5 are referred to as an observation sample 7.

(4) Mechanical polishing As shown in FIG. 4, the cross section of the observation sample 7 is set toward the polishing surface 8 of the grinder so that the observation sample 7 is perpendicular to the polishing surface 8. Polishing is performed until the cross section of the observation sample 7 has irregularities of about 10 um or less. This is to prevent the appearance of streak-shaped processing marks caused by the influence of the unevenness on the cross section of the observation sample 7 when the cross section of the observation sample 7 is processed by the ion beam processing apparatus.

(5) Cross-section processing with an ion beam After the mechanical polishing is completed, the observation sample 7 is cross-sectioned with an ion beam processing apparatus. FIG. 5 is a schematic diagram of an ion beam processing apparatus. The ion beam processing apparatus has a function of irradiating the observation sample 7 with the ion beam 11 in the vacuum chamber to process the cross section of the observation sample 7. The ion beam 11 is generated from the ion gun 10 in the vacuum chamber and irradiates the observation sample 7 with an energy of about 2 to 6 keV.

As shown in FIG. 5, the observation sample 7 is attached to the sample holder 14 with the aluminum plate 3 facing the ion gun side, and is perpendicular to the optical axis 12 of the ion beam 11 generated from the ion gun 10. Be placed. Then, the shielding plate 13 is placed on the observation sample 7 so as to cover the portion other than the portion to be cut of the observation sample 7 from the ion beam. When the ion beam is irradiated from the aluminum plate 3 side toward the observation sample 7 and the shielding plate 13, the portion exposed from the shielding plate 13 of the observation sample 7 is machined together with the aluminum plate 3 to smooth the cross section. Is created.

The aluminum plate 3 facing the ion gun side is in close contact with the embedding resin 4, so that it efficiently absorbs the heat generated from the embedding resin 4 during cutting by the ion beam and transfers it to the shielding plate 13 to release it. The plate 1 serves to transfer the heat generated during cutting to the sample holder 14 and release it. Therefore, damage such as melting and deformation due to heat applied to the sample can be reduced. In addition to the aluminum plate, it is generally preferable to use a material that has high thermal conductivity and does not generate streak-like processing marks due to the difference in hardness of the constituent substances when treated with an ion beam, for example, amorphous or. A single crystal sheet can be used.

(6) Observation In the observation sample 7 subjected to the cross-sectional processing, the portion where the powder 6 is exposed is observed by a scanning electron microscope.

In the present invention, after cutting the embedding resin together with the plate, the cut plate can be held by hand for mechanical polishing work, setting on an ion beam processing device, and a scanning electron microscope, and taken out from the mold. Compared with the conventional method in which the embedding resin had to be handled as it is, the sample can be handled more easily, and the sample can be prepared without the need for skill.

Example 2
A modified example of the first embodiment will be described. FIG. 6 is a perspective view showing a plate 1 having a hole according to the present embodiment. Similar to the first embodiment, a silicon substrate cut out in a rectangular parallelepiped shape from a silicon wafer is used for the plate 1.

(1) Preparation As shown in FIG. 6 (b), a plate 1 having a bottomed hole 15 having a diameter of about 2 mm is prepared. The hole 15 of the plate 1 is formed by, for example, dropping a mixed solution of hydrogen fluoride and nitric acid onto the upper surface A of the plate 1 and melting the surface, but it may be formed by machining.

As shown in FIG. 6, the aluminum plate 3 (see FIG. 2) used in the first embodiment is excluded. Similar to the aluminum plate 3 of the first embodiment, the silicon substrate at the bottom of the hole 15 plays a role of absorbing heat generated from the embedded resin during cutting by an ion beam and transmitting it to a shielding plate to release it.

(2) Embedding In the same manner as in Example 1, an embedding resin 4 in which powder is contained in a resin is produced (FIG. 6). Inside the hole 15, the embedding resin 4 is in close contact with the inner side surface of the hole 15 and is cured.

(3) Cutting (cutting)
As shown in FIG. 6A, as a confirmation line 5, a notch 16 is made in the upper surface A of the plate 1 at a position where the hole 15 is divided. When the plate 1 containing the embedding resin 4 was placed in liquid nitrogen and divided into two pieces along the notch 16, each piece was embedded in each piece as shown in FIG. 6 (b). The cross section of the resin 4 is exposed.

Similar to Example 1, the powder 6 is present in the cross section of the embedding resin 4 shown in FIG. 6 (b). Due to the difference in density from the resin, the powder precipitates on the lower surface B side of the plate 1 when the entire resin is cured. Hereinafter, the cut plate 1 containing the embedding resin 4 is referred to as an observation sample 7.

(4) Mechanical polishing Similar to Example 1, the cross section of the observation sample 7 is mechanically polished.

In the above-mentioned (3) splitting, the embedding resin 4 may not be broken well and the embedding resin 4 may stick to one fragment of the divided plate 1 and greatly protrude from the split cross section of the plate 1. In this case, the embedding resin 4 in the portion that greatly protrudes from the fractured surface may be polished by mechanical polishing, and then mechanical polishing may be performed so that the fractured surface of the plate 1 and the embedding resin 4 are smooth. ..

(5) Cross-section processing with an ion beam After the mechanical polishing is completed, the observation sample 7 is cross-sectioned with an ion beam processing apparatus. The observation sample 7 is attached to the sample holder 14 with the lower surface B of the plate 1 facing the ion gun side, and is arranged perpendicular to the optical axis 12 of the ion beam 11 generated from the ion gun 10. Then, similarly to the first embodiment, the shielding plate 13 is placed on the observation sample 7 so as to cover the portion other than the portion to be cut of the observation sample 7 with the shielding plate 13. When the ion beam is irradiated from the lower surface B side of the plate 1 toward the observation sample 7 and the shielding plate 13, the portion exposed from the shielding plate 13 of the observation sample 7 is cut and smoothed together with the lower surface B of the plate 1. A modified cross section is produced.

The lower surface B facing the ion gun side is silicon having high thermal conductivity, and because it is in close contact with the embedding resin 4, it efficiently absorbs the heat generated from the embedding resin during cutting by the ion beam. It plays a role of transmitting to the shielding plate 13 and letting it escape. Therefore, damage such as melting and deformation due to heat applied to the sample can be reduced. In addition to silicon substrates, it is preferable to use a material that generally has high thermal conductivity and does not generate streak-like processing marks due to differences in the hardness of constituent substances during treatment with an ion beam, for example. Amorphous or single crystal plates can be used.

(6) Observation Similarly to Example 1, the observation sample 7 subjected to the cross-section processing is observed with a scanning electron microscope at a portion where the powder is exposed.

Plate 1, aluminum plate 3, embedding resin 4, powder 6, observation sample 7, polished surface 8, shielding plate 13

Claims (5)

The process of preparing a plate with a bottomed hole on the surface and
A process of pouring a mixed solution of a sample and a resin into the hole from the opening of the hole and solidifying the mixture to prepare an embedded resin in the hole.
A step of cutting the plate holding the embedding resin in the hole to prepare the plate fragment holding the embedding resin, and
A step of introducing the cross section of the plate into an ion beam processing apparatus and irradiating the embedding resin with an ion beam from the back surface direction of the plate to polish the cross section of the embedding resin.
A method for preparing an embedded resin sample for electron microscope observation. In the step of polishing the cross section of the embedded resin, the plate fragment introduced into the ion beam processing apparatus has a shielding plate on the back surface side of the plate that partially blocks the irradiation of the ion beam to the embedded resin. The method for producing an embedded resin sample for electron microscope observation according to claim 1, wherein the ion beam is arranged and irradiated over the shielding plate and the embedded resin. The method for producing an embedded resin sample for electron microscope observation according to claim 1 or 2, further comprising a step of providing a confirmation line or a notch indicating a cutting position on the plate. Any of claims 1 to 3, wherein the bottomed hole of the plate is formed by attaching a sealing body to one surface of a plate having a through hole and closing one opening of the through hole with the sealing body. A method for preparing an embedded resin sample for observation with an electron microscope described in Crab. The method for producing an embedded resin sample for electron microscope observation according to claim 4, wherein the sealed body is made of a metal material, a single crystal material, or an amorphous material.

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