JP2024068714A - Sample observation method by scanning type electron microscope, preparation method for sample for observation by scanning type electron microscope, and management method for powder sample - Google Patents

Abstract

To provide a technique enabling objective scanning type electron microscope observation.SOLUTION: There is provided a sample observation method by a scanning type electron microscope that comprises the steps of: fixing a powder sample to a tape stuck on a sample table; sectioning the tape where the powder sample is fixed into a plurality of sections and marking in the plurality of sections respectively; and imaging a position at a predetermined distance away from the mark as an observation visual field by a scanning type electron microscope to obtain a plurality of images as many as the plurality of sections.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for observing a sample using a scanning electron microscope, a method for preparing a sample for observation using a scanning electron microscope, and a method for managing a powder sample.

To accommodate the trend towards smaller and lighter industrial products, there is a growing need to miniaturize raw materials as well. Examples include powders such as metal powders, ceramic powders, and resin powders, which are used in a variety of applications including powder metallurgy, injection molding, paints, pastes, and catalysts. Recently, there has been an increasing need for fine powders on the nanometer order known as nanoparticles, and powders with uniform particle size and grain size. The finer the powder, the more susceptible it is to deterioration due to oxidation, etc., so surface treatments may be applied.

For example, a scanning electron microscope (SEM) can be used to analyze such powders. SEM can grasp the particle size of fine powders ranging from millimeter-order powders to nanometer-order powders, confirm the granularity of powders with poor shape or generation of coarse particles, and detect coating peeling or abnormal precipitates in metal-coated powders. Furthermore, it can also investigate foreign matter mixed in from the outside. These are possible because SEMs can take images from low magnifications of several times to high magnifications of several hundred thousand times, but it is difficult to find the same field of view again, especially at high magnifications. In addition, at high magnifications, the observation is limited to a local area, so there is a problem that the measurer may find a field of view that is convenient for the measurer, for example, a field of view with few coarse particles even though coarse particles are generated in the powder, and determine that the powder has few coarse particles. If the same image as the image taken by the measurer can be taken in the laboratory, that is, if the images can be aligned, it becomes possible to analyze the powder in a way that is satisfactory to both parties.

For example, Patent Document 1 discloses a technique for forming a 3D reference mark by attaching it to a sample, and using the 3D reference mark to locate the position of an area of interest on the sample. Patent Document 2 discloses an optical observation device that sets a sample on a stage, moves it to a target position while observing it using external coordinates or continuous optical images, marks both sides of the target position to be observed/processed using a laser optical system arranged coaxially with the optical observation system, stores the optical image of the marked position together with the position coordinates in a storage medium, retrieves the stored data from an external FIB/SEM, and identifies the target position to be observed/processed from the laser mark.

JP 2014-006524 A Japanese Patent Application Laid-Open No. 11-329315

The object of the present invention is to provide a technology that enables objective scanning electron microscope observation.

The first aspect of the present invention is a method for producing a cellular membrane comprising the steps of:
Fixing the powder sample to a tape attached to a sample stage;
a step of dividing the tape on which the powder sample is fixed into a plurality of sections and marking each of the plurality of sections;
A method for observing a sample using a scanning electron microscope, comprising the steps of: imaging a position a predetermined distance away from the marking as an observation field of view using a scanning electron microscope, and obtaining a plurality of images corresponding to the number of the plurality of sections.

A second aspect of the present invention is a method for producing a composition comprising the steps of:
In the step of obtaining the plurality of images, the contrast value and brightness value of the scanning electron microscope are adjusted so as to approach the contrast of a reference image captured in advance, which is the method of observing a sample using a scanning electron microscope according to the first aspect described above.

A third aspect of the present invention is a method for producing a composition comprising the steps of:
In the method for observing a sample using a scanning electron microscope according to the second aspect described above, in the step of obtaining the plurality of images, the plurality of images are obtained using a scanning electron microscope different from the scanning electron microscope with which the reference image was captured.

A fourth aspect of the present invention is a method for producing a composition comprising the steps of:
The method further includes a step of imaging a position at a predetermined distance from the marking as an observation field by a first scanning electron microscope, and obtaining a plurality of reference images corresponding to the number of the plurality of sections;
This is a method of observing a sample using a scanning electron microscope as described in any one of the first to third aspects, in which, in the step of obtaining the multiple images, a second scanning electron microscope different from the first scanning electron microscope images the same observation field as the reference image, and obtains multiple images corresponding to the number of the multiple sections.

A fifth aspect of the present invention is a method for producing a composition comprising the steps of:
Fixing the powder sample to a tape attached to a sample stage;
a step of dividing the tape on which the powder sample is fixed into a plurality of sections and marking each of the plurality of sections.

A sixth aspect of the present invention is a method for producing a composition comprising the steps of:
Fixing the powder sample to a tape attached to a sample stage;
a step of dividing the tape on which the powder sample is fixed into a plurality of sections and marking each of the plurality of sections;
A step of imaging a position at a predetermined distance from the marking as an observation field by a scanning electron microscope to obtain a plurality of images corresponding to the number of the plurality of sections;
and a step of checking whether or not there is a defect in the powder sample from the plurality of images.

The present invention makes it possible to perform objective observations using a scanning electron microscope.

FIG. 1 is a flowchart showing an example of a sample observation method using a scanning electron microscope according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of an observation sample according to the first embodiment of the present invention. FIG. 3 is a reference image of section Z1 according to the first embodiment of the present invention. FIG. 4 shows an image of the same field of view as the reference image of section Z1 according to the first embodiment of the present invention. FIG. 5 is a reference image of section Z6 according to the second embodiment of the present invention. FIG. 6 shows an image of the same field of view as the reference image of section Z6 according to the second embodiment of the present invention.

Next, one embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope of the claims.

First Embodiment of the Present Invention
(1) Sample observation method using a scanning electron microscope (SEM) A sample observation method using a scanning electron microscope (SEM) according to the present embodiment will be described. Fig. 1 is a flow chart showing an example of a sample observation method using an SEM according to the present embodiment. As shown in Fig. 1, the sample observation method using an SEM according to the present embodiment includes, for example, a sample fixing step S101, a sample partitioning/marking step S102, a first imaging step S103, and a second imaging step S104.

(Sample fixing step S101)
The sample fixing step S101 is, for example, a step of fixing a powder sample to a tape 3 attached to a sample stage 2 shown in Fig. 2. Examples of the powder sample include metal powder, ceramic powder, resin powder, etc. In this embodiment, a case where a powder sample made of metal powder is used will be described.

It is preferable that the powder sample is free of segregation. The sample can be divided, for example, as described in JIS Z 8827-1 (Particle size analysis - Image analysis method - Part 1: Static image analysis method) and by referring to JIS Z 8816 (General rules for powder sample sampling method). This procedure prepares a powder sample free of segregation.

In SEM, the powder sample must be fixed to tape 3 because the image is taken in a vacuum state. Tape 3 is attached to sample stage 2 for installation on the SEM stage to fix the sample, so it is preferable that the tape has an adhesive surface on both sides. Examples of tape 3 with adhesive surfaces on both sides include double-sided tape, carbon tape, copper foil tape, aluminum foil tape, etc., but carbon tape, copper foil tape, or aluminum foil tape, which are conductive and heat-resistant, are preferable. Among them, carbon tape, which is mainly composed of light element carbon, is preferable when imaging an element mapping image obtained by detecting backscattered electron images or characteristic X-rays with EDS. Furthermore, carbon tape for SEM, which has fewer impurities, is more preferable among carbon tapes. Tape 3 is attached to the flat surface of sample stage 2, and the powder sample is fixed to the adhesive surface on the opposite side without any gaps. The sample that is not fixed to the adhesive surface of tape 3 is removed by blowing gas. Since fine powders are particularly prone to oxidation, it is recommended to use inert and inexpensive nitrogen gas.

(Sample compartmentalization/marking step S102)
The sample compartmentalization/marking step S102 is, for example, a step of dividing the tape 3 on which the powder sample is fixed into a plurality of compartments and marking each of the plurality of compartments. This step makes it possible to obtain an observation sample 1 as shown in FIG. 2. The number of the plurality of compartments and the shapes and sizes of the compartments are not particularly limited. In this embodiment, as shown in FIG. 2, a case will be described in which the tape 3 is divided into ten lattice-shaped compartments Z1 to Z10 and a mark 4 is applied to each of the compartments Z1 to Z10.

In the sample compartmentalization/marking step S102, it is preferable to physically and irreversibly mark the tape 3 attached to the sample stage 2 on which the powder sample is fixed, with grid-like lines, dividing the sample into multiple compartments. This prevents the multiple compartments from shifting or disappearing, making it possible to perform objective SEM observation. A cutter knife, razor, or the like can be used to mark such grid-like lines. When marking the grid-like lines, care should be taken not to allow the powder sample fixed to the tape 3 to fall off. The blade of the cutter knife, razor, or the like can be pressed vertically against the tape 3 on which the powder sample is fixed. The thickness of the grid-like lines may be any thickness that can be confirmed in an SEM image. The shape of the multiple compartments should be a square or rectangle, which can be easily created.

In the sample compartmentalization and marking step S102, for example, it is preferable to physically and irreversibly mark each of the multiple compartments. This prevents the mark 4 from shifting or disappearing, making it possible to perform objective SEM observation. Such marks 4 may be made with a sharp object such as a marking needle, the tip of tweezers, or an awl. A charged particle beam or laser may also be used. The mark 4 may be of a size that can be confirmed by SEM. For observations at a magnification of 1000 times or less, a marking needle, the tip of tweezers, or an awl may be used with a sharp object, and for observations at a magnification of more than 1000 times, a charged particle beam or laser may be used. When using a sharp object such as a marking needle, the tip of tweezers, or an awl, if the part that comes into contact with the sample is contaminated or has foreign matter attached, it may be impossible to distinguish it from an abnormal part or foreign matter in the SEM image, so it is preferable to check that there is no contamination or foreign matter on the sharp object such as the marking needle, the tip of tweezers, or an awl before making the mark 4. The mark 4 can be placed anywhere within the section, but when observing multiple fields of view, it is preferable to align the marks 4 in a similar place, for example, in the upper left corner of sections Z1 to Z10 as shown in Figure 2, so that it is easy to find the marks 4.

(First imaging step S103)
The first imaging process S103 is a process in which, for example, a first scanning electron microscope (SEM) is used to image a position a predetermined distance away from the marking (mark 4) as an observation field, and a plurality of reference images corresponding to the number of sections are obtained.

In the first imaging step S103, for example, the observation sample 1 obtained in the sample compartmentalization and marking step S102 is placed on the stage of the first SEM. To facilitate the observation operation, it is preferable to place the observation sample 1 on the stage of the first SEM in such a direction that the longitudinal direction of the tape 3 is parallel to the vertical direction of the SEM stage.

In the first imaging step S103, for example, the mark 4 on the observation sample 1 is placed in the field of view of the first SEM. If the magnification has been determined, the mark 4 on the observation sample 1 is placed in the field of view of the first SEM using that magnification. If the magnification has not been determined, a magnification suitable for the sample is determined before placing the mark 4 on the observation sample 1 in the field of view, and the mark 4 on the observation sample 1 is placed in the field of view of the first SEM at that magnification. The position of the mark 4 in the field of view is not particularly limited, and when observing multiple fields of view, it is preferable to place the mark 4 in a similar location so that it is easy to find, for example, if the mark 4 is placed in the upper left of a grid-like section, the position of the mark 4 should be on the left side of the field of view. The mark 4 can be confirmed by a secondary electron image, a backscattered electron image, or an element mapping image obtained by detecting characteristic X-rays with an energy dispersive X-ray detector (EDS). An element mapping image obtained by detecting characteristic X-rays with an EDS may be referred to as an EDS element mapping image hereinafter. In this embodiment, a case where a backscattered electron image is used will be described.

In the first imaging step S103, for example, the stage of the first SEM is moved a predetermined distance starting from the mark 4 to determine the observation field. In the case of grasping the particle size of the powder sample, checking the granularity of the powder sample with regard to the formation of defective shapes or coarse particles, or detecting coating peeling or abnormal precipitates in the case of metal-coated powder, the observation field is determined by moving the stage of the first SEM in an arbitrary direction so that the observation field is in an unbiased location. The arbitrary direction may be anywhere within the section, and the observation field may be determined by moving the stage of the first SEM in either the vertical or horizontal direction within a plane. The observation field may also be determined by moving the stage of the first SEM in an oblique direction.

In the first imaging step S103, for example, an image of the determined observation field is captured. There are three main methods for capturing images with an SEM: secondary electron image, backscattered electron image, and EDS element mapping image. Since an SEM can obtain images with a deeper focal depth even at higher magnifications than an optical microscope, all three methods, secondary electron image, backscattered electron image, and EDS element mapping image, are suitable for observing microscopic objects. In this embodiment, a case where a backscattered electron image is used will be described.

A backscattered electron image is a two-dimensional image obtained by detecting backscattered electrons emitted by elastic scattering when a sample is irradiated with a scanning electron beam using a backscattered electron detector. Backscattered electrons are generated from a depth of about 10 nm (0.01 μm) to 100 nm (0.1 μm) from the surface of the sample, and the higher the atomic number, the more backscattered electrons are emitted, resulting in a higher contrast. In other words, the elements contained in the field of view can be distinguished by the difference in contrast. Therefore, when using a backscattered electron image, it is important to adjust the image to distinguish elements by the difference in contrast. If the entire image is too bright or too dark, it becomes difficult to distinguish the elements contained. It is preferable to image the optimal observation field for distinguishing the elements contained in the observation field using a SEM control computer or SEM control panel that can adjust the contrast value and brightness value so that the elements contained in the sample can be distinguished. The contrast value and brightness value can be quantified by the SEM control computer in percentage and recorded as the contrast value and brightness value. Furthermore, for the reasons mentioned above, backscattered electron images are suitable for obtaining elemental information from powder samples with particle sizes of, for example, about 0.01 to 1 μm, and the sample observation method of this embodiment is particularly suitable for use with backscattered electron images.

In the first imaging step S103, for example, multiple reference images corresponding to the number of multiple sections are obtained. The SEM control computer not only adjusts the contrast value and brightness value of the SEM image, but can also save or call up the captured SEM image. The reference image is saved as an electronic file in the SEM control computer, or the reference image is printed on paper media via the SEM control computer. The SEM image of the observation field saved as an electronic file in the SEM control computer can be viewed on a monitor attached to the SEM control computer.

In the first imaging step S103, for example, after obtaining a number of reference images, the observation sample 1 is removed from the first SEM. At this time, since touching the powder sample can cause contamination, the observation sample is removed from the first SEM by holding the side of the sample stage 2. After removal from the first SEM, in the case of a powder sample that is easily oxidized, such as a fine powder, it is stored in a vacuum desiccator, a container filled with nitrogen gas or argon gas, a glove box, or the like to prevent it from coming into contact with oxygen. Samples that deliquesce, absorb moisture, hydrolyze, etc. due to moisture may be stored in a vacuum desiccator, a container filled with nitrogen gas or argon gas, or in a desiccator containing silica gel.

(Second imaging step S104)
The second imaging step S104 is, for example, a step of imaging the same observation field as the reference image by a second scanning electron microscope (SEM) different from the first scanning electron microscope (SEM) to obtain a plurality of images according to the number of sections. That is, it is a step of obtaining a plurality of images by another SEM different from the SEM with which the reference image was imaged. In this step, since a second SEM different from the first SEM is used, for example, even if the device and the person who measured are changed, objective SEM observation is possible. Note that care must be taken to prevent contamination of the powder sample during transportation, the powder sample from falling off, etc., and if a long interval has passed since the first imaging step S103 was performed, care must also be taken to prevent changes in the powder sample over time.

In the second imaging step S104, for example, the observation sample 1 is placed on the stage of the second SEM. To facilitate the observation operation, it is preferable to place the observation sample 1 on the stage of the second SEM in such a direction that the longitudinal direction of the tape 3 is parallel to the vertical direction of the SEM stage.

In the second imaging step S104, for example, the mark 4 on the observation sample 1 is placed in the field of view of the second SEM, similar to the first imaging step S103. The SEM image may be captured at the same magnification as the reference image using the method employed in the first imaging step S103.

In the second imaging step S104, for example, the stage of the second SEM is moved from the position of mark 4 to search for the same field of view as the reference image. By referring to the record of the movement direction of the stage of the first SEM in the first imaging step S103, it becomes easier to find the same field of view. When determining whether it is the same field of view, it is advisable to refer to characteristic shapes in multiple reference images while comparing them with the reference image, or in the case of foreign objects, to the shape of the foreign object. Note that the same field of view in this specification also includes cases where, for example, 90% or more of the area in the field of view is the same.

In the second imaging step S104, it is preferable to adjust the contrast and brightness values of the second SEM so that the contrast approaches that of the reference image (taken in advance) obtained in the first imaging step S103. Specifically, for example, the contrast and brightness values are adjusted in the SEM control computer or SEM control panel while comparing the image obtained in this step with the reference image so that the image has a similar contrast to that of the reference image. This makes it possible to fill in the gaps caused by differences in equipment conditions through image processing, making it possible to perform objective SEM observations.

In the second imaging step S104, for example, a plurality of images corresponding to the number of sections are obtained. The magnification does not vary much depending on the model of SEM, but if the imaging range differs from the reference image, the magnification of the second SEM may be changed. The acquired plurality of images are stored as electronic files in the SEM control computer, or printed on paper media via the SEM control computer. The SEM image of the observation field stored as an electronic file in the SEM control computer can be viewed on a monitor attached to the SEM control computer, but if the SEM manufacturer is different, the image may not be able to be called up using the SEM control software. If the SEM manufacturer is different, it is recommended to save the SEM image in an image file format that can be recognized by a general computer, such as JPEG format, TIFF format, PNG format, or BMP format.

In the second imaging step S104, for example, after obtaining a number of images, the observation sample 1 is removed from the second SEM. At that time, since touching the powder sample can cause contamination, the observation sample is removed from the second SEM by holding the side of the sample stage 2. After removal from the second SEM, in the case of a powder sample that is easily oxidized, such as a fine powder, it is stored in a vacuum desiccator, a container filled with nitrogen gas or argon gas, a glove box, or the like to prevent it from coming into contact with oxygen. Samples that deliquesce, absorb moisture, hydrolyze, etc. due to moisture may be stored in a vacuum desiccator, a container filled with nitrogen gas or argon gas, or in a desiccator containing silica gel.

(2) Effects of the Present Embodiment According to the present embodiment, one or more of the following effects can be obtained.

(a) Because SEM observes localized areas, it is possible to select areas far removed from the overall image, particularly at higher magnifications, and so there is a risk that the observer may take an image that is convenient for the observer, for example, an image of a field of view in which no coarse particles are present, even though coarse particles are present in the powder, and evaluate the powder as free of coarse particles. In contrast, in the sample observation method using SEM in this embodiment, the observation sample 1 is divided and the field of view is determined before observation, making it possible to perform objective SEM observations regardless of the observer.

(b) In the sample observation method using SEM of this embodiment, the tape 3 on which the powder sample is fixed is divided into a plurality of sections, and a mark is placed within each of the plurality of sections. For example, if there is only one marking, it becomes necessary to move the stage a large distance from the mark 4 when capturing a plurality of images. In this case (particularly when using an SEM in which the stage is moved manually), it becomes difficult to search for the same field of view as the reference image in the second imaging step S104. In contrast, in this embodiment, the distance by which the stage is moved from the mark 4 can be very small, making it easy to search for the same field of view as the reference image in the second imaging step S104.

(c) According to the sample observation method using SEM of this embodiment, even if the equipment or the person observing is changed, an image with the same contrast as the reference image can be obtained in the same field of view. Therefore, for example, SEM observation can be smoothly handed over to another tissue, etc.

<Other embodiments of the present invention>
Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, the second imaging step S104 may be omitted. In this case, the multiple reference images obtained in the first imaging step S103 may be interpreted as multiple images. Even in this case, as in the above-described embodiment, the partitioning and field of view determination are performed before observing the observation sample 1, making it possible to perform objective SEM observation regardless of the operator.

Also, for example, if a reference image captured in advance is prepared, the first imaging step S103 may be omitted. In this case, as in the above-described embodiment, differences caused by device conditions can be filled in by image processing, making it possible to perform objective SEM observation regardless of the operator. Also, in the second imaging step S104, it is not necessary to capture the same field of view as the reference image. In this case, too, differences caused by device conditions can be filled in by image processing, for example, by adjusting the contrast value and brightness value to approach the contrast of the reference image, making it possible to perform objective SEM observation regardless of the operator.

For example, in the above embodiment, the case where two types of SEMs, a first SEM and a second SEM, are used has been described, but only one type of SEM may be used. In other words, the same SEM may be used in the first imaging process S103 and the second imaging process S104. Due to changes in the electron beam over time, etc., even if the SEM settings are the same, images with the same contrast are not necessarily obtained. With this method, differences that arise due to the state of the device can be filled in by image processing, making it possible to perform objective SEM observations regardless of the person performing the measurement.

For example, the present invention can also be applied as a method for preparing a sample for observation with a scanning electron microscope. In this case, the first imaging step S103 and the second imaging step S104 may be omitted. Since the observation sample 1 is partitioned and the field of view is determined before the sample is observed, the use of this sample enables objective SEM observation regardless of the person performing the measurement.

The present invention can also be applied as a method for managing powder samples (e.g., metal powder). In this case, for example, after the second imaging step S104, a step of checking the presence or absence of defects in the powder sample (e.g., abnormal precipitates or coarse particles) from multiple images may be performed. According to this management method, the presence or absence of defects in the powder sample can be checked from multiple images that have been compartmentalized and have their fields of view determined before observation, making it possible to perform objective management without relying on the person performing the measurement.

Next, examples of the present invention will be described. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

Example 1
In order to check for defects such as coating anomalies or the presence of coarse particles for metal-coated powder (hereinafter referred to as the sample) in which the atomic number of the coated metal is greater than that of the base metal, images of the same field of view were taken by different operators using the same SEM. The SEM used was a JEOL JSM-7100F (field emission electron gun type, hereinafter referred to as SEM-1). Operator A prepared the sample and captured the reference image, and operator B captured an image of the same field of view as the reference image.

A piece of SEM carbon tape (manufactured by Nissin EM: tape width 12 mm) cut to a length of 24 mm was attached to a sample stage (manufactured by Oken Shoji: diameter 32 mm, made of aluminum). The sample, which had been reduced in size in accordance with JIS Z 8816, was fixed without any gaps to the adhesive part of the SEM carbon tape. The sample that was not fixed to the SEM carbon tape was blown away and removed using nitrogen gas.

Ten rectangular areas measuring 4 mm in length and 6 mm in width were created by pressing a clean, dirt-free, and foreign matter-free cutter blade against the SEM carbon tape perpendicularly to the tape, drawing grid lines at one location in the center of the length of the SEM carbon tape on which the sample was fixed, and four locations at 4 mm intervals in the direction perpendicular to the length. Of the ten rectangular areas, the top left was section Z1, sections Z2 to Z5 were located downward, the area to the right of section Z5 was section Z6, and sections Z7 to Z10 were located upward from section Z6 (see Figure 2). A marking needle with a clean, dirt-free and foreign matter-free tip was pressed against the top left part of each of sections Z1 to Z10 to make marks.

While holding the side of the sample stage on which the sample was fixed, the SEM carbon tape on which the sample was fixed was placed on the stage of the SEM-1 so that its longitudinal direction was parallel to the vertical direction of the SEM-1 stage. After inserting the SEM-1 stage into the sample chamber of the SEM-1, the sample chamber was left there until a vacuum state was reached that allowed SEM measurement.

After the sample chamber reached a vacuum state suitable for SEM measurement, the imaging magnification was set to 100x, the electron beam acceleration voltage to 5 kV, and the detector to a backscattered electron detector on the SEM-1 control computer, and the stage of the SEM-1 was moved using the stage movement dial on the SEM-1 control panel to bring the mark of section Z1 into the upper left of the field of view. The location of the mark was confirmed on the monitor attached to the SEM-1 control computer (hereinafter, the "monitor attached to the SEM-1 control computer" will be referred to as the "SEM-1 monitor"). The observation field was determined by rotating the SEM-1 stage once to the right using the stage left-right movement dial on the SEM-1 control panel. While watching the observation field displayed on the SEM-1 monitor attached to the SEM-1 control computer, the brightness was adjusted by turning the brightness adjustment dial and contrast adjustment dial on the SEM-1 control panel, and an SEM image of the observation field was captured. The captured SEM image of the observation field was saved in the computer controlling the SEM-1 and used as the reference image of section Z1 (Figure 3). As shown in Figure 3, the presence of coarse particles 5 was confirmed in the reference image of section Z1, and it was also found that there were granular abnormalities 6 that were different in shape from the other particles but had the same brightness. These were also used as reference when acquiring images of the same field of view, as described below. Furthermore, since there were no bright areas, it was also found that no abnormal deposits of the coating metal were present in section Z1. The same operation as above was carried out for sections Z2 to Z10, and 10 reference images were obtained.

After capturing the reference image, the vacuum state of the SEM-1 was released, the sample chamber of the SEM-1 was opened, and the sample stage was removed from the stage of the SEM-1. The sample stage with the removed sample fixed to it was stored in a container filled with nitrogen gas.

Operator B removed the sample stage, on which the sample had been fixed, from the container filled with nitrogen gas, and while holding the side of the sample stage on which the sample was fixed, placed it on the stage of SEM-1 so that the longitudinal direction of the SEM carbon tape on which the sample was fixed was parallel to the longitudinal direction of the SEM-1 stage. After inserting the SEM-1 stage into the sample chamber of SEM-1, the sample chamber was left to stand until a vacuum state was reached that allowed SEM measurement.

After the sample chamber reached a vacuum state suitable for SEM measurement, the imaging magnification was set to 100x, the electron beam acceleration voltage to 5 kV, and the detector to a backscattered electron detector using the SEM-1 control computer, and the stage of the SEM-1 was moved using the stage movement dial on the SEM-1 control panel to place the mark of section Z1 in the upper left of the field of view. The location of the mark was confirmed on the SEM-1 monitor. The stage movement dial on the SEM-1 control panel was rotated once in the direction of moving to the right. When this field of view was compared with the reference image of section Z1 (Figure 3) displayed on the SEM-1 monitor, it was found to be slightly off from the field of view of the reference image, so the left-right movement dial and the up-down movement dial were used as reference for the coarse particles 5 and granular abnormalities 6 in the reference image of section Z1. The brightness of the field of view was also different from that of the reference image, so the brightness adjustment dial and contrast adjustment dial on the SEM-1 control panel were adjusted to obtain an image of the same field of view as section Z1 shown in Figure 4. The same operations as above were performed for sections Z2 to Z10, and 10 images with the same field of view as the reference image were obtained.

After acquiring images of the same field of view, the vacuum state of the SEM-1 was released, the sample chamber of the SEM-1 was opened, and the sample stage was removed from the stage of the SEM-1. The sample stage with the removed sample fixed to it was stored in a container filled with nitrogen gas.

As shown in Figures 3 and 4, SEM images with similar contrast were obtained in the same field of view, even when the observer was different. In other words, it was confirmed that objective SEM observation is possible regardless of the observer.

Example 2
The image of section Z6 captured by observer A described in Example 1 was used as a reference image (FIG. 5), and observer C obtained an image of the same field of view using an SEM different from SEM-1. Observer C used a JSM-IT200 (thermal electron gun type, hereafter referred to as SEM-2) manufactured by JEOL Ltd. As shown in FIG. 5, coarse particles 5 and what appeared to be abnormal deposits 7 of the coated metal, which appeared brighter than the other particles, were observed in the reference image of section Z6.

Operator C removed the sample stage, on which the sample had been fixed, from the container filled with nitrogen gas, and while holding the side of the sample stage on which the sample was fixed, placed it on the stage of the SEM-2 so that the longitudinal direction of the SEM carbon tape on which the sample was fixed was parallel to the longitudinal direction of the SEM-2 stage. After inserting the SEM-2 stage into the sample chamber of the SEM-2, the sample chamber was left to stand until a vacuum state was reached that allowed for SEM measurement.

After the sample chamber reached a vacuum state suitable for SEM measurement, the imaging magnification was set to 100x, the electron beam acceleration voltage to 5 kV, and the detector to a backscattered electron detector on the SEM-2 control computer, and the SEM-2 stage was moved using the stage movement dial on the SEM-2 control panel to place the mark of section Z6 in the upper left of the field of view. The location of the mark was confirmed on the monitor attached to the SEM-2 control computer (hereinafter, the "monitor attached to the SEM-2 control computer" will be referred to as the "SEM-2 monitor"). The stage was rotated one turn to the right using the left-right movement dial on the SEM-2 control panel. When this field of view was compared with the reference image of section Z6 obtained in Example 1 (Figure 5) on the SEM-2 monitor, it was found to be misaligned with the field of view of the reference image of section Z6, so the left-right movement dial and the up-down movement dial were used to search for the same field of view as the reference image of section Z6, referring to the coarse particles 5 and abnormal deposits 7 of the coated metal in the reference image of section Z6. The brightness of the field of view was also different from the reference image of section Z6, so the brightness and contrast adjustment dials on the SEM-2 control panel were adjusted to obtain an image of the same field of view of section Z6 shown in Figure 6. Note that because an image of the same field of view could be obtained by the above operation, the magnification was not changed. The same operation as above was performed for the other sections, and 10 images of the same field of view as the reference image were obtained.

After acquiring images of the same field of view, the vacuum state of the SEM-2 was released, the sample chamber of the SEM-2 was opened, and the sample stage was removed from the stage of the SEM-2. The sample stage with the removed sample fixed to it was stored in a container filled with nitrogen gas.

As shown in Figures 5 and 6, SEM images with similar contrast were obtained in the same field of view, even when the equipment and person using the measurement were changed. In other words, it was confirmed that objective SEM observation is possible regardless of the equipment or person using the measurement.

In addition, comparing FIG. 3 and FIG. 5, FIG. 3 had relatively few coarse particles 5, and granular abnormalities 6 were observed. On the other hand, FIG. 5 had more coarse particles 5 than FIG. 3, and coated metal abnormal precipitates 7 were observed, but no granular abnormalities 6 were observed. If only FIG. 3 was provided, it may be determined that the sample had few coarse particles 5. On the other hand, if only FIG. 5 was provided, it may be determined that the sample had relatively many coarse particles 5. Also, if only FIG. 3 was provided, it may be determined that coated abnormal precipitates 7 were not included. On the other hand, if only FIG. 5 was provided, it may be determined that granular abnormalities 6 were not included. In this way, if the measurer determines the field of view after observing the sample, the subjective judgment of the measurer may affect the field of view, and a biased judgment such as that described above may be made. In contrast, in this embodiment, since the sectioning and field of view were performed before observing the sample, there was no room for the subjective judgment of the measurer, and it was confirmed that objective SEM observation was possible.

1 Observation sample 2 Sample stage 3 Tape 4 Mark 5 Coarse particle 6 Granular abnormality 7 Abnormal precipitate S101 Sample fixing step S102 Sample compartmentalization and marking step S103 First imaging step S104 Second imaging step

Claims (6)

Fixing the powder sample to a tape attached to a sample stage;
a step of dividing the tape on which the powder sample is fixed into a plurality of sections and marking each of the plurality of sections;
a step of imaging a position a predetermined distance away from the marking as an observation field using the scanning electron microscope, and obtaining a plurality of images corresponding to the number of the plurality of sections. The method for observing a sample using a scanning electron microscope according to claim 1, wherein in the step of obtaining the multiple images, the contrast value and brightness value of the scanning electron microscope are adjusted so as to approach the contrast of a reference image captured in advance. The method for observing a sample using a scanning electron microscope according to claim 2, wherein in the step of obtaining the plurality of images, the plurality of images are obtained using a scanning electron microscope other than the scanning electron microscope with which the reference image was captured. The method further includes a step of imaging a position at a predetermined distance from the marking as an observation field by a first scanning electron microscope, and obtaining a plurality of reference images corresponding to the number of the plurality of sections;
4. A method for observing a sample using a scanning electron microscope according to claim 1, wherein in the step of obtaining the plurality of images, a second scanning electron microscope different from the first scanning electron microscope images the same observation field as the reference image, and obtains a plurality of images corresponding to the number of the plurality of sections. Fixing the powder sample to a tape attached to a sample stage;
a step of dividing the tape on which the powder sample is fixed into a plurality of sections and marking each of the plurality of sections. Fixing the powder sample to a tape attached to a sample stage;
a step of dividing the tape on which the powder sample is fixed into a plurality of sections and marking each of the plurality of sections;
A step of imaging a position at a predetermined distance from the marking as an observation field by a scanning electron microscope to obtain a plurality of images corresponding to the number of the plurality of sections;
and a step of checking whether or not there is a defect in the powder sample from the plurality of images.