WO2015023025A1 - Method for producing transmission electron microscopy specimen using tripod polishing and focused ion beams - Google Patents

Abstract

The present invention relates to a method for producing a transmission electron microscopy specimen. The method for producing a specimen, according to the present invention, produces a transmission electron microscopy specimen by polishing a bulk specimen into a wedge shape, using a focused ion beam to finely etch the front and rear surface of at least one area of the polished specimen, and cleaning the finely etched specimen. The present invention enables a transmission electron microscopy specimen to be produced in a stable manner and reduces the amount of time required for production.

Description

Method of fabricating transmission electron microscope specimen using tripod polishing and focused ion beam

The present invention relates to a method for manufacturing a transmission electron microscope specimen, and more particularly, to a method for manufacturing a transmission electron microscope specimen for producing a specimen using tripod ploshing and a focused ion beam (focused ion beam).

Transmittance Electron Microscopy (TEM), although the principle of operation may be similar to that of commonly used optical microscopes, it is possible to transmit the specimen through an electron beam that is accelerated by applying a voltage instead of the light source and the light source lens. It is a microscope used by applying an electron lens to adjust the magnification.

When an electron beam is incident on a material, various phenomena occur due to the interaction between the specimen and the electron, and the transmission electron microscope uses electrons transmitted through a thin portion of the specimen. In other words, if the accelerated electrons smaller than the wavelength of the material to be observed are transmitted through the medium, the difference in the intensity of the electron beam that can be transmitted is generated according to the degree of crystal plane or defect, and the transmitted beam intensity difference is changed from the fluorescent screen to the contrast. Appear.

In order to effectively analyze a specific material using such a transmission electron microscope, a technique for producing a very thin specimen of 100 nm or less for a transmission electron microscope is very important. In a transmission electron microscope, the thinner the specimen, the higher the image quality. It is essential to process the sample thinly.

However, due to the accuracy of polishing and the difficulty in handling fragile materials, it takes a lot of time to produce a specimen for use in a transmission electron microscope, and it is also difficult to stably manufacture the specimen.

Therefore, there is a need for a method for improving the stability of specimen fabrication for transmission electron microscopy and reducing the time required for specimen fabrication as a whole.

Accordingly, it is an object of the present invention to provide a method for producing a transmission electron microscope specimen that can stably produce a specimen for use in a transmission electron microscope while reducing the time required for production.

In the method for fabricating a transmission electron microscope specimen according to the present invention for achieving the above object, the step of polishing a bulk specimen in the form of a wedge (wedge), using a focused ion beam on the front and back of at least one region of the polished specimen Etching fine, and cleaning the finely etched specimen to produce a transmission electron microscope specimen.

In addition, the transmission electron microscope sample manufacturing method according to the present invention for achieving the above object, manufacturing a sandwich specimen, polishing the sandwich specimen in the form of a wedge (wedge), at least one region in the polished specimen And finely etching the front and rear surfaces of the sample using a focused ion beam, and cleaning the finely etched specimen through an ion beam to produce a transmission electron microscope specimen.

And, in order to achieve the above object, the present invention provides a transmission electron microscope specimen prepared by the manufacturing method.

According to the present invention, the transmission electron microscope specimen can be stably manufactured by combining the microscopic visual and washing processes in the wedge polishing process in the specimen fabrication process using the tripod polishing and the specimen fabrication process using the focused ion beam, and multi-location Specimen production is also possible. It also eliminates ion milling in conventional tripod polishing, surface protection, peripheral machining, bottom cutting, probe welding, micro bridge separation, extraction, sample fixation, and probe cutting in conventional focused ion beams. This can shorten the time required.

1 is a flow chart provided in the description of the specimen manufacturing method according to an embodiment of the present invention,

2 shows an example of a tripod polisher,

3 is a reference to the description of the method for giving a wedge by adjusting the angle using a tripod polisher,

4 is a diagram referred to to explain the case given an angle to a Pyrex stub;

5 is a view referred to to explain the color seen in the optical microscope according to the silicon thickness,

6 is a view showing when the specimen is mounted on a copper grid,

7A to 7E are views referred to for description of the process of the microscopic vision using the focused ion beam,

8 is a view showing an image after fine etching using a focused ion beam,

9 shows an image of a transmission electron microscope for a specimen,

10 is a flow chart provided in the description of the specimen manufacturing method according to another embodiment of the present invention, and

11 is a view referred to for the description of the sandwich specimen.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

1 is a flow chart provided in the description of the method for manufacturing a transmission electron microscope specimen according to an embodiment of the present invention.

Referring to Figure 1, the transmission electron microscope specimen manufacturing method according to an embodiment of the present invention, wedge (S100), fine etching using a focused ion beam (S110), cleaning using a focused ion beam (S120) process It includes, and the completed specimen may be subjected to specimen analysis via a transmission electron microscope (S130).

Referring to each step process shown in Figure 1 as follows. First, bulk specimens for the object to be analyzed are prepared, and wedge polishing is performed by applying wedges to the prepared bulk specimens using tripod polishing (S100). Basically, bulk specimens can be prepared only by cutting the sample to be analyzed. However, if you want to see the interface of the thin film specimens in particular, it is necessary to bond the two surfaces to make the specimen like a sandwich.

Applying the wedge in tripod polishing to the bulk specimen may include first side polishing and second side polishing.

The first surface polishing or the bottom polishing process is necessary when polishing the bulk specimen, since it is difficult to accurately detect the surface to be viewed on the transmission electron microscope when the operation is performed while the bottom surface is not flat.

The first surface polishing process can be polished by fixing the bulk specimen to the Pyrex stub with an adhesive, and then inserting the bulk specimen onto the Pyrex stub and then inserting and polishing the tripod polisher.

The first surface polishing process is a process for making the base flat, so that it is not necessary to apply a wedge. Using a diamond lapping film on the polishing wheel, polishing was performed in the order of 30 μm → 15 μm → 3 μm → 1 μm → 0.5 μm, and a syton in the form of 0.6 μm silicon dioxide (SiO ₂ ) powder Finish with polishing with polishing cloth.

When the bottom surface becomes flat through the first surface polishing, the second surface polishing process involves attaching the flat bottom surface and then applying a wedge. In this process, the diamond lapping film and the syton are worked in the same order as the first surface polishing.

2 illustrates an example of a tripod polisher, which includes a frame 220 constituting a body, three micrometers 210 disposed on the upper surface of the frame 220 at 120 ° intervals, and a lower portion of the frame 220. And a plurality of support pieces 230 which are formed in and whose length is changed by the micrometer 210. The L-shaped bracket 240 is installed over the side and bottom of the frame 220, and the Pyrex stub 250 is mounted to the bent portion of the bracket 240. At this time, the part contacting the bottom surface 270 is a Pyrex stub 250 and the support piece 230.

The support piece 230 is leveled with the Pyrex stub 250 while the micrometer 210 is rotated counterclockwise (up) or clockwise (down).

After attaching the specimen 260 to the Pyrex stub 250, as shown in Figure 3, to prepare the tripod polishing by turning the micrometer 210 in the clockwise direction to give a wedge, the polishing process Can be performed.

When polishing is finished, the wedge of the specimen is formed, as shown in FIG. Specimen thickness in the edge region where wedges are formed is 1 μm to 2 μm. The specimen thickness checking method can be calculated using the wedge angle β and the distance L between the Pyrex stub 50, as shown in FIG. 3, and is confirmed while polishing with an optical microscope or the like. As shown, the fringe by thickness can be confirmed using reference data.

After the polishing process is finished, as shown in FIG. 6, after bonding the specimen 310 to the copper grid 310 cut in half using an adhesive, preparing for fabricating a multiple specimen using a focused ion beam, which is the next process. do.

Next, a fine etching process using a focused ion beam (FIB) is performed on the polished specimen (S110). In the general polishing process, the ion milling process is performed, but in the method for fabricating a specimen according to the present invention, since the fine etching process using the focused ion beam is performed, the ion milling process may be omitted. The focused ion beam apparatus scans a very thin focused ion beam onto the material surface to process the material surface. The smaller the thickness of the wedge polished specimen, the smaller the thickness to be finely etched by the focused ion beam, thereby reducing the overall time required to fabricate the specimen.

7A to 7E are views referred to for describing a process of fine etching using a focused ion beam.

7A to 7E illustrate an example of a window displayed on a display unit during a fine etching process using a focused ion beam. The left window 320 is a scanning electron microscope window, which allows a user to observe a specimen while using a focused ion beam. It's a window. The middle window 330 is a window for the ion beam and displays a task to be performed by the user. The right window 340 is a window displaying the setting and related information on the etching process through the ion beam, and may set the width (x), the thickness (y), the penetration depth (z) and the like.

7A is a screen for finding a reference point of a transmission electron microscope and an ion window, and FIGS. 7B and 7C are screens of a first fine milling process. 7D and 7E are screens of a second fine milling process.

Referring to this screen, the front and back surfaces of the wedge polished specimen are locally etched by a focused ion beam. Specifically, the polished specimen is mounted on the sample holder of the focused ion beam apparatus, and the front and rear portions of the specimen are etched by scanning the ion beam to the upper surface of the polished specimen. At this time, the width x may be set to about 6 μm, the thickness y to about 2 μm, and the penetration depth z may be about 2 μm, and the current density of the focused ion beam may be about 20 to 30 mA (Pico ampere). It is possible to finely etch the specimen by making it very small. These figures may vary depending on which sample the specimen is manufactured. Through this method, the front surface is finely etched and the back surface is etched repeatedly, thereby producing multiple specimens.

When the fine etching process is completed, a cleaning process is performed (S120). The cleaning process uses the same gallium (Ga) ions as the fine etching, but only the cleaning is performed by weakening the voltage and current values differently from the fine etching process. .

After the fine etching process and the cleaning process using the focused ion beam is finished, the transmission electron microscope specimen is manufactured, the analysis of the specimen using the transmission electron microscope may be performed (S130).

By this process, the transmission electron microscope specimen can be produced quickly and stably. For example, using the specimen manufacturing method according to the present invention, it is possible to produce about 10 specimens in 3 hours. In addition, the use of automated processes can improve yield.

The difference between the specimen fabrication method according to the present invention and the specimen fabrication method using a general focused ion beam is that, in the specimen fabrication method according to the present invention, surface protection, peripheral processing, bottom cutting, probe welding, micro-bridge separation in a general focused ion beam process A total of eight processes, extraction, sample holding and probe cutting, are omitted, and the elimination of the lift-out process for bulk specimens can reduce overall manufacturing time and ensure stability. In addition, even if the conventional process proceeds from the fine etching using the focused ion beam, because the thickness of the specimen is thick, the fine etching process takes a very long time and the efficiency decreases.

In addition, the difference from the specimen manufacturing method using a conventional tripod polisher is that there is no ion milling (ion milling) process. Since ion milling is a process of etching the specimen by irradiating the Ar ⁺ ion beam, the specimen may be damaged during ion milling, and it may not be able to precisely etch a portion to be accurately analyzed.

FIG. 8 is a view showing an image after fine etching using a focused ion beam, and FIG. 9 is a view showing an image of a transmission electron microscope for a specimen.

Since the specimen fabrication method according to the present invention minimizes the thickness of the specimen itself through a tripod polishing process (1 to 2 μm), it is required for the entire process, in contrast to the conventional focused ion beam or tripod polishing method. The time taken can be reduced by five times or more. In addition, multi-location specimens may be fabricated using a focused ion beam.

10 is a flow chart provided in the description of the specimen manufacturing method according to another embodiment of the present invention.

In the present embodiment, the processes of steps S360 to S390 for wedge polishing, fine etching using the focused ion beam, cleaning using the focused ion beam, and specimen analysis are the same as those described in the above-described embodiment.

In this embodiment, however, sandwich specimens 401 and 403 as shown in FIG. 11 are used. In the case of sandwich specimens 401 and 403, the deposited surfaces face each other and are bonded by applying epoxy 410 therebetween. Epoxy 410 is easy to analyze the specimen because it is transparent when observed by a transmission electron microscope, as well as the effect of preventing damage to the deposited surface as well as adhesion. The polishing and subsequent steps are the same as for the bulk specimen described above.

On the other hand, the transmission electron microscope specimen manufacturing method according to the invention is not limited to the configuration and method of the embodiments described as described above, the embodiments are all or all of the embodiments so that various modifications can be made Some may be optionally combined.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

The invention can be used to fabricate specimens for transmission electron microscopy using tripod ploshing and focused ion beams.

Claims (13)

1. Polishing the bulk specimen in the form of a wedge;

   Fine etching the front and back surfaces of at least one region of the polished specimen using a focused ion beam; And

   A method of manufacturing a transmission electron microscope specimen comprising cleaning the finely etched specimen to produce a specimen for transmission electron microscope.
2. The method of claim 1,

   The polishing may include: making the first surface flat, and polishing the second surface into a wedge shape using the first surface as a bottom surface.
3. The method of claim 1,

   The polishing process is a transmission electron microscope specimen manufacturing method, characterized in that performed using a tripod polisher.
4. The method of claim 1,

   In the fine etching step, the width x is 5 μm to 7 μm, the thickness y is 1 μm to 3 μm, the penetration depth z is 1 μm to 3 μm, and the current density of the focused ion beam is 20 μs to Method of producing a transmission electron microscope specimen, characterized in that set to 30㎀.
5. The method of claim 1,

   The thickness of the polished specimen is a transmission electron microscope specimen, characterized in that 1㎛ 2㎛.
6. The method of claim 1,

   The cleaning is a transmission electron microscope specimen manufacturing method, characterized in that the process of washing by lowering the voltage and current value than the process of fine etching.
7. Specimens for transmission electron microscope prepared by the method of any one of claims 1 to 6.
8. Preparing a sandwich specimen;

   Polishing the sandwich specimen in the form of a wedge;

   Fine etching the front and back surfaces of at least one region of the polished specimen using a focused ion beam; And

   A method of manufacturing a transmission electron microscope specimen comprising cleaning the finely etched specimen to produce a specimen for transmission electron microscope.
9. The method of claim 8,

   The sandwich specimen is a transmission electron microscope specimen manufacturing method characterized in that the adhesive is produced by bonding so that the surfaces deposited using epoxy to face each other.
10. The method of claim 8,

    In the fine etching step, in the fine etching step, the width x is 5 μm to 7 μm, the thickness y is 1 μm to 3 μm, the penetration depth z is 1 μm to 3 μm, the focused ion beam The transmission electron microscope specimen manufacturing method, characterized in that the current density of 20 to 30 kHz.
11. The method of claim 8,

    The polishing process is a transmission electron microscope specimen manufacturing method, characterized in that performed using a tripod polisher.
12. The method of claim 8,

    The cleaning process is a transmission electron microscope specimen manufacturing method, characterized in that the process of cleaning by lowering the voltage and current value than the fine etching process.
13. Specimen for a transmission electron microscope produced by the manufacturing method of any one of claims 8 to 12.

Images