JP7174203B2 - Transmission electron microscope (TEM) with photoelectron microscope (PEEM) capability - Google Patents

Description

The present invention relates to a method of using the capabilities of a PEEM, a device that illuminates the surface of a bulk material and produces a magnified image of the emitted photoelectrons, as an adjunct to a TEM.

The spatial resolution of PEEM is generally low, remaining at several tens of nm. (Non-Patent Document 1)

Therefore, the applicants filed a patent application for reduction of objective lens aberration, increase in detected signal amount, and correction of aberration in order to improve the spatial resolution of PEEM. (Patent Document 1)

A top-class TEM with lens aberration correction has reached atomic resolution, but samples are limited to thin films, and bulk materials cannot be observed. (Non-Patent Document 2)

Therefore, a STEM (scanning transmission electron microscope) with a built-in SEM (scanning electron microscope) function that can observe bulk samples has been developed, but only reports of catalyst particles of 3 to 5 nm are available, and atomic resolution cannot be obtained. (Non-Patent Document 3, Figure 6)

Application number: 2018-228545 (step number: 0012-0015)

Photoelectron Microscope Photoelectron Microscope, Toyohiko Kinoshita, Yuichi Haruyama, Synchrotron, Vol. 13, No. 4 (2000) p. 292-297.

Non-Patent Document 2: Limit of Resolution of Electron Microscope, Daisuke Shindo, Kenji Hiraga, Materia Vol. 35, No. 11 (1996), 1230-1234.

Atomic resolution image observation by secondary electrons, Hiromi Inada, Mitsuru Konno, Keiji Tamura, Kuniyasu Nakamura, (2012.02) Hitachi Review, p. 29 Figure 6

In the PEEM disclosed in Patent Literature 1, in order to exhibit high resolution performance, it is necessary to individually take measures against the installation environment such as vibration, noise, and room temperature.

As mentioned above, the TEM has the above installation environment measures, and has the atomic resolution of thin film materials. Atomic resolution cannot be obtained.

A PEEM is attached to the TEM instead of the SEM. for that purpose,

In order to integrate the PEEM function into the TEM, the sample 1 must be exposed to the light 2 .

Since the sample 1 of the TEM is at ground potential, even if the sample 1 is exposed to the light 2, the photoelectrons generated have low energy, and the acceleration voltage necessary for the action of the lens system cannot be obtained. It must be placed at potential 3.

The PEEM light source 6 is placed in the TEM camera chamber 5 to illuminate the sample. When the camera room is not equipped, the flange 7 for inserting the accessory device and the diaphragm 8 of the lens are used.

A sample holder used for PEEM Figure 2 shows a structure that can hold both a thin film and a bulk. Therefore, both ends of the sample are made of an insulating material 4 .

By constructing the PEEM not as a dedicated device but as an accessory device of the TEM as shown in FIG. 1b, it is possible to achieve atomic resolution even in the PEEM with a TEM that has taken atomic resolution measures for the installation environment.

This enables atomic resolution observation of thin film samples and bulk samples with a single device.

2. By using the sample holder FIG. 2, the TEM image and the PEEM image can be switched or simultaneously observed without exchanging the sample 1, so it is possible to prevent the shift of the field of view and the deterioration of the sample due to the sample exchange.

Overall view of PEEM as an accessory function of TEM according to the present invention a Overall view of TEM b Figure with PEEM function added Overall view of the sample holder and enlarged view of the tip Form of sample a Thin film part and bulk part formed for the same use b Separately arranged thin film sample and bulk sample a Path of light irradiation and photoemission when used as PEEM b Path of electron beam irradiation and transmission when used as TEM

In FIG. 1, the TEM can be used as a PEEM while maintaining the TEM function, so that the atomic resolution observation can be facilitated by using the TEM lens barrel that has taken measures for the installation environment as it is.

The sample 1 can be insulated from the holder portion of the sample holder shown in FIG. 2 by the material 4 and placed at a high potential, so that the photoelectrons emitted from the sample can obtain the acceleration voltage necessary for receiving the lens action.

When the sample 1 is irradiated with the light 2 from the light source portion 6 in the camera chamber 5, the flange 7, or the aperture 8 of the lens, photoelectrons 9 are emitted and the PEEM functions.

Photoelectrons 9 emitted from the sample 1 by applying light 2 in FIG. are observed and photographed in the camera room 5.

In the case of the TEM, as shown in FIG. 4b, an electron beam 16 passes through a thin film portion 20 of the sample, is focused and magnified by the objective lens 10, is magnified by the imaging lenses 11, 12, and 13, and is magnified by the fluorescent screen 14. It is converted into a visible image, observed, and photographed in the camera room 5 .

As shown in FIG. 3a, the same sample is etched to form a thin film portion and a bulk portion, and the sample is moved to observe each. Alternatively, as shown in FIG. is observed by placing a thin film sample 22 and moving the sample in the same manner.

1. Sample 2. light3. high voltage section4. Insulation material5. camera room6. light source section 7 . lens barrel flange 8 . lens aperture9. Photoelectronics 10 . objective lens 11 . Imaging lens 1
12. Imaging lens 2
13. Imaging lens 3
14. fluorescent plate 15 . electron gun section 16 . electron beam 17 . Focusing lens 1
18. Converging lens 2
19. Converging lens 3
20. thin film portion 21 . bulk portion 22 . Thin film sample 23 . bulk sample24. Accelerating voltage part

Claims (2)

a lens aperture 8 below the sample 1 for directing the light 2 onto the downwardly mounted sample 1; A TEM characterized in that a light irradiation function is provided in the TEM. The TEM according to claim 1 is characterized by adding a PEEM function that enables atomic resolution observation of both thin film samples and bulk samples simultaneously or alternately .

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