JPH02204954A - Scanning type penetrative electron microscopic method - Google Patents

Abstract

PURPOSE:To obtain an image of as high in resolution as that of a conventional high-resolution penetrative electron microscopic image from a barrel of a penetrative electron microscope by scanning a specimen with a converged electron beam according to program, and sensing a scan image for the image drawn by the converged electron beam on the undersurface of the specimen. CONSTITUTION:An electron beam 10 generated from an electron gun 9 is contracted by an irradiative lens system 11 and irradiated onto a specimen 13. An image drawn under the specimen 13 upon penetration thereof is enlarged by a focusing lens system 14 to a magnification of ten thousand through one million and focused on a sensor 15. At this time, the specimen 13 is scanned with converged electrons by sending signals from a scanning signal generator 16 to a deflector 12, and lattice image can be obtained at any point in the specified region. This lattice image can be observed ocularly in the same manner as a conventional high-resolution penetrative electron microscopic image by performing high speed scanning with electron beam 10 any by observing on a fluorescent plate with an appropriate image remaining time. The scanning signal generator 16 is programmable, and the scanning region can be specified in any desired configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to electron microscopy, and more particularly to scanning transmission electron microscopy equipped with an analysis device suitable for microscopic analysis.

[Prior Art and Problems to be Solved by the Invention] Conventional scanning transmission electron microscopy has been carried out using a dedicated machine or a microscope equipped with an attached device to a transmission electron microscope. Compared to transmission electron microscopes, dedicated scanning transmission electron microscopes have a mechanism that is difficult to operate to accurately adjust the relationship between the crystal orientation and the incident electron beam, and it is difficult to easily obtain the high resolution of transmission electron microscopes. The disadvantage was that it was not possible to On the other hand, a transmission electron microscope equipped with an accessory device uses a tungsten or LaB filament electron gun, which results in insufficient brightness and poor vacuum (10-'Torr). machine), dedicated machine (
For example, the HB 501 model manufactured by V.C., UK) has problems such as the inability to analyze very small parts (the diameter of the focused electron beam is 0 and 5 nm). Furthermore, the objective lens pole pieces of transmission electron microscopes on board the ship are different for ultra-high resolution and analysis (scanning transmission), so they cannot be used at the same time.

In addition, in conventional technology, when driving a transmission electron microscope using a scanning transmission method, a method of drawing a transmission electron image, a secondary electron image, or an elemental image from an analyzer on a CRT or the like synchronized with a scanning signal is used. was used.

In the end, with such conventional techniques, it is difficult to perform analysis using a focused electron beam on the order of angstroms and to obtain the high resolution of a transmission electron microscope.

The purpose of this invention is '21! By scanning a focused electron beam obtained by an electron gun with a small virtual point light source such as a field-emission electron gun, the analysis position can be specified in the high-resolution image of a transmission electron microscope, and the angstrom of the target area can be determined. The goal is to enable order-accurate microscopic analysis.

In this invention, by using an electron beam with good coherence, it is possible to obtain a high-resolution image even when focused to about 11-degrees, and by scanning the focused electron beam over a sample, fluorescent screens, films, etc. It is now possible to use the mirror body of a transmission electron microscope to obtain an image on the detector with a resolution as high as that of a normal high-resolution transmission electron microscope.

[Means for Solving the Problems] The scanning transmission electron microscopy method of the present invention includes a generating means for generating an electron beam, a focusing means for focusing the electron beam generated by the generating means on a sample, and an enlarged sample image. In an electron microscope equipped with an enlargement means for projecting, a detection means for detecting a sample image, and a deflection means for deflecting electrons irradiated onto the sample, the deflection means causes a focused electron beam to be programmably scanned over the sample. , is characterized by obtaining a scanning image of the image formed by the focused electron beam on the lower surface of the sample.

[Operation] The scanning transmission electron microscopy method according to the present invention can be applied to microscopic electron diffraction, focused electron diffraction, energy dispersive X-ray analysis, wavelength dispersive X-ray analysis, electron energy loss spectroscopy, Auger electron spectroscopy, cathodoluminescence, etc. When performing analysis using a focused electron beam as a probe, the high resolution of a transmission electron microscope allows for accurate analysis of microscopic parts by specifying the analysis point.

[Example] Embodiments of the present invention will be described below based on the drawings.

First, an electron microscope used to implement this invention will be explained.

In FIG. 1, reference numeral 9 denotes an electron gun (for example, a field emission type electron gun), which generates a highly coherent and high-density electron beam.

The electron beam 10 generated from this electron gun 9 is directed through a focusing lens (
It is reduced to a size of about 1 nm by an irradiation lens system 11 formed by a front magnetic field (not shown) and an objective lens (not shown), and is irradiated onto a sample 13. The image transmitted through the sample 13 and formed below the sample 13 is magnified approximately 10,000 to 1,000,000 times by an imaging lens system 14 and is focused on a detector 15 . At this time, the imaging conditions for the above image are the same as those for obtaining a normal high-resolution transmission electron microscope image, and sample 13
Only the conditions of the irradiation lens system are different in order to focus the electron beam incident on the .

By using the electron gun 9 with high current density and high coherence, a high-resolution image can be observed within the focused electron beam.

The detector 15 may be an electrical or optical detector in addition to a fluorescent screen or film. 12 is a deflector, and 16 is a scanning signal generator.
By sending a signal to 12, it is possible to scan the sample 13 with focused electrons and obtain the above-mentioned lattice images for all points within the designated area. Scanning the electron beam 10 at high speed,
By observing with a fluorescent screen with an appropriate afterimage time, the lattice image can be observed with the naked eye in the same way as an ordinary high-resolution transmission electron microscope image. It can also be recorded on film.

The scanning signal generator 16 is programmable and can designate a scanning area in any shape.

For example, it is possible to skip any point within the scanning range, or the electron beam 10 can be stopped or the dwell time can be changed, and analysis points can be specified using a lattice image or the like. Furthermore, by adjusting the residence time, damage and contamination caused by irradiation of the electron beam 10 can be reduced or strengthened only in specific parts.

17 is an X-ray spectrometer that measures fluorescent X-rays generated from a designated analysis point, and 18 is an electron beam energy loss spectrometer that measures electrons that have passed through the sample 13 under the detector 15. These measurements are used to perform compositional analysis. Furthermore, elemental images can be obtained by synchronizing these with electron beam scanning.

Such an electron microscope is used as follows (see FIGS. 2 and 3).

When the focused electron beam 1 is irradiating a point 3 on the sample, the image formed on the imaging surface of the electron microscope under normal imaging conditions is 5 (second
(see figure (b)). The size of this image 5 is the diameter of the focused electron beam 1. By the deflector 12, the point 3 on the sample 13 is
When the irradiation position is scanned from point 4 to point 4, the image also moves correspondingly to point 6 on the image plane (see FIG. 26(b)). Figure 2(c)
represents the integral scan image 7.

The scanning by the deflector 12 is shown in FIGS. 3(a), (b), and (C).
Perform several routes or speeds as shown in .

The scan in Figure 3(a) is a one-way scan from the left to the right in the figure, and the scan in Figure 3(b) is a scan in which the scanning direction changes alternately. The scanning is a scanning in which a region 8 is not scanned by partially skipping.

By scanning with such a path or speed,
The integral scanning image 7 of the image plane, which is a superposition of these images, is
It is equivalent to a normal transmission electron microscope, and the amount of electron beam irradiation to a portion of the microscope can be controlled.

Then, an X-ray spectrometer 17, an electron beam energy loss spectrometer &
'(18) performs compositional analysis, etc. Also, by synchronizing these with the scanning of the electron beam, an elemental image is obtained.

[Effects of the Invention] As explained above, the scanning transmission electron microscopy method according to the present invention can be applied to microscopic electron diffraction, focused electron diffraction, energy dispersive X-ray analysis, wavelength dispersive X-ray analysis, and electron energy loss spectroscopy. When performing analysis using a focused electron beam as a probe, such as Auger electron spectroscopy, cathodoluminescence, etc., the high resolution of a transmission electron microscope allows for accurate analysis of microscopic areas.

Furthermore, it is also possible to partially control contamination and damage to the sample caused by the electron beam, which is a problem at this time.

[Brief explanation of the drawing]

The drawings are diagrams for explaining an embodiment of the scanning transmission electron microscope method of the present invention, and FIG. 1 is a schematic configuration diagram of the scanning transmission electron microscope, and FIGS. ) is an explanatory diagram of the relationship between the irradiation position of the electron beam and the imaging plane of the electron microscope, and FIGS. 3(a) and 3(b). (C) is an explanatory diagram of different scanning paths of the electron beam. 2... Deflector, 13... Sample, 4... Imaging lens system, 15... Detector, 6... Scanning signal generator, 17... X-ray spectrometer, 8...・Electron energy loss spectrometer.

Claims (1)

[Claims] A generating means for generating an electron beam, a focusing means for focusing the electron beam generated by the generating means on a sample, an enlarging means for projecting an enlarged sample image, and a detecting means for detecting the sample image. , an electron microscope equipped with a deflection means for deflecting electrons irradiated onto a sample, wherein the deflection means programmably scans a focused electron beam on the sample to create a scanned image of an image formed by the focused electron beam on the lower surface of the sample. Scanning transmission electron microscopy characterized by obtaining.