JPS61250952A - Electron microscope - Google Patents

Abstract

PURPOSE:To obtain an energy filter having high resolution by performing two-dimensional scanning of an image formed at the incident position of energy analyzer through deflection means arranged at the position of electron beam diffraction image in focus lens system. CONSTITUTION:An electron beam 1 transmitted through a sample 2 is passed through lenses 3-6 and to project an electronic microscopic image onto a screen 7. While an energy analyzer 13 is provided through an iris 14 to detect a selected electrons through a detector 16 and feed to a cathode ray tube 12. While X and Y deflectors 8X, 8Y are arranged at the positions in the lens system to be formed with electron beam diffraction image thus to feed saw-tooth X, Y scanning signals from scanning signal generating circuit 9 to the deflectors 8X, 8Y as well as the cathode ray tube 12. Since an energy filter image can be obtained without scanning the sample 2 by means of the focused electron beam, the sample 2 is never contaminated and the resolution is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electron microscope capable of obtaining an energy filter image of a sample.

[Conventional technology] An energy analyzer is attached to an analytical electron microscope,
An energy filter image of the sample is obtained by selectively detecting only 'Fl''f- having a specific energy among the electron beams that have passed through the sample.

Among the devices for obtaining such energy filter images, the first type of device scans the sample surface two-dimensionally with a narrowly focused electron beam, and the electrons that have passed through the sample along with this scanning are The beam is guided to an energy analyzer placed after the imaging system, and electrons with a specific energy selected by the energy analyzer are detected.
The detection signal is introduced into a cathode ray tube which is scanned in synchronization with the scanning of the electron beam.

The second type of device is one in which an omega-type analyzer, for example, is provided in the imaging lens system, and an energy loss image is obtained based on electrons of a specific energy in a transmission electron image mode.

Problems to be Solved by the Invention] In the first type of apparatus described above, since the electron beam probe must be scanned over the sample, the sample is heavily contaminated and a high-quality image cannot be observed.

In addition, when trying to obtain a low-magnification energy filter image, the deflection angle of the electron beam increases, so the angle of the electron beam incident on the energy analyzer changes greatly with scanning, and as a result, the angle of the electron beam incident on the energy analyzer changes significantly. The energy and energy of the extracted electrons fluctuate, and the energy resolution of the obtained image deteriorates.

Furthermore, in the latter type of device, an energy filter field is inserted into the imaging lens system, which causes distortion in the transmitted image.

An object of the present invention is to solve these conventional drawbacks and provide an electron microscope that can obtain an energy filter image with high energy resolution and no distortion without contaminating the sample.

[Means for Solving the Problems] In order to achieve such objects, the present invention provides an electron beam irradiation system for irradiating a sample with a focused electron beam, and an electron beam irradiation system for irradiating a sample with a focused electron beam. An imaging lens system for forming an image of a sample; an energy analyzer placed after the imaging lens system for selecting only electron beams with a specific energy; An electron @microscope equipped with a detector for detection, an electron beam deflection means disposed at a position of an electron beam diffraction image formed by the imaging lens system, and the energy analyzer in the electron beam deflection means. means for supplying a scanning signal for two-dimensionally scanning the electron microscope M image formed at the position of the entrance slit of the sample, and displaying an energy filter image of the sample based on the output signal of the detector. It is characterized by having a means for

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

FIG. 1 shows an example of an apparatus for carrying out the present invention. In the figure, 1 is an electron beam that is focused with good parallelism by a focusing lens system not shown. is irradiated. The electron m1 transmitted through each point of the sample 2 is passed through the objective lens 3. Objective mini lens 4° intermediate lens 5. An electron microscope image of the sample 2 is projected onto a display screen 7 by a projection lens 6 . Reference numerals 8x and 8y are X and Yl direction devices arranged at positions where electron beam diffraction images are formed between the objective mini-lens 4 and the intermediate lens 5. X and Y deflector 8x,
8y are connected to amplifiers 10x and 1 from the scanning signal generating circuit 9, respectively.
The X and Y scan signals are provided through 0y, respectively. The scanning signals from the scanning signal generation circuit 9 are sent to amplifiers 11X,
11'l/ to the X and Y deflection coils 12x, 12y of the cathode ray tube 12. 13 is an energy analyzer, 14.15 is an energy analyzer 1
3 entrance and exit apertures. 16 is a detector, and the output signal of the detector 16 is sent to the cathode ray tube 12 via an amplifier 17.
is sent to grid 12q.

In such a configuration, when the lenses 3, 4, and 5°6 are excited, electron microscope images AI, A2, and A3 are formed by the lenses 3, 4, and 5, respectively, and the image A3 is projected onto the screen γ by the projection lens. The final image A4 is formed.

Moreover, diffraction patterns 111[)1, D2, D3, and D4 are also formed between each lens. Therefore, the scanning signal generation circuit 9
Therefore, if #li tooth-shaped X and Y scanning signals as shown in Fig. 2 (a) and (b) are generated, the electron beam transmitted through the sample 2 will be deflected as shown by the dotted line in the figure. , the electron microscope image moves as shown by A4- on the screen 7, and the image A4 moves two-dimensionally during one cycle of the Y-direction scanning signal. Therefore, if the display screen 7 is removed from the optical axis so that the transmitted electrons can be guided to the entrance slit 14, electrons corresponding to each part of the image A4 will be incident on the energy analyzer 13 as a result of the above scanning. Among the electrons incident on the energy analyzer 13, only the electrons having a specific energy are emitted through the exit slit 15.
and is detected by the detector 16. Since the output signal of the detector 16 is sent to the grid 12q of the cathode ray tube 12,
The cathode ray tube 12 displays an energy filter image of the sample.

The present invention is not limited to the embodiments described above, and can be modified in many ways.

For example, in the above embodiment, the electron beam deflector was arranged at the position of the diffraction image formed between the objective mini-lens and the intermediate lens, but the position of the diffraction image formed at other positions Alternatively, a deflector may be placed.

[Effects of the Invention] As is clear from the above explanation, according to the electron microscope based on the present invention, since an energy analyzer is not inserted into the imaging lens system, an image without distortion can be obtained. In the present invention, since an energy filter image is obtained without scanning the sample with a focused electron beam, there is no contamination of the sample, and
Since electrons can always be guided to the energy analyzer at the same incident angle as the electron microscope image is scanned, energy resolution can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention.
FIG. 3 is a diagram for illustrating a Y scanning signal and a Y scanning signal. 1: Electron beam 2: Sample 3: Objective lens 4: Objective mini lens 5: Intermediate lens 6: Projection lens 7: Display screen 8
x, 8y: Deflector 9: Scanning signal generation circuit 10x, 1
oy, 11x. 11y, 17: Amplifier 12: Cathode ray tube. 13: Energy analyzer 14: Entry slit 15: Output slit 16: Detector

Claims (1)

[Claims] An electron beam irradiation system for irradiating a sample with a focused electron beam, an imaging lens system for forming an image of the sample based on the electron beam transmitted through the sample, and a subsequent stage of the imaging lens system. In an electron microscope, the imaging lens system is equipped with an energy analyzer for selecting only electron beams of a specific energy, and a detector for detecting the electrons selected by the energy analyzer. an electron beam deflection means disposed at the position of the electron diffraction image thus formed; and a means for two-dimensionally scanning the electron microscope image formed at the entrance slit of the energy analyzer on the electron beam deflection means. means for providing a scanning signal of;
An electron microscope characterized by comprising: means for displaying an energy filter image of the sample based on the output signal of the detector.