JPS5851452A - Analytic electron microscope - Google Patents

Abstract

PURPOSE:To perform the correction of the energy shifting automatically by modulating the strength of the energy analyzer such that the output electron energy will be constant irrespective of the variation of the irradiating position of the electron beam on the specimen. CONSTITUTION:The electron beam EB is irradiated on the specimen 2 in the focus lens system 1 to feed a portion of the passed e1ectron to the energy analyzer 3 and the electron having the specific energy is detected by the detector 5 to be fed to the display 8. While the output of the scan power source 7 for producing the saw-tooth signal is fed through the control circuit 11 to the excitation power source 10 for the analyzer 3 thus to modulate the strength of the analyzer 3 such that the output electron energy will be constant in relation to the scanning of the electron beam EB. Consequently even when the position of the electron beam EB on the specimen 2 is moved, it will never cause the shifting of the electron energy passing through the output slit 4 and the correction can be performed automatically.

Description

Detailed Description of the Invention The present invention is an analysis method that can automatically correct the energy shift related to the movement of the electron #M irradiation position with respect to the sample when obtaining an energy filter image in the scanning transmission electron microscope observation mode. This is related to electron microscopes.

Recent transmission electron microscopes have added many functions such as observation of scanning electron #4 imitation #iI images, X411 analysis, and energy analysis of consonant beams. Analyzing the energy of the electron beam transmitted through the sample using the device f
ζ is located below the imaging lens system lζ An energy analyzer is placed, and by sweeping this analyzer, it is possible to obtain the spectrum of energy loss due to the sample dζ of electrons transmitted through the sample.0 Figure 1 shows such an energy analyzer °. This diagram schematically shows an electron microscope equipped with an image forming lens system, and 1 indicates an imaging lens system, which actually includes an objective lens, a projection lens, an intermediate lens, etc. A thin film sample 2 is placed inside the objective lens or immediately therein, and a finely focused electron beam gB is introduced into the energy beam 6 by an electron beam irradiation system (not shown). This analyzer can be used, for example, by forming a uniform magnetic field (perpendicular to the plane of the paper) between two parallel magnetic pole plates, and separating the energy of electrons by using the difference in deflection force caused by this magnetic field. A sector radiation analyzer is used, and an exit slit 4 is placed immediately after the analyzer, and only electrons of a specific energy that pass through this are detected by a detector 5I. The output of this detector is supplied to a recorder or display device 1. The intensity of the analyzer is variable, and when swept over a certain range, the energy of the electrons taken out after passing through the slit 4 changes, and the energy spectrum is displayed. be done. Reference numerals 6m and 6b are electron beam deflection coils, which are placed on either side of the sample 2 and used to scan the electron beam over the sample.

By the way, let's take a look at this sickle device: the deflection coil 6a.

When the focused electrons @HB are scanned (or swept) one-dimensionally or two-dimensionally on the sample by 6b, the electron beams transmitted through each irradiation point of the sample are guided into the energy analyzer 5 through the imaging lens system, Since the energy that has been separated and passed through the exit slit 4 is detected by the detector 5 and sent to the display device, an energy filter image of the sample 2 in the scanning transmission mode can be obtained.However, by scanning, the dotted line gB As shown in Figure 2, as the position of the electron on the sample moves, the spot position on the imaging plane (the incident plane of the analyzer 6) moves, and the spot position moves in the analyzer as shown by the solid line and dotted line. Energy separation occurs, resulting in a shift in energy tζ of the electrons passing through the exit slit. As a result, the obtained scanning transmission image becomes a filter image with different energy depending on the location, and there is a drawback that the same energy filter image cannot be observed.

An object of the present invention is to provide an apparatus capable of observing an identical energy filter image without any energy shift. For this purpose, the configuration of the present invention scans or sweeps a focused electron beam with the sample, and the electron beam that has passed through the sample is passed through the imaging lens system to the energy analyzer 4.
The electrons that have passed through the output slit of the analyzer are detected, and the output is displayed on a display device.
Next, the intensity of the energy beam is modulated in synchronization with the scanning or sweeping of the electrons so that the energy of the emitted electrons remains constant regardless of changes in the irradiation position of the electron beam on the sample. Features and rb.

FIG. 2 is a block diagram of a device according to an embodiment of the present invention,
The same reference numerals as in FIG. 1 indicate the same components. 7 in the diagram
generate a sawtooth wave signal with a scanning power supply, and the deflection coils 6, .
6t) and the deflection coil of the display device 8. This display device is, for example, a negative 4III tube, and the signal from the detection@5 is supplied as the luminance signal through the video amplifier 9. Reference numeral 010 is an excitation power source for the analyzer 6, which is controlled by a control circuit 111ζ. A control signal synchronized with the scanning signal -ζ is sent to this control circuit from the scanning power source 7, and therefore the intensity of the analyzer f-5 is modulated in relation to the scanning of the electron beam gB. Then, the power source 10 is controlled to weaken the excitation of the analyzer for the electron beam,
As a result, electrons with the same energy are extracted through the slit 4 both in the case of the solid line and in the case of the dotted line.
In Figure 3 Heat ζ, if the electron beam shown by the dotted line is to the left of the solid line, the excitation intensity of the analyzer will be strong (it will be like this) If the control is carried out, the upper part of the display device 8 will display an energy-corrected, that is, a single-energy line profile or image.

In addition, in Toki Embodiment 1, when the magnification of the imaging lens 1 is varied, the displacement contribution of the electron beam on the incident surface 1 of the energy analyzer 6 differs, so the correction is appropriate according to the magnification i. It is preferable that the control circuit 11 be adjusted automatically or manually so as to be performed. Further, although a sector type energy analyzer is shown, it is not limited to this type, and it goes without saying that Ω reduction, electrostatic a1, etc. can also be used.

[Brief explanation of the drawing]

Figure 1 shows the main parts of a general analytical electron microscope, Figure 2
The figure is a block diagram showing one embodiment of the present invention, and FIG. 3 is an explanatory diagram of FIG. 2. 1: Imaging lens system, 2: Sample, 6: Energy source, 4: Output slit, 5: Detector, 6. ．． 6b: Deflection coil, 7: Scanning power supply, 8: Display device, 9: Multiplier,
10: Excitation power supply, 11: Control circuit. Patent applicant JEOL Ltd. Representative Tadao Kase

Claims (1)

[Claims] A means for irradiating the sample with a focused electron beam, a means for scanning or sweeping the electron beam over the sample, a lens system for forming an image of the electrons transmitted through the sample, and an energy analyzer for the electron beam placed below the lens system. , a detector for detecting electrons emitted from the analyzer, and a display means to which an output signal of the detector is supplied and synchronized with the scanning or sweeping of the electron beam. An analytical electron microscope characterized in that the scanning or sweep amount of the electrons is synchronously modulated so that the energy of the emitted electrons is constant regardless of changes in the irradiation position of the electron beam.