JPS6220229A - Television electron microscope for analysis - Google Patents

Abstract

PURPOSE:To enable an analyzing point to be set easily while observing the image of a sample, by providing a television cameral, video signal amplifier, and CRT and letting it possible to change the amplification factor of the video signal amplifier in synchronization with the change of the beam size. CONSTITUTION:The television image is displayed on a CRT10 after passing through an amplifier 12 having a low amplification factor in the image observing mode of an electron microscope 19. Then the electron microscope 19 is changed into the spot mode, and a switch 11 is simultaneously turned to the side of an amplifier 13 having a high amplification factor. This operation is automatically performed through a system controller 15 and a synchronous signal generator 16. As a result, a bright spot image can become visible on the CRT10, and the analyzing point can be easily set.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to improvements in analysis equipment for transmission electron microscopes.

[Background of the invention]

Recently, there has been an increasing demand for analysis of microscopic parts of samples (for example, elemental analysis) using transmission electron microscopes. The principle of this analysis method is to detect characteristic X-rays generated by atoms excited by electron beam irradiation and fix the elements contained therein. Therefore, in order to analyze minute parts, , it is necessary to narrow down the electron beam applied to the sample.

However, as is well known, a transmission electron microscope is a device that irradiates an electron beam over a wide range (field of view) of a sample, magnifies it with a magnifying lens system installed after the sample, and forms an image on a fluorescent plate. Analysis of minute parts is not possible.

Therefore, in order to analyze microscopic parts, the condenser lens above the sample is strongly operated to narrow down the electron beam.
A beam spot is applied to the sample and that part is analyzed. That is, the beam size of the electron beam applied to the sample is changed from large to small.

Naturally, at this time, only the shape of a small beam spot can be seen on the fluorescent plate, and no image of the sample can be observed.

Therefore, it is not clear which part of the sample is actually hit by the beam spot.

In conventional techniques, in order to align the beam spot with a desired position on the sample, for example, as shown in the literature (Water Volume; Applied Physics, Vol. 50, p. 1283 (1-981)) , This beam spot I is scanned two-dimensionally over the sample using the principle of a scanning electron microscope, and a scanned image of the sample is observed based on signals such as the sample-transmitted electron dose.
The beam spot was made to stop at a desired position on the sample.

Alternatively, set a mark at a specific position on the fluorescent plate 1 and set the device so that the spot will be at this position when the beam spot 1 is stopped. (hereinafter referred to as image m1ll observation mode), move the sample, and align the analysis target position with the above landmark.

Furthermore, after that, the transmission electron microscope was changed to the beam spot mode (hereinafter referred to as spot mode), the beam spot was set to 1, and analysis was performed, which was an extremely complicated operation.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an analytical television electron microscope that allows analysis points to be easily set while observing the sample image w1 when analyzing a minute part of a sample in a transmission electron microscope. be.

[Summary of the invention]

In order to achieve the above object, the analytical television electron microscope of the present invention takes a sample image of a fluorescent plate with a television camera, displays it on a long afterglow CRT, and furthermore, The present invention is characterized in that when switching to the analysis mode, the intensity of the input signal to the CRT is changed in synchronization with the mode switching.

[Embodiments of the invention]

'Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

In FIG. 1, an electron beam 2 emitted from an electron gun 1 installed in a mirror body 19 is connected to a condenser lens power source 17.
The light is focused by two condenser lenses 3 and irradiates the sample 4. An image of the electron source 1 is normally projected onto the sample 4 by this electron optical system.

Therefore, the size of the electron beam 2 that irradiates the sample 3 is adjusted by changing the lens currents of the two condenser lenses 3 and by changing the magnification of this lens system. That is, increasing the magnification rate increases the beam size, and decreasing the magnification rate decreases the beam size.

The sample 4 is observed with the beam size increased (image observation mode), and minute parts are analyzed with the beam size decreased (spot mode).

At this time, the current density of the electron beam 2 irradiating the sample 4 is
As shown in the figure, if the aperture angle of the electron beam 2 is kept at a constant value by the lens aperture 5, it will not change even if the beam size is changed. This is based on Langmuir's law of conservation of brightness regarding electron optical systems.

The electron beam 2 transmitted through the sample 4 is imaged by a magnifying lens 6 on a fluorescent plate 7-1- whose glass surface is coated with a fluorescent material.

This image is displayed on the CRTiO through a television camera 8 and a video signal amplifier 9.

The video signal amplifier 9 includes a changeover switch 11, low gain amplifiers 1 and 2, and a high gain amplifier 13. This changeover switch 11 is operated by a synchronization signal input through a signal line 14.

Naturally, in the image 11 mode, an image of a wide area of the sample 4 is visible on the CRTIO, and in the spot mode, a point-like image corresponding to the spot position of the electron beam 2 on the surface of the sample 4 is visible.

This spot image is created by the operator moving the beam position on the four surfaces of the sample using an electron beam deflector.
Move on Tl, 0. The operator determines the analysis point on the sample 4 while looking at this.

In this example, CRTiO with long afterglow properties is used, and when switching from image observation mode to analysis mode, CRTiO
At Tl,0, the afterimage of the sample image and the spot image appear to overlap, just as shown in the figure. Therefore, while looking at this afterimage, the operator can move the spot image superimposed on this image and stop the beam spot at an arbitrary position to determine the analysis point.

However, the spot image is extremely difficult to see compared to the sample image. This is because the electron beam density of the fluorescent plate 7J2, which is imaged by the television camera 8, is approximately the same in both the image observation mode and the spot mode, and in the spot mode, the spot only appears as a very small dot-like image. This is because the image cannot be seen. Therefore, in this embodiment, the television camera 8
A video signal amplifier 9 is provided between the CRT 10 and the CRT 10, the signal amplification factor of which is switched in accordance with the change in the operation mode.

That is, first, the electron microscope is set to image observation mode, and the television image is displayed on the CRTIO through the low amplification factor amplifier 12. Next, switch the electron microscope to spot mode, and at the same time,
The changeover switch 11 is connected to the high amplification factor amplifier 13 side.

As mentioned above, this operation is performed automatically through the overall controller 15 and the synchronization signal generator 16. A personal computer is used as the overall controller 15.

With this invention, a bright spot image can now be seen on the CRTIO, making it easier to determine the analysis point.

In addition, in this example, a long afterglow CRTIO was used in order to see the sample image and spot image superimposed;
I! The phosphor coated on the detection fluorescent plate 7 has a long afterglow property;
For example, the same effect can be obtained by using Zn25in4: or the like. Note that 18 is an X-ray analyzer.

〔Effect of the invention〕

As described above, according to the present invention, a bright spot image can be observed while viewing an image of a sample, and analysis points can be easily determined.

The present invention is useful not only for elemental analysis using X-rays or electron beam energy loss, but also for analyzing minute parts by narrowing the beam, such as in convergent electron beam diffraction.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an analytical television electron microscope according to the present invention. DESCRIPTION OF SYMBOLS 1... Electron gun, 2... Electron beam, 3... Condenser lens, 4... Sample, 5... Lens aperture, 6...
Magnifying lens, 7... fluorescent plate, 8... television camera,
9... Video signal amplifier, 10... CRT, 11.
... Selector switch, 12... Low amplification factor amplifier, 13.
...High amplification factor amplifier, 14...Signal line, 1-5...Overall controller, 16...Synchronization signal generator, 17...Condenser lens power supply, 18...X-ray analyzer, 19...・Electron microscope mirror body.

Claims (1)

[Claims] 1. A transmission electron microscope that can change the beam size of the electron beam that irradiates the sample, which is equipped with a television camera for observing images, a video signal amplifier, and a CRT, and the video signal amplifier An analytical television electron microscope characterized by being configured such that the amplification factor of the analysis can be changed.