JPH0935676A - electronic microscope - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide an electron microscope suitable for accurately and easily irradiating a position on a sample corresponding to a selected position on an image region of interest with an electron beam. To provide. [Structure] An electron microscope image of a sample 21 is formed on a scintillator 2 and taken by a TV camera 5 to monitor 1.
4-1 is displayed. On the other hand, the cathode ray of the TV camera is deflected and its deflection width is changed to select an arbitrary region in the image on the monitor 14-1. An enlarged image of this selected area is displayed on the monitor 14-2. The irradiation electron beam of the sample 21 is moved to the sample upper region corresponding to the selected region, and the X-rays emitted from the sample in this state are X-rays.
It is detected and analyzed by the line element analyzer 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron microscope, and more particularly, to a transmission electron microscope of a type which picks up and displays a magnified image of a sample formed by an imaging lens system.

[0002]

2. Description of the Related Art In a transmission electron microscope, it is general practice to take a magnified image of a sample formed by an imaging lens system with a TV camera and display it on a CRT monitor. It is also common practice to detect X-rays generated from a sample and perform elemental analysis of the generation region. To perform this analysis, first observe the image displayed on the monitor and select the region of interest, then move the sample or electron beam to correspond to the position of the region of interest on the image. The position on the sample to be irradiated is irradiated with an electron beam, and the X-ray generated from the sample at that time is detected.

[0003]

However, even if it is easy to select the region of interest in the image, the position on the sample corresponding to the position of the region of interest can be accurately irradiated with the electron beam. It is usually not easy to conduct elemental analysis.

Therefore, an object of the present invention is to provide an electronic beam at a position on the sample corresponding to the position of the selected on-image region of interest.
An object of the present invention is to provide an electron microscope suitable for enabling accurate and easy irradiation with a beam.

[0005]

According to the present invention, an irradiation lens system for irradiating the sample with the electron beam so as to focus the electron beam on the sample, and the irradiation lens system for transmitting the sample by the irradiation. An imaging lens system for forming a magnified image of the sample by an electron beam, a means for picking up the formed sample magnified image, a means for displaying the picked-up sample magnified image, and the displayed sample An electron microscope is provided which is provided with means for selecting a region of a magnified image and means for changing an irradiation position of the sample by the electron beam in association with the region selecting means.

According to another aspect of the present invention, the electronic beam
Means are provided for varying the area of illumination of the sample by the system in relation to the area selecting means.

According to still another aspect of the present invention, means for changing the irradiation position of the sample by the electron beam and the size of the electron beam at the irradiation position in association with the area selecting means. Is provided.

According to another aspect of the present invention, the imaging means includes a TV camera device, the TV camera device converting the magnified image of the sample into an optical image, and converting the optical image into a charge image. And a means for scanning the charge image with a cathode ray beam, wherein the area selection deflects the cathode ray beam and the size and position of the scan area of the charge image by the cathode ray beam. Is done by changing.

According to still another aspect of the present invention, it comprises means for amplifying an electric signal and means for changing the amplification degree of the amplifying means, and the image pickup means picks up the enlarged sample image to obtain the electric signal. The display means is configured to display the magnified image of the sample based on the amplified electric signal, and at least one of the irradiation lens system and the imaging lens system has a lens thereof. The condition can be changed, and the means for changing the amplification degree is configured to change the amplification degree of the signal amplification means in association with the change of the lens condition.

[0010]

FIG. 4 conceptually shows a part of a TV camera system for an electron microscope according to the present invention. The electron beam 1 projected by the final stage projection lens of the image forming lens system of the electron microscope forms an enlarged image of the sample on the scintillator 2. The scintillator 2 converts the intensity of the magnified image into the intensity of light. That is, the magnified image of the sample formed by the imaging lens system is converted into an optical image by the scintillator 2.

The converted optical image is formed on the target 4 of the TV camera 5 via the optical lens 3. Membrane target
In the get 4, electron-hole pairs are formed according to the light intensity. That is, the optical image is converted into a charge image by the target 4. A voltage of about 800 V is applied to the target 4 by the high voltage source 8. TV camera 5
An electron beam 6 which is a cathode ray beam is emitted from the electron source 15 and is focused finely on the target 4. Further, the electronic beam 6 is moved to a normal T by the scanning coil 7 of the TV camera 5.
It is deflected two-dimensionally at the V frequency, so that the target 4 is two-dimensionally scanned by the electron beam 6 at the same frequency.

When one point on the target is irradiated with the electron beam 6 during the scanning process, the electrons accumulated at that point
The electric current corresponding to the hole pair is obtained. This current signal is displayed on the CRT monitor 14 via the amplifier 9. In this way, an enlarged image of the sample, that is, an electron microscope image is displayed on the monitor 14.

Power sources 10 and 12 are connected to the scan coil 7 and the monitor scan coil 11 of the TV camera 5, and these power sources are controlled by a signal generator 13. The amplitudes of the scanning signals from the power supplies 10 and 12 can be controlled independently.

FIG. 2 shows an example of an image displayed on the monitor 14 of FIG. The effective area of the target 4 of the TV camera is usually 1 inch. An image obtained by scanning the entire area with the electronic beam 6 is shown as an area 1 ((1) in FIG. 2). Images obtained by scanning a part of the target 4 with the electronic beam 6 are shown in regions 2, 3 and 4 ((1) of FIG. 2). Monitor scanning coil 7 even when a part of target 4 is scanned
If the amplitude of the signal is not changed, an enlarged image of each area is displayed on the entire surface of the monitor 14 as shown in (2) to (4) of FIG.

FIG. 3 shows the signal level of the TV camera scanning coil 7 in the X-axis direction. 3A shows the signal level v1 corresponding to the area 1 in FIG. 2, and FIG. 3B shows the signal level v2 corresponding to the areas 2, 3 and 4.
The positions of regions 2, 3 and 4 can be controlled by the DC voltage vd. That is, the scanning area can be moved to an arbitrary position in the X-axis direction of the area 1 by changing the DC voltage vd. Further, the position and the amplitude can be similarly controlled in the Y-axis direction.

FIG. 1 conceptually shows the overall structure of an electron microscope according to the present invention. Electron source 1 of electron microscope
From 6, an electron beam is generated. The irradiation lens system 18 works to irradiate the sample 21 with the electron beam in order to converge the generated electron beam on the sample 21. The electron beam can be finely moved in the two-dimensional direction on the surface of the sample 21 by the electron beam deflection coil 19 of the electron microscope. Further, the sample 21 can be two-dimensionally moved in the X and Y axis directions by the sample fine movement device 20.

The electron beam transmitted through the sample is converted into an enlarged image of the sample by the image forming lens system 22 of the electron microscope.
Form on top. The output signal from the TV camera passes through the signal amplifier 9 and further through the switch 27, and the CRT monitor 14
The magnified image of the sample is displayed on -1 or 14-2. The irradiation lens system 18, the electron beam deflection coil 19, the imaging lens system 22, and the sample fine movement device 20 are respectively control devices 23 and 24,
It is controlled by the arithmetic and control unit 27 via 25 and 26. The arithmetic and control unit 28 also controls the TV camera scanning coil power supply 10, the signal amplifier 9, the monitor scanning power supplies 12-1 and 12-2 for the monitor scanning coils 11-1 and 11-2, and the switch 27. The arithmetic and control unit 28 further includes a magnification setting device 30 and a beam irradiation position setting switch 3.
5 and a cursor setting device 37 are connected, and a character generator 34 and a switch 38 are connected between the arithmetic and control unit 28 and the switch 27. In addition, 3
Reference numeral 3 denotes an image memory.

In the above configuration, the operation and operation of the system are performed as follows.

1) Set the magnification of the electron microscope to a predetermined value. This is done by operating the magnification setter 30 and thereby changing the lens conditions of the imaging lens system 22.

2) Scan area 1 in FIG.
The electron microscope image corresponding to is captured by the TV camera 5 and displayed on the monitor 14-1 via the switch 27. This is possible by giving the signal of (1) of FIG. 3 to the TV camera operating coil 7. The image is displayed and stored in the image memory 33 until the next instruction is given.

3) When the switch 27 is turned on, a cursor (for example, a rectangular cursor) is generated by the character generator 34 and displayed on the monitor 14-1 so as to be superimposed on the image.

4) The position and size of the area desired to be enlarged in the area 1 is monitored 14-1 by using the cursor setting device 37.
Select above. That is, if the area 2 in (1) of FIG. 2 is selected, the cursor is moved to the area 2 and overlapped. The amount of movement of the cursor is converted into the DC voltage vd shown in (2) of FIG. 3, and the size of the selected area (rectangular curve) is calculated.
Sol size) is converted to v2.

5) When the beam irradiation position setting switch 35 is turned on, the switch 27 is switched to the monitor 14-2 side, and the arithmetic and control unit 28 further controls the scanning coil power supply 10 of the TV camera to make the car. Of region 2 selected by sol,
A signal whose position is vd and whose size is v2 is applied to the scanning coil 7 of the TV camera. As a result, the scanning coil power supply 10 of the TV camera provides the scanning coil 7 with the signal (2) in FIG. 3 having a magnitude v2 and a direct current level vd. Therefore, the output signal from the TV camera 5 is as shown in FIG. The enlarged image signal of the area 2 of (1) is displayed on the monitor 14-2 via the switch 27. Thus, a low-magnification image of the sample is displayed on the monitor 14-1 and a high-magnification image of the sample is displayed on the monitor 14-2 at the same time.

6) When the beam irradiation position setting switch 35 is turned on, the arithmetic and control unit 28 is further operated by the control unit 2.
4 to change the electron beam to a position on the sample 21 corresponding to the position of the selected area (corresponding to vd) Coil 1
Deflection by 9 and controlling the control device 23,
The lens condition (convergence condition) of the irradiation lens system 18 is changed so that the size of the electron beam on the sample 21 corresponds to the size of the selected region (corresponding to v2). In this state, the X-rays emitted by the electron beam irradiation from the sample are detected by the X-ray elemental analyzer 17 and elemental analysis is performed. Therefore, when the X-ray analysis is performed, it is possible to accurately and easily confirm the analysis region, and when the X-ray analysis is performed, it is possible to always observe the region where the analysis is performed.

The sample may be moved instead of deflecting (moving) the electron beam for irradiating the sample. In this case, it is necessary to deflect (move) the cathode ray beam of the TV camera together with it.

As can be seen from the above description, the position on the sample corresponding to the position of the selected sample image area is automatically determined, and the electron beam is automatically matched to that position. Therefore, it is understood that the irradiation by the electron beam at that position is accurately and easily performed. This results in that X-ray analysis can be done accurately and efficiently. Further, not only the position of the selected sample image area but also the size on the sample corresponding to the size of the area is automatically determined, and the electron beam is automatically narrowed down to the determined size. Therefore, the X-ray analysis can be performed more efficiently.

Further, since it is not necessary to change the magnification of the imaging lens system in order to obtain a magnified sample image of the selected sample image area, the axis deviation of the electron beam and the astigmatism caused by the change of the magnification are caused. The problem of occurrence does not occur.

When the size of the electron beam on the sample changes, the amount of the electron beam per unit area changes, so that the brightness of the image changes. Therefore, the arithmetic and control unit 28 changes the amplification degree of the amplifier 9 so that the brightness of the image does not change even if the lens condition of the irradiation lens system 18 is changed, and the image brightness is kept substantially constant. Also, when the lens condition of the imaging lens system 22 is changed to change the magnification of the lens system, that is, when the magnification of the sample image on the scintillator 2 is changed, the electron beam amount per unit area changes. As a result, the brightness of the image changes. Therefore, also in this case, the arithmetic and control unit 28
Changes the amplification degree of the amplifier 9 so that the brightness of the image does not change even if the lens condition of the imaging lens system 22 is changed, and is kept substantially constant.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the overall configuration of an electron microscope according to an embodiment of the present invention.

2 is a diagram showing an example of an image displayed on a monitor 14 of FIG.

FIG. 3 is a diagram showing signal levels in the X-axis direction of the TV camera scanning coil of FIG.

FIG. 4 is a conceptual diagram of a part of a TV camera system of an electron microscope according to the present invention.

[Explanation of symbols]

2: Scintillator, 3: Optical lens, 4: Target,
5: TV camera, 6: Electronic beam of TV camera :, 7:
Scanning coil of TV camera, 8: high voltage source, 9: amplifier,
10: Scan coil power supply for TV camera, 11: Monitor scan coil power supply, 12: Monitor scan coil power supply, 13: Signal generator, 14: CRT monitor, 17: X-ray elemental analysis device, 1
8: irradiation lens system, 19: electron beam deflection coil, 2
0: sample fine movement device, 21: sample, 22: imaging lens system,
23: irradiation lens system control system, 24: electron beam deflection coil control system, 25: sample fine movement device control system, 26, imaging lens system control system, 27: switch, 28: arithmetic control device 30: magnification setting device, 33 : Image memory, 34: character generator, 35: beam irradiation position setting switch, 37: cursor setting device.

Claims (6)

[Claims] 1. An irradiation lens system for irradiating the sample with the electron beam so as to converge the electron beam on the sample, and an enlarged image of the sample by the electron beam transmitted through the sample by the irradiation. An image forming lens system for forming, a means for picking up the formed sample magnified image, a means for displaying the picked up sample magnified image, and a means for selecting a region of the displayed sample magnified image, A means for changing the irradiation position of the sample by the electron beam in association with the area selecting means. 2. An irradiation lens system for irradiating the sample with the electron beam so as to converge the electron beam on the sample, and an enlarged image of the sample by the electron beam transmitted through the sample by the irradiation. An image forming lens system for forming, a means for picking up the formed sample magnified image, a means for displaying the picked up sample magnified image, and a means for selecting a region of the displayed sample magnified image, And a means for changing an irradiation area of the sample by the electron beam in association with the area selecting means. 3. An irradiation lens system for irradiating the sample with the electron beam so as to focus the electron beam on the sample, and an enlarged image of the sample by the electron beam transmitted through the sample by the irradiation. An image forming lens system for forming, a means for picking up the formed sample magnified image, a means for displaying the picked up sample magnified image, and a means for selecting a region of the displayed sample magnified image, An electron microscope comprising: an irradiation position of the sample by the electron beam and a means for changing the size of the electron beam at the irradiation position in association with the area selecting means. 4. The electron microscope according to any one of claims 1 to 3, wherein the imaging means includes a TV camera device, the TV camera device converting the magnified image of the sample into an optical image, and the device. The means for converting the optical image into a charge image and the means for scanning the charge image with a cathode ray beam, the area selection deflects the cathode ray beam and the cathode ray beam.
The electron microscope is characterized in that the scanning is performed by changing the size and position of the scanning area of the electric charge image by the scanning electron microscope. 5. The electron microscope according to any one of claims 1 to 4, comprising means for amplifying an electric signal and means for changing the amplification degree of the amplification means, and the image pickup means for displaying the magnified image of the sample. The display means is configured to display the magnified image of the sample based on the amplified electric signal, and the display means is configured to display the magnified image of the sample based on the amplified electric signal. At least one of them is configured to be able to change the lens condition thereof, and the means for changing the amplification degree is configured to change the amplification degree of the signal amplification means in association with the change of the lens condition. An electron microscope. 6. The electron microscope according to claim 1, wherein the display means displays a monitor for displaying the magnified image of the sample, and the magnified sample in a selected region of the magnified image of the displayed sample. An electron microscope including a monitor for displaying an image.