JPH0313701B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron microscope whose field of view is moved electromagnetically.

[Prior Art] If the field of view is moved electromagnetically, that is, by deflection of an electron beam, the field of view can be moved at high speed, but the image quality is poor because the field of view is moved off the optical axis. On the other hand, if the field of view is moved by mechanically moving the specimen, the specimen can always be viewed directly below the optical axis, resulting in a high-quality image, but if the specimen is moved and stopped repeatedly, it takes time to move the field of view. . Therefore, the field of view is moved electromagnetically to capture the desired field of view in a short time, and based on the deflection signal value at that time, the captured part is moved directly below the optical axis and the deflection is turned off. It is proposed to observe a good quality image.

Incidentally, electron microscopes, which have a means for scanning an electron beam from an electron gun and enable observation of a transmission electron microscope image and a scanned image of a sample by switching an objective lens, are widely used today. In such electron microscopes, the viewing field is determined by moving the sample, so switching the observation mode between transmission electron microscope images and scanning images does not cause the field of view to change; When moving the observation mode, the field of view of the transmission electron microscope image and the field of view of the scanning image must be moved by separate deflection means, and in addition, when changing the excitation of the objective lens when changing the observation mode, Because the amount of rotation and deflection of the electron beam changes, the field of view shifts when the mode is switched. Therefore, when changing modes to observe the same field of view, the field of view must be moved electromagnetically every time the mode is switched, which is complicated.

[Object of the Invention] The present invention has been made to solve these conventional drawbacks, and provides an electron microscope that can maintain the initial field of view captured electromagnetically regardless of switching the observation mode. The purpose is to

[Structure of the Invention] The present invention provides an apparatus that has a means for scanning an electron beam from an electron gun and is capable of observing a specimen by switching between a transmission electron microscope image and a scanning image by switching the excitation of an objective lens. a first deflection means disposed below the sample for moving the field of view in the electron microscope image observation mode; a second deflection means disposed above the sample for moving the field of view in the scanning image observation mode; , means for generating a signal for specifying the amount of movement of the field of view by deflecting the electron beam, means for switching and supplying the signal from the signal generating means to the first and second deflecting means, and switching of an observation mode. The present invention is characterized by comprising means for converting the signal from the signal generating means so as to compensate for the movement of the visual field accompanying the movement of the field of view.

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

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, 1 is an electron gun, and an electron beam 2 from the electron gun 1 is focused by a focusing lens 3 and irradiated onto a sample 4. . 5 is an objective lens, 6 is a first,
This is an imaging lens system consisting of a second intermediate lens and a projection lens. Excitation current is supplied to these lenses or lens systems from lens power supplies 3L, 5L, and 6L, respectively. Reference numerals 7a and 7b denote two sets of scanning deflection coils for electromagnetically moving the field of view and scanning the sample in the scanning image observation mode. The scanning signal is supplied via the magnification switching circuit 9 and the adding circuit 10. The scanning signal from the scanning signal generation circuit 8 is sent to the deflection coil D of the cathode ray tube 11.
The cathode ray tube 11 is scanned in synchronization with the electron beam 2. 12 is a secondary electron detector;
The signal from the detector 12 is supplied to the grid G of the cathode ray tube 11 via an amplifier 13. 1
4a and 14b are two sets of deflection coils for electromagnetically moving the field of view in the transmission electron microscope image mode, and a deflection current can be supplied to these coils from a deflection power source 15. The scanning deflection coils 7a, 7b receive a signal from the deflection signal generator 19 of the control device 16 either directly via the first switching circuit 17 or after being converted by the second signal converter 20. It can be supplied via one switching circuit 17. Further, a signal from the deflection signal generator 19 can be supplied to the deflection power supply 15 via a first switching circuit 17 and a first signal converter 18. The control device 16 controls the lens system associated with switching the observation mode based on the signal from the input device 25, controls the magnification switching circuit 9 and the lens power source 6L based on the magnification designation signal, and controls the scanning deflection coils 7a, 7b. The observation mode switching control circuit 21, the magnification signal generator 22, the second switching circuit 23, the third signal The converter 24 also uses this control device 16.
included in. The input device 25 also has a joystick 25a for moving the field of view, an observation mode switching button 25b, a magnification adjustment knob 25c, a first conversion section adjustment knob 25d, and a second conversion section adjustment knob 25e. Further, when the field of view is moved based on the signal from the deflection signal generator 19, the first signal converter 18 converts the signal into a transmission image so that the same field of view as in the scanning image mode can be obtained even in the transmission electron microscope image mode. This is a circuit that converts for the mode, and this conversion function is the converter adjustment knob 25d of the input device 25.
Adjusted by. Moreover, the second signal converter 20
so that the same field of view on the sample is illuminated even when the observation mode is switched from scanning image mode to transmission image mode.
This circuit converts the signal of the deflection signal generator 19, and this conversion function is also adjusted by the conversion section adjustment knob 5e. Similarly, the third signal converter 24 is a circuit for converting the magnification signal from the magnification signal generator 22 so that observation can be performed at the same magnification regardless of switching of the observation mode. Further, 26 is a fluorescent screen for displaying a transmitted image.

In such a configuration, first, the input device 25
The first signal converter 18 is adjusted in advance using the converter adjustment knob 25d so that the direction and ratio of the movement of the field of view in the transmission image mode and the scanning image mode match, and the objective lens 5 is also switched. Regardless, the second signal converter 20 is adjusted by the converter adjustment knob 25e so that the electron beam 2 is irradiated to the same position. Therefore, for example, when attempting to observe a sample using a scanned image for the first time, the observation mode switching button 25b of the input device 25 is operated to supply a signal instructing the observation mode switching control circuit 21 to observe the scanned image. As a result, a control signal is supplied from the observation mode switching control circuit 21 to the scanning signal generation circuit 8, the focusing lens power source 3L, and the objective lens power source 5L, the focusing lens 3 and the objective lens 5 are strongly excited, and the scanning signal is generated. A scanning signal is generated from the circuit 8 and supplied to the scanning deflection coils 7a and 7b. Therefore, as shown in FIG. 2, the electron beam 2 is narrowly focused and irradiated onto the sample 4 by the focusing lens 3 and the front magnetic field lens 5a of the objective lens 5, and is scanned over the sample 4. At the same time, the observation mode switching control circuit 21 sends a switching signal to the first switching circuit 17 to switch this circuit to the connection state shown by the dotted line.
The output signal of the deflection signal generator 19 is supplied to the scanning deflection coils 7a and 7b via the adder circuit 10, and a switching signal is sent to the second switching circuit 23 so that the signal of the magnification signal generator 22 changes to the magnification. so that it is supplied to the switching circuit 9. Therefore, if a desired magnification is set using the magnification adjustment knob 25c, a magnification signal corresponding to this magnification is supplied to the magnification switching circuit 9, so that a scanned image of the desired magnification is generated based on the image signal from the detector 12. displayed on the cathode ray tube 11.
Therefore, if the deflection signal generated by the deflection signal generator 19 is changed by operating the joy stick 25a while observing this image, the center of scanning by the electron beam 2 will move, so that the scanning displayed on the cathode ray tube 11 will change. The field of view of the image moves.

Now, when a certain field of view is being observed in this way, if you want to observe the same field of view with a transmission electron microscope image, you can use the observation mode switching button 25b of the input device 25 to change the observation mode switching control circuit 2.
1 is supplied with a signal instructing observation of a transmitted image. As a result, a control signal is supplied from the circuit 21 to the scanning signal generating circuit 8, the focusing lens power source 3L, and the objective lens power source 5L, and the generation of the scanning signal from the scanning signal generating circuit 8 is stopped, and the focusing lens 3 and the objective lens 5 are stopped. Make the excitation weaker. Therefore, the electron beam 2 is irradiated onto the sample 4 as a well-paralleled electron beam by the focusing lens 3, and the image of the electron beam transmitted through the sample is captured by the rear magnetic field lens 5b of the objective lens 5 shown in FIG. An image is formed on the object surface of the imaging lens system 6, and a transmitted image of the sample is displayed on the fluorescent screen 26. At the same time, observation mode switching control circuit 2
1 switches the first switching circuit 17 to the connection shown by the solid line in FIG. Therefore, the deflection signal generator 1
The signal from 9 is supplied to the scanning deflection coils 7a and 7b via the second signal converter 20, and is also supplied to the deflection power source 15 via the first signal converter 18. The signal supplied to the deflection power supply 15 is the first
Since the signal conversion unit 18 converts the image so that the same field of view as in the scanning image viewing mode can be obtained, a transmitted image with the same field of view as in the scanning image viewing mode can be obtained on the fluorescent screen 26. . or,
The deflection signal from the deflection signal generator 19 is converted by the second conversion unit 20 so as to compensate for the shift in the electron beam irradiation position due to switching of the excitation of the objective lens 5, and then converted to the scanning deflection coil 7a. , 7b, the electron beam 2 illuminates the center of the field of view observed in a transmission electron microscope image. Therefore, a bright transmission electron microscope image can always be observed. Furthermore, at the same time, by switching the second switching circuit 23 by the observation mode switching control circuit 21, the magnification signal converted by the third converting section 42 is supplied to the power source 6L. Images at the same magnification can be observed. On the other hand, when switching the mode from a transmission image to a scanning image, the first switching circuit 17 and the second switching circuit 23 are switched in the opposite manner to the above-described case, so that images of the same field of view can be observed.

In the above-mentioned embodiment, the signal from the deflection signal generator is converted by the signal converter and supplied to the deflection means, thereby eliminating the movement of the field of view due to mode switching. The deflection current value data necessary to move the field of view by (x, y) in the X direction and the Y direction for both the image and the scanning image is examined for each (x, y) value, and these data are The transmitted image and the scanned image are stored in separate tables, and the observation mode switching control circuit 2
The table to be read is switched by the signal from the deflection signal generator 19, and the address to be read is designated by the signal from the deflection signal generator 19, the corresponding data is read out and substantially converted, and the deflection current is supplied based on this data. You can also do it.

[Effect] As is clear from the above explanation, according to the present invention, in an apparatus that switches the observation mode between a transmission electron microscope image and a scanning image by switching the objective lens, etc., even if the observation mode is switched, the electromagnetic You can move the field of view and maintain the initial field of view for observation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing an excitation state of an objective lens in a scanning image observation mode. 1: Electron gun, 2: Electron beam, 3: Focusing lens,
4: sample, 5: objective lens, 6: imaging lens system,
7a, 7b: scanning deflection coil, 8: scanning signal generation circuit, 9: magnification switching circuit, 10: addition circuit, 1
1: Cathode ray tube, 12: Secondary electron detector, 13: Amplifier, 14a, 14b: Deflection coil, 15: Deflection power supply, 16: Control device, 17, 23: Signal switching circuit, 18, 20, 24: Signal conversion Part, 19: Deflection signal generator, 21: Observation mode switching control circuit, 2
2: Magnification signal generator, 25: Input device, 25a:
Joy stick for moving field of view, 25b: Observation mode switching button, 25c: Magnification adjustment knob, 25d,
25e: Conversion part adjustment knob, 26: Fluorescent screen.

Claims (1)

[Claims] 1. It has a means for scanning the electron beam from the electron gun,
In a device that allows viewing of a specimen by switching between a transmission electron microscope image and a scanned image by switching the excitation of an objective lens, a first a second deflection means disposed above the sample for moving the field of view in the scanning image observation mode; and means for generating a signal for specifying the amount of movement of the field of view by electron beam deflection; means for switching and supplying the signal from the signal generating means to the first and second deflecting means, and converting the signal from the signal generating means to compensate for movement of the field of view accompanying switching of observation modes; An electron microscope characterized by comprising means for.