JPS59148254A - Sample shifting device of scanning electron microscope or the like - Google Patents

Abstract

PURPOSE:To obtain a desired visual field simply and in a short time by a method in which a mark serving as a sign for the visual field shifting is indicated in a display means, while a sample is automatically shifted so that a position on the sample corresponding to the mark may be displayed in the center of screen, basing on a signal indicating a magnification and a signal indicating the position of the mark. CONSTITUTION:An electron beam 2 emitted from an electron gun 1 is focussed by a focusing lens 3 for irradiating a sample 4. The output signal of the secondary electron detector 10 for detecting the secondary electrons generated from the sample 4 is fed to the cathode-ray tube 9 as the brightness signal through an amplifier 11 and a spot adding circuit 12. The sample stage 13 can be shifted in the horizontal-and-vertical directions by pulse motors 14X and 14Y. An input device 23 is connected to a control device 16 for controlling the spot display and the motor driving while push button switches 23a-23d are provided for shifting the spot both vertically and laterally in the screen of the cathode-ray tube 9. Also said input device 23 is provided with a knob 23e for indicating the magnification to be observed and a setting switch 23f giving instruction for making the position on the sample corresponding to the spot to be shifted on the optical axis 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sample moving device such as a scanning electron microscope, which moves a field of view by moving a sample.

[Prior Art] Recently, scanning electron microscopes have been used to observe large samples such as integrated circuit elements at low magnification. In such a case, if the field of view is moved by electromagnetic deflection, the electron beam will scan at a position quite far from the optical axis.
Aberrations become large, making it impossible to obtain a high-quality image. Therefore, in this advantageous apparatus, the field of view is changed by moving the sample. Conventionally, this movement of test r1 was carried out by button operation, for example, while the button was pressed, the sample continued to move, and when the button was released, test r1 stopped, but unless the operator was an experienced operator, the timing of releasing the button was difficult. It is difficult to obtain a desired field of view with a single button operation. Therefore, the desired field of view can be obtained after pressing the button several times, but since it takes time to mechanically move the sample, it is not possible to easily and quickly obtain the desired field of view. could not.

Also, when the area of interest of the sample is displayed at the edge of both sides, the magnification may be lowered to display the area close to the center of the screen and then the field of view is selected. In such cases, in the past, the magnification was manually changed each time, which was cumbersome, and the user could momentarily lose sight of the area of interest as the magnification was changed, making it impossible to smoothly select the field of view. .

[Object of the Invention] The purpose of the present invention is to solve these conventional drawbacks and to provide a portable equipment for a scanning electron microscope, etc., which can easily obtain a desired field of view in a short time. It is something to do.

[Structure of the Invention] The present invention provides a means for two-dimensionally scanning an electron beam in L-L, and a means for scanning in synchronization with the scanning of the electron beam and supplying a detection signal accompanying the scanning of the electron beam. In the apparatus, the apparatus includes a display means for displaying a sample image based on the display, a magnification switching means for switching the magnification by switching the scanning width of the electron beam, and a sample moving means for moving the sample r1. Means for displaying a mark as a landmark for moving the field of view on the child 〇, and a position on the sample corresponding to the mark is displayed in the center of both sides based on a signal representing the magnification and a signal representing the position of the mark. 3- Means for automatically moving the sample as shown in FIG.

The present invention further provides a means for two-dimensionally scanning an electron beam on a sample, and a means for scanning in synchronization with the scanning of the electron beam, and displaying a trial r1 image based on the supply of a detection signal accompanying the scanning of the electron beam. In the apparatus, the display means includes a display means for moving the field of view, a magnification switching means for switching the magnification by switching the scanning width of the electron beam, and a sample moving means for moving the sample. means for displaying a mark as a landmark; means for automatically lowering the magnification by controlling the magnification switching means when the position of the mark moves to the edge of the screen; a signal representing the magnification; and the mark. The present invention is characterized by comprising means for automatically moving the sample so that the position on the sample corresponding to the mark is displayed in the center of the screen based on a signal representing the position of the mark.

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

FIG. 1 is a diagram showing an outline of an embodiment of the present invention, in which numeral 1 is an electron gun, and an electron beam 2 of the electron gun 1J is focused by a focusing lens 3 onto a sample 4. irradiated. 5X and 5Y are deflection coils, and a sawtooth scanning signal is supplied from a scanning signal generation circuit 6 to these deflection coils 5X and 5Y via a magnification switching circuit 7. 8X and 8Y are amplifiers. The scanning signal from the scanning signal generating circuit 6 is also supplied to the deflection coil S of the cathode ray tube 9, and the cathode ray tube 9 is scanned in synchronization with the electron beam 2. 10 is a secondary electron detector for detecting secondary electrons generated from the sample 4, and the output signal of this detector 10 is amplified in an amplifier 11 and then sent to the cathode ray tube via a bright spot adding circuit 12. 9
is supplied as a luminance signal to 13 is a sample stage on which the sample 4 is placed, and this sample stage is driven by a pulse motor 14. X and 14Y allow movement in the X (horizontal) direction and Y (vertical) direction. 15 is a drive circuit that generates drive pulses for rotating the pulse motors 14X and 14Y. Reference numeral 16 denotes a control device for controlling the display of the bright spot and the drive of the motor, and this control device 16 includes a bright spot signal generation circuit 17. Motor drive control circuit 1
8. One up/down counter.

Register 20. It consists of a comparator 21.1/C circuit 22. The bright spot signal generating circuit 17 is supplied with a signal synchronized with the scanning signal from the scanning signal generating circuit 6, generates a bright spot display pulse at a predetermined timing using the synchronization signal as a starting point, and uses this pulse to display the bright spot. It is supplied to the adder circuit 12. The control signal from the drive control circuit 18 is supplied to the drive circuit 15, and the drive control circuit 18' controls the number of drive pulses generated by the drive circuit 15 to control the motor 1/1.
Controls the amount of rotation of IX and 14Y. An input device 23 is connected to the control device 16 in order to cause the control device 16 to perform controls such as those related to -. This input device 23 includes push button switches 23a, 23b, 2 for moving the bright spot up, down, left and right on the screen of the cathode ray tube 9.
3c and 23d are provided. Further, this input device is equipped with a heir 23e for instructing the observation magnification and a set switch 23f for giving a command to move the point on the sample corresponding to the bright spot onto the optical axis 24.

In this J:Una configuration, first, the legitimate child 2 of the input device 23
Set the observation magnification to M by operating 3e.

As a result, a digital value representing the observation magnification value M is stored in the register 20. Since the signal corresponding to the value M from this register 20 is supplied to the magnification switching circuit 7, the peak value of the scanning signal from the scanning signal generating circuit 6 is switched to the value corresponding to the observation magnification M in this circuit 7. A bundle in which a scanning signal with such a peak value is supplied to a deflection coil,
The electron beam 2 scans the sample 4 two-dimensionally. At this time, the cathode ray tube 9 receives an X (horizontal) direction scanning signal synchronized with this scanning from the scanning signal generating circuit 6 with a period T as shown in FIG. is the number of horizontal scanning lines constituting one screen), a sample image with a magnification of M is displayed based on the signal from the secondary electron detector 10. When the push button switches 23a, 23h, etc. for moving the bright spot are not pressed, the count value of the up/down counter 197- is 0, so the bright spot signal generation circuit 17 receives a signal from the up/down counter 19. 2 (IT) at a timing delayed by T/2 with respect to the second horizontal synchronization signal after the vertical synchronization signal is supplied. Generates a bright spot display pulse. This pulse is applied to the bright spot addition circuit 1
2 is added to the image signal, a bright spot Pa is displayed at the center of the screen of the cathode ray tube 9, as shown in FIG. 3(a'). Then, the operator, for example, presses the push button switch 23d.
When pressed for unit time τ, up/down counter 19 counts up by 10, and this counter 19
Since this numerical signal is supplied to the bright spot signal generating circuit 17, the bright spot signal generating circuit 17 generates T/2+1 based on the /second horizontal synchronizing signal as shown in FIG. 2(C).
0T/240 (however, half the horizontal length of the screen is 12
A bright spot display pulse is generated with a timing delayed by 0), and the bright spot moves 1 to the right of the screen.
It moves by a step (ie, 1/24) to become 8-Pl in FIG. 3(a). Next, for example, press the push button switch 23C for a time of 3τ (if you press the button and reverse it,
Since the up/down counter 19 counts down by 30, a signal corresponding to -20 is supplied from the counter 19 to the bright spot signal generation circuit 17. As a result, the bright spot signal generating circuit 17 generates a signal of /2 as shown in FIG.
T/2-20T/24 starting from the th horizontal synchronization signal
Since the bright spot display pulse is generated at a timing delayed by 0, the bright spot moves three steps to the left as shown in Fig. 3 (a >
When the push button switch 23a or 23b is pressed in the same way, the count value of the other up/down counter changes (not shown).
Based on this count value signal, the horizontal synchronization signal that is the starting point of the bright spot display pulse generated by the bright spot signal generation circuit 17 changes, and the display position of the bright spot can be moved in the vertical direction. Therefore, the push button switches 23a, 2 are
By operating 3b, 23c, and 23d, the bright spot is moved to the center of the screen by the movement of test 111, to a portion of the visual field that is desired to be moved, for example, P3. Therefore, when the set switch 23f is pressed, a signal instructing the drive control circuit 18 to supply a drive control signal is supplied from the switch 23f. At this time, the drive control circuit 18 receives a signal @Ux from an up-down counter 19, a signal Uy from another up-down counter (not shown) representing the vertical position of the score, and an observation magnification M from a register 20. Since the signals are supplied, the motors 14X, 1
A control signal is supplied to the drive circuit 15 to generate drive pulses for rotating 4Y by angles AUx /M and AUy /M (where A is a proportionality constant), respectively. As a result, the sample 4 is moved by the actual distance in the X direction and the distance in the Y direction from the center of the screen (order Pa) to the bright spot P3 and placed on the optical axis 24, and the image indicated by the bright spot P3 is The section will automatically be displayed in the center of the screen. On the other hand, the drive control circuit 18
When the next control signal is supplied, the signal from the switch 23f is supplied to the up/down counter 19 etc. after a slight delay time, and the up/down counter is cleared. Therefore, the signal supplied from the up/down counter 19 to the bright spot signal valve circuit 17 becomes O, and the position of the bright spot displayed on the screen also changes due to the above-mentioned visual field shift.
Move to the center position of Po along with J.

Furthermore, while observing this image, you can find areas of the image that are of interest to you.
1l! Suppose that H is at the edge of the screen. In such a case, when the operator moves the bright spot to the right side of the screen by operating the push button switch 23d, the count value of the up/down counter 19 increases, but the bright spot does not change as shown in FIG. (a)
Suppose that the count value reaches 100 by moving to the position P4 indicated by the dotted line Q (not displayed on the screen), then the output value of the up-down counter 19 and the reference value 100 corresponding to the position of the dotted line Q Comparator 21 that compares
supplies a response signal to the 1/C circuit 22 and causes the circuit 22 to perform an operation. The 1/C circuit 22 has a register 2.
Since a signal corresponding to a magnification value M from 0 is supplied, this calculation increases the magnification value M by 1/C (C is 2, for example).
A signal corresponding to the multiplied value M11-/C is generated, and this multiplication value signal is newly stored in the register 20. Due to this change in signal value, the magnification switching circuit 7 increases the amplification factor of the scanning signal so that the observation magnification becomes M/C. As a result, the area H of interest is displayed more centrally on the screen of the cathode ray tube 9, as shown in FIG. 3(b). On the other hand, since the output signal of the up/down counter 19 is also supplied to the 1/C circuit 22 (actually, the other 1/C circuit provided separately), the calculation by the 1/C circuit 22 is As a result, the circuit 22 increases the count value of the up/down counter 19 to 100 by 1/C.
The multiplied value 100/C is output, and this value is newly set in the up/down counter 19. Therefore, the bright spot P4 moves to the point P5 in FIG. 3(b), and is displayed at the same point relative to the area H on the lower magnification screen.

Then, if the switch 23d is further pressed for a time of 2τ,
Up/down counter 190 counts up to 100/C
+20, and at this time, the output pulse from the bright spot signal generation circuit 17 becomes 12- as shown in FIG. 2(e), so the bright spot Ps moves two steps to the right and becomes the bright spot in FIG. It becomes point P6. If the position of this bright spot P6 is the part of the image that you want to move to the center of the screen,
Now press the set switch 23f. As a result, as in the case described above, the drive control circuit 18 controls the bright point P based on the signal corresponding to 100/C+20 from the up/down counter 19 and the signal corresponding to M/C from the register 20.
A drive control signal is sent to the drive circuit 15 to move the sample stage 13 by the actual distance in the X direction between 6 and the point (Po) at the center of the screen. As a result, the drive circuit 15 drives the motor 14
A driving pulse is supplied to X to move the motor 14X at an angle A (1
Rotate by 00/C+20)/(M/C) and bright spot P
A point on the sample at position 6 is placed on the optical axis 24.

While the sample 4 is being moved in this manner, a signal from the set switch 23f is supplied to the register 20, and the value stored in the register 20 is returned to a signal representing the magnification M given by the legitimate child 23e. Therefore, the magnification switching circuit 7 is switched to set the observation magnification to M. Furthermore, drive control circuit 1
After 8 is activated, a signal from the set switch 2]J: is supplied to the up/down counter 19, clearing the counter 19, and setting the output of the counter 19 to O. Therefore,
As the bright spot Pε moves to the center of the screen, the part corresponding to the bright spot P6 moves to the center of the screen, and an image as shown in FIG. 3(C) is obtained.

In addition, in the above explanation, for the sake of simplicity, we have explained the case where the bright spot moves only in the A desired image is displayed by control.

Note that the present invention is not limited to the embodiments described above, and can be modified in many ways. For example, in the above-described embodiment, a bright spot is displayed as a landmark, but it is also possible to display a bright line movable in the horizontal and vertical directions, and use the intersection of these two bright lines as a mark. It's okay. Alternatively, a surrounding line of a certain size may be displayed as a mark, or an area of a certain size may be displayed with higher brightness or higher contrast than other parts to distinguish it from others. It's okay.

[Effects] As described above, in the apparatus based on the present invention, the bright spot, which can be moved in a short time with good responsiveness, is moved to a desired image area using an instruction means such as a push button switch, and then the sample is automatically moved. Since the field of view can be moved so that this part is brought to the center of the screen, the field of view selection IR can be performed easily and in a short time even in an apparatus in which the field of view is selected by moving the sample.

Furthermore, in the present invention, when the bright spot moves to the edge of the image in pursuit of an image area of interest, the observation magnification is automatically reduced by a certain ratio, allowing the area of interest to be displayed in the center of the screen. This is convenient because it eliminates the need to change the magnification, and the position of the bright spot also moves while keeping its relative position to the image unchanged as the magnification changes, making it easy to lose track of the position of the initial score. It is possible to quickly move the bright spot and select a field of view without any trouble.

[Brief explanation of drawings]

15- Figure 1 is a diagram showing one embodiment of the present invention, Figure 2 is a diagram showing output signals from each circuit shown in Figure 1, and Figure 3 is a diagram showing the display on a cathode ray tube screen. FIG. 3 is a diagram for explaining changes. 1: Electron gun, 2: N particle beam, 3: Converging lens, 4: Sample,
5X, 5Y: Deflection coil, 6: Scanning signal generation circuit, 7:
Magnification switching circuit, 8X, 8Y, 11: Amplifier, 9: Cathode ray tube, 10: Secondary electron detector, 12: Bright spot addition circuit, 1
3; Sample stage, 14X, 14Y: Pulse motor, 1
5: drive circuit, 16: control device, 17: rating signal generation circuit, 18: drive control circuit, 19 near-tub down counter, 20: register, 21: comparator, 22: 1/C circuit,
23: Input device, 23a, 23b, 23c, 24
d: push button switch, 23e: designated legitimate child, 23[
: Set switch, 24: Optical axis. 16-

Claims (2)

[Claims] (1) A means for two-dimensionally scanning an electron beam on a sample, and a display that scans in synchronization with the scanning of the electron beam and displays the sample image based on the supply of a detection signal accompanying the scanning of the electron beam. and a magnification switching means for switching the magnification by switching the scanning width of the electron beam, and a sample moving means for moving the sample, wherein the display means includes a mark for moving the field of view. and means for automatically moving the sample so that the position on the sample corresponding to the mark is displayed in the center of the screen based on a signal representing the magnification and a signal representing the position of the mark. A sample moving device such as a scanning electron microscope characterized by comprising: (2) A means for two-dimensionally scanning an electron beam on a sample, and a display that scans in synchronization with the scanning of the electron beam and displays a sample image based on the supply of a detection signal accompanying the scanning of the electron beam. and a magnification switching means for switching the magnification by switching the scanning width of the electron beam, and a sample moving means for moving the sample, wherein the display means includes a mark for moving the field of view. means for automatically lowering the magnification by controlling the magnification switching means when the position of the mark moves to the edge of the screen; a signal representing the magnification and the position of the mark; A sample moving device such as a scanning electron microscope, comprising: means for automatically moving the sample so that the position on the sample corresponding to the mark is displayed at the center of both surfaces based on a signal representing the mark. .