JPH0360150B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a scanning electron microscope capable of observing a scanning image by tilting it in any direction.

[Prior art] Scanning electron microscopes have the advantage of being able to obtain clear images even if the surface of the observation sample is extremely uneven, but in order to fully utilize this advantage, it is necessary to It is necessary to be able to tilt the surface in the direction of , so that the portion corresponding to the shadow of the unevenness can be observed. In order to meet this demand, scanning electron microscopes have conventionally included a sample device as shown in FIG. That is, the side wall 1 of the sample chamber
A tilting mechanism 2 is attached to the tilting mechanism 2, and its tilting axis U is fixed. At the top of the tilting mechanism 2,
A rotating mechanism 4 is placed on top of the XY moving mechanism 3, and the observation sample 5 is attached to the rotating mechanism 4 via a holder. Using such a sample apparatus, when the sample surface with respect to the sample irradiation electron beam 6 is tilted by the tilt mechanism 2 and then the sample is rotated by the sample rotation mechanism 4, the tilt axis U rotates with respect to the sample. , b, c, screen C
You can change the part corresponding to the shadow of the unevenness displayed on the screen.

Conventionally, the amount of rotation in such a device can be adjusted using a push-button switch, in which the sample continues to rotate only while the knob is pressed, and the rotation stops when the button is stopped, and the operator observes the screen. I was operating it while doing so. However, since the rotation of the sample is mechanically driven by a motor, the response to knob or button operations is poor, and unless the operator is an experienced operator, it is difficult to rotate the sample to the desired angle with a single operation. I couldn't do it. Therefore, the goal is usually reached through trial and error by repeatedly starting and stopping the rotation, but it takes a considerable amount of time to reach the goal, especially since it is not possible to start and stop the rotation suddenly. Ta.

[Object of the Invention] The present invention has been made to solve these conventional drawbacks, and an object of the present invention is to provide a scanning electron microscope that can rotate a sample to a desired angle easily and in a short time. It is something.

[Structure of the Invention] The present invention includes a sample tilting mechanism, a sample moving mechanism, a sample rotating mechanism, a means for two-dimensionally scanning an electron beam on a sample, and a means for two-dimensionally scanning an electron beam on a sample, and a means for scanning an electron beam in synchronization with the scanning of the electron beam. An apparatus comprising a display means for displaying a sample image based on a detection signal obtained in conjunction with scanning of an electron beam, a means for displaying a mark on a display screen of the display means, and a means for arbitrarily rotating the mark. control means for rotating the sample rotation mechanism by φ based on a signal representing the angle φ from the reference mark of the mark; The present invention is characterized by comprising means for moving the sample by the sample moving mechanism before and after or together with the rotation.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 3 schematically shows an embodiment of the present invention, in which the same components as in FIG. 1 are given the same numbers. In the figure, 7 is an electron gun, 8 is a focusing lens for focusing the electron beam 6, 9X, 9
Y is a deflection coil. A sawtooth scanning signal is supplied from a scanning signal generating circuit 10 to the deflection coils 9X and 9Y. 11X and 11Y are amplifiers. The scanning signal from the scanning signal generating circuit 10 is also supplied to the deflection coil D of the cathode ray tube 12, and the cathode ray tube 12 is scanned in synchronization with the electron beam 6. A secondary electron detector 13 is arranged to detect secondary electrons generated from the sample 5 by irradiation with the electron beam 6. The signal from the detector 13 is supplied to the cathode of the cathode ray tube 12 via an amplifier 14 and a bright line signal addition circuit 15. 16I and 16R are pulse motors for driving the tilting mechanism 2 and rotation mechanism 4, respectively, and 16X and 16Y are pulse motors for driving the X and Y moving mechanisms. These motors 16I, 16R, 16X, 16Y are connected to motor drive circuits 17I, 17R, 17X, 1, respectively.
It rotates by the supply of drive pulses generated from 7Y. Generation of drive pulses in each of these drive circuits is controlled by control signals from a control device 18. This control device 18 has a storage section, a calculation section, etc., and not only controls each drive circuit, but also controls the screen of the cathode ray tube 12 based on a signal synchronized with scanning supplied from the scanning signal generation circuit 10. A bright line display signal for displaying a bright line Q as shown in FIG. 4 is generated. This bright line display signal is superimposed on the signal from the detector 13 in the bright line adding circuit 15 and is supplied to the cathode ray tube 12. An input device 19 is connected to the control device 18 . This input device 19
As shown in FIG. 5, there is a bright line rotation knob 19a for rotating the bright line Q displayed on the screen of the cathode ray tube 12, and a bright line rotation knob 19a for rotating the bright line Q displayed on the screen of the cathode ray tube 12; Rotation command button 19b for commanding rotation to an angle of , tilt mechanism 2
A sample tilt knob 19c that specifies the tilt angle by
Buttons 19xa, 19xb, 19ya, 1 for moving the sample in the X and Y directions by the XY movement mechanism 3
9yb etc. are provided.

In such a configuration, when the electron beam 6 is scanned over the sample 5 using a scanning signal from the scanning signal generation circuit 10, a sample image is obtained on the cathode ray tube 12. In the initial state when the bright line circuit knob 19a is not operated, a horizontal bright line Q is displayed on the screen superimposed on the image as shown in FIG.
Therefore, while observing the sample image, the operator first operates the sample tilting knob 19c to tilt the sample 5 at a predetermined angle, for example θ ₀ , using the tilting mechanism 2, and moves the sample 5 by operating the buttons 19xa, 19xb, 19ya, and 19yb. The mechanism 3 moves the sample 5 to a predetermined position x ₁ , y ₁ . Therefore, while observing the image obtained as a result of such operations, the bright line rotation knob 19a of the input device 19 is operated to change the bright line display signal supplied from the control device 18. Rotate the bright line Q displayed on the screen around the center of the screen. By such rotation, the bright line Q is rotated by the rotation mechanism 4 until it overlaps with the image part that you want to display in the horizontal position of the screen, for example, to the bright line _Q1 in FIG. 4, and then the rotation command button 19b is rotated. The rotation mechanism 4 is operated to command the sample 5 to rotate. Assuming that the rotation angle of the bright line is φ, the control device 18 holds data representing this angle φ, and therefore, by operating the rotation command button 19b, the input device 19 instructs the control device to rotate the rotation mechanism 4. When the control device 18 sends a control signal to the drive circuit 17R, the pulse motor 16 is rotated by the angle φ. As a result, the part of the image that was displayed on the screen superimposed on the bright line Q ₁ is rotated by an angle φ. By the way, in many cases where the axis of rotation by the rotation mechanism 4 and the optical axis do not match, the movement mechanism 3
If _{sample 5 is} not moved _by Center R
As the sample 4 rotates around O', the field of view of the screen disappears. In order to prevent such a situation, the control device 18 stores the rotation center positions x ₀ , y ₀ and the optical axis positions x ₁ , y ₁ of the sample rotation device 4, and uses this stored data and the φ
Based on a signal representing , the moving mechanism 3 moves the sample 5 in the X and Y directions by lx, ly in the figure. As a result, when the rotation by the rotation mechanism 4 is completed, the part of the image that was displayed superimposed on the bright line Q ₁ before the rotation is displayed on the horizontal line on the screen of the cathode ray tube 12, and the field of view is A picture with no escape is displayed. As the sample 5 rotates, the bright line display signal generated from the control device 18 is automatically switched to a signal for horizontally displaying the bright line, so that the bright line returns to the horizontal bright line Q.

In the above-mentioned embodiment, the movement of the sample was not performed in synchronization with the rotation operation of the rotation mechanism to prevent the field of view from escaping due to rotation of the sample, but the rotation of the rotation mechanism in the X direction and By controlling the movement of the moving mechanism in accordance with the rotation of the rotating mechanism so as to cancel out the velocity component of the movement in the Y direction, it is possible to prevent the visual field from escaping not only at the end of the rotation but also during the entire rotation process. I can do it.

Furthermore, in the above embodiment, a bright line was used as a mark for specifying the rotation angle of the sample, but a cross-shaped mark may also be used, or half of the screen may be displayed with different brightness. By doing so, the bright line may be replaced.

[Effect] As described above, in the present invention, the mark displayed on the screen is rotated by an arbitrary angle, and the rotation mechanism 4 is automatically rotated by the angle of this mark. Since all angles can be changed with good responsiveness by electrical control, the sample can be rotated to a desired angle easily and in a short time.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the sample device of a scanning electron microscope, Fig. 2 is a diagram for explaining that the tilting shaft is rotated by rotation by a rotation mechanism, and Fig. 3 is an embodiment of the present invention. Figure 4 is a diagram to explain the change in the bright line displayed on the cathode ray tube, Figure 5 is a diagram to explain the input device, and Figure 6 is a diagram to explain the rotation of the sample. FIG. 1: side wall, 2: tilting mechanism, 3: moving mechanism, 4:
Rotation mechanism, 5: sample, 6: electron beam, 7: electron gun,
8: Focusing lens, 9X, 9Y: Deflection coil, 1
0: Scanning signal generation circuit, 12: Cathode ray tube, 13:
Secondary electron detector, 15: Bright line signal addition circuit, 16
I, 16R, 16X, 16Y: Pulse motor, 1
7I, 17R, 17X, 17Y: Drive circuit, 1
8: Control device, 19: Input device, 19a: Bright line rotation knob, 19b: Rotation command button, 19c: Sample tilt knob, 19xa, 19xb, 19ya, 19yb:
Sample moving knob, U: tilt axis, C: screen, Z: optical axis, Q, Q ₁ : emission line.

Claims (1)

[Claims] 1. A sample tilting mechanism, a sample moving mechanism, a sample rotating mechanism, a means for two-dimensionally scanning an electron beam on the sample, and a means for scanning in synchronization with the scanning of the electron beam and accompanying the scanning of the electron beam. a display means for displaying a sample image based on a detection signal obtained by the display means, a means for displaying a mark on a display screen of the display means, a means for arbitrarily rotating the mark;
control means for rotating the sample rotation mechanism by φ based on a signal representing the angle φ from the reference of the mark; A scanning electron microscope characterized in that the scanning electron microscope comprises means for moving the sample by the sample moving mechanism or at the same time as the rotation.