JPS6039749A - Scanning electron microscope - Google Patents

Abstract

PURPOSE:To enable any plane of a specimen to be observed without rotating the specimen by providing a double shaft inclining mechanism on which the specimen is loaded and display device for indicating a mark for representing the directions of said inclined shafts and forcing the specimen to automatically incline toward the mark. CONSTITUTION:X, Y moving tables 4X, 4Y for a parallel movement are mounted on a double shaft inclining table 1 rotatably mounted around axes 2X, 2Y, on which a specimen 5 is placed. A signal from a secondary electron detector 14 is supplied to a cathode ray tube 13 and displayed, while a bright line representing the directions of the inclination shafts of the inclining table 1 is displayed by means of a bright line display signal adder 10. The bright line is inclined to a horizontal axis by the operation of an input device 19, while the inclining table 1 is driven by an arithmetic operation control part 18 via a driving circuit 17, allowing the specimen 5 to make coincidence with the bright line as well as the specimen to be inclined. Accordingly, the specimen 5 can be inclined only with the rotation of a mark on a screen to permit any plane to be observed, allowing the operatability of the captioned electron microscope to be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scanning electron microscope having a mechanism for tilting a sample.

A conventional scanning electron microscope has a configuration in which an XY movement mechanism is placed on a uniaxial tilting mechanism, a sample rotation mechanism is placed on this XY movement mechanism, and a sample is placed on this sample rotation mechanism. It has a sample device.

Therefore, for example, when a cathode ray tube displays a highly uneven sample as shown in Figure 1(a), it is difficult to observe the shaded surface shown by A in the same figure from a more direct view. When doing this, first rotate the sample using the sample rotation mechanism so that the surface is as shown in Figure 1(b).
After making it parallel to the direction of the tilt axis of 1'31, -
The specimen is tilted by an axial tilting mechanism so that the electron beam is irradiated from the front onto the surface A, thereby displaying an image as shown in FIG. 1(C). However, when selecting an operating integrated circuit element as a sample and covering it for observation, the integrated circuit element is connected to, for example, wiring for supplying current and covering it, so if the sample is rotated by the rotation mechanism, The present invention solves these conventional drawbacks and allows the sample to be viewed on a desired surface without rotating the sample. The purpose is to provide a scanning electron microscope that allows easy observation of

[Structure of the Invention] The present invention scans a finely focused electron beam two-dimensionally on a sample, and guides a detection signal accompanying the scanning to a display device that is scanned in synchronization with the scanning to display a sample image. The display device includes: a biaxial tilting mechanism on which the sample is placed; a means for displaying a mark indicating the direction of the tilt axis when tilting the sample on the display device; and a control means for tilting the sample in the direction of the tilt axis indicated by the mark by controlling the drive of the two-axis tilt mechanism. It is characterized by

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

FIG. 2 shows an embodiment of the present invention.
is a two-axis sample tilting table mounted rotatably around a first axis 2X and a second axis 2Y.

3X and 3Y are step motors for rotating the sample tilting table 1 around the axes 2X and 2Y, respectively. An X-movement table 4x for moving the sample in parallel along the axis 2X is mounted on the sample tilting table 1, and an X-movement table 4x for moving the sample along the axis 2Y is further placed on the X-movement table 4X. A Y moving table 4Y is placed thereon. Although these moving tables 4X and 4Y are not shown, they can be moved by a predetermined amount by a step motor.A sample 5 is placed on the Y moving table 4Y. 7 is a focusing lens for focusing the electron beam EB generated from the electron gun 6, and is focused onto the sample 5 by an objective lens 8. 9 is a focusing lens for focusing the electron beam EB generated from the electron gun 6. 9 is a focusing lens for focusing the electron beam EB generated from the electron gun 6. This deflector 9 is supplied with a scanning signal from a scanning signal generation circuit 11 via an amplifier 10.The scanning signal from the scanning signal generation circuit 11 is supplied to the deflector 9 via an amplifier 12 to deflect the cathode ray tube 13. The cathode ray tube 13 is scanned in synchronization with the scanning of the electron beam EB.14
is a secondary electron detector, and the output signal from the secondary electron detector 14 is amplified in an amplifier 15 and then supplied to the cathode ray tube 13 as a luminance signal via a luminance line display signal addition circuit 16. . This bright line display signal addition circuit 1
6 is a circuit for creating a signal for displaying a bright line G as shown in FIG. 3 on the screen of the cathode ray tube 13 and adding it to the image signal from the detector 14. A drive circuit 17 generates a drive signal for rotating the step motors 2X, 2'Y based on an output signal from an arithmetic control section 18, which will be described later. Reference numeral 19 denotes a heir 19a for indicating the angle θ of the emission line G displayed on the cathode ray tube 13 with respect to the horizontal scanning line, and a unit step angle rotation of the sample 5 in the positive direction around the axis indicated by the emission line G. An instruction button 19b+ for folding and an instruction button 19b- for rotating in the negative direction about the same axis are provided.

The output signal from the input device 19 is supplied to the arithmetic control section 18, and the arithmetic control section 18 creates an angle θ in the cathode ray tube 13 with respect to the horizontal scanning line based on the signal from the input device 19. to generate a bright line display signal for displaying the bright line G, and to rotate the sample 5 around the axis corresponding to the bright line G by the angle specified by the instruction button 19b- or 19b-. The step motor 3
X.

3. Calculate the rotation angle of Y, and this calculated angle (P,
A control signal for rotating these step motors 3X, 3Y is generated and supplied to the drive circuit 17.

Reference numeral 20 denotes an auxiliary lens with small inductance, and an excitation signal is supplied to this auxiliary lens 20 from a dynamic focus circuit 22 via an amplifier 21. The dynamic focus circuit 22 includes the scanning signal generation circuit 1.
In synchronization with the scanning from 1, an IC signal and a signal representing the inclination direction and inclination angle of the surface of the sample Fi 15 are supplied from the arithmetic control unit 18, and the circuit 22 excites the auxiliary lens 20 based on these signals. The intensity is changed in synchronization with the scanning of the electron beam, and as the electron beam scans, the electron beam EB always
The objective lens 8, which is excited with a fixed excitation current, is compensated for so that the object is focused on the plane of the object.

Next, the operation will be explained by taking as an example a case where a surface A in a shadow part of a display image as shown in FIG. 3(a) is to be observed from the front.

When a scanning signal is supplied from the scanning signal generation circuit 11 to the deflector 9 and the cathode ray tube 13, the electron beam EB scans the sample 5,
Based on the detection signal obtained with this scanning, an image of the sample 5 as shown in FIG. 3<a) is displayed on the cathode ray tube 13. A bright line G indicating the direction of the tilt axis is also displayed. In a standard state, if the sample tilting table 1 rotates around an axis shown in the horizontal direction on the display screen, the bright line G is displayed in the horizontal direction in the initial state. In order to observe the surface indicated by A in Fig. 3(a) from the front, the specimen 5 must be rotated around the axis indicated by the dashed line in Fig. 3(a), so the operator must input Rotate the heir 19a of the device 19. As a result,
Since the signal supplied from the calculation control unit 18 to the bright line display signal addition circuit 16 changes, the bright line display signal generated from the bright line display signal addition circuit 16 also changes, and the angle of the displayed bright line G with respect to the horizontal line changes. θ keeps changing. Therefore, while observing the movement of this bright line G, we observed that this bright line G is
) until it matches the direction indicated by the dashed-dotted line 14, as shown in FIG. 3(b). Therefore, when the instruction button 19b+ of the input device 19 is pressed next, a signal is sent to the input device 19 instructing the sample tilting table 1 to rotate in the positive direction by a unit angle about the direction of the bright line G.
The signal is supplied to the calculation control section 18. The arithmetic control unit 18 performs the instructed rotation based on a signal from the input device 19 representing the angle θ of the bright line G with respect to the horizontal direction and a signal representing whether the rotation is positive or negative. The rotation angles α and β of the sample tilting table 1 around the axes 2X and 2Y necessary for this are calculated, and a drive signal is supplied to the step motor drive circuit 17 in order to rotate the sample tilting table 1 by these angles. By supplying such a drive signal, the step motor 3X.

3Y rotates, so that the surface A of the sample displayed on the cathode ray tube 13 faces upward by a unit angle. Therefore, by pressing the button 19b+ several times while observing the cathode ray tube screen, surface A gradually moves upward, and finally, as shown in FIG. can be displayed.

The embodiment described above is only one embodiment of the present invention, and other embodiments may be adopted.

For example, in the above-described lc embodiment, the mark indicates the direction of the tilt axis, but it may also indicate the tilt direction (that is, the direction perpendicular to the tilt axis).

Further, although a bright line is used as the mark, the direction of the tilt axis may be indicated not only by the bright line but also by a difference in color or contrast.

[Effect] As is clear from the above explanation, in the apparatus based on the present invention, the sample is placed in the first. By tilting around the second axis, it is possible to observe any surface of the sample without having to rotate the sample using a rotating device, and there is no fear of damaging semiconductor samples connected to lead wires during operation. can be observed.

In addition, a mark indicating the direction of the tilt axis when tilting the sample is displayed on the screen, and by simply rotating this mark on the screen, the sample can be automatically tilted in the direction indicated by this mark, making operation easier. It's extremely easy.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the drawbacks of the conventional device, Fig. 2 is a diagram for showing an embodiment of the present invention, and Fig. 3 is a diagram for explaining the operation of the embodiment of the device shown in Fig. 2. FIG. 2 is a diagram for explaining a display example of a cathode ray tube for displaying images. 1: Two-axis sample tilt table, 2X, 2Y: I tilt (If, 3X,
3Y varnish-j7 motor, 4X, 4. Y: sample moving table,
5: Sample, 6: Electron gun, 7: Focusing lens, 8: Objective lens, 9: Deflector, 11: Scanning signal generation circuit, 13: Cathode ray tube, 14: Secondary electron detector, 16: Bright spot display signal Addition circuit, 17: Drive circuit, 18: Arithmetic control unit, 19: Input device, G: Bright line. Figure 1 (c) Figure 3 (c)

Claims (1)

[Claims] In a device that displays a sample image by scanning a finely focused electron beam two-dimensionally on a sample and guiding a detection signal accompanying the scanning to a display device that is scanned by +y1 in the same manner as the scanning, the device displays a sample image. a biaxial tilting mechanism on which the specimen is placed; a means for displaying a mark indicating the direction of the tilting axis when tilting the sample on the display device; and a means for arbitrarily changing the direction of the tilting axis indicated by the mark. and control means for tilting the sample in the direction of the tilt axis indicated by the mark by controlling the driving of the biaxial tilt mechanism.