JPH01304647A - Reflection electron detector - Google Patents

Abstract

PURPOSE:To easily and speedily display an image excellent in an arbitral direction by processing two reflection electron signals integrated by modes synchronized by a signal integrating unit, and displaying them as an image, in correspondence with the rotation of the scanning/display direct ion of electron beam. CONSTITUTION:In the case of image generation by a differential signal, components 1'-6' composing a reflection electron detector 1 are connected to switch part 12-1 after they passed through an amplifier 11, selected arbitrarily and input to amplifiers 12-1, 12-3. An arbitral combination of members 1'-6' is made. Namely, the switch 12-1 are switched to input the members 1'-3' to the amplifier 12-3 to generate an added signal B in correspondence with the scanning direction of electron beam, while members 4'-6' are input to the amplifier 12-2 to generate an added signal A. The difference in signal B is obtained from the signal A by means of a differential signal processing circuit 13-1, and the luminance is modulated according to the signal of which lower part is cut by means of a signal level selection circuit 13-2, thereby an image is displayed on a CRT.

Description

[Detailed Description of the Invention] [Summary] Regarding a backscattered electron detection device that detects backscattered electrons reflected from an electron-irradiated sample and displays an image, the backscattered electron detector is divided into a plurality of parts, and the electron beam and image display direction are By synthesizing the corresponding backscattered electron signals corresponding to the synchronized rotation of the A plurality of backscattered electron detectors are arranged in the vicinity of a sample scanned by an electron beam and divided into multiple parts around the axis of the electron beam, and backscattered electron signals detected by each of these plurality of backscattered electron detectors are used. Among them, a signal synthesizer that combines the backscattered electron signals separated into two in a direction almost perpendicular to the scanning direction of the electron beam, and a signal synthesizer that synchronizes the scanning direction in which the sample is scanned by the electron beam and the direction in which the image signal is displayed. and a scan rotation circuit that rotates the scanning direction and the display direction of the electron beam, and processes two reflected electron signals synthesized in a synchronized manner by the signal synthesizer in response to rotation of the scanning direction and the display direction of the electron beam. , and configure it to display as an image.

[Industrial application field]

The present invention relates to a backscattered electron detection device that detects backscattered electrons reflected from a sample irradiated with electrons and displays an image.

[Conventional technology]

Conventionally, in a scanning electron microscope, the backscattered electron detector is separated into two parts perpendicular to the scanning direction of the electron beam and placed on the left and right sides, so that each side detects the backscattered electrons reflected from the sample. . The composition image (
The signal is displayed as a sum signal), a concavo-convex image (difference signal), etc.

[Problem to be solved by the invention]

Conventional backscattered electron detectors were installed in two parts, so if you wanted to display an image scanned from any direction, you had to mechanically rotate the sample to match the scanning direction of the electron beam. Therefore, there was a problem that an image in a desired direction could not be displayed quickly.

The present invention divides a backscattered electron detector into a plurality of parts, synthesizes corresponding backscattered electron signals in response to synchronized rotation of the electron beam and image display direction, and processes and displays these signals. The purpose is to easily and quickly display high-quality backscattered electron images in any direction.

[Means to solve problems]

Means for solving the problem will be explained with reference to FIG.

In FIG. 1, a backscattered electron detector 1 detects backscattered electrons reflected from a sample 2, and is divided into a plurality of parts and arranged around the axis of an electron beam that scans the sample 2.

The scan rotation circuit 9 rotates the scanning direction of the electron beam that scans the sample 2 and the direction of displaying an image on the CRT 16 in a synchronized manner.

The signal synthesizer 12 synthesizes reflected electrons in the left and right directions with respect to the scanning direction of the electron beam that scans the sample 2 so as to detect them.

[Effect]

As shown in FIG. 1, a backscattered electron detector 1 divided into a plurality of parts around the axis of an electron beam that irradiates a sample 2 is arranged as shown in the figure, and these backscattered electron detectors 1 The detected reflected electron signals are synthesized by a signal synthesizer 12 so as to detect two signals in the left and right directions of the electron beam in response to rotation of the scanning direction by a scan rotation circuit 9, and the synthesized reflected electron signals are detected by a signal synthesizer 12. The signal is processed (for example, by calculating a difference) and displayed as an image.

Therefore, the scan rotation circuit 9
Corresponding to the synchronized rotation of the scanning direction of the electron beam that scans the CRT 16 and the display direction of the CRT 16, the signal synthesizer 12 constantly detects reflected electron signals in the left and right directions with respect to the scanning direction. By performing signal processing on the combined backscattered electron signals and displaying them as an image, it becomes possible to quickly display a high-quality image based on the backscattered electron signals when the sample 2 is scanned in any direction.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be explained in detail using FIGS. 1 to 5.

In FIG. 1, a backscattered electron detector 1 is a P-N JUNCTTON that detects backscattered electrons reflected from a sample 2.
(semiconductor detector), etc., and as mentioned above, it is divided into a plurality of parts around the axis of the electron beam and arranged in the vicinity of the sample 2 as shown in the figure. In this example, 6 axially symmetrical
An example of division will be specifically explained below.

Sample 2 is intended for displaying and observing images based on backscattered electrons.

The electron gun 3 emits electrons.

The converging lens 4 converges the electrons (electron beam) emitted from the electron gun 3.

The deflection coil 5 scans an electron beam (electron probe) over the sample 2 in the H direction and the V direction.

The objective lens 6 forms an image of the electron beam on the sample 2.

The deflection switch 7 instructs switching of the direction of the electron beam that scans the sample 2.

The scanning signal generator (H, V) 8 generates a scanning signal for scanning the sample 2 in the horizontal direction (H) and vertical direction (V) with an electron beam.

Note that the CRT 16 is also scanned in synchronization with this scanning signal (H, V). As a result, the image on the CRT 1, 6 does not rotate even if the scanning direction in which the sample 2 is scanned is rotated.

The scan rotation circuit 9 includes a scan signal generator (H
, V) 8 to an angle instructed by the deflection switch 7, for example, as shown in FIG. 3(A) or FIG. 5, which will be described later.

The magnification drive setting section (H, V) 10 controls the width (H, V) of the electron beam that scans the sample 2 and sets the magnification of the backscattered electron image displayed on the CRT 16.

The amplifier 1) amplifies the backscattered electron signals detected by the plurality of backscattered electron detectors 1, respectively.

The signal combiner 12 combines reflected quantum signals detected by the plurality of backscattered electron detectors 1 and amplified by the amplifier 1). In this synthesis, as shown in FIG. 3, which will be described later, two reflected electron signals are generated in the left and right directions with respect to the scanning direction.

The signal processing circuit 13 performs signal processing such as calculating the sum and difference of the two reflected electron signals combined by the signal synthesizer 12.

The result of this signal processing is displayed on the CRT 16 as a composition image (an image based on a sum signal), a concave-convex image (an image based on a difference signal), etc., by subjecting it to luminance modulation, for example.

The CRT deflection drive circuit 14 drives the CRT deflection coil 15 to display an image on the CRT 16.

Next, using FIG. 2, a specific example will be described in which an image (concave-convex image) is generated by a difference signal by the backscattered electron detector 1, signal synthesizer 12, and signal processing circuit 13 shown in FIG.

In FIG. 2, the backscattered electron detector 1 is divided into six parts with the center of the electron beam as an axis, as shown by (1) to (2).

These backscattered electron detectors 1 through 1 pass through an amplifier 1) as shown in the figure, and then pass through a switch 12.
-1 as shown in the figure, and an arbitrary one is selected and input to the amplifiers 12-2 and 12-3. This results in
Any combination of ■ or ■ constituting the backscattered electron detector 1, for example, by switching the switch 12-1 as shown by the solid line in the figure in correspondence with the scanning direction of the electron beam, inputting ■ or ■ to the amplifier 12-3. The summed signal B is generated, and the summed signal A is generated by inputting (1) to (2) to the amplifier 12-2. Then, a difference signal processing circuit 13-1 converts the signal B from the generated signal A into a difference signal (A-B).
Then, the signal level selection circuit 13-2 modulates the brightness with the signal resulting from canting the lower part as shown in FIG. It is possible to display images by reflected electrons as shown in FIGS. 5(a) to 2).

Note that the difference (A
-B) may be displayed on the CRT 16 as is.

An example of the relationship between the deflection direction and the backscattered electron detector 1 will be explained using FIG.

FIG. 3(a) shows the scanning direction in which the sample 2 is scanned by the electron beam, and FIG. 3(b) shows an example of a switch pattern for synthesizing the backscattered electron signals detected by the backscattered electron detector 1 at that time.

First, when scanning in the horizontal direction (horizontal scanning, H) as shown in Figure 3 (a) N = 1 (θ = 0°), as shown in Figure 3 (b) N = 1 in the switch pattern example Like, ■ or ■
The backscattered electron signals detected by the backscattered electron detector (Figure 2 backscattered electron detector) l are combined into one by the switch 12-1 and amplifier 12-3 in Figure 2, and the backscattered electron detectors The reflected electron signal detected by the switch 12-1 and the amplifier 12-2 in FIG.
I am trying to synthesize it into Similarly, Figure 3 (a) N
=2 and N=3 as well, the backscattered electron signals detected by the backscattered electron detector 1 as shown in FIG. 3(b) are each combined into one.

As described above, as shown in FIG. 3(A), it is possible to obtain backscattered electron signals that are separated into two left and right in a direction perpendicular to the electrically rotated scanning direction. Therefore,
Unlike the conventional method, there is no need to rotate the sample 2 (it is possible to quickly and easily detect a backscattered electron signal at a desired rotation angle and display a concavo-convex image, etc.).

Next, the operation for displaying a concavo-convex image of the hemispherical sample 2 will be specifically explained using FIGS. 4 and 5.

FIG. 4(A) shows a hemispherical sample 2. This represents that the sample 2 of the illustrated hemisphere is mounted on the sample stage of the scanning electron microscope shown in FIG.

FIG. 4(b) shows a state in which the hemispherical sample 2 shown in FIG. 4(a) is scanned from side A to side B by an electron beam.

FIG. 4(c) shows a backscattered electron signal detected by the backscattered electron detector 1 placed on the A side. This is shown in Figure 4 (
Corresponding to the scanning of (b), the backscattered electron detector (Fig. 2 ■ to ■) 1, amplifier 1), switch 12- placed on the A side
This is a backscattered electron signal on the A side detected by the L amplifier 12-2.

The part marked ■ in the figure is the side where the hemispherical sample 2 faces the backscattered electron detector l, so it is detected as a large peak, and the part marked ■ in the figure is the side where the hemispherical sample 2 faces the direction opposite to the backscattered electron detector l. Since it is a surface, it is detected as a negative peak.

FIG. 4(d) shows a backscattered electron signal detected by the backscattered electron detector 1 on the B side. 1), the switch 12-1, and the amplifier 12-3. In the part marked ■ in the figure, the hemispherical sample 2 faces the opposite direction of the backscattered electron detector 1, so it is detected as a negative peak. Since it is a surface facing in the direction of , it is detected as a large peak.

Figure 4 (E) shows the difference (A) obtained by subtracting the backscattered electron signal on the B side (Fig.
-B) is shown. An image displayed by modulating the brightness of this difference (A-B) on the CRT 16 is generally called a concavo-convex image, a topographic image, or the like.

Figure 4 (e) shows the difference (A-B) in Figure 4 (e).
As shown in the figure, "cant the lower part", the peak in the negative direction is cut.

As a result, the concave portions of the concavo-convex image are canted, and the convex portions are extracted.

Next, FIG. 5(a) shows the difference (A-B) shown in FIG. It is displayed with brightness modulation on the top. The black part is the bright part.

FIG. 5(b) shows the case where the scanning direction of the electron beam scanning the hemispherical sample 2 and the display direction of displaying the image on the CRT 16 are each rotated 120' counterclockwise.

FIG. 5(c) shows the case of rotation by 240° counterclockwise.

Figure 5 (d) is 3 from Figure 5 (a) to Figure 5 (c).
The two images are added together (A + A I□. 10 AX 4 degrees) and displayed.

As described above, of the concavo-convex images of the hemispherical sample 2 viewed from the three directions, A direction, Al1° direction, and A14° direction shown in FIG.
Take out the convex part), and as shown in Figure 5 (d),
By superimposing and displaying on two screens, it becomes possible to display the hemispherical sample 2 in a so-called three-dimensional manner.

〔Effect of the invention〕

As explained above, the scanning direction of the electron beam that scans the sample 2 by the scan rotation circuit 9 and the C
Corresponding to the synchronized rotation of the display direction of the RT 16, the signal synthesizer 12 constantly detects backscattered electron signals in the left and right directions and automatically combines them, so to speak, and the combined backscattered electron signals are subjected to signal processing. Since a configuration in which images are displayed is adopted, a high-quality image based on reflected electron signals when the sample 2 is scanned in an arbitrary direction can be quickly displayed. Furthermore, by superimposing and displaying backscattered electron signals detected from a plurality of directions with respect to the sample 2, it becomes possible to display the sample 2 three-dimensionally.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of one embodiment of the present invention, Fig. 2 is an example of the main circuitry related to the present invention, Fig. 3 is an explanatory diagram of the relationship between the deflection direction and the backscattered electron detector, and Fig. 4 is differential signal processing. The explanatory diagram, FIG. 5, shows an example of image display after differential signal processing. In the figure, l is a backscattered electron detector, 2 is a sample, 9 is a scan roti 292 circuit, 1) is an amplifier, 12 is a signal synthesizer,
13 represents a signal processing circuit, and 16 represents a CRT. Station size

Claims (2)

[Claims] (1) In a backscattered electron detection device that detects backscattered electrons reflected from a sample irradiated with electrons and displays an image, the backscattered electron detector is arranged near the sample scanned by the electron beam and divided into multiple parts around the axis of the electron beam. of the backscattered electron signals detected by these multiple backscattered electron detectors (1), which are separated into two in a direction approximately perpendicular to the scanning direction of the electron beam. It is equipped with a signal synthesizer (12) that synthesizes each backscattered electron signal, and a scan rotation circuit (9) that synchronizes and rotates the scanning direction in which the sample is scanned by the electron beam and the direction in which the image signal is displayed. In response to rotating the scanning direction and display direction of the signal synthesizer (12),
A backscattered electron detection device characterized in that it is configured to signal-process two backscattered electron signals synthesized in a synchronized manner by and display them as an image. (2) In response to rotating the scanning direction of the electron beam and the image display direction, the difference between the two backscattered electron signals synthesized in a synchronous manner by the signal synthesizer (12) is displayed as an image. The backscattered electron detection device according to item (1), characterized in that it is configured as follows.