JPS62223961A - Scanning type reflecting electron diffraction microscope device - Google Patents

Abstract

PURPOSE:To obtain a reflecting diffraction image from a specific analyzing spot or the diffraction spot intensity without stopping the observation, by fixing the radiation of primary electron beams at a specific analyzing spot every time when the X direction scanning is over, and gaining the signal only at such a time. CONSTITUTION:Every time when a line scanning in the X direction is over, a preset current value is made to flow only in DELTAt time to a deflection coil in the X direction, and a preset current value is made to flow in the DELTAt time also to a deflection coil in the Y direction. Just after that, the deflecting current in Y direction is converted in steps, then the line scanning in X direction is carried out again, and such operations are repeated. Therefore, beams 4 can be fixed the radiation onto a specific analyzing spot on a sample 7 without stopping the scanning of the primary electron beams 4. And a control signal from a converting circuit 22 is received at a two-dimension image display device 21, and only the reflecting diffraction image from the specific analyzing spot is displayed there. Furthermore, the signal is picked up in parallel by a control circuit 23, and the intensity variation of a specific diffraction spot obtained from the specific analyzing spot is examined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a scanning-type backscattered electron diffraction microscope used for analyzing the crystallinity of a sample surface.

[Conventional technology]

The basic setup of a conventional scanning backscattered electron diffraction microscope device is shown in FIG. 4. The device in FIG. 4 operates as follows. acceleration?
! ! A primary electron beam 4 emitted from an electron gun 2 having a source 1 is focused by a converging lens 3 onto the surface of a sample 7 located within a vacuum vessel 6 . The primary electron beam deflection coil group 5 is operated by the scanning power supply 16 to scan the primary electron beam 4 over the surface of the sample 7. At this time, as shown in Figure 5,
A sawtooth current is passed through the X-direction deflection coil in the primary electron beam deflection coil group 5, and the primary electron beam 4 is scanned in a line in the X direction. Immediately after this one linear scan is completed, a stepwise increasing current is applied to the Y-direction deflection coil to slightly deflect the primary electron beam As 4 in the Y-direction. By repeating these operations, the XY
The primary electron beats 4 scan the plane. The absorption current signal or secondary electron signal of the sample 7 obtained at that time is converted into a brightness modulation signal of a cathode ray tube (hereinafter abbreviated as CRT) 15 to obtain a scanning electron microscopic image of the sample 7 on the CRT 15. The location on the sample 7 to be analyzed is selected from this image. A reflected diffraction line 8 obtained by fixedly irradiating this analysis point with a primary electron beam is observed as a reflected diffraction image on a fluorescent screen 9 through a viewing window 1o. By analyzing this reflection diffraction image, it becomes possible to analyze the crystalline state (the arrangement state of atoms constituting the surface portion of the sample 7) at any location on the surface of the sample 7. In addition, a translucent reflector 19° optical lens 11. A specific diffraction spot in the reflected diffraction image is selected using an aperture 12, guided to a photoelectric conversion element (for example, a photomultiplier tube) 14 through an optical fiber 13, and converted into an electric signal, and this electric signal is converted into a primary electron beam 4. A diffraction microscopic image is obtained on the CRT 15 by changing the brightness modulation signal of the CRT 15 in synchronization with the scanning. The crystal distribution on the surface of sample 7 can be seen from this diffraction microscopic image. Furthermore, by depositing the substance 18 on the sample 7 with the vapor deposition gun 17, the crystal growth process of the substance 18 on the sample 7 can be observed on the spot using the above-mentioned diffraction microscopic image. In addition, related devices of this type include, for example, [Japanese
Journal of Applied Physics (Jap
anese Journal of Applied P
hysics) Volume 23 (1984) No. 913-920
Pages are mentioned.

[Problem that the invention seeks to solve]

In this way, the scanning backscattered electron diffraction microscope is an effective device for microscopically investigating the crystalline state of the sample surface and the crystal growth process of the substance 18 on the sample 7, but conventional devices have the following disadvantages. There was a problem. Dynamic process on sample 7,
For example, when investigating the crystal growth process of the substance 18, it is necessary to observe the crystal growth process as an image using the diffraction microscopic image, and at the same time, it is necessary to know the change in the reflection diffraction image from a specific analysis point, that is, the change in the crystal state. is also extremely important. A diffraction microscopic image! During analysis, the primary electron beam ls 4 is scanning over the sample 7, so changes in the reflection diffraction image from a specific analysis point cannot be known. In addition, when investigating changes in the reflection diffraction image from a specific analysis point, the primary electron beam 4 is fixedly irradiated onto the sample 7, so the diffraction microscopic image can be measured using I! There was a problem that J could not be detected.

An object of the present invention is to solve the above-mentioned problems in the prior art, and to obtain the above-mentioned reflection diffraction image or diffraction spot intensity from a specific analysis point without interrupting the observation of the scanning electron microscopic image. An object of the present invention is to provide a scanning-type reflection electron diffraction microscope device.

[Means for solving problems]

The above purpose is to first scan the primary electron beam on the sample in the X direction in a line shape, then scan in the Y direction in a step shape, and repeat this to obtain a scanning electron microscope image. This is achieved by fixedly irradiating a specific analysis point with the primary electron beam 21 each time the analysis is completed, and acquiring a signal only at that time.

[Effect]

In the above invention, the time during which the primary electron beam is fixedly irradiating a specific analysis point on the sample is the time between one X-direction scan and the next X-direction scan, that is, on the order of milliseconds, and is substantially The reflection diffraction image or the change in diffraction spot intensity from a specific analysis point can be obtained without interrupting the observation of the scanning electron microscopic image.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. J and FIG. 2. In FIG. 1, 20 is a television camera that monitors the reflected diffraction image on the fluorescent screen 9, 21 is a two-dimensional image display device that temporarily accumulates and displays this reflected diffraction image, and 22 is a device that completes one X-direction scan. A switching circuit 23 controls the fixed irradiation of the primary electron beam t-, 4 to a specific analysis point for each analysis point. This is a control circuit for distributing the data, and the rest is the same as the conventional example shown in FIG. Switching circuit 2
In step 2, the operations shown in FIG. 2 are performed. First, a specific analysis point at which the reflection diffraction image is to be obtained is determined on the scanning electron microscope image, for example, in a fixed irradiation mode. At this time, specific deflection currents are flowing through the X-direction and Y-direction deflection coils of the primary electron beam deflection coil group 5, and these deflection current values correspond to specific analysis points.

Therefore, these deflection current values are memorized and one
Every time line scanning in the direction is completed, the set current value is applied to the X-direction deflection coil for a time period of Δt, and at the same time, the set current value is applied to the Y-direction deflection coil for a time period of Δt. Immediately after this, the deflection current in the Y direction is changed stepwise, and the line scanning in the X direction is performed again, and this operation is repeated.By performing such an operation, the scanning of the primary electron beam 114 is substantially interrupted. 1% 4 of primary electron beams can be fixedly irradiated onto a specific analysis point on the sample 7.

However, at this time, since the television camera 20 monitors the reflected diffraction image during the entire process of the above operation, the two-dimensional image display device 21 receives a control signal from the switching circuit 22, and the primary electron beam 1z4 is fixedly irradiated. By accumulating and storing signals only when the analysis is being performed, only the reflection diffraction image from a specific analysis point is displayed. Also, the gate circuit 23
, a control signal is received from the switching circuit 22, and only when the primary electron beats 4 are scanning over the sample 7 (i
By sending the signal to the CRTL 5, it is possible to obtain the above-mentioned diffraction microscopic image from which unnecessary signals accompanying the above-mentioned fixed irradiation have been removed. Furthermore, by acquiring signals in parallel when the primary electron beam 4 is fixedly irradiated by the control circuit 23, it is also possible to examine the intensity change of a specific diffraction spot obtained from the above-mentioned analysis point.

FIG. 3 is a block diagram showing another embodiment of the present invention. Here, an optical switching mechanism 24 (for example, a Pockels cell) that allows light to pass when a specific potential is applied is provided in front of the television camera 20, and a control signal from a switching circuit 22 causes the primary electron beam 4 to conduct a specific analysis on the sample 7. Only when a fixed point is irradiated, light is allowed to pass through and the reflected diffraction image is observed. Two-dimensional image display device 2 for observing the reflection diffraction image at this time
1 can be an ordinary television receiver.

〔Effect of the invention〕

As described above, the apparatus according to the present invention fixedly irradiates a specific analysis point to be measured with a primary electron beam every time one line scan in the X direction is completed, and acquires a signal only at that time. Dynamic processes on the sample surface, such as the crystal growth process of materials, can be observed while observing scanning electron microscopy images.
It also has the extremely excellent advantage of being able to examine changes in the crystal state at a specific analysis point from a reflection diffraction image from that point.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal sectional view showing the configuration of an embodiment of the present invention;
FIG. 2 is a characteristic diagram showing the behavior of the deflection current in this embodiment, and FIG. 3 is a schematic vertical cross-sectional view showing the configuration of another embodiment, f5
Figure 4 is a schematic vertical sectional view showing the 5th configuration of the conventional device, and the 5th
The figure is a characteristic diagram showing the behavior of deflection current in a conventional device. DESCRIPTION OF SYMBOLS 1... Accelerating power supply, 2... Electron gun, 3... Converging lens, 4... Primary electron beam, 5... Deflection coil group for primary electron beam, 6... Vacuum vessel, 7... ...Sample, 8
...Reflection diffraction line, 9... Fluorescent screen, 10... Peephole, 11... Optical lens, 12... Aperture, 1
3... Optical fiber, 14... Photoelectric conversion element, 15.
...lI triode ray tube, 16...scanning power source, 17...evaporation gun, 18...substance, 19...semi-transparent reflector, 20
...TV camera, 2J...Two-dimensional image display device,
22...Switching circuit, 23...Control circuit 1, -\

Claims (1)

[Claims] 1. A primary electron beam is irradiated onto a predetermined area on the sample surface at a predetermined angle through a converging lens and a deflection system, and a diffraction image is formed on a fluorescent screen by reflected electron diffraction rays reflected from the sample surface. In a scanning electron diffraction microscope device that obtains a scanning electron microscopic image by converting the generation from a specific diffraction spot in a reflection diffraction image into an electrical signal using a photoelectric conversion element, a primary electron beam is first converted into a line in the X direction. scan,
When obtaining a scanning electron microscope image by scanning stepwise in the Y direction after completing one X direction scan and repeating the process, the primary electron beam is applied to a specific analysis point each time one X direction scan is completed. By fixedly irradiating and acquiring the signal only at that time, it is possible to obtain the reflected diffraction image or diffraction spot intensity from a specific analysis point without interrupting the observation of the scanning electron microscopic image. A scanning backscattered electron diffraction microscope device.