JP2004063468A - Scanning electron microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily find a field outside of a range of field. <P>SOLUTION: A sample 9 is scanned by an electron beam 2. A secondary electronic signal obtained from the sample 9 is detected by a detector 14a and/or a 14b, and an image of the sample is displayed on a first display surface area of an image display device 15 on the basis of the detection. The sample image is stored in a storage device 16 with a position of the image as an image for designating an observation position. The plurality of images of different positions may be stored. One of the stored images is selected and read out to be displayed on a second display surface area. When an interesting part of the displayed image for designating the observation position is selected, the sample 9 is horizontally moved to set the position of the part on a center of the first display face area, and an enlarged image of the interesting part is displayed on the first display surface area. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a scanning electron microscope that obtains an image of a sample by detecting an information signal that characterizes the sample and that is generated by scanning the sample with an electron beam.
[0002]
[Prior art]
In a scanning electron microscope, a specified position on the image is moved to a predetermined position, and an arbitrary image within the observation field of view is described as described in JP-B-54-78075 in order to obtain an enlarged image corresponding to the specified position. A technique is known in which a sample is moved to the center of an observation visual field by indicating the position of the sample with a display pointer.
[0003]
[Problems to be solved by the invention]
This technique is effective when the position to be magnified and observed is within the observation visual field. However, when the enlarged observation position is outside the field of view or outside the beam scanable area, an enlarged image corresponding to the position cannot be obtained.
[0004]
In general, when searching for a visual field, the search is often performed not only within the visual field but also outside the visual field range. For this reason, approximate positioning is performed on a magnification image that is effective for field-of-view search, and thereafter the magnification is gradually increased to determine the observation position and the observation magnification. In such a visual field searching method, since there is no marking function of an observation position, it is difficult to search for a position when observing the same position again.
[0005]
An object of the present invention is to provide a scanning electron microscope suitable for facilitating a search for a visual field outside a visual field range.
[0006]
[Means for Solving the Problems]
In order to achieve the object of the present invention, a scanning electron microscope according to the present invention includes a means for scanning a sample with an electron beam to generate an information signal characterizing the sample, and a means for detecting the generated information signal. Means for obtaining an observation image of the sample based on the detected information signal, means for storing the obtained observation image as an observation position designation image, and reading out the stored observation position designation image. Means, means for displaying the obtained observation image and the read-out observation position designation image on respective display surfaces, means for designating an observation position on the displayed observation position designation image, Means for displaying a designated observation position on the displayed observation position designation image as a position display pointer, and moving the position display pointer in accordance with the movement of the designated observation position, and the designated observation position Before Means for controlling the scanning position of the sample by the electron beam so as to move the observation image to a predetermined position on the display surface and display the observation image corresponding to the specified observation position on the display surface. There is a feature in that it includes.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic configuration diagram of one embodiment of a scanning electron microscope according to the present invention. Electron beam 2 emitted from cathode 1 is extracted by extraction voltage V1 applied between cathode 1 and extraction electrode 3, and accelerated by acceleration voltage Vacc applied between cathode 1 and acceleration electrode 4. The electron beam 2 is focused on a sample 9 on a sample stage 10 by focusing lenses 5 and 6 controlled by a lens control power supply 12 and an objective lens 8. The sample stage 10, that is, the sample 9 can be moved and rotated in the horizontal direction (X and Y directions) and the axial direction of the electron beam 2 (Z direction) by the sample stage drive unit 19. The scanning signal from the scanning power supply 26 is applied to a two-stage deflector composed of deflectors 7a and 7b via a magnification setting device 27, and therefore, the sample 9 is two-dimensionally scanned with the focused electron beam. Reference numeral 11 denotes an aperture.
[0008]
An information signal characterizing the sample 9, typically a secondary electron signal 13, is generated from the sample 9 by irradiation of the electron beam 2. The generated secondary electron signal 13 is detected by the signal detectors 14a and / or 14b. One or both of these detectors are used depending on the type of the sample, the height of the sample, and the like. The signal detected by the detectors 14a and / or 14b is introduced as a luminance modulation signal to an image display device 15 including a CRT. Although not shown in the drawing, the scanning of the CRT of the image display device 15 is synchronized with the scanning of the sample 9 by the electron beam 2, and therefore, an enlarged image (scanned image) of the sample 9 by the secondary electrons is displayed on the CRT in real time. Displayed with. The magnification of the magnified image can be arbitrarily set by a magnification setting device 27.
[0009]
FIG. 2 shows a flow of sample observation. First, an enlarged image of the sample 9 is displayed on the image display device 15 as described above (S1). When the enlarged image is designated by the stored image control unit 17 (S2), the designated enlarged image signal indicates the position of the enlarged image (actually, the center position of the enlarged image) on the sample (on the sample stage). (S3) together with the coordinate position). Of course, by executing the designation a plurality of times, a plurality of enlarged images at different positions on the sample can be stored in the storage device 16.
[0010]
FIG. 3 is a coordinate position map of the stored image on the sample stage, which may be displayed on the image display device 15 instead of an enlarged image of the sample, or may be displayed separately. In the figure, reference numeral 21 denotes the position of the stored image on the sample, which is displayed as a position display pointer. When one of the position pointers is selected and designated by the stored image controller 17, the stored image corresponding to the designated position is read out (S4), and the image display device 15 enlarges the sample obtained in real time. It is displayed simultaneously with the image (S5).
[0011]
FIG. 4 shows an enlarged image of the sample obtained in real time on the display surface area 22 of the image display device 15, and at the same time, an image read out by designation as an observation position designation image in a partial area 23 in the area. An example of the display is shown. In FIG. 4, reference numeral 28 denotes a position display pointer for displaying a position of a portion of the image to be magnified and observed. When the sample stage 10 is rotated, the observation position designating image is rotated accordingly. When the sample stage 10 is rotated and the observation position is moved by rotating the sample stage 10, the position display pointer 28 moves. It moves in accordance with its rotation direction and movement. In FIG. 4, the observation position designation image is displayed in a part of the display surface area 22, but may be displayed in another area or may be displayed alongside the enlarged image.
[0012]
When the position indicator 18 is operated to select and designate an interesting part in the image displayed in the area 23, that is, the observation position designating image, with the position display pointer 28 (S6), the position signal of the designated part is obtained. The data is read from the storage device 16 and supplied to the sample stage drive unit 19. Therefore, the sample stage 10, that is, the sample 9 is horizontally moved (so-called visual field movement) so that the position of the designated portion is automatically positioned at the center position of the display surface area 22 (S7), and designated. An enlarged image (observation image) of the portion that has been displayed is displayed in the display surface area 22, and the observation can be performed (S8). The magnification (magnification) of the image can be freely set by the magnification setting device 27.
[0013]
As can be understood from the above description, the visual field search can be performed by reading out the stored observation position specifying image, which facilitates the visual field search operation outside the visual field range. In addition, since the position is stored in addition to the image for specifying the observation position, the position for the re-observation can be easily set. Further, since the search for the visual field can be performed by reading the stored image, the damage of the sample due to the electron beam can be reduced.
[0014]
When the observation position specifying image is stored in the storage device 16, in addition to the image and the position signal of the image, the accelerating voltage when the image is obtained, the focusing condition of the lens, that is, the lens 5, 6, and 8 The excitation condition and the working distance (WD) may also be stored in the storage device 16. In this case, when the image for specifying the observation position is read, the acceleration voltage, the focusing condition of the lens and the working distance corresponding to the image can be read and set automatically by the control unit 24. Further, when the observation position designation image is read, the exciting current may be controlled by the control unit 24 so that the objective lens is focused.
[0015]
When storing the observation position specifying image in the storage device 16, the usage conditions of the detectors 14a and 14b may be stored together. In this case, when the observation position specifying image is read, the control unit 24 can also read out and automatically set the use conditions of the detectors 14a and 14b corresponding to the image.
[0016]
One or more positions on the observation position designation image displayed in the display surface area 23 and an image corresponding to the position and having a higher magnification than the displayed observation position designation image are stored in the storage device 16. May be. In this case, the stored position on the displayed observation position specifying image is displayed as a position display pointer on the displayed image, the display position is specified, and the stored position is stored. The high-magnification image can be read out and displayed on the display area 22.
[0017]
The observation position designating image to be stored in the storage device 16 may be a spliced image of images obtained by scanning a divided region of the sample with an electron beam. This is effective when observing an area wider than the scannable range.
[0018]
【The invention's effect】
According to the present invention, there is provided a scanning electron microscope suitable for facilitating a search for a visual field outside a visual field range.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a scanning electron microscope showing one embodiment according to the present invention.
FIG. 2 is a diagram showing a flowchart of sample observation as an example.
FIG. 3 is a diagram showing a coordinate position map on a sample stage of a stored image as an example.
FIG. 4 is a diagram showing an example of image display as an example.
[Explanation of symbols]
1: cathode, 2: electron beam, 3: extraction electrode, 4: acceleration electrode, 5, 6: focusing lens, 7a, 7b: deflector, 8: objective lens, 9: sample, 10: sample stage, 11: aperture , 12: lens control power supply, 13: secondary electron signal, 14, detector, 15: image display device, 16: storage device, 17: storage image control unit, 18: position designator, 19: sample stage drive unit, 21: position display pointer, 22, 23: image display area, 24: control unit, 26: scanning power supply, 27: magnification setting device, 28: position display pointer.

Claims (3)

Means for scanning the sample with an electron beam to generate an information signal characterizing the sample, means for detecting the generated information signal, and means for obtaining an observation image of the sample based on the detected information signal Means for storing the obtained observation image as an observation position designation image, means for reading out the stored observation position designation image, and means for reading the obtained observation image and the read observation position designation image. Means for displaying an image on each display surface, means for specifying an observation position on the displayed observation position specifying image, and position display of the specified observation position on the displayed observation position specifying image Means for moving the position display pointer in accordance with the movement of the designated observation position, and moving the designated observation position to a predetermined position on the display surface of the observation image. display Scanning electron microscope and means for controlling the scanning position of the electron beam of the sample so as to display the observation image corresponding to the designated viewing position to. 2. The scanning electron microscope according to claim 1, further comprising means for rotating the sample, wherein the position display pointer rotates in accordance with the rotation of the sample. 9. The scanning electron microscope according to claim 8, further comprising means for rotating the sample, wherein the designated position display image is rotated according to the rotation of the sample.

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