JP2000133191A - Scanning electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the accurate recording of sample image and the accurate grasp of the recording magnification by displaying a recording area to be decided in response to the kind of a recording device for recording sample image so as to be overlapped with a sample image displayed in a display device. SOLUTION: Data of an image recording device can be output to two printers and while can be output to a photograph shooting device through a photographing signal converting device. An operator previously appoints a recording device for output (a photograph shooting device, or a printer 1 or a printer 2) with the operation of selecting buttons. Recording area different per each recording device can be previously set per each recording device. When the operator selects a desirable recording device, a corresponding recording area is displayed with a frame in an image display area. After the operator confirms that the desirable image area is included in the recording area, the operator operates a recording start button so as to start the recording.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam apparatus,
In particular, the present invention relates to a scanning electron microscope suitable for accurately specifying a field of view to be recorded from a display image displayed for observation or field search and a similar device.

[0002]

2. Description of the Related Art When recording a scanned image of a sample on a photograph, for example, a film size having an aspect ratio of 4: 3 is generally used in many cases. For this reason, a normal observation image is also displayed with the number of pixels (for example, 640 × 480 pixels) so that the aspect ratio becomes 4: 3, so that the field of view of the display image matches the field of view at the time of photograph recording. Further, in an apparatus having a fixed display mode and a fixed recording medium, a fixed frame indicating an area to be recorded on the recording medium is displayed on a display screen.

[0003]

However, recently, sample images are displayed in various display modes,
For example, displaying two or more images on the same CRT,
Scanning electron microscopes have been developed in which an operator can arbitrarily select various display modes such as displaying a sample image over the entire displayable area of the RT.

On the other hand, recording media for recording a sample image observed on a CRT include photographs and printers. Generally, the aspect ratio of a recorded image differs for each of these recording media. Therefore, even if an attempt is made to display a desired area of the display screen displayed on the CRT on the recording medium, the area actually recorded may not match the display area, and the recorded area may be contrary to the operator's expectation. There is a problem that the area of the sample image is narrow or wide.

Further, since the pixel size differs depending on the display device and the recording medium, the magnification of the sample image displayed together with the sample image generally becomes a value that is meaningful only for a specific display device, and the other recording values are not significant. There is a problem that it has no meaning for a medium or a display image.

Japanese Patent Application Laid-Open No. Hei 7-235276 discloses a frame for selecting an arbitrary region on a sample image of an electron microscope on a display device, and displays the frame based on designation of the size and position of the frame. Although there is a disclosure about a technique for performing film photographing, a sample image to be actually recorded is simply set to a desired area and is set independently of a recording area to be recorded on a recording medium. Has a problem that the area becomes narrow or widen contrary to the operator's expectation.

The present invention has been made to solve the above problems, and
Even in a scanning electron microscope to which various recording media are connected, it is possible to accurately record an area of a sample image intended by an operator or to accurately grasp a recording magnification thereof. It is intended for.

[0008]

In order to solve the above-mentioned problems, the present invention provides an electron source and a sample based on a secondary signal obtained by irradiating a primary electron beam emitted from the electron source. In a scanning electron microscope provided with a display device for displaying an image, a recording area determined according to a type of an external recording device for recording the sample image is displayed so as to overlap a sample image displayed on the display device. A scanning electron microscope characterized by comprising means is provided.

According to such a configuration, the operator can set the optical conditions of the scanning electron microscope while confirming the areas recorded by various recording devices.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic sectional view of one embodiment of the present invention. A voltage is applied between the cathode 1 and the first anode 2 by a high-voltage control power supply 20 controlled by a control CPU (microprocessor) 30, and a predetermined emission current is drawn from the cathode 1. A control C is provided between the cathode 1 and the second anode 3.
Since the accelerating voltage is applied by the high-voltage control power supply 20 controlled by the PU 30, the primary electron beam 4 emitted from the cathode 1
Is accelerated and proceeds to the subsequent lens system.

The primary electron beam 4 is supplied to a convergent lens control power source 21.
The unnecessary area of the primary electron beam is removed by the aperture plate 7 and converged as a minute spot on the sample 10 by the objective lens 6 controlled by the objective lens control power supply 22.

The primary electron beam 4 is two-dimensionally scanned on the sample by the scanning coils 8 arranged in two stages along the optical axis. At this time, the secondary signal 11 generated from the sample is detected by the secondary signal detection. Is detected by the detector 12 and is stored as an image signal in the image storage memory 25.
Is stored. The image information stored in the image storage memory 25 is displayed on the image display device 26 as needed.

An external recording device (not shown) is connected to the control CPU 30. These include, for example, photographic equipment,
There are printers and the like. In the control CPU 30, the aspect ratio of the recording area different for each of the external recording devices is registered in advance, and a display frame formed based on the aspect ratio can be displayed so as to be superimposed on the sample image on the image display device. It has become. By selecting an external output device to be used by an input device (not shown), display frames having different aspect ratios can be appropriately selected.

Further, it is preferable that the aspect ratio of the recording area can be newly registered in the control CPU 30 in case an external recording device not registered in the control CPU 30 is used. The scanning signal of the scanning coil 8 is controlled by the scanning coil control power supply 23 according to the observation magnification. The center position of the scanning area of the primary electron beam 4 is set to a predetermined position by the image shift coil 9 controlled by the image shift coil control power supply 24. The image signal is output to an image output device (CRT for photographing) 27 as needed. However, it may be output at any time.

In the apparatus according to the embodiment of the present invention, an image output device 27 is provided as a display device for photographing, and a photograph is taken based on a sample image displayed on the device. The image display device 26 displays the sample image for observation and the sample for imaging together, and performs image display device 2
6, the data registered in the image recording memory may be transferred to an external recording device and recorded.

The observation magnification is determined based on the size of the display area of the image display device and the size of the primary electron beam scanning area calculated based on the scanning signal of the scanning coil.

FIG. 2 shows a display image 100 displayed on the image display device, a display frame 101 of an image output area (photographing area) displayed over the display image, and a recorded image record 102. Is shown. In FIG. 2, the size (X1, Y1) of the display image 100 is determined by the size of the screen of the display CRT and the number of display pixels on the CRT. FIG. 3 shows a scanning region 103 of the primary electron beam on the sample during image display (during observation), and FIG. 4 shows a scanning region 104 of the primary electron beam on the sample during image output (recording or photographing). Is shown.

The processing from image display to image output will be described below according to the flow.

First, the operator searches for a predetermined field of view while viewing the display image (observation image), and determines the size of the observation area by the magnification switching means. Display image size X
Assuming that the display image magnification is Md and the display image magnification is Md, the size (x1, y1) of the beam scanning area on the sample is calculated as follows: x1 = X1 / Md y1 = Y1 / Md (1) Therefore, M
By changing d, the operator can enlarge and display a predetermined area on the observation sample on the display screen.

Next, the operator displays a frame indicating a recording area on the display screen, and sets the size and position of the display frame just including the area to be recorded on the display image by means such as a mouse pointer. it can.

The display frame has an internal size such that its size (X2, Y2) is changed while maintaining its aspect ratio at a predetermined value (a value determined by a recording medium or a value desired to be stored as electronic data). Processed and displayed. The size (X3, Y3) of the recording medium is set at the same time when the recording medium is set or specified. At this time, the magnification Mr of the recorded image is calculated as follows: Mr = X3 / x2 = Y3 / y3 (2), and the operator can display this value as needed. This display is performed by, for example, the image output device 27.
Above, it may be recorded together with the magnification of the sample image to be formed, or one of them may be displayed by switching.

Here, x2 and y2 are the primary electron beam scanning areas on the sample at the time of image recording. From the size of the frame 101 specified on the display image 100, x2 = (x1) × (X2 / X1 ) Y2 = (y1) × (Y2 / X1) (3) The control CPU 30 of the apparatus controls the scanning coil control power supply based on the calculated value and operates so that the primary electron beam scanning width on the sample becomes the value of the equation (3). Now,
The current of the scanning coil (both the X coil and the Y coil) is controlled by a step-like waveform as shown in FIG. One step of this scanning signal determines the distance between one pixel and the next pixel. That is, when an image is captured by Nx pixels in the X direction, the scanning signal amplitude corresponding to the image capturing area is Nx pixels.
It becomes a staircase wave of the divided current step ΔI.

Therefore, when capturing an image, the control CP
By U30, the change step width ΔI of the scanning coil control power supply is calculated and set so that the primary electron beam is scanned over the sample with a predetermined number of pixels. Further, at the time of image recording, the image storage memory captures an image signal at each step of changing the current of the scanning coil (each pixel) and stores it as image information.

On the other hand, the center of the display image 100 and the display frame 10
The distance (ΔX, ΔY) from the center of 1 is calculated from the display information, and from this value, the positional deviation amount (Δx, Δy) between the observed image (display image) and the recorded image converted on the sample is calculated. It is calculated by the following formula.

Δx = ΔX / Md Δy = ΔY / Md (4) The control CPU 30 controls the image shift coil control power source from the positional deviation obtained by the equation (4) during image recording, The primary electron beam is deflected by △ x and △ y on the sample, and then the primary electron beam scanning for image capture (recording) is started. As a result, since the scanning center on the sample is scanned at a position shifted by Δx and Δy from the time of observation, an image as indicated by 102 in FIG. 2 is recorded. Here, the beam movement amounts △ x and ら な い y must not exceed the maximum deflection amount of the image shift coil, and must be limited within a certain range. The control CPU 30 calculates this range in advance, and operates to prohibit frame movement beyond this range when the position of the recording frame is moved.

When the sample moving mechanism is driven by a motor,
In a device that can be controlled by the PU, this frame movement restriction is not required, and within the range in which the movement amounts △ x and △ y can be moved by image shift, the scanning center of the primary electron beam is moved by the image shift coil, and △ x , .DELTA.y are out of the control range of the image shift, the stage is controlled to operate so that the scanning position of the primary electron beam is at a predetermined position.

That is, the displayed image is merely an auxiliary means for determining the area and magnification of the recorded image. After the recorded image is specified, the recording is performed independently of the displayed image under the scanning conditions (scanning conditions) of the image. Area, the number of captured pixels, etc.) are set.
Further, the operator can change the magnification Md of the display image if necessary.
And the magnification Mr of the recorded image can be displayed simultaneously or by switching.

FIG. 6 shows a display frame 101 on a display image 100.
This is another embodiment in which the frame can be rotated. In this embodiment,
The rotation angle of the recording frame is calculated from the displayed image, and during image recording, the scanning direction of the primary electron beam on the sample is rotated in accordance with the angle. As a result, as shown in FIG. 6, the display frame 101 is recorded as a recording image 102 on the recording medium.

The calculation of the magnification and the calculation of the size and position of the scanning area of the primary electron beam by the apparatus according to the embodiment of the present invention are all controlled by the control C.
This is performed by the PU 30.

FIG. 7 is a diagram showing an embodiment in which a plurality of recording devices are connected to a scanning electron microscope. The sample image signal of the secondary signal detector of the main body passes through a signal processing device, and is stored in an image storage device
And sent to the photographing signal converter. The data in the image memory can be output to two printers, and at the same time, can be output to a photographic device via a photographic signal conversion device (circuit).

FIG. 8 shows a display example of the observation monitor of the image display device in the embodiment of FIG. (A) is an example in which two types of different signals (for example, images of a secondary electron signal and a reflected electron signal, or images with different magnifications) sent from the main body are simultaneously displayed on an observation monitor. In such a display form, one may be used for observing the sample image and the other may be used for selecting the recorded image.

By displaying in this manner, it is possible to search for a portion to be observed with a backscattered electron image and record a secondary electron image, for example. Since the secondary electrons and the reflected electrons have different information, if they are used properly depending on the composition of the sample, the visual field search of the sample can be smoothly performed. When displaying images with different magnifications, for example, if the high-magnification image is used for sample observation and the low-magnification image is used for recording image selection, the high-magnification image is used to select the recording area while confirming the detailed composition of the recording target area. It can be performed.

Further, a means for selecting a signal for recording an image in advance is provided so that the operator can select the signal. A frame indicating a recording area is displayed on the monitor image displaying the selected signal image. (B) is an example in which one signal image is displayed. In this case as well, a frame indicating the recording area is displayed so as to overlap the display area of the sample image. (C) shows a frame indicating the recording area superimposed on the display area of one sample image, but the observation monitor displays the image area in addition to the display of this image area.
A button for selecting a recording device is also displayed.

The operator designates a recording device (photographing device or printer 1 or printer 2) to be output in advance by operating this selection button (for example, by means such as a mouse pointer).

Each of these printing apparatuses has a different printing area (ratio of the height and width of an image at the time of printing), and this area can be set in advance for each printing apparatus. Therefore, when the operator selects a desired recording apparatus, a corresponding recording area is displayed as a frame in the image display area. The operator can easily determine whether or not a desired image area is recorded by looking at this frame. After confirming that the desired image area is included in the recording area, the operator operates the recording start button to start recording.

As described above, the recording device selection switch and the recording frame of the recording device selected by the selection switch are displayed on the observation monitor visually observed by the operator.
The operator can select an appropriate recording device according to the sample to be acquired.

In the examples of FIGS. 8A to 8C, the size and position of the recording area frame displayed in the image area can be changed by the operator while maintaining the aspect ratio corresponding to the recording apparatus. . For example, when the corner of the frame is dragged with the mouse pointer, the size of the recording area frame changes while maintaining the aspect ratio, and when the mouse pointer is dragged inside the frame, the position of the frame with respect to the sample image can be changed. No matter what size you set, the aspect ratio of the frame does not change,
The operator can selectively record a desired portion of the sample image formed on the observation monitor.

Further, according to the apparatus of the present invention, the position selected on the observation monitor is set as the electron beam scanning range,
Since a sample image is obtained, a sample image with high resolution can be recorded.

[0040]

According to the present invention, the area of the output image can be clearly specified for an arbitrary output medium, and the magnification can be accurately displayed for the required image. An accurate output field of view can be efficiently selected, and the usability of the scanning electron microscope is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an output area and an output image designated on a display image.

FIG. 3 is a diagram showing a primary electron beam scanning area on a sample corresponding to a display image area.

FIG. 4 is a diagram showing a primary electron beam scanning area on a sample corresponding to an output image area.

FIG. 5 is a diagram showing a scanning signal current flowing through a scanning coil.

FIG. 6 is a diagram showing an image output area and an output image set in a rotated state on a display image.

FIG. 7 is a diagram showing an embodiment in which a plurality of recording devices are connected to a scanning electron microscope.

FIG. 8 is a view showing a display example of an observation monitor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cathode, 2 ... First anode, 3 ... Second anode, 4 ... Primary electron beam, 5 ... Convergent lens, 6 ... Objective lens, 7 ... Aperture plate, 8
... Scan coil, 9 Image shift coil, 10 Sample, 11 Secondary signal, 12 Secondary signal detector, 20 High voltage control power supply, 21 Convergent lens control power supply, 22 Objective lens control power supply, 23 Scan coil control power supply, 24 ... Image shift coil control power supply, 25 ... Image storage memory, 2
6 image display device, 27 image output device, 30 control CP
U, 100: size of display image, 101: area of output image with respect to display image, 102: recorded image, 103
... Primary electron beam scanning area on the sample corresponding to the display image area, 104. Primary electron beam scanning area on the sample corresponding to the image output area.

Claims (12)

[Claims] 1. A scanning electron microscope comprising an electron source and a display device for displaying a sample image based on a secondary signal obtained by irradiating a primary electron beam emitted from the electron source.
A scanning electron microscope comprising means for displaying a recording area determined in accordance with the type of an external recording device for recording the sample image on a sample image displayed on the display device. 2. A scanning electron microscope according to claim 1, further comprising means for calculating a magnification of a sample image recorded by said external recording device. 3. The scanning electronic device according to claim 2, wherein the magnification of the sample image recorded by the external recording device is calculated based on the scanning area of the primary electron beam and the size of the recording area. microscope. 4. The apparatus according to claim 1, further comprising means for switching or simultaneously displaying a magnification of a sample image formed on said display device and a magnification of a sample image recorded by said external recording device. A scanning electron microscope characterized by the above-mentioned. 5. A scanning electron microscope according to claim 1, further comprising means for inputting a size of an image output to said display device. 6. The scanning electron microscope according to claim 1, further comprising means for displaying the recording area on the display device as a frame superimposed on the sample image. 7. The display according to claim 6, further comprising: means for changing the size of the frame, wherein the magnification display displayed on the display device is changed in conjunction with the change in the size of the frame by the means. A scanning electron microscope comprising a magnification control means. 8. A scanning electron microscope according to claim 6, further comprising means for moving said frame on said display device. 9. A method according to claim 1, further comprising a selection means for selecting a method of changing the magnification of the display image at a predetermined magnification step and a method of changing the magnification of the output image at a predetermined magnification step. And a scanning electron microscope which controls a primary electron beam scanning width on the sample so as to achieve a change in magnification specified by the selecting means. 10. A primary electron beam emitted from an electron source is scanned on a sample, a secondary signal generated from the sample is detected to obtain a scanned image, and the scanned image is displayed by a plurality of different numbers of pixels. Image display means, pixel selection means for selecting the image display pixels, magnification display means for displaying the magnification of the scanned image,
What is claimed is: 1. A scanning electron microscope comprising image output means for outputting said scanned image to a recording medium, wherein a designated area on a display screen is output to a designated recording medium with a preset number of pixels. Scanning electron microscope. 11. An image display device according to claim 10, further comprising means for displaying the image magnification on a display screen and the image magnification when an area designated on the display screen is output to said recording medium, separately or by switching. A scanning electron microscope characterized by the above-mentioned. 12. A sample is scanned with a primary electron beam, a sample image is formed based on a secondary signal generated from the scanning area, and a sample image to be recorded by an external recording device is formed based on the formed sample image. A method for recording a sample image by a scanning electron microscope to be determined, wherein a recording frame determined according to the type of the external recording device is superimposed and displayed on the sample image, and the frame is matched to the recording frame. Change the scanning area of the primary electron beam,
A sample image recording method using a scanning electron microscope, wherein the sample image is recorded based on a secondary signal generated from the changed scan area.