JPH0223972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant movement zoom device used in a scanning electron microscope or the like.

In devices such as scanning electron microscopes and ion microanalyzers, a finely focused charged particle beam irradiates the sample surface and at the same time scans a certain area to detect various signals obtained from the sample. . The detection signal is synchronized with the scanning.
It is used as a brightness modulation signal for an image display device such as a CRT, and a brightness modulated scanned image is displayed on the image display device. The magnification of the scanned image is determined by the ratio of the scanning width of the electron beam that irradiates the sample to the corresponding length of the display screen.

In normal sample observation, a low magnification image is first observed, and the sample moving device is manually operated so that the desired field of view is approximately in the center of the screen. In this state, if you increase the magnification, the desired field of view will be enlarged and displayed, but if you want to observe a specific part of this expanded field of view in more detail, you can repeat the same operation using the sample moving device. is repeated.
Therefore, in normal sample observation, it is necessary to perform the above-mentioned operation several times before finding the desired field of view. Moreover, the sample moving device cannot move the sample in any direction unless two independent knobs are operated to move the sample in two mutually orthogonal directions in a plane perpendicular to the electron beam, that is, the X direction and the Y direction. Moreover, the moving speed of the sample was either too fast or too slow compared to the magnification, making it impossible to move it in the desired direction or stop it at a desired position. Therefore, the operator requires a great deal of time and effort to bring the desired visual field to the center of the screen.

The present invention has been made in view of these points, and includes a moving means for moving the center of the scanning area of the electron beam on the sample in the X direction and the Y direction relative to the sample, and a means for moving the center of the scanning area of the electron beam on the sample in the X direction and the Y direction, and a magnification. means for supplying a movement signal of a predetermined amount; a scanning width variable device for determining the amplitude of the X and Y scanning signals supplied to the scanning coil in the lens barrel; and dividing means for dividing the CRT screen by drawing lines or the like. , an indicating means for indicating an arbitrary divided area divided by the dividing means, and an image portion displayed within the area specified by the indicating means is automatically moved to the center of the screen, and The control means for controlling the moving means and the scanning width variable device so that the part is enlarged and displayed allows for a scanning electron microscope that integrates sample movement and magnification zoom to greatly improve operability. This realizes a moving zoom device.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an electrical configuration diagram showing an embodiment of the present invention. In the figure, 1 is the lens barrel, 2 is the sample
A scanning coil 3 that scans with a beam dimensionally is a driving unit having a sample stage 3a on the upper surface of which a sample (not shown) is placed. Reference numeral 4 denotes a scanning width variable device that drives the scanning coil 2, and the magnification of the displayed image can also be changed by the scanning width variable device 4. For example, reduce the scan width by 1/2
If you do this, the magnification will be doubled. 5 is scanning coil 2
Scanning power supplies 6 and 7 that supply scanning voltage to
Step motors 8 and 9 that move in the Y direction are pulse generators that send driving pulses to these step motors 6 and 7.

10 is a scanning width variable device 4 and pulse generators 8 and 9
This is a control unit that controls the As the control unit 10, for example, a microcomputer is used.
Reference numeral 11 denotes a control switch having push buttons corresponding to the number of divisions of the CRT screen divided by lines as shown in FIG. As shown in Fig. 2, the CRT screen of this embodiment is divided into nine sections from section A to section I, and the length occupied by each section is calculated by setting the total length of the screen to be 1 in both the vertical and horizontal directions. The proportions (same in both vertical and horizontal directions) are shown in the figure. this
The CRT screen is divided into sections from A to I,
The push buttons A to I of the control switch 11 correspond to each other. In addition, to divide the CRT screen, use the lined transparent plate to separate the CRT screen.
The structure may be attached to the CRT screen, or it may be drawn as a bright line or line on the CRT screen.

The operation of the apparatus of the present invention configured as described above will be explained next.

Assume that the target sample is now located at position A in FIG. 2 on the screen. The operator then presses button A on the control switch. As a result, a signal specifying the moving direction of the sample stage 3a is output from the control switch 11 to the control section 10. A signal specifying the number of pulses according to the magnification is given from the control section 10, and the pulse generators 8 and 9 receive these two signals and output the corresponding number of pulses. Step motors 6, 7 receive output pulses from pulse generators 8, 9 and move sample stage 3a in the direction shown by arrow A in FIG. The moving distance is the distance Sx (2/8) that moves the image on the screen by 2/8 in the X direction and 2/8 in the Y direction.
8), Sy (2/8). After the move is complete,
The control section 10 sends a control signal to the variable scanning width device 4 to enlarge the displayed image on the CRT screen twice.
As a result, the sample image moved in the direction of arrow A is enlarged twice at that position and displayed on the CRT screen.

In the above-mentioned operations, the moving operation was explained when the sample was located in section A in FIG. 2, but the operation is exactly the same when the sample is located in any of sections B to I. For example, when in the position of section G, pushbutton G of control switch 11 may be pressed. As a result, the sample moves in the direction of arrow G in FIG. 3 and is then enlarged twice. The same applies to cases where the sample is at other positions, and the sample moves in each direction as shown in FIG. However, button E
It does not move when you press . When it is not possible to obtain a scanned image at a predetermined position and a predetermined magnification even with such a first movement and enlargement operation,
By repeating the same operation again, it is possible to finally obtain a scanned image at the desired magnification at the center of the screen. In addition, the first moving enlarged scan
The scanned image displayed on the screen is magnified twice, so when performing the second movement and enlargement operation, the pulses necessary to move it the same distance as the first time on the CRT screen are generated. The number of output pulses from devices 8 and 9 will be 1/2 of the previous number. in this way,
Pulse generator 8,9 each time it is doubled.
This is because unless the number of output pulses is reduced by half, the image of the area of interest will extend beyond the CRT screen. This control is performed by the control section 10.
Figure 4 shows how, when an image P of a part of interest is displayed on the screen, how this part changes and is enlarged and displayed in the center as the above operation is performed. This example shows two examples. The alphanumeric mark on the left side of the CRT screen indicates the type of button pressed. As is clear from FIG. 4, according to the device of the present invention, the operator can
You can move and enlarge the sample by simply pressing buttons while looking at the CRT screen. Therefore, operability is greatly improved.

Next, in order to explain the effects specific to the above-mentioned embodiment, we will explain how much narrower an arbitrary part within an area of 3/4 of one side of the center of the screen is from the center of the next screen by one enlargement operation. Whether it is possible to drive into the area and expand it will be explained with reference to FIG. Figure 5 (),
() and () are shown by taking three cases as an example, and the alphabet in the figure indicates the type of button that was pressed. Further, S indicates the screen, Z indicates the desired field of view (that is, the portion of the sample image of interest), and K indicates the size when Z is enlarged. Taking the case () as an example, in order to bring the desired field of view Z to the center of the screen, push button A of the control switch 11 is pressed. Then, the field of view Z moves in the direction of arrow A in FIG. 3 and moves to the center of the screen as shown at ()-2. Thereafter, the image displayed on the CRT screen is enlarged twice as much as shown in ()-3, occupying 1/4 of the entire screen. Note that the example shown in () is the same as (). However, in the case of the example shown in (), the desired field of view Z is already at the center of the screen S, so when pushbutton E is pressed, () -
The screen will be enlarged twice as shown in Figure 3. Although the case where the desired field of view Z is located in sections A, B, and E (see Figure 2) has been explained, if the desired field of view Z is located in sections C, D, F,
The same is true for the positions G, H, and I, and it can be placed within the center 1/4 screen with one movement and enlargement operation.

As shown in Figure 6, the entire length of the initially imaged sample surface is expanded to 1/4 of the center by moving and enlarging operations t and n times.
If the length of the portion that can be included on the screen is h, then when n=1, the ratio of h/t is 50+25=75%. The remaining 25% (W in the figure) cannot fit into the center 1/4 screen when magnified twice. Repeat the same operation again 2 ²
= When multiplied by 4, the ratio of h/t is 50 + 25 + 12.5 =
87.5%. Then double it again to make the total 2 ³ = 8 times, the h/t ratio is 50 + 25 + 12.5 + 6.25 =
It becomes 93.75%. That is, if the initial screen is multiplied by 8 (n=3), 93.75% of the entire area can be placed within the 1/4 screen at the center of the screen.

As is clear from the above explanation, in this embodiment, the part of the sample image of interest is always displayed in the center of the screen, compared to the case where the screen is divided into 9 equal parts and moved by 1/3 for enlargement. Enables efficient magnified observation.

The case where the image is enlarged twice by one movement and enlargement operation has been described above, but it goes without saying that the magnification does not need to be limited to twice. If the magnification is generally set to a, the proportions of each area shown in Figure 2 should be as shown in Figure 7 in order to efficiently magnify and observe the area of interest while always displaying it in the center of the screen. . (a-1)/2a in the figure indicates the cursor width. The direction of movement of the sample when the push button is pressed is as shown in FIG. Note that any part of the area in the center of the screen whose side is (3a-3)/2a can be expanded once to fit into the narrow area (limited range) in the center of the next screen. The width of this limited range is (a-1)/2 as shown in Figure 9,
The relationship between the magnification a and the proportion of the limited range on the screen is shown in FIG. In the figure, f ₁ is a curve showing the limited range, f ₂ is a curve showing the cursor width, and this curve is also a curve showing the amount of sample movement on the CRT.

It should be noted that the above-described embodiment is only one embodiment of the present invention, and many other embodiments may be adopted. For example, if you divide the screen into 9 equal parts and move the image by 1/3 with each enlargement, the center of the divided part specified by the switch will be at the center of the screen and the image will be enlarged. , it becomes an easy-to-understand enlarging device that allows you to easily associate the pressed button with each divided portion.

Furthermore, in the above-described embodiment, the sample stage was moved to move the center of the electron beam scanning area on the sample, but the DC bias signal added to the output signal of the variable scan width device and supplied to the scanning coil If the output value from the source is controlled by the control unit 10 according to the pressed button and the magnification at that time, the center of the scanning area can be moved electromagnetically, which is particularly suitable for high-magnification observation. It becomes a mode.

As described above in detail, according to the present invention, it is possible to realize a constant movement zoom device for a scanning electron microscope, which integrates sample movement and magnification zoom, thereby significantly improving operability.

[Brief explanation of drawings]

FIG. 1 is an electrical connection diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a divided state of a CRT screen,
Fig. 3 is an explanatory diagram showing the moving direction of the sample, Fig. 4 is an explanatory diagram showing an example of the operation of moving and enlarging the specimen on the CRT screen, Fig. 5 is an explanatory diagram showing the movement of the field of view on the CRT screen, and Fig. 6 is an explanatory diagram showing the movement of the specimen on the CRT screen. The figure is an explanatory diagram showing the proportion of the sample surface that falls within 1/4 screen, Fig. 7 is an explanatory diagram showing the divided state of the CRT screen when the magnification is a, and Fig. 8 is an explanatory diagram showing the moving direction of the sample at this time. FIG. 9 is an explanatory diagram showing the limited range of the CRT screen, and FIG. 10 is an explanatory diagram showing the relationship between the magnification a and the ratio of the limited range to the screen. DESCRIPTION OF SYMBOLS 1... Lens barrel, 2... Scanning coil, 3... Drive unit, 3a... Sample stage, 4... Scanning width variable device, 5...
...Scanning power supply, 6,7...Step motor,8,
9...Pulse generator, 10...Control unit, 11...
control switch.

Claims (1)

[Claims] 1. A moving means for moving the center of the scanning area of the electron beam on the sample in the X and Y directions relative to the sample, a means for supplying a moving signal of an amount determined by the magnification to the means, and a lens barrel. a scanning width variable device that determines the amplitude of the X and Y scanning signals supplied to the scanning coil in the interior, a dividing means for dividing the CRT screen by drawing lines, etc., and an arbitrary divided area divided by the dividing means. an instruction means for instructing, and a scanning width and an instruction means for automatically moving the image portion displayed within the area specified by the instruction means to the center of the screen and enlarging the area. A constant movement zoom device comprising a control means for controlling a variable device.