JPH06124677A - Sample image movement control device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a charged particle beam device such as a scanning electron microscope, the inconvenience of adjusting the observation angle is solved and the operation efficiency is improved. A rectangular cursor is drawn so as to be superimposed on a sample image on a display device 12, and a central control circuit 10 moves a stage 8 or a deflector according to information from a cursor movement indicator 14 having cursor rotation instruction means. The current values of 3 and 4 are controlled to change the position of the charged particle beam on the sample so that the portion surrounded by the rectangular pattern cursor is displayed on the full screen of the display 12 at an angle aligned with the screen. The sample image was moved, the magnification was changed, and the observation angle was changed at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample image movement control apparatus for a charged particle beam apparatus such as a scanning electron microscope.

[0002]

2. Description of the Related Art Conventionally, when observing a part of a large sample at a high magnification using an apparatus such as a scanning electron microscope, first, a wide area on the sample surface is displayed at a low magnification and the part to be observed is searched for. After that, the stage is moved by operating the stage movement indicator such as a joystick or a trackball so that the portion to be observed is located substantially in the center of the CRT display. Next, the magnification of the electron microscope is increased, and when the portion to be observed on the screen with the changed magnification is not near the center of the display screen, the stage is moved so that the portion comes to the center again.
After that, move the stage while raising the observation magnification little by little, and adjust so that the portion you want to observe at the required observation magnification comes to the center of the display, and then the observation image in the electron optical system at an angle convenient for observation. Was controlled in two dimensions by controlling the deflector.

When moving a sample image displayed at a high magnification, it is sometimes necessary to use not only the movement of the stage but also the operation of electrically controlling the deflector in the electron optical system to move the visual field. It was Therefore, by moving the cursor to the part you want to observe while displaying a wide area sample image at low magnification, enclosing that part in a rectangular frame and pressing the execution command switch etc., you can select the part you want to observe on the sample. It is designed so that it can be displayed at the desired magnification and in the center of the screen, and the procedure for moving the sample image to be observed is greatly simplified to improve operability and shorten the observation time. One has been proposed in JP-A-63-285854.

[0004]

[Problem to be Solved by the Invention] Changing the observation angle, however, in the configuration proposed hitherto, the desired portion of the sample image can be easily displayed at the desired magnification in the center of the screen. When it is difficult to see because the part to be rotated is rotated, it is necessary to adjust the dial or the like to adjust the current flowing through the deflector to change the observation angle. An object of the present invention is to solve the inconvenience of the conventional adjustment of the observation angle and to improve the operation efficiency.

[0005]

In order to achieve the above object, according to the present invention, a central control circuit causes a rectangular cursor to be drawn by superimposing it on a sample image on a display, and a cursor movement instruction having a cursor rotation command means. Based on the information from the device, the central control circuit calculates the stage movement, that is, the direction and size of the mechanical visual field movement, the electrical visual field movement, the magnification to be changed, and the screen angle to be changed. The sample image was moved, the magnification was changed, and the observation angle was changed at the same time so that the enclosed portion fills the screen of the display at an angle aligned with the screen.

The scanning position on the sample by the charged particle beam may be obtained by relatively moving the scanning region of the charged particle beam and the sample. The stage on which the sample is placed is moved to move the sample with respect to the scanning region. The mechanical visual field movement may be performed only, the electric visual field movement that moves the scanning region with respect to the sample by the current control of the deflector may be performed, or the mechanical visual field movement and the electrical visual field movement may be used together. .

Further, at the timing of displaying the portion surrounded by the rectangular pattern on the full screen of the display at an angle aligned with the screen, an execution command switch is provided, and the central control circuit receives the execution command signal from this switch. It is preferable to do so.

[0008]

Therefore, when observing a part of a large sample at a high magnification using a charged particle beam device such as a scanning electron microscope,
The operator first displays a sample image of a wide area at a low magnification on the display, confirms the part to be observed, moves the cursor with the cursor movement indicator, encloses that part in a rectangular frame, and adjusts to the angle to be observed. By simply rotating the rectangle, you can display the portion of the sample you want to observe at the desired magnification and at the center of the screen at the angle you want to observe.

[0009]

1 is a block diagram of an embodiment in which the present invention is applied to a scanning electron microscope. In FIG. 1, 1 is an electron gun,
2 is an aperture, 3 is a horizontal scanning deflector, 4 is a vertical scanning deflector, 5 is an objective lens, 6 is a detector, 7 is an observation sample, 8 is a stage, 9 is an electron optical system control circuit, 10 is a central control circuit, 11 is an image signal amplification circuit, 12 is a CRT display, 13 is a stage control circuit, 14 is a cursor movement indicator having a cursor rotation command knob 14a, and 15 is A
The / D converter, 16 is a frame memory.

The electron beam emitted from the electron gun 1 and passing through the aperture 2 is deflected in the horizontal and vertical directions by the deflectors 3 and 4, and then converged by the objective lens 5 to hit the observation sample 7. The electronic optical system control circuit 9 controls each functional block 1, 3, 4, 5 in the drawing so that a desired position can be observed at a magnification and an angle designated by the operator. Secondary electrons or backscattered electrons generated when the electron beam hits the sample 7 enters the detector 6, is converted into an electric signal and is amplified by the image signal amplifying circuit 11, and is then converted into a digital signal by the A / D converter 15, and is then stored in the frame memory. It is stored in 16 as digital image information. The digital image information in the frame memory 16 is sent to the CRT display 12. The CRT of the CRT display 12 is swept in the horizontal and vertical directions with a sawtooth wave signal in accordance with a command from the central control circuit 10, and CRT is read by the pixel information sequentially read from the frame memory 16.
CRT by applying brightness modulation to the corresponding pixel of RT
Form a sample image on top.

Further, the central control circuit 10 moves the cursor on the CRT display 12 so that a graphic cursor formed in a rectangular pattern is displayed at a position designated by the cursor movement indicator 14 so as to be superimposed on the sample image. The position information is added to the output of the frame memory 16 in synchronization with the reading of the image information from the frame memory 16. Central control circuit 1
0 inputs the cursor size information from the cursor movement indicator 14, the cursor movement information, and the cursor rotation information obtained corresponding to the rotation amount of the cursor rotation command knob 14a. The position and orientation are calculated, and a signal for displaying a cursor on the CRT according to a command from the cursor movement indicator 14 is output in synchronization with the reading of the image information from the frame memory 16. The operator operates the cursor movement indicator 14 to change the size of the cursor and to move and rotate the cursor to perform CR.
A portion of the sample image on T to be observed is surrounded by a rectangular pattern. FIG. 2 shows this state, and the solid line 140 indicates the graphic cursor formed in the rectangular pattern.

Based on the information from these cursor movement indicators 14, the central control circuit 10 coordinates the center of the cursor with respect to the center coordinates of the screen of the CRT (corresponding to the coordinates on the surface of the sample 7). Then, the coordinates of the center of the cursor are converted into the coordinates on the surface of the sample 7, and the coordinates 140a of the vertex of the rectangular pattern 140 shown in FIG. 2 and the inclination angle θ of the cursor with respect to the horizontal line are calculated. The central control circuit 10 obtains the moving direction and the moving amount of the stage 8 based on the converted value, and also determines the magnification to be changed according to the distance obtained from the center coordinates of the cursor 140 and the vertex coordinates 140a. The scan angle to be changed is calculated from the tilt angle θ of the cursor 140.

The central control circuit 10 sends a signal to the electron optical system control circuit 9 and the stage control circuit 13 by operating an instruction execution switch attached to the cursor movement indicator 14, so that the center of the cursor 140 is at the center of the CRT. The stage 8 is moved to the first position and the currents flowing through the deflectors 3 and 4 are controlled to change the magnification (change the size of the scanning region) and the scan angle (change the scanning direction) at the same time. By scanning the electron beam on the surface of the sample 8 at an angle of −θ with respect to the horizontal line, the sample image obtained by rotating the cursor 140 by θ can be displayed on the CRT. As a result, the cursor 1 shown in FIG. 2 is displayed on the CRT of the CRT display 12 as shown in FIG.
The sample image in the area indicated by 40 is enlarged and displayed with the angle adjusted.

When the field of view of the sample image is moved, if the amount of movement is small, the vertical direction of the electron optical system,
The horizontal scanning deflectors 3 and 4 can be controlled to move the electron beam scanning area on the surface of the sample 7 to move the visual field. In the above description, the case where the visual field of the sample image is moved by moving the stage has been described. However, since the response is quicker when the visual fields are moved by controlling the deflectors 3 and 4, the central control is performed also in this embodiment. After calculating the amount of movement on the surface of the sample 7, the circuit 10 can determine whether to drive the stage 8 or control the electron beam deflectors 3 and 4 according to the amount of movement.

Of course, the visual field movement by the stage 8 and the visual field movement by the electron beam deflectors 3 and 4 are not alternatives,
You may use together. Further, in this embodiment, the digital signal output from the A / D converter is stored in the frame memory as image information, and the digital image information in the frame memory is sent to the CRT display. The digital signal output from the A / D converter may be directly sent to the CRT display.

[0016]

As described above, according to the present invention, the operability can be improved and the observation time can be shortened by greatly simplifying the procedure for moving the visual field of the sample image to be observed.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment in which the present invention is applied to a scanning electron microscope.

FIG. 2 is a diagram showing a CRT screen of a CRT display according to an embodiment of the present invention.

FIG. 3 is a CRT after pressing an instruction execution switch after enclosing a portion to be observed with a rectangular pattern as shown in FIG.
Display screen. The area surrounded by the rectangular pattern in FIG. 2 is C
It is a figure which shows a mode that the CRT screen of an RT display is expanded and displayed.

[Explanation of symbols]

 1 Electron Gun 2 Aperture 3 Horizontal Scan Deflector 4 Vertical Scan Deflector 5 Objective Lens 6 Detector 7 Observation Sample 8 Stage 9 Electron Optical System Control Circuit 10 Central Control Circuit 11 Image Signal Amplification Circuit 12 CRT Display 13 Stage Control Circuit 14 Cursor Movement indicator 14a Cursor rotation command knob 15 A / D converter 16 Frame memory

Claims (1)

[Claims] 1. An electron optical system that two-dimensionally scans a desired area on a sample surface with a charged particle beam such as an electron beam, and the sample is placed on the axis of the electron optical system. A sample moving unit that moves mechanically in a vertical plane, a display unit that displays a sample image on a display based on a signal obtained from the sample by scanning with the charged particle beam, the electron optical system and the sample moving unit. A central control circuit for controlling the means and displaying a rectangular cursor by superimposing it on the sample image, and a cursor indicator for instructing the central control circuit of the position and size of the cursor on the display, In the movement control device for the sample image provided with, the cursor indicator has a cursor rotation command means for displaying the cursor at an arbitrary rotation angle, the central control circuit for displaying a rectangular cursor, Curso Information on the rotation angle of the cursor from the rotation instruction means, the sample image in the area designated by the cursor is enlarged and displayed on the screen of the display device at the same angle as the screen. A device for controlling the movement of a sample image, which is characterized by controlling