JPH06215720A - Electron microscope - Google Patents

Abstract

(57) [Abstract] [Purpose] Using the CPU to automate the movement of the sample stage, which was used to manually search for a sample in an electron microscope.
An object is to provide an electron microscope with high sample retrieval efficiency. [Structure] A sample table 4 on which a sample 5 is mounted is automatically moved in two directions of an X-axis and a Y-axis with a movement amount linked to a magnification of a transmission electron beam image. By displaying the driving conditions such as the moving range, moving speed, and acceleration / deceleration time of the sample table 4 on the condition display CRT 19 and setting the driving conditions by the operation unit 18, the sample 5 within the designated range can be searched. To configure. [Effect] By automating the conventional manual sample search, the sample search can be performed efficiently in a short time.
The operability of the electron microscope is dramatically improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron microscope, and more particularly, to an electron microscope suitable for searching a sample by automating driving means for moving a sample stage.

[0002]

2. Description of the Related Art Generally, in an electron microscope, the position of a desired visual field on a sample is searched in advance, and then the desired visual field is observed and analyzed again. The method of retrieval is to display the electron microscope image on the CRT monitor after converting it into an observation fluorescent screen or an electric signal, and then observe the electron microscope image and place the sample stage on the X-axis.
By manually moving in the direction of the axis or the Y-axis, the entire sample is thoroughly searched to find a desired field of view. Recent electron microscope C
Along with PU control, the automation of electron microscope operations has greatly advanced, and as disclosed in Japanese Patent Laid-Open No. 1-211844, there is a method for improving the efficiency of sample retrieval, but sample retrieval is still automated. It has not been.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to search for a sample, which was conventionally done manually in an electron microscope.
The purpose is to automate the movement of the sample table using the CPU and perform the search efficiently. Another object of the present invention is to provide an electron microscope having a high sample retrieval efficiency by designating a search region, designating a search speed, displaying a coordinate position of a desired visual field, storing, and displaying a previously searched region.

[0004]

In order to achieve the above object, in an electron microscope, a sample table on which a sample is mounted is mounted on an X-axis.
Driving means for moving in two directions of an axis and a Y-axis, a coordinate position of the sample, a driving condition of the sample stage, and a first display device for displaying the observation condition of the sample, and the driving condition And means for selecting or setting using the first display device, and means for searching an electron microscope image of the sample, that is, a second display device for displaying the electron microscope image, It is provided with a means for searching the sample thoroughly using a display device, that is, a means for automatically moving the sample stage by a movement amount linked to the magnification of the electron microscope image.

[0005]

An example using the CRT monitor as the first display device and the fluorescent plate as the second display device will be described. To move the sample stage, a moving mechanism in the X-axis direction and the Y-axis direction is used, and the CRT monitor is used. By specifying the driving conditions and instructing to execute the search, the sample stage automatically starts moving. The electron microscope image of the sample mounted on the sample stage is projected onto the fluorescent plate at any time during the movement, and the electron microscope image on the fluorescent plate may be observed until the desired visual field on the sample can be found. That is, there is no manual operation of moving the sample table. Further, since the moving amount of the sample table is automatically set in association with the magnification of the electron microscope, the electron microscope image of the sample is always projected on the fluorescent plate. Moreover, since the driving condition, that is, the search area and the search speed can be specified by using the CRT monitor,
It is possible to search various samples. Further, by displaying the moving path of the sample stage, double search can be avoided.
In addition, even if the magnification of the electron microscope is changed during the sample search, the movement amount is automatically corrected, and the sample search can be performed without stopping the search, dramatically improving the sample search efficiency. To do.

[0006]

1 is a block diagram of an electron microscope showing an embodiment of the present invention. The electron microscope converges the electron beam 2 emitted from the electron gun 1 by the irradiation lens system 3 and irradiates the sample 5 mounted on the sample table 4 with the electron beam 2. The electron beam 2 that has passed through the sample 5 is magnified by the imaging lens systems 6 a and 6 b and forms an electron microscope image on the fluorescent plate 7. Further, by moving the fluorescent plate 7 by the fluorescent plate moving mechanism 8, the electron microscope image is taken into the TV camera 9, the image is amplified by the camera controller 10, and displayed on the observation image display CRT 11. An electron microscope image photographing mechanism is attached to the lower portion of the fluorescent plate 7, but the illustration is omitted.

The microprocessor 14 includes a moving mechanism control circuit 15, a lens system control circuit 16 and a program memory 1.
7, the operation unit 18, and the condition display CRT 19 are connected, and the control of the electron microscope is performed via the microprocessor 14.

The sample 5 is moved by an X-axis direction moving mechanism 12 and a Y-axis direction moving mechanism 13 connected to the sample table 4. By synthesizing the two axes of the X-axis direction and the Y-axis direction, the entire range on the sample 5 can be observed. The movement mechanism control circuit 15 controls the X-axis direction movement mechanism 12 and the Y-axis direction movement mechanism 13 to control the movement speed of the sample table 4, the acceleration / deceleration time, the movement coordinate position, and the movement start and movement stop. The control condition setting on the sample table 4 is performed in the data input area displayed on the condition display CRT19. Data input area is 21b, 21c, 21
It corresponds to d and 21e. Also, the moving speed of the sample table 4,
The movement start and movement stop are equal to the retrieval speed, retrieval execution, and retrieval stop for the sample 5.

The operation unit 18 selects a data input area displayed on the condition display CRT 19 and inputs data.
The operation unit 18 is equipped with a numerical key switch for inputting data, a registration key switch for registering the input numerical value, and a selection key switch for selecting a data input area, and further, observation mode switching, magnification switching, acceleration voltage switching. Equipped with a key switch to do.

The lens system control circuit 16 controls the irradiation lens system 3 and the image forming lens systems 6a and 6b so that the observation mode or the magnification designated by the operation unit 18 is achieved.

Although all of these operations are performed via the microprocessor 14, the control of the moving mechanism control circuit 15 described above,
The control of the lens system control circuit 16, the control of the operation unit 18, and the display on the condition display CRT 19 are executed based on the electron microscope control program stored in the program memory 17 in advance and the sample automatic retrieval program.

The selection and data input of the data input area displayed on the condition display CRT 19 will be described in detail with reference to FIG. 20a is a specific display example of the condition display CRT 19. Reference numeral 20b denotes a sample position display area, which displays the position of the sample 5 by graphics. 21a is the observation condition of the sample,
That is, it is an area for displaying the observation mode, magnification, and acceleration voltage.

The data input area is a sample search speed input area 21b, a search area input area 21c, an execution instruction input area 21d for instructing search execution or search stop, and a memory number input area for storing the position coordinates of the sample. 21e, which are selected in order by pressing the selection key switch in the data input area on the operation unit 18.

In the search speed input area 21b, the search speed can be input from the operation unit 18, and the search speed can be 0.2 on the sample surface.
A speed corresponding to μm / s to 90.0 μm / s can be set. In the search area input area 21c, ± 20 μm in both the X-axis direction and the Y-axis direction centered on the current position from the operation unit 18
Search area corresponding to ± 60 μm, ie, 40 μm × 4
A search area of 0 μm to 120 μm × 120 μm can be set. It is also possible to specify the search of the entire sample surface.

In the execution instruction input area 21d, the operation unit 18
By pressing only the registration key switch, the search is executed. Further, although the search is temporarily stopped by pressing only the registration key switch again during execution of the search, the search is continued by pressing only the registration key switch again.

In the memory number input area 21e, memory numbers 0 to 19 can be input from the operation unit 18, and 20 kinds of position coordinates of the sample can be stored. In this embodiment, there are 20 types of storage of the position coordinates of the sample.
The upper limit is not limited.

Reference numeral 22a is a search route display of the sample, and the movement route after the search by graphics is displayed.

Reference numeral 22b denotes a sample present position display, which is also displayed in graphics.

Next, the movement instruction path of the sample stage and the movement control algorithm designated by the automatic sample retrieval program to the movement mechanism control circuit 15 will be described in detail with reference to FIGS. Two
3 is a search center position. The search center position 23 corresponds to the visual field coordinates at the time of instructing the search execution, and further corresponds to the sample table return coordinates at the end of the search. When the execution of the search is instructed, the coordinates of the search start point 24a are calculated by the following equation and designated to the moving mechanism control circuit 15. This corresponds to the process of A2 in the flowchart of FIG.

[0020]

[Equation 1]

Here, Px (0) is the X of the search start point 24a.
Coordinates, Px is the X coordinate of the search center position 23, Lx is the search area in the X-axis direction, and is set in the search area input area 21c. Similarly for the Y coordinate, Py (0) is the search start point 24.
a is the Y coordinate, Py is the Y coordinate of the search center position 23, Ly is the search area in the Y axis direction, and is set in the search area input area 21c.

The moving mechanism control circuit 15 determines the moving speed and the acceleration / deceleration time corresponding to the values specified in the search speed input area 21b.
Specify in. The acceleration / deceleration time is the time until the moving speed changes from zero to the steady state, or the time until the moving speed changes from the steady state to zero. When the moving speed is 10 μm / s on the sample surface, the acceleration / deceleration time is set to 100 ms. The moving speed and the acceleration / deceleration time are specified in the moving mechanism control circuit 15 only once at the time of initial movement, so that the conditions are maintained. This corresponds to the process of A3 in the flowchart of FIG.

By designating a movement start instruction to the movement mechanism control circuit 15, the movement to the designated coordinates is automatically performed. The movement mechanism control circuit 15 moves to the search start point 24a.
Drive instructions are simultaneously issued from the X-axis direction moving mechanism 12 and the Y-axis direction moving mechanism 13. (Corresponding to the processing of A4 in the flowchart of FIG. 4.) When the movement to the search start point 24a is completed, the coordinates of the next movement point P1 are continuously obtained by the following equations and designated to the movement mechanism control circuit 15. (Corresponding to the processing of A6 in the flowchart FIG. 4)

[0024]

[Equation 2]

Here, Px (1) is the X coordinate of P1, Py
(1) is the Y coordinate of P1. By designating the movement start instruction to the movement mechanism control circuit 15, the movement to the designated coordinates is automatically performed, and when the movement to P1 is completed, the coordinates of the next movement point P2 are continuously obtained by the following equation and the movement is performed. It is designated to the mechanism control circuit 15. When the next movement coordinate is designated, the X-axis direction movement mechanism 12 and the Y-axis direction movement mechanism 13 are in a stopped state, but since it is about 150 ms including the acceleration / deceleration time, it becomes a continuous movement image. (Corresponding to the processing of A6 in the flowchart FIG. 4)

[0026]

[Equation 3]

Here, Px (2) is the X coordinate of P2, Py
(2) is the Y coordinate of P2. By designating the movement start instruction to the movement mechanism control circuit 15, the movement to the designated coordinates is automatically performed, and when the movement to P2 is completed, the coordinates of the next movement point P3 are repeatedly obtained and the movement mechanism control is performed. Designate for circuit 15. Δy is the amount of movement in the Y-axis direction linked to the magnification of the transmitted electron beam image, and even if the magnification is changed, the Y of the observed image is changed.
The movement amount in the axial direction is set to be constant on the fluorescent plate. The amount of movement considers the overlap of the observed images so that a part of the observed image before the movement can be confirmed. Further, since the magnification of the transmitted electron beam image is based on the photographic mechanism, it is necessary to correct the magnification on the fluorescent screen. In the present embodiment, the amount of movement corresponding to 12 cm is set on the fluorescent plate in consideration of the overlap of the observed images, and the magnification correction value is set to 1.3. When the magnification of the transmitted electron beam image is M, Δy is calculated by the following equation.

[0028]

[Equation 4]

From the search start point 24a to the search end point 24b, the general formula for the X coordinate and the Y coordinate of the next moving point is P
If x (n) and Py (n) are used, it can be calculated by the following equation.

[0030]

[Equation 5]

However, n must be set so that Py (n) does not exceed the Ly range.

When the movement from the search start point 24a to the search end point 24b is completed, the sample table return coordinates, that is, the coordinates of the search center position 23 and a movement start instruction are designated in the movement mechanism control circuit 15, whereby The field of view coordinates are moved to and a series of sample retrieval is completed. (In the flowchart of FIG. 4, A7, A
Supports processing of 8. ) Further, by moving the fluorescent plate 7 by the fluorescent plate moving mechanism 8, it is possible to capture an electron microscope image in the TV camera 9 and perform a sample search on the observed image display CRT 11. However, it is necessary to monitor the state of the fluorescent screen 7 by a program and convert the movement amount Δy in the Y-axis direction so as to correspond to the observed image display CRT 11.

According to the present embodiment, both in the sample search on the fluorescent screen 7 and the sample search by the observation image display CRT 11, it is extremely suitable for automating the sample search and improving the efficiency.

[0034]

According to the present invention, the sample search, which was conventionally performed manually, is automated by using the CPU to move the sample stage, so that the sample search can be performed efficiently in a short time. The operability of the microscope is dramatically improved. Although the present invention has been described using the transmission electron microscope as an example, the present invention can be similarly applied to a scanning electron microscope.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electron microscope showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a specific example of the condition display CRT shown in FIG.

FIG. 3 is a configuration diagram showing a movement path of a sample table by a sample automatic search program.

FIG. 4 is a flowchart showing a movement control algorithm.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Electron beam, 3 ... Irradiation lens system, 4 ... Sample stand, 5 ... Sample, 6a ... Imaging lens system, 7 ... Fluorescent plate, 8 ...
Fluorescent screen moving mechanism, 9 ... TV camera, 10 ... Camera controller, 11 ... Observation image display CRT, 12 ... X-axis direction moving mechanism, 13 ... Y-axis direction moving mechanism, 14 ... Microprocessor, 15 ... Moving mechanism control circuit, 16 ... lens system control circuit, 17 ... program memory, 18 ... operation section, 19 ... condition display CRT, 20a ... condition display CRT, 20b ... sample position display area, 22a ... search path display, 22b ... sample current position display, 23 ... Search center position, 24a ... Search start point, 24b ... Search end point.

Claims (4)

[Claims] 1. In an electron microscope, driving means for moving a sample stage on which a sample is mounted in two directions of an X-axis and a Y-axis, coordinate positions of the sample, conditions for driving the sample stage, and the sample. A first display device for displaying the observation conditions of
It has means for selecting or setting the driving conditions using the first display device, and a second display device for displaying an electron microscope image, and using the second display device to set the sample stage. An electron microscope comprising: means for automatically moving the electron microscope with a moving amount that is interlocked with the magnification of the image. 2. The driving means according to claim 1, wherein the moving speed of the sample stage is controlled, and the time until the moving speed reaches a set value or the moving speed becomes zero. An electron microscope characterized by being able to control the acceleration / deceleration time. 3. The driving condition according to claim 1, wherein the moving speed of the sample stage, the moving range of the sample stage, the search area of the sample, and an instruction for executing the search of the sample are used. An electron microscope characterized by being able to display, select, and set using a display device. 4. The method according to claim 1, 2 or 3, wherein:
2. The electron microscope, wherein the display device and the second display device are the same.