JPH03167460A - X-ray microanalyzer - Google Patents

Abstract

PURPOSE:To improve the reproducibility of a position so that a sample is correctly located at a preset analyzing point by controlling a finely moving means of the sample so that the output of comparison in an image comparing part becomes the minimum value. CONSTITUTION:When a sample (s) is analyzed, an analyzing mode is set with a setting means 26. A stage driving means 4 is controlled based on a moving amount stored in a table memory 32 with a first control means 34a, and a sample stage (X, Y and Z) 2 is moved. After the movement of the sample stage 2, image data are picked up again. The image data and image data which are obtained in reference to the table memory 32 are collated, and the degree of agreement is judged. A finely sample moving means 16 is controlled with a second control means 34b so that the output of the comparison in the comparing part 36 becomes the minimum value, and the sample (s) is minutely moved. When the output of the comparison from the comparing part 36 becomes the minimum value, it is judged that the position of the present analyzing point perfectly agrees with the position of the analyzing point which is set beforehand. Thereafter, analysis for detecting the characteristic X rays is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an X-ray microanalyzer, and particularly to a technique for accurately moving a sample to a pre-registered analysis point in automatic analysis.

Conventionally, when performing automatic analysis with an X-ray microanalyzer, as shown in Figure 3, a pulse motor is driven while observing an optical microscope or secondary electron (SEM) image to measure the sample S.
The sample stage is moved from the reference position O so that the desired analysis point A coincides with the electron beam irradiation position, and this movement amount (
XO, yo) data is registered in advance in the computer. During actual analysis, the sample stage is moved based on the data of the amount of movement (XO, yo) registered in the computer.

<Problem to be solved by the invention> However, because the sample stage is subject to factors such as mechanical play and temperature changes, it is difficult to move the sample stage so that the sample is located at the previously set analysis point. Even if you intend to do so, the position may actually be misaligned. Particularly when it is desired to perform analysis at high magnification, the analysis point A becomes minute, so occurrence of such a positional shift is undesirable.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve positional reproducibility so that a sample is accurately positioned at a preset analysis point.

Means for Solving the Problems Therefore, the present invention provides a sample stage for mounting a sample that is movable in three axes directions, and a stage drive means that drives the sample stage individually in each axis direction. , an electron gun that irradiates the sample with an electron beam, a scanning means that two-dimensionally scans the electron beam from the electron gun, and a secondary electron (
An X-ray microanalyzer that includes a detector that detects reflected electrons) and an image memory that stores the detection signal detected by the detector as image data has the following configuration.

That is, the X-ray microanalyzer of the present invention has a sample fine movement means having a fine movement element for finely moving the sample, a position registration mode for registering an analysis point, and an analysis mode for moving the sample to the registered analysis point during analysis. a setting means for setting, a table memory for storing in correspondence the amount of movement of the sample stage from the reference position in the position registration mode and image data obtained under this amount of movement; a first control means for controlling the stage driving means based on stored movement amount data; image data obtained at the sample position moved by the first control means; and image data obtained by referring to the table memory. The apparatus includes an image comparison section that compares and collates image data to determine the degree of coincidence, and a second control section that controls the sample fine movement means so that the comparison output of the image comparison section is minimized.

Function> To perform automatic analysis, set the position registration mode using the setting means in advance, and drive the stage drive means to move the sample stage so that the desired analysis point of the sample coincides with the electron beam irradiation position. The data of the secondary electron image (or backscattered electron image) obtained at that position is stored in a table memory in association with the amount of movement. If there are multiple analysis points for a sample, these operations are performed for each analysis point.

During actual analysis, the setting means sets the sample stage to analysis mode, and the first control means controls the stage driving means based on the amount of movement stored in the table memory to move the sample stage.

At this time, the previously set analysis point and the actual analysis point may not match due to the presence of play in the sample stage.

Therefore, after the sample stage is moved, the image data is collected again, and the image comparison section compares and matches this image data with the image data obtained by referring to the table memory to determine the degree of coincidence. Then, the sample fine movement means is controlled by the second control means to finely move the sample so that the comparison output of the image comparison section is minimized. When the comparison output of the image comparison section becomes the minimum, it is determined that the current analysis point position completely matches the previously set analysis point position, and from then on, characteristic X-rays from the sample are detected. analysis is performed.

Embodiment> FIG. 1 is a configuration diagram of an X-ray microanalyzer according to an embodiment of the present invention.

In the figure, reference numeral 1 indicates the entire X-ray microanalyzer, S indicates a sample, and 2 indicates a sample stage on which the sample S is placed.
It is provided so as to be movable in the axial direction. 4 is a stage driving means for individually driving the sample stage 2 in each axis direction, and in this example, pulse motors 4 lx, 4 1y14
1z and driver 4 that generates drive pulses 2x, 4
It consists of 2y, 4 2z. 5x, 5y, 5z are driver 4 2x. This is a counter that counts the output pulses of 42Y and 42Z.

6 is an electron gun that irradiates the sample S with an electron beam, 8 is an objective lens, and lO is a scanning means that two-dimensionally scans the electron beam from the electron gun 6, which includes a deflection coil lOa and a sweep signal generator that generates a sweep signal. Consisting of 10b.

12 is a detector consisting of a secondary electron multiplier tube or the like for detecting secondary electrons from the sample S, and 14 is an amplifier for outputting a detection signal. Reference numeral I6 denotes a sample fine movement means for slightly moving the sample S, and in this example, it is composed of a piezo element 16a placed in contact with the sample S and a fine movement voltage output terminal 16b for applying a predetermined voltage to the piezo element 16a. . 18 and 20 are A/D converters, and 22 is a D/A converter. Reference numeral 24 denotes a microcomputer, and the microcomputer 24 includes a setting means 26 consisting of a keyboard or the like for setting a position registration mode for registering an analysis point and an analysis mode for moving a sample to an analysis point registered at the time of analysis, respectively; A binarization circuit 28 that binarizes the secondary electron detection signal detected by the device 12
and the image memory 30 that stores this binarized image data, and the amount of movement of the sample stage 2 from the reference position by the stage driving means 4 in the position registration mode set by the setting means 26, and the amount below this movement amount. a table memory 32 that stores the numbers of image data obtained in association with each other;
a first control means 34a that controls the stage driving means 4 based on the movement amount data stored in the table memory 32 in the analysis mode set by the setting means 26;
an image comparison unit 36 that compares and collates the image data obtained at the sample position moved by the first control means 34a and the image data obtained by referring to the table memory 32 to determine the degree of coincidence; and second control means 34b for controlling the sample fine movement means l6 so that the comparison output of 36 is minimized. In addition, the above first,
The second control means 34a, 34b are provided in a controller 34 composed of a QPU. 38 is image memory 3
This is a display device such as a CRT monitor that displays image data stored in 0.

Next, a control operation for moving the X-ray microanalyzer 1 configured as described above to the analysis position will be explained.

To perform automatic analysis, the setting means 26 sets the location registration mode in advance. Then, the scanning means 1O scans the electron beam two-dimensionally in response to a control signal from the controller 34, and data of a secondary electron (SEM) image obtained based on the detection output detected by the detector I2 is stored in the image memory 3o. Store in. The contents of this image memory 30 are then read out by the controller 34 and displayed on the display 34.

While viewing the secondary electron image displayed on the display 38, the operator operates the setting means 26 to operate the stage driving means 4, as shown in FIG.

Then, the sample stage 2 is moved so that the desired analysis point A of the sample S coincides with the irradiation position of the electron beam. At that time, the movement of the sample stage 2 from the reference position 0 ffi (xo
, y0, zo) are counters 5 x, 5 ys 5
As shown in FIG. For example, "Ol" are stored in the table memory 32 in association with each other. If there are multiple analysis points for the sample S, these operations are executed for each analysis point, and the image data is stored in the image memory 3.
0, the number and movement amount data corresponding to this image data are respectively stored in the table memory 32.

When performing actual analysis, the setting means 26 sets the analysis mode. Then, the first control means 34a of the controller 34 first controls the stage drive means 4 based on the data of one movement amount (KO% Yo, Zo) stored in the table memory 32 to move the sample stage 2. is moved to a position corresponding to this movement amount (XO, Was Zo). At this time, due to the presence of play in the sample stage 2, etc., the previously set analysis point A may not coincide with the analysis point to which the electron beam is actually irradiated.

Therefore, after the sample stage 2 is moved based on the movement m (Xo-% y.s Zo), the setting means 26 is operated to collect image data again and store it in the image memory 30. Next, the controller 34 refers to the image data number Ol at the time of setting the analysis point A, which is stored in advance in the table memory 32, and stores the corresponding image data in the image memory 3.
Read from 0. In parallel with this, the latest image data currently obtained is read from the image memory 30. Then, the image comparison unit 36 compares and matches the image data at the time of setting the previous movement amount with the currently obtained image data to determine the degree of coincidence. This degree of matching is determined, for example, by determining whether the difference between both image data is the minimum. If the difference is not the minimum, the second control means 34b controls the sample fine movement means 16 to finely move the sample S based on the comparison output of the image comparator 36.

That is, the sample S is directly moved slightly by the piezo element 16a without moving the sample stage 2. Then, in the same manner as described above, the image comparison section 36 compares both the old and new image data so that the comparison output of the image comparison section 36 is minimized. When the output of the image comparison unit 36 becomes the minimum, it can be determined that the position of the current analysis point completely matches the position of analysis point 8 set earlier.
An analysis is performed to detect the If there are multiple analysis points for the sample S, these operations are performed for each analysis point.

In this embodiment, secondary electrons are detected, but it is of course possible to detect reflected electrons in a similar manner.

Effects of the Invention> According to the present invention, the position of the actual analysis point always matches the position of the preset analysis point, so the position reproducibility is improved compared to the conventional method. Therefore, excellent effects such as being able to perform automatic analysis at high magnification with high accuracy are exhibited.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an X-ray microanalyzer according to an embodiment of the present invention, FIG. 2 is a memory map diagram for explaining the contents of a table memory, and FIG. 3 is an explanatory diagram of movement of a sample stage. 1...X-ray microanalyzer, S...sample, 2.
... Sample stage, 4... Stage drive means, IO
... Scanning means, l2 ... Detector, l6 ... Sample fine movement means, 24 ... Microcomputer, 26 ... Setting means, 28 ... Binarization circuit, 30 ... Image memory, 32...Table memory, 34a...First control means, 34b...Second control means, 36...Image comparison unit, 38...Display device.

Claims (1)

[Claims] (1) A sample stage for mounting a sample that is movable in three axial directions, a stage driving means that drives the sample stage individually in each axis direction, and an electron gun that irradiates the sample with an electron beam. , a scanning means for two-dimensionally scanning the electron beam from the electron gun, a detector for detecting secondary electrons (or reflected electrons) from the sample, and a detection signal detected by this detector being stored as image data. In the X-ray microanalyzer, the X-ray microanalyzer is equipped with an image memory for displaying data in the image memory, and a display for displaying data in the image memory as an image, the sample fine movement means having a fine movement element for finely moving the sample, a position registration mode for registering analysis points, and an analysis point. a setting means for setting an analysis mode in which the sample is moved to the registered analysis point; and a setting means for setting an analysis mode in which the sample is moved to the registered analysis point; a table memory for storing the stage in association with each other; a first control means for controlling the stage drive means based on the movement amount data stored in the table memory in the analysis mode; an image comparison section that compares and matches the image data obtained at the sample position and the image data obtained by referring to the table memory to determine the degree of coincidence; An X-ray microanalyzer comprising: second control means for controlling sample fine movement means.