JPH01102839A - Electron microscope with analytical function - Google Patents

Abstract

PURPOSE:To enhance the analyzing efficiency by prohibiting taking-in of detection signals to a processing means in response to shift of an electron beam irradiating position on a specimen, and thereby minimizing the time for takein prohibition of an X-ray signal by dislocation of the specimen. CONSTITUTION:A means to perform counting of X-rays with an X-ray analyzer 9 is turned on, and counting is commenced. Image on a fluorescent plate 7 is observed, and when specimen makes a drift, a specimen fine adjusting device 8 is actuated to shift the analytical zone again to the center of fluorescent plate 7. At this time, the specimen fine adjusting device 8 emits a signal which indicates that the fine adjusting device 8 is in operation, and upon receiving this signal the X-ray counting is turned off. When the operational signal for the specimen fine adjusting device 8 has gone out, the X-ray counting is resumed. This enhances accuracy of the analytical position, and the reliability of analytical result will be enhanced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electron microscope having an analysis function.

In particular, the present invention relates to a transmission electron microscope suitable for performing X-ray source analysis.

(Prior art) As is well known, X-ray analyzers emit 5 electron beams.
It converges on about 0 to 200 people, irradiates one point on the sample for about 200 seconds, and measures the wavelength and intensity of the characteristic X-rays generated from that point to obtain an X-ray analysis spectrum.

In this case, the sample may be slightly moved by the operator during the analysis, or the sample may be deformed or moved due to thermal expansion or drying without the operator's knowledge. be.

In conventional electron microscopes with an X-ray analysis function, there is no relationship between the sample fine movement device and the X-ray analysis device, and they are usually operated independently.

(Problems to be solved by the invention) In the prior art as described above, the analysis area is 50 to 1.
As the size of the electron beam becomes smaller (the analysis area is determined by the size of the electron beam on the sample, the diameter of the electron beam will also increase
(0 to 100 people), sample movement during the analysis time becomes a problem.

In other words, if we assume that the sample moves continuously at 2A/sec, for example, 4ooA sample will have moved in 200 seconds, which means that the sample that was irradiated with the electron beam at the beginning of the analysis will have moved. The region is completely different from the region irradiated with the electron beam at the end of the analysis, and the reliability of the analysis itself is lost.

In order to avoid this, it is necessary to compensate for the movement of the sample using the sample movement device of the electron microscope, but it is difficult to perform accurate compensation manually, and analysis at an accurate fixed position is impossible. The reality is that it is extremely difficult.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a means for detecting that the sample fine movement device has been operated or is being operated. Well, we have a means to detect that the position of the sample that is irradiated with the electron beam has moved, and when relative movement between the electron beam and the sample is detected, it interrupts the X-ray counting and compensates for the sample movement. By providing a means for doing so, the accuracy of X-ray analysis position in an electron microscope is significantly improved.

(Function) Normally, the sample fine movement device of an electron microscope with an X-ray analysis function moves the sample area for analysis to the center position of the observation fluorescent screen (i.e., on the optical axis) while observing the electron microscope image. .

Next, the electron beam is narrowly focused and irradiates the analysis area on the sample. In this state, the means for performing X-ray counting in the X-ray analyzer is turned on to start counting.

The image on the fluorescent screen is observed, and if the sample moves (drifts), the sample fine movement device is operated to move the analysis area to the center position of the fluorescent screen again.

At this time, the sample fine movement device outputs a signal indicating that the fine movement device is in operation, and this signal turns off the X-ray counting. When the operation signal of the sample fine movement device disappears, counting of X-rays is restarted again.

In addition, by using appropriate pattern recognition (identity recognition of figures) and other methods, the difference in electron microscope images of the sample and/or the direction and amount of movement are detected at certain time intervals, and this movement is compensated for. The sample fine movement device can also be controlled automatically or manually.

Through such control, according to the present invention, it is possible to improve the accuracy of the analysis position and increase the reliability of the analysis results.

(Example) An embodiment of the present invention will be described below with reference to FIG.

In the figure, an electron beam 3 emitted from an electron gun 1 is converged by a converging lens 2 and irradiates a sample placed in a sample holder 4. The electron beam transmitted through the sample is magnified by an objective lens 5 and a projection lens 6, and an enlarged image of the sample is formed on a fluorescent screen 7 for observation.

The sample fine movement device 8, which has the function of moving the sample, includes, for example, a pulse motor (not shown) for driving in the X and Y directions, and is controlled by a pulse signal sent from the sample fine movement device 12. A pulse signal from the sample fine movement driving device 12 is outputted when the sample fine movement operation panel 13 is operated by an operator.

The operator can observe an enlarged image of the sample through the observation window glass 14, and can operate the sample fine movement operation panel 13 while observing this enlarged image.

Characteristics X generated when the electron beam 3 irradiates the sample
The rays are detected by the X-ray detector 9, taken in by the X-ray display device 11 via the switch 10, and the intensity and wavelength of the characteristic X-rays are measured and displayed. And based on the results,
It is possible to identify elements that generate characteristic X-rays.

In the system configured as above, when performing elemental analysis of a desired sample area, follow the steps (1) to (3) below.
Operate in this order.

(1) While observing the magnified image of the sample on the observation fluorescent screen 7, the operator operates the sample fine movement operation panel 13 to move the area for analysis to the center of the fluorescent screen 7 (that is, on the optical axis).
move it to

(2) The electron beam 3 is narrowly converged by the converging lens 2 to irradiate the analysis target area.

(3) Total time T for counting characteristic X-ray intensity. After setting on the X-ray display device 11, the switch 10 is turned on to start counting.

In this case, the electron beam 3 is usually focused on 50 to 100 people, and the counting time is often set to about 200 seconds. The drift of the sample is usually about 2 A/sec, although it depends on the strength and characteristics of the sample itself.

Therefore, unless the sample position is compensated by correction using the sample-fine movement device, the sample will move by about 400 people during the analysis time, making it impossible to perform analysis with accuracy of 100 to 50 people.

That is, as shown in Figure 2, at the start of analysis, the same figure (a
), the electron beam is correctly irradiated onto the analysis target area 16, and the electron beam spot 15 matches the analysis target area 16, but at the end of the analysis, as shown in FIG. In some cases, an area completely different from area 16 is analyzed.

Even during analysis, the operator must use the fluorescent screen 7 in the analysis area.
Since the specimen can be observed from above, it is possible to correct the position as shown in FIG. However, correction for about 50 to 100 people is delicate and requires 10 to 20 seconds.

Therefore, if left as is, erroneous analysis data will be taken into the X-ray display device 11 during this sample position correction.

In this embodiment, when the sample fine movement drive device 12 operates and a sample fine movement control signal is output, the switch 1
0 is automatically turned off.

FIG. 3 shows a time chart of the operation of this embodiment.

The switch 10 is turned on by an analysis start signal ST from the X-ray display device 11, and starts receiving signals from the X-ray detector 9.

When sample drift occurs and the operator is correcting this using the sample fine movement device 8, the sample fine movement control signal CON is
occurs. Then, while this sample micro-movement control signal CON is present, the switch is turned off, and signal acquisition from the X-ray detector 9 is stopped.

When the sample fine movement control signal CON disappears, or after that time τ (time until the sample settles down, usually 2 to 3
seconds), the switch 10 is turned on and the acquisition of X-ray signals is started again. Then, when the cumulative total of the X-ray acquisition time (τl+τ2+τ3) becomes equal to τ0, the switch 10 is turned off and one analysis is completed.

With this configuration, it is possible to accumulate X-ray signals only from the target area, so the analysis position accuracy is greatly improved and the reliability of the analysis results is also improved.

In the above description, it has been described that the movement of the sample position is detected by the operator's observation of an electron microscope image, but the detection of the movement of the sample position can also be zero-motioned as described below.

That is, as shown by the dotted line in FIG. 1, an electron microscope image on the observation fluorescent screen 7 is captured by the TV left camera 1 and stored in the image memory 22.

By repeating imaging at scheduled time intervals (for example, every few seconds to 10-odd seconds) and comparing and contrasting the previous TV image and the current one using an appropriate method in the image processing device 23, it can be determined that the sample has moved ( and, if necessary, the direction of movement)
can be detected.

If movement of the sample is detected, turn off the switch 10.
In addition to generating control signals, alarms and displays are also generated to notify the operator. When the operator has readjusted the sample position and set it to the correct target position, the control signal that turns off switch 10 is extinguished.

Further, when the direction and amount of sample movement are detected in the image processing device 23, these detection results are fed back to the sample fine movement drive device 12, and automatic fine movement control of the sample position is performed to compensate and offset this. For example, X-ray analysis can be performed without substantially shifting the sample position. In this case, the time during which X-ray signal acquisition is prohibited can be minimized and the efficiency of analysis products can be increased.

Furthermore, those skilled in the art will readily understand that the present invention is applicable not only to X-ray analysis but also to electron beam analysis and the like.

(Effects of the Invention) According to the present invention, it is possible to substantially eliminate the influence of sample drift during analysis time, and therefore it is possible to improve analysis accuracy by making the analysis position accuracy the same as the electron beam spot diameter. .

In addition, automatic detection of specimen drift can reduce operator labor, and automatic correction of specimen drift can be performed by feeding back the results of automatic detection. The efficiency of analysis can be improved by minimizing the inhibition time (ie, analysis down time).

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention. FIG. 2 is a plan view of the fluorescent screen for explaining the analysis area and the influence of drift. Figure 3 shows the sample fine movement control signal and
It is a time chart showing ON and OFF states of the line intake switch. DESCRIPTION OF SYMBOLS 1... Electron gun, 3... Electron beam, 4... Sample holder, 5... Objective lens, 6... Projection lens, 7...
- Fluorescent screen for observation, 8... Sample fine movement device, 9... X-ray detector, 10... Switch, 11... X-ray display device, 12... Sample fine movement drive device, 13... Sample fine movement operation panel, 15... Electron beam spot, 16... Analysis target area, 21... TV right camera 22... Image memory,
23... Image processing device

Claims (3)

[Claims] (1) A means for converging an electron beam to irradiate the sample, a means for detecting at least one of a secondary electron beam, an X-ray, etc. generated from the sample by electron beam irradiation, and a means for capturing the detection signal. means for performing predetermined processing on the sample, and means for slightly moving the sample;
and means for generating an electron microscope image of a portion of a sample irradiated with an electron beam, the processing means detecting the movement of the electron beam irradiation position on the sample. An electron microscope with an analysis function characterized by being equipped with a means for prohibiting signal acquisition. (2) The electron microscope with analysis function according to claim 1, wherein movement of the electron beam irradiation position on the sample is performed by driving a sample fine movement device. (3) A means for converging an electron beam and irradiating the sample, a means for detecting at least one of a secondary electron beam, an X-ray, etc. generated from the sample by electron beam irradiation, and a means for capturing the detection signal. means for performing predetermined processing on the sample, and means for slightly moving the sample;
An electron microscope with an analytical function, comprising: means for generating an electron microscope image of a portion of a sample irradiated with an electron beam; means for capturing and storing the electron microscope images at scheduled time intervals; The apparatus is characterized by comprising means for comparing and contrasting two stored electron microscope images to detect a difference between the two, and means for prohibiting the acquisition of a detection signal to the processing means when the difference is greater than a predetermined value. An electron microscope with analytical functions.