JP2000180392A - Electron beam microanalyser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate the elemental distribution of a sample in an electron beam microanalyser. SOLUTION: An electron beam microanalyser performing the elemental analysis of the surface of a sample S by X-rays emitted from the sample S irradiated with electron beam 71 is equipped with an electron beam scanning part 2 performing the fast secondary scanning on the sample by the electron beam 71, an X-ray spectroscope scanning part 3 performing the scanning of the spectral wavelength of an X-ray spectroscope 4 and a control part 5 controlling both of the electron beam scanning part 2 and the X-ray spectroscope scanning part 3 at the same time. By the simultaneous control of the electron beam scanning part 2 and the X-ray spectroscope scanning part 3 by the control part 5, a secondary X-ray signal at a scanned spectral wavelength is calculated to obtain a secondary X-ray scanning image of a predetermined wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electron beam microanalyzer, and more particularly, to an electron beam microanalyzer for performing surface analysis.

[0002]

2. Description of the Related Art Analysis using an electron beam microanalyzer includes point analysis for analyzing one point on a sample surface, line analysis and surface analysis (mapping analysis) for analyzing one or two dimensions on a sample surface. . Conventionally, surface analysis is performed by scanning a wavelength of an X-ray spectrometer while continuously irradiating one point of a sample with an electron beam, and then fixing the wavelength to a specific wavelength. Dimensional scanning or electron beam
The sample stage (X,
The two-dimensional distribution of the target element is determined by two-dimensional scanning of the (Y, Z stage).

[0003]

The surface analysis is sometimes performed as a stage prior to performing the detailed analysis, in order to obtain the element distribution over a wide range of the analysis sample. In the conventional surface analysis, as described above, since two operations of the fixing operation of the analysis wavelength to the set wavelength and the two-dimensional scanning operation of the electron beam or the sample stage at the set wavelength are repeated,
There is a problem that it takes a long time to obtain a two-dimensional distribution of elements over the entire surface of the sample.

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems and to obtain the element distribution of a sample in a short time in an electron beam microanalyzer.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an electron beam microanalyzer for performing elemental analysis of a sample surface by X-rays emitted from the sample by irradiation of an electron beam.
An electron beam scanning unit for performing high-speed two-dimensional scanning of an electron beam on a sample, an X-ray spectroscope scanning unit for scanning a spectral wavelength of an X-ray spectroscope, and an electron beam scanning unit and an X-ray spectroscope scanning unit.
And a control unit for simultaneously controlling the two scanning units. The control unit simultaneously controls the electron beam scanning unit and the X-ray spectroscope scanning unit to obtain a two-dimensional X-ray signal at the spectral wavelength to be scanned. In which a two-dimensional X-ray scanning image is obtained.

According to the electron beam microanalyzer of the present invention, the control unit simultaneously controls the two scanning units, the electron beam scanning unit and the X-ray spectroscope scanning unit, and controls the X-ray spectroscopy by controlling the X-ray spectroscope scanning unit. While changing the wavelength at which the instrument
The electron beam is two-dimensionally scanned on the sample at a high speed by controlling the electron beam scanning unit. By controlling the two scans, a two-dimensional X-ray signal at each spectral wavelength can be obtained at high speed to obtain a two-dimensional X-ray scan image, and the element distribution of the sample can be obtained in a short time.

When irradiating the sample to be analyzed with the electron beam emitted from the electron beam source, the electron beam scanning unit irradiates the electron beam in the X and Y directions by electromagnetic action to irradiate the sample on the sample surface. The point is moved, causing the electron beam to scan over the sample surface. For the high-speed scanning by the electron beam scanning unit, for example, a scanning mode called a TV scan can be applied, and data for 33 screens per second can be obtained.

X-rays (characteristic X-rays) generated from the sample by the irradiated electron beam are separated by an X-ray spectroscope, and the separated X-rays of a specific wavelength are detected by an X-ray detector. X
The X-ray spectroscope scanning unit changes the wavelength to be split by the X-ray spectroscope and performs a wavelength scanning operation. By simultaneously controlling the electron beam scanning unit and the X-ray spectroscope scanning unit by the control unit, the scanning of the wavelength and the scanning of the electron beam on the sample surface are simultaneously performed. In the control, since the sample surface can be scanned in a short time by the high-speed scanning of the electron beam scanning unit, the sample surface can be scanned within the time for measuring each spectral wavelength of the wavelength scanning of the X-ray spectroscope scanning unit. Can be sufficiently obtained.

The detection signal detected from the X-ray detector is a time-series analog pulse signal. In order to obtain a two-dimensional X-ray scan image from this detection signal, the level of the detection signal is determined by a predetermined threshold value, converted into a pulse train having a constant peak value, and this pulse train is displayed on a display device. By displaying the pulse train for the same spectral wavelength, the element distribution corresponding to the spectral wavelength can be displayed. By repeating the scanning of the electron beam on the sample surface by the electron beam scanning unit at a high speed while changing the spectral wavelength by the X-ray spectroscope scanning unit, the element distribution of different elements can be sequentially obtained.

[0010] The electron beam microanalyzer of the present invention can be provided with an electron beam detector for detecting two-dimensional electrons and reflected electrons generated by irradiation of an electron beam. The electron beam detector can obtain a two-dimensional electron image by scanning the electron beam with the electron beam scanner.
The two-dimensional X-ray scan image can be superimposed and displayed on the same display screen in real time by synthesizing the image with the two-dimensional electronic image. According to the present invention, the outline of the element distribution of the sample can be grasped in a short time by performing the two-dimensional scanning of the electron beam at a high speed. For this reason, an efficient analysis is attained by grasping | ascertaining the outline of element distribution, calculating | requiring optimal analysis conditions, and performing detailed analysis.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic block diagram of a configuration example of the electron beam microanalyzer of the present invention. In the electron beam microanalyzer 1 shown in FIG. 1, an electron beam 71 generated from an electron beam generator 7 including a filament and the like is irradiated on a sample S placed on a sample stage (not shown) via a condenser lens or an objective lens (not shown). Is done. The X-ray emitted from the sample S is
Dispersion element 42 for separating light by wavelength and characteristic X-ray 4 separated
1 is detected by the X-ray spectroscope 4 including the X-ray detector 43 that detects the light. The analog pulse-like detection signal detected by the X-ray spectrometer 4 is amplified by a preamplifier 44, then identified by a predetermined threshold in a waveform shaping unit 45, and converted into a pulse signal. The peak value of the converted pulse signal is
For example, the TTL level can be set.

The electron beam scanning unit 2 deflects the electron beam 71 generated by the electron beam generating unit 7 in the X and Y directions, and scans the electron beam 71 irradiating the sample S. The electron beam scanning unit 2 controls beam scanning by a control signal output from the control unit 5. Further, the X-ray spectroscope scanning unit 3 changes the spectral wavelength of the X-ray spectroscope 4 and
Scan at the wavelength of The X-ray spectroscope scanning unit 3 controls the spectral scanning by a control signal output from the control unit 5. Therefore, the control unit 5 controls both the electron beam scanning unit 2 and the X-ray spectroscope scanning unit 3, and simultaneously controls the wavelength scanning and the electron beam scanning on the sample surface.

The pulse signal output from the waveform shaping unit 45 can be displayed on a display unit 6 such as a CRT. The display unit 6 inputs a scanning signal from the electron beam scanning unit 2 as a synchronization signal and performs synchronization in order to perform display in conjunction with the scanning of the electron beam 71. The time-series pulse signal obtained from the waveform shaping unit 45 corresponds to the element distribution obtained by scanning on the sample S, and the X-ray image displayed on the display unit 6 represents the distribution of the element corresponding to the spectral wavelength. ing.

In displaying the element distribution by the X-ray image, the element distribution can be displayed for each element, or each element distribution can be displayed simultaneously on the same screen. The display of the X-ray image can be performed by synchronizing the time-series pulse signal obtained by the scanning of the electron beam with the scanning of the electron beam. The data can be stored together with the Y coordinate data and displayed by reading the data.

Further, the electron beam microanalyzer 1
In addition to obtaining and displaying the element distribution by the X-ray detection and the X-ray detection, an electron beam such as a secondary electron beam or a reflected electron beam can be detected, and an electron beam image by the electron beam can be displayed. As a configuration for detecting this electron beam, an electron beam detection unit 81 for detecting a secondary electron beam, a reflected electron beam, or the like, amplifies the detection signal of the electron beam detection unit 81 to a predetermined voltage level of, for example, ± 1V. A preamplifier 82 and an amplifier 83 can be provided. The detected electron beam can be displayed on the display unit 6 as an electron beam image. Note that the detection sensitivity of the electron beam detector 81 is controlled by the brightness controller 8 controlled by the controller 5. In the display of the display unit 6, the X-ray image and the electron beam image can be displayed independently, or the X-ray image and the electron beam image can be displayed in a superimposed manner.

Next, the operation of obtaining the element distribution by the electron beam microanalyzer according to the present invention will be described with reference to the flowchart of FIG. The control unit 5 performs spectral scanning control on the X-ray spectroscope scanning unit 3 and operates the X-ray spectroscope 4 to determine the spectral wavelength λ. As a result, X-rays having the set spectral wavelength λ are incident on the X-ray detector 43, and X-rays having the wavelength λ are
A line is detected. The spectral wavelength λ is sequentially changed under the control of the X-ray spectroscope scanning unit 3, and scanning of the spectral wavelength is performed up to the final spectral wavelength in step S2 (step S2).
1).

Simultaneously with the scanning of the spectral wavelength by the X-ray spectroscope scanning unit 3, the electron beam is scanned over the sample S by the electron beam scanning unit 2 at a high speed.
To detect an X-ray signal. FIG. 3 is a schematic diagram for explaining the scanning state of the electron beam. 3, the electron beam scans a scanning area C on the sample S as shown by a to j in the drawing. The X-ray detector 43 detects X-rays generated at each scanning position and outputs a detection signal. FIG.
When the elements A and B are present, the electron beam scans the portions of the elements A and B in the scanning region C, and when scanning the element A (part of the electron beams b, c, and d), X-rays of wavelength λA corresponding to A are generated, and when scanning element B (part of electron beams f, g, and h), X-rays of wavelength λB corresponding to element B are generated.

FIGS. 4 and 5 are diagrams for explaining the display using the X-ray signal and the processed signal. FIG. 4 shows the case of the element A, and FIG. 5 shows the case of the element B. In FIGS. 4 and 5, the interval between X-ray signals and the pulse height are random. When the spectral wavelength of the X-ray spectroscope 4 is the wavelength λA corresponding to the element A, b, c,
When the electron beam shown by d scans the portion of the element A, the X-ray detector 43 detects the X-ray signals shown by FIGS. 4C and 4E. The X-ray signal is a time-series signal in the form of an analog pulse, and a portion having a peak value equal to or higher than a predetermined value indicates a position in the scanning direction on the sample S where the element A exists. The portion of the X-ray signal shown in FIG.
Corresponding to the scanning electron beams a, e, f, g, h, i, j in the figure, indicating that the element A does not exist. FIG.
The peak values below the predetermined value in (c) and (e) also indicate that the element A does not exist (step S3).

The waveform shaping section 45 compares the pulse height of the X-ray signal obtained in step S3 with a threshold value and converts it into a pulse signal having a predetermined peak value. The threshold value is a value for determining the presence or absence of the target element, and is set in advance according to the sensitivity of the detector.

FIGS. 4B, 4D, and 4F show converted pulses obtained by comparing the X-ray signals of FIGS. 4A, 4C, and 4E with threshold values, respectively. The signal is shown. FIG.
(B) shows no X-ray signal having a peak value equal to or higher than the threshold value,
No pulse signal is output. In contrast, FIG.
In (d) and (f), a pulse signal is output by an X-ray signal having a peak value equal to or higher than a threshold value. The length of the output pulse signal train corresponds to the length in the scanning direction where the element A exists in the scanning region C (step S4).

The black circles in FIG. 4 (g) correspond to FIG. 4 (d),
The state where the converted pulse signal shown in (f) is displayed on the display unit 6 is shown, whereby the portion where the element A exists is displayed by the region A '(step S5). When the spectral wavelength is λA, the scanning of the electron beam is repeated for a predetermined time or a predetermined number of scans, and the element A is displayed based on the X-rays of the wavelength λA obtained by the scanning (step S6). ). After step S6, the process returns to step S1 to change the spectral wavelength λ, and repeats steps S2 to S6.

By changing the spectral wavelength λ, the X-ray spectrometer 4
Is the wavelength λB corresponding to the element B,
When the electron beams indicated by f, g, and h in FIG.
X-ray signals shown in (c) and (e) are detected. The X-ray signal is a time-series signal in the form of an analog pulse, and a portion having a peak value equal to or higher than a predetermined value indicates a position in the scanning direction on the sample S where the element B exists. The portion of the X-ray signal shown in FIG. 5A is the scanning electron beams a to e in FIG.
This corresponds to i and j, and indicates that the element B does not exist. 5 (c) and 5 (e), the portion having a peak value equal to or less than the predetermined value also indicates that the element B does not exist (step S3).

The waveform shaping section 45 compares the pulse height of the X-ray signal obtained in step S3 with the threshold value of the target element B, and converts it into a pulse signal having a predetermined peak value. FIG.
(B), (d) and (f) of FIG.
The converted pulse signals obtained by comparing the X-ray signals of (c) and (e) with a threshold are shown. In FIG. 5B, there is no X-ray signal having a peak value equal to or higher than the threshold value, and no pulse signal is output. On the other hand, in FIGS. 5D and 5F, a pulse signal is output by an X-ray signal having a peak value equal to or higher than the threshold value. The length of the output pulse signal train corresponds to the length in the scanning direction in which the element B exists in the scanning region C (step S4).

The black circles in FIG. 5 (g) correspond to FIG. 5 (d),
A state in which the converted pulse signal shown in (f) is displayed on the display unit 6 is displayed, and a portion where the element B is present is displayed by a region B '(step S5). For the case where the spectral wavelength is λB, the scanning of the electron beam is repeated for a predetermined time or a predetermined number of scans, and the element B is displayed based on the X-rays of the wavelength λB obtained by the scanning (step S6). ).

FIG. 6 shows a state in which the regions A 'and B' obtained for the elements A and B are displayed on the same display screen. Note that the region A ′ and the region B ′ can be displayed by being distinguished by colors or the like. FIG. 7 shows that Al,
It is a display example when each element of Mg and Na is set as an element to be analyzed. According to the flowchart described above, Al,
Spectral wavelengths λAl, λMg, λ corresponding to each element of Mg and Na
By obtaining a two-dimensional X-ray scan image of the detection signal with Na, the respective element distribution diagrams of FIGS. 7A, 7B, and 7C can be obtained.

Each of the element distributions in FIGS. 7A, 7B and 7C is obtained by storing data of each element distribution and overlapping these element distributions by data processing. As shown in FIG. 8B, they can be displayed on the same display screen. At this time, FIG.
An electron beam image as shown in (a) is obtained in advance and can be superimposed and displayed on the element distribution diagram. In FIG. 7,
The dashed line virtually indicates the boundary by the electron beam image.

According to the embodiment of the present invention, the element distribution can be obtained in a short time, and the presence or absence of a specific element can be determined in a short time. Before the detailed analysis,
Since the analysis conditions can be grasped, the time for the detailed analysis work can be reduced. In addition, the scanning speed of the electron beam is not limited to the TV scan of 33 screens / sec.
The analysis effect of the element distribution according to the present invention in a short time can be obtained.

[0028]

As described above, according to the present invention,
The element distribution of a sample can be obtained in a short time by an electron beam microanalyzer.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a configuration example of an electronic microanalyzer of the present invention.

FIG. 2 is a flowchart for explaining an operation for obtaining an element distribution by the electron beam microanalyzer of the present invention.

FIG. 3 is a schematic diagram for explaining a scanning state of an electron beam according to the present invention.

FIG. 4 is a view for explaining an X-ray signal obtained by detecting an element A according to the present invention and a display by a processing signal.

FIG. 5 is a diagram for explaining an X-ray signal obtained by detecting an element B according to the present invention and a display based on a processed signal.

FIG. 6 is a diagram for explaining distribution display of a plurality of elements according to the present invention.

FIG. 7 is a display example when each element of Al, Mg, and Na is an element to be analyzed.

FIG. 8 is another display example when each element of Al, Mg, and Na is an element to be analyzed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron beam micro analyzer, 2 ... Electron beam scanning part, 3 ... X-ray spectroscope scanning part, 4 ... X-ray spectroscope, 5 ... Control part, 6 ... Display part, 7 ... Electron beam generation part, 8 ... Brightness Control unit, 41: characteristic X-ray, 42: spectral element, 43:
X-ray detector, 44: preamplifier, 45: waveform shaper, 7
1. Electron beam, 81: Electron beam detector, 82: Preamplifier, S: Sample.

Claims (1)

[Claims] 1. An electron beam microanalyzer for performing elemental analysis of a sample surface by X-rays emitted from the sample by irradiation of the electron beam, an electron beam scanning unit for performing high-speed two-dimensional scanning of the electron beam on the sample, An X-ray spectroscope scanning unit that scans a spectral wavelength of the spectroscope; and a control unit that simultaneously controls two scanning units of the electron beam scanning unit and the X-ray spectroscope scanning unit. An electron beam microanalyzer that obtains a two-dimensional X-ray signal at a spectral wavelength to be scanned and obtains a two-dimensional X-ray scan image of a predetermined wavelength by simultaneous control of a scanning unit and an X-ray spectroscope scanning unit.