JPH02262040A - Automatic qualitative analysis method based on spectral data - Google Patents

Abstract

PURPOSE:To identify existing elements automatically without comparing an energy level corresponding to the peak of spectrums with a standard spectrum table by projecting a charged particle beam on a sample, separating charged electrons generated by said projection in correspondence with energy or mass, detecting a signal, and performing qualitative analysis of the sample based on the signal. CONSTITUTION:An electron EB is projected on a sample 3. Generated Auger electrons AE are separated in correspondence with energy with a spectroscope 4. A signal which is detected with a detector 5 is supplied to an AD converter 7 through an amplifier 6. The converted signal undergoes automatic qualitative analysis in a central processing unit 8. The result is stored in a memory device 9. The result is displayed on a spectrum display device 10. The background is removed from the processed signal in the CPU 8, and the peak is taken out. The position of the peak is obtained. Element-name data are read out of a table 11 wherein the element-name data corresponding to the position are stored. Whether the data correspond to the rank of the noted peak or not is judged.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for separating and detecting charged particles generated from an analysis sample according to energy or mass, and automatically qualitatively analyzing the sample based on the signals. Regarding the method.

[Prior Art] Conventionally, a sample is irradiated with an electron beam, and Auger electrons are separated from among the charged particles generated by the sample according to their energy using a cylindrical mirror spectrometer or the like.
Auger electron spectroscopy devices are known in which the Auger electrons are detected by a detector and a spectrum is displayed on a display device or a recording device based on the signal detected by the detector.

By the way, in Auger electron spectroscopy, the observer observes the Auger spectrum (
The existing elements were identified by reading the energy level corresponding to the peak appearance position of the spectrum from a vector recorded on chart paper, etc., and comparing the read energy level with a standard spectrum table. .

[Problems to be Solved by the Invention] When performing qualitative analysis of an unknown sample using the Auger electron spectrometer as described above, for example, when analyzing samples such as alloys or compounds, a series of peaks may appear in the Auger spectrum. However, they often exhibit complex spectral structures with overlapping peaks. Therefore, it is extremely difficult for an inexperienced person to read the energy levels corresponding to elemental peaks from such a complex spectrum and identify the existing elements.

The present invention takes the above-mentioned problems into consideration and aims to provide an automatic qualitative analysis method based on spectral information that can automatically identify a detected element based on a detected peak.

[Means for Solving the Problems] The present invention irradiates a sample with a charged particle beam, separates the charged particles generated from the sample according to energy or mass, detects a signal, and detects a signal based on the signal. In a method for qualitative analysis, peaks are detected based on the detection signal, the detected peaks are classified according to the magnitude of peak intensity, and a corresponding peak position is determined for each of the classified peaks. The element core is read out from pre-stored information, and the detected peak position of the read element, the standard position of its family peak, and rank information indicating the intensity ranking within the family of the detected peak are stored in advance. The rank of the detected peak is checked, and it is determined whether the detected peak has a rank such that it has other family peaks of the same or higher intensity, and if the determination is positive, the rank of the detected peak is determined. In some cases, the presence of the read element is determined based on information as to whether a family peak of the detected peak exists in the detected peaks and classification information made at the time of detection of the detected peak. It is characterized by the following.

[Embodiments] Hereinafter, embodiments of the present invention will be described based on the drawings. 1st
The figure is a flowchart for explaining one embodiment of the present invention, Figure 2 is a diagram showing an example of an apparatus for carrying out the present invention, and Figure 3 is information on element cores with respect to peak positions (energy values). A diagram to explain a table that stores
Figure 4 is a diagram to explain a table storing information on Auger electron peak positions (energy values) for each elemental core data, Figure 5 is a diagram to explain operations, and Figure 7 is a diagram to explain ranks. This is a diagram for

In FIG. 2, 1 is an electron gun, 2 is a focusing lens for focusing the electron beam EB from the electron gun 1, and 3 is a focusing lens 2.
4 is a cylindrical mirror type spectrometer for dispersing Auger electrons AE generated from the sample 3 by irradiation with the electron beam EB according to energy; 5 is a spectrometer 4; 6 is an amplifier for amplifying the signal of the detector; 7 is an A-D converter for A-D converting the signal amplified by the amplifier 6; 8
is the central processing unit. The digital signal converted by the A/D converter 7 is supplied to a storage device 9 via a central processing unit 8. A spectrum display device 10 is connected to the central processing unit 8 via a pass line, and a table (memory) stores information on elemental cores for peak positions (energy values) as shown in FIG. 11 and a table (memory) 12 that stores rank information, which is information about the Auger electron peak position (energy value) for each elemental core and the standard value of the appearance intensity of each peak, as shown in FIG.

In an apparatus having such a configuration, a sample 3 is irradiated with an electron beam EB, Auger electrons AE generated from the sample 3 are separated according to energy by a spectrometer 4, and the Auger electrons AE are detected by a detector 5. The obtained signal is supplied to an A/D converter 7 via an amplifier 6. And the A-D
The signal from converter 7 is stored in storage device 9 via central processing unit 8 .

Here, the signals stored in the storage device 9 are automatically qualitatively analyzed by the central processing unit 8 in the following steps, and the results are displayed on the spectrum display device 10.

As shown in step 1 of the flowchart of FIG. 1, the central processing unit 8 first reads out the signals stored in the storage device 9 using a preset program, and performs signal processing such as quadratic differentiation on all detected signals. The background is removed from the processed signal and the peaks are extracted.

Next, the central processing unit 8 detects the peak position from the extracted peaks, as shown in step 2 of the flowchart of FIG.

Then, as shown in step 3, from the table 11 in which elemental core data corresponding to the peak positions are stored, 2 to 3 eV before and after each peak position detected in step 2 is determined.
Element core data within the ROI is read out.

Further, as shown in step 4, the Auger electron peak of the element read out in step 3 from the table 12 in which the position (energy value) of the Auger electron peak of all elements and the rank information of each peak are stored as a set. A set of position and rank information is read out.

Here, as shown in FIG. 7, the rank information includes peaks with no family peaks (rank 1),
Those with family peaks with lower intensity than themselves (rank 2), those with family peaks with the same intensity as themselves (rank 3), and those with family peaks with greater intensity than themselves. (Rank 4).

Then, as shown in step 5, based on the position and rank information of the Auger electron peak read out in the previous step 4, it is determined whether the rank of the peak of interest is a rank that has a family peak with an intensity equal to or higher than that of the peak. It is determined whether

In step 5, if the peak of interest has a rank that has a family peak with an intensity equal to or higher than that of the peak, as shown in step 6, whether or not the family peak exists among the detected peaks. is determined. If a family peak is found, it is determined in step 7 that the element read out by the peak of interest exists.

As a result of the judgment in step 6, if no family peak is found among the detected peaks, in the next step 6' the classification of the peak of interest when it is actually detected is major (the peak intensity is determined by the preset standard). (greater than the value a). If this determination is affirmative, a determination result that only suggests the possibility of the element's existence is output; if the determination is negative, it is determined that the element does not exist.

In addition, if the detected peak in step 5 does not have a rank that has a family peak with an intensity equal to or higher than that of the detected peak, as shown in step 8, the classification of the peak of interest when actually detected is major or overlap. It is determined whether or not (there are overlapping peaks whose peak intensities are greater than a preset reference value a).

In step 8, if the classification at the time of peak detection is major or overlap, in step 9 a determination result is output that the element of the read element core data exists at the peak position of interest.

In addition, in step 8, if the peak intensity is not major or overlapped, that is, if it is minor (the peak intensity is smaller than a preset reference value a), step 10 is performed, in which the read element core is placed at the peak position of interest. Since the existence of the element in the data is uncertain, a judgment result that only suggests the possibility of the element's existence is output.

Then, each of the above judgment results is displayed on the spectrum display device 10 along with each peak of the Auger electron spectrum as shown in FIG.
It is displayed as shown in d).

Next, specific operations will be explained in more detail.

First, when a detection signal as shown in FIG. 5(a) is read out from the storage device 9 in step 1, the signal is subjected to signal processing such as quadratic differentiation, and the signal is as shown in FIG. 5(b). A spectrum can be obtained.

Next, in step 2, a peak is detected from the background-removed spectrum as shown in FIG. 5(C), and the position (energy value) of the peak is determined. Then, as shown in step 3, the element core data corresponding to the detected peak position information is shown in Table 1.
1 is read out. Here, for example, if peak position information (700, 9 eV) is detected, a small energy width of 2 to 3 eV around this value (Reglo
n or 1 interest; hereinafter referred to as ROI)
An element corresponding to the following is selected from Table 10. In this case, the element CPe (iron) is read out.

Then, as shown in step 4, a set of Auger electron peak position data and rank information of the read element core data (Fe: iron) [45 eV (rank 3), 78
eV (rank 3), 589ev (rank 3), 84
5eV (Rank 3), 700eV (Rank 3), 7
12 eV (rank 4)] is read out from table 12.

Next, as shown in step 5, the peak detected in step 4 has a rank (i.e., rank 3 or rank 4) having a family peak with an intensity equal to or higher than that of the peak.
) is determined.

In step 5, if the rank has a family peak with an intensity equal to or higher than that of the detected peak, as shown in step 6, the peak of interest (700,9eV) family peak is as shown in FIG. 5(c). It is determined whether it is actually present among all the peaks. And for example family peak (845eV) or (589eV)
If is discovered, the peak of interest (700,9eV)
The elements read out from Table 11 based on the discovery of (
It is determined that Fe (iron) is present. If the family peak is not found among all the peaks, it is determined in step 6' whether the classification regarding the height of the peak of interest (700, 9 eV) when it is actually detected is major.

In step 6', the peak of interest (700,
If the classification of the actually detected peak of 9 eV) is major, a judgment result that only suggests the tentative possibility of the existence of the element read out based on the discovery of the peak (700, 9 eV) is output. However, if there is an overlap or a minor peak, the absence of the read element is determined based on the discovery of the peak (700.9 eV).

In addition, in the determination in step 5, if the detected peak does not have a rank that has a family peak with an intensity equal to or higher than that of the peak (that is, rank 1 is rank 2), as shown in step 8, the attention peak (7
It is determined whether the classification when actually detected (00.9 eV) is major or overlap.

Then, in step 8, the peak of interest (7
00.9 eV) is actually detected and the classification is major or overlap, as shown in step 9, it is determined that the element of the read element core data exists.

Further, in step 8, the peak of interest (700
, 9 eV) is other than major and overlap, that is, minor, the existence of the element CFe (iron) read out based on the discovery of the peak (700, 9 eV) is uncertain. Therefore, the element (Pe:
A determination output suggesting only the tentative possibility of the existence of iron) is produced (step 10).

By the way, in step 3, if two or more elements are found in RO1, the elements are identified according to the flowchart shown in FIG.

First, elemental core data corresponding to information on the detected peak position is read out from the table 11. Here, for example, if peak position information (847, 4 eV) is detected, elements corresponding to the ROI within 2 to 3 eV around this value are selected from the table 11Q shown in FIG. 3. In this case, the element (Fe: iron) (F: fluorine)
(Co: cobalt) is read out.

Then, in step 4', it is determined that each of the read elements has a family peak that is equal to or higher than itself (i.e., rank 3 or rank 4), and that the family peak is a peak that is actually detected. If an element exists during the search, an operation is performed to extract the presence of that element.

Next, if it is determined in step 5-1 that the element extracted in step 4' is present, step 5
-2, the name of the existing element is output, and in step 9, it is determined that the output element is present at the peak position.

That is, the element [Fe; 84
5eV (rank 3), P; 845eV (rank 2)
, Co; 846 eV (Rank 3)], for example, if the peak of interest is Pe; 645 eV (Rank 3), the peak is Rank 3 having a family peak with the same intensity as its own peak. From this, a search is made to see if there is a family peak with an intensity equal to or higher than that of the own peak at the corresponding peak position among the detected peaks. If the determination result in step 5-1 is affirmative, the name of the existing element is output in step 5-2,
In step 9, the output source is determined, and
In step 9, it is determined that the output element is present at the peak position. On the other hand, in step 5-3,
The remaining elements P other than Fe; B45eV (rank 3)
; 845ev (rank 2), Co; 848eV (
It is determined whether the element in rank 3) is classified as a major or overlap peak, and has a rank (ie, rank 1 or 2) that does not have a family peak of rank 3 or rank 4.

If the determination result is affirmative, a determination is made in step 10 that suggests only the possibility of the presence of the element.

Further, if the determination result in step 5-3 is negative, it is determined that the element is absent.

Now, if the presence of the extracted element is not confirmed in step 5-1, step 5-4 determines whether the classification of all the elemental peaks analyzed in step 4'' is major or overlap. You can check if there is one.

If the determination result in step 5-4 is affirmative, it is determined in step 5-5 whether or not the rank has a family peak with an intensity equal to or higher than the own peak. If the rank does not have a family peak with an intensity equal to or higher than the own peak (in the case of negative), it is determined that the element with the read element name data exists as shown in step 9,
If the rank has a family peak with an intensity equal to or higher than the above (if affirmative), it is determined that the element is absent.

On the other hand, if the determination result in step 5-4 is negative, in step 5-6 it is determined whether the rank has a family peak of greater intensity than its own peak (that is, whether it is rank 4). It will be judged. In step 5-6, if the rank has a family peak with intensity greater than its own peak (if affirmative), the absence of the element is determined.

In addition, in step 5-6, if the rank does not have a family peak with an intensity greater than its own peak (in the case of negative), in Step 5-7, a family peak with an intensity equal to that of its own peak is determined. Whether the rank has a family peak of (i.e. rank 3)
is determined. In step 5-7, if the rank does not have a family peak of equivalent intensity (if negative), it is determined that the element with the read element name data exists (step 9).

Further, in step 5-7, if it is determined that the rank has family peaks of equal intensity (in the case of affirmation), in step 5-8, the step 4 is performed.
Check that there is no judgment that the element exists for all other elemental peaks detected in ''.And,
If there is no determination that an element exists, it is determined that the element having the read element name data exists (step 9).

Note that the above-described embodiment is only one embodiment of the present invention, and the present invention can be implemented with various modifications.

For example, in the above embodiment, an automatic qualitative analysis method was explained based on Auger electron spectrum information obtained by an Auger electron spectrometer. It may also be information on a mass spectrum obtained by the device.

[Effects of the Invention] As is clear from the above description, according to the present invention, peaks are detected based on a detection signal, the detected peaks are classified according to the magnitude of the peak intensity, and each of the classified peaks is The element core corresponding to the peak position is read out from the information stored in advance, and the detected peak position of the read element, the standard position of its family peak, and the intensity within the family of the detected peak are calculated. Read rank information indicating the ranking from pre-stored information, check the rank of the detected peak, and determine whether the detected peak has a rank such that it has other family peaks of equal or higher intensity. If the determination is affirmative, the read element is determined based on the information as to whether the family peak of the detected peak exists in the detected peaks and the classification information made at the time of detection of the detected peak. By determining the presence, an automatic qualitative analysis method based on spectral information is provided that can determine the presence of the read element. Therefore, existing elements can be automatically identified without the need for humans to read the energy levels corresponding to the peaks of the spectrum from chart paper or the like and correlate them with standard spectrum tables, etc., as in the past.

[Brief explanation of drawings]

Figures 1 and 6 are flowcharts for explaining the present invention in detail, Figure 2 is a diagram showing an example of an apparatus for carrying out the present invention, and Figure 3 is information on element cores with respect to peak positions. Figure 4 is a diagram to explain a table that stores information on family peak positions for each elemental core data, Figure 5 is a diagram to explain the operation, and Figure 7 is a diagram to explain the operation. The figure is a diagram for explaining ranks. 1: Electron gun 2: Focusing lens 3: Sample 4 Triangle mirror spectrometer 5: Detector 6: Amplifier 7: A-D converter 8: Central processing unit 9: Storage device 10 Varnish vector display device 11: Table 12:Table

Claims (1)

[Claims] A method in which a sample is irradiated with a charged particle beam, charged particles generated from the sample are separated according to energy or mass, a signal is detected, and the sample is qualitatively analyzed based on the signal, wherein the detected signal is Detecting peaks based on the above, classifying the detected peaks according to the magnitude of peak intensity, and reading out the element name corresponding to the peak position for each of the classified peaks from pre-stored information, Rank information indicating the detected peak position of the read element, the standard position of its family peak, and the intensity ranking of the detected peak within the family is read out from pre-stored information, and the rank of the detected peak is determined. and determines whether the detected peak has a rank such that it has other family peaks of the same or higher intensity, and if the determination is affirmative, the family peak of the detected peak is the detected peak. Automatic qualitative determination based on spectral information, characterized in that the presence of the read element is determined based on information as to whether or not it exists in the detected peak, and classification information made at the time of detection of the detected peak. Analysis method.