Calibration method, analysis device, and program

Abstract

Provided is a correction method for an analysis device using a wavelength dispersion type X-ray spectrometer. The analysis device stores standard sensitivity data including the relationship between the wavelength and intensity of characteristic X-rays generated from a standard sample. The correction method comprises the steps of: acquiring measured data, which is a result obtained by actually measuring a wavelength and an intensity, in a standard sample with respect to two or more X-rays having different characteristics; and calculating an intensity ratio (C3), which is the ratio of the intensity for the predetermined wavelength in the measured data to the intensity for the corresponding wavelength in the standard sensitivity data, and correcting the standard sensitivity data on the basis of the intensity ratio (C3).

Description

Technical Field

[0001] The present invention relates to a calibration method, an analysis device and a program, and more specifically, to an analysis device having a wavelength dispersive X-ray spectrometer, a calibration method thereof and a program thereof. Background Art

[0002] As an analysis device using a wavelength dispersive X-ray spectrometer (WDS: Wavelength Dispersive Spectrometer), an electron probe microanalyzer (EPMA: Electron Probe Micro Analyzer) is known. In EPMA, a plurality of spectroscopic crystals with different spectral wavelength ranges are used to spectrally analyze the characteristic X-rays generated by irradiating an electron beam to a sample. Then, a detector is used to detect the wavelength and intensity of the characteristic X-rays obtained by the spectral analysis. EPMA for qualitatively or quantitatively analyzing the elements contained in a sample based on the wavelength and X-ray intensity obtained in this way is disclosed in Japanese Patent Publication No. 2010-190810 (Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-190810 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] As for such EPMA, the following EPMA is known: in a typical apparatus, sensitivity data including the relationship between the wavelength and intensity of characteristic X-rays obtained by measuring a standard sample containing elements and known concentrations thereof is stored as standard sensitivity data. In such EPMA, the concentration of the element contained in the sample can be easily obtained by comparing the sensitivity data actually obtained by measuring the sample with the standard sensitivity data.

[0008] However, it is known that the sensitivity related to characteristic X-rays generated from a standard sample actually varies from device to device due to individual differences in spectroscopic crystals, detectors, etc. Therefore, when a sample is measured based on standard sensitivity data as described above, errors may occur in the measurement results.

[0009] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to improve the accuracy of measurement by reducing the influence of individual differences in an analysis device using a wavelength dispersive X-ray spectrometer.

[0010] Solutions for solving problems

[0011] The first mode of the present disclosure is a calibration method for an analysis device using a wavelength dispersive X-ray spectrometer. The analysis device stores standard sensitivity data including the relationship between the wavelength and intensity of characteristic X-rays generated from a standard sample. The calibration method includes the following steps: obtaining measured data as a result of measuring the wavelength and intensity for two or more different characteristic X-rays in the standard sample; and calculating an intensity ratio as a ratio of the intensity for a specified wavelength in the measured data to the intensity for the corresponding wavelength in the standard sensitivity data, and calibrating the standard sensitivity data based on the intensity ratio.

[0012] Effects of the Invention

[0013] According to the calibration method disclosed in the present invention, the standard sensitivity data can be calibrated based on the measured data obtained by measuring the standard sample using the analysis device. Therefore, the standard sensitivity data reflecting the individual differences of the analysis device can be obtained. Therefore, the accuracy of the measurement using the standard sensitivity data in the analysis device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram showing the structure of an analysis device according to an embodiment of the present invention.

[0015] Figure 2 This is a diagram showing an example of the hardware configuration of a computer.

[0016] Figure 3 : is a figure which shows an example of the default standard sensitivity screen.

[0017] Figure 4 This is a diagram showing an example of a measurement data acquisition screen.

[0018] Figure 5 It is a diagram showing an example of a correction coefficient setting screen.

[0019] Figure 6 It is a diagram showing an example of a calibration confirmation screen.

[0020] Figure 7 : is a figure which shows an example of the standard sensitivity screen after calibration.

[0021] Figure 8 This is a flowchart for explaining the processing related to the calibration of standard sensitivity data. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in the drawings, and their description will not be repeated.

[0023] [1. Structure of the analysis device]

[0024] Figure 1 1 is a schematic diagram showing the structure of an analysis device 100 according to an embodiment of the present invention. The analysis device 100 according to this embodiment is an X-ray analysis device that measures and analyzes a sample using WDS. The analysis device 100 is, for example, EPMA.

[0025] Reference Figure 1 According to the present embodiment, the analyzing device 100 includes a computer 1 , an irradiating unit 5 , a display 16 , and an input unit 17 .

[0026] The computer 1 controls the analyzing device 100 .

[0027] The irradiation unit 5 includes an electron gun 52, a deflection coil 53, an objective lens 54, a sample stage 57, a sample stage driving unit 50, a WDS 6, a deflection coil control unit 51, a secondary electron detection unit 55, and a reflected electron detection unit 56. The electron gun 52, the deflection coil 53, the objective lens 54, the sample stage 57, the WDS 6, the secondary electron detection unit 55, and the reflected electron detection unit 56 are disposed in an irradiation chamber 59. During the analysis of the sample S, the irradiation chamber 59 is evacuated to a state close to vacuum.

[0028] The electron gun 52 is an excitation source for generating an electron beam E. The electron beam E corresponds to an embodiment of a “charged particle beam”. The electron beam E is irradiated to an irradiation position of a sample S on a sample stage 57. A converging lens (not shown) is used to adjust the beam of the electron beam E. The deflection coil 53 forms a magnetic field by a driving current supplied from the deflection coil control unit 51. The magnetic field formed by the deflection coil 53 deflects the electron beam E. The objective lens 54 is disposed between the deflection coil 53 and the sample S disposed on the sample stage 57. The objective lens 54 focuses the electron beam E after passing through the deflection coil 53.

[0029] The sample stage 57 is a stage for placing the sample S. The sample stage 57 is driven by the sample stage driving unit 50 and is configured to be movable in a horizontal plane.

[0030] In the irradiation unit 5, the irradiation position of the electron beam E on the sample S can be two-dimensionally scanned by driving the sample stage 57 by the sample stage driving unit 50 and / or driving the deflection coil 53 by the deflection coil control unit 51. When the scanning range is relatively small, scanning is performed using the deflection coil 53. On the other hand, when the scanning range is relatively large, scanning is performed using the movement of the sample stage 57.

[0031] The WDS 6 is a wavelength dispersive X-ray spectrometer for detecting a detection signal of characteristic X-rays emitted from an irradiation position of the sample S.

[0032] In addition, Figure 1 In the figure, only one WDS 6 is shown, but in fact, a plurality of WDS 6 are provided in the irradiation section 5 so as to surround the sample S. Each WDS 6 has a spectroscopic crystal having a different spectroscopic wavelength range. The structure of each WDS 6 is the same except for the spectroscopic crystal.

[0033] The WDS 6 includes a spectroscopic crystal 61, a detector 62, and a slit 63. The irradiation position of the electron beam E on the sample S, the spectroscopic crystal 61, and the detector 62 are arranged on a Rowland circle (not shown).

[0034] The spectroscopic crystal 61 diffracts the characteristic X-rays emitted from the irradiation position of the sample S. The spectroscopic crystal 61 is one of crystals having different spectroscopic wavelength ranges, such as lithium fluoride (LIF), pentaerythritol (PET), rubidium phthalate (RAP), etc. The spectroscopic crystal 61 is moved and tilted on the straight line 64 by a driving mechanism (not shown).

[0035] The detector 62 is an X-ray detector that detects the characteristic X-rays diffracted by the spectroscopic crystal 61. The detector 62 is rotated as shown in the figure according to the movement of the spectroscopic crystal 61 by a driving mechanism (not shown) so that the incident angle of the characteristic X-rays relative to the spectroscopic crystal 61 and the emission angle of the diffracted X-rays relative to the spectroscopic crystal 61 satisfy the Bragg diffraction condition. In this way, the wavelength scan of the characteristic X-rays emitted from the sample S can be performed. The characteristic X-rays are detected and amplified by the detector 62 and then sent from the WDS 6 to the computer 1 as a pulsed signal. In the computer 1, the intensity of the characteristic X-rays is measured as a pulsed signal measured per unit time, usually expressed in units of cps. In addition, the structure of each WDS is not limited to the above-mentioned structure, and various structures known in the past can be adopted.

[0036] The secondary electron detection unit 55 detects a detection signal of secondary electrons emitted from the irradiation position of the sample S. The detection signal of the secondary electron detection unit 55 is transmitted to the computer 1 .

[0037] The reflected electron detection unit 56 detects a detection signal of reflected electrons emitted from the irradiation position of the sample S. The detection signal of the reflected electron detection unit 56 is sent to the computer 1 .

[0038] The deflection coil control unit 51 controls the drive current supplied to the deflection coil 53 according to the instruction from the computer 1. The deflection coil control unit 51 controls the drive current according to a predetermined drive current pattern (magnitude and change speed). Thus, the irradiation position of the electron beam E can be scanned on the sample S at a desired scanning speed.

[0039] The computer 1 is connected to the irradiation unit 5 in a communicable manner. The computer 1 generates a control signal for controlling the operation of each unit of the irradiation unit 5 according to a built-in program and table. The computer 1 outputs the generated control signal to the irradiation unit 5.

[0040] In addition, the computer 1 generates an image of the irradiation position in response to scanning of the electron beam E at the irradiation position on the sample S. Specifically, the computer 1 generates a SEM image as a secondary electron image of the irradiation position of the sample S based on the detection signal of the secondary electrons detected by the secondary electron detection unit 55. In addition, the computer 1 generates a reflected electron image of the irradiation position of the sample S based on the detection signal of the reflected electrons detected by the reflected electron detection unit 56.

[0041] The computer 1 also generates a distribution image (X-ray image) of the analysis target element at the irradiation position of the sample S based on the detection signal of the characteristic X-ray detected by the four WDS. In addition, the computer 1 receives the wavelength scan of the X-ray at the irradiation position. The computer 1 generates an X-ray spectrum based on the wavelength scan of the received X-ray. The computer 1 performs qualitative analysis and / or quantitative analysis based on the X-ray spectrum.

[0042] The display 16 is configured to be able to communicate with the computer 1. The display 16 displays images related to the control of the irradiation unit 5 according to the instructions of the computer 1. In addition, the display 16 displays a reference image for the user to refer to in order to control the irradiation position of the charged particle beam according to the instructions of the computer 1. The reference image includes at least one of an X-ray image, a SEM image, and a reflected electron image. In addition, the display 16 can also be configured to also display information related to the processing of the analysis of reflected electrons, secondary electrons, and characteristic X-rays. In such a structure, for example, the display 16 displays an X-ray spectrum and the results of qualitative analysis and quantitative analysis based on the X-ray spectrum.

[0043] Therefore, the user can provide various instructions for controlling the irradiation unit 5 to the computer 1 based on the display of the display 16. In addition, the user can use the computer 1 to analyze the data detected by the irradiation unit 5 based on the display of the display 16. That is, the user can use the display of the display 16, for example, numerical values ​​indicating observation conditions, observation images (for example, X-ray images, SEM images, reflected electron images), and graphs indicating the analysis results of the obtained characteristic X-rays, secondary electrons, and reflected electrons.

[0044] The input unit 17 is connected to the computer 1 and is capable of communicating with the computer 1. The input unit 17 is used to input a user's command to the computer 1. The input unit 17 is a pointing device, a keyboard, a touch panel, etc. The pointing device is, for example, a mouse.

[0045] As described above, the analysis device 100 is configured to irradiate an electron beam onto the surface of the sample S and detect a signal emitted from the surface of the sample S. The detection signal includes characteristic X-rays, reflected electrons, and secondary electrons having a wavelength unique to the elements contained in the surface of the sample S. In the analysis device 100, the elements present at the analysis position on the surface of the sample S can be identified and quantified by analyzing the wavelength and intensity of the detected characteristic X-rays.

[0046] In addition, in the analysis device 100, the shape and composition of the surface of the sample S can be observed based on the detected secondary electrons and reflected electrons. The user can look for the target portion to be analyzed on the surface of the sample S while observing the SEM image or reflected electron image of the irradiation position. Specifically, when the user determines that the irradiation position contains the target portion to be analyzed while observing the electron image, the user determines the target portion. The user performs qualitative analysis and quantitative analysis on the surface of the sample S of the target portion.

[0047] [2. Hardware structure]

[0048] Figure 2 1 is a diagram showing an example of the hardware configuration of the computer 1. Figure 2 The computer 1 includes a processor 10 , a memory 11 , an I / O (Input / Output) interface 13 , a communication interface 15 , a display 16 , and an input unit 17 .

[0049] The processor 10 is implemented by, for example, at least one CPU (Central Processing Unit) and controls the analysis device 100 according to a program stored in the memory 11 .

[0050] The memory 11 is implemented, for example, by a storage device such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a HDD (Hard Disk Drive). The ROM can store programs executed by the processor 10. The RAM can temporarily store data used in the execution of the program in the processor 10, and can function as a temporary data storage device used as a work area. The HDD is a non-volatile storage device. Alternatively, a semiconductor storage device such as a flash memory may be used in addition to or instead of the HDD. In addition, the above-mentioned program and / or data may also be stored in an external storage device accessible to the processor 10.

[0051] The communication interface 15 is an interface for the computer 1 to communicate with external devices wirelessly or by wire. The I / O interface 13 is an interface for inputting to or outputting from the computer 1. Figure 2 As shown, the I / O interface 13 is connected to the display 16 , the input unit 17 , and the irradiation unit 5 .

[0052] The display 16 is implemented by a display device. The input unit 17 is implemented by an input device that receives input from a user. The input unit 17 is, for example, a keyboard, a mouse, and / or a touch panel integrally formed with the display screen of the display 16 .

[0053] The computer 1 does not need to be composed of one computer, but may be composed of a plurality of computers. That is, the processing performed in the computer 1 may be performed in a distributed manner by a plurality of computers. For example, the computer 1 may be composed of a control computer that controls the irradiation unit 5 and an analysis computer that analyzes the detection signal of the X-rays detected by the irradiation unit 5. In this case, the control computer and the analysis computer may each have an input unit and a display.

[0054] [3. Comparison with conventional analysis devices]

[0055] In conventional EPMA using WDS, data including the wavelength and intensity of characteristic X-rays generated from a standard sample (hereinafter also referred to as "standard sensitivity data") can be obtained by irradiating an electron beam to a standard sample containing elements and known concentrations. EPMA is known in which sensitivity data obtained by measuring a standard sample in a representative device is stored as initial standard sensitivity data, and a standard sensitivity curve approximated based on the sensitivity data is stored and sold.

[0056] The following describes this in more detail.

[0057] The intensity of characteristic X-rays has a proportional relationship with the concentration value of the element that is the source of the X-rays and the current value of the irradiated electron beam. Therefore, when an electron beam with a known current value is irradiated to a standard sample containing a known element and its concentration and the intensity of the characteristic X-rays at this time is measured, the intensity value of the characteristic X-rays measured when the concentration of the target element is 100% can be expressed as the intensity value per unit current of the irradiated electron beam, that is, the standard sensitivity value. The standard sensitivity value is expressed as the intensity value per 1A (ampere) of irradiation current, for example, and the unit is cps / A.

[0058] By multiplying the standard sensitivity value by the irradiation current value during measurement, the intensity value that can be measured under the irradiation current condition when the target element concentration is 100%, in other words, the 100% intensity value, can be obtained. The concentration of the target element can be simply obtained by dividing the actually measured intensity value by the 100% intensity value.

[0059] Generally, there are multiple characteristic X-rays in the spectral wavelength range of a spectral crystal. It is known that characteristic X-rays are classified into Kα series, Lα series, Mα series, etc. according to the atomic nuclei that contribute to the generation of X-rays. When observed in the same series, the wavelengths of characteristic X-rays are arranged in the order of atomic numbers, and the standard sensitivity value shows a curve change with respect to the wavelength value (refer to Figure 3 Default Standard Sensitivity screen).

[0060] By utilizing such characteristics, a curve approximation of the change in the standard sensitivity value relative to the wavelength value can be performed based on a data set, i.e., standard sensitivity data, which is prepared by obtaining the wavelength and standard sensitivity value related to each characteristic X-ray for each spectroscopic crystal and then for each series of each X-ray. The curve obtained in this way is called a standard sensitivity curve. The standard sensitivity value can be calculated based on the wavelength value according to the approximate formula provided by the standard sensitivity curve. Therefore, it is also possible to assign a standard sensitivity value to a characteristic X-ray whose standard sensitivity value cannot be measured due to reasons such as difficulty in obtaining a standard sample, so as to convert the measured intensity of the characteristic X-ray into a concentration value.

[0061] In conventional EPMA using WDS, the initial standard sensitivity data is data obtained by measuring the sensitivity of characteristic X-rays in each WDS of a representative device in a company that sells EPMA, for example. In the sold source, many types of standard samples are used to measure the intensity of as many characteristic X-rays as possible, thereby setting the initial standard sensitivity data and standard sensitivity curve in a manner that accurately reflects the sensitivity of each WDS in the representative device.

[0062] In EPMA that stores standard sensitivity data and standard sensitivity curves set in this way, the elements contained in the sample and their concentrations can be obtained by comparing the wavelength and intensity of characteristic X-rays obtained by measuring the sample in each device with the standard sensitivity value obtained from the standard sensitivity curve.

[0063] However, in reality, the "sensitivity" of characteristic X-rays, that is, "the intensity of X-rays obtained when measuring a predetermined standard sample under the same conditions", varies from device to device due to individual differences in spectroscopic crystals, detectors, and other mechanisms included in WDS. Therefore, as described above, the measurement results obtained by comparing the wavelength and intensity of characteristic X-rays obtained by measuring samples in each device with the initial standard sensitivity value may contain errors.

[0064] Therefore, it is desirable that the initial standard sensitivity data and standard sensitivity curve be corrected in each device to standard sensitivity data and standard sensitivity curve that reflect the sensitivity of each device. However, the types of standard samples that users can prepare are limited, so it is very difficult to re-measure the sensitivity of all characteristic X-rays measured by the sold source in each device. In addition, the device usually has the function of updating the standard sensitivity data and standard sensitivity curve, but if the user only changes a part of the standard sensitivity data within the range that can be obtained using the standard sample he owns, the prepared standard sensitivity curve may sometimes be unnaturally deformed, which may reduce the accuracy and appropriateness of the standard sensitivity curve.

[0065] Therefore, in this embodiment, the following analysis device 100 is provided: the initial standard sensitivity data can be set as the default standard sensitivity data, the default standard sensitivity data can be corrected based on the sensitivity data obtained by actually measuring a relatively small amount of standard samples, and the standard sensitivity curve can be prepared using the result. Thus, the user can use the standard sensitivity curve that matches the characteristics of each device. Therefore, the influence of individual differences of the device on the measurement results is reduced, and the accuracy of the measurement in each device is improved.

[0066] [4. Calibration method of standard sensitivity data]

[0067] Next, the display screen ( Figure 3 to Figure 7 ) is used to explain how to calibrate the default standard sensitivity data. The user refers to this display screen to calibrate the standard sensitivity data.

[0068] In addition, in this specification, as an example of standard sensitivity data of each WDS, correction of standard sensitivity data of a WDS having a spectroscopic crystal composed of PET is described. Standard sensitivity data of WDS having other spectroscopic crystals can also be corrected in the same manner.

[0069] (4-1.Default standard sensitivity screen)

[0070] Figure 31 is a diagram showing an example of a default standard sensitivity screen. The standard sensitivity screen is a screen for displaying standard sensitivity data. The standard sensitivity screen is displayed when the user inputs an instruction for displaying the standard sensitivity screen to the analysis device 100. In one implementation example, a button for executing the display of the standard sensitivity screen is included in an operation screen (not shown) of the analysis device 100 displayed on the display 16 of the computer 1. Then, the user selects the button, whereby the standard sensitivity screen is displayed on the display 16. The selection is performed, for example, by clicking using the input unit 17.

[0071] The standard sensitivity screen includes table T1. In table T1, each row includes a data set of standard sensitivity values ​​for characteristic X-rays of the Kα series, Lα series, and Mα series, that is, standard sensitivity data, and a sensitivity chart as a chart thereof. Hereinafter, the sensitivity chart of the Kα series, the sensitivity chart of the Lα series, and the sensitivity chart of the Mα series are also referred to as "Kα chart", "Lα chart", and "Mα chart", respectively.

[0072] In each sensitivity graph, the horizontal axis represents the spectral wavelength. The vertical axis represents the intensity of characteristic X-rays (cps / A). In each sensitivity graph, a black circle such as that shown by C1 represents the default standard sensitivity data. In each sensitivity graph, the standard sensitivity data shows a curve change. Figure 3 In the example of , each sensitivity graph includes a standard sensitivity curve as shown by the dotted line L1. The standard sensitivity curve is a curve obtained by performing polynomial approximation on the standard sensitivity data. Figure 3 In the example of , the standard sensitivity curve is a cubic curve that best fits the standard sensitivity data. In this specification, the "best fit curve" refers to, for example, a curve with the smallest error with the original data. The error with the original data is obtained, for example, by the least squares method.

[0073] The user can confirm the standard sensitivity data used in the current device by referring to the standard sensitivity screen. The standard sensitivity data can be calibrated based on the measured data. In addition, in this specification, "measured data" refers to the sensitivity data obtained by measuring the standard sample in the device owned by the user.

[0074] (4-2. Actual measurement data acquisition screen)

[0075] Figure 41 is a diagram showing an example of a measured data acquisition screen. The measured data acquisition screen is a screen for acquiring measured data. The measured data acquisition screen is displayed when the user inputs an instruction for calibrating the standard sensitivity curve to the analysis device 100. In one implementation example, a button for executing the calibration of the standard sensitivity curve is included in the operation screen (not shown) of the analysis device 100 displayed on the display 16 of the computer 1. Then, the user selects the button, whereby the measured data acquisition screen is displayed on the display 16.

[0076] The measured data acquisition screen includes a table T2 and a button B1. The rows of the table T2 show the sensitivity data of the Kα series, the Lα series, and the Mα series. The table T2 includes a sensitivity graph in the left column and a sensitivity table as a table of sensitivity data in the right column.

[0077] The sensitivity tables of the Kα series, Lα series, and Mα series are also referred to as Kα tables, Lα tables, and Mα tables, respectively. Each sensitivity table contains “characteristic X-rays”, “wavelengths”, "Standard strength (cps / A)", "Measured strength (cps / A)", and "Strength ratio" items.

[0078] The item "characteristic X-ray" indicates the name of each characteristic X-ray. The name of the characteristic X-ray is indicated by an element symbol and a series. For example, the characteristic X-ray of the Kα series of silicon (element symbol Si) is indicated as "SiKα".

[0079] Project "Wavelength ” indicates the wavelength unique to this characteristic X-ray.

[0080] The item “standard intensity (cps / A)” indicates the intensity of characteristic X-rays corresponding to the wavelength in the standard sensitivity data (hereinafter also referred to as “standard intensity”).

[0081] The item “measured intensity (cps / A)” indicates the intensity of characteristic X-rays corresponding to the wavelength in the measured data (hereinafter also referred to as “measured intensity”).

[0082] The item "intensity ratio" indicates the ratio of the measured intensity to the standard intensity. In one implementation example, the intensity ratio is a value obtained by dividing the measured intensity by the standard intensity.

[0083] In one implementation example, the item "characteristic X-ray" "wavelength The value of "Standard intensity (cps / A)" is pre-displayed based on the standard sensitivity data stored in the memory 11. The value of the item "Measured intensity (cps / A)" is configured to be input by the user. The value of the item "Intensity ratio" is configured to be automatically displayed based on the value of the item "Standard intensity (cps / A)" in the same row and the value of the item "Standard intensity (cps / A)" when the value of the item "Standard intensity (cps / A)" in the same row is input.

[0084] In each sensitivity graph, the horizontal axis represents the spectral wavelength. The vertical axis represents the intensity of characteristic X-rays (cps / A). In each sensitivity graph, a black circle such as that shown by C1 represents default standard sensitivity data. In each sensitivity graph, a white circle such as that shown by C2 represents actual measurement data.

[0085] In one implementation example, the black circle indicating the standard sensitivity data as shown by C1 is displayed in advance based on the standard sensitivity data stored in the memory 11. The white circle indicating the measured data as shown by C2 is configured to be automatically displayed when the value of the item "measured intensity (cps / A)" of the sensitivity table is input.

[0086] Button B1 is a button for completing the acquisition of measured data. Button B1 is configured to display Figure 5 The correction factor setting screen is shown.

[0087] For example, the measured data acquisition screen is used as follows. The user inputs the measured intensity into the cell of the item "measured intensity (cps / A)". The input is performed by the user inputting the measured intensity based on the measured data of the standard sample stored in the memory 11. Specifically, for example, the user refers to the measured data and uses the input unit 17 to input the measured intensity. In addition, for example, it can also be configured so that when the user selects the cell of the item "measured intensity (cps / A)" corresponding to a specific characteristic X-ray, the measured intensity when the corresponding characteristic X-ray was measured in the past is automatically input.

[0088] When the user inputs the intensity corresponding to the unit of "measured intensity (cps / A)", the value of "intensity ratio" of the same row is automatically calculated. In addition, a white circle corresponding to "measured intensity (cps / A)" as shown by C2 is displayed in the sensitivity graph.

[0089] As described above, the measured data acquisition screen can be used to acquire the measured data. In addition, the user can intuitively compare the input measured intensity with the standard intensity by referring to the sensitivity graph.

[0090] When the user selects button B1 and completes the acquisition of measured data, the display Figure 5 The correction factor setting screen is shown.

[0091] (4-3. Correction coefficient setting screen)

[0092] Figure 5 : is a diagram showing an example of a correction coefficient setting screen. The correction coefficient setting screen is a screen for setting correction coefficients. The correction coefficient setting screen includes a table T3 and a button B2. In table T3, regarding the data of intensity ratio, a chart (intensity ratio chart) is included in the left column, and a table (intensity ratio table) is included in the right column.

[0093] The intensity ratio table includes "characteristic X-rays" and "wavelengths" "Intensity ratio" project. Project "Characteristic X-ray" "Wavelength "Intensity ratio" and Figure 4 The corresponding items of the sensitivity table ("Characteristic X-ray" "Wavelength "Intensity ratio") is the same as the "Characteristic X-ray" and "Wavelength" items in the intensity ratio table. "Intensity ratio" corresponding to the value, enter in Figure 4 The corresponding items ("Characteristic X-ray", "Wavelength" "Intensity ratio"). That is, for Figure 4 The characteristic X-ray with measured intensity is obtained from the sensitivity table. Figure 5 The name, wavelength, and intensity ratio of the characteristic X-ray are automatically entered into the intensity ratio table.

[0094] In the intensity ratio graph, the horizontal axis represents wavelength and the vertical axis represents intensity ratio or correction coefficient. In the intensity ratio graph, a black circle such as that shown by C3 represents the relationship between wavelength and intensity ratio in the intensity ratio table, and is automatically displayed based on the intensity ratio table.

[0095] The dotted line L2 of the intensity ratio graph is a graph obtained by performing a polynomial approximation on the intensity ratio (black circle) for the wavelength as shown by C3. The polynomial approximation is automatically performed by the processor 10 based on the relationship between the wavelength and the intensity ratio. More specifically, the coefficients of each term of the polynomial are determined in such a way as to minimize the error with the intensity ratio data, for example, using the least squares method. Figure 5 In the example of , the dotted line L2 is used to show the result obtained by the processor 10 fitting the four data points using the cubic equation. In this specification, the value obtained by performing the polynomial approximation is called the correction coefficient, and the value is used to correct the standard sensitivity data. When constructed like this, the correction coefficient can also be set for the wavelength for which the corresponding measured data is not obtained. In addition, the line representing the correction coefficient shown by the dotted line L2 in the intensity ratio chart is also referred to as the "correction coefficient line" below.

[0096] The button B2 is a button for completing the setting of the correction coefficient and confirming the result obtained by performing the correction according to the set correction coefficient. The button B2 is configured to display Figure 6 The calibration confirmation screen is shown.

[0097] As described above, the correction coefficient is set in the correction coefficient setting screen. The user can intuitively understand the intensity ratio or the value of the correction coefficient for the wavelength by referring to the intensity ratio graph. In addition, the user can confirm that the correction coefficient line is appropriately fitted to the intensity ratio.

[0098] When the user selects button B2 and completes the setting of the correction coefficient, the display Figure 6 The calibration confirmation screen is shown.

[0099] (4-4. Calibration confirmation screen)

[0100] Figure 6 The calibration confirmation screen is used by the user to confirm the calibration results. Figure 5 The calibration confirmation screen includes a table T4 and a button B3.

[0101] In Table T4, each row contains sensitivity graphs for the Kα series, Lα series, and Mα series. In each sensitivity graph, the horizontal axis represents the spectral wavelength. The vertical axis represents the intensity of characteristic X-rays (cps / A). The black circles such as those shown by C1 in each sensitivity graph represent the default standard sensitivity data. The white circles such as those shown by C4 in each sensitivity graph represent the default standard sensitivity data based on the Figure 5 Standard sensitivity data after correction using the correction factor set in .

[0102] The button B3 is a button for determining the correction of the standard sensitivity data. When the button B3 is selected, the correction of the standard sensitivity data is determined and displayed. Figure 7 The calibrated standard sensitivity screen is shown.

[0103] (4-5. Standard sensitivity screen after calibration)

[0104] Figure 7 : is a figure which shows an example of the standard sensitivity screen after correction. The standard sensitivity screen after correction includes table T5. In table T5, each row includes the sensitivity graph of Kα series, Lα series, and Mα series.

[0105] In each sensitivity graph, the horizontal axis represents the spectral wavelength. The vertical axis represents the intensity of characteristic X-rays (cps / A). In each sensitivity graph, the standard sensitivity data after correction such as that shown in C4 shows a curve change. Figure 7 In the example of , each sensitivity graph includes a corrected standard sensitivity curve as shown by the dotted line L3. The corrected standard sensitivity curve is a curve obtained by performing polynomial approximation on the corrected standard sensitivity data. Figure 7 In the example shown in Figure 2, the standard sensitivity curve is the cubic curve that best fits the standard sensitivity data.

[0106] The standard sensitivity curve is automatically calculated by the processor 10 based on the standard sensitivity data. When configured in this way, the intensity of the wavelength for the data point without the standard sensitivity data is also supplemented. Therefore, even if the characteristic X-ray of the wavelength for the data point without the corresponding standard sensitivity data is detected when the user measures the sample, the concentration of the corresponding element can be calculated using the standard sensitivity curve.

[0107] according to Figure 6 After the calibration of the standard sensitivity data is completed, when the user inputs an instruction for displaying the standard sensitivity screen to the analysis device 100, the display Figure 7 The standard sensitivity screen will replace the display Figure 3 In this way, the user can check the current standard sensitivity data by referring to the standard sensitivity screen.

[0108] [5. Correction control]

[0109] Figure 8 1 is a flowchart for explaining the processing related to the calibration of the standard sensitivity data executed by the computer 1. Figure 8 In step (hereinafter, also referred to as ST) 02, the processor 10 uses the measured data to obtain the screen ( Figure 4 ) to obtain the actual measurement data of the standard sample measured in the device held by the user.

[0110] In ST04, the processor 10 calculates an intensity ratio which is a ratio of the intensity at a predetermined wavelength in the actual measurement data to the intensity at a corresponding wavelength in the standard sensitivity data. The calculated intensity ratio is displayed as Figure 4 The sensitivity table and Figure 5 The value corresponding to the item "Intensity Ratio" of the intensity table.

[0111] In ST06, the processor 10 performs polynomial approximation on the intensity ratio for the wavelength. The result obtained by performing the polynomial approximation is Figure 5 The intensity graph is displayed as a correction coefficient line (dashed line L2).

[0112] In ST08 , the processor 10 sets the value obtained by performing the polynomial approximation as the correction coefficient.

[0113] In ST10, the processor 10 calibrates the default standard sensitivity data based on the set calibration coefficient. The calibrated standard sensitivity data is displayed on Figure 5 and Figure 6 Sensitivity chart.

[0114] In ST12, the processor 10 sets a standard sensitivity curve obtained by performing polynomial approximation on the corrected standard sensitivity data. The set standard sensitivity curve is displayed on Figure 6 When ST12 is completed, the processor 10 ends the processing.

[0115] pass Figure 8 The processing shown can correct the standard sensitivity data based on the actual measurement data obtained by measuring the standard sample in the device owned by the user. Therefore, the standard sensitivity data reflecting the individual differences of the device can be obtained. Therefore, the accuracy of the measurement using the standard sensitivity data in the analysis device can be improved.

[0116] [6.Supplementary Note]

[0117] (6-1. Polynomial approximation of correction coefficients)

[0118] like Figure 8 As shown in ST06 to ST08 of the present invention, the analysis device 100 sets the correction coefficient by performing polynomial approximation on the intensity ratio for the wavelength. In order to perform polynomial approximation on the intensity ratio, in ST04, it is necessary to obtain measured data as a result of measuring the wavelength and intensity for two or more different characteristic X-rays. "Two or more different characteristic X-rays" refers to two or more characteristic X-rays having different unique wavelengths.

[0119] In addition, the inventors found that: in this polynomial approximation, the cubic curve best fits the measured data. In other words, when the correction coefficient is set to a cubic formula, the error (e.g., mean square error) with the measured data becomes smaller. In order to properly fit using a cubic curve like this, the measured data needs to include at least 4 data points. Therefore, it is expected that in ST04, the processor 10 obtains measured data as a result of measuring the wavelength and intensity for more than 4 different characteristic X-rays. In addition, in ST06, the processor 10 approximates the intensity ratio for the wavelength as a cubic formula.

[0120] The steps of setting the correction coefficient based on the intensity ratio for the wavelength shown in ST06 to ST08 are not necessarily limited to the polynomial approximation described above. For example, the correction coefficient can be set by linearly supplementing the data points of the intensity ratio. In this case, the correction coefficient line is a line graph that linearly connects the data points. However, as the setting of the correction coefficient, the method using the polynomial approximation is more excellent.

[0121] When giving an example, in the method of linearly supplementing the intensity ratio, even if the intensity ratio data contains an extremely large or extremely small outlier due to some factors such as failure to measure the actual intensity, the correction coefficient line near the outlier also shows an extreme change. Therefore, the standard sensitivity data corrected according to the correction coefficient line is not a smooth curve, which may become a factor of measurement error. On the other hand, in the case of setting the correction coefficient by performing polynomial approximation on the intensity ratio, even if one outlier is generated in the intensity ratio data, the correction coefficient line can be smoothly set by the influence of other points despite being near the outlier. Therefore, the standard sensitivity data corrected according to the correction coefficient line also becomes a smooth curve, and the possibility of measurement error is reduced.

[0122] In addition, if the method of performing polynomial approximation is used, the standard sensitivity data can be corrected more appropriately based on the actual measurement data of the standard sample compared to other methods such as using a line graph. In addition, for example, even if about 20 kinds of standard samples attached to EPMA are used, 2 to 7 kinds of characteristic X-rays can be measured for each spectroscopic crystal, so there is an advantage that the standard sensitivity data can be corrected within this range. Therefore, the user does not need to obtain a new standard sample in order to correct the standard sensitivity data, and can easily perform the correction.

[0123] (6-2. Method for obtaining measured data)

[0124] In addition, the method of acquiring the measured data is not limited to the above example. For example, if the user inputs the value of the measured data for the characteristic wavelength of the characteristic X-ray, all subsequent calculations are not displayed on the display 16, and the standard sensitivity data is automatically corrected. Figures 5 to 8 The processing for calibrating the standard sensitivity data described in the screen of can also be performed entirely in the background. Figures 5 to 8 screen, thereby having the advantage that the user can visually confirm that the standard sensitivity data has been properly calibrated.

[0125] In addition, it can also be configured as follows: in the analysis device 100, when an instruction for correcting the standard sensitivity data is input from the user, an instruction for the standard sample set in the analysis device 100 is displayed from the analysis device 100, and if the user sets the standard sample, the analysis device 100 automatically obtains the actual measurement data and corrects the standard sensitivity data.

[0126] (6-3. Regarding the timing of calibration)

[0127] The calibration of the standard sensitivity data is performed, for example, before a user purchases the device and measures a sample to be measured. This can reduce the influence of individual differences in the device before measuring the sample and improve the accuracy of the measurement.

[0128] In addition, it is known that in an analysis device including a WDS, the sensitivity of the device changes over the years due to repeated measurements. In order to reduce the influence of this change over the years, the standard sensitivity data can also be corrected regularly (for example, once a year). In this case, the default standard sensitivity data can be corrected, and the standard sensitivity data that was corrected a little bit ago can also be corrected.

[0129] (6-4. Correction of standard sensitivity data based on standard sensitivity curve)

[0130] Furthermore, the correction of the standard sensitivity data does not necessarily need to be the correction of the data points included in the standard sensitivity data as described above, and may be, for example, the correction of the standard sensitivity curve.

[0131] The calibration of the standard sensitivity curve is performed, for example, as follows. First, the ratio of the measured intensity of the characteristic X-ray to the value of the standard sensitivity curve of the corresponding wavelength is calculated as the intensity ratio. Next, the calibration coefficient is calculated based on the intensity ratio. Then, the product of the calibration coefficient and the value of the standard sensitivity curve before calibration is recorded as the standard sensitivity curve after calibration.

[0132] With such a configuration, for example, even when the characteristic X-rays actually measured in the user's device are not included in the data points of the default standard sensitivity data, the standard sensitivity curve can be corrected. Also, for example, in a device that includes, as the default standard sensitivity data, only a standard sensitivity curve obtained by performing polynomial approximation on data points actually measured using a representative device instead of the data points, the standard sensitivity curve can be corrected.

[0133] [Way]

[0134] It will be understood by those skilled in the art that the above-mentioned multiple exemplary embodiments are specific examples of the following aspects.

[0135] (Item 1) A calibration method according to one embodiment is a calibration method for an analysis device using a wavelength dispersive X-ray spectrometer. The analysis device stores standard sensitivity data including the relationship between the wavelength and intensity of characteristic X-rays generated from a standard sample. The calibration method includes the following steps: obtaining measured data as a result of measuring the wavelength and intensity for two or more different characteristic X-rays in the standard sample; and calculating an intensity ratio as a ratio of the intensity for a specified wavelength in the measured data to the intensity for the corresponding wavelength in the standard sensitivity data, and calibrating the standard sensitivity data based on the intensity ratio.

[0136] According to the calibration method described in the first item, the standard sensitivity data can be calibrated based on the measured data obtained by measuring the standard sample by the analyzer. Therefore, the standard sensitivity data reflecting the individual differences in the sensitivity of the analyzer can be obtained. Therefore, the accuracy of the measurement using the standard sensitivity data in the analyzer can be improved.

[0137] (Item 2) In the calibration method described in Item 1, the calibration step includes the following steps: setting a calibration coefficient based on the intensity ratio; and storing the product of the calibration coefficient and standard sensitivity data before calibration as standard sensitivity data after calibration.

[0138] According to the correction method described in the second item, the correction coefficient reflecting the intensity ratio, i.e., the ratio based on the sensitivity of the device, can be reflected in the standard sensitivity data. Therefore, the standard sensitivity data reflecting the sensitivity ratio based on the device can be obtained. Therefore, the accuracy of the measurement using the standard sensitivity data in the analysis device can be improved.

[0139] (Item 3) In the correction method described in Item 2, the setting step includes the following steps: performing polynomial approximation on the intensity ratio with respect to the wavelength in the measured data; and setting the value obtained by performing the polynomial approximation as the correction coefficient.

[0140] According to the correction method described in the third item, it is also possible to set a correction coefficient for a wavelength for which no corresponding measured data is obtained. In addition, in particular, when a correction coefficient is set for a wavelength for which no corresponding measured data is obtained by polynomial approximation, the correction coefficient line can be set as a smooth curve even when outliers are included in the measured data. Therefore, when the standard sensitivity data is corrected using a correction coefficient line based on polynomial approximation, the possibility of generating a measurement error is reduced compared to a case where the standard sensitivity data is corrected using a correction coefficient line obtained by, for example, a linear complementary intensity ratio.

[0141] (Item 4) In the correction method described in Item 3, the acquisition step includes the following steps: for 4 or more different characteristic X-rays, actual measurement data as a result of actual measurement of wavelength and intensity are acquired, and the polynomial approximation step includes the following steps: approximating the intensity ratio with respect to the wavelength as a cubic expression.

[0142] The inventors found that in the polynomial approximation of the intensity ratio, the cubic curve best fits the measured data. Therefore, according to the correction method described in the fourth item, a correction coefficient line that best fits the measured data is obtained. That is, a correction coefficient that appropriately reflects the sensitivity of the analyzer can be set. By using such a correction coefficient to correct the standard sensitivity data, the accuracy of the measurement using the standard sensitivity data can be improved.

[0143] (Item 5) In the correction method described in any one of items 2 to 4, the correction step includes the following steps: setting a standard sensitivity curve obtained by performing polynomial approximation on the corrected standard sensitivity data, the standard sensitivity curve being used in the analysis device to calculate the concentration of elements contained in the sample based on the intensity of characteristic X-rays generated from the sample to be measured.

[0144] According to the calibration method described in the fifth item, the intensity of the wavelength for which there is no data point of standard sensitivity data is also supplemented. Therefore, even if the user detects a characteristic X-ray of a wavelength for which there is no corresponding data point of standard sensitivity data when measuring a sample, the concentration of the corresponding element can be calculated using the standard sensitivity curve.

[0145] (Item 6) An analysis device according to another aspect uses a wavelength dispersive X-ray spectrometer, and includes: a processor that executes the calibration method according to any one of Items 1 to 5; and a memory that stores standard sensitivity data and actual measurement data.

[0146] (Item 7) A program according to another aspect causes a computer to execute the calibration method according to any one of Items 1 to 6.

[0147] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0148] Description of Reference Numerals

[0149] 1: Computer; 5: Irradiation unit; 6: WDS; 10: Processor; 11: Memory; 13: I / O interface; 15: Communication interface; 16: Display; 17: Input unit; 50: Sample workbench drive unit; 51: Deflection coil control unit; 52: Electron gun; 53: Deflection coil; 54: Objective lens; 55: Secondary electron detection unit; 56: Reflected electron detection unit; 57: Sample workbench; 61: Spectroscopic crystal; 62: Detector; 63: Slit; 100: Analyzer; B1, B2, B3: Buttons; E: Electron beam.

Claims

1. A calibration method for an analysis device using a wavelength dispersive X-ray spectrometer, The analysis device stores standard sensitivity data including the relationship between the wavelength and intensity of characteristic X-rays generated from a standard sample. The calibration method comprises the following steps: In the standard sample, for two or more different characteristic X-rays, actual measurement data is obtained as a result of actual measurement of wavelength and intensity; as well as An intensity ratio is calculated, which is a ratio of an intensity at a predetermined wavelength in the actual measurement data to an intensity at a corresponding wavelength in the standard sensitivity data, and the standard sensitivity data is corrected based on the intensity ratio.

2. The calibration method according to claim 1, wherein: The step of correction comprises the following steps: setting a correction coefficient based on the intensity ratio; and The product of the correction coefficient and the standard sensitivity data before correction is stored as the standard sensitivity data after correction.

3. The calibration method according to claim 2, wherein: The setting steps include the following steps: performing a polynomial approximation on the intensity ratio with respect to wavelength in the measured data; and The value obtained by performing the polynomial approximation is set as the correction coefficient.

4. The calibration method according to claim 3, wherein: The step of obtaining includes the following steps: obtaining measured data as a result of measuring wavelength and intensity for more than four different characteristic X-rays, The step of polynomial approximation includes the step of approximating the intensity ratio with respect to wavelength as a cubic expression.

5. The calibration method according to any one of claims 2 to 4, wherein: The correction step includes the following steps: setting a standard sensitivity curve obtained by performing polynomial approximation on the corrected standard sensitivity data; The standard sensitivity curve is used in the analysis device to calculate the concentration of an element contained in the sample based on the intensity of characteristic X-rays generated from the sample to be measured.

6. An analysis device using a wavelength dispersive X-ray spectrometer, the analysis device comprising: A processor, which executes the correction method according to any one of claims 1 to 4; and A memory stores the standard sensitivity data and the measured data.

7. A program for causing a computer to execute the calibration method according to any one of claims 1 to 4.

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