Correction method, analysis device, and program

Abstract

This correction method is for an analyzer that uses a wavelength dispersion-type X-ray spectrometer. This analyzer stores standard sensitivity data including a relationship between the wavelength and the intensity of a characteristic X‐ray generated from a standard sample. This correction method comprises: a step for acquiring actual measurement data indicating the result of actually measuring wavelengths and intensities for two or more different characteristic X‐rays in the standard sample; and a step for calculating an intensity ratio (C3) of an intensity with respect to a prescribed wavelength in the actual measurement data to an intensity with respect to a corresponding wavelength in the standard sensitivity data, and for correcting the standard sensitivity data on the basis of the intensity ratio (C3).

Description

[Technical Field]

[0001] The present invention relates to a correction method, an analytical device, and a program, and more particularly to an analytical device having a wavelength dispersive X-ray spectrometer, a correction method therefor, and a program therefor. [Background technology]

[0002] An electron probe micro analyzer (EPMA) is known as an analytical device that uses a wavelength dispersive X-ray spectrometer (WDS). In an EPMA, characteristic X-rays generated by irradiating a sample with an electron beam are dispersed using a plurality of dispersing crystals with different spectral wavelength ranges. The wavelengths and intensities of the dispersed characteristic X-rays are then detected using a detector. Japanese Patent Laid-Open Publication No. 2010-190810 (Patent Document 1) discloses an EPMA that performs qualitative or quantitative analysis of elements contained in a sample based on the wavelengths and X-ray intensities obtained in this manner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-190810 Summary of the Invention [Problem to be solved by the invention]

[0004] One representative example of such EPMA is one that stores standard sensitivity data, which includes the relationship between the wavelength and intensity of characteristic X-rays obtained by measuring a standard sample whose contained elements and their concentrations are known. By comparing the sensitivity data obtained by measuring an actual sample with the standard sensitivity data, the concentration of the elements contained in the sample can be easily determined.

[0005] However, in reality, it is known that the sensitivity to the characteristic X-rays generated from a standard sample varies from instrument to instrument due to individual differences in the analyzing crystal, detector, etc. Therefore, as mentioned above, when measuring a sample based on the standard sensitivity data, there is a possibility that errors will occur in the measurement results.

[0006] The present disclosure has been made in consideration of the above circumstances, and its purpose is to improve the accuracy of measurements in an analytical device that uses a wavelength dispersive X-ray spectrometer by reducing the influence of individual differences. [Means for solving the problem]

[0007] A first aspect of the present disclosure is a correction method for an analytical instrument using a wavelength-dispersive X-ray spectrometer. The analytical instrument stores standard sensitivity data including a relationship between the wavelength and intensity of characteristic X-rays generated from a standard sample. The correction method includes the steps of acquiring measured data resulting from measuring the wavelength and intensity of two or more different characteristic X-rays in the standard sample, calculating an intensity ratio between the intensity for a specific wavelength in the measured data and the intensity for the corresponding wavelength in the standard sensitivity data, and correcting the standard sensitivity data based on the intensity ratio. [Effects of the Invention]

[0008] According to the correction method disclosed herein, standard sensitivity data can be corrected based on actual measurement data obtained by measuring a standard sample using an analytical device. This makes it possible to obtain standard sensitivity data that reflects individual differences between analytical devices. This improves the accuracy of measurements using the standard sensitivity data in the analytical device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a configuration of an analyzer according to an embodiment of the present invention. [Figure 2] FIG. 2 illustrates an example of a hardware configuration of a computer. [Figure 3] FIG. 10 is a diagram showing an example of a default standard sensitivity screen. [Figure 4]FIG. 10 is a diagram showing an example of an actual measurement data acquisition screen. [Figure 5] FIG. 10 is a diagram illustrating an example of a correction coefficient setting screen. [Figure 6] FIG. 10 is a diagram illustrating an example of a correction confirmation screen. [Figure 7] FIG. 10 is a diagram showing an example of a standard sensitivity screen after correction. [Figure 8] 10 is a flowchart illustrating a process related to correction of standard sensitivity data. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0011] [1. Configuration of the analytical device] 1 is a schematic diagram showing the configuration of an analytical apparatus 100 according to an embodiment of the present invention. Analytical apparatus 100 according to the present embodiment is an X-ray analytical apparatus that measures and analyzes a sample using WDS. Analytical apparatus 100 is, for example, an EPMA.

[0012] Referring to FIG. 1, an analysis device 100 according to this embodiment includes a computer 1, an irradiation unit 5, a display 16, and an input unit 17.

[0013] The computer 1 controls the analysis device 100 . The irradiation unit 5 includes an electron gun 52, a deflection coil 53, an objective lens 54, a sample stage 57, a sample stage drive unit 50, a WDS 6, a deflection coil control unit 51, a secondary electron detection unit 55, and a backscattered 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 backscattered electron detection unit 56 are provided in an irradiation chamber 59. During analysis of the sample S, the inside of the irradiation chamber 59 is evacuated to a near-vacuum state.

[0014] The electron gun 52 is an excitation source that generates an electron beam E. The electron beam E corresponds to one example of a "charged particle beam." The electron beam E is irradiated onto an irradiation position of a sample S on a sample stage 57. A converging lens (not shown) adjusts the beam of the electron beam E. The deflection coil 53 forms a magnetic field using a driving current supplied from a deflection coil control unit 51. The magnetic field formed by the deflection coil 53 deflects the electron beam E. The objective lens 54 is provided between the deflection coil 53 and the sample S placed on the sample stage 57. The objective lens 54 focuses the electron beam E that has passed through the deflection coil 53.

[0015] 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 within a horizontal plane.

[0016] In the irradiation unit 5, the irradiation position of the electron beam E on the sample S can be scanned two-dimensionally 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 narrow, scanning is performed by the deflection coil 53. When the scanning range is relatively wide, scanning is performed by moving the sample stage 57.

[0017] The WDS 6 is a wavelength dispersive X-ray spectrometer for detecting a detection signal of characteristic X-rays emitted from the irradiation position of the sample S.

[0018] Although only one WDS 6 is shown in FIG. 1, in reality, multiple WDSs 6 are provided in the irradiation unit 5 so as to surround the sample S. Each WDS 6 has an analyzing crystal with a different spectral wavelength range. The configuration of each WDS 6 is the same except for the analyzing crystal.

[0019] The WDS 6 includes an analyzing crystal 61, a detector 62, and a slit 63. The irradiation position of the electron beam E on the sample S, the analyzing crystal 61, and the detector 62 are arranged on a Rowland circle (not shown).

[0020] The analyzing crystal 61 diffracts characteristic X-rays emitted from the irradiation position of the sample S. The analyzing crystal 61 is one of crystals having different spectral wavelength ranges, made of, for example, lithium fluoride (LIF), pentaerythritol (PET), rubidium phthalate (RAP), etc. The analyzing crystal 61 is tilted while moving along a straight line 64 by a driving mechanism (not shown).

[0021] The detector 62 is an X-ray detector that detects the characteristic X-rays diffracted by the analyzing crystal 61. The detector 62 rotates as shown in the figure in response to the movement of the analyzing crystal 61 by a drive mechanism (not shown) so that the incident angle of the characteristic X-rays with respect to the analyzing crystal 61 and the exit angle of the diffracted X-rays satisfy the Bragg diffraction condition. This allows wavelength scanning of the characteristic X-rays emitted from the sample S. The characteristic X-rays are detected and amplified by the detector 62 and sent as a pulsed signal from the WDS 6 to the computer 1. The intensity of the characteristic X-rays is measured in the computer 1 as a pulse signal measured per unit time, and is usually expressed in units of cps. Note that the configuration of each WDS is not limited to the above configuration, and various conventionally known configurations can be used.

[0022] The secondary electron detector 55 detects a detection signal of secondary electrons emitted from the irradiation position of the sample S. The detection signal of the secondary electron detector 55 is sent to the computer 1.

[0023] The backscattered electron detector 56 detects a detection signal of backscattered electrons emitted from the irradiation position of the sample S. The detection signal of the backscattered electron detector 56 is sent to the computer 1.

[0024] The deflection coil control unit 51 controls the drive current supplied to the deflection coil 53 in accordance with instructions from the computer 1. The deflection coil control unit 51 controls the drive current in accordance with a predetermined drive current pattern (magnitude and change speed). This allows the irradiation position of the electron beam E on the sample S to be scanned at a desired scan speed.

[0025] The computer 1 is communicably connected to the irradiation unit 5. The computer 1 generates control signals for controlling the operation of each part of the irradiation unit 5 according to a built-in program and table. The computer 1 outputs the generated control signals to the irradiation unit 5.

[0026] Furthermore, 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 an SEM image, which is a secondary electron image of the irradiation position on the sample S, based on a detection signal of the secondary electrons detected by the secondary electron detector 55. Furthermore, the computer 1 generates a backscattered electron image of the irradiation position on the sample S based on a detection signal of the backscattered electrons detected by the backscattered electron detector 56.

[0027] The computer 1 further generates a distribution image (X-ray image) of the analysis target element at the irradiation position of the sample S based on the detection signals of the characteristic X-rays detected by the four WDSs. Furthermore, the computer 1 receives a wavelength scan of the X-rays at the irradiation position. The computer 1 generates an X-ray spectrum based on the received wavelength scan of the X-rays. The computer 1 performs qualitative analysis and / or quantitative analysis based on the X-ray spectrum.

[0028] 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 in response to commands from the computer 1. The display 16 also displays reference images that the user refers to in order to control the irradiation position of the charged particle beam in response to commands from the computer 1. The reference images include at least one of an X-ray image, an SEM image, and a backscattered electron image. The display 16 may also be configured to display processing information related to the analysis of backscattered electrons, secondary electrons, and characteristic X-rays. In such a configuration, for example, the display 16 displays an X-ray spectrum and the results of qualitative and quantitative analysis based thereon.

[0029] Therefore, the user can give various instructions to the computer 1 for controlling the irradiation unit 5 based on the display on the display 16. Furthermore, the user can use the computer 1 to analyze data detected by the irradiation unit 5 based on the display on the display 16. That is, the user can use the display on the display 16 to view, for example, numerical values ​​indicating the observation conditions, observed images (e.g., X-ray images, SEM images, backscattered electron images), and graphs showing the analysis results of the obtained characteristic X-rays, secondary electrons, and backscattered electrons.

[0030] The input unit 17 is connected to the computer 1 and is configured to be able to communicate with the computer 1. The input unit 17 is used to input user commands 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.

[0031] As described above, the analysis device 100 is configured to irradiate the surface of the sample S with an electron beam and detect signals emitted from the surface of the sample S. The detected signals include characteristic X-rays having wavelengths specific to elements contained on the surface of the sample S, backscattered electrons, and secondary electrons. The analysis device 100 can identify and quantify elements present at an analysis position on the surface of the sample S by analyzing the wavelength and intensity of the detected characteristic X-rays.

[0032] Furthermore, the analysis device 100 can observe the shape and composition of the surface of the sample S using the detected secondary electrons and backscattered electrons. The user can search for a target portion to be analyzed on the surface of the sample S while observing the SEM image or backscattered electron image of the irradiation position. Specifically, the user determines the target portion while observing the electron image when the irradiation position has determined that it contains the target portion to be analyzed. The user then performs qualitative and quantitative analysis of the target portion on the surface of the sample S.

[0033] [2. Hardware configuration] 2 is a diagram showing an example of a hardware configuration of computer 1. Referring to FIG. 2, 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.

[0034] The processor 10 is realized by, for example, at least one CPU (Central Processing Unit). The processor 10 controls the analysis device 100 in accordance with a program stored in a memory 11.

[0035] The memory 11 is realized by a storage device such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk Drive). The ROM can store programs executed by the processor 10. The RAM can temporarily store data used during execution of a program by the processor 10 and can function as a temporary data memory used as a work area. The HDD is a non-volatile storage device. In addition to or instead of the HDD, a semiconductor storage device such as a flash memory may be used. The programs and / or data may be stored in an external storage device accessible by the processor 10.

[0036] The communication interface 15 is an interface for the computer 1 to communicate with external devices wirelessly or via a wire. The I / O interface 13 is an interface for input to or output from the computer 1. As shown in FIG. 2 , the I / O interface 13 is connected to the display 16, the input unit 17, and the irradiation unit 5.

[0037] The display 16 is realized by a display device. The input unit 17 is realized by an input device that accepts input from a user. The input unit 17 is, for example, a keyboard, a mouse, and / or a touch panel that is integrated with the display screen of the display 16.

[0038] Computer 1 does not have to be configured by a single computer, but may be configured by multiple computers. That is, the processing performed by computer 1 may be distributed and performed by multiple computers. For example, computer 1 may be configured by a control computer that controls irradiation unit 5 and an analysis computer that analyzes the detection signal of X-rays detected by irradiation unit 5. In this case, the control computer and the analysis computer may each be equipped with an input unit and a display.

[0039] [3. Comparison with conventional analytical equipment] In an EPMA using conventional WDS, it is possible to obtain data including the wavelength and intensity of characteristic X-rays emitted from a standard sample (hereinafter also referred to as "standard sensitivity data") by irradiating an electron beam onto a standard sample whose contained elements and their concentrations are known. Some EPMAs are sold with sensitivity data obtained by measuring a standard sample in a representative device stored as initial standard sensitivity data, and standard sensitivity curves approximated based on this data are stored.

[0040] This will be explained in more detail below. The intensity of characteristic X-rays is proportional to the concentration of the element that generates them and the current value of the irradiating electron beam. Therefore, if a standard sample containing known elements and their concentrations is irradiated with an electron beam of known current and the intensity of the characteristic X-rays is measured, the proportional relationship described above makes it possible to determine the characteristic X-ray intensity value measured when the concentration of the target element is 100%, expressed as the intensity value per unit current of the irradiating electron beam, i.e., the standard sensitivity value. The standard sensitivity value is expressed, for example, as the intensity value per 1 A (ampere) of irradiation current, and its unit is cps / A.

[0041] Multiplying the standard sensitivity value by the probe current value during measurement makes it possible to determine the intensity value that can be measured under those probe current conditions when the concentration of the target element is 100%, i.e., the 100% intensity value. Dividing the actually measured intensity value by this 100% intensity value makes it possible to easily determine the concentration of the target element.

[0042] Typically, there are multiple characteristic X-rays within the spectral wavelength range of a single analyzing crystal. Characteristic X-rays are classified into the Kα series, Lα series, Mα series, etc. depending on the atomic nucleus that contributes to the generation of X-rays. However, within the same series, the wavelengths of characteristic X-rays are arranged in order of atomic number, and it is known that the standard sensitivity value shows a curved change with respect to the wavelength value (see Figure 3: Default Standard Sensitivity Screen).

[0043] Using these characteristics, it is possible to curve-fit the change in standard sensitivity value versus wavelength from a data set created by determining the wavelength and standard sensitivity value for each characteristic X-ray for each individual analyzing crystal and even for each X-ray series, i.e., standard sensitivity data. The curve obtained in this way is called a standard sensitivity curve. Because the standard sensitivity value can be calculated from the wavelength value using the approximation formula given to the standard sensitivity curve, standard sensitivity values ​​can be given even for characteristic X-rays for which standard sensitivity values ​​cannot be measured due to reasons such as the difficulty of obtaining standard samples, and the intensity of the measured characteristic X-ray can be converted into a concentration value.

[0044] In an EPMA using a conventional WDS, the initial standard sensitivity data is data obtained by measuring the sensitivity of characteristic X-rays in each WDS of a representative device, for example, at a company that sells EPMAs. The vendor measures the intensities of as many characteristic X-rays as possible using many types of standard samples, and the initial standard sensitivity data and standard sensitivity curve are set to accurately reflect the sensitivity of each WDS in the representative device.

[0045] In an EPMA that stores the standard sensitivity data and standard sensitivity curves set in this way, the wavelength and intensity of the characteristic X-rays obtained by measuring a sample with each instrument can be compared with the standard sensitivity values ​​obtained from the standard sensitivity curve, making it possible to determine the elements contained in the sample and their concentrations.

[0046] However, in reality, the "sensitivity" of characteristic X-rays, i.e., the "intensity of X-rays obtained when a specified standard sample is measured under the same conditions," differs from instrument to instrument due to individual differences in the analyzing crystal, detector, and other mechanisms included in the WDS. Therefore, as mentioned above, measurement results obtained by comparing the wavelength and intensity of characteristic X-rays obtained by measuring a sample with an individual instrument with the initial standard sensitivity value may contain errors.

[0047] Therefore, it is desirable to correct the initial standard sensitivity data and standard sensitivity curve for each individual instrument to standard sensitivity data and standard sensitivity curve that reflect the sensitivity of that individual instrument. However, because the types of standard samples that users can prepare are limited, it is extremely difficult to remeasure all of the characteristic X-ray sensitivities measured by the manufacturer for each individual instrument. In addition, although instruments usually have the function to update the standard sensitivity data and standard sensitivity curve, if a user changes only part of the standard sensitivity data to the extent possible using their own standard samples, the resulting standard sensitivity curve may be unnaturally distorted, which may actually reduce the accuracy and validity of the standard sensitivity curve.

[0048] Therefore, in this embodiment, an analytical device 100 is provided that uses initial standard sensitivity data as default standard sensitivity data, corrects the default standard sensitivity data based on sensitivity data obtained by actually measuring a relatively small number of standard samples, and uses the results to create a standard sensitivity curve. This allows users to use a standard sensitivity curve that is tailored to the characteristics of their individual device. This reduces the impact of individual device differences on measurement results, improving the accuracy of measurement for each device.

[0049] [4. Correction method for standard sensitivity data] Next, a method for correcting the default standard sensitivity data will be described using display screens (FIGS. 3 to 7) displayed on the display 16 by the processor 10. The user corrects the standard sensitivity data by referring to the display screens.

[0050] In this specification, correction of the standard sensitivity data of a WDS having a PET dispersing crystal will be described as an example of the standard sensitivity data of each WDS. The standard sensitivity data of WDSs having other dispersing crystals can also be corrected in the same way.

[0051] (4-1. Default standard sensitivity screen) FIG. 3 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 to display the standard sensitivity screen into the analytical device 100. In one implementation example, an operation screen (not shown) of the analytical device 100 displayed on the display 16 of the computer 1 includes a button for displaying the standard sensitivity screen. When the user selects the button, the standard sensitivity screen is displayed on the display 16. The selection is made, for example, by clicking using the input unit 17.

[0052] 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, i.e., standard sensitivity data and its graph, a sensitivity graph. The sensitivity graph of the Kα series, the sensitivity graph of the Lα series, and the sensitivity graph of the Mα series will hereinafter also be referred to as the "Kα graph," the "Lα graph," and the "Mα graph," respectively.

[0053] In each sensitivity graph, the horizontal axis represents the spectral wavelength (Å) and the vertical axis represents the intensity (cps / A) of characteristic X-rays. In each sensitivity graph, black circles such as those indicated by C1 represent default standard sensitivity data. In each sensitivity graph, the standard sensitivity data exhibits a curved change. In the example of FIG. 3, each sensitivity graph includes a standard sensitivity curve such as that indicated by the dashed line L1. The standard sensitivity curve is a curve obtained by polynomial approximation of the standard sensitivity data. In the example of FIG. 3, the standard sensitivity curve is a cubic curve that best fits the standard sensitivity data. In this specification, the "best fitting curve" refers, for example, to the curve that has the smallest error from the original data. The error from the original data is determined, for example, by the least squares method.

[0054] By referring to the standard sensitivity screen, the user can check the standard sensitivity data currently used in the instrument. The standard sensitivity data can be corrected based on actual measurement data. In this specification, "actual measurement data" refers to sensitivity data obtained by actually measuring a standard sample using an instrument owned by the user.

[0055] (4-2. Measurement data acquisition screen) 4 is a diagram showing an example of an actual measurement data acquisition screen. The actual measurement data acquisition screen is a screen for acquiring actual measurement data. The actual measurement data acquisition screen is displayed when a user inputs an instruction to correct the standard sensitivity curve into the analytical device 100. In one implementation example, an operation screen (not shown) of the analytical device 100 displayed on the display 16 of the computer 1 includes a button for executing correction of the standard sensitivity curve. When the user selects the button, the actual measurement data acquisition screen is displayed on the display 16.

[0056] The measurement data acquisition screen includes a table T2 and a button B1. The rows of table T2 show the sensitivity data for the Kα series, Lα series, and Mα series, respectively. Table T2 includes a sensitivity graph in the left column and a sensitivity table, which is a table of sensitivity data, in the right column.

[0057] The sensitivity tables for the Kα series, Lα series, and Mα series are also called the Kα table, Lα table, and Mα table, respectively. Each sensitivity table includes the following items: "characteristic X-rays," "wavelength (Å)," "standard intensity (cps / A)," "measured intensity (cps / A)," and "intensity ratio."

[0058] The "Characteristic X-rays" section shows the name of each characteristic X-ray. The name of the characteristic X-ray is indicated by the element symbol and series. For example, the characteristic X-ray of the Kα series of silicon (element symbol Si) is indicated as "SiKα."

[0059] The item "Wavelength (Å)" indicates the wavelength specific to the characteristic X-ray. The item "Standard intensity (cps / A)" indicates the intensity of the characteristic X-rays corresponding to the wavelength in the standard sensitivity data (hereinafter also referred to as "standard intensity").

[0060] The item "Measured intensity (cps / A)" indicates the intensity of the characteristic X-rays corresponding to the wavelength in the measured data (hereinafter also referred to as "measured intensity").

[0061] The item "Intensity Ratio" indicates the ratio between the measured intensity and the standard intensity. In one implementation, the intensity ratio is the measured intensity divided by the standard intensity.

[0062] In one implementation example, the values ​​of the items "characteristic X-rays," "wavelength (Å)," and "standard intensity (cps / A)" are displayed in advance based on standard sensitivity data stored in 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)" and the value of the item "standard intensity (cps / A)" on the same line when the value of the item "standard intensity (cps / A)" on the same line is input.

[0063] In each sensitivity graph, the horizontal axis indicates the spectral wavelength (Å) and the vertical axis indicates the characteristic X-ray intensity (cps / A). In each sensitivity graph, black circles such as those shown in C1 indicate the default standard sensitivity data. In each sensitivity graph, white circles such as those shown in C2 indicate the actually measured data.

[0064] In one implementation example, the black circle indicating standard sensitivity data as shown in C1 is displayed in advance based on the standard sensitivity data stored in the memory 11. The white circle indicating actual measurement data as shown in C2 is configured to be automatically displayed when the value of the "Actual Measurement Intensity (cps / A)" item in the sensitivity table is entered.

[0065] Button B1 is a button used to complete the acquisition of actual measurement data. When selected, button B1 is configured to display a correction coefficient setting screen shown in FIG.

[0066] The measurement data acquisition screen is used, for example, as follows: The user inputs the measured intensity into a cell of the item "Measured Intensity (cps / A)." This input is performed by the user inputting the measured intensity based on the measured data of a standard sample stored in memory 11. Specifically, for example, the user refers to the measured data and inputs the measured intensity using input unit 17. Furthermore, for example, when the user selects a 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 may be automatically input.

[0067] When the user inputs the intensity corresponding to the "Measured Intensity (cps / A)" cell, the "Intensity Ratio" value in the same row is automatically calculated. Also, a white circle corresponding to the "Measured Intensity (cps / A)" is displayed on the sensitivity graph, as shown in C2.

[0068] As described above, the actual measurement data can be acquired using the actual measurement data acquisition screen. Furthermore, the user can intuitively compare the input actual measurement intensity with the standard intensity by referring to the sensitivity graph.

[0069] When the user selects button B1 to complete the acquisition of actual measurement data, the correction coefficient setting screen shown in FIG. 5 is displayed.

[0070] (4-3. Correction coefficient setting screen) 5 is a diagram showing an example of a correction coefficient setting screen. The correction coefficient setting screen is a screen for setting a correction coefficient. The correction coefficient setting screen includes a table T3 and a button B2. Table T3 includes a graph (intensity ratio graph) in the left column and a table (intensity ratio table) in the right column for intensity ratio data.

[0071] The intensity ratio table includes the items "characteristic X-rays," "wavelength (Å)," and "intensity ratio." The items "characteristic X-rays," "wavelength (Å)," and "intensity ratio" are the same as the corresponding items in the sensitivity table in Figure 4 ("characteristic X-rays," "wavelength (Å)," and "intensity ratio"). The values ​​corresponding to the items "characteristic X-rays," "wavelength (Å)," and "intensity ratio" in the intensity ratio table are entered as the values ​​of the corresponding items ("characteristic X-rays," "wavelength (Å)," and "intensity ratio") in the row in the sensitivity table in Figure 4 where "measured intensity (cps / A)" is entered. In other words, for characteristic X-rays for which measured intensities have been obtained in the sensitivity table in Figure 4, the name, wavelength, and intensity ratio of that characteristic X-ray are automatically entered in the intensity ratio table in Figure 5.

[0072] 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, black circles such as those shown in C3 indicate the relationship between wavelength and intensity ratio in the intensity ratio table, and are automatically displayed based on the intensity ratio table.

[0073] The dashed line L2 on the intensity ratio graph is a graph obtained by polynomial approximation of the intensity ratio (black dots) versus wavelength, as shown in C3. This polynomial approximation is performed automatically by the processor 10 based on the relationship between wavelength and intensity ratio. More specifically, the coefficients of each term in the polynomial are determined, for example, using the least squares method, so as to minimize the error from the intensity ratio data. In the example of FIG. 5, the dashed line L2 displays the results of fitting four data points by the processor 10 using a cubic equation. In this specification, this polynomial-approximated value is referred to as a correction coefficient and is used to correct the standard sensitivity data. This configuration allows correction coefficients to be set even for wavelengths for which corresponding actual measurement data has not been acquired. The line indicating the correction coefficient, shown by the dashed line L2 on the intensity ratio graph, is hereinafter also referred to as the "correction coefficient line."

[0074] Button B2 is a button used to complete the setting of the correction coefficient and to confirm the results of the correction performed using the set correction coefficient. When button B2 is selected, it is configured to display a correction confirmation screen shown in FIG.

[0075] As described above, the correction coefficients are set on the correction coefficient setting screen. By referring to the intensity ratio graph, the user can intuitively understand the intensity ratio or correction coefficient value for each wavelength. Furthermore, the user can confirm that the correction coefficient line is properly fitted to the intensity ratio.

[0076] When the user selects button B2 to complete the setting of the correction coefficient, the correction confirmation screen shown in FIG. 6 is displayed.

[0077] (4-4. Correction confirmation screen) Fig. 6 is a diagram showing an example of a correction confirmation screen. The correction confirmation screen is a screen for the user to confirm the correction of the standard sensitivity data using the correction coefficient set in Fig. 5. The correction confirmation screen includes a table T4 and a button B3.

[0078] In Table T4, each row contains a sensitivity graph for the Kα series, Lα series, and Mα series. In each sensitivity graph, the horizontal axis indicates the spectral wavelength (Å) and the vertical axis indicates the characteristic X-ray intensity (cps / A). In each sensitivity graph, the black circle indicated by C1 represents the default standard sensitivity data. In each sensitivity graph, the white circle indicated by C4 represents the standard sensitivity data after correction based on the correction coefficient set in Figure 5.

[0079] Button B3 is a button used to determine the correction of the standard sensitivity data. When selected, button B3 determines the correction of the standard sensitivity data and displays the corrected standard sensitivity screen shown in FIG. 7.

[0080] (4-5. Standard sensitivity screen after correction) 7 is a diagram showing an example of a standard sensitivity screen after correction. The standard sensitivity screen after correction includes Table T5. In Table T5, each row includes a sensitivity graph for each of the Kα series, Lα series, and Mα series.

[0081] In each sensitivity graph, the horizontal axis represents the spectral wavelength (Å) and the vertical axis represents the intensity of characteristic X-rays (cps / A). In each sensitivity graph, the corrected standard sensitivity data, as indicated by C4, exhibits a curved change. In the example of Figure 7, each sensitivity graph includes a corrected standard sensitivity curve, as indicated by the dashed line L3. The corrected standard sensitivity curve is a curve obtained by polynomial approximation of the corrected standard sensitivity data. In the example of Figure 7, the standard sensitivity curve is a cubic curve that best fits the standard sensitivity data.

[0082] The standard sensitivity curve is automatically calculated by the processor 10 based on the standard sensitivity data. With this configuration, intensities for wavelengths for which there are no data points for the standard sensitivity data are also interpolated. Therefore, even if a user measures a sample and detects characteristic X-rays at a wavelength for which there are no corresponding data points for the standard sensitivity data, the concentration of the corresponding element can be calculated using the standard sensitivity curve.

[0083] After the correction of the standard sensitivity data is completed as shown in Fig. 6, when the user inputs an instruction to display the standard sensitivity screen into the analytical device 100, the standard sensitivity screen of Fig. 7 is displayed instead of the standard sensitivity screen of Fig. 3. In this way, the user can check the current standard sensitivity data by referring to the standard sensitivity screen.

[0084] [5. Correction Control] Fig. 8 is a flowchart illustrating processing related to correction of standard sensitivity data, which is executed by computer 1. Referring to Fig. 8, in step (hereinafter also referred to as ST) 02, processor 10 uses the actual measurement data acquisition screen (Fig. 4) to acquire actual measurement data of a standard sample that has been measured using an apparatus owned by the user.

[0085] In ST04, the processor 10 calculates the intensity ratio, which is the ratio between the intensity at a specific wavelength in the actual measurement data and the intensity at the corresponding wavelength in the standard sensitivity data. The calculated intensity ratio is displayed as a value corresponding to the item "intensity ratio" in the sensitivity table of FIG. 4 and the intensity table of FIG. 5.

[0086] In ST06, the processor 10 performs polynomial approximation on the intensity ratio with respect to wavelength. The result of the polynomial approximation is displayed as a correction coefficient line (dashed line L2) on the intensity graph in FIG.

[0087] In ST08, the processor 10 sets the polynomial-approximated value as the correction coefficient. In ST10, the processor 10 corrects the default standard sensitivity data based on the set correction coefficients. The corrected standard sensitivity data is displayed in the sensitivity graphs of FIGS.

[0088] In ST12, the processor 10 sets a standard sensitivity curve by polynomial approximating the corrected standard sensitivity data. The set standard sensitivity curve is displayed on the sensitivity graph of Fig. 6. After completing ST12, the processor 10 ends the process.

[0089] The process shown in Figure 8 allows the standard sensitivity data to be corrected based on actual measurement data obtained by measuring a standard sample using a user's own instrument. This makes it possible to obtain standard sensitivity data that reflects individual differences between instruments. This improves the accuracy of measurements using the standard sensitivity data in analytical instruments.

[0090] [6. Supplementary Notes] (6-1. Polynomial approximation of correction coefficients) As shown in ST06 to ST08 in Fig. 8, the analysis device 100 sets the correction coefficients by polynomial approximating the intensity ratio with respect to wavelength. To polynomially approximate the intensity ratio, it is necessary to obtain measured data in ST04, which is the result of actually measuring the wavelength and intensity of two or more different characteristic X-rays. "Two or more different characteristic X-rays" refers to characteristic X-rays having two or more different intrinsic wavelengths.

[0091] The inventors also found that in this polynomial approximation, a cubic curve best fits the measured data. In other words, when the correction coefficient is a cubic expression, the error (e.g., mean square error) with the measured data is small. Thus, to properly fit with a cubic curve, the measured data must include at least four data points. Therefore, preferably, in ST04, the processor 10 acquires measured data that is the result of actually measuring the wavelengths and intensities of four or more different characteristic X-rays. In ST06, the processor 10 also approximates the intensity ratio with respect to wavelength to a cubic expression.

[0092] However, the step of setting the correction coefficients based on the intensity ratios for wavelengths shown in ST06 to ST08 is not necessarily limited to the polynomial approximation described above. For example, the correction coefficients may be set by linearly interpolating between the data points of the intensity ratios. In this case, the correction coefficient line is a line graph that linearly connects each data point. However, the method of using polynomial approximation is superior for setting the correction coefficients.

[0093] For example, in a method of linearly interpolating the intensity ratio, if the intensity ratio data contains even one extremely large or small outlier due to some factor, such as a measurement failure of the actual intensity, the correction coefficient line near the outlier will also show extreme changes. Therefore, the standard sensitivity data corrected using the correction coefficient line will no longer have a smooth curve, which could lead to measurement errors. On the other hand, when setting correction coefficients using polynomial approximation of the intensity ratio, even if a single outlier occurs in the intensity ratio data, the correction coefficient line can be set smoothly due to the influence of other points, even if it is near the outlier. Therefore, the standard sensitivity data corrected using the correction coefficient line will also have a smooth curve, reducing the possibility of measurement errors.

[0094] Furthermore, the polynomial approximation method allows for relatively appropriate correction of standard sensitivity data based on actual measurement data of standard samples, compared to other methods that use line graphs, etc. Furthermore, even if approximately 20 types of standard samples are used with an EPMA, two to seven types of characteristic X-rays can be measured for each analyzing crystal, so the standard sensitivity data can be corrected even within this range, which is an advantage. Therefore, users do not need to obtain new standard samples to correct the standard sensitivity data, and correction can be easily performed.

[0095] (6-2. How to obtain actual measurement data) Furthermore, the method of acquiring the measured data is not limited to the above example. For example, if the user inputs the values ​​of the measured data for the intrinsic wavelength of the characteristic X-ray, the standard sensitivity data may be corrected automatically without any subsequent calculations being displayed on the display 16. That is, the processes for correcting the standard sensitivity data described on the screens of Figures 5 to 8 may all be performed in the background. However, the display of the screens of Figures 5 to 8 has the advantage of allowing the user to visually confirm that the standard sensitivity data has been properly corrected.

[0096] Furthermore, when a user inputs an instruction to correct the standard sensitivity data into the analytical device 100, the analytical device 100 displays an instruction for the standard sample to be placed in the analytical device 100, and once the user places the standard sample, the analytical device 100 can automatically acquire the actual measurement data and correct the standard sensitivity data.

[0097] (6-3. Timing of correction) The standard sensitivity data is corrected, for example, after a user purchases the instrument and before measuring a sample to be measured. This reduces the influence of individual differences between instruments and improves the accuracy of the measurement before measuring the sample.

[0098] Furthermore, it is known that repeated measurements in analytical instruments including WDS can cause deterioration in the sensitivity of the instrument over time. To reduce the effects of this deterioration over time, the standard sensitivity data may be corrected periodically (for example, once a year). In this case, the correction may be performed on the default standard sensitivity data, or on the standard sensitivity data corrected immediately before the correction.

[0099] (6-4. Correction of standard sensitivity data based on standard sensitivity curve) Furthermore, the correction of the standard sensitivity data does not necessarily have to be a correction of the data points contained in the standard sensitivity data as described above, but may be, for example, a correction of the standard sensitivity curve.

[0100] Correction of the standard sensitivity curve is performed, for example, as follows. First, the ratio between the measured intensity of the characteristic X-ray and the value of the standard sensitivity curve for the corresponding wavelength is calculated as an intensity ratio. Next, a correction coefficient is calculated based on the intensity ratio. Then, the product of the correction coefficient and the value of the standard sensitivity curve before correction is recorded as the corrected standard sensitivity curve.

[0101] With this configuration, it is possible to correct the standard sensitivity curve even if, for example, characteristic X-rays actually measured in a user's device are not included in the data points of the default standard sensitivity data. Also, for example, it is possible to correct the standard sensitivity curve even in a device that includes, as the default standard sensitivity data, only a standard sensitivity curve obtained by polynomial approximation of data points actually measured in a representative device, instead of the data points.

[0102] [Aspect] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0103] (Item 1) A correction method according to one aspect is a correction method for an analytical instrument using a wavelength-dispersive X-ray spectrometer. The analytical instrument stores standard sensitivity data including the relationship between the wavelength and intensity of characteristic X-rays generated from a standard sample. The correction method includes the steps of acquiring measured data that is the result of measuring the wavelength and intensity of two or more different characteristic X-rays in the standard sample, calculating an intensity ratio that is the ratio between the intensity for a specific wavelength in the measured data and the intensity for the corresponding wavelength in the standard sensitivity data, and correcting the standard sensitivity data based on the intensity ratio.

[0104] According to the correction method described in paragraph 1, the standard sensitivity data can be corrected based on the actual measurement data obtained by measuring a standard sample using an analytical device. Therefore, it is possible to obtain standard sensitivity data that reflects the individual differences in sensitivity of analytical devices. Therefore, it is possible to improve the accuracy of measurements using the standard sensitivity data in the analytical device.

[0105] (2) In the correction method described in (1), the correction step includes a step of setting a correction coefficient based on the intensity ratio, and a step of storing the product of the correction coefficient and the standard sensitivity data before correction as the standard sensitivity data after correction.

[0106] According to the correction method described in paragraph 2, a correction coefficient that reflects the intensity ratio, i.e., the ratio of sensitivities depending on the device, can be reflected in the standard sensitivity data. Therefore, standard sensitivity data that reflects the sensitivity ratio depending on the device can be obtained. Therefore, the accuracy of measurements using the standard sensitivity data in an analytical device can be improved.

[0107] (Item 3) In the correction method described in item 2, the setting step includes a step of polynomial approximating the intensity ratio to wavelength in the actual measurement data, and a step of setting the polynomial-approximated value as the correction coefficient.

[0108] According to the correction method described in paragraph 3, correction coefficients can be set even for wavelengths for which no corresponding measured data has been obtained. Furthermore, when a correction coefficient is set for a wavelength for which no corresponding measured data has been obtained using polynomial approximation, a correction coefficient line can be set as a smooth curve even if the measured data contains outliers. Therefore, correcting the standard sensitivity data using a correction coefficient line based on polynomial approximation reduces the possibility of measurement errors compared to correcting the standard sensitivity data using a correction coefficient line that linearly interpolates the intensity ratio, for example.

[0109] (Item 4) In the correction method described in Item 3, the acquiring step includes a step of acquiring measured data that is the result of actually measuring the wavelength and intensity for four or more different characteristic X-rays, and the polynomial approximating step includes a step of approximating the intensity ratio to the wavelength to a cubic equation.

[0110] The inventors discovered that in polynomial approximation of intensity ratios, a cubic curve best fits the measured data. Therefore, the correction method described in Section 4 can obtain a correction coefficient line that best fits the measured data. In other words, it is possible to set a correction coefficient that appropriately reflects the sensitivity of the analytical device. By correcting the standard sensitivity data using such a correction coefficient, the accuracy of measurements using the standard sensitivity data can be improved.

[0111] (Item 5) In the correction method described in any one of Items 2 to 4, the correction step includes a step of setting a standard sensitivity curve by polynomial approximation of the corrected standard sensitivity data, and the standard sensitivity curve is used in an analytical device to calculate the concentration of an element contained in the sample based on the intensity of characteristic X-rays emitted from the sample to be measured.

[0112] According to the correction method described in paragraph 5, the intensity for wavelengths for which there are no data points in the standard sensitivity data is also interpolated. Therefore, even if a user measures a sample and detects characteristic X-rays at a wavelength for which there are no corresponding data points in the standard sensitivity data, the concentration of the corresponding element can be calculated using the standard sensitivity curve.

[0113] (Item 6) An analytical device according to another aspect is an analytical device that uses a wavelength dispersive X-ray spectrometer and includes a memory that stores standard sensitivity data and actual measurement data, and a processor that executes the correction method described in any one of items 1 to 5.

[0114] (7th paragraph) A program according to still another aspect causes a computer to execute the correction method according to any one of the first to sixth paragraphs.

[0115] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0116] 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 stage drive unit, 51 Deflection coil control unit, 52 Electron gun, 53 Deflection coil, 54 Objective lens, 55 Secondary electron detection unit, 56 Backscattered electron detection unit, 57 Sample stage, 61 Analyzing crystal, 62 Detector, 63 Slit, 100 Analyzing device, B1, B2, B3 Buttons, E Electron beam.

Claims

1. A method for correcting an analytical instrument using a wavelength dispersive X-ray spectrometer, comprising: the analytical device stores standard sensitivity data including a relationship between wavelength and intensity of characteristic X-rays generated from a standard sample; The correction method includes: acquiring actual measurement data including two or more data points obtained by actually measuring wavelengths and intensities of two or more different characteristic X-rays in the standard sample; calculating two or more intensity ratios that are ratios between the intensities of the two or more data points and the intensities in the standard sensitivity data corresponding to the wavelengths of the two or more data points; setting a correction coefficient line indicating the relationship between wavelength and intensity ratio based on the wavelengths of the two or more data points and the two or more intensity ratios; A correction method comprising the step of correcting the standard sensitivity data using the correction coefficient line.

2. The correcting step includes:

2. The correction method according to claim 1, further comprising the step of calculating and storing, for each wavelength, the product of the intensity ratio of the correction coefficient line and the intensity of the standard sensitivity data before correction as the intensity of the standard sensitivity data after correction.

3. The setting step comprises: The correction method according to claim 1 or 2, further comprising the step of setting a correction coefficient line that interpolates the wavelength and intensity ratio between the two or more data points.

4. The setting step includes: fitting a polynomial to the ratio of intensity to wavelength at the two or more data points; 3. The correction method according to claim 1, further comprising the step of setting the polynomial-approximated value as the correction coefficient line.

5. the acquiring step includes acquiring measured data including four or more data points obtained by actually measuring wavelengths and intensities for four or more different characteristic X-rays; The correction method according to claim 4 , wherein the step of polynomial approximation includes a step of approximating the intensity ratio of the four or more data points to a cubic equation.

6. the correcting step includes a step of setting a standard sensitivity curve by polynomial approximating the corrected standard sensitivity data, 3. The correction method according to claim 2, wherein the standard sensitivity curve is used in the analytical device to calculate the concentration of an element contained in a sample to be measured based on the intensity of characteristic X-rays emitted from the sample.

7. An analytical device using a wavelength dispersive X-ray spectrometer, a memory for storing the standard sensitivity data and the actual measurement data; An analysis device comprising: a processor that executes the correction method according to claim 1 or 2.

8. A program that causes a computer to execute the correction method according to claim 1 or 2.

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