Analysis method, automatic analysis method, and automatic analysis device

Abstract

To enable precise analysis of an object.SOLUTION: An analysis method includes: a step of irradiating a sample with electrons by a predetermined irradiation method provided with each stage of a plurality of times of irradiation or continuous irradiation; a step of detecting intensity of any of an X-ray, an electron, or current flowing through the sample generated by irradiation in each stage; and a step of obtaining a predetermined spectrum from the detected intensity in each stage, where acceleration voltage of the irradiated electron is different or bias voltage on the sample side is different in each stage of the irradiation method.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an analysis method, an automatic analysis method, and an automatic analysis device. [Background technology]

[0002] Conventionally, there are object analysis methods using X-rays and the like.

[0003] For example, there is a method using the XAFS (X-ray Absorption Fine Structure) method (see Non-Patent Document 1). The XAFS method has features such as structural information of non-crystalline materials, information by element selection, and non-destructive measurement. When non-destructive measurement is required, the XAFS method with the above features is used as one of the effective analysis tools. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "XAFS - Methods and Examples -" at the SPring-8 Synchrotron Radiation Facility URL: http: / / www.spring8.or.jp / ja / science / meetings / 2016 / 2nd_cultural_ws / xafs / Summary of the Invention [Problem to be solved by the invention]

[0005] There are several issues with analytical methods that use X-rays. First, it is difficult to reduce the irradiation area with X-rays. X-rays cannot be bent as easily as electrons, and require the complex use of crystal mirrors and other elements. Second, the use of a synchrotron radiation facility is a prerequisite. In order to continuously change the energy of the X-rays, it is necessary to use synchrotron radiation, which is a continuous beam of light.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to provide an analysis method, an automatic analysis method, and an automatic analysis device that enable precise analysis of an object. [Means for solving the problem]

[0007] The analytical method disclosed herein comprises the steps of irradiating a sample with electrons by a predetermined irradiation method having multiple or continuous irradiation stages, detecting the intensity of any of X-rays, electrons, or current flowing through the sample generated by the irradiation at each stage, and obtaining a spectrum from the detected intensities at each stage, wherein the acceleration voltage of the irradiating electrons is different or the bias voltage on the sample side is different at each stage of the irradiation method.

[0008] The automatic analysis method disclosed herein is a method implemented on a computer, and includes the steps of irradiating a sample with electrons using a predetermined irradiation method having multiple or continuous irradiation stages, and detecting the intensity of either X-rays, electrons, or a current flowing through the sample generated by the irradiation at each stage, obtaining a spectrum from the detected intensities at each stage, and acquiring information about the sample from the spectrum, wherein the acceleration voltage of the irradiating electrons is different or the bias voltage on the sample side is different at each stage of the irradiation method.

[0009] The automatic analysis device of the present disclosure includes an irradiator that irradiates a sample with electrons, a detector that detects the intensity of either X-rays, electrons, or a current flowing through the sample generated by the irradiation, an automatic control unit that controls the irradiator to irradiate electrons to the sample using a predetermined irradiation method that has multiple or continuous irradiation stages, and controls the detector to detect the intensity at each stage, a generation unit that generates a spectrum from the intensity at each stage detected by the detector, an analysis unit that analyzes the sample from the generated spectrum, and an output control unit that displays or stores the analysis results obtained by the analysis unit, and in each stage of the irradiation method, the acceleration voltage of the irradiated electrons is different, or the bias voltage on the sample side is different. Effect of the Invention

[0010] The analysis method, automatic analysis method, and automatic analysis device of the present disclosure enable precise analysis of an object. [Brief description of the drawings]

[0011] [Figure 1] Figure 1 shows an image of the combined EDS-SEM. [Diagram 2] FIG. 2 is a block diagram showing the configuration of the automatic analysis system of this embodiment. [Diagram 3] FIG. 3 is a block diagram showing the hardware configuration of the analysis device as a computer in the automatic analysis system. [Figure 4] FIG. 4 is a flowchart showing the flow of the automatic analysis process. [Diagram 5] FIG. 5 is a diagram showing an example of an EDS spectrum. [Figure 6] FIG. 6 is a diagram showing an example of an electronic absorption spectrum. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0013] In this embodiment, a technique is proposed that combines an apparatus for irradiating a sample with electrons, such as a scanning electron microscope (SEM), with an apparatus for detecting X-rays, such as an energy dispersive X-ray analyzer (EDS). The following describes an example in which an SEM apparatus equipped with an EDS (EDS-SEM) is used. FIG. 1 is an image diagram of an EDS-SEM combination. In this embodiment, the acceleration voltage of the electron beam incident on the sample is changed to sweep the energy of the electrons, while detecting X-rays generated from the sample 114, and a spectrum (electron absorption spectrum) is obtained with the detected X-rays as its intensity. In the following, the SEM corresponds to the electron irradiator 110, and the EDS corresponds to the detector 112.

[0014] Fig. 2 is a block diagram showing the configuration of the automatic analysis system of this embodiment. As shown in Fig. 2, the automatic analysis system 100 is composed of an electron irradiator 110, a detector 112, a sample 114 to be analyzed, a bias voltage application unit 116, and an analysis device 120. Note that the reference numeral for the sample 114 will be omitted in the following description.

[0015] The analysis device 120 includes an automatic control unit 122, a generation unit 124, an analysis unit 126, and an output control unit 128. The electron irradiator 110, the detector 112, and the analysis device 120 can configure the automatic analysis device of the present disclosure.

[0016] Fig. 3 is a block diagram showing a hardware configuration of an analysis device 120 as a computer in the automatic analysis system 100. As shown in Fig. 3, the analysis device 120 has a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a storage 14, an input unit 15, a display interface (I / F) 16, and a communication interface (I / F) 17. Each component is connected to each other via a bus 19 so as to be able to communicate with each other.

[0017] The CPU 11 is a central processing unit, and executes various programs and controls each part. That is, the CPU 11 reads a program from the ROM 12 or the storage 14, and executes the program using the RAM 13 as a working area. The CPU 11 controls each of the above components and performs various arithmetic processing according to the program stored in the ROM 12 or the storage 14. In this embodiment, an image analysis program is stored in the ROM 12 or the storage 14.

[0018] The ROM 12 stores various programs and various data. The RAM 13 temporarily stores programs or data as a working area. The storage 14 is configured with a storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores various programs including an operating system, and various data.

[0019] The input unit 15 includes a pointing device such as a mouse, and a keyboard, and is used to perform various input operations.

[0020] The display interface 16 is, for example, a liquid crystal display, and displays various information. The display interface 16 may function as the input unit 15 by adopting a touch panel system.

[0021] The communication interface 17 is an interface for communicating with other devices such as terminals, and uses standards such as Ethernet (registered trademark), FDDI, and Wi-Fi (registered trademark).

[0022] Next, a description will be given of each functional component of the automatic analysis system 100. Each functional component of the analysis device 120 is realized by the CPU 11 reading out an image analysis program stored in the ROM 12 or storage 14, expanding it in the RAM 13, and executing it.

[0023] The electron irradiator 110 irradiates the sample with electrons. Note that the electrons to be irradiated are not limited to an electron beam.

[0024] The detector 112 detects the intensity of X-rays generated by irradiation. The detection is not limited to X-rays, and the intensity of electrons generated by irradiation or the current of the sample may be detected. Furthermore, the detection of the X-ray intensity is not limited to the area or height of the spectrum, and is not particularly limited as long as it is correlated with the energy of the electrons.

[0025] Here, we will explain the change in the intensity of the detected X-rays, etc. If the energy when the electrons are collided with the sample is changed, the intensity (spectrum) of the detected X-rays also changes. The energy value at which the intensity begins to appear (the lowest energy value at which the spectrum begins to rise) is a value specific to the type of element and its chemical state. Therefore, if X-rays are detected while changing the energy when the electrons are collided, it is possible to know the energy value at which the spectrum begins to rise, and from that value it is possible to identify the element and its chemical state. The energy can be changed in the following ways, so that control is performed in the automatic control unit to change the energy: (1) changing the electron acceleration voltage (changing the energy of the colliding electrons), (2) changing the voltage of the electric field on the sample side (changing the energy of the electrons at the time of collision).

[0026] Next, each component of the analysis device 120 will be described. The automatic control unit 122 controls the electron irradiator 110 and the detector 112. The automatic control unit 122 causes the irradiator to irradiate the sample with electrons by a predetermined irradiation method that has multiple or continuous irradiation stages. The automatic control unit 122 controls the detector 112 to detect the intensity at each stage of irradiation. Here, at each stage of the irradiation method, the acceleration voltage of the electrons irradiated from the electron irradiator 110 is controlled to be different due to the change in intensity. Note that, not limited to the acceleration voltage of the electrons, the application unit 116 may be controlled to change the intensity, and the bias voltage on the sample side may be controlled to be different. The polarity of the bias voltage to the sample may be either positive or negative. The generation unit 124 generates multiple EDS spectra according to the aspect of the changed voltage.

[0027] The generation unit 124 generates an EDS spectrum from the intensity of each stage detected by the detector 112. Here, when the electron acceleration voltage is controlled to be different, a plurality of EDS spectra with different acceleration voltages of the irradiated electrons are generated as the EDS spectrum. When the bias voltage on the sample side is controlled to be different, a plurality of spectra with different bias voltages on the sample side are generated as the EDS spectrum. Note that instead of the EDS spectrum, a spectrum of electrons or a specimen current may be generated. Examples of the generated EDS spectrum, analysis, and display will be described in the experimental examples below. The EDS spectrum, the spectrum of electrons, or the spectrum of specimen current are examples of the "predetermined spectrum" in this disclosure.

[0028] The analysis unit 126 performs analysis of the sample from the generated spectrum. For example, analysis is possible by plotting the intensity of multiple EDS spectra against the energy of the incident electron beam. Sample information can be obtained by analysis. Here, it is possible to analyze the rising energy shown in multiple spectra, that is, the absorption edge. Since the rising edge has characteristics depending on the type of object, this allows precise identification of the object. Alternatively, the intensity of each detected step may be mapped without using a spectrum.

[0029] The output control unit 128 displays (or stores) the analysis results obtained by the analysis unit 126. The output control unit 128 can display spectrum graphs, analyzed numerical values, and the like as the analysis results.

[0030] Next, the operation of the automatic analysis system 100 according to this embodiment will be described. Fig. 4 is a flowchart showing the flow of the automatic analysis process. The CPU 11 reads out an automatic analysis program from the ROM 12 or the storage 14, deploys it in the RAM 13, and executes it, thereby performing the automatic analysis process as an automatic analysis method.

[0031] In step S100, the CPU 11, as the automatic control unit 122, causes the electron irradiator 110 to irradiate the sample with electrons by a predetermined irradiation method having multiple or continuous irradiation stages. Note that the CPU 11 causes the application unit 116 to apply a voltage to the sample at any timing in accordance with the irradiation.

[0032] In step S102, the CPU 11, functioning as the automatic control unit 122, controls the detector 112 to detect the intensity at each stage of irradiation.

[0033] In step S104, the CPU 11 functions as the generation unit 124 to generate a spectrum from the detected intensities at each stage.

[0034] In step S106, the CPU 11, functioning as the analysis unit 126, analyzes the sample from the generated spectrum.

[0035] In step S108, the CPU 11 functions as the output control unit 128 to display (or store) the obtained analysis results.

[0036] As described above, the automatic analysis system according to this embodiment enables precise analysis of an object.

[0037] [Experimental Example] An experimental example of this embodiment will be described. In the experiment, (1) Si (a substrate from which the natural oxide film on the surface has been removed) and (2) SiO2 (a thermal oxide film formed on a Si substrate) were used as samples. FIG. 5 shows an example of an EDS spectrum. The spectrum in FIG. 5 is an EDS spectrum of Si when the accelerating voltage (energy) of the incident electron beam is changed. FIG. 6 shows an example of an electronic absorption spectrum. The intensity information of these EDS spectra, for example, the peak area, is plotted against the energy of the incident electron beam to obtain an electronic absorption spectrum. The rising energy (absorption edge) differed from that of Si, starting from 1.84 keV, to that of SiO2, starting from 1.85 keV. The graph of the electronic absorption spectrum, the rising energy, and the like can be obtained as information obtained by analyzing the sample through the analysis of the analysis unit 126. This result is not inconsistent with the result obtained by X-ray absorption spectroscopy, which is a conventional technique described in Reference 1. In this way, it was confirmed by the experiment that the present method can identify the chemical state. [Reference 1] N. Isomura et al., Appl. Surf. Sci. 355 (2015) 268

[0038] By applying the method of automatic analysis of this embodiment, the following precise analysis becomes possible. (1) Elements can be identified. This is because the energy value of the absorption edge (rise of intensity) in the absorption spectrum is element-specific. (2) Chemical states can be identified. This is because the energy value of the absorption edge (rise of intensity) in the absorption spectrum and the spectrum shape differ depending on the chemical state. (3) Micro-area measurement becomes possible. This is because the irradiation area can be made small by using an electron lens or the like, as in the case of electrons used in electron microscopes. (4) Information on the surface of the sample can be obtained. This is because the electron beam does not penetrate deeply into the sample. (5) The same location as that of a scanning electron microscope can be measured. (6) Unlike X-ray absorption spectroscopy, this can be realized inexpensively with a laboratory device without using a large facility. This is because the basic device configuration is the same as that of a scanning electron microscope equipped with an X-ray detector. (7) A chemical state inspection device can also be realized. This is because the minimum device configuration is an electron gun and an X-ray detector.

[0039] The present disclosure is not limited to the above-described embodiment, and various modifications and applications are possible without departing from the scope of the present invention. For example, the generation unit 124 may generate a differential spectrum of a minute signal using a lock-in amplifier.

[0040] The automatic analysis process executed by the CPU by reading the software (program) in the above embodiment may be executed by various processors other than the CPU. Examples of the processor in this case include a PLD (Programmable Logic Device) whose circuit configuration can be changed after manufacturing such as an FPGA (Field-Programmable Gate Array), and a dedicated electric circuit which is a processor having a circuit configuration designed exclusively for executing a specific process such as an ASIC (Application Specific Integrated Circuit) or a GPU (Graphics Processing Unit). The automatic analysis process may be executed by one of these various processors, or may be executed by a combination of two or more processors of the same or different types (for example, a plurality of FPGAs, a combination of a CPU and an FPGA, etc.). The hardware structure of these various processors is, more specifically, an electric circuit that combines circuit elements such as semiconductor elements.

[0041] In the above embodiment, the program for the automatic analysis process is stored (installed) in advance in a ROM or storage, but the present invention is not limited to this. The program may be provided in a form recorded on a non-transitory recording medium such as a CD-ROM (Compact Disk Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), or a USB (Universal Serial Bus) memory. The program may also be downloaded from an external device via a network. [Explanation of symbols]

[0042] 100 Automated Analysis System 110 Electron irradiator 112 Detector 114 Samples 116 Applicator 120 Analyzer 122 Automatic control unit 124 Generation part 126 Analysis Department 128 Output control section

Claims

1. irradiating the sample with electrons using a predetermined irradiation regime including multiple or successive irradiation stages; detecting the intensity of any of X-rays, electrons, or current flowing through the sample generated by the irradiation at each stage; and obtaining a predetermined spectrum from the detected intensities of each step. In each stage of the irradiation method, the acceleration voltage of the irradiated electrons is different, or the bias voltage on the sample side is different. Analysis method.

2. 1. A computer-implemented method comprising: a step of irradiating a sample with electrons by a predetermined irradiation method having multiple or continuous irradiation steps, and detecting the intensity of any of X-rays, electrons, or current flowing through the sample generated by the irradiation at each step; Obtaining a predetermined spectrum from the intensities of each detected step; and acquiring information about the sample from the spectrum. In each stage of the irradiation method, the acceleration voltage of the irradiated electrons is different, or the bias voltage on the sample side is different. Automatic analysis method.

3. The step of obtaining the spectrum includes obtaining a plurality of the spectra at each stage, 3. The automatic analysis method according to claim 2, wherein the step of acquiring information about the sample comprises analyzing an electronic absorption spectrum obtained with respect to the energy of the incident electron beam using information about the intensities of the spectra.

4. an irradiator for irradiating the sample with electrons; a detector for detecting the intensity of any of X-rays, electrons, or a current flowing through the sample generated by the irradiation; an automatic control unit that controls the illuminator to irradiate electrons onto the sample by a predetermined irradiation method having multiple or continuous irradiation steps, and controls the detector to detect the intensity at each step; A generation unit that generates a predetermined spectrum from the intensity of each stage detected by the detector; an analysis unit that analyzes a sample from the generated spectrum; an output control unit that displays the analysis result obtained by the analysis unit; In each stage of the irradiation method, the acceleration voltage of the irradiated electrons is different, or the bias voltage on the sample side is different. Automatic analyzer.

5. The generation unit generates a plurality of spectra at each stage as the spectrum, 5. The automatic analyzer according to claim 4, wherein the analysis section analyzes the electronic absorption spectrum obtained for each energy of the incident electron beam using information on the intensities of the spectra.

6. The automatic control unit controls the voltage of the electrons from the irradiator or the voltage from the application unit to change the intensity, When controlling the irradiator due to the change in intensity, the irradiator is controlled so that an acceleration voltage of electrons irradiated from the irradiator is different, and the generation unit is caused to generate a plurality of spectra having different acceleration voltages of the irradiated electrons as the spectrum; The automatic analyzer of claim 4, wherein when the application unit is controlled to change the intensity, the bias voltage on the sample side from the application unit is controlled to be different, and the generation unit is caused to generate a plurality of spectra with different bias voltages on the sample side as the spectrum.

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