X-ray analysis device
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Patents
- Current Assignee / Owner
- HITACHI HIGH TECH SCIENCE CORP
- Filing Date
- 2021-06-03
- Publication Date
- 2026-08-01
AI Technical Summary
Existing fluorescent X-ray analysis methods struggle to efficiently measure the composition and film thickness of small samples without requiring stationary positioning and high-definition optical systems, leading to inefficiencies and increased costs due to the need for precise sample alignment and complex mechanical adjustments.
An X-ray analyzer that includes an X-ray irradiation unit, detection unit, sample transport unit, and data processing unit, which continuously acquires and analyzes X-ray intensity data to determine sample position within the irradiation area using threshold values and machine learning, eliminating the need for stationary positioning and complex alignment mechanisms.
Enables efficient, cost-effective measurement of multiple small samples by continuously analyzing X-ray intensity, allowing for simple structure and rapid analysis without the need for precise sample alignment, thus improving throughput and reducing system complexity.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a fluorescence X-ray analysis apparatus for determining the composition of a sample and the thickness of a coating membrane. [Previous Technology]
[0002] X-ray fluorescence analysis is a method that involves irradiating a sample with X-rays to excite the elements contained in the sample, and then analyzing the characteristic X-rays of the elements emitted as a result of the excitation. The resulting X-ray fluorescence spectrum contains information related to the amount of elements present in the X-ray irradiated region. Therefore, by using an appropriate model to analyze the spectrum, the composition ratio of the sample, the thickness of multilayer films, etc., can be determined. In most cases, these analyses can be performed non-destructively and non-contactly, and are therefore sometimes used for quality management of industrial products, such as film thickness testing of coatings as defined in JIS H8501. Regarding X-ray fluorescence analysis, according to its principle, the area irradiated by X-rays is called the analytical object area. Therefore, it is necessary to appropriately limit the irradiation diameter of the X-rays corresponding to the size of the measurement area, and to obtain the X-ray fluorescence spectrum while the analytical object is correctly positioned within the X-ray irradiation area. As a fluorescence X-ray analysis apparatus that obtains fluorescence X-ray spectra while correctly irradiating an object area with X-rays, the sample, which is the object to be measured, is placed on a sample stage capable of orthogonal 2-axis or 3-axis drive. After adjusting the position of the sample so that the measurement area of the sample is positioned at the X-ray irradiation position, the measurement is performed while the sample is stationary. At this time, an optical system is generally set up to focus the lens at the center of the field of view for the X-ray irradiation position and observe the sample using an optical unit, and the sample is adjusted to the X-ray irradiation position using this optical system. (See Patent Document 1) Furthermore, in the case of a fluorescence X-ray analysis apparatus used to measure the thickness of a coating film on the surface of a strip-shaped sample, the following method is sometimes adopted: the sample is continuously transported so that it passes through the X-ray irradiation position and the measurement is performed simultaneously; during the measurement time, the average information of the area along the line at the X-ray irradiation position is analyzed. Compared with the aforementioned method of adjusting the sample position and performing the measurement while stationary, the time required for sample position adjustment is eliminated, allowing for efficient inspection of multiple areas. However, this method is applicable to situations where the objects being measured are continuously distributed on a long strip of sample, but not to situations where a large number of small samples are intermittently transported. Therefore, by automating the position adjustment, a large number of samples placed on the sample stage can be automatically detected, thus achieving high efficiency in the measurement. Several methods exist for automatic adjustment of the sample position, one of which is the method using an optical sample observation image. An optical sample observation unit is set up as described above, and using the sample image obtained therefrom, image processing techniques, primarily pattern matching, are used to detect the offset between the irradiation position and the sample. The sample stage is then controlled according to this offset to position the sample at the X-ray irradiation position. This first method is based on the premise that the image of the optical sample observation unit is consistent with the X-ray irradiation position, or that the relative positions of the axes are accurately known.However, these relative positional relationships can sometimes shift due to changes over time or thermal expansion. The smaller the object being measured, the more significant the impact of the shift in the observation optical axis and the X-ray irradiation axis becomes. In this case, as a second method, Patent Document 2 discloses a method for correcting the sample position using the relationship between the stage coordinates and the X-ray intensity. Patent Document 1: Japanese Patent Application Publication No. 06-273147 Patent Document 2: Japanese Patent Application Publication No. 06-273146 In the aforementioned prior art, the process involves adjusting the position of the sample and measuring the sample in a stationary state. Since adjusting the position of the sample takes time, inspecting a large number of samples in a short period of time becomes a problem. Furthermore, there is the problem that a high-precision sample observation optical system and a high-precision multi-axis sample stage are required, making the measurement system expensive. [Summary of the Invention]
[0003] The present invention was made in view of the aforementioned problems, and its object is to provide an X-ray analysis apparatus capable of continuously measuring a large number of small samples while they are not stationary. To solve the aforementioned problems, the X-ray analysis apparatus of the present invention is characterized by comprising: an X-ray irradiation unit that irradiates a sample with X-rays; an X-ray detection unit that detects secondary X-rays generated from the sample; a sample transport unit that transports the sample; an analyzer that continuously acquires an X-ray spectrum of the X-ray intensity of the secondary X-rays detected by the X-ray detection unit at time intervals shorter than the time required for the sample to pass through the X-ray irradiation position; and determines whether the sample being moved by the sample transport unit is passing through the X-ray irradiation position based on the secondary X-ray intensity of the energy of a specific element in the spectrum obtained by the analyzer and a set threshold value for the X-ray intensity. The X-ray analysis apparatus of the present invention is characterized in that the aforementioned data processing unit compares the X-ray intensity of the energy of a specific element of the sample with the set threshold value for the X-ray intensity to determine whether the sample is located in the X-ray irradiation unit. The X-ray analysis apparatus of the present invention is characterized in that the aforementioned data processing unit compares the X-ray intensity of a specific element of the material of the sample conveying section surface with a set threshold value of X-ray intensity to determine whether the sample is located in the X-ray irradiation section. The X-ray analysis apparatus of the present invention is also characterized in that the aforementioned data processing unit compares the X-ray intensity of the scattered rays of a primary X-ray with a set threshold value of X-ray intensity to determine whether the sample is located in the X-ray irradiation section. A fifth aspect of the present invention for solving the above-mentioned problems, in the first aspect, is characterized in that the aforementioned data processing unit selects the spectrum at the moment the sample is located in the aforementioned X-ray irradiation section from the spectral feature quantities obtained by machine learning. A sixth aspect of the present invention for solving the above-mentioned problems, in the first to fifth aspects, is characterized in that an X-ray spectrum composed of a histogram of X-ray counts formed by equally spaced continuous energy or wavelength ranges is used. A seventh aspect of the present invention for solving the above-mentioned problems, in the first to fifth aspects, is characterized in that an X-ray spectrum based on counts of a specific energy range or a combination thereof is used. Effects of the Invention According to the present invention, the fluorescence X-ray analysis apparatus can be calibrated by means of an X-ray irradiation unit capable of irradiating the sample with X-rays, an X-ray detection unit for detecting secondary X-rays generated from the sample, a sample conveying unit for conveying the sample, and a data processing unit for processing the intensity of the detected X-rays. The position adjustment mechanism for arranging the sample in the primary X-ray irradiation area and the position adjustment process are omitted, and it can be implemented with a simple structure.
Implementation Method
[0005] Hereinafter, embodiments of the X-ray analysis apparatus of the present invention will be described with reference to the accompanying drawings. The X-ray analysis apparatus of this embodiment includes: a sample transport unit 3 capable of carrying a sample S and moving it in a transport direction D; an X-ray irradiation unit 1 that irradiates the sample S with a primary X-ray X1; a primary X-ray adjustment unit 4 that shapes the irradiation diameter of the primary X-ray X1 irradiating the sample; an X-ray detection unit 2 that detects secondary X-rays such as scattered X-rays or fluorescent X-rays generated from the sample S irradiated with the primary X-ray X1; an analyzer 5 connected to the X-ray detector 2 that analyzes the signal of energy information of the secondary X-rays; and a data processing unit 7 connected to the analyzer 5. Figure 1 shows the case where the sample S is not located at the irradiation position 6. Figure 3 shows the case where the sample S is located at the irradiation position 6. The X-ray irradiation unit 1 that irradiates the sample S with a primary X-ray X1 is an X-ray tube. The X-ray tube is housed in a casing that provides adequate insulation against the applied high voltage, shields X-rays from unwanted directions for safety, and includes a cooling mechanism to dissipate the generated heat. The primary X-ray adjustment unit 4 can utilize, for example, a collimator with fine apertures made of tungsten or brass with sufficient X-ray shielding capacity, or an X-ray focusing element such as a multi-capillary or single-capillary tube utilizing total internal reflection from the inner surface of a hollow glass tube. The irradiation diameter formed by the primary X-ray adjustment unit 4 is determined based on the size of the sample S and the conveying speed of the sample conveying unit 3, which carries the sample S and moves it in the conveying direction D. When the arrangement of the sample S in a direction orthogonal to the conveying direction D is not negligible relative to the sample size, its offset is also considered when determining the irradiation diameter. For example, an irradiation diameter is set to the extent that the sample size is reduced by a predetermined arrangement offset. Thus, when the sample is in the irradiation position, the generated fluorescence X-rays are considered to originate entirely from the sample in practical applications. The sample conveying unit 3 is a belt conveyor formed by winding an annular belt around a pair of rollers, capable of continuously conveying the sample S in a relatively movable manner along a specified scanning direction. The surface material of the sample conveying unit 3, which carries the sample S, is selected such that the energy of the secondary X-rays generated from the sample S does not interfere with the energy of the secondary X-rays generated from the surface of the sample conveying unit 3. For example, if the sample S is made of copper (Cu) or nickel (Ni), the surface material of the sample conveying unit 3 is aluminum (Al). Furthermore, the sample conveying unit 3 is configured such that the trajectory of the carried sample S passes through the irradiation position 6 irradiated by the primary X-ray X1. Here, the irradiation diameter of the primary X-ray X1 is considered to limit the arrangement of samples in the direction orthogonal to the sample conveying direction D. However, regarding the arrangement of samples in the conveying direction D, i.e., the interval between each conveyed sample S, the measurement should at least have a gap of one sample between two consecutive samples. If the gap is larger than this, there is no restriction, and equal intervals are not required.Regarding the shape of the sample conveyor 3, it is not limited to a disc shape, except for a belt conveyor. The trajectory of the conveyed sample intersects with the primary X-ray X1. Furthermore, only one sample can be conveyed. The X-ray detection unit 2 uses an energy-dispersive X-ray detector such as a semiconductor detector or a proportional counter tube. This X-ray detection unit 2 generates a charge proportional to the energy of the single incident X-ray photon, converts it into a voltage signal proportional to that charge, performs an AD conversion, and outputs it as a digital value. Alternatively, the X-ray detection unit 2 can also use a wavelength-dispersive X-ray detector. The analyzer 5 is connected to the X-ray detection unit 2 and analyzes the signal. The analyzer 5 is, for example, a wave height analyzer (multi-channel analyzer) that obtains the wave height of the voltage pulse from the signal and generates an energy spectrum. The analyzer 5 distinguishes the signal of the X-ray photon output from the X-ray detection unit 2 according to each energy, counts the number of incidents according to each energy, and obtains the spectrum as the X-ray intensity. In Figure 7, the analyzer 5 distinguishes each energy level and counts the number of injections for each energy level. Regarding X-ray intensity, multiple channels 42, each representing an energy level divided by an equal interval ΔE, are arranged, and the arrangement of the counts for each channel 42 is shown. The time Tm for accumulating the injection count is set as shown in Formula 1 below. [Formula 1] Tm < L / V Here, L is the length of the measurement object portion on the sample S in the transport direction D, and V is the transport speed of the sample S. Here, as an example, Tm is set to 1 / 10 of L / V. Furthermore, it is preferable that the time Tm for accumulating the injection count is shorter than the time required for the sample to pass through the aforementioned X-ray irradiation unit. This spectral accumulation operation is continuously performed, and the resulting spectra are stored in the memory of the data processing unit 7 as a spectral arrangement. The data processing unit 7 determines, based on the obtained spectra and the set threshold, whether the sample S being moved by the sample transport unit 3 is being irradiated at position 6. Furthermore, the spectra stored in the memory of the data processing unit 7 are updated in order from oldest to newest, thus preventing the storage area from becoming saturated. However, by installing the memory in a way that allows for a sufficient number of spectra to be written at once, it will not be updated by the next spectrum within the time required for subsequent processing. The aforementioned analyzer 5 is a wave height analyzer (multi-channel pulse height analyzer) that obtains the wave height of the voltage pulse based on the signal from the X-ray detection unit 2 and generates an energy spectrum. In the data processing unit 7, the successively acquired spectra are monitored, and the changes in the energy spectrum caused by the presence or absence of the sample S are detected. The case where the main component of the material of the sample transport unit 3 is element A, and the sample S contains element B as its main component, will be explained. Figure 2 shows the spectrum 10 when the sample S is not located at the irradiation position 6 as shown in Figure 1, with the horizontal axis representing energy and the vertical axis representing X-ray intensity.Since the surface of the sample conveying section 3 is located at the irradiation position 6, the spectrum 10 shows a peak in X-ray intensity at energy 11 of the fluorescent X-rays of element A, which is the main component of the material of the sample conveying section 3. Next, Figure 4 shows the spectrum 12 when the sample S is located at the irradiation position 6 as shown in Figure 3. Since the sample S is located at the irradiation position 6, the spectrum 12 shows a peak in X-ray intensity at energy 13 of the fluorescent X-rays of element B, the main component of the sample S. At this time, the X-ray intensity of energy 11 of the fluorescent X-rays of element A in Figure 4 is smaller than that in Figure 2. Utilizing this property, a predetermined threshold value 14 of X-ray intensity is set. When the X-ray intensity of energy 13 of the fluorescent X-rays of element B, the main component of the sample S, is higher than the threshold value 14, it is determined that the sample S is present at the irradiation position 6. In this embodiment, since Tm is set to 1 / 10 of L / V as described above, Figure 5 shows the spectra T1~T21 continuously measured at predetermined time intervals while the sample S is being conveyed. In the case of Figure 5, in spectra T2-T20, the X-ray intensity of the fluorescence X-ray energy 13 of element B is greater than the critical value 14. Therefore, it is determined that sample S is located at irradiation position 6. The determined X-ray intensity of energy 13 is analyzed as the sample's measurement spectrum. All of these continuous measurement spectra are treated as separate spectra. Alternatively, as with spectra T2 and T20, the first and last measurement spectra can be excluded, and T3-T29 can be accumulated or averaged and treated as a single spectrum. Alternatively, the center or centroid of the continuous measurement spectra can be selected as the sample's spectrum, etc. The X-ray analysis apparatus of this embodiment described above uses the X-ray intensity of the fluorescence X-ray energy 13 of element B, the main component of sample S, to determine whether sample S is present at irradiation position 6. However, it is also possible to use the X-ray intensity and a specific critical value based on the fluorescence X-ray energy of the main component of the sample conveying part material, i.e., element A, to determine whether a sample is present. In addition, the critical value in this case may be different from the critical value of this embodiment described above. As shown in Figures 2 and 4, the X-ray intensity of the fluorescence X-ray energy 11 of element A, which is the material of the sample conveying section 3, also varies depending on the position of the sample S. When the sample S is located at the irradiation position 6, the amount of primary X-ray X1 irradiating the sample conveying section 3 decreases, and the X-ray intensity of the fluorescence X-ray energy 11 of element A decreases significantly. By setting a specific threshold value for element A and comparing the X-ray intensity of the fluorescence X-ray energy 11 of element A with that threshold value, it is possible to determine whether the sample S is located at the irradiation position 6. Furthermore, in another X-ray analysis apparatus of this embodiment, when the surface of the sample conveying section 3 is made of plastic material, the scattering efficiency of primary X-rays from plastic is high, and the peaks of fluorescence X-rays from the main components of plastic, namely carbon or oxygen, are almost undetectable.Therefore, when sample S is not located at irradiation position 6, as shown in spectrum 15 of FIG6, the spectrum of scattered rays is significantly broad compared to the fluorescent X-ray peak, reflecting the continuous X-ray composition from the X-ray tube. Utilizing this property, it is possible to determine whether the spectrum indicates sample S is located at irradiation position 6 when the X-ray intensity in energy region 16, where the intensity of scattered rays that do not interfere with the energy 13 of the main component element B of sample S is significantly lower than the critical value 17. Furthermore, in another X-ray analysis apparatus of this embodiment, the case where selection is not made in a manner where the fluorescent X-rays of the material of sample S do not interfere with the fluorescent X-rays of sample S, and the case where the composition of sample S is unstable and it is difficult to set an appropriate critical value, is described. As a preparation stage, multiple spectra are obtained in a state where sample S is not placed, and then the spectrum is obtained when the sample is placed at or near the irradiation position. Note that when predicting differences in the spectra between samples caused by individual sample differences other than deviations in the measurement system such as deviations in sample composition or coating thickness, the spectra of multiple samples appropriately reflect the deviations in individual sample differences. The differences between the two sets of spectra are learned using deep learning. Using the learning results obtained in the preparation phase so far, it is determined whether the spectrum represents the sample S located at irradiation position 6. As shown in Figure 7, the spectrum generated by the X-ray detection unit 2 is arranged by counting each energy range at equal intervals. In this case, the X-ray intensity of the energy 11 of the fluorescent X-rays of the principal component of the sample conveying unit material, element A, is given as a value obtained by summing the counts of the channels between energies EA0 and EA1. Similarly, the X-ray intensity of the energy 13 of the X-rays of the principal component of sample S, element B, is also given as a value obtained by summing the counts of the channels between energies EB0 and EB1. In subsequent data processing, this method is meaningful when the peak shape of the spectrum is important; however, in subsequent data processing, when the sum of the counts between EA0 and EA1 and between EB0 and EB1 is sufficient for the fluorescent X-ray intensities of each element, it is not necessary to generate the spectrum by dividing the channels at equal intervals. In this case, instead of dividing the channels at equal intervals, the energy region of the energy peak containing the necessary elements is set as several channels, and multiple single-channel analyzers are operated, thereby achieving the purpose of the present invention. [Simplified Explanation of the Diagram]
[0004] [Figure 1] is a schematic overall structural diagram of the X-ray apparatus in an embodiment of the fluorescence X-ray apparatus of the present invention, in a state where the sample has not been irradiated with X-rays once. [Figure 2] is a spectrum showing the state where the sample has not been irradiated with X-rays once. [Figure 3] is a schematic overall structural diagram of the X-ray apparatus in an embodiment of the fluorescence X-ray apparatus of the present invention, in a state where the sample has been irradiated with X-rays once. [Figure 4] is a spectrum showing the state where the sample has been irradiated with X-rays once. [Figure 5] is a spectrum showing the continuous measurement at predetermined time intervals while the sample is being transported. [Figure 6] is a spectrum showing the case where the sample transport section is made of plastic. [Figure 7] is a spectrum showing the energy channels divided according to equal intervals ΔE.
Claims
1. An X-ray analysis apparatus, characterized in that the X-ray analysis apparatus comprises: an X-ray source capable of irradiating a sample with X-rays; an X-ray detection unit that detects secondary X-rays generated from the sample; a sample conveying unit that conveys the sample; an analyzer that distinguishes signals output from the X-ray detection unit according to each energy, counts the number of injections according to each energy, and obtains a spectrum as X-ray intensity; and a data processing unit that determines whether the sample being moved by the sample conveying unit is passing through the irradiation position of the X-rays based on the secondary X-ray intensity of a specific element in the spectrum obtained by the analyzer and a set threshold value of the X-ray intensity; pre-measuring the X-ray intensity of a specific element of the surface material of the sample conveying unit when the sample is not located at the irradiation position of the X-rays, and setting it as a first X-ray intensity; when the sample is located at the irradiation position of the X-rays, and its X-ray intensity is set as a second X-ray intensity; the data processing unit sets the X-ray intensity between the first X-ray intensity and the second X-ray intensity as the threshold value.
2. An X-ray analysis apparatus, characterized in that the X-ray analysis apparatus comprises: an X-ray source capable of irradiating a sample with X-rays; an X-ray detection unit that detects secondary X-rays generated from the sample; a sample conveying unit that conveys the sample; an analyzer that distinguishes signals output from the X-ray detection unit according to each energy, counts the number of injections according to each energy, and obtains a spectrum as X-ray intensity; and a data processing unit that determines whether the sample being moved by the sample conveying unit is passing through the irradiation position of the X-rays based on the secondary X-ray intensity of a specific element in the spectrum obtained by the analyzer and a set threshold value of the X-ray intensity; pre-measuring the X-ray intensity of a specific element of the surface material of the sample conveying unit when the sample is not located at the irradiation position of the X-rays, and setting it as a first X-ray intensity; and the data processing unit setting a value lower than the first X-ray intensity as the threshold value.
3. An X-ray analysis apparatus, characterized in that the X-ray analysis apparatus comprises: an X-ray source capable of irradiating a sample with X-rays; an X-ray detection unit that detects secondary X-rays generated from the sample; a sample conveying unit that conveys the sample; an analyzer that distinguishes signals output from the X-ray detection unit according to each energy, counts the number of injections according to each energy, and obtains a spectrum as X-ray intensity; and a data processing unit that determines whether the sample being moved by the sample conveying unit is passing through the irradiation position of the X-rays based on the secondary X-ray intensity of the energy of a specific element in the spectrum obtained by the analyzer and a set threshold value of the X-ray intensity; pre-measuring and obtaining multiple X-ray intensities of the energy of a specific element of the surface material of the sample conveying unit when the sample is not located at the irradiation position of the X-rays, and setting them as a first X-ray intensity group; obtaining multiple X-ray intensities when the sample is located at or near the irradiation position of the X-rays, and setting them as a second X-ray intensity group; The aforementioned data processing unit learns the differences in each spectrum between the aforementioned first X-ray intensity group and the aforementioned second X-ray intensity group through machine learning, and determines whether the aforementioned sample is being irradiated by the aforementioned X-rays based on the spectral feature values obtained by the machine learning.
4. The X-ray analysis apparatus according to claim 1, wherein, The aforementioned analyzer continuously acquires the spectrum of the X-ray intensity of the secondary X-rays detected by the aforementioned X-ray detection unit at time intervals shorter than the time required for the aforementioned sample to pass through the aforementioned irradiation position of the X-rays.
5. The X-ray analysis apparatus according to any one of claims 1 to 4, wherein, An X-ray spectrum consists of a histogram of X-ray zero counts, which is formed by dividing a continuous range of energy or wavelength at equal intervals.
6. The X-ray analysis apparatus according to any one of claims 1 to 4, wherein the X-ray spectrum is a count of a specific energy range or a combination thereof.