KR20220004545A - Apparatus for x-ray analysis - Google Patents

Abstract

An X-ray fluorescence analysis apparatus is provided. Provided is a method for continuously measuring a large number of small samples by a simple configuration without requiring a position adjustment mechanism and a position adjustment process for disposing a sample in a primary X-ray (X1) irradiation region. An X-ray fluorescence analysis device is configured to include: an X-ray irradiation unit capable of irradiating a sample with X-rays; an X-ray detection unit detecting secondary X-rays generated from the sample; a sample transport unit transporting the sample; and a data processing unit processing the intensity of the detected X-rays, and each constituent element has the following functions. The sample transport unit moves the sample such that the sample passes through the X-ray irradiation position. The X-ray detection unit continuously acquires an X-ray spectrum at a time interval shorter than the time required for the sample to pass through the X-ray irradiation unit. The data processing unit selects a spectrum, at the time when the sample is located in the X-ray irradiation unit, from the arrangement of the continuously acquired X-ray spectrums on the basis of the characteristics of the X-ray spectrums.

Description

X-ray analysis device {APPARATUS FOR X-RAY ANALYSIS}

The present invention relates to a fluorescent X-ray analyzer for measuring a composition of a sample or a film thickness of a coating.

Fluorescence X-ray analysis is a method of excitation of an element contained in a sample by irradiating X-rays to the sample, and analyzing the characteristic X-rays inherent to the element emitted as a result. Since the obtained fluorescence X-ray spectrum contains information related to the amount of elements present in the area irradiated with X-rays, it is possible to obtain the composition ratio of the sample or the film thickness of the multilayer structure by analyzing the spectrum with an appropriate model. have. Since such an analysis process can be performed non-destructively and non-contact in many cases, it may be used for quality control of industrial products, such as a plating film thickness test defined by JIS H8 501.

From the principle of fluorescence X-ray analysis, the area irradiated with X-rays becomes an area to be analyzed. Therefore, it is necessary to appropriately limit the irradiation diameter of the X-ray to be irradiated according to the size of the measurement area, and to acquire the X-ray fluorescence spectrum in a state where the measurement target site is correctly arranged in the area to be irradiated with X-rays.

A fluorescence X-ray analyzer that acquires a fluorescence X-ray spectrum when a target area is correctly irradiated with X-rays. A sample to be measured is placed on a sample stage capable of orthogonal biaxial or triaxial driving, and the measurement site of the sample is After adjusting the position of the sample so as to be disposed at the X-ray irradiation position, the measurement is performed in a state where the sample is stationary. At this time, it is also widely practiced to provide an optical system for observing the sample by optical means by focusing the X-ray irradiation position with the center of the field of view, and using this to adjust the sample to the X-ray irradiation position. (See Patent Document 1)

Moreover, in the case of a fluorescent X-ray analysis apparatus for measuring the thickness of a film provided on the surface of a long sheet-shaped sample, the measurement is performed while continuously sending the sample so as to pass through the X-ray irradiation position, and X-rays are performed during the measurement period. In some cases, a method of analyzing the irradiation position and the average information of the area on the line that has passed may be taken. Compared with the method of adjusting the position of the sample and measuring in a stationary state, the time for adjusting the position of the sample becomes unnecessary and it is possible to efficiently inspect many sites.

However, this method is applicable to a case in which the measurement target is continuously distributed in a long sample, and cannot be applied to a case in which a large number of small samples are intermittently sent.

Therefore, measurement efficiency has been improved by automatically detecting a large number of samples arranged on the sample stage by automating the position adjustment.

There are several approaches to automatic adjustment of the sample position, one of which is based on an optical sample observation image. The optical sample observation means is provided as described above, and the deviation between the irradiation position and the sample is detected using image processing techniques such as pattern matching with the sample image obtained therefrom, and the sample stage is controlled according to the amount of deviation to collect the sample. It is to be placed at the location of X-ray irradiation.

This first approach assumes that the image of the optical sample observation means coincides with the X-ray irradiation position or that the relative positions of the axes of each other are accurately known. However, such a relative positional relationship may be shifted due to various factors, such as time-dependent change and thermal expansion. As the measurement object becomes smaller, the influence of this shift between the observation optical axis and the X-ray irradiation axis cannot be ignored.

In this case, as a second approach, Patent Document 2 discloses a method of correcting the sample position using the relationship between stage coordinates and X-ray intensity.

Japanese Patent Laid-Open No. 06-273147 Japanese Patent Laid-Open No. 06-273146

In the above prior art, the position of the sample is adjusted and the measurement is performed in a state where the sample is stopped, and since there is a time required for adjusting the position of the sample, there is a problem in order to inspect a large number of samples in a short time. Moreover, a high-quality sample observation optical system and a high-precision multi-axis sample stage are required, and there has also been a problem in that the measurement system becomes expensive.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an X-ray analyzer capable of continuously measuring a large number of small pieces without stopping the sample.

In order to solve the above problems, in the present invention, an X-ray irradiation unit for irradiating X-rays to a sample, an X-ray detection unit for detecting secondary X-rays generated from the sample, a sample conveying unit for conveying the sample, and an X-ray detection unit An analyzer that continuously acquires an X-ray spectrum at a time interval shorter than the time required for the sample to pass through the X-ray irradiation unit for the X-ray intensity of the detected secondary X-ray, and the secondary X-ray of the energy of a specific element in the spectrum obtained by the analyzer It is an X-ray analysis apparatus characterized by judging whether the sample moving in the sample conveyance part has passed the X-ray irradiation position based on the intensity|strength and the set threshold value of X-ray intensity.

The X-ray analysis device of the present invention is characterized in that the data processing unit determines whether the sample is in the X-ray irradiation unit by comparing the X-ray intensity of the energy of the specific element of the sample with the set threshold value of the X-ray intensity. .

The X-ray analysis apparatus of the present invention compares the X-ray intensity of the energy of a specific element of the material on the surface of the sample carrying unit by the data processing unit with a threshold value of the X-ray intensity to determine whether the sample is in the X-ray irradiation unit characterized in that

The X-ray analysis apparatus of the present invention is characterized in that the data processing unit determines whether the sample is in the X-ray irradiation unit by comparing the X-ray intensity of the primary X-ray scattered ray with the set threshold value of the X-ray intensity.

A fifth aspect of the present invention for solving the above problems is the first aspect, wherein the data processing unit selects a spectrum at a time point when the sample is in the X-ray irradiation unit from a feature amount of a spectrum obtained by machine learning will be.

A sixth aspect of the present invention for solving the above problems is to use an X-ray spectrum based on a histogram of X-ray coefficients obtained by dividing a continuous range of energy or wavelength at equal intervals in the first to fifth aspects.

A seventh aspect of the present invention for solving the above problems is to use the X-ray spectrum by a coefficient in a specific energy range or a combination of a plurality of them in the first to fifth aspects.

According to the present invention, an X-ray irradiation unit capable of irradiating a sample with X-rays, an X-ray detection unit detecting secondary X-rays generated from the sample, a sample conveying unit conveying the sample, and a data processing unit processing the detected X-ray intensity This makes it possible to calibrate the X-ray fluorescence analyzer, eliminates the positioning mechanism and the positioning process for arranging the sample in the primary X-ray irradiation area, and can be realized with a simple configuration.

1 is a schematic overall configuration diagram showing an X-ray apparatus in a state in which primary X-rays are not irradiated to a sample in an embodiment of the fluorescent X-ray apparatus according to the present invention.
2 is a diagram showing a spectrum in a state in which primary X-rays are not irradiated to a sample.
3 is a schematic overall configuration diagram showing an X-ray apparatus in a state in which primary X-rays are irradiated to a sample in an embodiment of the fluorescent X-ray apparatus according to the present invention.
4 is a diagram showing a spectrum of a state in which primary X-rays are irradiated to a sample.
Fig. 5 is a diagram showing a spectrum continuously measured at predetermined time intervals while conveying a sample.
Fig. 6 is a diagram showing a spectrum in the case where the sample carrying section is made of plastic.
Fig. 7 is a spectrum diagram showing a channel in which energy is divided at equal intervals (ΔE).

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the X-ray analysis apparatus which concerns on this invention is described, referring drawings.

The X-ray analysis apparatus of the present embodiment includes a sample carrying unit 3 that is movable in a carrying direction D by placing a sample S, and a primary X-ray X1 with respect to the sample S. The X-ray irradiation unit 1 to irradiate, the primary X-ray adjusting means 4 to shape the irradiation diameter of the primary X-ray X1 irradiated to the sample, and the primary X-ray X1 from the irradiated sample S An X-ray detector (2) for detecting secondary X-rays such as scattered X-rays or fluorescent X-rays, and an analyzer (5) connected to the X-ray detector (2) to analyze a signal of energy information of the secondary X-rays; The case where the data processing part 7 connected to the analyzer 5 is provided, and the sample S is not in the irradiation position 6 is shown in FIG.

Moreover, the case where the sample S exists in the irradiation position 6 is shown in FIG.

The X-ray irradiation unit 1 for irradiating the sample S with the primary X-rays X1 uses an X-ray tube. The X-ray tube is housed in a housing equipped with adequate insulation of high voltage to be applied, a cooling mechanism for discharging generated heat, and shielding of X-rays in unnecessary directions for safety. The primary X-ray adjustment means 4 is, for example, a collimator in which pores are formed in a material such as tungsten or brass having a sufficiently large X-ray shielding ability, or a polycapillary using a phenomenon of total reflection on the inner surface of a hollow glass tube. An X-ray condensing element, such as a lina monocapillary, can be used. The irradiation diameter molded by the primary X-ray adjusting means 4 is determined based on the size of the sample S and the conveying speed of the sample conveying unit 3 capable of moving in the conveying direction D by placing the sample S. do. When the arrangement of the sample S in the direction orthogonal to the conveying direction D is not negligible with respect to the size of the sample, the irradiation diameter is determined in consideration of the amount of deviation. As an example, the irradiation diameter of the grade which reduced the amount of arrangement|positioning shift assumed from the magnitude|size of a sample is set. As a result, all of the fluorescent X-rays generated when the sample is in the irradiation position can be regarded as practically all from the sample.

The sample conveying unit 3 is a belt conveyor in which an endless belt is wound around a pair of rollers, and the sample S is placed on the sample S and moved relative to the sample S in a predetermined scanning direction. ) can be conveyed continuously. The surface material of the sample transport unit 3 on which the sample S is placed does not interfere with the energy of the secondary X-rays generated from the surface of the sample transport unit 3 with respect to the energy of the secondary X-rays generated from the sample S. choose one For example, when the sample S is made of copper (Cu) or nickel (Ni), aluminum (Al) is used as the material of the surface of the sample carrying unit 3 . In addition, the sample carrying unit 3 is arranged so that the trajectory of the movement of the mounted sample S passes through the irradiation position 6 where the primary X-ray X1 is irradiated.

Here, the arrangement of the sample in the direction orthogonal to the conveying direction D of the sample is regulated in consideration of the irradiation diameter of the primary X-ray X1. ) is conveyed as the minimum limit for the state in which at least one point sample is not present between two consecutive samples. The shape of the sample conveying unit 3 is not limited to a disk shape other than a belt conveyor, and the trajectory of which the sample is conveyed intersects the primary X-ray X1.

In addition, the number of samples to be conveyed may be one.

The X-ray detection unit 2 uses an energy dispersive X-ray detector such as a semiconductor detector or a proportional counter tube. This generates a charge proportional to the energy of one incident X-ray photon, and converts it into a voltage signal proportional to the charge amount, further AD-converts it and outputs it as a digital value.

In addition, the X-ray detection unit may use a wavelength dispersion type 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 peak analyzer (multi-channel analyzer) that generates an energy spectrum by obtaining a peak height of a voltage pulse from the signal. The analyzer 5 discriminates the signal of the X-ray photon output from the X-ray detection unit 2 for each energy, counts the number of incidents for each energy, and obtains a spectrum as the X-ray intensity.

In Fig. 7, a plurality of channels 42 are arranged for each energy by the analyzer 5, the number of incidents is counted for each energy, and the energy of the spectrum as the X-ray intensity is divided at equal intervals ΔE, and each channel 42 It is shown as an array of coefficients for each. The time (Tm) for integrating this incident coefficient is set so that it may become the following expression (1).

Tm<L/V

Here, L is the length in the conveyance direction D of the measurement target part on the sample S, and V is the conveyance speed of the sample S. Here, as an example, Tm is set to 1/10 of L/V.

In addition, it is preferable that the time (Tm) for integrating the incident coefficient is shorter than the time required for the sample to pass through the X-ray irradiation unit.

This spectrum integration operation is continuously performed, and the obtained spectrum is stored in the memory of the data processing unit 7 as a spectrum arrangement. The data processing unit 7 determines whether or not the sample S moving in the sample carrying unit 3 passes through the irradiation position 6 from the obtained spectrum and the set threshold.

In addition, the spectrum stored in the memory of the data processing unit 7 is overwritten in ascending order so that the storage area does not become saturated. Make sure that the next spectrum is not overwritten within the time required for

The analyzer 5 is a peak analyzer (multi-channel pulse height analyzer) that generates an energy spectrum by obtaining the peak height of a voltage pulse from the signal from the X-ray detection unit 2 .

The data processing unit 7 monitors the spectrum acquired sequentially, and detects a change in the spectrum due to the presence or absence of the sample S.

A case will be described in which the main component of the material of the sample carrying unit 3 contains element A and the sample S contains element B as the main component. As shown in FIG. 1 , in the case where the sample S is not at the irradiation position 6, the spectrum 10 is shown in FIG. 2 when the horizontal axis represents energy and the vertical axis represents X-ray intensity. Since the surface of the sample carrying part 3 is at the irradiation position 6, the spectrum 10 shows that the main component of the material of the sample carrying part 3 has a peak of X-ray intensity at the energy 11 of the fluorescent X-ray of element A. have Next, as shown in FIG. 3 , the spectrum 12 when the sample S is at the irradiation position 6 is shown in FIG. 4 . Since the sample S is at the irradiation position 6, the X-ray intensity has a peak at the energy 13 of the fluorescent X-ray of the element B, which is the main component of the sample S. At this time, the X-ray intensity of the fluorescence X-ray energy 11 of element A in FIG. 4 is smaller than in FIG. 2 .

Using this property, a threshold 14 of a predetermined X-ray intensity is formed, and the X-ray intensity of the fluorescence X-ray energy 13 of the element B as the main component of the sample S exceeds the threshold 14 When there is, it is determined that the sample S is present at the irradiation position 6 .

In the present embodiment, since Tm is set to 1/10 of L/V as described above, as shown in Fig. 5, the spectrum T1 to T21 continuously measured at predetermined time intervals while conveying the sample S. indicates

In the case of FIG. 5 , in the spectrum T2 to T20 , the X-ray intensity of the fluorescence X-ray energy 13 of the element B is greater than the threshold value 14 . Therefore, it is determined that the sample S is at the irradiation position 6 . The X-ray intensity of the determined energy 13 is analyzed as a measurement spectrum of the sample. All these continuous measurement spectra are treated as individual spectra. Alternatively, as in the spectrum T2 or T20, the first and the last measurement spectrum may be excluded, and T3 to T29 may be integrated or averaged, and may be treated as one spectrum. Alternatively, the center or center of the continuous measurement spectrum may be selected as the spectrum of the sample, or the like.

In the X-ray analysis apparatus of the present embodiment, whether the sample S is present at the irradiation position 6 is determined by the X-ray intensity of the fluorescence X-ray energy 13 of the element B as a main component of the sample S. , the presence or absence of the sample may be judged by using the X-ray intensity and a specific threshold value for the energy of the fluorescent X-ray of element A as the main component of the material of the sample carrying unit.

In addition, the threshold value at this time may be different from the threshold value of said this embodiment.

As shown in FIGS. 2 and 4 , the X-ray intensity of the energy 11 of the fluorescent X-ray of the element A, which is the material of the sample carrying unit 3 , also changes depending on the position of the sample S. When the sample S is at the irradiation position 6, the amount of primary X-rays X1 irradiated to the sample carrying unit 3 is attenuated, and the X-ray intensity of the energy 11 of the fluorescent X-rays of the element A is greatly attenuated. By setting a specific threshold value of the element A, the X-ray intensity of the fluorescence X-ray energy 11 of the element A may be compared with this threshold to determine whether or not the sample S is at the irradiation position 6 .

Further, in the X-ray analysis apparatus of this embodiment, when the surface of the sample carrying unit 3 is made of a plastic material, the plastic has a high primary X-ray scattering efficiency, and furthermore, fluorescent X-rays of carbon or oxygen, which are the main components of the plastic, are The peak is hardly detected. Therefore, when the sample S is not located at the irradiation position 6, as shown in the spectrum 15 of Fig. 6, it is significantly compared with the fluorescent X-ray peak reflecting the continuous X-ray component from the X-ray tube. It becomes a broad spectrum of scattered rays. Using this property, the X-ray intensity of the energy region 16 where the intensity of scattered rays is remarkable, which does not interfere with the energy 13 of element B of the main component of the sample S, is less than the threshold value 17, You may determine whether it is a spectrum in the case where the sample S exists in the irradiation position 6 or not.

Further, in the X-ray analyzer of another embodiment, when the material of the sample carrying unit 3 cannot be selected so that the material of the sample S and fluorescent X-rays do not interfere, the components of the sample S are stable. This means that it is difficult to set an appropriate threshold. As a preparatory step, a large number of spectra are acquired in the state where the sample S is not mounted, and then, the spectrum in which the sample is arrange|positioned at or near the irradiation position is acquired.

If the difference in spectra between samples is predicted due to individual sample differences other than measurement system variations, such as variations in sample components or film thickness, take care to include spectra of multiple samples that appropriately reflect the individual differences between samples . The difference in the spectrum of these two groups is learned by deep learning. Using the learning result obtained in the preparation step up to this point, it is determined whether or not the sample S is a spectrum at the irradiation position 6 .

As shown in Fig. 7, the spectrum generated by the X-ray detection unit 2 was an arrangement of coefficients for each energy range divided at equal intervals. In this case, the X-ray intensity of the fluorescence X-ray energy 11 of the element A as the main component of the material of the sample carrying section was given as the sum of the coefficients of the channels between the _{energies E A0} and E _{A1 .} Similarly, the X-ray intensity of the X-ray energy 13 of the element B, the main component of the sample S, was also given as the sum of the coefficients of the channels between the _{energies E B0} and E _B1. This method makes sense when the peak shape of the spectrum is important in the subsequent data processing, but in the subsequent data processing, the fluorescence X-ray intensity of each element is determined to be _{between E A0} and E _{A1 and} between E _B0 and E _B1 , respectively. If the sum of the coefficients is sufficient, there is no need to generate a spectrum by dividing the channels at equal intervals. In such a case, the object of the present invention can also be achieved by not dividing the channels at equal intervals, but setting the energy region including the energy peaks of the required elements as several channels and operating them as a plurality of single-channel analyzers. .

1 X-ray irradiation unit
2 X-ray detector
3 Sample transfer unit
4 Primary X-ray adjustment means
5 analyzer
6 survey location
7 data processing unit
X1 Primary X-ray
X2 Secondary X-ray
D Sample transfer direction

Claims (8)

An X-ray source capable of irradiating X-rays to the sample;
an X-ray detector for detecting secondary X-rays generated from the sample;
a sample transport unit for transporting the sample; and
an analyzer that discriminates the signal output from the X-ray detector for each energy, counts the number of incidents for each energy, and obtains a spectrum as an X-ray intensity;
It is characterized in that it is determined whether the sample moving in the sample transport unit passes through the X-ray irradiation position from the secondary X-ray intensity of the energy of a specific element of the spectrum obtained by the analyzer and a set threshold value of the X-ray intensity. X-ray analysis device. The method according to claim 1,
X-ray analysis apparatus, characterized in that the data processing unit compares the X-ray intensity of the energy of the specific element of the sample with the threshold value of the set X-ray intensity to determine whether the sample is at the X-ray irradiation position . The method according to claim 1,
X-ray, characterized in that the data processing unit determines whether the sample is in the X-ray irradiation unit by comparing the X-ray intensity of the energy of a specific element of the surface material of the sample carrying unit with the threshold value of the set X-ray intensity analysis device. The method according to claim 1,
X-ray analysis apparatus, characterized in that the data processing unit compares the X-ray intensity of the scattered ray of the primary X-ray with a threshold value of the set X-ray intensity to determine whether the sample is in the X-ray irradiation unit. The method according to claim 1,
X-ray analysis, characterized in that the analyzer continuously acquires the X-ray intensity of the secondary X-ray detected by the X-ray detector at a time interval shorter than the time required for the sample to pass through the X-ray irradiation position. Device. The method according to claim 1,
The X-ray analyzer according to claim 1, wherein the data processing unit is capable of selecting a spectrum at a point in time when the sample is in the X-ray irradiation unit from a characteristic amount of a spectrum obtained by machine learning. 7. The method according to any one of claims 1 to 6,
X-ray spectrum is an X-ray analysis device, characterized in that it is based on a histogram of X-ray coefficients divided by equal intervals in a range of continuous energy or wavelength. 6. The method according to any one of claims 1 to 5,
An X-ray spectrum is a coefficient of a specific energy range, or a combination of a plurality of X-ray analyzers.

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