JPH0643972B2 - Non-destructive measurement method of DUT by X-ray - Google Patents

Description

The present invention relates to a method for analyzing and measuring the composition, thickness and the like of an object to be measured by a nondestructive measuring means utilizing X-rays.

"Prior art" When non-destructively measuring the composition concentration, composition distribution, thickness, etc. of an opaque object by irradiation, γ rays such as isotopes (Ga, Ir, Co) or X rays Using
Irradiates the DUT with radiation emitted from the radiation irradiation system,
The intensity of the transmission line is measured and analyzed by a detection system, but in the case of nondestructive measurement method using isotope, isotope is difficult to obtain, its intensity is weak or too strong, and its half-life is short. It is said that industrialization is difficult due to the reasons described above, and thus the method using white X-rays is widely used.

As the X-ray source at this time, a source targeting W (tungsten) is often used.

Generally, when performing composition analysis of an axisymmetric measured object composed of two constituent elements, two monochromatic X-rays extracted from the X-ray source are irradiated to the measured object to measure their transmitted X-rays. Multilayer division method based on such measurement data,
The composition distribution in one cross section of the object to be measured is obtained by a calculation method such as the Abel transform method.

The X-rays are attenuated by passing through the object to be measured, that is, when X-rays having a certain wavelength pass through a substance having a thickness t and a mass absorption coefficient μ (cm ⁻¹ ), the X-rays The intensity changes from I ₀ to I.

The transmitted X-ray dose I at this time can be expressed by the following equation.

I = I ₀ e ^−μt (eq1) From the above (eq1), the unknown thickness t of the object to be measured is obtained by the following equation.

[Problems to be Solved by the Invention] By the way, when a monochromatic X-ray source is taken out from a white X-ray source, and one cross section of the object to be measured is irradiated and detected by an X-ray detector, many monochromatic X-rays are detected. However, there are problems that the optical system is complicated to obtain the light by diffraction and expensive equipment is required.

Therefore, there is a means for emitting only one X-ray beam from an X-ray source, irradiating the measured object as monochromatic X-rays by diffraction, and scanning the measured object at the time of irradiation. The means is also not applicable when the object to be measured cannot be scanned, such as online measurement.

In view of the above problems, the present invention aims to provide a method capable of easily and highly accurately measuring desired measurement items of an object to be measured and measuring and analyzing the object without scanning the object to be measured.

[Means for Solving Problems] In order to achieve the above object, the present invention irradiates an object to be measured with X-rays emitted from a white X-ray source, and transmits X-rays after passing through the object to be measured. Is detected by an X-ray detector, the detected amount is arithmetically processed, and the physical quantity such as the composition distribution and thickness of the measured object is determined nondestructively. The emitted X-rays are passed through a high-pass filter and a low-pass filter that have a common pass region that is narrow enough to allow the pseudo monochromatic X-rays to pass, and the pseudo monochromatic X-rays are extracted. It is a non-destructive measurement method for an object to be measured by X-rays, which comprises irradiating the object to be measured with monochromatic X-rays.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of measuring and analyzing the composition of an opaque object A having two compositions. As a specific example of these,
In the method for producing an optical porous base material made of SiO ₂ —GeO _2, the case where the physical quantity that is the composition of the base material is analyzed can be mentioned.

In FIG. 1, when the composition of the base material is analyzed, as an X-ray source 1, for example, a white X-ray source having a maximum voltage of 100 kV and a current of 16 mA targeting tungsten is used.

The white X-ray E emitted from the X-ray source 1 is narrowed down by the wide-angle slit plate 2 and is passed through a high-pass filter and a low-pass filter whose transmission regions match each other to generate a pseudo monochromatic X-ray. As the radiation source, the object A to be measured is irradiated with the pseudo monochromatic X-rays. Since the object A at this time has two compositions such as SiO ₂ and GeO ₂ having different mass absorption coefficients, each of them has a predetermined composition. Two kinds of quasi-monochromatic X-rays having relatively low energy E _L and high energy E _H are taken out by the filter, and the object A is irradiated with these E _L and E _H.

For example, the filter F ₁ for E _L is used _first , and then the filter F ₂ for E _H is used. Here, as the filter F ₁ , for example,
Composed of a barium (Ba) filter and a samarium (Sm) filter, the energy of 37 to 45 (center 4
Irradiate the object to be measured with the pseudo monochromatic X-ray of KeV of 1). Further, as the filter F ₂ , for example, a tantalum (Ta) filter and a holmium (Ho) filter are combined to irradiate the DUT with pseudo monochromatic X-rays having an energy of 54 to 67 (center 60) KeV. .

Therefore, the white X-rays E emitted from the X-ray source 1 and narrowed down by the wide-angle slit plate 2 pass through the filter F ₁ set _first to become the pseudo-monochromatic X-rays E _L , which is the object A to be measured.
Is irradiated.

The transmitted X-rays that have passed through the object to be measured A are narrowed down by the multi-slitter 3, and the intensity of the transmitted X-rays is measured by the X-ray detectors 4, 4, 4, ...

The X-ray detector 4 used at this time is, for example, a scintillation counter.

The measurement data thus obtained is analyzed by a computer having a predetermined arithmetic processing function, and the distribution of one composition in one cross section of the base material is obtained.

Next, the pseudo monochromatic X-ray E _H obtained by replacing the filter F 1 in FIG. ₁ with the filter F ₂ and passing the white X-ray E from the X-ray source 1 through the filter F ₂ Similarly, the object A to be measured is irradiated, the transmitted X-rays are measured by the respective X-ray detectors 4, 4, 4, ... Distribution is obtained.

The total measurement time by the X-ray detectors 4, 4, 4 ... Is only a few minutes, and the soot synthesis rate in the above-mentioned base material production is considerably slower than the measurement time, so the analysis means is It could be used sufficiently as a monitor for material production.

Next, an example of measuring the thickness of the object B to be measured as shown in FIG. 2 will be described.

For example, when measuring the thickness of the measured object B made of a Cu plate,
Set a predetermined filter F ₃ at the filter position in Fig. 1,
The object to be measured B is placed between the filter F ₃ and the multi-slitter 3.
To place.

Similar to the above, the following will pass the white X-ray E from the X-ray source 1 through a filter F _{3 including} a high-pass filter and a low-pass filter having a pseudo monochromatic X-ray E _M as a common pass band. The pseudo monochromatic X-ray E _M obtained by irradiating the object to be measured B is measured, and the transmitted X-rays are measured by the X-ray detectors 4, 4, 4 ,. The thickness of the object to be measured B is obtained by analyzing the measurement data.

Here, as the filter F ₃ , for example, a filter made of iridium (Ir) and a filter made of thallium (Tl) are combined and configured, and a pseudo monochromatic X having an energy of 76 to 85 (center 80) KeV is used.
Use lines.

The monochromatic X-ray diffracted by the conventional single crystal is as shown in FIG. 3 (A), but the pseudo monochromatic X-ray in the present invention is in the state shown by the shaded area in FIG. 3 (B). .

The specific configurations of the filters F _{1 to} F ₃ are just examples, and other materials and other energies are appropriately adopted by using the X-ray absorption and energy chart for each material, for example. can do.

[Effects of the Invention] As described above, according to the method of the present invention, when the composition, thickness, etc. of an object to be measured is determined by irradiating the object to be measured with X-rays and measuring the transmitted X-rays, the X-ray The white X-rays emitted from the source are converted into pseudo monochromatic X-rays by a high-pass filter and a low-pass filter whose transmission regions match each other, and the pseudo monochromatic X-rays are applied to the object to be measured. The information about is easily available. Furthermore, since the pseudo monochromatic X-rays are selected from the white X-rays by the high-pass type filter and the low-pass type filter whose transmission areas match each other, the filters having different pass bands are suitable for the physical quantity to be measured. Can be appropriately selected, and therefore, the measurement can be performed with higher accuracy than in the case of using the conventional monochromatic X-ray. Further, the present invention has an excellent effect that it is not necessary to scan the object to be measured as in the conventional case and the equipment is inexpensive.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of the method of the present invention, and FIG.
The figure is an explanatory view showing another example of the object to be measured in the method of the present invention, and FIGS. 3A and 3B are explanatory views of the monochromatic X-ray and the pseudo monochromatic X-ray. 1 ... X-ray source 2 ... Wide-angle slit plate 3 ... Multi-slitter 4 ... X-ray detector A, B ... Object to be measured E ... White X-rays E _H , E _L , E _M・ ・ ・ Pseudo monochromatic X-ray F ₁ , F ₂ , F ₃ …… Filter

Claims (1)

[Claims] 1. An X-ray emitted from a white X-ray source is applied to an object to be measured, the transmitted X-ray after passing through the object to be measured is detected by an X-ray detector, and the detected amount is calculated. In the non-destructive measurement method of the object to be measured, which non-destructively obtains physical quantities such as composition distribution and thickness of the object to be measured, the X-ray emitted from the X-ray source is narrow enough to pass a pseudo monochromatic X-ray. An X-ray characterized in that a pseudo monochromatic X-ray is extracted by passing through a high-pass filter and a low-pass filter having a common pass region, and the extracted pseudo-monochromatic X-ray is applied to an object to be measured. Non-destructive measurement method of the measured object by.