JPH10253554A - Equipment for total reflection fluorescent x-ray analysis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate simultaneous analysis of a plurality of elements in a wide range on the same sample, by providing a plurality of irradiation systems each casting a primary X ray on the surface of the sample and by making the incident angles of the primary X rays on the sample differ from each other. SOLUTION: In a first irradiation system 1, a first X-ray source 12 emits an X ray B1. This ray is made monochromatic and converged by a first spectroscope 14 and a W-L β1 ray B2 thus formed is cast on a sample surface 51 at an incident angle ϕ1. In a second irradiation system 2, at the same time, an Mo-Kα ray B2 is cast on the sample surface 51 at an incident angle ϕ2. The irradiation systems 1 and 2 are both positioned in the same azimuth. When the incident angle on one side is set, therefore, the incident angle on the other side is set automatically and thereby setting of the incident angles is facilitated. Each primary X ray B2 excites atoms of a sample 50, fluorescent X rays B3 inherent in elements are generated and part of them enters an X-ray detector 4 and subjected to spectral analysis in a multiple pulse-height analyzer 5. Since both of the W-L β1 ray and the Mo-Kα ray are used, a plurality of elements in a wide range can be analyzed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a total reflection X-ray fluorescence analyzer for simultaneously analyzing a plurality of elements in the same sample by X-ray fluorescence.

[0002]

2. Description of the Related Art Conventionally, as an element suitable for elemental analysis of a surface layer of a sample, primary X-rays from an X-ray source are irradiated at a small incident angle onto a sample surface to generate fluorescent X-rays generated from the sample. There is known a total reflection X-ray fluorescence spectrometer for analyzing the fluorescence. FIG. 4 shows an example of this total reflection X-ray fluorescence spectrometer.

In FIG. 4, an X-ray B 1 emitted from a target material 41 of an X-ray source 11 travels to a spectral crystal 13. The characteristic X-ray of a predetermined wavelength among the X-rays B1 is the spectral crystal 13
Is diffracted into a single color, and its primary X-ray (diffraction X-ray) B
2 is irradiated onto the surface 51 of the sample 50 such as a silicon wafer on the sample stage 7 at a small incident angle α (for example, about 0.05 ° to 0.20 °). Most of the incident primary X-ray B2 is totally reflected and becomes a reflected light beam B4, and the remaining part excites the sample 50 to generate a fluorescent X-ray B3 unique to the element constituting the sample 50. The fluorescent X-ray B3 is applied to the sample surface 51.
Is incident on the X-ray detector 4 disposed opposite to. The X-ray detector 4 detects the X-ray intensity of the incident fluorescent X-ray B3, and then performs a spectrum analysis by the multiplex height analyzer 5 based on the detection signal a from the X-ray detector 4. .

In this type of total reflection X-ray fluorescence spectrometer, the incident angle α of the primary X-ray B2 to the sample 50 is very small, and the reflected light beam B4 and the scattered X-ray are hardly incident on the X-ray detector 4. .
Therefore, the fluorescent X-ray B3 detected by the X-ray detector 4
Noise is smaller than the output level of
An S / N ratio is obtained, so that the analysis sensitivity is good, and for example, even if a trace amount of impurities is contained, it can be detected.

In the above, for the same sample 50,
When generating fluorescent X-rays B3 unique to a plurality of elements over a wide range, it is necessary to replace the X-ray source 11 and use characteristic X-rays having different wavelengths. , It is necessary to replace the crystal 13.

[0006]

As described above, in the conventional apparatus, when a wide range of a plurality of elements are subjected to fluorescent X-ray analysis for the same sample 50, the irradiation system including the X-ray source 11 and the spectral crystal 13 is exchanged. In addition, there is a problem that the measurement operation is complicated because the measurement must be performed each time.

When the irradiation system is exchanged, the incident angle α to the sample 50 is small and the allowable range is narrow due to the necessity of total reflection.
It is difficult to adjust the position and angle of the sample so as to be within the above-mentioned allowable range, and there is a problem that it takes time to analyze the sample.

SUMMARY OF THE INVENTION An object of the present invention is to provide a total reflection X-ray fluorescence spectrometer capable of solving the above-mentioned problems and facilitating simultaneous analysis of a plurality of elements in a wide range on the same sample.

[0009]

In order to achieve the above object, an X-ray fluorescence spectrometer according to the first aspect of the present invention provides a primary X-ray analyzer on a sample surface.
A plurality of irradiation systems for irradiating a line to cause total reflection on the sample surface are provided, and the angles of incidence of primary X-rays on the sample by the respective irradiation systems are different from each other.

[0010] According to the above configuration, one of the plurality of irradiation systems is used.
Since the angles of incidence of the secondary X-rays on the sample are different from each other, a plurality of different primary X-rays are simultaneously incident on the same sample, whereby a wide range of a plurality of elements can be simultaneously subjected to fluorescent X-ray analysis.

Preferably, each irradiation system has an X-ray source for generating the primary X-rays and a spectroscope for monochromaticizing the primary X-rays and causing the primary X-rays to enter the sample. Therefore, a plurality of different monochromatic primary X-rays can be irradiated to the sample surface.

Preferably, the optical path of the primary X-ray from each irradiation system is located on the same plane orthogonal to the sample surface. Therefore, it is possible to easily set the angle of incidence on the sample surface for a plurality of irradiation systems.

Preferably, at least first and second irradiation systems are provided, both of which have a common X-ray source for generating primary X-rays, and wherein the first irradiation system is provided with the primary X-rays. To monochromatic
A second spectroscope has a first spectroscope for making a line incident on the sample, and a second irradiating system has a second spectroscope for making the primary X-ray monochromatic and causing an M-ray to enter the sample. Therefore, primary X
X-ray fluorescence analysis of a plurality of elements in a wide range can be performed at the same time by simultaneously inputting the monochromatic L-ray and the M-ray. In addition, the measurement accuracy of light elements can be improved.

Preferably, an X different from the common X-ray source
A source and a third spectroscope for monochromaticizing primary X-rays from the different X-ray sources and making the primary X-rays incident on the sample. Accordingly, three different monochromatic primary X-rays are simultaneously incident on the same sample, and a wider range of a plurality of elements can be simultaneously subjected to fluorescent X-ray analysis.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a side view of a total reflection X-ray fluorescence spectrometer according to the first embodiment of the present invention. This device is
A plurality of irradiation systems for simultaneously irradiating a sample 50 such as a silicon wafer with primary X-rays B2 to cause total reflection on the sample surface 51, for example, two first irradiation systems and a second irradiation system 2, An X-ray detector 4 composed of a semiconductor detector (SSD) and a multiplex height analyzer 5 are provided to face the sample surface 51.

The first irradiation system 1 irradiates the sample 50 with 1
First X-ray source 12 for generating X-ray B1 to be the next X-ray B2
And a slit 6 for narrowing the generated X-ray B1,
A first dispersive crystal (spectroscope) 14 for converting the line B1 into a single color and allowing the primary X-ray B2 to be incident on the sample 50;
Further, the second irradiation system 2 includes a second X-ray source 32 that generates an X-ray B1 serving as a primary X-ray B2 that irradiates the sample 50, a slit 6 that narrows the generated X-ray B1, X-ray B1
And a second dispersive crystal 34 for making the primary X-ray B2 incident on the sample 50 by making the sample monochromatic.

In both irradiation systems 1 and 2, primary X-rays B2 simultaneously enter the same irradiation area of the sample 50 from the front of the X-ray analyzer (left side in the figure), that is, from the same direction with respect to the sample 50. And a small incident angle φ1 of the primary X-ray B2 from the first irradiation system 1 to the sample 50, and a small incident angle φ1 of the primary X-ray B2 from the second irradiation system 2 to the sample 50. It is different from the minute incident angle φ2. In this example, in order to easily set the incident angles φ1 and φ2 to the sample 50, the optical path K of the primary X-rays B2 from the irradiation systems 1 and 2 is set.
1 and K2 are located on the same plane orthogonal to the sample surface 51.

The X-ray sources 12 and 32 have different targets from each other and emit different primary X-rays B2. For example, the first X-ray source 12 has a target material 42 of tungsten W, and the second X-ray source 32 has a target material 43 of molybdenum Mo. in this case,
The first spectral crystal 14 diffracts the W-Lβ ₁ line, while the second spectral crystal 34 diffracts the Mo-Kα line. Thus, the sample 50 is irradiated with two different primary X-rays B2 that have been made monochromatic.

The X-ray detector 4 detects the X-ray intensity of the fluorescent X-ray B3 generated from the sample 50.
The detection signal a from the X-ray detector 4 is input, and the spectrum analysis of the fluorescent X-ray B3 incident on the X-ray detector 4 is performed.

As described above, the plurality of irradiation systems 1 and 2 can be arranged such that the respective primary X-rays B2 are simultaneously incident on the sample 50 from the same direction at a small incident angle as described above. In the reflection-type X-ray fluorescence spectrometer, the beam width of the primary X-rays B2 from each of the irradiation systems 1 and 2 incident on the sample 50 is small, and the spectral crystal of one irradiation system obstructs the optical path of the other irradiation system. It is based on the applicant's finding that it can be made as small as possible. Hereinafter, this finding will be described.

In FIG. 1, in order to effectively extract the fluorescent X-rays B3 generated from the sample 50, it is necessary to use the X-ray detector 4 and the sample 50 as close as possible. Usually, the distance from the tip of the X-ray detector 4 to the sample 50 is 1.5 to 2 mm. Due to the relationship between this condition and the size of Si (Li) forming the semiconductor of the X-ray detector 4 of 10 mmφ, the spread of the primary X-ray B2 beam on the sample surface 51 detected by the X-ray detector 4 is reduced. The width is 16 mm.

The critical angle φc in the total reflection phenomenon is represented by φc ≒ √ρ ·, where ρ is the density of the sample and λ is the wavelength of the incident X-ray.
λ, and in this example, the first X-ray source 12 has W-Lβ ₁
Line (energy 9.67 keV, wavelength 1.2817 °)
Is used, and a silicon wafer is used for the sample 50. In this case, the critical angle φc is 0.187 °. Therefore, the incident angle of the primary X-ray B2 actually used as the device with respect to the sample 50 is at most 0.4 °.

When the above incident angle is 0.4 ° and the X-ray detector 4
When the visual field on the sample surface 51 is 16 mm, the beam width of the primary X-ray B2 is 16 sin 0.4 ° = 0.1
1 (mm). That is, the optical path K1 of the first irradiation system 1
Is 0.11 (mm).

Now, the Mo-Kα ray of the second X-ray source 32 (energy 17.44 keV, wavelength 0.7107 °)
Is divided by the second spectral crystal 34 having a large Bragg angle θ such as graphite (2d = 6.708 °), and the Bragg angle θ becomes θ = 6.08 °. At this time, assuming that the beam width is 0.11 mm, the effective second dispersive crystal 34
Is 1.04 mm.

Accordingly, the beam width of the primary X-ray B2 with respect to the sample 50 of the first irradiation system 1 can be reduced to 0.11 mm, and the length of the second spectral crystal 34 can be reduced to 1.04 mm. The second spectral crystal 34 can be arranged so as not to obstruct the optical path K1 of the first irradiation system 1,
Can irradiate the same sample 50 from the same direction at different incident angles.

Next, the operation of the present apparatus will be described with reference to FIG. First, the irradiation systems 1 and 2 are arranged so that each primary X-ray B2 irradiates the sample surface 51 at a small incident angle φ1, φ2 from the same direction with respect to the sample 50. And
In the first irradiation system 1, the primary X-ray source 12
An X-ray B1 to be a line B2 is emitted, and the X-ray B1 is monochromatized and condensed by the first dispersive crystal 14 to form a W-Lβ ₁ line
Is irradiated on the sample surface 51 at an incident angle φ1. At the same time, the second X-ray source 32
An X-ray B1 to be the next X-ray B2 is emitted, monochromatized and condensed by the second spectral crystal 34, and the Mo-Kα ray B2 is irradiated onto the sample surface 51 at an incident angle φ2.

In this case, as described above, the first irradiation system 1
Since the critical angle φc of the W-Lβ ₁ line at 0.18 is 0.18 °, the incident angle φ1 is set to the optimal measurement angle 0.18 ° ÷ 2 ≒ 0.1 ° with respect to the sample 50, and the second irradiation System 2
Is the critical angle φc of the Mo-Kα ray at 0.09 °, the incident angle φ2 is the optimum measurement angle 0.09 ° {2}.
It is set to 0.05 °. The setting of the incident angle is performed by moving the sample stage 7 on which the sample 50 is placed in the vertical direction in FIG. 1 and rotating the sample stage 7 in the R direction about an axis AX orthogonal to the plane of FIG. . At this time, both irradiation systems 1, 2
Are in the same azimuth, setting the incident angle of one irradiation system with respect to the sample 50 automatically sets the incident angle of the other irradiation system, which facilitates setting of the incident angle. In addition, the two irradiation systems 1 and 2 can be made compact.

Thus, the sample 50 is provided with both irradiation systems 1, 2
, Two different primary X-rays B2 monochromatized are simultaneously irradiated. Each primary X-ray B2 excites an atom of the sample 50, and the sample 50 generates an element-specific fluorescent X-ray B3.
A part of the fluorescent X-ray B3 enters the X-ray detector 4 and is subjected to spectrum analysis by the multiplex height analyzer 5. This state is shown in FIG.

[0029] As shown in FIG. 2, Zn by W-Lβ ₁ line
Light elements such as ~ Si can be analyzed, and elements such as W and Au can be analyzed by Mo-Kα rays. W-Lβ ₁
W and Au cannot be excited only by the line, and only Mo-Kα line cannot be used to excite Si, S, C
r cannot be excited sufficiently. In contrast, the device of FIG.
W-Lβ ₁ ray and Mo-K from the first and second irradiation systems 1 and 2
Since both α rays are used, a wide range of multiple elements can be analyzed.

Furthermore, two different W-L? ₁ line and M
By simultaneously irradiating the sample 50 with the primary X-ray B2 of the o-Kα ray, the X-ray intensity of the light elements Si to Zn is improved. For example, assuming that the X-ray intensity in the case of only the W-Lβ ₁ line is 1, the light elements Si to Zn have the W-Lβ ₁ line and the Mo-K
When irradiated simultaneously α-rays, M with W-L? ₁ line
When excited by o-Kα rays, the X-ray intensity becomes 1.5 times. Therefore, the light element excitation efficiency is improved, and the analysis accuracy is improved.

As described above, the present apparatus can easily analyze a wide range of a plurality of elements on the same sample easily, and does not require the exchange of the X-ray source and the spectral crystal unlike the conventional one. It is not necessary to measure twice each time, and a single measurement can analyze a wide range of a plurality of elements. Furthermore, the excitation efficiency of the light element is improved, and the measurement accuracy is improved.

Next, the operation of the second embodiment will be described. In this apparatus, as shown in FIG. 3, the first irradiation system 1 and the second irradiation system 2 are provided with a common X-ray source (first X-ray source) 12. Three irradiation systems 3 are provided. Common X-ray source 1 having tungsten W target material 42
A first irradiation system 1 having a second monochromator 2 has a first spectroscope 12 for monochromaticizing the primary X-ray B1 and causing an L-ray such as a W-Lβ ₁ ray to enter the sample 50, and The irradiation system 2 has a second spectroscope 24 for monochromaticizing the primary X-ray B1 and causing the M-ray such as the W-Mα ₁ ray to enter the sample 50. In this case, a beryllium window (not shown) of the X-ray source 12 needs to be thinned so as not to absorb W-Mα rays. The third irradiation system 3 includes a second X-ray source 32A having a target material 43A of molybdenum Mo, and a primary X-ray B1 from the second X-ray source 32A, which is made monochromatic to obtain a sample 50.
And a third spectroscope 34A that makes the light incident on the third spectroscope.

Each of the irradiation systems 1 to 3 is arranged such that three different primary X-rays B2 are incident on the sample 50 from the front (left side in the figure) of the X-ray analyzer, that is, from the same direction with respect to the sample 50. Primary X-rays B1 arranged by each of the irradiation systems 1 to 3
The incident angles φ1 to φ3 of the sample 50 are different from each other. Also in this case, since the irradiation systems 1 to 3 are all in the same direction, setting of the incident angle with respect to the sample 50 is easy, and downsizing can be achieved.

In each of the irradiation systems 1 to 3, the first X-ray source 12 has the target material 42 of tungsten W and the third X-ray source 32A has the target material 43A of molybdenum Mo. the incident angle φ1 of the sample 50 of the W-L? ₁ line to 0.1 ° is optimum, the incident angle φ3 of Mo-K [alpha line is set to 0.05 ° is optimum. Also,
Since the critical angle φc of the W-Mα ₁ line is 1 °, the incident angle φ2 is set to an optimum value of 1 ° ÷ 2 ≒ 0.5 °.

[0035] By simultaneous irradiation to the sample 50 of the primary X-rays B2 of the illumination system 1 to 3, Zn2 by W-L? ₁ line
Elements such as Si are analyzed, and W, Au
Analyze elements such as W
The -Emuarufa ₁ line, (longer wavelength) lower energy level than Si Na, can be analyzed element such as Al. Accordingly, a wider range of a plurality of elements can be analyzed than in the first embodiment.

[0036]

As described above, according to the present invention, the angles of incidence of primary X-rays on a sample by a plurality of irradiation systems are different from each other. At the same time, and a wide range of elements can be simultaneously subjected to fluorescent X-ray analysis.

[Brief description of the drawings]

FIG. 1 is a side view showing an X-ray fluorescence spectrometer according to a first embodiment of the present invention.

FIG. 2 is an array diagram showing elements that can be subjected to fluorescent X-ray analysis.

FIG. 3 is a side view showing a fluorescent X-ray analyzer according to a second embodiment.

FIG. 4 is a side view showing a conventional fluorescent X-ray analyzer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st irradiation system, 2 ... 2nd irradiation system, 3 ... 3rd irradiation system, 12 ... 1st X-ray source, 32, 32A ... 2nd X-ray source, 14 ... 1st spectroscopy Instruments, 34, 24 ... second spectroscope,
34A: third spectroscope, 50: sample.

Claims (5)

[Claims] An irradiation system for irradiating a sample surface with primary X-rays to cause total reflection on the sample surface, and a fluorescent X-ray from the sample.
A total reflection X-ray fluorescence spectrometer provided with an X-ray detector for detecting X-rays, wherein the plurality of irradiation systems are provided, and the angles of incidence of primary X-rays on the sample by the respective irradiation systems are different from each other. A total reflection X-ray fluorescence analyzer. 2. An irradiation system according to claim 1, wherein each irradiation system comprises: an X-ray source for generating the primary X-ray;
A total reflection X-ray fluorescence spectrometer, comprising: a spectroscope that monochromatizes the next X-ray and makes it incident on the sample. 3. The total reflection X-ray fluorescence spectrometer according to claim 2, wherein the optical path of the primary X-ray from each irradiation system is located on the same plane orthogonal to the sample surface. 4. The method according to claim 1, further comprising at least first and second irradiation systems, both of which have a common X-ray source for generating primary X-rays,
The first irradiation system has a first spectroscope for monochromaticizing the primary X-ray and making the L-ray incident on a sample, and the second irradiation system has the first irradiation system.
A total reflection X-ray fluorescence spectrometer having a second spectroscope for monochromaticizing the next X-ray and making the M-ray incident on the sample. 5. The apparatus according to claim 4, further comprising an X-ray source different from the common X-ray source, and a primary X-ray from the different X-ray source being monochromatic and incident on the sample.
Total reflection X-ray fluorescence spectrometer comprising: