JP2000298107A - Holding device for analytical sample and analytical method for sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holding device for an analytical sample and an analytical method for the sample in an analytical device for the sample which can speedily and certainly distinguish a sample position from detected data by scanning the sample without depending on the mechanical accuracy of the device. SOLUTION: In a holding device for a sample to be analized for an analytical device which holds the sample on a surface of a sample holding substrate 2 that can perform scanning in XY directions through application of a beam thereto and optically detects the sample which is irradiated with the beam, a pattern 13 for distinguishing a sample position in which slits 14 are formed in a sample holding part is formed on the surface of this substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample holding device and a sample analyzing method for analyzing trace impurities contained in a sample. More specifically, the present invention relates to a sample holding device and a sample analysis method in a sample analyzer for irradiating an incident beam such as an excitation X-ray and optically detecting the beam and analyzing the sample based on the detected data.

[0002]

2. Description of the Related Art For pathological analysis in biological fluids or wafer contamination control in a semiconductor manufacturing process, etc.
As a method for non-destructively analyzing elements contained in a sample, a total reflection X-ray fluorescence analysis method is used.

In this total reflection X-ray fluorescence analysis method, for example, a liquid sample is dropped onto the surface of a substrate such as a quartz glass or silicon single crystal wafer, and the sample is subjected to a concentration treatment of evaporating to dryness. Excited X-rays with a high energy level are irradiated under total reflection conditions, and fluorescent X-rays from
Is detected by a semiconductor detector made of Si doped with, and the detection data is analyzed by a computer to analyze the sample.

When performing such total reflection X-ray fluorescence analysis, 1. The position of the sample on the substrate is accurately known in advance; It is necessary that the sample position on the substrate is properly irradiated with the excitation X-rays and that the detector is properly oriented at the sample position. If these conditions are not met, the sensitivity will drop significantly or will not be detected at all.

Conventionally, in order to achieve the above condition 1, for example, JP-A-5-256794 and JP-A-7-239.
Various methods are proposed in, for example, Japanese Patent Publication No. 291/291.

According to the above publication, when a sample liquid is dropped,
Using a jig equipped with an outer tube that holds the sample liquid in a certain area, the sample liquid is dropped inside the jig, and the internal atmosphere is suctioned and decompressed, so that the dried sample of the specified size is placed at the specified position. A sample analysis method for forming is shown.

[0007] In addition, in order to prevent the dropped biological fluid sample from easily moving on the wafer surface or being easily peeled off after being dried, hydrofluoric acid is mixed into the biological fluid sample. It discloses a method of increasing viscosity and sticking property.

[0008]

However, even if a sample is analyzed by satisfying the above-mentioned condition 1 according to the technique described in the above-mentioned publications, the condition 2 cannot be sufficiently dealt with by the prior art.

That is, regarding the alignment of the substrate with respect to the irradiation X-ray source and the detector, it is assumed that the sample is correctly held at the sample position on the substrate depending on the mechanical accuracy of the analyzer, and the substrate is excited by the X-ray. The top was scanned and the detected data from that sample position was analyzed. However, it cannot be determined from the detected data whether or not the detected data is actually the detected data from the sample, and the data analysis is performed with the belief of the mechanical accuracy of the apparatus. Therefore, if the sample position, which depends on the mechanical accuracy, is slightly displaced, for example, a very small amount of the element that actually exists may be erroneously determined as “not detected”, and the reliability of data analysis may be reduced. Is reduced.

In this regard, when the sample has a sufficiently high concentration, the position of the sample can be adjusted with reference to the obtained fluorescent X-ray spectrum intensity. As an analyzer using such an adjustment method, a total reflection X-ray fluorescence analyzer with the function of scanning the sample position and automatically finding the position where the intensity of the detection signal based on the sample becomes maximum has been commercialized. (For example, TREX-610 series of Technos Corporation).

However, this method cannot be applied to a very small amount of an analysis sample (for example, an analysis sample having a low concentration such as whether or not it can be detected only by measuring several hundred to several thousand seconds). This is because the time required for scanning is too long and is not practical.

As another method, a method may be considered in which an element serving as a marker is previously mixed into the sample liquid to be dropped as an identifier and scanning is performed using the element as a mark. However, there is a possibility that other contaminant elements may be mixed. In addition, the background noise in the measurement spectrum of the sample may increase due to the contaminated elements and other contaminants, and the spectrum of the element in the vicinity of the detection limit, which is contained in a very small amount, may be buried in the noise and cannot be detected. .

The present invention has been made in consideration of the above-mentioned prior art, and allows a sample to be quickly scanned from its detection data without mixing an identifier into the sample and without depending on the mechanical accuracy of the apparatus. It is another object of the present invention to provide a sample holding device and a sample analysis method in a sample analyzer that can reliably determine the position of a sample.

[0014]

In order to achieve the above object, according to the present invention, a sample to be analyzed is held on a surface of a sample holding substrate which can be scanned in XY directions by irradiating an incident beam,
A sample holding device in an analyzer that optically detects a sample irradiated with an incident beam, wherein a pattern for sample position determination in which a gap is formed in a holding portion of the sample is formed on the surface of the base. An analysis sample holding device is provided.

According to this configuration, since the sample position determining pattern is formed on the sample holding base (eg, a substrate having a flat surface) and the pattern has a gap, the sample is held in the pattern gap. By scanning the substrate (substrate) along this pattern, the pattern forming portion and the gap where the pattern is not formed are clearly distinguished from each other in the detection data. Therefore, by analyzing the detection data of the gap portion where this pattern is not detected,
The sample can be reliably analyzed based on the detection data.

In a preferred configuration example, the pattern is X
It is formed in a band shape along one direction in the Y direction, and a pattern width of a portion facing each other via the gap is narrower than a gap between the facing patterns.

According to this configuration, since the narrow band-shaped pattern is provided through the gap, by scanning along the band-shaped pattern, the sample held in the gap can be reliably detected.

In a further preferred configuration, the analyzer is a total reflection X-ray fluorescence analyzer.

According to this structure, when the sample holding substrate is irradiated with the incident beam at a low angle close to the horizontal under the condition of total reflection, the irradiation position on the substrate is largely shifted due to a slight displacement. The position of the sample can be accurately scanned by performing the position determination in the pattern by
Particularly remarkable effects can be obtained when applied to such a total reflection X-ray fluorescence spectrometer.

To achieve the above object, the present invention further provides:
In a sample analysis method of holding a sample to be analyzed on a surface of a substrate that can be scanned in the X and Y directions by irradiating an incident beam and optically detecting the sample irradiated by the incident beam, a gap is formed in a holding portion of the sample. The formed sample position determination pattern is formed in advance on the surface of the base, and the pattern is scanned with an incident beam that passes through the gap and is narrowed narrower than the gap, and optically scans from a scanning range where the pattern is not detected. Provided is a sample analysis method, characterized in that a sample is analyzed based on a detection signal.

According to this configuration, by using the sample holding substrate on which the sample position determining pattern according to the present invention is formed, the incident beam narrowed from the gap between the patterns is scanned along the pattern. Based on the detected data, a portion where a pattern is not detected is set as a sample position, data from the sample is determined, and the data is analyzed to analyze the sample.

In a preferred configuration example, the pattern is X
It is formed in a band shape along one direction in the Y direction, and the pattern width of a portion facing through the gap is formed to be narrower than a gap of the gap between the facing patterns, and the incident beam is formed on the band pattern. Scanning is performed in a direction perpendicular to the pattern so that the irradiation position of the incident beam is aligned with the pattern, and then the incident beam is scanned along the pattern direction to pass through the gap.

According to this configuration, a narrow band-shaped pattern is formed on the base, and the incident beam is aligned on the pattern by first scanning in a direction perpendicular to the pattern, and then scanning along the pattern. By doing so, the sample can be analyzed based on the detection data from the gap.

In a further preferred configuration example, this analysis method is applied to a total reflection X-ray fluorescence analysis method.

According to this configuration, as described above, when the sample holding substrate is irradiated with the incident beam at a nearly horizontal low angle under the condition of total reflection, the irradiation position on the substrate becomes large due to slight displacement. Because of the shift, the sample position can be accurately scanned by performing the position determination based on the pattern according to the present invention, and a particularly remarkable effect can be obtained when applied to such a total reflection X-ray fluorescence analysis method.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a total reflection X-ray fluorescence spectrometer as an example to which the present invention is applied.

A sample holding substrate 2 is mounted on a sample stage 1,
The sample 3 to be analyzed is held on the sample holding substrate 2. The sample stage 1 is capable of translational three-axis drive in the XYZ directions and rotational drive in the θ direction by a drive mechanism (not shown). As the sample holding substrate 2, a Si single crystal wafer, S
A substrate having a smooth surface such as an iO ₂ plate, a Ge plate, a polymer plate or a quartz glass plate is used, and is selected according to a sample to be measured. The sample 3 is, for example, a liquid sample, and the substrate 2
After being dropped on the substrate, it is evaporated, dried and solidified and held on the substrate 2.

The substrate 2 mounted on such a sample stage 1
Constitutes a sample holding device, and is set in a vacuum chamber (not shown). The sample held on the substrate 2 is irradiated with an excitation X-ray narrowed through a slit 5 from the excitation X-ray source 4 to the sample 3 at a nearly horizontal low angle. As a result, X-rays that do not contribute to the excitation are totally reflected, and only the fluorescent X-rays from the sample 3 are detected by the semiconductor detector 7. The totally reflected X-rays are detected by the X-ray measuring device 6, the intensity of the irradiated X-rays is monitored, and the angle of the sample stage 1 is set to the condition of total reflection.

The semiconductor detector 7 is made of Si doped with Li, and generates a current when irradiated with fluorescent X-rays. The generated current is amplified by the preamplifier 8 and the linear amplifier 9 and
The signal is converted into a digital signal by the converter 10 and divided by the energy of each wavelength of the fluorescent X-ray by the multi-channel analyzer 11, and the intensity is counted for each divided section. The computer 12 determines the elements contained in the sample by data processing based on the detection data obtained by counting the intensities.

A pattern for discriminating the sample position according to the present invention is formed on the upper surface of the sample holding substrate 2 in the total reflection X-ray fluorescence spectrometer having the above configuration.

FIG. 2 shows an embodiment of this pattern shape. In this embodiment, three rectangular patterns 13 having different shapes are formed on the upper surface of the substrate 2 in parallel in the Y direction via the gaps 14 respectively. These patterns 13
Is formed by applying a solution containing a phosphor or a scatterer on the substrate 2 and patterning the solution, or by roughening or treating the surface of the substrate 2 itself with a chemical solution.

The sample 3 (see FIG. 1) is dropped into the gaps 14 between the patterns 13 and evaporated to dryness, irradiated with excitation X-rays, and scanned in the Y direction, so that the portions where the patterns 13 are not detected are obtained. , That is, the gap 1 where the sample is attached
The sample can be analyzed based on the detection data from No. 4 to analyze the contained elements.

FIG. 3 is a plan view showing another example of the shape of the pattern 13. In this example, strip-shaped patterns 13 elongated in the Y direction are arranged vertically along the Y direction with a gap 14 therebetween. The pattern 13 can be formed by various methods in the same manner as in the example of FIG. 2 described above. In the embodiment, for example, the pattern 13 is formed by applying a solution containing iron (Fe) as a phosphor. The interval between the gaps 14 between the patterns 13 is, for example, 7 to 8 mm. A liquid sample containing a small amount of sulfur (S) is dropped as a sample at the center of the gap 14 where the patterns 13 face each other, and the sample is dried and solidified to form a droplet mark having an outer diameter of about 1 mm or less (not shown). ) Formed.

The substrate 2 holding such a sample is placed on the substrate 2 shown in FIG.
Set in the total reflection X-ray fluorescence analyzer shown in
A direction substantially perpendicular to the line connecting the pattern 13 with the line,
That is, light is incident from a direction (X direction) perpendicular to the longitudinal direction (Y direction) of the belt-shaped pattern 13 at a low angle that satisfies the condition of total reflection.

FIGS. 7A and 7B show a state where the substrate 2 on which such a band-shaped pattern 13 is formed is irradiated with excited X-rays. As shown, the incident X-ray beam 15 is
, And is totally reflected at the irradiation spot 17 and reflected X-ray 1
6 are emitted in the symmetric direction. The fluorescent X-rays generated from the irradiation spot 17 are detected by the semiconductor detector 7 as described above. The state shown in FIG. 7 is a state before adjustment in a direction (Z direction) perpendicular to the upper surface of the substrate 2, and the position of the irradiation spot 17 is shifted from the position of the pattern 13 at the center of the substrate to the left side in the figure. Here, the Fe included in the pattern 13
The position of the irradiation spot 17 is aligned with the pattern 13 as shown in FIG. 8 by finely driving the substrate 2 in the Z direction to adjust the position so that the intensity of the fluorescent X-ray becomes maximum based on the above. As described above, first, the position of the irradiation spot 17 of the incident X-ray beam 15 is scanned in the X direction perpendicular to the pattern 13 by adjusting the position in the Z direction, and the incident X-ray beam 15 is placed on the pattern 13 based on the detection data. Align. In this case, instead of the adjustment method in which the substrate 2 is minutely driven in the Z direction, the substrate 2 is minutely driven directly in the X direction and the incident X-ray beam 15 is scanned in the X direction, and the fluorescent X-ray The irradiation spot 17 may be positioned at a position on the pattern 13 where the intensity of the light beam becomes maximum.

In such an X-direction alignment, it is desirable that the width of the pattern 13 is smaller than the interval of the gap 14. This is because the narrower the width, the more accurate the alignment in the X direction.

With the incident X-ray beam 15 positioned on the pattern 13 in this manner, as shown in FIG. Scan above or below. By scanning the pattern 13 in the Y direction, the sample can be analyzed based on the detection data from the portion where the pattern 13 is not detected, that is, the gap 14 where the sample is attached, to analyze the contained elements. The scanning with the incident X-ray beam 15 is performed in a state where the incident X-ray beam 15 is narrowed down more than the interval of the gap 14 of the pattern 13. This is to reliably detect the position of the gap 14.

FIG. 10A shows detection data when scanning the substrate 2 along the pattern 13 as shown in FIG. The horizontal axis shows the scanning position in the Y direction, and the vertical axis shows the count number corresponding to the intensity of the fluorescent X-ray. As can be seen from the data in the figure, the intensity of the fluorescent X-rays of Fe contained in the pattern makes it possible to clearly distinguish the portion having the pattern from the portion having no pattern. S is also detected at the position of the pattern with an increased intensity in the same manner as Fe, but this is due to the fact that the background of the entire spectrum is raised by Fe, and actually, S is detected. S is not included in the pattern portion.

At the center of the part without the pattern, the fluorescent X of S
A line signal has been obtained. There is a trace of evaporation of the liquid sample in this part. Conventionally, it has been difficult to detect such a minute signal by in-plane scanning. However, in the present invention, Fe contained in the pattern is used as a marker for identification.
A small fluorescent X-ray signal of S can be easily found.

As described above, if the measurement is performed at a portion where a signal based on the pattern does not appear, that is, at a portion of the gap between the patterns, accurate alignment can be performed. Measurement may be performed.

When S is not contained in the sample, it can be confirmed that S is not contained in the sample by measuring the spectrum of the portion having no pattern.

In the above description, a material containing a phosphor is used as the pattern 13. However, instead of such a pattern using a phosphor, for example, the pattern may be formed of a material containing a scatterer, or a substrate may be formed. By treating the surface with a corrosive agent to generate surface roughness and scatter the excited X-rays radiated by the substrate itself, the excited X-
A change in the intensity of the scattered light of the line is detected, and a portion having a pattern and a portion having no pattern can be determined based on the detected change. Also in this case, the intensity of the scattered light was monitored to
A detection intensity curve similar to that of (A) is obtained.

Further, in the above-described embodiment, a droplet trace having a diameter of about 1 mm was used as a sample, and excitation X-rays narrowed down to about 1 mm were used, and the gap between the patterns was set to about 7 to 8 mm. Although the result appears in a very small part of the part without the pattern, the gap between the patterns is narrowed and formed as an interval slightly larger than the beam diameter of the excitation X-ray, so that the detection signal of S is converted to the pattern. It can be expressed in almost the entire non-existing portion, and the setting of the optimum measurement position is uniquely determined.

FIG. 4 shows another example of the shape of the pattern formed on the substrate according to the present invention. This example uses pattern 13
Is a vertically long diamond-shaped pattern shape in which the center is thick and both ends are tapered. With the pattern 13 having such a shape, the same operation and effect as those of the uniform band-shaped pattern in FIG. 3 can be obtained, and the alignment can be easily adjusted due to the wide portion in the center of the pattern.

FIG. 5 shows still another example of the shape of the pattern according to the present invention. In this example, the pattern is used not only as a measure of the position but also as a reference for quantitative detection. In the quantitative measurement of the sample, by appropriately determining the concentration of the element contained in the pattern, and by changing the pattern width with respect to the moving amount in the scanning direction, the amount of the change can be used as a standard for quantification. Such a change in the pattern width can be used as a measure of quantification even if the change is a linear proportional function as in the shape of FIG. 4 described above. However, as shown in FIG. For example, by changing it exponentially, the amount of change with respect to the amount of movement increases, and the range in which quantitative measurement can be performed is widened.

FIG. 10B shows a pattern 1 having the shape shown in FIG.
6 is a graph showing a change in pattern width of No. 3; The horizontal axis X indicates the amount of movement, and the vertical axis Y indicates the change in the pattern width. As shown, the pattern width changes exponentially with respect to the movement amount. By using the pattern 13 having such a shape, quantitative measurement of the sample can be performed using the detected data as a comparison standard.

FIG. 6 shows another example of the shape of the pattern according to the present invention. In this example, a band-shaped pattern 13 is formed by connecting small circular patterns. By forming the pattern as a continuous pattern connected by repetition of a small cycle as described above, it can be used as a guide for fine position determination, and a variation in the pattern forming process can be widened to facilitate manufacturing.

In each of the above embodiments, a method is used in which a pattern is formed on the surface of a substrate such as a wafer in advance, and then the sample is attached to the substrate. You can also. in this case,
For example, a pattern of a phosphor or a scatterer can be printed and formed on a substrate using a stamp-like mold having the pattern shape shown in FIGS.

The present invention is not limited to the total reflection X-ray fluorescence spectrometer, but irradiates other electron beam, visible light or other light as an incident beam instead of the excitation X-ray, and detects the reflected light or scattered light. The present invention can also be applied to an analyzer for performing analysis.

The sample to be analyzed is not limited to a liquid sample, and the present invention can be applied to a powder or a solid.

The substrate for holding the sample is not limited to a wafer-like thin plate, but may be a block-shaped member having a smooth surface or any other member.

[0052]

As described above, according to the present invention, a sample position determining pattern is formed on a sample holding base (for example, a substrate having a flat surface), and a gap is provided in this pattern. Hold the sample in the gap,
By scanning the base (substrate) along this pattern, the pattern forming portion and the gap where no pattern is formed are clearly distinguished from each other in the detection data. Therefore, by analyzing the detection data of the gap portion where this pattern is not detected, the sample can be reliably analyzed based on the detection data.

In this case, the intensity of the fluorescence or the scattered light based on the pattern is sufficiently high, so that the scanning of the sample position can be performed quickly. Further, after the alignment of the sample is completed, no fluorescence or scattered light based on the pattern is detected, so that the pattern does not hinder the measurement even in the case of trace analysis.

As described above, since the positioning is performed based on the signal based on the pattern formed on the sample holding substrate, the positioning accuracy of the apparatus is insufficient or the apparatus does not have a sample position detecting function. Even in this case, the sample can be accurately and quickly aligned.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a total reflection X-ray fluorescence analyzer to which the present invention is applied.

FIG. 2 is a plan view of a substrate having a pattern for identifying a sample position according to the present invention.

FIG. 3 is a plan view of a substrate having another pattern according to the present invention.

FIG. 4 is a plan view of a substrate having another pattern according to the present invention.

FIG. 5 is a plan view of a substrate having still another pattern according to the present invention.

FIG. 6 is a plan view of a substrate having still another pattern according to the present invention.

FIG. 7 is an explanatory diagram of a sample positioning procedure of the present invention;
(A) is a plan view, (B) is a perspective view.

FIG. 8 is an explanatory view of the sample positioning procedure of the present invention following FIG. 7;

FIG. 9 is an explanatory view of the sample positioning procedure of the present invention following FIG. 8, (A) is a plan view, and (B) is a perspective view.

FIGS. 10A and 10B are graphs of pattern detection data and pattern width change of the present invention, respectively.

[Explanation of symbols]

1: sample stage, 2: sample holding substrate, 3: sample, 4: excitation X
Source: 5: slit; 6: X-ray measuring instrument; 7: semiconductor detector; 13: pattern; 14: gap.

Claims (6)

[Claims] 1. A sample holding device in an analyzer for holding a sample to be analyzed on a surface of a sample holding substrate which can be scanned in the X and Y directions by irradiating an incident beam and optically detecting the sample irradiated with the incident beam. An analysis sample holding device, wherein a sample position discrimination pattern in which a gap is formed in the sample holding section is formed on the surface of the base. 2. The method according to claim 1, wherein the pattern is formed in a band shape along one of the XY directions, and a pattern width of a portion facing through the gap is smaller than an interval of the gap between the facing patterns. The analytical sample holding device according to claim 1, wherein: 3. The apparatus according to claim 1, wherein the analyzer is a total reflection X-ray fluorescence analyzer. 4. A sample analysis method comprising: holding a sample to be analyzed on a surface of a substrate scanable in XY directions by irradiating an incident beam; and optically detecting the sample irradiated by the incident beam. A sample position determination pattern in which a gap is formed in the holding unit is formed in advance on the surface of the base, and the pattern is scanned with an incident beam that passes through the gap and is narrowed down from the gap, and the pattern is not detected. A sample analysis method comprising: analyzing a sample based on an optical detection signal from a range. 5. The pattern is formed in a band shape along one of the XY directions, and a pattern width of a portion opposed to each other via the gap is formed to be narrower than a gap between the opposed patterns. Scanning the incident beam in a direction perpendicular to the band-shaped pattern, aligning the irradiation position of the incident beam on the pattern, and then scanning the incident beam along the pattern direction to pass through the gap. 5. The method according to claim 4, wherein
The sample analysis method according to 1. 6. The sample analysis method according to claim 4, wherein the method is applied to a total reflection X-ray fluorescence analysis method.