JP2002328102A - Scanning x-ray microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a scanning speed for a scanning X-ray microscope to provide a means capable of shortening a measuring time. SOLUTION: This scanning X-ray microscope 100 is provided with an X-ray generator 101, an X-ray converging element 102 for converging an X-ray 10 generated from the X-ray generator 101 on a sample S, an oscillation mechanism 103 for oscillating integrally the X-ray generator 101 and the X-ray converging element 102, a sample stage 104 for mounting the sample S, a slide mechanism 105 for slide-moving the sample stage 104, X-ray measuring instruments 106, 107 for detecting X-rays 10A, 10B from the sample S, and an X-ray measurement signal imaging device 108 for controlling operations of the oscillation mechanism 103 and the slide mechanism 105 and for conducting image processing based on measured values measured by the X-ray measuring instruments 106, 107.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray microscope for performing sample analysis using X-rays as a probe, for example, transmission X-ray analysis and fluorescent X-ray analysis.

[0002]

2. Description of the Related Art A scanning X-ray microscope can non-destructively analyze the internal structure and the like of a sample by scanning an X-ray on a measurement area of the sample and detecting transmitted X-rays or fluorescent X-rays from the sample. Things. FIG. 6 is a schematic diagram showing the configuration of a conventional scanning X-ray microscope.
Is an X-ray tube 2 for generating X-rays, an X-ray guide tube 3 for irradiating the sample S with X-rays 2A emitted from the X-ray tube 2, and a two-dimensional scanning with the sample S placed thereon. Possible sample stage 4, transmitted X-ray detector 5 for detecting X-rays 2B transmitted through the sample, fluorescent X-ray detector 6 for detecting fluorescent X-rays 2C emitted from sample S, and scanning of sample stage 4 A computer 7 for controlling and performing image processing based on the measurement values of the transmitted X-ray detector 5 or the fluorescent X-ray detector 6.

According to the conventional scanning X-ray microscope 1,
The measurement area of the sample S is input to the computer 7, the scanning of the sample stage 4 is controlled based on the input information, the X-ray 2 is scanned over the measurement area of the sample S, and the transmission of the measurement area at each scan coordinate is performed. A two-dimensional image of the measurement area is created based on the measurement value of the X-ray detector 5 or the fluorescent X-ray detector 6, and displayed on a display or the like (not shown).

[0004]

However, in the conventional scanning X-ray microscope 1, since the brightness of the X-ray 2A applied to the sample S is low, it is necessary to reduce the influence of noise and the like to obtain an image with high contrast. , The measurement area of the sample S is repeatedly scanned with the X-rays 2A, and the transmission X-ray detector 5 for each scan is scanned.
Alternatively, a method of accumulating and storing the measurement values of the fluorescent X-ray detector 6 in the computer 7 and increasing the S / N by computer operation is adopted.

[0005] On the other hand, the scanning of the sample stage 4 is performed in two axial directions, and it is necessary to perform scanning with an accuracy of micrometer units in most cases. Therefore, the scanning speed of the sample stage 4 is limited in a known scanning mechanism. Accordingly, when the X-ray 2A is scanned a plurality of times on the measurement area, the scan time per scan is long due to the limit of the scanning speed of the sample stage 4, and as a result, the measurement time is prolonged. It took several hours to analyze.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a means for shortening the measurement time by improving the scanning speed of a scanning X-ray microscope.

[0007]

According to a first aspect of the present invention, there is provided a scanning X-ray microscope, comprising: an X-ray source; an X-ray generated from the X-ray source; An X-ray focusing element for focusing, a sample stage on which the sample is placed, an X-ray detector for detecting X-rays from the sample, and a control operation unit for imaging the detected X-rays. A scanning mechanism for integrally swinging the X-ray source and the X-ray focusing element, and sliding the sample stage in a direction orthogonal to the swing direction of the swing mechanism. And a slide mechanism for moving. This gives X
The radiation source and the sample stage are each driven only in one direction to speed up the scanning, and the measurement region of the sample is scanned with the X-ray at a high speed.

According to a second aspect of the present invention, in the scanning X-ray microscope according to the first aspect, the X-ray focusing element narrows down the X-rays generated from the X-ray source to a predetermined size. And an X-ray guide tube for irradiation. The X-ray focusing element is made up of multiple polycapillaries,
The brightness of the X-ray irradiated on the sample is increased.

According to a third aspect of the present invention, in the scanning X-ray microscope according to the first or second aspect, the control operation unit controls the swinging operation of the swinging mechanism by using an X-ray with respect to a vertical axis. As the angle of the optical axis becomes larger, the swing speed becomes slower, so that the incident X-ray dose per unit area of the sample is controlled to be constant. Thus, the non-linear response on the sample due to the swing scanning is converted into a rectangular coordinate system by an appropriate algorithm.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A scanning X-ray microscope 100 according to an embodiment of the present invention will be specifically described below with reference to the drawings. As shown in FIG. 1, the main scanning X-ray microscope 100
Are an X-ray generator (X-ray source) 101 and an X-ray generator 101
An X-ray condensing element 102 for converging the X-rays 10 generated from the laser beam onto the sample S, a swing mechanism 103 for integrally shaking the X-ray generator 101 and the X-ray condensing element 102, and a sample S Stage 104 on which a sample is placed, and sample stage 104
Mechanism 105 for detecting the X-rays 10A and 10B from the sample S, X-ray measuring devices (X-ray detectors) 106 and 107, and the swing mechanism 103 and the operation of the slide mechanism 105. X-ray measurement device 1
An X-ray measurement signal imaging device (control operation unit) 108 for performing image processing based on the measurement values 06 and 107. If necessary, an X-ray shutter or the like may be provided on the optical axis between the X-ray generator 101 and the sample S as a matter of course.

The X-ray generator 101 is, as shown in FIG.
The electron flow emitted from the filament 11 is
Equipped with an X-ray source 13 for generating X-rays by colliding with
The X-ray tube 14 has a structure in which electricity is supplied to the X-ray tube 14 from a high-voltage stabilized power supply (not shown). The X-rays 10 generated in the X-ray tube 14 pass through the beryllium window 15 and enter the entrance of the X-ray condenser 102.

As shown in FIG. 3, the X-ray condensing element 102 has a plurality of X-ray guide tubes 21 made of a hollow glass tube inside a generally conical casing 20 whose diameter is reduced toward the distal end. It is a so-called polycapillary inserted, and irradiates the sample S with the X-rays 10 incident from the entrance 21a narrowed down to a predetermined size. The X-ray guide tube 21 is also reduced in diameter toward the distal end side, and as shown in the figure, the X-rays 10 incident on the X-ray guide tube 21 are predetermined while being totally reflected by the inner wall of the X-ray guide tube 21. And is emitted from the emission port 21b.
As a result, X radially generated from X-ray generator 101
The line 10 is focused on a spot of a predetermined size, for example, a micro beam having a spot diameter of about 30 μm, and is irradiated on the sample S.

The X-ray generator 101 and the X-ray focusing element 10
Reference numeral 2 indicates that the swing mechanism 103 swings integrally. That is, in FIG. 1, the X-ray generator 101 and the X-ray condensing element 102 are swung in the front and back directions of the drawing. FIG. 4 shows the configuration of the swing mechanism 103, but the swing mechanism of the present invention is not limited to this, and it is needless to say that the swing mechanism can be achieved by other configurations.

FIG. 4 shows the structure of the swing mechanism 103 as viewed from the viewpoint E in FIG. 1. As shown in FIG.
The X-ray generator 101 is suspended from a top surface of a frame 30 via a thin steel plate 31 which can be freely bent, and a ball screw receiver 31 is fixed to a part of the lower surface. The ball screw receiver 31 is screwed with a ball screw 32 which is rotatably provided on the frame 30. The ball screw 32 is connected to an actuator 33 such as a motor and rotates, and the actuator 33 is controlled by the X-ray measurement signal imaging device 108. Due to the rotation of the ball screw 32, the ball screw receiving portion 31 is moved in the horizontal direction in the figure, and the X-ray generator 101 is swung.
The X-ray focusing element 102 fixed to 1 also swings. Thus, the X-rays 10 generated from the X-ray generator 101 are scanned in one direction.

The sample stage 104 is a flat base on which the sample S can be fixed, and is disposed below the X-ray focusing element 102. The slide mechanism 10 is mounted on the sample stage 104.
X-ray generator 1 provided by the swing mechanism 103
01 and the X-ray condensing element 102 are slidable in a direction orthogonal to the swing direction, that is, in the left-right direction in FIG. The slide mechanism 105 has a well-known configuration such as a one-axis actuator using a servomotor and a ball screw, and is controlled by the X-ray measurement signal imaging device 108. Thus, the sample S is scanned in a direction orthogonal to the scanning direction of the X-rays 10.

The X-ray measuring device 106 includes the sample stage 10
4, the transmitted X-rays 10 transmitted through the sample S
A is measured, while the X-ray measurement device 107
Is provided at a plurality of positions above and below the sample stage 104 to measure the fluorescent X-rays 10B generated from the sample S. It is possible to use well-known X-ray detection means such as a proportional counter or a scintillator. it can. Further, the X-ray measurement signal imaging device 108 controls the operations of the swing mechanism 103 and the slide mechanism 105, and
A two-dimensional image is created based on the measurement values of 06 and 107,
Display on a display or the like.

The operation of the scanning X-ray microscope 100 will be described below. First, a sample S to be measured, such as an electronic substrate, is fixed on the sample stage 104 and pre-scanned, so that a schematic image of the sample S is displayed on a display or the like, and a desired area of the schematic image is clicked with a mouse. Thus, the measurement area of the sample S is input to the X-ray measurement signal imaging device 108. The X-ray measurement signal imaging device 108, based on the input information,
The X-ray 10 and the sample S generated from the X-ray generator 101 are scanned by operating the 03 and the slide mechanism 105, and the measurement area of the sample S is scanned with the X-ray 10.

Hereinafter, the X-ray measurement signal imaging device 108 will be described.
A method of controlling the swing mechanism 103 and the slide mechanism 105 by the following will be described in detail. As shown in FIG. 5, when the swing mechanism 103 swings and scans the optical axis of the X-ray 10 radiated perpendicularly to the sample surface F, the X-ray 10 When the optical axis is rocked, the scan speed per unit time on the sample surface F is higher at the rocking end side than in the vicinity of the rocking center, and the scan speed is not constant over the entire width of the sample surface F. In order to correct this, the X-ray measurement signal imaging device 108 changes the swing operation of the swing mechanism 103 as the angle θ of the optical axis of the X-ray 10 with respect to the vertical axis Y increases. The control is performed so that the angular velocity ω is slowed and the incident X-ray dose per unit area of the sample S is constant.

This control algorithm is derived as follows. As shown in FIG. 5, the distance from the X-ray generator 101 to the sample surface F is r, and the angular velocity at which the optical axis 10 of the X-ray 10 overlaps the vertical axis Y, ie, θ = 0, is ω. ₀ , the swing angle of the optical axis of the X-ray 10 at time Δt ₀ is Δ
Assuming θ ₀ , the following equation holds.

(Equation 1)

On the other hand, assuming that the angular velocity at which the optical axis of the X-ray 10 further swings from the position at which the optical axis swings by the angle θ with respect to the vertical axis Y is ω, the swing angle of the optical axis of the X-ray 10 at time Δt Is Δθ, the following equation holds.

(Equation 2)

Further, the sample surface F based on the swing angles Δθ ₀ and Δθ
Assuming that the upper scan width is Δx ₀ and Δx, the following two equations hold.

(Equation 3)

In order to keep the scan speed constant over the entire width of the sample surface F, the scan width and the scan time need only be equal. First, assuming that Δx ₀ = Δx, the following equations are derived from the above equations 3 and 4. .

(Equation 4)

Further, the following equations are derived from the above equations 1, 2 and 5.

(Equation 5)

Next, assuming that Δt ₀ = Δt and this is a unit time, the following equation is derived from the above equation 6.

(Equation 6) Thus, if the angular velocity ω ₀ when the optical axis of the X-ray 10 is at a position overlapping with the vertical axis Y is given, the angular velocity ω when swinging by the angle θ can be obtained, and based on this coordinate conversion algorithm, By controlling the swing mechanism 103, the X-ray dose applied to the sample S can be kept constant over the entire measurement area width.

The method of detecting the swing angle θ of the optical axis of the X-ray 10 is not particularly limited. For example, a CCD camera for imaging the X-ray generator 101 and the X-ray condensing element 102 is provided. A well-known detection method can be used, such as by image processing, or by providing the swing mechanism 103 with an angle sensor or the like.

When the swing mechanism 103 finishes swinging the measurement area width, the slide mechanism 105 moves the sample stage by one step, and swing is performed again. By performing this over the entire measurement area, the sample S
0 is scanned, X-rays 10s from the sample S are measured by the X-ray measuring devices 106 and 107, and the X-ray measurement signal imaging device 108 maps the measured values at each scan coordinate to create a two-dimensional image. I do.

The X-ray measurement signal imaging device 108
Is, for example, using a general-purpose computer, the swing mechanism 10
3 and the slide mechanism 105 and the image processing are executed by software.
And, dedicated hardware is provided for the slide mechanism 105,
The control may be performed separately from the image processing.

As described above, the scanning type X according to this embodiment is
According to the X-ray microscope 100, the X-ray generator 101 and the X-ray condensing element 102 are swung in one direction, and the sample stage 104 is slid in a direction orthogonal to the swinging direction, so that the X-ray Since 10 is scanned, the structure of the scanning mechanism can be simplified, the scanning speed can be improved, and high-speed scanning of the X-rays 10 can be performed, and the measurement time is greatly reduced.

Further, using the X-ray focusing device 102 as a polycapillary, the X-rays 10 generated from the X-ray generator 101 are narrowed down, emitted to the sample S, and the brightness of the X-rays applied to the sample S is increased. Therefore, the number of scans can be reduced, and the measurement time can be further reduced.

In this embodiment, the transmitted X-rays and the fluorescent X-rays from the sample S are detected. However, by using appropriate detection means, the diffraction X-rays can be used instead or additionally. Naturally, it is also possible to detect rays, scattered X-rays and the like.

[0031]

As described above, according to the scanning X-ray microscope of the present invention, the swing mechanism for integrally swinging the X-ray source and the X-ray focusing element and the sample stage are provided. A slide mechanism that slides in the direction perpendicular to the swing direction of the swing mechanism is provided. The X-ray source and sample stage are each independently scanned in only one direction, so the structure of the scanning mechanism is simplified. In addition, the scanning speed can be increased, and the measurement time can be greatly reduced.

Further, according to the present invention, the X-ray condensing element is configured to irradiate the X-rays generated from the X-ray source to a predetermined size, thereby irradiating the X-rays irradiating the sample. Brightness is increased and the number of scans is reduced. Thereby, the measurement time can be further reduced.

Further, according to the present invention, the rocking operation of the rocking mechanism is controlled such that the rocking speed becomes slower as the angle of the optical axis of the X-ray with respect to the vertical axis becomes larger, so that the rocking speed per unit area of the sample is increased. Is controlled so that the incident X-ray dose is constant.
The non-linear response on the sample due to the oscillating scan is converted into a rectangular coordinate system by an appropriate algorithm. This enables high-speed and high-accuracy X-ray analysis.

[Brief description of the drawings]

FIG. 1 is a scanning X-ray microscope 1 according to an embodiment of the present invention.
It is a schematic diagram which shows the structure of 00.

FIG. 2 is a schematic diagram showing a configuration of an X-ray generator 101.

FIG. 3 is a schematic diagram showing a configuration of an X-ray focusing element 102.

FIG. 4 is a schematic diagram showing a configuration of a swing mechanism 103.

FIG. 5 is a diagram for explaining a method of controlling the swing of the X-ray generator 101 and the X-ray focusing element 102.

FIG. 6 is a schematic diagram showing a configuration of a conventional scanning X-ray microscope 1.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Scanning X-ray microscope 101 X-ray generator (X-ray source) 102 X-ray condensing element 103 Swing mechanism 104 Sample stage 105 Slide mechanism 106, 107 X-ray measurement device (X-ray detector) 108 X-ray measurement signal Imaging device (control calculation unit) 21 X-ray guide tube

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsuhiko Hirai 2-18-16 Namikawa, Oimachi, Kameoka, Kyoto (72) Inventor Yoshinori Hosokawa 1-5-16, Osumigaoka, Kyotanabe, Kyoto (72) Inventor Nishino Shigehiro 2 Garan Density 611 F Term (reference) 2G001 AA01 BA04 BA11 CA01 GA06 HA13 JA02 QA01

Claims (3)

[Claims] An X-ray source, an X-ray condensing element for converging X-rays generated from the X-ray source on a sample, a sample stage on which the sample is mounted, and detecting X-rays from the sample An X-ray detector,
A scanning X-ray microscope comprising a control operation unit for imaging a detected X-ray, an oscillating mechanism for integrally oscillating the X-ray source and the X-ray focusing element, and the sample stage And a slide mechanism for sliding the slide mechanism in a direction orthogonal to the swing direction of the swing mechanism. 2. The X-ray focusing device according to claim 1, wherein the X-ray condensing element has an X-ray guide tube for irradiating X-rays generated from an X-ray source to a predetermined size. Scanning X-ray microscope. 3. The control operation unit controls the swinging operation of the swinging mechanism so that the swinging speed decreases as the angle of the optical axis of the X-ray with respect to the vertical axis increases. The scanning X-ray microscope according to claim 1, wherein the incident X-ray dose is controlled to be constant.