JP4881307B2 - X-ray fluorescence analysis method - Google Patents

Description

  The present invention relates to an X-ray analysis apparatus and method for analyzing surface information of a sample.

  Lead-free mounting boards are being promoted as environmental measures for semiconductors and electronic components. In the field of the quality control concerned, there is a demand to measure a very thin plating film thickness of a minute part on a substrate (a metal film measurement of several to several tens of nanometers) and to measure a trace amount of lead in lead-free solder. . Depending on the analysis target, analysis of a minute part of φ0.1 mm or less may be required.

  An X-ray fluorescence analyzer is an analyzer that can obtain detailed information on the constituent elements of a sample. In this analysis technique, constituent elements of a sample can be analyzed by measuring the energy of fluorescent X-rays generated by irradiating the sample surface with X-rays.

Since many X-ray generation sources generate an X-ray beam having a relatively large focal point, it is necessary to keep the beam irradiation diameter narrow in order to analyze the minute part as described above. There is an example in which an X-ray focusing mirror, a capillary lens, or the like is used as a condensing lens in order to keep the intensity of the X-ray beam strong while suppressing the irradiation diameter in a narrow range (see, for example, Patent Document 1).
Special table 2002-521676

  Conventionally, a collimator has been used as means for narrowing the range of X-rays emitted from an X-ray generation source to an analysis region. Furthermore, the analysis region can be changed by switching a plurality of collimators. However, the irradiation diameter of the condensed X-ray beam using the condensing lens is fixed to a certain fixed value peculiar to the condensing lens. In addition, since the irradiation diameter of the focused X-ray beam itself is focused below the pinhole diameter of the conventional collimator, the analysis region cannot be changed by switching the collimator.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an apparatus and method capable of changing and expanding an analysis region in analysis using a focused X-ray beam.

In order to solve the above problem, a fluorescent X-ray analysis method of the present onset Ming, the irradiation spot of the X-ray beam was focused X-rays of the X-ray generation hands stage or found on a sample, generated from the sample surface per the detecting fluorescent X-rays, there is the targeted scan a wider analytical range than the irradiation spot of the area of the X-ray beam by driving the sample stage for mounting a sample, the actual scanning region The fluorescent X-ray data detected in consideration of the difference in the analysis region is analyzed .

The fluorescent X-ray analysis how the present invention is relates to a drive method of the sample stage can be considered various methods the analytical conditions. When a rectangular region is designated, analysis of the designated region is realized by driving the stage while irradiating the X-ray so that the X-ray irradiation spot fills the region in the X and Y axis directions on the sample. Furthermore, when a circular region is designated, X-rays uniformly focused on the designated region can be irradiated by driving the stage while irradiating X-rays concentrically or spirally on the sample. When X-rays are irradiated outside the designated area for driving the stage, only necessary data can be obtained by discarding the data obtained outside the designated area.

By driving the sample stage, not only it allows the analysis of areas on the irradiation diameter or condensing X-ray beam, by setting the driving dynamic method and the analysis region, X-ray irradiation dose in the analysis region is uniform Ki de be made to be in, the setting of a region to be analyzed with scanning region, to allow X-ray fluorescence analysis of the analysis region of arbitrary shape.

  The present invention will be specifically described below with reference to the drawings. FIG. 1 is a system configuration diagram showing an embodiment of the present invention. The X-ray 2 emitted from the X-ray generation source 1 passes through the condenser lens 3 and is condensed and irradiated on the sample 4. The fluorescent X-rays or photoelectrons emitted by irradiating the sample 4 with the X-ray 2 are detected by the particle detector 7, and the data measured by the counting circuit 9 is input to the control device 11 as acquired data. A sample stage 5 is provided below the X-ray generation source 1 and the condenser lens 3. The stage control unit 6 drives the sample stage 5 with a signal from the control device 11. In order to observe the sample surface, a camera 8 and an imaging circuit 10 are installed. Information on the control device is displayed on the monitor 12. Further, the constituent element ratio of the sample 4 or the thickness of the thin film on the surface of the sample 4 is calculated by the control device 11 based on the acquired data and displayed on the monitor 12.

  Now, the condensed X-ray beam that has passed through the condenser lens 3 is narrowed down to the irradiation diameter unique to the condenser lens. The sample 4 on the sample stage 5 is irradiated with X-rays 2 with the irradiation diameter. The irradiation position of the X-ray 2 on the sample can be moved by driving the sample stage 5 during the X-ray 2 irradiation. The movement amount of the X-ray 2 is obtained from the analysis region, and the movement speed is calculated by the control device 11 based on the movement amount and the analysis time. By inputting the obtained movement amount and movement speed of the X-ray 2 to the stage control unit 6, the stage drive is controlled and analyzed.

  2A to 2D are diagrams showing a method for driving the sample stage in the present invention, in which the sample 4 on the sample stage 5 is viewed from the upper surface (X-ray source side). FIG. 2A shows a state before the stage is driven, and the X-ray irradiation spot 14 is at the position of the point P in the analysis region 13. There are a plurality of types of definition of the X-ray irradiation spot diameter, but here they are defined as follows. All the intensities in one direction (Y direction) are integrated so that the intensity distribution of irradiated X-rays distributed two-dimensionally in the XY plane can be handled in one dimension (for example, the X direction). In the one-dimensional intensity distribution after integration, a width (half-value width) that is half the maximum intensity is defined as an irradiation spot diameter.

  Here, for example, it is assumed that an analysis range of a rectangular area A having a size of α in the X direction and β in the Y direction is input. Then, in the state irradiated with X-rays, the sample stage 5 is moved by the magnitude of α in the direction of the arrow shown in FIG. 2A, and the X-ray irradiation spot 14 is positioned at Q in FIG. 2B. Move to. Thereby, the analysis between the points P and Q on the sample 4 can be performed. After the X-ray irradiation spot 14 has moved to the position Q in the analysis region 13 in FIG. 2B, the sample stage 5 is moved in the direction of the arrow shown in FIG. Thereby, the X-ray irradiation spot 14 moves to the position R in the analysis region 13 of FIG. After the X-ray irradiation spot 14 has moved to the position R in the analysis region 13 in FIG. 2C, the sample stage 5 is moved in the direction of the arrow shown in FIG.

  As described above, after moving the sample stage 5 by the magnitude of α in the X-axis direction, the sample stage 5 is repeatedly moved by the magnitude of γ in the Y-axis direction. As this γ, an X-ray irradiation spot diameter or a shorter length is set so that a region with an extremely small amount of X-ray irradiation does not occur. As a result, the X-ray irradiation spot 14 moves so as to fill the region A. When the X-ray irradiation spot 14 moves to the position S in the analysis region 13 in FIG. 2D, the amount of movement of the sample stage 5 in the Y-axis direction becomes β, and the X-ray 2 is in the region A. It was irradiated.

  In addition, when moving from FIG. 2B to FIG. 2C, a method of moving while irradiating X-rays and discarding data acquired during movement, and stopping X-ray irradiation during movement. Thus, there are a method of not acquiring data and a method of storing data acquired during movement without distinction. The range A can be analyzed by these driving methods and analysis methods.

  Regarding the above-described rectangular stage driving, driving methods as shown in FIGS. First, the movement of the X-ray irradiation position in the driving method of FIGS. 2A to 2D is indicated by an arrow in FIG. The X-ray irradiation spot 14 on the sample 4 moves so as to trace the designated area in the X direction and the Y direction in the area A. At this time, since the X-ray is moved while being irradiated, a difference in X-ray irradiation time is produced at the corner of the region where the stage drive direction changes. In order to reduce the difference, a driving method as shown in FIG. In FIG. 3B, folding is performed outside the area. Thereby, the time for which the sample is irradiated with X-rays can be made substantially constant. At this time, the data acquired outside the area is discarded. In FIGS. 3A and 3B, the stage is driven based on the X direction, but the Y direction may be used as a reference. Furthermore, after driving with reference to the X direction as shown in FIG. 3C, driving may be performed with reference to the Y direction. If the method of FIG.3 (c) is used, X-ray will be irradiated to the sample 4 more uniformly.

  In addition to the rectangular area, a circular area is also conceivable as the area specifying method. With respect to stage driving when a circular analysis region is designated, driving methods as shown in FIGS. 4A to 4C are conceivable. Here, for example, it is assumed that the analysis range of the circular region B having the diameter δ is input. In order to realize the analysis of the circular area B by driving the rectangular stage, a driving method as shown in FIG. The X-ray irradiation spot 14 on the sample 4 moves in the X direction and the Y direction so that the region B fills a square region with one side circumscribing the circular region B having a size of δ. Since the designated area is circular, when square driving is performed, the acquired data in the dotted line portion in FIG. In a circular region, data can be acquired in a shorter time than in FIG. 4A by driving concentrically as shown in FIG. Further, since the sample can be irradiated with X-rays while keeping the stage driving speed constant by driving the stage spirally as shown in FIG. 4C, the sample 4 is uniformly irradiated with X-rays. It will be.

  In addition, as shown in FIG. 5, a driving method in which stage driving and analysis are performed discretely within a region is also conceivable. When the analysis area C is designated, a plurality of spot centers 15 are taken in the area, and the X-ray irradiation spot 14 is aligned with each spot center to acquire data. Assuming that the interval between the centers of the spots is ε, data is acquired after moving the X-ray irradiation spot 14 by ε in the X and Y directions, and the region C is analyzed by covering all the spot centers. Also, when moving to each spot center position, a method of moving while irradiating X-rays and discarding data acquired during movement, and a method of not acquiring data by stopping X-ray irradiation during movement A method of storing data acquired during movement without distinguishing it from data acquired at the center of the spot can be considered.

  In order to shorten the time until the analysis result is displayed, a method of thinning the stage drive may be considered. When the analysis region is designated, X-rays are irradiated while the stage drive in the Y direction is thinned by ζ as shown in FIG. In other words, the X-direction linear irradiation area adjacent to the X-direction linear irradiation area irradiated with the X-rays by the stage that is continuously driven is set to an interval longer than the diameter of the X-ray irradiation spot. Release. By the above driving method, it is possible to shorten the data acquisition time and the time until the analysis result is displayed as compared with the method of driving the entire analysis region densely. At this time, there are a region on the sample that is irradiated with X-rays, such as a region surrounded by a dotted line in FIG. 6B, and a region that is not irradiated with X-rays other than the region surrounded by a dotted line. As incomplete. In order to obtain a more complete analysis result, X-rays can be irradiated on the analysis area on average by driving the stage so as to fill in the thinned portion as shown in FIG. .

  For example, the above driving method can be effectively utilized when the designated analysis conditions are in a wide area. If the analysis is performed while the entire analysis area is driven densely, it takes a long time to complete the data acquisition, and it takes a long time to display the analysis result. As described above, since the display during the analysis becomes close to the average value of the entire analysis area by thinning driving, the prospect of the analysis result can be obtained quickly.

  In addition, it is effective to use thinning driving when measuring a wide area roughly, and driving densely when measuring a narrow area without omission.

  With the above driving method and analysis method, it is possible to provide an apparatus capable of changing the analysis region in the analysis using the condensed X-ray beam.

  In an X-ray analyzer that analyzes the surface information of a sample, even in an X-ray analyzer that uses a focused X-ray beam for X-ray analysis of a minute part, an analysis of a region wider than the irradiation diameter of the focused X-ray beam Can be done.

It is an apparatus block diagram which shows the Example of this invention. It is a figure which shows the example of the stage drive of this invention. It is a figure which shows the 1st example of a movement of the X-ray irradiation spot in this invention. It is a figure which shows the 2nd example of a movement of the X-ray irradiation spot in this invention. It is a figure which shows the 3rd example of a movement of the X-ray irradiation spot in this invention. It is a figure which shows the 4th example of a movement of the X-ray irradiation spot in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray generation source 2 X-ray 3 Condensing lens 4 Sample 5 Sample stage 6 Stage control part 7 Particle detector 8 Camera 9 Count circuit 10 Imaging circuit 11 Control apparatus 12 Monitor 13 Analysis area 14 X-ray irradiation spot 15 Spot center

Claims (4)

The X-ray irradiation spot of the X-ray beam formed when the surface of the sample to be measured is irradiated with the X-ray beam obtained by condensing the X-rays from the X-ray source scans the analysis region of the sample In the fluorescent X-ray analysis method for detecting fluorescent X-rays generated from the sample at that time,
Inputting an analysis region on the sample that is wider than a region of the X-ray irradiation spot;
Inputting a scanning region including the analysis region, which is scanned by the X-ray irradiation spot;
Controlling the driving of the sample stage on which the sample is placed so that the X-ray irradiation spot scans the scanning region;
Detecting the fluorescent X-rays obtained by irradiating the X-ray beam by scanning the X-ray irradiation spot and acquiring integrated data;
Subtracting and discarding fluorescent X-ray data obtained from regions other than the analysis region from the detection data of fluorescent X-rays in the scanning region;
A fluorescent X-ray analysis method comprising: Controlling the driving of the sample stage,
The fluorescent X-ray analysis method according to claim 1, wherein the X-ray irradiation spot is controlled so as to draw a rectangular orbit by alternately repeating movement in the X-axis direction and the Y-axis direction on the sample surface . Controlling the driving of the sample stage,
The fluorescent X-ray analysis method according to claim 1, wherein the X-ray irradiation spot is controlled to move concentrically or spirally on the sample surface . Controlling the driving of the sample stage,
2. The fluorescence according to claim 1, wherein a plurality of detection positions for detecting the fluorescent X-rays are discretely set in the analysis region, and the X-ray irradiation spot is controlled to move discretely between the positions. X-ray analysis method .

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