KR102141199B1 - X-ray inspection apparatus - Google Patents

Abstract

An X-ray inspection device capable of suppressing X-ray focus position fluctuation is provided. The X-ray inspection apparatus 1 includes an X-ray tube 12 for irradiating X-rays, a stage 11 having a loading surface 11a on which an inspected object 70 is loaded, and a calibration phantom disposed on the stage 11 ( 80), around the position facing the X-ray tube 12 around the stage 11, the detection surface 15a incident on the X-ray is arranged obliquely with respect to the axial direction of the X-rays irradiated from the X-ray tube 12 It includes an X-ray detector 15. The control unit 50 generates a cross-sectional image of the calibration phantom 80 taken through the X-ray detector 15 to detect the position of the calibration phantom 80 in the cross-section image. And the first process of adjusting the position of the X-ray focus according to the detected position of the calibration phantom 80 and the second process of generating a stereoscopic image of the object 70 photographed by the X-ray detector 15 Perform.

Description

X-ray inspection apparatus

Embodiments of the present invention relates to an X-ray inspection apparatus.

Conventional X-ray inspection apparatus is used in various fields. The X-ray inspection apparatus is an object to be inspected, and is used, for example, to inspect the structure of a semiconductor chip formed on a semiconductor wafer (for example, see Patent Document 1). The X-ray inspection apparatus detects X-rays transmitted through the semiconductor chip with a detector, generates a tomographic image and 3D image data of the semiconductor chip according to the X-ray absorption amount of the inspected object, and inspects the structure of the semiconductor chip.

Patent Document 1; Japanese Patent Publication No. 2017-156328 However, the X-ray tube irradiates electrons to the object to generate X-rays. Many electrons irradiated to the object are converted into heat, and some electrons irradiated are converted into X-rays. In the X-ray tube, the positional displacement of the X-ray focal position caused by the heat generation of the object occurs. The temperature of the X-ray tube also changes during the examination of various objects. As described above, in an X-ray inspection apparatus for inspecting an object having a microstructure such as a semiconductor chip, the object is photographed and inspected at a large magnification. A large magnification can be obtained by bringing the subject under X-ray detector close to the X-ray focus position. Therefore, the deviation of the X-ray focus position is a factor that inhibits the inspection of the inspected object, which affects the magnification of the inspection and the inspection position of the inspected object. A method of detecting the temperature of the X-ray tube with a sensor and correcting the position of the X-ray tube according to the detection result can be considered. However, it is difficult to measure the temperature, and since the correlation between the temperature and the focal position is not clear, it is difficult to correct the position of the X-ray tube at temperature. In addition, when the temperature sensor is installed, the peripheral portion of the X-ray tube is enlarged, so that the object to be inspected approaches the X-ray tube or movement of the object is inhibited.

An object of the present invention is to provide an X-ray inspection apparatus capable of suppressing X-ray focal position fluctuation.

X-ray inspection apparatus according to embodiments of the present invention for achieving the above object, an X-ray tube for irradiating X-rays, a stage having a loading surface on which an inspected object is loaded, a calibration phantom disposed on the stage, the stage The X-ray detector is photographed by the X-ray detector and the X-ray detector arranged around the X-ray tube and positioned at an angle with respect to the axial direction of the X-rays irradiated from the X-ray tube. A first process of generating a cross-sectional image of the calibration phantom, detecting the position of the calibration phantom in the cross-section image, and adjusting the X-ray focus position according to the detected position of the calibration phantom and the X-ray detector It includes a control unit for performing a second process for generating a stereoscopic image of the inspected object photographed by.

In one embodiment of the present invention, the control unit may adjust the X-ray focus position based on the difference between the position and the reference position of the calibration phantom detected in the cross-sectional image.

In one embodiment of the present invention, the controller generates a stereoscopic image of the inspected object by reconstructing a plurality of photographed data obtained by rotating the X-ray detector more than half a turn in the second process, and the first In processing, a smaller number of images of the correction phantom than the photographed data of the inspected object may be acquired, and a cross section of one of the stereoscopic images of the correction phantom generated by reconstructing the acquired photographic data may be defined as the cross-sectional image. have.

In one embodiment of the present invention, the control unit may perform the second processing after performing the first processing.

In one embodiment of the present invention, the control unit may perform the first processing whenever the second processing is performed once.

In one embodiment of the present invention, the control unit may perform the first processing whenever the second processing is performed multiple times.

In one embodiment of the present invention, the X-ray tube is disposed detachably between the stage, a filter for absorbing a specific wavelength among the X-rays is further provided, the control unit to the filter in the first process It can be removed between the X-ray tube and the stage, and the filter can be inserted between the X-ray tube and the stage in the second process.

According to the embodiments of the present invention as described above, it is possible to provide an X-ray inspection apparatus capable of suppressing X-ray focal position fluctuation.

1 is a schematic configuration diagram of an X-ray inspection apparatus.
2 is a schematic perspective view of the shield plate.
3 is a schematic plan view showing a stage, a phantom for correcting an inspected object.
4A is a schematic diagram showing an X-ray tube and an X-ray detector to be inspected.
It is explanatory drawing which shows the change of the focus and the distance of an object by the change of the focal position of an X-ray tube.
5A is a schematic diagram showing an X-ray tube and an X-ray detector to be inspected.
5B is an explanatory diagram showing a change in a transmission position of an inspected object according to a change in a focal position of an X-ray tube.
6 is a schematic perspective view of a calibration phantom.
7 is a schematic perspective view showing a photographing space.
8(a) and 8(b) are explanatory diagrams showing a partial cross section of the photographing space.
9 is an explanatory diagram showing CT values of a photographed section.
It is explanatory drawing which shows the temperature change of an X-ray tube.
It is explanatory drawing which shows the process flow of an X-ray inspection apparatus.
12 is an explanatory diagram showing the processing flow of the comparative example.
13 is an explanatory diagram showing a processing flow of a modified example.
14 is an explanatory diagram of the X-ray spectrum.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention should not be configured as limited to the embodiments described below, but may be embodied in various other forms. The following examples are provided to fully convey the scope of the present invention to those skilled in the art of the present invention rather than to provide the present invention to be completely completed.

In the embodiments of the present invention, when one element is described as being disposed on or connected to another element, the element may be disposed or connected directly on the other element, and other elements are interposed between them. It may be. Alternatively, if one element is described as being disposed or connected directly on the other element, there can be no other element between them. Terms such as first, second, third, etc. may be used to describe various items such as various elements, compositions, regions, layers and/or parts, but the items are not limited by these terms. Would not.

The terminology used in the embodiments of the present invention is used for the purpose of describing specific embodiments only, and is not intended to limit the present invention. In addition, unless otherwise limited, all terms including technical and scientific terms have the same meaning that can be understood by those of ordinary skill in the art. These terms, such as those defined in conventional dictionaries, will be construed to have meanings consistent with their meanings in the context of the description of the invention and the related art, ideally or excessively intuition, unless explicitly defined. It will not be interpreted.

Embodiments of the invention are described with reference to schematic illustrations of ideal embodiments of the invention. Accordingly, changes from the shapes of the illustrations, for example, changes in manufacturing methods and/or tolerances, are those that can be expected sufficiently. Accordingly, the embodiments of the present invention are not limited to specific shapes of regions described as illustrations, but include variations in shapes, and the elements described in the figures are entirely schematic and their shapes Is not intended to describe the exact shape of the elements nor is it intended to limit the scope of the invention.

The first embodiment will be described below.

In addition, the accompanying drawings may enlarge and show components in order to facilitate understanding. The dimensional proportions of the components may differ from those in the actual or other drawings.

1 is a schematic configuration diagram of an X-ray inspection apparatus 1. In Fig. 1, an XYZ Cartesian coordinate system is set, and the operation will be described using the coordinate system. 1 shows the rotational directions (axial direction, circumferential direction) around each axis of the X axis, the Y axis, and the Z axis with arrows. In addition, it is indicated by a solid line in a direction that can be moved for each member.

As shown in FIG. 1, the X-ray inspection apparatus 1 includes an irradiation box (referred to as an "irradiation box") 10, and a control unit 50 as a control unit.

In the irradiation box 10, a stage 11, an X-ray tube 12, a displacement meter 13, an X-ray detector 14, 15, a rotating stage 16, a support arm 17, a shielding unit 20 are provided. Is included.

The control unit 50 includes motor control units 51, 52, 53, and 54, an X-ray tube control unit 55, a displacement measurement unit 56, and an image processing unit 57.

The stage 11 has a loading surface 11a on which the inspected object 70 is loaded, and corresponds to an XY stage which is a material that can be moved horizontally (X-axis direction and Y-axis direction). The stage 11 includes a stage movement mechanism (not shown) having a motor as an actuator, and is moved in a horizontal direction parallel to the mounting surface 11a by the stage movement mechanism. The motor control unit 51 of the control unit 50 controls the motor of the stage 11. Therefore, the X-ray inspection apparatus 1 guides the inspected object 70 loaded on the loading surface 11a to a predetermined inspection target position.

As the material of the stage 11, one having transparency to X-rays can be used. Further, the stage 11 may be movable in the Z-axis direction (vertical direction, vertical direction relative to the loading surface 11a) different from the above-described horizontal direction (X-axis direction and Y-axis direction). Further, the stage 11 may be rotatable in the Z-axis rotation (circumferential direction).

The object 70 to be inspected can be said to be a part of the object loaded on the stage 11, for example. The object is, for example, a wafer on which a semiconductor chip is formed.

As shown in FIG. 3, the wafer as the inspected object 70 is before dicing and includes several semiconductor chips 71. Each semiconductor chip 71 is an inspected object (evaluation sample; 70). The X-ray inspection device 1 is used to inspect the structure of the object 70 to be inspected. In addition, in one inspection process (data collection and reconstruction), only a part of the inspected object 70 (semiconductor chip 71) may be subject to inspection, and one inspected object 70 (one semiconductor chip 71) may be processed multiple times. It might be.

The X-ray tube 12 is disposed above the stage 11. The X-ray tube 12 irradiates X-rays to the inspected object 70. The X-ray tube 12 is not particularly limited, and X-ray inspection is performed. In the X-ray tube control unit 55 of the control unit 50, X-ray generation and stop of the X-ray tube 12 are controlled.

The X-ray tube 12 is connected to the moving mechanism 18. The moving mechanism 18 includes a motor as an actuator. The X-ray tube 12 is supported by the movement mechanism 18 so as to be movable in the Z-axis direction. The motor control unit 53 controls the motor of the moving mechanism 18. The position of the motor control unit 53 in the Z-axis direction of the X-ray tube 12 is changed by the moving mechanism 18.

The displacement meter 13 is used to measure the distance to the surface of the inspected object 70. As the displacement meter 13, for example, a laser displacement meter that measures the distance to the inspected object 70 in a non-contact manner can be used. The displacement measuring unit 56 of the control unit 50 measures the distance to the surface of the inspected object 70 by the displacement meter 13. According to the measurement result by the displacement meter 13, the motor control unit 53 makes the distance between the X-ray tube 12 and the shielding unit 20 a designated distance. The position of the X-ray tube 12 in the X-axis direction is changed according to the magnification. The magnification is expressed as a value obtained by dividing the distance from the X-ray focus (where it occurs) to the X-ray detectors 14 and 15 by the distance from the focus to the inspected object 70.

The X-ray detector 14 is disposed at a position facing the X-ray tube 12 around the stage 11. For example, the X-ray detector 14 is arranged on the surface of the rotating stage 16 located immediately below the stage 11. The X-ray detector 14 is arranged such that its detection surface is perpendicular to the axial direction (Z-axis direction) of the X-rays irradiated from the X-ray tube 12.

The X-ray detector 15 is arranged around the position facing the X-ray tube 12 around the stage 11. For example, the X-ray detector 15 is attached to the second end (tip) of the support arm 17 to which the first end (base end) of the rotating stage 16 is fixed. In addition, the X-ray detector 15 is arranged such that its detection surface is inclined with respect to the axial direction (Z-axis direction) of the X-rays emitted from the X-ray tube 12. As described above, the X-ray detector 15 is arranged such that the X-rays that have passed through the inspected object 70 at an angle are incident perpendicularly to the detection surface.

The rotation stage 16 corresponds to the θ stage so as to be rotatable in the Z-axis rotation (circumferential direction). The rotating stage 16 includes a rotating mechanism (not shown) that includes a motor as an actuator. The motor control unit 54 of the control unit 50 controls the motor of the rotating mechanism to rotate the X-ray detectors 14 and 15 in the circumferential direction.

The X-ray detectors 14 and 15 correspond to, for example, a flat panel detector (FPD). As the detector, for example, an indirect conversion detector and a direct conversion detector can be used. The indirect conversion type detector detects X-rays by converting X-rays to light of different wavelengths in a scintillator and converting the light into electric charges in an array-type photodiode and a charge-coupled device (CCD). The direct conversion type detector converts X-rays into electric charges in a conversion unit (for example, a semiconductor such as amorphous selenium (a-Se)) to detect X-rays.

The X-ray inspection apparatus 1 according to this embodiment includes a shielding unit 20. The shielding device 20 is disposed between the stage 11 and the X-ray tube 12. The shielding unit 20 includes a filter 21 and a shielding plate 22. In addition, the shielding unit 20 is omitted Can be.

The filter 21 absorbs (cuts) a predetermined wavelength included in the X-ray. X-rays include a continuous wavelength range. X-rays may cause deterioration of the properties of the inspected object 70. For example, a semiconductor chip, such as a semiconductor memory, absorbs X-rays so that semiconductor silicon accumulates charge and changes a threshold voltage of a transistor formed inside the semiconductor memory. Therefore, the X-ray inspection apparatus 1 according to the present embodiment absorbs unnecessary X-rays to the inspected object 70 by the filter 21 and suppresses deterioration of characteristics of the inspected object 70 and performs X-ray inspection. can do .

In addition, the filter 21 can be made to include a plurality of filter plates. By preparing a filter plate that absorbs X-rays of different wavelengths and transmitting X-rays to one or more selected filter plates, the wavelength range of the X-rays irradiating the inspected object 70 can be changed.

As shown in Fig. 2, the shield plate 22 may have, for example, a substantially rectangular flat plate shape. In addition, the shape of the shield plate 22 may be arbitrarily changed. The shielding plate 22 includes a collimator 31 and a frame-shaped wall portion 32 erected from the collimator 31. As the material of the shield plate 22, a metal material that X-rays are difficult to pass, for example, lead (Pb) or the like can be used.

The collimator 31 is formed in a substantially rectangular plate shape, and has a plurality of openings 31X. The opening 31X is installed at a desired position to pass X-rays. The X-rays passing through the opening 31X are irradiated to the inspected object 70 shown in FIG. 1. The X-rays penetrate the inspected object 70 and enter the X-ray detectors 14 and 15.

1, 3 and 6, the stage 11 is provided with a calibration phantom 80. 3 and 6, the calibration phantom 80 has a cylindrical shape. A plurality of (five in this embodiment) phantoms 80 for calibration are provided on the stage 11. Further, it is sufficient that at least one or more calibration phantoms 80 are mounted on the stage 11. In this embodiment, the calibration phantom 80 is fixed to the base plate 81 and is fixed to the stage 11 through the base plate 81.

As the material for the calibration phantom 80, for example, a metal such as gold (Au), tungsten (W), aluminum (Al), or an alloy thereof may be used. Further, as a material for the calibration phantom 80, it is sufficient if a projected image by X-rays can be obtained, and materials other than the metals described above can be used.

The size of the calibration phantom 80 is set to a size detectable according to the structure of the inspected object 70 in the resolution (magnification) and height direction (Z direction in FIG. 1) of the X-ray inspection apparatus 1. For example, when the resolution of the X-ray inspection apparatus 1 is 10 µm, the size (cylinder diameter and height) of the phantom 80 for calibration is preferably 10 to 30 µm. If the size is less than the resolution, the calibration phantom 80 cannot be detected. If the size is too large, the crystal precision of the center will deteriorate.

As shown in Fig. 3, a plurality of calibration phantoms 80 are arranged in the X direction and the Y direction. The plurality of calibration phantoms 80 arranged in this way improves the detection accuracy in the height direction (Z direction), and also enables detection of the rotation of the stage 11. In addition, the sizes of the plurality of calibration phantoms 80 need not be the same, and different sizes of calibration phantoms may be mixed and arranged.

As shown in Fig. 4A, the X-ray tube 12 has a target 12T, and generates X-rays 61 by irradiating electrons to the target 12T. The X-ray 61 spreads radially at its occurrence position (focus; F1). The X-ray detector 15 has a plurality of detection elements, and the detection elements are two-dimensionally arranged. The internal state of the inspected object 70 is photographed by the X-ray 61 irradiated to the X-ray detector 15 passing through the inspected object 70. The X-ray 61 extends radially, and a part of the object 70 is photographed by the X-ray detector 15. Therefore, the magnification when measuring the inspected object 70 is determined by the distance Lw from the occurrence position F1 of the X-ray 61 to the inspected object 70 and the occurrence position F1 of the X-ray 61. It corresponds to the ratio Ld/Lw of the distance Ld to the X-ray detector 15.

Of the electrons irradiated to the target 12T, many electrons (for example, 99.9%) are converted into heat, and a small amount of electrons (for example, 0.1%) are converted into X-rays. The target 12T and the X-ray tube 12 thermally expand by the converted heat, and the position of the focal point F1 of the X-rays fluctuates.

4B shows the change of the position (focus F1) of the target 12T by heat. The target 12T indicated by the solid line in FIG. 4B is changed in the vertical direction (Z direction in FIG. 1) in the drawing in relation to the target 12T indicated by a dotted line. This change in position changes the distance Lw between the focal point F1 and the inspected object 70. For example, the X-ray 61a generated in the target 12Ta indicated by a dotted line in Fig. 4B is the inspected object 70. When passing through, the distance between the focal point F1a of the X-ray 61a and the inspected object 70 is Lwa. Similarly, the X-ray 61b generated from the target 12Tb indicated by the solid line is the inspected object 70 ), the distance between the focal point F1b of the X-ray 61b and the object 70 is Lwb. In this case, the distance Lwb is short compared to the distance Lwa. ), the magnification of the data taken by the inspected object 70 greatly changes. The X-rays 61a and 61b shown in Fig. 4B are the centers of the X-rays incident on the X-ray detector 15, as shown in Fig. 4A. The area through which the X-rays 61a and 61b pass in the inspected object 70 is an object to be inspected, so the inspection area and X-rays by the X-ray 61a for the inspected object 70 are shown. The inspection area by (61b) varies depending on the temperature change of the X-ray tube 12.

As shown in FIG. 5A, the X-ray tube 12 is rotated to drive the object 70 and the X-ray detector 15 to pass the X-ray 61a through a desired area of the object 70 to pass through the object 70. Data for one turn of the inspection area is retrieved. When the position of the target 12Tb (the position of the focal point F1) of the X-ray tube 12 changes as shown in FIG. 4B, the area through which the X-ray 61b irradiated from the target 12Tb changes. In this state, data for one turn of the inspected object 70 is acquired. In this case, as shown in Fig. 5B, the position of the region through which the X-ray 61b passes changes. That is, when the position of the target 12Tb (the position of the focal point F1) changes, data of different areas is acquired between one turn.

Therefore, the X-ray inspection apparatus 1 according to the present embodiment adjusts the position of the focal point F1 of the X-ray tube 12 using the calibration phantom 80 shown in FIGS. 1, 3 and 6.

The control unit 50 photographs the calibration phantom 80 and generates a stereoscopic image of the calibration phantom 80. Then, the control unit 50 detects the position shift amount of the generated phantom for correcting the stereoscopic image, and adjusts the position of the focal point F1 of the X-ray tube 12 by the position shift amount.

7 shows a stereoscopic (3D) image 90 obtained with the X-ray detector 15. The image processing unit 57 of the control unit 50 of FIG. 1 obtains a stereoscopic (3D) image 90 of the calibration phantom 80 through the X-ray detector 15. In detail, the motor control unit 54 rotates the X-ray detector 15 in the circumferential direction. The motor controllers 51 and 52 synchronize the rotation of the X-ray detector 15 to control the position of the stage 11 or the like so that the X-rays emitted from the X-ray tube 12 penetrate the calibration phantom 80. The image processing unit 57 obtains a plurality of images obtained by imaging the phantom 80 for calibration from various directions by the X-ray detector 15. Then, the image processing unit 57 performs a reconstruction operation process based on the plurality of images to generate a stereoscopic (3D) image 90 for the phantom 80 for calibration.

Subsequently, the image processing unit 57 of the control unit 50 extracts one XZ plane 91 including the calibration phantom 80 from the created three-dimensional (3D) image 90. The coordinates of the extracted XZ plane 91 are cross-sectional images 91, and are set in advance, for example, by installation of a calibration phantom 80. In addition, coordinates can be obtained using the X-ray detector 14. A vertical (2D) image of the calibration phantom 80 is obtained through the X-ray detector 14 shown in FIG. 1 by irradiating X-rays perpendicular to the calibration phantom 80. This vertical (2D) image represents the XY plane, and the position (Y coordinate) of the phantom 80 for calibration can be obtained. One XZ plane 91 including the phantom 80 for calibration may be extracted according to the Y coordinate.

8(a) and 8(b) show the extracted XZ plane 91. 8(a) and 8(b), an image of the calibration phantom 80 is included at a predetermined height in the XZ plane 91 (in the vertical direction and Z direction in the drawing).

Fig. 8(a) shows a case where the target 12T of the X-ray tube 12 is in a desired position (for example, a portion indicated by a dotted line in Fig. 4B) in the calibration phantom 80. The reference position TR is indicated by a dotted line. Fig. 8(b) shows a case where the target 12T of the X-ray tube 12 corresponding to the phantom 80 for calibration is in a position shifted from a desired position (for example, a part indicated by a solid line in Fig. 4B). In this case, the position of the image of the calibration phantom 80 is deviated from the reference position TR in the vertical direction. The displacement amount at the reference position TR is calculated. The displacement amount with respect to the reference position TR corresponds to the displacement amount of the focal point F1 of the X-ray tube 12.

The displacement amount can be calculated, for example, as a difference between the height of the image center of the calibration phantom 80 included in the XZ plane 91 and the reference position TR. As the center height of the calibration phantom 80, a pixel value of each pixel included in the XZ plane 91, for example, a CT value can be used. The image of the corrected phantom 80 is taken. In the image of the XZ plane 91, each pixel value (CT value) is represented.

FIG. 9 shows the result of integrating the image pixel values of the XZ plane 91 shown in FIG. 8(b) in the X direction. In Figure 9, the horizontal axis is the position in the Z direction of the XZ plane 91, and the vertical axis is the integral value of the CT value. The peak position of the curve L1 obtained by integration represents the center position of the calibration phantom 80 shown in Fig. 8(b). Therefore, the difference between the peak position T80 and the reference position TR of the curve L1 is obtained, and the displacement amount of the focal point F1 of the X-ray tube 12 can be obtained from the difference (height).

10 shows the position change of the focal point F1 of the X-ray tube 12. In Fig. 10, the horizontal axis represents the elapsed time (T) after driving, and the vertical axis represents the variation amount of the focus F1. The position change represents the amount of change based on the position of the focal point F1 at the start of driving, for example. After driving the X-ray inspection apparatus 1, the amount of change is large until a predetermined time, and the position of the focal point F1 changes even after a predetermined time has elapsed.

Here, the processing flow of the X-ray inspection apparatus of the comparative example will be described with reference to FIG. 12. The X-ray inspection apparatus of the comparative example does not have a phantom for calibration.

First, warm-up is performed (step 201). The preheating time is, for example, 1 hour. The stage is then moved to place the object (sample) in the center of the field of view (step 202). The center of view corresponds to the center position of an area (visual time) receiving an X-ray with an X-ray detector. Thereafter, X-rays are irradiated to acquire data for one turn of the object (sample) (daq: data acquisition (sample)) (step 203). Then, the acquired data for one turn reconstructs the data (stereoscopic image) of the inspected object (step 204). Then, the process proceeds to step 202 so that the next test object can be processed. In the process according to this comparative example, the positional difference of the X-ray focus occurs, and the magnification is different depending on the sample, that is, a difference may occur in the stereoscopic image obtained by reconstruction.

Next, the processing flow of the X-ray inspection apparatus 1 according to the present embodiment will be described with reference to FIG. 11.

First, warm-up is performed (step 101). As shown in Fig. 10, the preheating time is set to a time taken for the change to be reduced according to the change of the focus F1, and is, for example, 1 hour.

Subsequently, the stage 11 is moved to place the calibration phantom 80 in the center of the field of view (step 102) (step 102). The center of view is a center position of an area (visual time) receiving X-rays from the X-ray detector 15.

Thereafter, the X-ray is irradiated to rotate the stage 11 and the X-ray detector 15 once to acquire data of the calibration phantom 80 (daq: data acquisition (height phantom)) (step 103). The data corresponds to, for example, X-ray data incident on the X-ray detector 15 by irradiating the X-ray by rotating the stage 11 and the X-ray detector 15 of FIG. 1 for each predetermined angle. The predetermined angle is an angle obtained by dividing a turn by a specific number.

Further, the number of divisions for the calibration phantom 80 can be reduced rather than the number of divisions when acquiring data of the inspected object 70 with respect to the evaluation sample. The number of divisions when acquiring data of the inspected object 70 is set by the structure of the inspected object 70, and is 60 to 240, for example. The calibration phantom 80 only needs to be able to measure its position (height), and it is not necessary to determine the shape in the stereoscopic image. Therefore, when the data of the calibration phantom 80 is acquired, the number of divisions of one turn is smaller than the number of divisions when the data of the inspected object 70 is acquired, so that the time for retrieving data can be reduced. The number of divisions when acquiring the data of the calibration phantom 80 can be, for example, 4 to 16. In addition, it is not necessary to acquire the turn data for the calibration phantom 80, for example, it is possible to obtain data between half a wheel.

The data of the calibration phantom 80 obtained as above is reconstructed to obtain stereoscopic image data (step 104). Then, the position correction data of the focal point F1 of the X-ray tube 12 is calculated from the reconstructed data (calibration of tube position (z-offset)) (step 105). The correction data calculates the center position (height) of the calibration phantom 80, and calculates the difference (displacement amount) between the center position and the reference position (reference height) of the focus F1. The position correction data of the focal point F1 of the X-ray tube 12 is calculated from this displacement amount. Then, with the calculated correction data, the X-ray tube 12 is moved (step 106). The first process of adjusting the position of the focal point F1 of the X-ray tube 12 is performed by steps 102 to 106.

Subsequently, the stage 11 is moved to place the inspected object 70 in the center of the field of view (step 107).

Thereafter, the X-ray is irradiated to rotate the stage 11 and the X-ray detector 15 once to acquire data of the object 70 (daq: data acquisition (sample)) (step 108). The data corresponds to X-ray data incident on the X-ray detector 15 by irradiating the X-ray by rotating the stage 11 and the X-ray detector 15 shown in FIG. 1 at predetermined angles, for example. . The predetermined angle is an angle obtained by dividing a 360-degree wheel by a specific number. The number of divisions can be 60 to 4000, for example.

The data of the inspected object 70 obtained as above is reconstructed, and the stereoscopic image data of the inspected object 70 is reconstructed (step 109). In step 107 to step 109, a second process of generating a stereoscopic image of the inspected object 70 is performed. In the above-described comparative example, only the second processing is repeatedly performed.

Thereafter, the process proceeds to step 102. That is, the X-ray inspection apparatus 1 according to the present embodiment uses the calibration phantom 80 whenever the data of one inspected object 70 is acquired, and the position of the focal point F1 of the X-ray tube 12 Adjust it. Such processing can keep the distance Lw between the focal point F1 of the X-ray tube 12 and the inspected object 70 constant.

As described above, according to this embodiment, the following effects can be obtained.

(1) The X-ray inspection apparatus 1 comprises an X-ray tube 12 for irradiating X-rays, a stage 11 having a loading surface 11a on which an inspected object 70 is loaded, and a calibration arranged on the stage 11 Dragon phantom 80 and X-ray detector 15. The X-ray detector 15 is an axis of the X-rays around the stage 11 around the position facing the X-ray tube 12, and the detection surface 15a incident on the X-rays is irradiated from the X-ray tube 12. It is arranged diagonally with respect to the direction. The control unit 50 generates a cross-sectional image 91 of the calibration phantom 80 photographed through the X-ray detector 15, and detects the position of the calibration phantom 80 of the cross-section image 91. And the first process of adjusting the position of the X-ray focus (F1) according to the detected position of the calibration phantom 80, and a third generation of a stereoscopic image of the object 70 photographed by the X-ray detector 15 2 Perform processing.

Therefore, the X-ray inspection apparatus 1 according to the present embodiment can maintain a constant distance Lw between the focal point F1 of the X-ray tube 12 and the inspected object 70, and stably inspect the inspected object ( 70).

(2) The control unit 50 reconstructs a plurality of photographed data obtained by rotating the X-ray detector 15 once, thereby generating a stereoscopic image of the inspected object 70. In addition, the control unit 50 acquires less shooting data of the calibration phantom 80 than the shooting data of the inspected object 70, and reconstructs the acquired shooting data to generate a stereoscopic image of the calibration phantom 80 The cross section of one of (90) is taken as the cross section image (91). Therefore, it is possible to shorten the time for acquiring the data of the calibration phantom 80 and suppress the decrease in the measurement throughput of the inspected object 70.

(3) The control unit 50 can obtain a stereoscopic image of the second processing, that is, the inspected object 70, after adjusting the first processing, that is, the position of the X-ray tube 12 (the position of the focus F1). Accordingly, the position of the focal point F1 with respect to the inspected object 70 may be adjusted to maintain a constant distance Lw between the focal point F1 and the inspected object 70.

(4) The control unit 50 performs the first processing each time the second processing is performed. Accordingly, the position of the focal point F1 with respect to the inspected object 70 can be adjusted to maintain a constant distance Lw between the focal point F1 and the inspected object 70.

(Example of change)

Further, the above embodiment may be implemented in the following manner. The processing in the above embodiment can be appropriately changed.

13 shows the processing flow of the modified example. In this modification, steps 111 to 118 are the same as steps 101 to 108 (see Fig. 11) in the processing flow of the above-described embodiment. The data of the inspected object 70 obtained in step 119 is reconstructed, and stereoscopic image data of the inspected object 70 is obtained (reconstruction). Then, the count value i is counted up (+1) and compared with the count value i and a predetermined number value n (eg, n = 10). Then, if the count value i is the number value n or less (i ≤ n), the process proceeds to step 117. In step 117, the next inspected object 70 is moved to the center of view. Then, data of the inspected object 70 is acquired (step 118), and stereoscopic image data of the inspected object 70 is generated (step 119).

On the other hand, if the count value i is greater than the count value n (i> n), the process proceeds from step 119 to step 112. Then, the processing of steps 112 to 116 is performed, and the position of the focal point F1 of the X-ray tube 12 is adjusted. That is, in the processing flow shown in FIG. 13, the position of the focal point F1 of the X-ray tube 12 is adjusted once each time the data of the inspected object 70 of the number value n is acquired. When the positional change of the focal point F1 of the X-ray tube 12 is small, it is possible to shorten the time due to the adjustment of the X-ray tube 12 by performing subsequent processing.

In addition, the number value n can be changed as appropriate. In addition, the number value n may be changed according to the correction amount (displacement amount) of the X-ray tube 12. For example, when the position change amount is small, the number value n can be increased to further shorten the time required for the adjustment of the X-ray tube 12. On the other hand, when the displacement amount is large, by reducing the number value n, the position of the focal point F1 of the X-ray tube 12 is adjusted and the distance Lw between the X-ray tube 12 and the inspected object 70 is constant. Can be maintained.

When acquiring data of the calibration phantom 80 according to the above embodiment, the filter 21 can be separated, that is, X-rays can be irradiated to the calibration phantom 80 without passing through the filter 21. 14, the X-ray includes a continuous wavelength region. The filter 21 absorbs (cuts) a predetermined wavelength region (a wavelength region lower than the dotted line in FIG. 14) included in the X-ray. Except for the filter 21, since the dose of X-rays irradiated to the calibration phantom 80 increases, data necessary for a small number of times (number of divisions) can be obtained. Therefore, the time required for acquiring data of the calibration phantom 80 can be further shortened, and the measurement throughput of the inspected object 70 can be improved.

In the above embodiment, the inspected object 70 is a semiconductor device, but other objects may be used as the inspected object.

Although described above with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that there is.

11 ... stage 12 ... X-ray tube, 12T ... object, 14, 15 ... X-ray detector 50 ... control part, 70 ... test object, 80 ... calibration phantom, F1 ... focus

Claims (7)

X-ray tube for irradiating X-rays;
A stage having a loading surface on which the inspected object is loaded;
A calibration phantom disposed on the stage;
An X-ray detector in the vicinity of a position facing the X-ray tube around the stage, and a detection surface incident on the X-ray is disposed obliquely with respect to the axial direction of the X-rays radiated from the X-ray tube; And
Generating a cross-section image of the calibration phantom taken by the X-ray detector, detecting the position of the calibration phantom in the cross-section image and adjusting the X-ray focus position according to the detected position of the calibration phantom And a control unit for performing a first process and a second process for generating a stereoscopic image of the inspected object photographed by the X-ray detector,
In the first process, the control unit rotates the X-ray detector, acquires less shooting data of the calibration phantom than the shooting data of the inspected object, and reconstructs the acquired shooting data to generate a stereoscopic image of the calibration phantom. X-ray inspection apparatus characterized in that the cross-section of one of the images is defined as the cross-sectional image. The X-ray inspection apparatus according to claim 1, wherein the control unit adjusts the X-ray focus position based on a difference between a position and a reference position of the calibration phantom detected in the cross-sectional image. The X-ray inspection according to claim 1, wherein the control unit generates a stereoscopic image of the inspected object by reconstructing a plurality of photographed data obtained by rotating the X-ray detector more than half a turn in the second process. Device. The X-ray inspection apparatus according to claim 1, wherein the control unit performs the second processing after the first processing. The X-ray inspection apparatus according to claim 1, wherein the control unit performs the first processing whenever the second processing is performed once. The X-ray inspection apparatus according to claim 1, wherein the control unit performs the first processing whenever the second processing is performed multiple times. The method of claim 1, further comprising a filter that is disposed detachably between the X-ray tube and the stage, and absorbs a specific wavelength among the X-rays,
The controller removes the filter between the X-ray tube and the stage in the first process, and inserts the filter between the X-ray tube and the stage in the second process.

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