JP6719272B2 - X-ray inspection device - Google Patents

Description

The present invention relates to an X-ray inspection apparatus.

For example, in a semiconductor chip mounting process, a semiconductor chip cut out from a semiconductor wafer is adsorbed and mounted on a mounting substrate, and a bump such as a solder material provided on the back surface of the semiconductor chip is heated and melted to mount the mounting substrate. Thermocompression bond to.

In recent years, with the progress of miniaturization of semiconductor devices, the size of bumps has become very small, and the pitch between bumps has also become very narrow. Therefore, in the process of mounting the semiconductor chip, the through electrodes (TSV) are used instead of the bumps to realize the above-described size reduction and pitch reduction.

By the way, since the through electrode is formed in a state of being embedded in the semiconductor chip, the state cannot be confirmed from the appearance of the semiconductor chip. Therefore, an X-ray inspection apparatus is used to inspect the state of the penetrating electrode (for example, defect position) from the absorption amount of X-rays transmitted through the semiconductor chip (see, for example, Patent Document 1).

Specifically, in Patent Document 1, a plurality of X-ray detectors are arranged side by side in the circumferential direction in a plane facing the X-ray source with the stage interposed therebetween, and the plurality of X-ray detectors can be moved in the radial direction. The X-ray inspection apparatus is disclosed.

However, in such an X-ray inspection apparatus, since the X-ray detector is moved in the radial direction to change only the magnification with respect to the inspection object, an image of the inspection object obtained by one-time imaging is displayed. He had restrictions. Further, in order to specify the defect position of the semiconductor chip described above, it is necessary to repeatedly perform imaging using a plurality of X-ray detectors, and it is difficult to specify the optimum inspection position of the inspection object with a small number of images. Met.

In addition, since X-rays have high energy that penetrates an object, they may adversely affect the semiconductor device such as characteristic deterioration. For example, in a semiconductor device such as a semiconductor memory, if X-rays are irradiated for a long time, the semiconductor silicon may be charged due to the transmission of X-rays. This adversely affects the on/off characteristics of the transistor formed inside the semiconductor memory.

Japanese Patent No. 5125297

One aspect of the present invention has been proposed in view of such conventional circumstances, and it is possible to obtain a wide-field image and a high-definition image of an object to be inspected at the same time with a single imaging, An object of the present invention is to provide an X-ray inspection apparatus capable of specifying an optimum inspection position of an inspection object with a small number of images.

[1] An X-ray inspection apparatus according to one aspect of the present invention includes a stage on which an object to be inspected is placed, an X-ray source for irradiating the object to be inspected with X-rays, and the object to be inspected. A plurality of X-ray detectors for detecting the transmitted X-rays, wherein the plurality of X-ray detectors are arranged side by side around a position facing the X-ray source with the stage interposed therebetween, and respectively. Of the plurality of X-ray detectors are arranged obliquely with respect to the axial direction of the X-rays emitted from the X-ray source, and at least one X-ray detector and another X-ray detector are provided. An image of the inspection position of the inspection object is simultaneously captured in different fields of view, and the one X-ray detector includes a detection surface of relatively low pixels and is relatively low with respect to the inspection position. An image with a relatively wide field of view is captured at a magnification position, and the other X-ray detector includes a detection surface with a relatively high pixel, and a position with a relatively high magnification with respect to the inspection position. In, a relatively narrow-field image is captured .

[ 2 ] The X-ray inspection apparatus according to [1 ] , further comprising a detector rotation mechanism that rotates the plurality of X-ray detectors in the circumferential direction.

[ 3 ] In the X-ray inspection apparatus according to [1] or [ 2], the X-ray source irradiates the X-ray in a diffused state.

[ 4 ] The X-ray inspection apparatus according to any one of [1] to [ 3 ], further including a stage moving mechanism that moves the stage in a plane.

[ 5 ] In the X-ray inspection apparatus according to any one of [1] to [ 4 ], the X-ray inspection apparatus is arranged at a position facing the X-ray source with the stage interposed therebetween, and a detection surface thereof is the X-ray. An X-ray detector arranged perpendicularly to the axial direction of the X-ray emitted from the radiation source is provided.

As described above, according to the X-ray inspection apparatus according to one aspect of the present invention, it is possible to simultaneously obtain a wide-field image and a high-definition image of the object to be inspected with one image capturing, and with a small amount of image capturing. It is possible to specify the optimum inspection position of the inspection object.

1 shows a configuration example of an X-ray inspection apparatus according to an embodiment of the present invention, (a) is a perspective view thereof, and (b) is a plan view thereof. FIG. 2 shows an X-ray inspection using the X-ray inspection apparatus shown in FIG. 1, where (a) is a schematic diagram showing a wide-field image obtained by the first X-ray detector, and (b) is a second X-ray. It is a schematic diagram which shows the high-definition image obtained by the detector.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In addition, in the drawings used in the following description, the constituent elements may be schematically illustrated in order to make the constituent elements easy to see, and the scale of the dimensions may be different depending on the constituent elements.

(X-ray inspection device)
First, as an embodiment of the present invention, a configuration example of the X-ray inspection apparatus 1 shown in FIGS. 1A and 1B will be described. Note that FIG. 1A is a perspective view showing the configuration of the X-ray inspection apparatus 1. FIG. 1B is a plan view showing the configuration of the X-ray inspection apparatus 1.

In the drawings shown below, an XYZ orthogonal coordinate system is set, the X-axis direction is the left-right direction of the X-ray inspection apparatus 1, the Y-axis direction is the front-back direction of the X-ray inspection apparatus 1, and the Z-axis direction is the X-ray inspection apparatus. The vertical direction (axial direction) of 1 is shown respectively. Further, the rotation around the Z axis is shown as the rotation direction (circumferential direction) of the X-ray inspection apparatus 1.

As shown in FIG. 1, the X-ray inspection apparatus 1 includes a stage 2 on which the inspection object S is mounted, an X-ray source 3 for irradiating the inspection object S with X-rays, and an inspection object S. It is provided with a first X-ray detector 4 and a second X-ray detector 5 that detect the transmitted X-rays.

The stage 2 is an XY stage having a mounting surface 2a on which the inspection object S is mounted and supported movably in the horizontal direction (X-axis direction and Y-axis direction). In the X-ray inspection apparatus 1, a stage moving mechanism (not shown) such as an actuator provided on the stage 2 moves the stage 2 in the plane. This makes it possible to guide the inspection object S placed on the placement surface 2a to a predetermined inspection target position.

As the stage 2, a stage that is transparent to X-rays is used. In addition to the horizontal direction (X-axis direction and Y-axis direction) described above, the stage 2 is movable in the vertical direction (Z-axis direction) and rotatable about the Z-axis (circumferential direction). May be

The X-ray source 3 is disposed above the mounting surface 2a (stage 2), and radiates the inspection object S on the mounting surface 2a while diffusing the X-rays in a conical shape. The X-ray source 3 is not particularly limited, and those conventionally used in X-ray inspection can be used.

The first X-ray inspection device 4 and the second X-ray inspection device 5 are arranged side by side in the circumferential direction at a predetermined angle θ ₁ around the position facing the X-ray source 3 with the stage 2 interposed therebetween. .. In addition, the first X-ray detector 4 and the second X-ray detector 5 have their respective detection surfaces 4a and 5a with respect to the axial direction (Z-axis direction) of the X-rays emitted from the X-ray source 3. It is arranged so as to be inclined at a predetermined angle θ ₂ . Further, in the X-ray inspection apparatus 1, the first X-ray detector 4 and the second X-ray detector 5 can be rotated in the circumferential direction by a detector rotation mechanism (not shown) such as a rotation motor. It is possible.

In the present embodiment, the first X-ray inspector 4 and the second X-ray inspector 5 have an angle θ ₁ of, for example, 60° around the position facing the X-ray source 3 with the stage 2 in between. Are arranged side by side in the circumferential direction. Further, the first X-ray detector 4 and the second X-ray detector 5 are arranged with respect to the axial direction (Z-axis direction) of the X-rays emitted from the X-ray source 3 on the respective detection surfaces 4a, 5a. , Are arranged so as to be inclined at an angle θ ₂ of 60°, for example.

The first X-ray detector 4 includes a detection surface 4 a having a lower pixel count than the second X-ray detector 5. The first X-ray detector 4 is arranged at a position with a lower magnification (farther focal length) than the second X-ray detector 5 with respect to the inspection position of the inspection object S. As a result, the first X-ray detector 4 can capture an image with a wider field of view than the second X-ray detector 5.

The second X-ray detector 5 includes a detection surface 5 a having a higher pixel count than the second X-ray detector 5. The second X-ray detector 5 is arranged at a position with a higher magnification (closer focal length) than the first X-ray detector 4 with respect to the inspection position of the inspection object S. Thereby, the second X-ray detector 5 can capture a higher-definition image than the first X-ray detector 4.

The first X-ray detector 4 and the second X-ray detector 5 are not particularly limited, and those conventionally used in X-ray inspection can be used. Among them, when the photocount type X-ray detector is used, the number of photons can be counted with a small dose, and thus a highly sensitive image can be obtained.

Further, by using Si, CdTe, GaS, or the like as the material of the X-ray detector, it is possible to sort in a wide energy band. Further, since it can be arranged at a distance from the X-ray source 3 by matching with the energy band of the X-ray source 3, it becomes possible to perform high-magnification imaging.

Moreover, although the same thing can be used for the 1st X-ray detector 4 and the 2nd X-ray detector 5, you may use different things. As a result, it becomes possible to detect even the inspection object S having a difference in sensitivity.

(X-ray inspection)
Next, an X-ray inspection using the X-ray inspection apparatus 1 will be described by taking an example of inspecting a semiconductor device as the inspection object S as shown in FIGS. 2A and 2B. .. 2A is a schematic diagram showing a wide-field image P1 of the inspection object S obtained by the first X-ray detector, and FIG. 2B is a schematic diagram by the second X-ray detector. It is a schematic diagram which shows the high-definition image P2 of the to-be-inspected object S obtained.

In the X-ray inspection apparatus 1 of the present embodiment, a stereoscopic (3D) image of the inspection object S can be obtained by perspective imaging using the first X-ray detector 4 and the second X-ray detector 5. .. Specifically, in this perspective imaging, the first S-ray detector 4 and the second X-ray detector 4 are moved while the inspection object S is moved in the plane and the inspection position is obliquely irradiated with X-rays. The first imaging according to 5 is performed. Further, after the first imaging is completed, the positions of the first X-ray detector 4 and the second detector 5 are shifted in the circumferential direction, and the second imaging is performed to cover the entire circumference of the inspection object S. Then, such imaging is repeated. After that, a three-dimensional (3D) image of the inspection object S is created based on the obtained plurality of images. Then, the inspection (CT inspection) of the inspection object S can be performed from this three-dimensional (3D) image.

In the X-ray inspection apparatus 1 of the present embodiment, the wide field image P1 of the inspection object S shown in FIG. 2A by the first X-ray detector 4, and the second X-ray detector 5 shown in FIG. The high-definition image P2 shown in (b) can be obtained at the same time by shooting once. This makes it possible to perform a more precise X-ray inspection after specifying the optimum inspection position (for example, a defect position) of the inspection object S.

Further, in the X-ray inspection apparatus 1 of the present embodiment, the optimum inspection position (for example, the defect position) of the inspection object S can be specified with a small number of images, so that the efficiency of the work and the work time can be shortened. It is possible. Further, since the amount of X-ray exposure can be greatly reduced, it is possible to suppress the characteristic deterioration of the inspection object S due to the influence of X-rays.

It should be noted that the present invention is not necessarily limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
Specifically, the inspection object S to be inspected by the X-ray inspection apparatus 1 is not limited to the above-described semiconductor device, and may be any one that can perform X-ray inspection, and is not particularly limited.

Further, in the X-ray inspection apparatus 1, the circumferential angle θ ₁ of the first X-ray inspection device 4 and the second X-ray inspection device 5 can be arbitrarily changed. Further, it is possible to arbitrarily change the inclination angle θ ₂ of the first X-ray inspection device 4 and the second X-ray inspection device 5 within the range of 0 to 90°.

Of these, the X-ray detector 4 arranged at an angle θ ₂ of 0° is arranged at a position (directly below) facing the X-ray source 3 with the stage 2 interposed therebetween. The detection surface of this X-ray detector is perpendicular to the axial direction of the X-rays emitted from the X-ray source 3 (Z-axis direction).

In this case, a vertical (2D) image of the inspection object S can be obtained by direct-view imaging. Specifically, in this direct-view imaging, it is possible to perform imaging while vertically irradiating the inspection position of the inspection object S with X-rays, and inspect the inspection object S from the obtained vertical (2D) image.

Although the X-ray inspection apparatus 1 has a configuration in which two X-ray detectors 4 and 5 are arranged, the number of X-ray detectors arranged is not limited to the above-mentioned two. However, it is also possible to use three or more. Among them, it is possible to simultaneously capture images at the inspection position of the inspection object S with different fields of view.

DESCRIPTION OF SYMBOLS 1... X-ray inspection apparatus 2... Stage 2a... Mounting surface 3... X-ray source 4... 1st X-ray detector (one X-ray detector) 4a... Detection surface 5... 2nd X-ray detector ( Other X-ray detectors) 5a... Detection surface S... Inspected object P1... Wide-field image P2... High-definition image

Claims (5)

A stage on which the object to be inspected is placed,
An X-ray source for irradiating the inspection object with X-rays;
A plurality of X-ray detectors for detecting X-rays transmitted through the inspection object;
The plurality of X-ray detectors are arranged side by side around a position facing the X-ray source with the stage interposed therebetween, and each detection surface is in the axial direction of X-rays emitted from the X-ray source. Placed diagonally to
Using at least one X-ray detector and another X-ray detector among the plurality of X-ray detectors, images at the inspection position of the inspection object are simultaneously captured in different fields of view ,
The one X-ray detector includes a detection surface of relatively low pixels, and captures an image of a relatively wide field of view at a position of relatively low magnification with respect to the inspection position,
The other X-ray detector includes a detection surface of relatively high pixels, and captures an image of a relatively narrow field of view at a position of relatively high magnification with respect to the inspection position. X-ray inspection device. The X-ray inspection apparatus according to claim 1, further comprising a detector rotation mechanism that rotates the plurality of X-ray detectors in a circumferential direction. The X-ray source, X-rays inspection apparatus according to claim 1 or 2, characterized in that irradiation while spreading the X-ray. X-ray inspection apparatus according to any one of claim 1 to 3, characterized in that it comprises a stage moving mechanism for moving the stage in a plane. One X-ray detector of the plurality of X-ray detectors is arranged at a position facing the X-ray source with the stage interposed therebetween, and its detection surface is irradiated with X-rays from the X-ray source. The X-ray inspection apparatus according to any one of claims 1 to 5 , wherein the X-ray inspection apparatus is arranged perpendicular to the axial direction of the.

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