JP2017156328A - X-ray inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray inspection device that can perform highly precise inspection while preventing the deterioration in characteristic of a subject.SOLUTION: An X-ray inspection device includes a stage 2 on which a subject S is placed, an X-ray source 3 that emits X-rays to the subject S, X-ray detectors 4 and 5 that detect the X-rays having transmitted the subject S, and a filter 9 disposed between the stage 2 and the X-ray source 3. The filter 9 absorbs the X-rays with a particular wavelength range. The filter 9 includes a plurality of filter plates 9a and 9b that absorbs the X-rays with the different wavelength ranges. The filter plates 9a and 9b are disposed in a manner that the filter plates 9a and 9b can be freely inserted into or removed from between the stage 2 and X-ray source 3.SELECTED DRAWING: Figure 1

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 sucked and mounted on a mounting board, and a solder substrate or other bump provided on the back surface of the semiconductor chip is heated and melted to mount the mounting board. To thermocompression.

  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 become very narrow. For this reason, in the semiconductor chip mounting process, by using through electrodes (TSV) instead of bumps, the above-described reduction in size and pitch is realized.

  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 (for example, position) of the through electrode from the amount of X-ray absorption that has passed through the semiconductor chip (see, for example, Patent Documents 1 and 2).

  On the other hand, since X-rays have high energy that penetrates an object, they may adversely affect semiconductor devices such as characteristic deterioration. For example, in a semiconductor device such as a semiconductor memory, when X-rays are irradiated, semiconductor silicon may be charged by transmission of X-rays. This adversely affects the on / off characteristics of the transistors formed in the semiconductor memory.

Japanese Patent No. 4836746 Japanese Patent No. 5567627

  One aspect of the present invention has been proposed in view of such conventional circumstances, and is an X-ray inspection apparatus capable of performing high-definition inspection while preventing characteristic deterioration of the inspection object. One of the purposes is to provide.

[1] An X-ray inspection apparatus according to one aspect of the present invention includes a stage on which an inspection object is placed, an X-ray source that irradiates the inspection object with X-rays, and the inspection object. An X-ray detector for detecting transmitted X-rays, and a filter disposed between the stage and the X-ray source, wherein the filter absorbs a specific wavelength region of the X-rays. Features.

[2] In the X-ray inspection apparatus according to [1], the filter includes a plurality of filter plates that absorb different wavelength ranges of the X-rays, and each of the plurality of filter plates includes the stage. It is good also as a structure arrange | positioned so that attachment or detachment is possible between the X-ray source.

[3] The X-ray inspection apparatus according to [1] or [2], further including a shielding plate disposed between the stage and the X-ray source, wherein the shielding plate includes at least one of the X-rays. It is good also as a structure which shields one part or all.

[4] In the X-ray inspection apparatus according to [3], the shielding plate may have a window portion and may be removably disposed between the stage and the X-ray source. .

[5] The X-ray inspection apparatus according to any one of [1] to [4] may include a stage moving mechanism that moves the stage in a plane.

[6] In the X-ray inspection apparatus according to any one of [1] to [5], the X-ray source may be configured to irradiate the X-ray in a diffused state.

[7] In the X-ray inspection apparatus according to any one of [1] to [6], the X-ray detector is disposed at a position facing the X-ray source across the stage. The detection surface may be arranged perpendicular to the axial direction of the X-rays emitted from the X-ray source.

[8] In the X-ray inspection apparatus according to any one of [1] to [6], the X-ray detector is disposed around a position facing the X-ray source across the stage. In addition, the detection surface may be arranged obliquely with respect to the axial direction of the X-rays emitted from the X-ray source.

[9] The X-ray inspection apparatus according to [8] may include a detector rotation mechanism that rotates the X-ray detector in the circumferential direction.

  As described above, according to the present invention, it is possible to perform a high-definition inspection while preventing the characteristic deterioration of the inspection object.

It is a front view which shows the structure of the X-ray inspection apparatus which concerns on one Embodiment of this invention. It is the top view to which the principal part of the X-ray inspection apparatus shown in FIG. 1 was expanded. It is sectional drawing to which the principal part of the X-ray inspection apparatus shown in FIG. 1 was expanded. It is a graph which shows the spectrum curve of the X-ray by the presence or absence of a filter. It is a schematic diagram for demonstrating the X-ray irradiation angle when obtaining a vertical image and obtaining a stereoscopic image.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that, in the drawings used in the following description, in order to make each component easy to see, the component may be schematically illustrated, and depending on the component, the dimensional scale may be different.

(X-ray inspection equipment)
First, as an embodiment of the present invention, for example, the configuration of the X-ray inspection apparatus 1 shown in FIGS. 1 to 3 will be described. FIG. 1 is a front view showing the configuration of the X-ray inspection apparatus 1. FIG. 2 is an enlarged plan view of a main part of the X-ray inspection apparatus 1. FIG. 3 is an enlarged cross-sectional view of a main part 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-rear direction of the X-ray inspection apparatus 1, and the Z-axis direction is the X-ray inspection apparatus. 1 is shown as the vertical direction (axial direction). 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 an inspection object S is placed, an X-ray source 3 that irradiates the inspection object S with X-rays (shown by broken lines), and A first X-ray detector 4 and a second X-ray detector 5 that detect X-rays transmitted through the inspection object S are provided.

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

  In addition, the stage 2 is used that has transparency to X-rays. In addition to the horizontal direction (X-axis direction and Y-axis direction) described above, the stage 2 can be moved in the vertical direction (Z-axis direction) and can be rotated around the Z-axis (circumferential direction). It is good.

  The X-ray source 3 is disposed above the placement surface 2a (stage 2), and irradiates the inspection object S on the placement surface 2a while diffusing 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 detector 4 is disposed at a position facing the X-ray source 3 across the stage 2. Specifically, the first X-ray detector 4 is disposed on the surface of the rotary stage 6 located immediately below the stage 2. The first X-ray detector 4 is arranged so that its detection surface 4a is perpendicular to the axial direction (Z-axis direction) of X-rays emitted from the X-ray source 2.

  The second X-ray inspection device 5 is arranged around a position facing the X-ray source 3 with the stage 2 interposed therebetween. Specifically, the second X-ray inspection device 5 is attached to one of the support arms 7a and 7b facing each other with the first X-ray inspection device 4 interposed therebetween. The second X-ray detector 5 is arranged so that the detection surface 5a is inclined with respect to the axial direction (Z-axis direction) of the X-rays emitted from the X-ray source 3.

  The pair of support arms 7a and 7b are supported in a state where the base end sides are attached to the rotary stage 6 and are erected obliquely upward. The rotary stage 6 is a θ stage supported so as to be rotatable around the Z axis (circumferential direction). In the X-ray inspection apparatus 1, the first X-ray detector 4 and the second X-ray detector 5 are moved in the circumferential direction by a detector rotation mechanism (not shown) such as a motor provided on the rotary stage 6. Can be rotated.

  Note that 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. Further, the same X-ray detector 4 and second X-ray detector 5 can be used.

  By the way, in the X-ray inspection apparatus 1 of this embodiment, it is possible to selectively arrange the shielding plate 8 and the filter 9 between the stage 2 and the X-ray source 3. Specifically, specific configurations of the shielding plate 8 and the filter 9 will be described with reference to FIGS. FIG. 2 is an enlarged plan view of the main part of the X-ray inspection apparatus 1. FIG. 3 is an enlarged cross-sectional view of a main part of the X-ray inspection apparatus 1.

  As shown in FIGS. 2 and 3, the shielding plate 8 serves as a collimator that shields at least a part or all of the X-rays and narrows the range through which the X-rays pass. Specifically, the shielding plate 8 is made of a metal plate such as lead, and is slidably attached to a frame not shown. A rectangular window portion 8 a is provided at a position of the shielding plate 8 facing the X-ray source 3.

  The shielding plate 8 is driven to slide by actuators 10a and 10b provided on the frame. Thereby, the shielding board 8 is arrange | positioned so that insertion / removal is possible between the position which lets an X-ray pass from the window part 8a, and the position which interrupts | blocks an X-ray in parts other than the window part 8a. Further, by moving the window portion 8a, the X-ray irradiation position (region) for the inspection object S can be changed.

  The filter 9 has a plurality of (two in this embodiment) filter plates 9a and 9b. The filter plates 9a and 9b absorb (cut) different wavelength regions of the X-rays. Specifically, each filter plate 9a, 9b is slidably attached to the shielding plate 8 so as to overlap with the window portion 8a of the shielding plate 8.

  The filter plates 9a and 9b are slide-driven by actuators 11a and 11b provided on the shielding plate 8. Thereby, each filter board 9a, 9b is arrange | positioned so that insertion / removal is possible between the position which overlaps with the window part 8a, and the position which does not overlap with the window part 8a. The filter plates 9a and 9b are different in material, thickness, and the like, and change the wavelength range of the X-rays irradiated to the inspection object S by selectively moving the filter plates 9a and 9b to a position overlapping the window portion 8a. Is possible.

  Here, when the filter plates 9a and 9b are in positions that do not overlap with the window portion 8 (when there is no filter 9), and when the filter plates 9a and 9b overlap with the window portion 8. FIG. 4 shows the X-ray spectrum curve B (when the filter 9 is provided). In FIG. 4, the spectrum curve A and the spectrum curve B are relatively shown by converting their maximum values to 1.

  Like the spectrum curve A shown in FIG. 4, the X-ray includes a continuous wavelength region. Of these, the longer wavelength region of X-rays greatly affects the characteristic deterioration of a semiconductor device (inspection object S) such as a semiconductor memory. Therefore, as shown by the spectrum curve B shown in FIG. 4, a longer wavelength range (specific wavelength range) that affects the semiconductor device is cut by a combination of the plurality of filter plates 9a and 9b. Thereby, high-definition X-ray inspection can be performed while suppressing deterioration of characteristics of the semiconductor device (inspection object S).

(X-ray inspection)
Next, an X-ray inspection using the X-ray inspection apparatus 1 will be described by taking, as an example, a case where a semiconductor device is inspected as the inspection object S, for example. The inspection object S is not limited to a semiconductor device, and any object that can be inspected by X-rays may be used.

  In the X-ray inspection apparatus 1 of the present embodiment, a vertical (2D) image of the inspection object S can be obtained by direct-view imaging using the first X-ray detector 4. Specifically, in this direct-view imaging, the material and thickness of the filter plates 9a and 9b, the opening diameter of the window portion 8a, and the like are set according to the type of the inspection object S. Thereafter, the first X-ray detector 4 performs imaging while moving the inspection object S in the plane and vertically irradiating the inspection target position with X-rays. Then, the inspection object S can be inspected from the obtained vertical (2D) image.

  On the other hand, 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 second X-ray detector 5. Specifically, in this perspective photographing, the material and thickness of the filter plates 9a and 9b, the opening diameter of the window portion 8a, and the like are set according to the type of the inspection object S. Thereafter, the first imaging by the second X-ray detector 5 is performed while the inspection object S is moved in the plane and X-rays are obliquely irradiated to the inspection target position. In addition, after the first imaging is finished, the second detector 5 is shifted in the circumferential direction, the second imaging is performed, and such imaging is repeated over the entire circumference of the inspection object S. Thereafter, a three-dimensional (3D) image of the inspection object S is created based on the obtained plurality of images. Then, the inspection of the inspection object S (CT inspection) can be performed from this stereoscopic (3D) image.

  As described above, in the X-ray inspection apparatus 1 according to the present embodiment, since both a vertical image and a stereoscopic image can be obtained with one apparatus, it is possible to improve work efficiency and work time. It is.

  Moreover, in the X-ray inspection apparatus 1 of this embodiment, since the wavelength range of the X-ray L irradiated to the to-be-inspected object S can be changed, switching the filter plates 9a and 9b according to the to-be-inspected object S, It is possible to perform a high-definition X-ray inspection while suppressing the characteristic deterioration of the object S.

  Here, the X-ray irradiation angle in the case of obtaining a vertical image and the case of obtaining a stereoscopic image will be described with reference to FIG. FIG. 5 schematically shows X-rays emitted from the X-ray source 2 and passing through the filter 9 (filter plates 9a and 9b).

  As shown in FIG. 5, the X-ray irradiation angle with respect to the filter 9 is different between obtaining a vertical image and obtaining a stereoscopic image. That is, when a vertical image is obtained and when a stereoscopic image is obtained, the X-ray passing distance through the filter 9 differs depending on the X-ray irradiation angle. Specifically, the distance (thickness of the filter 9) passing through the X-ray filter 9 irradiated to the first X-ray detector 4 is set to “L”, and X irradiated to the first X-ray detector 4 When the irradiation angle of the X-ray irradiated to the second X-ray detector 5 with respect to the line is “θ”, the distance passing through the X-ray filter 9 irradiated to the second X-ray detector 5 Is represented by “L ÷ cos θ”.

  In the X-ray inspection apparatus 1 of the present embodiment, among the plurality of filter plates 9a and 9b constituting the filter 9, filter plates 9a and 9b having different materials and thicknesses are arranged to drive the actuators 11a and 11b described above. Thus, the position that overlaps the window portion 8a of each filter plate 9a, 9b and the position that does not overlap are switched. Thereby, it is possible to change the wavelength range of the X-ray L irradiated to the to-be-inspected object S, switching the filter plates 9a and 9b according to the to-be-inspected object S.

  Further, in the X-ray inspection of the semiconductor device, since a fine inspection target position is inspected, the X-ray irradiation range at the inspection target position is very narrow as 1 mm or less. For this reason, the X-ray irradiation is indirectly received except for the inspection target position.

  On the other hand, in the X-ray inspection apparatus 1 according to the present embodiment, X-rays are irradiated at positions other than the inspection target position by shielding the portions other than the inspection target position with the shielding plate 9 while changing the position of the window portion 9a. It is possible to prevent this.

  Furthermore, in the X-ray inspection apparatus 1 of the present embodiment, the X-ray irradiation range can be shielded by the shielding plate 9 after the end of imaging. Thereby, it is possible to prevent X-rays from being unnecessarily irradiated (exposed) to the inspection object S.

  DESCRIPTION OF SYMBOLS 1 ... X-ray inspection apparatus 2 ... Stage 3 ... X-ray source 4 ... 1st X-ray detector 5 ... 2nd X-ray detector 6 ... Rotary stage 7a, 7b ... Support arm 8 ... Shielding plate 8a ... Window part DESCRIPTION OF SYMBOLS 9 ... Filter 9a, 9b ... Filter board 10a, 10b ... Actuator 11a, 11b ... Actuator S ... Test object

Claims (9)

A stage on which the object to be inspected is placed;
An X-ray source for irradiating the inspection object with X-rays;
An X-ray detector for detecting X-rays transmitted through the inspection object;
A filter disposed between the stage and the X-ray source;
The X-ray inspection apparatus, wherein the filter absorbs a specific wavelength region of the X-ray. The filter has a plurality of filter plates that absorb different wavelength regions of the X-ray,
The X-ray inspection apparatus according to claim 1, wherein each of the plurality of filter plates is detachably disposed between the stage and the X-ray source. A shielding plate disposed between the stage and the X-ray source;
The X-ray inspection apparatus according to claim 1, wherein the shielding plate shields at least a part or all of the X-rays.   The X-ray inspection apparatus according to claim 3, wherein the shielding plate has a window portion and is detachably disposed between the stage and the X-ray source.   The X-ray inspection apparatus according to claim 1, further comprising a stage moving mechanism that moves the stage in a plane.   The X-ray inspection apparatus according to claim 1, wherein the X-ray source irradiates the X-ray in a diffused state.   The X-ray detector is disposed at a position facing the X-ray source across the stage, and its detection surface is disposed perpendicular to the axial direction of the X-rays emitted from the X-ray source. The X-ray inspection apparatus according to any one of claims 1 to 6, wherein   The X-ray detector is disposed around a position facing the X-ray source across the stage, and its detection surface is inclined with respect to the axial direction of the X-ray irradiated from the X-ray source. The X-ray inspection apparatus according to claim 1, wherein the X-ray inspection apparatus is arranged.   The X-ray inspection apparatus according to claim 8, further comprising a detector rotation mechanism that rotates the X-ray detector in a circumferential direction.

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