JP2009109276A - Inspection apparatus and inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection apparatus capable of finding cracks, even when employing a low-magnification lens. <P>SOLUTION: The inspecting apparatus which has an infrared irradiating means 3 for irradiating a translucent work piece 1 with infrared radiation, and an imaging means 4 for receiving infrared radiation passing through the translucent work piece 1 and photographing an infrared image of the translucent work piece 1, based on the received infrared radiation, is configured such that the photographing direction A of the imaging means 4 with respect to the translucent work piece 1 is made variable. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inspection apparatus and an inspection method for inspecting the presence or absence of cracks by irradiating a translucent workpiece with infrared rays to capture an infrared image thereof.

  As an inspection apparatus for inspecting the presence or absence of minute cracks (hereinafter referred to as cracks) generated in a semiconductor wafer, for example, there is an inspection apparatus disclosed in Patent Document 1. As shown in FIG. 10, the inspection apparatus of Patent Document 1 receives a movable base 200 that supports a semiconductor wafer 100, an infrared irradiation means 300 that irradiates the semiconductor wafer 100 with infrared rays, and infrared rays that have passed through the semiconductor wafer 100. A camera 400 that captures an image, a monitor 500 that displays an image captured by the camera 400, and the like.

  When using this inspection apparatus to inspect the presence or absence of cracks in a semiconductor wafer, first, the semiconductor wafer 100 is placed on the movable table 200, and the movable table 200 is moved to attach the semiconductor wafer 100 to the infrared irradiation means 300 and It is arranged at an appropriate position with respect to the camera 400. Next, the infrared irradiation unit 300 irradiates the semiconductor wafer 100 with infrared rays. Infrared light that has passed through the semiconductor wafer 100 is received by the lens 400a of the camera 400 and connected to a light receiving element inside the camera 400 to form an infrared image of the semiconductor wafer 100. This infrared image is converted into an electrical signal by the camera 400 and sent to the monitor 500, where it is displayed as a contrast image.

  At this time, if there is a crack in the image capturing range of the semiconductor wafer 100, the cracked portion appears as a shadow in the contrast image of the monitor 500. In general, the presence / absence of a crack is determined by the inspector viewing an image displayed on the monitor 500.

In FIG. 10, a member denoted by reference numeral 600 is an infrared leakage prevention member for preventing the leaked infrared rays from directly entering the camera 400 when observing the end portion of the semiconductor wafer 100. Thereby, a sufficient contrast ratio of the infrared image can be obtained.
JP 2006-351669 A

  The width of the crack formed in the semiconductor wafer is as small as 1 μm. Therefore, a high-magnification objective lens is usually used as the lens used in the inspection apparatus. However, the observation with a high-magnification lens has a drawback that the efficiency of the inspection work is deteriorated because the field of view is narrowed.

  In order to widen the observation field of view, a low-power lens is simply used. However, as shown in FIG. 11, when the crack C is formed so as to be substantially parallel to the imaging direction of the camera indicated by the dotted line, the imaging width Z of the crack C that can be imaged by the camera is the crack C. Therefore, the shadow of the crack displayed on the monitor becomes very thin. Therefore, in such a case, if a low-magnification lens is used, it is difficult to find a crack, and the crack may be missed.

  Therefore, in view of the above problems, the present invention provides an inspection apparatus and an inspection method capable of finding a crack even when a low-power lens is used.

  According to a first aspect of the present invention, an infrared irradiation means for irradiating an infrared ray to a translucent work, and receiving an infrared ray transmitted through the translucent work and taking an infrared image of the translucent work based on the received infrared ray. In the inspection apparatus including the imaging unit, the imaging direction of the imaging unit with respect to the translucent workpiece can be changed.

  When inspecting the presence or absence of cracks in a translucent workpiece, the inspection target portion of the translucent workpiece is imaged from a predetermined imaging direction. Thereafter, the imaging direction is changed and the inspection target part is imaged again. If the crack formed in the translucent workpiece is arranged substantially parallel to the imaging direction when the imaging is performed in the first imaging direction, the imaging width of the crack is the width of the crack (about 1 μm). Since the width is almost the same, the image is captured very finely. However, in the second imaging after changing the imaging direction, the crack can be imaged from an oblique direction, so that the imaging width can be increased. Thus, by imaging the inspection target part of the translucent workpiece from at least two directions, it becomes easy to find a crack generated in the translucent workpiece, and the oversight of the crack can be prevented.

  According to a second aspect of the present invention, in the inspection apparatus according to the first aspect, the imaging unit includes a camera including a lens that receives infrared rays that have passed through the translucent work, and It is configured such that the imaging direction with respect to the translucent work can be changed by relatively changing the direction of the lens.

  By changing the direction of the lens relative to the translucent workpiece, the inspection target portion of the translucent workpiece can be imaged from at least two directions. Thereby, it becomes easy to find the crack which arose in the translucent workpiece | work, and it can prevent overlooking of a crack.

  According to a third aspect of the present invention, in the inspection apparatus according to the first aspect, the imaging means includes a camera including a lens that receives infrared light transmitted through the translucent work, the translucent work, and the camera. A mirror that is interposed between and reflects the infrared rays that have passed through the translucent workpiece to guide the lens, and rotates the mirror around an axis that passes through the translucent workpiece and the lens, The imaging direction with respect to the translucent workpiece can be changed.

  The imaging direction can be changed simply by rotating the mirror around the axis. That is, when changing the imaging direction, the camera and the translucent work are not moved, so that it is not necessary to focus the camera on the translucent work. Thereby, operability is improved.

  According to a fourth aspect of the present invention, in the inspection apparatus according to any one of the first to third aspects, the translucent workpiece is a semiconductor wafer.

  The inspection apparatus of the present invention can be applied as a semiconductor wafer crack inspection apparatus.

  According to a fifth aspect of the present invention, in the inspection method for irradiating the translucent workpiece with infrared rays and capturing an infrared image of the translucent workpiece based on the infrared rays transmitted through the translucent workpiece, This is a method of imaging the inspection target part from at least two directions.

  By this method, it becomes easy to find the crack which arose in the translucent workpiece | work, and it can prevent overlooking of a crack.

  According to the inspection apparatus and the inspection method of the present invention, when a light-transmitting workpiece is imaged, even if the cracks are disposed substantially parallel to the imaging direction, the imaging of the light-transmitting workpiece is performed thereafter. The crack can be imaged from an oblique direction by changing the direction and imaging again. As a result, a crack that has a narrow imaging width in the first imaging and is difficult to find is easily captured in the second imaging because the imaging width is thick. And it is possible to prevent the crack from being overlooked, and to provide a high-quality product. In addition, cracks that have been difficult to find with low-power lenses can be found. By reducing the magnification of the lens used, the observation field of view can be expanded, and the inspection work efficiency can be improved.

FIG. 1 is an overall configuration diagram showing a first embodiment of an inspection apparatus of the present invention. Hereinafter, the configuration of the inspection apparatus of the present invention will be described with reference to FIG.
The inspection apparatus of the present invention includes a movable table 2, infrared irradiation means 3, imaging means 4, and a monitor 5.

  The movable table 2 supports the semiconductor wafer 1 as a translucent work, and is configured to be movable in the horizontal direction and the vertical direction by a moving mechanism (not shown).

  The infrared irradiation means 3 is an infrared light source capable of emitting infrared rays. As the infrared irradiation means 3, for example, a device arbitrarily selected from known infrared irradiation devices such as a halogen lamp can be applied.

  The imaging means 4 includes a camera 6 and a reflection guiding unit 8 interposed between the semiconductor wafer 1 and the camera 6. The camera 6 has a lens 6 a for receiving infrared rays that have passed through the semiconductor wafer 1. In the camera 6, a light receiving element (not shown) that forms an infrared image of the semiconductor wafer 1 by connecting infrared rays received by the lens 6 a is provided.

  An infrared image of the semiconductor wafer 1 formed in the camera 6 is converted into an electric signal and transmitted to the monitor 5. The monitor 5 displays an image based on the electrical signal received from the camera 6.

  The reflection guiding unit 8 has two mirrors 7a and 7b. The two mirrors 7 a and 7 b are integrally attached to the main body of the reflection guiding unit 8, respectively. These mirrors 7a and 7b are disposed on both sides of an axis X (in the vertical direction in FIG. 1) passing through the semiconductor wafer 1 and the lens 6a, and their reflecting surfaces are opposed to each other with a predetermined angle. It is installed. The angles of the mirrors 7a and 7b are set so as to sequentially reflect the infrared light transmitted through the semiconductor wafer 1 and guide it to the lens 6a of the camera 6.

  The dotted line in FIG. 1 shows the infrared path guided by the two mirrors 7a and 7b. Of the two mirrors 7a and 7b, the first mirror 7a that reflects infrared rays is called the first mirror, and the second mirror 7b that reflects infrared rays is called the second mirror. The direction is an imaging direction for capturing an image of the semiconductor wafer 1.

  The reflection guiding unit 8 is configured to be rotatable about the axis X. As the reflection guiding unit 8 rotates about the axis X, the two mirrors 7a and 7b rotate integrally around the axis X.

  FIG. 2 shows a state in which the reflection guiding unit 8 of FIG. 1 is rotated 180 degrees around the axis X. As the reflection guiding unit 8 is rotated by 180 degrees, the two mirrors 7a and 7b are moved from the state shown in FIG. In the state shown in FIG. 2, the direction of the path A of infrared rays incident on the first mirror 7a, that is, the imaging direction is set to be symmetrical with respect to the imaging direction A in the state of FIG. Yes. Thus, the inspection apparatus of the present invention is configured to be able to change the imaging direction.

FIG. 3 shows a second embodiment of the inspection apparatus of the present invention.
The inspection apparatus according to this embodiment includes a movable table 9, infrared irradiation means 10, imaging means 11, and a monitor 12. The imaging means 11 is a camera 13 having a lens 13a.

  The movable table 9 supports the semiconductor wafer 1 in a horizontal manner and has a moving mechanism in the horizontal direction and the vertical direction. Further, as shown in FIG. 4, the movable table 9 has a tilt mechanism that tilts the semiconductor wafer 1 by an angle θ with respect to the horizontal plane.

  In this embodiment, the imaging direction A indicated by the dotted line in FIGS. 3 and 4 is fixed in the vertical direction. However, by inclining the semiconductor wafer 1 with respect to the horizontal plane, the imaging direction A with respect to the semiconductor wafer 1 can be changed from the orthogonal direction shown in FIG. 3 to the oblique direction shown in FIG.

  As shown in FIG. 4, the main body 13b of the camera 13 having a light receiving element or the like inside is configured to be tiltable with respect to the lens 13a. Specifically, it is possible to incline the main body 13b by an angle α with respect to the vertical axis from the state in which the main body 13b and the lens 13a are arranged coaxially in the vertical direction (see FIG. 4). .

  The infrared irradiation unit 10 and the monitor 12 have the same configuration as the infrared irradiation unit 3 and the monitor 5 of the first embodiment described with reference to FIGS.

Hereinafter, the usage method (inspection method) of the inspection apparatus of the present invention will be described.
First, a method of using the inspection apparatus according to the first embodiment described with reference to FIGS. 1 and 2 will be described. As shown in FIG. 1, a semiconductor wafer 1 as an inspection object is placed on a movable table 2, and the movable table 2 is moved so that the semiconductor wafer 1 is moved with respect to the infrared irradiation unit 3 and the imaging unit 4. Place it in an appropriate position.

  Infrared rays are irradiated from the infrared irradiation means 3 to the semiconductor wafer 1. The infrared light transmitted through the semiconductor wafer 1 is sequentially reflected by the first mirror 7 a and the second mirror 7 b and guided to the lens 6 a of the camera 6. Then, the infrared light received by the lens 6 a is connected to a light receiving element inside the camera 6 to form an infrared image of the semiconductor wafer 1. This infrared image is converted into an electrical signal by the camera 6 and sent to the monitor 5, and displayed on the monitor 5 as a contrast image.

  If there is a crack in the imaged semiconductor wafer 1, the cracked portion appears as a shadow in the contrast image displayed on the monitor 5. The inspector can confirm the presence of a crack by checking the shadowed portion by visual inspection or the like.

  Thereafter, the reflection guiding unit 8 is rotated by 180 degrees around the axis X, and the imaging direction A shown in FIG. 1 is changed to the imaging direction A shown in FIG. Then, the inspection target portion of the semiconductor wafer 1 is imaged again in the imaging direction A shown in FIG. Thus, the inspection method of the present invention images the inspection target portion of the semiconductor wafer 1 from two directions.

The effect | action which images the test object part of a semiconductor wafer from two directions is demonstrated with reference to FIG. 5 and FIG.
FIG. 5 is an enlarged view of a main part of FIG. As shown in FIG. 5, when the crack C formed in the semiconductor wafer 1 is arranged substantially parallel to the imaging direction A, the imaging width Z1 of the crack C that can be captured by the camera is the width W of the crack C. And almost the same width. Since the width W of the crack C is about 1 μm and is very small, the shadow of the crack C projected on the monitor 5 in this case is very thin. In particular, when a low-magnification lens 6 a is used, it is difficult to find the crack C from the image displayed on the monitor 5.

  Therefore, the reflection guiding unit 8 is rotated 180 degrees about the axis X to switch from the state shown in FIG. 1 to the state shown in FIG. 2, and the imaging direction A with respect to the semiconductor wafer 1 is changed.

  FIG. 6 is an enlarged view of the main part of FIG. As shown in FIG. 6, the crack C extends in the thickness T direction of the semiconductor wafer 1. Since the depth dimension D of the crack C is related to the thickness T of the semiconductor wafer 1, it is about 200 μm to 300 μm. Therefore, the depth dimension D of the crack C is very large compared to the width W (about 1 μm). By changing the imaging direction A as described above, the crack C can be switched from the observation facing the width W shown in FIG. 5 to the observation facing the depth dimension D shown in FIG. Thereby, the imaging width Z2 in FIG. 6 can be made larger than the imaging width Z1 in FIG.

  As described above, in the inspection method of the present invention, a crack whose imaging width is small and difficult to find in the first imaging is observed with a larger imaging width in the second imaging after changing the imaging direction. Can do. Therefore, even when a low-power lens is used, it is easy to find a crack and prevent oversight. In addition, since the low-power lens can secure a wider field of view than the high-power lens, the inspection work efficiency is also improved.

Next, a method of using the inspection apparatus according to the second embodiment described with reference to FIGS. 3 and 4 will be described.
First, as shown in FIG. 3, infrared light is irradiated from the infrared irradiation means 10 to the semiconductor wafer 1 while the semiconductor wafer 1 is horizontally supported by the movable base 9. An infrared image transmitted through the semiconductor wafer 1 is picked up by the camera 13 and displayed on the monitor 12 to inspect for cracks. Since the operation from the infrared irradiation process by the infrared irradiation means 10 to the display process on the monitor 12 is the same as the operation of the first embodiment, the description thereof is omitted.

  FIG. 7 is an enlarged view of the main part of FIG. As shown in FIG. 7, when the crack C formed in the semiconductor wafer 1 is arranged substantially parallel to the imaging direction A, the imaging width Z3 of the crack C that can be imaged by the camera is The width is almost the same as the width W. In this case, as in the case of the first embodiment described above, it is difficult to find a crack, particularly with a low-power lens.

  In the second embodiment, the imaging direction A with respect to the semiconductor wafer 1 is orthogonal (shown in FIG. 3) by tilting the semiconductor wafer 1 from the horizontal state shown in FIG. The direction can be changed to an oblique direction (shown in FIG. 4). Thus, the imaging direction A is changed, and the inspection target portion of the semiconductor wafer 1 is imaged from two directions.

  At this time, the main body 13b of the camera 13 is inclined by an angle α with respect to the vertical axis. The reason why the main body 13b of the camera 13 is tilted by the angle α is to adjust the focus of the camera 13 that is shifted with the tilt of the angle θ of the semiconductor wafer 1.

  FIG. 8 is an enlarged view of the main part of FIG. As shown in FIG. 8, since the crack C extends in the thickness T direction of the semiconductor wafer 1, the depth dimension D of the crack C is very large compared to the width W. By tilting the semiconductor wafer 1 by the angle θ and changing the imaging direction A, the crack C can be switched from the observation facing the width W shown in FIG. 7 to the observation facing the depth dimension D shown in FIG. . Thereby, the imaging width Z4 in FIG. 8 can be made larger than the imaging width Z3 in FIG.

  In the second embodiment, the imaging direction is changed by moving the semiconductor wafer with respect to the camera lens. On the other hand, the imaging direction may be changed by moving the camera lens with respect to the semiconductor wafer. For example, as shown in FIG. 9, the camera 14 (and its lens 14a) is pivoted around the vertical axis shown in FIG. Thus, the imaging direction A with respect to the semiconductor wafer 1 can be changed.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention. In the above-described embodiment, the case where the inspection target portion of the semiconductor wafer is imaged from two directions has been described as an example, but the image may be captured from three or more imaging directions. Moreover, you may image using two or three or more cameras from which an imaging direction mutually differs (illustration omitted). As long as the inspection object to be inspected by the inspection apparatus of the present invention is a member that can transmit infrared rays, it is possible to apply an electronic component other than a semiconductor wafer or a light-transmitting workpiece other than that.

It is a whole lineblock diagram showing a 1st embodiment of an inspection device of the present invention. It is a whole block diagram which shows the state which changed the imaging direction of the said test | inspection apparatus. It is a whole block diagram which shows 2nd Embodiment of the test | inspection apparatus of this invention. It is a whole block diagram which shows the state which changed the imaging direction of the said test | inspection apparatus. It is the figure which expanded the principal part of FIG. It is the figure which expanded the principal part of FIG. It is the figure which expanded the principal part of FIG. It is the figure which expanded the principal part of FIG. It is a simplified diagram showing still another embodiment of the present invention. It is a whole block diagram which shows the conventional inspection apparatus. It is the figure which expanded the principal part of FIG.

Explanation of symbols

1 Semiconductor wafer (translucent workpiece)
DESCRIPTION OF SYMBOLS 3 Infrared irradiation means 4 Imaging means 6 Camera 6a Lens 7a Mirror 7b Mirror 10 Infrared irradiation means 11 Imaging means 13 Camera 13a Lens A Imaging direction C Crack X Axis

Claims (5)

Infrared irradiation means for irradiating the translucent work with infrared light, and imaging means for receiving the infrared light transmitted through the translucent work and taking an infrared image of the translucent work based on the received infrared light In inspection equipment,
An inspection apparatus configured to be able to change an imaging direction of the imaging means with respect to the translucent workpiece.   The imaging means includes a camera including a lens that receives infrared rays transmitted through the translucent work, and changes a direction of the lens relative to the translucent work to The inspection apparatus according to claim 1, wherein the imaging direction can be changed.   The imaging means includes a camera including a lens that receives infrared light transmitted through the translucent work, and reflects the infrared light that is interposed between the translucent work and the camera and is transmitted through the translucent work. And a mirror for guiding the lens to the lens, and the mirror is rotated about an axis passing through the translucent work and the lens to change an imaging direction with respect to the translucent work. The inspection device described.   The inspection apparatus according to claim 1, wherein the translucent workpiece is a semiconductor wafer. In the inspection method for irradiating the translucent workpiece with infrared rays and capturing an infrared image of the translucent workpiece based on the infrared rays transmitted through the translucent workpiece,
An inspection method characterized in that an inspection target part of the translucent workpiece is imaged from at least two directions.

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