JP3609136B2 - Semiconductor device inspection method and apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a semiconductor device inspection method and apparatus for inspecting harmful deformations such as leads formed in a semiconductor device such as an LSI.
[0002]
[Prior art]
Since horizontal and vertical deformations of leads and the like formed in a semiconductor device such as an LSI hinder the mounting of the semiconductor device on a circuit board, the deformation is strictly inspected. In order to inspect the horizontal and vertical deformations of the leads and the like of the semiconductor device using the image recognition technique, it is necessary to image the semiconductor device from the upper surface and the side surface. In the case of imaging from the side, in the case of a flat package, it is necessary to take images from four sides, so there are problems that the number of cameras or the number of imaging increases, the inspection time increases, and the inspection equipment scale increases. Therefore, in order to eliminate the waste of inspection as described above, an inspection apparatus that inspects horizontal and vertical deformations of an inspection object by one imaging from one direction is disclosed in Japanese Patent Laid-Open Nos. 5-340733 and 2- This is disclosed in Japanese Patent No. 133883.
In the first prior art, as shown in a side view (a) and a plan view (b) in FIG. 4, a semiconductor device 31 to be inspected is placed on an inspection table 32 in which mirrors 35 are installed in all directions. If the camera 33 illuminates with the light source 36 and captures an image, a captured image as shown in FIG. 5 is obtained. With this configuration, in addition to the planar image F of the semiconductor device 31 in the captured image, the side image S reflected on the mirror 35 is simultaneously captured, and the horizontal and vertical deformation of the lead 34 is detected from one image. Can do.
The second prior art is not used for inspecting the lead of a semiconductor device and the like, and mainly aims to detect an uneven defect of a circuit board. As shown in FIG. 6, the inspection surface of the circuit board 38 is illuminated by a light source 39 from an oblique direction, and the inspection surface is imaged by a camera 40 disposed above the inspection surface. When the density distribution of the captured image parallel to the illumination direction by the light source 39 is measured as shown in FIG. 7A, a density change as shown in FIG. 7B is obtained. The maximum value of the portion exceeding the bright threshold value Sb and the minimum value of the portion smaller than the dark threshold value Sd are obtained, and the maximum value and the minimum value are found when these maximum values and minimum values are adjacent on the density distribution. The uneven defect 41 on the inspection surface is recognized from the difference from the value.
[0003]
[Problems to be solved by the invention]
However, although the presence or absence of the vertical deformation of the lead according to the first prior art can be detected, there is a problem that it is difficult to accurately detect the degree and position of the deformation. In addition, since the mirrors are arranged in the four directions, this becomes an obstacle for transporting the semiconductor device to the inspection position, and it is difficult to apply to a semiconductor device configured in a TAB (Tape Automated Bonding) format.
In addition, when the second prior art is applied to deformation inspection of a lead of a semiconductor device, it is possible to detect a defect accompanying an image with a sharp gradation change, such as unevenness, but a gentle bending in the vertical direction of the lead. However, it is difficult to detect without rapid change in image density, and it cannot be applied to deformation inspection of semiconductor leads.
An object of the present invention is to image a semiconductor device illuminated by oblique illumination from above and perform image processing on a grayscale image that is approximately proportional to the gradient from the horizontal plane. An object of the present invention is to provide a semiconductor device inspection method and apparatus for detecting deformation.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the method employed by the present invention is to image an illuminated semiconductor device with a camera from above, and from the obtained gray image, the degree of deformation of the semiconductor device and leads formed on the semiconductor device In the method for inspecting a semiconductor device, the curvature of the lead or the like is obtained by illuminating the semiconductor device from obliquely above the formation direction of the lead or the like and differentiating the grayscale image captured by the camera in the illumination direction. A semiconductor device inspection method comprising: determining whether the semiconductor device is acceptable or not by comparing the curvature with a predetermined reference value .
In order to achieve the above object, the means employed by the present invention is to take an image of an illuminated semiconductor device with a camera from above, and determine the degree of deformation of the semiconductor device and leads formed on the image from the taken gray image. In an inspection apparatus for a semiconductor device to be determined, an oblique illumination means for illuminating the semiconductor device from obliquely above in the formation direction of the leads and the like, and an image for differentiating the grayscale image in the same direction as the illumination direction by the oblique illumination means Processing means, comparison means for comparing the curvature of the lead or the like obtained by the differentiation process with a predetermined reference value, and pass / fail judgment means for judging pass / fail of the semiconductor device based on the comparison result. The semiconductor device inspection apparatus is characterized by the above.
Further, the semiconductor device inspection apparatus includes two light sources for the oblique illumination, and the directions of the two oblique illuminations are orthogonal to each other.
[0005]
[Action]
When a semiconductor device that is illuminated from an obliquely upward direction on an inspection surface that has a certain reflectivity and reflection directivity rather than a completely diffusing surface is imaged from above, the resulting grayscale image is in the direction projected on the inspection surface. A light and shade that is approximately proportional to the gradient from the horizontal direction of the inspection surface is shown. When the grayscale image is differentiated along the direction in which the illumination direction is projected onto the inspection surface, the change in light and shade is approximately proportional to the curvature along the direction in which the illumination direction of the inspection surface is projected onto the inspection surface. Therefore, by comparing this curvature with the reference value for pass / fail determination of the deformation inspection, the deformation inspection in the vertical direction such as the lead of the semiconductor device can be performed from the captured image from the vertical direction. Since the deformation in the horizontal direction can be detected from the grayscale image, the horizontal and vertical deformations of the lead and the like can be detected simultaneously from one image taken from above the semiconductor device.
In the inspection apparatus to which the inspection method is applied, a camera is disposed above a predetermined position on which a semiconductor device to be inspected is placed, and the semiconductor device is illuminated obliquely from above with oblique illumination means and imaged with the camera. . The grayscale image captured by the camera shows a grayscale that is approximately proportional to the gradient from the horizontal direction of the inspection surface along the direction in which the illumination direction is projected onto the inspection surface. Thus, the curvature of the shade change portion, that is, the deformation portion can be detected. By inputting the obtained curvature to the degree-of-deformation determination means and comparing it with a reference value for pass / fail determination of the deformation inspection, it is possible to perform a deformation inspection in the vertical direction such as a lead of the semiconductor device from a captured image from the vertical direction. . Since the deformation in the horizontal direction can be detected from the grayscale image, the horizontal and vertical deformations of the lead and the like can be detected simultaneously by placing the semiconductor device at the inspection position and taking one image with the camera. it can.
[0006]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention.
FIG. 1 is a schematic diagram showing the configuration of the semiconductor device inspection apparatus according to the first embodiment of the present invention, FIG. 2 is a plan view (a) and a side view (b) of the semiconductor device, and FIG. It is a schematic diagram which shows the illumination method in the inspection apparatus which concerns on an Example.
In FIG. 1, a semiconductor device inspection apparatus 1 according to the first embodiment is configured as a semiconductor device appearance inspection apparatus formed in a TAB format. The inspection apparatus 1 includes an inspection table 3 on which a device 2, which is a semiconductor device mounted on a tape 12, is placed at an inspection position, a CCD camera 4 disposed above the inspection table 3, and an inspection table 3. And a light source 5 that illuminates the device 2 from above, and an image processing device 6 that processes an image picked up by the CCD camera 4 and determines whether the appearance is acceptable.
[0007]
In the above configuration, the tape 12 on which the devices 2, 2... Are sequentially moved, the device 2 to be inspected is placed at a predetermined position on the inspection table 3, and the device 2 is illuminated with parallel light from the light source 5. The state is imaged by the CCD camera 4. The illumination direction by the light source 5 coincides with the formation direction (x direction) of the lead 2a formed on the device 2 as shown in FIG. Further, the imaging direction by the CCD camera 4 is also set so that the horizontal scanning line direction coincides with the x direction.
Since the horizontal plane of the device 2 is illuminated from an oblique direction and is imaged from the vertical direction, the grayscale image captured by the CCD camera 4 shows a grayscale that is approximately proportional to the gradient from the horizontal plane. The grayscale image is converted into an 8-bit (256 gradation) digital image by the A / D converter 7 and then stored in the image memory 8. This digital image is input to a differentiator (image processing means) 9, and the following expression (1) is calculated for the gray value B (i, j) of the pixel (i, j) for each horizontal scanning line, and the differential image is obtained. D (i, j) is determined.
D (i, j) = B (i + 1, j) -B (i, j) (1)
By differentiating the grayscale image along the x direction as described above, the change in the grayscale value is a change that approximates the curvature with which the horizontal plane of the device 2 is inclined from the x direction. This differential image D (i, j) is sent to a comparator ( comparing means ) 10 and compared with a preset threshold value ε to detect a portion where the curvature of the inspection surface is equal to or greater than a certain value and determiner ( pass / fail determination means). ) 11. The determination unit 11 performs pass / fail determination of each lead 2a or the entire device 2 and displays it.
[0008]
In the above configuration, only the deformation of the lead 2a along the x direction is detected. However, the deformation in the direction perpendicular to the x direction such as torsion of the lead 2a is also detected, and the lead 2a is deformed in four directions like a flat package. Next, a configuration in the case of inspecting a semiconductor device on which a semiconductor device or the like is formed will be described as a configuration of a second embodiment.
As shown in FIG. 3, in addition to the first light source 5a in the x direction, a second light source 5b in the y direction perpendicular to the x direction is disposed, and when the second light source 5a is illuminated, The device 13 when illuminated by the light source 5b is imaged by the CCD camera 4, two gray images are obtained, and image processing similar to that in the first embodiment is performed on both images, whereby x of the lead 13a is obtained. The deformation in the direction and y direction can be inspected. Also, with this configuration, it is possible to detect the deformation in the x direction and the y direction of the lead 13a in each forming direction in the inspection of the flat package type semiconductor device 13 in which leads and the like are formed on four sides.
In each of the above-described configurations, only detection of the deformation in the vertical direction of the leads 2a and 13a has been described. However, deformation in the horizontal plane can be easily performed by detecting the bending of the leads 2a and 13a from a predetermined direction from a grayscale image. Can be inspected. Further, not only the leads 2a and 13a but also the printing of the flatness of the package portion or the mark or the like can be detected from the grayscale image or the differential image.
In the configuration of the first embodiment, the x direction and the direction of the horizontal scanning line of the CCD camera 4 are made to coincide with each other. However, it is not always necessary to make them coincide with each other. You can also set the direction.
[0009]
【The invention's effect】
As described above, according to the present invention, when a semiconductor device illuminated from an obliquely upward direction on an inspection surface having a certain reflectance and reflection directivity rather than a complete diffusion surface is imaged from above, a gray-scale image obtained is obtained. Indicates shades approximately proportional to the gradient from the horizontal direction of the inspection surface along the direction in which the illumination direction is projected onto the inspection surface. When the grayscale image is differentiated along the direction in which the illumination direction is projected onto the inspection surface, the change in light and shade is approximately proportional to the curvature along the direction in which the illumination direction of the inspection surface is projected onto the inspection surface. Therefore, by comparing this curvature with the reference value for pass / fail determination of the deformation inspection, the deformation inspection in the vertical direction such as the lead of the semiconductor device can be performed from the captured image from the vertical direction. Since the deformation in the horizontal direction can be detected from the grayscale image, the horizontal and vertical deformations of the lead and the like can be detected simultaneously from one image taken from above the semiconductor device.
In the inspection apparatus to which the inspection method is applied, a camera is disposed above a predetermined position on which a semiconductor device to be inspected is placed, and the semiconductor device is illuminated obliquely from above with oblique illumination means and imaged with the camera. . The grayscale image captured by the camera shows a grayscale that is approximately proportional to the gradient from the horizontal direction of the inspection surface along the direction in which the illumination direction is projected onto the inspection surface. Thus, the curvature of the shade change portion, that is, the deformation portion can be detected. By inputting the obtained curvature to the degree-of-deformation determination means and comparing it with a reference value for pass / fail determination of the deformation inspection, it is possible to perform a deformation inspection in the vertical direction such as a lead of the semiconductor device from a captured image from the vertical direction. . Since the deformation in the horizontal direction can be detected from the grayscale image, the horizontal and vertical deformations of the lead and the like can be detected simultaneously by placing the semiconductor device at the inspection position and taking one image with the camera. it can.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of a semiconductor device inspection apparatus according to a first embodiment of the present invention.
FIG. 2 is a side view of the semiconductor device according to the example.
FIG. 3 is a schematic view showing a method for illuminating a semiconductor device according to a second embodiment.
4A and 4B are a side view and a plan view showing a configuration of an inspection apparatus according to a conventional example.
FIG. 5 is a diagram of a captured image having the same configuration as above.
FIG. 6 is a schematic diagram showing a configuration of an inspection apparatus according to a conventional example.
FIG. 7 is an inspection direction and a shading change graph according to the same configuration.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inspection apparatus 2, 13 ... Device (semiconductor device)
4 ... CCD camera 5 ... Light source 6 ... Image processing device 9 ... Differentiator (image processing means)
10: Comparator (deformation degree judging means)

Claims (3)

In an inspection method for a semiconductor device in which an illuminated semiconductor device is imaged by a camera from above and the degree of deformation of the semiconductor device or leads formed on the semiconductor device is determined from the captured grayscale image.
The semiconductor device is illuminated obliquely from above in the formation direction of the lead, etc., and the curvature of the lead is obtained by differentiating the grayscale image captured by the camera in the illumination direction, and the curvature and a predetermined reference value are obtained. A method for inspecting a semiconductor device, comprising: determining whether the semiconductor device is acceptable by comparing the results . In an inspection apparatus for a semiconductor device, the illuminated semiconductor device is imaged by a camera from above, and the degree of deformation of the semiconductor device or leads formed on the semiconductor device is determined from the captured grayscale image.
Oblique illumination means for illuminating the semiconductor device from obliquely above the formation direction of the leads,
Image processing means for differentiating the grayscale image in the same direction as the illumination direction by the oblique illumination means;
A comparison means for comparing the curvature of the lead or the like obtained by the differentiation process with a predetermined reference value;
An inspection apparatus for a semiconductor device, comprising: pass / fail determination means for determining whether the semiconductor device is acceptable based on the comparison result . The inspection apparatus for a semiconductor device according to claim 2, comprising two oblique illumination light sources, and the two oblique illumination directions are orthogonal to each other.

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