JPH08219740A - Method and equipment for inspecting semiconductor device - Google Patents

Abstract

PURPOSE: To obtain method and equipment for inspecting a semiconductor device in which deformation of lead or the like of the semiconductor device is detected by processing a light- and-shade image thereof picked up from the upper part. CONSTITUTION: A semiconductor device 2 is illuminated by a light source 5 disposed obliquely above the lead or the like formed on the semiconductor device 2, and picked-up by a camera 4 disposed above the device 2. A light-and-shade image thus obtained is then subjected to differentiation in the direction of illumination by means of an image processor 6 and the extent of deformation is determined based on the variation in the light-and-shade level obtained through differentiation. The light-and-shade image has light-and-shade level approximately proportional to the gradient from the horizontal direction and the light-and-shade level obtained through differentiation is approximately proportional to the curvature of the plane to be inspected. Consequently, deformation of the lead or the like of semiconductor device can be detected by comparing the curvature with a reference value for deciding pass/fail of deformation test. Since deformation in the horizontal direction can be detected on the light-and-shade image, deformation of the lead or the like can be detected simultaneously in horizontal and vertical directions from one image of the semiconductor device picked up from the upper part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device inspection method and device for inspecting harmful deformation of leads and the like formed on a semiconductor device such as an LSI.

[0002]

2. Description of the Related Art Deformation of leads and the like formed on a semiconductor device such as an LSI in the horizontal and vertical directions becomes a hindrance when mounting the semiconductor device on a circuit board. Therefore, the deformation is strictly inspected. In order to inspect horizontal and vertical deformations of leads and the like of a semiconductor device by using an image recognition technique, it is necessary to image the semiconductor device from the top and side surfaces. In the case of a flat package such as a flat package, it is necessary to pick up images from four sides, which increases the number of cameras or the number of images, which increases the inspection time and the inspection equipment scale. Therefore, in order to eliminate the waste of the inspection as described above, an inspection device for inspecting the deformation of the inspection object in the horizontal and vertical directions by one-time imaging from one direction is disclosed in JP-A-5-340733 and JP-A-2-34073. 133883
No. 6,086,045. The above-mentioned first conventional technique is shown in FIG.
As shown in a side view (a) and a plan view (b), a semiconductor device 31 to be inspected is placed on an inspection table 32 in which mirrors 35 are installed on all sides, and a camera 33 is illuminated by a light source 36. When the image is picked up, the picked-up image as shown in FIG. 5 is obtained. With this configuration, in addition to the plane image F of the semiconductor device 31 in the picked-up image, the side image S reflected on the mirror 35 is simultaneously captured, and the deformation of the leads 34 in the horizontal and vertical directions can be detected from one image. You can The second conventional technique is not used for inspecting the leads of a semiconductor device or the like, and its purpose is mainly to detect irregularities in a circuit board. As shown in FIG. 6, the inspection surface of the circuit board 38 is illuminated by the light source 39 from an oblique direction, and the inspection surface is imaged by the camera 40 arranged above the inspection surface. When the density distribution parallel to the illumination direction of the light source 39 of this captured image is measured as shown in FIG. 7 (a), the density change shown in FIG. 7 (b) is obtained. Brighter threshold S
The maximum value of the portion exceeding b and the minimum value of the portion smaller than the darker threshold Sd are obtained, and when these maximum value and minimum value are adjacent to each other on the density distribution, the difference between the maximum value and the minimum value Thus, the uneven defect 41 on the inspection surface is recognized.

[0003]

However, although the presence or absence of the vertical deformation of the lead according to the first prior art can be detected, it is difficult to accurately detect the degree of deformation and the position thereof. There was a point. In addition, since the mirrors are arranged on all sides, this becomes an obstacle for transporting the semiconductor device to the inspection position, and particularly TAB (Tape Automat).
It is difficult to apply to a semiconductor device configured in the ed bonding) format. When the second conventional technique is applied to a deformation inspection of a lead of a semiconductor device, it is possible to detect a defect such as a concavo-convex accompanied by an abrupt gradation change in the image, but the lead is bent gently in the vertical direction. However, it is difficult to detect images without abrupt changes in light and shade, and there is a problem that they cannot be applied to deformation inspection of semiconductor leads. An object of the present invention is to capture an image of a semiconductor device illuminated by oblique illumination from above and perform image processing of a grayscale image approximately proportional to a gradient from a horizontal plane. An object of the present invention is to provide a semiconductor device inspection method and device for detecting deformation.

[0004]

In order to achieve the above object, a method adopted by the present invention is to take an image of an illuminated semiconductor device from above with a camera, and select the semiconductor device or the semiconductor device from the grayscale image taken. In a method of inspecting a semiconductor device for determining the degree of deformation of a formed lead or the like, the semiconductor device is illuminated from obliquely above the formation direction of the lead or the like, and a grayscale image captured by the camera is differentiated in the illumination direction. The semiconductor device inspection method is characterized in that the degree of deformation is determined based on the density change subjected to the differential processing. Further, the means adopted by the present invention is a semiconductor device in which an illuminated semiconductor device is imaged from above by a camera and the degree of deformation of the semiconductor device or leads formed on the semiconductor device is determined from the captured grayscale image. In the inspection apparatus, oblique illumination means for illuminating the semiconductor device from obliquely above the formation direction of the leads and the like, image processing means for differentiating the grayscale image in the same direction as the illumination direction by the oblique illumination means, An inspection apparatus for a semiconductor device is provided, which comprises: a deformation degree determination unit that determines the deformation degree based on a density change of an image subjected to the differential processing.

[0005]

When a semiconductor device illuminated from an obliquely upper direction is imaged from above on an inspection surface having a constant reflectance and reflection directivity instead of a perfect diffusion surface, the obtained grayscale image is projected on the inspection surface. A shade that is approximately proportional to the gradient of the inspection surface from the horizontal direction is shown along the direction. When the grayscale image is differentiated along the direction in which the illumination direction is projected on the inspection surface, the change in the grayscale is approximately proportional to the curvature along the direction in which the illumination direction on the inspection surface is projected on the inspection surface. Therefore, by comparing this curvature with the reference value of the pass / fail judgment of the deformation inspection, the deformation inspection of the leads of the semiconductor device in the vertical direction can be performed from the imaged image from the vertical direction. Since the horizontal deformation can be detected from the grayscale image, the horizontal and vertical deformations of the leads and the like can be simultaneously detected from one image taken from above the semiconductor device. In an inspection apparatus to which the above inspection method is applied, a camera is arranged above a predetermined position on which a semiconductor device to be inspected is mounted, the semiconductor device is illuminated obliquely from above by an oblique illumination means, and an image is captured by 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 on the inspection surface. By this, the curvature of the shade change part, that is, the curvature of the deformed part can be detected.
By inputting the obtained curvature to the deformation degree judging means and comparing it with the reference value of the pass / fail judgment of the deformation inspection, the deformation inspection of the leads of the semiconductor device in the vertical direction can be performed from the imaged image from the vertical direction. . Since the deformation in the horizontal direction can be detected from the grayscale image, the deformation in the horizontal and vertical directions of the lead or the like can be detected at the same time by placing the semiconductor device at the inspection position and taking a single image with the camera. it can.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. still,
The following example is an example embodying the present invention and does not limit the technical scope of the present invention. Figure 1
1 is a schematic diagram showing the configuration of a 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. 3 is an inspection according to the second embodiment. It is a schematic diagram which shows the illumination method in an apparatus. 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 for mounting a device 2 which is a semiconductor device mounted on a tape 12 at an inspection position,
A CCD camera 4 arranged above the inspection table 3 and a light source 5 for illuminating the device 2 on the inspection table 3 obliquely from above.
And an image processing device 6 for processing the image picked up by the CCD camera 4 to judge whether the appearance state is acceptable or not.

In the above structure, the tape 12 on which the devices 2, 2 ... Are mounted is sequentially moved to place the device 2 to be inspected at a predetermined position on the inspection table 3, and the device 2 is irradiated with parallel light from the light source 5. The CCD camera 4 takes an image of the illuminated state. The illuminating direction of the light source 5 coincides with the forming direction (x direction) of the lead 2a formed on the device 2 as shown in FIG. 2, and is irradiated obliquely from above. The image pickup direction of 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 obliquely and is imaged from the vertical direction, the grayscale image captured by the CCD camera 4 exhibits a grayscale approximately proportional to the gradient from the horizontal plane. This grayscale image is converted to 8 by the A / D converter 7.
After being converted to a bit (256 gradation) digital image,
It is stored in the image memory 8. This digital image is input to the differentiator (image processing means) 9, and the following equation (1) is calculated for the grayscale value B (i, j) of the pixel (i, j) for each horizontal scanning line to obtain the differential image. D (i, j) is obtained. 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 of the grayscale value is changed in the horizontal plane of the device 2. Is a change similar to the curvature inclined from the x direction. This differential image D
(I, j) is sent to the comparator (deformation degree determination means) 10,
The threshold value ε set in advance is compared, and the location where the curvature of the inspection surface is a certain value or more is detected and sent to the determiner 11. The judging device 11 judges whether each lead 2a or the entire device 2 is acceptable, and displays it.

In the above structure, only the deformation of the lead 2a along the x direction is detected. However, the deformation of the lead 2a in the direction orthogonal to the x direction such as the twisting of the lead 2a is also detected, and like the flat package. Next, a structure for inspecting a semiconductor device having leads and the like formed on all sides will be described as a structure 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 orthogonal to the x-direction is provided to illuminate with the first light source 5a, The CCD 13 captures an image of the device 13 when it is illuminated by the light source 5b, obtains two grayscale images, and performs image processing similar to that of the first embodiment on both of the grayscale images. Direction and y
Directional deformations can be inspected. With this configuration, the semiconductor device 13 of the flat package type in which leads and the like are formed on all sides is inspected for the leads 13a in each forming direction.
Can be detected in the x-direction and the y-direction, respectively. In each of the above-mentioned configurations, only the detection of the vertical deformation of the leads 2a and 13a is described, but the deformation in the horizontal plane can be easily performed by detecting the bending of the leads 2a and 13a from the predetermined direction from the grayscale image. Can be inspected. Further, not only the leads 2a and 13a but also the flatness of the package portion or the printing of marks or the like can be detected from the grayscale image or the differential image. or,
In the configuration of the first embodiment described above, the x direction and the direction of the horizontal scanning line of the CCD camera 4 are made to coincide with each other, but it is not always necessary to make them coincide with each other, and if the complexity of the differential processing is not a problem, the direction may be any direction. It can also be set.

[0009]

As described above, according to the present invention, when a semiconductor device illuminated from an obliquely upper direction on an inspection surface having a constant reflectance and a reflection directivity instead of a perfect diffusion surface is imaged from above, The obtained grayscale image shows a grayscale approximately proportional to the gradient from the horizontal direction of the inspection surface along the direction in which the illumination direction is projected on the inspection surface. When the grayscale image is differentiated along the direction in which the illumination direction is projected on the inspection surface, the change in the grayscale is approximately proportional to the curvature along the direction in which the illumination direction on the inspection surface is projected on the inspection surface. Therefore, by comparing this curvature with the reference value of the pass / fail judgment of the deformation inspection, the deformation inspection of the leads of the semiconductor device in the vertical direction can be performed from the imaged image from the vertical direction. Since the horizontal deformation can be detected from the grayscale image, the horizontal and vertical deformations of the leads and the like can be simultaneously detected from one image taken from above the semiconductor device. In an inspection apparatus to which the above inspection method is applied, a camera is arranged above a predetermined position on which a semiconductor device to be inspected is mounted, the semiconductor device is illuminated obliquely from above by an oblique illumination means, and an image is captured by 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 on the inspection surface. By this, the curvature of the shade change part, that is, the curvature of the deformed part can be detected. By inputting the obtained curvature to the deformation degree judging means and comparing it with the reference value of the pass / fail judgment of the deformation inspection, the deformation inspection of the leads of the semiconductor device in the vertical direction can be performed from the imaged image from the vertical direction. . Since the deformation in the horizontal direction can be detected from the grayscale image, the deformation in the horizontal and vertical directions of the lead or the like can be detected at the same time by placing the semiconductor device at the inspection position and taking a single image with the camera. it can.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the 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 diagram showing a lighting method of a semiconductor device according to a second embodiment.

FIG. 4 is a side view (a) and a plan view (b) showing a configuration of an inspection device according to a conventional example.

FIG. 5 is a diagram of a captured image according to the above configuration.

FIG. 6 is a schematic diagram showing a configuration of an inspection device according to a conventional example.

FIG. 7 is a graph showing the inspection direction and its grayscale change according to the above configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inspection device 2, 13 ... Device (semiconductor device) 4 ... CCD camera 5 ... Light source 6 ... Image processing device 9 ... Differentiator (image processing means) 10 ... Comparator (deformation degree determination means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatoshi Fujimoto 2-3-3 Higashidokorozawa Wada, Tokorozawa-shi, Saitama MM Building 3F Genesis Technology Co., Ltd. (72) Inventor Yoshiro Nishimoto Takatsukadai, Nishi-ku, Kobe-shi, Hyogo 1-5-5 Kobe Steel Co., Ltd., Kobe Research Institute (72) Inventor Yuichiro Goto 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel Works, Kobe Research Institute (72) Inventor Eiji Takahashi 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Co., Ltd. Kobe Research Institute (72) Inventor Yamaguchi certificate 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe, Inc. Steel Works Kobe Research Institute (72) Inventor Katsumi Yasuda 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Stock Association Kobe Steel, Kobe Technology in the Laboratory (72) inventor Nakayama ten thousand Kishi, Kobe City, Hyogo Prefecture, Nishi-ku, Takatsukadai 1-chome 5th Kobe Steel, No. 5 Co., Ltd. Kobe comprehensive technology within the Institute

Claims (2)

[Claims] 1. A method of inspecting a semiconductor device, wherein an illuminated semiconductor device is imaged from above by a camera, and the degree of deformation of the semiconductor device or leads formed on the semiconductor device is determined from the imaged gray-scale image. The semiconductor device is illuminated from obliquely above the formation direction of the leads, the grayscale image captured by the camera is differentiated in the illumination direction, and the deformation degree is determined based on the differentiated density change. Semiconductor device inspection method. 2. An inspection apparatus for a semiconductor device, wherein an illuminated semiconductor device is imaged from above by a camera, 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 lighting means, and deformation degree judging means for judging the deformation degree based on the density change of the differentiated image are provided. A semiconductor device inspection apparatus characterized by the following.