JPH11281337A - Defect inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high speed inspection of a plurality of members under test at once for defects such as cracks and breaks of the edges of the members by rotating the members at the same time and radiating an inspecting light on their edges in bloc. SOLUTION: A plurality of disc-like members 1 under test such as semiconductor wafers are supported coaxially by a support shaft 2, it is rotated by rotating means 3 such as a motor, an inspection light radiating means 5 radiates an inspection light 4 on the edge 1a of the member 1, a scattering light detecting means 7 detects a scattered light 6 at the irradiated edge 1a, a defect inspecting means 8 inspect the defects of the edge 1a of the member 1 under test, based on the irradiating position of the inspecting light 4 and intensity of the scattered light 6. This method enables quick defect inspection of the cracks, breaks, etc., of the edge 1a of the member 1 under test and avoidance of the yield reduction due to the defects of the edges 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus, and more particularly, to a defect inspection apparatus used for inspecting the appearance of a semiconductor wafer or the like.

[0002]

2. Description of the Related Art In recent semiconductor devices in which the minimum line width of a circuit has become extremely small, the size of a defect that reduces the yield of products has become extremely small. Many of these defects are caused by dust adhering to semiconductor wafers and the like. It is difficult to visually inspect the minute defect. For this reason, various types of defect inspection apparatuses for inspecting the appearance of semiconductor wafers using high-brightness parallel rays or laser beams have been put to practical use. For example, as shown in FIG. 18, when a member to be inspected 41 such as a semiconductor wafer having a mirror surface characteristic is irradiated with a high-brightness parallel light beam or the like, the irradiated light beam 42 is reflected at the same angle as the incident angle in a portion where no defect exists. On the other hand, the light is scattered in a direction different from the regular reflection angle (scattered light 44) in the portion where the defect exists (specular reflection light 43). The defect inspection device using the scattering at the above-mentioned defect is described in Pedro Kilienfeld; Aerosol
Science Technology 5: pp. 145-165 (1986). FIG. 19 shows one of the device configurations described in the above document. The defect inspection apparatus shown in FIG. 19 performs a high-speed appearance inspection of a semiconductor wafer by scanning a semiconductor wafer with a laser beam. In the defect inspection apparatus, the light beam 52 emitted from the laser light source 51
a and 53b and the lenses 54a and 54b to enter the rotating polygon mirror 55. The rotating polygon mirror 55 rotates at a predetermined angular velocity, and scans the light beam 52 on the semiconductor wafer 56. The light beam 52 applied to a portion of the semiconductor wafer 56 where no defect exists is specularly reflected, but is scattered in a portion where the defect exists in a direction different from the regular reflection angle. The scattered light 57 is detected by scattered light detecting means 58 including a photomultiplier tube 58a, and a defect inspection is performed. Since the scattered light detecting means 58 is arranged so that the specularly reflected light rays 59 do not directly enter, the portion where a defect exists is detected brighter than the portion where no defect exists.

[0003]

However, the edge portion of the semiconductor wafer is more likely to be chipped or adhered to dust at the time of handling and the like than in other places, and particles on the edge portion cause defects on the surface of the semiconductor wafer. May be triggered. In addition, cracks and the like may occur, and it is important to inspect the edge portion of the semiconductor wafer from the viewpoint of improving the product yield. However, the above-described defect inspection apparatus aims at detecting a defect existing on the surface of a semiconductor wafer, and cannot inspect a defect at an edge portion of the semiconductor wafer at a high speed. The present invention
In order to solve such problems in the conventional technology,
It is an object of the present invention to improve a defect inspection apparatus and to provide a defect inspection apparatus capable of simultaneously detecting a plurality of edge portions of a semiconductor wafer or the like in a short time.

[0004]

In order to achieve the above object, the present invention provides a support shaft capable of supporting a plurality of disk-shaped members to be inspected coaxially, and a method of driving the support shaft to drive the member to be inspected. Rotating means for rotating the member, inspection light irradiating means for irradiating inspection light on the edge of the member to be inspected rotated by the rotating means, and irradiating the edge of the member to be inspected by the inspection light irradiating means Scattered light detection means for detecting scattered scattered light; and defect inspection means for inspecting a defect at an edge portion of the inspected member based on the irradiation position of the inspection light and the intensity of the scattered light. It is configured as a defect inspection device. In the above defect inspection apparatus, since a plurality of inspected members are simultaneously rotated and the inspection light is radiated to the edge portions of the inspected members at once, defect inspection such as cracks and chips at the edge portions of the inspected members is performed. Can be inspected simultaneously at high speed. In the defect inspection apparatus, in order to irradiate a plurality of inspected members with inspection light in a lump, the inspection light irradiating means applies, for example, slit light along the support shaft to the plurality of inspected members. What is irradiated may be used. At this time, the scattered light detecting means is provided for each of the inspected members supported by the support shaft. In this case, since the slit light is incident on the same position of the plurality of inspected members at the same angle, it is possible to inspect the edge portions of each inspected member in parallel. Further, a light shielding plate may be provided between each scattered light detecting means in order to eliminate the influence of the scattering from the adjacent inspected member. In order to inspect the edge portions of the plurality of inspected members in parallel, the inspection light irradiating means may be one that sequentially scans the spot light on the plurality of inspected members. In this case, since the scanning position of the spot light can be specified, it is not necessary to provide the scattered light detecting means for each inspected member to be inspected. The member to be inspected is, for example, a semiconductor wafer.

In the defect inspection apparatus, the scattered light detection means may be one which captures a two-dimensional image of the surface of the edge in the rotation direction and the thickness direction of the member to be inspected. In this case, it is possible to inspect in more detail which part of the edge of the inspected member has a defect, and furthermore, the shape of the defect can be used as a reference for the defect inspection, and the accuracy of the defect inspection can be improved. Can be improved. In order to capture the two-dimensional image, for example, a CCD camera having an imaging range of at least the thickness of the edge portion of the inspected member may be used as the scattered light detection unit. The two-dimensional image is captured by providing, for example, scattered light detection means for detecting scattered light scattered from one point of the edge portion so as to be movable in the thickness direction of the edge portion of the inspected member. It is also possible. In the defect inspection apparatus, the scattered light scattered at the edge of the inspected member can be guided to the scattered light detection means by, for example, an optical fiber. It is also possible to guide using a lens and a mirror.
Further, by providing the light incident portion of the optical fiber on each of the front surface side and the back surface side of the edge portion of the inspected member, the edge portion of the inspected member can be inspected in more detail. Also, in the above defect inspection apparatus,
A case where the defect inspection unit inspects the defect of the inspection target member based on a composite image obtained by synthesizing the images of the surface of the edge portion of the plurality of inspection target members captured by the scattered light detection unit; Thus, it is possible to perform an accurate and comprehensive inspection based on the correlation between the defects of the inspected members. In the defect inspection apparatus, when the defect inspection means inspects a defect of a wafer by comparing images of the surface of an edge portion of a plurality of wafers imaged by the scattered light detection means with each other, For example, the two captured images selected from the respective captured images are aligned, a difference image including a difference between pixels of the two aligned captured images is generated, and the difference image is determined by a predetermined threshold. By performing the evaluation using the values, it is possible to perform an accurate inspection based on the correlation of each wafer.

According to another aspect of the present invention, there is provided a mounting means for mounting a plurality of wafers each having an inclined surface on an outer peripheral end, and a corresponding inclined surface of each wafer mounted on the mounting means is a predetermined line. Positioning means for positioning the mounting means so as to include: a rotating means for driving the mounting means positioned by the positioning means to rotate the wafer; and an inclined surface of each wafer rotated by the rotating means. And a defect inspection device that performs image processing on the image of the inclined surface of each wafer captured by the imaging device and inspects for defects. . According to the defect inspection apparatus according to the other aspect of the invention, since the mounting means is positioned by the positioning means so that the corresponding inclined surface of each wafer includes a predetermined line, even when the inclined surface is provided on the wafer. The imaging means can collectively image the inclined surfaces of a plurality of wafers, and the inspection can be performed quickly. Further, in the above-described defect inspection apparatus, since the imaging means is provided for each of the front surface and the back surface of the wafer, the front surface and the back surface of the wafer can be simultaneously inspected. it can. In the defect inspection apparatus, the defect inspection unit may perform, for example, alignment of two images selected from images of each wafer based on the images of the plurality of wafers captured by the imaging unit, If a wafer defect is to be inspected by generating a difference image consisting of the absolute value of the difference between the pixels of the two aligned images and evaluating the difference image using a predetermined threshold value In addition, the inspection can be performed quickly, and an accurate inspection can be performed based on the correlation of each wafer.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
It should be noted that the following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention. FIG. 1 is a diagram showing a schematic configuration of a defect inspection apparatus according to one embodiment of the present invention. As shown in FIG.
The defect inspection apparatus 0 according to the present embodiment includes a support shaft 2 capable of coaxially supporting a plurality of disk-shaped inspected members 1 such as semiconductor wafers, and the above-described inspection system by driving the support shaft 2. A rotating means 3 such as a motor for rotating the member 1, and an edge 1a of the inspected member 1 rotated by the rotating means 3;
Inspection light irradiating means 5 for irradiating the inspection light 4 with the inspection light 4;
And a defect inspection means 8 for inspecting a defect of the edge portion 1a of the inspected member 1 based on the irradiation position of the inspection light 4 and the intensity of the scattered light 6.

In the defect inspection apparatus 0, a plurality of inspected members 1 such as semiconductor wafers are stored in a wafer cassette 9 at the same time. The edges 1a of the plurality of inspected members 1 stored in the wafer cassette 9 are collectively irradiated with light beams by the inspection light irradiating means 5 provided outside the wafer cassette 9. The inspection light irradiating means 5 includes a laser light source 5a and a cylindrical lens 5c for shaping a light beam 5b from the laser light source 5a into slit light (inspection light) 4.
And irradiates the same position of each inspected member 1 with the slit light 4 at the same angle. At a portion where there is no defect in the edge portion 1a, the slit light 4 is specularly reflected at the same angle as the incident angle. Above the wafer cassette 9, a scattered light detecting means 7 such as a silicon photodiode for detecting scattered light 6 from the edge 1a of the member 1 to be inspected is provided. The silicon photodiode has features of high sensitivity to visible light, small size, and low cost, and is suitable for the scattered light detection means 7 because it can directly detect a current proportional to the amount of received light. Note that the scattered light detecting means 7 detects the specularly reflected light 1 from the edge 1a of the inspected member 1.
0 is arranged at a position where it does not directly enter. Further, the scattered light detecting means 7 is spatially divided, and has a structure in which scattered light 6 from each inspected member 1 is received by a separate detector. Further, a light-shielding plate 11 is provided between the detectors in order to eliminate the influence of scattered light from the member 1 to be inspected. The scattered light detecting means 7
Is connected to a defect inspection means 8 such as a computer via a signal processing circuit 12. In addition, the wafer cassette 9
A support shaft 2 for coaxially supporting a plurality of stored inspected members 1 is provided at a lower portion of the support member 2. A rotating means 3 such as a motor is connected to the support shaft 2 so that the inspection target member 1 can be rotated in a predetermined direction and at a predetermined speed. The rotating means 3 is connected to and controlled by the defect inspection means 8 via a motor driver 13. The rotating means 3 is rotated by the control signal from the defect inspecting means 8, and the plurality of inspected members 1 in the wafer cassette 9 are simultaneously rotated.

The signal from the scattered light detection means 7 is taken into the defect inspection means 8 and the calculation result is output to a monitor 8a. FIG. 2 is a diagram showing an output example of the defect inspection apparatus 0 obtained for a certain inspection target member 1. The horizontal axis indicates time, and the vertical axis indicates scattered light intensity. Since the signal in FIG. 2 is a signal captured while rotating the member 1 to be inspected, the horizontal axis (time axis) is
This corresponds to the rotation angle of the member 1 to be inspected. Therefore, by detecting the increased portion of the scattered light 6, it is possible to perform an inspection including the presence / absence and position of a defect at the edge 1 a of the inspected member 1. The determination as to whether or not there is a defect is made based on, for example, whether or not the intensity of the scattered light 6 exceeds a predetermined threshold Th. In the defect inspection apparatus 0, since an output as shown in FIG. 2 is obtained simultaneously for all the inspected members 1 stored in the wafer cassette 9, a batch high-speed inspection of the edge 1a of the inspected member 1 is performed. It is possible to do.

[0010]

In the above embodiment, the defect inspection at the edge 1a of the inspected member 1 was performed at once by the slit light 4. However, as shown in FIG.
By scanning the spot light from the scanning polygon mirror 5e with the rotating polygon mirror 5e, it is also possible to collectively perform the defect inspection on the plurality of inspected members 1 stored in the wafer cassette 9. In this case, since the irradiation position of the laser can be identified by detecting the rotation angle of the rotating polygon mirror 5e, it is not necessary to provide the scattered light detection means 7 for each inspection target member 1. Further, in the above embodiment, a semiconductor wafer is used as the inspection target member 1. However, another disk-like inspection target member such as a magnetic disk may be used. Further, in the above embodiment, the light-shielding plate 11 is provided between the detectors in order to eliminate the influence of the scattered light from the member 1 to be inspected, but the present invention is not limited to this. The influence of the scattered light from the adjacent inspected member 1 may be eliminated by approaching the inspected member 1 or the like. Such a defect inspection device is also an example of the defect inspection device in the present invention.

In the above-described embodiment, a silicon photodiode is used for the scattered light detecting means 7. Instead, the edge portion 1a in the rotation direction and the thickness direction of the member 1 to be inspected is used.
For example, an image pickup means such as a CCD camera for picking up a two-dimensional image may be used. FIG. 4 shows an example of a defect inspection apparatus using the above-mentioned imaging means. 4 differs from the defect inspection apparatus 0 according to the above-described embodiment in that the scattered light is scattered by the edge portions 1a of the plurality of inspected members 1 and the scattered light is respectively transmitted by the optical fibers 14. The portion is guided and imaged by the imaging means 7 'such as a CCD camera, and the other portions have substantially the same configuration. In the defect inspection apparatus 0 ', optical fibers 14 are provided on the front surface and the back surface of each inspection target member 1, respectively. This is because, as shown in FIG. 5A, the edge 1a of the member 1 to be inspected whose thickness central portion protrudes from the surface is inspected in detail. The light incident portion 14a of each optical fiber 14 is provided close to the front surface or the back surface of the edge portion 1a, and is arranged so that the scattered light scattered on the front surface or the back surface of the edge portion 1a is incident. I have. The images of the edge 1a of each member 1 to be inspected guided by the optical fiber are combined by the lens 15 and then
For example, the image is captured by an imaging unit 7 'such as a CCD camera. Of course, it is also possible to provide an image pickup means 7 'such as a CCD camera for each optical fiber 14 and to pick up images transmitted by each optical fiber 14 by separate image pickup means. In consideration of miniaturization and the like, imaging of a plurality of inspected members 1 is performed by a single imaging unit 7 '. The imaging means 7 '
The CCD camera used for the inspection is at least
Pixels corresponding to the thickness of the edge portion 1a are arranged, and an image of the edge portion 1a of the inspected member 1 at a certain rotational position can be captured at a time. And the support shaft 2
By rotating the member 1 to be inspected by the rotating means 3, an image of the edge portion 1a can be obtained for the entire periphery of the member 1 to be inspected. Here, FIG. 5B is an example of an image of the edge portion 1a imaged by the imaging means 7 '.

An example of the image shown in FIG. 5B is obtained by combining the images scattered on the front and back surfaces of the three inspected members 1A, 1B, and 1C by the lens 15 before the image pickup means. 7 ′. In the composite image, the images of the inspected members 1A, 1B, and 1C are arranged in rows, and the images of the front and back edges 1a are arranged in columns. In the composite image, a bright portion is a chamfered portion in the edge portion 1a. For example, the image on the back side of the inspected member 1A includes
A part of the chamfered part has a dark part, but this part shows a defect such as chipping. The composite image captured by the imaging unit 7 ′ is supplied to the defect inspection unit 8 via the signal processing circuit 12. In the defect inspection means 8, for example, it is determined by image processing whether a dark portion exists in a bright portion of the chamfered portion, and inspection is performed on the front surface and the back surface of the edge portion 1a of each inspected member 1. The defect inspection by the image processing is performed, for example, by setting a predetermined threshold value for the brightness of the chamfered portion of the image and binarizing the image with the threshold value. In addition, it is also possible to perform a defect inspection using a difference image from a normal image having no defect. Further, when a pattern appearing in the image is known in advance, such as a chamfered portion, it is possible to perform a defect inspection by comparing the image with other inspected members 1 and parts included in the composite image. . As compared with the images of the other inspected members 1, the existence of the defect becomes clearer, and the inspection error can be reduced. In addition, for example, by comparing with the shape of a defect included in a previously prepared image,
It is also possible to determine the type of a defect such as a crack. As described above, according to the defect inspection apparatus 0 ′, details such as specifying where in the thickness direction of the edge portion 1a a defect exists, specifying the shape of the defect, and the like are based on the captured image. It is possible to perform a defect inspection. In the defect inspection apparatus 0 ', the C used for the imaging means 7'
If the number of pixels of the CD camera becomes smaller than the thickness of the inspection target member 1 due to the relationship with the measurement accuracy, the light incident portion 14a of the optical fiber 14 movably provided is connected to the inspection target member 1.
Inspection can be performed by scanning in the thickness direction of the target and capturing a plurality of images of the part. Also,
As shown in FIG. 6, instead of the optical fiber 14, a relay lens optical system in which a lens 16 and a mirror 17 are arranged for each inspection target member 1 can be used. As the inspection light irradiating means 5 in the defect inspection apparatus 0 ', a planar light source may be used as in the above embodiment, or a laser light source 5d and a rotating polygon mirror 5e as shown in FIG. May be used. Edge 1a of inspected member 1
In order to irradiate the inspection light to the front surface and the back surface, respectively, as shown in FIG. 7, for example, a laser light source 5d and a rotating polygon mirror 5e may be provided for the front surface and the back surface, respectively.
Such a defect inspection device is also an example of the defect inspection device in the present invention.

Here, FIGS. 8 and 9 show a specific configuration example of a defect inspection apparatus for inspecting a defect by comparing an image of a certain inspected member 1 with an image of another inspected member 1. FIG. FIG. 9A is a side view of the sensor unit provided in the defect inspection apparatus, and FIG. 9B is a front view of the sensor unit provided in the defect apparatus. As shown in FIGS. 8 and 9, the defect inspection apparatus 0 ″ includes a support shaft 2 capable of coaxially supporting a plurality of wafers (one example of a member to be inspected) 1 ′ stored in a wafer cassette 18; By driving the support shaft 2, the wafer 1 '
Rotating means 3 such as a motor for rotating the
LED array for irradiating the inspection light to the edge 1a of the wafer 1 'rotated by the laser (corresponding to the inspection light irradiation means)
5 ′ and a line CC for detecting the scattered light emitted to the edge 1a of the wafer 1 ′ by the illumination LED array 5 ′.
A sensor unit 19 having a D sensor (corresponding to scattered light detection means) 7 ″, and a defect for inspecting a defect of the edge portion 1a of the wafer 1 ′ based on the irradiation position of the inspection light and the intensity of the scattered light. Inspection means 8 '. In the defect inspection apparatus 0 ″, a plurality of wafers 1 ′ are supported by a support shaft 2 while being stored in a wafer cassette 18. A rotating means 3 such as a motor for controlling the rotation angle is connected to the support shaft 2, and rotates a plurality of wafers 1 'at a predetermined speed in the wafer cassette 18. A rail 20 is provided above the wafer cassette 18 along the longitudinal direction of the wafer cassette 18, and a sensor unit 19 having an illumination LED array 5 ′ and a line CCD sensor 7 ″ is provided. It runs on the rail 20. The inspection light 4 emitted by the illumination LED array 5 'is scattered by the edge 1a of the wafer 1', is converged by the cylindrical lens 21, and then forms an image on the line CCD sensor 7 ''. The output of the line CCD sensor 7 ″ is quantized via an A / D converter 22, and is stored as digital information in a defect inspection unit 8 ′ realized by a computer.

When a defect inspection is performed in the defect inspection apparatus 0 ″, the operation is performed according to a flowchart shown in FIG. First, a motor (not shown) of the sensor unit 19 is driven while the rotating unit 3 is stationary,
The longitudinal end of the wafer cassette 18, for example, a in FIG.
The sensor unit 19 is arranged at the point (S101). Then, the illumination LED array 5 ′ provided in the sensor unit 19.
Irradiates the inspection light 4 to the edge 1a of the wafer 1 '
The scattered light 6 is received by the line CCD sensor 7 ″. The line CCD sensor 7 ″ is provided in the sensor section 19 with its longitudinal direction along the wafer 1 ′, and a predetermined range of the edge section 1a is imaged at a time. The image signal photoelectrically converted by the line CCD sensor 7 '' is quantized via the A / D converter 22, and is stored in the defect inspection means 8 'as digital information (S102).
Next, the sensor unit 19 is moved by a predetermined amount toward the other end in the longitudinal direction of the wafer cassette 18 according to the required resolution, and after being brought into a stationary state, the edge unit 1 of the wafer 1 'is
The imaging of a is performed (S103). The sensor unit 19 is located at the position of point b at the other end of the wafer cassette 18 in the longitudinal direction.
The movement of the sensor unit 19 and the image pickup are repeated until (S104) is reached (S104), and a part of the edge 1a is imaged for all the wafers 1 'stored in the wafer cassette 18, and the defect inspection means 8 'holds the image signal. When the sensor unit 19 reaches the point b, the sensor unit 19
Is moved to point a (S105). The image signal held in the defect inspection means 8 'is configured as a two-dimensional signal as shown in FIG. 11 (S106). In FIG. 11, the horizontal direction is the moving direction of the sensor unit 19, and the vertical direction is the longitudinal direction of the line CCD sensor 7 ''. Next, a defect inspection is performed on the two-dimensional image formed by the processes S101 to S106 (S10).
7). In the defect inspection for the two-dimensional image, first,
An image is cut out for each wafer from the two-dimensional image (S1071). This cutting can be performed, for example, based on the mounting position of the wafer 1 '. FIG.
(A), (b), and (c) show examples of cut out images. For example, FIG. 12A is an image of the edge portion of the second wafer 1 ′ (# 2) counted from the point a.
(B) is the third wafer 1 '(#
FIG. 12C is an image of an edge portion of the wafer 1 ′ (# 4), which is the fourth wafer counted from the point a. Next, a defect inspection is performed using the plurality of clipped image signals. For example, when performing a defect inspection on the # 1 wafer 1 ′ showing the cutout image in FIG. 12 (b), assuming that the # 2 wafer 1 ′ showing the cutout image in FIG. 12 (a) is used as the reference image, The registration of the two images is performed. This alignment is performed by, for example, detecting a position shift of an image by a normal correlation operation and shifting one image by the position shift. When the positioning is performed, the absolute value of the difference between the two images is obtained, and an absolute value difference image is generated (S1072).
Note that the difference between two images means the calculation of the difference between pixels at the same position in the image.

At this time, if there are no abnormal luminance portions in the two images, basically all the pixels of the images are almost zero. on the other hand,
If the cutout image has an abnormal luminance portion, a bright image area is generated in the absolute value difference image. For this reason, the absolute value difference image is binarized with an appropriate threshold value, and a binarized image as shown in FIG. 12D is generated (S1).
073). Next, it is determined whether or not a pixel exceeding the threshold exists in the binary image (S107).
4). When it is determined that there is no image exceeding the threshold value, it is determined that no defect exists and no abnormality exists in the imaged portion of the edge portion of the wafer # 1 of the above # 3. (S1075). On the other hand, if it is determined that there is a pixel exceeding the threshold value in the absolute difference image, that portion, that is, a bright portion in FIG. 12D is determined to be a defective portion. It is unknown which of the two images used to generate the absolute difference image has a defect. Therefore, the above-described processing is repeated using the cut-out images of different wafers 1 ′ as the reference images. For example, a cut-out image of wafer # 4 of # 4 shown in FIG. 12C is used as the reference image. Also in this case, first, the wafer 1 ′ of # 3
Is aligned with the cut-out image of wafer # 1 of # 4, and an absolute value difference image is obtained (S1076). Next, the absolute value difference image obtained in the above processing S1076 is binarized by a predetermined threshold value,
For example, a binarized image as shown in FIG. 12E is obtained (S1077). Next, it is determined whether there is a pixel exceeding the threshold value in the binarized image (S1078). If not, an image of the edge portion of the # 1 wafer 1 'is taken. For the portion, it is determined that there is no defect (S1075), and if there is, it is determined that there is an abnormality in the imaged portion of the edge of wafer # 3 (S1079). The above processes S1071 to S1079 are repeated for all the wafers 1 'stored in the wafer cassette 18, and when the processing is completed, information on the defect including the number of the defective wafer, for example, # 3, is transmitted to the defect inspection means 8'. The digital data held in the defect inspection means 8 'is discarded (S108). This enables the line CCD
Since the defect inspection has been performed on all the wafers 1 ′ stored in the wafer cassette 18 within the range that can be imaged at one time using the sensor 7 ″, the defect inspection on the edge portion of the wafer 1 ′ has not been performed. In order to image the portion, the support shaft 2 is driven by the rotating means 3, and the wafer 1 'stored in the wafer cassette 18 is rotated by a predetermined amount in the circumferential direction (S109). Next, it is determined whether or not the wafer 1 'has made one rotation, that is, whether or not inspection in the entire circumferential direction of the wafer 1' has been completed (S110).
If it is determined that the wafer 1 'has not made one rotation, the above-described processes S102 to S109 are repeated, and if it is determined that the wafer 1' has made one rotation, a defect such as a defective wafer number Is displayed on a display device connected to a computer that implements the defect inspection means (S111).
As described above, in the defect inspection apparatus 0 ″, the edges of a plurality of wafers are inspected simultaneously, so that the time required for the inspection can be reduced. In addition, by comparing captured images of a plurality of wafers, a defective portion can be emphasized and discrimination can be facilitated. In the defect inspection apparatus 0 ″, a line CCD is used as an imaging unit for the wafer 1 ′.
Although the sensor 7 '' has been used, the present invention is not limited to this. For example, a two-dimensional CCD sensor may be used. In this case, since the image can be cut out in units of the two-dimensional CCD, it is not always necessary to cut out the image.

In the defect inspection apparatus 0 ″, the defect inspection is performed on all the wafers 1 ′ stored in the wafer cassette 18 by moving the sensor unit 19 on the rails 20. For example, the sensor unit 19 may be fixed and the wafer cassette 18 may be fixed.
And the wafer 1 'therein may be moved.
In the defect inspection apparatus 0 ″, a plurality of wafers 1 ′ are collectively rotated by the support shaft 2 in the circumferential direction. However, a plurality of driving units are synchronized to rotate each wafer 1 ′. You may make it do. In the defect inspection apparatus 0 ″, defects are inspected at all points in the circumferential direction of the wafer 1 ′. However, a notch or an orientation flat (so-called orientation flat) for indicating the direction of the wafer 1 ′ is used. ) May be provided to omit the defect detection of the notch portion or the orientation flat portion.
Such a defect inspection device is also an example of the defect inspection device in the present invention.

In the defect inspection apparatus 0 ', a plurality of optical fibers are used to simultaneously image the edges of the plurality of inspected members 1. For example, a line CCD is used.
It is also possible to directly inspect the edge portion for defects using a sensor. However, if the wafer is supported coaxially,
As shown in FIG. 5 (a), the edge of the wafer is provided with an inclined chamfered portion, so that the distance from the line CCD sensor differs slightly depending on the location of the chamfered portion, causing blurring. Therefore, the positional relationship between the line sensor and each wafer is set such that the chamfered portions of all the wafers include the predetermined line, so that the chamfered portions of all the wafers coincide with the focal positions of the line sensors. FIG. 13A shows the overall configuration of such a defect inspection apparatus.
FIG. 13B shows a configuration example of a turntable provided in the defect inspection apparatus. As shown in FIGS. 13A and 13B, the defect inspection apparatus 130 has an edge portion (outer peripheral edge portion).
Rotary table (an example of mounting means) 132 for mounting a plurality of wafers 131 each having a chamfered portion (inclined surface) 132
And each wafer 13 placed on the rotary table 132
A positioning mechanism (corresponding to positioning means) 133 for positioning the rotary table 132 so that the corresponding inclined surface includes a predetermined line, and the rotary table 132 positioned by the positioning mechanism 133 are driven to drive the wafer 1.
Rotating means 134 for rotating 31 in the horizontal plane, and a line CCD sensor (imaging means) 135 for taking an image of the inclined surface of each wafer rotated by the rotating means.
And an image processing device (corresponding to a defect inspection unit) 136 that performs image processing on the image of the inclined surface of each wafer captured by the line CCD sensor 135 to inspect for defects.

The defect inspection apparatus 130 is an apparatus capable of simultaneously inspecting the edge portions of ten wafers 131, for example. The ten wafers 131 to be inspected are transferred from the wafer cassette to respective predetermined positions on the rotary table 132 by a transfer mechanism (not shown). The position of each rotary table 132 can be adjusted by a positioning mechanism 133 driven by a stepping motor 1331 or the like. The inclination angle of the chamfered portion of the wafer 131 to be inspected beforehand is input to the positioning mechanism 133, and based on the current position of each rotary table 132 detected by the position detector 1332 such as an encoder, FIG.
As shown in FIG. 4, the control of the stepping motor 1331 and the like is performed so that the chamfered portion 131A of each wafer 131 includes the predetermined line L1. Each rotating table 132 has rotating means 134 including a belt 1341, a driving motor 1342, etc., for rotating the wafer 131 in the horizontal plane.
Is connected. Rotating means 134 connected to each rotary table 132 are synchronized with each other, rotate each rotary table 132 at a predetermined speed, and rotate a wafer 131 placed on each rotary table 132 in its horizontal plane. . The chamfered portion 131A of the edge portion of the wafer 131 placed on the rotary table 132 has a line C
The image is captured by the CD sensor 135. This line CCD
The focal position of the sensor 135 is set on the predetermined line L1, and it is possible to collectively image the chamfered portions 131A of the edges of the plurality of wafers 131. Further, since the chamfered portions 131A of the edge portions are provided on the front side and the back side of the wafer 131, the line CCD sensors 135 are also provided on the front side and the back side, respectively, so that they can be inspected simultaneously. The one-dimensional image signal captured by the line CCD sensor 135 is supplied to an image processing device 136. This image signal is scanned in the circumferential direction of the wafer 131 by the rotation of each rotary table 132 by the rotating means 134, and is applied to the front side or the back side of the wafer 131, for example, as shown in FIG.
A two-dimensional image as shown in FIG. 5 is constructed. The vertical direction of the image shown in FIG. 15 indicates the circumferential direction of the wafer, and the horizontal direction indicates the predetermined line direction. These image signals are displayed on a display, and a person in charge of inspection can perform a visual inspection for defects by monitoring the display. Since the chamfered portion imaged by the line CCD sensor 135 is illuminated by an illuminator (not shown), the chamfered portion 131A basically becomes a bright portion and the other portions become darker portions. Here, FIG. 16 shows an example of imaging a defect. As shown in FIG. 16, for example, a concave defect such as a chip is detected darker than a normal chamfered portion, and a convex defect such as a protrusion is detected brighter than a normal chamfered portion. The above image captured by the line CCD sensor 135 is subjected to predetermined image processing by an image processing device 136, and a defect inspection is performed. For example, if the line width of the chamfered portion 131A becomes narrower than the threshold value, or if the area of a dark portion (dark spot) or a bright portion (bright spot) exceeds a predetermined value, the portion is detected as a defect. These threshold values are set in advance using, for example, a captured image of a test wafer before inspecting a defect. As described above, in the defect inspection apparatus according to the present embodiment, since the positional relationship between the plurality of wafers and the line CCD sensor is set so that the chamfered portion of each wafer includes a predetermined line, the defect inspection of the chamfered portion is performed. The inspection can be performed collectively using the line sensor, and the time required for the inspection can be reduced.

In the defect inspection apparatus 130, a line CCD is used to image the chamfered portion 131A of the edge.
Although the sensor 135 is used, the present invention is not limited to this, and other imaging means such as an area sensor can be used. For example, when an area sensor is used, the chamfered portion 131A near the predetermined line L1 is imaged by the area sensor. Such a defect inspection device is also an example of the defect inspection device in the present invention. In addition, the defect inspection apparatus 1
In 30, the inspection processing is performed after constructing a two-dimensional image in the image processing device 136. However, the present invention is not limited to this. For example, the defect inspection may be performed in a one-dimensional signal state as shown in FIG. It may be. For example, since the chipped portion is smaller than the normal luminance level of the chamfered portion, the defect can be inspected by setting an appropriate threshold value. Such a defect inspection device is also an example of the defect inspection device in the present invention. Further, in the defect inspection apparatus 130, the line CCD sensors 135 are provided on the front side and the back side of the wafer 131 in order to simultaneously inspect both sides of the wafer 131, but the present invention is not limited to this.
An imaging unit such as a line CCD sensor may be provided only on the front side or the back side. Such a defect inspection device is also an example of the defect inspection device in the present invention. Further, the defect inspection apparatus 130 performs the defect inspection based on the width of the chamfered portion and the area of the dark spot or the bright spot. However, the present invention is not limited to this. Brightness distribution,
The defect inspection may be performed based on the detection position or the like. Such a defect inspection device is also an example of the defect inspection device in the present invention. Further, similarly to the defect inspection apparatus 0 ″, the defect inspection apparatus 130 can also perform defect inspection by comparing a captured image of one wafer with a captured image of another wafer. Such a defect inspection device is also an example of the defect inspection device in the present invention.

[0020]

As described above, the defect inspection apparatus according to the present invention collectively irradiates the inspection light to the edge portions of a plurality of inspected members which are simultaneously rotated. Inspection of defects such as cracks and chips can be performed quickly, and a decrease in yield due to defects at the edge can be suppressed. In the case where a plurality of scattered light detecting means are provided, for example, by providing a light shielding plate between the scattered light detecting means, it is possible to eliminate the influence of the scattered light from the adjacent inspected member. Further, when a scattered light detecting means that captures a two-dimensional image of the surface of the edge in the rotation direction and the thickness direction of the inspected member is used, a defect is detected at any position of the edge of the inspected member. Inspection can be performed in more detail, and the shape of the defect can be used as a reference for the defect inspection, so that the accuracy of the defect inspection can be improved. Further, by providing optical fibers for guiding the scattered light scattered at the edge of the inspected member to the scattered light detecting means on each of the front side and the back side of the edge of the inspected member, the edge of the inspected member can be further improved. Inspection can be performed in detail. Further, when the defect inspection means is to inspect the defect of the inspected member based on a synthesized image obtained by synthesizing the images of the edge portion surfaces of the plurality of inspected members captured by the scattered light detecting means,
It is possible to perform an accurate and comprehensive inspection based on the correlation between the defects of each inspected member. In the case where the defect inspection means is for inspecting a defect of a wafer by comparing captured images of the surface of an edge portion of a plurality of wafers captured by the scattered light detection means with each other, for example, selecting one of the captured images. The two captured images thus aligned are aligned, a difference image composed of the absolute value of the difference of each pixel of the two aligned captured images is generated, and the difference image is determined using a predetermined threshold value. By performing the evaluation, an accurate inspection based on the correlation of each wafer can be performed. According to the defect inspection apparatus of another invention, the mounting means is positioned by the positioning means such that the corresponding inclined surface of each wafer includes a predetermined line. However, the imaging means can collectively image the inclined surfaces of a plurality of wafers, and the inspection can be performed quickly. Further, in the above-described defect inspection apparatus, since the imaging means is provided for each of the front surface and the back surface of the wafer, the front surface and the back surface of the wafer can be simultaneously inspected. it can. In the defect inspection apparatus, the defect inspection unit may perform, for example, alignment of two images selected from images of each wafer based on the images of the plurality of wafers captured by the imaging unit, If a difference image consisting of the difference between the pixels of the two aligned images is generated, and the difference image is evaluated using a predetermined threshold value, the inspection is performed if the defect of the wafer is inspected. The inspection can be performed quickly, and an accurate inspection can be performed based on the correlation between the wafers.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a defect inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing an example of an inspection result of the defect inspection apparatus.

FIG. 3 is a diagram showing a simplified configuration of a defect inspection apparatus according to one embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a defect inspection apparatus according to another embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of an inspection image captured by a defect inspection apparatus according to another embodiment.

FIG. 6 is a diagram showing a modification of the defect inspection apparatus according to the other embodiment.

FIG. 7 is a diagram showing another modification of the defect inspection apparatus according to the other embodiment.

FIG. 8 is a diagram showing a schematic configuration of a defect inspection apparatus 0 ″ according to still another embodiment of the present invention.

FIG. 9 is a diagram for explaining in detail a sensor unit included in the defect inspection apparatus 0 ″.

FIG. 10 is a flowchart for explaining the operation of the defect inspection apparatus 0 ″.

FIG. 11 is a view for explaining an image captured by the defect inspection apparatus 0 ″.

FIG. 12 is a view for explaining image processing for defect inspection in the defect inspection apparatus 0 ″.

FIG. 13 is a diagram showing a schematic configuration of a defect inspection apparatus 130 according to still another embodiment of the present invention.

FIG. 14 is a view for explaining the operation of a positioning mechanism provided in the defect inspection apparatus 130.

FIG. 15 is a view for explaining an image captured by the defect inspection apparatus 130.

FIG. 16 is a view for explaining an example of defect detection in the defect inspection apparatus 130.

FIG. 17 is a view for explaining a modification of the defect inspection apparatus 130.

FIG. 18 is a diagram showing a basic configuration of a conventional semiconductor wafer defect inspection apparatus.

FIG. 19 is a diagram showing another example of a conventional defect inspection apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inspection member 1 ', 131 ... Wafer 2 ... Support shaft 3.134 ... Rotating means 4 ... Inspection light 5 ... Inspection light irradiation means 6 ... Scattered light 7 ... Scattered light detection means 8, 8' ... Defect inspection means 11 ... Light shielding plate 132... Rotating table 133... Positioning mechanism 135.

Continuing from the front page (72) Inventor Shingo Sumie 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel, Ltd. Kobe Main Office (72) Inventor Hideo Katsumi 1-5-1, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture 5 Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Tsutomu Morimoto 1-5-5 Takatsukadai, Nishi-ku, Kobe, Hyogo Prefecture Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Akishi Imanishi Hyogo 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Kobe Steel Engineering Co., Ltd. (72) Inventor Hidehisa Hashizume 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel No. 5 Building Genesis Technology Inside (72) Inventor Yuji Yamamoto 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel No. 5 Building Genesis Technology Co., Ltd.

Claims (19)

[Claims] 1. A support shaft capable of supporting a plurality of disk-shaped inspected members coaxially, rotating means for driving the support shaft to rotate the inspected member, and rotating by the rotating means. Inspection light irradiating means for irradiating inspection light to an edge portion of the inspected member; scattered light detecting means for detecting scattered light irradiated and scattered on the edge portion of the inspected member by the inspection light irradiating means; A defect inspection apparatus comprising: defect inspection means for inspecting a defect at an edge portion of the inspection target member based on an irradiation position of inspection light and an intensity of the scattered light. 2. The defect inspection apparatus according to claim 1, wherein the inspection light irradiating means irradiates the slit light along the support shaft over a plurality of inspected members. 3. The defect inspection apparatus according to claim 2, wherein the scattered light detection means is provided for each of the inspected members supported by the support shaft. 4. The defect inspection apparatus according to claim 3, wherein a light shielding plate is provided between each scattered light detecting means. 5. The defect inspection apparatus according to claim 1, wherein said inspection light irradiating means sequentially scans a plurality of inspected members with spot light. 6. The defect inspection apparatus according to claim 1, wherein the inspected member is a semiconductor wafer. 7. The apparatus according to claim 1, wherein the scattered light detecting means captures a two-dimensional image of the surface of the edge portion in the rotation direction and the thickness direction of the member to be inspected. Described defect inspection apparatus. 8. The CCD according to claim 1, wherein said scattered light detecting means has an imaging range at least as thick as an edge of said member to be inspected.
The defect inspection device according to claim 7, which is a camera. 9. The defect inspection apparatus according to claim 7, wherein said scattered light detection means is provided so as to be movable in a thickness direction of an edge portion of said member to be inspected. 10. The defect inspection apparatus according to claim 7, wherein the scattered light scattered at the edge of the inspected member is guided to the scattered light detection means by an optical fiber. 11. The defect inspection apparatus according to claim 10, wherein a light incident portion of said optical fiber is provided on each of a front surface side and a rear surface side of an edge portion of said inspected member. 12. The defect according to claim 7, wherein the scattered light scattered at the edge of the inspected member is guided to the scattered light detecting means using a lens and a mirror. Inspection equipment. 13. The defect inspecting means inspects a defect of the inspected member on the basis of a composite image obtained by compositing images of the surface of the edge of the plurality of inspected members imaged by the scattered light detecting means. Any one of claims 7 to 12
The defect inspection device according to the paragraph. 14. The defect inspection means according to claim 7, wherein said defect inspection means inspects the defects of each wafer by comparing the images taken by the scattered light detection means on the surface of the edge portion of a plurality of wafers. The defect inspection apparatus according to any one of claims 12 to 12. 15. The defect inspection means performs positioning on two selected images among the captured images, and generates a difference image including a pixel-by-pixel difference between the two aligned images. 15. The defect inspection apparatus according to claim 14, wherein each of the wafers is inspected for a defect by evaluating the difference image using a predetermined threshold value. 16. A mounting means for mounting a plurality of wafers each having an inclined surface at an outer peripheral end, and an upper surface such that a corresponding inclined surface of each wafer mounted on the mounting means includes a predetermined line. Positioning means for positioning the mounting means; rotating means for driving the mounting means positioned by the positioning means to rotate the wafer; and capturing an image of the inclined surface of each wafer rotated by the rotating means. A defect inspection apparatus comprising: an imaging unit; and a defect inspection unit that inspects a defect by performing image processing on an image of an inclined surface of each wafer captured by the imaging unit. 17. The defect inspection apparatus according to claim 16, wherein said imaging means is provided for each of a front surface and a back surface of the wafer. 18. The defect inspection apparatus according to claim 14, wherein the defect inspection unit inspects a defect of the wafer based on images of the plurality of wafers imaged by the imaging unit. 19. The defect inspection means performs registration with respect to two selected images among images of each wafer, and calculates a difference comprising an absolute value of a difference between pixels of the two aligned images. 19. The defect inspection apparatus according to claim 18, wherein each of the wafers is inspected for defects by generating an image and evaluating the difference image using a predetermined threshold value.