JP2000114329A - Method and device for inspecting ground edge section of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device by which only defectless semiconductor substrates are fed to a succeeding semiconductor process by mechanically prechecking the outer peripheral surfaces of the substrates and the ground edge faces of the surfaces for microdefects, such as chipping, etc., before the substrates enter the semiconductor process. SOLUTION: The image of the surface to be inspected of a substrate 1, having an outer peripheral edge chamfered by grinding is picked up by an image-pickup device 4 which picks up the image of either the chamfered edge faces of the substrate 1 or the outer peripheral side faces of the substrate 1 between the chamfered edges, by moving at least either one of the substrate 1 and device 4 so that relative movement may be caused between the substrate 1 and device 4 and the normal/defective surface of the substrate 1 is discriminated, by comparing the inspection image 21 with a reference image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting the appearance of an outer peripheral edge of a semiconductor substrate.

[0002]

2. Description of the Related Art In recent years, the semiconductor industry has been pushing the trend toward higher integration of semiconductors and further cost reduction to the ultimate speed. As a result, the diameter of one semiconductor substrate has been increased, and semiconductor manufacturing using a large-diameter substrate such as 8 inches is now becoming common.

On the other hand, a number of steps are required until a semiconductor substrate becomes a semiconductor chip, during which time the semiconductor substrate is transported to another processing apparatus every time the processing apparatus changes. This transfer may be carried out automatically by a machine in a state of being stored one by one or in a dedicated transfer container, or may be carried out manually.

As described above, the larger the diameter of a semiconductor substrate and the higher the degree of integration, the more the cost per unit increases geometrically. Poor quality has led to significant losses. One cause of such a defect of the semiconductor substrate is chipping of an edge during transportation. In other words, a semiconductor is made by cutting a single crystal bar into thin pieces and polishing the outer peripheral surface and surface of the rod.
(Generally called a semiconductor wafer) is formed on the surface, the surface is polished only, the edge is standing, the edge is chipped by light contact during transportation,
This becomes a starting point and grows into hair cracks during the semiconductor process, and in severe cases, causes cracks and other defects. Therefore, at present, the outer peripheral side surface and the edge of the semiconductor substrate are ground and chamfered to eliminate the occurrence of the defect.

[0005] In spite of the fact that the chamfering is performed by edge grinding in this way, a new problem arises in the chamfered portion. That is, when the sharpness of the chamfering grindstone is clogged or the sharpness is reduced, fine chipping occurs on the ground surface, and this causes contamination (contamination) generated during the complicated and diverse semiconductor manufacturing process. Was found to be the cause.

Therefore, at present, after the outer peripheral surface and the edge are chamfered and ground, an operator visually inspects the ground surface to check whether or not the ground surface has a defect.
Except for this, only good products are sorted out. However, if the defect is minute, for example, about 50 to 100 μm, it is difficult to find the defect by visual inspection, and there is a limit.

[0007]

The technical solution of the present invention is to mechanically check the presence or absence of micro defects such as chipping on the outer peripheral surface of a semiconductor substrate and its ground surface before entering a semiconductor process. It is another object of the present invention to provide only a semiconductor substrate having no defect to a subsequent semiconductor process.

[0008]

According to a first aspect of the present invention, there is provided a method of inspecting a ground surface of a substrate edge portion, wherein the substrate to be inspected has an outer peripheral edge chamfered by edge grinding and a surface to be inspected. The outer peripheral side surface between the chamfered surface (2) and the chamfered surface (2) of the substrate to be inspected (1)
(3) so that relative movement occurs with the imaging device (4) for imaging at least one of the inspection target surface (2) of the inspection target substrate (1) by moving at least one of them. 3) is imaged, and the inspection image (21) is compared with the reference image (20) to judge the appearance of the surfaces to be inspected (2) and (3). "

According to this method, since the inspected surfaces (2) and (3) of the inspected substrate (1) having been subjected to the edge grinding are mechanically inspected in advance, the defective product is removed before entering the semiconductor process. It can be removed and contamination caused by end grinding can be prevented.

A second aspect of the present invention relates to an example of a grinding surface inspection apparatus for carrying out the method of the present invention, wherein "an operation for rotating a disk-shaped substrate to be inspected (1) whose outer peripheral edge is chamfered by edge grinding. Device (5) and an imaging device (4) for imaging at least one of the outer peripheral side surface (3) between the chamfered surface (2) and the chamfered surface (2) of the substrate to be inspected (1) to be inspected. ), Comparing the inspection image (21) of the inspected substrate (1) outputted from the imaging device (4) with the reference image (20) of the non-defective product, and the quality of the appearance of the inspected surfaces (2) and (3). And a judging device (6) for judging. "

The grinding surface inspection apparatus according to claim 3 can inspect not only a case where the substrate to be inspected (1) is a disk but also a case where the substrate to be inspected is a rectangle or any other irregular shape in the general example including the second aspect. `` The chamfered surface (2) and the chamfered surface (2) to be inspected of the substrate (1) whose outer peripheral edge is chamfered by edge grinding
An imaging device (4) for imaging at least one of the outer peripheral side surfaces (3) between the inspection surface (2) and (3) so that the inspection surface (2) (3) passes through an imaging region (7) of the imaging device (4). An operation device (5) for moving the substrate to be inspected (1), and an inspection image (21) of the substrate to be inspected (1) output from the imaging device (4) and a reference image (20) of a good product are compared. Judgment device (6) to judge the appearance of the substrate to be inspected (1)
And "is composed of

A grinding surface inspection apparatus according to a fourth aspect is an image pickup device (4) that moves in the reverse case of the third aspect, wherein the substrate to be inspected is
Not only when (1) is a disk, but also the statically inspected substrate (1)
The image of the inspected surfaces (2) and (3) of `` the inspected substrate (1) whose outer peripheral edge has been chamfered by edge grinding, the chamfered surface (2) and the chamfered surface (2 An imaging device (4) for imaging at least one of the inspected surfaces (2) and (3) of the outer peripheral side surface (3) between the imaging surface (2) and the imaging device (3) along the inspected surfaces (2) and (3). Four)
Actuating device (5) for moving the inspection image (21) of the substrate to be inspected (1) output from the imaging device (4) and a non-defective reference image
(20) and a determination device (6) for determining the appearance of the substrate to be inspected (1). "

Thus, the quality of the appearance of the ground surface of the substrate to be inspected (1) is determined, and only non-defective products having no defect (16) are selected and supplied to the next semiconductor process.

According to a fifth aspect of the present invention, there is provided the grinding surface inspection apparatus according to the second to fourth aspects, wherein "the defect (16) of the inspected surfaces (2) and (3) is illuminated by illuminating the imaging region (7) of the imaging device (4). A lighting device (8) for illuminating the lighting device is provided. "

By appropriately selecting the illumination direction, color, and the like of the illumination device (8), the defect (16) on the surface to be inspected (2) (3) can be raised as a bright point, and the minute defect ( 16) facilitate discovery.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. The substrate to be inspected (1) is, for example, a disk-shaped 6 to 8 inch (of course, may be larger or smaller) large-diameter semiconductor wafer (disk), solar cell power generation substrate (rectangle), liquid crystal Although there is a glass substrate (rectangular), a large diameter semiconductor wafer will be described here as an example.

The substrate to be inspected (1) is disk-shaped and has an outer peripheral side surface.
(3) and the outer peripheral edge portion are chamfered by grinding. Outer side surface between this chamfered surface (2) and chamfered surface (2)
In (3), when the sharpness of the grindstone (not shown) deteriorates, chipping, which is a fine pit-like defect, and fine cracks occur on the ground surfaces (2), (3). Therefore, in the present invention, the ground surfaces (2) and (3) are inspection surfaces.

FIGS. 1 to 3 show an example of an inspection apparatus according to the present invention. The inspection apparatus is provided with a housing body (10) and a disk-shaped inspection substrate (1) provided on the housing body (10). An operating device (5) for rotating, a positioning device (15) for positioning the substrate to be inspected (1) held on a spin chuck (5a) described later of the operating device (5), and a substrate (1) to be inspected. The robot hand (11) to be moved and the storage container (19) containing the untested and inspected substrates to be inspected (1)
A substrate holding stage (12) holding a defective product container (not shown), and a defective product stage (13) for holding a defective product storage container (not shown), and a column (14) erected on the housing body (10). A pair of upper and lower imaging devices (4) attached, an illumination device (8) disposed close to the imaging device (4), and a substrate to be inspected (1) output from the imaging device (4). A judging device (6) for comparing the inspection image (21) and the non-defective reference image (20) to judge the appearance of the inspected surfaces (2) and (3).
And a monitor CRT (9) for displaying the images (20) and (21).

The operating device (5) comprises a spin chuck (5a) for sucking and holding the substrate to be inspected (1) and a driving device (5b) for rotating the spin chuck (5a). Concentric and radial grooves (5c) communicating with each other on the suction surface of the spin chuck (5a)
Are formed and connected to a reduced pressure source (not shown). Further, since the drive device (5b) needs to accurately rotate the substrate to be inspected (1) once at a set speed, for example, a stepping motor with a rotary encoder or the like is used.

The positioning device (15) includes a spin chuck (5a)
The robot comprises a pair of positioning arms (15b) provided with two pins (15a) erected on both sides of the robot and an arm operating section (15c) for expanding and contracting the positioning arms (15b). A positioning operation for aligning the center of the uninspected substrate to be inspected (1) transferred onto the spin chuck (5a) by the hand (11) with the center of the spin chuck (5a) is performed.

The robot hand (11) is disposed adjacent to the actuator (5), and the substrate (1) to be inspected is moved by the articulated arm (11a) to the substrate holding stage (12) or the stage for defective products. (13) Alternatively, it can be freely transferred to the spin chuck (5a). The distal end of the articulated arm (11a) is a vacuum suction surface (11b), which functions to suck the back end of the substrate to be inspected (1) and transfer it to a required department.

The image pickup device (4) is a device such as a CCD camera or a line sensor camera that can capture an inspection image (21) of the inspection surfaces (2) and (3) of the inspection substrate (1). In the present embodiment, since the main surface to be inspected is the chamfered surface (2), two imaging devices (4) arranged obliquely downward and obliquely upward from above and below with respect to the substrate to be inspected (1) are housings. It is attached to a column (14) erected on the main body (10). This makes the chamfer surface
(2) is imaged from the front, and the outer peripheral side surface (3) is imaged obliquely.

The illuminating device (8) is, for example, a fluorescent lamp, and is disposed close to the imaging device (4).
4) is attached. Of course, the lighting device (8) is not limited to a fluorescent lamp, and a halogen lamp, a xenon lamp, or another appropriate light source is used.

The judging device (6) is a part which can be said to be the heart of the present device, and the inspection image (21) output from the imaging device (4)
And a non-defective reference image (20) to determine the quality of the appearance of the inspected surfaces (2) and (3). Therefore, the surface to be inspected (2) (3)
If there is a defect (16) in the inspection image (21) and it is reflected in the inspection image (21), the defect (16) is detected by comparing with the reference image (20) in which the defect (16) is not reflected, and the defective product is detected. After the inspection, the robot hand (11) transfers the defective product to the defective container. Conversely, if the inspection image (21) matches the reference image (20), it is determined to be non-defective, and after the inspection is completed, the robot hand (11)
Is returned to the non-defective storage container (19).

The monitor CRT (9) has a reference image (20) and an inspection image.
(21) is always displayed, and the worker
The inspection status can be confirmed by visually observing the image projected on T (9).

Next, the operation of the present invention will be described. First, a non-defective substrate to be inspected (1) is imaged and a reference image (20) is taken in, and a non-defective substrate to be inspected (1) inspected in advance is used directly or by using a robot hand (11). And put on the spin chuck (5a).

Subsequently, the positioning device (15) is operated to move the positioning arm (15b) in the closing direction.
In (15a), the center of the substrate to be inspected (1) is aligned with the rotation center of the spin chuck (5a) by sandwiching the outer peripheral side surface (3) of the substrate to be inspected (1). When the centers match, the spin chuck (5a) is connected to a decompression source to spin the substrate (1) to be inspected (5a).
Adsorb to.

In this state, when the spin chuck (5a) is rotated once at a predetermined speed, a pair of upper and lower imaging devices (4) arranged toward the chamfered surface (2) of the substrate (1) to be inspected are illuminated. apparatus
Under appropriate illumination according to (8), the upper chamfer (2) without defects (16) and the outer side (3) without defects (16) and the lower chamfer (2) without defects (16) The outer peripheral side surface (3) having no defect (16) is imaged, and recorded as a series of reference images (20) on the sub-scanning time axis. When the loading of the reference image (20) is completed,
Release the chuck of the spin chuck (5a) and check the good substrate
(1) is removed, and the inspection proceeds to the untested substrate (1) to be inspected.

First, the storage container (19) storing the untested substrate (1) to be inspected is set on the substrate holding stage (12). The storage container (19) has a known shape, and has a structure in which the test substrates (1) can be inserted and removed one by one and held. In this state, the robot hand (11) is operated to
One sheet of (1) is extracted and placed on the spin chuck (5a).

Thereafter, after the positioning is performed in the same manner as described above, the spin chuck (5a) is rotated once at a predetermined speed, and the surface to be inspected (2) is rotated.
(3) is imaged, and an inspection image (21) is obtained in the same procedure as described above.
If there are no defects (16) on the surfaces (2) and (3) to be inspected, they completely match the reference image (20), and the judging device (6) judges the inspected substrate (1) as a non-defective product. The substrate to be inspected (1) determined to be non-defective is returned to the storage container (19) by the robot hand (11) after the suction of the spin chuck (11) is released.

Conversely, if there are any defects (16) on the surfaces (2) and (3) to be inspected, the defects (16) appear on the inspection image (21) as bright spots and appear on the reference image (20). It does not match. In that case, the determination device (6) determines that the product is defective, and after the suction of the spin chuck (11) is released, the device is sent to the defective product container by the robot hand (11). In this way, the substrate to be inspected
(1) 100% check is performed promptly to prevent the occurrence of contamination due to the defect (16) generated on the ground surfaces (2) and (3).

In the above embodiment, the substrate to be inspected (1) is disk-shaped, and the substrate to be inspected (1) is rotated and the imaging device (4) is stationary.
As a representative example, the inspection of the grinding surfaces (2) and (3) at the ends is shown as a representative example.However, when the substrate to be inspected (1) is rectangular, the grinding operation of the grinding surfaces (2) and (3) is Inspection cannot be performed. In such a case, the imaging area (7) of the imaging device (4) is
Move the spin chuck (5a) so that (3) passes,
A continuous inspection image (21) is obtained. (See FIG. 6B) Conversely, the imaging device (4) moves along the inspected surfaces (2) and (3) at the end of the stationary inspected substrate (1) having a circular or irregular shape, and the inspected surface is moved. (2) (3) may be imaged. (See Fig. 6 c)
Also, depending on the type of defect (16) on the inspected surfaces (2) and (3), mere illumination may not be sufficient.In such a case, the optimal illumination direction, color, etc. for the defect (16) are considered. By appropriately selecting, it is possible to make the defect (16) stand out as a bright spot and to easily find the minute defect (16). Of course, lighting is not always necessary, and defects without lighting (16)
If can be detected sufficiently, the illumination can be deleted.

[0033]

As described above, according to the present invention, the inspected surface of the inspected substrate which has been subjected to edge grinding in advance is mechanically inspected, so that defective products can be removed before entering the semiconductor process. As a result, it is possible to prevent contamination caused by end grinding. In addition, by appropriately selecting the illumination direction, color, and the like of the illumination device in the imaging step, the defect on the surface to be inspected can be raised as a bright spot, and a minute defect can be easily found.

[Brief description of the drawings]

FIG. 1 is a front view of the apparatus of the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a side view of FIG. 1;

FIG. 4 is a perspective view and a partially enlarged perspective view of two types of semiconductor substrates to which the present invention is applied.

FIG. 5 is a drawing for comparing a reference image and an inspection image captured by the apparatus of the present invention.

FIG. 6 is a schematic view of another embodiment of the present invention.

Claims (5)

[Claims] 1. An imaging method for imaging at least one of a substrate to be inspected whose outer peripheral edge is chamfered by edge grinding, and a chamfered surface of the substrate to be inspected to be inspected and an outer peripheral side surface between the chamfered surfaces. At least one of them is moved to capture an image of the surface to be inspected of the substrate to be inspected so that relative movement occurs between the device and the inspection image. A method for inspecting a ground surface of a substrate edge, characterized by determining. 2. An operating device for rotating a disk-shaped substrate to be inspected whose outer peripheral edge is chamfered by edge grinding, and a chamfered surface of the substrate to be inspected as a surface to be inspected and an outer peripheral side surface between the chamfered surfaces. An imaging device for imaging at least one of them,
A ground surface of the substrate end portion, characterized in that the image of the substrate to be inspected output from the imaging device is compared with a reference image of a non-defective product to determine whether the appearance of the surface to be inspected is good or bad. Inspection equipment. 3. An imaging device for imaging at least one of a chamfered surface to be inspected and an outer peripheral side surface between the chamfered surfaces of the inspected substrate whose outer peripheral edge is chamfered by edge grinding. An actuating device that moves the substrate to be inspected so that the surface to be inspected passes through the imaging region of the imaging device, and an image of the substrate to be inspected output from the imaging device and a reference image of a non-defective substrate, An inspection device for a ground surface of a substrate end portion, comprising: a determination device for determining the quality of an external appearance. 4. An imaging device for imaging at least one of a chamfered surface to be inspected and an outer peripheral side surface between the chamfered surfaces of a substrate to be inspected whose outer peripheral edge is chamfered by edge grinding. And an actuating device for moving the imaging device along the surface to be inspected, and determining whether the appearance of the substrate to be inspected is good or bad by comparing the image of the substrate to be inspected output from the imaging device with a reference image of a non-defective product. An inspection device for a ground surface of a substrate edge, comprising: a device; 5. The inspection of a ground surface of a substrate edge according to claim 2, further comprising an illumination device for illuminating a defect on the surface to be inspected by illuminating an imaging region of the imaging device. apparatus.