JPH10160680A - Flaw detection device for measuring transparent substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily mount a crystal blank at a fixed position on a substrate mount stage, at placement of the crystal blank, and to easily release it from the substrate mount stage at picking up for transportation. SOLUTION: Relating to flaw inspection of a crystal blank 1, the crystal blank 1 is transported with a transportation robot arm 22 to a substrate mount stage 2 for optical inspection. On a mount surface of the substrate stage 2, flaws are generated with polishing particles of size of #800-1500, and then treated with hydrofluoric acid for forming a smooth rough 3. Thereby, the crystal blank 1 does not slide on the substrate mount stage 2 at mount, with tight- contact to the substrate mount stage 2 thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for inspecting a transparent substrate to be measured, such as a quartz crystal blank, which is placed on a substrate mounting table and optically inspects for flaws. The present invention relates to a flaw inspection device that improves the transportability of a measurement transparent substrate.

[0002]

2. Description of the Related Art A quartz resonator is formed from a quartz blank. However, even if there is a slight flaw in the quartz blank, the quartz resonator becomes defective, and therefore, the detection of a scratch on the quartz blank is very important. .

Hitherto, humans have inspected the scratches on the quartz blank visually, but since it relies on visual inspection, it has been very difficult to detect scratches (defects) of several tens of μm or less. In addition, since the work is performed continuously for a long time, the fatigue of the worker is also severe, and as a result, a stable inspection result cannot be obtained,
It was a state where two people and three people performed the test in duplicate.
Therefore, a flaw inspection device using image processing has been demanded.

[0004] As a conventional flaw inspection apparatus by image processing, for example, there is one described in Japanese Patent Application Laid-Open No. 7-103905 (hereinafter simply referred to as "publication").

[0005] As shown in FIG.
Lights 41 to 43 are arranged at different positions to irradiate the inspection object 40 such as a quartz blank from three directions, and CCD cameras 44 to 45 are arranged between the illuminations.
The CCD cameras 44 to 45 and the illuminations 41 to 43 are arranged at positions at an angle of 45 ° with respect to the horizontal plane of the inspection object 40. To inspect for flaws, one out of two cameras and one out of three lights are turned on simultaneously and the others are turned off.
The four combinations of ON and OFF are performed, and four images are captured by the cameras 44 to 45 to cover the detection range of 360 °. Each image is stored in the image input means 46,
The feature extraction means 4 for each of these image signals
7. Judgment is made via the pass / fail judgment means 48 to detect a defect such as a scratch which does not depend on the crack direction.

However, the above-mentioned prior art has the following problems.

[0007] Since irradiation and imaging are performed from a diagonal direction using a plurality of illuminations and cameras, focusing and setting of light conditions cannot be set to the same level for all images, and accurate detection cannot be performed. .

[0008] Since the camera is installed obliquely, the image becomes elliptical, and accurate measurements and measurements cannot be made. In order to accurately measure and measure dimensions, complicated correction processing is required.

[0009] Since the camera and the illumination are switched, the control is complicated. In addition, a large number of images are required to inspect one inspection object, the detection algorithm is complicated, and the image processing speed cannot be increased.

[0010] Both the camera and the lighting are 4
Since it is arranged at a position having an angle of 5 °, there is a possibility that the base pattern of the mounting table on which the inspection object is placed may be input. When the base pattern of the mounting table is input, the S / N ratio of the image of the scratch or the defect becomes worse, and there is a possibility that the detection becomes difficult.

Therefore, in order to solve these problems, scattered light is irradiated at an irradiation angle within a range of ± 30 ° from the entire circumferential direction of the side surface of the inspection object such as a quartz blank to the inspection object surface. In addition, a flaw inspection apparatus that captures an image from directly above a surface of an object to be inspected has been studied. According to this, light is emitted from all around the side surface of the object to be inspected, and since the light is scattered light, the reflected light reflected at the scratch or edge is emphasized, and only the scratch or edge is imaged. Emerge clearly above. Since the light is not radiated from the front and back surfaces of the object to be measured, light that simply passes through the object to be inspected or is reflected on the surface is not imaged, so that the entire image of the object to be inspected does not appear as a shadow.
The light to be imaged is only a scratch existing on the inspection object or reflected light reflected by a side surface (edge) of the inspection object. By performing image processing on the reflected light, flaws can be easily inspected.

[0012]

However, since a quartz blank cannot be used if it has scratches, it is not a sampling test,
100% inspection is required. In view of the rapid increase in demand for crystal blanks in recent years, automation and speeding-up are indispensable in the flaw inspection apparatus studied above. In this case, transport of the crystal blank to the substrate mounting table becomes a bottleneck.
Since both the crystal blank and the substrate mounting table are mirror-finished, a single air layer is formed between the crystal blank and the substrate mounting table during mounting, and the crystal blank slides on the substrate mounting table or This is because the air layer is removed and may be in close contact with the substrate mounting table.

Therefore, it has been studied to roughen the mounting surface of the substrate mounting table by polishing or the like so that the quartz crystal blank does not slip and does not adhere to the surface so that the surface is uneven. However, the degree of surface roughening of the mounting surface of the mounting table has not yet been sufficiently studied. For this reason, even if the mounting table is simply provided with irregularities, the transparent substrate to be measured slides on the substrate mounting table when the transparent substrate to be measured transferred by the transfer robot arm of the automation device is mounted on the substrate mounting table. The mounting position was unstable and unstable, and precise measurement could not be performed. Also,
After the placement, the transfer robot arm comes into close contact with the substrate mounting table, and the pick-up by the transfer robot arm after the inspection may not work well. This phenomenon is remarkable when the transparent substrate to be measured is a quartz blank having a thickness of 30 μm to 500 μm and a side or diameter of 3 mm to 50 mm.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for inspecting a transparent substrate to be measured for flaws by transporting the transparent substrate to be measured to a substrate mounting table. An object of the present invention is to provide a flaw inspection apparatus which improves the transportability of a measurement transparent substrate.

[0015]

According to the present invention, a transparent robot is transported to a substrate mounting table by a transport robot to optically inspect the scratches, and after the inspection, the transparent substrate to be transported again by the transport robot is inspected. In the flaw inspection device, the mounting surface of the substrate mounting table is scratched with abrasive particles having a particle size of 800 to 1500 and processed with acid to form smooth unevenness.

Since the uneven surface is provided on the mounting surface of the substrate mounting table, a discontinuous air layer is formed between the transparent substrate and the transparent substrate, so that air can freely flow in and out of the substrate. By simply mounting the substrate on the substrate mounting table, positioning according to the accuracy of the transfer robot is performed without sliding. Since the air layer is maintained even after the mounting, the transparent substrate to be measured does not adhere to the substrate mounting table. At the time of pickup, air is introduced from the outside between the substrate mounting table and the transparent substrate to be measured, so that the transparent substrate to be measured can be easily separated from the substrate mounting table.

Further, since the unevenness is smoothed, even when the hardness of the transparent substrate to be measured is higher than that of the substrate mounting table, the surface is not damaged by the transparent substrate to be measured. To form the desired irregularities, the surface is scratched with abrasive particles and then treated with an acid. In this case, the particle size of the abrasive particles is 800 to 150.
0 is good. If the particle size of the abrasive particles is smaller than 800, the uneven surface becomes sharp and thus may be judged as a scratch at the time of inspection. If the particle size is larger than 1500, the unevenness disappears and slip and adhesion are likely to occur. .

In particular, when the transparent substrate to be measured is a quartz crystal blank, if the transparent substrate mounting table is made of hard quartz glass, the substrate mounting table is hardly damaged by the substrate, and the handling becomes easy.

The transparent substrate to be inspected of the present invention includes a video camera and a D
A VD crystal lens or the like is included.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a flaw inspection apparatus for a transparent substrate to be measured according to the present invention is applied to a quartz blank for a quartz oscillator will be described below with reference to the drawings. FIG. 1 is a conceptual diagram of the device.

In FIG. 1, reference numeral 1 denotes a mirror-finished strip-shaped quartz blank, usually having a long side of 3 mm to 50 m.
m and a thickness of about 30 μm to 500 μm. The shape of the crystal blank 1 is not limited to a strip shape, but may be a circle or another shape.

A mirror-finished quartz glass plate is also used for the substrate mounting table 2 on which the crystal blank 1 is mounted. The reason why a mirror-finished quartz glass plate is used for the mounting table 2 is to increase the SN ratio and increase the inspection accuracy. The hard quartz glass was used to prevent the quartz blank 1 from scratching. The back surface of the quartz blank 1 remains mirror-finished, but the surface serving as the mounting surface of the quartz blank 1 has smooth irregularities 3 in order to avoid sliding and adhesion of the quartz blank 1.
Is attached.

A ring light 5 for irradiating light toward the entire periphery of the side surface of the quartz blank 1 is disposed below the mounting table 2.
The reason why the ring light 5 is arranged below the substrate mounting table 2 is that
This is to prevent an obstacle from coming to the upper side when moving the crystal blank 1 and to cope with automation of the inspection process and mass production.

As the ring light 5, a simple and inexpensive annular fluorescent lamp can usually be used. When a fluorescent lamp is used for the ring light 5, the light emitted from the fluorescent lamp is already scattered light, so the diffuser 4 is not essential, but in order to further enhance the scattering effect, in the irradiation direction of the ring light 5, It is preferable to dispose a ring-shaped diffusion plate 4 for diffusing light emitted from the ring light 5 to the crystal blank 1 and irradiating the crystal blank 1 with scattered light. A neutral density filter is used for the diffusion plate 4.

In general, the crystal blank is gradually increased in transparency by polishing. When the surface is slightly clouded after being polished with abrasive particles of about 2000 to 4000, the light is reduced using the diffusion plate 4 so that the scratches are more easily floated. On the contrary, when the abrasive particles have a transparent finish of 4000 or more, the light is intensified to emphasize the scratches.

A light-shielding plate 6 for shielding a part of the ring light 5 that does not want to contribute to the irradiation is provided around the ring light 5 at an irradiation angle θ in the range of 0 ° to −30 ° with respect to the surface of the quartz blank 1. Light can be emitted from the entire circumferential direction of the side surface of the quartz blank 1. Irradiation angle is crystal blank 1
Is negative on the back side.

The image pickup means 11 is arranged at a position directly above the surface of the crystal blank 1 in a direction perpendicular to the image pickup direction. Imaging means 1
1 is set so that, for example, a CCD camera 13 and a microscope 12 can be used, and only the vicinity of the crystal blank is included in the field of view.

The image pickup means 11 and the ring light 5 are respectively controlled by the image input means 14, and the image signals picked up by the image pickup means 11 are passed through the image input means 14 and the feature extraction means 15, and are judged by the judgment means 16.
Is input to Since the imaging means 11 only fits the vicinity of the crystal blank in the field of view, the change in the brightness of the field of view can be image-processed and detected at high speed.

The crystal blank 1 is a vacuum chuck 2
1 and is transferred to the substrate mounting table 2 by the transfer robot arm 22 after the transfer robot arm 22 and inspected for flaws.
2 to be conveyed.

In the above-described configuration, the transfer robot arm 22 is attracted to the vacuum chuck 21 and sucked.
Crystal blank 1 transported to substrate mounting table 2 by
Is mounted at a predetermined position on the substrate mounting table 2. At this time, since the mounting surface of the substrate mounting table 2 is formed in an irregular shape with a predetermined roughness, it does not slip on the substrate mounting table and is accurately mounted at a fixed position. Precise measurement becomes possible.

When scattered light is emitted from the ring light 5 disposed below the substrate mounting table 2 toward the quartz blank 1,
The entire periphery of the side surface of the quartz blank 1 is wrapped by the scattered light. In this case, light should not be irradiated from directly above or directly below. When irradiated from directly above or below,
The image of quartz blank 1 is CCD by transmitted light or reflected light
This is because the image is reflected on the camera 13. In addition, the base pattern of the mounting table 2 supporting the crystal blank 1 is clearly seen, and it is difficult to determine a scratch (defect) existing in the crystal blank 1.

As shown in FIG. 2, when the crystal blank 1 is irradiated with light from the entire side surface, the reflected light energy at the scratches 31 or the defect portion or the edge processed portion of the crystal blank 1 increases. This is because the direction of light emitted from the periphery of the quartz blank 1 is omnidirectional in the horizontal direction due to scattering. If there is no defect in the crystal blank 1, the optical path is not blocked, and the scattered light passes through as transmitted light. On the other hand, if there is an edge or a flaw 31, the light hits there and becomes reflected light 33 and is emphasized.

When the scattered light 32 hits the flaw 31, it is reflected and a flaw appears on the surface of the quartz blank 1. Since the light 31 is radiated from all directions to the flaw 31, the energy of the reflected light of the flaw 31 is emphasized, and when viewed from above with the microscope 12 or the camera 13, the flaw 31 appears clearly floating. Crystal defects are:
Since it has all directions, when irradiating light in one direction, it is difficult to detect a scratch parallel to the light without reflection, and even when it irradiates light in three directions,
Since the ratio is poor, it is difficult to detect a flaw accurately. However, as in the present embodiment, the SN ratio can be remarkably improved by intensively irradiating the light from all sides and all directions to the flaw 31 and utilizing the synergistic effect of the light, so that even a small flaw can be accurately detected. It becomes possible to detect. In particular, it is possible to detect even a flaw (10 μm or less) that is difficult to detect with human eyes by relatively increasing the light amount.

Further, since an image can be taken and image-processed with the whole crystal blank as a field of view at a time, even a small flaw (10 μm or less) can be detected at high speed. For example, even if the image is processed as a 512 × 512 image, it can be detected at a speed of 200 ms or less.
The same is true for any number of scratches in a single crystal blank.

Further, even a small flaw of 10 μm or less has a large light energy and can be stably detected, so that it is easy to automate the image processing.

As a secondary effect, if the edge processing accuracy of the peripheral surface of the crystal blank is rough, the reflection of light at the edge portion increases. It can be applied to inspection of blank processing accuracy. Further, if the reflection on the edge processed surface is used, it can be applied to the measurement of the shape and dimensions of the quartz blank.

The light irradiation angle on the surface of the quartz blank is preferably in the range of 0 ° to -30 °. The reason for limiting to this range is that the S / N ratio is large until the irradiation angle is up to 30 °.
Can be clearly discriminated, but if it exceeds this, a large number of base patterns on the mounting table will appear, making the discrimination difficult.
In °, the image of the scratch 31 is completely absorbed by the underlying pattern, and the scratch 3
This is because 1 cannot be detected.

The crystal blank 1 having undergone the flaw inspection is again sucked by the vacuum chuck 21 and transported to the next step by the transport robot arm 22. At this time, since the unevenness 3 having a predetermined roughness is formed on the mounting surface of the substrate mounting table 2, the crystal blank 1 does not come into close contact with the substrate mounting table 2 and does not come off and can be picked up smoothly. , And smooth conveyance can be performed.

By the way, the above-mentioned irregularities 3 on the mounting surface of the substrate mounting table are formed as shown in FIG. 1.5mm thickness
Abrasive particles having a particle size of 800 to 1500 are applied to the surface of the quartz glass to form sharp irregularities 3a to form ground glass (FIG. 3 (a)). Then, it is treated with hydrofluoric acid to smooth the irregularities (FIG. 3 (b)). When ordinary soda glass is used, the hardness is increased by deoxidizing so as to be able to resist hard quartz. The transmittance is set to 60% or more in the deoxidized state. Note that the thickness of the substrate mounting table is preferably about 0.5 mm to 3 mm. If the thickness is 0.5 mm or less, it is too thin to work, and if it is 3 mm or more, it is too thick to be practical. The reason why the unevenness formed on the substrate mounting table is smoothed is as follows.

The crystal blank is irradiated with light through the substrate mounting table 2. If the unevenness is sharp, the scattered light becomes uneven due to the influence of refraction.

If the unevenness on the surface is sharp, it cannot be distinguished from a scratch on the quartz blank.

Since the quartz blank 1 is harder than quartz glass, if the unevenness is sharp, the quartz glass is easily damaged.

As described above, in the present embodiment, since the unevenness having the optimum roughness is provided on the mounting surface of the substrate mounting table, an air layer which induces sliding is formed between the mounting surface and the quartz crystal blank. Therefore, the crystal blank does not slide on the substrate mounting table. Therefore, only by lowering the transfer robot arm to release the suction, the crystal blank can be placed at a fixed position on the substrate mounting table, and an accurate flaw inspection can be performed. Further, there is no possibility that the air layer is completely expelled and the crystal blank 1 comes into close contact with the substrate mounting table 2. Therefore, the pickup after the inspection does not fail, and handling by the vacuum chuck can be performed at high speed.

[0044]

According to the present invention, irregularities having a predetermined roughness are provided on the mounting surface of the transparent substrate mounting table, so that the transparent substrate to be measured slides on the substrate mounting table during mounting. Disappears,
The mounting position on the substrate mounting table is stabilized. In addition, since the transparent substrate to be measured can be smoothly transported at the time of pickup since it does not adhere to the substrate mounting table, the inspection can be speeded up.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a flaw inspection apparatus for a transparent substrate to be measured according to the present invention.

FIG. 2 is an explanatory view showing the principle that a flaw rises when light is irradiated toward the entire periphery of a side surface of a crystal blank;
(A) is a plan view and (b) is a side view.

3A and 3B are process diagrams for forming irregularities on a mounting surface of a substrate mounting table, wherein FIG. 3A shows a state after sanding and FIG. 3B shows a state after hydrofluoric acid treatment.

FIG. 4 is a schematic configuration diagram of a conventional inspection apparatus for a flaw of a transparent substrate to be measured.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal blank (transparent substrate to be measured) 2 Substrate mounting table 3 Irregularity 5 Ring light 11 Imaging means 14 Image input means 15 Feature extraction means 16 Judgment means 22 Transfer robot arm

Claims (1)

[Claims] In a flaw inspection device for a transparent substrate to be measured, which is transported by a transport robot to a substrate mounting table to optically inspect the flaws after being inspected, and is inspected again by the transport robot after the inspection. 800 to 15 on the mounting surface of the table
A scratch inspection apparatus for a transparent substrate to be measured, characterized in that scratches are made with abrasive particles having a particle size of No. 00 and treated with acid to form smooth irregularities.