JP4679282B2 - Substrate inspection apparatus and substrate inspection method - Google Patents

Description

The present invention relates to a substrate inspection device and substrate inspection method for detecting defects in a glass substrate or a plastic substrate or the like used in the manufacture of display panels, to detect the front surface and internal defects, particularly a transparent substrate The present invention relates to a suitable substrate inspection apparatus and substrate inspection method.

  Manufacture of TFT (Thin Film Transistor) substrates, color filter substrates, plasma display panel substrates, organic EL (Electroluminescence) display panel substrates, etc. for liquid crystal display devices used as display panels is made by photolithography technology using glass substrates, This is performed by forming a pattern on a substrate such as a plastic substrate. At that time, if a defect such as a scratch or a foreign substance exists on the substrate, the pattern is not formed well, which causes a defect. For this reason, a defect inspection apparatus is used to inspect defects such as scratches and foreign matter on the substrate.

The defect inspection apparatus irradiates a substrate with inspection light such as a laser beam and receives reflected light or scattered light from the substrate to detect defects such as scratches or foreign matter on the substrate. As a method for determining whether a detected defect is a scratch or a foreign substance in an inspection of a glass substrate using a defect inspection apparatus, a technique described in Patent Document 1 is known. Moreover, the technique of patent document 2 is known as a method of identifying whether the detected defect exists in the front surface or the back surface of a glass substrate.
Japanese Patent Laid-Open No. 9-257642 JP-A-9-258197

  In the manufacturing process of a glass substrate, foreign substances may be mixed inside the glass substrate or bubbles may be generated. In the inspection by the defect inspection apparatus, such defects inside the glass substrate are detected together with defects on the surface of the glass substrate. Conventionally, it has been possible to determine air bubbles using the technique described in Patent Document 1 for the detected defects, but it has not been possible to discriminate foreign substances on the surface of the glass substrate from internal foreign substances.

  On the other hand, in Japanese Patent Application No. 2004-171605 by the present applicant, a first inspection step for receiving scattered light by adjusting the focal position of the optical system to the surface of the glass substrate, and the focal position of the optical system as the glass substrate. A second inspection step for receiving scattered light in accordance with the inside of the glass substrate, and from the difference in intensity between the scattered light received in the first inspection step and the scattered light received in the second inspection step, A glass substrate inspection method for discriminating between surface foreign substances and internal foreign substances has been proposed. This inspection method requires a plurality of inspection steps, and there has been a demand for an apparatus and method that can inspect defects on the surface and inside of the substrate more efficiently.

  An object of the present invention is to efficiently discriminate between defects on the surface of a substrate and internal defects in a single inspection process.

The substrate inspection apparatus of the present invention is a substrate inspection apparatus for detecting defects on the surface and inside of a transparent substrate used for manufacturing a display panel, and is disposed below the substrate, and the inspection light is obliquely directed to the back surface of the substrate. An inspection light projecting system that irradiates the substrate, scattered light that is disposed above the substrate, transmitted from the back surface of the substrate to the inside of the substrate, and reached the surface of the substrate is scattered by defects on the surface of the substrate ; and the scattered light inspection light transmitted into the interior of the substrate from the rear surface is disturbed lithium by the defects within the substrate of the substrate, a first light receiving system that receives focus on the surface of the substrate, above the substrate Arranged and transmitted from the back surface of the substrate to the inside of the substrate, the inspection light that has reached the surface of the substrate is scattered by defects on the surface of the substrate, and the inspection light that has been transmitted from the back surface of the substrate to the inside of the substrate internal lithium disturbed scattered light by the defect of the substrate A second light receiving system that receives focus on, to process the detection signals of the first light-receiving system and the second light receiving system to detect the surface or internal defects of the substrate, the first light receiving system the difference in strength between the scattered light received by the scattered light and the second light receiving system has received, if the intensity of the scattered light received by the first light receiving system is greater than the intensity of the scattered light received by the second light receiving system Determines that the detected defect is a defect on the surface of the substrate, and if the intensity of the scattered light received by the first light receiving system is smaller than the intensity of the scattered light received by the second light receiving system, the detected defect is the substrate. And a processing means for discriminating between the defects on the surface of the substrate and the internal defects.

The substrate inspection method of the present invention is a substrate inspection method for detecting defects on the surface and inside of a transparent substrate used for manufacturing a display panel, from an inspection light projection system disposed below the substrate. the inspection light is irradiated obliquely to the rear surface of the substrate, transmitted through the back surface of the substrate into the interior of the substrate, scattered light inspection light that has reached the surface of the substrate is scattered by defects on the surface of the substrate, and the back surface of the substrate the scattered light inspection light transmitted into the interior of the substrate is disturbed lithium by the internal defects of the substrate, the first when receiving focus on the surface of the substrate by the light receiving system arranged above the substrate at the same time, The second light receiving system disposed above the substrate receives light focused on the inside of the substrate, processes the detection signals of the first light receiving system and the second light receiving system, and detects defects on the surface or inside of the substrate. detecting the scattered light and the second light receiving by the first light receiving system has received From There difference in strength between the scattered light received, the intensity of the scattered light received by the first light receiving system is greater than the intensity of the scattered light received in the second light receiving system, the detected defects on the surface of the substrate If the intensity of the scattered light received by the first light receiving system is smaller than the intensity of the scattered light received by the second light receiving system, it is determined that the detected defect is a defect inside the substrate. It distinguishes between surface defects and internal defects.

In the first light receiving system, since the defects on the surface of the substrate are in focus, the light receiving efficiency of the scattered light is high, and the intensity of the scattered light received is large. Since the defects inside the substrate are not in focus, the light receiving efficiency of scattered light is low, and the intensity of the scattered light received is low. On the other hand, in the second light receiving system, since the defects on the surface of the substrate are not focused, the light receiving efficiency of the scattered light is low, and the intensity of the scattered light received is small. Since defects in the substrate are in focus, the light receiving efficiency of scattered light is high and the intensity of scattered light received is large. From the intensity differences between the first light receiving system is scattered light scattered light and the second light receiving system receiving has received, since the discrimination between defects and internal defects of the surface of the substrate, defects and internal surface of the substrate Are efficiently discriminated in a single inspection process.

Further, a substrate inspection device of the present invention, the first light receiving system is a lens group for inspection light focuses the scattered light disturbed lithium by the surface or internal defects of the substrate and the imaging lens group And a first light receiving element that receives one of the lights divided by the dividing means while focusing on the surface of the substrate, and the second light receiving system includes the lens. A group, the dividing unit, and a second light receiving element that receives the other of the lights divided by the dividing unit while focusing on the inside of the substrate.

The substrate inspection method of the present invention, the inspection light is to divide the light passing through the lens group to be condensed and imaging the scattered light disturbed lithium by the surface or internal defects of the substrate, a lens unit The dividing means is provided in common to the first light receiving system and the second light receiving system, and in the first light receiving system, one of the lights divided by the dividing means by the first light receiving element is focused on the surface of the substrate. The second light receiving system receives the other light divided by the dividing means by the second light receiving element while focusing on the inside of the substrate.

And inspection light focuses the lithium disturbed scattered light by the surface or internal defects of the substrate and the lens group for focusing, and a dividing means for dividing light passing through the lens group, the first light receiving system By providing them in common to the second light receiving system, an expensive lens group can be shared by the first light receiving system and the second light receiving system, and the apparatus configuration is simplified.

  According to the present invention, defects on the surface of a substrate and internal defects can be efficiently distinguished in a single inspection process.

Furthermore, according to the present invention, dividing means for inspection light to divide the light passing through the lens group to be condensed and imaging the scattered light disturbed lithium by the surface or internal defects of the substrate, a lens unit Are shared by the first light receiving system and the second light receiving system, so that the expensive lens group can be shared by the first light receiving system and the second light receiving system, and the device configuration can be simplified. can do.

  FIG. 1 is a diagram showing a schematic configuration of a substrate inspection apparatus according to an embodiment of the present invention. The present embodiment shows an example of a substrate inspection apparatus that detects defects on the surface or inside of a substrate from scattered light in which the inspection light is scattered by defects on the substrate. The substrate inspection apparatus includes an optical system 10, an XY movement mechanism 30, an XY movement control circuit 31, a focus adjustment mechanism 40, a focus adjustment control circuit 41, a signal conversion circuit 50, a signal processing circuit 60, a CPU 70, and an output device 80. It is configured.

  Optical systems 10 are arranged above and below a substrate 1 mounted on an inspection stage (not shown). The optical system 10 includes a focus adjustment light projection system for focus adjustment, an inspection light projection system that irradiates the substrate 1 with inspection light, a reflected light detection system for focus adjustment, and a light reception that receives scattered light from the substrate 1. It is configured to include the system. The focus adjusting light projecting system, the focus adjusting reflected light detecting system, and the light receiving system are disposed above the substrate 1, and the inspection light projecting system is disposed below the substrate 1.

  The focus adjustment light projecting system includes a laser light source 11 a, lenses 12 a and 13 a, and a mirror 14. The laser light source 11a generates laser light. The lens 12a condenses the laser light generated from the laser light source 11a. The lens 13 a focuses the laser light collected by the lens 12 a and irradiates the surface of the substrate 1 obliquely through the mirror 14. Since the laser light source irradiated to the surface of the substrate 1 from the focus adjustment light projecting system has a large incident angle, most of the light is reflected on the surface of the substrate 1.

  On the other hand, the inspection light projection system includes a laser light source 11b and lenses 12b and 13b. The laser light source 11b generates laser light serving as inspection light. The lens 12b condenses the inspection light generated from the laser light source 11b. The lens 13 b focuses the inspection light collected by the lens 12 b and irradiates the back surface of the substrate 1 obliquely. In the present embodiment, as an example, the incident angle θ of the inspection light with respect to the substrate 1 is about 10 degrees.

  The XY movement mechanism 30 moves the optical system 10 in the XY direction under the control of the XY movement control circuit 31. The XY movement control circuit 31 drives the XY movement mechanism 30 in accordance with a command from the CPU 70. By moving the optical system 10 in the X and Y directions, the inspection light irradiated from the inspection light projection system of the optical system 10 scans the surface of the substrate 1 and the entire substrate 1 is inspected.

  Instead of moving the optical system 10, the substrate 1 and the optical system 10 may be moved relatively by moving the inspection stage on which the substrate 1 is mounted in the XY directions.

  The reflected light detection system for focus adjustment includes a mirror 14, a lens 15, and a CCD line sensor 16. The reflected light from the substrate 1 enters the lens 15 via the mirror 14. The lens 15 focuses the reflected light from the substrate 1 and forms an image on the light receiving surface of the CCD line sensor 16.

At this time, the light receiving position of the reflected light on the light receiving surface of the CCD line sensor 16 varies depending on the height of the surface of the substrate 1. When the height of the surface of the substrate 1 shown in FIG. 1 is used as a reference and the height of the surface of the substrate 1 is lower than the reference , the laser light from the focus adjustment light projecting system is irradiated and reflected on the surface of the substrate 1. The position of the reflected light on the light receiving surface of the CCD line sensor 16 moves to the left side of the drawing. Conversely, when the height of the surface of the substrate 1 is higher than the reference, the position at which the laser light from the focus adjustment light projecting system is irradiated and reflected on the surface of the substrate 1 moves to the left side of the drawing, and the CCD line sensor 16 The light receiving position of the reflected light on the light receiving surface moves to the right side of the drawing.

  The CCD line sensor 16 outputs a detection signal corresponding to the intensity of the reflected light received by the light receiving surface to the focus adjustment control circuit 41. The focus adjustment control circuit 41 adjusts the focus so that the reflected light from the surface of the substrate 1 is received at the center position of the light receiving surface of the CCD line sensor 16 from the detection signal of the CCD line sensor 16 in accordance with a command from the CPU 70. The mechanism 40 is driven to move the optical system 10. The focus adjustment mechanism 40 is configured by, for example, a pulse motor, and adjusts the focus position by moving the optical system 10 up and down in accordance with the drive pulse from the focus adjustment control circuit 41.

  FIG. 2 is a diagram for explaining scattered light due to defects on the surface or inside of the substrate. Since the inspection light irradiated from the inspection light projection system to the back surface of the substrate 1 has a small incident angle, most of the inspection light is transmitted from the back surface of the substrate 1 to the inside of the substrate 1 as indicated by a solid line, and to the surface of the substrate 1. It reaches and is ejected from the surface of the substrate 1. When a defect exists in the substrate 1, a part of the inspection light transmitted into the substrate 1 is scattered by the defect, and scattered light indicated by a two-dot chain line is generated. When a defect exists on the surface of the substrate 1, part of the inspection light that has passed through the inside of the substrate 1 and reached the surface of the substrate 1 is scattered by the defect, and scattered light indicated by a broken line is generated.

  In FIG. 1, the light receiving system of the optical system 10 includes a first light receiving system and a second light receiving system. The first light receiving system includes a condenser lens 17, an imaging lens 18, a light shielding plate 19, a prism 20, and a CCD line sensor 21. On the other hand, the second light receiving system includes a condenser lens 17, an imaging lens 18, a light shielding plate 19, a prism 20, and a CCD line sensor 22. That is, in the present embodiment, the condenser lens 17, the imaging lens 18, the light shielding plate 19, and the prism 20 are provided in common for the first light receiving system and the second light receiving system.

  The condensing lens 17 condenses scattered light from the surface or the inside of the substrate 1. At this time, the light shielding plate 19 blocks the inspection light transmitted through the substrate 1 so as not to enter the lens 17. The imaging lens 18 images the scattered light collected by the condenser lens 17 on the position of the light receiving surface of the CCD line sensor 21. The prism 20 divides the light that has passed through the imaging lens 18 into two, irradiates one of the divided light to the CCD line sensor 21, and the other to the CCD line sensor 22. A half mirror may be used instead of the prism 20.

  The CCD line sensor 21 of the first light receiving system receives one of the lights divided by the prism 20 and outputs a detection signal corresponding to the intensity of the received scattered light to the signal conversion circuit 50. Here, the CCD line sensor 21 is disposed at a position where the light receiving surface is an image plane with respect to the surface of the substrate 1. That is, the first light receiving system is focused on the surface of the substrate 1.

  On the other hand, the CCD line sensor 22 of the second light receiving system receives the other of the lights divided by the prism 20 and outputs a detection signal corresponding to the intensity of the received scattered light to the signal conversion circuit 50. Here, the CCD line sensor 22 is configured such that the distance from the prism 20 is different from that of the CCD line sensor 21. Thereby, the light receiving surface of the CCD line sensor 22 is not the surface of the substrate 1 but an image surface with respect to a surface of a predetermined depth inside the substrate 1. That is, the second light receiving system is focused inside the substrate 1.

  The signal conversion circuit 50 converts the detection signals of the CCD line sensors 21 and 22 into digital signals and outputs them to the signal processing circuit 60. The signal processing circuit 60 includes an internal memory, and stores the digital signal input from the signal conversion circuit 50 in the internal memory as digital data. Then, the signal processing circuit 60 processes the digital data stored in the internal memory under the control of the CPU 70 to detect defects on the surface of the substrate 1 or inside.

  Subsequently, the signal processing circuit 60 performs surface / internal determination on the detected surface or internal defect of the substrate 1 from the digital data stored in the internal memory. This will be described with reference to FIG. FIG. 3 is a diagram for explaining the operation of the substrate inspection apparatus according to the embodiment of the present invention. FIG. 3A shows a state in which the first light receiving system detects scattered light, and FIG. 3B shows a state in which the second light receiving system detects scattered light. 3A and 3B, the condenser lens 17, the imaging lens 18, and the prism 20 of FIG. 3B shows the optical path of the scattered light without refraction by the prism 20 for comparison with FIG.

  As shown in FIG. 3A, in the first optical system, the defect on the surface of the substrate 1 is in focus, so the light receiving efficiency of the scattered light shown by the broken line is high, and the light received by the CCD line sensor 21 is received. The intensity of scattered light received by the surface is large. Since the defects inside the substrate 1 are not in focus, the light receiving efficiency of the scattered light indicated by the two-dot chain line is low, and the intensity of the scattered light received by the light receiving surface of the CCD line sensor 21 is low.

  On the other hand, as shown in FIG. 3B, in the second optical system, the defect on the surface of the substrate 1 is not focused, so the light receiving efficiency of scattered light indicated by the broken line is low, and the CCD line sensor 22 The intensity of scattered light received by the light receiving surface is small. Since the defect inside the substrate 1 is in focus, the light receiving efficiency of the scattered light indicated by the two-dot chain line is high, and the intensity of the scattered light received by the light receiving surface of the CCD line sensor 22 is high.

  Therefore, when the intensity of the scattered light received by the first optical system is F1, and the intensity of the scattered light received by the second optical system is F2, the surface defect of the substrate 1 is F1> F2, and the substrate 1 F1 <F2 for the internal defects. In the present embodiment, when F1> F2, the detected defect is determined as a defect on the surface of the substrate 1, and when F1 <F2, the detected defect is determined as a defect inside the substrate 1. The signal processing circuit 60 stores the surface / internal determination result data in the internal memory in association with the already stored detection result data.

  Finally, the CPU 70 outputs the inspection result to the output device 80 including a display, a printer, and the like based on the detection result data and the surface / internal determination result data stored in the internal memory of the signal processing circuit 60. As the output of the inspection result, for example, the position of the surface defect and the position of the internal defect may be displayed on separate maps. When only the surface defect is to be inspected, only the surface defect is displayed, and the internal defect position is displayed. If it is desired to inspect only the defects, only the internal defects may be displayed.

  According to the embodiment described above, the first light receiving system that receives the scattered light focused on the surface of the substrate, and the second light receiving system that receives the scattered light focused on the inside of the substrate. The difference between the intensity of the scattered light received by the first light receiving system and the scattered light received by the second light receiving system is used to discriminate defects on the surface of the substrate from internal defects, thereby Defects and internal defects can be distinguished efficiently in a single inspection process.

  Furthermore, according to the present invention described above, the lens group for condensing and forming the image of the scattered light, and the prism and the half mirror for dividing the light that has passed through the lens group, the first light receiving system and the second light receiving system. By providing the light receiving system in common, an expensive lens group can be shared by the first light receiving system and the second light receiving system, and the apparatus configuration can be simplified.

It is a figure which shows schematic structure of the board | substrate inspection apparatus by one embodiment of this invention. It is a figure explaining the scattered light by the surface or internal defect of a board | substrate. It is a figure explaining operation | movement of the board | substrate inspection apparatus by one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 10 Optical system 11a, 11b Laser light source 12a, 12b, 13a, 13b Lens 14 Mirror 15 Lens 16 CCD line sensor 17 Condensing lens 18 Imaging lens 19 Light-shielding plate 20 Prism 21, 22 CCD line sensor 30 XY moving mechanism 31 XY movement control circuit 40 focus adjustment mechanism 41 focus adjustment control circuit 50 signal conversion circuit 60 signal processing circuit 70 CPU
80 output device

Claims (6)

A substrate inspection apparatus for detecting defects on the surface and inside of a transparent substrate used for manufacturing a display panel,
An inspection light projection system that is disposed below the substrate and irradiates the inspection light obliquely to the back surface of the substrate;
Arranged above the substrate and transmitted from the back surface of the substrate to the inside of the substrate, the inspection light reaching the surface of the substrate was scattered by the defects on the surface of the substrate and transmitted from the back surface of the substrate to the inside of the substrate. the inspection light is scattered light disturbed lithium by the defects within the substrate, a first light receiving system that receives focus on the surface of the substrate,
Arranged above the substrate and transmitted from the back surface of the substrate to the inside of the substrate, the inspection light reaching the surface of the substrate was scattered by the defects on the surface of the substrate and transmitted from the back surface of the substrate to the inside of the substrate. the inspection light is disturbed lithium by the internal defects of the substrate scattered light, a second light receiving system that receives focus in the substrate,
The detection signals of the first light receiving system and the second light receiving system are processed to detect defects on the surface or inside of the substrate, and the scattered light received by the first light receiving system and the second light receiving system. If the intensity of the scattered light received by the first light receiving system is greater than the intensity of the scattered light received by the second light receiving system, the detected defect is detected on the substrate. If the intensity of the scattered light received by the first light receiving system is smaller than the intensity of the scattered light received by the second light receiving system, it is determined that the detected defect is a defect inside the substrate. And a processing means for discriminating defects on the surface of the substrate from internal defects. A focusing light projecting system that is disposed above the substrate and irradiates the surface of the substrate obliquely with a laser beam;
A reflected light detection system for focus adjustment, which is disposed above the substrate and receives the reflected light reflected from the surface of the substrate by the laser light emitted from the focus adjustment light projecting system;
The first light receiving system and the second light receiving system are moved up and down according to the light receiving position of the reflected light received by the reflected light detection system, and the focal point of the first light receiving system is set on the surface of the substrate. The substrate inspection apparatus according to claim 1, further comprising: a focus adjustment unit that adjusts a focus of the second light receiving system to the inside of the substrate. The first light receiving system is split inspection light is divided into a lens group to be condensed and imaging the scattered light disturbed lithium by the surface or internal defects of the substrate, the light passing through the lens And a first light receiving element that receives one of the lights divided by the dividing means while focusing on the surface of the substrate,
The second light receiving system includes the lens group, the dividing unit, and a second light receiving element that receives the other light divided by the dividing unit while focusing on the inside of the substrate. The substrate inspection apparatus according to claim 1 or 2 . A substrate inspection method for detecting defects and internal defects on a transparent substrate used for manufacturing a display panel,
From the inspection light projection system located below the substrate , irradiate the back of the substrate obliquely with the inspection light,
The inspection light transmitted from the back surface of the substrate to the inside of the substrate and reaching the surface of the substrate is scattered by defects on the surface of the substrate, and the inspection light transmitted from the back surface of the substrate to the inside of the substrate is inside the substrate . the scattered light is disturbed lithium by the defects, and simultaneously receiving focus on the first surface of the substrate by the light receiving system arranged above the substrate, the second light receiving system arranged above the substrate Receive light focused on the inside of the board,
Processing detection signals of the first light receiving system and the second light receiving system to detect defects on the surface or inside of the substrate;
The difference in strength between the first scattered light scattered light and the second light receiving system having received the light receiving system has received, scattering intensity of the scattered light received by the first light receiving system has received the second light receiving system If the intensity is greater than the intensity of the light, the detected defect is determined as a defect on the surface of the substrate, and if the intensity of the scattered light received by the first light receiving system is less than the intensity of the scattered light received by the second light receiving system A substrate inspection method characterized by discriminating a detected surface defect from an internal defect by determining the detected defect as a defect inside the substrate. From the focus adjustment light projecting system located above the substrate, irradiate the surface of the substrate obliquely with laser light,
The reflected light reflected by the surface of the substrate is received by the reflected light detection system for focus adjustment arranged above the substrate,
The first light receiving system and the second light receiving system are moved up and down according to the light receiving position of the reflected light received by the reflected light detection system, the first light receiving system is focused on the surface of the substrate, and the second 5. The substrate inspection method according to claim 4, wherein the light receiving system is focused on the inside of the substrate. And inspection light focuses the lithium disturbed scattered light by the surface or internal defects of the substrate and the lens group for focusing, and a dividing means for dividing light passing through the lens group, the first light receiving system And common to the second light receiving system,
In the first light receiving system, one of the lights divided by the dividing means by the first light receiving element is focused on the surface of the substrate and received.
6. The substrate inspection according to claim 4 , wherein the second light receiving system receives the other light divided by the dividing means by the second light receiving element while focusing on the inside of the substrate. Method.

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