JP2013079902A - Method and device for inspecting defect of glass substrate, and defect inspection system of glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow detection of not only defects such as a foreign matter and a scratch on a surface but also a defect due to a local variation in the thickness of a substrate.SOLUTION: A glass substrate inspection device comprises: a first defect detecting optical system which detects light transmitted through a glass substrate; a second defect detecting optical system which detects scattered light generated on a surface of or inside the glass substrate by the light transmitted through the glass substrate; and signal processing means which processes a signal detected by the first detecting optical system and a signal detected by the second detecting optical system. The signal processing means detects a defect caused by a local variation of the thickness of the glass substrate by inputting and processing the detection signal from first detecting optical system means, and detects a defect of the glass substrate by inputting and processing the detection signal from second detecting optical system means.

Description

  The present invention relates to a substrate inspection method and apparatus for detecting foreign matter and defects in a glass substrate used for manufacturing display panels and the like, and a glass substrate defect inspection system.

  Manufacturing of a TFT (Thin Film Transistor) substrate, a color filter substrate, and an organic EL (Electro Luminescence) substrate used as a display panel includes a step of forming a pattern on the substrate by photolithography. At that time, if there is a defect such as adhesion of a foreign substance or a scratch on the glass substrate, the pattern is not formed satisfactorily, resulting in a defective pattern and a decrease in yield. For this reason, conventionally, an inspection for detecting a foreign object, a defect, or the like using a defect inspection apparatus has been performed.

  As a method for detecting foreign matters and defects on an optically transparent sample (substrate), Patent Document 1 discloses an optical system for irradiating a surface of an inspection object to detect scattered light on the surface and a back surface of the inspection object. A method for detecting scattered light by light that has been irradiated with a laser and transmitted through an inspection object is disclosed.

  Further, in Patent Document 2, light that has passed through an intermittent slit is irradiated from the back surface of a glass substrate, light that has passed through the glass substrate is detected by a CCD image sensor, and a gentle circular shape on a glass substrate called a crater is disclosed. It is described that the presence or absence of protrusions is inspected.

JP 2007-24733 A JP 2002-286656 A

  Patent Document 1 discloses a detection system that irradiates light on the back surface of a substrate from an oblique direction and focuses the light transmitted through the substrate on the surface of the substrate and a detection system that aligns the focus position on the inside of the substrate. There is described a configuration of a defect inspection apparatus that detects and detects defects such as scratches and foreign matter on the surface of the substrate and defects inside the substrate.

  In general, in the process of processing TFT substrates, color filter substrates, and organic EL substrates that perform high-definition display, it is important to minimize the local thickness variation of each substrate to prevent display unevenness. become. For that purpose, in addition to the inspection of the surface and the inside of the substrate, a defect in which the thickness of the substrate is locally changed (a locally thinned portion or a locally thickened portion. This is called a crater defect).

  However, Patent Document 1 does not give consideration to detecting a defect (crater defect) in which the thickness of the substrate locally changes.

  On the other hand, Patent Document 2 describes that a defect (crater defect) in which the thickness of the substrate is locally changed is detected, but scratches on the surface of the glass substrate, bubbles in the glass substrate, There is no description about detecting defects such as foreign matter.

  The present invention solves the problems of the prior art and enables glass substrate defects to detect and identify not only defects such as foreign matter and scratches, but also defects in which the thickness of the substrate changes locally. An inspection method and apparatus, and a glass substrate defect inspection system are provided.

  In order to achieve the above-described object, the present invention adopts not only an inspection method based on dark field detection in which a laser is obliquely illuminated to detect scattered light from a foreign object or scratch, but also bright field detection using LED illumination. By doing so, it became possible to detect not only the surface foreign matter / defects but also defects caused by local changes in the thickness of the substrate called craters.

  That is, in order to achieve the above-described object, in the present invention, the glass substrate inspection apparatus includes a first defect detection optical system that detects light transmitted through the glass substrate, and the surface of the glass substrate by light transmitted through the glass substrate. Or a second defect detection optical system for detecting scattered light generated inside, and a signal processing means for processing a signal detected by the first detection optical system and a signal detected by the second detection optical system. The first defect detection optical system includes a first illumination light irradiating unit that irradiates illumination light on the back surface of the glass substrate, and a glass substrate irradiated with the illumination light by the first illumination light irradiating unit. And a first detection optical system that detects the image of the surface of the glass substrate by condensing and forming the transmitted light, and the second defect detection optical system obliquely illuminates the illumination light on the back surface of the glass substrate. Second illumination light irradiating means for irradiating from the direction, and this first And second detection optical system means for collecting and forming an image of the scattered light generated from the glass substrate irradiated with the illumination light by the illumination light irradiating means, and detecting an image of the surface of the glass substrate. The means detects a defect caused by a change in the local thickness of the glass substrate by inputting a detection signal from the first detection optical system means and processes it, and detects from the second detection optical system means. A defect of the glass substrate was detected by inputting and processing the signal.

  In order to achieve the above-described object, in the present invention, the glass substrate inspection method detects the first light transmitted through the glass substrate by the first defect detection optical system, and the second defect detection optical system. The scattered light generated on the surface or inside of the glass substrate is detected by the second light transmitted through the glass substrate, and the signal detected by the first detection optical system and the signal detected by the second detection optical system are Inspecting the glass substrate by processing, detecting the first light transmitted through the glass substrate with the first defect detection optical system, irradiating the back surface of the glass substrate with the first illumination light, The light transmitted through the glass substrate irradiated with the first illumination light is collected and imaged to detect an image on the surface of the glass substrate, and transmitted through the glass substrate with the second defect detection optical system. Generated on the surface or inside of the glass substrate by the second light To detect the scattered light, the second illumination light is irradiated on the back surface of the glass substrate from an oblique direction, and the scattered light generated from the glass substrate irradiated with the second illumination light is condensed and imaged. Detecting the image of the surface of the glass substrate, inspecting the glass substrate by processing the signal detected by the first detection optical system and the signal detected by the second detection optical system; A defect caused by a local thickness change of the glass substrate is detected by inputting a detection signal from the detection optical system means and processed, and a detection signal from the second detection optical system means is input and processed. This is done by detecting defects in the glass substrate.

  Furthermore, in order to achieve the above-described object, in the present invention, a glass substrate defect inspection system includes a transfer line, a glass substrate mounting means for mounting a glass substrate, and the glass substrate mounting means being transferred along the transfer line. And a glass substrate defect inspection means installed at a plurality of locations on the transfer line, and the glass substrate defect inspection means installed at a plurality of locations on the transfer line respectively inspect different areas of the glass substrate. Each of the glass substrate defect inspection means detects the light transmitted through the glass substrate illuminated by the first illumination unit and the first illumination unit that irradiates the glass substrate with the first illumination light. A first defect detection optical unit having a first detection optical system unit, a second illumination unit for irradiating the glass substrate with the second illumination light, and illumination by the second illumination unit A second defect detection optical unit having a second detection optical system unit for detecting light transmitted through the glass substrate, and a signal detected by the first detection optical system to process a local of the glass substrate A signal processing unit that detects a defect due to a change in thickness and processes a signal detected by the second detection optical system unit to detect a surface and an internal defect of the glass substrate is provided.

  According to the present invention, it is possible to detect not only foreign matter / defects on the surface of the inspection object but also defects (crater defects) in which the thickness of the substrate is locally changed.

It is a top view of a glass substrate defect inspection system. It is a front view of a glass substrate defect inspection system. It is a front view of an optical inspection device. It is a flowchart which shows the flow of the process of the defect inspection in an optical inspection apparatus. It is the figure which showed the state in which the image of the flaw defect was projected on the pixel of a CCD image sensor, and the output waveform of the CCD image sensor at that time. It is the figure which showed the state in which the image of the foreign material defect was projected on the pixel of a CCD image sensor, and the output waveform of the CCD image sensor at that time. It is the figure which showed the state in which the image of the dirt was projected on the pixel of a CCD image sensor, and the output waveform of the CCD image sensor at that time. It is the figure which showed the state in which the image of the crater was projected on the pixel of a CCD image sensor, and the output waveform of the CCD image sensor at that time. It is a flowchart which shows the flow of the process which identifies a foreign material and a defect. It is a flowchart which shows the flow of the process which classifies a glass substrate according to a grade.

An embodiment of the present invention will be described below with reference to the drawings.
1A and 1B show a configuration of a glass substrate defect inspection system according to an embodiment of the present invention.

  FIG. 1A is a plan view showing an overall configuration of a glass substrate defect inspection system 100 according to an embodiment of the present invention. FIG. 1B is a front view of the glass substrate defect inspection system 100.

  In FIG. 1A, 110 is a transfer line, 112 is a guide rail, 120 is a first transfer stage, 130 is a second transfer stage, 140 to 143 are optical inspection apparatuses, 180 is an overall control unit, and 190 is an air supply source. It is. Reference numeral 10 denotes a glass substrate to be inspected.

  In the front view of the glass substrate defect inspection system 100 shown in FIG. 1B, the first transfer stage 120 is driven by a linear motor 121 and moves along the guide rail 112. Thereby, the glass substrate 10 mounted on the first transfer stage 120 is transferred along the air floating surface 111 of the transfer line 110. 131 (151) is a linear motor that drives the second (3) transfer stage 130 (150), 161 is a linear motor that drives the fourth transfer stage 160, and 171 is a linear motor that drives the fifth transfer stage 170. It is.

  The glass substrate 10 to be inspected is increased in size and has a different size depending on the type, and the glass substrate having various sizes is inspected by one glass substrate defect inspection system 100. In order to inspect the entire surface of a large glass substrate 10 having such a different size with one optical inspection apparatus, the optical inspection apparatus must be matched to the largest glass substrate, and the size is increased. Throughput decreases.

  Therefore, in the inline-type glass substrate defect inspection system 100 shown in FIGS. 1A and 1B according to the present invention, the inspection region of the glass substrate 10 is divided into a plurality of sizes so that it can correspond to the sizes of various glass substrates. The divided areas are sequentially inspected by a plurality of optical inspection apparatuses 140 to 143 installed along the transport line.

  As described above, in the configuration in which the plurality of optical inspection apparatuses 140 to 143 are arranged along the transport line 110, it is important to reduce the waiting time of each of the inspection apparatuses 140 to 143 as much as possible in order to increase the line throughput. Become. In this embodiment, a plurality of substrate transfer stages 120, 130, 150, 160, 170... Are arranged between the inspection apparatuses 140 to 143 so that the substrates transferred on the respective transfer stages are alternately inspected. The waiting time of each of the inspection apparatuses 140 to 143 is made as small as possible.

  That is, in the present embodiment, in the configuration shown in FIGS. 1A and 1B, the glass substrate 10 to be inspected is placed on the air floating surface 111 of the inline transport unit 110 by the first transport stage 120 or the second transport stage 130. The optical inspection unit 140 detects scratches and defects on the surface. The glass substrate 10 that has been inspected in a predetermined area by the optical inspection unit 140 is the first substrate transfer unit 211 between the adjacent optical inspection unit 141 and the first transfer stage 120 or the second transfer. The substrate 130 is transferred from the stage 130 to the third transfer stage 150 or 160 using a substrate transfer means (not shown). Reference numerals 210 and 212 also denote substrate transfer units.

  FIG. 2 shows the configuration of the optical inspection apparatus 140 according to this embodiment. The optical inspection apparatus 140 controls the defect detection unit 200, the light source control unit 210, the signal processing unit 220, the stage control unit 230, and the defect detection unit 200, the light source control unit 210, the signal processing unit 220, and the stage control unit 230. CPU240 to be configured. The defect detection unit 200 includes two optical units, a crater detection optical unit 300 and a flaw defect detection optical unit 320.

  The crater detection optical unit 300 employs a bright field detection optical system, and condenses the LED light source 301 that irradiates illumination light from the back side of the glass substrate 10 to be inspected and the illumination light that has passed through the glass substrate 10. An imaging lens 312 that forms an image of the light transmitted through the glass substrate 10 condensed by the lens “311” and the condensing lens “311”, and the light transmitted through the glass substrate 10 formed by the imaging lens 312. A one-dimensional image sensor (line sensor) 313 such as a CCD for detecting an image of a linear region at the center of the illumination region in the surface image is provided. With such a configuration, the light emitted from the LED light source 301 is applied to the glass substrate 10 from below, and the scattered light is collected by the lens “311” to collect the one-dimensional CCD image sensor 313 (in the configuration of FIG. A crater defect is detected in a vertical direction (one-dimensional detection pixels are arranged in the Y direction).

  The flaw defect detection optical unit 320 employs a dark field detection optical system, and includes a light projecting unit 3210, a first light receiving system 3220, and a second light receiving system 3230. The flaw defect detection optical unit 320 is actually installed in a direction rotated by 90 ° about the optical axis of the detection system with respect to FIG. 2, but for the sake of simplicity, as shown in FIG. displayed.

  The light projecting unit 3210 is disposed on the back side of the glass substrate 10 and includes a laser light source 3211, a condenser lens 3212, a converging lens 3213, and a mirror 3214. The laser light source 3211 generates a laser that serves as inspection light. The condensing lens 3212 condenses the inspection light generated from the laser light source 3211. The converging lens 3213 focuses the inspection light collected by the condensing lens 3212. The mirror 3214 reflects the inspection light transmitted through the condenser lens 3212 to fold the optical path of the inspection light and irradiate the back surface of the substrate 10 obliquely. At this time, the illumination area of the glass substrate 10 is a long area along the incident direction (Y direction) of the illumination light.

  In the configuration of the light projecting unit 3210 illustrated in FIG. 2, the configuration in which the optical path of the inspection light emitted from the laser light source 3211 is bent by the mirror 3214 and the back surface of the glass substrate 10 is irradiated from an oblique direction has been described. 3214 is abolished, and the laser light source 3211, the condensing lens 3212, and the converging lens 3213 are disposed obliquely, and the inspection light emitted obliquely from the laser light source 3211 is irradiated to the back surface of the glass substrate 10 from the oblique direction. May be.

  The first light receiving system 3220 includes a condenser lens 3221, an imaging lens 3222, a light shielding plate 3223, a beam splitter 3224, and a CCD line sensor 3225. On the other hand, the second light receiving system 3230 includes a condenser lens 3221, an imaging lens 3222, a light shielding plate 3223, a beam splitter 3224, and a CCD line sensor 3232. That is, in this embodiment mode, the first light receiving system 3220 and the second light receiving system 3230 share the condenser lens 3221, the imaging lens 3222, the light shielding plate 3223, and the beam splitter 3224. In the configuration described above, the first light receiving system 3220 detects defects on the surface of the substrate 10, and the second light receiving system 3230 detects defects inside the substrate 10.

  The condensing lens 3221 collects scattered light generated on the surface and inside of the substrate 10. At this time, the light shielding plate 3223 blocks the inspection light (direct light) transmitted through the substrate 10 in front of the condenser lens 3221 so that it does not enter the condenser lens 3221. The imaging lens 3222 forms an image of the scattered light from the surface and the inside of the substrate 10 collected by the condenser lens 3221 at the position of the light receiving surface of the one-dimensional CCD image sensor 3225 or 3232. The beam splitter 3224 divides the light incident through the imaging lens 3222 into two, and emits the divided light in different directions. That is, one of the divided lights is emitted to the one-dimensional CCD image sensor 3225 side, and the other is emitted to the one-dimensional CCD image sensor 3232 side.

  The CCD image sensor 3225 of the first light receiving system 3220 receives one of the lights divided by the beam splitter 3224 and outputs a detection signal corresponding to the intensity of the received scattered light to the signal processing unit 220. . Here, the CCD image sensor 3225 is disposed at a position where the light receiving surface is an image surface of an optical system configured by the condenser lens 3221 and the imaging lens 3222 with respect to the surface of the substrate 10. That is, the first light receiving system is focused on the surface of the substrate 1.

  On the other hand, the one-dimensional CCD image sensor 3232 of the second light receiving system 3230 receives the other light among the lights divided by the beam splitter 3224, and outputs a detection signal corresponding to the intensity of the received scattered light to a signal conversion circuit. Output to 50. Here, the CCD image sensor 3232 is configured such that the distance from the beam splitter 3224 is different from that of the CCD image sensor 3225. That is, the light receiving surface of the CCD image sensor 3232 is arranged not to be the surface of the substrate 10 but to be an image surface with respect to a surface having a predetermined depth inside the substrate 10. That is, the second light receiving system is focused inside the substrate 1. As a result, not only surface defects but also internal defects can be inspected.

Next, a procedure for inspecting the substrate 10 with the optical inspection apparatus 140 having the above-described configuration will be described with reference to FIG.
First, the stage 250 (corresponding to the first transfer stage 120 in FIG. 1) held by the chucks 251 and 252 with the substrate 10 in the air floating state is driven by a table driving means (not shown) to optically. It moves to the position of the type | formula inspection apparatus 140 (S301). Next, at the position of the defect detection system 140, the stage 250 moves at a constant speed in the X direction along the linear guide 255 by the ball screw 254 that is rotationally driven by the motor 253 controlled by the stage controller 230 (S302). .

  While moving the stage 250 at a constant speed in the X direction, light is emitted from the LED light source 301 of the crater detection optical unit 300 to the back surface of the substrate 10 and is collected by the condenser lens 311 out of the light transmitted through the substrate 10. The light transmitted through the focusing lens 312 and converged is detected by the detector 313 (S303). The signal detected by the detector 313 is sent to the signal processing unit 220 for processing, and the substrate 10 is detected from the concave shape of the surface of the substrate 10 due to the change in the thickness of the substrate 10 or the change in the amount of light received by the detector 304 due to the convex shape. A crater defect is detected (S304).

  When the stage 250 is further moved in the X direction at a constant speed, the glass substrate 10 reaches the position of the flaw defect detection optical unit 320, and the rear surface of the glass substrate 10 is irradiated with light by the light projecting unit 3210. Direct light out of the light irradiated by the light projecting unit 3210 and transmitted through the glass substrate 10 is blocked by the light blocking plate 3223. When the surface of the glass substrate 10 has scratches, dust, or defects such as bubbles or foreign matter in the substrate, scattered light is generated by the light irradiated by the light projecting unit 3210. This scattered light is also generated in a direction different from the direct light from the light projecting unit 3210 shielded by the light shielding plate 3223, and a part of the scattered light is collected by the condenser lens 3221.

  A part of the scattered light from the glass substrate 10 collected by the condenser lens 3221 passes through the imaging lens 3222 and enters the beam splitter 3224 to reach the CCD image sensor 3225 forming the first light receiving system. (S305). The remaining portion of the scattered light from the glass substrate 10 passes through the imaging lens 3222 and enters the beam splitter 3224 to reach the CCD image sensor 3232 that forms the second light receiving system (S305). Here, as described above, the position of the CCD image sensor 3225 is adjusted so that the light receiving surface of the CCD image sensor 3225 coincides with the imaging surface on which the image of the surface of the glass substrate 10 is formed by the imaging lens 3222. ing. On the other hand, the position of the CCD image sensor 3232 is adjusted so that the light receiving surface of the CCD image sensor 3225 coincides with the imaging surface on which an image inside the glass substrate 10 is formed by the imaging lens 3222.

  A signal in which an image of scattered light from the surface of the glass substrate 10 is detected by the CCD image sensor 3225 and a signal in which an image of scattered light from the inside of the glass substrate 10 is detected by the CCD image sensor 3232 are sent to the signal processing unit 220. In step S306, a defect from the surface of the substrate or a foreign matter defect is detected based on a signal from the CCD image sensor 3225. On the other hand, air bubbles and foreign matter defects inside the substrate are detected by a signal from the CCD image sensor 3232.

  Since the positions of the crater detection optical unit 300 and the flaw defect detection optical unit 320 are fixed and the distance between them is constant, the crater detection optical unit is obtained using the position information of the stage 250 obtained from the stage controller 230. The glass substrate is merged by merging the information on the crater defect of the substrate 10 detected at 300 and the information on the flaw defect or foreign substance defect on the substrate surface detected by the flaw defect detection optical unit 320 and the bubble or foreign substance defect inside the substrate. Ten defects are detected (S307).

  When the glass substrate 10 is moved in the X direction and the inspection area on the glass substrate 10 deviates from the detection visual field of the flaw defect detection optical unit 320, the stage controller 230 stops driving the X direction drive motor 253, and the glass substrate. It is checked whether the ten divided predetermined areas have been fully inspected (S308). When the inspection of the entire surface of the predetermined area is not completed, a Y-direction drive motor (not shown) is driven to shift the Y-direction position of the glass substrate 10 by one field of view detected by the scratch defect detection optical unit 320 (S309). .

  In this state, the stage controller 230 drives the X-direction drive motor 253 in the reverse direction to drive the glass substrate 10 at a constant speed in the −X direction, and the flaw defect detection optical unit 320 and the crater detection optical unit 300 Inspect the region of the glass substrate 10 that is shifted by one field of view (S302 to S307: However, when the inspection is performed while moving the glass substrate 10 in the -X direction, S305 to S307 are performed before S303 to S304. Run). By repeating this scanning, the crater detection optical unit 300 and the flaw defect detection optical unit 320 inspect a predetermined area of the glass substrate 10. When the inspection of the entire predetermined area is completed, the glass substrate 10 is transported to the position of the next optical inspection apparatus 141 (S310).

Here, examples of various defects detected by the signal processing unit 220 are shown in FIGS. 4A to 4D.
FIG. 4A shows an example of a flaw defect 401. The image of the flaw defect 401 is projected onto the pixel 400 of the CCD image sensor 3225 of the first light receiving system 3220 of the flaw defect detection optical unit 320, and a detection signal waveform like 402 is obtained. In the signal processing unit 220, the detection signal waveform 402 is processed, and the CCD pixel continuity (length L in FIG. 4A) and the length flatness ratio (L / W) when the glass substrate 10 is scanned in the X direction. ) To determine the flaw defect. A signal level 403 indicated by a bold line indicates a zero level of an output of each pixel of the CCD image sensor.

FIG. 4B shows an example of the foreign object defect 410. The foreign object defect 410 is projected onto the pixel 400 of the CCD image sensor 3225 of the first light receiving system 3220 of the scratch defect detection optical unit 320, and a detection signal waveform like 411 is obtained. The signal processing unit 220, and processes the detection signal waveform 411, the signal bottom peak level S of (minimum value level in Fig. 4B) is greater than the signal S _L of the lowest level of defect detection (defect detection threshold level) It determines what smaller than the signal level S _H determines flaw defect 401 as defective foreign matter.

  FIG. 4C shows an example of the dirt defect 420. The stain defect 420 is projected onto the pixel 400 of the CCD image sensor 3225 of the first light receiving system 3220 of the scratch defect detection optical unit 320, and a detection signal waveform like 421 is obtained. In the signal processing unit 220, the detection signal waveform 421 is processed, and the region corresponding to L × W on the image of the glass substrate 10 obtained by scanning the glass substrate 10 with the CCD image sensor 3225 exceeds a certain area. The occupied one is regarded as a stain defect.

An example of a crater defect 430 is shown in FIG. 4D. The crater defect 430 is a defect detected by the crater detection optical unit 300. The crater defect 430 is a part where the film thickness is thinner (thicker) compared to other parts, and the optical path of light transmitted through the inclined surface where the thickness of the glass substrate 10 changes at the peripheral part of the crater defect 430. In order to change with respect to the optical path of the light transmitted through the glass substrate having no change in thickness, the light passing through the defect is dimmed, for example, a long region of the pixel 400 of the CCD image sensor 3225, such as a waveform 431. signal is detected over L _2. In general, the area is larger than that of the scratch defect 401, foreign object defect 410, dirt defect 420, etc., and a signal is output for a long time.

  FIG. 5 shows a flowchart of defect classification in which a signal detected by the flaw defect detection optical unit according to this embodiment is received and processed by the signal processing unit 220.

First, detection signals from the CCD image sensor 3225 of the first light receiving system 3220 and the CCD image sensor 3232 of the second light receiving system 3230 are input (S501), and the glass substrate 10 is continuously moved in the X direction. A dimension L corresponding to the length in the X direction of the portion of the signal level higher than the reference signal level L _H is extracted from the image obtained by imaging with the CCD image sensor 3225 or 3232. A determination is made as to the size of the set reference dimension of L (S502). As a result, when the dimension L is larger than the reference dimension, the process proceeds to the next step.

  In the next step, the dimension W corresponding to the width of the defect is extracted from the output signal waveform of the CCD image sensor 3225 or 3232, and the value of L / W is set in advance in comparison with the dimension L obtained previously. The size is compared with the set reference value (S503). As a result, when the value of L / W is larger than the preset reference value of L / W, it is determined as a flaw defect (S504).

  On the other hand, when the value of L / W is smaller than a preset reference value, the process proceeds to the next step, where L and W are multiplied to determine the area of the region including the defect, and this is set in advance. A comparison is made with the reference value of the area that has been placed (S505). As a result, if the value obtained by multiplying L and W is larger than the preset reference value of the area, it is determined as a stain defect (S506).

If the value obtained by multiplying L and W is smaller than a preset area reference value, or if it is determined in step S502 that L is not greater than the reference value, the next step is executed. willing, signal _{S L} of the bottom peak levels lowest level of S the defect detection of the detection signal (defect detection threshold level), compared with the signal level _{S H} determines flaw defect 401 (S507).

As a result, if the bottom peak level S of the detection signal is greater than the minimum level of the signal S _L defect detection, smaller than the signal level S _H determines flaw defect 401 judges as foreign matter defect (S508).

Results of the comparison in S507, when the bottom peak level S of the detection signal is less than the minimum level of the signal S _L of the defect detection, or it is determined to be greater than the signal level S _H determines flaw defect 401, then, bottom peak level S of the detection signal it is determined whether or not smaller than the signal S _L of the lowest level of the defect detection (S509), the bottom peak level S of the detection signal is smaller than the signal S _L of the lowest level of the defect detection Is determined as normal (S510). On the other hand, if the bottom peak level S of the detection signal is determined to be larger than the minimum level of the signal S _L of the defect detection, bottom peak level S of the detection signal than the signal level S _H determines flaw defect 401 Therefore, the defect does not correspond to any of the scratch defect, the dirt defect, and the foreign substance defect classified as described above, and is determined as another defect (S511).

  In the defect classification step described above, the detection signal from the CCD image sensor 3225 of the first light receiving system 3220 and the detection signal from the CCD image sensor 3232 of the second light receiving system 3230 have been described without being separated. By determining which sensor the output signal is the result of processing, it is determined whether the classified defect is a defect on the surface of the glass substrate or a defect in the glass substrate be able to.

  In this apparatus, the glass substrate 10 is classified into a grade corresponding to the defect by integrating and processing data detected by the two optical system units, that is, the crater detection optical unit 300 and the flaw detection optical unit 320. Is possible.

FIG. 6 shows an example of a processing flow for classifying glass substrates into grades corresponding to detected defects.
First, the presence / absence of a crater defect is determined based on information obtained by the crater detection optical unit 300 (S601). If it is determined that there is a crater defect, the substrate to be inspected is removed from the production line as an NG product. Next, in the case where it is not determined that there is a crater defect, the presence or absence of a point defect such as a foreign object is determined (S602).

  If it is determined that a point defect such as a foreign substance exists above the reference, the inspection target substrate is removed from the production line as an NG product. Those that pass the determination of a point defect such as a foreign object are then transferred to a determination of a contamination defect (S603). A substrate that is determined to have a contamination defect having a size of a reference abnormality is removed from the production line as an NG product.

  Finally, determination of a flaw defect is performed (S604), and it is determined that there is no flaw defect exceeding the standard and all defect determinations are cleared, and the result is A-OK. Also, B-OK is determined if there is a scratch defect exceeding the standard.

  When the crater detection optical unit 300 and the flaw defect detection optical unit 320 perform detection while moving the glass substrate 10 in the −X direction, the detection signal of S601 is delayed from the detection signals of S602 to S604 to the signal processing unit 220. Entered. In this case, the detection signal from the flaw defect detection optical unit 320 is stored in the memory inside the signal processing unit 220, and the detection signal from the crater detection optical unit 300 at the corresponding location on the glass substrate is input. Thus, the determination process of S602 to S604 is performed.

  Here, the criteria (size, strength, front and back, etc.) for determining foreign matter defects and scratch defects and making OK or NG can be changed, and grade classification (excellent, good, acceptable, etc.) is also possible.

  In addition, depending on the use of the substrate and the substrate production method, the defect to be avoided may be brought to the top of the identification.

  According to the present embodiment, the crater defects detected by the crater detection optical unit 300 and the position coordinates of defects such as scratches and foreign matter detected by the scratch defect detection optical unit 320 are matched,

  DESCRIPTION OF SYMBOLS 10 ... Glass substrate 100 ... Glass substrate defect inspection system 120,130,150,160,250 ... Conveyance stage 140-143 ... Optical inspection apparatus 200 ... Defect detection part 210 ... Light source control unit 220 ... Signal processing part 230 ... Stage control Unit 240 ... CPU 300 ... Crater detection optical unit 301 ... LED light source 320 ... Scratch defect detection optical unit 3210 ... Projection unit 3220 ... First light reception system 3230 ... Second light reception system

Claims (9)

A first defect detection optical system for detecting light transmitted through the glass substrate; a second defect detection optical system for detecting scattered light generated on the surface or inside of the glass substrate by the light transmitted through the glass substrate; A glass substrate inspection apparatus comprising signal processing means for processing a signal detected by the first detection optical system and a signal detected by the second detection optical system,
The first defect detection optical system transmits first illumination light irradiation means for irradiating illumination light to the back surface of the glass substrate, and the glass substrate irradiated with illumination light by the first illumination light irradiation means. And first detecting optical system means for detecting the image of the surface of the glass substrate by condensing the focused light to form an image,
The second defect detection optical system includes a second illuminating light irradiating unit that irradiates the back surface of the glass substrate with an illuminating light from an oblique direction, and the glass irradiated with the illuminating light by the second illuminating light irradiating unit. A second detection optical system means for collecting and imaging the scattered light generated from the substrate to detect an image of the surface of the glass substrate;
The signal processing means detects a defect caused by a local thickness change of the glass substrate by inputting and processing a detection signal from the first detection optical system means, and the second detection A glass substrate defect inspection apparatus for detecting defects in the glass substrate by inputting and processing a detection signal from an optical system means.   The first detection optical system means of the first defect detection optical system is an image of the surface of the glass substrate by the light irradiated by the first illumination light irradiation means, transmitted through the glass substrate and condensed. The glass substrate defect inspection apparatus according to claim 1, wherein an image is formed on the first image sensor and detected by the first image sensor.   The second detection optical system means of the second defect detection optical system includes a condensing lens that collects light transmitted through the glass substrate irradiated with illumination light by the first illumination light irradiation means, An imaging lens that forms an image of the light collected by the condenser lens, an optical path branching unit that splits the optical path of the light that has passed through the imaging lens, and one of the branches branched by the optical path branching unit A second image sensor disposed at an image formation position of an image on the surface of the glass substrate by light, and a second image sensor disposed at an image formation position of an image inside the glass substrate by the other light branched by the optical path branching means. 3. The glass substrate defect inspection apparatus according to claim 1, further comprising: 1st light which permeate | transmitted the glass substrate with the 1st defect detection optical system was detected, and it generate | occur | produced on the surface or inside of the said glass substrate with the 2nd light which permeate | transmitted the said glass substrate with the 2nd defect detection optical system A glass substrate inspection method for detecting scattered light and processing the signal detected by the first detection optical system and the signal detected by the second detection optical system to inspect the glass substrate,
Detecting the first light transmitted through the glass substrate with the first defect detection optical system, irradiating the back surface of the glass substrate with the first illumination light, and irradiating the first illumination light Performing by detecting the image of the surface of the glass substrate by collecting and imaging the light transmitted through the glass substrate,
The second illumination light is detected on the back surface of the glass substrate by detecting scattered light generated on the surface or inside of the glass substrate by the second light transmitted through the glass substrate by the second defect detection optical system. Irradiated from an oblique direction, and the scattered light generated from the glass substrate irradiated with the second illumination light is condensed and imaged to detect an image of the surface of the glass substrate,
Processing the signal detected by the first detection optical system and the signal detected by the second detection optical system to inspect the glass substrate, and detecting the detection signal from the first detection optical system means Defects due to local thickness changes of the glass substrate are detected by inputting and processing, and detection signals from the second detection optical system means are input and processed to detect defects of the glass substrate. A glass substrate defect inspection method, which is performed by detecting a defect.   Detecting an image of the surface of the glass substrate irradiated with the first illumination light, the glass by the condensed light out of the light irradiated with the first illumination light and transmitted through the glass substrate. 5. The glass substrate defect inspection method according to claim 4, wherein an image of the surface of the substrate is formed on a first image sensor and detected by the first image sensor.   The scattered light generated from the glass substrate irradiated with the second illumination light is condensed and imaged to detect an image of the surface of the glass substrate. The light transmitted through the glass substrate is collected by a condenser lens, the collected light is transmitted through the imaging lens, the optical path of the light transmitted through the imaging lens is branched into two, and the branched one An image of the surface of the glass substrate by the imaging lens of the light of the optical path is formed on a second image sensor and detected by the second image sensor, and the glass substrate by the other branched light is detected. The glass substrate defect inspection method according to claim 4, wherein an internal image is formed on a third image sensor and detected by the third image sensor. A transport line; glass substrate mounting means for mounting a glass substrate; transport means for transporting the glass substrate mounting means along the transport line; and glass substrate defect inspection means installed at a plurality of locations on the transport line. A glass substrate defect inspection system provided,
Glass substrate defect inspection means installed at a plurality of locations on the transfer line are installed to inspect different areas of the glass substrate,
Each of the glass substrate defect inspection means,
A first illumination unit that irradiates a glass substrate with first illumination light, and a first detection optical system unit that detects light transmitted through the glass substrate illuminated by the first illumination unit. A defect detection optical unit of
A second illumination unit that irradiates the glass substrate with second illumination light; and a second detection optical system unit that detects light transmitted through the glass substrate illuminated by the second illumination unit. Two defect detection optical units;
A signal detected by the first detection optical system is processed to detect a defect due to a local thickness change of the glass substrate, and a signal detected by the second detection optical system unit is processed; A glass substrate defect inspection system comprising: a signal processing unit for detecting defects on the surface and inside of the glass substrate.   The first detection optical system unit of the first defect detection optical unit generates a first image of the surface of the glass substrate by the light irradiated by the first illumination unit, transmitted through the glass substrate, and condensed. The glass substrate defect inspection system according to claim 7, wherein an image is formed on one image sensor and detected by the first image sensor.   The second detection optical system unit of the second defect detection optical unit includes a condensing lens that collects scattered light generated from the glass substrate irradiated with illumination light by the second illumination unit, and the collection lens. An imaging lens that forms an image of the light collected by the optical lens, an optical path branching part that splits the optical path of the light that has passed through the imaging lens, and one of the lights branched by the optical path branching part And a second image sensor arranged at the imaging position of the image on the surface of the glass substrate and a third image sensor arranged at the imaging position of the image inside the glass substrate by the other light branched by the optical path branching portion. The glass substrate defect inspection system according to claim 7, further comprising:

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