JP4619748B2 - Defect detection method for multilayer flat plate inspection object having optical transparency - Google Patents

Description

  The present invention relates to a defect inspection method for identifying a layer containing defects such as scratches and foreign matter in a light-transmitting multilayer flat plate-shaped inspection object such as a liquid crystal substrate.

In the process of manufacturing a liquid crystal substrate or the like, defects such as scratches and foreign matter may occur, and it is necessary to detect and correct these defects.
Conventionally, in order to detect these defects, the inspection part of the liquid crystal substrate is irradiated with inspection light, and the image data obtained by photographing the scattered light from the defective part of the inspection part with a CCD camera or the like is subjected to image processing. Discloses a method for detecting a defect position in a plan view (Patent Document 1).
Also, an inspection method for detecting a defect position by irradiating light from the lower surface of the inspection site of the liquid crystal substrate, performing image processing on image data obtained by photographing a transmitted light from the defect of the inspection site with a CCD camera or the like (patent) Document 2) is disclosed.
Japanese Patent Laid-Open No. 10-038753 Japanese Patent Laid-Open No. 09-033448

However, there are cases where the defect exists on the surface of the inspected site (FIG. 2a) and in the layer of each layer in the inspected site (FIG. 2b). In the case of a defect, in the prior art (Patent Document 1), sufficient scattered light from this defect portion cannot be obtained, and detection is difficult.
Moreover, in the said prior art (patent document 2), although the defect position in planar view can be detected, the defect which exists in the surface of the said to-be-inspected site | part and the defect which exists in each layer cannot be distinguished. Therefore, it is necessary to check these defective portions using a microscope, and there is a problem that the working time is prolonged.

  Therefore, in order to cope with such problems, the present invention provides a method in which a layer in which an internal defect exists can be specified when detecting a defect of a multilayer flat plate inspection object having optical transparency. The issue is to provide.

In order to solve the above-described problems, the defect detection method for a light-transmitting multilayer flat-plate inspection object is to irradiate light on a measurement site of the light-transmitting multilayer flat inspection object. The imaging means provided facing the multi-layer plate-like object to be inspected is continuously approached in the direction perpendicular to each layer of the measurement site of the multilayer flat-plate object to be inspected by the imaging means . Distribution of data relating to the brightness in the perpendicular direction for each layer of the measured region based on the continuously captured image data after continuously capturing the image data in the perpendicular direction for each layer of the measured region Next, the distribution of data regarding the brightness in the perpendicular direction for each layer and the direct data for each layer in the portion corresponding to the measured portion of the defect-free multi-layer flat reference inspection object obtained in advance. By comparing the distribution of the data relating to the brightness of the direction, it is characterized by identifying the presence or absence of a defect in the measurement region of the multilayer flat-plate-shaped device under test.

According to the defect detection method for a multilayer flat plate inspection object having optical transparency according to the present invention, the distribution of data relating to the brightness in the perpendicular direction for each layer of the measurement target portion of the inspection object and the memory are stored in advance. By comparing the distribution of data relating to the brightness in the direction perpendicular to each layer at the corresponding part of the defect-free reference inspection object, the layer of the inspection object in which a defect exists can be specified.
That is, the distribution of the data regarding the brightness in the perpendicular direction for each layer of the portion where the defect exists in the measured region is different from the distribution of the data regarding the brightness in the perpendicular direction for each layer in the corresponding portion of the reference specimen. Therefore, there is an excellent effect that a layer in which a defect exists in the inspection object can be easily identified and detected.

  In order to efficiently and easily identify the layer in which a defect exists in a horizontally placed multi-layer flat specimen, the vertical direction of each layer is determined from the vertical image data of each layer at the measurement site of the specimen. An operation for obtaining a distribution of data relating to brightness and comparing it with a distribution of data relating to the brightness in the vertical direction of each layer obtained in advance for a defect-free multilayer flat-plate reference inspection object is performed.

Hereinafter, a method for detecting a defect of a multilayer flat plate inspection object having optical transparency as an embodiment of the present invention will be described with reference to the drawings.
First, a description will be given of an apparatus according to a defect detection method for a multilayer flat plate inspection object having optical transparency according to the first embodiment of the present invention. As shown in FIG. 1, the defect detection apparatus 1 is a flat inspection object. 2 and a moving means 13 that can move the gantry 3 in the X-axis direction and the Y-axis direction (direction perpendicular to the paper surface). An objective lens 4 provided, an imaging lens 5 provided coaxially with the objective lens 4, and an object to be inspected 2 provided with a light receiving surface at the imaging position of the imaging lens 5 An inspection light L is applied to a measurement site including a CCD camera 6 as an imaging means for capturing an image of the site, and an intersection 9 between the vertical optical axis 7 of the objective lens 4 and the object 2 to be inspected. And an optical system 11 including an illuminating means 8 capable of adjusting the amount of light.

  The defect detection apparatus 1 also includes a Z-axis direction moving means 10 that allows the optical system 11 to move integrally in the vertical direction of the object 2 to be inspected (Z-axis direction parallel to the optical axis 7), and the optical system 11. A position detector 12 for detecting the position in the Z-axis direction and a measuring device 14 for processing the image data of the measured region of the device under test 2 captured by the CCD camera 6 are provided.

  The measuring device 14 includes an A / D converter 15 that converts the analog image signal in the vertical direction of each layer of the inspection object 2 obtained by photographing with the CCD camera 6 into a digital signal, and the A / D converter. The image memory 16A for storing the digital signal from 15 and the digital signal captured in the image memory 16A are read out, and data relating to the brightness in the vertical direction of each layer is created from the digital signal, and the distribution of the data is determined. An arithmetic unit 17 to be obtained and a reference memory 16B in which a distribution of data relating to the brightness in the vertical direction of each layer of the reference inspection object is stored.

  Further, it is possible to display the distribution of data relating to the brightness in the vertical direction of each layer of the inspection object 2 from the computing unit 17 and the distribution of data relating to the brightness in the vertical direction of each layer of the reference inspection object extracted from the reference memory 16B. A display 18 is provided.

  The data relating to the brightness means data obtained by quantifying a luminance difference (contrast) between a bright part and a dark part existing in an image captured by the photographing unit (CCD camera 6). The distribution means a change state of data relating to the brightness in the moving direction (Z-axis direction in FIG. 1) of the photographing means (CCD camera 6) (see, for example, FIGS. 5a and 5b). The same applies to the following.

Next, with reference to FIGS. 1 to 7 for the defect detection method for the inspection object according to the first embodiment of the present invention, which is performed by the defect detection apparatus 1 together with the operation of the defect detection inspection apparatus 1 having the above-described configuration. To explain.
In the defect detection method of the first embodiment, as a preparatory step before performing the defect detection of the inspection object 2, the reference inspection object is set on the gantry 3 as shown in FIG. 13 is used to move the gantry 3 in the XY directions (step 2), light is irradiated by the illumination means 8 at each position, and the optical system 11 is continuously approached to the reference inspection object by the Z-axis direction moving means 10. However, the image is taken by the CCD camera 6, the vertical image data of each layer at each position is taken in (step 3), and the image data is converted into a digital signal by the A / D converter 15 and stored in the memory 16A ( Step 4), fetching the stored vertical image data of each layer into the computing unit 17 to obtain a distribution of data relating to the vertical brightness of each layer of the reference inspection object (Step 4). 5), and stores the result in the memory 16B (step 6).
After completion of the preparation process, the reference inspection object is removed from the gantry 3 and the stored contents of the memory 16A are deleted (reset) (step 7).

  In the distribution, since there is no foreign matter or the like in the reference inspection body, the contrast of the image captured by the CCD camera 6 is other than each surface to be imaged (for example, a surface on which the CCD camera 6 is focused, such as a boundary surface of each layer). The distribution of data regarding brightness is not as shown in FIG. 5a.

Next, in the inspection process in the defect detection method of the first embodiment, as shown in FIG. 4, the inspection object 2 whose defect position is clarified in plan view is placed on the gantry 3. (Step 10)
Then, the gantry 3 is moved in the XY directions using the gantry moving means 13 so that the defect position is directly below the optical axis 7 of the objective lens. (Step 11)
In this state, while the optical system 11 is continuously approached to the inspection object 2 by the Z-axis direction moving means 10, the measurement site of the inspection object 2 is imaged by the CCD camera 6. (Step 12)
Then, the image data of the measurement site of the object 2 to be inspected continuously taken in the vertical direction by the CCD camera 6 is converted into a digital signal by the A / D converter 15 and stored in the memory 16A. (Step 13)

Next, the digital signal stored in the memory 16A is taken into the computing unit 17, and data relating to the brightness in the vertical direction of each layer of the measurement site of the device under test 2 is created from the digital signal. A distribution of data relating to the brightness in the vertical direction of each layer of the part to be measured is obtained. (Step 14)
When the defect of the inspection object 2 is caused by a foreign substance, the CCD camera 6 is focused on the defective portion, so the data distribution regarding the brightness in the layer where the defect exists is, for example, as shown in FIG. 5a and 5b indicate the position of the optical system 11 detected by the Z-axis direction position detector 12 in the Z-axis direction.

  Next, the distribution of data regarding the brightness in the vertical direction of each layer of the measurement site of the device under test 2 obtained by the computing unit 17 and the device under test 2 of the standard test sample obtained in the preparation step. The distribution of data relating to the brightness in the vertical direction of each layer of the part corresponding to the part (FIG. 5a) is displayed on the display 18 (step 15).

  Furthermore, when the operator visually confirms the distribution of data regarding the brightness displayed on the display 18 and the difference from the distribution of data regarding the brightness in the vertical direction of each layer of the reference inspection object exceeds the reference Is determined that there is a defect in the layer of the measured region of the inspection object 2. (Step 16)

  In the first embodiment described above, the distribution of the data relating to the brightness obtained by the computing unit 17 is directly displayed on the display unit 18, but as shown in FIG. Distribution of data relating to the vertical brightness of each layer of 2 and data relating to the brightness in the vertical direction of each layer of the part corresponding to the measured part of the inspection object of the reference inspection object obtained in the preparation step May be compared by the comparison / determination unit 19 and the result may be displayed on the display unit 18.

In the second embodiment, the defect detection method for the inspected object 2 by the defect detection / inspection apparatus 1A having the configuration shown in FIG. 6 is performed by the steps shown in FIG. 7, but the steps from step 1 to step 5 are performed. Same as Example 1.
That is, in the second embodiment, the distribution of data relating to the brightness in the vertical direction of each layer of the measurement site of the device under test 2 obtained by the computing unit 17 (for example, FIG. 5b) and obtained in the preparation step. A data distribution (for example, FIG. 5 a) relating to the brightness in the vertical direction of each layer of the part corresponding to the part to be measured of the inspection object 2 of the reference inspection object is supplied to the comparison / determination unit 19. Then, the peak values of the data regarding the brightness in the vertical direction of both layers are compared (step 15 '), and the layer of the measurement site of the object 2 to be inspected having a different peak value is recognized as a layer having a defect. The position of the layer is displayed on the display 18. (Step 16)

  In the method using the defect detection / inspection apparatus 1A according to the second embodiment, the determination as to the presence / absence of a defect does not depend on the operator's visual observation, so that individual differences among workers are less likely to occur, and the determination can be performed quickly. An effect is obtained.

In the defect detection methods of the first and second embodiments described above, the optical system 11 having the objective lens 4 and the imaging lens 5 is used, but the lens of the CCD camera 6 is used instead of the coupling lens 5. Also good.
Further, the relative movement means in the XY-axis direction between the inspected object 2 and the optical system 11 is not limited to the above-described configuration, and the optical system 11 may be moved by fixing the gantry 3 of the inspected object 2.

It is explanatory drawing which shows schematic structure of the defect detection apparatus for enforcing the defect detection method of the to-be-inspected object which concerns on Example 1 of this invention. It is explanatory drawing which shows an example of the foreign material which exists on the surface of a to-be-inspected object. It is explanatory drawing which shows an example of the foreign material which exists in one layer of to-be-inspected object. It is explanatory drawing which shows the preparatory process of the defect detection method of the to-be-inspected object in the apparatus of FIG. It is explanatory drawing which shows the inspection process of the defect detection method of the to-be-inspected object in the apparatus of FIG. It is a graph showing an example of the distribution of the data regarding the brightness of the layer of a reference | standard test body. It is a graph showing an example of the distribution of the data regarding the brightness of the layer of a to-be-inspected object. It is a figure which shows schematic structure of the defect detection apparatus for enforcing the defect detection method of the to-be-inspected object which concerns on Example 2 of this invention. It is explanatory drawing which shows the inspection process of the defect detection method of the to-be-inspected object in the apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Defect detection apparatus 2 Inspection object 3 Base 4 Objective lens 5 Imaging lens 6 CCD camera 7 Optical axis of objective lens 8 Illumination means 9 Intersection point of optical axis of objective lens and inspection object 10 Z-axis direction of optical system Moving means 11 Optical system 12 Optical system Z-axis direction position detector 13 Base moving means 14 Measuring instrument 15 A / D converter 16A Memory 16B Memory 17 Calculator 18 Display 19 Comparison comparator

Claims (1)

Irradiate light to the measurement site of the multi-layer plate-shaped object to be inspected with light transmittance,
While continuously approach the imaging means provided in opposition to the multi-layer flat-plate-shaped device under test in a perpendicular direction for each layer of the target part of the multilayer flat-plate-shaped device under test, by the photographing means, the object After continuously capturing the image data in the perpendicular direction for each layer of the measurement site,
Based on the continuously captured image data, obtain a distribution of data on the brightness in the perpendicular direction for each layer of the measurement site,
Next, the distribution of the data regarding the brightness in the perpendicular direction for each layer and the data regarding the brightness in the perpendicular direction for each layer in the part corresponding to the measured part of the defect-free multilayer flat-plate reference inspection object obtained in advance. A defect detection method for a multilayer flat-plate inspecting object having light transmissivity, wherein the presence or absence of a defect in a measurement site of the multilayer flat-plate inspecting object is specified by comparing with a distribution of the above.

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