JP5353564B2 - Determination condition setting method and defect inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for setting determination conditions in a defect inspection device capable of automatically setting and determination size, without having to perform resetting work of the determination size, and to provide the defect inspection device. <P>SOLUTION: The method for setting the determination condition for detecting the defect of a color filter which is used for a flat panel display device includes a step of photographing image of a determination size control pattern disposed in a color filter substrate by an imaging unit; a step of binarizing the photographed determination size control pattern; and a step of setting the determination size by an approximation line by a scatter chart, between the real size of the determination size control pattern and the pixel number of the binarized control pattern in the imaging section. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a determination condition setting method for a defect detection device used when detecting defects in a color filter used in a flat panel display device or the like, and a defect inspection device.

  FIG. 1 is a cross-sectional view showing an example of a color filter used in a color liquid crystal display device. The color filter 1 includes a black matrix (hereinafter referred to as BM) 3, a red R coloring pattern (hereinafter referred to as R pixel) 4-1, a green G coloring pattern (hereinafter referred to as G pixel) 4-2, blue on a glass substrate 2. B coloring pattern (hereinafter referred to as B pixel) 4-3, transparent electrode 5, photo spacer (hereinafter referred to as PS) 6, and vertical alignment (hereinafter referred to as VA) 7 were sequentially formed. Is.

  As a method for manufacturing a color filter having the above structure, a photolithography method, a printing method, and an ink jet method are known. FIG. 2 is a flowchart showing steps of a commonly used photolithography method. In the color filter, first, a step of forming BM on the glass substrate (C-1), a step of cleaning the glass substrate (C-2), and a step of applying and pre-drying a colored photoresist (C-3) ), A pre-baking step (C-4) for drying and curing the colored photoresist, a step (C-5) for exposing, a step (C-6) for developing, and a step (C-) for curing the colored photoresist. 7) The process of forming a transparent electrode (C-8) and the process of forming PS and VA (C-9) are performed in this order.

  For example, when pixels are formed in the order of R pixel, G pixel, and B pixel, from the step (C-2) of cleaning the color filter glass substrate to the step of curing the colored photoresist (C- In 7), the color resist is changed in the order of red R, green G, and blue B, and the process is repeated three times to form R, G, and B pixels.

  The BM 3 is formed on the glass substrate 2 by, for example, forming a metal thin film on the glass substrate 2, applying a photoresist to the metal thin film, and then exposing, developing, and developing a pattern having a BM shape by a photolithography method. A method of forming by etching, or a black photoresist resin is applied on the glass substrate 2, and a pattern having a BM shape is exposed and developed by a photolithographic method to develop a so-called resin. A method of forming a pattern called BM is used.

  In the step (C-3) of applying and pre-drying the colored photoresist, the colored photoresist is applied by a coating method such as a spin coating method or a die coating method. In the coating processing step, 5 μmΦ is applied on the color filter substrate. From 500 μmΦ to defects such as voids and missing shapes called foreign matters, and residual shapes may occur, and the voids and foreign matter defects may also occur in other processes. Those defects are detected using an automatic defect inspection apparatus, and the outflow of defective substrates is prevented.

In general, an automatic defect inspection apparatus includes a plurality of CCD line sensor cameras and light sources (LEDs) that can fully scan the inspection range of a color filter substrate while conveying the color filter substrate by a substrate conveyance unit (conveyor conveyance or air floating conveyance). An optical system using a halogen lamp, a xenon lamp, etc.) is configured, the color filter substrate surface is imaged, and the image captured by the image processing unit is processed to detect defects. An example of a captured image and a defect is shown in FIG. The BM3, R pixel 4-1, G pixel 4-2, and B pixel 4-3 of the color filter use a repetitive pattern to detect a defect 9 based on the lattice spacing (cell pitch). The repeated pattern is compared with the density difference, binarized with the set threshold value, and a defective portion is extracted. The extracted defect 9 is saved as a file and a database (hereinafter referred to as DB) by the defect data (defect coordinates and the number of pixels in the color filter substrate) from a computer including a personal computer.

  The detected defect size is used as a criterion for determining the defect quality. This defect size is obtained by converting the actual defect size into the number of pixels of the CCD line sensor camera (hereinafter, the number of pixels: unit PIX) in which the defect portion is imaged. If it exceeds the set numerical value, it is regarded as a defective defect (hereinafter, this set value is referred to as a determination size). FIG. 4A shows the imaged defect 10a. FIG. 4B shows an example of the pixel 10b of the CCD line sensor camera of the binarized defect portion. In the case of FIG. 4B, the number of pixels of the CCD line sensor camera is 49 pixels, that is, 7 pixels in both the X direction and the Y direction, and the defective pixel 10b has 11 PIX. When 11PIX exceeds the determination size, it is detected as a defect.

  This determination size is handled as one item of a file (hereinafter referred to as a recipe) in which inspection conditions for each product model (hereinafter referred to as a product type) are recorded, and is set by an operation manager.

JP 2009-41930 A

  The determination size is converted into the number of pixels on the basis of the actual size defect standard (μm unit) determined by the customer's defect standard or in-house internal standard, and is converted into a conversion table.

  The determination size conversion table is obtained and determined by an operation called “conditioning”. In this condition setting, a substrate on which a defect sample of about 10 μm to 100 μmΦ is formed is created and tabulated by repeatedly detecting detection size data. The time required for the table formation is about 5 to 10 days depending on the number of CCD cameras of the inspection apparatus.

  Normally, this conversion table does not change because it depends on the color filter substrate product model, but when a product with an extremely different product composition occurs (for example, when the type of colored photoresist is changed) ), Or if it is determined that the determination size for changing the resolution of the CCD line sensor camera of the inspection apparatus is to be greatly changed, the conversion table must be changed.

  In addition, when a displacement (for example, deterioration of the light source over time) occurs in the optical conditions of the inspection apparatus over time, the defect size that is determined to be defective may differ from the determination size at the time of setting. For this reason, it is necessary to manage so that a defect does not flow out using a sample substrate used for daily inspection, which is a heavy work burden for the operation manager of the inspection apparatus. Further, when it is necessary to reset the determination size, the conversion table must be changed.

  The resetting of the determination size causes a long-time production stop not only in the inspection process but also in the entire manufacturing process, and causes a reduction in the production amount of the factory.

In view of the above problems, the present invention provides a determination condition setting method and a defect inspection apparatus in a defect inspection apparatus capable of automatically setting a determination size without performing determination size resetting work. Is an issue.

  The invention according to claim 1 of the present invention is a determination condition setting method for detecting a defect of a color filter used in a flat panel display device, wherein a determination size adjustment pattern provided on a color filter substrate is captured by an imaging unit. Take the image, binarize the imaged judgment size adjustment pattern, and determine the judgment size from the approximate line by the scatter diagram between the actual size of the judgment size adjustment pattern and the number of pixels of the imaging part of the binarized adjustment pattern This is a determination condition setting method characterized by performing the above setting.

  The invention according to claim 2 of the present invention is characterized in that the judgment size adjustment pattern is a pattern having a shape omission and a shape remaining, and has a plurality of patterns each having a different size. This is a determination condition setting method.

  According to a third aspect of the present invention, a determination size adjustment pattern is provided on an exposure photomask for transfer to a color filter substrate, and the transferred determination size adjustment pattern is scanned by each imaging camera of the imaging unit. 3. The determination condition setting method according to claim 1, wherein at least one is provided for each area. 4.

  In the invention according to claim 4 of the present invention, an approximate straight line between the actual size of the determination size adjustment pattern and the number of pixels of the imaging unit of the binarized adjustment pattern is acquired for each imaging camera, and for each imaging camera. The determination condition setting method according to claim 1, wherein a determination size is set in the method.

  The invention according to claim 5 of the present invention is a defect detection apparatus characterized by performing defect detection using the determination condition setting method according to any one of claims 1 to 4.

  When changing the colored photoresist, when changing the resolution of the CCD line sensor camera of the inspection device, or when the light source is deteriorated or replaced, it is judged that the judgment size will change greatly. Judgment size can be set in a short time, and as a result, it is possible to eliminate the labor of daily inspection by the operation manager of the inspection device and further eliminate the need for adjustment work that originally uses long days. It is possible to prevent a decrease in production without stopping the manufacturing process for a long time.

The figure which showed an example of the color filter used for a color liquid crystal display device in a cross section. The flowchart of the process of the photolithographic method generally used. The figure which shows an example of a captured image and a defect. (a) is a figure which shows the imaged defect. FIG. 4B is a diagram illustrating pixels of a binarized defect CCD line sensor camera. The figure which shows schematic structure of an example of the defect inspection apparatus which concerns on this invention. The figure which shows an example of the determination size adjustment pattern used for the determination condition setting in the defect inspection apparatus which concerns on this invention. The actual pattern size (μm ² ) on the X axis and the pattern detection size on the Y axis in the number of pixels (unit PIX) for the defect acquired by the determination size adjustment pattern used for setting the determination condition in the defect inspection apparatus according to the present invention. A scatter diagram.

  A mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 5 is a diagram showing a schematic configuration of an example of the defect inspection apparatus according to the present invention. The defect inspection apparatus images the transport unit 23 for transporting the color filter substrate 20 in the direction of the arrow 25, the reflection light source unit 21a and the transmission light source unit 21b that illuminate the color filter substrate 20, and the illuminated color filter substrate 20. An imaging unit 22 and a control unit 24 are included. The reflection light source unit 21a, the transmission light source unit 21b, the imaging unit 22, and the transport unit 23 are connected to the control unit 24 and controlled.

  The reflection light source unit 21a and the transmission light source unit 21b are installed so as to perform uniform illumination over the entire width in the direction orthogonal to the conveyance direction of the color filter substrate 20, and a halogen light source, for example, is used. In the imaging unit 22, a plurality of CCD line sensor cameras are arranged with respect to the full width in the direction orthogonal to the conveyance direction of the color filter substrate 20. The CCD line sensor camera used here may be for monochrome, and the captured image data is converted into, for example, 256 gradation digital data by an image data processing unit (not shown). The image data converted into digital data is binarized with a preset threshold value. In this case, analog image data captured without being converted into 256-gradation digital data may be binarized with a certain threshold value. The transport unit 23 may transport the color filter substrate 20 using, for example, a transport roller 26, a conveyor transport, or an air levitation transport, or a stage is provided for transport and the color filter substrate 20 is placed on the stage. The stage may be moved and conveyed. Furthermore, the reflection light source unit 21a, the transmission light source unit 21b, and the imaging unit 22 may be driven and moved while the color filter substrate 20 is mounted on a stationary mounting table.

  FIG. 6 is a diagram showing an example of a determination size adjustment pattern used for determination condition setting in the defect inspection apparatus according to the present invention. In the manufacturing process of the color filter substrate, the exposure process when forming each color pixel of BM, RGB, each pattern of ITO, PSVA is performed using an exposure photomask for exposing the pattern. On the exposure photomask, as shown in FIG. 6, 10 levels of defect judgment size adjustment patterns called “shape missing” and “shape remaining” of 10 μmΦ to 100 μmΦ are formed at intervals of 10 μmΦ. At least one determination size adjustment pattern of FIG. 6 is provided in the scanning area of all the CCD line sensor cameras of the defect inspection apparatus.

  The determination size adjustment pattern is 10 μmΦ to 100 μmΦ, and 10 levels are formed at intervals of 10 μmΦ. However, this is an example, and the present invention is not limited to this.

FIG. 7 shows a scatter diagram in which the actual pattern size (μm ² ) is represented on the X axis and the pattern detection size is represented by the number of pixels (unit PIX) on the Y axis with respect to the acquired defect. From the obtained scatter diagram, calculation of an approximate line, that is, an approximate line by the least square method: Y = aX + b is derived. As a result, the Y value that is the detected size (PIX) at that time is derived with respect to the X value that is the actual pattern size.

In FIG. 7, for example, when it is desired to determine a defect having an actual size of 2500 μm ² or more (corresponding to a size of 50 μm * 50 μm) as a defective defect, approximately 70 PIX is set as the determination size.

  In the defect inspection apparatus, the determination size adjustment pattern 30 and the impositioned color filter 31 pattern are imaged. The image captured by the CCD line sensor camera is subjected to density comparison / difference processing on the left / right / up / down repetitive patterns based on the lattice spacing (cell pitch), binarized with the set threshold value, and the defect portion is extracted, and the defect of all patterns Get the size.

  Based on the obtained determination size, the defect determination of all the acquired patterns is performed.

  Note that the scatter diagram shown in FIG. 7 is acquired for each CCD line sensor camera due to differences in sensitivity characteristics among the cameras of the plurality of CCD line sensor cameras and differences in illumination conditions between the reflected light source unit 21a and the transmitted light source unit 21b. It is desirable to set a determination size for each CCD line sensor camera.

  As an embodiment of the present invention, a CCD line sensor camera is exemplified as the imaging camera used in the imaging unit, but the present invention is not limited to this, and a two-dimensional CCD camera may be used.

  The present invention transfers a determination size adjustment pattern provided on an exposure photomask to a substrate, converts the actual size of the transferred defect into the number of pixels of a CCD line sensor camera, and performs defect determination from a captured image. Since the determination size is set when performing, it is not limited to color filters used in flat panel display devices such as liquid crystal display devices and plasma display devices, and can be widely used in substrate inspection devices.

  As described above, according to the determination condition setting method and the defect inspection apparatus according to the present invention, the determination size can be automatically set, and as a result, the inspection apparatus can be used without using the sample substrate used for daily inspection. This eliminates the need for daily inspection by the operation manager of the system, and further eliminates the need for adjustment work that would normally use a long period of time, thus preventing the production process from being stopped for a long time and preventing a decrease in production volume. Is possible.

DESCRIPTION OF SYMBOLS 1 ... Color filter 2 ... Glass substrate 3 ... Black matrix (BM)
4-1 ... Red R colored pixels (R pixels)
4-2 ... Green G coloring pixel (G pixel)
4-3 ... Blue B colored pixels (B pixels)
5 ... Transparent electrode 6 ... Photospacer (PS)
7 ... Vertical alignment (VA)
9 ... Defect 10a ... Imaged defect 10b ... Pixel 20 of the CCD line sensor camera of the binarized defect part ... Color filter substrate 21a ... Reflection light source part 21b ... Transmission Light source unit 22 ... Imaging unit 23 ... Conveying unit 24 ... Control unit 25 ... Arrow 26 indicating conveying direction ... Conveying roller 30 ... Determination size adjustment pattern 31 ... Imposition Color filter

Claims (5)

  A determination condition setting method for detecting defects in a color filter used in a flat panel display device, wherein a determination size adjustment pattern provided on a color filter substrate is imaged by an imaging unit, and the captured determination size adjustment pattern is Judgment condition characterized in that the judgment size is set from an approximate straight line by a scatter diagram between the binarized actual size of the judgment size adjustment pattern and the number of pixels of the imaging unit of the binarized adjustment pattern Setting method.   The determination condition setting method according to claim 1, wherein the determination size adjustment pattern is a pattern having a shape indicating a missing shape and a remaining shape, and has a plurality of patterns each having a different size.   Provided on an exposure photomask for transferring and providing a judgment size adjustment pattern to a color filter substrate, and provided so that at least one transferred judgment size adjustment pattern is included in each scanning area of each imaging camera of the imaging unit. The determination condition setting method according to claim 1, wherein the determination condition is set.   An approximate straight line between the actual size of the determination size adjustment pattern and the number of pixels of the imaging unit of the binarized adjustment pattern is acquired for each imaging camera, and a determination size is set for each imaging camera. The determination condition setting method according to claim 1.   A defect detection apparatus that performs defect detection using the determination condition setting method according to claim 1.

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