KR100953204B1 - Board quality inspection device and inspection method - Google Patents

Abstract

The present invention discloses a quality inspection apparatus for a substrate and a method for inspecting the same. The inspection device and the inspection method include a change in brightness of a light source, noise from a power source caused by instability of the light source or alternating current power, vibration generated during a transfer process of a substrate to be inspected, vibration of equipment or environment, etc. When noise is included in the shadow image information under the influence of the noise, the device is configured to inspect the surface quality of the substrate in the state where the noise is removed. Improved quality satisfaction.

Board, Light Source, Camera, Noise

Description

Quality inspection device and inspection method of substrate {Glass waviness inspection device and inspection method

The present invention relates to a quality inspection technology of a substrate, and more particularly, to prevent inspection errors due to noise (signals, noise, poor light source, vibration of the substrate, etc.) caused by external factors when the quality inspection of the substrate is performed. The present invention relates to a quality inspection apparatus for a substrate and a method for inspecting the same for increasing inspection accuracy on the surface of the substrate.

The thin film transistor liquid crystal display is largely composed of a lower substrate on which a thin film transistor is formed, an upper substrate on which a color filter is formed, and a liquid crystal injected between the lower substrate and the upper substrate.

In the case of the substrate for forming the thin film transistor and the color filter, if a phenomenon such as phenomena, stains, scratches, foreign matters, etc. is present on the surface of the substrate, the product may be inferior.

Thus, the substrate is placed in a process chamber and the overall quality inspection of the substrate is performed before a process using plasma such as deposition, etching or sputtering is performed.

However, conventionally, when inspecting the quality of the surface to the substrate, the surface of the substrate by the camera, including the noise due to external factors such as noise due to electrical signals, light source defects, vibration generated during the transfer of the substrate to be inspected Image information is distorted, and accordingly, conventionally, the quality inspection of the surface of the substrate is not precisely performed, such as an error of determining a substrate having a quality abnormality as normal or an error of determining a defect even if there is no abnormality in quality. There is this.

Therefore, the present invention has been made to improve the above-mentioned conventional problems, the object of which is to examine the noise included in the image information (change in brightness of the light source, power source noise due to instability or AC power of the light source, By configuring the device to inspect the surface quality of the substrate in the state of eliminating the vibration generated during the transfer of the substrate, the vibration of the equipment or the vibration of the environment, etc. It is to provide a quality inspection apparatus of the substrate and the inspection method thereof.

The quality inspection apparatus of the present invention for achieving the above object is, in the configuration of the inspection unit for checking the surface quality of the substrate supplied to the processing equipment through the transfer unit, the inspection unit; An illumination unit for irradiating a light source; A second mirror unit reflecting the light source irradiated by the illumination unit; A screen unit for projecting a shadow image of the surface of the substrate from the transmitted light source when the light source reflected through the second mirror unit passes through the surface of the substrate; An image processing unit for photographing a shadow image of the surface of the substrate projected on the screen unit; And selecting an image of a specific region from a shadow image captured by the image processor to table pixel values (brightness) of columns of horizontal / vertical lines, and to calculate adjacent pixel values from pixel values of the table columns. A quality inspection unit extracting an average value by a moving average method to remove noise included in an image image as an external factor, and inspecting a quality state of the surface of the substrate from the shadow image information from which the noise is removed; It is configured to include.

In addition, the inspection unit, the lighting unit for irradiating the light source; A first mirror unit configured to transmit a portion of the light source irradiated by the illumination unit and reflect a portion in a specific direction; A second mirror unit reflecting a part of the light source transmitted through the first mirror unit to transmit the substrate; A first light amount detecting unit detecting a light amount of the light source transmitted when the light source reflected through the second mirror unit passes through the substrate; A second light amount detector for detecting a light amount from a part of the light source reflected through the first mirror in a specific direction; And comparing the amounts of light detected by the first and second light quantity detection units to remove noise included by external factors (eg, power source noise generated by characteristics of the substrate or AC power), and in the state where the noise is removed. Quality inspection unit for inspecting the quality of the surface of the substrate; It is configured to include.

In addition, the lighting unit is composed of any one of a light source, an infrared light source, and an LED light source of the xenon lamp.

In addition, the second mirror portion is preferably provided at an angle within the range of 10 ° to 90 ° to determine the incident angle of the light source.

Further, at the tip of the lighting unit, a slit is set to set the irradiation range of the light source to set an inspection area for a specific portion of the substrate.

In addition, the front end of the slit constitutes a filter member for transmitting only a wavelength band of a specific band from a light source.

In addition, the image processing unit includes a line scan CCD camera.

In addition, the first mirror unit is composed of a half mirror.

In addition, the progress of the quality inspection method implemented by the quality inspection apparatus of the substrate, the first step of selecting an image of a specific region to be observed in the entire image of the shadow image taken; Noises included in the image by tabulating pixel values (brightness) of horizontal / vertical lines in the image of the selected specific region and extracting average values of adjacent pixel values from the table pixel values by a moving average method. A second step of reducing primarily; The image obtained by adding or averaging horizontal line columns A1, A2, A3, A4, A5, ..., An from the average value of the extracted pixels in a state where noise is reduced primarily by the moving average method from the second step. A third step of outputting a signal; A fourth step of inspecting a quality state of the surface of the substrate by determining whether the image signal output from the third step exceeds a preset threshold; It includes.

Further, in the third step, the output of the image signal according to the sum (or average) result is obtained by the following equation.

Here, Δt means a time (about 1 to 2 msec) to perform another line scan after one line scan is performed by the image processor, and n is a natural number.

Further, in the third step, confirmation of which region of the image signal contains the noise signal is performed when the frequency signal waveform is converted through an algorithm of a Fast Fourier Transform (FFT).

The present invention is noise is affected by the change in brightness of the light source, the power source noise caused by the instability of the light source or alternating current power, the vibration generated during the transfer process of the substrate to be inspected, the vibration of the equipment or the vibration of the environment. When included in the shadow image information, the device is configured to inspect the surface quality of the substrate in the state of removing the noise, thereby eliminating errors in the quality inspection due to noise, thereby improving the inspection accuracy, thereby improving the quality satisfaction of the product It is possible to obtain an effect.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram of a substrate quality inspection apparatus according to an embodiment of the present invention, Figure 2 is a front view of a state in which a slit is applied to the lighting unit in an embodiment of the present invention, Figure 3 is an embodiment of the present invention filter in the lighting unit 4 is a schematic view showing the flow of the light source when applying a slit to the front end of the lighting unit in an embodiment of the present invention.

1 to 4, the quality inspection apparatus for a substrate according to an embodiment of the present invention is an inspection unit for checking a surface quality state of a substrate 200 supplied to a process facility through a transfer unit 100. In the configuration, the inspection unit includes an illumination unit 10, the second mirror unit 20, the screen unit 30, the image processing unit 40, and the quality inspection unit 50.

The illumination unit 10 irradiates a light source, which is composed of any one of a light source of an xenon lamp, an infrared light source, and an LED light source.

In this case, as shown in FIG. 2, a slit 11 for guiding the light source irradiation to the second mirror unit 20 is configured at the front end of the lighting unit 10, and a light source is formed at the front end of the slit 11. In the filter member 12 is configured to transmit only the wavelength band of a specific band.

At this time, the filter member 12 is to use any one of an ultraviolet filter, an infrared filter, and a visible light filter.

The ultraviolet filter transmits only the wavelength of the ultraviolet band or transmits only the wavelengths of the remaining visible and infrared regions while preventing only the wavelength of the ultraviolet band, and the wavelength band is in the range of 214 nm to 396 nm.

The visible light filter transmits only a specific wavelength in the visible light region, or transmits only a wavelength after the specific wavelength while preventing only a specific wavelength, or transmits to a wavelength before the specific wavelength and does not transmit a wavelength after the specific wavelength. To prevent this, the wavelength band is in the range of 426nm to 750nm.

The infrared filter transmits only a specific wavelength in the infrared region, or transmits only a wavelength after the specific wavelength and not only transmits to a specific wavelength, or transmits to a wavelength before the specific wavelength and does not transmit the wavelength after the specific wavelength. The wavelength band is in the range of 760nm to 1000nm.

The second mirror unit 20 is configured to reflect the light source irradiated from the lighting unit 10 to the substrate 200, and installed at an angle within a range of 10 ° to 90 ° to determine the incident angle of the light source according to the reflection. Is done.

The screen unit 30 is configured to project a shadow image of the surface of the substrate from the transmitted light source when the light source reflected through the second mirror unit 20 passes through the surface of the substrate 200.

The image processor 40 photographs a shadow image of the surface of the substrate 200 projected onto the screen unit 30, which uses a line scan CCD camera.

The quality inspector 50 inspects the external image, that is, the brightness change of the light source, the instability of the light source, or the electrical signal of a specific band (for example, 40 to 80 Hz) in the shadow image photographed by the image processor 40. The substrate 200 may be removed from the shadow image information from which the noise is removed from the shadow image while being affected by vibration generated during the transfer process of the substrate 200, vibration of the equipment, or environment vibration. It is configured to check the quality of the surface.

That is, the quality inspection apparatus and the inspection method of the substrate according to an embodiment of the present invention, as shown in Figures 1 to 13 attached, first, a thin film to the transfer unit 100 having a constant velocity section, such as a roller or robot arm The substrate 200 is transferred or stopped to a process facility that uses a plasma such as a deposition, etching, and sputtering process for manufacturing a transistor liquid crystal display.

At this time, when irradiating the light source from the illumination unit 10 installed at a predetermined irradiation angle at the lower end of the transfer unit 100, the light source is a second mirror portion 20 is installed at an angle within the range of 10 ° ~ 90 ° After the incident angle of the light source is determined through the reflection, the light is transmitted to the opposite surface of the substrate 200 transferred by the transfer unit 100.

Then, the shadow image of the substrate 200 is projected onto the screen unit 30 by the light source passing through the substrate 200, and the projected shadow image is captured by the image processing unit 40 which is a line scan CCD camera. After it is transmitted to the quality inspection unit 50.

Herein, when the illumination unit 10 is irradiated with the light source, the light source is provided with the slit 11 at the tip of the illumination unit 10 as shown in FIGS. The second mirror unit 20 may be irradiated through the filter member 12, and the light source may transmit only a wavelength band of a specific band through the filter member 12.

That is, the filter unit 12 may be selectively coupled to the illumination unit 10 as an ultraviolet filter, a visible light filter, or an infrared filter. In this case, the filter member 40 may be a light source irradiated from the illumination unit 10. Only transmits the wavelength band of a specific band.

That is, when the ultraviolet filter is applied as the filter member 12 to the lighting unit 10, the ultraviolet filter is ultraviolet light in the wavelength range of 214nm to 396nm when the lighting unit 10 irradiates the light source to the substrate 200. It transmits only the wavelength of the band or transmits only the wavelengths of the remaining visible and infrared regions while preventing only the wavelength of the ultraviolet band.

Then, the transmitted light source of the specific band is reflected in the state where the angle of incidence is determined through the second mirror unit 20 and is transmitted only to the surface of the substrate 200 while being transmitted to the opposite surface, and thus the substrate 200 The shadow image appears more clearly on the screen 30 by the light source transmitted to the upper surface of the image, and the clear shadow image is captured more clearly by the image processing unit 40, that is, the line scan type CCD camera. It can be transmitted to the inspection unit 50.

In addition, when the visible light filter is applied as the filter member 12 to the illumination unit 10, the visible light filter is a wavelength in the range of 426nm to 750nm when the illumination unit 10 irradiates the light source to the substrate 200 To transmit only a specific wavelength in the visible light region, or to transmit only a wavelength after the specific wavelength, but not to transmit only a specific wavelength, or to transmit a wavelength before a specific wavelength and not to transmit a wavelength after the specific wavelength. do.

Then, the light source of the specific band transmitted as described above is transmitted only to the surface of the substrate 200 while being transmitted to the opposite side, and thus the screen unit 30 by the light source transmitted to the upper surface of the substrate 200. The shadow image appears more clearly, and the clear shadow image may be transmitted to the quality inspecting unit 50 after being captured more clearly by the image processor 40.

In addition, when the infrared filter is applied as the filter member 12 to the illumination unit 10, the infrared filter is a wavelength band in the range of 760nm to 1000nm when the illumination unit 10 irradiates the light source to the substrate 200. To transmit only a specific wavelength in the infrared region, or not to transmit only to a specific wavelength, and to transmit only a wavelength after the specific wavelength, or to transmit to a wavelength before a specific wavelength and not to transmit a wavelength after the specific wavelength.

The light source of the specific band transmitted as described above is transmitted to the opposite side while irradiating only the surface of the substrate 200, and thus is projected onto the screen unit 30 by the light source transmitted to the upper surface of the substrate 200. The shadow image appears more clearly, and the clear shadow image is captured by the image processor 40 more clearly and then transmitted to the quality controller 50.

In this case, the quality inspecting unit 50 waveforms the sharply captured shadow image as described above, and removes the noise included in the shadow image by external factors in the waveform image, while removing the noise By comparing the image information (image signal) with the boundary condition of the reference value for the flatness of the substrate which is a preset threshold value, it is possible to more accurately determine whether a defect has occurred on the surface of the substrate 200.

In more detail, first, the quality inspecting unit 50 first selects an image of a specific region to be observed from the entire image of the shadow image photographed and transmitted by the image processing unit 40 as shown in FIG. 5.

Here, selecting only the image of a specific area without selecting the entire image of the shadow image, when the quality inspection for the substrate 200 is performed, the shape of the shoulder is generally shown in the horizontal direction as shown in FIG. Since it may be oblique as shown in the drawing, when the entire image of the shadow image is selected, a problem may occur in summing (or averaging) only the area that is the signal, that is, the signal during the summing process.

Next, as shown in FIG. 6, the pixel values (brightness) for the columns of the horizontal / vertical lines in the image of the selected specific region are tabled, and the adjacent pixel values in the pixel values of the table columns are listed. When the average value is extracted by the moving average method, the noise included in the video image may be primarily reduced by the extracted average value.

Here, the noise is already included in the image of the shadow image in the process of accumulating data, the root cause of the noise is the brightness change of the light source, the instability of the light source or the electrical signal of a specific band, the substrate to be examined ( It is included in the shadow image under the influence of the vibration generated during the transfer process, the vibration of the equipment or the environment of the environment, etc. Accordingly, the quality inspection unit 50 is to first perform the task of reducing the noise first will be.

Next, in the state where the noise is primarily reduced by the moving average method as described above, the quality inspector 50 performs horizontal line columns A1, A2, and A3 as shown in FIG. 7 attached from the average value of the extracted pixels. An image signal obtained by summing (or averaging) A, A4, A5, ..., An is output. The image signal is obtained by the following equation.

Here, Δt means a time (about 1 to 2 msec) for another line scan after one line scan is performed by the image processor, and n represents a natural number.

In this case, the image signal is waveformd as shown in FIG. 8, and the noise included in the waveformd image signal is converted into a frequency signal waveform as shown in FIG. 9 through a fast Fourier transform (FFT) algorithm. When the examiner can see directly.

Accordingly, the quality inspector 50 determines whether the image signal including noise exceeds a predetermined threshold, which is a boundary condition of the reference value for the flatness of the substrate, and determines the threshold as the result of the determination. When exceeding, the quality inspection unit 50 is to check the quality of the surface of the substrate precisely as shown in FIG.

That is, the width of the shoulder to be detected is about 3 mm to 10 mm, the thickness is several or several tens of nm, and the substrate 200 performs constant velocity motion (v = constant), and image information is every specific time (1 to 2 msec). When the image signal of FIG. 8 is FFT-converted as shown in FIG. 9, the area of the 3mm interval is t (time) = 3mm / v, which is converted into a frequency. In this case, f = 1 / t = v / 3mm, and the desired signal area is f1 to f2 (f1: f1 = 1 / t = v / 3mm, f2 = 1 / t2 = v / 10mm).

Therefore, the area outside the above range is considered noise and is unnecessary. Accordingly, the quality inspector 50 detects the boundary condition of the reference value for the flatness of the substrate, which is a preset threshold, and the image signal of the inspection target substrate 200. In comparison, it is possible to check more precisely whether or not the surface of the substrate 200 is generated.

Here, when the waveform of the image signal of FIG. 10 from which noise is removed as described above is converted into a frequency signal waveform as shown in FIG. 11 through FFT conversion, the inspector can directly check a state in which noise is removed.

On the other hand, Figure 14 is another embodiment of the present invention with respect to the inspection unit, the illumination unit 10 for irradiating the light source, a portion of the light source irradiated by the illumination unit 10 transmits a portion of the first to reflect in a specific direction The mirror unit 60, the second mirror unit 20 reflecting some light sources transmitted through the first mirror unit 60 to transmit the substrate 200, and the second mirror unit 20 reflects the second mirror unit 20. When the light source is transmitted through the substrate 200, the light amount is detected from the first light amount detection unit 70 for detecting the light amount of the light source transmitted through the light source, and a part of the light source reflected in a specific direction through the first mirror unit 60 Compared with the amount of light detected by the second light amount detection unit 80 and the first and second light amount detection units 70 and 80, power generated from noise or AC power included by the characteristics of the substrate as an external factor. Removes noise and removes the substrate from the amount of light It is configured to include a quality inspection unit 50 to inspect the quality of the surface of the.

That is, according to another embodiment of the present invention, as shown in FIG. 14, when the light source is irradiated from the illumination unit 10, a part (50%) of the light source is composed of a half mirror 60. Is guided to the second light quantity detection unit 80, and another portion (50%) is transmitted to the second mirror unit 20 through the first mirror unit 60.

Then, the second light amount detecting unit 80 detects the light amount of the light source and outputs the light amount to the quality inspecting unit 50, and the second mirror unit 20 transmits the first mirror unit 60 to the quality inspecting unit 50. A portion of the light source transmitted through the light reflected through the substrate 200.

In this case, when the light source reflected through the second mirror unit 20 passes through the substrate 200, the light amount of the transmitted light source is detected by the first light amount detection unit 70 and then transmitted to the quality control unit 50. Output bar,

The quality control unit 50 compares the amount of light detected by the first and second light amount detecting units 70 and 80, removes noise (especially power supply noise) included by external factors, and removes the amount of light from which the noise is removed. From this, the quality of the surface of the substrate is inspected.

That is, the amount of light detected by the second light amount detector 80 is not affected by the substrate 200, and the amount of light detected by the first light amount detector 70 passes through the substrate 200. Will be affected by the substrate 200,

The quality inspecting unit 50 removes power supply noise generated by AC power from the amount of light detected by the first light amount detecting unit 70 based on the amount of light detected by the second light amount detecting unit 80 as a reference value. Accordingly, the quality inspector 50 compares the amount of light from which the noise is removed with a boundary condition of a reference value with respect to the flatness of the substrate, which is a preset threshold value, to determine whether the surface of the substrate 200 is generated. Will be able to check more precisely.

Hereinafter, the same parts as in the embodiment of the present invention will be denoted by the same reference numerals and description thereof will not be repeated.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. It is to be understood that such changes and modifications are within the scope of the claims.

1 is a block diagram of a quality inspection apparatus of a substrate according to an embodiment of the present invention.

2 is a front view of a state in which a slit is applied to the lighting unit in an embodiment of the present invention.

3 is a state in which the filter is mounted on the lighting unit in an embodiment of the present invention.

Figure 4 is a schematic diagram showing the flow of the light source when applying the slit to the tip of the lighting unit in an embodiment of the present invention.

5 to 11 is a flowchart illustrating a quality inspection method of a substrate according to an embodiment of the present invention.

12 and 13 are schematic diagrams showing horizontal scales or diagonal scales on the substrate surface according to the embodiment of the present invention.

14 is another embodiment of the present invention for the inspection unit.

* Description of the symbols for the main parts of the drawings *

10; Lighting unit 11; Slit

12; Filter member 13; Light path

20; Second mirror portion 30; Screen part

40; An image processor 50; Quality Inspection Department

60; First mirror portion 70, 80; First and second light quantity detector

100; Transfer unit 200; Board

Claims (18)

In constructing an inspection unit for checking the surface quality of the substrate supplied to the process equipment through the transfer unit, The inspection unit is; An illumination unit for irradiating a light source; A second mirror unit reflecting the light source irradiated by the illumination unit; A screen unit for projecting a shadow image of the surface of the substrate from the light source passing through the surface of the substrate when the light source reflected through the second mirror portion passes through the surface of the substrate; An image processing unit for photographing a shadow image of the surface of the substrate projected on the screen unit; And, By selecting an image of a specific region in the shadow image captured by the image processor, the pixel values (brightness) of the columns of the horizontal / vertical lines are tabled, and the average value of the adjacent pixel values is calculated from the pixel values of the table columns. A quality inspection unit extracting a moving average method to remove noise included in an image image as an external factor and inspecting a quality state of the surface of the substrate from the shadow image information from which the noise is removed; Quality inspection apparatus of the substrate, characterized in that comprising a. The apparatus of claim 1, wherein the illumination unit is any one of a light source, an infrared light source, and an LED light source of the xenon lamp. The apparatus of claim 1 or 2, wherein a slit for guiding the light source to be irradiated only to the second mirror is formed at the tip of the lighting unit. The apparatus of claim 1 or 2, wherein the second mirror unit is disposed at an angle within a range of 10 ° to 90 ° to determine an incident angle of the light source. 4. The apparatus of claim 3, wherein a filter member is formed at a tip of the slit to transmit only a wavelength band of a specific band from a light source. delete delete delete The apparatus of claim 1, wherein the image processor is a line scan CCD camera. In constructing an inspection unit for checking the surface quality of the substrate supplied to the process equipment through the transfer unit, The inspection unit, An illumination unit for irradiating a light source; A first mirror unit configured to transmit a portion of the light source irradiated by the illumination unit and reflect a portion in a specific direction; A second mirror unit reflecting a part of the light source transmitted through the first mirror unit to transmit the substrate; A first light amount detecting unit detecting a light amount of the light source transmitted when the light source reflected through the second mirror unit passes through the substrate; A second light amount detector for detecting a light amount from a part of the light source reflected through the first mirror in a specific direction; And, A quality inspection unit which compares the amounts of light detected by the first and second light quantity detection units to remove noise included by external factors and inspects a quality state of the substrate surface in the state where the noise is removed; Quality inspection apparatus of the substrate, characterized in that comprising a. The apparatus of claim 10, wherein the illumination unit comprises one of a light source, an infrared light source, and an LED light source of the xenon lamp. The apparatus of claim 10, wherein the second mirror unit is disposed at an angle within a range of 10 ° to 90 ° to determine an incident angle of the light source. The method of claim 10 or 11, And a slit for setting an irradiation range of a light source to set an inspection area for a specific portion of the substrate at the tip of the lighting unit. The apparatus of claim 13, wherein the front end of the slit comprises a filter member for transmitting only a wavelength band of a specific band from a light source. 11. The apparatus of claim 10, wherein the first mirror unit comprises a half mirror. A first step of selecting an image of a specific area to be observed from the entire image of the captured shadow image; Noises included in the image by tabulating pixel values (brightness) of horizontal / vertical lines in the image of the selected specific region and extracting average values of adjacent pixel values from the table pixel values by a moving average method. A second step of reducing primarily; The image obtained by adding or averaging horizontal line columns A1, A2, A3, A4, A5, ..., An from the average value of the extracted pixels in a state where noise is reduced primarily by the moving average method from the second step. A third step of outputting a signal; And, A fourth step of inspecting a quality state of the surface of the substrate by determining whether the image signal output from the third step exceeds a preset threshold; Quality inspection method of the substrate, characterized in that to proceed. 17. The method of claim 16, wherein in the third step, the output of the image signal according to the sum (or average) result is obtained by the following equation.

A first step of irradiating a light source from the illumination unit; A second step of detecting a light amount by receiving a portion of the light source irradiated from the first step; A third step of detecting an amount of light of the transmitted light source when another part of the light source irradiated from the first step passes the substrate; A fourth step of extracting and removing noise generated according to characteristics of the substrate by comparing the amounts of light detected from the second and third steps; A fifth step of inspecting a quality state on the surface of the substrate by comparing the amount of light from which the noise is removed from the fourth step with a boundary condition of a reference value for a flatness of the substrate which is a preset threshold; Quality inspection method of the substrate, characterized in that to proceed.

Images