KR20070099398A - Apparatus for inspecting substrate and method of inspecting substrate using the same - Google Patents

Abstract

An inspecting apparatus and a substrate inspecting method using the same are provided to check a fault of a pattern by applying an inspection light to a substrate in a coherent state and sensing brightness of the inspection light. A substrate inspecting method includes the steps of: applying inspecting light on a substrate(140) where a pattern(142) is formed; detecting the brightness of the inspecting light reflected from the substrate; and determining whether the pattern is faulty from the detected brightness. The inspecting light is applied to the substrate in a coherent state.

Description

Substrate Inspection System and Substrate Inspection Method Using the Same {APPARATUS FOR INSPECTING SUBSTRATE AND METHOD OF INSPECTING SUBSTRATE USING THE SAME}

1 is a cross-sectional view of a liquid crystal display device;

2 is a view showing a substrate inspection apparatus according to a first embodiment of the present invention,

3 is a view for explaining the arrangement of the camera in the substrate inspection apparatus according to the first embodiment of the present invention,

4 is a view for explaining the configuration of the camera in the substrate inspection apparatus according to a first embodiment of the present invention,

5 is a view for explaining the inspection light emitted from the substrate inspection apparatus according to the first embodiment of the present invention,

6A and 6B are views for explaining the relationship between the size of the pixel region and the optical resolution;

7 is a diagram for explaining diffraction of inspection light;

8 is a view for explaining the shift of the reflected light according to the height of the pattern,

9a and 9b are photographs showing the diffraction spectrum according to the height in the pattern,

10 is a view for explaining the change in luminance according to the height of the pattern,

11 is a photograph showing a luminance image obtained through an experiment,

12 is a view showing a substrate inspection apparatus according to a second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10 detection unit 20 light source unit

21: lamp 22: lamp cover

30: camera 31: imaging unit

35 lens 40 seating part

50: driving unit 141: insulated substrate

142: pattern

The present invention relates to a substrate inspection apparatus and a substrate inspection method using the same, and more particularly, to a substrate inspection apparatus capable of accurately measuring a pattern defect on a substrate and a substrate inspection method using the same.

Recently, flat panel displays such as liquid crystal displays and organic light emitting diodes (OLEDs) have been used in place of existing CRTs.

Various patterns are formed in these display devices. For example, a pattern such as a black matrix and a color filter is formed on a color filter substrate of a liquid crystal display device. It should be formed with a uniform thickness of such a pattern. In the case of the color filter, if the thickness is not uniform, it may cause staining on the screen.

In the manufacturing process of the display device, the substrate is inspected to determine whether the height of these patterns is uniformly formed.

However, the conventional substrate inspection has a problem that accurate measurement is difficult because the operator visually determined whether the pattern is defective while illuminating light on the substrate on which the pattern is formed.

Accordingly, it is an object of the present invention to provide a substrate inspection method for accurately measuring a defect of a pattern.

Another object of the present invention is to provide a substrate inspection apparatus for accurately measuring a defect of a pattern.

An object of the present invention is the step of applying the inspection light to the substrate is a pattern is formed; Sensing the luminance of the inspection light reflected from the substrate; It is achieved by a substrate inspection method comprising determining whether the pattern is defective from the sensed brightness.

The inspection light is preferably applied to the substrate in a coherent state.

It is preferable that the said inspection light is a beneficiation.

It is preferable that the luminance is obtained while scanning the inspection light onto the substrate.

In the scan, the incident angle of the inspection light to the substrate is constant, and the brightness is preferably sensed at a predetermined position at the incident point of the substrate.

The luminance is preferably obtained by using a line camera including an imaging unit arranged in a line.

The imaging unit preferably includes a charge-coupled device (CCD).

The reflected inspection light is preferably incident on the line camera via a lens.

A plurality of pixel areas are formed on the substrate, and the optical resolution of each imaging unit is preferably between 100% and 300% of the pixel area size.

The optical resolution R of each imaging unit is (bf) * D / f (where b is the distance between the lens and the incident point, f is the focal length of the lens, and D is the size of each imaging unit ( size)), and the optical resolution of each imaging unit is preferably adjusted by changing the distance between the lens and the incident point.

Preferably, the distance a between the lens and the line camera is 90% to 110% of the D * R / b value.

The pattern preferably includes at least one of a black matrix, a color filter, and a column spacer.

Preferably, the brightness varies depending on the height of the pattern.

An object of the present invention is the step of applying a line-shaped inspection light to the substrate on which the pattern is formed; Sensing the luminance of the inspection light reflected from the substrate using a line camera; It can also be achieved by a substrate inspection method comprising determining whether the pattern is defective from the sensed brightness.

It is preferable that the luminance is obtained while scanning the inspection light onto the substrate.

In the scan, the incident angle of the inspection light to the substrate is constant, and the brightness is preferably sensed at a predetermined position at the incident point of the substrate.

The reflected inspection light is incident to the line camera through a lens, and the substrate includes a plurality of pixel regions, and the line camera includes an imaging unit arranged in a line, and the optical resolution of each imaging unit. Optical resolution is preferably between 100% and 300% of the pixel area size.

The optical resolution R of each imaging unit is (bf) * D / f (where b is the distance between the lens and the incident point, f is the focal length of the lens, and D is the size of each imaging unit ( size)), and the optical resolution of each imaging unit is preferably adjusted by changing the distance between the lens and the incident point.

Another object of the present invention and the seating portion that is the substrate is a pattern is formed; A detection unit positioned above the seating unit, the light source unit supplying inspection light to the substrate, and a camera configured to sense a brightness of the inspection light reflected by the substrate; A driving unit for relatively moving the seating unit and the detection unit; It is achieved by including a control unit for determining whether the pattern is defective from the brightness detected by the camera.

The inspection light supplied by the light source unit is preferably coherent.

It is preferable that the said inspection light is a beneficiation.

The light source unit preferably includes a slit for limiting the emission angle of the emitted light.

The camera preferably comprises a line camera.

Preferably, the detection unit further includes a lens located between the camera and the seating unit.

In the relative movement of the seating portion and the detection portion, it is preferable that the relative position of the reflection point of the substrate and the light source portion and the relative position of the reflection point of the substrate and the camera are kept constant.

The pattern preferably includes at least one of a black matrix, a color filter, and a column spacer.

In various embodiments, like reference numerals refer to like elements, and like reference numerals refer to like elements in the first embodiment and may be omitted in other embodiments.

In the following embodiment, a color filter substrate of a liquid crystal display device is described as an example, but the present invention can also be applied to a thin film transistor substrate. The invention can also be applied to substrates of other display devices such as organic light emitting devices (OLEDs), electrophoretic display devices (EPDs), plasma display devices (PDPs).

In the following description, the size of the pixel area refers to the length of one side of the square having the same area as the area of the pixel area. Each imaging unit has a square shape, and a "size of an imaging unit" means the length of one side of an imaging unit. Each imaging unit picks up a square area of an object to be imaged, and "optical resolution of an imaging unit" refers to the length of one side of the square area to be picked up.

1 is a cross-sectional view of a liquid crystal display device.

The liquid crystal display device 100 includes a thin film transistor substrate 110, a color filter substrate 120, and a liquid crystal layer 130 disposed on both substrates 110 and 120.

Referring to the thin film transistor substrate 110, a plurality of thin film transistors 112 are formed on the insulating substrate 111. The thin film transistor 112 is covered with a protective layer 113 made of an inorganic film or an organic film, and a portion of the protective layer 113 is removed to form a contact hole 114 exposing the thin film transistor 112. The pixel electrode 115 made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is connected to the thin film transistor 112 through the contact hole 114.

Referring to the color filter substrate 120, a grid-like black matrix 122 is formed on the insulating substrate 121. The black matrix 122 may be made of an organic material including a black pigment, and is formed to correspond to the thin film transistor 112 and the wiring (not shown) of the thin film transistor substrate 110.

The color filter 123 is formed between the black matrices 122. The color filter 123 is composed of organic materials and includes three sub layers 123a, 123b, and 123c having different colors. The common electrode 125 made of an overcoat layer 124 and a transparent conductive material is formed on the black matrix 122 and the color filter layer 123. The column spacer 126 is formed on the common electrode 125. The column spacer 126 is formed to correspond to the black matrix 122 and maintains a gap between the substrates 110 and 120.

The arrangement state of the liquid crystal layer 130 disposed between the substrates 110 and 120 is determined by an electric field formed by the pixel electrode 115 and the common electrode 125. The light supplied from the lower portion of the thin film transistor substrate 110 passes through a polarizing plate (not shown) attached to the outside of the color filter layer 123 and the color filter substrate 120 after the transmittance is adjusted in the liquid crystal layer 130. Is given.

The patterns of the black matrix 122, the color filter layer 123, and the column spacer 126 described above are usually formed by coating and then exposing and developing the photosensitive organic layer.

Coating of the photosensitive organic layer is carried out by a method such as slit coating, spin coating or screen coating. However, if particles exist on the insulating substrate before coating, the thickness of the photosensitive organic layer is uneven, and thus the thickness of the pattern formed is uneven. The thickness of the pattern may be uneven due to the inflow of particles during the process of forming the pattern.

If the thickness of the pattern becomes uneven, the display quality is deteriorated. In particular, if the thickness of the color filter layer 123 becomes uneven, staining may occur on the screen.

Accordingly, after forming each pattern, whether the pattern is defective or not is measured. If a defect is measured in the pattern, the defective pattern is reworked or the substrate is discarded.

The present invention relates to an inspection apparatus and an inspection method for measuring a defect of a pattern.

2 is a view showing a substrate inspection apparatus according to a first embodiment of the present invention.

The substrate inspecting apparatus 1 includes a detector 10, a seat 40 positioned below the detector 10, and a driver 50 for linearly moving the seat 40. The substrate 140 to be inspected includes an insulating substrate 141 and a pattern 142 formed on the insulating substrate 141. The pattern 142 may be any one of a black matrix, a color filter layer, and a column spacer.

The detector 10 is fixed and includes a light source unit 20 for supplying inspection light to the substrate 140 and a camera 30 for sensing the luminance of the reflected light reflected from the substrate 140. As shown in FIG. 3, the camera 30 is composed of a pair. Each camera 30 has an area for sensing luminance, that is, a field of view (FOV). The width d1 of the FOV of each camera 30 is greater than half of the width d2 of the substrate 140. The FOV of the camera 30 partially overlaps, partly off the substrate 140. The lens 35 is positioned between the camera 30 and the substrate 140.

The light source unit 20 is disposed such that the incident light of the inspection light and the substrate 140 has a constant angle θ1. The light source unit 20 includes a lamp 21 generating light and a lamp cover 22 surrounding the lamp 21 and directing the light toward the substrate 140. The lamp cover 22 has one surface facing the substrate 140.

The configuration of the light source unit 20 may be variously modified as long as it can supply line type inspection light of uniform intensity. The light source unit 20 may include a point light source such as a halogen lamp or a metal-halide lamp, and an optical fiber converting the point light source into a linear light source.

The camera 30 is a line camera in which n imaging units 31 made of a charge-coupled device (CCD) are arranged in a line as shown in FIG. 4. Each imaging unit 31 has a square shape, the length of one side, that is, the size of the live unit 31 is represented by D. The imaging unit 31 of the camera 30 is arranged in parallel with the lamp 21. The camera 30 is disposed to form a predetermined angle θ2 with the incident point of the substrate 140.

The driver 50 moves the seat 40 so that the detector 10 scans the entire substrate 140. For the entire scan of the substrate 140, the length of the lamp 21 is preferably larger than the width d2 of the substrate 140.

When scanning the entire substrate 140, the angle θ1 between the incident point and the light source unit 20 and the angle θ2 between the incident point and the camera 30 are kept constant.

The intensity of the reflected light detected by the camera 30 changes according to the height of the pattern 142 at the time of scanning.

Although not shown, the substrate inspection apparatus 1 may further include a controller to determine whether the pattern 142 is defective based on the detected luminance value.

5 is a view for explaining inspection light emitted from the substrate inspection apparatus according to the first embodiment of the present invention.

The inspection light is not parallel light at a portion close to the light source unit 20, but is incident in a substantially parallel state when it enters the substrate 140. This substantially parallel state is called a coherent state. In order to make the coherent inspection light, the distance c between the incident point and the light source 20 must be maintained at a constant value, for example, about 3 m or more.

In order to inspect the substrate 140 from the reflected inspection light, the camera 30 must have an appropriate optical resolution. That is, the optical resolution of each imaging unit 31 of the camera 30 should have an appropriate range. This will be described by exemplifying the color filter substrate 120 as an inspection object.

As illustrated in FIG. 6A, a plurality of pixel areas are formed in the color filter substrate 120. A pixel area is a group of a plurality of subpixels, which is a basic unit constituting a screen. As shown in the drawing, the pixel region includes three regions representing red, blue, and green, respectively, and has a square shape having a length of one side d3.

Each imaging unit 31 picks up a square unit imaging area of the substrate 140. The optical resolution R, which is the length of one side of the unit imaging area, is preferably 100% to 300% of the length d3 of one side of the pixel area, that is, the size of the pixel area.

Normal failures occur over several pixel regions. If the optical resolution R is smaller than 100% of the size d3 of the pixel area, that is, the unit imaging area is smaller than the pixel area, the defect cannot be detected for optical reasons. On the contrary, if the optical resolution R is larger than 300% of the size d3 of the pixel region, the resolution may decrease, so that even if a defect occurs, the optical resolution R may not be recognized as a defect or a position where the defect occurs may not be determined.

On the other hand, as shown in FIG. 6B, the pixel area may not be square. In this case, the size d3 of the pixel region may be based on the length of one side of the square having the same area as the pixel region.

Hereinafter, a method of adjusting the optical resolution R will be described.

The optical resolution R is determined by the following equation.

[Equation 1]

R = (b-f) * D / f

Here, b is the distance between the lens 35 and the incidence point shown in FIG. 2, f is the focal length of the lens 35, and D is the size of each imaging unit 31 shown in FIG.

On the other hand, the distance b between the lens 35 and the incident point is expressed by the following expression (2) from the equation (1).

[Equation 2]

b = f * (R / D + 1)

In the inspection, the optical resolution R is usually adjusted by changing the distance b between the lens 35 and the incident point without replacing the camera 30 and the lens 35. For example, when the size d3 of the pixel region is 300 μm, the size D of the imaging unit 31 is 14 μm, and the focal length f of the lens 35 is 60 μm, the optical resolution R In order to be 500 µm, the distance b between the lens 35 and the incident point may be adjusted to about 2202 mm by Equation 2.

Of course, it is also possible to replace the camera 30 and the lens 35 to adjust the optical resolution (R).

On the other hand, the optical resolution R is related to the number n of the imaging units 31 and the width d1 of the FOV.

For example, it is assumed that two cameras 30 are provided, the width d2 of the substrate 140 is 1500 mm, and the width d1 of the FOV is 800 mm, as shown in FIG. 3.

If the desired optical resolution R is 500 mu m, the number n of the imaging units 31 should be d1 / R, about 1600. If the number n of the imaging units 31 of the camera 30 is smaller than 1600, three or more cameras 30 should be used, or the optical resolution R should be increased.

In this way, the number of the cameras 30, the number n of the imaging units 31, and the optical resolution R have a close relationship.

When the distance b between the lens 35 and the incident point is determined according to the desired optical resolution R, the distance a between the lens 35 and the camera 30 shown in Fig. 2 is determined by the following equation (3). do.

[Equation 3]

a = (D / R) * b

In the case illustrated above, the calculated value a is about 62 mm. The distance a between the lens 35 and the camera 30 is adjusted to focus the camera 30 and may be adjusted between 90% and 110% of the calculated value.

7 is a diagram for explaining diffraction of inspection light.

The pattern 142 formed on the substrate 140 may be on a lattice in the case of a black matrix, on a line arranged at regular intervals in the case of a color filter, or on a dot uniformly arranged in the case of a column spacer.

Such a pattern 142 acts as a diffracting grating on incident inspection light. Therefore, the light incident from the light source 20 to the pattern 142 is diffracted and reflected while forming a spectrum divided by wavelength.

Looking at the spectrum of light reflected and diffracted by the pattern 142, it can be seen that the intensity varies depending on the wavelength.

Hereinafter, the reason why the luminance difference occurs in the reflected light recognized by the camera 30 according to the height of the pattern 142 will be described with reference to FIGS. 8 to 10.

8 is a view for explaining the shift of the reflected light according to the height of the pattern, 9a and 9b is a photograph showing the diffraction spectrum according to the height in the pattern, and FIG. 10 is a view for explaining the change in luminance according to the height of the pattern. .

The height of the pattern 142 may vary depending on the position due to defects such as particles. The patterns 142 having different heights may appear in the form of dots on the substrate 140 or may appear in the form of lines.

In FIG. 8, it can be seen that the path of the reflected light is different depending on the height of the pattern 142. That is, in the case of (a) reflected from the normal pattern 142a and (b) reflected from the high pattern 142b, the height of the reflection point is different so that the reflected light shifts.

9A shows a diffraction spectrum when the height of the pattern 142 is constant, and FIG. 9B shows a diffraction spectrum when the height of the pattern 142 is uneven.

In FIG. 9B, when the height of the pattern 142 is inconsistent, it can be seen that the shape indicated by the arrow is different from the surroundings. That is, the shift of the reflected light occurs according to the height of the pattern 142, and the luminance is changed.

Referring to FIG. 10, the shape of the diffraction spectrum is almost similar to that of (a) that is the normal pattern 142a and that of the high pattern 142b. However, the wavelengths recognized by the fixed camera 30 are different from each other.

In the case of (a), light of the wavelength having the highest intensity is recognized by the camera 30. On the other hand, in the case of (b), light having a wavelength having a relatively low intensity is recognized by the camera 30. Therefore, the camera 30 senses a lower luminance than the normal pattern 142a in the high pattern 142b.

Luminance sensing is performed while scanning the inspection light across the substrate 140. By scanning, the reflected light luminance in the entire pattern 142 is measured and combined. When the luminance data is combined as described above, a portion having a lower luminance than the surroundings is sensed, and a portion having an uneven height of the pattern 142 may be determined therefrom.

8 to 10 illustrate that the luminance is lowered when the pattern 142 is high. However, when the height of the pattern 142 is different, it is determined according to the positional relationship between the light source 20 and the camera 30 whether the brightness of the reflected light is high or low. That is, if the camera 30 detects light of relatively low intensity in the diffraction pattern of the light reflected from the pattern 142 having the normal height, the light reflected from the pattern 142 having another height may be detected more strongly. have.

There may be various criteria for determining the defect of the pattern 142 from the obtained luminance value. For example, the luminance value is digitized, and a portion where the luminance is higher than a predetermined level compared to the surroundings can be determined as defective. The defective part may be represented by a dot or a line.

If it is determined that the pattern 142 is defective, the pattern 142 may be removed and formed again, or the substrate 140 may be discarded.

11 is a photograph showing a luminance image obtained through an experiment.

FIG. 11 is an image of a color filter, and it is possible to observe that the luminance and the surroundings are different in the square-marked portion. Such defects are caused by particles flowing into the photosensitive organic layer after forming the photosensitive organic layer.

In addition to the points shown in FIG. 11, portions having different luminance may appear in a line or plane form.

Referring to Fig. 11, the pattern defect is clearly displayed, so that the defect determination is easy. On the other hand, the obtained luminance data can be variously modified and manipulated as necessary to be used for pattern defect determination.

12 is a view showing a substrate inspection apparatus according to a second embodiment of the present invention.

As described in the first embodiment, the inspection light from the light source 20 should be incident on the substrate 140 in a coherent state. In order to make the inspection light coherent, a considerable distance is required between the substrate 140 and the light source 20. For this reason, there exists a problem that the volume of the board | substrate inspection apparatus 1 becomes very large.

According to the second embodiment, the slit 22a is provided in the lamp cover 22 of the light source 20. The slit 22a limits the emission angle of the inspection light, whereby the inspection light is coherent even at a relatively short distance. Accordingly, the distance d2 between the light source 20 and the substrate 140 may be reduced, thereby reducing the size of the substrate inspection apparatus 1.

Although some embodiments of the invention have been shown and described, those skilled in the art will recognize that modifications can be made to the embodiments without departing from the spirit or principles of the invention. . It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

As described above, according to the present invention, a substrate inspection method for accurately measuring a defect of a pattern is provided.

In addition, according to the present invention, a substrate inspection apparatus for accurately measuring a defect of a pattern is provided.

Claims (26)

Applying inspection light to the substrate on which the pattern is formed; Sensing the luminance of the inspection light reflected from the substrate; And determining whether the pattern is defective from the detected luminance. The method of claim 1, And said inspection light is applied to said substrate in a coherent state. The method of claim 2, And said inspection light is a beneficiation. The method according to any one of claims 1 to 3, And said luminance is obtained while scanning said inspection light onto said substrate. The method of claim 4, wherein In the scan, The incident angle of the inspection light to the substrate is constant, and the brightness is detected at a predetermined position from the incident point of the substrate. The method of claim 5, And the luminance is obtained by using a line camera including an imaging unit arranged in a line. The method of claim 6, And the imaging unit includes a charge-coupled device (CCD). The method of claim 7, wherein And the reflected inspection light is incident on the line camera via a lens. The method of claim 8, A plurality of pixel regions are formed on the substrate. And optical resolution of each imaging unit is between 100% and 300% of the pixel area size. The method of claim 9, The optical resolution R of each imaging unit is (bf) * D / f (where b is the distance between the lens and the incident point, f is the focal length of the lens, and D is the size of each imaging unit ( size)), The optical resolution of each imaging unit is adjusted by varying the distance between the lens and the incident point. The method of claim 10, And a distance (a) between the lens and the line camera is 90% to 110% of the D * R / b value. The method of claim 4, wherein And the pattern comprises at least one of a black matrix, a color filter, and a column spacer. The method of claim 4, wherein And said brightness varies with the height of said pattern. Applying inspection light in a line form to the substrate on which the pattern is formed; Sensing the luminance of the inspection light reflected from the substrate using a line camera; And determining whether the pattern is defective from the detected luminance. The method of claim 14, And said luminance is obtained while scanning said inspection light onto said substrate. The method of claim 15, In the scan, The incident angle of the inspection light to the substrate is constant, and the brightness is detected at a predetermined position from the incident point of the substrate. The method of claim 16, The reflected inspection light is incident to the line camera through a lens, A plurality of pixel regions are formed on the substrate. The line camera includes an imaging unit arranged in a line, And optical resolution of each imaging unit is between 100% and 300% of the pixel area size. The method of claim 17, The optical resolution R of each imaging unit is (bf) * D / f (where b is the distance between the lens and the incident point, f is the focal length of the lens, and D is the size of each imaging unit ( size)), The optical resolution of each imaging unit is adjusted by varying the distance between the lens and the incident point. A seating part that is a substrate on which a pattern is formed; A detection unit positioned above the seating unit, the light source unit supplying inspection light to the substrate, and a camera configured to sense a brightness of the inspection light reflected by the substrate; A driving unit for relatively moving the seating unit and the detection unit; And a controller which determines whether the pattern is defective from the brightness detected by the camera. The method of claim 19, And the inspection light supplied by the light source unit is coherent. The method of claim 20, And said inspection light is a beneficiation. The method of claim 21, The light source unit substrate inspection apparatus comprising a slit for limiting the emission angle of the emitted light. The method of claim 21, And the camera comprises a line camera. The method of claim 23, wherein The detection unit further comprises a lens positioned between the camera and the seating portion. The method of claim 23, wherein In the relative movement of the seating portion and the detection portion, And a reflection point of the substrate and a relative position of the light source unit, and a reflection point of the substrate and the relative position of the camera are kept constant. The method of claim 23, wherein And the pattern includes at least one of a black matrix, a color filter, and a column spacer.

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