JP4892943B2 - Density unevenness inspection device - Google Patents

Description

  The present invention relates to a density unevenness inspection apparatus for inspecting minute density fluctuations of a pattern having a uniform density formed on a substrate.

  In density unevenness inspection of a pattern with a uniform density formed on a substrate, a transmission image is captured using coaxial transmission illumination or plane illumination, and the intensity (brightness) of the light in each image is compared. And normal part were visually recognized.

  However, in the above method, in the inspection of the black matrix unevenness of the lattice-like periodic pattern, especially the black matrix unevenness having a large opening, the contrast between the uneven portion and the normal portion cannot be improved, and the intensity difference is processed. However, when the contrast of the original image is low, there is a problem that only a lower inspection ability than the visual sensory inspection method can be achieved.

  As a method for solving the above problem, the diffracted light in the periodic pattern is captured by obliquely transmitted illumination, thereby imaging a subtle variation of the periodic pattern, for example, a black matrix pattern, and inspecting the periodic pattern unevenness. A periodic pattern unevenness inspection apparatus has been proposed (see, for example, Patent Document 1).

However, in the above inspection apparatus, unevenness inspection is carried out by individually setting the angle at which defects are visible while shaking the substrate at various angles with respect to the light source such as transmitted light, specular reflected light, scattered light, etc. There is a problem that minute density unevenness is often seen.
JP-A-2005-147918

  The present invention has been devised in view of the above problems, and an object thereof is to provide a density unevenness inspection apparatus capable of inspecting minute density fluctuations of a periodic pattern having a uniform density formed on a substrate. And

In order to achieve the above object in the present invention, first, in claim 1, there is provided an apparatus for inspecting density unevenness of a pattern formed on a substrate, comprising a first imaging means (11) and a first illumination. At least one first inspection means (10) comprising means (21), at least one second inspection means (20) comprising second imaging means (12) and second illumination means (22); An image processing means (30), a determination means (40), and a control means (50), and an illumination angle (α) of the first illumination means (21) with respect to the first imaging means (11). When the second and illumination angle (beta) of the second illumination means with respect to the imaging means (12) (22) but set to respective different angles tare is, first of the first inspection means (10) An illumination axis of one illumination means (21) and a stripe pattern formed on the substrate; And the illumination angle (θ) formed by the illumination axis of the second illumination means (22) of the second inspection means (20) and the stripe pattern formed on the substrate. the have, and at least the illumination angle (gamma) and the illumination angle (theta) and either 38 ° to 52 ° is set in a range of not feature a be that concentration irregularity inspection device Rukoto of Is.

  By using the density unevenness inspection apparatus of the present invention, it is possible to inspect a minute density change of a colored filter such as a color filter substrate or a black matrix pattern with high sensitivity.

Embodiments of the present invention will be described below.
FIG. 1 is a schematic configuration diagram showing an embodiment of the density unevenness inspection apparatus of the present invention.
As shown in FIG. 1, the density unevenness inspection apparatus 100 includes at least one first inspection unit 10 including a first imaging unit 11 including a line camera and a first illumination unit 21 that illuminates the processing substrate. , At least one second inspection means 20 comprising a second imaging means 12 comprising a line camera or the like, and a second illumination means 22 for illuminating the processing substrate, a first imaging means 11 and a second imaging means. 12 includes an image processing unit 30 that captures and analyzes the image captured in 12, a determination unit 40 that determines pass / fail based on the image analysis result, and a control unit 50 that controls the entire apparatus.

  The illumination angle α of the first illumination means 21 with respect to the first imaging means 11 of the first inspection means 10 and the illumination angle β of the second illumination means 22 with respect to the second imaging means 12 of the second inspection means 20 are: In the case where the stripe pattern has a stripe pitch of 0.2 mm, the illumination angle α is preferably 45 °, for example, and the illumination angle β is preferably 15 °, for example.

FIG. 3 is a schematic top view showing an example of the arrangement of the first inspection means 10 and the second inspection means 20 for inspecting the density unevenness of the processing substrate 71 using the density unevenness inspection apparatus of the present invention.
The first inspection means 10 and the second inspection means 20 are shielded by the light shielding plate 61, and the illumination angle γ formed by the illumination axis of the first illumination means 21 and the stripe pattern formed on the substrate, and the first The illumination angle θ formed by the illumination axis of the second illumination means 22 and the stripe pattern formed on the substrate is set such that either the illumination angle γ or the illumination angle θ is in the range of 38 ° to 52 °. Here, 45 ° is set as the illumination angle γ and 90 ° is set as the illumination angle θ.

Chi I sand, density unevenness inspection device of FIG. 3, the first inspection means 10 for illuminating angle α of the first lighting unit 21 with respect to the first image pickup means 11 is set to 45 °, the first illumination means The illumination angle γ formed by the 21 illumination axes and the stripe pattern formed on the processing substrate 71 is set to 45 °, and six are arranged in the width direction of the processing substrate 71.
Further, on the opposite side of the light shielding plate 61, the second inspection unit 10 in which the illumination angle α of the second illumination unit 22 with respect to the second imaging unit 12 is set to 15 ° is illuminated by the second illumination unit 22. The illumination angle θ formed by the shaft and the stripe pattern formed on the processing substrate 71 is arranged at 90 °.

A line camera is used for the first imaging unit 11 and the second imaging unit 12.
Further, the first illumination means 21 and the second illumination means 22 are bar-shaped in accordance with the field of view of the first imaging means 11 and the second imaging means 12 whose irradiation range is composed of line cameras so that the emitted light can be used effectively. It is desirable that For example, transmission light, bar illumination using an LED array, bar illumination using an optical fiber, and a combination of a lamp and a cylindrical lens. This is an example and the present invention is not limited to this.
The positional relationship between the illumination unit and the imaging unit is set so that the approximate center of the irradiation range is the field of view of the imaging unit.

One of the causes of density unevenness (defects) that can be seen only under specific conditions is disturbance of diffracted light due to minute disturbance of the stripes of the colored filter formed on the processing substrate 71. For this reason, it has been found that when the illumination is applied parallel to the stripes of the colored filter, it appears with the best contrast, and when it is applied vertically, it is almost invisible.
However, the stripe direction of the colored filter formed on the processing substrate is parallel to the direction perpendicular to the transport direction, so it is detected when the illumination means and line camera are installed at a right angle to the transport direction as in the conventional inspection equipment. Variation in force will occur.

In the density unevenness inspection apparatus of the present invention, any one of the illumination angle γ and the illumination angle θ formed by the illumination axis of the illumination means of the inspection means and the stripe pattern formed on the processing substrate is in the range of 38 ° to 52 °. Thus, the same detection power is obtained regardless of the stripe direction of the coloring filter. The detection power is lower than that in the case of being parallel to the stripe, but the detection power is practically sufficient.

  Further, the illumination angle γ and illumination angle θ formed by the illumination axis of the illumination means and the stripe pattern formed on the processing substrate are the illumination angle with respect to the stripe pattern of the vertical stripe and the horizontal stripe, and the imaging means When the relative sensitivity is expressed as a vertical axis, a graph as shown in FIG. 2 is obtained. If the relative sensitivity is in the range of 38 ° to 52 °, the sensitivity decrease is 0.1 or less, and sufficient detection power can be secured. .

Of course, it is possible to rotate the substrate in advance so that the stripes of the colored filter are always parallel to the illumination means and the imaging means, but a rotation mechanism is required and the dimensions of the apparatus, the dimensions of the illumination means, The number of line cameras must match the long side of the board.
In addition, in the processing substrate 71 having a plurality of types of regions, called a hybrid, right-angle stripes and parallel stripes may be mixed on a single substrate, and in this case, it cannot be handled only by substrate rotation. Two-pass inspection such as rotating the substrate in the middle is required.

Another cause of density unevenness (defects) that can be seen only under specific conditions is a protruding foreign material having a height. When the foreign matter is transparent or present in a black matrix pattern having a lattice shape or a stripe shape, it cannot be detected by a normal transmitted light inspection.
For this reason, it is possible to capture the scattered light from the protrusion defect with good contrast by directing the imaging unit and the illumination unit obliquely from the same direction toward the processing substrate so as to capture only the scattered light.

With respect to the protruding foreign matter intended by the second inspection means 20, it is known that there is no influence of the stripe direction of the colored filter, so there is no problem even if the illumination angle θ is an arbitrary value. It has been confirmed that a part of the defect that disturbs the target diffracted light of the first inspection means 10 can be seen at the same time even in the above configuration.
For this reason, the second inspection means 20 is also expected to capture density unevenness (defects) that are difficult to see with the first inspection means 10.

Examples of the present invention will be described below.
First, a first illuminating means 21 in which a 100 W halogen lamp is incident from one end face on a transmission light having an irradiation width of 500 mm equipped with a first imaging means 11 comprising a 2048 bit line camera and a condensing cylindrical lens. First transmission means 10 comprising: a second imaging means 12 comprising a 2048-bit line camera, and a transmission light having an irradiation width of 1600 mm equipped with a condensing cylindrical lens, two 350 W metal halide lamps via a fiber The density unevenness inspection apparatus includes a second inspection unit 20 including a second illumination unit 22 that is incident from both end faces, an image processing unit 30 including a computer, a determination unit 40, and a control unit 50. 100a was constructed (see FIG. 1).
Here, the illumination angle α of the first illumination means 21 relative to the first imaging means 11 is set to 45 °, and the illumination angle β of the first illumination means 22 relative to the second imaging means 12 is set to 15 °.

Next, when inspecting the density unevenness (defect) of the processing substrate 71 (here, the color filter substrate) multifaceted by using the density unevenness inspection apparatus 100a, the illumination axis and the processing substrate of the first illumination means 21 are used. Six sets of the first inspection means 10 in which the illumination angle γ formed by the stripe pattern formed on 71 is set to 45 ° are arranged (see FIG. 3).
The visual field width of the first imaging means 11 composed of a line camera is 340 mm (camera visual field width direction), and each camera is arranged with an overlap of 40 mm (converted value in the river width direction), and has a total visual field width of 1240 mm. I gave it. The lens is a 35 mm single-lens reflex lens with f = 50 mm and F1.2.

On the other hand, as shown in FIG. 3, the illumination angle θ formed by the illumination axis of the second illumination means 22 and the stripe pattern formed on the substrate is set to 90 °, and the second composed of a 2048-bit line camera. Six imaging means 12 were arranged to constitute the second inspection means 20 (see FIG. 3).
The visual field width of the second imaging means 12 composed of a line camera is 340 mm, and is arranged so as to be able to overlap by 40 mm, and has a visual field width of 1240 mm as a whole. The lens is a 35 mm single-lens reflex lens with f = 50 mm and F1.2.
The first inspection means 10 and the second inspection means 20 are shielded by a light shielding plate 61, and the first inspection means 10 are shielded by a light shielding plate 62 so that they are not affected by each illumination means. .

With the arrangement configuration of the first inspection means 10 and the second inspection means 20 shown in FIG. 3, a pattern image such as a colored filter and a black matrix of the processing substrate 71 is captured by the first imaging means 11 and the second imaging means. The image processing unit 30 performs image processing, and the determination unit 40 detects a portion having a large luminance fluctuation as a defect.
This result is presented to the inspector through a screen display, a warning lamp, and the like, and is transferred to the downstream process apparatus and the management system by communication.
The control unit 50 controls a series of operations of transporting the processing substrate, capturing an image, image processing, and determination processing.

First, a first illuminating means 21 in which a 100 W halogen lamp is incident from one end face on a transmission light having an irradiation width of 500 mm equipped with a first imaging means 11 comprising a 2048 bit line camera and a condensing cylindrical lens. 150 W halogen lamps are incident from both end faces on a transmission light having an irradiation width of 500 mm equipped with a first inspection means 10 comprising: a second imaging means 12 comprising a 2048-bit line camera and a condensing cylindrical lens. The second non-uniformity inspection apparatus 100b is configured by the second inspection unit 20 including the second illumination unit 22, the image processing unit 30 including the computer, the determination unit 40, and the control unit 50 (see FIG. 1).
Here, the illumination angle α of the first illumination means 21 relative to the first imaging means 11 is set to 45 °, and the illumination angle β of the first illumination means 22 relative to the second imaging means 12 is set to 15 °.

Next, when inspecting the density unevenness (defect) of the processing substrate 71 (here, the color filter substrate) multifaceted by using the density unevenness inspection apparatus 100b, as shown in FIG. The first inspection means is composed of a first imaging means 11 composed of a 2048-bit line camera with an illumination angle γ formed by 21 illumination axes and a stripe pattern formed on the processing substrate 71 set to 45 °. Six 10 were arranged (see FIG. 4).
In addition, the illumination angle θ formed by the illumination axis of the second illumination means 22 and the flow direction of the processing substrate 71 is set to 45 °, and the second imaging means 12 is formed of a 2048-bit line camera. Six second inspection means 10 are arranged (see FIG. 4).
The first inspection means 10 and the second inspection means 20 are shielded by the light shielding plates 61 and 62 so that they are not affected by each illumination means.

  The visual field width of the first imaging means 11 composed of a line camera is 340 mm (camera visual field width direction) and 240 mm (river width direction converted value), and each camera is arranged with an overlap of 40 mm (river width direction converted value). The total viewing width was 1240 mm. The lens is a 35 mm single-lens reflex lens with f = 50 mm and F1.2.

  On the other hand, the visual field width of the second imaging means 12 composed of a line camera is 340 mm (camera visual field width direction) and 240 mm (river width direction converted value), and is arranged so as to be able to overlap by 40 mm. Has a viewing width of. The lens is a 35 mm single-lens reflex lens with f = 50 mm and F1.2.

With the arrangement configuration of the first inspection means 10 and the second inspection means 20 shown in FIG. 4, a pattern image such as a colored filter and a black matrix of the processing substrate 71 is captured by the first imaging means 11 and the second imaging means. The image processing unit 30 performs image processing, and the determination unit 40 detects a portion having a large luminance variation as a defect.
This result is presented to the inspector through a screen display, a warning lamp, and the like, and is transferred to the downstream process apparatus and the management system by communication.
The control unit 50 controls a series of operations of transporting the processing substrate, capturing an image, image processing, and determination processing.

First, two 350 W metal halide lamps were incident from both end faces through a fiber onto a transmission light with an irradiation width of 2200 mm equipped with a first imaging means 11 comprising a 2048-bit line camera and a condensing cylindrical lens. A 350 W metal halide lamp in a transmission light with an irradiation width of 2200 mm equipped with a first inspection means 10 comprising a first illumination means 21, a second imaging means 12 comprising a 2048-bit line camera, and a condensing cylindrical lens. The second inspecting unit 20 includes a second illuminating unit 22 in which two light beams are incident from both side end faces via a fiber, an image processing unit 30 including a computer, a determination unit 40, and a control unit 50. Thus, the density unevenness inspection apparatus 100c was configured (see FIG. 1).
Here, the illumination angle α of the first illumination means 21 relative to the first imaging means 11 is set to 45 °, and the illumination angle β of the first illumination means 22 relative to the second imaging means 12 is set to 15 °.

Next, when inspecting the density unevenness (defect) of the processing substrate 71 (here, the color filter substrate) multifaceted by using the density unevenness inspection apparatus 100c, as shown in FIG. The illumination angle γ formed by the illumination axis of 21 and the stripe pattern formed on the processing substrate 71 is set to 45 °, six first imaging means 11 comprising 2048-bit line cameras are arranged, and the first inspection is performed. Means 10 was constructed (see FIG. 5).
In addition, the illumination angle θ formed by the illumination axis of the first illumination means 22 and the stripe pattern formed on the processing substrate 71 is set to 45 °, and the second image pickup means 12 composed of a 2048-bit line camera is provided. A table was arranged to constitute the second inspection means 20 (see FIG. 5).
The first inspection means 10 and the second inspection means 20 are shielded by a light shielding plate 61 so that they are not affected by each illumination means.

  The visual field width of the first imaging means 11 composed of a line camera is 340 mm (camera visual field width direction) and 240 mm (river width direction converted value), and each camera is arranged with an overlap of 40 mm (river width direction converted value). The total viewing width was 1240 mm. The lens is a 35 mm single-lens reflex lens with f = 50 mm and F1.2.

  On the other hand, the visual field width of the second imaging means 12 composed of a line camera is 340 mm (camera visual field width direction) and 240 mm (river width direction converted value), and is arranged so as to be able to overlap by 40 mm. Has a viewing width of. The lens is a 35 mm single-lens reflex lens with f = 50 mm and F1.2.

With the arrangement configuration of the first inspection means 10 and the second inspection means 20 shown in FIG. 5, a pattern image such as a colored filter and a black matrix of the processing substrate 71 is captured by the first imaging means 11 and the second imaging means. The image processing unit 30 performs image processing, and the determination unit 40 detects a portion having a large luminance variation as a defect.
This result is presented to the inspector through a screen display, a warning lamp, and the like, and is transferred to the downstream process apparatus and the management system by communication.
The control unit 50 controls a series of operations of transporting the processing substrate, capturing an image, image processing, and determination processing.

  As described above, by inspecting the density unevenness of the processing substrate such as the color filter using the density unevenness inspection apparatus of the present invention, the defect that can be seen only under a specific condition generated in the pattern of the colored filter or the like on the processing substrate is obtained. Inspection with high sensitivity becomes possible.

It is a schematic block diagram which shows one Example of the density nonuniformity inspection apparatus of this invention. It is explanatory drawing which shows the relative sensitivity of an imaging means when the illumination angle formed with the illumination axis of an illumination means and the stripe pattern formed in the process board | substrate is changed. It is a schematic configuration top view showing an example of an inspection apparatus for inspecting density unevenness of a processing substrate using the density unevenness inspection apparatus of the present invention. It is a schematic top view showing another example of an inspection apparatus for inspecting density unevenness of a processing substrate using the density unevenness inspection apparatus of the present invention. It is a schematic top view showing another example of an inspection apparatus for inspecting density unevenness of a processing substrate using the density unevenness inspection apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st inspection means 11 ... 1st imaging means 21 ... 1st illumination means 20 ... 2nd inspection means 12 ... 2nd imaging means 22 ... 2nd illumination means 30 ... Image Processing means 40... Determination means 50... Control means 61 and 62... Shading plate 71 .. Processing substrates 100, 100 a, 100 b and 100 c. Illumination angle β of the illumination means 21... Illumination angle γ of the second illumination means 22 relative to the second imaging means 12... Formed by the illumination axis of the first illumination means 21 and the stripe pattern formed on the processing substrate 71. Illumination angle θ ... Illumination angle formed by the illumination axis of the second illumination means 22 and the stripe pattern formed on the processing substrate 71

Claims (1)

An apparatus for inspecting density unevenness of a pattern formed on a substrate, comprising at least one first inspection means (10) comprising a first imaging means (11) and a first illumination means (21); At least one second inspection means (20) comprising two imaging means (12) and second illumination means (22), image processing means (30), determination means (40), and control means (50). ), An illumination angle (α) of the first illumination means (21) with respect to the first imaging means (11), and a second illumination means (22) with respect to the second imaging means (12). in the illumination angle (beta), but set to respective different angles tare is, a first lighting unit (21) illumination axis and the stripe pattern formed on the substrate of the first inspection means (10) The illumination angle (γ) to be formed and the second illumination of the second inspection means (20). An illumination angle (θ) formed by the illumination axis of the means (22) and a stripe pattern formed on the substrate, and at least one of the illumination angle (γ) and the illumination angle (θ) There density unevenness inspection apparatus characterized that you have been set in the range of 38 ° to 52 °.