JP5304133B2 - Color filter inspection method - Google Patents

Description

  The present invention relates to a color filter inspection method, and in particular, when a colored pixel pattern is formed on a glass substrate by a photolithography method using a photomask, the photomask is exposed at a slight angle in plan view. The present invention relates to a color filter inspection method for detecting color loss and color overlap caused by the above.

  A color filter for a liquid crystal display device is generally manufactured by a so-called photolithography method. In this method, first, a coating film made of, for example, a black photosensitive resin is formed on a transparent glass substrate, and then pattern exposure to the coating film through a photomask having a predetermined pattern, development, and the like are performed. A light shielding pattern having an opening is formed. This shading pattern is called a black matrix.

Next, after a coating film made of a colored photosensitive resin is formed on a glass substrate on which a black matrix is formed, pattern exposure to the coating film through a photomask having a predetermined pattern, development, etc. This is a method of forming a colored pixel pattern having a shape.
When the color filter is a color filter of a plurality of colors (for example, three colors of red (R), green (G), and blue (B)), red (R), green (G), and blue (B) Each color photosensitive resin is used to sequentially form color filters of each color.

The colored pixel pattern formed in the opening of the black matrix on the glass substrate has a function of a color filter that allows white light incident on the opening of the black matrix to pass as predetermined colored light.
There is a gap in a plan view between the colored pixel pattern formed in the process of pattern exposure, development, etc. and the opening of the black matrix, so that white light does not pass through the gap as it is. The peripheral edge of the colored pixel pattern is formed so as to overlap (overlap) the edge of the opening.

  However, if a misalignment occurs when forming the colored pixel pattern, the peripheral edge of the colored pixel pattern and the opening end of the black matrix do not overlap, and a plane is formed between the colored pixel pattern and the black matrix opening. When a gap (color loss) occurs visually, white light that is not colored leaks from the gap. If a color filter having such a gap (color loss) is incorporated in a liquid crystal display device, light leaking from the gap (color loss) during screen display will be observed as a white point, which is not preferable for screen display.

In addition, when a positional shift occurs when forming a colored pixel pattern, a portion overlapping with another color filter is generated, resulting in color overlap. Colored pixel patterns are mixed by color overlap, and turbidity is observed in the display color. For this reason, after the colored pixel pattern is formed, an inspection for the presence of defects such as color loss and color overlap is performed.
In this inspection, in the formed colored pixel pattern, adjacent portions (colored pixels) are compared with each other, and a case where there is a difference between the portions (colored pixels) is detected as a defect. The method is often used.

  FIG. 1 is a plan view of an example of a color filter substrate in which a light shielding pattern (black matrix) (2) and a colored pixel pattern are sequentially formed on a glass substrate (1). This represents a stage where a red colored pixel pattern (3R) is formed as the colored pixel pattern.

Striped light-shielding patterns (2) having a width (W1) are formed at a pitch (P1) in the Y-axis direction with the longitudinal direction parallel to the X-axis direction in FIG. This light-shielding pattern (2) is a repetition of a ladder pattern having an opening (4). The striped red-colored pixel pattern (3R) is formed by overlapping the peripheral edge on the end of the light shielding pattern (2) so as to block the opening (4).
Although not shown, a striped blue colored pixel pattern and a green colored pixel pattern are formed adjacent to the red colored pixel pattern (3R).

  2 is a cross-sectional view taken along line AA in FIG. As shown in FIG.1 and FIG.2, the opening part (4) of the light-shielding pattern (2) is equivalent to 1 pixel area | region of the colored pixel which uses the white light (W) to pass as colored light (R). The comparison inspection method compares the pixel areas 5A and 5B in FIG. 1 adjacent to each other (one pixel area of adjacent colored pixels) in the colored pixel pattern vertically and horizontally, and the pixel area (5). The case where there is a difference between them is regarded as a defect.

In recent years, as typified by thin TVs with large screens, liquid crystal display devices tend to have large screens. Therefore, the color filter constituting the liquid crystal display device is also enlarged.
When forming a colored pixel using a photolithography method, for example, pattern exposure is performed on the colored photosensitive resin through a photomask having a predetermined exposure pattern. In the pattern exposure to the coating film of the colored photosensitive resin, the exposure apparatus uses a photomask based on the position mark formed at the same time as the light-shielding pattern (2) on the glass substrate so as not to cause a position shift in the pattern exposure. After performing the above alignment, exposure is performed.

  However, the alignment by the exposure apparatus is not always performed completely. For example, where the angles of the glass substrate and the photomask should be parallel, the photomask may have a slight angle in plan view. Therefore, for example, the glass substrate and the photomask have an inclination of 1 °, and as a result, the color pixel pattern to be formed may be misaligned.

FIG. 3 is a plan view showing an example of color loss (N1) occurring in the color filter substrate. In FIG. 3, a light-shielding pattern (2) having an opening is formed on a glass substrate (1), and then a striped red colored pixel pattern (3R) and a green colored pixel pattern (3G) are formed. It represents the stage.
Each of the plurality of stripe-shaped light shielding patterns (2) having the width (W1) is shown in FIG. 3 in the longitudinal direction from the left end (d) to the right end (c) of the glass substrate (1). Middle, parallel to the X-axis direction and at a pitch (P1) in the Y-axis direction.

  FIG. 3 shows that the stripe-shaped red colored pixel pattern (3R) of the first color is normal with no inclination in the opening (4) of the light-shielding pattern (2), and that the green-colored pixel pattern of the second color is striped. (3G) is an example formed with an inclination of an angle θ1 with the glass substrate (1). The red colored pixel pattern (3R) having the width (W2) is normally formed without an inclination of the angle, and the peripheral edge thereof is formed so as to overlap the end of the light shielding pattern (2).

In FIG. 3, the symbol (O) at the right end (c) indicates a photo with an inclination by causing a positional shift so that the photomask rotates in a plane when the green colored pixel pattern (3G) is formed. It represents the center of rotation of the mask. The green colored pixel pattern (3G) formed with the photomask having this inclination (θ1) has a light shielding pattern (2) at the periphery of the green colored pixel pattern (3G) at the right end (c) of the glass substrate (1). ) Are overlapped with the end, but the overlap gradually decreases toward the left end (d), and the green colored pixel pattern (3G) is deviated from the light shielding pattern (2) at the left end (d). This represents a state in which color loss (N1) has occurred.

  In the left end portion (d), the lower end of the second color green pixel pattern (3G) overlaps the upper end of the first color red color pixel pattern (3R) previously formed, and color overlap ( K1) is generated. In FIG. 3, this color overlap (K1) is in the light shielding pattern (2) having the width (W1), and the upper end of the red colored pixel pattern (3R) is caused by the lower end of the green colored pixel pattern (3G). This is a state in which no obvious defects such as mixed colors and turbid display colors have been reached.

  On the other hand, FIG. 4 is an example in which the green color pixel pattern (3G) of the second color is formed with an inclination of the angle θ2 (θ2> θ1) with the glass substrate (1). As shown in FIG. 4, the lower end of the left end portion (d) of the second color green-colored pixel pattern (3G) deviates from the light shielding pattern (2) having the width (W1). In this case, the color overlap (K2) between the upper end of the left end portion (d) of the red color pixel pattern (3R) of the first color formed previously and the lower end of the green color pixel pattern (3G) is an obvious defect. It becomes the state.

As described above, the orientation of the photomask does not become a desired orientation, and the glass substrate and the photomask have an inclination of an angle, thereby causing a positional shift in the colored pixels. As a result, when color loss or color overlap occurs, the color filter substrate has a defect.
Even if the photomask is tilted at a slight angle, for example, in a color filter having a large area with one side exceeding 1 m, the distance between both ends becomes long, and the positional deviation becomes significant. Further, the pixels are miniaturized and the pixel size is several tens of μm or less, and the influence of the positional deviation due to the slight inclination of the angle of the photomask is increasing.

However, in the comparative inspection method described above, adjacent colored pixels are comparatively inspected. Even when color loss or color overlap occurs between adjacent colored pixels, the amount of change is determined to be very small and not the same (not a defect). Therefore, the comparative inspection method cannot detect color loss and color overlap of the color filter substrate having a large area.
Japanese Patent Laid-Open No. 6-18435

  The present invention has been made to solve the above-described problem. When a light-shielding pattern is formed on a glass substrate and subsequently a colored pixel pattern is formed, the colored pixel pattern is planar with respect to the glass substrate. PROBLEM TO BE SOLVED: To provide a color filter inspection method capable of detecting color loss and color overlap caused by a positional shift of a colored pixel pattern on a color filter substrate caused by being formed with a slight angle when viewed. It is what.

According to the present invention, the color filter substrate is transported in the horizontal direction, and the saturation average value of the colored pixel region at one end of the substrate on the color filter substrate is opposed to the substrate end by the imaging device provided in the transport device. that the average saturation value of the color pixel region of the other substrate edge for respectively detected by the imaging device to detect the color loss and color overlapping defects due to positional deviation of the color pixel pattern difference between the average saturation value This is a characteristic color filter inspection method.

In the color filter inspection method according to the present invention, the shape of the colored pixels is not limited to the stripe shape. For example, the color filter may be a color filter in which rectangular colored pixel patterns are arranged in a grid pattern. I do not care.
In the present invention, the information on the pixel region at one end of the color filter substrate and the information on the pixel region at the other end are respectively detected by the imaging device and the information is compared. Therefore, it is possible to detect color omission and color overlap caused by a positional shift of the colored pixel pattern on the color filter substrate, which is caused by pattern exposure of the photomask with a slight angle in plan view with respect to the glass substrate. The color filter inspection method is performed.

  Further, since the information to be detected is the saturation average value obtained from each pixel in the imaging region, it is possible to easily detect color loss on the color filter substrate.

Below, based on the embodiment of the present invention, it explains in detail.
FIGS. 5A and 5B are side views schematically showing an example of the color filter inspection method according to the present invention. As shown by the white arrow in FIG. 5A, the one end portion (c) of the color filter substrate (10) conveyed from the left side in FIG. Information on the pixel area (for example, the average value of the saturation of the shooting area) is detected by the imaging device (12) provided above the transport device (11).

  Next, the color filter substrate (10) is transported by the transport device (11). Next, when the other end (d) of the color filter substrate (10) comes below the imaging device (12), as shown in FIG. 5 (b), the other end of the color filter substrate (10). Information on the pixel region (d) (average value of saturation of the photographing region) is detected by the imaging device (12) above the transport device (11).

  The one end (c) and the other end (d) of the color filter substrate (10) are, for example, as shown in FIG. 3, the right end (c) and the left end ( d), when there is an overlapping portion (K1) and a color loss portion (N1), information on the pixel region of one end (c) and the other end (d) By comparing the pixel area information, it is possible to detect a color loss and a color overlap defect caused by a positional shift of the colored pixel pattern.

  As shown in FIG. 1, the color filter inspection method according to the present invention does not perform a comparative inspection between adjacent pixel regions (5A, 5B), but instead separates pixel regions at both ends on the color filter substrate. Since the comparison is made, for example, it is possible to detect a color loss defect due to the inclination of the angle between the light shielding pattern (2) on the glass substrate and the green colored pixel pattern (3G) in FIG.

In the present invention, the pixel area information obtained by the imaging device (12) is targeted for hue, saturation, brightness, and the like. When this occurs, it is found that the information that fluctuates greatly is the saturation value, and the saturation value is used as the information of the pixel area to be compared.

FIG. 6 is an enlarged plan view of a part of an example of a color filter substrate on which a striped red colored pixel pattern (3R), a green colored pixel pattern (3G), and a blue colored pixel pattern (3B) are formed. is there. FIG. 6 shows three pixel regions (5) for each color.
As the saturation value as information of the pixel region in the present invention, a saturation average value that is an average value of the saturations of the region imaged by the imaging device, for example, all the pixel regions within 5 mmφ is used.

FIG. 7 is an example of a correlation diagram between the color loss width on the color filter substrate and the saturation average value. FIG. 7 is a correlation diagram specifically obtained by experiments.
The blue colored pixel pattern of the color filter substrate on which a striped colored pixel pattern having a width of 100 μm and a length of 300 μm is formed is subjected to pattern exposure by rotating the photomask by 0.5 ° to intentionally shift the position of the colored pixel pattern. It is generated by measuring the width of color loss in each imposition with a microscope and reading the saturation average value in the width of color loss.

By using this correlation diagram, the color loss on the color filter substrate can be easily detected from the saturation average value.
In actual detection, information on the pixel region at one end, that is, the saturation average value at one end, and information on the pixel region at the other end, that is, saturation average value at the other end It is preferable that the defect is detected when the result is out of a preset numerical value.

  In this case, for example, a method of calculating the standard deviation and setting the upper and lower limits by ± 3σ is given as an example of setting the numerical values in advance.

It is a top view of an example of a color filter substrate in which a light shielding pattern and a colored pixel pattern are sequentially formed on a glass substrate. It is sectional drawing in the AA line in FIG. It is a top view which shows an example of the color omission generate | occur | produced in the color filter board | substrate. This is an example in which the second color green pixel pattern is formed with an inclination of the angle θ2 with respect to the glass substrate. (A), (b) is a side view which shows the outline of an example of the inspection method of the color filter by this invention. It is the top view to which one part of an example of the color filter substrate in which the colored pixel pattern of 3 colors was formed was expanded. It is an example of a correlation diagram between the width of color loss on the color filter substrate and the saturation average value.

Explanation of symbols

1 ... Glass substrate 2 ... Shading pattern (black matrix)
3... Colored pixel pattern 3 R... Red colored pixel pattern 3 G... Green colored pixel pattern 3 B... Blue colored pixel pattern 4. .... Color filter substrate 11 ... Conveying device 12 ... Imaging devices N1, N2 ... Color loss K1, K2 ... Color overlap O ... Photomask rotation centers [theta] 1, [theta] 2 ... Photo Mask tilt

Claims (1)

The color filter substrate is transported in the horizontal direction, and the saturation value of the color pixel area at one end of the substrate on the color filter substrate and the other substrate facing the substrate end by the imaging device provided in the transport device A color characterized by detecting an average saturation value of a colored pixel region at an end by an imaging device, and detecting a color omission and a color overlap defect due to a displacement of a colored pixel pattern based on a difference between the respective saturation average values Filter inspection method.

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