JP3714946B2 - Color filter with alignment mark - Google Patents

Description

  The present invention relates to a color filter for a liquid crystal display, and more specifically, in the step of forming a pattern of a light shielding layer and a pattern of colored pixels of red (R), green (G), and blue (B). The present invention relates to a color filter provided with an alignment mark for alignment used when sequentially forming.

The structure of a general color filter used in a liquid crystal display is as shown in the cross-sectional view of FIG. 1. This color filter has a light shielding layer 2 made of a thin film such as chromium on a substrate 1 made of glass or plastic. After the pattern is formed, a pattern of fine colored pixels 3 of a plurality of colors (R, G, B) is repeatedly formed on the pattern, a protective film 4 is further formed thereon, and ITO is formed as the transparent electrode 5. It is made by filming. And as a method of forming the colored pixel 3 in this color filter, there are a dyeing method, a pigment dispersion method, a printing method, an electrodeposition method, a transfer method, etc., and the substrate on which the light shielding layer 2 is formed in any method. It is necessary to align the patterns in the process of sequentially forming the colored pixels 3 on the substrate 1. And, as a means for effectively performing this alignment, the prior art is disclosed in the following patent document, for example, although it is in the field of semiconductors.
JP-A-61-61419 JP-A-56-109350

  In the former, the first and second alignment marks are a combination of a cruciform shape in which the four tops of the rectangle are deleted and a rectangular frame shape having a size surrounding the outer periphery thereof, and pattern alignment workability is achieved. It is intended to improve. In the latter, two sets of pattern groups composed of the same target are formed on the wafer symmetrically to each other and used for mask alignment.

  The alignment method described in the prior art is effective in the manufacturing process of the semiconductor device, but this is a process of sequentially forming the pattern of the light shielding layer and the pattern of each colored pixel in the color filter for the liquid crystal display. The following problems occur when trying to use for pattern matching.

  That is, when the former method is used, the first mark is formed on the color filter substrate simultaneously with the light shielding layer, and the pattern is aligned with the second mark for each color formed on the exposure mask side with respect to the mark. Sometimes, R, G, and B have similar patterns, so the colors to be formed may be mistaken. Furthermore, when the orientation of the color filter substrate is reversed, it can not be determined from just the color filter substrate that the orientation is reversed, as can be seen from the various color filter pattern arrangements shown in FIGS. Of course, there is a risk of mistakes even after the inspection process. The same applies when the mask substrate is set upside down.

  Further, when the latter method is used, the target pattern is formed on the color filter substrate simultaneously with the light shielding layer, and the pattern is aligned with the alignment mark for each color formed on the exposure mask side with respect to the mark. When the exposure mask is used for each color, it is necessary to form marks corresponding to the respective colors together on the mask. In other words, when combined, the rectangular marks formed on the exposure mask are 16 left and right for each color, and 48 marks are required for 3 colors. This results in complicated pattern matching, and an unpractical configuration that invites mistakes.

  Here, when the orientation of the color filter substrate is reversed, since only the first first sheet is visually checked for alignment, the alignment of the color filter substrate can be checked. However, a plurality of color filter substrates are set in the feeder of the color filter manufacturing apparatus, and the second and subsequent sheets are sequentially processed according to the alignment of the first sheet, and alignment by visual confirmation is not performed. If the feeder includes a color filter substrate with the conveyance direction reversed by mistake, the alignment mark may be small, and it may be impossible to determine from the color filter substrate. In particular, during the manufacture of the color filter, it cannot be determined by visually checking the direction of conveyance of the color filter substrate. Of course, there is a risk of mistakes even after the inspection process. This may be considered as a problem common to both methods.

  In addition, as a common problem between the two, when the color filter substrate is set upside down, the color filter substrate is transparent unlike the wafer, and therefore cannot be determined solely from the color filter substrate. Of course, there is a risk of mistakes even after the inspection process. The same applies to the case where the mask substrate is set upside down.

  On the other hand, as a device for indicating the transport direction of the color filter substrate during the manufacture of the color filter, it has been conventionally performed to cut the corners of the color filter substrate, but this method uses a precisely processed glass substrate. There is a possibility that cutting scraps may adhere to the surface, and naturally, it is necessary to increase the number of steps for cutting off the corners of the glass substrate, which is not preferable.

  The present invention has been made in view of the above-described problems. The object of the present invention is to sequentially form a shading layer and R, G, and B colored pixel patterns on a color filter substrate. An object of the present invention is to provide a color filter provided with an alignment mark that can easily and simultaneously check the conveyance direction and front and back errors of the color filter substrate as alignment marks for alignment.

  In order to achieve the above object, the color filter with an alignment mark according to the present invention is a color filter in which an alignment mark for alignment used when superimposing patterns of each colored pixel is attached when forming a light shielding layer. Alignment for each color on both sides of the pattern portion at a position shifted from the center line of the substrate or the pattern portion to the front or rear side of the traveling direction from the center line whose angle with the traveling direction of the substrate is approximately 90 degrees Two sets of alignment mark groups in which the mark arrangement is symmetrical and alignment marks in the same direction are provided.

  In addition, it is desirable that the alignment mark has a “ten” shape. In order to facilitate visual check, it is desirable to form a symbol for identifying each color, for example, an initial of each color, in the vicinity of each alignment mark. .

  The color filter with an alignment mark of the present invention has an alignment mark group at a position shifted from the center line, so that when the color filter substrate is transported in the opposite direction, the alignment mark on the color filter substrate and the mask substrate overlap. In addition, when the color filter substrate is transported upside down, the alignment marks on the color filter substrate and the mask substrate do not overlap, so the pattern of the light shielding layer and the color pixels of the color filter for the liquid crystal display In the process of sequentially forming the pattern, it is possible to easily and simultaneously check the substrate transport direction error and the front / back setting error.

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

  First, the top view which shows the image of the color filter with an alignment mark which concerns on this invention is shown in FIG.

  The color filter substrate 10 has a rectangular shape when viewed from above, and a pattern portion 11 composed of a light shielding layer and R, G, and B colored pixels is provided in the center on the substrate 10 to form a single surface. As described above, the patterns of the colored pixels in the pattern portion 11 have various arrangements as shown in FIGS. The pattern portion 11 is first formed through a light shielding layer pattern forming process, a red colored pixel pattern forming process, a green colored pixel pattern forming process, and a blue colored pixel pattern forming process. Then, alignment mark regions 12 used for alignment in the pattern forming step are provided on both sides of the pattern portion 11 simultaneously with the formation of the light shielding layer. The region 12 is formed so as to be shifted from the center line α, which is the center line of the color filter substrate 10 or the pattern portion 11 and is approximately 90 degrees, to the front or rear side of the traveling direction. Thus, the traveling direction of the color filter substrate 10 is displayed.

  In FIG. 6, the pattern portion 11 of the color filter is single-sided. However, as shown in FIG. For example, there are four facets having pattern portions 11 near the four corners. The color filter substrate 10 includes 320 mm × 300 mm, 400 mm × 300 mm, and the like, and has a thickness of 1.1 mm.

  Next, a specific example of the color filter with alignment marks according to the present invention is shown in FIG.

  The color filter substrate 10 in FIG. 8 is a rectangle having a size of 350 mm × 300 mm when viewed from above, a thickness of 0.7 mm, and a material thereof is glass. A pattern portion 11 is provided in the center on the substrate 10 to form a single surface, and the center line of the color filter substrate 10 and the center line (lateral direction) of the pattern portion 11 are the same. In addition, the pattern of each coloring pixel is an interval of 100 μm. The color filter substrate 10 is provided with two sets of alignment mark groups in which the alignment marks for each color are symmetrical and alignment marks in the same direction on both sides of the pattern portion 11 as shown in the figure. ing. A more detailed description will be given below with reference to FIG. 9 showing an alignment mark group in which the alignment marks for each color are symmetrical among the two sets of alignment mark groups.

  In the color filter substrate 10 of FIG. 9, alignment mark regions 12 (generally 6 mm × 6 mm) for arranging alignment marks made of the same material as the light shielding layer are provided on both sides of the pattern portion 11, and these are divided into three in the vertical direction. The first region 12a, the second region 12b, and the third region 12c (each approximately 6 mm × 2 mm). The alignment mark region 12 is the center line of the color filter substrate 10 and the pattern portion 11, and the direction of travel (in the direction of the arrow in the figure) from the center line α that is approximately 90 degrees with the direction of travel of the substrate 10. ) Are formed to be shifted to the front side. Then, alignment marks made of the same material as the light shielding layer are formed in a “ten” shape in each of the three divided regions 12a to 12c. Here, a red alignment mark is disposed below the first region 12a, a green alignment mark is disposed at the center of the second region 12b, and a blue alignment mark is disposed above the third region 12c. Thus, as shown, the alignment marks are symmetric. The line width of the vertical and horizontal lines of this “ten” mark is 50 μm and the length is 1.5 mm. In addition, symbols “R”, “G”, and “B” are provided in the vicinity of these marks in order to indicate how many alignment marks are used for alignment of colored pixel patterns. The light shielding layer is called a black matrix and is mainly formed of chromium, and the mark “ten” is also formed of chromium at the same time. The thickness of this chromium layer is usually 0.05-0.20 μm.

  Next, an exposure mask substrate for pattern transfer used in the process of forming a colored pixel pattern on the color filter substrate 10 will be described. FIG. 10 is an explanatory view showing an exposure mask substrate corresponding to the color filter substrate of FIG.

  As shown in FIG. 10, a pattern portion 21 is provided on the mask substrate 20 in the vertical direction, and alignment mark regions 22 are provided on both sides thereof. In the alignment mark region 22, a “well” -shaped alignment mark is formed so as to correspond to the alignment mark “ten” formed on the color filter substrate 10 of FIG. 9. That is, a red mark “well” is arranged for the first color under the first area 22a of the three-segment alignment mark area 22, and the green for the second color is arranged in the center of the second area 22b. A mark “well” is arranged, and a blue mark “well” is arranged for the third color above the third region 22c. This mark has a line width of 50 μm, and the closed loop “□” in the mark is formed to be 800 μm vertically and horizontally. Further, symbols “R”, “G”, and “B” corresponding to the respective colors are provided in the vicinity of each mark “well”. These symbols may be formed so as to be confirmed side by side with the symbols on the color filter substrate when alignment is performed, or may be overlapped.

  Further, if the length of one vertical side and the length of one horizontal side of the closed loop “□” in each mark “well” is set as an allowable alignment value, the crossing portion of the mark “ten” on the color filter substrate 10 is set. Whether or not the alignment is good can be confirmed based on whether or not it exists in the “□”. The allowable value is about ± 30 μm, but is preferably less than that. For this purpose, it is necessary to further reduce the line width. When the vertical and horizontal allowable values have different allowable values depending on the color filter, the “□” portion inside each mark “well” is rectangular.

  In this way, the R, G, B color mark “well” on the mask substrate 20 and the mark “ten” on the color filter substrate 10 corresponding to each color of the alignment mark regions 12, 22 divided into three, respectively. Since the upper portions of the first regions 12a and 22a, the central portions of the second regions 12b and 22b, and the lower portions of the third regions 12c and 22c are formed so as to overlap each other, the colors of R, G, and B It is easy to check for errors such as omissions and replacements, making visual inspection easier. Further, the efficiency of visual confirmation is improved by providing symbols “R”, “G”, and “B” corresponding to the respective colors in the vicinity of the R, G, and B color marks “well”.

  The R, G, B color mark “well” used for the color filter substrate 10 and the mask substrate 20 may be a mark “□”. Further, other symbols in place of the symbols “R”, “G”, and “B” corresponding to the respective colors may be used in the vicinity of the marks “I” and “□” of these colors. Of course, it is sufficient that the symbols at this time can be easily recognized at the time of visual confirmation.

  Next, a manufacturing method of a color filter using the present invention will be described with reference to the process chart of FIG. As described above, the color filter manufacturing method includes a dyeing method, a pigment dispersion method, a printing method, an electrodeposition method, a transfer method, and the like. The color filter substrate with an alignment mark of the present invention is used for all of these manufacturing methods. However, here, the manufacturing process by the pigment dispersion method will be described as an example.

  First, in step 1, the glass substrate is cleaned. Next, after forming a chromium film in step 2, a chromium thin film is processed in step 3 to form a light shielding layer pattern. At this time, three alignment marks are processed. The shape is “ten”, and alignment marks are respectively arranged in the lower part of the first region 12a, the center of the second region 12b, and the upper part of the third region 12c of the alignment mark region 12 divided into three. Pattern processing itself is a normal method. As a result, the color filter substrate 10 shown in FIG. 8 having only the light shielding layer formed on the pattern portion is completed. That is, a substrate excluding the pattern formed by the R, G, and B colored pixels 3 is completed.

  Subsequently, a red (first color) colored resist is applied in Step 4 and prebaked in Step 5 to evaporate only the solvent. Then, after alignment in step 6, exposure is performed in step 7. At this time, the pattern portion 11 is exposed to the first color pattern and, at the same time, the alignment mark “well” and the symbol “R” provided on both sides of the pattern portion 11 are masked so as not to be exposed. This is because accurate alignment cannot be performed when other colored patterns are formed unless this masking process is performed.

  The alignment in step 6 will be described with reference to FIG. A mask substrate 20 shown in FIG. 10 is overlaid on the color filter substrate 10 with an interval of 50 μm therebetween so that the respective alignment marks overlap. Each of these substrates 10 and 20 is supported by a holder (not shown). A CCD camera 6 having an area sensor of about 250,000 pixels and two light sources 7 and 7 are installed above the alignment mark regions 12 and 22 so that the alignment mark can be monitored. First, the camera 6 performs general alignment by photographing an area of 6 mm × 6 mm (area of 144 μm × 144 μm per pixel) that is the alignment mark regions 12 and 22. That is, the holders of the substrates 10 and 20 are moved and adjusted so that three sets of “ten” and “well” alignment marks overlap, and the alignment mark regions 12 and 22 are overlapped. Next, the camera captures an area of 5 μm × 5 μm per pixel by capturing a set of “ten” and “well” alignment marks, and moves and adjusts the holder to perform precise alignment. For high-resolution and high-precision alignment, or when reducing the line width and mark size, use a sensor with a large number of pixels in the area sensor or use a CCD camera with multiple area sensors. do it. Of course, the image memory and the like need to be increased according to these data.

  Subsequently, in step 8, these are developed to remove the pattern of unnecessary areas that are not exposed. In step 9, the exposed pattern is hardened by post-baking.

  Further, the above steps 4 to 9 are repeated by using a colored resist of green as the second color and blue as the third color. Here, the second color mark is arranged in the center of the second region of the alignment mark region in the second color formation step, and the second color mark is arranged above the third region of the alignment mark region in the third color formation step. A third color mark is arranged.

  Here, the alignment performed in step 6 will be described in detail, but will be described first with reference to FIGS. 2 to 5 and then with reference to FIG.

  As can be seen from the pattern arrangement diagrams of the various color filters shown in FIGS. 2 to 5, in the patterns of FIGS. 2 to 4, the R, G, and B colors are each formed by two colored pixels in the horizontal direction and larger. By using this, it is possible to use a single mask substrate for exposure. In addition, since the G pattern cannot be used in the pattern of FIG. 5, it is necessary to prepare separately as shown in FIG. 13, but the R and B patterns are formed larger by one colored pixel in the vertical and horizontal directions. What is necessary is just to use the mask substrate which was made. By forming in this way, the number of exposure masks can be reduced.

  Regarding alignment in step 6, first, an alignment mark group in which the alignment marks for each color are symmetrical will be described. FIGS. 14A and 14B are enlarged views of the overlapped alignment mark region. This is an explanatory diagram for explaining the alignment of the second color G alignment mark. FIG. 14A shows the left alignment mark region of the pattern portion 11, and FIG. 14B shows the right alignment mark region. Of the “ten” -shaped alignment marks formed on the color filter substrate 10, the mark at the center of the second color is formed on the exposure mask substrate 20 for both R, G, and B colors. Align the mark in the center of a certain "well" -shaped alignment mark. If normal, the alignment marks for the other colors are shifted by ± 1 color pixel. If the color filter substrate 10 is transported in the wrong direction, the alignment mark “10” (color filter substrate) is reversed because the angle formed with the substrate traveling direction is reversed at the center line of the color filter substrate which is approximately 90 degrees. ) And “I” (mask substrate) do not overlap at all. Even if they are moved very much and overlapped, only the alignment mark for G overlaps, and a mark group is formed in an “x” shape in the alignment mark region with this as an intersection. FIG. 15A shows the left alignment mark region of the pattern portion 11 and FIG. 15B also shows the right alignment mark region as an “x” -shaped image of the alignment mark group when this defect occurs. Yes. In any case, it is possible to recognize that the setting of the color filter substrate 10 is defective.

  Next, an alignment mark group in which the alignment marks for the respective colors are in the same direction will be described. FIG. 16A shows the left alignment mark region of the pattern portion 11, and FIG. 16B shows the right alignment mark region. Of the “ten” -shaped alignment marks formed on the color filter substrate 10, the mark at the center of the second color is formed on the exposure mask substrate 20 for both R, G, and B colors. Align the mark in the center of a certain "well" -shaped alignment mark. If normal, the alignment marks for the other colors are shifted by ± 1 color pixel. If the color filter substrate 10 is turned upside down, only the alignment mark “10” for G (color filter substrate) and “well” (mask substrate) overlap, and this is the intersection and “×” A mark group is formed in a "" shape. FIG. 17A shows the left alignment mark region of the pattern portion, and FIG. 17B also shows the right alignment mark region as an “x” -shaped image of the alignment mark group when this defect occurs. Thereby, it can be recognized that the setting of the substrate is defective.

  Here, in FIG. 14 and FIG. 16, when the shift amounts of the left and right alignment marks are different, there is a cause that the glass substrate is twisted. Therefore, the movement adjustment of the holder of each substrate is performed. Of course, the same applies to the first R and the third B.

  After completing the coloring of the third color, an overcoat layer is provided to cover the colored pixels in Step 10 to form a protective film, and then a transparent conductive layer is formed in Step 11.

It is sectional drawing which shows the structure of a general color filter. It is a pattern arrangement | positioning figure of each coloring pixel in a color filter. It is another pattern arrangement | positioning figure similarly. It is another pattern arrangement | positioning figure similarly. It is another pattern arrangement | positioning figure similarly. It is a top view which shows the image of the color filter with an alignment mark as one Example of this invention. It is explanatory drawing which shows the other example of imposition of a color filter. It is a top view which shows a specific example of the color filter with an alignment mark which concerns on this invention. It is explanatory drawing which shows the alignment mark group with which the alignment mark alignment for each color is symmetrical. It is explanatory drawing which shows the mask substrate for exposure corresponding to the color filter substrate of FIG. It is a figure which shows the manufacturing process of a color filter. It is explanatory drawing which shows the alignment method of a color filter board | substrate and a mask board | substrate. It is explanatory drawing which shows the mask substrate for exposure of the pattern for green. It is usage explanatory drawing of the alignment mark group with which the alignment mark alignment for each color is symmetrical. It is explanatory drawing of the alignment mark at the time of the defect generation | occurrence | production in the case of using the alignment mark group where the alignment mark alignment for each color is symmetrical. It is usage explanatory drawing of the alignment mark group in which the alignment mark for each color has the same direction. It is explanatory drawing of the alignment mark at the time of the defect generation | occurrence | production in case the alignment mark group of the alignment mark for each color uses the same direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Color filter board | substrate 11 Pattern part 12 Alignment mark area | region 12a 1st area | region 12b 2nd area | region 12c 3rd area | region (alpha) Center line

Claims (4)

  In the color filter in which the alignment mark for alignment used when superimposing the pattern of each colored pixel is attached when forming the light shielding layer, the angle formed between the color filter substrate or the center line of the pattern portion and the traveling direction of the substrate is An alignment mark group in which the alignment mark alignment lines for each color are symmetrical and an alignment mark group in the same direction on both sides of the pattern portion at a position deviated from the center line of approximately 90 degrees to the front or rear side in the traveling direction. A color filter with an alignment mark, characterized in that two sets are provided.   The color filter with an alignment mark according to claim 1, wherein the alignment mark has a "ten" shape.   3. The color filter with an alignment mark according to claim 1, wherein a symbol for identifying each color is formed in the vicinity of each alignment mark. 4. The color filter with an alignment mark according to claim 3, wherein a symbol for identifying each color is an initial of each color.

Images