JP2007272222A - Color filter and photo mask used for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color filter which prepares two kinds of photo spacers having different heights at one time exposure by using the same mask and has high pressurizing endurance, and also to provide a photo mask used for manufacturing the color filter. <P>SOLUTION: The color filter has a first photo spacer and a second photo spacer having a thickness smaller than that of the first photo spacer, wherein the second spacer has such a cross-section shape that the longitudinal width is longer than the lateral width. The photo spacer of the color filter has a first opening pattern for forming the first photo spacer and a second opening pattern for forming the second photo spacer having a film thickness smaller than that of the first photo spacer, wherein the second opening pattern is manufactured by using a photo mask having such a shape that the lateral width is within 2.0 μm to 10.0 μm and the ratio of the lateral width to the longitudinal width is at least 1:1.25. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

 The present invention relates to a color filter for a liquid crystal display device and a photomask used for the manufacturing method thereof, and more particularly to a color filter for a liquid crystal display device having two types of photo spacers having different thicknesses.

 For example, as shown in FIG. 7, the color filter used in the liquid crystal display device is formed by sequentially forming a black matrix 71, a colored pixel 72, and a transparent conductive film 73 on a glass substrate 70. A color filter having such a structure is formed by first forming a black matrix on a glass substrate, then forming a colored pixel by aligning with the pattern of the black matrix, and further aligning a transparent conductive film. It is formed.

 With the development and commercialization of various liquid crystal display devices, color filters used in liquid crystal display devices are accompanied by the above basic functions, for example: 1) protective layer (overcoat layer), 2) semi-transmission 3) Light path adjustment layer for aligning the phase of light passing through the transmissive display area and the reflective display area, and 4) the light to the reflective display area of the color filter. Members having various functions such as a scattering layer, 5) a photo spacer having a spacer function, and 6) an alignment control protrusion for controlling the alignment of liquid crystal are added based on the use and specifications of the color filter. became.

 In particular, in order to provide a spacer function, in a conventional liquid crystal display device, transparent spherical particles (beads) or short fibers of glass or synthetic resin called spacers are dispersed to form a gap between substrates.

 However, since these spacers are transparent particles, if there is a liquid crystal and a spacer in the pixel, light will leak through the spacer during black display, and the liquid crystal material will be sealed. Due to the presence of spacers between the substrates, the alignment of liquid crystal molecules in the vicinity of the spacers is disturbed, causing light leakage at this part, reducing the contrast, and adversely affecting the display quality. It was.

 As a technique for solving such a problem, for example, a technique has been developed in which a photosensitive resin is used at the position of the black matrix between pixels and a protrusion having a spacer function (hereinafter referred to as a photo spacer) is formed by photolithography. It was done.

 FIG. 8 is a partial cross-sectional view of such a color filter for a liquid crystal display device. As shown in FIG. 8, in the color filter 87 for the liquid crystal display device, a black matrix 81, a colored pixel 82, and a transparent conductive film 83 are sequentially formed on a glass substrate 80, and on the transparent conductive film 83 above the black matrix 81. A photospacer 84 is formed as a protrusion having a spacer function. In the liquid crystal display device using such a color filter 87 for filling the liquid crystal display, the photo spacer 84 can be formed at a position avoiding the inside of the colored pixels, so that the improvement of the contrast of the liquid crystal display is observed.

 In a panel assembling process for attaching a color filter for a liquid crystal display device and a counter substrate to form a liquid crystal display panel, a seal portion (not shown) is provided in the peripheral portion, a load is applied between the upper and lower surface plates, and the seal portion and the photo spacer 84 are provided. The photo spacer undergoes some elastic deformation due to the load applied at this time, and the gap between the substrates is set in this deformed state.

 As described above, the gap between the substrates is set by the photo spacer, but the deformation of the photo spacer when a normal load is applied to the panel is reduced, and the photo spacer when the excessive load is applied is reduced. It is necessary to prevent plastic deformation and fracture.

 A color filter for a liquid crystal display device provided with two types of photo spacers has been proposed as a technique for coping with problems such as plastic deformation and breakage due to excessive load. FIG. 9 is a cross-sectional view schematically showing an example of a color filter for a liquid crystal display device having two types of photo spacers having different heights. As shown in FIG. 9, this color filter for a liquid crystal display device is composed of a main photo spacer 84a having a high height and a sub photo spacer 84b having a low height as a photo spacer in the structural color filter shown in FIG. It is a thing.

 Of these two types of photo spacers, the main photo spacer 84a sets a gap between the substrates. The main photo spacer 84a is deformed when a load is applied to the panel, and is restored when the load is removed. Moreover, it has the elasticity which deform | transforms following the thermal expansion and thermal contraction of the liquid crystal with temperature.

 The sub photospacer 84b is a photospacer having a height lower than that of the main photospacer 84a, and is used to prevent plastic deformation and destruction of the main photospacer 84a by dispersing the load when an excessive load is applied to the panel. It is.

 As a method of forming main photo spacers and sub photo spacers with different heights, a photomask with the same shape as the main photo spacers, the mask opening size is made smaller than the main photo spacers, and the amount of light transmitted is controlled. In addition, there is a method of forming a photo spacer having a low height.

 However, according to such a method, since the sub-photo spacer is formed by reducing the light transmission amount by reducing the photomask opening size, not only the height but also the size of the sub-photo spacer 84b is the main size. It must be smaller than the size of the photo spacer 84a. When the size of the sub photo spacer 84b is small, the pressure resistance is lowered. In order to increase the pressure resistance, it is necessary to increase the density (number per unit area) of the photo spacer, but there is a limit to this. In addition, since the sub-photo spacer with a small size is easily peeled off during manufacture, it cannot be produced unless production conditions are strictly controlled.

Also, as a method of forming two types of photo spacers with different heights, a method of forming a sub photo spacer by controlling the amount of exposure light transmitted by halftone processing and gray tone processing on a photomask is known. However, these require high accuracy during complicated photomask processing and processing.
U.S. Pat. No. 3,846,264

 The present invention has been made under the circumstances as described above, and can produce two kinds of photo spacers having different heights by using the same mask and can be produced by one exposure, and a color filter having high pressure resistance, and its manufacture. An object of the present invention is to provide a photomask for use in the above.

 In order to solve the above-described problem, a first aspect of the present invention is a color filter having a first photo spacer and a second photo spacer having a thickness smaller than that of the first photo spacer. The photo spacer of the present invention provides a color filter characterized in that the photo spacer has a cross-sectional shape having a longitudinal length longer than its lateral width.

 In such a color filter, it is preferable that the second photo spacer has a cross-sectional shape whose vertical width is 1.25 times or more with respect to the horizontal width. The second photo spacer preferably has a cross-sectional shape selected from the group consisting of a rectangle, an ellipse, an oval, and a pincushion.

Furthermore, the second photo spacer may have a characteristic shape in which the top surface has two raised portions at both ends in the longitudinal direction.

 Furthermore, the difference in film thickness between the first photo spacer and the second photo spacer is preferably 0.1 μm to 1.0 μm. In addition, it is desirable that the second photo spacer is disposed above the black matrix.

 According to a second aspect of the present invention, a first opening pattern for forming a first photospacer and a second opening pattern for forming a second photospacer having a smaller film thickness than the first photospacer are provided. The second opening pattern has a shape in which the width is in the range of 2.0 μm to 10.0 μm, and the ratio of width to length is 1: 1.25 or more. Provided is a photomask for manufacturing a color spacer photospacer.

 Moreover, it is preferable that the diameter of the first opening pattern is larger than the width of the second opening pattern.

 In the photomask for manufacturing such a photospacer, the second opening pattern preferably has a lateral width of 3.0 μm to 5.0 μm. In other words, the first opening pattern preferably has an opening width of 8 to 20 μm.

 A third aspect of the present invention includes a first photo spacer and a second photo spacer having a film thickness smaller than that of the first photo spacer. In the color filter having a cross-sectional shape with a long vertical length, the first photo spacer and the second photo spacer are exposed to the photosensitive composition layer through the above-described photomask, thereby performing one exposure. And a color filter produced by one development operation.

 According to the present invention, a sub-photo spacer having a height lower than that of the main photo spacer is made simultaneously with the main photo spacer by one exposure operation with one photo mask by shortening the width of the photo mask of the sub photo spacer. it can.

 Also, by increasing the vertical width of the photomask of the sub-photo spacer, a sub-photo spacer having the same size as the main photo spacer or larger than the main photo spacer is formed by one exposure with one photo mask. can do.

 Therefore, a sub-photo spacer with a large area size can be formed, so that a color filter with high pressure resistance can be provided, and a sub-photo spacer with a large size can be formed, making it easy to control production conditions and improving productivity. Can be made.

 Further, the shape of the opening pattern for the sub-photo spacer of the photomask to be used may be rectangular, and no hearton processing or the like is required. Therefore, the photomask processing is simple and productive patterning is possible.

 The best mode for carrying out the invention will be described below.

 FIG. 1 is a schematic diagram showing a local arrangement example of photo spacers according to an embodiment of the present invention. In FIG. 1, a first photo spacer (main photo spacer) 12 having a height a on a substrate (for example, a transparent conductive film) 11, and a first photo spacer having a height b lower than the main photo spacer 12. Two photo spacers (sub photo spacers) 13 are provided adjacent to each other.

In these cross-sectional shapes, the ratio of the width (minor axis) c to the length (major axis) d is preferably not less than width: length = 1: 1.25. When the vertical width is smaller than this range, it is not preferable because the area of the second photo spacer becomes insufficient when viewed from above, and the pressure resistance tends to be weakened.

 In this example, the main photospacer 12 has a cylindrical shape, whereas the sub-photospacer 13 has a shape having two raised portions at both ends of the upper surface of the rectangular parallelepiped, that is, a vertical shape having a bumpy convex portion at both ends of the upper side of the rectangle. It has a cross-sectional shape. The vertical cross-sectional shape mentioned here means a cross-sectional shape when cut perpendicularly to the substrate 11.

 The horizontal cross-sectional shape of the sub-photo spacer 13 may be any shape as long as it is substantially rectangular. For example, as such a shape, an elliptical shape shown in FIG. 2 (a), an oval shape shown in FIG. 2 (b), a pincushion shape shown in FIG. 2 (c), and a substantially rectangular shape shown in FIG. 2 (d). Is mentioned.

 The difference in film thickness between the main photo spacer 12 and the sub photo spacer 13 is preferably 0.1 μm to 1.0 μm. If the difference in film thickness is less than 0.1 μm, the low-temperature resistance of the LCD panel is deteriorated, and if it exceeds 1.0 μm, it is difficult to improve the pressing characteristics of the LCD panel.

 Here, an example of the exposure conditions of the photo spacer that can be used in one embodiment of the present invention will be described.

Exposure method: Broximity (proximity) exposure Proximity exposure gap (G): 150 μm ± 50 μm
Exposure amount: 100 mJ / cm ^{2 to} 200 mJ / cm ²
Exposure wavelength: 365nm
Resin Composition: Negative Photosensitive Resin Composition In order to form such a main photospacer 12, the opening width W1 of the photomask pattern for producing the main spacer shown in FIG. 4A is set to 8 to 20 μm. It is desirable. This is because, in the case of an octagonal opening pattern as shown in FIG. 4, if the width W1 is smaller than 8 μm, the transmission intensity of exposure is too small to reach the saturation sensitivity of the photosensitive resin composition. This is because patterning is difficult.

 In order to form the sub-photo spacer 13 having a film thickness difference of 0.1 to 1.0 μm with the main photo spacer 12 formed as described above, the sub-photo spacer is manufactured as shown in FIG. The photomask pattern must have a width W2 in the range of 2.0 μm to 10.0 μm and a shape of the sub-photo spacer 13 such that the ratio of width W2: length W3 is 1: 1.25 or more. is there. In particular, the lateral width W2 is desirably 3.0 μm to 5.0 μm.

 If the width W2 is smaller than 2 μm, the transmission intensity of exposure is too small to reach the saturation sensitivity of the photosensitive resin composition, and thus patterning becomes difficult. Further, when the ratio of the width W2 to the width W3 is less than 1: 1.25, the light transmitted through the photomask is condensed at one place during exposure, so that the transmission intensity increases. Although the film thickness cannot be reduced, the width W2 is set to 3.0 to 5.0 μm, and the ratio of width W2: length W3 is set to 1: 1.25 or more, so that the photomask can be transmitted when exposed. Since the transmitted light is divided into two and the transmission intensity is reduced, a thin sub-photo spacer can be formed.

 The difference in film thickness between the main photospacer 12 and the subphotospacer 13 makes the opening width for forming the subphotospacer 13 of the photomask smaller than the opening width for forming the main photospacer 12, and the amount of transmitted light. Can be achieved by reducing. However, if the opening width is simply reduced, the area size of the horizontal cross section of the formed sub-photo spacer 13 is reduced, and the pressure resistance is reduced.

 The present inventors have made the opening for forming the sub-photo spacer 13 of the photomask narrow in the horizontal direction and long in the vertical direction, so that the light condensing part is divided into two parts to disperse the light. By controlling the transmission intensity, the film thickness of the sub-photo spacer 13 formed by exposure and development through the opening to the photosensitive resin composition can be reduced, and the area size is equal to or larger than that of the main photo spacer. It was found that a sub-photo spacer can be created.

 EXAMPLES Hereinafter, the Example and comparative example of this invention are shown, and this invention is demonstrated more concretely.

Example 1
A method of manufacturing a color filter having main photo spacers 12 and 51 and sub photo spacers 13 and 52 as shown in FIGS. 1 and 5 will be described with reference to FIG.

 As shown in FIG. 3, a photoresist layer 30 is formed on a glass substrate 20 on which a black matrix 21, a colored pixel 22, and a transparent conductive film 23 are sequentially formed, and a gap (G) for proximity exposure is formed thereon. And a photomask 40 for manufacturing a color filter photospacer is disposed.

 In the photomask 40, openings 41 and 42 corresponding to the formation of the main photospacer and the subphotospacer are formed. An example of the shape of the opening 41 is shown in FIG. 4A, and an example of the shape of the opening 42 is shown in FIG. 4B. As shown in FIG. 4A, the opening 41 is octagonal, and as shown in FIG. 4B, the opening 42 is rectangular.

 The film surface of the photomask 40 faces the photoresist layer 30. The photoresist 30 used in this example was a negative photosensitive resin “NN777 (trade name, manufactured by JSR Corporation)”.

In the photomask 40, the width W1 of the opening 41 corresponding to the main photospacer is set to 10 μm, while the width W2 of the opening 42 corresponding to the sub-photospacer having a lower height than the main photospacer is set to 3.0 μm and the vertical width W3. Was 20 μm. This is to reduce the transmission intensity by narrowing the width of the pattern (aperture) and dispersing the condensing part into two to form a photo spacer with a low height.

 The exposure of the photoresist layer 30 through the photomask 40 was performed by the proximity (proximity) exposure method under the following conditions.

Proximity exposure gap (G): 150 μm ± 50 μm
Exposure amount: 100 mJ / cm ^{2 to} 200 mJ / cm ²
Exposure wavelength: 365nm
The photoresist layer 30 exposed under the above conditions was then developed with an alkaline aqueous solution, and as shown in FIG. 5, a main photo spacer 51 and a sub photo spacer 52 were formed on the transparent conductive film surface on the black matrix. .

 In this case, in the opening 41 corresponding to the main photo spacer having the width W1, if there is a sufficient gap (G) of the proximity exposure, the surface of the photoresist layer 40 is approximately formed by diffraction at the opening end of the irradiated light. As a result, a main photo spacer 51 having a circular cross section was formed.

 On the other hand, in the opening 42 corresponding to the sub-photo spacer having the horizontal width W2 and the vertical width W3, the irradiated light is condensed and divided into two rectangular corners, so that the transmission intensity is reduced and the height is low. A sub-photo spacer 52 was formed. The shape of the sub-photo spacer 52 was a shape having two raised portions at both ends of the upper surface of the rectangular parallelepiped as shown in FIG.

 The main photo spacer 51 formed at this time has a height of 4.65 μm, the sub photo spacer 52 has a height of 4.12 μm, and the difference in height between the main photo spacer 51 and the sub photo spacer 52 is 0.53 μm. became.

Example 2
The width W1 of the opening 41 corresponding to the main photo spacer is 15 μm, the horizontal width W2 of the opening 42 corresponding to the sub photo spacer is 8.0 μm, and the vertical width W3 is 10.0 μm, that is, the horizontal width W2: the vertical width W3 = 1: 1. Photo spacers were formed in the same manner as in Example 1 using a photo mask of .25. The height a of the formed main photo spacer 51 is 4.603 μm, the height b of the sub photo spacer 52 is 4.12 μm, and the difference in height between the main photo spacer 51 and the sub photo spacer 52 is 0.48 μm. It was.

Example 3
The width W1 of the opening 41 corresponding to the main photo spacer is 10 μm, the horizontal width W2 of the opening 42 corresponding to the sub photo spacer is 5.0 μm, and the vertical width W3 is 15.0 μm, that is, horizontal width W2: vertical width W3 = 1: 3. A photospacer was formed in the same manner as in Example 1 using the photomask. The height a of the formed main photo spacer 51 is 4.654 μm, the height b of the sub photo spacer 52 is 4.496 μm, and the difference in height between the main photo spacer 51 and the sub photo spacer 52 is 0.16 μm. It was.

Example 4
The width W1 of the opening 41 corresponding to the main photo spacer is 10 μm, the horizontal width W2 of the opening 42 corresponding to the sub photo spacer is 2.5 μm, and the vertical width W3 is 20.0 μm, that is, horizontal width W2: vertical width W3 = 1: 8. A photospacer was formed in the same manner as in Example 1 using the photomask. The height a of the formed main photo spacer 51 is 4.654 μm, the height b of the sub photo spacer 52 is 3.727 μm, and the difference in height between the main photo spacer 51 and the sub photo spacer 52 is 0.93 μm. It was.

Comparative Example 1
The width W1 of the opening 41 corresponding to the main photo spacer is 10 μm, the horizontal width W2 of the opening 42 corresponding to the sub photo spacer is 1.0 μm, and the vertical width W3 is 20.0 μm, that is, the horizontal width W2: the vertical width W3 = 1: 8. A photo spacer was formed in the same manner as in Example 1 using the photo mask. As a result, the main photo spacer could be formed, but the sub photo spacer could not be formed.

 This is presumably because the value of W2 of the sub-photo spacer is too small, the transmitted light of the mask is too small, the exposure amount necessary for forming the sub-photo spacer cannot be obtained, and it is peeled off in the production process.

Comparative Example 2
The width W1 of the opening 41 corresponding to the main photo spacer is 10 μm, the horizontal width W2 of the opening 42 corresponding to the sub photo spacer is 8.7 μm, and the vertical width W3 is 10.0 μm, that is, the horizontal width W2: the vertical width W3 = 1: 1. Photo spacers were formed in the same manner as in Example 1 using a photo mask of .15.

 The height a of the formed main photo spacer is 4.654 μm, the height b of the sub photo spacer is 4.604 μm, and the difference in height between the main photo spacer and the sub photo spacer is 0.05 μm. Couldn't get.

The results of Examples 1 to 4 and Comparative Examples 1 and 2 are summarized in the following table.

 In the embodiments and examples described above, the main photo spacer 51 is located above the black matrix 21, but the photo spacer is present when the elongated sub photo spacer 52 is located above the black matrix 21. It is possible to prevent a decrease in contrast due to.

 FIG. 6 shows an example of a color filter in which a main photo spacer and a sub photo spacer are arranged. In this color filter 60, as shown in FIG. 6, a main photo spacer 61 having a circular cross section and a sub photo spacer 62 having an elongated rectangular cross section are regularly arranged.

FIG. 3 is an explanatory perspective view illustrating an example of a photo spacer in an embodiment of the color filter of the present invention. Explanatory drawing which shows the various examples of the horizontal cross-sectional shape of a subphotospacer. Explanatory drawing which shows the exposure method for forming a main photo spacer and a sub photo spacer. The enlarged plan view which shows the shape of the opening corresponding to formation of the main photo spacer and each sub photo spacer of a photomask. Sectional drawing which shows the color filter which has the main photo spacer and sub photo spacer formed by the exposure method shown in FIG. The top view which shows an example of the color filter by which the main photo spacer and the sub photo spacer are arrange | positioned. Sectional drawing which shows the conventional color filter. Sectional drawing which shows the conventional color filter which has a photospacer. Sectional drawing which shows the conventional color filter which has two types of photo spacers from which thickness differs.

Explanation of symbols

 DESCRIPTION OF SYMBOLS 11 ... Base | substrate, 12, 51, 61 ... Main photo spacer, 13, 52, 62 ... Sub photo spacer, 20 ... Glass substrate, 21 ... Black matrix, 22 ... Colored pixel, 23 ... Transparent electrically conductive film, 30 ... Photoresist layer 40 ... Photomask, 41 ... Opening corresponding to formation of main photospacer, 42 ... Opening corresponding to formation of sub-photospacer.

Claims (11)

 In a color filter having a first photo spacer and a second photo spacer having a film thickness smaller than that of the first photo spacer, the second photo spacer has a length that is longer than a width of the second photo spacer. A color filter having a long cross-sectional shape.  The color filter according to claim 1, wherein the second photo spacer has a cross-sectional shape having a vertical width of 1.25 times or more with respect to a horizontal width.  The color filter according to claim 1 or 2, wherein the second photo spacer has a cross-sectional shape selected from the group consisting of a rectangle, an ellipse, an oval, and a pincushion.  The color filter according to claim 1, wherein an upper surface of the second photo spacer has two raised portions at both ends in the longitudinal direction.  The color filter according to claim 1, wherein a difference in film thickness between the first photo spacer and the second photo spacer is 0.1 μm to 1.0 μm.  The color filter according to claim 1, wherein the second photo spacer is disposed above the black matrix.  In a photomask having a first opening pattern for forming a first photospacer and a second opening pattern for forming a second photospacer having a smaller film thickness than the first photospacer, the second The aperture pattern has a shape in which the width is in the range of 2.0 μm to 10.0 μm and the ratio of width to length is 1: 1.25 or more. Photo mask.  8. The photomask for manufacturing a color filter photospacer according to claim 7, wherein the first opening pattern is circular and the diameter thereof is larger than the horizontal width of the second opening pattern. 9.  9. The photomask for manufacturing a color filter photospacer according to claim 7, wherein the second opening pattern has a lateral width of 3.0 μm to 5.0 μm.  The photomask for manufacturing a color filter photospacer according to claim 7, wherein the first opening pattern has an opening width of 8 to 20 μm.  A cross section having a first photo spacer and a second photo spacer having a film thickness smaller than that of the first photo spacer, wherein the second photo spacer has a length that is longer than a width of the first photo spacer. In the color filter having a shape, the first photo spacer and the second photo spacer are exposed to the photosensitive composition layer through the photomask according to any one of claims 7 to 10, thereby performing one exposure. And a color filter created by one development operation.

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