JP2008281594A - Liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of suppressing plastic deformation of a spacer while suppressing dispersion of a cell gap. <P>SOLUTION: The liquid crystal display is provided with a driving substrate 19 and a counter substrate 10 which are opposed to each other sandwiching a liquid crystal layer and a plurality of spacers 17 and 18 disposed in the liquid crystal layer. A color layer 13 formed on the counter substrate 10 has a first part having a prescribed film thickness and a color layer 14 formed on the counter substrate 10 has a second part having a film thickness thinner than the prescribed film thickness. The plurality of spacers 17 and 18 include the spacer 17 disposed at a surface part of the counter substrate 10 on which the first part is formed and the spacer 18 disposed at a surface part of the counter substrate 10 on which the second part is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly to a counter substrate facing a driving substrate in a liquid crystal display device and a manufacturing method thereof.

  The liquid crystal display device includes a drive substrate and a counter substrate that face each other with a liquid crystal layer interposed therebetween. For example, TFTs (Thin Film Transistor) elements and pixel electrodes are arranged in a matrix corresponding to the pixels in the liquid crystal display device on the driving substrate, and the voltages applied to the pixel electrodes by individually driving the TFT elements are arranged. And thereby controlling the electric field applied to the liquid crystal layer. The image is displayed by controlling the orientation of the liquid crystal by an electric field applied to the liquid crystal layer.

  A spacer having a predetermined height is disposed on the counter substrate, and the distance (cell gap) from the driving substrate is kept constant. By the way, in the manufacturing process of the liquid crystal display device, when the driving substrate and the counter substrate are bonded together, a large pressure is temporarily applied between the substrates, the spacers are irreversibly plastically deformed, and the cell gap becomes non-uniform. There was a problem. If the cell gap is non-uniform, the transmittance of the liquid crystal display device varies and uneven brightness occurs. For this reason, there has been a demand for a method capable of suppressing the plastic deformation of the spacer even when a large pressure is applied between the substrates.

For example, as shown in FIGS. 8A and 8B, Patent Document 1 describes that the spacer formed on the counter substrate 102 is flat with the spacer 131 facing the protruding portion 142 of the drive substrate 101. It is divided into a spacer 132 facing the portion 141. A wiring 112 is formed below the protruding portion 142. One spacer 131 is brought into contact with the protruding portion 142 of the drive substrate 101 to maintain the cell gap, and in this state, a gap 143 is formed between the other spacer 132 and the flat portion 141.
JP 2002-182220 A (FIGS. 6 and 8)

  According to Patent Document 1, when a large pressure is temporarily applied between the substrates, the spacer 132 facing the flat portion 141 of the drive substrate 101 abuts against the flat portion 141 to disperse the pressure. Thus, the spacer 131 for maintaining the cell gap is prevented from being greatly deformed, and plastic deformation is prevented from occurring.

  However, in the liquid crystal display device of the same document, the cell gap is defined by two components, that is, the spacer 131 and the protruding portion 142 of the driving substrate 101, and the height of each of these components varies, so the cell gap tends to vary. There was a problem. Since the variation in the cell gap leads to a decrease in display quality of the liquid crystal display device, a method capable of suppressing the plastic deformation of the spacer 131 while suppressing the variation in the cell gap is desired.

  In view of the above, an object of the present invention is to provide a liquid crystal display device and a method for manufacturing the same that can suppress plastic deformation of a spacer while suppressing variations in cell gaps.

In order to achieve the above object, the liquid crystal display device of the present invention comprises:
In a liquid crystal display device comprising a liquid crystal layer and a first substrate and a second substrate facing each other across a plurality of spacers arranged in the liquid crystal layer,
A film thickness in which at least one of the thin film layers formed on the first substrate has a first part having a predetermined film thickness and a second part having a film thickness smaller than the predetermined film thickness. Formed as a control layer,
The plurality of spacers include a spacer disposed on a surface portion of the first substrate on which the first portion is formed, and a spacer disposed on a surface portion of the first substrate on which the second portion is formed. It is characterized by.

In addition, a method for manufacturing a liquid crystal display device according to the present invention includes:
In a method of manufacturing a liquid crystal display device including a liquid crystal layer and a first substrate and a second substrate facing each other across a plurality of spacers arranged in the liquid crystal layer,
A film thickness including at least one of the thin film layers formed on the first substrate, a first portion having a predetermined film thickness and a second portion having a film thickness smaller than the predetermined film thickness. Patterning as a control layer;
Forming a spacer on each of the surface portion of the first substrate on which the first portion is formed and the surface portion of the first substrate on which the second portion is formed;

  In the liquid crystal display device of the present invention, the spacer disposed in the first portion is brought into contact with the surface of the second substrate to maintain the cell gap, and in this state, the spacer disposed in the second portion and the first A gap is formed between the surfaces of the two substrates. For this reason, when a large pressure is applied between the substrates, the spacer disposed in the second portion contacts the second substrate and disperses the pressure, so that the spacer disposed in the first portion is greatly deformed. Can be suppressed to prevent plastic deformation.

  In the liquid crystal display device of the present invention, since the cell gap can be defined only by the spacer without using the protruding portion on the surface of the driving substrate as in Patent Document 1, the variation in the cell gap is suppressed and the display quality is improved. Reduction can be suppressed.

  In the liquid crystal display device of the present invention, the first substrate may be a color filter substrate, and the film thickness control layer may be a color layer or an overcoat layer covering the color layer. Alternatively, the first substrate may be a monochrome filter substrate, and the film thickness control layer may be an overcoat layer. In the liquid crystal display device of the present invention, the plurality of spacers may have the same height.

In a preferred aspect of the method for producing a liquid crystal display device according to the present invention,
The step of forming the film thickness control layer includes the step of forming a thin film layer having a uniform thickness, and exposing the thin film layer using a photomask having a light transmission part, a light semi-transmission part, and a light shielding part. And developing the thin film layer,
The first part or the second part is formed at a position of the thin film layer corresponding to the light semi-transmissive part.
When patterning as a film thickness control layer by exposing a thin film layer having photosensitivity using a photomask having a light transmission part, a light semi-transmission part, and a light shielding part, the film thicknesses are different from each other. The portion and the second portion can be formed simultaneously. Moreover, the film thickness of the second portion can be easily controlled by adjusting the light transmittance of the light semi-transmissive portion. For the thin film layer, for example, a positive or negative photosensitive resist film can be used.

  In the method for manufacturing a liquid crystal display device according to the present invention, the first substrate may be a color filter substrate, and the film thickness control layer may be a color layer or an overcoat layer covering the color layer. Alternatively, the first substrate may be a monochrome filter substrate, and the film thickness control layer may be an overcoat layer.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Similar to the conventional liquid crystal display device shown in FIG. 8, the liquid crystal display device according to one embodiment of the present invention has a drive substrate and a counter substrate facing each other with a liquid crystal layer interposed therebetween. In the driving substrate, TFT elements and pixel electrodes are arranged in a matrix corresponding to the pixels in the liquid crystal display device, and the TFT elements are individually driven to control the voltage applied to the pixel electrodes. The electric field applied to the liquid crystal layer is controlled. An image can be displayed by controlling the orientation of the liquid crystal by an electric field applied to the liquid crystal layer.

  FIG. 1 is a plan view showing the configuration of the counter substrate in the liquid crystal display device of this embodiment. In this embodiment, the counter substrate 10 is a color filter substrate and includes a transparent glass substrate. On the glass substrate, a black matrix (BM) layer 12 having a light shielding function is formed in a lattice shape along a pixel boundary, thereby constituting a light shielding region 10B. A region surrounded by the light shielding region 10B corresponds to a pixel, and forms a light transmitting region 10A having a light transmitting property.

  Color layers 13 to 15 are formed on the glass substrate so as to cover the black matrix layer 12. The color layers 13 to 15 include color pigments, and selectively transmit, for example, red, green, and blue light, respectively. The color layers 13 to 15 are formed so as to correspond to the respective light transmitting regions 10A, and extend in the column direction of the array of the light transmitting regions 10A, for example. A transparent overcoat layer is formed on the color layers 13 to 15. Columnar spacers 17 and 18 are formed at regular intervals on the overcoat layer. The spacers 17 and 18 are both formed on the BM layer 12.

  2A and 2B are cross-sectional views including spacers 17 and 18 along the lines AA and BB in FIG. 1, respectively. In the vicinity of the spacer 17, as shown in FIG. 2A, the surface of the color layer 13 is flat, and the surface of the overcoat layer 16 on the color layer 13 is also flat. The spacer 17 is formed on the overcoat layer 16 having a flat surface.

  On the other hand, in the vicinity of the spacer 18, as shown in FIG. 2B, a recess 21 is formed in the surface portion of the color layer 14. The overcoat layer 16 is formed along the recess 21 and has a recess 22 reflecting the shape of the recess 21. The spacer 18 is formed inside the recess 22. The recess 22 is formed at a position where the spacer 18 is disposed, for example.

  No spacer is formed on the color layer 15. The thicknesses of the color layers 13 to 15 are equal to each other except the concave portion 21 and are, for example, 0.5 to 3 μm. The thickness of the overcoat layer 16 is preferably such that the level difference due to the BM layer 12 can be eliminated, for example, 0.5 to 3 μm. Moreover, the depth of the recessed part 21 or the recessed part 22 is 0.05-0.3 micrometer, for example.

  Since the spacers 17 and 18 have the same height as each other, the top of the spacer 18 recedes from the top of the spacer 17 by the depth of the recess 22 with reference to the flat portion of the overcoat layer 16. In a state where the counter substrate 10 is bonded to the drive substrate 19, the top portion of the spacer 17 abuts against the drive substrate 19 to maintain a cell gap. In this state, there is a gap between the top portion of the spacer 18 and the drive substrate 19. 20 is formed.

  In the liquid crystal display device of the present embodiment, when a large pressure is applied between the substrates, the spacer 18 abuts against the drive substrate 19 to disperse the pressure. It can be prevented from occurring. Further, since the cell gap can be defined only by the spacers 17 without using the protruding portion on the surface of the drive substrate 19 as in Patent Document 1, it is possible to suppress variations in the cell gap and to suppress deterioration in display quality.

  In the above embodiment, among the color layers 13 and 14 where the spacers 17 and 18 are formed, the surface of the color layer 13 is formed flat, and the concave portion 21 is formed in the color layer 14. Alternatively, each of the color layers 13 and 14 may have a flat portion corresponding to the spacer 17 and a recess 21 corresponding to the spacer 18. Spacers 17 and 18 may also be formed on the color layer 15.

  In manufacturing the counter substrate 10 shown in FIGS. 1 and 2, first, a photoresist film (BM resist film) for the black matrix layer 12 having a light shielding property is applied to the entire surface of the glass substrate 11. Next, the BM resist film is patterned by photolithography to form the black matrix layer 12.

  Subsequently, a photoresist film (color resist film) for the color layer 13 is applied to the entire surface. The color resist film is a negative photosensitive resist in which a pattern is formed by changing to a chemical structure that contains a color pigment and an exposed portion is not dissolved in a developer. Next, exposure using a photomask 30 shown in FIG. FIG. 3A shows a cross section corresponding to FIG.

  The photomask 30 includes a light transmitting portion 31 and a light shielding portion (not shown). The light transmitting portion 31 has a pattern shape corresponding to the color layer 13, and the light shielding portion has a pattern shape corresponding to a region other than the color layer 13. The light transmittance of the light transmitting portion 31 is 100%. Subsequent to exposure using the photomask 30, the substrate is developed using an organic alkaline aqueous solution or the like as a developer. By the development process, the portion of the color resist film 13a corresponding to the light shielding portion is removed, and the pattern of the color layer 13 corresponding to the light transmitting portion 31 is formed.

  Subsequently, a color resist film for the color layer 14 is applied to the entire surface. Similar to the color resist film for the color layer 13, this color resist film is a negative photosensitive resist containing a color pigment. Next, exposure using the halftone mask 32 shown in FIG. FIG. 3B shows a cross section corresponding to FIG. The halftone mask 32 includes a light transmitting part (light transmitting part) 31, a semi-light transmitting part (light semi-transmitting part) 33, and a light shielding part (light shielding part) (not shown). The semi-transparent portion 33 has a pattern shape corresponding to the concave portion 21, and the translucent portion 31 has a pattern shape corresponding to the color layer 14 except for the semi-transparent portion 33. The light shielding portion has a pattern shape corresponding to a region other than the color layer 14. The light transmittance of the light transmitting portion 31 is 100%, and the light transmittance of the semi-light transmitting portion 33 is 50%.

  Subsequent to exposure using the halftone mask 32, the substrate is developed using an organic alkaline aqueous solution or the like as a developer. By the development processing, the portion of the color resist film 14a corresponding to the light shielding portion is removed, and the pattern of the color layer 14 corresponding to the light transmitting portion 31 and the semi-light transmitting portion 33 is formed. Further, the color layer 14 is formed with a thickness corresponding to the intensity of transmitted light, and a portion corresponding to the semi-translucent portion 33 is formed in the recess 21 shown in FIG. The thickness of the color layer 14 can be controlled and the depth of the concave portion 21 can be controlled by adjusting the light transmittance of the semi-translucent portion 33.

  Subsequently, the color layer 15 is formed in the same procedure as the color layer 13. Next, a photoresist (overcoat resist) film for forming the overcoat layer 16 is applied and baked to form the overcoat layer 16. When the overcoat layer 16 is formed, the concave portion 22 is formed reflecting the shape of the concave portion 21 of the color layer 14.

  Subsequently, a photoresist film (PS resist film) for the spacers 17 and 18 is applied on the overcoat layer 16. Next, the PS resist film is patterned by photolithography to form spacers 17 and 18 having the same height. The spacer 17 is formed in the flat portion of the overcoat layer 16, and the spacer 18 is formed in the recess 22 of the overcoat layer 16. Furthermore, it is heated and fired at a temperature of about 230 ° C. in an oven.

  According to the manufacturing method described above, by performing exposure using the halftone mask 32, the color layer 14 having the recesses 21 can be formed by only one exposure process. Further, the depth of the recess 21 can be easily controlled by adjusting the transmittance of the semi-translucent portion 33. By adjusting the depth of the recess 21 to an optimal value, plastic deformation of the spacer 17 can be effectively suppressed.

  The recess 21 may be a complete notch. In this case, a photomask having a light shielding portion corresponding to the recess 21 is used. In forming the color layer 14 using the halftone mask 32, a positive photosensitive resist may be used instead of the negative photosensitive resist.

  FIG. 4 is a cross-sectional view of the counter substrate in the liquid crystal display device according to the first modification of the embodiment. This figure shows a cross section corresponding to FIG. The counter substrate 40 has the same configuration as the counter substrate 10 of the embodiment shown in FIGS. 1 and 2 except that a concave portion 41 is formed in the surface portion of the overcoat layer 16 instead of the color layer 14. have.

  In manufacturing the counter substrate 40 of FIG. 4, a photomask having a light transmitting portion and a light shielding portion is used instead of the halftone mask 32 when the color layer 14 is exposed. A negative photosensitive resist is applied as the overcoat resist film, and the overcoat resist film 16a is exposed using the halftone mask 42 shown in FIG.

  The halftone mask 42 includes a translucent portion 31 and a semi-transparent portion 33, and the semi-transparent portion 33 has a pattern shape corresponding to the concave portion 41. The light transmittance of the light transmitting portion 31 is 100%, and the light transmittance of the semi-light transmitting portion 33 is 50%.

  In developing the overcoat resist film 16a after exposure, a developer such as an organic alkaline aqueous solution is used. By the development process, the overcoat layer 16 is formed to a thickness corresponding to the intensity of transmitted light, and a portion corresponding to the semi-translucent portion 33 is formed in the concave portion 41 shown in FIG. In addition, by adjusting the light transmittance of the semi-translucent portion 33, the thickness of the overcoat layer 16 can be controlled, and the depth of the concave portion 41 can be controlled. When forming the spacers 17 and 18, the spacer 18 is formed inside the recess 41 of the overcoat layer 16.

  6A and 6B are cross-sectional views corresponding to FIGS. 2A and 2B, respectively, of the counter substrate in the liquid crystal display device according to the second modification of the embodiment. The counter substrate 50 is a monochrome filter substrate, does not have the color layers 13 to 15, and the overcoat layer 16 is directly formed on the glass substrate 11 so as to cover the BM layer 12. Except for the above, the counter substrate 50 has the same configuration as the counter substrate 40 shown in FIG. 4, and a recess 51 is formed in the surface portion of the overcoat layer 16 on which the spacer 18 is disposed. .

  In manufacturing the counter substrate 50 of FIG. 6, the color layers 13 to 15 are not formed. Further, when the overcoat layer 16 is exposed, as shown in FIG. 7, the overcoat layer 16 is exposed using a halftone mask 52 having the same configuration as the halftone mask 42 of FIG.

  Although the present invention has been described based on the preferred embodiment, the liquid crystal display device and the manufacturing method thereof according to the present invention are not limited to the configuration of the above embodiment, and the configuration of the above embodiment. Various modifications and changes are also included in the scope of the present invention.

  For example, in the embodiment and the first and second modified examples, the concave portion is formed in the color layer or the overcoat layer formed on the counter substrate, but the concave portion is formed in the layer formed on the driving substrate. May be. In the embodiment and the first and second modified examples, the recess is formed at a position where the spacer is disposed. However, there is no limitation on the size of the region where the recess is formed.

It is a top view of the opposing board | substrate in the liquid crystal display device which concerns on one Example of this invention. 2A and 2B are sectional views taken along lines AA and BB in FIG. 1, respectively. FIGS. 3A and 3B are cross-sectional views showing one manufacturing stage for manufacturing the counter substrate of FIG. It is sectional drawing corresponding to FIG.2 (b) about the opposing board | substrate in the liquid crystal display device which concerns on the 1st modification of an Example. FIG. 5 is a cross-sectional view showing a manufacturing stage for manufacturing the counter substrate of FIG. 4. 6A and 6B are cross-sectional views corresponding to FIGS. 2A and 2B, respectively, of the counter substrate in the liquid crystal display device according to the second modification of the embodiment. FIG. 7 is a cross-sectional view showing a manufacturing stage for manufacturing the counter substrate of FIG. 6. 8A and 8B are cross-sectional views of the liquid crystal display device of Patent Document 1. FIG.

Explanation of symbols

10: Counter substrate 10A: Translucent area 10B: Light shielding area 11: Glass substrate 12: Black matrix (BM) layer 13: Color layer 13a: Color resist film 14: Color layer 15: Color layer 16: Overcoat layer 16a: Over Coat resist film 17: Spacer 18: Spacer 19: Driving substrate 20: Gap 21: Concave 22: Concave 30: Photomask 31: Translucent part 32: Halftone mask 33: Semitransparent part 40: Counter substrate 41: Concave 42 : Halftone mask 50: counter substrate 51: recess 52: halftone mask 101: driving substrate 102: counter substrate 103: liquid crystal layer 111: transparent substrate 112: wiring 113: insulating layer 114: wiring 115: overcoat layer 116: orientation Layer 121: Transparent substrate 122: Black matrix layer 123: Overcoat layer 124: Orientation layer 131: S P o 132: spacer 141: flat portion 142: protrusion 143: gap

Claims (6)

In a liquid crystal display device comprising a liquid crystal layer and a first substrate and a second substrate facing each other across a plurality of spacers arranged in the liquid crystal layer,
A film thickness in which at least one of the thin film layers formed on the first substrate has a first part having a predetermined film thickness and a second part having a film thickness smaller than the predetermined film thickness. Formed as a control layer,
The plurality of spacers include a spacer disposed on a surface portion of the first substrate on which the first portion is formed, and a spacer disposed on a surface portion of the first substrate on which the second portion is formed. A liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the first substrate is a color filter substrate, and the film thickness control layer is a color layer or an overcoat layer covering the color layer.   The liquid crystal display device according to claim 1, wherein the plurality of spacers have the same height. In a method of manufacturing a liquid crystal display device including a liquid crystal layer and a first substrate and a second substrate facing each other across a plurality of spacers arranged in the liquid crystal layer,
A film thickness including at least one of the thin film layers formed on the first substrate, a first portion having a predetermined film thickness and a second portion having a film thickness smaller than the predetermined film thickness. Patterning as a control layer;
Forming a spacer on the surface portion of the first substrate on which the first portion is formed and on the surface portion of the first substrate on which the second portion is formed. Production method. The step of forming the film thickness control layer includes the step of forming a thin film layer having a uniform thickness, and exposing the thin film layer using a photomask having a light transmission part, a light semi-transmission part, and a light shielding part. And developing the thin film layer,
The method for manufacturing a liquid crystal display device according to claim 4, wherein the first portion or the second portion is formed at a position of the thin film layer corresponding to the light semi-transmissive portion.   The method for manufacturing a liquid crystal display device according to claim 4, wherein the first substrate is a color filter substrate, and the film thickness control layer is a color layer or an overcoat layer covering the color layer.

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