JPH1068956A - Liquid crystal display element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display element which is enhanced in yield and has good display characteristics by consisting of the element of pixel electrodes and a liquid crystal layer arranged in the spacing between an array substrate having columnar projections and a counter substrate and forming the layers consisting of the same material as the material of the pixel electrodes material in a part on the counter substrate side of these columnar projections. SOLUTION: The pixel electrodes 10 are connected to TFT drain electrodes via through-holes formed in colored layer parts. An oriented film 12 is formed over the entire surface including the columnar projections 9. Light shielding layers 7 are formed in order to prevent the incidence of light to the TFT parts in the positions corresponding to the TFTs. The layers 11 consisting of the same material as the pixel electrode material are formed over the entire surface on the counter substrate side of the columnar projections 9. These layers 11 are arranged spatially from the pixel electrodes 10, i.e., are patterned in a non-connected state. As a result, the damage at the apexes of the columnar projections 9 by etching is prevented and the columnar projections having always the specified height are obtd. The yield is N thus enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly to a columnar spacer for maintaining a distance between two substrates.

[0002]

2. Description of the Related Art A liquid crystal display device is disclosed in JP-A-7-84267.
As shown in FIG. 1, it has been considered to use a columnar projection made of an organic resin or the like as a spacer for keeping the distance between two substrates constant.

[0003]

However, in the case of forming columnar projections on the array substrate side, if the columnar projections are formed before forming the pixel electrodes, the columnar projections can be formed with an etching solution for patterning and forming the pixel electrodes. It is difficult to always obtain a liquid crystal display element having columnar projections having a predetermined height, which is likely to be damaged, and the possibility of deteriorating display performance increases. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a liquid crystal display element having a high yield and good display characteristics, and a method for manufacturing the same.

[0004]

According to the liquid crystal display device and the method of manufacturing the same of the present invention, a layer of the same material as the pixel electrode material is formed also on the opposing substrate side of the columnar projection. The thickness of the layer portion of the material also functions as a spacer for maintaining the distance between the two substrates, and the columnar protrusion formed on the array substrate side is made to have a thickness equal to the thickness of the layer of the same material as the pixel electrode material than the desired spacer height. Can be lowered. This is particularly effective when a spacer layer is formed in the same step as the coloring layer, and this spacer layer is laminated to form columnar projections. This is because the degree of freedom in designing the thickness of the colored layer is small due to the desired color and the light transmittance and spectral characteristics of the colored layer itself. In order to obtain a desired color and transmittance, a colored layer having a thickness of 1 to 2 μm is generally required. If the thickness is too large, disadvantages such as a decrease in transmittance occur. For example, in the case of forming colored layers of three colors, a spacer layer of three colors is formed in each colored layer forming step, and these are laminated to form columnar projections. Will depend on In this case, even if the columnar projections are formed by laminating three layers, the first layer is substantially a colored layer portion, so that the spacer layer that defines the thickness of the liquid crystal layer is two, and the thickness of the liquid crystal layer is two. ４4 μm. Generally, the thickness of the liquid crystal layer is designed to be about 4 to 5 μm. In consideration of the transmittance of the colored layer, the height of the columnar projections tends to be smaller than the desired thickness of the liquid crystal layer. Can be supplemented by a layer of the same material as the pixel electrode material.

In the case where columnar projections are formed on the array substrate side, the columnar projections are formed before forming the pixel electrodes, and when the pixel electrodes are patterned, the same material as the pixel electrode material is formed on the tops of the columnar projections. By patterning so that the layer remains, the columnar projection is not damaged by the etching solution. The same effect can be obtained by patterning the transparent electrode by dry etching instead of wet etching using an etching solution.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a sectional view of a liquid crystal display device. As shown in FIG. 1, the liquid crystal display element 30 of the present embodiment has a liquid crystal layer 24 interposed between an array substrate 31 and a counter substrate 32, and is formed on the outer periphery of the array substrate 30 and the counter substrate 31. The two substrates are adhered to each other by a sealing material (not shown).
The distance between the substrate 1 and the substrate 1 is held by the columnar projection 9.

In the array substrate 31, a plurality of signal lines (not shown) and a plurality of gate lines 2 are formed on one main surface of the substrate 1 so as to intersect with each other. Each time, a TFT (thin film transistor) as a switching element 22 and a pixel electrode 10 electrically connected thereto are formed. The switching element 22 includes a source electrode 5 formed to be connected to a signal line, and a drain electrode 6 formed in the same layer as the signal line, via the semiconductor layer 4. On the entire surface of the substrate including the gate lines, the signal lines, and the switching elements, a colored layer composed of organic resin films of three colors of R (red), G (green), and B (blue) is formed. Columnar projections are formed, and the columnar projections are formed by laminating a spacer layer formed in the same step as the coloring layer. The adjacent colored layers of different colors are formed so as to overlap each other, and the overlapped colored layer portions correspond to the spacer layers of the respective colored layers, and the spacer layers formed in the same process as the colored layers of other colors are Columnar projections are formed in these overlapping regions, and the three spacer layers form columnar projections. The pixel electrode 10 is connected to the drain electrode of the TFT via a through hole formed in the colored layer portion. Then, an alignment film 12 is formed on the entire surface of the substrate including the columnar protrusions. A light shielding layer 7 is formed at a position corresponding to the TFT in order to prevent light from entering the TFT portion. A layer 11 of the same material as the pixel electrode material is formed on the entire surface of the columnar projection 9 on the counter substrate side. The layer of the same material as the pixel electrode material is disposed separately from the pixel electrode 10, that is, in a non-connected state. Is patterned.

On the other hand, the counter substrate 32 is formed by sequentially forming the counter electrode 25 and the alignment film 12 on the entire surface of the substrate 21. Next, the manufacturing process of this embodiment will be described.

First, the manufacturing process of the counter substrate 32 will be described. A counter electrode 25 was formed on the substrate 21 by sputtering an ITO film to a thickness of 1500 °. Next, polyimide (trade name A manufactured by Nippon Synthetic Rubber Co., Ltd.) was used as an alignment film material.
L-1051) was applied to the entire surface by 500 angstroms, and rubbing treatment was performed to form an alignment film 12 to form a counter substrate 32.

Next, a manufacturing process of the array substrate 31 will be described. MoTa (molybdenum / tungsten) on the substrate 1
Alternatively, a film of MoTa (molybdenum / tantalum) or the like was formed by sputtering, and this was patterned by a photolithography method to form a gate electrode and a gate line 2, and an auxiliary capacitance line (not shown). Next, silicon oxide or silicon nitride was deposited to a thickness of 4000 angstroms on the entire surface of the substrate including these gate lines, gate electrodes, and auxiliary capacitance lines by a plasma CVD method to form a gate insulating film 3.

A semiconductor layer 4 made of a-Si (amorphous silicon) was formed thereon by a plasma CVD method and patterned into a predetermined shape. Further, an electrode made of Mo / Al / Mo was formed via an ohmic contact layer, and was patterned into a predetermined shape to form a source electrode 5, a drain electrode 6, and a signal line. Further, a black resin film 7 was coated on the TFT in order to prevent the TFT from malfunctioning due to external light.

Next, a UV-curable acrylic resin resist CR-2000 (manufactured by Fuji Hunt Technology Co., Ltd.) in which a red pigment is dispersed is applied over the entire surface by a spinner, and red is colored including a portion where spacer formation is desired. 365 nm through a photomask that irradiates the desired part with light
At a wavelength of 100 mJ / cm 2 and developed with a 1% aqueous solution of KOH for 10 seconds to form a red colored layer 8R and a red spacer layer 9R constituting columnar projections. Similarly, green and blue colored layers 8G and 8B and green and blue spacer layers 9G and 9B were formed. Here, the green coloring material is CG-2000 (manufactured by Fuji Hunt Technology Co., Ltd.), and the blue coloring layer is CB-2000.
2000 (manufactured by Fuji Hunt Technology Co., Ltd.).
The columnar protrusions were formed by laminating spacer layers of three colors, and were arranged at positions corresponding to the TFTs via the black resin film 7.

Next, a through hole 9 was formed in the colored layer 8, and a transparent electrode made of ITO was formed on the entire surface of the substrate having columnar projections. A resist is applied to the entire surface of the transparent electrode, and the resist is removed from portions other than the positions corresponding to the layer portions of the same material as the pixel electrode material and the pixel electrode material formed on the counter substrate side of the columnar protrusions. Was removed by dry etching, and after the electrode patterning, all the resist was removed to obtain a layer of the same material as the pixel electrode and the pixel electrode material. At this time, the transparent electrode was patterned so as to be in contact with the drain electrode 6 to form the pixel electrode 10.

Finally, polyimide (trade name: AL-1051, manufactured by Nippon Synthetic Rubber Co., Ltd.) is used as an alignment film material on the entire surface.
The alignment substrate 12 was formed by applying 00 angstrom and performing a rubbing treatment to form an array substrate 31.

Thereafter, a sealant for bonding the two substrates is printed on the outer peripheral portion of the opposing substrate 32 except for an injection port (not shown), and a voltage is applied from the array substrate 31 to the opposing electrode 25. Transfer material was formed on the electrode transfer electrode around the sealing material application region. Next, the two substrates are aligned with the alignment film 1.
The substrates 31 and 32 were arranged such that the rubbing direction of each alignment film was 90 degrees, and the two substrates were bonded by heating to cure the sealant.

Next, as a liquid crystal composition 20, a material obtained by adding 0.1 wt% of S811 to ZLI-1565 (manufactured by E. Merck) is injected from the injection port by an ordinary method. Then, the liquid crystal display element 30 was formed.

As described above, when the pixel electrode is formed, it is designed so that the layer of the same material as the pixel electrode material is also left on the opposing substrate side of the columnar projection, so that the resist formed on the opposing substrate side of the columnar projection is formed. The influence of the dry etching is cut off, and there is no damage such as the opposing substrate side of the columnar projection being scraped off by etching. Therefore, since it is not necessary to consider a change in height due to damage to the columnar projection due to the etching process when forming the pixel electrode pattern, the columnar projection that maintains the distance between the substrates can always be formed at a constant height. It will be easier.

Next, a second embodiment will be described with reference to FIG. This embodiment exemplifies a liquid crystal display element using p-Si while the semiconductor layer of the above embodiment is a-Si.

FIG. 2 is a sectional view of a liquid crystal display device. FIG.
As shown in FIG. 5, the liquid crystal display element 30 of the present embodiment has a liquid crystal layer 24 interposed between the array substrate 31 and the opposing substrate 32, and a seal formed on the outer peripheral portions of the array substrate 30 and the opposing substrate 31. Both substrates are bonded together by a material (not shown), and the distance between the array substrate 30 and the opposing substrate 31 is held by the columnar projections 9.

On an array substrate 31, a plurality of signal lines (not shown) and a plurality of gate lines 2 are formed on one main surface of the substrate 1 so as to intersect with each other. A TFT (thin film transistor) as a switching element 22 and a pixel electrode 10 electrically connected thereto are formed. Specifically, a semiconductor layer 4 made of p-Si is formed on the substrate 1, and a gate insulating film 23 is formed so as to cover the semiconductor layer 4. The gate 2 is formed at a position corresponding to the semiconductor layer 52 on the gate insulating film 23, and a silicon oxide film 29 and a silicon nitride film 26 are formed to cover the gate insulating film 23 and the gate 2. Silicon nitride film 26, silicon oxide film 29, gate insulating film 2
3, a through hole is formed, and a drain electrode 6 is formed.
And a source 5 electrode is electrically connected to the semiconductor layer 4. An organic insulating film 27 made of acrylic resin or the like is formed so as to cover these structures. A through hole 28 is formed on the drain 6 of the insulating film 27, and the drain 6 is formed through the through hole 28. And the pixel electrode 10 are connected. An alignment film 12 is formed on the entire surface.

On the other hand, the counter substrate 32 is formed by sequentially forming the counter electrode 25 and the alignment film 12 on the entire surface of the substrate 21. In this embodiment, the organic insulating film 27 and the columnar protrusion 9 are formed in different steps. In the patterning of the pixel electrode, wet etching is used. Hereinafter, only the details of the patterning step will be described. After the organic insulating film 27 was formed on the entire surface of the substrate, columnar projections were formed at positions corresponding to the TFTs using the same material as the organic insulating film 27 by photolithography. Through hole 28 in organic insulating film 27
Was formed, a transparent electrode made of ITO was formed on the entire surface of the substrate having the columnar protrusions.

A resist is applied to the entire surface of the transparent electrode, and a portion corresponding to the pixel electrode portion and a portion of the columnar projection farthest from the array substrate, that is, a pixel electrode material formed on the counter substrate side when a liquid crystal display element is formed. The resist other than the position corresponding to the layer of the same material as the above is removed, the transparent electrode in the portion where the resist is removed is removed by etching with aqua regia, and after the electrode patterning, all the resist is removed, and the pixel electrode 10 and the pixel electrode material are removed. A layer 11 of the same material was obtained. At this time, the pixel electrode 10 and the drain electrode 6 were formed so as to be electrically connected through the through hole 28.

As described above, when a layer of the same material as the pixel electrode material is formed, it is designed so that the layer of the same material as the pixel electrode material is also left on the opposing substrate side of the columnar protrusion. The formed resist blocks the influence of the wet etching, so that there is no damage such as the top of the columnar projection being etched away. Therefore, since it is not necessary to consider a change in height due to damage to the columnar projection due to the etching process at the time of forming the pixel electrode, it is easy to always form the columnar projection that maintains the distance between the substrates at a constant height. Becomes

In the first embodiment, dry etching is used when forming a pixel electrode and a layer made of the same material as the pixel electrode material. In the second embodiment, wet etching in which aqua regia is used is used. In either case, the same effect can be obtained. That is, the resist formed on the opposing substrate side of the columnar projections at the time of the electrode pattern blocks the influence of the etching, and there is no damage such as the opposing substrate side of the columnar projections being etched away.

In the first embodiment, a layer made of the same material as the pixel electrode material is formed on the entire surface of the columnar protrusion on the side of the opposing substrate. In the second embodiment, a part of the columnar protrusion is formed on the side of the opposing substrate. Although a layer made of the same material as the pixel electrode material is formed, the same effect can be obtained in either case, and a columnar projection having a constant height can always be obtained. However, in order to always obtain a columnar protrusion having a constant thickness in addition to the height, it is preferable to form a layer of the same material as the pixel electrode material on the entire surface of the columnar protrusion on the counter substrate side. Columnar projections having a constant thickness can be obtained.

In the first embodiment, the layer of the same material as the pixel electrode material and the pixel electrode are not connected. In the second embodiment, the pixel electrode and the layer of the same material as the pixel electrode material are separated. Although the connection state is established, a similar effect can be obtained in either case, and a columnar projection having a constant thickness can be always obtained. However, when the pixel electrode and a layer of the same material as the pixel electrode material are connected, a short circuit occurs between the pixel electrode and the counter electrode on the counter substrate, and the possibility of display failure is high. It is preferable that the layer of the same material as described above and the pixel electrode are in a non-connected state. In the case where the layer of the same material as the pixel electrode material and the pixel electrode are not connected in this manner, the cross-sectional area of the columnar protrusion substantially parallel to the array substrate is partially increased from the array substrate side to the counter substrate side. By forming the columnar projections in such a manner, when forming a transparent electrode on the entire surface of the substrate including the columnar projections, it is difficult to form the transparent electrode on the side surfaces of the columnar projections, and it is possible to further prevent a short circuit.

In the above two embodiments, a colored layer or an organic insulating film is formed on the entire surface of the substrate including the gate lines, signal lines, and switching elements, and columnar projections are formed via these colored layers or the organic insulating film. However, similar effects can be obtained even if these colored layers or organic insulating films are not formed. When a colored layer or an organic insulating film is formed as in the above embodiment, the pixel electrode is
Since the gate electrode can be formed so as to overlap with a signal line or a gate line with an insulating film interposed therebetween, an aperture ratio can be increased. In addition, when the colored layer is formed on the array substrate side, compared with the case where the colored layer is formed on the counter substrate side, it is not necessary to consider a misalignment between the pixel electrode and the colored layer. It is possible to give. Also,
In the first embodiment, since the columnar projections can be formed in the same step as the colored layer forming step, the number of steps can be reduced as compared with the case where the columnar projections are formed separately from the colored layer forming step.

Further, in the above two embodiments, the columnar protrusions are formed on the TFT, but may be formed in a non-pixel region such as a signal line or a gate line. Further, in the first embodiment, since the adjacent colored layers overlap, the light transmittance of the overlapping portion is low. Therefore, when the overlapping region of the colored layers is arranged on the wiring layer, Light leakage of the wiring layer portion can be prevented as compared with the case where they do not overlap.

The present invention is not limited to the above embodiment. As described above, in the present invention, since a layer made of the same material as the pixel electrode material is also formed on the opposite substrate side of the columnar protrusion, the distance between the two substrates is maintained by the thickness of the layer portion made of the same material as the pixel electrode material. The columnar projections that function as spacers and are formed on the array substrate side can be made lower than the desired spacer height by the thickness of the layer of the same material as the pixel electrode material. Further, in the present invention, when forming a plurality of pixel electrodes on a substrate having columnar projections, by manufacturing such that a layer of the same material as the pixel electrode material is formed on a part of the columnar projections on the side of the opposing substrate. In addition, it is possible to prevent damage to the tops of the columnar projections due to etching during the formation of the pixel electrodes, and to obtain columnar projections having a constant height.

[0030]

According to the present invention, when a plurality of pixel electrodes are formed on an array substrate having columnar projections, part of the columnar projections on the counter substrate facing the array substrate is made of the same material as the pixel electrode material. By patterning the electrodes so that a layer is formed, damage to the tops of the columnar projections due to etching at the time of forming the pixel electrode can be prevented, and columnar projections having a constant height can always be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a sectional view of a liquid crystal display device showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Gate line 8 ... Coloring layer 9 ... Columnar protrusion 10 ... Pixel electrode 11 ... Layer of the same material as pixel electrode material 21 ... Substrate 22 ... Switching element 24 ... Liquid crystal layer 25 ... Counter electrode 30 ... Liquid crystal display element 31 … Array substrate 32… counter substrate

Claims (14)

[Claims] A counter substrate having a counter electrode; a plurality of gate lines; a plurality of signal lines intersecting with the gate lines; a switching element near an intersection of the gate lines and the signal lines; An array substrate having a pixel electrode connected to the switching element, and a columnar protrusion disposed at a position corresponding to any one of the gate line, the signal line, and the switching element, the counter substrate, and the array substrate; A liquid crystal display element comprising a liquid crystal layer disposed in a gap between the columnar projections, wherein the columnar projections are formed on a part of the counter substrate side with a layer made of the same material as the pixel electrode material. . 2. A counter substrate having a counter electrode, a plurality of gate lines, a plurality of signal lines intersecting with the gate lines, and a switching element near an intersection between the gate lines and the signal lines. An organic insulating film formed on the entire surface of the substrate including the gate line, the signal line, and the switching element; and the organic insulating film at a position corresponding to any one of the gate line, the signal line, and the switching element. An array substrate having columnar projections disposed on a film, and a transparent electrode formed on the organic insulating film including the columnar projections; and a liquid crystal layer formed in a gap between the counter substrate and the array substrate. In the liquid crystal display device, the column-shaped projection is formed on a part of the opposing substrate side with a layer made of the same material as the pixel electrode material. 3. The organic insulating film comprises a plurality of colored layers, and the columnar protrusions are formed by laminating a plurality of spacer layers formed in the same step as the colored layer. 2. The liquid crystal display device according to 2. 4. The liquid crystal display device according to claim 3, wherein the adjacent colored layers overlap each other, and the overlapped portion forms a part of the columnar projection. 5. The liquid crystal display device according to claim 1, wherein the layer of the same material as the pixel electrode material and the pixel electrode are formed in the same step. 6. The liquid crystal display device according to claim 1, wherein a layer made of the same material as the pixel electrode material is formed on the entire surface of the columnar protrusion on the side of the counter substrate. 7. The liquid crystal display device according to claim 1, wherein the pixel electrode and a layer made of the same material as the material of the pixel electrode are separated from each other. 8. The cross-sectional area of the columnar projection substantially parallel to the array substrate is partially increased from the array substrate side to the counter substrate side. A liquid crystal display device according to any one of the above. 9. A step of forming a counter electrode by forming a counter electrode; forming a plurality of gate lines on the substrate; a plurality of signal lines intersecting the gate lines; Forming a switching element in the vicinity of the intersection with the above, forming a columnar projection at a position corresponding to at least one of the gate line, the signal line, and the switching element; and the columnar projection. Forming a transparent electrode on the entire surface of the substrate; patterning the transparent electrode to form a pixel electrode connected to the switching element; and forming a portion of the columnar projection farthest from the array substrate with the same material as the pixel electrode material. Forming a layer of material to form an array substrate, and disposing the counter substrate and the array substrate to face each other, and maintaining the distance between the substrates by the columnar protrusions, A step of disposing a sealant on the outer periphery of the counter substrate and the array substrate to bond the counter substrate and the array substrate, and a step of forming a liquid crystal layer in a substrate gap between the counter substrate and the array substrate And a method for manufacturing a liquid crystal display element having the following. 10. A step of forming a counter electrode by forming a counter electrode, forming a plurality of gate lines on the substrate, a plurality of signal lines intersecting the gate lines, and the gate lines and the signal lines. Forming a switching element in the vicinity of the intersection with the substrate, forming an organic insulating film on the entire surface of the substrate including the gate line, the signal line, and the switching element; and forming the organic insulating film on the gate line, the signal line, and the switching element. Forming a columnar protrusion on the organic insulating film at a position corresponding to at least one of the above, forming a transparent electrode on the organic insulating film including the columnar protrusion, and patterning the transparent electrode. Forming a layer of the same material as the pixel electrode material on a portion of the pixel electrode connected to the switching element and a part of the columnar protrusion farthest from the array substrate; And forming the counter substrate and the array substrate to face each other, and maintaining a distance between the substrates by the columnar projections, disposing a sealing material on the outer peripheral portions of the substrate of the counter substrate and the array substrate. A method of manufacturing a liquid crystal display element, comprising: a step of bonding the opposite substrate and the array substrate; and a step of forming a liquid crystal layer in a substrate gap between the opposite substrate and the array substrate. 11. The organic insulating film comprises a plurality of colored layers, and the columnar protrusions are formed by laminating a plurality of spacer layers formed in the same step as the colored layer. 10. The method for manufacturing a liquid crystal display element according to item 9. 12. The liquid crystal display element according to claim 8, wherein a layer made of the same material as the pixel electrode material is formed on the entire surface of the columnar protrusion on the side of the counter substrate. Method. 13. The method according to claim 8, wherein the pixel electrode and a layer made of the same material as the pixel electrode material are separated and patterned. 14. The cross-sectional area of the columnar projection substantially parallel to the array substrate is partially increased from the array substrate side to the counter substrate side. A method for manufacturing a liquid crystal display device according to any one of the above.