JPH11326949A - Active matrix type liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a dot detect due to a defect in the conduction of a liquid crystal display element by securely forming a through hole for electrically connecting a pixel electrode, a source electrode, and a pixel electrode, and an auxiliary capacity electrode arranged across colored insulating films without any decrease in manufacture yield, and to obtain excellent display quality by preventing the aperture rate of the liquid crystal display element form decreasing owing to the through hole to improve the lightness and contrast. SOLUTION: A single through hole 47 which penetrates an organic resin insulating film 43 and a transparent protection insulating film 42 to reach the source electrode 37 and auxiliary capacity electrode 38 is formed above a gate line 33, and the pixel electrode 44a and a source electrode 37 of a precedent stage and the pixel electrode 44b and auxiliary capacity electrode 38 of te following stage are electrically connected to reduce the number of processes of the through hole 47 of the colored insulating layer 43 which is a thick film and hard to process to a half and also the light shield area in the pixel electrode 44 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display in which pixel electrodes are driven by switching elements arranged in a matrix in a liquid crystal display having a liquid crystal composition held between electrode substrates. .

[0002]

2. Description of the Related Art In recent years, a liquid crystal display device which is thin, lightweight, high-density and large-capacity, yet has high performance and high definition has been developed. In order to increase the aperture ratio, a transparent pixel electrode is required.
Attention has been paid to a liquid crystal display element having a pixel-mounted structure, which is arranged so as to cover a switching element such as a thin film transistor (hereinafter referred to as a TFT) or a metal / insulating film / metal (MIM) element. Further, since it is not necessary to consider a deviation from a color filter and an improvement in manufacturing yield can be obtained, an active matrix type liquid crystal display using an array substrate of a color filter integrated type in which an organic resin insulating film is formed under a pixel electrode. A device was being developed.

An active matrix type liquid crystal display device using such an array substrate integrated with a color filter has conventionally been formed as shown in FIGS. That is, the array substrate 2 of the liquid crystal display element 1 is formed integrally with the organic resin insulating film 11 which is a color filter, and the switching of the pixel electrode 6 is provided at the intersection of the signal line 3 and the gate line 4 on the array substrate 2. A TFT 7 as an element is formed. The source electrode 8 of the TFT 7 and the previous pixel electrode 6a
Are electrically connected through a first through hole 12 penetrating the transparent insulating film 10 and the organic resin insulating film 11 to form an auxiliary capacitance electrode 13 forming an auxiliary capacitance with the gate line 4 and a next-stage pixel electrode 6b Are the transparent insulating film 10 and the organic resin insulating film 1
1 are electrically connected via a second through hole 14 penetrating through the first through hole 1.

Generally, in order to obtain a color filter having sufficient color purity for obtaining a color display, it is necessary to increase the thickness of an organic resin insulating film constituting the color filter to about 3 μm.

[0005]

In a conventional color filter-integrated array substrate on which a pixel electrode is placed, a preceding pixel electrode and a source electrode are provided through two through holes penetrating an organic resin insulating film. Alternatively, the pixel electrode and the auxiliary capacitance electrode at the next stage are electrically connected to each other. On the other hand, the thickness of the organic resin insulating film constituting the color filter needs to be as thick as about 3 μm in order to obtain a color filter having sufficient color purity for performing good color display.

For this reason, the through-hole formed through the thick organic resin insulating film is difficult to process, and the through-hole cannot be completely formed, resulting in defective formation and display defects such as point defects. This has caused a problem that the display quality of the liquid crystal display element is easily deteriorated. Moreover, since two through-holes per pixel electrode are required in a thick organic resin insulating film, which is difficult to process with the conventional array substrate, the yield of the array substrate due to defective formation of through-holes is further reduced. I was

Further, since the organic resin insulating film is a thick film, the minimum processing size of the through hole diameter is as large as 10 μm or more.
The liquid crystal display device using such an array substrate has a problem that the aperture ratio is reduced and the display quality is significantly reduced due to the reduction in brightness and contrast.

Therefore, the present invention solves the above-mentioned problems, and electrically connects a previous pixel electrode and a source electrode or a next pixel electrode and an auxiliary capacitor electrode through a through hole penetrating an organic resin insulating film. When connecting, prevent poor formation of through holes, prevent display quality degradation due to display defects such as point defects, and prevent through holes from lowering the aperture ratio of the liquid crystal display area. It is an object of the present invention to provide an active matrix liquid crystal display device capable of improving image brightness and contrast and performing high-quality display.

[0009]

In order to solve the above-mentioned problems, the present invention provides a gate line on an insulating substrate, a signal line wired so as to intersect the gate line, and an intersection of the gate line and the signal line. A semiconductor layer having at least a source region and a drain region sandwiching a channel region, a gate electrode integral with the gate line, a source electrode connected to the source region, and a drain electrode connected to the drain region An element, an auxiliary capacitance electrode forming an auxiliary capacitance with the gate line, an organic resin insulating film covering the switching element and the auxiliary capacitance electrode, and being surrounded by the gate line and the signal line on the organic resin insulating film. Are arranged in a matrix in a region to be connected and connected to the source electrode via through holes formed in the organic resin insulating film. A liquid crystal display device comprising: an array substrate having pixel electrodes; a counter substrate disposed to face the array substrate with a gap therebetween; and a liquid crystal composition sealed between the array substrate and the counter substrate. An auxiliary capacitance electrode is exposed from the organic resin insulating film through a common through hole with the source electrode, and the pixel electrode connected to the source electrode and another pixel electrode adjacent to the pixel electrode with the gate line interposed therebetween. They are connected via through holes.

According to the present invention, according to the present invention, a single through-hole extending from a source electrode to an auxiliary capacitance electrode is formed through an organic resin insulating film, and a pixel electrode of a preceding stage is connected to a source through the single through-hole. The electrode or the next stage pixel electrode is electrically connected to the auxiliary capacitance electrode, the number of through holes per pixel electrode formed in the thick organic resin insulating film is reduced to one, and the number of processing is reduced. Moreover, by improving the workability by enlarging the processing size of a single through hole,
An object of the present invention is to improve the production yield, prevent point defects due to defective through-hole formation, and improve the display quality of a liquid crystal display device. Further, by arranging the through-holes on the gate lines, the aperture ratio of the liquid crystal display element is enlarged, and the brightness and contrast of the displayed image are improved to improve the display quality.

[0011]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS. Reference numeral 17 denotes an active matrix type liquid crystal display element, and an array substrate 20 using the pixel TFT 18 as a switching element of the pixel electrode 44.
And a counter substrate 21, a nematic liquid crystal 24 as a liquid crystal composition is sealed through alignment films 22 and 23. Reference numerals 26 and 27 denote polarizing plates that are attached to the outside of the array substrate 20 and the opposing substrate 21, respectively.

The array substrate 20 has a semiconductor layer 30 having a channel region 30a made of polycrystalline silicon and a source region 30b and a drain region 30c made of polycrystalline silicon with low resistance on a transparent insulating substrate 28 made of transparent glass or the like. Is formed thereon, and a 400 nm-thick tantalum (Ta), chromium (C) film is formed thereon via a gate insulating film 31 made of silicon oxide (SiOx) having a thickness of 100 nm.
r), a metal such as aluminum (Al), molybdenum (Mo), tungsten (W), copper (Cu), or a simple substance of these metals, a laminated film or an alloy film thereof, and the gate electrode 32 is integrally formed. A gate line 33 is patterned.

A 500 nm thick tantalum (Ta), chromium (Cr), aluminum, etc. is formed on an interlayer insulating film 34 made of an insulating film such as silicon oxide (SiOx) having a thickness of 500 nm. (Al), molybdenum (M
o), a signal line 36 integrated with a drain electrode 36a made of a metal such as tungsten (W), copper (Cu), or a single or a laminated film or alloy film of these metals, and a source electrode 3
7. The auxiliary capacitance electrode 38 is patterned. The drain electrode 36a and the source electrode 37 are electrically connected to the drain region 30c and the source region 30b via the contact holes 40 and 41, and form the pixel TFT 18 that drives the pixel electrode 44. The source electrode 37 is patterned so as to reach from the tact hole 41 to above the gate line 33.

On top of these, silicon nitride (SiN
A transparent protective insulating film 42 which is an inorganic insulating film made of an insulating film such as x) and a colored insulating layer 43 of 3 μm thick green (G), blue (B) and red (R) which is an organic resin insulating film are formed. And a 100 nm-thick indium tin oxide (hereinafter I)
Abbreviated as TO. ) Is formed in a pattern. The previous pixel electrode 44a is connected to the source electrode 37 through a through hole 47 that reaches the source electrode 37 and the auxiliary capacitance electrode 38 through the colored insulating layer 43 and the transparent protective insulating film 42, and is connected to the next pixel electrode 44b.
Are also connected to the auxiliary capacitance electrode 38 through the through hole 47.

On the other hand, a counter substrate 21 is formed by forming a counter electrode 50 made of ITO on a transparent insulating substrate 48 made of transparent glass or the like.
have.

Next, a method of manufacturing the array substrate 20 will be described with reference to FIG. First, the CVD is performed on the transparent insulating substrate 28.
After an amorphous silicon film is deposited to a thickness of 50 nm by a method or the like and annealed at 450 ° C. for 1 hour, XeC1 excimer laser is irradiated to polycrystallize the amorphous silicon film to form a polycrystalline silicon film. Thereafter, the polycrystalline silicon film is patterned by a photo-etching method to form a pattern on the semiconductor layer 30 of the pixel TFT 18 in the display region.

Next, as shown in FIG. 4A, a silicon oxide (SiOx) film to be the gate insulating film 31 is formed to a thickness of 100 nm on the entire surface of the transparent insulating substrate 28 by the CVD method. Subsequently, as shown in FIG. 4B, tantalum (Ta), chromium (Cr), and aluminum (A) are formed on the gate insulating film 31.
l), a metal such as molybdenum (Mo), tungsten (W), copper (Cu) or a simple substance of these metals or a laminated film or an alloy film thereof is formed, and the gate electrode 32 and the gate line 33 are patterned by photoetching. Form. Next, using the gate electrode 32 as a mask, impurities are implanted into both sides of the channel region 30a of the semiconductor layer 30 by ion implantation or ion doping to form a source region 30b and a drain region 30c. For the impurity implantation, P (phosphorus) is implanted at a high concentration of PH ₃ / H ₂ (phosphine / hydrogen) at an acceleration voltage of 80 keV and a dose of 5 × 10 ¹⁵ atoms / cm ² . After that, impurities are activated by annealing the transparent insulating substrate 28.

Further, as shown in FIG.
An interlayer insulating film 34 is formed on the entire surface of the transparent insulating substrate 28 by using the CVD method, and contact holes 40 and 41 reaching the drain region 30c and the source region 30b of the pixel TFT 18 are formed in the interlayer insulating film 34 by the photoetching method. I do. Next, a metal such as tantalum (Ta), chromium (Cr), aluminum (Al), molybdenum (Mo), tungsten (W), copper (Cu), a single element of these metals, or a laminated film or an alloy film thereof is formed to a thickness of 500 nm. Film and Figure 4
As shown in FIG. 3D, patterning is performed into a predetermined shape by a photoetching method to form a signal line 36, a source electrode 37, and an auxiliary capacitance electrode 38 integrated with the drain electrode 36a. As a result, the drain electrode 36a integrated with the signal line 36 via the contact holes 40 and 41 is
0c, and the source electrode 37 is electrically connected to the source region 30b.

Next, as shown in FIG. 4E, silicon nitride (Si) is formed on the entire surface of the transparent insulating substrate 28 by PECVD.
Nx) is formed on the transparent protective insulating film 42, and FIG.
As shown in (f), a first portion 47a of a through hole 47 extending from the source electrode 37 to the auxiliary capacitance electrode 38 on the gate line 33 is formed in the transparent protective insulating film 42 by photoetching. Further, FIG.
As shown in FIG. 4G, a colored insulating layer 43 is formed, and FIG.
As shown in (h), the second portion 47b of the through hole 47 reaching the source electrode 37 and the auxiliary capacitance electrode 38 is formed in the colored insulating layer 43 by photoetching and penetrates the through hole 47. A 100 nm ITO film is formed thereon by sputtering, and is patterned into a predetermined shape by photoetching to form a pixel electrode 44 as shown in FIG. As a result, the previous pixel electrode 44a is electrically connected to the source electrode 37 via the through hole 47, and the next pixel electrode 44b is electrically connected to the auxiliary capacitance electrode 38.

Next, in the counter substrate 21, the counter electrode 5 made of ITO is formed on the transparent insulating substrate 48 by a sputtering method.
0 is formed on the entire surface. Then, alignment films 22 and 23 made of a low-temperature cure type polyimide are printed and applied to the opposing surfaces of the array substrate 20 and the opposing substrate 21, respectively.
After the rubbing process is performed so that the alignment axis becomes 90 ° when the substrates are opposed to each other, the two substrates 20 and 21 are assembled facing each other, formed into cells, and a nematic liquid crystal 24 is injected into the gap therebetween and sealed. Then, the transparent insulating substrates 28, 4 of the two substrates 20, 21
The liquid crystal display element 17 is formed by attaching polarizing plates 26 and 27 to the 8 side.

With this configuration, the pixel electrode 44 in the preceding stage
a and the source electrode 37 and the next stage pixel electrode 44
Since the single through hole 47 per pixel for connection between b and the auxiliary capacitance electrode 38 is single, the colored insulating layer 43
Is a thick film, and it is difficult to process the through hole 47,
The production yield can be improved by halving the number of processes compared to the conventional one. In addition, the through hole 47 is common to the source electrode 37 and the auxiliary capacitance electrode 38, and the processability is increased by increasing the processing size as compared with the conventional case where the source electrode and the auxiliary capacitance electrode are individually formed. Because of the improvement, the display yield such as a point defect due to the formation failure does not occur, and the yield can be improved.

Further, the source electrode 37 is wired so as to extend from the source region 30b in the pixel electrode 44 above the gate line 33, and a through hole 47 having a large processing area is formed not in the pixel electrode 44 but above the gate line 33. By arranging, the gate line 33 also serves as a light shield for the through hole 47, and there is no need to provide a light shield area for the through hole 47 in the pixel electrode 44.
Aperture ratio can be improved, a brighter and higher-contrast display image can be obtained, and display quality can be improved.

The present invention is not limited to the above-described embodiment, and can be modified without departing from the spirit of the invention. The arrangement position of the through-hole is not limited to the position above the gate line, and may be arranged in the pixel electrode.
Further, the shape of the through hole may be a thick film and the portion of the colored insulating layer, which is difficult to process, may be a single part. As in the modification shown in FIGS. 5 and 6, the signal line 36, the source electrode 37, the auxiliary capacitance electrode 3
8, the first through-hole 51 reaching the source electrode 37 above the gate line 33.
And second through hole 52 reaching auxiliary capacitance electrode 38
Are formed respectively, and in the colored insulating layer 43, a single third through hole reaching the source electrode 37 and the auxiliary capacitance electrode 38 above the first through hole 51 and the second through hole 52. By forming the pixel electrode 53, the pixel electrode 44 a in the preceding stage is connected to the source electrode 37 via the first through hole 51 and the third through hole 53, and the second
The pixel electrode 44b at the next stage may be connected to the auxiliary capacitance electrode 38 through the through hole 52 and the third through hole 53. With such a configuration, the number of the third through holes 53 formed in the thick colored insulating layer 43 is one per pixel, so that the production yield can be improved as compared with the conventional device.

The structure of the array substrate is also optional.
The FT semiconductor layer may be formed of amorphous silicon, or the colored insulating layer may also serve as the transparent insulating layer and insulate the source electrode and the auxiliary capacitance electrode. A colored insulating layer may be directly formed thereon.

[0025]

As described above, according to the present invention, the number of through holes in the organic resin insulating film is one per pixel,
By connecting the pixel electrode in the previous stage and the source electrode and connecting the pixel electrode in the next stage and the auxiliary capacitance electrode through this single through-hole, the through-hole in the organic resin insulating film which is thick and difficult to process is formed. The number of holes to be processed can be reduced by half compared with the conventional case, and the production yield of the array substrate can be improved as compared with the conventional case. Furthermore, as compared with the case where the through holes are individually formed, the processing dimensions of the through holes can be enlarged, so that the processability is improved and the display defects such as point defects due to the formation defects can be reduced, thereby improving the production yield. I can do it.

The source electrode extends to above the gate line,
By forming a through-hole for the source electrode above the gate line, the light-shielding region in the pixel electrode can be reduced.
As a result, the aperture ratio of the liquid crystal display element can be improved, a brighter and higher-contrast display image can be obtained, and the display quality can be improved.

[Brief description of the drawings]

FIG. 1 is a partial schematic plan view showing an array substrate according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a through hole portion formed in the array substrate according to the embodiment of the present invention.

FIG. 3 shows a liquid crystal display element according to an embodiment of the present invention.
3 is a schematic sectional view taken along line AA ′ of FIG.

4A to 4C show a manufacturing process of an array substrate according to an embodiment of the present invention, wherein FIG. 4A shows a process of forming a gate insulating film, FIG. 4B shows a process of forming a gate line, and FIG. At the time of membrane,
(D) shows the state when the source electrode and the auxiliary capacitance electrode are formed, and (e)
(F) shows the formation of the first portion of the through hole, (g) shows the formation of the colored insulating film, and (h) shows the formation of the second portion of the through hole. Time,
(I) is a schematic explanatory view showing the time when the pixel electrode is formed.

FIG. 5 is a schematic plan view showing a through hole formed in an array substrate according to another modification of the present invention.

FIG. 6 shows a liquid crystal display device according to another modification of the present invention.
It is a schematic sectional drawing in the BB 'line.

FIG. 7 is a partial schematic plan view showing a conventional array substrate.

FIG. 8 is a schematic cross-sectional view taken along line CC ′ of FIG. 7 showing a conventional liquid crystal display element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 17 ... Liquid crystal display element 18 ... Pixel TFT 20 ... Array substrate 21 ... Opposite substrate 22, 23 ... Alignment film 24 ... Nematic liquid crystal 26, 27 ... Polarizer 28 ... Transparent insulating substrate 30 ... Semiconductor layer 31 ... Gate insulating film 32 ... Gate Electrode 33 ... Gate line 34 ... Interlayer insulating film 36 ... Signal line 37 ... Source electrode 38 ... Auxiliary capacitance electrode 40, 41 ... Contact hole 42 ... Transparent protective insulating film 43 ... Colored insulating film 44 ... Pixel electrode 47 ... Through hole 48 ... Transparent insulating substrate 50: Counter substrate

Claims (5)

[Claims] 1. A gate line on an insulating substrate, a signal line wired to cross the gate line, and a source region and a drain region arranged at an intersection of the gate line and the signal line with at least a channel region interposed therebetween. A semiconductor layer having
A switching element having a gate electrode integral with the gate line, a source electrode connected to the source region, and a drain electrode connected to the drain region; an auxiliary capacitance electrode forming an auxiliary capacitance with the gate line; An organic resin insulating film covering the element and the auxiliary capacitance electrode; and a through hole formed in the organic resin insulating film and arranged in a matrix on a region of the organic resin insulating film surrounded by the gate line and the signal line. An array substrate having a plurality of pixel electrodes connected to the source electrode via a counter electrode; a counter substrate disposed to face the array substrate with a gap therebetween; and a liquid crystal composition sealed between the array substrate and the counter substrate. In the liquid crystal display device, the auxiliary capacitance electrode is provided through a common through hole with the source electrode. An active matrix type wherein the pixel electrode is exposed from a resin insulating film and is connected to another pixel electrode adjacent to the pixel electrode connected to the source electrode with the gate line interposed therebetween through the through hole. Liquid crystal display element. 2. The active matrix type liquid crystal display device according to claim 1, wherein the source electrode extends to a position overlapping the gate line. 3. The active matrix liquid crystal display device according to claim 2, wherein the through hole is formed on a region inside the gate line. 4. An inorganic insulating film is formed between the organic resin insulating film and the source electrode and the storage capacitor electrode, and the source electrode and the storage capacitor electrode are formed through correspondingly formed through holes. 2. The active matrix type liquid crystal display device according to claim 1, wherein the active matrix type liquid crystal display device is exposed from an inorganic insulating film. 5. The active matrix liquid crystal display device according to claim 1, wherein the organic resin insulating film is a colored layer.