JP4031105B2 - Active matrix type liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an active matrix liquid crystal display element in which a pixel electrode is driven by switching elements arranged in a matrix in a liquid crystal display element in which a liquid crystal composition is held between electrode substrates.
[0002]
[Prior art]
In recent years, liquid crystal display elements that achieve high performance and high definition while being thin, light, high density, and large capacity have been developed. In particular, in order to increase the aperture ratio, a transparent pixel electrode is referred to as a thin film transistor (hereinafter referred to as TFT). ) And a liquid crystal display element having a pixel-top structure, which is arranged so as to cover a switching element such as a metal, an insulating film, or a metal (MIM) element. In addition, since there is no need to consider the deviation from the color filter and the production yield can be improved, an active matrix liquid crystal display using an array substrate integrated with a color filter formed by forming an organic resin insulating film under the pixel electrode. The device was being developed.
[0003]
An active matrix type liquid crystal display device using such an array substrate integrated with a color filter has been conventionally 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 that is a color filter, and the pixel electrode 6 is switched 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 the first through hole 12 penetrating the transparent insulating film 10 and the organic resin insulating film 11 to form the gate line 4 and the auxiliary capacitance. The auxiliary capacitance electrode 13 and the next pixel electrode 6 b are electrically connected via a second through hole 14 that penetrates the transparent insulating film 10 and the organic resin insulating film 11.
[0004]
In general, in order to obtain a color filter having sufficient color purity for obtaining a color display, it is necessary to increase the film thickness of the organic resin insulating film constituting the color filter to about 3 μm.
[0005]
[Problems to be solved by the invention]
In a conventional pixel electrode-mounted color filter-integrated array substrate, the previous pixel electrode and source electrode or the next pixel electrode and auxiliary capacitor are passed through two through holes penetrating the organic resin insulating film. Each electrode was electrically connected. On the other hand, the film 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 good color display.
[0006]
For this reason, a through-hole formed through a thick organic resin insulating film is difficult to process, and the through-hole cannot be completely formed, resulting in formation defects, and display defects such as point defects. There has been a problem that the display quality of the display element is lowered. In addition, since two through holes are required per pixel electrode in a thick organic resin insulating film that is difficult to process with conventional array substrates, the yield of the array substrate due to poor formation of through holes is further reduced. It was.
[0007]
In addition, since the organic resin insulating film is thick, the minimum processing size of the through-hole diameter is as large as 10 μm or more, and the liquid crystal display element using such an array substrate has a reduced aperture ratio, which decreases brightness and contrast. There has also been a problem that the display quality is significantly lowered.
[0008]
For this reason, the present invention solves the above-described problem, and when the previous pixel electrode and the source electrode or the subsequent pixel electrode and the auxiliary capacitance electrode are electrically connected through the through hole penetrating the organic resin insulating film. In addition, it prevents the formation of through-holes and prevents the display quality from deteriorating due to display defects such as point defects, and prevents the through-hole from decreasing the aperture ratio of the liquid crystal display area, thereby improving the brightness of the displayed image. An object of the present invention is to provide an active matrix type liquid crystal display device capable of improving display quality and contrast and capable of performing high-quality display.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a gate line on an insulating substrate, a signal line wired so as to cross the gate line, and an intersection of the gate line and the signal line, and at least sandwiching a channel region. A semiconductor layer having a source region and a drain region; a gate electrode integrated with the gate line; a source electrode connected to the source region; a switching element having a drain electrode connected to the drain region; and the gate line and auxiliary capacitance An auxiliary capacitor electrode for forming the switching element and the organic resin insulating film that covers the auxiliary capacitor electrode, and a region on the organic resin insulating film surrounded by the gate line and the signal line, and arranged in a matrix An array base having a plurality of pixel electrodes connected to the source electrode through through holes formed in an organic resin insulating film And a liquid crystal composition sealed between the array substrate and the counter substrate, wherein the auxiliary capacitance electrode is the source electrode The pixel electrode is exposed from the organic resin insulating film through a common through hole and is connected to the pixel electrode connected to the source electrode and the other pixel electrode adjacent to the gate line via the through hole. It is what.
[0010]
With the above configuration, the present invention forms a single through hole that penetrates the organic resin insulating film and reaches the storage capacitor electrode from the source electrode, and the previous pixel electrode and the source electrode or the next through the single through hole. The electrical connection between the pixel electrode of the stage and the auxiliary capacitance electrode is performed, the number of through holes per pixel electrode formed in the thick organic resin insulation film is reduced to one, and the number of processing is reduced. By improving the workability by increasing the through-hole processing dimensions, the manufacturing yield is improved, and point defects due to through-hole formation defects are prevented, thereby improving the display quality of the liquid crystal display element. Further, by arranging the through hole on the gate line, the aperture ratio of the liquid crystal display element is increased, the brightness and contrast of the display image are improved, and the display quality is improved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Reference numeral 17 denotes an active matrix type liquid crystal display element, which is a nematic liquid crystal composition between the array substrate 20 using the pixel TFT 18 as a switching element of the pixel electrode 44 and the counter substrate 21 via the alignment films 22 and 23. The liquid crystal 24 is enclosed. Reference numerals 26 and 27 denote polarizing plates attached to the outside of the array substrate 20 and the counter substrate 21, respectively.
[0012]
The array substrate 20 is formed by patterning a semiconductor layer 30 having a channel region 30a made of polycrystalline silicon, a source region 30b and a drain region 30c made by reducing the resistance of polycrystalline silicon on a transparent insulating substrate 28 made of transparent glass or the like. 400 nm thick tantalum (Ta), chromium (Cr), aluminum (Al), molybdenum (Mo), tungsten (thickness) are formed on the gate insulating film 31 made of silicon oxide (SiOx) or the like having a thickness of 100 nm. W), a metal such as copper (Cu), a single body of these metals, or a laminated film or alloy film thereof, and a gate line 33 formed by integrally forming the gate electrode 32 is patterned.
[0013]
A 500 nm thick tantalum (Ta), chromium (Cr), and aluminum (Al) film are formed on the interlayer insulating film 34 made of an insulating film such as silicon oxide (SiOx) having a thickness of 500 nm. , Molybdenum (Mo), tungsten (W), copper (Cu) or the like, or a single electrode of these metals, or a drain electrode 36a made of a laminated film or alloy film thereof, a signal line 36 integrated with the source electrode 37, and an auxiliary capacitance electrode 38. Is patterned. The drain electrode 36 a and the source electrode 37 are electrically connected to the drain region 30 c and the source region 30 b through the contact holes 40 and 41, thereby forming the pixel TFT 18 that drives the pixel electrode 44. The source electrode 37 is formed in a pattern so as to reach the gate line 33 from the tact hole 41.
[0014]
On top of these, a transparent protective insulating film 42 that is an inorganic insulating film made of an insulating film such as silicon nitride (SiNx), and green (G), blue (B), red, and 3 μm thick organic resin insulating films. A colored insulating layer 43 of (R) is formed, and a pixel electrode 44 made of indium tin oxide (hereinafter abbreviated as ITO) having a thickness of 100 nm is patterned. The preceding pixel electrode 44a is connected to the source electrode 37 through the colored insulating layer 43 and the transparent protective insulating film 42 and through the through hole 47 reaching the source electrode 37 and the auxiliary capacitance electrode 38, and the next pixel electrode 44b. Is also connected to the auxiliary capacitance electrode 38 through the through hole 47.
[0015]
On the other hand, the counter substrate 21 has a counter electrode 50 made of ITO on a transparent insulating substrate 48 made of transparent glass or the like.
[0016]
Next, a method for manufacturing the array substrate 20 will be described with reference to FIG. First, an amorphous silicon film having a thickness of 50 nm is deposited on the transparent insulating substrate 28 by CVD or the like, and furnace annealing is performed at 450 ° C. for 1 hour, followed by irradiation with XeC1 excimer laser to polycrystallize the amorphous silicon film. A film is formed. Thereafter, the polycrystalline silicon film is patterned by a photoetching method to pattern the semiconductor layer 30 of the pixel TFT 18 in the display region.
[0017]
Next, as shown in FIG. 4A, a silicon oxide (SiOx) film to be the gate insulating film 31 is formed to 100 nm on the entire surface of the transparent insulating substrate 28 by the CVD method. Subsequently, as shown in FIG. 4B, a metal such as tantalum (Ta), chromium (Cr), aluminum (Al), molybdenum (Mo), tungsten (W), copper (Cu) or the like is formed on the gate insulating film 31. A single metal such as a single layer or a laminated film thereof or an alloy film is formed, and the gate electrode 32 and the gate line 33 are patterned by a photoetching method. 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. The impurity is implanted by, for example, implanting P (phosphorus) at a high concentration by PH ₃ / H ₂ (phosphine / hydrogen) at an acceleration voltage of 80 keV and a dose of 5 × 10 ¹⁵ atoms / cm ² . Thereafter, the transparent insulating substrate 28 is annealed to activate the impurities.
[0018]
Further, as shown in FIG. 4C, an interlayer insulating film 34 is formed on the entire surface of the transparent insulating substrate 28 using, for example, PECVD, and the drain region 30c of the pixel TFT 18 is formed on the interlayer insulating film 34 by photoetching. Contact holes 40 and 41 reaching the source region 30b are formed. 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 alloy film thereof is formed to a thickness of 500 nm. 4D, and patterned into a predetermined shape by a photoetching method as shown in FIG. 4D, to form a signal line 36 integrated with the drain electrode 36a, a source electrode 37, and an auxiliary capacitance electrode 38. Thereby, the drain electrode 36a integrated with the signal line 36 is electrically connected to the drain region 30c via the contact holes 40 and 41, and the source electrode 37 is electrically connected to the source region 30b.
[0019]
Next, as shown in FIG. 4E, a transparent protective insulating film 42 made of silicon nitride (SiNx) is formed on the entire surface of the transparent insulating substrate 28 by PECVD, and photoetching is performed as shown in FIG. A first portion 47 a of a through hole 47 reaching 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 the method. Further, a colored insulating layer 43 is formed by PECVD as shown in FIG. 4G, and reaches the source electrode 37 and the auxiliary capacitance electrode 38 on the colored insulating layer 43 by photoetching as shown in FIG. 4H. A second portion 47 b of the through hole 47 is formed and penetrates the through hole 47. On this, ITO is deposited to a thickness of 100 nm by a sputtering method, and patterned into a predetermined shape by a photoetching method to form a pixel electrode 44 as shown in FIG. As a result, the previous pixel electrode 44 a is electrically connected to the source electrode 37 through the through hole 47, and the next pixel electrode 44 b is electrically connected to the auxiliary capacitance electrode 38.
[0020]
Next, in the counter substrate 21, a counter electrode 50 made of ITO is formed on the entire surface of the transparent insulating substrate 48 by sputtering. Then, alignment films 22 and 23 made of low-temperature cured polyimide are printed on the opposing surfaces of the array substrate 20 and the counter substrate 21, respectively, and a rubbing process is performed so that the alignment axis is 90 ° when the substrates 22 and 23 are opposed to each other. After that, both the substrates 20 and 21 are assembled to face each other to form a cell, and a nematic liquid crystal 24 is injected into the gap to be sealed. Then, the liquid crystal display element 17 is formed by attaching the polarizing plates 26 and 27 to the transparent insulating substrates 28 and 48 of both the substrates 20 and 21.
[0021]
With this configuration, there is a single through-hole 47 per pixel for connecting the pixel electrode 44a in the previous stage and the source electrode 37 and for connecting the pixel electrode 44b in the next stage and the auxiliary capacitance electrode 38. Therefore, even if the colored insulating layer 43 is a thick film and it is difficult to process the through hole 47, the manufacturing yield can be improved by halving the number of processing compared to the conventional method. In addition, the through-hole 47 is common to the source electrode 37 and the auxiliary capacitance electrode 38, and the workability is increased by increasing the processing size as compared to the case where the source electrode and the auxiliary capacitance electrode are individually formed as in the prior art. Since it can be improved, display defects such as point defects due to formation defects do not occur, and the yield can be improved.
[0022]
Further, the source electrode 37 is wired so as to extend from the source region 30 b in the pixel electrode 44 to above the gate line 33, and the through hole 47 having a large processing area is disposed not in the pixel electrode 44 but above the gate line 33. As a result, the gate line 33 also serves as light shielding for the through hole 47, and it is not necessary to provide a light shielding region for the through hole 47 in the pixel electrode 44. Therefore, the aperture ratio of the liquid crystal display element 17 can be improved and brighter. A display image with good contrast can be obtained and display quality can be improved.
[0023]
The present invention is not limited to the above embodiment, and can be changed without changing the gist of the present invention. For example, a single through hole formed through a colored insulating layer and a transparent protective insulating film. The arrangement position is not limited to the upper side of the gate line, and may be arranged in the pixel electrode. Further, the through hole may be a thick film that has a single color insulating layer portion that is difficult to process, and the signal line 36, the source electrode 37, the auxiliary capacitance electrode, as in the modification shown in FIGS. In the transparent protective insulating film 42 on 38, a first through hole 51 reaching the source electrode 37 and a second through hole 52 reaching the auxiliary capacitance electrode 38 are formed above the gate line 33, respectively. In the colored insulating layer 43, by forming a single third through hole 53 that reaches the source electrode 37 and the auxiliary capacitance electrode 38 above the first through hole 51 and the second through hole 52, The previous pixel electrode 44 a is connected to the source electrode 37 via the first through hole 51 and the third through hole 53, and the next pixel electrode is connected via the second through hole 52 and the third through hole 53. 4b 2008 may be connected to the storage capacitor electrode 38. If formed in this way, the number of third through holes 53 formed in the thick colored insulating layer 43 is one per pixel, so that the manufacturing yield can be improved as compared with the conventional device.
[0024]
The structure of the array substrate is arbitrary, and the semiconductor layer of the pixel TFT may be formed of amorphous silicon. The colored insulating layer also serves as the transparent insulating layer, and insulates the source electrode and the auxiliary capacitance electrode. A colored insulating layer may be directly formed on the source electrode and the auxiliary capacitance electrode without using a layer.
[0025]
【The invention's effect】
As described above, according to the present invention, the number of through holes in the organic resin insulating film is one per pixel, and the connection between the pixel electrode and the source electrode in the previous stage and the next stage through the single through hole. By connecting the pixel electrode and the auxiliary capacitor electrode, the number of through-holes in the thick organic resin insulating film that is difficult to process can be halved compared to the conventional one, and the manufacturing yield of the array substrate can be improved compared to the conventional one. . Furthermore, compared to the case where through holes are individually formed, the processing dimensions of the through holes can be expanded, so that the workability is improved and display defects such as point defects due to formation defects can be reduced, which improves the manufacturing yield. I can plan.
[0026]
Further, the light shielding region in the pixel electrode can be reduced by extending the source electrode to above the gate line and forming a through hole with respect to the source electrode above the gate line. Thereby, the aperture ratio of the liquid crystal display element can be improved, and a brighter and higher contrast display image can be obtained, thereby improving the display quality.
[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.
3 is a schematic cross-sectional view taken along the line AA ′ of FIG. 2 showing the liquid crystal display element according to the embodiment of the present invention.
4A and 4B show a manufacturing process of an array substrate according to an embodiment of the present invention, in which FIG. 4A shows the gate insulating film formation, FIG. 4B shows the gate line formation, and FIG. 4C shows the interlayer insulating film formation. (D) when forming the source electrode and auxiliary capacitance electrode, (e) when forming the transparent protective insulating film, (f) when forming the first part of the through hole, and (g) When forming a colored insulating film, (h) is a schematic explanatory diagram showing the second partial formation of the through hole, and (i) is a schematic explanatory view showing the pixel electrode formation.
FIG. 5 is a schematic plan view showing a through hole portion formed in an array substrate according to another modification of the present invention.
6 is a schematic cross-sectional view taken along line BB ′ of FIG. 5 showing a liquid crystal display device according to another modification of the present invention.
FIG. 7 is a partial schematic plan view showing a conventional array substrate.
8 is a schematic cross-sectional view taken along the line CC ′ of FIG. 7 showing a conventional liquid crystal display element.
[Explanation of symbols]
17 ... Liquid crystal display element 18 ... Pixel TFT
DESCRIPTION OF SYMBOLS 20 ... Array substrate 21 ... Counter substrate 22, 23 ... Orientation film 24 ... Nematic liquid crystal 26, 27 ... Polarizing plate 28 ... Transparent insulating substrate 30 ... Semiconductor layer 31 ... Gate insulating film 32 ... Gate electrode 33 ... Gate line 34 ... Interlayer insulation Film 36 ... Signal line 37 ... Source electrode 38 ... Auxiliary capacitance electrodes 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)

A semiconductor layer having a source region and a drain region sandwiched between a gate line, a signal line wired so as to intersect the gate line, and at least an intersection of the gate line and the signal line, with a channel region interposed therebetween, 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, and the switching An organic resin insulation film covering the element and the auxiliary capacitance electrode, and a through hole formed in the organic resin insulation film in a matrix form in a region surrounded by the gate line and the signal line on the organic resin insulation film An array substrate having a plurality of pixel electrodes connected to the source electrode via
A counter substrate disposed opposite to the array substrate with a gap therebetween;
In a liquid crystal display device comprising a liquid crystal composition sealed between the array substrate and the counter substrate,
The auxiliary capacitance electrode is exposed from the organic resin insulating film through a common through hole with the source electrode, and is connected to the pixel electrode connected to the source electrode and the other pixel electrode adjacent to the gate line An active matrix type liquid crystal display element connected through the through-hole. 2. The active matrix liquid crystal display device according to claim 1, wherein the source electrode extends to a position overlapping with the gate line. 3. The active matrix type liquid crystal display device according to claim 2, wherein the through hole is formed on a region inside the gate line. An inorganic insulating film is formed between the organic resin insulating film, the source electrode, and the auxiliary capacitance electrode, and the source electrode and the auxiliary capacitance electrode are exposed from the inorganic insulating film through through holes formed correspondingly. The active matrix type liquid crystal display element according to claim 1, wherein: 5. The active matrix type liquid crystal display element according to claim 1, wherein the organic resin insulating film is a colored layer.

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