JP3540639B2 - Liquid crystal display - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure of an electrode of a liquid crystal display device provided with a switching element such as a thin film transistor.
[0002]
[Prior art]
Active matrix liquid crystal display device, a plurality of pixels electrodes for applying a voltage to the liquid crystal layer is formed in a matrix. In order to drive the pixel electrodes to the selected択的, switching element is connected is formed on the active matrix substrate with the pixel electrodes.
[0003]
JP-A-7-128687, as shown in FIG. 6, the switching element 1 provided in a matrix, a scanning line 3 connecting the gate electrode of the switching element 1 in each column, the switching element a pixel electrode 8 connected to the drain electrode of the reference signal line 6 connecting the source electrodes of the switching elements 1 in each column, the insulation protects the scanning lines 3 or the reference signal line 6 is gate electrode interpolar pixel substrate 22 having the gate insulating film, a counter electrode opposed to each pixel electrode 8, a counter substrate 23 having a display signal line 24 connecting the counter electrode in each row, the counter substrate 23 and the pixel substrate A liquid crystal display device including a liquid crystal layer 21 sealed between the liquid crystal display devices 22 is disclosed.
[0004]
Since the scanning line 3 and the reference signal line 6 do not cross on the same substrate, the liquid crystal display device having such a structure has a feature that short-circuiting and disconnection are unlikely to occur. The amount of investment in production equipment can be greatly reduced. However, in order to be kept defective constant of the gate electrodes in the following order of magnitude%, aluminum or, in the case of using the tantalum to the scan line material, subjected to anodic oxidation of these metals, a two-layer gate insulating film structure By doing so, the yield was improved.
[0005]
[Problems to be solved by the invention]
However, in the structure described in Japanese Patent Application Laid-Open No. 7-128687, the third terminal from which a current is output from the switching element is made common to the N-type semiconductor substrate, or arranged as a common electrode on a transparent substrate. For this reason, there is a problem that the aperture ratio of the transmission type liquid crystal display device is reduced, or the aperture ratio is reduced due to the provision of the common electrode.
[0006]
The present invention relates to a switching element 1 provided in a matrix, a scanning line 3 connecting a gate electrode 2 of the switching element 1 for each column, and a pixel electrode 8 connected to a drain electrode 7 of the switching element 1. And a reference signal line 6 for connecting the source electrode 4 of the switching element 1 for each column, and a gate insulating film 9 for insulating and protecting the scanning line 3 or the gate electrode 2 or the reference signal line 6 consisting When a counter electrode opposed to each of the pixel electrodes 8, and a counter substrate having a display signal line connecting the counter electrode for each row, and the counter substrate and a liquid crystal layer sealed between the pixel substrate in the liquid crystal display device, and to realize a liquid crystal display device with high aperture ratio without protruding the switching element 1 without loss of wiring.
[0007]
[Means for Solving the Problems]
In the liquid crystal display device according to the first aspect of the present invention, the switching elements provided in a matrix, the scanning lines connecting the gate electrodes of the switching elements for each column, and the drain electrodes of the switching elements are connected. A pixel substrate having a pixel electrode, a reference signal line connecting a source electrode of the switching element for each column, a gate insulating film for insulating and protecting the scan line or the gate electrode or the reference signal line, a counter electrode opposed to each consists of a counter substrate having a display signal line connecting the counter electrode in each row, is sealed between the counter substrate and the pixel substrate and a liquid crystal layer, the liquid crystal display device, the scanning lines and the gate electrodes are connected alternately in a straight line and the gate electrode is minor than the width of the scan line, by applying a voltage to said gate electrode, said drain electrode and said source Between the electrode current, characterized in that the flow in the width direction of the gate electrode.
[0008]
In the liquid crystal display device according to the second aspect of the present invention, the switching elements provided in a matrix, the scanning lines connecting the gate electrodes of the switching elements for each column, and the drain electrodes of the switching elements are connected. A pixel substrate having a pixel electrode, a reference signal line connecting a source electrode of the switching element for each column, a gate insulating film for insulating and protecting the scan line or the gate electrode or the reference signal line, a counter electrode opposed to each consists of a counter substrate having a display signal line connecting the counter electrode in each row, is sealed between the counter substrate and the pixel substrate and a liquid crystal layer, the liquid crystal display device, The reference signal line has a structure of two or more layers including a first layer made of the same material as the scanning line and a second layer made of the same material as the pixel electrode. Part of the side and the A step portion of the gate insulating film is interposed in the layer, and the scanning line side of the second layer covers the step portion of the gate insulating film, and an end of the first layer on the scanning line side. The first layer and the second layer extend up to a plane between the scan line and the upper and lower contacts of the first layer and the second layer at the center of the first layer .
[0009]
According to a third aspect of the present invention, in the liquid crystal display device, the switching elements provided in a matrix, the scanning lines connecting the gate electrodes of the switching elements for each column, and the drain electrodes of the switching elements are connected. A pixel substrate having a pixel electrode, a reference signal line connecting a source electrode of the switching element for each column, a gate insulating film for insulating and protecting the scan line or the gate electrode or the reference signal line, A liquid crystal display device comprising a counter electrode having a display signal line connecting the counter electrode for each row, and a liquid crystal layer sealed between the counter substrate and the pixel substrate. The reference signal line has a structure of two or more layers, that is, a first layer made of the same material as the scanning line and a second layer made of the same material as the pixel electrode. Opposite one layer The gate insulating film is covered with a stepped portion, and the opposite side of the second layer with respect to the scanning line is located on the middle side of the plane of the first layer with respect to the first layer. wherein the substantially matches to Rukoto with the end of the step portion.
[0010]
The liquid crystal display device according to claim 4 of the present invention is characterized in that a connecting line for connecting a plurality of the reference signal line to the pixel on the substrate.
[0011]
The liquid crystal display device according to claim 5 of the present invention, in one direction of the pixel electrode with respect to the corresponding said scan line adjacent and the corresponding scan line, in the direction the same direction, corresponding the reference The signal lines are adjacent to each other. The liquid crystal display device according to claim 6 of the present invention is characterized in that the gate insulating film is formed of a single layer not including an anodic oxide film.
[0012]
Hereinafter, the operation of the above configuration will be described. In an active matrix liquid crystal display device according to a first aspect of the present invention, by providing a constriction in the gate electrode on the line of the scanning lines, thereby improving the aperture ratio of the liquid crystal display device using the gate electrode narrower than the scanning line be able to.
[0013]
Further, in the active matrix type liquid crystal display device according to the second or third aspect of the present invention, the line width of the reference signal line is made smaller than the line width of the scanning line, so that the aperture ratio can be improved. Further, even if less than査線width run the reference signal line width, less likely to cause disconnection failure, the resistance value even by reducing the wiring width can be reduced, thereby improving the aperture ratio. In the liquid crystal display device according to a fourth aspect of the present invention, a connection line connecting a plurality of reference signal lines is provided on the pixel substrate, so that the entire resistance value including the routing portion of the reference signal line is reduced. Reduces the wiring width and improves the aperture ratio.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below.
(Embodiment 1) FIGS. 1 and 2 show a structure around a switching element 1 of a liquid crystal display device of the present invention. FIG. 2 shows a cross section taken along line AA ′ of FIG. A scanning line connecting between the gate electrodes 2 of each column with respect to a three-terminal switching element 1 such as an amorphous silicon semiconductor provided in a matrix and a gate electrode 2 of N-type microcrystalline silicon of the switching element 1 3 are disposed. A reference signal line 6 is connected to a source electrode 4 made of N-type microcrystalline silicon, which is another terminal of each column of the switching element 1 via a connection line 5 made of ITO. A pixel electrode 8 made of ITO having a thickness of 180 nm is connected to a drain electrode 7 serving as another terminal via a shortest extension line 8a of the pixel electrode.
[0015]
The scanning line 3 and the reference signal line 6 are usually made of the same material, such as a tantalum-based or aluminum-based metal material. However, the present invention is not limited to this. In the first embodiment of the present invention, a prototype was manufactured with a three-layer structure of TaN / Ta / TaN, and the thickness of each layer was set to 60 nm / 260 nm / 40 nm.
[0016]
In the first embodiment, the amorphous silicon semiconductor layer 10 is formed on the gate electrode 2 via the gate insulating film 9 made of a single layer of a 200 nm-thick silicon nitride film. It has been found that, unlike the conventional liquid crystal display device, it is desirable not to form an anodic oxide film on the Ta film as the gate insulating film 9.
[0017]
The reason is as shown in the following (1) to (3) . (1) The process can be simplified. (2) This structure does not require an anodic oxide film because defects such as disconnection hardly occur. (3) Since about half the thickness of the anodic oxide film can be used as the electrode layer, the wiring resistance can be reduced. If you do not use as an electrode layer, in order that can further small Kude the line width of the wiring, it is possible to further increase the aperture ratio of the liquid crystal display device. Further, in order to realize a liquid crystal display device having such a structure, a tapered angle of the side wall portion of the scanning line 3 is formed in a gentle shape of 10 ° to 30 °, and the step coverage of the film stacked on the upper portion is reduced . it is necessary to conscious as well done.
[0018]
For the purpose of further shortening the process, as shown in FIG. 2, a three-layer external pattern of a gate insulating film 9, a semiconductor layer 10 made of amorphous silicon, and N-type microcrystalline silicon forming source electrode 4 and drain electrode 7 is formed. Can be formed at once in one process. Further, the source electrode 4 and the drain electrode 7 can be separated by using a pattern made of the upper layer ITO as a mask. FIG. 2 shows the first embodiment in which the center of the gate electrode 2 and the center of the scanning line 3 are arranged on the same straight line, but the condition that the width of the gate electrode 2 is smaller than the width of the scanning line 3 is satisfied. Then, in order to achieve the object, it is not always necessary to arrange the patterns so that each center is on the same straight line.
[0019]
Thus, the switching elements 1 provided in a matrix, the scanning lines 3 connecting the gate electrodes 2 of the switching elements 1 for each column, and the pixel electrodes 8 connected to the drain electrodes 7 of the switching elements 1 A pixel substrate having a reference signal line 6 connecting the source electrode 4 of the switching element 1 for each column, and a gate insulating film 9 for insulating and protecting the scanning line 3 or the gate electrode 2 or the reference signal line 6; composed of a counter electrode opposed to each pixel electrode 8, and a counter substrate having a display signal line connecting the counter electrode for each row, and a liquid crystal layer sealed between the the counter substrate and the pixel substrate, a liquid crystal display The device was prototyped as a 15-inch XGA display.
[0020]
As a result, a yield of 90% or more is obtained as the yield of the pixel substrate, and the estimated cost estimated from this result can achieve a significant cost reduction of about 30 to 40% compared to the conventional active matrix substrate. I got some insight. In the above prototype, the length of the gate electrode 2 is 10 μm, the width is 9 μm, the width of the scanning line 3 is 15 μm, the width of the reference signal line 6 is 15 μm, and the gap between the reference signal line 6 and the scanning line 3 is 15 μm . did. In order to further improve the aperture ratio, the wiring width can be further reduced by using a copper-based wiring material having a low specific resistance. In this case, in particular, the gap between the reference signal line 6 and the scanning line 3 can be reduced to 15 μm or less. As described above, the gate electrode 2 on the scanning line 3 is narrowed to have a different width, and the gate electrode 2 is made thinner than the scanning line 3, thereby eliminating the optical loss generated from the wiring portion and reducing the aperture ratio. It could be realized with improved liquid Akirahyo shows apparatus.
[0021]
As described above, unlike the conventional liquid crystal display device, it is desirable not to form an anodic oxide film as the gate insulating film 9 from the viewpoint of improving the aperture ratio. However, the anodic oxide film may be part of the gate insulating film. . Incidentally, a counter substrate of a liquid crystal display device shown in Embodiment 1, using the counter substrate hardly different structure shown in FIG.
[0022]
(Embodiment 2) FIGS. 3 and 4 show the structure around the switching element 1 of the liquid crystal display device of the present invention. FIG. 4 is a sectional view taken along line AA ′ of FIG. A scanning line 3 is connected to a gate electrode 2 of a three-terminal switching element 1 made of an amorphous silicon semiconductor or the like provided in a matrix in substantially the same straight line, and a source electrode 4 of each column of the switching element 1 is connected to a reference signal line. 6 is connected, and a pixel electrode 8 is connected to a drain electrode 7 which is another terminal of each of the switching elements 1.
[0023]
In the second embodiment, on one side of the reference signal line 6, via a gate insulating film 9 made of silicon nitride, the scanning lines 3 are close. Further, an adjacent pixel electrode 8b is close to the other side of the reference signal line 6 .
[0024]
The reference signal line 6 is made of the same material as the scanning line 3, and has a three-layer structure of TaN / Ta / TaN and a lower-layer reference signal line 11 made of a single-layer or multi-layer metal film of Ta-based or Al-based , 8 has a structure of two or more upper reference signal lines 12 made of a transparent conductive film such as ITO. A gate insulating film 9 is interposed in a part of the upper reference signal line 12 and a part of the lower reference signal line 11, and an upper and lower contact is made at the center side of the reference signal line 6. One side 12a of the upper-layer reference signal line 12 extends between a plane between one end 11a of the lower-layer reference signal line 11 and the scanning line 3, and the step portion 9a of the gate insulating film 9 on one side is connected to the upper-layer reference signal line 11. The signal line 12 is covered. The other side 12b of the upper reference signal line 12 is in the middle side of the plane of the other end 11b by Ri lower layer reference signal line 11 of the lower reference signal line 11, the step portion 9b of the other side of the gate insulating film 9 And is arranged so as to substantially coincide with the end 9 c of the gate insulating film 9. Further, a protective film 13 made of silicon nitride having a thickness of 200 nm is formed on the periphery of all the pixel electrodes 8 and 8b including the adjacent one and on the upper part of the reference signal line 6 so as to protect the wiring and to prevent short-circuit due to foreign matter. Was.
[0025]
As described above, one side 12a of the upper-layer reference signal line 12 extends to between the plane between the one end 11a of the lower-layer reference signal line 11 and the scanning line 3 , so that the wiring resistance is reduced and the source electrode 4 Short-circuit defects generated between the reference signal lines 6 were significantly reduced. The other side 12b of the upper reference signal line 12 is in the middle side of the plane of the other side 11b by Ri lower layer reference signal line 11 of the lower reference signal line 11, on the other side of the gate insulating film 9 step The portion 9b is not covered, and is arranged substantially coincident with the end 9c of the gate insulating film 9 . With this arrangement, when forming the pattern, the upper layer of the ITO of the two positions of the stepped portions 16a, due to the higher etch rate in 16b, to prevent the short circuit between the adjacent pixel electrodes 8 b effect Was observed.
[0026]
Further, as shown in FIG. 5, it is desirable to provide one to several connecting lines 14 for connecting the hundreds of reference signal lines 6 to each other. In the second embodiment, the upper and lower contacts are made at the center of the reference signal line 6. One side 12a of the upper-layer reference signal line 12 extends between a plane between one end 11a of the lower-layer reference signal line 11 and the scanning line 3, and the step portion 9a of the gate insulating film 9 on one side is connected to the upper-layer reference signal line 11. The signal line 12 is covered. The other side 12b of the upper reference signal line 12 is in the middle side of the plane of the other end 11b by Ri lower layer reference signal line 11 of the lower reference signal line 11, the step portion 9b of the other side of the gate insulating film 9 And is arranged so as to substantially coincide with the end 9 c of the gate insulating film 9. Further, a protective film 13 made of silicon nitride having a thickness of 200 nm was formed on the peripheral portion of the pixel electrode 8b including the adjacent region and on the reference signal line 6 to protect the wiring and to prevent short-circuit due to foreign matter.
[0027]
By providing one to several short-circuit lines (connection lines) 14 for connecting several hundred reference signal lines 6 to each other, the wiring resistance of the reference signal lines 6 can be significantly reduced. However, in order to prevent a short-circuit failure at the intersection between the short-circuit line 14 and the scanning line 3, it is desirable that the number of short-circuit lines 14 be several or less. The signal input terminal 17 from an external reference signal line 6 is about one point with respect to the scan signal input terminal 19 from the outside of a few ten or more scanning lines 3, provided sequence of scan signal input terminals 19, external components argument of the connection between the terminals collectively processed by the terminal 17 of the reference signal line 6 and the terminal 19 of the scanning line 3, to ensure the connection pitch of the scan signal input terminal 19 of the scanning line 3, and the reference signal line 6 The wiring wiring resistance has been reduced.
[0028]
In the second embodiment, the width of the reference signal line 6 is 10 μm, the gap between the reference signal line 6 and the scanning line 3 is 10 μm, and the gap between the reference signal line 6 and the adjacent pixel electrode 8 b is 5 μm. , The width of the reference signal line 6, the gap between the reference signal line 6 and the scanning line 3, and the gap between the reference signal line 6 and the adjacent pixel electrode 8b are made smaller than in the first embodiment, and the pixel electrode 8 could be enlarged. With the design dimensions as described above, the reference signal line 6 is made narrower than the scanning line 3 to eliminate wiring loss, and a 15-inch XGA liquid crystal display device is prototyped. As a result, the pixel substrate yield is 90%. above is obtained, Traditional achieving significant cost reduction of about 30-40% with respect to manufacturing cost of the active matrix substrate could be further aperture rate greatly improved.
[0029]
【The invention's effect】
As described above, in the active matrix liquid crystal display device according to the first aspect of the present invention, by providing a constriction in the gate electrode on the line of the scanning line, the gate electrode is narrower than the scanning lines, the liquid crystal display There is an effect that the aperture ratio of the device can be improved. Further, in the active matrix type liquid crystal display device according to the second aspect of the present invention, there is an effect that the line width of the reference signal line can be reduced and the aperture ratio can be improved. Further, in the active matrix type liquid crystal display device according to the second or third aspect of the present invention, there is an effect that the line width of the reference signal line is made smaller than the line width of the scanning line to improve the aperture ratio.
[0030]
The liquid crystal display device according to claim 2 or claim 3, wherein the present invention, be smaller than the査線width run the reference signal line width, without causing a disconnection failure, both the resistance value and the wiring width because can be reduced, it is Rukoto further improve the aperture ratio. In the liquid crystal display device according to the fourth aspect of the present invention, by providing a connection line connecting a plurality of reference signal lines on the pixel substrate, the entire resistance value including the routing portion of the reference signal line is reduced, Even if the wiring width is reduced, the effect of improving the aperture ratio can be obtained. In the liquid crystal display device according to the fifth aspect of the present invention, since the gate electrode and the reference signal line are connected at the shortest distance , the connection line and the reference signal line can be made the minimum size, thereby improving the aperture ratio. To play.
[0031]
In the liquid crystal display device according to claim 6 of the present invention, since the gate insulating film is formed of a single layer not including the anodic oxide film, the process can be simplified. Further, since about half the thickness of the anodic oxide film can be used as the electrode layer, it is possible to reduce the wiring resistance. When not used as an electrode layer, the line width of the wiring can be further reduced, so that the aperture ratio of the liquid crystal display device can be further increased.
[Brief description of the drawings]
FIG. 1 is a plan view showing the vicinity of a switching element according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA 'of FIG.
FIG. 3 is a plan view showing the vicinity of a switching element according to a second embodiment of the present invention.
FIG. 4 is a sectional view taken along line AA ′ of FIG. 3;
FIG. 5 is a plan view showing an example of a pattern of a reference signal line according to the present invention.
FIG. 6 is a perspective view showing a configuration of an improved liquid crystal display device according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Switching element 2 Gate electrode 3 Scanning line 4 Source electrode 5 Connection line 6 Reference signal line 7 Drain electrode 8 Pixel electrode 8a Shortest extension line 9 Gate insulating film
9a Step on One Side of Gate Insulating Film
9b Step portion on the other side of gate insulating film
9c Edge 10 of gate insulating film Semiconductor layer 11 Lower reference signal line
11a One end of lower layer reference signal line
11b The other end of the lower-layer reference signal line 12 The upper-layer reference signal line
12a One side of upper layer reference signal line
The other side 13 protective film 14 connecting wire 16a stepped portion component 16b stepped portions min 17 signal input terminal 12b upper reference signal line
19 Scanning signal input terminal
21 Liquid crystal layer
22 Pixel substrate
23 Counter substrate
24 Display signal line

Claims (6)

A switching element provided in a matrix, a scanning line connecting a gate electrode of the switching element for each column, a pixel electrode connected to a drain electrode of the switching element, and a source electrode of the switching element are arranged in each column. A reference signal line connected to each pixel, a pixel substrate having a gate insulating film for insulating and protecting the scanning line or the gate electrode or the reference signal line,
A counter substrate having a counter electrode opposed to each of the pixel electrodes, the display signal lines for connecting the counter electrode in each row,
In a liquid crystal display device, comprising a liquid crystal layer sealed between the counter substrate and the pixel substrate,
The scanning lines and the gate electrodes are connected alternately in a straight line and the gate electrode is minor than the width of the scanning lines,
A liquid crystal display device wherein a current flows between the drain electrode and the source electrode in the width direction of the gate electrode by applying a voltage to the gate electrode . A switching element provided in a matrix, a scanning line connecting a gate electrode of the switching element for each column, a pixel electrode connected to a drain electrode of the switching element, and a source electrode of the switching element are arranged in each column. A reference signal line connected to each pixel, a pixel substrate having a gate insulating film for insulating and protecting the scanning line or the gate electrode or the reference signal line,
A counter substrate having a counter electrode opposed to each of the pixel electrodes, the display signal lines for connecting the counter electrode in each row,
In a liquid crystal display device, comprising a liquid crystal layer sealed between the counter substrate and the pixel substrate,
The reference signal line has a structure of two or more layers including a first layer made of the same material as the scanning line and a second layer made of the same material as the pixel electrode.
A step portion of the gate insulating film is interposed between a part of the second layer on the scanning line side and the first layer;
The scanning line side of the second layer covers the step portion of the gate insulating film, and extends to between a plane between the scanning line side end of the first layer and the scanning line;
The liquid crystal display device, wherein the first layer and the second layer are in vertical contact at the center of the first layer . A switching element provided in a matrix, a scanning line connecting a gate electrode of the switching element for each column, a pixel electrode connected to a drain electrode of the switching element, and a source electrode of the switching element are arranged in each column. A reference signal line connected to each pixel, a pixel substrate having a gate insulating film for insulating and protecting the scanning line or the gate electrode or the reference signal line,
A counter electrode facing each of the pixel electrodes, a counter substrate having a display signal line connecting the counter electrode for each row,
In a liquid crystal display device, comprising a liquid crystal layer sealed between the counter substrate and the pixel substrate,
The reference signal line has a structure of two or more layers including a first layer made of the same material as the scanning line and a second layer made of the same material as the pixel electrode.
The opposite side of the first layer with respect to the scanning line is covered with a step portion of the gate insulating film,
The opposite side of the second layer with respect to the scanning line is located on the middle side of the plane of the first layer with respect to the first layer, and substantially coincides with the end of the step portion of the gate insulating film. Characteristic liquid crystal display device. To the pixel on the substrate, a liquid crystal display device according to any one of claims 1 3, characterized in that a connecting line for connecting a plurality of the reference signal line. In one direction of the pixel electrode with respect to the corresponding said scan line adjacent and the corresponding scan line, in the direction the same direction, corresponding the reference signal lines, characterized in that adjacent claim 1 5. The liquid crystal display device according to any one of items 1 to 4 . 2. The liquid crystal display device according to claim 1, wherein said gate insulating film is formed of a single layer not including an anodic oxide film.

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