KR100438964B1 - Liquid crystal display device and a fabrication method thereof, particularly with regards to increasing an opening ratio without using an additional mask by employing storage electrodes formed on the same layer with the same conductive material as a signal line - Google Patents

Abstract

PURPOSE: An LCD device and a fabrication method thereof are provided to form storage electrodes with the same wiring material as a signal line, and to connect the storage electrodes with a shielding layer formed with the same wiring material as a scanning line, or to connect the electrodes with a transparent line, thereby increasing an opening ratio without a deposition process or a mask. CONSTITUTION: Storage electrodes(43X) formed with the same conductive material as a signal line(43L) are positioned in every pixel at the same layer of the signal line(43L) located at a upper side of a scanning line(41L). The storage electrodes(43X) of each pixel are connected to a shielding layer(41X) to be commonly connected with external electrodes. A signal line wiring material and a scanning line wiring material are insulated by the first insulating film(42), while the signal line wiring material and pixel electrodes are insulated by the second insulating film(46).

Description

Liquid crystal display device and manufacturing method thereof

The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly to a liquid crystal display device having a structure for improving an aperture ratio and a manufacturing method thereof.

A typical liquid crystal display device has a thin film transistor array substrate (hereinafter referred to as a bottom plate) and a color filter substrate (hereinafter referred to as a top plate), and liquid crystal is filled between the two substrates. In the lower panel, pixels (PIXEL: Picture Elements) having a thin film transistor as a switching element and a pixel electrode connected to the drain electrode of the thin film transistor as a basic unit are arranged vertically and horizontally, and the gate electrodes of the thin film transistors are connected to each other A plurality of signal lines for connecting the plurality of scanning lines and the source electrodes of the thin film transistors along one direction are formed. A color filter is formed on the upper panel so as to have one of red, green and blue (RGB) colors corresponding to each pixel.

In a liquid crystal display device having such a structure, there is a part that can not completely control the light transmitted from the back light due to the structure of the signal line, the thin film transistor, and the pixel electrode provided on the lower plate. Thus, as shown in Fig. 1, the area between the color filters (not shown) of the upper plate 14, that is, the signal line 11 of the lower panel 10, A black matrix 13 formed of chromium is formed. A protective film is formed on the surface of the color filter and the light-shielding film, and a common electrode for applying an electric field to the liquid crystal corresponding to the pixel electrode 12 is formed on the protective film.

However, in the conventional liquid crystal display device in which the light-shielding film is formed on the upper side as described above, the degree of misalignment occurring in the upper and lower plate laminating processes is large, so that a light-shielding film must be formed in consideration of this misalignment. At this time, the margin? A due to misalignment is about 6 to 10 占 퐉. As a result, the aperture ratio is greatly reduced because the light shielding film is formed larger than the width that can actually block the light.

FIG. 2 shows a second example of a conventional liquid crystal display device, in which a light-shielding film is formed on a lower plate.

A light shielding film 23 is formed by evaporating and patterning an opaque conductor on the lower substrate 20 and then an insulating film 25 is deposited on the entire surface and then a signal line 21, And the pixel electrode 22 are formed. The light shielding film 23 is used as a storage electrode and a storage capacitor is formed at a portion where the light shielding film 23 and the pixel electrode 22 overlap.

Since the light shielding film is formed directly on the lower plate, the margin? B due to the misalignment occurring in the adhesion process with the upper plate 24 is about 2 to 3 占 퐉, which is smaller than that in the case of forming the light shielding film on the upper plate shown in Fig. , And the aperture ratio is further improved.

FIG. 3 shows a third example of the conventional liquid crystal display device, which has a much higher aperture ratio than the conventional two liquid crystal display devices described above.

A first insulating film 32 is formed on the scanning line 31L and the signal line 35S and the thin film transistor formed on the lower substrate 30. A pixel electrode 39 is formed on the first insulating film 32, (35D). A light shielding film 37 formed of an opaque conductive material is formed on the edge of the pixel electrode 39 in a superimposed manner. Since the light shielding film 37 occupies a minimum space at the edge portion of the pixel electrode to block light, the aperture ratio is much improved. At this time, the light-shielding film 37 forms a storage capacitor together with the pixel electrode 39 at the edge portion of the pixel electrode 39.

Reference numeral 31G denotes a gate electrode formed so as to protrude from the scanning line, reference numeral 33 denotes an active layer, reference numeral 34 denotes an ohmic contact layer, reference numeral 35S denotes a source electrode formed to protrude from the signal line, reference numeral 36 A second insulating film for insulating the scanning line and the signal line from the light-shielding film as a conductive layer formed on the scanning line and the signal line, and a third insulating film for isolating the light-shielding film 37 from the pixel electrode 39 formed thereon , And (40) represent a protective film.

However, in such a conventional liquid crystal display device, since a light-shielding film formed through an insulating layer is formed on the lower plate to increase the aperture ratio, an insulating film and a conductive layer are further formed, and further, Therefore, there is a problem that productivity and yield are lowered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device capable of increasing the aperture ratio without using an additional mask using a storage electrode formed on the same layer with the same conductive material as a signal line .

1 is a view showing a first example of a conventional liquid crystal display device in which a light shielding film is formed on an upper plate;

2 is a view showing a second example of a conventional liquid crystal display device in which a light-shielding film is formed on a lower plate;

FIG. 3 is a view showing a third example of a conventional liquid crystal display device in which a light-shielding film is formed on a lower plate;

FIG. 4 is a view showing a first embodiment of the liquid crystal display device of the present invention. FIG.

FIGS. 5 and 6 are views showing the manufacturing process of the present invention shown in FIG. 4 as AA 'and BB'

FIG. 7 is a view showing a second embodiment of the liquid crystal display device of the present invention. FIG.

FIGS. 8 and 9 are views showing the manufacturing process of the present invention shown in FIG. 7 as CC 'section and DD' section, respectively.

10 is a view showing a third embodiment of the liquid crystal display device of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

41L: scanning line 41G: gate electrode

42: first insulating film 43S: source electrode

43D: drain electrode 43L: signal line

44: ohmic contact layer 45: active layer

46: second insulating film 49: pixel electrode

41X: Shading layer 43X: Storage electrode

A plurality of thin film transistors formed at intersections of the scanning lines and the signal lines; and a plurality of thin film transistors formed at intersections of the scanning lines and the signal lines, A plurality of storage electrodes formed in the same wiring material as the signal line and located in each of the pixel regions; and a plurality of storage electrodes arranged in the pixel region, And connecting means for connecting to the external common electrode.

According to another aspect of the present invention, there is provided a liquid crystal display device including a plurality of scanning lines and signal lines formed on a substrate so as to intersect with each other to define a plurality of pixel regions in a matrix form and a plurality of thin film transistors formed at intersections of the scanning lines and the signal lines, And forming a plurality of pixel electrodes connected to the drain electrodes, wherein a light shielding layer having a predetermined shape along the signal line with the same conductive material in the same layer of the scanning lines is formed in each pixel region And forming a plurality of storage electrodes on the same layer of the signal line, each of the storage electrodes being located in each of the pixel regions with the same conductive material and connected to the light-shielding layer.

According to another aspect of the present invention, there is provided a liquid crystal display device including a plurality of scanning lines and signal lines formed on a substrate so as to intersect with each other to define a plurality of pixel regions in a matrix form and a plurality of thin film transistors formed at intersections of the scanning lines and the signal lines, A step of forming a light shielding layer having a predetermined shape along the signal line in the same layer of the same conductive material on the scanning line in the pixel region, Forming a plurality of storage electrodes on the same layer of the signal line in the pixel regions with the same conductive material; And forming a transparent wiring.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 4 shows a liquid crystal display device having a bottom gate structure as a first embodiment of the present invention. FIG. 4 (a) shows an array of liquid crystal display devices, FIG. 4 is a cross-sectional view taken along the line AA 'in Fig. 4 (A), and Fig. 4 (C) is a cross-sectional view taken along line BB' of Fig. 4 (A).

A scanning line 41L of a linear shape passes over the insulating substrate 40 and a signal line 43L is formed so as to cross the scanning line 41L. A thin film transistor having a bottom gate structure is formed at the intersection of the scanning line 41L and the signal line 43L and a pixel electrode 49 is connected to the drain electrode 43D of the thin film transistor. A light shielding layer 41X formed of the same conductive material as the scanning line 41L overlaps the signal line 43L in the same layer of the scanning line 41L under the signal line 43L and is positioned in the direction of the signal line 43L.

A storage electrode 43X formed of the same conductive material as that of the signal line 43L is provided for each pixel on the same layer of the signal line 43L above the scanning line 41L as indicated by a dotted line in the drawing. The storage electrode 43X of each pixel is connected to the light-shielding layer 41X and is commonly connected to an external electrode. Accordingly, the storage electrode of the present invention takes a storage on common method. The storage electrode 43X and the light shielding layer 41X are connected to each other through the contact hole formed in the first insulating film 42 as shown in FIG.

Reference numeral 43S denotes a source electrode, reference numeral 41G denotes a gate electrode, reference numeral 44 denotes an ohmic contact layer, reference numeral 45 denotes an active layer, and reference numeral 46 denotes a second insulating film.

In the present embodiment shown in this embodiment, the signal line wiring material and the scanning line wiring material are insulated by the first insulation film 42, and the signal line wiring material and the pixel electrode are insulated by the second insulation film 46. [ As described above, the storage electrode 47 formed of the same wiring material as the signal line overlaps a part of the pixel electrode 47 with the second insulating film 46 interposed therebetween to form a storage capacitor, and the first insulating film 42 And the scanning lines 41L are partially overlapped with each other to form a storage capacitor.

FIGS. 5 and 6 are views showing a manufacturing process of the liquid crystal display device shown in FIG. 4, which is a first embodiment of the present invention, in a sectional view taken along line AA 'and BB' in FIG.

The first conductive layer is deposited on the insulating substrate 40 by a sputtering method and patterned to form the gate electrode 41G and the scanning line 41L, The light-shielding layer 41X is formed. Therefore, the scanning line 41L and the light-shielding layer 41X are formed of the same conductive material in the same layer. Then, a first insulating film 42 is formed on the entire surface of the scanning line 41L and the light-shielding layer 41X. Subsequently, as shown in FIG. 5 (B) and FIG. 6 (B), the amorphous silicon layer and the amorphous silicon layer doped with the amorphous silicon layer are successively deposited on the gate electrode 41G and patterned to form the active layer 45, Layer 44 is formed.

Next, as shown in FIG. 5C and FIG. 6C, a contact hole is formed in a predetermined portion of the first insulating film 42 located above the light-shielding layer 41X, Exposed. The light shielding layer 45 is electrically connected to the storage electrode to be formed later through the contact hole.

Then, as shown in FIGS. 5 (D) and 6 (D), after the second conductive layers are stacked, the signal line 43L, the source electrode 43S and the drain electrode 43D crossing the scanning line are pattern- And a storage electrode 43X having an arbitrary pattern shape are formed. That is, the storage electrode 43X is formed on the same layer with the same wiring material as the signal line 43L. At this time, the signal line 43L is formed so as not to cover the contact hole formed in the first insulating film 42. [ The storage electrode 43X is formed so as to cover the contact hole of the first insulating film 42 and contact the light shielding layer 43X so that the storage electrode 43X of each pixel is connected to the light shielding layer 41X And connected to an external electrode in common. Then, using the source electrode 43S and the drain electrode 43D as a mask, a part of the ohmic contact layer 44 at the lower end thereof is removed.

After the second insulating film 46 is formed on the entire surface, a portion of the upper end of the drain electrode 430 is exposed to the second insulating film 46, as shown in FIG. 5E and FIG. 6H, Thereby forming a contact hole. Thereafter, an ITO layer is deposited on the entire surface, and then patterned to form a pixel electrode 49 connected to the drain electrode 43D.

As shown in the drawing, the pixel electrode 49 overlaps the storage electrode 41X with a part of the second insulating film 46 to form a storage capacitor with the storage electrode 41X. The storage electrode 41X overlaps a part of the scanning line 41L with the first insulating film 42 interposed therebetween to form a storage capacitor.

7 shows a liquid crystal display device having a top gate structure according to a second embodiment of the present invention. Fig. 7 (A) shows a plan view of the liquid crystal display device, Fig. 7 (C) of Fig. 7 (a), and Fig. 7 (c) shows the DD 'section of Fig. 7 (a).

A linear scanning line 73L is passed over the insulating substrate 70 and a signal line 75L is formed so as to cross the scanning line 73L and a thin film transistor is formed at the intersection of the scanning line 73L and the signal line 75L . At this time, the thin film transistor has a top gate structure in which the gate electrode 73G is located at the top, and the source electrode 75S and the drain electrode 75D are connected to the impurity regions 71-1 and 71-2 of the active layer 71, Respectively. A light shielding layer 73X formed of the same conductive material as the scanning line 73L overlaps the signal line 75L and is positioned in the direction of the signal line 75L on the same layer of the scanning line 73L under the signal line 75L.

A storage electrode 75X formed of the same conductive material as that of the signal line 73L is placed in the same layer of the signal line 75L above the scanning line 73L in a predetermined shape as indicated by a dotted line in the drawing. At this time, the storage electrode 75X of each pixel is connected to the light-shielding layer 73X and is commonly connected to an external electrode. Thus, the present invention in this embodiment has a storage electrode that takes a storage on common scheme. The storage electrode 75X and the light shielding layer 73X are connected to each other through a contact hole formed in the second insulating film 74 as shown in (c) of FIG.

In the present invention, as shown in FIG. 7 (B), the signal line wiring material and the scanning line wiring material are insulated by the second insulating film 74, and the signal line wiring material and the pixel electrode are insulated by the third insulating film 76. [ The storage electrode 73X formed with the signal line wiring material overlaps a part of the pixel electrode 79 with the third insulating film 76 interposed therebetween to form a storage capacitor and the second insulating film 74 And is partially overlapped with the scanning line 73L to form a storage capacitor.

Figs. 8 and 9 show the manufacturing process diagrams of the liquid crystal display device shown in Fig. 7, which is the second embodiment of the present invention, in cross section CC 'and DD' section, respectively.

First, amorphous silicon is deposited on the insulating substrate 70, and patterned to form the active layer 71, as shown in FIGS. 8A and 9B. Thereafter, a first insulating film 72 is formed on the entire surface.

Then, as shown in FIG. 8 (B) and FIG. 9 (B), the first conductive layer is laminated on the first insulating film 72 by a sputtering method and then pattern-etched to partially overlap the active layer 71 A gate electrode 73G and a scanning line 73L connected to the gate electrode 73G and a light shielding layer 73X located at a predetermined portion are formed. Thereafter, ions of a high concentration are implanted into the active layer 71 using the gate electrode 73G as a mask to form impurity regions 71-1 and 71-2 on the left and right of the active layer 71, respectively. At this time, the portion of the active layer 71 between the impurity regions 71-1 and 71-2 underlying the gate electrode 73G becomes the channel region 71C.

Next, as shown in FIG. 8 (C) and FIG. 9 (C), a second insulating film is deposited on the entire surface, and then patterned to form a second insulating film 74 and a first insulating film 72, (71-1) and (71-2) and a contact hole for exposing a part of the light-shielding layer 73C.

Thereafter, a second conductive layer is deposited on the entire surface, and then patterned to form source and drain electrodes 75S and 75D and a source electrode 75S, which are connected to the impurity regions 71-1 and 71-2, And a storage electrode 75X having a predetermined shape and connected to the light shielding layer 73X are formed. At this time, the storage electrode 75X is formed so as to overlap with a part of the scanning line 73L and is connected to the light-shielding layer 73X through the contact hole formed in the second insulating film 74. [ The signal line 75L and the storage electrode 75X are formed of the same material in the same layer.

Then, a third insulating film 76 is stacked on the entire surface, and then a part of the upper end of the drain electrode 75D is exposed to the third insulating film 76 (see FIG. Thereby forming a contact hole. Thereafter, an ITO layer is deposited on the entire surface, and then patterned to form a pixel electrode 79 connected to the drain electrode 75D.

In the third embodiment of the present invention, which is described with reference to FIG. 10, unlike the previous two embodiments in which the storage electrode is connected to the light shielding layer, the storage electrode is connected to the transparent wiring formed of the same conductive material as the pixel electrode. At this time, the transparent wiring is formed so as to be insulated from the pixel electrode, and the transparent wiring of each pixel is connected to the external electrodes in contact with the respective storage electrodes.

Since the basic structure of the other parts of the substrate is the same as that described above, only the connection part of the storage electrode and the transparent wiring will be described with reference to the drawings.

10 is a plan view of a portion of the liquid crystal display device according to the present invention in which a storage electrode is connected to a transparent interconnection with a signal line therebetween, and FIG. 10 (B) will be.

A light shielding layer 91X formed of the same material as the scanning line is formed on the insulating substrate 90 along the signal line 93L. At this time, the light-shielding layer 91X and the signal line 93L are formed with the first insulating film 92 interposed therebetween. And is formed through a signal line 92 located above the first insulating film 92. A storage electrode 93X is formed on the same layer as the signal line 93L located above the first insulating layer 92 and is formed of the same material as the signal line 93L and positioned to be separated from the signal line 93L. A transparent wiring 98 formed of the same material as the pixel electrode 99 is connected to the storage electrode 93X through a contact hole formed in the second insulating film 94. [ Therefore, the transparent wiring 98 connects the storage electrodes 93X formed between the pixels.

As described above, in the present invention, after the storage electrode is formed of the same wiring material as the signal line, the storage electrode is connected to the light-shielding layer formed of the same wiring material as the scanning line, or to the transparent wiring formed of the same wiring material as the pixel electrode. That is, the storage electrode, the light shielding layer, and the transparent wiring are formed when forming the signal line, the scanning line, and the pixel electrode, respectively. Therefore, there is no need to use additional deposition processes or masks to form storage electrodes, light shielding layers, and transparent wiring.

Compared with a conventional storage-on-common type liquid crystal display device in which a storage capacitor is connected to a common electrode, the area of the storage electrode covering the pixel electrode is much smaller and the aperture ratio can be sufficiently increased.

Also, as mentioned above, since the storage electrode is commonly connected to the external electrode at the lower portion of the pixel electrode and is held at the one-time voltage, the crosstalk due to the parasitic capacitance between the adjacent scanning line and the signal line can be reduced.

Claims (13)

A plurality of thin film transistors formed at intersections of the scanning lines and the signal lines to define pixel regions in the form of a matrix intersecting with each other on the substrate and a plurality of thin film transistors connected to the drain electrodes of the thin film transistors In a liquid crystal display device having a plurality of pixel electrodes, A plurality of storage electrodes formed in the same wiring material as the signal lines and located in the pixel regions, And connection means for connecting each of the storage electrodes at a portion where the signal line is located and connecting the storage electrode to an external common electrode. The method according to claim 1, Wherein the connecting means is a light shielding layer formed of the same wiring material as the scanning line and positioned in parallel with the signal line along the direction of the signal line. The method according to claim 1, Wherein the connection means is a transparent wiring formed of the same wiring material as the pixel electrode. The method according to claim 1, Wherein the storage electrode is overlapped with a part of the scan line to form a storage capacitor. The method according to claim 1, Wherein the storage electrode overlaps with a part of the pixel electrode to form a storage capacitor. The method according to claim 1, Wherein the thin film transistor has a bottom gate structure. The method according to claim 1, Wherein the thin film transistor has a top gate structure. A plurality of scanning lines and signal lines are formed on the substrate so as to intersect with each other to define a plurality of pixel regions in a matrix form and a plurality of thin film transistors are formed at intersections of the scanning lines and the signal lines, A method of manufacturing a liquid crystal display device comprising a plurality of pixel electrodes, Forming a light-shielding layer having a predetermined shape along the signal line with the same conductive material in the same layer of the scanning line in each pixel region; And forming a plurality of storage electrodes on the same layer of the signal line, each of the storage electrodes being located in each of the pixel regions with the same conductive material and connected to the light-shielding layer. 9. The method of claim 8, Wherein the storage electrode overlaps with a portion of the pixel electrode. 9. The method of claim 8, Wherein the storage electrode overlaps with a portion of the scan line. A plurality of scanning lines and signal lines are formed on the substrate so as to intersect with each other to define a plurality of pixel regions in a matrix form and a plurality of thin film transistors are formed at intersections of the scanning lines and the signal lines, A method of manufacturing a liquid crystal display device comprising a plurality of pixel electrodes, Forming a light-shielding layer having a predetermined shape along the signal line with the same conductive material in the same layer of the scanning line in the pixel region; Forming a plurality of storage electrodes on the same layer of the signal line, each of the storage electrodes being located in each of the pixel regions with the same conductive material; And forming transparent wirings for connecting the storage electrodes in the signal line portion with the same conductive material to the same layer of the pixel electrodes. 12. The method of claim 11, Wherein the storage electrode overlaps with a portion of the pixel electrode. 12. The method of claim 11, Wherein the storage electrode overlaps with a portion of the scan line.