KR19980025515A - LCD and its manufacturing method - Google Patents

Abstract

The present invention relates to a liquid crystal display device and a method for manufacturing the same, which can increase the aperture ratio without using an additional mask by using a storage electrode formed on the same layer as the signal line and the same conductive material. A liquid crystal including a plurality of scan lines and signal lines crossing each other to define a pixel region having a matrix form, a plurality of thin film transistors formed at an intersection of the scan lines and the signal lines, and a plurality of pixel electrodes connected to drain electrodes of the thin film transistors A display device comprising: a plurality of storage electrodes formed of the same wiring material as the signal line and positioned in each of the pixel regions, and connecting means for connecting each of the storage electrodes at a portion where the signal line is positioned to connect to an external common electrode; It is made to include.

Description

LCD and its manufacturing method

1 is a diagram 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.

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.

4 shows a first embodiment of a liquid crystal display of the present invention.

5 and 6 are cross-sectional views of the manufacturing process of the present invention shown in FIG.

7 shows a second embodiment of a liquid crystal display of the present invention.

8 and 9 are cross-sectional views taken along line CC 'and DD', respectively, of the manufacturing process of the present invention shown in FIG.

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

* Description of the symbols for the main parts of the drawings *

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: Light shield layer 43X: Storage electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly, to a liquid crystal display device having a structure for improving an aperture ratio and a method for manufacturing the same.

A general liquid crystal display device has a thin film transistor array substrate (hereinafter referred to as a lower plate) and a color filter substrate (hereinafter referred to as an upper plate), and has a structure in which a liquid crystal is filled between two substrates. In the lower plate, a thin film transistor, which is a switching element, and a pixel (PIXEL: Picture Element) based on the pixel electrode connected to the drain electrode of the thin film transistor are arranged vertically and horizontally, and the gate electrodes of each thin film transistor are connected to each other along one direction. A plurality of signal lines are formed to connect the plurality of scan lines and the source electrodes of the thin film transistors along one direction. On the upper plate, color filters are formed so as to have one dye of RGB (red-green-blue) corresponding to each pixel.

In the liquid crystal display having such a structure, there is a part that cannot completely control the light transmitted from the backlight due to the structure of the signal line, the scan line, the thin film transistor, and the pixel electrode provided on the lower plate. Thus, as shown in FIG. 1, an area corresponding to each of the color filters (not shown) of the upper plate 14, that is, the upper portion of the signal line 11, the scanning line, and the thin film transistor region of the lower plate 10. A black matrix 13 formed of chromium is formed on the substrate. A protective film is formed on the surface of the color filter and the light shielding film, and a common electrode is formed on the upper surface of the color filter and the light blocking film to apply an electric field to the liquid crystal.

However, the conventional liquid crystal display device having the light shielding film formed thereon has a large degree of misalignment generated in the upper and lower panel bonding processes, and thus, the light shielding film should be formed in consideration of this. At this time, the margin Δa due to misalignment is about 6 to 10 μm. As a result, the aperture ratio was greatly reduced because the light shielding film was formed larger than the width capable of actually blocking light.

FIG. 2 shows a second example of a conventional liquid crystal display, showing a case where a light shielding film is formed on a lower plate.

After depositing and patterning an opaque conductor on the lower plate 20 to form a light shielding film 23, the insulating film 25 is deposited on the entire surface, and then the signal line 21, the scanning line, and the thin film transistor are formed on the insulating film 25. And the pixel electrode 22 are formed. The light shielding film 23 is used as the storage electrode, and the storage capacitor is formed at a portion where the light shielding film 23 and the pixel electrode 22 overlap each other.

Since the light shielding film is directly formed on the lower plate, the margin Δb due to misalignment occurring in the bonding process with the upper plate 24 is about 2 to 3 µm, which is smaller than that of forming the light shielding film on the upper plate shown in FIG. The aperture ratio is further improved.

FIG. 3 shows a third example of the conventional liquid crystal display device, and has a structure in which the aperture ratio is further improved than the two conventional liquid crystal display devices described.

The first insulating film 32 is formed on the scanning line 31L, the signal line 35S, and the thin film transistor formed on the lower plate 30, and the pixel electrode 39 is formed on the first insulating film 32 to drain the thin film transistor. Connected to 35D. A light shielding film 37 formed of an opaque conductor overlaps the edge portion of the pixel electrode 39. As such, since the light blocking film 37 occupies a minimum space at the edge of the pixel electrode to block light, the aperture ratio is much improved. In this case, the light blocking 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 to protrude from the scan line, 33 an active layer, 34 an ohmic contact layer, and 35S a source electrode formed to protrude from the signal line. Is a second insulating film which insulates the scan line and the signal line from the conductive parent light shielding film formed thereon, and 38 is a third insulating film which insulates the light shielding film 37 from the pixel electrode 39 formed thereon. , 40 denotes a protective film.

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

The present invention has been made to solve the above problems, and to provide a liquid crystal display device that can increase the aperture ratio without using an additional mask by using a storage electrode formed on the same layer with the same conductive material as the signal line. .

To this end, the present invention provides a substrate, a plurality of scan lines and signal lines that cross each other to define a pixel region in a matrix form, a plurality of thin film transistors formed at an intersection of the scan lines and the signal lines, and a plurality of thin film transistors. A liquid crystal display device having a plurality of pixel electrodes connected to a drain electrode, the liquid crystal display device comprising: a plurality of storage electrodes formed of the same wiring material as the signal line and positioned in each of the pixel regions, and each of the storage electrodes in a portion where the signal line is located. It comprises a connecting means for connecting to the external common electrode by connecting the.

The present invention also defines a plurality of pixel regions in a matrix form by forming a plurality of scan lines and signal lines to cross each other on a substrate, and forms a plurality of thin film transistors at the intersections of the scan lines and the signal lines. A method of manufacturing a liquid crystal display device for forming a plurality of pixel electrodes connected to a drain electrode, the method comprising: forming a light blocking layer having a predetermined shape in the pixel region along the signal line with the same conductive material on the same layer of the scan line, respectively; And forming a plurality of storage electrodes on the same layer of the signal line, each of the pixel regions being made of the same conductive material and connected to the light blocking layer.

The present invention also defines a plurality of pixel regions in a matrix form by forming a plurality of scan lines and signal lines to cross each other on a substrate, and forms a plurality of thin film transistors at the intersections of the scan lines and the signal lines. A method of manufacturing a liquid crystal display device for forming a plurality of pixel electrodes connected to a drain electrode, the method comprising: forming light blocking layers each having a predetermined shape along the signal line with the same conductive material on the same layer of the scan line. And forming a plurality of storage electrodes positioned in each of the pixel regions on the same layer of the signal line with the same conductive material, and connecting the storage electrodes on the signal line portion with the same conductive material on the same layer of the pixel electrode. It includes a step of 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 thin film transistor having a bottom gate structure according to the first embodiment of the present invention. FIG. 4 (a) shows an array of liquid crystal display devices, and FIG. Section AA 'of FIG. 4A is a cross-sectional view, and FIG. 4C is a cross-section BB' of FIG. 4A.

A scanning line 41L in a straight line passes on the insulating substrate 40 and crosses the scanning line 41L to form a signal line 43L. A thin film transistor having a bottom gate structure is formed at the intersection of the scan line 41L and the signal line 43L, and the pixel electrode 49 is connected to the drain electrode 43D of the thin film transistor. In the same layer of the scanning line 41L below the signal line 43L, a light shielding layer 41X formed of the same conductive material as the scanning line 41L is positioned in the signal line 43L direction overlapping the signal line 43L.

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

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

In the present invention shown in this embodiment, the signal line wiring member and the scan line wiring member are insulated by the first insulating film 42, and the signal line wiring material and the pixel electrode are insulated by the second insulating film 46. Therefore, as mentioned, 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 therebetween to form a storage capacitor, and the first insulating film 42. ) And a portion overlap with the scanning line 41L to form a storage capacitor.

5 and 6 show manufacturing process diagrams of the liquid crystal display shown in FIG. 4, which is the first embodiment of the present invention, in the AA 'cross section and the BB' cross section, respectively.

As shown in FIGS. 5A and 6A, the first conductive layer is laminated on the insulating substrate 40 by a sputtering method, followed by pattern etching to form the gate electrode 41G and the scan line 41L. The light shielding layer 41X is formed. Therefore, the scan line 41L and the light shielding layer 41X are formed of the same conductive material on the same layer. Subsequently, a first insulating film 42 is formed over the scanning line 41L and the light blocking layer 41X.

Subsequently, as shown in FIGS. 5B and 6B, an amorphous silicon layer and a doped amorphous silicon layer are successively stacked on the gate electrode 41G, and then pattern-etched to form an active layer 45 and an ohmic contact. Form layer 44.

Next, as shown in FIGS. 5C and 6C, a contact hole is formed in a predetermined portion of the first insulating film 42 positioned on the light shielding layer 41X, and the predetermined light shielding layer 41X is formed. Expose the part. Through the contact hole, the light blocking layer 45 is then electrically connected to the storage electrode to be formed.

Subsequently, as shown in FIG. 5D and FIG. 6D, the second conductive layer is laminated, and then pattern-etched to cross the scan line 43L, source electrode 43S, and drain electrode 43D. And a storage electrode 43X having an arbitrary pattern shape. That is, the storage electrode 43X is formed on the same layer with the same wiring material as the signal line 43L. In this case, the signal line 43L is formed so as not to cover the contact hole formed in the first insulating layer 42. The storage electrode 43X is formed so as to contact the light blocking layer 43X by covering the contact hole of the first insulating layer 42 so that the storage electrode 43X of each pixel is connected to the light blocking layer 41X positioned over the adjacent pixel. It is connected to the external electrode in common. Thereafter, a portion of the ohmic contact layer 44 at the bottom thereof is removed using the source electrode 43S and the drain electrode 43D as a mask.

Next, as shown in FIG. 5 (e) and FIG. 6 (e), the second insulating film 46 is formed on the entire surface, and then a part of the upper end of the drain electrode 43D is exposed on the second insulating film 46. Then, as shown in FIG. A contact hole is formed. Subsequently, the ITO layer is stacked on the entire surface, and then pattern-etched to form the pixel electrode 49 connected to the drain electrode 43D.

As shown in the figure, the pixel electrode 49 overlaps a portion of the pixel electrode 49 with the storage electrode 41X and the second insulating layer 46 interposed therebetween to form the storage electrode 41X and the storage capacitor. The storage electrode 41X overlaps a portion of the scan line 41L with the first insulating layer 42 therebetween to form a storage capacitor.

FIG. 7 illustrates a liquid crystal display device having a top gate structure according to a second embodiment of the present invention. FIG. 7A is a plan view of the LCD device, and FIG. 7B is 7B. Section (a) of Fig. 7 (a) shows Section DD 'of Fig. 7 (a).

A scan line 73L in a straight line passes on the insulating substrate 70, and a signal line 75L is formed to cross the scan line 73L, and a thin film transistor is formed at an intersection of the scan line 73L and the signal line 75L. It is. In this case, the thin film transistor has a top gate structure in which the gate electrode 73G is positioned above, and the source electrode 75S and the drain electrode 75D are impurity regions 71-1 and 71-2 of the active layer 71. Is connected. In the same layer of the scan line 73L below the signal line 75L, the light shielding layer 73X formed of the same conductive material as the scan line 73L overlaps the signal line 75L so that the signal line 75L is positioned in the direction.

A storage electrode 75X formed of the same conductive material as the signal line 73L is positioned in a predetermined shape on the same layer of the signal line 75L above the scan line 73L, as indicated by a dotted line in the figure. In this case, the storage electrode 75X of each pixel is connected to the light blocking layer 73X and is commonly connected to an external electrode. Therefore, the present invention in this embodiment has a storage electrode that takes a storage on common method. The storage electrode 75X and the light shielding layer 73X are connected through a contact hole formed in the second insulating film 74, as shown in FIG.

In the present invention, as shown in FIG. 7B, the signal line wiring member and the scan line wiring member 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. As shown in FIG. Therefore, as mentioned, 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 therebetween to form a storage capacitor, and the second insulating film 74 is formed. A portion overlaps with the scan line 73L to form a storage capacitor.

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

First, as shown in FIGS. 8A and 9B, amorphous silicon is laminated on the insulating substrate 70, and then pattern-etched to form the active layer 71. FIG. Thereafter, the first insulating layer 72 is laminated on the entire surface.

Subsequently, as shown in FIGS. 8B and 9B, the first conductive layer is laminated on the first insulating film 72 by the sputtering method, and then pattern-etched to partially overlap the active layer 71. A gate electrode 73G, a scan line 73L connected to the gate electrode 73G, and a light shielding layer 73X positioned at a predetermined portion are formed. Thereafter, a high concentration of ions 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 sides of the active layer 71, respectively. In this case, a portion of the active layer 71 between the impurity regions 71-1 and 71-2 disposed below the gate electrode 73G becomes the channel region 71C.

Next, as shown in FIGS. 8C and 9C, a second insulating film is laminated on the entire surface, and then pattern-etched to form impurity regions of the active layer in the second insulating film 74 and the first insulating film 72. Contact holes for exposing (71-1) and (71-2) and contact holes for exposing a part of the light shielding layer 73C are formed.

Subsequently, the second conductive layer is stacked on the entire surface, and then pattern-etched on the source electrode 75S, the drain electrode 75D, and the source electrode 75S respectively connected to the impurity regions 71-1, 71-2. A signal line 75L to be connected and a storage electrode 75X having a predetermined shape and connected to the light blocking layer 73X are formed. In this case, the storage electrode 75X is formed to overlap a portion of the scan line 73L, and is formed to be connected to the light blocking layer 73X through a contact hole formed in the second insulating layer 74. The signal line 75L and the storage electrode 75X are formed of the same material on the same layer.

Next, as shown in FIGS. 8D and 9D, after stacking the third insulating film 76 on the entire surface, the upper portion of the drain electrode 75D is exposed to the third insulating film 76. A contact hole is formed. Subsequently, the ITO layer is stacked on the entire surface, and then pattern-etched to form the pixel electrode 79 connected to the drain electrode 75D.

Unlike the previous two embodiments in which the storage electrode is connected to the light blocking layer, in the third embodiment of the present invention described with reference to FIG. 10, the storage electrode is connected to the transparent wiring formed of the same conductive material as the pixel electrode. In this case, the transparent wiring is formed to be insulated from the pixel electrode, and the transparent wiring of each pixel is in contact with each storage electrode and is commonly connected to an external electrode.

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

FIG. 10A is a plan view of a portion of the liquid crystal display of the present invention in which a storage electrode is connected to a transparent wiring centered on a signal line, and FIG. 10B is a cross-sectional view of EE 'of FIG. 10A. will be.

A light blocking layer 91X formed of the same material as the scan line is formed on the insulating substrate 90 along the signal line 93L. In this case, the light blocking layer 91X and the signal line 93L are formed through the first insulating film 92. It is formed through the signal line 92 positioned above the first insulating film 92. A storage electrode 93X is formed on the signal line 93L positioned above the first insulating layer 92, and formed of the same material as the signal line 93L and positioned to be separated from the signal line 93L. The 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 layer 94. Therefore, the transparent wiring 98 connects the storage electrodes 93X formed between the pixels, respectively.

As described above, in the present invention, the storage electrode is formed of the same wiring material as the signal line, and then connected to the light shielding layer formed of the same wiring material as the scan 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 respectively formed when the signal line, the scan line, and the pixel electrode are formed. This eliminates the need for additional deposition processes or masks to form storage electrodes, light shielding layers, and transparent wiring. The area of the storage electrode covering the pixel electrode is much smaller than that of the conventional storage on common type liquid crystal display device which connects the storage capacitor to the common electrode, thereby sufficiently increasing the aperture ratio. In addition, as mentioned, since the storage electrode is commonly connected to the external electrode under the pixel electrode and maintained at a constant voltage, cross talk due to parasitic capacitance with neighboring scan lines or signal lines can be reduced.

Claims (13)

A plurality of scan lines and signal lines defining a substrate, a plurality of scan lines and signal lines crossing each other to define a pixel region in a matrix form, a plurality of thin film transistors formed at an intersection of the scan lines and the signal lines, and a drain electrode of the thin film transistors. In a liquid crystal display device having a plurality of pixel electrodes, A plurality of storage electrodes formed of the same wiring material as the signal lines and positioned in each of the pixel regions; And connecting means for connecting each of the storage electrodes to an external common electrode at a portion where the signal line is located. The method of claim 1, And the connection means is formed of the same wiring material as the scan line, and is a light blocking layer positioned parallel to the signal line along the direction of the signal line. The method of claim 1, And the connecting means is a transparent wiring formed of the same wiring material as the pixel electrode. The method of claim 1, And the storage electrode overlaps a portion of the scan line to form a storage capacitor. The method of claim 1, And the story electrode is centrally disposed with a portion of the pixel electrode to form a storage capacitor. The method of claim 1, The thin film transistor has a bottom gate structure. The method of claim 1, The thin film transistor has a top gate structure. A plurality of pixel regions in a matrix form are formed by crossing a plurality of scan lines and signal lines on a substrate, and a plurality of thin film transistors are formed at the intersections of the scan lines and the signal lines, and connected to drain electrodes of the thin film transistors. In the method of manufacturing a liquid crystal display device forming a plurality of pixel electrodes, Forming a light shielding layer having a predetermined shape in each pixel region along the signal line with the same conductive material on the same layer of the scan line; And forming a plurality of storage electrodes on the same layer of the signal line, each of the pixel regions being made of the same conductive material and connected to the light blocking layer. The method of claim 8, And the storage electrode is formed to overlap a portion of the pixel electrode. The method of claim 8, And the storage electrode is formed to overlap a portion of the scan line. A plurality of pixel regions in a matrix form are formed by crossing a plurality of scan lines and signal lines on a substrate, and a plurality of thin film transistors are formed at the intersections of the scan lines and the signal lines, and connected to drain electrodes of the thin film transistors. In the method of manufacturing a liquid crystal display device forming a plurality of pixel electrodes, Forming a light shielding layer having a predetermined shape in the pixel area along the signal line with the same conductive material on the same layer of the scanning line, Forming a plurality of storage electrodes on the same layer of the signal line, each of the pixel regions being made of the same conductive material; And forming a transparent wiring on the same layer of the pixel electrode with the same conductive material to connect the storage electrode at the signal line portion. The method of claim 11, And the storage electrode is formed to overlap a portion of the pixel electrode. The method of claim 11, And the storage electrode is formed to overlap a portion of the scan line.