KR101126448B1 - poly silicon liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a polysilicon liquid crystal display device that implements a multi-channel to prevent deterioration of a driving circuit unit.

The polysilicon liquid crystal display according to the present invention is a bar type in which at least one unit channel polycrystalline silicon layer is connected and exposed in a driving circuit of a polysilicon liquid crystal display including a multichannel thin film transistor including a plurality of unit channels. (bar type) It is characterized in that a semiconductor layer contact hole including a contact hole is formed.

Accordingly, an object of the present invention is to provide a polysilicon liquid crystal display which prevents a defect due to deterioration generated in a channel portion in a driving circuit portion of a polysilicon liquid crystal display.

Multi channel, unit channel, deterioration, bar type

Description

Poly silicon liquid crystal display device

1 is a schematic diagram of a general driving circuit unit integrated liquid crystal display device;

2 is a plan view illustrating a multi-channel unit of a thin film transistor of a driving circuit unit of a conventional polysilicon liquid crystal display.

3 is a cross-sectional view taken along the line A-A 'in FIG.

4A and 4B are plan view photographs and cross-sectional views showing channel part defects due to deterioration in a driving circuit part of a conventional polysilicon liquid crystal display.

FIG. 5 is a plan view showing a portion of a driving circuit of a polysilicon liquid crystal display as a first embodiment according to the present invention; FIG.

6 is a cross-sectional view taken along the line B-B 'in FIG.

7 is a cross-sectional view illustrating a p-type and n-type thin film transistor of a driving circuit unit of a polysilicon liquid crystal display according to the present invention.

8 is a plan view showing a channel portion of a driving circuit portion of a polysilicon liquid crystal display device according to a second embodiment according to the present invention;

9 is a plan view showing a channel portion of a driving circuit portion of a polysilicon liquid crystal display as a third embodiment according to the present invention;

Description of the Related Art [0002]                 

320, 420, 520, 620: substrate 325, 425, 525, 625: buffer layer

330, 530, 630: semiconductor layer 330s, 530s, 630s: source region

330d, 530d, 630d: drain region 330a, 530a, 630a,: channel region

345, 445, 545, 645: gate insulating film 350, 550, 650: gate electrode

370, 470, 570, 670: interlayer insulation film

373a, 573a, 673a: source semiconductor layer contact hole

373b, 573b, 673b: drain semiconductor layer contact hole

380a, 580a, 680a: source electrode 380b, 580b, 680b: drain electrode

435: n-type semiconductor layer 440: p-type semiconductor layer

455, 460: gate electrode

475a, 475b, 477a, 477b: semiconductor layer contact hole

483a, 487a: source electrode 483b, 487b: drain electrode

490: protective layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a polysilicon liquid crystal display device that implements a multi-channel to prevent deterioration of a driving circuit unit.

Recently, a liquid crystal display device has been spotlighted as a next generation advanced display device having low power consumption, good portability, technology intensiveness, and high added value.                         

The liquid crystal display device injects a liquid crystal between an array substrate including a thin film transistor (TFT) and a color filter substrate, and uses a non-light emitting device that obtains an image effect by using a difference in refractive index of light due to the anisotropy of the liquid crystal. Means an image display device.

Currently, an active matrix liquid crystal display device (AM-LCD) in which the thin film transistor and the pixel electrode are arranged in a matrix manner has been attracting the most attention due to its excellent resolution and ability to implement video. Hydrogenated amorphous silicon (a-Si: H) is mainly used as a device because low-temperature processing is possible and low-cost insulating substrates can be used.

However, because hydrogenated amorphous silicon has disordered atomic arrangements, weak Si-Si bonds and dangling bonds exist, which are converted into a quasi-stable state when irradiated with light or applied with an electric field, and used as a thin film transistor device. Stability is emerging as a problem, and its electrical characteristics (low field effect mobility: 0.1 ~ 1.0 ㎠ / V? S) are poor, making it difficult to use as a driving circuit.

Therefore, in general, a driving device manufactured separately is connected to a liquid crystal panel, and as a representative example, a driving device is manufactured in a tape carrier package (TCP) and attached to a liquid crystal panel.

Accordingly, in the TCP, a plurality of circuits are attached between the printed circuit board (PCB) substrate and the liquid crystal panel to receive a signal input from the PCB substrate and transmit the signal to the liquid crystal panel.                         

However, such a configuration occupies a large part of the cost of the practical use of the driving IC, and as the resolution of the liquid crystal panel increases, the pad pitch outside the substrate connecting the gate wiring and the data wiring of the thin film transistor substrate with the TCP is increased. The shortening makes TCP bonding itself difficult.

On the other hand, since polysilicon has a greater field effect mobility than amorphous silicon, a driving circuit can be made on a substrate. By using the polysilicon to make a driving circuit directly on a substrate, the cost of the driving IC can be reduced and the mounting is simplified. .

In particular, the polysilicon liquid crystal display implements a multi-channel in which a unit channel is connected in parallel in a wide width transistor having a wide channel width in a driving circuit unit.

1 is a schematic view of a general driving circuit unit integrated liquid crystal display device.

As shown, the driving circuit portion 105 and the display portion 103 are formed together on the insulating substrate 101.

The display unit 103 is positioned at the center of the substrate 101, and gate and data driving circuit units 105a and 105b are positioned at one side of the display unit 103 and the other side not parallel thereto.

The display unit 103 includes a plurality of gate wires 107 connected to the gate driving circuit unit 105a and a plurality of data wires 109 connected to the data driving circuit unit 105b intersect with each other. The pixel electrode 110 is formed in the defined pixel region P, and the thin film transistor T connected to the pixel electrode 110 is positioned at the intersection of the two wires.

In addition, the gate and data driving circuit unit are connected to an external signal input terminal 112.

The gate and data driver circuits 105a and 105b internally adjust an external signal input through the external signal input terminal 112 to display the display control signal to the display unit 103 through the gate and data wires 107 and 109, respectively. And an apparatus for supplying a data signal.

Accordingly, the gate and data driver circuits 105a and 105b are formed with a complementary metal-oxide semiconductor (CMOS) structure thin film transistor (not shown), which is an inverter, to properly output an input signal. It is.

2 is a plan view illustrating a multi-channel portion of a thin film transistor of a driving circuit unit of a conventional polysilicon liquid crystal display, and FIG. 3 is a cross-sectional view taken along line AA ′ of FIG. 2.

As shown in FIG. 2 and FIG. 3, the thin film transistor of the driving circuit of the conventional polysilicon liquid crystal display constitutes a multi-channel composed of four unit channels C1, C2, C3, and C4, and the insulating substrate 220. The buffer layer 225 is formed on the semiconductor layer 230, and the semiconductor layer 230 is formed on the buffer layer 225.

The semiconductor layer 230 is formed such that four unit channels C1, C2, C3, and C4 are formed, and the source region 230s and the drain region at one end of the unit channels C1, C2, C3, and C4. The unit channels are connected in parallel to form 230d.

A channel region 230a is formed between the source region 230s and the drain region 230d.

A gate insulating film 245 is formed on the semiconductor layer 230, and a gate electrode 250 is formed on the gate insulating film 245 over the unit channels C1, C2, C3, and C4. .

An interlayer insulating layer 270 is formed on the gate electrode 250, and semiconductor layer contact holes 273a and 273b penetrating the interlayer insulating layer 270 and the gate insulating layer 245 are formed.

The source electrode 280a and the drain electrode 280b are formed on the source region 230s and the drain region 230d.

The source electrode 280a and the drain electrode 280b are formed in the gate insulating layer 245 and the interlayer insulating layer 270 to expose the source region 230s and the drain region 230d of the semiconductor layer 230. The semiconductor layer 230 is connected through a plurality of source and drain semiconductor layer contact holes 273a and 273b.

At least one source and drain semiconductor layer contact hole 273a and 273b is formed at both ends of each of the unit channels C1, C2, C3, and C4.

Since the driving circuit unit is configured to apply a driving signal when the liquid crystal display device is operated, a large amount of current flows during driving, and thus self heating occurs in the channel unit.                         

As a result of such deterioration, a current surge occurs between the source electrode and the drain electrode in the channel part, and a short occurs, thereby causing a breakdown.

4A and 4B are plan view photographs and cross-sectional views illustrating channel defects due to deterioration in a driving circuit unit of a conventional polysilicon liquid crystal display.

As shown in FIGS. 4A and 4B, the metal forming the source electrode 280a and the drain electrode 280b melts and moves toward the channel due to self heating of the channel portion in the driving circuit of the polysilicon liquid crystal display. As a result, a short occurs.

That is, since the driving circuit portion must apply a driving signal, a large current flows during the driving. As a result, deterioration (self heating) occurs in the channel part, and a short circuit occurs due to a current surge between the source electrode 280a and the drain electrode 280b in the channel part. Problems will arise.

In detail, the driving circuit unit generates a breakdown due to a short between the source and drain electrodes 280a and 280b under a high power (Vds × Ids) condition.

In particular, a short occurs in the channel portion at the position where the semiconductor layer contact holes 273a and 273b are formed. This is because the contact area between the source and drain electrodes 280a and 280b and the semiconductor layer 230 has a small current. It appears to be concentrated.

 According to the present invention, a channel portion is formed by connecting a source and a drain contact hole formed in at least one unit channel to form a bar type contact hole when a thin film transistor having a multi channel is formed in a driving circuit of a polysilicon liquid crystal display. Disclosure of Invention An object of the present invention is to provide a polysilicon liquid crystal display device which prevents a defect due to deterioration generated in the device.

In order to achieve the above object, the polysilicon liquid crystal display device according to the present invention includes a multi-channel thin film transistor including a plurality of unit channels.

A polycrystalline silicon layer forming the unit channel on a substrate; A gate insulating film formed over the polycrystalline silicon layer; A gate electrode formed on the gate insulating film corresponding to a portion of the polycrystalline silicon layer; An interlayer insulating film formed on the gate electrode; A semiconductor layer contact hole penetrating through the gate insulating film and the interlayer insulating film, and including a bar type contact hole for connecting and exposing at least one unit channel polycrystalline silicon layer at both sides of the gate electrode; And a source and a drain electrode contacting the polycrystalline silicon layer through the semiconductor layer contact hole.

N + or p + impurity ions are doped on the surface of the polycrystalline silicon layer in contact with the source and drain electrodes.

The bar type contact hole may be formed in a unit channel in which driving current is concentrated.

In the multi-channel thin film transistor, at least two bar type contact holes are formed at one side of the channel.

Hereinafter, a polysilicon liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a plan view showing a portion of a driving circuit of a polysilicon liquid crystal display as a first embodiment according to the present invention, and FIG. 6 is a cross-sectional view taken along line BB ′ in FIG. 5.

As shown in FIG. 5 and FIG. 6, the driving circuit of the polysilicon liquid crystal display according to the present invention constitutes a multi-channel composed of four unit channels C1 ', C2', C3 ', and C4'. Doing.

In the multi-channel, the semiconductor layer 330 forms four unit channels C1 ', C2', C3 'and C4', and the unit channels C1 ', C2', C3 'and C4'. The semiconductor layer 330 of the unit channel is connected to form a source region 330s and a drain region 330d at both ends thereof.

A channel region 330a is formed between the source region 330s and the drain region 330d.

A gate insulating layer 345 is formed on the semiconductor layer 330, and the gate electrode 350 is disposed on the gate insulating layer 345 over the unit channels C1 ′, C2 ′, C3 ′, and C4 ′. Is formed.                     

An interlayer insulating layer 370 is formed on the gate electrode 350, and semiconductor layer contact holes 373a and 373b penetrating the interlayer insulating layer 370 and the gate insulating layer 345 are formed.

A source electrode 380a and a drain electrode 380b are formed on the source region 330s and the drain region 330d.

The source electrode 380a and the drain electrode 380b may include source and drain contact holes formed in the gate insulating layer 345 to expose the source region 330s and the drain region 330d of the semiconductor layer 330. The semiconductor layer 330 is connected through 373a and 373b.

In this case, the source and drain semiconductor layer contact holes 373a and 373b may have bar types at source and drain regions 330s and 330d at both ends of the unit channels C1 ', C2', C3 'and C4'. And the source and drain regions 330s and 330d of the semiconductor layer 330 to which the four unit channels C1 ', C2', C3 'and C4' are connected.

That is, when the unit channels constituting the multi-channel are referred to as first to fourth unit channels, respectively, to transmit a signal from the source electrode 380a to the drain electrode 380b through the first to fourth unit channels. Source and drain semiconductor layer contact holes 373a and 373b exposing source and drain regions 330s and 330d of the semiconductor layer 330 are formed, and source and drain electrodes 380a and 380b and the semiconductor layer 330 are formed. The source and drain semiconductor layer contact holes 373a and 373b may contact the source and drain regions 330s and 330d of the first to fourth unit channels C1 ', C2', C3 'and C4'. Expose                     

The driving circuit unit configured as described above has an effect of preventing current from flowing concentrated in a portion of the channel portion when driving the liquid crystal display device, thereby preventing self heating of the channel portion.

7 is a cross-sectional view illustrating a p-type and n-type thin film transistor of a driving circuit unit of a polysilicon liquid crystal display according to the present invention.

Referring to FIG. 7, the n-type semiconductor layer 435 and the p-type semiconductor layer 440 are formed to be spaced apart from each other by a predetermined interval on the transparent insulating substrate 420 on which the buffer layer 425 is formed. The gate insulating layer 445 is formed on the entire surface of the type and p-type semiconductor layers 435 and 440, and the gate electrodes 455 and 460 are formed on the gate insulating layer 445.

An interlayer insulating layer 470 including semiconductor layer contact holes 475a, 475b, 477a, and 477b is formed on the gate electrode 455 and 460 over the entire surface of the substrate 420. Source and drain electrodes (483a, 487a, 483b, 487b) contacting the n-type and p-type semiconductor layers 435, 440 through the semiconductor layer contact holes 475a, 475b, 477a, and 477b, respectively. Is formed, and a protective layer 490 is formed over the entire surface of the source and drain electrodes 448a and 487a and 483b and 487b.

A region of the n-type semiconductor 435 corresponding to the gate electrode 455 and formed under the gate insulating layer 445 forms an active layer 435a and is in contact with the source and drain electrodes 483a and 483b. The semiconductor layer including n forms an n + doped n-type ohmic contact layer 435c, and an n-doped LDD layer 435b is formed between the active layer 435a and the n-type ohmic contact layer 435c.

In addition, since the p-type semiconductor layer 440 uses holes as carriers, the deterioration and leakage current of the carriers are less affected than the n-type thin film transistors. Thus, the p-type semiconductor layer 440 corresponds to the gate electrode 460 without forming an LDD layer. A semiconductor layer region under the gate insulating layer 445 forms an active layer 440a, and an outer region of the active layer 440a forms a p-type ohmic contact layer 440c.

8 is a plan view showing a channel portion of a driving circuit portion of a polysilicon liquid crystal display according to a second embodiment of the present invention, and FIG. 9 is a plan view showing a channel portion of a driving circuit portion of a polysilicon liquid crystal display. It is a top view which shows a channel part.

8 and 9, the driving circuit of the polysilicon liquid crystal display includes a multi-channel thin film transistor including a plurality of unit channels C1 ′, C2 ′, C3 ′, and C4 ′, each of which includes a multi-channel thin film transistor. The semiconductor layer contact hole ((1) for connecting the source electrodes 580a and 680a and the drain electrodes 580b and 680b with the semiconductor layers 530 and 630 with respect to the unit channels C1 ', C2', C3 'and C4'. 573a, 673a) and 573b, 673b) are formed.

In this case, the semiconductor layer contact holes 573a, 673a, and 573b and 673b may include one bar type contact hole by connecting contact holes of at least one unit channel.

In FIG. 8, the bar-type semiconductor layer contact holes 573a and 573b are formed in the unit channel where the driving current is concentrated, and thus, the channel deterioration can be prevented due to the concentration of current.                     

In FIG. 9, the bar type contact hole connects the semiconductor layer contact holes 673a and 673b of the neighboring unit channel to form a plurality of bar type contact holes, thereby effectively preventing channel degradation.

Here, the reference numerals which are not described are the same as the above-described embodiments, and thus detailed descriptions thereof will be omitted.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

The driving circuit of the polysilicon liquid crystal display according to the present invention has an effect of preventing deterioration of the channel portion by forming a bar type contact hole of at least one unit channel in a thin film transistor having a multi-channel. have.

In addition, the present invention has an effect of improving the reliability since no defect occurs in the driving circuit unit even when the device is driven for a long time in the polysilicon liquid crystal display.

Claims (7)

In the driving circuit portion of the polysilicon liquid crystal display device including a multi-channel thin film transistor consisting of a plurality of unit channels, A polycrystalline silicon layer forming a plurality of source and drain regions respectively positioned on the plurality of unit channels and on both sides of the plurality of unit channels; A gate insulating film formed over the polycrystalline silicon layer; A gate electrode formed on the gate insulating layer corresponding to a partial region of the polycrystalline silicon layer; An interlayer insulating film formed on the gate electrode; A bar type source contact hole penetrating through the gate insulating film and the interlayer insulating film to expose a plurality of source regions corresponding to the plurality of unit channels; A bar type drain contact hole penetrating the gate insulating film and the interlayer insulating film to expose a plurality of drain regions corresponding to the plurality of unit channels; A source electrode contacting the plurality of source regions exposed together through the source contact hole; A drain electrode contacting the plurality of drain regions exposed together through the drain contact hole; Including, The plurality of source regions are connected to each other, The plurality of drain regions are connected to each other driving circuit portion of the polysilicon liquid crystal display device. The method of claim 1, And n + or p + impurity ions doped on the surfaces of the source and drain regions. The method of claim 1, And the bar type source contact hole or the bar type drain contact hole are formed in a unit channel in which driving current is concentrated. The method of claim 1, And a plurality of bar type source contact holes or bar type drain contact holes formed at one side of the channel in the multi-channel thin film transistor. delete delete delete

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