KR20010058179A - Tft-lcd with tft of asymmetry source/drain structure - Google Patents

Abstract

PURPOSE: A thin film transistor liquid crystal display device having an asymmetric source/drain structure is to form carrier mobility and an electric field uniformly and prevent a degradation of a channel layer. CONSTITUTION: A gate line(2) and a data line(8) are crossed through a gate insulating layer. A pixel electrode(4) is formed within a predetermined pixel area defined by the gate line and the data line. A thin film transistor(10) includes a gate electrode(2a), a channel layer(3), the first and the second source electrodes(5a,5b) and a drain electrode(6). The gate electrode is extended from the gate line inwardly. The channel layer is formed on the gate electrode. The first and the second source electrodes are extended from the data line to thereby overlap with one side of the channel layer. The drain electrode, which is in contact with the pixel electrode, is overlapped with the other side of the channel layer.

Description

TFT-LCD WITH TFT OF ASYMMETRY SOURCE / DRAIN STRUCTURE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor liquid crystal display device, and more particularly, to a thin film transistor liquid crystal display device having a thin film transistor having an asymmetric source / drain structure for preventing the deterioration of characteristics of the thin film transistor.

Thin Film Transistor Liquid Crystal Display (FT-LCD) has characteristics such as light weight, thinness, and low power consumption, so that it is a terminal or video of various information devices instead of CRT (Cathode-ray tube). Used in devices and the like, the TFT-LCD has excellent response characteristics and is suitable for high pixel numbers, so that it is expected to realize a high quality and large display device comparable to the CRT.

The TFT-LCD has a structure in which a TFT array substrate provided with a TFT and a pixel electrode, and a color filter substrate provided with a color filter and a counter electrode are bonded to each other under liquid crystal interposition.

1 is a plan view showing a TFT forming portion of a TFT-LCD formed according to the prior art, as shown, arranged so that the gate electrode 2a and the data line 8 intersect with each other under the interposition of a gate insulating film (not shown). In the pixel region defined by the gate line 2 and the data line 8, a pixel electrode 4 made of an ITO metal film is disposed, and the pixel line 4 of the gate line 2 and the data line 8 is disposed. At the intersection, a TFT 10 serving as a switching element is arranged.

Here, the TFT 10 includes a gate electrode 2a extending from the gate line 2 to the inside of the pixel region, and an undoped amorphous silicon layer disposed on the gate electrode 2a through a gate insulating film. A channel layer 3 comprising two first and second source electrodes 5a and 5b extending from the data line 8 and overlapping with an upper surface of one side of the channel layer 3 and the channel layer And a drain electrode 6 disposed to be in contact with the pixel electrode 4 while overlapping with the other upper surface of (3).

However, in the TFT having the above structure, since the first and second source electrodes and the drain electrode have a symmetrical structure, their characteristics and reliability are deteriorated.

That is, in the TFT having the above-described structure, a data signal is transmitted to the drain electrode 6 through the first and second source electrodes 5a and 5b, as shown, wherein the first source electrode 5a The second and second source electrodes 5b have the same width and length, and in particular, since the source electrodes 5a and 5b and the drain electrode 6 have a symmetrical structure, they are positioned relatively close to the data signal input unit. The carrier mobility on the side of the disposed first source electrode 5a becomes larger than the carrier mobility on the side of the second source electrode 5b disposed relatively far apart, and thus, the electric field at the first source electrode 5a. Is larger than the electric field in the second source electrode 5b. As a result, the electric field generated in the channel layer 3 becomes partially different. Therefore, this phenomenon causes deterioration in the portion of the channel layer in which a relatively large electric field is formed. As a result, the characteristics and reliability of the TFT are reduced. Degrades.

Accordingly, the present invention, which is devised to solve the above problems, differs in the width or length of the first source electrode and the second source electrode, so that the first source electrode part and the second source electrode part are different from each other. It is an object of the present invention to provide a TFT-LCD having a TFT having an asymmetric source / drain structure capable of preventing the deterioration of the characteristics of the TFT by making the electric field of the metal be balanced.

1 is a view illustrating a thin film transistor forming unit of a thin film transistor liquid crystal display device according to the related art.

2 is a diagram illustrating a thin film transistor forming unit of a thin film transistor liquid crystal display according to an exemplary embodiment of the present invention.

3A and 3B illustrate source electrodes of a thin film transistor according to another exemplary embodiment of the present invention.

4 is a view illustrating a thin film transistor forming unit of a thin film transistor liquid crystal display according to another exemplary embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

2: gate line 2a: gate electrode

3: channel layer 4: pixel electrode

5,5a, 5b: source electrode 6,6a, 6b: drain electrode

8,8a: data line 10: thin film transistor

A TFT-LCD having an asymmetric source / drain structure TFT of the present invention for achieving the above object includes a gate line and a data line arranged to cross each other under a gate insulating film; A pixel electrode disposed in the pixel region defined by the gate line and the data line; And a gate electrode disposed at an intersection of the gate line and the data line, the gate electrode extending from the gate line to the inside of the pixel area, a channel layer disposed on the gate electrode, and extending from the data line. The first and second source electrodes disposed at different distances from the data signal input part connected to the data line while overlapping the side surfaces, and overlapping with the other upper surface of the channel layer between the first source electrode and the second source electrode; In the TFT-LCD comprising a TFT consisting of a drain electrode in contact with the pixel electrode, the first source electrode and the second source electrode has a different size.

According to the present invention, the first source electrode and the second source electrode have the same length, and the second source electrode disposed relatively far from the data signal input unit is larger than the first source electrode disposed relatively close. In addition, the present invention provides a method in which a first source electrode and a second source electrode have the same width, and a first source electrode having a second source electrode disposed relatively far from the data signal input unit is disposed relatively close to each other. It has a longer length than the source electrode. In addition, the present invention allows the data line portion connected to the second source electrode to have a relatively wider width than the data line portion connected to the first source electrode.

According to the present invention, the first and second source electrodes and the drain electrode are made to have an asymmetrical structure so that an electric field at the first source electrode and the second source electrode portion is made uniform regardless of the distance from the data signal input unit. As a result, the degradation of the channel layer can be prevented, and the characteristics and reliability of the TFT can be ensured.

(Example)

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a plan view showing a TFT forming portion of a TFT-LCD according to an embodiment of the present invention. Here, the same parts as in Fig. 1 are designated by the same reference numerals.

As shown, a pixel region defined by the gate line 2 and the data line 8 intersect with each other under a gate insulating film (not shown), and defined by the gate line 2 and the data line 8. The pixel electrode 4 which consists of an ITO metal film is arrange | positioned inside.

At the intersection of the gate line 2 and the data line 8, a TFT 10 as a switching element is arranged. The TFT 10 includes a gate electrode 2a extending from the gate line 2 to the inside of the pixel region, a channel layer 3 disposed above the gate electrode 2a through a gate insulating film, and Two first and second source electrodes 5a and 5b extending from the data line 8 and overlapping with an upper surface of one side of the channel layer 3, and the other upper surface of the channel layer 3. A drain electrode 6 is disposed to overlap the pixel electrode 4 while being overlapped.

Here, the first and second source electrodes 5a and 5b and the drain electrode 6 of the TFT 10 according to the embodiment of the present invention are provided in an asymmetry structure. That is, the second source electrode 5b disposed relatively far from the data signal input part is provided to have a wider width than the first source electrode 5a disposed at a relatively close position, and the data line ( The lead portion in contact with 8) is also provided to have a relatively wide width at the second source electrode 5b side, and the width of the data line 8 connected to the second source electrode 5b is also relatively wide. It is provided to have a width. Accordingly, the resistance at the first source electrode 5a is larger than the resistance at the second source electrode 5b.

Therefore, when driving the TFT 10, the signal voltage input from the data signal input part is uniformly distributed by the resistance difference between the first source electrode 5a and the second source electrode 5b. Since the uniformly distributed voltage results in uniform carrier movement in the channel layer 3 and uniform electric field, consequently, due to the fact that no locally different electric field is formed in the channel layer, Deterioration does not occur, so that the characteristics and reliability of the TFT 10 can be ensured.

On the other hand, in the embodiment of the present invention, the resistance difference between the first source electrode 5a and the second source electrode 5b is generated in such a manner that the widths of the first source electrode 5a and the second source electrode 5b are different from each other. Although the signal voltage is uniformly distributed between the two source electrodes 5b, as another embodiment of the present invention, as shown in FIGS. 3A and 3B, the first source electrode 5a and the second source electrode are shown. A data line connected to the second source electrode 5b while varying the length between 5b or the length between the first source electrode 5a and the second source electrode 5b. The method of increasing the width (8) can also make the distribution of the data signal voltage uniform.

Further, as another embodiment of the present invention, the structure is different from the previous embodiments, but as shown in Fig. 4, only one source electrode 5 is provided, whereas from the portion in contact with the pixel electrode 4, It is also possible to configure the TFT 10 in a structure such that two drain electrodes 6a and 6b are branched. In this case, since the data signal voltage is transmitted through one source electrode 5, non-uniform distribution of signal voltage does not occur, and neither carrier mobility nor electric field unevenness occurs.

As described above, the present invention is configured such that the source electrode and the drain electrode of the TFT have an asymmetric structure, but the source electrode disposed at a relatively close position from the data signal input part has a greater resistance than the source electrode disposed relatively far away. By design, the distribution of the data signal voltage input through the source electrodes can be made uniform, thereby making the carrier mobility and the electric field formation in the channel layer uniform, resulting in the channel layer. By preventing deterioration of the TFT, the characteristics and the reliability of the TFT can be ensured.

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (6)

A gate line and a data line arranged to intersect with each other under a gate insulating film; A pixel electrode disposed in the pixel region defined by the gate line and the data line; And a gate electrode disposed at an intersection of the gate line and the data line, the gate electrode extending from the gate line to the inside of the pixel area, a channel layer disposed on the gate electrode, and extending from the data line. The first and second source electrodes disposed at different distances from the data signal input part connected to the data line while overlapping the side surfaces, and overlapping with the other upper surface of the channel layer between the first source electrode and the second source electrode; In the thin film transistor liquid crystal display device comprising a thin film transistor consisting of a drain electrode contacted with the pixel electrode, And the first source electrode and the second source electrode have different sizes. The method of claim 1, wherein the first source electrode and the second source electrode, The thin film transistor liquid crystal display device having the same length and having a larger width than the first source electrode disposed relatively close to the second source electrode disposed relatively far from the data signal input unit. The liquid crystal display of claim 2, wherein the data line portion connected to the second source electrode has a relatively wider width than the data line portion connected to the first source electrode. The method of claim 1, wherein the first source electrode and the second source electrode, The thin film transistor liquid crystal display device having the same width and having a longer length than the first source electrode disposed relatively close to the second source electrode disposed relatively far from the data signal input unit. The thin film transistor liquid crystal display of claim 4, wherein the data line portion connected to the second source electrode has a relatively wider width than the data line portion connected to the first source electrode. A gate line and a data line arranged to intersect with each other under a gate insulating film; A pixel electrode disposed in the pixel region defined by the gate line and the data line; And a gate electrode disposed at an intersection of the gate line and the data line, the gate electrode extending from the gate line to the inside of the pixel area, a channel layer disposed on the gate electrode, and one side of the channel layer extending from the data line. A source electrode disposed to overlap with an upper surface, and first and second contacts with the pixel electrode and branched from a portion contacted with the pixel electrode to overlap the other upper surface of the channel layer with the source electrode therebetween; A thin film transistor liquid crystal display comprising a thin film transistor comprising two drain electrodes.