KR20060077733A - Thin film transistor array panel - Google Patents

Abstract

The present invention relates to a thin film transistor in which protrusions are formed on the sustain electrode to increase the surface area.

By forming protrusions on the sustain electrode, the surface area can be increased to increase the capacitance of the sustain capacitor, thereby reducing the width of the sustain electrode, thereby improving the aperture ratio.

Sustain electrodes, projections, pixel electrodes, capacitors

Description

Thin Film Transistor Display Panels {THIN FILM TRANSISTOR ARRAY PANEL}

1 is a layout view of a thin film transistor array panel for a liquid crystal display according to another exemplary embodiment of the present invention.

2 and 3 are cross-sectional views of the thin film transistor array panel illustrated in FIG. 1 taken along lines II-II 'and III-III', respectively.

<Explanation of symbols for the main parts of the drawings>

110: insulating substrate 121: gate line

124: gate electrode 133a: sustain electrode vertical portion

133b: sustain electrode horizontal portion 133c: connection portion

133d: sustain electrode projection

140: gate insulating film 151, 154: semiconductor

161, 163, and 165: ohmic contact layer 171: data line

173: source electrode 175: drain electrode

180: protective film 190: pixel electrode

182, 185, 189: contact hole 81, 82: contact auxiliary member

The present invention relates to a thin film transistor array panel having a sustain electrode.

The display device is a device that provides information through an image. Among them, a liquid crystal display device and an organic EL display device are in the spotlight as a flat panel display device. Among them, a liquid crystal display device generally includes an upper substrate and a thin film transistor on which a common electrode and a color filter are formed. And a liquid crystal material are injected between the lower substrate where the pixel electrode and the like are formed, and different electric potentials are applied to the pixel electrode and the common electrode to form an electric field to change the arrangement of the liquid crystal molecules, thereby adjusting the light transmittance. It is a device that represents an image.

The lower substrate of the thin film transistor array panel includes a gate line for transmitting a scan signal and a data line for transmitting an image signal, and covers a thin film transistor connected to the gate line and the data line, a pixel electrode connected to the thin film transistor, and a gate line. A gate insulating film for insulating and a protective film for covering and insulating the thin film transistor and the data line. The thin film transistor includes a semiconductor forming a gate electrode and a channel as part of a gate line, a source electrode and a drain electrode as part of a data line, a gate insulating film, a protective film, and the like. The thin film transistor is a switching device that transfers or blocks an image signal transmitted through a data line to a pixel electrode according to a scan signal transmitted through a gate line.

When the image signal is transmitted to the pixel electrode through the thin film transistor, the pixel electrode forms an electric field with the common electrode of the upper substrate, and the liquid crystal rotates due to the electric field. As the liquid crystal rotates, the transmittance of light changes, thereby displaying an image.

Once rotated, the liquid crystal must be maintained to maintain the same angle until the next signal is applied. For this purpose, a separate holding capacitor must be formed for each pixel. However, such a capacitor is formed through a separate wiring, so that the opening ratio of the pixel region is reduced.

An object of the present invention is to provide a thin film transistor including a sustain electrode having a structure having a sufficiently large capacitance even with a narrow width.

In order to solve this problem, the present invention provides a thin film transistor having a wide surface area by forming protrusions on the sustain electrode.

Specifically, a gate line formed on an insulating substrate, the gate line including a gate electrode, a gate insulating film formed separately from the gate line, and having a protrusion formed on a surface thereof, and covering the gate line and the sustain electrode. A semiconductor formed on a gate insulating film, a data line defining a pixel region crossing the gate line and including a source electrode, a drain electrode facing the source electrode at a predetermined distance on the semiconductor, and a first electrode exposing the drain electrode. A thin film transistor array panel including a passivation layer having a contact hole and a pixel electrode formed on the passivation layer and connected to the drain electrode through the first contact hole.                     

The storage electrode may include two vertical parts and two horizontal parts inside the pixel area, and may be connected to the storage electrodes of adjacent pixels through a connection part.

The protrusion is preferably formed linearly along the horizontal direction,

Preferably, the pixel electrode has a curvature due to the protrusion of the sustain electrode.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A thin film transistor array panel according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a layout view of a thin film transistor array panel for a liquid crystal display according to another exemplary embodiment of the present invention, and FIGS. 2 and 3 illustrate the thin film transistor array panel shown in FIG. 1, along with lines II-II 'and III-III', respectively. It is a cross-sectional view cut along.

A gate signal is transmitted on the insulating substrate 110, and a plurality of gate lines 121 extending mainly in a horizontal direction are formed.

A portion of each gate line 121 forms a plurality of gate electrodes 124. In addition, each gate line 121 includes an extension 125 extending in width for connection with an external device. Most of the gate line 121 is located in the display area, but the extension 125 of the gate line 121 is located in the peripheral area.

A plurality of sustain electrodes 133 electrically separated from the gate lines 121 are formed. The storage electrode 133 includes two horizontal portions 133b and two vertical portions 133a in one pixel, and protrudes from the vertical portions 133a to be connected to the storage electrodes of the next pixel ( 133c).

The storage electrode horizontal portion 133b is formed horizontally by being separated from the gate line 121 in the pixel region adjacent to the gate line 121 at the front end and the gate line 121 at the main stage, and the storage electrode vertical portion 133a is formed at the front end. The pixel region adjacent to the data line 171 is formed on the right side of the data line 171 and the left side of the data line 171 of the main stage so as not to overlap the data line 171. However, it may partially overlap the branch portion protruding from the data line 171 and extending toward the drain electrode 175.

Two connecting portions 133c protrude from the storage electrode vertical portion 133a and are electrically connected to the storage electrode 133 of the next pixel through the two connecting portions 133c.

On the other hand, projections 133d are formed on the surfaces of the horizontal portion 133b and the vertical portion 133a of the sustain electrode. In this embodiment, the projection 133d is formed linearly along the horizontal direction. Therefore, in the sustain electrode vertical portion 133a, protrusions 133d having a length shorter than the width of the sustain electrode vertical portion 133a are formed, but the protrusions long as the length of the sustain electrode horizontal portion 133b are formed in the sustain electrode horizontal portion 133b. 133d is formed.

The number, direction, and shape of the protrusions 133d may be formed differently according to embodiments.

The sustain electrode 133 receives a predetermined voltage such as a common voltage from the outside.

In addition, side surfaces of the gate line 121 and the storage electrode 133 are inclined, respectively, and the inclination angle of the gate line 121 and the storage electrode 133 is about 30 to 80 degrees with respect to the surface of the substrate 110.

The gate insulating layer 140 made of silicon nitride (SiNx) is formed on the gate line 121 and the storage electrode 133.

A plurality of linear semiconductors 151 made of hydrogenated amorphous silicon or the like are formed on the gate insulating layer 140, and the linear semiconductors 151 mainly extend in the vertical direction, and extend in the form of branches from the gate electrode 124. A plurality of protrusions 154 covering the tops are formed.

A plurality of linear and island resistive contact members 161 and 165 made of a material such as n + hydrogenated amorphous silicon in which silicide or n-type impurities are heavily doped is formed on the semiconductor 151. The linear contact member 161 has a plurality of protrusions 163, and the protrusions 163 and the island contact members 165 are paired and positioned on the protrusions 154 of the semiconductor 151.

 Side surfaces of the semiconductor 151 and the ohmic contacts 161 and 165 are also inclined, and the inclination angle is 30 to 80 degrees.

A plurality of data lines 171 and a plurality of drain electrodes 175 are formed on the ohmic contacts 161 and 165 and the gate insulating layer 140, respectively.

The data line 171 mainly extends in the vertical direction and crosses the gate line 121 to transmit a data voltage. Each data line 171 includes an expansion unit 179 which is extended in width for connection with an external device. Most of the data line 171 is located in the display area, but the extension 179 of the data line 171 is located in the peripheral area.

A plurality of branches extending in a branch shape from each data line 171 toward the drain electrode 175 forms the source electrode 173. The pair of source electrode 173 and the drain electrode 175 are separated from each other and positioned opposite to the gate electrode 124. The gate electrode 124, the source electrode 173, and the drain electrode 175 form a thin film transistor together with the protrusion 154 of the semiconductor 151, and the channels of the thin film transistor are the source electrode 173 and the drain electrode 175. It is formed in the projection 154 therebetween.

Similar to the gate line 121 and the storage electrode 133, the data line 171 and the drain electrode 175 are inclined at an angle of about 30 to 80 degrees.

The ohmic contacts 161 and 165 exist only between the lower semiconductor 151, the upper data line 171, and the drain electrode 175 and lower the contact resistance. The linear semiconductor 151 has a portion exposed between the data line 171 and the drain electrode 175, including between the source electrode 173 and the drain electrode 175.

On the data line 171, the drain electrode 175, and the exposed portion of the semiconductor 151, an organic material having excellent planarization characteristics and photosensitive characteristics, a formed of plasma enhanced chemical vapor deposition (PECVD) A protective film 180 made of a low dielectric constant insulating material having a dielectric constant of 4.0 or less, such as -Si: C: O, a-Si: O: F, or silicon nitride, which is an inorganic material, is formed. In this embodiment, the passivation layer 180 may be formed using an organic material having excellent planarization characteristics, but silicon nitride, which is an inorganic material, rather than an organic material, may be used to increase the capacitance between the sustain electrode 133 and the pixel electrode 190. It is more preferable to form the surface of the protective film 180 is not flat using.

In the passivation layer 180, a plurality of contact holes 185 and 189 respectively exposing the drain electrode 175 and the extension 179 of the data line 171 are formed, and the gate line 121 together with the gate insulating layer 140 is formed. A plurality of contact holes 182 are formed to expose the extension 125 of.

A plurality of pixel electrodes 190 and a plurality of contact auxiliary members 81 and 82 are formed on the passivation layer 180.

The pixel electrode 190 is made of ITO or IZO, and has a structure having a bend along the step of the passivation layer 180.

The pixel electrode 190 is physically and electrically connected to the drain electrode 175 through the contact hole 185 to receive a data voltage from the drain electrode 175.                     

The pixel electrode 190 to which the data voltage is applied rearranges the liquid crystal molecules of the liquid crystal layer between the two electrodes by generating an electric field together with the common electrode of another display panel to which the common voltage is applied.

In addition, the pixel electrode 190 and the common electrode form a capacitor to maintain the applied voltage even after the thin film transistor is turned off. In order to enhance the voltage holding capability, another capacitor connected in parallel with the liquid crystal capacitor is provided and the “storage capacitor” electrode) ". The storage capacitor is made by overlapping the storage electrode 133 and the pixel electrode 190, and the structure of the storage electrode 133 and the capacitance of the storage capacitor, which are the core of the present invention, will be described later.

The pixel electrode 190 also overlaps the neighboring gate line 121 and the data line 171 to increase the aperture ratio, but may not overlap.

The contact auxiliary members 81 and 82 are connected to the extension part 125 of the gate line and the extension part 179 of the data line through contact holes 182 and 189, respectively. The contact assistants 81 and 82 serve to protect adhesion between the extension portions 125 and 179 of the gate line 121 and the data line 171 and the external device.

The contact auxiliary members 81 and 82 are also made of ITO or IZO like the pixel electrode 190.

Hereinafter, the capacitance of the storage capacitor constituting the sustain electrode 133 and the pixel electrode 190 which are the core of the present invention will be described in detail with reference to FIG. 2.

The layer structure of the sustain electrode vertical portion 133a shown in FIG. 2 is as follows.                     

The gate insulating layer 140, the passivation layer 180, and the pixel electrode 190 are sequentially stacked on the storage electrode vertical portion 133a.

In general, the capacitance of a capacitor is obtained using the following equation.

Where C is the capacitance, ε is the permittivity, A is the area, and d is the distance.

The sustain electrode 133 is formed to include linear protrusions as in the present invention, and the pixel electrode 190 is formed to have a curvature along the shape of the sustain electrode 133, where ε and d do not change, but A is not changed. Increases. As the surface area increases, the C (capacitance) value increases.

As a result, the width of the wiring constituting the sustain electrode 133 can be reduced while having the same capacitance, thereby increasing the aperture ratio of the display device.

There are various methods of forming the sustain electrode 133 having such protrusions 133d.

Since the storage electrode 133 is formed on the same layer as the gate line 121 and is stacked and patterned together with the gate line 121, the storage electrode 133 may be formed using two masks.

One mask has the height of the protrusion 133d, and the width is patterned to have the width of the gate line 121 and the storage electrode 133, respectively, and then another portion of the gate line 121 is formed by using a mask. The gate line 121 may be formed by etching the entire surface, and the storage electrode 133 may be formed to have the protrusion 133d by etching only a portion of the sustain electrode 133 by using a mask.

In addition to the above method, there may be a method of forming protrusions by forming a storage electrode 133 having a height of about the gate line 121 together with the gate line 121 and then stacking and patterning a material only on the storage electrode 133. Can be.

Unlike the illustrated embodiment, the protrusion 133d of the present invention may have a linear protrusion 133d formed vertically, and may have various other shapes.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, by forming the protrusion on the sustain electrode, the surface area can be increased to increase the capacitance of the sustain capacitor, thereby reducing the width of the sustain electrode, thereby improving the aperture ratio.

Claims (4)

A gate line formed on the insulating substrate and including a gate electrode, A sustain electrode formed separately from the gate line and having protrusions formed on a surface thereof; A gate insulating film covering the gate line and the sustain electrode, A semiconductor formed on the gate insulating film, A data line defining a pixel region crossing the gate line and including a source electrode, A drain electrode facing the source electrode at a predetermined interval on the semiconductor, A protective film having a first contact hole exposing the drain electrode, And a pixel electrode formed on the passivation layer and connected to the drain electrode through the first contact hole. In claim 1, The storage electrode includes two vertical parts and two horizontal parts inside the pixel area, and is connected to the storage electrodes of adjacent pixels through a connection part. In claim 1, The protrusion is formed in a linear form along the horizontal direction. In claim 1, The pixel electrode is curved due to the protrusion of the sustain electrode.

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