KR20070025214A - Metal line for display substrate and display substrate having the same - Google Patents

Abstract

A metal line of a thin film transistor substrate and a thin film transistor substrate having the metal line are provided to reduce resistance of the metal line and improve reliability of the metal line by sequentially laminating an adhesive film, an Ag film and a passivation film made of AlNdNi to form the metal line. A metal line of a thin film transistor substrate includes an adhesive film, a low-resistivity metal film and a passivation film. The adhesive film is formed on an insulating substrate, and the low-resistivity metal film is formed on the adhesive film. The passivation film is formed of AlNdNi on the low-resistivity metal film. A thin film transistor substrate includes a plurality of pixels defined by gate lines extended in a first direction and source lines extended in a second direction, and switching elements(TFT) respectively formed at the pixels. The source lines and source and drain electrodes of the switching elements respectively include adhesive films(120a,160a), low-resistivity metal films(120b,160b) and passivation films(120c,160c) formed of AlNdNi.

Description

Metal wiring of a display substrate and a display substrate having the same {METAL LINE FOR DISPLAY SUBSTRATE AND DISPLAY SUBSTRATE HAVING THE SAME}

1 is a plan view of a display substrate according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.

3A through 3E are process diagrams illustrating a manufacturing process of the display substrate illustrated in FIG. 2.

4A to 4D are state diagrams showing mutual solid solubility between silver (Ag) and metal elements.

5 is experimental data observing the hillock properties of aluminum neodymium (AlNd) and aluminum neodymium nickel (AlNdNi).

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

100: display substrate 110: insulating substrate

120: gate metal pattern 120a: first adhesive layer

120b: first metal layer 120c: first protective layer

122: gate electrode 130: gate insulating film

140: active layer 160: source metal pattern

160a: second adhesive layer 160b: second metal layer

160c: first protective layer 164: source electrode

166: drain electrode

The present invention relates to a metal wiring of a display substrate and a display substrate having the same, and more particularly, to a metal wiring of a display substrate for reducing wiring resistance and a display substrate having the same.

A liquid crystal display (LCD) includes a liquid crystal layer injected between a thin film transistor substrate and a counter substrate. The liquid crystal layer is an anisotropic dielectric constant, and the image is displayed by adjusting the amount of light transmitted by changing the arrangement according to the intensity of the electric field.

The display substrate generally includes a switching element (TFT) formed on an insulating substrate, a gate wiring electrically connected to a gate electrode of the TFT, a source wiring electrically connected to a source electrode of the TFT, and a drain electrode of the TFT. And electrically connected pixel electrodes.

In general, the insulating substrate includes glass, and the gate electrode and the gate wiring include metal. The gate electrode and the gate wiring are disposed on the insulating substrate. Currently used pixel electrode materials include indium tin oxide (ITO) and indium tin oxide (IZO).

In recent years, with the increase in size and definition of liquid crystal display devices, the lengths of the gate lines and the data lines have increased, and conversely, the width has gradually decreased. As the length of the wiring increases and the width decreases, the wiring resistance increases relatively. When the wiring resistance increases, signal delay occurs, which degrades the display quality of the liquid crystal display device.

In order to solve this problem, silver (Ag), which is a metal having low resistivity, has been studied as a metal wiring of a display substrate.

However, silver (Ag) has a problem in that adhesion to an insulating substrate including glass is very low, so that wiring is easily separated from the insulating substrate. Therefore, there is a need for a lower adhesive layer to improve the adhesion between the silver (Ag) wiring and the insulating substrate.

In addition, silver (Ag) requires a top protective layer because agglomeration phenomenon or hillock occurs at a high process temperature and dry etching resistance is very poor. In general, molybdenum (Mo) or chromium (Cr) is mainly used as the upper protective layer of the metal wiring. However, since molybdenum (Mo) or chromium (Cr) has low adhesive strength with silver (Ag), when silver is used as the metal wiring, the reliability of the metal wiring is reduced.

Accordingly, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a metal wiring of a display substrate for reducing wiring resistance.

Another object of the present invention is to provide a display substrate having the metal wiring.

In order to achieve the above object of the present invention, the metal wiring of the display substrate according to the embodiment includes an adhesive layer, a low resistance metal layer, and a protective layer. The adhesive layer is formed on an insulating substrate, and the low resistance metal layer is formed on the adhesive layer. The protective layer is formed on the metal layer and is made of aluminum neodymium nickel (AlNdNi).

In accordance with another aspect of the present invention, a display substrate includes a plurality of pixel portions defined by gate wires extending in a first direction and source wires extending in a second direction, and each pixel portion. It includes a switching element formed in. The source and drain electrodes of the source wiring and switching element include a protective layer made of an adhesive layer, a low resistance metal layer, and aluminum neodymium nickel.

According to the metal wiring of the display substrate and the display substrate having the same, the wiring resistance can be reduced and the driving characteristics of the display substrate can be improved.

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

1 is a plan view of a display substrate according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II ′ of FIG. 1.

1 and 2, a display substrate according to an exemplary embodiment of the present invention may include an insulating substrate 110, a gate wiring GL, a switching element TFT, a source wiring DL, a passivation layer 170, and a pixel electrode. (PE).

The insulating substrate 110 is made of a transparent material through which light can be transmitted. For example, the insulating substrate 110 is made of glass.

The gate line GL is formed on the insulating substrate 110 and is connected to the gate electrode 122 of the switching element TFT. The gate lines GL extend in the horizontal direction and are arranged in the vertical direction.

The switching element TFT includes a gate electrode 122, a gate insulating layer 130, an active layer 140, a source electrode 164, and a drain electrode 166.

The gate electrode 122 extends from the gate line GL and is formed of the same gate metal pattern as the gate line GL. The gate metal pattern 120 has a three-layer film structure in which the first adhesive layer 120a, the first metal layer 120b, and the first protective layer 120c are sequentially stacked.

The first adhesive layer 120a is a layer formed to improve the adhesive force between the first metal layer 120b and the insulating substrate 110. The first adhesive layer 120a may be formed by diffusing the first metal layer 120b including silver (Ag) into the insulating substrate. prevent. The first adhesive layer 120a is made of any one selected from aluminum (Al), aluminum alloy, and indium oxide. Examples of the aluminum alloy that can be used as the first adhesive layer include AlNdNi or Al-Si or Al-Si-Cu. Indium oxides that may be used as the first adhesive layer include indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), and aluminum zinc oxide (AZO).

The first metal layer 120b is a layer serving as a path for an electric signal, which is a function of wiring, and is formed of silver (Ag) or silver alloy having a low specific resistance.

The first passivation layer 120c is a layer formed to protect the first metal layer 120b made of silver (Ag) or a silver alloy, and is made of aluminum neodymium nickel (AlNdNi) resistant to subsequent etching. The first protective layer also serves to prevent aggregation or hillock that occurs frequently in the silver (Ag) metal layer in a high temperature process.

The gate insulating layer 130 is formed on the insulating substrate 110 to cover the gate metal pattern 120. The gate insulating layer 130 is made of a silicon nitride film SiNx.

The active layer 140 is formed on the gate insulating layer 130 to correspond to the gate electrode 122. The active layer 140 includes a semiconductor layer 142 and an ohmic contact layer 144. For example, the semiconductor layer 142 is made of amorphous silicon (a-Si). The ohmic contact layer 144 is made of amorphous silicon (hereinafter, n + a-Si) doped with a high concentration of n-type impurities. The ohmic contact layer 144 is formed in an area overlapping the source electrode 164 and the drain electrode 166.

The source electrode 164 extends from the source wiring DL and is formed of the same source metal pattern as the source wiring DL.

The drain electrode 164 is formed of a source metal pattern and is electrically connected to the pixel electrode PE. The drain electrode 166 is spaced apart from the source electrode 164 and is formed on the gate insulating layer 130 on the opposite side of the source electrode 164 with respect to the gate electrode 122. The source electrode 164 corresponds to the source electrode 164 of the switching element TFT, and the drain electrode 166 corresponds to the drain electrode 166 of the switching element TFT.

The source wiring DL is formed as a source metal pattern on the gate insulating layer 130 to cross the gate wiring GL.

In the source metal pattern 160 including the source wiring DL, the source electrode 164, and the drain electrode 166, the second adhesive layer 160a, the second metal layer 160b, and the second protective layer 160c are sequentially formed. It has a three-layer film structure laminated.

The second adhesive layer 160a is a layer formed to improve ohmic contact characteristics and to improve adhesion to the gate insulating layer 130, and is formed of any one selected from aluminum, aluminum alloy, ITO, IZO, a-ITO, and AZO. . Examples of the aluminum alloy applicable to the second adhesive layer include AlNdNi or Al-Si or Al-Si-Cu. In particular, when the Al-Si alloy or Al-Si-Cu alloy is applied as the second adhesive layer, Si of the ohmic contact layer 144 is prevented from being diffused into the second adhesive layer, thereby eliminating the alloy spike phenomenon. Since it is possible, Al-Si alloy or Al-Si-Cu alloy is preferably applied.

The second metal layer 160b is a layer serving as a path for the electrical signal, which is a function of the wiring, and is formed of silver (Ag) or a silver alloy having a low specific resistance. Since silver (Ag) has good ohmic contact properties with a-Si, when an aluminum (Al) -silver (Ag) alloy is used as the second adhesive layer, improvement in ohmic properties can be expected.

The second protective layer 160c is a layer formed to protect the second metal layer 160b made of silver (Ag) or a silver alloy, and is made of AlNdNi. AlNdNi has strong dry etching resistance, thus protecting the second metal layer in a subsequent dry etching process of forming a pixel electrode. In addition, since AlNdNi has excellent Hilllock resistance, the AlNdNi prevents agglomeration or hillock frequently occurring in the silver (Ag) metal layer in a subsequent high temperature process.

 On the other hand, since the second protective layer 160c is a layer directly contacting ITO or IZO, which is a material of the pixel electrode PE, through the contact hole 172, the display substrate may be formed by using a material having a low contact resistance with the pixel electrode PE. It is possible to improve the driving characteristics.

Table 1 shows data for measuring contact resistance with IZO films of AlNd, AlNd / Mo, and AlNdNi metals.

AlNdNi-IZO AlNd-IZO AlNd / Mo-IZO Cr-IZO  Contact resistance 8.68E + 05 3.15E + 09 1.26E + 04 ~ E06

Referring to Table 1, the contact resistance of AlNdNi and IZO is much smaller than the contact resistance between AlNd and IZO, and is similar to the contact resistance between AlNd / Mo and IZO laminated with Mo as a contact layer or the contact resistance between Cr and IZO. You can see a small thing.

That is, by applying AlNdNi having a small contact resistance with the pixel electrode PE as the second passivation layer 160c, it is easy to form silver (Ag) wiring, which is a low resistance wiring, and improve driving characteristics of the display substrate.

The passivation layer 170 is formed on the insulating substrate 110 to cover the source metal pattern 160 and the gate insulating layer 130. A contact hole 172 is formed in the passivation layer 170 to expose the drain electrode 166.

The pixel electrode PE is formed on the passivation layer 170 and is electrically connected to the drain electrode 166 through the contact hole 172. The pixel electrode 180 is made of a transparent conductive material through which light can pass. For example, transparent conductive materials include ITO and IZO.

Although not shown, the storage common wiring may be formed of the gate metal pattern of the display substrate.

Hereinafter, a method of manufacturing a display substrate according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3A to 3E.

3A through 3E are process diagrams illustrating a manufacturing process of the display substrate illustrated in FIG. 2.

Referring to FIG. 3A, the first adhesive layer 120a, the first metal layer 120b, and the first passivation layer 120c are sequentially stacked on the insulating substrate 110, and the gate wiring GL and the gate are etched through an etching process. A gate metal pattern 120 including the electrode 122 is formed. The first adhesive layer 120a, the first metal layer 120b, and the first protective layer 120c may be simultaneously etched through a wet etching process.

The first adhesive layer 120a is a layer formed to improve the adhesion between the first metal layer and the insulating substrate 110. The first adhesive layer 120a has excellent adhesion to the insulating substrate and also has excellent adhesion to the silver (Ag) metal layer. ), Aluminum alloy, ITO, IZO, a-ITO, AZO selected from any one. Examples of the aluminum alloy that can be used as the first adhesive layer include AlNdNi, Al-Si, and Al-Si-Cu.

The first metal layer 120b is made of silver (Ag) having low specific resistance or an alloy including silver.

The first protective layer 120c is a layer formed to protect the first metal layer 120b and is made of aluminum neodymium nickel (AlNdNi).

Referring to FIG. 3B, a gate insulating layer 130 made of silicon nitride layer SiNx is formed on the insulating substrate 110 on which the gate metal pattern 120 is formed.

Subsequently, the semiconductor layer 142 and the ohmic contact layer 144 are sequentially stacked on the gate insulating layer 130, and the active layer 140 is formed to overlap the gate electrode 122 through an etching process. The semiconductor layer 142 is made of a-Si, and the ohmic contact layer 144 is made of n + a-Si doped with a high concentration of n-type impurities.

Referring to FIG. 3C, the second adhesive layer 160a, the second metal layer 160b, and the second protective layer 160c are sequentially stacked on the gate insulating layer 130, and the source wiring DL and the source are etched through an etching process. The source metal pattern 160 including the electrode 164 and the drain electrode 166 is formed. The second adhesive layer 160a, the second metal layer 160b, and the second protective layer 160c may be simultaneously etched through a wet etching process. The drain electrode 166 is spaced apart from the source electrode 164 and is formed on the opposite side of the source electrode 164 around the gate electrode 122.

The second adhesive layer 160a is a layer formed to improve ohmic contact characteristics and to improve adhesion to the gate insulating layer 130, and is formed of any one selected from indium oxide, aluminum (Al), and aluminum alloy. Indium oxides applicable to the second adhesive layer include ITO, IZO, a-ITO, and AZO. Aluminum alloys applicable to the second adhesive layer include, for example, AlNdNi, Al-Si, and Al-Si-Cu. In particular, when the Al-Si alloy or Al-Si-Cu alloy is applied as the second adhesive layer, the silicon (Si) of the ohmic contact layer 144 is prevented from being diffused into the second adhesive layer, thereby alloy spike The phenomenon can be eliminated.

The second metal layer 160b is made of silver (Ag) having low specific resistance or an alloy including silver.

The second passivation layer 160c is a layer formed to protect the second metal layer 160b. The second passivation layer 160c is made of aluminum neodymium nickel (AlNdNi), which is strong in dry etching, has excellent hillock resistance, and has low contact resistance with the pixel electrode. Is done.

Thereafter, the ohmic contact layer 144 is etched using the source and drain electrodes 164 and 166 as masks to expose the semiconductor layer 142.

Referring to FIG. 3D, the passivation layer 170 is formed on the gate insulating layer 130 on which the gate metal pattern 120 and the source metal pattern 160 are formed.

 Subsequently, the passivation layer 170 is patterned through an etching process to form a contact hole 172 for exposing the drain electrode 166. The contact hole 172 may be formed in an angle shape or a circular shape.

Referring to FIG. 3E, a transparent conductive layer (not shown) is deposited on the passivation layer 170, and the pixel electrode PE is formed through an etching process.

The etching process of forming the contact hole or the pixel electrode may be performed by both wet etching and dry etching. However, the aluminum neodymium nickel layer, which is the second protective layer, has a strong dry etching resistance, and therefore, preferably, a dry etching process is performed.

The pixel electrode PE is electrically connected to the drain electrode 166 through the contact hole 172. The pixel electrode PE is made of a transparent conductive material through which light can pass. For example, the pixel electrode 180 is made of ITO or IZO.

Meanwhile, in the present embodiment, both the gate metal pattern and the source metal pattern have a three-layer film structure, but only one of the gate metal pattern and the source metal pattern may have a three-layer film structure as needed.

4A to 4D are state diagrams showing mutual solid solubility between silver (Ag) and metal elements.

Silver (Ag) has poor adhesion with metals such as Mo, Ti, and W, but has good adhesion with indium oxides such as ITO and IZO, so that ITO or IZO is used as the adhesive layer. This is attributable to the low adhesion with silver (Ag) materials and the high adhesion with silver (Ag) materials.

Referring to FIG. 4A, silver (Ag) does not show mutual solid solubility with molybdenum (Mo) at 300 degrees Celsius.

Referring to FIG. 4B, silver (Ag) does not show mutual solid solution with chromium (Cr) at 300 degrees Celsius.

That is, since Mo and Cr do not have a solid solubility with silver (Ag), it is difficult to apply it as an adhesive layer of the silver (Ag) metal layer because the adhesion with silver (Ag) is very low.

Referring to FIG. 4C, silver (Ag) exhibits mutual solid solubility of indium (In) and 20 at% (atomic percent) at 300 degrees Celsius.

Referring to FIG. 4D, silver (Ag) exhibits about 15% mutual solid solubility with aluminum (Al) at 300 degrees Celsius.

That is, although the solubility between silver (Ag) and indium (In) is lower than that of silver (Ag) and aluminum (Al), the solubility between silver (Ag) and aluminum (Al) is also very high, so that the adhesion between silver (Ag) and aluminum (Al) is also high. it means.

Therefore, by forming the first adhesive layer 120c made of aluminum (Al) or an aluminum alloy under the first metal layer 120b including silver (Ag), the silver (Ag) wiring with increased adhesion to the insulating substrate is increased. Can be formed.

5 is experimental data comparing and observing Hillock properties of aluminum neodymium (AlNd) and aluminum neodymium nickel (AlNdNi).

Referring to FIG. 5, when 30 minutes (0.5h) to one hour (1h) of the heat treatment at 330 degrees Celsius have been started, as in the AlNd metal wiring as the comparative example, the hillock is also used in the AlNdNi metal wiring as an example. This did not happen. In other words, AlNdNi metal wires also have high hillock resistance at high temperatures, so that when used as a protective layer, the aggregation of silver metal layers or the hillock phenomenon can be controlled.

As described above, the display substrate according to the present invention includes a metal wiring in which an adhesive layer, a low resistance silver (Ag) metal layer, and a protective layer made of AlNdNi are sequentially formed. AlNdNi used as the protective layer has excellent adhesion with silver (Ag), thereby improving the reliability of the metal wiring. In addition, the dry etching resistance is strong, the contact resistance with the pixel electrode is low, and the hillock generation and aggregation of the silver (Ag) metal layer in the high temperature process can be prevented.

The aluminum alloy to indium oxide used as the adhesive layer may improve the adhesion between the silver (Ag) metal layer and the insulating substrate, thereby preventing silver (Ag) from diffusing into the insulating substrate, thereby improving reliability of the metal wiring.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (7)

An adhesive layer formed on the insulating substrate; A low resistance metal layer formed on the adhesive layer; And And a protective layer formed on the metal layer and made of aluminum neodymium nickel (AlNdNi). The metal line of claim 1, wherein the metal layer is made of silver (Ag) or a silver alloy. The metal line of claim 1, wherein the adhesive layer is one selected from AlNdNi, Al-Si, Al-Si-Cu, Al, ITO, IZO, a-ITO, and AZO. In a display substrate including a plurality of pixel portions defined by gate wiring lines extending in a first direction and source wiring lines extending in a second direction, and a switching element formed in each pixel portion, The source and drain electrodes of the source wiring and the switching element may include a protective layer made of an adhesive layer, a low resistance metal layer, and aluminum neodymium nickel. The display substrate of claim 4, wherein the gate line and the gate electrode of the switching element include a protective layer made of the adhesive layer, the low resistance metal layer, and aluminum neodymium nickel. The display substrate of claim 4, wherein the low resistance metal layer is made of silver or a silver alloy. The display substrate of claim 4, wherein the adhesive layer is one selected from AlNdNi, Al-Si, Al-Si-Cu, Al, ITO, IZO, a-ITO, and AZO.

Images