KR101490452B1 - Display Device and Method for fabricating the same - Google Patents

Abstract

The present invention relates to a display device for preventing leaching of alkali ions onto soda lime glass and forming a transparent conductive layer for use as a pixel electrode and a method of manufacturing the same, wherein the array substrate of the liquid crystal display device comprises a substrate containing alkali ions; A transparent conductive layer formed on the substrate and used as a pixel electrode to prevent leaching of the alkali ion; An insulating film formed on the zinc oxide layer and having a contact hole; And a thin film transistor connected to the zinc oxide layer through the contact hole and formed on the insulating film.

Soda lime substrate, alkali, leach prevention film, transparent conductive layer, pixel electrode

Description

DISPLAY DEVICE AND METHOD FOR MANUFACTURING THE SAME

More particularly, the present invention relates to a display device for preventing the leaching of alkali ions onto a soda lime glass and forming a transparent conductive layer for use as a pixel electrode, and a manufacturing method thereof .

As the information society develops, the demand for display devices for displaying images has been increasing in various forms, and liquid crystal display (LCD), plasma display panel (PDP), electro luminescent display (ELD) display) and the like have been utilized. Among the display devices, liquid crystal display devices are widely used today because they have advantages of miniaturization, light weight, thinness, and low power driving. A liquid crystal display device is constituted by interposing a liquid crystal between two substrates facing each other. In general, a liquid crystal display device is driven in such a manner that an image is displayed by changing a liquid crystal array by an electric field generated between a pixel electrode formed on two substrates and a common electrode.

FIG. 1 is a schematic view of a conventional liquid crystal display, and FIG. 2 is a cross-sectional view of an array substrate according to the prior art.

1, the conventional liquid crystal display device 11 includes an upper substrate 5, a lower substrate 10, and a liquid crystal 9 interposed between the upper substrate 5 and the lower substrate 10 . The upper substrate 5 includes a plurality of color filters 7 in which red, green, and blue are arranged, a black matrix 6 formed between the plurality of color filters 7, and a plurality of color filters 7 And includes a common electrode 18 on the black matrix 6. The lower substrate 10 includes a pixel region P, a pixel electrode 36 formed on the pixel region P, and a thin film transistor T. [ The lower substrate 10 is referred to as an array substrate. The thin film transistor T which is a switching element is located at the intersection of the gate wiring 14 and the data wiring 22 and the pixel region P is defined by the intersection of the gate wiring 14 and the data wiring 22. [ On the pixel region P, a pixel electrode 36 made of a transparent material is formed.

2 is a sectional view of an array substrate on which a thin film transistor is formed, and the thin film transistor is formed by the following process sequence.

Aluminum (Al) or an aluminum alloy (AlNd) is deposited and patterned as a first metal on the lower substrate 10 using a transparent soda lime glass to form a gate electrode 30 ). A gate insulating film 32 formed of a silicon oxide film or a silicon nitride film is formed on the lower substrate 10 including the gate electrode 30 and the gate wiring. An amorphous silicon layer is formed on the gate insulating film 32. After the impurity is doped in the amorphous silicon layer, patterning is performed to form an active layer 40, which is an amorphous silicon layer not doped with impurities, and an amorphous silicon layer, A contact layer 42 is formed. The semiconductor layer 44 including the active layer 40 and the ohmic contact layer 42 is referred to as a semiconductor layer.

Aluminum (Al) or an aluminum alloy (AlNd) is deposited as a second metal on the gate insulating film 32 including the semiconductor layer 44 and patterned to form the data line 22 and the semiconductor layer 44 and the source electrode 46 and the drain electrode 48, which are spaced apart from each other. The ohmic contact layer 42 between the source electrode 46 and the drain electrode 48 is removed and the active layer 40 is exposed to expose the gate electrode 30 between the source electrode 46 and the drain electrode 48, And a channel region 50 is formed in the corresponding semiconductor layer 44.

A protective layer 52 is formed of an insulating material on the gate insulating film 32 including the source electrode 46, the drain electrode 48 and the data line 22. [ A source contact hole 54 is formed by etching the protective layer 52 corresponding to the source electrode 46 and a transparent conductive film is formed on the protective layer 52 including the source contact hole 54 and patterned, And a pixel electrode 56 electrically connected to the electrode 46 is formed. A plurality of color filters 7 in which red, green, and blue are arranged, a black matrix 6 formed between the plurality of color filters 7, and a plurality of color filters 7 and black matrices 6 The upper substrate 5 having the common electrode 18 formed thereon is bonded to the lower substrate 10 to complete the liquid crystal display device.

In the above-described liquid crystal display device, the upper and lower substrates 5 and 10 use a non-alkali glass made of a transparent and insulating material. Generally, glasses are classified into alkali-free glass, soda lime glass, and borosilicate glass. Wherein the soda lime glass is a glass having an Na ₂ O content of 1 wt% or more, the alkali-free glass has a Na ₂ O content of 0.1 wt% or less, and the borosilicate glass has a Na ₂ O content of 0.1 wt% to be. Here, soda lime glass is called alkali glass.

Non-alkali glass is mainly used for an active type liquid crystal display device including a thin film transistor. Since soda lime glass contains a large amount of alkali ion, alkali ion easily leaches out during the high temperature process during the manufacturing process of liquid crystal display device. Therefore, when the soda lime glass array substrate is manufactured, the alkali ion diffused in the soda lime glass, The channel region using the semiconductor layer is contaminated. By changing the conductance property of the semiconductor property of the channel region by the alkali leached into the active region, the leakage current Ioff is increased by conducting the source and drain electrodes in the channel region even when the gate voltage is turned off . In addition, when the contamination by the alkali ions to the liquid crystal occurs, the after-image problem may be caused.

Therefore, since the alkali-free glass substrate does not leach alkali ions and causes no problems with the above, general liquid crystal display devices are manufactured using a non-alkali substrate. However, the non-alkali substrate is 5 times more expensive than soda lime glass. Although the liquid crystal display device has advantages of thin film and light weight in comparison with other display devices, the cost of the glass, which occupies a large portion in the price among the parts or materials to be manufactured, In order to reduce it, we are seeking to use soda lime glass instead of non-alkali glass.

It is an object of the present invention to provide a display device for preventing leaching of alkali ions on a soda lime glass and forming a transparent conductive layer to be used as a pixel electrode and a method of manufacturing the same.

It is another object of the present invention to provide a display device and a method of manufacturing the same that prevent leaching of alkali ions onto a soda lime glass and dope impurities to improve the electrical conductivity of a projection conductive layer used as a pixel electrode do.

According to an aspect of the present invention, there is provided an array substrate of a liquid crystal display device including: a substrate including an alkali ion; A transparent conductive layer formed on the substrate and used as a pixel electrode to prevent leaching of the alkali ion; An insulating film formed on the zinc oxide layer and having a contact hole; And a thin film transistor connected to the zinc oxide layer through the contact hole and formed on the insulating film.

In the above-described array substrate of the liquid crystal display device, the thin film transistor may include: a source electrode formed on the insulating film and connected to the pixel electrode through the contact hole; A drain electrode spaced apart from the source electrode and formed on the insulating film; A semiconductor layer formed on the insulating film including the source electrode and the drain electrode and having a channel region; A gate insulating film on the semiconductor layer; And a gate electrode on the gate insulating film corresponding to the channel region.

In the above-described array substrate of the liquid crystal display device, the transparent conductive layer is a zinc oxide layer.

In the above-described array substrate of the liquid crystal display device, the zinc oxide layer is formed to have a thickness of 0.5 to 2 탆.

In the above-described array substrate of the liquid crystal display device, the zinc oxide layer is doped with boron or aluminum.

In the above-described array substrate of the liquid crystal display device, the substrate is a sodalime glass.

According to another aspect of the present invention, there is provided a method of manufacturing an array substrate in a liquid crystal display device, comprising: preparing a substrate including an alkali ion; Preventing leaching of the alkali ion on the substrate and forming a transparent conductive layer used as a pixel electrode; Forming an insulating film on the transparent conductive layer; Forming a contact hole on the insulating film; And forming a thin film transistor connected to the transparent conductive layer through the contact hole.

In the above-described method for manufacturing an array substrate in a liquid crystal display device, the transparent conductive layer is formed of a zinc oxide layer, and the zinc oxide layer is formed of diethylzinc or dimethylzinc, And the like.

In the above-described method for manufacturing an array substrate in a liquid crystal display device, the zinc oxide layer is formed at a deposition rate of 2000 Å / mim and a temperature of 200 ° C.

In the above-described method of manufacturing an array substrate in a liquid crystal display device, the method includes the step of doping the zinc oxide layer with boron or aluminum as an impurity.

In the above-described method for manufacturing an array substrate in a liquid crystal display device, B ₂ H ₃ is used as the source of boron and trimethylaluminum (TMA) (Al (CH ₃ ) ₃ ) is used as the source of aluminum .

According to an aspect of the present invention, there is provided a liquid crystal display device including: a lower substrate including an alkali ion; a transparent conductive layer formed on the lower substrate to prevent leaching of the alkali ion and used as a pixel electrode; An insulating film formed on the insulating film and having a contact hole, and a thin film transistor formed on the insulating film and connected to the transparent conductive layer through the contact hole; And a color filter substrate bonded to the array substrate, the color filter substrate including an upper substrate including an alkali ion, a color filter on the upper substrate, and a common electrode on the color filter.

In the above-described liquid crystal display device, a zinc oxide layer is formed on the color filter, and a second insulating film is formed between the zinc oxide layer and the common electrode.

The substrate of the display device according to the present invention has the following effects.

By forming a zinc oxide layer on the soda lime glass as a leaching prevention film, a soda lime glass which is five times or more cheaper than a non-alkali substrate without using a non-alkali substrate as a substrate of a display device, particularly a liquid crystal display device It can be used, and cost competitiveness can be secured.

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

FIGS. 3A to 3E are cross-sectional views illustrating a process sequence of an array substrate of a liquid crystal display device according to the present invention, and FIGS. 4A to 4C are cross-sectional views illustrating a process sequence of a color filter substrate of a liquid crystal display device according to the present invention .

The manufacturing process of the lower substrate on which the thin film transistor is formed is as follows. As shown in FIG. 3A, the lower substrate 110 is divided into a pixel region P and a thin film transistor region T. A soda lime glass having a Na ₂ O content of 1 wt% or more is prepared as a lower substrate 110 and a zinc oxide (ZnO) layer is formed as a transparent conductive layer 112 on the lower substrate 110. For example, boron or aluminum is doped to improve the electrical conductivity of the zinc oxide layer. The zinc oxide layer has electrical conductivity and is transparent. The zinc oxide layer also prevents leaching to prevent the leaching of alkali metal ions from the soda lime glass.

The zinc oxide layer is formed by injecting diethylzinc or dimethylzinc as a source material and a substance containing oxygen as a reactant such as steam (H2O) or ozone (O3) . The zinc oxide layer may be formed using chemical vapor deposition (CVD), E-beam evaporation, sputtering, thermal evaporation, or the like. The deposition rate of the zinc oxide layer is about 2000 angstroms / mim, and the deposition temperature is approximately 200 degrees or less. The resistivity of zinc oxide is approximately 10 < ^-3 > OMEGA cm and doped with boron or aluminum to have a sufficient sheet resistance as a pixel electrode, and is formed to a thickness of 0.5 to 2 mu m. The sheet resistance of the transparent conductive layer 112 is 10 to 100 Ω / □. When the zinc oxide layer is doped with boron, B ₂ H ₃ is used as a source, and when doping with aluminum, trimethylaluminum (TMA) (Al (CH ₃ ) ₃ ) is used as a source.

3B, a lower lower insulating film 114 is formed on the transparent conductive layer 112 with a silicon oxide film or a silicon nitride film. The lower insulating film 114 is selectively etched to form a source contact hole 116. [ The lower insulating film 114 can be either wet or dry etched. Aluminum (Al) or an aluminum alloy (AlNd) is deposited and patterned as a first metal on the lower insulating film 114 including the source contact hole 116 to form the data line 118 and the source electrode 120 And a drain electrode 122 are formed. Here, the transparent conductive layer 112 and the source electrode 120 are electrically connected through the source contact hole 116.

The first amorphous silicon layer is formed on the lower insulating film 114 including the source electrode 120 and the drain electrode 122 and the data line 118 and the impurity is doped as shown in FIG. The ohmic contact layer 124 remaining on the source electrode 120 and the drain electrode 122 is formed. A second amorphous silicon layer is formed on the lower insulating film 114 including the ohmic contact layer 124. [ The second amorphous silicon layer is an intrinsic semiconductor layer not doped with impurities. The second amorphous silicon layer is patterned to form an active layer 126 located on the source electrode 120 and the drain electrode 122. [ The active layer 126 and the ohmic contact layer 124 are referred to as a semiconductor layer 125. The active layer 126 between the source electrode 12 and the drain electrode 122 is a channel region 128.

Generally, the temperature at which the amorphous silicon layer is formed is at least 300 degrees. When a soda lime glass is used as the lower substrate 110, the transparent conductive film 112 formed of a zinc oxide layer is formed by a process in which a sodium ion (Na +), a potassium Ions (K +), and magnesium ions (Mg < + >) from being diffused into the semiconductor layer 140. Since the zinc oxide layer 112 has a high-density film quality characteristic, alkali ions prevent diffusion.

An insulating material is deposited on the lower insulating film 114 including the active layer 126 and patterned to form the gate insulating film 130 on the active layer 126. [ The gate insulating film 130 uses a silicon oxide film or a silicon nitride film. Aluminum (Al) or an aluminum alloy (AlNd) is deposited and patterned as a second metal on the lower insulating film 114 including the gate insulating film 130 to form gate wirings And a gate electrode 132 connected to the gate wiring. The gate electrode 132 is located on the gate lower insulating film 114 corresponding to the channel region 128. The semiconductor layer 125 on the insulating film 114 including the source electrode 120 and the drain electrode 122, the source electrode 120 and the drain electrode 122 on the insulating film 112, A thin film transistor including a gate insulating film 130 on the gate insulating film 125 and a gate electrode 132 on the gate insulating film 130 corresponding to the channel region 128 is formed.

3E, a silicon oxide film or a silicon nitride film is deposited as an insulating material on the insulating film 130 including the gate electrode 132 to selectively remove an insulating material on the pixel region P to protect the thin film transistor Layer 134 is formed. The transparent conductive film 112 of the boundary region (not shown) separating the pixel regions P is selectively etched to form the pixel electrodes 136. [ The pixel electrode 136 should be formed independently of the adjacent pixel electrode 136.

If the zinc oxide film is not formed in the transparent conductive film 112, the alkali ions of the sodalime glass diffuse into the semiconductor layer 125, particularly, the channel region 128. Alkali ions diffused into the channel region 128 may change the semiconductor property of the channel region 128 to the conductive nature so that even when no voltage is applied to the gate electrode 132, The source electrode 120 and the drain electrode 122 are energized to increase the leakage current.

The manufacturing process of the upper substrate on which the color filter is formed is as follows. 4A, a soda lime glass having an Na ₂ O content of 1 wt% or more is prepared as an upper substrate 140, and a black matrix 142 for preventing light leakage is formed on the upper substrate 140 . The black matrix is formed by depositing chromium (Cr) / chromium oxide (CrOx) or resin on the entire surface and then patterning.

4B, a red color resist is formed on the upper substrate 140 including the black matrix 142 by a spin coating method, a red color pattern 144 is formed by a proximity exposure method, , A green color pattern 146 and a blue color pattern (not shown) are formed in the same manner as the red color pattern 144. [ The red, green, and blue color resists have the characteristics of a negative photosensitive film, so that the exposed portion remains, and the unexposed portion is removed.

As an anti-leaching layer 148 for preventing the leaching of alkali metal ions from soda lime glass on the upper substrate 140 including the color patterns 144 and 146 and the black matrix 142 as shown in FIG. 4C A zinc oxide layer is formed. The method of forming the zinc oxide layer is the same as that of the zinc oxide layer used as the transparent conductive layer 112. A silicon oxide film or a silicon nitride film is formed as an upper insulating film 150 on the leaching prevention film 148. A common electrode 152 is formed on the upper insulating film 150 so as to face the pixel electrode 138 of the array substrate to generate an electric field. The common electrode 152 forms an indium-tin-oxime (ITO) or indium-zinc-oxide (IZO) film as a conductive transparent material on the entire surface of the upper insulating film 150.

The reason why the upper insulating layer 150 is formed between the common electrode 150 and the leaching prevention layer 148 is that the zinc oxide layer used as the leaching prevention layer 148 is transparent and conductive, So that the common electrode 152 is not affected by the characteristics. The thickness of the upper insulating film 148 is about 1000 ANGSTROM. However, in the above-described upper substrate 140, the temperature of the manufacturing process progresses below 300 ° C., and alkali ions such as sodium ion (Na +), potassium ion (K +), and magnesium ion (Mg +) of soda lime glass If the soda lime glass is used as the upper substrate 140, the formation of the leaching prevention film 148 may be omitted. In addition, since the common electrode 150 is formed over the entire surface of the upper substrate 140, the upper insulating film 150 may not be formed unless it is affected by the conductivity of the leaching prevention film 148.

A seal pattern may be formed on any one of the lower substrate 110 and the upper substrate 140 and the lower substrate 110 and the upper substrate 140 may be integrally formed with each other. 110 and a color filter substrate as a common electrode of the upper substrate 140 facing each other and filling the space between the lower substrate 110 and the upper substrate 140 with liquid crystal to complete a liquid crystal display device.

In the above description, the transparent conductive layer and the leach prevention layer are typically used in a liquid crystal display device in which a zinc oxide layer is formed. However, the present invention can be applied to all flat panel display devices using a high temperature process. The present invention is not limited to the example, and various changes and modifications are possible.

1 is a schematic view of a conventional liquid crystal display

2 is a cross-sectional view of an array substrate according to the related art

Figs. 3A to 3E are cross-sectional views showing a process sequence of an array substrate of a liquid crystal display device according to the present invention

4A to 4C are cross-sectional views showing a process sequence of the color filter substrate of the liquid crystal display device according to the present invention

Claims (19)

delete delete delete delete delete delete delete delete delete delete delete delete delete Forming a first transparent conductive layer on a first substrate including an alkali ion and doping boron or aluminum as an impurity into the first transparent conductive layer; Forming a first insulating layer including a source contact hole on the first transparent conductive layer; A source electrode electrically connected to the first transparent conductive layer through the source contact hole on the first insulating layer, and a drain electrode spaced from the source electrode; Forming an ohmic contact layer on the source electrode and the drain electrode; Forming an active layer on the ohmic contact layer; Forming a gate insulating film on the active layer; Forming a gate electrode on the gate insulating film; Forming a protective layer on the gate electrode; Forming a pixel electrode by selectively patterning the first insulating layer and the first transparent conductive layer; And the second electrode is electrically connected to the second electrode. 15. The method of claim 14, Forming a black matrix, a color pattern, and a common electrode on the second substrate; Attaching the first and second substrates together; Filling the liquid crystal between the first and second substrates The method comprising the steps of: Claim 16 has been abandoned due to the setting registration fee. 16. The method of claim 15, And forming the black matrix, the color pattern, and the common electrode on the second substrate, Forming the black matrix on the second substrate including alkali ions; Forming the color pattern on the black matrix; Forming a second transparent conductive layer on the color pattern; Forming the common electrode on the second transparent conductive layer And the second electrode is electrically connected to the second electrode. Claim 17 has been abandoned due to the setting registration fee. 17. The method of claim 16, Wherein the forming of the black matrix, the color pattern, and the common electrode on the second substrate further comprises forming a second insulating film between the second transparent conductive layer and the common electrode Gt; Claim 18 has been abandoned due to the setting registration fee. 17. The method of claim 16, Wherein the first and second transparent conductive layers are zinc oxide layers formed by reaction of diethylzinc or dimethylzinc with a reactant including oxygen as a source material. 15. The method of claim 14, Wherein B ₂ H ₃ is used as the doping source of boron and trimethylaluminum (TMA) (Al (CH ₃ ) ₃ ) is used as the source of aluminum.

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