KR20080069798A - Liquid crystal display - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to suppress the leakage current due to light by forming a channel light-shielding layer such that the channel light-shielding layer overlaps a semiconductor layer and to improve the recycling efficiency of light by forming black matrix as reflective conductive material. A first light-absorbing film(22) is formed on a first insulating substrate(10). A gate line is formed on the first light-absorbing film. As above, the first light-absorbing film is disposed between the gate line and the first insulating substrate. The first light-absorbing film prevents an external environment light from being reflected on an LCD, thereby suppressing the decrease of contrast ratio of the LCD. A semiconductor layer(40) is formed on the gate line. A data line is formed on the semiconductor layer. The data line crosses the gate line while the data line is insulated from the gate line. A channel light-shielding layer(70) is formed on the data line while overlapping the semiconductor layer.

Description

Liquid crystal display

1 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

3 is a cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

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

1: light 10: first insulating substrate

22: first light absorption film 26: gate electrode

30: gate insulating film 40: semiconductor layer

55, 56: ohmic contact layer 60: second light absorbing layer

65 source electrode 66 drain electrode

70: channel shading 72: protective film

80: pixel electrode 100: liquid crystal display device

102: upper display panel 103: lower display panel

104: liquid crystal layer 110: second insulating substrate

120: black matrix 130: color filter

140: overcoat layer 150: common electrode

200: liquid crystal display 270: channel light shielding film

300: liquid crystal display 310: column spacer

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of suppressing light leakage current.

Liquid crystal display is one of the most widely used flat panel displays. It consists of two substrates on which electrodes are formed and a liquid crystal layer interposed therebetween. The display device is applied to rearrange the liquid crystal molecules of the liquid crystal layer to control the amount of light transmitted.

Among the liquid crystal display devices, a field generating electrode is provided on each of two display panels. Among them, a plurality of pixel electrodes are arranged in a matrix form on the lower panel, and one common electrode covers the entire surface on the upper panel. In such a liquid crystal display, an image is displayed by applying a separate voltage to each pixel electrode. To this end, a thin film transistor, which is a three-terminal element for switching a voltage applied to a pixel electrode, is connected to each pixel electrode, and a gate line for transmitting a signal for controlling the thin film transistor and a data line for transmitting a voltage to be applied to the pixel electrode are provided. A plurality of wirings are formed on the substrate.

The liquid crystal display is a passive light emitting device that provides light from the backlight unit under the lower panel. When such light hits the semiconductor layer constituting the thin film transistor, there is a problem that a light leakage current is generated between the source electrode and the drain electrode.

An object of the present invention is to provide a liquid crystal display device capable of suppressing light leakage current.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, a liquid crystal display device includes a first insulating substrate, a first light absorption film formed on the first insulating substrate, and a first light absorption film formed on the first insulating substrate. A gate wiring, a semiconductor layer formed on the gate wiring, a data wiring formed on the semiconductor layer and insulated from and intersecting the gate wiring, and a channel light blocking film formed on the data wiring and overlapping the semiconductor layer. do.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

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

1 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display device 100 according to an exemplary embodiment of the present invention may include an upper display panel 102 on which a thin film transistor array is formed, a lower display panel 103 and an upper display panel disposed to face the upper display panel 102. The liquid crystal layer 104 is interposed between the 102 and the lower panel 103. The light 1 input from a backlight unit (not shown) positioned below the lower panel 103 is transmitted to the viewer via the lower panel 103 and the upper panel 102 in sequence.

Hereinafter, the upper panel 102 will be described first.

The upper panel 102 includes a first insulating substrate 10 and a thin film transistor (TFT) 45 that is a switching element formed on the first insulating substrate 10. The thin film transistor 45 includes a gate electrode 26, a gate insulating film 30, a semiconductor layer 40, ohmic contact layers 55 and 56, a source electrode 65, and a drain electrode 66.

The first insulating substrate 10 is made of a non-conductive material, for example, a material such as glass or ceramic.

The gate electrode 26 is formed by branching from a gate line (not shown) extending in the first direction on the first insulating substrate 10. Hereinafter, the gate electrode 26 and the gate line are called gate wirings.

A first light absorption film 22 aligned with the gate wiring is formed under the gate wiring, that is, between the gate wiring and the first insulating substrate 10. The first light absorption layer 22 prevents the external environment light from being reflected by the liquid crystal display 100. In the liquid crystal display device 100 of the present exemplary embodiment, since the gate electrode 26 is disposed adjacent to the viewer, the first light absorption film 22 is not between the gate electrode 26 and the first insulating substrate 10. Light is reflected from the gate electrode 26 to lower the contrast ratio. Therefore, the first light absorption layer 22 may prevent the external environment light from being reflected by the liquid crystal display 100, thereby preventing the contrast ratio from dropping. The first light absorption film 22 may be formed of, for example, an oxide or a nitride. In detail, the first light absorption layer 22 may be formed of an oxide or a nitride of a material forming the gate electrode 26.

The gate wiring is preferably formed in alignment with the first light absorption film 22. The gate electrode 26 is made of aluminum-based metals such as aluminum (Al) and aluminum alloys, silver-based metals such as silver (Ag) and silver alloys, copper-based metals such as copper (Cu) and copper alloys, molybdenum (Mo) and A molybdenum-based metal such as molybdenum alloy, chromium (Cr), titanium (Ti), tantalum (Ta) and the like can be made. In addition, the gate electrode 26 may have a multi-layer structure including two conductive layers (not shown) having different physical properties. One of the conductive films is made of a low resistivity metal such as an aluminum-based metal, a silver-based metal, or a copper-based metal so as to reduce the signal delay or voltage drop of the gate electrode 26. In contrast, the other conductive layer is made of a material having excellent contact properties with other materials, particularly indium tin oxide (ITO) and indium zinc oxide (IZO), such as molybdenum-based metals, chromium, titanium, tantalum and the like. A good example of such a combination is a chromium bottom film and an aluminum top film and an aluminum bottom film and a molybdenum top film. However, the present invention is not limited thereto, and the gate electrode 26 may be made of various various metals and conductors.

For example, when the gate wiring is made of Mo / AlNd, the first light absorption film 22 may be made of MoOx, MoNx, AlNdOx, or AlNdNx.

A gate insulating layer 30 made of silicon nitride (SiNx) or the like is formed on an entire surface of the first insulating substrate 10 on which the gate electrode 26 is formed.

The semiconductor layer 40 made of a semiconductor such as hydrogenated amorphous silicon or polycrystalline silicon is formed in an island shape on the gate insulating layer 30 so as to overlap the gate electrode 26. The ohmic contact layers 55 and 56 made of a material such as silicide or n + hydrogenated amorphous silicon doped with high concentration of n-type impurities are formed on the upper portion.

Data wires 65 and 66 are formed on the ohmic contact layers 55 and 56 and the gate insulating film 30. The data wires 65 and 66 are formed in a vertical direction and intersect the gate line 22 to define a pixel, and branch from the data line to a branch shape to the upper portion of the ohmic contact layer 55. It is separated from the extended source electrode 65 and the source electrode 65, and is formed on the ohmic contact layer 56 to face the source electrode 65 around the channel portion of the gate electrode 26 or the thin film transistor. And a drain electrode 66.

A second light absorption film 60 aligned with the data wires 65 and 66 is formed under the data wires 65 and 66, that is, between the data wires 65 and 66 and the gate insulating film 30. The second light absorption layer 60 prevents the external environment light from being reflected by the liquid crystal display 100. In the liquid crystal display device 100 according to the present embodiment, since the data lines 65 and 66 are disposed adjacent to the viewer, the second light absorption film 60 is connected to the data lines 65 and 66 and the first insulating substrate 10. If not, light is reflected from the data lines 65 and 66, resulting in a low contrast ratio. Accordingly, the second light absorption layer 60 may prevent the external environment light from being reflected by the liquid crystal display 100, thereby preventing the contrast ratio from dropping. The second light absorption film 60 may be formed of, for example, oxide or nitride. In detail, the data line 65 may be formed of an oxide or a nitride of a material forming the data lines 65 and 66.

The data lines 65 and 66 are preferably formed in alignment with the second light absorption film 60. The data lines 65 and 66 are preferably made of refractory metals such as chromium, molybdenum-based metals, tantalum, and titanium, and include a lower layer (not shown) such as a refractory metal and an upper layer of low resistance material (not shown) thereon. It may have a multilayer film structure consisting of. Examples of the multilayer film structure include a triple film of molybdenum film, aluminum film, and molybdenum film in addition to the above-described double film of chromium lower film and aluminum upper film or aluminum lower film and molybdenum upper film.

For example, when the data lines 65 and 66 are made of MoNb / Al / MoNb, the second light absorption film 60 may be made of MoNbOx or MoNbNx.

The source electrode 65 overlaps at least a portion of the semiconductor layer 40, and the drain electrode 66 faces the source electrode 65 around the gate electrode 26 and at least partially overlaps the semiconductor layer 40. do. Here, the ohmic contact layers 55 and 56 exist between the semiconductor layer 40 below and the source electrode 65 and the drain electrode 66 above and serve to lower the contact resistance.

The channel light blocking film 70 is formed on the semiconductor layer 40 exposed by the data wires 65 and 66. The channel light blocking film 70 prevents light leakage current from being emitted by the light 1 from the backlight unit to the channel region of the semiconductor layer 40. For example, the channel light blocking film 70 may be formed of a metal (metal oxide) such as chromium or chromium oxide, or an organic black resist.

A protective film 72 is formed on the entire surface of the first insulating substrate 10 on which the data wirings 65 and 66 and the channel light blocking film 70 are formed. For example, the passivation layer 72 is formed of an inorganic material made of silicon nitride or silicon oxide, an organic material having excellent planarization characteristics and photosensitivity, or a plasma enhanced chemical vapor deposition (PECVD). Low dielectric constant insulating materials such as -Si: C: O and a-Si: O: F. In addition, the passivation layer 72 may have a double layer structure of a lower inorganic layer and an upper organic layer to protect the exposed semiconductor layer 44 while maintaining excellent characteristics of the organic layer. In addition, a color filter resin may be used as the passivation layer 72. In this case, the color filter 130 of the lower display panel 103 may be omitted.

In the passivation layer 72, a contact hole 74 exposing the drain electrode 66 is formed. The pixel electrode 82, which is electrically connected to the drain electrode 66 and positioned in the pixel, is formed on the passivation layer 72 through the contact hole 74. The pixel electrode 82 to which the data voltage is applied generates an electric field together with the common electrode 150 of the upper panel 102 so that the liquid crystal molecules of the liquid crystal layer 104 between the pixel electrode 82 and the common electrode 150 are formed. Determine the array. The pixel electrode 82 may be made of a transparent conductor such as ITO or IZO or a reflective conductor such as aluminum.

An alignment layer (not shown) may be coated on the pixel electrode 80 to align the liquid crystal molecules.

Next, the lower panel 103 will be described.

A black matrix 120 is formed on the second insulating substrate 110 made of a transparent insulating material such as glass to prevent light leakage and partition the pixel region. Since the recycling efficiency of the light 1 can be increased when the light 1 from the backlight unit is reflected back rather than absorbed by the black matrix 120, the black matrix 120 is made of a reflective conductor. desirable. For example, the black matrix 120 may be made of a metal (metal oxide) such as chromium or chromium oxide.

When the first light absorbing film 22, the second light absorbing film 60, and the channel difference light film 70 formed on the upper panel 102 can effectively partition the pixel areas to effectively prevent light leakage between the pixel areas. The black matrix 120 may be omitted.

In addition, red, green, and blue color filters 130 are sequentially arranged in the pixel region between the black matrices 120. As described above, when the color filter resin is used as the passivation layer 72, the color filter 130 of the lower display panel 103 may be omitted.

An overcoat layer 140 may be formed on the color filter 130 to planarize these steps.

The common electrode 150 made of a transparent conductive material such as ITO or IZO is formed on the overcoat layer 140 or the color filter 130. An anti-reflective film (not shown) may be coated on the common electrode 150 to align the liquid crystal molecules.

As such, when the upper display panel 102 and the lower display panel 103 are aligned and combined with each other, and the liquid crystal layer 104 is formed therebetween, the basic structure of the liquid crystal display device 100 is achieved.

Hereinafter, a liquid crystal display according to another exemplary embodiment of the present invention will be described with reference to FIG. 2. 2 is a cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention. For convenience of description, members having the same functions as the members shown in the drawings (FIG. 1) of the previous embodiment are denoted by the same reference numerals and description thereof will be omitted, and the following description will focus on differences.

In the liquid crystal display 200 of this embodiment, the channel light shielding film 270 is formed on the passivation film 72.

That is, the passivation layer 72 is formed on the data lines 65 and 66 and the semiconductor layer 40 exposed thereto, and the channel light blocking layer 270 is formed on the passivation layer 72 so as to overlap the semiconductor layer 40. . The channel light blocking film 270 serves to prevent light 1 from being emitted from the backlight unit 1 through the channel region of the semiconductor layer 40. For example, the channel light blocking film 270 may be made of a metal (metal oxide) such as chromium or chromium oxide, or an organic black resist.

When the first light absorbing film 22, the second light absorbing film 60, and the channel light blocking film 270 formed on the upper panel 202 can effectively partition pixel areas to effectively prevent light leakage between the pixel areas. The black matrix 120 may be omitted. When the color filter resin is used as the passivation layer 72, the color filter 130 of the lower display panel 103 may be omitted.

Hereinafter, a liquid crystal display according to another exemplary embodiment of the present invention will be described with reference to FIG. 3. 3 is a cross-sectional view of a liquid crystal display according to still another embodiment of the present invention. For convenience of description, members having the same functions as the members shown in the drawings (FIG. 2) of the previous embodiment are denoted by the same reference numerals and description thereof will be omitted, and the following description will focus on differences.

In the liquid crystal display device 300 according to the present exemplary embodiment, column spacers 310 aligned with the channel light blocking film 270 are formed on the channel light blocking film 270. The column spacer 310 maintains a cell gap between the upper panel 202 and the lower panel 103.

Since the channel light blocking film 270 may be formed using the same mask in the process of forming the column spacer 310, the manufacturing cost may be reduced because no additional photo process is required.

When the first light absorbing film 22, the second light absorbing film 60, and the channel light blocking film 270 formed on the upper panel 202 can effectively partition pixel areas to effectively prevent light leakage between the pixel areas. The black matrix 120 may be omitted. When the color filter resin is used as the passivation layer 72, the color filter 130 of the lower display panel 103 may be omitted.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

As described above, according to the liquid crystal display according to the present invention, the light leakage current can be suppressed by forming a thin film transistor on the upper display panel adjacent to the viewer and forming a channel light blocking film to overlap the semiconductor layer.

In addition, the contrast ratio may be increased by forming a light absorption film under the gate electrode, the source electrode, or the drain electrode. In addition, the recycling efficiency of light can be improved by forming a black matrix with a reflective conductor.

Claims (15)

A first insulating substrate; A first light absorption film formed on the first insulating substrate; A gate wiring formed on the first light absorption film; A semiconductor layer formed on the gate wiring; A data line formed on the semiconductor layer and insulated from and crossing the gate line; And And a channel light blocking film formed on the data line and overlapping the semiconductor layer. According to claim 1, And the channel light blocking film completely overlaps the semiconductor layer exposed by the data line. According to claim 1, The channel light blocking layer is formed of chromium, chromium oxide, chromium / chromium oxide, or organic black resist. According to claim 1, A protective film formed on the channel light blocking film and having contact holes formed therein; And And a pixel electrode formed on the passivation layer and connected to a portion of the data line through the contact hole. The method of claim 4, wherein The protective layer is a liquid crystal display device made of a color filter. According to claim 1, A passivation layer interposed between the data line and the channel light blocking layer and having a contact hole formed therein; And And a pixel electrode formed on the passivation layer and connected to a portion of the data line through the contact hole. The method of claim 6, The protective layer is a liquid crystal display device made of a color filter. The method of claim 6, A second insulating substrate facing the first insulating substrate; And And a column spacer formed on the channel light blocking layer in alignment with the channel light blocking film and maintaining a cell gap between the first and second insulating substrates. According to claim 1, The first light absorbing layer is formed of an oxide or nitride. The method of claim 9, The first light absorbing layer is formed of an oxide or nitride of a material forming the gate line. According to claim 1, And a second light absorption film interposed between the first insulating substrate and the data line and aligned with the data line. The method of claim 11, wherein The second light absorbing layer is formed of an oxide or nitride. The method of claim 12, The second light absorbing layer is formed of an oxide or nitride of a material forming the data line. According to claim 1, A second insulating substrate facing the first insulating substrate; And And a black matrix formed on the second insulating substrate and formed of a reflective conductor defining a pixel area. The method of claim 14, And the black matrix is formed of chromium, chromium oxide, or chromium / chromium oxide.

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