KR20010010115A - Liquid crystal display - Google Patents

Abstract

PURPOSE: A liquid crystal display is provided to make a slimness of a thickness of an upper substrate by forming a color filter on a lower substrate in which a thin film transistor is formed. CONSTITUTION: The liquid crystal display comprises a thin film transistor which is formed over a lower glass substrate(20). The thin film transistor has gate lines(32), a gate insulating film(40), a semiconductor layer(50), and data lines. Resistive contact layers(51,52) are formed at a plane where the source and drain electrodes(62,63) is contact with the semiconductor layer(50). An organic insulating film(70) having a contact hole(71) is formed over the thin film transistor. An RGB color filter(90) is formed over a reflection film(80) that is formed on the organic insulating film(70).

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

The present invention relates to a liquid crystal display device, and more particularly, to a thin film transistor (TFT) liquid crystal display device to which a reflective mode is applied.

In general, a liquid crystal display device injects a liquid crystal material between an upper substrate on which a common electrode and a color filter are formed, and a lower substrate on which a thin film transistor and a pixel electrode are formed, and applies different potentials to the pixel electrode and the common electrode. By changing the arrangement of the liquid crystal molecules to control the light transmittance of the device to represent the image.

Currently, the market trend of thin film transistor liquid crystal display-related products is expanding not only for notebooks, but also for large monitors and small and medium-sized products, and for small and medium-sized products, mainly hand-hold PC, PDA, and View CAM. Applies to the application. In particular, small information devices such as PDAs and hand-held PCs show low power consumption by applying a reflective mode without backlight in connection with battery capacity problems.

Next, a structure of a thin film transistor liquid crystal display device to which the conventional reflective mode is applied will be described with reference to FIG. 1.

The thin film transistor layer including the gate wiring (not shown), the gate insulating film 3, the semiconductor layer 4, and the data wiring (not shown) is formed on the glass substrate 1 of the lower substrate.

When the structure of the thin film transistor layer is described in detail, a gate line (not shown) formed of a metal or a conductor on the glass substrate 1 and serving as a scan signal line is connected to an end of the gate line to receive a scan signal from the outside. A gate wiring (not shown) to be transferred to the gate line and a gate wiring composed of the gate electrode 2 of the thin film transistor which is part of the gate line are formed. A gate insulating film 3 is formed on the entire upper surface of the glass substrate 1 on which the gate wiring is formed, and hydrogenated amorphous silicon is formed on the gate insulating film 3 overlapping with the gate electrode 2 of the gate wiring. The semiconductor layer 4 which consists of (alpha) -Si: H) is formed. In addition, a data line (not shown) formed of a metal or a conductor and connected to an end of the data line and formed of a metal or a conductor on the gate insulating layer 3 including the semiconductor layer 4 receives an image signal from the outside and receives data. A data pad (not shown) for transferring to a line, a source electrode 7 of a thin film transistor overlapping a portion of the gate electrode 2 on the semiconductor layer 4 by branching of the data line, and separated from the data line, A data line formed of a drain electrode 8 positioned on the opposite side to 7) and overlapping a part of the gate electrode 2 on the semiconductor layer 4 is formed. In addition, ohmic contacts made of amorphous silicon or the like doped with n-type impurities such as phosphorus (P) at high concentrations on the surfaces where the source electrode 7, the drain electrode 8, and the semiconductor layer 4 are in contact with each other. layers (5, 6) are formed.

An insulating film 9 having a contact hole 10 for exposing a part of the drain electrode 8 is formed on the thin film transistor layer including the gate wiring, the gate insulating film 3, the semiconductor layer 4, and the data wiring. The reflective film 11 connected to the drain electrode 8 through the contact hole 10 is formed in the pixel on the insulating film 9 by overlapping the gate line of the gate wiring with a predetermined region. In this case, the reflective film 11 is formed in each region defined by the intersection of the gate line and the data line to function as a pixel electrode.

In addition, R (red), G (green), and B (blue) color filters 13 are formed on the opposite surface of the glass substrate 12 of the upper substrate coupled to the lower substrate, and the color filter 13 The common electrode 14 formed of a transparent conductive material such as indium tin oxide (ITO) is formed on the upper portion.

The liquid crystal 15 is injected between the upper substrate and the lower substrate, and a diffuser, a retardation plate 16 and a polarizer 17 are formed on the glass substrate 12 of the upper substrate.

In a portable device using such a reflective thin film transistor liquid crystal display device, a requirement for low power consumption is as portable as possible, which is based on light weight of a product. Omitting the backlight in the reflective mode contributes to the weight reduction of the product, but there is a limit to the weight of the panel itself, which is closely related to the thickness of the glass substrate used to manufacture the panel. That is, the durability problem of glass substrates that can withstand the process of manufacturing a general thin film transistor liquid crystal display and transport inside and outside the facility has been minimized to a minimum thickness of 0.7 mm for large panels and 0.63 mm for small panels. Minimize to level. In order to improve the competitiveness of portable small and medium-sized products, it is necessary to develop ultra-light and ultra-slim products, and the optimum product depends on the ultra-light panel applying the reflective mode.

However, as shown in FIG. 1, the structure for forming the RGB color filter on the upper substrate has a limit in reducing the thickness of the glass substrate of the upper substrate, and thus, the panel weight is limited.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object thereof is to provide a liquid crystal display device and a method of manufacturing the same, which can reduce the thickness of an upper substrate in order to enhance product competitiveness of a thin film transistor liquid crystal display device.

1 is a cross-sectional view schematically showing a conventional reflective thin film transistor liquid crystal display device;

2A is a layout view schematically illustrating a lower substrate of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2B is a schematic cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention including a lower substrate along a line IIb-IIb ′ of FIG. 2A.

3A to 6A are layout views schematically illustrating a process of manufacturing a lower substrate of a liquid crystal display according to an exemplary embodiment of the present invention.

3B to 6B are cross-sectional views taken along lines IIIb-IIIb ', IVb-IVb', Vb-Vb ', and VIb-VIb' in FIGS. 3A to 6A, respectively.

In order to achieve the above object, the present invention is characterized in that the color filter is formed on the lower substrate, and the upper substrate is formed of only a glass substrate coated with a transparent electrode.

That is, a gate line formed on a lower glass substrate, a data line defining a pixel by crossing the gate line, a gate electrode formed at a portion where the gate line and the data line intersect, and a branch or part of a semiconductor layer and the gate line; A thin film transistor including a source electrode which is a branch or part of the data line, and a drain electrode facing the source electrode with respect to the gate electrode, an organic insulating layer having a contact hole formed on the thin film transistor and exposing the drain electrode; An opposing surface of an upper glass substrate formed on an organic insulating layer and connected to the drain electrode to form a lower substrate including a reflective film formed on the pixel and a color filter formed on the reflective film, and facing the lower substrate. The common electrode formed on the In addition, to form an upper substrate.

The protective film may further include a protective insulating film under the organic insulating film.

It is preferable to further include a black matrix formed on the upper glass substrate and having an opening formed in the pixel.

It is preferable to further include a diffusion plate formed on the reflective film, or to form the organic insulating film in a lens structure.

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

FIG. 2A is a layout view schematically illustrating a lower substrate of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2B is a schematic view illustrating a lower substrate along a line IIb-IIb ′ of FIG. 2A. It is sectional drawing which shows schematically a liquid crystal display device.

A thin film transistor layer including a gate wiring 30, 31, 32, a gate insulating film 40, a semiconductor layer 50, and data wirings 60, 61, 62, and 63 is formed on the lower glass substrate 20. have.

In detail, the structure of the thin film transistor layer may include aluminum (Al) or an aluminum alloy, molybdenum (Mo) or molybdenum alloy, aluminum-neodynium (Nd), chromium (Cr), and tantalum (Ta) on the lower glass substrate 20. A gate pad 31 formed of a metal or a conductor such as) and connected to a gate line 30 serving as a scan signal line and an end of the gate line 30 to receive a scan signal from the outside and transfer the scan signal to the gate line 30. ), The gate wirings 30, 31, and 32 formed of the gate electrode 32 of the thin film transistor which is a part of the gate line 30 are formed. In this case, the gate lines 30, 31, and 32 may be formed in a single layer or a double layer or more.

A gate insulating film 40 made of silicon nitride (SiN _X ) or the like is formed on the entire upper surface of the lower glass substrate 10 on which the gate wirings 30, 31, and 32 are formed, and the gates of the gate wirings 30, 31, and 32 are formed. A semiconductor layer 50 made of hydrogenated amorphous silicon is formed on the gate insulating layer 40 overlapping with the electrode 32.

The data line 60 is formed on the gate insulating layer 40 by a metal or conductor such as chromium, and is connected to the data line 60 and the end of the data line 60 serving as an image signal line, and receives an image signal from the outside. The data pad 61 and the data line 60 which are transferred to the semiconductor layer 50 are separated from the source electrode 62 and the data line 60 of the thin film transistor overlapping a part of the gate electrode 32 on the semiconductor layer 50. And a data line 60, 61, which is disposed on the opposite side of the source electrode 62 with respect to the gate electrode 32 and consists of a drain electrode 63 overlapping a part of the gate electrode 32 on the semiconductor layer 50. 62, 63) are formed.

Resistive contact layers 51 and 52 made of amorphous silicon or the like doped with high concentration of n-type impurities such as phosphorus are formed on surfaces where the source electrode 62 and the drain electrode 63 and the semiconductor layer 50 are in contact with each other. It is.

The thin film transistor layer is formed on the lower glass substrate 20 in the order of the gate wirings 30, 31, 32, the gate insulating film 40, the semiconductor layer 50, and the data wirings 60, 61, 62, and 63. Formed by an inverted staggered type thin film transistor, but in contrast, a staggered thin film transistor having a structure consisting of a data wiring, a semiconductor layer, a gate insulating film, and a gate wiring sequence, a semiconductor layer, a data wiring, and a gate wiring sequence It can be formed in a variety of structures, such as planar type thin film transistor by a structure consisting of.

A portion of the drain electrode 63 is exposed on the thin film transistor layer including the gate wirings 30, 31, 32, the gate insulating film 40, the semiconductor layer 50, and the data wirings 60, 61, 62, and 63. An organic insulating film 70 having a contact hole 71 is formed, and a protective film made of an insulating film such as silicon nitride may be formed under the organic insulating film 70 to prevent the thin film transistor channel portion of the thin film transistor layer from being contaminated. have.

The pixel on the organic insulating layer 70 overlaps with the gate line 30 of the gate wirings 30, 31, and 32, and is connected to the drain electrode 63 through the contact hole 71 of the organic insulating layer 70. The reflective film 80 is formed. In this case, the diffuser plate may be formed on the reflective layer 80, or the organic insulating layer 70 may be formed in a lens structure without forming the diffuser plate to enlarge the viewing angle of the user through scattering of light. An RGB color filter 90 is formed on the reflective film 80.

In addition, a common electrode 110 formed of a transparent conductive material such as ITO is formed on an opposite surface of the upper glass substrate 100 coupled to the lower glass substrate 20, and the opening is formed in the pixel on the glass substrate 100. A black matrix having a may be formed.

In addition, the liquid crystal 120 is injected between the upper and lower glass substrates 20 and 100, and the retardation plate 130 and the polarizer 140 are formed on the upper glass substrate 100. In this case, a diffusion plate may be formed on the glass substrate 100 to extend the viewing angle of the user through scattering of light.

As such, by changing the color filter formed on the upper substrate to the structure formed on the lower substrate, the thickness of the glass substrate of the upper substrate can be reduced, thereby making it possible to manufacture an ultralight panel.

Next, a method of manufacturing a liquid crystal display device having such a structure will be described in detail with reference to FIGS. 3A to 6A and FIGS. 3B to 6B.

3A through 6A are layout views schematically illustrating a process of manufacturing a lower substrate of a liquid crystal display according to an exemplary embodiment of the present invention, and FIGS. 3B through 6B are IIIb-IIIb 'and IVb- in FIGS. 3A through 6A, respectively. It is sectional drawing about lines IVb ', Vb-Vb', and VIb-VIb '.

First, as shown in FIGS. 3A and 3B, a sputtering method of a metal or a conductor such as aluminum or an aluminum alloy, molybdenum-tungsten alloy, aluminum-neodynium, chromium, and tantalum on the lower glass substrate 20 is performed. Deposited by a photolithography method and the like, and patterned by a photolithography method, formed on the ends of the gate line 30 and the gate line 30 extending horizontally on the lower glass substrate 20 and serving as scan signal lines. Gate wirings 30, 31, and 32 formed of a gate pad 31 for receiving a scan signal from the gate line 30 and transmitting the gate signal 30 to the gate line 30 and a gate electrode 30 of the thin film transistor that is part of the gate line 30 are formed. . In this case, the gate wirings 30, 31, and 32 may be formed in a single layer or a double layer or more.

Next, as illustrated in FIGS. 4A and 4B, silicon nitride or the like is chemically deposited on the entire lower glass substrate 20 on which the gate wirings 30, 31, and 32 are formed. 40). In addition, the upper surface of the gate insulating layer 40 is formed of a semiconductor such as hydrogenated amorphous silicon, which is plasma enhanced chemical vapor deposition (PE-CVD) using SiH ₄ , NH ₃ , N ₂ , and H ₂ mixed gases. An ohmic contact layer such as amorphous silicon doped with a high concentration of n-type impurities such as phosphorus in order to form the semiconductor layer 50 and reduce contact resistance with the metal film to be formed in a subsequent process on the semiconductor layer 50 ( 51, 52). Subsequently, the semiconductor layer 50 and the ohmic contact layers 51 and 52 on the gate insulating layer 40 are patterned by photolithography or the like so as to overlap only the upper portion of the gate electrode 32.

5A and 5B, a metal or conductive material such as chromium and molybdenum is deposited and patterned on the entire upper surface of the gate insulating film 40 to form a vertical line and serve as an image signal line 60. ) And a semiconductor pad 50 patterned by branching of the data pad 61 and the data line 60 which are connected to the ends of the data line 60 and receive image signals from the outside and transmit them to the data line 60. It is separated from the source electrode 62 and the data line 60 of the thin film transistor overlapping a part of the gate electrode 32 on the ohmic contact layers 51 and 52 and the source electrode 62 with respect to the gate electrode 32. The data wires 60, 61, 62, and 63 are formed on the opposite side to each other and include the drain electrode 63 overlapping the semiconductor layer 50 and the ohmic contact layers 51 and 52. In this case, the data lines 60, 61, 62, and 63 may be formed in a single layer or a double layer or more. Subsequently, the resistive contact layer exposed between the source electrode 62 and the drain electrode 63 is etched to expose the semiconductor layer 50 so that the gate wirings 30, 31, 32, the gate insulating film 40, and the semiconductor layer ( 50, the thin film transistor layer including the data lines 60, 61, 62, and 63 is completed.

In this case, the gate wirings 30, 31, and 32, the gate insulating film 40, the semiconductor layer 50, and the data wirings are disposed on the lower glass substrate 20 through the processes of FIGS. 3A to 5A and 3B to 5B. 60, 61, 62, and 63) in order to form an inverted staggered thin film transistor, but alternatively, a data line including a source / drain electrode on a lower glass substrate, a semiconductor layer, a gate insulating film, and a gate electrode Forming a staggered thin film transistor by forming a gate wiring sequence or forming a planar thin film transistor by forming a semiconductor layer, a data wiring including a source / drain electrode, and a gate wiring including a gate electrode in an upper portion of a lower glass substrate. It is also possible to form thin film transistors having various structures.

6A and 6B, a thin film including the gate wirings 30, 31, and 32, the gate insulating film 40, the semiconductor layer 50, and the data wirings 60, 61, 62, and 63. The organic insulating layer 70 is deposited on the entire upper surface of the transistor layer by spin coating or the like, and the contact hole 71 is formed to expose a part of the drain electrode 63 of the thin film transistor by a method such as photolithography. do. At the same time, a contact hole 72 is formed to expose a portion of the gate pad 31 and the data pad 61.

In this case, in order to prevent the thin film transistor channel portion of the thin film transistor layer from being contaminated, a protective insulating film may be formed under the organic insulating film 70 by a sputtering method or the like.

Next, as shown in FIGS. 2A and 2B, a reflective film 80 to be used as a pixel electrode is deposited on the entire upper surface of the organic insulating film 70, and is defined as an area where the gate line 30 and the data line 60 cross each other. Patterning so as to form each pixel electrode connected to the drain electrode 63 through the contact hole (71). At this time, the patterned reflective film 80 allows a portion to overlap the gate line 30 to obtain a sufficient holding capacity. In addition, it is preferable to form a diffusion plate on the reflective film 80 to extend the viewing angle of the user through scattering of light. However, when the diffusion plate is not formed on the reflective film 80, the organic insulating film 70 under the reflective film 80 may be formed in a lens structure to extend the viewing angle of the user through light scattering. Thereafter, the lower substrate is completed by forming the RGB color filter 90 on the reflective film 80.

Next, the upper substrate is completed by sputtering deposition of a transparent conductive material such as ITO on the upper glass substrate 100 to form the common electrode 110. In this case, a black matrix having an opening in the pixel may be formed in the upper glass substrate 100.

In the manufacturing method according to the embodiment of the present invention, unlike the prior art by forming a color filter on the lower substrate, and by using the upper glass substrate coated with a common electrode such as ITO as the upper substrate conventional thickness of the upper glass substrate 100 Compared to the 0.3t level, the weight reduction of the product equipped with the liquid crystal display device can be realized.

Next, after combining the upper substrate and the lower substrate such that the common electrode 110 of the upper glass substrate 100 and the color filter 90 of the lower glass substrate 20 face each other, the upper glass substrate 100 and the lower glass substrate are combined. The liquid crystal 120 is injected and sealed between 20. The reflective thin film transistor liquid crystal display device is completed by forming the phase difference plate 130 and the polarizing plate 140 on the upper glass substrate 100 combined with the lower glass substrate 20.

As described above, the present invention can form an upper substrate using only a glass substrate coated with a transparent electrode by forming a color filter on a lower glass substrate on which a thin film transistor is formed. As a result, it is possible to improve the competitiveness of a portable small and medium product equipped with a liquid crystal display.

Claims (5)

A gate line formed on a lower glass substrate, a data line defining a pixel by crossing the gate line, a gate electrode formed at a portion where the gate line and the data line intersect, and a branch or part of a semiconductor layer and the gate line, and the data A thin film transistor including a source electrode which is a branch or part of a line, and a drain electrode facing the source electrode around the gate electrode, an organic insulating film having a contact hole formed on the thin film transistor and exposing the drain electrode, the organic insulating film A lower substrate formed on the upper side and connected to the drain electrode, the lower substrate including a reflective film formed on the pixel and a color filter formed on the reflective film; An upper substrate including a common electrode formed on an opposite surface of the upper glass substrate facing the lower substrate; Liquid crystal display comprising a. The liquid crystal display of claim 1, further comprising a protective insulating layer under the organic insulating layer to cover the thin film transistor. The liquid crystal display device of claim 1, further comprising a black matrix formed on the upper glass substrate and having an opening formed in the pixel. The liquid crystal display device according to any one of claims 1 to 3, further comprising a diffusion plate formed on the reflective film. The liquid crystal display device according to any one of claims 1 to 3, wherein the organic insulating film has a lens structure.