KR100620846B1 - Liquid Crystal Display Device and Method of Fabricating the Same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method of manufacturing the liquid crystal display device in which bonding properties between a semiconductor layer and a gate insulating layer made of an organic film are improved.

In the present invention, the gate insulating layer is formed using an organic material on the substrate on which the gate electrode is formed, and then the intermediate insulating layer is thinly formed of a mixed material in which organic and inorganic materials are mixed in a predetermined ratio on the gate insulating layer, An active layer of a thin film transistor is formed of a semiconductor material on the insulating layer.

According to the present invention, the bonding property between the semiconductor layer and the organic film is improved to prevent the phenomenon that the semiconductor layer floats on the insulating layer.

Description

Liquid crystal display device and method of manufacturing the same {Liquid Crystal Display Device and Method of Fabricating the Same}             

1 is a cross-sectional view showing a vertical cross-sectional structure of a thin film transistor section constituting a liquid crystal cell in a conventional liquid crystal display device.

2 is a cross-sectional view illustrating a vertical cross-sectional structure of a thin film transistor unit constituting a liquid crystal cell in a liquid crystal display device according to an exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

1,50: lower substrate 8,64: source electrode

10,52: gate electrode 12,66: drain electrode

14,72 pixel electrode 16,70 drain contact hole

30,54 gate insulating layer 32,58 semiconductor layer

34,60: ohmic contact layer 36,62: active layer

38,68: protective film 56: intermediate insulating layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly, to a liquid crystal display device and a method for manufacturing the same, in which a bonding property between a semiconductor layer and a gate insulating layer of an organic film is improved.

In general, a liquid crystal display device (LCD) displays an image corresponding to a data signal on a panel by adjusting the light transmittance of liquid crystal cells arranged in a matrix form on the liquid crystal panel as a video data signal supplied thereto. do. To this end, the liquid crystal display device includes a liquid crystal panel in which liquid crystal cells forming pixel units are arranged in an active matrix form, and a driver integrated circuit (hereinafter, referred to as "IC") for driving the liquid crystal cells. In the liquid crystal panel, the lower substrate is disposed in a direction in which data lines for transmitting data signals from the data driver IC to the liquid crystal cells and gate lines for transmitting scan signals from the gate driver IC to the liquid crystal cells are perpendicular to each other. Is formed on the phase. Liquid crystal cells are formed at each intersection of these data lines and gate lines. Each of the liquid crystal cells is provided with a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer. The pixel electrode is formed for each liquid crystal cell on the lower substrate, while the common electrode is integrally formed on the entire surface of the upper substrate. In addition, each liquid crystal cell is formed of a thin film transistor (hereinafter referred to as "TFT") used as a switch element. In liquid crystal cells in which a scan signal is supplied to the gate electrode of the TFT through the gate line, a conductive channel is formed between the source and drain electrodes of the TFT, and at this time, the data voltage supplied to the source electrode of the TFT via the data line is TFT. The light transmittance of the liquid crystal layer is adjusted by being supplied to the pixel electrode via the drain electrode of the liquid crystal layer.

1 is a cross-sectional view showing a vertical cross-sectional structure of a TFT constituting a liquid crystal cell. Referring to FIG. 1, first, a metal material (metal such as Mo, Al, Cr, etc.) is sputter deposited on the lower substrate 1, and then patterned by photo-etching to form a gate electrode of a TFT. (10) is formed. An insulating material is deposited on the lower substrate 1 on which the gate electrode 10 is formed to form a gate insulating layer 30. At this time, an inorganic material such as SiNx is mainly used as the insulating material. On the gate insulating layer 30, a semiconductor layer 32 made of amorphous silicon (Si) and an ohmic contact layer 34 made of n + amorphous silicon doped with phosphorus (P) are successively deposited. The semiconductor layer 32 and the ohmic contact layer 34 form an active layer 36. Metal materials such as Cr and Mo are deposited on the ohmic contact layer 34 and the gate insulating layer 30 and then patterned. The patterned metal material layer becomes a source electrode 8 and a drain electrode 12 of the TFT. The ohmic contact layer 34 exposed between the source electrode 8 and the drain electrode 12 is removed by an etching operation. Next, an insulating material passivation layer 38 is entirely formed on the gate insulating layer 30 including the exposed semiconductor layer 32 and the source and drain electrodes 8 and 12. Conventionally, an inorganic material, such as SiNx, has been deposited through a CVD (Chemical Vapor Deposition) method as a material of the protective film. However, recently, an organic material having a lower dielectric constant than the inorganic material is used as a method for increasing the opening ratio of the liquid crystal cell. Mainly used. The portion of the protective film 38 on the drain electrode 12 of the TFT is removed by the etching operation to form the drain contact hole 16. Subsequently, an indium tin oxide (ITO) material is deposited on the protective film 38 by sputtering and then patterned, thereby forming the pixel electrode 14. The pixel electrode 14 is connected to the drain electrode 12 through the drain contact hole 16.

As described above, after the gate electrode 10 is formed on the lower substrate 1, the gate insulating layer 30 is entirely formed on the lower substrate 1 using an insulating material. Conventionally, inorganic insulating materials such as SiNx have been mainly used as the material of the gate insulating layer 30. However, when the gate insulating layer 30 is formed of an inorganic film, since the thickness of the gate insulating layer 30 is formed to be uniform, the upper surface of the gate insulating layer 30 is not flat as shown in FIG. 1. The stepped portion is formed along the electrode pattern formed at the lower portion thereof. As a result, a stepped portion is formed in the active layer 36 and the source and drain electrodes 8 and 12 formed on the gate insulating layer 30. In particular, when the source electrode 8 and the drain electrode 12 are formed, In this stepped portion, disconnection failure occurs, or a defective problem such as short-circuit with the gate electrode 10 through the disconnected active layer 36 and the gate insulating layer 30 occurs. In order to solve this problem, a method of using an organic material as a material of the gate insulating layer 30 has recently emerged. Examples of the organic material used for the gate insulating layer 30 are BCB (Benzocyclobutene), SOG (Spin on Glass), Acryl and the like, which are formed on the substrate by a spin coating method or the like. . When the gate insulating layer 30 is formed of an organic layer by using a spin coating method or the like, the upper surface of the gate insulating layer 30 formed thereon is flat even though a stepped part such as an electrode pattern is present on the substrate. have. In addition, when the gate insulating layer 30 is formed of an inorganic film, a process is difficult and manufacturing cost is required because it is generally deposited in a vacuum state using a chemical vapor deposition ("CVD") equipment Although there is a disadvantage in increasing this, when the gate insulating layer 30 is formed of an organic film through a spin coating method or the like, the process time can be shortened, and a relatively simple manufacturing process and low cost can be manufactured. However, in the case of using the organic film as the gate insulating layer 30, another problem arises in that the bonding property with the semiconductor layer 32 formed thereon is inferior to that in the case of using the inorganic film. The semiconductor layer 32 formed on the gate insulating layer 30 to form the conductive channel of the TFT is made of an inorganic material of amorphous silicon. In general, the bonding property between the inorganic film and the organic film is not good. As a result, in a liquid crystal display device using an organic film as a material of the gate insulating layer 30, a poor bonding occurs between the organic gate insulating layer 30 and the inorganic semiconductor layer 32, and the inorganic semiconductor layer is formed on the gate insulating layer 30. There exists a disadvantage that interface characteristics fall, such as (32) lifting.

Accordingly, an object of the present invention is to provide a liquid crystal display device and a method for manufacturing the same, which improve the bonding property between a semiconductor layer and a gate insulating film made of an organic film.

In order to achieve the above object, the liquid crystal display device of the present invention is a gate insulating layer formed of an organic material flat on the substrate on which the gate electrode is formed, and a mixed material in which organic materials and inorganic materials are mixed in a predetermined ratio. And an intermediate insulating layer thinly formed on the substrate, and an active layer formed of a semiconductor material on the intermediate insulating layer.

A method of manufacturing a liquid crystal display device according to the present invention includes forming a gate insulating layer using an organic material on a substrate on which a gate electrode is formed, and a mixed material in which an organic material and an inorganic material are mixed in a predetermined ratio on the gate insulating layer. And forming a thin intermediate insulating layer, and forming an active layer constituting a thin film transistor of a liquid crystal cell with a semiconductor material on the intermediate insulating layer.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. 2.

2 is a cross-sectional view illustrating a cross-sectional structure of a TFT constituting a liquid crystal cell of a liquid crystal display device according to an exemplary embodiment of the present invention. Referring to FIG. 2, the liquid crystal display according to the exemplary embodiment of the present invention has a gate insulating layer 54 formed flat on the lower substrate 50 on which the gate electrode 52 is formed, and an inorganic material, and a predetermined ratio. An intermediate insulating layer 56 made of an organic material added to the gate insulating layer 54 and a semiconductor layer 58 and an ohmic contact layer 60 sequentially formed on the intermediate insulating layer 56. The active layer 62 of the formed TFT, the source electrode 64 and the drain electrode 66 of the TFT formed on the active layer 62, and the intermediate insulating layer 56 on which the TFT is formed are flat with an organic film. The formed protective film 68 and the pixel electrode 72 formed on the protective film 68 and connected to the drain electrode 66 of the TFT through the contact hole 70 are provided. In the liquid crystal display device according to the present invention, by using the organic film as the gate insulating layer 54, the upper surface of the gate insulating layer 54 can be formed flat as shown in FIG. The intermediate insulating layer 56 made of an organic material containing an inorganic material is formed between the organic gate insulating layer 54 and the semiconductor layer 58, thereby forming the gate insulating layer 54 and the semiconductor layer 58 made of an inorganic material. ) Improves the bonding properties between As the protective film 68 formed on the TFT and the intermediate insulating layer 56, an organic material having a relatively small dielectric constant is used to improve the opening ratio of the liquid crystal cell.

Step by step manufacturing method of the liquid crystal display device having such a cross-sectional structure is as follows. First, a metal material (metal such as Mo, Al, Cr, etc.) is deposited on the lower substrate 50 by a sputtering method, and then the TFT is formed through a patterning operation using a photo-etching method. The gate electrode 52 is formed. After the gate electrode 52 is formed, the gate insulating layer 54 is formed by forming an entire surface of the organic material on the lower substrate 50 using a spin coating method or the like. At this time, a material having a relatively large dielectric constant value of about 3 to 4 is used as the organic material. Unlike the conventional method of forming the gate insulating layer with an inorganic material, the upper surface can be planarized by forming an organic film by a spin coating method or the like. In addition, since the use of vacuum deposition equipment such as CVD equipment is unnecessary, the process can be simplified, and manufacturing time and manufacturing cost can be reduced. Next, the intermediate insulating layer 56 is formed on the organic gate insulating layer 54. As the material of the intermediate insulating layer 56, an organic material (BCB, SOG, Acryl, etc.) containing at least 30% or more of inorganic materials such as Si, O, N, and F is used. Then, the material is selected so that the heat resistance temperature is 100 ° C. or more and the light transmittance is 80% or more, and the mixing ratio is adjusted. The method of forming the intermediate insulating layer 56 uses spin coating, rolling, dipping, and the like, without using vacuum equipment such as CVD equipment. Here, spin coating is a method of dropping a liquid insulating material on a rotating substrate to form a flat insulating film by centrifugal force, and rolling is a method of forming an insulating film by applying an insulating material to a roller and pushing a roller on the substrate. to be. In addition, dipping is a method of forming an insulating film on a substrate by dipping the substrate in a liquid liquid of an insulating material and then removing the substrate. Whichever method is used, the thickness of the intermediate insulating layer 56 is made thinner than 300 kPa. After forming the intermediate insulating layer 56, the semiconductor layer 58 made of amorphous silicon (Si) and the ohmic contact layer 60 made of n + amorphous silicon doped with phosphorus (P) are successively formed. By vapor deposition. The semiconductor layer 58 and the ohmic contact layer 60 form the active layer 62 of the TFT. When the semiconductor layer 58 and the ohmic contact layer 60 are formed, the gate insulating layer 54 and the intermediate insulating layer 56 may be flat, so that the gate insulating layer 54 and the ohmic contact layer 60 may be flat. As a result, failure problems such as disconnection of the source layer 64 and the drain electrode 66 and the gate electrode 52 formed on or over the active layer 62 are prevented. Meanwhile, in the present invention, the intermediate insulating layer 56 formed by mixing an organic material and an inorganic material is formed between the organic gate insulating layer 54 and the inorganic semiconductor layer 58, and thus the semiconductor layer 58, which is conventionally problematic, The problem of poor bonding between the organic gate insulating layers 54 is prevented. This is due to the improvement of the bonding property with the semiconductor layer 58, which is an inorganic film, because the intermediate insulating layer 56 containing an organic material as a main component has a certain inorganic material property. This prevents the semiconductor layer 58 from being lifted up on the insulating layer 56. On the active layer 62, metal materials such as Cr and Mo are deposited on the entire surface, and then patterned to form source and drain electrodes 64 and 66 of the TFT. The ohmic contact layer 60 exposed between the source electrode 64 and the drain electrode 66 is removed by an etching operation and the semiconductor layer 58 is exposed. Next, a passivation layer 68 is entirely formed on the intermediate insulating layer 56 including the exposed semiconductor layer 58 and the source and drain electrodes 64 and 66. At this time, as the material of the protective film 68, BCB, SOG, Acryl, or the like having a relatively small dielectric constant of 3 or less is used to improve the aperture ratio. The portion of the protective film 68 on the drain electrode 66 of the TFT is then removed by etching to form the drain contact hole 70. Thereafter, an indium tin oxide (ITO) material is deposited on the passivation layer 68 on which the drain contact hole 70 is formed by sputtering, and then patterned to form the pixel electrode 72. The pixel electrode 72 is connected to the drain electrode 66 through the drain contact hole 70. By this method, the lower plate of the liquid crystal display device according to the present invention is completed.

 As described above, in the liquid crystal display device and the method of manufacturing the same according to the present invention, an intermediate insulating layer is formed of an organic material containing a predetermined ratio or more of an inorganic material between a gate insulating layer made of an organic material and a semiconductor layer made of an inorganic material. . As a result, the bonding property between the semiconductor layer and the organic film is improved, thereby preventing the semiconductor layer from being lifted up on the insulating layer.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (12)

A liquid crystal display device comprising a gate insulating layer between a gate electrode constituting a thin film transistor of a liquid crystal cell and an active layer. A gate insulating layer made of an organic material and formed flat on the substrate such that a step is not formed by the gate electrode; An intermediate insulating layer formed of a mixed material in which an organic material and an inorganic material are mixed in a predetermined ratio and formed on the gate insulating layer, And an active layer formed on the intermediate insulating layer and formed of a semiconductor material. The method of claim 1, The mixed material is benzocyclobutene (BCB), spin on glass (SOG), and any one organic material of acrylic (Acryl) as a main raw material, characterized in that the inorganic material contains at least 30% or more Liquid crystal display device. The method of claim 1, And the mixed material includes at least one of inorganic materials of Si, O, N, and F. The method of claim 1, The organic material used for the gate insulating layer has a dielectric constant value of 3 or more. The method of claim 1, And the thickness of the intermediate insulating layer is 300 Å or less. Forming a gate insulating layer made of an organic material on the substrate so that a step is not formed by the gate electrode; Forming an intermediate insulating layer on the gate insulating layer, the intermediate insulating layer comprising a mixed material in which an organic material and an inorganic material are mixed in a predetermined ratio; Forming an active layer constituting a thin film transistor of a liquid crystal cell with a semiconductor material on the intermediate insulating layer. The method of claim 6, The mixed material is benzocyclobutene (BCB), spin on glass (SOG), and any one organic material of acrylic (Acryl) as a main raw material, characterized in that the inorganic material contains at least 30% or more Method of manufacturing a liquid crystal display device. The method of claim 6, And at least one of inorganic materials of Si, O, N, and F is included in the mixed material. The method of claim 6, The intermediate insulating layer is a method of manufacturing a liquid crystal display device, characterized in that formed by any one of spin coating, rolling and dipping. The method of claim 6, The thickness of the intermediate insulating layer is 300 Å or less, the manufacturing method of the liquid crystal display element. The method of claim 6, The organic material used for the gate insulating layer has a dielectric constant value of 3 or more. The method of claim 6, The gate insulating layer is a method of manufacturing a liquid crystal display device, characterized in that formed by the spin coating method so that the step is not formed flat.

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