KR20080066338A - Thin film transistor and flat panel display using the thin film transistor - Google Patents

Abstract

A thin film transistor is provided to avoid a contact defect between a source/drain electrode and a semiconductor layer by forming a gate insulation layer whose part is made of an inorganic insulation layer and by forming an organic insulation layer in a region except the inorganic insulation layer. A source/drain electrode(40,50), a semiconductor layer(60) and a gate electrode(20) are formed on a substrate(10). An inorganic insulation layer(30) is formed between the semiconductor layer and the gate electrode. An organic insulation layer(31) is formed in a region except the inorganic insulation layer. The semiconductor layer can be one selected from a group of amorphous silicon, polycrystalline silicon, compound semiconductor, oxide semiconductor and organic semiconductor. The substrate can be one of plastic, a metal thin film or micro glass.

Description

Thin film transistor and flat panel display using the thin film transistor

1 illustrates a cross-sectional structure of a flat panel display device according to an example of the present invention.

2A to 2B are views for explaining various examples of the thin film transistor.

3 is a view for explaining an example of a method of forming a thin film transistor.

***** Explanation of symbols for the main parts of the drawing *****

10 substrate 20 gate electrode

30 inorganic insulating film 31 organic insulating film

40 source electrode 50 drain electrode

60 semiconductor layer 70 protective film

80: via hole 90: pixel electrode

100: organic film layer 110: common electrode

The present invention relates to a thin film transistor and a flat panel display device using the same.

Thin film transistors used in flat panel display devices such as liquid crystal display (LCD) and electroluminescent display (LED) are used as switching elements for controlling the operation of each pixel and driving elements for driving the pixels. .

The thin film transistor includes a source electrode and a drain electrode, and a semiconductor layer formed between the source electrode and the drain electrode, and a gate electrode insulated from the source electrode, the drain electrode, and the semiconductor layer.

Meanwhile, recently, a flexible display that realizes an image using a flexible substrate as a next generation display has attracted attention. In the case of using a flexible substrate as described above, an insulating film having a flexible property is used between the semiconductor layer and the gate electrode so that the thin film transistor also has a flexible property.

However, in such a case, poor contact between the source and drain electrodes and the semiconductor layer may cause a problem such as stability and reliability of the device, which may cause a pixel defect.

The present invention provides a thin film transistor and a flat panel display device having improved stability and reliability of the device by preventing contact failure between the source and drain electrodes and the semiconductor layer while appropriately performing a buffer against shock or physical deformation from the outside. Its purpose is to.

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

According to an exemplary embodiment of the present invention, a thin film transistor includes a source or drain electrode, a semiconductor layer, and a gate electrode formed on a substrate, and an inorganic insulating layer and an inorganic layer formed between the semiconductor layer and the gate electrode. An organic insulating film formed in a region other than the insulating film is included.

In addition, the organic insulating film may be selected from benzo cyclobutane, polyvinylphenol, polyimide and parylene, and the inorganic insulating film may be selected from SiOx, SiNx and SiON.

In addition, the semiconductor layer may be any one selected from the group consisting of amorphous silicon, polycrystalline silicon, compound semiconductor, oxide semiconductor, and organic semiconductor.

In addition, the substrate may be either a plastic or metal thin film or micro glass.

In addition, a flat panel display device according to an exemplary embodiment of the present invention may include a thin film transistor, a pixel electrode connected to at least one of a source or drain electrode of the thin film transistor, an organic film layer on the pixel electrode, and a common electrode on the light emitting layer. Include.

In addition, the organic film layer may include an organic light emitting layer formed of an organic material.

In addition, the thin film transistor may be at least one of a switching thin film transistor and a driving thin film transistor. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates a cross-sectional structure of a flat panel display device according to an example of the present invention.

A flat panel display device may be classified into a liquid crystal display device (LCD), an electroluminescent display device (LED), and the like. In FIG. 1, an electroluminescent display device including a thin film transistor is described as an example.

As shown, the electroluminescent display device includes a thin film transistor and a light emitting device connected to the thin film transistor on the substrate 10.

The thin film transistor includes a substrate 10, a gate electrode 20, gate insulating layers 30 and 31, a source electrode 40 and a drain electrode 50, a semiconductor layer 60, and a protective layer 70.

The substrate 10 may be selected from any one of plastic or metal thin film or micro glass having flexible properties. Plastics, for example, are polyethersulfone (PES), polyacrylate (PAR), polyether amide (PEI), polyethylene naphthalate (PET), polyethylene terephthalate (PET), etc. It may include a substance.

As such, the substrate 10 may have a flexible property, and thus, may act as a buffer to prevent the substrate 10 from being easily broken due to physical deformation or impact from the outside during or after the manufacturing process of the flat panel display device. .

The gate electrode 20 is formed on the substrate 10 to control a channel to be formed in the semiconductor layer 60, and to control aluminum, aluminum alloy, copper (Cu), tungsten (W), tantalum (Ta), and the like. It may be formed by selecting one of the conductive metal group including molybdenum (Mo).

The gate insulating films 30 and 31 are formed on the substrate 10 to cover the gate electrode 20, and the inorganic insulating film 30 and the inorganic insulating film 30 formed between the semiconductor layer 60 and the gate electrode 20. And an organic insulating film 31 formed in a region other than). As described above, the organic insulating layer 31 formed on the substrate 10 may be patterned so that the inorganic insulating layer 30 and a predetermined region overlap.

In this way, the gate insulating films 30 and 31 are formed of the inorganic insulating film 30 only between the semiconductor layer 60 and the gate electrode 20, so that the entire gate insulating films 30 and 31 are formed of the inorganic insulating film 30. In addition to ensuring the same level of reliability as the case, it is possible to prevent device performance deterioration and nonuniformity, which is a problem when the gate insulating films 30 and 31 are formed only of the organic insulating film 31, and to improve process convenience.

In addition, by minimizing the formation region of the inorganic insulating film 30 of the gate insulating film 30, 31, by dispersing or minimizing the stress generated between the inorganic insulating film 30 and the flexible substrate 10, the inorganic insulating film 30 In addition to preventing the problem of cracking), the inorganic insulating film 30 is formed only in adjacent regions of the source electrode 40 and the drain electrode 50, which are bonded to the semiconductor layer 60. The defect of the thin film transistor due to the crack between the semiconductor layer 60 and the source or drain electrodes 40 and 50, which may occur due to the bending of 10, may be minimized.

In addition, the organic insulating film 31 is formed in a region other than the inorganic insulating film 30 among the gate insulating films 30 and 31, so that the performance and reliability of the device can be maintained at an appropriate level, while the buffer against physical deformation or impact from the outside. Can play the role appropriately.

Such an organic insulating film 31 may be selected from benzocyclobutane, polyvinylphenol, polyimide and parylene, and the inorganic insulating film 30 may be selected from SiOx, SiNx and SiON.

In addition, the organic insulating layer 31 and the inorganic insulating layer 30 may be formed as a single layer, or a plurality of layers may be stacked.

The source electrode 40 and the drain electrode 50 are formed on the gate insulating films 30 and 31.

The semiconductor layer is formed between the source electrode 40 and the drain electrode 50 and the gate insulating films 30 and 31, and forms a channel by the voltage supplied from the gate electrode 20 to form the source electrode 40 and the drain electrode. Let 50 be conductive with each other. The semiconductor layer 60 may be any one selected from the group consisting of amorphous silicon, polycrystalline silicon, compound semiconductor, oxide semiconductor, and organic semiconductor.

The passivation layer 70 may be formed on the substrate 10 to cover at least one of the source electrode 40, the drain electrode 50, the gate insulating layers 30 and 31, or the semiconductor layer 60. It may be formed by depositing or applying one selected from the group of organic insulating materials including (acryl) resin, fluoropolyaryl ether (FPAE), cytotopes and perfluorocyclobutane (PFCB).

Although the thin film transistor has been described as an example of the driving thin film transistor in FIG. 1, the switching thin film transistor is also formed of an inorganic insulating film 30 between the semiconductor layer 60 and the gate electrode 20 among the gate insulating films 30 and 31. The organic insulating film 31 can be formed in a region other than the inorganic insulating film 30.

The light emitting device is connected to at least one of the source electrode 40 or the drain electrode 50 through the via hole 80 on the passivation layer 70.

Such a light emitting device includes a pixel electrode 90, an organic layer 100, and a common electrode 110.

The pixel electrode 90 is connected to at least one of the source or drain electrodes 40 and 50 of the thin film transistor, and may include a material such as indium tin oxide (ITO), which is a light transmissive material.

The organic layer 100 is positioned on the pixel electrode 90 and includes at least one organic layer selected from the group consisting of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole barrier layer. The light emitting layer may include an organic light emitting layer formed of an organic material.

The common electrode 110 is positioned on the emission layer and may include aluminum (Al).

As shown in FIG. 1, the electroluminescent display device may be formed such that the via hole 80 is connected to the source electrode 40 and the drain electrode 50, and the source electrode 40 and the drain electrode 50. ) And a predetermined material may be further added to lower the electrical resistance of the semiconductor layer 60 and increase the adhesiveness.

In addition, in order to prevent cracks that may occur in the protective film 70 and to increase stability, the protective film 70 may be formed by stacking a plurality of layers.

2A to 2B are views for explaining various examples of the thin film transistor.

Unlike the Inverted Staggered type thin film transistor shown in FIG. 1, as in the Inverted Staggered type thin film transistor shown in FIG. 2A, the portion of the inorganic insulating film 30 of the gate insulating films 30 and 31 is a source on the substrate 10. It may be formed to protrude further than the electrode 40 and the drain electrode 50.

In this way, even if the substrate 10 is bent due to external impact or physical deformation, the wider portion of the inorganic insulating film 30 is not bent, so that the semiconductor layer 60 and the source or drain electrodes 40 and 50 are not bent. The stability can be further increased, further minimizing the crack between the semiconductor layer 60 and the source or drain electrodes 40 and 50, and further improving the device performance and reliability of the thin film transistor.

Also, as shown in FIG. 2B, in the case of the Inverted Coplanar type thin film transistor in which the semiconductor layer 60 is formed on the source electrode 40 and the drain electrode 50, as shown in (a) or (b). The inorganic insulating layer 30 may be formed between the semiconductor layer 60 and the gate electrode 20 of the gate insulating layers 30 and 31, and the remaining portion may be formed of the inorganic insulating layer 30.

In addition, as shown in FIGS. 2C and 2D, in the case of a staggered type or a coplanar type thin film transistor in which the gate electrode 20 is not directly formed on the substrate 10 and formed on the gate insulating layers 30 and 31. Also, the inorganic insulating film 30 is formed between the semiconductor layer 60 and the gate electrode 20 among the gate insulating films 30 and 31, and the remaining part is formed of the inorganic insulating film 30. Appropriate device performance and reliability, while protecting the thin film transistor from external shocks.

3 is a view for explaining an example of a method of forming a thin film transistor.

First, as shown in (a), the gate electrode 20 is patterned and formed on the substrate 10.

Subsequently, the inorganic insulating film 30 is partially patterned to cover the gate electrode 20 on the substrate 10 as shown in (b), and the organic insulating film 31 is formed at portions other than the inorganic insulating film 30. Form. In FIG. 1B, an example in which the organic insulating layer 31 does not overlap with a portion of the inorganic insulating layer 30 is illustrated, but as shown in FIG. 1, a portion of the organic insulating layer 31 overlaps with a portion of the inorganic insulating layer 30. You may.

Thereafter, as shown in (c), the semiconductor layer 60 is formed on the inorganic insulating film 30, and as shown in (d), the source electrode 40 and the drain electrode 50 are in contact with the semiconductor layer 60. Form some by overlapping.

By forming the thin film transistor in this manner, even when the substrate 10 is flexible and bent by an external impact, only the portion where the organic insulating layer 31 is formed is bent, and the portion where the inorganic insulating layer 30 is formed is not bent. It is possible to ensure stability and reliability so that cracks or defects do not occur between the semiconductor layer 60, the source electrode 40, and the drain electrode 50.

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive.

The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

As described above, in the thin film transistor and the flat panel display device according to the present invention, part of the gate insulating film is formed of an inorganic insulating film and an organic insulating film is formed in other areas, thereby providing a buffer against shock or physical deformation from the outside. Properly performed, the contact failure between the source and drain electrodes and the semiconductor layer can be prevented to further improve the stability and reliability of the device.

Claims (7)

A source or drain electrode, a semiconductor layer, and a gate electrode formed on the substrate, An inorganic insulating film formed between the semiconductor layer and the gate electrode; And An organic insulating film formed in a region other than the inorganic insulating film; Thin film transistor comprising a. According to claim 1, The organic insulating film is selected from benzo cyclobutane, polyvinylphenol, polyimide and parylene, The inorganic insulating film is selected from SiOx, SiNx and SiON Thin film transistor, characterized in that. The method of claim 1, The semiconductor layer Any one selected from the group consisting of amorphous silicon, polycrystalline silicon, compound semiconductors, oxide semiconductors and organic semiconductors Thin film transistor, characterized in that. The method of claim 1, The substrate is Either plastic or metal thin film or microglass Thin film transistor, characterized in that. The thin film transistor of claim 1; A pixel electrode connected to at least one of the source or drain electrodes of the thin film transistor; An organic layer disposed on the pixel electrode; And A common electrode on the light emitting layer; Flat panel display device comprising a. The method of claim 5, wherein The organic layer includes an organic light emitting layer formed of an organic material Flat panel display device characterized in that. The method of claim 2, Wherein the thin film transistor is a thin film transistor is at least one of a switching thin film transistor or a driving thin film transistor Flat panel display device characterized in that.

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