KR100659119B1 - Organic tft, flat panel display therewith, and manufacturing method of the organic tft - Google Patents

Abstract

An organic TFT, a flat panel display therewith, and a method for manufacturing the organic TFT are provided to prevent residues of an organic semiconductor around a bank in a pattering process by performing a plasma process on a surface of the bank. A source electrode(120a) and a drain electrode(120b) are formed on an upper surface of a substrate(110). A bank(130) is formed on upper parts of the source electrode and the drain electrode to expose predetermined parts of the source electrode and the drain electrode. An organic semiconductor layer(140) is formed on upper surfaces of the exposed parts of the source electrode and the drain electrode by a spin-coating method. A gate electrode(160) is isolated from the organic semiconductor layer.

Description

Organic thin film transistor, flat panel display device having same, manufacturing method of organic thin film transistor {organic TFT, flat panel display therewith, and manufacturing method of the organic TFT}

1 is a cross-sectional view schematically showing an organic thin film transistor according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically illustrating a flat panel display device including the organic thin film transistor of FIG. 1.

The present invention relates to an organic thin film transistor and a flat panel display device having the same, and more particularly, to an organic thin film transistor which plasma-processes a bank surface to have hydrophobicity so that an organic semiconductor does not remain around a bank during patterning of an organic semiconductor layer, The present invention relates to a flat panel display device having the same and a method of manufacturing the organic thin film transistor.

Thin film transistors used in flat panel display devices such as liquid crystal display devices, organic electroluminescent display devices, or inorganic electroluminescent display devices (hereinafter referred to as TFTs) are used to drive switching elements and pixels that control the operation of each pixel. Used as a drive element.

On the other hand, the demand for TFT is required not only in display devices but also in various fields. For example, recently, it is used in various fields such as a smart card, an E-paper, a roll-up display, and the like, which is required for thin electronic devices provided therein. Since the common feature is flexibility, the substrate forming the thin film transistor is required to be a substrate having flexibility such as a plastic substrate.

Such a conventional TFT has a source / drain region doped with a high concentration of impurities, a semiconductor layer having a channel region formed between the source / drain region, and a region insulated from the semiconductor layer and corresponding to the channel region. And a gate electrode and a source / drain electrode in contact with the source / drain regions, respectively.

In such a TFT process, a bank is formed to prevent the material forming the semiconductor layer from spreading to other areas. In the process of forming the semiconductor layer after the formation of such a bank, the material forming the semiconductor layer remains on the surface of the bank, thereby lowering the reliability of the TFT.

The present invention provides an organic thin film transistor, a flat panel display device having the same, and an organic thin film transistor, in which an organic semiconductor does not remain around a bank during patterning of an organic semiconductor layer by plasma treating a bank surface to have hydrophobicity. To provide a method of manufacturing.

The organic thin film transistor for solving the technical problem to be achieved by the present invention is a source / drain electrode formed on the substrate; A bank whose surface is hydrophobic to be formed on top of the source / drain electrodes, the bank exposing a portion of the source / drain electrodes; An organic semiconductor layer formed on the exposed source / drain electrodes by a spin coating method; And a gate electrode insulated from the organic semiconductor layer.

According to an aspect of the present invention, a flat panel display device includes: a source / drain electrode formed on an upper surface of a substrate; and a surface of the source / drain electrode formed on an upper surface of the source / drain electrode by hydrophobic treatment; An organic thin film transistor including a bank exposing a predetermined portion, an organic semiconductor layer formed on the exposed source / drain electrodes by a spin coating method, and a gate electrode insulated from the organic semiconductor layer; And a display device electrically connected to the organic thin film transistor.

An organic thin film transistor manufacturing method for solving the technical problem to be achieved by the present invention comprises the steps of forming a source / drain electrode on the substrate; Forming a bank to expose a predetermined portion of the source / drain electrode; Hydrophobizing the surface of the bank; Forming an organic semiconductor layer on the exposed source / drain electrodes by spin coating; And forming a gate electrode to be insulated from the organic semiconductor layer.

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

1 is a cross-sectional view schematically showing an organic thin film transistor according to a preferred embodiment of the present invention.

Referring to FIG. 1, the organic thin film transistor is provided on the substrate 110. The substrate 110 may be, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), polyether imide, polyphenylene Plastic materials such as polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose tri acetate (TAC), cellulose acetate propinonate (CAP) Can be.

The surface of the plastic substrate 110 may be roughened by forming a plasma in which argon (Ar) and oxygen (O 2) are mixed. Alternatively, the plastic substrate 110 may be formed by roughly roughening the surface of the plastic substrate 110. .

Source / drain electrodes 120a and b are formed on the substrate 110 on which the surface is plasma or scratched. The source / drain electrodes 120a and b may be transparent electrodes made of a transparent conductive material such as ITO, IZO, ZnO, or In 2 O 3, and may be Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and the like. It may consist of a reflective electrode containing these compounds and a transparent electrode formed thereon.

After the source / drain electrodes 120a and b are formed, the banks 130 are formed to prevent the organic semiconductor layer 140 material from spreading to other regions. The bank 130 is formed to expose opposite portions of the source / drain electrodes 120a and b. In the opposite portion of the source / drain electrodes 120a and b, an organic semiconductor layer 140 is formed later, and a channel is formed between the source / drain electrodes 120a and b and the organic semiconductor layer 140.

The bank 130 may be made of, for example, inorganic materials such as SiO 2, SiN x, Al 2 O 3, Ta 2 O 5, BST, PZT, etc. by chemical vapor deposition or sputtering. ), Phenolic polymer, acryl polymer, imide polymer such as polyimide, arylether polymer, amide polymer, fluorine polymer, p-xylene polymer, vinyl alcohol polymer, parylene, and It may be composed of an organic material made of a polymeric material such as a compound containing one or more of them.

After forming the bank 130 material on the substrate on which the source / drain electrodes 120a and b are formed and applying a photoresist, a predetermined resist mask (not shown) is formed through a selective exposure and development process. The bank 130 may be dry-etched based on the resist mask to leave only the bank 130 where the opposite portions of the source / drain electrodes 120a.b are exposed, and then the resist mask may be removed. .

After the bank 130 is formed as described above, the surface of the bank 130 is plasma-treated with a fluorine-based gas such as CF4 or C3F8 to have hydrophobicity. In addition, a processing film (not shown) may be formed on the bank 130 to have hydrophobicity. The processed film is a thin coating film of 500 A or less, and is formed of a polymeric fluorine-based material having strong hydrophobic properties. Polymeric fluorine-based materials forming such a processed film include polytetrafluoroethylene, tetrafluoroethylene / perfluorocopolymer, trifluoroethylene / hexafluoropropylene copolymer, perfluorophenylene, perfluorobiphenylene, Perfluoronaphtanylene and the like.

After the surface of the bank 130 is treated to have hydrophobicity, the organic semiconductor layer 140 is formed by using a spin coating method. Since the spin coating method is a known technique, the description thereof is omitted. When the surface of the bank 130 is not hydrophobic, when the organic semiconductor layer 140 is formed by using a spin coating method, the material of the organic semiconductor layer 140 remains on the surface of the bank 130. However, when the surface of the bank 130 is treated to have hydrophobicity to form the organic semiconductor layer 140 by using a spin coating method, the organic semiconductor layer 140 material does not remain on the surface of the bank 130.

Organic semiconductor layer 140 is a polymer, polythiophene and derivatives thereof, polyparaphenylenevinylene and derivatives thereof, polyparaphenylene and derivatives thereof, polyfluorene and derivatives thereof, polythiophenevinylene and derivatives thereof , Polythiophene-heterocyclic aromatic copolymers and derivatives thereof, and as low molecular weights, pentacene, tetracene, oligoacene and derivatives thereof of naphthalene, alpha-6-thiophene, alpha-5-thiophene Oligothiophene and derivatives thereof, phthalocyanine and derivatives thereof with or without metal, pyromellitic dianhydride or pyromellitic diimide and derivatives thereof, perylenetetracarboxylic acid dianhydride or per Relenetetracarboxylic diimide and derivatives thereof.

After the organic semiconductor layer 140 is formed by the spin coating method, a gate insulating layer 150 for insulating the gate electrode 160 to be formed later is formed on one surface thereof. The gate insulating layer 150 may be made of, for example, an inorganic insulating layer such as SiO 2, SiN x, Al 2 O 3, Ta 2 O 5, BST, PZT, etc. by chemical vapor deposition or sputtering. , PS (polystyrene), phenolic polymer, acrylic polymer, imide polymer such as polyimide, arylether polymer, amide polymer, fluorine polymer, p-xylene polymer, vinyl alcohol polymer, parylene ( parylene), and an organic insulating layer made of a polymer material such as a compound containing one or more thereof, and in some cases, may be formed of a plurality of layers. It is preferred that the material be selected from a material which is excellent and has the same or similar thermal expansion coefficient as the substrate.

After the gate insulating layer 150 is formed, the gate electrode 160 is formed thereon. The gate electrode 160 may be a conductive metal such as MoW, Al, Cr, Al / Cr, conductive polyaniline, conductive polypyrrole, conductive polythiopjene, or polyethylene deoxythiophene. Various conductive polymers such as dioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) may be used, such as adhesion to the substrate 110, flatness of the thin films formed on the gate electrode 160, processability for patterning, and subsequent processing. Appropriate materials should be selected in consideration of resistance to the chemicals used.

FIG. 2 is a cross-sectional view schematically illustrating an organic EL device as an example of a pixel unit included in the flat panel display apparatus including the thin film transistor of FIG. 1, according to an exemplary embodiment. The organic thin film transistor unit 100 and The pixel unit 200 is included.

The organic thin film transistor unit 100 includes a bank 130 in which the opposing portions of the substrate 110, the source / drain electrodes 120a and b, and the source / drain electrodes 120a and b are exposed and the surface thereof is hydrophobic. , An organic semiconductor layer 140, a gate insulating layer 150, a gate electrode 160, and a protective layer 170.

The pixel unit 200 includes a first electrode layer 210, a pixel defining layer 220, an organic electroluminescent unit 230, and a second electrode layer 240.

Since the substrate 110 to the gate electrode 160 are the same as those of FIG. 1, description thereof will be omitted.

After the gate electrode 160 is formed, a protective layer 170 such as a passivation layer and / or a planarization layer for insulating and / or planarizing the organic thin film transistor unit 100 is formed thereon.

The first electrode layer 210 is formed on the passivation layer 170, and the first electrode layer 210 is in electrical communication with the organic thin film transistor unit 100 through the via hole 211 formed in the passivation layer 160. Achieve

The first electrode layer 210 may be configured in various ways. For example, the first electrode layer 210 may be a transparent electrode made of a transparent conductive material such as ITO, IZO, ZnO, or In 2 O 3. Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr and a reflective electrode comprising a compound thereof and may be composed of a transparent electrode formed thereon, the first electrode layer 210 is a single layer, Various modifications are possible, including, but not limited to, bilayers.

After the first electrode layer 210 is formed, a pixel defining layer 220 for defining a pixel opening is formed on the top. After the pixel defining layer 220 is formed, the organic electroluminescent unit 230 is provided in at least a region including the pixel opening. As the organic electroluminescent unit 230, a low molecular or polymer organic film may be used. When the low molecular organic film is used, a hole injection layer (HIL), a hole transport layer (HTL), and an emission layer (EML) are emitted. ), An electron transport layer (ETL), an electron injection layer (EIL), or the like, may be formed by stacking a single or a complex structure, and the usable organic material may be copper phthalocyanine (CuPc). , N, N-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (N, N'-Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine: NPB), Various applications are possible, including tris-8-hydroxyquinoline aluminum (Alq3). These low molecular weight organic films are formed by the vacuum deposition method.

In the case of the polymer organic film, the structure may include a hole transporting layer (HTL) and a light emitting layer (EML). In this case, PEDOT is used as the hole transporting layer, and PPV (Poly-Phenylenevinylene) and polyfluorene Polymer organic materials such as polyfluorene) may be used and may be formed by screen printing or inkjet printing. The organic layers constituting the organic electroluminescent unit are not necessarily limited thereto, and various embodiments may be applied.

Similarly, in the case of the first electrode layer 210, the second electrode layer 240 may have various configurations depending on the polarity and the light emission type of the electrode layer. That is, when the second electrode layer 240 acts as a cathode electrode and the light emission type is a bottom emission type, the second electrode layer 240 is Li, Ca, LiF / Ca, LiF / Al, Al, Ag, Mg, and their It may be composed of one or more layers of a material having a small work function, such as a compound, and in the case of a top emission type, an organic electroluminescence unit using Li, Ca, LiF / Ca, LiF / Al, Al, Ag, Mg, and a compound thereof. After forming an electrode for matching the work function on one surface of the 230, a transparent electrode such as ITO, IZO, ZnO, In 2 O 3, or the like may be formed thereon, and the second electrode layer 240 may be entirely formed. It is possible to take various configurations without being limited thereto. Meanwhile, in the above embodiment, the first electrode layer 210 serves as an anode electrode and the second electrode layer 240 serves as a cathode electrode, but various configurations are possible, such as having opposite polarities. Do.

The above embodiments are examples for describing the present invention, and the present invention is not limited thereto, and the thin film transistor according to the present invention may be applied to a liquid crystal display device in addition to an organic electroluminescent display device, and may be used in addition to a flat panel display device. Various modifications may also be considered, such as mounting to the driver circuit which is not implemented.

As described above, according to the present invention, an organic thin film transistor and a flat panel display device having high reliability can be formed by plasma treatment of the bank surface to have hydrophobicity such that organic semiconductors do not remain around the bank during patterning of the organic semiconductor layer.

Claims (6)

A source / drain electrode formed on the substrate; A bank whose surface is hydrophobic to be formed on top of the source / drain electrodes, the bank exposing a portion of the source / drain electrodes; An organic semiconductor layer formed on the exposed source / drain electrodes by a spin coating method; An organic thin film transistor comprising a gate electrode insulated from the organic semiconductor layer. The method of claim 1, wherein the surface of the bank is An organic thin film transistor comprising plasma treatment with a fluorine-based gas. A source / drain electrode formed on the substrate, a surface hydrophobized to be formed on the source / drain electrode, and a bank exposing a predetermined portion of the source / drain electrode; and an upper part of the exposed source / drain electrode An organic thin film transistor including an organic semiconductor layer formed by a spin coating method and a gate electrode insulated from the organic semiconductor layer; And And a display device electrically connected to the organic thin film transistor. 4. The surface of claim 3 wherein the surface of the bank is A flat panel display comprising plasma treatment with a fluorine-based gas. Forming a source / drain electrode on top of the substrate; Forming a bank to expose a predetermined portion of the source / drain electrode; Hydrophobizing the surface of the bank; Forming an organic semiconductor layer on the exposed source / drain electrodes by spin coating; And Forming a gate electrode to be insulated from the organic semiconductor layer. 6. The surface of claim 5 wherein the surface of the bank is A method of manufacturing an organic thin film transistor, characterized by plasma treatment with a fluorine-based gas.

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