KR100749465B1 - Organic thin film transistor, method for manufacturing same, and organic light emitting display device having same - Google Patents

Abstract

The organic thin film transistor according to the present invention includes a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating film and a gate electrode, and a protective film formed on the organic semiconductor layer and a buffer film formed of an inorganic material between the organic semiconductor layer and the protective film. do.

Organic thin film transistor, organic light emitting display, buffer layer, protective layer, organic semiconductor

Description

Organic thin film transistor, method of manufacturing the same, and organic light emitting display device having the same FIELD OF THE SAME AND ORGANIC LIGHT EMITTING DISPLAY HAVING THE SAME

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

2A to 2F are schematic diagrams illustrating a method of manufacturing an organic thin film transistor according to an exemplary embodiment of the present invention.

3 is a cross-sectional view of an organic light emitting diode display according to an exemplary embodiment of the present invention.

The present invention relates to an organic thin film transistor, a method for manufacturing the same, and an organic light emitting display device having the same, and more particularly, to an organic thin film transistor for protecting an organic semiconductor layer and improving adhesion in a manufacturing process, and a method of manufacturing the same. The present invention relates to an organic light emitting display device.

A conventional silicon thin film transistor is formed of a source region and a drain region doped with a high concentration of impurities, a semiconductor layer having a channel region formed between the two regions, a source electrode connected to the source region, and a drain electrode connected to the drain region. do.

Such a silicon thin film transistor is expensive in manufacturing and has a problem in that it is weak to external shocks. In addition, since it is manufactured by a high temperature process, there is a disadvantage that cannot be formed in a plastic substrate or the like used for flexible characteristics.

On the other hand, an organic thin film transistor (OTFT) using an organic semiconductor layer using an organic material may be manufactured at room temperature, unlike a conventional silicon thin film transistor, and thus may be formed on a plastic substrate. Therefore, such organic thin film transistors can be applied to applications such as flexible display devices, smart cards, inventory items or price indicators.

In general, in the process of patterning the organic semiconductor layer, since a general photoresist material cannot be used, a water-soluble photosensitive material is coated and cured to be used as a mask when patterning the organic semiconductor layer.

However, the organic semiconductor layer may be deteriorated by the organic solvent used for coating the water-soluble photosensitive material or the ultraviolet ray used for curing, thereby degrading the characteristics of the organic thin film transistor.

In addition, when the organic semiconductor layer is hydrophobic, the contact between the organic semiconductor layer and the water-soluble photosensitive material may not be good at the time of coating the water-soluble photosensitive material, and thus, the pattern precision of the mask and the patterned organic semiconductor layer may be reduced. have.

The present invention is to solve the problems of the prior art as described above, an object of the present invention is to prevent the damage of the organic semiconductor layer that may occur during patterning and to improve the pattern precision, an organic thin film transistor, a method of manufacturing the same And to provide an organic light emitting display device having the same.

In order to achieve the above object, the organic thin film transistor according to the present invention includes a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating film and a gate electrode, and an inorganic film between the protective film and the organic semiconductor layer and the protective film formed on the organic semiconductor layer. It includes a buffer film formed of a material.

In addition, the organic semiconductor layer, the protective film, and the buffer film may have the same pattern.

In addition, the buffer film may have a thickness of 30 kPa to 500 kPa.

In addition, the buffer film may have a UV transmittance of 50% or less.

In addition, the buffer film may be formed of silicon nitride or a metal.

In addition, the protective film may be formed of polyvinyl alcohol.

In this case, the gate insulating layer, the source and drain electrodes, the organic semiconductor layer, the buffer layer, and the protective layer may be sequentially formed on the gate electrode.

Meanwhile, a method of manufacturing an organic thin film transistor according to the present invention includes forming a gate electrode on a substrate, forming a gate insulating film on the gate electrode, forming a source electrode and a drain electrode on the gate insulating film, and a source electrode. And forming an organic semiconductor material film on the drain electrode, forming a buffer material film made of an inorganic material on the organic semiconductor material film, forming a protective material film on the buffer material film, and patterning the protective material film to form a protective film. And patterning the organic semiconductor material layer and the buffer material layer using the protective layer as a mask to form the organic semiconductor layer and the buffer layer.

In this case, the forming of the buffer material film may be performed by sputtering, chemical vapor deposition (CVD), atomic layer deposition, thermal evaporation, or e-beam evaporation. It can be made by.

In addition, the patterning of the buffer layer and the organic semiconductor layer may be performed by dry etching using the protective layer as a mask.

Meanwhile, the organic light emitting diode display according to the present invention includes an organic thin film transistor including a substrate, a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating film, and a gate electrode, and an organic light emitting element electrically connected to the organic thin film transistor. The organic thin film transistor includes a protective film formed on the organic semiconductor layer and a buffer film formed of an inorganic material between the organic semiconductor layer and the protective film.

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 an organic thin film transistor according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a gate electrode 12 is formed on a substrate 10 of an organic thin film transistor according to an exemplary embodiment of the present invention, and a gate insulating layer 14 covering the gate electrode 12 is formed. In addition, a source electrode 16 and a drain electrode 18 are formed on the gate insulating film 14, and the organic semiconductor layer 20, the buffer film 22, and the protective film () are formed on the source electrode 16 and the drain electrode 18. 24) are laminated in the same pattern.

However, in the present invention, the arrangement of the electrodes and the various insulating films is not limited to this embodiment, and the structure and the arrangement may be variously modified.

The substrate 10 may be made of glass, silicon, plastic or metal. In this case, the plastic applicable to the substrate 10 may include polyethylene terephthalate (PET), polyethylene naphtahlate (PEN), polyether sulfone (PES), polyether imide, Polyphenylene sulfide (PPS), polyallyate, polyimide, polycarbonate (PC), cellulose triacetate, cellulose acetate propionate; CAP).

In addition, the gate electrode 12 may be made of a conductive metal such as MoW, Al, Cr, Al / Cr or a conductive polymer, and the gate insulating layer 14 may be made of benzocyclobutene (BCB), polyimide, and polyvinylphenol (polyvinylphenol), parylene (parylene), epoxy (epoxy), and may be made of organic materials such as poly vinyl chloride (poly vinyl chloride).

In addition, the organic semiconductor layer 20 is a region where a channel is formed during the operation of the transistor. When the organic thin film transistors are positioned, the organic semiconductor layer 20 is patterned in units of organic thin film transistors so as to prevent cross talk between adjacent thin film transistors. . That is, the organic semiconductor layer 20 is insulated from the adjacent organic semiconductor layer (not shown).

The organic semiconductor layer 20 may include pentacene, tetracene, anthracene, naphthalene, fullerene, alpha-6-thiophene, and alpha-4-thi. Offen, oligo thiophene, perylene and its derivatives, rubrene and its derivatives, coronene and its derivatives, perylene tetra carboxylic diimide ) And its derivatives, perylene tetra carboxylic dianhydride and its derivatives, polythiophene and its derivatives, polyparaphenylinvinylene and its derivatives, polyparaphenylin and its derivatives, polyple Lauren and its derivatives, polythiophenevinylene and its derivatives, polythiophene-heterocyclic aromatic copolymers and their derivatives, oligoacenes and derivatives thereof of naphthalene, naphthalene tetra carboxylic aci d diimide) and derivatives thereof, oligothiophenes of alpha-5-thiophene and derivatives thereof, phthalocyanines and derivatives thereof with or without metals, pyromellitic dianhydrides and derivatives thereof, pi Romelitic diimide and derivatives thereof, polyalkylthiophene, polythienylenevinylene, alkylfluorene units, copolymers of alkylthiophenes, and the like. .

The buffer film 22 formed on the organic semiconductor layer 20 may be made of an inorganic material. The buffer layer 22 may be made of, for example, silicon nitride (SiN _X ) or a metal.

In this case, when the UV transmittance of the buffer layer 22 exceeds 50%, too much ultraviolet ray transmitted during curing of the organic semiconductor layer 20 may be transmitted to damage the organic semiconductor layer 20. Therefore, it is preferable that the ultraviolet transmittance of the buffer film 22 has a value of 50% or less.

In addition, the buffer layer 22 may be formed to have a thickness of 30 μs to 500 μs. This may not have a sufficient UV blocking effect when the thickness of the buffer film 22 is less than 30 μs, and the organic semiconductor layer 20 in the deposition process of the buffer film 22 when the thickness of the buffer film 22 exceeds 500 μs. ) May deform and deteriorate characteristics.

In addition, the passivation layer 24 formed on the buffer layer 22 may be formed of polyvinyl alcohol (PVA), which is a water-soluble material. The protective film 24 serves to protect the organic semiconductor layer 20, and is used as a mask for patterning the organic semiconductor layer 20 in the manufacturing process.

In the present embodiment, the organic semiconductor layer 20 is formed in the process of forming the protective film 24 to pattern the organic semiconductor layer 20 by forming the buffer film 22 between the protective film 24 and the organic semiconductor layer 20. To prevent it from being damaged. When the organic semiconductor layer 20 is patterned by using the protective film 24 as a mask, the pattern precision of the organic semiconductor layer 20 can be improved. This will be described in more detail with reference to the manufacturing method of the organic thin film transistor.

A method of manufacturing such an organic thin film transistor will be described with reference to FIGS. 2A to 2G. The materials constituting the respective components are the same as described above, and are not redundantly described when they are not necessary.

2A through 2F are sequential process cross-sectional views illustrating a method of manufacturing an organic thin film transistor according to an exemplary embodiment of the present invention.

First, as shown in FIG. 2A, the gate electrode 12 is formed on the substrate 10. The gate electrode 12 is formed by forming a conductive film by vapor deposition on the entire surface of the substrate 10 and then patterning the conductive film, or by forming a conductive film only in a predetermined region of the substrate 10 using a mask to form the gate electrode 12. ) May be formed. In addition, various methods such as an inkjet printing method may be applied.

Next, as shown in FIG. 2B, an insulating material covering the gate electrode 12 is coated on the entire surface of the substrate 10 to form the gate insulating layer 14.

Next, as shown in FIG. 2C, the source electrode 16 and the drain electrode 18 are formed on the gate insulating film 14. The source electrode 16 and the drain electrode 18 may be formed by forming a conductive film by deposition on the entire surface of the substrate 10 and then patterning the conductive film, or by using a mask only in a predetermined region of the substrate 10. By forming the source electrode 16 and the drain electrode 18. In addition to this, various methods such as an inkjet printing method may be applied.

Next, as shown in FIG. 2D, the organic semiconductor material film 20a and the buffer material film 22a are disposed on the entire surface of the substrate 10 to cover the entire exposed surfaces of the source electrode 16 and the drain electrode 18. ) And the protective material film 24a are sequentially deposited.

In this case, the organic semiconductor material layer 20a may be formed by organic vapor deposition (OVPD), and the buffer material layer 22a may be formed by sputtering and chemical vapor deposition (CVD). , Atomic layer deposition, thermal evaporation, or e-beam evaporation, and the protective material film 24a may be formed by spin coating. Can be.

Accordingly, even when the buffer material film 22a is positioned between the organic semiconductor material film 20a and the protective material film 24a, the protective material film 24a is excellent even when the organic semiconductor material film 20a is made of a hydrophobic material. It may be formed uniformly while having adhesiveness.

Next, as shown in FIG. 2E, the protective material film is patterned to form the protective film 24. In this case, the passivation layer 24 may be formed by exposing and developing ultraviolet rays using a mask.

In this case, since the ultraviolet rays are blocked by the buffer material layer 22a having low UV transmittance during the ultraviolet curing process of the protective layer 24, the organic semiconductor material layer 20a is not exposed to ultraviolet rays. As a result, it is possible to prevent damage to the organic semiconductor material film 20a, which may have occurred in the conventional UV curing process.

As described above, since the protective material film 24a and the buffer material film 22a have excellent adhesion, the pattern precision of the buffer film 22 may be improved. Next, as shown in Fig. 2F, the buffer material film (22a in Fig. 2E, hereinafter identical) and the organic semiconductor material film (20a in Fig. 2E, hereinafter identical) are patterned using the protective film 24 as a mask. 22 and the organic semiconductor layer 20 are formed. As a result, the buffer film 22 and the organic semiconductor layer 20 have the same pattern as the protective film 24. In this case, the buffer layer 22 and the organic semiconductor layer 20 may be patterned by, for example, dry etching.

Here, the pattern precision of the buffer film 22 used as a mask may be improved as described above, and thus the pattern precision of the organic semiconductor layer 20 may also be improved.

Meanwhile, the above-described organic thin film transistor may be applied to an organic light emitting diode display, which will be described with reference to FIG. 3.

3 is a cross-sectional view schematically illustrating an organic light emitting display device according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the organic thin film transistor TFT1 is formed on the substrate 10. 3 illustrates an organic thin film transistor according to an exemplary embodiment of the present invention as an example, but the present invention is not limited thereto.

A passivation film 26 made of SiO ₂ or the like is formed on the organic thin film transistor TFT1, and a pixel defining film 28 made of acryl, polyimide, or the like is formed on the passivation film 26. The passivation film 26 may serve as a protective film for protecting the organic thin film transistor TFT1 and may serve as a planarization film for planarizing an upper surface thereof.

Although not shown, at least one capacitor may be connected to the organic thin film transistor TFT1. The circuit including the organic thin film transistor TFT1 is not necessarily limited to the example illustrated in FIG. 3, and may be variously modified.

Meanwhile, the drain electrode 18 is connected to the light emitting device 30 through the via hole 26a formed in the passivation film 26. The light emitting element 30 includes a pixel electrode 32 and a counter electrode 34 opposed to each other, and an intermediate layer 36 interposed between the electrodes and including at least a light emitting layer. The counter electrode 34 may be formed in common in a plurality of subpixels, and various modifications may be possible.

Meanwhile, although the intermediate layer 36 is illustrated in FIG. 3 so as to correspond only to the subpixels, this is illustrated for convenience of description of the configuration of the subpixels, and the intermediate layer 36 may be formed integrally with the intermediate layer of the adjacent subpixels. It may be.

In addition, some of the layers of the intermediate layer 36 may be formed for each subpixel, and other layers may be formed integrally with the intermediate layer of the adjacent subpixels.

The pixel electrode 32 functions as an anode electrode, and the counter electrode 34 functions as a cathode electrode. Of course, the polarity of the pixel electrode 32 and the counter electrode 34 may be reversed. In addition, the pixel electrode 32 and the drain electrode 18 are electrically connected to each other, and they may be integrally formed.

The pixel electrode 32 may be provided as a transparent electrode or a reflective electrode. When the pixel electrode 32 is used as a transparent electrode, it may include ITO, IZO, ZnO, or In ₂ O ₃ . In addition, when the pixel electrode 32 is used as a reflective electrode, a first layer made of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, a compound thereof, or the like, and on the first layer It may be formed in a multi-layered structure including a second layer formed of ITO, IZO, ZnO or In ₂ O ₃ and the like.

The counter electrode 34 may also be provided as a transparent electrode or a reflective electrode. When the counter electrode 34 is used as a transparent electrode, a first layer made of Li, Ca, LiF / Ca, LiF / Al, Al, Mg, and a compound thereof, and formed on the first layer and formed of ITO, IZO, ZnO or And a second layer including In ₂ O ₃ , and the like. In this case, the second layer may be formed of an auxiliary electrode or a bus electrode line.

When the counter electrode 34 is used as a reflective electrode, Li, Ca, LiF / Ca, LiF / Al, Al, Mg, or a compound thereof is deposited on the entire surface.

The intermediate layer 36 provided between the pixel electrode 32 and the counter electrode 34 may include a low molecular weight organic material or a high molecular weight organic material.

When the intermediate layer 36 includes a low molecular weight organic material, a hole injection layer (HIL), a hole transport layer (HTL), an organic emission layer (EML), an electron transport layer (ETL) ), And an electron injection layer (EIL) may be formed by stacking a single or a composite structure.

At this time, usable organic substances include copper phthalocyanine (CuPc), N, N-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (N, N'-Di (naphthalene-1-) yl) -N, N'-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum (Alq ₃ ), and the like. These low molecular weight organic materials are vacuum vapor deposition using masks. It can be formed as.

When the intermediate layer 36 includes a polymer organic material, the intermediate layer 36 may have a structure including a hole transport layer (HTL) and a light emitting layer (EML), wherein the hole transport layer includes polyethylene dioxythiophene and the light emitting layer is poly-phenyl. Poly-Phenylenevinylene (PPV) -based or polyfluorene-based materials may be included.

Since the organic thin film transistors can be manufactured to be flexible, the organic light emitting diode display including the organic thin film transistors can have a flexible characteristic.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As described above, according to the organic thin film transistor and the manufacturing method thereof according to the present invention, by providing a buffer film between the organic semiconductor layer and the protective film it is possible to prevent damage to the organic semiconductor layer when forming the protective film to improve the characteristics of the organic thin film transistor Can be improved.

And the adhesiveness between a protective film and an organic semiconductor layer can be improved, and the pattern precision of the protective film used as a mask of an organic semiconductor layer can be improved. As a result, the pattern precision of an organic semiconductor layer can be improved.

According to the organic light emitting diode display according to the present invention, an organic thin film transistor having excellent characteristics can be provided to improve display characteristics.

Claims (17)

An organic thin film transistor comprising a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating film, and a gate electrode, A protective film formed on the organic semiconductor layer; And A buffer film formed of an inorganic material between the organic semiconductor layer and the protective film, The buffer film is an organic thin film transistor having a UV transmittance of 50% or less. According to claim 1, And the organic semiconductor layer, the protective film, and the buffer film have the same pattern. According to claim 1, The buffer film is an organic thin film transistor having a thickness of 30 ~ 500Å. delete According to claim 1, The buffer film is an organic thin film transistor formed of silicon nitride or a metal. According to claim 1, The protective film is an organic thin film transistor formed of polyvinyl alcohol. According to claim 1, And the gate insulating layer, the source and drain electrodes, the organic semiconductor layer, the buffer layer, and the passivation layer are sequentially formed on the gate electrode. Forming a gate electrode on the substrate; Forming a gate insulating film on the gate electrode; Forming a source electrode and a drain electrode on the gate insulating film; Forming an organic semiconductor material film on the source electrode and the drain electrode; Forming a buffer material film formed of silicon nitride or a metal on the organic semiconductor material film; Forming a protective material film on the buffer material film; Patterning the protective material film to form a protective film; And Patterning the organic semiconductor material layer and the buffer material layer using the protective layer as a mask to form an organic semiconductor layer and a buffer layer Method for manufacturing an organic thin film transistor comprising a. The method of claim 8, And the buffer material film is formed by sputtering, chemical vapor deposition, atomic layer deposition, thermal evaporation, or electron beam deposition. The method of claim 8, And the buffer material film and the organic semiconductor material film are patterned by dry etching. Board; An organic thin film transistor including a source electrode, a drain electrode, an organic semiconductor layer, a gate insulating film, and a gate electrode; And An organic light emitting device electrically connected to the organic thin film transistor Including, The organic thin film transistor, A protective film formed on the organic semiconductor layer; And A buffer film formed of an inorganic material between the organic semiconductor layer and the protective film, The buffer layer has an UV transmittance of 50% or less. The method of claim 11, wherein The organic light emitting diode display of which the organic semiconductor layer, the passivation layer and the buffer layer have the same pattern. The method of claim 11, wherein The buffer layer has a thickness of 30 to 500 kHz. delete The method of claim 11, wherein The buffer layer is formed of silicon nitride or a metal. The method of claim 11, wherein The passivation layer is formed of polyvinyl alcohol. The method of claim 11, wherein In the organic thin film transistor, the gate insulation layer, the source and drain electrodes, the organic semiconductor layer, the buffer layer, and the passivation layer are sequentially formed on the gate electrode.

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