KR100696548B1 - Flat panel display device and manufacturing method thereof - Google Patents

Abstract

A flat panel display device and a method for manufacturing the same are provided to prevent a problem such as an electric short between a substrate and a device or crystallization by solving a surface roughness problem of a metal surface. A method for manufacturing a flat panel display device includes the steps of: forming an insulating layer on a metal substrate(10); smoothing a surface of the insulating layer by processing an upper surface of the insulating layer; and forming a light emitting device on the insulating layer, wherein the upper surface of the metal surface has a roughness. The smoothing process is performed by etching the upper surface of the insulating layer with a BOE(Buffer Oxide Etchant).

Description

Flat panel display device and manufacturing method

1A to 1C are cross-sectional views sequentially illustrating an example of a method for smoothing a surface of a conventional metal substrate;

2a to 2c are cross-sectional views sequentially showing an example of the surface smoothing treatment method of a metal substrate according to the present invention;

3 is a cross-sectional view schematically illustrating an organic light emitting display device as an example of a flat panel display device of the present invention using a metal substrate manufactured according to FIGS. 2A to 2C.

The present invention relates to a flat panel display and a manufacturing method thereof, and more particularly, to a flat panel display using a metal substrate and a method for manufacturing the same.

In general, a flat panel display such as an organic light emitting display, a TFT-LCD, and the like can be ultra-thin and flexible in view of driving characteristics, and thus many studies have been made.

In order to make the flat panel display thin and flexible, a flexible substrate is used. As the flexible substrate, a substrate made of a synthetic resin material is generally used. However, since the flat panel display devices have various structures such as an organic film, a thin film transistor layer for driving, an electrode layer, or an alignment film according to their characteristics, a very difficult process condition for forming them is also required. Therefore, when the substrate of the synthetic resin material is used, the substrate is deformed or the thin film layers formed on the substrate are deformed by the above process conditions.

In order to overcome the limitations of the synthetic resin substrate, a technique of using a metal foil as a substrate instead of the synthetic resin substrate has recently been studied.

When the metal foil is used as a substrate, it is sufficient to be used as a top emission type structure, and may be relatively less sensitive to process conditions because a high temperature process such as crystallization of amorphous silicon with polysilicon may be performed.

However, a major problem of such a metal substrate is the surface roughness of the surface. That is, the surface of the metal substrate has a myriad of pointed protrusions 11 on the surface, as shown in FIG. 1A, so that the elements formed thereon through the insulating film by the protrusions 11 are separated from the metal substrate 10. It may cause an electrical short or may cause a problem in crystallization when amorphous silicon is crystallized to polysilicon.

For this reason, a metal substrate is used by processing the surface smoothly, ie, smoothly.

1A to 1C illustrate a smoothing method of a metal substrate 10, which is generally used in the related art. As shown in FIG. 1A, the surface of the metal substrate 10 having the protrusions 11 swelling up may be a conventional CMP ( After the process is performed smoothly by chemical mechanical polishing), the buffer layer 20 is formed of an inorganic or organic compound, as shown in FIG. 1C, on the processed metal substrate 10.

By the way, in the case of such a conventional method, since the CMP process is very expensive, there is a limit that is difficult to apply in practice.

In addition to the above method, there is also a method of forming a thick insulating film such as SOG as the buffer layer 20, but in this case, since the formation of a thick SOG proceeds at a high cost, it is inferior in mass productivity.

The present invention has been made to solve the above problems, and an object thereof is to provide a flat panel display device that can easily solve the problem of surface roughness of a metal substrate.

In order to achieve the above object, the present invention includes the steps of forming an insulating film on a metal substrate, processing the upper surface of the insulating film to smooth the surface, and forming a light emitting element on the insulating film A manufacturing method of a flat panel display device is provided.

The present invention also comprises a metal substrate, an insulating film formed on the metal substrate, and a light emitting element formed on the insulating film in order to achieve the above object, the metal substrate is a state that is not smoothed to the surface And the insulating film is smoothly processed on its top surface.

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

2A through 2C are cross-sectional views sequentially illustrating a process of manufacturing a metal substrate for a flat panel display device according to an exemplary embodiment of the present invention.

As shown in FIG. 2A, a metal substrate 10 having a plurality of protrusions 11 formed on a surface thereof is prepared. The metal substrate 10 may include at least one selected from the group consisting of stainless steel, Ti, Mo, Invar alloy, Inconel alloy, and Kovar alloy. Preferably, stainless steel may be used.

The protrusions 11 rising on the metal substrate 10 are formed by the surface roughness of the metal substrate 10, and the average height thereof is about 1,000 m 3. The surface of the metal substrate 10 may be processed to some extent, but the state of the metal substrate 10 is not subjected to the high smoothing process such as CMP.

As shown in FIG. 2B, the buffer layer 20 is formed of an insulating material on the metal substrate 10 in this state. The buffer layer 20 may be formed of an organic compound or an inorganic compound, and the thickness of the buffer layer 20 is greater than the thickness of the protrusion 11 of the metal substrate 10.

When the buffer layer 20 is formed on the metal substrate 10 which is not surface-processed as described above, the surface state of the metal substrate 10 is transferred to the buffer layer 20, and the surface of the buffer layer 20 is rough. Therefore, the protrusions 21 also rise on the surface of the buffer layer 20.

In this state, as shown in FIG. 2C, the surface of the buffer layer 20 is processed. The surface of the buffer layer 20 is etched with BOE (Buffered Oxide Etchant) to smoothly process the surface. The BOE may be a mixture of HF: NH4F: DI (DeIonized Water) is 6:30:64 wt%.

The surface of the etched buffer layer 20 is plasma treated.

In this case, the surface of the buffer layer 20 is smoothly formed, so that the problem of the surface roughness of the metal substrate 10 can be easily solved, and the surface processing can be performed at a lower cost than in the case of the related art.

FIG. 3 illustrates a state in which an organic light emitting display device is formed on the metal substrate 10 and the buffer layer 20 manufactured according to FIGS. 2A to 2C.

After the semiconductor active layer 31 arranged in a predetermined pattern is formed on the buffer layer 20, the semiconductor active layer 31 is embedded by the gate insulating layer 32. The semiconductor active layer 31 has a source region 31b and a drain region 31c, and further includes a channel region 31a therebetween. The semiconductor active layer 31 may be formed by forming an amorphous silicon film on the buffer layer 20, crystallizing it into a polycrystalline silicon film, and patterning the polycrystalline silicon film. The source and drain regions 31b and 31c of the semiconductor active layer 31 are doped with impurities according to the type of TFT such as the driving TFT M1 and the switching TFT M2. 2 and 5 illustrate the PMOS type driving TFT M1, but the present invention is not limited thereto, and the PMOS type driving TFT M1 may be formed as an NMOS type.

The gate electrode 33 corresponding to the semiconductor active layer 31 and the interlayer insulating layer 34 filling the gate insulating layer 32 are formed on the upper surface of the gate insulating layer 32.

After contact holes are formed in the interlayer insulating layer 34 and the gate insulating layer 32, the source electrode 35 and the drain electrode 36 are respectively formed on the interlayer insulating layer 34. And the drain region 31c.

The passivation film 37 is formed on the thin film transistor TFT, and the pixel electrode 41 of the organic light emitting diode OLED is formed on the passivation film 37. The pixel electrode 41 is contacted with the drain electrode 36 of the thin film transistor TFT by the via hole formed in the passivation film 37. The passivation film 37 may be formed of an inorganic material and / or an organic material. As shown in FIG. 3, the passivation film 37 may be formed as a flattening film so that the top surface is flat regardless of the bending of the lower film. It may be formed to go along the bend.

After the pixel electrode 41 is formed on the passivation film 37, the pixel defining layer 38 is formed of an organic material and / or an inorganic material so as to cover the pixel electrode 41 and the passivation film 37. The electrode 41 is opened so as to be exposed.

The organic emission layer 42 and the counter electrode 43 are formed on at least the pixel electrode 41.

The pixel electrode 41 functions as an anode electrode, and the counter electrode 43 functions as a cathode electrode. Of course, the polarities of the pixel electrode 41 and the counter electrode 43 may be reversed. It's okay.

The pixel electrode 41 may be formed of a material having a high work function, and may be formed to include transparent conductors such as ITO, IZO, In 2 O 3, and ZnO.

The counter electrode 43 may be provided to include metal materials such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, and compounds thereof having a low work function.

The pixel electrode 41 and the counter electrode 43 are insulated from each other by the organic layer 42, and light is emitted from the organic layer 42 by applying voltages having different polarities to the organic layer 42.

The organic layer 42 may be a low molecular or high molecular organic film. When using a low molecular organic film, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), an electron injection layer (EIL) : Electron Injection Layer) can be formed by stacking single or complex structure, and usable organic materials are 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 ( Alq3) can be used in various ways. These low molecular weight organic films are formed by the vacuum deposition method. In this case, the hole injection layer, the hole transport layer, the electron transport layer, the electron injection layer and the like can be commonly applied to red, green, and blue pixels as a common layer. Thus, unlike FIG. 3, these common layers may be formed to cover the entire pixels, such as the counter electrode 43.

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 polyvinylvinylene (PPV) and polyfluorene are used as the emitting layer. Polymer organic materials such as (Polyfluorene) are used and can be formed by screen printing or inkjet printing.

The organic layer as described above is not necessarily limited thereto, and various embodiments may be applied.

After the organic light emitting diode OLED is formed, the organic light emitting diode OLED is sealed and shielded from outside air.

In the organic light emitting diode display according to the present invention, since the surface of the metal substrate 10 is not CMP treated, the surface roughness is maintained in a large state.

Although the above embodiments have been described with respect to an organic light emitting display, the present invention can be applied to various kinds of flat panel displays such as a liquid crystal display in addition to the organic light emitting display.

According to the present invention as described above, it is possible to solve the surface roughness problem of the metal substrate without expensive CMP treatment, it is possible to prevent the electrical short, crystallization problem and the like of the substrate and the device in advance.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (11)

Forming an insulating film on the metal substrate; Processing the upper surface of the insulating film to smooth the surface; And Forming a light emitting element on the insulating film; And the metal substrate has a roughened top surface thereof. The method of claim 1, The surface roughness of the upper surface of the metal substrate is a manufacturing method of a flat panel display device. The method of claim 1, And forming the insulating layer is performed in a state where a process of smoothing the surface of the metal substrate is not performed. The method of claim 1, The step of smoothing the surface by processing the upper surface of the insulating film is a step of etching the surface of the insulating film with BOE (Buffered Oxide Etchant) to smooth the surface. The method of claim 4, wherein Processing the upper surface of the insulating film to smooth the surface includes performing a plasma treatment on the surface of the insulating film. The method according to any one of claims 1 to 5, And the insulating film includes an inorganic compound or an organic compound. The method according to any one of claims 1 to 5, And the metal substrate comprises at least one selected from the group consisting of stainless steel, Ti, Mo, Invar alloy, Inconel alloy, and Kovar alloy. Metal substrates; An insulating film formed on the metal substrate; And A light emitting element formed on the insulating film; The metal substrate is a state in which a smoothing process is not performed on its surface, and the insulating film is a flat upper surface thereof is processed smoothly. The method of claim 8, And the insulating layer includes an inorganic compound or an organic compound. The method of claim 8, And the metal substrate comprises at least one selected from the group consisting of stainless steel, Ti, Mo, Invar alloy, Inconel alloy, and Kovar alloy. The method according to any one of claims 8 to 10, And a surface roughness of the upper surface of the metal substrate is 1,000 GPa.

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