KR100813852B1 - A method for manufacturing organic electro-luminescent display device - Google Patents

Abstract

An organic light-emitting diode device and a method for fabricating the same are provided to improve a morphology characteristic of a planarization layer by removing an undercut formed on the planarization layer. An organic light-emitting diode device includes at least one thin film transistor, a passivation layer(50), a planarization layer(59), and an organic light emitting device. The thin film transistor is formed on a substrate(50), and has a semiconductor active layer(52), a gate electrode(54), a source electrode(56) and a drain electrode(57). The gate electrode is insulated from the semiconductor active layer. The source and drain electrodes are contacted with the semiconductor active layer. The passivation layer covers the thin film transistor and has a first aperture which exposes the source and drain electrodes. The planarization layer covers the passivation layer and has a second aperture which exposes the source and drain electrodes. The organic light emitting device is electrically connected to the thin film transistor through the first and second apertures. An edge of the second aperture formed on an upper part of the first aperture is expanded to cover an internal plane of the first aperture.

Description

Organic electroluminescent display and method for manufacturing same {A method for manufacturing organic electro-luminescent display device}

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

2 is a plan view of an organic light emitting display device according to an exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view of a portion of the organic light emitting display device of FIG. 2.

4 is a flowchart illustrating a method of manufacturing an organic light emitting display device according to an embodiment of the present invention.

5A through 5F are diagrams illustrating respective steps of a method of manufacturing the organic light emitting display device of FIG. 4.

<Brief description of symbols for the main parts of the drawings>

20,50: substrate 21,51: buffer layer

22,52: active layer 23,53: gate insulating film

24, 54: gate electrode 25, 55: interlayer insulating film

26,56: source electrode 27,57: drain electrode

58: passivation film 59: planarization film

60: pixel defining layer 61: first electrode layer

62: organic layer 63: second electrode layer

The present invention relates to an organic electroluminescent display and a method of manufacturing the same, and more particularly, to an organic electroluminescent display including a heat treatment process in a planarization film forming process and a method of manufacturing the same.

The organic electroluminescent device is a self-luminous display that emits light by electrically exciting a fluorescent organic compound and can be driven at low voltage, is easy to thin, and is pointed out as a problem in liquid crystal display such as wide viewing angle and fast response speed. It is attracting attention as the next generation display that can solve the problem.

The organic EL device includes a light emitting layer made of an organic material between the anode electrode and the cathode electrode. In the organic electroluminescent device, as the anode and cathode voltages are applied to these electrodes, holes injected from the anode are moved to the light emitting layer via the hole transport layer, and electrons are transferred from the cathode electrode to the light emitting layer via the electron transport layer. The electrons and holes recombine in the emission layer to generate excitons.

As the excitons change from the excited state to the ground state, the fluorescent molecules in the light emitting layer emit light to form an image. In the case of a full color organic electroluminescent device, a full color is realized by providing a pixel emitting three colors of red (R), green (G), and blue (B).

On the other hand, thin film transistors (hereinafter referred to as TFTs) used in flat panel display devices such as electroluminescent elements and liquid crystal displays are used as switching elements for controlling the operation of each pixel and as driving elements for driving the pixels. The thin film transistor has a semiconductor active layer having a drain region and a source region doped with a high concentration of impurities on a substrate, and a channel region formed between the drain region and the source region, the gate insulating film formed on the semiconductor active layer, and the channel of the active layer. It consists of a gate electrode formed on top of the region.

Meanwhile, a process of manufacturing an organic light emitting display device using an organic light emitting diode and a thin film transistor is as follows. First, a passivation film and a planarization film are formed on the thin film transistor, and the passivation film and the planarization film are patterned to form an opening. And a first electrode layer serving as an anode electrode of the organic electroluminescent element (OLED), a pixel definition film covering the first electrode layer, an organic layer formed in a predetermined opening of the pixel definition film and covering all pixels on the planarization film. The two-electrode layer is formed to form an organic electroluminescent element (OLED). Here, the thin film transistor and the first electrode layer are electrically connected to each other through an opening formed in the passivation film and the planarization film.

Here, the process of forming the planarization layer of the conventional organic light emitting display device is as follows. First, a passivation film and a planarization film are sequentially stacked on the thin film transistor. In detail, when the morphology of the indium tin oxide (ITO) used as the anode electrode in the organic light emitting diode (OLED) is not good, the leakage current increases and the dark spot becomes dark. Problems such as being formed may occur. Accordingly, a planarization film formed of acryl or the like is provided to improve morphology of an anode electrode such as indium tin oxide (ITO). Such a planarization film serves as an insulator and also serves as a mask for forming an opening of a lower passivation film. However, when the opening of the passivation film is formed using the planarization film as a mask, an undercut is formed in the lower part of the planarization film so that the deposition is not performed smoothly at the time of deposition of the anode electrode and the voids are formed. This can be

In order to remove such undercuts, conventionally, an ashing process using O ₂ is performed after etching of the passivation film to remove a portion of the planarization film in which the undercut has occurred.

However, the conventional flattening film manufacturing method has the following problems.

First, when removing the planarization film undercut (undercut) through the ashing process as in the prior art, there was a problem that the morphology of the surface of the planarization film worsens as the planarization film is ashed over the entire device. .

In addition, as the morphology of the planarization film surface is deteriorated in this manner, there is a problem in that the adhesion property between ITO (Indium Tin Oxide) used as an anode electrode and the planarization film is deteriorated.

In addition, due to excessive ashing of the planarization film, there is a problem that the diameter of the opening may be larger than the design value.

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic electroluminescent display device which removes undercuts formed in the planarization film through heat treatment in the process of forming the planarization film, and improves the morphology of the planarization film, and a method of manufacturing the same. do.

According to an aspect of the present invention, there is provided a semiconductor device, comprising: at least one thin film transistor having a semiconductor active layer, a gate electrode insulated from the semiconductor active layer, and a source and drain electrode respectively in contact with the semiconductor active layer; A passivation layer covering the thin film transistor and having a first opening exposing the source and drain electrodes; A planarization layer covering the passivation layer and having a second opening to expose the source and drain electrodes; And an organic light emitting element electrically connected to the thin film transistor through the first opening and the second opening, wherein the second opening is disposed above the first opening to cover an inner surface of the first opening. An organic light emitting display device is provided, wherein an edge of the organic light emitting diode is extended.

By such a structure, the undercut formed in the planarization film can be removed, and the morphology characteristic of the planarization film can be improved.

In the present invention, the planarization film may be formed to shield the passivation film.

In the present invention, the planarization layer may include an organic material.

In the present invention, the organic material may include any one selected from the group consisting of acryl, polyimide, and benzocyclobutene (BCB).

In the present invention, the passivation film may include an inorganic material.

In the present invention, the inorganic material may include any one of SiO ₂ and SiNx.

According to another aspect of the present invention, there is provided a method including: providing a thin film transistor; Forming a passivation film and a planarization film on the thin film transistor; Forming openings in the passivation film and the planarization film; Heat-treating the planarization film; And forming an organic light emitting diode electrically connected to the thin film transistor through the opening.

In the present invention, the heat treatment of the planarization film may include removing an undercut formed in the planarization film.

In the present invention, the heat treatment of the planarization film may include heat treating the planarization film to allow the planarization film to flow.

In the present disclosure, the heat treatment of the planarization layer may include shielding the passivation layer so that the opening of the passivation layer is not exposed to the outside.

In the present invention, the heat treatment of the planarization film may include forming an edge portion of the opening formed in the planarization film to cover sidewalls of the opening formed in the passivation film.

In the present invention, the heat treatment of the planarization film may include applying heat of 150 ° C. to 300 ° C. to the planarization film.

In the present invention, forming the openings in the passivation layer and the planarization layer may include patterning the planarization layer and etching the region of the passivation layer exposed by the patterning of the planarization layer.

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

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

Referring to FIG. 1, a thin film transistor (TFT) according to an embodiment of the present invention may be provided on the substrate 20. The substrate 20 may be a glass substrate or a plastic substrate.

A buffer layer 21 is formed on the substrate 20, an active layer 22 formed of a semiconductor material is provided on the buffer layer 21, and a gate insulating film 23 is formed to cover the active layer 22. A gate electrode 24 is formed on the gate insulating film 23, an interlayer insulating film 25 is formed to cover the gate electrode 24, and a source / drain electrode 26 ( 27) is formed. The source / drain electrodes 26 and 27 are in contact with the source / drain regions 22b and 22c of the active layer 22 by contact holes formed in the gate insulating film 23 and the interlayer insulating film 25, respectively.

The active layer 22 provided on the substrate 20 may be formed by being selected from an inorganic semiconductor or an organic semiconductor, and n-type or p-type impurities are doped in the source / drain regions 22b and 22c. The channel region 22a which connects these source region and drain region is provided.

The inorganic semiconductor forming the active layer 22 may include CdS, GaS, ZnS, CdSe, CaSe, ZnSe, CdTe, SiC, and Si.

The organic semiconductor forming the active layer 22 is a polymer, which may be polythiophene and its derivatives, polyparaphenylenevinylene and its derivatives, polyparaphenylene and its derivatives, polyfluorene and its derivatives, and polythiol. Offenvinylene 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, Oligothiophenes and alpha derivatives thereof of alpha-5-thiophene, phthalocyanine and derivatives thereof with or without metal, pyromellitic dianhydrides or pyromellitic diimides and derivatives thereof, perylenetetra Carboxylic acid dianhydrides or perylenetetracarboxylic diimides and derivatives thereof.

The active layer 22 is covered by the gate insulating film 23, and the gate electrode 24 is formed on the gate insulating film 23. The gate electrode 24 may be formed of a conductive metal film such as MoW, Al, Cr, Al / Cu, but is not limited thereto. Various conductive materials such as a conductive polymer may be used as the gate electrode 24. The gate electrode 24 is formed to cover a region corresponding to the channel region of the active layer 22.

2 is a plan view of an organic light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a pixel region 30 and a circuit region 40 are formed at the edge of the pixel region 30. The pixel area 30 includes a plurality of pixels, and each pixel includes a light emitting part that emits light to implement a predetermined image.

According to an embodiment of the present invention, the light emitting unit includes a plurality of sub-pixels each having an organic EL device. In the case of a full color organic light emitting display, subpixels of red (R), green (G), and blue (B) are arranged in various patterns such as lines, mosaics, and lattices to form pixels. It may be a mono color flat panel display instead of a display.

The circuit region 40 controls the image signal and the like input to the pixel region 30.

In the organic light emitting display device, at least one thin film transistor may be provided in the pixel region 30 and the circuit region 40, respectively.

The thin film transistor provided in the pixel region 30 includes a switching thin film transistor which transmits a data signal to the light emitting element according to the gate line signal and controls its operation, and a predetermined current is applied to the organic electroluminescent element according to the data signal. There is a pixel portion thin film transistor such as a driving thin film transistor to be driven to flow. In addition, the thin film transistor provided in the circuit region 40 includes a circuit part thin film transistor provided to implement a predetermined circuit.

Of course, the number and arrangement of the thin film transistors may vary depending on the characteristics of the display, the driving method, and the like, and the arrangement may also exist in various ways.

FIG. 3 is a cross-sectional view of a portion of the organic light emitting display device of FIG. 2.

As shown in Fig. 3, a buffer layer 51 is formed on a glass or plastic substrate 50, on which a thin film transistor (thin film transistor) and an organic electroluminescent element (OLED) are formed.

The active layer 52 of a predetermined pattern is provided on the buffer layer 51 of the substrate 50. The gate insulating layer 53 is provided on the active layer 52, and the gate electrode 54 is formed in a predetermined region above the gate insulating layer 53. The gate electrode 54 is connected to a gate line (not shown) for applying a thin film transistor on / off signal. An interlayer insulating layer 55 is formed on the gate electrode 54, and the source / drain electrodes 56 and 57 are respectively formed in the source / drain regions 52b and 52c of the active layer 52 through the contact holes. It is formed to be in contact. A passivation film 58 made of SiO ₂ , SiNx, or the like is formed on the source / drain electrodes 56 and 57, and acrylic, polyimide, and BCB are formed on the passivation film 58. The planarization film 59 is formed with organic substances, such as (Benzocyclobutene). A first electrode layer 61 serving as an anode of the organic light emitting diode OLED is formed on the planarization layer 59, and a pixel define layer 60 is formed of an organic material to cover the first electrode layer 61. After the predetermined opening is formed in the pixel definition film 60, the organic layer 62 is formed in the region defined by the opening. The organic layer 62 includes a light emitting layer. The present invention is not necessarily limited to such a structure, and the structures of various organic light emitting display devices may be applied as it is.

The organic light emitting diode OLED displays predetermined image information by emitting red, green, and blue light according to the flow of current, and is connected to the drain electrode 56 of the thin film transistor to receive positive power therefrom. The first electrode layer 61 and the second electrode layer 63 provided to cover all the pixels to supply negative power, and the organic layer disposed between the first electrode layer 61 and the second electrode layer 63 to emit light. It consists of 62.

The first electrode layer 61 and the second electrode layer 63 are insulated from each other by the organic layer 62, and light is emitted from the organic layer 62 by applying voltages having different polarities to the organic layer 62.

The organic layer 62 may be a low molecular or polymer organic layer. When the low molecular organic layer is used, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), and an electron may be used. An electron transport layer (ETL), an electron injection layer (EIL), and the like may be formed by stacking a single or a composite structure. The organic materials usable may also be copper phthalocyanine (CuPc), N, or the like. N-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (N, N'-Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine: NPB), Tris-8 It can be applied in various ways including tris-8-hydroxyquinoline aluminum (Alq3). These low molecular weight organic layers are formed by the vacuum deposition method.

In the case of the polymer organic layer, 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.

Such an organic layer is not necessarily limited thereto, and various embodiments may be applied.

Although the first electrode layer 61 functions as an anode electrode and the second electrode layer 63 functions as a cathode electrode, the polarities of the first electrode layer 61 and the second electrode layer 63 may be reversed. It's okay.

The first electrode layer 61 may be provided as a transparent electrode or a reflective electrode, and when used as a transparent electrode, may be formed of ITO, IZO, ZnO, or In ₂ O ₃ , and when used as a reflective electrode, Ag, After forming a reflecting film with Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, a compound thereof, or the like, ITO, IZO, ZnO, or In ₂ O ₃ can be formed thereon.

Meanwhile, the second electrode layer 63 may also be provided as a transparent electrode or a reflective electrode. When the second electrode layer 63 is used as the transparent electrode, the second electrode layer 63 is used as the cathode electrode, and thus, a metal having a small work function, that is, Li and Ca , LiF / Ca, LiF / Al, Al, Ag, Mg, and a compound thereof are deposited to face the organic layer 62, and thereafter, a transparent electrode such as ITO, IZO, ZnO, or In ₂ O ₃ is deposited thereon. The auxiliary electrode layer or the bus electrode line may be formed of the forming material. When used as a reflective electrode, Li, Ca, LiF / Ca, LiF / Al, Al, Ag, Mg, and compounds thereof are formed by depositing the entire surface.

4 is a flowchart illustrating a method of manufacturing an organic light emitting display device according to an exemplary embodiment of the present invention, and FIGS. 5A to 5F illustrate respective steps of performing the method of manufacturing the organic light emitting display device of FIG. 4. admit.

4 and 5, the method of manufacturing an organic light emitting display device according to an exemplary embodiment of the present invention includes forming a thin film transistor (S110), and forming a passivation film and a planarization film on the thin film transistor. And forming openings in the passivation film and the planarization film (step S130), heat treating the planarization film (step S140), and electrically forming the openings through the patterned openings. Forming an organic light emitting device connected to (S150 step).

5A is a diagram illustrating a step of forming a thin film transistor (TFT) on a substrate (step S110). The formation process of the thin film transistor is as described above with reference to FIG. 1.

5B is a diagram illustrating a step of forming a passivation film and a planarization film on a thin film transistor (step S120). Referring to FIG. 5B, a passivation film 58 made of inorganic materials such as SiO ₂ and SiNx is formed on the source / drain electrodes 56 and 57. The planarization layer 59 is formed on the passivation layer 58 by an organic material such as acryl, polyimide, and benzocyclobutene (BCB). The passivation film 58 and the planarization film 59 are deposited by a method such as chemical vapor deposition (CVD), plasma enhanced (CVD), low pressure (LP) CVD, and electron cyclotron resonance (ECR) CVD. Can be.

5C and 5D illustrate an operation of forming openings in the passivation film and the planarization film (step S130).

First, as shown in FIG. 5C, the planarization film 59 is patterned to form a predetermined first opening 59a. Next, as illustrated in FIG. 5D, the passivation film 58 region below the first opening 59a is etched using the planarization film 59 as a mask to form a second opening 58a. . At this time, the width of the etched second opening is formed to be wider than the width of the first opening, that is, an undercut 59b occurs. This undercut may cause the voids to be formed without the deposition being smoothly performed during the deposition of the anode electrode. Therefore, a predetermined heat treatment process is performed on the planarization film 59 to remove the undercut 59b.

5E is a diagram illustrating a step (S140) of heat treatment of the planarization film. Referring to FIG. 5E, the undercut 59b is removed by applying a predetermined heat to the planarization film 59 using the flowing characteristic of the planarization film 59 formed of acryl, which is an organic material.

In the conventional method of manufacturing an organic light emitting display device, in order to remove undercuts, an ashing process using O ₂ is performed after etching of the passivation layer to remove portions of the planarization layer where the undercut has occurred. It was. However, when the planarization film undercut is removed through the ashing process as described above, there is a problem that the morphology of the planarization film surface deteriorates as the planarization film is ashed over the entire device. In addition, as the morphology of the planarization film surface is deteriorated, there is a problem that the adhesion property between ITO (Indium Tin Oxide) used as an anode electrode and the planarization film is deteriorated. In addition, due to excessive ashing of the planarization film, there is a problem that the diameter of the opening may be larger than the design value.

Therefore, in order to solve the problem, the present invention is characterized in that the undercut 59b is removed by applying a predetermined heat to the planarization film 59 after etching the passivation film 58.

That is, in the present invention, the planarization film 59 is heat-treated to remove the undercut 59b formed after the passivation film 58 is etched. The heat treatment may be performed by applying heat of approximately 150 ° C to 300 ° C to the planarization film 59. When such heat is applied to the planarization film 59, the planarization film 59 having a flowing characteristic formed of acryl, which is an organic substance, flows downward. As the flattening film 59 which protrudes in this way and forms the undercut 59b flows downward, the undercut 59b can be removed. In addition, the planarization film 59 flowing down toward the lower passivation film 58 covers the opening 58a of the passivation film 58, so that the opening 58a of the passivation film 58 is not exposed to the outside. It may be.

FIG. 5F is a diagram illustrating a step (S150) of forming an organic light emitting diode electrically connected to a thin film transistor through a patterned opening. The formation process of the organic light emitting device is as described above with reference to FIG. 3.

With such a configuration, it is possible to obtain an effect of removing undercuts formed in the planarization film during the planarization film formation process through heat treatment. In addition, by removing the undercut in this manner, it is possible to obtain an effect of improving the morphology characteristic of the planarization film. In addition, as the morphology characteristic of the planarization layer is improved in this way, an effect of improving adhesion characteristics between indium tin oxide (ITO) and the planarization layer used as an anode electrode can be obtained. In addition, as the morphology characteristic of the planarization film is improved, an effect of preventing dark spots may be obtained. Moreover, the effect which can maintain the diameter of the opening part formed in a planarization film and a passivation film to a desired standard is obtained.

According to the present invention, the undercut formed in the planarization film can be removed, and the effect of improving the morphology characteristic of the planarization film can be obtained.

Although the present invention has been described with reference to the embodiments shown in the 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. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (13)

At least one thin film transistor formed on a substrate and having a semiconductor active layer, a gate electrode insulated from the semiconductor active layer, and a source and a drain electrode respectively in contact with the semiconductor active layer; A passivation layer covering the thin film transistor and having a first opening exposing the source and drain electrodes; A planarization layer covering the passivation layer and having a second opening to expose the source and drain electrodes; And And an organic light emitting diode electrically connected to the thin film transistor through the first opening and the second opening. And an edge of the second opening disposed above the first opening so as to cover an inner surface of the first opening. The method of claim 1, And the planarization layer is formed to shield the passivation layer. The method of claim 1, The flattening layer includes an organic material. The method of claim 3, wherein The organic material includes an organic light emitting display device including any one selected from the group consisting of acryl, polyimide, and benzocyclobutene (BCB). The method of claim 1, The passivation layer includes an organic light emitting display device. The method of claim 5, wherein The inorganic material includes any one of SiO ₂ and SiNx. Providing a thin film transistor; Forming a passivation film and a planarization film on the thin film transistor; Forming openings in the passivation film and the planarization film; Heat-treating the planarization film; And And forming an organic light emitting element electrically connected to the thin film transistor through the opening. The method of claim 7, wherein The heat treatment of the planarization film may include And removing an undercut formed in the planarization layer. The method of claim 7, wherein The heat treatment of the planarization film may include And heat treating the planarization layer to allow the planarization layer to flow. The method of claim 7, wherein The heat treatment of the planarization film may include And shielding the passivation layer so that the opening of the passivation layer is not exposed to the outside. The method of claim 7, wherein The heat treatment of the planarization film may include And forming an edge portion of the opening formed in the planarization film to cover the sidewall of the opening formed in the passivation film. The method of claim 7, wherein The heat treatment of the planarization film may include And applying heat of 150 ° C to 300 ° C to the planarization layer. The method of claim 7, wherein Forming an opening in the passivation film and the planarization film, Patterning the planarization film; And etching an area of the passivation layer exposed by patterning the planarization layer.

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