KR100390680B1 - Active-Matrix Organic Electroluminescent Device and Method for Fabricating the same - Google Patents

Abstract

In the present invention, the insulating substrate; A semiconductor layer and a capacitor electrode made of polysilicon (p-Si) formed on the insulating substrate; A gate electrode formed at a central portion of the semiconductor layer; A first insulating layer formed on the gate electrode and the capacitor electrode; A power electrode formed at a position corresponding to the capacitor electrode on the first insulating layer; An anode electrode formed in a pixel unit on the first insulating layer on which the power electrode is formed and made of a transparent conductive material; A second insulating layer positioned on the anode and having a first anode exposed portion exposing a portion of the anode; A drain electrode formed to be connected to the anode and a source electrode spaced apart from the drain electrode at a predetermined interval and connected to the power electrode through the first anode exposed portion of the second insulating layer; A third insulating layer disposed on the source and drain electrodes and having a second anode exposed portion formed at a position corresponding to the first anode exposed portion of the second insulating layer; An organic electroluminescent layer connected to the anode through the second anode exposed portion and formed at a position corresponding to the anode; By providing an active matrix type organic electroluminescent device including a cathode (cathode electrode) formed of an opaque metal formed on the upper surface in contact with the organic electroluminescent layer, since the number of mask process can be reduced, manufacturing cost and process time can be reduced In addition, the present invention has an advantage of providing an active matrix organic light emitting display device having an improved production yield.

Description

Active-Matrix Organic Electroluminescent Device and Method for Fabricating the same

The present invention relates to an organic electroluminescent device, and more particularly to an active-matrix organic electroluminescent device.

Recently, a liquid crystal display (LCD) has a light weight and low power consumption, and is currently used as a flat panel display (FPD).

However, the liquid crystal display is not a light emitting device but a light receiving device, and since there are technical limitations in brightness, contrast, viewing angle, and large area, efforts to develop a new flat panel display that can overcome these disadvantages are actively developed. It is becoming.

One of the new flat panel displays, the organic light emitting display device is self-luminous, and thus has a better viewing angle and contrast ratio than a liquid crystal display device. In addition, since it is possible to drive DC low voltage, fast response speed, and all solid, it is strong against external shock, wide use temperature range, and especially inexpensive in manufacturing cost.

In particular, since the organic light emitting device has a very simple process unlike a liquid crystal display device or a plasma display panel (PDP), deposition and encapsulation equipment are all.

On the other hand, a passive matrix (passive matrix) that does not have a separate thin film transistor has been mainly used as a driving method of the organic light emitting device.

However, since the passive matrix method has many limitations such as resolution, power consumption, and lifespan, active matrix organic electroluminescent devices for the manufacture of next-generation displays requiring high resolution and large screens have been researched and developed.

In the passive matrix method, a scan line and a signal line cross each other to form a device in a matrix form, whereas in an active matrix method, a thin film transistor that opens and closes each pixel is a pixel. The thin film transistors are placed on each side, and the thin film transistor serves as a switch, so that the first electrode is turned on / off in units of pixels, and the second electrode facing the first electrode is used as a common electrode.

Since the passive matrix method sequentially drives the scan lines according to time to drive each pixel, in order to indicate the required average luminance, the instant matrix should be instantaneous as much as the average luminance multiplied by the number of lines.

Therefore, the more lines, the higher voltage and more current must be applied instantaneously, which accelerates the deterioration of the device and the higher power consumption, which is not suitable for high resolution and large area display.

On the other hand, in the active matrix method, a voltage applied to a pixel is charged in a storage capacitor (C _ST ), and the power is applied until the next frame signal is applied, thereby irrespective of the number of scan lines. Run continuously for one screen.

Therefore, in the active matrix system, since the same luminance is displayed even when a low current is applied, low power consumption, high definition, and large size can be obtained.

Hereinafter, the basic structure and operation characteristics of the active matrix organic electroluminescent device will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a basic pixel structure of a general active matrix organic light emitting display device.

As shown, a scan line is formed in a first direction, is formed in a second direction crossing the first direction, and is a signal line and a power supply line spaced apart from each other by a predetermined distance. ) Is formed to define one pixel area.

Capacitor lines are formed in the pixel region in the first direction.

A switching TFT, which is an addressing element, is formed at an intersection point of the scan line and the signal line, and is connected to the switching TFT and the capacitor line to form a storage capacitor, and the switching thin film transistor and storage A driving thin film transistor, which is a current source element, is formed in connection with the connection portion of the capacitor and the power supply line, and an anode electrode is connected to the driving thin film transistor, and the anode is formed of a constant current driving method. It is connected to a cathode through an electroluminescent diode.

An anode and a cathode connected by the organic light emitting diode constitute an organic light emitting device.

The switching thin film transistor controls a voltage and stores a current source.

Hereinafter, the driving principle of the active matrix organic light emitting display device will be described.

In the active matrix method, when a signal is applied to a corresponding electrode according to a selection signal, the gate of the switching thin film transistor is turned on, and the data signal passes through the gate of the switching thin film transistor and is applied to the driving thin film transistor and the storage capacitor. When the gate of the driving thin film transistor is turned on, current from the power supply line is applied to the organic light emitting layer through the gate of the driving thin film transistor to emit light.

At this time, the degree of opening and closing of the gate of the driving thin film transistor is changed according to the magnitude of the data signal, so that gray scale display can be performed by adjusting the amount of current flowing through the driving thin film transistor.

In the non-selection period, data charged in the storage capacitor is continuously applied to the driving thin film transistor, so that the organic light emitting diode can emit light continuously until the next screen signal is applied.

Due to this principle, the active matrix type organic light emitting display device may apply a lower voltage and instantaneously lower current than the passive matrix method, and the organic light emitting display device can be driven continuously for one screen time regardless of the number of selected lines. It is advantageous for low power consumption, high resolution and large area. On the other hand, since the current flows through the thin film transistor, the conventional amorphous silicon (a-Si) thin film transistor is difficult to employ because of its low electric field effect mobility due to the amorphous silicon particles of amorphous silicon. Therefore, polysilicon (p-Si) thin film transistors having uniform grains and excellent field effect mobility are required.

Since the polysilicon thin film transistor has a large field effect mobility, a driving circuit can be made on the substrate. If the polysilicon thin film transistor is used to make the driving circuit directly on the substrate, the driving IC cost can be reduced and the mounting is simplified.

As a method of manufacturing this polysilicon, the low-temperature crystallization through laser annealing using amorphous silicon is mainly used.

FIG. 2 is a cross-sectional view corresponding to a partial region including one thin film transistor of a conventional active matrix type organic light emitting diode, and FIG. 1 illustrates a driving thin film transistor connected to an anode and a storage capacitor of the organic light emitting diode. Explain.

As illustrated, a thin film transistor T composed of the semiconductor layer 32, the gate electrode 38, the source and drain electrodes 50 and 52 is formed on the insulating substrate 1, and the source electrode ( 50 is connected to a power electrode 42 formed in a power supply line (not shown), and an anode 58 made of a transparent conductive material is connected to the drain electrode 52.

A capacitor electrode 34 made of the same material as that of the semiconductor layer 32 is formed in an insulated lower portion of the lower portion corresponding to the power electrode 42. The power electrode 42 and the capacitor electrode 34 are formed by the power electrode 42 and the capacitor electrode 34. The storage capacitor C _ST is formed.

In addition, the organic light emitting layer 64 and the cathode 66 made of an opaque metal material are sequentially stacked on the anode 58 to form the organic light emitting unit E. FIG.

Looking at the stacked structure of the insulating layers positioned in the organic light emitting unit (E), the buffer layer 30 and the storage capacitor (C _ST ) to buffer the insulating substrate 1 and the semiconductor layer 32. The first protective layer 40, the second protective layer 44 between the drain electrode 52 and the power electrode 42, and the third between the anode 58 and the source electrode 50 The protective layer 54 and the fourth protective layer 60 between the thin film transistor T and the anode 58 are sequentially stacked, and the first to fourth protective layers 40, 44, and 54 are stacked. 60 includes contact holes (not shown) for electrical connection between the respective layers.

3A to 3I are cross-sectional views illustrating a manufacturing process of the active matrix type organic light emitting display device of FIG. 2, respectively. Each pattern in the manufacturing process includes a pattern drawn on a separate mask on a substrate on which a thin film is deposited. It is formed through a series of processes that are transferred to and formed on the substrate, and this process refers to a photolithography process in which photoresist coating, alignment exposure, and development are the main processes. do.

Hereinafter, the photolithography process will be described as a mask process in order to describe the number of masks produced in stages.

In FIG. 3A, a buffer layer 30 is formed on the insulating substrate 1 using the first insulating material over the entire surface of the substrate, and the polysilicon is used on the buffer layer 30, and is active by the first mask process. Layer 32a and capacitor electrode 34 are formed.

Next, in FIG. 3B, a second insulating material and a first metal are successively deposited on the substrate having passed through the step of FIG. 3A, and then gate insulating films are respectively formed in the center of the active layer 32a by a second mask process. 36 and the gate electrode 38.

In FIG. 3C, a first protective layer 40 made of a third insulating material is formed on the substrate having passed through FIG. 3B, and a second metal is deposited on the first protective layer 40. The power electrode 42 is formed at a position covering the capacitor electrode 34 by a three mask process.

In FIG. 3D, after depositing a third insulating material on the substrate having passed through the step of FIG. 3C, the both ends of the active layer 32a and a part of the power electrode 42 are exposed by a fourth mask process. The second protective layer 44 having the first and second ohmic contact holes 46a and 46b and the capacitor contact hole 48 is formed.

Both ends of the active layer 32a form a drain region Ia and a right portion form a source region Ib so as to be connected to source and drain electrodes to be formed in a later process.

In this step, the exposed both ends of the active layer 32a are ion-doped, and the ion-doped portion is formed of an ohmic contact layer 32b containing impurities to form the active layer 32a. ) And the ohmic contact layer 32b are completed.

Next, in step 3e, after depositing the third metal, the power electrode 42 is formed through the capacitor contact hole (48 in FIG. 3D) and the first ohmic contact hole (46a in FIG. 3D) by a fifth mask process. ) And a source electrode 50 connected to the ohmic contact layer 32b of the source region Ib, and spaced apart from the source electrode 50 at a predetermined interval, and drained through the second ohmic contact hole 46b of FIG. 3D. A drain electrode 52 connected to the ohmic contact layer 32b of the region Ia is formed.

In this step, the thin film transistor T including the semiconductor layer 32, the gate electrode 38, the source and drain electrodes 50 and 52 is completed.

On the other hand, the power electrode 42 and the capacitor electrode 34 are electrically connected to the source electrode 52 and the capacitor line (not shown) (Fig. 1), respectively, the first protective layer 40 as an insulator, the storage capacitor (C _ST ) is formed.

In FIG. 3F, after depositing a fourth insulating material on the substrate having passed through FIG. 3E, a third protective layer 54 having a drain contact hole 56 is formed by a sixth mask process.

Next, in step 3g, an organic field, which is an organic light emitting layer region, is formed by a seventh mask process using a fourth metal so as to be connected to the drain electrode 50 through the drain contact hole 56 in FIG. 3f. The anode 58 is formed in the light emitting portion E.

In FIG. 3H, after the fifth insulating material is deposited on the substrate having undergone the 3g step, the anode exposed portion 62 exposing the anode 58 corresponding to the organic light emitting portion E by the eighth mask process. To form a fourth protective layer 60.

The fourth protective layer 60 serves to protect the thin film transistor T from moisture and foreign matter.

As a result, the manufacturing process accompanied by the mask process is completed, and in step 3i, the organic electroluminescent layer 64 connected to the anode 58 through the anode exposed portion 62 of FIG. 3h and the organic electroluminescent layer ( 64) A cathode 66 is formed over the entire surface of the substrate using a fifth metal on the top.

As the fifth metal, in order to reflect the light emitted from the organic electroluminescent layer 64 to the anode 58 to realize the screen of the organic electroluminescent device, it has a reflection characteristic and a work function to easily display electrons. Select a metal material with a low work function value.

That is, at least eight mask processes are required in the conventional active matrix organic electroluminescent device.

The mask process includes a high temperature process according to the deposition of the corresponding material and a process of applying physical or chemical treatment on the substrate, such as a relatively expensive photoresist requirement and etching process, so that the number of mask processes is reduced and thus the production yield is increased. Providing this improved product is a problem of the active matrix organic electroluminescent device at present.

In order to solve this problem, the present invention is to provide an active matrix organic electroluminescent device having improved manufacturing cost and production yield by reducing the number of mask process by the method of reducing the contact hole forming process formed in each insulating layer. do.

To this end, in the present invention, the process of forming the anode of the organic light emitting device is performed after the protective layer forming process covering the upper portion of the gate electrode, and the anode exposed portion is formed in a process of forming the ohmic contact hole and the capacitor contact hole later. By performing the process in one mask process, the mask process required to connect the existing drain electrode and the anode can be omitted.

1 is a view showing a basic pixel structure of a general active matrix organic electroluminescent device.

2 is a cross-sectional view corresponding to a partial region including one thin film transistor of a conventional active matrix organic electroluminescent device.

3A to 3I are cross-sectional views each showing a manufacturing process of the active matrix organic electroluminescent device of FIG.

4 is a cross-sectional view corresponding to a partial region including one thin film transistor of an active matrix organic electroluminescent device according to the present invention;

5A to 5H are cross-sectional views illustrating respective steps of a manufacturing process of the active matrix organic electroluminescent device of FIG. 4.

<Explanation of symbols for main parts of drawing>

100: insulating substrate 102: buffer layer

104 semiconductor layer 107 gate insulating film

108: gate electrode 110: first protective layer

112: power electrode 114: anode

118: second protective layer 124: source electrode

126: drain electrode 128: third protective layer

132: organic light emitting layer 134: cathode

In order to solve the above object, one feature of the present invention includes a plurality of first lines formed in a first direction, a plurality of second lines formed in a second direction crossing the first direction, and defining a pixel area; An active matrix organic electroluminescent device comprising a thin film transistor having a semiconductor layer, a gate electrode, a source electrode, and a drain electrode, formed at intersection points of the first and second lines, and opening and closing each pixel; An insulation substrate; A semiconductor layer and a capacitor electrode made of polysilicon (p-Si) formed on the insulating substrate; A gate electrode formed at a central portion of the semiconductor layer; A first insulating layer formed on the gate electrode and the capacitor electrode; A power electrode formed at a position corresponding to the capacitor electrode on the first insulating layer; An anode electrode formed in a pixel unit on the first insulating layer on which the power electrode is formed and made of a transparent conductive material; A second insulating layer positioned on the anode and having a first anode exposed portion exposing a portion of the anode; A drain electrode formed to be connected to the anode and a source electrode spaced apart from the drain electrode at a predetermined interval and connected to the power electrode through the first anode exposed portion of the second insulating layer; A third insulating layer disposed on the source and drain electrodes and having a second anode exposed portion formed at a position corresponding to the first anode exposed portion of the second insulating layer; An organic electroluminescent layer connected to the anode through the second anode exposed portion and formed at a position corresponding to the anode; Provided is an active matrix organic electroluminescent device comprising a cathode (cathode electrode) made of an opaque metal formed in contact with the organic electroluminescent layer.

It is preferable to use an inorganic insulating material for the first to third insulating layers, and more preferably, any one of silicon oxide film (Si0 ₂ ) and silicon nitride film (Si ₃ N ₄ ) of the inorganic insulating material.

In addition, both ends of the semiconductor layer form an ion doped ohmic contact layer, and the second insulating layer includes first and second ohmic contact holes and a capacitor exposing portions of the ohmic contact layer and the power electrode at both ends of the semiconductor layer, respectively. It further comprises a contact hole.

The source and drain electrodes are connected to the ohmic contact layers at both ends of the semiconductor layer through the first and second ohmic contact holes, respectively.

The source electrode is connected to the power electrode through the capacitor contact hole.

In addition, the transparent conductive material forming the anode is preferably made of indium tin oxide (ITO), and the opaque metal forming the cathode is preferably made of a metal having a work function of less than 4 eV.

The opaque metal may be an alkali metal, or one of a composite layer made of magnesium / silver alloy (Mg: Ag), aluminum / lithium alloy (Al: Li), lithium fluoride (LiF), and aluminum. .

The first line is a scan line including a gate electrode and a capacitor line spaced apart from the scan line, and is a capacitor line including the capacitor electrode, and the second line is a signal line including a source electrode and a predetermined distance from the signal line. It is formed to be, characterized in that the power supply line including the power electrode.

A switching thin film transistor is formed at the intersection of the scan line and the signal line, and a storage capacitor is connected to the switching thin film transistor and the capacitor line, and a driving thin film transistor is formed to be connected to the storage capacitor and the power supply line. The anode, the organic light emitting diode, and the cathode are connected to the driving thin film transistor.

The organic light emitting layer is a multilayer film including a hole-injection layer, a hole-transport layer, an emissive layer, and an electron-transport layer in order between the anode and the cathode. It is characterized by that.

The active matrix organic electroluminescent device is characterized by being formed by vacuum evaporation (vacuum evaporation).

In still another aspect of the present invention, there is provided a method of forming a plurality of first lines in a first direction, and forming a plurality of second lines arranged in a second direction crossing the first direction to define a pixel area. And opening and closing each pixel at an intersection point of the first and second lines, and forming a thin film transistor having a semiconductor layer, a gate electrode, a source, and a drain electrode (Active-Matrix). An organic electroluminescent device) comprising the steps of: providing an insulating substrate; Forming a semiconductor layer and a capacitor electrode on the insulating substrate using polysilicon; Forming a gate electrode at a central portion of the semiconductor layer; Forming a first insulating layer on the gate electrode; Forming a power electrode at a position corresponding to the capacitor electrode on the first insulating layer; Forming an anode using a transparent conductive material on the substrate on which the power electrode is formed; Forming a second insulating layer having a first anode exposed portion for exposing a portion of the anode; Forming a drain electrode connected to the anode and a source electrode spaced apart from the drain electrode by a first anode exposed portion of the second insulating layer, the source electrode being connected to the power electrode; Forming a third insulating layer on the source and drain electrodes, the third insulating layer having a second anode exposed portion at a position corresponding to the first anode exposed portion; Providing a method of manufacturing an active matrix organic electroluminescent device comprising the step of forming a cathode made of an opaque metal on the organic light emitting layer connected to the anode and the organic electroluminescent layer connected to the anode through the second anode exposed portion. do.

In the forming of the first anode contact hole in the second insulating layer, contact holes exposing both ends of the semiconductor layer and a part of the power electrode are formed.

The method may further include forming an ohmic contact layer in which impurities are implanted by ion doping the both ends of the semiconductor layer.

The source and drain electrodes may be connected to the ohmic contact layers at both ends of the semiconductor layer through corresponding contact holes formed in the second insulating layer.

The source electrode is connected to the power electrode through a contact hole of the second insulating layer partially exposing the power electrode.

The active matrix organic electroluminescent device is characterized by being formed by a vacuum deposition method.

The transparent conductive material is ITO, and the opaque metal is a metal having a work function of less than 4 eV.

The organic light emitting layer is a multilayer film including a hole-injection layer, a hole-transport layer, an emissive layer, and an electron-transport layer in order between the anode and the cathode. It is characterized by that.

The forming of the first line may include forming a scan line including the gate electrode and a capacitor line spaced apart from the scan line by a predetermined distance, and forming a capacitor line including the capacitor electrode. The method may include forming a signal line including the source electrode and a power supply line spaced apart from the signal line by a predetermined distance and including the power electrode.

The first to third insulating layers are made of an inorganic insulating material.

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

4 is a cross-sectional view corresponding to a partial region including one thin film transistor of an active matrix type organic light emitting display device according to the present invention. Since the semiconductor layer is formed using polysilicon, a gate electrode is formed on the semiconductor layer. A top gate type thin film transistor structure will be described as an example.

In the present invention, the basic pixel structure of FIG. 1 may be applied, but in addition, a thin film transistor is formed at the intersection of the scan line and the signal line, and is connected to the thin film transistor to form an organic light emitting display device. In order to improve the luminance uniformity, a method of configuring four thin film transistors by adding a compensation thin film transistor may also be applied.

As shown, a buffer layer 102 is formed on the transparent insulating substrate 1, and a semiconductor layer 104 and a capacitor electrode 106 are formed independently on the buffer layer 102, respectively. The gate insulating film 107 and the gate electrode 108 are formed in the center part of the layer 104 in order, and are connected to the both ends of this semiconductor layer 104, and the source and drain electrodes 124 and 126 are formed.

The power electrode 112 is formed at a position connected to the source electrode 124 and covering the capacitor electrode 106 in an insulated state by the first protective layer 110.

The power electrode 112 and the capacitor electrode 106 having the first protective layer 110 interposed therebetween constitute a storage capacitor C _ST .

In addition, an anode 114 is formed in the organic light emitting unit E, which is connected to the drain electrode 126 and configured in a pixel unit.

The anode 114 is formed on the anode 114 through the anode exposed portion 130 formed in the second protection layer 118 while insulated from the thin film transistor T by the second protection layer 118. The organic light emitting layer 132 is connected to each other.

In addition, a cathode 134 serving as a common electrode is formed at an upper portion in contact with the organic light emitting layer 132.

Looking at the stacked structure of the organic light emitting unit (E), the first protective layer 110 is formed on the buffer layer 102, the anode 114 is formed on the first protective layer 110 is formed Second and third protective layers 118 and 128 having the anode exposed portion 130 in common are formed on the anode 114 in this order, and the anode 114 is formed through the anode exposed portion 130. In connection with the organic light emitting layer 132, the cathode 134 is formed.

In this case, the anode 114 is connected to the drain electrode 126 of the thin film transistor T through the anode exposed portion 130, and the organic light emitting layer 132 is thin film by the third protective layer 128. Insulated from the transistor T, the anode is connected to the anode 114 through the anode exposed portion 130.

That is, in the active matrix type organic electroluminescent device according to the present invention, the anode 114 is formed on the first protective layer 110 so that the drain electrode 126 is in contact with the anode 114, and thus the anode is formed. Since the contact hole process required for the contact between the 114 and the drain electrode 126 is simultaneously performed in another contact hole (for example, an ohmic contact hole and a capacitor contact hole), a separate contact hole process can be omitted. The number of mask processes can be reduced.

Hereinafter, a method of manufacturing an active matrix organic light emitting display device according to the present invention will be described in detail with reference to the accompanying drawings.

5A to 5H are cross-sectional views each showing a manufacturing process of the active matrix organic electroluminescent device of FIG. 4 step by step.

All materials used in the organic electroluminescent device according to the present invention should be capable of vacuum deposition. It is also assumed that it has high thermal stability at glass transition and pyrolysis temperatures.

In FIG. 5A, a buffer layer 102 made of a first insulating material is formed on the transparent insulating substrate 100, and the active layer 104a is formed by using a polysilicon on the buffer layer 102 by a first mask process. And capacitor electrodes 106 are formed, respectively.

The translucent insulating substrate 100 is preferably made of any one of a glass substrate, a plastic substrate, and a flexible substrate.

In the process of forming the active layer 104a using the polysilicon, the process of depositing amorphous silicon on the buffer layer 102 and then crystallizing the polysilicon by heat treatment after dehydrogenation of the amorphous silicon layer is performed. Include.

However, the crystallization process may be performed at any stage before or after the first mask process.

In this case, the buffer layer 102 serves to prevent damage from being applied to the insulating substrate 100 during the polysilicon crystallization process, and the first insulating material constituting the buffer layer 102 is contacted. It is preferable to use an inorganic insulating material that is easy to have characteristics and deposition processes, and more preferably, to silicon oxide film (Si0 ₂ ) and silicon nitride film (Si ₃ N ₄ ).

Although not shown in the drawings, a process of forming a capacitor line (see FIG. 1) including the capacitor electrode 106 in a first direction is included.

In FIG. 5B, the second insulating material and the first metal layer are sequentially deposited on the substrate having passed through the step of FIG. 5A, and then the second insulation is formed in the center of the active layer 104a by a second mask process. A material is formed of the gate insulating film 107, and the first metal layer is formed of the gate electrode 108 using the gate insulating film 107 as a lower layer.

The second insulating material may be the same material as that of the first insulating material in FIG. 3A. Preferably, the second insulating material is one of a silicon oxide film (Si0 ₂ ) and a silicon nitride film (Si ₃ N ₄ ).

The first metal layer is preferably a double metal layer having aluminum or an aluminum alloy as a lower layer, and a metal having a high chemical corrosion resistance such as molybdenum (Mo), nickel (Ni), tungsten (W) as an upper layer, More preferably, a double metal layer having aluminum neodymium (AlNd) / molybdenum (Mo) as the lower and upper layers, respectively.

In this step, although not shown in the drawings, a process of forming a scan line including the gate electrode 108 spaced apart by a predetermined distance in the same direction as the capacitor line described above with reference to FIG. 5A is included.

In FIG. 5C, after forming the first passivation layer 110 with the third insulating material on the substrate having passed through FIG. 5B, the second metal layer is deposited on the first passivation layer 110, and then The power electrode 112 is formed at a position covering the capacitor electrode 106 in a mask process.

The power electrode 112 and the capacitor electrode 106 corresponding to each other with the first protective layer 110 interposed therebetween constitute a storage capacitor C _ST .

The third insulating material may be the same material as the second insulating material used in FIG. 5B, but since the third insulating material serves as an insulator constituting the storage capacitor C _ST , an insulating material having a low dielectric constant is more preferable. Do.

The second metal layer is preferably a low resistance metal material, and more preferably a double metal layer having a metal material including aluminum or a metal material containing aluminum as a lower metal layer.

In this step, although not shown in the drawings, a process of forming a power supply line including the power electrode 112 in a second direction intersecting the above-described scan line and capacitor line is included.

In FIG. 5D, after depositing the third metal on the substrate having passed through FIG. 5C, the anode 114 is formed by a fourth mask process.

The anode 114 is an organic electroluminescent unit E capable of transmitting light in the organic electroluminescent layer (not shown) in the pixel region which can be defined as the region where the scan line and the power supply line described with reference to FIG. 5C intersect. To form.

The third metal is preferably a transparent conductive material, more preferably ITO (Indium Tin Oxide).

In FIG. 5E, the anode 114, the both ends of the active layer 104a, and a portion of the power electrode 112 are respectively formed by a fifth mask process using a third insulating material on the substrate having passed through FIG. 5D. A second protective layer 118 having the first anode exposed portion 116, the first and second ohmic contact holes 120a and 120b and the capacitor contact hole 122 to be exposed is formed.

In this step, an ion doping treatment is performed on the substrate on which the second protective layer 118 is formed, and both ends of the exposed active layer 104a are formed of an ohmic contact layer 104b implanted with impurities. The semiconductor layer 104 including the active layer 104a and the ohmic contact layer 104b is completed.

In the ion doping process, depending on the implanted ions (n ⁺ , p ⁺ ), it can be classified as n-type or p-type, which is irrelevant in the present invention.

The ohmic contact layer 104b formed after the ion doping has the source and drain regions IIa and IIb, respectively, which are in contact with the source and drain electrodes in a later process.

The mask process for forming each contact hole is preferably formed by dry etching in a chamber having a predetermined condition.

In FIG. 5F, after the fourth metal is deposited on the substrate having passed through FIG. 5E, source and drain electrodes 124 and 126 are formed by a sixth mask process.

At this time, the source electrode 124 is connected to the ohmic contact layer 104b and the power electrode 112 of the source region IIa through the first ohmic contact hole 120a in FIG. 5E and the capacitor contact hole 122 in FIG. 5E. And the drain electrode 126 is formed through the second ohmic contact hole 120b of FIG. 5E and the first anode exposed portion 116, and the ohmic contact layer 104b and the anode of the drain region IIb. 114).

Although not shown in the drawings, the step further includes a step of forming a signal line including a source electrode of the switching thin film transistor (FIG. 1) in a parallel direction and spaced apart from the power supply line.

The fourth metal is preferably a double metal layer composed of aluminum neodymium / molybdenum or one of molybdenum, nickel, and tungsten, like the metal material constituting the gate electrode.

In this step, the thin film transistor T including the semiconductor layer 104, the gate electrode 108, the source and drain electrodes 124 and 126 is completed.

Although not shown in the drawings, this step may include a process of forming at least one thin film transistor (T) in addition to the thin film transistor (T).

In FIG. 5G, after depositing a fourth insulating material on the substrate having passed through FIG. 5F, the second anode is exposed to a position corresponding to the first anode exposed portion 116 of FIG. 5F by a seventh mask process. The third protective layer 128 having the portion 130 is formed.

The third passivation layer 128 is formed to protect the thin film transistor T element and to insulate the thin film transistor T from the organic light emitting layer to be formed later.

The fourth insulating material is preferably an inorganic insulating material, and more preferably one of a silicon nitride film or a silicon oxide film.

As described above, in the manufacturing process of the active matrix organic electroluminescent device according to the present invention, since seven mask processes are performed, the number of mask processes can be reduced.

That is, in the present invention, the ohmic contact hole (120a and 120b of FIG. 5E) and the capacitor contact hole (122 of FIG. 5E) are formed in advance of the anode 114 before the source and drain electrodes 124 and 126. In addition, since the anode exposed portion (116 of FIG. 5E) is formed at the same time, the process corresponding to the existing drain contact hole (56 of FIG. 3F) can be omitted, so that the number of mask processes is reduced.

Next, in FIG. 5H, the organic light emitting layer 132 is connected to the anode 114 through the anode exposed portion (130 of FIG. 5G) on the substrate having passed through the FIG. 5G step, and corresponding to the anode. ), And a cathode 134 is formed on the organic light emitting layer 132 by using a fifth metal.

The fifth metal is preferably an opaque metal material having a work function lower than 4 eV. Examples thereof include alkali metals, and more preferably magnesium / silver alloy (Mg: Ag) and aluminum. / Lithium alloy (Al: Li) or a lithium fluoride (LiF) and a composite layer made of aluminum.

On the other hand, since the organic materials constituting the organic electroluminescent layer 132 are very weak to moisture, it is difficult to use the above-described mask process in the process after the organic electroluminescent layer 132 is formed, and thus the organic electroluminescent layer 132 A cathode 134 is not formed on the upper portion of the cathode.

Hereinafter, the organic material constituting the organic light emitting layer 132 will be described in more detail.

The organic light emitting layer 132 may be formed as a single layer, but generally, a hole injection layer, a hole transport layer, and an emission layer are sequentially disposed between an anode and a cathode. And a multilayer film composed of an electron-transport layer.

Since the hole injection layer material plays a role of facilitating hole injection from the anode, in order to lower the hole injection barrier, ITO and ionization energy (ionization potential), which are materials forming the anode, should be similar and have high interfacial adhesion with ITO.

In addition, in order to increase the external quantum efficiency, absorption in the visible light region should not be possible. Phthalocyaning copper (CuPc; Copper Phthalocyanine) is mainly used as a material currently used.

The light emitting layer first forms a light emitting layer that emits red color through a separate shadow mask, and then moves the shadow mask sideways by one pixel to move the green light emitting layer and one more space. After that, a method of forming a light emitting layer that emits blue color is mainly used.

In this way, it is important to secure sophisticated shadow masking technology and control technology.

Hereinafter, the electroluminescent mechanism of the organic electroluminescent device will be described.

When a forward voltage is applied to the small intestine of the organic light emitting diode, holes are injected into the organic electroluminescent layer (HOMO), and electrons are injected into the lower unoccupied molecular orbital (LUMO) of the organic electroluminescent layer. . Excitons are generated by excitation of the organic molecules of the emission layer by the recombination energy of the injected electron-holes. The exciter transitions to the ground state through various paths, and in this process, it is called electroluminescence.

The current density and the luminance of light emitted through the organic light emitting diode are linearly proportional, but the current-voltage characteristic shows a rectification characteristic similar to that of a diode, and the current starts to flow rapidly from the threshold voltage of several volts (V) in the forward direction. . The organic EL element is turned off by applying a threshold voltage or a reverse voltage. In addition, the current-emitting characteristic has little temperature dependence, but the current-voltage characteristic moves toward higher voltage as the temperature decreases. Therefore, when the organic electroluminescent device is voltage driven, it is difficult to obtain a stable operation. Therefore, a constant current driving method is mainly employed for driving the organic electroluminescent device.

After the cathode is formed, the organic electroluminescent device is subjected to an encapsulation process to block external moisture.

However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, according to the present invention, since the number of mask processes can be reduced, manufacturing cost and processing time can be reduced, and thus there is an advantage of providing an active matrix type organic electroluminescent device having improved production yield.

Claims (25)

A plurality of first lines formed in a first direction, a plurality of second lines formed in a second direction crossing the first direction to define a pixel region, and formed at intersection points of the first and second lines, respectively In an active-matrix organic electroluminescent device including a thin film transistor having a semiconductor layer, a gate electrode, a source and a drain electrode, opening and closing a pixel, An insulating substrate; A semiconductor layer and a capacitor electrode made of polysilicon (p-Si) formed on the insulating substrate; A gate electrode formed at a central portion of the semiconductor layer; A first insulating layer formed on the gate electrode and the capacitor electrode; A power electrode formed at a position corresponding to the capacitor electrode on the first insulating layer; An anode electrode formed in a pixel unit on the first insulating layer on which the power electrode is formed and made of a transparent conductive material; A second insulating layer positioned on the anode and having a first anode exposed portion exposing a portion of the anode; A drain electrode formed to be connected to the anode and a source electrode spaced apart from the drain electrode at a predetermined interval and connected to the power electrode through the first anode exposed portion of the second insulating layer; A third insulating layer disposed on the source and drain electrodes and having a second anode exposed portion formed at a position corresponding to the first anode exposed portion of the second insulating layer; An organic electroluminescent layer connected to the anode through the second anode exposed portion and formed at a position corresponding to the anode; Cathode electrode made of an opaque metal formed on the upper surface in contact with the organic light emitting layer An active matrix organic electroluminescent device comprising a. The method of claim 1, The first to third insulating layers are inorganic matrix organic electroluminescent devices. The method of claim 2, The inorganic insulating material is any one of a silicon oxide film (Si0 ₂ ), a silicon nitride film (Si ₃ N ₄ ) active matrix organic light emitting device. The method of claim 1, Both ends of the semiconductor layer form an ion-doped ohmic contact layer, and the second insulating layer includes first and second ohmic contact holes and a capacitor contact hole exposing portions of the ohmic contact layer and the power electrode at both ends of the semiconductor layer, respectively. An active matrix organic electroluminescent device further comprising. The method of claim 4, wherein And the source and drain electrodes connected to the ohmic contact layers at both ends of the semiconductor layer through the first and second ohmic contact holes, respectively. The method of claim 4, wherein And the source electrode is connected to a power electrode through the capacitor contact hole. The method of claim 1, The transparent conductive material forming the anode is an indium tin oxide (ITO) active matrix organic light emitting device. The method of claim 1, The opaque metal constituting the cathode is an active matrix organic light emitting device having a work function of less than 4 eV. The method of claim 8, The opaque metal is an alkali (alkali) metal active matrix organic electroluminescent device. The method of claim 8, The opaque metal is any one of a composite layer composed of a magnesium / silver alloy (Mg: Ag), an aluminum / lithium alloy (Al: Li), lithium fluoride (LiF), and aluminum. The method of claim 1, The first line is a scan line including a gate electrode and a capacitor line spaced apart from the scan line, and is a capacitor line including the capacitor electrode, and the second line is a signal line including a source electrode and a predetermined distance from the signal line. And an active matrix organic light emitting diode that is a power supply line including the power electrode. The method of claim 11, A switching thin film transistor is formed at the intersection of the scan line and the signal line, and a storage capacitor is connected to the switching thin film transistor and the capacitor line, and a driving thin film transistor is formed to be connected to the storage capacitor and the power supply line. And an anode, an organic light emitting diode, and a cathode connected to the driving thin film transistor to form an active matrix organic light emitting diode. The method of claim 1, The organic light emitting layer is a multilayer film including a hole-injection layer, a hole-transport layer, an emissive layer, and an electron-transport layer in order between the anode and the cathode. Active matrix organic electroluminescent device. The method of claim 1, The active matrix organic electroluminescent device is an active matrix organic electroluminescent device formed by vacuum evaporation. Forming a plurality of first lines in a first direction, forming a plurality of second lines arranged in a second direction crossing the first direction to define a pixel region, and the first and second lines In the manufacturing method of an active-matrix organic electroluminescent device comprising opening and closing each pixel at the intersection of the step of forming a thin film transistor having a semiconductor layer, a gate electrode, a source and a drain electrode , Providing an insulating substrate; Forming a semiconductor layer and a capacitor electrode on the insulating substrate by using polysilicon; Forming a gate electrode at a central portion of the semiconductor layer; Forming a first insulating layer on the gate electrode; Forming a power electrode at a position corresponding to the capacitor electrode on the first insulating layer; Forming an anode using a transparent conductive material on the substrate on which the power electrode is formed; Forming a second insulating layer having a first anode exposed portion for exposing a portion of the anode; Forming a drain electrode connected to the anode and a source electrode spaced apart from the drain electrode by a first anode exposed portion of the second insulating layer, the source electrode being connected to the power electrode; Forming a third insulating layer on the source and drain electrodes, the third insulating layer having a second anode exposed portion at a position corresponding to the first anode exposed portion; Forming a cathode made of an opaque metal on the organic electroluminescent layer connected to the anode and the organic electroluminescent layer connected to the anode through the second anode exposed portion; Method for manufacturing an active matrix organic electroluminescent device comprising a. The method of claim 15, Forming a first anode contact hole in the second insulating layer, and forming contact holes exposing both ends of the semiconductor layer and a part of the power electrode. The method of claim 16, And exposing both ends of the semiconductor layer to form an ohmic contact layer in which impurities are implanted by ion doping the both ends of the semiconductor layer. The method of claim 17, And the source and drain electrodes are connected to ohmic contact layers on both ends of the semiconductor layer through corresponding contact holes formed in the second insulating layer. The method of claim 16, And the source electrode is connected with a power electrode through a contact hole of the second insulating layer partially exposing the power electrode. The method of claim 15, The active matrix organic electroluminescent device is a method of manufacturing an active matrix organic electroluminescent device is formed by a vacuum deposition method. The method of claim 15, The transparent conductive material is ITO manufacturing method of an active matrix organic electroluminescent device. The method of claim 15, The opaque metal is a method of manufacturing an active matrix organic electroluminescent device is a metal having a work function of less than 4eV. The method of claim 15, The organic light emitting layer is a multilayer film including a hole-injection layer, a hole-transport layer, an emissive layer, and an electron-transport layer in order between the anode and the cathode. The manufacturing method of an active matrix type organic electroluminescent element. The method of claim 15, The forming of the first line may include forming a scan line including the gate electrode and a capacitor line spaced apart from the scan line, the capacitor line including the capacitor electrode, and forming the second line. And forming a power supply line including the signal line including the source electrode and a predetermined distance from the signal line, the power supply line including the power electrode. The method of claim 15, The first to the third insulating layer is an inorganic insulating material manufacturing method of an active matrix type organic light emitting device.